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TION A R Y - cºm. 2e2 2 & & M E CH AN I C A L S c 1 E N C E. arts, £atanufactures, - A N D - - Fºrorº II. MISCELLANEOUs KNOWLEDGE. COMPRISING: THE PURE sciences of MATIIEMAT1cs, GeoMETRY, ARITIIMET1c, ALG EBRA, &c.;-tile MIXED sciences of MECHAN ics, HYD Rost Atics, PNEU MAT1cs, optics, AND Ast RoNoMY;—EXPERIMENTAL PII ILcso pily ;-TILE FINE ARTs:–AGRICUL- TURE, AND its IMPLEMENTs; — MANUFACTURES, AND THEIR v ARIOUS PRocesses; —com MERCE AND DOMESTIC EconoM x;—NATURAL HIStory;-WITH BIOGRAPHICAL AND IIISTORICAL NOTICES OF EMIN ENT MEN, WHO HAVE ADO RN ED SCIENCE BY THI EIR INVENTIONS AND DISCOVERIES. - - —A- ~~ Hillustratch tuitſ) many #umbrel 35mgrabings. —A- -Ur- Studies serve for delight, for ornament, and for ability: they perfect nature, and are perfected by experience. Crafty men contemn studies simple men admire them, and wise men use them. Read not to contradict and confute, nor to believe and take for granted; nor to find talk and discourse, but to weigh and consider. Some books are to be read only in parts; others to be read, but not curiously; and some few to be Tead wholly, and with diligence and attention. - - º - LoRD BAcóN. BY ALEXANDER JAMIESON, LL.D. * - L O N DO N : - ;PRINTED FOR HENRY FISHER, son, AND cd. NEWGATE-STREET. 1827. . . . .” **saw-cºs-----nºw”--~~~~== == º off, and the machine ascends in the air, as in fig. 20. In order to produce such a bulk of inflammable air as is &:20. necessary for a balloon Frg.:22a+ of 30 feet in diameter, ÆVº =##### º § - ſº-ºº-ººrº Yº-º: :=EE whose capacity is 14,137 º: ####### cubic feet, there will be É required about 3900 lbs :===######### of iron turnings, 3900 lbs : of vitriolic acid, and 19,500 lbs of water, with which the balloon will not be above three-quar- ters full. The usual way now of filling a balloon with the carbonated, or carburetted, hydregen gas, the same as the streets are lighted with, is to introduce it through any service pipe into the balloon, from any of the station pipes connected with the gasometer of any of the great gas manufactories in the - * - neighbourhood of the aeronaut's ascent. Of course, all the apparatus of casks, &c. is done away with: but some degree of caution is requisite in managing the machine when afloat, and highly elevated; for should the larger valve in the top of the balloon be opened by the aeronaut in place of the smaller one, as unfortunately was done by the late Mr. Harris, too much gas may escape, and the vehicle be precipitated with 16 A E S A F F , DICTIONARY OF MECHANICAL SCIENCE. great velocity perpendicularly to the ground. Mr. Harris ascended from the City-Road, London, May 25, 1824, and in the neighbourhood of Croydon, Surrey, his balloon came rapidly to the ground, from his having pulled the cord of the larger in place of that of the smaller valve, to descend; and he was killed on the spot. His fair companion, a young lady, was very much injured by the fall, , , . Construction of Balloons.—The balloon itself is composed of gores of silk, fig. 21, covered with caoutchouc warnish, and probably 30 feet diameter. A net is spread over the whole hemispherical surface. To this a car or boat is suspended by ropes, so as to - hang a few feet below the bal- loon; and in or— der to prevent the bursting of the machine, a valve i within the other, to allow the gas to escape when the aeronaut wishes to descend. The basket may be 8 feet long, 4 wide, and 3} deep, of wickerwork; and the weight of the whole apparatus about 5% cwt. including the voyager.—The conduct of balloons has been attempted to be placed under the power of the aeronaut, by means of wings or oars, fig. 22. Blanchard used this sort of wing of silk, stretched upon cane, and used edge-- wise in the direction in which the balloon is . . driven.—Lunardi tried Rāś shutters of silk, or rather valves, a,b, side only, and be moved on ... . the flat side in the direction in Kºš. which the machine is impel- led. But the aeronaut has little or no power over the machine when it is suspended - º- in the air.—Baldwin, who ascended from Chester in 1785, com- pares the sensation of ascending to that of a strong pressure from the bottom of the car upwards against the soles of the feet. At the distance of one mile he fancied he had gone seven. The river Dee appeared red, the city diminutive, the town blue, and all reduced to one grand enchanting level; the clouds seemed a sea of fleecy cotton, the thunder-clouds like the dense smoke of cannon. The shadow of the balloon upon the white floor of clouds, was, at times, no bigger than an egg; at others, greatly increased, and surrounded with the most captivating iris or rainbow. At four miles high the air was warmer than on carth: the sun was hottest when the balloon was stationary.—Mr. Sadler, who, in the summer of 1824, ascended from Liverpool, erected an extensive apparatus for filling his balloon with gas, of a quality sufficiently buoyant to bear up more than the usual weight. The apparatus consisted of a large boiler, heated by two furnaces, and a number of cylindrical retorts, communicating by pipes, leading to a gene- ral conduit;-the whole being on the principle of simply decom- posing water by means of heated iron filings, borings, and turnings. The balloon was 34 feet diameter, by 42 feet high, covered with 560 square yards of silk, containing 28,000 cubic feet of gas, which would raise 12 cwt. from the earth. The balloon arose at 3 p.m. and took a S.E. course towards Ches- ter, near which place it descended between 5 and 6 p.m. The mountains of Wales were visible to Mr. Sadler and his com- panion; but the sea was hid by clouds.-On the 14th of June, 1824, Messrs. Green and Sparrow ascended from the gas- works of Oxford, about 3 p.m. The balloon travelled 22 miles towards Henley, where it was brought down. Mr. Sparrow was thrown out of the car, when the balloon came first in contact with the earth, but received no injury.—A Mr. Graham and his wife, about the same period, ascended from London, and descended about 14 miles from Brighton, after a voyage of 1 hour and 20 minutes, without experiencing any accident.— Since the above was written, poor Sadler was killed in one of his enterprising voyages. - . AESCULUS, in Botany, horse-chesnut, which, as a powder, excites sneezing: infused, it is good for complaints in the a Balloon. § Fig.22. s placed in it; sometimes two valves, one head and eyes. The bark of the tree is considered a good febrifuge. - r AESTIVAL, belonging to summer, as the aestival solstice, sign, &c. * * - . . . . ºffer, in Chemistry, a light, volatile, and very inflam- mable liquid, produced by distillation of acids with spirits of wine. The too frequent use of aether is very injurious to the nervous system; yet many people take it freely. AETHUSA, fool's parsley, possesses poisonous qualities. AETITES, eagle stones, flinty crustated pebbles, of a yellow colour, hollow within, and containing a nucleus, which rattles if the stone be shaken. : -- . . . AFFERERS, in Law, persons appointed in courts leet, | courts baron, &c. to settle the fines upon those who have been guilty of faults arbitrarily punishable. - AFFETTUOSO, or Con Affetto, in Music, whatever is played in a moving style. - AFFIDAVIT, in Law, an oath in writing, sworn before a competent authority. - - AFFINITY, in Chemistry, is that power which tends con- tinually to bring particles of substances together which are disunited, and which retains in connection, with more or less force, those already in a state of combination. When olive oil and water are shaken together, they refuse to act upon each other, and separate according to the order of their den- sities, the oil swimming above the water. Oil and water will not mix intimately; they will not combine; and are said to have no chemical attraction or affinity for each other. But if oil and soap lees, or solution of potash in water, be mixed, the oil and the solution blend together, and a species of soap will be formed, which may be procured as a soft solid substance | by evaporating a part of the water. This is an instance of com- | bination ; and solution of potash and oil are said to attract each : other chemically, or to have an affinity for each other. A spoonful of salt, thrown into a vessel of water, diffuses itself through the whole of the ſluid, and the salt is combined with the water; the water and the salt have an affinity for each other, and cannot be separated by any mechanical means: but if another substance be introduced, to which water has a greater affinity than it has to the salt, it will quit the salt, to unite to this third substance. If alcohol be the third body, the water will leave the salt to join the spirit; and the salt, by its superior gravity, will be precipitated in the vessel. Alcohol will dissolve camphor, aud the fluid be perfectly clear, which is another instance of chemical combination ; the two substances have a strong affinity for each other: but the spirit has a still stronger affinity for water than for the camphor; and if a little of that fluid be added to the solution, the cam- phor will fall down in flakes, that is, in a solid form. Differ- ent bodies unite with different degrees of force; and hence, one body is capable of separating others, from certain combi- nations: and in consequence of the same circumstance, mutual decompositions of different compounds take place. This has been called double affinity, or complex chemical attraction. Thus, if an aqueous neutral solution of lime and nitric acid, and a like solution of magnesia and sulphuric acid, be mixed toge- ther, the lime will quit the nitric acid, to unite to the sulphuric acid, and the magnesia will leave the sulphuric acid, to com- bine with the nitric acid. The combination of nitric acid and magnesia will remain in solution; but the compound of lime and sulphuric acid, being only slightly soluble in water, will, for the most part, be precipitated in the form of a white powder. Every substance has its peculiar affinities to the various other substances presented to it. If all bodies had the same degree of affinity with each other, no change could take place amongst them; and we should not be able to displace any principle by presenting one body to another. It is in consequence of this difference in the affinities, that all chemical decompositions are affected ; and all the operations of nature and art are founded upon it. Hence arises the terms, simple affinity, double affinity, &c. . Two principles united, and then separated by means of a third, afford an example of simple affinity: it consists in dis- placing one, principle by the addition of a third. The body. disengaged is called the precipitate; the substance used to separate the compound, is called the precipitant. An alkali precipitates metals from their solutions. . Sometimes the new # * ſºrºraeuaerae， ſae， ， ， ， ، ، ،…".…--…" |-- ----ſae， ，deae，… |-|-_|- | 1 | 1 |LV7， ſ.º.）， „2//Aſ yº º/ ..///ſ.Laeø| .9°. *****…yaev ，）| |„…，∞，∞）：|- ||-------ſoittaeo，|- |// ±√（/√∞'，ſı，s~~~| |"… ， -，-（.*）/，~.| |Awarae' （）/// 7*| |-·|- ||wºw wzºrºsae· |-|-|-_ ·ſae .………！！ "¿¿.*---- ||„Z“..…：…¿?， ，|-~^| |-·：-’ √----| |…….……， …7，… --★ →'，|- |·……………|-|-~~~~ ~~3 |-|~// ******…--ſae.|- |-= |-… .|- |wae-· Y^**';ºg oostenºt， ，<！--|-- - |-|-- _-----------------------------------------， -jõ （5）----------------- |-…….…… -- |- ，！ ||- | ſae ，| |-|×·rae -_ *-| Sº'， -| |· ·…· - -||-****…|-|- ·- -|ſae …， ~----•■■■ºz. z º. aerolºurs• |--~~~~，~~~•s.|----- ………………- |- |- };ºz < *1 ; --~~ Q/ manner, and designed to keep the corn together after it is cut; so that, instead of its falling in a confused state, the reaper can lay it down in a regular and compact manner. The handle, a b, is 4 feet 3 inches long; the blade, b c, about 2 feet; the upright, b d, 1 foot 10 inches. 11. In the Collector Scythe, fig. 32, the handle, a, is 4 feet 1 inch ; the blade, b, 2 feet 8 inches; the upright, 12inches: the collector is of cloth, and may be added to the common scythe Fig. 32. The Collcotoſ. Cº ... a Pºss- with a piece of sheet iron at the tip of the blade. The collector is fixed on by stout iron wires, c, and will be well enough un- derstood from our engraving. This instrument is preferable to the above, though both are excellent. 12. The Irrigating Machine, is an instrument designed to raise water to a great height for the irrigation of land, in such situa- tions as have the advantage of a small fall: it depends on the principle of Hero's fountain, and it may properly be inserted here. See Hero's fountain, article Jet d’EAU. Fig. 33, a, b, is the stream of water: b, c, c, represents the waterfall, supposed to be 10 feet: d, e, are two leaden or cast iron vessels, contain- ing about 4 or 6 gallons of water, and f, g, h, i, k, l, are leaden or iron vessels holding about two quarts each : o, p, are two cocks, each of which passes through two pipes, opening, the one, and closing the other: q, r, is a water balance, which works on its centre s, and by which the cocks o and p are alter- nately turned : t, u, and w, w, are air-pipes made of lead, both 1} inch diameter internally; and y, z : y, z : y, z - are Water- pipes, each 1 inch diameter. The pipe b, e, c, is always full from the stream a,b; the small cisterns, g, i, l, and the large one, d, are supposed to have been previously filled with Water. The fluid may then be admitted by turning the cock o; through 20 A. I R. A I R. DICTIONARY OF MECHANICAL SCIENCE, the pipe c, e, into the larger " cistern e. The water will then press the air confined in the cistern e, up the air-pipe w, w, and force the fluid out of the cisterns g, i, l, into those mark- ed h, k, &c. At the same time, by opening B, the water and condensed air, which previ- ously existed in the large cis- tern d, and in the less ones j, h, k, will be discharged at B. In a short time, the water ba- lance, q, r, s, will turn the cocks o, p, and push out the water, opening, during this operation, the opposite ones; the cisterns f, h, k, are emptied in their turns by the condensed air from the cistern d, as the water pro- gressively enters the latter pipe b, c. These, and many more, which our limits compel us to omit, are the most useful ma- chines used in agriculture: Carts, waggons, threshing mills, &c. we shall describe in their proper places, agreeably to the alphabetical arrangement of this Dictionary. AGRIMONIA, Agrimony: hemp and water-hemp agrimony, occur in botany. Common agrimony is aperient and deter- gent; good in scorbutic disorders, and debility of the intes- tines. Digested in whey, it makes a good and useful diet- drink for the spring. AGROSTEMMA, wild lichens, or campions: AGROSTIS, bent-grass. Agrostographia, the history or description of grasses. AGUE, a periodical fever, which, according to the different returns of the feverish paroxysms, is denominated tertian, quartan, and quotidian. AHEAD, a sea term, expresses the situation of any object in advance of the ship; and is used in opposition to astern, which denotes the position of any object behind the ship. AHULL, the situation of a ship when all her sails are furled, on account of the violence of the wind, and when, hav- ing lashed her helm on the lee side, she lies nearly with her side to the wind and sea, her head being somewhat inclined in the direction of the wind, º AIDS, in the Manege, cherishings used to avoid the neces- The inner aids are the inner heel, leg, rein, sary corrections. &c.; the outer aids, the outer heel, leg, rein, &c. - AIGUHSCE, in Heraldry, a cross with its four ends sharp- ened into obtuse angles. AIR, a thin, elastic, transparent fluid; ponderous, compres- sible, and dilatable. See ATMosPHERe. AIR, in Music, melody in general, a tune: AiR-Pipes, an invention due to Mr. Sutton, a brewer, of London; being intended for clearing the holds of ships, and exhausts the air in a proper vessel. | that of the receiver alone. opening upwards, as have also the pistons their valves. other close places, of their foul air. The principle upon which this contrivance is founded, is well known; being no other than the rarefying power of heat, which by causing a diminution in the density of the air in one place, allows that which is in con- tact with it to rush in, and to be succeeded by a constant Sup- ply from remoter parts, till the air becomes every where equally elastic. If, therefore, one end of a long tube be placed in the hold, or place to be purified, while the other end of the tube be sufficiently heated, the foul air will be constantly drawn up, | and supplied by fresh air from above. AIR-Pump, a popular pneumatic machine, that draws out or The construction of this machine, and its principle of action, may be thus explained, fig. 34:—Let B represent a section, (the section of a perfectly uniform metallic barrel or pipe,) com municating with the glass receiver A, by means of the inferior tube t, t , let P be a piston, attached to the rod R, and fitting the barrel air-tight; v and v, are two valves opening upwards, one in the piston, the other in the end of the tube t t. CD supports the receiver, which is placed on wet lea- ther collars. When the piston-rod is pushed down, the air in the barrel is c compressed, the lower valve shut, but the valve of the piston opens, and allows the air in the barrel to rush out. When the piston is drawn up, its valve is shut by the external atmosphere; but the air in the receiver pushing up the valve v of the tube, rushes into the barrei, which is again filled with air as much rarer than before, as the contents of both barrel and receiver exceed Every stroke diminishes the den- sity of the confined air in a constant proportion, namely, as much as the whole content exceeds that of the cylinder or barrel; and consequently, the sum of as many diminutions as there are strokes of the piston, will shew the whole diminution by all the strokes: So, if the capacity of the barrel be equal to that of the receiver, in which the communication-pipe is always to be included, then, the barrel being half the sum of D i the whole content, half the air will be drawn out at one stroke; and consequently, the remaining half, being dilated through the whole or first capacity, will be of only half the density of the first; in like manner, after the second stroke, the density of the remaining contents will be only half of that after the first stroke, that is, only 4 of the original density: continuing this operation, it follows that the density of the remaining air will be # after 3 strokes of the piston, ſº after 4 stroks, J. after 5 strokes, and so on, according to the powers of the ratio 3 ; that is, such power of the ratio as is denoted by the number of the strokes. In like manner, if the barrel be # of the whole con- tents, that is, the receiver double of the barrel, or 3 of the whole contents; then the ratio of diminution of density being #, the density of the contents, after any number of strokes of the piston, will be denoted by such power of #, whose exponent is that number; namely, the density will be 3 after one stroke, (3) or ; after two strokes, (3) or # after three strokes, and in general it will be (#)n after n strokes: the original density of the air being 1.. - The Common Air-Pump, fig. 35, is both portable and con- venient. E, F, G, H, is a square table of wood; A, A, two strong barrels of brass firmly fixed by the head bar T, T, and the pillars N, N. These barrels communicate with two tubes, as shewn in diagram 34, each having its valve Hn this machine the pistons are worked by a cog-wheel fixed in the bar TT, and turned by the handle B. The teeth of the | wheel work in the piston racks C, C. PQ, a circular brass AIGHENDALE, in Lancashire, a liquid measure of 7 quarts. plate to hold the receiver, has a hole in its centre that comma- nicates with the piston tubes. In the piece D, at V there is a screw which closes the orifice of one pipe for the purpose of admitting the external air when required. LM is the glass receiver, out of which the air is to be exhausted, when placed on the plate PQ, which is previously covered with a wet sheep- skin, or smeared with wax, to prevent the air from insinuating under the edge of the glass. When the handle B is turned, A I R. A 1 R. DICTIONARY OF MECHANICAL SCIENCE. 2i. one of the pistons is raised, and the other depressed; conse- quently a void space is left between the raised piston and the lower valve in the correspondent barrel: the air contained in the receiver LM communicating with the barrel by the orifice K, im- mediately raises the lower valve by its spring, and expands into the void space, and thus a part of the air in the receiver is ex- tracted. The handle then, being turned the contrary way, raises the other piston, and performs the same act in its correspond- C AirPump. 5|| Fig35 ; 2 * C ; - sº-sº \ .#| IE ent barrel: while, in the mean time, the first-mentioned piston being depressed, the air by its spring closes the lower valve, and, raising the valve in the piston, makes its escape. The motion of the handle being again reversed, the first barrel again exhausts, while the second discharges the air in its turn : and thus, during the time the pump is worked, one barrel exhausts the air from the receiver, while the other discharges it through the valve in its piston. Hence it is evident, that the vacuum in the receiver of this air-pump (and the same may be said of all others) can never be perfect; that is, the air can never be entirely ex- hausted : for it is the elasticity of the air in the receiver that raises the valve, and forces air into the barrel; and the barrel at each exsuction can only take away a certain part of the remaining air, which is in proportion to the quantity before the stroke, as the capacity of the barrel to the sum of the capacities of the barrel, receiver, and communicating pipe. And we have shewn the ratio of exhaustion, going on in geometrical progression, until the elasticity of the included air is too feeble to push up the valve of the piston, when the receiver is said to be exhausted.—The specific gravity of air may be very accurately ascertained by means of this machine, and the method is as follows: To the neck of a glass bottle, made in the form of a Florence flask, adapt a cap and valve opening outwards, screw it on the pump, and exhaust it to a known degree, which will be shewn by the gauge attached to the pump for that pur- pose; then from the weight of the bottle before and after exhaustion, we have the weight of the exhausted air; and from the ratio of the height of the mercury in the gauge to the standard altitude, we know the proportion which the exhausted part bears to the whole air originally in the vessel, whose weight is therefore known. Subtracting this weight from the weight of the vessel when full of air, there will remain the weight of the vessel itself: fill it with water, and weigh it, and subduct the weight of the vessel from this weight; the remain- der is the weight of a bulk of the same magnitude with the air which fills the vessel, and whose weight was also previously ascertained. Following this method, it has been found by a mean of several experiments, that the specific gravity of air is to that of water as 1.222 to 1000, very nearly, when the baro- meter stands at 30 inches, and in the mean temperature of 55° of Fahrenheit's thermometer. This agrees with the result already given.—Some of the principal effects and pheno- mena of the air-pump are the following:—That, in the ex- hausted receiver, heavy and light bodies fall equally swift; so, a piece of metal and a feather fall from the top of a tall receiver to the bottom exactly together: That most animals die in a minute or two: but, however, that vipers and frogs, though they swell much, live an hour or two; and after being seem- ingly quite dead, come to life again in the open air: That Snails survive about ten hours; efts, or slow-worms, two or three days; and leeches five or six : That oysters live for 24 hours: That the heart of an eel taken out of the body, con- tinues to beat for a good part of an hour, and that more briskly than in the air: That warm blood, milk, gall, &c. undergo a considerable intumescence and ebullition : That a mouse, or other animal, may be brought, by degrees, to sur- vive longer in a rarefied air, than it does naturally: That air may retain its usual pressure, after it is become unfit for respiration: That the eggs of silk-worms hatch in vacuo: That vegetation stops: That fire extinguishes, the flame of a candle usually going out in one minute, and live charcoal in about five minutes. - . Cuthbertson's Air-Pump, is exhibited in fig. 36, with its two principal gauges screwed into their places; but these are seldom used, except when great delicacy is required ; for in the common experiments one of them is removed, and a stop- Screw put in its place : and when all the three gauges are used, the stop-screw B admits the air into the receiver. The dotted lines represent a transverse bar that keeps the barrels steady : N, N, are two slips of wood that keep this bar down: O, O, are screws that fix it. NJ Fig. 37 is a section of one of the barrels with all its internal parts, and figs. 38, 39, 40, and 41, are different parts of the pis- ton, proportioned to the size of the barrel, and to one another. In fig. 37, C D represents the barrel, F the collar of leathers, G. a hollow cylindrical vessel to contain oil. R is also an oil- vessel to receive the oil which is drawn, along with the air, through the hole a a, when the piston is drawn upwards; and, when this is full, the oil is carried over with the air, along the tube T, into the oil-vessel G. c c is a wire which is driven G f 22 A I R. A. I. R. DictionARY of MECHANICAL science upwards from the hole a a by the passage of the air; and as soon as this has escaped, it falls down again by its own weight, shuts up the hole, and prevents all return of the air into the barrel. At d d t are fixed two pieces of brass, to H| |- keep the wire e c in a vertical di- º rection, that it may accurately shut "|| || the hole. H is a cylindrical wire or rod which carries the piston I, in and is made hollow to receive a I long wire q q, which opens and º- shuts the hole L; and on the other F end of the wire O is screwed a nut, which, by stopping in the nar- rowest part of the hole, prevents EC O - the wire from being driven up too º *- far. This wire and screw are more clearly seen in fig. 42 and 41; they “ | slide in a collar of leather r r, fig. 42 and 40, in the middle piece of the piston. Fig. 38 and 40 are the two mean parts which compose the piston, and when the pieces 39 and 41 are added to it, the whole is represented by fig. 42. Fig. 40 is a piece of brass of a conical form, with a shoulder at the bottom. A long hollow screw is cut in it, about two-thirds of its length, and the remainder of the hole, in which there is no screw, is of about the same diameter with the screwed part, except a thin plate at the end, which is of a p width exactly equal to the thick- ſº ness of q q. The part of the inside of the conical brass in which no thread is cut, is filled with oiled leathers, with holes through which - q q can slide stiffly. There is also M a male screw with a hole in it, : . fitted to q q., serving to compress the leathers r r. In fig. 38, a a a a is the outside of the piston, the inside of which is turned so as exactly to fit the outside of fig. 40, b b are round leathers about 60 in number, c c is a circular piece of brass of the size of the leathers, and dd is a screw serving to compress them. The screw at the end of fig. 39 is made to fit the screw II/ Ge * Ali; ſlº Fig.1.1. in fig. 40. Now if fig. 41 be pushed into fig. 40, this into fig. 38, and fig. 39 be screwed into the end of fig. 40, these will compose the whole of the piston, as represented in fig 42. H in fig, 37 represents the same part as H in fig. 42, and is that to which the rack is fixed. If, therefore, this be drawn upwards, it will cause fig. 40 to shut close into fig. 38, and drive out the air above it: and when it is pushed downward, it will open as far as the shoulder a a will permit, and suffer air to pass through, A A, fig. 43, is the receiver plate. B B is a long square piece of brass, screwed into the under side of the plate, through which a hole is drilled corresponding to that in the centre of the receiver-plate, and with three female screws b, b, c.—The rarefaction of the air in the receiver is effected as follows: Suppose the piston at the bottom of the barrel. The inside of the barrel, from the top of the piston to a, contains common air. When the rod is drawn up, the upper part of the piston sticks fast in the barrel till the conical part connected with the rod shuts the conical hole, and its shoulder applies close to its bottom. The piston is now shut, and therefore the whole is drawn up by the rack-work, driving the air before it through the hole a a, into the oil-vessel at R, and out into the room by the tube T. The piston will then be at the top of the barrel at a, and the wire gq will stand nearly as represented in the figure just raised from the hole L, and prevented from rising higher by the nut O. During this motion the air will | expand in the receiver, and come along the bent tube m into the barrel. Thus the barrel will be filled with air, which, as the piston rises, will be rarefied in proportion as the capacity of the receiver, pipes, and barrel, is to the barrel alone. When the piston is moved down again by the rack-work, it will force the conical part of fig. 40 out of the hollow part fig. 38, as far as the shoulders a a. Fig. 42 will rest on a a, fig. 38, which will then be so far open as to permit the air to pass freely through it, while at the same time the end of q q is forced against the top of the hole, and shuts it, in order to prevent any air from returning into the receiver. Thus, the piston moving down- wards suffers the air to pass out between the sides of fig. 38 and 40; and, when it is at the bottom of the barrel, will have the column of air above it: and, consequently, when drawn upwards it will shut, and drive out this air and, by opening the hole L at the same time, will give a free passage to more air from the receiver. This process being continued, the air of the receiver will be rarefied as far as its expansive power will permit. For in this machine there are no valves to be forced open by the elasticity of the air in the receiver, which at last it is unable to effect. There is, therefore, nothing to prevent the air from expanding to its utmost degree. - Mendelssohn's Air-Pump.–It has been objected to Cuthbert- son's air-pump, that its complex structure renders it difficult to be cleaned and put together, and kept in Pyaa. proper order for ex- periments. Accord- ingly, Mr. Mendels- sohn, a mathematical instrument-maker, re- * Sº s ºp M siding in Great Sur- H., "sºlini rey – street, Black- iº iſºlºiſt ºf F friars' - Road, having & T-II- reflected upon the diſficulties just allud- ed to, was led to the construction of a more simple air-pump, ca- pable of being easily put together when- | —F. ever cleaned, and re- |D quiring that opera- | tion seldom. He re- jects the tube, in com- *— `" mon air-pumps, lead- ing from the valves to the receiver, toge- ther with the cock that shuts this pipe: the receiver is putim- mediately upon the || valves which are in the - top of the barrels; and i the rack-work and pinion being underneath, the whole instru- A. I. R. A J U 23 , DICTIONARY OF MECHANICAL SCIENCE. mentis inverted. In fig. 44you have a full sight of Mendelssohn's air-pump, wherein AB, CD, are cylinders of glass, ground and polished inside. E and F, valves allowing the cylinders to communicate with the receiver O, through two very short canals a b, c d, fig. 45, and the cock G. Two other JBL valves that open into the O atmosphere, are within the covers i and k, as may be seen in fig. 45, where e represents one of them. MN, the receiver plate. P Q barometer gauge. H K and IL, brass pil- lars that support the whole, RSVW, the usual rack-work, with a double winch l m. The whole in- strument is fixed upon a mahogany table. RS, WV, support the racks and the diagonals, on which the pinion of the cog-wheel moves.—To shew how this pump acts, it will be sufficient to ex- plain the action of one cylinder,because the other is in all parts like it. E - is a conical metallic valve, from which a canal goes through the cock G up to the receiver, as is seen in fig. 45 and 46, where all the parts are marked with the same letters. ET is a steel rod going through a leather box in the piston U. The top of this rod is fixed to the - valve E, and its bottom sº part slides in a small hole º with an allowance of 0.1 ...; inch up and downward, §§ consequently the valve E can move no further. When the piston de- scends, it opens the valve by pushing the rod to the bottom of the hole. Then it slides down the rod ET, and the air from the re- ceiver has access to the . cylinder. When the pis- ton returns, it lifts the rod ET, and shuts up the valve. Then the piston slides along the rod to the top of the cylinder, condensing the air above it, which, by the least condensation, opens a valve e, fig.46, and escapes freely into the atmosphere. This last valve has neither spring nor additional weight to shut it, but shuts by its own weight. (about a quarter of an ounce,) as soon as the piston is arrived at the top of the cylinder. The cylinders are made of glass, and the pistons of tin, so well fitted as to be air-tight, without the interposition of any leathers. The friction of these two bodies is remarkably small ; a sufficient proof that they will be durable. They possess the further advantage of being capable of standing for even six months; after which time they will serve without being cleaned or repaired, because they are not liable to be corroded by the oil which they contain, an incon- venience too general in brass cylinders. If the present pump should want cleaning, take off the top piece gh, by unscrewing the nuts H and I, when this piece, with all the apparatus upon it, will come off. Then each cylinder may be siid off from the piston, wiped and replaced, after having greased it inside with a little sweet oil ; the top is then put in its place, and the two nuts H and I being screwed upon it, the instrument is ready. Neither racks nor pinion need to be taken out of their places, O J º* - §- N s F.%.46. | E B -msº rus the cylinders standing above them. The cock is constructed so, that, being in the situation represented in fig. 45, the com- munication is open between the cylinders, the receiver, and the barometer-gauge, and, by a quarter of a revolution, the cylin- ders are excluded, the receiver and gauge being still left in communication. A little stopper, ground into the cock, being open, air is admitted into the receiver, if it is required. The glass cylinders, the method of the valves opening, are new; the metallic pistons, without leathering, add to their durabi- lity, and lessen the labour of pumping. In short, the whole is vastly superior to the common pump. AIR LAMP, a pneumatic machine, formed by the combina- tion of hydrogen gas and electricity, which by turning a stop- cock, produces a flame that may be regulated at pleasure. AIR GUN, fig. 47, a pneumatic instrument, which will drive a bullet with great violence by means of condensed air forced into an iron ball, B, by means of a condenser. The operation depends upon the elastic power of air, which increases in pro- portion to the degree of condensation imposed on it. Now the elastic power of fired ... gunpowder being equal to the pressure of 1000 atmospheres, or 1000 times greater than that of common air, it fol- lows, that in order to produce the same effect with an air-gun as with a firelock, the air must be compressed into one- thousandth part of its natural bulk; and for all F#9.4 2. inferior degrees of condensation, the effect will B be proportionally diminished; and as the vélo- cities with which equal balls are impelled, are Cº. directly as the square roots of the forces acting i : Q- F-> upon them, we shall be able always to estimate the effect previous to any explosion taking place. - The Condenser, fig. 48, forces the air into the Fººls ball B; at the end a is a male screw, on which the hollow ball B is screwed, in order to be filled with condensed air. You set your feet on the rod h h, take the handle i i into your hand, and pump the ball b full of air, which the screw a A secures till you fasten the ball to the gun for use. * * ~ * The AIR-Dagger, fig. 49, is thus produced. A B C is a thin partition of a room down to the floor, with an apparatus for a good convex lens, H, turned outwards into the room nearly in a horizontal di- rection, so as to be viewed by a person stand- ing at F. The (i. large concave jº mirror D is sup- ported at a pro- per angle, to reflect upwards D II through H the glass in the par- - --- --> tition B, images of objects at E - C presented to- Wards the mir- A. ror below. A strong light from a lamp L, being directed on the object, and no where else, than to the eye of the spectator F,in a darkened room; it is truly surprising and admirable to what effect the images are reflected up in the air at G. Exhibitions of spectres are formed on this principle of catoptrics. AIRA, in Botany, hair-grass. AIRS, in the Manege, the artificial motions taught horses, as the demivolt, curvet, capriole. - AIRY, or AERIE, the nest of a hawk or eagle. plicity, the three signs, Gemini, Libra, Aquarius. AJUGA, in Botany, the bugle. , AJUTAGE, a tube fitted to the mouth of the vessel through which the water of a fountain is played : and to the different variety of form and structure of ajutages may be ascribed the great difference in fountains. * AIRY tri- A L C A L G. ºf CTIONARY OF MECHANICAL SCIENCE. ALAE, the lobes of the liver: the cartilages of the nostril. ALABASTER, a mineral, differing from marble in being combined with sulphuric acid. - - ALARM, the firing of a gun, &c. to give notice of an enemy, &c. Clocks and watches sometimes have Alarms, or Alarums. - ALARM Bell, that rung upon any sudden emergency: Alarm post, a rendezvous: Alarm, in Fencing, a challenge. ALBA-FIRMA, rent paid in silver, and not in coin, which was called black mail. - ALBIREO, a star of the fourth magnitude, in the Constella- tion Cygnus.--ALBoRo, a small red fish caught in the Mediter- ranean.—AlbucA, bastard star of Bethlehem.—ALBUGo, a white spot on the cornea of the eye, that produces blindness. * ALBUMEN, the white of an egg; an animal or vegetable substance. ALCE, the elk.—ALCEA, holly-hock.-ALcedo, the kingfisher. ALCHEMILLA, ladies’ mantle ; both the leaves and roots of which might be of use where mild astringents are required. ALCHEMY, that branch of Chemistry which had for its principal objects, the transmutation of metals into gold; the panacea, or universal remedy; an alkahest, or universal menstruum ; an universal ferment; and many other things equally ridiculous.—Alchemy took its rise among the Arabians, about the commencement of the fourth century. This delusive dream holding out a bait to avarice, soon attracted a host of followers. Intoxicated with the idea of boundless wealth, they occupied their time in searching for the philosopher's stone, and for a panacea or universal remedy, which should cure every disease, and confer the boon of immortality on the fortunate discoverer of the invaluable secret. Dioclesian, fearful that the visions of the alchemists might be realized, ordered all their books to be burnt. Roger Bacon the alche- mist was excommunicated by the pope, and suffered ten years imprisonment for supposed dealing with the devil; and Para- celsus was thought to have an evil spirit in the pommel of his sword. The language of this prince of alchemists was a tissue of boasting and falsehood: he promised immortality in this world to his disciples, but his own death, in 1541, opened the eyes of his deluded followers, and blasted their sanguine hopes. ALCOHOL, spirit of wine highly rectified: it is light and inflammable, and being highly antiseptic, is used to preserve animal substances. The spirit of wine of commerce is only an approximation to the state of alcohol, and it is found in the shops of every degree of strength above that of proof spirit, but divested of all colour. It is obtained merely by a re- distillation of proof spirit;-but to free spirit of wine, as much as possible, from the water with which it is always more or less combined, and to bring it to the state of alcohol, the aid of other processes besides that of distillation are necessary. To obtain pure alcohol, Rouelles, a very able French chemist, recommends to draw off half the spirit in a water bath; to rec- tify this twice over, drawing off two-thirds each time; then to add water to this alcohol, which will turn it milky by separat- ing the essential oil still remaining in it; afterwards to distil the spirit from the water, and rectify it by another distillation. Alcohol is not, however, in this state quite pure; it may yet be freed from a portion of water, by means of an alkaline salt. For this purpose, muriate of soda (common salt) may be advantageously employed, by first depriving it of its water of crystallization by heat, and adding it hot to the spirit. The subcarbonate of potashis, however, considered to be preferable. About a third part of the weight of the alcohol should be added to it in a glass vessel, be well shaken, and then allowed to sub- side. The salt will be found to have absorbed water from the alcohol, which being decanted, more of the salt is to be added, and the process continued until the salt falls dry at the bottom of the vessel. The alcohol must now be subjected to a final distillation in a water bath, to deprive it of the red tint obtained from the potash, as well as from the alkali held in solution. Dry muriate of Jime will have the same effect of ab- stracting the water from the alcohol, as the alkalijust mentioned. Alcohol being much lighter than water, its specific gravity is used as a test of its purity. Fourcroy considered it as recti- fied to the highest point when its specific gravity was 829, that planted the alembic of the al- chemists. ALEXANDERS, a plant usually found growing wild of water being 1000; and this is perhaps nearly as far as it can be carried by mere distillation: by the addition of alkali, it may be brought to 813, at 60 Fahrenheit. According to the London College, it should be 815. The uses of alcohol are various; it dissolves with great facility the resins and essen- tial oils, also camphor, bitumen, and various other substances, which renders it of great service in pharmacy, in various other arts, and to the perfumers in particular. When diluted with an equal quantity of water, constituting what is called proof spirit, it is used for extracting tinctures from vegetable and other substances; the alcohol dissolving the resinous, and the water the gummy parts. From its giving a steady heat with- out smoke, when burned in a lamp, it is extensively employed for heating water on the tea-table; and in many chemical operations, it is found extremely useful. It is in common use in preserving anatomical preparations, and many subjects of natural history. * - ALCOR, a star in the tail of the constellation of the Great Bear. ALCORAN, the Mahometan’s Bible. See Ko RAN. AECOVE, in Architecture, a recess, or part of a ‘chamber separated by an estrade or partition of columns, and other corresponding ornaments, in which is placed a bed of state, and sometimes seats to entertain company. ALDEBARAN, a star of the first magnitude in the constel- lation Taurus, called also the Bull's eye. ALDER TREE. The alder grows in wet situations; its wood is useful in machinery, as cogs for mill-wheels, pumps, water pipes, &c.; the bark is useful in tanning, and in dyeing black, by the addition of copperas. - ALE, a fermented liquor, prepared either from wheat, or rye, or millet, or oats, or barley, or the berries of the quick bean. See BREWING. ALE, To Mull. Put a pint of strong ale into a saucepan, with three or four cloves, nutmeg and sugar to your taste : set it over the fire, but whenever it boils, take it off, and let it cool. Beat the yolks of two eggs with a little cold ale; put this mix- ture to your warm ale, and pour the whole several times from your saucepan into a mug. Set it over a slow fire; heat it a little; then take it off again, and heat it three or four times, till it is quite hot, and then serve it up with dry toast. ALE Commer, an officer in London, who inspects the measures used in public-houses, chosen by the liverymen in common-hall, on Midsummer day. Their places are now only regarded as sinecures for decayed citizens. - ALEE, in sea language, when the helm is moved over to the sea-side, it is said to be alee, or hard alee. * ALEMIBIC, fig. 50, a chemical - vessel, usually made of glass or copper, and used in distillation. The bottom part A is called the cucurbit, or boiler; B is the head, or capital; C is a glass-tube, through which the sublimed sub- stances pass into D, the receiv- cr. Retorts, and the common still worm, have antirely sup- among the rubbish of old ab- # beys; it was much esteemed by the monks : and to the poor who use it, affords a wholesome article of food. ALGA, in Botany, lichen 5–ALGE, flags, one of the seven natural families into which the whole vegetable kingdom is divided by Linnaeus: they are properly plants whose roots, leaves, and stems, are all one ; as sea-weeds, &c. ALG AROTH, an oxide of antimony, obtained by washing the butter of oxymuriate with pure water. A.LGEBRA, the science of Analysis, which, reasoning upon quantity or number by symbols, examines in general all the dif- ferent methods and cases that can exist in the doctrine and cal- culation of numbers. We have no records which enable us to determine anything with regard to the date or author of this very important science; having arisen, in all probability, like most A L G A. L. K. IDICTIONARY | OF MECHANICAL SCIENCE, 25 others, by such slow and imperceptible degrees, that were we in possession of all the writings of the ancients, it would perhaps be difficult to draw a line, so as to determine the precise com- mencement of the algebraic art. The analytical method of investigating problems must have suggested itself very early to mathematicians. Those unknown quantities which are now represented by letters, were in the infancy of this science pro- bably expressed by their names at full length, and every ope- ration performed upon them, as addition, subtraction, multi- plication, &c. were expressed in the same manner. . But it would soon be found, that in this way a useless and tiresome repetition of the same words would occur in the most simple problems, whence we may easily conceive, how the idea of expressing quantities by letters first arose, which was by sub- stituting the initial of the word for the word itself: the several operations were soon after represented in the same way ; and thus by successive improvements arose this noble and compre- hensive science, which in its present state does honour to the inventive genius of man,—Algebra is naturally divided into numeral, and specious or literal. - . Numeral ALG EBRA, is that which is chiefly concerned in the solution of numeral problems, and in which all the given quan- tities are expressed by numbers. e Specious or Literal ALG EBRA, is that commonly used by the moderns, in which all quantities, whether known or unknown, are expressed by general characters, as letters, &c. in conse- quence of which general designation, all the conclusions become universal theorems for performing every operation of a similar nature with that for which the investigation was instituted. Every figure or arithmetical character has a determinate and individual value; as, for example, the figure 4 always repre- sents one and the same number, namely, the collection of four units: algebraical characters, on the contrary, must be general, independent of any particular signification, and proper to represent all sorts of quantities, according to the nature of the questions to which they are applied: farther, they must be sim- ple, and easy to describe, so as not to be troublesome in ope- ration, or fatiguing to the memory. These advantages meet in the letters of the alphabet, which are, therefore, usually adopted to represent magnitudes in algebra. In algebraical inquiries, some quantities are assumed as known or given; and others are unknown and to be found out: the former are com- monly represented by the leading letters of the alphabet, a, b, c, d, &c.; the latter by the final letters, w, ac, y, z. Though it often tends to relieve the memory, if the initial letter of the subject under consideration be made use of, whether that be known or unknown: thus r may denote a radius, b a base, p a perpendicular, s a side, d density, m mass, &c. The charac- ters used to denote the operations are principally these : + signifies addition, and is named plus. — signifies subtraction, and is named minus. × denotes multiplication, and is named into. -- denotes division, and is named by. V the mark of radicality denotes the square. & the cube root. = equality, equal to proportion. Numbers are connected with the Algebraic symbols in two ways, viz.: 7a, a2, signifying 7 times ar, and the second power of a. The figure 7 before the w is called a co-efficient, and shews how often a is taken; the figure 2 on the shoulder of a is called an inder or exponent, and denotes the power of the letter it belongs to. If the exponent be a fraction as a', wº, it denotes the [T] root, or cube root of r. Like quantities are expressed by the same letters with the same indices, as, a, 6 a., 7 a ; unlike quantities consist of different letters, as, a and b, or 2 a and a”. Simple quantities are composed of one term only, as, a, b, 6ab, 7ar”, &c. Compound quantities consist of several terms, con- nected by the sign plus or minus; as a + b, 7aw — 3b, 3ab -- b – c, &c. Positive or affirmative quantities are such as have the sign + before them, as, + a, + 6ay. Negative quantities are those which have the sign — before them, as, – a, – 6xy. Like signs are all affirmative (+), or all negative ( – ). Unlike signs are composed of affirmative (+) and negative (—) signs. A binomial quantity consists of two terms, as, a + b : a trino- mial of three terms, as, a + b — b; and a quadrinomial of four, as a + b – c –H d, &c. . A residual quantity is a binomial, An which one of the terms is negative, as, a - b. A surd or irra- tional quantity has no exact root, as, Va, or Wa”, or abł. A rational quantity has no radical sign (V) or index annexed to it, as, a or ab. The reciprocal of any quantity is that quantity a . 1 d of it i b • T is +, all Ol O T, 1S Ta. —For the several operations in Algebra, as addition, multipli- cation, &c. see the several articles. ALGENEB, a fixed star of the second magnitude in the con- stellation Perseus. , ALGOL, a star of the third magnitude, in the same constellation. - ALIAS, in Law, a second or further writ issued from the courts of Westminster, after a capias, &c. has been sued out without effect. ALIEN, in Law, a foreigner, one not within the king's alle- giance. ALIENATION, the act of making over a man's property in lands, &c. to another. - ALIENATION, in Mortmain, bequeathing lands to a body politic, by the king's license, else the property becomes for- feited. ALIOTH, a star in the constellation of the Great Bear much used for finding the latitude at sea. - ALIQUOT Part, (from aliquotus, any number of times,) is such a part of a number as is contained in it a certain number of times, and may therefore be otherwise considered as a divisor, or rather the quotient arising from division. See Division. ALKALI, in Chemistry, a particular class of salts. The alkalis at present known are these,_soda, potass, ammonia, barytes, strontia, lime, and lithium. Potass, soda, and flint, make glass : potass, soda, and oil, make soap, &c. The alka- lis are incombustible, soluble in water, and possess an acrid urinous taste. They combine readily with acids, and precipitate from them the metals with which they had been previously combined. They change vegetable blues to green, red to violet, and yellow to brown. Potass and soda render oil miscible with water, and so form soap. Their peculiar crystallization when united with flint is obvious in glass.- Potash, a vegetable alkali, exists completely formed in the vegetable, or is produced during the operation of combustion. Potash readily combines with fat substances, and renders them soluble in water; these combinations form soap. Wine lees may be rendered almost entirely into alkali by combustion. This alkali is greenish, and is considered pure. The combus- tion of wine-stone also furnishes very pure alkali, but neutra- lized: it is known under the name of carbonate of potash, or salt of tartar. If potash and silex are fused together, the com- bination forms glass, but this product differs in its properties according to the respective quantities of silex and potash, of which it is composed.—Soda, or the mineral alkali, greatly resembles potash, and is obtained from the ashes of marine plants; as sea-weed, &c. The combination of soda, or potash, with oils or fat, forms soap ; the union with potash affords soft soap, and the combination of Soda with the same substances makes hard soap. Mottled soap is made by disposing the ley through the Soap, or by adding to it a quantity of solution of sulphate of iron, which, by its decomposition, deposits its oxide through the soap, and gives it a variegated appearance. In some manufactories, the black oxide of manganese is made use of for the same purpose. Yellow soap is made of tallow and resin with an alkali.-Ammonia, or the volatile alkali, is distinguished from the former alkalis by a very sharp pungent smell, and by its great volatility. It always appears either combined, or in the state of a liquid, (liquid ammonia,) or in the aërial form, and then it is called ammoniacal gas. Its compounds are solid only when it is combined with acids.- Barytes has never yet been found free from all combination. It may be obtained in a state of purity by the calcination of its carbonate or nitrate, which is the heaviest mineral known. For this reason, carbonate of barytes has been termed ponderous spar. To animals it is a deadly poison.—Strontia, found in the state of a carbonate, that is so say, combined with carbo- nic acid, in a vein of lead ore, at Strontia, in Argyleshire, in • H inverted, or unity divided by it, as 5 £6 VA L L A L T, DICTIONARY OF MECHANICAL SCIENCE: the western part of Scotland, is either of a bright green colour, or transparent and colourless.—Lime, called also calcareous earth, is now generally considered as an alkali, as it possesses the properties of that class of substances in a striking manner, its sparing solubility in water excepted. It is found very abundantly, though never pure, or in an uncombined state. It is always united to an acid, and very frequently to the carbonic acid, as in chalk, common limestone, marble, calcareous spar, &c. It is contained in the waters of the sea, is found in vege- tables, and is the base of the bones and shells of animals. Its combination with sulphuric acid forms sulphate of lime, gyp- sum, or plaster-of-paris. With fluoric acid it constitutes fluate of lime, or Derbyshire spar.—Lithia. For the discovery of the new fixed alkali, lithia, having for its base a new metal, (lithium,) we are indebted to M. Arfvresdon, who obtained it from petalite, a mineral which, by his analysis, was found to be composed of silica 80 parts, alumina 17, and the new alkali 3 parts. It is extracted from the petalite by calcining the latter, in powder, with carbonate of barytes, separating the earths, and obtaining the alkali combined with an acid. Its combinations with acids are, generally, very fusible. The sul- phate and muriate liquefy below a red heat; the carbonate, when red-hot, acting violently on the platinum crucible. The former crystallizes readily, and retains no water of crystalliza- tion; nor is their solution precipitable by muriate of platinum, or by tartaric acid. The nitrate crystallizes in rhomboids, and attracts moisture; the muriate is highly deliquescent; the carbonate is with difficulty soluble in water; and when evapo- rated, the salt crystallizes in slender prisms; it has a greater capacity for saturating the acids than even magnesia. Alkalis are substances which have a great affinity for the acids; and the substances formed by the union of an acid and an alkali are called neutral salts, which have neither acid nor alkaline properties. East Indies. ALLEGIANCE, in Law, the tie or ligamen which binds the subject to the king, in return for that protection which the king affords the subject. - ALLERION, in Heraldry, an eagle without beak or feet, having nothing perfect but the wings. Aiiigation, in Arithmetic," is a rule by which such questions are resolved as relate to the mixing of divers mer- chandises, metals, simples, liquors, drugs, &c. of unequal prices, so as to find how much of each must be taken, accord- ing to the question: and Alligation is either medial or alter- Alligation Medial is, when the price and quantities of several simples are given to be mixed, to find the mean price of Rule:–As the whole composition is to its total value, so is any part of the composition to its mean price. nate. that mixture. Proof:—Find the value of the whole mixture at the mean rate, their respective prices, the work is right. Evample 1. bushel of this mixture ? 20 × 5 – 100 36 × 3 – 108 40 × 2 - 80 96 288 Erumple 2. A grocer mixes 30 lb of currants at 4d. per Ib, with 10 lbs of other currants 30 at 4d. . . . 120 at 6d. per lb.--what is the value 10 at 6d. ... 60 per Ib of this mixture ? 40 As 96 : 288 . . . ; 3. Ams. 3s. ) iso(4 Ans. Alligation. Alternate is when the prices of several things are given, to find such quantities of them to make a mixture, that propounded.—In ordering the rates and may bear a price given price, observe, 1 Place them one under the other, and the :- —i. prºpounded price, or mean rate, at the left-hand X 22.T. of them, thus, 28 º A farmer mixed 20 busheſs of wheat, at 5s. per bushel, and 36 barrels of rye, at 3s. per bushel, with 40 bushels . of barley, at 2s. per bushel.—I desire to know the worth of a | - 2. Link the several rates together by 2 and 2; always observing to join a greater and a less than the mean. 3. Against each extreme, place the difference of the mean and its yoke-fellow.—When the price of the several simples and the mean rate are given without any quantity, to find how much of each simple is required to compose the mixture.—Rule. Take the difference between each price and the mean rate, and set them alternately, they will be the answer required.—Proof. By Alligation Medial. - - - Example. A vintner would mix four sorts of wine toge- ther, of 18d. 20a, 24d. and 28d. per quart—what quantity of each must he take to sell the mixture at 22d. per quart 2 - Proof. - Answer. Proof. Or thus: . 18 2 of 18d. - 36d. 18 16 of 18d. – 108tl. 2220– 6 of 296 = 129 2220–1 |2 of 296 = 40 24—|—|4 of 24d. – 96 24—l 2 of 24d. – 48 28—' 2 of 28d. - 56 28 4 of 28d. - 112 - 14, )308 14 )308 22d. 22d. Note.—Questions in this rule admit of a great variety of answers, according to the manner of linking them. Alligation Partial is when the price of all the simples, the quantity of but one of them, and the mean rate, are given, to find the several quantities of the rest in proportion to that given.—Rule. Take the difference between each price and the mean rate as before. Then, As the difference of that simple, whose quantity is given, is to the rest of the difference severally, So is the quantity given, to the several quantities required. Example. A tobacconist being determined to mix 20 lb. of tobacco, at 15d. per lb. with others at iód, per lb. 18d. per lb. - | and 22d. per lb.-how many pounds of each sort must he take ALLEGEAS, a cotton or flax stuff, manufactured in the - to make one pound of that mixture worth 17d.? Answer. Proof. - 15 15 20 lb. at 15q. = 300tl. As 5 : 1 : : 20 : 4 - 1716– I 4 lb. at 16d. – 64d. As 5 : 1 : : 20 : 4 + 18— 1 4 lb. at 180. = 72d. AS 5 : 2 : : 20 : 8 22 |2 8 lb. at 22d. - 176d. - 36 lb. : 61.2 : : 1 lb. : 17d. - *- Alligation Total, is when the price of each simple, the quan- tity to be compounded, and the mean rate, are given, to find how much of each sort will make the quantity.—Rule. Take the difference between each price, and the mean rate, as before: then, As the sum of the differences is to each particular difference, so is the quantity given, to the quantity required. ' Example. A grocer has four sorts of sugar, viz. 12d. 10d. tº ſe º a , - - - tº . tº | 6d. and 4d. per lb. and would make a composition of 144 lb. and if it agrees with the total value of the several quantities at worth 8d. per lb.-I desire to know what quantity of each he must take 7 - Answer. Proof. ... • 12 4 48 at 12d. – 576 As 12 : 4 : : 144 : 48 slº– 2 24 at 10d. – 240 As 12 : 2 : : 144 : 24 6– 2 24 at 6d. E 144 - . . . . 4 — ..] 4 48 at 4d. - 192 12 144 )1152(8d. ALLITERATION , a rhetorical ornament, which consists of the repetition of the same letter at certain intervals; as, “ Weave the Warp, and Weave the Woof.” “Fields.ever Fresh, and Groves for ever Green.” - “ Mountains, ye Mourn in vain, Modred whose Magic song.” - ALLIUM, garlic, a plant with a bulbous root, much used both as seasoning and food. When bruised and applied to the skin. it causes inflammation and raises blisters. In cases of dropsy, asthmas, and agues, it is excellent, administered as a bolus, or | made into pills; or pounded in a mortar, and a spoonful | taken in a glass of milk. Its smell is good in female nervous disorders. Its juice makes the strongest cement for broken glass and china: placed near the haunts of grubs, slugs, &c. in the garden, it drives these vermin away. - • . A L Q. A L T DICTIONARY OF MECHANICAL SCIENCE, , ALLOY signifies the production of a baser metal mixed with a finer one. In Chemistry, we apply the term to the union of different combinations of metallic matter; as, bronze, tombac, brass, white copper, &c. . . ALLUVION, in Law, the gradual increase of land sea-shore, or on banks of rivers. . ALMAGEST, the name of a celebrated work composed by Ptolemy, and consisting of 13 books; being a collection of many of the observations and problems of the ancients, relating both to geometry and astronomy. It contains a catalogue of the fixed stars, with their places; besides numerous records of eclipses, the motions of the planets, &c.; being the first work of the kind which has been transmitted to us, and is therefore very valuable to astronomers. - - - - ALMANACK, (said to be formed of the Arabic particle al, and manah, to count,) a calendar or table, in which are noted down all the most remarkable phenomena of the heavenly bodies for the ensuing year; such as eclipses, conjunctions and oppositions of the planets, risings and settings of the sun and moon, &c.; with the return of feasts and fasts. Nautical ALMAN ACK and Astronomical Ephemeris, is a national almanack, begun in 1767, under the direction, and by the advice, of the astronomer royal, the late Dr. Maskelyne. This almanac, computed a few years forward, for the convenience of ships going out upon long voyages, for which it is highly useful, contains, besides most things essential to general use, and which are found in other almanacks, many new and important particulars, as, the distance of the moon from the sun and fixed stars, computed to the meridian of Greenwich, for every three along the hours of time, for the purpose of computing the longitude at . sea.—The astronomical day is here used, which begins at noon, and is twelve hours later than the civil day, which is counted up to 24 hours; or from sun-rise in the morning to Sun-setting at night, and from sun-setting at night till sun-rise in the morning. The Construction of ALMANACs is extremely easy, if you strip them of all the absurd astrology with which such as Moore's, &c. may be crammed. The first thing to be done is, to com- pute the sun's and moon's place for each day of the year, or it may be taken from some ephemerides, and entered into the almanac. the calendar into weeks. Next find the dominical letter, and by it distribute Then, having computed the time of Easter, by it fit the other moveable feasts; adding the im- moveable ones, with the names of the martyrs, the rising aud setting of each luminary, the length of the day and night, the aspects of the planets, the phases of the moon, and the sun's entrance into the cardinal points of the ecliptic; i. e. the two equinoxes and the two solstices. ALMöND, the fruit of the almond-tree, a soft and pleasant- | Almonds are flavoured kernel, contained in a flattish nut. used in confectionary and cookery; they are also eaten with raisins in desserts after dinner, but they should be well chewed, as, like all nuts, every piece you swallow entire is indigestible. The oil of almonds is much used ; their milk is formed of pounded almonds, loaf sugar, and water, well mixed together, and is much used in medicine. ALMONDs, To burn. Put two pounds of loaf sugar and two pounds of almonds into a stew-pan with a pint of water, and let them boil over a clear fire till you hear the almonds crack ; } then take them off, and stir them till they are quite dry. Then put them into a wire sieve, and sift all the sugar from them. Put the vinegar into the pan again, with a little water, and boil : it; put four spoonsful of scraped cochineal to the sugar, to colour it. Put the almonds into a pan; keep stirring them till they are quite dry : then put them into a glass, and they will keep for twelve months. ...ALMUCANTARS, ALMACANTARs, from the Arabic almocan- tharat, are circles parallel to the horizon, conceived to pass through every degree of the meridian ; being the same as the parallels of latitude.—ALMUCANTAR’s Staff, was formerly used at Sea, for observing the sun's amplitude at rising or setting. ALOE, a large plant, with fleshy, spinous leaves, from the centre of which, magnificent blossoms rise on stems, some twenty feet, when the tree is in a vigorous state. In Spain, where this plant. is cultivated in hedge-rows, the leaves are used as scouring-paper, or their essence as soap, for it will lather in salt or fresh water. - - and the station from which the measure is to be taken. º, ALOPECIA, a falling off of the hair from the head, &c. either from some defect in the nutritious juices, or by its vici- ous quality corroding the roots. A fresh-cut onion rubbed on the place till it be red and itch, is said to cure baldness. ALOPECURUS, foxtail grass; one of the most productive plants of the tribe: cattle are fond of it; it grows well in moist situations, and being very early, may be cut by the middle of May. Two bushels of seed will sow an acre, with about six teen pounds of clover. - - ALPHABET, the several letters of a language, as A, B, C, &c. a, {3, Y, 6. - ALPHAENIX, in Medicine, the trivial name of white barley sugar. Perhaps the name makes it valuable ! The sugar is, however, good for colds, and may be easily made by boiling common Sugar till it becomes easy to crack, when you should pour it on a miarble slab, greased with almond oil, and then mould it into any figures you please. ALPHONSINE TABLEs, are astronomical tables, compiled by order of Alphonsus, king of Castile. - ALPHONSIN, in Surgery, an instrument for extracting bal- lets out of gun-shot wounds. - ALSINE, chickweed, the leaves of which every night fold themselves up in pairs, to protect the rudiments of new shoots; thus affording a remarkable instance of the sleep of plants. ALT, in Music, the high notes of the scale. - ALTAR, fig. 51, a place upon which sacrifices were anciently offered to some deity. The altars of pagans were originally of turf, but latterly of marble, stone, &c. These altars were .decorated with sculptures of the respective gods to which they were dedicated. Altars were doubtless as ancient as sacrifices, Gen. chap. Iv. The altar Jacob set up at Bethel was merely a t-nºmº stone; that of Gideon, a stone before his house; but, under Moses, the people of Israel had their altar of incense, that of burnt-offering, and the altar or table for the shewbread. ... ALTITUDE, in Astronomy, the distance of a star from the horizon ; which may be either true or apparent, according as it is taken from the true or apparent horizon. - ALVEARIUM, a bee-hive ; also the concha, or hollow of the outer ear. Alveolus, the cells of a bee-hive. In Anatomy, the sockets in the jaws, wherein the teeth are fixed. ALUM, a clear transparent saline matter, of a very austere and astringent nature, useful in medicine and the arts, ALTERNATION, or PERMUtAtion of quantities or things, is the varying or changing the order of them. See PERMUTATION. ALTIMETRY, the art of taking or measuring altitudes or heights, accessible or inaccessible, perpendicular or oblique. ALTITUDE, in Geometry, the third dimension of a body, considered with regard to its elevation above the plane of its base. , ALTITUDE of a Figure, is the distance of its vertex from its base, or the length of a perpendicular let fall from the vertex to the base. Altitudes are divided into accessible and inacces- sible. Accessible Altitude of an object, is that whose base we can have access to, so as to measure the distance between it Inac- cessible Altitude, is when the base of the object cannot be 28 A L T A LT DICTIONARY or MECHANICAL science. approached.—There are several methods of measuring the height or altitude of bodies, viz. by Geometry, Trigonometry, by Optical Reflection, by means of the Barometer, &c. The instru- ments commonly used in measuring altitudes, are, the Geome- trical Square, Quadrant, Theodolite, and Harris's Telescope, a description of each of which will be found under the respec- tive articles. . Prob. 1. To measure an accessible or inaccessible Altitude geo- metrically.—Under this head are included all those cases, in which the calculation depends upon pure geometrical prin- ciples, and particularly on the similarity of triangles, of which we propose to give an illustration in the following examples: Let A B represent an ob- ject, of which the altitude * qu }. required. Being pro- Fig.52. ...~" |riſ vided with two rods, …” | ëll: or staves, of different 2." * t i lengths, plant the longest - ... |||ſ|| of them, as FC, at a cer- £º. C. | | ºffſ: tain measured distance …” f from the base of the ob- ºf Ti, Tº A ject. Then, at a farther distance, plant the second or shorter staff E D, in such a man- ner that the tops of the two, E and F, may be in a line with the top of the tower B. Then having measured the distance ID, as also the length ED, we shall have by similar triangles, as . ID : E D : : I A : A B ; that is, by multiplying the second and third terms, and dividing by the first, we shall have the whole altitude of the tower B.A.: that is, B A = | A x_* D. I D For example, suppose I A = 100 feet, ID = 8 feet, and ED = 4 feet, being the height of the staff; then B A = 100 × 4– 50 feet, - 8 the altitude of the tower. When the object is inaccessible, two such operations as the above must be resorted to. Prob. 2. To measure accessible or inaccessible Altitudes, by means of their Sha- dows.—At any time tº Zºº. Ö3. 23° when the sun shines, 9. 22' planta; rod a b, per- _^ 2. Aſ pendicularly at a, and b 2. 2- A measure the length of 2% !-- 2' .* 2^ .." its shadow, and im- 2'. mediately after mea- 37 GT3 C’ sure the shadow of the proposed object A. B. d Then, by similar triangles, ca : b a . : C A : ** x C A = A B, C (!, * the altitude required. If the object be inaccessible, but still such that the difference of the lengths of its shadows, ca, ća, taken at two different times, can be ascertained, the altitudé may be found nearly the same as in the last example. Prob. 3. To measure accessible or inaccessible objects, by means of Optical Reflection.--Place a mirror, or other reflecting sur- face, horizontally in the plane of the figure's base, as at C, and when the object is ac- - cessible, measure the 22:15 distance C. A. Now Fig.54. 2.3% retire back in the di- …?" rection A C to D, till ..”.” the eye observes the Pº 22° 2' top of the object exact- $, S×" I-A I- ly in the centre of the -: mirror, which, for the greater degree of accuracy, may be marked by a line across it. Then having measured the distance D C, and ascertained the height of the eye of the observer, it will be, from the known laws of reflection, as D C : DE : : C A : pºca the altitude of the object required. When the object is inac- cessible, that is, when the distance C A cannot be measured, two such operations as that above must be employed. D FTE = A B, ; Prob. 4. To measure an accessible or inaceessible object, by the Geometrical Square or Quadrant. See QUADRANT. Having fixed the instrument at any place º C, turn the square about the centre of motion D, till the top of the object B is perceived in the direc- * tion of the sights placed on the , _º i. Ps C. side of the square DE, and note the number of divisions cut off 4 the other side by the plumb line -: EG ; then having measured the distance C A, we have, by similar triangles, as E F : F G : : C A or D H . *****= BH, to which adding the height of the observer's eye, DC, we shall have gapºre + D C = A B, the altitude sought. Prob. 5. To measure an accessible object trigonometrically.— Let A B be the object of which the altitude is .*115 required. At any convenient station C, with a quadrant, theodolite, or other graduated instrument, measure the angle of elevation A C B ; then, having also measured the dis- tance CA, we have, from the elementary prin- ciples of trigonometry, as - Rad. : A C : : tan. 2: A C B : A B, - *- the altitude required; or, by logarithms, Log. A B = log. A C + log, tan. A C B — log. rad. Suppose, for example, the distance A C = 340 feet, and the angle of the elevation AC B = 34° 30'; then, by the above formula, Log. A C, or log. 340 – 2:5314789 Log. tan. 34° 30'.... – 9.8371343 Fig.56. A 12:3686132/ Log. radius 10°0000000 © e º 'º e s e e º e Log. B A – 233.67 . . 2:3686132 Prob. 6. To measure an inaccessible object by two stations.— - 13 Let A B be the object of which the altitude is required. Take the angles of elevation at the two stations D and C, & mea- sº Surc the dis- A tance between them. The angle D B C – the difference of the two measured angles BCA and BDA, (Euclid. prop. 16, book 1,) which angle therefore becomes known. And by trigonometry, as sin. D B c : D C ; ; sin. CD B : P9 × slº. 92% *†† =CB. Again, as radius : C B : : sin. ACB : C B *# A C B — B A, the altitude required. Or substituting, in the second expression, the value of C B, we have IB A = D C. × sin. C D B. × sin. A C B. *º Rad. × sin. D B C. Or by Logarithms.--From the sum of the logarithms of the terms in the numerator, subtract the sum of those in the deno- minator, and the remainder will be the logarithm of the required altitude B.A. frnmediately connected with angles of altitude, or horizontal angles, is the consideration of Mr. Harris's Micrometrical and Double-image Telescope and Coming-up Glass. This instru- ment is particularly useful at sea, or in situations when it is either difficult or inconvenient to keep an instrument in a steady position. Hence it becomes an excellent coming-up glass for ascertaining whether a ship is approaching to, or receding from, the observer. In practical astronomy it is of very extensive use, and as the minutes and seconds are, in some of the instru- ments, engraved on the scale, the angle is found without the A. L T A L T 29 JDICTIONARY OF MECHANICAL SCIENCE. trouble of reduction. The great length of the scale too, which is generally equal to the focal length of the first object-glass, renders the use of the instru- ment very simple. And we give this a place here, because, under the word Telescope, we shall have enough to say on the instruments, of other opticians, which are purely astronomical. Section I. Description, of the Telescope.—This valuable instrument, fig. 58, is divided into four parts, or drawers, of which the outer one contains a fixed object-glass at A. At C in the part CD is a moveable object-glass, which by pushing the parts BC and CD quite in, is brought into contact with the fixed object-glass at A. . In this position of the drawers, distinct vision is procured by pulling out the eye-piece DE; and the magnifying power of the instrument is at its minimum or lowest degree. By pulling out the drawer CD, and afterwards the drawer BC, the magnifying power of the glass is made to increase ; and when both these parts are quite drawn out, and distinct vision procured by re-adjusting the eye-piece DE, (which it will be found necessary to do every time that the position 90 of either of the drawers is altered,) the magnify- ing power of the glass is at its maximum or greatest degree. In this position of the drawers two scales will be perceived thereupon; one adapted to the single object-glass above mentioned, and the other to a divided object-glass, of which a particular description will be found in the last section. By looking through the telescope, or at fig. 59, two parallel points a, b, are seen pro- jecting into the field of view, as also a pair of fibres, m m, op, which, with the object-glass, are essential parts of the instrument. Ror when it is required to mea- sure the angle subtended by any . . e two points of an object, in order to ascertain its dis- tance from the observer, it is necessary that these points should be brought to coincide exactly with the steel pins, which appear as fixed points in the field of view, as before observed: which may be thus effected :—Having chosen a sta- tion which you think convenient for the observation, and two conspicuous points in the object, shut the drawers BC, CD quite in, and procure distinct vision of the points in the object, by pulling out the eye-piece DE: the points in the object will generally occupy a less space than that between the steel pins. In order that they should coincide, first draw out the part CD until they are found to do so exactly; and the milled ring at C will cut the scale at the minutes, and part of a minute, which the angle subtending the points contain. If the points do not coincide when the part CD is quite drawn out, then draw out BC until coincidence is procured; obtaining distinct vision as you proceed, and the milled ring at B will shew you the angle as before. If, when the drawers are both shut in, the points of the object occupy a greater space than the steel pins, you are too near the object, and must therefore choose two more convenient points upon it, or a more convenient station by receding from it. If, on the contrary, when the drawers are quite out, the points of the object occupy a less space than the steel pins, you are too remote from the object, and must choose either two more convenient points thereon, or a more proximate station. Observe, the drawer BC is in nowise to be touched, until C D is first quite drawn out. Section II. To ascertain the distance of an object either at sea or on land, by two angles and a base between them.—When you are approaching the object, as will be oftentimes the case at sea, the first angle should be obtained when the drawers are nearly, or quite pulled out, because the angle will be increas- ing. But if you are receding, the angle for the contrary reason should be obtained when the object-glasses are but little apart. Let the two points of the object be called D and E, and the object C, (fig. 60,) and let the place of the first observa- tion be called B, at which the points of the object coincide #58 F. H *H, 18t Fig.59. with the steel pins a, b, when the object-glasses are nearly in contact; in this case, measure a receding base to A, which should be in a straight line from the object, and not less than ; part of its supposed distance, reckoning from the object- glass of the telescope; and at this second station, again mea- IC) C E sure the angle subtending the points of the object. Then to find the less distance BC ;—Multiply the base by the less angle, divide the product by the difference of the angles. The quo- tient will be the less distance. To which adding the base, you will, if it be wanted, obtain the greater distance. If, by reason of the distance of the object, the steel pins cannot be conve- niently used, the parallel fibres may be taken instead, as the ratio of the angles, determined as above, will answer the same purpose as the angles themselves, when obtained from the coin- cidence of the steel points a, b, with D, E, in the object. Example 1.—Wanting to know my distance from a fortifica- tion, I found the angle subtended by two prominent points thereupon to be 180 minutes, then receding 150 yards in a straight line, I again found the angle subtending these points was 140 minutes.—Now to find the distances : We have the greater angles 180', less angle 140, their difference 40'. Length of the base....... . 150 yards. Less angle. . . . . . . . . . . . . . . . 140 q 6000 150 Difference of angles...4.0)2100,0 Less distance. . . . . . . ... .. 525 yards. Add the base. . . . . . . . . . . . . 150 f - Greater Distance. ... . . . . . . 675 yards. * I’vample 2.—Standing in shore by night towards the Lizard, I observed that the angle subtending the two lights was 40'; then standing in a direct course 1% mile nearer per log. I again observed the angle to be 46,-required my distance from the light at the place of the last observation. Here greater angle 46, less angle 40, their difference 6 minutes. - Length of the base'............. # Less angle ... . . . . . . . . . . . . . . . . . . 40 § Difference of angles divisor..... 6)60 Less distance ...... . . . . . . . . . . . . 10 miles required Add the base . . . . . . . . . . . . . . . . . . 1} Greater distance................ 11% Section III.—To obtain the distance of a given point from any place, when the inequalities of the ground, or proximity to an enemy’s guns, render it impracticable to measure a base from that point. Let M be the given point, and C the place whose distance is wanted, (see fig 61.) Let also a, b, be two con- tº. § 2 ** == rº • spicuous points upon that place. Take two stations, A and B, 30 A L 'T .* A LT BICTIONARY OF MECHANICAL SCIENCE. beyond the reach of the guns; but in the same straight line with MC, and by measuring the base AB and the angles abb. aAb, find as in the last section one whole distance AC. Then at the point M take the angle a M b, so will the distance MC be a fourth proportional to the angles and base, that is, angle a Mb: angle a Ab: A C : M C. To find M C therefore, multi- ply the greater distance by the angle measured at the greater distance; divide the product by the angle at the given point, and the quotient will be the distance required. - Example.—Wanting to know the distance of a point M, fig. 61, from a tower C, and circumstances preventing my mea- suring a base, I took two remote stations, A and B, but in the same vertical plane with MC, and distant from each other 250 yards, at which I measured the angles A and B, subtended by two conspicuous points a, b, upon the tower: the angle a A. b = 60', and a B b = 92'; and at M, I measured the angle a Mb = 205, required the distance: First angle B = 92, and A = 60 their diff. = 32'; and angle B wº- base 719 yards A C by the last section; then angle M, angle A :: A C : M C ; or 205': 60': : 719 :210,4 yards. - Or as angle M . . . . 205' arith. com. log. 7,688.25 Is to angle A...... 60' . log. . . . . . . . . 1,77815 So is A.C. ........ 719 log. ..... . . . 2,85673 To M. C. . . . . . . . 2104 log.......2,32313 Working by logarithms, which in general will be found the most expeditious method. * Section Iv. To measure the height of an accessible object.—Let B.A (fig. 62.) be an accessible object; then from a point B, as near as possible to the vertical line C B A, measure the angle a B b, subtended by two conspicuous points at the summit of the object; measure also the angle a C b, subtended by the same —$ A. B C D points, as seen from another station C, and measure the base C B. Then to find the perpendicular. Square the greater and less angles, take the difference of the squares, and the square root of this difference. Multiply the greater angle by the base, and divide the product by the square root just found ; the quotient will be the perpendicular height required. Or, if the Hypothenuse A C be wanted: Multiply the less angle by the base for a dividend, and divide by the square root above, and the quotient will be the answer. Example:—Wanting to know the height of a tower, (fig. 62,) I measure from a point B near its base, the angle subtended by two points a and bat its summit, which was 150 m. I then mea- sured 56 yards to a point C, and again took the angle between the points, and found it 180 minutes. Here the greater angle. ... 180 The less angle. ... 105 180 105 14400 525 180 1050 Sqr. of Gr. angle. . . . . . . . . . 32400 11025 Sqr. of less angle . . . . . . . . . 11025 Diff. of square. . . . . . . . . . . . 21375 (146, 2 root - 1 Greater angle..... 180 Base . . . . . . . . . . . . 56 24)113 *===sºme 96 1080 g 900 286)1775 - 1716 146,2)10080 2922)5900 Perpen. 68,95 5844 gº-- *-* 56, &c. It is obvious that this question, even in its most simple state, may be more readily performed by logarithms. - Thus, greater angle........ 180 Log. 2,25627. 2 ... Square of gr. angle........ 32400 4,51054 Square of less. angle ... ... 11025 *-ºpe Diff. of Squares....... º . 21.375 Less. angle. . . . . . © º ºs ºs e º ſº e e 105 Log. *ng 11025 Log. 4,04238 . Diff of Square Log......2)4,32990 Square root Log. . . . . . . . 2,16495 ar. Co. log. 7,83505 Logarithm of Gr. angle. . . . . . . . . . 2,25527 Logarithm of Base. . . . . . . . . . . . . . 1,748.19 The perpendicular required 68.95 Log. 1,83851 Section V. To ascertain the distance of a known magnitude.— Let the distance between two points D and E (fig. 60) of a distant object be known, then by choosing a station at B, so situated that the line joining these points may be at right angles to the axis of the telescope, and measuring the angle subtending these points as seen from B, we have, for ascer- taining the distance of B, from the object, the following Trigo- nometrical Theorem: Tangent angle B: DE:: radius: the distance. Or to the Cotangent of angle B add the logarithm of D B; the sum, rejecting 10 in the index, will be the logarithm of the distance. - Example.—Seeing a ship, the height of whose main-top-gal- lant mast head I take to be 150 feet, or 50 yards above the water's edge, I measure the angle subtended by these points, which is 43 min.--what is my distance from her? " * Here angle B...... 43' Log. Cotangent 11,90278 Dist. of points...... 50 Log. . . . . . . * * * * * 1,69897 Distance. ... . . . . . . . 3997 Log. ....... . . . . . 3,60 175 - So my distance from the ship is 3997 yards, or 2 miles nearly. Note.—After any given interval of time you may again observe whether the points are still in coincidence: if they are, the angle remaining unaltered shews clearly, that you are both sailing at the same rate if they do not still coincide ; but the steel pins occupy a greater space than the points of the ship, the angle is decreasing, and you are dropping astern ; but if the points of the ship occupy a greater space, you are coming up ; and may, by another observation, determine at what rate. It may be necessary here to observe, that any two points may be taken for the above purposes, provided that their distance from each other is known, and their position such, that a line joining them may be at right angles to the axis of the tele- scope: for which reason the points upon the masts are to be preferred to those upon the yards, being less liable to vary their position. - - Section v1.-It has been hitherto supposed that the single object-glass, with the steel pins, has been used in the obser- vation; these however are liable to an inconvenience at sea; which, although it will be overcome by practice, may not here be overlooked: for when the two points of an object are brought into contact with the steel pins, the slightest motion or tremor of the hand will again displace them, and thereby render the observation, to a beginner especially, exceedingly tedious. These inconveniences may however be entirely obviated, by substituting the divided object-glass for the single moveable one at C in the instrument; and of which the following description is submitted to notice:—The divided object-glass consists of two semilenses, whose centres are invariably distant; when it is used, by looking through the telescope, two images of the object will appear upon the field of view, which by turning the telescope gently upon its axis, will appear to revolve about each other, being quite separate, ſae， .， ſae · = ！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！ ∞· ………o'er…wºpnu ſºuor |- .|- |-， º ---- …|- |----- №. ſaenaeae ， ſi ſil|||||||| __-----------------~~~~ ~~~~ （7） …………………….----－-- ir ar iſ ſaevae ººrſ 7（7）， ºrº , ， , ， ， º （±√（√≠º |- ſaer . ---- ---- ---- ---- | | A. L. T A M E DIC, TIONARY OF MECHANICAL SCIENCE, 31. if the object does not occupy more than one-third of the field of view ; but, if otherwise, the images will overlap each other in a greater or less degree. Now, suppose the object A CBD, fig. 63, to be that under observation: then, if it be required to measure the angle subtended by the part A B of the object; first draw out CD, and afterwards, if necessary, the part BC, until the points a and b of one image exactly coincide with their corre- sponding point A and B of the other; and the index at C or B will point out the measure of the angle subtended by these points, upon the scale for the di- vided object-glass. If it were required to measure the angle subtended by the - points B and D of the object, it would be evidently necessary to adjust the drawers, until the point d coincided with its cor- responding point D. It will be found, that the images have different degrees of distinctions in different parts of the field; but it will be easy to make any part of an image more distinct than another, by changing its place in the field of view, and it will contribute to the accuracy of the observation, to bring the part of the image where the contact is to be observed, into the centre of the field, it being the part where the points of contact will be most distinctly seen. As a coming-up glass, the divided object-glass possesses an eminent superiority oyer the single one, by reason of the steadiness with which the observation may be made : for any two points being brought into contact, neither the tremors of the hand, nor even the motion of thc vessel, will displace them; its use may be illustrated as fol- lows: When a vessel is seen at a distance, it subtends a cer- tain angle at the eye of the observer; if the distance increases, the angle will, of course, proportionally diminish, and the con- trary. Now, if the vessel be viewed through the double-image telescope, and if the drawers be adjusted until the two images of the whole, or a part of the vessel, be brought into contact; the index will cut the scale in the angle subtended by the whole, or that part. If the images continue in contact, the distance of the vessel must have remained the same ; but if the images have separated from each other, the vessel must be receding from the observer, and the proportion of the distances may be found by again bringing the images into contact, finding thereby the angle "anew, and thence, by the 2d or 5th section, the dis- tance at the time of each observation. It may be also observed, that the object, or portion of an object, whose angle is to be measured by means of the double-image telescope, should be chosen as luminous as possible ; or, when it can be obtained, it should be a dark object with a light ground, such as the top of a building with a sky behind it: and in measuring inaccessible distances, as by section 2, the two images of the object DE should appear separate, but as near as possible, when the observer is at B, and when the object-glass and semi-lenses are in contact.—To facilitate the observation, this instrument is sometimes constructed with one drawer instead of the two, Tö C, CD, which, with the eye-piece, is adjusted by means of a rack and pinion upon each, the telescope being supported upon a stand; and when it is intended to change the object-glasses in the instrument thus constructed, it will be necessary, in order to come at the moveable object-glass, to screw off the top part of the instrument about 4 inches below the principal object. glass, having first adjusted the drawer quite in. And to cor- rect any variation which may occur in the sight of different observers, an adjustment to the stop is fixed upon the pipe containing the two first eye-glasses, by moving which, until the points and fibres are seen the most distinctly, the instrument will be adjusted to the particular eye of the observer.—We have here given a brief description of this valuable instrument, its uses and qualities, and trust, that upon trial, it will be found to exceed, rather than fall short of, the properties attri- buted to it. The examples which are introduced in the diffe- rent sections for the purpose of illustration, as well as the rules for working them, are applicable to either the single or divided image glass; and the principles upon which these rules, as well as the instrument itself, are constructed, are demonstrated at large in Dr. Brewster's Treatise upon New Optical and Philo- sophical Instruments. - Fºy, 63. Analogous to the foregoing, is the Micrometrical Telescope, which possesses all the advantages of the common telescope; is of great use for military and naval purposes, and likewise in surveying, and practical astronomy. The object of it is to mea- sure angles and distances, which it does with great facility and accuracy. From the nature of its construction, it has also the properties of an excellent microscope. This ingenious instrument, being formed with sliding tubes, is very portable and convenient, and will be found extremely useful to military gentlemen and others, who may wish to ascertain distances without a more cumbersome apparatus.-Those of our readers who already possess achromatic telescopes, may have them converted into this instrument at a trifling expense. ALYSSUM, madwort, a plant which was believed to have the property of curing madness. - AMABYR, an old British word, signifies, “the price of vir- ginity,” and expresses a barbarous custom which formerly pre- vailed in several parts of England and Wales, being a sum of money paid to the lord, when a maid was married within his lordship. 8 - AMADOW, the pyrotechnical sponge, a kind of black tin- der, made of a species of fungus or mushroom that grows upon the bark of trees in Germany. AMALG AM, mercury united with some metal. AMAUROSIS, a deprivation of sight, the eye remaining fair, and seemingly unaffected. - - AMBE, an instrument used by surgeons for reducing dislo- cated bones. - - - AMBER, a bituminous substance, highly electric, and much used in medicine and the arts. - AMBERGRIS, or Gray Amber, is found swimming in the Atlantic; on the coast of Brazil; in the East Indian archi- pelago, &c. and sometimes in the belly of the spermaceti whale. AMBIENT, a term applied to fluids that encompass others on all sides, as the air, a flame, &c. AMIBIT, in Geometry, the perimeter of any figure. AMBLE, the pace of a horse when his two legs on one side move at the same time. a. . . . . AMBUSCADE, a place where soldiers may lie concealed till they find an opportunity to surprise the enemy. AMERCEMENT, in Law, a pecuniary punishment, imposed on offenders at the mercy of the court. | AMERICA, the largest of the four quarters of the globe, extends from the 56th degree of south latitude to the unknown regions within the arctic circle, and from the 55th to the 165th degree of west longitude. Its length is nearly 10,000 miles, and its medial breadth about 2000. America was discovered by Christoval Colon, (or, as the Latin writers of the time call him, Christopher Columbus,) in four successive voyages: on the 12th of October, 1492, he discovered the isie of San Salvador; in 1493, the Caribbee Islands; in 1498, the continent adjacent to the Orinoco ; and in 1502, a great part of the continent around Porto Bello. Amerigo Vespucci, a Florentine, and a man of science, who accompanied Colon, published the first account of the New World, and thus gave it his own name corrupted into America.—America is divided into two parts, called North and South; and these are again subdivided into separate king- doms and states. - - - No RTH AMERICA is bounded on the north by the unexplored Arctic regions; on the west, by the Pacific Ocean and Beh- ring's Strait; on the south, by the Gulf of Mexico; and on the east, by the Atlantic Ocean; that is to say, from 73° north lati- tude, to 729 north latitude; or 644°, being 3870 geographical miles; and from 550 to 165° west longitude, or 110°, being 3300 geographical miles, taking the number of miles at thirty in a degree of longitude at latitude 60°. The climate is very various; but in general, summer's heat and winter's cold are more intense than in most parts of the continents of Europe and Asia. The centre of North America is a vast fertile plain, watered by many rivers. The seas adjacent to North America are Baffin's Bay, Hudson's Bay, the gulfs of California and Mexico, and the St. Lawrence. The lakes are, Superior, Michigan, Huron, and Slave lake, between Canada and the United States. The rivers are, the St. Lawrence, the Missouri or Mississippi, Rio-Bravo, the Ohio, Red-River, and the Mackenzie. The mountains are, the Stony Mountains, the Apalachian Chain, the Iron and White 32 A M E. A M E pICTIONARY OF MECHANICAL SCIENCE. Oak Mountains. These ridges are usually marked on good * maps. - South AMeRICA extends along 66° of latitude, or 3960 geogra- phical miles; and its breadth is 48°, or 2880 geographical miles, reckoning from Cape Blanco in the west, to Cape St. Roque in the east. Many parts of this vast continent are aboriginal and impenetrable forests, vast saline plains, regions flooded by inundations; and from the summits of the Andes, covered with eternal snow, to the torrid plains on the sea- coast, every climate is perceptible. The lakes are, Maracaybo in the north, 100 miles in diameter; Parima is 100 miles long, and 50 broad; lake Titicaca is in Peru ; and in Chili is the lake of the Tehuels. The rivers are those of the Amazons, or Maranon, the largest river in the world; Rio de la Plata; the Orinoco ; the Magdalena, running north to the Caribbean sea; St. Francis in Brazil, &c. The mountains are the Andes, 20,280 feet above the level of the sea, and 4,600 miles long. A chain proceeding from west to east, at nine or ten degrees north of the equator. The mountains of Parima, or the chain of the Cataracts of Orinoco, from 3° to 79 north latitude. The chain of Chiquitos, between 15° and 20° of south latitude. Between these three great ridges, three immense valleys open to the east, but shut to the west, extending from the Andes to the shores of the Orinoco, Amazons, and Buenos Ayres. Of these plains, that of Amazons is covered with impenetrable forests; while those of Orinoco, and Pampas, or Buenos Ayres, are grassy valleys or Savannas, so level, that for 800 square leagues, no elevation or inequality can be seen. North America.-The United States of America occupy that portion of North America which lies between the Missis- sippi on the west, the lakes and the St. Lawrence on the north, and the Atlantic and the Gulf of Florida wash their eastern and southern extremities. The population is above 12 mil- lions, including 1,200,000 slaves | And it is inferred, that the population of this country doubles itself every twenty years. • States. Relative Situations. Towns. Main . . . . . . . . . . . . . ... " | Portland. New Hampshire . . . . . . Portsmouth. Vermont, west of New e Hampshire ... . . . . ; Bennington. Massachusetts. . . . . . . . . . N Boston. Rhode Island... . . . . . . * | Newport. Connecticut. . . . . . . . . . Newhaven. New York. . . . . . . . . . . . New York, Hudson's River. New Jersey... . . . . . . . > to Trenton, on the river Delaware Pº }. * º | Philadelphia, on Delaware. Delaware . . . . . . . . . . . . Dover, on Delaware Bay. Maryland . . . . . . . . . . . . S.W. Annapolis, or Chesapeak Bay. Territory of Columbia. . . " " ' | WASHINGTON, on riv. Potomac Virginia ....... . . . . . . . Richmond, on James's River. North Carolina ........ Newbern, Nase River. South Carolina..'..... Charleston. Georgia. ... . . . . . . . . . . . Savannah,on SavannahSound -” Back Settlements. Indiana. . . . . . . . . . . . . . | N. to Clarksburg. Franklinia. . . . . . . . . . . . . } S. W. Knoxville, on river Tennessee. Western Territory . . . . N. Clarksville, on the river Ohio. Kentucky. . . . . . . . . . . . Lexington. Tennessee . . . . . . . . . . . . Nashville,on Cumberland Riv. The Aborigines (wild and rude tribes of savages) occupy all the part between Georgia and the river Mississippi.-The government is vested in a president, chosen every four years, and two councils or senates; the members of the Superior senate being chosen every sixth year, and those of the inferior every second year. The president is a democratical king, in whom the executive government is vested. Each province has its government or senate, consisting of a house of representa- tives. The president commands both the army and the navy ; the former is inconsiderable, but the latter augments with suspicious rapidity. The revenue is about twelve millions of dollars, the expenditure about ten millions; the national debt is seventeen millions sterling. The Americans are cold and reserved, evincing a contempt of strangers, and excessively | Green River, the Cumberland, and the Tennessee. bigoted in religious matters, though their tenets: are as various as schismatică invention can render Christianity. The col- leges and academies are numerous, but the American booksel- lers reprint twenty British works for one originally transatlan- . tic. The chief cities are, New York, Philadelphia, Charleston, and Baltimore, for commerce; and Boston for its fanatical spirit. New Orleans is situated on the Mississippi; Norfolk is the chief port of Virginia. The inland navigation of the United States is very superior, but the public roads are indifferent. The manufactures are in general in their infancy, though in some things the Americans have made considerable progress, as must be evident from the population being chiefly composed of Britons and Germans, the two most persevering mechanical nations of Europe. The climate is remarkable for sudden transitions from heat to cold; but the seasons in general cor- respond with those in Europe; and the soil is for the most part fertile. Three parts in four of the population are directly or indirectly connected with agriculture, which therefore thrives well; and while the southern states resemble our West India plantations, the orchards and corn-fields in the northern states bear a great resemblance to those of Lothian and Worcester- shire. The rivers are, the Mississippi, the Ohio, the Illinois, the Uisconsin, the Chipaway, St. Croix, the Great and Little Miami, the Wabash, the Great Kennaway, Kentucky, the Into the Atlantic flew St. Croix, Penobscot, the Kennebec, the Saco, the Merimac, the Connecticut, the Hudson river, the Delaware, the Susquehanna, the Potomak, James’s river, the Shenandoa, the Black Water and Staunton, the Pedee, the Santee, the Savannah, and the Attamala. The lakes, Cedar, Little Win- nepeg, and Leech, Champlain, Lake George, Oneida, Cayuga, and Sennaka. The others we have mentioned. The chief mountains are, the Apalachian, the White and Green mountains in the northern districts, the Land’s Heights, the Savage and Bald mountains, and the Allegany or Blue mountains. The aboriginal forests are large and numerous; and the lake of the Dismal Swamp, 150,000 acres in extent, is covered with trees of prodigious height, choked up with brushwood, so as to render the swamp impervious. Bears, wolves, deer, and other wild animals, roam undisturbed here. The lake or marsh of Ona- quafenoga, in Georgia, is 300 miles in circumference, and con tains many fertile islands, one of which, called Paradise, or the Happy Isle, is inhabited by a peculiar race of Indians, whose women, from their incomparable beauty, are called the daugh- ters of the sun. The islands belonging to the United States, are Long Island, a few insular strips of land near the shores of North Carolina, with others scattered along the coast, and in the various bays and lakes. ‘. The Spanish Dominions in North America.—These domi- nions are 2200 miles in length, and about 460 in breadth ; and the population amounts to eight millions, of whom four millions and a half are Indians, two millions and a half a mixed race, and one million of Spaniards. And we might divide them into East and West Florida, California, and New and Old Mexico: thus, 1st. On the Pacific are, Divisions. Rel. Sit. Chief Towns. California, n. w. . . . . © tº tº e º a º St. Juan. Sonora. . . . . . . . . . . . ~ Mazatlan. Guadalaxara ... . . . . tº Guadalaxara, on Rio Grande. Valladolid . . . . . . . . . Valladolid. Mexico ... . . . . ... . . . N. | Mexico, on the lake of Mexico. Puebla . . . . . . . . tº º 'º e | Tlascalla. Oaxaca ... . . . . . . . . . ;- to Oaxaca, on Rio Verde. Guatimala . . . . . . . . . | Guatimala. Nicaragua... . . . . . . . S. E. Fort St. Juan, on Rio de St. Juan. Costarico ... . . . . . . . Cartago. • Veragua. . . . . . . . . . . St. Yago. Panama . . . . . . . . . . . –0 | Panama, on Panama bay. x 2dly. On the Atlantic are, New Leon . . . . . . . . . New Santander. Vera Cruz . . . . . . . . . . Tampico, on Rio Tampico. Tabasco . . . . . . . . . . . N. Villa Hermosa, on Rio Tabasco. Yucatan: . . . . . . . . . . × 12, Salamanca. Verapaz . . . . . . . . . . . S.E. Santa Cruz, on the gulf of Dulce. Honduras . . . . . . . . . . Truxillo. º º º * - - - - - - - - - . - *º olº º º º º º, **º: ſº º º * º, - Pººle ºº: º: §º . º - Guayaquiº º º º - * º º º nº º º º y * - º - -º-º: º - - -__ --- º - - - º, ºr ºn ºlºr - ------ - º - - º º - ºurth-nº ºniºma º º º: Bo º º º- -- sourg Awis º: - *Tºº. ----- *George ºniº ſº --- --- - Bºi.… RICA. Tºto A M E A M E Diction ARY OF MECHANICAL scIENCE. 33 - 3dly. In the Interior are, New Mexico, proper Santa Fé, on Rio Bravo. Durango. . . . . . . . . . . Nombre de Dios. Zacatecas . . . . . . . . . . ( to S. Zacatecas. Guanaxuato . . . . . . . Guanaxuato. The soil, produce, and climate of these dominions are thus described : — Extensive savannas feed numerous herds of cattle ; the mountains abound in the precious metals; the climate is singularly diversified between the tropical seasons and rains, and the temperature of the southern, and even mid- dle countries of Europe. The climate has a ruling influence over the diseases of these regions, among which, the yellow- fever is one of the most fatal, but it usually confines itself to sea-ports. The soil is often a deep clay, surprisingly fertile, and requiring no manure, save irrigation; but the division of land is far more unequal than in Europe, yet agriculture flourishes. The chief products are wheat, cotton, indigo, tobacco, cochineal. California is famous for fish, and a pearl fishery; and in the centre of this peninsula is a plain of rock salt, as firm and pellucid as crystal.—The province of Vallado- lid, the most delightful of these fertile regions, produces the pine-apple, pomegranate, fig, citron, lemon, orange, and cocoa- nut trees, sugar canes, indigo, jalap, &c. And its chief ports are Vera Cruz and Acapulco.—The kingdom of Mexico is by far the most important of these settlements, as its capital, Mexico, is the chief city of Spanish America. The population of this city is 150,000 inhabitants, and it is the seat of a vast commerce between Vera Cruz and Acapulco. Mexico is situated in a vast plain, 7475 feet above the level of the sea. The religion is the Roman Catholic, and one-fifth of the Spa- niards are ecclesiastics, monks, friars, and nuns. The inquisi- tion ruled here with fanatic ſury in former times. In Mexico there is an enclosure between four walls, filled with ovens, into which are thrown the unhappy victims of the inquisition, con- demned to be burned alive | There are in Mexico no remains of what our historians have fabled, and its chief remaining antiquities appear to be earthenware, ruins of dykes and aque- ducts, some colossal statues, hieroglyphical pictures, weapons, and knives of sacrifice. The government of Mexico is the chief of Spanish America, and it is extended over a territory equal to an European empire. The sovereign's power extends to the patronage of all the churches, the disposal of lucrative offices, monopolies, connivances, presents; and his court, upon a regal plan, is hemmed in by horse and foot guards, while his household and numerous attendants swell the pageantry. Guatimala is ruled by a president, who is also captain-general of the troops. Each of the interior provinces has its president. The army has been computed at 40,000 men; but it is difficult to speak near truth on the revenue, and several other matters of general geography, belonging to the Spanish dominions in North America. The independence of Mexico has been formally acknowledged by Great Britain. This country is still partly ruled as formerly, but it seems proba- ble that its government will be assimilated to that of the United States. The chief towns are, Tasco, Guanaxuato, Guatimala, Xalappa, Merida, Santa Fé, Panama, Porto Bello, and Aca- pulco. Tasco, situated 6000 feet above the level of the sea, is the seat of the noted mines of Moran and Oyamel. The sur- rounding region is covered with oaks and pines, and the crops of wheat and barley are very abundant. But Guanaxuato boasts the richest silver mines in the world; that of Valencia yielding its proprietor a revenue of £130,000 annually, and produces above half a million sterling. This mine is 280 fathoms in depth. In 1773, Guatimala was destroyed by an earthquake, and 8000 families perished; but the new city is well peopled. Xalappa is romantically situated in a fine climate, about the middle of Vera Cruz; and near it the snowy peak of Orizala, or the star mountain, rises to the sublime height of 17,390 feet above the level of the sea. In Merida, the capital, resides the governor of the province of Yucatan. Another governor resides at Santa Fé. Panama has a rich pearl fishery, and is the noted resort of merchant vessels. Porto Belio is a fine harbour, and is celebrated for its fairs, which are much frequented by merchants. And though the clinate of Acapulco be sultry, it engrosses the chief Indian trade over the Pacific. - The British Possessions: Canada, &c.—Canada extends. from the Gulf of St. Lawrence to Lake Winnapeg, 1400 miles; and its average breadth is about 200 miles. This country is in general mountainous and woody ; but in Upper Canada there are Savannas and plains of great beauty. In the lower pro- vince, the soil is a loose, black, fertile mould, of a foot thick, resting on clay. The climate is salubrious, but cold during winter, which continues eight months severe. Canada exports furs, hides, timber, fish, potash; and receives spirits, wine, tobacco, sugar, salt, and manufactured goods, chiefly from England. The established religion is the Protestant, super- intended by the Bishop of Quebec. But as the French were the first possessors of Canada, there are many Catholics. The Protestant clergymen are 12, the Catholic 125, from which it appears in what ratio the Catholics outnumber the Protestants. The chief towns are, Quebec, Sorelle, Trois-Riviers, Montreal, and Kingston. Quebec, upon the north of the river St. Law- rence, is immortalized by the death of General Wolfe. The population amounts to 10,000 souls; and the adjacent country presents much sublime and picturesque scenery. From December to April. the river is frozen over here. Montreal, 150 miles above Quebec, has about 7000 inhabitants, and its chief traffic is in furs, which the traders purchase from the Indians. Kingston is situated on the Lake Ontario, at the grand egress of the river St. Lawrence. Trois-Riviers is the grand resort of the Indians, and its population is not more than 1500 souls.-The island of Newfoundland, about 320 miles in length and breadth, has, as its chief towns, St. John, Placen- tia, and Bonavista. The population does not exceed a thousand families during the winter. The celebrated station on the banks of Newfoundland is more than 400 miles in length, and about 140 in breadth; the water being from twenty-two to fifty fathoms, with a great swell, and frequently a thick fog. The chief fishery begins on the 10th of May, and continues till the end of September; the greatest number of cod-fish taken by a single fisherman is about twelve thousand, the average is seven thousand. The largest fish are each about four feet three inches in length, and weigh about forty-six pounds. Upwards of 500 English vessels frequent these banks, and about the same number of Americans and French.-New Brunswick is sepa- rated from the province of Main, belonging to the United States, by the river St. Croix; and the Apalachian mountains pass along the north-west of this province. The capital is Frederick Town, on the river St. John, which affords a com- mon and near route to Quebec. Some settlements, commanded by Fort Howe, have been established in the bay of Fundi.— Nova-Scotia is a province on the east of Canada, and south of the river St. Lawrence. New Brunswick is the more northerly, Nova Scotia the more southerly. And the Bay of Fundi, between New Brunswick and Nova Scotia, extends fifty leagues inland, the ebbing and the flowing of the tide being from forty-five to sixty feet. Halifax, the capital of Nova Scotia, contains 15,000 inhabitants; and the Bay of Fundi is remarkable for its sublime and picturesque scenery. The island of Cape Breton, close to Nova Scotia, has a cold and foggy climate, and the soil is a mere moss, unfit for agriculture. But the fur trade and fisheries, at its chief towns, Sidney and Louisbourg, are very considerable. The Bermudas, or Summer Islands, are situated about half-way between Nova Scotia and the West Indies. Native Tribes, and Unconquered Countries.—These are, Greenland, Labrador, the regions round Hudson’s and Baffin's Bays; the central parts, and the western coast. Greenland was visited by the Norwegians in the year 982, above 500 years before Colon discovered San-Salvador or Cat Island. But about 1406, about eighty-six years before Colon's discovery, by the gradual increase of the arctic ice, the Norwegian colony was completely imprisoned by the frozen ocean. This dreary region consists of rocks, ice, and snow ; and in the south-west there are Danish and Moravian settlements. The botany is made up of junipers, willows, and dwarf birches. The zoology, of rein-deer, wolf-dogs, foxes, bears; sea-fowl, fish, and a few species of insects. The natives are American Samoieds, or Iskimois, short of stature, with long black hair, small eyes, and flat faces; and their numbers do not exceed ten thousand, chiefly employed in catching seals and in fishing.—Labrador, K 34 A M E A M E DICTIONARY OF MECHANICAL SCIENCE. supposed to have been discovered by the Norwegians about the year 1003, receives its name from a Portuguese navigator, who, in 1500, arrived at it in search of a north-west passage. The natives are Iskimois savages of filthy manners, and a race of mountaineers resembling gipsies, but with French features, and in their religion Roman Catholics. This country abounds in bears, rein-deer, foxes, martins, and beavers; the lakes, rivers, and pools, are rich in salmon, trout, pike, barbel, and other fishes. The bears are remarkably fond of salmon, and will assemble in numbers at the cataracts where the salmon ascend, to catch their favourite prey. Some dive after the fish, and do not appear again till at the distance of sixty or seventy yards. But they are usually successful in the pursuit. Others appear mere loungers, that have come only to see the sport, and enjoy the promenade among the surrounding alders, spruce-firs, larches, birch, and aspin-trees. Nor is it an unusual thing for two score of white bears to be present at this specta- cle !—The regions round Hudson's Bay are held by the Hud- son's Bay Company, and the North-West Company, both Eng- lish ; hence these regions have been called New Britain. The parts on the west of Hudson's Bay have also been called New North and South Wales, while that on the east, between Labrador and the bay, is called East-Main. Hudson's sea pre- sents bold rocky shores, or marshes, and large beaches; the winters, even in latitude 75°, are extremely severe; mock suns or halos are frequent; the sun itself rises and sets with a large come of orange-coloured light; the aurora-borealis dif- fuses its variegated splendour with as much brightness as the full and cloudless silvery moon; and the stars scintillate with uncommon redness. The central parts are only known, from the travels of Hearne, Mackenzie, and Franklin. These parts are inhabited by various tribes of Indians, who are chiefly em- ployed in hunting and fishing. The animals found are those peculiar to northern latitudes; the rivers and lakes are stored with fish and water fowl ; and so numerous were the herds of elks and buffaloes which Mackenzie met with, where the scenery was interspersed with hill and lawn, that the country resembled a stall-yard. The natives towards the Pacific are fairer than those of the central parts, and evince a decided superiority in the arts and in their manners. The western coast comprises all those shores stretching from Behring's Strait to New Mexico. It is bounded inland by a great chain of mountains, and the whole region is chiefly alpine, bearing a strong resemblance to Norway. The natives are savages; in some tribes mild and aſſable, as well as just in their dealings; in others, cruel to strangers, and brutal to their captives taken in war, as the savages of Nootka and the Mosquinas, who massacred the Franciscan missionaries; and, among the whole, the females are held in abject subordination. The Isles of Colon, or the West Indies.—These islands are Cuba, St. Domingo or Hayti, Jamaica, Porto Rico, the Antil- les, Caribbee or Leeward islands, Trinidad, and the Bahama islands.-Cuba is 700 miles long, but only 70 broad. This island is fertile, producing excellent sugar, and the famous Havannah tobacco. It is governed by a Spanish governor- general and eighteen magistrates. The chief town is Havan- nah, and the people are fond of bull-fights, cock-fightings, balls, and good living.—St. Domingo, or Hayti, is now an inde- pendent empire; the national assembly of France having passed decrees for the mulattoes, or people of colour, to vote for representatives, the slaves rose against their oppressors, and after many battles, have effected their independence ; and the island is now governed as a republic, after the fashion of the United States of America. The products of this island are similar to Cuba and Jamaica.—Jamaica, an English settlement, is 170 miles long, and 60 broad. It is divided into three coun- ties, Cornwall in the west, Middlesex in the centre, and Surrey in the east. St. Jago or Spanish town, is the capital, and Kingston the chief sea-port. The products are sugar, rum, coffee, indigo, ginger, pimento. The legislature consists of a captain-general, or governor; a council of twelve, nominated by the king ; a house of assembly, of forty members, who are freeholders. The bread-fruit tree has been introduced. The Blue Mountains rise 7430 feet above the level of the sea.— Porto Rico, belonging to Spain, is 120 miles long and 40 broad. It is a fertile, beautiful, and well-watered island; producing Dutch. cotton, sugar, ginger, hides, drugs, and sweetmeats.--The Caribbee Islands, extending from Tobago in the south, to the Virgin Islands in the north, are of noted fertility and commer- cial advantage, producing sugar, cotton, rum, coffee, indigo, &c. These islands are, Barbadoes, Antigua, St. Christopher’s, St. Vincent, Dominica, Grenada, Montserrat, Nevis, Trinidad, and the Virgin isles, belonging to Great Britain. The French Caribbee islands are Martinique, Guadaloupe, St. Lucie, Tobago, and some islets. The Danes possess St. Croix, St. Thomas, and St. John, attached locally to the Virgin group. St. Bartholomew belongs to Sweden; and St. Eustatius to the Trinidad is about sixty miles long by fifty broad; the climate is delightful; and two-thirds of the soil is most fertile. —The Bahama or Lucayos Islands comprise Abaco, Bahama Eleuthera, Providence, Cat Island or San-Salvador, Crooked Island, and Cayo. The inhabitants are whites, English and Spanish, with many negroes. These West India islands afford cotton, logwood, mahogany, the cabbage-palm-tree, rising 200 feet, the tamarind tree, with its airy elegance and acid pods, the alder, and elm ; the fruits are apples, peaches, figs, grapes, pomegranates, oranges, pine-apples, cashew-nuts, cocoa-nuts, and guavas; and the spices are numerous and exquisite. South America.-The extent of this continent has already been noticed. It is divided into the Spanish dominions; the Portuguese dominions; the French dominions; the Dutch ter- ritories; and the countries possessed by the native tribes. The Spanish dominions once comprised the viceroyalties of La Plata, Peru, and New-Granada, with the Caraccas, and some inferior governments. The Portuguese dominions are, Brazil, and part of Guiana ; the French and Dutch were also in Gui- ana; and the native tribes possess Patagonia and other coun- tries. The Spanish dominions, that is to say, the countries subject to Spaniards, whether independent, or governed by the mother country, contain a population of 43 millions of souls; and are divided into, 1st. The Territories on the Caribbean Sea, comprising Venezuela, Cumana, Guiana: chief towns, Leon de Caraccas, Cumana, St. Thomas. 2dly. The Territo- ries on the Pacific, comprising New Granada, Peru, Chili, La Plata : chief towns, Carthagena, Lima, St. Jago, Buenos Ayres. Venezuela is now an independent republic; a portion of Cumana is also free from the Spanish yoke; and the whole of these territories have, in our own times, been erected into independent states. (1825.) º The Kingdom of La Plata.-The kingdom of La Plata, or Buenos Ayres, may be thus described. In extent it reaches from 14° south to near 38°, that is, 24°, or 1440 geographical miles in length ; and in breadth about 12°, or 720 geographical miles. The population is about 2% millions of souls. The government was managed by a viceroy, who had also the title of captain-general, and his jurisdiction extended to the whole of the political management, except the royal treasury; which was managed by the paymaster-general of the army. The strength of the army is not considerable, but some of its native troops are expert in the spear, the rope, and the ball. In their manners, the people resemble the European Spaniards, because it has been the policy of Spain to excite the colonists to remain in the new territories; and this she did by the superlative prudence of the council of the Indies, an assembly of her most enlightened men. Indeed, the whole government of the Spanish colonies in America, has, for a series of years, been managed by this council. The chief cities are, Buenos Ayres, on the west side of the river La Plata, an agreeable place, containing 40,000 inhabitants, and may be considered the grand mart of European goods passing to Peru. Montevideo is celebrated for its harbour; Santa Fé is on the great river La Plata; Potosi is famous for its mountain of silver, which the avarice. and labours of 270 years have scarcely lessened. La Paz, an elegant and clean town in the same region, trades chiefly in the noted tea of Paraguay. Mendoza, in a pleasant situation on the eastern declivity of the Andes, is in the celebrated passage through those mountains to Peru. Chucuito, on the grand Lake Titicaca, is a cheerful and convenient town, surrounded by a cold climate, but a fertile soil., Pimo is a rich and popu- lous town; Oruro is noted for its mines; Oropesa is the capital of Cochambamba, once the granary of Peru; Santa Cruz is a famous missionary station; Jujuy is celebrated for its cattle- A M E A M E 35 DICTIONARY OF MECHANICAL SCIENCE. trade ; Salta for its annual fair in the valley of Lerma, where 60,000 mules and 6000 horses are commonly collected for sale. The commerce between Buenos Ayres and Peru is carried on by means of little waggons drawn by oxen as far as Jujuy and . Mendoza, where it is necessary to have recourse to mules on account of the mountain. Commerce having increased the circulation of money, agriculture has made rapid progress amidst the fertile plains of this extensive region. In regard to its natural geography, the kingdom of La Plata boasts of noble rivers, as the Parana or La Plata, the Paraguay, the Uruguay, and the Mendoza. The Mendoza has pierced a hill, and formed a natural bridge, over which three waggons may pass abreast. And its lakes are generally salt; but some are sweet water, and that of Titicaca is celebrated for an island in which the Incas dedicated a temple to the sun. The Indians have a tradition, that when the Spaniards entered the country, great treasures were thrown into this lake, and among others the great chain of gold, so long that 6000 men danced in the ring it formed. The mountains of Cordova, by some regarded as a branch of the Andes, are covered with perpetual snow. In the botany of La Plata, we find the cinchona, or Jesuits’ bark, rhu- barb, jalap; the carrob tree, which in winter affords a palatable drink and food to both man and beast; the tea of Paraguay, com- posed of the leaves of a small tree resembling the orange. In the zoology of this country, we find the American camel, or native sheep, from the wool of which a most elegant and durable cloth is manufactured; the American tiger orjaguar, and the puma or lion; the wild cat, the elk, the ant-bear, a kind of deer, hippo- potami; the condor, an immense bird with a red crest, and black body spotted with white ; the Paraguayan ostrich, par- tridges, serpents of prodigious size, &c. The mineralogy of this kingdom is extensive, and lucrative beyond all belief; for not to speak of Potosi, the mines of gold and silver are immu- mcrable. In the province of Chaco, a mass of native iron, per- ſectly malleable, has been found. Near Jujuy is the hall of Eolus, a singular volcano, whence the winds rush out with overbearing whirls and clouds of dust. Not far from Cordova pent up winds issue out with violence by small apertures from the rocks, and produce a noise resembling the discharge of artillery at the siege of a fortress. And in the town itself, during a still night, the inhabitants hear passing, as it were from street to street, a dull murmur, like the noise produced by thumping with a wooden pestle in a huge mortar. Kingdom of Peru.—Peru borders on New Granada on the north; on the north-east it joins the Pampa del Sacramento; on the east, the savage nations of the Pajonal ; and on the south-east, the kingdom of Buenos Ayres. Its length has been computed 423 geographical leagues, and its breadth 80 leagues. The provinces are forty-two, but only a few have been described, though, among the native nations of America, the Peruvians are by far the most interesting. The number of towns and villages exceeds 1500. Like the other governments of Spanish South America, the viceroyalty of Peru consisted of two branches, political and ecclesiastical. The archbishop of Lima has four suffragans, and besides the chapters of these bishops, there are 557 curates of the royal presentation. In the Peruvian valleys between 5° and 15°, no rain falls, but vege- tation is supported throughout this region by liberal dews. The high table-lands of the Andes, at the height of 10,000 feet above the level of the sea, enjoy a perpetual spring united with an etermal autumn; the fields are always verdant, the grains ever wave in golden harvests; and the fruit-trees are in blossom, in ripening, or in matured fruit. The chief cities are, Lima the capital, containing a population of 52,000 souls, and carry- ing on a great commerce with all parts of the world, by means of intermediate agencies: Cuzco, the second city, once the seat of the Peruvian monarchy, and having a population of 26,000 inhabitants. Lima is the maritime, Cuzco the inland, capital. The other cities are, Arequipa, Guamanga, Truxillo, Arica, Oropesa, Jauja, Lambayeque, Caxamarca, Ica, and Guanuco. Truxillo is subject to earthquakes; for unluckily the earthly paradise of the Andean table-land is in many places but an insidious soil, encrusting subterranean fires of sulphureous, alkaline, and aqueous matters, in perpetual fusion, to pour forth tremendous showers of destructive lava. The botany of Peru and Chili is extensive and various, for while the valleys on the sea-shore boast the common tropical plants, the milder plains on the Andean table-land are favourable to plants of a hardier constitution. The zoology of Peru differs little from that of La Plata; the mountain cat, a species of deer, foxes, bears, wolves; a sea-fowl with feathered body and mem- branous wings like the bats. The flamingo frequents the lakes. The silk-weaving spider, as large as a crab, and with teeth like a rat's, abounds in Jaen. In short, the whole country of Peru is one vast field of natural curiosities. - The Kingdom of New Granada.—New Granada extends from 34° south latitude, to 12° north latitude, or 1549, being 930 geo- graphical miles: and the medial breadth has been assumed at 240 geographical miles. The provinces are twenty-four in al]. and the following is their natural geography:—The province of Jaen de Bracumoras, the most southern, producing gold, cot– ton, chocolate, and tobacco. The district of Cuenca, situated on the table-land of Quito, is of benign temperature, produ- cing abundance of cattle, sugar, cotton, and grain. Macas, a considerable province on the eastern declivity of the Andes, has a warm and moist climate, and produces cotton, sugar, tobacco, and cinnamon. Riobamba, noted for the earthquake of 1797, when only 400 persons escaped out of 9000 ! Guaya- quil is celebrated for its commerce. Terra Firma is a name given to Panama; and the province of Darien is extended on both sides of the gulf so called. Santa Fé enjoys a perpetual Spring, and the abundance of nature may be presumed, from the fact, that here there are two harvests. San Juan de los Llanos consists of prodigious plains, of a fertile soil, and con- taining an abundance of cattle, with some gold mines. Antio- quia is chiefly celebrated for its gold mines. Quito enjoys an uniform temperature ; and the capital of the same name is famous as being the place where the French mathematicians measured a degree of the meridian. Popayan enjoys a per- petual spring, and abounds in fruits. The people of this pro- Vince are noted for their integrity. Carthagena is noted for its European fashions, imported since its increasing commerce, wealth, and luxury. Santa Marta is famed as the province in which the Andes terminate. The chief rivers are the Magda- lena and the Cauca. Some of the most useful vegetable pro- ductions have been already mentioned, as belonging to the other kingdoms; but there are plants peculiar to the Andes, whose genera, species, and nomenclature, belong not to this work. In the zoology, we find the tapir, an animal resembling a cow, but about the size of an ass; wild boars, deer, ant- eaters, the jaguar, the puma, wild cats, serpents, and alliga- tors. In the mineralogy of New Granada, we find the rich gold mines of Choco and Antioquia; the silver mines of Mar- quetones; the emerald mines of Muzo; and the copper mines of Velez. Among the natural curiosities may be mentioned the vertical cataract of Bogota, precipitating its waters from a height of 300 fathoms. This cataract is the river Feunza, which, after passing along a narrow channel on a high table- land, is poured as from the spout of a vase in one arch of 1320 feet. The noise from the fall in the basin below, the spray, the clouds of vapour, the rainbows, the surrounding pictu- resque scenery of trees and shrubs, render the cataract of Tequendama one of the wonders of the world ! The Government of the Caraccas.-This government includes Venezuela, Maracaibo, Varinas, Cumana, (including Barce- lona,) Spanish Guiana, and the Isle of Margarita. This govern- ment is now considered the republic of Venezuela, and there- fore we shall notice the rather, its products, commerce, cities, and natural geography. Singular as it may appear, there are rivers in this district which rise on the sea-coast as it were, and flow inward. Becves, horses, and mules, pasture in the interior; the vales alone are fertile. The cultivated articles are chocolate, indigo, and tobacco; but Hayti used to yield ten times the produce of the Caraccas. The great ports are Guayra and Porto Cavello, but the commerce is inconsiderable, and for a long time the greatest contraband trade was carried on. The chief towns are, Caraccas the capital, which, though cnjoy- ing a perpetual spring, was lately injured by an earthquake. Porto Cavello, an unhealthy place, and dangerous of access to the crews of foreign vessels. Valencia, a meat town; Maracay, a beautiful village, in the rich vale of Aragon; Tulmero, in the same vale, a handsome town; Victoria, Coro, Cararo, Barqui- 36 A M E A M E DICTIONARY OF MECHANICAL SCIENCE. simeto, Tocuyo, Guanana, Calabosa, Pao, San-Philippi, and Nirgua, are all places of minor importance. Cumama used to form a delegated government, consisting of the two provinces of Cumana and Barcelona, Cumanais subject to frequent earth- quakes. Barcelona is noted chiefly for its breeding of swine; and the isle of Margarita as a military station, for the invasion of the Caraccas. The town of Maracaibo is rather unhealthy, apd the thunder storms are terrible, but without them earth- quakes prevail. The tobacco of Varinas is highly celebrated. The lakes are Maracaibo, famous for its mineral pitch, which at night serves, by its bituminous ignited vapours, as a lantern or pharos to the Spaniards and Indians; and the lake of Valen- cia, which, though receiving twenty rivers, discharges its superfluous waters by a subterraneous tunnel of evacuation, and nourishes amidst its swampy waters monstrous lizards, on which the natives feed. The rivers are, Orinoco, Aphuro, the Portuguesa, the Guarico, the Unari, and the Guarapicha. In the interior of Cumana there is a cavern called Guacharo, famous annong the Indians for being of immense extent, and serving as a habitation for thousands of a kind of nocturnal birds, (or goai-sucker,) which the Indians suppose to be the souls of their ancestors. This remarkable cavern is therefore visited with great ceremony. Spanish Guiana. –Spanish Guiana is the province which, in some maps, the geographers call New Cumana, or New Anda- lusia. The territory of Guiana is bounded by the Orinoco, and the Negro rivers in the west and north ; on the south by the Maranon; on the east by the Atlantic ocean. The part of Brazil on the north of the river Maranon, is called Portuguese Guiana. Spanish Guiana is bounded on the south-east by Dutch and French possessions; on the south, by the Portu- guese; on the west, by the Rio Blancho, or rather the great river Negro; and the Orinoco on the south. Guiana is the seat of a bishop : the inhabitants sleep on the terraces of their houses during the great heats. The Kingdom of Chili.—Chili is a delightful country, extend- ing for more than 1260 geographical miles, along the great Pacific Ocean, flanked and protected by the vast belt of the Andes, which sends forth copious rivers to irrigate this envied soil. The breadth is about 210 miles. The northern boundary is the desert of Atacama; the Andes on the east divide Chili from Cayo, in the viceroyalty of La Plata; on the south it is bounded by barren mountains; and the Pacific Ocean washes its western shores. The grand belt of the Andes is here 120 miles broad, with transverse ridges full of ruptures and preci- pices; and eight or nine paths open to the Andes on the east, like those over the Alps in Switzerland, on shelves in the per- pendicular rocks, hanging over profound precipices, so dan- gerous and difficult, that the steadiest mule ceases to be useful in those situations. The four seasons, in an inverted order, are as regular in Chili as in Europe. The fertility of the soil may be inferred from the fact, that a great part of it was in constant labour long before the Spaniards visited Chili, and to this day manure is unnecessary, for it yields, in general, from sixty to seventy-fold ! and, what is singular, in a country wherein the soil, after a lapse of ages, and the avarice of man, has so little degenerated. Chili is the seat of the richest metal- lic ores; lead is found, of excellent quality; iron abounds, but it is neglected; the copper is perhaps superior to the British. The provinces of Santiago, Aconcagua, Coquimbo, and Copi- apo, are celebrated for their silver mines; nor is there a moun- tain or hill which yields mot gold, the purest in the world. With such a fertile soil, and enjoying so delightful a climate, the botany of Chili partakes of the plants of both hemispheres. Nettles, as in Europe, also our potherbs and fruits; and the sugar cane and sweet potato, and other tropical plants, flourish in the northern parts of this fine country. Our fine white strawberry, tipped with purple, and three inches in cir- cumference, is derived from Chili, where it is cultivated as a crop; wild tobacco, sudorific and febrifuge plants; incense, equal to that of Arabia; balsam, excellent, both as an odour and a curative medicine. In the zoology, reptiles are rare; the seas abound"in fish, the shores in lobsters and crabs, with oys- ters, seals, sea-cows, and innumerable aquatic fowls; and the hills in bees. The ſlamingo decorates the rivers, the hum- ming bird the groves of flowers. The ostrich in Chili is equal to that of Africa; vultures and eagles, and condors, haunt the frightful precipices of the Andes. And amongst the quadru- peds we find dogs, hippopotami, foxes, lions of America; a singular wild horse, with cloven feet; and most of the Euro- pean animals have improved in Chili. The most singular phe- nomenon, connected with the natural history of Chili, is the fact, that the ocean is retiring very rapidly on this coast, leav- ing curious grottos, hung with shells; and, in two instances, detached masses of white marble, scooped out like churches. The aboriginal Chilese are the Arancans and the Puelches. The former are the genuine representatives of the ancient Chilese ; the latter, more rude and savage than the other natives, inhabit the mountains, and often change their abode, like the pastoral tribes of Asia. The Arancans have little beard; they are intrepid in war, hardy to endure fatigue, faith- ful to promises; but addicted to some of the savage vices. The Puelches are bold in war, faithful as allies, and may still be considered the unconquered Chilese. Such is the natural geo- graphy: the political is very brief.-Spanish Chili is divided into thirteen provinces, Copiapo, Coquimbo, Quillota, Acon- cagua, Melipilla, Santiago, Rancagua, Colchagua, Manli, Itata, Chillau, Puciancy, and Huilduilema. They also possess Port Valdivia, in the country of the Cuchi, the Archipelago of Chili; and the island of Juan Fernandez. The entire government is managed by a captain-general ; each of the provinces is ruled by a prefect, or corregidor. There are two vast bishoprics, Santiago and Conception, both suffragans of the Archbishop of Lima. The inquisition prevails at Santiago. The population is singularly mixed; wealthis wasted on dress, and equipages and titles of Castile ; a countship being sold at so much, a marquisate at so much more, and the want of money alone . prevents the whole people from being a nation of dukes. Chili is the original seat of vaccination; and among its medicinal herbs the vira-vira expels the ague ; the payco assists indiges- tions: the culen supplies an excellent tea, known as a vermifuge; * palqui is esteemed a superior febrifuge to Peruvian aſk. - Brazil, and the Portuguese Possessions.—The Portuguesc possessions extend from the frontier of Dutch Guiana, in lati- tude 3° north, to Port St. Pedro, in latitude 32° south. These 35° of latitude give us 2100 geographical miles for one dimen- sion, and the other extent is even more, reckoning from Cape St. Roque to the settlement of St. Paul de Omaguas, on the river Amazons. The chief city of Brazil is San-Salvador, but Rio-Janeiro is more celebrated for its commerce; and the chief settlements are Para-Cano, on the estuary of the Mara- non; Pernambuco, Sergippe, Paraiba, Villa-Grande, &c. But the whole territory of Brazil is now divided into eight inde- pendent governments, besides that of Rio-Janeiro; and the whole is now under the immediate eye of the Emperor, of the family of the king of Portugal. The population is esti- mated at 250,000 whites; 600,000 negroes; and 1,050,000 of natives. The climate in the south is delicious, and the soil fertile; but the north is exposed to rains, thunder, and storms. The valleys are rich, the forests extensive, and the rivers and mountains are both numerous and grand. The productions are, Brazil-wood, ebony, and dye-woods; esculent plants, common to the tropical climes; raisins, cotton, coffee, rice, pepper, and fruits. The European settlers are gay, and fond of pleasure; their domestics and labourers are slaves; and the indigenes are irreclaimable savages, muscular and active. Rio-Janeiro has a capacious and excellent harbour, protected by the castle of Santa-Cruz; yet both here, and in the other towns, the ceremonies of religion have degenerated into a vul- gar worship of images. The mines of diamonds, in the pro- vince of Serro-de-Frio, and about latitude 17°, (and thus cor- responding with the celebrated diamond mines of Visapour, in Hindostan.) are very much famed, though the brilliants they produce are much inferior to those of the East, being of a brownish obscure hue, and not of so fine awater. But diamonds are baubles in comparison of the valuable herds of wild cattle which range the forests of Brazil, and the medicinal plants of high estimation, that grow spontaneously, and in abundance. The French Settlements in Guiana.—These settlements extend about 350 miles in length, by 240 in breadth; and the chief town is Cayano, whence the whole territory is called A M E A M P 37 DICTIONARY OF MECHANICAL SCIENCE. Cayenne. The soil and climate are good, the Cayenne pepper is well known; and the other products are, sugar, cocoa, vanilla, and indigo. The Dutch Possessions.—These are Dutch Guiana, called also Surinam, in length 350 miles along the coast of the Atlan- tic, by 160 in breadth inland. The chief towns are, Para- maribo, on the west bank of the Zealand river; and Demarara, on the river Esiquibo. It was this country that the unfor- tunate Raleigh attempted to penetrate, by the river Caroni, to the lake of Parima, whose sands were fabled of gold dust, and in the vicinity of which was the golden city of Manoa del Dorado. In the botany of Surinam we may notice its palms, of majestic height; the quassia; the castor-oil mut; ipeca- cuanha; caoutchouc, or Indian rubber: and poisonous trees and climbers abound. The entangled forests, and the Swamps, are the sure retreats of panthers, serpents, and abominable reptiles. º Native. Tribes and Unconquered Countries.—The internal nations are, the Abipons, a warlike tribe, and chiefly cavalry : the Mocobs; the Tobas ; and the Aucas, in the same quarter. Towards the southern parts are the Puelches, or Patagonians ; the Araucanos; the Telmels; and the Huilliches. The Abi- pons bury their dead under the shade of trees : and the horses of a chief are always sacrificed at his death. The Patagonians are the wandering, but humane Tartars of South America. And they bury their dead in a sitting posture, in square pits, with their weapons and cups beside them. These pits are annually opened by the matrons, and the bones of the skele- tons dressed, those of the slain horses around being supported by props. Or they transport their dead to the sea-shore, where they deposit them in tents, with the skeletons of their horses placed around. Islands belonging to South America.-These are the Gala- pagos; the isle of St. Felix; Juan Fernandez ; the archipela- goes of Guaytecas and Toledo; in the former is the isle of Chiloe, 140 miles long, and 30 broad; in the latter is the isle of St. Martin, with some Spanish factories. Terra-del-Fuego, a dreary region, inhospitable and cold; and the isle of Staten- land, is divided from Terra-del-Fuego by the straits of the Mairo. These countries, though in the reverse parallel of Pati- tude (that is to say, in 55#9 south latitude,) corresponding with Newcastle-upon-Tyne, in Northumberland, are yet more cold, and more severely frozen, than Lapland, in 70° of latitude North. The Falkland isles, (or Malouins, as the French call them,) boast of two, about 40 miles square, each ; but the abun- dance of fowl and fish, caught here, ill make up the deficiencies felt from the poverty of the soil, and the perpetual storms which vitiate the climate. . The isle of Georgia, to the south- east of the Falkland islands, though a land of ice, with vales destitute of trees and shrubs, and presenting only a coarse species of grass, is inhabited by the hardy lark, - Southern, or Antarctic Continent.—This important discovery, which will be attended with incalculable advantages to our trade in the South Seas, was made in 1819 by a Mr. Smith, master of the William, of Blythe, in Northumberland. South Sea traders, who, during hostilities between this country and Spain, have been subjected to the greatest difficulties and privations, will now be independent of Spain, or any other power possessing South America. Mr. Smith ran for 2 or 300 miles along this continent, which formed large bays, abounding with the spermaceti whale, seals, &c. The drafts and sound- ings taken by the discoverer, are in the possession of our government. The following is the brief account which has been given of this discovery :—“A Mr. Smith, master of the William, of Blythe, in Northumberland, and trading between the Rio Plata and Chili, in endeavouring to facilitate his pas- sage round Cape Horn, in 1819, ran to a higher latitude than. is usual in such voyages, and in latitude 62. 30. and 60. west longitude, discovered land. As circumstances would not admit of a close examination, he deferred it until his return to Buenos Ayres, when he made such further observations as convinced him of the importance of his discovery. On making it known at Buenos Ayres, speculation, was set on the alert; and the Americans at that place became very anxious to obtain every | information necessary to their availing themselves of a disco- very which they saw was pregnant with vast benefit to a com-. mercial people. Our i in the East and West Indies. plant, both as a spice and medicine, are well known. In culi- Captain Smith was, however, too much of an Englishman to assist their speculations, by affording them that knowledge of his secret which it was so necessary for them to possess, and was determined that his native country only should enjoy the honour and advantages of his discovery ; and on his second voyage to Valparaíso, he devoted as much time to the development of it as was consistent with his pri- mary object, a safe and successful voyage. He ran in a west- ward direction along the coasts, either of a continent or numer- ous islands, for 2 or 300 miles, forming large bays, and abound- with the spermaceti whale, seals, &c. He took numerous soundings and bearings, draughts and charts of the coast; and in short, did every thing that the most experienced navigator, despatched purposely, for the object of making a survey, could do. He even landed, and, in the usual manner, took possession of the country for his sovereign, and named his acquisition New South Shetland. The climate was temperate, the coast mountainous, apparently uninhabited, but not destitute of vegetation, as firs and pines were observable in many places; in short, the country had, upon the whole, the appearance of the coast of Norway. After having satisfied himself with every particular that time and circumstances permitted him to examine, he bore away to the north, and pursued his voyage. On his arrival at Valparaiso, he communicated his discovery to Captain Sherriff, of his Majesty’s ship Andromache, who hap- pened to be there. Captain Sherriff immediately felt the importance of the communication, and lost not a moment in making every arrangement for following it up ; he immediately despatched the William, with officers from the Andromache; and in this stage the last letter from Chili left the expedition, with the most sanguine expectation of success, and ultimate advantages resulting from it; and if we are correctly informed, a fully detailed narrative has been forwarded to government.” —Captain Cook penetrated to a much higher latitude, and drew his conclusion from observing nothing but vast moun- tains of ice ; yet his meridian was 45 degrees further to the west of New South Shetland, leaving a vast space unexplored on the parallel of 62, between that and Sandwich Land, in longi- tude 28 west. He again made 67, or thereabouts, but in longi- tude 137 to 147 west. Perouse ascended no higher than 60.30; Vancouver about 55.—The Russian antarctic expedition, under Captain Bellinghausen, has, in 1819 to 1824, discovered two new islands within the antarctic circle. Both islands lie in about 69° south latitude ; one of them, the isle of Alexander I. in 730 west longitude ; the other, Peter Island, in 19° west longitude. Both were closely enveloped in ide, and no examination could be made of them. AMETHYST, a transparent gem of a purple colour, found in the East and West Indies, and several parts of Europe. In Heraldry, the term signifies purple colour. AMIANTHUS, in Mineralogy, earth flax, a fibrous, flexible. elastic, mineral, found in Germany; and by Kirwan classed along with the muriatic genus of earths, because it contains about one-third part of magnesia. . - AMMI, Bishop's weed, the seeds of which are ranked among the four lesser hot seeds; but are scarcely otherwise made use of than as an ingredient in theriaca. - | AMMODYTES, the sand eels. | AMMON, the Egyptian Jupiter, worshipped under the figure of a ram. AMMONIA, a volatile alkali: , - AMMONIAC, a vegetable, gummy, resinous juice. SAL AMMONIAC, muriate of anjinonia, a native salt.” AMNIOS, a thin pellucid membrane that surrounds the foetus in the womb. - - - AMOMUM, ginger, which is cultivated like potatoes, both The uses of the root of this nary matters, ginger is one of the best substitutes for eggs, as in, making, common suet dumplings, and puddings of all kinds. , , AMORTIZATION, alienation of lands to a corporation and their successors. . . - AMPELITES, cannel coal, or candle coal. See CoAL. AMPHIBIOUS ANIMALs, include all: animals that live with equal facility on iand or in water, and some others which do L 3S A M U A N A DICTIONARY OF MECHANICAL SCIENCE. not exactly conform to this description. The amphibia, from the structure of their organs, and the power they possess of suspending respiration at pleasure, support uninjured, a change of element, and endure a very long abstinence. The lungs differ in appearance from those of other animals. Num- bers of amphibia possess a high degree of productive power, and will be furnished with new feet, tails, &c. when, by any accident, those parts have been destroyed. Their bodies are sometimes defended by a hard, horny shield or covering; some- times by a coriaceous or leathery integument; sometimes by scales; sometimes they have no particular coating. The am- phibia, in general, are tenacious of life, and continue to move and exert many of the animal functions, when deprived of the head itself. By far the greater part are oviparous, some exclud- ing eggs, covered with a hard or calcareous shell, like those of birds; others, such as are covered only with a tough skin, resembling parchment; and in many, they are perfectly gela- tinous, without any kind of external covering, as in the spawn of a frog. The amphibia are divided into RepTILIA, containing the amphibia pedata, or footed amphibia; and the serpentes, or footless amphibia. In the REPTILIA, there are four genera: 1. Testudo, tortoise, turtle. 2. Rama, frog, toad. , 3. Draco, dragon, or flying lizard. . 4. Lacerta, lizards, crocodile, chamae- leon, newt, salamander, iguana. Reptiles are characterized by breathing through their mouths; and by having feet, and flat naked ears; of this order are frogs, lizards, and tortoises. Serpents are distinguished as being without feet, but frequently armed with a deadly poison, contained in fangs resembling teeth. In cold and temperate climates they conceal themselves in winter in cavities beneath the surface of the ground, where they become torpid. Some serpents are viviparous, as the rat- tlesnake, the viper, &c.; but those which are innoxious are oviparous, depositing their eggs in a kind of chain in a warm situation, where they are afterwards hatched. The broad laminae on the bellies of serpents are termed scuta, and the smaller, or divided ones, beneath the tail, are called scales, and from these the genera are characterized. AMPHICROSTYLES, a temple with four columns in front, and four in rear. AMPHICTYONS, an assembly composed of deputies from the different states of Greece. AMPHISCII, those who inhabit the torrid zone. AMPHITHEATRE, an elliptical building, in which specta- tors assembled to witness spectacles of wild beasts, gladiators, &c. The nobility of Rome who courted popular favour, vied with one another in entertaining the people with these horrid amusements. Lucius Metellus, Pompey, Caesar, Augustus, and Vespasian, with his son Titus, all erected amphitheatres. Herod of Judea erected amphitheatres both at Jerusalem and Caesarea. During the reign of Tiberius, the amphitheatre of Fidenae fell, and buried in its ruins about 50,000 persons. AMPLIFICATION, the enlarging of a narration; and the soul of discourse with the ancients. AMPLITUDE, an arc of the heavens intercepted between the east and west point, and the centre of the sun or of a planet, when rising or setting; and so is either north or south, ortive or occasive. s AMPUTATION, the cutting off a limb, &c. See SURGERY. AMULET, a charm, talisman, or preventive against mis- chief, witchcraft, and diseases; and usually made of such stuff as the imagination of impostors, and the credulity of simple- tons, can devise: as, a stone, or a piece of metal ; an animal; the letters of the alphabet, &c. AMULet, To make an. Put a quarter of a pound of butter into a frying pan; break six eggs, beat them a little, and strain them through a hair sieve. Put them in when the butter is hot, and strew a little shred of parsley and boiled ham scraped fine, with nutmeg, pepper, and salt. Fry it brown on the under side : lay it on your dish, but do not turn it. Hold a hot sala- mander half a minute over it, to take off the raw look of the eggs: stick curled parsley in it, and serve it up. Some put in clary and chives, or onions. We have eaten Amulets made both ways; and a substantial dish they make,for a long journey. AMULET of Asparagus, To make an. Take six eggs, beat them up with cream; boil some of the largest and finest asparagus. When boiled, cut off the green and small pieces, and mix them with the eggs, and some pepper and salt.: make your pan hot, put in a slice of butter, then your eggs, &c. and send them up hot—on buttered toasts, if you please. AMYGDALUS, sweet or bitter almonds. See ALMo Nos. AMYLACEOUS, a term applied to the fine flour of farina- ceous seeds, in which consists their nutritive part. ANACLASTIC GLAsses, sonorous glasses, made chiefly in Germany. They resemble inverted funnels, whose bottoms are as thin as the peel of an onion; and upon applying the mouth : to the orifice, and gently sucking out the air, the bottom gives way with a crash, and the convex becomes concave. Breathe into the orifice, and the vessel becomes gibbous as before. ANACONDO, a large and terrible snake, found in Ceylon. ANAGALLIS, pimpernel; to the leaves of which many extraordinary virtues have been attributed. ANAGYRIS, bean trefoil. - ANALOGY, a certain relation or agreement between two or more things. In reasoning, analogy serves to explain or illustrate. Every physical resemblance may be reduced to two or more equalities; and every moral resemblance to two or more identities; and these are discernible only by intellect. ANALYSIS, generally speaking, the resolution of something into its constituent parts; in Mathematics, the method of resolving problems by means of algebraic equations, which consider, in a single line, what in the ordinary process would occupy pages. Analysis is divided into finite and infinite, determinate and indeterminate and residual. Analysis of powers. Analysis of curves, &c. Hence, ANALYST, one skilled in Algebra; and ANALYTICS, the science or doctrine of analysis. ANAMORPHOSIS, in Perspective and Painting, a mon- strous projection, or representation of some image, either on a plane or curve surface, deformed or distorted ; but which, in a cer- tain point of view, shall appear regular, and in just proportion. ANASARCA, a species of dropsy. ANASTATICA, the rose of Jericho. ANASTROUS SIGNs, in Astronomy, a name given to the duodecatemoria, or the twelve portions of the ecliptic, which the signs anciently possessed, but which have since been deserted by the precession of the equinoxes. ANATOMY, the dissection and study of the human body, which is a compound of solids and fluids. The solids are the bones, muscles, &c.; the fluids are the blood, secretions, &c. The bones are hard, white, insensible substances, full of spongy cells and neticular fibres. The bones of every skeleton are perfectly adapted to the extremity of those with which they are connected ; and this connexion forms what is called Articulation. The cartilages are white, smooth, solid, but elastic substances, whose number in the adult subject is less than in children. The periosteum, a fine membrane of a cel- lular texture, covers the bones at their joints, and is supplied with nerves, lymphatic vessels, &c. The marrow, a fat oily sub- stance filling the cavities of the bones, is supplied with nume- rous blood-vessels from the periosteum. The marrow seems to be to the bones what fat is to the muscles. The synovial glands lubricate the joints. The ligaments tie the bones together. The bursae mucosa are sacs capable of confining air or any other fluid ; they are placed between the tendons and the bones, or beyond these, and sometimes at the extremities, and they are lubricated by a liquid resembling that which lubricates the joints. The skeleton, divided into the head, trunk, and limbs, is merely an assemblage of the bones of an animal, united in their natural order. The common integuments, with their appendages, are the cuticle or scarf-skin, which invests the body every where, and covers the true skin. The rete muco- sum, is a mucous substance between the epidermis and cuticle, which gives colour to the body; for in negroes it is perfectly black, while the true skin is of the ordinary colour. The cutis, or true skin, is that from which leather may be made, and has throughout its whole surface innumerable papillae, calculated to receive the impressions of touch. Thus the rete mucosum keeps the cuticle and cutis soft, and the cuticle protects both. Insensible perspiration, or that subtile vapour exhaled from the body by the glands of the skin, becomes, by union and conden- sation from the atmosphere, drops of Sweat, which are analo- gous to urine in taste and nature. Accordingly, as either of A N (; A N C DICTION ARY OF ME CHANICAL SCIENCE. 39 these secretions is increased, the other is diminished. The nails cover and defend the exterior points of the fingers and toes, as hard transparent horns. The hair, growing from distinct bulbs in the skin, covers the head and different parts of the body. The cellular membrane and fat, are reservoirs of oily matter from the blood, that afford moisture to the parts with which they are connected. The muscles are the fleshy organs of motion; and are divisible into acute and insensible organs. The abdomen, or lower belly, contains the peritoneum, surrounding the viscera; the omentum is a cawl, or double membrane, interlarded with fat, and floating on the surface of the intestines; the stomach, a large bag lying across the upper part of the abdomen, which receives the aliment through the oesophagus cardia. The oesophagus, or gullet, resembles a funnel or canal, extending from the bottom of the mouth down to the diaphragm, or about the 11th or 12th vestebra of the back, where it terminates in the stomach. The intestines form a canal about six times the length of the body, extending from the inferior orifice of the stomach to the anus, being divided into two clásses, the large and small. The mesentery is a part of the peritoneum, situated amid the intestines. The pancreas is a conglomerate gland situated behind the stomach, and serving by its liquor to dilute the alimentary pulp, and to incorporate it more easily with the bile, The liver, a glandular substance formed for the secretion of the bile, is placed in the right hypochondrium, under the false ribs.-There are various other parts of the abdomen, which, in a popular work, may be advantageously omitted. The thorax, or chest, contains the breasts, the pleura, thymics, diaphragm, trachea, the lungs, the functions of respiration, and of voice. And under this division, surgeons reckon digestion, or the voiding of the feces; the peri- cardium; the heart and its auricles; the blood-vessels; arte- ries; glands and secretions; the brain nerves; the senses and their organs, as touch, taste, smelling, hearing, vision, &c. Comparative ANATOMY examines, 1st. The general variations in the organization and functions of animals. , 2d. The general relations which take place among the variations of organiza- tion and functions. 3d. The arrangement of animals founded on the general difference of their organization, ascending from the simplest to the most perfect structure; 4th, the anatomy of mammalia, or quadrupeds; 5th, of birds; 6th, of reptiles; ANCHOR, a crooked instrument of iron, dropped from a ship into the sea, to moor her to F.2.65. º) § are the two arms d, e, of equal £ || thickness with the beam b, which the flukes of the anchor, shaped like an isosceles A. The stock is which is a massive ring, to which the cable is fastened. Every ship chors. * Method of making Anchors.- is made of, be neither too soft nor too brittle, the latter rendering it the hole is made at one end of the shank for the ring, which is put into the hole of the shank, and the two ends shut together. |ollo I 7th, of fishes; 8th, of mollusca ; 9th, crustacea; 10th, insects; some particular station. In the is usually called the shank. The * a long beam of oak at f, consist- has three principal anchors, with a The goodness of an anchor is of {{Z_{Z Z/ UTV WTW fíſºfº liable to break ; and the former to 11th, worms; and 12th, zoophytes. . ANCHILOPS, a tumor near the inner angle of the eye. diagram, fig. 65, b is a strong bar of iron, at the lower end of which arms taper, and are fixed at an b angle of 30 degrees; g and h are ing of two pieces strongly bolted together, as seen in fig. 66; in cable to each; viz. the sheet, best bower, and small bower an- great importance, and care is therefore taken, that the metal it straighten. The shanks, arms, and flukes, are forged separately, then After which, the arms are shut to the shank one after the other, and the anchor is finished. Proof is made of anchors, as of coats of mail anciently, by raisi.g. them to a great height, and then letting them fall again on a kind of iron block, placed across for the purpose. To try whether the flukes will turn to the bottom and take hold of the ground, they place the anchor on an even surface, with the end of one of the flukes, and one of the ends of the Shank, resting on the surface: in case the anchor turns, and the point of the fluke rises upwards, the anchor is good. In England, France, and Holland, anchors are made of forged iron; but in Spain, and several parts of the South Sea, they are sometimes made of copper. For the proportions of anchors, the shank is thrice the length of one of the flukes, and half the length of the beam; or the length of the anchor is four-tenths of the greatest breadth of the ship. So that the Shank of an anchor, in a vessel 30 feet wide, must be 12 feet long. When the shank is eight feet long, the two arms are seven feet long, measuring them according to their curvity. As to the degree of curvity given the arms, there is no rule in it; the workmen are here left to their own discretion. The anchor of a large heavy vessel is smaller in proportion than that of a lesser and lighter one: because the sea employs an equal force against a small vessel as against a great one. Supposing the extent of wood upon which the water acts, to be equal in both, yet the smaller vessel, by reason of its supe- rior lightness, does not make so much resistance as the greater; the defect whereof must be supplied by the weight of the anchor. From hydrostatic principles, the following Table has been formed ; wherein is shewn, by means of the ship's breadth within, the proportions in length of the other parts of the anchor. In this Table is represented likewise the weight an anchor ought to be for a ship from 8 to 45 feet broad, increasing by the breadth of one foot; supposing that all anchors are similar, or that their weights are as the cubes of the lengths of the shanks. M. Bouguer directs to TABLE. take the length of the shank ^ Feet. ſ Feet, ſ Founds. in inches, and to divide the cube of it by 1160 for the 8 3} 33 weight, because the quo- 9 33 47 tient of the cube of 201 10 4 64 inches, which is the length 11 43 84 of an anchor weighing 7000 12 4; 110 Ib, divided by the weight, 13 5% 140 is 1160; and therefore, by 14 5% 175 the rule of three, this will . 15 6 216 be a common divisor for 16 6; 262 the cube of any length, and 17 64 314 a single operation will suf- 18 74 373 fice. The same author 19 73 439 gives the dimensions of the 3 | 20 . . b 512 several parts of an anchor, ? | 21 || 3 | 84 592 thus:–The two arms gene: 3 32 || 5 || 8: 681 rally form the arch of a cir- * | 23 || 2 || 2% 778 cle, whose centre is three- # | * | . # tº 884 eighths of the shank from F4 25 | r < 10 ;2 1000 the vertex, or point where 5 || 36 | | | 103 ; : 1124 it is fixed to the shank; 27 | < | 103 || > | 1259 and each arm is equal to 5 || 3 | = |}}} 1405 the same length, or the 3 || 3 || 5 || 11: 1562 radius; so that the two 3 || 39 || 3 | 12 1728 arms together make an * | *| | = | 12; 1906 arch of 120 degrees: the 32 12; 2097 flukes are half the length 33 13} 2300 of the arms, and their 34 13; 2514 breadth two-fifths of the 35 14 2742 said length. With respect 36 14% 2986 to the thickness, the cir- . . . 143 3242 cumference at the throat 38 15; 3512 or vertex of the 'shank, is 39 153 3796 generally made about a 40 16 4096 fifth part of its length, and 41 163 4426 the small end two-thirds of 42 163 4742 the throat; the small end 43 17, 5088 of the arms of the flukes, 44 17; 5451 three-fourths of the cir- U 45 U18 U 5832 40 º A N E A N D DictionARY OF MECHANICAL scIENCE. cumference of the shank at the throat. This dimension should be greater when the iron is of a bad quality, especially,if cast. iron is used instead of forged iron. AT. ANcholt, the situation of a ship when she rides upon. her, anchors.--An Improved Anchor Launch or Boat, for large ships has recently been invented. In the middle of the boat a bottomless well-hole is constructed in the form of a cross, of suitable dimensions to admit the flukes of the anchor (when in an upright position) down one of the arms of the cross, and the stock of the anchor down the other. In order to send out and drop an anchor, it is lowered down into the well-crop of the boat from the bow of the ship, and, thus sus- pended to the boat, it is secured by lashing, so that it may be cut away and dropped at the instant it is required. Previous to lowering the anchor from the ship into the boat, the cable is slackened out, and drawn up through the well-hole ; the anchor being then placed as before mentioned, the cable is fastened to the ring of it, in such manner as to be clear of the boat when the anchor falls. Several of these anchor launches are at present in use in the navy. ANchoR Ground, a bottom of sea neither too deep, too shal- low, nor rocky. In Architecture, anchors are ornaments among the borillons of the Tuscan, Doric, and Ionic capitals. In Heraldry, emblems of hope; either spiritual or temporal. ANCHUSA, yellow anchusa, or blue-flowered bugloss : the juice of its corolla, or flower, gives out to acids a beautiful green. An infusion of these flowers refresh the paticnt in hot, bitious, and inflammatory distempers. ANCONES, the corners or quoins of walls, cross-beams, rafters, &c. +. : - ANCYLOBLEPHARON, a disease of the eye, which closes the eyelids. If the cohesion! is on the cornea, the sight is inevitably lost. If the eyelids adhere to the eye, they are to be separated by a fine knife, and their re-union prevented by injections, and lint placed between them, after dipping it in some proper liniment.’ ANCYLOGLOSSUM, a contraction of the ligaments of the tongue: some have this imperfection from their birth; others from some disease. In the former case, the fraenulum may stretch by the child's sucking, or it may be snipped by a pair of scissars, but not torn by the finger: the ulcers must be cured by surgical assistance. ANCYLOSIS, a distortion or stiffness of the joints, caused by a settlement of the humours, or a distention of the nerves; and therefore remedies of a mollifying and relaxing nature are required. - ANDANTE, in Music, a movement moderately slow, be- tween largo and allegro. r l ANDRACHNE, bastard orpine. ANDROGYNOUS, in Zoology, an appellation given to animals which have both the male and female sex in the same individual. In Botany, the term is applied to such plants as bear both male and female flowers on the same root. ANDROIDES, in Mechanics, a figure constructed so as to. imitate the actions of man, as the automaton chess-player. See Chess. * , . Ess ANDROMEDA, in Astronomy, a constellation in the northern hemisphere, of which the chief is Almaac, a star of the second magnitude. The stars in this constellation are, in Ptolemy’s from the depending weight. catalogue, 23, in Tycho's 23, in Helvelius's 47, and in Mr. Flamsteed's not less than 66. Some of the stars or Andromeda. have been reckoned among the changeable stars, whose, brightness varies. - * ANDROMEDA, in Botany, March cystus. ANDROPOGON, in Botany, man's beard. ANDRYALA, downy sow thistle. ANEMONE, wild flower, which is gently astringent. ANEMOMETER, in Mechanics, fig. 68, implies a machine for measuring the force and velocity of wind. Various ma- chines of this kind have been invented at different times, and by diffcrent persons. The following has been often experi- enced, and found to answer the intentions. An open frame of wood, A B C D E FG H I, is sup- ported by the shaft or arbor I. In the two cross pieces H K, LM, is moved an horizontal axis Q M, by means of the four sails, a b, c m, of, gh, exposed to the wind in a proper manner. Upon this axis is fixed a cone of wood, M N C ; upon which, as the sails move round, a weight, R. or S, is raised by a string round its su- perficies, proceeding from the smaller to the larger end N O. Upon this larger end, or base of the cone, is fixed a rachet-wheel K, in whose teeth the click X falls, to prevent any retrograde The structure of this machine suffi- ciently shews, that it may be accommodated to estimate the variable force of the wind ; be- eause the force of the weight will continually increase as the string advances on the conical surface, by acting at a greater distance from the axis of motion; con- sequently, if such a weight be added on the smaller post M, as will just keep the machine in equilibrio in the weakest wind, the weight to be raised, as the wind becomes stronger, will be increased in proportion, and the diameter of the come N.O may be so large in comparison to that of the smaller end at M, that the strongest shall but just raise the weight at the greater end. If, for example, the diameter of the axis be to that of the base of the come NO, as 1 to 28; then if S be a weight of 1 pound at M on the axis, it will be equivalent to 28 pounds when raised to the greater end : if, therefore, when the wind is weakest, it supports one pound on the axis, it must be 28 times as strong, to raise the weight to the base of the cone. If, therefore, a line or scale of 28 equal parts, be, drawn on the side of the cone, the strength of the wind will be indicated by that number on which the string rests. It is well known to philosophers, that rain, on the presence or absence of which at the different seasons of the year, vegeta- tion, and the success of agriculture, in great measure depend, and also the temperature of the atmosphere, to whose influence both animals and vegetables are subject, arises from, or at least is strictly connected with, the various directions and velocities of winds. Nor has it escaped, observation, that the primary cause of the direction of the wind from a given Quarter, as well as of the velocity of its progress, is the rarefac- tion of the atmosphere in that tract towards which it blows. The reason why air does not rush in from all sides towards the rarefied tract, seems to me to be the inequality of its density in the surrounding tracts; for from that quarter, in which the mercury in the barometer stands highest, the air must pre- ferably proceed. If the density be, equal on, all sides, as in some confined tracts, a hurricane happens: hence the advan- tage of ascertaining and comparing the degrees of its velocity; for, those being known, its cause, and degrees of rarefaction, may with great probability be inferred, Two causes of rare- faction are already known, solar heat, and, some internal che- mical, action, by which a quantity of air is converted into water, and sometimes even into a stony substance; this last being ... Lºyºtº, or Wºy ſo- (ºl tº /*'.S. A-e == - tº | | º | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | sºlº º – = - = – e - = - == m --- --- L Illulºlºl - - - - A N E A N 9. DICTION A RY OF MECHANICAL SCIENCE. 41 the most sudden and complete, the rarefaction of the neigh- bouring air arising from it is by far the most violent, but com- monly of a much shorter duration and more limited extent. An accurate measure of the velocity of wind has long been sought by meteorologists. The force of wind, to which the degrees of its velocity are proportional, is measured by that of gravity, indicated in pounds and parts of a pound avoirdupois; the calculation is grounded on the observations of Mr. Smeaton, who indeed observes, that the evidence of the velocity is not so great where this exceeds 50 miles, as when 50 or under; yet, from its agreement with other observations, I am inclined to think it fully sufficient. A velocity of 123 feet per second was observed at Petersburgh, in 1741, that is, at the rate of 83.8 miles per hour. According to Lalande, the course of the trade-winds is between 6 and 7 miles an hour. Mr. Brice, (Philosophical Transactions, 1756, p. 226,) observed a storm whose velocity was 63 miles per hour. A fair wind at sea, is that whose velocity amounts to 20 feet per second, or 16.63 miles per hour. Bouguer found the velocity of winter storms to be about 34 miles per hour, and in summer nearly 43. Ibid. The distance from Holyhead to the Pigeon-house, Dublin Bay, is 70 miles ; then supposing the wind to be direct, and its velocity 30 miles per hour, and if we suppose the packet-boat to assume 0-4 of the velocity of the wind, it will arrive at the Pigeon-house in 58 hours. Let W denote the velocity of wind in the open air, or meeting no opposition; D = the distance of the place towards which the wind tends; N the number of hours it requires to traverse that distance ; then any two of these being known, the other may be found by the following formulas. Given. | Sought. | ID W. D. N. N = . Thus if W = 30, D = 70 º-sº then N = , = 2.33 w.N. p. p = y: I) – 30 × 2-33 - 70 D. N. w. w = i W = {}s = 30. A well-sailing ship assumes 4 the velocity of the wind. The best-sailing ship 0-4 of the wind's velocity. The above Formulas applied to the Calculation of a Ship's Way. Given. Sought. 0°4 W. D- N. : N = ºr, 0.4 W. N. D. D ~ 0.4 W N. D. N. 0-4 W. 0-4 W - . Thus the wind 30, and the distance 70 miles, then the number of hours requisite to traverse that distance will be 5'l for 30 x 0.4 = 12.0 and 12)70 = 5.8 hours. Again, 0.4 W being 12, and the hours, 5-8, being given, the distance 70 miles, we have 5-8 x 12 = 69.6, by the second formula. And lastly, the number of hours = 5:8, and space in miles = 70, being given, we have 0.4 of the velocity of the wind = {} = 12; and divid- ing this by 0.4, we have the rate per hour of its course in the lower atmosphere. Dr. Kirwan’s Anemometer. mometer, with a vane or weather-cock placed on the top, to shew the direction of the lighter winds, which could not be known by the anemometer, on account of the weight of the necessary appendages annexed to it. This is raised of a suffi- cient height above the building, supported by a vertical axis or pole ; the lower end of it passes through the roof and ceil- ing into an apartment below. Fig. 2. The lower part of the pole or vertical axis AA, fig. 1, more enlarged, to give a better view of the necessary appendages. The pole is made of a slender spar, such as are made use of for strong setting poles for lighters, and handles for boat-hooks, as not affected by lightning, which iron too often is, and the cause of the destruc- tion of buildings and many lives. To this pole is fastened a frame of light wood by screws, in which the weights are con- fined, one on the top of another, in grooves, in such a manner as to work up and down with the greatestfacility. The weights are connected together by cords, and marked 1, 2, 3, 4, &c.; the space between each, when drawn up by the force of the wind, is about one inch, as may be seen by the drawing, and (See Plate, fig. 1.) The ane- || * each weighs one pound avoirdupois. To the top weight is fastened a line, and passing along the pole to the top, and over a brass pulley fixed at the bottom of the square tube, under the sliding rod B, fig. 3, as far as a, and there fastened : in this sliding rod a groove or channel is cut underneath, to receive the line, so as not to impede its passage over the brass rollers, f. f. The line is composed of a number of common sewing-threads, laid in different directions, well waxed, and enclosed in a cotton case, to prevent as much as possible its extension or contraction by the changes of the atmosphere. Fig. 3. The wooden pipe or tube, two inches square, fastened on the top of the pole A A, fig. 1, open on the side, to shew the manner that the sliding rod B passes over the brass rollers f, f, f, when the wind is sufficiently strong to lift up one pound by its force on the square surface presented to it, as b and c, fig. 4. Fig. 4. The wooden pipe or tube, in which are enclosed the sliding rod, rollers, and line, from the effects of the weather. Fig. 5. The wooden frame, made of light wood, one foot square, covered over with very thin sheet brass, strongly painted, and varnished with copal. This frame is fastened to the sliding rod B, fig. 3, by means of a mortise, &c. Fig. 6. An enlarged view of the scale and index, which marks the greatest force of the wind during the absence of the observer, which is attached to the frame confining the weights, as G. H., fig. 2; and being connected with the hand fastened on the top weight (d fig. 2,) raises the small weight e ; and this being counterpoised by another of equal weight, by means of a line passing over a small pulley, as represented by this figure, and also G, fig. 2, occasions the small weight, with its index, to stop at the num- ber of pounds raised by the force of the wind, though they should fall down into their proper places on the wind’s abating. The bottom of the vertical axis or pole F, fig. 2, is sheathed with a steel point, and a socket, which rest on a wooden stand or frame, as at D, fig. 1, so as to turn with ease, and avoid as much as possible any friction. In order to render this simple machine more complete, and answer the purpose of an ane- moscope, as well as an anemometer, it is only necessary' to apply to that part of the pole or axis, which is in the apart- ment, an index, and attach to the ceiling a thin deal board, or a sheet of pasteboard, with the points of the compass marked thereon. A TABLE, Shewing the Velocity of the Wind in Miles per Hour, indicated by Avoirdupois Pounds and Parts. * * 1: 5 5 5 3. Fº Denomi- É. Fº Denomi- 5 Fº Denomi-l. ſºn- º º Ga sº 3 Parts. nations. 3 Parts. nations. 3 Parts. Inations, ! 0°492 32| 5-067 º 53| 13.923 — 11 || 0-615 33 5°386 X | Storm. 54|| 14-464 — 12| 0.738 * 34 || 5-705 55] 15:007 | — 13| 0-861 #3 ºn Great 56] 15:548 — 14|| 0.984 - 36|| 6′394 º | 57 | 16.089 || – 15 !...i. - 37| 6.763 \ |* |58|16,630 — #|##| || Biº || #: Rivergreat;|{{#| L. - - torm 60 | 17-715 - işliğ3 × gale. |40| 7.873 y |* |61| 18.403 || – 19| 1.795 - 41 §: Violent 62| 19.091 — 20 | 1.968 42 8-709 $ tempest. 63| 19.779 — 21 2-169 #| 3 ||37 || || Hurri. 64|20:467] — 22 || 2:370 Very |44. 9.545 ** 65 21:158! — 23| 2-571 brisk |45; 9.963 W | * 66| 21-846] — 24 2-772 gale. |46|| 10:430 67 22-534) — 25|2.975 - 47|10-897 68] 23-222 || – #|32% R High ſº 69| 23.910 — : ; $ wind. 49|11-831 70|24.602 — ;|:3 ||.T., ||...} - . . 30| 1.4% Veryº 52|13.382 31 4748 - W111 (i. Dr. Lind's Wind-gage.—This instrument consists of two glass tubes A B, CD, (See Plate, fig. 7.) of five or six inches in length. Their bores are about four-tenths of an inch in M 42 A N E A N É DICTIONARY OF MECHANICAL SCIENCE. diameter. They are connected together like a siphon by a small bent glass tube a b, the bore of which is about one-tenth of an inch in diameter. On the upper end of the leg A B there is a tube of latten brass, which is kneed, or bent perpendicu- larly outwards, and has its mouth open towards F. On the other leg CD, is a cover with a round hole G in the upper part of it, two-tenths of an inch in diameter. This cover and the kneed tube are connected together by a slip of brass e d, which not only gives strength to the whole instrument, but also serves to hold the scale HI. The kneed tube and cover are fixed on with hard cement or sealing wax. To the same tube is sol- dered a piece of brass, e, with a round hole in it to receive the steel spindle K L; and at f there is just such another piece of brass soldered to the brass hoop gh, which surrounds both legs of the instrument. There is a small shoulder on the spin- dle at f; upon which the instrument rests, and a small nut at i, to prevent it from being blown off the spindle by the wind. The whole instrument is easily turned round upon the spindle by the wind, so as always to present the mouth of the kneed tube towards it. The end of the spindle has a screw on it; by which it may be screwed into the top of a post, or a stand made on purpose. It has also a hole at L, to admit a small lever for screwing it into wood with more readiness and facility. A thin plate of brass, k, is soldered to the kneed tube, about half an inch above the ground-hole G, so as to prevent rain from falling into it. There is likewise a crooked tube A B, (fig. 8,) to be put occasionally upon the mouth of the kneed tube F, in order to prevent rain from being blown into the mouth of the wind-gage when it is left out all night, or exposed in the time of rain. The force or momentum of the wind may be ascertained by the assistance of this instrument, by filling the tubes half full of water, and pushing the scale a little up or down, till the zero of the scale, when the instrument is held up perpendicularly, be on a line with the surface of the water in both legs of the wind-gage. The instrument being thus adjusted, hold it up perpendicularly, and, turning the mouth of the kneed tube towards the wind, observe how much the water is depressed by it in the one leg, and raised in the other. The sum of the two is the height of a column of water which the wind is capable of sustaining at that time, and every body that is opposed to that wind will be pressed upon by a force equal to the weight of a column of water, having its base equal to the altitude of a column of water sustained by the wind in the wind-gage. Hence, the force of the wind upon any body where the surface opposed to it is known, may be easily found; and a ready comparison may be made betwixt the strength of one gale of wind and that of another. The force of the wind may be likewise measured with this instrument, by filling it until the water runs out at the hole G. For if it be then held up to the wind as before, a quantity of water will be blown out; and if both legs of the instrument are of the same bore, the height of the column sustained will be equal to double the column of water in either leg, or the sum of what is wanting in both legs. The use of the small tube of communication a b, (fig. 8,) is to check the undulation of the water, so that the height of it may be read off from the scale with ease and cer- tainty. But it is particularly designed to prevent the water, from being thrown up to a much greater or less altitude, than the true height of the column which the wind is able at that time to sustain, from receiving a sudden impulse whilst it is vibrating either in its ascent or descent. As, in some cases, the water in this instrument might be liable to freeze, and thus break the tubes, a saturated solution of sea-salt may be used instead of it in winter. Dr. Lind gives the following table, by means of which, from the observed height of the column of water in the gage, the force of the wind on a square foot may be determined, For heights not given in the following table, proportional parts are taken and added: for example, if the height be 5-5,-then to 26:040, the force for 5 inches, add 2,604 the force for 0'5, the decimal part, and the sum of the two, namely, 28.645 pounds, is the answer. When a saturated solution of salt is used, allowance must be made for the difference in the weight of the fluid. The specific gravity of the solution being to that of water as 1-244 to 1, the observed height of the column must be multiplied by 1-244. e Force of the Wind on . ... ............ Height of the Water *:: #. sº Common Designations in the Gage. in Pounds Avoird. of such Winds. 12 Inches . . . . . . 62.500 11 . . . . . . 57.293 º :::::: ; ; :::::: Most violent hurricane 8 . . . . . . 41'667 . . . . . . Very great hurricane. 7 . . . . . . 36'548 . . . . . . Great hurricane. 6 © e º e º e 31°750 . . . . . . Hurricane. 5 . . . . . . 26'041 . . . . . . Very great storm. 4. tº e º & e e 20.833 . . . . . . Great storm. 3 tº e º e 15:625 ...... Storm. 2 . . . . . . 10°416 . . . . . . Very high wind. 1 . . . . . . 5208 . . . . . . High wind. 0°5 . . . . . . 2'604 . . . . . . Brisk gale. 0 1 . . . . . . 0-521 . . . . . . Fresh breeze. 0'05 . . . . . . 0-260 . . . . . . Pleasant wind. 0.025 . . . . . . 0.030 . . . . . . A gentle wind. M. Bouguer's Wind-gage.—The instrument contrived by M. Bouguer consists of a hollow tube A A, BB, (fig. 9,) in which a spiral spring C D is fixed, that may be more or less compressed by a rod F S D passing through a hole within the tube at A A ; then having observed to what degree different forces or given weights are capable of compressing the spiral, mark divisions on the rod in such a manner, that the mark at S may indicate the weight requisite to force the spring into the situation C D : afterwards join at right angles to this rod at F, a plane surface EFE of a given area, either greater or less, at pleasure ; then let this instrument be opposed to the wind, so that it may strike the surface in the directions V E, V E, parallel to that of the rod, and the mark at S will shew the weight to which the force of the wind is equivalent. Dr. Brewster's Anemometer.—Dr. Brewster has suggested various contrivances for measuring the force of the wind. Among these we think the following, which indicates the force by its effect in compressing a column of air in a glass tube, is the most commodious and accurate. The metal cap A B, (fig. 10,) bent at a right angle, is fixed upon the top of the glass tube B C, which communicates at C with another glass tube, D E, of a much smaller bore, with a bulb, E, at its end. Some , mercury or other liquid, is poured into the tube B C, and of course rises to the same level, m, n, in both tubes. When the mouth A is exposed to the wind, the liquid at m descends in the tube, and by rising in the stem DE, compresses the enclosed air till there is an equilibrium between the elasticity of the air and the force of the wind. To prevent the fluid from oscillating, a thin disk of wood floats on its surface at m. The scale of this instrument, to ensure accuracy, should be formed by actual experiment. - Professor Leslie's Anemometer.—It would be improper to close this article without noticing the ingenious suggestion of this philosopher, for measuring the force of the wind by its cooling power. Having found, in the course of his experi- ments on heat, that the cooling power of a current of air is exactly proportional to its velocity, he derived from this prin- ciple the construction of a new anemometer, which will be understood without any figure, being, to use his own words, “in reality nothing more than a thermometer, only with its bulb larger than usual. Holding it in the open still air, the temperature is marked : it is then warmed by the application of the hand, and the time is noted which it takes to sink back to the middle point. This I shall term the fundamental mea- sure of cooling. The same observation is made on exposing the bulb to the impression of the wind, and I shall call the time required for the bisection of the interval of temperatures, the occasional measure of cooling. After these preliminaries, we have the following easy rule: Divide the fundamental by the occasional measure of cooling, and the excess of the quotient above unit, being multiplied by 4%, will express the velocity of the wind in miles per hour. The bulb of the thermometer ought to be more than half an inch in diameter, and may, for the sake of portability, be filled with alcohol, tinged, as usual, with archil. To simplify the observation, a sliding scale of equal parts may be applied to the tube. When the bulb has A N E A N G, DICTION ARY OF MECHANICAL SCIENCE, 43 acquired the due temperature, the zero of the slide is set oppo- site to the limit of the coloured liquor in the stem; and after having been heated, it again stands at 20° in its descent, the time which it thence takes until it sinks to 10° is measured by a stop-watch. Extemporaneous calculation may be avoided, by having a table engraved upon the scale, for the series of occasional intervals of cooling.” . - - [Other devices have been adepted by philosophical ingenuity, all of which we cannot even enumerate. Mr. Brice describes one, which has been successfully practised by himself, of mea- suring the velocity of the wind by means of that of the shadow of clouds passing over the surface of the earth.-Mr. Ons-en- Bray invented another, which of itself expresses on paper, not only the several winds that have blown during the space of twenty-four hours, and at what hour each began and ended, but also the different strength and velocities of each.] ANEMOSCOPE, fig. 69, a machine that shews either the course or velocity of the wind. The machine which shews the course of the wind, or from what point of the compass it blows, consists of an index moving about an upright circular plate, like the dial of a clock, on which the 32 points of the compass are drawn instead of the hours. The index which points to the divisions on the dial, is turned by a horizontal axis, having a trundle-head at its external extremity. This trundle-head is moved by a cog-wheel on a perpendicular axis; on the top of which a vane is fixed, that moves with the course of the wind, and puts the whole machine in motion. The whole contrivance is extremely simple, and nothing required in-the construction, but that the number of cogs in the wheel, and rounds in the trundle-head, be equal ; because it is necessary, that when the vane moves entirely round, the index of the dial also make a complete revolution. An anemoscope of this kind is placed in one of the turrets of the queen's palace. The anemoscope, calculated for indicating the force, or the velocity of the wind, is the same with what most writers call an anemometer; and we have, accordingly, described several of those machines under that article. We shall here add another, constructed by the late Mr. Pickering, and published in the Philosophical Trans- actions, No. 473. This anemoscope, 43 feet high, consists N # , ºs;–; - Ž Sºo € - ...< * d of jº ſº) ſº C: C & Fiz70. C º -Tº-Hº-Yº, | - (Z 1, § § { (1. of a broad and weighty pedestal, a pillar fastened into it, and an iron axis of about 3 an inch diameter, fastened into a pillar, Upon this axis turns a wooden tube; at the top of which is placed a vane, of the same materials, 21 inches long, consisting of a quadrant, quadrated and shod with an iron rim, notched to each degree ; and a counterpoise of wood, as in the figure, on the other. Through the centre of the quadrant runs an iron pin, up which are fastened two small round pieces of wood, which serve as moveable radii, to describe the degrees upon the quadrant, and as handles to a velum or sail, whose vane is one foot square, made of canvass, stretched upon four battens, and painted. On the upper batten, next to the shod rim of the quadrant, is a small spring, which catches at every notch cor- responding to each degree, as the wind shall, by pressing the sail, raise it up, and prevents the falling back of the sail, upon lessening the force of the wind. At the bottom of the wooden tube is an iron index, which moves round a circular piece of wood fastened to the top of the pillar on the pedestal, on which are described the 32 points of the compass. In fig. 69, this machine is shewn, where a is the pedestal ; b the pillar on which the iron axis is fitted ; c the circle of wood, on which are described the 32 points of the compass; e the wooden tube upon its axis; f the velum or sail; g the graduated quadrant; h the counterpoise of the vane. The adjoining figure, 70, a represents the velum ; b the spring; c c the wooden radii; d.d. the holes through which the pin in the centre of the quadrant goes. Its uses are the following:—1. Having a circular motion round the iron axis, and being furnished with a vane at the top and index at the bottom, when once you have fixed the artifi- cial cardinal points, described on the round piece of wood on the pillar, to the same quarters of the heavens, it gives a faith- ful account of that quarter from which the wind blows. 2. By having a velum or sail elevated by the wind along the arch of the quadrant to a height proportionable to the power of the column of wind pressing against it, the relative force of the wind, and the comparative power, at any two times of examina- tion, may be accurately taken. 3. By having a spring fitted to the notches of the iron with which the quadrant is shod, the velum is prevented from returning back upon the fall of the wind; and the machine gives the force to the highest blast, since the last time of examination, without the trouble of watch- ing it. The ingenious contriver of this machine tells us, that he carefully examined what dependence may be had upon it, during the storms of February 1743-4, and found that it answered exceedingly well; for that, in such winds as the sailors call violent storms, the machine had six degrees to spare for a more violent gust, before it comes to a horizontal position. It is certainly to be depended upon in ordinary weather, the velum being hung so tenderly, as to feel the most gentle breeze. There is, however, reason to fear, that the exposing of the anemoscope to all winds for a continuance, must disorder it; especially irregular blasts and squalls. It may not, therefore, be amiss, in violent squalis, for the observer to take the tube, with its vane and velum in his hand, in order to know the force of the wind ; and when he has finished his observations, to carry his machine into the house, till the violence of the storm is abated, when it may be replaced in its former situation. ANETHUM, dill and fennel. . ANEURISM, a throbbing tumor distended with blood, and formed by the dilation or rupture of an artery. ANGEIOTOMY, the opening a vein or artery. ANGELICA, To Candy. Angelica is cultivated only for the large ribs of its leaves, which are cut in May or June, and made into a candy as a medicinal plant. Take it when young, cut it in lengths, cover it close, and boil it till it is tender ; peel it, and put it in again, let it simmer, and boil till it is green; then take it up, and dry it with a cloth. To every pound of stalks put a pound of sugar: put your stalks into an earthen pan. Beat the sugar, and strew it over them. Let it stand two days; then boil it till it is clear and green : put it in a cul-, lender to drain. Beat a pound of sugar to powder again, and strew it on your angelica. Lay it on plates to dry, and set the plates in the oven after the pies are drawn. 34 lbs of sugar is the proportion to 4 lbs of stalks. ANGINA, an inflammation of the throat, called the quins.y. ANGLE, Angulus, in Geometry, is formed by the opening or mutual inclination of two lines meeting in a point; such is 44 A N I A N G DICTIONARY OF MECHANICAL SCIENCE. the angle BAC, or B.A. D.—Note. . B When an angle is denoted by three . letters, that at the angular point Jºž. must be read in the middle. But, . sometimes, for brevity sake, if there A -U. be but one angle at a point, that angle is denoted by the single letter standing at that point. ANGLEs are of several different kinds or denominations, as rectilinear, curvilinear, spherical, mixed, solid, &c. Rectilinear ANGLE, is that which is formed by the meeting of two right lines. Curvilinear ANGLE is that which is formed by the meet- ,” & * ,” '*, ..’ Jºž dº 22 's, ..,' £9. \ º Q ing of two curve lines. Mirtilinear ANGLE, is formed by the meeting of a right line and curve. Spherical ANGLE, is that which is formed on the surface of a sphere, by the intersection of two great circles. See SPHere and SPHERICAL Trigonometry. Solid ANGLE, is formed by the mutual inclination of more than two planes, or plane angles, meeting in a common point. See Solid ANGLE. Properties and Denominations of Rectilinear Angles.—Right ANG Le is that which is formed by B one line perpendicular to another; Rº, I) or that which is subtended by a .." quadrant of a circle; as the angle B.A. C. All right angles are equal to one another. An Oblique ANGLE * C is that which is greater or less than a . . A º right angle; and these are distinguished into two kinds, acute and obtuse. An Acute ANGLE is less than a right angle, as D A. C. An Obtuse ANGLE is greater than a right angle; as EAC. Adjacent ANgles, are the two angles formed by one line meeting another, any where, - 13 except at its extremities ; such Iſio.73. - are the two angles B.A. D., and 19./3. B A. C. These angles are said to be supplements to each other, " A. —& their sum . to ºright º angles, Vertical, or Opposite ANGLES, 7,” are such as have § legs mutual rºz_^ f{ continuations of each other; as _`A \l. B A C and D A C. Vertical, or op- - posite angles, are equal to each other, YS Alternate ANGLEs, are those made on the opposite sides of a line cutting two other lines; as A FG and D G F. And if these two lines are parallel, the alter- nate angles are equal. External ANGLES, are those formed by the sides of any right-lined figure, and the adjacent sides produced; such are the angles A, B, C, &c. The sum of all the external angles of any figure is equal to four right angles. Internal ANGLes, are the angles within a figure, formed by the meeting of each two adjacent sides; as the angles a, b, c, &c. The sum of all the inward angles of any right-lined figure, is equal to twice as many right angles, wanting four, as the figure has sides. An ANGLE at the Centre o a Circle, is that whose angular point is at the centre; such as the angle A C B. An ANGLE at the Circumference, is that whose angular point is in any part of the circumference; as the angle A D B. An angle of the centre is double an angle at the circumference, when both stand on the same arc. An ANGLE in a A Semicircle is an angle at the circumference contained in a semicircle, or standing upon a semicircle or diameter; and it is a right angle. An angle in a segment greater than a semicircle, is less than a right angle. An angle in a segment, less than a semicircle, is greater than a right angle. Angles of other denominations are used by some authors, as, the Horned ANGLE, formed by the circumference of a circle and a right line; Lunular ANGLE, formed by two curve lines, one concave and the other convex; and Cissoid ANGLE, the inward angle, formed by the intersection of the two spherical convex lines. quired. Problems.-1. To bisect a given Angle, B.A. C. From the centre A, with any radius, describe an arc cutting off the equal lines A D, A E ; and from the two centres D E, with the same radius, describe arcs intersecting in F, then draw AF; which will bisect the angle as re- B 2. At a given point A in the line AB, to make an Angle equal to a given Angle C. From - # the centres A and C, with T}^_Zºzy. Z2 Nº. Žty.8// any one radius, describe _º 49. *_*29 the arcs D E, B G ; then c i D A * with the centre B, and l; - radius DE, describe an arc cutting B G in G. Through G draw the line AG, and it will form the angle required. 3. To Measure the Quantity of an Angle on Paper.—Apply the centre of a protracter to the vertex of the angle, so that the radius may coincide with one of the lines; and the degree shewn by the other line, will give the measure of the angle required. . Otherwise with the Line of Chords.--With a radius equal to the chord of 60°, describe an arc between the lines forming the angle ; then apply the subtense of this arc to the same scale of chords, and it will give the measure sought. ANGLEs, in Astronomy, receive the following particular denomination: as ANG Le of Commutation, of Elongation, of Position, &c.; for which, see the respective terms. - ANG Les, in Mechanics and Optics, also receive particular denominations, and are distinguished into separate orders; as ANG Les of Direction, Elevation, Inclination, Inflection, Incidence, Refraction, &c.; for which, see the respective terms. Optic ANGLE, is the angle included between two rays, drawn from the two extreme points of an object to the centre of the pupil of the eye. ANGLING, among sportsmen, is the art of fishing, either with bait or flies, and a rod and line. The great secret of angling with bait is, to attract the fish to some particular spot by throwing in grains, chopped worms, &c. if the water is still; or if running, by enclosing a large quantity of worms in a tin box full of holes, by which the worms may crawl out and attract the fish. The anglers stand, sheltered by some bush or tree, as particularly at deep-water gullies, sluices, mill- dams, or ponds where the cattle go to water. Chub love deep shaded holes; eels are found under the banks of rivers and ponds; perch, in clear water and a swift stream; so are roach and trout found in quick currents; breams in deep quiet places. The best season for angling, is from April to October. A cloudy day, after a bright moonlight night, is good for fish- ing. Cool weather in summer, and warm weather in winter, are the fit seasons, from three till nine in the morning, and from three till sun-set in the afternoon. A southerly wind, in a dull warm day, is the best time of any ANGOLA PEA, pigeon pea. ANGOR, a concentration of natural heat; the consequence of which is, a pain of the head, palpitation, and sadness. ANGUINEAL HYPER BoLA. See HYPER BoLA. ANGULAR, something relating to, or having angles. Angular objects at a distance appear round. ANGULAR Motion, is that which is performed by an oscil- lating or vibrating body, as referred to the angle which it describes or passes over in a given time, the vertex of which is the point of suspension, or centre of motion. Hence all points in a pendulum have the same angular motion, although their absolute motions are different from each other, being greater or less, according to their distance from the centre of sus- pension. ANGULAR Motion is also sometimes used to denote a motion which is partly curvilinear, and partly rectilinear; as the motion of a coach-wheel on a plane. ANGULAR Sections, a term used by Vieta to denote a species of analytical trigono- metry, relating to the law of increase and decrease of the sines and chords of multiple arcs. • *-* ANIMAL, in Natural History, an organized and living body, endowed with sensation. Minerals increase; plants grow and live ; but animals have the power of locomotion, of seeking and appropriating nourishment, ... A N "I A N N 45 DICTIONARY OF MECHANICAL SCIENCE. ANIMAL Flowers, or Sea Nettle, or Sea Anemome, fig. 81, is a fleshy substance, en- dowed with claws, stomach, mouth, &c. and found adher- ing to rocks in the sea by *one end, and with the other voraciously devouring what- ever food comes in their way. ANIMAL Substances, in Che- mistry. The constituent prin- ciples of animal substances are nearly the same with those of the vegetables; the former, however, contain more of nitrogen and phosphorus; the latter, more of carbon and hydrogen. The complex constituent parts of animal sub- stances are the following: — 1. Gelatine. 2. Fibrin. 3. Al- bumen. 4. Animal oils. 5. Bone. , 6. Blood. 7. Milk. 8. Horn. 9. Phosphorus and animal acids.—Gelatine, or animal jelly, very generally dispersed through all the parts of animals, even in bones, exists in the greatest quantity in the tendons, membranes, and the skin.--Fibrin, or animal fibre, forming the basis of the muscular or fleshy parts of animals, is fibrous in its structure, transparent, and insoluble in water and alco- hol, except by a long continued heat in a Papin's digester.— Albumen is the principal constituent part of the serum of blood; it is also called coagulable lymph. The white of eggs consists almost entirely of albumen.—Animal oil, generally solid at the temperature of the atmosphere, contains more oxy- gen and sebacic acid, than the vegetable oils. Among animal oils may be ranked fat, tallow, lard, suet, butter, &c. Fish oil is generally more liquid than other animal oils. Spermaceti is an animal oil, found in the head of a species of whale.— Bones consist chiefly of phosphate of lime, with carbonate of lime, and gelatine.—Blood consists of albumen, fibrin, colour- ing matter, and a mild oil. The colouring matter has been supposed to depend upon iron, but Vauquelin has proved, that the most delicate test could not evince the existence of iron in it. Blood, when suffered to rest, separates into two parts, the one, a coagulum or clot, called the crassamentum ; the other, a fluid, called the serum.—Milk, if suffered to rest, throws upon its surface a butteraceous oil, called cream. If the remaining skimmed-milk be suffered to stand, it becomes sour, and sepa- rates into two parts: curd, which is chiefly albumen; and whey, (which is generally analogous to serum,) mixed with sugar and lactic acid.—Horn, &c. Nails, horns, hoofs, and quills, resemble coagulated albumen. are all animal substances of a complicated nature. ANIMAL Putrefaction. Every animal body, when deprived of life, and exposed to the air, undergoes a decomposition, or resolution of its parts. Its colour becomes pale, and then changes to blue and green; the parts become soft, and send out a putrid smell, from the discharge of noxious gas. The organi- zation is destroyed, the constituent parts of the animal sub- tances form new arrangements, and are chiefly resolved into a gaseous state; and what remains is.a dry powder, composed of earths and charcoal. ! ANIMALCULES, such animals as are clearly discernible only by means of microscopes, for millions of millions of them might be contained in a thimbleful of water, which is the best element for studying their motions. By the microscope many kinds of animalcules have been discovered, as different from each other as the horse from the mouse ; some indeed so exceedingly minute, that a million would not equal in magni- tude a large grain of sand; and, as more and smaller objects have ever been discovered, in proportion to the goodness of the glasses with which they have been viewed, it is highly pro- bable that there are numberless other species, of a size much less than those already discovered. Every drop of water, and almost any fluid, except oils and ardent spirits, either does or will, by standing exposed a few days in warm weather, swarm with living creatures. Some seem natural inhabitants of the fluids in which they are found; others live there only occa- sionally, in the manner of gnats, which, from eggs dropped in water by their parents, become swimming animals; but, after, a short time, shed their skins, appear in a form without resem- Bile, urine, saliva, &c. blance to that before assumed, take wing, and claim kindred with the countless millions which rejoice in the air. The largest sort are thin and transparent; they turn frequently, have many feet, often seen about the extremities; at one end are some bristles longer than the feet, resembling a tail. Their motion is swift, and their frequent turns and sudden stops would intimate that they were hunting after their prey, pro- bably insects indefinitely smaller than themselves, that have hitherto escaped notice with the best glasses. They employ their feet in both running and swimming ; for, putting a hair among them, like rope-dancers, they often creep along it, bending in odds postures. The second kind are spiral or screw-like : when they lie still, they often thrust forth a fringed or bearded tongue; a small current may be discerned towards them, probably caused by the nimble motion of some fins or legs, too minute to be discerned. Another sort, about the same size, but without tails, resemble a flounder : their feet may be seen clearly, as the water evaporates, when they move very nimbly. The next kind appear like slender worms, about fifty times longer than broad; their waving progressive motion is equal and slow. They swim with equal facility any way; and being every where of the same thickness, it is difficult to ascer- tain the head. A fifth sort are so small, that an hundred in a row would not equal the diameter of a grain of sand ; and consequently a million are but equal in bulk to one such par- ticle; their shape is nearly globular. A sixth kind have also been discerned, about the thickness of the last, but twice as long. . The smallest drop of sulphuric acid, only as much as will stick to the point of a pin, put among these animalcules, will cause them all to fall down dead. So eels in paste are very entertaining objects when examined by any microscope, particularly the solar one, which very plainly distinguishes the motions of their intestines; and, when the water is nearly evaporated, and they are near expiring, their mouths appear opened to a considerable width. Leeuwenhoek says, no living creatures appear in rain water fresh descended, but after standing a few days, innumerable animalcules of different spe- gies, many thousand times smaller than a grain of sand, are visible by the microscope. In summer, the water in ditches appears sometimes greenish or reddish; which, examined with the microscope, is owing entirely to the millions of animalcules. crowded on the surface. Their bodies are oval and transpa- rent, the middle parts either green or red; seem composed of globules, so similar to the roe of fish, that it is believed to be the same, especially as they are found, after some time, per- fectly clear and colourless, when they may be supposed to shed their spawn. The water from dunghills is so thronged with animalcules, that it seems all alive, and must be diluted before they can be separated to distinguish their kinds. ANNEALING, NEALING, the cooling of bottles and glass gradually by placing the materials thus blown in a furnace, in which they gradually cool. By the process of annealing, the glass is kept for some time in a state approaching to fluidity; the heatincreases the bulk of the crystallized part, and renders it so soft, that the internal parts have an opportunity of ex- panding, and forming a regular crystallization. A similar process is now used for rendering kettles, and other vessels of cast iron, less brittle. And as iron diminishes in bulk when it passes into a fluid state, the crystals of cast iron are destroyed by the blast of an air furnace, and the mass converted into forged iron, the particles of which it is composed having arranged themselves into that form of crystals or laminae, by which forged iron is distinguished. See IRON, &c. ANNO DOMINI, the year of our Lord; the computation of time from our Saviour's birth. ANNUAL, in Astronomy, any thing which relates to the year, or which returns yearly; as Annual Motion of the Earth, Argument of Longitude, Epacts, Equation, &c. ANNUITIES, signify any interest of money, rents, or pen- sions, payable from time to time, at particular periods. The most general division of annuities is into annuities certain, and contingent annuities; the payment of the latter depending upon some contingency; such, in particular, as the continuance of life. Annuities have also been divided into annuities in possession, and annuities in reversion; the former meaning such as have commenced, or are to commence immediately; |N 46. A N N A N 2'T DICTIONARY of MECHANICAL scIENCE. and the latter, such as will not commence till some particular future event has happened, or till some given period of time has expired. Annuities may be farther considered as being payable yearly, half-yearly, or quarterly. The present value of an annuity is that sum, which, being improved at compound interest, will be sufficient to pay the annuity. To find the present value of an annuity by the following TABLE, we have only to find the amount for £1 at the given rate of interest, and for the given time; which multiplied by the given annuity, or payment, will be the present worth–Example. What is the present value of an annuity of £40 per annum, to continue 20 years, at the rate of 4 per cent.” By the Table, the amount of £1 for 20 years, at 4 per cent. is 13:590326; therefore, 13.590326 × 40 – 6543. 12s. Very nearly. Table.—The present Value of £1 years, at any rate of Compound Interest from 3 to 6 per Cent. er Annum, and from 1 to 60 16 21 22 23 24 25 | 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 At 3 "| per Cent. 3# per Cent. 4 - per Cent. 4; per Cent. 5 per Cent. 6 per Cent. •970874 1-9 13470 2-82S61 I 3-7 16098 4.579708 5-4 1719 | 6-230283 7-019692 7-786 I 09 8°530203 9-252624 9.95.4004 10-634955 11:296073 11-937935 12°56'1102 13-166128 13°753513 14-323799 L4-87.7475 15:415024 15.936917 16°443608 I6'935542 I7-413148 I7 -886842 18-327.031 | 18-764108 19-188455 19-600441 20-000428 20-388765 20-765792 2, 1-131837 21-487.220 21-83.2252 22° 167235 22.492462 22:808215 23°114772 23:412400" 23°701359 23°981902 24-254274 24°518713 24*775449 25'02.4708 25°266707 25-501657 25°729764 |25'951.267 26°166240 26'374990 26-577660 26-77.4428 26°965464 27°150936 27-331005 27-505831 27.675564 •966184 1-8996.94 2-80.1637 3-673079 4°5.15052 5-328553 6'114544 6-873956 7,607687 8-316605 9-001551 9.663334 10-302738 I0-920520 11°517411 12-094117 12,651321 13-189682 13-709837 14-212403 14-697974 15-167125 15 602410 16-058368 16:48.1515 16-890352 17.285364 17-667.019 18,035767 18-39.2045 18.736276 19-068865 19-390,208 19-7.00684 20.000661 20-290494 20-570525 20-84.1087 21-102500 21-3550.72 21.509 104 21.834882 22-062689 22-2827.91 22.495450 22-70ſ)918 22.809438 23,091244 23-276564 23°455618 23°628616 23-7957.65 23.957260 24°113295 24-264053 24°409713 24°550448 24'68.6423 24-8.17800 24.944734 •961538 1,086095 2-77.5091 3-629895 5°24'2137 6.002055 6.732745 7-435332 8-110896 8.760477 9-385074 9,985648 10-563.123 11,118387 11,652296 12-165669 12,659297 13,133839 13.590326 14,029160 14°45'1115 14.856842 15-24.6963 I 5.622080 15-982.769 L6-329.580 16-66.3063 16-9837 15 17.292033 17-588494 17.873551 18-146674 18°4'11198 18-664613 18-908282 19-142579 19-367864 19°5844.85 19,792.774 19-993052 20-185627 20-370795 20-548841 20-720040 20-884652 21-042936 21-1951.31 21-341472. 21,482.185. 21-6174S5 21-747582 21.992057 22-108612 22-2198.19 (22.326749 22°4295.67 22-528430 22-623.490 4-451822 •956938 1-87.2668 2.748964 3•587526 4-389977 5-157872 5•892.701 6-595886 7-2687.90 7.912718 8-528917 9-118581 9-68.2852 10-222825 10-7395.46 11,2340 15 11-707 191 12-159992 12°593.294 13.007.936 13-404724 13-784.425 14-147775 14-495478 14-828209 15-146611 I 5-451303 15-74287.4 16-021889 16-288889 16-544.391 16-788891 17-022862 17-2467.58 17.46 1012 17-666040 17,862240 18-049990 I8-229656 18°401584 18°566109 18.723550 18°874210 19-018383 19-156343 19-288371 19°414709 19:53:5607 19-65.1298 19-762008 19.867.950 1996.9330 20-066345 20:159181 20-248021 20-333034 20-414387 20-492236 20-566733 20-638022 •952381 •1.8594.10 2.723.248 3•545950 4'3294.77 6-075692 5.786373 6°463213 7-107822 7-721735 8-306414 8-863252 9°393573 9°8986.41 10°37.9658 10-837770 II-274066 11.689587 12-085321 12°462210 12,821 li 3 13" | 63003 13°488574 13-7986.42 14:093945 14-375.185 14.643034 14'898]27 15-141074 15-372451 15:5928.10 15-80.2677 16-002549 16-192904 16:374.194 16'546852 16-7 11287 I6'867893 17-01704I 17° 159086 17:29.4368 17°423208 17°5459; 2 17-662773 17-774070 17-880066 17-98.1016 18.077158 18°1687.22 18°255,925 18-338977 18°418073 18°493.405 18° 1651.46 18°633.472 18°6985.45 18°760519 18°819542 18°875754 I8-929290 •943396 12S33393 2.67.3012 3-465,106 4-2 12364 4-917324 5-5S2381 6 209793 6.801692 7-360087 7-886875 8-383844 8-85.2683 9-294984 9-7 12249 .10°l 05895 10.477 260 10-827603 I 1-158116 Il-46993 l Il-764077 I2-04 1582 12.303379. 12:55.0358 12-783356 13-003166 13-210534 13°406 164 13.590,721 13-764831 13-929086 14-084043 ld-230230 14-368141 14:498246 14-620986 14.736780 14-S460 l 9 14-949075 15-046297 15-138016 15-224643 15-306173 15-383 182 l 5-4 558.32 15:52437 () 15,589028 15-656027 I 5-7 07:572 15,761861 15.8l 3076 | 5-86.1393 15.906974 15-949976 15.990543 l 6:02.8814 16,064919 16.0989S0 I6' 1311 13 I6-1 6 1 428 ANNULET, a small square member in the Doric capital, under the quarter round. * * ANODYNE, a medicine which eases pain, and procures sleep; as paregorics, which assuage pain; hypnotics, which pro- cure sleep; and narcotics, which relieve by causing stupefaction. ANOMALISTICAL YEAR, the period in which the earth passes through her orbit. The periodical year. ANOMALY, in Astronomy, an irregularity in the planets, whereby they deviate from the aphelion, or apogee. ANONA, the custard apple, cultivated in tropical climates on account of its fruit. ANONYMOUS, in Law, the sending letters without signa- ture, which is felony by the Black Act. *. ANSAE, the parts of Saturn's ring projecting beyond the disc.—ANSER, a small star in the milky way, between the Swan and Eagle. ANTARES, a star of the first magnitude, Cor Scorpii. ANTECEDENT, in Mathematics, the first of two terms of a ratio. - ANTECEDENCE, in Astronomy, an apparent motion of a planet towards the west, or contrary to the order of the signs. ANTESTATURE, in Fortification, a small retrenchment made of palisadoes, or sacks of earth, with a view to dispute with an enemy the remainder of a piece of ground. •. ANTHELIX, the inward protuberance of the external ear, being a semicircle within, and almost parallel to the helix. ANTHELMINTICS, medicines that destroy worms. ANTHEMIS, camomile, medicinally aperient, carminative, emollient, and in some measure anodyne: the flowers afford a shining yellow. . ANTHERA, that part of the stamina within the corolla, that contains the pollen, which, when mature, it emits for the im- pregnation of the plant. - ANTHERICUM, spider wort.—ANThoceros, horn flower. —ANTHolyzA, mad flower.—ANTHosper MUM, amber tree.— ANTHoxANTHUM, vernal grass. - ANTHROPOPHAGI, men-eaters, which have existed in all ages, and in many countries, where neither religion no philosophy enlighten the savage mind. - ANTHYLLIS, kidney vetch. ANTIDESMA, Chinese laurel. ANTIBILIOUS Pills; aloes, scammony, Turkey rhubarb, and tartarized antimony: one grain of each makes one pill. ANTIMONY, a mineral, so brittle as to be easily pulverized : it is of a whitish blue colour, is rarely ſound native, but generally combined with sulphur. Among the ancients it was in much repute as a dye for the eyelashes and eyebrows. As a medicine, it forms an emetic, when dissolved in wine and acetous acid. The tartaric acid forms with it tartar-emetic. In the arts, it is used to give the composition of burning mir- rors a finer texture : it renders the sound of bell-metal more clear; mingled with tin, it makes this last harder, whiter, and sonorous; mixed with lead, it makes printing types smooth and firm ; it purifies gold; and is employed in casting cannon balls.-For the brute creation, the virtues of antimony are highly extolled : it cures the measles in pigs, and purifies their blood: horses that have running heels are healed by it, by mixing one drachm of antimony with every feeding of oats you give the horse in the morning. When horses refuse it in oats, give it them in balls. Horses that look lean and scabby are soon fattened by a slight dose for two months every morning; and pigs also are fattened a fortnight sooner by having a few doses of antimony administered to them. - - ANTINOUS, in Astronomy, a figure inserted into the con- stellation Aquila, the Eagle. * ANTIPODES, those inhabitants of the globe that live diametrically opposite to each other. g ANTIRRHINUM, snap-dragon, or calve's snout, which is recommended in leprous, scrofulous, and hydropic cases. ANTISCORBUTICS, medicines good against the scurvy. ANTISEPTICS, such substances as resist putrefaction; as sea salt, nitre, salt of wormwood, alum, myrrh, asafoetida, terra. japonica, aloes; Jesuits’ bark, camomile, pepper, ginger, saf- ron, sage, rhubarb; valerian, mint, angelica, ivy; green tea, horse-radish, &c.; all the vegetable substances being dried. | ANTITHESIS, in Rhetoric, a contrast or opposition of A N X A P P 47 DICTION ATRY OF MECHANICAL SCIENCE. writers. - ANTONOMIASIA is another figure of speech, in which, for a proper name, is put the name of some dignity, office, profes- sion, &c.; as the king, or his majesty. ANTLIA PNEUMATICA, the Pneumatic Pump, is a novel asterism, which De la Caille formed out of a few stars between Hydra and Argo Navis. - - ANVIL, a smith's utensil, upon which he hammers his metal ; at one end is sometimes a spike or horn, and the sur- face must be very smooth and flat, and so hard that a file can make no impression on it: it is mounted on a block, the stump or root of a tree. There are small anvils used by locksmiths, which stand on their benches, &c. - AORTA, the artery which rises immediately from the left ventricle of the heart, and is from thence distributed to all parts of the body, by two grand trunks ascending and descending. ANXIETY, is a disagreeable sensation, quite different from pain, as being more obtuse, and less capable of being referred to any particular part, though frequently more intolerable than any pain. ... But we must take care to distinguish between anxiety in a medical sense, and that which is spoken of in common discourse. The latter does not at all depend on the state of the body, but belongs entirely to the mind; and arises from a sense of danger, or a foresight to any misfortune. The former is truly corporeal; and derives, no less than pain, its origin from a certain state of the body. Notwithstanding this difference, however, it is very possible for both these kinds of anxiety to be present at the same time, or for the one to be the cause of the other. A very great bodily anxiety will strike fear and despondency into the most resolute mind; and mental anxiety, on the contrary, if very violent and long-continued, may induce the former, by destroying the powers of the body, especially those which promote the circulation of the blood. Anxiety, in the medical sense of the word, arises in the first place from every cause disturbing or impeding the motion of the blood through the heart and large vessels near it; from diseases of the heart and its vessels, such as its enlargement, too great constriction, ossification, polypus, palpitation, Syn- cope, inflammation, debility, and also some affections of the mind. It is likewise produced by every diſficulty of breathing, from whatever cause it may arise; because then the blood passes less freely through the lungs: anxiety of this kind is felt deep in the breast. It is said also to arise from the diffi- cult passage of the blood through the liver or other abdominal viscera. A certain kind of anxiety is very common and trouble- some to hypochondriacal people; and arises from the stomach and intestimes being either loaded with indigested and cor- rupted food, or distended with air produced by fermentation, and extricated from the aliments. By such a load or disten- tion, the stomach, which is a very delicate organ, becomes greatly affected. Besides, the free descent of the diaphragm is thus hindered, and respiration obstructed. Anxiety of this kind is usually very much and suddenly relieved by the expul- sion of the air; by which, as well as by other signs of a bad digestion, it is easily known. In these cases the anxiety is usually, though with little accuracy, referred to the stomach. Anxiety also frequently accompanies fevers of every kind, sometimes in a greater and sometimes in a lesser degreer; arising as well from the general debility as from the blood being driven from the surface of the body, and accumulated in the large vessels: as in the beginning of an intermittent ſever. Or it may arise from an affection of the stomach, when over- loaded with crude, corrupted aliment, or distended and nau- seated with too much medicated drink. As the fever increases the anxiety of the patient becomes greater and greater; remarkably so, according to the testimony of physicians, either immediately before the crisis, or on the night preceding it; as before the breaking out of exanthemata, haemorrahagy, sweat, or diarrhoea, which sometimes remove fevers. The patient feels likewise an anxiety, from the striking in of any eruption or critical metastasis. This sensation also accompanies fevers and most other diseases, when the vital power is exhausted, and death approaches, of which it is the forerunner and the sign. It happens at that time, because the vital powers, unable to perform their functions, cannot make the blood cir- words or sentiments; and generally the ſavourites of young sº culate. But what kind of anxiety this is, the other signs of approaching death shew very evidently. Moreover, even in the time of sleep, anxiety may arise from the same causes: hence frightful dreams, which frequently disturb our repose with surprise and terror. - - APAUMEE, in Heraldry, a hand extended, the palm open, the fingers and thumb extended. APEPOIA, INDIG estion, which may be produced by abste- miousness and excess. Columbo root infused in a teapot with boiling water, and drank when cold in the forenoon, a wine- glass full at a time, is a very excellent dose when the stomach is languid. It is prescribed in substance with , any grateful aromatic, or infused in Madeira wine, now and then inter- posing gentle doses of tincture of rhubarb. . APERIENTS, facilitate the circulation, and remove obstruc- tions; smallage, fennel, asparagus, butcher's broom, and pars- ley, are the common aperients of the shops. APHANE, parsley root. - APHANIA, a total loss of voice, mostly the effect of other disorders, and must be removed by eradicating the disease which had caused it. APHELIUM, that point of a planet's orbit, in which it is farthest distant from the sun. t APHIS, the vinefretter, or plant louse, of which there are thirty-three species, all of them destructive to plants. r APHTHAE, small round ulcers in the mouth. 3. APHYLLANTHES, leafless flower. Blue Montpellier pink. APIARY, a place where bees are kept. See Bee. APIUM, parsley, which should be used sparingly, for it is liable to produce epilepsy in some constitutions. APOGEE, that part of the earth’s orbit which is farthest from the Sun. The sun's apogee and the earth's aphelion are one and the same point. APOGOGICAL DeMonstration ; See ABSURD ; an indirect way of proof, by observing the absurdity of the contrary. APOPHY GE, a concave ring of a column, above or below a flat member. - . . APOPLEXY, a disease by which the patient is suddenly deprived of all his senses, and of voluntary motion . APOSCYNUM, dog's-bane. * A POSTERIORI DeMonstration, proves or disproves the fact from the enumeration of particulars, as when we infer the rotundity of the earth from the circular shadow it casts on the II] OO II. - APOSTLES’ CReed, a formula of the Christian faith, occurs first in the writings of St. Ambrose ; and was introduced into the church about the end of the 5th century, when Petrus Gnapheus prescribed the recital of it every time divine service was performed. APOSTROPHE, in Rhetoric, a figure by which a person, who is either absent or dead, is addressed as if he were pre- sent, and listening to us. - • APOTHECARY, one who practises the art of pharmacy; in London, the apothecaries are one of the city companies; and they are obliged to make up their medicines according to rules laid down in the college dispensatory. Their hall, in Blackfriars, is the first laboratory in the universe. - APOTHEOSIS, the absurd ceremony of making a mortal a god. A gem in the museum of Brandenburgh, represents the apotheosis of Julius Caesar, mounted upon a celestial globe, and holding a helm in his hand, as if he were now the governor of heaven, as before of the earth. APOTOME, in Geometry, the difference between two im- measurable lines. In Music, the difference between a greater and lesser semitone ; expressed by the ratio 128: 125. . • APPARATUS, the appendages or utensils belonging to machines ; as the apparatus of an air-pump, electrical machine, &c.; meaning the various detached parts which are necessary for putting the machinery in action, and for performing experi- ments, &c. - - APPARENT, in Mathematics and Astronomy, is used to signify things as they appear to us, in contradistinction from real or true; and in this respect the apparent state of things is often very different from their real state : as is this case of distance, magnitude, &c. - APPARENT Conjunctions of the Planets, is when a right line. tº 48 A P P A P P DICTIONARY OF MECHANICAL SCIENCE, supposed to be drawn through their centres, passes through the eye of the spectator, and not through the centre of the earth.-And, in general, the apparent conjunction of any objects, is when they appear or are placed in the same right line with the eye. - APPARENT Diameter of an Object, is the angle that it sub- tends at the eye, which diminishes as the distance increases; so that a small object at a small distance may have the same apparent diameter as a much larger object at a greater distance, provided they subtend the same or equal angles at the eye. If the objects are parallel to each other, their real diameters are, in this case, proportional to their distances. The apparent diameter also varies with the position of the object; and of equal objects at equal distances, those which stand in a posi- tion most nearly perpendicular to the line of their direction from the observer, will appear to have the greatest diameter; our idea of the apparent magnitude generally varying nearly as the optic angle. But although the optic angle be the usual or sensible measure of the apparent magnitude of an object, yet habit, and the frequent experience of looking at distant objects, by which we know that they are larger than they appear, has so far prevailed upon the imagination aud judg- ment, as to cause this likewise to have some share in our esti- mation of apparent magnitudes; so that these will be judged to be more than in the ratio of the optic angles. APPARENT Altitude of Celestial Objects, is effected chiefly by refraction and parallax ; and that of terrestrial objects, by refraction. APPARENT Figure, the figure or shape which an object appears under when viewed at a distance; and is often dif- ferent from the true figure. Thus a straight line, viewed at a distance, may appear but as a point; a surface, as a line ; and a solid, as a surface. Also these may appear of different mag- nitudes, and the surface and solid of different figures, accord- ing to their situation with respect to the eye : thus the arch of of a circle may appear a straight line ; a square, a trapezium, or even a triangle; a circle, an ellipsis ; angular magnitudes, round; and a sphere, a circle. Also all objects have a ten- dency to roundness and smoothness, or appear less angular, as their distance is greater : for, as the distance is increased, the smaller angles and asperities first disappear, by sub- tending a less angle than one minute; after these, the next larger disappear, for the same reason; and so on continually, as the distance is more and more increased ; the object seem- ing still more and more round and smooth. So, a triangle, or square, at a great distance, appears only as a round speck; and the edge of the moon appears round to the eye, notwith- standing the hills and valleys on her surface. And hence it is also, that near objects, as a range of lamps, and such like, seen at a great distance, appear to be contiguous, and to form one uniform continued magnitude, by the intervals between them disappearing, from the smallness of the angles which they subtend. - APPAR ent Motion, is either that motion which we perceive in a distant body that moves, the eye at the same time being either in motion or at rest; or that motion which an object at rest seems to have, while the eye itself only is in motion. The motions of bodies at a great distance, though really moving equally, or passing over equal spaces in equal times, may appear to be very unequal and irregular to the eye, which can only judge of them by the mutation of the angle at the eye. And motions, to be equally visible, or appear equal, must be directly proportional to the distances of the objects moving. Again, very swift motions, as those of the luminaries, may not appear to be any motions at all, but like that of the hour-hand of a clock, on account of the great distance of the objects: and this will always happen, when the space actually passed over in one second of time, is less than about the 14000th part of its distance from the eye; for the hour-hand of a clock, and the stars about the earth, move at the rate of fifteen seconds of a degree in one second of time, which is only the 13751 part of the radius or distance from the eye. On the other hand, it is possible for the motion of a body to be so swift, as not to appear any motion at all; as when, through the whole space it describes, there constantly appears a continued surface or solid as it were generated by the motion of the object, as is the of the circle; as the body case when any thing is whirled very swiftly round, describing a ring, &c. Also, the more oblique the eye is to the line which a distant body moves in, the more will the apparent motion differ from the true one. So, if a body revolve with an equable motion in the circumference of the circle A B C D, &c. and the eye be at E in the plane moves from A to B and C, it seems to move slower … and slower along the Hino 2:...a.... ALK, till, when the body”. arrives at C, it appears at rest at K; then, while it really moves from C by D to F, it appears to move quicker and quicker from - K by L to A, where its motion is quickest of all ; after this it appears to move slower and slower from A to N, while the body moves from F to H.: there becoming stationary again, it appears to return from N to A in the straight line, while it really moves from H by I to A in the circle. And thus it appears to move in the line KN by a motion continually vary- ing between the least, or nothing, at the extremes K and N, and the greatest of all, at the middle point A. Or, if the motion be referred to the concave side of the circle, instead of the line KN, the appearances will be the same. All this is manifestly referable to the motions, stations, retrogradations, &c. of the planets. If an eye move directly forwards in one direction, any remote object at rest will appear to move in a parallel line the contrary way. But if the object move the same way, and . with equal velocity, it will seem to be at rest. If it move the same way, with less velocity, it will appear to move back- wards, with the difference of the velocities: if it move with *** * * • * * * - * * * •e -- * * - * e * - * e - greater velocity, it will appear to move forwards with the difference of the velocities. And when the object has a real motion contrary to that of the eye, it appears to move back- wards with the sum of the velocities. The truth of all this is experienced by persons in a boat moving on water, or in a moving carriage, making observations on distant objects in motion, or at rest. APPARENT Place of an Object, in Optics, is that in which it appears, when seen in or through glass, water, or other reflect- ing or refracting media. In most cases, it differs much from the true place. t APPARENT Station, in Astronomy, the position or appearance : a planet, or comet, in the same point of the zodiac for several ays. - APPARENT Heir, in Law, he whose right is indefeasible, provided he outlives the ancestor; as the eldest son, or his issue. HEIRs Presumptive, are those whose right of inherit- ance may be defeated by the contingency of some nearer heir being born. Thus, a second son or nephew may be heir pre- sumptive, but his right of inheritance may be defeated by the birth of a child to his elder brother or uncle ; or a daughter may be heir presumptive, as her hopes may hereafter be cut off by the birth of a son, who, by the English law, succeeds to both title and inheritance. * + APPARITION, in Astronomy, denotes a star or other luminary’s becoming visible, which before was hid: in which sense it stands opposed to Occultation. Thus the heliacal rising is rather an apparition than a proper rising. g APPEAL, in Law, the removal of a cause from an inferior to a superior judge; as from the ordinary courts to the House of Lords. - APPEARANCE, in Perspective, is the representation or projection of a figure, or body, upon the perspective plane. Direct APPEARANCE, in Optics, is the view or sight of an object by direct rays, without either refraction or reflection. In Astronomy, appearances are more commonly termed phe- nomena and phases. APPLE. There are many kinds of apples; the "golden pip- pin, which, though small, keeps well, and the tree grows well in good light soil; the Olsin pippin, or Arbroath, as to flavour, is outdone by none but the nonpareil; the Ribston pippin wilf keep till apples come again, and the tree grows in any situa- tion; the golden and royal russets are handsome apples, but A P R A Q U 49 DICTIONARY OF MECHANICAL SCIENCE, the nonpareil is the chief of the russets; the codlings grow freely, but none of them keep; the golden russet is a summer apple; the royal pearmain is large and beautiful. .. Apple Sauce for a Goose. Pare, core, and slice your apples, put them in a saucepan with as much water as...will keep them from burning; set them over a very slow fire. Keep them close covered till they are all of a pulp, them put in a lump of butter and sugar to your taste. Beat them well, and send them to table in a china-bason or sauce-boat, with a proper ladle. - • . APPLICATE: Ordinate APPLICAte, in Geometry, is a right line drawn across a curve, so as to be bisected by the diameter of it; being what we commonly call double ordinate. APPLICATION of GeoMETRY to ALG EBRA, is the converse of the first of the two succeeding cases; for as in that, algebra is employed in order to obtain the solution of a geometrical pro- blem, so in this case geometry is made use of to obtain the solution of an algebraical problem. This relates principally to the finding the roots of an equation by a geometrical con- struction, which is explained under the article Construction. Application of Algebra and Geometry to Mechanics, consists principally in representing, by equations, the curves described by bodies in motion; as in the theory of Projectiles, &c. * Application of Geometry and Astronomy to Geography, prin- cipally consists in determining by geometrical and astrono- mical operations, the figure of the terrestrial globe ; in finding the positions of places by their observed latitude and longi- tude; and in determining, by geometrical operations, the positions of places that are not very remote from one another. Astronomy and geography are again applicable to the theory of navigation. - g * APPRENTICE, one who is bound by covenant to serve a master, upon condition that he instructs or causes him to be instructed in his profession, art, or trade. Seven years is deem- ed the legal period; but from this there are many deviations. Several acts of parliament specify the obligations of masters and apprentices. The duties paid on indentures and premiums may be gathered from the enactments by which they are regulated. APPROACH, in Fortification, the works thrown up by the besiegers in order to get near a fortress without being exposed to the enemy’s cannon. In Gardening, it signifies the inoculat- ing or ingrafting the sprig of orie tree with another, without cutting it off the parent tree. - APPROXIMATION, in Algebra and Arithmetic, is the method of approaching nearer and nearer to the quantity sought, when there is no method of obtaining the exact value: this is the case in all rules for finding the square or cube root of any number that is not an exact square or cube. APRICOT. of this fruit we have several kinds; as, the more-park, or peach apricot, is a large handsome fruit, by many persons thought the richest of our stone fruits; the orange apricot grows freely, and is excellent for preserving; the Breda is juicy; the Brussels, juicy and high flavoured; the masculine, though small and sharp flavoured, is the earliest apricot we cultivate, APRIL, the fourth month of the year, according to the com- mon, but the second according to the astronomical computa- tion. It contains 30 days. In this month the sun travels through the sign Taurus; or more properly, the earth is now in Scorpio, and the sun, as seen from the earth, appears in Taurus. The APRIL Calendar, in animated nature, exhibits the viper and woodlouse; the mistletoe thrush pairs; frogs croak and spawn; and moths appear in the first week. In the second, the stone curlew clamours, young frogs appear, pheasant cocks crow, trouts rise, and spiders, creep plentifully. In the third week, the crested wren sings; blackbirds, ravens, pigeons, hens, and ducks, sit. In the fourth, the feldfare leaves us, and the swallow returns ; the mightingale sings, the bittern makes a noise; the house-martin skims the air, the blackcap whistles, and the common snake creeps abroad.—In vegetable nature, various shrubs and trees blossom, with the daffodil, hyacinth, wallflower, cowslip, periwinkle, ground ivy, beech and elm trees ; and the larch shoots its wiry leaves. Nursery men now sow for fruit-trees, forests and woods, and all sorts of profitable plantations in masses; those evergreens, the pine, fir, cedar of Lebanon, holly, and yew, are planted; and all the operations of routine culture, as hoeing, road-making, draining, cropping and fencing, are performed. The gardener grafts his fruit-trees; plants cuttings of gooseberry and currant shrubs; and trans- plants evergreens. The flower garden is cropped, slips and offsets are propagated, insects are destroyed, and the routine culture proceeds by weeding, hoeing, &c. Pleasure grounds and shrubberies are, now finished planting ; lawns are formed and repaired; the fires of the green-house are discontinued. In the kitchen garden, artichokes are dressed and planted ; asparagus beds are digged and forked, or sown; beans are planted and couthed up ; 'beet, brocoli, Brussels sprouts, cap- sicums, carrots, leeks, celery, onions, peas, Savoys, skirret, turnips, and salads, are sown; cabbages, cauliflower, German greens, potatoes, and seacale are planted. The cherry-house is forced ; the grapery is strictly attended to, established plants are forced in it; the forcing peach house, and the pinery and hot beds require all the gardener's care. Correct List of every thing in Season in April.–Meat. Beef, mutton, veal, lamb.-Fish. Carp, chub, tench, trout, crawfish, salmon, turbot, soles, skate, mullets, smelts, herrings, crabs, lobsters, prawns.—Poultry, &c. Pullets, fowls, chickens, duck- lings, pigeons, rabbits, leverets.-Roots, &c. Coleworts, Sprouts, brocoli, spinage, fennel, parsley, chervil, young onions, celery, endive, sorrel, burnet, tarragon, radishes, let- tuces, all sorts of small salad, thyme, and all sorts of pot- herbs.-Fruit. Oranges, lemons, forced cherries, apricots for tarts, grapes. A PRIORI, (demonstration 4 priori,) proves or disproves the fact from the law, or the effect from the cause ; as when we deduce the immortality of the soul from the fact, that the soul is a thinking principle, and that therefore it is immaterial and indestructible. APRON, in naval Architecture, a piece of curved timber fixed behind the lower part of the stein, and immediately above the foremost end of the keel. In Gunnery, the piece of lead that covers the touch-hole of a gun. APTERA, the seventh order of insects, and such as have no wings. AP US INDICA, the Bird of Paradise, a small asterism placed near the South Pole, contains eleven stars, none of which exceed the 4th magnitude. sº AQUARIUS, the 11th sign of the zodiac, through which the sun moves in the month of January. Aquarius is the Egyp- tian Canopus or Neptune, with his pitcher. Towards the end of July Aquarius sets with his head foremost, when the Egyp- tians fable, that he made the river Nile overflow by plunging his pitcher into it! This constellation is bounded on the north by Equuleus and Pegasus, east by Pisces and Cetus, south by Piscis Australis and Apparatus Sculptoris, and west by Capri- cornus and Antinous. There are 108 stars in this sign, four of which are of the 3d magnitude, six of the 4th, &c. The chief star a, of the 3d magnitude, having 1° 11' 22" south declination, and 329° 7' 43" right ascension, rises at London, on the east point of the horizon, and its rising and culminating on the first day of each month, are expressed in the following Table : Meridian Altitude 37° 17' 38”. MonTH. RISEs. (CULM. MONTH. RISES. CULM. ho. mi. ho. mi. ho. mi. ho. mi. Jan. 9 17 M. 3 20 A. || July. 9 32 A. | 3 12 M. Feb. 7 0 M. 1 0 A. || Aug. 7 30 A. | 1 8 M. Mar. 5 17 M. 11 11 M. Sept. . 5 30 (A. li i8 A. April. 3 27 M. 9 16 M. || Oct. 3 43 A. 9 28 A. May.' I 30 M. 7 15 M. Nov. ! I 45 A. 7 33 A. June. 11 27 A. 5 10 M. Dec. 11 34 M. 5 28, A. AQUA-TINTA FNGRAVING. By aqua-tinta engraving we can produce prints resembling drawings in Indian-ink. The prin- ciple of the process consists in corroding the copper with aqua fortis, so that an impression from it has the appearance of a tint of ink laid on the paper. This is done by covering the copper with a powder or some substance which takes a granu- lated form, so as to prevent the aqua fortis from acting where the particles adhere, and by this means causes it to corrode the copper partially, and in the interstices only. When these particles have been extremely minute, the impression from the plate appears like a wash of Indian-ink; but when they are large, the granulation is more distinct, and as this may be {} 50 A Q U A. Q. U DICTIONARY OF MECHANICAL SCIENCE. varied at pleasure, it may be adapted as successfully to a variety of purposes and subjects. This powder, or granula- tion, is called aqua-tinta grain; there are two methods of pro- ducing it. Having etched the outline on a copper-plate, pre- pared in the usual way by the coppersmith, procure some sub- stance finely powdered and sifted, which will melt with heat, and when cold will adhere to the plate, and resist the action of aqua fortis. The substances used for this purpose, either separately or mixed, are asphaltum, Burgundy-pitch, resin, gum-opal, gum-mastich ; and all the resins and gum-resins answer the same purpose. Common resin has been generally used, and answers tolerably; though gum-opal makes a better grain to resist the aqua fortis. The substance intended to be used for the grain is distributed equally over the plate; dif- ferent methods of performing this part of the operation have been used by different engravers. The usual way is to tie up the powder in a muslin bag, which is struck against a piece of stick, held at some height above the plate; the powder that issues out falls gently, and settles equally over the plate ; as hair powder upon the furniture, after the operations of the bar- ber. The plate being covered equally over with the dust or powder, the operator proceeds next to fix it upon the plate, by heating it gently, so as to melt the particles. This may be done by holding under the plate lighted pieces of rolled-up brown paper, moving them about till every part of the powder is melted; this will be known by its brownish change of colour. It is now to be suffered to cool, or be ready for the next part of the process. Such parts of the drawing to be engraved as are perfectly white, have their corresponding parts of the plate covered with turpentine varnish, diluted with turpentine to a proper consistence, to work freely with the pencil, and mixed with lamp-black to give it colour; if transparent, the touches of the pencil would not be distinctly seen. The margin of the plate, is also covered with varnish. When the varnish is dry, a border of wax is raised round the plate, as in etching, and you pour out the aqua fortis properly diluted with water. This is called biting-in. It is the part of the process most uncer- tain, and requiring the greatesi degree of experience. When the aqua fortis has lain on so long that the plate, when printed, would produce the lightest tint in the drawing, it is poured off, and the plate washed with water, and dried. When dry, the lightest tints in the drawing are varnished again, and the aqua fortis poured on as before, and the same process is repeated as often as there are tints to be produced in the plate. Although many plates are etched entirely by this method of stopping-out and biting-in alternately, yet in general it is very difficult to stop round, and leave out all the finishing touches, as also the leaves of trees and other objects, which in this manner it is impossible to execute with freedom. To over- come this difficulty, another process has been invented, by which these touches are laid on the plate with as much ease and expedition as in an Indian-ink drawing. Fine washed whiting mixed with a little treacle or sugar, and diluted with water in the pencil, so as to work freely, is laid on the plate covered with the aqua-tint ground, in the same manner and on the same parts as ink on the drawing. When dry, the plate is varnished with a weak thin varnish of turpentine, asphaltum, or mastich : when dry, aqua fortis is poured on. The varnish immediately breaks up in the parts where the treacle mixture was laid, and exposes those places to the action of the acid, while the rest of the plate remains secure. The effect of this is, that all the places where the treacle was used, are bit-in deeper than the rest, and have all the precision and firmness of touches in Indian-ink. After the plate is completely bitten-in, the bordering wax is taken off, by heating the plate a little with a lighted piece of paper; it is then cleared from the ground and varnish by oil of turpentine, and wiped clean with a rag and a little fine whiting, when it is ready for the printer. The disadvantages of this method of aqua-tinting are, a difficulty to produce the required degree of coarseness or fineness in the grain, and plates so engraved print not many impressions before they are worn out, and though occasionally of service, it is therefore seldom used. . The second method of producing the aqua-tint ground, generally practised, is the following. Some resinous substance, as common resin, Burgundy-pitch, or mastich, dissolved in spirits of wine, is poured, all over the the part which has the deepest shadows. obtain the practice of this art. plate, held in a slanting, direction that the superfluous fluid may drain off; it is then laid down to dry. The spirit, in evapo- rating, leaves the resin in a granulated state, or rather, the latter has cracked in every direction, still adhering firmly to the copper. A grain is thus produced with great ease, extremely regular and beautiful, and, in comparison of the former method, much superior for most purposes. After the grain is formed, every part of the process is conducted as described above. There are some particulars necessary to be known, to secure success in the operation. The spirits of wine used for the solution must be of the best quality, highly recti- fied. That sold in shops generally contains camphor, which entirely spoils the grain. Rosin, Burgundy-pitch, and gum- mastich, when dissolved in spirits of wine, produce grains of a different appearance and figure, and are sometimes used separately, and sometimes mixed in different proportions, according to the taste of the artist, some using one substance and some another. To produce a coarser or finer grain, it is necessary to use a greater or smaller quantity of resin ; and to ascertain the proportions, the liquor may be poured on several spare pieces of copper, and the grain examined, before it is applied to the plate to be engraved. When the solution is made, it must stand still and undisturbed for a day or two, till all the impurities of the rosin have settled to the bottom, and the fluid is quite pellucid. No other method of freeing it from those impurities has been found to answer: straining it through linen or muslin fills it with hairs, which ruin the grain. The room in which the liquid is poured on the plate must be per- fectly still, and free from dust, which whenever it falls on the plate while wet, causes a white spot, which it is impossible to remove without laying the grain afresh. The plate must also be previously cleaned carefully with a rag and whiting, as the smallest stain or particle of grease produces blemish in the grain. All these attentions are necessary, to produce regular grain; and, after every thing that can be done by the most experienced artists, there is still much uncertainty in the pro- cess. Artists are some times obliged to lay on the grains several times, before they procure one sufficiently regular. The same proportions of materials do not always produce the same effect, which depends greatly on their qualities; and it is even materially altered by the weather. These difficulties are not surmounted but by experience ; and those who daily practise the art, are liable to unforeseen accidents. It is to be lamented, that so elegant and useful a process should be so extremely delicate and uncertain. As the plate is held in a slanting direction, to drain off the superfluous fluid, there will naturally be a greater body of the liquid at the bottom than the top of the plate. Hence, a grain laid in this way is always coarser at the lowermost side of the plate. The most usual way is, to keep the coarsest side for the foreground, that being generally In large landscapes, various parts are sometimes laid with different grains, accord- ing to the nature of the subject. The finer the grain is, the more the impression resembles Indian-ink, and the fitter, it is for imitating drawings: but fine grains are apt to come off before"the aqua fortis has lain on long enough to produce the desired depth; and as the plate is not corroded so deep, it Sooner wears out in printing : coarser grains, on the contrary, are firmer, the acid goes deeper, and the plate throws off a greater number of impressions. This is evident when we con- sider, that, in the fine grains, the particles being small are near each other, and consequeutly the aqua fortis, which acts late- rally as well as downwards, soon undermines the particles, and causes them to come off. If left too long on the plate, the acid would eat away the grain entirely. The moderately coarse grains are on these accounts more sought after, and answer better than the fine grains formerly in use. Though there are difficulties in laying properly the aqua-tint grain, yet corroding the copper, or biting-in, so as to produce exactly the tint required, is even more precarious and uncertain. No rules can be laid down, by which success in this process can be secured; a deal of experience and attentive observation alone enable artists to do it with certainty. We will therefore give some hints which may be of importance to those who wish to The longer the acid remains in the copper, the deeper it bites, and consequently the darker A Q U A Q U Diction ARY of MECHANICAL scIENCE. 51 the shade on the impression. It may be of some use, therefore, to have several bits of copper laid with aqua-tint grounds, of the same kind to be used in the plate, and to let the aqua fortis remain for different lengths of time on each ; and then to examine the tints produced in one, two, three, four minutes, or longer. Observations of this kind, frequently repeated, and with acid of various degrees of strength, will assist the judg- ment in guessing at the tint to be produced in the plate. A magnifier is also useful, to examine the grain, and observe the depth to which it is bit. No proof of the plate can be obtained till the whole process is finished. Therefore if any part appears bit too dark, it must be burnished down with a steel burnisher; but this requires delicacy and good management, not to make the shade streaky; and as the beauty and durability of the grain are usually injured by it, it should be avoided as much as pos- sible. Those parts not dark enough, must have a fresh grain laid over them, and be stopped round with varnish, and sub- jected again to the aqua fortis. This re-biting requires care and attention. The plate must be well cleaned out with tur- pentine before laying on the grain, which should be pretty coarse, else it will not lay upon the heights only, as it is neces- sary to produce the same grain. If the new grain is different from the former, it will be rotten, not clear and fine.—In this general account of the process of engraving in aqua-tinta, we felieve no material circumstance has been omitted, that can be communicated, without seeing the different stages of the operation: but after all, no written directions whatever can enable a person to practise any art perfectly, much less engraving in aqua-tinta. Its success depends upon so many niceties, an attention to circumstances apparently so trifling, that the person who attempts it, must not be surprised if he does not succeed at first. It is a species of engraving simple and expeditious, if every thing goes on well; but precarious, and liable to errors which are rectified with great difficulty. It seems adapted for imitation sketches, washed, drawings, and slight subjects; but not at all calculated to produce prints from finished pictures. Nor does it appear suitable for book- plates, since it prints not a sufficient number of impressions. It cannot, therefore, be put in competition with the other modes of engraving; but, confined to subjects for which it is calcu- lated, it is extremely useful, as it is expeditious, and may be executed with much less trouble than any other mode of engraving. But even this circumstance is a source of mischief. It occasions the production of a multitude of prints, that have no other effect than that of vitiating the public taste. AQUEDUCT, a conduit of water, is a construction of stone and timber built on uneven ground, to preserve the level of water, and to conduct it through canals from one place to another. Some of these aqueducts are wisible, and others sub- terraneous: those of the former sort are constructed at a great height, across valleys and marshes, and supported by piers and ranges of arches; the latter are formed by piercing the mountains, and conducting them below the surface of the earth. They are built of brick, stone, &c. and covered above with vaulted roofs, or flat stones, serving to shelter the water from the sun and rain; and of these, some are double, and others triple, that is, supported by two or three ranges of arches. Of the latter kind, are the Pont-du-gard in Languedoc, supposed § have been built by the Romans to carry water to the city of ismes; that of Constantinople; and that which, according to Procopius, was constructed by Cosroes, king of Persia, near Petra in Mingrelia, and which had three conduits in the same direction, each elevated above the other. Some of the aque- ducts are paved, others convey the water through a natural channel of clay; and it was frequently conducted by pipes of lead into reservoirs of the same metal, or into troughs of hewn Stone. The AQUEDUCT of Alcantara, fig. 83, near Lisbon, is 56,380 feet long; supported on 127 arches, the middle arch being 220 feet high, and 108 feet wide; the other arches are extremely well executed; and in standing at the western angle, the eye ranges over the piers, without the slighest variations of any of them from the vertical plane. The joints are close, and the horizontal lines well preserved. The voussoirs of the arches appear of equal length, and their extrados are adapted to the courses of 16 inches deep. Those of the middle arch appear about 8 feet in length, and 15 of them constitute the depth of the work; but the four ranks of projecting stones, which pro- bably carried the centering, hurt the uniformity. The only perceptible sinking occasioned by the earthquake is in the north parapet, and in one of the towers. A stream, or rather winter-torrent, runs through the channel under the great arch, and empties itself into the Tagus, about two miles distant. The width of the section at top is 30 feet one inch, and at bottom 25 feet 10 inches. The steepest or eastern bank is the Lisbon side, and the gently rising or western bank, the Bellas side ; the spectator will then face the south. A statue of John V. who reigned in 1717, is represented in Roman costume on a pedestal on the eastern end, where the footpath com- mences, from which to the arch No. 1, is 570 feet seven inches solid wall. The most modern and most extensive aqueduct is that built by Louis XIV. near Maintenon, for carrying the river Bure to Versailles. It is 7000 fathoms long, and its elevation 2560 fathoms; and contains 242 arcades. Bridge of Alcantara-Fig. 83. ſt--n fi —f E-3 -º ti-º-º-t—º -s }: --- M-II- -s- \\ §§ º ". \ R Brčkº Š sº N \\ \ TN sº - W AES AN &A &S lºssº \\ W -] sºns §§W N ºğ § § WNS$ --- - - - EE a ſm ºf s m = = n = ess From Zisſon' EAST WEST’ § Š. & * s & & s 3%. . tº *ssº, Scale of Miles. * “ss. iod sº g ... nº ace age 400 sea goo zuz spe zoo was res... tºwe. Žsed run isog isoe..... moe redo Roo ===s- It is a very prevailing opinion, that the Romans, amidst all method of conducting and raising water by a train of pipes. their magnificence, were ignorant of the simplest elements of Nothing, however, can be worse founded than this notion. The hydrostatics, and therefore entirely unacquainted with the ancient writers, who either treat of the subject, or incidentally 52 A Q U A Q U DICTIONARY OF MECHANICAL SCIENCE. \ mention it, are clear and explicit in their remarks, while many vestiges of art still attest the accuracy of those statements, Pliny, the natural historian, lays down the main principle, that “ water will invariably rise to the height of its source :” Subit altitudinem exortus sui. He subjoins, that leaden pipes must be employed, to carry water up to an eminence, Palladius, in his treatise De Re Rustica, teaches how to find springs, by observing immediately, from the sunrise in the month of August, the vapours which hover above particular spots; and having there dug a well, he directs the water to be conducted to the farm or villa, either by a conduit constructed of masonry, or by means of pipes of lead, of wood, or even of earthenware, THe allows one foot in sixty, or in a hundred, for an uniform descent. But if the ground should afterwards rise, he says, the conduit must be supported on piles or arches, or the water must be raised in leaden pipes, when it will mount just to the level of its head. But Palladius testifies his aversion to the use of lead, as apt to become covered with ceruss, and thereby rendered unwholesome, or even poisonous. This consideration had, no doubt, served to restrain the general adoption of leaden pipes, among the Romans. Still, however, we may infer, from the allusions of the poets, that such pipes had come into very common use. . They were not cast tubular as at present, but consisted of thin plates bent up into the form of a cylinder, and soldered along the edge. They must fre- quently have given way, therefore, at this seam. Horace asks, if the water which threatens in the streets to burst its lead, be purer than the rivulet that trembles and murmurs as it flows. Epist. i. x. 20. Ovid compares, the gush of blood from the mortal wound which Pyramus, in the agony of despair, had inflicted upon himself, to the accidental rupture of a leaden pipe. Metam. iv. 120. Statius speaks; no doubt with poetical exaggeration, of whole rivers being discharged by such con- duits. Statius, I. Sylv. Vitruvius describes the three principal modes of conveying water; but directs, as the previous opera- tion, to trace a level (libramentum) on the ground. This libra- tion was performed by the dioptron, the water-level, or the chorobates. The dioptron seems to have been a sort of quad- rant fitted with sights; the water-level consisted of a tube, probably of copper, five feet long and an inch wide, turned up an inch and a half at both ends, and was adjusted till water rose equally in them; the chorobates, or perambulator, which he considered as the most accurate instrument, was composed of a rod twenty feet long, having a square and plummet attached at each extremity. Vitruvius allows only half a foot in the hundred, for the slope of an aqueduct. After the water had reached the walls of a city, it was admitted into a reser– voir or castellum, divided into three distinct and equal com- partments, one to feed the pools, and fountains, another to supply the public baths, and a third for the accommodation of palaces and private houses. The distribution of the water was effected commonly by means of leaden pipes. The smallest of these was called a denaria, being ten feet in length, the six- teenth part of this in breadth, and weighing 120 Roman pounds, This gives, for the thickness of the lead, exactly the quarter of an English inch. In lower situations, where the stress against the sides was greater, the pipes appear to have been made proportionally stronger. The quantity of water delivered from the cisterns was regulated by the dimensions of the spouts, termed calices. These formed a series of twenty-five different kinds, which served as moduli. Their diameters were some- times reckoned by ounces, or the twelfth parts of a Roman foot, but more commonly by quarter digits, or the sixty-fourth part of a foot. The quinaria seem to have been considered as the standard, and its width must have hence corresponded to the '906 part of an English inch. The ajutate or length of all those spouts was the same, being twelve digits, or three-fourths of a Roman foot, and therefore equal to 8-7 English inches. Prony conjectures, from very probable grounds, that such was also the altitude of a column of pressure above the middle of each orifice. This estimate gives 1979 cubic feet, for the quan- tity of discharge of a denaria, in the space of twenty-four hours. Leaden pipes were likewise employed to carry water across vales and over eminences. . But it behowed to erect, at the several incurvations, columnaria, or chimneys, to give vent to the air which might collect and gorge up the passage of the water. Such funnels required to be raised to near the height of the ſountain head. Vitruvius, however, joins with Palladius and Columella, in recommending pipes of earthenware, as not only cheaper, but more wholesome, than those of lead. They could be formed thicker, if necessary, and might be farther strengthened and secured, they said, by an outer coating of lime worked up with oil. But such pipes not being glazed, it became necessary, before using them, to fill up the pores by a sort of puddling, that is, to wash their inside with favilla, or fine wood-ashes. No wonder, therefore, that the leaden pipes were held in little estimation among the ancient Romans. They seem to have been seldom used indeed beyond the limits of the imperial city, except as auxiliaries in the smaller aque- ducts. When such conduits happened to be interrupted by a deep narrow vale, instead of joining them by an arch thrown over the gap, the connexion was sometimes formed by an inverted syphon of lead, carried on the one side down to the bottom, and brought up on the other. Rome was supplied by nine great aqueducts, according to Frontinus, who had been appointed curator of those magnificent works by the emperor Nerva. He added five more ; and the number was afterwards augmented, by successive emperors, to twenty. Of these, the most remarkable were, 1. The Aqua Appia, thus named from its having been constructed by the censor Appius Claudius, in the 442d year of Rome, begun between the sixth and eighth milestone, made a circuit of 880 deep paces, and then pro- ceeded by a deep subterranean drain of more than 11 miles, delivering the main body of its water in the Campus Martius. 2. The Old and New Anio, conduits so called from their bring- ing into Rome the waters of that river. The former began above the Tiber at the 30th milestone, and consisted mostly of a winding drain carried through an extent of about 43 miles. The latter, constructed under Nero, took a higher level, run- ning 7543 paces above ground, and then pursuing a subter- ranean passage of 54,267 paces in length. 3. The Aqua Mar- tia, which owed its formation to Quintus Martius, rose from a spring, distant 33 miles from Rome, made a circuit of three miles, and afterwards, forming a vault of 16 feet diameter, it ran 38 miles along a series of arcades at the elevation of 70 feet. It had vents perforated at certain distances, for disgorg- ing the collected air; and the conduit was occasionally inter- rupted by deep cisterns, in which the water settled and depo- sited its sediment. It was hence remarkable for its clear green colour. Lib. xxx. 5. The Aqua Julia and the Aqua Tepula were brought by the same aqueduct, only in two lower conduits. 4. The Aqua Virginia, conducted by Agrippa, the patriotic lieutenant of Augustus, who laboured to improve and beautify Rome; and who, according to Pliny, formed in one year 70 pools, 105 fountains, and 130 reservoirs. It commenced at a very copious spring, in the midst of a marsh, at the distance of eight miles from the city, and ran about 12 miles, passing through a tunnel of 800 paces in length. 5. The Aqua Claudia, begun by Nero, and completed by Claudius, took its rise 38 miles from Rome; it formed a subterranean stream 363 miles in length, ran 103 miles along the surface of the ground, was vaulted for the space of three miles, and supported on arcades through the extent of seven miles, being carried along so high a level as to supply all the hills of Rome. It was built of hewn stone, and still continues to furnish the modern city with water of the best quality, which has hence procured it the name of Acqua Felice. The practice of tunnelling was begun under Augustus, who greatly extended the aqueducts. Other emperors likewise directed their attention to that important object. Trajan shewed particular solicitude in improving the aqueducts. Those works were executed in the boldest man- ner; nothing could resist the skill and enterprise of the Romans; they drained whole lakes, drove mines through mountains, and raised up the level of valleys by accumulated arcades. The water was kept cool by covering it with vaults, which were often so spacious, that, according to Procopius, who wrote in the time of Belisarius, a man on horseback.could ride through them. . So abundant indeed was the supply, as to induce Strabo to say, that whole rivers flowed through the streets of Rome. Contémplating the utility, the extent and grandeur of those aqueducts, Pliny justly regarded them as the wonder of the world. Plin. xxxvi. 15. The same idea is A Q U A. R. B. 53 DICTIONARY OF MECHANICAL SCIENCE. expressed by the poet Rutilius. Rutilius in Itin. According to the enumeration of Frontinus, the nine earlier aqueducts deli- vered every day 14,018 quinaria. This corresponds to 27,743,100 cubic feet. We may therefore extend the supply, when all the aqueducts were in action, to the enormous quantity of 50,000,000 cubic feet of water. Reckoning the population of ancient Rome at a million, which it probably never exceeded, this would furnish no less than fifty cubic feet, for the daily con- sumption of each inhabitant. ... In modern Rome, three aque- ducts, the Acqua Felice, Juliana, and Paulina, with some additional sources, deliver in twenty-four hours, according to the calculation of Prony, 5,305,000 cubic feet. This, shared among a population of 130,000, gives about forty cubic feet for each individual, being nearly the same comparative supply as in the period of Roman splendour. Such profusion of water altogether transcends our conceptions. The supply of London in the year 1790 was only 2,626,560 cubic feet daily; and even now, when the rivalship of the several water companies has almost deluged the streets, it amounts only to 3,888,000 cubic feet. This quantity is abundantly sufficient for all the wants of a luxurious mass of inhabitants, equal certainly to the popu- lation of ancient Rome, where the consumption, however, was still fourteen times greater. How paltry then appears the actual supply of Paris, amounting only to 293,600 cubic feet of water in a day. It affords scarcely half a cubic foot, or thirty pounds avoirdupois, to each inhabitant in a population of 600,000. The Greeks of the Lower Empire had simplified the general mode of conducting water. This evidently appears from the practice which now prevails in supplying the city of Constantinople. The ground is levelled by means of the Terazi, a sort of inverted mason’s plummet, which hangs from the middle of a cord stretched between two rods divided into inches and parts, set upright, and removed successively from one station to another. But the chief improvement con- sists in substituting, for the columnaria of the Romans, the Souterazi or water-balance, a sort of hydraulic obelisk or pyramid. By this ingenious contrivance, the expense of aqueducts is reduced to a fifth part. ... The water runs down with a gentle slope in covered drains, till it reaches an obelisk constructed of masonry; and rising up the one side, by a nar- row channel, discharges itself into a basin at the top, from which again, at a level eight inches lower, it descends by a similar channel on the other side. The form of this hydraulic pyramid may be easily represented by the reader, without the aid of any diagram to assist his conception. Such auxiliary machines, which facilitate the escape of the air, and allow the water to settle, are commonly erected at intervals of about two hundred yards. The system is, in fact, only a repetition of conduits. From each separate basin, the water is distributed by orifices of different diameters, but having their centres all in the same horizontal line, three inches beneath the brim. The charge of the waterworks at Constantinople is intrusted to a body of 300 Turks and some Albanese Greeks, who form almost an hereditary profession. According to the interesting work of General Andreossy on the Bosphorus, that for the supply of a population of 600,000 is only two-thirds of a cubic foot, or about forty pounds of water per day. There still remain at Constantinople two ancient cisterns: 1. The Subterranean cistern, built of hard brick, vaulted and resting on marble columns: and 2. The cistern of one hundred and one columns, called anciently Philoxene; it consists of three rows of columns, one above another, and capable of holding five days' supply for the whole inhabitants of this spacious city.—Leslie’s Natural Philosophy. * AQUILA, a constellation in the northern hemisphere, usually joined with Antinous. assumed when he carried to mount Ida the beautiful Gany- mede, son of Tros, king of Phrygia. Antinous was a youth of Bithynia, (now Anatolia, in Asia Minor,) a great favourite of the emperor Adrian, who erected a temple to his memory, and placed him among the constellations. The asterism Antinous is generally considered an integral part of the constellation Aquila. Athair, the chief star, and of the first magnitude, is situated in the eagle's neck; its right ascension is 295°29'48"; 'and its declination is 8° 23'57". It appears on the E.N.E. According to some ancient poets, this eagle is the same as that whose form Jupiter. three-fourths east point of the horizon, at London, and rises and culminates as in the following Table: Meridian Altitude, 46° 52' 57". RISES. - MonTH. | RISES. CULM MONTH. CULM. ho. mi. ho. mi. . ho. mi. ho. mi. Jan. 6 5 M. 1 0 A. || July 6 25 A. | 1 0 M. Feb. 3 50 M. 10 35 M Aug. 4 25 A. | 11 0 . A. Mar. 2 10 M. 8 50 M. Sept. 2 25 A. | 9 0 A. April 12 16 M. 6 50 M. Oct. I2 31 A. | 7 15 A May 10 30 A. | 5 0 M Nov. 10 35 A. | 5 25 A. June 8 25 A. | 3 0 M Dec. 8 25 M. | 3 || 5 A. AQUILEGIA, columbine, the leaves, flowers, and seeds of which were formerly in great repute among the people for throwing out the small pox and measles. ARA, the Altar, an asterism south of the Scorpion's Tail, contains nine stars, of which three are of the third magnitude, four of the fourth, &c. The chief star culminates *g, * nearly at the same time with Ras Kigothi in the *%.” head of Hercules. See HERCULES. & ARABIS, bastard tower wall-cress. - ARABLE LANDs, those which are fit for til- lage, or have been tilled. Jº ARACK, or INDIAN ToDDY, the juice of the cocoanut tree; or a distillation of rice fermented with toddy. The Tartars have a species of arack distilled from mare's milk. ARAEOMETER, or WATERPoise, fig. 82, an . instrument to measure the density or gravity of fluids, is usually made of glass, a round hollow ball terminating in a long slender neck, herme- tically sealed at top, there being first as much running mercury put into it as will keep it swim- ming in an erect position. The stem is divided into degrees, and by the depth of its descent into any liquor, the lightness of that liquor is ascertained, for that fluid in which it sinks least must be heaviest: and that in which it sinks lowest, lightest. See HYDRom Eter. - * = ARBOR, a tree, in Botany. In Mechanics, the principal part of a machine which serves to sustain the rest. ARBOR DIANAE, or Tree of Diana. Half an ounce of finc silver, and two drachms of mercury, dissolved separately in a quantity of aquafortis, are then mixed together, and poured into a pint of common water, and stirred about, that the whole may be well mixed. This preparation is kept in a bottle well corked. In a glass globe, or other vessel, put the amalgam of silver with mercury, the quantity of a small nut; pour three or four ounces of the above liquor over it, and, some hours after, there will arise from the globular amalgam small branches, which, by increasing, will form a beautiful silver shrub. AR BoR MARTIs, or the Tree of Mars. Dissolve iron filings in aquafortis moderately concentrated, till the acid is satu- rated : then add to it gradually a solution of fixed alkali, (oil of tartar per deliquium.) A strong effervescence will ensue, and the iron, instead of falling to the bottom of the vessel, will afterwards rise, and cover the sides, forming a multitude of ramifications heaped one upon the other, which will pass over the edge of the vessel, and extend themselves on the outside with all the appearance of a plant.—Silver Tree on Glass. Put a few drops of the solution of silver in aquafortis on a piece of glass, form a bit of copper or brass wire to represent a tree with its branches, but flat, so as to lie upon the glass; lay it in the liquid, and let-it remain for an hour or two. A beautiful vegetation will be perceived all round the wire, which will nearly be covered by it. This may be preserved by washing it very carefully with water, and putting another glass over it.— Lead Tree. Dissolve an ounce of sugar of lead in a quart of clear water, put it into a glass decanter or globe, then suspend in the solution, near the top, a small piece of zinc of an irre- gular shape. Let it stand undisturbed for a day, and it will begin to shoot out into leaves, and apparently to vegetate. If left undisturbed for a few days, it becomes extremely beauti- ful : but it must be moved with great caution. It may appear to those unacquainted with chemistry, that the piece of zinc actually puts out leaves; but this is a mistake; for if the zinc be examined, it will be found nearly unaltered. This pheno- P 54. A. R. C. A R & DICTIONARY OF MECHANICAL SCIENCE. menon is owing to the zinc having a greater attraction for oxygen than the lead has; consequently, it takes it from the oxyde of lead, which re-appears in its metallic state. ARBUTUS, or Bear her:RY. Its leaves are employed either as a powder or decoction, in gravelly complaints. Boiled in an acid, these leaves will dye brown. - ARCADE, an opening in the wall of a building formed by an arch : thus, in London, there is the Burlington arcade; the Royal arcade, a dismal passage behind the Opera House. ARCH, a portion of the circumference of a circle, or curved line; yet arches are sometimes straight lines, as the beautiful arches of the portico of St. Andrew’s Church, Glasgow, than which there is not a finer piece of architecture in the kingdom. Triumphal ARches are magnificent entries into cities; as the arch of Titus (see the Plate,) and that of Constantine, at Rome; the gate of St. Dennis, Paris, &c. In fig. 84, A S'ES B is the ponderating arch; A or B the spring of the arch; D its crown; A B its span ; CD its height, or versed sine, or rise; A D B the intrados, or the lower surface of the arch, (often called the arch); S E S the extrados, being in bridges the superior surface, or the road- way; F F the flanks or lances; the spaces above these are called the spandrells; the portions of stone resemblingwedges, whichlie #.". • ... Definition of an Arch. intrados, are - called vous- soirs, or arch stones; at D ... S § - the key-stone: 'º-N -ºvº[-,-,-, Jº F-T. the *Tš. -T *S* D T-S4 . . ." masses P • - º,. KXN ..., | Pr0'T'S', built r - *XX*. to support the R-TE B { } N arches, and || || || | i Fig& E from which h #.i. as - - theirbases,are º - I either called- Q’ P R e H a k piers or abutments: piers, when they stand between two neigh- bouring arches; and abutments, when they support the arches which are contiguous to the shore : the part of the pier from which the arch springs is called the impost; the curve formed by the upper sides of the voussoirs, the archivolt; and the lines F'S', FS, about the flanks, in which a break is most likely to take place, the joints of the fracture. - ARCHERS, the royal company of, in Scotland, are his majesty’s body guards within seven miles of Edinburgh; and upon the visit of his majesty George IV. to this part of his dominions, the royal company of archers, 1000 strong, dressed in their tartan white and green, with their standards, &c. were acknowledged and received as the body guard of the sovereign, 1822. They claim this privilege by a statute of James I. 1603. ARCHES COURT, an ecclesiastical court of appeal, belonging to the archbishop of each province. ARCHIL, purple rock lichen, grows upon rocks in Eng- land and Wales, and when properly prepared, imparts to woollen cloth a reddish brown ; or dull, but durable crimson. It is sometimes used as a styptic. ARCHIMEDES, of Syracuse, one of the greatest and most celebrated of the ancient mathematicians, was born in the above city about 240 years before Christ. The great and com- prehensive genius of this author led him to the study of every branch of science; arithmetic, geometry, mechanics, optics, hydrodynamics, were alike the objects of his investigations, and experienced alike the powerful effects of his superior talents. To Archimedes we owe the first idea of the specific gravity of ‘bodies, which arose out of the following circum- stance. Hiero, king of Syracuse, having had reason to suspect that a goldsmith, who was employed to make him a crown of gold, had adulterated the metal by mixing with it a quantity of silver, requested Archimedes to endeavour to discover the cheat; which he did, by procuring two masses of gold and silver of equal weight with the crown, which he immersed in a vessel full of water, and carefully noticed the quantity of water which each displaced ; after which, he observed how much the | crown caused the same water to flow over; and on comparing this quantity with each of the former, he was able to ascertain the proportions of gold and silver in the crown. He is the reviver at least of the Egyptian mechanics. - ARchi Medes' Screw, fig. 85; or ºther water snail, is a machine for raising water, consisting of a “flexible tube rolled . . . . • * in a spiral form round a cylinder, : as in the figure. The water enters at C, and de- scends at first in the spiral canal by its specific gravity, but the cylinder being turned, the wa- ter moves to E, into the canal, to occupy the low- £ est place ; and tº thus by the con- tinual rotation, W_* it passes up to " P H, O; G, F, &c. . . to D, where it is to be discharged. The machine is turned by the winch K ; the prop IR supports it, and the extreme axis is fixed in a socket P. - - ARCHITECTURE, the art of Building, has from the earliest periods of society been cultivated by mankind; and the origin of all buildings may be deduced from the construction of the meanest huts. These were, at first, made, as fig. 86, in a comi- cal figure, which is the simplest in structure, but being incon- venient on account of its inclined sides, both the figure and construction of the huts were changed, by giving them the form of a cube. Mankind at length improved in the art of building, and invented methods of rendering their habitations durable and conve- nient. The trunks of trees, deprived of their bark and other inequalities of surface, were raised above the humid soil by means of stones, and covered each with a flat stone or slate, as fig. 87, to exclude the rain; and the insterstices between the ends of the joints were closed with wax or clay. The roof Pre-cer-Szösisc was altered, and - * elevated in the >{CXC S. | centre by raft- 3. j| | Fig.87 ers, to support & - || || the materials of KXOXO. * & & A. |#| ||_ the covering,and s=: -||\º || ||º to carry of the == !--- ill ..! , LA cº, water. When ca— ===TT the rude builder ź -->– erected more stately edifices, he imitated those parts which, from necessity, had composed the primitive huts. The upright trees, with * * • stones at each end, became the origin of co- lumns,bases,and capitals; and the beams,ioists,and rafters, as fig.88, which formed the covering, gave rise to archl- - traves, friezes, and cornices. The Greeks, whose genius prompted them to combine elegance and convenience, derived their ideas of build- ing from the Egyptians. But the mind of man is influenced by the government under which he lives; the Greeks, with their independence, lost the ascendency in works of genius, and '{' + ſ.ſ. …….…………… ……………£ £§§ës Ź№ №ſ：75;§|- …---------：Źź|---~~~~）-±S！！！S= |-- -==~：=≡ºa：№S=№ ---- |-|- ,，，ſae… .|×， ，%，， ！„º "1"： { { | \{ { |× Hiſ A. H. A {{{''{{ of Published by Henry Fisher, Caxton,London, |-|---- %！« ſ'{' + 1826. |- /%， zzzzz） '{' $ in {{{} \， +\, . -o-º-º-º: wº U ºutlºo - ºsed --- lºtº ºv - zºº ºr s s s is ºss º - sº s - §§§ º S. S. s. s. s. s. 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Vitru- vius, the learned. Roman: architect, had Julius: Caesarº and Augustus for his patrons, and though employed in few works of magnificence, his rules for architecture were highly-esteemed by the ancients, and are still a standard among the moderns. The Romans. carried to the highest perfection the five orders of: architecture: the Tuscan, the Doric, the Ionic, the Corinthian, and the Composite; and though the moderns have materially improved the general structure of buildings, nothing has been added to the beauty and symmetry of these columns. To give an idea of the Orders, it must be observed, that the whole of each is divided into two parts at least; the column and entablature : and of four parts at most, when there is a pedestal under the column, and an acroter at, or little pedestal, surrounded by; the entablature: that the column has three parts; the base, the shaft, and the capital; the entablature has three likewise, the architraves, the frieze, and the cornice. Orders of Architecture. (See Plates I. II. III.)—The Tuscan Order has itsname and origin in Tuscany, first inhabited by a co- lony from Lydia, whence it is likely the orderis but the simplified Doric. On account of its strong and massive proportions, it is cal- led the Rustic order, and is chiefly used in edifices of that charac- ter-composed of a few parts, devoid of ornament, and capable of supporting the heaviest weights. The Tuscan order will always live where strength and solidity are required. The Etruscan architecture is nearly allied to the Grecian, but possesses: an inferior degree of elegance. The Trajan column at Rome, of this order, is less remarkable for the beauty of its propor- tions, than for the admirable pillar with which it is decorated. Its column is seven diameters high ; and its capital, base, and entablature, have but few mouldings or ornaments. All its parts are defined in the Plate, fig. 89; and fig. 90 represents the order complete.—The Doric Order, so called from Dorus, who built a magnificent temple in the city of Argos, and dedicated it to Juno, is grave, robust, and of masculine appearance, whence it is figuratively termed the Herculean order. The Doric possesses nearly the same character for strength as the Tuscan, but it is enlivened with ornaments in the frieze and capital. In various ancient remains of this order, the propor- tions of the columns are different. Ion, who built a temple to Apollo in Asia, taking his idea from the structure of man, gave six times the diameter of the base for the height of the column. Of this order is the temple of Thesus at Athens, built ten years after the battle of Marathon, and at this day almost entire. This order has no ornament on its base, or in its capital; its height is eight diameters; its frieze is divided into triglyphs and metopes. See the Plate, fig. 91, where all the parts of the order are accurately defined ; also fig. 92, which gives it com- plete.—The Ionic Order derived its origin from the people of Ionia. The column is more slender than the Doric, but more graceful. Its ornaments are elegant, and in a style between the richness of the Corinthian and the plainness of the Tuscan ; simple, graceful, and majestic; whence it has been compared to a female rather decently than richly decorated. When Her- mogenes built the temple of Bacchus, at Teos, he rejected the Doric after the marbles had been prepared, and in its stead adopted the Ionic. The temples of Diana at Ephesus, of Apollo at Miletus, and of the Delphic oracle, were of this order. Michael Angelo, contrary to all other authors, gives the Ionic a single row of leaves at the bottom of the capital. See the Plate, fig. 93, for all the parts of the order, and fig. 94, for the finished Ionic.—The Corinthian, the finest of all the orders, and as first used at Corinth, is expressive of delicacy, tenderness, and beauty. The capital, so rich and graceful, was suggested to Callimachus by an acanthus entwining its leaves around a votive basket that adorned the grave of an illustrious young lady. This order marks an age of luxury ; and the introduc- tion of groups of figures into the frieze of the entablature, shews that pomp and splendour had become predominant passions, but had not yet extinguished a taste for the sublime and beau- tiful. The double rows of leaves, and eight volutes sustaining the abacus, and modillions in its cornice, are all very fine. The column is 10 diameters high. See Plate, fig. 95, for all the parts; fig. 96, for the entire Corinthian order.—The Composite Order, invented, it is said, by the Romans, partakes of the Ionic and Corinthian orders, but principally of the latter. Its column is 10 diameters: high; and its cornice, has denticles, or simple modillions. . The Plate exhibits all the parts in fig. 97; and in fig. 98, the order complete. . n Saracenic, or Gothic architecture; had numerous; and promi- nent buttresses; lofty spires and pinnacles, large, and ramified windows, , ornamental niches and canopies, with sculptured Saints and angels, delicate lace-work, fretted; roofs; and san indiscriminate profusion of ornaments. The fretwork is so called from the Saxon word frattan, signifying fishes' teeth. But its most distinguishing characters are small clustered pil- lars and pointed - Fig. 99. arches,formed by the segments of two intersecting circles. This style was of Arabian origin, introduc- edinto Europe by º the Crusaders; or § 1.4% those who made | pilgrimages into -- • * * - the Holy Land. ſ ſiſ i In the reign of |-l l Henry III. many ####### ..of the old build- ings were pulled. down to , give place to new ones on this model. The cathedral of Salisbury was begun early in this reign, and finished in 1258. It is one of the finest productions, of ancient architecture in this island, and is completely and truly Gothic. This term, however, is used by the ignorant, to designate the barbarous compounds, we some- times see set up in imitation of the true Gothic. The Saxon architecture, of which we have some remains, was the Roman architecture in a decayed state. The style of building practised throughout Europe was of this kind, and so continued to be used by the Normans, with some trifling altera- tions, till the introduction of the Saracenic architecture about ‘the reign of Henry II. The characteristics are, the semicireu- lar arch, and short, thick, massive columns. It has no pinna- cles or pointed ornaments, no delineations of arms, nor statues, except in relief. The best specimen of this style is the north transept of Winchester cathedral. The Norman architecture differs from the Saxon chiefly in its increased proportion, and in the magnitude and massiveness of its buildings, arches highly ornamented with figures of angels, fruit, animals, &c.— subjects serious and ludicrous promiscuously blended together; walls without buttresses, arches supported by solid, clumsy pillars, with a regular base and capital; the capitals adorned with carvings of foliage and animals; the columns with small half columns joined to them, the surfaces ornamented with spirals, squares, network, and figures in relievo. These may be seen in the monastery of Lindisfarn in Holy Island, the |^! iſ [] bj6 A R C A R C DICTIONARY OF MECHANICAL science. cathedral at Durham, the ruined choir at Orford in Suffolk, and in the crypt or under-croft of Canterbury cathedral. The Florid Gothic, fig. 101, was admirably adapted for decorative sculptured monuments, screens, altar-pieces, elabo- rate canopies, ornamental pinnacles, octagonal niches and stalls, with the crocket ornament stealing up the angle, the pyramidal point, crowned with a large flower or a pineapple. Gothic Arch, from Four Centers. Common Gothic Arch. Method of Describing a Gothic Arch. Fig.102. v. . 7 wº F r & .** * * * * * | The arch, as it was described from two points, fig. 102, or from four points, figs. 102 and 103, possessed much grace for pen- dant decorations of fruits, ſlowers, and emblazonry. Moreover, sculptures of small imageries in the fretted roofs, characterized this style. The 13th century was the grand era of Gothic luxury, when, and in the suc- ceeding century, were erected the nave and west front of York cathedral, Litchfield cathe- dral, St. Stephen's chapel, Westminster, §. the House of Commons,) Merton and New College, Oxford. Painted and stained glass I now added much to the magnificence of the Fig.10. Gothic windows in those sublime structures. At the western painted window in the church of Batalha, in Portugal, the fathers usually assemble in the choir to chant the evening service, whilst the myriads of variegated rays which emanate from this beautiful window, resemble so many beams of glory playing around them. But the use of glass is of early origin in churches, for the monastery of Wearmouth was glazed in 647; and the windows of York and Canterbury cathedrals, so celebrated for their magnificence, are of early date. During the 13th and 14th centuries, most of the exteriors of our Saxon and Norman churches, as fig. 105, were trans- formed into the Gothic, which completed the victory of this over Sazon Architecture—Fig. 105." * º *s s = • * | every other style in the kingdom. From the end of the 14th century, no remarkable variation can be discovered. Gothic architecture, at this period, had been at its height for nearly two centuries. When Henry VIII. began the Reformation, and the dissolution of monasteries took place, the two universities were at first included in the general ruin ; these edifices, however, sacred to science as well as to religion, were saved from that dilapidation which many of the monasteries and cathedrals experienced. The desolating hands of those reform- ers who succeeded Henry VIII. destroyed many of the most beautiful specimens of this style of architecture, and despoiled them of their most beautiful ornaments. Castellated Gothic was generally used in , that age, when the feudal system rem- dered it necessary that noblemen should possess fortified castles. This style resembles the original Saxon and Norman, architecture. * - Modern Architecture.—Gothic architecture began to decline from the time of Henry VIII. A style, in which the Grecian and Gothic were mixed together, then prevailed ; but in the 16th and 17th centuries the chaste architecture of the Greeks and Romans was revived. The first improvements took place in Italy, whence they passed into other parts of Europe; and though the Italians were long accounted the first architects, England produced Inigo Jones and Sir Christopher Wren, who hold the most exalted station. The banqueting-house at Whitehall, queen Catherine's chapel at St. James’; the piazza of Covent Garden, and many other public buildings, are monu- ments of the taste and skill of Inigo Jones. The churches, royal courts, stately halls, magazines, palaces, and public structures, designed by Sir Christopher Wren, are proud tro- phies of British talent. If the whole art of building were lost, it might be again recovered in the cathedral of St. Paul, and in that grand historical pillar, called the Monument. To these, we superadd Greenwich Hospital, Chelsea Hospital, the Theatre at Oxford, Trinity College Library, and Emanuel College, Cambridge; the churches of St. Stephen in Wallbrook, St. Mary-le-bow, and fifty-two others in London, serve to immorta- lize his memory. While we contemplate these, and many other public edifices erected and repaired under his direction, we are at a loss which most to admire—the fertile ingenuity, or the persevering industry, of the artist. The architectural history of the 18th century differs from that of preceding ages in two essential circumstances. The public buildings erected during this period are, in general, not so grand and massive as those of some former periods. But while they fall short of splendour and magnificence, they are superior to most ancient structures in simplicity, convenience, neatness, and elegance. Private dwellings have been made more spacious, convenient, and agreeable to a correct taste, than in any preceding period. The liberal use of glass, in modern buildings, contributes greatly to their beauty and comfort, and is a point in which the ancients were totally deficient. In descending to the various minute details of human dwellings, especially those which have reference to elegance and enjoyment, it is obvious the artists of the 18th century exceeded all others. During the reign of his present gracious Majesty, the artificer and architect have had the fullest scope for the exercise of their respective talents, whether we consider the vast number of new churches and chapels that have been erected, and that are still building; or Stepney New Church.—Fig. 106. º E - i - | ŽSR, YXC * * SY i #! ; & #| || _J. T. w = HT ==A- *m. *Sºrsº - * -** --- the extensive improvements which the metropolis has under- gone. But all these are outdone by the buildings in the New :* A R C A R I 57 DHCTIONARY OF MECHANICAL SCIENCE, Town of Edinburgh, and ia Glasgow, where; the whole of the very magnificent and classical edifices that have been reared, are constructed of durable free-stone, and decorated in a style that does equal hanour to the genius of the people, and the spirit of the age. It would be impossible in this work to ehu- | merate and describe the new churches which have been built since the year 1818. We may, however, give as a specimen Stepney New Church, fig. 106, which will hold 1500 persons, two-thirds being in free sittings. Architectural Ornaments.-Balusters are pillars of wood, stone, and used to ornament the tops of buildings, and to Sup- port railing; when continued, they form a balustrade: Cary- atides, figures of women dressed in long robes after the Asiatic manner, to support entablatures in buildings. Other female figures have been used for a similar purpose, but the original name is still retained. A war had been carried on by the Athenians against the Carians; the latter were totally van- quished, their wives were made captives, and to commemorate this event, trophies were made by the Athenians, in which figures of women, habited in the Cryatic manner, were used for the purpose just explained, and this is in fact the origin of this part of architecture. Persians, so called from a victory gained over the Persians by Pausanias, who having brought home prisoners, spoils, and trophies to the Athenians, they chose Persian male figures to support the entablatures which have been changed in the same manner as the Caryatides. Persians may be of another size; the larger, the greater the effect which they impress on the spectator's mind. In arsenals, galleries of armour, &c. they are advantageously used. Pilasters have their bases, capitals, and entablatures, the same as those of columns but are square, not round as columns are. A Portico is a range of columns covered at the top ; that of Palmyra was 4000 feet long. Termini, figures anciently used to mark the limits of possessions, are still used in the human shape as ornaments for temples and garden edifices. There are many other architectural terms, which will be found described under their respective names. . See the annexed Plate. In the practice of Architecture, every gentleman is guided by circumstances; but the choice of situation seems to be dictated, in most cases, by the nature of things. A farmer ought to dwell in the centre of his farm ; a man of fortune builds for health, neighbourhood, prospect, situation, &c. As regards the construction of edifices, the distribution of apartments, &c. the rules and plans that might be given would fill many volumes; and Aquatic Buildings, Bridges, Harbours, Roofs, Arches, &c. are all described and illustrated under their respective titles, in the work. - - - ARCHITRAVE, that part of a column which lies imme- diately upon the capital, being the lowest member of the entabla- ture ; and the - ARCHIVAULT, is the interior contour of an arch or band, adorned with mouldings, running over the faces of the arch stones, and bearing upon the imposts. ARCHIVE, a chamber in which records are kept, as the Rolls' Office, in which the archives of the Court of Chancery are kept. - ARCHYTAS, a Pythagorean philosopher, and distinguished mathematician, of Tarentum, who flourished about 400 years before Christ, and to, whom Aristotle is said to have been indebted for his ethical principles and maxims. To the inge- nuity of Archytas, as a mathematician, we owe the method of finding two mean proportionals, mechanically, between two given lines, with a view to the duplication of the cube ; and we derive from his skill in mechanics, the invention of the screw, crane, and various hydraulic machines; flying pigeon, or winged automaton. The astronomical and geographical knowledge of Archytas is celebrated by Horace in a beautiful ode, recording also his death, which was occasioned by a shipwreck :— “Archytas, what avails thy nice survey Of ocean's countless sands, of earth and sea? In vain thy mighty spirit once could soar To orbs celestial, and their course explore; If here, upon the tempest-beaten strand, You lie, confin'd, till some more lib’ral hand Shall strew the pious dustin funeral rite, • And wing thee to the boundless: realms of light.” ARCTIC, the North Pole, because the last star in the tail of the Little Bear is near the pole of the world. ARCTIc Circle, a lesser circle of the sphere 234° from the north pole. ARCTIUM, burdock. • ARCTURUS, astar'of the first magnitude in the constellation Arctophylax, or Boötes; see Job ix. 9. xxxviii. 32. This star is supposed to be nearer our earth than any other in the northern hemisphere. AREA, any plane surface on which we walk, &c. or the site on which any building stands, or 10 20 º L( e * * the superficial contents of any figure. Fig.1/07. Thus, if a field be 40 feet on each D}. +. side, the contents will be 40 × 40 = 1600; or it contains 1600 little | squares, each one foot, one inch, &c. every way. In fig. 107, each little D contains 10 feet, therefore the 16 30 squares contain 1600 feet. ARECA, faufel nut. AREOLA, the colour surrounding - the nipple of the breast. AREOPAGUS, rock of Mars, a sovereign tribunal at Athens, famous for its justice and impartiality. ARETHUSA, a marsh plant, that requires to be kept moist in two-thirds peat and one-third loam. ARGOPHYLLUM, white leaf. ARGO NAVIS, the ship Argo, a southern constellation, and type of the vessel in which Jason sailed from Thessaly to Colchis. On the east coast of the Black sea, to recover the golden fleece. More properly, this ship is a type of the ark of Noah. The constellation Argo Navis is bounded on the north by Mono- L0 ceros and Pyxis Nautica, anciently of course by the Water Snake and the Little Dog; east by Robur Caroli, anciently by the Centaur; south by Piscis. Volans and Equuleus Pictorius; and west by Canis Major and Columba Noachi. There are sixty-four stars in Argo, reckoning by the Britannic Catalogue, viz. one of the 1st magnitude, six of the second, nine of the 3d, nine of the fourth, &c. Thé brilliant Canopus, situated near the keel, has 52° 36' south declimation, and its right ascension in time is 6 ho. 20' 1", or 95° 15', and though invisible in our northern latitude, it culminates as follows:— MONTH. CU L.M. MONTH. CULM. MonTH. CULM. ho. mi. ho. mi. - ho, ini. Jan. 11 31 A. May 3 47 A. Sept, 7 36 M. Feb. 9 24 A. June 1 44 A. Oct. 5 27 M. March || 7 31 A. July II 36 M. Nov. 3 22 M. April 5 37 A. Aug. 9 32 M. Dec. 1 49 M. A small part of the Ship’s poop only appears above the hori- zon of Britain, and it is superfluous therefore to trace any com- binations among the stars of this constellation. ARGUMENT, in Astronomy, is in general a quantity upon which another quantity or equation depends, or some circum- stance relating to the motion of a planet; or it is an arch, whereby we seek another unknown arch, bearing some propor- tion to the first: hence, ARGUMENT of Inclination, or Argument of Latitude, of any planet, is an arch of a planet's orbit, intercepted between the ascending node and the place of the planet from the sun, num- bered according to the succession of the signs. Annual ARGUMENT of the Moon's Apogee, or simply Annual Argument, is the distance of the sun's place from the place of the moon's apogee ; that is, the arc of the ecliptic comprised between those two places. - + ARGUMENT of the Parallaa, denotes the effect it produces on an observation, and which serves for determining the true quantity of the horizontal parallax. - ARGUMENT of the Equation of the Centre, is the anomaly, or distance, from the apogee or aphelion ; because this equation is calculated in an elliptic. orbit for every degree of anomaly, and varies according to the variation of the anomaly. ARIES, op, the Ram, or Lamb, the first of the zodiacal signs; agreeably to the fixed zodiac of Hipparchus; when the sun enters Aries on the 20th of March, and the vernal equinox begins. From this point we reckon the right ascension of the stars, and the longitudes of the celestial bodies. The fact is, Q § 5S A R I A R T DICTION ARY OF MECHANICAL SCIENCE. the earth is at this season of the year in Libra, and the sun, as seen from the earth, appears in Aries. The boundaries and contents of this constellation are, north by Triangula and Musca, east by Taurus, south by Cetus, and west by Pisces. This sign contains 66 stars, viz. one of the 2d magnitude, one of the 3d, two of the fourth, &c. The chief star in Aries, called a Arietis, is situated in his forehead. Its declination is 22° 36' 30", and its right ascension 29° 15' 30". N. E. 4 E. point of the compass, at London, and culminates on the first day Óf each month, as in the following Table: Meri- dian Altitude, 6° 5' 30". - Month. Rises. CULM. I. MonTh. Rises. CULM. ho. mi. ho. mi. ho. mi. ho. mi. Jan. | 11 0 M. 7 15 A. July 10 50 A. | 7 5 M. F6b. 8 37 M. 5 0 A. Aug. 9 0 A. | 5 5 M. Mar. 6 45 M. 3 15 A. Sept. 7 0 A. | 3 8 M. April 4 56 M. 1 15 A. Oct. 5 15 A. | 1 18 M. May 3 0 M. 11 30 M. Nov. 3 20 A. | 1 30 A. June 1 .0 M. 9 30 M. Dec. 1 15 A. | 9 30 A. ARISTAEUS, an eminent geometrician of Crotonia, who lived 330 years before Christ; and was author of five books on the Conic Sections, which, however, have never been transmit- ted down to us, though those of his contemporary Menechmus, have been preserved. ARISTARCHUS, a celebrated Greek astronomer and phi- Iosopher, born at Samos, flourished about the middle of the third century before Christ. Aristarchus is well known to have maintained the modern opinion with regard to the motion of the earth round the sun, and its revolution about its own centre or axis. He also taught, that the annual orbit of the earth is but merely as a point, compared with the distance of the fixed stars. He determined the distance of the sun from the earth, and concluded, that it contained at least 18 or 20 times that of the moon from the earth. Aristarchus likewise found, that the diameter of the moon bears a greater proportion to that of the earth, than that of 43 to 108, but less than that of 19 to 60; so that the diameter of the moon, according to his statement, should be somewhat less than a third part of the earth. He also estimated the apparent diameter of the sun at the 720th part of the zodiac. Besides his astronomical discoveries, Aristarchus invented a peculiar kind of hemispherical sundial. The only work of this ancient astronomer now extant, is a treatise “ on the 'Magnitude and Distances of the Sun and Moon,” published by Wallis, with his own notes, and Com- mandine’s version at Oxford, in 1683, 8vo. ARISTOLOCHIA, birthwort. ARISTOTELIAN, any thing relating to the doctrines or philosophy of Aristotle. - ºf ARistoteli AN Philosophy, the philosophy taught by Aristotle, and maintained by his followers. It is otherwise called the Peripatetic Philosophy, from their practice of teaching while they were walking. The principles of Aristotle’s philosophy are: Instead of the more ancient systems, he introduced matter, form, and privation, as the principles of all things; but it does not appear that he derived much benefit from them in natural philosophy. His doctrines are for the most part so obscurely expressed, that it has not been yet satisfactorily ascertained what his sentiments were on some of the most important subjects. He attempted to confute the Pythagorean doctrine, concerning the two-fold motion of the earth; and pre- tended to demonstrate, that the matter of the heavens is unge- nerated, incorruptible, and not subject to any alteration; and he supposed that the stars were carried round the earth in solid orbs. - - ARITHMETIC, the science of numbers, whose several rules of Addition, Subtraction, &c. will be found under their respec- tive heads. The marked superiority, indeed, of our present numeral system over that of the ancients, is so conspicuous, that since the time of its first introduction into Europe, nearly all knowledge of the more imperfect and obscure methods before used is obliterated and forgotten; and even the slight vestiges of these abandoned monuments, which now remain, have become so rare and difficult to be traced, either in the original works, in which they might be expected to be found, or in the commentaries and translations of later writers, that except from the scanty relation that has been given of them by It rises on the the government vessels. Wallis, and the more recent and ample detail of Delambre, but little further information can be expected on the subject; particularly as it is now well known, that the authors of most of the early performances in which these methods were em- ployed, have contented themselves with barely giving the results of calculations, without shewing the nature of the process, or the different steps of the operation. ARK, a floating vessel built by Noah, about which, all beyond the account of scripture, is mere conjecture, and had much better be omitted in this work. The truth, as related under the unerring direction of the divine Spirit, is found in Genesis. ARK of the Covenant, a chest in which the Israelites kept the golden pot that contained the manna, Aaron's rod, and the tables of the covenant. * . 2 . ARMED, a cross-bar is said, by sailors, to be armed, when Some rope yarn, or the like, is rolled about the end of the iron bar, which runs through the shot. In Heraldry, the horns, feet, beak, and talons of birds of prey, are armed, when of a diffe- rent colour from the body. ... An armed ship is, properly, one of See Ship of WAR. ARMIGER, a title of dignity to such gentlemen as are entitled to bear arms by courtesy or creation. • ARMILLARY SPHERe, an artificial sphere composed of various brass circles, to illustrate the imaginary lines with which the earth is supposed to be surrounded. ARMOUR, a defensive dress, worn to secure the body in battle, &c.; armour cap-a-pée consisted of a casque or helm, gorget, cuirass, gauntlets, tasses, brassets, cuishes, and covers for the legs, to which the spurs were fastened. Lastly, the horses even had their armour to cover the head and neck. ARMOURY, a storehouse for arms; as the Tower, the arsenal of Woolwich, &c. In Heraldry, arms are marks of dignity and honour, and are, like titles, hereditary; expressing, on the field of the escutcheon, the degree, merit, and quality of the original bearers. The ancient armour was tried and proved by raising it to a sufficient height, and then letting it fall on a large stone or pavement: if it was not injured by fracture, it was good. ARMY, a large number of soldiers, consisting of horse and foot completely armed, and provided with artillery, anmuni- tion, provisions, &c. under the command of one general-officer, having under him a general of horse and one of foot, a major- general for every two brigades, and nearly half as many lieutenants-general. : ARNICA, leopard’s bane. - AROMATIC VINEGAR, an acetic solution of camphor, oil of cloves, oil of lavender, and oil of rosemary; take a sufficient quantity of each to make it pleasant, and mix them together. . ARPENT, a measure of an 100 perches square. ARRAIGNMENT, in Law, to call a person to answer in form of law upon an indictment; and the ARRAY is the ranking or setting forth of a jury, or inquest of men impannelled on a cause. An ARRest, is the restraint or beginning of imprison- ment of one’s person, by a lawful warrant, and is either civil or criminal. When any one is arrested for a criminal offence, the officer who arrests him is bound, (by the habeas corpus act,) under heavy penalties, to deliver to the prisoner, or his agent, within six hours after demand, a copy of the warrant of com- mitment, in order that no one may be imprisoned from malice or revenge, or without knowledge of the charge against him. In case such copy is denied, on complaint in writing on oath, the lord-chancellor, or any of the twelve judges, provided it is a bailable offence,—or on affidavit, that a copy is denied,—can award a writ of habeas corpus for such prisoner to be brought immediately before him; and he is obliged to discharge the party, on receiving bail. See Assize. - - ARRESTS, in Farriery, mangy tumors upon a horse's hinder legs, between the ham and the pastern. ARRONDEE, in Heraldry, the curved cross, whose arms terminate in the edge of the escutcheon. - ARSENAL, a royal or public magazine, for the making or keeping of arms, naval or military furniture and equipments, \ &c., as the arsenal of Woolwich, of Toulon, &c. ARSON, the malicious burning of a house, &c. of anothel man, which is felony at common law. . ART, the application of knowledge to practice ; hence w have the terms useful or mechanic, liberal or polite arts; the wzºrºwozºwozºwevær， ºcaerºzawºrzºn， 5 _…_---- - - - - - ---- ·ſaetºt o·lae|-…，|- |-ſºſ|-||\， ….………|~~~~ ----/**·| （~~~~，| - |- ·r·º·：· AV |- …ſae·|×…………：|-|- |- |-*ſ'）; ----·！----|- |-|-|-·s………….…… |,，tºº.|× |-， _…：，xº·|ſaeº.ſz00| |-|----！**）, º---- - |-----ºAY----ſaeſºrº ºf| *º-- ºu， ||-| ， ! -|-，·77，*********4.1+…+w - …， w|-| |-ſº： ，|-|（1* |-¿|||****� ſae|--，-|- ſae…….… ||-| z| _--------···---···77 -*ºv， ~- ---- ~ E- |- |- |- |-ſae， ºr.…….……！”…”|- - 1 % . . ************] ©as ---- --***·：-） -----| __，_，_|\ ]）（^* ººººº ）|- ···|-- …'！）?（?：'，· ）.|-|-|-！！！！！！！!%º-ſae | ----： , _ »…º…”…………………-----L-， ----|-- |-……………….………… Źsašºſ ·· -----|- ----„，a xoºrº·Å* |----－· ·praevae |-ſºr， wº· ſae 。」 - wae”· ſº ſaeg”. • |- mae’’， |- *№.ſºſ |× ，ſºº，）！«， |×-|-_-'！！！ ！”---- ，，…， ……. **…t º lae vºor：ba| **I union South Lat. I "… … * * * * * * *r', - |- |- ſae.- _ |-*:）----|-_ 1"ºººººs！--e^^***---- ---- · ---- ---- ：：：- % · “…|- |- ·ºz， ~|- | _ A R U DICTIONARY OF MECHANICAL scIENCE. A S I - 59. former requiring manual labour principally, the latter requiring the exercise of mind more than of the hand and body. . ARTEMISIA, mugwort. from the heart to all parts of the body. See ANA to MY. - ARTICHOKE, a well-known plant, grown chiefly for culinary uses, and eaten with melted butter and pepper, either plain, boiled, or stewed, and added to ragouts, and highly seasoned dishes. . The leaves and stalks contain a bitter juice, which, melted with an equal portion of white wine, has been success- fully employed in the cure of dropsy, when other remedies have failed. • , & - - . ARTICLES of FAITH, doctrines of Christianity, allowed and established by the church for our belief. The thirty-nine articles were confirmed by royal authority in 1652. The law requires a subscription to these articles, of all persons ordained to be deacons or priests; of all clergymen inducted to any ecclesiastical living ; of licensed lecturers and curates; of the heads of colleges, chancellors, officials, commissaries, and schoolmasters. Dissenting teachers are to subscribe all, except the 34th, 35th, and 36th, and part of the 20th, (and in the case of Anabaptists, except also part of the 27th,) otherwise they are exempted from the benefits of the Act of Toleration, 13 Eliz. cap. 12, 13, 14. Chas. II. cap. 4. 1 Will. III. cap. 12. ARTIFICER, a manufacturer of any commodity, as a smith, carpenter, &c. personal services, and incorporated into companies, enjoying their, peculiar temples and tutelar gods; but still they were treated with contempt, most of them being slaves and foreign- ers, whose poverty exempted them from taxes, and whose equivocal character rendered their names unfit for the censors’ books, and their persons for war. How much the state of the artificer is bettered since Rome gave law to the world, the prosperity, liberty, and opulence of Great Britain sufficiently prove. Still by the English laws, artificers in wood, iron, steel, brass, or other metal, are prevented, by statute, from quitting the kingdom. And such as go abroad, and do not return on warning given by our ambassadors, shall be disabled from holding lands by descent and demise, and from receiving any legacy, &c. and be deemed aliens. A heavy penalty is also inflicted on persons seducing artificers to go abroad. Statutes, 5 Geo. I. cap. 27; 23 Geo. II. cap. 13. § 1. . . ARTILLERY, the science which the officers of artillery ought to possess; or the soldiers destined for the service of guns, cannon, mortars, &c., The artillery of Britain consists of both horse and foot soldiers, whose chief rendezvous is at Woolwich. - :- ARTILLERY Park, the place in the rear of both lines of an army for encamping the artillery, which is drawn up in lines, of which one is formed by the guns; the ammunition waggons make two or three lines sixty paces behind the guns, and thirty distant from one another: the pontoons and tumbrils make the last line. The whole is surrounded by a rope fastened to stakes, defining the camp ground; and the gunners and matrosses encamp on the flanks; and the bombardiers, pontoon men, and artificers, in the rear. - ARTOCARPUS, the bread-fruit tree, grows wild in Ota- heite, and other islands of the South Seas. It is about 40 feet in height, with large spreading branches, and bright green leaves, divided into seven or nine pea-shaped lobes, and loaded with large globular berries about the size of a child’s head; it affords a good mourishment, and from its inner bark there are separated fine white fibres, which are woven into cloth. . . ARUM, wake-robin, or cuckow pint. . - ARUNDELIAN MARBLEs, are ancient stones, on which is inscribed a chronicle of Athens, engraved in Paros 264 years before Christ; and they take their present name from Thomas earl of Arundel, who procured them from the East, and made a present of them to the University of Oxford. This chronicle begins 1582 years before Christ; but it is so defaced, that the sense is discovered chiefly by conjectures. But in a dissertation, entitled, “The Parian Chronicle,” the authenticity of these marbles has been questioned: 1st. Their characters have no certain or unequivocal marks of antiquity; 2d. it is not pro- bable, that the chronicle was graven for private use; 3d. nor by public authority; 4th. it is not once mentioned by any The artificers of Rome were exempt from all | cape of Malacca. writers of antiquity; 5th. some of the facts in the chronicle. seem to have been taken from the writers of a later date ; 6th:. º Parachronisms appear in some of the epochas; 7th. the history. ARTERY, a conical tube, or canal, which conveys the blood | of their discovery is obscure and unsatisfactory. These marbles. had been totally unknown or unnoticed for almost 1200 years, and at last are dug out of the ground—nobody can tell us when, or where ! - - ASBESTOS, a native fossil stone, which may be split into threads and filaments from one to ten inches in length, very fine, brittle, yet somewhat flexible, silky, and of a grayish colour. Asbestos is insoluble in water, and possesses the wonderful property of being incombustible. - ASCENDING STARs, are such as are rising above the horizon of any given parallel of the equator. .. . AscenDING Node, Sl., that point of a planet's orbit where it passes the ecliptic, to proceed northward. . , , Ascension, Right, of any of the heavenly bodies, is that degree of the equinoctial counted from the beginning of Aries, which rises with the sun or star, in a right sphere. Oblique Ascension; an arc of the equator, intercepted between the first point of Aries and that point of the equator which rises toge- ther with a star in an oblique sphere; and the ascensional difference is the difference between the right and oblique ascension. - - • - - ASCITES, dropsy of the abdomen. ASCLEPIAS, swallow-wort. . . ASCYRUM, Peter's wort. - - - - ASHES, the earthy particles of combustible substances after they have been burned; those of vegetable bodies possess- ing a fixed salt, as potash, pearlash. Ashes are an excellent manure for cold and wet grounds. In their religious, ceremo- nies, the Jews sat on ashes, threw ashes on their heads, and fed on ashes, which, however, is a poetical allusion. There was, nevertheless, a lustral water made with the ashes of a sacrificed . heifer, which was distributed to the people, and used in purifi- cations as often as they touched a dead body, or were present at funerals. Numb. xix. 17. 2 Sam. xiii. 9. and Ps. cii. 9. - ASIA, extends about 6500 geographical miles east and west, reckoning from the Hellespont to what is called East Cape; and about 4500 geographical miles, north and south, from Cape Cevero Vostochnoi, on the Arctic ocean, to the southern And it contains the following states:—In the North. The countries of Siberia, or Russian Tartary; whose chief towns are, Astracan, on the Wolga, Tobolsk, on the Irtish. . In the Middle. Countries: the Chinese empire, Chinese Tartary, Tibet, Independent Tartary, Turkey in Asia. Chief towns: Pekin, Cashgar, Lassa, Samarcand, on the Sogda, Aleppo, and Jerusalem. In the South. Countries; Arabia, Persia, Hindostan, the Birman empire, Malaya, or Malacca. Chief towns: Mecca and Medina, Ispahan and Shiraz, Delhi and Calcutta, Ummerapoora and Ava, Malacca. The religions of Asia are very various: in Turkey the Mahom- medan and Christian both prevail; in Asiatic Russia are found the two former, and also a species of Hindooism; the Chinese believe in polytheism; in Tibet, the religion bears a close affinity to that of the Hindoos : in Japan, polytheism obtains ; the Birmans are worshippers of Brahma, as are also the Sia- mese, and the Hindostanese; the religion of Persia is the Mahommedan, as is also that of Arabia, while in the Asiatic islands several of the foregoing faiths have their respective devotees ; and there are some insulated savages without any vestige of religious rites. The oceans, seas, bays, and gulfs, belonging to Asia, are: the Arctic, Pacific, and the Indian oceans; the Arabian Gulf, or Red Sea, between Africa and Arabia; the Persian Gulf, between Arabia and Persia, receiv- ing the Euphrates and the Tigris; the Bay of Bengal, sepa- rating the peninsulas of India; the Gulfs of Siam and º ; the Yellow Sea, the sea of Japan, and that of Okhotsk. Adja- cent to Europe, Asia claims a share in the Levant, the Archi- pelago, the sea of Marmora, the Black Sea, and the sea of Azof. The Caspian Sea is an inland lake, 700 miles long, and from 200 to 700 broad. The sea of Aral is 200 miles long, and 70 broad; and that of Baikal is 850 miles in length, but only 35 in breadth. The chief Asiatic straits are those of Babel- mandel, Malacca, Sunda, Corea, and Bherrings, between Asia and America. The mountains are, the Ouralian chain, forming 60 A S I A S i ' DICTIONARY OF MECHANICAL SCIENCE. the boundary between Europe and Asia; the Altaian chain, extending 6000 miles across the centre of Asia; the mountains of Tibet, the highest on the globe, being in one place above | 26,000 feet above the level of the sea; Mount Taurus; the Caucasian chain, Mount-Ararat, Lebanon, and the Gauts of Hindostan. The chief rivers are the Obe, the Emissei, the Lena, the Amour, the Hoan-ho, the Kian-ku, the Maykaung, the Maygne, the Trawadely, the Burrampoot, the Ganges, the Indus, the Godavery, the Kistna, the Euphrates, the Tigris, and the Wolga. The canals of China are very numerous, , and facilitate commerce in all directions; while the magnitude of the Ganges, the Indus, and many other rivers, admits of an tuninterrupted navigation for nearly 1000 miles, for vessels of 200 tons burden. The Asiatic islands are the Laccadive and Maldive islands, Ceylon, the Nicobar and Andaman isles; the Japanese islands, the Eastern Archipelago, Austral-Asia, and Polynesia. - w Turkey in Asia.-This region is divided into nine provinces, extending from the shores of the Archipelago, in Europe, to Persia; and these provinces are subdivided into governments arbitrarily ruled by pashas, or military commanders. The provinces are, Natolia, in the west; Karoman, in the south ; and Roum, in the north-east; Guria, Mingrelia, Circassia, north of Armenia, or Turcomania, and south of it are Kurdis- tan and Irak-Arabi; Mesopotamia, and Syria. The population is estimated at ten millions, and of this mass of human beings, one half are pastoral wanderers, without industry, arts, or civilization. The chief cities are, Aleppo, with a population of 250,000 inhabitants; Damascus, containing 100,000 souls; Smyrna, 120,000; Prusa, 60,000; Angora, 80,000; Tokat, 60,000; Bassora 50,000; and Bagdat, 40,000. Aleppo is famous for its manufactures of silk and cotton ; and its numerous mosques, surmounted with white minarets, and relieved in the distant landscape by the tall cypresses, give this elegant city a most picturesque appearance. Damascus for its swordblades is unrivalled; and its manufactures of silk, cotton, and soap, are very considerable. Smyrna is the chief mart of European trade on the shores of the Levant; but the pestilence retards its prosperity. The climate is most excellent; and though the soil be in general good, agriculture in Syria is in a most wretched condition. The chief rivers are the Euphrates, the Tigris, the Kizil-Irmak, or Halys of antiquity; the Meander; . the Sarabat, or ancient Hermus; and the Orontes, in Syria. The lakes are, Van, in Kurdistan; the Dead Sea, in Syria; the Tata, or Palus Salsa, of Asia-Minor; Ulubad, in Natolia, and the Isnick. The mountains are, the Taurian Chain; the Caucasian mountains; Ararat, in the east of Armenia; Leba- non, in Syria; Olympus and Ida, on the east of the Archi- pelago. These mountains are clothed with immense forests of pine-trees, oaks, beeches, elms, and other alpine trees, which furnish safe retreats to tigers of the smaller breed, hyaenas, wild boars, troops of jackals ; and the ibex roves on the sum- mit of the Caucasus; while Angora is celebrated for its singu- lar goats and cats, from whose wool are manufactured Angora shawls, &c. The islands belonging to Asiatic Turkey are, Mytilene, Scio, Samos, Cos, and Rhodes. Mytilene is moun- tainous, but agreeably diversified with olive gardens, vine- yards, and plantations of myrtle. The climate is exquisite, and the coast is, finely indented with numerous creeks and havens. Scio, or Chios, contains about 60,000 inhabitants; and the Greeks make a decent livelihood in the cultivation of mastic gum, for the ladies of the sultan's harem. Samos, with a population of 12,000 Greeks, is famous for its pottery, its honey, and wax. Cos is covered with groves of lemon-trees. Rhodes, whose population is 30,000, was once celebrated for its colossal statue in bronze, and its having been possessed by the knights, of St. John of Jerusalem. Cyprus is fertile, but agriculture is neglected. . Its wines and oranges are excellent, and its hills are bedecked with the most beautiful flowers. Russia in Asia.-The Russian empire extends along the whole of Asia. If we compute the degree of longitude in that high, latitude at 30 miles, the length (reckoning from 37° east longitude, to 170° west longitude) will be about 4590 geogra- phical miles; and its mean breadth cannot be less than i960 miles, estimating from Cape Vostochnoi to the sea of Baikal. The ancient name of this vast empire was Siberia. The popu- : lation of this extensive empire is almost all of primitive origin, consisting of Samoides, Monguls, Kalmucks, Tartars, &c. And they profess, according to their tribes, the Mahommedan reli- gion, that of the Greek church, or the superstition of Dalai-Lama, &c. The government of Siberia is divided into two branches, that of Tobolsk in the west, and Irkutsk in the east; and the population does not exceed three millions and a half. The Tar- tars are generally hunters, or herdsmen, feeding horses, camels, oxen, sheep, and goats; and their women busy themselves in tanning leather, gardening, and providing winter provisions. The Kalmucks are divided into three classes, nobles, clergy, and people, and the power of their chief consists in the num- ber and opulence of his subjects. The Monguls are of short stature, with a flat visage, small oblique eyes, thick lips, and short chin, from which depends a scanty beard. Their hair is black, and their complexion a yellowish brown. Like all pas- toral tribes, they are docile, hospitable, and active, but volup- tuous; and hence industry is a virtue entirely confined to the females. Wandering in herds in quest of sustenance for their flocks, with much mirth they amuse themselves in horse-racing, archery, wrestling, pantomime, dancing, cards, and chess. The chief cities are, Astracan, at the mouth of the Wolga; Azof, Tobolsk, Kolyvan, on the Ob : Irkutsk, the chief mart of commerce between China and Russia. The chief manufac- tures are, leather, salt, isinglass, kaviar, (the salted roe, of a large fish,) and pitch; and the chief articles of commerce are sables, furs, hides, rhubarb, and raw silks, which are exported, or exchanged, for tea, silk, porcelain, wine, fruit, coffee, rice, woollen cloths, iron, and household goods. In so extensive a country the climate and soil are very various; though in general the former be frigid rather, than temperate, the latter might be cultivated to great advantage in the southern and western districts, were the peasantry not sold as slaves with the ground they tread on. The chief rivers are, the Ob, navigable almost to its source, and abounding in fish ; the Yenidei, issuing from the Baikal, or Holy Sea; the Selinga, flowing into the Baikal; the Lena, of great breadth, and full of islands; the Wolga, the Amur, and the Onon. The chief lakes are, those of Piazinsko, in the north; the Baikal, in the south; the lakes of Tchany and Soumi, between the Ob and Irtish ; the Bagdo, to the north of the Caspian, is salt water, as is also the Atlan-Nor, or Gold Lake. The mountains are, the Uralian chain; Bogdo-Alim, adjoining the Mongolian desert; the Altaian chain; the Schlanganberg, rich in minerals, as are also the mountains of Nenshinsk; the mountains of Ochotsk, many branches of which consist of red and green jasper; and the classical Cau- casus, whose summits are crowned with everlasting ice and snow. Asiatic Russia abounds in forests and stepps, or exten- sive level plains, which resemble the sandy bed of a sea, with scattered patches of thin grass, stunted thickets, spots of salt, and saline lakes. In the forests, the terrible urus and the bear range ; the argali, or wild sheep, and the ibex, or rock goat, inhabit the Caucasus; the rein deer performs the office of the horse; the mountains of Baikal abound in large stags; and the white foxes of the Eastern Archipelago rival the monkey in mis- chievous tricks. The isles belonging to Asiatic Russia are, the Aleutian isles on the east of Kamschatka, the Andrenovian or Fox islands on the west of the former ; and the Kurilian isles, extending from the south of Kamschatka to Japan. Several of these isles are volcanic ; and they all swarm with foxes. The Chinese Empire.—This vast empire extends in an easterly direction 4200 geographical miles, and southerly 1740 miles. By glancing at the map of Asia, we perceive it stretch- ing from the Pacific Ocean to the river Sihon, and from the Uralian mountains to the tropic of Cancer. It is divided into three parts, China Proper, the kingdom of the Mandshurs and Monguls, on the north and west, and the territory of Tibet. I. China Proper.—China Proper (extending from the great wall in the north to the Chinese sea in the south) is 1140 geo- graphical miles long; and in breadth (from the shores of the Pacific to the frontiers of Tibet) it is computed at 880 geogra- phical miles. The religion is polytheism; the government patriarchal ; hence the amazing population and general ease and happiness of the people. The population amounts to three hundred, and thirty-three millions of souls, the army is, one million, and the revenue amounts to nine millions, sterling. tº A S 1 A S 1 61 DICTIONARY OF MECHANIC A.L SCIENCE. The features of the Chinese proclaim their affinity with the Tartars, Monguls, and Mandshurs; and though they appear highly civilized, science is still in its infancy among them, and must ever be so, where, from age to age, genius is cramped by the children following the business of their fathers. The chief cities are Pekin and Nankin ; the former possessing a popula- tion of three millions of souls, and the latter is yet more exten- sive. In Canton there are a million and a half of inhabitants. The characters of the Chinese people in the different provinces are thus portrayed in the last court calendar of the celestial empire.—1. Peking, or Shun-teen-ſoo. The people are strong and brave ; silent, famous for politeness and justice ; plain, unceremonious, and moral, regenerated by their vicinity to the emperor.—Paou-ting-foo. Literati not endowed with remark- able talents, and agricultural people.—Yung-ping-foo. The lite- rativalue their reputation; a frugal people, attentive to agricul- ture.—Tee-tsin-foo. A mixed people from every part of the coun- try; gay and extravagant, some frugal.—2. Keang-see—Keang- nin-foo. An extravagant people, a greatnumber of literati.--Soo- chow. The scholars are very polite, and the people taught to love each other. Their manners are pure, and instruction has a powerful effect.—Sung-keang-foo. The literati are studious, the people eminent fºr benevolence.—3. Gan-hwuy. A light unsteady people ; economical, and of good appearance.—4. Keang-se. The literati are partial to classical learning, the peo- ple attentive to husbandry.—5. Che-keang.—Hang-chow-foo. Gems and rarities are here collected. Foreign and home trade are united. The people are genteel and elegant. The literati are very methodical.-6. Fo-kéen, Fo-chow-foo. Inwardly sincere, and of a gay exterior; very attentive to business, and value economy.—7. Hoo-pee, Woo-chang-foo. A mixture from every part of the empire. Every family obscrves its own customs. The Chinese roads are excellent, and no country excels this in inland navigation. Irrigation' is very well prac- tised, husbandry is meat and clean, and the emperor himself is not ashamed to hold the plough in its season, and sets an an- nual example of the veneration due to the chief branch of human industry. The lakes are noble and extensive, and afford vast quantities of fish, which are taken by trained birds. The rivers are the Kian-ku and the Hoan-ho. The mountains, though numerous, have not yet been accurately described; and except in the loftiest districts, cultivation has annihilated all the great forests. Yet tigers, buffaloes, wild boars, bears, rhinocerosex, cancis, and deer, find ample shelter. The common people pound their coal with water, and bake it in cakes for use. The Chinese islands are Formosa, Hainan, and the isles of Leoo-keoo, between Formosa and Japan. Their inhabitants form a civilized kingdom, subject to China, and their manners appear mild, affable, gay, and temperate. II. Chinese Tartary.—Chinese Tartary, or Mongolia, ex- tends over the vast regions between Tibet, China, and the Arc- tic Ocean ; and from the Black Sea to the north-eastern boun- daries of Asia. That is to say, from 72° to 145° east longi- tude, or seventy-three degrees, equal to 3100 geographical miles, taking the medial latitude at 45°; and from the Rus- sian confines to Tibet, its breadth of 18° will give 1,080 geo- graphical miles. The religion is called Shumanism, or the belief in a Supreme Author of nature, who governs the uni- verse by the agency of numerous inferior spirit: ; but a living Lama, or embodied spirit, is acknowledged and worshipped; and this Lama is a human being like ourselves! The princes pay homage to the Chinese empire; the population amounts to about six millions of souls; and the whole country is divided by the Chinese into the three great governments of Chinyang, Kiren-oula, and Tsitchicar ; while the territory of the Oelets or Kalmucks comprises Gete, Little Bucharia, and the countries of Turfan. The chief towns are, Cashgar, Yark- and, and Kotan, in Little Bucharia; Turfan, Hami, Chami; Coucou, Hotun, Tsitchikar, Merguen, Petouna, Kirin, and Nigouta. The chief city of Corea is Kinkatao. The chief trade of these places lies in pearls, horses, musk, and furs. Corea is celebrated for the most exquisite horses, only three feet high. A mare of this breed was exhibited in London, in 1820. The climate, in general, is as mild as that of France and Spain, and the great Table Plain, extending from 80° to 110° east longi- tude, or 1380 geographical miles, is the most singular feature. of Tibet. - of Jesso, is mountainous towards the centre, but the shores in the face of the country. In all Chinese Tartary the pre- dominating substance of soil is black sand, and agriculture is wholly neglected. The chief rivers are, the Amur or Saga- lian-Oula ; the Yarkand, and the Ili; the former falling into the lake of Lop, the latter into that of Balkash or Tengis. The mountains are, the Imauan chain, or the Dark Mountains of Belur Tag ; those of the Russian frontier, and the mountains The island of Sagalian, or Tchoka, 240 miles north are adapted to agriculture; and the natives dress in loose robes of skin, and live in huts, a mild and intelligent race, un- like the Manshurs. - - - III. Tibet.—Tibet is about 1350 geographical miles long, and 480 broad, extending from the 75th to the 101st degree of east longitude; and from the 27th to the 35th degree of north lati- tude. It is divided into Upper, Middle, and Lower Tibet; the first comprising the province of Nagair, full of stupendous rocks, covered with eternal snow; the central region, embra- cing the provinces of Shang, Oti, and Kiang; while Lower Tibet includes the provinces of Takbo, Congbo, and Kahang. The religion of the Tibetians is closely allied with the Hindoo faith; but differs essentially in its ceremonies. For instance, the Tibetians assemble in temples, chant in alternate recitative and chorus, accompanied by instruments of music; and they have numerous monasteries, inhabited by hosts of gºlongs or monks, and annees or nuns. In a word, they resemble the Catholics. The ruling government is spiritual, but a secular regent manages the affairs of the half million of people who inhabit Tibet. The revenue of the Lama, or pope, and of the Secular princes, is triſting. And it is a remarkable fact, that, in regard to polygamy here, the women indulge themselves with pluralities of husbands. The chief city is Lassa, seven miles east of which is the palace of the Lama, or pope. Bridges of chain are common, passing from precipice to precipice. And though there is a great want of industry, the shawls of Cash- mir are manufactured from the goats’ hair of Tibet. The climate of Bootan is temperate, compared with that of Tibet Proper, whose distinguishing characteristics are extreme ari- dity and parching cold. And though Bootan be covered with eternal verdure, Tibet Proper presents a peculiarly naked aspect, indicative of rich ores. Its abundance and variety of wild fowl and game, its flocks of sheep and goats, and herds of cattle, have been noticed by all travellers, in all times. The chief river is the Sampoo or Burrampooter, but many of the Asiatic rivers have their sources in Tibet, whose mountains are the Alps of Asia. Japan.—Japan consists of several islands, extending from the 30th to the 41st degree of north latitude, and from the 131st to the 142d degree of east longitude. The chief of these islands are Nipon and Jesso; but the whole are divided into provinces and districts, with as much method as the most civilized countries of Europe. The established religion is polytheism ; the people abstain from animal food, and detest bloodshed; and viewing the gods as beings dispensing happiness, they solemnize their festivals and modes of worship with cheerful- ness and even gaiety; nor are they without monks and nuns of different orders, as in Tibet. The government is monarchi- cal, and each province is ruled by a resident prince, who, in pledge of his good administration, is obliged to leave his family as hostages at the émperor's court. And the laws being few, but rigidly enforced, without regard to persons, partiality, or violence, are posted up in every town and village. The popu- lation amounts to thirty millions of souls, and the army to 500,000 horse and foot. The revenue has been reckoned thirty millions. This highly civilized people use no wine or spiri- tuous liquors, though their food be various and their sauces numerous. Their dress consists of 'trowsers and loose gowns or robes of silk, worn alike by both sexes; and in their games and theatrical amusements the Japanese rival the Euro- peans. In varnishing they have no equals, and in some ot their arts and manufactures they excel even the British, the Germans, and the Chinese. The chief town, Jedo, is on the south-east side of Nipon, and Miaco, the spiritual capital, is the second city in the empire. The Dairi, or pope, resides here, and here also all books are printed from stereotype blocks. Japan is exposed to a copious moisture, from the R f 62 A S I A S I DICTIONARY OF MECHANICAL SCIENCE. rains which fall from midsummer to autumn, and the fertility of the country may be attributed to this cause; tempests, hur- ricanes, and earthquakes, are common. Agriculture is highly esteemed and sedulously cultivated, even on the mountains and hills; and the farmer labours under no restraint from taxes and tithes. Rice is the chief grain; but potatoes, beans, pease, turnips, and cabbages, abound. And the varnish and camphor trees, the vine and the cedar, and the tea-tree, are cultivated. Among the rivers and lakes described by geographers and travellers, we may enumerate the Nogafa, the Jedogawa, the Ojingawa, and the Jodo, as celebrated rivers; and one of the chief lakes seems to be that of Oitz. The mountains are numerous, and intermixed with many sublime volcanoes, and the delightful sacred mountain of Jesan is decorated with no fewer than 3000 temples. Among the islands dependent on Japan, is Fatfifo, the place of exile for disgraced grandees, and political offenders, who are spared capital punishment, to endure the more severe chastisement of perpetual banishment. The Birman Empire.—The Birman Empire includes the space between the 9th and 26th degrees of north latitude, and between the 92d and 107th degrees of longitude east of Green- wich ; about 1020 geographical miles in length, and 900 in breadth. The population amounts to seventeen millions; the government is despotic ; and a nobleman is distinguished by the number of chains, three, six, nine, or twelve, around his neck. The religion is that of Brahma, belief in the transmi- gration of souls, and eternal happiness in Mount-Meru. Their navy resembles the Roman galleys; and their army is incon- siderable, though every male is liable to military service. The Birmans are lively, irascible, and impatient; their women are laborious; hence infidelity, the offspring of idleness, is rarely known among them. The great alone are educated, the poor are totally neglected. The chief cities are, Ava, the ancient capital; Ummerapoora, the new capital, resembles Venice in its spires, turrets, and obelisks. It is built on the eastern side of a great river that flows into the Irrawady, amidst numerous islets. Pegu is known chiefly by the temples which Alompra spared when he razed the city in 1757. The Shomadoo, an extraordinary building of Pegu, is 361 feet high, surmounted by the sacred umbrella, fifty-six feet in circumference, and said to have been erected 500 years before Christ. Rangoon, the chief sea-port, contains 30,000 souls; Prome is celebrated as the scene of many sieges; and Aracan, Quantong, Bamoo, Munnipora, and Monchaboo, are considerable places. The inland navigation is most ample, from the numerous rivers and streams. The Birmans excel in gilding, and in carving marble divinities. The seasons are regular, the climate salubrious, and the people vigorous and healthful. The chief rivers are, the Irrawady, which joins the sea by many mouths; the Keen- Duem, the Sitang, and the Thaluan. And the mountains are those on the frontiers of Tibet, the range of Anoupee, between Ava and Aracan. The forests are large and numerous, and covered with everlasting verdure. The teak-tree flourishes as lord of the wood, in majesty of form and amplitude of growth. While in comparison of the Birman, our forests sink into vege- tables of an inferior order, their shrubs and plants in their blos- soms and fruits, by their brilliant colours and aromatic fra- grance, reduce to relative insignificance the boasted produce of Italian summers. * . - Aracan.—In Aracan, the climate is pure, the plains fertile, and the valleys present numerous flocks of cattle ; but the natives are averse to commerce and a maritime life. The Ara- cans will eat rats, mice, and serpents; and fish, to provoke the palate, must be out of season. The monarch lives in soli- tude and luxury with his queen and harem, which he thinks enriched by a concubine from Jangoma, a small kingdom in the vicinity of the Birman empire, and on the north of Siam. But the women of Jangoma are famed in all the east for their gallantry and beauty. The temples resemble pyramids, and there are three orders of priests, living in perpetual celibacy. Malaya, or Malacca.-Malaya is an extensive peninsula appended to the Birman territories, and divided into the kingdom of Patani in the north, and that of Johor in the south; the chief towns being Batusabar, the capital, Linga, Bintam, and Carimon. Malacca is 560 miles long and 150 broad; the inhabitants are indolent to agricultural pursuits, but restless barians. with abundance of wild elephants, whose teeth become a con- for, war, plunder, emigrations, and affairs of gallantry; and the Malayan history is full of desperate enterprises, that suffi- &iently characterize the ferocity of these Mahommedan bar- The peninsula of Malaya abounds in forests, stocked siderable article in the commerce of the natives with the Dutch and Portuguese. Opposite Malacca are the islands of Anda- man and Nicobar, whose inhabitants are the most savage in the world; but they may profit by the example of British industry, as a colony has been formed on the greater Andaman for convicts from Bengal. * * Siam.—Siam, 700 miles long, and 70 miles in medial breadth, is a rich and flourishing kingdom. The religion resembles that of the Hindoos ; the government is despotic ; the laws severe ; the people amount to eight millions; the army 60,000, with 4000 elephants; the navy is numerous, though the vessels are mere galleys; and there is a royal treasury, but its revenue is unknown to Europeans. The whole country is a wide vale between two ridges of hills, and would be a terres- trial paradise, were it not subject to an absurd despotism, that cramps industry, and would annihilate agriculture, did not vege- tation thrive in spite of the worst of governments. The Siamese are small of stature, but well made ; and their feed- ing on rats, mice, lizards, and several kinds of insects which we loathe, but ill accords with their religion, and the products of a country which exports prodigious quantities of grain. In all works of industry the women are employed, while the men pass away their time at theatrical amusements, races of oxen, combats of elephants, cock-fighting, tumbling, wrestling, rope- dancing, and exhibitions of fireworks. f - Laos, Cambodia, Siampa, Cochin-China, Tunquin.—Laos, though surrounded by forests and deserts, is fertile in rice, and furnishes the merchants of Cambodia with excellent ben- zoin and lacca, musk and rubies, gold and pearls ; and the people, in their religion and manners, resemble the Siamese. Cambodia is thinly peopled ; the capital, Cambaja, is a mere village of one street, with a single temple; and though the country. is fertile in rice and animal food, and abounds in ivory, and precious woods, the most peculiar product is gamboge gum, well known to artists for its fine yellow colour. Siampa is a small maritime country, south-east of Cambodia, and its prince is tributary to Cochin-China. Cochin-China presents an extensive range of sea-coast, and is divided into distinct provinces. Both sexes dress alike, in loose robes, with large long sleeves, cotton tunics and trowsers, with a turban on the head, but they walk barefooted; yet the Chinese display not more politeness than the Cochinians. Tunquin, divided from Cochin-China by a small river, resembles, in its people, terri- tory, and products, the Chinese empire. In the gulf of Tun- quin, tuffons are frequent and tremendous. They are preceded by very fine weather, a presaging cloud appears in the north- east, black near the horizon, caged with copper colour on the upper part, fading into a glaring white. It often exhibits a ghastly appearance twelve hours before it bursts; its rage lasts many hours from the north-east, attended with dreadful claps of thunder, large and frequent flashes of lightning, and exces- sive hard rains, when it sinks into a dead calm ; after which, it begins again with redoubled rage from the south-west, and continues an equal length of time. Hindostan.—Hindostan extends from about the 8th to the 35th degree of north latitude, or 1620 geographical miles; and from the 66th to the 92d degree of east longitude, or 1400 geographical miles. The population of this extensive portion of Asia is com- puted at 60,000,000; and the religion is polytheism; for the doc- trine of the Bramins, or priests, teaches beliefin a supreme Crea- tor, too ineffable and sublime for human adoration, which is, therefore, addressed to inferior, but great and powerful divinities. This superstition inculcates four casts or orders of the people: 1. The bramin (priest) from the mouth (wisdom) of Brahma, (the supreme ;) hence, the priests are supreme:—2. The cheh- teree, from the arms, (strength ;) to draw the bow, to fight, to govern : hence, governors, soldiers, &c. a middle class :—3. The brice, from the belly and thighs (nourishment;) to provide the necessaries of life by agriculture and traffic: hence farmers, merchants, &c.—4. The sooder, from the feet, (subjection;) to labour, to serve: hence, the slaves, or day-labourers, &c. The A S I A S I DICTIONARY OF MECHANICAL SCIENCE. Hindoos believe in the transmigration of the soul, and there- fore abstain from animal food, yet no where on earth are fana- tical penances, suicides, and superstitious frenzies, so common. They excel in the manufacture of cotton goods, of metals and . ivory, and shawls of Cashmir. . The loom in which cotton cloths, or shawls, are, woven, is a moveable frame, reared with the rising sun, beneath some shady trees, and transported to its owner's dwelling when the shades of night begin to leave the warp and the woof alike undistinguishable to the crafts- men. The native products are rice, sugar, spices, aromatics, drugs, and precious stones. The climate is diversified by local situation, as is also the aspect of this wide and extensive Country; but the periodical rains and intense heats produce luxuriance of vegetation elsewhere unknown, and none can be an indifferent spectator of the variety and richness of the vege- table kingdom of Hindostan. But then the soil is in many places a black mould four feet deep. The chief rivers are the Ganges and the Indus, the Burrampooter, the Sindé, and the Kistna, or sacred stream. The lakes are few, and consist chiefly of Colair, twelve miles, north of Masulipatam ; Chilka, a salt creek, communicating with the sea, as is also Pulicat; and Cashmir, supposed originally to have been a large lake, still boasts the Oullar, or Tall, fifty-three miles in circuit. The chief mountains are, the southern Tibetian Alps, shrouded in eternal snow, and hence called the Himmala; and the Gauts of Hindostan. Few maps can be relied on respecting the mountains of Hindostan; for in many instances the most recent are copied from the antiquated conjectures of D'Anville. The forests of Hindostan are large and exuberant of vegetation; but the loftiest tree is the palm. The cocoanut tree the most widely diffused; the cotton-tree, the banyan, the teak-tree, and the tamarind, with a numerous botanical collection, which we forbear to mention. The countries on the Ganges are the pro- vinces of Bengal, Bahar, Allahabad, Oude, Agra, with part of Delhi and Agimere, and of Malwa in the south, once the chosen seats of the Mogul power. Bengal, Bahar, with Benares, and some other districts to the west, are in the possession of the British. This extent of territory is not very exactly defined, and the population is, perhaps, not accurately estimated at 11,000,000 of black subjects. The clear revenue has been given at one million and a half; yet the East India Company has not been able to go on without parliamentary interference; and government has a Board of Control to watch over the Com- pany's proceedings. The government of Bengal is vested in a governor-general, who controls also the inferior governments of Madras on the east, and Bombay on the west, with Ben- coolen in the island of Sumatra. The British army, supported by the native infantry and cavalry, is now numerous; though the battle of Plassey, which established us in India, in 1757, was won by the invincible army of 900 Europeans; or in the ratio of 1 British soldier to 11% Hindoos. The chief cities are, Calcutta, the grand capital of British Asia; Patna, the capi- tal of Bahar, 400 miles north-west of Calcutta; Benares, on the northern bank of the Ganges, and 460 miles from Calcutta; Allahabad is the ancient, and Lucknou the present, capital of Oude ; Agra, Delhi, and Agimere. The countries on the river Sindeh, or Indus, are part of the provinces of Delhi and Agi- mere, the provinces of Moultan, Lahore, Cashmir, Cabul, Can- dabar, and Sindi, at the mouth of the Indus. The chief cities are, Lahore, Cashmir, Cabul, Ghismi, Candahar, Moultan, and Tatta. Lahore is the capital of the Seiks, a new religious sect. Cashmir is a filthy place, though the adjacent country is a deli- cious vale. The central division of Hindostan comprehends the province of Orissa, with part of Golconda, Berar, Dowlahabad, Candeish, Guzerat, and some other districts of inferior note. The Sircars, British provinces, skirt the eastern shore. The chief towns are, Amedabed, the capital of Guzerat, and Cambay, its sea-port; Surat, whose inhabitants are chiefly Moors, Persians, Monguls, and Turks; Bombay, situated on a small but well fortified island, with the isles of Salfatte, and Elephanta; Bur- hampour, Nagpour, Poona, Masulipatam, and Aurungabad, once the capital of the Deccan. The southern division of Hindostan is called the Deccan, extending from the latitude of Bombay, or 18% degrees north, to the southern point of Cape Comorin. This part of India nearly contains the whole pro- vince of Visiapour, part of Golconda, the central kingdom of Mysore, the long eastern province of Carnada, or the Carnatic, the principalities of Tanjore, Travancore, and the Samorins of Calicut, the pepper-coast of Canara, and other districts of minor note, with the island of Ceylon. . In the 10eccan the British power and influence are amazingly, extensive; for, besides Madras, and its adjacent territory, the possessions of the East India Company in the south of Hindostan, yield only in extent to those of the north on the Ganges. The chief cities are, Seringapatam, Salem, and Attore, in the east; Dindigul, Coimbetore, and Palicaud, on the south; Paniany, Ferokabad, and Calicut, on the western side ; and on the north, Tellicherri, Mangalore, and Carwar. Arcot is the capital of the Carnatic, or of Carnada. Tranquebar is a Danish settlement in Tanjore; Pondicherri was originally a French settlemefit. Vasco de Gama died at Cochin, on the Malabar coast, in 1525; and Goa is the noted seat of the horrible inquisition. Ceylon is about the size of Ireland, or 260 by 150 miles; and is important chiefly in a commercial view, from its celebrated cinnamon and gums. The religion is the ancient worship of Boodh. The population is not numerous, and the Ceylonese allow to the women a polygamy of the males, as in Tibet. The principal towns are, Kandi in the heart of the island, Colombo, and Trincomali, celebrated chiefly for its harbour. The air is cool and salubrious, and the mountainous districts, in the centre of the island, are covered with prodigious forests, stocked with aromatic trees, and the most odoriferous plants. The soil of the vales is rich, fertile in rice and useful vegetables; and numerous pleasant rivers, and delightful streams, diversify this isolated paradise, swarming with peacocks and other elegant birds. The Mahommedans believe Ceylon to have been the residence of Adam. The Laccadive and Maldive isles are near the coast of Hindostan. The latter, more than 1300 in number, are governed by a chief, called Atoll, and produce cowrie-shells, cocoa-nuts, and fish; the former, thirty in number, trade in cocoa-nuts, fish, and ambergris. : Persia.—Persia may be considered as divided into the eastern and western empires, and the independent provinces, near the Caspian sea. From east to west its length is about 1200 miles, and 1000 broad from north to south. The population is about 10,000,000, of which 6,000,000 are assigned to the western, and 4,000,000 to the eastern empire. The religion is the Mahomme- . dan, but there are still some Parsees, or worshippers of fire, near Baku, and at a place called Gusberabad, near Ispahan. The government is despotic, but its administration in Pandehar, the eastern empire, is extremely mild. The revenue is esti- mated at 3,000,000l. sterling. The provinces are, Georgia, Brivan, Aderbijan, Ghilan, Mazendran, Irac-Ajemi, Chosistan, Fars, or Persia Proper, Kerman, Laristan, Mekran, Segistan, Corasan; Balk and Great Bucharia belong rather to Inde- pendent Tartary. Persia is destitute of a navy, though enjoy- ing a great extent of sea-coast; and the maritime commerce is chiefly in the hands of foreigners, because the natives love rather to attend to their studs of horses, and the diversions of the chase, than to improve their own property, or to promote the prosperity of their country. The Persians are polite, hospitable, wise, and sagacious; the men strong and robust, remarkable for cleanliness, but subject to disorders of the eyes. The women are very beautiful; and amidst their abject super- stitions we notice chiefly astrology, that proud sophistry, which links the momentary existence of man with the eternal laws of far distant sums and worlds. The chief cities are, Ispahan, the capital; Huraz, celebrated for its delicious climate, and the exquisite salubrity of its atmosphere, perfumed by numer- ous fragrant flowers, and filled with the divine notes of the bulbul, or oriental nightingale. Tiflis, the capital of Georgia, is famous for its hot springs, and trade in furs; Derbent, on the Caspian sea, is productive of excellent grapes; Erivan, the capital of Persian Armenia, is not far from Mount-Ararat; Tauriz, in Aderbijan, is noted for its bazaars; and Rasht and Sari are the capitals of the Caspian provinces, Ghilan and Mazendran. Persia is famed for its carpets, its embroidery, porcelain, leather, sabres, silk, and bows, the trustiest in all the east. The climate is diversified, but excellent for the human constitution. The most singular feature in the face of the country, is its grand division into two parts, by mountains and deserts; and hence, though the northern provinces are 64 , A S I A S I DICTIONARY OF MECHANICAL SCIENCE. rich and fertile, those of the south, and even the centre, are unfertile, without extreme care to irrigation. The chief rivers are, the Euphrates and the Tigris, the Divrud and the Gihon, the Zeuderud, which passes by Ispahan, and the Bundamir, between Shirez and Iskakar. The principal lakes are those of Zeré, or Durra, in Segistan; the salt lake of Baktegan, fifty miles east of Shirez, lakes Urmia and Erivan. And the moun- tains most deserving of notice are, the Caucasus, to the west of Ghilan, and the south of Mazendran; the Persian Gulf chain; the grandest range is south of lake Urmia, where it is joined to the Caucasus; Mount-Ararat; Hetzardara, or the thousand mountains. The forests of Persia abound with deer, bears, boars, lions, tigers, and antelopes; the mountains with wild goats; the nuclerous wastes swarm with hares, wild asses, and hyaenas; and the flocks of large-tailed sheep augment in Erivan. The partridges are large and plentiful, and the pigeons excellent. Among the natural curiosities of Persia, the most remarkable is the inflammable naphtha, or pure rock- oil, found in the neighbourhood of Baku, on the western coast of the Caspian sea. Ormus is the most noted of the Persian isles, though it be now abandoned; and famous chiefly for its salt, which is collected on the rocks, from the spray of the sea, in a fit state for the table. Gombroon, or Kishma, and Karek, are ports of some importance in the Persian Gulf. Independent Tartary.--This singular region extends from the Caspian sea to the mountains of Belur, or 870 miles east and west; and from the mountains of Gaur in the south, to the Russian boundaries, on the north of the desert of Issim, or about 1500 miles. The chief divisions are, the barren plains in the north, inhabited by the several hordes of Kirguses, called anciently Turkistan; Ilak and Shash, the most northern pro- vinces, on the Sihon, are on the south of the Argun mountains; Fregana and Orushna, with the kingdom of Kharizm ; south of the Ak-Tau, or, white mountains, are the fertile provinces of Sogd, Balk, Kilau, Tokarestan, and Gaur. The chief towns are, Cashgar and Yarcaud, Axu and Yulduz, or Karashar, (the black city ;) Turfan, and Hami, or Camil. The prevailing religion is the Mahommedan. The inhabitants are polite and benevolent Kirguses, about half a million of souls, Bucharians and KalmuckTartars, expertin the lance,the sabre, and the bow. The desert of Issim divides the Kirguses from Siberia; and the three great hordes of these people live in tents, leading a wandering life, regarding each other as brethren, rearing vast herds of cattle and horses, and delighting in the chase of wolves, foxes, badgers, antelopes, wild asses, chamois, and tigers. The Kirgusians trade with Russia, supplying annually 150,000 sheep, vast troops of horses, and abundance of wool; and in exchange they receive clothes and, furniture, and from Bucharia arms and coats of mail.—Khanrizm, a province of independent Tartary, extends from the Gihor, to the Caspian sea, about 350 miles long, by as many broad; its chief town is Khiva is seventeen days’ journey from the Caspian sea, and thirty-three from Orenhurg. The coasts of the Cas- pian are held by Turkomans in the north, and Uzbeks in the south.--Great Bucharia, the most important part of Indepen- dent Tartary, extends 700 miles in length from north to south, Khiva. and 350 miles in breadth from east to west. The mountains of Argun bound it on the north, the river Armu on the west, and on the south and east, the mountains of Gaur and Belur. The religion is the Mahommedan; the government is despotic ; and the Uzbeks and Bucharians are the most spirited, and industrious, amidst surrounding barbarians. But the Bucha- rians never bear arms, though the women of the Uzbecks, sur- passing those of the other Tartars in beauty, fail not to follow - - , , The provinces, of Great their lords to the field of battle. - g Bucharia are, Fergana, Andegan, Sogd, Kottan and Kilan, "okarestan, and Gaur. And the chief cities are, Samarkand, Bokhara, Balk, Zouf, or Gaur, Badakshan, and Kotlan. Sa- markand was famous for its manufacture of silk paper, as early as A.D. 650; Bokhara, for its fine linen, was distinguished even in the tenth century; Balk, for its beautiful silks; Gaur, for its rich quarriès of lapis lazuli; and Badakshan, included in the Hºs used as a state-prison, for rivals, or insur- gents, against the khan of Great Bücharia. Situated in the arallel of Spain and Greece, the climate of Bucharia is excel- lent. The soil adjacent to the rivers is fertile, but neglected. The chief rivers are, the Armu, and Sirr, or Shash; the island seas are the seas of Aral and Baikal, and the lakes are those of Tengis and Balkash; and the chief mountains are those of Belur, of Gaur, the Hindoo-Kob, of Argun, of Kara-Tau, and Ak-Tau, Ebu Haukal says, all the families of Independent Tartary are but one house; and, in Sogd, he saw a great building, whose doors were fastened back with nails against the walls, continuing thus open night and day, for above 100 years, that strangers, who should arrive at the most unseason- able hours, might find no obstacle to enter, and receive every thing necessary both for man and beast. - Arabia.—Arabia, bounded by the Red Sea, the Indian Ocean, and the Persian Gulf, on the west, south, and east, and on the north by the Mediterranean and Palestine, is about 1800 miles from north to south, and 800 broad. The centre of Arabia is a vast desert. The provinces situated on the sea-coast are fertile in millet, barley, beans, lentils, rape, sugar-cane, tobacco, cotton, valuable spices, pomegranates, melons, and coffee. The religion is the Mahommedan, but a new sect, called Wahabees, has made considerable progress. This sect has derived its name from one Abdul Waheb, a sheik, or imam, in the pro- vince of El-Ared. A sheik (old man) is a governor of a pro- vince, and an imam (vicar) is an ecclesiastical ruler, as the twelve imams, the genuine successors of Mahomet, in Persia. In Arabia, an imam is a calif, or prince of the faithful. The Arabians are polite and hospitable, temperate in eating, and abstemious, of wine. The women dye their nails of a Scarlet colour, their feet and hands of a yellowish brown, and no art is left unemployed to make the eye-brows large and black. Many of the poorest people read and write, as education is attended to very generally, and the chief cities are celebrated for colleges and academies. The holy cities are Mecca and Medina. Gedda, a sea-port, forty miles distant from. Mecca, was famous in ancient times, when the markets of Saana and Merab, and the harbours of Oman and Aden, received the precious cargoes of aromatics brought thither by the hardy camels of the Koreishites. Now, Mecca, the birth-place of Mahomet, is governed by a sherif, who is a temporal prince; and Medina, 200 miles north of Mecca, contains the tomb of the prophet. Sana, in Yemen, at the foot of a mountain called Nikkum, about four miles in circuit, is now the chief . city of Arabia. Mocha is noted for its having one glass-house. The chief rivers are, the Euphrates and the Tigris, flowing through Irak-Arabia; and the chief range of mountains pro- ceeds in the direction of the Red Sea, while the hills of Omon are merely a continuation of those on the other side of the Persian Gulf. Mount-Sinai is in Arabia-Petraea; and in the country of Seger there is a range of hills famous for producing frankincense. The horses of Arabia have long been celebrated : and the Kochlani breed are direct from the stalls of Solomon. But the chief animal is the camel, the ship of the desert. And the woods of Yemen abound in numerous monkeys; the jer- boa, or rat of Pharaoh, is found in Neget; and wherever the mountains originate springs, to scatter verdure and fragrance, the antelope is there; and the wild oxen, wolves, foxes, and boars, pasture the woods, or prey on their inmates. The islands belonging to Arabia, are Socotra, in the Arabian Gulf, or Red Sea, about 240 miles from the southern coast, and celebrated for its aloes; and the isle of Bahrin, in the Persian Gulf, noted for its productive pearl fishery. . . . . . . . . The Asiatic Islands.-These islands comprise those of the oriental archipelago; Australasia, and Polynesia. In the archipelago are the islands of Sunda, or, the Sumatran chain, comprising Sumatra, Java, Balli, Lombok, Sumbava, Flores, and Timor. Sumatra, 950 miles long, and 200 broad, has an English settlement at Bencoolen. Though frost, snow, and hail, be unknown, the inland inhabitants of the mountainous districts use fire to dispél the cold; for true it is that a man may be frozen to death in the torrid zone. But these inland races are savages, covered with red hair, and little superior to the orang-outangs of Borneo. The elephant, the rhinoceros, the hippopotamus, the tiger, the bear, the otter, the porcupine, the wild hog, and the civet cat; herds of deer and troops of monkeys; wild poultry, the Argus pheasant, and swarms of destructive termites, comprise part of its zoology; Java, 650 miles long by 100 broad, is well known for its Dutch capital, A S I. A S I 65 DICTſ ONARY OF MECHANICAL SCIENCE. Batavia, which is, in fact, the metropolis of the eastern archi- pelago. But Java is an unhealthy place, and “of three settlers it is rare that one outlives the year;” yet, to Batavia, Euro- peans and Chinese resort, the latter being contented, for the sake of gain, to forget the tombs of their ancestors, and the laws of Confucius, which interdict emigration. Balli furnishes slaves and cotton, the others spices ; and the people of Timor. are the bravest of these Oriental islanders.-Borneo, except New Holland, is the largest island in the world, being 900 miles in length, by 600 in breadth. The coasts are possessed by Malays, Moors, Macassars, from Celebez, and even Japa- nese. The natives in the interior are blacks, called Biajos, with lanky hair, of middle size, feeble, and inactive. Thou- sands of ourang-outangs are seen amidst the swamps and forests of this island. A knight of Borneo is known by his string of tigers’ teeth, a chief of a tribe by having two of his front teeth replaced by two gold teeth. The capital of the island consists of 3000 houses built on posts, fixed in rafts, which are moored to the shore, and may be moved from place to place, according to the convenience or the caprice of the owners. The Manillas, or Phillippine islands, occupy a space of 20° of latitude, in the longitude of 120° and 130° east of Greenwich; and form a north-eastern frontier to the island of Borneo. Luzon, the largest of these islands, is 500 miles long, and 100 broad; and its chief city, Manilla, boasts a population of 12,000 Christians, mostly Spa- niards. For it was between this island and Acapulco, that the Spanish galleons carried on their celebrated commerce, through a space of 8,400 miles of the ocean.—Mindanao is mountainous, but the vales are rich, being watered by mumer- ous crystalline rivulets; and horses and buffaloes swarm in the interior. The remaining Phillippine islands are, Pulawain, Mindoro, Pani, Buglas, or the Isle of Negroes, Zebu, or Leita, and Samar. Maetan, a small isle, on the east of Zebu, is the place where the celebrated navigator, Magellan, was slain. These islands present many volcanic appearances; such as lava, volcanic glass, sulphur, and hot springs; and the bread-fruit extends its beneficial arms to the hundreds of islands that sprinkle the Indian and Pacific oceans.—The Celebezian Group, or the isles of Poison, are Celebez, Sanguy, Shullas, Peling, Boutan, and Sala. Celebez is 600 miles long, and about 60 broad, considering the extensive bays that chequer its coast. In its centre there are several live volcanoes. From the mountains, rivers precipitate themselves over vast rocks. The natives are called Macassars, and are famed most for their pusillanimous attacks on solitary vessels, with lances and arrows, poisoned with the juice of the deadly upas. Though these islands produce spices and rice, their botany is full of poisonous trees and plants.-The Moluccas are, Ternah, Tidore, Motir, Makian, and Bakian. Ternah is the retreat of the kingfisher, clothed in scarlet and mazareen blue; Tidore boasts five-and-twenty mosques, and its Sultan claims tribute of Gilolo; Motir is the seat of Venus and voluptuousness; Makian rises out of the sea like a sugar-loaf; and Bakian is famed for its prodigious rocks of coral, of infinite variety and beauty,+The Spice Islands, are Gilolo, Ceram, Bouro, Mortay, Oubi, Mysol, Amboyna, and Banda. Gilolo, once governed by a sheref from Mecca, proves how far the Mahommedan conquests had extended. The natives are good weavers, and have plenty of oxen, buffaloes, goats, deer, and wild hogs, with bread-fruit and sago trees. Ceram abounds in clove trees, and large forests of sago trees; Bouro possesses the civet weasel, green-ebony, iron-wood, &c.; Mortay is full of Sago trees; Mysol of birds of paradise; Oubi produces cloves; Amboyna boasts of a population of 17,800 Dutch Protestants; and 27,000 Mahommedans, Chinese, and savages. The clove tree in this island grows to the amazing height of forty or fifty feet, and will yield thirty pounds weight annually. But Banda is the chief isle in this group, furnishing 160,000 pounds weight of nutmegs, and 46,000 pounds of mace annually. The nutmeg tree grows to the size of the pear tree in our orchards; its leaves resemble those of the laurel; and from the age of 10 to 100 years it bears fruit. The nutmeg, on the tree, is about the size and colour of an apricot, but shaped like a pear. When ripe, the rind bursts, and discovers the mace, of a deep red, covering in part the thin shell of the nutmeg. A Australasia.-Australasia contains New Holland, Papua, or New Guinea, New Britain, and New Ireland, with the Solomon Isles; New Caledonia, and the New Hebrides, New Zealand ; and Van Diemen's Land. New Holland is the largest island in the world, and some progress is now making in exploring its interior. From east to west it is 2,730 miles over ; and from north to south 1,960 miles. The original inhabitants are harmless savages, grossly ignorant, believing in magic, witch- craft, and ghosts At Port Jackson a colony has been formed for British convicts; but numerous free settlers are now established on the island, and it will, ere long, be famous, since the breed of sheep there rivals the Spanish Merinos, and the soil is excellent for grain. Papua, or New Guinea, par- takes of the opulence, of the Moluccas, with their singular varieties of plants and animals. And in the interior a race of savages, called Haraforas, live in trees, which they ascend by a notched pole, drawing it after them, to prevent surprise. The women are industrious, the men indolent, but fond of orna- ments, as the tusks of boars around their necks, and feathers. of the bird of paradise stuck in their woolly hair. Papua is the chosen abode of that splendid bird, of elegant parrots, and the crowned gigantic pigeon, nearly as big, as a Norfolk turkey. New Britain resembles Papua in its inhabitants and products. The canoes of New Ireland are ninety feet long, formed out of single trees; and the inhabitants of the Solomon isles orna- ment their necks with gold beads. New-Caledonia, and the New Hebrides, have more intelligent inhabitants than we have lately been among, for their houses have carved door-posts, and the women are more chaste than in the other isles of the Pacific. Plantains, sugar-canes, yams, and several kinds of fruit-trees, are found in the Hebrides, whose natives are very dexterous in launching the spear, with unerring certainty. New Zealand consists of two large islands, which enjoy a tem- perate climate, equal to that of France; and the people believe that, the third day after they inter their dead, the heart is separated from the body, and carried to the clouds by an attendant spirit. Van Diemen's Land, an island situated south of New Holland, is about 160 miles, long, and 80 broad. The natives and the products resemble those of New Zealand and New Holland. Polynesia.-Polynesia is divided into the following islands, or groups.-The Pellew Islands, inhabited by a gentle and amiable race of industrious savages; the gay and innocent children of nature, united in one large family, by that concen- tration of society which small islands impose on their natives. The Ladrones, or Marians, of which the largest are Guam and Tinian, are inhabited by a people who resemble the natives of the Phillippines. These islands are fourteen in number, but only three are inhabited. North of the Ladrones are many small islands, with a few scattered islands on the north of the Carolines, that have not been classed and named. The Caro- lines, about thirty in number, are very populous, and the natives, like those of the Phillippines, live chiefly upon fish and cocoa-nuts. The three principal of these islands are, Hog- oleu, Yap, and Ulea. The Sandwich Isles were discovered by Captain Cook, at the chief of which, Owhyhee, he lost his life. The inhabitants are mild, affable, and ingenious, but human sacrifices are frequent. The climate is more temperate than that of the West Indies. Dogs, hogs, and rats, are the native quadrupeds. The birds are pigeons, plovers, owls, and ravens. The bread-fruit tree abounds, and sugar-canes grow to an amazing size. The Marquesas boast no island half so large as Otaheite. Noabeva, the chief island of the Marquesas, is only about sixty miles in circumference. The natives possess the most exquisite symmetry of shape and regularity of features, and the women are as fair as the females in Italy and Spain; but mutual slaughter and human sacrifices prevail. The Society Islands annount to about seventy in number, of which Otaheite is the chief, being about 120 miles in circumference. The men are olive-coloured, the women brunettes, with fine black eyes, white and even teeth, soft skin, elegant limbs, jet- black hair, perfumed, and ornamented with flowers; but still they are inferior in beauty to the women of the Marquesas ; nor do any of the females of the South-sea islands possess the Grecian forms and academical precision of feminine beauty. But the Otaheiteans are the Italians of the Great Pacific S 66 A S S A S S * DICTIONARY OF MECHANICAL SCIENCE. Ocean in language and politeness, and in the romantic scenery of their country. Infants swim as soon as they can walk. The Friendly Islands, including the Feejee isles, the Navigators’ islands, and several more northerly and detached isles, are peopled by men of grave and regular behaviour, who are governed by despotic chiefs. The largest of these islands are, Pola, Tongataboo, Oyolava, Maouna, and Opoun. Pro- visions are amazingly plentiful in these islands. The men are of great stature, the women pretty and licentious. The inha- bitants of all Australasia and Polynesia do not, perhaps, amount to 300,000 souls. The speech diffused throughout all the scattered islands of Polynesia is derived from the Malayan. The trees and plants peculiar to the tropical Pacific islands, are the bread-fruit tree, the plantain, the cocoa, the sugar- cane, figs, sweet potatoes, &c. ASILUS, hornet fly. ASPALATHUS, African broom. ASPARAGUS, or Sparrow Grass, one of the greatest deli- cacies which our kitchen-garden affords, being particularly estimable from the early season at which it is produced. The asparagus is raised from seed, in beds formed for the purpose; and the plants should remain three years in the ground before they are cut; after which, for a dozen years, they will continue to afford a regular crop. In the Editor's garden there are some very fine beds about twenty years old. ASPECT, the situation of the planets with respect to each other; there are 5 aspects: 1st, Sextile, marked k, when the planets are 600 distant; 2dly, Quartile D, at 90°; 3dly, Trine, when 120° A ; 4thly, Opposition 3, when 1809; and 5thly, Con- junction 3, when both in the same degree. ASPEN TREE, the trembling poplar, flourishes in any situation; the wood, though good for packsaddles, milk pails, clogs, and wood-work for pattens, is very bad for beds, as it promotes insects. ASPERIFOLIOUS, in Botany, one of the divisions or classes of plants in the Linnean system ; so denominated because they are usually rough-leaved. ASPERUGO, small wild bugloss. ASPERULA, wood roof. ASPHALTUM, bitumen Indiacum, pitch formed on the surface of the Dead Sea, and which was formerly employed in embalming the bodies of the dead.* ASPHODELUS, king's spear, asphodel. ASS, a species of aequus, or horse. When very young, the ass is sprightly, and even tolerably handsome ; but he soon loses these qualities, and becomes dull, stupid, and headstrong. But he is not equally stupid in all countries; for in Spain, and some other countries, he is much more elegant and tractable ; and if treated with care, there is no doubt that he might be rendered much more serviceable to us than he now is. Wild asses are fierce, swift, and formidable, and, when pursued, will defend themselves with courage. ASSA-FOETIDA, the concrete juice or resinous gum of a large umbelliferous plant, growing in India and Persia. The Banian Indians use it in all their dishes; our own cooks sub- stitute it for garlic. In Arabia and Persia it is used both internally and externally as a medicine. It is an excellent cure for the hooping cough and for worms; in flatulent colics, &c. ASSAULT, an attempt to offer to beat another without touching him ; as if one lifts up his cane, a whip, or his fist, to hit another, or strikes at him, but misses him. The party injured may have redress by action of trespass vi et armis, wherein he shall receive damages as a compensation for injury. This teaches society the exterior formula of good breeding; but the temperament of an Englishman pricks him to repel force by force ; and to repay by an eye for an eye, or a tooth for a tooth, without trusting to the doubtful issue of trespass, per to- gam pecuniamque. ASSAYING. There are two kinds of assaying; one before metals are melted, the other after they have been struck; the first brings them to their proper fineness, and the last compares them with the standard. For the first assayers take 14 or 15 grains of gold, and half a drachm of silver, if it be for money ; and 18 grains of the one, and a drachm of the other, if for other uses. The second assay is made of one of the pieces of money, which is cut into four parts. The quantity of gold for an assay is here six grains. ...Assaying is also the particular mode of examining every ore and mixed metal, according to its mature, with the proper fluxes, to discover not only what metals, with their proportions, are contained in-dres, but also the quantity of sulphur, vitriol, alum, arsenic, and othermatters. Gold is obtained pure by dissolving it in nitro-muriatic acid, and precipitating the metal by dropping in a diluted solution of sulphate of iron : the powder which precipitates is pure gold. Silver is obtained ‘pure by dissolving it in nitric acid, and precipitating it with a diluted solution of sulphate of iron. With metallurgists the mass consists of 24 imaginary parts, called carats. Gold of 24 carats means pure gold : the number of carats mentioned specifies the parts of pure gold, and what that number wants of 24 carats, indicates the quantity of base metal in the alloy. Gold of 12 carats, means 12 parts of gold and 12 of another metal. Gold coins of Great Britain are of 22 carats fine ; they contain, therefore, 11 parts of gold and one of copper. Parting is the separation of gold from silver, when both are contained in an alloy; and it is founded on the insolubility of gold, and the solubility of silver in nitric acid. - Fig. 108. Ass A Y BALANCE, is of very -- *-* -º- ºm. º 'little different construction from the common scales, having a beam from 10 to 12 inches, and being made of the best steel. The beam is suspended in a fork, and as the balance will hardly stand still in the open air, it must be put into a case, as represented in the figure. A ſ - I pair of pincers are used to put | | articles to be weighed into this d balance; or if the article be a powder, a small shovel or spoon. ASSIZE, an assembly of knights, and other substantial men, together with a justice, in a certain place, and at a certain time, when and where the writs, processes, whether civil or criminal, are decided by a jury, directed by a judge. If a man has been charged with an offence, before he can be put on his trial, the charge must first be examined by an impartial grand jury of 23 persons; twelve of whom, at least, must agree to find a bill of indictment, which being found, he then undergoes a public trial before twelve of his equals. The powers of a grand jury are most extensive, and their duties being most important, it is necessary that they be performed with the greatest care, intelligence, and impartiality. Bills ought never to be found lightly, on frivolous pretences, or imperfect evi- dence; and as grand juries only hear the evidence of the prosecutor, they ought to be vigilantly on their guard against trifling, vexatious, and malicious prosecutions. The petit jury of twelve make oath, that “they shall well and truly try, and true deliverance make, between the king and the prisoner at the bar, according to the evidence.” After they have fully heard the evidence, the prisoner's defence, and the law from the judge, the twelve must decide each for himself, and the whole must be unanimous in acquitting, or in condemning, the prisoner. The jury must be impartial and independent, or they are liable to be challenged or objected to. They should also found their verdict on their own judgment, deducing it from clear and positive evidence : no other duty being so sacred, and no other trust so great, as that reposed in the integrity and independence of a juryman. ASSOCIATION of IDEAs, is when two or more ideas con- stantly and immediately follow or succeed one another in the mind, so that one shall constantly and infallibly succeed another. The influence of association in regulating the succession of our thoughts, is a fact familiar to all men: that one thought is often suggested to the mind by another, and that the sight of an external object often recalls former occurrences, and revives former feelings, are indisputable facts. This subject is very fully treated in the Editor's Grammar of Logic and Intellectual Philosophy. See chap. vii. book ii. of that work, second edition. - ASSUMPSIT, in Law, a voluntary or verbal promise, whereby a person assumes, or takes upon him, to pay anything * to another. There are numerous cases of assumpsit on record. 'A S S. ' A S T .67 DICTIONARY OF MECHANICAL SCIENCE. Thus all notes of hand, bills of exchange, &c. come under this name ; and so of many other covenants, verbal or written. ASSUMPTIVE ARMs, in Heraldry. Thus, if a soldier, who has no right by blood to arms, or if he have none, shall in war captivate any gentleman, nobleman, or prince, he may then assume the arms of his prisoner, and enjoy them in his heirs for ever. ASSURANCE ON Lives. By assuring a life, is meant obtaining security for a sum to be received, should the life drop, in consideration of such a payment made to the assurer, as shall be a sufficient compensation for the loss and hazard to which he exposes himself. In estimating this compensation, the amount of it will depend entirely on the rate of interest at which money is improved, and the probable duration of the life of the individual. In order to illustrate this, let £100 be supposed to be assured on a life for a year to come, supposing money to bear an interest of 5 per cent. Now, first, if it were certain that the life would become extinct in the course of the year, the premium would be the present value of £100, payable a year hence, which at 5 per cent. would be £95.4s. 8d. ; but if, instead of the certain extinction of the life, it be known from the regular bills of mortality, that out of 1000 persons of the age of the assured, only 250 fall in the course of a year, or 250 1000 failing, then } of the above premium will be the fair compensa- tion to be received by the assurer: and as there have been tables of the decrease of human life kept for many years, in various parts of this and other kingdoms, the calculation of the fair premium to be paid for any age, for a year, is extremely simple, and needs no farther illustration. But the assurances most commonly practised, are those on single lives, either for a given term, or during their whole continuance; and the pre- mium is either paid in a single present payment, or in annual payments during the said term, or till the life fails; in both which cases the calculation becomes more complicated. On the most equitable principles, tables have been computed which exhibit at one view the annual payment that ought to be made to assure a life, at any age, for £100; and which, therefore, is equally applicable for any other sum, by a simple operation of multiplication and division; these annual payments vary a little in different offices, but the most general terms and condi- tions are as follows:—The person making the assurance is to declare the place and date of birth of the person whose life is to be assured ; whether he have had the small-pox ; whether subject to the gout; and whether in the army or navy. Conditions of Assurance made by Persons on their own Lives.— The assurance to be void, if the person whose life is assured shall depart beyond the limits of Europe, shall die upon the seas, (except in his majesty’s packets passing between Great Britain and Ireland,) or shall enter into or engage in any military or naval service whatever, without the previous con- sent of the company; or shall die by suicide, duelling, or the hand of justice; or shall not be, at the time the assurance is made, in good health. Conditions of Assurance made by Persons on the Lives of others. —The assurance to be void, if the person whose life is assured shall depart beyond the limits of Europe, shall die upon the seas, (except in his majesty’s packets passing between Great Britain and Ireland,) or shall enter into, or engage in any military or naval service whatever, without the previous con- sent of the company; or shall not be, at the time the assurance is made, in good health. These rules are varied conditionally in some assurance offices; but we have exhibited the general principles. Any person making an assurance on the life of another, must be interested therein, agreeably to act of 14th, of Geo. III. chap. 48, which prohibits wagering, or speculative InSU ran CôS. Since the foregoing was written for this work, some new assurance associations have arisen, which take numerous risks that the old offices would not assure; and it matters not now, whether a man belong to the army, the navy, or any other service equally hazardous: he may assure at some of these new offices with as much facility as a tradesman could do at the Sun, the Equitable, or the Rock life-assurance offices. which is the same, if , or 3, represent the prospect of its TABle of PREMIUMs, For Assurvng the Sum of One Hundred Pounds upon the Life of any healthy Person, from the Age of Eight to Sialty-seven. 7 Yrs. atl The whole R 7 Yrs. at . The whole >| One an ann. Life, at an ; ºr One an ann. Life, at an * ! Year. loavment lannual pay- $ º Year. payment annual pay- º pay * of ment of : of ment of * £. s. d.ſ.f. s. d. 36. s, d. ..]+, s d.lf. s. d. f. s. d. 14|0 17 91 1 5|| 1 17 7 § 412 2 0|2 5 4 3 9 9 15 0 17 Il 1 2 11 || 1 18 7 x 42|2 3 612 6 6 || 3 11 8 16|0 19 2 || 4 7 || 1 19 8 : 432 4 6|2 7 9| 3 13 8 |; ; ;|| 3 || 3 | $44; ; ; ; ; ; ; , , 18|1 3 3|l 7 5| 2 1 8 ; 45|2 6 8|2 10 10| 3 17 11 19||1 5 0 \l 8 6. 2 2 8 x 46]2 7 10 |2- 12 6 || 4 0 2 20|| 7 3|1 9 5| 2 3 7 : 47|2 9 0|2 14 4| 4 2 7 21 || 8 10|1 10 1 2 4 6 5 48 |2 10 3 |2 16 4 || 4 5 1 22 || 9 3|1 10 6| 2 5 4 $49|2 12 3|2 18 6|| 4 7 10 23|l 9 8|1 11 0 || 2 6 3 ; 50|2 15 I 3 0 8 || 4 10 8 24|1 10 21 11 6|| 2 7 I : 512 17 4|3 2 8; 4 13 6 23|| 0 || 2 || 2 : , ; 52]; 19 || 4 || 4 13 5 #|}}} }} }; ; ; ; ; ; ; ; ; ; ; ; ; ; ; 23|i 12 it is g| 2 iſ $555 5 off 13 of 5 g . 29|1 12 8|1 14 4| 2 12 3 ; 56|3 7 3|3 14 8 5 10 1 30|| 13 3||114 11| 2 13 5 : 57|3 9 8|3 17 G| 5 14 0 ;|| || || || || 3: ; ; ; ; ; ; ; ; ; ; ; ; * 33 || 15 0|1 16 10| 2 17 1 $ 60|3 18 1|4 7 1| 6 7 4 34|| 15 8|1, 17 8. 2 18 5 § 61|4 1 5|4 10 11 6 12 4 35|l 16 4|1 18 10] 2 19 10 $ 62|4 3 114 15 0 || 6 17 9 *H # º : * : ; : 1. § 63|4 7 3/4 19 8 7 3 7 2 : *|| 0 || 4 || 7 | 1Q 38|| 18 G|2 1 9| 3 4 6 : 65|4 15 25 10 10 T 16 9 39]1 19 3|2 2 11] 3 6 2 : 66|5 0 1 |5 17 7| 8 4 1 40|2 0 82 4 1] 3 7 11 : 675 5 66 5 * 8 12 1 l & * ASTER, in Botany, Starwort, so called as having a radiated flower. - ASTERIA, the goshawk; also the gem cat's eye: the name also of an extraneous fossil, known as star-stone. ASTERIAS, the star fish, or sea star. ASTERION and CHARA, or Canes Wenatici, the Greyhounds. This constellation was introduced by Hevelius. It occupies the western space between Boötes and the hind legs of Ursa Major, and is easily distinguished by a star of the 3d magni- tude on the neck of Chara, forming a triangle with y and m, in the hip and tail of Ursa Major. Sir Charles Scarborough, physician to Charles II. called this star Cor Caroli, or Charles's Heart, in honour of king Charles I. A-STERN, denotes any distance behind a ship, as opposed to A-HEAD. ASTRAGAL, in Architecture, a round moulding, which, in the orders, surrounds the top of the shaft or body of the column; it is used also at the bottoms as well as the tops of columns; and properly represents a ring on whatever part of a column it is placed.—In Anatomy, the upper bone of the tarsus, which, by its conjunction with the bories of the leg, forms the ankle- joint. ASTRAGALUS, milk, or liquorice vetch. ASTRANTIA, masterwort. ASTRINGENTS, in Medicine, are distinguished by a rough austere taste, and the property of changing solutions of iron, especially those made in the vitriolic acid, into a dark purple or black colour; such as galls, tormentil root, terra japonica, acacia, &c. - * ASTROITES, star stone. ASTROLABE, a stereographic projection of the sphere, which, among the ancients, was equivalent to the armillary sphere, or armed by proper graduations, &c. it enabled an observer to take the altitude of the sun, or of a star. ASTROLOGY, a conjectural science, founded upon certain supposed effects, influences, positions, and situations of the stars, with a view to predict future events from their aspects, &c. It surprises one, that our almanack makers should still repeat the nonsensical stuff of Lilly, Moore, and other clever 68 A S 'T A s T. DIGTIon ARY OF MECHANICAL SCIENCE. men, who reigned in the ages of judicial, perhaps natural, astrology. ... . ĀsīāonoMY, the science which teaches the motions of the Earth, the Sun, Moon, Planets, Comets, and Stars, and explains the phenomena occasioned by those motions, is divided into two parts: 1st. that which treats of the motions, magnitudes, and periods of the revolutions of the heavenly bodies, and is called pure or plain Astronomy; 2d. that which investigates the causes and laws by which these motions are regulated. The student of astronomy, may, in the day time, obáerve one of the chief of these motions in the rising, ascent, exaltation, declension, and setting of the sun. In the morning he will see it rise in the eastern heavens, ascend in this hemi- sphere towards the south, attain its greatest height at noon, and then descend again, till it sets in the west, as far from the south as it rose in the morning. This is the first practical Iesson in astronomy. In the night time he may observe the stars rise in the east, ascend towards the south, and decline and set to the west; and this will be the second lesson. He may, however, observe, that one star, viz. that over the North Pole, never moves, and that all the others move around it, and those within a certain distance never set; and, in short, in this third lesson, which is worthy of being pursued through succes: sive evenings, he will become master of the general motions of the heavens. Thus, by measuring, for example, at London, during a long winter's night, the two meridian heights of the Polar Star, (a Ursae Minoris, having 88° 20'49" declination N.) we find that (ann. 1820) * When it passes above the Pole, its altitude \ 530 10' 11" IIleaSU reS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . § And when it passes below the Pole, it 490 51' 49” IſleaSu TeS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . $ The sum of which is . . . . . . . e - e º e e s e s s s e s & a 1030 02' 00" And their half. . . . . . . . . . . . . . . . . . . . . . . . . . . . 510 31' 00" Which will be the altitude of the Pole above the horizon of London, or the distance of this city from the equator. If, on the contrary, we subtract 49° 51' 49" from 53° 10' 11", we shall find for their difference 3° 18' 22", of which the half, 19 39' 11", will give the distance of the Polar Star from the Pole (in 1820), which we thus find does not exactly occupy this point, but is yet very near to it. He will observe, in a fourth lesson, which is also to be pursued through successive nights, that the moon changes her place with regard to the stars, that she increases in light in proportion to her increased distance from the sun, till she arrives at the opposite, or rises as the Sun sets; and that the light increases on one side, and decreases on the other, being always towards the sun. He will, in like manner, observe, that the planets change their motions slowly in regard to the fixed stars, and that both the moon and the planets move in the same line, or nearly so, among the fixed stars; and this fifth lesson may be mixed with others through successive weeks. He will be highly gratified by applying any telescope (the larger the better, but the smallest will afford much gratification) to the moon, planets, afīd stars. He will observe the decrease and increase, and change of the shadows of the moon's pits; the satellites of Jupiter; the moon-like appearance of Venus; the ring and moons of Saturn; and many of the constellations and nebulous clusters of stars. The heavenly bodies that we are to notice, are, the Sun, the Planets, Comets, and Fiaced Stars. s The Sun gives name to the system of Astronomy, which Copernicus, Kepler, and Newton have established, but which was known in the East 4000 years ago, in its general appear- ances, as perfectly as by La Place in our own times. The solar system is so called, because the Sun is supposed to be situated in a certain point, termed the centre of the system, having all the planets revolving round him at different dis- tances, and in different periods of time. This is likewise called the Copernican system. See Plate Solar System. - The SUN, situated near the centre of the orbits of all the planets, revolves on its axis in 25 days 14 hours 4 minutes. This revolution is determined from the motion of the spots on its surface, which first make their appearance on the eastern extremity, and then by degrees come forwards towards the middle, and so pass on till they reach the western edge, and then disappear. When they have been absent for nearly the same period of time which they were visible, they appear again as at first, finishing their entire circuit in 27 days 12 hours 20 miautes.*. The Sun is likewise agitated by a small motion round the centre of gravity of the solar system, occasioned by the various attractions of the surrounding planets; but as this centre of gravity is generally within the body of the Sun, and can never be at the distance of more than the length of the solar diameter from the centre of that body, astronomers generally consider the Sun as the centre of the system, ‘round which all the planets revolve ; though in reality the centre of gravity of the Sun, and of all the planets, is the centre of the world. As the Sun revolves on an axis, his figure is supposed not to be strictly in the form of a globe, but a little flatted at the poles; and that his axis makes an angle of about eight degrees, with a perpendicular to the plane of the earth's orbit. . As the Sun's apparent diameter is longer in December than in June, it follows that the Sun is nearer to the earth in our winter than it is in summer; for the apparent magnitude of a distant body diminishes as the distance increases. The mean apparent diameter of the Sun is stated to be 32' 2"; hence, taking the distance of the Sun from the earth to be 95 millions of miles, as is now determined, its real diameter will be 886,149 miles; and, as the magnitudes of all spherical bodies are as the cubes of their diameters, the magnitude of the Sun will be 1,377,613 times that of the earth ; the diameter of the earth being 7964 miles, the diameter of the Sun is above 111 times the diameter of the earth. ... When we consider the Sun as the fountain of light that illuminates this universe, and that causes the earth to produce every thing desirable for man, may we not consider it also as an eminent, large, and lucid planet; evidently the primary one of our system; Mercury, Venus, the Earth, and all the others, being its secondaries 2 And consi- dering its solidity, its atmosphere and diversified surface, its rotation on its axis, and all the circumstances attending this glorious globe, may we not conclude that it is inhabited, like the other planets, by beings whose organs are adapted to the physical properties of the Sun. This seems to be a more pleas- ing and agreeable way of making the tour of creation; than joining issue with fanciful poets, who have pronounced it the abode of blessed spirits; or closing with the chilling doctrines of angry moralists, who have fancied it the fittest residence for the punishment or purgation of the wicked from off the earth. The PLANETS.–There are eleven planets belonging to our system. Six of these have been recognized from time imme- morial : namely, Mercury, Venus, the Earth, Mars, Jupiter, and Saturn. But the remaining five, invisible to the naked eye, have lately been discovered by the help of the telescope; and are therefore called telescopic planets: namely, Uranus, discovered by Dr. Herschel, March 13, 1781. Ceres. . . . . . we tº e º 'º e º e º 'º e s ºr M. Piazzi, ... January 1, 1801. Pallas. . . . . . . . . . . . . . . . . . . M. Olbers,.... March 28, 1802. Juno . . . . . . . . . . . . . . . . . . . ..M. Harding, Septem. 1, 1803. Vesta . . . . . . . . . . . . . . . . . . . . M. Olbers,.... March 29, 1807. All these Planets revolve round the sun, as the centre of motion; and in performing their revolutions they follow the laws of planetary motion discovered by Kepler, and confirmed by subsequent observations. These laws are, The orbit of each planet is an ellipse; of which the sun occupies one of the foci. That focus is called the lower focus. If we suppose the plane of the earth’s orbit, which passes through the centre of the sun, to be extended in every direction, as far as the fixed stars, it will mark out a great circle among them, which is the ecliptic; and with this the situations of the orbits of all the other planets are compared. The planes of the orbits of all the other Planets must necessarily pass through the centre of the sun, but if extended as far as the fixed stars, they form circles different from each other, as also from the ecliptic; one .* M. Cassini determined the time which the Sun takes to revolve on its axis, thus: the time in which a spot returns to the same situation on the Sun's disc, (determined from a series of accurate observations,) is 27 days 12 hours 20 minutes; now the mean motion of the earth in that time is 27° 7' 8" : hence 360° -- 27° 7' 8" ; 27d. 12h. 20 m. : : 360° : 25d. 14h. 4m. the time of rotation. ſºonoº. S. s -- & S aw ºf ºzoº/, / / /*/e. s - s º/” ſ/a/a/ of Z/e ///zzº. º' ºr ºn tº ſº. - s s - - º º A S T A S T 69 DICTIONARY OF MECHANICAL SCIENCE part of each orbit, is on the north, and the other on the south ººs ºs side of the ecliptic. Therefore , Ajšº the orbit of each planet cuts the Š º ecliptic in two opposite points, as A B, fig. 110, which are called the nodes of that particu- lar planet; and the nodes of one planet cut the ecliptic in planes different from the nodes of another planet. The line A B is called the line of the modes. The ascending node is that where the planet passes from the south to the north side of the eeliptic. The angle E G is the inclination of the planes of the two orbits to each other. The descending node, that where the planet passes from the north to the south side of the ecliptic. Perigee, when the sun and moon are nearest the earth ; apogee, when at their greatest distance. The extremity of the major axis of this ellipse, nearest the sun, is called the perihelion; the opposite extre- mity of the same axis is called the aphelion. The line, which joins these two points, is called the line of the apsides. The radius vector is an imaginary line drawn from the centre of the sun to the centre of the planet, in any part of its orbit. The velocity of a planet in its orbit is always greatest at its perihelion. This velocity diminishes as the radius vector increases, till the planet arrives at its aphelion, when its motion is the slowest. It then increases in an inverse manner, till the planet arrives again at its perihelion. The areas, described about the sun by the radius vector of the planet, are proportional to the times employed in describing them; and these laws are sufficient for determining the motion of the planets round the sun ; but it is necessary to know, for each of these planets, seven quantities; which are called the elements of their elliptical motion. The first five of these elements relate to the motion in an ellipse; the last two relate to the position of the orbit, since the planets do not all move in the same plane; agreeably to the following tables of La Place, calculated or the commencement of the present century. 1. Duration of the Sidereal Revolution. Days. Days. Mercury .......... 87-929-H | Ceres ....... . . . . . 1681:539-- CIlu S . . . . . . . . . . . . 224.700+ | Pallas . . . . . . . . . . . 1681-709-1- Earth . . . . . . . . . . . . 365256+ Jupiter. . . . . . . . . . 4332°569+ Mars. . . . . . . . . . . . . 386-979-H | Saturn . . . . . . . . . . 10758'969-1- Vesta . . . . . . . . . . . . 1335.205-H | Uranus. . . . . . . . . . 30689-712-1- Juno . . . . . . . . . . . . . 1590-998–H 2. The Mean Distance of the Planets from the Sun. Mercury . . . . . . . . . . . '3870381 Ceres............. 2.7674060 Venus . . . . . . . . . . . . . ‘7233323 Pallas. . . . . . . . . . . . 27675920 Earth . . . . . . . . . . . . . 1:0000000 || Jupiter . . . . . . . . . . . 5-202791 l Mars. . . . . . . . . . . . . . 1.5236935 | Saturn ....... . . . . . 9:5387705 Vesta... . . . . . . . . . . . 2.3730000 | Uranus .... . . . . . . . 19° 1833050 Juno . . . . . . . . . . . . . . 2-6671 630 || - 3. Ratio of the Eccentricity to Half the Major Apsis. Mercury ..... . . . . . 20551494 | Ceres . . . . . . . . . . . . •07834S60 Venus. . . . . . . . . . . . ‘00685298 || Pallas. . . . . . . . . . . . “24538400 Earth. . . . . . . . . . . . . •01685318 Jupiter. ... . . . . . . . . .04817840 Mars . . . . . . . . . . . . . •09322000 | Saturn . . . . . . . . . . . . .05616830 Vesta . . . . . . . . . . . . '09322000 | Uranus . . . . . . . . . . . *04667030 Juno . . . . . . . . . . . . . *25404400 4. Mean Longitude. Mercury. . . . . . . . . . 182° 15647 Ceres . . . . . . . . . . . . 2940 16820 Venus. . . . . . . . . . . . 11 93672 || Pallas ........... .280 68580 Earth . . . . . . . . . . . . 111 28179 || Jupiter .... . . . . . . . 124 67781 Mars . . . . . . . . . . . . . 71 24145 | Saturn ....... . . . . . 150 38010 Vesta . . . . . . . . . . . . 297 12990 | Uranus . . . . . . . . . . . 197 64244 Juno . . . . . . . . . . . . 322 7.9380 5. Mean Longitude of the Perihelion. Mercury . . . . . . . . . . 829 6256 || Ceres . . . . . . . . . . . . . . 1629 9565 Venus . . . . . . . . . . . . . 142 9077 | Pallas. . . . . . . . . . . . . 134 7040 Earth . . . . . . . . . . . . . . 1 10 5571 Jupiter . . . . . . . . . . . . 12 3812 Mars. . . . . . . . . . . . . . 369 3407 Saturn. . . . . . . . . . . . . 99 0549 Vesta . . . . . . . . . . . . . 277 4630 | Uranus ... . . . . . . . . . . 185 9574 Juno . . . . . . . . . . . . . . 59 2349 6. Longitude of the Ascending Node. Mercury. .......... 51° 0651 Ceres . . . . . . . . . . . . . . 899 9083 Venus ............. 83 1972 | Pallas . . . . . . . . . . . . . 191 7148 Earth . . . . . . . . . . . . . . 0 0000 || Jupiter. . . . . . . . . . . . 109 3624 Mars. . . . . . . . . . . . . . 53 3605 || Saturn . . . . . . . . . . . . 124 3662 Vesta .............. 114 4630 | Uranus. . . . . . . . . . . . 80 9488 Juno . . . . . . . . . . . . . . 190 1228 7. Inclination of the Orbit to the Ecliptic, Mercury ........... 7° 78058 || Ceres . . . . ... . . . . . . . 119 80680 Venus ............. 3 76936 | Pallas . . . . . . . . . . . . . 38 46540 Earth.............. 0 00000 || Jupiter . . . . . . . . . . . . 1 46034 Mars e . 2 05663 | Saturn...... . . . . . . . 2 77102 Vesta . . . . . . . . . . . . . 7 94010 | Uranus. . . . . . . . . . . . 0 85990 Juno. . . . . . . . . . . . . . 14 50860 The examination of the first two tables will shew us, that the duration of the revolutions of the planets increases with their mean distance from the sun. Whence Kepler discovered his third fundamental law ; namely, The squares of the times of the revolutions of the Planets are to each other as the cubes of their mean distances. But then the ellipses which the Planets describe, are not unalterable: their major axes are the same ; but their eccentricities, the positions of their perihelion nodes, with the inclination of their orbits to the ecliptic, seem to vary in a course of years. Mercury 3, the least of the inferior planets, and yet nearest to the sun, is 36,814,721 miles from that luminary. This planet emits a bright white light, and sometimes appears a little after sunset, and again a little before sunrise: but as this planet is So very near the sun, and of itself very small, we seldom see him without a telescope. As seen through a telescope, Mer- cury exhibits all the phenomena of the moon, which shews that it receives its light from the sun, as does our earth. The perio- dical revolution, mean distance from the sun, &c. of Mercury, are all given in the foregoing tables. The best observations of this planet are those made when it is seen on the sun’s disc or face, called the transit of Mercury. The last transit happened in 1822, and the intervals are very remote. The apparent diameter is about eleven seconds; hence the real diameter is . miles, or about one-sixteenth of the magnitude of the earth. Venus, 2, Fig. 111.—Venus, the next planet above Mercury, is computed to be sixty-eight millions of miles from the sun, $ and by moving at § | |\ | | | º the rate of seven- | | º \| | ty - six thousand 'ºï C |||} º ſº y | --> # --- g miles an hour, she completes her an- mual revolution in 224 days and 16 E- hours, 49' 11" and |}}}# a half, and her *— aſí synodical revolu- tion is about 548 days. Her diameter is seven thousand seven hundred miles, or nearly the size of our earth, and her diurnal rotation on her axis is performed in 23 hours 21 minutes and 7”. Venus is often seen by the unassisted eye in broad daylight. The pro- portion of light and heat received by this planet from the sun is 1.9l times greater than the earth. And it is surrounded with an atmosphere, the refractive powers of which differ very little from ours. Like Mercury, it sometimes passes over the sun’s face, and its transit has been applied to one of the most important problems in astronomy, as by it the true distances of the planets from the sun have been determined. These transits take place in the months of June and December. The first will be on the 8th December, 1874. When Venus is to the west of the sun, it rises before the sun, and is called a morning star; this appearance continues about 290 days together; when this planet is to the east of the sun, it sets after the sun, and is called an evening star for about the same period of 290 days. Venus appears the brightest of the planets; it has a consider- able atmosphere, and some astronomers assert, that they have discovered mountains on its surface. At times this planet appears gibbous like the moon, fig. 111. T --- º E= lº ºmiſiú ?0 A st A S T DICTIONARY OF MECHANICAL SCIENCE. The Earth, GB, fig. 112–The Earth which we inhabit is the planet next in order; hence we say, Mercury and Venus are inferior; but all the planets which are further from the sun than the Earth is, are superior planets. The Earth is 93 millions of miles from the sun; it performs its sidereaſ revolution in 365d 6h 9' 11" 5; and it passes from the one tropic, to the same again, in only 365d 5h 48' 51" 6. The axis of the Earth is inclined to the plane of the ecliptic in an angle of 23° 27' 57", and the points of intersection are called the equinoctial points; and the ecliptic is the path of the Earth in its annual revolu- tion round the sun. ... * There are several ways of shewing, that the Earth upon which we live is spherical, like an orange; and this is the form of all the planets. The shadows of bodies in general take the form of their originals. The shadow of the Earth on the moon, that is to say, an eclipse of the moon is, circular: the Earth is, therefore, globular. Several navigators, by sailing westward, have reached the port they first left. They must, therefore, have sailed round a globular surface. And they have observed, that on leaving land the shores first disappeared, then the hills. On the con- trary, approaching land, mountains are first seen, then the shores. These facts also corroborate our illustration of the Earth's sphericity. The Earth is supposed to be surrounded by various lines, that indicate portions of its surface, or enable us to perform the mechanical operations of Geography, Navi- gation, and Astronomy. The axis of the Earth is an imaginary line passing through its centre. Upon this line it is supposed Jºrg, LI2 C - - - - - - - - - - ----- - - - - -- distance from the Sun; C is the aphelion, or higher apsis, being its greatest distance ; and the distance between the Sun (in the focus) and the centre S, is called the eccentricity of the Earth's orbit. If from the centre there be erected upon the axis a perpendicular meeting the orbit in L, a point in the centre of the figure B, and the line F L be drawn, it will repre- sent the Earth's mean distance from the Sun, being equal to half the axis A C, consequently F L is 95 millions of miles. The phenomena of the different seasons of the year will ap- pear from the following observations:—Let A B C D represent the Earth's annual orbit, with the Sun in the focus F.; a b, an imaginary line through the Earth’s centre, perpendicular to this plane ; the axis NS, of the Earth, forming an angle of 23° 28′ to turn in its diurnal revolution. The poles of the Earth are the extremities of its axis. The lines or circles surrounding the Earth are of two names, great and small. All great circles divide the Earth into two equal portions; all small circles cut it in unequal parts. The equator is a great circle equidistant from both poles. The latitudes of places are reckoned north or south of the equator, as they lie on either side of that line. Meridians are great circles of the Earth, crossing the equator at right angles, and terminating in the poles. Parallels of lati- tude are less circles, drawn parallel to the equator. The longi- tude of a place is the distance of the meridian of that place, east or west, from the first meridian. As the Earth revolves round its axis daily from west to east, the heavenly bodies appear to a spectator on the Earth to revolve in the same time from east to west, and the alternate succession of day and night is the effect of the revolution of the Earth towards and from the sun. For all the heavenly bodies appearing to move from east to west, while the Earth revolves from west to east, the sun will appear, in each revolution, to rise above the horizon in the east, and after describing a portion of a circle, to set in the west, and will continue below the horizon, till, by the revolu- tion of the Earth, it again appears in the east: and thus day and night are alternately produced. • * The Sun is supposed to be fixed, not in the centre of the Earth's elliptical orbit, but in one of the foci. Let F represent the Sun, (fig. 112) and A B C D the Earth's elliptical orbit. Then A is the perihelion, or lower apsis, being the Earth's nearest with this perpendicular: then if the Earth move in A, B, C, D, so that N S may always remain parallel to itself, with the same angle to a b, it will denote the seasons; for, a line drawn from the Sun to the Earth, the Sun will be vertical to that part cut by this line. Now, when the Earth is in Libra ze, the Šunwill appear in Aries Yº, and we have Spring, the days and nights are equal in both hemispheres, and the season a medium between summer and winter; the line dividing the dark and light hemispheres, passes through the poles N and S, dividing all the parallels of latitude, as PR, equally; hence all the inhabitants of the Earth have their days and nights equal, viz. twelve hours each. While the Earth moves from Libra A to Capricorn wº, the north pole N will be more enlightened, and A S T 71 . DICTIONARY OF MECHANICAL SCIENCE. 'A s T * the south pole S more darkened; hence the days in the northern hemisphere will increase, and in the southern hemisphere decrease, the parallels of latitude being unequally divided. When the Earth has arrived at Capricorn Wºº, the Sun will appear in Cancer ge: this period is a medium between spring and autumn, and is called Summer in the northern hemisphere ; in the southern, winter then reigns; at the north pole, and within the arctic circle, there will be constant day; at the south pole, and within the antarctic circle, constant night. While the Earth moves from Capricorn Vſ to Aries on, the south pole will be more enlightened; consequently, the days in the southern hemisphere will increase, and decrease in the northern hemi- sphere. When the Earth has arrived at Aries on, the Sun will appear in Libra re, and the days and nights be again equal all over the Earth: this period is a medium between summer and winter, and is called Autumn. Again, as the Earth moves from Aries on towards Cancer ge, the light will gradually leave the north pole and proceed to the south: when the Earth has arrived at Cancer ge, it will be summer in the southern hemisphere, and winter in the northern: the south pole will have continual day, the north pole constant night; this period is a medium between autumn and spring, and is denominated Winter. Lastly, while the Earth moves from Cancer gº to Capricorn wº, the Sun will appear to move from Capricorn Vſ to Cancer ge, and the days in the northern hemisphere will increase, while those in the southern diminish ; and while the Earth moves from Capricorn w; to Cancer ge, the Sun will appear to move from Cancer gº to Capricorn V:9, the days in the northern hemi- sphere will decrease, and those in the southern increase. In all situations of the Earth, the equator will be divided equally ; consequently, the days and nights at the equator are always equal. Thus, the different seasons are clearly accounted for, by the inclination of the Earth's axis, the plane of its orbit combined with the parallel motion of that axis. The axis of the Earth, in its circuit round the sun, being inclined to the plane of its orbit, this inclination occasions the succession of the four seasons. The Earth's axis makes an angle of 66° 32' with its orbit, that is, with the ecliptic, and always preserves its parallelism, or is directed towards the same point in the heavens; hence during one half of the year the north pole is continually illuminated by the sun, and the south pole is all that time in darkness; and during the other half the year, the south pole is constantly in the light, and the north pole is in darkness; and other parts in a proportional degree partake of this vicissitude, and create the variety of the seasons. The difference in the degrees of heat, is owing chiefly to the different heights to which the sun rises, and the different lengths of the days. When the sun rises highest, in summer, its rays fall less obliquely, and consequently more of them fall on any given portion of the Earth's surface than in winter, when the rays fall obliquely; and when the days are long, and the nights short, the earth and air are more heated in the day than they are cooled in the night, and the reverse when the days are short and the nights, long. The lengthening and shortening of the days, and the different seasons, are produced by the motion of the Earth, NS, fig, 112, in its orbit round the sun, F. The axis of the Earth N S inclines to the plane of the orbit, and is parallel to itself in all parts of the orbit. In June the north pole N inclines to the sun, and it is summer in the northern parts of the earth ; in December the north pole declines from the sun, and it is winter in the northern and summer in the southern hemisphere. There are several ways of demonstrating that the planets move round the sun; thus, Mercury aud Venus always appear in the neighbourhood of the sun, and if the sun revolved round the Earth as a centre, so must these planets; but if they did, then the motion of each would always appear to us nearly equable, and in the same direction; whereas now they are sometimes stationary, or have no proper motion ; sometimes they move eastward in reference to the fixed, stars, and their motion is then called direct, progressive, or in consequentia ; sometimes they move westward, and have a retrograde motion, when they are said to move in antecedentia ; appearances which are necessary, when we admit the sun to be the centre of their orbits, and of the Earth's, but wholly irreconcileable with any other hypothesis. - . Moreover, when Mercury and Venus appear in conjunction with the sun, they are sometimes hid behind the body of the sun, and sometimes pass between it and the Earth, appearing like a dark spot on the sun's disc or face; but if they have lati- tude, when in their superior conjunction, that is, when beyond the sun, they shine with a face perfectly circular, like a full moon. But the face disappears in their inferior conjunction, that is, when between us and the sun, as the moon does at her change; whence it is evident, that their orbits are between the sun and the orbit of the Earth. Mars sometimes appears in opposition to the sun, which proves that its orbit includes that of the Earth; and that it includes the sun is plain, other- wise Mars would, in its conjunction with the sun, disappear, like Mercury and Venus, which never happens: the same may be observed of Jupiter, Saturn, and Herschel. The motions of the Earth in its orbit are proved, by the effect of its motion on the apparent motions of the several planetary bodies. These, as the Earth happens to be situated, become stationary, retro- grade, or direct, and the variations are exactly measured by motions referred to the Earth, like the motions of objects ashore, when we are moving in a boat. As the Earth revolves round the sun in 365 days, 6 hours, 56 minutes, 4 seconds, the sun appears to revolve round the Earth in the same time, but in the contrary direction. It is manifest, that the circle in which the sun appears to move, is the same in which the Earth would appear to move to a specta- tor in the sun. Hence the apparent place of the sun being found, the true place of the Earth in its orbit is known to be 1809 distant. The orbit in which the Earth revolves round the sun, fig. 112, is an ellipse, having the sun in one of its foci. For the computations of the sun's place, upon this supposition, allowing for the disturbing forces of the planets, are found to agree with observations. The circle which the sun appears to describe annually among the more distant fixed stars, is called the Ecliptic; and a portion of the heavens, about 16 degrees in breadth, through the middle of which the ecliptic is traced, is called the Zodiac, in which the orbits of all the planets are described by their respective revolutions. The stars round the Zodiac are classed in 12 signs: Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricorn, Aquarius, Pisces. Figures, representing these signs, are drawn in Dr. Jamieson's Celestial Atlas, and upon the Celestial Globe, in that portion of its spherical surface which corresponds to the portion of the concave sphere of the heavens in which the stars belonging to each sign are respectively found. Spring Signs. - Summer Signs. of Aries, the Ram, 21st March. 8 Taurus, the Bull, 19th April. II Gemini,the Twins,20th May. These are called Northern Sign Autumnal Signs. are Libra, the Balance, 23d September. m. Scorpio, the Scorpion, 23d October. ! Sagittarius, the Archer, 22d ge Cancer, the Crab, 21st June. SU Leo, the Lion, 22d July. my Virgo, the Virgin, 22d Aug. s, being north of the equinoctial. |Winter Signs. Vý Capricornus, the Goat, 21st December. ::: Aquarius, the Water-bearer, 20th January. × Pisces, the Fishes, 19th November. February. These are called southern signs. The spring and autumnal signs are called ascending signs ; because when the sun is in any of these, his declination is increasing. The summer and winter signs are called descending signs; because when the sun is in any of these, his declination is decreasing. The axis of the Earth in every part of the Earth's revolution about the sun, makes, with the plane of its orbit, that is, of the ecliptic, an angle of 663 degrees, consequently the planes of the equator and ecliptic make with each other an angle of 23; degrees nearly, being the complement of 90 degrees. The obliquity of the ecliptic is not permanent, but is continually diminishing by the ecliptic approaching nearer to a parallelism with the ºquatºr, at the rate of about half a second in a year, or from 50" to 55" in 100 years. The inclination at this time is 23° 27' 46" nearly. The diminution of the obliquity of the ecliptic to the equator, is owing to the action of the planets upon the earth, especially the planets Venus and Jupiter. The whole diminution, it is said, can never exceed one degree, | when it will again increase. The diminution of the obliquity of 72 A S T A. S. T. DICTIONARY OF MECHANICAL SCIENCE. the ecliptic is a consequence of the approach of the Earth's axis towards a perpendicular direction to the plane of the ecliptic; but the Earth's axis has, besides the progressive motion, a tremulous one, by which its inclination to the plane of the ecliptic varies backwards and forwards some seconds: the period of these variations is nine years. The tremulous motion is termed the mutation of the Earth's axis. Both these motions of the terrestrial axis are occasioned by the action of the sun, moon, and planets on the earth. There are several other astronomical phenomena, that belong to these scientific views of the Earth; but we will give them in their proper places, rather than encumber this article with what is more detached. The Moon, the Earth's satellite, has motions eccentric and irre- gular. She performs her sidereal revolution in 27d 7h 43' 11",5 But this period is variable, and on comparison of the modern observations with the ancients, proves incontestably an accelera- tion in her mean motion. Her mean tropical revolution is 27d 7h 43'4",7; and her mean synodical revolution is 49a 12h 42'2",8. Her mean distance from the earth is 29-98.2175 times the diameter of the terrestrial equator; or above 237,000 miles. Her orbit is inclined to the plane of the ecliptic in an angle of 5°9'; but this inclination is variable. The greatest inequality, which sometimes extends to 8'47", 1, is proportional to the co-sine of the angle on which the inequality of the nodes depends. Her orbit, at the commencement of the present century, crossed the ecliptic in 0s 15° 55' 26",3; but the place of her modes is variable. They have a retrograde motion, and make a sidereal revolution in about 18:6 Julian years. A synodical revolution of the nodes is performed in 346d 14h 52'43",6. The motion of the nodes is subject also to a secular inequality, dependent on the acceleration of the Moon's mean motion. The rotation of the Moon on her axis is equal and uniform; and it is performed in the same time as the tropical revolution in her orbit, whence she always presents nearly the same face to the earth. But, as the motion of the Moon in her orbit is periodically variable, we sometimes see more of her eastern edge, and sometimes more of her western edge. This appearance is called the libra- tion of the Moon in longitude. The axis of the Moon is inclined to the plane of the ecliptic in an angle of 88°29'49". In conse- quence of this position of the Moon, her poles alternately become visible to, and obscured from us: and this phenomenon is called her libration in latitude. There is also another optical deception, arising from the Moon being seen from the surface of the earth, instead of the centre. This appearance is called her diurnal libration. The figure of the Moon A, B, C, &c. (fig. 113,) is that of an oblate spheroid like the earth T. Her mean diameter is in the proportion to that of the earth, as 5823 to 21832; or, as 1 to 3:665. Whence her mean diameter will be about 2160 miles. But the apparent diameter of the Moon varies according to her distance from the earth. When nearest to us, it is 33' 31", 1 ; and at her greatest distance it is 29'21",5. Hence her mean apparent diameter is 31'26",5. The different phases of the Moon constitute some of the most striking phenomena of the heavens. When she emerges from the sun’s rays, S, in the even- ing, she appears as a small crescent, b, just visible; but as she separates from the sun this crescent increases, c, d, till in oppo- sition, e, when the moon is completely illuminated. This circle changes reversely into a crescent, f, g, h, till the Moon has plunged into the sun's rays in the morning at sun-rise. And the crescent being always directed to the sun, indicates that the Moon is herself a dark opaque body, borrowing her light from the sun. These different phases, A, B, C, D, &c. of the Moon are renewed after every conjunction; and the points of the lunar orbit, in which the Moon is either in conjunction or opposition to the sun, are called the syzygies. In the first point, the Moon is new, in the second full; in her first quarter the Moon is 90° from the first point; in her third quarter 270° from the same point. Mars, 3, fig. 114–Mars first above the earth's orbit is easily known by his red and fiery appearance. He performs his side- real revolution in 686d 23h 30' 39", or in 1881 Julian year; and his mean synodical revolution is about 780 days, or in about 2-135 years. His mean distance from the sun is above 142 millions of miles. The rotation on his axis is performed in ld Oh 39'21",3; and his mean diameter is 4398 miles, or rather Millſº | MIT n-ore than One half C. | | | | | o - = "| º = \| the size of our earth. This planet has a | very dense but mo- | derate atmosphere, | and he is not attend- | ed by any satellite. - And the proportion |h of light and heat re- - - ceived by him from the sun is 43, that received by the earth being considered as unity. Mars changes his phases in the same manner as the moon does, from her first to her third quarter, according to his various positions with respect to the earth and sun, Vesta tº . This planet was discovered by Dr.Olbers, of Bre- men, on the 29th of March, 1807; its distance from the sun is 225,485,000 miles, and the length of its year, 3 years 240 days 5 hours. Vesta appears like a star of the fifth magnitude. Juno fºuno was discovered by Mr. Harding, of Lilienthal, in the duchy of Bremen, on the first of September, 1804. It appears like a star of the eighth magnitude: its distance from the sun is 253,380,485 miles, and its periodical revolution is performed in 4 years and 131 days. Ceres 2 –Ceres was discovered by M. Piazzi, astronomer royal, at Palermo, in the island of Sicily, on the 1st of January, 1801. The length of its year is 4 years 221 days 13 hours; its distance from the sun is 262,903,570 miles, and its diameter, *cording to Dr. Herschel, is about 162 miles. Ceres appears like a star of the eighth magnitude. Pallas & was discovered by Olbers on the 28th of March, 1802. Its distance from the sun is 253,000,000 miles. Its annual revolution is completed in about 4 years 7 months and 10 days. Like the two former newly discovered planets, its diameter and diurnal rotation are as yet unknown. Jupiter, nº fig, 116, is about four hundred and eighty-five millions of miles from the sun. It completes its annual revolu- tion in about 12 years, moving at the rate of 29,000 miles an hour. Its diameter is 91,500 miles, yet by an exceedingly rapid motion upon its axis, the diurnal rotation is performed in nine hours and 55 minutes : Notwithstanding the great distance of this fine planet from the sun and the earth, it appears, to the naked eye, almost as large as Venus, though with a less brilliant light. | When Jupiter rises as the sun sets, and sets as the sun rises, it comes to the meridian at midnight, and ap- pears larger and more luminous that at other times. It is a morning | | A. S. T. A. S. T. 73 DICTIONARY OF MECHANICAL SCIENCE. star when its longitude is less than that of the sun, and an evening star when the longitude is greater than that of the sun. Jupiter is surrounded by faint substances, called zones or belts, which, from their frequent change in number and situa- tion, are generally supposed to consist of clouds. One or more dark spots frequently appear between the belts; and when a belt disappears, the contiguous spots disappear likewise. The time of the rotation of the different spots is variable, being less by six minutes near the equator than near the poles. Satellites of Jupiter.—By the aid of the telescope we may discover four satellites revolving round Jupiter. The side- real revolutions of these bodies are given in the following table: together with their mean distances from Jupiter, the semidiameter of that planet's equator being considered as unity; and likewise their masses, compared with Jupiter, considered also as unity. Table. Satellite Sidereal Revolution Mean Mass - - Distance. - I. 1d 18h 27° 33',5 : 10769137788148) 5-812964|-0000173281 II. 3 13 13 42 0 || 3 551.181017849) 9:248679-0000232355 III. 7 3 42 33 4 || 7 154552783970.14752.401-0000884972 IV. 16 16 31 49 ,7|16 6887697.0708425-946860-0000426591 The satellites of Jupiter are liable to be eclipsed by passing through his shadow; and on the other hand, they are frequently seen to pass over his disk, and eclipse a portion of his surface. This happens to the first and second satellite at every revolu- tion; the third very rarely escapes in each revolution; but the fourth (on account of its great distance and inclination) is seldom obscured. These eclipses are of great utility, in enabling us to determine the longitude of places, by their observation; and they likewise exhibit some curious pheno- mena with respect to light. From the singular analogy above alluded to, it follows, that, (for a great number of years at least,) the first three satellites cannot be eclipsed at the same time: for in the simultaneous eclipses of the second and third, the first will always be in conjunction with Jupiter, and vice versa. Saturn, P., fig. 117-Saturn is about eight hundred and ninety millions of miles from the sun. It moves at the rate of 22,000 miles an hour, and performs its annual revolution in a little less than 294 years. His mean distance from the sun is above 890 millions of miles. The rotation on its axis is per- formed in 10h 16, 19",2; and the axis is inclined in an angle of 58° 41' to the plane of the ecliptic. His mean diameter is 76068 miles; consequently he is nearly ten times as large as our earth. The axis of his poles is to his equatorial diameter as 11 to 12. The proportion of light and heat received from the sun is 0011; that received by the earth being considered as unity. Saturn is sometimes marked by zones or belts, which are probably obscurations in his atmosphere; and he is | -- li -- |-- ||| accompanied by seven satellites. The most singular pheno- menon, however, attending this planet, is the double ring with which he is surrounded. This ring, which is very thin and broad, is inclined to the plane of the ecliptic in an angle of 31°19' 12",0; and revolves from west to east, in a period of 10h 29' 16",8, about an axis perpendicular to its plane, and passing through the centre of the planet. The breadth of the ring is nearly equal to its distance from the surface of Saturn; that is, about one-third of the diameter of the planet. The surface of the ring is separated in the middle by a black con- centric band, which divides it into two distinct rings. The edge of this ring, being very thin, sometimes disappears; and, as this edge will present itself to the sun twice in each revolu- tion of the planet, it is obvious that the disappearance of the ring will occur about once in 15 years, but under circumstances oftentimes very different. The intersection of the ring and the ecliptic is in 5s 20° and 11s 20°; consequently, when Saturn is in either of those signs, his ring will be invisible to us. On the contrary, when he is in 2s 20° or 8s 20°, we may see it to most advantage. This was the case towards the end of the year 1811. Satellites of Saturn.-Seven satellites may be seen, by means of the telescope, to revolve about Saturn; the elements of which are but little known, on account of their great distance. The following table will shew the duration of their sidereal revolutions, and their mean distances in semidiameters of Saturn. Satellite. Sidereal Revolution. Mean Distance. I. Od 22h 37' 30", 1 0d 9427.1 3-080 II. 1 8 53 8 ,7 I 37024 3-952 III. 1 21 18 25 9 I 88780 4'893 IV. 2 17 44 51 , || 2 73948 6:268 V. 4 12 25 | 1 , || 4 51749 8-754, VI. 15 22 41 13 9 15.94530 20-295 VII. 79 7 54 37 4 || 79 32960 59-154 The orbit of the first six satellites appear to be in the plane of Saturn's ring; whilst the seventh varies from it very sensibly. Uranus, or Herschel, II, called also Georgium Sidus, was dis- covered by Dr. Herschel on the 13th of March, 1781. Its dis- tance from the sun is about one thousand eight hundred mil- lions of miles, and its diameter 35,000. Its annual revolution is completed in about eighty-four years, and its rotary motion in about the same time as Saturn. The appearance of Uranus is that of a star of the sixth magnitude, and therefore it can scarcely be seen without a telescope. The intensity of light or heat, on this distant planet, is to that on the earth as 276 is to 100,000. And the sun's diameter, as seen from Uranus, is about the magnitude of Jupiter's when in opposition. Satellites of Uranus.-Six satellites revolve round Uranus; which, together with their primary, can be discovered only by the telescope. The following table will shew their sidereal revolutions, and mean distances in semidiameters of the primary. Satellite, Sidereal Revolution. Mean Distance I. 5d 24h 25' 20",6 5d 8926 13-120 II. 8 16 57 47 ,5 8 7068 17022 III. 10 23 3 59 .0 | 10 9611 19845 IV. 13 10 56 29 ,8 13 4559 22-752 V. 38 1. 48 0 ,0 38 0750 45-507 VI. 107 16 39 56 , 2 | 407 6944 91*008 All these satellites move in a plane, which is nearly perpen- dicular to the plane of the planet's orbit, and contrary to the order of the signs. Of Comets.-Comets are opaque and solid bodies. A Comet, at a given distance from the earth, shines much brighter when it is on the same side of the earth with the sun, than when it is on the contrary side; from whence it appears, that it owes its brightness to the sun. Of all the comets, the periods of only three are known with any degree of certainty. The first of these Comets appeared in the years 1531, 1607, and 1682; and is expected to appear every 75th year. The second of them appeared in 1532 and 1661, and was expected to return in 1789, and every 129th year afterwards. The third having last appeared in 1680, and its period being no less than 575 years, U 74 A S T A S T - DICTIONARY OF MECHANICAL SCIENCE. cannot returnºuntil the year 2225. This Comet, at its greatest distance, is about eleven thousand two hundred millions of miles from the sun; and at its least distance from the sun's centre, which is 49,000 miles, is within less than a third part of the sun’s semidiameter from his surface. In that part of its orbit which is nearest the sun, it moves at the rate of 880,000 miles in an hour. The Chinese astronomers record the ap- pearance of about 300 Comets. The tail of the Comet of 1680 was at least 100 millions of miles long ; and that of 1812 was 30 millions of miles. The Comets trace, around the sun, very elongated ellipses, which degenerate into parabolae. Hence their appearance in our heavens is only momentary, because we can see them in only so small a portion of the curve they describe, though for some it extends to the confines of the solar system. This motion is without fixed direction; the Comets re-act every way, and frequent perturbations make their course devious. Such effect did the re-action of Saturn and Jupiter produce on the comet of 1759. By the action of Jupiter, that of 1770 deviated so much when towards its perihelion, that its orbit became elliptic. On its return, the same effect in a contrary direction caused it to resume its parabolic course. The cause of this luminosity, called the tail of a Comet, has been thus described :- “Suppose a globe of water, with an opaque ball in its centre—in other words, the pellucid atmosphere of a comet and its nucleus—suppose them placed in the sunshine (the situa- tion of a Comet at all times,) is it not then evident that the globe of water, with its opaque ball, would, by the refraction and reflection of rays of light, exhibit all the phenomena of a Comet's tail, under all the circumstances and variations of that tail? By the ordinary laws of refraction, the tail would be lengthened as it approached the sun, and would shorten as it receded, which we know accords with the phenomena. “The tail of a Comet is thence considered a grand optical exhibition of the phenomena of light. As the solar rays pass in their ordinary course through the medium of space, they exhibit no peculiar appearances; but when they impinge on the atmosphere of a planetary body, they undergo refractions and reflections ; then they exhibit their general, visual pheno- mena, whether it be as condensed in the shape of a Comet’s tail, or in giving luminosity to the figure of a planet. As the spherical refracting medium approaches the source of light, the foci of convergency of course are extended, and the quantity of light is increased ; and then is the Comet's tail of the largest dimensions, and the most luminous. As it recedes from the fountain of light, the foci draw nearer to the Comet, and the tail shortens ; at length the Comet recedes so far from the sun, that the quantity of light ceases to produce the same visual effect, while the increased distance from the earth combines also to render it altogether invisible. “Telescopes destroy the tail, because they magnify the space without increasing the light, an effect which is universal when they are applied to luminous objects, but more sensible in regard to a Comet’s tail than to any other object of telescopic observation; serving, therefore, to prove that it is light itself, rather than any crude vapour on which-light is impinging. The stars are seen through it, because they shine by their inherent light, and there is no substance or opacity intercepting their rays. “Supposing that fluids and solids compose nearly equal parts of Comets, it will not be difficult to explain their varied aspect. The sun's expansive action being null in its aphelion, it exhibits properties analogous to opaque bodies, but less marked, the fluids being adequate to produce a proper light. In this state, the Comet has a solid and opaque nucleus; pro- portionally greater, from the aqueous vapours condensed from its atmospheres; which last is of a moderate extent. “How pleasing is the idea of contemplating these travelling worlds, peopled with observers, employed in contemplating the universe at large, as we are busied in that of an insignifi- cant atom of it; passing from one sun to another, observing the orbits of the celestial spheres; viewing their particular and general revolutions; over their heads thousands of years rolling, merely as thousands of days over ours I” For the laws by which the planets are kept in their respec- tive positions, or whirled with unerring precision round the | others. sun, and amongst one another, see the articles ATTRACTION and LAws of PLANETARY MOTION. - . The Fiaced Stars.-Besides the sun, planets, and comets which we have noticed, as belonging to our system, there are other phenomena that we may observe, as the Fixed Stars, dis- tinguished from the planets, by being less bright, less luminous, and exhibiting continually an appearance, which we call the twinkling of the stars. The Fixed Stars are so named from their never changing their situation with regard to each other, as the planets change their places. They are, thence, considered suns of other systems or worlds. How magnificent then is this universe 1 - 1. The Fixed Stars are luminous bodies. Because they appear as points of small magnitude when viewed through a telescope, they must be at such immense distances as to be invisible to the naked eye, if they borrowed their light; as is the case with respect to the satellites of Jupiter and Saturn, although they appear of very distinguishable magnitude through a telescope. Besides, from the weakness of reflected light, there can be no doubt but that the Fixed Stars shine with their own light. They are easily known from the planets by their twinkling. - 2. The number of Stars, visible at any one time to the naked eye, is about 1000; but Dr. Herschel, by his skilful improve- ments of the reflecting telescope, has discovered that the whole number is great beyond all conception. The comparative brightness of the Stars is, Sirius 100, Canopus '98, Centauri 96, Achermar '94. 3. The magnitudes of the Fixed Stars appear to be different from one another, which difference may arise either from a diversity in the real magnitudes, or distances; or from both these causes acting conjointly. The difference in the apparent magnitude of the Stars is such as to admit of their being divided into six classes, the largest being called Stars of the first mag- nitude, and the least which are visible to the naked eye, Stars of the sixth magnitude. Stars only visible by the help of glasses are called telescopic Stars. Bode's catalogue contains . 17,000 Stars. Dr. Halley very justly remarks, that the Stars must be infinite in number, to maintain their equilibrium in space. And Dr. Herschel thinks he has seen Stars 42,000 times as far off as Sirius. In one instance, a cluster of 5000 stars, in a mass, were barely visible in the 40-foot telescope, and consequently must have been 11 trillions of miles off! 4. It must not be inferred, that all the Stars of each class appear exactly of the same magnitude, there being great lati- tude given in this respect; even those of the first magnitude appear almost all different in lustre and size. There are also other Stars of intermediate magnitudes, which, as astronomers cannot refer to any one class, they, therefore, place them between two; or that, in place of six magnitudes, there are probably as many different magnitudes as there are Stars. 5. To the naked eye, the Stars appear of some sensible magnitude, owing to the glare of light arising from num- berless reflections of rays coming to the eye; this leads us to imagine, that the Stars are much larger than they would appear, if we saw them only by the few rays which come directly from them, and entered the eye without being intermixed with Examine a Fixed Star of the first magnitude, through a long and narrow tube, which, though it takes in as much of the sky as would hold a thousand such stars, scarcely renders that one visible. Even our best telescopes do not enlarge these gems; and there seems but little reason to expect, that the real magnitudes of the Fixed Stars will ever be discovered with certainty; we must, therefore, be contented with an approxi- mation, deduced from their parallax, and the quantity of light they afford us compared with the sun. To this purpose, Dr. Herschel, with a magnifying power of 6450, and by means of his new micrometer, found the apparent diameter of a Lyrae to be 0°-335, or the third of a second. The ingenious observations of Kepler upon the magnitudes and distances of the Fixed Stars, have been followed by Dr. Halley. He observes, that there can be only 13 points upon the surface of a sphere as far distant from each other as from the centre; and supposing the nearest Fixed Stars to be as far from each other as from the sun, he concludes, that there can be only 13 Stars of the first magnitude. Henee, at twice that A T A A T R. DICTIONARY OF MECHANICAL scIENCE. 75 distance from the sun, there may be placed four times as many, or 52; at three times that distance, nine times as many, or 117; and so on. These numbers will give pretty nearly the number of stars of the first, second, third, &c. magnitudes. Dr. Halley farther remarks, that if the number of Stars be finite, and occupy only a part of space, the outward stars would be continually attracted to those within, and in time would unite into one. But if the number be infinite, and they occupy an infinite space, all the parts would be nearly in equi- librio, and consequently, each Fixed Star being drawn in oppo- site directions, would keep its place, or move on till it had found an equilibrium. Č A Constellation is a number of Fixed Stars, lying in the neighbourhood of each other, which astronomers, for the sake of remembering with more ease, suppose to be circumscribed by the outline of some animal or other figure. See ConstELLATION. An Eclipse of the Sun is caused by the moon passing between the sun and the earth; and an Eclipse of the Moon is the effect of the earth passing between the sun and moon. See ECLIPse. ASTROSCOPE, an astronomical instrument, composed of two cones, on whose surfaces are exhibited the stars and con- stellations, by means of which they are both easily found in the heavens. This instrument was the invention of Schukhard, professor of mathematics at Tubingen, who published a trea- tise expressly on it in 1698. tº e ASTROSCOPIA, is the art of observing and examining the stars with the telescope, in order to discover their nature and properties. - ASTROTHESIA, an ancient term, nearly synonymous with constellation. ASTRUM, or AstroN, a constellation or assemblage of stars, the same as Aster denotes a single star. ASYLUM, a sanctuary, or place of refuge, where criminals shelter themselves from the hands of justice. The asyla of altars, temples, tombs, statues, &c. is very ancient. The Jews had six cities of refuge, the temple and the altar of burnt-offer- ing. The temple of Diana, at Ephesus, was a refuge for debtors; hence, when the apostle of our Lord preached salvation to the worst of mankind, it included also the hapless debtor, who would thus be restored to the favour of the Deity; an idea in no ways compatible with the notions of the heathen creditor.— The emperors Honorius and Theodosius granting particular immunities to churches, the bishops and monks laid hold of a certain tract or territory, without which they fixed the bounds of the secular jurisdiction; and so well did they manage their privileges, that convents, in a little time, became next akin to fortresses, where the most notorious villains were in safety, and braved the power of the magistrate. g ASYMETRY, without measure, a want of proportion between the parts of a thing, as between the side and diagonal of a square, which are to each other as 1 : N/2. - ASYMPTOTE, incoincident, is properly a right line, which approaches continually nearer to some eurve, whose asymptote it is said to be, in such sort, that when they are both indefinitely produced, they are nearer together than by any assignable finite distance; or it may otherwise be considered as a tangent to the curve, when infinitely produced, or at an infinite distance. Two curves are also said to be asymptotical, when they thus continually approach indefinitely to a coincidence: thus two parabolas placed with their axis in the same right line, are asymptotes to each other. Of lines of the second kind, or curves of the first kind, that is, the conic sections, only the hyperbola has asymptotes, which are two in number. All curves of the second kind have at least one asymptote, but they may have three; and all curves of the third kind may have four asymptotes, and so on. The conchoid, cissoid, and loga- rithmic curve, though not geometrical curves, have each one asymptote; and the branch or leg of the curve that has an asymptote, is said to be of the hyperbolic kind. The nature of an asymptote is very difficult to be conceived by persons who are not acquainted with the higher geometry: they cannot comprehend how two lines should always continually approach each other, without the possibility of touching or coinciding; this mystery, however, may be elucidated, and the nature of these lines readily comprehended, by considering the genera- tion of the conchoid of Nicomedes, which is as follows. Let FK (fig. 118.) be any line in- definite towards K, and from the point P let there be drawn the lines PA, PB, PC, P D, &c. making the several parts FA, G. B., H C, ID, KE, &c. all equal to each other : the curve A B C D E, &c. passing through all the extremities A, B, C, D, &c. is called the con- choid of Nicomedes; and the line F K produced, is the P asymptote of the curve; and which, it is obvious from the construction, can never coincide or touch the curve itself, although the latter continually approaches towards the former. ATAR OF Roses, a precious essence,which is easily obtained, provided the material from which it is extracted is supplied in quantities sufficient for the purpose, but unfortunately one hundred weight of roses generally yields but from two to three ounces of Atar. The roses, with their calyxes, are to be immersed in double their weight of water, and distilled by a very gentle heat, from which will be obtained a very strongly scented rose wine. This must be cooled as quickly as possible by the night air, and the globular particles found upon its sur- face, carefully gathered the next morning, which are more or less abundant, according to the perfection of the roses. A peculiarly fragrant grass is employed in Persia along with the roses, besides other odorous vegetable substances which that rich climate produces; but although the quantity of essence is thereby increased, its quality is deteriorated. Even after the Atar has been gathered, the rose-water that remains is power- fully scented. It is not necessary to distil the roses immedi- ately after they have been gathered, as that may be incon- venient, particularly on account of the heat of the weather when the flower is produced. , Rose leaves, as well, as other flowers capable of affording fragrant essential oils, may be preserved for a long period, as in a pot-pourie, without losing any of their odour, or by being well rubbed, and mixed into a paste with common salt. The quantity of oil and water is said to be greatly increased by the salting process, which is indeed probable. The proportion of salt is one pound to three pounds of leaves. The flowers being bruised by the friction of the grains of salt, form a paste, which should be preserved in an earthen jar or barrel; continuing the process uniformly until the barrel or jar is filled, which may be kept in a cool place for several years, without impairing its flavour or strength. This aromatic paste may be distilled at any season of the year, mixing it with about twice its weight of water before you put it into the still. Indeed, in many gardens in Britain a sufficient quantity of rose leaves might be gathered in a couple of years, to verify this recipe for the extraction of Atar of roses. The generality of perfumes are made up of musk, civet, ambergris, cedar, roses, orange flowers, jonquils, jessamines, tuberoses, and other odoriferous flowers and plants; and their use among the Hebrews, and most of the Oriental nations, was common, before they were known to the Greeks and Romans. But as the nervous system is very much affected by the use of these völatile drugs, medical men generally strongly condemn the practice, still so much in fashion, of scenting the clothes, hands, face, &c. with musk, atar of roses, &c. - - ATARGATIS, a goddess of the Syrians, represented with the head and breasts of a woman, and the tail of a fish. Both the Syrians and Egyptians abstained from eating fish, which they seem to have held in singular dread and abhorrence, and when the Egyptians had to represent any thing as odious, or to express hatred by hieroglyphics, they painted a fish. A deity of the name of Dagon was worshipped under the form of a monster, which had the head and arms of a man, and the tail of a fish. This appears to have been the symbol of the sun in Pisces, and was considered as the principle of fecundity; hence Dagon seems to have been employed to signify the “corn and fruits of the earth.” No sign appears to have been considered of more malignant influence than Pisces. The astrological calendar describes the emblems accompanying 76 A T T A T T DICTIONARY OF MECHANICAL SCIENCE. this constellation as chiefly indicative of violence and death; yet the month of February, when the sun was in Pisces, was called Adar; perhaps in honour of the moon, which was adored by the title Adra-Daga, or the, “glorious fish.” ATCHIEVEMENT, or Achievement, in Heraldry, the arms of a person or family, marshalled in order; with quarterings by alliance, mottos, scrolls, crest, mantle, helmet, &c. ATHAMANTA, spignel. . ATHANASIA, goldilocks. - ATHANASIAN CREED, the exposition of faith composed by Hilary, bishop of Arles, about the year 430, and which was received at Rome about the year 1014, as a summary of the orthodox faith, and a condemnation of all heresies. ATHWART, in Navigation, across the line of the course ; athwart the forefoot, the direction of a cannon ball from one ship across another, to intercept the latter, and oblige her to shorten sail, and heave to, that the former may come near enough and examine her. Athwart hause, the situation of a ship when she is driven by wind or tide, or any other accident, across the fore part of another ship. * ATLAS, in matters of literature, a book of maps, either celestial, as Dr. Jamieson's atlas; or terrestrial, as Arrow- Smith’s atlas. ATRIPLEX, orach, or arach. ATROPA, deadly nightshade, whose horrid black berries and root are the rankest poisons. ATTACHMENT, in Law, the apprehending of a person by virtue of a writ. An attachment is issued out of a higher court than a writ, and may lie against the body and goods. |ATTAINDER, in Law, the immediate inseparable conse- quence of sentence of death being pronounced upon a criminal: or when a person flees from justice, which is tacitly confessing his guilt, the judgment of outlawry is the attainder, for the person is stained, attinctus, or blackened, by his own act. ATTITUDE, in Painting and Sculpture, the gesture of a figure or statue; or such a disposition of their parts as serves to express the action and sentiments of the person represented. ATTORNEY AT LAw, one put in the place of another per- son, to manage his matters in law. The attorneys are a regular corps, admitted to the execution of their duties § the superior courts of Westminster Hall, and are in all points officers of the respective courts into which they are admitted. The Attorney-general, a great officer appointed by the king's letters patent, prosecutes for the crown in matters criminal. His proper place in court is under the judges, on the left of their clerk: usually, however, he sits within the bar in front of the Court. - ATTRACTION, the tendency which all bodies have to approach each other, is distinguished into the attraction of cohesiom, and the attraction of gravitation. The attraction of cohesion takes place between bodies, only when they are at very small distances from each other. By this attraction, pos- sessed by the minute parts of matter, bodies preserve their form, and are prevented from falling to pieces. To prove the attraction of cohesion, take two pieces of lead with flat sur- faces; scrape them clean with a knife, squeeze them together, and they will adhere so firmly as to be separated with difficulty. And if you wet two bits of glass with water, they also will adhere firmly. Two globules of quicksilver placed near each other, will run together, and become one drop or ball. A Table of cohesive Powers of different Solids.--To estimate the absolute cohesion of solid bodies, Professor Musschen- broeck, applied weights to separate them according to their length. . The pieces of wood he used were parallelopipedons, whose side was ºths of an inch. The metal wires used were loth of a Rhinland inch in diameter. They were drawn asunder by the following weights: lbs. lbs. Fir ..... tº º ſº e º & tº e º ſº tº e 100 Copper. . . . . . . . . . . . 2994 Elm . . . . . . . . . . . . . . . . 950 Brass ... . . . . . . . . . . . 360 Alder . . . . . . . . . . . . . . . 1000 Gold . . . . . . . . . . . . . . 500 Oak. . . . . . . . . . . . . . . . . 1150 Iron . . . . . . . . . . . . . . 450 Beech...... . . . . . . . . . 1250 Silver . . . . . . . . . . . . . 370 Ash. . . . . . . . . . . . . . . . 1250 | Tin . . . . . ........... 49% Lead e e e º u a c e s tº Q te 29} law of hydraulics. Capillary Attraction—is accounted a species of cohesion. It is called capillary, from the tubes which draw the water above . its level being small as hairs. And the suspension of fluids in capillary tubes is owing to the attraction of the ring contiguous to the upper surface of the fluid. The height to which the fluid rises is inversely as the diameter of the bore. Experi- ments: Take a small glass tube open at both ends, dip it in water, and the water will rise in the tube higher than its level in the basin: the water will rise the higher, the smaller the bore of the tube is. Take two pieces of glass, five or six inches' square, join any two of their sides, separate the opposite sides with a small piece of wood, so that the surface may form a small opening, and immerse them about an inch deep in a basin of coloured water: then the water will rise between the glasses, and form a very beautiful curve. Upon the same principle it is that a piece of sugar, or a sponge, draws up water or any other fluid. All vegetables are but bundles of capillary tubes; and whether we consider earth, water, salt, and oil, as the food of plants, that food must be formed by water into an emulsion, capable of being acted upon by capillary attraction ; unless we suppose the juice, or food, to rise in those tubes by some As all the roots are but assemblages of these tubes, there can be little doubt but their attraction sup- plies the plant or tree with its first food; though other causes, no doubt, assist in carrying it to the tops of the tallest trees, such as dilatation and contraction, by the successive heat and cold of day and night; the muscular action of vascular rings round the tubes, irritated to contraction by the stimulant sap, &c. The interior bark conducts the nourishment supplied by the earth. Leaves on one side draw nutrition also from the air, and perspire on the other; light probably does the rest. It is probably owing to the various degrees of cohesion, that some bodies are hard and others soft; that some are in a solid, others in a fluid state. For when attraction prevails in bodies, they become solid; when fire prevails, they become gas; hence fluidity seems a medium between both. As it is by the attrac- tion of cohesion that the parts of bodies are kept together, this attraction is overcome when a body is broken. Hence the reason of soldering metals, gluing wood, &c. Hence, also, when the particles, or moleculae, of which a body is composed, so adhere the one to the other, that they cannot be separated without effort, we say of such a body that it is solid;—such are metals, stone, wood, &c. Hence, also, such substances as are composed of particles adhering very slightly, and which, yield- ing to any small effort, are easily moved among each other, we term fluids, such as water, beer, air, &c. These properties may result from the different figures of the particles, and the greater or less degree of attraction thereupon. Elasticity may arise from the particles of a body, when distended, not being amply drawn into each other’s attraction ; as soon, therefore, as the force which acts upon it ceases, they restore themselves to their former position. Density, strictly speaking, denotes the closeness of particles, and we use, the word here as a term of comparison, expressing the proportion or quantity of matter in one body, to the quantity in another. Repulsion is a force supposed to extend to a small distance round bodies, and prevent them from coming in actual contact. The repel- ling force of the particles of a fluid is small, and therefore, if a fluid be divided, it readily unites again. But if a hard sub- stance be broken, the parts cannot be made to adhere, unless they be moistened or melted according to their nature. Water repels most bodies till they are wet. A small sewing needle will swim in a basin of water. Drops of water will roll on the leaves of many vegetables without wetting them. If a ball of light wood be dipped in oil, and afterwards dropped into water, the water will be repelled from the wood, and will form a channel round it. ensity, therefore, is directly as the quan- tity of matter, and inversely as the magnitude of the body. The Attraction of Gravitation.—Gravity is that force by which all the masses of matter tend towards each other, and which they exert at all distances. It is by this attraction that the heavenly bodies are retained in their several places, by their action on each other, and it is also by this that a stone dropped from a height falls to the surface of the earth. It is one of the laws of nature, that every particle of matter gravitates towards every other particle. The planets and comets all gravitate towards A T W A T W C 77 JDICTION ARY OF MECHANICAL SCIENCE. the sun, and towards each other, as well as the sun towards them, and that in proportion to the quantity of matter in each. All terrestrial bodies tend towards the centre of the earth, consequently bodies fall every where perpendicular to its sur- face, and on opposite sides in opposite directions. As gravity acts upon all bodies in proportion to their quantities of matter, it is this attractive force that constitutes their weight. In all places equidistant from the centre of the globe, the force of gravity is equal. The force of gravity is greatest at the earth's surface, from whence it decreases both upwards and down- wards. Upwards the force decreases as the square of the distance from the centre increases; but below the surface of the earth the force of gravity decreases, so that at the distance of half a semidiameter from the centre, it is but half what it is at the surface; at one-third of the semidiameter, one-third; and so on for any other assumed distances. Gravity and weight are, in particular circumstances, synonymous terms. We say such a piece of lead weighs a pound, but if by any means it could be carried 4000 miles above the surface of the earth, it would only weigh four ounces; and provided it could be removed 8000 miles above the earth, which is three times the distance from the centre that the surface is, it would weigh only one-ninth of a pound. Again, since the force of gravity downwards decreases as the distance from the surface increases, 16 ounces would weigh, at one-half the distance from the centre to the surface, only eight ounces, and so on for one-third, &c. Hence, a piece of metal, &c. weighing on the surface of the earth one pound, will At the centre weigh . . . . . . . . . . . . . . • e o º ſº tº .0 t 1,000 miles from the centre. . . . . . . . . . . . # of a pound. 2,000 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . } 3,000 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . # 4,000 . . . . . . . . . . . . . tº e º s e e º 'º e º is a tº e < * * * ... 1 8,000. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . # 12,000 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ; ATTRIBUTES, in Theology, the several qualities or perfec- tions of the Divine nature: in Logic, the predicates of any sub- ject, or what may be affirmed or denied of any, thing: in fainting and Sculpture, symbols added to several figures, to intimate their particular office and character. Thus, the eagle is an attribute of Jupiter; the peacock, of Juno ; a club, of Her- cules; a trident, and chariot with sea-horses, of Neptune; of | Hope, an anchor; of Faith, a cross; &c. * ATWOOD'S MACHINE, (figure 119,) illustrates the doc- trines of accelerated motion, by subjecting to experimental examination the quantity of matter moved, the measure of the force which moves it, the space described from quiescence, the time of description, and the velocity acquired. The theory of this instrument depends upon principles usually exhibited in dynamics. - 1. Of the Mass moved.—In order to observe the effects of the moving force, which is the object of any experiment, the interference of all other forces should be prevented: the quantity of matter moved, therefore, considering it before any impelling force has been applied, should be without weight; for although it be impossible to abstract the natural gravity or weight from any substance whatever, yet the weight may be so counteracted as to be of no sensible effect in experiments. Thus, in the instrument constructed to illustrate this subject experimentally, AIB represent two equal weights affixed to the extremities of a very fine and flexible silk line: this line is stretched over a wheel or fixed pulley a b c d, moveable round an horizontal axis: the two weights, A B, being precisely equal and acting against each other, remain in equilibrio ; and when the least weight is superadded to either, (setting aside the effects of friction,) it will preponderate. When A B are set in motion by the action of any weight m, the sum A+B+m would con- stitute the whole mass moved, but for the inertia of the materials which must necessarily be used in the communica- tion of motion: these materials consist of, 1. The wheel a b c d, over which the line sustaining A and B passes. 2. The four friction wheels, on which the axle of the wheel a b c d rests: the use of these wheels is to prevent the loss of motion, which would be occasioned by the friction of the axle, if it revolved on an immoveable surface. 4. The line by which the bodies A ºi €5) P × t? & and B are connected, so as when set in motion to move with equal velocities. The weight cº and inertia of the line are QºSIC too small to have sensible Fic/119 all- effect on the experiments; */ \ 22- but the inertia of the other Cº. caº Hº materials just mentioned con- 2. H.F2 stitutes a considerable pro- portion of the mass moved, and must be taken into ac- count. Since, when A and B necessarily move with a ve- locity equal to that of the circumference of the wheel a b c d, to which the line is applied ; it follows, that if the whole mass of the wheels were accumulated in this cir- cumference, its inertia would be truly estimated by the Quantity of matter moved : but since the parts of the wheels move with different velocities, their effects in re- sisting the communication of motion to A and B by their inertia will be different; those parts which are furthest from the axis resisting more than those which revolve nearer, in a duplicate proportion of those distances. If the figures of the wheels were regular, from knowing their weights and figures, the distances of their centres of gyration from their axes of motion would become known, and conse- quently an equivalent weight, which being aceumulated uniformly in the circumfe- rence a b c d, would exert an º inertia equal to that of the wheels in their constructed form. But as the figures are Wholly irregular, recourse must be had to experiment, to assign that equivalent quantity of matter, which being accumulated uniformly in the circumference of the wheel a b c d, would resist the communication of motion to A in the same manner as the wheels. . In order to ascertain the inertia of the wheel a b c d with that of the friction-wheels, the weights AB being removed, the following experiment was made : Å weight of thirty grains was affixed to a silk line, (the weight of which was not so much as #th of a grain, and consequently too inconsiderable to have Sensible effect in the experiment;) this line being wound about the wheel a b c d, the weight 30 grains by descending from rest communicated motion to the wheel, and by many trials was observed to describe a space of about 38% inches in 3 seconds. Iº.ſ30 From these data the equivalent mass or inertia * “” of the wheels will be known from this rule: Let a weight, P., (fig. 120,) be applied to communicate motion to a system of bodies by means of a very slender and flexible line going round the wheel S L DIM, through the centre of which the axis passes, (G being the common centre of gravity, R R. the centre of gravity of the matter contained in this line, and O the centre of oscillation.) Let r! 'o this weight descend from rest through any con- in one second, the equivalent weight sought = I |M . venient space s inches, and let the observed time of its descent be t seconds; then if l be the space through which bodies descend freely by gravity w × S R × SO S D? sº-º-º: H – P. Here we have p = 30 grains, t = 8 seconds, X are put in motion, they must 78 A. T. W. A T W DIGTIONARY OF MECHANICAL scIENCE. P x, tºl 30 × 9 × 193 385 – 30 = 1323 grains, or 23 ounces. This is the inertia equiva- lent to that of the wheel a b c d, and the friction-wheels together; for the rule extends to the estimation of the inertia of the mass contained in all the wheels. The resistance to motion, there- fore, arising from the wheels’ inertia, will be the same as if they were absolutely removed, and a mass of 23 ounces were uniformly accumulated in the circumference of the wheel a b c d. This being premised, let the boxes A and B, fig. 119, be replaced, being suspended by the silk line over the wheel, or pulley a b cd, and balancing each other: suppose that any weight m be added to A, so that it shall descend, the exact quantity of matter moved, during the descent of the weight A, will be ascertained, for the whole mass will be A+ B + m +23 oz. In order to avoid troublesome computations in adjusting the quantities of matter moved and the moving forces, some deter- minate weight of convenient magnitude may be assumed as a standard, to which all the others are referred. This standard weight in the subsequent experiments is # of an ounce, and is represented by the letter m. The inertia of the wheels being therefore = 24 ounces, will be denoted by 11 m. A and B are two boxes, constructed so as to contain different quantities of matter, according, as the experiment may require them to be varied; the weight of each box, including the hook to which it is suspended, = 1% oz., or according to the preceding ºation, the weight of each box will be denoted by 6 m. ; these º - ºx. - contain Iº9.427. such weights as are represented . Aſ by fig, 122; each | of which weighs an ounce, so as to be equivalent to 4 m ; other - weights of 3 oz. = 2 m, 3 = m, and aliquot parts of m, such as 3, 4 m, may be also included in the boxes, according to the conditions of the different experiments hereafter described. If 43 oz. or 19n, be included in either box, this, with the weight of the box itself, will be 25 m; so that when the weights A and B, each being 25 m, are balanced in the manner above represented, their whole mass will be 50 m, which being added to the inertia of the wheels 11 m, the sum will be 61 m. More- over, three-circular weights, such as that which is represented at fig. 122, are constructed; each of which = 4 oz. or m : if one of these be added to A and one to B, the whole mass will now become 63 m, perfectly in equilibrio, and moveable by the least weight added to either, (setting aside the effects of friction,) in the same manner precisely as if the same weight or, force were applied to communicate motion to the mass 63 m, existing in free space and without gravity. 2. The moving Force. Since the natural weight or gravity of any given substance is constant, and the exact quantity of it easily estimated, it will be convenient here to apply a weight to the mass A as a moving force : thus, when the system con- sists of a mass = 63 m, according to the preceding description, the whole being perfectly balanced, let a weight 3 oz. or m, such as is represented in fig. 123, be applied on the mass A ; this will communicate motion to the whole system: by adding a quantity of matter m to the former mass 63 m, the whole quantity of matter moved will now become 64m; and the mov- ing force being = m, this will give the force which accelerates %, the descent of A = GTi, or * part of the accelerating force by which the bodies descend freely towards the earth's surface. By the preceding construction, the moving force may be altered without altering the mass moved; for, suppose the three weights m, two of which are placed on A, and one on B, to be removed, then will A balance B. If the weights 3 m be all placed on A, the moving force will now become 3 m, and the – P= 1-193inches, s- 38.5inches; and Fy:422 mass moved 64 m as before, and the force which accelerates | 3 - the descent of A = #= # parts of the force by which | gravity accelerates bodies in their free descent to the surface. Suppose it were required to make the moving force 2 m, the mass moved continuing the same. In order to effect this, let the three weights, each of which = m, be removed; A and B will balance each other; and the whole mass will be 61 m : let 3 m fig. 123, be added to A, and 3 m to B, the equilibrium will still be preserved, and the mass moved will be 62 m; now let 2 m be added to A, the moving force will be 2 m, and the mass moved 64 m as before; wherefore the force of accelera- tion = }; part of the acceleration of gravity. These alterations in the moving force may be made with great ease and conve- nience in the more obvious and elementary experiments, there being no necessity for altering the contents of the boxes. A and B; but the proportion and absolute quantities of the moving force and mass moved may be of any assigned magnitude, according to the conditions of the proposition to be illustrated. 3. Of the Space described.—The body A, fig. 119, descends in a vertical line; and a scale about 64 inches in length graduated into inches and tenths of an inch is adjusted vertically, and so placed that the descending weight A may fall in the middle of a square stage, fixed to receive it at the end of the descent: the beginning of the descent is estimated from o on the scale, when the bottom of the box A is, on a level with o. The descent of A is terminated when the bottom of the box strikes the stage, which may be fixed at different distances from the point of so that by altering the position of the stage, the space described from quiescence may be of any given magnitude less than 64 inches. - - - 4. The Time of motion, is observed by the beats of a pendulum, which vibrates seconds; and the experiments, intended to illustrate the elementary propositions, may be easily so con- structed, that the time of motion shall be a whole number of seconds : the estimation of the time, therefore, admits of con- | siderable exactness, provided the observer takes care to let the bottom of the box A begin its descent precisely at any beat of the pendulum; then the coincidence of the stroke of the box against the stage, and the beat of the pendulum at the end of the time, of motion, will shew how nearly the experiment and the theory agree together. There might be various mechanical devices thought of for letting the weight A begin its descent at the instant of a beat of the pendulum W: let the bottom of the box A, when at o on the scale, rest on a flat rod, held in the hand horizontally, its extremity being coincident with o ; by attending to the beats of the pendulum, and with a little practice, the rod which supports the box. A may be removed at the moment the pendulum beats, so that the descent of A shall commence at the same instant. 5. Of the Velocity acquired.—It remains only to describe in what manner the velocity acquired by the descending weight A, at any given point of the space through which it has descended, is made evident to the senses. The velocity of A's descent being continually accelerated, will be the same in no two points of the space described. This is occasioned by the constant action of the moving force; and since the velocity of A at any instant is measured by the space which would be described by it, moving uniformly for a given time with the velocity it had acquired at that instant, this measure cannot be experimentally obtained, except by removing the force by which the descending body’s acceleration was caused. In order to shew in what manner this is aſſected practically, let us again suppose the boxes A and B = 25 m each, so as together to be = 50 m ; now let m, fig. 121, be added to A, and an equal weight m to B, these bodies will balance each other, and the whole mass will be 63 m. If a weight m be added to A, motion will be communicated, the moving force being m, and the mass moved 64m. In estimating the moving force, the circular weight = m was made use of as a moving force: but for the present purpose of shewing the velocity acquired, it will be convenient to use a flat rod, the weight of which is also = m. Let the bottom of the box A be placed on a level with o on the scale, the whole. mass being as deseribed above = 63 m, perfectly balanced in equilibrio. Now let the rod, the weight of which Em, be placed on the upper surface of A; this body will descend along the scale precisely in the same manner as when the moving force was applied in the form of a circular weight. Suppose the mass A, (fig. 124.) to have deseeaded by A T W A U R '79 DICTIONARY OF MECHANICAL SCIENCE. eonstant acceleration of force of m, for any given time, or through a given space: let a circular frame be so affixed to the scale, contiguous to which the weight descends, that A may pass centrally through it, and that this circular frame may intercept the rod; m, by which the body A has been accelerated from quiescence. After the moving force m has been inter- cepted at the end of the given space or time, there will be no force. operating on any part of the system, which can acce- lerate or retard its motion: this being the case, the weight A, the instant after m has been removed, must proceed uniformly with the velocity which it had acquired that instant: in the subsequent part of its descent, the velocity being uniform, will be measured by the space described in any convenient number of seconds. the impact of bodies elastic and non-elastic ; the quantity of resistance opposed by fluids, as well as for various other pur- poses. The properties of retarded motion are a part of the present subject, and may be necessary to shew in what manner the motion of bodies resisted by constant forces are reduced to experiment by means of the instrument above described, with as great ease and precision as the properties of bodies uniformly accelerated. . A single instance will be sufficient: . Thus, suppose the mass contained in the weights A and B, fig. 121, and the wheels to be 61m, when perfectly in eqnilibrio ; let a circular weight m be applied to B, , and let two long weights or rods, each E m, be applied to A, then will A descend by the action of the moving force m, the mass moved being 64 m : suppose that when it has described any given space by . constant acce- leration, the two rods m are intercepted by the circular frameabovede- scribed, while A, is descend- ing through it, the velocity ac- ; t]uired by that. descent is known; & when the two rods are intercept- ed, the weight will begin to move on with the velocity ac- quired, being now retarded. by the constant force my and since the mass moved 1s 62 m, it follows that the force of retardation will be 3, part of that force whereby gravity retards bodies thrown perpendicularly up- wards. The weight A will therefore proceed along the graduated scale in its descent with an uniformly retarded motion, and the space described, times of motion, and velocities destroyed by the resisting force, will be subject to the same measures as in the examples of accelerated motion above described. In the fore- going deseriptions, two suppositions have been assumed, neither of which is mathematically true: but it may be easily shewn that they are so in a physical sense; the errors occa- sioned by them in practice being insensible. * Among other uses of the instrument, is the experimental estimation of the velocities communicated by 1. The force which communicates'motion to the system has been assumed constant; which will be true only on a supposi- tion that the line, at the extremities of which the weights A and B, fig. 119, are affixed, is without weight. In order to make it evident that the line's weight and inertia are of no sensible effect, let a case be referred to, wherein the body A descends through 48 inches from rest by the action of the moving force m, when the mass moved is 64m ; the time wherein Å describes 48 inches is increased by the effects of the line's weight by no more than Tººth parts of a second; the time of descent being 3-9896 seconds, when the string's weight is not considered, and the time when the string's weight is taken into account E4'0208 seconds; the difference between which is wholly insensible by observation. 2. The bodies have also been supposed to move in vacuo, whereas the air's resistance will have some effect in retarding their motion: but as the greatest velocity communicated in these experiments cannot much exceed that of about 26 inches in a second, (suppose the limit 26°2845,) and the cylindrical boxes being about 13 inches in diameter, the air’s resistance can never increase the time of descent in so great proportion as that of 240 : 241; its effects therefore will be insensible in experiment. The effects of friction are almost wholly removed by the friction-wheels; for when the surfaces are well polished and free from dust, &c. if the weights A and B be balanced in perfect equilibrio, and the whole mass consists of 63 m, accord- | ing to the example already described, a weight of 13 grain, or at most 2 grains, being added either to A or B, will communi- cate motion to the whole ; which shews that the effects of fric- tion will not be so great as a weight of 1% or 2 grains. In some cases, however, especially in experiments relating to retarded motion, the effects of friction become sensible; but may be very readily and exactly' removed by adding a small weight of 1'5 or 2 grains to the descending body, taking care that the weight added is such as is in the least degree smaller than that which is just sufficient to set the whole in motion, when A and B are equal, and balance each other before the moving force is applied.—The foregoing article is taken nearly verba- tim from Dr. Gregory's Mechanics; and the instrument may be purchased for £28, at Harris’s, 50, High Holborn. AUGUST, the eighth month of the year, when we have in Season—of Meat: beef, mutton, veal, lamb, buck, venison, &c. Poultry: pullets, fowls, chickens, green geese, turkey poults, ducklings, leverets, rabbits, pigeons, pheasants, wild ducks, wheatears, plovers. Fish : cod, haddock, flounders, plaice, skate, thornback, mullets, mackarel, herrings, pike, carp, eels, lobsters, crawfish, prawns, oysters. Vegetables: carrots, tur- nips, potatoes, radishes, onions, garlic, shalots, scorzonera, Salsifie, peas, beans, kidney beans, mushrooms, artichokes, cabbages, cauliflowers, sprouts, beets, celery, endive, pinocha, parsley, lettuce, salads, thyme, marjoram, sweet herbs, savoy. Fruit: peaches, nectarines, plums, cherries, apples, pears, grapes, figs, filberts, mulberries, strawberries, gooseberries, currants. melons, pineapples. The Botanical Kalendar for August.—Many seeds and herba- ceous vegetables ripen in this month, and most of the culinary crops raised in the open garden, are now in perfection. Insects, especially the winged tribes of butterflies, abound, and the gardener should destroy them, or collect them for specimens. Numbers of beautiful insects may thus be gathered, even while at work. The young martins begin to congregate ; bees kill their drones; numerous birds resume their spring notes; the goatsuck- ers and young owls hoop and make a noise in the evenings. Melilot, yellow succory, burdock, tobacco, wild clary, meadow rice, plowman's spikenard, mallows, hollyhocks, lobelias, cro- cuses, &c. are in flower. Bread corns ripen, and the earlier varie- ties of all the kernel fruits ripen. Sow turnips for a main crop early in this month, salads, radishes, parsley, spinage, carrots, endive, chervil, for winter and spring crops; cauliflowers to stand over winter, in sheltered borders and under frames. Propagate by slips and cuttings; transplant leeks and peren- nials; hoe, thin, weed, and stir winter crops; clear off all crops the moment they are done with ; gather pickling cucumbers and ripe seeds. Plant strawberries; prune, regulate, and train summer shoots of wall trees and espaliers. Mat up all fruits on north walls, intended to be preserved till late in 80 A U R A U. R. DICTIONARY OF MECHANICAL SCIENCE. autumn. Gather gooseberries, currants, and all ripe fruit. Plant evergreens, repair lawns, destroy ferns, nettles, and weeds about park scenery and fences. Take up bulbs, trans- plant biennials, &c. AULA Regis, a court established by William the Conqueror, in his own hall, and composed of the great officers of state. The 11th article of Magna Charta regulates this court, which is now established in Westminster Hall. See KING’s BENCH. AULIC Council, composed of the great officers of the Ger- man empire, always follows the emperor's court, but ceases on his death; whereas the imperial chamber of assize is perpetual, and represents not only the deceased emperor, but the whole Germanic body. AULic, in the Sorbonne, &c. is an act which a young divine maintains, upon being admitted a doctor of divinity. It commences by an harangue of the chancellor, addressed to the young doctor, after which he receives the cap, and presides at the aulic or disputation. AURIGA, in Astronomy, the Waggoner or Charioteer, a mere type or scientific symbol of that beautiful fable which is given us of Phaeton; or, more properly, he may be the attendant of Phoebus at that remote period when Taurus opened the 'year. The boundaries and contents of this constellation are these :-North by Camelopardalis, east by Lynx, Herschel's Telescope, and Gemini; south by Taurus, and west by Per- seus. Auriga contains 66 stars, one of the 1st magnitude, two of the 2d magnitude, nine of the fourth, &c. The declimation generally is 45° north, and its right ascension 75°. A large portion of this constellation is always above the horizon to the British isles, and consequently to all places in corresponding latitudes. The Charioteer's head passes vertically over England and Ireland. The most remarkable star in this constellation, and indéed in this quarter of the firmament, is Capella, of the 1st magnitude, situated on Auriga's left, or western shoulder; its north declination is 45° 47' 18", and its right ascension 75° 51' 3", or 5 hours 3 minutes in time. Capella culminates for the first day of each month in the year, as follows; and by adding 12 hours to the culminating of this or any other star, we determine the time it is on the meridian under the pole. Meridian altitude, 84° 16' 18" north. MonTH, CULM. MONTH, I CULM. MonTH. " CULM. ho. mi. ho. mi. ho. mi. Jan. 10 15 A. May 2 45 A. Sept. 6 || 5 M. Feb. 8 S A. June 12 55 A. Oct. 4 22 M. March 6 20 A. July 10 20 M. Nov. 2 30 M. April 4 30 A. Aug. 8 15 M. Dec. 12 30 M. AURORA BOREALIS, or Northern Twilights, or streamers, may be defined an electrical phenomena, or aerial electricity, which is seen generally in the winter time, and in frosty wea. ther and clear evenings, in the Hyperborean regions of the skies. This meteor assumes every variety of tint that embellishes the iris or rainbow, but wears generally a fiery and purple hue. Its appearance is indeed now so generally known, even in this country, that a more particular description is not requisite: but it may be just observed, that as we only see the extremities of this brilliant phenomenon, we can have but a faint idea of its real splendour in the arctic regions, where it appears in perfection, and proves a great solace to the inhabitants amidst the gloom of the long winter nights. In some parts of Siberia, particularly, this beautiful meteor is constantly exhibited from October to Christmas, and its radiating beams in those parts are remarkably bright. Captain Ellis, who wintered on the western coast of Hud- son's Bay in North America, observes, that no sooner does the Sun disappear in those regions, than the aurora borealis diffuses- a thousand different lights and colours over the whole con- cavity of heaven, with such resplendent beauty, that even the full moon cannot eclipse their lustre. It was for a long time a matter of doubt whether this meteor made its appearance in the southern hemisphere; but Mr. Foster, who went round the world with Captain Cook, ascertained the fact, Feb. 17, 1773, in lat. 58° south, though it appeared with phenomena some. what different from ours. Concerning the cause of the aurora borealis, many conjectures have been formed; but that which seems to be supported by the most specious reasoning ascribes its origin to electricity. It is supposed, that most of the extraordinary meteors and appearances in the skies, related as prodigies by historians, e. g. battles, and the like, may be pro- bably enough reduced to the class of aurora, boreales. In certain states of the atmosphere these phenomena have some- times assumed the colour of blood, and made a dreadful appearance. At these times the rustic sages became pro- phetic, and terrified the gazing spectators with the dread of wars, pestilence, and famine : even persons more enlightened Supposed them to be portentous of great events, and timid imaginations shaped them into aerial conflicts. Captain Franklin enumerates auroa Borealis, at one time, in form of a bright arch, extending across the zenith, in a north-west and south-east direction,--at another, it was extremely brilliant, its coruscations darting at times over the whole sky, and assuming various prismatic colours, of which violet and yellow were predominant, again, its appearances were greatly diversified, and its motion extremely rapid, its coruscations occasionally concealed stars of the first magni- tude in passing over them; once a stream of light illumined the under surface of some clouds as it passed along :—these appearances were visible in the winter. In the spring the aurora was very brilliant and variable; at one time exhibiting illu- mined beams issuing from the horizon in the north, east, and west points, and directed towards the zenith; in a few scoonds these disappeared, and a complete circle was displayed, bounding the horizon at an elevation of 15°. There was a quick lateral motion, in the attenuated beams of which this Zone was composed. Its colour was pale yellow, with an occa- Sional tinge of red. On another occasion, the aurora borealis appeared from north-west to south-east, in an arch across the Zenith, which afterwards gave place to a beautiful corona borealis. - - In the month of Jan. 1821, the aurora appeared with more or less brilliancy on 28 nights, and for many days together the resplendent moon whirled in circles round the heavens, Shining with undiminished lustre, and scarcely disappearing below the horizon during the twenty-four hours. But Captains Franklin and Parry, and Dr. Richardson, who have added to our already accumulated facts relative to this curious phenomenon, have thrown no light on its theory. Now it is known that the luminous beams of this meteor are all cylindrical, and, over a certain extent of country, parallel to one another. And if these cylindrical beams are magnetic, and parallel to the dipping needle at the places over which they appear, then is the aurora borealis a purely magnetic phenomenon, whose beams are governed by the earth’s mag- netism. And this is the more probable, as the distance of these beams from the earth is nearly equal to their length; the rainbow-like arches being about 150 miles above the earth's Surface. - Lieutenant Back, the brave companion of Captain Franklin, relates that, in the same journey to the Polar sea, he imagined more than once, whilst listening attentively in the silence of midnight on the wilds of the American lakes, and gazing on the fantastic beauties of the aurora borealis, he heard a rustling noise, like that of autumnal leaves stirred by the wind. This, however, he thinks was but illusion. The aurora was very sluggish and dim, otherwise he has little doubt he should have ascertained this yet undecided fact. One of the partners of the North West company affirmed, however, that on one occa- sion amidst these solitudes, he saw the coruscations of the aurora so vivid and low, that the Canadians fell on their faces, fearing they should be killed: he himself threw away his gun and his knife, that he might not attract the flashes, which were within two feet of the earth, flitting along with incredible swift- ness, and moving parallel to its surface, making a loud rustling noise like the waving of a flag in a strong breeze. On another occasion these lights rose about north-west, divided into three bars, diverging at equal distances, as far as the zenith, and then converging till they met in the opposite horizon; there were some flashes emitted at right angles to the bars. At another time the coruscations were so bright as tº discover eight wolves prowling about the voyagers. Heavy storms Were at some places generally anticipated by the activity of the aurora borealis; though not invariably so in other parts of the Country. - - A U. R. A U T DICTIONARY OF MECHANICAL SCIENCE. 81 f fully described by Thomson as — Silent from the north - A blaze of meteors shoots; ensweeping first The lower skies, they all at once converge High to the crown of heaven, and all at once Relapsing quick, as quickly reascend, - And mix, and thwart, extinguish and renew, All ether coursing in a maze of light. And analogous to this are those luminous arches so beauti- In March, 1774, a very beautiful luminous arch was seen at Buxton. It was white, inclining to yellow ; and its breadth in the crown apparently equal to that of the rainbow. As it approached the horizon, each leg became gradually broader. It was station- ary, and free from any sensible coruscations. Its direction was from north-east to south-west; and its crown or most elevated part not far from the zenith. This phenomenon lasted about half an hour. The grandest spectacle of this kind, seen in Great Britain, was observed at Leeds, on the 12th of April, 1783, between nine and ten at night. A broad arch of a bright pale yellow, with an apparent breadth of about 15°, arose in the heavens, and passed considerably south of the zenith; by its varied density, it appeared to consist of small columns of light, with a sensible motion. After about ten minutes, innumerable bright coruscations shot out at right angles from its northern edge, elongating themselves till they had nearly reached the northern horizon. As they descended, their extremities were tipped with an elegant crimson, like that pro- duced by the electric spark in an exhausted tube. After some time this beautiful northern light ceased to shoot, and, forming a range of bright yellow clouds, extended horizontally about the fourth of a circle; its greatest portion, which darted from this arch northwards, as well as the cloud-like and more stationary aurora, became so dense as to hide the stars from view. The moon was eleven days old, and shone brightly during this scene, but did not eclipse the splendour of these coruscations. The wind was in the north, a little to the east. A similar phenomenon was observed at Leeds on the 26th of the same month, the west, issued three luminous arches, each of which made a different angle with the horizon. They had not been viewed many minutes when they were rendered invisible by a general blaze of aurorae boreales, which possessed the space just before occupied by these arches. AURUM, Gold. This most precious of all the metals is usually found in a perfectly pure state, possessing a fine rich yellow colour, and a degree of ductility altogether incredible. By far the most copious supplies occur in alluvial soils, situated along the foot of large ranges of mountains, from which it is apparently washed down by the rivers. It occurs likewise, though in smaller quantities, in veins and beds diffused through granite, gneiss, and other primitive rocks; also in porphyry and sand-stone ; and it is generally accompanied with quartz. and iron pyrites. Alluvial gold is found in the district of Leadhills in Scotland ; and it is reported that, in the time of queen Elizabeth, the metal was there collected to the amount of £100,000. It appears also in Glen Turret, in Perthshire, some parts of Cornwall, and in Ireland, near Arklow, in the county of Wicklow. In all those places, however, it presents itself rather as an object of curiosity than of any real value. The same may be said of the veins which occur in primitive rocks in Salzburg, the Tyrol, Transylvania, and at Edelfors, in Sweden, as well as of the golden sands poured down by the Danube, Rhine, Tagus, and other European rivers. Africa is much more prolific of this valued metal. All the streams which flow from the great mountain-ranges in the centre of that eon- tinent appear to impregnate their sands with gold. It is found most copiously in Bambouk, Manding, Wangara, and the countries behind the Gold coast. A large quantity is also collected in the mountains behind Mosambique. The islands of Sumatra, Borneo, and Celebes, in the East Indies, contain large storºs of alluvial gold, the working of which has been so much improved by the industry of the Chinese, as to render those regions nearly independent of supply from the west. Nothing on the globe, however, can equal the abundance in which the gold occurs throughout the vast regions of South. which would otherwise pass round them. From a mass or broad column of light in America. The Mexican gold is chiefly alluvial, but partly found in primitive mountains, and mixed with silver, in the mines of that metal. The situation of the Peruvian gold is nearly similar, but the mines do not pay the expense of work- ing, and the chief riches here, as elsewhere, is obtained by washing. The ample supply of gold which is drawn from Brazil is entirely alluvial, deposited along the foot of that great range of mountains which forms the western frontier of that set- tlement. Humboldt calculates the entire annual produce of the Spanish colonies at 25,000lbs. troy, and that of the Portu- guese at somewhat above 20,000. Gold occurs in three other forms, called by Werner brass yellow, grayish yellow, and electrum, or argentiferous native gold. These occur in different parts of Europe, but in such small quantity as not to deserve much consideration here. The ductility and malleability of gold is so great, that its limits are unknown. The weight of a single grain of fine gold leaf will cover 57 square inches. Calculating the specific gravity of the metal with this admeasurement, we find, that 282,000 of these leaves put together would only be an inch thick. It is nevertheless evident that gold is capable of much greater extension, as the gold-beaters are obliged to alloy the gold with copper, to make it hard enough to pass over the irregularities in the skins, It is likewise proved by the silver-gilt wire used for lace-making, which is drawn . from an ingot of silver previously gilded. Calculating the length and circumference of the wire thus drawn, it is found that the weight of a grain of gold thus employed, has spread itself over a surface of twelve times greater extent than is done by the gold-beaters in making it into leaves; therefore it follows, if the gold could be made into leaves as thin as thé covering upon the silver wire, that it would take 3,384,000 leaves to make an inch in thickness. - • AURUM-MUsivum, used by the japanners, and for varnished works, as snuff-boxes, coaches, &c. has all the beautiful appear- ance of gold in powder. Amalgamate twelve parts of the purest tin with three parts of mercury; the amalgam is then triturated in a stone mortar with seven parts of flowers of sulphur and three parts of sal ammoniac. The mixture is next put into a matrass, and the whole exposed to a gentle sand-heat, until no more white fumes arise. ... When, upon this, the heat is some- what raised, cinnabar sublimes, together with some oxygenated muriate of tin: while at the same time, the remaining tin and sulphur unite, forming the aurum musivum, exhibiting a golden yellow and flaky and scaly matter, of a metallic lustre. The main point in this process is the proper regulation of the fire.: when too strong, the operation does not succeed; and instead of aurum musivum, the common sulphuret of tin is obtained. AUSTRAL, the same as southern ; thus we say, Australis Corona, Australis Piscis, for Southern Crown, and Southern Fish. See CoRo NA and Piscis. - AUTOMATON, a seemingly self-moving machine ; or one * so constructed, by means of weights, levers, pulleys, springs, &c. as to move for a considerable time, as if it were endued with animal life. And according to this description, clocks, watches, and all machines of that kind, are automata. It is said that Archytas of Tarentum, four hundred years before Christ, made a wooden pigeon that could fly; that Archimedes also made similar automata; that Regionontanus made a wooden eagle that flew forth from the city, met the emperor, saluted him, and returned; also that he made an iron fly, whic flew out of his hand at a feast, and returned again after flying about the room; that Dr. Hooke made the model of a flying cha- riot, capable of supporting itself in the air. Many curious and surprising automata have been witnessed in the present age : thus, we have seen figures that could write, and perform many other actions in imitation of animals : M. Vaucanson made a figure that played on the flute; the same gentleman also made a duck, which was capable of eating, drinking, and imitatittg exactly the voice of a natural one ; and, what is still Rogré sºlº- prising, the food it swallowed was evacuated in a digested state, or considerably altered on the principles of solution; also the wings, viscera, and bones, were formed so as strongly to resemble those of a living duck; and the actions of eating and drinking shewed the strongest resemblance, even to the muddling the water with its bill. M., lc Droz, of Neufchâtel, has Y $3 A tř ºf ălă8 8x86tted $6the very bufiods piédés 6f mechanism i öhe was a clbek, présefited to the king, of Spain, which had; ambHg othèf curiosities, a sheep that imitated the bleating of aftātāraīohé, and a dog watching a basket of fruit, that barked ańd Sharled when any one offered to také if away; besides a Variety of human figures, exhibiting motions truly º Thé àtitórhátéfi chess-player is yet more surprising. This Wonderful piece of méchanism, the invention of M. de Kémplin, ah Hungafian géntleman, has for may years lain dormant. It was brölight to England in the year i817, and exhibited in the #éat fööm, Spring Gardens, Londoñ, and in other places, to hé admiration arid satisfaction of thousands. whéré it is exhibited, has an inner apartment, within which #. the figure of a man, as large as life, dressed after the Turkish fashion, sitting behind a chest three and a half feet iñ º, two feet in breadth, and two feet and a half in height; to which it is attached by a wooden seat. The chest, is plačéd upon four castors; and, together with the figure, may bé fùùved to any part of the room. On the plain surface, formed by the top of the chest, in the centré, is a raised immoveable chèss-board, upon which the figuré has its eyes fixed; its right arm and hand being extended on the chest, and its left arm holding a Turkish tobacé0-pipe. . The exhibitor begins by wheeling the chest to the entrance of the apartment within which it stands, and in face of the spectators. . He then opens certain döors in the chest, two in front, and two at thë back, at the same time ptilling out a long shallow ğrawéi ſãt the bottom, which contains the chess-men, a cushion For the #iºn of the figure to rest àpoh, and some counters. Twó Hesser doors, and a green cloth screen, contrived in the bööyüf the figure, and its lower parts, are likewise opened, and the Turkish robe which covers them is raised; so that the ºëhstrüctiên both of the figure and chest internally is displayed. :Eh this state the automaton is moved round for the examina- fion of the spectators; and to banish all suspicion that any hiving thing is concealed within any part of it, the exhibitor iñtródùces a lighted candle into the body of the chest and figure, by which the interior of each is, in a great measure, Yêndèred transparent, and the most secret corner is shewn. Here it may be observed, that the same precaution to remove suspición is used, if requested, at the close as at the com- ifiemièément of a game of chess with the automaton. The chest is divided, by a partition, into two unequal chambers. That to the right of the figure is the narrowest, and occupies scarcely one-third of the body of the chest. It is filled with little wheels, levers, cylinders, and other machinery used in clock-work. That to the left contains a few wheels, some 'small barrels with springs, and two quarters of a circle placed horizontally. The body and lower parts of the figure contain tubes, which seem to be conductors to the machinery. After a sufficient time, during which each spectator may satisfy his scruples and his curiosity, the exhibitor re-closes the doors of of the chest and figure, and the drawer at bottom; makes Söme arrangements in the body of the figure; winds up the works with a key inserted into a small opening on the side of . the chest; places a cushion under the left arm of the figure, which fibw rests upon it; and invites any individual present to play a game of chess. In playing a game, 'the automaton makes choice of the white pieces, and always has the first move. These are small advantages towards winning the game, which are cheerfully conceded. It plays with the left hand, the right arm and hand being constantly extended on the chest, behind which it is seated. This slight incongruity proceeded 'from absence of mind in the inventor, who did not perceive his mistake till the machinery of the automaton was too far ‘completed to admit of the mistake being rectified. At the commencement of a game, the automaton moves its head, as if taking a view of the board; the same motion occurs at the close of a game. In making a move, it slowly raises its left 'arm from the cushion placed under it, and directs it towards. the square of the piece to be moved. Its hand and fingers. ‘open on touching the piece, which it takes up, and conveys to any proposed square. The arm then returns with a natural ‘motion to the cushion, upon which it usually rests. In taking, "a pièce, the automatón makes the same Hiótions of the arm fjíčfiðNARY &f M #0 iſ ANickf, Sć ºn Cº., ands... We shall here give à description of its mechanism and operations. The room, A W 0. and hand to lay hôld of the piece, which it conveys from the board; and then, returning to its own piece, it takes it up, and places it on the vacant square. These motions are per- formed with perfect correctness; and the dexterity with which the arm acts, especially in the delicate operation of castling, seems to be the result of spontaneous feeling, bending at the shoulder, elbow, and knuckles, and º avoiding to touch any other piece than that which is to be moved, nor ever making a false move. After a move made by its anta- gonist, the automaton remains for a few moments inactive, as if meditating its next move ; upon which the motions of the left arm and hand follow. On giving check to the king, it moves its head as a signal. hen a false move is made by its antagonist, which frequently occurs through curiosity to observe in what manner the automaton will act, (as, for instance, if a knight be made to move like a *; the automaton taps impatiently on the chest with its righ hand, replaces the knight on its former square, and, not per- mitting its antagonist to recover his move, proceeds immedi- ately to move one of its own pieces, thus appearing to punish him for his inattention. The fittie advantage in play which is hereby gained, makes the automaton more a match for its antagonist; and seems to have been contemplated by the inventor as an additional resource towards winning the game. —It is of importance that the person matched against the auto- maton should be attentive, in moving a piece, to place it pre- cisely in the centre of its square; otherwise, the figure, in attempting to lay hold of the piece, may miss its hold, or even sustain some injury in the delicate mechanism of the fingers. When the person has made a move, no altera- tion in it can take place; and if a piece be touched, it must be played somewhere. This rule is strictly observed by the automaton. If its antagonist hesitate to move for a consider- able time, it taps smartly on the top of the chest with the right hand, which is constantly extended upon it, as if testifying impatience at his delay. During the time that the automaton is in motion, a low sound of 'clock-work is heard, which ceases soon after its arm returns to the cushion, and then its antago- mist may make his move. The works are wound up at inter- vals, after ten or twelve moves, by the exhibitor, who is usually employed in walking up and down the apartment in which the :automaton is shewn; approaching the chest however, from time to time, especially on its right side. - AUTUMN, the third season of the year: this begins at the descending equinox, which, in the northern hemisphere, is when the sun enters the sign Libra, about the twenty-second of August, and ends about the same day in December. AUTUMNAL Equinox, the time when the sun enters the tte- scending point of the ecliptic, where it crosses the equinoctial. AUTUMNAL Point, the point of the ecliptic answering to the autumnal equinox. - AUTUMNAL Signs, are the signs Libra, Scorpio, Sagittarius, through which the sun passes during autumn. AVIARY, a place set apart for rearing and feeting birtis, which should be so large as to afford the birds some scope to fly about, and if turfed, there will be no appearance of dirt. Good stout small net, doubled, makes a goob fence for an aviary; but wire is much better. . - *: AVOIDANCE, in the Canon Law, is when a benefice becomes void of an incumbent, which happens eitherinfact, as by the death of the person; or in law, as by cession, depriva- tion, resignation, &c. In the first of these cases the patron must take notice of the avoidance at his peril; but in avoid- ance by law, the ordinary is obliged to give notice to the patron in order to prevent what is termed an’élapse. AVOIRDUPOIS, the weight for the larger and coarser ‘commodities; such as groceries, lead, &cº. Apothecaries buy by avoirdupois, but sell by troy weight. The proportion of a pound avoirdupoisºto a pound troy is as 17 to 14. AWOWEE, one who has a right to present to a benéfice. He is so called in contradistinction to those who only have the lands to which the advowson belongs, for a term of years, or by virtue of intrusion or disseisin. AVOWRY, in Law, is when a person distrained 'sues out 'a replevin; for then the distrainer must avow and justify his plea, for distraining whiêh is called his avowry. - A X I A Z i §§ DIGITIONARY OF MECHANICAL $0.15 NCE. AXIOM, a self-evident truth, or a proposition, the truth of which is perceived at first sight. Thus, that a whole is greater than a part; that a thing cannot be, and not be, at the same time; and that from nothing, nothing can arise; are self-evi- dent truths, or axioms. Axiom is also an established principle in some art or science. Thus, it is an axiom in geometry, that things which are equal to the same thing, are equal to each other; that if to equal things, equal things be added, the wholes will be equal, &c. - . . . AXIS, in Astronomy, an imaginary right line, supposed to pass through the earth, sun, planets, satellites, &c. and about which they perform their respective diurnal rotations. The earth and planets, in their progress through the annual orbit, move in such a manner that the axis of each always keeps parallel to itself, or points to the same parts of the heavens. The axis of the earth is inclined to the ecliptic in an angle of nearly 664°, a position which is well adapted for promoting the fertility of the earth, and rendering it habitable. Dr. Keill has pointed out many advantages which result from this inclination of the axis, particularly in ripening the fruits of the earth; and he has proved the truth of much that was advanced by Kepler to the same effect. Among other curious particulars, Keill has shewn, that all who live beyond 45° of latitude, and have greatest need of the sun's heat, have more of it during the whole year than if the equator and ecliptic coincided ; whereas they who live between the equator and 45° of latitude, and are rather too much exposed to the sun than too little, have, on account of the present inclination, less of the sun's heat than if the earth were in the position of a right sphere. Axis of the Horizon, Equator, &c. is a right line drawn through the centre of the respective circle, perpendicular to its plane. Axis, in Geometry, the straight line in a plane figure, Åbout which it revolves, to produce or generate a solid. Thus, if a semicircle be moved round its diameter at rest, it will generate a sphere, whose axis is that diameter. And if a right-angled triangle be turned about its perpendicular at rest, it will describe a cone, whose axis is that per- pendicular. b. Axis is yet more generally used for a rightline conceived to ºbe drawn from the vertex of a figure to the middle of the base. So the - Axis of a Circle or Sphere, is any line drawn through the centre, and terminated at the circumference, on both sides. Axis of a Cone, is the line from the vertex to the centre of the base. Axis of a Cylinder, is the line from the eentre-of the one end to that of the other. Transverse Axis, in the ellipse and hyperbola, is the diameter passing through the two foci, and the two principal vertices of the figure. In the hyperbola it is the shortest diameter, but ‘in the ellipse it is the longest. Conjugate Axis, or Second Axis, in the ellipse and hyperbola, is the diameter passing through the centre, and perpendicular to the transverse axis. It is the shortest of all the conjugate diameters. Axis of a Curve Line, is still more generally used for that diameter which has its ordinates at right angles to it, when %hat position is possible. ‘Azis, in Mechanics, a certain line about which a body, may turn. Axes are of various kinds; as, Axis of a Balance, the line upon which it moves or turns. Axis of Rotation, the line about which a body really revolves, when it is put in motion. The impulse given to a homoge- “neous sphere, in a direction which does not pass through its centre, will cause it to revolve constantly round the diameter, which is perpendicular to a plane passing through its centre, and the line of direction of the impressed force. New forces acting on all its parts, and of which the result passes through ‘its centre, will not change the parallelism of its axis of rota- 'tion. Thus it is, that the axis of the earth remains always nearly parallel to itselfin its revolution round the sun, without its being necessary to suppose, with Copernicus, an annual motion of the poles of the earth round those of the ecliptic. *If the body possess a certain figure, its axis of rotation may “bhange-every instant. The determination of these changes, whatever may be the forces acting on the badies, is one of the most interesting problems of mechanies respecting hard bodies, on account of its connexion with the precession of the equir noxes, and the libration of the moon. The solution of this problem has led to a curious and very useful result; namely, that in all bodies there exist three axes perpendicular to each other, round” which the body may turn uniformly when not Solicited by external forces. On this account, these axes are properly called principal axes of rotation. AXIS of Oscillation, is a line parallel to the horizon, passing through the centre, about which a pendulum yibrates, and perpendicular to the plane in which it oscillates. Axis in Peritrochio, one of the five mechanical powers, con- sisting of a peritrochium or wheel, and moveable together with it about its axis. The power is applied at the circumference of the wheel, and the weight is raised by a rope that is gathered up on the axis while the machine turns round. The power may be conceived as applied at the extremity of the arm of a lever, equal to the radius of the wheel; and the weight as applied at the extremity of a lever, equal to the radius of the axis; only those arms do not meet at one centre of motion as in the lever, but in place of this centre we have an axis of motion, viz. the axis of the whole machine. - * <^. Axis, in Optics: Optic axis, or visual axis, is a ray passing * the centre of the eye, or falling perpendicularly on the eye. Axis of a Lens, or Glass, is the axis of the solid of which the lens is a segment. Or the axis of a glass, is the line joining the two vertices or middle points of the two opposite surfaces of the glass. Axis of a Magnet, is a line passing through the middle of a magnet lengthwise, in such a manner as that, however the magnet is divided, provided the division is made according to a plane in which such line is found, the magnet will be cut or separated into two loadstones; and the extremes of such lines are called the poles of the magnet. AZIMUTH, an Arabic term in Astronomy, signifying an arc of the horizon intercepted between the meridian of the place, and the vertical circle passing through the centre of an object, and is equal to an angle of the zenith, formed by the said meridian and vertical circle, which is measured by the fore- mentioned arc. The Azimuth is reckoned eastward in the morning, and westward in the afternoon, and is usually esti- mated to the north or south, as it is nearer to one or other of those points: thus, if it be found that the vertical circle which passes through the zenith, intersects the horizon exactly between the east and the south, then the star's azimuth is said to be 45° eastward of the south; or it is the complement to the eastern or western amplitude. To find the Azimuth, at the Time of the Equinox, trigonome- trically, Say, - * - As radius is to the tangent of the latitude, So is the tangent of the altitude of the sun or star To the cosine of the azimuth from the south. To find the azimuth of a sun or star at any other time, the reader may consult any elementary treatise on astronomy, Magnetical AZIMUTH, an arch of the horizon contained-be- tween the azimuth circle of the celestial object and the magne- tical meridian ; or it is the apparent distance of the object from the north or south point of the compass. This is found by observing the object with an azimuth compass, when it is about 10° or 15° high, either in the forenoon or afternoon. Azi Muth Compass, fig, 125, is a compass used at sea for find- ing the sun's magnetical agi- muth; or, more properly, to take the bearing of any celestial ob- ject, when it is ini or above the horizon, in order to find from the magnetical azimuth, or am- plitude, the variation of the needle. The object is viewed through the upright slits or sights, and the bearing is read off on the card, which is divided into degrees, &c. 84 A z U. A Z U DICTIONARY OF MECHANICAL | SCIENCE. * Azimuth Circles, called also vertical circles, are great cir- cles of the sphere, intersecting each other in the zenith an madir, and cutting the horizon at right angles. - AzîMUTH Dial, is a dial whose stile, or gnomon, is at right angles to the plane of the horizon. AZURE, in a general sense, the blue colour of the sky; in Painting, a fine blue colour extracted from cobalt and lapis lazuli; but the colour extracted from the latter, is called ultra- marine. See Colours. - Azure, in Heraldry, the blue colour in the arms of any per- son below the rank of a baron. In the escutcheon of a noble- man it is called sapphire, and in that of a sovereign prince Jupiter. In Engraving, this colouris expressed by lines, drawn horizontally. . This colour."may signify justice, perseverance; and vigilance; when compounded with B. B A C BAc, in Navigation, a praam or...ferry boat; in Brewing, a beer cooler, a large shallow tub ; in Distillery, fermenting tubs, are called bacs. liquor-bacs, underbacs, coolers, mashtubs, working tuns, &c. BACCHARIS, ploughman’s spikenard. BACK PAINTING, the method of painting mezzotinto prints, painted on plate or crown glass with oil colours, thus:—the print and glass are, to be of one size: the print is soaked in water two hours or longer, till thoroughly moistened ; then put between two sheets of clean paper to be dried ; the glass is warmed gently, and covered with Strasburgh turpentine: the plate laid. on it, and rubbed down closely. Then the whole of the paper is rubbed off with the palm of the hand, but the print, like a thin film, is left upon the glass, and set by to dry. When dry it is varnished with white transparent warmish, and then coloured, or painted with oil-colours, tempered very stiffly ; the shadows of the engraving being generally sufficiently deep for the picture. - BAck-St.AFF, an instrument invented by captain Davis for a sea quadrant, and is so named because the back of the observer is turned towards the sun when using the instrument. BACK-STAYs, are long ropes extending from the top-mast heads to both sides of the ship, where they are extended to the channels. Their use is to second the efforts of the shrouds in supporting the mast when strained by a weight of sail. They are usually distinguished into breast back-stays, after back-stays, and shifting back-stays; the first being intended to sustain the mast when the ship sails upon a wind; or, in other terms, when the wind acts upon a ship sideways; the second is to enable her to carry sail when the wind is farther aft; and the third kind take their name from being shifted or changed from one side to the other, as occasion requires. There are also back-stays to the top-gallant-masts. BACON, Rog ER, a Franciscan friar, born near Ilchester, in Somersetshire, in 1214, and died in 1294. This bright luminary of the thirteenth century, was also a great linguist and gram- marian, well versed in the theory of perspective and optics, knew the use of convex and concave glasses, and is said to have been the inventor of gunpowder, at least so far as related to its explosive power: he also understood the erroneous prin- ciple of the calendar, and assigned the cause, and proposed the remedy: he possessed great knowledge in the medical art, and was an able mathematician, metaphysician, and theologist. His great learning, however, subjected him to the persecution of his ignorant brethren, who accused him of having dealings with the devil, and he was in consequence confined for ten years, during which time he is said to have prosecuted his studies with the same ardour as before, and with the greatest possible success. - f BAco N, FRANCIS, Baron of Verulam, Viscount of St. Alban's, and Lord High Chancellor of England under James I. was b9rn in 1560, and died in 1626; was one of those extraordinary geniuses, who, by giving a new direction to the study of philo- sophy, have most contributed to the advancement of the And a bac-maker is a cooper, who makes the centre of gravity. Or, ... / Cheerfulness. Argent, § Vigilance. Gules, § Readiness. . Ver, |-} Enterprise. Pur, ..: Goodness. Sab, Sorrow. \ B A L sciences. He clearly perceived the imperfection of the philo- sophy of the old school, and pointed out the only means of reforming it, by proceeding from facts to theories, and by means of experiments to the discovery of the laws of nature. The baron was not, however, immaculate in his office of chancellor; he was impeached for bribery and corruption, found guilty by his peers, and fined £40,000. Alas ! that the “prophet of arts” should have stooped to receive gifts for the discharge of his duties 1 , BAIL, is used in our common law to signify the freeing or setting at liberty a person arrested or imprisoned for any action, either civil or criminal, on surety taken for his appearance at a certain place and on a particular day. And the object of bail is to satisfy the condemnation and costs in the action, or render the defendant to prison. . In criminal cases, every defendant is not bailable, as for treason, murder, manslaughter, &c. - - BALANCE, in Mechanics, a peculiar application of the lever, in order to determine the difference or equality of weights in heavy bodies, and consequently their masses or quantity of matter. There are various kinds of balances; the principal of which, however, are the Common balance, the Bent Lever balance, the Roman balance, and the Swedish or Danish balance. Balances also receive other denominations, accord- ing to the circumstances under which they are employed, or the principles on which they act, as Assay balance, Hydro- static balance, &c. The Common BALANCE, or Scale. This instrument is too well-known to need any particular description; it consists of a lever A C, with equal arms, at the extremity of each of which is attached a scale, as D and E, and, before loading it with any weights, the whole ought to pre- serve a perfect equilibrium ; and this equilibrium must arise from an exact distribution of the weight of each arm and scale of the balance, as well as from the equal length of the former; for on this depends the accuracy of its action. The following obser- vations have been made, with regard to the accuracy of the balance :-‘‘It should rest in a horizontal position when loaded with equal weights. It should have great sensibility; that is, the addition of a small weight in either scale, should disturb the equilibrium, and make the beam incline sensibly from the horizontal position. It should have great stability; that is, when disturbed, it should quickly return to a state of rest. That the first něquisite may be obtained, the beam must have equal arms, and the centre of suspension must be higher than Were these centres to coincide, the beam, when the weights were cqual, would rest in any position, and the addition of the Smallest weight would overset the |3 A L \ N. ("IB, S. ///w/º/* ///www.cº. //o/, /a/a/ace. Zºº. 7. - º –2, 3 - - º | P. % - Mºw ºw. - º * *///º-ºoººoººo. Mºy Zºº wº. B A L B A L 85 DICTIONARY OF MECHANICAL SCIENCE. balance, and place the beam in a wettical situation, from which it would have no tendency to return. The sensibility, in this case, would be the greatest possible; but the other two requi- sites, of level and stability, would be entirely lost. The case would be even worse, if the centre of gravity were lower than the centre of suspension, as the balance, when deranged, would make a revolution of no less than a semicircle. When the centre of suspension is higher than the centre of gravity, if the weights be equal, the beam will be horizontal; and if they be unequal, it will take an oblique position, and will raise the centre of gravity of the whole, making the momentum on the side of the lighter weight equal to that on the side of the heavier, so that an equilibrium will again, take place. The second requisite is the sensibility of the balance, or the smallness of the weight by which a given angle of inclination is produced. If a be the length of the arm of the balance, and b the distance between the centre of suspension and the centre of gravity, P the load in either scale, and W the weight of the beam, the . (l, * a , a sensibility of the balance is as WGFTW)’ it is therefore greater, the greater the length of the arm, the less the distance i f between the two centres, and the less the weight with which the balance is loaded. Lastly, The stability, or the force with : which the state of equilibrium is recovered, is proportional to : (2 P + W) b, the denominator of the preceding fraction. The diminution of b, therefore, while it increases the sensibility, lessens the stability of the balance. gº 8 º' e however, increase the former of these quantities, without diminishing the latter. The above formulae are of great prac- The lengthening of a will, tical utifity, because by means of them, one balance may be made, having exactly the same sensibility and stability with another; it is only required that the ratio of the lengths of the arms should be the same with that which is compounded of the ratios of the distances of the centres of gravity and suspension, and of the weights of the beams.—A balance made by Ramsden for the Royal Society, is capable of weighing ten pounds, and turns with half a grain, or a millionth part of the weight. The a size, that the length of one inch shall weigh, four grains. descriptions of balances, given by mechanical writers, are gene- rally defective, as they do not give the values of a, b, and W, the quantities on which the merit of the balance depends, and by the knowledge of which, similar instruments might be con- structed. In some of the nicest balances, b is made variable by means of a small moveable weight.” Compound BALANce, is a combination of several balances employed in weighing very heavy bodies, as anchors, great guns, &c. * - . Bent Lever BALANce. See Plate, Balances, fig. 1. This instrument operates by a fixed weight C at the end of the bent lever A B C, supported on its axis B, in the pillar I H, having a scale E suspended from the other extremity of the lever at A. centre of motion, on which from A and C let fall the perpendi- HDraw the horizontal Hine K. B. G through B, the culars A K, C D ; then if B K and B D are reciprocally in pro- portion to the weights at A and C, they will be in equilibrio; but if not, the weight C will move upwards or downwards along the arc FG, till that ratio be obtained. If the lever be so bent, that when A coincides with the line GK, C coincides with the vertical B H, then as C moves from F to G, its momentum will increase, while that of the weight in the scale E will decrease; hence the weights in E corresponding to different positions of the balance, may be expressed on the graduated arc FG, and the whole used in the same way as the steel- yard. - - Hydrostatic BALANce, (Plate, fig. 2.) an instrument used for determining the specific gravity of bodies, whether fluid or solid: there are various constructions given to this instru- ment, but the following appears to be of all others the most accurate. V C G, is the stand or pillar of this hydrostatic balance, which is to be fixed in a table. From the top A hangs, by two silk strings, the horizontal bar B B, from which is suspended, by a ring i, the fine beam of a balance b , which is preveated from descending too low on either side by the gently springing piece tº yz, fixed on the support M. The harness is ammulated at 0; to shew distisctly the perpendicular position of the examen, by the small pointed index fixed above it. The strings by which the balance is suspended, passing over two pulleys, one on each side the piece at A, go down to the bottom on the other side, and are hung over the hook at v ; which hook, by means of a screw P, is moveable about one inch and a quar- ter, backward and forward, and therefore the balance may be raised or depressed so much. But if a greater elevation or depression be required, the sliding piece S, which carries the screw P, is readily moved to any part of the square brass rod W K, and fixed by means of a screw. The motion of the balance being thus adjusted, the rest of the apparatus is as follows:— HH is a small board, fixed upon the piece D, under the scales d and e, and is moveable up and down in a low slit in the pillar above C, and fastened at any part by a screw behind. From the point in the middle of the bottom of each scale, hang, by a fine hook, brass wires a d and a c. These pass through two 'holes m, m in the table. To the wire a d is suspended a curious cylindric wire rs, perforated at each end for that purpose: this wire r s is covered with paper, graduated by equal divi- sions, and is about five inches long. In the coraer of the board at E is fixed a brass tube, on which a round wire h l is so adapted as to move neither too tight nor too free, by its flat Thead I. Upon the lower part of this moves another tube Q, which has sufficient friction to make it remain in any position required: to this is fixed an index T, moving horizontally when the wire h l is turned about, and therefore may be easily set to the graduated wire a s. To the lower end of the wire rs hangs a weight L; and to that a wire p n, with a small brass ball g; about one-fourth of an inch diameter. On the other side, to the wire a c, hangs a large glass bubble B' by a horse- hair. Let us first suppose the weight L taken away, and the wire p n suspended from S, and, on the other side, let the bub- ble B' be taken away, and the weight F, suspended at c, in its room. This weight F we suppose to be sufficient to keep the several parts hanging to the other scale in equilibrium; at the same time that the middle point of the wire p n is at the surface of the water in the vessel 0. The wire p n is to be of such Now it is evident, since brass is eight times heavier than water, that for every inch the wire sinks in the water, it will become half a grain lighter and half a grain heavier for every inch it rises out of the water: consequently, by sinking two inches below the middle point, or rising two inches above it, the wire will become one grain lighter or heavier. Therefore, if when the middle point is at the surface of the water in equilibrio, the index T be set to the middle point a' of the graduated wire rs, and the distance on each side a' r and a's contains 100 equal parts; then, if in weighing bodies the weight is required to the hundredth part of a grain, it may be easily had by proceeding in the following manner. Let the body to be weighed be placed in the scaled. Put a weight into the scale e ; and let this be so determined, that one grain more shall be too much, and oue grain less too little. Then the balance being moved gently up or down, by the screw P, till the equilibrium be nicely shewn ato ; if the index T be at the middle point aſ of the wire rs, it shews that the weights put into the scale e are just equal to the weight of the body. By this method we find the absolute weight of the body: the relative weight is found by weighing it hydrostatically in water, as follows:—Instead of putting the body in the scale e, as before, let it hang with the weight F, at the hook c, by a horse-hair, as at B, supposing the vessel N of water were away. The equilibrium being then made, the index T standing between a' and r, at the 36th division, shews the weight of the body put in to be 1095, 36 grains. As it thus hangs, let it be immersed in the water of the vessel N, and it will become much lighter: the scale e will descend till the beam of the balance rests on the support z. Then suppose k00 grains put into the scale d restore the equilibrium precisely, so that the index T stand at the 36th division above a'; it is evident that the weight of an equal buik of water would, in this case, be-exactly 100 grains. After a like manner, this balance may be applied to find the specific:grawity of liquids, as is easy to conceive from what has been already said. ' The weight of a cylinder, of the fluid whose base is E.F and altitude AG, will disturb the equi- librium ...See GRAVITY, Specific. - - Z . 86 . B A L B A L DICTIONARY OF MECHANICAL SCIENCE. Roman BALANCE, or Steel-Yard, (Plate, fig. 3.) A B repre- sents an instrument of this kind: a the trutina, or handle, on which the beam turns ; k a ring on which the balance may be suspended on a nail or hook; f the hook on which the substance to be weighed, is hung ; c a collar or guard, by which the hook is fastened to the beam ; h a swivel; i the counterpoise. If now the body to be weighed be fastened to the hook.f. and the whole suspended by the ring k, the division on which the counterpoise is placed to maintain an equilibrium in the balance, will shew the weight of the body required ; the weight of the counterpoise i being known, and the large divi- sions 1, 2, 3, &c. equal to the distance between the centre of the balance and the screw which fastens the guard C to the shorter arm of the balance. When the body to be weighed is heavier than the divisions on the longer arm will indicate, the balance is turned the lower side upwards, and suspended on the other ring b, by which means the divisions become shorter, because the distance between the trutina d, and the screw on which the guard e moves, is less: the divisions on this side of the figure extending to 17, whereas they only extend to six on the other. The steelyard itself, and its whole apparatus, should be in | equilibrio when suspended on the ring k or b. The Danish BALANCE, is a kind of steelyard in common use in many parts of Europe, and is of very simple construction, con- sisting of a batten of hard wood, having a heavy lump K, as in the annexed figure, at one end, and a swivel hook b at the other. C A. L ſ l l Hº) 907030 B4 20 Io sº; 5 4 3 2 1 7, Wr The goods to be weighed are suspended on the hook, and the whole is carried in a loop of whipcord F, in which it is slid backward and forward till the goods are balanced by the weight of the other end. The weight of the goods is estimated by the loop on a scale of divisions, effected by a method purely geometrical:—Let A C (figures 1 and 2,) be the distance between the point A, from which the body whose weight is to be determin- ed is suspended, and C the centre * of gravity of the balance when the - weight W is not *-īTK attached to it. - From the point C draw an indefinite line CD, making an angle A CD with the line A C on which the divisions of the balance are to be marked, and through A draw another right line AN parallel to C D. Set off any equal distances C E, EF, FG, G. H., HI, &c. along the line C D : and upon A N, set off the distance A B equal to one of the equal distances, as CE, upon CD. From B as a fixed point draw lines BE, B F, BG, B H, &c. to the several points of division on CD; and they will intersect the line AC, in the points 1, 2, 3, 4, 5, &c. where the subdivision marks ought to stand in the balance, figure 1. ‘The numbers 1,2,3,4, &c. fig. 2, denote so many times the actual weight of the balance and its knobs, independent of the adven- titious weight W. Thus if the unloaded balance weigh 6 lbs, the distances marked 1,2,3,4, 5, &c. in fig. 2, would corre. spond to the subdivision marks 6, 12, 18, 24, 30, &c. in fig. 1. The truth of this construction may be easily shewn thus: Let w be the weight of the balance and knob, and W that of the body which is to be ascertained by the instrument. Then,. when the point of suspension is that marked 1, fig. 2, we have in the triangles AB 1, 1 CE, the sides A B and CE equal, also angle BA 1 = 1 C E, and B 1 A = E 1 C ; therefore these triangles are both equiangular and equilateral; consequently, A 1 = 1 C, and, by the natures of the lever, and the centre of gravity, W = w. Again, in like manner when the point of sus- pension is 2, the triangles A B2, 2 CF, are equiangular; and since FC = 2 A B, we have C2 = 2 Å 2, and W - 2 w. So also the triangles A B3, 3 C G, are equiangular; whence-be- ***... *** ... * , , , * * * *. * . . . . . * * * ..., cause C G = 3 A B, C 3 = 3A 3, and W = 3 w, and so on, through the whole division. This balance (says Dr. Gregory,) has been described more on account of its curiosity than actual utility; for in ascertain- ing large weights it would be extremely cumbersome and diffi- cult to manage. In the determination of weights not exceed- ing twenty or thirty pounds, it might, however, be rendered very manageable; for it might be about the length of an ex- ciseman's rod, or a walking stick, having a knob of lead at one end ; and in this case the divisions near the knob might be so numerous as to enable a person to weigh accurately to quarters of pounds, if not to ounces: the rod might be moved to and fro upon a chair-back, or the edge of a trussel; and thus this instrument might often be more conveniently used than a spring steelyard. Fidler's BALANce, as here represented, was made for the Royal Institution, and does not differ much from those con- - structed by Rams- den and Troughton. I. *\| The middle column A TEL-T can be raised at plea- y y sure by the nut B, and supports the round A. ends of the axis in the forks at its upper ex- tremity, in order to remove the pressure on the sharp edges of the axis within the E forks. C and D are pillars which occasion- | ally support the scales, . and may be elevated or depressed, by turning the nut E. The screw F raises or depresses a weight within the conical beam, for the purpose of regulating the position of the centre of gravity; and the graduated arc G measures the extent of the vibrations. An Improvement on this Balance, is represented below, where D C is a micrometer screw, fixed to the arm F A, so C P; II) O O O R. n . S AC iſ] D rN _ _ _ ] ºf L. I. T. S 30 2.0 L0 0 2) that when it is turned round by the nut D, it neither approaches to nor recedes from the centre of motion F. The screw DC works in a female screw, in the small weight m, and by revolv. ing in one direction carries this weight from S to R, and thus gives the preponderance to the scale G. The recession of the weight m from the centre F is measured, as in the common micrometer; and a weight a placed in the scale suspended at A, will be in equilibrio with n, placed at any distance S n, h S m × m W en * = -FR- . Proney's BALANCE Support, (Plate, fig. 4.) for balances of all dimensions, is calculated to render the operations for which these instruments, are used more expeditious and convenient, without diminishing their accuracy. - “Several experiments,” says he, “in which I was engaged during the course of the last winter, put me under the neces- sity of contriving a support which might be applied promis- cuously to every kind of balance, whether provided with a suspending handle or not, and which, without detriment to its accuracy, should afford me commodious means of successively raising and lowering it. It is well known how embarrassing and laborious the operation of weighing is, when performed with balances supported by the hand; though this is often only the smallestinconvenience with which their use is attended. “Various artists have contrived supports, commodious in B A L SCIEN C. E. B A L 87 DICTION ARY ( ; F M E(; H AN (CAL their use, and ingenious in their principle ; but as each of these supports can' only be adapted to a single balance, they become so expensive as to be out of the reach of the majority of artists and experimentalists. I think, therefore, I shall do them an acceptable service by publishing, in compliance with the request of several eminent chemists, the description of a support, which, besides the advantage of being adapted for all kinds of balances, possesses that of being constructed at a small expense, either in wood or metal. “A triangular foot of brass A a, a, a, (figs. 4, 5, repre- senting the elevation and section of my apparatus,) has its three extremities a, a, a, firmly screwed down upon a table or horizontal plane. Into the part A of this foot is screwed a cylindrical rod, A B, which may be of any arbitrary length: it may even be convenient to have two of these of different lengths, in order that they may be changed, when we wish to employ the machine for very large balances. Those which I have made use of are, the one half a metre, and the other one metre (39.4 inches) in length. “A vertical pulley, P, is placed at the top of the stem A B, in such a manner that the same vertical plane passes through the axis of the rod, and through the horizontal axis of the pulley; the block or collar CD of this pulley has at its lower part a tube C B, into which enters, with a gentle friction, the superior extremity of the rod A B; a screw, E, serves to keep the pulley in a fixed position. “Another pulley, P, fig. 5, is fixed at the bottom of the rod A B, in such a position that the tangent or cofd of the pulleys P and P is parallel to the axis of the rod A. B. “A cord Kt pH G PF, to the end of which is suspended on the outside of the vertical table K a small weight k, passes through a hole t made in the foot a, rolls over the pulleys and P, and is attached at F to a piece in m' n q, which has the form of a fork, and to which are suspended (as I shall shortly explain) the balance, the weights, and the substances that are to be weighed. Fm is a button, which being screwed at the top of the fork, receives the end of the cord, and by means of a knot made on it sustains the fork. “The tail or handle of this fork is of a prismatic form at the part m' n; this prismatic part enters a groove ffmade at the extremity N of the horizontal piece N O, so that it can slide freely in this groove either upwards or downwards, its course being, however, limited at m', where it is stopped by the enlarged handle of the fork, and at n by the greater width pro- duced by the separation of the two branches of the fork. “The piece N O, which is hollow, and intersected at O by the stem A B, can slide along and turn round this stem : when it is brought to its proper height, it is secured by means of the screw V, and it is then necessary, first, that it should be at such a height, that, when the stop m rests on the side of the groove ff, or when N O can move no further down, the scale of the balance shall be in contact with the table or horizontal plane, in order that we may afterwards be able to raise it the whole height offm; secondly, that the cord FF be in one and the same vertical plane with H. G. “The groove at N ought to be situated in such a manner that the axis of the prismatic part of the tail of the fork, and the cord FF", shall always be in the same vertical plane, or in a parallel line with the axis of the stem A B. “These dispositions being made, let us imagine the two branches n g of the fork to be perforated with holes of different diameters, in order to receive horizontal pins (g g) of different sizes; and we shall have all that is requisite for the ordinary operations of weighing, performed, in the air with balances, the beams of which are suspended from above. - “In fact, whatever kind of balance we use, we are to intro- duce the extremity of its suspending handle into the fork n q, and insert into the round hole, which the handle of the balance always has at its superior extremity, any one of the pins that will enter with ease; we then apply the piece O N in such a manner as to fulfil the conditions above laid down for the position of this piece; after which, it is to be fixed by the screw W. This being done, the scales of the balance are to be charged, which being in contact with the table, or horizontal plane, can have no motion. When the scales are charged, we lay hold of the small ball k, and draw the cord which suspends it so as to raise the balance very slowly: if the scales be not in equilibrio, the cord is to be loosened till they rest again upon the table, and so successively. “A counterpoise, Q, suspended to the cord FG, ought to preserve the equilibrium with the weight of the balance. By means of this precaution it comes to pass, that the common centre of gravity of all the forces supported by the pulley P, falls in all cases upon the axis of the stem A B, which thus has : no tendency to bend. “If we wish now to use a hydrostatic balance, we adapt to the stem A B a small board O'N' which, by means of a cylindrical hole at O', may slide along the K rod A B, and be fixed at any arbitrary TN height by a screw at V’. Another piece, O or board K' K', is placed upon V’ N', in such a manner that the holes TT corre- spond with the centre of the scales, un- der which are placed the hooks intended for holding the substances suspended in the water, and K' K' is fixed upon V'N by means of screws W’. oTo || @ “These arrangements being made, let N. Oğ Vº the piece N’ O’ and the board K. K., be O O placed in such a manner that, first,the whole - ©|-ſ dº height of the balance be placed between this piece and the board, and that scales L L be in contact with the board K'K', their centres corresponding with holes made in TT. Secondly, that K'K' be sufficiently elevated to enable us to place under it the vessels W W, filled with water, and con- veniently to immerse, in one of these ves- sels, the substances which we wish to weigh hydrostatically. “According to the common practice, these substances are suspended by a very thin wire; but by placing, after my method, two vessels, and suspending to the two scales wires of equal diameter, the one of which supports the substance that is to be weighed, and the other merely in part immersed, the magnitude of the diameter will have no influence upon the accuracy of the operation; for, let us suppose the apparatus to be adjusted in such a manner that at first the two wires were in equilibrio with each other, (which may easily be obtained by varying the height of the water in the vessels,) these two wires will still be in equilibrio, when the beam FF" being elevated, will remain in its horizon- tal position: whence it follows, that if one of the wires have suspended from it a substance innmersed in the water, and we place in the opposite scale, and consequently out of the water, a weight adequate to keep the equilibrium with the immersed substance, for a horizontal position of the beam, the equili- brium will still be maintained, whatever may be the elevation or depression of the beam, provided it continue in a horizontal position; for the lengths of the wires, either above or below the surface of the water, being equal, the difference between the specific weight of the water and that of the metal will operate equally upon both extremities of the beam. It is evident that this advantage will not be obtained if we employ only the wire to which the substance is suspended, and that the equilibrium, established for a certain elevation and a hori- zontal position of the beam, will not apply to other elevations of the beam by preserving it in the horizontal position. ×. “It is to be remarked, that my method compensates not only for the excess of the specific weight of the wires over that of the water, but also for that which depends upon the adhesion of the fluid to the wires, and the covering of water which they carry along with them. “All that has been said hitherto applies only to balances that are provided with suspended handles; but, in order to render this support absolutely universal in its use, it was neces- sary that it should be possible to adapt it to a beam which had nothing but its centres; for which purpose I contrived an apparatus, which is suspended, like those of a common balance, to the fork n q, and which may receive the centres of any beam. The engravings in the plate represent it provided with this apparatus, the construction of which is as follows. 88 B A L B A L DICTIONARY of MECHANICAL SCIENCE. “A piecess' fig. 6, has a screwed hole bored into it at s’, into, which the screwdd is inserted half its length. Another hole, made at s, in a perpendicular direction to the first, receives the ping y, to which all the inferior apparatus is suspended. This hole s supplies the place of that which is found at the upper extremity of the suspending handle of balances. “The two other vertical pieces r, r, (fig. 6 and 7,) have at their upper part cylindrical holes not screwed, in which the screw did can turn freely. These superior parts are placed at an arbitrary distance, and retained in their situation by means of four nut-screws u, u, u, u, each of the pieces being fastened between two of these nut-screws. A cylindrical rod h h tra- verses the inferior parts of these pieces r, r, and is fixed there by means of nut-screws, in such a manner that the superior and inferior points of the piece r r are invariably at the same distance. “Each of these pieces r, r has, upon the surface which is perpendicular to the direction of d d and h h, a groove e e, and a circalar aperture X, having at its lower part a small bracket of polished steel a a, intended to support one of the centres of the beam. Into the upper part of the grooves e e a rule e'e' is introduced, which must enter with tightness, and which, with the pieces did and hk , give such a solidity to the apparatus, that the adjustment of its parts cannot be in the smallest degree deranged. The remainder of the groove which is not occupied by e'e', ought to be of a length somewhat greater than that of the largest cock or index adapted to the beams which we shall have to use. “The method of using the apparatus which I have just described is very simple. The beam which we intend to employ is placed between the two branches r, r, which are removed from each other till the centres can be brought oppo- site to the circular holes X; the pieces r, r are then brought together in such a manner that the centres enter these holes X, and so as still to leave some room for motion between these pieces and the body of the beam, in order that the oscillations of the balance may be perfectly free. The pieces r, 7', are brought parallel with each other, and the adjustment of the apparatus is rendered perfectly firm, by means of nut-screws, by the small cylindrical rod h h, and by the rule e'e'. The apparatus being adjusted in this manner, it is suspended to the fork n q, by inserting the pin g g into the hole s, and the balance is used in the manner that has already been explained. We know the equilibrium to be established, and the beam to be horizontal, when the index y y divides the breadth of the space ee into two equal parts; but, in order to ascertain the circumstances with greater accuracy, I have attached to the rule e'e' a plummet, eli', by means of which we may distinguish , the slightest deviations of the index from the perpendicular direction.” - 4. - . BALANce of a Clock, or Watch, is that part which by its motion regulates and determines the beats. . The circular part of it is called the rim, and its spindle the verge ; there belong to it also two pallets or huts, that play in the fangs of the crown-wheel: in pocket watches, that strong stud in which the lower pivot of the verge plays, and in the middle of which one pivot of the crown-wheel runs, is called the potence : the wrought piece which covers the balance, and in which the upper pivot of the balance plays, is the cock; and the small spring in the new pocket watches is called the regulator. . The motion of a balance, as well as that of a pendulum, being reciprocating, while the pressure of the wheels is constantly in one direction, it is obvious that some art must be äsed to accommodate the one to the other. When a tooth of the wheel Jhas given the balance a motion in one direction, it must quit it, that it may get an impulsion in the opposite direction. The balance or pendulum thus escaping from the tooth of the wheel, or the táoth escaping from the balance, has given to the gene- ral construction the name of scapement among our artists. See Scape MENT, - Dr. Gregory observes, that some of the most important pro- positions relative to watch balances may be concisely stated as follows: 1. The balance of a watch is analogous to the pendu- lumin its properties and use. The simple balance is a circu- lar annulus, equally heavy in all its parts, and concentrigal with the pivots of the axis on which it is mounted. This taining power. . balance is moved by a spiral spring called the balance spring, the invention of Mr. Hook. 2. The pendulum requires a less maintaining power than the balance. Hence the natural isochronism of the pendulum is less disturbed by the relatively small inequalities of the main- 3. The elastic force of the spring which impels the circum- ference of the balance is directly as the tension of the spring; that is, the weights necessary to counterpoise a spiral spring’s elastic force, when the balance is wound to different distances from the quiescent point, are in the direct ratio of the arcs through which it is wound. - - $ - 4. The vibrations of a balance, whether through great or small arcs, are performed in the same time. For the accelerating force is directly as the distance from the point of quiescence: hence, therefore, the motion of the balance is analogous to that of a pendulum vibrating in cycloidal arches. - 5. The time of the vibration of a balance is the same as if a quantity of matter, whose inertia is equal to that by which the mass contained in the balance opposes the communication of motion to the circumference, described a cycloid whose length is equal to the arc of vibration, described by the circumference, the accelerating force being equal to that of the balance. 6. The times of vibration of different balances are in a ratio . compounded of the direct subduplicate ratios of their weights and semidiameters, and the inverse subduplicate ratio of the tensions of the springs, or of the weights which counterpoise them, when wound through a given angle. . . . . 7. The times of vibration of different balances are in a ratio compounded of the direct simple ratio of the radii and direct subduplicate ratio of their weights, and the inverse subduplicate ratio of the absolute forces of the springs at a given tension. 8. Hence the absolute force of the balance spring, the diame- ter and weight of the balance being the same, is inversely as the square of the time of one vibration. 9. The absolute force or strength of the balance spring, the time of one vibration, and the weight of the balance, being the same, is inversely as the square of the diameter. 10. The weight of the balance, the strength of the spring, and time of vibration, being the same, is inversely as the square of the diameter.—Hence, a large balance, vibrating in the same time with the same spring, will be much lighter than asmall one. 11. If the rim of the balance be always of the same breadth and thickness, so that the weight shall be as the radius, the strength of the spring must be as the cube of the diameter of the balance, that the time of vibration may continue the same. 12. The momentum of the balance is increased better by increasing its diameter than its weight. . b 13. The longer a detached balance continues its motion, the better. * 14. The greater the number of vibrations performed by a balance in a given time, the less susceptible is it of external agitations. - 15. Slow vibrations are, to a certain extent, preferable to quick vibrations: but there is mariifestly a himit; for if the vibrations be too slow, the watch will be liable to stop. 16. A balance should describe as large arches as possible, as suppose 240°, 260°, 300°, or an entire circle.—First, because the momentum of the balance is thus increased ; and therefore the inequalities in the force of maintaining power bear'a less proportion to it, and Öf consequence will have less influence. 2dly. The balance is less susceptible of external agitations. 3dly. A given variation in the extent of the vibrations produces a less variation in the going of the machine. But care must be taken that in these great vibrations, the spring shall neither touch any obstacle, nor its spires touch each other in contracting. 17. The time of the vibration of the balance is increased by heat, and diminished by cold.—First, because the length of the spiral spring is increased by heat, and therefore its force dimi-. nished; and the contrary by cold. 2dly. The diameter of the balance is increased by heat, and ºtherefore also the time of vibration.; and the contrary by cold. . . . . 18. That balance is the most perfect, which, without the com- pensation of a thermometer, is most subject to the influence of heat and cold. Because the obstructions from oil and friction act as a compensation to the expansion or contraction of the B. A. It B A L 89 DICTIONARY OF MECHANICAL SCIENCE. spring, and balance; therefore that balance; which is most affected is most free from the influence of oil, and friction.... . . 19, The errors in the going of a watch, arising from the change of temperature, may be corrected by varying, the length of the balance spring. Nevertheless, as it is extremely difficult to form an isochronal spiral, any variation in its length is dam- gerous, because we shall thus, probably lose that point which determines its isochronism. . . * variation of temperature, may be corrected by varying the diameter of the balance. - . This may be effected by a peculiar contrivance, which has two different metals which possess different degrees of expan- sibility, as brass and steel, for instance; of which two metals sion, in like elevations of temperature, is nearly as 2 to 1. For, according to Smeaton's experiments, the corresponding expan- expansions being occasioned by a change from a medium tem- perature to that of 180° of Fahrenheit's thermometer. One of exhibited in the figure annexed, and is thus generally de- scribed: The outer part of the rim is brass, and the inner part steel. After this compound rim is brought to its figure by three places A, B, C, which sets ID - - one end of each third part of the periphery at liberty to . “A move outwards when the tem- Iliff===l- }) IC . ] wards when it is increased. | D, E, F, are three similar and upon the circular bars in a pro- per manner to admit of their - being fixed at any required dis- ºr tance from the extremity, where T n heads of which may be set nearer to, or further from, the centre, and serve as weights to effect the adjustments for position and as follows: when an increase of heat diminishes the elastic force of the pendulum spring K, the outer brass rim being nearer to the axis, and diminish the effect of the inertia of the balance, which consequently is as speedily carried through its adds to the elastic force of the spring, the same weights are also thrown further out, and prevent the acceleration which found by trial of the going of the machine: if it gain by heat, the weights do more than-compensate, and must be moved but if the gain be produced by cold, the spring predominates, and the weights will accordingly require to be set further out. house or other building, supported by pillars or consoles, and encompassed with a bulustrade or rail... lately been invented by J. Dennett of Newport, Isle of White, with a view of assisting sailors: in baling vessels when the too high an opinion of Buchanan's pump, the chain pump, and several other hydraulic engines, to fancy the apparatus before we give it the reader, with the following decription: A and B are parts of the hatchways of the upper and position, reaching from a little above the coamings of the upper deck to the ballast in the hold, and attached to the lower on the rebate of C C ; its bottom is a flap valve, so that when it slides down into the water it opens, the bucket fills 20. The errors in, the going, of a watch, occasioned by the obtained the mame of the eaſpansion balance, being composed of it has been observed, that the increase of dimensions by expan- sions of hard steel and brass wire are as 147 and 232, the the most approved constructions of an expansion balance, is turning, it is cut through in (2-4 perature is diminished, or in- - NS-5 equal masses of metal, fitted T the motion is most considerable. G, H, I, are three screws, the rate. The peculiar advantage of this balance may be explained lengthened more than the steel, must throw the weights D, E, F, vibration as before... And, on the contrary, when cold weather would have followed. The exact adjustment of the weights is further from the extreme ends of the circular compound bars; BALCONY, in Architecture, a projection in the front of a BALING of SHiPs. ... An apparatus for this purpose has pumps from accident get out of order. We confess, we have us will ever become very general; but such as the invention is, lower decks. C C is a long rebated slide, in an inclined hatchway by a block, D. E is a square bucket, made to slide instantly, and closes upon being drawn up full of water, without any attention on the part of the workmen. The upper portion F of the re- bate of the long slide is made detached, and is fixed in its place by the pin G, on which it turns as on an axis. The bucket is shewn discharging the water on the upper deck, and when the rope H I K is let go, the bucket falls down, rights itself, and the upper portion F, of the slide, fall- ing down with it, and join- ing the lower part, the buck- et runs down the whole of the slide into the water, is instantly filled, and drawn up again by pulling the parts IK of the rope, the part K having passed through a block, M, on the deck. A pin is fixed in the top of the rebate, so that when the ... bucket rises up, and is only in the loose pºrtion F, it is stopped by the pin, and the 1 loose portion F, by farther pulling, rises out of its - place, and upsets the bucket. To prevent the bucket from being pulled higher up than is requisite to discharge the water, a knot is worked in the rope which stops the block at L. The block L is made fast to any yardarm, and the upper end of the rope K is secured to the same, or elsewhere, just length enough to let the bucket reach the foot of the slide. BALL, in the Military art, comprehends all sorts of bullets for fire-arms, as cannon balls, which are made of cast-iron; musket bullets, which are cast from lead. See GUNNERY. BALL and Socket, an instrument made of brass, with a per- petual screw, or so as to move horizontally, vertically, or obliquely, and is generally used for the managing of surveying of astronomical instruments. BALL, in a popular sense, is any spherical body, whether natural or artificial. Fire BALLs, in Meteorology, are luminous bodies generally appearing at a great height above the earth, and sometimes amazingly vivid and brilliant. See METEOR. BALLAST, a certain portion of stone, iron, gravel, or such like materials, deposited in a ship's hold, when she has either no cargo, or too little to bring her sufficiently low in the water, and is used to counterbalance the effect of the wind upon the masts, and give the ship a proper stability, that she may be enabled to carry sail without danger of overturning. The art of ballasting consists in placing the centre of gravity so as neither to be too high, nor too, low, too far forward, nor too far aft, and that the surface of the water may nearly rise to the extreme breadth a-midships, and thus the ship, will be enabled to carry a good sail, incline but little, and ply well to windward. Shingle Ballast, is ballast of coarse-gravel. BALLISTA, a machine used by the ancients for shooting darts; which resembles our crossbow. The annexed figure, repre- sents, one of these engines used in sieges: 2,2 the base of the ballista; 3,4, upright beams; 5,6, transverse beams; 7,7, the two capitals which cannot be seen in this transverse figure; 9,9, two posts or supports for strengthening the transverse beams; 10,10, two skains of cords fastened to the capitals; 11,11, two arms inserted between the two stands, or parts of the skains; 12, a cord fastened to the two. arms; 13, darts which are shot by the ballista; 14,14, curves in the upright beams, and in the concavity of the cushions, are fastened in order to break the force of the arms, which strike against them. with great force when the dart 15 is discharged; 16, the arbor of the machine, in which a groove or canal perfectly straight is formed, and in which the darts are placed in order to be shot by the ballista; 17 the nut of the trigger; 19, a hook by which 2 A 90 b A M B. A. N. DICTIONARY OF MECHANICAL SCIENCE. the chord is drawn towards the centre, and the ballista cocked 20, a stage or table, on which the ballista is in part sustained. 3. / 14. - 19 12 1S 2. |S N Vegetius informs us, that the ballista discharged darts with such rapidity and power, that nothing could resist their force; and Athaenaeus adds, that Agistratus made one, of little more than a cubit and a half, which shot darts 500 yards. Balist A, was formerly also the name given to the cross-staff. BALLISTIC Pendulum, an ingenious machine, invented by Robins, for ascertaining the velocity of military projectiles, and consequently the force of fired gunpow- der. It consists of a large block of wood S MN, suspended vertically by a strong hori- zontal iron axis at S, to which it is connected by a firm iron stem. Now, to determine the velocity with which a ball is projected, the pendulum is so situated that the ball.im- pinges directly against it, and causes it to vibrate through a certain arc, which being accurately observed, the velocity of projec- M N tion is thence computed. Dr. Hutton made many experiments of this kind, by discharg— ing cannon-balls at various distances from - the pendulum; from which is deduced a complete series of the resistances of the air to balls passing through it, with all degrees of velocities from 0 to 2000 feet per second. BALLOON, AIR. See AERostation. Le Ballon Aerostatique, the Air Balloon, was placed among the constellations by M. de Lalande, a few years back. It is immediately south of the Zodiacal Goat, west of the Southern Fish, north of Microscopium, and east of Sagittarius. BALLOTADE, in the Manage, the leap of a horse between two pillars, or upon a straight line, made with justness of time, with the aid of the hand and the calves of the leg, so that when his forefeet are in the air, he shews nothing but the shoes of his hind feet without jerking out. BALLUSTRADE, a series or row of ballusters, joined by a rail, serving as well for a rest to the elbows, as for a fence or enclosure to balconies, staircases, altars, &c. BALM, a well-known plant, that thrives well in light rich soil, and increases freely by dividing the root. It grows well under the shade of trees, and is a handsome ornament to every flower-garden or cottage. In a fresh state, balm smells some- thing like a lemon, and has a weak rough aromatic taste. On distilling the herb with water, it impregnates the first runnings pretty strongly with its grateful flavour. Prepared as tea, it makes a grateful diluent drink in fevers; and in this way it is commonly used, either by itself, or tempered with lemon juice. The Balsam of Tolu, from a region on the north coast of South America near the isthmus of Panama, is a resinous fluid, obtained from a tree of the same name by incisions in the trunk, and is useful in medicine both as a tincture and a syrup; it has an agreeable flavour resembling balm, and, made into lozenges, appeases the irritation occasioned by severe coughing. BAMBOO, a plant, which sometimes grows forty feet high. Its young shoots and roots make an Indian pickle; its light graceful knotted stalk serves, not only in the East for the con- struction of houses, but for furnishing them with almost every utensil. Tables, chairs, bedsteads, bedding, barrows, fences, sacking, cordage, oakuma, candle-wicks, paper, whips, &c. are made from bamboo in China. In Malabar, the bamboos are trained over iron arches, and when they have assumed the curve of the mould, are used for roofs to palanquins, and sell at five or six hundred rupees a set. Might not thousands of cottagers in our own country make money by training the willow, the ash, the hazel, and many other trees and shrubs, into similar arches, for innumerable purposes in common life? The Chinese BAMBoo HABIT, to save shipwrecked persons from drowning, consists of four pieces of bamboo, about a man's length, placed horizontally and at rightangles, in parallel pairs, and tied firmly at the four corners; the opening being just sufficient to allow the head and shoulders to get through, as represented in the figure, and then tied securely to the body of the person using it. Deal will make this habit equally well. BANANA, a valuable West India plant, whose leaves are six feet long and one foot broad, and the fruit about five inches long, and in shape resembling a cucumber, with a soft luscious pulp, is frequently introduced in desserts, or formed into small loaves, by squeezing out the juice, and leaving it to dry. BANGLE EARs, an imperfection in a horse, remedied by placing his ears in such a manner as you would have them stand: Bind them with two little boards so fast that they cannot stir, and then clip away all the empty wrinkled skin close by the head. BANGUE, a species of opiate, in great use throughout the East for drowning care and inspiring joy, is extracted from the leaf of a kind of wild hemp, that grows in the countries of the Levant. The leaves are dried in the shade, ground to pow- der, and made into pills or conserves, or taken as a powder. The Turks take this deleterious drug and opium as substi- stutes for wine, which is forbidden by the Koran to all true Mussulmans. BANIAN TREE, the arched Indian Fig, or God Tree, so named, perhaps, because the Hindoos plant it near their tem- ples, or where no temple exists: the tree itself is made use of for that purpose. The branches of this famous tree descend, take root, and in time are converted into great trunks, so that a whole tree, with all its props, may cover a space of 2000 feet in circumference. B. A. R. B A. R. 91 JDICTIONARY OF MECHANICAL SCIENCE. BANN, proscription or banishment for a crime proved; hence, to put a prince under the bann of the empire, is, by sound of trumpet, to declare him divested of all his dignities.— Episcopal BANN is a fine paid to the bishop by those guilty of sacrilege, or other crimes.—The Papal BANN is excommunica- tion.—In Military affairs, a proclamation by beat of drum or sound of trumpet. . . . BANQUET, in Fortification, a platform or bank of earth, upon which soldiers stand within the parapet, to fire upon an enemy in the ditch or covert way. . . - BARBACAN, or BARBICAN, an outer defence or fortification to a city or castle, especially a fence to the city or walls. See. CAstle. A fort at the entrance to a bridge, &c. BARBE, in Military Tactics, means to fire the cannon over the parapet, instead of firing through the embrazures or port- holes. -: , , BARBLES, or BARBs, knots of superfluous ſlesh growing inside the mouths of cattle, and which are cut or burned off, to enable the animals to eat their food. * x BARILLA, is the Spanish name of a plant, from the burnt ashes of which is produced a salt called hali or soda, hard solid masses of a bluish tinge, very heavy, sonorous, dry to the touch, corrosive to the taste, and strongly saline, employed chiefly in the manufacture of glass and soap. - - BARK, in Botany, the skin or covering of plants, shrubs, and trees: as oak bark, which is used in tanning; Jesuit's bark, (cinchona,) in physic; as also maee, alder, and walnut tree bark, in dyeing; other barks are used in spiceries, as cinnamon, cassia lignea. Cork bark is a valuable and useful product. In India and the South Sea islands, cloth is fabricated from the bark of trees. - - BARK Stove, or Moist Stove, is a hothouse containing a pit or mass of bark, earth, sand, or other matter, in which the pots containing the plants are plunged, or the plants them- selves, planted. This house is heated from below, or by the fermentation of the bed of materials, as well as by the atmo- sphere of the house; and it is used solely for raising and culti- vating flowers. The bark-stove floriculture house at Frog- more is truly magnificent. Such houses should be built east and west, though those of the botanic gardens of Dublin and Liverpool are placed with their gables to the south. Loddige's immense palmhouse at Hackney is glazed on all sides. BARLEY, a well-known grain or corn, used for making malt, meal, bread, or soups; and sugar boiled in barley water is barley sugar, which is rolled on a stone anointed with oil of sweet almonds, and formed into twisted sticks. Whiskey, made of malt, is distilled by a very common chemical process. The malt is dried, mashed, boiled, and from the liquor thus made, the alcohol, or pure spirit, is distilled. Proof spirit con- sists of half water and half pure spirit; that is, such as when poured on gunpowder, and set on fire, will burn all away, and permit the powder to take fire and flash, as in open air. But if the spirit be not so highly rectified, there will remain some water, which will make the powder wet, and unfit to take fire. Proof spirit of any kind weighs seven pounds twelve ounces per gallon. . * BARM, Yeast, first used by the Celtes in making bread. See BREAD. * . . . . " . . BAROMETER, an instrument to measure the elasticity of air; consists of a hollow glass cone, filled with mercury, and hermetically sealed at the end, so that no air be left in it, as represented in the following figure. When it is set upright, the mercury descends down the tube, into the bubble, which has a little opening at the top, that the air may have free ingress and egress. At the top of the tube there must be a perfect vacuum. The instrument is fixed in a frame, and hung perpendicular against a wall. Near the top, on the frame, is placed a scale of inches, shewing how high the mercury is in the tube, above the level of it in the bubble, which is generally from 28 to 31, inches, but mostly about 29 or 30. Along with the scale of inches, there is also placed a scale of such weather as has been observed to answer the several heights of the quicksilver. In dividing the scale of inches, care must be taken to make proper allowance for the rising or falling of the quicksilver in the bubble, which ought to be about half full when it stands at 29}, which is the mean height; for, whilst the quicksilver rises an inch, it descends a little in the bubble ; and that descent must be deducted, n which makes the divisions be something less than _|32 an inch. These inches must be divided into tenth – parts, for the more exact measuring the weight of the atmosphere: for the pillar of mercury in the tube is always equal to the weight of a pillar of the atmosphere of the same thickness; and, as the height of the quicksilver increases or decreases, the weight of the air increases or decreases accordingly. The tube must be near 3 feet long, and the bore not less than } or ; of an inch in diameter, or else the quicksilver will not move freely in it. - The real cause of the suspension of the mer- cury in the tube, and of water in pumps, is now generally admitted to be the atmospheric pres- C sure, and repeated observations which have been Č D made, connected with this subject, discover that F. the column of mercury varies considerably in its height, at different times, and this variation has 19 D been observed to be followed by changes of the weather. This, in the infancy of meteorological Science, led to farther and more accurate observations, and various alterations and improvements were suggested in the construction of the barometer, or weather-glass. . . The constructions of this instrument are now exceedingly varied and numerous, much beyond what our limits will admit of enumerating ; we must, therefore, content ourselves with describing the most popular and general forms, and refer the reader who wishes for farther information to the article BARo- METER, in Rees’s Cyclopedia, where he will find a detailed account of nearly all the forms and uses to which this instru- ment has been applied. Common BARometer.—This is represented in the figure above, such as it was invented by Torricelli. A B is a glass tube open at one end, and hermetically sealed at the other, A, having its diameter about one-third or one-fourth of an inch, and its length thirty-three or thirty-four inches: this is filled with purified mercury so justly as not to have any air over it, nor any bubbles adhering to the sides of the tube, which is best done by means of a small paper or glass funnel, with a capillary tube. The orifice of the tube, filled after this manner, so as to overflow, is then closely pressed by the finger, so as to exclude any air between it and the mercury; this done, invert the tube, and immerse the finger and end, thus stopped, into a bason of like purified quicksilver, and in this position withdraw the, finger, and the mercury will descend in the tube to some place, as E, between twenty-eight and thirty-one inches above the surface of the mercury in the bason at F ; these being the limits between which it always stands near the surface of the earth or sea. Instead, however, of the detached vessel CD, the modern barometer tubes are curved at the bottom, and termi- nate in a bulb, which ought to be as big as it can be conveniently made, in order that the variation in the altitude of the mercury in the tube may affect, as little as possible, the depth of that in the bulb. - The barometer tubes, under either of the above forms, are now to be enclosed in a wooden case or frame, to prevent their being broken, and the vessel or bulb, though open to the air, must be secured from dust; and thus far the construction will be completed. ... • . * Next, measure from the surface of the mercury at F, 28 inches to G, and 31 inches to H.; dividing the spaces between them into inches and tenths, which are marked on a scale placed against the side of the tube; and these tenths are again subdivided into hundredth parts of an inch, by means of a sliding index carrying a vernier or monius. In the common barometers called weather-glasses, the lowest limit at G is marked stormy, and the highest point, H, is marked on one side very dry for summer, aud on the other, very hard frost for winter. To the next half-inch below the highest point are annexed set fair on the one side, and set frost on the other. At the height of 30 inches, fair is marked on one side, and frost on the other. At the height of 29% inches is marked changeable, both for summer and winter; and at 29 inches, rain on one ; * F B. A. R. B A. R. DICTIONARY OF AMECHANICAI, SCIENCE. side, and snow, on the other, At 28% inches, much rain on one side, and much snow; on, the other; the lowest division, being marked stormy, as we have before observed. - The barometer is advantageously employed in measuring the heights of mountains; and for every 103 feet perpendicular that the instrumentis carried up a mountain, the mercury falls l-10th of an inch; 103 feet of air being equal to 1-10th of an inch of mercury, on the surface of the earth : that is, to one degree in the scale of the barometer. Thus, on the top of Snowden, in Wales, the mercury sinks 3:67 inches, therefore that mountain is 3720 feet high. - A thermometer should always be attached to the barometer, and by the side of it a scale of correction, to shew how much to add or subtract from the height of the mercury in the baro- meter, for the degree of temperature; for it is evident, that the mercury in the tube will be affected by heat and cold in the same manner as the thermometer, and, on that account, it will not shew the true weight of the atmosphere. For, by numerous experiments it has been found, that air expands about ºth part of its bulk for every degree of heat, and contracts the same for every degree of cold, and consequently, the result obtained from the above formula must be increased or dimi- nished by as many times #3th part of itself, as the temperature in degrees exceeds, or is less than, 319. Hence 'we have another rule for measuring altitudes by the barometer, viz. Observe the height of the mercury at the bottom of the object to be measured, and again at its top ; as also the degree of the thermometer in both these situations; and half the sum of these two last may be accounted the mean temperature. Then multiply the difference of the logarithms of the two heights of the barometer by 10,000, and correct the result by adding or subtracting so many times its 435th part, as the degrees of the mean temperature are more or less than 319; and the last number will be the altitude in fathoms. Example.—If the heights of the barometer at the bottom and top of a hill are 29.37 and 26'59 inches respectively, and the mean temperature 26°, what is the height? Log. 29.37 = 1.467904 Log. 26'59 = 1.424718 0.043186 10000 Difference of Logs. = Multiply by 431 '86 Now 319 – 26° = 5° temperature below 319; therefore is of 431'86 = 496; consequently 431'86 – 496 = 426.90 fathoms, the altitude of the hill. - This requires, however, certain modifications, on account of the difference in low and elevated situations, the expan- | sion of the column of mercury, and other circumstances, which the limits of our article will not admit of investigating. Before M. de Luc began his experiments with the barometer, a mean of the two temperatures shewn by the thermometer attached to the barometer, and the height of the barometer, at the bottom and top of a hill, were thought sufficient for determining its altitude. De Luc, however, found that an additional or detached thermometer was also necessary; and this has been since confirmed by the experiments of General Roy and Sir G. Shuckburgh. The formulae for the height in fathoms, according to the two latter observers, are as follow: R.O.Y. $10000 l = 468 d? x {1 + (f- 32°) 00245; SH UCKBURGH. $10000 l = 440d: x {1 + (f- 32°).00243; Where l = diff. of logs. of the heights of barometer, d = diff. of degrees Farhenheit's thermometer, f = mean of the two temperatures shewn by the detached thermometer exposed for a few minutes to the open air in the shade of the two stations. The sign — takes place when the attached thermometer is highest at the lower station, and the sign + when it is lowest at that station. Example.—Find the height of a mountain, from the following observations taken at the foot and summit: & - - Barom. . . Attach. Thermiº Detach. Therm. - - Lowest station, 29:862 '•'s s = < * • º :689 ; ; , , , - - - - 71o * ... . . Highest station, 26:137 ........ 639. . . . . . . . . 559 ... Here we have, d r 5°, difference detached thermometer, - And.......... f = 63°, mean of attached.thermometer. . . . Log. 29.862 = . 1-475.119, . - Log. 26-137 = 1417256 * Difference of Logs. = 0.057863 = l. Then, by the first formula, f — 32° = 31°, and 1 + (31 × .00245) = 1.07595 10000 l = 10000 × 057863 - 578-63 •468 d = 468 × 5 . . . . ~ 2:34 * 576.29 Multiply by 1.07595 - 620 fathoms, the altitude sought; the decimals being rejected as unimportant, Ramsden’s engraved table gives the height = 3730 feet, or 6213 fathoms. This table is on a slip of paper, a foot long and about 3+ inches wide; the logarithmic differences, from 25 to 31 inches, are given to 500ths of an inch, and the corrections for the thermometer at both stations found by inspection. . It may be observed, that in determining altitudes by the barometer, it is best to make the observations at the upper and lower stations at one and the same time, as nearly as can be ; but great care must be taken that the two barometers, and also the thermometers, are alike; that is, they should precisely agree when together in all states of the air. It is also neces- sary that the specific gravity of the mercury be well ascer- tained, because it is not equally pure in all barometers; which is the principal reason why different results have been so frequently obtained, from observations made with different barometers at the same stations. Other circumstances, not generally known, may contribute to such disagreement; thus, Mr. Ramsden proved, by experiment, that the quicksilver in barometer tubes, made of different sorts of glass, will be sus- pended at different heights. * In the following Table, for measuring the altitude of any mountain, the first column expresses its height in feet or miles; the second, the height of the quicksilver; and the third, the descent of the quicksilver in the barometer; and this at a mean density of the air. Feet, High. Barom. Descent. i Feet. High. Barom. | Descent. | ^ ! 0 29-500 i 100 29:400 “100 : 2600 27.028 2.472 200 29-301 •199 $ 2700 26.933 2,562 300 29-203 297 : 2800 26'848 2’652 400 29' 105 '395 ; 2900 26°758 2.742 ºf 500 29.007 '493 : 3000 || 26.668 2.832 - $ - 600 28'910 •590 & 3100 || 26.578 2.922 ... I 700 28-812 -688 & 2200 . . 26489 3'011 800 28-716 '784 R 3300 26:400 3-100 900 28°619 •881 § 3400 26-311 3°189 1000 28'523 •977 : 3500 26.222 3.278" - * ... • 1100 28°428 1.072 $ 3600 26- 136 - || 3°364 1200 28-332 1-168 ; 3700 26-049 3°451 1300 28°237 1.262 : 3800 25.961 3539 1400 28°143 1.357. § 3900 25-874 3-626 1500 28°048 1-452 & 4000 25-786 3-714 º - | 1600 27.954 || 1:546 : 4100 25.699 || 3:801 tº º 37.8% 1°640 . i 4200 . . 3:63 '3°887 H. ...; ... ; ;| ≤ | }; & e & - 4. Pºº , 2000 27.579 1921 ; 4500 25-355 4°145 ^ - * - " . . . --- * 2100 27.487 || 2:013 : 4600 || 25-270 || 4:230 2200 27°394 2-106 : 4700 25, 185 . . 4.315 2300 27°302 2198 : 4800 || 25101 4-399 2400 27:210 & 2.290 : 4900 || 25.917 4°483 2500 | 27:119 "1, 2,381 $ 5000 24.933 4:567 . . B. A. R. B A. R. DICTIONARY or MECHANICAL scIENCE. 93 The Table continued, in Miles. Miles. | High. Barom. || Descent. i Miles. High. Barom. || Descent. 0° 29°50 .- $ - . 0°25 28-21 1.29 $ 3.25 | 16:57 12-93 0°50 26'98 2.52 $ 3.50 | 1585 13-65. 0-75 25.80 || 370 : 375 I5' 16. 14:34 1° 24.70, 4.80 : 4. 14°50 15:00 1.25 || 23°62 5.88 ; 425 | 1887 | 1663 1°50 22.60 | 6.90 : 450 13°27. 16:23 1.75 21-62 7.88 & 4.75 12-70 16:80 2. 20'68 8.82 : 5. 12° 15 17:35 Q - 2-25 1978 . 9-72 : 525 11-62 17-88 2°50 1893 10:57 : 5.50 11-12 18'38 2.75 | 18-11 11:39 : 5.75 10°64. 18°86 3. 17:32 12:18 : 6. 10:18 T9:32 Another sort of barometer shews the ascent and descent of the mercury at the bottom, as A B C (annexed figure) a recurve tube, close at the top, where the bucket C is, and open at the end A. The length of C B is 32 or 33 inches, and of A B 6 or 7. The bucket C should contain about as much as the end A B ; and the bucket and end C B must be quite filled with mer- cury, as far as B, a little beyond the turn. The wider the bucket C is, the better. The scale set to the end A B must be graduated downwards; for the mercury falls in this, when it rises in the other sort. This being placed against a wall, will shew the height of the mercury, as in the common ones; and this way is more commodious, as it saves the labour of clambering up upon chairs to see it, as one must do, in the common sort, to see the index exactly. A barometer may also be made of water, (as in the lower figure,) which is a water- barometer. A B is a glass tube open at both ends, and cemented close in the mouth of the bottle E F, and reaching very near the bottom ; then, warming the bottle at the fire, part of the air will fly out; then the end A is put into a vessel of water mixed with co- chineal, which will go through the pipe into the bottle as it grows cold. Then it is set upright; and the water may be made to stand at any point C, by sucking or blowing at A. And, if this barometer be kept to the same degree of heat, by putting it in a vessel of sand, it will be very correct for taking small altitudes; for a little alteration in the weight of the atmosphere will make the water at C rise or fall in the tube very sen- sibly; but if it be suffered to grow warmer, the water will rise too high in the tube, and spoil the use of it; so that it must be kept to the same temperature. If a barometer was to be made of water put into an exhausted tube, after the manner of quicksilver, it would require a tube 36 feet long or more; which could hardly find room within doors; but then it would go 14 times more exact than quicksilver; because, for every inch the quicksilver rises, the water would rise 14, from whence every minute change in the atmosphere would be discernible. And the water-barometer, above described, will shew the variation of the air's gravity as minutely as the other, if the bottle be large, to hold a great quantity of air. . The Diagonal BAROMETER acts on the same principle as the common barometer above described, except that the upper end of the tube is bent at about an angle of 45° from the verti- cal, whereby the scale of variations is iºreased in about the ratio of 3 to 2; or more accurately, in theºfatio of the diagonal É É# - -Elº- of a square to the length of its side. If the upper end be . . bent in a greater angle, the scale of variation will be so much the more increased; but in practice, it is not found convenient to have the angle much exceeding 45°. - The Horizontal BAROMETER, consists of a tube bent at right angles, having a pretty wide cylindrical part at the upper end of the vertical leg, which is hermetically sealed, the horizontal leg being open, where, however, the mercury cannot run out, being opposed by the pressure of the atmosphere, the varia- tions of which are indicated by a scale attached to that branch of the instrument. • The Marine BAROMETER of Dr. Hooke, is intended to be used on Shipboard, being contrived so as not to be affected or injured by the motion of the vessel. It consists of a double thermometer, or two tubes half filled with spirits of wine; the one sealed at both ends, with a quantity of air included ; the other sealed at one end only. The former of these is affected only by the temperature of the air; but the other, both by the external temperature, and by the variable pressure of the atmosphere. Hence, considering the spirit thermometer as a standard, the excess of the rise or fall of the other, beyond the former, will shew the increase or decrease of the pressure of the atmosphere. The marine barometer is a very useful instru- ment for indicating any change in the state of the weather. The Pendant BAROMETER is rather pretty than useful, and consists of a conical tube placed vertically, its upper and Smaller extreme is hermetically sealed, and its larger and lower end open; it has no vessel or cistern, its conical figure supplying that defect; for when filled like the rest, there will be as much mercury sustained as is equivalent to the weight of the atmosphere ; and as that varies, the same mercury takes up a jerent part of the tube, and so becomes of a different weight. - The Portable BAROMETER is so constructed, that it may be carried from one place to another without damage or derange- ment. . The end of the tube is tied up in a leathern bag, not quite full of mercury, which being pressed by the air, forces itself into the tube, and keeps suspended at its proper height. This bag is usually enclosed in a box, through the bottom of which passes a screw, by means of which the mercury may be forced to the upper end of the tube, and prevented from break- ing it by dashing against the top, an accident very likely to happen without this precaution. - The Reduced BAROMETER is only three inches long, and serves the purpose of a manometer, in shewing the dilations of the air in the receiver of an air-pump, for which purpose it is now commonly employed. The Wheel BARometer, as here re- S ſºr presented, was invented by Dr. Hooke, i ſ A- about the year 1668, and is meant to O render the alterations in the air more sensible. Here the barometer tube has . Tſº- a large ball, A B, at top, and is bent up at the lower or open end, where an iron ball, G, floats on the surface of the mercury in the tube, to which is con- nected another ball, H, by a cord hang- t ing freely over a pulley, turning an f index, KL, about its centre. In this instrument the variations of the mer- & cury take place in the lower part of T. the tube; for the height of the mercury - | being always the difference between Lºſ its upper and lower surface, and as in D ſ this instrument, in consequence of the Sºlºš great diameter of the ball, the mercury can rise but very little in the upper part, it follows that the most obvious variation must take place in the lower branch. Now, when the quicksilver rises in the part FG, it raises the ball G, and the other ball H descends and turns the pulley, with an index round a graduated circle, from N towards M and P, and the contrary way when the mercury and ball sink in the bent part of the tube. Hence the scale is easily enlarged ten or twelve-fold, being increased in proportion to the axis of the pulley, to the length of the index K.L. But.. Ø CD Ç 2 B 94 B A R. B A R. DICTIONARY of MECHANICAL scIENCE. \, then it must be observed, that the friction of the pulley and axis greatly obstructs the free motion of the quicksilver. This imperfection in wheel barometers has been in a great measure obviated by introducing two pulleys, moving on friction wheels. Various other barometers might here be enumerated, as constructed by Descartes, Huygens, De la Hire, Boyle, Orme, Caswell, Rowning, &c. many of them, however, now out of use, are purposely omitted. - Phenomena of the BAROMETER.—The phenomena of the baro- meter, considered as a weather-glass, have been very differ- ently stated and explained by various writers; and they are so precarious, that it is extremely difficult to form any fixed and general rules concerning them. Although the barometer never fails to indicate a storm, or any great change of weather, for some hours before it occurs; yet its variations aſſord no indications that are absolutely certain, with respect to those less consi- derable changes, to which the weather is subject in our variable climate. With certain restrictions they afford some ground for probable conjecture; and these restrictions are to be deter- mined merely by the sagacity of long-continued observation and experience. Strictly speaking, the height of the mercury in the barometer has no immediate and necessary connexion either with rain or fair weather. That its variable height is the immediate consequence of the variable pressure of the atmosphere, is a fact that admits of no doubt; but the causes of this variable pressure have not yet been fully and satis- factorily ascertained ; and how far the state of the wea- ther, in all its minute and sudden changes, depends upon it, is a question that is still to be determined. The mercury is commonly highest in winter and lowest in summer; it is least variable at the solstices, and most variable at the equinoxes. The principal observations that have been made on the varia- tions of this instrument, are summed up in the following par- ticulars:— 1. The more considerable elevations and depressions of the mercury in the barometer happen at a very short interval of time, in places very remote from each other. This corre- spondence was observed by Mr. Derham, in 1699, between the heights of the mercury at Upminster in Essex, and Townly in Lancashire; and afterwards by M. Maraldi, between the variations at Paris and Genoa, at the distance of nearly four degrees of latitude, who adds, during these variations, different winds prevailed at these places. But Mr. Kirwan observes, that where there is a considerable difference of longitude, the like agreement is not found. - 2. The deviations of the mercury from its mean annual altitude are far more frequent and extensive in the neighbour- hood of the poles than in that of the equator. At Petersburgh, in 1725, the mercury once stood at the amazing height of 31°59 inches, if we may credit Mr. Consett; and yet it has been so low as 28:14 inches. In the northern parts of France, the variations are greater than in the southern : at Naples, they scarcely exceed one inch. In Peru, under the equator, and at the level of the sea, they amount only to two or three tenths of an inch; but in other parts, within a few degrees of the line, on the approach of the rainy season, or of hurricanes, the barometer falls an inch or more. 3. The variations without the tropics, are greater and more frequent in the winter, than in the summer months. 4. The variations are considerably smaller in very elevat- ed situations than on the level of the sea. Thus M. Bouguer observed, that on the coast of Peru the variations extended to + of an inch; at Quito, elevated 9374 feet above the sea, they comprehend only 0.087ths of an inch. Saussure made similar observations in Savoy, as did M. Lambert in Switzerland. 5. The mean height of the barometer on the level of the sea, in most parts of the globe hitherto examined, is about 30 inches: M. Bouguer, under the line, observed it at 29.908 inches; but as his barometer was not purged of air by fire, it stood lower than it should have done. Sir G. Shuckburgh, on a mean of several observations on the coasts of Italy and England, found it at 30'04 inches, when the temperature of the mercury was 55°, and that of the air 62°. The mean height of the barometer in London, upon an average of two observations in every day of the year, kept at the house of the Royal Society, for many years past, is 29.88; the mean temperature or height of the thermometer, according to the same, being 58°. The greatest height observed by Sir G. Shuckburgh, Dec. 26, 1778, in Lon- dom, was 30-948 inches, the thermometer being at 479; and, reduced to the heat of 50°, it was 30'957; and this, he says, is the greatest height which, as far as he has been able to collect, it has ever been known to stand at in any country, where observations have been made and recorded, since the first invention of this instrument. In the proximity of the poles, says Mr. Kirwan, the annual mean heights of the barometer differ much more from the standard than in the more southern parts of our hemisphere. In estimating the connexion of the variation of the barometer with the weather, particular rules have been given by different philosophers; our limits, however, will only allow of stating those of Dr. Halley and Mr. Patrick, which are as follow :— Dr. Halley's Rules for judging" of the Weather.—1. In calm weather, when the air is inclined to rain, the mercury is com- monly low. - 2. In serene, good, and settled weather, the mercury is generally high. 3. Upon very great winds, though they be not accompanied with rain, the mercury sinks lowest of all, according to the point of the compass the wind blows from. 4. The greatest heights of the mercury are found upon easterly or north-easterly winds, other circumstances alike. h 5. In calm frosty weather, the mercury commonly stands igh. 6. After very great storms of wind, when the mercury has been very low, it generally rises again very fast. 7. The more northerly places have greater afterations of the barometer than the more southerly, near the equator. 8. Within the tropics, and near them, there is little or no variation of the barometer, in all weathers. For instance, at St. Helena it is little or nothing, at Jamaica #ths of an inch, and at Naples the variation hardly ever exceeds an inch ; whereas in England it amounts to 2% inches, and at Petersburgh to 33 nearly. - - Dr. Beal, who followed the opinion of M. Pascal, observes, that, carteris paribus, the mercury is higher in cold weather than in warm ; and in the morning and evening usually higher that at mid-day: that in settled and fair weather the mercury is higher than either a little before or after, or in the rain ; and that it commonly descends lower after rain than it was before it. And he ascribes these effects to the vapours with which the air is charged in the former case, and which are dispersed by the falling rain in the latter. If it chance to rise higher after rain, it is usually followed by a settled serenity. And that there are often great changes in the air, without any perceptible altera- tion in the barometer. Mr. Patrick's Rules for judging of the Weather.—These are esteemed the best of any general rules hitherto made: 1. The rising of the mercury presages, in general, fair wea- ther; and its falling, foul weather, as rain, Snow, high winds, and storms. - 2. In very hot weather, the falling of the mercury indicates thunder. - - 3. In winter, the rising presages frost; and in frosty weather, if the mercury falls three or four divisions, there will certainly follow a thaw. But in a continued frost, if the mercury rises, it will certainly snow. 4. When foul weather happens soon after the falling of the mercury, expect but little of it; and on the contrary, expect but little fair weather when it proves fair shortly after the mercury has risen. • . 5. In foul weather, when the mercury rises much and high, and so continues for two or three days before the foul weather is quite over, then expect a continuance of fair weather to follow. - - - 6. In fair weather, when the mercury falls much and low, and thus continues for two or three days before the rain comes, then expect a great deal of wet, and probably high, winds. 7. The unsettled motion of the mercury denotes uncertain and changeable weather. 8. You are not so strictly to observe the words engraven on the plates, as the mg ºury's rising and falling; though in gene- ral it will agree with them. For if it stands at much rain, and B A R. B A S DICTIONARY OF MECHANICAL SCIENCE. 95 then rises up to changeable, it presages fair weather; though not to continue so long as if the mercury had risen higher. And so, on the contrary, if the mercury stood at fair, and falls to changeable, it presages foul weather; though not so much of it as if it had sunk lower. Upon these rules of Mr. Patrick the following remarks are made by Mr. Rowning : That it is not so much the absolute height of the mercury in the tube that indicates the weather, as its motion up and down: wherefore, to pass a right judg- ment of what weather is to be expected, we ought to know whether the mercury is actually rising or falling; to which end the following rules are of use: - - I. If the surface of the mercury is convex, standing higher in the middle of the tube than at the sides, it is a sign that the mercury is then rising. 2. But if the surface be concave, or hollow in the middle, it is then sinking. And, 3. If it be plain, or rather a very little convex, the mercury is stationary: for mercury being put into a glass tube, espe- cially a small one, naturally has its surface a little convex, because the particles of mercury attract one another more forcibly than they are attracted by glass. Farther, 4. If the glass be small, shake the tube; then if the air be i grown heavier, the mercury will rise about half a tenth of an inch higher than it stood before; but if it be grown lighter, it will sink as much. And, it may be added, in the wheel or circular barometer, tap the instruuent gently with the finger, and the index will visibly start forwards or backwards, accord- ing to the tendency to rise or fall at that time. This proceeds from the mercury’s sticking to the sides of the tube, which prevents the free motion of it till it be disengaged by the shock: and therefore, when an observation is to be made with such a tube, it ought to be first shaken ; for sometimes the mercury will not vary of its own accord, till the weather is present which it ought to have indicated. - BAROSCOPE, an instrument for shewing the weight of the atmosphere, frequently confounded with barometer: they are not, however, precisely the same ; the one being intended only to shew that the air has weight, whereas the other measures that weight, and determines its true quantity. BARREL, an English vessel or cask, which contains 36 gal- lons beer measure, and 32 gallons ale measure. The barrel of beer, vinegar, or liquor preparing for vinegar, ought to contain 34 gallons, according to the standard of the ale quart. Barrel is also used as a measure in various commodities; thus, Barrel of Essex butter is ...... 106 lb. Barrel of Suffolk butter, ...... 256 lb. f Barrel & of herrings holds..... ... 32 gallons wine measure. 1000 herrings. 42 gallons. 256 lb. & and contains about.... Barrel of salmon holds ... . . . . . Barrel of soap is ........... © gº º BARREL, in Machinery, is also applied to any thing hollow and cylindrical, as the barrel of a pump, of a gun, of a watch, &c. BARROW, ISAAC, a very eminent mathematician and divine of the 17th century, was born at London in October, 1630, and died in May, 1677, in the 47th year of his age. He was the preceptor and friend of the celebrated Newton, by whom only, says Dr. Pemberton, he was surpassed in genius and invention. Barrow was the author of a great number of works both on theology and mathematics:- BARRY, in Heraldry, is when an escutcheon is divided bar- wise, or from side to side, into any number of compartments, with tinctures interchangeably disposed. BARTER, is the exchanging of one commodity for another, and forms a rule in the commercial part of arithmetic; is nothing more than simple proportion, or the rule of three, and serves to teach us not to sustain loss in the exchange of goods. Rule 1–Find the value of that commodity whose quantity is given; then find what quantity of the other, at the rate pro- posed, you may have for the same money.—2. When one has goods at a certain price, ready money, but in bartering advances it to something more, find what the other ought to rate his goods at, in proportion to that advances and then proceed as before. - - º Example 1. What quantity of chocolate, at 4s. per Ib. | must be delivered in barter for 2 cwt. of tea, at 9s. per lb. ? Erdimple 2. A and B barter; A hath 20 cwt. of prunes, at 4d. per lb. ready money, but in barter will have 5d. per lb. and Cuyt. Bhath hops worth 32s. per cwt. 2 ready money; what ought B 112 to rate his hops at in barter, --- and what quantity must be given for the 20 cwt. of prunes? . . 9 . . . . . * * * - * * * lb. d. d. J. 4)2016 the value of the tea. 1 cwt, it 112 As 4: 5 : : 32 - -- 20 5 504 lb. of chocolate must s. -mº * be delivered in barter for 2 cwt. 40 2240 4)160 of tea at 9s. per lb. 12 5 - - -*** c. q. lb. 40s. 48|0)11200(23 1948 Answer. 96 160 144 16 = 1 qr, 9% lb. ' -*º BAS ALTES, in Natural History, a heavy hard stone, chiefly black or greenish, consisting of prismatic crystals, the number of whose sides is uncertain. This mineral always stands upright in columns, and the British dominions present the noblest specimens in the known world of columnar basalt; amongst which, the Giant's Causeway, in Ireland, stands Giant's Causeway. --/ } |) jºrintimº conspicuous. It consists of three piers of basalt columns, which extend some hundred feet into the sea, surrounded by precipitous rocks, from 200 to 400 feet high, in which there are several striking assemblages of columns, some vertical, some bent or inclined, and some horizontal, and as it were driven into the rock. Bengore, which bounds the Causeway on the east, consists of alternate ranges of tabular and massive, with columnar basalt. But among the various and grand objects on this coast, Pleskin is perhaps the most striking: it presents several colonnades of great height and regularity, separated from each other by tabular basalt; and at Fairhead, the north- east cape of Ireland, and forming the east side of Ballycastle Bay, there is a range of columns of from ten to twenty feet diameter, and between 200 and 300 feet high, supported upon a steep declivity, and offering to the mariner at sea the spec- tacle of a terrace, which towers nearly 600 feet above the waves that roll beneath. Among the Hebrides of Scotland the isles of Ulva, Gometra and Staffa, and Mull, exhibit massive and columnar basaltes, which abounds in black oxide of iron, and bears a strong resemblance to lava, yet the lava of Mount Etna, in the year 1649, ran into the sea for two leagues and a **** * B A T B A. T. DICTIONARY of MECHANICAL scIENCE. half without having the least appearance of being converted into basaltes. - n Chemically analyzed Basaltes and Lava give the following results. Basaltes 100 parts, contain Lava 100 parts, contain Siliceous earth ...... parts 50|Siliceous earth "......parts 49 Argillaceous.............. 15|Argillaceous...... , . . . . . . . 85 Calcareous . . . . . . . . . . . . . . . 8| Calcareous............ . . . 4. Magnesia. . . . . . . . . & Q we e - E & 2|Iron . . . . . . . . . . . . . . . . . . . . . 12 Iron... . . . . . . . . . . . . . . . . . . . 25 sº-º-º- -º- 100 100 Wºmº-º The basaltes of Staffa contains 50 parts of flint; the lava of Catanea Mount Etna, 51 parts; the whinstone of Salisbury Craig near Edinburgh, 46 parts of flint; that of the Calton Hill Edinburgh, 50; and the lava of Sta. Veneve, Etna, 503 parts flint in every 100 parts. These analogies are very singular in these marbles; which have been considered by some as crystallizations from water. BASE of a FIGURE, in Geometry, denotes the lowest part | of its perimeter; in which sense the base stands opposed to the vertex, which denotes the highest part. BAse of a right-angled triangle, is properly the hypothenuse, though it is generally used to denote one of the sides about the right angle, the other side being called the perpendicular; this, however, depends totally upon the position of the figure, as, properly speaking, that side which is lowest, or on which the figure stands, is the base; and for this reason that side on which a solid body stands is called the base of a solid. BASE of a Conic Section, is a right line in the parabola and hyperbola, formed by the common intersection of the cutting plain and the base of the come. BASE, in Surveying, is a line measured with the greatest possible exactness, on which a series of triangles are con- ..", in order to determine the position of objects and places. - - BASKERVILLE, John, an eminent artist in letter founding and printing, was born at Woverley in Worcestershire, in 1706, and after bringing the printing of books to its greatest perfection, in Birmingham, he died, without issue, in 1776. BASSOON, a musical instrument of the wind sort, blown with a reed, furnished with eleven holes, and used as a bass in a concert of hautboys, flutes, &c. To render this instrument more portable, it is divided into two parts, whence it is also called a baggot. Its diameter at bottom is nine inches, and its holes are stopped like those of a flute. BASTION, in Fortification, a large mass of earth, faced usually with sods, sometimes with brick, standing out from a rampart, whereof it is a principal part. The bastion consists of the face, flank, curtain, and gorge, as marked in the figure. BATH, a receptacle of water in which to plunge, wash, or bathe the body; and the water may be either hot or cold, natural or artificial, of fresh water or of salt. In this country we have hot natural baths at Bath, Bristol, Buxton, and Matt lock, which are all beneficial in diseases of the head, palsies, cutaneous diseases, scurvy, obstructions, &c. The Russians cure all diseases by hot baths, and now, in Britain, vapour baths, as Captain Jekyll's, (see the next figure,) are becoming very common. The Captain's bath is also a portable machine, and he carries it about with him, we believe, whenever he removes from his residence in Somersetshire to London. 2 º s H S BATHING, immersing the body in hot or cold water, or in Steam, made as it were a part of the existence of the ancients. But when the vapour is passed through a cloud of burning perfumes, the bather is extended freely on a couch, and a servant kneads the whole body without causing the slightest pain, and then rubs the skin with a fine glove, till it becomes soft and smooth like silk; it is then indeed that one experiences a universal comfort, and health resulting from cleanliness: the bath adds both to the happiness and longevity of its votaries. BATTALION, a small body of infantry, aranged in form of battle, and ready to engage an enemy. It consists of from 500 to 1200 men, armed with firelocks, swords, and bayonets, divided into 13 companies, one of which is the grenadier com" pany. Some regiments consist of one battalion, others of 2, 3, 4, or 6 battalions. BATTERING RAM, or ARIes, an ancient military engine, employed for destroying the walls of fortified places, of which there were three different sorts; the first rude and plain, the others artificial and compound. The first seems to have been nothing more than a great beam, having a heavy head of iron, which the soldiers bore in their arms, and with one end of it assailed the walls by main strength: this of course was worked at a great expense...of labour, and without producing any remarkable effect. The second sort, as described by Josephus, consisted of a very heavy beam, headed with iron as above, and suspended in the middle from another strong beam supported > S| on two posts, which being erected under the walls of the place, was swung backwards and forwards, by the soldiers, till, by the repeated shocºthus given, the wall was totally demolished: this machine was sºmetimes covered by a Screen, in order to R A T B A T DICTIONARY OF MECHANICAL SCIENCE. **, *.x. §7. protect the soldiers from the assäults of the enemy. above figure represents the second kind of battering-ram suspended ; 2, the ram ; 3, the form of its head, fastened to the enormous beam, by three or four bands of iron, four feet in breadth. At the extremity of each of these bands, (4) was a chain (5) of the same metal, one end of which was fastened to a hook, (6) and at the other extremity of each of these chains was a cable firmly bound to the last link. These cables ran the whole length of the beam, to the end of the ram, (7) where they were all bound together as fast as possible with small ropes. To the end of these cables another was fixed, com- posed of several strong cords, plaited together, to a certain length, and then running single (8.) At each of these several men were placed to balance and work the machine. 10, the chain or cable by which it hung to the cross beam (11) fixed on the top of the frame : 12, the base of the machine. The unsuspended ram differed from this, only in the manner of working it; for instead of being slung by a chain or cable, it moved on Small wheels, on another large beam. ºr Plutarch informs us, that Marc Antony, in the Parthian war, used a ram of 80 feet long; and Vitruvius says that they were sometimes 106, and even 120 feet long, and weighed 100,000 pounds; at least this is said to have been the weight of that employed by the emperor Vespasian. by their own weight, and by the action of the men who impelled them, excited a force which in some cases exceeded the utmost effect of our battering cannon. Desaguliers (Lectures, vol. i. p. 65) has demonstrated, that the momentum of a battering ram, 28 inches in diameter, 180 feet long, with a head of cast iron of one ton and a half, the whole ram weighing, with its iron hoops, 41,112 pounds, and moved by the united strength of 1000 men, would only be equal to that of a ball of 36 pounds weight shot point blank from a cannon. And Atwood, com- paring the effect of the battering ram, having its metal extremity equal to a twenty-four pounder, with a cannon ball of 24 pounds weight, observes, that in order to their producing the same effect in penetrating a wall or making a breach in it, the weight of the ram must exceed that of the cannon ball in the proportion of the square of 1700, the velocity of the ball, to the square of the velocity with which the battering ram could be made to impinge against the wall, expressed in feet. Esti- mating this at ten feet in a second, the proportion of the weights will be that of about 2,890,000 to 100, or 28,900 to 1; and therefore the weight of the battering ram must be 346 ton. In this case the ram and the cannon ball, moving with the velocities of 10 and 1700 feet in a second, would have the same effect in penetrating any obstacle; but as the weight of the ram was probably never so great as the above supposition states it to have been, the force of a cannon ball to make a breach in walls must exceed that of the ancient aries; but the momentum of this, or the impetus by which it communicated a shock to the whole building, was far greater than the utmost force of cannon balls; for if the weight of the battering ram were no more than 170 times greater than that of a cannon ball, each moving with its respective velocity, the momenta or forces of both would be equal; but as the weight of this ancient machine was certainly much greater than 170 times that of our heaviest cannon balls, their momentum or impetus to shake or overturn walls and demolish buildings, was much superior to that which is exerted by the modern artillery. And since the strength of fortifications will, in general, be proportioned to the means which are used for their demolition, the military walls of the moderns have been constructed with less attention to their solidity and massy weight, than the ancients thought to be a necessary defence against the aries; that sort of cohe- sive firmness of texture which resists the penetration of bodies, being now more necessary than in ancient times. The ram was frequently used in the fourteenth century. Sir Christopher Wren employed it in demolishing the walls of the old church of St. Paul, previously to his building the present structure; and found no machine so well adapted to this purpose. BATTERY, in the Military Art, a parapet, thrown up to cover or protect from the enemies' shot, the gunners, and men employed about the guns. . In this bank or parapet are cut holes or embrazures, through which the cºon are projected to be fired. - - * . The These battering rams, I i BATTERY, in Law, is beating another person unlawfully, for which the remedy is, as for assault, by action of trespass vi et armis, as the lawyers term it; wherein the jury will give adequate damages. BATTERY, in Electricity, is a combination of coated sur- faces of glass, commonly jars, so connected together that they may be charged at once, and discharged by a common con- ductor. Dr. Franklin constructed a battery consisting of éleven panes of large sash glass, coated on each side, and con- nected in such a manner, that the whole might be charged. together, and with the same labour as one single pane; and by bringing all the giving sides into contact with one wire, and all the receiving sides with another, he contrived to unite the force of all the plates, and to discharge them at once. Dr., Priestley describes a still more complete battery: this consists. of 64 jars, each 10 inches long, and 2% inches in diameter, all, coated within an inch and a half of the top, forming in the whole about 32 square feet of coated surface. A piece of very fine wire is twisted about the lower end of the wire of each jar, to touch the inside coating in several places; and it is put through a pretty large piece of cork, within the jar, to prevent. any part of it from touching the side, by which a spontaneous discharge might be made. Each wire is turned round so as to. make a loop at the upper end ; and through these loops passes a pretty thick brass rod with knobs, each rod serving for one row of the jars; and these rods are made to communicate together by a thick chain laid over them, or as many of them. as may be wanted. The jars stand in a box, the bottom of which is covered with a tin plate; and a bent wire touching the plate passes through the box, and appears on the outside. To this wire is fastened any conductor designed to communi- cate with the outside of the battery; and the discharge is made by bringing the brass knob to any of the knobs of the battery. When a very great force is required, the size or number of the jars may be increased; or two or more batteries may be used. The large and powerful battery of Dr. Van Marum, constructed for Tayler’s museum at Haarlem, consists' of a great number of jars coated as above, to the amount of about 130 square feet; and the effects of it are truly astonish- ing. The annexed figure represents a battery consisting of . "F sixteen jars, coat- ed with tinfoil, . and disposed in a proper box. The wires, which pro- ceed from the in- side of every four of those jars, are screwed, or fast- ened, to a com- mon horizontal wire E, which is knobbed at each extremity, and by means of the wires F, F, F, the inside coat- ing of 4, 8, or 12, or of all the sixteen jars, may be connected. The inside of the box which contains these jars is lined with tinfoil. On one side of this box there is a hole, through which a strong wire or hook passes, which communicates with the lining of the box, and of course with the outside coatings of the jar. To this hook a wire is occasionally fastened, which connects it with one branch of the discharging rod, B B C.A. By means of the battery, electricity is capable of producing the most powerful effects. Experiments.--A very slender wire, as a, being made part of the circuit, will, by the discharge of the battery, instantly become red-hot. It sometimes melts into small globules of different sizes. If between two slips of window-glass some gold-leaf be placed, and the slips of glass be pressed firmly together, and the shock from a battery be sent through them, the gold-leaf will be forced into the pores of the glass. If the gold-leaf be put between cards, and a strong charge be passed through them, it will be completely fused. Gunpowder may also be fired by the electrical battery. . ‘ 1 • BATTLE, a general engagement between two armies, in a country sufficiently open for them to encounter, and at the "U-ſ’ | same time, in front. See WAR. 2 C 98 B E E B E E DICTIONARY of MECHANICAL SCIENCE. BAYER, John, a German astronomer of the 17th century, who published, in 1603, an excellent work entitled “Urano- metria,” being a celestial atlas, or charts of all the constella- tions: he first distinguished the stars by the letters of the Greek alphabet, and according to the order of the magnitude of the stars in each constellation. This work was republished by the author in 1627, under a new title, viz. “Coelum stellatum || Christianum :” here he rejected the old figures of the constel- lations, and inserted others taken from the scriptures: but this innovation was not relished; and accordingly we find, that in the later editions of 1654 and 1661, the ancient figures and names were restored again. BEAMS, in Naval Architecture, strong thick pieces of tim- ber, stretching across the ship from side to side, to support the decks, and retain the sides at their proper distance, with which they are firmly connected by means of strong knees. They are sustained at each end by thick planks in the ship's side called clamps, upon which they rest. Midship BEAM, the longest beam in a ship, being lodged in the midship frame, or between the widest frame of timbers. At about two-thirds of the height from the keel to the lower deck, are laid a range of beams to fortify the hold and support a platform called the orlop, which contains the cables and stores of the ship. There are usually twenty-four beams on the lower deck of a ship of seventy-four guns, and to the other decks, additional ones in proportion as the ship lengthens above. It is necessary that the beams should have a greater height in the middle than at the two ends, to carry the water more readily off from the decks, and to diminish the recoil of the guns, which will thereby more easily return to their places. Orlop Bea Ms, support the orlop deck, but are chiefly intended to fortify the hold. On the BEAM, implies any distance from a ship on a line with the beams, or at right angles with the keel. Before the BEAM, is an arch of the horizon, comprehended between a line that crosses her length at right angles, and some object at a distance before it; or between the line of the beam and that point of the compass which she stems. On the Weather BEAM, on the weather side of the ship. BeAM ends, a ship is said to be on her beam ends, when she inclines very much on one side, so that her beams approach to a vertical position; hence also a person lying down is said to be on his beam ends. - BEAM of a Balance, the horizontal piece of iron from the ends of which the scales are suspended. BeAM Compass. See ComPAss. BEAR, Great and Little, in Astronomy, the same as Ursa Major and Ursa Minor, which see. BEARD of a Comet, the rays which it emits in the direction in which it moves, as distinguished from the tail, or the rays emitted or left behind it as it moves along, being always in a direction from the sun. See CoMet. BEARING, in Geography and Navigation, the position of one place with regard to another, as estimated by the points of the compass. Thus a place is said to bear north-east, or north-north-east, &c. meaning, that it lies from your present situation in those directions. BEER-DRAwi NG MACHINEs are contrivances by means of which the beer is drawn from several casks at once, from cocks standing in a frame, in the bar of a tavern, or any convenient place above a cellar. These machines are merely an assem- blage of small pumps, either sucking or forcing, whose pipes of communication are attached to the lower parts of the respec- tive casks from which the liquor is drawn. The motion is given to the piston sometimes by levers, at others by cranks; but most frequently by means of a hammer-formed lever mov- ing in a vertical plane. BEES. There is no kind of stock in which a purchaser is so easily deceived as that of a hive of bees. The following are the best criterions by which to judge of its value. If a hive be purchased in the spring, it should never weigh less than fifteen pounds; if in the autumn, never less than thirty ; and if it be a stock hive, its weight should be forty pounds, for all old hives contain a certain portion of the bee bread. Great care should be taken in weighing a hive, lest the comb should be shaken, and so loosened. The middle of the day is the best time to . choose, a hive, and the following points should be strictly attended to: - te sº 1. The more numerous the bees which enter the hive with yellow balls or pellicles, the better the hive is. 2. The drones should likewise be numerous. 3. The activity of the bees; for if they saunter about, and then re-enter the hive without taking wing, it is a bad symptom. 4. The courage they display in repelling the strange bees. 5. The number of bees who remain at the entrance of the hive fanning with their wings—the greater the internal popula: lation: this circumstance is a strong proof of the excellence of a hive. 6. A swarm should always be put into a new hive. tº 7. The examination of a stock-hive may be pursued with safety, however courageous the bees may appear, by smoking a little tobacco near the hive. But as it may happen that the unskilful apiarian may be stung, the sting should be imme- diately extracted, and a little goulard water, or laudanum, or sweet oil, instantly applied to it. The mid-day is a better time for the examination of a hive than the evening; and the editor of this work performed this very operation on the day he penned these observations. Internal Appearances of a good Hive.—1. The hive should be crowded with bees. - 2. The combs should be yellow ; if of a blackish tint, reject it. 3. The side combs should be filled with honey; this may be known by their being sealed up. 4. A number of queen-bee cells (which resemble inverted cupping cups) is a sign that it is a very old hive; it should therefore be rejected. 5. If an unpleasant odour issue from the hive, it is unhealthy. The smell of a healthy hive resembles that of heated wax, par- taking at the same time of the fragrance of honey. Two or three bees should, however, be sacrificed, to ascertain the state of the bees: if the substance in the stomach be of a yellowish colour, and smelling somewhat like honey, the bees are in good health; if, on the contrary, it be blackish, with a fetid smell, the dysentery reigns among them. g 6. If dark liquid spots are seen on the board of the hive, it is a bad sign; the dysentery is making ravages within; and if a great number of small particles of wax are also observed, the hive is infested with moths. 7. If the wings of the bees are ragged and torn, the hive is old—have nothing to do with it. The hive should be carefully removed in the evening; the hole of entrance should be stop- ped up with clay, as well as every other crevice through which a bee could make its escape. Let them settle half an hour before the clay is removed. The hives should stand on sepa- rate pedestals a yard apart. Among the various plans proposed for the cultivation of bees, we shall notice in this place Milton's newly invented double-topped Straw Hive. Proceed to hive a swarm in the lower part of the hive in the usual way, as in the figure. The board at the top must be kept close, by secur- ing the openings by means of a thumb- screw, so that when first hived, the holes of both - boards shall not corre- spond, and by thus turning the upper board, it will prevent the bees from passing through, while hiving. At night, bring the hive into the bee-house, or where you intend it should stand ; in - about two days after, place on the glasses, as in the figure, (p. 99,) over their respective openings, and stop them round with mortar; after which, turn the board B to admit the bees to ascend for the purpose of working, cover the glasses with the small upper hive,C, and do not look at them for a few days. Indeed, nothing will then be necessary, but to ascertain when they are filled, which is known by the cell being sealed over, which you may expect in about twenty days after a swarm has been hived. - gº - When you wish to take the honey, and to remove all the glasses, turn the board to exclude the bees; then with a thin knife loosen them from the adapter; leave them thus for about an hour: then carry the glasses, inverted, a short distance B E. E. B E. E. DICTIONARY OF MECHANICAL SCIENCE. 99 from the hive into the shade; or raise the glasses with a small wedge, and those few bees which remain will rea- dily leave, and return to their original hive. This, if effected early in the season, will afford you the opportu- nity of immediately replacing the same, or another set of glasses, to be again filled. If you wish at any time to take only one or two of the glasses, with honey, do not turn the board, but loosen such glasses as you are desirous to remove, with a thin knife, set them on a divider, and replace others in their stead. The middle of a fine day is the best time to remove glasses. It will not be advisable to take any honey from the hive after the end of July, as the remaining part of the season might not prove favourable to the gathering enough for winter support; thereforeit - will be necessary, about this time, or early in August, to remove all the glasses and turn the board, to finally shut them up. It may be well to mention, that those glasses, only partly filled with combs, should be carefully set aside, to be placed on again the following April; if, however, you find the stock will require feeding, you have only to leave one or more of the glasses with honey for that purpose, which is by far the best mode. Thus much for the swarm, which we now leave till the follow- ing April—the time to again commence working the glasses, as hives are now full of combs and brood: should the season prove favourable, you will work the glasses twice or more, and you may calculate upon equal success every subsequent year; but the first season you cannot expect a swarm to fill the glasses more than once, which will produce you 8 lbs of the finest honey.—This method of management will not prevent the bees from swarming. - The honey thus obtained will be of the finest quality, pure, free from the young brood, of remarkably fine fragrange, clear, and very superior to any produced from common hives; it may also be taken at pleasure, without injury to the bees; especially, without being obliged to resort at any time to the painful process of smothering these industrious and valuable insects. The Double Cottage Straw Hive—This hive, for use, will answer many purposes in the keeping of bees, as you may work either a glass or a small straw hive on the top of it, which gives it an ad- vantage over the common hive, al- though the method of management is simple, and the price easy. Prepare this hive for a swarm by spreading mortar round the crown, to carry the adapter to support a glass or small straw hive, as you may work with either. Hive the swarm as usual, tak- ing care to secure the opening at the top; after removing it to its appointed place, let the swarm work for ten days; clear the opening at the top, and affix on either a glass or a small straw hive: the bees will then ascend to work. Stop the upper hive round with mortar to the adapter, and darken it with a common hive; in the course of from fifteen to twenty days examine it, and if full, take the honey thus:-pass a knife or wire between the adapter and small hive, to separate the combs; then remove the small hive of honey on a divider, (a tin or brass plate, twelve inches square,) it will then be immediately necessary to place a small hive on the adapter, or stop the opening till you wish to work another hive. Carry the small hive now on the divider a short distance away, or rather into a darkened room; invert it, and place over it a small empty hive of the same size; keep them steady, and, by tapping round the bottom hive, the bees, in a few minutes, will ascend to the hive above; carry them to within about two yards of their original stock, shake them out, and they will enter again as usual. A Superior Bor Hive—This box hive consists of three di- visions, as shewn in the figure, and issoingeniously construct- ed, that you may take the finest honey without destroying the bees; you may also work a glass hive on the top, and in- spect the whole of their curious and interesting labours with- out disturbing them. When you place a swarm in this hive, shut the slider of the adapter F, tie a small cord round to secure the parts, hive the swarm in the usual manner; at night bring it into your bee-house, or appointed place, open the entrance at T the bottom, and remove the cord; if you work a glass hive on the top, place it on the same evening, stop it round, draw back the slider to clear the grating, leave it a few minutes, and the bees will ascend for working. Then raise the two upper divisions, to enable you to remove the bottom division, and by the com- pression you oblige the bees to work in the glass hive, which should be darkened with its proper cover G, and left for a few days without being looked at: it will be necessary to replace the unemployed division at the bottom four or five days pre- vious to the removal of the glass of honey; in removing which, shut the slider, and leave it in this state for an hour; then follow those plain directions already laid down for the removal of glass and double-topped straw hives. If you wish to take more honey from this hive than the glass affords, examine the divisions early in September: if the three are full, viz. the two upper hives of honey, and the bottom of combs, and not otherwise, proceed to remove the fillets of the top division, and pass the brass divider between those parts, where it should remain for an hour; then raise the division with a wedge, and draw back the slider of the adapter to let the bees out, and when clear, which will be in a few minutes, remove this division, and place the adapter to the next divi. sion, and by withdrawing the divider it will fit close down: when you have taken out the combs of honey from this divi- sion, it should be replaced at the bottom; consequently, every year, or once in two years, you give them as it were a fresh division, as in the annexed figure, or part of a hive to re- build in, which keeps the bees constantly at work, and the combs in a good state of pre- servation. The Heragon Box Hive and Straw Hive, with slider and grat- ing, for working a large glass hive on the top, consists of a box, as represented in the annexed figure, having large glass windows, and supporting a glass hive on the top. When well supplied with bees, this hive affords the pleasing opportunity of viewing the progress of their labours, and exhibits a very interesting and beautiful appearance. To hive a swarm, shut the slider over the grating, and then proceed as before directed. When a glass hive is to be worked, follow the instructions already given with the supe- rior box hive. The hexagon hive is well calculated to work bees from other hives, particularly the common hive, especially when they are in a state of decay; it is effected merely by with. | | * | lº | - --- - 100 B E E B E. E. DICTIONARY OF MECHANICAL SCIENCE. drawing the slider clear of the grating, and placing the com- mon hive over it in the evening, taking care to stop the entrance of the former with clay. The bees will of course then en- ter at the bottom, and when they have worked the bottom hive nearly full, which you ascertain by means of the windows, carefully lift them up, and place under, them another hexagon hive; con- iſ: sequently, this colony con- ; sists of three hives, and it ºf will not be safe to remove the upper hive, unless the bees have worked combs - into the bottom hive, which, if effected at the end of the season, you may safely take the common bive, with its contents. The flat-topped straw hive, described by Mr. Wildman, is directed to be used in a similar manner, answering the purpose only to a certain extent, as it does not admit of windows, to enable you to know when the bees have finally worked down. The Common Hive, as here represented, is in such general use in this country, that it requires but little observation, except on some essential points, which, to benefit the cultivator, ought to be attended to. First, care should be taken to have the hive made of clean and good straw, and manufactured of a suitable thick- ness. Secondly, a hive should be chosen in proportion to the size of the swarm ; and when you have succeeded. → ... in obtaining a good hive, and placed a swarm in it, which should fill it to within a rim or two of the bottom, shelter it from cold winds and rain; for if once the wet penetrates a hive, it affects the combs, and the bees, getting a distaste for their home, will work very slowly, and often desert it altoge- ther. It is not material in what aspect the stock stands, pro- vided the sun shines on the hive once in the course of the day. Well-peopled hives kept dry, will thrive in any situation. One of those fatal incidents to which this hive is subject, occurs through covering it with a hackle or turf, by which you entice the mouse to make a nest on the top, and ultimately eat its way through the crown of the hive, and destroy both combs and bees. About August, the robbing commences by stranger bees and wasps, which is but little regarded : an important benefit will be derived by destroying the queen Wasp, seen about April, which is the mother of thousands; much, there- fore, is saved in the preservation of those hives which stand the winter. In September, your attention should be directed to weigh your stocks; none of those of less than from fifteen to twenty pounds in weight can safely be relied on to stand the winter. without feeding; and stop all hives down to the board with mortar. * Pasturage, or Bee-Flowers.-Bees are fond of those places where their favourite flowers are to be found; therefore bee- keepers should encourage the growth of such shrubs and flowers as are known to supply honey and wax in the greatest abundance; in most situations bees do not fly far for food, generally not more than half a mile; they may be observed to return with great precipitation to the hive when rain or a storm approaches. The following are the most favourable for pas- turage, and those which blossom early are the most desirable: Shrubs, &c.—All fruit trees, lime trees, furze, broom, heath, sallow or gray willow, rosemary, barberry tree, gooseberry, raspberry. Flowers.—Hyssop, mustard; turnips, cabbage, and white clo- ver, left for seed ; beans in bloom, mignonette, lemon thyme, garden and wild thyme, borage, winter savory. Mignonette, borage, and lemon thyme, are the principal, as they continue long in bloom, and afford the finest honey. Rosemary is also a great favourite, but seldom supplies much honey, unless the weather proves very hot and dry when it is in blossom, yet it is worth cultivating, especially in a southern | º aspect, being one of the principal aromatic plants from which the bees in §: neighbourhood of Narbonne collect their honey and it is esteemed the finest in Europe. Fields of beans, white clover, and buck-wheat, are of great benefit, Rivers or streams of water are also very beneficial, as bees make use of a great deal of water. - * Swarming, or the stock-hive casting part of its inhabitants for a fresh colony, depends on the increase of bees, and a queen being ready to lead them. Their breeding begins sooner or later, according to the forwardness of the spring, the fruit- fulness of the queen, and the strength of the hive. When bees carry in farina or pellets on their thighs, it denotes they have commenced breeding, which may be as early as February, and not finish till October; and when their numbers are much increased, they shew the indications of swarming, by their clus- tering in great quantities below the resting board. They never rise but on a fine day, and sometimes will settle, and for some cause return to the stock, probably for want of a queen being with them. Some hives will cast three times, but mostly only twice. The second cast you may expect within three or four days, and never later than ten days after the first. Should a stock overswarm itself, it will perish, unless strengthened; this may be ascertained by observing the quantity of bees after- wards seen to enter. It is necessary in the swarming season. from April to July, particularly in May and June, to observe the hives on a fine day; in general, the bees issue forth in new colonies, about noon—from nine to about three in the after- In OOI!. Hiving.—Bee-keepers should have spare hives prepared to hive the bees as soon as they have settled ; for, should the sun shine hot on the swarm, it may take another flight, and you may possibly lose it. The manner of hiving them must be regulated by the nature of the place on which they settle. The custom of preparing hives varies; a clean new hive only requires the loose straw to be rubbed off with a cloth; if any dressing be used, fennel dipped in boiled ale and sugar will best answer the purpose. Have ready a cloth whereon to place the hive, and a wedge to raise it: if the swarm should settle on a branch, shake the best part of it into the hive, place it on the cloth on the ground, and continue to disturb the swarm where it settled, and the hive being left underneath, they will all go in ; or cut the branch off, and gently place it in the hive. Should the bees settle on the ground, place the hive over them; and though bees are not apt to sting at this time, the hiving should be performed quietly. Avoid talking and breathing on them, and if you crush any of them they will resent it; therefore, to prevent accident, invariably put on gloves and a veil, which will give you confidence. All swarms are to be sheltered, and left near to where they settle till the evening; thence to be removed very gently to the appointed place. Uniting Swarms, and reinforcing Stocks.--It is essential, when you have weak swarms of bees, that you should strengthen them. The idea so prevalent, of the greatest number of hives. producing the most honey and wax, is erroneous; for great part of the bees are necessarily employed in rearing the young, and therefore the number of those who are occupied in col- lecting honey is not so great as has been imagined ; for every swarm, the least as well as the greatest, is provided with a queen, equal in fecundity to the queen of the larger stock, and as the brood she brings continually demands the labour and attendance of nearly half the bees, this circumstance renders the other moiety, from the smallness of their number, unable to accumulate a large quantity of honey in the short time it mostly abounds, and therefore honey cannot be obtained, in glass hives or otherwise; but from a strongly-peopled hive. The Method of Uniting:—Hive the swarms or casts in the usual way, and in the evening spread a cloth on the ground, near the hive to be reinforced ; bring the new swarm, and strike it down flat on the ground. The bees will then fall in a cluster; quickly place over them the stock to be reinforced; in ten minutes they will have united and become as one family, to be removed the same evening to its former situation. Another Method of Uniting:—Each cast or swarm to be hived separately ; in the evening, turn the crown of the hive into a pail, and set the other hive exactly over it; in the morn- ing, the bees from the bottom hive will have ascended. B E E B E E 101 f) ICTIONARY OF MECHANICAL SCIENCE, The system of uniting, so very important, is but little prac- tised, and has been overlooked by many cultivators; but we are thoroughly convinced, from experience, that it is absolutely necessary to have hives well peopled, and completely sheltered from wet, which are the principal and main objects to be attended to in the art of bee-keeping; and the advantages of uniting swarms will be found particularly beneficial in working the glasses with the newly-invented double-topped hives. Feeding.—With the aid of feeding, it is perfectly easy to bring any hive of bees through the winter; but to ensure the success of a very light stock, it is essential to keep it also very warm and dry. Feeding is absolutely necessary when you have taken more honey than the hive can afford, by the means of small hives or glasses. Such stocks as are intended to be kept through the winter should weigh twenty pounds or up- wards, at the end of September; but casts and late swarms seldom attain this weight, unless two or more should have been united. The composition for feeding consists of moist sugar and new beer, in the proportion of one pound of sugar to a pint of beer, simmered to the consistency of treacle: to be inserted into the hives by means of small troughs, at night, and removed the next morning early. Should a hive be very poor and weak, it is better to feed in larger quantities each time. . Feeding Machine.—The annexed improved machine for feed- ing bees, will suit all descriptions of hives:—Prepare a board a little larger than the bottom of the hive, in the centre of which make an opening about ten inches diameter; then form a frame of half-inch deal, to consist of four sides, each about twelve inches by three inches; make the angles firm with small wooden blocks, to which affix the before-mentioned board. A door should then be made in the side of the frame, sufficiently large to admit a deep plate or a small dish, to contain the food. By the use of this machine, the bees are fed quietly, and protected from the cold weather, and the intrusion of other bees. It is scarcely necessary to observe further, that the door of the machine should face such part of the bee-house as best suits your convenience. The dish of food to be placed under should be covered with a piece of thick paper the size of the plate or dish, pierced in holes, through which the bees will feed; and a quantity of short pieces of straw also put into the dish, will prevent the bees from daubing themselves. They should be fed at night, and the dish only taken away early on the following morning; to do this, you should cover your face and hands. The autumn, and early part of the spring, are times proper to examine if any hives require feeding ; but always commence before the stock is in absolute want of food, otherwise the bees will be so poor and weak as to be unable to come down. * . Honey.—Honey differs much, according to the season of the year when gathered; that obtained in the spring is of much the finest quality; the fragrance and richness of which depends greatly on the pasturage. To judge of the best honey, it should be of a bright pale colour, thick, and a little aromatic. To obtain it from the combs in its pure state, it must be left to run from them without pressing. The properties of honey are much esteemed, and have been noticed by an eminent French physician, Dr. Lemery, in a treatise on foods, in which he says, “Honey heats and strengthens the stomach, is of a leni- tive nature—produces nourishment, helps respiration, and is particularly good for those of cold and phlegmatic constitu- tions. - The newly invented double-topped straw hive, and the other hives described in this article, and every necessary apparatus connected with the apiary, may be obtained at the Repository, 175, Strand; but the following instructions are from Huish’s work on bees; and the Huish Hive, which differs entirely from the above, may be had at No. 205, Piccadilly. Huish's hive is of straw, and resembles a flower-pot inverted, as represented in the annexed figure, with a convex covering of straw also. When the top a is removed, several laths are seen, as in b, to which the bees attach their combs, and are prevented from getting up into the top by means of a net which covers the laths. c represents a lath and comb attached to it, which may be easily removed, according to the following instructions for September. $ January—The bees begin to shew some small degree of activity in this month, when the weather is fine, if they are well. The snow should be carefully brushed off the tops of the hives, and it will be of service to the bees to turn the hives carefully up when the day is warm, and admit a portion of pure air into them. Bad smells and bad air are as prejudicial as bad food to bees. If the bees shew symptoms of dysentery, salt and port wine should be mixed with their food, or diluted brandy. - February.—Bees should be well fed with the following syrup. A pint of ale, a pound of sugar, half an ounce of salt, boiled well, and carefully skimmed: when cold, this mixture will be of the consistence of honey. The stools should be cleaned this month, and sprinkled with salt. The mouth of the hive, which in September was contracted, in order to exclude insects and field mice, should now be enlarged, yet this should only be permitted when the weather is fine ; if a fall of Snow should again take place, it should be closed,—this should be effected so as to prevent the egress of the bees, but not so as to prevent a circulation of air. A piece of open canvass might be strained over a little frame, and fastened above the hole, which might be raised or lowered at pleasure. In the Huish hives, these slides are of tin. Water should be plentifully supplied in troughs, if no streamlet is at hand, pebbles being placed in it to serve as resting places for the bees. March.-If, as it frequently happens, the bees of a hive appear languid and weak, and the most generous food appears to be thrown away upon them, the queen of that hive is barren, and the cells are devoid of any fecundated eggs of the last season; they should therefore be joined to the next inferior stock in the apiary. To effect this, the top of the hive to which the bees are to be joined, must be cut off, and the combs laid bare; this is a nice operation, for with the greatest care, much damage will incur; the weak hive must then be well plastered to the lower one, and every crevice filled so as to permit no egress for the bees, except through the entrance of the lower hive. The bees should be fed in the evening, and in the morn- ing the surplus should be removed. The mouth of the hive may now be left at its usual size. Stock hives should be pur- chased this month. The hives should be kept warm, or shel- tered. Young bees may now be seen about the entrance of the hive; the old bees may also be observed cleaning them with their proboscis. April.—The business of the hive increases daily, and the sight of the first drone should be considered a holiday, as he is the harbinger of a swarm. New hives should be kept in store, to be at hand when wanted. All superfluous and rough straws should be carefully cleared from the interior of the hives, and holes, if any there are, should be stopped with putty or mortar. Singeing or friction will remove the straws—the former is per- haps the best method. The little speckled butterflies now hover about, to steal into the hives, that they may there deposit their eggs. These should be watched, and destroyed.—The queen wasp often appears this month, and should, if possi- ble, be destroyed. If a hive is attacked either by bees or wasps, the only real way to assist its inhabitants is, by remov- 2 D 102 B E E B E L DICTIONARY OF MECHANICAL SCIENCE. ing the hive far away in the evening, and putting an empty one in its place. Some hives will swarm in April, but this is considered rather early. May.—The bees now becoming very numerous in a health- ful hive, many of them fan at the entrance, to refresh their in- mates; besides which, small drops of perspiration may be seen on the board, and an increasing blackness also. The cluster- ing of the bees round the mouth of the hive for two or three days together, sometimes at the mouth of the hive, fore- tels the swarming; and if bees are carefully watched, two or three may be observed, and sometimes more, wandering about, and examining particular objects. The most usual time of swarming is between the hours of mine A.M. and two P.M. They never swarm while the day is clouded, or in high winds. Yet a sudden gleam of sunshine will oftentimes tempt them to choose their new habitation, even in inclement seasons. All the clatter made by pokers and shovels is absolute nonsense, and would tend rather to scare the bees than settle them; their flight should be watched, and when once they settle, the hive should, if possible, be held under them—a goose wing is of great service in brushing them off; but if they attach themselves to a twig which can be cut off, this should be done. The hive should be well rubbed inside with strong beer, sugar, and salt, as before described ; though it is the opinion of some apiarians, that no such preparation is necessary. A good swarm should weigh six pounds: its weight is easily ascertained by weighing the empty hive first. Should a hive appear destitute of drones, some must be caught as they are about to enter other hives, and at evening they must be placed at the entrance of the hive supposed to be destitute of them. June.—Second swarms take their flight this month; but they give no signs of their departure, and therefore should be well watched. A second swarm is not worth much, but two such swarms together make a good one. The two swarms may be swept into the same hive, and one of the queen bees will be killed by the strongest. But if the proprietor has skill and courage enough to do it, he should kill one of the queen bees himself. Second swarms may be returned to the parent hive in the following manner:—Place the back of a chair parallel with the entrance of the hive, spreading over it a table-cloth, then holding the hive, containing the second swarm, over this, give it a gentle tap or two; the bees will fall on it, and may be gently impelled to their old habitation by a feather or stick. A first swarm commences the construction of the comb in the middle of the hive ; the second swarm, at the sides. July.—The hives should be shaded this month from the intense heat of the sun, to preserve the wax, and consequently the honey. Some persons extract some of the comb at this season of the year. A bee entering the hive with honey, is of a cylindrical form, and of a glossy appearance. The bee with- out honey, is sun-broiled and wrinkled. When the latter appear numerous, and a correspondent proportion of bees without the pellets of wax are also seen, the hive to which they belong is in a decaying state. Those hives in which the drones are first destroyed, are of particular value. August.—In those counties where they suffocate the bees, the operation is carried into effect in this month, upon the suppo- sition, that the little creatures begin to live upon their stock; but this is erroneous: if the season is mild, they find food till October. The common spider commits great devastation this month, and care should be taken to destroy him. The entrance of the hive should also be closed, so as to prevent more than two bees entering at the same time, in order to exclude other robbing bees and wasps. The usual way, how- ever, is, to offer a reward for every wasp not destroyed. The humble-bee may also be considered an enemy, since it con- sumes four times the quantity of the mellifluous juice of flow- ers than the hive bee. The hives should, not be molested during this month, more than can be helped, or than is neces- sary for their preservation against the attacks of their enemies. September.—This is the month in which many apiarians take a part of the honeyed store, and the following is the most approved method for effecting this difficult task:—In the first place, no hive should be incommoded by sticks. Presuming that this is not the case, the hive should be carefully turned three parts of copper and one of tin. up; some tobacco being at hand ready for fumigation, the bees will then lose all their courage, and retreat into the corners of the hive; and if they recover from their stupor, a second application of the tobacco will quiet them. The comb should then be carefully cut out, but sparingly. The middle combs should not be touched. When two weak hives are to be joined, Mr. Huish recommends that both should be stupe- fied by fumigation, and one of the queen bees carefully dis- covered and killed, the hive to which she belonged being carefully swept into the other. It is the opinion of some apiarians, that the bees should be assisted in the destruction of the drones. The hive should be carefully examined, the stool cleaned, and strewed with salt. Contract the entrance, and plaster the hive to the stool, to keep out all foreign enemies. October.—Bees should be well fed this month, with the syrup mentioned in February. The tops of the hives should be examined, and protected from all damp and inclemency of the weather. Cleanliness is absolutely necessary to the prosperity of bees. The entrance should be again contracted, so as to admit only one bee. * November.—The hives should be carefully attended to, and care should also be taken that they have plenty of food. This may be ascertained by occasionally weighing the hive upon the board on which it stands, and marking the decrease of weight. Great cold will affect the bees, and reduce them to a state of torpor, which will end in death, unless relieved by a removal to a warmer situation. Every scattered benumbed bee should be attended to, collected, and when restored to animation by gentle warmth, should be placed at the mouth of the hive, when it will gladly enter. They should be collected in a handkerchief; not in any glazed substance. The field mouse should be watched, and all other vermin and insects; and the hives, if in an exposed situation, should be fastened by a rope to the stand, lest the wind, which frequently happens, should blow them down. December, All that the apiarian has to attend to this month, is to keep his hives clear from snow, and confining the bees to their dwelling; and the less they are disturbed in cold weather, the better, since they are kept alive in winter by a reciprocity of animal heat, which is of course diminished if they are com- pelled to separate, or are shaken. BELL METAL, of which bells are made, is composed of See Foun DRY. The Diving Bell.—To illustrate the principle of this ma- chine, take a glass tumbler, plunge it into water with the mouth downwards; you will find that very little water will rise into the tumbler; which will be evident, if you lay a piece of cork upon the surface of the water, and put-the tum- bler over it; for you will see, that though the cork should be carried far below the surface of the water, yet that its upper side is not wetted, the air which was in the tumbler having prevented the entrance of the water; but as air is compressible, it could not entirely exclude the water, which, by its pressure, condensed the air a little. The first diving-bell of any note was made by Dr. Halley. It is most com- monly made in the form of a truncated cone, the smallest end being closed, and the larger one open. It is weighted with lead, and so suspended that it - may sink full of air, with its open base downwards, and as near as may be parallel to the horizon, so as to close with the surface of the water. Mr. Smeaton's diving-bell was a square chest of cast iron, four feet and a half in height, four feet and a half in length, and three feet wide, and afforded room for two men to work in it. It was supplied with fresh air by a forcing pump. This was used with great success at Ramsgate. Other contrivances have been used for diving-bells. • , The first diving-bell we read of in Europe was tried at Cadiz, by two Greeks, in the presence of Charles W. and 10,000 spectators. It resembled a large kettle inverted. The first * . B E L B E L DICTIONARY OF MECHANICAL SCIENCE. 103 person who brought the diving-bell into vogue with us was ‘Phipps, the American blacksmith, in the reign of Charles II., and who, from the fortune he acquired from a Spanish ship, to which he went down, laid the honours of the Mulgrave family. The following is the most useful purpose to which the diving-bell has been applied. - Diving-Bell at Port Patrick.-The diving-bell, or rather the improved instrument now in use at Port Patrick, is neither more nor less than a square cast-metal frame, about 8 feet high, 22 feet in circumference, and weighing upwards of four tons. This frame is, of course, open below, and at the top are twelve small circular windows made of very thick glass, such as are sometimes seen used on board of ships. These windows are so cemented or puttied in, that not a bubble of water can pene- trate; and when the sea is clear, and particularly when the sun is shining, the workmen are enabled to carry on their sub- marine operations without the aid of candles, which would consume nearly as much air as an equal number of human beings. In the inside of the bell are seats for the workmen, with knobs to hang their tools on ; and attached to it is a strong double air-pump, which is a mighty improvement on the old-fashioned plan of sinking barrels filled with air. From this pump issues a thick leathern tube, which is closely fitted into the bell, and the length of which can easily be proportioned to the depth of water. As may be supposed, the bell is sus- pended from a very long crane, the shaft of which is sunk to the very keel of a vessel, purchased and fitted up for the purpose, and which is, in fact, a necessary part of the diving apparatus. On the deck of this vessel is placed the air-pump, worked by four men, with an additional hand to watch the signals. When about, therefore, to commence operations, the sloop is moved to the outside of the breakwater, the air-pump put in motion, the crane worked,and then go down the aquatic quarrymen. From its weight and shape, the machine must dip perpendicularly ; while the volume of air within enables the workmen to breathe, and keeps out the water. On arriving at the bottom, the divers are chiefly annoyed with large beds of sea-weed, although, from the inequalities of the channel at Port Patrick, and the partially uneven manner in which the ledges of the bell occa- sionally rest on the rocks, it is impossible to expel the water altogether; and this, it is presumed, is the reason why it is dangerous to descend in rough or squally weather, when the heaving and agitated deep would be apt to dash in at the smallest cranny. To guard against the effects of several hours’ partial immersion in water, the men are provided with large jack- boots, caps of wool, and coarse woollen jackets. They also observe the precaution of stuffing their ears with cotton, as the constant stream of air which descends from above, occasions, at first, an uneasy sensation, and is even apt to produce deaf- ness. The chief submarine artist came from Holyhead; and out of 180 masons, carpenters, and labourers, only one man, it is said, volunteered to assist him. A respectable and inge- nious gentleman, who had been down in the bell, stated, that he felt no inconvenience whatever; but the air-pump workers, among whom were made some minute inquiries, shook their heads at this piece of information, and hinted, that the volun- teer-diver had often felt a little queerish, and, for one thing, “ had taken his victuals very badly.” Here, then, we have two or three men working with perfect ease and safety 20, 25, and sometimes 30 feet below water. In carrying out the new pier, it is necessary to make a bed for the foundation stones, which would otherwise be left at the mercy of the waves—and this, in a word, is the duty of the divers. With picks, ham- mers, jumpers, and gunpowder, the most rugged surface is made even, and not only a bed prepared for the huge masses of stone which are afterwards let down, but the blocks them- selves strongly bound together with iron, and cement. The divers, like other quarrymen, when they wish “to blast,” take good care to be put out of harm's way. By means of a tin tube, the powder is kept quite dry, and a branch from the larger cavity, hollow and filled with an oaten straw, is length- ened to the very surface of the water before the fuse is lighted. In one or two cases the powder has failed to explode, and it is very teasing for the men, after three or four hours' hard work below water, to be compelled to descend again, for the sole purpose of repeating the blasting process. - BELLEROPHON, a name sometimes given to the constel- lation Pegasus. BELLOWS, an instrument constructed for the purpose of alternately drawing and expelling air. In the common culinary bellows the air rushes in at a hole or holes at the bottom, called feeders, over which is a flapping valve, and is expelled through a conical pipe called the nozzle, by means of a kind of mechanism too well known to require description here. Dr. Gregory observes, that it is not the impulsive force of the blast that is wanted in most cases, but merely the copious supply of air to produce the rapid combustion of inflammable matter; and the service would, in general, be better performed if this could be done with moderate velocities and extended Surface. What are called air-furnaces, where a considerable surface of inflammable matter is acted on at once by the cur: rent which the mere heat of the expended air has produced, are found more operative, in proportion to the air expended, than blast-furnaces animated by bellows. There is, indeed, a great impulsive force required in some cases; as, for blowing off the scoriae from the surface of silver or copper in refining furnaces, or for keeping a clear passage for the air in great iron furnaces. But, in general, we cannot procure this abundant supply of air in any other way than by giving it a great velo- city by means of a great pressure or impulse; the air is admitted into a very large cavity, and then forcibly expelled from it through a small orifice. The method of producing a continual blast by a centrifugal force has been long known. Anacharsis, the Scythian, is recorded as the inventor of bellows. But the first bellows acting upon this principle, of which we have a distinct account, is that invented by M. Teral, in 1729, and represented in the following figure, where A B is a cubical box, with a top rather arched : to this box is adapted a hollow pyramidal frustum C, at the extremity of which is the tube or nozzle D; the capacity of the pyramid not being separated from that of the box. This box contains an arbor or shaft carrying vanes, as G F, posited horizontally, and which are here placed, as it were, out of the box, that their shape and number may be seen. The ends of the arbor run in a proper collar on each side of the box, and One end, as F, passes through the side of the box, and carries a pulley : over this pulley passes a cord or band, which also runs round part of a wheel H I, situated at some distance from the bellows, and which is turned by the handle M. Thus it will be manifest, that as this handle turns the wheel HI, it will, by means of the band, turn the pulley F and the arbor and vanes, with a velocity which will be to that of the wheel as the radius of the wheel to that of the pulley. Hence the greater the diameter of the wheel, and the less that of the pulley, the more rapidly will the exterior air (which enters by small holes h h, into the top of the box,) be driven by the vanes, and com- pressed into the truncated pyramid c, and thence expelled at D, in a continued blast; which will likewise be the more violent the greater the action at the handle M. This machine, being very simple, is easily constructed, and at a small expense: Another bellows, furnishing a uniform blast, is described as follows:—One cylinder is made to deliver its air into another cylinder, which has a piston exactly fitted to its bore, and 104 B E. L. B E L DICTIONARY OF MECHANICAL SCIENCE, The blowing cylinder A B C D, its piston P worked arched loaded with a sufficient weight. T (as represented in the figure below.) has. tº iy a rod NP. connected by double chains with the ſ ſ H V2 Aſ -P P | F ré–3) S_r . |_+ =3 g- H i IK - =T head of the working beam NO, moving round a gudgeon at R. The other end O of this beam is connected by the rod O P with the crank PQ of a wheel-machine; or it may be con- nected with the piston of a steam-engine, &c,. &c. The blow- ing cylinder has a valve or valves E in its bottom, opening inwards. There proceeds from it a large pipe CF, which enters the regulating cylinder G H K I, and has a valve at top, to prevent the air from getting back into the blowing cylinder A B C D. It is evident, that the air forced into this cylinder, G. H. K.I, must raise its piston L, and that it must afterwards descend, while the other piston is rising. It must descend uniformly, and make a perfectly equable blast. We may observe, however, that if the piston L be at the bottom when the machine begins to work, it will be at the bottom at the end of every stroke, if the tuyere T emits as much air as the cylinder A B C D furnishes; nay, it will lie a while at the bottom, for, while it was rising, air was issuing through T. But as this would make an interrupted blast, it is prevented thus: The orifice T must be lessened; yet then there will be a surplus of air at the end of each stroke, and the piston L will rise continually, and at last get to the top, and allow air to escape. But it is possible to adjust circumstances, so that neither shall happen. This is done easier by putting a stop in the way of the piston, and putting a valve on the piston, or on the conducting pipe K S T, loaded with a weight a little supe- rior to the intended elasticity of the air in the cylinder. There- fore, when the piston is prevented by the stop from rising, the shifting valve, as it is called, is forced open, the superfluous air escapes, and the blast preserves its uniformity. The Hydraulic Forge Bellows, of Mr. J. C. Hornblower, a very ingenious contrivance, is thus described. This invention is shewn in the following engraving :-A the plunger, or work- ing part of the bellows, 18 inches square within, which receives the air by a valve in the hinder part opening inwards, which at the stroke by the rockstaff E throws it down the tube indi- cated by the dotted lines, which has a valve opening into the reservoir D, whence it is led to the tuyere by the pipe P. Length of the plunger 20 inches, stroke nine inches. Diameter of P three inches; of the nozzle 0-6. The whole is placed in a pit or cistern, having water sufficient to rise to the lower end of the tube where the valve hangs; this tube is the only com- munication between the upper part and the reservoir D: when as much water is poured in round the working part, over the wash-boards, as will rise within five inches of the upper edge of them, the bellows is ready for use. The little frame-work serves to keep it from rising, and affords a convenient support for the balance and the rockstaff. The area of the pit or cis- tern ought to be at least twice as much as that of the plunger A. A very striking difference between the effect of this bellows H. } and a common leather- ed 30-inch bellows in the same shop, is the ſollowing. The lea- thered bellows throws considerably more air to the fire, and its noz- zle, compared with this, is as ‘73 to 60 in dia- meter, but it does not produce so great an effect in bringing on the heat, and the noise of this is so great as almost to drown that of the common One. The only difference in other respects is, that in the hydraulic bel- lows the pipe goes un- der ground for about eight feet, and the con- ducting pipe of the other comes down about the same dis- tance from the shop above. - When bellows are made more than usual- ly large, for extensive furnaces, they have been frequently work- ed by water-wheels. But iron furnaces have, of late, been constructed of such magnitude, that no leather bellows could be made sufficiently capacious; and hence large forcing pumps have been substituted for them. We shall, under the article Forge, describe the Carron engine constructed by Smeaton. Hydrostatic Bellows, (as represented in the annexed figure.) is a machine for illustrating the upward pressure of fluids. It consists of two thick boards E F, C D, about 16 or 18 inches diameter, covered or connected firmly with pliable leather round the edges, to open and shut like common bellows, but without valves; a pipe A B, about three feet high, is fixed into the bellows at B, Now let water be poured into the pipe at A. and it will run into the bel- lows, gradually separating the boards by raising the upper one. Then, if several weights (3 hundred weights, for instance,) be laid upon the upper board, the water being poured in at the pipe till it be full, will sustain all the weights, though the water in the pipe, should not weigh a quarter of a pound. For the narrower the pipe the better, beyond certain limits, provided we may make it long enough, the proportion being always this: As the area of the orifice or section of the pipe, To the area of the bellows’ board, E F; So is the weight of water in the pipe A G, To the weight it will sustain on the board C. D. For the fluid at B, the bottom of the tube, is pressed with a force varying as its altitude A B ; and this pressure is commu- nicated horizontally to all the particles in the space FE, and then distributed equally throughout the fluid in the bellows; consequently, the pressure upwards at FE is equal to the weight of a cylinder of the fluid whose base is F E, and altitude A B; while the actual weight of water borne up is only that of the cylinder, whose base is FE, and height B G ; and hence no weights laid upon CD that do not exceed the weight of a • * * * * * g º sm • * * * * * * * * * * * * * -----— --. —-2 A. B E R. B E R. 105. i) ICTIONARY OF MECHANICAL SCIENCE. cylinder of the fluid, whose base is EF and altitude A G, will I disturb the equilibrium. Bellows, or Water Blowing-Engine, is a machine in which the stream of air is supplied by the flowing of the water, and it has been long employed at the iron works of Poullaouen in France. The shower of water, in its descent through the verti- cal pipe of the machine, carries down a column of air along with it, (upon the principle of the lateral adhesion of fluids,) in the same manner as a shower of rain on the surface of the sea, produces that temporary blast of wind which the seamen term a squall. The effects of this machine in producing a blast of air, are inferior to that of the steam-engine ; but in situations which afford a plentiful supply and a sufficient fall of water, it may frequently be employed with advantage. BELTS, Fascia, in Astronomy, zones or girdles, surrounding the planet Jupiter, more lucid than the other parts of his body, and terminated by parallel straight lines, being sometimes broader and sometimes narrower, varying both in magnitude and position. Dark spots have frequently been observed in Jupiter's Belts, one of which is permanent, and by means of which the diurnal revolution of this planet has been ascer- tained. See Phil. Trans. No. 10 and No. 11, vol. lxiii. Some astronomers suppose the belts to be seas, which alternately cover and leave bare vast tracts of this planet; and that the spots are gulfs in those seas, probably as large as our ocean, sometimes full and at others dry. Other hypotheses have been advanced by different astronomers, which, however, are all merely conjectures, and therefore excite but little interest. These belts were first observed at Naples by Zuppi and Bar- toli, two jesuits, and afterwards by Campani and Huygens. Cassini observed, also, three dark straight parallel belts on the disc of Saturn ; and something of a similar kind has been seen indistinctly on the planet Mars. BENDING, the reducing a body to a curved or crooked form. The bending of boards, planks, &c. is effected by means of heat, whether by boiling or otherwise, by which their fibres are so relaxed, that they may be bent into any figure at plea- sure. Dernoulli has a discourse on the bending of springs or elastic bodies, and Amonton gives several experiments on the bending of ropes. BENITHNASH, a name sometimes given to the last star in the tail of Ursa Major. . . BERKELEY, DR. GeoRG e, a celebrated divine and philo- sopher, was born at Kilarin in Ireland, 1684, and died at Oxford, 1753, in the 69th year of his age. He was author of several works on theology, mathematics, and metaphysics. BERNE MACHINE, (as in the following figure,) for rooting up trees, the invention of Peter Sommer, of Berne, consists of top and bottom by strong iron hoops. order. three parts, the beam, the ram, and the lever. The beam, A B C, No. 1, of which only one side is seen in the figure, is com- posed of two stout planks of oak, three inches thick at least, and separated by two transverse pieces of the same wood, at A and C, about three inches thick: these planks are bored through with corresponding holes, to receive iron pins, upon which the lever acts between the two sides of the beam, and which is shifted higher and higher as the tree is raised, or rather pushed out of its place: the sides are well secured at the - The iron pins on which the lever rests, should be an inch and a quarter, and the holes through which they pass, an inch and a half, in diameter. The position of these holes is sufficiently indicated by the figure. The foot of the beam, when the machine is in action, is secured by stakes represented at G, driven into the earth. The ram, D, which is made of oak, elm, or some other strong wood, is cap- ped with three strong iron spikes represented at f which take fast hold of the tree. This ram is six or eight inches square, and a slit is cut lengthwise through the middle of it, from its lower end at K, to the first ferule a, in order to allow room for the chain g h to play round the pulley K, which should be four inches thick, and nine inches in diameter. This ram is raised by means of the chain g h, which should be about ten feet long, with links four inches and three-quarters in length, and an inch thick. One end of this chain is fastened to the top of the beam at C, while the other, after passing through the lower part of the ram, and over the pulley K, terminates in a ring or link represented in No. 3; the two ears, m, n, of which, serve to keep it in a true position between the two planks of the beam. In this ring, the hook p is inserted: the hook is represented in profile, No. 2, where F is the part which takes hold of the ring. But it must be observed, that the parts of this machine represented in Nos. 2, 3, are drawn on a scale twice as large as the whole engine. The hook F, No. 2, should be made of very tough iron, as well as the handle D, and the arch E C. This handle should be two inches thick at z, where it joins to the hook, and the thickness gradually lessen by degrees up to the arch, which need not be more than half an inch thick. On each side of the pin z is a semicircular notch a y, which rests alternately on the pins when the machine is worked. The hole D, and the arch EC serve to fix a long lever of wood EF, No. 1, by means of two iron pins; and by this contrivance, the lever is either raised or depressed at pleasure, in order to render the working of the machine easy in whatever part of the beam the lever may be placed ; for without this contrivance, the extremity of the lever E F would, when the handle is near the top of the beam, be much higher than men standing upon the ground could reach. It must, however, be remembered, that the lever is often shortened by this contrivance, and con- sequently its power lessened. The machine is worked in the following manner:—It is placed against a tree, in the manner represented in the figure, so that the iron spikes at f may have hold of the tree, and the end of the beam. A be supported by stakes represented at G. The iron handle, No. 2, is placed in the opening between the two planks of the beam, and the wooden lever fixed to it by means of the iron pins already mentioned. The hook F takes hold of the chain, and one of the iron pins is thrust into the outer row of holes, by which means the outer notch a will rest on the pin, which will be now the centre of motion; and the end of the lever E, No. 1, being pressed downwards, the other notch y, No. 2, will be raised, and at the same time the chain, and consequently the ram. The other iron pin is now to be thrust into the hole in the inner row, next above that which was before the centre of motion, and the end of the lever E elevated or pushed upwards, the latter pin on which the notch y rests, now becoming the centre of motion. By this alternate motion of the lever, and shifting the pins, the chain is drawn upwards over the pulley K, and | consequently the whole force of the engine exerted against the tree : there is a small wheel at L, in order to lessen the friction of that part of the machine. From this account the reader will very easily perceive, that the machine is nothing more than a single pulley compounded with a lever of the first and second It must, however, be remembered, that as the push of the engine is given in an oblique direction, it will exert a greater or lesser force against the horizontal roots of the tree, 2 E #56 *B I N ' DICTIONARY OF MECHANICAL SCIENCE. B I N in proportion to the angle formed by the machine with the plane of the horizon, and that the angle of 45° is the maximum, brºthat, when the 'machine will exert its greatest force against "the horizontal roots of the tree. BERNOULLI, the name of several excellent mathemati- “cians of France and Switzerland. . BERYL, a pellucid gem of a bluish green colour, found in the East Indies, Peru, and Silesia. This gem assumes either the ‘pebble or columnar, or crystal form. To imitate beryl, artists 'add to 20 lbs. of crystal glass made without magnesia, 6 ounces of calcined brass or copper, and a quarter of an ounce of pre- spared zaffre. . BIENNIAL PLANTs, are those which endure two years; as, of esculents, the cabbage, savoy, carrots, parsnips, beet, onion, leek; of flowers, carnation, hollyhock, wallflower, &c. | | | BILBOES, long bars or bolts of iron with skackles sliding: on them, and a lock at the end, used to confine the feet of prisoners in a manner similar to the punishment of the stocks. The offender is laid in irons, which are more or less ponderous; according to the nature of the offence of which he is guilty. BILGE, or Bild Ge, that part of a floor in a ship which, approaches nearer to an horizontal than to a perpendicular direction, and on which the ship would rest if laid on the ground : hence, when a ship receives a fracture in this place, she is said to be bilged, or bulged. Bilge is also the largest circumference of a cask, or that which extends round by the bung-hole. - Bilge-water, the rain or sea-water which occasionally enters the lower apartments of a ship, whence running down to the : floor, it remains in the bilge of the ship, till pumped out, by reason of her flat-bottom, which prevents it from going to the well of the pump, and is always (if the ship does not leak) of a dirty colour, and disagreeable smell. BILLION, in Numeration, the sum of a million of millions, or 10000-0000:0000: this term, as well as those of trillion, qua- tillions, &c. are introduced for the more readily expressing in words, or enumerating, a number consisting of many figures; but they have been differently employed by different writers; the French mathematicians understanding billion to mean thou- sands of millions, and the English millions of millions; thus, in ;IBezout's “Course of Mathematics,” and the “Encyclopédie Méthodique,” the place of billions is said to be the tenth from the right towards the left, whereas we make it in our arithmetics the thirteenth; and it is singular, that this word is not found in any. English dictionary. Mr. Bonnycastle, in his arithmetic, uses the phrase bi-million or billion, tri-million or trillion, which seems to be the probable derivation of these terms; and admit- ting this, there can be no doubt, from analogy, that bi-million or billion means a million times a million, the same as biquad- ratic means a quantity produced from the multiplication of two quadratics. The French have, however, decidedly the advan- tage in point of simplicity. - BIMEDIAL LINE, in Geometry, is the sum of two medials. Thus, when two medial lines, commensurable only in power, and containing a rational rectangle, be compounded, the whole: shall be irrational with respect to either of the two ; and is called, by Euclid, a first bimedial line. But if two medial lines, commensurable only in power, and containing a medial rect- angle, be compounded, the whole will be irrational ; and is called a second bimedial line. Euclid, lib. x. prop. 38 and 39. BINOCLE, or BINocula R Telescope, is a telescope to which both eyes may be applied; and, consequently, the same object observed at the same time with both. It consists of two tubes, with two sets of glasses of the same power, and adjusted to the same axis; which has been said to exhibit objects larger and more distinct than a single or monocular glass. But this is probably only an illusion, occasioned by the stronger impres- Sion which two equal images, alike illuminated, make upon the eyes. There are also microscopes of the same construction, but they are very seldom used. BINOMIAL, in Algebra, is a large quantity consisting of two terms or names, and connected by the sign + plus, – mi- nus, or = equal ; thus, a + b, a - b, a = b, are all binomials; the difference a - b, being also frequently called a residual; and by Euclid, apotome. The terms binomial and residual are said to have been introduced into algebra by Recorde, in 1557 ; f |5th Power... (a + b) as +5 a b + 10 a.3b2 + 10 aºb% + 5ab" b5 and they have since been very commonly employed in various ways. Thus we say, Binomial Curve, Equation, Surd, Theo- rem, &c. r * – # BINoMIAL Theorem, is a general algebraical expression or formula, by which any power or root of a quantity of two terms is expanded into a series. This is also commonly called the Newtonian theorem, or Newton’s binomial theorem, on account of his being commonly considered as the inventor of it, as he undoubtedly was, at least in the case of fractional and negative indices ; which includes all the other particular cases of powers, divisions, &c. This celebrated theorem, as proposed in : its simplest form, is this :—Let a + b be raised to the fourth power. Mode of The Powers. | Expressing Powers Expanded. them. |Square..... (a + b)? |a” + 2 ab -- b% | | | Cube . . . . . ... (a + b)? |a" + 3° ab + 3 abº + bº 4th Power... (a + b)" |a' + 4a3b + 6 a.º. b3 + 4 abº + bº + 6th Power... (a + b) |a| + 6a, b + 15 abº +20 aºbº + 15 as bº + 6 abº + bº. &c. - &c. &c. The first term a is raised to the 6th power, and the second term b to the same power. In all the intermediate terms the powers of a decrease, and the powers of b increase, by unity, in each successive term. In each case, the co-efficient of the second term is the same with the index of the given power. Thus, in the square it is 2, in the cube 3, &c. If the co-efficient of a in any term be multiplied by its index, and the product divided by the number of terms to that place, the quotient will give the co-efficient of the next term. - - Thus are we furnished with a general rule for raising the binomial a + b to any power, without the process of actual multiplication. For were we required to raise a + b to the eighth power, the rule just laid down shews us, that The first term is...... • - - - - - - - - - - - - - - - - - - - . . dº The second . . . . . . . . . . . . . . . . . . . . . . . . . . . . .... 8a, b The third . . . . . . . . . . . . . A g 8 . 7 as bº → .28 agbº 2 The fourth. . . . . . . . . . . . . . *** ** = 56*. 56 The fifth. . . . . . . . . . . . . . . . *** a w = 70aº. 70 × 4 The sixth . . . . . . . . tº dº ſº e º ſº º *; 1 asbB = 56 a.3b6 56 × 3 The seventh . . . . . . . . . . . . . *; a2b0 = 28 a.2 b8 28 2 The eighth . . . . . . . . . . . . . . ** alº - saw The ninth...... & e º s º is e e º e s sº e º e s e o e a s I- bº, When the number of terms is even in the resulting quantity, the co-efficients of the two middle terms are the same; and, in all cases, the co-efficients increase as far as the middle term, and then decrease precisely in the same manner, till we arrive at the last term. Guided by this law of the co-efficients, we need only calculate them as far as the middle term, and then set down the remaining ones in an inverted order. - Thus, in Q The first five º 1, 9, 36, 84, 126 : a – y $ And the last five . . . . . . . . . . . . ) 126, 84, 36, 9, 1. This rule, exhibited in its most general form of the Newtonian Binomial Theorem, is thus read: Suppose we were required to raise the binomial a + b to any power denoted by n : From the principles already laid down, B I R. B I R. 407 DICTIONARY OF MECHANICAL SCIENCE. The first term would be wº. The second. . . . . . . . . . . . na”-'b. | m (24 – 1 i The third ............” 2 **-*. The fourth. . . . . . . . . . . . n (n — }; t=*-*. - º — 2. — 3 The fifth . . . . . . . . . . . . . . n (n. 2. ) (n — 3) an--4b*. The last ... . . . . . . . . . . . b.". * (m — 1 —t)(n–2) Or, (a + b)" = a + na”-b +*=le ºr nº-ºº-º) an—3b3 -- n(n gºsº 1) ##!º- *lan-b + &c. s tº dº e s is e e + b”. By the same process, (a — b)*::= a”— na”-'b + n(n-1) an–202 n(n - 1) (n − 2) 2.3 -alternately + and —. BIQUADRATIC Root, is the fourth root of any proposed quantity; thus 2 is the biquadratic, or fourth root, of 16. The biquadratic root of a number is found by extracting the square root of it, and then the square root of that root; which last result will be the root sought. Thus, the fourth root of 20736. is found as follows: - - M 20736 = 144, the square root, : V 144 12, the 4th root sought; i and so on for any other number. - * BioUADRATIC Equation, is an equation of the fourth degree, or in which the unknown quantity rises to the fourth power; thus, a: + a ac” + b a.” + c a' + d = 0, { is a biquadratic equation, in which a, b, c, and d, may be any numbers whatever, positive or negative, or any of them equal to zero or 0. ; A biquadratic equation is the highest order of equation that: admits of a general solution; all beyond this being resolvable only in particular cases. For the solution of equations of the , fourth degree, different solutions have been proposed by several authors. - BIQUINTILE Aspect of the Planets, is when they are dis- tant from each other 1449, or twice the fifth part of 360°. BIRCH, Bark of, is used in Russia as we use tiles to cover houses; and among the Indians of America, it covers the slender ribs of their canoes. Birch leaves are of use in the dropsy, itch, &c. - - . BIRDS, in Heraldry, represent a contemplative or active life, and are emblems of expedition, liberty, readiness, and fear. Bi Ros. The skeleton or bony frame of birds is lighter than. that of quadrupeds, and is calculated for the power of flight; 3the spine is immoveable, the neck lengthened and flexible; the breast-bone very large, with a prominent keel down the middle, and formed for the attachment of strong muscles. The bones of the wings are analogous to those of the fore-legs in quadru- peds, but the termination is in three joints, of which the exte- rior one is very short. The legs are analogous to the hind-legs in quadrupeds, and terminate in general in four toes, three of which are commonly directed forwards, and one backwards; in some birds there are only two toes, in others, only three. All the bones in birds are much lighter than in quadrupeds. The feathers with which birds are covered, resemble the hair of quadrupeds, being composed of a similar substance in a dif- ºferent form. Beneath the general plumage, the skin in birds is covered with a much finer feathery substance, called down. The throat, after passing down to a certain distance, dilates into a large bag, answering to the stomachin quadrupeds: it , is called the crop, and its great use is to soften and prepare the “food taken into it, for passing into another receptacle, called the gizzard. This powerful stomach consists of two strong muscles, lined and, covered with a strong coat furrowed on the inside. In the birds of prey, or accipitres, this is wanting, the a”—ºbº + &c.; the signs of the terms being tºº * | Same general plan as in quadrupeds. plovers, and snipes. the top, and covered with a soft skin; and the feet webbed, as ducks and geese. • stomachibeing allied to that of quadrupeds. In this receptacle, the food is ground, and reduced to a pulp. The lungs of birds differ from those of quadrupeds in not being loose in the breast, but fixed to the bones; they consist of a pair of large Spongy bodies, covered with a membrane, which is pierced in | several places, and communicates with large air-bags, dis- | persed about the cavities of the body. The eyes of birds are more or less convex in the different tribes; and in general, their sight is more acute than that of most other animals. Their ear, though internal, is constructed very nicely, on the Their organs of motion are two wings and two legs; and they are destitute of ex- ternal ears, lips, and many other parts which are important to quadrupeds. Birds are produced from eggs, which vary in number, size, and colour, but are always covered with a hard shell, and for the most part deposited in an artificial nest, and hatched by the general warmth of the parent sitting upon them. Linnaeus has divided this class into six orders:—1. Accipi- tres, hawks, &c.; 2. Picae, pies, &c.; 3. Passeres, sparrows, &c.; 4. Gallinae, poultry, &c.; 5. Grallae, herons, &c.; 6. An- Seres, geese, &c. The orders of birds are these:—I. Land Birds.—1. Rapaci- ous birds have the upper mandible hooked, and an angular projection on each side near the point, as the eagles, hawks, and owls. 2. Pies, have their bills sharp at the edge, some. what compressed at the sides, and convex at the top, as the crows. 3. Passerine birds, have the bill conical and pointed, and the nostrils oval, open, and naked, as the sparrow and linnet. 4. Gallinaceous birds, have the upper mandible arched, and covering the lower one at the edge, and the nostrils arched over with a cartilaginous membrane, as the common poultry, turkeys, &c. II. Water Birds,-5. Waders, have a roundish bill, a fleshy tongue, and the legs naked above the knees, as the herons, 6. Swimmers, have their bills broad at BIRDS, To Preserve. The preserving of beautiful birds, with which some foreign countries abound, so as to retain their natural form and position, as well as the beauty of their colours and plumage, must be attended to with great care, lest they should be destroyed by insects, which has often been the case, to the great disappointment of the naturalist. After dissecting all the fleshy parts from the bones, and removing the entrails, eyes, brains, and tongue, the cavities and inside of the skin should be sprinkled with the following antiseptic powder. Muriate of mercury . . . . . . . . . . . . . . . . . . . . . ... 2 oz. Calcined nitrate of potass . . . . . . . . . . . . . . . . . . 2 sulphate of alumine . . . . . . . . . . . . . . . 2 Sulphur . . . . . . . . . . . . . . . . . . . . . . . . . . tº e º 'º e º 'º a 4 Camphor . . . . . & a tº e º & & © tº s is e a e º e º e • - - - - - - - - - - 2 Pulverized black pepper............ * - e - e º 'º º ºs 8 — tobacco . . . . . . . . tº º º is is e º 'º e g g g º ºs e e 8 Mix the whole together, and keep it in a glass vessel, stopped up very close. In Guiana, the number and variety of beauti- ful birds is so great, that several persons in the colony advan- tageously employ themselves in killing and preserving these animals for the cabinets of the naturalists in the different parts of Europe. The method of doing this, as related by Mr. Bancroft, is to put the bird which is to be preserved, in a pro- per vessel, and cover him with high wines, or the first distilla- tion of rum. In this spirit he is suffered to remain for twenty- four or forty-eight hours, or longer, according to his size, till it has penetrated through every part of his body. When this is done, the bird is taken out, and his feathers, which are noways changed by this immersion, are placed smooth and regular. He is then put into a machine made for the purpose, among a number of others; and his head, feet, wings, tail, &c. are placed exactly agreeable to life. In this posture they are all placed in an oven moderately heated, where they are slowly dried, and will ever after retain their natural position, without danger of putrefaction. - * To make Pictures of Birds, by Means of their own Feathers.- Get a thin board or panel of deal, or wainscot, well seasoned, 108 B I T B L E DICTIONARY OF MECHANICAL SCIENCE. that it may not warp. Paste white paper over it, and let it dry. Take any bird you would represent, and draw its outline on the paper in the attitude you desire, and of the full size, adding what landscape, back ground, &c. you wish. This outline, so drawn, is afterwards to be filled up with the feathers from the bird, placing each feather in that part of the drawing corresponding to the part of the bird it was taken from. Cover now the representation with several coats of strong gum water, letting it dry between each coat till it is of the thickness of a shilling. When your ground is thus prepared, take the feathers off from the bird, beginning at the tail or points of the wings, as you must work towards the head. These feathers are prepared by cutting off all the downy part; and the larger feathers have the insides of their shafts pared off, to make them lie flat. To lay them on, use a pair of small pliers to hold them by ; and moistening the gummed ground with water, place each feather in its matural and proper situa- tion. Keep each feather down, by putting a small leaden weight upon it, till you have another prepared to lay on. Be careful not to let the gum come through the feathers, as it smears them, and, sticking to the bottoms of the weights, will be apt to pull the feathers off. When you have put on all the feathers, cut a piece of round paper, and colour it like the eye, which you may stick in its place; but the best way is to get eyes made of glass. The bill, legs, and feet, must be drawn and coloured from nature. When it is finished and adjusted to your mind, lay a sheet of paper upon it, and upon that a heavy weight to pressit; which must remain till the whole is quite dry. BISECTION, the division of a quantity into two equal parts. BISSEXTILE, or LeAP Year, in Chronology, a year con- sisting of 366 days, happening once every four years, by reason of the addition of a day in the month of February, to recover the six hours which the sun spends in his course each year, beyond the 365 days ordinarily allowed for it. The day thus added is also called bissextile; Julius Caesar having ap- pointed it to be introduced, by reckoning the twenty-fourth of February twice; and as this day, in the old account, was the same as the sixth of the calends of March, which had been long celebrated among the Romans on account of the expulsion of Tarquin, it was called “bissertus calendas Martii;” i.e. twice the 6th of the calends of March ; and from hence we have derived the name bissextile. • By the statute de anno bissertile, 21 Henry III. to prevent misunderstandings, the intercalary day, and that next before it, are to be accounted as one day. - The astronomers concerned in reforming the calendar, by order of Pope Gregory XIII. in 1582, observing that the bis- sextile in four years, added forty-four minutes more than the sun spent in returning to the same point of the zodiac, and computing that these supernumerary minutes, in 133 years, would form a day; to prevent any changes being thus in- sensibly introduced into the seasons, directed, that in the course of 400 years, there should be three bissextiles re. trenched; so that every centesimal year, which, according to the Julian account, is bissextile or leap year, is a common year in the Gregorian account, unless the number of centuries can be divided by four without a remainder. Thus 1600 and 2000 are bissextile; 1700, 1800, and 1900, are common. But with the exceptions of the above even centuries, any year which exactly divides by four is leap year; and when there is any remainder, it indicates the number of years since leap year. The Gregorian computation was received in most foreign countries, ever since the reforming of the calendar; and by act of parliament, passed anno 1751, it commenced in all the dominions under the crown of Great Britain in the year-fol- lowing, ordering, that the natural day following the second of September, should be accounted the fourteenth; omitting the intermediate eleven days of the common calendar. BITTS, a frame composed of two strong pieces of timber, fixed perpendicularly in the fore part of a ship, whereon to fasten the cables as she rides at anchor; in ships of war, there are usually two pair of cable bitts, and when they are both used at once, the cable is said to be double bitted. There are Several other, smaller bitts; as, the topsail sheet bitts, paul bitts, carrick bitts, &c. - • BLACK, an epithet applied to anything opaque and porous, which imbibes the greater part of the light that falls on it, reflects little or none, and therefore exhibits no colour. - Bodies of a black colour are found more inflammable, be- cause the rays of light falling on them are not reflected out- wards, but enter the body, and are often reflected and refracted within it, till they are stifled and lost; and all other circum- stances being alike, they are also found lighter than white bodies, being more porous. - A Prussian chemist, (a Mr. Salverte,) in making experiments to improve printers’ ink, has discovered a process of producing from hempseed oil, a new species of black pigment, which, for brilliancy and intensity of colour, far exceeds any black known heretofore, and promises to render Prussian black as distin- guished a colour as Prussian blue is at present. The inventor has, we understand, not only applied it to improve printers’ ink, but also to other useful purposes, particularly as a superior and safe blacking for tanned leather. The inflammability of black bodies, and their disposition to acquire heat beyond those of other colours, are easily evinced. Some appeal to the experiment of a white and black glove, worn in the same sun; the consequence will be, a very sensibly greater degree of heat in the one hand than in the other. The same thing appears from the phenomena of burn- ing glasses, by which black bodies are always found to kindle soonest; thus a burning glass, too weak to have any visible effect upon white paper, will readily kindle the same paper when rubbed over with ink. Take a large tile, and having whited over one half of its superficies, and blacked the other, expose it to the sun; where having let it lie a convenient time, you will find, that whilst the whited part remains still cool, the black part has grown very hot. For farther satisfaction, leave on the surface of the tile a part retaining its native red, and exposing all to the sun, you will find the latter to have con- tracted a superior heat in comparison of the white part, but inferior to that of the black. So also on exposing two pieces of silk, one white and the other black, in the same window to the sun, the latter will be considerably heated, when the former has remained cool. Rooms hung with black are not only darker, but warmer than others. Cover the bulb of a thermo- meter with a black coating of Indian ink, and the mercury will rise several degrees. BLAGRAVE, Jo HN, an eminent mathematician, who flou- rished about the beginning of the seventeenth century. BLEACHING, an art which has been cultivated from time immemorial, is divided into two branches; the bleaching of vegetable, and of animal substances. These being of different natures, require different processes for whitening them. Vege- tables consist of oxygen, hydrogen, and carbon, of which the latter is in the greatest proportion; animal substances, besides these, contain a large quantity of azote, with phosphorus and sulphur. Hence, To Bleach Flar and Hemp, which, if examined, will be found to consist of a thin bark, enveloping a green sap, then the fibres or filaments that are used in the making of linen, and within that the woody part. The fibrous part only is used in the making of cloth, and is separated from the other substances, by being first steeped in soft water, until the putrefactive fer- mentation takes place, with the succulent part. and is taken out of the water as soon as the wood breaks easily between the hands, while it is yet green, and before the whole of its sap is separated. Well water, brackish water, and that which flows over gypseous soil, must be avoided, else the putrefaction will be accelerated, and the texture of the fibres injured. It is thus that a small quantity of salt accelerates animal putrefaction, while a great deal tends to prevent it; and the portion of saline substances held in solution in the water, hastens the corruption of the filaments, which it blackens and spoils. This operation of watering the flax, is tedious and noxious; it destroys the fish in any stream that may be used, and the smell of the putre- fying plants is offensive. Modern chemistry shortens this process, and performs it with less risk of injuring the flax, by the following process: If the stream of a solution of caustic alkali in water be introduced into a chamber about thirty feet square, in which the flax is suspended, it will produce the same effect as watering, in less time, with less expenses, and B L E B L E DICTIONARY OF MECHANICAL SCIENCE. 109 less danger to the flax, which is frequently injured by being too long steeped. Nothing remains after the watering is com- pleted, but the woody part, a hollow tube of compact flax. To separate these stalks, it must be kiln-dried to render it brittle, but too much heat must not be applied. It is next to be beaten or broken, either by manual labour with mallets on wooden anvils, as in the houses of correction, or by mills for the pur- pose. By this means the flax is divided into small fibres, and most of the wood reduced to small fragments, which are cleared away by scutching or threshing. Hackling, the last process, is nothing more than combing the flax in small parcels at a time through a pile of polished sharp iron spikes, placed pretty close together, in a wooden board ; the first hackle is coarse, the second finer, and the third finer again. The process of hackling divides the fibres of the flax from each other ; it detaches the minute fragments of wood which escaped the scutching, and it separates the tow from the short coarse flax. The flax is now ready to be spun into thread or yarn, which is afterwards manufactured into cloth. To Bleach Linen Cloth.-The linen, as it comes from the loom, is charged with the weaver's dressing, a paste of flour and water, to make it stretch more easily. To discharge this, the linen must be steeped 48 hours in water, till the extra- neous substance is decomposed by fermentation. Some bleachers boil the linen in water; but improperly, for paste is not soluble in boiling water. When the linen is well washed and rinsed, after the last process, it is of a grayish white colour, the fibres of which it is composed are naturally very white. And to separate matter that discolours the linen, is the busi- ness of bleaching. This gray substance is of a resinous nature, insoluble in water, and from its intimate union with the very fibres of the flax, it is difficult of separation, even by substances that have a solvent power. Alkaline leys, or solutions of alkali rendered caustic, have the property of dissolving resins, and are employed as men- strua for this purpose. Alone they are not sufficient to com- plete the process of bleaching. What appears a single fibre of flax in gray limen, is composed of a bundle of minute fila- ments, closely cemented by the resinous matter: therefore the potash first acts upon the resin of the external coating of the filaments; they are thus loosened or separated, and exposed to , the further action of the air. The second boiling of potash opens a second layer, and thus successively layer by layer, till the whole is opened to the centre. If the alkaline solution were sufficiently strong to force its way at once to the centre, it would act upon the filaments, and destroy the texture of the cloth. Each filament, after the alkaline process, retains an impregnation of colouring matter, so intimately united as to resist its further action. This can only be removed by the gradual influence of the atmosphere, according to the old method of bleaching, or by the modern improvement of using oxygenated muriatic acid. To explain the principle by which this latter part of the process is effected, we must con- sider that the resin, which forms the colouring matter of unbleached linen, is composed chiefly of carbon and hydrogen: this is partly dissolved by the alkaline ley, and what remains becomes united to the oxygen of the atmosphere, flying off in the state of carbonic acid gas, or remaining as water. The old manner of bleaching was tedious, two or three months being necessary to give the cloth its pure whiteness. The simplicity of the process, however, and the scanty apparatus it requires, recommends it to people who make their own cloth, particu- larly in Scotland and Ireland. The method of bleaching by the action of the atmospheric air is this:—After steeping the linen as mentioned above, to remove the weaver's dressing, the pieces of cloth are dried, and then submitted to the operation of bucking. For this pur- pose a ley is prepared, by dissolving a quantity of potash” in soft water, to which some soap is added. This liquor is heated to about 100 degrees, and poured upon the linen. After the * It is most economical to render it caustic for the purpose of bleaching. This is done by adding quicklime to the mild potash, the former having a stronger affinity for the carbonic acid than the latter. But care must be taken not to use the alkali too strong. acid, which is oxygenated by the oxyde of manganese. cloth is well down in the ley, it is drawn off, heated a little higher, and again poured upon the linen. This operation is repeated at successive intervals, allowing the ley to remain longer each time, moderately increasing the heat for about six hours. The cloth is then left steeping for about four hours, when it is taken out, rinsed, and carried to the fields, where it is spread upon the grass, and secured by pins; water is sprinkled on it to keep it moist' for some hours. After it has lain half a day, the watering is less frequent, and at night it is left to the dews. . On the succeeding days it is watered three or four times, if the weather be dry, and then it remains on the field till the air seems to have little effect in whitening. It is then brought back to the coppers, and bucked again with a ley somewhat stronger than the last, rinsed, and again spread in the field. It is thus alternately bucked and watered from ten to fifteen times, according to the state of the weather, making the bucking stronger and stronger, till about the middle, and then weaker and weaker till towards the conclusion of the operation. It must now be soured, or steeped, in some acid Iiquor. The acid which has been usually employed for souring, is formed by the fermentation of bran and water; sour whey has sometimes been used. But sulphuric acid very much diluted, has been found more convenient, and not more injuri- ous. The cloths are kept in the souring for about six days, if the liquor be formed of milk or bran, or a less time when sul- phuric acid is used. They are then rubbed with soap, parti- cularly the Selvages, as these resist most the action of the air. It is again bucked, rinsed, watered, and exposed to the atmo- sphere, and these processes are successively repeated, till the linen has acquired its proper degree of whiteness. To bleach by the oxygenated muriatic acid.—The oxygen- ated muriatic acid is only a combination of muriatic acid and oxygen. All vegetable colours are influenced by this acid, and whitened with more or less celerity; the colouring matter undergoes a real but slow combustion, which terminates by the formation of carbonic acid gas, that escapes into the atmo- sphere. In whatever manner the oxygenated muriatic acid is procured, the oxygen adheres to it very weakly, and upon this property depènds the possibility of producing speedily, in manu- factories, that action of bleaching which the atmosphere pro- duces slowly. The method of bleaching by oxygenated muriatic acid was quickly and successively introduced into the manu. factories of Manchester, Glasgow, Rouen, Valenciennes, and Courtray; and it has since been generally adopted in Great Britain, Ireland, France, and Germany. The advantages that result from this method, which accelerates the process of whiten- ing cottons, linens, paper, &c. to a really surprising degree, in every season of the year, can be justly appreciated by commer- cial people only, who experience its beneficial effects in many Ways, but particularly in the quick circulation of their capitals. To save the expense of first preparing the muriatic acid, you may mix with the oxyde of manganese, muriate of soda, or com- mon salt, and sulphuric acid diluted with water. The sulphuric acid acts upon the salt, and disengages from it the muriatic The proportions observed, when cotton is the article to be bleached, are, manganese, 30 parts; common salt, 80; sulphuric acid, 60; water, 120. For linen-cloth, the proportions are as follow: manganese, 60 parts; salt, 60; sulphuric acid, 50; water, 50. The better these substances are combined, the more easily M. the acid gas be disengaged by the action of the sulphuric a C101, - To ascertain the strength of the acid for bleaching, a solu- tion of indigo in the sulphuric acid is employed. The colour of this is destroyed by the oxygenated muriatic acid, and, according to the quantity of it that can be discoloured by a given quantity of the liquor, its strength is determined. Cloth is prepared for immersion in oxygenated water, by first soak- ing it in a ley of weak potash, and rinsing it afterwards in water, to free it completely from the weaver's dressing, and the saliva of the spinners. In this country, machinery is employed for rinsing and beating; the apparatus must be arranged according to the objects to be bleached; the skeins of thread suspended in the tub destined for them, and the cloth rolled upon reels in the aparatus. When every thing is thus diº the tubs are filled with oxygenated muriatic acid, by F - 110 B L E B L E JDICTIONARY OF MECHANICAL SCIENCE. introducing a funnel, which descends to the bottom of the tub, in order to prevent the dispersion of the gas. The cloth is wound, or the frame-work on which the skeins are suspended is turned several times, until, by taking out a small quantity of the liquor from time to time, and trying it by the test of the solution of indigo, it is judged that it is sufficiently exhausted. The weakened liquor is then drawn off, and may be again employed for another saturation. Experience proves that the use of the oxygenated muriatic acid alone weakened the cloth, and various methods of preventing its noxious effects upon the health of the workmen were tried, till it was discovered that an addition of alkali to the liquor destroyed its suffocating effects, without injuring its bleaching powers. The process began then to be carried on in open vessels, and has since been continued in this manner. The bleacher is now able to work his pieces in the liquor, and to expose every part of them to its action, without risk or inconvenience. Potash was at first used for this purpose; and although this advantage was unquestionably great, it was diminished by the heavy expense of the alkali, which was entirely lost. . It was afterwards discovered that the oxymuriatic acid might be com- bined with the alkaline earths, as lime and barytes, and also with magnesia, by this means forming oxymuriates, which were soluble in water, and had the property of bleaching. The oxymuriate of lime is at present used in almost all the bleach- ing grounds. If the oxygenated acid be passed through lime water, it combines with the lime, and forms oxymuriate of lime; but as the water can only retain a small portion of lime, to cause a larger quantity of lime to combine with the oxymu- riatic acid gas, the lime must be mechanically suspended in the water, into which the gas is made to pass, and agitated, so as to present fresh matter to the gas. By this means the oxymuriate of lime is dissolved in water, and used as a bleaching liquor preferable to the oxygenated muriatic acid and potash. At the great bleach-fields in Ireland, four leys of potash are applied alternately with four weeks’ exposure on the grass, two immersions in the oxygenated muriate of lime, a ley of potash between the two, and the exposure of a week on the grass, between each ley and the immersions. During summer, two leys, and fifteen days’ exposure, prepare cloth for the action of the oxygenated muriate; then three alter- nate leys, with immersions in the liquor, complete the bleach- ing, and nothing then will be necessary, but to wind the cloth through the sulphuric acid. The oxygenated muriatic acid gas may also be combined with lime in a dry state, or the water may be evaporated when it is employed for the formation of oxymuriates, which may then be very conveniently transported to any distance without injury to its detersive power. The sulphuret of lime, or the combination of sulphur and lime, which are both cheap articles, answer the purposes of potash in bleaching; it is useful in some cases, in others it will not supersede the use of alkali. To prepare the sulphuret of lime for the purpose of bleaching: Take sulphur of brim- stone, in fine powder, four pounds; lime, well slaked and sifted, twenty pounds; water, sixteen gallons; mix these well, and boil them for half an hour in an iron vessel, stirring them briskly. Soon after the agitation of boiling is over, the solu- tion of the sulphuret of lime clears, and may be drawn off free from the insoluble matter, which rests upon the bottom of the boiler. The liquor, in this state, is of the colour of small-beer, but not so transparent. Sixteen gallons of fresh water are afterwards poured upon the insoluble dregs in the boiler, to separate the remaining sulphuret from them. When it clears, it is drawn off, and mixed with the first liquor; to these again thirty-three gallons more of water may be added, which will reduce the liquor to a proper standard for steeping the cloth. Thus you have sixty gallons of liquor from four pounds of brimstone. When linen has been freed from the weaver’s dressing, in the manner already described, it is to be steeped in the solution of sulphuret of lime (prepared as we have described) for about twelve or eighteen hours, then it is to be taken out and well washed. When dry, it is to be steeped in the oxymuriate of lime for about fourteen hours, and then washed and dried. To whiten the linen, this process is to be repeated during six alternate immersions in each liquor. The rationale of these processes is the following: The oxy- genated liquor supplies to the cloth the place of the atmo- spheric air, and this in greater abundance, and in a state which renders its action on the cloth more expeditious and more complete. By the union of the oxygen with the carbon of the cloth, carbonic acid is formed, and flies off; and the cloth becomes white. - • To bleach by steam.—As the action of steam alone does not bleach, the concurrence of oxygen is necessary to aid the com- position of the carbonic acid; for this acid requires for its for- mation, 28 parts of carbon, saturated with 72 of oxygen; but all the oxygen in the apparatus would not be sufficient to saturate the colouring matter burnt by the alkaline combustion, and converted into carbon; this deficiency is supplied by immer- sion in any oxygenated liquor whatever, and the dispersion of the elastic fluid thus formed is then facilitated by expo- sure on the grass. To bleach cloth in this manner, it must be immersed in a slight alkaline caustic liquor, and placed in a chamber constructed over a boiler, into which is put the alka- line ley which is to be raised into steam. After the fire has been lighted, and the cloth exposed to the action of the steam for a sufficient time, it is taken out, and immersed in the oxy- genated muriate of lime, and afterwards exposed for two or three days on the grass. This operation, which is very expe- ditious, will be sufficient for cotton; but if linen cloth should still retain a yellow tint, a second alkaline caustic vapour bath, and two or three days on the grass, will be sufficient to give it the necessary degree of whiteness. For the use of private families, when the linen is dirtied by perspiration or grease, laundresses would do well to steep it for some time in clear water, made by mixing one quart of quicklime in ten gallons of water, letting the mixture stand twenty-four hours, and then using the clean water drawn from the lime. This whitens beautifully without injuring the cloth. The linen in many families is all washed in this manner. It is to be washed as usual, but will require much less soap to be used. To bleach Cotton, requires not the same preparations as hemp and flax. The first operation is scouring it in a slight alkaline solution, or by exposure to steam. It is afterwards put in a basket, and rinsed in running water. The immersion of cotton in an alkaline ley, how well soever it may be rinsed, always leaves with it an earthy deposit. Cotton bears the action of acids better than hemp or flax; and time is even necessary before their action can be prejudicial to it. Hence, by press- ing it down in a very weak solution of sulphuric acid, and afterwards renewing the acid by washing, lest, remaining too long in it, the cotton should be destroyed; all the earthy matter is removed from it. To bleach Wool.—Wool is a kind of hair, with which the bodies of some animals are covered, and is composed of filaments or tubes, filled with an oily or medullary substance. The sides of these tubes are perforated with a multitude of small pores, which communicate with a longitudinal tube. By chemical analysis, wool gives a great deal of oil, and carbonate of ammonia; caustic alkaline leys dissolve it entirely. It undergoes no change in boiling water; and scarcely alters when preserved in a place well aired; acids have very little action on it; and when exposed to a strong heat, it enters into fusion. The little action which acids have upon wool, and its unalterable- ness in water, even when aided by heat, render it necessary to have recourse to alkaline or saponaceous leys; but its solidity in these salts shews, that great prudence and caution must be employed in their use. In regard to acids, none have been hitherto used but sulphureous acid, obtained in the gaseous state by combustion. In the preliminary operations to which wool is subjected, a little of its grease is left, to secure it from insects. Wool is often freed from the grease by farmers, who wish to sell it at a high price; but in the subsequent manipulations, it is greased before it is combed and spun, and as this fat matter attracts dust, it dirties and thickens the stuffs. The first kind of bleaching wool receives, frees it from these impurities. This operation, called scouring, is generally performed by means of an ammoniacal ley, formed of five measures of river water and one of stale urine ; the wool is immersed for about twenty minutes in a bath of this mixture, heated to fifty-six degrees; it is then taken out, suffered to drain, and then rinsed in run- B. L. E B L E 111 .DICTIONARY OF MECHANICAL SCIENCE. ning water: this process softens the wool, and gives it the first degree of whiteness; it is thrice repeated, after which the wool may be employed. In some places, scouring is performed with water slightly impregnated with soap ; and indeed, for valuable articles, this is the preferable process, but it is expen- sive for articles of less value. Fulling the cloth adds still to the whiteness; and, if an increased degree be necessary, it may be procured by the action of the sulphureous acid; or of the fumes of sulphur in a state of combustion, or the vapour of that acid condensed and combined with water. Sulphuring is performed in an arched chamber, constructed in such a manner, that the articles exposed to the action of the sulphur can be suspended. The chamber being filled, a certain quantity of sulphur is placed in it in a state of combustion, in flat dishes, the entrance is shut, and all the interstices around the door stopped, to prevent the access of the atmospheric air. trates the stuffs, attacks and destroys the colouring matter, and effects the bleaching. The stuffs are left in the stoves from six to twenty-four hours afterwards. They are then taken out, and passed through a slight washing with soap, to remove the roughness they have acquired by the action of the acid, and to give them the necessary softness. But then this process is imperfect. At first, the acid of the sulphur acts only on the surfaces, and does not penetrate. This aerial immersion is not sufficient; the gas cannot introduce itself to a sufficient depth into the stuffs, and the superficies only is whitened. A superior method has been invented, which is, by making use of sulphureous acid; which is generated by the imperfect combustion of sulphur, and differs from the sulphuric acid, (oil of vitriol,) by containing less of the acidifying principle. It is the mean between sulphur and the sulphuric. Sulphureous acid gas unites easily with water, and in this combination is employed for bleaching wool or silk. The sulphureous acid in this liquid state, may be prepared by passing it through water in an apparatus nearly similar to that used for preparing oxy- genated muriatic acid. The cheapest method of obtaining it, is to decompose sulphuric acid by the mixture of some com- bustible capable of taking from it parts of its oxygen. In experimental chemistry, it is obtained by means of metallic substances with great purity, and particularly by mercury; but for bleaching, and where great economy is required, we would recommend the most common substances, and the following process. Take chopped straw, or saw-dust, and introduce it into a mattress; pour over it sulphuric acid, applying at the same time heat, and there will be disengaged sulphureous acid gas, (vapour of sulphur,) which may be combined with water in the apparatus. The pieces are rolled upon reels, and drawn through the sulphureous acid, by turning them, until the whiteness is sufficiently bright. They are then taken out, and drained on a bench covered with cloth, lest they should be stained by the decomposition of the wood and the sulphureous acid. They are next washed in river water, and Spanish white is employed, if necessary. This operation is performed by passing the pieces through a tub of clear water, in which eight pounds of Spanish white have been dissolved. To obtain a fine whiteness, the stuffs are twice sulphured. This process i. completed in one immersion, and a reeling of two or three OUll"S. To azure or blue the cloth, you throw, into the Spanish white liquor, a solution of one part of Prussian blue to 400 parts of water; shake the clothin the liquid, and reel it rapidly. Then, by a slight washing with soap, to give softness and pliability to the stuffs, the operation is terminated. The final operations of drying, stretching, pressing, &c. have all been illustrated in what has been said of dyeing and bleaching linen; for the directions vary so little in both, that it would be but a repeti- tion to detail here what the reader is already acquainted with. To bleach Silk.-Silk is a semi-transparent matter, spun by a caterpillar, and formed of a substance contained in its body, which becomes hard in the air. The filaments, prepared by the silk-worm, are rolled up in a ball, and in this state it is covered with a yellow varnish, that destroys its brilliancy, and renders it tough. By chemical analysis, silk gives carbo- nate of ammonia and oil; boiling water produces no effect upon it; alcohol makes it experience no change, but concem- trated alkaline leys attack and dissolve it. To give splendour to silk, it must be freed from its varnish. This covering is soluble in alkaline leys. Silk is usually scoured by soap, when it loses one-fourth of its weight. The matter disengaged has a fetid smell, and if the silk be not rinsed in plenty of water, putrid fermentation takes place. Even the least soap injures the whiteness of the silk. This is proved by the fact, that the splendour of the Chinese silks is brighter than that of the European ; and the Chinese employ no soap in their operations. A slightly alkaline ley will dissolve the varnish of the silk with- out using soap ; and this has also been effected by the action of boiling water at a very high temperature. The following method has been used very successfully in France. Take a very weak solution of caustic soda, and fill | with it the boiler of the apparatus for bleaching with steam. The acid, generated by the combustion of the sulphur, pene- Charge the frames with skeins of raw silk, place them in the apparatus until it is full ; then close the door, and make the solution boil. Having continued the ebullition for twelve hours, slacken the fire, and open the door of the apparatus. The heat of the steam, which is always above 250 degrees, will have freed the silk from the gum, and scoured it. Wash the skeins in warm water, wring them, place them again on the frame in the apparatus, and make the whole boil a second time. Wash them now several times in water, and immerse them in soapy water to give them softness. But the whiteness which silk acquires by these operations, is carried to a higher degree of splendour by exposing the material to the action of sulphureous acid gas, in a close chamber, or by immersing it in sulphureous acid, as we have explained for whitening wool. To bleach Prints, and printed Books.—The new mode of bleaching has been applied to the whitening of books and prints that have been soiled by smoke and time, and therefore it will be proper that we here explain this process. To whiten an engraving, immerse it in oxygenated muriatic acid, letting the article remain in it a longer or shorter space of time, according to the strength of the liquid. To whiten the paper of a bound book, all the leaves must be moistened by the acid, and there- fore care must be taken to open the book, and making the boards rest on the edge of the vessel, so that the paper alone shall be dipped in the liquid : the leaves must be separated from each other, to be equally moistened on both sides. In the same proportion as the liquor assumes a yellow tint, the paper becomes white. In about three hours, the book must be taken from the acid liquor, and the leaves plunged into pure Water, with the same care and precaution as recommended in regard to the acid liquor, so that the water touch only the two surfaces of each leaf. The water must be renewed every hour, to extract the remaining acid, and dissipate the unpleasant Smell. By this process, there is, however, some danger that the pages may not be all equally white, either because the leaves have not been sufficiently separated, or because the liquid has had more action on the exterior margins than those near the binding. The best way is to destroy the binding, and each leaf will thereby receive an equal and perfect immersion; this Second process is thus described by Chaptal. “They begin,” says he, “by unsewing the book, and sepa- rating it into leaves, which they place in cases formed in a leaden tub, with very thin slips of wood, or glass, so that the leaves, when laid flat, are separated from each other by inter- vals scarcely sensible. The acid is then poured in, making it fall on the sides of the tub, in order that the leaves may not be deranged by its motion. When the workman judges, by the whiteness of the paper, that it has been sufficiently acted upon by the acid, it is drawn off by a cock at the bottom of the tub, and its place is supplied by clear fresh water, which weakens and carries off the remains of the acid, as well as the strong smell. The leaves are then to be dried, and after being pressed, may be again bound up. “The leaves may be placed also vertically in the tub; and this position seems to possess some advantage, as they will be less liable to be torn. With this view I constructed a wooden frame, which I adjusted to the proper height, according to the size of the leaves which I wished to whiten. This frame sup- ported very thin slips of wood, leaving only the space of half a 112 B L O B L E DICTIONARY OF MECHANICAL SCIENCE. line between them. I placed two leaves in each of these intervals, and kept them fixed in their place by two small wooden wedges, which I pushed in between the slips. When the paper was whitened, I lifted up the frame with leaves, and plunged them to remove the remains of the acid, as well as the smell; this process I prefer to the other. “By this operation books are not only cleaned, but the paper acquires a degree of whiteness superior to what it possessed when first made. The use of this acid is attended also with the valuable advantage of destroying ink spots. This liquor has no action upon spots of oil or animal grease; but it has been long known that a weak solution of potash will effectually remove stains of that kind. “When I had to repair prints so torn that they exhibited only scraps pasted upon other paper, I was afraid of losing these fragments in the liquid, because the paste became dis- solved. In such cases I enclosed the prints in a cylindric glass vessel, which I inverted on the water in which I had put the mixture proper for extricating the oxygenated muriatic acid gas. This vapour, by filling the whole inside of the jar, acted upon the print; extracted the grease as well as ink spots; and the fragments remained pasted to the paper.” To prepare Oxygenated Muriatic Acid by an easy Method.— To oxygenate the muriatic acid, dilute it, and mix it in a very strong glass with manganese, so that the mixture may not occupy the whole contents of the glass. Air bubbles are formed on the surface of the liquor; the empty space becomes filled with a greenish vapour; and at the end of some hours the acid may be farther diluted with water, and then used. It will have an acid taste, because the whole has not been saturated with oxygen; but it will possess the qualities of the oxygena- ted muriatic acid. This process may be adopted when there is not time to set up an apparatus for distilling, to procure the oxygenated acid. To bleach Paper.—The oxygenated muriatic acid has also been applied to bleach paper, being more expeditious. If we were to bleach old printed papers, to be worked up again, we must boil them for an instant in a solution of soda, rendered caustic by potash. Then steep them in soap-water, and then wash them, after which the whole may be reduced to a pulp by the paper-mill. To bleach old written papers to be worked up again, we steep them in a cold solution of sulphuric acid in water, after which we wash them before they are taken to the mill. The acidulated water will be the more effectual if it be heated. To bleach printed papers without destroying the texture of the leaves, we steep the leaves in a caustic solution of soda, and afterwards in one of soap. Then we arrange the sheets alternately between cloths, just as paper-makers dispose their sheets of paper when delivered from the form. The leaves must then be put in a press, and they will become whiter, unless they have been stained with printers' ink or size. If one operation should not completely effect the whitening of the leaves, you must repeat the process till it is effectual. To bleach coloured rags to make white paper, we macerate the rags—then put them into a solution of caustic alkali, and next into the oxygenated muriatic acid;—lastly, they are to be steeped in diluted sulphuric acid.—These processes of bleaching have been classed under one general title, though the manufacture of paper has not been treated in conjunction with them. To remove Ink Stains.—Apply to the stain muriatic acid diluted in six times its weight in water, and after a minute or two wash it off; the application should be repeated as often as may be found necessary. The vegetable acids equally effectual are attended with less risk. A solution of the oxalic, citric, (acid of lemons,) or tartareous acids, in water, may be applied to the most delicate fabrics without danger or injury; and the same solutions will discharge writing, but not printing ink. They may be therefore employed in cleaning books defaced by writing on the margin. Lemon, and sorrel juice, will remove ink stains, though not so easily as the concrete acid of lemons or citric acid. To remove Iron Stains.—Ink stains, on the application of soap, are changed into iron stains. But the real iron stains are occasioned by the cloth coming in contact with iron, or its oxyde. Both may be removed by diluted muriatic acid, or by the acid of lemons. When suffered to remain long on cloth, they are taken out with difficulty, because the iron, by repeated moistening with water, and exposure to the air, acquires such an addition of oxygen, as renders it insoluble in acids; yet these spots may be discharged, by applying first a solution of an alkaline sulphuret, which must be well washed from the cloth, and afterwards a liquid acid. The sulphuret, in this case, extracts part of the oxygen from the iron, and renders it soluble in diluted acids. - To remove the stains of fruit and wine, prepare a watery solution of the oxygenated muriatic acid, or oxygenated muriate of potash or lime, to which a little sulphuric acid has been added. Steep the stained spot in one of these solutions till it is discharged; the solution can only be applied to white goods, for the uncombined oxygenated acid discharges printed and dyed colours. The oxygenate acid is easily applied by persons who have not the apparatus for Saturating water with the gas, thus:–Put a table-spoonful of muriatic acid (spirit of salt) into a teacup, and add to it about a tea-spoonful of pow- dered manganese; set this cup in a larger one filled with hot water; moisten the stained spot with water, expose it to the fumes which arise from the teacup, and if the exposure be continued a sufficient length of time, the stain will disappear entirely. To remove spots of grease from cloth, take a diluted solution of potash, which must be cautiously applied, to prevent injury to the cloth. Stains of white wax, from wax candles dropping upon the cloths, are removed by spirits of turpentine, or sulphu- ric ether, which will also take out the marks of white paint. To take spots of grease out of books, prints, or paper, warm the stained paper gently, and take out as much of the stain as possible by means of blotting paper; then dip a small brush in essential oil of turpentine, heated almost to boiling, (when cold, it acts weakly,) and draw it gently over both sides of the paper, which must be carefully kept warm. Repeat this operation as often as the spot imbibed by the paper, or its thickness, may render necessary. When the greasy substance has been removed, the paper may be restored to its former whiteness by the following method. Dip another brush in highly rectified spirit of wine, and draw it over the place which was stained, and particularly round the edges, to remove the border that would still present a stain. By employing these means with caution, the spot will disappear, and the paper will resume its original whiteness. Should the process be employed on a part written with common ink, or printed with printers’ ink, it will experience no alteration whatever. BLOCK MACHINERY. The machinery for manufacturing ship's blocks in the royal dockyard at Portsmouth, invented by Brunel, and adjusted in all its parts by the elaborate and ingenious calculations of Dr. Gregory, of the Royal Military Academy, Woolwich, who gives the following account of this apparatus, in vol. II. of his Mechanics, is greatly and de- servedly celebrated: The machines devoted to this purpose have been separated into four classes. 1. The sawing machine for converting the large timber into proper dimensions for the small machines to operate upon. 2. Those machines which are employed in form- ing the sheaves. 3. Those which form the iron pins for the blocks. 4. Those by which the shells of the blocks are manu- factured. They are all worked by means of two steam-engines, each of thirty-horse power. Either of these can be applied indifferently to work the chain pumps, or for turning the wood- mill; and their power is transmitted by a train of wheel-work, to a horizontal shaft, extending along the centre of the middle building, very near its roof. Upon this are a number of wheels and drums, which, by endless ropes and straps, communicate motion to the several subordinate machines. The order of the processes is this. The elm trees are first cut into short lengths, proper to form the various sizes ot blocks, by two large sawing machines, one a reciprocating, the other a circular saw. These lengths of the trees are next cut into squares, and ripped or split up into proper sizes by four sawing benches with circular saws, and one very large recipro- cating saw, which is employed for cutting up the pieces for very large blocks. - - B L O B L O DictionARY OF MECHANICAL SCIENCE. 113 The scantlings, thus prepared for the blocks, are perforated in three boring machines, with a hole through each to contain the centre pin for the sheaves of the block, and as many other holes in a direction perpendicular to the former, as the number of sheaves it is to have ; these holes being intended as the com- mencement of the several mortises to contain the sheaves. The blocks are next mortised in three mortising engines, which elongate the holes abovementioned to their proper dimensions. Here the motion of the sliding frame for the chisels, is communicated to it by means of a long working beam or lever, extending the whole length of the frame at the top of it. At one end it is united by a connecting rod with the chisel frame; and at the other it is fixed to an axis, which is supported by the framing, and which forms its centre of motion. A connecting rod is joined to it in the middle of the beam ; the lower end of which is worked by a crank, formed in the middle of the main axis, which is situated in a direction perpendicular to that which we have described, and is supported in the fram- ing. It is provided with a cone for casting off the movement. The engine with the beam acts with surprising rapidity, mak- ing upwards of 400 strokes per minute, at every one of which it cuts out a chip from each mortise as thick as pasteboard. Its movement is, indeed, so rapid, that the chisels cannot be distinctly seen when it is at work; so that the mortises seem to lengthen, and chips to fall out, without any evident cause: The angles of the blocks are next cut off by three circular saws, as preparatory to reducing them to the elliptical figure. The outside surfaces of the block are then formed to their true figure by three shaping-engines, each of which forms every part of ten blocks simultaneously. The scores, or grooves, round the block are next formed, to receive the rope or strap by which they are suspended; this is effected by two scoring- engines. Then the blocks are trimmed by manual labour, to smooth and polish them. In order to make the sheaves, the first process is cutting pieces or flakes off the end of the trees of lignum vitae, of a suitable thickness to form the sheaves. This is accomplished by a reciprocating and two circular saws. These flakes are made circular, and the centres pierced in two rounding and centering machines, or trepan saw. A hole is next excavated in the centre of each sheave, to inlay the coak or piece of bell metal, which is fitted into the centre of each sheave, to form a socket for the centre pin. The centre holes through the coaks are next broached out to a true cylinder in three broaching-machines. The last process is turning the faces and edges of the sheaves to a flat surface, in three facing lathes, which also form the grooves round the edges for them, for the rope which encom- passes them when in the block. There are also two machines for making dead eyes, which are both ingenious and complete. The whole number of machines is thirty-seven. BLocks are used for various purposes in a ship, either to increase the mechanical power of the rope, or to arrange the ends of them in certain places on the deck, and they may be readily found when wanted; they are consequently of various sizes and power, and obtain various names, according to their form or situation, thus: . . - A Single Block, contains only one sheave or wheel. A Double Block, has two sheaves. A Long Tackle Block, has two sheaves, one below the other. A Snatch Block, is a single block with an opening on one side, in which the bite of a rope may be laid instead of reeving the end through, which, in some circum- stances, would be very inconvenient. The Spring Block, an invention of Hopkinson, of Philadelphia, calculated to assist a vessel in sailing, and particularly intended by him to be ap- plied to the sheets and the dead-eyes; it is composed of a common block or dead-eye, attached to a spiral spring of well tempered steel, within the cavity of which is a chain of suitable strength, called a check-chain; when the spring is not in action, this chain is slack; but, when the Spring is extended by the force of the wind as far as it may be without injury, the check-chain begins to bear, and prevents its farther extension. Top Bloch, is a large single block with an iron strop and hook, by which it is hung to an eye-bolt in the cap, and is used to sway up or lower down the topmasts. or threefold blocks, applied to hoist or lower the main and fore 13. Jear Blocks, are twofold Wiol Block or Voyal Block, is a large block through yards. which the voyal or messenger passes when the anchor is weighed by the fore or jear capstan. Clue-garnet and Clue- line Blocks, are distinguished from others by having shoulders upon their upper parts, through which the strop is laid, and is applied to draw up the clues or lower corners of the square sails to their respective yards. Cat Block, is a two or three fold block, with an iron strop and large hook to 'it, and is employed to draw the anchor up to the cathead. - • Every block is composed of three, and generally four, parts: 1. The shell, or outside wooden part. 2. The sheave, or wheel, on which the rope runs. 3. The pin, or axle, on which the sheave turns. 4. The strop, or part by which the block is made fast to any particular station, and is usually made either of rope or of iron. Iron-stropped Blocks, frequently have the hook working in a swivel in order to turn it, that the several parts of the rope of which the tackle is composed, may not be twisted round each other, which would greatly diminish the mechanical power. . . Block and Block, is the situation of a tackle when the blocks are drawn close together, so that the mechanical power becomes destroyed till the tackle is again overhauled by draw- ing the blocks asunder. , - } BLONDEL, FRANcis, a celebrated French mathematician and military engineer, was born in Picardy in 1617, and died in Paris in 1686. He was author of two distinct works on architecture, and another on fortification ; besides which, he published “A Course of Mathematics,” “The Art of throwing Bombs,” and several ingenious pieces in the Memoires of the French Academy of Sciences, particularly in the year 1666. BLOOD, Circulation of the. About the year 1600 Mr. Har- vey, an English physician, discovered the process (if we may so call it) of the circulation of the blood ; to form a distinct notion of which, it will be necessary to describe the structure of the arteries, veins, and nerves; and principally the cavities of the heart, by means of which the blood is propelled through the body. To these we now proceed :- The arteries are blood-vessels consisting of a close texture of strong elastic fibres, woven in various webs, laid in different directions, and interspersed with an infinity of delicate nerves, veins, and minuter arteries. They are divided and subdivided into numberless branches and ramifications, that become smaller and smaller as they recede from the heart, until at last their extremities are found much more slender than the hairs of our heads, (and are therefore called capillary arteries,) which either unite in continued pipes with the beginnings of the veins, or terminate in small receptacles, from which the veins derive their origin. The arteries have no valves, but only have their trunks spring from the heart: they throb and beat perpetually whilst life remains; their extremities differing in the thickness of their coats and some other particulars, according to the nature of the part which they pervade. All the arteries in the lungs (except the small ones that convey nourishment to them) are derived from the great pulmonary artery, which issues from the right ventricle of the heart. And all the arteries in the rest of the body proceed from the aorta, (which obtained this name, because the ancients thought it contained air only,) whose trunk springs from the left ventricle of the heart. The veins resemble the arteries in their figure and distribu- tion; but their cavities are larger, and their branches, perhaps, more numerous. Their coats are much weaker and more slender than those of the arteries. They are furnished with several valves, contrived in such a manner as to permit the blood to pass freely from the smaller into the larger branches, but to stop its retrogression. They neither throb nor beat. Their beginnings form continued pipes with the extremities of the arteries, or arise from some gland or receptacle where the arteries terminate. All the veins in the lungs, from their capillary beginnings growing still larger, unite at last, and dis- charge their blood into the left auricle of the heart: and all those in the rest of the body empty themselves in like manner #. the vena cava, which opens into the right auricle of the eart. The nerves deduce their origin from the brain, or its appen- dages, in several pairs, of a cylindric form, (like so many skeins of thread with their respective sheaths,) which in their progress 2 G 114 , B L O JB L () , DICTIONARY OF MECHANICAL SCIENCE. decrease by endless divisions, and subdivisions, until at last they spread themselves into a texture of filaments so slender, and so closely interwoven with each other over the whole body, that the point of a needle can hardly be put upon any part of - tº tº * ... * - º © | the larger arteries, which constantly communicate with corre- it, without touching the delicate branch of some nerve. It has been found by many trials, that when an artery is laid bare, and a ligature made upon it, if it be opened with a lancet between the ligature and the heart, the blood will rush out with great violence ; and a rapid, jerking stream will con- | tinue, (if it be not stopped by art,) until, through loss of blood, But if the same artery be opened the animal faints or dies. between the ligature and extremities, a few drops only will ooze out from the wounded coats. On the other hand, when a yein is laid bare, and a ligature made upon it, if it be opened between the ligature and the extremities, the blood will gush But if the same vein out, as we see in common venesection. e be opened between the binding and the heart, no blood will appear. From these experiments it is obvious to the slightest attention, that the blood flows from the heart, through the arteries, to the extreme parts of the body; and returns again: through the veins to the heart. For the regular performance and continuation of this motion of the blood through all the different parts of the body, the heart, which is the primum mobile, giving the first impulse, is furnished with four distinct muscular cavities, that is, with an auricle and a ventricle on the right side, and an auricle and ventricle on the left. order:—it is received from the veins, first into the right auri. cle, which, contracting itself, pushes the blood into the right ventricle, at that instant dilated. The moment this ventricle is filled, it contracts itself with great force, and impels the blood into the pulmonary artery, which, passing through the lungs, and returning by the pulmonary veins, is received into the left auricle of the heart, and from thence it is pushed into the left *Wentricle; which, being thus filled, contracts itself, and drives, the blood with great rapidity to all the parts of the body, and from them it returns again through the veins into the right auricle of the heart, as before. It is very remarkable, that we have here a double circulation: one from the right ventricle, through the lungs, to the left auricle of the heart, in order to convert the chyle into blood, and finally prepare it for the nourishment of the animal; the other, from the left ventricle, through the whole body, to the right auricle of the heart, which serves to apply that nourishment to every part, besides various other purposes. - But to proceed —Of these four muscular cavities, the two auricles are contracted at the same instant, while the two ven- tricles are dilated; the ventricles, in their turn, are contract- ing themselves at the same instant that the auricles are dilat- ing. The arteries, in like manner, beat in alternate time with the ventricles of the heart. The nerves, as well as the veins and arteries, act their part in this rotation of the blood; for if the eighth pair of nerves which proceeds from the brain to the heart be bound up, the motion of the heart immediately languishes, and soon ceases entirely. Thus we have a species of perpetual motion, which none but a Being of infinite wisdom and power could produce ; yet whose continuation requires the constant aid of the same hand that first gave it existence. spirits to the heart, to give it a vigorous contraction. The heart, at the same time, pushes the blood into the brain, to Supply it with new spirits; by which means the head and the heart give continual mutual support to each other. But this is not all; the action of the heart sends the blood and other Yital humours over the whole body by the arteries, and distri- butes nourishment and vigour to every part, (while perhaps the animal spirits, from the extremities of the nerves, return again into the blood,) and the whole refluent mass is conveyed back through the veins into the heart, which enables it, without intermission, to persist in rolling this tide of life. - But here it must not be supposed, that the arteries pass on tº the extremities of the limbs, before they communicate with the returning veins; tation has been the stump by Through these cavities, curiously adapted. to their respective offices, the blood cirdulates in the following The brain transmits animal. for upon this supposition, after an ampu- performed, whatever blood might be brought to the arteries, it is certain, none of it could be i l carried back again to the heart; because: the intercourse between the heart and the limbs would, in this case; be entirely cut off. But the all-wise Author of our being, has provided for this exigency, by forming a great number of less branches from sponding branches of the returning veins. And hence, it is easy to conceive how the circulation is carried on after ampu- tation has been performed. & Cº. - . BLOWPIPE, Alcohol.-1. Copper ball, containing alcohol. 2. Tube to convey alcohol to, 3, A lamp, which keeps, it boil- ing. 4. Jet of alcohol inflamed by the lamp. , 5. Glass tube, bent by the flame. - This is really an useful instrument. The alcohol in the cop- per ball is boiled by the flame of the lamp placed underneath; this causes expansion, and the escape of the gas in a jet passing through the flame; and from its highly inflammable nature, a stream of intense heat is thus made to play upon any substance you wish to bring into fusion. There are many different kinds of blowpipes; but none more powerful than the Oxy-hydrogen blowpipe of Mr. Gurney. - A flux for the blowpipe, that will cause the particle of mineral, under examination, to run into a metallic globule upon the charcoal, as soon as any other now in use, may be thus made :-Take of borax 1 ounce, nitre 2 drachms, pounded flint glass 2 drachms, and calcined horse's hoof half an ounce; these are all to be fused together in a crucible, taking care to add the horse’s hoof last, and stirring it well in with an iron spatula; when it is quite fluid, pour it into cold water, which will render it brittle, and thereby it may be easily pulverized. It is to be kept in well-closed phials, free from moisture, and the expense will be very trifling, compared with its great importance. Hydrogen gas mixed with oxygen, furnishes an explosive compound of prodigious force. These gases, mixed in a blad- der, in the exact proportion to form water, and afterwards condensed, and allówed to issue by a jet, which may be in- flamed, and used in the operations of the blowpipe, under the title of Oxy-hydrogen Gas Blowpipe, of which the following figure represents Mr. Gurney’s instrument, - B. L. O. 3 O A. 115 BIGTIONARY OF MECHANICAL SCIENCE. Mr. Gurney has proved, by experiment, that the flame.from ; the stop-cock. - A, silk tube is attached to the end of the tube a mixture of oxygen, and, hydrogen gases will pass through successive layers of the smallest, wire gauze;—through the smallest apertures made in lead;—through plaster of Paris; pipe clay; the natural pores of cane; and those of Hondu- ras mahogany. He has shewn, that no means have hitherto been adopted, capable of preventing the explosion of these “mixed gases under certain circumstances; and has thus shewn the great danger attending the use of instruments. One of the principal advantages attending the well, constructed blowpipe before us, consists, it is said, in its being perfectly safe; and every apprehension of danger being thus removed from the mind of the operator, he is enabled to give his undi- vided attention to the changes and effects taking place in the substance operated upon; and whilst coolly examining, and noting every circumstance, a slight pressure with one hand is all that is requisite to produce a degree of heat of any required intensity. In this machine, A is the safety chamber, B, a water trough, through which the gas is made to pass from the gaso- meter D, by the stop-cock C, through a tube which reaches to the bottom of the water trough; E is a cork, fitted into the neck of the same, from which it is thrown out, should an explosion take place on the surface of the water; F is a gauge, to indicate the necessary height of the column of water in the trough; G is a transferring bladder, which is made to screw and unscrew to and from the stop-cock H, and for supplying the gasometer with the gases, which may be charged and re- charged at pleasure by an assistant during its action, so as to , keep up the most intense flame, for any length of time. . A valve is placed between the gasometer and the transferring bladder, which prevents the return of the gas; I, I is the light wooden, or stiff pasteboard cap, which combines sufficient strength, with great lightness, so that in case an explosion of the gasometer should happen, it is merely thrown a short height into the air, by the force rupturing the strings which connect the cap to the press board. To these strings are attached small wires, which pass through the table of the instrument, as at Linto the press board below, where they are secured ; this press board is kept in an horizontal position by the stand, so that when the requisite pressure is given to it, the cap I, I is brought to bear equally on the gasometer D. . The gasometer bladder, (or silk bag,) is tied to a piece of bladder, which screws into a long tube, laid into and across the table, which permits it to be unscrewed at pleasure from the body of the instrument, and immersed in warm water, when it requires softening; affording also the means of fixing on another bladder, if any accident renders it necessary. The stop-cock of the charging bladder G is fixed at one end of the tube, just described, and the stop-cock of the water trough on the other. To operate with the instrument, pressure by the hand is applied to the press board, which draws down the cap I, I on the gasometer D, and forces the gas which it contains through the stop-cock C, through the water tube and safety chamber A, to the jet at the end, where it is burned. When the pressure on the press board is too slight, or when the hand is taken off, the flame returns into the safety chamber, and is extinguished. When it is required to suspend the operation, the hand need only be taken off from the pressing board, the water in the trough acts as a self-acting valve, in preventing the escape of the gas from the instrument, and saves the necessity of turning. before described in the water trough, which prevents the splashing of the water, sometimes: occasioned by unskilful management. : * * , - The ease and confidence with which this instrument may be used, and its wonderful power in reducing, almost instan- taneously, the hardest, and most refractory substances, will enable the chemist, the philosopher, and the artisan, to avail themselves of the astonishing powers of an oxy-hydrogen blow- pipe, not only without any personal risk, but even without the apprehension of any. Gun flints are instantly fused by this instrument, and formed into a transparent glass; (but owing to the rapid expansion of the water of crystallization, which causes the flints to break and fly off in pieces, it is recommended that they be first deprived of it by calcination.) China melts into a perfect crystal. All kinds of porcelain are readily fused; previously assuming a beautiful white vitrified appearance. Rock crystal is quickly melted, giving out a beautiful light. Emerald, sapphire, topaz, beryl, and all the other precious stones, melt before it into transparent glassy substances. Ba- rytes, strontia, lime, allumina, exhibit very striking and beautiful phenomena. Magnesia fuses into hard granular particles, that will scratch glass. The metals (even platina) are all quickly fused by it. A steel, file, brought into contact with the flame, fuses and scintillates in the most beautiful manner, forming a magnificent firework. In a word, all descriptions of stones, slates, and minerals, are melted, sublimed, or volatilized, by its all-subduing power. * BLow ING of Glass. See GLAss. BLoWiNG Machines. See FURNAce. BLUE, one of the seven primitive colours of the rays of light, into which they are divided when refracted through a glass prism. See Colours and PR1s M. The blue colour of the sky is a remarkable phenomenon, which has been variously accounted for by different philosophers. La Hire, after Leo- nardo de Vinci, attributed it to the effect which is produced by viewing a dark body through a white transparent one, which he observes always gives the sensation of blueness; and thus the sky being itself totally devoid of light, when viewed through the air illuminated and whitened by the sun, appears of that blue colour so constantly observed. According to Newton, however, the phenomenon is to be accounted for on other principles. He observes, that all the vapours, when they begin to condense and coalesce into natural particles, become first of such a bigness as to reflect the azure rays, before they can constitute clouds of other colours. Bouguer ascribes this blueness of the sky to the constitution of the air itself, being of such a nature that the fainter coloured rays are incapable of making their way through any very considerable portion of it. We conceive, that this blue colour is occasioned by the vapours mixed with air, and which have the property of reflecting the blue rays more copiously than any others. BOATS, small open vessels, conducted on the water by rowing or sailing, are distinguished by different names, accord- ing to their size and construction. The long boat, usually the largest boat that accompanies a ship, is generally furnished with a mast and sails, and may be armed and equipped for cruising short distances; her principal employ, however, is, to bring heavy stores or provisions on board, and also to go up small rivers to fetch water, wood, &c. The launch, a boat which has greatly superseded the use of the long boat, particu- larly by merchant ships in . the Mediterranean, is longer, more flat-bottomed, and by rowing a greater number of oars, is better adapted for going into narrow, and shallow rivers. The barge, a long, narrow, and light boat, employed to carry the principal officers, as admirals and captains of ships of war, and is very unfit for sea. A pinnace resembles a barge, but is smaller, never rowing more than eight oars, whereas a barge never rows less than ten ; the pinnace is for the accommoda- tion of the lieutenants, &c. The cutters of a ship are broader, deeper, and shorter than the barge or pinnace, are fitter for sailing, and commonly employed in carrying light stores, pas- sengers, &c. to and from the ships; they are built differently from the former boats; the lower edge of every plank overlay- ing the upper edge of the piank below it, which is called clinch work. They generally row six oars; sometimes only four, 116 B O IO B O O DICTIONARY, OF MECHANICAL SCIENCE. which last is termed a jolly boat. Yawls resemble pinnaces, but are generally rowed with six oars. A wherry is a sharp light boat, used in rivers or harbours. The wherries allowed to ply about London, are either scullers wrought by a single person with two oars, or oars wrought by two persons, with each an oar. A Moses is a flat-bottomed boat used in the West Indies, for bringing off hogsheads of sugar, and is termed single or double, according to its size. A punt is a sort of oblong flat- bottomed boat, nearly resembling a floating stage. A felucca is a large and strong passage-boat, used in the Mediterranean, having from ten to sixteen banks of oars. BOAT-HOOK, an iron hook with a sharp point on the hin- der part thereof; it is fixed upon a long pole, by the help of which a boat is either pulled to, or pushed off from, any place. BOB of a Pendulum, or BALL of a Pendulum, is the metallic weight which is attached to the lower extremity of a pendulum rod, by means of a tapped adjusting nut, at such a distance from the point of suspension as the time of a given vibration requires. See PENDULUM. - BODY, or Solid, in Geometry, is that which has three dimensions, viz. length, breadth, and thickness. BoDY, in Physics of Natural Philosophy, is a solid, ex- tended, palpable substance; of itself merely passive, and indifferent either to motion or rest; but capable of any sort of motion, and all figures and forms. Body is composed, accord- ing to the Peripatetics, of matter, form, and privation ; accord- ing to the Epicureans and Corpuscularians, of an assemblage of hooked heavy atoms ; according to the Cartesians, of a cer– tain quantity of eatension ; and according to the Newtonians, of a system of association of solid, massy, hard, impenetrable, moveable particles, ranged or disposed in different manners, whence result bodies of different forms, which receive particu- lar denominations, according to the circumstances under which they appear. These elementary or component particles of bodies must be infinitely hard, so as ever to remain unbroken and unchanged; which, as Newton observes, is necessary, in order to the world’s remaining in the same state, and bodies continuing of the same nature and texture in several ages. Bodies are either hard, soft, or elastic. A hard Body is that whose parts do not yield to any stroke or percussion, but retäins its figure unaltered. A soft Body is that whose parts yield to any stroke or impression, without restoring themselves again. An elastic Body is that whose parts yield to any stroke, but immediately restore themselves again, and the body retains the same figure as at first. We know not, however, of any bodies that are perfectly hard, soft, or elastic ; but all possess these properties in a greater or less degree. BoDies are also either solid or fluid. . A solid Body is that in which the attractive power of the particles of which it is com- posed exceed their repulsive power, and, consequently, they are not readily moved one among another, and therefore the body will retain any figure that is given to it. A fluid Body is that in which the attractive and repulsive powers of the parti- cles are in exact equilibrio, and therefore yields to the slightest impression. See Solid and FI.UID. Regular Bodies, or Platonic Bodies, are those which have all their sides, angles, and planes, similar and equal, of which there are only the five following, viz. 1. Tetraedron, contained under 4 equilateral triangles. 2. Hexacdron, . . . . . . tº º e º e º º 6 squares. 3. Octaedron, .............. 8 triangles. 4. Dodecaedron, ... . . . . . . . . . 12 pentagons. 5. Icosaedron, . . . . . . . . . . . . . 20 triangles. For the method of forming the five regular bodies, as also for finding out the surfaces and solidities, see the respective articles. BOILING. See EBULLITION. BOMB, a large shell of cast iron,' having a great vent to receive the fusee, which is made of wood. Bombs are of different magnitudes, and are filled with gunpowder and other combustibles. When shot from the mortar, the fusee in them takes fire, and its length is so adjusted, that by the time the shell has finished its flight, the fusee has burnt up, and ex- plodes the gunpowder within so as to burst the shell to pieces just as it is falling to the ground ; this, of course, increases its execution, and causes greater devastation. A grenade re- sembles a bomb, but is less, and may be cast with the hand, The usual weight of a grenade is three pounds; and filled with a strong powder lighted by a fusee. BOOKBINDING... The leaves being accurately folded, are beaten with a hammer on a stone, to make them smooth, and lie close ; they are then put into a press, and sewed on boards, after which the backs are glued, and the bands opened and scraped to fix the pasteboard covers; the back is rounded with a hammer, and the book is fixed in a press, between two boards. Holes are then made for fixing the pasteboards to the volume, which is pressed a third time. It is then put to the cut- ting-press, between two boards, one lying even with the press for the knife to run upon, the other above for the knife to run against; after this operation, the pasteboards are squared; the leaves sprinkled, by dipping a brush in vermilion and sap green, holding it in one hand, and spreading the hair with the other. The leather covers are moistened, cut to the size of the book, smeared with paste, and afterwards stretched over the paste- board on the outside, and doubled within, after having taken off the four angles, and indented and platted the cover at the head-band. The book is now covered and bound between two bands, and set to dry. It is afterwards washed with paste and water, and then sprinkled with a brush ; if marbling be required on the leathern covers, the spots are made by the addition of vitriol. The book is glazed with the white of an egg, and polished with a hot iron; the letters and ornaments are made with gilding tools, or brass cylinders, rolled along by a handle. To apply the gold, the leather is glazed with whites of eggs diluted with water, when nearly dry the gold leaf is laid on, and the letters, or ornaments, are made with tools heated in a charcoal fire. For preserving books from the depre- dations of worms, mineral salts, alum, and vitriol should be mixed with the paste used by bookbinders; and instead of flower, the paste should be made of starch. A little pulverized alum is useful, if strewed between the book and its cover, and upon the shelves of the library. A few drops of any perfumed oil will secure libraries from the consuming effects of moułdi- ness and damp. Russian leather, which is perfumed with the tar of the birch-tree, never moulders; and merchants suffer large bales of this article to lie in the London docks in the most careless manner, knowing that it cannot sustain any injury from damp. BOOM, in Marine Fortification, a strong iron chain, fastened to a number of spars, and extending athwart the mouth of a harbour or river, to prevent the enemy’s vessels from entering, but may be occasionally sunk or removed. . Boo M, a long pole run out from different places in the ship, to extend the bottoms of particular sails, as jib-boom, flying jib-boom, studding-sail booms, driver or spanker-boom, ring- tail boom, main-boom, square-sail boom, &c. Fire Booms, strong poles occasionally thrust out from a ship's side, &c. to prevent the approach of fireships, firestages, or vessels accidentally on fire. Boo MING, among Sailors, denotes the application of a boom to the sails. Booming of the sails is never used but in quarter winds, or before a wind. When a ship is said to come booming towards us, it signifies that she comes with all the sail she can make. BOOTES and Mons Me NALUs, a Constellation in the northern hemisphere. Grecian fable makes Böotes to be Arcas, a son of Jupiter and Calisto. Juno, who was jealous of Jupiter, changed Calisto into a bear; and she was near being killed by her son Arcas in hunting. Jupiter, to prevent further mischief from huntsmen, made Calisto the constellation Ursa Major, and on the death of Arcas, transferred him to heaven, with the title and office of Bear Guard. The splendid star Arcturus, is frequently mentioned in holy writ, particularly in the book of Job. This star is placed near Virgo, in a line with Spica, on the meridian of the Ecliptic. The ancient Greeks called this constellation Lycaon. The Hebrews call it “the Barking Dog. The Latins, among other names, called Böotes Canis. Going back to the time when Taurus opened the year, and when Virgo was the fifth of the zodiacal signs, we shall find the brilliant star Arcturus, so remarkable for its red *and fiery appearance, corresponding with a period of the year B O R B O S ‘DICTIONARY OF MECHANICAL SCIENCE. 117 as remarkable for its heat. Pythagoras, who introduced the true system of the universe into Greece, received it from Óenuphis, a priest of On, in Egypt. And this college of the priesthood was the noblest of the East, in cultivating the studies of philosophy and astronomy. Among the high honours which Pharaoh conferred on Joseph, he very wisely gave him in mar- riage “a daughter of the priest of On.” Joseph is said to have died 1635 years before Christ. The supposed era of the history of the book of Job is fixed 1513 years before Christ. These facts are 900 years prior to the age of Pythagoras. And it is 4000 years since the bull ceased to be the leader of the celestial host. The Greeks cannot then claim the invention of the con- stellation Böotes. • * Boundaries and Contents of this Constellation:—North by Draco, east by Corona Borealis and Serpens, south by Virgo, and west by Canes Venaticiand Coma Bernices. Böotes con- tains 54 stars, namely, one of the 1st magnitude, six of the 3d, eleven of the 4th, &c. Arcturus, the largest star in this con- stellation, having 211° 54' 16" right ascension, and 20° 8' 0" N. declination, rises and culminates, at London, as in the following table: Meridian Altitude, 58° 37'. MONTH. RISES. CULM. MONTH. RISES. CULM. ho. mi. ho. mi. ho. mi. ho. mi. Jan. 11 30 A. | 7 15 M. July 11 26 M. 7 35 A. Feb. 9 16 A. | 5 5 M. Aug. 9 22 M. 5 30 A. Mar. 7 30 A. | 3 15 M. Sept. 7 18 M. 3 33 A. April 5 35 A 1 26 M. Oct. 5 18 M. 1 41 A. May 3 45 A. | 11 35 A. Nov. 3 15 M. l l 45 A.I. June 1 35 A 9 30 A. Dec. L 14 M. 9 30 M. Arcturus rises on the north-east by east point of the com- pass; and from the circumstance of its variation being greater, in consequence of a proper motion of its own, it is supposed to be the nearest star to the earth of any in the northern hemisphere. BOOT-TOPPING, the operation of scraping off the grass, slime, shells, &c. which adhere to the bottom of a ship, near the surface of the water, and daubing it over with a mixture of tallow, sulphur, and rosin. Boot-topping is chiefly per- formed where there is no dock. - BORAX, in Chemistry, a salt in appearance somewhat like crystals of alum, brought originally from the East Indies in an impure state, and afterwards freed from its impurities by cer- tain processes in the European , countries. It was long a matter of uncertainty, whether this salt be a natural or facti- tious substance in those countries from whence it is brought; but it is now beyond a doubt, that it is naturally produced in the mountains of Thibet, from whence other parts of the eastern continent are supplied. It is produced in the kingdom of Jum- late, about thirty days’ journey north from Betowle, a small principality about 200 miles north-east of Lucknow. The place where it is found is said to be a small valley surrounded with snowy mountains, in which is a lake about six miles in circumference ; the water of which is constantly so hot that the hand cannot bear it for any time. Around this lake the ground is perfectly barren, not producing even a blade of grass; and the earth is so full of a saline matter, that after falls of rain or snow it concretes in white flakes on the surface, like the matron of Hindostan. On the banks of this lake, in the winter season, when the falls of snow begin, the earth is formed into small reservoirs six inches high ; when these are filled with snow, the hot water from the lake is thrown upon it; which, together with the water from the melted snow, remains in the reservoir, to be partly absorbed by the earth, and partly evaporated by the sun; after which, there remains at the bottom a cake of sometimes half an inch thick of crude borax, which is taken up and reserved for use. It can only be made in the winter season, because the falls of snow are indispensably requisite, and also because the saline appearances upon the earth are strongest at that time. When once it has been made on any spot, it cannot be made again on the same spot till the snow has fallen and dissolved three or four times, when the saline efflorescence appears as before. BORING, in a general sense, the art of perforating, or making a hole through any solid body. . Boring of waterpipes is as follows:—The poles of alder, which is a very useful wood in making pumps, waterpipes, &c. being laid on horses or trestles of a foot height, to rest the auger upon while they are boring, they set up a lathe to turn the least end of the poles, to fit them to the cavities of the great end of the others. They turn the small ends of the poles about five or six inches in length, to the size they intend to bore the bigger ends about the same depth, viz. five or six inches. This is designed to make a joint to shut each pair of poles together, the concave part being the female part, and the other the male of the joint. In turning the male part, they turn the channel in it, or a small groove at a certain distance from the end; and in the female part they bore a small hole to fit over this channel. This being done, they bore the poles through ; and to prevent them from boring out at the side, they stick great nails at each end to be a guide in boring. It is usual, however, to bore them at both ends; so that a crooked pole can be bored through and not spoil it. Bori Ng, in Farriery, a cruel and absurd method of treating a wrenched shoulder. - Bori Ng, in Mineralogy, a method of piercing the earth with scooping irons, which being drawn back at proper times, bring up with them samples of the different strata through which they have passed; by the examination of which, the skilful mineralogist will be able to guess whereabouts a vein of ore, or a stratum of coal, may lie ; or whether it will be worth while to open a mine for the purpose of working it. BOSCOVICH, Rogeſt Joseph, a very eminent mathemati- cian and philosopher, was born May 11, 1711, at Ragusa. He studied Latin grammar in the schools which were taught by the Jesuits, in his native city, until 1725, when, in consistence with a maxim of the Jesuits, to send their most eminent pupils to Rome for the completion of their education, he was removed to that city. After this he soon acquired very great reputation for his eminent attainments in divinity and science: at three successive periods he became professor of mathematics and astronomy at Rome, at Pavia, and at Milan. When the order of Jesuits was suppressed, he was invited to Paris, and received the place of director of the optical instruments of the marine. Previous to this, however, he had been employed, in conjunction with father Maire, in measuring a degree of the meridian in Italy, and in correcting the maps of the papal state. He published in 1755, an interesting account of the expedition in which these objects were effected. He had also been employed in adjusting a disagreeable affair between the republic of Lucca and the regency of Tuscany; and in a simi- lar business between the republic of Ragusa and the court of Great Britain ; which brought him to London, where he soon became acquainted with the most celebrated British philoso- phers. He remained at Paris ten years, but being a foreigner, his celebrity was envied; this, together with the irreligion which then prevailed among the French philosophers, was disagreeable to him, so that he obtained leave for two years’ absence to revisit his friends in Italy. He tarried at Bassano, where he printed five volumes in large octavo, containing a real treasure of optical and astronomical knowledge. From Bassano he went to Rome, and thence to Milan, where he took up his abode, being in the neighbourhood of his favourite observatory at Brera. Here he continued to enjoy the plea- sures of study; and, occasionally, the society of many respected friends, until his two years of absence were nearly expired: his unwillingness to leave Italy, and at the same time a solici- tude to avoid the charge of ingratitude from the French nation, occasioned great perplexity of mind, which was followed by deep melancholy, a disordered imagination, and, at length, direct insanity. He had, indeed, some lucid intervals, and once there were hopes of a recovery; but he soon relapsed, and an imposthume breaking in his breast, put an end to his mortal existence in February, 1787, in his 76th year. BOSSAGE, in Architecture, a term used for any stone that has a projecture, and is laid rough in a building, to be after- wards carved into mouldings, capitals, coats of arms, &c. Bossage is also that which is otherwise called rustic work; and consists of stones which advance beyond the naked or level of the building, by reason of indentures or channels left in the joinings. These are chiefly used in the corners of edifices, and thence called rustic quoins, The cavities or indentures are º 2 H 118 sometimes round, sometimés chain-främed, or bevelred, some- times in a diamond form, sometimes enclosed with a cavetto, and sometimes with a listel. w BOTANY. The history of the vegetable kingdom, or, as it is termed, Botany, is a science which includes the practical discrimination, the methodical arrangement, and the syste- matic nomenclature, of vegetables. Vegetables are organized productions, supported by air and food, endowed with life, and subject to death, like animals. They have, in some instances, spontaneous, not voluntary motion. They are sen- sible to the supply of nourishthent, the action of the air and light, and thrive or languish according to the wholesome ap- plication of these stimulants. This is evident to all who have ever seen a plant growing in a situation for which it is not suitable. Those who have gathered a rose, know how soon it withers; and the familiar application of its fate to that of human life and beauty, is not more striking to the imagination, than philosophically correct. The external covering of plants is commonly transparent and smooth; but sotnetimes it is downy; and sometimes so hard, that flint has been detected in its composition. The Dutch rush serves as a file to polish wood, ivory, and even brass. Under the cuticle, is found the cellular integument of a pulpy texture, and the seat of colour. It is usually green in the leaves and stems, and is dependent for its hue on the action of light. When the cellular integument is removed, the bark presents itself; in plants and branches only one year old, the bark consists of a simple layer. In the branches and stems of trees, it consists of as many layers as they are years old. The Peruvian bark aſſords “a cooling draught to the fevered lip ;’ that of the cinnamon yields a rich cordial ; that which is stripºéd from the oak, is used for tanning. Immediately under the bark is situated the wood, which forms the great bulk of trees and shrubs. This also consists of numerous layers, as maay be observed in the fir, and other trees; and from these concentric circles, the age of the tree is determined. Within the centre of the wood is the medulla or pith, a cellular sub- stance, juicy when young, extending from the roots to the sum- mits of the branches. In some plants, as in grasses, it is hol- low; merely lining the stem. The trunk enlarges by the forma- tion of the new liher, or inner bark, every year, the undermost layer is transformed into cortea, or outer bark, becoming the laburnam, or soft wood of the next, and the laburnam becoming the lignum, or hard wood. B O T The chemical or elementary principles of vegetables, are, carbon, water, and air; or hydrogen 15 parts, and oxygen 85 parts, for the constituent parts of 100, water; and azote and nitrogen 72, and oxygen 28, as the constituent parts of 100, atmospheric air, and carbon. Vegetables generate or give out oxygen or vital air, in the light or sunshine, by a natural process of their own. The sac- eharine and oily productions of vegetables are parts of their sap or juices; but the turpentine, bitter, and acid principles, are effects of secretion. The green colour of vegetables arises from the oil they contain; the rays of the sun extract the oxygen from the outer surface, and leave the carbon and hydrogen the constituent parts of oil. Healthy vegetables, in general, perspire water by the under part of their leaves, equal to one-third of their weight, every twenty-four hours. Nor do they derive their substance in a principal degree from the mat- ter of the soil in which they grow; but they are created as it were by a vital principle of their own, o&t of air and water, and of the imperceptible matters combined with air and water, from which they derive distinctions of smell, taste, and sub- Stance. - The general constituent principles of vegetables, viz. hydro- gen, carbon, oxygen, &c. do not exist in them in a simple and uncombined state, but joined in various proportions, forming | compound substances, that make up the whole vegetable; and the following are the principal substances met with in vege- tables:—I Mucilage. 2. Fixed and volatile oils. 3. Resin. 4. Gum resins. 5. Caoutehouc. 6. Camphor. 7. Wax. 8. Honey. 9. Sugar. 10. Gluten. 11. Fecula. 12. Tannin. 13. Woody fibre. 14. Colouring matter. 15. Acids. 16. Mis- cellaneous substances.—17. Amber, and 18. Asphaltum, are also supposed to be of vegetable origin. \ & Drötfoſſi ARY &f MBełłANiêAE, SCff:NC#, JB Gy. Tº Mweilage. Various parts of vegetables impart to water, if boiled with them, a certain viscous matter, causing consistency. | This is called mucilage. Some trees suffer their mucilage to . transude, some spontaneoushy, or by incisions made in them. When it has become concrete by drying in the air, it is called gum. In this way gam arabic, gum senegal, and cherry-tree gum, are formed. Mucilage is without taste; soluble in water, but not in oils or alcohol. It is not ehanged by exposure to the air. From the experiments of Cruikshank, it appears to con- sist of oxygen, hydrogen, nitrogen, carbon, and Hime-Fired and Volatile Oils. Oil is composed of carbon and hydrogen, with a small portion of oxygen. Oils are divided into fat or fixed oils, and volatile or essential oils. Fixed oil is usually obtained by expression, chiefly from the seed and kernels of plants. Volatile oil is procured by distilling aromatic plants with water.—Resins exist in the vessels of certain trees, and frequently exude from them spontaneously. Sometimes they are procured by making incisions in the trees, and sometimes by distifling the wood. They are considered as volatile oils conibined with oxygen. They are soluble in alcohol and oils, but not in water. It is this property that renders them so valuable as warnishes. They are very inflammable, and melt with a slight heat. The principal resins are the turpentine, the guaiacum, mastic, copal, and Sandarac.—Gum resins appear to be a natural mixture of resin and mucilage. They are partly soluble in water, and partly in alcohol. Gum ammoniac, assafoetida, and opium, are gum resins.--Caotatehouc, elastic gum, or Indian rubber, resembles a resinous gum. It is elastic, inflammable, and insoluble in water or fat oils. It is partly soluble in volatile oils, and entirely so in nitric ether. It is the juice of a tree of the euphorbia tribe. When first exuded, it is of a milky consistence and colour, but it gradually thick- ens, and is blackened by smoke, as it flows round the clay balls. on which the bottles are made. It is cut easily, if the knife be dipped in water.—Camphor, a volatile oil, is extracted from a species of laurel which grows in China, and the East Indies. It is very inflammable, and sublimes by a gentle heat. It is soluble in ether, alcohol, the oils, and acetic acid. Hi is highly odorous, and prevents the spreading of contagious disorders.— Waar, a vegetable substance, found in the greatest quantity on the anthers of flowers, and collected by bees, is insoluble in water and alcohol, but soluble in volatile and fixed oils. It is very inflammable. Its components are the same as those of volatile oils.-Honey is formed chiefly in the pistils or female organs of ſlowers, whence it is collected by the bees: it appears to be sugar dissolved in mucilage.—Sugar is produced in the greatest quantity from the sugar cane; but it may also be obtained from the sugar maple, the beet-root, carrot, &c. Its constituents are oxygen, carbon, and hydrogen.—Gluten, an elastic viscid substance, is found in vegetables, and chiefly in wheat flour; it is soluble in water, and very slightly so in alcohol.—Fecula, or, Starch, forms the principal part of the substance which is washed away in order to obtain the gluten from the grain. When the fluid is suffered to stand, a white powder subsides, which is the starch. It is also obtained from potatoes.—Tannin matter is found in the gall nut, the bark of oak trees, and other astringent parts of vegetables.— Woody fibre, constituting the basis of wood, may be separated from every other substance, by boiling wood shavings in water to dissolve the extractive matter, and then in alcohol to separate the resins, &c.—Colouring matter is found in vege- tables, combined with, 1, the extractive principle; 2, . with resins; 3, with fecula; 4, with gum.—Acids, existing ready formed in vegetables, are the citric, malic, oxalic, gallic, benzoic, tartaric, acetous, suberic. Besides which, we find various other substances in vegetables, as sulphur, iron, man- ganese, lime, alumine, magnesia, barytes, &c. Roots are necessary to fix and hold plants in the earth, from which they imbibe nourishment. Roots are either annual, or living for one season, as in barley; biennial, which survive one ; winter, and, after perfecting their seed, perish at the end of the | following summer, as wheat; or perennial, which remain and produce blossoms for an indefinite number of years, as those of trees and shrubs in general. The root consists of two parts: the caudea, or stump, which is the body or knot of the reot, from: which the trunk and branches ascend, and the fibrous roots. BOTANY., Z/2 (Zºzº or ///////// 1 //º/, //, ºvº/ .ºz. -- Z%a (///zºo/rºco//v//zrºzºr of Z/e.ſºſ.ſºſyº/. --------- - - - - a 2- - - B O T' B O T DICTIONARY OF MECHANICAL SCIENCE. 119. branching from the cauder.—Buds are, in most instances, [ guarded by scales, and furnished with gum or woolliness, as an additional defence. Buds are various in their forms, but very uniform in the same species, or even genus. They unfold the embryo plant.—The trunk of a tree includes the stems or stalks. The stem, as it advances in growth, either supports itself, or twines round other bodies. It is either simple, as in the fily; or branched, as in other plants.-Leaves are generally so formed as to present a large surface to the atmosphere. When of any other hue than green, they are said to be coloured. The internal surface of a leaf is vascular and pulpy, clothed with a cuticle, very various in different plants, but its pores are always so constructed, as to admit of the requisite evaporation or absorption of moisture, as well as to admit and give out air, and light also acts through this cuticle. The effect of moisture must have been observed by every one. By absorption from the atmosphere, the Heaves are refreshed ; by evaporation, when separated from their stalks, they soon fade and wither. The nutritious juices, imbibed from the earth, become sap, and are carried by appropriate vessels into the substance of the leaves, and these juices are returned froni each leaf into the bark. This is effected by a double set of vessels, analogous to the arteries and veins in animals, and is the circulation of the vegetable blood or sap. The sap is car- ried into the leaves for the purpose of being acted upon by air and light, with the assistance of heat and moisture, and by all these agents, a most material change is wrought in the com- ponent parts of the sap, according to the nature of the secre- tions. The green colour of the leaves is owing to the action of light, but they are subject to a disease by which they become artially spotted or streaked, and in this state are variegated. The irritable nature of leaves is very extraordinary, for the sensitive plant, common in hot-houses, when touched by any extraneous body, folds up its leaves one after another, and the footstalks droop, as if dying. . . Props, or falera, are appendages to the true leaves, or to their stalks. Inflorescence, treats of the different kinds or modes of flowering. Sometimes the flowers surround the stem in a gar- land or ring, as in mint, deadnettle, &c. In other plants, a cluster, which bears several flowers, each on its own stalk, like a bunch of currants. In other plants, numerous crowded flowers are ranged along an upright, common stalk, expanding pro- gressively, as in wheat and barley. Again, we find a flat-top- ped spike, as in the cabbage and wallflower. - Fructification is a term comprehending not only the parts of the fruit, but those of the flower. The parts of fructification are described by many technical words, but include chiefly the flowercup, or external covering of the flower; the calix, con- sisting in general of the coloured leaves of the flower; the stamens, and the cells containing the pollen or fecundating dust: the pistils stand in the centre of the cireles formed by the stamens, and consist of the germen or rudiments of the future fruit or seed; the seed are composed of the embryo or germ, and are often accompanied by accessory parts ; as spines, hooks, scales, and crests, generally serving to attach such seeds as are furnished with them, to the rough coats of animals, and thus promote their dispersion. Classification, though last in order, is first in importance; and of all the systems of botany, that of Linnaeus, now gene- rally acknowledged and adopted, is founded on the number, situation, and proportion of the stamens and pistils, whose tises and structure have been just explained. The following twenty-four Classes owe their distinctions principally to the StamenS. The CLAsses; or, Primary Divisions of the Seasual System. (See the Plate.) Fig. T. MonANDRIA, flowers with one stamen.—2. DIANDRIA, flowers with two stamens.—3. TRIANDRIA, flowers with three stamens.—4. TETRANDRIA, flowers with four stamens, all of the same length.-5. PenTANDRIA, flowers with five stamens.— 6. Hex ANDRIA, flowers with six stamens, all of the same length.-7. Hept ANDRIA, flowers with seven stamens.—8. Oct ANDRIA, flowers with eight stamens. – 9. ENNEANDRIA, flowers with nine stamens.—10. DECANDRIA, flowers with ten stamens.—11. DoDECANDRIA, flowers with twelve stamens. SYNG ENESIA ; exhibit the union of the stamens by the anthers.—21, 22, 23. -12. Icosa NDRIA, flowers with about twenty stamens, attached to the calix, or sometimes, in part, to the corolla.-13. Poly- ANDRIA, flowers most commonly with more than twenty sta- mens, attached to the receptacle.—14. DiDYNAMIA, flowers with two longer stamens.—ió. TetkADY NAM1A, flowers with four longer stamens.—16. MonADELPHIA, filaments united into one brotherhood.—17. DIADeLPHIA, filaments forming two brotherhoods,-18. PolyADeLPHIA, filaments forming more than two brotherhoods.-19. SYNG enesiA, anthers united, com- posing a hollow cylinder, through which the style passes.—20, GYNANDRIA, stamens on the pistil.—21. Mosq.ci A, stamini- ferous and pistiliferous flowers on the same plant.—22. Dioeci A, staminiferous and pistiliferous flowers on different plants.-23. PolyGAMIA, different dispositions on the same plant.—24. CRYPTOGAMIA, flowers inconspicuous. THE ORDERs; or, Secondary Divisions of the Sexual System. Fig. 1. Monogynia, containing hermaphrodite flowers with one pistil, or female organ.—2. Digynia, hermaphrodite flowers with two pistils; a, the pistiſs detached from the flower.—3. Trigynia, hermaphrodite flowers with two pistils; a, the pis- tiſs separated from the flower.—4. Tetragynia, hermaphrodite flowers with four pisti's ; a, the pistils separated from the flower.—5. Pentagynia, hermaphrodite flowers with five pistils; a, the pistils separated from the flower. —6. Hewagynia, hermaphrodite flowers with six pistils; a, the pistils separated from the flower.—7. Heptagynia, hermaphrodite flowers with Seven pistils ; a, the pistils detached from the flower.—8. Pecagynia, hermaphrodite flowers with ten pistils; a, the pis- tils separated from the flower.—9. Dodecagynia, hermaphrodite flowers with twelve pistils, or female organs.—10. Polygynia, hermaphrodite flowers containing an indefinite number of pis- tils, or female organs.—11. Gymnospermia, the name of the first order in the class DJ DYNAMIA ; in which a represents a longitudinal section of the flower, to display the four naked seeds in the bottom of the calix,−12. Angiospermia, the name of the second order in the class DIDYNAMIA, containing such hermaphrodite flowers with four stamens, two longer than the others, as have their seeds contained in a vessel; a, the peri- carp, or vessel, detached from the flower.—13. Siliculosa, the first order in the class Tetra DYNAMIA, containing such flowers possessed of the classical character, as have their seeds con- tained in a short round pod ; a, the silicula, or pod, divided, to shew the seeds separated from the flower.—14. Siliquosa, the second order in the class TETRADYNAMIA, containing such flowers possessed of the classical character, as have their Seeds contained in a siliqua, or long slender pod, to each suture of which they are alternately attached; a, the siliqua detached.— 15. Polygamia Aºqualis, the first order in the class SYNG EN E- SIA ; a, a floret separated from the aggregate.—16. Polygamia Superflua, the second order in the class SYNGEN esſa ; a, represents a female floret in the circumference or ray; b, an hermaphrodite floret in the centre or disk.—17. Polygamia Frustranea, the third order in the class SYNG ENESIA.—18. Polygamia Necessaria, the fonrth order in the class SYNGENE- SIA.—19. Polygamia Segregata, the fifth order in the class SYN- GENESIA ; a, a floret with its proper flower-cup detached from the aggregate.—20. Monogamia, the sixth order in the class a, representing a section of the flower, to Triaccia, the third order in the class PolyG AM 1A, in which her- unaphrodite flowers are intermingled with male or female. ſlowers, or both, on one, two, or three plants.-24. Filices, Ferns, the first order; 25. Musci, Mosses, the second order; 26. Algae, Sea-weed, &c. the third order; 27. Fungi, Mush- rooms, the fourth order; in the class CRYPTogAM L.A. In the class CRYPtoGAMIA two other orders are reckoned, viz. Hep ATICE, small herbaceous plants resembling Mosses; and MISCELLANEE, including plants not easily referable to any of the five foregoing orders. The orders, or subdivisions of the classes, are generally. marked by the number of the pistils, or by some other circum- stance equally intelligible. The names of these, as well as of the classes, are both of Greek derivation, and designate the functions of the respective organs. A further division of the orders, founded on distinctions in the nectarium, lead to: 120 B O W B. R. A. DICTIONARY OF MECHANICAL SCIENCE. genera. Other divisions of the genera, in regard to the root, trunk, leaves, &c. lead to species; and casual difference in species are called varieties. tº - - * We have, in the American reed, an instance of the Monandria monogynia, that is, a flower with one stamen and one pistil. . In the jasmine we see an instance of the Diandria monogynia, or flower that has two stamens and one pistil. In the linum or flax, there are five stamens and five pistils; and the flower is called Pentandria pentagynia, that is, one having five males and five females; and so of the rest. The study of Botany has been applied as a guide to estimate the qualities of plants. The first order of the fourteenth class, denominated “Didynamia gymnospermia,” are all innocent or wholesome; those of the other order are febrile, narcotic, and dangerous, being allied to a large part of the Pentandria mono- gynia, known to be poisonous, as containing henbane, night- shade, and tobacco. The whole class Tetradynamia is whole- some. Whenever the stamens are found to grow out of the calyx, they indicate the pulpy fruits of such plants to be whole- some, except the seeds of the laburnum, which, if eaten unripe, are violently emetic and dangerous. {e t rally to be suspected. Umbelliferous plants, which grow in dry or elevated situations, are aromatic, safe, and often whole- some, while those that inhabit low and watery places are among the most deadly poisons. The natural substances found in all vegetables are, sugar, in the sugar-cane, beet, carrots, &c.; gum, or mucilage, oozing from many trees; jelly, procured from many fruits; turpentine and tar, from the pine ; bitters, from hops and quassia; and the narcotic principle from the milk of poppies, lettuce, &c. The vegetables of greatest value to man, produce gluten or starch; as wheat, potatoes, barley, beans, &c. Oils are pro- duced by pressing the seeds or kernels of vegetables; as olives, almonds, linseed, &c. Volatile oils are distilled from peppermint, lavender, &c. Wax is collected from all flowers by bees. Resins exude like gum from firs and other trees; and are known as balsams, varnishes, turpentine, tar, pitch, &c. Of this class too, is Indian rubber; which is a gum that exudes from a certain tree in South America. And iron also mixes with the substance of most vegetables, and is the cause of the beautiful colours of flowers. Potash is obtained from the ashes of burnt vegetables; as kelp, vine, fern, &c. Anatomy of Plants.—In order to comprehend this subject, the following general principles may be of service; they may be verified in most plants; and observation is here the best teacher. First, all plants do not perspire. 2. That there is not in all plants an uniform circulation of sap. 3. In general, the spiral wire is the muscle of the plant. 4. The leaves are for the most part the lungs of the plant. 5. The different divisions of the leaves are formed of the elongations of the bark and inner bark vessels. 6. Hairs and instruments of that kind are the means which Nature takes to form the different juices according to their various affinities. ...That these figures were taken for perspiration, but are in reality liquids received from the atmosphere and flowing into the plant, not a juice running from it. 7. The root is the grand laboratory of all plants, where the great chemical operations are going on. , 8. The heart of the seeds is formed in the extremities of the side roots. the pollen in the tap root. 10. The corolla of a flower is formed by bubbles of water placed in rows, and owes all its beauty, and the lightness of its tint, to the refraction and reflection of the sun on the drops of water which form its pabulum. This thought of apparent subtilty is nevertheless verified by experi- ment. 11. The roots and leaves of a plant will most exactly mark not only what is the soil in which they originally grew, but the situation from which they came, whether a water plant or a dry plant, a rock or a valley plant, &c., 12. The water, semi-water, and rock plants alone can be said to have direct. air-vessels, though these may be found in parasite and early spring plants, such as the crocus and hyacinth. BOWSPRIT, a large boom or mast, which projects over the stem, to carry sail forward, and counteract the force of the aftersails, or those extended behind. The bowsprit should be. two-thirds of the length of the mainmast, and its thickness equal to the mizenmast: when it is twelve fathoms five feet Milky plants are gene- 9. The flower is also formed in the middle root, and long, its yard must be eight fathoms two feet long, and the top- mast of the bowsprit three fathoms and one foot. • BOYLE, Robert, one of the greatest philosophers of the seventeenth century, was born at Lismore, in Ireland, January 25, 1626, the year in which the sciences were deprived of their greatest ornament, Lord Bacon, whose plans of experimental . philosophy our author afterwards so ably seconded and im- proved. Boyle was one of the first of those illustrious men who formed the Royal Society, in 1645, for the purpose of improving experimental knowledge, upon the plan laid down by Bacon; which society being, in 1654, removed to Oxford, he went to reside there, where he very much improved the air- pump, which led him to the discovery of several of the proper- ties of air. He also published, during his residence at Oxford, several works relating to the properties of air, and other phi- losophical subjects; and in 1668 returned to London, where he continued to reside till his death, which happened in the year 1691, in the 65th year of his age. Boyle was author of a very great number of important works, beautiful editions of which have been published in London, in five volumes folio, and six volumes quarto. Dr. Shaw also published, in three volumes quarto, the same works “abridged, methodized, and disposed under the general heads of Physics, Statics, Pneumatics, Natural History, Chemistry, and Medicine;” to which he has prefixed a short catalogue of the philosophical writings, accord- ing to the order of time when they were published, &c. BRAHE, TYC Ho, a famous Danish astronomer, born of a noble family, in Knudstorp, 1546, read lectures on astrono- my at Copenhagen, in 1574, by order of the king ; who also built for him an observatory in the isle of Huen in the Sound, the building being called Uranibourg, where he resided about 20 years, pursuing his studies, making observations, and receiving visits from the most illustrious personages. On the death of the king he lost his pension, and went to Prague, where he was introduced to the emperor Rodolphus : who treated him respectfully; gave him a magnificent house, fit for astronomical observations; and assigned him a pension of 3000 crowns. Here then he settled in the latter part of 1598, with his sons and scholars, and among them the celebrated Kepler. But he did not long enjoy this happy situation; for, about three years after, he died, in the 55th year of his age, and was interred in a very magnificent manner in the principal church at Prague, where a noble monument was erected to him ; leaving, beside his wife, two sons and four daughters. The skill of Tycho Brahe in astronomy is universally known, and his works are very numerous and valuable. - BRAMAH'S MACHINE, or Hydrostatic Press, &c. consists in the application of water, or dense fluids, to engines, so as, in some instances, to cause them to act with immense force ; in others, to communicate the motion and powers of one part of a machine to some other part of the same machine ; and, lastly, to communicate the motion and force of one machine to another, where local situations preclude the application of other methods of connexion. - The first and most material part of this invention will be clearly understood by an inspection of the figure in the next page, where A is a cylinder of iron, or other materials, suffi- ciently strong, and bored perfectly smooth and cylindrical; into which is fitted the piston B, which must be made perfectly water-tight, by leather or other materials, as used in pump- making. The bottom of the cylinder must also be made suffi- ciently strong with the other part of the surface, to be capable of resisting the greatest force or strain that may at any time be required. In the bottom of the cylinder is inserted the end of the tube C; the aperture of which communicates with the inside of the cylinder, under the piston B, where it is shut with the small valve D, the same as the suction-pipe of a common pump. The other end of the tube C communicates with the small forcing-pump or injector E, by means of which, water or other dense fluids can be forced or injected into the cylinder A, under the piston B. Now, suppose the diameter of the cylinder A to be 12 inches, and the diameter of the piston of the small pump or injector E only one quarter of an inch, the proportion between the two surfaces or ends of the said pis– tons will be as 1 to 2304; and supposing the intermediate space between them to be filled with water or other dense B. R. A B R A 191 DICTION ARY OF MECHANICAL SCIENCE. fluid capable of sufficient resistance, the force of one piston will act on the other just in the above proportion, viz. as 1 is to 2304. Suppose the small piston in the injector to be forced down when in the act of pumping or injecting water into the cylinder A, with the power of 20 cwt. which could easily be done by the lever H ; the piston B would then be moved up l with a force equal to 20 cwt. multiplied by 2304. Thus is constructed a hy- dro - mechanical engine, whereby a weight amount- ing to 2304 tons can be raised by a simple lever, through equal space, in much less time than could be done by any appa- ratus constructed on the known principles of me- chanics; and it may be proper to observe, that the effect of all other mechani- cal combinations is coun- | teracted by an accumulated ſ WBN Hºl \–lkº complication of parts, which renders them incapable of - being usefully extended be- “ --— —r—- . . ; yond a certain degree; but in machines acted upon or constructed on this princi- ple, every difficulty of this - - kind is obviated, and their == power subject to no finite —C restraint. To prove this, T - . . it will be only necessary to remark, that the force of any machine acting upon this principle can be increased ad infini- tum, either by extending the proportion between the diameter of the injector and the cylinder A, or by applying greater power to the lever H. The second figure represents the section of an engine, by which very wonderful effects may be produced instanta- neously by means of compressed air. A A is a cylinder, with / \ the piston B fitting air-tight, in the same manner as described in the first figure. C is a globular vessel made of copper, iron, or other strong materials, capable of resisting immense force, similar to those of air-guns. D is a strong tube of small bore, in which is the stop-cock E. One of the ends of this tube communicates with the cylinder under the piston B, and the other with the globe C. Now, suppose the cylinder A to be the same diameter as that in the first figure, and the tube D equal to one quarter of an inch diameter, which is the same as the injector, in the same figure ; then, suppose that air is in- jected into the globe C, (by the common method,) till it presses against the cock E with a force equal to 20 cwt. which can easily be done; the consequence will be, that when the cock E is opened, the piston B will be moved in the cylinder AA with a power of force equal to 2304 tons; and it is obvious, as in the case in the first figure, that any other untimited degree of. force may be acquired by machines or engines thus constructed. The third figure is a section, merely to shew how the power and motion of one machine may, by means of fluids, be transferred or communicated to another, let their distance and local situation be what they may. A and B are two small tubes, smooth and cylindrical ; in the inside of each of which is a piston, made water and air tight, as in the first and second figures. C C is a tube conveyed under ground, or otherwise, from the bottom of one cylinder to the other, to form a com- munication between them, notwithstanding their distance be ever so great; this tube being filled with water or other fluid, until it touch the bottom of the piston ; them, by depressing the piston A, the piston B will be raised. The same effect will be produced vice versa; thus, bells may be rung, wheels turned, or other machinery put invisibly in motion, by a power being applied to either. -- The fourth figure is a section, shewing another instance of communicating the action and force of one machine to another; and how water may be raised out of wells of any depth, and at any distance from the place where the operating | power is applied. A is a cylinder of any required dimensions, in which is the working piston B, as in the foregoing examples: $ into the bottom of this cylinder is inserted the E tube C, which may be of less bore than the cylinder A. This tube is continued, in any required direction, down to the pump cylinder D, supposed to be fixed in the deep well E E, and forms a junction therewith above the pis- ton F; which piston has a rod G, working through the stuffing-box, as is usual in a com- mon pump. To this rod G is connected, over a pulley or otherwise, a weight H, sufficient to overbalance the weight of the water in the tube C, and to raise the piston F when the piston B is liſted : thus, suppose the piston B is drawn up by its rod, there will be a vacuum made in the pump cylinder D, below the piston F; this vacuum will be filled with water through the suction pipe, by the pressure of the atmosphere, as in all pumps fixed in air. The return of the piston B, by being pressed downwards in the cylinder A, will make a stroke of the piston in the pump cylinder D, which may be repeated in the usual way by the motion of the piston B, and the action of the water in the tube C. The rod G of the piston F, and the weight H, are not necessary in wells of a depth where the atmosphere will overbalance the water in the suction of the pump cylinder D, and that in the tube C. The small tube and cock in the cistern . I are for the purpose of charging the tube C.—By these means, it is obvious, most commodious machines, of prodigious power, for tearing up trees, &c. and susceptible of the greatest strength, may readily be formed. If the same multiplication of power be attempted by toothed wheels, pinions, and racks, it 2 I 122. B R. E. B R A DICTIONARY OF MECHANICAL SCIENCE. is scarcely possible to give strength enough to the teeth of the racks, and the machine becomes very cumborsome and of great expense. But Mr. Bramah's machine may be made abundantly strong in a very small compass. It only requires very accurate execution. Mr. Bramah, however, was greatly mistaken, says Dr. Gregory in his Mechanics, when he pub- lished it as the discovery of a new mechanic power. The principle on which it depends has been well known for nearly two centuries; and it is matter of surprise that it has never before been applied to any useful practical purpose. BRANDY. The genuine spirit is distilled from wine, (pro- perly so called, being the wine of grapes,) also from the lees of wine, and the husks of the grapes which remain after pressing out the juice. The usual apparatus is employed, of a still that holds five or six quintals, with a capital and worm applied in the usual manner. Brandy has a purer and more vinous taste than other spirits; its peculiar flavour, no doubt, depends on the nature of the volatile principles, or essential oils, that rise in distillation with the pure spirit, and likewise in some mea- sure upon the wood of the cask in which it is kept. ... The brandies made in France are much preferred to those of Spain and other countries. This preference is, perhaps, as much owing to superior distillation, as to certain peculiarities in the flavour of the grapes, which differ on every soil and in every climate. In the south of France alone, there is a great variety in the grapes, as well as in the quality of the spirit extracted from them. Some wines are considered totally unfit for distil- lation; others peculiarly suited for it, and unfit for wine. When the fermentation has proceeded too far, the wine is put into the still, and the spirit extracted; otherwise the acetous acid, by the continuance of the fermentation, would be soon produced in such abundance, as to turn the whole liquid into vinegar. The inferior weak wines are generally employed for the making of brandy, from their containing too little spirit to keep them ; and the good, strong wines, are generally reserved as yielding a far ampler profit than could be obtained by the extraction of their spirit. The most spirituous wines of France, are those of Languedoc, Guienne, and Rousillon, which yield, according to Chaptal, from twenty to twenty-five gallons of excellent brandy out of a hundred; but those of Burgundy and Champagne much less. Brisk wines, which contain much carbonic acid, from the fermentation having been stopped at an early period, yield the least spirit. The brandies generally esteemed as the best and finest flavoured are those distilled from the grapes which are the produce of the territories of Cogniac and Andaye, Hence every wine merchant in England is professedly stocked with the “real Cogniac" brandy; and thus every public-house sells no other brandy than the “best Cogniac;”——even the distiller him- self has the “genuine Cogniac,” which he will tell you he has received “circuitously,” and truly so, for it has made all the revolutions of his still-worm in its passage to him. In distil- lation, the three principal distinctions, in the various strengths of spirits, are described by the terms, low wines, proof spirit, and alcohol. Low wines consist of one-sixth of pure spirit, or alcohol, to five of water;-proof spirit consists of one half of alcohol, and one half of water; and alcohol, wholly of pure spirit. * *ANDENBURGIUM Scept RUM, the Sceptre of Branden- burg, is a modern constellation, formed in 1688, by Geoffroi Kirch, one of the first astronomers of the Duke of Prussia, This asterism is easily distinguished by four stars, situated nearly perpendicular to the equator, and lying between the turn of the river Eridanus, Orion, and the Hare ; and these constellations define the boundaries of this insigne regiminis, BRASS, Making of Brass is a factitious metal, made of copper and zinc. By long calcination alone, and without the mixture of any other substance, brass affords a beautiful green or blue colour for glass; but if it be calcined with powdered sulphur, it will give a red, yellow, or chalcedony colour, accord- ing to the quantity and other variations in using it. Brass is of a yellow colour, more fusible than copper, and not so apt to tarnish. Pure brass is not malleable unless hot; when cold it will break, and will not bear the hammer when it has been twice melted. To render it soft and pliable, and capable of being wrought, seven pounds of lead are added to an hundred weight of brass. It is peculiarly adapted for wire, being capable of great extension, and is much used in watch-work. Corinthian brass, so famous in antiquity, was a mixture of gold, silver, and copper. Brass colour is a preparation intended to imitate brass; of which there are two sorts, the red brass or bronze, and the yellow or gilt brass; the last is made only of copper filings; with the former, red ochre, finely pulverized, is mixed, but both are used with varnish. The appearance of brass is given to other metals, by washing then with a yellow lacquer or varnish, much to the detriment of the manu- factured article. Gold lacquer for brass-work may be thus made :-Put an ounce of turmeric powder, two drachms of anatto, and two of saffron, into a pint of alcohol, shake the whole occasionally during a week, and then filter it into a clean bottle. Three ounces of clean seed-lac are then to be added, and the bottle shook occasionally during a ſortnight. The mixture will now be a fine lacquer for brass, which will give that metal the appearance of burnished gold. In using it, the metal should be just warmed, and the varnish be laid on evenly with a brush, passing it directly across the work. Small articles may be dipped in the lacquer. BREAD, the staff of life, is used by all people in one way or another, even though composed of matcrials very dissimilar. We use wheaten bread; some use bread made of oats, others convert dried fish into meal for bread; and nature furnishes the bread-fruit tree to natives of the South-Sea islands. The bread-fruit tree grows abundantly on the Ladrone Islands. In the Society Islands it is as large as a moderate sized oak ; its leaves are about a foot and a half long, of an oval shape, like those of the fig-tree, which they resemble in colour; and, when broken, exude a milky juice. The fruit is shaped like a heart, and grows to the size of a child's head. Its rind is thick, green, and covered with excrescences. The internal part of the rind is a pulpy substance, full of twisted fibres; this pulp is softcr towards the middle, where a small cavity is formed, containing no kernels or seeds. It aſſords much nourishment, and is very satisfying. Its taste is harsh, and similar to potato-bread. The cassiva bread of the Ame- ricans is made from a species of starch prepared from the roots of a plant. They are peeled and pressed; the juice which exudes is a deadly poison, used by the Indians to poison their arrows. The white starch, however, which is deposited, when properly washed, is perfectly innocent, and makes bread. The materials of which loaf-bread is principally made, are the seeds of farinaceous vegetables, as wheat, rye, and barley. Potatoes, oats, beans, pease, rice, maize, millet, buck-wheat, &c. contain no gluten, and cannot be made into bread without a certain quantity of flour. The component parts of wheaten, barley, and rye flour, are starch, gluten, and saccharine mucilage. Fecula, or starch of wheaten ſlour, forms the most nutritive part of grain. It is ſound in all seeds, and is very abundant in the potato, as almost all the root consists of starch. 2. Gluten, is the principal substance contained in wheaten flour. It is necessary for the production of good light bread ; the quality of the bread being exactly in proportion to the quantity of the gluten contained in the flour; wheat flour alone contains it in any considerable quantity. Flour could not be made into bread without gluten, for the dough rises in consequence of this substance. To obtain gluten, you put a handful of flour into a cloth, pass it through water, and press it with the hand; the starch or fecula passes off, and this elastic substance remains. Gluten forms one-fifth part of bread - corn, fer- ments readily, and is soluble in acids, but not in water. 3. Saccharine mucilage is soluble in cold water, and separable from it by evaporation. The saccharine part may be converted into an ardent spirit, but the mucilage in bread that has been kept some time, tends to acidity, and becomes mouldy. There are three general methods of making bread, and these we will now illustrate :-1. Unleavened bread is made of flour mixed with water. The sea and other biscuits, the Jews' passover cake, the oaten and barley bread of Scotland, are of this nature. 2. Leavened bread, mentioned in the Jewish history, has been known to mankind from the earliest age of society. It is thus made : A portion of dough is left till it ferments, or becomes sour. This is mixed with other dough, and causes it to rise ; carbonic acid gas is thrown out, a vinous smell is JB R. E B R E DICTIONARY OF MECHANICAL SCIENCE. 123 perceived; and an active fermentation goes on. 3. Bread made with yeast, or family bread, is thus made. To half a bushel of wheaten flour add six or eight ounces of Salt, a pint, of yeast, and six quarts of water. Mix the whole together, and cover it up with a blanket; this operation is called setting the sponge: flour must then be added, and the mass kneaded till it attain a proper consistency. It must then stand for four or five hours, till it rises properly, and afterwards you put it into the oven. A sack of flour contains about 280 lbs. and will make eighty quartern loaves, allowing three and a half pounds of flour for each. Before the loaf goes into the oven it weighs 4 lbs. 15 oz. but loses nine or ten ounces in baking. In each loaf bakers usually put two ounces of alum, though this is prohibited by law. The alum binds the bread, and makes it more compact, but then it is less wholesome ; and it also whitens old flour. Besides the bread just described, there are wheaten and house- hold bread. The former is made of flour, with a mixture of the finer bran ; the latter of the whole substance of the grain, without either taking out the coarse bran or the fine flour. French bread is made by adding ten cggs, and a pound and a half of fresh butter, and as much yeast, to half a bushel of fine flour. The whole mass is tempered with new milk, warmed pretty hot; after being allowed half an hour to rise, it is made into loaves, or rolls, and is washed over with an egg beaten with milk; the oven is of a gentle heat. Bread is highly nutri- tious. And since, among the animal fluids the saliva is essen- tially necessary, dry food should be used as a stimulus to draw it forth ; thence we cat bread with meat. Bread blends the oil and water of food in the stomach, which it stimulates; and it is peculiarly proper for that purpose, being bulky without too much solidity, and ſirm without diſliculty of Solution. BREAKWATER, a sort of small buoy fastened to a large one, when the buoy-rope of the latter is not long enough to reach to the surface of the water ; and thereby to shew where the large buoy swims. Breakwater signifies also the hull of an old ship sunk at the cntrance of a small harbour, to break off or diminish the force of the waves as they advance towards the vessels moored within. The great Breakwater across the bay of Plymouth, which has been going on for years, and is not yet finished, is the greatest of the kind ever undertaken in the kingdom. The exposed situation of the sound has been long and severcly felt as an extreme inconvenience in the harbour, and it was at last determined to oppose, if possible, some bar- rier to the heavy swell which is here almost continually rolling in from the Atlantic. The plan at last adopted, with the advice of the most experienced engineers, men of science, and naval officers, was, to construct at St. Carlos rocks, about three miles south of Plymouth, a mole, or vast heap of stones, in the mid- dle of the sound, stretching across its entrance, occupying nearly half of its width, and leaving a free passage for vessels, both on the eastern and western shores. The whole expense was estimated at £1,171,100, viz. £1,051,200 for the mole or breakwater, and £119,900 for a pier along the top, with light- houses. It was proposed, that the breakwater should begin 360 feet on the eastward of St. Carlos rocks, and extend 1800 feet west of the Shovel rock ; the whole length to be 1700 yards, or very nearly a mile, 4000 fect in the middle being quite straight, and the two extremities having a slope up the sound. It was estimated, that 2,000,000 tons of stone would be required to finish it; and it was advised to heap them pro- miscuously together in large blocks, not less than 1; or 2 tons weight cach, leaving them to find their own base and position. Where the water was 30 fect deep, the dimensions of the breakwater were to be 40 feet high, 30 feet across the top, and 210 feet wide at the foundation. The work was begun in 1812; the first stone was sunk on the 12th of August; and on the 31st March, 1813, the building began to make its appearance above the surface of low water at spring tides. The stones were quarried from a rock of limestone or gray marble, purchased from the Duke of Bedford for £10,000, and situated on the eastern shore of Catwater. More than fifty vessels, of peculiar construction, were employed in carrying the stones to the work, many of which were five tons and upwards each. On the whole, this great work has been conducted with much skill and surprising despatch, and the result has fully answered the ex- pectations of its projectors. At the end of the second year, the swell was so much broken, that ships of all sizes ran in, and anchored with confidence behind the breakwater. Since that time 200 sail of vessels of every description have here ſound shelter, and 25 or 30 sail of the line muay now ride here at all times, in security. The Eddystone lighthouse is an important appendage to the harbour, without which the entrance to the harbour would be extremely dangerous. See Eoo Ysto N.E. BREAMING, burning of the filth, such as grass, ooze, shells, or Sca-weed, from the ship's bottom, which it has con- tracted by lying long in harbour; it is performed by holding kindled furze, faggots, or reeds, to the bottom, which, by melt- ing the pitch that formerly covered it, loosens whatever ſilth may have adhered to the planks; the bottom is then covered anew with a composition of sulphur, tallow, &c. which not only makes it smooth and slippery, so as to divide the ſluid more readily, but also poisons and destroys those worms which cat through the planks in the course of a voyage. This operation may be performed either by laying the ship aground after the tide has ebbed from her, or by docking, or careening. 13REWING. Brewing is a very ancient domestic art. Before the malt is used it must be bruised between rollers ; and soft water is used for mashing and fermentation. The first step in brewing is mashing. This is done in a tub ſurnished with a ſalse bottom, pierced with holes, and moveable, or fixed a few inches above the real bottom. There are two side-open- ings between the two ; to one is fixed a pipe to convey water into the tun, and the other is used for drawing the liquor out. The malt is to be strewed over the false bottom, and a proper quantity of water let in from the upper copper; after which, the mass is beaten by poles, or a machine like a rake or har- row, and moveable on a perpendicular beam, with transverse arms for the rakes. When the mashing is completed, the tun is covered to prevent the escape of the heat, and the whole is Suſſered to stand, that the insoluble parts may separate from the liquor; the side-hole is then opened, and the clear wort discharged into the lower copper. The most cligible tempera- ture in mashing is from 185 to 190 degrees, but for the first mashing the heat of the water must be less, and so in propor- tion to the dark colour of the malt. The wort of the first mashing is always the richest in saccha- rine matter; but to exhaust the malt, a second and third mash- ing arc requisite.” Thirty gallons may be drawn from each bushel of malt, for sound small beer; six and a half gallons only for strong ale. Every bushel of malt absorbs, or retains, abbºt three and a half gallons of water. The next process is boiling and hopping; if only one kind of liquor is to be made, the produce of the three mashings should be mixed; if both ale and *ble-beer are required, the wort of the first, or first and second mashings, is for the ale, and the remainder for the beer. The wort intended for the same liquor, after it comes from the tun, is put into the lower copper, and mixed with a proportion of hops ; and the better the wort, the greater the quantity of hops will be wanted. Hops contain gallic acid and tanning matter, and deprive the swect wort of the mucilage, which occasions the beer to keep without turning sour. After the hops have been mixed with the wort in the copper, the liquor is made to boil as fast as possible, when it is discharged into shallow tubs, called coolers, where it remains till it is cool enough to undergo fermentation. From the coolers the liquor is transferred to the working tun, and with it is mixed a gallon of yeast to four barrels of beer. In four or five hours the fermentation conmences, but it requircs from 18 to 48 hours before the wort is ſit to be bar- relled. The fermentation still goes on in the barrels, and in a few days a copious discharge of yeast takes place from the bung-hole, and the greater portion of gluten is disengaged. In brewing, the gluten is not wanted, but in bread is indispen- Sable, and alone renders it fit for use. Care must be taken to fill up the barrel every day with fresh liquor; this discharge lessens daily, and ends entirely in about a week, when the bung-hole is closed, and the liquor is fit for usc, after standing * Hrowers use a sacchrometer to ascertain the goodness of the wort. This instrument is a kind of hydrometer, and shews the specific gravity of the wort, ratiſer than the exact quantity of saccharine matter contained in it. T24 B R I B. R. I DICTIONARY OF MECHANICAL SCIENCE. from a fortnight to three months, according to its 'strength, and the temperature at which it has been fermented. The fining of the beer is done by the use of isinglass. But drugs are sometimes used, to give a narcotic and stupefying power to the beer. • . r º Ale, a fermented liquor extracted from malt, has a less pro- portion of hops than beer. It was first made in Egypt as a substitute for wine, and was a favourite drink with the Anglo- Saxons and Danes. Pale ale is accounted more wholesome than brown ale, because it is brewed from malt slightly roasted, while the latter is made of drier malt. To make malt, barley is steeped in cold water, not less than 40 hours. When it is sufficiently steeped, the water is drained off, and the barley spread upon the malt floor, where it is formed into a rectangular heap. about 16 inches deep. In this state it remains about 26 hours. It is then turned with wooden shovels, and diminished in depth : this is repeated . twice or thrice a day, and the grain is constantly spread, till its depth does not exceed a few inches. On the couch it absorbs oxygen from the atmosphere, which it converts into carbonic acid; the temperature gradually increases, and in four days the grain, now ten degrees hotter than the atmosphere, be- comes moist, and exhales an agreeable odour: this is termed the sweating. The maltster must keep the temperature from becoming excessive, by turning. At the period of sweating, the roots of the grains appear. In one day after the sprouting of the roots, the rudiments of the future stem, called the acrospire, may be seen to lengthen. As it shoots along the grain, the mealy part undergoes a considerable change : the glutinous and mucilaginous matter is taken up and removed, the colour becomes white, and the texture so loose that it crumbles to powder between the fingers. When the acrospire has come nearly to the end of the seed, the process is stopped by drying the malt upon a kiln. It is then cleaned. When the grain is dried gradually, or in the sun, it is called air-dried malt; or when quickly, by the heat of a stove, kiln-dried; the latter being charred partially, is brown, more or less intense, and contains less fermentable matter than the air-dried, or pale malt. Burnt sugar is frequently used to colour beer. BRIDGE, an artificial mode of conveyance from one part of space to another, the intermediate part being either impass- able, or difficult, or otherwise of inconvenient access. Among the ancients, the Greeks borrowed, with their science, their knowledge of architecture, and consequently of bridge-making, from the Asiatics; and of these last, the Chinese attainadº degree of perfection, which neither Greece nor Rome ºf boast. From time immemorial, chain bridges have pºssed from acclivity to acclivity, a distance in some insº 600 feet, the height of the arch being 750 feet; and t snan | º º ". bridge (of wood or boats) that Darius built over the Propontis, or the Dardanelles, to pass from Asia into Europe, surpasses all the modern military bridges. But this is outdone by the bridge of Trajan over the Danube, which one cannot sufficiently admire; for though all the works of this emperor were magnificent, yet this structure, 4770 feet long, supported by twenty piers of square stone, each pier 150 feet high above the foundation, 60 feet in breadth, and 170 feet from each other, does equal honour to the wise policy of the Roman, and his eastern architect, Apollodorus of Damascus. - Among the moderns, Belidor, an engineer, directs that the piers be one-fifth, or at least one-sixth, of the opening; and the arch stones ºth part of the opening: in general, that the pier ought to be of that strength, that it will support its arch as an abutment; which, by practice, he finds to be one-fifth or one- sixth ; but gives as a rule, one-sixth and two feet more. For 36 example, an arch of 36 feet should have a pier of F + 2 = 8 feet. In an arch of 72 he makes the pier 14 feet, viz. two feet more than one-sixth. Gautier, another engineer, differs only from Belidor as to the length of the arch stones; which in arches of 24 feet ought to be 2 feet; if 45, 3 feet; if 60, 4 feet; if 75, 5 feet; if 96, 6 feet, when the stone is of a durable material; but of greater dimensions, when the stone is soft, and easily decomposed : side by four feet. and an arch stone of 6 feet, of durable material, will suffice for an arch of 150, or even 200 feet. See, in the sequel, A Table. for the Tºhickness of Bridges. . - ºn - “, London Bridge, (see Plate, Bridges,) planned by Peter of Collchurch, a priest, .has its piers much stronger, being more than half the opening ; the piers being from 25 to 34 feet, 18 in number, the width of the river being only 900 feet. This bridge is now being supplanted by a more capacious structure, which has this year, 1824, been begun to be built; and of which we shall speak in the close of this article. * n The piers of Westminster Bridge, (see Plate, Bridges,) are 17 feet, the breadth of the river 1223 feet, the arches semicir- cular; the spring commencing about two feet above low-water mark. There are thirteen large and two smaller arches; the centre arch is 76 feet span, and the others decrease on each The passage for carriages is of very difficult ascent, the rise being 30 feet in a distance of 611.5 feet. The whole width is 44 feet, and ledges, balustrades, and semi- octagon recesses, or towers, with the well-paved footpath, give this bridge an elegant appearance. Blackfriars' Bridge, (see Plate, Bridges,) has elliptical arches, and no precaution was neglected that could contribute to its strength, or give addition to its elegance. In the middle arch, which is of 100 feet span, the flat part of the arch is described with a radius of about 57 feet; the lesser circles on either side being 35%, or 36 nearly. This small arch is con- tinued below its diameter, till its chord, as in the annexed figures, become 16 feet nearly, and its versed sine 5 feet nearly, which gives it the degree of novelty alluded to ; and which is far from being disagreeable to the eye. §-º-Twº- / § The shoulders are compactly filled - N with ruble work, the bed of each / § row tending to the centre of the º s \ arch. To the height to which the arch can be raised without a sup- Chord. porting frame, an inverted semi- º circle is drawn, the convexity of the arch resting upon this ruble work, which is formed of Kentish rag ; but other hard stone will equally well answer this purpose, as that cannot be every where procured. The in- verted arch answers two purposes; it prevents this ruble being raised by any lateral pressure, and makes those parts of the arch which form the greatest lateral pressure, abut upon each other; hence there is little or no lateral pressure upon the pier. The bridge of Burton-on-Trent is the longest in Britain, being 1545 feet, supported on 34 arches: the most stupendous in Europe, that over the Tave in Glamorganshire, consisting of only one arch, the segment of a circle whose diameter is 175 feet; the chord of the segment, or span of the arch, 140 feet, the height or vertical sine 35 feet; the abutments 32 feet: the architect was William Edward, a country mason: it was built in 1756. - - The Rialto at Venice, built by Michael Angelo, is reckoned a masterpiece of art, on account of its flatness and extent, being 98% feet span, and 23 feet only above the water; but this is far outdone by many bridges of modern erection. Wooden Bridges. Where stone bridges cannot be constructed, on account of expense, or other causes, very durable ones may be formed of wood: all the parts ought to press on one another like the arch of a stone bridge; and thus, instead of being Weakened by great weights passing over them, they will become the stronger. How this is to be effected, will be best under- stood from the annexed figure. Q 3 8 __iº BºsTMNNN - asſ SI ſ | S **. * B. R. I. B. R. I. dictionary of MECHANICAL SCIENCE. The Swiss Bridge, (as represented in the following figure,) a rude composition of trees unhewn, and covered with rushes or boards, serves very well for small streams, canals, &c. in º: º º: ºss º º Zººs º º Z/2Zººs gentlemen's parks, &c. This may be improved by the addition of a rustic balustrade, in the following style. The Tied-Plank Bridge, (as in the annexed figure,) is formed by fixing the ends of two or more planks in two heads of iron, a, a, and then connecting them by wrought iron rods, b, b, fixed SE to the heads in the manner of a bow string. A very slight bridge, thus formed, acts both by tenacity and gravity. Thus, when the bridge is butlightly loaded, the particles of the boards are not moved, but merely pressed on, and, therefore, the arched part may be said to act by gravity, while this pressure, being propagated to the abutments, these are held in equili- brium by the iron rods acting by their tenacity. On the other hand, when a bridge of this description is heavily loaded, the arch will bend downwards, or yield in some places, and rise in others; in which case the whole will act by tenacity. A very light and strong Bridge may be formed by screwing together thin boards in the form of a segment, or by screwing together a system of triangles of timber, as in the following figure. These triangles being equilateral, become in effect so many parts of hexagonal figures, which may be circumscribed by a circle, and thence carried to any extent, though, in the con- struction, the whole may act more by tenacity than by pressure. Light Bridge. For broad sluggish rivers, swampy ground, &c. such a bridge will do very well, but it is inferior perhaps to the following Strong Bridge. º The Boat Bridge, as here represented, may be worked by a mechanical power, as the wheel and pinion, or by means of a cylinder and rope B, and machinery fixed in a box C, and connected with the rope D, the vehicle may be moved from one side of a stream to the other, by merely turning the winch E. A contrivance of this kind was devised by Repton, for passing a piece of water in the park of Holkham Hall, Norfolk, the estate of T. W. Coke, Esq. The Flying Boat, as represented in the annexed figure, with the deck arranged as part of the gravel walk, which approaches s N the edge of the water, derives its - § motion from the obliquity of its - y - - sides to the direction of the cur- rent, which must be kept up by the use of a rudder. The force N of the stream is at a maximum º when the angle formed by it and N the side of the boat, is 54° 44'. \\ The boat a must be anchored to a post b, fixed in the middle of the river, and the longer the cable c, the manoeuvre will be the more easily executed, provided the move- ment is not made in a greater arc than 90°. The same purpose may be effected by a triangular raft, without the help of a rudder. The Flying Bridge may be formed of several, or indeed of many boats, joined together and floored with substantial planks, surrounded with a rail or balustrade; and according to its breadth it may have one mast, or two masts, to support a rope at a proper height; one end may turn round a windlass, the other may be fastened to an anchor in mid stream, and may be kept aloft by buoys. As in the former case, the bridge is worked by one rudder, if there is one boat; if more boats, then 2 K. 126 B R I B R I DICTIONARY OF MECHANICAL SCIENCE. each may have a rudder; the tillers of all the rudders moving at the same angle. As the stream is narrow or wide, the sus- pension rope may be shortened or lengthened by the windlass. Such bridges will ferry over cavalry or infantry; but to become defensible by mutual support and augmented strength, several such bridges, at convenient distances, are launched and moored. A B, CD, (in the following figure,) are two long boats which support the bridge; G H, K L, two masts joined |C | º at their tops by traverse beams, and a central arch supported in a vertical position, by two pair of shrouds and two chains, L N and H. R. M is a horse, or cross piece, upon which the cable MF, ef, rests: the use of this has been explained above. The buoys are e,f. E. windlass, a, b, rudders. A B, CD, two portions of bridges of boats fastened to the banks on each side of the stream, and between which the bridge traverses. The annexed figure is a ground plan of the same bridge. K, Q, >º-> G Cl the mast holes; E, windlass; N, N, pumps; P, P, capstans. Fig. 1, a lateral elevation of the same; b, the rudder; E, the View Fore and Aft. I p >= | 9 Ay 2 k M . K Q =|[=|E|HE-H windlass; M, the horse; E, N, H, F, the cable. Fig. 2, is an elevation of the hinder part of the bridge or stern; a, b, the two boats; Q H, KL, the two masts; HL, the upper traverse beam; p q, the lower traverse beam, over which the cable passes, and occasionally slides from one mast to the other; and must on that account be kept well greased. pk, 9 g, shrouds; M the cross piece over which the cable passes to the windlass. - * The Bushen Bridge, made of bundles of rushes, serves to afford a passage over marshy ground. And bridges of casks, bottles, bladders, and buoys made of skins, do well for trans- porting individuals, or even troops, as portable machines. The Draw Bridge, made after the manner of a float, to draw up or let down, as occasions serve, before the gate of a town or castle, may be made after several different ways; but the most common are made with plyers twice the length of the gate, and a foot diameter. The inner space is traversed with a cross, which serves for a counterpoise, and the chains which hang from the extremities of the plyers, to lift up or let down the bridge, are of iron or brass. Such bridges we have seen at Stirling and Edinburgh castles, at the Tower of London, at the castle of Vincennes, and many other regularly fortified places. In navigable rivers it is sometimes necessary to make the mid- dle arch of bridges with two moveable platforms, to be raised occasionally, in order to let the masts and rigging of ships pass through this kind of drawbridge. A B (in the following figure) represents the middle of the arch ; AL and B L the two piers that support the drawbridge, N O, one of the platforms of which is raised and the other let down, having the beam PQ e P P P for its plyer. To N O are suspended two moveabe braces, EH, E H, which resting on the support E, press against the bracket M, and thereby strengthen the draw bridge. These braces are conducted to the rest by mcans of the weight S pulling the chain S L F. It will now be necessary to proceed with those details upon which the practical construction of bridges depends; and we will therefore lay down Belidor's Table for the thickness of their piers, agreeably to what has been said above, on the rela- tive proportions between the span of the arch and the thickness and height of the piers. . - The first horizontal line expresses the height of the piers in feet, from 6 to 24 feet, each increasing by 3. The first vertical column, the width of the arches from 20 to 100 feet, for every five feet. The other columns express the thickness of piers in feet and decimals, according to the respective height at the head of the columns, and the width of the arch against it in the first column. Thus, e.g. let the width of the arch be 60 feet, and the height of the piers 12, then the number 12-718 under 12, and against 60, expresses the thickness of the piers, i. e. 12 feet 8 inches #ths. The length of the key-stone in an arch % ºfeet wide, is 2 feet; 3, 4, 5, 6 feet in an arch of 45, 60, 9 * v- s As this table contains the thickness of the piers in respect to arches that are commonly used in practice, we imagine it would be needless to carry on the table further; because the difference between the thickness of the piers of any two con- B R I B R I 127 DICTIONARY OF MECHANICAL SCIENCE. tiguous arches being but small, those between any two marked here may be made equal to half the sum of the next below and above it; thus, the thickness of the piers of an arch 62 or 53 feet wide, is nearly equal to 10:242, half the sum of the thick- nesses 9-085 and 10-64, of the arches 50 and 65 feet wide, when the height of the piers is 6 feet. TABLE containing the Thickness of Piers of Bridges. 6 || 9 || 12 | 15 | 18 21 24 20 || 4°574| 4°918| 6′165| 5'350 5'492|| 5'610| 5'689 25 5.490. 5'913| 6’216 6.455) 6645 6.801 7.980 30 | 6′386; 6-816| 7-225| 7:513| 7-746|| 7-939| 8-102 35 | 7258 7.78s 8:200 8532, 8.807. 9037 9.238 40 sºoq sepil 9-14s 9,523. 9835lio oil 10:32s 45 | 8965, 9:579/10077|10:489/10.817|11:316|11394 | Go || 0:80810.464,0987|11435 rs17|13148|12234 55 10-640|11-245) 11°882] 12-364) 13:019||13-149||13°218 60 |11,400||12:110|12718|13218|13723|14-109) 14:314 65 12°265 13-025] 13-648||14-185| 14-654|| 15:082] 15:435 70 || 13'114|| 13.869|| 14:517|15-049 15'573| 16.01 || 16:400 75 || 14'000 || 14.705] 15:336||15'965 || 6’480|16:940 || 7-354 80 || 14-747 | 15'542|16°234|16'842|| 17'381 17.864| 18-296 85 | 15:513| 16.328||17-041 || 17-674|18:237|18-742; 19. 198 90 | 16.373 17, 201|17°4′29||18-178| 19°257 | 19.679|20-132 95 || 17-184| 17-826||18°771 || 19.438|20-036|20°577|21:008 100 || 17-991 | 18-848|19:620 |20°293 |20-908|21'468|21.978 Rectangular piers are seldom used but in bridges over small rivers. In all other cases, they project beyond the bridge by a triangular prism, which presents an edge or an angle to the cur- rent, in order to divide the water more easily, and to prevent ice and other matters, that float, from sheltering there, as well as vessels from running foul against them. That edge is ter- minated by the adjacent faces at right angles to each other at Westminster bridge, and makes an acute angle at the Pont Royal of Paris, of about 60 degrees; but of late, the French terminate this angle by two cylindric surfaces, whose bases are arcs of 60° in all their new bridges. Slope of the Bridge on each side, and Width.-When the banks of the rivers are high, the bridge is level above, and all the arches of an equal width; but where they are low, or for the sake of navigation, a large arch is made in the middle of the stream, and the bridge is higher in the middle than at the ends; the slope easy and gradual on both sides, so as to form one continued curve line. The descent of that slope may be one- fiftieth part of the length. The width allowed to small bridges is 30 feet; but in large ones, near great towns, 30 feet are allowed clear for horses and carriages, besides a pathway on each side for foot passen- gers, from 6 to 9 feet broad, raised about a foot above the car- riage road; the parapet walls on each side are about 18 inches thick, and 4 feet high, and generally project over the bridge with a cornice underneath. Sometimes balustrades of stone or iron are placed upon the parapet, as at Westminster and Blackfriars' bridges; but this is only practised in bridges of a great length, and near the capital of a country. bridges, open from the middle of the two large arches with two The ends of wings, making an angle of 45 degrees with the vest, in order to make their entrance more free and easy. These wings are supported by the same arches of the bridge next to them, being continued in the manner of an arch, of which one pier is much longer than the other. .. The Methods of Laying the Foundation.—Laying the founda- tion of the pier is the most difficult part of the whole work, except when the depth of the water does not exceed 6 or 8 feet. In shallow water, one of the abutments, with the adja- cent piers, is enclosed by a dike of a sufficient width for the work, and room for the workmen. This dam is made by driv- ing a double row of piles, whose distance is equal to the depth of water, and the piles in each row are 3 feet from each other. They are fastened together on the outside by bonds of 6 by 4 inches thick. This done, frames about 9 feet wide are placed on the inside, to receive the boards which are to form the enclosure. The two uprights of these frames are two boards of an inch and a half thick, sharpened below, to be driven into the ground as deep as necessary; then the boards themselves are likewise driven in till they reach the firm ground under- neath. Between every two piles, tie-beams are fixed to the ends of the piles, to strengthen the inside wall, and fasten it to the outside one; these tie-beams are let into the bonds, and bolted to the adjacent piles. The bottom is then cleared from the loose sand and gravel, by a machine like that used by ballast-heavers, and then well prepared clay is rammed into this coffer very tight and firm, to prevent the water from oozing through. Sometimes these enclosures are made with piles only, driven close to each other; at others, the piles are notched or dove-tailed one into the other; but the most usual method is to drive piles with grooves in them, 5 or 6 feet distant from each other, and boards are let down between them in these grooves. & Pumps and other engines are now used to draw the water out of the dams or enclosures, till they become quite dry; them the foundation is dug, and the stones are laid with the usual precautions, observing to keep some of the engines always standing, to draw off the water that may ooze through the coffer work. The foundation being cleared, a course of stone is laid on the outside all round, with the largest stretchers and headers that can be had, and the inside filled with ashlers well jointed, the whole laid in terrass mortar; and some cramps are also used to fasten the facings with the inside. The same manner is to be observed throughout all the courses, to the height of low water mark; after which, the facings alone are laid in terrass mortar, and the inside with the best of the com- mon sort. When the foundation has been raised to the height of low-water mark, or to the height where the arches begin, then the shaft or middle wall is to be carried up nearly to the height of the arches, and there left standing till all the piers are finished, in order that the masonry may be sufficiently dry and settled before the arches are begun. The proper Form of the Base.-As the piers end generally with an arch at each end, it is usual to lay the foundation in the same manner; which is not so well as to continue the base rectangular quite to the ends of the piers, and as high as low- water mark, both because the foundation becomes then so much broader, and also because the water will not be able to get under it; for when the current sets against a flat surface, it drives the sand and mud against it, so as to cover it entirely, whereas if a sharp edge be presented to the stream, it carries every thing away, and exposes the foundation to the continual action of the water, which in course of time must destroy it. After the intervals between the arches are filled up with. stones, laid in a regular manner, without mortar, and the gravel is laid over them; two drains or gutters are made Iengthwise over the bridge, one on each side next to the foot- path, about six feet wide and a foot deep, which being filled with small pebble-stones, serve to carry off the rain water that falls on the bridge, and to prevent its filtering through the joints of the arches, as often happens. g Method of Building with Coffers, as was practised at West- minster Bridge, is to build with coffers, when it is preferable, from the depth of water being 6 feet at a medium when lowest, and the tide rises about 10 feet at a medium also, so that the greatest depth of water is about 16 feet. At the place where B R. I B R. I DICTIONARY OF MECHANICAL SCIENCE. #. one of the piers at the middle or great arch was to be, the workmen drove piles of about 13 or 14 inches Square, and 34 feet long, shod with iron, so as to enter into the gravel with more ease, and hooped above, to prevent their splitting in driving them home. These piles were driven from 13 to 14 feet below the bed of the river, and 7 feet distant from each other, parallel to the short ends of the pier, and about 30 feet distant from them. The number of these piles was 34, and their intent was, to prevent any vessels or barges from ap- proaching the work; and in order to hinder boats from passing between them, booms were placed so as to rise and fall with the water. At this stage of the work, the ballast-men dug the foundation under the water, of about 6 feet deep, and 5 wider all round than the intended coſfer was to be, with an easy slope, to prevent the ground from falling in. In order to prevent the current from washing the sand into the pit, short grooved piles were driven before the two ends, and part of the sides, about 4 feet higher than low-water mark, and 15 feet distant from the coffer: between these piles, rows of boards were let into the grooves down to the bed of the river, and fixed there. The bottom of the coffer was made of a strong grating, con- sisting of two rows of large timbers, the one longways, and the other crossways, bolted together with wooden trunnels ten feet wider than the intended foundation. The sides of the coffer were made with fir timbers laid horizontally close one over another, pinned with oaken trunnels, and framed together at the corners, excepting at the two protruding angles, where they were secured with iron, so that the one half might be loosened from the other; if it should be thought necessary : these sides were lined on the inside, as well as, on the outside, with three-inch planks placed vertically; the thickness of those sides was 18 inches at the bottom, reduced to 15 above, and they were 16 feet high; besides, knee-timbers were bolted at the angles, to secure them in the strongest manner. The sides were fastened to the bottom by 28 pieces of timber on the out- side, and 18 within, called straps, about 8 inches broad and 3 or 4 inches thick, reaching and lapping over the ends of the sides. The lower part of these straps had one side cut dove-tail fashion, to fit mortises made near the edge of the bottom, and were kept in their places by iron wedges; which being driven out when the sides were taken away, gave liberty to clear the straps from the mortises. - Before the coffer was launched, the foundation was ex- amined, to know whether it was level; for which purpose several gauges were made, each of which consisted of a stone of about 15 inches square and 3 thick, with a wooden pole in the middle, of about 18 feet long. The foundation being levelled, and the coffer fixed directly over the place with cables fastened to the adjacent piles, the masons laid the first course of stones for the foundation within it; which being finished, a sluice made near the side was opened at low water, on which the coffer sunk to the bottom ; and if it did not set level, the sluice was shut, and the water pumped out, so as to make it float till the foundation was levelled: then the masons cramped the stones of the first course, and laid a second, which being likewise cramped, a third course was laid: then the sluice being opened again, proper care was taken that the coffer should settle in its due place. The stone work being thus raised to within two feet of the common low-water mark, abóut two hours before low water the sluice was shut, and the water pumped out, so far as that the masons could lay the next course of stone, which they continued to do, till the water was risen so high as to make it unsafe to proceed any further ; then they left off the work, and opened the sluice to let in the water. Thus they continued to work night and day, at low water, till they had carried their work some feet higher than the low-water mark; after this, the sides of the coffer were loosened from the bottom, which made them float, and then were carried ashore to be fixed to another bottom, in order to serve for another pier. It must be observed, that the coffer being no higher than 16 feet, which is equal to the greatest depth of water, and the foundation being 6 feet under the bed. of the river, the coffer was therefore 6 feet under water when the tide was in; but being loaded with three courses of stones, and well secured with ropes fastened to the piles, it could not move from its place. By making it no higher, much labour and expense were saved; yet it answered the intent fully as well as if it had been high enough to reach above the highest flood. - t ** The pier being thus carried on above low-water mark, the masons finished the rest of it during the intervals of the tides in the usual way; and after all the piers and abutments were finished in like manner, the arches were begun and completed as mentioned before. The whole bridge was built in about seven years, without any accidents happening either in the work, or to the workmen. Materials employed.—All the piers were built with solid Portland stone, some of which weighed four tons. The arch stones were likewise of the same sort; but the rest of the masonry was finished with Kentish rag-stones, and the paths for foot passengers were paved with Purbec, which is the hardest stone to be had in England, except granite, called otherwise Plymouth marble. This Method sometimes impracticable.—This method cannot be used in many cases; as where the foundation is so bad as not to be depended upon without being piled, or the depth of water is very great, with a strong current and no tide. For if piles are used, it will be impossible to cut them off in the same level five or six feet below the bed of the river; and if this is not done, the grating or bottom of the coffer will not be equally supported, whereby the foundation becomes precarious. In a great depth of water, having a strong current and no tide, the coffer must reach above the water, which makes this process expensive, unwieldy, and difficult of execution; so that there is no probability of using it in such a case. The Russian Method.—In some cases, where there is great depth of water, and the bed of the river tolerably Ievel, or where it can be made so by any contrivance, a strong frame of timber, four times as large as the base of the piers, may be let down with stones upon it, round the edges, to make it sink. After fixing it level, piles must be driven about it to keep it in its place, and the foundation laid in coffers as before, which are kept steady by ropes tied to the piles. This method has frequently been practised in Russia; and though the bed of the river is not solid, yet such a grating, when once settled with the weight of the pier upon it, will be as firm as if piles had been driven under the foundation; but to prevent the water from gulling under the foundation, and to secure it against all accidents, a row of dove-tail piles must be driven quite round the grating. This precaution being taken, the foundation will be as secure as any that can be made. The French Method.—The French engineers use another method in raising the foundations of masonry under water, which is, to drive a row of piles round the intended place, nearer to, or farther from, each other, according as the water is more deep or shallow. These piles being strongly bound together in several places with horizontal tie-beams, support a row of dove-tail piles driven within them : when this is done, and all are screwed according to the nature of the situation and circumstances, the foundation is dug by a machine with scoops, invented for that purpose, until the workmen come to a solid bed of gravel or clay; or if the bed of the river is of a soft consistence to a great depth, it is dug about six feet, and a grating of timber is laid upon it, which is well screwed with piles driven into the opposite corners of each square. When the foundation is thus prepared, the masons make a mortar called beton, which consists of twelve parts of pozolano or Dutch terras, six of good sand, nine of unslaked lime, thir- teen of stone splinters not exceeding the bigness of an egg, and three parts of tile dust, or cinders, or else scales of forge iron: this being well worked together, must stand 24 hours, or till it becomes so hard as not to be separated without a pick- axe. This mortar being thus prepared, they throw into the coſfer a bed of ruble stones, not very large, and spread them all over the bottom as nearly level as they can; they then sink a box full of this hard mortar broken into pieces, till it comes within a little of the bottom ; the box is so contrived as to be overset or turned upside down at any depth; the pieces of mortar now soften, and so fill up the vacant spaces between the stones; by these means they sink as much of it as will form a bed of about 12 inches deep. all over; then they throw in B R I B R I 129 DICTIONARY OF MECHANICAL SCIENCE. another bed of stone, and continue alternately to throw one of mortar and one of stone, till the work approaches the surface of the water, where it is levelled, and then the rest is finished with stones in the usual manner. A coffer containing 27 cubic feet of masonry made of this mortar, and sunk into the sea, was there left standing for two months, and when it was taken out again, it was harder than the stone itself. - The usual way in which the foundations of Waterloo Bridge, Southwark Bridge, and Vauxhall Bridge, have been laid, was by driving piles of Memel logs, 14 or 15 inches square, for the construction of the coffer, which was cleared of water by means of pumps, and the work proceeded much in the same way as mentioned above. GeoMETRICAL Construction of Bridges.—Bridges constructed with circular or elliptical arches, being the most common, we now proceed to lay down a theory for their construction, founded on philosophical principles, which, by our mode of explanation, will be understood by the mechanic, and cannot be unworthy the attention of the man of science. All bodies in the earth tend to the centre of the globe, unless prevented by some force that resists their obedience to the universal law of gravity, and changes their direction. If we attend particularly to one body, having all its parts tending equally to the centre of the earth, and supported in that posi- tion, it will retain its position. If we suppose another body to press upon it, so as to change that position, which it has on its support, or force away its support, in whole, or in such part, that a greater part of the body has a tendency to the centre, more than it has to its support, it will fall towards the earth in a direction to its centre. Let A B, as in the annexed figure, be two supports, suppose one foot square, 5 feet high, or any other height, standing Egyptian Bridge. JD `S D | \ | | | H T |- | -| # | - A B. |- perpendicularly, and let a piece of the same dimensions, wood or stone, F, three feet in length, be placed across in equilibrio; the perpendicular support is not pressed by this weight, but in the perpendicular direction. If a second piece, of 5 feet, is laid upon the 3 feet piece, in the same way, projecting 1 foot on each side, they will still remain in equilibrio, and so on till the two bodies upon the two uprights meet one another, as in the figure, the planks or logs D D meet in E, without affecting the supports, except in the perpendicular direction. . The equilibrium being preserved, no force imposed will make the supports give way, that will not separate the particles of mat- ter, or break its contexture. Neither will any weight push it over, that is not greater than the perpendicular pressure; for action and reaction are equal, acting in contrary directions. The force then that it will support before it yield, is equal to the number of square feet that rests on its surface, and turns upon the angular point F. Now, suppose.this operation con- tinued the whole length of the bridge, and the whole level blocks in contact with one another, received by the abutments, or landstools, the bridge will support any weight that the strength of those blocks could sustain, and the abutments react upon. This is the genuine Egyptian arch, not elegant, but strong, as each block is supported one foot distant, and the upper ones in contact with one another, only react by their own strength, at one foot distant, without support; and by the reaction of the land abutments cannot yield to give any lateral pressure upon the pier. Let us now suppose a semicircle of any other arch described, the superfluous matter is carried off, and the arch remains in strength and beauty. Now, instead of balancing the blocks by counterpoise on each side of the support, let this be taken off, and applied as weights above the pier, being equal in weight to those that form the arch, the equilibrium is still preserved, without any lateral pressure. This may be illustrated by a very simple experiment. Let A, B, C, D, in the annexed figure, be four blocks; the first, A, a square, which re- presents the base; if the second, B, a pentagon, inscribed in a circle of the same radius about which the square is described, be placed with one of its angles to the perpendicular edge of the square, a perpendicular falls within the base, and T} it is therefore firmly supported. Let the hexa- gon, C, be placed upon one of the sides of the A. pentagon, the two angles likewise coinciding. In this the perpendicular falls over the base; it will therefore be no longer firmly supported, but will fall, and, if attached to the pentagon, would carry a part of it along with it, except prevented by friction, and consistency of the texture of materials. In this situation let it be retained, till a pentagon is placed on the opposite side of the hexagon; the plumb line, or perpendicular, as it now appears, falls within the base, and will be again supported so as to carry an additional block raised upon it, or require a considerable force to pull it over on that side, to which the hexagon was inclined to fall. The conclusion we would draw from the above, is, that if the column or pier is of such dimensions at top, where the spring of the arch rises, that a weight of such materials as the arch is composed of can be raised, not exceeding the height of the vertex or crown of the arch, as will counterpoise that part of the arch that produces the lateral pressure; then a pier of such dimensions is of sufficient strength to support such an arch, till the other arches are thrown, and the whole made to abut upon columns that will counterpoise the whole with any incumbent weight proposed. To apply the arches to their piers, and to one another, they should abut upon one another, as in the following figure. . I) In the next figure, we take a semicircular arch of 75 feet span, or archstone we think of a sufficient strength, at 3 feet length; our pier 6 feet, equal to the two archstones. As every arch can be raised to a certain height, without the support of the centre arch ; allowed, to the 30th degree, or one-third of the distance to the crown of the arch, we have divided the quadrant or half of the arch into eighty-three equal parts; and where more than half of the archstone falls over the per- pendicular, we consider this as the height, not to be exceeded without support. The weight of matter upon the pier to this height, we compare with the weight of matter from that con- tained in the archstones, or rather, what breadth of pier will contain a quantity of matter that will counterpoise the weight of the archstones of an arch of given span, and length of arch- stones to the crown of the arch. In investigations of this kind, recourse is had to trigonometrical calculations, and to algebraic and fluxionary equations. Foreign writers give us rules, col- lected from such constructions as suited their faste; and most algebraic and fluxionary equations take their data from some bridge, the construction of which pleases the writer, and brings his result agreeable thereto. . . . . . . | Let us consider the archstones as wedges abutting upon one 2 L T30. B R I B R. I DICTIONARY OF MECHANICAL SCIENCE. another, and the whole upon the landstool, or upon the pier of the particular arch, and resisted by pressure, which may be expressed by a line placed at right angles to an archstone, at that part of the arch which rests upon the centre arch; but whose length is not yet determined, but will be determined in the result of our theory, of which every mechanic is able to judge; and which, at the same time, we flatter ourselves the learned will not find cause to challenge. Jier, - *7:\]]|| ~f~ +e−E’ The thickness of the pier we have taken is, Ab, 6 feet; each division of the arch is equal to 2 feet on the outside, and tends as a wedge to the centre of the circle. The inside measures 1-8 feet, the mean is 1.9 x 3; the length of the stone is 5’7 of surface : we suppose it taken 3 feet into the arch, or it is equal to 17°l solid feet in each of our divisions; the scale is half an inch to 10 feet. The solid measure on the whole is easily found; the 30° is at a, but the arch will rise without the support of the centre arch to c. Now, the number of divisions from a to the centre of the arch, is 22:2; which multiplied by 17:1 solid feet each, is 379-62 solid feet; the pier of 6 feet contains to the height, a, the surface A b d a, at a mean, taken as in the table, a is 72-75, being each 2 feet, is 145.5 superficial feet, x 3, the assumed depth is 436-5 solid feet, being fully in equilibrium with the archstones; but as the arch will rise to c, there is an additional weight of 229-5 solid feet, which will be allowed more than a counterpoise to the pressure of the arch, without any aid from the pier, which has only the perpendicular pres- sure to support. By this, therefore, is ascertained, the coun- terpoise which will support this arch until the other arches are raised ; which, as they all abut upon one another, the land- stool must be made of such strength as to counterpoise the whole. This is ascertained upon the same principle, and leaves no stress upon the piers, but the perpendicular pressure alone. This pier is scarce one-twelfth part of the opening, by which, the river having so free a passage, will affect the bridge by pressure but very little. The above figure is a perspective view of one arch of a bridge, on this construction, with part of an adjoining arch on each side. But the piers must be made of greater breadth, when the situation of the river, or other circumstances, or when a seg- ment of a circle is made choice of for the ease of the passage, or when economy in the use of materials and mason-work are considered ; or the base of the arch, or the surface of the pier, will not admit of mason-work to bear upon the spring of the arch, of such weight as to produce a sufficient counterpoise to the archstones that produce the lateral pressure. If the arch is flatter than that now under consideration, the pier ought to be broader; and this is ascertained in projecting the plan. At the same time, as the fall and destruction of an arch is attended with very great loss in money, time, and materials, by way of precaution, beams may be made to abut upon one another, and upon each pier; and this will be no loss of time or materials either, as it will supply, in part, the support of the centre arches, upon which the arch of the bridge is raised ; and it is a precaution used, upon a smaller scale, when, in front walls of houses, the whole is often supported upon arcades of shop doors and windows, many of their piers not ex- ceeding 9 or 10 inches: a cross bar, or piece of wood laid across, to prevent their yielding or losing the perpendicular, till the whole is completed. Now, the pressure upon the arch is not so great as most writers have assigned, that is, to the whole incumbent weight of all the materials above it, together with that of passage. The art of masonry is such, that the beds or rows of stones are so bound one with another, that each makes a pressure on its contiguous part, so as to form an arch of themselves. We see in well-built walls a vast excava- tion made in the lower part, or in the middle of the wall, and the upper part of the building not affected. In like manner, the arches being all raised to the height that they can be, without the support of the centre arch, they are completed and filled up to the level of the keystone, but not higher. The arch is properly secured, if the principles of equilibration, in filling up, are properly attended to ; but if one side is over- loaded, either in filling up or in building, it must twist the arch, and, if not instantly to break it, must tend to an uncer- tainty as to its durability. Among the various writers upon bridges, some prefer the circular arch, both for strength and elegance. Others contend, that it is exceeded in both by the elliptic arch. Others will give the preference to the eatenarian arch ; and we are told, that the excellency lies on the side of the parabolic curve. We do not think it incumbent on us to combat each of these ; neither do we think our readers would thank us for so doing. It may, however, be expected, that we should not pass them entirely unnoticed. º In the first place, then, we are of opinion, that the arch that bears most equally throughout the whole, one part upon another, has the best claim to strength. Our reason is, which we illustrate thus, let A B, A C, be placed as in the annexed figure. Suppose a weight, placed upon them in such a manner as A. to press equally upon the point A, the two bodies A B, A C, will in that point support the great- est weight. If the same weight is laid in the middle, between A and C, or A and B, they will each yield to the pressure; for the weight is not equally di- vided between them. But if these bodies are so placed, that in every position on which a B, ° weight can be applied to them, the weight shall. be equally sup- ported by both, we should give this form the preference as to strength; and this is the case with the circle. As to elegance, we know that regularity is a qualification that suits every taste; and here the circle cannot be outvied. It is not, how- ever, without its disadvantages; for with regard to expediency, the semicircular arch is sometimes too high for the situation of some bridges. In this case, the elliptic arch, formed upon the greater axis, offers itself, in point of expediency, and yields not in point of elegance. We are bold enough to assert, that if strength of materials forms its composition, and be properly abutted, it will not yield, in point of strength, in any exigence to which it may be applied. In point of economy, it claims a preference to the semicircular arch. - For our part, we are inclined to own the reasonableness of its claim, and to give it the preference to the segment of a circle, which might perhaps be preferred in point of expedi- ency, as it can be rendered as flat as the ellipse; but its flat- ness we rather consider as a disadvantage, as in the rise of the water it is apt to choke its course, and overturn it; whereas, the ellipse being nearly formed of two segments of circles of different radii, the smaller arches at its extremity raise more in the perpendicular, and give more scope to the current of the water; and likewise, it does not require a stronger pier than a semicircle of the same diameter. The segment, on the other hand, if flat, requires a stronger pier, and therefore tends more to choke the current of the river, which ought always to be avoided when it can be done. In the catenarian arch, when a chain or rope is fixed at each end, and allowed to fall down in the middle, the curvature is not equal throughout; and we therefore cannot think it entitled to equal claim with the circle or ellipse. The same objection may, with equal propriety, be made to the parabola. This curve, near its vertex, has almost the property of a circle; but every one who knows a parabola, is convinced how much it deviates from it afterwards, although every where it retains the property of its own curve. B R. I |B R. I 131 DICTIONARY OF MI2C HANICAL SCIENCE. We now take a review of the different bridges we have men- tioned, and make some observations upon them. In general, we remark, that all the writers upon this art have formed the abutments of each particular arch, to be placed in the pier below the spring of the arch; on which account, many have constructed their piers of greater strength than necessary; as in that by the Roman emperor Trajan, over the Danube; but being broken down by his successor, to impede the passage of his invaders, we cannot, with certainty, compute the lateral pressure upon the piers. - According to the rules given by Belidor, the breadth of the pier that will form an abutment to an arch of 75 feet span, is 14 feet, if the height at the head of the columns be 6 feet. We have formerly stated, that this arch can be raised to c, as in the following figure, without applying the centre arch. From the centre of this archstone we raised a perpendicular p g, and from the lower part of the archstone drew the line f b, parallel to it: this line, f b, we supposed to cut the centre of the pier in h. Suppose Belidor allowed a part of the pier equal to the length of the archstone, which we have in this figure taken at 3 feet, one-twenty-fourth of the opening nearly, viz. h b, Ah, would be allowed for the perpendicular support of the archstones to c. We find h g measures five and a half feet, we therefore extend h g to l, which is 11 feet, and Al 14 feet, for the breadth of the piers. In place of taking the whole width of the bridge, we take only 3 feet, as formerly. The number of equal divisions from c to the vertex, or middle of the keystone, is 20; ; each of the equal divisions at these breadths contains 17.1 solid feet; as by our former measure, which multiplied by 20%, is 350-55 solid feet. The pier, 14 feet broad by 6 in height, and 3 feet deep, is 252 solid feet; the solid building, cfb m, being supported in the perpendicular, he considers as a part of his abutment, of which f b measures 26 feet, by c.f3, and by 3 in depth, is 234 + 252 = 486 solid feet, to counter- poise 350:55 solid feet, which is amply sufficient. Suppose that the pier is 13 feet, at the above height it contains 234 feet, + 234 as before, E 468 feet, which, to account for accidents, and from his practice and observation, gives the dimensions of the table rule, which, we suppose, is now fully accounted for. If the height of the pier is more than 6 feet, we add to the breadth of his pier in proportion. When the span is above 80 feet, one-sixth of the opening is sufficient in strength to resist every exigence ; but if the arch is a segment, the same rule gives the breadth of the pier rather more than 14 feet. Belidor confines his rule to the semicircular arches. We have already mentioned what we think a proper limitation to his rule for taking the 24th part of the arch for the length of his archstone. London Old Bridge, executed in stone, under the direction of Peter Colechurch, a priest; was thirty-three years in building, being begun by Henry II. in 1176, and finished by John in 1209. The piers, eighteen in number, are from 25 to 34 feet thick. Peter turned the course of the Thames through South- wark, while he executed an undertaking that choked tºp the course of the river, from 900 to 194 feet; but as this objection is about to be removed, we need say no more about it. Westminster Bridge, an elegant and noble fabric, has its pier only 8 feet from the bed of the river. The thickness, for a suffi- cient counterpoise to the arch, could not exceed 14 feet; but lately, the architect has given it 17. The arches are semicircu- lar, the middle one being 76 feet span; the ascent one-twen- tieth part of the half-width of the river, which is here 1223 feet, one half is 621'15, and the rise is 30% feet in that extent. The next we notice, is Blackfriar's, as in the following figure, executed by Mylne, whose ingenuity and ability as an engi- neer are universally acknowledged. The middle arch is an elliptic span of 100 feet, by which, with other advantages, the passage is rendered more commodious; the ascent more easy than on Westminster Bridge. The quickness of the rise of the arches of the small circles, with the flatness of the large circle, are particularly well adapted to give a more easy passage to the river, when rising either from a tide or other accidental causes, and renders the choice of the elliptic arch here very judi- cious. We are likewise much pleased with the ingenuity of the inverted arch, which effectually prevents any rising of the ruble work that fills the interstices between the arches by any pressure whatever; as it abuts upon the archstones at E, it presses their joints upon one another, in a more effectual man- ner than perhaps could be accomplished by any other method; but the effect produced by it, and in which we think its excel- lency mostly consists, is, that it makes the arches, at that point where they produce the greatest lateral pressure, to abut upon one anqther, and thus take off the lateral pressure from the pier. Had Mylne availed himself of this, his pier would have been at least one half thinner. But in place of this, he has made it at the extremity of the greater axis, A a, B b, 19 feet, and increased it in a circular form to 22 feet. Experience has proved, that when the resisting force is placed in the pier, one- fifth of the opening is more than sufficient for supporting this resisting force; therefore the course of the river should not have been contracted from 100 to 70 feet. - The depth of the water, at ordinary tides, is not less than 16 feet; and by the principles of hydrostatics, the pressing force of a solid foot of water, at that depth, is equal to 8500 lbs. which x 30, the number of feet contracted, gives 113-8 tons upon the foundation of his pier, far more than was necessary; but this does not at all derogate from the method. In our drawing of the middle arch, and part of the adjoin- ing arches, A B is the length of the greater axis of the ellipse, and span of the arch 100 feet; f, f, the centres of the lesser cir- cles; D D, the inverted arches abutting upon the archstones E. E.; V, the vertex or crown of the arch ; F F, the thickness of the pier at the bed of the river; A a, B b, the thickness of the pier at the extremity of the greater axis. We have put on the bolting in one of the arches, one with the Kentish rag-stone; the bolts about a cubical foot, sunk half way into each stone; the stones in the pier are bolted with firm oak, of a solid foot, dove-tailed into each stone, which renders the whole pier firm as if one stone. What has been said on the breadth of piers, renders any observations on the bridge over the Trent at Burton, or the single arch over the Tave, in Glamorganshire, unnecessary; the abutments of the last being on land, the method of obtaining their strength will be pointed out when we speak of the abut- ments of iron bridges, of which there are now several in England. - - The first was that erected over the Severn, near Coalbrook- dale, in Shropshire, by Abraham Darley; the iron work was cast at Coalbrookdale in 1779, and consists of one arch of 100 feet 6 inches span. It rises to the height of 45 feet, and con- sists of ribs, each cast in two pieces, secured at the crown by a cast iron keyplate, and connected horizontally and vertically B. R. I B R I DICTIONARY OF MECHANICAL SCIENCE, by cast iron braces formed with dove-tails and forelocks; the ribs are covered with cast iron plates ; the railing is of iron : the weight of the whole is 3873 tons. The ironwork was exe- cuted by Messrs. Wilkinson and Darley, ironmasters; for which they have great credit, being the first instance of that material applied in the bridge way. In 1801 it appeared as perfect as when put up, except what was owing to the failure in the stone abutments, which had occasioned some cracks in some of the small pieces. The second bridge of this kind, built over the same river at Builtwas, at the expense of the county of Salop, was agreeably to a plan under the direction of Mr. Telford, surveyor of the ublic works in that county: the iron work was cast at Coal- rookdale in 1795 and 1796. It consists of an arch of 130 feet span; the rise of the arch is 27 feet from the spring to the suffit. The situation of the road here is necessary to be kept low ; and the outside ribs rise as high as the tops of the rail- ing, and are connected with the ribs that bear the covering plates, by bars of iron cast with deep stanches close to each other, and forming an arch of themselves; so that the bridge is made, upon the whole, compact and firm: the weight of the whole is 173 tons 183 cwt. Some smaller arches, and an aque- duct at Longdon, have been made under Mr. Telford's direc- tion in the same county. The next, upon a large scale, and made of iron, is that over the river Wear, at Monk-Wearmouth, in the county of Dur- ham. . This bridge, as represented in the following figure, is the segment of a circle, whose radius is 443 or 444 feet; the span of the arch, or length of the bridge, is 236 feet; the height of its vertex above the spring of the arch is 34 feet; and height above the surface of the water 60 feet; so that vessels of con- siderable burden may pass below it without interruption. The width of the bridge, or breadth of the roadway, is 32 feet: it is * * :- - gººm-- 4- - =T Twº- E" f & A. formed of six ribs, placed above five feet distant from one another; each rib consists of 125 blocks of cast iron, five feet in height, and two feet broad at the middle. The lines drawn from this to the centre of the curvature, determine the length of the block above and below; and a circle described with the radius of curvature, gives the convexity of the upper part of the block, and the concavity in the lower, agreeable to the curvature of the whole arch of the bridge. In each of the three longitudinary parts of the block, there is a Square groove one inch deep, into which is fitted a bar of wrought iron of the same dimension with the groove; and by this means the blocks are joined together to form the ribs. These ribs are connected laterally by a hollow bar of cast iron, about 4 inches diameter, and 5 feet long, with flanches through which iron bolts are made to pass it, and the sides of the ribs fixed with screws or forelocks; two of the blocks are joined by the bars of wrought iron, and connected with a bar of another rib, by the iron hollow bar. All the ribs joined together, and connected in the same manner, to complete the arch of the bridge. To support the beams that form the roadway, circular pieces are formed of cast iron, to abut upon one another at their horizontal diameter, the beams that form the roadway resting upon the circular pieces at the vertical diameter, which gives a firmness to these supports, that no weight coming upon the bridge can injure. The beams or planks are then covered with plates of iron, and such materials as are best adapted to ; the road, and prevent water passing through to injure the ridge. We have only to add, that this bridge was constructed under the direction, and chiefly at the expense, of Rowland Burdon, Esq. then M. P. for the county. . It was cast at the foundry of Messrs. Walker, of Rotherham, in Yorkshire, and does honour to the projector and ironmasters. It is nearly double the span of that at Builtwas, and more than double the middle arch of Blackfriar's Bridge. - * Our only doubt of the durability of iron bridges is, that the water, being blown in by storms, rests on the flats of the iron, and tends to corrode it, and waste its parts. The union of cast and wrought iron certainly produces a larger quantity of oxide or rust, than if all is cast, or all wrought iron. Perhaps, if between these thin plates of lead were placed, the two pieces might have their joints closed, by abutting upon the lead, and the same precaution being taken with the wrought iron, where inserted into the grooves of the cast metal, the water would be prevented from entering, or settling in the interstice. Bangor Ferry Iron Hanging Bridge. (See Plate, fig. 1.)— The iron hanging bridge, constructed over the Menai Strait, by Mr. Telford, consists of one opening of 560 feet between the points of suspension, and 100 feet in height between the high- water line and the lower side of the roadway; and the road- way being horizontal, this height is uninterrupted for the whole 560 feet, except where the natural rock, which forms the west- ern abutment, now interposes. But in addition to these 560 feet, there are four arches on the western and three on the eastern side of the main opening, each fifty feet span, making in all 850 feet, as in the plate, fig. 2. In regard to the navigation, it is preferable to any bridge of an arched form, because the latter affords the full height of 100 feet only in the middle ; whereas the former aſſords the same full height for the whole of 500 feet, which is a consider- able advantage to vessels passing the Menai Strait, as it allows. them to stand closer to either shore while passing under the bridge. In regard to economy, this bridge, on the principle of suspension, has equally the advantage, the estimated expense not being more than £70,000: whereas the cheapest of the arched form, made of cost iron, would have cast mearly double that sum. The roadway (Plate, fig. 3,) consists of two carriageways, each 12 feet in breadth, with a footpath of 4 feet between them, so that the platform will be about 30 feet in breadth. The whole is to be suspended from four lines of strong iron cables by perpendicular iron rods, placed 5 feet apart, and these rods will support the roadway framing. The suspending power is cal- culated at 2016 tons, and the weight to be suspended, exclusive of the cables, is 342 tons, leaving a disposable power of 1674 tons. The four sides of the roadways, made of framed iron- work, are firmly bound together for 7 feet in height, and there will be similar work, for 5 feet in depth below the cables. The weight of the whole bridge, between the points of suspension, is 489 tons. - It is calculated that the contraction and expansion of the iron cables may occasion a rise or fall to the extent of four or five inches ; but the variations of the temperature of the atmosphere will not derange the bridge. - The two piers are 60 feet by 42 and a half wide, at high- water mark, having a foundation of rock. These piers, con- nected with the whole of the masonry, form a mass constructed ſae ， -– （ ） t-=] L.- ſºrºrºv，7 %， |- |-|-|- №： № ſ №. ！ ſº ºzºzvy zzozzzzzzz |- |№ſ， -， ſzözz/g/ ../…/，/zz7zzº |- |×ſy ， am||ſm.…|| № | 25， 7， ， ſae， ..………… ſºzzº aerº/ S ±1, ±) (1） | \{{4|| |×- ---- |- | S ： ， | ---- ） |-|- |- |-S §ſºſaeºſº..s. （…） ·， ！， . . . . ： （…： ） （…） ſº： |-：：： -||-|-， . . . . .- |- - -- aer -|-|- . . . . . | … . . .| ----：№ . |- |- B R. I B R I DICTIONARY of MECHANICAL scIENCE. T33 with blocks of hard, limestone, of much greater weight than is necessary for supporting a bridge of this kind. Upon the summit of the two main piers is erected a frame of cast iron, of a pyramidal form, for the purpose of raising the cables from which the bridge is suspended. As the cables are carried from the top of the pyramids, so as to form nearly similar angles on each side, the pressure is almost perpendicular. Along each line there are four cables, making in the whole sixteen; these cables pass over rollers fixed on the summits of the pyramids, and are fastened at their extremities to an iron frame, lying horizontally over the top of the small arches, and under a mass of masonry. From these cables the roadway is suspended by vertical iron rods, connected at their lower extremities with wrought-iron bars, both transversely and longitudinally, thus forming a frame on which timber is laid for the roadway. The distance of five feet is kept between the rods; that the suspending power may be equally distributed throughout the whole length of the bridge. The suspending rods pass between the cables, and depend upon each two of them, so that the general strength of the bridge could not materially be affected by taking one way. The cables and the flooring, as well as the suspending rods, are constructed and united in such a manner, that each of the parts may be taken out and replaced separately; so that there can be no difficulty in repairing any part of the bridge, whenever required. A temporary wire-bridge was made from one abut- ment to the other, to carry over the cables, and arrange the several parts of the bridge, while building. - The weight of each separate cable between the points of suspension is estimated at nine tons and three-quarters, or 117 pounds per yard. The weight of a drove of oxen is calculated at about 300 tons, supposing them to amount to 200 head, all closely huddled together; and the estimated weight necessary to tear the cables asunder is upwards of 2000 tons, which is about four times the weight of the entire bridge. The passing of a mail-coach over the bridge produces no undulation, or sen- sible perpendicular vibration; nor is any lateral vibration apprehended from the most violent gale of wind, by reason of the proportion that the breadth of the bridge bears as a frame to its extreme length. The bars, as well as the segments, are each joined longitudinally to the whole of the required length, and secured by bucklings every five feet, and then enveloped in flannel, well saturated with a composition of rosin and bees- wax, to preserve them from the weather, and the whole are encircled with iron wire.—All these details, will be clearly understood by reference to the engraving that exhibits the passage upon the bridge. The Strand or Waterloo. Bridge. (See Plate, Bridges.)—This bridge, which is now called “Waterloo Bridge,” but which was, still within some few months of its completion, styled “the Strand Bridge,” is a noble ornament of the metropolis. The view of the Surrey hills, and the fine expanse of country that it opens from the Strand, is both delightful and surprising; and the effect is not a little increased by the continuity of houses that every where affects the passenger's eye, in passing along the Strand, till he comes to the grand entrance, leading to Waterloo Bridge. For upwards of a century, a bridge at this particular part of the river had been frequently suggested; but all the merit of the scheme, and the influence of the Bedford family, whose property would be so much improved by the adoption of the plan, did not enable it to resist opposition from the city of London, &c. in former periods. It remained for George Dodd, an enterprising and young civil engineer, after three years' unprecedented turmoil, to get an act of parliament for a bridge at this station; and this was not done till subscrip- tions to the amount of £500,000 had been raised. This was in 1806, Mr. Dodd succeeded in removing the impracticabilities, which had before prevented the scheme of building a bridge across this portion of the river from being carried into effect; and he gave the present plan and dimensions of the bridge. . Some time after the act had been obtained, and the com- mencement of the building, Mr. Dodd disagreed with the com- pany, and separated from them, and the late Mr. Rennie fol. lowed; and he had the honour of finishing this noble bridge, which is different from all the other bridges. All its arches, which are elliptical, are of an equal size; and the road across the bridge is thus made a level road. The style of its archi- tecture is plain; the effect noble, from its simple grandeur; and the materials are of the most durable kind, namely, of granite. It was built with amazing rapidity, and the ceremony of opening it took place June 18, 1817, the anniversary of the battle of Waterloo. The ceremony was of a splendid character, the Prince Regent and the Duke of Wellington being present on the occasion. The following are the dimensions of the bridge:– The length of the stone bridge within the abutments, 1242.ft. Length of the road supported on brick arches on the Surrey side of the river, . . . . . . . . . . . . . . . . . . 1250 Length of the road supported on brick arches on the London side, . . . . . . . & 9 º' º 'º & º º e º a s e s e º e º e º e º e º e 400 Total length from the Strand, where the building begins, to the spot in Lambeth, where it falls to the level of the road, . . . . . . . . . . . . . . . . . . . . . . . . 2890 Width of the bridge within the balustrades,. . . . . . . . 42 Width of the pavement or footway on each side, .. 7 Width of road for horses and carriages,. . . . . . . . . . . . 28 Span of each arch,. . . . . . .*** e º is a s is a º is º 'º e º s s sº e º 'º e s m e 120 Thickness of each pier, . . . . . . . . . . . . . . . . . . . . . . . . . . 20 Clear waterway under the nine arehes, which are equal, . . . . . . . . . . . . . . . . • * * * * * * * . . . . . . . . . . . . . . 1080 Number of brick arches on the Surrey side, ....... 40 The whole of the outside courses of the bridge is Cornish granite, except the balustrades, which are of Aberdeen granite ; and the stones, like those of the Temple of Solomon, were cut to their respective forms at the quarries, before they were brought to London. There are 320 piles driven into the bed of the river under each pier. The length of each pile is from 19 to 22 feet, and the diameter about 13 inches. There is one pile to every yard Square. The scientific manner in which the centres were constructed was admirable ; and as all the arches are of the same size, the centres were removed from those that were finished, and placed on the piers where the arches were not yet thrown : this was an operation that required great skill and care, and was very ably executed. When the centres were removed, so solidly and well was the masonry constructed, that in the middle they only sunk about one inch. Those of the Pont de Neuilly, in France, six miles from Paris, which are nearly similar, sunk about 18 inches in the middle, after the centres were taken away. The scientific principle on which the centres were constructed, which did great credit to Mr. Rennie the engineer, was that of the longi- tudinal incompressibility of timber. The strongest and largest beams of wood bend and yield when pressed upon laterally ; and by that means the form of a centre, constructed in the usual manner, is different when loaded, from what it is when not loaded; but as no weight that men are acquainted with, when acting gradually, will shorten the length of a beam, it was so contrived that the pressure acted always longitudinally or lengthwise, and not laterally or sidewise ; so that those centres remained in form unchangeable, as much as if they had only one solid mass of matter, the two extreme points resting on the *firm and well-constructed piers. In circular arches, such as those of Westminster, or other bridges, the pressure on the centres, before the keystones are put in their place, is not near so good as in elliptical arches, like those of Waterloo. The four toll-lodges are neat appropriate Doric structures. There is a clever contrivance at each lodge, for the purpose of checking. The kind of iron turnstiles, which admit of only one person passing at a time, touch some machinery which com- municates with a clock, locked up in a box in each toll-house, the index of which is thereby moved, so that on looking at it, the number of those who have passed is directly seen. The bridge was only six years in building. It is exactly on a level with the Strand, where it joins, and is 50 feet above the surface of the water of the river Thames. * * The first stone of the bridge was laid on friday, the 11th of October, 1811, by Mr. Henry Swann ; a bottle containing coins of his late Majesty’s reign, was deposited in the first * A . . 2 M 134 B R I B R I DICTIONARY OF MECHANICAL SCIENCE. stone, over which a plate with the following inscription was laid:— - - - - “This foundation of the Strand Bridge was laid on the 11th “ day of October, A.D. 1811, by the Directors for executing the “same, Henry Swann, Esq., M.P. chairman, in the 51st year of “ the reign of King George the Third, and during the regency of “his R. H. George Prince of Wales. The money for building “ which was raised by subscription, under the authority of an “ Act of Parliament. Engineer, Joh N RENNIE, F.R.S.” Wavia hall Bridge. (See Plate, Bridges.)—This bridge was originally projected by Ralph Dodd, the father of the crgineer above alluded to ; and to explain the reason why the name of some branch of this family is so frequently mentioned, it ought to be stated, that scarcely any public work was suggested, about ten or fifteen years ago, that did not proceed from some of them. With the actual building of this bridge, Ralph Dodd had little or nothing to do. See Leigh's Picture of London. Some subscriptions were received, and the building of a bridge on the present site of Vauxhall Bridge was determined on ; but in the co-operation of this, Mr. Dodd was, on account of some. disagreements, dispensed with. Mr. Rennie, the Waterloo Bridge engineer, followed. An immense quantity of good stone was brought; laborious efforts were made to build the piers, &c.; but thousands of pounds were expended to no purpose. . The completion of the bridge was interrupted till Mr. Walker was engaged; and the result was, the building of the present elegant iron bridge. The whole expense of build- ing was within £150,000; and much more is said to have been previously expended in vain. The bridge, however, has a good appearance, together with excellent roads leading to it; and what is more satisfactory, especially to shareholders, the receipts already please the proprietors. The first stone of the bridge was laid in the year 1813, by Prince Charles, the eldest son of the late Duke of Brunswick; and the present beautiful erection was completed in 1816. It consists of nine cast iron arches, with piers formed by a wooden frame as a foundation, faced with Kentish rag stone and Roman cement. It contributes greatly to the beauty of the approaches to the metropolis, and will doubtless eventually occasion considerable improvements in a variety of important respects, by the easy communication which it opens to the inhabitants south of the Thanies—with the houses of parliament and courts of law—and also through Tothill Fields, with Pim- lico, Chelsea, and their populous neighbourhoods. - - Southwark Bridge. (See Plate, Bridges.)—The plan of this bridge was originally proposed and brought forward by Mr. John Wyat, with the view of forming a communication between Bankside, Southwark, and the bottom of Queen-street, Cheap- side. The celebrated Rennie has the merit of the design. It consists of three arches only, of cast iron, from the foundry of Messrs. Joshua Walker and Co. of Rotherham, in York- shire, on massy stone piers and abutments. This is by far the most stupendous iron bridge, and, as respects its centre arch, of greater span than any other in the world. It was opened in April, 1819. Doubts having existed with the unscientific part of the public, as to the practicability of this Herculean structure, whether it could, in its colossal strides, span the frontiers of old father Thames, the following curious and interesting particulars cannot fail to be acceptable. The work, is one of national utility and ornament. France may still boast of the number of her bridges, but since the Strand and Southwark bridges have been built, she no longer can pride herself on the superior magnitude, splendour, or cost- liness of such structures. - This work was begun on the 23d September, 1814, under the direction of Mr. Rennie as engineer, and Mr. Weston, sub- engineer. Messrs. Jolliffe and Banks were the contractors at a lump, or specific sum, and what is rather a novelty in public works of this vast magnitude, it has been completed within the contract price. The expense of the bridge and avenues amounted to £800,000. The distance between the abutments is 708 feet. The extent of each abutment enclosed, including the land arch and invert arch, is 71 feet, formed of solid masonry; all the springing stones of which weigh 13 tons each, and one of granite, similar to the other parts of the bridge stone work. There are two piers, 60 feet high each, from the bed of the river to the top of the parapet, and 24 feet in breadth between high and low water marks, and 75 feet long between acme and acme of the salient angles. The ‘foundations of the piers are each about 12 feet below the bed or bottom of the river, and rest on a platform of 2+ feet thick of solidly compacted timber; and these platforms each further repose on about 420 piles, most of which are driven 24 feet into the earth, making the depth of the earth, from the shoe of the piles to the parapet top of the piers, 98 feet. There are three arches of iron; the two side ones are 210 feet each in span, and the centre arch is 240 feet in span, with 43 feet clear opening above low-water mark, medium tides. Thus it exceeds the admired bridge of Sunderland by 4 feet in the span, and the long-famed Rialto at Venice, by 167 feet. Many of the iron single or solid castings weigh 10 tons each; and the total weight of iron exceeds 5308 tons. The centerings of this bridge on which the arches were formed or turned, were of such a novel and peculiar construction, that the navigation of the Thames was comparatively unimpeded during the building of the bridge. The entire centering of one arch, containing 480 loads of timber, was removed in two tides, having been previously and gradually sunk by loosing of the wedges; unlike the Pont Neuilly, from which the centerings were all struck simultaneously, or rather thrown into the river Seine, and in which the arches settled the surprising depth of 18 inches almost instantly. It was calculated, and allowed, that the centre arch of Southwark bridge would settle at the vertex two inches, yet it has only settled or sunk 1% inch pre- cisely; thus, the wide expanse is within one-eighth of an inch of the figure and form it was originally designed to assume. The following is a specification of the lengths of the º - eet. Waterloo Bridge, within the abutments, .......... 1242 Westminster Bridge, from wharf to wharf, ..... ... 1223 Blackfriar's Bridge, .......... o e º O & © tº * * * * . . . . . . . . 940 London Bridge, .................... tº gº tº ſº e º 'º e º & e . . 900 Vauxhall cast-iron Bridge, ...................... 860 Southwark cast-iron Bridge, between the abutments, 708 London New Bridge, begun 1824.—This bridge, as in the foll- lowing figure, is to consist of five elliptical arches, the central one 150 feet span between the piers; the two next 140 feet each ; and the abutment arches 120 feet each. The height of the middle arch on the under side, above spring tide, 29 feet 6 inches, and at low water 48 feet. The roadway will be 10 feet higher; so that vessels of 200 tons may pass under the bridge by merely lowering their top masts. And the ascent on either side to passengers and carriages will be easier than on the old bridge. This noble structure is to be built of Scottish granite, a marble that is both durable and more beautiful than the Cornish. In our section of this bridge, the piles on which it is rearing are represented, the bed of the river, &c. Tºº-º- Piles . . . . . . . Pºtes 300 feet | T B U R. B U R 135 DICTIONARY OF MECHANICAL SCIENCE. BRIGGS, HENRY, is well known as the improver of Napier's logarithms. This great man was born at Warley Wood, Halifax, Yorkshire, in 1556, and died at Oxford in 1630. He preferred retirement to the splendours of life, and humble probity to the accumulation of vast riches, which his abilities might have procured. .. BROKEN-BACKED, the state of a ship; so loosened in her frame, either by age, weakness, or some great strain, as to droop at each end. This circumstance is more common among the French than the English or Dutch ships, owing partly to their great length, and to the sharpness of their floor, whose breadth is not sufficiently carried from the middle towards each end, and partly from being frequently obliged to have a great weight on both ends, when they are empty in the middle, at the time of discharging one cargo and taking in another. BULK-HEADS, partitions built up in several parts of a ship, to form and separate the various apartments; some of which are particularly strong. Others are light, and removable at pleasure, to clear the ship for action. The bulk-head afore, is the partition between the forecastle and the gratings in the head, and in which are the chase ports. BULL’S EYE, a piece of wood in the form of a ring, which answers the purpose of an iron thin ble : it is seldom used by the English seamen, and then only for the main and fore bow- line bridles. BUMBOAT, a small boat, employed to carry vegetables, &c. for sale, to ships lying at a distance from the shore. BUMIKIN, or Boom KIN, a short boom, or beam of timber, projecting from each bow of a ship, to extend the clue or lower corner of the foresail to windward; for which purpose there is a large block fixed on its outer end, through which the tack is passed, which being drawn tight down, the tack is said to be aboard. - BUNT-LINES, ropes fastened to cringles on the bottoms of the square sails, to draw them up to their yards: they are inserted through certain blocks above, or on the upper part of the yard, whence passing downwards on the forepart of the sail, they are fastened. below to the lower edge, in several places of the bolt rope. . . . . . . . - - - BUNT-LINE Cloth, the lining sewed up the sail in the direc- tion of the bunt-line, to prevent that rope from chaſing the sail. IBUOY, a sort of close cask, or block of wood, fastened by a rope to the anchor, to point out its situation. Buoys are of various kinds, as, Can Buoys, which are in the form of a cone. Of this kind are the buoys which are floated over sands, &c. as marks for ships to avoid then : they are made very large, that they may be seen at a distance; where there are several near each other, they are distinguished by the colour, as black, red, and white. Nun Buoys, are large in the middle, and taper nearly to a point at each end. Wooden Buoys, are solid pieces of light timber, having one or two holes through the ends, in which is fixed a ring of rope called the strop. Cable BUo Ys are common casks, employed to buoy up the cables in rocky anchorage, to prevent their rubbing against the rocks. In the harbour of Alexandria in Egypt, every ship is moored with at least three cables, and has three or four of these buoys on each cable for this purpose. - Life Buoy is generally of the Can kind, though sometimes it is made of cork. It is furnished with a small flag on the top, and is used to throw overboard for a person who has fallen into the sea to lay hold of; while the flag serves to direct a boat to the spot, and thereby frequently saves the life of a fellow creature. w Buoy Rope, the rope which fastens the buoy to the anchor, and should be always of sufficient strength to draw up the anchor; it should also be little more in length than equal to the depth of the water where the anchor lies., BURNING, the action of fire on bodies, whereby the minute parts of them are separated, and thrown into violent motion, some of them assuming the nature of fire themselves, fly off in orbem, while the rest are dissipated in form of vapour, or reduced to ashes. - BURNING Glass, a convex lens which transmits the rays of light, but in their passage refract or incline them towards a common point in the axis called the focus; and by thus com- bining together in a single point the power of all the rays transmitted through the glass, a very great degree of heat is accumulated in that point, which, will fuse bodies that, are infusible in the greatest culinary heat that can be produced. BURNING Mirrors, or Specula, are concave reflecting surfaces, commonly of metal, which reflect the rays of light falling upon them, but at the same time incline them towards a determined point or focus, where their accumulated effect operates in the most powerful manner, burning and dissipating the hardest and most infusible bodies. Those burning glasses which consist of refracting convex lenses, though not entirely unknown, were very imperfectly understood by the ancients; but the latter kind, the burning mirrors, they seem to have had in greater perfection than the moderns, at least if we may credit the relations of several eminent historians, who assert that Archimedes, by means of such mirrors, burned and destroyed the Roman fleet, which, under Marcellus, was employed at the siege of Syracuse ; and that Proclus in the same way destroyed the navy of Vitellius, at the siege of Byzantium. - There are also passages in some of the ancients, which seem to indicate that they also possessed a knowledge of the burn- ing powers of refractors, although their magnifying powers appear to have been wholly unknown to them. Among the moderns, one of the earliest who devised a burning mirror, was the celebrated Lord Napier, the inventor of logarithms. Of the moderns, the most remarkable burning glasses are those of Magine, of 20 inches diameter; of Sepatala, of Milan, near 42 inches diameter, and which burnt at the distance of 15 feet; of Settala, of Vilette, of Tschirnhausen, of Buffon, of Trudaine, and of Parker. That of M. de Vilette was 3 feet 11 inches in diameter, and its focal distance was 3 feet 2 inches. Its substance is a com- position of tin, copper, and tin glass. Some of its effects, as found by Dr. Harris and Dr. Desaguliers, are, that a silver six- pence melted in 73"; a king George’s halfpenny melted in 16", and ran in 34"; tin melted in 3"; and a diamond, weighing 4 grains, lost ºths of its weight. " . That of Buffon is, (see Archimedes' mirror, in the following figure,) a polyhedron, 6 feet broad, and as many high, consist- ing of 168 small mirrors, or flat pieces of looking-glass, each 6 inches square, by means of which, with the faint rays of the sun in the month of March, he set on fire boards of beech wood at 150 feet distance. Besides, his machine has the conveniency of burning downwards or horizontally, as one pleases, each speculum being moveable, so as, by means of three screws, to be set to a proper inclination for directing the rays towards any given point; and it turns either in its greater focus, or in any nearer interval, which our common burning glasses cannot do, their focus being fixed and determined. Buſſon, at another time, burnt wood at the distance of 200 feet; and melted tin and lead at the distance of more than 120, and silver at 50 feet. The following figure represents another contrivance, of Buffon, for diminishing the thickness of very large refracting lenses, in which the burner consists of concentric pieces of glass, each resting upon the other, as represented in the figure, by dividing the convex arch of the lens into three equal parts. | Thus, suppose the diameter to be 26 inches, and the thickness ..ºf 136 * B U R in the middle 3 inches; by -i- the lens into three concentric O's, and laying the one over the other, the thickness of the middle piece need only be one inch; at the same time that the lens will have the same convexity, and almost the same focal distance, as in the other case, while the effects of it must be much greater on account of the greater thickness of the glass. Mr. Parker, of Fleet-street, London, was induced, at an expense of upwards of £700, to contrive, and at length to complete, a large transparent lens, that would serve the pur- pose of fusing and vitrifying such substances as resist the fires of ordinary furnaces, and more espe- cially of applying heat in vacuo, and in other circumstances in which it cannot be applied by any other mean, as in the annexed figure. After directing his atten- tion for several years to this ob- ject, and performing a great va- riety of experiments in the prose- cution of it, he at last succeeded in the construction of a lens of flint glass, 3 feet in diameter, which, when fixed in its frame, exposes a surface of 32 inches in the clear; the distance of the focus is 6 feet 9 inches, and its diameter 1 inch. The rays from this large lens are received and transmitted through a smaller one of 13 inches diameter, its focal length 29 inches, and diame- ter of its focus # inch; so that this second lens increases the power of the former, as 82 to 3°, or rather more than 7 to 1. In the elevation, (as in the following figure,) A is the lens of DICTIONARY OF MECHANICAL SCIENCE. B U. S. the diameter mentioned; B is a second lens, 16 inches diame. ter; C a truncated cone, composed of 21 ribs of wood, in which both lenses are fixed; D is a rack passing through the pillar L; E its handle; F a bar of wood, fixed between the two lower ribs of the come at G, in which the apparatus H, with the iron plate I, turning on the ball and socket K, to hold thereon the matter under experiment; L L a frame moving on the castors M M. Below the table N are three friction wheels, that move the machine horizontally. O a strong iron bar, in which the lens and the cone hang. - The following figure represents the section. a is the great lens marked A in the elevation ; b the frame containing the great lens; t the small lens marked B; d the frame that con- tains the small lens; e the truncated come C ; f the bar on which the apparatus F turns; g the iron plate marked I; h the cone of rays formed by the great lens a falling on the lens t ; i the cone of rays formed by the refraction of the lens t. In the front view in Mr. Parker's lens, A is the great lens in its cir- cular frame; m the iron bow in which it hangs ; l the support. From a variety of experiments made with this lens, the fol- lowing are selected to serve as a specimen of its powers:— Substances fused, with their Weight and Weight in Time in Time of Fusion. Grains. Seconds. Gold,. . . . pure, . . . . . . . . . . . . . . . . . . . . . . 20 . . . . . . 4 Silver, ... ditto, . . . . . . . . . . . . . . . . . . . . . . 20 . . . . . . 3 Copper, ditto, . . . . . . . . . e e º e º ºs e º 'º a e e s 33 . . . . . . 20 Platina, ditto, . . . . . . . tº tº e o 'º a c e e º e º e º e 10 . . . . . . 3 Nickel, . . . . . . . ... . . . . . . . . © e < e s e º 'º e º º 16 . . . . . . 3 Bar iron, a cube, . . . . . . . . . . . . . . . . . . . . 10 . . . . . . 12 Cast iron, ditto, .... . . . . . . . . . . . . . . . . . 10 . . . . . . 3 Steel, . . . . ditto, . . . . . . . . . . . . . . . . . . . . . 10 . . . . . . T2 Scoria of wrought iron,... . . . . . . . . . . . . . 12 . . . . . . 2 A topaz, or chrysolite, . . . . . . . . . . . . . . . . 8 . . . . . . 45 An oriental emerald, . . . . . . . . . . . . . . . . . 2 . . . . . . 42 Crystal pebble,. . . . . . . . . . . . . . . . . . . . . . 7 . . . . . . 6 Topaz, . . . . . . . . . . . . . . . • * * * * * * * * * * * * * * 10 . . . . . . 30 Flint oriental............ . . . . . . . . . . . . . . . 10 . . . . . . 30 Rough cornelian . . . . . . . . . . . . . . . . . . . . 10 . . . . . . 75 Jasper, . . . . . . . . . . . . . . . . . . tº e a e º & e º s tº º 10 . . . . . . 25 Onyx, . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 . . . . . . 20 Garnet, . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 . . . . . . 17 White rhomboidal spar, . . . . . . . . . . . . . . 10 . . . . . . 60 Mr. Parker farther informs us, that a diamond weighing 10 grains, exposed to this lens for 30 minutes, was reduced to 6 grains ; but gold remained in its metallic state, without appa- rent diminution, notwithstanding an exposure at intervals of many hours. With regard to experiments on iron, it is remark- able that the lower part, viz. the part in contact with the char- coal, was first melted, when that part which was exposed to the focus remained unfused. For farther particulars on this subject see Rees's Cyclopedia, article Burning Glass; see also an essay on “Mirrors Ardens,” by M. Peyrard, subjoined to the French translation of the works of Archimedes. BURTHEN, or BURDEN, the weight or measure of any spe- cies of merchandise that a ship will carry when fit for sea; the general rule for finding which is, to multiply the length of the keel, the inner midship breadth, and the depth from the main deck to the plank joining the keelson, together; which product | divided by 94 gives the tonnage, or burden, required in tons. BUSHEL, a measure for dry goods, which by an act of parliament, passed in 1697, is to contain 2150-42 cubic inches, viz. “Every round bushel, with a plain and even bottom, is to B, U T. B U T 137 DICTIONARY OF MECHANICAL | SCIENCE. be made 18% inches wide throughout, and 8 inches deep, which is accounted a legal Winchester bushei, according to the stand- ard in his majesty's exchequer.” See WEIGHTs and MEASUREs. BUTTER, Cheese, &c.—Butter is an artificial preparation of cow’s milk. The milk, either in its natural state or in that of cream, is whirled round or agitated in a churn, till all its unc- tuous particles are separated from the whey, and a soft con- sistent mass is formed.* Greek authors frequently speak of milk and cheese, but do not mention butter; and the Romans, for six centuries, used it as a medicine. In modern times, the art of making, improving, and preserving butter, has kept pace with the unwholesome custom of eating this animal oil from an early period of infancy. Butter forms a considerable article of trade. 50,000 tons of butter are annually consumed in Lon- don; of which the counties of Cambridge and Suffolk are said to furnish 50,000 firkins, each containing 56 lbs. None, how- ever, is equal to that produced in Essex, and known by the name of Epping butter. - Butter, like all inflammable substances, is constantly under- going oxygenation, as the chemists call it, and by this process becomes rancid, or is changed into a new substance no longer suitable for the purposes of nourishment. The tendency to rancidity, or oxygenation, is much hastened by its greater or less admixture with the other parts of the milk, from which it is not totally freed; for if the parts are very completely sepa- rated, the progress of oxygenation is much retarded. The only means of preserving butter is by means of sea-salt; and with this addition it can be kept long in a fit condition for aliment. The cream, or oily part of the milk, from which but- ter is made, acquires, by being kept for some time, new pro- perties, and these new properties facilitate its conversion into butter. Thus sour cream does not take one-fourth part of the labour necessary in churning, as fresh cream, in order to give out its product; but this acid which prevails in the cream before churning, disappears also after the process is finished ; and this circumstance is no way influenced either by the access or exclusion of the atmospheric air. Fresh butter, as first made, is almost without any smell, of a mild and agreeable taste, easily soluble in water, and remaining uniform even in a boiling heat. As its acid becomes extricated, it acquires an acrimony or rancidity, and is then rendered unwholesome.— This acid is peculiar, and has not yet been properly examined. The proper quality of butter is marked by its oily or fat shining surface, and its yellow colour, with an agreeable flavour and sweetish taste. The colour varies according to the feeding of the animal, and to supply its defect, adventitious means are often resorted to by colouring it with vegetables. The highest degree of natural colour is generally found in that from the milk of Guernsey cows. From the strong tendency of butter to oxygenation, great quantities of this article come to be sold in a rancid state ; and this cannot fail to be attended with the most deleterious consequences, and to lay the foundation of * There are also vegetable butters made from palm oil, and the oil of the cocoa nut. The celebrated Park ſound, in Africa, a tree called by the natives shea, from the fruit of which a tolerably pure butter was procured. shire, and that of the adjoining counties. disease. As the wholesomeness of this article depends on its freedom from rancidity, whatever operation it is subjected to, that produces this state of it, introduces the foundation of disease, whether it arise from keeping, or the processes of cookery in frying and burning. It becomes in this state heavy and indigestible on the stomach, occasioning acrid and acid belchings. - But besides selling it in a rancid state, other deceptions may be adduced in respect to butter, by those who deal in it. By beating, it possesses the quality of absorbing an immense quantity of water. Such advantage is taken of this circum- stance, that what with the additional weight of salt also intro- duced into it, the public do not receive more than two-thirds of the actual product when they buy it. The fraud begins from the very dairy, and is increased when it gets into the hands of the cheesemonger. The poor man is deprived of so much of the nourishment which he ought to have, and, by an excess of extraneous matter introduced into his body, through the use of this sophisticated article, sees himself and his progenitors often suffering under scrofula and other maladies, drawing their origin from, or aggravated by, this impure source. . . Cheese, made from curdled milk, freed from the serum or whey, and afterwards dried for use, differs in quality, as it is made from new milk, or from skimmed milk,-from the curd which separates.spontaneously upon standing, or that which is more speedily produced with runnet. There is also cheese from cream, which is fat and butyraceous, and does not keep long. Of all the cheese made in England, none is so esteemed as the Stilton. These cheeses must be kept two years before they are properly mellowed for use in families. The making of what is called Stilton cheese is not confined to the Stilton farmers. Others in Huntingdonshire, and even in Rutland and Northamptonshire, make a similar sort, which is sold under the name of Stilton. The double Gloucester is much esteemed. The goodness of Chedder cheese is said to be owing to the richness of the land: the same is the case with the Somerset- Cheshire cheese is generally admired. A cheese is sometimes above a hundred pounds weight. To give a high colour to cheese, it is usual to put with the milk, before it is turned, a little annotto. No cheese will look yellow without it, and though it is perfectly innocent, it does not add to the goodness of the cheese. BUTTERFLY, To take the Impression of a. Having caught a butterfly, kill it without spoiling its wings, contrive to spread these out as regularly as possible in a flying position; then, with a small brush or pencil, take a piece of white paper; wash part of it with gum water, afterwards lay your butterfly on the paper, cut off the body close to the wings, throw it away, lay the paper on a smooth board, with the fly upwards; lay another paper over that, put the whole preparation into a Screw press, and screw it hard down, or otherwise press it, for half an hour. Afterwards, take off the wings of the butterfly, and you will find their perfect impression, with all their various colours marked distinctly, on the paper. When this is done, draw between the wings of your impression the body of the butterfly, and colour it after the insect itself. == C. C A B CABIN, a room or apartment in a ship, where any of the officers usually reside. In a large ship there are several cabins, the principal of which, distinguished by the name of the great cabin, is designed for the captain or commander. In ships of the line, this chamber is furnished with an open gal- lery in the ship's stern, as also a little gallery on each quarter. CABINET, a secret or inner apartment; also a piece of joiner's work resembling a press or chest; likewise a council, pr select meeting, is called a cabinet. C A B CABLE, a thick, stout rope, made of hemp, &c. to keep a ship at anchor. Every cable is of three strands, every strand of three ropes, every rope of three twists; and the twists are spun of more or less threads, as the cable is to be thick or small. Thus, a cable of one inch diameter, or three inches circumference, consists of forty-eight ordinary threads, and weighs 192 pounds. To estimate the strength of a hempen cable, divide by 5, the square of its girth in inches, and the quotient will express in tons the utmost strain it can bear. 2 N - I38 C A L C. A L DICTIONARY OF MECHANICAL SCIENCE. Hence, a rope of 1 inch diameter is capable of bearing a strain of 1-8 ton. Circum. Thread. Weight.—lbs. Strain.--Tons. 4. . . . . . . . . . . . . . . 77 . . . . . . . . . . .308 ... 3-2 6 . . . . . . . . . . 174 . . . . . . . . . . 696 . . . . . . 72 8 . . . . . . . . . . . . . . 31 l . . . . . . . . . . 1244 . . . . . . 12'8 10 . . . . . . . * * * * * * * 485 . . . . . . . . . . 1940 . . . . . . 20:0 14 . . . . . . . . . . . . . . 952 . . . . . . . . . . 3808 . . . . . . 39-2 18 . . . . . . . . . . . . . . 1574. . . . . . . . . . . 6296 . . . . . . 64'8 20 . . . . . . . . . . . . . . 1943 . . . . . . . . ... 7772 . . . . . . 80-0 This estimate applies to new ropes, formed of the best mate- rials, not much twisted, and having the strands laid even. If yarns, of 180 yards long, be worked up into ropes 120 yards only, it will lose one-fourth of the strength, the exterior fibres alone resisting the greatest strain. The long cable is not so apt to break as the short one, because it will bear a great deal more stretching before it comes to the greatest strain; it therefore resembles a sort of spring, which may be very easily extended, and afterwards recovers its first state, as soon as the force which extended it is removed. Besides all this, a ship will ride much smoother with a long cable, and be less apt to pitch or plunge deep in the water with the fore part. On the contrary, the short cable, being too nearly vertical to the anchor, cannot bear such a strain, because it is charged with a greater effort; and, as it will not bear stretching, may break the first violent tug. The ship also rides with much greater difficulty, labours extremely, and often plunges all her fore part under water. Every ship should be furnished with sufficiency of cables, or what is called ground tackle ; for owing to a deficiency of this necessary article, many excellent vessels have been lost, and it is an in- considerate policy indeed, in merchants, to expose their ships to such evident dangers for the want of them. CAGE, an enclosure of wire, or wicker, for the confinement of birds or wild beasts. CAG e means also, in carpentry, some outer work, or timber enclosing other timber, as, the cage of a windmill; the cage of a staircase, the wooden walls or sides that enclose it. CALAMINE, a mineral composed of zinc, iron, and some- times other substances ; its colour is sometimes whitish or gray; at other times brown or blackish, red or deep yellow. CALAMUS, the rotang, or true Indian cane, abundant in Sumatra, is one of those plants from which the drug, called dragon’s blood, is obtained. CALASH, a small light chariot, or garden chair, of which a new sort going on two wheels has been invented; not hung on traces and springs, yet easier than the common coaches, and possessing the singular advantage of recovering its proper position, should it, by any irregularity of the road, or other accident, be overturned. CALCAR, a small oven, or reverberatory furnace, in which the first calcination of sand and potashes is made, for turning them into frit, from which glass is ultimately made. This fur- nace, 10 feet long, 7 wide, 2 deep, is heated by flame reverbe- rating from the roof upon the frit, over the surface of which the smoke rolls quite black, escaping by the mouth of the cal- car. The coals burn on grates of iron, to allow the ashes to precipitate. CALCAREOUS EARTH, the same as lime, and of which there are various combinations, as marble, limestone, marle, gypsum. Vast quantities of marine shells, and the bones of animals, are found imbedded in it. ' CALCINATION. See CHEMISTRY. CALCULATION, the act of computing, as in Arithmetic, Astronomy, Geometry, &c. CALCULUS, among Mathematicians, denotes a certain way of performing mathematical operations. CALculus, in Medicine, the disease of the stone in the blad- * der or kidneys; the term is Latin, and signifies a little pebble. Hard waters, that contain limy earth, contribute to the forma- tion of human calculi. CALEN DAR, in Chronology, a distribution of time, accommodated to the purposes of civil life, exhibiting the order of days, weeks, months, festivals, &c. that happen and succeed in the course of one year. The calendar of Romulus, or the ancient Romish year, consisted of ten months, namely, Martius of thirty-one days, Aprilis of thirty, Maius of thirty- one, Junius thirty, Quintilis, of thirty-one, Seactilis of thirty, September of thirty, October of thirty-one, November of thirty, December of thirty ; in all, three hundred and four days. The Roman year of Numa consisted of twelve months. Januarius had twenty-nine days, Februarius twenty-eight, Mar- tius thirty-one, Aprilis twenty-nine, Maius thirty-one, Junius twenty-nine, Quintilis thirty-one, Seactilis twenty-nine, Septem- ber thirty-one, October twenty-nine, November twenty-nine ; December twenty-nine; in all, three hundred and fifty-five. The months called Quintilis and Sextilis, from their order in Romulus's year, were changed into Julius and Augustus, in honour of Julius Caesar and his successor Augustus. - The Julian year consists of twelve months, viz. January o thirty-one days, February of twenty-eight, March of thirty-one, April of thirty, May of thirty-one, June of thirty, July of thirty- one, August of thirty-one, September of thirty, October of thirty- one, November of thirty, December of thirty-one ; in all three hundred and sixty-five. Every fourth year, in the Julian account, has three hundred and sixty-six days, February then having twenty-nine, as we have before observed. The Gregorian year has the same number of months and days as the Julian, the only difference being that each month in the former begins eleven days sooner than the latter. • The Jewish year consists of twelve months. Nisan or Abib has thirty days, Jiar or Zius twenty-nine; Siban or Sivan thirty, Thamus or Tamus twenty-nine, Ab thirty, Elul twenty-nine, Tisri or Ethanim thirty, Marchescan or Bul twenty-nine, Cislew thirty, Tebeth twenty-nine, Shebat or Schebeth twenty-nine, Adar twenty-nine; in all three hundred and fifty-four. This is made to agree with the solar year, by adding eleven, and sometimes twelve days. As the form of the year is various among different nations, so likewise is its beginning. The Jews, like other nations of the East, had a civil year, which commenced with the moon in September; and an ecclesiastical year, which began from the new moon in March. The Persians begin their year in the month answering to June. The Chinese and most of the Indian nations begin it with the first moon in March; and the Greeks with the new moon that happens next after the summer solstice. '. In England, the civil or legal year formerly commenced on the 25th of March, and the historical year on the first day of January. But since the alteration of the style, in 1752, the civil year, in this country, as we observed before, has likewise begun on the first of January. CALENDS, or KALENDs, in the Roman Chronology, the first day of every month. It was one of the offices of the pontifices to watch the appearance of the new moon, and give notice thereof to the high priests; upon which a sacrifice being offered, the pontiff summoned the people together in the Capi- tol, and there with a loud voice proclaimed the number of calends, or the day whereon the nones would be ; which he did by repeating a formula as often as there were days or calends. And hence also our term calendar. The Nones were the 5th day of January, February, April, June, August, September, November, and December, and the 7th of March, May, July, and October. And the Ides hap- pened 9 days after the nones; that is, on the 13th day of February, April, June, August, September, November, and December; and on the 15th of March, May, July, and October. CALIBER, or CALIPER, properly denotes the diameter of any round body: thus we say the caliber of the bore of a gun, the caliber of a shot, &c. CALIBER or CALIPER Compasses, or simply Calipers, a sort of compass made with bowed or arched legs, for the purpose of taking the diameter of any round body. CALICO, a cloth made from cotton wool, resembling linens; the name is from Calicut, a city in India, from whence the Spaniards or Portuguese first brought calicoes. CALIco-PRINTING, or the art of applying coloured patterns on a white or coloured ground of linen or cotton, has been practised in India for more than two thousand years, but has not been cultivated in Europe more than a century. This art depends on the action of certain bodies, which, by chemical agency, permanently unite the colouring matter of dyeing C A L C A L DICTIONARY OF MECHANICAL SCIENCE. 139 materials to particular parts of the cloth. The substances which bind the colouring matters to the faces of the cloth, are denominated mordants. The mordant is applied to the cloth by wooden blocks, in which the patterns are carved in relief. This effect is also produced by means of a small brush, by sheet copper fixed in a block, like filligree work, or by the copper- plate. When the mordant has been applied, the cloth is made completely dry; and washed in water, till the thickening mat- ter, and those parts of the mordants uncombined with the cloth, are removed. After this, the cloth is rinsed in clean water. It is then dipped in the dye liquor, by which the whole is dyed. The parts which have been impregnated in the mor- dant receive a brighter colour than those which have not. The colour of the former is permanent, but that of the latter is discharged by repeated washing. * . Calico-printing, we have said, consists in impregnating those parts of the cloth which are to receive a colour, with a mor- dant, and then dyeing it as usual with some dye stuff or other. The dye stuff attaches itself firmly to that part of the cloth only which has received the mordant. The whole surface of the cotton is indeed more or less tinged, but by washing and bleaching, all the unmordanted parts resume their original colour, while those which have received the mordant retain it. Let us suppose, that a piece of white cotton cloth is to receive red stripes; all the parts where the stripes are to appear are pencilled over with a solution of acetite of alumine ; after this, the cloth is dyed in the usual manner with madder. When taken out of the dyeing vessel it is all of a red colour, but by washing and bleaching, the madder leaves every part of the cloth white, except the stripes impregnated with the acetite of alumine, which remain red. Thus it is obvious, that it is not the cloth but the mordant which has retained the dye. In the same manner may yellow stripes, or any other wished-for figure, be given to cloth, by substituting quercitron bark, weld, &c. for madder. When different colours are to be given to different parts of the cloth at the same time, it is done by impregnating it with various mordants. Thus, if stripes be drawn upon a cotton cloth with acetite of alumine, and other stripes with acetite of iron, and the cloth be afterwards dyed in the usual way with madder, and then washed and bleached, it will be striped red and brown. The same mordants with quercitron bark, give yellow and olive, or drab. The mordants employed in calico-printing are, acetite of alumine, and acetite of iron. These mordants are applied to the cloth, either with a pencil, or by means of blocks. As the mordants are applied on to particular parts of the cloth, care must be taken that none of them spread to the part of the cloth which is to be left white, and that they do not interfere with one another, when more than one are applied. If these precau- tions be not attended to, all the elegance and beauty of the print will be destroyed. It is necessary, therefore, that the mordants should be of such a consistence, as not to spread beyond those parts of the cloth on which they are applied. This is done by thickening them with flour or starch, when they are to be applied by the block; and with gum arabic, when they are to be put on by a pencil. The thickening should never be greater than is suffi- cient to prevent the spreading of the mordants; when carried too far, the cotton is apt not to be sufficiently saturated with the mordants; and of course, the dye takes but imperfectly. In order that the parts of the cloth impregnated with mordants may be distinguished by their colour, it is usual to tinge the mordants with some colouring matter or other. The printers commonly use the decoction of Brazil wood for this purpose; but the Brazil wood colouring matter impedes the subsequent process of dyeing. The mordant should therefore be coloured with some of the dye stuff afterwards to be applied, but not more than is sufficient to make the mordant distinguishable when applied to the cloth. The reason is obvious. If too much dye be mixed with the mordant, a great proportion of the mordant will be combined with colouring matter, which must weaken its affinity for the cloth, and of course prevent it from combining with it in sufficient quantity to ensure a permanent dye. Sometimes these two mordants are mixed together in different proportions; and sometimes one or both is mixed with | parts of the cloth which are to remain white. an infusion of sumach, or of nut galls. By these contrivances. a great variety of colours are produced by the same dye stuff. After the mordants have been applied, the cloth is dried by artificial heat, which contributes towards the separation of the acetous acid from its base, and towards its evaporation, by which the mordant combines in a greater proportion, and more intimately with the cloth. § When the cloth is sufficiently dried, it is to be washed with warm water and cow-dung, till all the flour, or gum, employed to thicken the mordants, and all those parts of the mordants which are uncombined with the cloth, be removed. After this, the cloth is thoroughly rinsed in clean water. Almost the only dye stuffs employed by calico-printers, are indigo, madder, and quercitron bark, or weld. This last substance, however, is but little used by the printers of this country, except for delicate greenish yellows. The quercitron bark has almost superseded it, because it gives colours usually good, and is much cheaper and more convenient, not requiring so great a heat to fix it. Indigo not requiring any mordant, is commonly applied at once, either with a block or a pencil. It is prepared by boiling together indigo, potash made caustic by quicklime, and orpi- ment; the solution is afterwards thickened with gum. It must be carefully secluded from the air, otherwise the indigo would soon be regenerated, which would render the solution useless. Coarse brown sugar, as a substitute for orpiments, is equally efficacious in decomposing the indigo, and rendering it soluble; while it likewise serves all the purposes of gum. When the cloth, after being impregnated with the mordant, is sufficiently cleansed, it is dyed in the usual manner, and the whole is more or less tinged with the dye stuff. It is well washed, and then spread out for some days on the grass, and bleached with the wrong side uppermost. This carries the colour off completely from all parts of the cotton which have not imbibed the mordant, and leaves them of their original whiteness, while the mordanted spots retain the dye as strongly aS 6V6T. - We will now give some examples of the manner in which printers give particular colours to calicoes. Some calicoes are only printed of one colour, others have two, others three or more, even to the number of eight, ten, or twelve. The smaller the number of colours, the fewer in general are the processes. One of the most common colours on cotton prints is a kind of nankeen yellow, of various shades, down to a deep yellowish brown, or drab. It is usually in stripes or spots. To produce it, the printers besmear a block, cut out into the figure of the print, with acetite of iron, thickened with gum or flour; and then apply it to the cotton, which, after being dried and cleaned in the usual manner, is plunged into a potash ley. The quantity of acetite of iron is always proportioned to the depth of the shade. For yellow, the block is besmeared with acetite of alumine. The cloth, after receiving the mordant, is dyed with quercitron bark, and then bleached. Red is communicated by the same process, only madder is substituted for the bark. The fine light blues which appear so often on printed cottons, are produced by applying to the cloth a block besmeared with a composition, consisting partly of wax, which covers all those The cloth is then dyed in a cold indigo wat; and after it is dry, the wax compo- sition is removed by hot water. Lilac brown, and blackish brown, are given by means of acetite of iron; the quantity of which is always proportioned to the depth of the shade. For very deep colours, a little sumach is added. The cotton is afterwards dyed in the usual manner with madder, and then bleached. Dove colour and drab, by acetite of iron and quercitron bark. When different colours are to appear in the same print, a greater number of operations are necessary. Two or more blocks are employed, upon each of which, that part of the print only is cut, which is to be of some particular colour. These are besmeared with different mordants, and applied to the cloth, which is afterwards dyed as usual. Let us suppose, for instance, that these blocks are applied to cotton, one with acetite of alumine, another with acetite of iron, a third with a mixture of those two mordants, and that the cotton is then dyed with quercitron bark, and bleached. The parts impreg- nated with mordants would have the following colours:—Ace- 140 C A M O A. L. DICTIONARY of MECHANICAL scIENCE. tite of alumine, yellow ; acetite of iron, olive, drab, dove; the mixture, olive green, olive. tº tº ºn tº If the part of the yellow be covered over with the indigo liquor, applied with a pencil, it will be converted into green, If the same liquid, blue may be given to such parts of the print as require it. If the cotton be dyed with madder, instead of quercitron bark, the print will exhibit the following colours :— Acetite of alumine, red; acetite of iron, brown, black; the mix- ture, purple. * g When a greater number of colours are to appear; for in- stance, when those communicated by bark, and those by mad- der, are wanted at the same time, mordants for part of the pattern are to be applied; the cotton is then to be dyed in the madder bath, and bleached; then the rest of the mordants, to fill up the pattern, are added, and the cloth is again dyed with quercitron bark, and bleached. The second dyeing does not much affect the madder colours; because the mordants, which render them permanent, are already saturated. The yellow tinge is easily removed by the subsequent bleaching. Some- times a new mordant is also applied to some of the madder colours, in consequence of which, they receive a new perma- nent colour from the bark. After the last bleaching, new colours may be added by means of the indigo liquor. The following table will give an idea of the colours which may be given to cotton by these complicated processes.—1. Madder Dye. Acetite of alumine, red; acetite of iron, brown, black; acetite diluted, lilac ; both mixed, purple.—2. Bark Dye. Ace- tite of alumine, yellow ; acetite of iron, dove, drab ; lilac and acetite of alumine, olive; red and acetite of alumine, orange. –3. Indigo Dye. Indigo, blue; indigo and yellow, green. Thus no less than twelve colours may be made to appear together in the same print, by these different processes. These instances will serve to give the reader an idea of the nature of calico-printing, and at the same time afford an excellent illustration of the importance of mordants in dyeing. Were it possible to procure colours sufficiently permanent, by applying them at once to the cloth by the block or the pen- cil, as is the case with the mordants, the art of calico-printing would be brought to the greatest simplicity; but at present this can only be done in one case, that of indigo ; every other colour requires dyeing. Compositions, indeed, may be made, by previously combining the dye stuff and the mordants. Thus yellow may be applied at once, by employing a mixture of the infusion of quercitron bark, and acetite of alumine, red, by mixing the same mordant with the decoction of alumine, and so on. The colours applied in this way, are, unfortunately, far inferior in permanency to those produced when the mordant is previously combined with the cloth, and the dye stuff after- wards applied separately. In this way are applied almost all the fugitive colours of calicoes, which washing, or even expo- sure to the air, destroys. CALIPPIC Period, in Chronology, a period of 76 years, continually recurring, after which it was supposed by Calippus, that the lunations, &c. of the moon would return again in the same order; which, however, is not exact, as it brings them too late by a day in 225 years. CALOMEL, dulcified sublimate of mercury, is a combina- tion of mercury with muriatic acid; called also sub-muriate of mercury. CALORIC, in Chemistry, a modern term introduced into philosophy, to denote that substance, by the influence of which are produced all the phenomena of heat, , and which was formerly distinguished by the term igneous fluid, matter of heat, and other analogous demonstrations. Heat, considered as a sensation, or, in other words, sensible heat, is only the effect produced upon our organs by the motion of caloric, disengaged from surrounding bodies. To illustrate this, let us observe, that in general we receive the impression only in consequence of motion, and it might be established as an axiom, that without motion there is no sensation. This general principle applies very accurately to the sensations of heat and cold. When we touch a cold body, the caloric, which always exerts itself to attain an equilibrium in all bodies, passes from our hand into the body we touch, and give us the feeling or sensation of cold. The contrary happens when we touch a warm body; the caloric them, in passing from the body into our hand, produces the sensation of heat. If the hand and the body it touches be of the same temperature, or very nearly so, we receive no impression of either heat or cold, because there is no motion or passage of caloric. When the thermometer rises, it shews that the free caloric is entering into the surrounding bodies. The thermometer, which is one of these, receives it in proportion to its mass, and to the capacity which it possesses for containing caloric. Free caloric is that which is not combined in any manner with any body. But as we live in a system, to the matter of which caloric has a very strong affinity, we are never able to obtain it in a state of absolute freedom. * - Combined CALoric is that which is fixed in bodies by affinity, or elective attraction, so as to form part of the substance of the body. Specific CALoric. By the expression of specific caloric of bodies, we understand the respective quantities of caloric requisite for raising a number of bodies, of the same weight, to an equal degree of temperature. This proportional quantity of caloric depends upon the distance between the constituent particles of bodies and their greater or less degree of cohesion; and this distance, or rather the space or void resulting from it, is called the capacity of bodies for containing caloric. Caloric is the cause of fluidity and of vapour. f - * Bodies which transmit caloric easily, are called conductors of caloric; and according to the power of doing this, they are termed good or bad conductors. Those which do not transmit heat at all, or with great difficulty, are called non-conductors. The best conductors of heat are metals, and the best non-con- ductors of fluids are water and air. Charcoal is also con- sidered as a non-conductor. Heat is produced by collision, friction, chemical action, the solar rays, electricity, galvanism, &c. The instruments for measuring its intensity are called Pyrometers. See FIRE. - CALX, lime, but a dignified title for any powder remaining after burning a metal ; and because in burning the metal imbibes oxygen, and the powder from it becomes heavier than the metal was before, all metallic calces are now-a-days called orides, and rust is also an oxide. CAMBLET, a stuff made of wool, hair, or silk, and some- times of all these mixed. CAMBRIC, a species of linen made of flax, very fine and white, deriving its name from Cambray, in France, where this cloth was first made. - CAMEL is the name given to a machine, employed by the Dutch for carrying vessels heavily laden over the sandbanks in the Zuyder-Zee. In that sea, opposite to the mouth of the river Y, about six miles from the city of Amsterdam, there are two sandbanks, between which is a passage called the Pam- pus, sufficiently deep for small vessels, but not for those which are large and heavily laden. On this account, ships which are outward bound take in before the city only a small part of their cargo, receiving the rest when they have got through the Pampus. And those that are homeward bound must, in a great measure, unload before they enter it. For this reason, the goods are put into lighters, and in these transported to the warehouses of the merchants in the city; and the large vessels are then made fast to boats by means of ropes, and in that manner towed through the passage to their stations. Though measures were adopted so early as the middle of the sixteenth century, by forbidding ballast to be thrown into the Pampus, to prevent the further accumulation of sand in this passage, that inconvenience increased so much from other causes as to occasion still greater obstruction to trade ; and it at length became impossible for ships of war, and others heavily . laden, to get through it. About the year 1672 no other remedy was known than that of making fast to the bottoms of ships large chests filled with water, which was afterwards pumped out; so that the ships were buoyed up, and rendered sufficiently light to pass the shallow. By this method, which was attended with the utmost difficulty, the Dutch carried out their numerous fleet to sea in the above-mentioned year. This plan, however, gave rise soon after to the invention of the camel, by which the labour was rendered easier. \ . The camel consists of two half ships, constructed in such a manner that they can be applied below water, on each side of C. A M C. A. N. 141 U ICTIONARY OF MECHANICAL SCIENCE. the hull of a large vessel. On the deck of each part of the camel are a great many horizontal windlasses, from which ropes proceed through apertures in the one half, and, being carried under the keel of the vessel, enter similar apertures in fhe other, from which they are conveyed to the windlasses on its deck. When they are to be used, as much water as may be necessary is suffered to run into them ; all the ropes are cast loose, the vessel is conducted between them, and large beams are placed horizontally through the port holes of the vessel, with their ends resting on the camel on each side. When the ropes are made fast, so that the ship is secured between the two parts of the camel, the water is pumped from them, by which means they rise, and float the ship with them. Each half of the camel is about 130 feet long, and 22 to 13 feet broad. The hold is divided into several compartments, that the machine may be kept in equilibrio while the water is flowing into it. A vessel drawing 15 feet water, can be made to draw only 11 by the camel ; and ships of war of 100 guns, can be raised to pass without grounding the shallow banks of the Zuyder-Zee. The Russians” employ similar machines to float vessels built in the Neva, over the intermediate sand- banks. Camels are also used at Venice. CAMELOPARDALIS. The Camelopard is a modern con- stellation, that has been formed by Hevelius. Its boundaries and contents are: north by the pole of the world, east by Ursa Major and Lynx, south by Perseus and Auriga, and west by Perseus, Cassiopeia, and Tarandus; right ascension 68°, declination 70° north. It consists of 58 small stars, five of the fourth magnitude, and the rest smaller. The most conspicuous star is nearly on the Arctic Circle, on the near hind thigh. This constellation extends from Auriga to the North Pole, by which position it can be the better traced in the heavens. CAMERA LUCIDA, or Light Chamber, a contrivance of Dr. Hook, to make the image of any object appear on a wall, in a light room, either by day or night. Dr. Wollaston has recently invented a portable instrument for drawing in perspective, to which he has given the name of camera lucida. CAMERA Obscura, or Dark Chamber, in Optics, a machine or apparatus, so constructed, that principally by means of a con- vex glass, or a convex glass and plane mirror, the images of external objects are represented on a rough ground plane glass, white paper, or other surface, in the most vivid and distinct manner, with all their natural colours, motions, &c. The use of the Camera Obscura is various: it assists very much in explaining the nature and rationale of vision; and hence by some it has been compared to an artificial eye. It exhibits the most striking and entertaining representations of objects of all descriptions, whether near or distant, in their true perspective; the colouring just and natural, their light and shadows correct, and all their motions and relative positions according to the original. By means of this instrument, a per- son, however unacquainted with drawing, may delineate objects with great facility and correctness; and to the skilful artist it will be found indispensably useful in comparing his sketches with the perfect representations given in the camera; and by observing his defective imitations, he may correct as much as possible his designs. The theory of the Camera Obscura will be readily compre- hended from the annexed figure, in which the object AB radiates through a small aperture, C, upon a white wall opposite to it, and if the place , of radiation behind the aperture b C a be dark, the image of the object will be painted on the wall, in an inverted position; for the aperture ... : * * C being very small, the rays issuing from the point B will fall on b ; those from points A and D will fall on a and d ; where- fore, since the rays issuing from the several points are not con- founded, they will by reflection exhibit its appearance on the wall. But since the rays A C and B C intersect each other in the aperture, and the rays from the lowest points fall on the highest, the situation of the object will of necessity be inverted. A. B i ; * It was introduced into Russia by Peter the Great, who obtained the model of one, when he worked in Holland as a common ship-carpenter. If the wall where the object is delineated be parallel to it, a b : A B :: d C : D C, that is, the height of the image will be to the height of the object, as the distance of the image from the aperture is to the distance of the object from the same. To construct a permanent' Camera Obscura.-1. Darken a chamber, one of whose windows looks into a place set with various objects; leaving only a little aperture open in one shutter. 2. In this aperture fit a lens, either plano-convex, or convex on both sides, so as to be a portion of a large sphere, 3. At a due distance, to be determined by experience, spread a paper, or white cloth, unless there be a white wall for the purpose; for on this the images of the desired objects will be delineated invertedly. 4. If it be rather desired to have them appear erect, it is done either by means of a concave lens placed between the centre and the focus of the first lens ; or by receiving the image on a plane speculum inclined to the horizon under an angle of 45°; or by means of two lenses included in a drawtube, in lieu of one.—Note. If the aperture do not exceed the size of a pea, the objects will be represented, even though no lens be used. That the images be clear and distinct, it is necessary that the objects be illuminated by the sun’s light shining upon them from the opposite quarter; so that, in a western prospect, the images will be best seen in a forenoon ; an eastern pros- pect, the afternoon; and a northern prospect, about noon : a southern prospect is the least eligible of any. But the best way is to have the lens fixed in a proper frame, on the top of a building, and made to move easily round in all directions, by a handle extended to the person who manages the instrument; the images being then thrown down into a dark room imme- diately below it, upon a horizontal round plaster of Paris ground : for thus a view of all the objects quite around may easily be taken in the space of a few minutes; as is the case of the excellent Camera Obscura placed on the top of the royal observatory at Greenwich, and with a very good one made by Holroyd of Leeds, in which the images are received on a table of more than six feet diameter. A very simple portable Camera Obscura is represented in A F the annexed figure. A B C D ! Nº-9 - is a small rectangular box, TZ |\D its length being about 20 or | Gly/ "24 inches, and its breadth i £, about 10 inches. This box is closed on all sides, except the space EFG D, which is covered with a piece of ground i w glass, or transparent paper. In the other end, A B, is a moveable tube, L, with a proper lens, and E I HD is a plane reflecting mirror (set at an angle of 45°) which intercepts the rays Pp, Q q, &c. proceeding from the object PQ, which are thence reflected upon the transparent skreen EFG D, where the image of the object will be painted in its natural colours, but in an inverted position, as Q P; which, however, may be obtained erect, by the introduction of proper lenses in the tube L.-Note. That a shade is necessary to keep off the external light from the skreen EFG D, which is commonly effected by having the box covered with a hori- zontal lid, under which are two wings which open at right angles to each side of it. Various other forms are given to this instrument. º CAMP, the ground on which an army pitch their tents. The E. * Roman camp was a square, fortified with a ditch and parapet, and sometimes with walls of hewn stone, the tents themselves being formed of the same material. CAMPHORA, or CAMPHIRE, a solid concrete substance extracted from the wood of the laurus camphora, is white, pel. lucid, unctuous to the touch, of a bitter aromatic taste, and smells like rosemary. As a medicine, it is useful in fevers, and all malignant distempers. From experiments on brutes, camphire is proved to be poisonous. CAMUS, CHARLes Stephen Lewis, a celebrated French mathematician, born at Cressey in Brie, August 25, 1699; died 1768, in the sixty-ninth year of his age. - . F CANAL, an artificial cavity in the earth, filled with water, to afford an easy, speedy, and cheap conveyance of goods, &c. in boats and vessels, from one part of a country to another, 2 O 142 C. A. N. t C. A. N. I) ICTIONARY OF MECHANICAL SCIENCE, Numerous circumstances contribute, to facilitate or re- tard operations in canal-making ; as, the situation and cha- racter of the ground and country, the vicinity and connex- ion of rivers. But the great business is the construction of the Locks, or BAso Ns, lined with walls of masonry, and built where the ground is hilly. The principle of a lock is this: Suppose a declivity of 10 feet in a length of 50 yards of ground. Then we must construct a bason, with a flood-gate, so that when filled with water from above, it may permit the vessel to pass on along the upper channel of the canal. A fall of 17 feet would require two locks; a fall of 26 feet, three locks, each having 8 feet 8 inches fall. All these operations proceed on the principle of continuing levels to given points, and by arti- ficial means floating a boat some 8 feet perpendicularly, when we cannot proceed further with the level, in order that she may swim in another superior level, and vice versa. The Form of Locks, should approach as nearly as possible to the figure of the boats that are to navigate them. The width must only exceed that of the boat by a space sufficient to work the gates. A rectangle is therefore the most natural figure, because it consumes the smallest quantity of water, is filled and emptied in the shortest time, and is constructed at the least expense. The Length, Depth, and Breadth of Locks, ought also to be ‘regulated by the form of the boats, which are generally long and narrow, with flat bottoms. Narrow lock-gates are more easily worked than broad ones, and narrow boats are more easily drawn than those which are wider and shorter. Reservoirs or Basins, must be resorted to wherever a double lockage is unavoidable, from undulations in the line of naviga- tion. These basins should collect the flooded waters from an ample surface of country, and be so high as to enable all the water they contain to be drawn into the summit of the canal. They should contract towards their lower extremity, so as to require a comparatively short embankment or head, which should be placed upon a substantial foundation. Reservoirs must not leak. The dimensions of their embankments must be regulated by the nature of the materials. •.j For the theory and practice of Canal Cutting, with Plans of Locks on the most celebrated canals, see INLAND NAVIG Ation. CANAL. Embankment.—Since the pressure of any fluid is proportional merely to the depth below the surface, the strain borne by a sluice on the sides of a canal must increase uni- formly from the top to the bottom. The centre of pressure is hence not in the middle, but at one-third of the entire altitude. To this point, therefore, if more strength be wanted, the addi- tional prop should be applied. If water be confined in a canal or basin by a wall or em- bankment, the thickness of the dike must increase regularly in proportion to its depth. The adhesion of any materials, or their resistance to a horizontal thrust, may be estimated as a certain proportion of their weight, commonly the half or the third part. Let A B be the height of the wall, and make its density to three times that of water, as A B to BC, and join AC, which will represent the proper slope. If the dike be com- posed of stones or bricks, the base B C must be at least equal to the altitude A B ; but if it consists of earth, B C should be one half more. When the em- bankment is formed of earth, its side must not be perpendi- cular ; it should form an inclined plane, not exceeding 35 degrees, or the angle of repose, lest the softened parts should slide-down ; the outside, being more solid, may be steeper. The Construction of Locks or Flood Gates.—In canal naviga- tion, a boat is raised from a lower to a higher level by a series of locks, a portion of the water somewhat exceeding the length of the vessel being enclosed at the sides by walls, and at both ends by masonry, and opposite flood-gates. As soon as it passes these gates, they are shut behind it; and a small lateral or superior sluice being opened, the water rushes into the enclosure, and quickly mounts to the higher level, thus enabling the vessel again to proceed. A similar operation is performed at each successive lock. In descending the canal, the pro- cedure is exactly reversed, the water contained in the series of enclosures being allowed to flow out, and thus lower by degrees the level of the boat. The flood-gates are contrived to shut at a certain angle. If this angle be very acute, they sustain too great a pressure, and yet close feebly. Let A C and B C represent the flood-gates of a canal, which are opened by help of the extended arms A E and B F. When shut, the gate AC is pressed at right angles by the water, with a force as AC itself, which, from the principle of the lever, must exert a per- pendicular effort at the end C, as the square of A. C. The thrust thence produced in the direction A B will be as A C x C D, and will encounter an equal and opposite thrust from the gate B C. These two forces con- stitute the power which closes the gates. The force with which they are made to cohere, thus increasing with A C and CD, must augment rapidly when the angles B A C and A B C are enlarged, or their mutual inclination A C B becomes diminished. If the angle A C B were very obtuse, those conjoined gates would, like a low roof, occasion a great thrust against the walls of the canal, or the centres of the gates at A and B. 2 The thrust in the direction C A might be shown to be AºAP º It will hence be easy to determine the angle A C B, with the centres of the flood-gates which suffer the smallest strain; for >. . . A C2 e - º A C being constant, ap must be a minimum. But this quan- tity is evidently the diameter of a circle circumscribing the triangle A C B ; and since the least circle is that described about the point C, the angle A C B, at which the gates lock, should be a right angle. CAN CER, the Crab, ga, is the first of the summer signs, which the sun enters, according to the fixed zodiac of the astro- nomers, on the 21st of June, introducing the first day of sum- mer, and the longest day in the northern hemisphere, the middle of day at the north pole, and the middle of night at the south pole. Agreeably to the moveable zodiac of nature, the sun enters this sign July the 19th. The sun, on June 21st, is at his greatest north declination, and is vertical to the tropic of Cancer. The earth, at this season, has entered Capricorn, and the sun is intermediate between the earth and the Celestial Crab. And on this account the north pole, which has now its greatest inclination to the sun, enjoys perpetual day. The tropic of Cancer is in the light from 5 in the morning till 7 at night; the parallel of London from a quarter before 4 till a quarter after 8, and the polar circle just touches the dark, so that the sun has only the lower half of his disk hid from the inhabitants on that circle, for a few minutes, about midnight. Thus do we account for summer in the northern regions of the earth.-The boundaries and contents of this constellation are: on the north by Lynx, east by Leo, south by Hydra, and west by Gemini. There are 83 stars in this sign, viz. seven of the | 4th magnitude, and the remainder of inferior magnitudes. a Canceris, near the eastern extremities of the great southern claw, having 12° 34'6" north declination, and 132°9' 20" of right ascension, rises nearly E.N.E. at London, and rises and culminates as follows: Meridian Altitude, 51° 0' 6". MONTH. RISES. CULM. MONTH. | RISES. CULM. ho. mi. ho. mi. ho. mi. ho. mi. Jan. 7 14 A. | 2 0 M. July 7 0 M. 2 15 A. Feb. 4 50 A. | 11 50 A. Aug. 5 0 M. 12 10 A. Mar. 3 10 A. | 10 10 A. Sept. 3 5 M. 10 10 M. April 1 15 A. | 8 15 A. Oct. 1 15 M. 8 15 M May 11 20 M. 6 30 A. Nov. 11 25 A. 6 20 M. June 9 7 M. 4 15 M. Dec. 9 20 A. | 4 20 M. C. A N C. A N T43 DICTIONARY OF MECHANICAL SCIENCE. CANDY, or SUGAR CANDY, is sugar melted and crystallized six or seven times over, till it is rendered hard and transparent. CANES Wen Atici, the Hounds or Greyhounds, a northern constellation. These two dogs are farther distinguished by the names Asterion and Chara. CANICULAR, the name formerly given to the constellation Canis Major; and the same was also sometimes applied to the star Sirius, whence the Canicular Days. : CANicular Days, or Dog-Days, denote properly a certain number of days which precede and follow the heliacal rising of Canicular, or the Dog-star, in the morning; which were formerly the days of the greatest heat. The ancients imagined that this star, rising as above, was the cause of the hot sultry weather common at that season, as well as of the distempers which usually followed them, and somewhat of a similar notion still prevails in many of the remote parts of this country, even to the present day. The dog-days were commonly reckoned at about forty; viz. twenty before, and twenty after the heliacal rising of Sirius; and in the almanacks, were usually accounted absolutely from this circumstance, which in consequence of the precession of the equinoxes brought them into the months of June and July, instead of July and August: an alteration, however, has been made in this respect within a few years; and they are now, without any regard to the rising of Sirius, accounted from July 3 to August 11 ; these being considered the hottest days of the year. CANicular Year, denotes the Egyptian natural year; which was computed from one heliacal rising of Canicular to another. CANIS MAJOR, the Great Dog, a constellation in the heavens, is fabled to have been one of Orion's hounds; the other was Canis Minor; for Orion, Boötes, and Sagittarius were denominated Hunters annong the constellations : but some writers of ancient story tell us, that the sagacious Maera, which discovered to Erigone the burial place of her murdered father Icarius, was changed into one of the celestial dogs. The true account of Canis Major, and which has obtained the credence of mankind, is, that it represents the Egyptian god Anubis. The people of Egypt judged of the swelling of the Nile by the rising of the brilliant in this constellation, and hence they represented it by the figure of a dog, this animal being the most watchful and faithful of the brute creation. The Dog Star, Latrator Anubis, is vertical on the 30th of June, when the Nile overflows. Indeed, Canis Major seems to have had the same relation to the Nile that Cerberus had to the sun; and Porphy- ry, who was well versed in the mythology of the ancients, says, Cerberus was described with three heads, in reference to the rising, the meridian altitude, and the setting of the sun. The triple bust of the Hindu deity exhibits to us in one compound figure an hieroglyphic of the solar god, having a perfect resem- blance to Cerberus. At night, and in the west, the sun is Vish- now ; he is Brahma in the east, and in the morning ; from noon to evening he is Seeva.-The boundaries and contents of this constellation are : on the north by Monoceros, east and south by Argo Navis, and west by Columba Noachi and Lepus. In this constellation there are sixty-four stars, of which the bril- liant Sirius is of the 1st magnitude, two of the 2d, four of the 3d, four of the 4th, &c. Sirius in size and colour resembles the planet Jupiter more than any of the other fixed stars, and has thence been supposed to be nearer our earth than Arcturus, Capella, Vega, Spica, or Aldebaran. The right ascension of Sirius for 1820 was 99° 18' 10"; and the declination 16° 28′ 11." south. It rises at London on the S. E. by E. # E. point of the compass nearly ; and rises and culminates as in the following table, for the 1st of every month: Meridian Altitude 22° 9' 49". MonTH, I RISEs. CULM. MonTH. RISES. CULM. ho. mi. 'ho. mi. ho. mi. ho. mi. Jan. 7 28 A. | 1 || 49 A. July 7 18 M. 11 53 M. Feb. 5 5 A. | 9 37 A. Aug. 5 10 M. 9 22 M. Mar. 3 27 A. | 7 48 A. Sept 3 24 M. 7 54 M. April | 1 26 A. | 5 55 A. Oct. I 38 M. 6 6 M. May II 27 M. 4 4 A. Now 11 40 A. | 4 || 0 M. June || 9 27 M. 2 2 A. Dec 9 42 A. | 2 6 M. CANIS MINOR, the Little Dog, is one of the beagles in Orion's pack, or it is from the kennel of Boötes, or it is the sagacious cury'cleped Maera. The star said to be the type of Procyon, in Canis Minor, comes to the meridian about 50 mi- nutes later than Sirius, but it rises to Egypt at the same time with the brilliant in the Great Dog, but 25 degrees further east. Now, whoever attends to the observations made by the ancients upon Sirius, must be satisfied that Procyon had its boundaries assigned from its being an attendant of the Great Dog, so famous in all that regarded the rising, overflowing, and decrease of the Nile. The Egyptians have introduced the astronomical symbols in pairs; thus we have two rivers, two serpents, two bears, two fishes, &c.; and there is very strong collateral evidence to prove that their whole territory was partitioned out agreeably to those symbols. With respect to the symbol before us, there seems little doubt that Canis Minor rising in conjunction with the Great Dog, but coming later to the meri- dian, as if assigning the other the point of honour, and then declining in the west above an hour later than its companion, was a fit emblem of that fidelity which Latrator Anubis was feigned to evince towards Isis and Osiris. One of the celestial dogs may thence have reference to the arkite worship, and the other to the solar superstition.—The boundaries and contents of Canis Minor are: on the north by Gemini, east by Hydra, and south and west by Monoceros. There are fourteen stars in this constellation, according to the Britannic Catalogue, viz. one of the 1st magnitude, one of the 2d, one of the 4th, &c. a Procyonis, of the 1st magnitude, in Canis Minor, rises at London, on the east by north point of the compass nearly ; its declination north is 5° 46', and its right ascension 112° 27' 53". It rises and culminates on the first day of each month, as follows: Meridian Altitude 44' 15". Mo NTH. I RIses. CULM. Month. Rises. CULM ho. mi. ho. mi. ho. mi. ho. mi. Jan. 7 15 A. | 12 41 A. July 6 20 M. 12 50 M. Feb. 5 2 A. | 10 33 A. Aug. 4 15 M. 10 42 M. Mar. 3 15 A. 8 41 A. Sept. 2 17 M. 8 46 M. April | 12 20 M. 6 47 A. Oct. 0 30 M. 6 58 M. May | 10 15 M. 4 56 A. Nov. 10 35 A. 5 2 M. June 8 20 M. 1 2 58 A. Dec. 8 27 A. | 2 59 M. The situation of a (Procyon) is easily found when it is above the horizon at night, for it always forms a triangle with Betel- geux, Rigel, and Sirius; and it comes to the meridian about four minutes after Castor, and about one minute before Pollux. CANNON, a military engine for throwing ball, first used in the battle of Cressy, in 1346, by king Edward; or, mounted in battery on the decks of ships, to fire balls on other ships. The principal parts of a cannon are, 1st. The breech, and its button or cascabel, called by seamen the pomelion. The breech is generally understood to be the solid metal from the bottom of the concave cylinder to the cascabel, which is the extremity of the cannon opposite to its muzzle. 2d. The trunnions, which project on each side like arms, and serve to support, the cannon near the middle of its length, holding it almost in equilibrio. As the metal is thicker at the breech than towards the mouth, the trunnions are placed nearer to that end than the other. 3d. The bore or caliber is the interior or concave cylinder, wherein the powder and shot are lodged . when the cannon is charged or loaded. The entrance of the bore is called the mouth or muzzle. The other parts are as follow: The length; the 1st reinforce; the 2d reinforce; the chase; the ventfield; the chase girdle; the breech mouldings; the swelling of the muzzle; the base ring and ogee ; the vent astragal and fillets ; the 1st reinforce ring and ogee ; the 2d ditto, ditto ; the chase astragal and fillets; the muzzle ditto, ditto ; the muzzle mouldings; the swelling of the muzzle. The diameter of the ball is always somewhat less than the bore of the piece, that it may be discharged with the greater ease, and not damage the piece by rubbing it too forcibly in its passage, and the difference between these diameters is called the windage of the cannon. The length of any cannon is always reckoned from the hind part of the base ring, or begin- ning of the cascabel, to the extremity of the muzzle. The second reinforce begins at the same circle where the first ter- minates, and the chase at the same circle where the second reinforce ends. The first reinforce, therefore, includes the base ring, the ogee nearest thereto, the vent-field, the vent-astragal, and 144 C A N C A N DICTIONARY OF MECHANICAL SCIENCE. is dilated equally round its centre. * communicated to that in the piece, -immediately expands, so as to occupy a much greater space The chase comprehends the ogee nearest to the second rein- force ring ; the chase girdle and astragal, and the muzzle and astragal. The trunnions are always placed on the second reinforce, so that the breech part of the cannon may weigh something more than the muzzle part, to prevent the piece from starting up behind when it is fired. A variety of experiments made with great care and accuracy, prove that the powder, when on fire, possesses at least 4000 times more space than when in grains. Therefore, if we sup- pose that the quantity of powder with which a cannon is charged, possesses one-fourth of a cubical foot in grain, it will, when on fire, occupy the space of about 1000 cubical feet. The same experiments evince also, that the powder, when inflamed, One grain of powder fired in the centre of different concentric circles, round which grains of powder are placed, shall therefore set fire to all those grains at once. From this principle, it necessarily follows, that powder when fired in a cannon, makes at the same instant an equal effort on every part of the inside of the piece, in order to expand itself about its centre every way. But as the resistance from the sides of the piece turns the action of the powder so as to follow the direction of the bore of the cannon, when it presses upon the ball, so as to force it outwards, it presses also on the breech of the cannon, and this gives the piece a motion backwards, that is called the recoil, which is restrained by the breeching, and the convexity of the decks. The recoil in some degree diminishes the action of the powder upon the shot. But this cannot be avoided ; for if the carriages were fixed so as not to give way to this motion, the action of the powder, or the effort that causes the recoil, would tear them to pieces in a very short time. * , The metal of the cannon is not equally thick in all parts, but is in some measure proportioned to the force of the powder which it is to resist. At the breech, where the effort is strong- est, the thickness of the metal is equal to the diameter of the corresponding shot. At the first reinforce, when this begins to slacken, the thickness is somewhat less than at the breech; at the second, where the force is still further diminished, the thickness is more reduced than at the first; and by the same rule, the chase has less thickness than the second reinforce. The thickness of the chase gradually diminishes from the trun- nions to the mouth of the piece; so that if a cannon was with- out a cascabel, trunnion, and mouldings, it would exactly resemble the frustum of a cone, or a cone deprived of the small end. Cannons are charged by putting down into the bottom first a quantity of powder, one-third or one-half the weight of the ball. This is done with an instrument termed a ladle, which is a kind of cylindrical spoon, generally made of copper, and fixed to the end of a staff called its handle. Upon the powder is put in a wad of rope yarn, formed like a ball, which is pressed down upon the powder with an instrument called a rammer; upon this wad is put the ball or shot, and to secure it in its proper place, another wad is firmly pressed down upon it, which operation is called ramming home the wad and shot. The touch-hole of the piece is then filled with powder, from the upper part of which a little train is laid that communicates with it. The use of this train is to prevent the explosion of the powder from operating directly upon the instrument employed to fire the piece, which, in that case, might be forced out of the hand of the gunner. In the modern pieces, a little gutter or channel is framed on the upper part of the breech, to prevent the train from being dispersed by the wind. This channel reaches from the touch- hole to the base ring. - The cannon being pointed to its object, or the place it is intended to strike, the train is fired, and the flame immediately conveyed to the powder in the touch-hole, by which it is further The powder being kindled, than when in grains, and thus dilated, it makes an effort on every side to force itself out. The ball making less resistance than the sides of the piece, upon which the powder presses at the same time, is driven out by its whole effort, and acquires first reinforce ring. The second reinforce contains the ogee I that violent motion which is well known to the world. After next to the first reinforce ring, and the second reinforce ring. firing, there is a sponge used to clean the piece, and extinguish any sparks that may remain behind. In the land service, the handle of the sponge is a long wooden staff; but in ships of war, this handle, which usually contains the rammer at its other end, is a piece of rope well stiffened by spun-yarn, which is for this purpose firmly wound about it. By this convenience the rammer becomes flexible, so that the piece is charged within the ship, as the person who loads it may bend and accommo- date the length of the rammer to the distance between the muzzle and the ship's side; being at the same time sheltered from the enemy’s musketry, to which he would be exposed, in using a wooden rammer without the ship. To sponge a piece, therefore, is to introduce this instrument into the bore, and thrusting it home to the further end thereof, to clean the whole cavity. - - - The worm, of which there are different kinds, is used to draw the charge when necessary. The bit, or priming-iron, is a kind of large needle, whose lower end is formed into a gimblet, serving to clear the inside of the touch-hole, and render it fit to receive the prime. The lint-stock is a kind of staff, about three feet long, to the end of which a match is occasionally fastened to fire the piece. * - The following is Mr. Robin's scheme for augmenting th force of the present sea-batteries, on this plain principle—that all ship-guns should be cast upon the model of the 32-pounders, measuring by the diameter of the respective bullet; so that for each pound of bullet there should be allowed one hundred, and two-thirds of metal only. The advantages of this scheme will appear by the following comparison of the weight of the present pieces, with their weight proposed by this new fabric. Pounders. Weight now in Hundreds. Weight by New Fabric. 24 . . . . . . . . . . . . 48 to 46 . . . . . . . . . . . . . . . . . . 40 18 . . . . . . . . . . . . 41 to 39 . . . . . . . . . . . . . . tº e 30 12 . . . . . . . . . . . . 34 to 31 tº e º O e º e º e s e - e. e. 20 9 . . . . . . . . . . . . 29 to 26 . . . . . . . . . Q tº e º e s e º e 15 6 . . . . . . . . . . . . 34 to 18 . . . . . . . . . . . . . . . . . 10 Hence it appears that the 24-pounders will be eased of 6 or 8 cwt. of useless metal; and instead of guns of inferior caliber now used, much larger ones of the same weight may be borne, especially when it is remembered that this computation exceeds even the present proportion of the 32-pounders; so that from the above projected 18-pounders, for instance, 2 or 300 weight may be safely taken. The changes then proposed by the author are these :— Pounders. Hundreds. Pounders. Hundreds. . r. (; "...º sº, ºft.*... ; 12 . . . . . . 34 and 31 ( W 24 ...... º e > - 40 18 . . . . . . 41 and 39 -- . . . . . . . . . . - The nine-pounders lately cast, being still lighter than what is here represented, they may, perhaps, be only transformed into 12-pounders; but this will be a very great addition of strength, and the 12-pounders thus borne, will be considerably lighter than the smallest nine-pounders now in use. The weight of the present three-pounders is not remembered exactly by the author, but he doubts not that they are heavier than the pro- posed six-pounders, and may therefore be changed for them. And the author believes, that one-fourth or one-fifth of the weight of the bullet in powder, if properly disposed, is abund- antly sufficient for every species of ship's guns. & Boring of CANNoN. (See the Plate.)—Till within a few years, iron cannon were cast with a cylindrical cavity, nearly of the dimensions of the caliber of the piece, which was after- wards enlarged to the proper caliber by means of steel-cutters fixed into the dog-head of a boring bar-iron. Three equidis– tant side-cutters were requisite to preserve the caliber straight and cylindrical ; and a single cutter was used at the end of the bar to smooth the breech of the piece. In boring cannon cast hollow, the piece was fixed upon a carriage that could be moved backwards and forwards in a direct line with the centre of a water-wheel; in this centre was fixed the boring-bar, of a suffi- cient length to reach up to the breech of the piece, or more pro- perly to the further end of the caliber. The carriage with the piece being drawn backwards from the centre of the water- C A N . G. A. O 145 DICTIONARY OF MECHANICAL SCIENCE. wheel to introduce the boring and finishing bars and cutters, -it is then pressed forwards upon this bar by means of levers, weights, &c. and the water-wheel being set going, the bar and fullers are turned round, and clean out and smooth the caliber to its proper dimensions. - Experience at last pointed out many inconveniences arising from the method of casting guns hollow, and widening the calibers by boring bars; but chiefly, that all guns cast hollow became more or less spongy where they ought to have been most compact; and numberless cavities also were created round the cores, from stagnated air generated in them, which were too deep to be cut out by the boring. To remedy these defects, iron cannon as well as brass is now universally cast solid, by which means the column of metal is greatly enlarged, afid the grain more compressed; and the contraction becomes in the heart of the column, and consequently is cut out by the perforation for the caliber, Guns are bored out of the solid reversely from the hollow method. The piece A is placed upon two standards BB, by means of two journeys, turned round by machinery; the breech D being introduced into the central line of the wheel, with the muzzle towards the sliding carriage E, which is pressed forwards by a ratch F, and weights, in the same way as the gun carriage was in hollow-boring. Upon this sliding carriage is fixed, truly horizontal and central to the gun, the drill-bar G, to the end of which is fixed a carp's-tongue drill or cutter H ; which, being pressed forward upon the piece whilst it is turn- ing round, perforates the bore, which is afterwards finished with bars and cutters as the hollow guns were. The machinery for boring of ordnance is sometimes put in motion by a steam-engine; and in this way, from 18 to 24 great guns have been boring at the same time; the borer in each piece being brought up to its proper place in the gun, by a lever and weights. In this method of bringing up the borer, the pressure may always be made equable, and the motion of the borer regular; but the disadvantage is, that without due attention, the borer may work up too far towards the breech, and the piece be spoiled. - “In the Royal Arsenal at Woolwich,” says Dr. Gregory, “ only one piece is bored at a time in the same mill: the gun to be bored lies with its axis parallel to the horizon, and in that position is turned round its axis by means of wheel-work, moved by one or more horses. The borer is laid, as above described, in the direction of the axis of the gun, and is incapable of motion in any direction except that of its length ; and in this direction it is constantly moved by means of a small rack-wheel, kept in proper motion by two men, who thus make the point of the borer so to bear against the part of the gun that is boring, as to pierce and cut it. The outside of the gun is smoothed at the same time by men with instruments fit for the purpose, whilst it turns round, so that the bore may be exactly in the centre of the metal. In this way the boring is performed with great nicety, the guns scarcely ever failing in the examination. But in these mills the horses work to great disadvantage, the diameters of the walks in which they move being far too small.” See GUN, Powder, GUNNERY. CANNONADE, the application of artillery to the purposes of war, directing the shot against some remote object, as a ship, a fortress, &c. which it is designed to destroy or capture. In the marine, a large vessel may be considered as a combi- nation of floating batteries, and hence, her efforts must be greatly superior to those of a fortress on land; but this is not always the case, for on some particular occasions her situation may be extremely dangerous, and her cannonading ineffectual. There are several circumstances in which her superiority con- sists, viz. the power of bringing her different batteries to con- verge to one point; of shifting the line of her attack so as to do the greatest possible execution against the enemy, or to lie where she will be the least exposed to his shot; and chiefly because, by employing a much greater number of cannon against a fort than it can possibly return, the impression of her artillery against stone walls soon becomes decisive and irre- sistible. Besides these advantages in the attack, she is also greatly superior in point of defence; because the cannon shot passing with rapidity through her sides, seldom do any execu. tion out of the line of their flight, or occasion much mischief by their splinters; whereas, they very soon shatter and destroy the faces of a parapet, and produce incredible havock annongst the men by the fragments of the stones, &c. A ship may also retreat when she finds it too dangerous to remain longer exposed to the enemy's fire, or when her own fire cannot pro- duce the desired effect. Finally, the fluctuating situation of a ship, and of the element on which she rests, render the efforts of shells very uncertain, and altogether destroys the effect of the ricoshet or rolling and bounding shot, whose execution is so pernicious and destructive to a fortress in land engage- ments ; both of which, however, a ship of war may apply with great success. On the contrary, the chief inconvenience to which she is exposed, is, that the low-laid cannon in a fort, near the brink of the sea, may strike her repeatedly on or under the surface of the water, so as to sink her before her cannonade can have any considerable efficacy. • . CANOE, a sort of Indian boat, or vessel, formed of the trunk of a tree hollowed, and sometimes of several pieces of the bark fastened together; they are used on various occasions, as fishing, passage, trade, &c. and are of several sizes, according to the different uses for which they are designed in different countries. They are generally rowed with paddles, instead of oars, which are pieces of light wood, nearly resembling a gorn Shovel, and instead of moving the paddle horizontally like an oar, they row perpendicularly ; the small ones are very nar- row, having only room for one person in breadth, and eight or ten lengthways. They very easily carry sail, unless when going before the wind, and their sails are made of a sort of rushes or silk grass; they seldom have any rudder, the want of which is supplied by a dexterous management of the hind oars. The Indians who navigate them are very expert in rowing uniformly, and in balancing them properly with their bodies, which would be difficult for a stranger to do, however well accustomed soever to the conducting of our boats, on account of the extreme lightness of the canoes, and their aptness to be overturned. The Negroes in Guinea, and even many in the East Indies, use them. The American Indians, when they are necessitated to land on account of a waterfall or other occa- sion, carry their canoes on their heads or shoulders, till they arrive at some place where they may again be launched. The canoe of the Esquimaux Indians in Labrador has a light wooden frame, and the shell, instead of a plank, is made with Seal skins sewed together, which are not only extended round the bottom and sides, but likewise over the top, forming a complete deck, and having only one opening conveniently framed, and situated to admit the Indian into his seat. A flat hoop is fitted to this hole rising about four inches, to which the surrounding skin is sewed. The Indian’s calf-skin jacket being of a proper length, he can occasionally bind the skirt of it round the outside of this hoop, by which means he keeps the canoe free from water, and is enabled to pursue his game far from land, and in stormy seas. His paddle is about 10 feet long, light, and flat at each end, with which he both rows and steers with great velocity and exactness. CANON, in Arithmetic, Geometry, &c. a general rule for resolving all cases of the same kind ; this word is now seldom used ; we say instead of it, method or formula. CANT TIMBERs, those timbers which are situated at the two ends of a ship. They derive their name from being canted or raised obliquely from the keel, in contradistinction to those whose planes are perpendicular to it. The upper ends of those on the bow or fore part of the ship are inclined to the stem, as those in the after or hind part incline to the stern-post above. CANTATA, in Music, a song or composition intermixed with recitatives, airs, and diſſerent movements, chiefly intended for a single voice. - CANVASS, a strong kind of cloth, of which the sails are made. Among Painters, canvass is the cloth on which they usually draw their pictures, having first stretched it in a frame of deal wood. . . - - CAOUTCPHOUC, elastic resin, or Indian rubber, a sub- stance produced from an American tree, has been already explained. This substance oozes out of the trees by inci- sions made in them, and has the appearance of milk, and it is thickened merely by exposure to the air. - CAoutchouc Gum is thus made;—Take one pound of spirit 2 P - i46 C A P C A P DICTIONARY OF MECHANICAL SCIENCE. ºf turpentine, and one pound of the gum, cut into small pieces. A knife dipped in cold water cuts this elastic stuff easily.) Pbur the turpentine into a long-necked matrass, or fire-proof bottle, which must be placed in a sand bath; throw in the gum, bit by bit, till it all dissolves. Add now a pint of nut or linseed ëil, or oil of poppies; then let the whole boil for a quarter of an hour, and the preparation is finished. This is an excellent but expensive varnish for air-balloons. CAP, a strong thick block of wood, having two large holes thröugh it, the one square, the other round, used to confine two masts together, when one is erected at the head of the 6thér, in order to lengthen it. The principal caps of a ship are those of the lower masts, which are fitted with a strong eye-bolt on each side, wherein to hook the block by which the topmast is drawn up through the cap. The breadth of all the caps is equal to twice the diameter of the topmast, and the length to twice the breadth. The thickness of the main and forecaps is half the diameter of their breadths; the mizencap three-sevenths, and the topmast caps two-fifths of their respec- five breadths. In the same manner as the topmast slides up through the cap of the lower mast, the top-gallant-mast slides up through the cap of the topmasts. CAPILLARY Action. The suspension of a slender column of water in the interior ring of a glass tube, is the popular explanation of capillary action, or attraction. CAPILLARY Tubes. One of the most singular phenomena of these tubes is, that if you take several of them of diſferent sizes, open at both ends, and immerse them a little way into water, or any other ſluid, it will immediately rise in the tubes to a considerable height above the surface of that into which they are immersed ; these heights varying nearly in a recipro- cal proportion of the diameters; the greatest heights, according to Dr. Hook, being about 21 inches. The heights, however, are not the same for all fluids, some standing considerably higher or lower than others: and with regard to quicksilver, it does not rise in their tubes at all, but, on the contrary, stands lower in the tube than in the vessel into which the tube is immersed, and that so much the more as the diameter is smaller. Another phenomenon of these tubes is, that such of them as will natu- rally discharge water only by drops, when electrified yields it in a perpetual stream. Various bypotheses have been advanced to account for the ascent of fluids in capillary tubes; some attributing it to the attraction of the glass upon the upper sur- face of the fluid, others again, to the diminished pressure of the air on the fluids in the tube, &c. The cause of the pheno- menon is satisfactorily accounted for thus: It is a fundamental property of fluids, that any force impressed in one direction may be propagated equally in every direction. The tendency of the fluid, then, to approach the glass, will occasion it to spread over the internal cavity of the tube, and consequently to mount upwards. - - s Capillary action is not confined to glass tubes, but is exerted among all substances perforated by pores, or subdivided by fissures or interstices. of plants and animals; the ascent of humidity through rocks, earth, &c.; the ſymph or perspiration exuded by the pores of the human skin, the leaves of trees, plants, and grasses—pores that exceed not the ten-thousandth part of an inch: and while plants retain their vegetating principle, the humidity they draw from the earth by means of their roots, is constantly exhaled into the atmosphere, and as constantly supplied by the ascent of sap from the roots. CAPRA, the name of a small Northern Constellation, con- sisting of three stars. CAPRICORN, the Goat, a southern constellation, and the tenth sign of the zodiac, denoted by the character wº, being intended for the representation of the goat's horns. It is the first of the winter, and the fourth of the southern signs, accord- ing to the fixed and intellectual zodiac ; and the sun enters it on the 21st of December, which is the time of the winter sol- stice, when the earth makes the transit from Gemini to Cancer. But the visible and moveable zodiac places this sign in the station of Aquarius, and the sun enters it about the 16th of January. At the period of the winter solstice, the sun being vertical to the tropic of Capricorn, the southern hemisphere enjoys the same light, &c. which the northern hemisphere Hence, the excretory vascular systems | enjoyed on the 21st of June, when the sun was vertical to the tropic of Cancer. It is then the middle of day at the south pole, and the middle of night at the north pole.—The bounda– ries and contents of Capricorn are: on the north and east of Antinous and Aquarius, on the south by Piscis Australis, and on the west by Sagittarius. It contains 51 stars, three of which are of the 3d magnitude, three of the 4th, &c. The following table shews the time when a, a star of the third mag- nitude, in the Goat's forehead, rises and culminates for the first day of each month in the year. This star rises nearly ot the E. S. E. H. E. point of the horizon, at London; its right ascension is 302° 0' 51", and its declination 13° 5' 39" south : Meridian Altitude 25°23'21". MONTH. RISEs. CULM. MONTH. RISES. CUL.M. º. ho. mi. ho. mi. ho. mi. ho. mi. Jan. 8 30 M. I 25 A. July 8 37 A. | I 30 M. Feb. 6 14 M. 1 1 1 0 M. Aug. 6 40 A. | 11 25 A. Mar. 4 25 M. 9 20 M. Sept. 4 45 A. 9 30 A. April 2 30 MI. 7 20 M. Oct. 2 58 A. | 7 40 A. May 12 45 M. 5 30 M. Nov. 1 0 A. | 5 45 A. June 10 35 A. 3 28 M. Dec. 10 45 M. 3 45 A. Tropic of CAPRico RN, a small circle of the sphere parallel to the equinoctial, passing through the beginning of Capricorn, or the winter solstice, or point of the sun's greatest southern declination. CAPRIOLES, in the Manage, leaps which a horse takes in the same place without advancing, in such a manner, that when he is at the height of the leap, he jerks out with his hinder legs even and near. The common name of this exercise is, among dragoons, the pillared horse, because the animal, to work well at caprioles, is put between two pillars, and taught to raise first his fore quarters, and then his hind quarters, while his fore ones are yet in the air. g CAPSTAN, or CAPstern, cº tº: hº º ºš .# º ==º | f hape O 3. COR16 U.SUla . ." ºš \\ * 5 © - y º placed behind the windlass Eº §S. - Sºssº º of a ship, to weigh anchors, hoist up or strike down top- masts, strain ropes, or heave any heavy bulky thing on board of a ship, as in the upper figure. The advantages of simpli- fying machinery are well ex- emplified in the second cap- stan, which unites great strength and simplicity. It is represented in the low- er figure, where A D is a compound barrel com- posed of two cylinders of different radii. The rope D E C is fixed at the extre- mity of the cylinder D; and after passing over the pulley E, which is attached to the load by means of the hook F, it is coiled round the other cylinder D, and fixed at its upper end. The cap- stan bar A B urges the compound barrel C D about its axis, so that while the rope coils round the cylinder b it unwinds itself from the cylinder C. Let us suppose, that the diameter of the part D of the barrel is 21 inches, while the diameter of the part C is only 20 inches, and let the pulley E be 20 inches in diametcr. . When the barrel A jo, therefore, has performed one complete revolution by the pressure ex- erted at B, 63 inches of rope, equal to the circumference of the cylinder, will be gathered upon the cylinder D, and 60 inches will be unwound from the cylinder C. The quantity of wound rope, therefore, exceeds the quantity that is unwound by 63 – 60 = 3 inches, the difference of their respective peri- meters; and the half of this quantity, or 1% inches, will be the He Illilill ~- Sºº-E: g º | { # º | # | ; | space through which the load or pulley E moves by one turn °C A R C A R Diction ARY OF ME&HANICAL science. T47 of the bar. . If a simple capstan of the same dimensions had been employed, the length of rope coiled round the barrel would have been 60 inches; and the space described by the pulley, or load to be overcome, would have been 30 inches, Now, as the power is to the weight as the velocity of the weight is to the velocity of the power, and as the velocity of the power is the same in both capstans, the weights which they will raise will be as 1} to 30. If it be wished to double the power of the machine, we have only to cover the cylinder C with lathes a quarter of an inch thick, so that the difference between the radii of each cylinder may be half as little as before ; for it is obvious that the power of the capstan increases as the dif- ference between the radii of the cylinders is diminished. As we increase the power, therefore, we increase the strength of our machine, while all other engines are proportionably enfeebled by an augmentation of power. Were we, for exam- ple, to increase the power of the common capstan, we must diminish the barrel in the same proportion, supposing the bar A B not to admit of being lengthened, which will not only diminish its strength, but destroy much of its power by the additional flexure of the rope.—This capstan may be easily converted into a crane, by giving the compound barrel a liori- zontal position, and substituting a winch instead of the bar AB. The superiority of such a crane above the common ones does not require to be pointed out; but it has this additional advantage, that it allows the weight to stop at any part of its progress, without the aid of a ratchet wheel and catch, because ihe two parts of the rope pull on the contrary sides of the barrel. The rope indeed which coils round the larger part of the barrel acts with a larger lever, and consequently with greater force, than the other; but as this excess of force is not sufficient to overcome the friction of the machine, the weight will remain stationary in any part of its path. The principle on which the preceding capstan is constructed, might be applied with great advantage when two separate axles A C, B D are driven by means of the winch H and the wheels B and A, as in the annexed figure. It is evident, that when the winch is turned round in one direction, the rope r is unwound from the axle B D ; the wheel B drives the wheel A, so that the axle A C moves - in a direction opposite to that of B D, and the rope is coiled round the axle A C. If the wheels A, B, are of the same diameter and the same num- her of teeth, the weight W will be stationary, as the rope wound about one axle will be always equal to what is un- wound from the other. If the wheels have different diame- ters, or different numbers of teeth, the quantity of rope • º wound round the one axle will exceed what is unwound from the other, and the weight will be raised. CAPUT DRAco Nis, the Dragon's Head, a name given by some to the star a, Draconis, in the head of that constellation. CARDAN, JeroM, a celebrated mathematician, physician, and astrologer of the sixteenth century, born in Italy Sept. 24, 1501, and died at Rome in Sept. 1575. As an astrologer, he was invited to England in order to cast the nativity of Edw. V. as he had already done that of his own ; which latter not being precisely correct as to the time of his death, he is said to have starved himself for the honour of the science; viz. that his living might not discredit his art. Hudibras alludes to Car- dan’s pretended astrological skill in the following lines:— “Cardan believes great states depend Upon the tip of the Bear's tail's end ; And as she wisks, it tºwards the sun, Strews mighty empires up and down.” CARDINAL Points, in Geography and Navigation, the four principal points of the compass; viz., east, west, north, and south. The term is derived from cardo, a hinge, being that on which all the others turn or depend. CARDINAL Signs, are those at the four quarters, or the equi- | noxes and solstices; viz. the signs Aries, Libra, Cancer, and Capricorn. Cardinal Winds, those that blow from the cardinal oints. . - p CARDIOIDE, (see the annexed figure,) 9-sº-g the name of a curve so denominated by C/ >ks: Castilliani, from its resemblance to a Q Q heart, kapóla : the construction of which is as follows:—Through one extremity A, of Lºr the diameter A B, of the circle A P B, B draw a number of lines A PQ, cutting the - Q circle in PP, &c. upon the set off PQ, equal to the diameter AB; then the curve passing through all the points Q, Q, &c. is termed the Cardioide. From this generation of the curve, is readily reduced its principal properties; viz. that - A B every where . . . . . . . . . . . . . . P Q - A C Q or Q Q = A a = 2 AB A Q – A B =E A P P always bisects Q Q. CAREENING, the operation of heaving a ship down on one side, by the application of a strong purchase to her masts, which are properly supported for the occasion, to prevent their breaking with so great a strain; by which means one side of the bottom, being elevated above the surface of the water, may be cleansed or repaired. When a ship is laid on a careen every thing is taken out of her ; but this operation is now nearly superseded by sheathing the ships with copper, whereby they keep a clean bottom for several years. A ship is also said to careen, when she inclines to one side at sea by a press of sail. - - - CARLINGS, short pieces of timber ranging fore and aft from one deck beam to another, into which their, ends are mortised ; they are used to sustain and fortify the smaller beams of the ship. - - 4. CARMINATIVES, Medicines used in colics, or other flatu- lent disorders, to dispel wind. CARMINE. See Colour MAKING. -- CARNATION, or Clove Pink, an agreeable flower, valued for its pleasant flavour and lovely leaves. It is said the flowers of this plant, reduced to a decoction, have cured many malig- nant fevers, &c. CARNELIAN, in Natural History, a precious stone, red, yellow, or white, usually brought from the East Indies. CAROTIDS, in Anatomy, two arteries of the neck, which convey the blood from the aorto to the brain; one called the right, and the other the left carotid. CARPENTER, a person who practises carpentry. CARPENTER of a ship, is an officer appointed to examine and keep in order the frame of the ship, together with her masts, yards, boats, and all other wooden machinery, likewise the stores committed to him by indenture from the surveyor of the dock yard. It is the carpenter's duty in particular, to keep the ship tight, for which purpose he ought frequently to review the decks and sides, and to caulk them when it is found necessary. In the time of battle, he is to examine up and down with all possible attention in the lower apartments of the ship, to stop any holes that may be made in the sides by shot, with wooden plugs, provided, of several sizes for that purpose. CARPENTRY, the art of building, framing, &c. See Joi NER. CARRIAGE of a Gun, is a strong frame of wood fixed on four solid wheels, or trucks, on which the cannon is placed: its chief parts are as follow :—1. The sides or cheeks; 2. the axletrees; 3. the trucks or wheels; 4. the transom ; 5. the sole or bottom; 6. the bed; 7. the quoin. These are all of wood. 8, the cap-squares, or clamps; 9, the eye-bolts; 10. joint bolts ; 11. the transom bolt; 12, the bed bolt; 13, hind axletree bolts; 14. the breeching bolts; 15. loops, or eye- | bolts, to which the gun tackle are hooked; all of iron. The Construction of Wheel Carriages is one of the most im- portant branches of mechanical science, whether we consider their general use, or the numerous lives which are daily risked in travelling by this mode of conveyance. We will, therefore, in the first place, direct our readers' attention to the wheels of these vehicles. Every wheeled carriage consists of two or more wheels, generally four: but the fore wheels of our wag- I48 , O A. R. C. A. R. DICTIONARY of MECHANICAL screNCE. gons are unaccountably small, and it is not uncommon to see carts moving upon wheels scarcely two feet diameter. We know that the convenience of turning is urged as the reason for diminishing these wheels, and we allow, that much address is requisite in the crowded and narrow lanes and courts of London, to turn unwieldy waggons, drawn by four huge horses. The disadvantages of small wheels will be obvious from this : Suppose CD E (as in the annexed figure,) a wheel, and FG an obstacle over which it is to be moved by a force P, acting in the direction ** /~ ID A H ; join A F, and draw F m, F n, perpendicu- lar to C A and A H. The weight D of the wheel is evidently the weight to be rais- ed, and may be represented by W acting at the point A in the vertical direc- tion A. C. We. may now consi- der A F as a le- * ver, whose fulcrum is F, and there will be an equilibrium when the force P is to the force W, as the perpendicular F n is to the perpendicular F m. And since F m represents the mechanical energy of the power P to turn the wheel round F, it is obvious, that when FG is equal to the radius of the wheel, (as in this case it is only 12 inches,) the weight P, however great, has no power to move it over the obstacle, for when FG is equal to A C, F m will vanish, that is, the obstacle being as high as the axletree of the wheel, it could never surmount it. In other words, Fm is now equal to O, which, if multiplied by P. no matter what the weight of P may be, the product is O. How very difficult then must it be for the best horses to tug an unwieldy waggon with fore wheels only 14 inches diameter. Hence, since the power of a wheel to overcome stones, rub- bish, and all manner of resistances in the road, increases with * % * / its diameter, the advantages of large wheels for overcoming || such resistances must be apparent. But there are some cir- cumstances, which, independent of their weight and expense, prescribe limits to the size of wheels. A wheel should never exceed 44 feet diameter, that is, the height of a horse's shoulder where the traces are fixed to the collar. With respect to the shape of the wheels, every mechanic would place the spokes perpendicular to the axletree, if he were not prejudiced, by apprenticeship, to the pretended advantages of concave or dishing wheels, or those which have inclined spokes, as in the annexed figure, PA, PB, and coni- cal rims A r and Bs. It is alleged, this wheel renders the car- riage less liable to be overturned, by extending the base ; that it is stronger; that it hinders the fellies //71. A from rubbing against the sides of the cart, &c. &c. But the concave dishing wheel is more expensive than the other, more inju- rious to the roads, more liable to be broken by accidents, and less durable than the wheel with spokes perpendicular to the naves. Look at the figure, and you will see that the whole of the pressure which the wheel A B sustains, is exerted along the ºftºs, inclined spoke, Ps therefore acts obliquely É upon the level ground n D, whether the #º: rims with their tire irons are conical or cylindrical. But when the spokes are per- pendicular to the nave, as pn, and when the rims m A., n B, are cylindrical, and parallel to the ground, the weight sus- tained by the wheel acts perpendicularly upon the road, and whatever shocks it may receive from resistances, fall upon its strongest position, where it is in no danger of giving way to the strain, sºº The Position of Hºheels.--All wheels should revolve on per- fectly straight axletrees, and be themselves perfectly parallel or perpendicular to the road. By this method there is the least stress in all given cases on the linch-pin, the axles, the spokes, and rim; and the friction less than in the conicawheels, which partly roll and partly drag. º On the Line of Traction, and the Method by which Horses exert their Strength.-In all four-footed animals, the hinder feet become the fulcrum of the lever by which their weight acts against the load; and when the animals pull hard, they depress their chest, and thus increase the ſever of their weight, and diminish the lever by which the load resists their efforts; for it is a general law, that animals draw by their weight, and not by the force of their muscles. So that when a horse is employed in drawing, his effort will depend, in some measure, both upon his own weight and that which he carries on his back. Indeed it is highly useful to load the back of a drawing horse to a certain extent; though this, on a slight consideration might be thought to augment unnecessarily the fatigue of the animal : but it must be considered, that the mass with which the horse is charged vertically is added in part to the effort which he makes in the direction of traction, and thus dispenses with the necessity of his inclining so much forward as he must otherwise do; and may, therefore, under this point of view relieve the draught more than to compensate for the additionai fatigue occasioned by the vertical pressure. Carmen, and waggoners in general, are well aware of this, and are commonly very careful to dispose of the load in such a manner that the shafts shall throw a due proportion of the weight on the back of the shaft horse. The best disposition of the traces during the time a horse is drawing, is to be perpendicular to the position of the collar upon his breast and shoulders: when the horse stands at ease this position of the traces is rather inclined upwards from the direction of the road; but when he leans forward to draw the load, the traces should then become nearly parallel to the plane over which the carriage is to be drawn; or, if he be employed in drawing a sledge, or any thing without wheels, the inclina- tion of the traces to the road, supposing it to be horizontal should be about 1839. t y From the preceding observations, it will be easy in most cases to adapt the size of the wheels to that of the animal which is to draw in the shafts, so that when he leans forward to his work, the traces may be nearly parallel to the road, whether that road be horizontal or not; always recollecting, that, if there be any variation from the parallel position, it must be rather inclining upwards than downwards; as the former will somewhat diminish the friction, while the latter, instead of raising the wheels from any hollow into which they may fall, will tend to draw them down lower, and much increase the labour of the animal. When several horses are harnessed one before another, so that they may all draw at the same load, and the slope on which they are drawing changes, as from D A to A B, (see the engraving in the next page,) the effort of the horse which draws along the road A B is decomposed into two parts, of which one tends to pull up the load, the other to pull down the horse which is in the shafts and is drawing along the slope D A. This latter composant is always greater as the traces of the foremost horse are the longer. From the point E where the traces are fastened to the horse next the load, draw ER to the same point in the second horse R, and let R be another posi- tion of the second horse; it is required to find the difference of effect that will be produced by placing the second horse at R. or at R', or the comparative advantages of short and long traces. From R', the point where the traces are fixed, draw R'F' E ; and from E draw E m n parallel to the declivity D A. Take EF = EF" to represent the power of the horse in the direction of the traces, which will be the same whether he is . yoked at R or at R'; draw E A perpendicular to D A, F n, F'm parallel to E A, and Fø, F'f parallel to E m. Then since the second horse when at R pulls with a force represented by FE, in the direction FE, we may resolve this force into the two forces En, E 6, one of which En is solely employed in dragging the cart up the inclined plane DA, while the other Eq. is solely C A R C A R. Diction ARY of Mâch ANICAL scIENCE. T49 employed in pressing the first horse E to the ground. Let the horse be now removed from R to R', the direction of the traces becomes R. F. E, and F' E = F E is the power exerted by the horse at R', and the direction in which it is exerted. But this force is equivalent to the forces Em, Ef, the first of which * acts directly against the load, while the other presses the horse against the ground. Hence we see the disadvantages of long traces, for the force which draws the load when the horse is at Rſis to the force when the horse is at R, as Em to E m, and the forces which press the horse upon the ground as Ef to E 4, ... , , , or as Fºm to F m. Now E º = F n = FE x sin. n EF; hence - F 4 = FE x sin. (n E7 - FE3’) (g'E being paralleLtd A B') and En = E F x cos. (n Eg' – F Eg'). In like manner we have E f- FE x sin. (n Eg' – F Eg'), and E m = E F x - R cos, (n Eg' – F. Eg'). Now sin. FEg' = sin. FE g = #. º R! g’ R g / --! w and sin. F Eg' = ERA = ER, ; but R g = R'g' = B R — EQ = B R – B R x cos. n Eg' – B R × (1 — cos. m. Eg). By substituting this value in the equations which contain the values of Eq., Em, Ef, E m, and considering that the angles F Eg', F. Eg', are always so small that their arcs differ very little from their sines, we have BR × 1 — cos. m. E FEg = X R. R. 4, an E R! By substituting these values in the preceding equations, we have B R × 1 — cos. m. E E F x sin. (n E 9 – X cos. n tº g, E p = E R. te B R × 1 — cos. m. E & Ef n = E F x sin, (n Eg — E Rſ 5 Tº R × 1 — cos. m. E E n = EF x cos. (n Eg — E. R. 2, - B R x I — cos. m. E . E m = E F x cos. (n E9 — E R' tºg Suppose A B horizontal, the ascent D C A, that for every 6 feet, as C N in a horizontal plane, the vertical rise N A should be one foot; this slope is too steep for any common road, but may sometimes be met with in ascents from stone quarries, gravel pits, &c. In this case, the angle m Eg will be nearly 9° 28′, which, expressed in decimal parts of the radius, gives sine 0-16522, and cos. n E g = 0.98638. Then if E F = 200 lbs. B R = 3, feet, ER = 8 feet, ER = 12 feet. Then shall we have, & s r. g (1) .... F q = 200 sin (0.16522 – “H”) - = 200 sin. 9° 7' 29" = 31-716 lbs. (2) .... F4 = 200 sin. (0.16522 – “Hºº) – 200 sin. 9° 14'29" – 32'25 lbs. (3) .... E q = 200 cos. 9° 7'29" = 177,47 Ibs. (4) . . . . E q = 200 cos, 9° 14'29" = 197.404 lbs. Hence it appears, that the horse whose breast is at E is pulled downwards by the other horse, with a force equivalent to about 321bs: this weight is small for a horse that is not fatigued ; but we should consider, that when drawing up a steep road the animal's strength is much weakened, so that it 17. a FEg' = BR × 1–cos. m Eg . may be obliged to yield to a very small effort. A lengthening of four feet to a trace of eight feet, will produce an augmenta- tion of 32.25 – 31-716 – 0.534 lbs. in the effort which tends to pull the shaſt horse down, and a diminution of 197°47 – 197'404 = 0.066 lbs. in the effort which raises the load up the hill. These quantities are not considerable; but it appeared desirable to explain the method of ascertaining their magnitude. And it may be added, that when a horse pulls for only a short time, as a few, minutes, he will often exert a force equivalent to 500 or 600 lbs. : in which case, the tendency to pull down a shaft horse rising a hill would be thrice as much as we have stated it above; a force against which no horse could stand in such a disadvantageous position. On the Position of the Centre of Gravity, and the manner of .* disposing the Load.—If the axletree of a two-wheeled carriage pass through the centre of gravity of the load, the carriage will be in equilibrio in every position in which it can be placed with respect to the axletree; and in going up and down hill the whole load will be sustained by the wheels, and will have no tendency either to press the horse to the ground, or to raise him from it. But if the centre of gravity is above the axle- tree, as it must necessarily be, according to the present con- struction of wheel-carriages, a great part of the load will be thrown on the back of the horses from the wheels when going down a steep road, and thus tend to accelerate the motion of the carriage which the animal is striving to prevent; while, in ascending steep roads, a part of the load will be thrown belind the wheels, and tend to raise the horse from the ground, when there is the greatest necessity for some weight on his back to enable him to fix his feet in the earth, and overcome the great resistance which is occasioned by the steepness of the road. On the contrary, if the centre of gravity is below the axle, the horse will be pressed to the ground in going up hill, and lifted from it when going down. In all these cases, therefore, where the centre of gravity is either on the axletree, or directly above it or below, the horse will bear no part of the load on level ground: in some instances he will be lifted from the ground, when there is the greatest necessity for his being pressed to it, and he will sometimes bear a great proportion of the load, when he should rather be relicved from it. The only way of remedying these evils, is, to assign such a position in the centre of gravity, that the horse may bear some portion of the weight when lae must exert great force against the load, that is, in level ground, and when he is ascending steep roads; for no animal can pull with its greatest effort, unless it is enabled to use its feet as levers upon the ground as a prop or fulcrum. This may be effected in the following manner:—Let C D E (last figure but two) be the wheel of a cart, A H one of the shafts, H that part of the shaft by which the cart is suspended over the horse’s back, A the axletree ; then if the cart and the load together weigh 400 lbs, if the distance A H be 8 feet, and if the horse should bear 50 lbs of the weight, then b A should be one foot, which being one-eighth of A H, will make the pressure 2 Q 150 C. A. R. C. A. R. DICTIONARY OF MECHANICAL SCIENCE. upon H exactly 50 lbs, for 50 × 8 – 400, the whole load. If the road slopes 4 inches in a foot, b Q must be 4 inches, or the angle b A. Q. should be equal to the inclination of the road; for then the point Q will rise to a m when ascending such a road, and will press with its greatest force on R the back of the horse. In a word, the centre of gravity Q is placed in a point equidistant from the two wheels, but before the line of trac- tion A H, and before the axletree—the horse will bear a certain weight on level ground, a greater when going up hill, and has more occasion for it, and less weight, when going down hill, and does not require to be pressed to the ground. When carts are not made in this manner, we may, in some measure, obtain the same result by judiciously loading them. In a cart loaded with homogeneous materials, as sand, lime, &c, let us suppose the centre of gravity is at O, we should, with another load of heterogeneous materials, or bodies of different weights, place the heaviest at the bottom and nearest the front, which would lower the point a, bring it further forward, and nearer its pro- per position Q, where part of the load suspended before the centre of gravity would still come nearer Q ; but then the poor horse is very injudiciously burdened. Description of different Carriages that move without Horses.— In the annexed figure is repre- sented a carriage invented by Mr. Richard, a phy- sician in Rochelle, which moves with- out horses, merely by the exertion of the passengers. The machinery by which this is ef- fected, is placed in a box behind the carriage, and is shewn in the 2d figure, where A. A is a small - axis fixed in the box, and B a pulley, over which a rope passes, whose two extremities are tied to the ends of the levers or the other ends of the levers are fixed by joints to the cross beam. The cranks FF are fixed to the axle KL, and move upon it as a centre. Each of them has a detent tooth at F, which catches in the teeth of the wheels H, H, so that they can move from F to H without moving the wheel, but the detent tooth catches in the teeth of the wheels when the cranks are brought backward, and therefore bring the wheel along with them. When the foot of the passenger, therefore, is placed upon the treddle D, it brings down the crank F and along with it the wheel H, so that the large wheels fixed on the same axis perform part of a revolution; but when D is depressed, the rope D A descends, the extremity C of the other treddle rises, and the crank F rising along with it, takes into the teeth of the wheel H., so that when the elevated treddle C is depressed, the wheels H, H, and consequently the wheels I, I, perform another part of a revolution. In this way, by con- tinuing to work at the treddles, the machine advances with a regular pace. A carriage of this kind, where the mechanism is much more º treddles C, D ; simplc and beautiful than that which we have described, has been lately invented and constructed by Mr. Nasmyth, of Edinburgh, a gentleman whose mechanical genius is scarcely inferior to his talents as a painter. The pulley B and axle AA, are rendered unnecessary; leather straps are substituted in place of the cranks F, F, and the whole mechanism is contained in two small cylindrical boxes, about six inches in diameter, and one and a half broad. A carriage driven by the action of the wind is exhibited in the annexed figure. It is fixed on four wheels, and moved by the impulse of the wind upon the sails C,D,be- ing guided by the rudder E. Carriages of this kind will answer very well in a level country where the roads are good and the wind fair; and are said to be used in China. In Holland they sometimes use similar vehicles º for travelling ºf upon the ice: - - sº but they have a sledge instead of wheels, so that if the ice should happen to break, there will be no danger of sinking. Stephinus, a Dutch- man, is said to have constructed one of these carriages with wheels, which travelled at the rate of 21 miles an hour with a very strong wind. - Dr. Phebus, of New York, has caused a wheel to be con- structed which is put in motion by the wind. The plan of it is very simple. It has eight horizontal spokes attached to a per- peºdicular axle. Every one of the spokes is furnished with a sail which extends or contracts at pleasure, something like the sails of a vessel. Every sail is hooked up, from the right to the left, to the first loop of that which follows; and they are sºficiently large to receive the full impulse given by the wind. This machine, which is more easy to conceive than to describe, *Very lºgenious, and may be employed in a great number of manufactures. The carriage represented in the annexed figure, is made so as tº sail against the wind by means of the spiral sails E, F, G, H, one of which, F, is expanded by the wind. The impulse of the wind upon the sails gives a rotatory motion to the axle M, furnished with a cog-wheel K, whose trundles act upon teeth placed on the inside of the two fore wheels. A carriage which cannot be overturned, is represented in the next figure, where A B is the body of the carriage, con- sisting of a hollow globe, made of leather or wood, at the bottom of which is placed an immoveable weight. Two hori- zontal circles of iron, D, E, connected with bars H, I, and two vertical circles F, G, surround the globe; and the wheels are C. A. R. DICTIONARY OF C. A. R. 151 MECHANICAL SCIENCE. fastened by a han- dle K to the per- pendicular bars H, I. O, P, are handles or shafts by which to move the machine along. N is one wheel, and tº on the opposite side is another. O is a window. The door may be next to O. P. Then, since the body of the carriage moves freely in every di- rection within the iron circles, the - - centre of gravity will always be near C, and the carriage will preserve an upright position even if the wheels and frame were overturned. stage Coaches and Waggons.—The danger of a stage coach overturning, arises either from two wheels on one side being driven into a hole, a ditch, or over a high bank, or running quickly to the side of a road very much rounded from its crown; or from turning a sharp corner with great velocity. The breaking down of any coach is a disastrous and fatal accident, which will happen in future, as it has happened here: tofore; and can only be prevented by the use of two pairs of idle wheels placed within the wheels in use, which is much the same as if we were travelling in two separate carriages. A coach may be overturned by the centre of gravity being placed too high. Holes, ditches, banks, rounded roads, cor- ners, and unequally loading to displace the centre of gravity, are all to be avoided by care, skill, and prudence; and In general by having the wheels perpendicular to the road, i.e. to the horizon, for the broader the base, and the nearer the line of direction is to the centre, the more firmly does the coach roll along; on the contrary, the narrower the base, i.e. the wheels, such as the conical, and the nearer the line of direction is to its side, the more easily may the coach be overthrown. suppose an overloaded waggon slopes on an uneven road, as shewn in the annexed figure, till the centre or gravity is at the point A : your eye will tell you that a vehicle thus situated, must overset; and the reason is, that the centre of gravity A, is not supported; for if you draw a perpendi- cular line from it to the ground at C, it does not fall under the waggon within the wheels, and is therefore not sup- ported by them. If, however, we re- move the centre of gravity to B, by taking off the upper part of the load, the waggon will not overturn, because the line of direction B D falls within the wheels at D. The wheels of carriages turn round, on account of the fric- tion they sustain in contact with the roads; and large wheels are more advantageous than small ones. In four-wheeled car- riages, the fore wheels are made smaller than the hind ones, for the conveniency of turning; otherwise they would be better of the same size. Broad wheels are better for heavy carriages— such as waggons—because they press and harden, instead of cutting up the roads, as small wheels do. Much attention has of late been paid to the safety of pas- sengers, by the construction of coaches in which the centre of gravity is brought very low, and the risk thereby greatly lessened. The legislature should pass an act to compel wag- gon-masters, van-proprietors, and coach-makers, to turn out such machines only as have their centres of gravity placed within the line of direction, when loaded at their utmost draught. It may be indifferent to draught, whether a ton be placed on the roof of a coach, or at its floor 2 feet from the ground; but it is material to danger and safety, that a ton weight be within 2, rather than 7 feet of the ground. CARTES, RENNes des, a celebrated French mathematician. Des Cartes explains mechanically how the world was formed. and how the present phenomena of nature came to arise. He supposes that God created matter of an indefinite extension, which he separated into small square portions or masses, full of angles: that he impressed two motions on this matter; the one, by which each part revolved about its own centre; and another, by which an assemblage, or system of them, turned round a common centre. From whence arose as many dif- ferent vortices, or eddies, as there were different masses of matter, thus moving about common centres. The consequence of these motions in each vortex, according to Des Cartes, is as follows:–The parts of matter could not thus move and revolve amongst one another, without having their angles gradually broken ; and this continual friction of parts and angles must produce three elements; the first of these, an infinitely fine dust, formed of the angles broken off; the second, the spheres remaining after all the angular parts are thus removed; and those particles not yet rendered smooth and spherical, but still retaining some of their angles and hamous parts, from the third element. Now the first or subtilest element, according to the laws of motion, must occupy the centre of each system, or vortex, by reason of the smallness of its parts: and this is the matter which constitutes the sun, and the fixed stars above, and the fire below. The second element, made up of spheres, forms the atmosphere, and all the matter between the earth and the fixed stars, in such sort, that the largest spheres are always next the circumference of the vortex, and the smallest next the centre. The third element, formed of the irregular particles, is the matter that composes the earth, and all terrestrial bodies, together with comets, spots in the sun, &c. He accounts for the gravity of terrestrial bodies from the centrifugal force of the ether revolving round the earth; and upon the same general principles he pretends to explain the phenomena of the magnet, and to account for all the other operations in nature. - Des Cartes infers the existence of God from the principle, * Cogito, ergo sum;” “I think, therefore I am!” and thinks his inference just, because it satisfies his reason: he proceeds on a supposition, that what satisfies his reason is true; and takes it for granted, that his reason is not a fallacious but a true faculty: hence his argument proceeds on a supposition, that the point to be proved is true. He therefore attempts to prove the truth of our faculties by an argument which evidently and necessarily supposes their truth; and consequently his meta- physics is built on sophisms. As this philosopher doubted where he ought to have been confident, so he is often confident where he ought to doubt. He admits not his own existence till he thinks he has proved it; yet his system is replete with hypotheses, taken for granted without proof, almost without examination. He sets out with the profession of universal scepticism, while many of his theories are founded on the most unphilosophical credulity. Des Cartes erred materially when he concluded, that the most perfect kind of science was to be arrived at by inferring effects from their causes; for, con- sistently with this conclusion, he endeavoured, from his know- ledge of the Deity, (which must necessarily be imperfect,) to deduce an explication of all his work, and thus produced a system almost in every respect repugnant to º expe- riment. Des Cartes was so far from applying geometry and observations to natural philosophy, that his whole system is one continued blunder, on account of his negligence in that point. His theory of vortices, upon which his system is founded, is absolutely false; for Newton has shewn, that the periodical times of all bodies that swim in vortices, must be directly as the squares of their distances from the centre of them; but it is evident, from observations, that the planets, in mov- ing round the sun, observe a law quite different from this; for the squares of their periodical times are always as the cubes of their distances; and therefore, since they do not observe that law, which of necessity they must if they swim in a vortex, it is a demonstration that there are no vortices in which the planets are carried round the sun; and therefore Des Cartes' hypothesis is absurd, irrational, and not capable of mathema- tical proof. T52 C A S C A S Diction ARY of MECHANICAL scIENCE. The Cartesian system has been often altered and mended; many ingenious men, for full a century, employing their talents in reforming one part and new-modelling another. But it is now acknowledged on all hands, that the foundation was faulty, and the superstructure erroneous; so that the fabric, though allowed to be a work of genius, is abandoned to neglect and ruin, and is pointed at as a memorial of philosophical presumption. Yet this system, or one much more absurd, has been broached of late, by a person who denominates his vaga- ries, “the philosophy of Atomic motion.” Des Cartes died in 1650. . • * - CARTWRIGHT, a person who makes carts, ploughs, har- rows, wheelbarrows, and in short all sorts of country and farm- ing carpentry, for the word wright signifies in the North, a joiner. But cartwrights are confounded with wheelwrights, though the latter only were recognized in old times as the legitimate makers of carriages, of what name soever these might be called. • - CASKS, The Manufacture of, is now much facilitated by machinery, which was invented by Messrs. Plakete and Brown, in 1811, and is thus perspicuously described in Dr. Gregory's “Mechanics.” - “First. The machinery for cutting the stave consists of a stout bench, having a board or platform annexed to it, capable of being moved endways, to which another board is connected, so arranged as to be moved across it steadily by racks and pinions, or screws. This last board has a hollow part made in it, in which the staveboard may be laid, so that one edge of it may project clear beyond the edge of the first mentioned board: a circular saw is placed either above or below the bench, having its axis at right angles to the line of motion of the first mentioned board, and opposed to the direction of the course of the projecting part of the staveboard: this circular saw is made flat, when the straight-edged staves are to be cut; and is dished, or of a spherical shape, when staves with curved edges are wanted. “The board first mentioned is moved either in a right line, or is made to assume a curved course by being confined in its motion by curved grooves, or by curved rods moving against pins; and by the proper management of these sliding boards, the staveboard is cut by the circular saw, of the shape desired. “The machinery next used consists of a large lathe, in which the cask is turned in a vertical position when it is of a large size, (after it is formed in the usual manner from the staves prepared as above described,) being either fixed in a great chuck placed beneath it, or in a cylindrical cage, which sur- rounds it, fixed upon a strong upright arbor, and revolving between collars, where it serves the office of a mandril. In this lathe the chime and groove for receiving the head are turned in the cask by the application of a proper tool. When the cask is small, the cage is made to turn in a horizontal position, instead of revolving vertically. “The third operation is to form the head, which is pinioned together as usual, after having the pinholes made by piercers, projecting from the mandril of a lathe; the distances and depth of which holes are correctly regulated by gauges ; it is then turned on a flat revolving table, from which points project to hold it fast, and against which it is held by another revolving piece, that is screwed towards the first, where it is brought to the proper size of the cask by fit tools. “The fourth operation is to turn the whole cask at the out- side; for which purpose, it is placed in a large lathe between two chucks, made to fit into the chines, and attached to the head by points ; and then the surface of the cask is turned smooth by a spokeshave, or other fit instrument, held against it by a rest properly placed for the purpose. “The patentees bend the wooden hoops for their casks in a more expeditious manner, by fastening one end of them to the circumference of a wheel, and pressing them against the wheel as it is turned round: they also describe a method of forming the projecting part in the bung staves of the small casks, called bottles, by flat or concave circular saws, which cut the face of the stave on each side close up to the projection; and lastly, in giving motion to this machinery, the inventors use any of the usual first movers, and millwork, as may be necessary.” metal, plaster of Paris, &c. CASSINI, JoHN DOMINIC, an eminent astronomer, born at a town in Piedmont, in 1625. In 1650 he was invited to the senate of Bologna to be their public mathematical professor, while he was yet but twenty-five years of age. He resolved an astronomical problem, which Kepler and Bullialdus had given up as insolvable, viz. to determine geometrically the apogee and eccentricity of a planet, from its true and mean place. In 1666 he printed at Rome a collection of astronomical pieces, and among others, a “Theory of Jupiter’s Satellites.” Cassini died in 1712, in the 87th year of his age. - CASSINI, John James, the son and successor of the above, born at Paris in 1677, and educated at the Mazarine College, under Varignon, Professor of Mathematics. At the age of seventeen he was admitted a member of the Academy of Sciences; and in 1696 he visited England, where he was chosen a Fellow of the Royal Society. He succeeded his father in 1712, and enriched the stock of science with many valuable discoveries. He died in consequence of a fall, in 1756. CASSIQPEIA, one of the Northern Constellations, repre- sented as the Wife of Cepheus, and Mother of Andromeda, but is called El Seder, the Cedar tree, by Ulug Beig.—The boundaries and contents are: north by Tarandus, east by Camelopardalis and Perseus, south by Andromeda, and west by Cepheus...This constellation, situated between 45° and 75° north declination, passes vertically over the British isles, and a large portion of Europe. It lies between 47° and 55° right ascension. It contains 55 stars, viz. five of the 3d magnitude, five of the 4th, &c. The head and body of this lady are placed in the Milky Way, her right foot resting on the Arctic Circle. Relatively to the two Bears, Cassiopeia is placed opposite to the space between them, and she is very easily distinguished by five stars of the 3d magnitude. In the year 1752, Tycho Brahe discovered in this constellation, a new star which shone with more light than Venus, till 1574, when it disappeared entirely. Schedir, a, having 7° 35' 7", or Oh 29' 40" right ascension, and 55° 32' 58? declination north, culminates or comes to the meridian at Lon- don, for the first day of every month during the year, as shewn in the following table : Meridian Altitude 85° 58' 2" north. MONTH. CU LM. MONTH. CULM. MONTH. CULM. ho. mi. - ho. mi. ho. mi. Jan. 5 43 A. May 9 51 M. Sept. 1 41 M. Feb. 3 31 A. June 7 41 M. Oct. 11 54 A. March 1 46 A. July 5 4 1 M. Nov. 10 1 A. April 11 41 M. Aug. 3 41 M. Dec. 7 56 A. CASTING and MoULDING. The art of taking impressions from pieces of sculpture, medals, &c. is of importance in the fine arts. To procure a cast from any figure, bust, medal, &c. it is necessary to obtain a mould, by pressing upon the thing to be copied some substance capable of being forced into all the cavities or hollows of the sculpture. When this mould is dry and hard, some substance which will fill all the cavities of the mould is poured into it: the form of the original from which the mould was taken, is now accurately represented. Mould- ing in any particular manner depends upon the form of the subject. When there are no projecting parts but such as form rectilineal angles with the principal surface of the body, nothing more is necessary than to cover it over with the sub- stance of which the mould is to be formed, and to take it off clean, and without bending. It may be laid horizontally, and will bear to be oiled without injury. The substances used for moulding are various, according to the nature and the situation of the sculpture, as wax, This last is prepared in a fine powder mixed with water, and poured over the mould to a convenient thickness, after oiling it, to prevent the plaster from sticking. A composition of bees’ wax, resin, and pitch, makes a very desirable mould, if many casts are to be taken. If the situa- tion of the sculpture be perpendicular, clay, or some similar substance, must be used. The best kind of clay is that with which sculptors make their models; it is worked to a due con- sistence, and having spread it out to a size sufficient to cover all the surface, it is sprinkled over with whiting, to prevent it from adhering to the original. Bees’ wax and dough, or the crumb of new bread, may also be used for moulding some small subjects, as impressions of seals and bijoux. When C. A S C A S DíCTIONARY OF MECHANICAL scIENCE. T53 there are undercuttings in the bas-relief, they must be first filled up before it can be moulded, otherwise the mould could not be got off. When the casts are taken afterwards, these places must be worked out with a proper tool. When the model, or original subject, is of a round form, or projects so much that it cannot be moulded in this manner, the mould must be divided into several parts; and it is frequently necessary to cast several parts separately, and afterwards to join them together. In this case, the plastër must be tempered with water to such a consistence, that it may be worked like soft paste, and laid on with some convenient instrument, compressing it till it adapt itself to all parts of the surface. When the model is thus covered to a convenient thickness, the whole is left at rest till the plaster become firm, so as to bear dividing without falling to pieces by any slight violence ; it must then be divided into pieces to be taken from the model. This is done by cut- ting it with a thin-bladed knife; being now divided, it must be cautiously taken off, and kept till dry ; but, before the separa- tion of the parts is made, they are notched across the joints, at proper distances, that they may with certainty be put together again. The art of properly dividing the moulds, to make them separate from the model, requires dexterity and skill. Where the subject is of a round or spheroidal form, it is best to divide the mould into three parts, which will then easily come off from the model; and the same will hold good of a cylinder, or any regular curve figure. ~ The mould being thus formed, and dry, and the parts put together, it must be first oiled, and placed in such a position that the hollow may lie upwards. It is then filled with plaster mixed with water; and when the cast is perfectly set and dry, it is taken out of the mould, and repaired where necessary. This finishes the operation. In larger masses, where there would otherwise be a great thickness of the plaster, a core may be put within the mould, as was observed in regard to the cast- ing of statues, to produce a hollow in the cast. This saves expense of plaster, and renders the cast lighter. In the same manner, figures, busts, &c. may be cast of lead, or any other metal, ih the moulds of plaster or clay; the moulds must be perfectly dry, for should there be any moisture, the sudden heat of the metal will convert it into vapour, and pro- duce by its expansion, an explosion, that would blow the melted metal about to the great danger of the artist. To take a Cast in Metal from any small Animal, Inseet, or Vegetable.—Prepare a box, sufficiently large to hold the animal, in which it must be suspended by a string : the legs, wings, &c. of the animal, or the tendrils, leaves, &c. of the vegetable, ºust. be separated and adjusted in their right position by a pair of pincers. A due quantity of plaster of Paris mixed with talc, must be tempered to a proper consistence with water, and the sides of the box oiled. Also a straight piece of stick must be put to the principal part of the body, and pieces of wire to the extremities of the other parts, that they may form, when drawn out after the matter of the mould is set and firm, proper chan- nels for pouring in the metal, and vents for the air, which otherwise, by the rarefaction it would undergo from the heat of the metals, would blow it out, or burst the mould. In a short time the plaster will set, and become hard; the stick and wires may now be drawn out, and the frame in which the mould was cast taken away; and the mould must then be put, first, into a moderate heat, and, afterwards, when it is as dry as it can be rendered by that degree, removed into a greater, which may be gradually increased, till the whole be red hot. The animal or vegetable enclosed in the mould will then be burnt to a coal; and may be totally calcined to ashes, by blowing for some time into the charcoal and passages made for pouring in the metal, and giving vent to the air. This operation, at the same time that it destroys the remainder of the animal or vegetable matter, will blow out the ashes. The mould is then allowed to cool gently; the destruction of the substance that had been included in it, has now produced a corresponding hollow ; but it may nevertheless be proper to shake the mould, and blow with bellows into each of the air vents, to free it wholly from any remaining ashes; where there may be an opportunity of filling the hollow with quicksilver, it will be found an effectual ethod of cleaning the cavity, as all dust and ashes must rise to the surface of the quicksilver, and be poured out with it. 17. ** The mould being thus prepared, must be heated very hot, when used, if the cast is to be made of copper or brass, but a less degree will serve for lead or tins. The metal being poured into the mould, it must be gently struck, and then suffered to rest till it be cold; it is then carefully taken from the cast, but without force; such parts of the matter as appear to adhere more strongly, are to be softened, by soaking in water till they be entirely loosened, that none of the more delicate parts of the cast may be broken off or bent. When talc cannot be obtained, plaster alone may be used; it is apt however to be calcined, by the heat used in turning the animal or vegetable from whence the cast is taken, and to become of too incoherent and fusible a texture. Stourbridge clay, washed perfectly fine, and mixed with an equal part of fine sand, may be employed. Pounded pumice-stone, and plaster of Paris, in equal quantities, mixed with washed clay in the same proportion, make exellent moulds. To take a Cast in Plaster from a Person's Face.—The person whose likeness is required in plaster, lays down on his back, the hair is tied back, so that none of it may cover the face. Into each nostril a conical piece of stiff paper open at both ends is conveyed, to allow of breathing. The face is then lightly oiled over with salad-oil, to prevent the plaster from sticking to the skin. Fresh burnt plaster is mixed with water to a proper consistence, and poured in spoonfuls all over the face, (tak- ing care the eyes are shut,) till it is entirely covered to the thickness of a quarter of an inch. This substance will grow sensibly hot, but this the patient must not fear ; for in a few minutes the plaster will be hard. . This being taken off, will form a mould, in which a head of clay may be moulded, and therein the eyes may be opened, and such other additions and corrections may be made as are necessary. Then, this second face being anointed in oil, a second mould of plaster is made upon it, consisting of two parts joined lengthwise along the ridge of the nose; and in this a cast in plaster is taken, as an exact likeness of the original. To take Casts from Medals.--To take copies of medals, a mould must first be made, of plaster of Paris, or of melted sulphur. After having oiled the surface of the medal with a little cotton, or a camel's hair pencil dipped in oil of olives, a hoop of paper must be put round the medal, standing up above the surface, of the thickness you wish the mould to be... Take now some plaster of Paris, mix it with water to the consistence of croam, and with a brush rub it over the surface of the medal, to prevent airholes from appearing ; then immediately after- wards make it to a sufficient thickness, by pouring on more plaster. Let it stand half an hour, when it will have grown so hard, that you may safely take it off; then pare it smooth on the back, and round the edges neatly. In cold or damp wea- ther it should be dried before a brisk fire. When the mould is large, if you cover its face with fine plaster, a coarser sort will. do for the back: but no more plaster should be mixed up at one time than can be used, as it will soon get hard, and cannot be softened without being burned over again. Sulphur must not be poured upon silver medals, as this will tarnish them. To prepare your mould for casting sulphur, put plaster of Paris into it, take half a pint of boiled linseed oil, and one ounce of oil of turpentine, and mix them together in a bottle; dip the surface of the mould into this mixture; take the mould out again, and when it has sucked in the oil, dip it again. Repeat this tik, the oil begins to stagnate upon it; then take a little cotton wool, hard rolled up, to prevent the oil from stick- ing to it, and wipe it carefully off. Lay it in a dry place for a day or two, (if longer the better,) and the mould will acquire a very hard surface from the effect of the oil. To cast plaster of Paris in this mould, proceed with it in the same manner as above directed for obtaining the mould itself, first oiling the mould with olive oil. When casts are wanted of sulphur, the material must be melted in an iron ladle. - To take Casts with Isinglass.-Dissolve isinglass in water over the fire. With a hair brush lay the wetted isinglass over the medal. Cover it properly, and let it dry. When hard, raise the isinglass with the point of a knife, and it will fly off like horn, leaving a sharp impression of the medal. You may make the isinglass of any colour, by mixing that colour with it when in a state of solution; or you may breathe on the concave 2 R 154 C. A. T. C. A 't DICTIONARY OF MECHANICAL SCIENCE. side, and lay gold leaf on it, which, by shining through, will make it appear like a gold medal. A little carmine mixed with the isinglass will give it the appearance of a copper medal, observing to lay the gold on the concave side. To cast Small Works in Sand.-The sand is usually a soft yellowish clammy substance; but as we sce it in an iron foun- dery, it is black, from the charcoal which the workmen strew over it. This sand, after being placed over a trough to receive it, is worked on a board, with a roller and a knife. The work- men then take a board, putting a ledge round, and fill it with sand, a little moistened, to make it cohere. Then the wood or metal models of what is intended to be cast, are applied to the mould, and pressed into the sand, to leave the impression. Along the middle of the mould, half of a small brass cylinder is laid; the metal runs through this chasm into the models; from this are placed several others, to each model placed in the frame. After the frame is finished, the workmen then take out the patterns, by loosening them all round, that the sand may not give way. They then work the other half of the mould with the same patterns, in another frame. In this last frame are pins, which, entering into correspondent holes in the other, make the The He extends the two cavities of the pattern fall exactly on each other. frame thus moulded, is carried to the melter. chief canal of the counterpart, adds the cross canals to the several models in both, and strewing mill-dust over them, dries them in an oven. Both parts of the mould being dry, are joined by the pins, and screwed up like a press. While the moulds are preparing, the metal is fusing in a crucible of a size proportionate to the quantity of metal intended to be cast. To cast Cannon.—The casting cannons, mortars, and other pieces of ordnance, is like that of statues and bells, especially as it regards the mould, wax, shell, furnaces, &c. The metal is different, however, having a mixture of tin, which is not in that of statues; and only half the quantity of tin that is in bells, at the rate often pounds weight of tin to a hundred of copper. Cannons are always thickest at the breach, where the greatest effort of the gunpowder is made, and diminishing thence to the muzzle; so that if the mouth be two inches thick of metal, the breech is six. Its length is measured in calibers, or diameters of the muzzle. Six inches at the muzzle require twenty calibers, or ten feet in length; there is about one-sixth of an inch allowed for the deviation of the ball, and in this manner are all our guns estimated. CASTLE, a Fortress, or building rendered defensible either by nature or art. In the following engraving, A is the barbi- can ; B the ditch, or moat; C the wall of the outer ballium ; º ºf F # - * º º s C cºs N ſ |X. º or the outer ballium; E the artificial mount; F the wall of the inner ballium; G the keep, or dungeon. All the towers, maga- zines, &c. speak for themselves. Between the outer ballium and the barbican, and directly over the moat or ditch, the drawbridge is constructed, opening or rising to the ballium gate, and leaving the way impassable to those who may try to force and enter the barbican. CASTOR and POLLUX, the allegorical figures in the sign Gemini, which give name to the two principal stars in that constellation. - CAT, in sea affairs, a ship of 600 tons or thereabouts, carry- ing from 20 to 30 keels (or barges) of coals. CAT is also a tackle, or combination of pulleys, to suspend the anchor at the cat's-head. CATACOMB, a Grotto, or subterraneous place for the burial of the dead, as the sepulchre of the martyrs in the Appian Way, about three miles from Rome; the catacombs of Naples, Syracuse, Catanea, Malta, Paris; but above all, those, in Egypt are the most celebrated. CATALOGUE, a list or enumeration of books, or of the stars, or of the Popes, as the Jesuit's Propilaum. CATAPULTA, in Antiquity, a military engine for throwing stones or darts upon an enemy; but modern warfare dispenses with those awkward machines, and so shall we, CATARIRH, in Medicine, a distillation or defluxion from t head upon the mouth and aspera asteria, and through them upon the lungs CATENARY, CATENAR1A, in the higher Geometry, a mecha nical curve, which a chain or rope forms itself into by its own weight, when hung freely between two points of suspension, whether those points be in the same horizontal plane or not. See Chain Bridge. CATGUT, fiddle strings, made of the dried and twisted guts of sheep, lambs, dogs, and cats. The Lyonois and Italians are the great manufacturers of catgut for our musicians, watch- makers, cutlers, turners, and other artificers. CAT-HEADS, two strong short beams of timber, projecting almost horizontally over the ship's bows on each side of the bowsprit. That part of the cat-head which rests upon the fore- castle is securely bolted to the beams; the other projecting part carries in its extremity two or three small wheels, or sheayes of brass or strong wood, about which a rope called the cat-dole passes, and communicates with the cat-block, which also contains three sheaves. The cat-head also serves to sus- pend the anchor clear of the bow, when it is necessary to let it go : it is supported by a sort of knee, which is generally ornamented with sculpture. CATOPTRICS, the science of reflex vision, which is treated of under the article Mirror. CATSALT, formed out of the bittern, or leach brine, that runs from the salt when taken from the pans at the salt works, is very beautifully granulated, sharp and pungent, and much more pleasant at the table than the fine but white powdered salt in common use. Fashion, not taste, must have consigned the large beautiful crystals of catsalt to the makers of hard soap and fish curers. C E M C E M DICTIONARY OF MECHANICAL science. 155 . CU rWe. ... CAT’S-EYE, or SUN Stone, a gem whose colours vary like the opal, very hard, semitransparent; and which, from the several points it may have naturally, or into which lapidaries can fashion it, reflects the light with a kind of yellowish radia- tion, something similar to the eyes of a cat, whence the name of this Siberian onyx. CAUSTIC, or CATAcAustic CURves, in the higher Geometry and Optics, are the species of curves formed by reflection, or by joining the points of concurrence of several reflected rays. The caustic of the circle is a cycloid, or epicycloid, formed by the revolution of a circle upon a circle. The catacaustic of the common cyloid, when the rays are parallel to its axis, is also a common cycloid, described by the revolution of a circle upon the same base. That of a logarithmic spiral is also the same If the inside of a smooth bason, containing in it any white liquor, as milk, be placed in the sun's rays, or in a strong candlelight, it will exhibit a very perfect catacaustic curve. , CAWKING or CAULKING a ship, is driving a quantity of oakum, or untwisted rope, into the seams of the bottoms and decks of ships, in order to prevent the entrance of water; and caulking irons are chisels for that purpose, being some broad, some round, and some grooved. CELA SCULPTORIS, or PRAxiteles, the Engraver's Tools, is a small modern constellation, bounded on the north by Lepus, east by Columbia, south by Equuleus Pictorius; and west by Horologium and Eridanus. There are sixteen stars assigned to this asterism, in the Britannic Catalogue. CELESTIAL, relating to the heavens; hence we say Celes- tial Globe, Celestial Atlas, &c. CELLAR CRANE, a machine represented in the following figure, and is very useful to wine-merchants, brewers, &c. in drawing up and letting down casks full of wine, beer, &c. It saves the trouble and inconvenience of horses, and in many places can be used where horses could not. A, A are two wooden props, about 6 feet in height, and jointed together like a ruler at B. They are connected to each other by an iron round bar C, and wooden bar at the bottom, D. The iron prongs E E fasten the uprights steadily to the edge of the cellar; F is the axis round which two ropes are coiled, the ends of which are fastened to the two clamps G, G. On the axis F is fixed the iron wheel H of 3 feet in diameter: in the teeth of this works *_2 LZ Z Tºrº. zºº. - Tº G D Gr the pinion I, of about 6 or 7 inches in diameter, and is turned by the handle at K. It is evident, by the figure, that when the two ropes are slipt over the ends upon the barrel, either at the top or bottom of the cellar, by turning of the winch K towards or from the operator, the barrel can be safely and expeditiously taken out or lowered down. When the crane is done with, it shuts up, by unscrewing the nut B, taking the wheel and axis away out of the loops at L, and folding the sides at A together, like a jointed rule ; it may then be taken away in the cart or dray, or taken in the men’s hands. • CEMENT, in general, is any glutinous substance capable of uniting and keeping things together in close cohesion. Ce- ments are of various compositions, according to the substances to which they are applied, and their exposure to heat and moisture. (ºr Common Glue.—Common glue is formed by extracting the gelatinous part of cuttings or scraps of coarse leather, or the hides of beasts: it is never manufactured but in a large way. . Isinglass Glue.—Isinglass glue is made by dissolving beaten isinglass in water by boiling; having strained it through a coarse linen cloth, it evaporates again to such a consistence, the consistence of glue. part of the surface. - that, being cold, the glue will be hard and dry. This cement is improved by dissolving the isinglass in proof spirit by heat, or by adding to it, when dissolved in water, an equal quantity of spirits of wine. It is still further improved, by adding to the isinglass, previous to its solution in spirits, one-third of its weight of gum ammoniac. Expose the mixture to a boiling heat until the isinglass and gum are dissolved, and until a drop of the composition becomes instantly stiff as it cools. It will in future melt with a degree of heat little exceeding that of the human body, and, in consequence of becoming stiff in cooling, forms a valuable cement for fixing on the antemmae, &c. of insects in the cabinet of natural history. The easy melting of this cement is no objection to its use, for it owes this property' only to the presence of the spirit, which evaporates soon after it has been applied. When used to join broken glass or china, the pieces should be previously warmed, and immersion in hot water will give them a sufficient degree of heat. Wipe off the water before applying the cement, which may be laid on with a pencil ; then press the pieces together, binding them with a string or a bit of soft wire, if necessary. For nice purposes, this isinglass glue is preferable to common glue, being stronger, and less liable to soften by heat or moisture. Parchment Glue is made of one pound of shreds of parch- ment or vellum, boiled in six quarts of water, till the quantity be reduced to one quart; the fluid is strained off from the dregs, and then boiled again till it be of the consistence of glue. Glovers' cuttings of leather dressed with alum, instead of being tanned, makes a colourless glue. * To make Signboard Glue.—Melt common glue with water to a proper consistence; add one-eighth of boiled linseed oil, drop- ping it gently into the glue, which is to be kept stirring all the time. A strong glue is made by adding some powdered chalk to common glue, and another that will resist water by adding half a pound of common glue to two quarts of skimmed milk. . To prepare Lip. Glue for Cementing Paper, &c.—Take of isinglass and parchment glue, each one ounce; of sugarcandy, and gum tragacanth, each two drachms; add to them an ounce of water, boil the whole, till the mixture appears, when cold, of Then form it into small rolls for use. This glue wetted with the tongue, and rubbed on the edges of the paper, silk, &c. to be cemented, will, on their being laid together, and suffered to dry, unite them as firmly as any other Lapland Glue-Laplanders' bows are composed of two pieces of wood glued together; one of them of birch, which is flexible, and the other of fir of the marshes, which is stiff, in order that the bow when bent may not break, and that when unbent it may not bend. When these two pieces of wood are bent, all the points of contact endeavour to disunite themselves, and to prevent that, the Laplanders employ the following cement:-They take the skins of large perches, and having dried them, moisten them in cold water until they are so soft that they may be freed from the scales, which are thrown away; probably eel skins would answer the same purpose. They then put four or five of these skins into a reindeer's bladder, or they wrap them up in a soft bark of the birch tree, in such a man- ner that water cannot touch them, and place them thus covered into a pot of boiling water, with a stone above them to keep them at the bottom. When they have boiled about an hour, they take them from the bladder or bark, and they are then found to be soft and viscous. In this state they employ them for glueing together the two pieces of wood which compose their bows, and which they strongly compress and tie up till the glue is well dried. These pieces never after separate. Cheese Glue.—Take skimmed milk cheese, freed from the rind, cut it into slices, boil it in water, stirring it with a spoon until it be reduced to a strong glue, which does not incorporate with water; then throw away the hot water; pour cold water over the glue, and knead it afterwärds in warm water, subject- ing it to the same process several times. Put the warm glue on a grinding stone, and knead it with quicklime until you have a good glue. To use this glue you must warm it; em- ployed cold, it is not so strong, but it may be used in that manner. This glue is insoluble in water as soon as it is dry, and it becomes so in forty-eight hours after it has been applied. 156 C E M C E M Diction ARY of MECHANICAL science. It may be used for glueing wood, cementing marble, and broken earthenware. Baits for catching fish may also be made of it. Fish are very fond of it, and it resists water. Jewellers' Cement.—In setting precious stones, pieces are sometimes broken off by accident, but these may be joined so correctly, that an inexperienced eye would not discover the stone to have been broken. Jewellers employ for this purpose a small piece of gum mastich applied between the fragments, which are previously heated sufficiently to enable them to melt the interposed gum. They are then pressed together, to force out the redundant gum. Turkey Cement for joining Metals, Glass, &c.—Dissolve six bits of mastich, as large as peas, in as much spirits of wine as will suffice to liquefy ; in another vessel dissolve as much isinglass (which has been previously soaked in water till it has swollen and is soft) in brandy or rum, as will make two ounces by measure of strong glue, and add two small bits of gum galbanum, or ammoniacum, which must be rubbed till they are dissolved; then mix the whole with a sufficient heat; keep it in a phial stopped, and when used set it in hot water. Broken China Cement.—Take quicklime and white of eggs, or old thick varnish; grind and temper them well, and it will be ready for use. Drying oil and white lead are used for cement- ing china and earthenware; but this cement requires a long time to dry. Where the vessels are not to endure heat or moisture, isinglass glue, with a little tripoli or chalk, is better; the juice of garlic also forms a strong cement, and the joining cannot easily be perceived. Chemical-Glasses' Cement.—In the whites of eggs mix equal quantities of wheat flour, fine powdered Venice glass, pulverized chalf, with half the quantity of fine brick dust, and a little scraped lint. This mixture is spread upon a linen cloth, and applied to the crack of the glasses; it should be dried before they are put to the fire. Turner’s Cement.—Melt together resin one pound, pitch four ounces; and, while boiling hot, add brick dust, until, by drop- ping a little upon a stone, you perceive it hard enough ; then pour it into water, and immediately make it up in rolls, and it is fit for use. Another, finer. Take resin one ounce, pitch two ounces; add red ochre, finely powdered, until you perceive it strong enough. Sometimes a small quantity of tallow is used, accord- ing to the heat of the weather, more being necessary in winter than summer. Either of these cements is of excellent use for turnerS. warm before the fire, you may fasten any thin piece of wood, which will hold fast while you turn it; when you want it off again, strike it on the top with your tool, and it will drop off immediately. Electrical Cement.—Melt in a pot, over a slow fire, one pound of resin; add as much plaster of Paris, in fine powder, as will make it hard enough, which you may know by trial; then add a spoonful of linseed oil, stirring it all the while, and try if it be hard and tough enough for your purpose; if it is not sufficiently hard, add more plaster of Paris; and if not tough enough, a little more linseed oil. This is for fixing the necks of globes or cylinders, or any thing that requires to be strongly cemented, for it is not easily melted when cold. . Another, softer. Take resin one pound, bees' wax one ounce; add as much red ochre as will make it sufficiently stiff; pour it into water, and make it into rolls for use. This cement is for cementing hoops on glasses, or any other mounting of electrical apparatus. Glass Grinders' Cement.—Boil pitch, adding thereto fine sifted wood ashés, until you have it of a proper temper, stir- ring it all the while; a little tallow may be added, as you find necessary. - . - Another, for small work. To four ounces of resin add one- fourth of an ounce of bees' wax, melt them together, adding four ounces of whitening made previously red hot. The whitening should be put while hot, that it may not have time to imbibe moisture from the atmosphere. Shell lac is a strong cement for metals, glass, or precious stones, while cutting, twining, or grinding them. The metal, &c. should be warm to melt it. Shell lac is excellent for fastening ruby cylinders in watches, and similar delicate purposes. By applying it to the side of a chuck, and making it l I}roken Glass Solder.—Broken glass is soldered by inter- posing between the parts, glass ground up like a pigment, but of easier fusion than the pieces to be joined, and then exposing them to such a heat as will fuse the cementing ingredient, and make the pieces agglutinate without being themselves fused. A glass for cementing broken pieces of flint glass may be made by fusing some of the same kind of glass previously reduced to powder, with a little lead and borax, or with borax only. . , Derbyshire Spar Cement, &c.—This cement is made with about eight parts of resin and one of bees' wax, melted together with a small quantity of plaster of Paris. If the cement is to fill up the place of any small chips that may have been lost, the quantity of plaster may be increased a little. When the ingre- dients are well mixed, and the whole nearly cold, the mass must be well kneaded together. The pieces of spar to be joined, must be heated until they melt the cement, and then pressed together, some of the cement being previously inter- posed. Melted sulphur applied to fragments of stones pre- viously heated (by placing them before a fire) to at least the melting point of sulphur, and then joined with the sulphur between, makes a pretty firm and durable joining. Little defi- ciencies in the stone, as chips out of corners, &c. may also be filled up with melted sulphur, in which some of the powder of the stone has been melted. Steam Cement.—To join the flanches of iron cylinders, and other parts of hydraulic and steam engines, the following methods are adopted by machinists:—Boiled linseed oil, litharge, red and white lead mixed together to a proper con- sistence, applied on each side of a piece of flannel, previously shaped to fit the joint, and then interposed between the pieces before they are brought home, (as the workmen term it) to their place by the screws or other fastenings employed, make a close. and durable joint. The quantities of the ingredients may be varied without inconvenicnce, taking care not to make the mass too thin with oil. It is difficult in many cases instantly to make a good fitting of large pieces of iron work. This renders it necessary sometimes to join and separate the pieces repeatedly before a proper adjustment is obtained. When this is expected, the white lead ought to predominate in the mix- ture, as it dries much slower than the red. A workman know- ing this fact, can be at little loss in exercising his own discre- tion in regulating the quantities. It is safest to err on the side of the white lead, as the durability of the cement is not thereby effected, a longer time only is required for it to dry and harden. When the fittings will not easily admit of so thick a substance as flannel being interposed, linen may be substituted, or even paper or thin pasteboard. This cement answers well also for joining broken stones, however large. Cisterns built of square stones, put together with this cement, will never leak, or want any repairs. In this case, the stones need not be entirely bedded in it; an inch, or even less, of the edges that are to be next the water, need only be so treated ; the rest of the joint may be filled with good lime. - Another of the same. This cement, preferable even to the former, for steam-engines, is prepared thus:—Take two ounces of sal ammoniac, one ounce of flowers of sulphur, and sixteen Qunces of cast iron filings or borings; mix them in a mortar, and keep the powder dry. When the cement is wanted for use, take one part of the above powder, and twenty parts of clean iron borings or filings, and blend them intimately by grinding them in a mortar. Wet the compound with water, and when brought to a convenient consistence, apply it to the joints with a wooden or blunt iron spatula. This is the cement with which the joinings of the Southwark cast-iron bridge were filled up and clasped. Action and reaction take place among the ingredients, and between them and the iron surfaces, which at last causes the whole to unite as one mass. After a time, the surfaces and the mixture become one. Roman Cement.—By a recent analysis of Parker’s Roman cement, by Monsieur Berthier, he finds that its constituents differ so little from the constituents of chalk and common clay, that he proposes the manufacturing of a similar cement by the mere mixture of them in certain proportions—One part of clay, and two and a half parts of chalk, sets almost instantly, and may therefore be regarded as Roman cement. , C E N C E N 157 DICTIONARY OF MECHANICAL SCIENCE Blood Cements, are used by coppersmiths to lay over the rivets and edges of the sheets of copper in boilers of the first class: they also give additional security to the joinings, and secure cocks from leaking. This cement is made by mixing pounded quicklime with oxen's blood: but unless used when fresh made, it will become hard. It is durable, cheap, and extensively applicable in the rougher branches of art. Flowr Paste Cement.—Flour paste for cementing, is formed principally of wheaten flour, boiled in water till it be of a glu- tinous or viscid consistence. It may be prepared of these ingredients simply for common purposes, but when it is used by bookbinders, or for paper hanging, it is usual to mix with the flour a fifth or sixth of its weight of powdered alum; and where it is wanted still more tenacious, gum arabic, or any kind of size, may be added. Rice Glue.--This elegant cement is made by mixing rice flour intimately with cold water, and then gently boiling it. It is beautifully white, and dries almost transparent. Papers pasted together with this cement will sooner separate in their own substance than at the joining, it is therefore extremely useful in the preparation of curious paper articles, as tea trays, ladies’ dressing and work boxes, and other articles which require layers of paper to be cemented together. In every respect it is preferable to common paste made with wheat flour. It answers well for pasting into books the copies of writing taken off by copying machines on unsized silver paper. With this compo- sition, made with a small quantity of water, that it may have a consistence similar to plastic clay, models, busts, statues, basso relievos, and the like, may be formed. When dry, the articles made of it are susceptible of a high polish ; they are also very durable. The Japanese make quadrille fish of this substance, which so nearly resemble those made of mother of pearl, that the officers of our East Indiamen are often imposed UlDOIl. - º; Sizes.-Common size, manufactured in the same manner, and generally by the same people as glue, is glue left in a maoister state, by discontinuing the evaporation before it is brought to a due consistence.’ - Isinglass Size, is prepared much in the same way as glue ; the quantity of water for dissolving it is increased; and the same makes good parchment size. - CENOTAPH, an empty tomb erected in honour of a deceased person, and is thus distinguished from the sepulchre in which a coffin is deposited. CENTAURUS, the Bull Pricker, as his name denotes, ranks among the old constellations. The Centaur is said to derive its name from those sons of Ixion and Nubes, whom fable represented half men, half horses; and the notions which the Americans entertained of the Spanish cavaliers, have been suggested, to persuade us that the ancients who first saw a man on horseback, conceived him and the animal to be one. The fable of the Centaurs and the Lapitha, is well known to every schoolboy. *The boundaries and contents of this constellation are: on the north by Hydra, east by Lupus, south by Crux, and west by Robur Caroli. There are thirty-five stars in this constellation, viz. two of the 1st magnitude, one of the 2d, six of the 3d, nine of the 4th, &c. The brilliants of this constella- tion are situated on the fect of the Horse; and with the adjoin- ing asterism of the Cross, make a very splendid shew in southern latitudes ; but the people of Britain are too far north to enjoy this sight. The star 3, in the western foot, culminates about 7 minutes before a, or at xix ho. 1'45", on the 1st of January, and by making an allowance of about 4 minutes for each succeeding day of the month, it will be on the meridian, January 2, at xvii.1 ho. 57' 21", on the 3d at xviii h. 52' 58", on the 4th at xv.111 ho. 48' 38", &c. - CENTESM, the 100th part of a thing. CENTRAL, something relating to a centre. Thus, we have CeNTRAI, Eclipse, Central Force, &c. Contral Eclipse is, when the centres of the luminaries exactly coincide, and are directly in a line with the eye of the observer. Central Forces are those forces which tend directly to or from a certain point or centre ; or they are forces which cause a moving body to tend towards, or recede from, the centre of motion; and are hence divided into two kinds, according to their different rela- tions to the centre, viz. whether it be to approach or to recede 18. from it; being called, in the former case, centripetal force, and in the latter, centrifugal. See Force. CENTRE, in a general sense, denotes a point equally remote from the extremes of a line, surface, or solid. The word signifies a point. CENTRE of an ARch. Under the word Bridge, the various forms of arches were noticed. We will now shew how the archstones are supported till the arch is completed; and the most commodious and least expensive manner in which this can be accomplished. 1. When the span is small, as cellars and vaults, the founda- tion of the side wall is dug out, the earth rounded over upon it, the arch thrown, and the earth afterwards dug away. 2. When it is necessary to use wood for the frame or centre, we must first consider, the weight to be supported ; secondly, the quantity of materials to be used, that shall be of sufficient strength to support such a weight; and, thirdly, the most effective method to apply these materials. First, the Weight to be supported.—A semicircular arch can be raised 30 degrees, (see Bridge,) without a centre. There are 120 degrees to support; and if the diameter be 20 feet, 120° will measure 20-943.93 + feet; say 21 feet. The key- stone of such an arch would be driven at 18 inches depth. The specific gravity of a cubic foot of hard stone, is 2:532. A stone 18 inches square, by 21 feet, gives 47.25 solid feet: the weight by the above specific gravity is 7477-307 lbs, or 66.753 cwt. being the weight that one rib of the centre frame must sustain. * - - - - - * In the span of 50 feet, the arch of 120° measures 52-36 feet; the archstone is 24 feet deep by 2 feet, is 5 superficial feet, which + 52-36 – 261-8 solid feet and 369-908 cwt. of specific gravity. Here the weight is increased upon the centre frame in the proportion of 66.5 to 309.9; or more than five times, for the difference of the centre framework. In the span of 100 feet, arch 104,719 feet, keystone 4 × 3, we have 1256-628 solid feet, 1775,848 cwt. specific gravity; above five times the weight of an arch of 50 feet span. In the span of 130 feet, the arch 156:13556 feet, the arch 5 × 3, as in the bridge of Dee at Aberdeen, we have 2042.0336 solid feet, and 2885’2838 cwt. the rib or beam of the frame centre. See STRENGTH OF MATERIALs. Secondly, the strength of timber requisite to support any of the foregoing weights may be ascertained thus:—In all mecha- nical structures, each member should not only be able to resist the strain under which it is constantly subjected, but should also be able to withstand those occasional shocks to which it is ever exposed. This is peculiarly the case in the framing of centre work for bridges. Every piece of wood employed is of a prismatic or columnar form, and is exposed either to longi- tudinal or transverse strain; and may be so used as to sustain a longitudinal tension, in withstanding a longitudinal com- pression, in resisting a transverse pressure, and in opposing the act of twisting or wrenching. But the investigation of these topics would interest few readers, and to those few the results would not be of much practical value. A batten or prism of wood, 5 inches square, and 14 feet long, supports a weight of 5300 lbs. which may be called its break- ing weight; and it has more than double the strength of a prism of 28 feet long, 5 inches square, for 1775 lbs. would break the latter. Every beam of wood becomes more liable to break by its length; 12 inches, 5 inches square, weight 104 lbs. more or less; and 10.4 lbs, at 13 feet distance, acts with a power of 135°2 lbs. This is the last term, and 0, the point of fracture, is the first term. The first and last multiplied by half the mum- ber of terms – the sum of all the terms ; or 135°2 × 6% = 878.8 lbs. added to 1775 = 2653-8, being very near the half of the force that breaks the prism of 14 feet. The weight that breaks a prism of 9 feet long and 5 inches square, is 8308. To reduce this experiment to one of greater dimensions, suppose one foot; similar solids of the same altitude are to one another as their bases; i.e. 25, the base of the 5 inch square is to 144, the base of 1 foot square, as the weight that would break the batten of 9 feet, to the weight that would break the batten of the same length and 12 inches square ; that is, the base 25 : 8308 : : 144 : 47854 Ibs. = 213-8125 tons; and the proportion, as above, for greater or less length of logs or spars. And a 2 S . 158 C E N C E N DICTIONARY OF MECHANICAL SCIENCE. I batten of any depth, and one half breadth, is equally strong in that position as if it had been square timber: hence the advan- tage in point of economy; for if the piece is set upon edge, suppose 9 inches deep and one broad, provided it receives no lateral tension, it will bear as much strain as if 9 inches square. In general, a beam the same length and breadth as another, but twice the depth, is four times stronger; and a beam of the same depth and breadth, and double the length, is only half so strong. These experiments were made upon well-seasoned oak; but between one-third and one-half of the absolute strength of these results will do in practice. We are now, in the third place, to consider the most effective method of applying these materials. . The late Mr. Rennie found, that cubes of one inch are crushed by the weights annexed: – Elm, . © tº e º 'o © e º e e º e s tº e a e © tº e º 'º e s sº a C & © tº e a e e s a 1°284 lbs. White deal, . . . . . . . . . . . . . . . . . . . . . . . . . 1:928 English oak, . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3°860 Craigleith freestone, . . . . . . © e. e. e. e. e. e. e. e. e. e. . . . . . 8°688 Cubes of 1% inch are, however, crushed with less loads in proportion; thus, Red brick, . . . . . . • & e º e = * . . . . . . . . . . . . . . . . . . 1817 lbs. Yellow baked brick,... . . . . . . . . . . . . . . . . . . . 2'254 Fire brick, . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3°864 Craigleith stone, . . . . . . . . . . . . . . . . . . . . . . . . . 15'560 White statuary marble, . . . . . . . . . . . . . . . . . . 13-632 Purbeck limestone, .... . . . . . . . . . . . . . . . . . . . 20-610 Cornish granite, of which Waterloo Bridge } 14°302 was built, . . . . . . . . . . . . . . . . . . . . . . . . . . Peterhead granite, . . . . . . . . . . . . . . . . . . . . . . . 18.636 Aberdeen blue granite, . . . . . . . . ... . . . . . . . . . 24°536 A pillar in the church of All Saints, at Angers, is 24 feet high and 11 inches square, supporting 60,000 lbs. which is not one- seventh of the weight that would crush it. Hence the delicacy of many pillars in Gothic buildings, and of those in the Exchange, Cornhill, London. Instead of a pier of 10 feet in a bridge of 50-feet span, one of 2 feet thick would be sufficient. How superfluous then are those enormous piers that obstruct the course of rivers. But the inquiry is with wood; and to arrive at our conclu- sion, let us consider precisely the strength of an arch above a right line parallel to the horizon. An arch recedes from a per- pendicular to a horizontal line, the force therefore that it will sustain, is, between the force that a body will carry in the per- pendicular, and that which produces a fracture upon any material in the horizontal direction. If the perpendicular is greater than the horizontal line, it will have more of the strength of the bruising force, than of the transverse fracture. This force is explained by the ratio compounded of the bruis- ing force and that of the transverse fracture, i.e. the absolute and relative force. In other words, if a geometrical mean be taken between the elevation of the arch, as pressure of abso- lute strength, and the length of the horizontal line, this mean will be the strength of the arch above the horizontal line. Experiments made upon prisms of seasoned oak, 2 inches square, and 2, 4, or 6 feet high, shewed them crushed by the vertical pressures of 17,500 lbs. 10,500 lbs. and 7000 lbs. ; but if 4 inches square, and of the same altitudes, they would give way under loads of only 80,000 lbs. 70,000 lbs. and 50,000 lbs. In the first set of trials, the mean cohesive power amounts to 130,000 lbs. and in the second to 520,000 lbs. - From all these reasonings it appears, that so much as the piece of wood is elevated towards the perpendicular, so much the nearer it approaches to its absolute strength, and by so much as the arch is flatter, or the piece of wood less inclined, the nearer it is to a straightline, and so much the more reduced to its relative strength; the position of the arch therefore must be in the ratio compounded of these two. Having established these principles, let us now shew the application in practice. Pitot’s plan of an arch, as represented in the following figure, though profuse in materials, possesses great ingenuity. The arch A C D B can be raised 30° on each side, or to the point D, without any centre. The stretcher E E is now raised and prop- ped by the struts A E, B E. The stretcher E E is divided into four equal parts; at the centre part the king post KF rises the height of the intended arch. The struts A G, B G, and the tie beam G G, are previously put in ; G G being one-half of EE. The bridles, 1, 2, 3, 4, &c. prevent the arch from yielding from A to C, or from B to D. The struts A C, B D, support the bridles 1, 1 ; 3,3;—the struts B G, A G, support the bridles 2, 2; 4,4; 5,5; 6,6;—the struts EP, D F, support the bridles 7, 7;—the struts G. H., GH, support the bridles 9, 9; and the bridles 8, 8, rest on the stretcher E. E. The struts EP, DF, support the king post, as do also the struts G. H, G H, and the king post being well secured to the stretcher E E, supports it in the centre. • This arch we will say is 60 feet span, the archstones 7 feet long, and 3 feet broad, each cubic foot of which is 160 lbs. Let the structure be of Portland stone, which weighs 160 lbs. the cubic foot. The stretcher E E may be raised 45° in the place of 30° before the centre is put up. Therefore there are only 90° of arch to provide for, and the perpendicular d, D d, determines the limits of the absolute pressure upon the frame. The parts of the arch below C and D rest upon the abutments of the pier. And the weight of one course of the archstones is 53 × 7 x 3 = 178,080 lbs. But the absolute transverse strength of a plank 7 feet long and 12 inches broad, by one thick, is 189,163 lbs. ; or if 2 inches thick, it would be no more. A plank 7 feet long and 8 inches square, has 47,649 lbs. of trans- verse strength. Therefore, the former species of scantling is the better, as it gives us an excess of 11080 lbs. more strength than is required to support that part of the arch. But 7 feet is only one-seventh part of 53 feet, the frame is therefore of sufficient strength. to support the whole weight of the arch when equally divided along its whole length. - The relative proportion of the strength of oak and fir is in therefore for every beam 8 inches square of oak, 93 by 2% of fir may be used.—From these principles of M. Pitot, every mechanic may construct the frame centre for any bridge. - In the centering of the Bridge of Carvin, as represented in the following figure, the arches are elliptical, the longer axis or span is 60 feet, the semitransverse axis or rise 20 feet, the archstones weigh 176 lbs. per cubical foot, and are 4 feet in length, which is the thickness of the arch; the truss beams were from 15 to 18 feet long and 9 inches by 8 inches broad, of oak. There were five trusses 5% feet asunder, and the whole weight of the arch amounted to 600 tons, or 112 tons for each truss; 90 tons actually pressed on each truss. But the diago- nal of the parallelogram of forces drawn for these beams, is to one of the sides as 360 to 285; them 360 : 285 : : 90 : 17+ tons on each foot or section of 144 inches. And since every square inch of oak can bear 3 tons, there were 431 tons of strength, more than six times the pressure upon the foot beams in their longitudinal direction. C E N c B N DICTIONARY OF MECHANICAL SCIENCE. 159 “In the section A C B of this figure, we have given the ºn- | ing used in erecting the bridge of Nogent, and in the section tº: used in . bridge of Maxence. They differ very jittle; but the arch of Maxence sunk 13 inches, either from the suppleness of the frame, or becºse the branches were not filled up as the work proceeded. The centre of Nogent would make a good arch for a wooden bridge, and the joints may all be secured by dove-tailed pieces; and the whole may be kept trifling annual expense. e "Pºº }; of '...i. in the following figure, the span of 120 feet has a risé of 30 feet; the arch is 5 feet thick; the strut beams 17 × 14 inches; the king post 15 × 9 inches; the Stºut beams placed in the parallel to polygons, each abutting on the king post 9 inches square. In the Bridge of Orleans, in the subjoined figure, span 100 feet, rise 30 feet, the struts A, B ; A'B', give great additional strength to the centre. - - In Blackfriars' Bridge, in the following figure, the span is 100 feet, the form elliptical, the archstones at the branch 7 feet, and decreasing to the keystone. This bridge sunk only 1; inches throughout, whereas all the French bridges we have mentioned sunk 11 inches upon an average. ---------- - - EE - - - -- - - º * - "… -- ----- 5-ºxº-º-º-º-º-º-º-º-º-º-º:-- 3:…--> --> --> -- ºrº-it-x.:--> -e ºs: - ºr sº :... →--> ÉS.--> --> --> Eºs3s: º: ~ * ~ * - : º F-3 ºr º:º 3:S→ºº-º-º:SEE:::::::--> ɺ-2 5-º-º-º-º:-- （-ºº:::::::Sº->>†<-ºº: E-º-º-º-º-º- :Fºº: ººº-ºº: Sºº-Sºº-º-º: - §: wº- :º-ºº: º:::::::::s: - -EEcº- 5 sº-ºº: ºº -> -º -------->|< *śī] s's Eºs S. §§ ‘º § 5. ES §§ S. S Sº I -S Sº S S S. s S s Sº s S’, is SH 8-S tº - S. 5. 4. - | that line or plane. The last figure represents the centering used in the con- struction of Waterloo Bridge, some further details of which we have reserved for the word IRoN BRIDGE. - - CENTRE of a Comic Section, is that point which bisects any diameter, or that point in which all the diameters intersect each other. This point in an ellipse is within the figure, in the hyperbola without, and in the parabola it is at an infinite distance. z CENTRE of Conversion, in Mechanics, a term whose signifi- cation may be thus conceived:—If a stick be laid on stagnant water, and drawn by a thread fastened to it, so that the thread makes always the same angle with it, the stick will be found to turn about a certain point; which point is called the centre of conversion. CeNTRE of a Curve, of the higher kind, is the point where two diameters concur; and when all the diameters concur in the same point, it is called the general centre. CeNT Re of a Dial, is that point where the gnomon or style, which is placed parallel to the axis of the earth, intersects the plane of the dial. CeNTRE of an Ellipse. See Centre of a Comic Section. Centre of Equant, in the old Astronomy, a point in the line of aphelion; being as far distant from the centre of the eccen- tric towards the aphelion, as the sun is from the centre of the eccentric towards the perihelion. CeNTRE of Equilibrium, is the same with respect to bodies immersed in a fluid, as the centre of gravity is to bodies in free space; or it is a certain point on which if a body, or system of bodies, be suspended, they will rest in any position. CENTRE of Friction, is that point in the base of a body, on and the mass of the body were collected, and made to revolve about the centre of the base of the given body, the angular velocity destroyed by its friction would be equal to the angular velocity destroyed in the given body by its friction in the same time. - - CeNTRE of Attraction of a body, is that point into which, if all its matter was collected, its action upon any remote particle would still be the same, as it is while the body retains its own proper form. Or, it is that point to which bodies tend by their gravity, or about which a planet revolves as a centre; being attracted or impelled towards it by the action of gravity. The common centre of attraction of two or more bodies, is sometimes | used to denote that point in which, if a particle of matter were placed, the action of each body upon it would be equal, and | where it will therefore remain in equilibrio; having no | tendency to move one way rather than another. | properly termed, by some authors, the point of equal attrac- This is more tion. CeNTRE of a Circle, is that point in a circle which is equally distant from every point of the circumference, being that from which the circle is described. CeNTRE of Gravity of any body, or system of bodies, is that point upon which the body, or system of bodies, acted upon only by the force of gravity, will balance itself in all positions; or it is a point which, when supported, the body or system will be supported, however it may be situated in other respects. Hence it follows, that if a line or plane passing through the centre of gravity be supported, the body or system will be also supported. And, conversely, if a body or system balance itself upon a line or plane, in all positions, the centre of gravity is in In a similar manner it will appear, that if a body rest in equilibrio, when suspended from any point, the | centre of gravity of that body or system is in the perpendicular | let fall from the centre of suspension; and on these principles depends the mechanical method of finding the centre of gravity of bodies. To find the Centre of Gravity of Bodies, mechanically.—For | this purpose, it is only necessary to dispose the body succes- sively in two positions of equilibrium, by the aid of two forces in vertical directions, applied in succession to two different points of the body, and the point of intersection of these two directions will shew the centre required. * - This may be exemplified by particularizing a few methods. 160 C E N C E N DICTIONARY of MECHANICAL science. If the body have plane sides, as a piece of board, hang it up by any point, then a plumb-line suspended from the same point will pass through the centre of gravity, therefore mark that line upon it; and after suspending the body, by another point, apply the plummet to find another such line, then will their intersection shew, the centre of gravity. Or thus: hang the body by two strings from the same point fixed to different parts of the body; then a plummet hung from the same point will fall on the centre of gravity. * - Another method: Lay the body on the edge of a triangular prism, or such like, moving it to and fro till the parts on both sides are in equilibrio, and mark, a line upon it close by the edge of the prism: balance it again in another position, and mark another line by the edge of the prism; the vertical line passing through the intersection of these lines, will likewise pass through the centre of gravity. The same thing may be effected by laying the body on a table, till it is just ready to fall off, and then marking a line upon it by the edge of the * table : this done in two positions of the body, will, in like man- mer, point out the centre of gravity. To find the Centre of Gravity of certain Bodies, geometrically.— Prop. 1. To find the centre of gravity of two given bodies. Let A and B be the G two given bodies, , * < AC– l—OB take A G : BG : : B : A ; so shall G be the * centre of gravity of the two bodies, as is obvious from the principle of the lever; for the bodies being suspended on the point G, they will remain in equilibrio.—in other words, the distances AG, B.G., from the common centre of gravity, are reciprocally as the weights of the bodies A and B; for, if A G = 4, B G = 6, and the ball B = 2, then the ball A = 3, because 4 : 6 : ; 2 : 3. Prop. 2. To find the centre of gravity of a triangle, A B C. Bisect any two sides, A C, CB, in the points D and E, join AE, BD, and the point of intersection G will be the centre of gravity of the triangle. This is obvious, because the triangle would balance itself on each of the lines A E, B D ; for these bisecting the line B C, A C, bisect every parallel section, and therefore the weight on each side is equal, and equally distant from these lines. - 3. To find the centre of gravity of a trapezium. Divide it into two triangles, and find the centre of gravity of each; and then, by prop. 1, the centre of gravity of these two, which will be the centre of gravity of the trapezium. And in the same manner may be found the centre of gravity of any right-lined figure. - When from the centre of gravity of any body we let fall a line perpendicular to the horizon, that line is called the line ºf direction, the property of which is, that when it falls within the base upon which the body stands, the body cannot fall, but if it falls without the base, the body will tumble. Thus, in the inclin- ing body A B, CD, as in the annexed figure, the centre ºf gravity is E, and the body stands firmly on its base, CP IK, because the line of direction EF falls within the base. But if the weight, as AB, G. H., be laid upon the top of the body, the centre of gravity is raised to L; and then, as the line of direction L. D falls without the base at D, - the centre of gravity L is not supported, and the body and weight will tumble. . Hence is obvious the danger of rising hastily in a coach or boat, when it is likely to overset. By so doing, the centre of gravity is liable to be thrown out of the base, and the vehicle or boat overset. The proper conduct of passengers in such circumstances is to lie down in the bot- tom, and bring the line of direction, and consequently the centre of gravity, within the base. Coaches are now built so as to confine the centre of grayity within the base upon the most uneven roads. The mechanical motions of animals ought to be regulated on these principles; for when the line of direction falls within the base of our feet, we stand, and most firmly, when it is in the middle of the body, as A, in the human figure; but when it is out of the base, we immedi- ately fall. When you endeavour to rise from a seat, you thrust forward your body, and draw your feet backward, tilt the vertical line from the centre of gravity falls just before your feet; this enables you to rise, and prevents you falling forward; you advance one of your feet, till the vertical line of direction is brought between your feet, in consequence of which you may stand firmly. When a man, B C, as shewn in the following figure, endeavours to walk, he first extends his hindermost leg and foot, S, almost to a straight line, and at the same time bends a-little the knee, H, of his fore leg. Thus 2 º' his hind leg is lengthened, and his P &º fore leg shortened, and by this means - & - his body is moved forward, till the RN-sº centre of gravity, V, falls beyond the § º fore foot B; and then being ready to fall, he presently prevents it, by tak- ing up the hind foot, and by bending the joints of the hip, knee, and ancle, and suddenly translating it forward to T beyond the centre of gravity, and thus he gains a new station. 2. After the same manner, by extend- 㺠ing the foot and leg H B, and thrust- § #Sing forward the centre of gravity **ś beyond the foot S; and then translat- * ºf ing the foot B forward, he gains a third station; and thus walking is continued at pleasure. His two feet do not go in one right line, but in two lines paraílel to one another; therefore, a man walking has a libratory motion from one side to the other; and it is not possible to walk in a right line. We walk on level ground easily and pleasantly; it is laborious to climb a hill, from the great flexure required of the joints to ascend, and from the stress they receive from the weight of the body in that position. In walking we always set down one foot before the other be taken up; and therefore at everº step we have both feet on the ground at once. But in running we never set one foot down till the other be up ; so that at every step we have but one foot on the ground, and all the intermediate time none. The walking of birds is not unlike that of man; only their weight is entirely supported by the strength of the muscles, since their joints are always bent. The feet of birds are also moved in two parallel lines. The motions of quadrupeds are the same as those of men. When a beast, a horse for example, stands, the line of gravity must fall within the quadrilateral made by his four feet. When he walks, he has always three feet on the ground, and one up, as you see in the figure. Thus, suppose he first lift the hind foot C. Before he does this, by extending his leg backwards, he - . t thrusts forward his body and the centre of gravity; then taking up the foot C he moves it forward to F. Then he directly takes up the fore foot B on the same side, and carries it to H; then he takes up the hind foot D, and translates it forward; and then the fore foot A ; then C again, *. and so on. : Let any person try to walk on all-fours, and one hand and one leg on one side, one hand and one leg on the other, is the natural action of the horse in walking. When the horse trots he takes up two feet together, and sets down two together, diagonally opposite. When he gallops, he takes up his feet one by one, and sets them down one by one; though some G. E. N. C E P 161 Diction ARY OF MECHANICAL SCIENCE. animals strike with the two fore feet nearly at once, and the two hind feet nearly at once ; and have not above two feet on the ground at once. Animals of six or more feet, as the cater- pillar, take up the hindmost first, then the next, and then the next in order to the foremost, all on one side; and after that, all the feet on the other side ; in the same order, beginning at the last. If the caterpillar were to take up its foremost feet first, it would move backwards, as we see a crab do on the sea- horse. . w Dogs, and other four-footed animals, find it difficult to stand upon their hind legs, as the centre of gravity, lies too far for- ward, the heads of all animals being heavy, in proportion to other parts of the body. In the duck, the goose, and the swan, who are adapted for swimming, the centre of gravity lies pretty far forward ; hence they walk awkwardly, and do not seem at ease but when in the water. Hawks have the centre of gravity so far forward, that when they light on the rocks they are obliged to stand with their heads up, somewhat in the manner of dogs. If they were to put themselves in any other position, they would ſall forward. Penguins are similarly formed, and their weight sinks them so deep in the water, that a stream passes between the neck and the body. In cats, and animals that spring upon their prey, the centre of gravity is so situated that they uni- formly fall upon their feet. When dropping from a height, they hang down the fore and hind feet and tail, so as to bring the centre of gravity to the point below their breast, which, descending first, makes them fall as they do. Fasten a piece of lead or stone to the string of a bent bow, and toss the whole in the air, that part will come down first, and the back of the bow will never do so. The same cause acts in the case of cats and other animals of prey. We are told by voyagers, and writers on natural history, that tortoises are taken in warm climates whilst floating in a drowsy state on the surface of the waves. A man throws him- self out of the boat, and lays hold of the tortoise by the tail, and by his weight keeps it from diving, which gives his com- panions time to lay hold and drag it into the boat. CeNTRE of Gyration, of a body, or system of bodies, is that point into which, if the whole mass were collected, a given force applied at a given distance from the axis of suspension, would produce the same angular velocity in the same time, as if the bodies were disposed at their respective distances. . This point differs from the centre of oscillation only in this, that in the latter case the motion is produced by the gravity of the body or of its particles, but in the case of the centre of gyration the body is put in motion by some other force acting at one place only. The distance of the centre of gyration from the axis of motion, is a mean proportion between the distance of the centre of gravity and oscillation from the same axis. Hence, when any two Gf these distances are known, the third may be readily determined. CeNTRE of Magnitude, the point equally distant from the similar external parts of a body. - - CENTRE of Motion, that point which remains at rest while all the other points of a body move about it. And this is the same in uniform bodies of the same matter throughout, as the centre of gravity. - Če NTRE of Oscillation, is that point in the axis of suspension of a vibrating body, in which if all the matter of the system were collected, any force applied there would generate the same angular velocity in a given time, as the same force at the centre of gravity, the parts of the system revolving in their respective places. Or, since the force of gravity upon the whole body may be considered as a single force, equivalent to the weight of the body, applied at its centre of gravity; the centre of oscillation is that point in a vibrating body, into which if the whole mass were concentrated, and attached to the same axis of motion, it would then vibrate in the same time the body does in its natural state. The centre of oscilla- tion cannot fall within a cone, unless the altitude be greater than the semidiameter of the cone's base; and when the altitude and semibase are equal, the centre of the base is the centre of oscillation; but when the semidiameter of the base exceeds the altitude, it always falls below the base. r T. CENTRE of Percussion, in a moving body, is that point where the percussion or stroke is the greatest, in which the whole I percutient force of the body is supposed to be collected; or about which the impetus of the parts is balanced on every side, so that it may be stopped by an immoveable obstacle at this point, and rest on it without acting on the centre of suspension. 1. When the percutient body revolves about a fixed point, the centre of percussion is the same with the centre of oscilla- tion; and is determined in the same manner, viz. by consider- ing the impetus of the parts as so many weights applied to an inflexible right line void of gravity; namely, by dividing the sum of the products of the forces of the parts multiplied by their distances from the point of suspension, by the sum of the forces. The centre of percussion in a cylinder is at 3 of its length from the point of suspension; or a stick, of a cylindrical figure, supposing the centre of motion at the hand, will strike the greatest blow at a point about two-thirds of its length from the hand. 2. But when the body moves with a parallel motion, or all its parts with the same celerity, then the centre of percussion is the same as the centre of gravity. For the momenta are the products of the weights and celerities ; and to multiply equi- ponderating bodies by the same velocity, is the same thing as to take equimultiples; but the equimultiples of equiponderating bodies do also equiponderate, therefore equivalent momenta are disposed about the centre of gravity, and consequently in this case the two centres coincide, and what is true of the one will hold in the other. - - CENTRE Phonic, in Acoustics, is the place where the speaker stands in polysyllabical and articulate echoes. CENTRE Phonocamptic, is the place or object that returns the voice. CeNTRE of Position, in Mechanics, denotes a point of any body, or system of bodies, so selected that we may properly estimate the situation and motion of the body, or system, by those of this point. It is evident, that in mechanical discus- sions, the point, by the position of which we estimate the posi- tion and distance of the whole, must be so determined that its position and distance of the whole, estimated in any direction whatever, shall be the average of the positions and distances of every particle of the mass estimated in the same direction. Accordingly, this will be the case, if the point be so selected that when a plane is made to pass through it in any direction whatever, and perpendiculars are drawn to this plane from every particle in the body or system, the sum of all the perpen- diculars on one side of this plane is equal to the sum of all the perpendiculars on the other side. k . CeNTRE of Pressure, or Meta Centre of a fluid against a plane, is that point against which a force being applied equal and contrary to the whole pressure, it will sustain it, so as that the body pressed on will not incline to either side. This is the same as the centre of percussion, supposing the axis of motion to be at the intersection of this plane with the surface of the fluid ; and the centre of pressure upon a plane parallel to the horizon, or upon any plane where the pressure is uniform, is the same as the centre of gravity of that plane. CENTRE of spontaneous Rotation, is that point which remains at rest the instant a body is struck, or about which the body begins to revolve. If a body of any size or form, after rota- tory or gyratory motions, be left entirely to itself, it will always have three principal axes of rotation, that is, all the rotatory motions by which it is effected may be constantly reduced to three, which are performed round three axes per- pendicular to each other, passing through the centre of gravity, and always preserving the same position in absolute space, while the centre of gravity is at rest, or moves uniformly forward in a right line. CeNTR e Velic, Velique, or Velic Point, is the centre of gravity of an equivalent sail, or that single sail whose position and magnitude are such as 'cause it to be acted upon by the wind when the vessel is sailing, so that the motion shall be the same as that which takes place while the sails have their usual positions. - - W- * CENTRIFUGAL PUMP, a very curious machine for raising water by means of a centrifugal force combined with the pres– sure of the atmosphere. &c. in the form of a cross, which is placed perpendicularly in It consists of a large tube of copper, the water, and rests at the bottom on a pivot. At the upper 2 T * 162 & C E T C H A Diction ARY OF MECHANICAL SCIENCE. part of the tube is an horizontal cog-wheel, which touches the cogs of another in a vertical position; so that by the help of a double winch the whole machine is moved round with very great velocity. , Near the bottom of the perpendicular part of the tube is a valve opening upwards ; and near the two extre- mities, but on the contrary side of the arms or cross part of the tube, are two other valves opening outwards. These two valves are, by the assistance of springs, kept shut till the machine is put in motion, when the centrifugal velocity of the water forces them open, and discharges itself into a cistern or reservoir placed there for that purpose. On the upper part of the arms are two holes, which are closed by pieces screwed into the metal of the tube. Before the machine can work, those holes must be opened, and water poured in through them, till the whole tube be full ; by these means all the air will be forced out of the machine, and the water supported in the tube by means of the valve at the bottom. The tube being thus filled with water, and the holes closed by the screw-caps, it is turned round by means of the winch, when the water in the arms of the tube acquires a centrifugal force, opens the valves near the extremities of the arms, and flies out with a velocity nearly equal to that of the extremities of the said arms. This machine cannot raise water higher than 32 feet; because its action depends upon the weight of the atmosphere, and, on shipboard, is much inferior to the chain-pump. - CENTRIFUGAL Force, is that force by which a body revolving about a centre, or about another body, has a tendency to recede from it. CENTRIPETAL Force, is that force by which a body is | perpetually urged onwards to a centre, and thereby made to revolve in a curve instead of a right line. CENTURY, any thing divided or ranged into periods of hundreds. Thus we say, such a century of the Christian aera, meaning so many hundred years since the commencement of that aera, and which is necessarily one more than the number of years mentioned in the date: the present is the 19th century, which commenced on the 1st of January, 1801. CEPHEUS. This constellation perpetuates the memory of an ancient king of Ethiopia, or India, said to be the father of Andromeda, and husband of Cassiopeia. Hyk (a king) was the old Ethiopian name for this asterism, which the Arabians call Keiphus, and Cheic, an evident corruption from the Greek- The boundaries and contents are: north by the pole of the world, east by Cassiopeia and Tarandus, south by Lacerta and Cygnus, and west by Draco. Right ascension 8°, and declina- tion 60° north. It contains 35 stars, viz. three of the 3d mag- nitude, seven of the 4th, &c. Alderamin, a, having 318° 33'55" right ascension, and 61° 49' 28" north declination, culminates, at London, on the first day of every month, as shewn in the following table : Meridian Altitude 79° 41' 32" north. • MonTH. CULM. MonTH. CULM. MONTH. CULM. ho. mi. ho. mi. - ho. mi. Jan. 2 36 A. May 6 34 M. Sept. 10 29 A. Feb. 12 19 A. June 4 39 M. Oct. 8 44 A. March 10 19 M. July 2 39 M. Nov. 6 59 A. April 8 29 M. Aug. 12 29 M. Dec. 4 49 A. CETUS, the Whale, is pretended by the Greeks to be the sea monster which Neptune, brother to Juno, sent to devour Andromeda, because her mother, Cassiopeia, had boasted her- self to be fairer than Juno and the Nereides; and it was placed among the stars, when Perseus, to save that princess, struck it dead, by presenting to its view the head of Medusa. The name of this constellation is found long prior to the time of Perseus. When the equinoctial sun in Aries opened the year, it was denominated the preserver or deliverer, by the idolaters of the East. The constellation of the Whale is called Nun in Chal- daic, and Nuna in Syriac. Now the head of Cetus is placed immediately under the Ram, and always rises and sets with that sign, but the rest of the constellation rises before Aries. On this account, it has been suggested, that the Ram was metaphorically called the son of that constellation, which is next to it, and which rises immediately before it.—The boundaries and contents of this constellation are: north by Pisces and Aries, east by Eridanus, Orion, and Taurus, south by Fornax Chemica and Officina Sculptoris, and west by Aqua- rius. This constellation occupies the greatest space of any in the firmament. It contains 97. stars, of which two are of the 2d magnitude, eight of the third, nine of the 4th, &c. The brilliant in this constellation is Menkar, situated in the upper' mandible, and of the 2d magnitude, having 43°12' 59' north, right ascension, and 3° 22' 50" declination north. This star appears in the horizon, at London, on E. by N. § E. point of the compass, and rises and culminates as in the following table: Meridian Altitude 41° 51' 50". - - . . . . MONTH. RISES. CULM. MonTH. RISEs. CULM. ho. mi. ho. mi. - ho. mi. ho. mi. Jan. 2 0 A. | 8 5 A. || July | 1 55 M. 8 10 M. Feb. 11 45 M. 5 53 A. Aug. 11 50 A. 6 5 M. Mar. 9 35 M. 4 4 A. || Sept. 9355 A. 4 10 M. April 7 50 M. 2 15 A. Oct. 8 10 A. 2 26 M. May | 6 0. M. 0 20 M. | Nov. 6 15 A. | 12 35 M. June 3 50 M. 10 14 M. || Dec. 4 15 A. | 10 22. A. CHAFF MACHINE, as represented in the following figure, is used for cutting straw for horses and cattle. This machine consists of a wooden frame, supported by four legs, and on this frame is a box to hold the straw, about 5 feet long and 10 inches broad. On the wheel B is fixed a knife A, and in every revolution of the wheel the knife passes the end of the box, and cuts the straw into chaff. The straw is fed by two rollers connected with the machinery in the side of the box, and worked usually by a wheel, whose teeth work in an endless screw. The whole is worked by the hand, which grasps the winch C. This is Baker's chaff-cutter. Pike's is somewhat different. w & | tol | *wº | TSS >S Ri JT | CHAIN, an instrument used in surveying, of which there are three different kinds, but that which is most commonly employed for this purpose, is the Gunter chain, so called from the name of its inventor. This chain is 4 poles, or 66 feet long, and is divided into 100 square lengths, or links, each link being 7-92 inches in a link. 1 square chain = 10000 links.- 16 poles; 10 square chains = 100000 links – 160 poles = 1 acre. - Hence we have the following easy method of converting links or chains to acres :—From the number of links point off five figures to the right hand for decimals, and those on the left will be acres; multiply the decimals by 4, and point off again five places for decimals, and those on the left will be roods; multi- ply these decimals by 40, and point off the decimals as above, and the figures on the left will be poles, or perches, which is commonly the lowest denominator. See SURV EYING. - CHAIN-PUMP, a well-known hydraulic machine for raising water. It is usually made from 12 to 25 feet in length, and consists of two collateral square barrels, and an endless chain of pistons of the same form fixed at proper distances. The chain is moved round a coarse kind of wheelwork, fixed some- times at one end, but often at both ends of the machine. The teeth of the wheelwork are so contrived as to receive one half of the flat pistons, and let them fold in ; and they take hold of the links as they rise. A whole row of the pistons (which go free of the sides of the barrel by about a quarter of an inch) are always lifting when the pump is at work; and, as this machine is generally worked briskly, the pistons or pallets bring up a full bore of water in the pump. Chain-pumps are wrought some- times by men turning winches, sometimes by horses, and some- C H A C H A 163 DICTIONARY OF MECHANICAL SCIENCE. times by the impulse of a stream of water: they are likewise so contrived, that by the continual folding in of the pistons, stones, dirt, or whatever comes in the way, may be cleared off; they are therefore often used to drain ponds, sewers, and remove foul water, when no-other pump could be employed. Chain-pumps are not merely fixed in a vertical position, but are often inclined ; and in the latter case they are in a state of the greatest perfection, or raise the most water, when the breadth of the pallets is equal to their distance from each other, and the plane is inclined under an angle of 24°21'. The Chinese method of working the chain- pump resembles the opera- tion of the tread-mill. : It is not unusual for chain- pumps to be erected without a barrel to receive the pis- tons, after the manner repre- sented in the figure. The pallets are converted into square boxes S, S, &c., which are raised by means of hexa- gonal axles, each side of the hexagon, being equal to the distance from box to box; the boxes , descend with their mouths downwards, and so enter the water. Another contrivance for raising water, similar to the chain-pump, is an endless rope, with stuffed cushions hung upon it, which, by means of two wheels or drums, are caused to rise in succession in the same barrel, and to . carry water with them. From the resemblance of this appa- ratus to a string of beads, it - . is usually called paternoster-work. But in this, as well as the chain-pump, the magnitude of the friction is a formidable practical objection. CHAINS, strong links or plates of iron, the lower ends of which are bolted through a ship's side to the timbers: they are placed at short distances from each other on the ship's outside, as being used to contain the blocks, called dead-eyes, by which the shrouds of the masts are extended. CHAIN-SHOT, a particular kind of shot, formed by fasten- ing two cannon-balls together with a short chain, and designed to mangle and ruin a ship’s sails and rigging. - CHAIN-WALES, or CHANNels, broad and thick planks projecting horizontally from the ship's outside, beginning abreast of, and continuing somewhat abaft each mast. They are formed to extend the shrouds from each other, and from the axis, or middle of the ship, so as to give a greater security and support to the masts, and to prevent the shrouds from rubbing against the gun-wale. Every mast has its chain-wales, which are either built above or below the second-deck ports in a ship of the line; they are strongly connected to the side by knees bolts, and standards, besides being confined thereto by the chains, whose upper ends pass through notches on the outer edge of the chain-wales, so as to unite with the shrouds above. CHALDRON, an English dry measure of capacity, mostly used in measuring coals. The chaldron contains 36 bushels, and weighs. about 28 cwt. By act of parliament, the Newcastle chaldron is to weigh 52% cwt., and this is to the London chal- dron in the ratio of 15 to 5, which gives 28 cwt. for the London chaldron, as above stated. - CHAMELEON, THE, in Astronomy, is a small asterism by the roots of Robur Caroli, at the south pole, and contains ten stars, none of which exceed the 5th magnitude. CHANCES, an interesting branch of the modern analysis, which treats of the probability of certain events taking place, by contemplating the different ways in which they may happen or fall. The dgetrine of chances is a subject of which the tº-ºº: S ancients seem to have had no idea; the discovery of it is wholly due to the moderns; but, like most other theories, it has grown into a science by such imperceptible degrees, that we can scarcely say to whom we are indebted for the first inven- tion. But the various circumstances and limitations under which events may happen, render it impossible to reduce the laws of chance to a few determined rules and principles, as is done in various other branches of analysis; much must neces- sarily be left to the judgment of the analyst, and no subject requires more his care and attention. We cannot in this place enter upon the subject further than to observe, that the proba- bility of casting an ace with a single die in one throw is , of casting an ace or deuce is 3, and so on. Again, the probability of drawing an ace out of a complete pack of cards is # or #. For there are four aces and 52 cards, or 4 chances for the event happening, and 52 for its happening and failing. CHANGES, in Mathematics, denote the various arrange- ments that may take place in the order or situation of a given number of things ; and is distinguished from the more general term Permutations, in this ; that in the latter there may be any number of things, and any number taken at a time; while in the former, the whole number is always supposed to enter. The whole number of changes that a given number of things n admits of, is equal to the continued product 1.2.3.4. ... n ; thus the number of changes of ...6 things = 1.2.3,4,5,6 = 720 - - 7 things = 1.2.3.4.5.6.7 = 5040 See Per MUTATION and CoM BI NAtion. - CHANNEL, in Hydrography, the deepest part of a river, harbour, or streight, which is most convenient for the track of shipping; also, an arm of the sea running between an island and the main or continent, as the British channel, &c. CHARACTERS, in Mathematics, are certain symbols intro- duced in order to represent either quantities or operations. Algebraical Characters are those used to denote operations, equalities, proportions, &c. See ALG EBRAICAL Definitions. Astronomical Characters are those used to denote the Aspects, Planets, Signs, &c. Geometrical and Trigonometrical Charac- ters. See GEOMETRY and TRI Go NoMETRY. Numeral Characters are those used to represent numbers. - CHARGE, in Electricity, in a strict sense, denotes the accu- mulation of the electric matter on one surface of an electric, as a pane of glass, Leyden phial, &c. whilst an equal quantity passes off from the opposite surface. CHARG e, in Gunnery, is the quantity of powder and ball, or shot, put into a piece of ordnance, in order to prepare it for execution. Different charges of powder, with the same weight of ball, produce different velocities in the ball, which are in the subduplicate ratio of the weights of powder; and when the weight of powder is the same, and the ball varied, the velocity produced is in the reciprocal subduplicate ratio of the weight of the ball: and thus corresponds both to theory and practice. This, however, is on a supposition that the gun is of an indefinite length ; whereas, on account of the limited length of guns, some variation from this law occurs in practice, as well as in theory; in consequence of which it appears, that the velocity of the ball increases with the charge only to a cer- tain point, which is peculiar to each gun, where the velocity is the greatest; and that, by farther increasing the charge, the velocity is gradually diminished, till the bore is quite full of powder. The length of the charge producing the greatest velocity, ought to be about #ths of the length of the bore. But for several reasons, the length of the charge producing the greatest velocity falls short of this, and the more so as the gun is the larger. From many experiments it has been found, that the length of the charge producing the greatest velocity, in guns of various lengths of bore, from 15 to 40 calibers, is as follows: Length of Charge for Length of Bore in Calibers. greatest Velocities. 15 . . . . . . . . . . . . tº º e º º ºs e e º e º & & © tº e e g c e º e s e e e º e # 20 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . # 80 . . . . . . . . . . . . . . . . . . . . . . . e e º sº e s e e º s e º e > * * * # 40 . . . . . e e e e s tº e s e e s tº e º e e s e e e s a e s e > e - e = c e s tº e # In practice, however, the charge which produces the greatest velocity, is not that which produces the greatest effect, at least in battering down the gates, &c. of fortified places, and in naval actions; for the balls, in these cases, penetrate and pass 164 G H A C. H. E. D+CTIONARY OF MECHANICAL SCIENCE. . quite through, and therefore communicate to the objects they strike against, only a part of their momentum. CHARLES’S WA IN, a name given by some old astronomical writers to the constellation Ursa Major. CHART, or SEA CHART, a hydrographical or sea map, for the use of navigators; being a projection of some part of the sea in plano, shewing the sea-coasts, rocks, sands, bearings, &c. Fournier ascribes the invention of sea charts to Henry, son of John, king of Portugal. These charts are of various kinds, the plain chart, Mercator's or Wright's chart, the globu- lar chart, &c. In the construction of charts, great care should be taken that the several parts of them preserve their position to one another, in the same order as on the earth ; and it is probable, that the finding out of proper methods to do this gave rise to the various modes of projection. There are many ways of constructing maps and charts; but they depend chiefly on two principles. First, by considering the earth as a large extended flat surface ; and the charts made on this supposition are usually, called plain charts. Secondly, by considering the earth as a sphere; and the charts made on this principle are sometimes called globular charts; Mercator's charts resemble a cylinder unrolled; and to these hydrogra- phical maps we more properly give the epithet chart. Plain CHARTs have the meridian, as well as the parallels of latitude, drawn parallel to each other, and the degrees of longi- tude and latitude every where equal to those at the equator. And therefore such charts must be deficient in several respects. For, first, since in reality all the meridians meet in the poles, it is absurd to represent them, especially in large charts, by parallel right lines. Secondly, as plain charts shew the degrees of the several parallels as equal to those of the equator, there- fore the distances of places lying east and west must be repre- sented much larger than they really are. And, thirdly, in a plain chart, while the same rhumb is kept, the vessel appears to sail on a great circle, which is not really the case. Yet plain charts made for a small extent, as a few degrees in length and breadth, may be tolerably exact, especially for any part within the torrid zone; and even a plain chart made for the whole of this zone will differ but little from the truth. Mercator’s CHART, like the plain charts, has the meridians represented by parallel right lines, and the degrees of the parallels, or longitude, every where equal to those at the equator, so that they are increased more and more, above their natural size, as they approach towards the pole ; but then the degrees of the meridians, or of latitude, are increased in the same proportion at the same part; so that the same proportion is preserved between them as on the globe itself. This chart has its name from that of the author, Girard Mercator, who first proposed it for use in the year 1556, and made the first charts of this kind, though they were not altogether on true or exact principles, nor does it appear that he perfectly understood them. Neither, indeed, was the thought originally his own, of lengthening the degrees of the meridian in some proportion; for that was hinted by Ptolemy two thousand years ago. It was not perfected, however, till about the year 1590, when Mr. Wright shewed a ready way of constructing it, by enlarging the Imeridian line by the continual addition of the secants. ... Globular CHART, is a projection so called from the conformity it bears to the globe itself. This is a meridional projection, in which the parallels are equidistant circles, having the pole for their common centre, and the meridians curvilinear and inclined, So as all to meet in the pole, or common centre of the parallels. By which means the several parts of the earth have their pro- per proportion of magnitude, distance, and situation, nearly the same as on the globe itself; which renders it a good method for geographical maps. Hydrographical CHARts, are sheets of large paper, on which several parts of the land and sea are described, with their respective coasts, harbours, sounds, flats, rocks, shelves, sands, &c.; also the points of the compass, and the latitudes and longitudes of the places. - - - - Selonographic CHARTs, are particular descriptions of the appearances, spots, and maculae of the moon. - Topographic CHARTs, are draughts of some small parts only of the earth, or of some particular place, without regard to its relative situation, as London, York, &c, - - CHEMISTRY, investigates the effects of the action of bodies upon each other, with the view of determining their constituent principles, and forming new compounds. The extensive utility of this science is shewn by its immediate connexion with the arts, subservient to the subsistence or the comforts of man. Dyeing, bleaching, tanning, glass-making, the working of metals, &c. are chemical operations. In agriculture its use is very important, because it explains the phenomena of the growth and nourishment of vegetables, and the nature and action of manures, &c. The culinary arts, the arts of baking, brewing, distilling, &c. owe their improvement to chemistry. In medicine, it affords invaluable assistance, by giving the medical man a knowledge of the various ºbstances used as medicines. In short, there is scarcely any art, trade, or manu- facture that does not depend, either immediately or remotely, upon a knowledge of this science. Besides, it enlarges the mind, by affording us a more extensive and intimate knowledge of nature, and procures for us some of the most sublime plea- sures and rational enjoyments. Before we proceed to the theory, we shall describe the principal processes employed in chemical experiments: these are— 1. Trituration. 2. Sifting. 3. Washing. 4. Filtration. 5. De- cantation. 6. Lixiviation. 7. Evaporation. 8. Distillation, 9. Sublimation. 10. Crystallization. 11. Solution. 12. Precipita- tion. 13. Fusion. 14. Cupellation. 15. Digestion. 16. Satura- tion. 17. Combustion. 18. Deflagration. 19. Detonation. 20. Operations in the dry way. 21. And in the humid way. Mechanical Operations for the Division of Bodies.—Trituration, Pulverization, and Levigation, (or the reduction of solids into powders of different degrees of fineness.) are necessary and preliminary operations, previous to the solids being chemically acted upon. Brittle substances are reduced to powder by means of hammers, pestles and mortars, and stones and mul- lers. The annexed cut represents a pestle and mortar. Fibrous substances, as wood, the horns of animals, elastic gum, and metals, which flatten under the hammer, cannot be reduced to powder by the foregoing methods; for these, files, rasps, knives, and graters, are used. - The separation of the finer parts of bodies from the Sifting. coarser, which may want farther pulverization, is performed by sifting or washing. A sieve consists of a cylindrical band of thin wood, or metal, having silk, leather, hair, or wire, plaited or woven, and stretched across it. Sieves are of different degrees of fineness. t Washing, is employed for procuring powders of an uniform fineness, more accurately than by the sieve ; but it can only be used for substances that are not acted upon by the fluid which is used in the washing. Filtration, is a finer species of sifting, through the pores of paper, flannel, fine linen, sand, pounded glass, porous stones, and the like. It is used for separating fluids from solids, or gross particles that may happen to be suspended in them, and not chemically combined with the fluids. Thus, salt water. cannot be deprived of its salt by filtration; but muddy water will deposit its mud. - Decantation, separates solid particles which are diffused through liquors. These are allowed to settle to the bottom, and the clear fluid is gently poured off. If the sediment be extremely light, and apt to mix again with the fluid by the slightest motion, a syphon is used for drawing off the clear fluid. Lixiviation, is the separation by water, or some other fluid, of such substances as are soluble in that ſluid, from other sub- stances that are not soluble in it. If a mineral consisting of Salt and sand, or salt and clay, &c. be broken to powder and thrown into water, the salt will be dissolved and kept suspended, whilst the earthy matter will fall to the bottom of the vessel, and, by means of filtration, may be separated from the fluid. Evaporation, separates a ſluid from a solid, or a more volatile fluid from another less volatile. Evaporation is used when the more volatile or fluid substance is not to be spreserved, and various degrees of heat are enployed for this purpose, accord- ing to the nature of the substances. Evaporation is performed in vessels of wood, glass, nietal, porcelain, &c. of a flat shape, to expose the liquids as extensively as possible to the action off. heat: evaporating vessels may be placed eithesover the naked G H E C H E 165 DICTIONARY OF , MECHANICAL SCIENCE. fire, or in a vessel filled with sand, called a sand-bath; or they may be left in a warm room. . . . - ... Distillation. When the fluid which is evaporated must be preserved, the operation is called distillation, which is nothing more than evaporation in close vessels, to separate two fluids of different degrees of . . . . volatility, and preserve the most volatile, or both of them. The substance to be sub- jected to distillation is . put into some vessel that will resist: the W. º, . action of heat, called a | | | | | || Üll retort. See the annexed figure, of which A is the retort, and B a vessel for receiving the product of distillation; the latter is called the receiver. a is called the turbulure, having a glass stopper, by which the substance intended for distillation is poured into the retort; b is the neck of the receiver, into which the beak of the retort enters. Alembics and stills having beaks in the same way, are used for sublimation and distillation. The vessel that contains the liquor to be distilled is placed upon the fire, or in a, - sand bath, or over a lamp ; the heat causes the volatile fluid to rise in the form of vapour and pass into the re- ceiver, where it is again condensed by cold. This con- densation may be assisted by making the vapour pass through a tube which is immersed in a vessel contain- ing cold water, and called the refrigeratory. The above represents a still in action; A is the end of the tube from whence the distilled fluid escapes. Sublimation. When the materials which are evaporated concrete in a solid form within the neck of the distilling aſ vessels, the operation is called sublima- Wi tion, and is performed in an alembic, *. which the annexed figure represents. A is the cucurbit or boiler; B is the head or capital; C is a glass tube through 'A which the sublimed substances pass into 4 D, the receiver. The following beautiful experiment, illustrated by an engraving, iſ will amply explain the operation of sub- W. limation. Procure a bell-glass, a sprig of rosemary, a flat circular piece of iron or copper, and two drachms of Benzoic acid. Heat the iron nearly to redness, sprinkle the acid on it, and invert the bell-glass, with the rosemary sprig in it, over the whole. The acid will arise or be sublimed in dense fumes, and will be precipitated or settled on the cool branches of the rosemary, in the form of a beautiful hoar frost. Crystallization. When a salt is dis- solved in water, or other fluid, and by evaporation the fluid is driven off, the salt gradually acquires a solid form, and in doing this, it arranges its particles in a particular manner; and they are then said to be crystallized. Some salts arrange themselves in the forms of pyra- mids, some of prisms of different kinds, &c. Vessels of earthenware or glass are employed for such ystallizations; and they must be kept perfectly still, and Well-defended. frºm dust or accidents. - Solution. When a salt is mixed with water, it loses its state of solidity, the particles of salt are divided, and unite themselves to those of the water, forming a liquid of which all the parts are homogeneous, or of the same kind. In this process neither the salt nor the water is decomposed, and the salt may be recovered again in its original state and quantity, by driving off the water by evaporation. The same takes place when resin is mixed with spirits of wine. The solution of metals by acids, is, however, of a different nature; here one of the substances is altered, and different products are obtained. Vessels of glass are used for solution. The liquid used for dissolving a metal, or other solid substance, is usually called a solvent. - Precipitation, is the recovery or separation of a body from its solvent, by the addition of a third substance, so that the former may re-appear in a solid state. The substance thus recovered, is called a precipitate, and the superadded body that occasions this precipitation, is called a precipitant. Fusion. The melting or causing any body to pass from the solid to the liquid state, by the action of fire, is called fusion. The fusion of metallic substances re- quires vessels which will resist de- struction by fire. Those vessels called crucibles are mostly, if not always, made of earthenware, or porcelain, or a mixture of clay and powder of black- lead. Some of these are barrel-shaped as A.; others are indented at the side, to allow their contents to be poured out, as B, and others have lids fitted to them, to prevent the sublimation or dispersion of volatile substances, such as arsenic, &c. as C. Furnaces. For fusion, we find it necessary to employ fur- naces, or the blow-pipe. The various degrees of heat required for the performance of chemical operations, render a variety of fireplaces or furnaces necessary for a chemist. Furnaces are either open at top, or covered with what is called a dome, and have a chimney or tube to carry off the heated air, smoke, &c. They are sometimes supplied with air from the natural action of the fire, which rarefies the air about the ignited fuel; and which becoming specifically lighter, ascends into the chimney, whilst the colder or heavier air is forced by the atmosphere to enter at the lower part of the furnace. Some furnaces are supplied with air by means of bellows, and those are applied to the forging of iron, or for reducing metals from their ores; - this is called smelting. Hence furnaces derive their various names, and are called simple or open furnaces, reverbe- ratory furnaces, the furnace for distilling , by a sand heat, the cupelling or enamelling § furnace, and the wind or air furnace, # which the engraving represents; a being § the ash-pit, c the fire containing a cru- § cible, d is a moveable cover, to be taken %)ſº off or put on at pleasure. There are t; also blast furnaces, forges, smelting fur- º, naces, &c. º %. For common purposes, portable fur- :: naces are used. They are extremely ... useful for a variety of purposes in the § small way; as in distillation, fusion, & : #: sublimation, cupellation, &c. &c. In the engraving of one of these furnaces, B is the fireplace, C the ash-pit, and D the chimney. Blow-pipes are used for diverting the zºº- flame of a (− candle or lamp against any bit of ore or other substance, required to be examined. They ought to have a bulb upon the middle of their stems (accord- ing to the figure) to contain the moisture that is formed from the breath. The compound gas blow-pipe,which has been 18. 166 C H I G H L DICTIONARY OF MECHANICAL SCIENCE. a late discovery, is perhaps the most generally useful instru- ment a chemist can possess. See BLoWPIPE. . Cupellation, or the art of assaying metals and ores, is per- formed in a shallow crucible made of burnt bones. The impure metal or ore is put into the cupel (of which the an- ºre nexed is a figure) with some oxidizable metal, such sº as lead. The cupel is now put into a muffle, and the § - whole is submitted to the heat of a furnace. The “ flame passes over the cupel, oxidating the lead, which combines with the base part of the metal to be assayed, and leaves the pure metal (such as gold or silver) in the shape of a button at the bottom. - Digestion. When a solid substance, in powder or other- wise, is left for a certain time in a fluid, and the mixture is kept exposed to a slow degree of heat, the process is called digestion. - - - - Saturation. When one substance which has an affinity to another, is mixed with as much of that other substance as its affinity will enable it to hold in combination, then the former substance is said to be saturated, or the mixture to have attained the point of saturation. If the mixture contain a greater proportion of either substance, it is said to contain an excess, or to be surcharged. The same thing must be under- stood of the compounds of more than two substances. Combustion, is when a body is in the act of burning in any air or gas capable of supporting flame. Deflagration, is when the combustion is attended with explo- sions or cracklings. - Detonation, is a pretty loud report. - Operations in the Dry, and Humid Way.—When strong degrees of heat are used, chemical operations are said to be performed in the dry way. The humid way is when fluids are used in the solution of bodies. - All the various parts of this science are found under their respective titles in the work, as ELEMENTs of BoD1Es, GAses, MetALs, &c. . CHERT, or CHI RK, is the name given by the miners to a siliceous slate, which is massive, not disposed to pass into thin layers, but occurring in thick beds. Colour bluish, passing into yellowish gray. Fracture splintery; edges translucent; specific gravity 2-6363. Blocks of it are used in the porcelain manufactories in the midland counties for grinding ſlint-stones for the finer porcelain, and the purity of the rock augments the product of fine siliceous earth by its own attrition during the process. There is another sort called by the miners. White Chert, which seems to be a transition of siliceous slate into quartz. It is not only used for grinding flints, but also as common millstone. A variety of chert has been found to answer as well as the best buhr stones of France in flour-mills, and is manufactured for that purpose. 50 lb. to several hundred weight each. CHESS, a game performed with different pieces of wood, on a board divided into 64 squares or houses, in which chance has so small a share, that it is a matter of doubt whether a person ever lost but by his own fault. Each player has eight dignified pieces; namely, a king, a queen, two bishops, two knights, and two rooks, also eight pawns, all of which are of two different colours, or white and black. See AUTom Aton Chess PLAYeR. - CHESNUT TRee. Next to the oak, the Spanish chesnut timber is most coveted by carpenters and joiners. It likewise makes the best stakes, pallisadoes, vine-props, hop-poles, &c. and is also proper for mill-timber and waterworks. It is like- wise fit for chests, tables, bedsteads, columns, &c. It was anciently very much used in the building of churches in this island, and must have been abundant, though now rare. The horse chesnut-tree is a very perishable wood. CHILIAD, an assemblage of several things ranged by thousands. The term was particularly applied to tables of logarithms, which were at first divided into thousands. CHILIAEDRON, a solid figure of 1000 faces. r CHILIAGON, in Geometry, a regular plane figure of 1000 sides and angles. CHIMES of A Clock, a kind of periodical music produced at equal intervals of time, by means of a particular apparatus added to the clock They may be had from CHIMNEY. The rules for building chimneys are: 1. That no timber be laid within twelve inches of the foreside of the chimney jambs. 2. That all the joists on the back be laid with a trimmer. 3. That no timber be laid within the funnel of any chimney. . CHIVALRY, in Antiquity, an institution which, according to some writers, took its rise from the crusades; but, according to others, it gave occasion to that enterprise; and which, though founded in caprice, and productive of extravagance, had a very considerable inſluence in refining the manners of the European nations, during the twelfth, thirteenth, fourteenth, and fifteenth century. Chivalry was employed in rescuing humble and faithful vassals from the º of petty lords; their women from savage lust; and the hoary heads of hermits (a species of Eastern monks, much reverenced in the Holy Land,) from rapine and outrage. In the mean time, the courts of the feudal sovereigns became magnificent and polite ; and, as the military constitution still subsisted, military merit was to be upheld; but destitute of its former objects, it naturally softened into fictitious images and courtly exercises of war, in “justs” and “tournaments;” where the honour of the ladies supplied the place of zeal for the holy sepulchre : and thus the courtesy of elegant love, but of a wild and fanatic species, as being ingrafted on spiritual enthusiasm, came to mix itself with the other characters of the knights-errant, adding gentleness to valour.—This singular institution, in which valour, gallantry, and religion, were so strangely blended, was wonderfully adapted to the taste and genius of martial nobles ; and its effects were soon visible in their manners. War was carried on with less ferocity, when humanity came to be deemed the ornament of knighthood no less than courage. More gentle and polished manners were introduced, when courtesy was recommended as the most amiable of knightly virtues. Violence and oppres- Sion decreased, when it was reckoned meritorious to check and to punish them. A scrupulous adherence to truth, with the most religious attention to fulfil every obligation, were its characteristics. - - CHLORATES, combinations of the chloric acid with oxides, alkalies, &c. CHLORIC ACID, is a combination of chlorine and oxygen, in greater abundance than in the oxide called enchlorine. By its combination with other substances, it forms the salts called chlorates, formerly denominated oxymuriates. CHLORIDES, compounds of chlorine with various other Substances. CHLORINE, formerly supposed to be a compound of oxygen and the muriatic acid, was called by the French oxy- muriatic acid gas, but Sir H. Davy having found it resisted the most powerful means used to decompose it, considered it a simple substance, and this is now the received opinion. Mix in a mortar three parts of common salt, and one of black oxide of manganese. Introduce them into a glass retort, and add two parts of sulphuric acid. Gas will issue, which must be collected in the water-pneumatic trough. This gas is of a greenish yellow colour, easily recognized by daylight, but scarcely distinguishable by artificial light. Its odour and taste are disagreeable, strong, and so characteristic, that it is impossible to mistake it for any other gas. Its specific gravity is 2-4733. In its perfectly dry state, it has no effect on dry vegetable colours. With the aid of a little moisture, it bleaches them into a yellowish white. Scheele first remarked this pro- perty; J3erthollet applied it to the art of bleaching in France, and from him Mr. Watt introduced it into Great Britain. If a lighted wax taper be immersed rapidly into this gas, it con- sumes very fast, with a dull reddish flame, and much smoke. The taper will not burn at the surface of the gas. Its taste is somewhat astringent, but not in the least degree acidulous. When we put in a perfectly dark place, at the ordinary tempe- rature, a mixture of chlorine and hydrogen, it experiences no kind of alteration, even in a great many days. But if, at the same low temperature, we expose the mixture to the diffuse light of day, by degrees the two gases enter into chemical com bination, and form muriatic acid gas. - Chlorine and Hydrogen, by their union form the muriatic acid, called also the hydrochloric acid. Some substances, when plunged into chlorine in an ignited, sºte, are speedily C H R ‘C H U 167 DICTIONARY OF MECHANICAL SCIENCE. extinguished, while others, and those the least combustible of all substances, undergo spontaneous combustion. Several of the metals, and gold itself when plunged into it, burst into actual flame, and burn with great brilliancy. CHLORITES, a kind of green jasper, almost as pellucid as the coarser emeralds. It is sometimes amorphous, and some- times crystallized. There are four species, viz. the earthy chlorite, common chlorite, the foliated, and schistose chlorite. CHOCOLATE, a sort of cake made chiefly from the cocoa- nut. When the cocoa is properly roasted and cleansed, it is pounded in a mortar, and afterwards ground on a stone. It is then put hot into tin moulds, in which it soon congeals. The Spaniards mix with the cocoa-nuts, cloves, cinnamon, and other ingredients; but in England, the chocolate is made of simple coGoa, with a little sugar and vanilla. CHOLERA MORBUS, a sudden effusion or overflowing of the bile on the stomach or intestines; and its symptoms are, violent retching, and in some cases, purging. CHOLOSTERIC Acid, is, obtained from cholosterine by heating it with strong nitric acid. CHOLOSTERINE, the name given to the pearly substance of human biliary calculi. CHORD, in Geometry, is the right line joining the extremi- ties of any arc of a circle ; such are the lines A B, D C.—1. A line drawn from the centre to bisect a chord, is perpen- dicular to the chord; or if it be perpen- dicular to the chord, it bisects both the chord and the arc of the chord, as O E; O E. 2. Chords which are equally distant from the centre of a circle, are equal to each other; or if they are equal to each other, they are equally distant from the centre. 3. The chord of an arc is a mean proportional between the diameter and versed sine of that arc. * , Line of CH oftDs. See Plane ScAle and Sector. . CHORD, or Cord, in Music, denotes the string or line, from the vibration of which the sensation of sound is excited ; and by whose divisions the several degrees of time are deter- mined. CHOROGRAPHY, the act of making a map of a particular country or province. . - - CHORUS, in Music, is when, at certain periods of a song, the whole company are to join the singer in repeating certain couplets or verses. - CHROMATICS, that part of the science of optics by which the properties of the colours of light, and of natural bodies, are illustrated and explained. CHROMIC ACID has been obtained from red oxide of lead, ore of Siberia, and from an ore of iron from the department of War in France. It has the property of colouring its salts, and hence it has been called chromic. If two parts of the red lead ore of Siberia, in fine powder, be boiled with one of an alkali saturated with carbonic acid, in forty parts of water, a carbo- nate of lead will be precipitated, and the chromate remain dissolved. The solutions are of a lemon colour, and afford crystals of a somewhat deeper hue. Those of chromate of ammonia are in yellow laminae, having the metallic lustre of gold. The chromate of barytes is very little soluble, and that of lime still less. They are both of a pale yellow, and when heated give out oxygen gas, as do the alkaline chromates. CHROMEUM, a very rare metal, found either in the form of chromate of lead, or of chromate of iron. The emerald of Peru, and spinel ruby, owe their colours to this metal. Chro- mium is obtained from its native combinations by decomposing them by the alkaline carbonates, precipitating the chromic acid, and heating it strongly in a crucible. Chromium is a porous mass of agglutinate grains, brittle, of a white between tin and steel. Specific gravity 5-9. It is susceptible of a small degree of magnetism. It resists all the acids, except the nitro- muriatic. CHRONOLOGY, is that science which treats of time, and shews its different measures or computations, as they have been observed by different nations. By chronology we are enabled truly to date the beginning and end of the reigns of princes, the pirths and deaths of eminent persons, the revo- lutions of empires and kingdoms, battles, sieges, or any other remarkable events. Without this useful science, that is to say, without distinguishing the times of events as clearly as the nature of the case will admit, history would be little better than a heap of confusion, destitute of light, order, or beauty. See TIME, Ye AR, AERAs, &c. CHRONOMETER, in general, means an instrument used in measuring time, as dials, clocks, watches, &c. The term, however, is commonly used for a machine so contrived as to measure a small portion of time with great exactness, even to the sixteenth part of a second, and which is of great use in astronomical observations, ascertaining the time of the fall of bodies, the velocity of running waters, &c. The lamp chrono- meter consists of a chamber lamp, or a cylindrical vessel about three inches high, and one inch diameter. To the stand is fixed a handle, which supports a frame, covered with oiled paper, about 12 inches high, and 4 wide. This frame is divided into 12 equal parts by horizontal lines, at the ends of which are marked the hours, and between the lines are diagonals divided into halves, quarters, &c. On the handle, and next to the glass, is fixed a stile, and as the distance of this stile from the flame of the lamp is only half an inch, if the distance of the frame from the stile be 6 inches, then while the float containing the light descends by the decrease of the oil, one inch, the shadow of the stile on the frame will ascend 12 inches, and thus shew, by its progression, the increase of the hours with the several divisions. The oil must be very pure, and the wick of the same size and substance. CHRYSALIS, or AURELIA, in Natural History, denotes the state of seeming insensibility, in which butterflies, moths, and some other insects, pass through before they arrive at their winged or perfect state. The figure of the chrysalis is gene- rally conical ; and the creature, when in this state, seems to have neither legs, wings, nor motion. It is almost destitute of life, for it takes no nourishment, nor has it apparently any organs for the purpose. The external covering of the chrysalis is membraneous, smooth, and glossy, but some of them have hairs; and others are rough all over like shagreen. They are divided generally into two classes, the round, and the angular, and of these again there are several subordinate distinctions. Some of them are very beautiful. The time of the animal in the chrysalis state varies in different species, some being no more than eight days, while others are as many months. CHRYSOLITE, in Natural History, a gem to which the ancients gave the name of topaz; their true chrysolite being that which modern jewellers call topaz. The chrysolite is found in angular fragments and crystallized. It is of a green colour, and there are two varieties, 1, the common chrysolite, found in Ceylon, South America, and Bohemia : its colour is a yellowish green. 2. Olive chrysolite, is found commonly in basalt, and is of an olive-green colour. CHRYSOPRASE, a mineral found in Germany, and which is always amorphous. It is of a green colour, and splintery.— Also, a variety of chalcedony used in jewellery. It consists of 90 silica in the 100. CHRYSOPRASUS, in Christian Antiquity, the tenth of those precious stones which adorned the foundation of the hea- venly Jerusalem: the colour of it was green, inclining to that of gold, as its name imports. See Revelation, chap. xxi. 20. CHURCHWARDENS, the guardians or keepers of the church, are persons annually chosen in Easter week, by the joint consent of the minister and parishioners—or according to the custom of the respective places—to look after the church and churchyard, and things thereunto belonging. They are intrusted with the care and management of the goods and personal property of the church, which they are to order for the best advantage of the parishioners ; but they have no interest in, or power over, the freehold of the church itself, or of any land or other real property belonging to it: these are the pro- perty of the parson or vicar, who alone is interested in their loss or preservation. The churchwardens, therefore, may pur- chase goods and other articles for the use of the parish; they may, likewise, with the assent of the parishioners, sell or other- wise dispose of the goods of the church; but without such con- sent, they are not authorized to alienate any of the property under their care. - . . . - 168 C I. M. C H U DICTIONARY OF MECHANICAL SCIENCE. * All peers of the realm, clergymen, counsellors, attorneys, The above description answers to the most simple form of the circumferentor; but an improved instrument of this kind is sold by Jones, of Holborn, which in some measure answers the purpose of a theodolite. - CIRCUMGYRATION, the whirling motion of a body about a centre. CIRCUM-Pol AR Stars, are those situated near the north pole of the heavens, or those which revolve about it without setting. - CIRCUMSCRIBED FIGURE, is that which is circumscribed or drawn about another figure, so as to touch it on every side. A right-lined figure is said to be circumscribed about another, when all the angles of the latter fall in the sides of the former. A right-lined figure circumscribes a curvilinear one, when the periphery of the latter touches all the sides of the former. A circle, or other curvilinear figure, circumscribes a right-lined one, when all the angles of the latter are in the periphery of the former. C1R cu MscRIBED Hyperbola, one of Newton’s hyperbolas, of the second order, which cuts its asymptotes, and contains the part cut off within itself. CIRCUMVALLATION, in military affairs, is a fortification of earth, consisting of a parapet and trench made round a town intended to be besieged, when opposed to any army that may come to its relief. CIRRI, in botanical language, denotes the fine strings or filaments by which creeping plants adhere to walls and trees. In ichthyology, the term is applied to appendages hanging from the mouths of fishes, and called by some, beards. CISSOID of Diocles, in the higher Geometry, is a curve line of the second order, invented by Diocles, an ancient Greek geometrician, for the purpose of find- ing two continued mean pro portionals between two other given lines. The generation of this curve is as follows: D At the extremity B of the diameter A B of the circle A O B, draw perpendicular to it the indefinite line C B D, to which from the other extremity A draw several limes cutting the circle in I, O, N, &c. and upon these lines set off the corresponding equal distances, viz. H M - A I, FO = A O., C L = A N, &c.; then the curve line B, El N & 9 drawn through all the points M, O, L., &c. is the cissoid. Other methods of constructing this curve may be seen in Newton's “ Universal Arithmetic,” and Emerson on “Curve Lines.” CISTERN, on board of ships, is a large wooden trough, placed in the well just below the orlop, and having a leaden | pipe, which goes through the ship's side, whereby it is occa- sionally filled with sea water, which is thence pumped up to wash the decks, &c. - - - CISTUS, the Rock Rose, a genus of the monogynia order, in the polyandria class of plants, ranking in the natural method under the 20th order, rotaceae. There are 66 species, mostly natives of the southern parts of Europe. They are very beau- tiful evergreen shrubs, and very ornamental in gardens. The flowers are white, purple, and yellow ; they are propagated by seeds or cuttings. Gum labdanum is obtained from the species in the Levant. CITADEL, a place fortified with four, five, or six bastions, on a convenient hill, near a city which it commands. CITATION, in ecclesiastical courts, is the same with a summons in the civil. - CITRUS, the citron, orange, and lemon tree, a genus of the polyadelphia class, and icosandria order of plants. Calyx quinquefid ; petals oblong, and five ; antherăe twenty; filaments unite into various bodies; fruit nine-celled. ' There are five species, and many varieties. 1. Citrus aurantium, the orange, of which the varieties are, the Seville orange, a handsome tree, and the hardiest of any. The fruit is large, rough-rinded, and sour. 2. The China orange, which has a smooth, thin rind, and sweet fruit. 3. The forbidden fruit-tree, very much resembles the common orange-tree, but the fruit is large ; the flavour is delicious. 4. The horned orange, is a tree of moderate size, producing fruit which divide, and the rind has divisions like horns. 5. The hermaphrodite orange produces fruit formed partly like that of the orange, and partly like a citron. 6. The dwarf orange tree, or nutmeg orange, grows to the height of two or three feet, and the fruit is very small. II. Citrus medica, the citron tree, of which there are six varieties. The lemon tree is accounted a variety of the citron, and of this there are not less than eleven sorts. Besides these varieties of the citrus there are several others, as, 1. The citrus trifoliata, a thorny shrub, which grows in Japan. 2. Citrus décumana, or shaddock, which is a native of the East and West Indies. 3. Citrus Japonica, the fruit of which is about the size of a cherry, and very pleasant to the taste. CIVET, is collected betwixt the amus and the organs of gene- ration of a fierce carnivorous quadruped, met with in China, and the East and West Indies, called a civet cat; but bearing a greater resemblance to a fox or marten than a cat: it is a species of Viverra. Several of these animals have been brought into Holland, and afford a considerable branch of commerce, particularly at Amsterdam. The civet is squeezed out in summer every other day; in winter twice a week : the quantity procured at once, is from two scruples to a drachm, or more. The juice thus collected is much purer and finer than that which the animal sheds against shrubs or stones in its native climates. Good civet is of a clear yellowish or brownish colour, not fluid, nor hard, but about the consistence of butter or honey, and uniform throughout; of a very strong smell; quite offensive, when undiluted; but agreeable, when only a small portion is mixed with other substances. CIVIL DAY, like the astronomical or natural, consists of twenty-four hours, but begins differently in different nations. The ancient Babylonians, Persians, Syrians, and most of the eastern nations, began their day at sun-rising. The ancient Athenians, the Jews, &c. began their day at sun-setting, which custom is followed by the modern Austrians, Bohemians, Sile- sians, Italians, Chinese, &c. The Arabians begin their day at noon, like the modern astronomers. The ancient Egyptians, Romans, &c. began their day at midnight, and this method is followed by the English, French, Germans, Dutch, Spanish, and Portuguese. - CIVILIAN, a term applied to the doctors and professors of the civil law. In London they have a college, called Doctors’ Commons. * CIVIL LAW, is properly the peculiar law of a state, coun- try, or city, but is now applied exclusively to a body of laws compiled out of the best Roman and Grecian systems of 172 C L I C L E DICTIONARY OF MECHANICAL SCIENCE. jurisprudence, agreeable to what is denominated the law of nature and nations, and which were generally observed throughout the Roman dominions above 1200 years. In our country, the civil law is used in the ecclesiastical courts and the admiralty, but is subservient to the common law. CIVIL YEAR. See Ye A R. CLAMPS, in Naval Architecture, thick planks on the inner part of a ship's side, used to sustain the ends of the beams, and extending from stem to stern, including the whole interior range of the side. They are placed close under each deck, so as to be securely fayed to all the timbers, to which they are fastened by nails through the clamp, and penetrating two-thirds of the thickness of the timbers. The clamps of the lower and second decks ought to be equal in thickness to half the corresponding timbers in that part, and as broad as can be procured. In their disposition it is essentially necessary to avoid their being wounded by the ports, as the strength and firmness of a ship greatly depend on the substance and solidity of those pieces which lie horizontally in her frame. CLAMPs are also smooth crooked plates of iron fore-locked upon the trunnions of the cannon, to keep them fast upon their carriages: these, however, are more properly, termed cap- squares. Clamps of the latter kind are likewise frequently used to fasten the masts or bowsprits of small vessels, and of boats. CLAN, a term used in Scotland to denote a number of fami- lies of the same name, under a feudal chief, who protected them, and in return for that protection commanded their services as his followers, and led them to war, and on military excursions. . . CLARENCIEUX, the second king at arms, so called from Lionel Duke of Clarence, to whom the title originally apper- tained. His office is to marshal the order of procession in the funerals of the inferior nobility, &c. CLARIFICATION, in Chemistry, the clearing and fining any fluid from heterogeneous matter. CLARO OBSCURO, in Painting, the art of distributing advantageously the light and shadow of a piece with regard to the ease of the eye, and the effect of the whole. It also denotes a design consisting of only two colours, usually black and white, or black and yellow. CLASS, a term given to the general divisions of a subject: thus in the Linnaean system, animals and plants are divided into classes. - CLAY, a kind of earth, which was formerly denominated argillaceous, but is now found to be a mixture of alumina and silica in various proportions. Clay also contains carbonate of lime, of magnesia, barytes, oxide of iron, &c. It adheres slightly to the tongue; feels greasy; and falls to powder in water. When pure, it is white with a tinge of blue or yellow. Potters’ clay stains the fingers, and acquires a polish by rub- bing. When properly moistened, it is very ductile. Tobacco pipe clay is a variety of this species. The structure of schis- tose clay is slaty, and of a gray colour. It is usually found in coal mines. CLAY SLATE, is a mineral extensively distributed, forming part of primitive and transitive mountains. Its constituents are 48-6 silica, 23:5 alumina, 1.6 magnesia, 11-3 peroxide of iron, 0.5 oxide of manganese, 4.7 potash, 6-3 carbon, 0.1 sul- phur, and 7-6 water and volatile matter. CLEATS, pieces of wood of different shapes, used occa- sionally in a ship, to fasten ropes upon : some have one, and some two arms; others are without arms, being hollowed in the middle to tie any thing to, and are called belaying cleats, a deck cleat, and a thumb cleat. CLEF, or Cliff, in Music, a mark set at the beginning of a song, denoting the key in which the same is to be performed, or it is a letter marked on a line, to explain the rest. CLEOSTRATUS, a celebrated astronomer, born in Tenedos, was, according to Pliny, the first who proposed the signs of the zodiac; others say, that he only invented the signs Aries and Sagittarius. He also corrected the errors of the Grecian year, about the 306th before Christ. - CLEPSYDRA, an instrument or machine serving to measure time §y the fall of a certain quantity of water, though there have likewise been clepsydrae made with mercury. The Egyp- tians, by this machine, measured the course of the sun. Tycho Brahe, in later days, made use of it to measure the motion of the stars, &c.; and Dudley used the same contrivance in making all his maritime observations. The use of clepsydrae is very ancient; they were invented in Egypt, under the Ptole- mies; as were also sun-dials. Their use was chiefly in the winter, as the sun-dials served in the summer : but they had two great defects; the one, that the water ran out with a greater or less facility, as the air was more or less dense; the other, that the water ran more readily at the beginning than towards the conclusion. The Construction of a common Clepsydra.-To divide any cylindrical vessel into parts, to be emptied in each division of time ; the time wherein the whole, and that wherein any part is to be evacuated, being given : Suppose a cylindrical vessel, whose charge of water flows out in twelve hours, were required to be divided into two parts, to be evacuated each hour. T. As the part of time 1 is to the whole time 12, so is the same time 12 to a fourth proportional 144. 2. Divide the altitude of the vessel into 144 equal parts: here the last will fall to the last hour; the three next above to the last part but one ; the five next to the tenth hour ; lastly, the twenty-three last to the first hour. For since the times increase in the series of the natural numbers 1, 2, 3, 4, 5, &c. and the altitudes, if the numeration be in a retrograde order from the twelfth hour, increase in the series of the unequal numbers 1, 3, 5, 7, 9, &c. the altitudes computed from the twelfth hour will be as the squares of the times 1, 4, 9, 16, 25, &c. Therefore the squares of the whole time, 144, comprehend all the parts of the altitude of the vessel to be evacuated. But a third proportionai to 1 and 12 is the square of 12, and consequently it is the number of equal parts in which the altitude is to be divided, to be distributed accord- ing to the series of the unequal numbers, through the equal interval of hours. There were many kinds of clepsydrae among the ancients; but they had all this in common, that the water ran generally through a narrow passage, from one vessel to another, and in the lower was a piece of cork or light wood, º as the vessel filled, rose up by degrees, and shewed the O II. T. Clepsydrae have been much improved of late years in their construction; but as their use is now superseded by the accuracy of our modern timepieces, we shall not dwell longer upon them here. CLERK, a word originally applied to a clergyman, from the Greek k\mpoc, chosen, whence it was afterwards used to denote a man of learning. In our law, it is still the designation of every person in holy orders under the episcopal dignity. The word clerk is now variously applied to persons in numerous offices in the law and the government, as well as to those employed in keeping merchants’ books. CLICKS are small pieces of iron falling into a notched wheel attached to the winchers in cutters, &c. and thereby serving the office of pauls. CLIMATE, or CLIME, in the ancient Geography, a part of the surface of the earth, or zone, bounded by two lesser circles parallel to the equator; and of such a breadth, as that the longest day in the parallel nearer the pole exceeds the longest day in that next the equator, by some certain space, as half an hour or an hour. Vulgarly, the term climate is bestowed on any country or region differing from another, either in respect of the seasons, the quality of the soil, or even the man- ners of the inhabitants, without any regard to the length of the longest day. CLINCH, a particular method of fastening large ropes by a kind of knot and seizings, instead of splicing; and is chiefly used to fasten the cable to the ring of the anchor, and the breechings of guns to the ring-bolts in the ship's side. CLINCHER-WORK, the disposition of the planks in the side of any boat or vessel, when the lower edge of every plank Overlays that next below it, like slates on the roof of a house. CLINCH ER-BUILT, made of clincher-work. CLINCHING, in sea language, is the driving a little oakum into the seams to keep out the water. CLINICAL, in Medicine, is applied to the practice of visiting and treating patients. - C L O C L O I73 DICTIONARY OF MECHANICAL SCIENCE. CLOCK, a machine now constructed in such a manner, and so regulated by the uniform motion of a pendulum, as to mea- sure time, and all its subdivisions, with great exactness. Before the invention of the pendulum, a balance, not unlike the fly of a kitchen jack, was used instead of it. Clocks were at first called nocturnal dials, to distinguish them from sun-dials, which shewed the hour by the shadow of the sun. The inven- tion of clocks with wheels is ascribed to Pacificus, archdeacon of Verona, in the 9th century, on the credit of an epitaph quoted by Ughelli, and borrowed by him from Panvinius. Others attribute the invention to Boethius, about the year 510; and some to Archimedes. But we know for certain, that Edward III. gave permission to three artists to come over from Holland to England, and practise their calling here. A modern clock, as in the figure, consists of a variety of parts, which may be thus explained : P is a weight which is suspended by a cord that winds about the cylinder or barrel C, which is fixed upon the axis a, a ; the pivots b, b, go into holes made in the plates TS, TS, in which they turn freely. These plates are made of brass or iron, and are connected by means of four pillars, Z, Z; the whole together being called the frame. The weight P, if not restrained, would necessarily turn the barrel C, with an uniformly accelerated motion, in the same manner as if the weight were S - falling freely. But the barrel is furnish- ed with a ratchet- wheel, K, K, the right side of whose teeth strikes against the click, which is fixed with a screw to the _d | ITTI wheel D D, as repre- }; sented in the second # E: figure; so that the action of the weight is communicated to the wheel D D, the teeth of which act upon d the teeth of the small wheel d, which turns upon the pivots c, c. *Z The communication or action of one wheel with another, is called Q. Z, 1 ti the pitching ; a small | wheel like d is called a pinion, and its teeth - —rſ f are called leaves of 1UZ |t , the pinion. Several TU - things are requisite to form a good pitch- ing, the advantages of which are obvi- ous in all machinery IP where teeth and pi- nions are employed. The teeth and pinion-leaves should be of a proper shape, and E N. Dr. JR- = perfectly equal among themselves: the size also of the pinion. should be of a just proportion to the wheel acting into it. The wheel EE is fixed upon the axis of the pinion d'; and the notion communicated to the wheel D D by the weight is transmitted to the pinion d, consequently to the wheel E E, aS likewise to the pinion e and wheel FF, which moves the punion f, upon the axis of which the crown or balance-wheel G.H is fixed. The pivots of the pinion f play in holes of the plates LM, which are fixed horizontally to the plates T.S. In a word, the motion begun by the weight is transmitted from the wheel G H to the palettes I K, and by means of the fork U X riveted on the palettes, communicates motion to the pendulum A. B. which is suspended upon the hook A. The pendulum A B describes, round the point A, an arc of a circle alternately going and returning. If, then, the pendulum be once put in motion by a push of the hand, the weight of the pendulum at B will make it return upon itself, and it will continue to go alter- nately backward and forward till the resistance of the air upon the pendulum, and the friction at the point of suspension at A, destroys the original impressed force. But as at every vibra- tion of the pendulum the teeth of the balance-wheel G H act So upon the palettes I K (the pivots upon the axis of these palettes play in two holes of the potence st,) that after one tooth H has communicated motion to the palette K, that tooth escapes; then the opposite tooth G acts upon the palette I, and escapes in the same manner; and thus each tooth of the wheel escapes the palettes I K, after having communicated their motion to the palettes in such a manner that the pendu- Jum, instead of being stopped, continues to move. The wheel E E revolves in an hour; the pivot c of this wheel passes through the plate, and is continued to r ; upon the pivot is a wheel N N, with a long socket fastened in the centre; upon the extremity of this socket r, the minute-hand is fixed. The wheel N N acts upon the wheel O ; the pinion of which p acts upon the wheel g g, fixed upon a socket which turns along with the wheel N. This wheel g g makes its revolution in 12 hours, upon the socket of which the hour-hand is fixed. - From the above description it is easy to see, 1. That the weight P turns all the wheels, and at the same time continues the motion of the pendulum. 2. That the quickness of the motion of the wheels is determined by that of the pendulum. 3. That the wheels point out the parts of time divided by the uniform motion of the pendulum. ſºn D Uğ When the cord upon which the weight is suspended is entirely run down from off the barrel, it is wound up again by means of a key, which goes on at the square end of the arbor at Q, by turning it in a contrary direction from that in which the weight descends. For this purpose the inclined side of the teeth of the wheel K (as in the annexed figure) removes the click C, so that the ratchet-wheel R. - § turns while the wheel D is at rest; but º | ſº as soon as the cord is wound up, the º Ş " click falls in between the teeth of the º º wheel D, and the right side of the teeth | D º ( again act upon the end of the click, º | º ū which obliges the wheel D to turn along | | lº with the barrel; and the spring A keeps i | º º Ø the click between the teeth of the ratchet- K wheel R. ... We shall now explain how time is measured by the motion of the pendulum; and how the wheel E, upon the axis of which the minute-hand is fixed, makes but one precise revolution in an hour. The vibrations of a pendulum are performed in a shorter or longer time in proportion to the length of the pendulum itself. A pendulum of 39% inches in length makes 3600 vibra- tions in an hour; i. e. each vibration is performed in a second of time, and for that reason it is called a second pendulum. But a pendulum of 9; inches makes 7200 vibrations in an hour, or two vibrations in a second of time, and is called a half-second pendulum. Hence, in constructing a wheel whose revolution must be performed in a given time, the time of the vibrations of the pendulum which regulates its motion must be considered. Supposing, then, that the pendulum A B makes 7200 vibrations in an hour, let us consider how the wheel E shall take up an hour in making one revolution. This entirely depends on the number of teeth in the wheels and pinions. If the balance- wheel consists of 30 teeth, it will turn once in the time that the pendulum makes 60 vibrations; for at every turn of the wheel the same tooth acts once on the palette I, and once on the palette K, which occasions two separate vibrations in the pen- dulum ; and the wheel having 30 teeth, it occasions twice 30, or 60 vibrations. Consequently this wheel must perform 120 revo- lutions in an hour; because 60 vibrations, which it occasions at every revolution, are contained 120 times in 7200, the num- ber of vibrations performed by the pendulum in an hour. Now, in order to determine the number of teeth for the wheels EF, and their pinions ef, it must be remarked, that one revolution of the wheel E must turn the pinion e as many times as the num- ber of teeth in the pinion is contained in the number of teeth in the wheel. Thus, if the wheel E contains 72 teeth, and the pinion e 6, the pinion will make 12 revolutions in the time that the wheel makes 1; for each tooth of the wheel drives forward a tooth of the pinion, and when the 6 teeth of the pinion are moved, a complete revolution is performed; but the wheel B 2 Y - 474 G. L. Q Ú L. O. ‘DICTIONARY OF ME&HANICAL SCIENGE. has by that time only advanced 6 teeth, and has still 66 to advance before its revolution be completed, which will occasion 11 more revolutions of the pinion. For the same reason, the wheel F having 60 teeth, and the pinion f6, the pinion will \make 10 revolutions while the wheel performs 1. Now the wheel F being turned by the pinion e, makes 12 revolutions for one of the wheel E.; and the pinion f makes 10 revolutions for one of the wheel F ; consequently the pinion fperforms 10 times 12, or 120 revolutions, in the time the wheel E performs one. But the wheel G, which is turned by the pinion f, occasions 60 vibrations in the pendulum each time it turns round ; conse- quently the wheel G occasions 60 times 120, or 7200, vibrations of the pendulum while the wheel E performs one revolution; but 7200 is the number of vibrations made by the pendulum in an hour, and consequently the wheel E performs but one revo- lution in an hour; and so of the rest. From this reasoning, it is easy to discover how a clock may be made to go for any length of time without being wound up. 1. By increasing the number of the teeth in the wheels. 2. By diminishing the number of teeth in the pinions. 3. By increas- ing the length of the cord that suspends the weight. 4. By in- creasing the length of the pendulum. And, 5. By adding to the number of wheels and pinions. But in proportion as the time is augmented, if the weight continues the same, the force which it communicates to the last wheel GH will be diminished. It only remains to take notice of the number of teeth in the wheels which turn the hour and minute hands. The wheel E performs one revolution in an hour; the wheel N N, which is turned by the axis of the wheel E, must likewise make only one revolution in the same time; and the minute-hand is fixed to the socket of this wheel. The wheel N has 30 teeth, and acts upon the wheel O, which has likewise 30 teeth, and the same diameter; consequently the wheel G. takes an hour to a revolu- tion: now the wheel O carries the pinion p, which has 6 teeth, and which acts upon the wheel q q of 72 teeth; consequently the pinion p makes 12 revolutions while the wheel q q makes one, and of course the wheel qq takes 12 hours to one revolution; and upon the socket of this wheel the hour-hand is fixed. Much that has been said here concerning revolutions of wheels, &c. is equally applicable to watches as to clocks. But to speak of the striking part, in which, indeed, as well as the other part of a clock, there is room for a great variety and choice in the construction; the wheels composing this part are, the great or first wheel, moved by the weight or spring at the barrel, in sixteen or thirty hour clocks; this has usually pins, and is called the pin-wheel: in eight-day pieces the second wheel is commonly the pin-wheel or striking-wheel, which is rmoved by the former. wheel, or hoop-wheel, having a hoop almost round it, wherein Next to the striking-wheel is the detent- $ t is a vacancy at which the clock locks. The next is the third or fourth wheel, according to its distance from the rest, called the warning-wheel. The last is the flying pinion, with a fly or fan, to gather air, and so bridle the rapidity of the clock's motion. To these must be added the pinion of report, which drives round the locking-wheel, called also the count-wheel, ordinarily with eleven notches in it, unequally distant, to make the clock strike the hours. Besides the wheels, to the clock part belongs the rash or ratch ; a kind of wheel with twelve large fangs, running concentrical to the dial-wheel, and serving to lift up the detents every hour, and make the clock strike: the detents or stops, which being lifted up and let fall, lock and unlock the clock in striking ; the hammer, which strikes the bell ; the hammer tails, by which the striking pins draw back the hammers; latches, whereby the work is lifted up and unlocked ; and lifting-pieces, which lift up and unlock the detents.--For the other parts of a clock, see BALANCE, PENDU- ‘LUM, and Scape MENT. J. H. G. Dyar, of Vermont, in America, has invented a clock, the principles and movements of which entirely differ from those at present in use. The pendulum moves in a cycloidal arch, and performs long and short vibrations in equal times; while the pendulum of the common clock swings in the arc of a circle, making unequal vibrations in unequalitimes. In other respects its constructionis peculiar; the hammer, which is balanced and turns on a pivot, strikes the internal limb of the bell; and the maditinery of the whole is surprisingly simple, but two wheels . being required to continue the operation of eight days, without renewing the power: three wheels, it is said, will do this for a year; and four, we are told, will perpetuate the motion for a century. They may be seen at some of the clockmakers in London. - Prior's contrivance for the striking part of a eight day clock, consists of a wheel, on the face of which are cut six turns of a spiral line for counting the hours; the pins below this spiral elevate the hammer, and those above are for the use of the detent. This single wheel serves the purpose of count-wheel, pin-wheel, detent-wheel, and the fly-wheel, and has six revo- lutions in striking the 12 hours. The flies of clocks turn round, at a mean, above sixty times for every knock of the hammer, but this turns round only three times for the same purpose ; and suppose the pivots were of equal diameters, the influence of oil on them would be as the number of revolutions in each. In some parts of the kingdom, Glasgow to wit, the dials of public clocks have been illnminated by gas ; and certainly nothing is more necessary than this addition to our night watch. A dial-plate might be made to revolve on the axis of the fixed dial. The figures shewing the hours being cut in contrary succession, and the span illuminated by a strong gas light. One on the following plan might be adopted, exactly as it has been suggested by the editor of the “Register of the Arts and Sciences.” A is the dial-plate of a common clock, with the hours, &c. marked upon it, as usual ; B is the proposed addition to it, for the pur- pose of exhibiting the time distinctly during the night; C is a light cog-wheel, placed immediately behind the day dial, having its centre fitted in the arbor of the hour-hand, and revolv. ing with it. The night dial B we propose to be made of a plate of glass, with the hours painted upon itin black, and to revolve on an axis in its centre. The index, repre- sented by an arrow, is fixed. The periphery of the glass plate is encompassed by a rim of brass, having cogs in - - its outer edge, which fit into the cogs of the wheel C ; consequently they move together; and being of equal diameters, they perform their revolutions in equal time. The time represented in our engraving is a quar- ter past ten ; when the hour-hand has moved on to XI, (for instance,) the transparent dial B will have moved an equal space past the fixed index, and denote the same precise time. Both dials must, by this simple contrivance, invariably agree in their respective indications of the time. During the day the time is observed on the large dial, as usual; and at night a lighted lamp placed behind the transparent dial will always exhibit the time as distinctly. CLOSE-HAULED, the arrangement or trim of a ship's sails when she endeavours to make a progress in the nearest direc- tion possible towards that point of the compass from which the wind blows; in this manner of sailing, the keel of square-rigged vessels commonly makes an angle of six points with the line of the wind, but cutters, luggers, and other fore-and-aft rigged vessels, will sail much nearer. All vessels, indeed, are sup- posed to make nearly a point of lee-way when close-hauled, even when they have the advantage of a good sailing breeze and smooth water. The angle of the lee-way, however, enlarges in proportion to the increase of the wind and sea. In this dis- position of the sails they are all extended sideways on the ship, so that the wind, as it crosses the ship obliquely towards the stern from forwards, may fill their cavities. But as the current of wind also unites the cavities of the sails in an oblique direc- tion, the effort of it, to make the ship advance, is considerably diminished: she will, therefore, make the least progress when sailing in this manner. The ship is said to be close-hauled, ‘C O A C O C 175 DICTIONARY OF MECHANICAL SCIENCE, because at this time her tacks, or lower corners of the princi- pal sails, are drawn close down to her side to windward; the sheets hauled close aft; and all the bowlines drawn to their greatest extension, in order to keep the sails ready. CLOSE QUARTERS, certain strong barriers of wood stretching across a merchant ship, in several places; they are used as a place of retreat when a ship is boarded by her adver- sary, and are therefore fitted with loop-holes through which to fire the small arms; they are likewise furnished with caissons, or powder-chests, fixed upon the deck, which may be fired at any time from the close quarters upon the boarders. An English merchant ship of 16 guns, by being properly fitted with close quarters, has been known to defeat the united efforts of three French privateers who boarded her, after having engaged at some distance nearly a day and a half, with very few inter- vals of rest. Two of the cruisers were equipped with 12 guns each, and the other with 8. The French sailors were, after boarding, so much exposed to the continued fire of musketry, and cohorns charged with grenadoes, that a dreadful scene of carnage ensued, in which the decks were soon covered with the dead bodies of the enemy, several of which the boarders, in their hurry to escape, had left behind. CLOUD, a visible aggregate of minute drops of water sus- pended in the atmosphere. The same aggregate, which in this situation is called a cloud, obtains the name of mist, when seen to arise from the earth or waters; and fog, when it envelopes and covers the observer. Yet the two latter, viewed from a greater distance or elevation, present all the appearances of clouds; while those, in their turn, become mists and fogs, in proportion as we approach and penetrate them. It is con- cluded, from numerous observations, that the particles of which a cloud consists, are always more or less electrified ; and this fluid has hence been considered as the cause of the formation of all clouds whatever, whether of thunder, hail, rain, or snow. See Meteo R. The hypothesis which assumes the existence of vesicular vapour, and makes the particles of clouds to be hollow spheres, which unite and descend in rain when ruptured, however sanc- tioned by the authority of several eminent philosophers, does not seem necessary to the science of meteorology in its present state; it being evident that the buoyancy of the particles is not more perfect than it ought to be, if we regard them as mere drops of water. In fact, they always descend, and the water is elevated again only by being converted into invisible Waſ) Our. - . The height of the clouds is supposed to be from about a quarter of a mile to a mile. It is common for persons by climbing very high mountains, to get above the clouds, and see them swim beneath them. The wonderful variety in the colour of the clouds is owing to their particular situation with regard to the sun, and the different reflections of his light. The dif. ferent figures of the clouds result from their loose and voluble texture, revolving into any form according to the varied force of the winds. Those small clouds, sometimes seen very high, and heaped upon one another, presage rain very soon. When the horizon, at the rising or setting of the sun, appears pale and yellowish, it is a sign of the air being full of vapours, and threatens bad weather. But when it is of a light red at those times, there are but few vapours in the air, and fine weather may be expected. The quantity of vapour evaporated at any degree of heat or wind, depends on the quantity of vapour already in the atmosphere. --> COAL, a solid inflammable substance commonly used for fuel. There are various species, 1. Pit Coal, is a black, com- pact, brittle mass, which, according to Kirwan, consists of petrol or asphaltum mixed with argillaceous earth; seldom with calcareous; and frequently also with pyrites. 2. Culm Coal, this has a greater portion of argillaceous earth and vitriolic acid, with a moderate portion of petrol. It burns with a flame without being consumed. 3. Slate Coal, contains so much earth, that it looks like common slate ; but burns with a flame. There are large quarries of it at Purbeck, in Dorsetshire. 4. Cannel Coal, or ampelites, is of a dull black colour, and burns with a bright flame, but is apt to fly to pieces in the fire. This kind is used for making various toys, which appear like jet. 5. Kilkenny Caal, is the lightest of all, and contains the largest hemiptera. quantity of asphaltum ; burns with less smoke and flame, and more intensely, though more slowly, than cannel coal. 6 Sul- phurous Coal, has a considerable portion of pyrites, whence it is apt to moulder and break when exposed to the air, after which water will act upon it. There are in it yellow spots resembling metal. , 7. Bovey Coal, is of a dark brown colour, and of a yellow lamina and texture. The laminae are flexible when first dug, but harden when exposed to the air. It con- sists of wood penetrated with petrol or bitumen, and frequently contains pyrites, alum, &c. 8. Jet. This substance is found in France, Spain, Germany, Britain, and other countries. It is found in detached kidney-formed masses of various sizes, and is of a very deep glossy black colour, opaque and hard. CoAL, Small, a sort of charcoal prepared from the spray and brush-wood stripped off from the branches of coppice wood, sometimes formed in bavins for that purpose, and sometimes charred without binding. It is used by artificers to temper and anneal their works. COAL GAS, is of the highest importance, from the beautiful light which it yields. When coals are burning on the fire, we see the stream shooting out, and inflaming when a light is held near it: this is coal gas. To obtain gas, the coals are enclosed in iron retorts, which are heated red-hot; the coal is literally dissolved, and the gas rising up in the retort, is made to pass through water and other substances, to free it from impurities. It is collected in a gasometer, from which it is transmitted by pipes to whatever distance it may be required, with the same facility as if it were water from a reservoir; indeed, with greater ease, as the level of a reservoir of water must always be higher than the place to which water is con- ducted ; but from the buoyancy and lightness of gas, it will ascend to any height to which it may be desirable to con- duct it. The gas produced from coal is chiefly the carbu- retted hydrogen gas, which consists of carbon and hydrogen, chemically combined. This is, however, by no means in a state of purity, but is only the predominant gas in the mixture. COASTING, is that part of navigation which is carried on near the coast or shore, without losing sight of land, except occasionally for a short period. COAT of ARMs, in Heraldry, was a habit worn by the ancient knights, over their armour, reaching as low as their navel. The term is used for the bearing of a person or family. COATING, the application of clay or some other substance about a glass vessel, to keep it from breaking by the violence of the fire. COBALT, in Chemistry, a metal, when pure, of a white colour, inclining to bluish or steel gray. At the common tem- perature its specific gravity is more than 8.5. It is attracted by the magnetic needle, and is itself capable of polarity. For fusion, it requires nearly the same intensity of heat as cast iron. Cobalt occurs in nature alloyed with other metals, and mine- ralized by oxygen, and by arsenic acid. The white cobalt ore is an alloy of cobalt and arsenic, with a little sulphur, and in some specimens a little iron, the two latter being probably accidental. The gray cobalt ore, as it has been named, is an alloy of cobalt with arsenic and iron ; sometimes, also, as has been affirmed, with small portions of nickel and bismuth. Cobalt combines with many of the metals. Its alloys are generally brittle, and none of them have been applied to any use; nor have they been much examined. The principal, or indeed almost the sole use of cobalt, is in communicating a blue colour to glass, enamel, and porcelain. Smalt and azure blue are merely cobaltic glass in fine powder. Zaffre is a flint powder, and an impure oxide of cobalt prepared by calcination of the ores. - COBITIS, the Loache, a genus of fishes, of the order of abdominales, of which there are five species, natives of the rivers in Europe. The loache generally keeps at the bottom on the gravel, whence it is called the groundling. . COBOOSE, the place where the victuals are cooked on board merchant ships. COCCULUS INDICUS, a poisonous berry, too frequently mixed with malt liquors to make them intoxicating. It is the fruit of the monospermum cocculus. COCCUS, a genus of insects belonging to the order of The coccus cacti, a native of the warmer paiºs of 176. :C O D O O. G. DICTIONARY OF MECHANICAL SCIENCE. America, is the famous cochineal animal. The female, which alone is valuable for its colour, is slothful and ill-shaped. The male is scarce, and sufficient for three hundred females. It is small, slender, and active. The cochineal insect resembles the silkworm in the manner of depositing its eggs. The insects destined for this purpose are taken and put into a box lined with a coarse cloth, where they lay their eggs, and then die. The box is kept close shut till the time of placing the egg on the foliage of the cactus cochenilifer or Indian fig, called by the Spaniards nopal. At Oaxaca, in Mexico, the cochineal insects are gathered in large quantities, and the cultivation of them is the employment of the Indians. In trade there are ſour sorts of cochineal-mastique, campeschane, tetraschale, and Sylvester. The first is the best, and the last the worst. The cochineal is esteemed in medicine as a cordial, sudorific, and febrifuge; but it is chiefly used by dyers and painters. Coccus lacca, or gum lac animal, is a native of the East Indies. This species fix themselves upon the succulent extremities of the young branches of the trees they inhabit, and are as it were glued thereto by a red liquid, which gradually accumulating, forms a complete cell, and is what is called gum lac. Out of this pro- ceed the young insects, leaving the exuviae behind, which is that white membranous substance found in the cells of the stick lac. The gum lac brought to this country is principally found on the mountains on both sides the Ganges, and is of a deep red colour. Coccus Polonicus, or the scarlet grain of Poland, is usually met with at the root of the plant called polygonum cocciferum. COCHINEAL, was at first supposed to be a grain, which name it still retains by way of eminence among dyers, but naturalists soon discovered that it was an insect, a species of the coccus. Fine cochineal, which has been well dried and properly kept, ought to be of a gray colour inclining to purple. The gray is owing to a powder which covers it naturally, a part of which it still retains : the purple tinge proceeds from the colour extracted by the water in which it has been killed. Cochineal will keep a long time in a dry place. Hellot says, that he tried some 130 years old, and found it to produce the same effect as new. COCHLEA, the same as screw ; being thus called in conse- quence of its resemblance to the spiral shell of a snail, called by the Latins cochlea. COCKBOAT, a small boat used on rivers near the shore. In ancient days a cock was the general name of a yawl. COCKPIT, in a ship, is near the apartments of the surgeon and his mates, being the place where the wounded men are dressed. It is situated near the after hatchway, and under the lower gun-deck. Fore Cockpit, a place leading to the magazine passage, and the boatswain's, gunner's, and carpenter’s store rooms; in large ships, and during war time, the boatswain and carpenter generally have their cabins in the fore cockpit, instead of being under the forecastle. COCOS, in Botany, a genus belonging to the natural order of palmae, and of the monoecia hexandria class. There are five species. The principal is, cocos nucifera, or cocoa-nut tree. It frequently grows to the height of sixty feet, and is smaller in the middle than at top and bottom. Owing to the load of nuts which it bears, it leans to one side. The colour is of a pale brown, and the bark smooth. The leaves are often fourteen or fifteen fect long, and about twenty-eight in num- ber. The nuts hang at the top of the trunk in clusters of a dozen each. The nut has, next the stem, three holes closely stopped. When the kernel begins to grow, it incrusts the inside with a substance like jelly; this hardens and increases till it becomes white. The quantity of liquor in a full-grown nut is about a pint, and is pleasant to the taste. The husky tegu- ment of the nut consists of tough, stringy filaments, like coarse oakum. The leaves are made into brooms, mats, sacks, and other useful articles. CODE, a collection of the laws and constitutions of the Roman emperors, made by order of Justinian. CODEX, a book or tablet, used by the ancients. CODIC [L, a writing, added by way of supplement when a thing has been omitted, that the testator wishes to appear in his-lèst will. CO-EFFICIENTS, in Algebra, are numbers or letters pre- fixed to other letters, or unknown quantities, into which they are supposed to be multiplied ; and, therefore, with such letters, or the quantities represented by them, making a product, or co-efficient product. See ALG ebRA. - - COFFEA, or the Coffee TREE, a genus of the monogynia order, in the pentandria class of plants, ranking in the natural method under the 47th order stellatae. There are 10 species, the principal of which is a native of Arabia Felix, which rises about 16 or 18 feet in height: the main stem growing upright, is covered with a light brown bark; the branches are produced horizontally and opposite, crossing each other at every joint. The leaves also stand opposite, and when full grown, are about four or five inches long. and two broad in the middle, decreas- ing towards each end: the bodies are waved, and the surface is of a lucid green. The flowers, which are white, are produced in clusters at the root of the leaves, sitting close to the branches. The fruit resembles a cherry. It grows in clusters along the branches, under the axillae of the leaves. It is at first of a green colour, and when of a deep red, is gathered for use. The coſſee tree is cultivated in Arabia, Persia, the East Indies, and America. It is also raised in botanic gardens, in several parts of Europe. Coffee is said to assist digestion, and is good in relieving the headache; and for very weak constitu- tions, should be drank immediately after dinner. It is taken in large quantities by the Turks and Arabs. • . COFFER, in Fortification, is a hollow lodgment across a dry moat, on which are raised pieces of timber, and hurdles filled with earth, serving as a parapet with embrasures. The use is for the besieged to defend the ditch, and to repulse the besiegers. - - COFFER DAM, a term applied by engineers to denote the enclosures formed for laying the foundation of piers and other works in water, to exclude the surrounding fluid, and thus forming a protection both to the work and workmen. COGNATION, in Civil Law, a term for that line of consan- guinity between males and females, both descended from one father. . - COGNISOR, in Law, one that passeth or acknowledgeth a fine of lands or tenements to another. - COGNOVIT Action eM, in Law, is an acknowledgment by a defendant, or confession, that the plaintiff's cause of action is just, and therefore suffers judgment to go against him. COG WHEEL. Wheels acting upon each other are the in- struments by which the transmission of mechanic force from one part of a system of machinery to another is commonly and con- veniently effected. The due connexion of the moving parts is accomplished either by the mutual action of properly formed teeth, in some instances called Cogs, by straps or endless bands, or, by the friction of one face of a wheel against another. Among the ingenious inventions of the present day, for the communication of motion in machines, in lieu of the ordinary cog or toothed wheels, the invention of Lewis Gompertz, Esq. of the Kennington Oval, Surry, is so perfectly original as to require the most extensive publicity. The following is its de- scription in the words of the inventor's specification of the patent which he obtained for this improvement in the arts, dated April 27th, 1814. “One of the wheels I call the pin wheel, because it is provid- ed with pins, marked B C D E, see Plate, figs. 1, 2, and 5, which pins may be furnished with friction rollers, and which project perpendicularly from its plane, and communicate motion to the other wheel, called the curve wheel, (or vice versa,) by entering curved grooves G H I K, made in the surface of it, as shewn in the perspective view, fig. 5. The axes, and consequently the planes of the two wheels, are so inclined to each other, that the ends of the pins B C are beneath the surface of the curve wheel, and therefore enter into the grooves. But, in conse- quence of the inclination of the wheels as the pins approach the point D, or come té the line between the centre of the wheels, their ends come to the surface of the wheel, so as to leave the grooves; and as they proceed towards E, they are so completely above the wheel as to pass over without touching it. The manner of action is this: the pin C is engaged in the groove G, and the pin B is on the point of entering H; by the revolution of the pin wheel its pins B and C act in the grooves, | | | | . - * (ſº | | º N ºn tº | | | | | | | º : | -in- | º | ( \º N. . - | | º * * * º - - | - - | | || º - \ - º | | - º |5. N U. º - º º | Sº - | º - | | º -- - - º s o og G O H 177 DICTIONARY OF MECHANICAL SCIENCE. and pressing in their curves, turn the curve wheel round upon its centre; and as the pins in succession quit the grooves in the same manner as the pin D is supposed to have quitted the groove K, the other pins very soon after enter the next groove but one, in the same manner as B is entering into H, and by this means, before any pin leaves its groove, the succeeding pin has just entered, and a constant action of the pins in the groove is kept up. The law of the action depends upon the nature of the curves, which may be varied at pleasure, so that they will turn each other with an equal velocity, and with a perfect regular motion; or by an irregular one, or the curves may be made to turn with twice or three times the velocity, or in almost any ratio required, also to turn each other in either direction; thus, in figs. 1 and 5, both the wheels turn round in the same direction as shewn by the arrows, but in fig. 2 the grooves are differently curved, and they turn contrary ways to each other. A manner of finding the curves for these grooves is explained in fig. 4. First describe the circle F l, for the size of the curve wheel; then draw a circle, A B C D, for the pin wheel, and divide it into the number of pins it is intended to have, for example twelve; subdivide the spaces between each of the pins D C and C B into any number, eight for ex- ample, and figure the divisions, as shewn next; on the centre F draw a circle through each of the said divisions, also a circle A R T passing through the centre of the pin wheel. Now, divide the circumference of this circle into as many parts as the wheel is to have curves, this will depend upon the ratio the velocities of the wheels are to bear to each other; thus, if it is to turn twice for once of the pin wheel, there must be half as many curves as there are pins; therefore in the drawing, the circle A R T is to be divided into 6, and each sixth is sub- divided into as many equal parts as the spaces C and D were. viz. eight. These spaces are to be numbered as shewn. With this preparation proceed to set out the curves, by taking the radius A D in the compasses, and setting one point in the divi- sion marked 3, between T and A ; make a mark at , upon the external circle, also numbered 3, towards that side where the curve wheel is to be elevated, (by side, is not meant side of the wheel, but side of the position of the wheel, or of absolute space, as the wheel changes in turning, and what is high in one instance is low in the next,) because it passes through the divi- sion 3, between B and C. This mark will be the first point of one of the curves. Then, from the division 4, mark the circle 4 for the second point; next from the point 5 to the circle 5; and so on through the whole number of circles. This will find a number of points, forming a curve G C ar, which will be the centre line of the intended groove. And to find its breadth, describe small circles round each of these points, rather larger than the pins, as drawn. The edges of the grooves may then be drawn as tangents to these circles. The succeeding curves H and I are found in exactly the same manner from the suc- ceeding divisions on the great circle, beginning on the division 3, between A R, and so on all round. On the opposite side of the circle are shewn curves g h i, proper for giving the curve wheel an equal velocity with the pin wheel, and there will therefore be twelve of these curves in the whole. The prepa- ration is exactly the same, but the great circle instead of six is divided into twelve, as at the points a 7" and t, and each of these are subdivided into eight (or the same number as between d and C;) then the curves are set out from these points exactly as before: in both these cases the wheels are considered as revolving in the same direction, as shewn by the arrows figs... 1 and 5. If it is required that they should turn each other in opposite directions, the curves must be reversed, as shewn in fig. 2. To set out these curves, the same lines and divisions as in fig. 4 are used; but the division between T A and A. R. must be figured the contrary way, namely, beginning at R and proceeding to A; then 'setting one foot of the compasses at 5, between A and R, and the other leg in the first circle (marked 3) towards that side where it is meant to be elevated, and as one leg is moved towards T, move the other leg towards the centre; and for the next curve begin with the next same num- ber towards T, and so on, and mark as before. A reverse curve will here be produced, as shewn dotted at l C m, and a wheel, constructed with these curves, as in fig. 2, will turn in a contrary direction to the pin wheel, as shewn by the arrows. “Fig. 3 represents a curve wheel, with six curves, which therefore revolve twice for once of the pin wheel; but the curves are so arranged, that for two-thirds of its revolution the curve wheel revolves at the rate of four to one of the pin wheel, viz. while the pins are acting in the curves G and K, the four re- maining, curves I L M H are close together, and the action of the pins, when in them, only advances the curve wheel double the space of the pin wheel; but the motion of the curve wheel, even while the pins are acting in these grooves, may be made irregular, to almost any required law; thus, at the external parts I L M, where the pins first enter, the grooves are curved the same as ſig. 2, and therefore the pins will in these positions turn the curve wheel twice as fast as they move themselves, but on entering and moving through the returned parts i ! m of the curves, the pin communicates a recoiling motion to the curve wheel, which continues till the pin enters the last por- tions t w w, and at the same time a succeeding pin enters the next curve; this again actuates the curve wheel, as in the first instance. - “This wheel is set out on the same principle as the others, see fig. 6, which is prepared exactly as before, except the divid- ing of the great circle, which must in all cases be done accord- ing to the motion the curve wheel is intended to have given to it; in the present instance it is first divided in 3, at A R S, and each of these subdivided into eight; then from No. 3, between R and A, mark on the outside circle 3; from 4 to the circle 4; and so on till the curve G is brought as far as the next circle marked 3, from which place only move the leg in the large cir- cle half a division; then set out K, by following the same pro- cess on another part of the great circle, excepting that the leg in the large circle is continually to be moved a whole division. To obtain the four other curves, take the space from ſig. 3 m to 3 q, which is one-third of the whole circle, and divide it into four, viz. at m n o p q ; then each of these spaces being sub- divided into four, as shewn by the figures 40, 50, and 60, pro- duce the curves thus: begin at m, and mark on the external cir- cle for the first division of H, then from 40 mark on the circle 4, and continuing this till six circles, towards the centre, are marked, and the curve H is finished; this will have brought the compasses to one division beyond n; for the returned part h mark the two next circles towards the centre, and by return- ing one division for each in the large circle, this brings the compasses back to 60, and advancing from that point, begin the interior part w, and also the part M of the next curve, which is completed by a repetition of the same process on the suc- ceeding part of the circle, as is likewise L and I i ; but the in- terior end a of the latter must be set out from the great divi- sions of the circle R. S.; thus, when the part i is ended from 69 next to q 3, advance the compasses to the points 4, 5, 6, and 7, for marking the successive circles till the curve is completed. “This is given only as an example of the manner of making a wheel to turn with any required degree of irregularity in its motion; but I claim all varieties of curves which may be made to act on the principles I have described, to communicate re- gular or irregular motion from the pins of a wheel.” ſ: COHESION, that species of attraction, which, uniting par- ticle to particle, retains together the component parts of the same mass; being thus distinguished from adhesion, or that species of attraction which takes place between the surfaces of similar or dissimilar bodies. Whatever may be the cause of cohesion, its effects are evident and certain, and the different degrees of it is what constitute bodies of different forms and properties; at least, this is the opinion of Sir Isaac Newton, and other eminent philosophers. - Various experiments have been made by different authors, to ascertain the power of cohesion, in bodies of different textures; as woods, metals, glass, &c. These experiments have generally been made on cylindric bars, an inch, or certain parts of an inch, in diameter; and as it has been proved, that the direct cohesive strength of a body is in the joint ratio of its primitive elasticity, toughness, and area of its section, it follows, that having ascertained the cohesive power with any given section, the same may be found for the same substance for any other section, and thus the experiments of different authors oom- pared with each other. . . . . . . . . , 2 Z 178 c o L C O I Diction ARY of MECHANICAL scIENCE. The following table shews the weights which were necessary to tear asunder rods of different substances, whose bases were each a square inch, the weights being applied in the direction of their length. lbs. Avoirdupois. METALS, lbs. Avoirdupois. WOODS. Steel, ..... . . . . . . . . . . . 135000 || Beech, oak, ........... 17300 Iron bar, . . . . . . . . . . . . . 74000 || Alder, . . . . . . . . . . . . . . . 13900 Cast iron, . . . . . . . . ... .. 50100 | Elm, . . . . . . . . . . . . . . . . 13200 Copper, east, ... . . . . . . 28600 || Mulberry, ............ 12500 Silver, ditto, . . . . . . . . . 41500 | Willow, .............. 12500 Gold, ditto, . . . . . . . . . 22000 | Ash, . . . . . . . . . . . . . . . . 12000 Tin, ditto, ......... 4000 || Plum, . . . . . . . . . . . . . . . . 11800 Bismuth, . . . . . . ... . . . . 2900 | Elder, . . . . . . . . . . . . . . . 10000 , Zinc, . . . . . . . . . . . . . . . . 2600 | Fir, . . . . . . . . . . . . . . . . . 8330 * Antimony, . . . . . . . . . . . 1000 || Pitch, pine, . . . . . . . . . . 7656 ! Lead, cast, . . . . . . . . . . 860 | Cypress, ... . . . . . . . . . . . 6000 • , | Poplar,. . . . . . . . . . . . . . 5500 Cedar, . . . . . . . . . . . . . . 4.880 Other experiments have been made to ascertain the strength of cobesion in bodies, when placed horizontally, and loaded with weights in different parts; but as we shall have occasion to return to this subject under the article STRENGTH of Mate- rials, we shall, in this place, merely state the result of Muschen- broek's experiments on a few of the most common woods. For this purpose he fixed pieces of wood, by one end, into a square hole in a metal plate, and hung weights towards the other end, till they broke at the hole. The weights, and their distances from the point of support, are shewn in the following table :-- , WOODS. Dist. in Inches. Weight in oz. Pine, . . . . . . . . . . . . . . . . . . 9} . . . . . . . . . . . . . . . . . . 36% Fir, . . . . . . . . . . . . . . . . . . . . 9 . . . . . . . . . . . . . . . . . . 40 Beech, . . . . . . . . . . . . . . . . 7 . . . . . . . . . . . . . . . . . . 56; Blm, . . . . . . . . . . . . . . . . . . 9 . . . . . . . . . . . . . . . . . . 44 Oak, . . . . . . . . . . . . . . . . . . 8} . . . . . . . . . . . . . . . . . . 4S Elder,. . . . . . . . . . . . . . . . . . 9+ . . . . . . . . . . . . . . . . . . 48 In the above table the rods were rectangular parallelopipe- dons, and the side of their square section 26 of an inch. Coulomb found the lateral cohesion of brick and stone only ºr more than the direct cohesion ; which, for stone, was 215 lb. for a square inch; for good brick, from 280 to 300. Count Rumford found the cohesive strength of a cylinder of iron, an inch in diameter, 63466, or 63173 lb. ; the mean, 633.20; which is only 3, more than Emerson's result. Sickingen makes the comparative cohesive strength of gold, 150955; of silver, 190771; of platina, 262361; of copper, 304696; of soft iron, 362927; of hard iron, 55.9880. Guyton makes platina a little stronger. ſ COILING, is a sort of serpentine winding the ropes, by which they occupy a small space, and are not liable to be entangled amongst one another in working the sails. Each winding of this sort in a cable is called a fake, and one range of fakes is called a tier; there are generally from five to seven fakes in a tier, and three or four tiers in a cable's length : the small ropes are frequently coiled by hand, and hung upon cleats to prevent their being entangled amongst one another, in traversing, contracting, or extending the sails. COINING, the art of making money, is performed either by the hammer, or the mill and steam-engine. By either of these methods the pieces of metal are stamped or struck with punches or dies, on which are engraven the sovereign, effigies, arms, legend, &c. The puncheon consists of a highly tempered piece of steel, upon which the coin is sunk in relievo, and again upon the matrix, which is another piece of steel some four inches long, formed square at the bottom, and rounded at . its top. The moulding of the border and letters is added on the matrix with small and sharp steel puncheons, and when it is thus finished, it is called the die. In coining with the mill, the bars or plates of gold or silver, after having been moulded, and taken out of the mould, are scraped and brushed, and passed several times through the mill to flatten them, and bring them to the just thickness of the specie to be coined. But the plates of gold are heated again, and quenched in water before they pass through the mill, which renders them more ductile : those of silver pass the mill just as they are, without any heating; and when afterwards heated, they are left to cool, The plates thus reduced as nearly as possible to their thick- ness, are cut into round pieces the size of the intended specie. The cutting instrument has its upper end formed into a screw ; which being turned by an iron handle, lets the steel, well sharpened, in form of a punch-cutter, fall on the plates; and thus a piece is punched out. These pieces are now adjusted, and brought, by filing or rasping, to the weight of the regulated standard; what remains of the plate between the circles is melted again. The pieces are adjusted in a fine balance; and those too light are separated from those which are too heavy; the first to be again melted, and the second to be filed down. The mill through which the plates pass can never be so just but there will be some inequality. - The pieces are called blanks, and are carried to the blanching or whitening-house, where the gold pieces have their colour given them, and the silver ones are whitened. This is done by heating them in a furnace, and when taken out and cooled, boiling them successively in two copper vessels, with water, common salt, and tartar, and after that scouring them well with sand, and washing them with common water, drying them over a wood fire, in a copper sieve, into which they are put when taken out of the boilers. In England, the standard for gold is eleven parts of pure metal and one of alloy; for silver, 11 oz. 2 dwts. of pure silver, and 18 dwt.s. alloy, making together 1 lb. troy weight. * In the machinery invented for coining, by the late Messrs. Boulton and Watt, and lately introduced into the Royal Mint, London, the screw presses for cutting out the circular pieces of metal, are worked with great facility, and both the edges and the faces of the money are coined at the same time, with such superior excellence, and cheapness of workmanship, as will prevent clandestine imitation, except in a very limited degree indeed. By means of this machinery, four boys can strike 30,000 pieces of money in an hour: the machine acting at the same time as a register in keeping an unerring account of the number of pieces that have been struck 1 ... - COKE, a preparation of fossil coal, whereby it is deprived of the naptha, bitumen, or asphaltum, it may contain, so that when applied to certain purposes, it may not communicate a bad flavour or bad qualities. Coke is made in very large ovens, principally from the refuse of brush-coal, with which some pits abound; the coal in them being extremely brittle, and rarely coming away in large pieces. In great towns which are lighted with gas, coke is obtained in great abundance from the gas-works, being left in the retorts after the gas is driven off by the heat. - COLD, in common language, denotes the sensation which is felt, or the effect which is produced, by the abstraction of heat; that is, heat and cold are opposite to each other, and the existence or increment of the one, is equal to the want or decre- ment of the other; so that the same degree of temperature may be called hot or cold, according as it is compared with a colder or hotter temperature. Thus the climate of Great Bri- tain is a cold climate, in comparison with that of the West India islands; and a hot climate, in comparison with that of Siberia. If a man warms one of his hands near a fire, whilst he cools his other hand by means of ice ; and if afterwards he plunges both his hands in a basin of water of the common temperature of the atmosphere, that water will feel cold to the hand that has been heated, and hot to the other hand. From this it appears, that cold is not any thing real, but merely a privation of heat; so that instead of saying, that a body has been cooled to a certain degree, it may with equal truth and propriety be said, that the body has been deprived of heat to that certain degree. See FREEZING.; : ... Notwithstanding the simplicity of this theory, and the con- viction which seems to accompany it, philosophers have often entertained doubts concerning it; and they have endeavoured to inquire into the real state of the matter, by devising experi- ments capable of demonstrating whether the cause of heat was any thing real, and that of cold only a privation or diminution of the former; or, vice versa, whether the cause of cold was any thing real, and that of heat a diminution ; or, lastly, whether the production of heat, and the production of cold, were not owing to two distinct principles or elements. * On the supposi- C, O L. C O L. DICTIONARY OF MECHANICAL SCIENCE. 179 tion that the cause of one of those effects only is real, it is much more natural to suppose, that the cause of heat is the real prin- ciple or element; since its effects, viz. enlargement of the bulk of bodies, the separation of their parts, &c. are such as must be produced by the introduction of something real; and the abstraction of this principle may naturally produce the effects of cold, such as contraction of the bulk of bodies, agglutination, &c.; whereas it would be unnatural to suppose, that a body contracts its bulk, as its parts come into closer contact, because something else has been introduced amongst them. With respect to the last supposition, viz. whether the effects of heat and those of cold be not owing to two distinct principles, a few arguments, and the equivocal result of a few experiments, have, at times, been adduced in support of it. But the general and prevailing opinion among the philosophers is, that a single element, called caloric, produces heat, or the effects of expand- ing bodies separating their parts, &c.; and that cold is only a relative expression ; that is, meaning only the decrement of heat; so that real or absolute cold consists only in the total abstraction of caloric ; and, that such a point, viz. the zero of heat, may be determined, has been shewn by the experiments, the discoveries, and the calculations of Irvine, Black, Craw- ford, and others; but it is impossible, in this place, to enter into an investigation of the methods made use of in deter- mining this remarkable point. See ICE. - COLEOPTERA, the beetle tribe of insects, comprehending all those with four wings, the external pair of which are hard, rigid, and opaque, forming a kind of covering for the inner. There are 56 genera of this order. COLIC, a severe pain in the lower venter, so called because the disorder was thought formerly to be in the colon. There are different kinds, as the windy colic, the bilious, the hysteric, the nervous, and the Devonshire colic. - COLLAR, an ornament consisting of a chain of gold, with devices, and ciphers, worn by the knights of the different orders. Collar of a ship, is a rope fastened about the beak- head, into which the dead-man's eye is seized that holds the main-stay; also the rope wound about the head of the main- maSt. w COLLATERAL, those relations which proceed from the same stock, but not in the same ascending or descending line. COLLATION, is the giving or bestowing of a benefice on a clergyman by the bishop, who is the patron thereof. COLLIMATION, LINE of, on a telescope, is a line passing through the intersection of those wires that are fixed in the focus, and the centre of the object-glass. COLLISION, in Mechanics and Physics, is the meeting and mutual striking of two or more bodies, one of which, at least, is in motion. The most simple of the problems relating to collision was that of a body proceeding to strike against another at rest, or moving before it with less velocity, or approaching towards it. In the mutual percussion of several bodies, the absolute quantity of motion of the centre of gravity is the same after as before the shock. Farther, when the bodies are elastic, the relative velocity is the same after as before percussion. All this, however, is upon the supposition, that bodies are either perfectly hard, or perfectly elastic ; but as there do not exist in nature any bodies which we know of, either the one or the other of these kinds, the usual theories are of little or no service in practical mathematics. COLLYRIUM, a topical remedy for inflammations of the eyes. The best is a small portion of brandy and spring water. COLONNADE, in Architecture, a peristyle of a circular figure, or a series of columns disposed in a circle, and insulated withinside. - COLOUR, in Natural Philosophy, is that property of bodies which affects the sight only; or that property possessed by the elementary rays of light, separated by any means whatever, of exciting in us different sensations according to their different refrangibility. Thus colour may be considered in two respects, as it regards bodies in general, and as it is produced by solar light. See Optics. Before the time of Newton, the ideas of mankind concerning colour were very vague and unsatisfactory. The Pythagoreans called colour the superficies of bodies: Plato said that it was | which configuration of matter: and Aristotle said it was that made bodies actually transparent, Dr. Hooke imagined, that colour is caused by the sensation of the oblique or uneven pulses of light; which being capable of no more than two varieties, he concluded there could be no more than two primary colours. It was also an opinion, that the solar light was simple and uniform, without any difference or variety in its parts, and that the different colours of objects were made by refraction, reflection, or shadows. But Newton taught them the errors of their former opinions; he taught them to dissect a single ray of light with the minutest precision, and demonstrated that every ray was itself a composition of several rays all of different colours, each of which when separate held to its own nature, simple and unchanged by every experiment that could be tried upon it. Or, to be more particular, light is not all similar and homogeneal, but compounded of hetero- geneal and dissimilar rays, some of which, in like instances, being more refrangible, and others less refrangible, and those which are most refrangible are also most reflexible ; and according as they differ in refrangibility and reflexibility, they are endowed with the power of exciting in us sensations of different colours. . - Newton's theory of light and colours is striking and beautiful in itself, and deduced from clear and decisive experiments. 1st. That lights which diſſer in colour, differ also in degrees of refrangibility. 2d. That the light of the sun, notwithstanding its uniform appearance, consists of rays differently refrangible. 3d. That those rays which are more refrangible than others, are also more reflexible. 4th. That as the rays of light differ in degrees of refrangibility and reflexibility, so they also differ in their disposition to exhibit this or that particular colour; and that colours are not qualifications of light derived from refractions or reflections of natural bodies, as was generally believed, but original and connate properties, which are different in different rays, some rays being disposed to exhibit a red colour and no other, and some a green and no other, and so of the rest of the prismatic colours. 5th. That the light of the sun consists of violet-making, indigo-making, blue-making, green-making, yellow-making, orange-making, and red-making rays; and all of these are different in their degrees of refram- gibility and reflexibility; for the rays which produce red colours are the least refrangible, and those that make the violet the most ; and the rest are more or less refrangible as they approach either of these extremes, in the order already men- tioned; that is, orange is least refrangible next to red, yellow next to orange, and so on; so that to the same degree of refram- gibility there ever belongs the same colour, and to the same colour the same degree of refrangibility. 6th. Every homoge- neal ray, considered apart, is refracted according to one and the same rule, so that its sine of incidence is to its sine of refraction in a given ratio; that is, every different coloured ray has a different ratio belonging to it. 7th. The species of colour, and degree of refrangibility and reflexibility, proper to any particular sort of rays, is not mutable by reflection or refrac- tion from natural bodies, nor by any other cause that has been yet observed. When any one kind of rays has been separated from those of other kinds, it has obstinately retained its colours, notwithstanding all endeavours to bring about a change. 8th. Yet seeming transmutations of colours may be made, where there is any mixture of divers sorts of rays; for, in such mix- tures, the component colours appear not, but, by their mutually alloying each other, constitute an intermediate colour. 9th. There are therefore two sorts of colour, the one original and simple, the other compounded of these ; and all the colours in the uni- verse are either the colours of homogeneal, simple light, or compounded of these mixed together in certain proportions The colours of simple light are, as we observed before, violet, indigo, blue, green, yellow, orange, and red, together with an indefinite variety of intermediate gradations. The colours of compounded light are differently compounded of these simple rays, mixed in various proportions: thus a mixture of yellow- | making and blue-making rays exhibits a green colour, and a mixture of red and yellow makes an orange; and in any colour the same in specie with the primary ones, may be produced by the composition of the two colours next adjacent in the series a flame issuing from them : according to Zeno, it was the first of colours gencrated by the prism, whereof the one is nex” 180 C O L ‘C o L DICTIONARY OF MECHANICAL SCIENCE. . more refrangible, and the other next less refrangible. But this is not the case with those which are situated at too great a distance; orange and indigo do not produce the intermediate green, nor scarlet and green the intermediate yellow. 10th. The most surprising and wonderful composition of light is that of whiteness; there is no one sort of rays which can alone exhibit that colour; it is ever compounded, and to its composi- tion all the aforesaid primary colours are requisite. 11th. As whiteness is produced by a copious reflection of rays of all sorts of colours, when there is a due proportion in the mixture, so, on the contrary, blackness is produced by a suffocation and absorption of the incident light, which being stopped and sup- pressed in the black body, is not reflected outward, but reflected and refracted within the body till it be stifled and lost. - - This method of accounting for the different colours of bodies, from their reflecting this or that kind of rays most copiously, is so easy and natural, that his system quickly overcame all objections, and to this day continues to be almost universally believed. It is now commonly acknowledged, that the light of the sun, which to us seems perfectly homogeneal and white, is composed of no fewer than seven different colours, viz. red, orange, yellow, green, blue, purple, and violet or indigo. A body which appears of a red colour, has the property of reflecting the red rays more powerfully than any of the others; and so of the orange, yellow, green, &c. A body which is of a black colour, instead of reflecting, absorbs all, or the greatest part of the rays that fall upon it; and, on the contrary, a body which appears white, reſlects the greatest part of the rays indiscriminately, without separating the one from the other. Colours used in Drawing and Painting.—Red Colours are: Lakes. This term denotes those colours which are formed by the combination of alumine, or the oxide of tin, with the colour- ing matters of vegetables. The lakes chiefly used are red colours, of different qualities, according to the basis and colouring matter employed; and are known by the names of Carmine, Florence-lake, and Madder-lake. Carmine, a very rich bright crimson colour, stands well in water. For the preparation of carmine, take four ounces of finely-pulverized cochineal, which pour into four quarts of rain or distilled water, boiled previously in a pewter kettle, and boil the whole for six minutes; add, during the boiling, two drachms of pulverized crystals of tartar. Eight scruples of Roman alum, in powder, must be then added, and the whole be kept on the fire one minute longer. As soon as the gross powder has subsided, and the decoction become clear, decant it into large cylindrical glasses covered over, and kept undisturbed till a fine powder is observed to have settled at the bottom. Then pour off the liquor from this powder, which is to be gradually dried. From the liquor still coloured, the rest of the colouring matter may be separated by the solution of tin, when it yields a carmine little inferior to the former. Florentine-lake, the kind in general use, and known by the name of lake, is used in water, and also in oil, but does not stand ; it is a very beautiful colour at first, and there is no substitute that will completely answer the purposes of lake. The best sort is prepared from the sediment of cochineal that remains in the kettle after making carmine, adding a small quantity of cochineal or brazil-wood, and precipitating the colouring matter with a solution of tin. - Madder-lake, a colour lately brought into use, is not so bright and rich a colour as the last-mentioned lakes. It has this valuable advantage, it stands much better, and answers many of the purposes of Florence-lake. Rose-lake, generally called rose-pink, is made by a basis of chalk, coloured by Brazil or Campeachy wood. It does not stand, and is only used for house-painting and paper- hanging. Vermilion, is a bright scarlet pigment, formed from sulphur and quicksilver ; its brightness, and inclining to a crimson hue, denotes its goodness. It is a very useful colour in oil, and stands well; but as a water-colour it is apt to turn black. Red lead or minium, is lead calcined till it acquires a red colour, by exposing it with a large surface to the fire. It is also made from litharge, a calx or oxide of lead; but it is not so good as when made directly from metallic lead. This colour moderate ignition. is apt to become black, both in water and oil. It is therefore seldom used, but for very coarse purposes. - Indian red, is sometimes used instead of lake, and it might be useful, had it not the property of appearing stronger after some time. Never use it as a water colour. In oil, this effect does not take place. - - . Venetian red, is a native red ochre, rather inclining to the scarlet than the crimson hue ; it differs little from the common Indian red. It is fouler, and chiefly used by house-painters. Spanish brown, an earthy substance, ſound in the same state in which it is used ; is nearly of the same colour as Venetian- red, but coarser. It is only used for the commonest purposes, though it does not change. - Light red, or burnt ochre, is common yellow ochre, heated red-hot, till the colour changes from a yellow to a red. It is an excellent colour, both in water and oil, having the quality of standing well. - - - Red chalk, the same substance used for drawing on paper, in the manner of a crayon, is very much like light red, and is . used instead of it, for some purposes. It stands well, and is used both in water and oil. Burnt Terra di Sienna, made by calcining raw terra di Sienna till it acquires a red colour, a very rich tint, and much used in water and oil, as it stands well in both. Blue Colours. —Ultramarine, is prepared from lapis lazuli, by calcining and washing it very clean. When genuine, it is the brightest, the most beautiful of all colours, and stands well. It is much valued, and used in oil, and means have been found to levigate it sufficiently for water-colour drawings. Ultramarine ashes, the residuum after washing the lapis . lazuli, in which a portion of the ultramarine still remains, is very subject to be adulterated, and not so bright as ultrama- rine, being like that colour with a tint of red and white in it, yet when genuine it stands well. - Prussian blue, is iron combined with prussic acid. It is made in the following manner:—Two parts of purified potash are intimately blended with three parts of dried and finely pulverized bullock’s blood. The mass is first calcined in a covered crucible, on a moderate fire, till no more smoke or flame appear; after this, it is brought to a complete, yet Or equal parts of potash and finely pow- dered coals, prepared from bones, horms, claws, &c. are mingled, and heated in a covered crucible to a moderate redness. Either of these two calcined masses is, after cooling lixiviated with boiling water, and the lixivium filtered. Nothing remains now but to make a solution of one part of green vitriol and two parts of alum; and to add to it, while yet hot, the above lixivium, little by little however, and to separate the greenish-blue precipitate, which then forms, by means of a ſiltre. If afterwards a slight quantity of diluted muriatic acid be affused upon this precipitate, it assumes a beautiful dark blue colour. The operation is terminated by edulcorating and drying the pigment thus prepared. Prussian blue is an extremely beautiful colour when properly prepared, and stands tolerably well. Common Prussian blue is apt to contain some iron, which causes it to turn greenish or olive. - Verditer, a blue pigment, obtained by adding chalk or whitening to the solution of copper in aquafortis, is prepared by the refiners, who employ for this purpose the solution of copper, which they obtain in the process of parting, by preci- pitating silver from aquafortis by plates of copper. Common verditer is made in Sheffield and Birmingham, from the sulphate of copper. Verditer is only used for coarse 'purposes, and chiefly by paper-stainers. It has been sometimes called Sandel's blue, from the term cemdres-blues, or blue ashes. g Indigo, extracted from a plant called the aniſ, that grows in the East and West Indies, is not so bright as Prussian blue, but it has the advantage of being more durable. It is the blue generally used in drawings. It cannot be dissolved by water, bnt may by the sulphuric acid : it then forms Scott's liquid blue, used for colouring silk stockings, &c. Smalt is a glass covered with cobalt, and ground to a fine powder. Its coarseness prevents its being used much for painting in oil or water. It is employed sometimes by strew- ing it upon a ground of oil paint. It is also used in enamel painting and the colouring of porcelain, as it stands well. C O L C () M 18|: DICTIONARY OF MECHANICAL SCIENCE. Bice, is smalt more finely levigated. . - Yellow Colours.-Indian yellow, the brightest of all yellows for water-colours, is not durable. - from the urine of the buffalo. In India, it is a common and cheap colour; the natives using it for colouring their calicoes, which they do without any mordant, so that the colour is washed out again when the cloth is dirty. *. - King's yellow, is orpiment refined, a substance dug out of the earth, and consisting of sulphur joined to arsenic; it may also be prepared by subliming sulphur with arsenic. It is of a bright yellow, but does not stand well; it is a strong poison, and great caution must be used in employing it. - Naples yellow, a very durable and bright yellow, comes from Naples. It is prepared from lead and antimony. Yellow ochre, an earth naturally coloured by oxide of iron, is a cheap colour, and not very bright, but valuable, because it stands well. Roman ochre is a superior yellow ochre, of a rich tint. . Dutch pink, formed of chalk, coloured with the juice of French berries, or other vegetables affording a yellow colour, does not stand, and is chiefly used for common purposes. Gamboge, a gum brought from the East Indies, dissolves readily in water, and is a fine serviceable yellow. It is used Only in water. Masticot, an oxide of lead, prepared from calcining white lead, is very little used, the colour not being bright. Gall stones. This is a hard substance, formed in the gall- bladders of oxen; or it may be obtained from the gall of other animals. It is a rich colour, but does not stand. Raw Terra di Sienna, a native ochreous earth, brought from Italy, is a fine warm colour, and stands well. French berries. A liquor may be extracted from these, useful as a stain for coarse purposes; but it does not keep its colour, Turmeric root and saffron, may be used for similar purposes. Orange-lake, is the tinging parts of arnatto, precipitated together with the earth of alum. It does not stand. Brown pink, is the tinging part of a vegetable substance precipitated upon the earth of alum. It is a rich greenish yellow, but does not stand. Green Colours.-There are few colours so useful as green; and it is, therefore, the practice with artists to form their greens by the mixture of blue and yellow, and by varying these, a vast variety of green tints are obtained. Sap green, is the concreted juice of the buckthorn berries. It is used only in water, and is employed chiefly in flower- painting, colouring prints, &c. Verdigris, is an imperfect oxide of copper, combined with a small portion of acetite, carbonic acid, and water. It is prepared in large quantities, chiefly in France, near Montpel- lier, by stratifying copperplates with the husks of grapes, yet under various fermentation, which soon grow acid, and corrode the copper. After the plates have stood in that situation for a sufficient time, they are moistened with water, and exposed in heaps to the air. The verdigris is scraped off from their sur- face as it forms. Verdigris is of a bluish-green colour, it has no body, does not stand, and is only used for coarse purposes; it answers best in varnishes. Distilled verdigris, sometimes called crystilis verdigris, is prepared from common verdigris, by dissolving it in vinegar. It is of a very bright green, and is used chiefly for varnishes, and in colouring maps, &c. Brown Colours.--Bistre, is the finer part extracted from the soot of burnt wood. It is used alone for sketches in water- colours, being a transparent water colour. Roman bistre, is a very excellent but scarce kind of bistre, imported from Rome. Cologne earth, a mineral substance of a dark blackish brown colour, is a very useful pigment; what is generally sold in the shops for Cologne earth is an artificial mixture. Raw umbre, a native ochreous earth, of a light brown, stands well. ** Burnt umbre, is only the last mentioned colour calcimed in the fire. It then acquires a rich deep brown, and is of great use, being a fine colour, that stands well. Asphaitum, used in oil, is of a very rich deep brown. It is 20. a transparent, or glazing colour that will not work in water, , but when dissolved in turpentine, it becomes an useful sub- It is said to be procured stance for giving deep and spirited touches to drawings. The linens in which the Egyptians wrapped their mummies were dipped in asphaltum. White Colours.-Flake white, is an oxide of lead, formed by corroding lead with vegetable acids, or vinegar. White lead is the same as flake white, but of an inferior quality. It is the only white used in oil-painting, and is there- fore a very useful colour; in water it always turns black. Egg-shell white, and oyster-shell white, are only egg-shells or oyster-shells calcined ; the animal gluten is thus destroyed, leaving the lime behind, which soon attracts the carbonic acid again from the atmosphere. Well-washed Spanish white, or common whitening, answers the same purpose. Permanent white, is a white sold in the shops under this name, and it will not change; but great care must be employed in using it, as it is made from barytes, a deadly poison. Black Colours.—Lamp black, the soot of oil, collected after it is formed by burning, is very generally used, both in oil and water, and Stands perfectly well. Ivory black, the charcoal of ivory or bone, formed by giving them a great heat, while they are deprived of all access of air: it is used both in oil and water. Blue black, the coal from burning vine-stalks in a close vessel, is like ivory black, with a tint of blue. Indian Ink.-The Indian ink is used in China for writing with a brush, and for painting upon the soft Chinese paper. It has been ascertained, both from experiment and information, that the cakes of this ink are composed of lamp black and size, with the addition of some perfuming substances, not essential to it as an ink. The fine soot obtained by holding a plate over the flame of a candle or lamp, and mixed up with clean size, makes an ink in every respect equal to the Chinese. Colouring Prints.-Persons who wish to colour prints should wash them first with alum water, which will prevent the colour from sinking, besides giving a lustre and brightness to them. For this purpose, boil four ounces of alum in a quart of clear water, till the alum is dissolved. CoLou R, in Physics, a property inherent in light, by which it excites different vibrations in the optic nerve, and which being sent to the sensorium, affect the mind with different sensations. COLOURING, in Painting, the art of disposing the tints so as to produce either, an imitation of the natural colours of the objects represented, or of force and brightness of effect. COLUBER, a genus of serpents, of which there are ninety- seven species. - COLUMBA, the Pigeon, a genus belonging to the order of passeres, of which there are about seventy species, natives of different countries. COLUMBA NOACHI, Noah's Dove, is one of the new con- stellations, situated still more to the south, directly below Lepus; and it lies on the west of Argo Navis and Canis Major, whence its place in the heavens may be easily found. There are twenty-six stars in this asterism ; one of these is of the 2d magnitude, one of the 3d, two of the 4th, &c. COLUMN, in Architecture, a round pillar, made to support and adorn a building, and composed of a base, shaft, and capital. Column, in the Military Art, a long and deep file of troops or baggage. COLURES, in Astronomy, are two great circles passing through the poles of the world; one of them passes through the equinoctial points, Aries and Libra; the other through the solstitial points, Cancer and Capricorn; hence they are called the equinoctial and solstitial colures. They divide the ecliptic into four equal parts, and mark the four seasons of the year. COLYMBUS, the Diver, in Ornithology, a genus of anseres, of which there are several species. COMA, a preternatural propensity to sleep, which however the patient cannot enjoy, but wakes again immediately. COMA BERENICES, Berenice's Hair. Berenice was the wife of Euergetes, a king of Egypt; and when he went upon a dangerous expedition, she vowed to consecrate her fine head of hair to Venus, if he returned in safety. . Some time after the return of Euergetes, the locks, which were hung up in the 3 A 182 C O M C O M DICTIONARY OF MECHANICAL SCIENCE. temple of Venus, disappeared, and Conon, an astronomer, publicly reported that Jupiter had made them a constellation. The cluster of stars composing Coma Berenices, is very remarkable, there being so many of the 4th and 5th magnitudes. The boundaries and contents of this asterism are: north by Cames Wenatici, east by Boötes, 'south by Leo and Virgo, and west by Leo and Ursa Major. This constellation contains 43 stars, ten being represented of the 4th magnitude, and the remainder of less magnitudes. - COMB, an instrument for disentangling flax, wool, hair, &c. Combs are made of the horns of bullocks, of elephant's teeth, tortoise shell, and box or holly wood. Bullocks’ horns are prepared by sawing off the tips, then holding the horns in the flame of a wood fire till they become soft. In this state they are slit open on one side, and pressed in a machine; then plunged into water, from whence they come out hard and flat. They are next sawn into proper lengths, and to cut the teeth, each piece is fixed in a tool called a clam. The teeth are cut with a fine saw, or rather a pair of saws, and they are finished with a file. The process for making ivory combs is nearly the same as the above. A method has beeen recently invented for cutting combs by machinery. ... - COMBINATION, in Chemistry, the union of bodies of different natures, thereby producing a new compound body. COMBINATIONS, in Mathematics, denote the different collections that may be formed out of any given number of things, taking a certain number at a time, without regard to the order in which they may be arranged; and are thus dis- tinguished from perm.utations, or changes, which have reference to the order in which the several quantities may be disposed. 1. When only two are combined.—One thing admits of no combination. Two, a and b, admit of only one, viz. a b. Three, a, b, c, admit of three, ab, ac, be. Four, of six, viz. ab, ac, ad, be, bd, cd. Five, of ten, viz. ab, ac, ad, ae, be, bd; be, cd, ce, de. Whence the numbers of combinations of two and two only, proceed according to the triangular numbers, 1, 3, 6, 10, 15, 21, &c. which are produced by the continual addition of the original series, 0, 1, 2, 3, 4, 5, &c. And if n be the number of things, the formula for expressing the sum of all their combina- tions by two's, will be m. m. — 1. 1 .. 2 - 2 . 1 Thus, if n = 2; this becomes — = 1. 2 If n = 3; it is 3 .. 2 4. 3 — = 3. If n = 4; — E 6, &c. 2 2 2. When three are combined together, three things admit of one order, a, b, c. Four admit of four, viz. abe, abd, acd, bed. Five admit of ten ; abe, abd, abe, acd, ace, ade, bed, bee, bde, cde. And so on according to the first pyramidal numbers, 1, 4, 10, 20, &c. which are formed by the continual addition of the former, or the triangular numbers, 1, 3, 8, 10, &c. And the general formula for any number n of combinations, taken by three's, is 77 . m — 1. n. — 2 1 . .2 . 3. 3. 2. 1 . - 4.3.2 So if n = 3; it is = 1. If n = 4; it is — E 4. 1. 2. 3 ... 6 º 5 . 4. . 3 . If n = 5 ; it is — E 10. 6 -º- Proceeding thus, it is found that a general formula for any number m of things, combined by m at each time, is s = n . n – 1 ºn — 2. m. — NY, &c. 1 .. 2. 3. , 4. continued to m factors or terms, or till the last factor in the denominator be m. So in six things combined by four's, the number of combinations is, 6 . 5 , 4 .. 3 - 15 1 .. 2 . 3 . 4 8. By adding these together, the sum will be the whole num- ber of possible combinations of n things, combined by two's, three's, four's, &c. And all the series are the co-efficients of the power n of a binomial, wanting only the first two, l and n, therefore the sum will be Tºx il” — n – 1, or, 2" — m — 1. If the number of things be five, then 2" – l = 32 – 6 = 26. 4. To find the number of changes and alterations which a num- ber of quantities can undergo, when combined in all possible varieties of ways with themselves and each other, both as to the things themselves, and their order and position. One thing admits of one order or position. . Two may be varied four ways, as aa, ab, ba, bb. Three quantities taken by 'two's, may be varied nine ways, as aa, ab, ac, ba, ca, bb, be, cb. cc. in like manner four things taken by two's, may be varied 42, or 16 ways; and five things, by two's, 5*, or 25 ways. Thus also when taken by three's the changes will be n°, and when taken by four's they will be n°, and so generally when taken by n’s they will be ºn ", wherefore, adding all those together, the whole number of changes or combinations in n, things taken by two's, by three's, by four's, &c. to m's will be the sum of the geometrical series, n + 1* + n°-H n° . . . . m.”, ºn.” – 1 which sum is E + m. For example, if the number of 77 – 1 44 – 1 255 - | things n be four, this gives × 4 = - X 4 = 340. 4 — 1 3 COMBUSTIBLE. A body which, in its rapid union with others, causes a disengagement of heat and light. To deter- mine this rapidity of combination, a certain elevation of tempe- rature is necessary, which differs for every different combus- tible. Combustibles have been arranged into simple and compound. The former consists of hydrogen, carbon, boron, sulphur-phosphorus, and nitrogen; besides all the metals. The latter class comprehends the hydrurets, carburets, sulphu- rets, phosphurets, metallic alloys, and organic products. COMBüSTION was defined under the word Chemistry, to be the act of a body burning in a gas capable of supporting flame. We will here treat of these supporters of combustion; and first, they have the property of shining in the dark. Various kinds of animal and vegetable substances seem to have a great deal of this kind of phosphorus; the glow-worm is a remarkable instance. Dead fish, rotten sea-weed, and numbers of insects, have this property in a great degree. Instruments for measuring the degree or intensity of light, are called photometers. Effects of Light upon the Photometer. - Light of the sun at an elevation of 30°, sky perfectly clear, 75° Idem, sky white, . . . . . . . . . . . . . . . . . . . . . . . . . ... • * * * * * * * ~ * 730 Light of the blue sky at an elevation of 45°, . . . . . . . . . . . . . . 56° Zenith, . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 490 A cloudy sky, . . . . . . . . • a s a • e s e e e s e e o e s e º e º 'º e º 'º º " " ... ſº tº 9 sº º 539 A full moon, . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 349 Moon five days old, . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200 Light from snow enlightened by the sum, . . . . . . . . . . . . . . . . 570 - from snow in the shade, . . . . . . . . . . . . . . . . . . . . . . . . . . 47o — Starry sky, March 14, 1817, . . . . . . . . . . . . . . . . . . . . . . 7o Sky clear of stars, March 14, 1817, . . . . . . . . . . . . . . . . 70 5. Planet Venus at an elevation of 30°, April 5, 1817, . . . . . . . 9° Simple Supporters of Combustion.—Oxygen. . For the purpose of obtaining oxy- gen or any other gas, the annexed apparatus will prove the most elegant and gene- rally useful. D is a stand with rings, supporting a retort C, and an Argand's lamp E ; the latter is connected with the stand by a screw (see F); A is a pneumatic trough made of tin, and containing water, from the retort, ascends into C O M C O M 183 IOICTIONARY OF MECHANICAL SCIENCE. the glass jar B, placed upon a wooden shelf;-as the gas ascends into the jar, the water is displaced. G is a strong tube of glass, in which gases are detonated or inflamed by electricity. For common purposes, and where heat is, not required, a matrass with a - bent glass tube fit- ted to it, is used, as represented in the furthest figure. This may be done with a common phial and hand- basin, according to the nearest figure. A is the matrass; F the bent tube; C the phial ; and D the basin. Oxygen, is a substance known only in combination with other bodies, and has never been obtained alone. It is absorbed by combustible bodies, and converts them into acids. Oxygen is necessary for combustion, uniting itself always to bodies which burn, augmenting their weight, and changing their properties. It is necessary for the respiration of animals. It is a consti- tuent part of atmospheric air, of water, of acids, and of all bodies of the animal and vegetable kingdoms. Combined with light and caloric, it constitutes oxygen gas. When a body has only a small quantity of oxygen united to it, not sufficient to make it an acid, it is called an oxide. Thus, most of the metals can only be reduced to the state of oxides by the addi- tion of oxygen. This was formerly called calcination, and the metal added to oxygen was called a calx. Thus, the calx of mercury, of tin, &c. When the base has only just a sufficient quantity of oxygen to exhibit the properties of an acid, the termination ous is used, such as the Sulphureous acid, the phosphorous acid, &c.; but when it has a greater portion of oxygen, the termination ends in ic, as Sulphuric, phosphoric, and nitric acid. - Chlorine, is assimilated to oxygen as an elementary sub- stance. In the gaseous state it is of a yellowish green colour, and it is this property which suggested its name. Its odour is extremely disagreeable. Chlorine is not capable of being respired; and even when mixed in very small quantities with common air, it renders it extremely pernicious to the lungs. It has never been found pure in mature; but exists in many com- pounds, particularly in table or sea salt. Iodine, is obtained from sea-weeds, such as barilla and kelp : like chlorine and oxygen, when in the state of vapour, it sup- ports combustion. Its vapour is of a violet hue : it is obtained in brown shining scales. Fluorine, is the supposed base of fluoric acid obtained from fluor-spar; but it has never yet been obtained in a separate State. - Combustible and Non-combustible Substances.—Carbon. Modern chemists consider the diamond as pure crystalline carbon. The diamond is one of the hardest bodies known ; for it resists the most highly tempered steel file, and can be ground or polished only by diamond powder. It takes an exquisite and lasting polish. It has a great refractive power; and hence its lustre, when cut into the form of a regular solid, is uncommonly great. The diamond, like other combustible bodies, burns by a strong heat, with a sensible flame, attracting oxygen, and becoming wholly converted into carbonic acid gas during that process. It combines with iron by fusion, and like common charcoal; converts it into steel. Common charcoal, the base of animal and vegetable matters, is widely diffused throughout nature. It is a compound of carbon with earths, alkalies, salts, &c. united to a portion of oxygen ; it is properly an oxide of carbon. It is black, sonorous, and brittle ; and is obtained from many substances, but chiefly from wood. When pure, it resists the greatest heat in close vessels. With nitrate of potash, it detonates in a hot crucible, leaving a fixed alkali behind. It does not mix with the metals, but restores their oxides to a metallic state. . • * • Sulphur or brimstone, is a simple combustible substance, which nature frequently presents in a pure state. It is found in the earth in a loose powder, or in a solid state; and either detached or in veins. It is found also in the neighbourhood of volcanoes, and is deposited as a crust on stones contiguous to them. It is frequently met with in mineral waters, sometimes also in coal mines, and it is found in combination with most of the metals; when united to iron, it forms martial pyrites, or sulphuret of iron. In order to form it into rolls, it is melted and poured into wooden moulds; it is then called roll sulphur. Flowers of sulphur are formed by subliming purified sulphur with a gentle heat in close chambers. Sulphur is a non-con- ductor of electricity, and hence it becomes electric by friction— º unites to most of the metals; rendering them brittle and usible. Phosphorus, is commonly found united to oxygen, in the state of phosphoric acid, which is found plentifully in different animal, vegetable, and mineral substances. It is a yellowish Semitransparent substance, of the consistence of wax. It is luminous in the dark, at the common temperature of the - atmosphere. It takes fire spontaneously, and burns rapidly in the open air, (at 122° of Fahrenheit,) with a brilliant white flame, and is converted into phosphoric acid. The combusti- bility and luminous property of phosphorus have given birth to various experiments, and the following will evince its charac- teristic properties in a pleasing manner. That phosphorus burns at the usual temperature, appears by writing with it upon black or purple paper, or any other smooth surface. The writing will be luminous in the dark, as if on fire. The fiery appearance vanishes by blowing upon it, but becomes visible again after a few seconds. The combination of any substance with sulphur, phosphorus, or charcoal without oxy- genation, has the termination of its name in et ; thus sulphur and iron form sulphuret of iron, phosphorus and lime form phosphuret of lime. • Hydrogen. As hydrogen gas is produced by a different process from other gases, we insert the annexed cut. C is a furnace, through which an irom tube or gun barrel, EF, passes. ||||| sº In this tube there is a quantity of iron filings, over which the steam of water proceeding from a retort A, placed in a large crucible V, passes, and is decomposed; the oxygen of the water combining with the iron filings, whilst the hydrogen is - set free, to pass (~. Mººr),s}) E" through a vermi- Žººl" . jº cular tube Rinto a A == T-ſº gas bottle H, and # º from thence by &# ſº º the tube K into ſmil ń any convenient |v ° ſº º ; : { > º' gen is one of the - - constituent ele- ments of water. It is also one of the ingredients of bitumen, of oils, fat, ardent spirits, ether, and in fact of animal and vegetable bodies; it also forms a part of all animal and vege- table acids; and it is one of the bases of ammonia, and of various compound gases. It possesses so great an affinity for caloric, that it can be obtained only in the state of gas. It is consequently impossible to procure it in the concrete or liquid state, independent of combination. Hydrogen united to caloric and light, forms hydrogen gas. Hydrogen gas united to car- bon, forms carburetted hydrogen gas, by which streets, shops, theatres, and churches are lighted. Nitrogen, called also azote, is a simple body, very abundant in nature, though not producible in an uncombined state. It is one of the component parts of atmospheric air, and also of all animal and vegetable bodies, nitric acid, and ammonia. It enters into combination with light and caloric. This com- pound is called nitrogen gas. - Boron, is a powder of a brown colour; inodorous and insipid ; electric ; incombustible in covered vessels, but increases in density when the heat is augmented; insoluble in ether, oils, alcohol, and water. Silian, is a powder of a dark colour, incombustible at a high temperature. - COMET, an opaque, spherical, and solid body, like a planet, performing revolutions about the sun in elliptical orbits, having the sun in one of their foci. See ASTRONOMY. COMMEN DAM, a benefice or ecclesiastical living, which being void, or to prevent its becoming so, is committed com- 184 C O M DICTION ARY OF C O M MECHANICAL SCIENCE. mendatur, to the care of a clerk, to be supplied till a proper pastor is appointed. When a person is made a bishop, his benefice is void by the promotion; but if the king give him power to retain it, he is said to hold it in commendam. COMMERCE, in a general point of view, is usually dis- tinguished into two kinds, the commerce of import and of export; but there is little reason for this distinction, for what- ever a nation imports, it must have paid an equivalent for to the country of which it is purchased, and consequently the two branches are intimately dependent, and could not exist sepa- rately for any considerable period. The value obtained in foreign markets, for the goods or manufactures which a nation exports, repays the labour of procuring or manufacturing them, with a profit to the master manufacturer and to the exporting merchant; and this value being invested in foreign produce, which on importation affords a further profit to the merchant, it is evident that the transaction, while it supports individuals, makes a real addition to the wealth of the country, by the greater value of the returns imported beyond that of the goods exported. Commerce, therefore, while it is the means of pro- curing a mutual interchange of conveniences between distant countries, and of extending knowledge and civilization over every part of the globe, contributes essentially to the strength and influence of the countries by which it is encouraged. COMMISSARY, in the ecclesiastical Law, an officer of the bishop, who exercises spiritual jurisdiction in places of a diocese so far from the episcopal see, that the chancellor can- not call the people to the bishop's principal consistory court, without giving them too much inconveniency. º COMMISSARY GENer AL of THE MUSTERs, an officer appointed to muster the army as often as the general thinks proper, in order to know the strength of each regiment and company, to receive and inspect the muster-rolls, and to keep an exact state of the strength of the army. CoMMISSARY General of Stores, an officer in the artillery, who has the charge of all the stores, for which he is accountable to the office of ordnance. CoMMISSARY General of Provisions, an officer who has the inspection of the bread and provisions of the army. COMMISSION, in common Law, the warrant or letters- patent which all persons, exercising jurisdiction, have to empower them to hear or determine any cause or suit; as the commission of the judges, &c. Most of the great officers, judicial and ministerial, of the realm are made also by com- mission. By means of commission, oaths, cognizance of fines, answers in chancery, &c. are taken, witnesses examined, offices found, &c. CoMMISSION of Bankruptcy, is the commission that issues from the lord chancellor, on a person's becoming a bankrupt within any of the statutes, directed to certain commissioners appointed to examine into it. COMMITMENT, in Law, the sending of a person charged with some crime to prison by warrant or order. A commitment may be made by the king and council, by the judges of the law, the justices of peace, or other magistrate, who have authority by the laws and statutes of the realm so to do. COMMITTEE of PARLIAMENT, a certain number of mem- bers appointed by the House for the examination of a bill, making report of an inquiry, process of the house, &c. When a parliament is called, and the speaker and members have taken the oaths, there are committees appointed to sit on certain days, viz. the committee of privileges and elections, of religion, of trade, &c. which are standing committees. Sometimes the whole House resolves itself into a committee, on which occasion each person has a right to speak and reply as often as he pleases, which is not the case when the House is not in a committee. COMMON, is a right of privilege which one or more persons claim to take or use, in some part or portion of that, which another man's lands, waters, woods, &c. naturally produce, without having an absolute property in such lands, woods, waters, &c. COMMON LAw, that body of rules received as law in Eng- land, before any statute was enacted in parliament to alter the same.—The common law is grounded upon the general customs of the realm, including the law of nature, the law of God, and the principles and maxims of law. It is also founded on reason, as said to be the perfection of reason acquired by long study, observation, and experience, and refined by the learned in all ages. It may likewise be said to be the common birthright, that the subject has for the safeguard and defence not only of his goods, lands, and revenues, but of his wife, children, life, fame, &c. Our common law, it is said, after the heptarchy, was collected together into a body by divers of our ancient kings, who commanded, that it should be observed through the kingdom ; and it was, therefore, called common law, because it was common to the whole nation, and before only affected certain parts. . - COMMON PLEAS, one of the king's courts held in West- mister Hall, wherein a lord chief justice and three puisne justices preside. In personal and mixed actions it has a con- current jurisdiction with the court of king's bench, but has no cognizance of pleas of the crown. . - COMMONS, in Parliament, are the lower house, consisting of knights elected by the counties, and of citizens and burgesses by the cities and borough towns. - COMPANY, a society of merchants, tradesmen, or others, united in one common interest. When there are only two, three, or four, thus associated, it is called a partnership; the word company being usually restrained to a considerable num- ber of members associated by prescription or charter. The mechanics of all towns incorporated are thus formed into companies, which have charters of privileges and immunities. In London they are numerous, and many of them are very rich. In a commercial sense, the term company denotes a large association formed for the purpose of trade; thus we have the Hamburgh company, the oldest trading establishment in the kingdom, incorporated in 1295; the Russia company, confirmed by charter in 1566; the Eastland company, settled in 1579; the South Sea company, formed in the reign of Queen Anne ; the East India company, originally established in 1606; and, lastly, the Hudson's Bay company, first chartered in 1670. CoMPANY, in the army, a body of foot commanded by a cap- tain, who has under him a lieutenant and an ensign; the number of men from 50 to 80. COMPARATIVE ANATOMY, is that which considers the bodies of other animals, serving for the more accurate distinc- tions of several parts, and supplying the defects of human subjects. Comparative, however, does not strictly stand in contradistinction to human anatomy; but while it embraces the whole circle of animated existence, considers man as the standard of its comparisons, and the primary object of its inquiries. COMPARISON, in Rhetoric, a figure which illustrates one thing by resembling it to, and comparing it with, another, to which it has a manifest relation. COMPASS, as represented in the annexed figure, an instru- ment employed by pilots to ascertain the ship's course at sea, consisting of a circu- lar box, containing a paper card. The card, which repre- sents the horizon, is divided into 32 equal parts, by lines drawn from the centre to the circumference, called points or rhumbs; the intervals between the points are also subdi- vided into halves and quarters, and also the whole circumference into equal parts called degrees, 360 of which complete the circle, - and consequently the distance, or angle, comprehended between any two rhumbs, is equal to 114 degrees, or 15 minutes. The four principal points are called the cardinal points, two of which, opposite to each other, are called the north and south points; that which is toward the right hand when we look north, is termed the C O M C O M 185 DICTIONARY OF MECHANICAL SCIENCE. east, and its opposite the west point; the names of all the inferior ones are compounded of these according to their situa- tion. Along the north and south line is fixed a small bar of steel, termed the needle, which, being touched by the load- stone, acquires a certain virtue, whereby it hangs nearly in the plane of the meridian, and consequently, determines the direction of the other points towards the horizon. This card and needle having a small socket in the centre, is supported on the point of a fine pin of steel, the whole being confined in the circular box, with a glass cover, which box is hung in gimbals to counteract the motion of the ship. A Square box, with a moveable lid, serves to support the gimbals, and secures the compass from accident in removals. The “Board of Longitude” have voted £500 to Peter Bar- low, for a very simple invention of curing the local attraction of ships, by placing abaft the compass, a plate of iron, which being regulated so as to correct the effects of the ship in any place, does the same in all places. COMPASSES, BEAM, a machine to draw large circles or arcs. The beam may be any length from 2 to 6 feet, armed with two cursors of brass, one fixed and the other moveable. These cursors may be formed of points of brass, steel, pencils, &c. and the fixed cursor has sometimes an adjusting micro- meter screw applied to it, for the more ready obtaining of eXtents. . CoMPAsses, or Pair of Compasses, a mathematical instrument for describing circles, measuring and dividing lines or figures, &c. The common Compasses consists of two sharp-pointed branches or legs, of iron, steel, brass, or other metal, joined together at the top by a rivet, about which they move as on a centre ; and are too well known to need any particular description. CoMP Asses of three Legs, or Triangular CoMPASSES ; the construction of which is like that of the common compasses, with the addition of a third leg or point, which has a motion every way. Their use is to take three points at once, and so to form triangles, and lay down three positions of a map to be copied at the same time. : Cylindrical and Spherical CoMPAsses, consist of four branches, joined in a centre, two of which are circular and two flat, a little bent at the ends : their use is to take the diameter, thickness, or caliber of round or cylindric bodies, such as guns, pipes, &c. Elliptic CoMPAsses. These are used for drawing ellipses, or ovals of any kind ; they consist of a beam A B, about a foot long, . bearing three cursors, to one of which may be screwed any point or pencil ; to the bottom of the other two are riveted two sliding dove- tails, adjusted in grooves made in the cross branches of the instru- ment. These having a motion every way, by turning about the long branch, go backwards and forwards along the cross ; so that when the beam has gone half way about, one of these will have moved the whole length of one of the branches, and when it has got quite round, the same dove- tail has got back the whole length of the branch ; and the same may be repeated on the other side. The distance between the two sliding dove-tails is the distance between the two foci of the ellipsis; so that by changing that distance, any proposed ellipse may be described. German CoMPASSES, have their legs a little bent outwards, towards the top ; so that when shut, the points only meet. Hair COMPASSES, are so contrived within side, by a small adjusting screw to one of the legs, as to take an extent to a hair’s breadth. Proportional CoMPAsses, are those in which the joint lies, not at the end of the legs, but between the points terminating each leg. These are either simple or compound. In the former scrt the centre or place of the joint is fixed; so that one pair of them serves only for one proportion. In the compound ones the joint may be set at any distance, and consequently any proportion whatever easily obtained. . Spring CoMPAsses, or Dividers, are made of hardened steel, ſplication. with an arched head, which by its springs opens the legs; the opening being directed by a circular screw fastened to one of the legs let through the other, and worked with a nut. Geometry of the CoMP Asses, a species of geometry invented by M. Mascheroni, of Milan, by which all the elementary problems of plane geometry are performed by the compasses only, without the use of the ruler. COMPLEMENT of an ARCH or ANGLE, is what it wants of 90 degrees; thus the complement of 50° is 40°, and the com- plement of 40° is 50. Arithmetical CoMPLEMENT, of a logarithm, is what the loga- rithm wants of 10:00000, &c.; and the easiest way"to find it is, beginning at the left hand, to subtract every figure from 9, and the last from 10. So the arithmetical complement of 8'2501396 is 17498604. It is commonly used in trigonome- trical calculations, when the first term of a proportion is not radius; in that case, add together the logarithms of the 3d, 2d, and arithmetical complement of the first term, and subtract 10 from the result. CoMPLeMENT, in Astronomy, denotes the distance of a star from the zenith ; or the arch comprehended between the place of the star above the horizon and the zenith, being the same as is otherwise called the co-latitude. CoMPLEMENTs of a Parallelogram, are the two smaller parallelograms made by drawing two right lines through a point in the diagonal. - - COMPLEX TERMs or IDEAs, in Logic, are such as are com- pounded of several simple ones. Complea Proposition, is that which has at least one of its terms complex ; or such as con- tain several members as casual propositions, or its several ideas offering themselves to our thoughts, by which we are led to affirm the same thing of different objects. Thus, neither kings nor people are exempt from death. COMPLEXION, a term technically denoting the tempera- ment, habitude, and natural disposition of the body ; but popularly signifying the colour of the face and skin. COMPOSITION, in Grammar, the joining of two words together; or prefixing a particle to another word, to change, or lessen, or augment its signification.-In Logic, composition is a method of reasoning, by which we proceed from a general truth to particular ones.—In Music, composition is the art of adapting sounds to airs, songs, &c. either in one or more parts, for the voice or instrument.—In Painting, composition denotes the choice and disposition of the figures of a picture. CoM Positio N, in Commerce, a contract between an insolvent debtor and his creditors, by which the latter agree to take a part of the debt in compensation for the whole. CoM Position, or Composing, in Printing, is the arranging of the types or letters in the composing-stick, in order to form a line; and of several lines ranged in order in the galley, to make a page; and of several pages, to make a form. CoMPosition of Motion, in Mechanics, is an assemblage of several directions of motion resulting from several powers. acting in different though not opposite directions. CoM Position of Proportion, is the comparing the sum of the antecedent and consequent with the consequent, in two equal ratios, as, suppose 4 : 8 :: 3 : 6, they say by composition of proportion 12 : S : ; 9 : 6. The same holds of the sum of the antecedent and consequent compared with the antecedent; thus we say, 12 : 4 : ; 9 : 6. There is a great difference between composition of proportion by addition and by multi- See PROPORTION. - COMPOST, in Husbandry and Gardening, several sorts of soils or earthy matters mixed together, to make a manure for assisting the matural earth in vegetation. - * COMPOUNDS, PRIMARY, in Chemistry, are: 1. Alkalies, earths, oxides, acids, and compound combustibles. Secondary compounds are combinations of earths with each other, and with metallic oxides; combinations of earths with alkalies ; combinations of acids with alkalies, earths, and metallic oxides ; combinations of sulphuretted hydrogen with alkalies, earths, and metallic oxides; and lastly, combinations of oils with alkalies, earths, and metallic oxides. - COMPREHENSION, in Rhetoric, puts the whole for a part, or a part for the whole. COMPRESSIBILITY, in Philosophy, that quality of a body 3 B 186 C O N .C O. N. DictionARY OF MECHANICAL SCIENCE. or fluid, by which it yields to the pressure of another body or force, so as to be brought into a narrower compass. The com- pressibility of water was for a long time doubted by philoso- phers, and the famous Florentine experiment seemed for a time to decide the question in the negative. But water is really compressible into less than its natural bulk, and is more so in winter than in summer; but with spirits of wine and oil of olives, the contrary takes place, these being most compres- sible in the latter season. The following table shews the quantity of compression of these fluids and mercury, when the thermometer was at 50°, and barometer 29% inches. - Compression of Millionth parts. Specific gravity. Spirits of wine, ......... 66 ................ 846 Oil of olives, ... . . . . . . . . 48 . . . . . . . . . . . . . . . . 9|8 Rain water, . . . . . . . . . . . . 46 . . . . . . . . . . . . . . . . 1000 Sea water, .......... . . . 40 . . . . . . . . . . . . . . . . 1028 Mercury, ..... • - - - - - - - - - 8 . . . . . . . . . . . . . . . . 13595 Whence these fluids are not only compressible, but elastic; but that their degree of compressibility is not, as might have been expected, in the inverse ratio of their densities. * . COMPUTATION, the method of estimating time, weights, measures, &c. . - CONCAVE, an expression used to denote the curvilinear vacuity of hollow bodies. - CoNCAVE Lenses, or Mirrors, have either one or both sides concave. See LeNs and MIRRoR. CONCAVITY, from concave, the hollow or vacuity of bodies. CONCAVO-ConCAVE Lens, is that which is concave on both sides. ConcAvo-Convex Lens, is that which is concave on one side, and convex on the other. CONCENTRATION, the bringing things nearer to a centre: whence the particles of salt water are said to be concentrated by evaporating the watery part. CoNCENTRATION, in Chemistry, the act of increasing the strength of fluids, which are rendered stronger by abstracting a portion of the mere menstruum. This is generally effected by evaporation, where the menstruum is driven off at a lower heat an is required to drive off the substance with which it is united. CONCENTRIC, having a common centre, as concentric circles, ellipses, &c. - CONCESSION, in Rhetoric, a figure by which something is allowed that yet might be disputed, in order to obtain another point. CONCHOLOGY. The study of shells, or testaceous ani- mals, is a branch of natural history, though not greatly useful in human economy, yet by the beauties of the subjects of which it treats, is adapted to recreate the senses, and insensibly lead to the contemplation of the glory of the Divinity in their creation. The term conchology comprehends the study of all animals which have a testaceous covering, whether inhabitants of the marine element, fresh water, or the land. Testaceology is a term synonymous with conchology, but is of later origin and application. CONCLAVE, the place in which the cardinals of the Romish church meet and are shut up, in order to the election of a pope. The conclave is a range of small cells, ten feet square, made of wainscot: these are numbered, and drawn for by lot. They stand in a line along the galleries and hall of the Vatican, with a small space between each. Every cell has the arms of the cardinal over it. The conclave is not fixed to any one deter- minate place, for the constitutions of the church allow the car- dinals to make choice of such a place for the conclave as they think most convenient; yet it is generally held in the Vatican. The conclave is very strictly guarded by troops; neither the cardinals, nor any person shut up in the conclave, are spoken to but at the hours allowed of, and then in Italian or Latin: even the provisions for the conclave are examined, that no letters be conveyed by that means from the ministers of foreign powers, or other persons who may have an interest in the election of the pontiff. - CONCOCTION, in Anatomy, &c. may be defined the action of fitting our daily aliment for the support and nourishment of our bodies; and also the description of all that disposition of parts and mechanism of system which unite in effecting that change in our food by which it is converted into blood, chyle, &c. To have a clear idea of the manner in which concoction is performed, we must distinguish it into three stages: the first is performed in the progress of the aliment from the mouth down to the lacteals; which are vessels that receive the chyle from the intestines; the second is performed in the passage of the milky liquor called chyle, through the lacteal vessels to the loins, and then up under the collar bone, where it mingles with the blood; the third, or ultimate stage of concoction, is performed by the circulation of the blood and chyle together through the lungs, and the whole arterial system. In all these stages, the design seems evidently to have been to grind and dissolve the aliment, and to incorporate it with a large quantity of animal juices already prepared, and reduce it at last to the very same substance with our blood and humours. g In the first stage of concoction, by a curious configuration of parts, and action of muscles, adapted to their respective func- tions, our food is ground small by the teeth, and moistened by a copious saliva in the mouth. It is in the next place swal- lowed, and conveyed down the gullet, where it is farther mollified and lubricated by a viscid unctuous humour, distilled from the glands of that canal. From thence it slips into the stomach, where several causes concur towards its complete dissolution. It is diluted by the juices, swelled and subtilized by the internal air, and it is macerated and dissolved by the heat which it meets with in the cavity. It is also agitated and attenuated by the perpetual friction of the coats of the stomach, and the pulsation of the arteries there ; by the alter- nate elevation and depression of the diaphragm or midriff in breathing; and by the compression of the strong muscles of the belly. After a proper stay, it is gradually propelled into the intestines, in the form of a thick, smooth, uniform, ash- coloured fluid. - . . . . When our aliment, thus prepared, arrives at the intestines, it is there mixed with three different sorts of liquors. It receives two kinds of bile; the one, thick, yellow, and extremely bitter, from the gall-bladder; the other, scarcely bitter, or yellow, but in a much larger quantity, from the liver. The third liquor that falls here upon the food, issues plentifully from a large glandular substance, called the pancreas or sweet- bread, and is a limpid mild fluid, like the saliva, which serves to dilute and sweeten what may be too thick and acrimonious. The two saponaceous biles resolve and attenuate viscid sub- stances; incorporate oily fluids with aqueous ones, making the whole mixture homogeneous; and by their penetrating and detergent qualities, render the chyle fit to enter the lacteal veins, into which it is conveyed, partly by their absorbent nature, and partly by the peristaltic motion of the intestines. If we now consider the change which our aliment has under- gone, in the mouth, gullet, and stomach, together with a large quantity of bile, and pancreatic juice poured upon it in the intestines ; and if we reflect also on the incessant action of the muscles, blending, churning, and incorporating the whole, we shall readily perceive, that their united agency must alter the flavours and properties of the different kinds of food, in such a manner as to bring the chyle nearer in its nature to our animal juices, than to the original substances from which it was formed. Our food, thus changed into chyle, constitutes the first stage of concoction; and we shall find the same assimila- tion carried on through the second. • The next stage begins with the slender lacteal veins, where they arise from the intestines by an innumerable multitude of invisible pores, through which the fine, white, fluid part of the chyle is strained or absorbed ; while, at the same time, the gross, yellow, fibrous part, conveyed slowly forward, and fur- ther attenuated in the long intestinal tube, is perpetually press- ed and drained of its remaining chyle, until the dregs, becom- ing at last useless, are ejected out of the body. These lacteal veins issue from the intestines in various directions, sometimes straight, and then oblique, often uniting and growing larger, but presently separating again. They frequently meet at acute angles, and enter into soft glands dispersed through the me- sentery, from which they proceed larger than before, and more turgid, with a fine lymphatic fluid : in most places also they run contiguous to the mesenteric arteries, by whose pulsation their load is pushed forward. And thus, after various commu- nications, separations, and protrusions, the lacteal veins pour C O N c o N 187 DICTIONARY OF MECHANICAL SCIENCE. their chyle into a sort of cistern or reservoir formed for that purpose, between the lowest portion of the diaphragm and highest vertebre of the loins. It is very remarkable, that these veins are furnished with proper valves, which permit the chyle to move forward, but effectually stop its return ; and that a great number of veins purely lymphatic, as well as the lacteal ones, empty themselves into the same cistern. - - In all this contrivance it is evident, that the chyle, being more and more diluted and blended with abundance of lymph from the glands through which it passes, and from other sources, approaches still nearer to the nature of our animal juices, and consequently becomes more fit for nutrition. The chyle is pushed from its reservoir into a narrow transpa- rent pipe, called the thoracic duct, which climbs in a perpen- dicular direction by the side of the back-bone, from the loins up to the collar-bone, and opens into the subclavian vein : where, by the peculiar arrangement of several small valves, the chyle mingles gently with the blood after it has been | thoroughly elaborated, and attenuated with lymph from every part of the thorax, or great cavity of the breast, and is from thence soon conveyed to the heart. Thus we may perceive, that by a wonderful mechanism, a large quantity of chyle and lymph is forced upwards, in a perpendicular course, through a thin slender pipe; but to render this more plain, the following particulars must be attended to:—First, to the progress of the chyle, urged forward and continued from the antecedent action of the intestines, and the beating of the mesenteric arteries. Secondly, to the motion of the diaphragm and lungs, in respiration, pressing the thoracic duct that lies under them, whilst the thorax, rising and falling, resists their action, whereby the duct is squeezed between two contrary forces, and the liquor which it contains pushed upwards. Thirdly, this duct runs close by the side of the great artery, (called by anatomists, the superior portion of the descending aorta,) whose strong pulsation presses its yielding sides, and compels the chyle and lymph to mount in an upright ascent. Fourthly, it must be observed, that this duct is accommodated with valves, which permit its contents to move upwards by every compression, but never to fall back again. Thus terminates the second stage of concoc- tion, when the chyle falls into the heart. And it may be seen, that in the progress through these two stages, our aliment has been mixed accurately with all the substances or principles which compose the blood, viz. saliva, mucus, lymph, ibile, water, salts, oil, and spirits. The most fluid and subtile parts of our aliment, before and after it is elaborated into chyle, pass into the blood by certain absorbent veins dispersed all over the mouth, gullet, stomach, and intestines: when we consider how quickly refreshments and strength are communicated to weary, faint, and hungry people, immediately upon drinking a glass of good wine, or eating any cordial spoon-meat, this remark will appear the more obvious. The third stage begins where the chyle mingles with the blood, and falling soon into the right ventricle of the heart, is from thence propelled into the lungs. It will appear that the lungs are the principal instruments of converting the chyle into the blood; especially if we consider their structure, first with regard to the air-vessels of which they are composed, and secondly, with regard to their blood-vessels; for we shall then clearly perceive the change which their fabric and action must produce on the chyle. - The windpipe is composed of segments of cartilaginous rings on the fore part, to give a free passage to the air in respi- ration; and of a strong membrane on its back part, to bend with the neck, and give way to the gullet in deglutition. This pipe is lined throughout with an infinity of glands, which perpetually distil an unctuous dense humour to lubricate and anoint the passages of the air. Soon after the windpipe has descended into the cavity of the breast, it is divided into two great branches; and these two are subdivided into innumerable ramifications called bronchia, which become smaller in their progress, (not much unlike a bushy tree inverted,) until at last they terminate in millions of little bladders which hang in clusters at their extremities, and are inflated by their admis- sion of air, and subside at its expulsion. The clusters consti- tute the lobes of the lungs. * = . The blood-vessels of the lungs next deserve our attention. The branches of the pulmonary artery run along with those of the windpipe, and are ultimately subdivided into an endless number of capillary ramifications, which are spread like a fine net-work over the surface of every individual air-bladder; and the pulmonary vein, whose extreme branches receive the blood and chyle from those of the arteries, run likewise in form of a net over all the air-bladders of the bronchia. w ... From this admirable structure of the lungs, it is obvious, that the crude mixture of the blood and chyle, passing through the minute ramifications of the pulmonary artery and vein, is compressed and ground by two contrary forces, viz. by that of the heart, driving the mixture forward against the sides of the bronchia and air-bladders; and by the elastic force of the air equally repelling this mixture from the contrary side. By these two opposite forces, the chyle and blood are more intimately blended and incorporated; and by the admission and expulsion of the air in respiration, the vessels are alter- mately inflated and compressed, (and probably some subtile air or aether is received into the blood,) by which means the mixture is still farther attenuated and dissolved; and after various circulations through the lungs and heart, and the whole arterial system, is at last perfectly assimilated with the blood, being fitted to nourish the body, and answer the different purposes of animal life. - - - When the blood, thus prepared from the aliment, is, by repeated circulations, gradually drained of all its bland and useful parts, and begins to acquire too great a degree of acrimony, it is carried off by both sensible and insensible eva- cuations, through the several channels and distributions of nature. By these evacuations the body is made Hanguid, and requires a fresh supply of aliment; while at the same time the saliva, and juices of the stomach and intestines, becoming thin and acid by multiplied circulations, vellicate the nerves of those passages, and excite hunger, as a faithful monitor, to remind us of that refreshment which is now become necessary. CONCORD, in Grammar, is the same with syntax, in which the words of a sentence perfectly agree : that is, in which mouns are in the same gender, number, and case ; and verbs in the same number and person with nouns and pronouns. CoNCORD, in Music, is the union of sounds, and is either perfect or imperfect; perfect concords consist of the fifth and eighth, the imperfect of the third and sixth. CONCORDANCE. This word has been applied appro- priately to a sort of dictionary of the Bible, explaining the words thereof in alphabetical order, with the several books, chapters, and verses quoted in which they are contained. Its chief use is to enable a person to find out any text of scripture, of which he is able to recollect any of the chief words. * CONCORDAT, a covenant or agreement with the pope con- cerning the acquisition, permutation, and resignation of eccle- siastical benefices. Most Catholic sovereigns have such, a treaty with the pope. - - - CONCRETE NUMBeRs, are those which are made to denote any particular thing, as three pounds, three guineas, &c. and are thus distinguished from abstract numbers, which have reference to no particular subject or thing, as 3, 4, &c. CONCRETIONS, MoRBID, hard substances in different parts of the animal body. - CONDENSATION, the act whereby a body is rendered more dense, compact, and heavy. Condensation is, by most writers, distinguished from compression, by considering the latter as performed by some external violence; whereas the former is the action of cold. . CONDENSER, a pneumatic engine, or syringe, whereby an uncommon quantity of air may be condensed into a given space; so that sometimes ten atmospheres, or ten times as much air as there is at the same time, in the same space, without the engine, may be thrown in by means of it, and its egress prevented by valves properly disposed. It consists of a brass cylinder, wherein is a moveable piston; which being drawn out, the air rushes into the cylinder through a hole pro- vided on purpose; and when the piston is again forced into the cylinder, the air is driven into the receiver through an orifice, furnished with a valve to prevent its escape. See AIR GUN. - 188 C O N C O N DECTIONARY OF MECHANICAL SCIENCE. CONDIMENTS. These are not properly alimentary mat- ters, or such as become ingredients in the composition of the animal fluid; yet they are taken with advantage along with the proper aliments, the digestion and assimilation of which they, in some degree, modify. They are of two kinds, saline or acrid; having this acrimony, for the most part, residing in their oily parts. To this list of condiments, we may add capsicum, ketchup, and soy, observing, that the whole of the seasonings consist of salt, vinegar, and aromatics, combined together; and if they are taken only in the quantity necessary to render the food more sapid, they may increase the appetite, and favour full eating; but they can hardly otherwise do harm, unless when the aromatics are taken in such large quantity as to weaken the tone of the stomach, - CONDITION, in Civil Law, a clause of obligation, stipu- lated as an article of a treaty or contract, legacy, &c. In the Common Law, condition is a restraint annexed to any thing, so that by the nonperformance the party shall sustain loss, and by the performance receive advantage. - the electric fluid. CoNDuctor, in Electricity, a term first introduced into this science by Dr. Desaguliers, and used to denote those || substances which are capable of receiving and transmitting electricity; in opposition to electrics, in which the matter or virtue of electricity may be excited and accumulated, or retained. The former are also called non-electrics, and the latter non-conductors. And all bodies are ranked under one or other of these two classes, though none of them are perfect electrics, nor perfect conductors, so as wholly to retain, or freely (and without resistance to transmit, the electric fluid. To the class of conductors belong all metals and semimetals, ores, and all fluids, (except air and oils,) together with the ice, (unless very hard frozen) and snow, most saline and stony Substances, charcoals, of which the best are those that have been exposed to the greatest heat; smoke, and the vapour of hot water. It seems probable, that the electric fluid passes through the substance, and not merely over the surfaces of | metallic conductors; because, if a wire of any kind of metal be covered with some electric substance, as resin, sealing-wax, &c. and a jar be discharged through it, the charge will be con- ducted as well as without the electric coating. It has also been alleged, that electricity will pervade a vacuum, and be transmitted through it almost as freely as through, the sub- stance of the best conductor; but the electric spark or shock would no more pass through a perfect vacuum than through a Stick of solid glass. In other instances, however, when the vacuum has been made with all possible care, the experiment. has not succeeded. It has also been observed, that many of the forementioned substances are capable of being electrified, and that their conducting power may be destroyed and reco- | wered by different processes: for example, green wood is a | conductor ; but baked, it becomes a non-conductor; again, its conducting power is restored by charring it; and lastly, it is destroyed by reducing this to ashes. Again, many elec- tric substances, as glass, resin, air, &c. become conductors by being made very hot; however, air heated, by glass must be excepted. w CONDUCTOR, Prime, is an isolated conductor, so connected with the electrical machine, as to receive the electricity immo- diately, from the excited electric. . . . . . CoNDUCTORS of Lightning. are pointed metallic rods fixed to the upper parts of buildings, to secure, them from strokes of lightning. These were invented and proposed by Dr. Frank- Jin for this purpose, soon after the identity of electricity and lightning was ascertained; and they exhibit, a very important and useful application of modern discoveries in this science. This ingenious philosopher having found that pointed bodies are better, fitted for receiving and throwing off the electric fire than such as are terminated by blunt ends or flat surfaces, and that metals are the readiest and best-conductors, soon disco- Yered that lightning and electricity resembled each other in this and other, distinguishing properties; he ºtherefore recom- mended a pointed metalline rod, to be raised some feet above the highest part of a building, and to be continued down into CONDUCTOR, any body which receives and communicates the axis of the cone. classes, according to the magnitude of the angle at the vertex, A B C is acute, or less than a right angle. ; Cone has its side A B equal to the diameter of the base A. C. the ground, or the nearest water. The lightning, should it ever come within a certain distance of this rod or wire, would be attracted by it, and pass through it in preference to any other part of the building, and be conveyed into the earth or water, and there dissipated, without doing any damage to the building. Many facts have occurred to evince the utility of this simple and seemingly trifling apparatus. And yet some electricians have objected to the pointed termination of this conductor, preferring rather a blunt end ; because they con- ceive a point invites the electricity from the clouds, and attracts it at a greater distance than a blunt conductor. ." CONE, is a solid body having a circular base, and its other extremity terminated in a single point or vertex. Cones are either right or oblique. A Right Cone, is that in which the right line joining the vertex and centre of the base, is perpen- - dicular to the plane of the base ; as A B C. A right cone may be conceived to be generated by the revolution of the right- angled triangle B D C, about its perpen- dicular B D. And thus, Euclid defines: a cone to be a solid figure, whose base is a circle, and is produced by the entire revo- lution of the plane of a right-angled tri- angle about its perpendicular, being called Tight comes are distinguished into A- |->}o made by a plane passing through that point perpendicular to: the base. An Acute-angled CoME, is that in which the angle An Equilateral An Obtuse-angled Cone, is that in which the angle A B C is obtuse, or greater than a right angle, . A Right-angled CoME, * g º º is that in which the angle A B C is a right angle. substances containing them, the effluvia of flaming bodies, An Oblique Cone, is that in which the line joining the vertex and centre of the base is not perpendicular, but oblique, to the plane of the base; as L. M. N. This solid, which is not treated of by the ancient geometricians, is evidently not included in the preceding definition, that having reference to the right cone only. It has therefore been an object with the moderns to render the above more general, so as to include both cases under one and the same general definition or description, which is as follows:–If a line W A con- tinually pass through the point V, turn- ing upon that point as a joint, and the lower part of it be carried round the cir- cumference A B C of a circle ; then the space enclosed between that circle and the path of the line is a cone. The circle A B C is the base of the come, V the ver- tex, and the line W D the axis; D being the centre of the circle. . Properties of the Cone,—1. Every cone, whether right or oblique, is equal to one- third of a cylinder of equal base and altitude. And therefore the solidity of a MC | cone is found by multiplying the area of its base by one-third of its perpendicular altitude. 2. The curve surface of a right cone is equal to a circular sector, having its radius equal to the slant height of the cone, and its area equal to the whole cir- cumference of the cone’s base. And therefore this surface is equal to half the product of the slant side into the circumference of the base. 3. The surface of an oblique cone is not quad- rable; indeed no rule has yet been found that will even lead to a practical approximation of its area, notwithstanding the attempts of several ingenious and able mathematicians. 4. The solidity of a cone with an elliptic base, forming part of a right cone, is equal to the product of its surface by a third of one of the perpendiculars, drawn from the point in which the axis of the right cone intersects the ellipse; and it is also equal to one-third of the height of the cone multiplied by the area of the elliptic base. Consequently, the above perpendicular is to the height of the come, as the elliptic base is to the curve sur- face. See Dr. Barrow’s “Lectiones Geometrica.” C O N C O N DICTIONARY OF MECHANICAL SCIENCE. 189 Frustum of a Cone, is that which is formed by cutting off the upper part of a cone, by a plane parallel to its base; as the figure A B C D. CoNEs of the higher kinds, are those whose bases are circles of the higher kinds; and are generated by supposing a right line fixed in a point above, though conceived capable of being ex- tended more or less, on occasion; and moved or carried round a circle. CoNE of Rays, in Optics, includes all the several rays which fall from any point of a radiant, on the surface of a glass. CoNE, or Spindle (Double), in Mechanics, is a solid formed of two equal cones joined at their bases. If this be laid on the lower part of two rulers, making an angle with each other, and elevated in a certain degree above the horizontal plane, the cones will roll upwards towards the raised ends, and seem to ascend, though in reality the centre of gravity is descending lower. CONFESSION of an offence, is when a prisoner is arraigned, and his indictment being read, either he confesses the offence, or pleads not guilty. Confession is express or implied. Bxpress, is where one, in open court, confesses the crime, in the most satisfactory ground of conviction. Implied, is where the defendant, in a case not capital, yields to the king's mercy, and desires to submit to a small fine, which the court may accept, without requiring a direct confession. The presump- tion of guilt in this case is so strong, that the defendant cannot afterwards, in a civil action, deny the trespass. Confession, previous to trial, before a justice, &c., may also be given in evidence afterwards, as against the individual confessing; but it must be voluntary, not upon promise or threats, and must be taken in time. After confession, the party may take advantage of errors in the indictment, in arrest of judgment. Confession may also be, in a civil action, and is commonly on a warrant of attorney for that purpose, which being after accompanied with a bond, is vulgarly called a bond and judgment. CONFIGURATION, the exterior surface or shape that bounds bodies, and gives them their particular figure. CONFISCATE, from confiscare, and that from fiscus, the emperor's treasure. Any goods which being disclaimed by another, as a felon upon trial, comes to the king, although they are the felon's own. Those which he claims as his own, are, upon conviction, not confiscate, but forfeited to the king. CONFLUENT, in Medicine, an appellation given to the kind of small-pox, wherein the pustules run into each other. CONFORMATION, that make and construction of the human body peculiar to every individual; whence those diseases called organical, depend upon the mal-conformation of the parts. "... : - CONGE D’Eli Re, in ecclesiastical polity, the king’s permis- sion granted, under his signature, to a dean and chapter to elect a bishop. CONGELATION, the transition of a liquid into a solid state, in consequence of an abstraction of heat: thus metals, oil, water, &c. are said to congeal when they pass from a fluid into a solid state. With regard to fluids, congelation and freezing mean the same thing. Water congeals at 32°; and there are few liquids that will not congeal, if the temperature be brought sufficiently low. Every particular kind of substance requires a different degree of temperature for its congelation, which affords an obvious reason why particular substances remain always fluid, while others remain always solid, in the common temperature of the atmosphere; and why others are some- times fluid, and at others solid, according to the vicissitudes of the seasons, and the variety of climates. In consequence of the diminution of temperature, which is experienced as we ascend in the atmosphere, it is evident, that in every climate a point of elevation may be reached where it will be continually freezing. The altitude of the point above the surface of the earth, will depend partly on the tem- perature of the lower regions of the atmosphere, and partly on the decrement of heat belonging to the column at the period of observation. Thus, near the equator, it was observed by * that it began to freeze on the sides of the lofty 2}. 4 men : mountain Pinchencha, at the height of 13,577 feet above the level of the sea, whereas congelation was found by Saussure to take place on the Alps at the height of 13,428 feet. By tracing a line on the plane of the meridian, through the points at which it constantly freezes, a curve is obtained, which has been denominated the line of Perpetual Congelation. The height at which this curve intersects a vertical line in the various latitudes, has been computed by Kirwan, partly from observa- tion, and partly from the mean temperature of the parallel, and the decrement of heat, as we ascend in the atmosphere. The following table exhibits the result of his calculation; and though it is constructed on the erroneous supposition, that the mean annual temperature of the polé is 31°, which, according to the observations of Captain Scoresby and Captain Parry, must be far beyond the truth, it is tolerably accurate for the more accessible regions of the globe. Mean Height of Line Latitude. of Congelation. Latitude. Me!, §nt '0 . . . . . . . . . . . . . 15'577 45 . . . . . . . . . 7-658 ‘5 . . . . . . . . . . . . . 15°457 60 . . . . . . . . . . . . . 6'260 10 . . . . . . . . . . . . . I5'067 55 . .. 4'912 15 . . . . . . . . . . . . 15'498 60 . . . ... 3°684 20 . . . . . . . . . . . . . 13-719 65 . . . . . . . . . . . . 2°516 25 . . . . . . . . . . . . . 13-030 70 . . . . . . . © tº º e 1'557 30 . . . . . . . . . . . . 11 : 592 75 . . . . . . . . . . . . . •748 35 . . . . . . . . . . . . 10°664 80 . . . . . . . . . . . . . ‘l28 40 . . . . . . . . . . . . . 9°016 These numerical relations will be best perceived at a glance by means of the following diagram. H 14,000 12,000 10,000 8,000 6,000 4,000 2,000 E | of |zAT- 0. 10 20 30 40 60 70 80 Here EP represents the rectified meridian from the equator to the pole divided into intervals of 10° each; and the different perpendiculars or ordinates at the point 0, 10, 20, &c. represent the height of the freezing point at the equator, and at latitude 10, 20, &c. to the pole P. The curve HP, which has a con- trary flexure about 60°, exhibits the general form of the line of Perpetual Congelation from the equator to the pole. CONGRUITY, in Geometry, is the same as identity, those lines and surface being congruous, which will coincide or fill the same space. - CONGRUOUS QUANTITIES, are those which are of the same kind, and therefore admit of comparison; and quantities which cannot be so compared, are incongruous quantities. All abstract numbers are congruous; but concrete numbers are not congruous, unless the quantities they represent be so. Thus, 3 and 4, as abstract numbers, are congruous; but if they denote 3 pounds and 4 miles, they are incongruous. Hence it follows, that the method commonly given in books of arith- metic, for stating questions in the Rule of Three, is improper; because it supposes a comparison between quantities which are incongruous. We cannot say properly, that 3 pounds : 4 men :: 6 pounds : 8 men; but that 3 pounds : 6 pounds : : 8 men. CONICAL, any thing of a conical form, or relating to the COI!6. CoNICAL Ellipse, Hyperbola, Parabola, denote those figures, under their most simple form, as cut from the cone, to 3 C 50 90 190 C O N C O N DICTIONARY OF MECHANICAL SCIENCE. distinguish them from the same figures of a higher order. See the respective articles. - CoNICAL Ungula, or Conic Ungula, is a solid formed by a plane passing through the side and base of a cone, as the figure E C B F, fig. 1. CoNic Sections, as the name implies, are such curve lines and plane figures as tº are produced by the intersection of a plone with a cone. From the different positions of the cutting plane, there arise five different sections, viz. a triangle, ellipse, Y. parabola, and hyperbola. But only the three latter are particularly denominated comic sections. 1. If the secant, or cutting plane, pass through the vertex of the cone, and any part of the base, the section will evidently be a triangle, as AW B, fig. 2. 2. If the plane cut the cone parallel to the circular base, the section will be a circle, as Alb D. 3. If the plane pass through the side and base of the cone parallel to the other side; that is, if the cutting plane make the same angle with the base as the side of the cone makes, the section is a parabola, as D A B, fig. 3. e 4. When the plane cuts both sides of the cone, that is, when it makes with the base a less angle than the side of the cone makes, the section is an ellipse, as B.A. D. 5. When the plane passes through the side and base of the cone, making a greater angle with the base than the side or the cone makes, the section is an hyperbola, as D A E, fig. 4. And if the plane be continued to cut the opposite cone, this section is called the opposite hyperbola to the former, as Bed, fig. 6. 6. The vertices of any section are the points where the cutting plane meets the opposite sides of the cone, as A and B in the preceding figures. Hence the ellipse, fig. 5, and hyperbola fig. 4, have each two vertices, but the parabola only one, unless we consider the other as at an infinite dis- tance. - - 7. The aris, or transverse diameter, of a conic section, is the line joining its vertices, as AB; therefore the axis of an ellipse is within the figure, of the hyperbola without it, and in the parabola it is infinite in length, fig. 6. . 8. The centre of a conic section is in that point which bisects the axis. Hence the centre of an ellipse is within the figure, of the hyperbola without the figure, and in the parabola it is at an infinite distance from the vertex. The definition of the other lines, in and about the conic sections, will be found under their respective heads; and the principal properties of the different sections, under the articles ELLIPse, HYPER BOLA, and PARAbol A. The conic sections are of themselves a system of regular curves allied to each other, the doctrine of which is of the greatest use in physical astronomy, as well as in the physico- mathematical sciences, and has been much cultivated by both ancient and modern mathematicians. CONIUM, HeMlock, a genus of the digynia order, in the pentandria class of plants, and in the natural method belonging to the 45th order, umbellatae. There are five species. Conium maculatum, or the greater hemlock, grows naturally in Britain. It is a biennial plant. The stalk is smooth, spotted with pur- ple, and rises from four to six feet, branching out at the top with decompounded leaves. The flowers are white. It is a poison- ous plant, yet the internal and external efficacy of the hemlock has been proved in cancers, ulcers, and scrofulous tumors. CONJUGATE DIAMETER, or Axis of an Ellipsis, is the shortest of the two diameters, or that which bisects the trans- WerS6 ax1S. - - - , - CONJUGATION, in Grammar, a regular distribution of the inflexions of verbs in their different voices, moods, tenses, numbers, and persons, to distinguish them from each other. CONJUNCTION, in Astronomy, the meeting of two or more Stars or planets in the same degree of the zodiac. . CoNJUNCTION may be considered as either true or apparent. When the two bodies meet in the same point of both longitude and latitude, the conjunction is true; when they agree in lon- gitude, but differ in latitude, the conjunction is apparent. CoNJUNCTION is either heliocentric or geocentric.—Heliocentric conjunction is that which would appear to an observer at the sun; geocentric, that which would appear to one upon the earth.--Geocentric Conjunctions are either superior or inferior: thus, when a planet is seen on the same circle of latitude with the sun, but beyond him, the conjunction is called superior; when the planet is seen between the earth and sun, the con- junction is inferior.—Grand Conjunctions, are those wherein several of the planets are seen near together. M. de la Lande informs us, that on May 22, 1702, Jupiter and Saturn were within 194 of each other; on February 11, 1524, Venus, Mars, Jupiter, and Saturn, were very near each other, and Mercury not above 16° from them; on November 11, 1544, Mercury, Venus, Jupiter, and Saturn, were within the space of 10°; on March 17, 1725, Mercury, Venus, Mars, and Jupi- ter, were so near each other as to be all seen through the same telescope without altering its position; and on December 23, 1769, Venus, Mars, and Jupiter, were within 19 of each other.— The Chinese have a remarkable record of a conjunction of five planets, which happened in the time of their emperor, Tehuen- hiu; who, according to the Chinese annals, reigned from the year 2514, before Christ, to the year 2436, B.C.; and which is thought to prove the great antiquity of this empire, and of astronomical science amongst these people. : CoNJUNction, in Grammar, an inclinable word or particle, which joins words or sentences together, shewing their mutual relation and dependence. CONJURATION, strictly means combining together by oath, especially with evil spirits to do a public harm. The using of witchcraft, conjuration, &c. was felony by 1 Jac. c. 12: but that was repealed by 9 Geo. II. c. 5, and the offences and all prosecutions for them abolished; but if any pretend to witchcraft, or conjuration, or to tell fortunes, or from skill in occult or crafty science, to discover goods or chattels supposed, they shall be imprisoned a year, and stand in the pillory once a quarter, and may be ordered to give security for good beha- viour. The punishment of the pillory being abolished, they are only liable to the other penalties of the statute. CONOID, a solid figure generated by the revolution of any conic section about its axis; and hence receives particular denominations, according to the section from which it is pro- duced ; as ELLIPTICAL Conoid or Spheroid, PARABolic Conoid, and HYPERBolic Comoid; for which, see the respective articles. CONON, an ancient Greek mathematician, the friend of Archimedes. He was well skilled in geometry and astronomy, but is not celebrated for any particular discovery. CONSANGUINITY, the relation subsisting between persons of the same blood, or who are sprung from the same root. Consanguinity terminates in the sixth and seventh degree, excepting in the succession of the crown, in which case it is continued to infinity. Marriage is prohibited by the church to the fourth degree of consanguinity inclusive; but, by the law of nature, consanguinity is no obstacle to marriage, except it be in the direct line. CONSCIENCE, in Ethics, a secret testimony of the soul, whereby it gives its approbation to things that are naturally good, and condemns those that are evil. § CONSCRIPTS, men raised to recruit the French armies, All men capable of bearing arms in France and its dependen- cies are registered, and when called upon by the government, are obliged to join the army on any service. - CONSEQUENT, is the latter of two terms of a ratio, or that ：et ………………….….………： ， ， ，|- awael, wºwisi，！ºnr çº，）; ----ſae ···|-|- * * * * * ！rºws anjo，unaevae -------- · ####\，---- 5 -& {".| 10 ------------------ L·- T------- --- - --- - ！ !_）~，º º T！）， aevº ſºſ， ºvºſaesſo：！\º---- |- ºs aerodraet.， ! º'º， co aequae，' ·ſon： ： ： ： aeqna . |× × --~~~~---- |-|- ſi ）-- - _ ----！---- →（（（（）） TT：s sººA \，\！ſºwº©（） |- |- - （ ） |×|- ： \ ſae so praes）：\！ c o N C O N DICTIONARY OF MECHANICAL SCIENCE. I91 to which the antecedent is referred and compared; thus in the ratio a b, b is the consequent, and a the antecedent. - CONSEQUENTIA, a Latin term, commonly employed by astronomers to denote the real or apparent motion of a planet or comet, when it is moving from west to east, or according to the order of the signs; and is thus opposed to antecedendia, which denotes contrary motion. See ANTECEDENTIA. CONSIDERATION, in Law, the material cause or ground of a contract, without which the party contracting would not be bound. Consideration, in contracts, is something given in. exchange, something that is mutual and reciprocal ; as money given for goods sold, work performed for wages. And a con- sideration of some sort or other is so absolutely necessary to the forming of a contact, that a nudum pactum, or agreement to do or pay any thing on one side, without any compensation on the other, is totally void in law; and a man cannot be compelled to perform it. A consideration is necessary to create a debt. CONSIGNMENT, in Law and Commerce, is the sending or delivering over goods, money, &c. to another person, and is unconditional, or for a particular purpose. CONSISTENT Bodies, a term partially employed by philo- sophers, particularly by Boyle, to denote firm or fixed bodies, in opposition to fluid ones. - CONSISTORY, a tribunal ; every archbishop and bishop of every diocese hath a consistory court, held before his chancel- lor or commissary, in his cathedral church, or other convenient place of his diocese, for ecclesiastical causes. From the bishop's court the appeal is to the archbishop; from the arch- bishop’s court to the delegates. - - CONSOLIDATION, in Civil Law, is the uniting the posses- sion or profit of land with the property, and the contrary. It also denotes the uniting two benefices into one. CONSONANCE, in Music, is the effect of two or more sounds heard at the same time. - CONSONANT, a letter that cannot be sounded without a vowel before or after it. Consonants are divided into single and double; the double are a, and z, the latter are all single ; and these are again divided into mutes and liquids, the former are b, c, d, f, v, g, j, k, p, q, t, the liquids l, m, n, r. - CONSPIRACY, in Law, signifies an agreement between two or more, falsely to indict, or procure to be indicted, an innocent person for felony. . - CONSPIRATORS are, by statute, defined to be such as bind themselves by oath, covenant, or other alliance, to assist one another, falsely and maliciously to indict persons, or falsely to maintain pleas. - CONSTABLE, an officer whose duty it is to preserve the peace, and to arrest all public offenders who have committed the offence in his presence, or against whom he has the war- rant of a justice of the peace. There are many persons exempted by law from serving the office of constable; these are, the ancient officers of any of the colleges in the two univer- sities, counsellors, attorneys, and all other officers whose attendance is required in the courts of Westminster-hall, aldermen of London, the president and fellows of the fellowship of physic in London, surgeons and apothecaries in London, and within seven miles thereof, being free of the company of apothecaries, and licensed teachers, or preachers in holy orders, in a congregation legally tolerated, shall be exempted | from the office of a constable. The prosecutor of a felon to conviction, or the person to whom he shall assign the certificate thereof, shall be discharged from the office of constable. But generally speaking, every housekeeper, inhabitant of the parish, and of full age, is liable to fill the office of constable: he ought, however, to be of the abler sort of parishioners, as being more likely to perform his duty with probity and discretion. CONSTANT QuANTities, in Algebra, are those whose values are known, or which remain constantly the same. These are commonly denoted by the leading letters of the alphabet, a, b, c, &c. to distinguish them from the variable and unknown quantities, which are represented by the final letters, 2, y, z, &c. - êossiblEATION, in Astronomy, an assemblage or system of several stars, expressed and represented under the name and figure of some animal or other emblem. The ancients portioned out the firmament into several parts or constella- tions; reducing a "certain number of stars under the represen- tations of certain images, in order to aid the imagination and the memory, to conceive and retain their number and disposi- tion, and even to distinguish the virtues which astrologers attributed to them; in which sense a man is said to be born under a happy constellation, v. e. under a happy configuration of the heavenly bodies. The division of the heavens into constellations is probably as old as astronomy itself; at least it was known to the most ancient authors extant, whether sacred or profane, Job, chap. ix. ver, 9, “Which make h Arcturus, Orion, and the Pleiades, and the chambers of the south.” By the “chambers of the south,” Some have understood the constellations near the South pole, which are invisible to the inhabitants of the northern hemisphere. From the manner in which Job speaks of commerce, we may infer, that he lived in a country frequented by merchants, who imported thither the rarities of the south. Job, who lived in Arabia Petraea, among the merchants, might have derived from them his knowledge of the constellations. Chap. xxxviii. 31, 32, “Canst thou restrain the sweet influence of the Pleiades, or loosen the bands of Orion ? Canst thou bring forth Mazzaroth, (by which some understand the twelve signs of the zodiac,) or canst thouguide Arcturus with his sons? In the prophecy of Amos, who lived 790 years before Christ, we have the following exhortation, (chap. v. 7, 8:) “Ye who turn judgment into wormwood, and leave off righteousness in the earth ; seek him that maketh the Seven stars and Orion, and turneth the shadow of death into the morning, and maketh the day dark with night; that called for the waters of the sea, and poureth them out upon the face of the earth : the Lord is his name.” In this passage, the seven stars and Orion are mentioned as being well known, both by Amos, who was a herdsman of Tekoa, and the com- mon people, to whom this exhortation was addressed ; and we may hence infer, that the constellations had been invented for some time before that period. Some of the constellations are also occasionally mentioned by Hesiod and Homer, who flourished above 900 years before Christ; and Aratus of Tar- sus, the astronomical poet, who lived about 277 years before Christ, in his “Phenomena,” professedly treats of them all, except some few, which were invented after his time; shewing how each constellation is situated with regard to those that are near it, what position it bears with respect to the principal circles of the sphere, and what other constellations rise or set with it. See Zodi Ac. - e CONSTITUTION, an ordinance, regulation, or law made by authority of any superior, ecclesiastical or civil. CONSTITUTION, physically, is that particular disposition of the body, which results from the properties and mutual actions of the solids and fluids enabling them to exercise their proper functions. CONSTITUTIONS, ApostolicAL, a collection of regula- tions attributed to the apostles, and supposed to have been collected by St. Clement, whose name they likewise bear. It is the general opinion, however, that they are spurious, and that St. Clement had no hand in them. They appeared first in the fourth age, but have been much changed and corrupted since that time. - , - . - CONSTRUCTION, in Geometry, is the drawing those lines of a figure which are previously necessary for the making a demonstration more plain and evident. - CONSTRUCTION of EQUAtions, in Algebra, is the finding the roots of an unknown equation by the geometrical con- structing of right lines or curves; or the reducing given equa- tions into geometrical figure. And this is done by lines or curves, according to the order or rank of the equation." CONSUL, is an officer established by virtue of a commis- sion from the king, and other princes, in all foreign countries of any considerable trade, to facilitate and despatch business, and protect the merchants of the nation. The consuls are to keep up a correspondence with the ministers of England residing in the courts whereon their consulate depends. They are to support the commerce and the interest of the nation; to dispose of the sums given, and the presents made to the lords and principals of places, to obtain their protection, and prevent the insults of the natives on merchants of the nation. 192 C O N C.. O N DICTIONARY OF MEcHANICAL SCIENCE. \ CONTACT, in Mathematics, is when one line, plane, or body, is made to touch another, and the parts which thus touch are called the points of contact. CONTAGION, in Physic, the communicating a disease from one body to another. In some diseases it is only effected by an immediate contact, as in the syphilis; in others, it is con- veyed by infected clothes; and in others it seems capable of being transmitted through the air at a considerable distance. CONTENT, in Geometry, is the area or quantity of matter or space included within certain limits. - CONTIGUOUS ANGLes, in Geometry, are those which have one leg common to each angle. CONTINGENT, something casual or uncertain. Hence, future contingent, in logic, denotes a conditional event which may or may not happen, according to circumstances. Contin- gent is also a term of relation for the quota which falls to any person upon a division. Contingent use, in law, is that which is limited in a conveyance of lands, which may or may not happen to vest according to the contingency mentioned in the limitation of the use. A Contingent remainder is where no present interest passes; but the estate is limited to take effect, either to a dubious and uncertain person, or upon a dubious and uncertain event, so that the remainder may never take effect. - CONTINUED PROPORTION, in Arithmetic, is that where the consequent of the first ratio is the same with the antecedent of the second. CONTRABAND, in Commerce, a prohibited commodity, or merchandise bought or sold, imported or exported, in preju- dice to the laws and ordinances of a state, or the public pro- hibitions of the sovereign. Contraband goods are not only liable to confiscation themselves, but also subject all other allowed merchandise found with them in the same box, bale, or parcel, together with the horses, waggons, &c. which conduct them. There are contraband goods likewise, which, besides the forfeiture of the articles, are attended with several penalties and disabilities. CONTRACT, a covenant or agreement between two or more persons with a just consideration. Contracts are either express or implied. Express contracts are, where the terms are openly and plainly uttered ; implied, are those dictated by reason and justice: thus, if a man takes up goods without agreeing about the price. the law concludes, that he contracted to pay the real value. CONTRACTION, or DILATATION, an essential property of bodies, is best learned from experiment. We see that the volume of numerous bodies is enlarged or diminished, by the application of a vast force, or else of some delicate measure ; fluids may be expanded or condensed; hard substances enlarged or contracted. Thus, if a flaccid bladder be laid within the receiver of an air-pump, it will gradually swell as the exhaustion advances; but on restoring the external pres- sure, it will again shrink into its former dimensions. If a tall flask, nearly filled with water, be inverted in a jar of water, and placed likewise under a pneumatic receiver, the air collected near the top of the flask will visibly expand as the operation of pumping proceeds, till it presses down the water, and begins to make its escape from below in the form of rarefied bubbles. - - But air is easily compressed, by the opposite action of a syringe. In the vault or chamber of the air-gun, it is often condensed fifty or even eighty times. Nearly the half of that charge may be thrown into the pneumatic blow-pipe, from which, on partially opening the valve, it will again flow for the space of a quarter of an hour. Other gases are likewise notably contracted or dilated, by the increase or diminution of external pressure. But liquid substances themselves manifest a similar property, though in a much lower degree. If a large glass ball, terminating in a long narrow, and open stem, divided into minute spaces corre- sponding to the millionth parts of the whole capacity, be filled with distillèd'water, carefully purged of air, and introduced under the receiver of a pneumatic machine; as the exhaustion advances, the water will proportionally expand, and rise near fifty divisions; but, on admitting the atmosphere again to compress the water, it will sink to its former place in the stem. The contraction which the water suffers, 'at every increase of pressure, exceeds not indeed the 20,000th part of what air would undergo in like circumstances; but it is equally real, and evinces an inherent property. Mercury treated in the same way shews a contraction three times less than water. Alcohol, ether, oils, and the various acids and saline solutions, are all condensed or expanded, though in different degrees, by the change of atmospheric pressure. If the stem of the instrument now mentioned, were made to screw to the ball at a wide aperture, fragments of solid bodies could be easily introduced, and the vacant space filled up with water; the contraction of this portion of water being deducted from the contraction of the mixture, would give the distinct condensation of the hard materials. In this way, the compres- sibility of the various stones and metals could be accurately examined. The contraction and distention produced by external or internal pressure on glass, is quite visible in a thermometer with a large bulb and very long tube. When the mercury stands near the top of the scale, it will immediately rise on reclining the thbe, and will continue to flow till the thermo- meter has been reversed; but the mercury will again retreat, as the instrument is brought back to its vertical position. This experiment proves, that the bulb has its capacity sensibly enlarged by the thrust of the mercurial column. When long bars of wood, iron, or other metals, are laid horizontal on supports, they bend downwards by their own weight, and this depression is increased' by augmenting the incumbent pres- sure. The upper fibres are therefore drawn into a narrower curve than those at the middle of the bar, while the under fibres are extended into a wider convexity: the particles of the former are thus contracted, and those of the latter distended. It is likewise obvious, that in this incurvation, the contraction or dilatation induced will be proportional to the thickness of the bar. • The various kinds of wood are far more compressible than water, and suffer, hence, a very considerable degree of conden- sation, or being let down to great depths in the ocean. Pieces of oak, ash, or elm, plunged two or three hours in a calm sea, at the enormous depth of a thousand fathoms, and then drawn up, have been found to contain four-fifths of their weight of water, and to acquire such increase of density as indicates a contraction of the wood into about half its previous volume. The specimens which have undergone this singular change, if thrown into a pail of water, will sink like a stone. Hence probably the reason, why barks lost near the shore, are after- wards discovered by their timbers breaking up and floating to the surfaee; while the ships which founder in the wide ocean, acquiring permanent density from the vast compression they sustain, remain motionless at the bottom, and never rise again to disclose their fate. - .." But pieccs of wood, even of the softer kinds, whether round or square, may be easily squeezed in the direction perpendicu- lar to their fibres, by the action of a common vice. If allowed to stand only a few minutes under that compression, and imme- diately thrown into water, they will sink to rise no more. If the wood be kept much longer under the vice, it will take a set, and become constitutionally denser. Even cork may, by com- pression, be made to sink in water; but as its texture is nearly uniform, the force must be exerted on all sides. Into a thick and very strong glass cylinder, having a syringe adapted to it, introduce a large cork ball, and inject the air by quick and powerful strokes; the ball will gradually shrive!, till it has contracted even to less than one-third of its bulk ; but on allowing the charge of air to escape, the cork will speedily resume its former shape and dimensions. If the condenser be partly filled with water, on which the ball of cork is set to float, it will, under a like compression, though it has a minute por- tion of the liquid driven into its substance, shrink to nearly the same size as before, and soon fall to the bottom. Hence the success of the common experiment at sea, of letting down, in calm weather, to the depth of twenty or thirty fathoms, an empty corked bottle, and then drawing it up full of water, though the cork still remains in the neck. The water is not in this case forced through the pores of the cork as generally supposed, but the cork itself being condensed by the lateral C O N C O N 193 DICTIONARY | OF MECHANICAL SCIENCE, pressure of the incumbent mass, allows it to enter by the sides, and dislodge the air. Rodies are also contracted or dilated, from the operation of some internal cause. Thus, dry air is visibly expanded by its union with moisture. If, in a warm room, the inside of a tall iſask be wetted by a few drops of water, and thc mouth inverted in a basin of water, the contained air, in proportion as it becomes humified, will discharge, a copious stream of bubbles. On the other hand, a notable contraction of their joint volume is produced in the absorption of water by saw- dust, linen, , or bibulous paper. The combination of equal measures of water and alcohol is accompanied by a contraction amounting to the fiftieth part of the whole. A similar effect results from the solution of the sulphate of Soda, and other highly soluble salts. - . The alliage of different metals: often betrays a large contrac- tion. The power of tin to condense copper in the composition of bronze, was even remarked by the ancients, who combined these metals; in various proportions, to form their knives, chisels; or hatchets. Equal bulks of tin and copper are found to suffer a contraction amounting to not less than the fifteenth part of their whole volume. A liquid, in joining any solid substance, commonly occasions a general contraction; but the solid itself may yet by this accession expand with prodigious force. Thus dry peas being rammed into a gun barrel, and their interstices filled with water, will in a short time burst the barrel. In like manner, if wedges of soft dry wood be driven into slits made with a saw in blocks of freestone or marble, and then have water poured upon them, these wedges will quickly swell and rend the rock. Such was the ancient mode of quarrying, before the explosive power of gunpowder came to be introduced. It is still prac- tised in the art of cutting millstones in France, holes being bored at intervals in a line drawn across the block, and wooden plugs driven into them, and then wetted. Hence if the side of a thin piece of wood be moistened, it will bend backwards, the humidity insinuating itself into the soft parenchymatous matter between the fibres, and therefore | enlarging the circle of flexure. The thinner the wood is sliced, the greater will evidently be the incurvation produced by the wetting of its convex surface. The fibres of hair and wool, by the unequal rubbing and, moistening of their sides, are made to curl up, and to condense like a clue. On this property seems to be really founded the very 1mportant process of milling, fulling, or felting, by which a raw web of woollen cloth is thickened, and its texture rendered firm and compact. A leathern thong is extended by wetting, so are the filaments of flax and hemp.; though a cord is shortened by wet, the diameter of the coil being increased, and the extension of the overlapping fibres curtailed. A sponge dipped in hot water, and drawn more than once along a rope, it will in dry weather occasion, in one hour, a contraction of one-twentieth part of the whole length;--a remarkable property often advantageously employed as a mechanical agent. But the most powerful principle of internal expansion, is the introduction of heat; whose energies.vary exceedingly in different substances, but which can always be reduced to calculation, by comparing its effects with the opposite influence of external compression. Thus the same absolute portions of heat communicated to cylinders of one-inch diameter and height, of air, alcohol, water, mercury, and copper, would enable those columns respectively to sustain the weights of 10, 12, 3, and 2 pounds. gº. A remarkable phenomenon, of considerable importance in manufactures, obtrudes itself on our notice in this article, which is, the hardness that certain bodies acquire in conse- quence of a sudden contraction, and this is particularly the case with glass and some of the metals. Thus, glass vessels, suddenly cooled after having been formed, are so very brittle, that they hardly bear to be touched with any hard body. . The cause of this may be thus explained: when glass in fusion is very suddenly cooled; its external parts become solid first, and determine the magnitude of the whole piece, while, it still remains fluid within. . The internal part, as it cools, is disposed to contract still further, but its contraction is prevented by the resistance of the external, parts, which form an arch or vault round it, so that the whole is left in a state of constraint; and 21. as soon as the equilibrium is disturbed in any one part, the whole aggregate is destroyed. Hence it becomes necessary to anneal all glass, by placing it in an oven, where it is left to cool slowly; for, without this precaution, a very slight cause would destroy it. The Bologna jars, sometimes called proofs, are small thick vessels made for the purpose of exhibiting this effect; they are usually destroyed by the impulse of a small and sharp body; for instance, a single grain of sand, dropped into them, and a small body appears to be often more effectual than a larger one ; perhaps because the larger one is more liable to strike the glass with an obtuse part of its surface. CoNTRACTION, in Physics, the diminishing the extent or dimensions of a body, or the causing its parts to approach nearer to each other, in which sense it stands opposed to dila- tation or expansion. Water and all aqueous fluids are gradually contracted by a diminution of temperature, until they arrive at a certain point, which is about 8° above the freezing point; but below that point they begin to expand, and continue to do so according as the temperature is lowered ; and similar eſſects have been observed with regard to some metals. CONTRA-HARMONICAL PRopoRtion, in Arithmetic, is that relation of three terms, wherein the difference of the first and second is to that of the second and third as the third is to the first. te CONTRAVALLATION, in the Military Art, is a line formed in the same manner as that of circumvallation, to defend the besiegers against the sallies of the garrison. - CoNTRAVALLATION, or the Line of Comtravallation, in Fortifi- cation, a trench guarded with a parapet, and usually cut round about a place by the besiegers, to secure themselves on that side, and to stop the sallies of the garrison. See Fortification. €ONTROLLER, an officer appointed to control or oversee the accounts of , other officers, and, on occasion, to certify whether or no things have been controlled or examined. In England, we have several officers of this name—controller of the king's house, controller of the navy, controller of the cus- toms, controller of the mint, &c. CONTUMACY, in Law, a refusal to appear in court when legally summoned, or the disobedience of the rules and orders of a court having power to punish such an offence. In Eng- land, contumacy may be prosecuted to outlawry. CONVENTICLE, a private assembly or meeting, for the exercise of religion. The word was first attributed as an appellation of reproach to the religious assemblies of Wickliſſe, in this nation, in the reign of Edward III. and Richard II., and was afterwards applied to illegal meetings of nonconformists. CONVENTION, a treaty, contract, or agreement, between two or more parties. Every convention among men, provided it be not contrary to honesty and good manners, produces a natural obligation, and makes the performance a point of conscience. Every convention has either a name and a cause of consideration, or it has none; in the first case, it obliges civilly and naturally, in the latter only naturally. - . CoNvention, is also a name given to an extraordinary assembly of parliament, or the states of the realm, had without the king's writ; as was the convention of estates, who, upon the retreat of James II. came to a conclusion, that he had abdicated the throne, and that the right of succession devolved to King William and Queen Mary; whereupon their assembly expired as a convention, and was converted into a parliament. CONVERGENT; or Converg ING, the tendency of different things, variously disposed, to one common point. It is also sometimes used to denote an approximation towards the real value of a thing. - CoNverg ING Lines, those which tend to a common point. CoNverG ING Rays, those which tend to a common focus. . . CoN verGING Series, those series whose terms continually diminish. . . See SERIES. w - CONVERSE, in Mathematics, commonly signifies the same thing as reverse. Thus, one proposition is called the converse of another, when, after a conclusion is drawn from something supposed in the converse proposition, that conclusion is sup- posed ; and then, that which in the other was supposed, is now drawn as a conclusion from it: thus, when two sides of a triangle are equal, the angles under these sides are equal; and, on the converse, if these angles are equal, the two sides are equai. 3 D 194 C O O. C O O DICTIONARY OF MECHANICAL SCIENCE. Converse propositions are not necessarily true, but require a demonstration ; and Euclid always demonstrates such as he has occasion for. An instance or two will shew this. If two right-lined figures are so exactly of a size and form (both respecting their sides and angles) that being laid one on the other, their boundary lines do exactly coincide and agree, then no one doubts that these figures are equal. Now try the converse. If two right-lined figures are equal, then if they be laid the one on the other, their boundary lines exactly coincide and agree. It is manifest that this proposition, though the converse of the former, is by no means true. A triangle and a square may have equal areas; but it is impossible the sides of the former can all coincide with those of the latter. Again, if two triangles have their sides respectively equal, their angles will also be respectively equal, by Euc. i. 8. But, if two tri- angles have their angles respectively equal, it does not follow that the sides will be respectively equal: this may or may not be true, according to circumstances. Converse propositions, therefore, need a proof, notwithstanding this has been termed superfluous and impertinent by Emerson and some others. CONVERSION of Proportion, is when, of four proportionals, it is inferred that the 1st is to its excess above the 2d, as the 3d to its excess above the 4th.—Co Nversion, Centre of, in Mechanics. See Centre of Conversion. CONVEX, round or curved, or protuberant outwards, as the outside of a globular body. CONVEXITY, the exterior or outward surface of a convex or round body. . CONVEXO-ConcAve LeNs, is one that is convex on one side, and concave on the other.—Convexo-Convea: Lens, is one that is convex on both sides. CONVEYANCE, in Law, a deed which passes from one or more persons to others. CON VICT, in Common Law, a person that is found guilty of an offence by the verdict of a jury. The law implies, that there must be a conviction before punishment for any offence, though it be not mentioned in any statute. On a joint indict- ment, or information, some of the defendants may be convicted, and others acquitted. - CoNvict Recusant, a person who has been legally presented, indicted, and convicted, for refusing to come to church to hear the common prayer, according to the statutes 1 and 23 Eliz. and 3 Jac. I. CONVOCATION, an assembly of the clergy of England, by their representatives, to consult of ecclesiastical matters. It is held during the session of parliament, and consists of an upper and lower house. In the upper sit the bishops, and in the lower the inferior clergy. The convocation is now a mere form, and never enters upon business. CONVOLVULUS, Bind-Weed, a genus of the pentandria class and monogynia order, in the natural method ranking under the 29th order, campanaceae, of which there are 110 species. CONVOY, in Marine affairs, one or more ships of war, employed to accompany and protect merchant ships, and pre- vent their being insulted by pirates, or the enemies of the state in time of war. CoNvoy, in Military matters, a body of men that guard any supply of men, money, ammunition, or provisions, conveyed by land into a town, army, or the like, in time of war. CONVULSION, a preternatural and violent contraction of the membraneous and muscular parts of the body. CONUS, in Natural History, a genus of Vermes Testacea, is divided into five distinct families. There are upwards of seventy species enumerated. Many of the conus tribe are beautiful shells, and bear a high price on account of their rarity. We have no species of this genus upon the English coast. Some very curious kinds have been discovered in a fossil state in England, chiefly in the chalk cliffs of Hampshire. COOKERY, or Cooking, the exercise of art in the prepara- tion of food for human sustenance. It consists not only in the application of heat under various modifications and circum- stances, but also in the due intermixture of condiments, calcu- lated as well to please the palate as to promote nutrition. The exercise of this art is peculiar to man, and it has been deemed by naturalists one of his peculiar characteristics, that he is “a cooking animal.” Dr. Cullen says, that the cooking of vege- tables by boiling, renders them more soluble in the stomach, notwithstanding the degree of coagulation which their juices undergo. In the second place, the application of a boiling heat dissipates the volatile parts of vegetable substances, which are seldom of a nutritious nature, but, in many cases, have a tendency to prove noxious. In the third place, boiling helps to extricate a considerable quantity of air, that, in the natural state of vegetables, is always fixed in their substance; and it is probably in this way, especially, that heat contributes to the dividing and loosening the cohesion of their smaller parts. Thus, they are rendered less liable to ferment, and to produce that flatulence which is so troublesome to weak stomachs.--In the cookery of animal substances, some practices, previous to the application of heat, are to be considered as affecting the solubility in the stomach; particularly salting and pickling. These processes are spoken of under the article CoNDIMENTs. - . . The cookery of animal substances is of two kinds, as it is applied in a humid form in boiling and stewing; or in a dry form, in roasting, broiling, and baking. By the joint applica- tion of heat and moisture to meat in boiling, the texture is rendered more tender and soluble in the stomach; and it is only in this way that the firmer parts, as the tendinous, liga- mentous, and membranous parts, can be duly softened, and their gelatinous substance rendered subservient to nutrition. Yet these effects are different according to the degree of boil- ing. A moderate boiling may render their texture more tender, without much diminution of their nutritious quality; but if the boiling is extended to extract every thing soluble, the substance remaining is certainly less soluble in the stomach, and at the same time much less nutritious. But as boiling extracts, in the first place, the more soluble, and therefore the saline parts; so, what remains is, in proportion, less alkalescent, and less heating to the system. - Boiling in digesters, or vessels, accurately closed, produces effects very different from boiling in open vessels. From meat cooked in the latter, there is no exhalation of volatile parts; the solution is made with great success, and if not carried very far, the meat may be rendered very tender, while it still retains its most sapid parts; and this is esteemed always the most desirable state of boiled meat. If a small quantity of water only is applied, and the heat continued long in a moderate degree, the process is called stewing, which has the effect of rendering the texture of meat more tender, without extracting much of the soluble parts. This, therefore, leaves the meat more sapid, and in a state perhaps the most nourishing of any form of cookery, as we learn from the admirable essays and experiments of Count Rumford, who found very unusual effects produced on meat, by a low degree and long continued action of heat, both in the dry and humid way. The application of a dry heat in the cookery of meat is of two kinds, as it is carried on in close vessels, or as it exposed to the air. The first of these which we shall consider, is baking. In this practice, meat has generally a covering of paste, by which any considerable exhalation is prevented, and the reten- tion of the juices renders the meat more tender. In all cases, when the heat applied loosens, and in some measure extricates, the air without exhaling it, the substance submitted to this process is rendered more tender than when an exhalation is allowed. In broiling, an exhalation takes place, but as the heat of a naked fire is more nearly applied, the outer surface is in some measure hardened before the heat penetrates the whole, and thereby a great exhalation is prevented, while the whole is rendered sufficiently tender; but this kind of cookery is suited to meats that are chosen to be eaten a little raw. Nearly akin to this is the practice of frying, in which the meat being cut into thin slices, and laid in a pan over the naked fire, the heat is applied more equally to the whole substance. But as the part of the meat lying next to the bottom of the vessel would be suddenly hardened by the heat, it is always necessary to interpose some fluid matter, usually of an oily quality, as butter. A strong heat applied to the latter renders it empy- reumatic, or at least less miscible with the fluids of the stomach; so that all fried meats are less easily digested than those of any other preparation. Sometimes, indeed, the same thing hap- C O F. DICTION ARY OF C O P 195 MECHANICAL SCIENCE. pcns to baked meats, to which an oily matter, and that only, is added to avoid the too drying heat of the oven. It is obvious, that the preparations of stewing and frying may be frequently joined together ; and according to there being more or less of the one or other, the effects may be imagined.—WAtki Ns' CYCLOPOEDIA. : - COOLER, among brewers, distillers, &c. a large vessel wherein certain liquors are cooled after having been boiled. COOPER, in the Trades, an artificer who makes casks, tubs, barrels, and all kinds of wooden vessels, which are bound toge- ther with hoops. This is unquestionably a very ancient trade, and is referred to 2000 years ago by the writers on rural economy in Rome. Their descriptions correspond in a good measure with the construction of casks in our day. It is not known when the business of a cooper was first introduced into this country, but it has been supposed it was derived from the French. Wood used for the purpose of cask-making, should be old and thick; straight trees are the best; from these are hewn thin planks, which are formed into staves. In France, we are told, the wood is prepared in winter; the staves and bottoms are then formed, and they are put together in summer. CO-ORDINATES, in the theory of Curves, signifying any absciss, and its corresponding ordinate. * COPAIBA, or BALsAM of CoPAI BA, a liquid resinous juice, which comes from the trunk of the copaifera balsamum. Dis- tilled in water, it yields a quantity of limpid essential oil. COPAIFERA, a genus of the monogynia order in the decan- dria class of plants, ranking in the natural method under the doubtful order. There is only one species, the officinalis, which grows in Spanish America. Some trees do not yield any balsam, and those which do are distinguished by a ridge run- ning along their trunks. These trees are wounded in the centre, and one of them will yield five or six gallons of balsam, but though they thrive after being tapped, they never give any more Juice. * - COPAL, is a beautiful white resinous substance, with a slight tint of brown. It is sometimes opaque, and sometimes almost perfectly transparent. When heated, it melts like other resins; but it differs from them in not being soluble in alcohol, nor in oil of turpentinc without peculiar management. Neither does it dissolve in the fixed oils with the same ease as the other resins. When copal is dissolved in any volatile liquid, and spread thin upon wood, metal, paper, &c. so that the volatile menstruum may evaporate, the copal remains perfectly trans- parent, and forms one of the most beautiful and perfect warnishes that can well be conceived. The varnish thus formed is called copal warnish, from the chief ingredient in it. COPARCENARY, in Law, an estate is said to be so held when lands of inheritance descend from the ancestor to two or more persons. COPERNICAN System, is that system of the world in which the sun is supposed at rest; and the earth and the several plannets to revolve about him as a centre, while the moon and the other satellites revolve about their respective primaries in the same manner. The heavens and stars are here supposed at rest, and that diurnal motion which they appear to have from east to west is imputed to the earth's motion from west to east. This system was asserted and taught by many of the ancients, particularly by Egphantus, Seleucus, Aristarchus, Philolaus, Cleanthes, Samius, Nicetas, Heraclides, Ponticus, Plato, and Pythagoras; from the last of whom it was anciently denomi- nated the Pythagorean System. COPERNICUS, Nicolas, an eminent astronomer, born at Thorn in Prussia, Jan. 10, 1472, very early discovered a great bias for mathematics, which he pursued through all its various branches; and soon acquired so great a reputation, that he was chosen professor of mathematics at Rome, where he taught for a long time with great applause. He also made some astronomical observations there about the year 1500. Returning to his own country, he began to apply his knowledge to correct the system of astronomy which then prevailed. Of all the hypotheses of the ancients, none pleased him so well as the Pythagorean, which made the sun the centre of the system, and supposed the earth to move not only round the sun, but round its own axis also. After much profound contemplation, and many careful calculations, he removed the obscurities of making experiments. this old system, and, in fact, much improved it. His discove- ries and improvements he comprised in a book, printed in 1543, under the title of “Revolutionibus Orbium Coelestium;” and the author received a copy of it a few hours before his death, on the 24th of May 1543, he being then 70 years of age. Few works have destroyed more errors, or established more important truths, than this great work of Copernicus. His | noble theory was at first coldly received, or utterly rejected: but the labours of future astronomers at length obtained it a complete triumph. Corpernicus was also the first who demon- strated the double orbit of the moon; her menstrual motion about the earth, and her annual about the sun. Nor did this great man stop here: for, after laying a solid foundation of the celestial physics, he began the superstructure, by surmising a principle of attraction to be inherent in all matter. Copermicus also wrote a tract on Trigonometry; and has exhibited tokens of the versatility of his talents, as it is acknowledged that he had considerable skill as a painter, and was extremely well acquainted with the Latin and Greek languages. Copelt Nicus, the name of an astronomical instrument, invented by Whiston, to shew the motion and phenomena of the planets, both primary and secondary. COPPER, a well-known metal, orange-coloured, nine times heavier than water, and very elastic. This fine metal, of which Great Britain produces abundance, is manufactured into numerous kinds of utensils, machinery in powder mills, sash frames, and several preparations of medicine. The oxide or rust of copper gives a beautiful green to porcelain, or glass: hence it is employed in making artificial emeralds. Copper is very abundantly used in covering the bottoms of ships. It is nearly forty years since the more intelligent among our ship- owners introduced the use of copper as sheathing for their vessèls, and the advantages soon became so conspicuous, as to lead to its adoption in most cases where the circumstances of the owners were such as to admit of the expense. In the navy, the more general use of copper has formed one of the main features of the improvements of the age, but at a great expense, in consequence of the rapid decay of the article ; for while in a few cases copper would be found to last ten or fifteen years, in the great majority of instances it was worn out in a third, or less than a third, of the time. The Commis- sioners of the Navy, anxious to lessen this source of expense, and still more the uncertainty which attaches to the duration of vessels, particularly on foreign stations, from the decay of the copper, determined that a course of experiments should be instituted, to ascertain, if possible, the cause of this remarkable difference in the quality. Application was, therefore, made to Sir H. Davy, and the council of the Royal Society, for their assistance, also to the officers of his Majesty's Mint. At the Mint the investigation was undertaken by Mr. Mushet, who, from his situation in the melting department, had great advan- tages, both in experience, and in the command of machinery for He was also supplied with specimens of copper by the Navy Board, taken from the bottom of a Dutch ship, the Batavia, captured in the year 1798, the copper of which, after 25 years’ wear, was very perfect, though con- siderably reduced in weight. Mr. Mushet, after engaging in this important investigation, at last brought his labours to a satisfactory close, having arrived at a knowledge of the che- mical process by which durability is communicated to copper, and having taken out a patent for the newly discovered method. COPPERAS, the green salt sulphate of iron is so named; and also the blue salt sulphate of copper is sometimes also called copperas. COPPERED, or Copper-Bottomed, sheathed with thin sheets of copper, which prevents the worm eating into the planks, or filth accumulating on the bottom, whereby a ship is made to sail heavily. - - Copper-FAstened, the bolts and other metal work in the exterior of the bottom, made of copper instead of iron; the advantage of which is, that the vessel may afterwards be cop- pered without danger of the sheathing corroding the heads of the bolts, which it is found to do, if they are made of iron; and to prevent the rapid corrosion and decay of copper, on the bottoms of ships, Sir H. Davy recommends the fixing of small masses or wires of tin, or some other readily oxidable metal, I96 C O R C O R. DICTIONARY OF MECHANICAL SCIENCE. in contact with the copper sheathing, by which it is expected that the copper will be rendered so negatively electrical, that the sea water will act but slightly upon it. COPULA, in Logic, the verb which connects any terms in an affirmative or negative ; as riches make a man happy, where the word make is the copula. - COPULATIVE PRoportions, are those wherein the sub- ject and predicate are so joined by copulative conjunctions, that they may be severally affirmed or denied of one another. . . . COPYHOLD, in Law, a tenure for which the tenant has nothing to shew but the copy of the rolls made by the steward in the lord’s court.—The customs of manors differ as much as the humour and temper of the respective ancient lords; so a copyholder by custom may be tenant in fee-simple, in fee-tail, for life, by the courtesy, in dower, for years, at sufferance, or on condition; subject, however, to be deprived of these estates upon the concurrence of those circumstances which the will of the lords, promulged by immemorial custom, hath declared to be a forfeiture, or absolute determination, of those interests ; as in some manors the want of issue, in others the want of issue male, in others the cutting down timber, in others the non-payment of rent or fine. Yet none of these interests amount, to freehold ; for the freehold of the whole manor abides always with the lord only, who hath granted out the use of occupation, but not the corporeal seizin, or true possession of certain parts or parcels thereof, to these his customary tenants at will. If a person would devise a copyhold estate, he cannot do it by his will, but he must surrender to the use of his last will and testament, and in his will declare his intent; and here the lands do not pass by the will, but by the surren- der thus made. Copyhold inheritances have no collateral qualities, which do, not concern the descent, as to make them assets to bind the heir, or whereof the wife may be endowed, &c. They are not extendible in execution, but are within the acts against bankrupts, and the statutes of limitation. COPYRIGHT, the right which an author may be supposed to have in his own original literary compositions; so that no other person, without his leave, may publish or make profit of the said compositions. - CORACIAS, the Roller, a genus of birds of the order of pica, of which there are sixteen species, though some are only supposed to be varieties. . CORALLINA, or CoRAL, a genus belonging to the order of vermes zoophyta. . The species are distinguished by the form of their branches, and are found in the ocean attached to stones, bones, shells, &c. The corals were formerly believed to be vegetable substances, but are now known to be only a conge- ries of animals. The islands in the South Seas are mostly coral rocks covered over with earth. The little creatures, which have hardly sensation enough to distinguish them from plants, build up a rocky structure from the bottom of the sea, till it reaches the surface. Some of the coralline islands are much older than others, and it is probable, .that as these submarine . works are continually going on, new islands may be occasionally fifteen years old it is fit to be barked, and may be done suc- CORALLINES, in Natural History, were formerly reckoned plants, but, in the Linnaean system, are placed in the class produced. - zoophytae, and defined to be submarine plants, like bodies con- sisting of many slender finely divided and jointed branches, or animals growing in the form of plants, having their stems fixed to other bodies, which stems are composed of capillary tubes, whose extremities pass through a calcareous crust, and open into pores on the surface. The branches are often jointed, and always subdivided into smaller branches, which are either loose and unconnected, or jointed as if glued together. They are distinguished from plants by their texture, and hardness; they also yield in distiliation volatile salt, and their smell when turbid resembles that of horns, and other animal sub- stances. The corallines are distributed into the vesiculated, tubular, celliferous, and articulated winds. .. - CORALS, consist of nearly equal portions of carbonate of lime and animal matter. - - CORBEILS, in Fortification, are baskets filled with earth, and so placed on the parapet, or elsewhere, as to leave open- ings through which to fire upon the enemy without being discovered. . - - - * , . . . . . . . . ; CORD, MAGICAL, an instrument in great use among the Laplanders, and supposed to possess considerable virtues in certain magical rites and ceremonies. When properly pre- pared with knots, it is supposed to have power over the winds, and by means of it they will sell a favourable wind to any one If they untie that has faith enough to become a purchaser. . if two, only one of these knots, a moderate gale is to succeed; it is much stronger, and if three, there is to be a storm. CORDAGE, a general term for the running-rigging of a ship, as also for the rope which is kept in reserve to supply the place of such as may be rendered unserviceable. * . * CORDON, in Fortification; a row of stones made round on the outside, and set between the wall of the fortress, which lies aslope, and the parapet which stands perpendicular. CORDWAINERS, a term applied to the profession of shoe- makers, and by which they are incorporated. The word is formed from the French cordonnier, and that from cordovan, a kind of leather brought from Cordova in Spain. CORIANDRUM, Cori AND eſt, a genus of the digynia order in the pentandria class of plants, and in the natural method ranking under the 45th order umbellatae. There are only two species, both herbaceous annuals, the leaves of which are useful for culinary and the seeds for medicinal purposes. The leaves of both species resemble those of parsley ; but only one is cultivated, namely, the sativum, which has a small white fibrous root crowned by many parted leaves with broadish segments; in the centre is an upright branchy stalk, two feet high, having all the branches terminated by umbels of flowers, which are succeeded by globular fruit... It is propagated by seed sown in March. The seeds are carminative and stomachic. - • CORONA AUSTRALIS, the Southern Crown, is an asterism interwoven with Sagittarius, and appearing like a wreath of foliage round one of the fore legs of the fabulous Centaur. There are twelve small stars in this constellation. CORONA BOREALIS, the Northern Crown. This constel- 'lation-represents a beautiful crown given by Bacchus, it is said, to Ariadne, the daughter of Minos, second king of Crete. Bacchus, continues the fable, married Ariadne, after she was basely deserted by Theseus, king of Athens; and after her death, the crown that. Bacchus had given her, was made a constellation. This asterism was known to the Hebrews by the name of Ataroth, and by this name the stars in Corona Borealis are so called to this day in the East. - Boundaries and Contents.—This constellation lies between Boötes and Hercules, and is easily known by four stars, a, y, 3, s, forming a crescent. It contains 21 stars, of which a, called also Gemma, is of the 2d magnitude. Gemma rises N. E. by N. & E. and has 279 19' 39" of north declination, and 231°46’21" of right ascension. There are likewise six stars of the 4th magnitude, and the others are less in size. Meridian altitude of a, 65° 48' 39". . . CORK, is a substance analogous to wood; it is the exterior bark of a tree belonging to the genus oak, which grows wild in the southern parts of Europe. When the tree is fourteen or cessively for several years. The bark always grows up again, and its quality improves as the age of the tree, increases. If the bark, is not taken off in due time, it splits and peels off of itself, being pushed away by the second growth. The best bark comes from Spail, and Portugal; it is taken off in sheets, care being used in keeping them as large as possible. After it is detached from the tree the Portuguese burn or char it, laying the convex side of the bark to the fire, in order to straighten and swell it. It is then piled in stacks, ready for sale. • Cork is formed into soles for shoes, into corks; and bungs for stopping bottles, &c. into a floatage for the nets of fishermen; it is employed generally, though, perhaps with a considerable degree of error, in teaching the art of swimming; it is also . ingeniously used on account of its lightness, when an amputa- tion of the human leg has been necessary, to supply the defi- ciency. The Spaniards, line, stone walls with it, which not only renders their houses very warm, but corrects, the moisture of the air; the Egyptians made coffins of it, which being covered in the inside with a resinous composition, preserved their dead bodies. It is burnt, to make that light... black substance called Spanish black, from its having been first made in Spain. . Cork tº, O R. ‘C () R. DICTIONARY of MECHANICAL scIENCE. bark has not only been applied as above, but also in the pre- servation of life when in danger of shipwreck. . . . CoRk Fossil, a kind of stone which is a species of amianthus, Aconsisting of flexible fibres loosely interwoven, and resembling are qualified to take and grant, &c. cork. It is fusible by fire, and forms a black glass. . . . . . Cork Jacket, a sort of waistcoat composed of four pièces of . cork, two for the breasts and two for the back, the whole covered with canvass, with two holes to put the arms through. It was invented by Mr. Dubourg, but has been inproved by ...Dr. Wilkinson by cutting the cork into small pieces, and quilting them between two canvass waistcoats. The most timorous may venture, with one of these on, into a rough sea. CORN, the grain or seeds of plants separated from the It is contrary to the statute to buy or sell corn in the sheaf, or otherwise than by spica or ear, and used in making bread. : Winchester measure. CoRN, in Medicine or Surgery, a hard tubercle like a flat wart, growing in several parts of the feet, especially upon the This disorder is attributed to the wearing of joints of the toes. - - too straight or narrow-toed shoes, which never fail to produce ...these tubercles, especially if the person is obliged to stand or walk much, and in the summer time. Various are the methods used for removing these callosities of the skin and cuticle; some by the knife, and others by the application of emollient and caustic, or eroding medicine.—As few things are more troublesome than corns in the feet to those who have much walking, we may observe, that the pressure, may be prevented in the following manner: Take a piece of linen, spread with any emollient plaster; lay one piece over another, eight, or ten, or more times, and cut a hole in the middle of them, exactly the same size and circumference as the corn, then apply it in such a way that the corn enters the hole in the plaster, and it is thus defended against the contact of shoes and stockings. - CORNER STONES, in Architecture, the two stones which stand one in each joint of the chimney, commonly made of. Reigate or free-stone. * - 2- . CORNET, in the Military art, the third commissioned officer in a troop of horse or dragoons. He commands in the lieu- tenant’s absence, his principal duty being to carry the stand- ard near the middle of the first rank of the squadron. CokNet, among the Ancients, a musical instrument resem- bling a trumpet used in war. CORNUCOPIAE, or HoRN of PLeNTY, among Painters, &c. is a large horn, out of which issue fruits, flowers, &c. Upon models, the cornucopiae is given to all deities, genii, and heroes, to mark the felicity and abundance of all the wealth procured by the goodness of the former, or the care and valour of the latter. COROLLARY, a consequence drawn from advanced or demonstrated. CORONATION, the public and solemn confirming the title, and acknowledging the right of sovereignty belonging to a king or queen; at which time the prince swears reciprocally to the people, to observe the laws, customs, and privileges of the king- dom, and to act and do all things conformable thereto. CORONER, an ancient officer at the common law, and so called because he acts chiefly in pleas of the crown. . By sta- tute no person can be chosen coroner unless he have land in fee in the county. The electors also must be freeholders. The coroner's duty is to inquire how any person came by an untimely death, for which purpose he issues a precept to thc constables to return a competent number of persons to serve as a jury, which must consist of twelve at the least. He may commit, after inquisition, any person found guilty by the jury of murder or manslaughter, and may bind over the witnesses something to give evidence. It is also the duty of the coroner to inquire || of treasure that is found, who were the finders, and also who is - suspected thereof. By 25 George II, the coroner shall have 20s. and 9d, a mile for the distance he shall travel to take an inquisition, paid him out of the county rates. CORPORAL, an inferior officer in a company of foot, who has charge over one of the divisions, places and relieves senti- nels, and keeps order in the squad to which he belongs; he 'also receives the word from the inferior rounds, which pass by his corps-de-garde. This officer carries a fusee, and is colleges and hospitals, &c. the perfect and the imperfect. | is found in the East Indies, particularly in Peru and Ceylon; commonly an old soldier: there are generally thrée corporals in each company. . . . • . . . . . . . . . . . CORPORATION, a body politic or incorporate, so called because the persons or members are joined into one body, and Corporations are either spiritual or temporal : spiritual, as bishops, deans, archdeacons, parsons, vicars, &c.; temporal, as mayor, community, bailiffs, burgesses, &c. And some corporations are of a mixed nature, composed of spiritual and temporal persons, such as heads of All corporations are said to be ecclesiastical or lay : the former are either regular; as abbeys, priories, chapters, &c. or secular, as bishoprics, deaneries, archdeaconries, &c.; lay, as those of cities, towns, companies, p - , - . . . . º ...) or communities of commerce, &c. g Corporations may be established in three different ways, viz. by prescription, letters patent, or act of parliament; but they are most commonly established by patent or charter. The corporation of London is by prescription; but though corpora- tions may be by prescription, yet that prescription did originally derive its authority by a grant from the king. A corporation may be dissolved ; for it is created upon a trust, and if it be broken it is forfeited. No person shall bear office in any cor- poration but such as have received the sacrament, taken oaths, &c. and none are to execute in a corporation for more than a year. A corporation cannot sue or appear in person, but by an attorney. Ordinances made by corporations, to be observed on pain of imprisonment, forfeiture of goods, &c. are contrary to Magna Charta. Actions arising in any corporation may be tried in the corporation courts; but if they try actions not within their jurisdictions, and encroach upon the common law, they are liable to be punished for it. The corporation of the city of London is to answer for all particular misdemeanors committed in any of the courts of justice within the city, and for all other general misdemeanors committed in the city. . . CORPS, in Military affairs, means a body of soldiers. Corps de garde, is a post in an army sometimes under cover, or in the open air, to receive a number of men who are relieved from time to time. The term is also applied to the men who watch at the post. - CORPUS CUM CAUSA, in Law, a writ issuing out of the Chancery to remove the body and record into the King's Bench, there to lie till judgment shall be satisfied. . . . . . CORPUSCLE, in Physics, a minute particle or atom, of which natural bodies are formed. - * . . . . . CORRELATIVE, something opposed to another in a certain relation, as father and son, light and darkness, motion and rest. CORROSION, the action of gnawing away by degrees the continuity of the parts of bodies. - . . . . . CORROSIVE SUBLIMAte, the old name for the chloride of mercury, called also oxymuriate of mercury, and muriated mercury. - CORROSIVES, in Surgery, medicines that corrode whatever part of the body they are applied to, as burnt alum, white pre- cipitate of mercury, white vitriol, red precipitate of mercury, and lapis infernalis. - w CORRUPTION, the destruction of the existence of any natural body. : CoRRUPTIon of Blood, in Law, an infection accruing to a man’s state, attainted of felony and treason, and to his issue; proper mode of for as he loses all to the prince, &c. his issue cannot be heirs to him, or to any other ancestor by him; and if he were noble, his heirs are rendered ignoble. CORSELET, a little cuirass, or, according to others, an armour or coat made to cover the whole body, anciently worn by the pikemen usually placed in the front and flanks of the battle, for the better resisting the enemy’s assaults, and guarding the soldiers placed behind them. - - CORTEX, in Botany, the outer rind or bark of trees. CORUNDUM, a mineral, of which there are two species, Perfect corundum, or sapphire, and it is most commonly crystallized. The general colour is blue, sometimes without colour, others red, purple, yellow, and green. CORUS, a measure in Jewish antiquities, answering to the ‘omer, containing 75 gallons 5 pints for liquids, and 32 pecks 1 pint, dry measure. 3 E 198 C O T C O T DICTIONARY OF MECHANICAL SCIENCE. CORUSCATION, a gleam of light issuing from any thing. It is chiefly used for the electrical fluid, when it becomes ºisible, as the flash of lightning, &c. & CORVUS, the Crow, one of the old constellations, lies south of Virgo, north of Hydra, east of Crater, and west of Hydra Continua. This constellation is said to have its name from the crow into which Apollo metamorphosed himself when he escaped from the giant Typhaeus. Castor and Apollo were the same. Typhaeus and Typhon are the same. The Crow rises in the east, when the Twins come to the meridian. Typhon was a type of the lower hemisphere; the Crow then was the symbol of the Twins, having possession of the meridian. Corvus, the raven or crow kind, a genus of birds of the order of picae. There are 19 species, the principal of which are, 1. The corax or raven. 2. The corone or carrion crow, very much resembles the raven in form and habits. 3. The frugile- gus or rook, is the corvus of Virgil ; no other species of this kind being gregarious. 4. The cornix or Royston crow in its habits resembles the rook, feeding on insects, and flying in great flocks. 5. The dauricus, or white-breasted crow. 6. The monedula, or jackdaw, weighs about nine ounces. , 7. The glandarius, or jay, is one of the most beautiful of British birds. 8. The caryocatactes, or nut-cracker, is less than the jackdaw, the general colour of the body is of a rusty brown, and the wings are black, with white spots. These birds seldom visit England, but abound in Germany. 9. The pica, or magpie, in its manners approaches near to the crow, feeding both on animal and vegetable food. 10. The graculus, or red-legged crow, is of a slender make, active and thriving, much taken with glitter, and apt to catch up lighted Sticks, whereby it has been even known to set houses on fire. It is found in Corn- wall, North Wales, and Scotland. 11. The cristatus, or blue jay, is smaller than the common jay. This species is peculiar to North America. 12. The Canadensis is a small bird, the general colours of which are yellow-white, blackish-brown, and a pale ash. These birds inhabit Canada and Hudson's Bay, where they are called whiskijohn and whiskijack. CORYLUS, the Hazel, a genus of the polyandria order, in the monoecia class of plants; which in the natural method rañks under the 50th order, amentaceae. There are three spe- cies, all of the shrub kind, having several varieties, valuable for their nuts, and their usefulness in copses and hedges. The wood is useful for poles, hoops, spars, handles, fishing rods, &c. A kind of chocolate has been prepared of the kernels of the nuts; and the oil expressed from them is used by painters and chemists. - - COS, the Whetstone, a genus of vitrescent stones, of which there are several kinds, some consisting of rougher, and others of smoother particles; and used not only for whetstones, but also for mill-stones and other purposes. COS-TURCIA, Turkey Stone, a species of stones of the garnet kind, and of the siliceous class. It is of a dull white, and often of an unequal colour. It strikes fire with steel, and effervesces with acids. It is used as a whetstone, and those of the finest grain are the best hones for cutting tools, razors, lancets, &c. - - . COSMETIC, in Physic, any medicine or preparation which renders the skin soft and white, or helps to beautify and im- prove the complexion, as lip-salves, cold creams, ceruss, &c. COSMICAL, an astronomical term for one of the poetical risings of a star; thus a star is said to rise cosmically when it rises with the sun. COSMOGONY, the science of the formation of the uni- verse; or that which discusses the particulars of the creation of the world. COSMOGRAPHY, a description of the several parts of the visible world; or the art of delineating the several bodies, according to their magnitudes, motions, &c. two parts—geography and astronomy. . - COT, in Naval affairs, a particular sort of bed-frame, sus- pended from the beams of a ship, for the officers to sleep in. It is made of canvass, sewed in the form of a chest, about six feet long, one foot deep, and two or three wide, and is extended by a square wooden frame, with a canvass bottom, on which It consists of the bed or mattress is laid. It is reckoned much more con- venient at sea than either the hammocks or fixed cabins. Water Frame. COTTON is the produce of the gossypium, a plant about the size of a currant bush, a native of the torrid zone, though it is produced in parts of Turkey, so far as 44 or 45 degrees from the equator. The finest cotton is known by the name of cat's- claw, from its singular appearance when it breaks the pod. This kind was accidentally discovered at the island of Bour- bon, and was supposed to have been introduced among some seed sent from South America to the Mauritius. The soil should be extremely well prepared, and of the best quality, for the reception of cotton seed, which is usually sown in Novem- ber or December, after the periodical rains in tropical climates, and ripens in May or June; when the numerous pods, which are about the size of large gooseberries, break, and display their downy contents. These are picked, and after the husks have been disengaged, the cotton is put into a small mill, consisting of two bright steel rollers, each about an inch in diameter, set parallel within the distance of about the 20th part of an inch. These rollers move different ways, and draw the cotton through between them, while the seeds are forced out of the respective little balls of down in which they are enclosed, and drop into a bag. The generality of cotton is white; but some is of a man- keen colour, and is invaluable in the manufacture of that article, as it fades very little, even with long use and frequent washing. The elasticity of cotton is inconceivable ! It may be pressed into a 50th part of the space into which the strongest packers can reduce it by personal exertion: large screws are erected at many sea-ports where cotton is shipped, for the purpose of bringing the bales into the smallest compass, so as to save freight. Cotton can only be imported as a raw mate- rial, in which form it comes to us from the Levant, the West Indies, America, and the East Indies. In the last quarter, there are some kinds indigenous, but some are exotics. It is a highly dangerous cargo, being very subject to take fire if at all damp when packed, or if the smallest spark should reach it; in either case, it will burn very slowly for weeks; but when the hold is opened, and air supplied, bursts forth with inconceiv- able fury. There is a species of silky down produced in pods, (similar to those of the cotton plant,) on a very large tree, called the seemul. It is only fit to fill beds. Specimens of it have passed through various hands; but this kind of cotton is so peculiarly glossy, and the fibre so short, that it could neither be carded nor spun. When mixed with rabbit's fur, &c. to make hats, it is always separated. It also ſailed in paper- making; otherwise its abundance and cheapness would have rendered it highly important. Cotto N Manufacture, in Commerce, is now one of the most important branches of British industry. Cotton Spinning, the process of reducing cotton wool into yarn or thread. The method formerly used for this purpose was by the hand, upon a machine called a one-thread wheel. But about 1767, Mr. Hargrave, an operative weaver of Lancashire, made a machine, by which a great number of threads might be spun at once, and for which he obtained a patent. This is called a jenny, and with it, one person can spin 100 hanks in a day; each hank containing 840 yards. . - Carding of Cotton, as a preparation for spinning, used for- merly to be performed by the hand, with a single pair of cards on the knee, but this being a tedious method, and ill adapted to the rapid operations of the spinning machines, new ways were contrived. The first improvement was by Mr. Hargrave, and consisted in applying two or three cards to the same board, and fixing them to a stool or stock; with these, one woman could perform three times as much as by the common way. But a more expeditious method is by the cylinder cards, to the invention of which several persons lay claim. The next great improvements in the cotton manufacture were from Mr. (after- ward Sir Richard) Arkwright, of Cromford, in Derbyshire. He obtained a patent for his new system of spinning cotton in 1769, and in 1775 another, for engines to prepare the materials for spinning. The validity of this second patent was set aside in 1781, but in 1785 he obtained a verdict that established the sufficiency of his patent. In the same year, however, he was castin another trial, on the ground of his not being the original inventor of that simple and beautiful contrivance the Twist or Arkwright still persevered in declaring himself the inventor, and on the 10th of November, 1785, he moved, in C O T C O T DICTIONARY OF MECHANICAL SCIENCE. the court of King’s Bench, for a new trial; but his rule was refused ; and on the 14th of November, 1785, the court of . King's Bench gave judgment to cancel the letters patent. It may be proper to observe, that Sir R. Arkwright's contests with the rival manufacturers of Lancashire, related chiefly to the operation of carding. The Annual Register for the years 1781 and 1785, or the Gentleman's Magazine, probably contains faithful records of all these trials, rules, and issues. - . . The result of Arkwright's inventions is a combination of machinery, by which cotton is carded, wove, and spun with the utmost exactness. To these improvements, the country is indebted for the great extent of its cotton manufactures; large works having been erected in England and Scotland, many containing several thousand spindles, driven by large water- wheels, some of such extent as to spin at the rate of 1000 yards of twist in a minute. Another machine has been invented, called a mule, because it is a kind between Mr. Hargrave's and Mr. Arkwright's. This also promises to be of great use in spinning cotton yarn for muslims to a degree of fineness equal to those of India. See MILL. The operations which cotton undergoes in its passage from the raw material to the state of thread, are various and multi- plied in proportion to the fineness required, and the different uses to which it is destined. If we analyze these operations, they resolve themselves into the following: Batting, carding, doubling, drawing, and twisting. The three latter are never performed singly, but are variously joined in the same machine; and the same elementary processes are oftentimes repeated in different machines, with various and different effects. With reference to these effects, the operations which cotton under- goes, may be denominated batting, carding, drawing, and doubling, roving, and spinning. Batting, is that operation which prepares the cotton for card- ing, by opening and disengaging the hard compressed masses in which it comes from the bales. It is performed by beating the cotton with sticks on a square frame, across which are stretched small cords, about the thickness of a goose quill, with intervals sufficient to suffer the seed, leaves, and other adven- titious matter, to fall through. When a hard matted or com- pressed mass of cotton is smartly struck with a stick, the natural elasticity and resiliency of its fibres, gradually loosen and disengage them, and the cotton recovers by repeated strokes all its original volume. During this operation the seeds, &c. which adhere, are carefully picked out by the hand, and the cotton rendered as clean as possible. Batting is gene- rally and best performed by hand, though the scarcity of hands and cost of labour have rendered other contrivances necessary. Carding, is that operation in which the first rudiments of the thread are formed. It is performed, as we have before stated, by cylinders covered with wire cards, revolving with consider- able swiftness in opposite directions, nearly in contact with each other, or under a kind of dome or covering, the under surface of which is covered with similar cards, whose teeth are inclined in a direction opposite to those of the cylinder. By this means the separation of almost every individual fibre is effected, every little knotty or entangled part disengaged, and the cotton spread lightly and evenly over the whole surface of the last or finishing cylinder, from which it is stripped by the contrivance we have already described. For jenney spinning, which is still in use for the coarser kinds of thread, the cardings are stripped off in separate lengths. The finishing cylinder is covered with the ordinary cards nailed on in stripes across, and the cotton contained between the margins or intervals of each stripe, forms one carding, whose length of course depends on the width of the engine, or cylinder. When stripped off by the crank and comb, { it forms a loose and shapeless film, which falling on the sur- face of a plain wooden cylinder, the lower half of which revolves within a hollow shell or casing, the cotton in its passage is rolled up and delivered at the other side in perfect and cylin- drical cardings. For mule or water spinning, the finishing cylinder is covered with spiral or fillet cards, and the cotton being taken offin one continued fleece, and contracted by passing through the funnel and rollers, forms one endless and perpetual carding, which is interrupted only, or broken, when the tin can that receives it is completely filled. In the jenney carding, the fibres of the cotton are disposed across or at right angles to the axis of the carding; in the per- petual carding they are disposed longitudinally, or in the direc- tion of its length, and it is this circumstance which renders the carding destined for mule or water spinning, inapplicable to the jenney, and vice versá. Drawing, and Doubling, is one of the preparatory processes for which we are indebted wholly to Sir Richard Arkwright, and belongs exclusively to the mule, or water spinning. The doubling, or passing three or four cardings at once through a System of rollers, by which they are made to coalesce, is in- tended to correct any inequalities in the thickness of the card- ings, and also to admit of their being frequently drawn out or extended by passing through the rollers. The effect of this frequent drawing is to dispose the fibres of the cotton longi- tudinally, and in the most perfect state of parallelism. The operation of carding effects this in a certain degree; yet the fibres, though parallel, are not straight but doubled, as may easily be supposed from the teeth of the cards catching the fibres sometimes in the middle, which become hooked or fastened upon them. Their disposition is also farther disturbed by the taker-off or comb, which strips them from the finishing cylinder; and though the general arrangement of the fibres of a carding is longitudinal, yet they are doubled, bent, and inter- laced in such a way, as to render the operation we are now speaking of absolutely necessary. When the cardings have been passed four or five times through the drawing frame, every fibre is stretched out at full length, and disposed in the most even and regular direction; and though the average length of a fibre of cotton is not two inches, yet the finished drawing, as these prepared cardings are now termed, has all the appearance of a lock of Jersey wool, whose fibres, six or eight times as long as those of cotton, have been carefully and smoothly combed. - Roving, is that operation by which the prepared cotton, as it comes from the carding engine, or drawing frame, is twisted into a loose and thick thread, and wound upon a spindle or bobbin. In jenney spinning, the cardings are roved without any other preparation, by a machine called a roving billy; for a descrip- tion of which, with other particulars relative to jenney spin- ning, see JENNEY. - In mule or twist spinning, the prepared carding or drawing, as it is termed, is again passed through a system of rollers, and is twisted, either by a rapidly revolving can, into which it is delivered from the rollers, or by a fly and spindle similar to those of the flax wheel ; in the latter case it is wound on the bobbin by the machine; in the former, it is received in the conical can in which it acquires the twist, and is afterwards wound upon bobbins by the smaller children of the mill. Sir Richard Arkwright always employed the revolving can, and it is still employed in many of the first mills in the country, The roving frame with fly and spindle, which is in fact nothing more than the twist frame of Sir Richard, is now however very generally in use, especially since later improvements have removed objections to the machine, which rendered its use heretofore inconvenient. See FRAME. The operations through which the thread passes after it has received the first twist are various, and depend greatly on the use it is intended for. The finer it is required, the oftener it is drawn out and twisted, till by degrees, as in the process of wire-drawing, it is brought down to the fineness required. The rowings are therefore distinguished into first, second, and third, according to the number of operations they have gone through. Spinning, is the last operation which the thread undergoes in the series of processes employed in converting it into thread, and is that in which it receives the final extension and twist- ing. It is performed either on the jenney, twist frame, or mule. The thread is of two kinds, viz. twist, so called from its being harder twisted than the other, forming a stouter thread, and used for the web or warp of piece goods; and weft, which is a looser, softer thread, and used for the woof. The weft is delivered to the weaver in small oblong rolls called cops, in the state they are stripped off the spindles of the mule or 200 G O T T; ) T ... DIGTi () NARY QF MECHANICAL SCIENCE. jenney. When these are used, a smaali pointed piece of wood or skewer is carefully passed through the axis of the cop into the place formerly occupied by the spindle, and one end of it being held between the teeth, the thread is wound off the cop upon the weaver's bobbin by a wheel somewhat smaller in size, but the same in principle as the common one-thread wheel, on swhich all the spinning was formerly performed. This is gene- rally done by children, and the bobbins are then ready for the shuttle. Twist undergoes several operations before it is ready : for the loom. It is delivered by the spinner either in hank or : - - - | evenly one way, and firmly glued fast to the thread. - CO Hank twist is that which is spun on the water frame, from § the bobbins of which it is reeled into hanks of a determinate length, each measuring 840 yards....The value and fineness of the thread are proportionate to the number of hanks in a pound, and they are denominated by numbers, as Nos. 20, 50, 100, &c. which express, the hanks which a pound of twist contains. In this state it is generally sized, an operation which is intended to give additional strength and tenacity to the thread, and enable it to support the different operations in its passage to the loom. thin size, chiefly formed of wheat flour boiled in water, with the addition of a little glue. The twist is carefully worked in this, and afterwards wrung and dried. The thread acquires con- siderable strength by this operation, and the loose fibres are all firmly attached or glued to its surface. It is then delivered to the winder. - - ‘. . - - Winding, is that operation by which the thread is transferred to the warping bobbin, either from the cop, hank, or twist frame bobbin. - . . " It consists in impregnating the thread fully with Formerly this was chiefly done by females, and the work was carried home and performed by any of the family not engaged in domestic concerns, on a small wheel that turned two bobbins at a time. This mode is still in use, but the work has been greatly abridged and facilitated by the use of machines of - | to enter the shuttle. various constructions. Cop twist is that which is spun on the mule or jenney. It is | mon bobbin. . In those large establishments where the different reeled only occasionally, to ascertain its value and fineness, and is delivered in cops to the winder. . . . . - The next operation is that of warping, or the formation of +he web. The machine on which this is performed is an octa- gonal prism five or six feet high, and somewhat less in diame- ter, revolving vertically, and put in motion by a band and pulley placed under the seat of the warper. The bobbins which furnish the thread are suspended horizontally in a frame on one side. Twenty-eight or thirty threads, forming together a system called a half beer, are wound round the prism in a spiral form from top to bottom. The machine is then turned the contrary way, and the thread wound round the prism up- wards from bottom to top, and this is repeated backwards and forwards till a sufficient number of half beers have been wound to form a web of the breadth required. When finished, and the ends properly secured, the whole is wound off and coiled upon the hand into a round ball called the warp. If the thread has been previously sized in the hank, it is now ready for the loom, but if the warp is made of cop twist, that operation is next performed. - The warps are boiled several hours in water till they are thoroughly penetrated and softened; after draining some time they are then uncoiled and worked in the size till fully impreg- nated, after which the superfluous size is squeezed out, and they are suspended on poles to dry : the warp is then ready for the loom. - - Without this operation of sizing, which, as we have before observed, gives strength and tenacity to the thread, it would not support the friction of the loom. Two threads are passed between each dent of the reed, and at each stroke of the treadle one ascends whilst the other descends. There is there- fore a constant friction of the threads upon each other, as well as against the teeth of the reed. The motion of the reed itself also backwards and forwards, and of the healds up and down, is very severe upon the warp, and unless it has been well penetrated by the size, and its fibres well cemented or glued together, this continual rubbing is sufficient to destroy its still further aided by feXture. Good sizing prevents, this, but it is another operation called dressing, which is: performed by the weaver himself, after the warp. is got into the loom. : This con- sists first, in applying with a brush a kind of paste made of wheat flour well boiled, to which is often added a small portion of common salt; sometimes of potash, and sometimes even a little tallow. It is in fact a repetition of the operation of siz- ing, with this difference, that the dressing is applied chiefly to the surface of the thread, which is slightly sméared with the paste, and brushed uniformly iſ one direction' from the healds d to the beam, by which means the loose fibres are all disposed In summer the warp is dried simply by fanning it, but in winter, and in damp cold weather, a hot iron is lightly passed over it. It is then dressed again with a brush dipped in tallow or butter, with which it is slightly greased. This gives suppleness and smoothness to the thread, and greatly dimin- ishes the friction of the healds and reed. As such a portion of the warp as is extended between the healds and beam can alone be dressed at one time, this is woven, and the dressing repeated again upon another portion, and so on, alternately dressing and weaving till the whole of the web is finished. Various improvements on these different processes have taken place of late years, which have made greater or less progress in proportion to their utility and importance. We shall enumerate, therefore, not only those of recent date, but such as, though known some time, have not been generfilly adopted. - - " - - - - The weaver's bobbin is still wound by hand in the manner already described, though the use of a small machine, by | which twenty bobbins or upwards are wound at once, is daily gaining ground. They are to be seen now in almost every weaver's cottage where several looms are employed. This labour is further abridged by a very ingenious contrivance, for which a patent has been obtained. The cops, instead of being wound, are compressed or squeezed till they are small enough The winding here is done away, and the cops thus compressed are preferred by the weavers to the com- processes, such as spinning and, weaving, are carried on toge- ther, the cops are spun small enough to enter the shuttle with- out compression. The weft is transferred at once from the spindle of the mule to the weaver’s shuttle, and the time and waste of winding, and even of compressing, saved entirely. On the same principle also, a considerable reduction has been made in the labour of reeling and winding twist. Till within a late period, the practice has uniformly been to reel it into hanks from the bobbin it was spun on, to size it in the | hank, and then wind it for warping. An obvious reduction of this labour is to warp it directly from the bobbin it is spun on, and size it in the warp like cop twist. For reasons, however, which it will not be necessary here to enter into, this has been found impracticable. It is, however, transferred to the warp- ing bobbin, without the intermediate labour and waste of reeling, and the sizing is done in the warp. Considerable im- provements in the mode of sizing have been made within these few years, especially in the sizing of warps. . Formerly, the practice was to work the warp in the warm size by the hand, the heat of which was of course limited to that degree which could be readily borne by the workman. Experience having proved, that the hotter the size, the more evenly and perfectly was the warp penetrated, various con- trivances were adopted for applying it at a high temperature. Amongst others, are oblong troughs furnished with several pairs of rollers, through which the warp passes, and is strongly compressed whilst immersed in the hot size. Mr. Marsland’s idea of placing the twist in an exhausted receiver, and admit- ting the hot size, promises considerable advantages in some cases, and when the plan has been matured, will no doubt be susceptible of many applications. - But the greatest improvement that has been made in these different processes, and one that must eventually effect a com- plete revolution in the whole system, is Messrs. Ratcliffe and Ross's mode of dressing. Hitherto this operation has been performed by the weaver in the manner we have already de- scribed, at the expense of one-third of his time and labour. As it is only possible for him to dress at once as much of the work C O U C O U DICTIONARY OF MECHANICAL SCIENCE. 201 as is contained between the healds and beam, he is scarcely got settled to his work, after each operation, before he is again called off to dress another portion. By this continual inter- ruption of one species of labour by another totally different, it must be obvious to every one, that not only much time is lost, but that the labour itself cannot be equally well performed. There is a delicacy and certainty of touch in weaving, de- pendent on long habit and experience, and on which the even- mess and goodness of the cloth depends. If the force with which the woof or weft is driven up by the reed, be not always alike, if it is greater at one time and less at another, the cloth will be thicker and thinner at those places, and such is the nicety on which this depends, that the most experienced weaver, after an interruption of some hours, cannot at once regain it. z Messrs. Ratcliffe and Ross dress the whole of the warp before it is wound upon the beam, the labour of the weaver is therefore uninterrupted, and his attention directed solely to one object. This alone is a great point gained, but it is attended also by other, not less important, advantages. Great part of the intellectual skill required in weaving is in the dress- ing and beaming of the warp; the mere mechanical part of throwing the shuttle, &c. is soon acquired, even by a boy. A more accurate division of labour, by reducing the beaming and dressing to a system by which they are better, more economi- cally, and more expeditiously performed than before, has removed the great difficulty in the art of weaving, and rendered it in a great measure the employment of children. From what we have already said, it will appear that the object in dressing and sizing is nearly the same, and Messrs. Ratcliffe and Ross, by this improved mode of dressing, have succeeded in reducing these operations to one. They have gone still further; they have done away the necessity of warp- ing, by forming the web at once from the bobbin, and thus reduced the warping, sizing, dressing, and beaming, to one operation. A thousand bobbins and upwards supply the mate- rials for the warp, which in its progress is properly disposed and arranged, sized, dressed, and finally wound upon the beam. This improvement, which may justly be regarded as the most important that has taken place in weaving, since the invention of the fly shuttle fifty years ago, must in the end effect a complete change in the system of labour. Great how- ever as its advantages are, some time must necessarily elapse before it can be accommodated to general use. In large esta- blishments, where the different processes of the manufacture are carried on together, such as spinning, weaving, and the labour immediately connected with them, it has been adopted with the happiest success, but the weaving in this country is chiefly done in the cottages of the poor, and to their use the costly and bulky apparatus of Messrs. Ratcliffe and Ross is not adapted. To derive all the advantages possible from this improve- ment, therefore, it will be necessary either that the weaving be done in large shops, to each of which a dressing machine may be attached, or that the warps be delivered to the country weavers ready dressed and wound upon the beam. The former plan is daily gaining ground, and perhaps it is not difficult to foresee, that at no very distant period all the weav- ing of the country will share the fate of the spinning, and quit the cottage for those larger establishments in which it will be susceptible of better management, and more accurate division of labour. - * The last improvement, which we shall notice in the manufac- ture of cotton, and which, when once established, will com- plete what Arkwright has so happily begun, is that of weaving by machinery. Various attempts have been made of late years to apply the great moving powers, steam and water, to the common loom. See Loom. - COUCH, or CoAT, in Painting, a term for each lay of colour, either in oil or water, with which the artist covers his canvass, wall, wainscot, or other matter, to be painted. COUCHING, in Surgery, the operation of removing a cata- ºlish is done by a peculiar needle, called the couching • Ineedle. COULTER, in Husbandry, an Iron instrument fixed in the beam of a plough, and serving to cut the edge of each furrow. COUNCIL. In this country, the law, in order to assist the king in the discharge of his duties, the maintenance of his dignity, and the exertion of his prerogative, hath assigned him a diversity of counsellors with whom he may advise. 1. The first of these is the high court of parliament. 2. The peers of the realm are, by their birth, hereditary counsellors of the crown. 3. A third council belonging to the king, are, according to Sir Edward Coke, his judges of the courts of law, for law mat- ters. And this appears frequently in the English statutes, particularly 14 Edward III. c. 5, and in other books of law. So that when the king's council is mentioned generally, it must be defined, particularized, and understood, according to the subject matter; and if the subject be of a legal nature, then by the king’s council is understood his council for matters of law; namely, his judges. 4. But the principal council belonging to the king is his privy council, which is generally, by way of eminence, called The Council, composed of eminent persons, the number of whom is at the sovereign's pleasure, who are bound, by oath, to advise the king, to the best of their judgment, with all the fidelity and secrecy that becomes their station. The king may declare to, or conceal from, his privy council whatever he thinks fit, and has a select council out of their number, commonly called the cabinet council, with whom his majesty determines such mat- ters as are most important, and require the utmost secrecy. All proclamations from the king and the privy council ought to be grounded on law, otherwise they are not binding to the sub- ject. Privy counsellors, though but gentlemen, have precedence of all the knights and younger sons of barons and viscounts, and are styled right honourable. e & Council, Common, in the city of London, a court in which are made all by-laws which bind the citizens. It consists, like the parliament, of two houses, an upper, composed of the lord mayor and aldermen ; and a lower, composed of a number of common councilmen chosen by the several wards, as repre- sentatives of the body of the citizens. COUNSELLOR AT LAw, a person retained by a client to plead his cause in a court of judicature. There are two degrees of counsel, viz. barristers and serjeants. Barristers are called to the bar fter a certain period of standing in the inns of court. After 16 years’ standing, they may be called to the degree of serjeant. The judges of the courts of Westminster Hall are always admitted serjeants before they are advanced to the bench. From both serjeants and barristers the king’s counsel are usually selected, the two principal of whom are the attorney and solicitor-general. Counsel are supposed to plead gratis, and can maintain no action for their fees; and to encourage in them a freedom of speech in the lawful defence of their clients, a counsellor is not answerable for any matter by him spoken, though it should prove groundless, and reflect on the reputation of another, provided it relates to the cause which he espouses, and is suggested in his client’s instructions. And notwith- standing counsellors have a special privilege to practise the law, yet they are punishable for misbehaviour by attachment. No counsel is allowed to a prisoner upon a general issue of indictment of felony, unless some point of law arise; for the court is the prisoner's only counsel. COUNT, originally, a nobleman who possessed a domain erected into a county. The dignity is a medium between that of a duke and a baron. It is now merely a title of honour. Count, in Law, is the original declaration of complaint in a real action, as a declaration is in a personal one. COUNTER APPROACHES, in Fortification, lines and trenches made by the besieged to attack the works of the besiegers, or to hinder their progress. The line of counter approach is a trench made by the besieged from their covered way to the right and left of the attacks, in order to scour the enemy’s works. COUNTER BATTERY, is one raised to play upon another to dismount its guns. COUNTER-GUARD, in Fortification, a work raised before the point of a bastion. - COUNTERMARCH, a change of the face or wings of a bat. talion, whereby those that were in the front come in the rear. Also the returning or marching back again. 3 F 303 C. R. A.' G R. A DiGTIONARY OF MECHANICAL SCIENCE. COUNTERMINE, in War, a well and gallery driven and sunk till it meets the enemy's mine, to prevent its effects. - COUNTERPART, in Music, denotes that one part is to be applied to another. Thus the bass is said to be the counter- part to the treble. In Law, it is the duplicate or copy of an indenture or deed. COUNTERPOINT, in Music, the combining and modulating consonant sounds. . . . . . . - - COUNTERPOISE, any weight which, placed in opposition to another weight, produces an equilibrium, but it is more commonly used to denote the weight used in the Roman balance or steelyard. - of COUNTERSCARP, in Fortification, the exterior slope the ditch, though it is often taken for the covered way and glacis. Angle of the Counterscarp, is that made by its two sides meeting before the middle of the curtain. COUNTERTENOR, in Music, high tenor; a term applied to the highest natural male voice. - COUNT-WHEEL, in the striking part of a clock, is that which moves round once in 12 or 24 hours. - COUP-DE-MAIN, in Military aſſairs, implies a desperate resolution in small expeditions of surprise; or the attacking a place sword in hand. - COUPURE, in Fortification, passages sometimes cut through the glacis, of about twelve or fifteen feet broad, in the re-enter- ing angle of the covert way, to facilitate the sallies of the besieged. - - COURSE, in Navigation, the point of the compass, or hori- zon, which the ship steers on, or the angle which the rhumb line on which it sails makes with the meridian ; and is sometimes reckoned in degrees, and sometimes in points and quarter points of the compass. COURSING, among sportsmen, is of three sorts, viz. at the deer, at the hare, and at the fox. These coursings are with greyhounds; for the deer there are two sorts of coursings, the one with the paddock, the other either in the forest or purlieu. COURT, a place for the administration of justice. The most general division of our courts is into those of record, and those which are not; those of record are divided into supreme and superior or inferior. The supreme court of this kingdom is the high court of parliament, which has an absolute power to make new laws, and to repeal and alter old ones. Superior courts of record are the House of Lords, the Chancery, King’s Bench, Common Pleas, and Exchequer; the less principal are those held by commission of gaol delivery, oyer and terminer, assize, nisi prius, &c. The inferior courts of record are cor- poration courts, courts leet, the sheriff's torn, &c. Courts not of record are the courts baron, county courts, hundred courts, &c.; also the admiralty, and ecclesiastical courts, which derive their authority from the crown, and are subject to the control of the king's temporal courts, if they exceed their jurisdiction. COURT BARON, a court held by every lord of a manor within the same ; and if the number of suitors should so fail as not to leave enough to make a jury or homage, that is, two tenants at least, the manor is lost. This court may inquire of the death of tenants, of nuisances, waste, trespass, forfeitures, &c. and the punishment is by amercement. COURT OF CONSCIENCE, in the cities of London, West- minster, and some other places, determines matters in all cases, where the debt or damage is under forty shillings. In some places these courts have power to decide on larger sums. COVENANT, in Law, the agreement or consent of two or more, by deed in writing, sealed and delivered; whereby either, or one of the parties, promises to the other, that something is done already, or shall be performed afterwards. COVERT-WAY, or CoRRIDoR, in Fortification, a space of ground, level with the field, on the edge of the ditch, three or four fathoms broad, ranging round the half-moons, and other | works toward the country. COVERTURE, in Law, a term applied to a married woman who is under the power of her husband, and therefore incapable of making bargains to the injury of herself or her husband. COVIN, in Law, a deceitful assent or agreement between two or more, to the prejudice of another. - CRAB, a wooden pillar, somewhat resembling a small cap- stan, but not furnished with a drum head; instead of which, . k ke two, three, or four holes are made one above another, through: the middle of its upper end, into which long bars are thrust,. whose length is nearly equal to the breadth of the deck. . It is: employed for the same purposes as the capstan, but not being so convenient, is now generally laid aside, except in rope- walks, &c. The Crab, a machine with three claws, is used. to launch ships, and to heave them into the dock, or off the key. See CANCER, for the Celestial Crab. CRADLE, a frame placed under the bottom of a ship, in order to conduct her steadily and smoothly into the water when she is to be launched, at which time it supports her weight while she slides down the descent or sloping passage, called the Ways, which are for this purpose daubed with soap' or tallow. Cradles are also standing bedsteads made up for the wounded seamen, that they may be more comfortable than it is possible to be in a hammock. —Chidren's wicker cradles need hardly be alluded to ; nor does the more fashionable rock- ing or swing cot require illustration, except to observe, that the principle of suspension is capable of great improvement upon a very simple plan, that of the pendulum, in place of the clumsy method of hanging the cot on a tawdry brass knob, by a piece of wire bent in the form of an equilateral triangle. CRAFT, a general name for all sorts of vessels employed to load or discharge merchant ships, or to carry alongside, or return the guns, stores, or provisions of a man-of-war; such are lighters, hoys, barges, &c. CRAMBE, Sea Cabbage, Sea Beach Kale, or Sea Colewort, a genus of the siliquosa order, in the tetradynamia class of plants, ranking in the natural method under the 39th order siliquosae. There are six species, three herbaceous esculents with peren- nial roots, producing annually large leaves like those of the cabbage, spreading on the ground with yellow flowers. Only one species is a native of Britain, and it grows wild in several parts of the sea-coast. It is propagated by seeds sown in com- mon light earth in autumn or spring. The crambe fruticosa is a greenhouse plant. - CRAMP, in Medicine, a convulsive contraction of a muscu- lar part of the body, being either natural, as in convulsive con- stitutions, or accidental, from living in cold places, under ground, &c. It affects all parts indifferently, but the ham, calves, feet, and toes, oftener than the arms and hands. An effectual preventive for cramp in the calves of the legs, which is a most grievous pain, is to stretch out the heel of the leg as far as possible, at the same time drawing up the toes to the body. This will frequently stop the progress of a fit of the cramp after it has commenced; and a person will, after a few times, be able in general to prevent the fit coming on, though its approach be between sleep and waking. CRANE, THE, a machine used in building, on wharfs, and in warehouses, for raising and lowering huge stones, ponderous. weights, packages, bales of goods, &c. has been variously. constructed, and will therefore require a few examples. - The Cellar Crane we have already noticed. The Portable. Stone Crane for Loading and Unloading Carts, is mounted on a l | wooden stage, and is so constructed that it may be taken to pieces. The frame A, A, A, A, is about 10 feet high and 9 feet C. R. A CºR A DICTIONARY OF MECHANICAL sqLENCE. square; the wheels B, B, are of iron, and 3 feet diameter; the pinion D fixed to the axis of the first wheel B is 8 inches in diameter; and the other pinion C is about the same diameter. When stones are suspended to the rope that coils, round the barrel, the labourer turns a winch on the axis of the wheel C, and raises or lowers the weight according to the direction in which he turns it. - - - - Gottlieb's Carriage Crane.—This machine, which is useful for carrying large stones where carts and horses cannot be easily obtained, consists of two sorts of crane wheels applied to the #4. A Aſ ſº - *T. s ſº ºr #E §: º ####2. Y-Kºsſº two sets of wheels belonging to the carriage, so that two men, one acting at each winch A, A, give motion to the loaded car- riage. The pinion B, 6 inches in diameter, turns the wheel C, 3 feet in diameter. The wheel C gives motion to the pinion D, one foot in diameter, which works into two wheels E, E, 3 feet 6 inches diameter, and are fixed on the wheels of the carriage. Andrew’s Weighing Crane, weighs the body at the time that it raises it. The weight W is elevated by means of the levers M, H, O, N, which coils the rope T R round the barrel P. The ºv jib E D stands on a horizontal beam, moveable in a vertical tº-1 ET |TFE- s = Mr. Hº #. 22 D & # O ; : | Sák—#-Hº §lkº, ; k== ,-- ~~~~------ <ſº-º-º-m-ºrºr" F-ºff ; | {{|{ Él § ww. § plane round the centre FA, and the distance of the upright | beam E from the centre of motion A, is 3 of B F. The weight of the bulk W is then ascertained by the weight at B, which keeps it in equilibrio. The piece of wood C projects from the vertical beam C. L., in order to prevent the beam from rising too high. - - Ferguson's Crane has three trundles, with different numbers of staves, that may be applied to the cogs of a horizontal wheel with an upright axle; round which is coiled the rope that draws up the weight. This wheel has 96 cogs; the largest trundle 24 staves, the next 12, and the smallest 6, so that the largest revolves 4 times for one revolution of the wheel; the next 8, and the smallest 16. A winch is occasionally fixed on the axis of either of these trundles, for turning it; and is applied to the one or the other according as the weight to be raised is smaller or larger. While this is drawing up, the ratch-teeth of a wheel slip round below a catch that falls into them, prevents the crane from turning backwards, and detains the weight in any part of its ascent, if the man who works at the winch should accidentally quit his hold, or wish to rest himself before the weight is completely raised. Making a due allowance for friction, a man may raise by such a crane from three times to twelve times as much in weight as would balance his effort at the winch ; viz. from 90 to 360 lbs. taking the average labour. Bramah's Jib for Cranes.—The nature of this invention may be easily understood from a bare inspection of the figure, which represents a jib attached to the wall of a warehouse. The jib turns on a perforated axis or pillar. The rope by which the weight is raised, after passing over two pulleys, goes through the perforated axis, and is conducted over another . . . . . . pulley to the barrel of the efame, . which is not represented in the figure. In jibs of the commoa construction, which turn in two solid gudgeons, the rope passes over the upper gudgeon; and is confined between two vertical rollers; but the bending of the rope occasions a great deal of friction, and produces a coastant effort to bring the arm of the jib into a position parallel to the inner part of the rope. Cranes of this construction are in common use in warehouses in London, and all parts of the country. Watt’s Jib Crane,—Fig 1 is a side view of the crane, shewing the jib ; fig. 2 is a back view, shewing the chain, barrels, and edges of the wheels and pinions; fig. 3 is a fulcrum, used in shifting the crane from place to place. The same reference- letters are put to the same points in both figures. A B is the upright shaft. It is made of a firbalk 12} inches square, and 23 feet long. Its lower pivot turns in a eross step at A, and its upper one in a cross at B, supported by four gy- ropes, two of which g g are shewn ifi each figure. Imme- diately above the pivot are two strong plates of cast iron, bolted to the opposite sides, for receiving the bolt at D, upon which the jib turns. Above these, the shaft is fortified by side pieces, till it has a breadth of 26; inches, where are fastened the cast. which an edge view is given in fig. 2, and ... which may be traced # behind the wheels * 7 and mºn, in fig. 1. Four brass beds, co- vered by cap squares of the same metal, are placed in these checks, for receiving the axles of the wheels and pinions. Two strong cast-iron blocks, with grooved pul- leys for the chains, are placed at c and r, upon opposite sides of the shaft. CD is the jib, formed of two oak battens, 7% inches by 23 at their lower extremities, and 5% by 23 at their upper. They are 3 inches asunder at the lower extremity; where, and at the serpentine plate at the middle, they are separated by blocks, and they meet within a few feet of the upper extremity. The extremity D is fortified by two strong plates of cast-iron, which go withinside the plates in the shaft, and receive the axle-bolt; and the other two plates at the extremity C, contain a grooved pulley, shewn by the dotted circle at e, and a bolt for fastening the chain C r. The length of the jib from the axle- bolt at D to the centre of the pulley e, is 203 feet. * There are two chain-barrels. The barrel a raises or lowers the weight f, by means of the chain which passes over the pulleys c, d, e, and the barrel v contracts or expands the jib, by means of the chain which passes over the pulley r. The crane-barrel a is about 9% inches in diameter, and the jib-barrel v about 8 inches; and the chains for both are made with circu- lar links from five-eighths inch iron rod. These barrels may be either both worked at the same time, in the same or in opposite directions, or either of them may be worked sepa- rately. The jib-barrel has a single power, produced by the pinion p, of 10 leaves, and 53 inches diameter, acting on the wheel n n, of 76 teeth, and 36; inches diameter. The pinion p’ iron cheeks s s, of. 204 C R A C R A DICTIONARY OF MECHANICAL scIENCE. is moved by the winches q q, which have a lever power of 16 inches. The jib-barrel may be locked by pushing a moveable bolt, till it bear against an arm of the wheel n n. The single power of the crane-barrel is obtained by placing winches (16 inch) on the squares hk (fig. 2), which terminate an arbor passing through the centre of the jib-barrel, and having on its one end the wheel ii, and on its other the pinion h (fig. 2). The pinion h (53 inches diameter, 9 leaves,) moves the wheel b b, which is fastened on the arbor of the crane-barrel, and has 36# inches diameter, and 76 teeth. The double power is obtained by turning the"pinion l by means of the winch m (16 inches), and one on the opposite cnd of the same arbor. The pinion l is 8+ inches diameter, and has 16 leaves, and the wheel i i, which it turns, is 32 inches diame- ter, and has 66 teeth. The check-block d is a single pulley kept in its place by the chains 't, u, and is necessary for secur- ing the action of the jib at all angles of elevation, by preserv- ing the angle D ed, always smaller than the angle Def, it being obvious, from the doctrine of the resolution of forces, that when these angles are exactly equal, the point of the jib will be in equilibrio; but that when they are unequal, it will have a tendency to move in the direction of the greater angle. When Def is the greater, the jib can be prevented from falling down by the jib-chain Cr; but if D ed were the greater, there is nothing to prevent it from rising till it would come in contact with A B. The fulcrum (fig. 3), is, when the crane is to be shifted, placed near the axle-bolt of the jib at D ; then the jib is lowered, and acts as a lever in taking the weight of the crane off the cross-foot. The cross-head of the fulcrum moves on a pivot in the tripod, and by means of it, and easing off two of the-gy-ropes while the opposite ones are hauled in, the crane is moved along in an upright position.—The total cost of such a crane is about £70; and the parts are so constructed that it may be used for many years without requiring the smallest expense for repairs. The power of the jib-barrel, without making allowance for fruction, is about 263, when the winch is in an horizontal posi- tion; but as the resistance of the weight varies with every change in the elevation of the jib, it is not possible to calculate the power which would be necessary to move it with any given weight. The more that the jib is elevated, the less power is required. The single power of the crane-barrel, without mak- ing allowance for friction, is about 24%, and the double power about 101. It is not possible to determine the friction exactly, because it varies both with the weight and the position of the chains, being more as the weight is greater, and the angles formed by the chains less. But the result of experiments made with a load of one ton, and the jib at an angle of about 45 degrees, were as follows:— Single Power. - lbs. Power required to suspend a ton, by calculation, about 91 Titto, by trial, with check block, about ............. 154 Total friction, . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63 Ditto, without check-block,.......... ſº e s e s tº e º e º e ... 12s Friction on check-block, . . . . . . . . . ſº e º 'º e e • * ~ * * e º e s e e 26 Double Power. Power required to suspend a ton, by calculation, about 22 Ditto, by trial, with check-block, about ...... . . . . . . . Total friction, . . . . . . . . . . . . . . . . . © e s e º e º 'º e a s e º e ..... 2 10itto, without check-block, . . . . . . . . . . . . . . . . . . . . ... as Friction on check-block, . . . . . . . . . . . . . . . * * * * * * * * * * g e — sºmsºmºe |Hence the whole friction on the single power is equal to about two-fifths, and that on the double power about one-half of the power employed; and the friction upon the check-block nearly one-seventh of the power in both cases. The small arc, however, over which the winch can traverse, without a great alteration of power, when trial is made by weight, suspended from the winch, and the great strain produced by a pressure of two tons on the machine, render such experiments but very loose approximations.” - As a building crane, this possesses many advantages over those commonly in use, from the complete command it has over every inch of space within the range of the jib. The common building crane, with a fixed jib and moveable truck, commands indeed the same angular range; but then the truck cannot, without an additional power, be removed farther from the shaft, after the crane is loaded, and thus its operation is con- fined. The common . crane is also much less portable, and cannot be moved even for the shortest distance without being taken down—an operation which costs a good deal of time and labour. Indeed, in as far as portability, power, and the com- plete command of a given space are concerned, this crane is decidedly superior to every other; and in every case of build- ing with large stones, where gy-ropes can be used, it deserves the preference. Where gy-ropes cannot be used, Mr. Watt's balance, or counterpoise crane, is equally applicable and excellent. Indeed, the whole machines invented by this inge- nious mechanic, while employed at the construction of the Bell-Rock Lighthouse, form a series of applications of the mechanical powers highly unique and valuable; and shew of how much consequence it would be to the arts and to society, were mechanical genius in common workmen duly appreciated and regarded.—Mech. Mag. vol. ii. No. 54. . . CRANE is also a popular name for a syphon employed in drawing off liquors. This crane or syphon is nothing else - than a bent tube, as AB G. If the shorter end A B be immersed in a vessel of water or other fluid, C, then by applying the mouth to the end G, and sucking till the liquor arrives there, it will continue to flow out at the end G, as long as that end is lower than the surface of the fluid in the vessel C. If there be a mouth- piece at E, then sucking at that mouth-piece (while the end G is stopt with a finger or other- wise,) will make the fluid flow when the obstruc- tion is taken away from G. When the fluid has begun to flow, the hole at E must be stopped up, or the fluid will flow no longer than till the surface in the vessel be as low as E. The reason of the motion of the liquor in the syphon is this:—The perpendicular height of the column B G being greater than B A, the pressure of the atmosphere being the same at both orifices, supposing them of equal area, therefore the weight at G will cause the fluid to flow out there, while the pressure of the atmosphere will force more liquor up at the end A, and thus the motion will continue so long as there is any fluid in the vessel, pro- vided the end G is lower than the end A of the syphon. Hence it is evident, that the height from the surface of the fluid to the top B must not exceed the altitude of a column of the fluid whose weight is equal to the pressure of the atmosphere on the same base, or the fluid may be drawn up by sucking at the aperture E, which must be closed as soon as the liquor is made to run. Many improvements have been made on this instrument, which it is not our purpose to repeat here. . CRANIOLOGY, is a science by which it is attempted, from the external shape of the skull, to form an opinion of the animal propensities and intellectual powers. A few words will serve to shew the principle on which it is founded. That the intel- lectual powers and animal propensities have their seat in the brain, has generally been admitted, but according to the doc- trines of craniology, of which Drs. Gall and Spurzheim have C * Still it is evident, that could the check-block be dispensed with, the power of the crane would be very much increased. Now, if the point of the jib did not require to be very much raised, the block might be dispensed with, by giving the pulley c a situation lower down to the shaft, such as x; but if it were brought very low, the chain would not coil properly on the barrel. This might, however, be obviated, by placing the crane-barrel on the other side of the shaft, and bringing the chain down the back of the jib from the pulley e, without passing it over any other pulley whatever. As, however, the placing of the barrel in this situation would prevent the jib from being brought so near to the shaft as it can be with the check-block; and as, not- withstanding the friction on the block, the crane is sufficiently powerful, the alteration is a matter of less importance. C R A C. R. O 205 DICTIONARY OF MECHANICAL SCIENCE. ... been the chief propagators, these do not depend on the brain generally, but each distinct faculty and propensity has its seat in a particular portion of the brain. If therefore any part of the brain be unusually large in any individual, that individual will be distinguished for an extraordinary degree of the intel- lectual faculty, or animal propensity, of which the enlarged portion of the brain is the seat. If, on the other hand, any portion of the brain be unusually small, he will be remarkable for a deficiency of the particular faculty or propensity of which the diminished portion is the seat. As the enlargement of any portion of the brain will produce an elevation of the skull, par- ticularly in infancy, when the bones are soft, the craniologists endeavour, by observing the protuberances of the skull, to form a judgment of any individual’s intellectual powers or animal propensities. Drs. Gall and Spurzheim have attempted to fix, from observation of a number of remarkable individuals, what portions of the brain are the seat of the different faculties and propensities, and have accordingly divided the surface of the cranium into portions like the counties in a map of England. But the whole of this appears to the editor and author of this Dictionary absolute nonsense. Such a system as this ought to have for its support observa- tions on a very great number of individuals, and the cases which bear against it, as well as for it, ought to be candidly stated. The small number of cases, under each head in Dr. Spurzheim's work, is very remarkable, and the blunders made by professed craniologists, who have attempted to give the character of individuals whose skulls they have examined, and who were unknown to them, have much tended to destroy all faith in the accuracy of its conclusions. It also deserves to be noticed, that there are external elevations of the skull, where there are no corresponding internal elevations of the brain. The ridicule to which the subject has been exposed, has pro- duced a great zeal in its professors, and whilst that continues, we may expect them to trumpet forth cases in their favour, and to say little of such as do not tend to bring credit to their favourite science. - CRANK, in Mechanics, a square piece projecting from a spindle, serving by its rotation to raise and fall the pistons of engines. It also denotes the iron support for a lantern, and the iron made fast to the stock of a bell. CRAPE, a light stuff resembling gauze, made of raw silk gummed and twisted on the mill, and woven without crossing. CRATAEGUS, Wild Service Tree, Hawthorn, &c. a genus of the digynia order, in the icosandria class of plants, ranking in the natural method under the 36th order, pomaceae. There are 23 species, among which the wild service, or maple-leaved service, a large tree that grows in England, Germany, Switzer- land, and France, is valuable for its timber. CRATER, the Cup, is an ancient constellation, sufficiently typical by its place between the meridian intersecting the Lion and Virgin, of its use at the summer solstice, when Taurus opened the year. The fable which attributes this goblet to Bacchus, is a finely allegorized symbol of Noah's planting the vine ; and the translation of the cup to a place in the heavens corresponding with the primitive solstice of astronomy, gives some support to the hypothesis that assigns to Bacchus an Asiatic origin.—The boundaries and contents of this constel- lation are: north by Virgo, east by Corvus, south and west by Hydra. There are 13 stars in this asterism, of which 9, s, 6, Y, &, and n, form the demi-circumference of the lip. a Alkes to the south, and 3, determine the bottom of the vessel. CRAX, the Curassou, a genus of birds belonging to the order of galinae, of which there are five species, natives of India, Africa, and South America. CRAYON, a general name for a coloured stone, earth, or other substance, used in designing or painting in pastel, whe- ther reduced to a paste, or used in their primitive consistence. In this last manner red crayons are made of blood stone or red chalk, black ones of charcoal and black lead, &c. Crayons of all other colours are compositions of earth. CRAYON PAINTING, requires, in many respects, a treat- ment different from that in oil, because all colours used dry are of a warmer complexion than when wet with oils, for which reason, to produce a rich picture, a greater portion of what are termed cooling tints, must be applied in crayon painting, than would be proper in oil. The paper for crayon painting should be strong blue or gray, and free from knots. The artist should work sitting with the crayons in his lap, and the part of the picture he is painting should be rather below his face. The windows should be darkened to the height of six feet from the floor, and the subject to be painted so placed that the light may fall with advantage on the face. - CREPITATION, or Detonation, in Chemistry, the noise made by some salts over the fire in calcination. In Surgery, the sound made by the ends of bones when the limb is moved, that the existence of a fracture may be ascertained. - CREPUSCULUM, in Astronomy, twilight; the time from the first dawn or appearance of the morning to the rising sun; and again, between the setting of the sun and the last remains of day. Pappus derives the word from creperus ; which, he says, anciently signified uncertain, doubtful, viz. a dubious light. The crepusculum is usually computed to begin and end when the sun is about 18 degrees below the horizon; for then the stars of the sixth magnitude disappear in the morning, and appear in the evening. It is of longer duration in the solstices than in the equinoxes, and longer in an oblique than in a right sphere. The crepuscula are occasioned by the sun’s rays refracted in our atmosphere, and reflected from the particles thereof to the eye. See Twilight. CRESCENT, in Heraldry, a bearing in the form of a new In OOI!. - CRESCENTIA, the Calabash Tree, a genus of the angiosper- mia order, in the didynamia class of plants, ranking in the natural method under the 25th order, putamineae. There are two species; 1. The cujete, with long narrow leaves, and a large oval fruit, is a native of the West India islands. Its height is 20 or 30 feet, and the flowers, which are of a yellowish green colour, striped and spotted with brown, are succeeded by large fruit of a spherical or oval form. 2. The cucurbitana or broad-leaved calabash, rises to the height of 15 or 20 feet; the flowers are smaller than those of the preceding, and of a deeper yellow. The fruit is round or oval. The shells of both are made use of for drinking cups, punch-bowls, and other pur- poses, some of them will hold fifteen pints of water. The wood of the tree is made into stools and other furniture. CREST, in Armoury, the top part of the helmet, generally ornamental. In Heraldry, it is that part of the casque or helmet next the mantle. CRITHMUM, Samphire, a genus of the digynia order, in the pentandria class of plants, ranking in the natural method under the 45th order, umbellatae. There are three species, the prin- cipal of which is the maritimum or common marine samphire, which has a fibrous penetrating root ; thick succulent branch- ing stalks, rising two feet high ; ſleshy leaves, with round yel- low flowers. It grows on the sea-coast among gravel and rocks. The principal use of it is as a pickle. CROCUS, Saffron, a genus of the monogynia order, in the triandria class of plants, ranking in the natural method under the 6th order, ensatae. There are two species, and of each several varieties. • . CROISADE, CRUs Ape, or CRUZADo, a name given to the expeditions of the Christians against the Infidels, for the con- quest of Palestine; so called, because those who engaged in the undertaking wore a cross on their clothes, and bore one on their standard. This expedition was also called the holy war, to which people flocked in great numbers out of pure devotion, the pope's bulls and the preaching of the priests of those days making it a point of conscience. The several nations engaged in the holy war, were distinguished by the different colours of their crosses: the English wore white, the French red, the Flemish green, the Germans black, and the Italians yellow. From this enterprise several orders of knighthood took their rise. They reckon eight croisades for the conquest of the Holy Land; the first begun in the year 1095, at the solicitation of the Greek emperor and the patriarch of Jerusalem. CROMLECH, in British antiquities, huge broad flat stones, raised upon other stones set up on end. They are common in Anglesea, and are supposed by some persons to have been tombs, though others imagine that they were altars for religious services. CROSS, an instrument used in surveying, for the purpose of 3 G - 206 G R O C. R. Y DICTIONARY OF MECHANICAL SCIENCE. raising perpendiculars. It consists merely of two pair of sights set at right angles to each other, mounted on a staff, of a convenient height for use. The method of using it is, to get in a line with one pair of sights, the marks at the extremities of the base line, or that on which the perpendicular is to be raised, and through the other pair the mark or object to which the perpendicular is to be measured; and the line or distance between the foot of the staff and the object will be the perpen- dicular required. See SURVEYING. CRoss-Multiplication. See Duo Decimals. CRoss-Staff, or Fore-Staff, an instrument formerly used by mariners, for taking the meridian altitude of the sun or stars. CROTALUS, Rattle-Snake, a genus belonging to the order of amphibia serpentes. The banded rattle-snake is from three to five feet long, of a yellowish brown colour, marked through- out with transverse streaks or spots of deep brown, and from the head down the neck run two or three stripes of the same colour; the head is large, flat, and scaly; the rest of the upper part covered with large oval scales; the under parts are of a dingy colour, marked with numerous freckles; at the end of the tail is the rattle, consisting of several horny processes, which the animal elevates and shakes when irritated or disturbed. The rattle-snake lives upon frogs, squirrels, and birds. The two last it catches in an extraordinary manner, placing itself under the tree where they rest, and by shaking the rattle awakens them ; they then flutter and jump about from spray to spray, till, tired and 'frightened, they fall into the mouth of the enemy beneath. Rattle-snakes abound in North and South America. Their bite is fatal, but they never attack a person without provocation. The striped rattle-snake, of a deep brown colour above, with pale yellow streaks forming large lozenges down the back, is also a native of America, and equally venom- ous. The wood rattle-snake is of a lighter colour than the two preceding. And the military rattle-snake, of a gray-brown, shaded on the back with red and marked with black spots, is smaller than the other kinds. CROTCHET, in Music, a note or character of time marked thus, " , equal to half a minim and double a quaver. CROTCHETS, marks enclosing a word or sentence to be distinguished from the rest, thus, [ ] or ( ). CROTON, Wild Ricinus, which grows naturally in the south of France, and from it is made the turnsole used for colouring wines and jellies. This is made of the juice lodged between the empalement and the seeds; and if rubbed on cloths at first appears green, but soon changes to a purple. If these cloths are put into water, they will dye it of a claret colour. The rags thus dyed are brought to this country, and sold under the name of turnsole. CROW, in Mechanics, a kind of iron lever, sharp at one end and a claw at the other, used for heaving or pushing great weights. CROWN, in Astronomy. See CoRoNA. CROWN, in Geometry, a plane ring, included between two concentric perimeters, generated by the motion of part of a right line round the centre, to which the moving part is not contiguous. The area of a crown is had by multiplying its breadth by the length of the middle periphery; for a series of a + 'w , i. e. the sum terms in arithmetical progression being n x 2 of the first and last multiplied by half the number of terms, the a + 'w - middle terms must be , therefore, that multiplied by the 2 breadth or sum of all the two terms will give the crown. CRow N, is also a silver coinage of England, and many other countries; the English crown is equal in value to 5 shillings; the Danish crown is 2s. 84d. ; German, 4s. 73d. ; French, 4s. 93d. sterling. CROWN-WHEEL of A WATCH, the upper wheel, which, by its motion, drives the balance. In royal pendulums it is called the swing wheel. CROWN-WORK, in Fortification, an outwork having a large gorge, and two long sides terminating towards the field in two demi-bastions. It is intended to enclose a rising ground, or to cover an entrenchment. CROW’S BILL, a surgical instrument for extracting balls. and other substances from wounds. CROW’S FEET, in Military affairs, machines of iron having four points so made that whatever way they fall there is a point upwards; these are thrown upon breaches, or in passes, to lame the horses of the enemy. - * CRUCIBLE, a chemical vessel made of earth, and so tem- pered as to endure the strongest heat. - CRUSTACEOUS Fish, are those covered with shells, con- sisting of several pieces or scales, as crabs, lobsters, &c. CRUX, the Cross, is an asterism containing five stars, viz. one of the 1st magnitude, two of the 2d, one of the 3d, and one of the 4th. Four of these stars are in the form of a cross, and the most northerly and southerly are always in a line with the south pole. They are, therefore, the Pointers for discerning, in the southern hemisphere, the Antarctic pole. a, of the 1st magnitude, in the foot of the Cross, has 12 ho. 16' 48" right ascension in Time (Ann. War. 3".23), and 62° 6'49" south declination, (Ann. War. -- 20".00.) y, of the 2d magnitude, in the top of the Cross, has 12 ho. 21' 20", (Ann. War. 3".24), and 56°6'41" south declination, (Ann. War, --, 19".97.) 3, of the 2d magnitude, in the arm, has 12 ho. 37' 24", (Ann. War. 3'.41,) and 58°42'53" south declination, (Ann. War. -- 19.80.) - CRYSTAL, in Natural History, the name of a large class of fossils, hard, pellucid, and colourless. CRYSTALLINE HEAVENS, in the old Astronomy, two orbs imagined between the primum mobile and the firmament, in the Ptolemaic system, in which the heavens are supposed solid, and only susceptible of a single motion. These orbs are said to have been introduced by Alphonsus, in order to explain what the ancients called the motion of trepidation or titubation. CRYSTALLIZATION. When fluid substances become Solid they frequently assume regular polyhedral forms, which are called crystals, and the bodies which do so are said to be Susceptible of crystallization. Many minerals are found which are thus arranged into regular forms. To enable the particles of bodies to assume that regular form which crystals exhibit, they must have freedom of motion; and, accordingly, the first step is to confer a liquid or aeriform State, by solution in water. When common salt is dissolved in water, the particles will be too far asunder to exert reciprocal attraction; in other words, they will be more powerfully attracted by the water than by each other. If we now get rid of a portion of the water by evaporation, the saline particles will gradually approach each other, and will aggregate accord- ing to certain laws, producing a regular solid of a cubic form. If the process be slowly conducted, the particles unite with great regularity; if hurried, the crystals are irregular and confused. - There are certain bodies which may be liquefied by heat, and during slow cooling may be made to crystallize. This is the case with many of the metals, and with sulphur. Some other substances, when heated, readily assume the state of vapour, and during condensation present regular crystalline forms, such as iodine, benzoic acid, camphor, &c. - The hardness, brilliancy, and transparency of crystals often depend upon their containing water, which sometimes exists in them in large quantities. Thus sulphate of soda, in the state of crystals, contains more than half its weight. . This is called water of crystallization. Some salts part with it by a simple exposure to dry air, when they are said to efiloresce; but there are other salts which deliquesce, or attract water from the atmosphere. Crystallization is accelerated by introducing into the solution a mucleus, or solid body, upon which the process begins, and manufacturers often avail themselves of this circumstance. A strong saline solution excluded from the air will frequently crystallize the instant that air is admitted, a circumstance referred to atmospheric pressure. In other cases agitation produces the same effect. The presence of light also influences the process of crystallization. Thus the crystals collected in camphor bottles in druggists' windows, are always most copious upon the surface exposed to the light. Crystallized bodies affect one form in preference to others. The fluor spar of Derbyshire crystallizes in cubes; so does common salt; nitre in the form of a six-sided prism; and sulphate of magnesia C U B °C U B ‘907 DICTIONARY of MECHANICAL scIENCE. in that of a four-sided prism. These forms are liablé to vary. Fluor spar and salt crystallize sometimes in the form of octa- hedra ; and there are so many forms of carbonate of lime, that it is difficult to select that which most commonly occurs. Rome de Lisle referred these variations of form to certain transactions of an invariable primitive nucleus. Bergman suspected the existence of a primitive nucleus in all primitive bodies. When Haüy entered this field of inquiry, he not only corroborated the opinions of Bergman, but traced with much success the laws of crystallization, and pointed out the mode of transition from primitive to secondary figures. Dr. Wollaston supposed the primitive particles to be of a spherical form, and that their mutual attraction produces crys- tallization in the various regular forms in which it appears.- When alum is dissolved in water, various figures appear upon it. tain gems, have long known that they only afford smooth sur- faces when broken in one direction.—Watkin's Cyclopaedia. CRYSTALLOGRAPHY, the science which attempts to explain the laws by which crystallization takes place. CRYSTALLIZING the Surface of Tin and other Metals.- The process of giving the new ornamental surface on metals or metallic compositions, consists in employing those acids and saline compounds and substances which chemically act upon tin, and which, when employed in the manner to be stated, pre- sently give to the metal or metallic compositions to which they are applied, the appearance of a crystalline surface variously modified; to produce this effect, the metal or metallic compo- sition ought to be previously tinned or covered with a thin coat of tin. If the metal be pure tin, it requires no previous prepa- ration. All grease remaining on the tinned surface, in conse- quence of tinning, is to be taken off with a solution of potash, soap, or any alkaline substances. The tin or tinned surface should then be washed with pure water, dried, and heated to a temperature which the hand can bear; when the surface has thus been cleaned and heated, any of the acids which act upon tin, or the vapours of these, will cause the desired appearance of crystallization, but preference is given to the following com- position, which may conveniently be laid over with a brush or a Sponge: take one part by measure of sulphuric acid, dilute it with five parts of water. Take also one part of nitric acid, and dilute it with an equal bulk of water, and keep each of the mixtures separate; then take ten parts of the sulphuric acid, dilute it in the manner before stated, and mix it with one part of the diluted nitric acid, and then apply this mixed acid to the tin, or to the tinned surface, with a pencil or sponge, as above directed, and repeat the application of the said composition for several times successively, or until the result you expect proves satisfactory: when this has been done, the crystalline surface may be covered with a varnish or japan, more or less transparent and colourless, or coloured; the whole must now be polished. CUBATURE, is the finding the solid content of any proposed body, the same as quadrature signifies the finding the super- ficial area. CUBE, or HEXAHEDRON, a solid regular body, consisting of six equal square sides. It is supposed to be generated by the motion of a square plane along a line equal and perpendicular to one of its sides. To determine the Surface and Solidity of a Cube.—Multiply one side by itself, which will give one square ; this multiplied by 6 will give the whole surface. Also, multiply one side twice by itself, that is, cube it, ahd that will give the solid con- tent required. CUBE, Duplication of the, is the finding of the side of a cube that shall double in solidity a given cube. It cannot be done geometrically, as it requires the solution of a cubic equation, or the finding two mean proportionals. Let a be the side of the given cube, and z that of the double one, then 23 = 2 as, or a” : z* : : z : 2a, therefore, if a. and z be the first and second terms of a set of continued proportionals, then aº ; 22 is the ratio of the square of the first to that of the second, which is the same as the ratio of the first term to the third, or the second to the fourth, or of z to 2a : therefore z being the second term, 2 a will be the fourth; so that z, the side of the cube sought, is the second of four terms in continued proportion; the first and Those who are in the habit of cutting and polishing cer- fourth being a and 2a, i.e. the side of the double cube is the first of the two mean proportionals between a and 2 a. CUBEB, Powder of, though not yet enroll • . macopoeia of London, is an article much used by our medical practitioners, to reduce inflammations of the pudenda, attended with the discharge of a mucus. This disease, sometimes mis- taken for a venereal affection, is perfectly local, and may be easily cured by taking at night and morning a small portion of the powder of cubeb; thus, half an Óuncé of the powder made up into twelve parcels, will make doses for six days, during which time the parts affected may be well syringed with warm water and milk; or about 20 drops of port wine thrown into a glass of lukewarm water, makes perhaps a more efficacious wash. If the inflammation is not reduced in a week, the applications should be continued till the discharge entirely disappears. CUBEBS, the Cubeba of Medicine, is a small dried fruit, resembling pepper, brought from Java. CUBES, or Cube NUMBERs, in Arithmetic, and the Theory of Numbers, are those whose cube root is a complete integer; or they are numbers produced by multiplying a given number twice into itself, or by the multiplication of three equal factors, thus, 1 × 1 × 1 = 1; 2 × 2 × 2 = 8; 3 × 3 × 3 – 27; 4 × 4 × 4 = 64, &c. are cube numbers. To find the Cube Root of a given Number.—1st Method. Separate the given number into periods of three figures each, by putting a point over the place of units, another over the place of thousands, and so on over every third figure, to the left hand in integers, and to the right in decimals; and then find the nearest cube root of the first period, and set it in the quotient. 2. Subtract the cube of the figure of the root thus found, from the first period, to the left hand, and annex the following period to the remainder for a dividend. 3. Divide this dividend by 3 times, the square of the figure of the root above determined, and the first figure of the quotient will be the second figure of the root. 4. Subtract the cube of these two figures of the root from the first two periods on the left, and to the remainder annex the following period, for a new dividend, which divide as before; and so on till the whole is finished. And finally, point off as many figures for integers as there are periods of integers in the proposed number. éd in the Phar- Example. Required the cube root of 41278-242816. 4iz78243816(34.56 root 33 - 27 3 x 3 = 27) 14278 (4 2d figure of the root 41278 1st two periods 343 – 39304 34 × 3 = 3468) 1974-242 (5, 3d figure - 41278-242 1st three periods 3453 = 41063:625 345 x 3 = 357075) 214-617816 (6-4th figure and thus the operation may be carried on till the root be obtained to any degree of accuracy required. This method, however, is extremely laborious, and is seldom or never employed, as other methods have been found in which the approximation is carried on much more rapidly. - 2d Method. Find by trials the nearest rational cube to the given number, and call it the assumed cube. Then, as double the assumed cube added to the given number, is to double the given number added to the assumed cube, so is the Yööt of the assumed cube to the required root, nearly. Or, as the first sum is to the difference of the given number and assumed cube, so is the assumed root to the difference of the roots, nearly.—By taking the cube of the root thus found, for the assumed cube, and repeating the operation, the root will be had to a still greater degree of exactness. 3d Method. Point off the given number in periods of three figures each, reckoning from the units’ place: then find the cube of the first period on the right hand, set it down under that period, and subtract the one from the other, and to the remainder bring down the next period. To find the cube of this period. square the quotient, and multiply the product by 208 C U M C U R DICTIONARY OF MECHANICAL SCIENCE, 300 for a new divisor. Find how often this divisor is contained in the dividend, set it down, and bring down the two first periods in the dividend; cube the quotient figures, place their value under the original dividend periods, and subtract as before, and proceed thus till all the dividend is brought down. Example. 14886936 is the number whose cube root is sought. - 14886'936 (246 2 × 2 × 2 = / 8 6'886 2 × 2 × 300 = 1200) 16886 24 × 24 × 24 – 13824 3062936 24 × 24 × 300 = 172800) 14°886-936 246 × 246 × 246 – 14'886'936 CUBICAL EQUAtion, in Algebra, one whose highest power * of three dimensions, as a:3 = a – bº, or a " + 2 a.” E º, &c. CUBIT, a measure of length equal to a man’s arm from the elbow to the extremity of the fingers. Dr. Arbuthnot states the English cubit at 18 inches, the Roman at 1 foot 5'406 inches, and the Hebrew at 1 foot 9.888 inches. CUCULUS, the Cuckoo, a genus of birds belonging to the order of picac. The cuckoo appears in the spring, and takes its departure early in July. Some of these birds, however, have been found to winter in this island, taking up their abode in hollow trees, where they have lain in a torpid state. The cuckoo does not rear her own offspring, but selects the nest of some other bird, particularly that of the hedge-sparrow, in which she deposits her eggs. When the sparrow has sat her usual time, and disengaged the young cuckoo from her shell, her own young ones are soon turned out by the intruder, who remains in possession of the nest. There are many more male cuckoos than females, for when five or six have been taken in a trap, not a female has been found among them. Cuckoos may be brought up tame. They will eat bread and milk, fruit, insects, and flesh. CUCUMBER, Cucumis, a genus of the syngenesia order, in the monoecia class of plants, ranking in the natural method under the 34th order, cucurbitaceae. There are 13 species. CUCURBIT, in Chemistry, an earthen or glass vessel, so called from its resemblance to a gourd. CUCURBITA, the Gourd and Pompion, a genus of the synge- nesia order, in the monoecia class of plants, ranking in the natural method under the 34th order cucurbitaceae. There are seven species. * - CUIRASS, a piece of defensive armour, made of iron plate, well hammered, serving to cover the body from the neck to the girdle, both before and behind. . - CULEX, the Gnat, a genus of insects of the order of diptera, of which there are seven species. Before they attain the flying state, they are small grubs in the water, after which they turn to chrysalids, then pass to the state of a gnat, and fly into the air. CULMINATE, to be vertical to, or on the meridian : hence the culminating point, is that point of a circle of the sphere that is on the meridian. CULMINATION, in Astronomy, signifies the passage of any heavenly body over the meridian, or its greatest altitude during its diurnal revolution. In order to find the time of a star's culminating, we must estimate the time nearly, and find the right ascension both of the sun and star corrected for this estimated time; then the difference between these right ascen- sions, converted into solar time, at the rate of 15 degrees to the hour, gives the time of southing. CULVERIN, a long slender piece of ordnance or artillery, for carrying a ball to a great distance. CUMINUM, Cummin, a genus of the digynia order, in the pentandria class of plants, ranking in the natural method under the 45th order, umbellatae. There is only one species. which is an annual, that rises nine or ten inches high in warm countries. The ſlowers are of a pale blue colour; and the seeds have an aromatic taste. These are used in the emplastrum cumini of the Pharmacopoeia. CUNEUS, the Latin term for wedge. See WEDGE. CUNITIA, a celebrated lady of Silesia, authoress of a mathematical work entitled “Urania Propitia,” published in 1650, in Latin and German; in which are contained various accurate astronomical tables calculated upon Kepler's hypo- thesis. CUPEL, a shallow earthen vessel resembling a cup, from which it derives its name, is made of phosphate of lime, or the residue of burned bones rammed into a mould, which gives its figure. This vessel is used in assays wherein the precious metals are fused with lead, which becomes converted into glass, and carries the impure alloy with it. CUPELLATION, the art of refining gold or silver by means of a cupel. For this purpose another vessel called a muffle is used, within which may be placed one or more cupels. CUP-GALLS, formed on the leaves of the oak and other trees, resemble a drinking-glass with a cover, which last is flat, and has a small protuberance in the centre. - CUPOLA, in Architecture, a spherical vault, or the round top of the dome of a church. CUPPING, in Surgery, the operation of applying cupping- i. for the local discharge of blood and other humours by the skin. CUPRESSUS, the Cypress-tree, a genus of the monadelphia order, in the monoecial class of plants, ranking in the natural method under the 51st order, coniferae, of which there are seven species, all raised from seeds, and sometimes from cuttings. The wood of the evergreen cypress is said to resist worms, moths, and putrefaction, and to endure for ages. This tree has also been celebrated as a remedy in pulmonic diseases, from its supposed property of meliorating the air by its balsamic exhalations. CURATE, the parson, or vicar of a parish, who has the charge or cure of the parishioners' souls; or, a person substi- tuted by the incumbent, to serve his cure in his stead. CURATOR, among Civilians, one appointed to manage the affairs of minors, or persons incapable of acting for them- selves. CURCULIO, the weevil, a genus of insects belonging to thc order of coleoptera; and of which there are fifteen species, whose larvae commit great ravages in corn-lofts, burying them- selves in the grain, and entirely devouring the meal. When the insect arrives to its full size it becomes a chrysalis. Other larvae ſix themsclves in beans, peas, and lentiles, artichokes, thistles, and the leaves of the elm tree. CURCUMA, Turmeric, a genus of the monogynia order, in the monandria class of plants, ranking in the natural method under the 8th order, scitamineae, and of which there are three species, that grow naturally in India, whence the roots are brought to Europe, to be used in dyeing yellow ; and in medi- cine as a remedy for the jaundice. * CURFEW, a signal given in cities taken in war, &c. to the inhabitants to go to bed, and advertise the people to secure them- selves from the robberies and debaucheries of the night. The most eminent curfew in England, was that established by Wil- liam the Conqueror, who appointed, under severe penalties, that, at the ringing of a bell, at eight o'clock in the evening, every one should put out their lights and fires, and go to bed : whence to this day, a bell, rung about that time, is called a curfew-bell. º CURING FISH AND BAco N.—The following simple and easy . mode of preserving mackarel, pilchards, herrings, and Sprats, has been proved by experience to answer well. Half fill some water-tight casks or vats, with a brine made from about 28 parts of solid salt to 72 parts of fresh water. Into this brine, the fish, gutted or not, are thrown as fresh as possible, sufficient to nearly fill the vessel. Some moisture will exude from the fish during the pickling, therefore add more salt to saturate it; and as the brine is always weakest in the upper part, a piece of basket work, or lattice work frame, should be provided, to fit inside of the cask or vat, and sunk an inch or two below the sur- face of the brine, upon which is to be placed some large lumps of solid salt, which will keep fully saturated the whole of the liquor, and keep it so as long as the lumps remain undissolved. c U R C U S DICTIONARY OF MECHANICAL SCIENCE. 209 The solidity of these lumps admit of their being applied several times, or as often as the vessels are replenished with fish. The fish are to remain thus immersed in the liquor for five or six days, when they may be taken and packed in large grained salt, as usual. Various sorts of provisions are best preserved by this process, particularly bacon, which is not so liable to become rancid. ** CURRANTS, the fruit of a species of grossularia. The white and red sorts are mostly esteemed; the black are em- ployed to flavour English spirits, and counterfeit French brandies. The jelly is reckoned efficacious in sore throats. Currants also signify a small kind of grapes brought from Zante and Cephalonia. CURRENTS, in Navigation, are certain settings of the stream, by which ships are obliged to alter their course, in order to arrive at the destined port. The setting of the current is that point of the compass to which the waters run ; and the drift of the current is the rate it runs per hour. For the method of determining their course and drift, see Robertson’s “Navigation,” vol. ii. book 7, sect. 8, where the sailing in currents is largely exemplified. CURRYING, the method of preparing leather with oil, tal- low, &c. The skins when they come from the tanner are soaked in water; then stretched on a wooden horse, and being well scraped are put to soak again. While wet they are placed on a hurdle and trampled upon, to make them soft and pliant. In the next place they are soaked in train oil, and when taken out are fastened to large tables. Then the currier with an in- strument called a pummel, which is a thick piece of wood, having the under side full of furrows crossing each other, folds, squeezes, and moves them backwards and forwards under the teeth of the instrument, to break their stiffness. This last is called currying: after which operation the skins are either coloured or made white. This last is done by rubbing them with chalk or white lead, and afterwards with pumice-stone. When a skin is to be made black, after it is oiled and dried, the currier passes over it a puff dipt in water impregnated with iron; he next gives it another wetting with a water prepared with soot, vinegar, and gum-arabic. This last operation is repeated till the skin is of a shining black. CURSITOR, an officer belonging to the chancery, who makes out the original writs. There are twenty-four cursitors llotted to several counties. CURSOR, a Runner, or Messenger, a small sliding piece of brass, in some mathematical instruments, as the piece of an equinoxial ring-dial, which slides to the day of the month, the point that slides along the beam compass, &c. - CURTAIN, or CURTIN, in Fortification, that part of the ram- part of a place between the flanks of two bastions, bordered with a parapet five feet high, behind which the soldiers stand to fire upon the covered way and into the moat. CURTATE Distance, in Astronomy, is the distance of a pla- net's place from the sun or earth, reduced to the ecliptic ; or, the interval between the sun or earth, and that point where a perpendicular, let fall from the planet, meets with the ecliptic. CURTATION, is the interval between a planet's distance from the sun, and the curtate distance. - CURVATURE of a LINE, is its bending or flexure, by which it becomes a curve of any particular form and proper- ties. Thus, the nature of the curvature of the circle is such, that every point in the periphery is equally distant from a point within called the centre; and so the curvature of the same circle is every where the same, but the curvature of all other curves is continually varying. The curvature of a circle is so much the more, as its radius is less, being always reciprocally as the radius and the curvature of other curves is measured by the reciprocal of the radius of a circle, having the same degree of curvature as any curve has, at some certain point. Every curve is bent from its tangent by its curvature, the measure of which is the same as that of the angle of contact formed by the curve and tangent. Now the same tangent is in common to an infinite number of circles, or other curves, all touching it and each other in the same point of contact. So that any curve may be touched by an infinite number of different circles at the same point; and some of these circles fall wholly within it, being more curved, or having a greater 23. does not pass through the centre of the sphere. curvature than that curve; while others fall without it near the point of contact, or between the curve and tangent at that point, and so being less deflected from the tangent than the curve is, they have a less degree of curvature there ; conse- quently there is one, of this infinite number of circles, which neither falls below it nor above it, but, being equally deflected from the tangent, coincides with it most intimately of all the circles; and the radius of this circle is called the radius of curvature of the curve; also the circle itself is called the circle of curvature, or the osculatory circle, of that curve, because it touches it so closely that no other circle can be drawn between it and the curve. • * CURVE, in Geometry, is a line, the several parts of which proceed in different directions, and are successively posited towards different points in space. - - A plane CURVE, is that of which the several points in it lie in the same plane ; and when this is not the case, the curve is said to be one of double curvature. |CURVE Lines are distinguished into algebraical or geometri- cal, and transcendental or mechanical. Algebraical or Geome- trical CURVES, are those in which the relation of the abscisses to the ordinates can be expressed by a common algebraical expression. Transcendental or Mechanical CURves, are such as cannot be defined or expressed by an algebraical equation; or when they are expressed by an equation, one of its terms is a variable quantity, or a curve line. Family of CURVEs, is an assemblage of several curves of different kinds, all defined by the same equation of an indeter- minate degree; but differently, according to the diversity of their kind. CURVE of Double Curvature, is used to denote the curve- line, all the parts of which are not situated in the same plane. A curve which can only be traced upon a curve sur- face, and not upon a plane surface, is called a curve of a double curvature. These kinds of curves may be consi- dered as generated by the track of a point which is moved upon a curve surface, the direction of its motion being con- tinually deflected either towards the right, or towards the left hand; thus it happens that the line so described is curved, in two senses; for in effect, is partakes of the curvature of the curve surfaces, and of the continual and successive deflections of the describing point. Two curve surfaces which mutually penetrate each other, form also, in general, by their intersec- tion, a curve of double curvature. Such, for example, is the curve which is formed by the mutual penetration of a right cylinder and a sphere, supposing that the axis of the cylinder We have said in general, for it may happen on account of particular circum- stances, that the intersections of two curve surfaces is a plane, curve. Thus, in the preceding example, if the axis of the cylinder passed through the centre of the sphere, the curve of intersection would be the common circle. Ingenious disquisi- tions on curves of double curvature, have been given by Euler' and La Croix. - . CURVILINEAR, any thing relating to curves, as curvilinear angle, figure, surface, &c. being such as are formed or bounded by curves. CUSCUTA, Dodder, a genus of the digynia order, in the tetrandria class of plants, ranking in the natural method under the dubious order. There are four species, one of which is a native of Britain, viz. The Europaea, dodder, hell-weed, or devil's guts; a singular plant, almost destitute of leaves, creep- ing and fastening on whatever is next to it. It decays at the root, and afterwards is nourished by the plant to which it ad- heres. Hops, flax, and nettles are its common supporters. CUSP, CUSPIs, in Astronomy, properly denotes the point of a spear, but is used to express the points or horns of the moon, or other luminary. CUSP, in Geometry, is used for the point, or corner, formed by two parts of a curve meeting and terminating there. CUSTOM, a law, not written, which from long usage and con- sent becomes a matter of right. It is either general or parti- cular; the first when allowed throughout England; particular when confined to a particular district. ... "Custom is also a very comprehensive term, denoting the manners, ceremonies, and fashions of a people,”which having 3 H 210 c Y (; c Y c DICTIONARY OF MECHANICAL scIENCE. turned into a habit, and passed into use, obtains the force of laws; in which sense it implies such usages as, though volun- tary at first, are yet, by practice, become necessary. Custom is hence defined, a law not written, but established by long usage, and the consent of our ancestors; in which sense it stands opposed to the written law. All customs ought to have a reasonable commencement, be certain, not ambiguous, have had uninterrupted continuance, and not be against the king's prerogative. . . ’ s Custom of London: it is a custom of London, that where a person is educated in one trade, he may set up another; that where a woman uses a trade without her husband, she is chargeable alone, as a femme sole merchant, and, if condemned, she be put in prison till she pays the debt; likewise the bail for her are liable if she absent herself, and the husband, in these cases, shall not be charged. If a debtor be a fugitive, by the custom of London he may be arrested before the day, in order to find better security, &c. These are customs of London, different from those of other places. CUSTOM of Merchants: if a merchant gives a character ºf a stranger to one who sells him goods, he may be obliged to satisfy the debt of the stranger for the goods sold, by the cus- tom of merchants. And when two persons are found in arrears, upon an account grounded on the custom of merchants, either of them may be charged to pay the whole sum due, &c. Various other cases depend on what is understood as the usual custom of commercial men. CUSTOMS, in Commerce, the duties or taxes payable upon the importation or exportation of merchandise. They appear to have been originally levied to reimburse the sovereign for the expense he incurred in protecting foreign trade, and were considered as taxes upon the profits of the merchants, being imposed equally upon all sorts of goods, necessaries as well as luxuries. CUSTOS BREWIUM, the principal clerk in the Court of Common Pleas, who keeps all the writs made returnable in that court, and makes entries of writs of covenant, &c. CUSTOS MESSIUM. Monsieur de la Lande introduced this asterism in honour of the celebrated astronomer Messier, and in allusion to his name it has been called the Guardian of the Harvests.--The boundaries and contents are: South by Cassiopeia, east by Cepheus, north by Tarandus, and west by Camelopardalis. Right ascension 35°, and 68° declination north. The stars, about ten in number, are mostly invisible to the naked eye. CUSTOS ROTULORUM, an officer who has the care of the rolls and records of the sessions of peace, also of the commis- sion of the peace. CUT-WATER, in a ship, is the sharp part of the head under the beak or figure. CUTICULA, in Anatomy, a thin membrane close upon the skin or cutis, of which it seems to be a part, and to which it firmly adheres by the corpus reticulare. CúTIS, in Anatomy, the skin, that strong covering which envelopes the whole surface of animals, and which consists chiefly of two parts, a thin white elastic layer on the outside called the epidermis or cuticle; and a thick one composed of many fibres closely interwoven and disposed in different direc- tions, called the cutis or true skin. CUTLERY, in the general sense comprises all those articles denominated edge-tools, but it is more particularly confined to the manufacture of knives, forks, scissars, penknives, razors, swords, and surgical instruments. CUTTER, a sloop-rigged vessel built sharp for sailing; generally used in smuggling, or in the navy to watch the coast, and to look after vessels engaged in contraband trade. CYCAS, a genus of plants belonging to the first natural order palmae. The fruit is a dry plum with a bivalve kernel. There are two species; 1. The circinalis or sago tree, which grows in the East Indies, particularly on the coast of Malabar. It rises to the height of forty feet, and the leaves are seven or eight feet long. The flowers grow in long bunches at the foot- stalks of the leaves, and are succeeded by oval fruit, about the size of large plums, of a red colour when ripe, and of a sweet taste. Each contains a nut enclosing a white kernel which tastes like the chestnut. The inhabitants of India saw the body of the tree into pieces, then beat them into a mortar and pour water upon it. When strained, a fine mealy substance comes off, which is made into bread. The same meal finely powdered is made into sago. 2. The cyas revoluta, or bread tree of the Hottentots, discovered by Thunberg, has a pith which abounds in the trunk, and is collected and tied up in skins, and buried some weeks till it is tender enough to be kneaded, and then it is made into loaves of frumenty. CYCLE, a certain period or series of numbers, proceeding orderly from first to last, then returning again to the first, and so circulating perpetually. Cycles have chiefly arisen from the incommensurability of the revolutions of the earth and celestial bodies to one another. The apparent revolution of the sun about the earth, has been arbitrarily divided into 24 hours, which is the basis or foundation of all our mensuration of time, whether days, years, &c. But neither the annual motion of the Sun, nor that of the other heavenly bodies, can be measured exactly, and without any remainder, by hours, or their multiples, That of the sun, for example, is 365 days, 5 hours, 49 minutes, nearly ; that of the moon, 29 days, 12 hours, 44 minutes, nearly. Hence, in order to express these fractions in whole numbers, and yet in numbers which only express days and years, cycles have been invented; which, comprehending several revolutions of the same body, replace it, after a certain number of years, in the same points of the heaven whence it first departed; or, which is the same thing, in the same place of the civil calendar. The most remarkable of these are the following:—The Cycle of the Sun, or Solar Cycle, is a revolution of 28 years, in which time the days of the months return again to the same days of the week; the sun's place to the same signs and degrees of the ecliptic on the same month and days, so as not to differ one degree in 100 years; and the leap-years begin the same course over again, with respect to the days of the week on which the days of the month fall. The Cycle of the Moon, commonly called the Golden Number, is a revolution of 19 years; in which time the conjunctions, oppositions, and other, aspects of the moon, are within an hour and a half of being the same as they were on the same days of the months 19 years before. The Indic- tion is a revolution of 15 years, used only by the Romans, for indicating the times of certain payments, made by the subjects to the republic. It was established by Constantine, A. D. 312. The year of our Saviour's birth, according to the vulgar aera, was the ninth year of the solar cycle, the first year of the lunar cycle; and the 312th year after his birth, was the first year after the Roman Indiction. Hence, to find the year of the Solar Cycle, add 9 to any given year of Christ, and divide the sum by 28, the quotient is the number of cycles elapsed since his birth, and the remainder is the cycle for the given year: if nothing remains, the cycle is 28. - To find the Lunar Cycle.—Add one to the given year of Christ, and divide the sum by 19; the quotient is the number of cycles elapsed in the interval, and the remainder is the cycle for the given year: if nothing remains, the cycle is 19. Lastly, subtract 312 from the given year of Christ, and divide the remainder by 15, and what remains, after this division, is the Indiction for the given year: if nothing remains, the Indiction is 15. . The Cycle of Easter, also called the Dionysian Period, is a revolution of 532 years; found by multiplying the solar cycle 28, by the lunar cycle 19. If the new moons did not anticipate upon this cycle, Easter-day would always be the Sunday next after the full moon which follows the twenty-first of March; but, on account of the above anticipation, to which no proper regard was had before the late alteration of the style, the eccle- siastic Easter has several times been a week different from the true Easter, within this last century; which inconvenience is now remedied by making the table, which used to find Easter for ever, in the Common Prayer Book, of no longer use than the lunar difference from the new style will admit of. The ear- liest Easter possible, is the 22d of March; the latest, the 25th of April. Within these limits are thirty-five days, and the number belonging to each of them is called the Number of Direction; because, thereby, the time of Easter is found for any given all". CYCLOGRAPH, all instrument, as its name imports, used for describing the arcs of circles, in some cases where com- passes cannot be employed. C Y C c y D 1) ICTIONARY OF MECHANICAL SCIENCE. 211 The most simple cyclo- graph, next to the com- passes, is that commonly used by artificers in de- scribing arches for the tops of doors, windows, &c. D C E represent two ID rods, forming any determined angle at C ; A and B are two fixed pins or nails, between which the cyclograph D C E is made to move, keeping both legs in constant contact with those points; so will the angle C describe the arch of a circle, as is obvious, because all angles in the same segments are equal to each other; and, therefore, conversely, if the angles be equal, the curve is the arc of a circle. CYCLOID, (in Geometry,) or TRochord, a mechanical or transcendental curve, possessing several very curious properties, the generation of which will be understood from the following figure. Con- ceive the circle E P E to T rotate along the right line A B, in the same plane with the circle, until a fixed point in the circumference, which at first touched the right line at A, touches it again at B, after an entire E ID revolution; then the curve A C B, traced upon the plane by the point P, is ealled a cycloid. The line A £3 is called the base, and D C the azis of the cycloid; and the circle E PE the generating circle. If the point P be without the circumference of the generating circle, then the curve described by that point is properly called a trochoid, but commonly also a curtate cycloid. And if the point P be within the circumference of the generating circle, then the curve is called the prolate cycloid. º If the generating circle, instead of revolving along a right line, as in the above figures, is made to revolve along either the concave or convex circumference of another circle, then the curve so generated is called an Epicycloid ; the principal prox. perties of which will be found under that article. The cycloid is a modern curve, the invention of which has been attributed to Bovillus, who wrote about the year 1501. We cannot, in this place, enter into an investigation of the several curious properties which belong exclusively to the cy- cloid, as this would occupy much more space than can with propriety be allotted to this article; we must, therefore, con- tent ourselves with enumerating the principal of them. Properties of the Cycloid.—Draw any right ordinate FG H, fig. 1. above, join C G, and from H draw H I parallel to C G, meeting the axis D C produced in I. Then, 1. I H is a tangent to the cycloid at the point H. 2. The circular arc C G is equal to the right line H. G. 3. The semi-circumference C G D – Semi- base D B. 4. The cycloidal arc C H = double the chord C. G. 5. The semi-cycloidal arc C B = double the diameter CD. 6. The area of the cycloid A C B A = triple the area of the circle C G D. 7. The three spaces A C D, the circle C G D, and CBD, are equal to each other. 8. The upper segment of a cycloid cut off by a line parallel to the base, at # of the axis from the vertex, is equal to the regular hexagon inscribed in the generating circle. 9. The solid generated by the revolution of the cycloid about its base A B, is, to its circumscribing cylin- der, as 5 to 8, 10. The solid generated about the tangent pa- rallel to the base, is, to its circumscribing cylinder, as 7 to 8. 11. And the solid generated about the tangent parallel to the axis, is, to its circumscribing cylinder, as 6 to 8. CYCLOPTERUS, the Sucker, a genus of fishes belonging to the order of amphibia mantes, of which there are three species, | 1. The lumpus or lump fish, is in length nineteen inches, and weighs seven pounds. These fish abound in the Greenland seas, and on the coast of Scotland. 2. The liparis or sea snail, of a soft unctuous texture, and soon melts away, is in length five inches, and the colour a pale brown. 3. Cyclopterus minor, or the lesser sucking fish, is found on the coast of Britain. It is about four inches, and fastens very tenaciously to stones and rocks. CYDER. We have already treated of CIDER, and as the two modes of spelling this word frequently occur, we have taken leave, under the present orthography, to insert some directions which may prove useful, in those families and countries where cyder is a common drink. Let your fruit be as near the same ripeness as possible, otherwise the juice will not agree in fer- menting. When they are properly sweated, grind and press them; and as soon as you have filled a cask, if a hogshead, which is one hundred and ten gallons, ferment it as follows; and if less, proportion the ingredients to your quantity. A Ferment for Cyder.—To one hogshead of cyder, take three pints of solid yeast, the mildest you can get; if rough, wash it in warm water, and let it stand till it is cold. Pour the water from it, and put it in a pail or can; put to it as much jalap as will lay on a sixpence, beat them well together with a whisk, then apply some of the cyder to it by degrees till your can is full. Put it all to the cyder, and stir it well together. When the ferment comes on you must clean the bung-holes every morning with your finger, and keep filling the vessel up. The ferment for the first five or six days will be black and stiff; let it stand till it ferments white and kind, which it will do in four- teen or fifteen days; at that time stop the ferment, otherwise it will impair its strength. To stop the Ferment.—In stopping this ferment, which is a very strong one, you must first rack it into a clean cask, and when pretty near full, put to it three pounds of coarse, red, scower- ing sand, and stir it well together with a strong stick, and fill it within a gallon of being full; let it stand five or six hours, then pour on it as softly as you can a gallon of English spirit, and bung it up close; but leave out the vent-peg a day or two. At that time just put it in the hole, and close it by degrees till you have got it close. Let it lay in that state at least a year; and if very strong cyder, such as stire, the longer you keep it the better it will be in the body; and when you pierce it, if not bright, force it in the following manner. - A Forcing for Cyder.—Take a gallon of perry or stale beer, put to it one ounce of isinglass, beat well, and cut or pulled to small pieces; put to it the perry or beer, and let it steep three or four days. Keep whisking it together, or else the glass will stick to the bottom, and have no effect on the liquor. When it comes to a stiff jelly, beat it well in your can with a whisk, and mix some of the cyder with it till you have made the gallon four; then put two pounds of brick rubbings to it, and stir it together with two gallons of cyder more added to it, and apply it to the hogshead; stir it well with your paddle, and shive it up close. The next day give it vent, and you will find it fine and bright. If you force perry, cut your isinglass with cyder or stale beer, for no liquor will force its own body. To cure Acid Cyder.—It is always to be observed, that even weak alkalies cure the strongest acid, such, for instance, as calcined chalk, calcined oyster or scallop-shells, calcined egg- shells, alabaster, &c. But if a hogshead can soon be drank, use a stronger alkali, such as salt of tartar, or salt of wormwood; but in using them you must always preserve their colour with lac, or else the alkali will turn the liquor black, and keep it foul. To one hogshead, take two gallons of lacº, and put to it one ounce and a half of isinglass, beat well, and pulled small; boil them together for five or six minutes; strain it, and when a stiff jelly, break it with a whisk, and mix about a gallon of the cyder wth it: then put three pounds of calcined chalk, and two pounds of calcined oyster-shells to it, whisk it well together with four gallons more of the cyder, and apply it to the hogs- head. Stir it well, and it will immediately discharge the acid part out at the bung. Let it stand one hour, then bung it close * Lac is milk, but the cream must be skimmed off it for use. 212 C Y N G Y G. DICTIONARY OF MECHANICAL SCIENCE. for five or six days; rack it from the bottom into a clean hogs- head, and apply one quart of forcing to it. If you use a strong alkali, put to the lac four ounces of salt of tartar, or salt of worm- wood; but the former is best, as it hath not the bitter taste in it which the wormwood has. : * - - To cure Oily Cyder.—The reason that cyder is sometimes oily, is owing to the fruit not being sorted alike; for the juice of fruit that is not ripe will seldom mix with ripe juice in fermentation. The acid part of one will predominate over the other, and throw the oily particles from it, which separation gives the liquor a disagreeable, foul taste; to remedy which, you must treat it in the following manner, which will cause the oily parts to swim at top, and then you may rack the liquor from its bottom and oil. To a hogshead, take an ounce of salt of tartar, and two ounces of half sweet spirit of nitre, mix them in a gallon of lac, and whisk them well together; apply it to the hogshead, bung it up, and let it stand ten or fifteen days; then put a cock within two inches of the bottom of the hogshead, and rack it. Observe when it runs low to look to the cock, lest any of the oily part should come, which will be all on the top, and will not run-out till after the good liquor is drawn off. - Put to the clean a quart of forcing, to raise it, and bung it close.—When you take out the oil and bottom, your cask must be well fired, otherwise it will spoil all the liquor that shall be afterwards put into it.' - - For Ropy Cyder.—The following remedy for ropy cyder must be proportioned with judgment to the degree of the disorder in the liquor. If the rope be stiff and stringy, you must use a larger quantity of the ingredients. If a hogshead be quite stiff and stringy, work it at least an hour with your paddle, then put to it six pounds of common alum, ground to a fine powder; work it for half an hour after, and bung it up close. This in a week will cut the rope, and bring it to a fine, thin, fluid state. Then rack it into a clean hogshead, and put to it one quart of forcing; stir them well in the hogshead, and bung it close up. . If but a thin rope, use a less quantity of the alum, and work it the same way. Cyders bad-flavoured.—Some cyders in keeping are apt to get reasty, through the ill quality of the fruit; and sometimes through the badness of the cask will get musty, or fusty. To remedy these evils, you must throw it in ferment, if its body is strong, with yeast and jalap, and let it ferment three or four days; which will throw off the greatest part of the taste; then stop the ferment. If a hogshead, put to it one pound of sweet spirit of nitre, and bung it up close. This will cure the bad flavour, if any be left, and likewise keep it from growing flat. To colour Cyder.—In many places, particularly where the soil is light, and the orchard lies rising, the juice of the fruit is nearly white, and though the cyder may be strong, it does not appear to be so by reason of its colour, which always preju- dices the buyer against it. - - - - Many people spoil a great deal of good cyder by boiling add mixing molasses with it, to give it a colour which not only gives it a bad red colour, but makes it muddy as well as bad- tasted. Others again will boil a large quantity of brown sugar, and mix with it, which gives it a colour indeed, though a light one; when two pounds of good sugar, properly used, is suffi- cient to colour ten hogsheads, as follows: Take two pounds of powder sugar, the whiter the sugar the farther it will go, and the better the colour will be. Put it in an iron pot or ladle; set it over the fire, and let it burn till it is black and bitter; then put two quarts of boiling hot water to it; keep stirring it about, and boil it a quarter of an hour after you have put the water to it. Take it off the fire, and let it stand till it is cold, then bottle it for use. Half a pint of this will colour a hogshead. Put to each half- pint, when you use it, a quarter of an ounce of alum ground, to set the colour.-See CIDER. + - CYDONIA, the Quince, so called from Cydon in Crete, which abounds with this fruit. The species are, 1. The oblonga, with an oblong fruit, lengthened at the bases. 2. The maliforma with oval leaves, woolly on the upper side. The most valuable is that called the Portugal quince, the pulp of which turns to a fine purple, and makes a good marmalade. * CYGNUS, is fabled by the Greeks to be the Swan, under the form of which Jupiter deceived Leda or Nemesis, the wife of Tyndarus, king of Laconia. Leda was the mother of Pollux and Helena, the most beautiful woman of her age, and also of Castor and Clytemnestra. The two former were deemed the offspring of Jupiter, and the others claimed Tyndarus as their father. According to another fable, Orpheus, the celebrated musician of antiquity, having been killed by the cruel priestess of Bacchus, the gods metamorphosed him into a Swan, and placed him among the stars by the side of his lyre. . . . . Boundaries and Contents.—Cygnus is situated in the Milky Way, and is bounded on the north by Draco, east by Lacerta and Pegasus, south by Vulpecula et Anser, and west by Lyra. There are eighty-one stars in this constellation, viz. one of the 1st or 2d magnitude, six of the 3d, twelve of the 4th, &c. The most brilliant star in Cygnus is called Deneb, whose right ascension is 308° 49' 19", ānd its descension 44° 38' 32" north. The greater part of this constellation never sets in lat. 51° north, and Deneb culminates at London, for the first day of every month, as in the following table : Meridian Altitude, 839 7" 32". - Culm. MoxTH. CU:.M. MoMTH. CULM MONTH. bo. mi. ho. mi. ho. mi. Jan. 2 0 A. May 6 0 M. Sept. 9 50 A. Feb. 11 40 M. June 3 55 M. Oct. 8 lo A. March 9 45 M. July 1 55 M. TNoy. 6 15 A. . April 7 45 M. Aug. 11 50 A. T}ec. 4 15 A. . CYLINDER, is a solid having two equal circular ends parallel to each other, and every plane section parallel to the ends is also a circle, and equal to them. Cylinders are either right or oblique. Fig. 1. Fig, 2. A Right CYLINDER, is that whose side is perpen- dicular to the plane of its base, as the figure ABCD fig. 1. An Oblique CYLINDER, is that whose side is not perpendicular, but oblique to the plane of its base, as L M N O, fig. 2. A right cylinder may be conceived to be generated by the revolution of a rectangle, as P B D Q, about one of its sides PQ, which remains fixed, and which is called. the axis of the cylinder. Or we may otherwise conceive it to be generated by carrying a right line parallel to itself, about the circumferences of two equal and parallel circles; which answers as well for the oblique, as for the right cylinder. . . . To find the Surface and Solidity of a Cylinder, whether right or oblique.—1. Multiply the circumference of its base by its length, and the product will be the area. 2. Multiply the area of its base by its perpendicular height, and the product will be the solidity. - - - CYLINDRIC, or CYLINDRICAL, any thing relating to the cylinder. CYLINDRIC Ring, is a solid which may be conceived, by supposing a cylinder to be bent round into a circular form, so as to return upon itself. To find the Surface and Solidity of a Circular Ring.—1. Multi ply the circumference of a perpendicular section of the ring, by half the sum of the inward and outward diameters, and that product again by 3’ 1416, and the last product will be the surface of the ring. 2. Multiply the area of a perpendicular section by the same quantities, and the last product will be the solidity. - - . - CYMATIUM, in Architecture, a member or moulding of the cornice, the profile of which is concave at the top and convex at the bottom. . . . . . CYMBAL, a musical instrument of antiquity. It was round, and made of brass like our kettle-drums, but smaller, and applied to a different use. - CYNARA, the Artichoke, a genus of the polygamia aequalis order, and of the syngenesia class of plants. There are four species, but only two are cultivated for use. The garden arti- choke, which is either the conical green-headed French arti- choke, or the globular-headed red Dutch artichoke ; and the cardoon, which is larger than the preceding. The former is. propagated by slips or suckers, and the latter by seed. G Y P G Y' P 213 DICTIONARY OF MECHANICAL SCIENCE, CYNICS, a sect of ancient philosophers, who valued them- selves upon their contempt of riches and state, arts and sci- ences, and every thing, in short, except virtue or morality. CYNIPS, a genus of insects of the order of hymenoptera, of a bright brown colour, and produced in the hard galls under the oak leaves, being deposited there by the gall-fly. The oak- bud cynips is of a shining green colour, and there are nineteen species of this insect. & tº CYPERUS, a genus of the monogynia order, in the tri- andria class of plants, ranking in the natural method under the 3d order, calamariae, of which there are fifty-three species, the principal of which are the round, the long sweet cyperus, and the papyrus. The long cyperus is used by perfumers and glovers. The papyrus is celebrated for its early use as paper. CYPHER, or CIPHer. To write in cypher denotes the art of communicating by writing in such a manner as shall be legible only to those who are acquainted with the rules by which the characters made use of are formed or disposed. It is principally used in diplomatic correspondence, or on other national affairs, such as those relating to the operations of war. As the nature of alphabetic writing, and the structure of lan- guages, necessarily imply certain indispensable habitudes of the letters and words, it often happens that the laws or condi- tions made use of for the sake of secrecy can be detected by skilful persons, and the secret by that means discovered. The art of discovering the sense of writings of the description here mentioned, is called decyphering. CYPRAEA, or Cow Rie, a genus of insects of the order of vermes testaceae. It is of the snail kind; and there are forty- four species, distinguished by the form of their shells, which are used as money in Bengal and on the coast of Guinea. CYPRESS. See CUPRESSU.S. tº CYPRINUS, a genus of fishes of the order of abdominales, of which there are thirty-one species, as, 1. The carp, found in the rivers and lakes of Polish Prussia, &c. Carp is a long- lived fish, and instances are related of some that have attained the age of 100 years. The carp is very cunning, and on that account is called the river fox. It is very shy in taking a bait, but in spawning time it is easily caught. In Prussia, carp are often kept some time out of water, and grow fat in their new element. They are suspended in a net in a cellar, and plunged. in water every four or six hours. 2. The barbel, a coarse fish, whose roe is so noxious as to produce vomiting, purging, and a swelling in those who unwarily eat of it. The barbel is about three feet long, and the dorsal fin is armed with a strong spine, with which it inflicts a dangerous wound. 3. The tench, reckoned a delicious food in this country, weighs generally 4 or 5lbs. and is thick and short. The colour of the back is dusky, but the head, sides, and belly are greenish with a mix- ture of gold. 4. The gudgeon, found in gentle streams, seldom weighs more than half a pound. 5. The bream, which inhabits lakes or the deep parts of still rivers, is an insipid fish. 6. The roach is a common river fish, never exceeding five pounds. 7. The dace, also common, and a great breeder, is often seen in the Summer frolicking on the water. The general weight is less than 21bs. 8. The cephalus or chub, is a coarse bony fish, that frequents the deep holes of rivers. 9. The bleak, is common in many rivers. At some seasons they are so much agitated as to be called mad-bleak by the fishermen. It is supposed that this is occasioned by a hair-worm, which attacks them, and of which they die. Artificial pearls are made of the scales of this fish, and also of those of the dace. The usual length of the bleak is two inches. 10. The gold fish, a small beautiful spe- cies, domesticated in China, and much valued as an ornament for courts and gardens. The gold and silver fish were intro: duced into England generally in 1723. D. ID A M D, the fourth Letter of the Alphabet, and as a numeral denoting 500, with a dash over it, T) 5000. In abbreviation it has various significations, as D. D. doctor in divinity; M. D. doctor in medicine. In Music, D marks in thorough bass what the Italians call descanto, denoting that the treble ought to play alone, as T does the tenor, and B the bass. DC means the abbreviation of de capo, or from the head. DAEMON, a name given to certain spirits, or genii, which, it is said, appeared to men. DAIRY, in rural affairs, a place appointed for the manage- ment of milk, and the making of butter, cheese, &c. Dairy- houses are to be kept perfectly clean; and lattices are to be preferred to windows; and if their situation can be fixed beside a spring or current of water, it is to be preferred. The proper receptacles for milk are earthen pans, or wooden yats, and lead should not be used on any account, as it is highly poisonous, unless the greatest care be used to scald it daily. DAMAGE, in Law, is generally understood of a hurt or hinderance attending a person’s estate; but in Common Law, it is a part of what the jury are to inquire into, relative to the plaintiff or defendant. DAMAGE faisant, is where the beasts of another come upon a man's land and spoil his corn or grass, in which case the owner may impound them till satisfaction be obtained. I5AMASK, a sort of silken stuff, both in warp and woof; or with the warp silk, and the woof thread; or all thread, or all wool. And Damasheening is the art of beautifying iron, or steel, by inlaying it with gold, or silver wire, às in sword blades, guards, and gripes, locks of pistols, &c. Were the artists of Britain to turn their attention to this subject, they might soon rival all other countries in the world in damaskeen- ing steel. e gº º i)AMPS, noxious exhalations issuing from the earth, and which almost instantly prove fatal to those who breathe them. D A Y We allude here chiefly to coal mine damps, called choke and fire damps; the former is carbonic acid gas, generally prevalent in wastes, or neglected works; the latter is hydrogen gas, or inflammable air. See Safety Lamp. DARK RAYs, in Philosophy, are certain emanations from the sun, that have been recently discovered, which are mot per- ceptible to our eyes, and are only manifested by their effects on the thermometer. Thus when the rays of the sum are refracted by a glass prism, and form the coloured spectrum upon any surface, a thermometer placed beyond the spectrum is elevated by the heat of certain rays, or emanations, which are by no means visible; and which have thence been denominated calorific rays. DATA, in Mathematics, denote certain quantities which are given or known, and by means of which other quantities, which are unknown, are to be determined. Euclid, in his book of “Data,” uses this term to denote such spaces, lines, angles, &c. as are given, or to which others may be found equal. DATE, in Law, the description of the day, month, year of our Lord, and year of the king in which a writing is made. In writings of importance, the date should be in words at length. . An ante-date is that prior to the real time when the instrument was signed. ... A post-date is that which is posterior to the real time. . . DAY, in Astronomy, is that portion of time which elapses between two successive transits of the sun over the same meri- dian ; and the time is reckoned from noon to noon, and consists of twenty-four hours. This is called a natural day, being of the same length in all latitudes. The artificial day is the time elapsed between the sum’s rising and setting, and is variable according to the different latitudes of places. A mean Solar Day is measured by equal motion, as by a clock or timepiece, and consists of twenty-four hours. There are, ". the course of a year, as many mean solar days as there l 344 D E A D. A. V. DICTIONARY OF MECHANICAL SCIENCE. are true solar days, the clock being as much faster than the sun-dial on some days of the year, as the sun-dial is faster than the clock on others. Thus the clock is faster than the sun-dial from the twenty-fourth of December to the fifteenth of April, and from the sixteenth of June to the thirty-first of August; but from the fifteenth of April to the sixteenth of June, and from the thirty-first of August to the twenty-fourth of Decem- ber, the sun-dial is faster than the clock. When the clock is faster than the sun-dial, the true solar day exceeds twenty-four hours; and when the sun-dial is faster than the clock, the true. solar day is less than twenty-four hours; but when the clock and the sun-dial agree, viz. about the fifteenth of April, six- teenth of June, thirty-first of August, and twenty-fourth of December, the true solar day is exactly twenty-four hours. Days of the Week.-These are Sunday, Monday, Tuesday, Wednesday, Thursday, Friday, and Saturday. The Nautical Day commences, either by observation or account, when the sun is on the meridian, which is generally sup- posed to be our 12 o'clock at noon on shore. At that moment, the officer of the watch, or more commonly the master of the ship, orders the marine sentinel to turn a half-hour sand glass, which he has always in charge, which has been previously run out, and strike eight bells forward; which is accordingly done, and the dinner is piped. No sooner is this glass run out, than the sentinel calls, “Strike the bell one, forward;” and again turns it, when the grog is immediately piped. When it runs out a second time, he again calls, “Strike the bell two, for- ward;” which is no sooner done, than the boatswain's mate calls the afternoon watch. Thus he proceeds until he comes to the eighth bell, which is no sooner struck, than the watch expires, and the grog is again piped. Previous to this, how- ever, in order to relieve the quartermaster, the helmsman, the look-out at the mast head, and the sentinel at the glass, an individual of each of these classes of the watch below, goes, when the seventh bell is struck, to the purser's steward, gets his quartern of grog unmixed, takes his supper, and is ready, as soon as the 8th strikes, to relieve his man with the rest of the watch. All hands now take supper; and when one bell again strikes, the first dog watch is called. This is only a watch of two hours; and accordingly when the 4th bell has struck, the second dog watch is called, which lasts other two hours, and brings the supposed time pretty accurately to our eight o'clock at night. By this time, however, the hammocks having been piped down, the watch relieved generally retires to rest. The watch on deck, therefore, execute all the neces- sary duties of the ship until their 8th bell is struck; when the middle watch is called; and these again are relieved in the same time by the morning watch, who do the ship's duty during other eight bells, which brings the time to our eight o'clock in the morning, when breakfast is always piped. As usual at one bell, the forenoon watch is called, who do the duties of the deck while the watch below are fumigating or scrubbing the lower deck, or probably mending their clothes; and thus they con- tinue until the observation of the sun at noon is again taken, if the weather is favourable, and any necessary correction made on the time lost or gained. When the eighth bell is once more struck, the day at sea is completed, the glass is turned to com- i. a new one, the dinner is piped, and the watch called as efore. DAY's of Grace, in Commerce, are those allowed for the pay- ment of a bill of exchange after the sum becomes due. In England they are three. DAY'S WORK, the reckoning or account of a ship's course or distance run during 24 hours, or from noon to noon, accord- ing to the rules of TRIG oxoMetRY. DAVIT, a strong beam of timber used as a crane, whereby to hoist the flukes of the anchor to the top of the bow, without injuring the planks of the ship's side as it ascends; an opera- tion which, by seamen, is called fishing the anchor; the lower end of the davit rests on the fore chains, the upper end being pro erly sectºred by a tackle from the mast head ; upon the other end is hung a large block, through which a strong rope is reeved, called the fish-pendant, to whose outer end is fitted a large hook, and to its inner end a tackle ; the former is called the fish-hook, the latter the fish-tackle, The anchor being first catted, the fish-hook is fastened on its flukes, and is, by means of the fish-pendant and tackle, drawn up sufficiently high upon the bow to be made fall lºy the shank-painter. Thus the davit, according to the sea phrase, is employed to fish the anchor. There is also a davit. of a smaller kind, occasionally fixed in the longboat, and, with the assistance of a small windlass, used to weigh the anchor by the buoy-rope, &c. DEACON, one of the three holy orders of the church, being that next below the priesthood. - DEAD EYE, or DeAD MAN’s EYE, a sort of round flattish wooden block encircled with a rope, or with an iron band, and pierced with three holes through the flat part, in order to receive a rope called the laniard, which corresponding with three holes in another dead eye, creates a purchase employed for various uses, but chiefly to extend the shrouds and stays, otherwise called the standing rigging. In order to form this purchase, one of the dead eyes is fastened in the upper link of each chain on the ship’s side, which is made round to receive and encompass the hollowed outer edge of the dead eye. After . this the laniard is passed ultimately through the holes in the upper and lower dead eyes, till it becomes sixfold, and is then drawn tight by the application of mechanical powers. In mer- chant ships they are generally fitted with iron plates, in the room of chains. The dead eyes used for the stays have only one hole, which, however, is large enough to receive ten or twelve turns of the laniard; these are generally termed Hearts. The crowfeet Dead Eyes, are long cylindrical blocks, with a number of small holes in them, to receive the legs, or lines, of which the crow foot is composed. DEAD LIGHTS, strong wooden ports made exactly to fit the cabin windows, in which they are fixed on the approach of a storm, the glass frames being taking out, which would other- wise be shattered by the violence of the waves, and let great quantities of the water pour into the ship. DEAD RECKONING, the judgment or estimation which is made of the place where a ship is situated, without any obser- vation of the heavenly bodies; it is discovered by keeping an account of the distance she has run by the log, and of her course steered by the compass, and by rectifying these data by the usual allowances for drift, leeway, &c. according to the ship's known trim; this reckoning is, however, always to be corrected as often as any good observation of the sun can be obtained. f DEAD RISING, or Rising LINE of the floor, those parts of a ship's floor or bottom throughout her whole length, where the floor timber is terminated on the lower futtock. DEAD ROPES, are those which do not run in any block. DEAD WATER, the eddy of water which appears like little whirlpools closing in with the ship's stern as she sails through it. DEAD WOOD, in "Naval Architecture, certain blocks of timber laid upon the keel, particularly at the extremities afore and abaft, where these pieces are placed upon each other to a considerable height, because the ship is there so narrow as not to admit of the two half timbers, which are therefore scored into this dead wood, when the angle of the floor timbers gradually diminishes as approaching the stem and stern post. In the fore part of the ship, the dead wood generally extends from the stemson, upon which it is scarfed, to the loof frame ; and in the after end from the sternpost, where it is con- fined by the knee to the after balance-frame. It is oonnected to the keel by strong spike nails. The dead wood afore and abaft is equal in depth to two-thirds of the depth of the keel, and as broad as can be procured, so as not to exceed the breadth of the keel. . . DEAD WORKS, all that part of the ship which is above water when she is laden. The same as UPPER. WoRK, BEAFNiSS, the want of the sense of hearing, arising either from an obstruction or a compression of the auditory nerves, or from some collection of mattor in the cavities of the inner ear, or from the auditory passage being stopped by some hardened excrement; or, lastly, from some excrescence, a 8welling of the glands, or some foreign body introduced within the ears. Persons born deaf are also dumb, * DEAL, a plank of fir, made by sawing the trunk of the tree longitudinally, Deals are hardened by throwing them into salt water as soon as they are sawed, and keeping them therein Some days, and then drying them in the sun. D is 0. D E 6 DICTIONARY OF MECHANICAL SCIENCE. 215 bEAN, an ecclesiastical dignitary next to the bishop, and head of the chapter in a cathedral church. There are deans also who have no chapters, as the dean of Battle, the dean of Bocking, &c. Rural deans have no judicial authority, but a right of visiting churches within their district, and reporting the condition of the same to the ordinary. DeAN and Chapter, are the bishop's council to assist him in the affairs of religion, and to assent to every grant which the bishop shall make to bind his successors. As a deanery is a spiritual dignity, hence a man cannot be a dean and preben- dary of the same church. DEATH, physically, the cxtinction of animal life. In Law, there is a natural death and a civil death; the former where a person actually dies, the latter where he is adjudged to be so in law. Thus if a person, for whose life an estate is granted, is absent seven years, and there is no proof of his being living, he shall be accountcd as dead. DEATH-WATCH, a small insect which makes a ticking noise like the beating of a watch. There are two species, one of a dark brown colour, spotted, having pellucid wings under the vagina, a cap on the head, and two antennae proceeding from beneath the eyes. The noise which it makes is a signal between the male and female. The second kind is a small grayish insect, much like a louse when viewed with the naked, unassisted eye. DEBENTURE, a Custom-house certificate delivered to the exporter of goods, by virtue of which he is entitled to a bounty or drawback. DEBT, NATIONAL, the engagement entered into by a govern- ment, to repay at a future period money advanced by indi- viduals for the public service, or to pay the lenders an equi- valent annuity. National debts have arisen from the necessity of obtaining larger sums of money than could be raised at the time they were wanted by direct contributions; and often, when it would have been absolutely impossible to raise the requisite sum if a heavy tax had been imposed, and strictly levied, it has been deemed more prudent to avoid the evils attendant on such a measure by the less obnoxious expedient of a loan. In most countries, the subordinate governors, to whom is generally consigned the task of providing for the public expenses, being desirous of popularity, have shewn a great predilection for this mode of obtaining money, as it enables them to support a profuse expenditure, without ap- pearing to oppress the people in so great a degree as they otherwise must: the system of getting into debt, or the fund- ing system, as it is generally called, from particular funds being usually appropriated for payment of interest on the debts contracted, has therefore been adopted by most of the states of Europe, by many of the colonies, and by the American republics.-WAT KINs' Cyclopaedia. DECACHORDON, a musical instrument like the harp with ten strings, called by the Hebrews nasur. DECAGON, a plane geometrical figure, of ten sides and ten angles. When all the sides and angles are equal, it is a regular decagon, and may be inscribed in a circle ; otherwise not. If the radius of a circle, or the side of the inscribed hexa- gon, be divided in extreme and mean proportion, the greater segment will be the side of a decagon inscribed in the same circle. And, therefore, as the side of the decagon is to the radius, so is the radius to the sum of the two. DECEMBER, THE BotANICAL KALENDAR Fort, instructs us that the gardener's operations are chiefly of the laborious kind; but long nights and short days give him ample leisure for study, unless he be of the slovenly tribe of gardeners, whose minds resemble their gardens, and are known rather by the excel- Hence and growth of the weeds, than by order, regularity, pro- gress, and scientific reputation. In the Kitchen Garden, this month sow peas, beans, and radishes; but consider the result uncertain. Protect beans, transplant cabbages; earth up peas and beans ; cover their stems with ashes, sawdust, or old tan. Tie up endive ; weed and hoe ; tie up esculents, as borecoles; destroy slugs, snails, mice ; and fill the ice-house, In the hardy Fruit Department, we plant the apple, pear, gooseberry, currant, &c. in mild weather ; and all trees not pruned in November are now to be pruned. In the routine of culture, trench, dig, and ridge up in dry weather. Exhausted soils must now be recruited; larvae of moths must be destroyed; and the temperature of the fruit cellars must be kept from 30° to 40°. - In the culinary Hot-house Department, sow small sallads, give abundance of air in dry weather, but protect in frosts. Begin to force asparagus, prepare cucumber beds; keep a steady heat in the pinery; and let the forcing houses be regularly attended to. Little is done in the flower department this month, except in a liberal use of ashes, tan, &c. to bulbs, hydrangeas, &c. Attend to alpines, florists’ flowers, annuals, &c. In the green- house the lowest temperature must be 42°, the highest 46°. The dry stove may average from 45° to 50°. But the back stove must average from 55° to 58°. s * In the Pleasure Ground and Shrubbery, plant, prune, protect according to the weather; repair walks, roll them; sweep and cléan lawns, lay down turf; and fell all trees that are to be removed as useless, or for their timber and bark. DECEMVIRI, ten magistrates chosen yearly at Rome to govern the commonwealth instead of consuls. DECIDUOUS, in Botany, a term expressive of the second stage of duration in plants, but susceptible of different senses, according to the particular part of the plant to which it is applied. A leaf is said to be deciduous which drops in autumn; petals are deciduous which fall off with the stamina and pistil- lum; and this epithet is applied to such flower-cups as fall after the expansion, and before the dropping of the flower. Most plants in cold and temperate climates shed their leaves yearly. This happens in autumn, and is generally announced by the flowering of the common meadow saffron. The term is only applied to trees and shrubs; for herbs perish down to the root every year, losing stem, leaves, and all. All plants d6. not drop their leaves at the same time. Among large trees, the ash and walnut, although latest in unfolding, are soonest divested of them : the latter seldom carries its leaves above five months. On the oak and horn-beam the leaves die and wither as soon as the cold commences; but remain attached to the branches till they are pushed off by the new ones, which unfold themselves the following spring. These trees are doubt- less a kind of evergreens; the leaves are probably destroyed only by cold; and, perhaps, would continue longer upon the plant, but for the force of the spring-sap, joined to the moisture. With respect to the deciduous trees, the falling off of the leaves seems principally to depend on the temperature of the atmosphere, which likewise serves to hasten or retard the appearance in question. An ardent sum contributes to hasten the dropping of the leaves. Hence, in hot and dry summers, the leaves of the lime-tree and horse-chesnut turn yellow about the ist of September; whilst, in other years, the yellowness does not appear till the beginning of October. Nothing, how- ever, contributes more to hasten the fall of the leaves than im- moderate cold or moist weather in autumn ; moderate droughts, on the other hand, serve to retard it. It deserves to be re- marked, that an evergreem tree grafted upon a deciduous, determines the latter to retain its leaves. This observation is confirmed by repeated experiments, particularly by grafting the laurel, or cherry-bay, an evergreen, on the common cherry; and the ilex, or evergreen oak, on the oak,-WAT KINs' Cyclopædia DECIES TANTUM, in Law, a writ that lies against a juror, who has been bribed to give his verdict. TECIMAL, ARITHMRT ic, (Decimal Tenths,) in a general sense, denotes the common arithmetic, in which we count by periods of tens; and is otherwise, and more properly, called Benary Arithmetic, to distinguish it from the Binary, Duode- nary, and other scales of arithmetic. Decim Al Fraction, is a fraction having always some power of 10 for its denominator, which consists of either 10, 100, 1000, &c., demoting the number of equal parts into which the integer or whole is supposed to be divided, as #, ſº, tºº, &c. But, for the sake of brevity, the numerator only is expressed, like a whole number with a point on the left of it, as 2, '02, '002, &c. and which must always consist of as many figures as there are ciphers in the denominator; the places between the significant figures and the point being supplied with ciphers, when neces- 216 D E C . D E C DICTIONARY OF MECHANICAL SCIENCE. sary, as above. . Consequently, the same number of figures on the right of the decimal point, has always the same denomina- tor. Thus, the denominator of the fractions ‘5000, 0746, '0005, is 10000. And hence, it appears, that the value of a decimal fraction is not altered by ciphers on the right hand; for 5000 (or §6) when reduced to its lowest terms is the same as ‘5, each being equal to #. In mixed numbers the decimals are separated from the integers by a point, thus, 25rº is written 25-02. It is also evident, that the value of decimals decreases in the same tenfold proportion from the point towards the right hand, as that of integers increases towards the left. DECKER, relates to the rate of a ship of force, as a two- decker, a three-decker, i.e. carrying two entire tiers or ranges of cannon, or three such tiers. DECKS, the planked floors of a ship, which connect the sides together, and serve as different platforms to support the artil- lery and lodge the men, as also to preserve the cargo from the sea and rain. As all ships are broader at the lower deck than on the next above it, and as the cannon thereof are always heaviest, it is necessary that the frame of it should be much stronger than that of the others; and for the same reason, the second or middle deck ought to be stronger than the upper deck or forecastle. - - - !' Ships of the first and second rate are furnished with three whole decks, reaching from the stem to the stern, besides a forecastle and a quarter deck, the former extending aft from the stem to the belfry, and the latter forward from the stern to the mainmast, a vacancy being left in the middle, which opens to the upper deck, and forms what is called the waist; there is yet another deck, above the hinder part of the quarter deck called the poop, which also serves as a roof for the captain's cabin or couch; and another deck below the lower gun-deck called the orlop, whereon the cables are coiled and the sails Stowed, &c. Other ships of the line, with 50-gun ships, and Some of 40 guns, have two gun-decks and a quarter deck, a forecastle, a poop, and orlop, Frigates and sloops have one gun-deck, a half deck, and forecastle, with a spar deck below to lodge the crew, but no poop ; brigs, cutters, and such small vessels, have no half deck or forecastle, and are then said to be flush fore and aft; the decks are formed of, and sustained by, the beams, the clamps, or water-ways, the carlings, the ledges, the knees, and two rows of small pillars called stan- chions, &c.. See those articles. The number of beams by which the decks of ships are supported, is often very different, accord- ing to the practice of different countries; the strength of the timber of which the beams are framed, and the services for which the ships are calculated. The deck which contains the train of a fire-ship is furnished with an equipage peculiar to itself, a description of which will be found under the article FIRE-SHIP. Flush deck, or deck ſlush fore and aft, implies a continued floor laid from stem to stem, upon one line, without any stops or intervals, Half deck, the under part of the quar- ter deck of a ship of war, contained between the foremost bulk head of the cabin or wardroom, and the break of the quar- ter deck. ... In the colliers of Northumberland, the steerage itself is called the half deck, and is usually the habitation of the ship's crew. The main deck is that part of the upper deck which extends from the break of the forecastle to the break of the quarter-deck; also called the waist. - - DECLARATION, in Law, a written exposition of the matter of complaint, made by the plaintiff against the defendant. DECLINATION OF THE SUN, of a Star, or a Planet, is its distance from the equinoctial, northward or southward. when the Sun is in the equinoctial, he has no declination, and enlight- ens half the globe from pole to pole. As he increases in north declination he gradually shines farther over the north pole, and leaves the south pole in darkness; in a similar manner, when he has south declination he shines over the south poie, and leaves the north pole in darkness: 23° 28′ is the sun's nearest declination north or south. The declination of any heavenly body, as of a star, may be easily found by the follow. ing rule: Take the meridian altitude of the Star, at any place where the latitude is known; the complement of this is the zenith distance, and is called north or south, as the star is north or South at the time of observation. Then, 1. When the lati- tude of the place, and zenith distance of the star, are of differ- ent kinds, namely, one north and the other south, their differ- ence will be the declination; and it is of the same kind with: the latitude, when that is the greatest of the two, otherwise it. is of the contrary kind. 2. If the latitude and the zenith dis- tance are of the same kind, i.e. both north, or both south, their sum is the declination; and it is of the same kind with the latitude. Accurate tables of the sun's declination are published regularly in the nautical almanacks. . . Circles of Declination, are great circles of the sphere. passing through the poles of the world, on which the declination is measured. - - - Parallels of Declin AtjoN, are small circles of the sphere parallel to the equator. - - - Parallar, or Itefraction of Declination, is such an arch of a meridian as is equal to the change produced in the declina- tion by parallax or refraction, respectively. Declin Atio N of a Vertical Plane or Wall, in Dialing, is an arch of the horizon, comprehended either between the plane and the prime vertical, when it is counted from east to west, or between the plane and the meridian, when it is counted from north to south. - DECLINATOR, an instrument for determining the declina- tion or inclination of reclining planes. DECLINERS, or Declining DIALs, are those which cut either the plane of the prime vertical circle, or plane of the horizon, obliquely. - DECLIVITY, a sloping or oblique descent. DECOCTION, in Pharmacy, the extracting of the virtues of simples and other drugs by boiling. - DECOMPOSITION, in Chemistry, the separation or dis- union of the constituent parts of bodies. - DECORATION, in Architecture, any thing that adorns and enriches a building, church, triumphal arch, &c. as the orders of architecture, paintings, vases, festoons, scenes, &c. DECOUPLE, in Heraldry, the same as uncoupled, or parted. DECOY, among fowlers, a place made for catching wild- fowl. A decoy is generally made where there is a large pond surrounded with wood, and beyond that a marshy and uncul- tivated country: if the piece of water is not thus surrounded, it will be attended with noises and other accidents which may be expected to frighten the wild-fowl from a quiet haunt, where they mean to sleep in the day-time in security. If these noises or disturbances are wilful, it has been held that an action will lie against the disturber. As soon as the evening sets in, the decoy rises, and the wild-fowl feed during the night. If the evening is still, the noise of their wings during their flight is heard at a very great distance, and is a pleasing, though rather melancholy, sound. The decoy ducks are fed with hemp-seed, which is thrown over the screens in small quantities, to bring them forwards into the pipes or canals, and to allure the wild-fowl to follow, as this seed is so light as to float. There are several pipes, as they are called, which lead up a narrow ditch that closes at last with a funnel-net. Over these pipes (which grow narrower from their first entrance) is a continued arch of netting sus- pended on hoops. It is necessary to have a pipe or ditch for almost every wind that can blow, as upon this circumstance it depends which pipe the fowl will take to ; and the decoy-man. always keeps on the leeward side of the ducks, to prevent his scent reaching their sagacious nostrils. All along each pipe, at intervals, are placed screens made of reeds, which are so situ- ated that it is impossible the wild-fowl should see the decoy- man before they have passed on towards the end of the pipe, where the purse-net is placed. The inducement to wild-fowl to go up one of these pipes is, because the decoy ducks, trained to this, lead the way, either after hearing the whistle of the decoy-man, or enticed by the hemp-seed; the latter will dive under water, whilst the wild-fowl fly on, and are taken in the purse. It often happens, however, that the wild-fowl are in such a state of sleepiness and dozing, that they will not follow the decoy ducks. Use is then generally made of a dog that is taught his lesson: he passes backwards and forwards between the reed screens (in which are little holes, both for the decoy- man to see, and the little dog to pass through ;) this attracts the eye of the wild-fowl, who, not choosing to be interrupted, advance towards the small and contemptible animal, that they D E F D E G 217 DICTIONARY OF MECHANICAL SCIENCE. may drive him away. The dog all the time, by the direction of the decoy-man, plays among the screens of reeds, nearer and nearer the purse-met; till at last, perhaps, the decoy-man appears behind a screen, and the wild-fowl not daring to pass by him in return, nor being able to escape upwards on account of the net-covering, rush on into the purse-net. Sometimes the dog will not attract their attention if a red handkerchief, or something very singular, is not put about him.—WAT KINs' Cyclopædia. - DECOY, in Military affairs, a stratagem to carry off the enemy's horses in a foraging party, or from pasture. The word is also used to denote a stratagem employed by a small ship of war, to betray a vessel of the enemy within reach. DECREMENT, in Heraldry, the wane of the moon from the full to the new, and when borne in coat armour, faces to the left side of the escutcheon, as that luminary does to the right side when in the increment. . . DECREPITATION, in Chemistry, a term applied to the crackling noise of salt; exposed to heat, by which they are quickly split. It takes place in those salts that have little water of crystallization, the increased temperature converting that small quantity into vapour, by which the crystals are suddenly burst. Common salt affords a good example of decrepitation, and when used as a flux should be previously decrepitated. DEDIMUS PotestATEM, in Law, a commission granted to one or more persons, to forward and despatch some act apper- taing to a judge, or some court. - w DEED, a written contract sealed and delivered. It must be written before the sealing and delivery, otherwise it is no deed; and after it is executed by the parties, nothing can be added, and therefore, if a deed is sealed and delivered with a blank left for the sum, which the obligee fills up after sealing and delivery, this will make the deed void. DEEP SEA-LINE, or DIP SeA-LINE, in the sea-language, a small line to sound with ; some a hundred and fifty fathoms long, with a plummet hollow at the head, and tallow put into it, to bring up stones, gravel, sand, shells, and the like, from the bottom, to know the differences of the ground. | DEEP WAISTED, the distinguishing fabric of a ship's decks, when the quarter deck and forecastle are elevated from four to six feet above the level of the upper or main deck, so as to leave a vacant space, called the waist, on the middle of the upper deck. - - DE FACTO, something actually fact, in contradistinction to de jure, where a thing is only so in justice, as a king defacto is a person in possession of a crown, but without a legal right to the same; and, a king de jure is he who has just right to the crown, though he is out of possession. DEFAMATION, the offence of speaking slanderous words of another; and where any person circulates any report inju- rious to the credit or character of another, the party injured may bring an action to recover damages proportioned to the injury he has sustained; but it is incumbent upon the party to prove that he has sustained an injury, to entitle him to damages. In some cases, however, as for words spoken which, by law, are in themselves actionable, as calling a tradesman a bank- rupt, a cheat, or swindler, &c. there is no occasion to prove any particular damage, but the plaintiff must be particularly attentive to state words precisely as they were spoken, other- wise he will be monsuited. DEFEASANCE, in Law, a condition relating to a deed ; as to a recognizance or statute, which being performed by the recognizor, the deed is defeated, and made void, as if it had never been done. - DEFENCE, in Law, a plea made by the defendant after the plaintiff's declaration, viz. that he defends all the wrong, force, and damages, where and when he ought, &c. DEFENDER of THE FAITH, a peculiar title given to the king of England by pope Leo the Tenth, to king Henry the Eighth, for writing against Martin Luther in behalf of the Church of Rome, then accounted domicilium fidei catholicae. DEFICIENT NUMBERs, in Arithmetic, those whose parts or multiples added together fall short of the integer, of which they are the parts; such is 8, its parts, 1, 2, 4, making only 7. DEFILE, in Military affairs, a narrow passage through which a company of horse and foot can pass only by making a small front, so that the enemy may take an opportunity to charge them with so much the more advantage, as those in the front and rear cannot come to the relief of one another. DEFINITION, an enumeration or specification of the simple ideas of which a compound idea consists, in order to ascertain its nature and character. DEFINITION, in Rhetoric, a short comprehensive explana- tion.—The special rules for a good definition are, 1. It must be adequate, that is, it must agree to all the particular species or individuals included under the same idea. 2. It must be pro- per, and peculiar to the thing defined. These rules being observed, will render a definition reciprocal with the thing defined, that is, the definition may be used in its place; or they may be mutually affirmed concerning each other. 3. A defini- tion should be clear and plain; no word should be used which has any difficulty in it. 4. A definition should be short, without tautology or superfluous words. , 5. Neither the thing defined, nor a synonymous name, should make any part of the defini- tion. See the author's GRAMMAR OF LOGIC and INTELLECTUAL Philosophy. - DEFLAGRATION, in Chemistry, the act of burning two or more substances together, as charcoal and nitre. DEFLECTION, the turning any thing aside from its former course by some adventitious or external cause. The word is often applied to the tendency of a ship from her true course, by currents, &c. which deflect or turn her out of her right Way. DeFlection of the Rays of Light, is a property which Dr. Hook observed in 1674-5, and read an account of before the Royal Society, March 18, the same year. He says, he found it different from both reflection and refraction; and that it was made towards the surface of the opacous body perpendicularly. This is the same property which Sir Isaac Newton calls inflec- tion. It is called by others diſfraction. DEFLECTIVE Forces, are those forces which act upon a moving body in a direction different from that of its actual course, in consequence of which the body is deflected, or turned, or drawn aside, from the direction in which it is mov- ing. Such is the attractive-force of the sun upon the earth in its orbit. . . DEFOLIATION, in Botany, the fall of the leaves; a term opposed to frondescentia, the annual renovation of the leaves, produced by the unfolding of the buds in spring. Most plants in cold and temperate climates shed their leaves every year; this happens in autumn, and is generally announced by the flowering of the common meadow saffron. The term is only applied to trees and shrubs; for herbs perish down to the root every year, losing stem, leaves, and all. 2, 4 DEFORCEMENT, in Law, the casting any one out of his land, or a withholding of lands and tenements by force from the right owner. DEGLUTITION, in Medicine, the act of swallowing the food, performed by means of the tongue driving the aliment into the oesophagus, which, by the contraction of the sphincter, protrudes the contents downwards. DEGRADATION, in Painting, expresses the lesseming the appearance of distant objects in a landscape, in the same man- ner as they would appear to an eye placed at that distance from them. - DEGREE, in Algebra, a term applied to equations, to dis- tinguish the highest power of the unknown quantity. Thus, it the index of that power be 3 or 4, the equation is respectively of the 3d or 4th degree. DEGREE, in Geometry or Trigonometry, is the 360th part of the circumference of any circle. Every circle being considered as divided into 360 parts, called degrees, which are marked by a small 9 near the top of the figure, thus, 45° is 45 degrees. The degree is subdivided into 60 smaller parts, called minutes, the minute into 60 others, called seconds; the second into 60 thirds, &c. Thus 450 12' 20", are 45 degrees, 12 minutes, 20 seconds. ſº The magnitude or quantity of angles is accounted in degrees; for because of the uniform curvature of a circle in all its parts, equal angles at the centre are subtended by equal arcs, and by similar arcs in peripheries of different diameters; and an angle is said to be of so many degrees as are contained in the are of any circle comprehended between theſegs of the angle, and having e 3 K 218 D E M D E G DICTIONARY OF MECHANICAL SCIENCE. the angular point for its centre. Thus we say, an angle of 90°, or of 45°24'. It is also usual to say, such a star is elevated so many degrees above the horizon, or declines so many degrees from the equator; or such a town is situated so many degrees of latitude or longitude. A sign of the ecliptic or zodiac contains 30 degrees. - DeGRee of Latitude, is the space or distance on the meridian through which an observer must move, to vary his latitude by one degree, or to increase or diminish the distance of a star from the zenith by one degree; and which, on the supposition of the perfect sphericity of the earth, is the 360th part of the meridian. The quantity of a degree of a meridian, or other great circle, on the surface of the earth, is variously determined by different observers, and the methods made use of are also various; and, therefore, without entering into all the histories of this undertaking, we shall present our readers with the following - TABLE of the different Lengths of a Degree, as measured in various Parts of the Earth, the Time of its Measurement, the Latitude of its Middle Point, &c. - Extent in Eng- DATE. LATITUDE. lish Miles & MEASURES. COUNTRIES. ecimals. 1525 |490 204' N,"| 68.763 |M. Fernel ..... . | France. 1620 |52 4 N. 66° 91 Snellius . . . . . . . . . Holland. . 1635 |53 15 N. : 69-545 | Norwood . . . . . . England. 1644 75-066 Riccioli ........ [Italy. 1669 $ 68-945 Picard . . . . . . . . 1718 } 49 22 N. jià è. ... }|France. 1737 ||66' 20 N. 69°403 || Maupertuis, &c... Lapland. mo || | | #: ; Cassinisiacaille France. - 68.751 Juan and Ulloa. . R 1744 || 0 0 } 68-732 | Bouguer . . . . . . . Peru. 68-713 | Condamine... . . . $ 1752 |33 18; S. 69.076 La Caille . . . . . . : * * 1755 43 0 N. 68.998 |Boscovich. . . . . . } |Ital 1764 |44 44 N. 69-061 |Beccaria....... ; *. 1766 (47 40 N. 69-142, Leisganig ...... Germany. 1768 (39 12 N. 68-893 | Mason and Dixon l America. 1802 |51 29.54%N. 69°146 |Lt.-Col. Mudge. England. 1803 |66 20% N. 69292 Swanberg, &c... Lapland. 12 32 N. | 68-743 | Lambton ... . . . . . Misore. 1808 144 52} N. | 68.769 |Biot, Arago, &c. | France. ELLIPticities of THE EARTH, expressed in Parts of its Equatorial Diameter. DeGREE of Longitude, is the space between two meridians that make an angle of 1° with each other at the poles; the quantity or length of which is variable, according to the lati- tude, being every where as the cosine of the latitude, viz. as the cosine of one latitude is to the cosine of another, so is the Iength of a degree in the former latitude to that in the latter, on the supposition that the earth is spherical. But taking the earth as a spheroid, the degree of longitude may be found in any given latitude L, by saying, 1. As the equatorial diameter is to the polar, so is tang. 90° — L, to tang. of an angle A ; then, 2. As radius is to sine of A, so is the length of a degree of the A UTHORS. Ellipticities. PRINCIPLES. a . Huyghens, i R - it e º 'º º 375 - - ºf gº or " 1: r Newton, . . . . . . . sh; 5 Theory of gravity. a # ar t - Maupertuis, &c. Tig Mensuration of arcs. Swanberg, . . . . . .] gºss Clairault,... . . . . . . Tºg: Rotatory motion. # , |Vibrations of the pendulum. Treisnsoker, . . . . #5 Occultations of the fixed stars. Laplace, . . . . . . . # |Precession and nutation. # Theory of the moon. equator to the length of a degree on the parallel of the given latitude. From these principles is the following Table com- puted, for expressing the length of a degree of longitude in different latitudes, supposing the earth to possess a perfect sphericity. - - - Rºll ºf ººl Pºlº! Pººl ºf lºſſº 0 69-07 || 20 64-84 || 40 52-85 || 60 34°50 || 80 11-98 1 69-06 || 21 64,42 || 41 || 52-07 || 61 33:45 || 81 [10-79 2 | 60.03 || 22 || 63.97 || 42 51-27 || 62 || 32-40 || 82 || 9°59 | 3 | 68.97 || 23 63.51 || 43 50.46 || 63 || 31:33 || 83 8:41 | 4 || 6S-90 || 24 63.03 || 44 || 49-63 || 64 || 30-24 || 84 || 7-21 5 | 68.81 || 25 | 62-53 || 45 || 48-74 || 65 29:15 || 85 | 6-09 6 68.62 || 26 62-02 || 46 || 47-93 || 66 28-06 || 86 4-81 7 | 68.48 || 27 61.48 || 47 47.06 || 67 || 26-96 || 87 3-61 8 | 68-31 || 28 60.93 || 48 46. I6 || 68 || 25.85 || 88 || 2:41 9 | 68.15 || 29 || 60-35 || 49 || 45.20 || 69 || 24*73 || 89 || 1:21 10 | 67-95 || 30 59.75 || 50 44-35 || 70 23.60 || 90 || 0-00 || 11 || 67-73 || 31 59-13 || 51 43-42 || 71 22'47 || — — 12 67-48 || 32 || 58-51 || 52 || 43-48 || 72 21:32 tº e º - 13 | 67.21 || 33 57.87 || 53 41.53 || 73 20:17 | . . . . . . . 14 | 66.95 || 34 57.20 || 54 | 40-56 || 74 19:02 || . . . . . . . 15 | 66-65 || 35 | 56.51 || 55 49.58 || 75 || 1786 || . . . . . . . . 16 | 66-31 || 36 || 55.81 || 56 || 3S-5S || 76 1670 • * I e º e a. 17 | 65.98 || 37 || 55.10 || 57 87-58 || 77 15:52 e ſº tº e º º 18 65-62 || 38. 54-37 || 58 || 36-57 || 78 || 14-85 e e I e º s 2 19 || 65.24 || 39 53-62 || 59 || 35-54 || 79 || 13-17 • DeG Ree, in Universities, denotes a quality conferred on the students or members thereof, as a testimony of their proficiency in the arts or sciences, and entitling them to certain privileges. The degrees are much the same in all universities, but the laws thereof, and the previous discipline or exercise differ. The degrees are, Bachelor, Master, and Doctor; instead of H which last, in some foreign universities, they have Licentiate. DEINCLINERS, in Dialing, are those dials which both decline and incline or recline at the same time. - - DEISTS, in the modern sense of the word, persons in Chris- tian countries, who, acknowledging all the obligations and duties of natural religion, disbelieve revealed religion. They are so called from their belief in God alone. - - DELEGATES, Court of, is so called because the judges thereof are delegated by the king’s commission under the great seal, to hear and determine appeals in the three following cases: 1. Where a sentence is given in any ecclesiastical cause by the archbishop, or his official. 2. When any sentence is given in any ecclesiastical cause in the places exempt. 3. When a sentence is given in the admiral's court, in suits civil and marine, by order of the civil law. This commission is usually filled with lords spiritual and temporal, judges of the courts at Westminster, and doctors of the civil law. DELFT WARE, a kind of pottery covered with an enamel or white glazing, which gives it the appearance and neatness of porcelain. Some kinds of this enamelled pottery differ much from others, either in their sustaining sudden heat without breaking, or in the beauty and regularity of their forms, of their enamel, and of the painting with which they are ornamented. In general, the fine and beautiful enamelled ware, which ap- proaches the nearest to porcelain in external appearance, is at the same time that which least resists a brisk fire. Again, those which sustain a sudden heat are coarse, and resemble common pottery. This kind of ware has its name from Delft, in Holland, where it is made in large quantities. § DELIQUESCENCE, in Chemistry, denotes the property possessed by certain bodies, of attracting moisture from the air, and thereby becoming liquid. , • - - DELIQUIUM, in Chemistry, the dissolution or melting of a salt or calx by suspending it in a damp place under ground. DEMESNE, signifies the king's lands, appertaining to him in property. No common person has any domains, simply. understood, for we have no land (that of the crown only ex- cepted) which is not holden of a superior, as all depends either mediately or immediately on the crown. - - - DEMETRIUS, a celebrated Cynic philosopher, who lived in the time of the Emperor Vespasian. - .D E N ID E N 219 DICTIONARY of MECHANICAL SCIENCE. , , DEMI-CULVERIN, a piece of ordnance, the least of which is four one-fourth inches bore, 19 feet long, and 2000 lbs. weight. It carries a ball of four inches diameter, and of nine pounds weight, and its level range is 174 paces. A demi-culverin of the largest sort is four three-fourths inches bore, 10 one-third feet long, and weighs 3000 pounds. It carries a ball of four and a half inches diameter, weighing 12 pounds 11 ounces, point-blank 178 paces. - - DEMI-LUNE, Half Moon, in Fortification, an outwork con- sisting of two faces and two flanks. DEMISE, in Law, is applied to an estate in fee simple, fee tail, or for term of life, and so it is commonly taken in many writs. DEMQCRACY, in Law and polity, denotes a popular \ tº e government, or that where the supreme power is in the hands of the people. Such for a time were ancient Rome and Athens. DEMOCRITUS, one of the greatest philosophers of anti- quity, who flourished about 360 years before the Christian aera. DEMOIVRE, ABRAHAM, an eminent mathematician, was born in France, May 1667, but settled in England at the age of eighteen, where he continued to reside till his death, which happened in November 1754, in the eighty-first year of his age. DEMONSTRATION, a certain or convincing proof of some proposition. DeMonstration, in Logic, a series of syllogisms, all the premises of which are definitions, self-evident truths, or propo- sitions already established. - - DEMURRAGE, an allowance given to the commander of a trading ship by the merchants, for having detained him longer in port than the time previously appointed for his departure. DEMURRER, a pause or stop put to the proceedings of an action upon a point of difficulty, which must be determined by the court before any farther proceedings can be had therein. e that demurs in law confesses the facts to be true, as stated by the opposite party; but denies that by the law arising upon those facts any injury is done to the plaintiff, or that the defend-" ant has made out a lawful excuse. DEN ARIUS, in Roman antiquity, the chief silver coin among the Romans, worth in our money about 7#d. As a weight, it was the seventh part of a Roman ounce. DENDRITES, or ARBORIZATIONs, an appellation given to figures of vegetables observed in fossil substances, and which are of two kinds, the one superficial, the other internal. The first are chiefly found on the surface of stones, and between the strata and the fissures of those of a calcareous nature. They are mostly brown, changing gradually to reddish yellow. The internal dendrites are of a deep black. The most esteemed sorts are those found in agates, and particularly in the sar- donyx, cornelian, and other precious stones brought from the east, and which are commonly denominated Moka stones. . DENDROMETER, an instrument invented by Messrs. Dun- combe and Whittel, for which they obtained a patent, and so called from its use in measuring trees. It consists of a semi- circle divided into two quadrants, and graduated from the middle ; and upon the diameter there hangs a plummet for fixing the instrument in a vertical position. The principal use of it is for measuring the length and diameter of any tree per- pendicular or oblique to an horizontal plane, or in any situa- tion of the place on which it rests, or of any figure, whether regular or irregular, and also the length and diameter of the boughs, by mere inspection; and the inventors of it have calcu- lated tables, annexed to their account of the instrument itself, by the help of which the quantity of timber in a tree is obtained without calculation, or the use of the sliding rule. The den- drometer, fitted to a theodolite, may be applied to measuring the heights and distances of objects, accessible or inaccessible, whether situated in planes parallel or oblique to the plane in which the instrument is placed. It may be also used for taking all angles, whether vertical, horizontal, or oblique, in any posi- tion of the planes in which they are formed. DENEB, an Arabic term signifying tail, and hence applied to the names of certain stars in the tails of some of the constel- lations, as Deneb Adige in the tail of the Swan. DENIZEN. A denizen is an alien born, who has obtained letters patent whereby he is constituted an English subject. A denizen is in a middle state between an alien and a natural born or naturalized subject, partaking of the nature of both. He may take lands by purchase, or derive a title by descent through his parents or any ancestor, though they be aliens DENOMINATOR of ‘A FRAction, is that number written below the line, expressing the number of parts into which the * - (& unit is supposed to be divided ; thus, in the factions##. 12 and b are the denominators. - - . . . . 3 DENSITY, strictly speaking, denotes vicinity or closeness of particles; but in mechanical science it is used as a term of comparison, expressing the proportion of the number of equal moleculae, or the quantity of matter in one body to the number of equal moleculae in the same bulk of another body; density, therefore, is directly as the quantity of matter, and inversely as the magnitude of the body. Since it may be shewn experi- rimentally, that the quantities of matter, or the masses in different bodies, are proportional to their weight, of conse - quence, the density of any body is directly as its weight, and inversely as its magnitude ; or the inverse ratio of the magiii- tudes of two bodies, having experimentally equal weight (in the same place,) constitutes the ratio of their densities. No body is absolutely or perfectly full of matter, so as to have no vacuity or interstices; on the contrary, it is the opinion of Newton, that even the densest bodies, as gold, &c. contain but a small portion of matter, and a great portion of vacuity, or that they contain a great deal more pores or empty space than real substance. See IMPENETRABILITY. DENs 1TY of the Earth. The determination of the density of the earth, as compared with that of water, or any other known body, is a subject which has excited considerable interest amongst modern mathematicians, and nothing can at first sight seem more beyond the reach of human science, than the due solution of this problem, yet this has been determined, and on such principles, that if it be not correctly true, it is probably an extremely near approximation. The first idea of determin- ing the density of the earth was suggested by M. Bouguer, in consequence of the attraction of Chimboraco, which affected his plumb-line while engaged with Condamine in measuring a degree of the meridian, near Quito, in Peru. This led to the experiments on the mountain Schehallien, in Scotland, which were carried on under the direction of Dr. Maskelyne, and afterwards submitted to calculation by Dr. Hutton, who deter. mined the density of the earth to be to that of water, as 43 to 1. But in consequence of the specific gravity of the mountain being assumed rather less than it ought to have been, the above result is less than the true density, as has since been shewn by Dr. Hutton and Professor Playfair, the former of whom makes it, in his corrected paper, as 99 to 20, or nearly as 5 to 3. The same problem has been attempted on similar principles, but totally in a different manner, by the late Mr. Cavendish, who found the density of the earth to be to that of water, as 5:48 to 1. Taking a mean of all these, we have the density of the earth to that of water, as 5'24 to 1, and which, as we before observed, is probably an extremely near approximation. DeNSITY of the Planets. We have seen, in the preceding part of this article, that the density of a body is directly as its mass, and reciprocally as its magnitude; therefore, any two of these being given, the third may be undetermined. Now the magnitude of the several planets, as also of the sun, being sup- posed known from observation, if we can determine their masses, their densities will thus also become known. The power of attraction with which any central body acts upon another body revolving about it, is directly as the mass of the central body, and reciprocally as the square of the dis- tance of the revolving body; and this power may be measured by the deflection of the revolving body in a given time from the direction of its tangent. Now, if we consider the earth as the central, and the moon as the revolving body, the deflection of the latter in one second is known to be # of a foot, that is, it deviates so much from the direction of its tangent in one second of time, as may be readily ascertained by computation. being equal to the versed sine of the arc described in one second. If the distance between the earth and moon had been double what it is, this deflection would have been only 3 of the above, if the distance were only half what it is, this deflection 220 D E P D E S DICTIONARY OF MECHANICAI, Sg|ENCE. would be four times as much, and so on, because the power of the central body is reciprocally as the square of its distance. Again, if the distance of the bodies remain the same, and the mass of the central body be doubled, the deflection will be doubled; if tripled, the deflection will be tripled, and so on; because the power of the central body is directly as its mass. Now Jupiter's first satellite revolves about that planet at the same distance as the moon does about the earth, but its deflec- tion in one second is 256 times that of the moon; whence, the distances being equal, it follows, that the mass of Jupiter is 256 times greater than that of the earth. Had these distances not been equal, we must have found what the deflection of the moon would be at the given distance; then comparing this with that of the satellite, the mass in any other case might be determined. Having thus found the mass, and the magnitude being known, we shall have, assuming the mass of the earth as unity; as 1 divided by the magnitude of the earth, is to the mass of any planet divided by its magnitude ; so is 1, the density of the earth, to the density of the planet; and in this way the density of any planet having a satellite, may be readily computed. In other cases, recourse must be had to the dis- turbing force, which is of a very laborious computation. The density of the sun, and the several planets, as deduced from Laplace’s “System du Monde,” is as follows: viz. Sun, ............ 0-25226 Mars, ............ 0-65630 Mercury, ........ 2'58330 Jupiter, .......... 0-20093 Venus,........... 102400 | Saturn, .......... ... 0-10349 Earth, . . . . . . . . . . 1'00000 | Uranus, . . . . . . . . . . 0°21085 DENTIFRICE, a remedy for the teeth, of which there are various kinds; generally, however, they are made of earthy substances mixed with alum. Those formed of acids are very permicious. - DEODAND, in Law, is a forfeiture of that thing or animal which occasions the death of a human being by mischance. Where the death is purely accidental, and no blame attached . i. person, the coroner's jury usually find a deodand of one Snilling. - DEPARTURE, in Navigation, is the easting or westing of a ship in respect of the meridian it departed or sailed from: or it is the difference of longitude in miles either east or west, between the present meridian the ship is under, and that where the last reckoning or observation was made. * DEPOT, any place in which military stores are deposited. Also a particular place at the tail of the trenches, out of the reach of the cannon, where the troops generally assemble who are ordered to attack the outworks.’ - DEPRESSION OF EQUATIONs, in Algebra, is the reduction of an equation to one of lower dimensions, an operation, how- ever, that can only be effected in particular cases, viz. when a certain relation has place between the roots of the equation ; thus if an equation has equal roots with either like or contrary signs, or if the equation be a reciprocal one, having each pair of roots the reciprocal of each other, and in short under almost any known relation of the roots the equation may be depressed to one of lower dimensions. If an equation have two equal roots, it may be depressed one degree; if three equal roots, it may be depressed two degrees, and so on; and in reciprocal equations of even dimensions, may be depressed to half the original degree; and if they are of odd dimensions, to half the original degree minus 1. - DEPRESSION of the Pole. When za person sails or travels towards the equator he is said to depress the pole : be- cause as many degrees as he approaches nearer the equator, so many degrees will the pole be nearer the horizon. This arises from the spherical figure of the earth. When a star is under the horizon it is termed the depression of that star under the horizon. The altitude or depression of a star is an arch of the vertical circle, or azimuth, intercepted between the horizon and the star. . s DEPRE8510N, or Dip of the Visible Horizon, denotes its sink- ing ºr dipping below the true horizontal plane, by the observer's eye being raised above the surface of the sea; in consequence of which the observed altitude of an object is by so much too great. The following table shews the dépression or dip at the horizon of the sea for different heights of the eye. TABLE, Height of Dip of the Height of Dip of the Height of Dip of the | the eye. horizon. ..] the eye. horizon. the eye. hörizon. Feet. J iſ Feet, ' " || Feet. / // 1 || 0 57 13 3 26 26 4 52 2 1 21 14 3 34 28 5 3 3 I 39 15 3 42 30 5 14 4 l 55 16 3 49 35 5. 39 5 ... 2 8 17 3 56 40 6 2 6 2 20 || 18 h 4 3 || 45 6 24 7 2 31 19 4 10 5() 6 44 8 2 42 20 4 16 60 7 23 9 2 52 21 4 22 70 7 59 10 3 1 22 4 28 80 8 32 11 3 10 23 4 34 90 9 3 12 3 J.8 24 4 40 100 9 33 DERHAM, John, an eminent philosopher and mathemati- cian, born at Worcester in 1657, was the author of many valuable articles in the “Philosophical Transactions,” &c. Derham died in 1738, at º - - DERWIS, a name given to all Mohammedan monks, though of various orders. They have convents in the same manner as the monks in the Catholic and Greek churches. DESAGULIERS, JoHN THEo. an eminent experimental philosopher, was born at Rochelle, in France, in 1683, but educated in England, where he afterwards continued to reside. He was a member of several learned societies, and made numerous communications on the subjects of optics, mechanics, &c. both to the Royal Society of London, and to the Academy of Sciences at Paris. DESCENSION, RIGHT, the arc of the equator which descends with the sign or star below the horizon of a direct sphere; and oblique Descension is the arc of the equator that descends with the sun or star in an oblique sphere. DESCENT of Bodies, in Mechanics, is their motion or tendency towards the centre of the earth, either in a direct or oblique direction. The laws of the descent of bodies in free space are given in the article AcceleRAtion, their descent along inclined planes in the article INCLINEI, PLANE, and in fluids under Resist ANCE. We shall, there- fore, merely refer to a singular phenomenon respecting falling bodies, which is their deviation from the perpendicular, occa- sioned by the rotation of the earth on its axis. When the idea of the earth’s motion was started by Copernicus, it was strongly objected to it, that if the earth really revolved, a stone let fall from the top of a tower ought to fall considerably to the westward of the foot of it, being, according to their notion, left behind by the motion of the earth; and the supporters of the doctrine were not then sufficiently acquainted with the compo- sition of motion to explain away the difficulty. However, when the laws of motion became better understood, it was discovered, that the body, instead of falling to the westward of the tower, ought to fall a little to the eastward oi it, in consequence of the velocity of rotation being greater at the top than at the foot of the tower; and this deviation is said to have been realiy detected by M. Guglielmini and M. Benzenberg, the former finding it to be equal to 8 lines in falling 241 feet, and the latter 5 lines for a fall of 262 feet. But how far experiments on such delicate subjects may be depended on, may be a mat- ter of doubt, but of the truth of the theoretical deflection no doubt can be entertained. DESCENT, in Heraldry, expresses the coming down of any thing from above; as, a lion en descent with his head towards the base points and his heels towards one of the corners of the chief, as if he were leaping down from some high place. Descent, Line of Swiftest, is that which a body, falling by the action of gravity, describes, in the shortest time possible, from one given point to another. And this line is the arc of a ºil, when the one point is not perpendicularly over the Other. - DESCENT, in Law, is the title by which a man, on the death of his ancestor, acquires his estate by right of representation D E V D E V 221 DICTIONARY OF MECHANICAL SCIENCE. as his heir at law; and an estate so descending to the heir is in law called the inheritance. - - DESIDERATUM, the desirable accomplishment of some advancement in art or science; as, the use of pendulums where there are irregular motions. DESIGN, in Painting, the first idea of a large work drawn roughly, and on a small scale, with the intention of being executed and finished in large. See DRAWING. In Music, design means both the invention and execution of the subject, in all its parts, and agreeably to the general order of the whole. In Manufactures, design expresses the figures with which the workman enriches his stuff or silk, and which he copies after his own drawing or the sketches of some artist. In Building, the term ichnography may be used, when by design is only meant the plan of a building, or a flat figure drawn on paper; when some side or face of the building is raised from the ground, we may use the term orthography: and when both front and sides are seen in perspective, it may be termed Scenography. . DESCRIBENT, in Geometry, is the line or surface, from the motion of which, a surface, or body, is supposed to be generated or described. - DESCRIPTIVE GeoMETRY, the name given to a species of geometry almost entirely new, and which we owe in great mea- sure to M. Monge. When any surface whatever penetrates another, there most frequently result from their intersection curves of double curvature, the determination of which is necessary in many arts, as in groined vault-work, cutting arch-stones, wood-cutting, for ornamental work, &c. the form of which is frequently very singular and complicated ; it is in the solution of problems appertaining to these subjects that descriptive geometry is especially useful. DETACHED Pieces, in Fortification, are outworks at a distance from the body of the place; as demilunes, ravelines, bastions, &c. In Painting, the figures are well detached, when they stand free and disengaged from each other. DETACHMENT, in Military affairs, a number of soldiers drawn out from regiments or companies equally, to be em- ployed as the general thinks proper; whether on an attack, at a siege, or in parties to scour the country. I) ETERMINATE PROBLEM, in Geometry, that which has a limited number of answers: as the following, viz. To describe an isoceles triangle on a given line, whose angles at the base shall be double that at the vertex. DETINUE, in Law, a writ which lies where any man comes to goods or chattels either by delivery or by finding, and re- fuses to give them up; and it lies for the detaining, when the detaining was unlawful. DETONATION, in Chemistry, the noise and explosion which any substance makes upon the application of fire. It is also called fulmination. Hence the detonating balls, detonat- ing powder. DEVELOPMENT, a term in frequent use among modern algebraists, to denote the transformation of any fraction into the form of a series. DEVELOPMENT OF A SPHERIC SURFACE on A PLANE, is applied to the drawing of a small portion of the earth's surface in a manner nearly spherical, by supposing the sphere circum- scribed by a polyhedron, the side of which is extended upon a plane. In approximating the development of the spheric Sur- face, there are two methods of considering the subject : one, by supposing the polyhedrous surface to consist of conic frus- tums, each touching the surface of the sphere in the middle ; the other, by supposing the polyhedrous surface comprised of frustums of a cylinder, meeting each other in planes passing through the centre of the sphere, and intersecting each other in one common diameter as an axis; and because both the conic and cylindric surfaces are developable, the surface of the circumscribing polyhedron will also be developable, and there- fore will admit of being correctly represented. Now, suppos- ing all the sides of the figure to be equal, and increased in number at pleasure, the greater the number, the nearer will the surface of the polyhedron coincide with that of the sphere; and consequently, any portion of the developed surface of the polyhedron, will be very nearly equal and similar to the corresponding portion of the spheric surface. Each of these different methods of representing the spheric surface has its peculiar advantage and disadvantage, when applied to the art of map-making : the comic method of development is best adapted to represent countries to any extent in the differ- ence of longitude, or round the whole circumference of the earth if required, to a certain extent in difference of latitude : and the cylindric method of development is well adapted to represent countries contained between any two parallels of latitude, but not to have any considerable difference of longi- tude. Of these two different projections by development, the conical projection is the most simple, and is attended with the least trouble, on account of the facility of describing the parallels of latitude in concentric circles, and the meridians in straight lines. In comparing a spherical zone to a truncated cone, in order to construct its development, we view the parallels as circles described from the summit of the come taken as a common centre; and the meridians are right lines subjected to pass through that point. It is visible that the result will approach the nearer, in proportion as the map shall embrace less extent in latitude. This projection may vary in different ways; for it may be supposed that the cone is a tan- gent to the middle parallel of the map, and in consequence, exterior; or, that it may be in part inscribed in the sphere, that is to say, formed by the secants of the meridians. . In the first case, the map will not be perfectly exact, except on the middle parallel, which will preserve in its development the length which it really possesses on the sphere; but the paral- lels placed above and beneath, will exceed those on the sphere, which are correspondent. With respect to the application of the development of the comic surface in the construction of maps, the Rev. Patrick Murdoch proposed to substitute to the tangent cone, a cone partly inscribed and determined upon this condition, that the part of the area comprehended in the map, should be equivalent to that of the spherical zone which it represents.” Though it may be difficult, at first sight, to conceive that the surface of the globe can be represented by a part of the surface of a cone, yet this is the case in regard to D'Anville's map of Russia. You may easily form the surface of a cone, of any plain piece of paper cut into a circular form or base ; and you will as easily consider, that if a cone about twice the height of the semi-diameter of the globe, were to be conceived as standing on the same base with the hemisphere, namely, on the equator, the surface of such a come would in part lie within the surface of the globe; and then, nothing can be more natural, than to Suppose that the surface of the globe at so small, a distance from the surface of the cone, might be very easily projected or delineated on it; and in such a case, the projection of the countries and their bearings, distances, &c. will be very nearly the same on the surface of the included part of the cone, as on that of the globe itself; and when such a geographical conical surface is cut out and expanded, it makes the map now under consideration. - When any portion of the earth’s surface is projected on a plane, or transferred to it by whatever method of description, the real dimensions, and often the figure and position of coun- tries, are much altered and misrepresented. The particular methods of description used among geographers are so various, that we might suspect them to be faulty; but in most of their works we find these two blemishes, the linear dimensions visibly false, and the intersections of the circles oblique; so that a quadrilateral space shall often be represented by an oblique-angled rhomboid figure, whose diagonals are very far from equal ; and yet, by a strange contradiction, you shall see a scale of distances inserted in such a map. The last of these blemishes is removed, and the other lessened, in some maps of P. Schenk's of Amsterdam, a “map of the Russian empire,” the “Germania Critica” of the famous Professor Meyer, and a few more. In these the meridians are straight lines, converg- ing to a point, from which, as a centre, the parallels of latitude are described, and I have given a rule for drawing such maps, under the article MAPs. * See the Editor's Treatise on the Construction of Maps, for this deve- lopment, p. 113, &c. 3 L 222 D 1 A D I A DictionARY of MECHANICAL science. DEVISE, or Device, in Heraldry, Painting, and Sculpture, any emblem used to represent a certain family, person, action, or quality, with a suitable motto applied in a figurative sense. Devise, in Law, the act whereby a person bequeaths his lands or tenements to another, by his last will and testament. The person who makes this act, is called the devisor, and he in whose favour the act is made, is termed the devisee. DEW, that condensation of vapour which we perceive on the grass of the fields, &c. and which is produced by the evapo- ration of moisture from the earth, both before and after sun- set. Under certain circumstances, the air holds not the same quantity of water in solution, and the result is a deposition of it in aqueous particles; during day, and under the effects of electricity, definite and floating clouds are the result, and the processes of rain often commence; but in fine weather, in the evening, the vapour plane being destroyed, the vapour so deposited precipitates down in dew. During the heat of the day a great quantity of vapour is thrown into the atmosphere from the surface of the earth and waters. When the evening returns, if the vapour has not been carried off in part by cur- rents, it will often happen that more remains diffused in the general atmosphere than the temperature of the night will permit to subsist under the full pressure of the aqueous atmo- sphere. A decomposition of the latter then commences, and is continued until the general temperature and aqueous pressure arrive at an equilibrium, or until the returning sun puts an end to the process. Dew appears only on calm and clear nights: very little is ever deposited in opposite circumstances, and little only when the clouds are very high. It is never seen on nights both cloudy and windy; and if in the course of the night the weather, from being serene, should become dark and stormy, dew which had been deposited will disappear. In calm weather, if the sky be partially'covered with clouds, more dew will appear than if it were entirely uncovered. DIABETES, in Physic, an excessive discharge of urine, which comes away crude, and exceeds the quantity of liquids drank. § DIACAUSTIC CURWE, a species of the caustic curves formed by refraction. - DIACOUSTICS, or DI APHoNics, the consideration of the properties of sound refracted in passing through different mediums. DIAERESIS, in Grammar, the division of one syllable into two, which is usually noted by two points over a letter, as aulaï instead of aulae, dissoliienda for dissolvenda. DIAGNOSTIC, in Medicine, a term given to those signs which indicate the present state of a disease, its nature and Cà U.S.C. . DIAGONAL, in Geometry, a right line drawn across a quadrilateral or other figure, whether plane or solid, from the vertex or summit of one angle to that of another; and is by some authors called the diameter, and by others the diametral of the figure. It is demonstrable, 1. That every diagonal divides a parallèlogram into two equal parts. 2. That two diagonals drawn in any parallelogram bisect each other. 3. A line passing through the middle point of the diagonal of a parallelogram, divides the figure into two equal parts. 4. The diagonal of a square is incommensurable with one of its sides. 5. The sum of the squares of the two diagonals of every paral- lelogram is equal to the sum of the squares of the four sides. 6. In any trapezium, the sum of the squares of the four sides is equal to the sum of the squares of the two diagonals, together with four times the square of the distance between the middle points of the diagonals. 7. In any trapezium, the sum of the squares of the two diagonals is double the sum of the squares of two lines bisecting the two pairs of opposite sides. 8. In any quadrila- teral inscribed in a circle, the rectangle of the two diagonals is equal to the sum of the two rectangles under the two pairs of opposite sides. 9. In every parallelopiped the sum of the squares of the four diagonals of the solid, is equal to the sum of the squares of its twelve edges. 10. In every hexaedron, regular or not, the sum of the squares of the twelve edges, plus the sum of the squares of the twelve diagonals of the faces, is equal to three times the sum of the squares of the four diago- mals which cross the solid, plus four times the sum of the squares of the six right lines which join, two by two, the mid- dle points of those four latter diagonals. 11. In every poly- gon, and in every polyédron, the sum of the squares of the lines which join, two by two, the middle points both of sides and diagonals, is the quarter of the sum of the squares of those sides and diagonals; multiplied by the number of summits of the polygon or polyédron, diminished by two units. 12. A farther generalization of the latter property leads to the most celebrated property of the centre of gravity. DIAGRAM, is a scheme for explanation or demonstration of any figure, or of its properties. DIAL, or SUN-DIAL, an instrument serving to measure time, by means of the shadow of the sun. The word is formed from dies, day, because indicating the hour of the day. The ancients also call it sciathericum, from its doing it by the shadow. DIAL is more accurately defined, a draught, or description, of certain lines on a plane, or surface of a body given, so con- trived as that the shadow of a stile, or ray of the sum, passed through a hole therein, shall touch certain points at certain hours. The antiquity of dials is beyond doubt. Some attri- bute their invention to Anaximenes Milesius, and others to Thales. Vitruvius mentions one made by the ancient Chaldee historian Berosus, on a reclining plane, almost parallel to the equinoctial. Aristarchus Samius invented the hemispherical dial. And there were some spherical ones, with a needle for a gnomon. The discus of Aristarchus was an horizontal dial, with its limb raised up all round, to prevent the shadows stretching too far. It was late ere the Romans became acquainted with dials. The first was set up by Papirius Cur- sor, at or near the temple of Quirinus; but being inaccurate about 30 years after, another was brought out of Sicily by the consul M. Valerius Messala, which he placed on a pillar near the Rostrum ; but neither did this shew time truly, because not made for that latitude; and after using it 99 years, Martius Philippus set up another more exact. - The diversity of sun-dials arises from the different situation of the planes, and from the different figure of the surfaces upon which they are described; whence they become denominated. equinoctial, horizontal, vertical, polar, direct, erect, declining, inclining, reclining, &c. Universal DIAL. There are several kinds of dials called universal, because they serve for all latitudes. One of a very ingenious construction has lately been invented by Mr. G. Wright, of London. arch C, Universal Dial. MA The hour circle, or arch E, and latitude are the portions of two meridian circles; one fixed, and the other moveable. The hour or dial-plate S E I at the top, is fixed to the arch C, and has an index that moves with the hour circle E.; therefore the construction of this dial is perfectly similar to the con- Struction of the meridians and hour- circles upon a common globe. The peculiar problems to be performed by this instrument are, 1. To ſind the latitude of any place. 2. ‘The latitude of the place being known, F to find the time by the sun and stars. 3. To find the sun or stars altitude H and azimuth. But the dial being properly ad- B justed, a great variety of astrono- mical and trigonometrical problems may be wrought upon it, which, Fº however, our limits will not allow of Iºr detailing; we must therefore refer the reader to Jones’s “Instrumental Dialing,” where he will find ample information on this subject. DIALING, the art of drawing dials on the surface of any given body, whether plane, or curved. Dialing is wholly founded on the first motion of the heavenly bodies, and chiefly the sum ; or rather on the diurnal motion of the earth; so that the elements of spherics, and spherical trigonometry, should be understood before a person advances to the theory of dialing. The edge of the plane by which the time of the day is found, is called the stile of the dial, which must be parallel to the earth’s axis; and the line on which this plane is erected, is called the W º sº tº º §º W. iſſiſſiſirºu tº -- |Wilt! frºm D I A D I A 223 DICTIONARY OF MECHANICAL SCIENCE. substile. The angle included between the substile and stile, is called the elevation or height of the stile, as in the next figure. The principles of dialing may be aptly illustrated by the phenomena of a hollow or transparent sphere, as of glass. Thus suppose a PB p to repre- sent the earth as transparent; and its equator as divided into 24 equal parts by so many meridian semicircles a, b, c, d, e, &c. one of which is the geo- graphical meridian of any given place, as London, which it is supposed is at the point a ; and if the hour of 12 were marked at the equator, both upon that meridian and the opposite one, and all the rest of the hours in order on the other meridians, those meridians would be the hour circles of London; because, as the sun appears to move round the earth, which is in the centre 6f the visible heavens, in 24 hours, he will pass from one meridian to another in an hour. Then, if the sphere had an opaque axis, as PE p, terminating in the poles P and p, the shadow of the axis, which is in the same plane with the sun, and with each meridian, would fall upon every particular meridian and hour, when the sun came to the plane of the opposite meridian, and would consequently shew the time at London, and at all other places on the same meridian. If this sphere were cut through the middle by a solid plane A B C D in the rational horizon of London, one half of the axis EP would be above the plane, and the other half below it; and if straight lines were drawn from the centre of the plane to those points where its circum ference is cut by the hour circles of the sphere, those lines would be the hour lines of an horizontal dial for London; for the shadow of the axis would fall upon each particular hour line of the dial, when it fell upon the like hour circle of the sphere, as in the annexed figure. If the plane which cuts the sphere be upright, as A F C G, touching the given place, for example, London at F, and di- rectly facing the meridian of London, it will then become the plane of an erect direct south dial; and if right lines be drawn from its centre E, to those points of its circumference where the hour circles of the sphere cut it, these will be the hour lines of a vertical or direct south dial for London, to which the hours are to be set in the figure, contrary - to those on an horizontal dial; and the lower half Ep of the axis will cast a shadow on the hour of the day in this dial, at the same time that it would fall upon the like hour circle of the sphere, if the dial plane was not in the way. If the plane still facing the meridian, be made to incline or recline, any number of degrees, the hour circles of the sphere will still cut the edge of the plane in those points to which the hour lines must be drawn straight from the centre; and the axis of the sphere will cast a shadow on these lines at the respective hour. The like will still hold, if the plane be made to decline by any number of degrees from the meridian towards the east or west, provided the declination be less than 90 degrees, or the reclination be less than the co-latitude of the place, and the axis of the sphere will be the gnomon; other- wise, the axis will have no elevation above the plane of the dial, and cannot be a gnomon. Thus it appears that the plane of every dial represents the ... s. plane of some great circle on the earth, and the gnomon of the earth's axis; the vertex of a right gnomon, the centre of the earth or visible heavens; and the plane of the dial is just as far from this centre as from the vertex of this stile. The earth itself, compared with its distance from the sun, is considered as a point; and, therefore, if asſāall sphere of glass be placed upon any part of the earth's surface, so that its axis be parallel to the axis of the earth, and the sphere have such lines upon it, and such planes within it, as above described; it will shew the hours of the day as truly as if it were placed at the earth's centre, and the shell of the earth were as transparent as glass. To describe an Horizontal Dial, geometrically, as in the an- nexed figure. — Draw a meridian line KL, (see MeRIDIAN • Line,) and from any part C, erect the perpendicular CD, and make the angle C A D = to the latitude of the place, and draw the line d'E, meeting within E. Make EB = C D, and from the centre B, with radius E B, describe a quadrant E B F, which divide into six equal parts. Through E draw Eh per- pendicular to A. B. From the centre B through the several subdivisions of the quadrant E F, draw the lines B a, B b, &c. meeting the line d ?. - in the points a, b, c, &c. From E draw the line E h, and set off E e, Ff, Eg, &c. respective equal to Ea, E b, E c, &c. Through the point A draw the lines a XI, b X, c IX, &c. also e I, f LI, g III, &c. which will be the several hour lines required. Then at A erect the gnomon or stile at an angle equal to the elevation of the pole, or latitude of the place, and the dial will be complete. To compute the Angles of the Hour Lines, trigonometrically. As Radius . Is to the sine of the latitude of the place, So is tangent of sun’s distance from the meridian, _To the tangent of the angle from the meridian on the dial. *The preceding construction and computation for the case of a horizontal dial, may be said to include the whole theory of dialing; for there is no plane, however obliquely situated with respect to any given place, but what is parallel to the horizon of some other place, and therefore, if we find that other place by a problem on the terrestrial globe, or by a trigonometrical calculation, and construct a horizontal dial for it, that dial applied to the plane where it is to serve, will be a true dial for that place.—Thus, an erect direct south dial in 5139 north lati- tude, would be a horizontal dial on the same meridian, 90° Southward, which falls in with 3849 south latitude; but if the upright plane declines from facing the south at the given place, it would be a horizontal plane 90° from that place; but for a different longitude, which would alter the reckoning of the hours accordingly. - A TABLE of the Angles which the Hour-Lines form with the Meridian on a Horizontal Dial for every half Degree of Latitude, from 50° to 59° 30'. - . * A. M., | A. M. A. M. l A. M. A. M. A. M. LATITUDE. I. XI. I. I. I. X. III. IX. IV.VIII'v. VII. VI. VI. O f o o o o o , o , 50 11 38|23 51 ||37 - 27 53 0170 4390 0 50 30 ll 41 |24 || 37 40|53 1 I 70 51 |90 () 51 ! l 46|24 10 ||37 51 |53 24|70 58.90 () 5l 30 11 51 |24 H9|38 453 36|| 7 || 6 || 9() {} 52 l 1 55 24 27; 38 I 453 46||71 1390 () 52 30 12 0|24 36||38 23|53 5871 2090 G 53 12 5|24 45 38 37|54 8| 71 27 90 0 53 30 12 9|24 54|38 48||54 1971 34|90 () 54 12 14|25 238 58|54 2971 4090 0 | 54 30 12 18|25 10|39 8||54 39|71 47|90 0 || 55 12 23|25 19| 39 i9||54 49|71 53|90 0 || 55 30 12 28||25 27|39 29|54 59.71 5990 0 } 56 12 32|25 35|39 40|55 8|72 590 0 56 30 12 36||25 45 39 50}55 18|72 1290. 0. 57 12 40 ||25 51 39 59|55 27|72 1790 * 0. 57 30 12 44|25 58|40 9|55 3772 22 90 O 58 12 48|26 540 1855 4572; 2790 0 58 30 12 52|26 13|40 27|55 54|72 3390 0 59 12 56 26 20 |40 36|56 2|72 39|90 0 59 30 13 0 |26 27 | 40 45|56 10|72 4490 0 J * | 224 D I A D I A DICTIONARY OF MECHANICAL SCIENCE. : In this table, the angles formed by the lines for V in the morning and VII in the evening, IV in the morning and VIII in the evening, &c. are not marked, because they are the same as those for VII in the morning and V in the evening, VIII in the morning and IV in the evening, only they lie on oppo- site sides of the VI o’clock hour-lines, as was shewn in the construction of the horizontal dial. . The use of the table may be easily comprehenced: if the place for which a horizontal dial is to be made, corresponds with any latitude in the table, the angles which the hour-lines make with the meridian may be seen at once. For example, it appears that the hour lines of XI and I must, in the latitude of 569, make angles of 12° 32' with the meridian. If the lati- tude be not contained in the table, proportional parts may be taken without any sensible error. Thus, if the latitude be 54° 15', and the angles made by the hour-lines of XI or I be required, as it appears from the table that the increase of 30 in the latitude, viz. from 54° to 54° 30', corresponds to an increase of 4 in the hour angle at the centre of the dial, we may infer, that an increase of 15' will require an increase of 2. nearly, and therefore that the angle required will be 12° 16'. DIALING-GLOBE, an instrument of brass or wood, with a plane fitted to the horizon, and an index so contrived as to give a clear illustration of the scientific principles on which dials are constructed. . DIALING-LINES, or ScALEs, are graduated lines placed on rulers, or the edges of quadrants and other instruments, for the construction of dials. These are, 1. A scale of six hours, which is a double tangent, or two lines of tangents, each of 45°, set together in the middle, and equal to the line of sines, with the declination set against the meridian altitudes in the lati- tude of the place. 2. A line of latitudes, fitted to the hour- scale, and made by this canon: As the radius; the chord of 90° : : the tangents of each respective degree of the line of Iatitudes : tangents of other arcs. And then the natural sides of these arches are the numbers, which taken from a diagonal scale of equal parts, shall graduate the divisions of the line of latitudes to any radius. The lines of hours and latitudes are general, for pricking down all dials with centres. The other scales are particular, and give the several requisites for upright declining dials by inspection. They are, 1. A line of chords. 2. A line for the substile's distance from the meridian. 3. A line for the stile's height. 4. A line of the angle of 12 and 6. 5. A line of inclination of meridians. DIALING-SPHERE, an instrument made of brass, with several semicircles sliding over each other on a moveable horizon, to demonstrate the nature of spherical triangles, and to give the true idea of drawing dials. DIAMETER, in Geometry, the line which, passing through the centre of a circle, or other curvilinear figure, divides it, or its respective ordinates, into equal parts. Conjugate DIAMETER of a Conic Section, is a line drawn through the centre of the figure to its sides, and the shortest of the two diameters of the figure. Transverse DIAMETER of a Conic Section, is a line drawn through the foci to the curve. How to find the DIAMETER of Shot or Shells.-For an iron ball, whose diameter is given, supposing a mine-pounder, which is nearly four inches, say the cube root 2:08, (of nine pounds,) is to four inches, as the cube root of the given weight, is to the diameter sought. Or, if 4 be divided by 2:08, the cube root of 9, the quotient 1923 will be the diameter of one-pound shot, which being continually multiplied by the cube root of the given weight, gives the diameter required. Or by logarithms thus: If the logarithm of 1923, which is 2.83979, be constantly added to the third part of the logarithm of the weight, the sum will be that of the diameter. Suppose a shot to weigh 24 lbs. add the given logarithm (283979 to 460070, the third part of the logarithm I-3802112 of 24, the sum 7440494 will be the loga- rithm of the diameter of a shot weighing 24 pounds, which is 5'5468 inches. If the weight should be expressed by a frac- tion, the rule is the same ; for instance, the diameter of a pound and a half ball, or three seconds, is found by adding the logarithm 2839793 found above, to 0586971, one-third of the logarithm of two-thirds; the sum '3426764 will be the logarithm of the diameter required; i.e. 2:2013 inches. 2 º' . .* . . . Carats. DIAMETER of the Planets, &c. in Astronomy, are either real or apparent. The real diameters are the absolute measure of them in miles, &c. and their apparent diameters are the angles under which they appear to spectators on the earth, and are therefore different under different circumstances ; viz. accord- ing as they are nearer or more remote from the earth. As these angles are very small, the diameter of the planet may be con- sidered as part of a circle of which the earth is the centre, and they are said to contain so many minutes, seconds, &c. as is measured by that arc, and consequently, the apparent diameter of a planet is in the inverse ratio of its distance. And hence again, the apparent diameters and distances being known their real diameters thence become determined. . TABLE of the Mean and Apparent Diameters of the Planets. Apparent mem Apparent Mean Apparent diameter, as diameter, as diameter fin diameter of seen from the seen from 2nglis the sun, Proportional earth. the sun, miles. se: ºthe diameter. planets. - Sun . . . . 32' 2" | . . . . . . 882269 . . . . . . 110'000 Mercury, 11".8 16" 3.124. 80' - "4 Venus . . . 57"-9 30" 7702 46' - •9 Earth . . . . . . . . . . . 17". 4 7916 32" . 1-0 Mars... . 8".94 10" 4398 || 21' ' ' ' '5 Jupiter.. 397 37/ 91522 6'. I I 1-6 Saturn. . 18" 16" 76068 3'-4 9°8 Uranus . 3'-54 4" 35] 12 1'.6 4:25 Moon , ... 31' 26".5 4"-6 2160 | 32! 27 y *, DIAMOND, see CHEMISTRY, for the properties of the dia- mond. There are various kinds of diamonds, as the Cornish, Rose Arran, &c. but these are inferior to the diamonds of Brazil; and these last to the gems of India. Diamond, in the glass trade, is an instrument used for cutting glass, in which is set, in lead or silver, a crystal or gem that will cut glass. DIAMOND, in Heraldry, expresses the black colour in the achievements of peerage. . DIAMond Mines are found in Brazil, in South America; and in Golconda, Visapour, Bengal, and the island of Borneo. The diamond can only be cut and ground by itself and its own sub- stance. To bring it to that perfection which augments its price so considerably, they begin by rubbing several against each other while rough, after having first glued them to the ends of two wooden blocks, thick enough to be held in the hand. It is this powder thus rubbed off the stones, and received in a little box for the purpose, that serves to grind and polish the stones. Diamonds are cut and polished by a mill, which turns a wheel of soft iron sprinkled over with diamond dust mixed with oil of olives. The same dust, well ground and diluted with water and vinegar, is used in the sawing of diamonds, which is performed with an iron or brass wire, as fine as a hair. Some- times, in lieu of sawing the diamonds, they clean them, espe- cially if there are any large shivers in them. • = . The first water, in diamonds, means the greatest purity and perfection of their complexion, which ought to be that of the purest water. When diamonds fall short of this perfection, they are said to be of the second or third water, &c. till the stone may be properly called a coloured one ; for it would be an impropriety to speak of an imperfectly-coloured diamond, or one that has other defects, as a stone of a bad water only. For the valuation of diamonds of all weights, the following rule has been given. First, suppose the value of a rough diamond to be settled at £2 per carat at a medium, then to find the value of diamonds of greater weights, multiply the square of their weight by 2, and the product is the value required: e.g. To find the value of a rough diamond of two carats; 2 × 2 = 4, the square of the weight, which multiplied by 2, gives £8, the true value of a rough diamond of two For finding the value of manufactured diamonds, we suppose half their weight to be lost in manufacturing them ; and therefore, to find their value, we must multiply the square of double their weight by 2, which will give their true value in pounds. Thus, to find the value of a wrought diamond weigh- ing two carats; we first find the square of double the weight, D I F. D I G. 225 DICTIONARY OF MECHANICAL SCIENCE. viz. 4 x 4 = 16; then 16 × 2 = 3-2. So that the true value of a wrought diamond of two carats is £32. On these princi- ples Jeffries has constructed tables of the price of diamonds from 1 to 100 carats. The value of diamonds, however, depends so much on imagination, and not on real use, that no positive rule can be given. In the very large diamonds, Jeffries’s rule will be far from the truth.-Diamond chemically analyzed, is found to consist of puré carbon, that is, charcoal. DíAMond, Brilliant, is that which is cut in faces at the top and bottom; and whose table, or principal face at top, is flat. D1AMond, Rose, is one that is quite flat underneath, with its upper part cut in many little faces, usually triangles, the upper- most of which terminates in a point. DIANAE ARBOR, or ARB or LUNAE, in Chemistry, the beau- tiful crystallizations of silver, dissolved in nitrous acid, to which some quicksilver is added; and so called from their re- sembling the trunk, branches, leaves, &c. of a tree.—CSee page 53, col. 2.) . . . - * - DIANTHUS, a genus of plants belonging to the class diandria, or hermaphrodite plants, as the clove gilliflower, carnation, pink, sweet-william, &c. - - DIAPASON, in Music, an interval that expresses the octave of the Greeks, or a rule or scale whereby musical instrument makers adjust the pipes of organs, and cut the holes of haut- boys, flutes, &c. in due proportion, for performing the tones, semitones, and concords, with precision. - - DIAPHRAGM, in Anatomy, the midriff, a strong muscular substance that separates the breast and thorax from the abdo- men, and thus portions off the abdominal and thoracic viscera. DIARRHCEA, or LooseNess, in Medicine, is a frequent and copious evacuation of liquid excrement by stool. DIARY, a journal or day-book, containing an account of every day’s proceedings. - DIASTOLE, in Physic, signifies the dilatation of the heart, auricles, and arteries; and stands opposed to the systole, or contraction of the same parts. - - DIATESSARON, in Music, applied by the Greeks to that interval which we call a fourth; consisting of a greater tone, a lesser tone, and one greater semitone. The word is also used for the four gospels, arranged after the manner of a harmony. DIBBLING, in Agriculture, a mode of setting corn, or other seeds, practised with advantage in places where labour is cheap; it is chiefly used for putting wheat crops into the ground. The practice of dibbling was first introduced into Norfolk, about twenty-five years ago. The method of dibbling is this : when the land is ploughed and rolled, a man with an iron dibble, of about three feet long, in each hand, walking backwards, makes two rows of holes in each furrow, at about four inches' distance from each other, and an inch or two deep. The dibbler is followed by two or three women, or children, who drop two or three grains into each hole. The field is after- wards bush-harrowed. The usual quantity of seed, is from a bushel and a half to two bushels per acre, and the expense of labour about ten shillings. An experienced dibbler, with three active attendants, will plant half an acre a day, making six holes in every foot length. - DICE, among gamesters, certain cubical pieces of bone or ivory, marked with dots on each of their faces, from one to six, according to the number of faces. Sharpers have several ways of falsifying dice: 1. By sticking a hog's bristle in them so as to make them run high or low as they please. 2. By drilling and loading them with quicksilver; which cheat is found out by holding them gently by two diagonal corners; for if false the heavy sides will turn down. 3. By filing and rounding them. But all these ways fall short of the art of the dice makers; some of whom are so dexterous, that sharping game- sters will give any money for their assistance. - DIET, in Medicine, comprehends the whole regimen or ruel of iife, with regard to the six non-naturals ; air, meats and drinks, sleep and watching, motion and rest, passions of the mind, retentions and excretions. Or it may merely imply eating and drinking, or solid aliments and liquids. DIETETICS, the Science or Philosophy of Diets: that which teaches us to adapt particular foods to particular organs of digestion, or to particular states of the same organs; so that the greatest possible portion of nutriment may be extracted Papin about the beginning of the last century. from a given quantity of nutritive matter; or a sufficient por- tion may be obtained with the least possible quantity of organic action and exhaustion. ... • DIFFERENCE, is the remainder, after taking the less of two quantities from the greater. . . Difference of Longitude of two places, is an arc of the equator contained between the meridians of those places. DIFFERENTIAL, in the higher Geometry, is an infinitely small quantity, or part of quantity, so small as to be less than any assignable one, and is thus denominated, because it is frequently considered as the difference of two quantities, and as such is the foundation of the diſferential calculus. DifferentiAL Calculus, is a method of differencing quanti- ties, or of finding an infinitely small quantity, which being taken infinite times shall be equal to a given quantity; or it is the arithmetic of the infinitely small differences of variable quanti- ties; and thus differs in its metaphysics from the fluxional calculus, those quantities which in the former are considered as infinitely small differences, being in the latter supposed to be the infinitely small or momentary increments of variable or flowing quantities. - - t DIGESTER. The digester is an instrument invented by Mr. It is a strong vessel of copper or iron, with a cover adapted to screw on with pieces of felt or paper interposed. A valve with a small aper- ture is made in the cover, the stopper of which valve may be more or less loaded, either by actual weights, or by pressure from an apparatus on the principle of the steelyard. The pur- pose of this vessel is to prevent the loss of heat by evaporation. The solvent power of water when heated in this vessel is greatly increased. Papin's digester was constructed on the principle of mechanical pressure being necessary to elevate fluids to higher temperatures than their common boiling points. . . - A is the boiler; B the lid, fastened down by four screws; C a valve to allow the escape of a small portion of steam, to prevent the bursting of the apparatus; D is a notched lever, on which a weight E hangs, to prevent the valve from rising by a slight expansion of the steam. The weight is heavy according to the strength and thickness of the iron of which the digester is formed. The whole apparatus is generally made very strong, to prevent accidents. Animal bones are dissolved with great facility in these digesters, in order that the gelatine confined in them may be converted into rich soups, &c. For this purpose, they have been much used in hotels, coffee-houses, and family establishments. The heat of the water contained in this apparatus, is so intense as to melt lead. - I)IGESTION, in Medicine, is the dissolution of the aliments into such minute parts as are fit to enter the lacteal vessels and circulate with the mass of blood. The food is first conveyed to the stomach, where by means of the gastric juice it is con- verted into chyme. The chyme passes into the intestinal canal, where it is subjected to a new process, being gradually decom- posed and converted into chyle and excrementitious matter, which by means of the bile are separated from each other. The excrementitious matter is evacuated, but the chyle is absorbed by the lacteals, and conveyed to the blood vessels by the lungs. DIGGING, among miners, the operation of freeing ore from the stratum in which it lies, where every stroke of their tools turns to account: in contradistinction to the openings made in search of such ore, which are called hatches or essay-hatches, and the operation itself, tracing of mines, or hatching. DIGITS, or MonADEs, in Arithmetic, signify any integer under 10, as 1, 2, 3, 4, 5, 6, 7, 8, 9. * - - - DIGGLES, Leo NARD, an English mathematician, born at Barham, in Kent, and educated at University college, Oxford, wrote a treatise on “Surveying,” “Geometry,” and “Prog- nostication everlasting of right good Effect,” or, “ Choice Rules to judge the Weather by Sun, Moon, and Stars,” &c. He died about 1574. - • * • . - - D1GG Les, Thomas, son of the preceding, educated at Oxford, after which he became muster-master-general of the forces sent º 2 M 226 D I P DJ I. O In ICTIONARY OF MECHANICAL #CEENCE. by queen Elizabeth to the Netherlands. He wrote some mili- tary pieces, and some on astronomy, and other subjects of mathematics. He died in 1595. . . . . - DIGIT, in Arithmetic, signifies any one of the ten numerals, 1, 2, 3, 4, 5, 6, 7, 8, 9,0. The word comes from digitus, a finger; thus indicating the humble means originally employed in com- putations. DIGIT, is also a measure equal to three-fourths of an inch. • - : • Digit, in Astronomy, is the measure by which we estimate the quantity of an eclipse. The diameter of the sun or moon's disc is conceived to be divided into 12 equal parts, called digits; and according to the number of those parts or digits which are obscured, so many digits are said to be eclipsed. When the luminary is wholly covered, the digits eclipsed are precisely 12; and when it is more than covered, as is frequently the case in lunar eclipses, then more than 12 digits are said to be eclipsed. DIKE, or DYKE, a ditch or drain; and also a work of stone, timber, or fascines, raised to oppose the passage of the waters of the sea, a lake, river, or the like. DILAPIDATION, is where an incumbent of a church living suffers the parsonage-house or out-houses to fall down, or be in decay for want of necessary reparations; or it is the pulling down or destroying any of the houses or buildings belonging to a spiritual living, or destroying of the woods, trees, &c., ap- pertaining to the same ; for it is said to extend to committing or suffering any wilful waste, in or upon the inheritance of the church. - DIMENSION, in Geometry, is either length, breadth, or thickness. Thus a line has only one dimension, length ; a sur- face two, length and breadth ; and a body or solid, length, breadth, and thickness. DIMENsion of an Equation, or any other quantity in Algebra, is used with regard to the highest power that enters into its composition; thus an equation is said to be of one, two, three, &c. dimensions, according as it involves the simple quantity, the square, cube, &c.; so that a simple equation is of one dimension, a quadratic of two, a cubic of three, &c. DIMINUTION, in Architecture, a contraction of the upper part of a column, by which its diameter is made less than that of the lower part. DIMINUTion, in Law, where the plaintiff or defendant in a writ of error, alleges, on an appeal to a superior court, that part of the record is omitted, and remains in the inferior court not certified; whereon he prays that it may be certified by certiorari. - * DIMINUtion, in Music, when there are several words, which are to make tones, and several quick motions in a cadence, several quavers, semiquavers, &c., corresponding to a crotchet or minim, as when a semibreve is divided into two minims, four crotchets, &c. - DIMINUTIVE, in Grammar, a word formed from some other, to diminish the force of it, or to signify a thing is little in its kind. Thus Hal is a diminutive of Henry. DINOCRATES, a celebrated Macedonian architect, who flourished in the time of Alexander. DIOCESE, the circuit of every bishop's jurisdiction. For this realm hath two sorts of divisions; one into shires or coun- ties, in respect to the temporal state; and another into pro- vinces, in regard to the ecclesiastical state, which provinces are divided into dioceses. The provinces are two, Canterbury and York; whereof Canterbury includes twenty-one dioceses, or sees of suffragan bishops; and York three, besides the bishopric of the Isle of Man, which was annexed to the pro- vince of York by king Henry the Eighth. - DIONAEA MUSCEPULA, or Venus's Fly-Trap, in Botany, a sensitive plant, in the construction of which nature seems to have had some view towards its nourishment, in forming the upper joint of its leaf like a machine to catch food; and placing upon the middle of it the bait for the insect that becomes its prey. The plant is of the monogynia order, in the decandria class. It grows in America, in wet shady places, and flowers in July and August; the glands of those exposed to the sun are of a beautiful red colour, but those in the shade are of a pale green. are perennial. The leaves are numerous, and placed in a cir- The roots are squamous, sending forth few fibres, and cular order, jointed and succulent; the upper joints consist of two lobes, of a semi-oval form, with the margins furnished with stiff hairs, which lock in each other when they close; the upper surfaces of these lobes are covered with red glands, each of which appears, when highly magnified, like a compressed arbutus berry. The stalk is about six inches high, round, smooth, and without leaves, ending in a spike of flowers, milk- white, and standing on footstalks, at the bottom of which is a little painted bractea or flower-leaf. - DIONYSIUS, an ancient geographer, supposed to have flourished in the time of the first Augustus Caesar. - DIOPHANTINE ANALYsis, or Problems, in Algebra, are certain questions relating to square, cube, &c. numbers, and rational right-angled triangles; the properties of which were first discussed by Diophantus, in his “Arithmetic.” DIOPTRICS, or ANAcLAstics, the doctrine of refracted vision, which investigates and explains the effects of light refracted by passing through different mediums, as air, water, glass, &c. and particularly lenses. See REFRACTION and LeNs. DIP of the Horizon, is an allowance made in all astrono- mical observations of altitude for the height of the eye above the level of the sea. - DIPHTHONG, in Grammar, a double vowel, or the mixture of two vowels pronounced together so as to make one syllable. DIPLOMATICS, a word derived from diploma, in this instance signifying the king’s letters patent, for the immediate expediting of an ambassador or envoy to a foreign court. The art of diplomatics has been cultivated with great assiduity by every nation in Europe for very many years past, and, men experienced in political history, of engaging manners, and possessing a considerable share of duplicity, have always been selected by each to practise it. . DIPPING, among Miners, signifies the interruption of a vein of ore; an accident that gives them a great deal of trouble before they can discover the ore again. - DIPPING NEEDLE, or INCLINATory Needle, a magneti- cal needle, so hung, as that, instead of playing horizontally, and pointing north and south, one end dips or inclines to the hori- zon, and the other points to a certain height above it, as shewn in the following results of several of the most accurate experiments that have yet been made on this subject. LATITUDES | LONGITUDES DIP of the NORTH | DATES of North. East. ENID of the NEEDLE. Observation. 53° 55t 1939 39' 699 10' 1778 49 36 233 10 72 29 - West. . . . 52 24 83 30. 79 17 1775 44 5 8 10 71 34 1776 38 53 12 1 70 30 34 57 14 8 66 12 29 18 16 7 62. 17 - 24 24 18 11 59 () } 20 47 19 36 56%, 15 15 8 23 38 51 () | 12 1 23 35 48 26 10 0 22 52 44 12 5 2 20 10 37 25 South. O 3 27 38 30 3 4 40 30 34 22 15 7 3 33 21 17 57 * , 11 25 34 24 9 15 } East. South and below. - 16 45 208 12 29, 28 19 28 204 11 41 0 21 8 185 0 39 1 1777 35 55 18 20 45 37 1774 41 5 174 13 63 49. 1777 45 47 || 166 18 70 5 1773 The inventor of this instrument was one Robert Norman, a compass maker, of Wapping, about the year 1576. . . Some have endeavoured to find the latitude and longitude of D I S D I S DHCTIONARY | OF MECHANICAL SCIENCE. 227 places by means of the dipping needle, particularly Burrowes, Gilbert, Bond, Whiston, &c.; but as nothing of importance followed fronrtheir attempts, it would be useless to enter upon any explanation of their particular methods in this place. But the following general rule may be adopted:—In order to find the longitude or latitude by the dipping needle. If the lines of equal dip, below the horizon, be drawn on maps, or sea charts, from good observations it will be easy, from the longitude known, to find the latitude; and from the latitude known, to find the longitude. Suppose, for example, you were travelling or sailing along the meridian of London, and found the angle of dip, with a needle of one foot, to be 75°, the chart will shew, that this meridian and the line of dip meet in the latitude of 53° 11'; which therefore is the latitude sought. Or suppose you were travelling or sailing along the parallel of London, i.e. in 51° 32' north latitude, and you find the angle of dip to be 74°. This parallel, and the line of this dip will meet in the map in 1946 of east longitude from London, which is therefore the longitude sought. - DIRECT, a term frequently used in Arithmetic, Astronomy, Optics, &c. to denote some peculiar condition or circumstance, as Direct Proportion, Ratio, Rays, Vision, &c. for which see the respective substances. DIRECT, in Astronomy. See ConsequentiA. DIRECT Dial, is one which points directly to any one of the four cardinal points, and is hence called direct east, west, north, or south dial, according to the point towards which it is directed. DIRECT Sphere. See RIGHT Sphere. . DIRECTION, in Astronomy, the motion and other pheno- mena of a planet when direct. Line of DIRECTion, in Gunnery, is the direct line in which the piece is pointed; and, in Mechanics, the same term implies the line in which a body moves, or in which a force is applied. When two conspiring forces act on a body at the same time, the angle included between the lines of their direction is called the angle of direction. Number of DI Rection, in the Calendar, is the number of days that Septuagesima Sunday falls after the seventeenth day of January. Quantity of DIRECTION, in Mechanics, is a term sometimes used to denote what is more commonly called Momentum. DIRECTLY, is used in nearly the same sense as direct; thus we say, quantities are directly proportional, which is only another way of stating them to be in direct proportion; and in Mechanics, one body is said to impinge directly upon another, when the former strikes the latter perpendicular to its surface. DIRECTRIX, in the Conic Sections, is a certain right line perpendicular to the axis of the curve, and frequently referred to in treating of the properties of those figures, from the description of them in plano. - DIRECTRIX, or Dirigent, is also that line or plane alon which another line or plane is supposed to move, in the gene. ration of a surface or solid. DISABLED, the state of a ship when, by the loss of her masts, sails, yards, or rigging, by springing a leak, receiving Some fracture in the hull, or other disaster, she is rendered incapable of prosecuting her voyage without great difficulty and danger. DISC, the face of the sun or moon, as either luminary appears to the naked eye. + Disc, in Optics, is the width of the aperture of telescope glasses, whether plane, convex, concave, &c. DISCHARGE of FLUIDs, through apertures in the sides and bottoms of vessels, is a subject which has engaged the attention both of theorists and experimentalists; and may be considered under either point of view. We shall first state the principal propositions in the theoretical part of the subject, and then give some of the most remarkable and accurate experiments, by Bossut, Venturi, Eytelwein, Vince, Young, Leslie, &c. - 1. If a fluid runs through a pipe or tube of an uniform shape, equal quantities of it will pass through every parallel section of the tube. This is evident, because the same quantity of fluid must pass through the same section in the same time. But though the water runs with the same velocity through G — every section of the tube, it does not run with equal velocity through every part of the same section. Its motion is swiftest towards the middle, and slower towards the sides of the tube, where it is retarded by friction. - . . 2. If a fluid runs through a tube or pipe, kept constantly full by means of a proper supply, but which is not of uniform shape; then the velocity of the fluids, in different sections, will be inversely as the areas of the sections. For since the tube is always full, the same quantity of water must pass through every section of it in the same time; but if the area of one section be half as great as the area of another section, the same quantity of water cannot pass through both sections at the same time, unless it pass through the former section with double the velocity with which it passes through the latter. If the area of the former section be one-third, or one fifth, of the area of the latter, the same quantity of water must pass through the former with a velocity which is three times, or five times, the velocity with which it passes through the latter. Hence the velocities must be inversely as the areas of the sections. 3. If a fluid, flowing through a small orifice in the bottom of a vessel, be kept constantly full by an uniform supply at the top, the velocity of the discharging fluid will be equal to that acquired by a heavy body in falling freely through the height of the surface of the fluid above the orifice. —---— Let M N OP represent a vessel filled N Sº ° with a non-elastic fluid up to the level of - * I K; M. P, the bottom in which is the I K. is aperture C D (very small in comparison with MP), C I KD the column of the fluid standing directly above the aperture, and C A B D the lowest lamina of the fluid immediately contiguous to the aper- ture. Also let v denote the velocity which a heavy body would acquire in falling Al– B freely through B D, the height of the &T; lamina; and V the velocity acquired by the same lamina during its descent through the same space until it is discharged by the pressure of the column CIK D. If we suppose the lowest lamina of fluid A C D B, to fall as a heavy body through the height B D, its moving orifice will be its own weight. Again, suppose it to be accelerated by its own weight, together with the pres- sure of the ambient fluid, about the column CIKD; viz. by the weight of the column CIK D through the same space; that is, while it is accelerated from quiescence until it is actually discharged: then the velocity in the former case will be to that in the latter, as the moving forces and the times in which they act directly, and the quantities of matter moved inversely. But the moving forces are to each other, as the heights B D and KD; the times in which they act are inversely as the velocities, the space through which the body is accele- rated being given; and the quantities of matter moved are B.D . K D. ——y- KD, or v : V :: M BID: V B D. Now v is the velocity which a heavy body would actually acquire in falling through the space B D ; consequently V, the velocity of the discharging fluid, is that which a heavy body would acquire in falling through KI), the whole altitude of the fluid above the orifice. Ng Tºo G. II. M P equal; therefore v : V : : whence v2 : V2 : : B D : 4. In the same manner it may be shown that if a pipe be inserted horizontally in the vessel M N OP the plate of fluid A C-B will be discharged with the same velocity as before (if its centre of pres- sure be of the same depth), whatever be the thickness of the plate; this velocity c not depending upon a continual accele- † j, ration through the length of the tube, . - E. otherwise the effluent fluid could not attain its full velocity, until a column had been discharged whose base is equal to the orifice, and height equal to the length of the tube; whereas we find by experience, that this full velocity can be attained by the thinnest plate which can be let escape from the aperture. 228 HD' I S D I s DICTIONARY OF MECHANICAL SCIENCE. 5. The velocities and quantities discharged at different depths, are as the square roots of the depths. 6. The quantity run out in any time is equal to a cylinder, or prism, whose base is the area of the orifice, and its alti- tudes the space described in that time by the velocity acquired by falling through the height of the fluid. So that if h denote the height of the fluid, a the area of the aperture, g = 323 ºth feet, or 386 inches, and t the time of efflux, we shall have, for the quantity discharged, Q = a t V 2 g h,-or, - - When a and h are expressed in feet, Q = 8-0208 at V h feet. When a and h are expressed in inches, Q = 27-7387 at V h I Il Cºl. w - . If the orifice is a circle whose diameter is d, then 0-785398 dº must be substituted for a ; - And when d and h are expressed in feet, Q = 6.29952 d V h feet. - When d and h are expressed in inches, Q = 2178592 d 12 AV h inches. - And from either of these it will be easy to find either a, t, or h, when the other three quantities are given. - 7. The force with which the effluent water impinges against any quiescent body, is proportional to the altitude of the fluid above the orifice. For the force is as the velocity multiplied by the quantity of matter; but the quantity discharged, in a given time, is as the velocity; therefore the force is as the square of the velocity; that is, by the demonstration of the proposition, (art. 3.) as the height of the fluid. 8. The water spouts out with the same velocity whether it be downwards, or upwards, or sideways; because the pressure of fluids is the same, in all directions, at the same depth. 9. When a vessel is left to discharge itself gradually, through an orifice in its bottom, if the area of the section parallel to the bottom be every where the same, the velocity of the surface of the fluid, and consequently the velocity of the efflux, will be uniformly retarded. For (by prop. 2.) the velocity of the descending surface is to the velocity at the surface, as the area of the orifice to the area of the surface, which is a constant ratio; consequently, the velocity of the descending surface varies as the velocity at the orifice, or as the square root of h; that is, the velocity of the descending surface varies, as the square root of the space which it has to describe: so that this exactly corresponds with the case of a body projected perpen- dicularly upwards, where the velocity is as the square root of the space to be described: whence, as the retarding force is constant in the instance referred to, it must also be constant in the case before us, and the retardation uniform. From this comparison we deduce the following obvious corollaries. The quantities of water in a prismatic vessel, discharged through an aperture in the bottom, decrease in equal times; as the series of odd numbers 1, 3, 5, 7, 9, &c. taken in an inverted order. The quantity of water contained in an upright prismatic vessel, is half that which would be discharged in the time of the entire gradual evacuation of the vessel, if the water be kept always at the same altitude. . . . . - . . • . . . 10. If upon the altitude of the fluid in a vessel, as a diame- ter, we describe a semi-circle, the horizontal space described by the fluid spouting from a vertical orifice, at any point in the diameter, will be as the ordinate of the circle drawn from that point; the horizontal space being measured on the plane of the bottom of the vessel. When the aperture is vertical, and indefinitely small (as supposed here), the fluid will spout out horizontally with the velocity due to the altitude of the fluid above the orifice (by prop. 3); and this velocity, combined with the perpendicular velocity arising from the action of gravity, will cause every particle, and consequently the whole jet, to describe the curve of a parabola. Now the velocity with which the fluid is expelled from any A B hole, as G, is such as if uni- formly preserved would carry a particle through a space equal to 2 B G, in the time of the fall through B G ; but, after quitting the orifice, it describes the para- bolic curve, and arrives at the horizontal plane C F in the same time as a body would fall freely 5– v GD: 2BG: DE= - through G. D.; so that to find the distance D E, since the times - are as the roots of the spaces, we have this analogy v G B: 2 B G. A/G D — - *}#}= avºc.go=agh, by the nature of the circle. And the same will hold with respect to any other point in B D. If the apertures be made at equal distances from the top and bottom of the vessel (kept full of fluid), the horizontal distances to which the water will spout from these apertures will be equal. For when D g = B G, we shall have 2 V B g. g D = 2 MB G. G. D, and consequently D E the same in both cases. When the orifice is at the point bisecting the altitude of the fluid in the vessel, the fluid will spout to the greatest distance on the horizontal plane; and that distance, if measured on the plane of the bottom of the vessel, will be equal to the depth of the fluid in it. For I K, the ordinate from the centre I, is the greatest which can be drawn in the semi-circle, and D F, which is ~ 2 IK, is then = 2 B I - B D. ... We have already extended this article, and therefore mus be very brief in stating the results of the principal experiments that illustrate, this interesting inquiry. With respect to the quantity of fluid discharged, Bossut's experiments, made with peculiar accuracy, demand particular notice. They are ex- pressed in the following table, which exhibits the quantity of fluid discharged through orifices pierced in thin plates; in measures of the Paris foot royal, which is to the English foot, aS 1066 to 1000. . . - - - - Constant Altitude of . Theoretical Discharges | Real Discharges in the the Water in the Re- || in one Minute through Time through the servoir above the a circular Aperture of same Orifice, expres- Aperture, in Paris Tin, expressed in Cu- Sed also in , Cubic Feet. bic Inches. Inches. , 1 4381 2722 2 6196 3846 3 7589 4710 4 8763 5436 5 9797 6075 6 10732 6654 7 I 1592 º 7183 | 8 12392 - 7672 9 13144 8135 10 13855 8574 11 14530 8990 12 15180 9384 13 15797 9764 14 16393 101.30 15 16968 10472 The following is another set of experiments made by the same author with different apertures; in which the water was kept constantly at the altitude of eleven feet, eight inches, ten lines, from the centre of each aperture. Cubic Inches furnished in Experiments. - - me Minute. 1. Horizontal circular aperture, 6 lines diameter, .. 2311 2. Circular horizontal aperture, 1 inch diameter,. . 9281 3. Circular horizontal aperture, 2 inch diameter,. . 37203 4. Rectangular horizontal aperture, 1 in. 3 lines, .. 2933 5. Square horizontal aperture, 1 inch, ... . . . . . . . . 11817 6. Square horizontal aperture, 2 inches,.......... 4736]. . . Constant height of water 9 feet. 7. Lateral circular aperture, 6 lines diameter, .... 2018 8. Lateral circular aperture, 1 inch diameter, .... 8135 Constant height of water 4 feet. - 9. Lateral circular aperture, 6 lines diameter, .... 1353 10. Lateral circular aperture, 1 inch diameter, ... , 5436 Constant height of water 7 lines. 11. Lateral and circular orifice, 1 inch diameter, .. 628 From these experiments we may derive the following deduc- tions; viz. - * ..., 1. The quantities of fluid discharged, in equal times, from different sized apertures, the altitude of the fluids being the same, are to each other nearly as the areas of the apertures. D H S D I S DICTIONARY OF MECHANICAL SCIENCE. 229 2. The quantities of water discharged, in equal times, by the same aperture, with different altitudes of water in the reser- voir, are nearly as the square roots of the corresponding alti- tudes of the water in the reservoir above the centre of the aperture. - - - - ... " 3. That, in general, the quantities of water discharged, in the same time, by different apertures, and under unequal alti- tudes of the water in the reservoir, are to each other in a com- pound ratio of the areas of the apertures, and the square roots of the altitudes. - 4. That on account of the friction, the smallest apertures dis- charge proportionally less water than those that are larger and of a similar figure, the water in the respective reservoirs being at the same height. 5. That of several apertures whose areas are equal, that which has the smallest circumference will discharge more water than the other, the water in the reservoirs being at the same altitude, and this because there is less friction. Hence, circular apertures are most advantageous, as they have less rubbing surface under the same areas. To this we can only add, that if instead of the orifice being pierced in a plate of tin or other thin plate, a cylindrical pipe or tube be inserted in the vessel whose length is from two to four times the diameter of the orifice, then a greater quantity of water will be dis- charged through it than through the simple aperture, in an equal portion of time, all other circumstances remaining the same ; the quantity of the fluid discharged, in the two cases, being to each other as 133 to 100 nearly. . . DISCHARGED, when applied to a ship, signifies when she is unladen, or her stores, ammunition, &c. taken out. When expressed of the officers or crew, it implies when they are dis- banded from immediate service. When spoken of cannon, it means when it is fired off DISCHARGER, or DiscHARGING Rod, in Electricity, is a rod used for the purpose of discharging a jar or battery of its contents, without injury or pain to the operator. Different forms have been given to this instrument, which are described by Cavallo and other authors on electricity. DISCOUNT, or ReBATE, is an allowance made on a bill or any other debt not yet become due, in consideration of present payment. Bankers, merchants, &c. allow for discount a sum equal to the interest of the bill for the time before it becomes due, which however is not just ; for as the true value of the discount is equal to the difference between the debt and its present worth, it is equal only to the interest of that present worth, instead of the interest on the whole debt. And there- fore the rule for finding the true discount is this: As the amount of £1 for the given rate and time is to the given sum or debt, so is the interest of £1 for the given rate and time to the discount of the debt. Thus if the interest or discount of money were five per cent. then the allowance on a bill of £100 would be found thus: As 21s. : £100 : : 20s. : £4.15s. 23#d. Such, however, is not the way in which business is done ; for science has oſten as little to do with business as friendship. And the following is the popular rule, as given in all arithmetic books in vogue in our scientific schools. Thus Walkingham: As £100 present money will discharge a debt of £105 to be paid a year to come, rebate being made at 5 per cent.—Rule. As £100 with the interest for the time given, is to that interest, so is the sum given to the rebate required. Subtract the rebate from the given sum. and the remainder will be the pre- sent worth.—Example. What is the discount and present worth of £487. 12s. for six months, at 6 per cent, per annum ? e riº a £. .. 6. s. 6 m. Å) 6 As 103 : 3 : : 487 12 —- 20 20 3 100 2060 9752 * 3 103 - - - amºmºmºmº 2060)2925|6(14l. 4s. rebate. 206 - £. s. . . . . 487 12 865 14 4 .' ' 824 £473, 8 present worth. TTG-4s. me 25. DISCRETE, or Disjunct Proportion, is that in which the ratio between two or more pairs of numbers is the same, and yet the proportion is not continued, so as that the ratio may be the same between-the consequent of one pair and the ante- cedent of the next pair. Thus 3: 6:: 5: 10 is a disjunct pro- portion; but 3: 6:: 12: 24 is a continued proportion. DISCRETE Quantity, is such as is not continued and joined together. Such, for instance, is any number; for its parts, being distinct units, cannot be united into one continuum ; for in this there are no actual determinate parts, as there are in a number composed of several units. DISCUTIENTS, in Surgery, are external remedies, which dissolve or disperse a stagnated or coagulated fluid. * DISGORGE, in the Manege, is used for discussing or dispersing an inflammation or swelling : thus, if a horse’s legs j gorged or swelled, we say he must be walked out to disgorge €II). DISJUNCTIVE PROPOSITION, in Logic, is that where of several predicates we affirm one necessarily to belong to the subject, to the exclusion of all the rest, but leave that par- ticular one undetermined. DISLOCATION, the putting a bome out of joint by violence. DISMANTLED, the state of a ship unrigged, and all her stores, guns, &c. taken out in readiness for being laid up in ordinary, or for any other purpose. - DISMASTED, the state of a ship deprived of her masts, whether by design or accident. - DISMOUNTED, the state of a cannon taken off a carriage, or when, by the enemy's shot, the carriage is so broken as that the gun is rendered unmanageable. - - DISPARTING, in Gunnery, is setting a mark upon the muz- zle ring, or thereabouts, of a piece of ordnance, so that a sight taken upon the top of the base ring, against the touch-hole, by the mark set on or near the muzzle, may be parallel to the axis of the concave cylinder. DISPENSARY, a charitable institution, common in large towns of Britain. Dispensaries are supported by voluntary subscriptions, and each has one of more physicians, surgeons, and apothecaries, who attend, or ought to attend, at stated times, in order to prescribe for the poor, and, if necessary, to visit them at their own habitations. The poor are supplied with medicines gratis. Where these institutions are managed with care, they are of the utmost importance to society, it being unquestionably more for the comfort of the sick to be attended at their own houses, than to be taken from their families to an hospital. DISPERSION, commonly signifies the scattering or dissi- pating the parts of any body; and hence, in Optics, it denotes the same as divergency. Point of DisPersion, in Dioptrics, the point from which the refracted rays begin to diverge when their refraction renders them divergent. Dispersion of Light, in Optics, denotes the enlargement of a pencil or beam of light, which is produced by its passage from one medium to another; and this enlargement arises from the nature of the medium. JDISSEISIN, in Law, is the wrongful putting out of one seised of the freehold, which may be effected either in corpo- real inheritances or incorporeal. Disseisin of things corporeal, as of houses and lands, must be by entry and actual disposses— sion of the freehold. Disseisin of incorporeal hereditaments, cannot be an actual dispossession, for the subject is neither capable of actual bodily possession nor dispossession, but is only at the election and choice of the party injured, if, for the sake of more easily trying the right; he is pleased to suppose himself disseised. And so in corporeal hereditaments, a man may frequently suppose himself to be disseised, when he is not in fact, for the sake of entitling himself to the more easy remedy of an assise of novel disseisin, instead of the process of a writ of entry. DISSENTERS, in Church History, a numerous body of peo- | ple in this country, who made their first appearance in Queen |Blizabeth's time, when, on account of the extraordinary purity which they proposed in religious worship and conduct, they were reproached with the name of Puritans. They increased in numbers by the act of uniformity, which took place on Bartho- 3 N 230 D I S D I S DICTIONARY OF MECHANICAL SCIENCF. lomew's day 682, in the reign of Charles II. By this act, 2000 ministers of the establishment, refusing to conform to cer- tain conditions, were obliged to quit their livings, and hence arose the name of Non-conformists. The descendants of these are known by the name of Protestant Dissenters: and may be considered, in general, as divided into the denominations of Presbyterians, Independents, and Baptists. . DISSIPATION, in Physics, an insensible loss or consump- tion of the minute parts of a body, or that agency whereby they fly off and are lost. - Circle of DissipAtion, in Optics, denotes the circular space upon the retina, which is taken up by one of the extreme pencils of rays issuing from any object. e Radius of DissipAtion, is the radius of the circle of dissi- ation. DISSOLVENT, any thing which dissolves. DISSOLUTION, the separation of a body into its most minute parts. DISTANCE, in Astronomy, the space between the sum and any of the planets, &c. as shewn in the following table of the real and proportional distances of the several planets. Proportional Real Mean Dist. Mean Dist. Mercury, . . . . . . *3870.981 . . . . . . 36) Venus, . . . . . . . . ‘7233323 . . . . . . 68 Earth, ... . . . . . 1°0000000 . . . . . . 93 Mars, . . . . . . . . . 1°5236935 . . . . . . 142 Vesta, . . . . . . . . 2°2373000 . . . . . . 221 to º ºr tº • * Juno, . . . . . . . . . 2°6671630 . . . . . . . 248 ºilº Ceres, . . . . . . . 2,7674060 . . . . . . 257 o Pallas, ......... 27675920 . . . . . . 257 Jupiter, ....... 52027911 . . . . . . 485 Saturn ........ 9:5387705 . . . . . . 890 Uranus, . . . . . . 19:1833050 . . . . . . 1800 J DISTANCE of the Fixed Stars from the Earth or Sun, has never yet been determined; we only know it is so great, that the whole diameter of the earth’s orbit, which is near two hun- dred million miles, is but as a point compared with their dis- tance, and therefore forms no sensible measure whereby it may be estimated. . DistANce of the Sun from the Moon's Node or Apogee, is an arch of the ecliptic intercepted between the sun's true place and the moon’s mode or apogee. e Accessible DistANces, are such as may be measured by the application of any lineal measure. Inaccessible DISTANCEs, are those which cannot be measured by the application of any lineal measure, but by means of angles and trigonometrical rules and formulae. See ACCESSIBLE. The distance of objects may also be ascertained by means of sound; for as this has been found, by experiment, to travel at the rate of about 1142 feet per second, if the time which elapses between the firing of a gun and the report of the same be duly observed, the distance in feet will be found by multiplying the number of seconds by 1142; and in this way we may estimate the distance of a thunder cloud, by the number of seconds being observed that elapses between the flash of lightning, and the clap of thunder by which it is succeeded. See Acoustics. Apparent DistANCE, in Optics, is that distance at which we judge an object to be placed when seen afar off, and which is usually very different from the true distance, because we are apt to think that all very remote objects whose parts cannot well be distinguished, and which have no other object in view near them, are at the same distance from us, though perhaps one of them is thousands of miles nearer than the other, as is the case with the sun, moon, and planets. . The most universal, and frequently the most sure means of judging of the distance of objects, is the angle made by the optic axis. For our two eyes are like two different stations, by the assistance of which distances are taken; and this is the reason why those persons who are blind of one eye so fre- quently miss their mark in pouring liquor in a glass, snuffing a candle, and such other actions as require that the distance be exactly distinguished. To convince ourselves of the usefulness of this method of judging of the distance of objects, we have only to suspend a ring in a thread, so that its side may be towards us, and the hole in it to the right and left hand; and taking a small rod, crooked at the end, retire from the ring two or three paces, and having with one hand covered one of our eyes, to endeavour with the other to pass the crooked end of the rod through the ring. This appears very easy, and yet upon trial, perhaps once in 100 times we shall not succeed, especially if we move the rod a little quickly. By persons recollecting the time when they began to be subject to the mis- takes above mentioned, they may tell when it was that they lost the use of one of their eyes, which many persons are long igno- rant of, and which may be a circumstance of some consequence to a surgeon. The use of this second method of judging of distances, De Chales limits to 120 feet, beyond which, he says, we are not sensible of any difference in the angle of the optic axis. A third method of judging of the distance of objects consists in their apparent magnitudes. From this change in the mag- nitude of the image upon the retina, we easily judge of the distance of objects, as often as we are otherwise acquainted with the magnitude of the objects themselves; but as often as we are ignorant of the real magnitude of bodies, we can never, from their apparent magnitude, form any judgment of their distance. From this we may see why we are so frequently deceived in our estimates of distance, by any extraordinary magnitudes of objects seen at the end of it, as in travelling towards a large city, or a castle, or a cathedral church, or a mountain larger than ordinary, we fancy them to be nearer than we find them to be. This also is the reason why animals, and all small objects seen in valleys contiguous to large mountains, appear exceedingly small. For we think the mountain nearer to us than if it were smaller, and we should be surprised at the smallness of the neighbouring animals, if we thought them farther off. For the same reason we think them exceedingly small when they are placed on the top of a mountain, or a large building, which appears nearer to us than it really is, on account of its extraordinary size. Our imagining objects, when seen from a high building, to be smaller than they are, and smaller than we fancy them to be when we view them at the same distance on level ground, is because we have no distinct idea of distance in that direction, and therefore judge of the things by their pictures upon the eye only, but custom will enable us to judge rightly even in this case. Let a boy who has never been upon a high building, go to the top of the Monument, and look down into the street; the objects seen there, as men and horses, will appear so small as greatly to surprise him. But ten or twenty years after, if in the mean time he has used himself now and then to look down from that and other great heights, he will no longer find the same objects to appear so small. The finest sight of this. nature is from a balloon. See AERostATION. We have had a very fine sight ourselves of this nature, in surveying from the lofty spire of St. Denis, in France, a large army in the plain between that cathedral and Paris. And if a person were to view the same objects from such heights as frequently as he sees them upon the same level with himself in the streets, they would appear to him just of the same magnitude from the top of the Monument as they do from a window one story high. For this reason it is, that statues placed upon very high buildings ought to be made of a larger size than those which are seen at a nearer distance, because all persons, except architects, are apt to imagine the height of such buildings to be much less than it really is. The fourth method by which we judge of the distance of objects, is the force with which their colour strikes upon our eyes. For if we be assured that two objects are of a similar and like colour, and that one appears more bright and lively than the other, we judge that the brighter object is the nearer of the two. - The fifth method consists in the different appearance of the small parts of objects. When these parts appear distinct, we judge that the object is near; but when they appear con- fused, or when they do not appear at all, we judge that it is at a greater distance. For the image of any object, or part of an object, diminishes as its distance from our eye increases. The sixth and last method by which we judge of the distance D I S D I S DICTIONARY OF MECHANICAL SCIENCE, 231 of objects is, that the eye does not represent to our mind one object alone, but at the same time all those that are placed betwixt us and the principal object, whose distance we are considering; and the more this distance is divided into sepa- rate and distinct parts, the greater it appears to be. For this reason, distances upon uneven surfaces appear less than upon a plane; for the inequalities of the surface, such as hills, and holes, and rivers, that lie low and out of sight, either do not appear, or hinder the parts that lie behind them from appear- ing ; and so the whole apparent distance is diminished by the parts that do not appear in it. This is the reason that the banks of a river appear contiguous to a distant eye, when the river is low and not seen. How much narrower does a river that is subject to the influence of the tide appear at low water, than when its bosom is proudly swelled at high water mark? and yet perhaps the actual breadth at both times does not vary 20 feet. ... DISTANCE, in Navigation, is the number of miles or leagues that a ship has sailed from one point to another. - Line of Dist ANce, in Perspective, is a right line drawn from the eye to the principal point of the plane. Point of DistANce, in Perspective, is that point in the horizontal line which is at the same distance from the principal point as the eye is from the same. DISTANCE of the EYE, in Perspective, is a line drawn from the eye to the principal point. DISTEMPER, in Painting, a term used for the working up of colours with something besides water or oil. If the colours are prepared with water, that kind of painting is called limning; and if with oil, it is called painting in oil, and simply painting. If the colours are mixed with any glutinous or unctuous matter instead of oil, it is said to be done in distemper. ..In this man- ner the cartoons at Windsor are painted. DISTICH, a couplet of verses making a complete sense. Thus hexameter and pentameter verses are disposed in distichs. DISTILLATION. Under the article CHEMISTRY, we ex- plained what distilling means, and how it is performed; the subject of the present article is confined to the making of ardent spirits, or alcohol,-the distillation of gases belonging to another part of our work. Previously to the operation of distilling, those of brewing and fermentation are necessary; the liquid must be brought into the state of wine, or beer, (which is the wine of grain.) Methods have been suggested, and we believe carried into prac. tice, for reducing the brewing and fermentation to a single operation, by which, it is said, the spirit is much improved in quality, as well as augmented in quantity. The practice, we are informed, is as follows:– - To one hundred pounds of malt, reduced to fine meal, are added thirty pounds of wheat meal; twenty gallons of water are then added by degrees, mixing the whole mass thoroughly: fifty gallons more of water, made boiling hot, are then poured upon the mass, and the whole well stirred together. It is then allowed to stand for two hours, afterwards stirred again, and when grown cold, a pound or more of solid yeast is added, and then allowed to stand loosely covered in rather a warm place to ferment. - In London, and its neighbourhood, we understand the pro- cess of forming the wash for distillation is the same as in brewing for beer, with the exception of the addition of the hops, and that instead of boiling the wort, they pump it into coolers, and afterwards draw it into backs, to be then fermented with yeast. During the fermentation, particular attention must be paid to the temperature of the liquid: if it exceeds 770 Fahrenheit, the fermentation will be too rapid; if below 600, the fermentation will cease. The mean between these is consi- dered the most favourable, and the fermentation must be con- | tinued until the liquor grows fine and pungent to the taste, but not so long as to permit the acetous fermentation to commence. In this state the wash is put into the still, of which it should occupy about three-fourths, and distilled with a gentle fire, as low as any spirit comes over, which is generally until about half the wash is consumed. The form of the common still is too well known to need any particular description; it generally consists of a large boiler made of copper, and fixed in masonry over a fireplace; the * ends a little above the surface. boiler has a head, or capital as it is called, which is of a globu- lar form, to which is soldered a neck, which forming a complete arch, curves downward, and fits into what is called the worm. The worm is a long tube, made generally of pewter, of a gradually decreasing diameter, and is curled round into a spiral form ; it is enclosed in a tub, which is kept filled with cold water during distillation. The Dutch method of making Geneva is said to be as fol. lows:–“ One hundred weight of malt from barley, and two hundred weight of rye meal, are mashed, with four hundred and sixty gallons of water, heated to 162°Fahrenheit. When the infusion has been continued a sufficient time, cold water is added until the wort is equivalent to about forty-five pounds of saccharine matter per barrel; it is then drawn off into a back of five hundred gallons’ capacity, at the temperature of 80°, with half a gallon of yeast. The fermentation immediately commences, and is generally finished in about two days, when proper attention is paid to the temperature of the place. The wash is then put into the still, reduced to about fifteen pounds of saccharine matter per barrel, along with the grains, and receives three distillations, a few juniper berries, and a small quantity of hops, being introduced to communicate the flavour required.” The spirits of the first distillation is usually called low wines; the re-distillation of the low wines, or doubling, produces at first a fiery spirit, milky and crude, (which is returned into the low wines); after this the spirit flows perfectly clear and bright; nevertheless, tainted a little with empyreuma, to get rid of which it generally undergoes another distillation called rectifi- cation, at which time flavouring ingredients are added, to imitate the foreign spirits, such as rum, brandy, hollands, gin, &c. and likewise to form the compound spirits, called cara- way, peppermint, cinnamon, cloves, aniseed, &c. The flavour of malt spirit is said to be much improved, by putting four ounces of finely-powdered charcoal, and four ounces of ground rice, into a quart of spirits, and letting it stand for a fortnight, frequently stirring it; upon being then strained, it will be found to resemble very closely the flavour of brandy. It has been frequently proved, that the muriate of soda (or common salt) thrown into the still in the proportion of about half an ounce to every gallon, will materially improve the taste and strength of the spirit; the viscid matter being fixed by the salt, allows the volatile parts to ascend in greater purity. Some time since, a distiller at Copenhagen published an account of his having several times distilled brandy and gin from wheat steeped in salt water, by which he uniformly obtained nearly one-fourteenth more of spirit, than when he distilled from an equal quantity of wheat, which had not under- gone that process. - It is said to be the practice of the distillers in Scotland, &c. to use one part of malted grain, with from four to mine parts of raw grain; rye is said to produce more spirit than wheat, and wheat more spirit than barley. - WINTER’s Distilling Apparatus, exhibited in the annexed figures, is constructed on the principle of condensing the aqueous portion of the mixed liquor previously to its passing into the still. A, in this sectional view, is a tube by which the va-. pours enter from the still into B the receiver. C is a conical plate. D the chief vapour tube, which being closed at the top, the va- pours descend by the small tubes G, into the chamber F. The ap- paratus is isolated in water of 170° temperature, contained in the tub or bath T, and as the vapours contained in the tubes are by this arrangement separated into small portions, a rapid con- densation takes place. A num- ber of circular tubes, as at H, are fixed in the plate which covers the receiver B, with their upper These carry off the condensed liquor into the receiver B. The vapour, now improved in its spirit, is collected in the chamber F, and passes by the tube I 2B2 D 1 S, D I V DICTIONARY OF MECHANICAL SCIENCE, into the second receiver K. The top plate of this second receiver K, as well as the bottom plate of the third receiver N, have numerous apertures of concentrie circles as at L L, in the following figure, into each of which are fitted two copper cylinders, one within the other, and only about a quarter of an inch apart. And as there are four such apertures, there are consequently eight pairs of apertures. Into each of these annular apertures L., L, are fixed two copper cylinders, one within the other, and only about a quar- ter of an inch apart ; and as there are four such apertures, there are consequently eight cylinders or four pairs in the apparatus, which are exhibited in section in the first engraving at M, M. O, O are tubes which pass through the receiver K, to convey water between the cylinders; similar tubes are passed through the receiver N, by which means the water is diffused over every part of the extended surface of the apparatus, effecting thereby almost as rapid a condensation of the aqueous portion of the vapour, as if the water were in actual contact with it. The vapours passing from the lower receiver K, ascend, as before mentioned, through the narrow spaces between the cylinders into the upper receiver N, in a high state of purity and strength; from this last hold it proceeds into the worm by the tube P, where it is instantly condensed by the refrigerating effect of the cold water with which this part of a distillatory apparatus is always surrounded. . . - It is, perhaps, not unnecessary to repeat, that the water con- tained in the second bath T, shewn in section, is heated to 140° (or less, as the spirit may be required,) that being a degree of temperature to which the vapour of water, as well as those from the empyreumatic oils, cannot exist. The spirit is thus sepa- rated effectually, and without any difficulty, from the least taint of empyreuma, with which British spirits are in general more or less. contaminated. It will be observed, that this second receiver is of a peculiar construction, and being kept at a temperature of 140°, the whole of the weaker vapour is therein reduced into a liquid state, while the strong spirituous vapour, ascending alone through certain very narrow spaces, contained between the circuitous cylinders, into the deeper part of the apparatus, is thence collected into a third receiver previously to its passing into the worm. The worm is surrounded as usual with cold water, whose powerful refrigerating effects upon the strong spirituous vapour with which it is charged, causes it rapidly to pass into a fluid state. * or flavoured, by allowing the vapours to pass through the necessary ingredients as they pass on to the worm. We need not speculate on the advantages"of this apparatus, which is manufactured by Messrs. Pontifex, Sons, and Co. London. Disti LLATION by a low heat, in close'vessels. Those who are acquainted with the common method of distilling, know that a very unpleasant flavour accompanies all distilled products, occasioned by the matter in the still being overheated, or || burned. The late James Watt ascertained, that liquids boiled at a very low temperature in vacuo, or by emptying the appa- ratus of atmospheric air; and Mr. Tretton, of Whitechapel, London, ingeniously applied this fact to distillation, and con- structed the annexed apparatus, wherein the body of the still is seen as immersed in a water bath, which renders it impossi- ble to overheatgr burn the liquid, or communicate the disagree- able empyreumatic flavour to spirit, as is done by the common still. A is the body of the still ; B is a water bath, into which the body of the still is immersed; C is the head, or capital; D is the neck of the same, which, curving downwards, is connect- ed with a pipe that enters the condensing vessel E ; F is a refrigeratory, , or close vessel, containing cold water, for con- verting into liquid the spirituous vapours, which having been raised in the still, are contained in the vessel. E. Frºm the bottom of the vessel E a pipe issues for conveying the liquid, and the vapour not yet condensed, into vessel G, which being surrounded with cold water contained in the vessel H. acts also as a refrigeratory, and reduces the whole of the remaining vapour into a liquid state. I is an air-pump for effecting a vacuum in the vessels A. E. G. K is a stop-cock for cutting off the communication between the vessels E and G, when the contents of G are drawn off by the cock M, by which means a vacuum is preserved, during that operation in the vessel E and the still A; L is an air-cock, to admit air into vessel G, to allow the contents to run out at M ; N is a discharge-cock to the still A. - - & – The pressure of the atmosphere being removed from the surface of the liquid by the air-pump, the distillation is effected at a temperature of 1320 in place of 212°, and of course from the regular application of so low a degree of heat, an agreeable flavour is secured to the distilled product. Moreover, from the distiliation being confined throughout the operation to close vessels, the common loss by evaporation at the end of the worm is avoided, and an increase of product is obtained. DISTINCT Base, in Optics, is the same with what is other- wise called the focus. • - - DISTINCTION, in Logic, is an assemblage of two or more words, whereby disparate things, or their conceptions, are denoted. There are three kinds of distinctions, taken from the three different modes of existence, real, inodal, and rational. The first is that between two substances, or the modes of two substances. The second is that between several things, one whereof may exist without the other, but not vice Versa. The third is that between several things which are really one and the same, and whereof one cannot exist without the other; nor, vice versa, the other without this; such is that between a thing and its essence, between the essences and properties, &c. DISTRESS, in Law, is the taking of a personal chattel, out of the possession of the wrong doer, into the custody of the person who is injured, to procure a satisfaction for the wrong Łommitted. It is of two kinds; cattle for trespassing and doing damage, or for the non-payment of rent or other duties. But the most usual injury for which a distress may be taken, is that of non-payment of rent. - DISTRING AS, in Law, a writ commanding the sheriff, or other officer, that he distrain a person for debt to the king, &c. or for his appearance at a certain day. There is a great diver- sity of this writ. i) ITTON, HUMPHREY, a mathematician of the seventeenth century, born at Salisbury, May 29, 1675, was author of several * * * * * * * * * tº a º tracts which were published in the Philosophical Transactions. In this still the spirit might be rectified DIVERGENT, tending to various parts from one point; thus we say, diverging lines, rays, &c, meaning those lines or rays which issuing from one common point, go off from that point in various directions. DIVERGING SERIEs, in Analysis, are those series, the terms of which increase more and more, the farther they are continued. DIVERSITY, in Painting, consists in giving every part or figure in a piece its proper air and attitude. - DIVIDEND of Stocks, is a share or proportion of the interest of stocks erected on public funds, as the South Sea, &c. divided among, and paid to, the proprietors half yearly. DIVIDEND, in Arithmetic, is that number which is to be divided by some other number called the divisor. - DIVING, the art of descending under water to considerable depths, and remaining there for some time in order to recover things which have been sunk, as also for the purpose of bring- ing up corals, pearls, sponge, &c. - - D I V D 1 v '333 DICTIONARY OF MEGHANICAL SCIENCE. Diving Bell, an apparatus used for the purpose of diving. See BELL. * There have been various engines contrived to render the business of diving safe and easy ; the great point, is to furnish the diver with fresh air, without which he must either make but a short stay or perish. Those who dive for sponges in the Mediterranean, carry down sponges dipped in oil in their mouths. But considering the small quantity of air that can be contained in the pores of a sponge, and how much that little will be contracted by the pressure of the incumbent water, such a supply cannot subsist a diver long, since a gallon of air is not fit for respiration above a minute. Dr. Halley assures us, a naked diver cannot subsist above two minutes under water with or without a sponge; besides, if the depth be considerable, the pressure of the water makes the eyes blood-shot, and frequently occasions a spitting of blood. An experiment was lately tried at Rouen upon a new invent- ed diving machine, called batteau-poisson, or fishboat. This boat sunk of itself seven or eight minutes, and then rose of itself. The longest time it remained under water was eight minutes. The descent into the inside of this machine was by an opening made in the form of a tunnel, which was about a demimetre above the surface of the water. When those who conducted the experiment wished to descend altogether in the river and disappear, they let down this opening, sunk entirely under the water, and lost all communication with the external air. The inventor of this ingenious machine was Fulton. Three of his assistants went into the boat, and remained during the experiment. The prefect and a vast concourse of specta- tors were present. Divi NG Bludder, is a term used by Borelli, for a machine which he contrived for diving under the water to great depths, with great facility, and which is preferred to the common diving bell. The vesica, or bladder, as it is usually called, is to be of brass or copper, and about two feet in diameter. This is to contain the diver’s head, and is to be fixed to a goat-skin habit, exactly fitted to the shape of the body of the person. Within this vesica there are pipes, by means of which a circu- lation of air is contrived; and the person carries an air-pump by his side, by means of which he may make himself heavier or lighter, as the fishes do, by contracting or dilating their air bladder. - - DIVISIBILITY, an essential property of bodies. Every substance with which we are acquainted is capable of being separated into parts, and each of these again repeatedly sub- divided. Nor has any limit ever been assigned to this pro- cess of continual subdivision, though it seems probable that, at some term, however distant, the resulting particles may lapse into simple atoms, incapable of any farther resolution. The actual subdivision of bodies has, in many cases, been carried to a prodigious extent. A slip of ivory, of an inch in length, is frequently divided into an hundred equal parts, which are distinctly visible. But, by the application of a very fine screw, five thousand equidistant lines, in the space of a quar- ter of an inch, can be traced on a surface of steel or glass with the fine point of a diamond, producing delicate iridescent colours. Common writing paper has a thickness of about the 500th part of an inch ; but the pellicle separated from ox-gut, and then doubled to form gold-beaters’ skin, is six times thinner. A single pound of cotton has been spun into a thread 76 miles in length; and the same quantity of wool has been extended into a thread of 95 miles; the diameters of those threads being hence only the 350th and 400th parts of an inch. But the ductility of some metals far exceeds that of any other substance. The gold-beaters begin with a riband an inch broad and 150 inches long, which has been reduced, by passing through rollers, to about the 800th part of an inch in thickness. This riband is cut into squares, which are dis- posed between leaves of vellum, and beat by a heavy hammer, till they acquire a breadth of more than three-inches, and are therefore extended ten times. These are again quartered, and placed between the folds of gold-beaters’ skin, and stretched out, by the operation of a lighter hammer, to the breadth of five inches. The same process is repeated, sometimes more than once, by a succession of lighter hammers; so that 376 grains of gold are thus finally extended into 2000 leaves, of 3.3 25. inches square, making in all 80, books, containing each 25 leaves. The metal is consequently reduced to the thinness of the 282,000th part of an inch, and every leaf weighs rather less than the fifth part of a grain. * Silver is likewise capable of being laminated, but will scarcely bear an extension above half that of gold, or the 150,000 part of an inch thick. Gopper and tin have still infe- rior degrees of ductility, and cannot perhaps be beat thinner than the 20,000th part of an inch. These form what are called T)utch Leaf. - In the gilding of buttons, five grains of gold, which is applied as an amalgam with mercury, is allowed to each gross; so that the coating left must amount to the 110,000th part of an inch in thickness. If a piece of ivory or white satin be im- mersed in a nitro-muriate solution of gold, and then plunged into a jar of hydrogen gas, it will become covered with a sur- face of gold hardly exceeding in thickness the ten millionth part of an inch. - .. The gilt wire used in embroidery, is formed by extending gold over a surface of silver. A silver rod, about two feet long and an inch and half in diameter, and therefore weighing nearly twenty pounds, is richly coated with about 800 grains of pure gold. In this country the lowest proportion allowed is 100 grains of gold to a pound of silver. This gilt rod is then drawn through a series of diminishing holes, till it has stretched to the vast length of 240 miles, when the gold has consequently become attenuated 800 times, each grain covering a surface of 9600 square inches. This wire being now flatted, the golden film suffers a farther extension, and has its thickness redubed to the four or five millionth part of an inch. - - It has been asserted, that wires of pure gold can be drawn of only the 4000th part of an inch in diameter. ..] Wollaston, by an ingenious procedure, has lately advanced much farther. Taking a short cylinder of silver, about the third part of an inch in diameter, he drilled a fine hole through its axis, and inserted a wire of platinum only the 100th part of an inch thick. This silver mould was now drawn through the successive holes of a steel plate, till its diameter was brought to near the 1500th part of an inch, and consequently the inter- nal wire, being diminished in the same proportion, was reduced to between the 4 and 5600th part of an inch. The compound | wire was then dipped in warm nitric acid, which dissolved the silver, and left its core, or the wire of platinum. By passing the incrusted platinum through a greater number of holes, wires still finer were obtained, some of them only the 30,000th part of an inch in diameter. The tenacity of the metal, before reaching that limit, was even considerable ; a platinum wire of the 18,000th part of an inch in diameter supporting the weight of one grain and a third. , . . - Such excessive fineness is hardly surpassed by the filamen- tous productions of nature. Human hair varies in thickness, from the 250th to the 600th part of an inch. The fibre of the coarsest wool is about the 500th part of an inch in diameter, and that of the finest only the 1500th part. The silk line, as spun by the worm, is about the 5000th part of an inch thick; but a spider's line is perhaps six times finer, or only the 30,000th part of an inch in diameter, insomuch, that a single pound of this attenuated substance might be sufficient to encompass our globe. - The red globules of the human blood have an irregular roundish shape, from the 2500th to the 3300th of an inch in diameter, with a dark central spot. * The trituration and levigation of powders, and the perennial abrasion and waste of the surface of solid bodies, occasion a disintegration of particles, almost exceeding the powers of computation. Emery, after it has been ground, is thrown into a vat filled with water, and the fineness of the powder is dis- tinguished by the time of its subsidence. In very dry situ- ations, the dust lodged near the corners and crevices of ancient buildings is, by the continual agitation of the air, made to give a glossy polish to the interior side of the pillars and the less prominent parts of those venerable remains. So fine is the sand on the adust plains of Arabia, that it is carried some- times 300 miles over the Mediterranean, by the sweeping and violent Sirocco. Along the shores of that sea, the rocks are peopled by the pholas, a testaceous and edible worm, which, 3 O But Dr. W. H. . . 234 D I V D I V IDICTIONARY OF MECHANICAL SCIENCE, though very soft, yet, by unwearied perseverance, works a cylindrical hole into the heart of the hardest stone. The mar- ble steps of the great churches in Italy are worn by the inces: sant crawling of abject devotees; nay, the hands and feet of bronze statues are, in the lapse of ages, wasted away by the ardent kisses of innumerable pilgrims that resort to those shrines. What an evanescent pellicle of the metal must be abraded at each successive contact: tº The solutions of certain saline bodies, and of other coloured substances, exhibit a prodigious subdivision and dissemination of matter. A single grain of the sulphate of copper, or blue vitriol, will communicate a fine azure tint to five gallons of water. In this case the copper must be attenuated at least ten million times; yet each drop of the liquid may contain as many coloured particles, distinguishable by our unassisted vision. A still minuter portion of cochineal, dissolved in deliqueate pot- ash, will strike a bright purple colour through an equal mass of water. - Odours are capable of a much wider diffusion. A single grain of musk has been known to perfume a large room for the space of twenty years. Consider how often, during that time, the air of the apartment must have been renewed, and have become charged with fresh odour ! . At the lowest com- putation, the musk had been subdivided into 320 quadrillions of particles, each of them capable of affecting the olfactory organs. The vast diffusion of odorous effluvia may be con- ceived from the fact, that a lump of assafoetida, exposed to the open air, lost only a grain in seven weeks. . Yet, since dogs hunt by the scent alone, the effluvia emitted from the several species of animals, and from different individuals of the same race, must be essentially distinct. - The vapour of pestilence conveys its poison in a still more subtile and attenuated form. The seeds of contagion are known to lurk for years in various absorbent substances, which, on exposure to the air, scatter death and consternation. But the diffusion of the particles of light defies all powers of calculation. A small taper will, in a twinkling, illuminate the atmosphere to the distance of four miles; yet the luminous particles which fill that wide concavity cannot amount to the 5000th part of a grain, which may be the whole consumption of the wax in light, in smoke, and ashes. Animated matter likewise exhibits, in many instances, a wonderful subdivision, Between the Tropics, the small marine polypi, by the immensity of their combined numbers, speedily raise up clusters of coral reefs, so dangerous at present to the navigation of those seas, but which are destined, at no very remote period, to form groups of inhabited and cultivated islands. The milt of a codfish, when it begins to putrefy, has been computed to contain a billion of perfect insects; so that thousands of these living creatures could be lifted on the point of a needle. . But the infusory animalcules display, in their structure and functions, the most transcendent attenuation of matter. The vibrio undula, found in duck-weed, is computed to be ten thousand million times smaller than a hemp seed. The vibrio lineola occurs in vegetable infusions, every drop containing myriads of those oblong points. The monas gelati- mosa, discovered in ditch-water, appears in the field of a micro- scope a mere atom endued with life, millions of them playing like the sunbeams in a single drop of liquid. Insects have been discovered so small as not to exceed the 10,000 part of an inch, so that 1,000,000,000,000 of them might be contained within the space of one cubic inch, yet each ani- pmalcule must consist of parts connected with each other, with vessels, with fluids, and with organs necessary for its motions, for its increase, for its propagation, &c. How inconceivably small must those organs be ; and yet they are unquestionably composed of other parts still smaller, and still farther removed from the perception of our senses. DIVISION, in the Navy, a select number of ships in a fleet or squadron of men-of-war, distinguished by a particular flag, pendant, or vane, and sometimes commanded by a general officer. A squadron is commonly ranged into three divisions, the commanding officer of which is always stationed in the centre. In a large fleet the admiral divides it into three squad- rons; each of which is commanded by an admiral, and is again divided into three divisions; each squadron has its proper thus, 346)7486716 (21637 566 2207 1311 2736 proof 314 colours, according to the rank of the admiral who commands it; and each division its proper mast. The private ships carry pendants of the same colour with their respective squadrons at the masts of their particular divisions, so that the ships in the last division of the blue squadron carry a blue pendant at their mizzen top-gallant-mast-head. These distinctions of divisions are not, however, constantly practised. The general officers or commanders of divisions place themselves in the centre of the divisions, the three commanding admirals excepted, who, in a sailing position, lead their respective squadrons.--In the Army, a body of troops composed of several brigades, and commanded by a general officer. Division, in Natural Philosophy, is the taking a thing to pieces, in order to have a more complete conception of the whole : this is frequently necessary in examining very complex beings, the several parts of which cannot be surveyed at one view. Division, is one of the principal rules in Arithmetic and Algebra: it consists in finding how often a less number is con- tained in a greater. The number to be divided is called the dividend, the number by which the division is made is the divisor; the number of times that this is contained in the former is called the quotient, and if any thing remains after the opera- tion is finished, it is called the remainder. Division is either simple or compound. Ar" . Simple Division, is when both the divisor and dividend are integral numbers. Rule.—Draw a small curve-line on the right and left of the dividend, and write the divisor on the left; then find how many times the divisor is contained in as many of the left-hand figures of the dividend as are just necessary, and place that number on the right. Multiply the divisor by this number, and place the product under the figure of the dividend above men: tioned. Subtract this product from that part of the dividend under which it stands, and bring down the next figure of the dividend, or more if necessary, to the right of the remainder. Divide this number, so increased, as before, and so on till the whole is finished. Note 1. When it is necessary to bring down more than one figure to the remainder, a cipher must be placed in the quotient for every figure thus brought down. 2. If the divisor do not exceed 12, the quotient may be written down as it arises, immediately under the dividend.-Proof of Division. Multiply the divisor and quotient together, and add to this product the remainder, which ought to be equal to the dividend, if the work be right. Example. - - 5) 674346 (1 7)643287 (1 346 ) 7486716 (21637 *--> *—- . . . 692 346 134869 quotients 91898 ! 5 7 566 129822 346 86548 674346 proof 643287 64911 . 2207 314 2076 - - 7486716 proof. 1311. - 1038 2736 2422 314. Sometimes, for the sake of abridging the operation, the sug- cessive products are omitted, and the subtraction is made figure for figure as the work is carried on; by this method, the foregoing example would stand as follows:–Division may also be proved by the cross, the same as multiplication, by casting out the nines from the divisor and quotient; and again out of the product of their remainders; and this last remainder ought to be the same as that arising from the dividend, after the remainder, arising in the operation, is subtracted from it; JD I V D I V 235 DICTIONARY OF MECHANICAL SCIENCE. . This is generally called the Italian method of division. * Compound Division, is when the dividend is a compound quantity.—Rule. ... Divide the highest denomination of the dividend by the divisor, as in the former rule, Reduce the remainder, if any, to the next inferior denomination, and divide || as before ; reduce this remainder again, and divide as before ; and so on till the whole is finished. Note. If the divisor exceed 12, and be a composite number, divide by its factors successively, instead of the whole number at once. - £. s. d. £. s. d. Example. 3)4 13 9( 7) 9 13 11 ( 1 11 3 quotient 1 7 9 3 7 4 13 9 proof 9 is iſ 3. Divide £214. 14s. 10d. by 24, 24 = 4 × 6 4)314 i. #( - 6) 53 is sº 8 18 113 f Division of Fractions, is performed by the following rule. Reduce all mixed numbers to improper fractions, then invest the terms of the divisor, and multiply the numerators and the denominators together as in multiplication, observing that such factors as are common in the numerators and denomina- tors may be cancelled. - - Eramples. - . . . 1. Z-- * = 4 x * = #| 3, 1°-- *= ** x*= Z. 1. 5+ 4 = 5 × 5 = 37 s = 1 = 5 × 5 = 3 3 4 3 9 27 . . . , 1 . , 1 7 2 14 - - - - - + = + | 4, 2:--4: = + x : = +: 2, #4-5 = i < * = #|* *ā-ā- 5 × 5=; Division of Decimals, is performed the same as in the sim- ple rule of division, observing only to point off in the quotient as many decimal places, as those in the dividend exceed those in the divisor; and if there be not so many, the defect must be supplied by prefixing ciphers. Another way to know the place for the decimal point is this: the first figure of the quotient must be made to occupy the same place either in integers or decimals, as does that figure of the dividend that stands over the unit's place of the first product. Note. The division may be carried on to any extent required by annexing ciphers to the remainders after all the given figures have been used. Example. 486:4)748°6840(1.615 quotient. - 298.28 7 444 2 5800 1480 Division of Circulating Decimals, is performed by converting the repetends into their equivalent fractions, and then proceed- ing as in division of fractions. Division, in Algebra, is the method of finding the quotient arising from the division of one intermediate quantity by another, which may be considered under two cases. Case 1. When the divisor and dividend are both simple quan- tities. Rule. Divide the co-efficients, as in arithmetic, and to the quotient annex the result arising from the division of the indeterminate quantities. Note. When the divisor and divi- dend have like signs, the sign of the quotient is plus + ; and when they are unlike, the sign of the quotient is minus –, as in multiplication. - - Example, 6 a b)24 a” b” 7a.”) 3528 y? 6aº Vy)72 w8 y 4a b 5 a yº 12a: N/ y – 4a bº)32 a be” — 42 y)–162° y” - + 42 y? 4a2b) – 24 as bacº —8c — 6 a b” c” : case 2. when the dividend is a compound quantity, and the divisor either simple or compound. Rule. Set the divisor on the left of the dividend, and proceed in the operation the same as in division of numbers, observing still the same rule as above with regard to the signs. * : - - Eacamples. . - - a — b) a” — 2 a b + b (a – b a + y )wº + y” (a.”— a y + y” a” — a b ... i a!" -- a 2 y - - — a b + b% . — a.” y + y^ * a b + b2 — a.”y — a y” + a y” + y” + a y” + y” Division of Algebraic Fractions, is performed the same way as in the case of simple fractions, viz. reduce all mixed expressions to improper fractions, then invert the terms of the divisor, and multiply the numerators and denominators as in the rule above quoted, observing to cancel all factors that are common to the numerators and denominators. - Examples. 5cº 25 cº 4 ºf 5.7 FT * 3: T 12.5 2. *** - 9”z – 3:4 x 7” y' = 7 º' y' 5 a.” 2 723 y? T 5 a.” 2 9 w 2 T 1528 w a" – y' ... 2” -- y” a!" – yº 3: a ya 4 + y : * ~ *(x+y) * * + y, º acº — aſ” - +++ = <-y. - - Division of Surds, is the method of ascertaining the quotien arising from the division of one irrational quantity by another. Rule. Reduce the given surds to their simplest form, and the radical parts thus arising to like radicals; then divide the co- efficient of the dividend by the co-efficient of the divisor for the new co-efficient, and one surd part by the other for the required surd, which being annexed with its proper radical sign to the co-efficient before found, will be the answer required. Note. If the radical signs be not the same, but the quantities under them be equal, the division will be effected by subtracting the index representing the radical of the divisor from the index of that representing the radical of the dividend. - Examples. M 105 M 735 1 —º- =====# / 785 M.54 *y — 8* M 69 — , , , , 8 | JTgz = −5.7.5: = + V H = * vary _V 108 *** = & 4 = & 16 = y 2 ſ M 18 3 V 2 M 2 N/ 8 Note. When the proposed divisor is a binomial surd, con- sisting of the sum or difference of two square roots, it may be rendered rational by multiplying both numerator and denomi- nator, or, which is the same, both divisor and dividend, by the same two quantities, but connected with a contrary sign to that by which they are connected in the denominator, that is, by + when that is – ; and by —, when that is + ; because the product of the sum of two quantities multiplied by their difference, is equal to the difference of their squares. ... Thus, for example, required the quotient arising from the division of V 5 + V7 by V 13 + V 10. By the rule, ( V 5 + V 7 V 5 + V 7 V 13 — M. 10 V 13 + V 10 V 13 + V 10 T V 13 – V10 — M 65 + V 91 – 6 M 2 – M 70. * 3 Division of Ratios, or Divided Ratio, is when of four propor- tional quantities, the differences of the antecedents and con- sequents are compared either with the antecedents or conse- quents; thus, if a b : ; c.; d. — d. : c. tº- d : d. : { a - b : a : then {:I; ; ; ; ; 236 B @ (; B) O C DICTIONARY OF MECHANICAL SCIENCE, DIVISOR, is that number or quantity which exactly divides | another number or quantity, without leaving a remainder. Divisor also signifies that number by which another number is to be divided, without regard to what may remain after division. Common Divisor, in Arithmetic, is that number which will exactly divide two or more given numbers; and the greatest of all such divisors is called the greatest common divisor, or the greatest common measure. The following theorems are frequently useful in finding the divisors of numbers:—1. If the last digit of any number be divisible by 2, the whole number is divisible by 2. If the two last digits be divisible by 4, the whole number is divisible by 4. If the three last digits be divisible by 8, the whole number is divisible by 8. And gene- rally, if the last n digits of any number be divisible by 2”, the whole number is divisible by 2 . 2. If the sum of the digits of any number be divisible by 3 or by 9, the whole number is divisible by 3 or 9; and if also the last digit be even, the whole number is divisible by 18. 3. If a number terminate with 5, it is divisible by 5; and if it terminate in 0, it is divisible by either 10 or 5. 4. If the sums of the alternate digits be equal, or if one sum exceed the other by 11, or by any multiple of 11, the whole number is divisible by 11. See vol. i. p. 24, Euler’s “Algebra,” 2d English edition. . . - By means of these theorems we are enabled frequently to ascertain the divisors of numbers, but when the greatest com- mon divisor of two numbers is required, we must proceed by the following rule. To find the greatest common Divisors of two given. Numbers.- Rule. Divide the greatér number by the less, then divide the divisor by the remainder; and thus continue always dividing the last divisor by the last remainder till nothing remains, and the last divisor will be that required.—Note. If the greatest common divisor of three or more numbers be required, find the common divisor of two of them first, then of this common divisor and another of the given numbers, and so on to the last; so shall the last divisor be the greatest common divisor required. - - Examples,—Required the greatest common divisor of 7631 and 26415, 7631).26415 (3 - 22893 3522)7631 (2 7044 greatest common divisor = 587)3522(6 * - - 3522 o which number will divide both the given numbers, for 7631 26415 T557" E 13; and 557T E 45. Common DIVISOR, in Algebra, is any algebraical formula or expression, that will exactly divide two or more other alge- braical formulae, without leaving a remainder; and the greatest of such divisors is called the greatest common divisor. DIVORCE, a separation of two de facto married together, of which there are two kinds; one a vinculo matrimonii, from the very bond of marriage; the other a mensa et thora, from bed and board. TXIURETICS, in Pharmacy, such medicines as increase the discharge of urine; or which are supposed to have a power of removing obstructions in the urinary passages. DIURNAL, in Astronomy, any thing relating to the day, in opposition to nocturnal, relating to the night. - - DIURNAL Arc, is the apparent arc described by the heavenly bodies, in consequence of the rotation of the earth, DIURNAL Motion of a Planet, is the number of degrees, minutes, &c. which a planet moves in 24 hours. DuBNAL Motion of the Earth, is its rotation round its axis, the duration, of which constitutes, the natural day. This motion has generally been considered as uniform, though there have been some astronomers who have suspected a trifling irregula- rity; and the late:investigations of the French astronomers tend rather to confirm the latter hypothesis. DOCK, a broad and deep trench formed on the side of a harbour, or the banks of a river, and commodiously fitted, either to build ships, or to receive them to be repaired; these docks have generally strong flood-gates, to prevent the flux of the tide from entering the dock. There are likewise wet docks without flood-gates, where a ship can be cleaned during the recess of the tide, or between the times when the tide leaves her dry aground, and the period when it reaches her again. DOCKING A SHIP, the act of drawing her into dock, in order to give her a proper repair, cleanse the bottom, and cover it anew. See the article BREAMING. DOCKS, LoNDoN, just below the site of the Tower, and on the left bank of the Thames, were begun in 1800, and completed in 1805, at an expense of £1,500,000 sterling; at any rate the capital of the Company is a million and a half sterling: the dividend, by act of parliament, can never exceed 10 per cent. The larger dock is a rectangle, the longer sides of which run from east to west. The lower entrance is by a cut which opens into a long basin, communicating with the dock by a short canal: this is called the Wapping entranee. Higher up the river, there is another canal, which leads to the south-west angle of the dock: this is the entrance called the Hermitage, of which we give a plan, with the excellent locks by which it is: floated. . For all these details, see the Plate London Docks. The late Mr. Rennie was the engineer who prepared the plans, and directed the execution of these great undertakings. To form an idea of the importance of these works, it will be sufficient to detail some of the principal dimensions. - The Dock, properly so called, is 420 yards in length, 276 yards in breadth, and 29 feet in depth; its superficies is equal to 25 acres ; that of the basin is above two and a half acres; and if to this square be added the ground occupied by ware- houses, the sheds, and the quays, it will be found that the whole premises contain a superficies of 110 acres. With the ex- ception of those ships that trade to the East and West Indies, every vessel, whether English or foreign, may enter the Lon. don Dock, upon paying the duties, to unship their cargoes, or take in a new lading. . . . . For the convenience of business, ranges of sheds, low, and of a very simple construction, have been erected along the sides of the dock and near the edges of the quays, into which cargoes are removed. Behind these sheds, and in a parallel direction to them, stands a line of magnificent warehouses, four stories high, with spacious vaults, into which the casks are conveyed by inclined planes. These warehouses are built with regularity and solidity, but without any pretension to ornaments. Nothing, however, can be more imposing than the effect of the whole, of the grandeur of which some idea may be formed, by considering that these buildings occupy a super- ficies of 120,000 square yards. In front of the warehouses, and along the whole length of the sheds, are iron railways; others cross these at right angles, leading from the quay to the warehouses, and, in some instances, to their interior. Oblique lines of connexion facilitate the communication of the former railways with the latter. As the edges of these railways rise in a small degree only above the level of the pavement, carriages can pass over without damag- ing them, and without being impeded by them. - To the east of the dock, a range of warehouses has been built, for the reception of tobacco. Before this expensive pro- duction was stored in secure places, and defended by high walls, it was a great object of the system of plunder and fraud carried on upon the river. The first and most extensive of these warehouses, which of itself covers a space of six acres, is the work of Mr. Alexander. This distinguished architect has here made a most judicious combination of wood and iron. On the other side of a short canal, and close to this warehouse, is a second, which covers about 17,000 square yards. Its con. struction is evidently upon the same principle as the last men- tioned. But in the present instance, the idea which Mr. Alex- ander afterward followed up, is in some measure still rude, and the progress of art is very perceptible in a comparison of the two buildings. - - - - The London Docks are the grand, depôt for foreign spirits: numerous pipes of wine and brandy are kept in the vaults, which occupy the same superficies as the warehouses; these t º L to N ID 0, IN D to tº R. s. section of Enuance to the London Docks. - - -- cround Plan of the lock with G. T-4 ºw- ºr ºt. - - - -º no º 70 *o go awº aw and cales of the Lºndon Docks Masonry. (Ground lºan- Irºn Sheds built by J. Remme at the West India Docks. ºne ºf ºr or ----- º Elevation. Zºº ºr - - - - - - -- - - - - - IB O C . D O D 237 DíCTIONARY OF MECHANICAL SCIENCE. vaults are groined, and their piers support the columns of the warehouses above. - • The London Docks have their several parts perfectly adapted to each other, and are of the most admirable construction. The gates, like all those whose size exceeds from 20 to 23 feet, in- stead of being straight, are curved on the side on which the water presses. Another very important difference observable between the hydraulic architecture of the English and that of the French, is the form of the walls of their quays. The French give the exterior face of these walls the straight form of an inclined plane, while the interior face, or that which is in contact with the ground, is in the form of a vertical plane. The English give both these faces a curved form, beginning almost perpendicu- larly, and without a curve at the upper part ; the curvature increases, and takes a sloping direction, which is less rapid as. it approaches the lower courses of the work. In works exe- cuted with great care and precision, these courses, instead of being horizontal, are perpendicular to the exterior surface of the wall. - The West India Docks are on the left bank of the Thames, at the distance of about one mile and a half below the London Docks; they are situated on the base of a tongue of land of the Isle of Dogs, a sort of peninsula formed by a long circuit of the river. The docks have an entrance at cach extremity of this circuit. is the city canal, by means of which the long turn of the river may be avoided. But in order to gain the advantage offered by the canal, a toll is to be paid. Naval captains prefer fol- lowing the common course of the river, which, when the tide serves, does not occasion a loss of more than two hours’ time. it has been found more advantageous to make this canal serve as a receptacle for dismantled ships laid up in ordinary; they are ranged on a line of about a mile in length, and present a magnificent sight when viewed from the right bank of the river. The West India docks are much superior to the London both in extent and regularity. These vast works were un- dertaken and executed by an association of private indivi- Hals, and by means of a mere subscription; twenty-seven months suſſiced to accomplish the whole. The excavations of the West India docks began on the 12th of July, 1800; and as early as the month of September, 1802, vessels entered the import dock At the highest tides the depth of water in the two docks is twenty-four feet; they are formed parallel to each other; their common length is about 890 yards. The largest, which has a superficies of above thirty acres, is destined to those vessels returning to the West Indies, which deposit their cargoes in the warehouses of this artificial port. The second, the super- ficies of which is about twenty-five acres, receives the vessels laid up in ordinary, or taking the outward bound cargoes. These docks, with their basins, and the locks which connect them with the river, present an area of sixty-eight acres of ground, excavated by human hands, for the reception and moorage of vessels: the total superficies, including that of the quays and warehouses, is 140 acres. During the busy season, this establishment employs about 2600 workmen. . It can admit at the same time 204 vessels in the import, and 195 in the export dock, forming a total of 120,000 tons. During the first fifteen years, 7,260 vessels entered them. In fine, upon the quays, under the sheds, and in the warehouses, there have been deposited at the same time 148,563 barrels or casks of sugar, 70,875 barrels and 433,648 bags of coffee, 35,158 pipes of rum and Madeira wine, 14,021 logs of mahogany, 21,350 tons of logwood, &c. Nothing ap- pears more simple than the idea of forming separate docks for the loading and unloading of importations and exportations, yet, infinite as the advantages which it affords are, in prevent- ing confusion, and the frauds which it naturally produces, the |English constructed docks for more than a century before the idea of separate docks struck them. At the upper and lower entrances of the two docks, a basin presents three locks of communication. The first communi- cates with the Thames. The water is kept in it by means of double gates. The second and third locks lead respectively into the export and import docks; they have also double gates. 26. South of the docks, and parallel to their length, ge By this means, the vessels are able to come in and go out in- dependently of the state of the tide; they may remain in the basin as long as is judged convenient. The water of the docks being but very little higher than that of the basins, it does not press violently on the gates of the locks. It should be also observed, that this water having had time to settle in its pre- vious passage through the basin, hardly deposits any sediment when introduced into the docks. The docks lie in the direction of west to east, inclining a little towards the south. The principal entrance, that of the im- port dock, is in the midst of the smaller side to the west, which faces London; in coming from the city, we reach it by a branch of the Commercial Road. - William Jessop furnished the plans of the West India docks, and directed their execution—a monument which will per- petuate his memory. The construction which we have de- scribed, in speaking of the London dock, as to quays with concave linings, lock-gates forming a sweep, and iron bridges, was first put in practice in the establishment now under con- sideration. After the death of William Jessop, all these works were intrusted to J. Rennie, sch. The sheds represented in our Plate, run parallel with the warehouses. The columns supporting them are eleven feet high, of cast iron, as are also the capitals; the construction of these roofs is very simple, but firm and neat. - The East India Docks belonging to the East India Com- pany, are inferior to the West India docks in magnitude, but equal in point of construction, security of property, and, having to receive vessels of 2500 tons, they are deeper than the West India docks, and have never less than 23 or 24 ſect water. DOCK-YARDS, arsenals containing all sorts of naval stores and timber for ship-building. In England the royal dock-yards are at Chatham, Portsmouth, Plymouth, Deptford, Woolwich, and Sheerness, where his majesty’s ships and vessels of war are generally moored during peace, and such as want repair- ing are taken into the docks, examined, and refitted for service. These yards are generally supplied from the northern crowns, with hemp, pitch, tar, rosin, canvass, oak plank, and several other species of stores. With regard to the masts, particularly those of the largest size, they are usually imported from New England. The three first of these yards are governed by a commissioner resident at the port, who superintends all the musters of the officers, artificers, and labourers, employed in the dock-yard and ordinary : he also controls their payment thercin, examines their accounts, contracts and draws bills on the navy-office to supply the deficiency of stores ; and, finally, regulates whatever belongs to the dock-yard, maintaining due order in the respective offices. # DOCTOR, a person who has passed all the degrees of a faculty, and is empowered to teach or practise the same : thus we say, doctor in divinity, doctor in physic, doctor of laws. * DODECAGON, in Geometry, a regular polygon, consisting of twelve equal sides and angles. {-} To inscribe a Dodecagon in a Circle.—Apply the radius of the circle six times round the circumference, which will divide it into six equal parts; then bisect each of those parts, which will divide the circumference into 12 parts for the dodecagon required. - To find the Area of a Bodecagon.—If the side of a dodecagon be 1, its area is equal to 3 + tan. 75° = 3 (2 + V 3) = 11, 1961524 nearly : and as the areas of polygons are to each other as the square of their like sides, we have as 12: 11:1961524:: s?: s? -- 11:1961524 – the area of a dodecagon. DO DECAHEDRON, in Geometry, one of the regular Pla- tonic bodies, comprehended under 12 cquai sides or faces, each of which is a regular pentagon. Or, a dodecahedron may be conceived to consist of J2 equal pentagonal pyramids, whose vertices or tops all meet in one common point, which will be the centre of the sphere circumscribing the dodecahedron. The side of a dodecahedron, inscribed in a sphere, is equal to the greater part of the side of a cube inscribed in the same sphere, when cut in extreme and mean proportion. If a line be cut in extreme and mean ratio, and the less part of it be taken for the side of a dodecahedron, the greater part will be the side of a cube inscribed in the same sphere. The side of the cube is equal to the right line that subtends the angle of the pentagon, 3 P £38 MD O M D O N HDICTIONARY OF MEGHANICAL SCIENCE, which forms one of the equal sides of the dodecahedron, inscribed in the same sphere. - - DODECATEMORY, the twelfth part of a circle. The term is chiefly applied to the twelve houses, or parts, of the zodiac, of the primum mobile, to distinguish them from the twelve signs; though some authors use the same term when speaking of the twelve signs of the zodiac, because they each contain a twelfth part of the whole circle. . DOG, a sort of iron hook or bar with a sharp fang at one end, so formed as to be easily driven into a piece of timber; it is used to drag it along by means of a rope fastened to it, upon which any number of men can pull, and so draw the plank towards the place where it is to be stowed. It is also used for the same purpose in unlading the ship. DOGGER, a Dutch vessel navigated in the German ocean; it is equipped with two masts, a main and a mizzen-mast, and somewhat resembles a ketch. It is principally used for fishing on the Dogger Bank. DOG-VANE, a small vane composed of thread, cork, and feathers, fastened on the end of a half-pike, and placed on the weather gun-wale to steer the ship by, when sailing on a wind. DOLICHOS, a genus of the decandria order, in the diadel- phia class of plants; and in the natural method ranking under the 32d order, papilionaceae. There are 38 species, the most remarkable of which, the soja, a native of Japan, grows with an erect, slender, and hairy stalk to the height of about four feet. The leaves are like those of the garden kidney bean. The flowers are of a bluish white, and produced from the bosom of the leaves, and succeeded by bristly hanging pods resem- bling those of the yellow lupin, which commonly contain two, sometimes three, large white seeds. There is a variety of this kind, with a small black fruit, which was once employed in medicine. Kempfer affirms, that the seeds of this give relief in the asthma. From this plant comes the pickle called sooju or soy; to make which, they take equal quantities of the beans boiled, barley or wheat roughly ground, and common salt. Having properly mixed the beans with the pounded corn, they keep the whole covered in a warm place, in order to ferment; then putting the mass into a pot, they cover it with the salt, pouring over the whole two measures and a half of water. This they stir for two or three months, at the end of which time they filtrate and express the mass, and preserve the liquor in wooden vessels. DOLLAR, a silver coinage of Spain and of the United States, the former being worth 4s. 53d. of the coinage before 1772; and 4s. 4%d. since that date; which latter is also about the value of the American dollar. . DOLOMITE. There are several kinds. White dolomite contains 46.5 carbonate of magnesia, 52.08 carbonate of lime, 6.25 oxide of manganese, 0.5 oxide of iron. It is found in beds in the island of Iona. A beautiful variety, found in the island of Tenedos, was used by the ancient sculptors. It consists of fine granular concretions. The brown dolomite is the magnesian himestone of Tennant. There is a columnar dolomite of a pale grayish white. Compact dolomite is of a snow-white colour. DOLPHIN, or DELPHINUs, in Astronomy, the Dolphin, one of the old constellations, which is said to have been placed among the constellations by Neptune, because by means of this fish, Amphitrite became the wife of Neptune, though she had made a vow to observe perpetual celibacy.—Boundaries and Contents. W. by Aquila, N. by Vulpecula, E. by Pegasus, and S. by Aquarius and Antinous. This constellation contains 18 | stars, five of which are of the 3d magnitude, and the rest of smaller magnitudes. Dolphin of the Mast, a kind of wreath, formed of plaited cordage, to be fastened occasionally round the mast as a sup- port to the puddening; the use of which is to sustain the weight of the fore and main yards by the jears, in case the rigging or chains, by which those yards are suspended, should be shot away in the time of battle. - DOME, in Architecture, is a roof, or vault, rising from a circular, elliptic, or polygonal base, or plane; with a convexity outwards, or a concavity inwards, in such a manner, that all the horizontal sections made by planes will be similar figures round a vertical axis. Domes are denominated by the figures of the basis on which they are erected; and are thereforecalled polygonal, circular, or elliptic domès, Circular domes afé ºf several kinds, as spherical, spheroidal, or ellipsoidal, hyperbo- loidal, paraboloidal, &c. Domes that rise higher than the radius of the base are called surmounted domes; and those which rise less than this dimensien, are termed diminished or surbased domes. Domes that rise from circular bases are called also cupolas. s - DOMESDAY, or Doomspa Y-book, a very aheient record made in the time of William the Conqueror, which how remains in the Exchequer, and consists of two volumes, a greater and a less; the greater contains a survey of all the lands in thbst of the counties in England, and the less compreheads some counties that were not then surveyed. The book of domesday was begun by five justices, assigned for that purpose in each county, in the year-1081, and finished in 1086. It was of that authority, that the Conqueror himself submitted, in some cases wherein he was concerned, to be determined by it. Camden calls this book the tax-book of king William ; and it was far- ther called magna rolla. There is likewise a third book of domesday, made by command of the Conqueror; and also a fourth, being an abridgment of the other books. - DOMINICAL LETTER, in Chronology, properly called Sun- day letter, one of the seven letters of the alphabet ABCDEFG, used in almanaes, ephemerises, &c. to designate the Sundays throughout the year. In our almanacs, the first seven letters of the alphabet are commonly placed to shew on what days of the week the days of the months fall throughout the year. And because one of those seven letters must necessarily starid against Sunday, it is printed in a capital form, and called the dominical letter; the other six being inserted in different cht:- racters, to denote the other six days of the week. Now, sihee a common Julian year contains 365 days, if this number be divided by 7 (the number of days in a week) there will remain one day. If there had been no remainder, it is obvious the year would constantly begin on the same day of the week : but since one remains, it is plain that the year must begin and end on the same day of the week; and therefore the next year will begin on the day following. Hence, when January begins on Sunday, A is the dominical or Sunday letter for that year: then, because the next year begins on Monday, the Sunday will fall on the seventh day, to which is annexed the sevent letter G, which therefore will be the dominical letter for all that year: and as the third year will begin on Tuesday, the Sunday will fall on the sixth day; therefore F will be the Sun- day letter for that year. Whence it is evident, that the Sun- day letters will go annually in retrograde order thus, G, F, E, D, C, B, A. And, in the course of seven years, if they were all common ones, the same days of the week and dominical letters would return to the same days of the months. But because there are 366 days in a leap-year, if the number be divided by 7, there will remain two days over and above the 52 ; weeks of which the year consists. And, therefore, if the leap- year begins on Sunday, it will end on Monday; and as the year will begin on Tuesday, the first Sunday thereof must fall on the 6th of January, to which is annexed the letter F, and not G, as in common years. By this means, the leap year returning every fourth year, the order of the dominical letters is interrupted; and the series cannot return to its first state | till after four times sevea, or 28 years; and then the same days of the months return in order to the same days of the week as before. The dominical letter may be found universally, for any year of any century, thus: Divide the centuries by 4; and take twice what remains from 6; then add the remainder to the odd years above the even centuries, and their 4th. Divide their sum by 7, and the remainder taken from 7 will leave the num- ber answering to the letter required. Thus, for the year 1878 the letter is F. - For the centuries, 18 divided by 4, leave 2; the double of which taken from 6 leaves 2 again; to which add the odd years 78, and their 4th part 19, the sum 99 divided by 7, leaves I; which taken from 7, leaves 6, answering to F, the 6th letter in the alphabet. - . DONATION, an act whereby a person transfers to another either the property or the use of something, as a free gift. In order to be valid, it supposes a capacity both in the donor and D 6 W B. R. A. 989 DIGTIONARY OF MECHANICAL SCIENGE. doneč, and requires consent, accéptånce, and delivery. Civi- lians distinguish donation into pure and conditional. DONATIVE, in the Canon Law, is a benefice given by the patron to a priest, without presentation to the ordinary, and without institution or induction. : - DONJON, in Fortification, signifies a strong stower, or re- doubt of a fortress, whither the garrison may retreat, in Čásé of necessity. - e DONN, BENJAMIN, an English mathematician, lived at Biddeford, in Devonshire, in 1729. He kept a school in that town for some years, and, while theré, made a complete survey of the county, for which he received a premium of £100 from the Society for promoting Arts and Commerce. In 1796 he was appointed master of mechanics to the king. He died in 1798, leaving behind him the charācter of an ingenious and wórthy man. DORIC ORDER. See ARchitecture. DoRIC Mode, in Music, the first of the authentic modes of the ancients; its character is, to be sévère, tempered with gra- vity and joy. - DORSIFEROUS PLANts, among botanists, such as are of the capillary kind, without stalks, and which bear their seeds on the backside of their leaves. - DORSTENIA ContRAYERYA, a genus of the monogynia order, in the tetrandria class of plants; and in the natural méthod ranking under the 53d order, scabridae. There are eight species, all of them low herbaceous plants, growing in the warm countries of America and China. The root is used in medicine, under the nāme of contrayerva. It has a kind of arbihatic smell, and an astringent, warm, bitterish taste. DOUBLE-BANKED, the situation of the oars of a boat, when two opposite ones aré managed by rowers seated on the same bench or thwart; the oars are also said to be double- banked when there are two men fabouring upon each oar. DOUBLE-CAST, in Husbandry, a term used by the farmers for that method of sowing that does not dispense the necessary uantity of seeds for a piece of land at one sowing, but requires biñg over every place twice. - " – . - t DOUBLE PLEA, in Law, is where the defendant in a suit alleges two several matters in bar of the plaintiff's action, when oile of them is sufficient. - . - DOUBLING, in the Military art, is putting two ranks bf filés 6f soldiers into one. DOUBLING A CAPE, is to sail round or pass beyond it, so as that the point of land separates the ship from her former situation, or lies between her and any distant observer. - DOUBLING UPoN, in a naval engagement, the act of enclosing any part of a hostile fleet between two fires, or of eannonading it on both sides. It is usually performed by the van or rear of that fleet which is superior in number, taking the advantage of the wind, or of its situation and circum- stárices, and tacking or running round the van or rear of the enemy, who will thereby be exposéd to great danger, and can scarcely avoid being thrown into a general confusion. DOVE-TAILING, in Carpentry, is the fastening boards together by letting one piece into another, in the form of the tail of a doze. The dove-tail is the strongest of jointings, because the tenor, or piece of wood which is put into the other, goes widering to the extreme, so that it cannot be drawn out again. • * : * * . . ; DOWER, the portion which a widow hath of the lands of her husband, after his decease, for the sustenance of herself, and the education of her children. " * ? Döwer, by the Common Law, is a third part of such lands or tenºiſients whereof the husband was sole seised in fee-simple, or fee-tail, during the marriage, which the wife is to enjoy dur: | ing her life; for which there lies a writ of dower. Döweſt by Custom. This kind of dower varies according to the custom and usage of the place, and it is to be governed accordingly ; and where such custom prevails, the wife cannot wave the provision thereby made for her, and claim her thirds at common law, because all customs are equally ancient with the common law itself. BOWN-HAUL, a rope passing up along a stay, through the efingſes of the stay-sails or jib, and made fast to the upper cöröer of the sail, to pull it down when shortening sail.—Dövä- order of amphibia reptilia. * - . . & with the wings entirely distant from the forelegs. in Africa and the East Indies. - fixed to the forelegs. It is a native of America. They are harmless creatures, and feed upon flies, ants, and small insects. Hålil Tackles, a complicatión Öf tackles éñployed to pull dowii the main or fore yard in a tempest, in order tā reef the sail because the violence of the wińd prevents the weight of the yard from having its natural effect of descending.—Down all . Shests, the order given to get all the Öfficers' ànd seaméris' chests down below from off the gun-decks, when clearing the ship for an engagement.—Down all Hämmócks, the order for the sailors to carry, their hammocks down, and hang them up in their respective births in readiness to go to bed. . DOWNS, a bank or elevation of sand; which the sea gathers and forms along its shores, and which serves it as a barrier. . DöWNS, is a term applicable also tú vast träcts of Häked poor land, on which sheep are usually grâzed. . . . . . . . . Dow Ns, is particularly used for a famous rôād for ships along the eastern coast of Kent, from Dover to the North Foreland. This road has excellent anchorage, and is well defended by the castles of Sandwich, Deal, and Dover. Thé English fleets usually meet here. . . . . • . DRABLER, an additional part of a sail, sometimes laced to the bottom of a bonnet on a square sail, in sloops and schooliers. DRABLING, in Angling, is a method of catching barbels. Take a strong line of six yards, which, beforé you fastén, ti) yotir rod, must be put through a piece of lead, that if the fish bite it may slip to and fro, and that the water may somewhat move it on the ground ; bait with a lob-worm well secured, that by its motion the barbel may be enticed without suspičioſi. The best places are in running waters hear piles, or under wooden bridges, supported with oaks floated and slimy, , , , DRABS, in Salt-Works, a kind of wooden boxes for holding the salt when taken out of the boiling pan. . . . . . . . DRACHM, a Grecian coin, of the value of 73d. Drachnis also a weight containing sixty grains, thrée scruplés, of the eighth part of an ounce. - - * -" - A , º, DRACO, the Dragon, in Astronomy, représents, accordiñá to the fables of some of the poets, the monstër which j the garden of Hesperides. Others maintain, that in a wał With the giants, this dragon was opposed to Mihervá, who thréw it round the axis of the earth, before it had time to unwind its contortions. Whoever attends to the situatioh of Drâco; sūr- rounding the Pole of the Ecliptic, will percéiyé that its tortuous folds are symbolical of the oblique course of the stars. Dracó also winds around the Pole of the worfd, as if to indicaté, in the symbolical language of Egyptian astronomy, the motion of the Polé of the Equator around the Pole of the Écliptic, agree- ably to the precession of the equiñoxes and the movéâblé zodiac of the stars. The Egyptian hieroglyphic that répresented the heavens was a serpent, whose scaleš. dénotéd thé stars; and Draco was the Polar Constellation, wheff, Chaldéâ bééânié the cradle of astronomy. Thé Gréeks théréforé did fiot ifivént this constellation. t a + Boundaries and Conténts.—North by Cynosura añd Cepheus, west by Cygnus and Lyra, south by Hércules, and east, by Ursa Major. There are 80 stars in this constellation, viz. four ôf the 2d magnitude, seven of the 3d magnitude, and ten of the 4th, &c. a, situated between y in the head of Draco and a in Ursa Major, is perhaps the most brilliant star in this constella- tion. 4620 years ago, 4 in Draco was the Polir Star. a håv. ing 2099 52' 49' right ascension, and 65° 14′ 30' north declina- tion, culminates at London, agreeably to the following table: Méridian Altitude 76° 86' 40" north. Month. Culm. || Month. Culmſ. Iſ Month. Culm. - ho. mi. . # ho. mi. ho. mi. Jan. 7 15 M, May | 11 35 A. Sept. 3, 25 A. Feb. 5 0 M. June 9 30 A. Oct. § 1 35 A. March 3 15 M. || July 7 30 A. Nov. 11 40 M. April | 1 20 M. || Aug. 5 30 A. Dec. 9 30 M. DRAco, the Dragon, in Zoology, a genus belonging to the - - I. The völäns, or flying dragon; - It is found The praepos, with the wings. & DRAco Wola Ns, in Meteorology, a fiery exhalation, fre- quent in marshy and cold countries. It is most common in, summer, and though principally seen playing near the banks of rivers, or in boggy places, yet sometimes it mounts to a con- 240 D R A D R A. DICTONARY of MECHANICAL science. siderable height in the air, to the no small terror of the amazed beholders; its appearance being that of an oblong, or roundish, fiery body, with a long tail, but it does no injury. * . . . DRACUNCULI, in Medicine, small long worms, which. breed in the muscular parts of the arms and legs}ºalled Guinea-worms, being common among the natives of Guinea. The worm is white, round, and uniform, resembling white round tape. It is lodged between the interstices and mem- branes of the muscles, where it insinuates itself, sometimes exceeding five ells in length. It occasions no great pain at the beginning; but at such times as it is ready to exit, the part adjoining to the extremity of the worm, where it attempts its exclusion, begins to swell, throb, and be inflamed; this gene- rally happens about the ancle, leg, or thigh, and rarely higher. The countries where this distemper is observed are hot and sultry, liable to great droughts, and the inhabitants make use of stagnating and corrupted water, in which it is very probable that the ova of these animalculae may be contained; for the white people who drink this water are obnoxious to the disease as well as the negroes. - DRAG, a machine consisting of a sharp square frame of iron encircled with a net, and commonly used to rake the mud off from the platform or bottom of the docks, or to clean rivers. DRAGGING the ANchor, the act of trailing it along the bottom, after it is loosened from the ground by the effort of the wind or eurrent. - DRAGON'S Head and TAIL, are the nodes of the planets, but more particularly of the moon, being the points in which the ecliptic is intersected by her orbit, in the angle of about 5° 18'. One of these points is to the northward, the moon beginning then to have north latitude; and the other southward, where she commences south latitude; the former point being represented by the knot SU for the head, and the other by the same reversed, or US, for the tail. And near these points it is, that all eclipses of the sun and moon happen. DRAGon’s Blood, a gummy resinous substance, which is brought from the East Indies. It is said to be obtained from the palmajuncus draco, the calamus rotang, the dracena draco, the pterocarpus draco, and other vegetables. In the present practice of medicine, it is very little, if at all, used, either externally or internally. A solution of dragon's blood in spirit of wine, is used for staining marble, to which it gives a red tinge. . DRAG on Shell, in Natural History, a name given by people curious in shells to a species of concamerated patella or lim- pet. This has a top very much bent, and is of an ash-colour on the outside, but of an elegant and bright flesh-colour within. It has been found sticking on the back of a tortoise, as the common limpets do on the sides of rocks, and some have been affixed to harge shells of the pinna marina. DRAGOON, in Military affairs, a musketeer mounted on horseback, who sometimes fights or marches on foot, as occa- sion requires. DRAINING, the art of clearing wet and boggy lands of their superfluous moisture. Land becomes charged with moisture from two causes:—1. From water collected in the higher grounds, and filtering among the different beds of gravel and other porous materials, forming springs below, and flowing over the surface, or stagnating underneath it. 2. From rain or water lodging and becoming stagnant on the surface, from the clayey or impervious nature of the soil, or superior stratum. The first of these causes bogs, swamps, and morasses, and is the most difficult to be remedied. Springs are formed in the bowels of the earth, by water percolating through strata of a porous texture, and it continues to descend till it meets with a stratum of clay that intercepts it in its course, where, being collected in large quantities, it is forced to seek a passage through the strata of sand, gravel, or rock, that may be above the clay, following the course of them till they approach the surface of the earth, or are interrupted by any obstacle which occasions the water to rise, thus forming springs, bogs, &c. which being variously diversified, in different circumstances, produce that variety of appearances in this respect that we often meet with. This being the case, we may naturally conclude, that an abundant spring need never be expected in any country that is covered to a great depth with . sand, without any stratum of clay to force it upwards, as is the case in the deserts of Arabia; neither are we to expect an abundant spring in any soil that consists of a uniform bed of $clay from the surface to a great depth, for it must always be in some porous stratum that the water flows in abundancé ; and it can be made to flow horizontally in that only when it is sup- ported by a stratum of clay, or other substance that is equally impermeable by water. Hence the rationale of that rule so universally established in digging for wells, that if you begin with sand or gravel, &c. you can seldom hope to find water till you come to clay; and if you begin with clay, you can hope for none in abundance till you reach to sand, gravel, or rock. It is necessary that the farmer should attend to this process of nature with care, in his practice of draining bogs, and every species of damp and spouting ground. - - - DRAMA, a Poem in which the action is represented. To the Greeks we owe the invention of both forms of dramatic composition, tragedy and comedy. These exhibitions were extremely simple. The action was continued from beginning to end, without pauses or intervais; there was no change of scene; and the attention of the spectators was continually occupied by the actors. The modern stage gives wider scope to the imagination, and renders the strict observance of the unities less necessary. . The introduction of pauses by the division of acts justifies a change of scene, and also allows a longer extension of time, without any violation of probability. Thus a greater range of subjects for dramatic representation is provided, while at the same time, as the obstructions of art are removed, the mirror, if we may so express ourselves, becomes more true to nature. The poet may so construct his drama as to lead the imagination of his audience along with him, and thus may pass in review the striking events. DRAPERY, in Sculpture and Painting, signifies the repre- sentation of the clothing of human figures, and also hangings, tapestry, and curtains. - - DRASTIC, in Physic, a term applied to medicines which are potent in their operation, particularly cathartics. DRAUGHT, in Trade, called also Cloff or Clough, is a small allowance on weighable goods, made by the king to the im- porter, or by the seller to the buyer, that the weight may hold out when the goods are weighed again. The king allows 1 lb. draught for goods weighing no less than 1 cwt. ; 2 lb. for goods weighing between 1 and 2 cwt. ; 3 lb. for goods weighing between 2 and 3 cwt. ; 4 lb. from 8 to 10 cwt. ; 7 lb. from 10 to 18 cwt. ; 9 lb. from 18 to 30 cwt. or upwards. DRAUGHT, the depth of a body of water necessary to float a ship; hence a ship is said to draw so many feet of water, when she is borne up by a column of water of that particular depth for instance, if it requires a body of water whose depth is equal to 12 feet, to float or buoy up a ship on its surface, she is said to draw 12 feet water; and that this draught may be more readily known, the feet are marked on the stem and stern-post from the keel upwards. DRAUGHT-HOOKS, are large hooks of iron fixed on the checks of a gun-carriage, two on each side, one near the trun- nion-hole, and the other at the train, for the convenience of drawing it backwards or forwards. DRAWBACK, in Commerce, an allowance made to mer- chants on the re-exportation of certain goods, which in some cases consists of the whole, in others of a part of the duties which had been paid upon the importation. A still more equitable arrangement than that of drawbacks, is, to allow the merchant who imports any commodity which he may probably wish to export again, to deposit it in the king's warehouses, giving a bond for the payment of the duties, should he dispose of it for home consumption. This is called bonding, and is allowed to a considerable extent. DRAW BRIDGE, a bridge made after the manner of a door, to draw up, or let down, as occasion serves, before the gate of a town or castle. See BRIDG E. - DRAWING, may properly be defined the art of giving a correct outline of any or every subject which has existence in nature ; and it is by far, very far, the most difficult part in the formation of a picture. A correct outline will, without the assistance of any kind of shade or colour, convey to our minds the most accurate idea not only of a single subject, but of many 72. 2./2, PYTHIUs. 7 leads, 3 parts. 61minutes. A7? 7. - , , ºf **.s. , Zve 2. x APHROIDITES. T.Dixon, sculp. * 23. 32 illis.ed by Fisher. Son & Cº. Caxton London, l "p -º- D R A D R A 241 DICTIONARY of MECHANICAL scIENCE. various objects assembled together, so that we shalk be able to say, this is a correct likeness or resemblance of objects familiar to us, or of others which the mind's perception can embrace of objects which have never previously passed before its view, but which, from association, it can embody, fancy, or imagine as existing. - - - , - . - The precise time when this elegant art was first practised, cannot now be ascertained. That the earliest inhabitants of Egypt surpassed at one period all other nations in works of art, as well as in literary pursuits, no one can doubt that has dwelt upon the historic page. The remains of celestial Thebes, with her 1000 gates, and the paintings still in existence upon some of the walls of these gigantic monuments of the genius of former ages, are a convincing proof, that the Egyptians excelled the moderns in the art of fixing colours. While the paintings of more modern artists fade in a few years, and assume the sickly hue of age, theirs retain the glow and brilliancy of youth through the course of ages. But their finest specimens of drawing fall far short of the beauty and correctness of design of their successors and their rivals. The Egyptian outlines were, generally speaking, (though there are some exceptions, no doubt,) uncouth, preposterous, and unnatural : their sculp- ture also partook of these defects in the greatest possible degree; and while we gaze with almost speechless amazement at their stupendous architecture, and their ornamental statuary which adorns it—while we look with astonishment at the bril- liancy of their coloured paintings, which, remain unfaded to the present day, we look in vain for that fair proportion, beauty of design, and accurate skill, which characterize the less stupen- dous works of later artists. ... • - Greece, immortal Greece, presents us with many remains of perfection in sculpture, but her paintings and her drawings have sunk into that gulf which alike consumes the works of the learner and the proficient. That the ancient Greeks excelled in painting, as well as sculpture, many are the records; but no trace is left of the works of Phidias, and, no doubt, of many other celebrated painters, whose works were cherished and highly prized by their admiring citizens. Fancy, or imagination, has given the merit of drawing to a Grecian-lover, sitting by his mis- tress, who is supposed to have seized the idea of retaining her resemblance by tracing her likeness on a wall upon which her shadow fell. Enchanted with the thoughts of possessing that which would be to him an inexhaustible fund of happiness and ||. pleasure, he carefully sketched the outline of that face he so much admired, and from that time forward practised the art of drawing with great success, opening to his highly-gifted mental countrymen a source of perpetual pleasure, and leading eventually to the cultivation of the more sublime art of Sculp- ture. Its origin is of little importance ; our present duty is to give those instructions, or general rules, to those who wish to make it either a study or an amusement. The first class of drawing is undoubtedly that of the human figure, the most difficult to excel in, and when done well, by far the most beautiful. - Landscape is the next class, and this should include all sub- jects of natural history, according to the peculiar character of the country or scene depicted. Birds, Beasts, Fishes, Insects, Reptiles, and Flowers, present, however, individual subjects of study to attain perfection, which requires both time, labour, and experience. - In the theory of all these different minor objects, trivial as they may appear, a knowledge of Perspective is necessary. Even the wings of a butterfly when flying, and the feet of a caterpillar when crawling, must be placed in a perspective view, for the insect either to fly or walk properly. This kind of perspective is not, perhaps, to be acquired so much by rule as by eye, -but there are certain rules which may be pointed out even for these, as necessary to give them an appearance of nature. Take the wings of a butterfly, which close perpendi- cularly, for instance, when the insect is in a quiescent state. If the two back wings were not drawn a little lower than those which are nearest to the spectator, the insect would strike every eye as possessing something unnatural in its construc- tion, though the person who censured the performance might not be able to point out the defect which he blamed. *** A correct outline will portray a countenance so accurately, 26. sº that the likeness may be recognized by all who know the party represented. Of how much importance is it then to those who wish to excel in this delightful art, that they should devote their principal attemtion to drawing ; and first of all we wish to assist the student, by laying before his observation those rules and proportions which time and experience have pronounced infallible, as guides to excellence in this enchanting art. The Proportions of the Human Figure.—The head and face form the scale by which the figure is measured. A man’s height is composed of seven heads and a half, and his arms, when extended, should measure the same length from one middle finger to the other. The head should be of an egg-shaped form, rather than an oval, as shewn in the Plate, Drawing, fig. 6, No. 1 and 2. This is to be divided into four equal parts, the eyes falling upon the middle line, No. 1, which divides it into the half. See figs. 2 and 3, which will together give the proportions of every part of the body ; but it is necessary to observe, that in all these proportions some respect must be paid to the characters of the figures drawn, and that there is a difference in the propor- tions of a man and a woman, must be evident to every casual observer; and in order the better to give the learner a correct idea upon the subject, we shall subjoin a table of the propor- tions of the Apollo Pythias and the Venus Aphrodites... Length of the Head and Trunk of the Body.” APOLLO. . . VENUS. Hs. Pts. Min. Hs. Pts. Min. From the top of the head to the bottom of the chin 4 parts, or . . . . . . . . . . . . . . . . 1 0 0 1 0 . 0 ,, the bottom of the chin to the top of the . . sternum or breast-bone. . . . . . . . . . . . 0 1 7 0 1 S ,, the top of the sternum to the pit of the - stomach . . . . . . . . . . . . . . . . . . . . . . . . . , 0 3 10 0 13 6 ,, the pit of the stomach to the navel.... O 2 10 0 2 7 ,, the navel to the pubis . . . ... . . . . . . . . . 0 3 6 0 3 9 Length of the head and trunk of the body 3 3 9 3 3 6 Length of the Lower Evtremities. * From the pubis to the small of the thigh * above the patella or knee-pan . . . . . . 1 2 6 1 2 3 , the small of the thigh to the joint or sº .* middle of the knee. . . . . . . . . . . . . . . . 0 1 9 0 1 6 * ,, the joint of the knee to the small of egº the leg above the ancle. . . . . . . . . . . . I 1 9 1 2 0 } , the top to the bottom of the ancle. ..., 0 1 0 0 1 0 , the bottom of the ancle to the bottom of the heel. . . . . . . . . . . . . . . . . . . . . . . tº 0 9 0 0 9 Length of the lower extremities. . . . . . . . . . 3 3 9 3 3 6 Length of the head and trunk, as above... 3 3 9 3 3 : 6 Total length of the figures. . . . . . . . . . . . . . 7 3 6 7 3 0 Length of the Fore Arm, or Upper Ectremities. From the top of the shoulder to the elbow 1 2 3 1 2 3 ,, the elbow to the hand . . . . . . . . . . . . . . . 1 1 2 1 0 6 ,, the joint of the hand to the root of th - - middle finger . . . . . . . . . . . . . . . . . . . . . 0 1 8 0 1 6 ,, the root to the tip of the middle ſinger 0 1 10 0 1 7 Length of the upper extremities..... ... , 3 2 11 3 1 10, Breadth between the outward angles of - & the eyes . . . . . . . . . . . . . . . . . . . . . . . . . 0 1 6 0 1 - ,, of the face at the temples .......... 3 2 2 () 2 º' ,, of the upper part of the neck . . . . . . 0 2 0 0 1 11 ,, . over the shoulders. . . . . . . . . . . . . . . . 0 0 0 - 1 - 3 S ,, of the body below, the armpits ..... 1 2 5 1 1 S ,, between the nipples . . . . . . . . . . . . . . '0 C 7 0 3 8 ,, from the bottom of the chin to the : horizontal line of the nipples . . ... 1 0 7 I O I ,, of the body at the small of the waist 1 1 0 1 0 | 8 ,, over the loins, or os ilium . . . . . . . . . 1 1 3 l l 6 ,, over the haunches, or tops. of the thigh bones. . . . . ... . . . . . . . . . . . . . 1 1 5. 1 2 3 ,, of the thigh at the top . . . . . . . . . . . . . 0 3 0 0 3 1 ,, of the thigh below the middle . . . . . . 0 2 83 0 2 7 ,, of the thigh above the knee. . . . . . . . 0 1 8 0 2 0 3 Q $42 *D R A ºptOTIONARY OF MECHANICAL SCIENCE. B R A. APOLE0. vENUs. The figure of a child has been divided by artists into four, . . * * *** Min. Hººts. Min. five, or six parts, the head forming one. In drawing the head Breadth of the leg below the knee ........ O l 6 O 1 19 of a child, two circles are formed, a larger and a smaller one, ,, at the calf of the leg . . . . . . . . . . . . . . 0 2 4 0 2 3 as in fig. 7; when the head looks up, the lower circle grows ,, . below the calf ........... . . . . . . . . . 0 l 7 0 1 1.1% longer, as in fig. 5; when it looks down, it recedes, and there- , above the ancle. . . . . . . . . . . . . . . . . . . Q & 2 0 1 2 | fore must necessarily diminish, as in fig. 4. But these propor- ; , of the ancie. . . . . . • * * *e e o e º s v = • . . . . .0 l 4 0 1 3 | tions being given, some few observations still remain to be , below the anoke. . . . . . . . . . . . . . . . . . . 0 1 13 0 1 1 made. In figures which exhibit great strength and gigantic , middle of the foot.... . . . . . . . . . . . ... 0 1 4 0 1 3 form, as the Tarnesian Hercules for instance, the proportions ,, at the roots of the toes..... . . . . . . . 0 1 7 0 1 7 are not always exact. The length of the foot of figures in ,, of the arm over the biceps muscle... 0 1 8 0 1 9 general, is given as one-sixth of the figure ; but in the Hercules ,, of the arm over the elbow.......... 0 1 6 0 1 5 it is rather more, as in the Venus it is rather less. But here , of the arm below the elbow over the judgment must be called in to aid the practitioner, as in many long supinator . . . . . . . . . . . . . . . . . 0 1 10 0 1 7 || other respects it must constitute one of the chief assistants ,, of the wrist . . . . . . . . . . . . . . . . . . . . . . () 1 0 1 0 | towards perfection. , of the hand over the first joint of the . The head of the human figure is the most expressive part of thumb. . . . . . . . . . e e s tº e º e s is º e º sº e s a e 0 1 9 0 1 8 it. Every other member may indicate some one passion,-the ,, of the hands over the roots of the - head expresses them all. Next to the head, the hands are the fingers. . . . . . . . . . . . . . . . . . . . . . . . . . 0 1 7 0 1 6 || most eloquent members, and they give double effect to the mean- over the heads of the scapulate or ing of the countenance, as few examples will convince us, that shoulder blades . . . . . . . . . . . . . . . . . 1 2 0 1 1 4 they all but speak. The hands clasped, the head inclining upward, Length of both arms and hands, each of this attitude, whether the subject be standing, kneeling, or sitting, the Apollo's being 3 h. 2 p. 11 m. and the | instantly conveys to our mind supplication. The hands crossed Venus 3h. 1p. 5 m. . . . . . . . . . . . . . . . . . . 7 1 10 6 2 10 upon the breast, with the same elevation of the head, denote wrapt - devotion ; the hands clasped upon the breast, and the head Breadth between the tips of the middle - declining, denote pious resignation and submission. With the fingers of each hand when the arms are - hands, in fact, we pray, beseech, reject, invite, dismiss, im- stretched out horizontally . . . . . . . . . . . . 8 3 10 8 0 2 plore, approve, condemn, &c.; but the varying passions of the º e human face, the rapid workings of the soul, the tumultuous Side View. feelings of joy, love, anger, contempt, hate, disdain; the more Length from the top of the head to the compound feelings of jealousy, revenge, &c. these can only be - portrayed by the face. Art may happily catch some of these shoulder . . . . . . . . . . . . . . . . . . . . . . . . 1 1 8 1 I 6 #. º: expressions, but º can express but one : ,, From the top of the shoulder to the ssion at the same moment.' Hence the painter who found it loins above the hip . . . . . . . . . . . . . . I 3 8 1 1 7 | passion, a º . . . paintº ! t -- he loins to the l art of impossible to depict the workings of a father's heart, when , 23 ſº # e loins to the lower part o 1 o 2 1 2 1 | Agamemnon stood by the altar at the sacrifice of Iphigenia, f t € #. hip tº the side of the knee covered the royal mourner's face with his robe. The picture of , from the hip to the fihepatia. 1 2 o 1 o the two misers, painted by the blacksmith of Antwerp, has . . º to º: ...'. i. º t 11 most happily succeeded in expressing anxiety and joy at the ,, . from º: º € KI) 66 to the OOt- 2 0 5 2 0 II | * time in the face of the figure which is looking at the tom of the heel. . . . . . . e e s e º e º ſº e º & * . . sº spectator. There is a scintillation in the eyes which bespeaks - , , his ioy and delight at the riches before him, but his countenance Length of the figures . . . . . . . . . . . . . . . . . . . 7 3 6 3 0 is º wonderfully expressive of his miserly anxiety. Thickness from the fore to the back part Le Brun has endeavoured to give designs of all the passions, of the skull . . . . . . . . . . . . . . . . . . . . . :0 6 0 3 4 but many of his heads upon this subject appear to be carica- ... , from the rising of the nose to the tip - - tures; at any rate, the total distortion, and forced violence, of the ear . . . . . . . . . . . . . . . . . . . . . . . 0 1 8% 0 1 6 which every feature betrays in the heads designed to represent ,, . from the upper part of the neck..... 0 2 0 0 l l l jealousy, hate, horror, and many others, are undoubtedly quite , , from the breast to the back over the | overdrawn. That the same face will be hardly recognized nipples. ... . . . . . . . . . . . . . . . . . . . . . 1 0 6 1 0 6 when tranquil, to be the same when under the workings of ,, from the belly to the small of the back 0 3 6 0 3 7 violent passion, cannot be denied ; but that he has greatly out- , from the belly above the navel to the stepped nature in the transformation the passions make in the back of the loins . . . . . . . . . . . . . . . . 0 3 9 1 0 2 ‘human face divine,” is equally not to be denied. Yet it is not ,, from the bottom of the belly to the our intention to depreciate the abilities of Monsieur Le Brun, round of the hip . . . . . . . . . . . . . . . . 1 0 0 1 0 5 but merely to refer the student to the study of nature, in pre- ,, from the fore part of the thigh to the ference to the models he has left of the passions. In exhibiting bottom of the hip . . . . . . . . . . . . . . . . . i. 3 2 0 3 7 the passions, it is also necessary that the whole body should ,, of the thigh, at the middle . . . . . . . . . 0 3 3 0 3 6; bear somewhat of the same character. How ridiculous would ,, . of the thigh above the knee. . . . . . . . 0 2 1 0 2 3 it be to place a head portraying rage, upon a body in a quies- ,, at the middle of the knee below the cent state. Besides which, rage may be displayed in more patella . . . . . . . . . . . . . . . . . . . . . . . . . 0 2 1 0 2 2 ways than one. The man of ungoverned temper throws himself ,, of the leg below the knee. . . . . . . . . . 0 1 9 0 1 11 into a thousand extravagant attitudes, extends his arms, ,, of the leg at the calf. . . . . . . . . . . . . . 0 1 8 0 1 9 makes rapid strides towards the object of his anger, his face ,, of the leg at the ancle. . . . . . . . . . . . . 0 1 5} 0 1 4 || reddens, &c. But the man in whom rage may be equally ,, of the foot at the thickest part ..... 0 0 10 0 0 3 powerful, but who at the same time has acquired some degree ,, length of the foot . . . . . . . . . . . . . . . . 1 0 6 1 0 4} of self-command, becomes pale, his countenance works, but his ,, from the fore part of the bend of the - motions are rather restrained than violent: if he walks his step foot to the lower and back part of is firm, and his attitudes more terror-striking to the mind than the heel. . . . . . . . . . . . . . . . . . . . . . . . 0 0 0 0 2 2 those of the former, who excites fear for our immediate personal ,, of the arm over the biceps .... . . . . . 0 2 0 0 1 9 safety only. Again, the position of a man under the effect of ,, . over the elbow. . . . . . . . . . . . . . . . . . . . . 0 1 6 0 1 6 terror and affright, may be depicted in more ways than one. ,, below the elbow. . . . . . . . . . . . . . . . . . 0 l 5 0 1 7 | Sometimes fear deprives a man of the power of motion ; some- ,, at the wrist. . . . . . . . . . . . . . . . . . . . . . 0 1 1 0 0 11 | times he is urged to precipitate flight, and sometimes he falls , below the joint of the wrist..... ... 0 1 & 0 0 10 | prostrate to the ground. The expression of fear, as depicted ,, of the hand at the roots of the fingers 6 5% 0 .0 5 in the countenance, should agree with each of these attitudes. : ,, at the roots of the mails. . . . . . . . . . . . .0 0 .3} 0 0 3 | There should, in fact, be a unison in the whole figure; all D R A I) R. A. 243 DICTIONARY OF MEC HANICAL SCIENCE. should be harmony: and as we are surrounded by human nature, actuated by all their passions, we have now only to become close observers of what passes around us, to acquire a knowledge of which is indispensable towards the attainment of that excellence which every artist should aspire to, and which the labours of the most aged artists still find evading their But this should act as a grasp, in some one shape or another. spur to the youthful student, rather than a curb. Grace is another point of material and essential consequence for a beautiful outline ; but here again judgment must be called to our aid, for that which would constitute grace in a Venus, would be any thing but grace if given to Minerva. The atti- tude of a judge, an orator, may be graceful, but it would be folly to think for an instant that their attitude should resemble that of a young Esquimaux Indian.* In the former, animated dignity would constitute grace,—in the latter, roundness of limb, muscular strength, and a light yet firm attitude, agreeably to the pursuit he was following, whether running, standing, &c. would constitute grace. That grace of motion has always been considered as one of the leading characteristics in female beauty, we have the sanction of the sweet Mantuan poet: in the 560th line of the first book of the AEneis, he says— “And by her graceful walk, the queen of love is known.” Beauty has been considered merely ideal. That it is so partly, is true ; since the Negro and the Chinese differ as much in their ideas upon this subject, as they do with the Europeans, and other Asiatics. Yet we are not disposed to dispute with either of these nations the palm of female beauty ; the small dark eyes of the one, and their fair skin and crippled feet, or the flat nose and prominent lips of the other, have no attrac- tions for us. Every nation has a peculiar cast of countenance, and the most beautiful of the cast forms the standard national idea of beauty. If it were possible to place a beautiful woman from Italy, Spain, France, Germany, England, Holland, Cir- cassia, Georgia, &c. side by side, we should be amused and enchanted beyond measure, for they would all possess a different style of beauty, yet each would still be beautiful. The artist, therefore, who intends to excel in historic painting, should be conversant with all these. How much the ideas of the ancients varied respecting beauty, may be seen from con- sulting their works, which still remain to us. The Venus de Medicis, Niobe, Ariadne, and the Antinous, are matchless examples of beauty; yet how different are they ! The Apollo de Belvidere is majesty personified; and who could look at the head only of the Tarnesian Hercules, and not recognize strength as the leading feature of the whole statue? Costume, too, should occupy his attention—every part of his picture should harmonize. Even when designing stories from ancient times, the costume and manners of those times should be attended to ; for if the subject is worth painting, it is surely worth painting well and accurately. Nothing should be con- sidered unimportant which can iſlustrate the subject intended to be represented. It is not necessary for this purpose to crowd the design with a multitude of inferior objects or ornaments; but when such things are introduced, they should be in character. Simplicity of style partakes often of the sublime. To paint Cato in timselled robes and gewgaws would be indeed absurd, yet there are subjects in which it would be equally absurd to omit them. The intended artist must be aware, that before he can draw a whole figure, he must draw each feature and limb separately, and this is not to be slightly done, but from the best designs or models he can procure, with the greatest attention, till he is familiarized with every one of them. The hands and feet are particularly difficult, and require an infinity of practice: per- haps indeed perfection in the innumerable forms they take, is not to be acquired, except by those who study anatomical drawings. This is but little attended to by beginners, who are impatient to draw a “whole ienqth figure 1” foolishly imagining, that because they can make a heap of unmeaning eyes and * When the late Mr. West first saw the Apollo Belvidere, he exclaimed, - “How like a young Esquimaux Indian he looks l’” The Italians were offended, till he assured them “he had seen an Esquimaux precisely in the same attitude when eager in his chase.” West was an American by birth, noses, misshapen hands and feet, &c. they are fully competent to join them together, and having done so, they produce an ill- formed disgusting object, which in fact proves they are but “nature's journeymen who had made men, and not made them well, they imitated humanity so abominably.” This should be reformed altogether. Drawing is a work of infinite labour. Genius may shew itself early, and produce fine wild sketches, prophetic of what may be done in future, but genius alone without study, never can produce a perfect work; it may and will sooner acquire perfection, but no excellence beneath the sun is to be attained without labour. This cannot be too deeply impressed upon the learner’s mind. It would be advisable as one of the steps to freedom of drawing, to observe, that the pencil in sketching should be held at a greater distance from the point, than a pen in writing; and indeed longer than it is necessary to hold it in finishing. The hand, in sketching or drawing, should not rest on the ends of the two last fingers, as in writing ; but it should not, if the drawing is large, touch the paper at all in making the first outline, and the palm of the hand should turn upwards nearly ; in smaller drawings, not so much so, because it would be scarcely possible to steady the hand sufficiently to make minute touches without a support.t The artist should stand as much as possible at his studies, because standing is more generally conducive to health, than sitting and stooping over a desk for a continuation. The materials for drawing are, lead pencil and chalk. Indian rubber should be used as little as possible, for two reasons— in the first place, it soils the paper when too frequently applied to it; and in the second, it gives an idle incorrect style of drawing, which should be most carefully avoided. The first sketch should be so light, that the last correction, and it should undergo many, should conceal it wholly. Correct subjects to copy from, and fine models, are indispensable. With regard to the shading of figures without colour, two means are adopted; the one is accomplished thus: We give a round object, because it comprises light, shade, and reflection, decidedly. 1. Light. 2. Shade. 3. Reflection. If the eye be half closed, these three will be distinctly observed ſº-º-º: …T-> upon all round objects, whether long, É. as in a cylindrical form, or in a globe, # or on a woman’s arm, the roundness à of which is not interrupted by strong à muscular lines. Care should be taken, that the lines forming a shadow do not make Squares, thus, -but rather thus, - ==== E;- - - which lines harmonize, and do not offend the eye. Fores' drawing book gives excellent specimens of this shading, and the engravings are exact representations of what pencil and chalk shading should be, unless they are softened with a stunnp. The stump is principally applied to chalk drawing upon coloured paper. White chalk is then used to mark those prominent parts, which upon white paper would be left untouched. As the student advances in his studies, he will find pleasure increase, and it is very seldom that the diligent and skilful remain in obscurity, when they have attained to a certain degree of excellence ; but he should be content to be unknown till that period arrives. TXiligently and secretly he must work his way, till he feels he may venture before a judicious, discern- ing, enlightened public. With regard to Landscape Drawing, its foundation is per- spective, (see Perspective,) and its colouring must be drawn from nature, (see PAINTING...) In drawing Flowers, the learner should copy first of all front but still we should fancy an Iroquois, or Canadian Indian, nearer the model than an Esquimaux. + Artists frequently rest the arm on a piece of wood placed edgeways, when painting large pictures. 244 D R E D. R. O Diction ARY of MECHANICAL SCIENCE. a sprig of laurel leaves, as the most simple in their formation, and their size requiring great freedom in the use of the pencil. Indeed, it would be an advantage to practise for some time mere lines of this description, since a combination of them in Numerous have been the plans adopted by diſſerent artists to produce a brilliancy of effect in flowers. Some colours can only be procured by distillation; but in this the beginner must use his own powers of discrimination. Body colours for the leaves, have been frequently and strongly recommended, but body colour is not essentially and absolutely necessary, (of course we are speaking of water colours.) It is possible to produce the most accurate resemblance of nature by common water colours, but then this perfection must be attained by repeated attempts from nature; and flowers should be always placed in the sun when they are copied, because, as it is next to impossible ever to give the brilliancy of some ſlowers, (except in oil painting,) the stronger the light, and shade, and colour are in nature, at the moment the object is copied, the greater probability will there be that the drawing will be effective, than if deprived of these aids. White paint upon white flowers should be used sparingly; fine common chalk nicely pulverized with a little gum water, constitutes, perhaps, one of the best and most permanent white paints. Newman’s “Constant White” is, however, an excellent article, but the ordinary “flake whites,” &c. all turn black in time. . A perfect knowledge of colour can only be obtained by practice and the study of nature. Repetition day after day of the effect of the different colours when mixed, and the uses to which they may be applied, will give the rising artist that, which will in the end constitute an original and natural style of colouring. But, as it is supposed no beginner would pre- sume to decide against the opinion of those whose instructions he is receiving, the above remarks are not intended to set the pupil in opposition to his master, but merely to impress upon the mind of the student, that to an artist’s eye, every flower that blows, the largest or the smallest objects which surround him, whether a majestic tree or the smallest flower, whether a purl- ing stream, a foaming torrent, a stagnant pool, or even the minute drop of glistening dew which trembles on the morning rose, these, and millions of other objects, should be to him, not only sources of pleasure, but of intense attention and re- flection. Let him rise with the sun, and see how different the scene of a lovely landscape is, when the first rosy tints of morning ap- pear—let him watch the varying hues which succeed as the vapours disperse and the golden orb advances—let him ob- serve the stillness, the freshness of this season, and let him contrast it with the effects of a noon-day sun–then let him see the glorious orb sinking in golden purple floods of radiance. Still let him watch till the moon’s pale beams throw her silvery lustre over the same sweet landscape, and let him mark the different effect of the same objects, in the same summer day ! and view them again when the stormy clouds presage a tempest. Het him do this to the end of the chapter, and the youthful aspirant may, in time, become the renowned and celebrated artist. Whatever class of drawing or painting the artist chooses, Nature must still be his model, if he would attain perfection. DREAMS have been described as the imaginations, fancies, or reveries of a sleeping man, and they are said to be deducible from the three following causes: 1. The impressions and ideas lately received, and particularly those of the preceding day. 2. The state of the body, particularly the stomach and brain ; and, 3. Association. A Mr. Andrew Carmichael has started a very ingenious theory of dreaming. He enumerates no less than seven different states of sleeping and waking:—1. When the entire brain and nervous system are buried in sleep; then there is a total exemption from dreaming. 2. When some of the mental organs are awake, and all the senses are asleep : then dreams occur, and seem to be realities. 3. When the above condition exists, and the nerves of voluntary motion are also in a state of wakefulness; then may occur the rare pheno- menon of somnambulism. 4. When one of the senses is awake, with some of the mental organs; then we may be conscious, during our dream, of its illusory nature. 5. When some of the mental organs are asleep, and two or more senses awake; then we can attend to external impressions, and notice the gradual departure of our slumbers. 6. When we are totally awake, and in full possession of all our faculties and powers. 7. When under these circumstances we are so occupied with mental operations as not to attend to the impressions of external objects; and then our reverie deludes us like a dream. DREDGE, a kind of drag used with a long rope to catch oysters in deep water. - s DRESSING of OREs, the breaking and powdering them in the stamping-mill, and afterwards washing thern in a wooden trough. r - * * . . . . DRIFT, in Mining, a passage dug under the earth, betwixt shaft and shaft, or turn and turn; or a passage or way wrought under the earth, to the end of a meer of gröund, or part of a IIlê 6. I’. r - - * 4 DRIFT, the angle which the line of a ship's motion makes with the nearest meridian, when she drives with her side to the winds and waves, and is not governed by the power of the helm. It also implies the distance which the ship drives on that line. A ship's way is only called drift in a storm, and then when it blows so vehemently as to prevent her from carry- ing any sail, or at least restrain her to such a portion of sail as may be necessary to keep her sufficiently inclined to one side, that she, may not be dismasted by her violent labouring, produced by the turbulence of the sea. - DRILL, in Mechanics, a small instrument for making such . holes as cannot be done with punches. DRILL, or Drill-boa, a name given to an instrument for sow- ing land in the new method of horse-hoeing husbandry. Drill sowing is a method of sowing grain or seed of any kind, so that it may all be at a proper depth in the earth, which is necessary to its producing healthful and vigorous plants. For this pur- pose a variety of drill ploughs have been invented and recom- mended: but partly from the expense attending the purchase, partly from the complication of their structure, and partly from the attachment of the illiterate farmer to long habits, these schemes for diminishing labour have not received the encou- , ragement to which they are entitled, DRIVING, in the Sea-language, is said of a ship when an anchor being let fall will not hold her fast, nor prevent her sailing away with the tide or wind. 1)ROMEDARY, or ARA BIAN CAMEL, is distinguishable from every other species of camel by having a single bunch upon the middle of its back. This animal, which is a native of many of the deserts of Asia and Africa, is of a tawny gray colour, and has soft hair, which is longer on the neck, under the throat, and on the bunch, than elsewhere. The Arabian, like all other species of camel, has its upper lip cleft, and its feet with two long hoofs, on which it treads, and two others shorter, which do not touch the ground. These animals con- stitute the principal source of riches, and the whole force and security, of the Arabians. They are the only beasts by which the inhabitants of the sandy deserts of many parts of Asia could travel or convey their burdens. The caravans of merchants, which traverse in all directions the deserts of Egypt and Arabia, are accompanied by camels, that are often more in number than the men. These commercial travels are sometimes to the distance of 700 or 800 leagues, and are usually performed at the rate of ten or twelve leagues a day, the camels being every night unloaded to rest and feed. The burden of each came usually weighs about half a ton, and at the command of his conductor he kneels down, for the greater convenience of being loaded. The pace of the camel is a high and swinging trot, which to persons unaccustomed to it is at first disagreeable and apparently dangerous, but is afterwards suſliciently pleasant and secure. The Arabians in general ride on a saddle that is hollowed in the middle, and has at each bow a piece of wood placed upright, or sometimes horizontally, by which the rider |D P. () D R U. 245 DICTIONARY | OFM. MECHANICAL SCIENCE. keeps himself in the seat. A ring is inserted into the nostrils of the camel, to which a cord is affixed; and this serves as a bridle to guide and stop-him, or to make him kneel when the rider wishes to dismount. In the caravans of one of the Abys- sinian tribes, the people, armed with javelins, sometimes ride two together on each camel, and sit back to back. * . The camels of Sahara are probably more fleet than any that are known; and on these animals the Arabs, with their loins, breast, and ears bound round, to prevent the injurious effects of percussion from the quickness of motion, can cross that great desert in a few days. With a goat's skin or a porous earthen pitcher filled with water, a few dates, and some ground barley, the Arab travels from Timbuctoo to Morocco, feeding his camel but once upon the road. In one instance a camel was known to travel from Fort St. Joseph, on the river Sene- gal, to the house of Messrs. Cabane and Depras at Mogador, a distance of more than 1000 miles, in seven days. The hair, or fleece, of these animals, which is renewed every year, and which regularly falls off in the spring, is so soft, that the finest parts of it may be manufactured into stuffs of beauti- ful texture; and in Europe, when mixed with the fur of the beaver, it is sometimes made into hats. The inhabitants of some parts of Sahara live in tents of woven camel's hair, which forms a thick covering completely water-proof. After the hair has been stripped off, the skin is converted into leather. In Arabia, the milk of the camel is a most important article of nutriment; and the º though dry and hard, is not unpalat- able, particularly when young. By the inhabitants of Egypt this is so much esteemed, that, in Cairo and Alexandria, it was formerly forbidden to be sold to the Christians. In many parts of Africa the tongues are salted and dried, both for use and ex- portation; and with the ancient Romans the heels of camels were eaten as a great delicacy. - The Bactrian, or Two-bunched Camel, is known from the Arabian species by having two bunches on its back, by being somewhat larger, and having shorter legs. This animal is found in Usbec Tartary, the ancient Bactria: it is likewise a native of Siberia, Thibet, and some parts of China. The pur- poses to which the Bactrian camel are applied, are the same as those already described respecting the Arabian species. These animals, however, are sufficiently hardy to sustain the climate of the temperate parts of Siberia, and to be able, without in- jury, to traverse even humid and marshy countries, which would soon prove fatal to the Arabian camel. DRONE, in Music, the largest tube of the bagpipe; the office of which is to emit one continued deep note, as an accompanying bass to the air or tune played on the smaller pipes. DROPS, in Meteorology, small spherical bodies which the particles of fluids spontaneously form themselves into, when let fall from any height. This spherical figure, the Newtonian philosophers demonstrate to be the effect of corpuscular attraction. DROPSY, in Medicine, an unnatural collection of watery humours in any part of the body. - DROWNING, signifies the extinction of life by immersion in water. Various plans for the recovery of drowned persons have been given, but the most tried and approved is that of the Royal Humane Society, as follows: 1. When the patient is taken out of the water, the wet clothes should be taken off with all possible expedition on the spot (unless some convenient house is near,) and a great coat or two, or some blankets, wrapped round the body. 2. The patient is to be carefully conveyed in the arms of three or four men to the nearest house, where, if in the winter season, a good fire, and a warm bed, can be made ready for its reception. As the body is conveying to this place, great attention is to be paid to the position of the head; which must be kept supported in a natural and easy posture, and not suffered to hang down. - 3. In cold or moist weather, the patient is to be laid on a mattress or bed before the fire, but not too near, or in a mode- rately heated room; in warm and sultry weather, on a bed only. The body is then to be wrapped as expeditiously as possible with a blanket, and thoroughly dried with warm coarse cloths or flannels. 4. In summer or sultry weather, too much air cannot be admitted. For this reason it will be necessary to set open the windows and doors. . . 3. 5. Not more than six persons are to be present to apply the proper means; a greater number will be useless, and may pre- vent the restoration of life, by rendering the air of the apart- ment unwholesome. 6. It will be proper for one of the assistants; with a common pair of bellows, applying the pipe a little up one nostril, to blow with force, to introduce air into the lungs; at the same time the other mostril and the mouth are to be closed by another assistant, while a third person gently presses the chest with his hands, after the lungs are inflated. If the pipe of the bel- lows is too large, the air may be blown in at the mouth, the nostrils being closed, so that it may not escape that way. 7. Let the body be gently rubbed with flannels, sprinkled with spirits. A warming pan heated (the body being sur- rounded with flannel) may be lightly moved up and down the back. Fomentations of hot brandy are to be applied to the pit of the stomach, loins, &c., and often renewed. Bottles filled with hot water, heated tiles covered with flannel, or hot bricks, may be applied to the soles of the feet, palms of the hand, and other parts of the body. The temples may be rubbed with spirits of hartshorn, and the nostrils now and then tickled with a feather; and snuff, or eau-de-luce, should be occa- sionally applied. 8. Tobacco-fumes should be thrown up the fundament: if a fumigator is not at hand, a common pipe may answer the pur- pose. This operation should be frequently performed, for the good effects of this process have been experienced in a variety of instances. But should the application of tobacco-smoke in this way not be immediately convenient, or other impediments arise, clysters of this herb, or other acrid infusions with salt, &c., may be thrown up with advantage. 9. When these means have been employed a considerable time without success, and a brewhouse is near, or a warm bath can be readily obtained, the body should be carefully conveyed to such place, and remain in the bath, or surrounded with warm grains, for three or four hours. If a child has been drowned, its body should be wiped dry, and placed in bed between two healthy persons. The salutary effects of the natural warmth, conveyed in this manner, have been proved in a variety of cases. 10. While the various methods of treatment are employed, the body is to be shaken every ten minutes, to render the pro- cess of animation more successful ; and children are to be much agitated, by taking hold of their legs and arms frequently and for some time. . 11. If there are any signs of returning life, a spoonful of warm liquid may be given; and if the act of swallowing can be performed, a cordial of warm brandy or wine may be given in small quantities, and frequently repeated. 12. Electricity may be tried by the skilful, as its application neither prevents nor retards the various modes of recovery already recommended; but, on the other hand, it will most probably tend to render the other means employed more ex- peditiously efficacious. The methods which have been described, are to be employed with vigour for three hours or upwards, although no favourable circumstances should arise; for it is a dangerous error to sup- pose that persons are irrecoverable, because life does not soon make its appearance. Bleeding is never to be employed un- less by direction of a medical person. DRUG, a general term for goods of the druggist and gro- cery kinds, especially for those used in medicine and dyeing. DRUGGET, in Commerce, a stuff sometimes all wool, and sometimes half wool, half thread; it is either corded or plain. DRUIDS, the priests or ministers of religion of the ancient Britons and Gauls. The druids were chosen out of the best families; and were held, both by the honours of their birth and their office, in the greatest veneration. They are said to have understood astrology, geometry, natural history, politics, and geography: they had the administration of sacred things, were the expounders of religion, and the judges of civil affairs. DRUM, a martial musical instrument in form of a cylinder, hollow within, and covered at the two ends with vellum, which 3 R 246 D U C D U E DICTIONARY OF MECHANICAL SCIENCE. is stretched or slackened at pleasure by small cords and slid- ing knots. Some drums are made of brass, but they are com- monly of wood. Kettle drums are large basins of copperor brass, rounded in the bottom; and covered with vellum or goat-skin. DRY-ROT, a term or name applied to a rapid decay of any vegetable matter, when it has the appearance of being tolerably dry, but in general is applied only to timber when in that state, and is so named in contradistinction to the common mode of decay, by being exposed to the alternate states of wet and dry. There are a great number of causes for this species of decay: some are quite simple; others very complicated; yet whatever may be the original cause, simple or compound, the effects are the same, namely, to render the timber useless, by destroying its elasticity and toughness, rendering it insufficient to resist any considerable pressure, and, indeed, for any of the useful purposes to which timber is applied. When timber is in a tolerably dry state, any means which will absorb or extract its oxygen from the other component parts will leave it in the state commonly called dry rotten, Moist, warm situations, with little or no current of air, are the most likely to generate this evil. The effluvia from timber in such a state of decay will rapidly carry its effects to the circumjacent timber, however dry it may appear, and any sort of timber will be in a very little time ren- dered quite useless. When timber is exposed to any consider- able degree of moisture and heat, fungi of various shapes and texture, according to the species of timber, and other causes, will appear upon it; and although this fungous matter be really an effect of the dry-rot, yet it is as truly a cause of the same evil. There are no possible means of restoring rotten timber to a sound state, and the dry-rot can only be cured, as it is called, by removing the decayed and affected parts, clearing away all the fungi, and destroying its vegetating principle, with which the hard materials, such as bricks or stone, may have been impregnated. For this purpose, a strong solution of iron, copper, or zinc, is used with advantage. This, with the admission of a large quantity of air, is very advantageous. Many persons have written on the subject, and the nostrums proposed are as numerous as their authors. Timber once in- jured cannot be restored; but the evil may be stopped by removing the corrupted and contagious matter, and by the admission of a free circulation of air. Much also may be done by cutting timber in winter, and properly seasoning it by steep- ing it in water for some time, and then thoroughly drying it before it is used in building. . . . • º DUCAT, a coin current in Germany, and other countries abroad. In Germany, Italy, and Holland, it is of the value of about 9s. 3d. ; the ducat of Naples is 3s. 4d. ; that of Florence or Leghorn, 5s. 4d. ; the gold ducat of Portugal is £6. 15s. DUCATOON, a coinage in Holland and Flanders; in the former country its value is 5s. 6d. and in the latter 5s. 23d. DUCHY COURT, a court of the duchy-chamber of Lan- caster, held at Westminster before the chancellor of the same, for matters concerning the lands and franchises of that duchy. The proceedings in this court are by English bill, as in chan- cery. Gwyn says, that this court grew out of the grant of king Edward III. who gave the duchy to John of Gaunt, and endowed it with royal rights and privileges; several others of our ancient kings likewise separated this duchy from the crown, and settled it in the natural persons of themselves and their heirs; though, in succeeding times, it was united to the crown again. - - - DUCTILITY, the extensibility and cohesion of particles, which enables metal to be drawn into wire without breaking. There is but a shade of difference between this property and that of malleability. The ductility of some bodies, especially of gold, is very surprising: the gold-beaters and wire-drawers furnish us with abundant proofs of this property ; they every day reduce gold into lamellae inconceivably thin, yet without the least aperture or pore discoverable, even by the micro- scope; a single grain of gold may be stretched under, the ham- mer into a leaf that will cover a house, and yet the leaf remain so compact as not to transmit the rays of light, nor even admit spirit of wine to transude. But M. Reaumur has carried the ductility of gold to a still greater extent. What is called gold-wire, every body knows, is only a silver one gilt. The cylinder of silver, covered with leaf gold, they draw through the hole of an iron, and the gilding still keeps pace with the wire, stretch it to what length they can. Now M. Reaumur shews, that in the common way | of drawing gold wire, a cylinder of silver twenty-two inches long, and fifteen lines in diameter, is stretched to 1,163,520 feet, or is 634,692 lines longer than before, which amounts to about ninety-seven leagues. To wind this thread on silk for use, they first flatten it, in doing which it stretches at least one-seventh farther, so that the twenty-two inches are now 111 leagues; but in the flattening, instead of one-seventh, they could stretch it one-fourth, which would bring it to 120 leagues. This appears a prodigious extension, and yet it is nothing to what this gentleman has proved gold to be capable of. - DUCTILITY of Glass. We all know, that when penetrated with the heat of the fire, the workmen can figure and manage glass like soft wax ; but what is more remarkable, it may be drawn, or spun out, into threads exceedingly long and fine. Our ordinary spinners do not form their threads of silk, flax, or, the like, with half the ease and expedition the glass-spinners do threads of this brittle matter. We have some of them used in plumes for children's heads, and divers other works, much finer than any hair, and which bend and wave like hair with every wind. Nothing is more simple and easy than the method of making them. There are two workmen employed; the first holds one end of a piece of glass over the flame of a lamp, and when the heat has softened it, a second operator applies a glass hook to the metal thus in fusion; and withdrawing the hook again, it brings with it a thread of glass, which still adheres to the mass; then fitting his hook on the circumference of a wheel about two feet and a half in diameter, he turns the wheel as fast as he pleases, which drawing out the thread, winds it on its rim, till, after a certain number of revolutions, it is covered with a skein of glass-thread. The mass in fusion over the lamp diminishes insensibly, being wound out like a clue of silk upon the wheel ; and the parts, as they recede from the flame, cooling, become more coherent to those next to them, and this by degrees: the parts nearest the fire are always the least coherent, and of consequence, must give way to the effort the rest make to draw them towards the wheel. The circum- ference of these threads is usually a flat oval, being three or four times as broad as thicſ&; some of them seem scarcely big- ger than the thread of a silk-worm, and are surprisingly flexible. If the two ends of such threads are knotted together, they may be drawn and bent till the aperture, or space in the middle of the k does not exceed one-fourth of a line, or one-forty- eighth of aniach; in diameter: THence the flexibility of glass increases in proportion to the fineness of the threads; and probably, had we but the art of drawing threads as fine as a spider's web, we might weave stuffs and—cloths of them for wear, but could never make them long enough to be serviceable. See DivisiBILITY. ** DUEL, a single combat, at a time and place appointed; in consequence of a challenge. This custom came originally from the northern nations. Both the accuser and the accused gave pledges to the judges on their respective behalf; and the custom prevailed that none were excused from it but women, sick people, cripples, and such as were under 21 years of age, or above 60. Even ecclesiastics, priests, and monks, were obliged to find champions to fight in their stead. The punish- ment of the vanquished was either death by hanging or behead- ing; or mutilation of members, according to the circumstances of the case. Ouels were at first admitted, not only on criminal occasions, but on some civil ones, for the maintenance of rights to estates, and before the like : in later times, however, they were almost entirely abolished, being restrained to these four cases: 1. That the crime should be capital. 2. That it should be certain the crime was perpetrated. 3. The accused must, by common fame, be supposed guilty. And, 4. The matter not capable of proof by witnesses. But this also has been abolished, and there no longer exists the “trial by battle.” DUel, at present is used for a single combat on some private quarrel, and must be premeditated, otherwise it is called a rencounter. If a person be killed in a duel, both the principals and seconds are guilty of murder, whether the seconds engage or not. It is also a very high offence to challenge a person either by word or letter, or to be the messenger of a challenge. 3D U O D Y E 247 DICTIONARY OF MECHANICAL SCIENCE. DUET, in Music, a composition written for two voices or instruments, with or without a bass and accompaniments. DUKE, is either the title of a sovereign prince, as the Duke sof Modena, the Grand Duke of Tuscany, &c. or it is the title of honour and mobility next below princes. , Duke, at present in Britain, is a mere title of dignity, without giving any domain, territory, or jurisdiction, over the place from whence the title is taken. A duke is created by patent, cincture of sword, mantle of state, imposition of a cap and coronet of gold on his bead, and a verge of gold put into his hand. His title is, Grace; and, in the style of the heralds, Most high, potent, high-born, and noble prince. * - DULCIMER, a musical instrument, strung with about fifty wires cast over a bridge at each end. It is performed upon by striking the wires with little iron rods. - DUMBNESS, the privation of speech, the most general cause of which is the want of the sense of hearing ; language being originally acquired by imitating sounds. From this source of intelligence deaf people are entirely excluded; they 4:annot acquire articulate sounds by the ear: unless therefore articulation be communicated by some other medium, they must be deprived of language. Of late years it has been shewn, that though deaf people cannot learn to speak or read by the direction of the ear, there are other sources of imitation, by which the same effect may be produced. The organs of hearing and speech have little connexion. Persons deprived of the former generally possess the latter in such perfection, that nothing further is necessary to make them articulate, than to teach them how to use these organs. This, indeed, is no easy task, but it is practicable. The first thing is, to teach the pupil to pronounce the simple sounds of the vowels and con- sonants. The teacher pronounces the sound of the letter a very slowly, pointing to the figure of it upon paper at the same time, and makes the pupil observe the motion of his mouth and throat. He then puts his finger into his pupil’s mouth, depresses or elevates the tongue, and makes him keep the parts in that position; then he lays hold of the outside of the throat, and applies such a kind of pressure as shall indicate to the pupil a certain necessary action to be performed by the muscles. All the while he is pronouncing a, the pupil is anxiously imitating him, but at first seems not to understand what he would have him to do. In this manner he proceeds, till the pupil has learned to pronounce the sounds of the letters. He goes on in the same manner to join a vowel and a consonant, till at length the pupil is enabled both to speak and to read. DUODECIMALS, or CRoss MULTIPLic AtroN, (from duo- dicem, twelve,) is a rule used by workmen and artificers in com- puting the content of their work; dimensions are usually taken in feet, inches, and parts; but of the last, all those less than + of inches are frequently omitted as of little or no consequence, and the same is always done in casting up the contents, where they are of still less importance.—Rule. Set down the two dimensions to be multiplied together under each other, so that feet may stand under feet, inches under inches, and parts under parts. Then multiply each term in the multiplicand, beginning at the lowest, by the feet in the multiplier, and set the result of each directly under its corresponding term, observing to carry I for every 12, from the parts to the inches, and from the inches to the feet. In like manner, multiply all the multiplicand by the inches and parts of the multiplier, and set the result of each, one remove to the right-hand of those in the multiplicand, and the sum of these successive products will be the answer. Or, instead of multiplying by the inches and parts, such parts of the multiplicand may be taken as fbese are of a foot. Examples. Miultiply 6 feet, 4 inches, 3 parts, by 10 feet, 3 inches, 9 parts. - Otherwise : ft. in. 1. - ft. in. p. 6 4 3 3 in. = }| 6 4 3 10 3 9 “ – lº. . ; 63 6 6 63 6 6 i 1 7 0 9 9 p. = }| 1 7 03 4 9 2 3 T *| 4 g. - Tö feet 65 6 3 answer. feet 65 6 33 It may not be amiss to observe here, that the feet in the answer are square feet, but the numbers standing in the place of inches are not square inches, as one might at first inſer, but 12th parts of square feet, each part being equal to 12 square inches. . In like manner, the numbers standing in the third place, or place of parts, are so many 12th parts of the preced- ing denomination, these therefore are square inches; and in the same manner, if the operation be carried farther, every suc- cessive place will be a 12th part of that preceding it. - DUODECIMO, is used to denote the size of a book when the sheets are folded into twelve leaves. . . s DUODECUPLE, consisting of twelves. - DUODENARY ARITH Metic, is that in which the local value of the figures increases in a twelvefold proportion from right to left, instead of the tenfold proportion in the common or denary arithmetic. Thus llll, in the duodenary scale, expresses 12" -- 12 + 12 + 1 = 1885 in the common scale. Every number may be converted from one scale to the other, and in many cases the duodenary system (particularly after practice has rendered it familiar) possesses considerable advantages over that in common use. In the duodenary scale of notation, there must be introduced two new characters for expressing 10 and 11, and these may be represented by q and ºr, that is 10 = p ; 11 = tr; so that the digits of this system become 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, p, ar, with which characters any number whatever may be expressed according to the duodenary system, the same as in common arithmetic, by the nine simple digits. * * DUPLE, among Mathematicians, denotes the ratio of 2 to 1. Thus the ratio of 8 to 4 is duple, or as 2 to 1. Sub-DUP Le Ratio is just the reverse of the former, or as 1 to 2. - . DUPLICATE, among Lawyers, denotes a copy of any deed, writing, or account. It is also used for a second letter written and sent to the same party and purpose as a former. DUPLICATE Proportion, is a compound of two ratios; thus, the duplicate ratio of a to b, is the ratio of a a to b b, or of the square of a to the square of b. - . . . . t DUPLICATION, in general, signifies the doubling of any thing or multiplying of it by 2; also the folding of any thing back again on itself. - - DURATE, in Music, a term properly applicable to whatever offends the ear by its effect. . - . . DURESS, in Law, is where a man is kept in prison, or restrained of his liberty, contrary to the order of the law. DUTY, in Policy and Commerce, signifies the impost laid on merchandises, at importation or exportation, commonly called the duties of customs; also the taxes of excise, Stamp- duties, &c. DYE, in Architecture, any square body, as the trunk, or notched part of a pedestal ; also a cube of stone placed under the feet of a statue, and over its pedestal. - DYEING OF CLoTHS, is the art of tingeing cloth, or other matter, with a permanent colour, by penetrating its sub- stance, and imparting different colours to wool, silk, linen, &c. The substances employed are called colouring matters or dye- stuffs, and are extracted from animal and vegetable substances. If the colouring matters were merely spread over the surface of the fibres of cloth, the colours produced might be bright, but they could not be permanent; because the colouring matter would disappear whenever the cloth was washed or exposed to the weather. The colouring matter cannot seize upon the cloth permanently, unless there be an affinity between them. And since there can be no aſſinity till the dye-stuffs have been reduced to their integrant particles, dyeing is a process purely chemical. The colouring matter is first dissolved in some 5 liquid Which has a weaker affinity for it than the cloth has. , When the cloth is dipped in this solution, the colouring matter is brought within the attracting distance; the cloth acts upon it, and, from its stronger affinity, takes it from the mordant and fixes it upon itself . The equality of the colour is also secured by this contrivance, as every part of the cloth has an oppor- tunity of attracting to itself the proper proportion of colouring particles. Wool has the strongest aſſinity for almost all colour. ing matters; the next strongest is cotton, which has a con- siderably weaker affinity, and linen the weakest of all. In order therefore to dye cotton or linen, the dye-stuffs should be 248 D Y E D. Y. E DICTIONARY OF MECHANICAL SCIENCE. dissolved in a substance for which it has a weaker affinity than for the solvent employed in the dyeing of wool or silk. To dye wool, we use oxyde of iron; to dye cotton or linen, acetous acids answer best. * - Of Mordants. To render dyeing colours permanent, a mor- dant is pitched upon, which has a powerful attachment to both the cloth and the colouring matter. The mordant is previously combined with the cloth, which is then plunged into the solu- tion of dye-stuff, and the dye-stuff combines with the mordant, which being firmly combined with the cloth, secures the per- manency of the dye. The proper preparation and the appli- cation of mordants are the principal considerations in the art of dyeing. The mordants must be previously dissolved in some liquid which has a weaker affinity for them than the cloth has to which they are to be applied; and the cloth, to saturate itself with the mordant, must be dipped or steeped in the solution. The mordants are earths, metallic oxydes, tam, and oil. Alumine, the most important mordant earth that dyers use, is indispensable to dyers and calico printers, not only on account of its cleansing and opening the pores of the sub- stances to be dyed, and thus rendering them fit to receive the colouring particles, but also from its more essential property of fixing the colours, or that they cannot afterwards be washed out. Alumine is used either in the state of common alum or in that of acetite of alumine. Lime is also used as a mordant, either as lime water, or sul- phate of lime dissolved in water. The metallic oxydes of tin and iron are the most generally used; the former gives brightness to reds and scarlets, and precipitates the colouring matter in other dyes; the latter has a strong affinity for all kinds of cloth, as is proved abundantly by the difficulty we have to remove iron spots (moulds) from linen or cotton cloth. And as a mordant it is used either as sulphate of iron or acetite of iron. - Tan and Oil. On the leaves and buds of the oak certain excrescences are formed, in consequence of the puncture of insects, as a lodgment for their eggs and a habitation for their future young. These are termed galls, and if, when arrived at a certain state, they are infused in a weak solution of vitriol, they impart to it a purple or violet tinge; and after the whole colouring matter is extracted, this, becomes perfectly black. Considerable quantities of galls are used in dyeing, and for other purposes. Tan adds to the weight of silk, and is there- fore much used; oil is also used for the same purpose. Besides these, tartar, acetite of lead, common salt, sal ammoniac, sulphate or acetite of copper, are used as mordants, which not only render the dye permanent, but have also considerable influence on the colour produced. The same colouring matter produces very different dyes, according as the mordant is changed. Sup- pose, for instance, that the colouring matter be cochineal; if . we use the aluminous mordant, the cloth will acquire a crim- son colour; but the oxyde of iron produces with it a black. In dyeing, then, it is not only necessary to procure a mordant which has a sufficiently strong affinity for the colouring matter and the cloth, and a colouring matter which possesses a wished for colour in perfection, but we must procure a mordant and a colouring matter of such a nature, that, when combined together, they shall possess the wished-for colour in perfection. It is evident too, that a great variety of colours may be produced with a single dye-stuff, provided we can change the mordant sufficiently. The colouring matter with which the cloth is dyed, does not cover every portion of its surface : its particles attach themselves to the cloth at certain distances from each other; for cloth may be dyed different shades of the same colour, lighter or darker, merely by varying the quantity of colouring matter. With a small quantity, the shade is light; and it be- comes deeper as the quantity increases; now, this would be impossible, if the dye-stuff covered the whole of the cloth. That the particles of colouring matter, even when the shade is deep, are at some distance, is evident from this well-known fact, that cloth may be dyed two colours at the same time. All those colours to which the dyers give the name of compound, are in fact two different colours applied to the cloth at once. Thus cloth gets a green colour, by being first dyed blue and then yellow. The colours denominated by dyers, simple, because they are the foundation of all their other processes, are four; namely, blue, yellow, red, and black. To these they usually add a fifth, under the name of root, or brown colour. To dye Blue. The substances principally used in this dye, are indigo and woad, with which every kind of cloth may be dyed without a mordant. Indigo is brought from the West Indies. It is drawn from the leaves of a plant called anil. Woad is obtained from the leaves of a plant, which, when ripe, are gathered and suffered to lie some time, and then put under the wheel to be bruised or ground; after this they are laid eight or ten days in piles or heaps; and at last made up into balls, which are laid in the shade, on hurdles, to dry. The balls are then pulverized, spread upon the ground, and watered: it smokes and heats till it becomes dry; it is then fit for use. The ancient Britons dyed their bodies with this substance. Woad-blue is a very deep blue, almost black; and is the base of so many sorts of colours, that the dyers have a scale by which they compose the different casts, or degrees of woad. Process. When wool, cotton, or silk is intended to be dyed, the cloth is first wetted with hot water and wrung out; then it is immersed in a clear dye-liquor, and remains therein accord- ing to the shade wished for; it comes out green, but soon turns blue on being exposed to the air. Cotton intended to be dyed blue is first passed through water containing sulphuric acid. Silk is dyed a light blue by a ferment of six parts of bran, six of indigo, six of potash, and one of madder. But cotton and linen are dyed blue by a solution of one part of indigo, one of green sulphate, and two parts of quick-lime. Mr. Richard Badnall, of Leck, in Staffordshire, silk manu- facturer, has taken out a patent for improvements in the appli- cation of Prussian blue to the purposes of dyeing silk, cotton, wool, or any other article; and, in the application of pressure to dyeing in general. The Prussian blue being previously ground as fine as pos- sible, is put into any convenient vessel of glass or earthenware. Strong muriatic acid is to be poured upon it a little at a time ; and the mass is to be kept constantly stirred, with a rod of white wood, a piece of tobacco pipe, or any other material not liable to be acted upon by the acid. The stirring must be con- tinued till the mixture has become a smooth homogeneous mass of a semi-gelatinous consistence. The proportion of acid re- quisite for this purpose depends, in some degree, on the quality of the Prussian blue, and, therefore, cannot be precisely set forth in words; but, by proceeding carefully, as above de- scribed, it is impossible to fall into error; as the mixture, if made too thin from excess of acid, may be rectified by the sub- sequent addition of more Prussian blue. This mixture may be used as soon as made; but it is better after three or four days, and its qualities are not altered by age. In dyeing silk with the Prussian blue, prepared as above, Mr. B. proceeds in the following manner: “The gum having been discharged from the silk by any of the usual means, the silk is steeped, for three or four hours, in a cold solution of alum in water, of the common strength em- ployed by silk dyers; and then rinsed in cold water. “The dye vat is composed by diluting the prepared Prussian blue with cold water, till its colour is of the required depth, according to the particular tint intended to be given to the silk. The silk, prepared as above, is them to be put on sticks, and immersed in the bath, taking care that it be constantly turned, that the colour may be perfectly level, and that it remain in the bath till it has acquired the proper tint or shade. It is then to be well washed in running water till it ceases to be dis- coloured by it. Lastly, the silk is to be dried, either in the shade, or in a stove heated to not more than summer temperature. “From Prussian blue, prepared as above, various greens and purples may be obtained; either by combining it with the in- gredients usually employed for such colours, and dipping the silk in this compound bath; or, by using the bath of prepared Prussian blue, either before, or after the application of the other ingredients, according to circumstances, and to the nature of such ingredients. The proportion, however, it is not necessary to recite: the object of this part of the patent being merely by a new mode of preparing Prussian blue, to dye silk, cotton, wool, or any other article, either alone, or mixed and combined with other dyeing materials. - D Y E D Y E 249 DICTIONARY OF MECHANICAL SCIENCE. “The second invention is the application of pressure to dye- ing in general, whether it be that of thick cloths, hats, woods for veneering, or any other purpose; or any other or more deli- cate materials, such as linen, cotton, or silk goods, lace, &c. For this purpose, the materials to be dyed are to be placed, with the dyeing liquor, in any suitable vessel of wood, copper, iron, or other material; the aperture of which vessel can be secured water-tight, by a lid fitted to it by any suitable and well-known means. To this vessel is to be fitted a hydrostatic pressure-pump, (as Bramah's, for example,) or any other ma- chinery employed for the purpose of producing high pressure ; such as a column of water or mèrcury of sufficient height, &c. All things being thus adjusted, the lid is to be fitted securely on, and the pump worked, until the uecessary pressure is ob- tained; when it is evident, that if the goods are put in dry, or well wrung, the pressure thus produced will greatly facilitate the introduction of the dyeing liquor within the internal pores, particularly in heavy cloth goods, hats, woods, hard twisted silk, or lace; and, if necessary, suitable mechanical means may be employed to agitate, and wring the goods while under pressure: but this is not claimed exclusively, but only the application of pressure to the forcing of the dyeing liquor into the pores of the cloths, hats, silk, woods, &c.; or the joint application of pressure, with suitable means for producing agitation, &c. &c.” * * To dye Red. The process of dyeing red requires a peculiar preparation of the stuffs, on the exactness of which the good- ness and permanency of the colour depend. These preparatory ingredients consist of alum, tartar, nitric acid, or a solution of tin in nitric acid. Galls and alkaline salts are also sometimes added. The Carthamus Tinctorius plant, a native of Egypt and the Levant, gives a poppy, cherry and rose-red, and flesh colour to silk, and is also employed in making rouge. This last is made by precipitating with lemon juice the red colour- ing matter extracted by carbonate of soda. Madder is the root of a plant called rubia tinctorium. Alum and tartar are em- ployed in the preparation of the ingredients for this red. Cochi- meal consists of an insect which is collected round the Indians fig-tree, and is found abundant in South America. Kermes, an insect about the size of a juniper berry, round, smooth, and glossy, is of a beautiful red colour, and full of a juice of the same dye. It is found adhering to the bark, on the stem and the branches of a small oak, growing in Spain, Languedoc, and other countries. This colour is the most permanent, but the least bright; it is apt also to be less spotted than the others; but, on account of the difficulty of procuring the insects which afford the colour, it is very seldom used in Britain. Logwood and Brazil-wood are also used for red dyes, but the colour is not durable. The latter grows in the warmest parts of South America. Logwood is found in the Bay of Campeachy. Alcohol best extracts the colouring matter of the logwood. Of dyeing Yellow. The principal colouring matters for dye- ing yellow are weld, fustic, and quercitron bark. Weld is a plant, which grows wild in barren and uncultivated places, par- ticularly on coal-pit banks, in several parts of England. Fustic is the wood of a large tree which grows in the West Indies. Quercitron is a tree growing naturally in North America, the bark of which contains colouring matter. Yellow colouring matters have too weak an affinity for cloth, to produce per- manent colours without the use of mordants. Cloth, therefore, before it be dyed yellow, is always prepared by combining some mordant or other with it, as alumine or oxyde of tin, Tan is often employed as a subsidiary to alumine, and in order to fix it more copiously on cotton and linen. Tartar is also used to brighten the colour; and muriate of soda, sulphate of lime, and even sulphate of iron, to render the shade deeper. The yellow dyed by means of fustic is more permanent, but not so beautiful as that by weld or quercitron. As it is permanent, and not much injured by acids, it is used in dyeing compound colours, where yellow is required. The mordant is alumine. When the mordant is oxyde of iron, fustic dyes a permanent drab colour. Weld and quercitron bark yield nearly the same colour; but as the bark yields colouring matter in much greater abundance, it is more convenient, and cheaper than weld. The method of using each of the dye-stuffs is nearly the same. To dye Wool Yellow. Boil the wool for an hour with about 27. one-sixth of its weight of alum, dissolved in water. Then plunge it, without being rinsed, into a bath of warm water, containing as much quercitron bark as equals the weight of the alum employed as a mordant. The cloth is now turned through the 'boiling liquid, till it has acquired the intended colour. Then a quantity of clean powdered chalk, equal to rim part of the weight of the cloth, is stirred im, and the operation of dye- ing continued for eight or ten minutes longer. By this method a pretty deep and lively yellow may be given fully as perma- nent as weld yellow. For very bright orange yellow, it is necessary to have recourse to the oxyde of tin as a mordant; and to produce bright golden yellows, some alum must be added along with the tin. But to give the yellow a delicate green shade much admired, tartar must be added in different proportions, according to the shade. And by adding a small proportion of cochineal, the colour may be raised to a fine Orange, or even an aurora. - Silk may be dyed different shades of yellow, either by weld or quercitron bark, but the last is the cheapest of the two. The proportion should be from one to two parts of bark to twelve parts of silk, according to the shade. The bark, tied up in a bag, should be put into the dyeing vessel, while the water which it contains is cold; and when it has acquired the heat of about 100 degrees, the silk, having been previously alumed, should be dipped in, and continued till it assumes the wished- for colour. When the shade is required to be deep, a little chalk or pearl-ash should be added towards the end of the operation. . Cotton and Linen are dyed yellow, thus: the mordant acetite of alumine is prepared by dissolving one part of acetite of lead, and three parts of alum, in a sufficient quantity of water. In this solution, heated to the temperature of 100 degrees, the cloth is soaked for two hours, then wrung out and dried. The soaking may be repeated, and the cloth again dried as before. It is then to be barely wetted with lime water, and afterwards dried. The soaking in the acetite of alumine may be again re- peated, and if the shade of yellow is required to be very bright , and durable, the alternate wetting with lime water and soak ing in the mordant may be repeated three or four times. By this contrivance, a suſficient quantity of alumine is combined with the cloth, and the combination is rendered permanent by . the addition of lime. The dyeing bath is prepared by putting 12 or 18 parts of quercitron bark (according to the depth of the shade required) tied up in a bag, into a sufficient quantity of cold water. Into this bath the cloth is put, and turned round in it for an hour, while its temperature is gradually raised to 120 degrees; it must be then brought to a boiling heat, and after that, the cloth allowed to remain in it only a few minutes. If it be kept long at a boiling heat, the yellow acquires a brown shade. Nankeen yellow is obtained by a solution of the red sulphate of iron, which is combined with the cloth by carbonate of potash. - To dye Fawn Colour. The process of dyeing this, colour differs from others, the wool merely requiring a simple immer- sion in water. Various substances are used for dyeing brown or fawn colour. 1. The bark or rind of the walnut-tree. Its shades are uncommonly fine; its colours solid; and it renders the wool flexible and soft. A cauldron half full of water is placed over the fire ; as soon as it grows warm, bark is added in proportion to the quantity of stuffs intended to be dyed, and the lightness or depth of the shades required. It is then boiled for a quarter of an hour, when the cloths, previously moistened with warm water, are immersed, frequently turned, and well stirred, till they have sufficiently imbibed the colour. They are then dried and dressed in the usual manner. The root of the walnut-tree is also employed, but with a different process. When the green walnut-shells are used, they are collected when the nuts are ripe; and are put into casks, which are afterwards filled with water, and thus preserved till the succeeding year. The bark of the alder-tree is chiefly used for worsted, impart- ing shades darkened with copperas. It is also used for wool that is not required to be very dark, as it equally withstands the effects of the sun and rain.” Sanders-wood is much inferior to walnut-shells; stiffens, and consequently injures the wool. . It is in general mixed with galls, sumach, and alder-bark, with- out which its colour could not be extracted. Sumach, where 3 S 250 D Y E D Y T DICTIONARY OF MECHANICAL SCIENCE. dark colours are required, is frequently substituted for nut- galls, in which case a greater proportion becomes necessary. These different substances, however, are not unfrequently mixed together; they are of a similar nature, differing only in a degree of colour, and it is easy to obtain various shades. It is both solid and permanent. Soot is only used when the other ingredients cannot be procured. . It is not only less solid than the others, but also hardens, and imparts a very disagreeable smell to the wool or stuff. - To dye Cloth Black. Red oxyde of iron and tan are employ- ed; log is used as an auxiliary, because it communicates lus- tre, and adds to the fulness of the black. Cloth, before it re- ceives a black colour, is dyed blue; but if the cloth be coarse, the blue dye is expensive ; in that case walnut-peels are used to give it a brown colour. PPool is boiled for two hours in a decoction of nut-galls, then kept two hours more in a bath of logwood and sulphate of iron, at a scalding heat, but not boiled. It must be frequently exposed to the air during the process, to imbibe oxygen before the cloth can acquire a pro- per colour. Silk is dyed nearly in the same manner, but as it is capable of combining with a great deal of tan, the quantity given is varied at the pleasure of the artist, by allowing the silk to remain a longer or shorter time in the decoction. Linen and Cotton previously dyed blue, are steeped for twenty-four hours in a decoction of nut-galls, mixed with a decoction of alder-bark. A bath is prepared, containing an acetite of iron. Into this bath the cloth is put in small quantities at a time, wrought with the hand for a quarter of an hour, wrung out, and aired again; then wrought in a fresh quantity of the bath, and afterwards aired. These processes are repeated till the requisite colour has been given to the cloth. Of dyeing Compound Colours, which are produced by mixing two simple colours together; or, by dyeing cloth first one sim- ple colour, and then another. These colours vary to infinity, according to the proportions of the ingredients employed, and may be arranged under the following classes. Mixtures of, 1. Blue and yellow. 2. Blue and red. 3. Yellow and red. 4. Black and other colours. - Mixtures of blue and yellow form green, which is distinguished by dyers into a variety of shades, according to the depth of the shade, or the prevalence of either of the component parts. Thus we have sea-green, grass-green, pea-green, &c. Wool, silk, and linen, are usually dyed green, by giving them first a blue colour, and afterwards dyeing them yellow; because, when the yellow is first given, several inconveniences follow: the yellow partly separates again in the blue vat, and communicates a green colour to it, and thus renders it useless for every other purpose, except dyeing green. Any of the usual processes for dyeing blue and yellow may be followed, taking care to pro- portion the depth of the shades to that of the green required. When sulphate of indigo is employed, it is usual to mix all the ingredients together, and to dye the cloth at once ; this pro- duces what is known by the name of Saxon or English green. Mixtures of blue and red form different shades of violet, pur- ple, and lilae. Wool is generally first dyed blue, and after- wards scarlet, in the usual manner. If cochineal be mixed with sulphate of indigo, the process may be performed at once. Silk is first dyed crimson by means of cochineal, and then dipped into the indigo wat. Cotton and linen are first dyed blue, then galled, and soaked in a decoction of logwood; but a more permanent colour is given by the oxyde of iron. - Mixtures of yellow and red produce orange. When blue is combined with red and yellow on cloth, the resulting colour is olive. Wool may be dyed orange, by first dyeing it scarlet, and then yellow. When it is dyed first with madder, the result is cinnamon colour. Silk is dyed orange by means of carthamus; a cinnamon colour by logwood, Brazil-wood, and fustic mixed together. Cotton and linen receive a cinnamon colour by means of weld and madder; and an olive colour, by being passed through a blue, yellow, and then a madder bath. Mixtures of black with other colours, constitute grays, drabs, and browns. If cloth be previously combined with brown oxyde of iron, and afterwards dyed yellow with quercitron bark, the result will be a drab of different shades, according to the proportion of mordant employed. When the proportion is small, the colour inclines to olive or yellow.; on the contrary, the drab may be deepened or saddened, as the dyers term it, by mixing a little sumach with the bark. DYKES. That the surface of the earth has been fractured since its consolidation, is proved by the appearances which rocks and strata in many situations present. It is further proved by the existence of vertical seams intersecting them, and filled with mineral matter of a different kind. When the substance found in these vertical seams is stone or earth, and they are of considerable thickness, they are called dykes or faults. When filled with metallic ores, they are generally called veins. t * DYNAMICS, is the science of moving powers, or of the action of forces on solid bodies, when the result of that action is motion. Mechanics, in its most extensive meaning, is the science which treats of quantity, of extension, and of motion. Now that branch of it which considers the state of solids at rest, such as their equilibrium, their weight, pressure, &c. is called Statics; and that which treats of their motion, Dynamics. So when fluids, instead of solids, are the subjects of investiga- tion, that branch which treats of their equilibrium, pressure, &c. is called Hydrostatics, and that which treats of their motion, Hydrodynamics. DYSENTERY, in Medicine, a flux or flatulency of the bowels, occasioned by stoppage of perspiration, especially in hot weather, unwholesome food, damp clothes, &c. The most proper treatment is by taking a gentle vomit, followed by rhubarb, or ten drachms of Glauber’s salts. DYSPEPSY, a difficulty of digestion, for which physicians prescribe bitters. - DYSPNCEA, a diſficulty of breathing, usually called asthma. DYTISCUS, the Water Beetle, in Zöology, a genus of insects of the order coleoptera, of which there are 23 species. E. E. A. R. E, the fifth letter in the alphabet, as a numeral, stands for 250. In Music, it denotes the tone e-la-mi. it is the fifth of the dominical letters. distinguishes all the easterly points. EAR, AURIs, in Anatomy, the organ of hearing. BARINGS, are certain small ropes employed to fasten the upper corners of a sail to its respective yard, for which purpose one end of the earing is spliced to the cringle fixed in that part of the sail, and the other end is passed five or six times round the yard-arm and through the cringle ; the two first turns, which are intended to stretch the head of the sail tight along the yard, are passed beyond the lift and rigging on the yard-arm, and are called outer turns, while the rest which draw it close up to the In the Calendar, And in Sea-charts, it E A. R. yard, and are passed within the lift, &c. are called inner turns. N. B. Every reef on a yard has its respective earings, which are passed in the same manner. . EARL, a British title of nobility, next below a marquis, and above a viscount. Earls were anciently called comites, because they were wont to wait upon the king for counsel and advice. The Germans call them graves, as landgrave, margrave, pals- grave, rheingrave; the Saxons, ealdermen; the Danes, eorlas; and the English, earls. The title, originally, died with the man. William the Conqueror first made it hereditary, giving it in fee to his nobles, and allotting them for the support of their state the third penny out of the sheriff’s court, issuing out of all pleas of the shire whence they had their title. - E. A. R. E. A. R. 251 DICTIONARY OF MECHANICAL SCIENCE. BAR.L. MARsh AL of ENGLAND, a great officer who had anciently several courts under his jurisdiction, as the court of chivalry and the court of honour. Under him is also the inerald's office, or college of arms. He has some pre-eminence in the court of Marshalsea, where he may sit in judgment against those who offend within the verge of the king’s court. BARNEST, a part of the price paid in advance to bind par- ties to the performance of a verbal agreement. The party is then obliged to abide by his bargain, and is not discharged upon forfeiting his earnest, but may be sued for the whole money stipulated, and damages; no contract for sale of goods not to be delivered immediately, to the value of £10 or more, is valid, unless contract is made by the parties, or those lawfully authorized by them, or earnest is given. - EARTH, in Astronomy and Geography, one of the primary planets, being this terraqueous globe which we inhabit. See AstroNoMY. EARTHQUAKE, a tremor or shaking of the earth, fre- quently accompanied with dreadful noises underground, or in the atmosphere, often destroying towns and cities, throwing down rocks, levelling hills, changing the course of rivers, &c. The most remarkable earthquakes recorded in history are, that of Herculaneum, by which that city was wholly destroyed, A. D. 79. The destruction of Nicomedia, Caesarea, and Mica, in Bithynia, A. D. 126. A dreadful one in Syria, by which about five hundred cities were destroyed or damaged in 745. Catania, in Sicily, destroyed, and 15,000 perished in the ruins, 1173. Port Royal, in Jamaica, with 3000 inhabitants, over- whelmed in 1692. Messina, in Sicily, destroyed, and above 18,000 persons killed, 1693. Lima and Callao, in South Ame- rica, destroyed, and 20,000 persons, 1746. A dreadful one at Lisbon, in which above 10,000 of the inhabitants perished, 1755. This earthquake extended to Spain, Morocco, Constantinople, France, and England. The year 1783 was rendered remarkable by the destruction of the two Calabrias and part of Sicily; but this was only the beginning of a succession of fatal earth- quakes, which continued to spread desolation over that part of the world for the space of two years.-The list of these awful visitations of Providence might be easily enlarged, but we shall close the enumeration by mentioning two of recent occurrence:–viz. the dreadful earthquake of the Caraccas, in South America, in 1812, by which several cities and towns were ruined, or greatly injured, and many thousands of their inhabitants destroyed –and that of Aleppo, Antioch, and the surrounding country, in 1822, by which 20,000 persons perished, and as many were maimed and wounded. EARTHS. The stony or pulverulent masses, which are the chief component parts of the mountains, valleys, and plains of our globe, consist of a few substances called earths, as barytes, strontites, lime, silica, magnesia, alumina or clay, glucine, zirconia, yttria, and thorina. They are incombustible but very little soluble in water or alcohol; have little or no taste; their specific gravity less than most of the metals; when pure, they assume the form of a white powder; infusible, capable of com- bining with the acids, insipid to the taste, disposed to unite with the alkalies, sulphur, or phosphorus, and each other, either by fusion or solution in water. The class of earths will always be of important consideration with mankind. It is not unlikely that hereafter the other earths may be decomposed, and found to be oxides in like manner. EARTHs, in Chemistry, are all those stones which we tread under foot, but which consist of a few elementary principles. These earths are silex, alumine, magnesia, glucine, yttria, and zircon, which, when freed from foreign matters, are generally of a white colour, insoluble in water, incombustible, and not four times the specific gravity of water. & Silea, or Siliceous Earth, is the basis of all substances known by the name of quartz and silex. It has never been found pure in a state of nature, but in combination with other sub- stances, it abounds in almost every country of the globe. Common flint contains ninety-seven parts out of a hundred of silex, it consequently has given its name to this earth, silex being the Latin word for flint. When purified it is a white powder, the particles of which are harsh to the touch, as if they consisted of very minute grains of sand. It is not quite three times as heavy as water, and has neither taste nor smell. Water will not dissolve it, nor any kind of acid, except fluoric. Sir H. Davy has discovered it to have a metallic basis, to which he has given the name of silicium. Silex has various uses in the arts, and is one of the most valuable sub- stances we are acquainted with. In various states of combina- tion it is employed in the making of roads, as an ingredient in glass, for making chemical furnaces and utensils, in the manu- facture of pastes or artificial gems, and for innumerable other useful purposes. - Alumine, is a kind of earth, so called from its forming the basis of alum. It is very soft, compact, and tenacious, about twice the weight of water, and when breathed upon, has a smell which is peculiar to all clayey productions. In the fire it shrinks, and becomes so hard as even to strike fire with steel. It readily absorbs water, and is dissolved by most acids. Some writers state, that pure alumine has been discovered in a native state near Halle, in Germany. It is found in a crys- tallized form, and nearly in a state of purity, in the Oriental ruby and Sapphire. From the different combinations of alumine are made all kinds of earthenware. To the dyer and the calico-printer it is an article of indispensable necessity; and fullers and scourers of cloth employ it with great advantage in their respective operations. Zircon, when freed from those substances with which it is combined, is a white and somewhat rough powder, insipid to the taste, insoluble in water, and about four times as heavy as that fluid. It is found in the two kinds of precious stone called jargoon and hyacinth, and has not hitherto been applied to any useful purpose. Glucine, is a kind of earth of peculiar nature which is found in the emerald and beryl, and when purified forms a soft, light, and white powder, without smell, and of a sweetish taste. . To the last of these qualities it is indebted for its name, which is derived from a Greek word signifying sweet. It is some- what unctuous to the touch, and about three times as heavy as water. The uses of this earth, whatever they may be, are not known. Yttria, is an earth which, amongst other particulars, differs from glucine by its weight, since it is nearly five times heavier than water. In a natural state it occurs as the basis of a black Swedish mineral, called gadolinite. When cleansed by chemical process from all its impurities, it is a fine, white, and inodorous powder. Barytes, is a white, porous, and very heavy earth, which can only be obtained pure by chemical process. It is easily reduced to powder, and is soluble in all kinds of acids. To the taste it is very harsh and caustic, and if taken into the stomach proves an extremely virulent poison. In some respects it agrees with the alkalies, particularly in its property of chang- ing blue vegetable colours to green, and in corroding like them, though with less energy, all kinds of animal substances. From these circumstances it has sometimes been denominated an alkaline earth. Saturated with sulphuric and carbonic acid, it constitutes the minerals denominated sulphate and carbonate of barytes. It has been discovered to have a metallic base, which is called barium. Strontian, is an earth which, like barytes, is not found other- wise than in combination with sulphuric and carbonic acids. It occurs in great abundance in different parts of the world, and when purified, forms a porous mass, of grayish white colour, acrid taste, and somewhat alkaline nature. This earth con- verts vegetable blue colours to green, but does not act.so strongly on animal bodies as barytes, nor is it poisonous like that substance. - º Lime, the basis of all those substances which are denomi- nated calcareous, is only to be obtained in a state of purity by artificial process. Combined with carbonic acid, it forms limestone, chalk, and marble; but correctly speaking, none of these substances are lime, though they are all capable of being converted into such by burning. Lime may also be obtained from oyster and other sea shells. When pure, it is of a white colour, and moderately hard substance, though easily reducible to powder. Its taste is burning and acrid, and, like the alka- lies, it changes vegetable blue colours to green. It has like- wise the property of corroding and destroying animal tº sub- stances. Lime, when pure, absorbs water with great avidity, 252 E C L E. B. E. DICTIONARY OF MECHANICAL SCIENCE, becomes hot, and falls into powder. Even merely exposed to the open air, it gradually attracts moisture, and assumes a powdery form; soon after which it becomes saturated with car- bomic acid from the atmosphere, and is thereby again converted into carbonate of lime. It occurs abundantly in almost every country, but always in combination with some acid, carbonic, sulphuric, boracic, fluoric, or phosphate. This substance has a metallic basis, which has been denominated calcium. The particular uses of lime will be hereafter detailed. Magnesia, is a light and perfectly white kind of earth, of soft powdery appearance, without taste or smell, and some- what more than twice as heavy as water. It is not found in this pure state in nature, but may be prepared from Epsom salt, which consists of magnesia in union with sulphuric acid. The slightly acrid taste observable in, the magnesia used in medicine, arises from a portion of lime which it contains. This substance does not dissolve in water, but is soluble in every kind of acid. It has the property of changing delicate blue colours to green. - EASE THE SHIP, the command given to the steersman to put the helm close to the lee-side, or, in the sea phrase, hard-a- lee, when the ship is expected to pitch or plunge her fore part deep in the water, while close-hauled. The reason usually given for this practice is, that the sudden movement of the helm prevents the ship's head from falling with so much weight and rapidity into the hollow of the sea, as it would otherwise do; which is presuming, that the slow, and uncertain effect of the helm is sufficient to retard the certain and violent action of gravity, a position that necessarily infers a very singular theory of mechanics. We shall not endeavour to advance any argu- ment in favour of this practice, only to remark, that it is most religiously observed both in merchant ships and his majesty’s navy. g ASTER, a Festival of the Christian church, observed in memory of our Saviour’s resurrection. The Asiatic churches kept their Easter on the same days the Jews observed their passover; and others, on the first Sunday after the first full moon in the new year. This controversy was determined in the council of Nice, when it was ordained, that Easter should be kept on one and the same day, which should always be a Sunday. But though the Christian churches differed as to the time of celebrating Easter, all agreed in shewing particular respect to this festival. EAU-DE-LUCE, a volatile preparation, thus made: ten or twelve grains of white soap are dissolved in four ounces of rectified spirit of wine, after which the solution is strained, and a drachm of rectified oil of amber is added, and the whole is filtrated. Afterwards some strong volatile spirit of sal ammo- nia should be mixed with the solution. EAVES, in Architecture, the margin or edge of the roof of a house, being the lowest tiles, slates, or thatch, that hang over the walls, to throw off the water at some six or nine inches from the wall. EBB, the reflux of the tide, or the return of it back from the highest of the ſlood, usually termed full sea, or high water. EBENUS, the Ebony Tree, a genus of the decandria order, in the diadelphia class of plants, and in the natural method ranking under the 32d order, papilionaceae. There are two spe- cies. 1. The cretica, a native of Crete and other islands in the Archipelago, rises with a shrubby stalk three or four feet high, which puts out several side branches with hoary leaves at each joint, composed of five narrow spear-shaped lobes, which join at their tails to the foot-stalk, and spread like the fingers of a hand. The branches are terminated by spikes of purple flow- ers. 2. The pinnata, a biennial, and also a native of the Levant, constitutes the genus ebenus of botanists; but that which is called ebony wood, and which is brought from the Indies, is hard and heavy, susceptible of a fine polish, and on that account is used in inlaid works, &c.; the most usual ebonies are black, red, and green, which come from Madagas- car and the island of St. Maurice. Black ebony, preferred to the others, is now much less used than formerly, since the discovery of so many ways of giving other hard woods a black colour. The green ebony, besides Madagascar and St. Mau- rice, grows in the Isle of Tobago. Of red ebony, called also grenadilla, we know little more than the name. Cabinet- makers, in-layers, &c. make ‘pear tree and other woods pass for ebony, by giving them a black colour with a strong decoc- tion of galls, to which is added a small quantity of vitriolated IrOrl. . . . sº EBULLITION, the act of boiling up with heat, when a fluid, as water, is passing off from a state of fluidity to that of an uniform gas, in consequence of the application of heat, which converts the water into vapour or steam. . . . ECCENTRIC, in Geometry, denotes two circles, or spheres, which, though contained in some measure within each other, yet have not the same centre; and is thus opposed to concen: tric, which indicates that two figures have a common centre. In Astronomy, the eccentric place of a. planet is its place as seen from the sun, and which, when referred to the ecliptic; coincides with the heliocentric longitude. And the eccentricity. of a planet is the distance between the centre and focus of the ellipsis in which it revolves. - IECCLESIASTICAL COURTS, as the Archdeacon's, the Consistory, the court of Arches, the Peculiar's, the Prerogative, and the court of Delegates. - - ECHENEIS, the Remora, in Ichthyology, a genus belonging to the order of thoracici, of which there are two species. 1. The remora, or sucking-fish. 2. The neucrates ; both natives of the Indian ocean. They were often found adhering so strongly to the sides of sharks and other great fish, as to be got off with difficulty. - - . ECHINUS, in Zöology, the sea hedge-hog, a genus of insects belonging to the order of vermes mollusca. - ECHO, a sound reflected, or reverberated from a solid con- cave body, and thence repeated to the ear. See Acoustics. ECLECTICS, ancient Philosophers, who, without attaching themselves to any particular sect, selected whatever appeared to them the best and most rational from each. º ECLIPSE of the SUN, is an occultation of part of the face of the sun, occasioned by an interposition of the moon between the earth and the sun, consequently all eclipses of the sun happen at the time of new moon. i Eclipse of the Moon, is a privation of the light hf the moon, occasioned by an interposition of the earth between the sun and the moon, consequently all eclipses of the moon happen at full. moon; for it is only when the moon is in opposition, that it can come within the shadow of the earth, which must always be on that side of the earth which is from the sun. The earth being in the plane of the ecliptic, the centre of its shadow is always in that plane; if therefore the moon be in its nodes, that is, in the plane of the ecliptic, the shadow of the earth will fall upon it; also, since this shadow is of considerable breadth, it is partly above and partly below the plane of the ecliptic; if therefore the moon in opposition be so near one of its nodes, that its latitude is less than half the breadth of the shadow, it will be eclipsed. But, because the plane of the moon’s orbit makes an angle of more than five degrees with the plane of the ecliptic, it will frequently have too much latitude at its opposi- tion to come within the shadow of the earth. s Now let S represent the sun, as in the figure, m the moon between the earth and the sun, a E G b a portion of the earth's orbit, e and f two places on the surface of the earth. The dark part of the moon's shadow is called the umbra, and the light part the penumbra ; and it is evident, that if a specta- tor be situated on that part of the earth where the umbra falls, that is between e and f, there will be a total eclipse of the sun at that place; at e and f, in the penumbra, there will be a partial eclipse, and beyond the penumbra there will be no eclipse. As the earth is not always at the same distance from the moon, if an eclipse should happen when the earth is so far from the moon that the lines Fe and Cf cross each other before they come to the earth, a spectator situated on the earth, in a direct E. C. L. E D I 253 DICTIONARY OF MECHANICAL SCIENCE. line between the centres of the sun and moon, would see a ring of light round the dark body of the moon, called an annular eclipse; when this happens, there can be no total eclipse any where, because the moon’s umbra does not reach the earth. People situated in the penumbra will perceive a partial eclipse; and an eclipse can never be annular longer than 12 minutes 24 seconds, nor total longer than 7 minutes 58 seconds, nor can the duration of an eclipse of the sun ever exceed two hours. The sun being larger than the earth, the shadow of the earth is a cone, the base of which is on the surface of the earth, and the moon is eclipsed by a section of the earth's shadow. If the earth were larger than, or equal to, the sun, its shadow would either perpetually enlarge, or be always of the same dimension; but in this case the superior planets would sometimes come within it, and be eclipsed, which never happens. Therefore, the sun is larger than the earth, and produces a shadow from the earth of a conical form, which does not extend to the orbit of Mars. - - An eclipse of the moon is partial, when only a part of its disc is within the shadow of the earth ; it is total, when all its disc is within the shadow ; and it is central, when the centre of the earth's shadow falls upon the centre of the moon's disc. Let S represent the sun, E G the earth, and m the moon in the earth’s umbra, having the earth between her and the sun ; D EP and H G P the penumbra. Now, the nearer any part of the penumbra is to the umbra, the less light it receives from the sum, as is evident from the figure; and as the moon enters the penumbra before she enters the umbra, she gradually loses her light and appears less brilliant. The duration of an eclipse of the moon, from her first touching the earth’s penumbra to her leaving it, does not exceed five hours and a half. The moon does not continue in the earth's umbra longer than three hours and three - quarters, in any eclipse, neither is she totally eclipsed for a longer period than one hour and three-quarters. As the moon is actually deprived of her light during an eclipse, every inhabitant upon the face of the earth who sees the moon, sees the eclipse. An eclipse of the sun, as we have said, happens when the moon, passing between the sun and the earth, intercepts the Sun's light, and the sun can only be eclipsed at the new moon, or when the moon, at its conjunction, is in or near one of its nodes. For unless the moon is in or near one of its nodes, it cannot appear in or near the same plane with the sun ; with- out which it cannot appear to us to pass over the disc of the Sun. At every other part of its orbit, it will have so much northern or southern latitude, as to appear above or below the sun. If the moon be in one of its modes, having no altitude, it will cover the whole disc of the sun, and produce a total eclipse, except when its apparent diameter is less than that of the sun; if it be near one of its nodes, having a small degree of latitude, it will only pass over a part of the sun's disc, or produce a partial eclipse. In a total eclipse of the sun, the shadow of the moon falls upon that part of the earth where the eclipse is seen, and there- fore a spectator, placed any where in the centre, will not see ' any part of the sun, because the moon will intercept all the rays of light coming directly from the sun; and it is manifest, that in this situation the moon, being an opaque body, will cast its shadow upon the part of the earth where the eclipse is total. In a partial eclipse of the sun, a penumbra, or imperfect shadow of the moon, falls upon that part of the earth where the partial eclipse is seen. If the moon, when new, is in one of its nodes, the eclipse of the sun will be central. For then the centres of the earth, sun, and moon, being all in the plane of the ecliptic, and being now con- centric, the centre of the moon will pass between the sun's centre and that of the earth. The penumbra of the moon, in a oentral eclipse, will not cover the whole disc of the earth; for the semidiameter of the moon's penumbra being equal to the Sum of the apparent semidiameters of the sun and moon, about 16. 23". × 15', 37", or 32. at the medium, its diameter is about 64. whereas the diameter of the earth's disc is about 120. whence the penumbra cannot cover the whole disc. The height of the shadow of the moon is about 60} semidiameters of the earth. The semiangles of the earth's shadow and of the moon's shadow, being each equal to the sun's apparent ated in the middle of the zodiac. semidiameter, the angles are equal to one another, and these cones are similar. Therefore, as the semidiameter of the base of the earth’s shadow, (that is, of the earth,) is to the semidiameter of the base of the moon's shadow, (that is, of the moon,) so is the height of the earth's shadow to the height of the moon’s shadow. Now the semidiameter of the earth is to that of the moon nearly as 100 to 28, and the height of the earth’s shadow is about 217 semidiameters of the earth; whence the height of the moon’s shadow is equal to about 60% semi- diameters of the earth; for 100 : 23 :: 217 60+ nearly. An eclipse of the sun is said to be annular, when at the time of the eclipse a ring of the sun appears round the edges of the moon; and a central eclipse of the sun will be an annular one, if the distance of the moon from the earth at the time of the eclipse be greater than its mean distance. Were the orbit of the earth and that of the moon both in the same plane, there would be an eclipse of the sun every new moon, and an eclipse of the moon every full moon. But the orbit of the moon makes an angle of five degrees and a quarter with the plane of the earth’s orbit, and crosses it in two points called the nodes. Astronomers have calculated, that if the moon be less than 17° 21' from either node, at the time of new moon, the sun may be eclipsed; or if less than 11° 34' from either node, at the full moon, the moon may be eclipsed ; at all other times there can be no eclipse, for the shadow of the moon will fall either above or below the earth at the time of new moon; and the shadow of the earth will fall either above or below the moon, at the time of full moon. To illustrate this, suppose the right hand part of the moon’s orbit, as in the figure, to be elevated above the plane of the paper, or earth's orbit, it is evi- dent that the earth's shadow, at full moon, would fall below the moon: the left hand part of the moon’s orbit at the same time would be depressed below the plane of the paper, and the shadow of the moon, at the time of new moon, would fall below the earth. In this case, the moon’s nodes would be between E and a, and between G and b, and there would be no eclipse, either at the full or new moon; but, if the part of the moon’s orbit between G and b be elevated above the plane of the paper, or earth's orbit, the part between E and a will be depressed, the line of the moon’s nodes will then pass through the centre of the earth and that of the moon, and an eclipse will ensue. An eclipse of the sun begins on the western side of his disc, and ends on the eastern ; and an eclipse of the moon begins on the eastern side of her disc, and ends on the western. The average number of eclipses in a year is four, two of the sun, and two of the moon; and, as the sun and moon are as long below the horizon of any particular place as they are above it, the average number of visible eclipses in a year is two, one of the sun and one of the moon. ECLIPTIC, in Astronomy, is a great circle in which the sun makes his apparent annual progress among the fixed stars. It is the real path of the earth round the sun. The intersection at 23° 28′ is called the equinoctial points; the ecliptic is situ- The apparent path of the sun is either in the equinoctial, or in lines nearly parallel to it, and his apparent annual path may be traced in the heavens, by observ- ing what particular constellation in the zodiac is on the meri- dian at midnight; the opposite constellation will shew, very nearly, the sun's place at noon on the same day. EDDY, the water that by some interruption in its course runs contrary to the direction of the tide or current, and appears like the motion of a whirlpool. EDGINGS, among Gardeners, the series of small but dura- ble plants, set round the edges or borders of flower-beds, &c. The best and most durable plant for this use is box, which, if well planted and rightly managed, will continue in strength and beauty many years. The seasons for planting these are the autumn, and very early in the spring ; and the best species for this purpose, is the dwarf Dutch box. EDICT, an order or instrument signed and sealed by a prince, to serve as a law to his subjects. We find frequent mention of the edicts of the Praetor, the ordinances of that off- cer, in the Roman law. Edicts can have no room in Britain, because laws originate in the parliament, and not in the king. EDITOR, the person who revises or prepares any work for | publication. 3 T 254 E. L. A E L E DICTIONARY OF MECHANICAL SCIENCE. EFFECT, the result or consequence of the application of a cause or agent, on some subject. It is an axiom in philosophy, that effects are proportional to their adequate causes. EFFECTION, denotes the geometrical construction of a proposition; it is also used in reference to problems, which when they are deducible from, or founded upon, some general propositions, are called the geometrical effections of them. EFFERVESCENCE, a small degree of ebullition: the agitation produced by the mixture of an acid and an alkali. EFFICIENT CAUse, that which produces an effect. EFFLORESCENCE, the effect which takes place when bodies spontaneously become converted into a dry powder. It is almost always occasioned by the loss of the water of crys- tallization in saline bodies. Natron is an example of efflo- rescence, when it appears as a salt on the surface of the ground. Alum effloresces in the same way. EFFLUVIUM, in Physiology, the minute particles which exhale from most, if not from all bodies in nature ; a sort of invisible vapour, sensible only by its effect on the organ of smelling. Effluvia however in some cases become visible, con- stituting that which in animals and plants makes the matter of perspiration. - - EFFORT, a term frequently used by mathematicians and philosophers, to denote the force by which a body in motion tends to produce an effect, whether the effect be really pro- duced, or impeded by any obstacle which intervenes. EGGS. The eggs of hens, and of birds in general, are com- posed of several distinct substances. 1. The shell, or external coating, which is composed of carbonate of lime '72, phosphate of lime 02, gelatine '03. The remaining 23 are perhaps water. 2. A thin, white, and strong membrane, possessing the usual characters of animal substances. 3. The white of the egg, for which see ALBUMEN. 4. The yolk, which consists of an oil, united with a portion of serous matter, sufficient to render it diffusible in cold water, in the form of an emulsion, and con- crescible by heat. Yolk of egg is used as the medium for rendering resins and oils diffusible in water. Preservation of Eggs for many Years.-Dip them in a solu- tion of gum arabic in water, and imbed them in powdered charcoal. Charcoal being a non-conductor of heat, a uniform temperature will be preserved when moved from one climate to another. The method of preserving eggs by dipping them in boiling water, which destroys the living principle, is too well known to need further notice. EIGHT, a number consisting of twice four. ordinal number, the next after the seventh. EJECTMENT, in Law, is a mixed action, by which a lessee for years, when ousted, may recover his term and damages; it is real as to the lands, but personal as to the damages. ELAEIS, a genus of plants belonging to the natural order of palmae. There is one species, from the fruit of which, resem- bling an olive in shape, the negroes extract the palm oil. |BLASTIC, that power which a body has of returning to the form from which it has been distorted. Thus the branch of a tree, the blade of a sword, &c. are said to be elastic, because if they are bent to a certain degree and then let go, they will of themselves return to their original form. Hence Elastic JBodies are such as admit of having their form altered by the application of a force or pressure, on the removal of which they will recover their original form or figure. In this respect all bodies which come within our knowledge, are comprehended under one of these three distinctions. If two bodies, when pressed together, suffer an alteration in their form, and if after- wards, on removing that pressure, they recover their original figures, they are called elastic. If, when pressed, their forms are not in the least altered, they are called hard. And if, when being pressed as above, they alter their forms, and retain the same after the pressure is discontinued, they are called soft. And both these last kind of bodies are termed non-elastic. We know, however, of no bodies that are perfectly hard, soft, or elastic, but all partake of these properties in a greater or less degree. Water was for a long time supposed to be incom- pressible, and perfectly non-elastic, but experiment shews, that this supposition was erroneous; and air, which is the most elastic fluid we know of, is now known not to possess this pro- perty in a perfect degree. EIGHTH, an The principal Phenomena observable in Elastic Bodies.—1. A pººl elastic body has a tendency to restore itself with the same force with which it is pressed or bent. 2. An elastic body exerts its force equally on all sides, but the effect is found principally where there is the least resistance. 3. Elastic bodies, in whatever manner they are struck or bent, are reflected, and rebound with the same force in an opposite direction ; thus an elastic body will rebound from the plane on which it impinges, with the same velocity with which it meets it, and so as to make the angle of reflection equal to the angle of incidence. 4. A perfectly fluid body (being defined, that which cannot be compressed,) cannot be elastic. 5. A perfectly solid body cannot be elastic. 6. The elasticity of most bodies, particu- larly of long and slender forms, may be easily shewn, and even in very hard and compact bodies their elasticity may be mani- fested in various ways; thus, for instance, let a marble slab, or a flat and smooth iron, be covered with black lead, or with printing ink; then drop an ivory ball upon it from different heights, and the degree of compression on it will be indicated by the magnitude of the spot which will be found upon the ivory ball. ELAstic Curve, is the name that James Bernoulli gave to the curve which is formed by an elastic blade, fixed horizontally by one of its extremities in a vertical plane, and loaded at the other extremity with a weight, which by its gravity bends the blade into a curve, the determination of which involves inves- tigations of the most intricate order. This curve is the same which a perfectly flexible right line would form itself into when supported at its two extremities, and loaded with an uniform fluid which fills the whole cavity of the curve, and is therefore not the same as the catenary, though frequently confounded with that curve. ELAstic Fluids, are those which are possessed of an elastic property, as air, steam, &c. ELAstic Gum, the same as caoutchouc, or Indian rubber. ELASTICITY, is that property of bodies by which they restore themselves to their original figure after compression. Various hypotheses have been advanced by philosophers to account for this important property, some attributing it to one cause, and some to another; it is, however, now more generally supposed to arise from the presence of caloric, and the attrac- tive and repulsive powers that have place between the minute particles which constitute a body, whether it be a solid or fluid. ELATINE. A vegetable principle lately discovered in the juice of the seeds of the momordica elaterium, or cucumber. It is most violently purgative. ELBOW in the Hawse, is when a ship, being moored in a tideway, swings twice the wrong way, thereby causing the cables to take half a round turn on each other. ELDERS, among the Jews, persons of great age, experience, and wisdom. Elders, in the Presbyterian discipline, are officers who, with the ministers and deacons, compose the sessions of the kirk. The elders’ business is to assist the minister in visiting the congregation upon occasion, to watch over the morals of the people of his district, and to give them private reproof in case of any disorder; but if the scandal be gross, or the person obstinate, he lays the thing before the session. Elders are chosen from among the most substantial, knowing, and regular people, by the session or consistory of the kirk. There is a ruling elder in every session: he should be a man of spotless character, and of principal consideration and interest in his parish ; he is chosen out of the kirk session: the congre- gation is to approve of the choice: the minister ordains him before the congregation: he may be chosen to assist in any church judicatory, and in all manner of government and disci- pline, for he has an equal vote with the remainder. ELECTION, in Numbers, is the different ways of taking any number of quantities given; in combination thus, the quantities a b c may be taken different ways, as a b c, or a b, a c, and a, b, c. ELECTIVE Attraction. The principle of all chemical operations, which enables us to decompose certain bodies, and to compound others, is, that every substance has a certain peculiar affinity for other substances, but not in an equal degree. Chemical affinity observes certain laws, which are called the laws of affinity, and which are as follow:—Chemical affinity exerts its action between a number of bodies, simple or com . E L E E L E 255 DICTIONARY OF MECHANICAL SCIENCE. pound, and unites them chemically into one whole. Soda will combine with sulphuric acid, forming a different substance from either; viz. sulphate of soda. The power of chemical affinity is in an inverse ratio to that of corpuscular attraction. The agency of the affinity of composition, or chemical affinity, is either assisted or retarded by different degrees of tempera- ture. Chemical affinity is accompanied by a change of tempe- rature, as in the mixture of sulphuric acid with water. The agency of chemical affinity between two or more bodies, may be dormant until it be called into action by the interposition of another, which frequently exerts no energy upon either of them in a separate state. Metals are not affected by acids until water be present. The degree of energy in chemical affinity acting between various bodies, is different in different sub- stances. Nitric acid has more affinity for potash than for iron. The action of chemical affinity is either limited or unlimited ; in other words, chemicals are capable of uniting in definite or in indefinite proportions. The degree of chemical affinity of different bodies, is modified in proportion to the quantities or masses of the substances employed. + ELECTRICITY, the name of an unknown natural power which produces a great variety of peculiar and surprising phe- nomena, the first of which are supposed to have been observed in the mineral substance called amber, whence they have been denominated electrical phenomena, and the laws, hypotheses, experiments, &c. by which they are explained and illustrated, form together the science of electricity. The electric property of amber was known to Thales, who lived about 600 years before our aera, though Theophrastus, who flourished about 300 years after Thales, is the first author who makes any distinct remark on this subject. Some other of the ancients also speak slightly on this head, but still they confined its action to the two substances amber and jet, and knew nothing farther of its effect except its power of attracting light sub- stances after being excited by friction. Electricity may there- fore be considered as a modern science of no higher date than about the year 1600, when Gilbert, a native of Colchester, and a physician in London, published his treatise “De Magnete,” in which are contained many considerable experiments and discoveries. Boyle, Otto Guericke, Dr. Wall, and some others, made a few ingenious experiments; but it was not before the year 1709 that any important step had been made in this science. In this year Hawksbee wrote on the subject of elec- tricity, and noticed the great electrical power of glass, and the light proceeding from it; he also first heard the noise attending the excitation, and a variety of other phenomena relating to electrical attraction and repulsion; at the same time he intro- duced a glass globe into the electrical apparatus; and to this he was indebted for many of his most important discoveries. After an interval of twenty years, Stephen Grey established a new aera in the history of electricity. To him we owe the discovery of communicating the power of native electrics to other bodies in which it cannot be excited, by supporting them on silken lines, hair lines, cakes of resin, or glass, and a more accurate distinction than had hitherto obtained between elec- trics and non-electrics: he also shewed the effect of electricity on water, more obviously than had been done by Gilbert. The experiments of Grey were repeated by M. du Fay, mem- ber of the Academy of Sciences at Paris, to which he added many new observations and discoveries of his own. Desagulier followed Grey by adding many experiments to the science. But the most remarkable discovery that had yet been made in this science, was in the end of the year 1745, and beginning of 1746. This was the method of giving the électric shock, or the accumulation of the power of electricity in a vial. This had its name of the Leyden Vial, from Cunaeus, a native of Leyden, who exhibited it as he was repeating some experi- ments made by Messrs. Muschenbroek and Allamand, profes- sors in the university of that city. It is said he was not, how- ever, the inventor. The merit of this discovery (if any merit can be ascribed to a discovery made by accident) belongs to Mr. Van Kleist, dean of the cathedral at Camin. Soon after this, however, a method of giving the shock was discovered in Holland, by Cunaeus; and the discovery of this powerful effect pf the electric fluid immediately raised the attention of all the philosophers in Europe. Electricity rose to that celebrity it has now attained, by the united labours of successive indivi- duals, among whom Cavendish, Priestley, and Franklin, are illustrious. - - ELECTRICAL Machine, denotes the principal part of the elec- tric apparatus, so constructed as to be capable of exciting a great quantity of the electric fluid, and exhibiting its effects in a very sensible manner. A great variety of forms have been given to electrical machines, either for the sake of convenience, or in order to render their effects more powerful; we shall, however, only explain one of the most simple forms, as con- structed by the late Mr. Adams, which is represented in the following figure, and may be described as follows:—The cylinder FG HI, is supported by two. strong perpendicu- lar pieces D E. The axis of one cap of the cylinder moves in a small hole, at the upper part of one of the supports, and the opposite axis passes through the upper part of the other support. To this end the handle or winch is fitted, and the cush- ion is supported and insulated by a glass pillar, the lower part of which - is fitted into a wooden socket, to which a regulating screw is adapted, to increase or diminish the pressure of the cushion against the cylinder. A piece of silk comes from the under edge of the cushion, and lies on the cylinder, passing between it and the cushion, and proceeding till it nearly meets the collecting points of the conductor. The more strongly this conductor is made to adhere to the cylinder, the stronger is the degree of excita- tion. Before the cylinder, or opposite to the cushion, is a metallic tube Y Z, supported by a glass pillar L. M. This is sometimes called the prime conductor, often only the conduc- tor; and for the more conveniently trying experiments on the two powers, and exhibiting the diſferent states of the cushion and conductor, there are two wires to be fixed occasionally, the one to the conductor, the other to the cushion; on the upper part of these are balls furnished with sliding wires, that they may be set apart from each other at different distances. The annexed figure represents another view of the Electrical Plate Machine, the construction of which will be readily com- prehended by the different letters which are referred to the same parts in both views. - - A Before the electrical machine is put in motion, examine those parts which are liable to wear, either from the friction of one surface against | another, or to be injured by the dirt that may insinuate itself between TC the rubbing surfaces. If any grat- () ing or disagreeable noise is heard, the place whence if proceeds must be wiped clean. and rubbed over with a small qdantity of tallow ; a little of which should also be occa- L sionally applied to the axis of the cylinder itself. If the screws by which the frame is fixed are loose, they should be tightened. Having examined the different parts of the machine, and put them in order, the glass cylinder, and the pillars which support the cushion and conductor, should be well wiped with a dry silk handkerchief, to free, them from the moisture which glass attracts from the air, being particularly attentive to leave no moisture on the E L E E L E DICTIONARY OF MECHANICAL SCIENCE. ends of the cylinder, as any damp on these parts carries off the electric fluid, and weakens the force of the machine; in very damp weather it will be proper to dry the whole machine, by placing it at some little distance from the fire. Care should be taken that no dust, loose threads, or filaments, adhere to the gylinder, its frame, the conductors, or their insulating pillars; because these will gradually dissipate the electric fluid, and prevent the machine from acting powerfully. When you are satisfied of this, rub the glass cylinder first with a clean, coarse, dry, warm cloth, or a piece of wash leather, and then with a piece of dry, warm, soft silk; do the same to all the glass insulating pillars of the machine and apparatus; these pillars must be rubbed more lightly than the cylinder, because, being warnished, they may be damaged by too much friction. ... We come now to consider electrics and conductors, which may be disposed according to the order of their perfection, beginning in each column with the most perfect of their class. Thus, glass is a more perfect electric than amber, and gold is a better conductor than silver. Electrics. Conductors. Glass of all kinds. All the metals in the following All precious stones, the most order: Gold, silver, platina, brass Iron, tin, quicksilver, lead, The semi metals. Metallic ores. Charcoal. The fluids of the animal body. Water, especially salt water, and other fluids, except oil. Ice, snow. - Most saline substances. transparent the best. Amber. Sulphur. All resinous substances. Wax, silk, and cotton. Dry external animal substan- ces, as feathers, wool, &hair. Paper. Loaf sugar. Air, when dry. Oils and metallic oxides. Ashes of animal and vegetable substances. Smoke, steam, and even a Most hard stones. Va CUIU. Iſl. Professor Lapostolle, of Amiens, has discovered that straw possesses the quality of serving as a conductor to lightning and hail. Repeated experiments have convinced him, that straws united together serve equally well as the iron rods now fixed upon buildings for the former purpose, at the same time that they are not attended with similar inconvenience. In gonsequence of this discovery, the common buildings may be secured from the effects of lightning in the most economical manner; and even crops on the land may be protected from the ravages which they sometimes suffer from hail. It may be proper in some cases to place a hot iron on the foot of the conductor, in order to evaporate the moisture which would otherwise injure the experiments. It may also be observed, that, l. To excite the machine, it is requisite to clean the cylinder, and wipe the silk. 2. Grease the cylinder, by turning it against a greasy leather, till it is uniformly obscured. The tallow of a candle will answer this purpose. 3. Turn the cylinder till the silk flap has wiped off so much of the grease as to render it semi-transparent. 4. Spread some amalgam on a piece of leather, and apply this against the turning cylinder. By this means the friction will immediately increase, and the leather must not be removed till it seems to have attained its maximum ; then discontinue the application of it, and the effect of the machine will be found very powerful. The best kind of amalgam is made of zinc and quicksilver. If a little of the latter be added to melted zinc it renders it easily pulverizable, and more quicksilver must be added to the powder if very soft amalgam is required. - The following statement seems to comprise the general principles, on which this wonderful fluid is known to act:— The electric fluid is probably the same in essence with that of light and heat, but combined with a substance which affects the organs of smell. When bºdies are electrified by glass, they furnish tufts or pencils of light; but if electrified by sulphur, they only produce points or sparks of light; bodies presented to those electrified by glass produce only luminous sparks; while those which are presented to bodies which are electrified by sulphur, present beautiful pencils or tufts of light. Bodies are electrified either by friction or communication. To electrify bodies by communication, it is necessary to insulate them; and the substances most proper for insulating others; are those which electrify best by friction, Glass electrifies both by friction and communication, and the energy of the fluid is augmented in the conductors by an increase of surface. The pencils or tufts of light, seen at the extremities of electri- fied bodies, are composed of divergent rays when they pass through the air, but to pass a permeable conducting body, they sometimes become convergent. , - . . Animal Electricity.—Some fishes have the property of giving shocks analogous to those of artificial electricity; namely, the torpedo, the gymnetus electricus, and the silurus electricus. If the torpedo, whilst standing in water, or out of water, but not insulated, be touched with one hand, it generally communi- cates a trembling motion or slight shock to the hand. If the torpedo be touched with both hands at the same time, one hand being applied to its under and the other to its upper sur- face, a shock will be received exactly like that occasioned by the Leyden phial. The shock given by the torpedo when in air, is about four times as strong as when in water; and when the animal is touched on both surfaces by the same hand, the thumb being applied to one surface, and the middle finger to the opposite, the shock is felt much stronger than when the circuit is formed by both hands. The gymnotus electricus, or electrical eel, possesses all the electric properties of the tor- pedo, but in a superior degree. When small fish are put into the water wherein the gymnotus is kept, they are generally stunned or killed by the shock, and then they are swallowed, if the animal be hungry. The strongest shock of the gymnotus will pass a very short interruption of continuity in the circuit. When the interruption is formed by the incision made by a penknife on a slip of tinfoil that is pasted on glass, and that slip is put into the circuit, the shock, in passing through that interruption, will shew a small but vivid spark, plainly to be seen in a dark room. The gymnotus seems also to be possessed of a sort of new sense, by which he knows whether the bodies presented to him are conductors or not. This fact has been ascertained by a great number of experiments. Electrical Instruments and Apparatus.-The experiments in electricity are so various, that the apparatus used may be increased almost agreeably to every man's fancy; and in general, he who wishes to make new experiments, will find it necessary to make an addition suitable to the object of his inquiry. It will be, therefore, most consistent with the design of this work, to describe only those parts of the apparatus which are most essential to the performance of popular expe- riments. The instruments commonly employed in this branch of science may be classed under six heads:—1st. The instru- ments used for earciting electricity, viz. glass tubes, plates, and cylinders; 2nd. Those for conducting the electric matter, which are chiefly METALs ; 3rd. Those intended for accumulating the fluid, or, in technical language, for receiving a charge, such as coated bottles or jars, commonly called LEYDEN PHIAls; 4th. Those which are intended to produce more formidable effects, such as ELECTRIC BATTERIES ; , 5th. The instruments employed for ascertaining the quantity of electricity, called electroMeters; and lastly, those employed for retaining the electric power. The discharging rod needs no explanation: it is shewn in the figure, R, as applied to a Leyden Phial, A D. This jar is coated with tinfoil on the inside and outside, within about three inches of the top of its cylindrical part, and having a wire with a round brass knob, or ball, A, at its extremity. This wire passes through the cork, or wooden stopper, D; at its lowest ex- tremity is a piece of chain that touches the inside coating in several parts. To charge this jar, a communication is made between the electrical machine and the brass knob A, while the outside of the jar communicates with the earth by the table or the hand. Bring the knob. A of the jar near the prime conductor, and after a few turns of the machine the jar will be charged; that is, the inside of the jar will be positively, and the outside negatively, electri- fied ; or if the inside is negatively, the outside will be posi- tively, electrified. R is a discharging rod, which is used to convey the superabundant electricity from one side to the other, where there is less than the natural share. The discharging rod consists of two brass knobs, a a, attached to wires, which move round a joint a, fixed to a glass handle R. The operator E L E E L E 257 DICTIONARY OF MECHANICAL SCIENCE. holds the discharging rod by the glass handle R, and applies the brass knobs to the ball and jar, as shewn in the figure, when an explosion takes place proportional to the quantity of electricity it had received. If any number of persons join hands, and one holds a chain that is in communication with the jar, while the last of the company touches the jar, a shock will be received. . - Of the Electric Spark.-The spark that shines between the two bodies is capable of setting combustible matters on fire. If a body, containing only its natural share of electricity, be presented sufficiently near to a body electrified, positively or negatively, a quantity of electricity will force itself through the air, from the latter to the former, appearing in the form of a spark. When two bodies approach each other sufficiently near, one of which is electrified positively, and the other nega- tively, the superabundant electricity rushes violently from one to the other, to restore the equilibrium between them. This effect takes place if the two bodies be connected by a con- ducting substance. The electric spark has not only the appear- ance of fire, but is capable of actually setting fire to various substances that are easily inflamed. The sense of feeling, seeing, and hearing, are not only affected by electricity, but it is even sensible to the smell and the taste. The electric spark goes to a greater or less distance through the air, in order to reach a conductor, according as its quantity is greater or less; as the parts from which it proceeds, and on which it strikes, are sharper or more blunt, and as the conductor is more or less perfect. The strength of the machine is known from the length and density of the sparks it gives. That the charge of a coated jar resides in the glass, and not in the coating, is proved in the following manner:—Set a plate of glass between two metallic plates, about two inches in diameter, smaller than the plate of glass; charge the glass, and them remove the upper metallic plate; by an insulated handle, of metal which have not been electrified, but insulated—the plate of glass thus coated afresh will still remain charged. The Electrical Bells consist of - three small bells suspended from Z-S a narrow plate of metal, the two R S outermost by chains, and that in "Sº Y the middle (from which a chain, . silken string. Two small knobs of brass are also hung by silken strings, on each side of the bell, which serve as clappers. If an S apparatus of this kind is joined IF) to one of those conducting rods erected to protect buildings from the effect of lightning, it will serve to give notice of the The Electrical Battery has been described; see BATTERY. The instruments for ascertaining the presence and the quan- tity of electricity in different bodies are various, but the sim- plest of all are little balls of cork, or rather of the pith of elder, which is still lighter, and suspended by silk threads. When brought into contact with an electrified body, the balls will immediately diverge, and, according to the degree of diver- body in question is electrified. A similar effect will be pro- duced by a light and downy feather. The pith balls are called Canton's electrometer. - For more particular admeasurement, that is, for . ascertaining precisely the degree to which any body is electrified, an instrument somewhat less simple is required, and the quadrant electrometer, sists of a perpendicular stem formed at the top like a ball, and furnished at its lower end with a brass ferule and pin, by which it may be fixed in a hole made in the conductor of the electrical machine or of a Leyden jar. To the upper part of the stem a graduated ivory semicircle is fixed, about the middle of which is a brass arm or cock, to sup- take up the glass plate, and place it between two other plates S R, passes to the floor) by a approach and passage of an electrical cloud. gence, a judgment may be formed of the degree to which the as in the figure, is in most general use. It con- port the axis of the index. The index is a very slender stick, which reaches from the centre of the graduated conductor. arch to the brass ferule, and to its lower extremity is fastened a small pith ball, nicely turned in a lathe. When this elec- trometer is in a perpendicular position, and not electrified, the index hangs parallel to the pillar; but when it is electrified, the index recedes more or less, according to the quantity of electricity. Lane's discharging electrometer, as it is commonly called, is employed chiefly by the practitioners of medical electricity. Medical Electricity.—In judging of cases proper to be elec- trified, experience shews, that in general, all kinds of obstruc- tions, whether of motion, of circulation, or of secretion, are very often removed or alleviated by electricity. The same also may be said of nervous disorders; both which include a great variety of diseases. The application of electricity has also been found a powerful remedy in muscular contractions. But when any limb is deprived of motion, it must be observed, that the deprivation has not always originated in a contraction of the muscles, but that it is often occasioned by relaxation; thus, for instance, if the hand be bent inwardly, the patient has no power of straightening it; the cause of it may be a weakness of the outward muscles, as well as a contraction of the inward ones. In such cases, it is difficult, even for ana- tomists, to discover the real cause ; but the surest method is to electrify not only those muscles which are supposed to be con- tracted, but also their antagonists; for, to electrify a sound muscle is by no means hurtful. Rheumatic disorders of long standing are relieved, and frequently cured, by only drawing the electric fluid with a point from the part, or by drawing sparks from the conductor; the operation should be continued for about four or five minutes, repeating it once or twice every day. When strong shocks are administered, their greatest number should not exceed 12 or 14, except when they are to be given to the whole body in different directions. The instru- ments, which, besides the electrical machine and its prime con- ductor, are necessary for the administration of medical elec- tricity, may be reduced to three, viz. an electric jar, with Lane's electrometer; an insulated chair, or an insulated stool, upon which a chair may be occasionally set, and the directors. The Identity of Lightning , and Electricity.—Dr. Franklin proved, by a variety of experiments, that the lightning spark of electricity, and the lightning that flashes from the clouds in a thunder storm, are exactly of the same kind, and operate in the same manner, &c. The particulars in which lightning and the electric ſluid agree, are, 1. Flashes of lightning are gene- rally seen crooked, and waving in the air, as the electric spark, when it is drawn from an irregular body at some distance. 2. Lightning strikes the highest and most pointed objects in its way, in preference to others; as high hills, and trees, towers, spires, masts of ships, points of spears, and the like. In like manner, all pointed conductors receive or throw off the electric fluid more readily than those that are terminated by flat sur- faces. 3. Lightning is observed to take the readiest and best So does electricity in the discharge of the Leyden phial. For this reason Dr. Franklin supposes, that it would be safer, during a thunder storm, to have one's clothes wet than dry, as the lightning might then, in great measure, be transmitted to the ground, by the water on the outside of the body. It is found, he says, that a wet rat cannot be killed by the explosion of the electrical bottle, but that a dry rat may. 4. Lightning causes combustion, so does electricity. Dr. Franklin says, that he could kindle with it, hard dry resin, spirits unwarmed, and even wood. 5. Lightning sometimes dissolves metals: so does electricity. 6. Lightning has often been known to strike people blind. And a pigeon, after a vio- lent shock of electricity, by which the doctor intended to have killed it, was observed to have been struck blind. 7. Light- ning destroys animal life. Animals have likewise been killed by the shock of electricity. The largest animals which Dr. Franklin and his friends have been able to kill, were a hen, and a turkey which weighed about ten pounds. Thunder is merely the noise produced by the motion of lightning. The reason why we do not hear the dreadful noise of the thunder, as soon as we see the lightning, is, because sound is longer in arriving to our ears, than light to our sight. Light moves almost instantaneously, Sound moves no more than 1142 feet in a second. • ‘ - 3 U 258. E I, E E L E DICTIONARY OF MECHANICAL SCIENCE, distant from the basis of A. : The Thunder House Experiment;--The effects of the electric matter, when it. strikes a building, and the method oſpre- Tº venting it, are exemplified by an instru-, ment called the thunder house, represent- ing the side of a house, either furnished * a board about three-quarters of an inch (+4. with a metallic conductor or not, A is • * * * * * * hiº and shaped like the gable end of ºx||U% a house. This board is fixed perpen- |r % dicularly upon the bottom board B, upon A=}ºsºft which the perpendicular glass pillar C * is also fixed, in a hole about eight inches small hole I L KM, about one- fourth of an inch deep, and nearly one inch wide, is made in the board A, and is filled by a square piece of wood of nearly the same dimensions, it being necessary that it, should fit, the hole, in order to drop out by the least shaking of the instru- ment. A wire I K, is fastened diagonally to this square piece of wood. Another wire L H, of the same, thickness, having a brass ball, H, screwed on its pointed extremity, is fastened on the board A, so also is the wire M N, which is shaped in a ring at N. From the upper extremity of the glass pillar C, a crooked wire proceeds, having a spring socket F, through which a double-knobbed wire slips perpendicularly, the lower knob G of which falls just above the knob H. The glass pillar C must not be made very fast in the bottom board, but it. IIaust be fixed so that it may be easily moved round its own axis, by which means the brass ball G may be brought either nearer or farther from the ball H without touching the part E.F G. Now when the square piece of wood LIM K (which may represent the shutter of a window or the like) is fixed into the hole, so that the wire I K stands, in the direction L. M., then the metallic communication from H to N is completc, and the instrument resembles a house furnished with a proper conductor; but if the square piece of wood LIM K is fixed, so that the wire I K stands in the direction I K, as represented in the figure, then the metallic conductor H N, from the top of the house to its bottom, is interrupted at L. N, in which case the house is not properly secured. Fix tha piece L. I.M. K, so that the wire, may be as repre- sented in the figure, in which case the metallic conductor H N is discontinued. Let the ball G be fixed perpendicularly about half an inch distance from the ball H. M., only turning the glass pillar C, remove the former ball from the latter; by a wire or chain, connect the wire E F with the wire G of the jar P, and let another wire or chain, fastened to the hook. N, touch the outside coating of the jar. Connect the wire G with the prime conductor, and charge the jar; then by tarning the glass, pillar C, let the ball G come gradually near the ball H, and when | they are arrived sufficiently near one another, the jar will be discharged, and the piece of wood L.I. M. K will be pushed out of the hole to a considerable distance from the thunder house. The ball G in this experiment represents, an electrified cloud, which, when it arrives sufficiently near the top of the house A, discharges into it the electric fluid ; and as the house is not secured by a proper conductor, the explosion breaks part of it, i.e. knocks out the piece of wood I M. Repeat the experi- ment; but let the piece of wood I M be so situated, that the wire I K may stand in the situation L. M., by which the con- ductor H N will not be discontinued: in this case, the explo- sion will have no effect upon the piece of wood L. M., which, shews the utility of metallic conductors for houses. Variation in this Experiment.—Unscrew, the brass, ball H. from the wire H L, so that it may remain pointed, and with only this difference in the apparatus, repeat these two experi- ments; the piece of wood L N will remain immoveable, and no explosion will be heard. The conductor E F G in this ex- periment is supposed to represent a thunder cloud discharging its contents on a weathercock, or any other metallic substance. on the top of a building; hence it may be inferred, that if there is a metallic communication to conduct the electric fluid down. to, the earth, the building will receive no damage; but where. the connexion is imperfect, it will strike from one part to the other, and thus endanger the whole building. Elevated con- ductors applied to buildings to secure them from lightning, will each other. cover also that almost all, the bodies with which we meet, are of a mixed or componnd nature. When we reduce these to the principles of which, they are composed, we find, that the num- ber of simple or unmixed bodies is very limited, and that all the substances with which we are acquainted, are formed. {. a combination, in various proportions, of these simple COOlle.S. stances, of which, in various proportions or combinations, all bodies with which we are acquainted are composed. Formerly, air, earth, fire, and water, were supposed to be the elements of which all bodies are formed. But modern, improvements in in this. manner discharge the electricity from a cloud that passes over them. . . . . - Electrical Phenomena.-The various phenomena of electricity may be divided into four classes, in the first of which may be included all those experiments which serve to illustrate elec- trical attraction; and repulsion; in the second, those produced by the stream of electricity; in the third class may be ranged all those phenomena which are accompanied with luminous appearance; and, lastly, we may enumerate those more formi- dable effects arising from the concentrated electricity, in the experiments with the Leyden phial and the electrical battery. There is a stone, found in many parts of the world called tourmalin, which is sometimes' crystallized as a nine-sided prism, terminated by a three-sided and a six-sided pyramid; when this substance is gently heated, it becomes electrical, and one extremity, that terminated by the six-sided pyramid, is positive, the other is negative: to a certain extent, its elec- tricities are exalted by increasing the temperature; when it begins to cool, it is still found, electrical; but the electricities are changed, the pyramid, before positive, is now negative, and vice versa. When the stone is of considerable size, flashes of light may be seen along its surface. There are other gems and crystallized substances, which possess a property similar to that of the tourmalin. The luminous appearance of some dia- monds, when heated, probably depends upon their electrical excitation. The substance called the boracite, which is a cube, having its edges and angles defective, becomes electrical by" heat, and in one variety presents no less than eight sides, in different states, four positive, four negative; and the opposite poles are in the direction of the axes of the crystal. ELECTUARY, in Pharmacy, a form in which both official and extemporaneous medicines are frequently made. ELEGIT, in Law, a writ of execution, which lies for a per- son who has recovered debt or damages; or upon a recogni- Zance in any court, against a defendant that is not able to satisfy the same in his goods. - ELEMENTARY, any thing relating to the principles or ele- ments of bodies. - ELEMENT, in Physiology, a term used by philosophers, to denote the original component parts of bodies, or those into which they are ultimately resolvable. It was the opinion of the ancient philosophers that there are only four simple bodies; namely, fire, air, water, and earth. To these they gave the name of elements, because they believed that all substances are composed of them. But we now know that these supposed elements are compounds: fire is composed of caloric and light; air of caloric, oxygen, and azotic gases; water of oxygen and hydrogen; and the earth includes various different substances. ELEMENTS of THE PLANets, in Astronomy. See PLANet. ELEMENTs of Geometry, the title of a celebrated and well- known work of Euclid. "See GeoMetRY. - ELEMENTs, in the Higher. Geometry or Analysis, denotes indefinitely small portions of curves, surfaces, and solids. ELEMENTs, in Physics, the first principles, or ingredients, of which bodies are composed. These are supposed to be few in number, unchangeable, and by their different combinations pro- ducing that extensive variety of objects which constitute the works, of nature. - ELEMENTs of Bodies, in Chemistry. When we contemplate the world that we inhabit, we discover a vast variety of sub-. stances differing in their properties of weight, colour, &c. from When we examine these more minutely, we dis- The elements of bodies, then, are those simple sub- chemistry have shewn that this was an erroneous supposition. For it is well known that the air or atmosphere is a mixed body, composed of several aerial.fluids or gases, so that instead. E. L. G. E L L 259 DICTIONARY OF MECHANICAL SCIENCE. of one simple kind of air, it is now known that there are seve- ral sorts of air, essentially different from each other. It is also known, that instead of one simple kind of earth, there are several kinds, quite different. Water is found not to be a simple body, but composed of two different kinds of air united together, With the nature of fire we are very little acquainted; but this we can say, that combustible substances, either burn- ing or otherwise, are not simple substances. From the im- provements that are continually making in the methods of analyzing bodies, or separating them into their component principles or elements, many substances, once supposed to be simple, are found to be compounds; and as chemistry con- tinues to improve, more errors of this kind may be corrected, and our inability to decompose any substance, does not prove it to be a simple body or an element, but only, perhaps, that our methods of analysis are not perfect. For the sake of con- venience, however, we shall, at present consider all bodies as elements or simple bodies, that have not been analyzed or separated into component parts. Almost every body in nature is susceptible of three several states of existence; viz. solid, liquid, and aeriform ; and these states of existence depend upon the quantity of caloric com- bined with the body. The simple substances at present known are divided into three classes; viz. imponderable bodies, as caloric, and light. Supporters of combustion, as oxygen, chlorine, iodine, and fluorine. Combustible and incombustible substances, as carbon, sulphur, phosphorus, hydrogen, nitro- gen, boron, silicon, and the metals. - - ELEPHANT, Elephas, a genus of the mammalia class, of the order bruta. The generic character is, cutting-teeth none in either jaw; tusks in the upper jaw; proboscis very long, prehensile; body nearly naked. There are two species, 1. The elephas maximus, the great elephant. 2. The Sukotyro. The teeth, which are imported into Europe, are generally from Africa, where they are frequently found in woods. The ele- phant is undoubtedly the largest of all terrestrial animals, arriving at the height of twelve feet, though the more general height seems to be from nine to ten feet. Elephants are com- monly found in the midst of shady woods, and they delight in cool spots, near rivers. They are capable of swimming with great ease. Their general food consists of the tender branches of various trees, as well as grains and fruits. The elephant brings usually one young at a time; rarely two ; the young are about three feet high when they are first born, and con- tinue growing till they are sixteen or twenty years old; they are said to live a hundred or a hundred and twenty years. The sukotyro, a native of Java, according to Nieuhoff, who has figured in his travels to the East Indies, is a quadruped of a very singular shape. Its size is that of a large ox; and the snout like that of a hog; the ears round and rough ; and the tail thick and bushy. The eyes, are placed upright in the head, quite differently from those of other quadrupeds. On each side the head, stand the horns, or rather teeth, not quite so thick as those of an elephant. This animal, feeds upon her- bage, and is but seldom taken. ELEVATION, denotes the height or altitude of any object. ELEVATION of the Equator, in Astronomy, is an arch of the meridian, less than a quadrant, intercepted between the equa- tor and the horizon of the place. - ELev ATION of the Pole, is an arch of the meridian intercepted between the pole and the horizon of the place. - : ELEVATION of a Star, is an arch of a vertical circle contained between a star and the horizon, and in the same manner is estimated the elevation of any other of the heavenly bodies. ELEVATION of a Piece of Ordnance, in the theory and practice of projectiles, is the angle the axis of the gun makes with the horizon. . - * ELEVATION, Angle of, in Gunnery, that comprehended be- tween the horizon and the line of direction of a cannon or mor- tar; or it is that which the chase of a piece, or the axis, of its hollow cylinder, makes with the plane of the horizon. ELEVATION, in Perspective, the representation of the whole body or building, as in architecture, elevation signifies the whole or principal face of a building, ELGEBAR, the name of the bright star in the foot of Orion, more commonly called Rigel. • ELIMINATION, in Analysis, that operation by means of which all the unknown quantities except one are exterminated out of an equation, whence the value of that one becomes de- termined, and hence by substitution the value of all the other quantities. , - - ELISION, in Grammar, is the cutting off a vowel or syllable in a word, as in “th’ attempt,” where e is cut off, because coming before a vowel. - ELIXIIt, in Medicine, a compound tincture, extracted from many efficacious ingredients; hence, the difference between a tincture and an elixir seems to be this:—A tincture is drawn from one ingredient, as the tincture of rhubarb, or sometimes with an addition of another, to open it, and to dispose it to yield to the menstruum ; whereas an elixir is a tincture extracted from several ingredients at the same time. g ELK, an animal of the deer kind, with the horns palmated, and without a stem. It is a native of the northern parts of Europe, and is a strong animal, equal in size to a horse, but far less beautiful. - - - ELL, a measure which obtains, under different denomina- tions, in most countries, whereby cloths, stuffs, linens, silks, &c. are usually measured. The ell English, is 5 quarters, or 45 inches; the ell Flemish, 3 quarters, or 27 inches. In Scotland, an ell contains 37 ſº inches English. ELLIPSE, is one of the conic sections, formed by the inter- section of a plane and cone, when the plane makes a less angle with the base than that formed by the base and the side of the cone. The word is derived from #AAstruç, defective, and is thus denominated by Apollonius, because the square of the ordi- nate in this figure is always less than the rectangle of the parameters and abscisses. . . There are three ways in which we may define an ellipse; viz, 1. As being produced by the intersection of a plane and cone, as We find it treated of by Apollonius and all the ancients. 2. According to its description in plano, as it is treated of by several of the moderns. And 3. As being generated by the motion of a variable line or ordinate, along another line or directrix, whereby the properties of the curve are treated of, by means of the equation by which it is defined. . The several lines, and points in and about an ellipse, as the axis, diameters, parameter, foci, &c. will be found defined and explained under the several articles in this Dictionary; and We shall, therefore, in this place merely state some of the prin- cipal properties of the figures, without, however, attempting their demonstration, as that would extend this article to too great a length. tº H Properties of the Ellipse.—1. The IE squares of the ordinates of the axis, are to each other as the rectangle of the abscisses. That is, - AF. F.B.: GF? : : AD. DB : I) E Or if one of the ordinates be taken A I, F | C - - B at the centre as H. C., which thus be- - ºr " come the semiconjugate, then be- I. cause AC . CB = AC", the pro- portion becomes . * AC2 : CH2 : ; AD . DB : I).E.” or by doubling * . - AB2 : HI? : : AD . DIB : DE2 As the square of the transverse axis Is to the square of the conjugate, So is the rectangle of the abscisses To the square of their ordinate. 2. The sum of two lines drawn from the two foci to any point in the curve is always equal to the transverse axis. Fig. 1. That is, if F, f, be the two foci, E and F E, f E, two lines drawn from . them to any point E in the curve, then F E +f E = A B, fig. 1. From this property is derived the , common method of describing the curve mechanically by points, or by a thread thus, fig. 2: . º . In the transverse axis take the foci F, f, and any point I.. Then That is, 260 - E L L E L L DICTIONARY OF MECHANICAL SCIENCE, will the radii A.I., IB, describe, from the centres F, f, two arcs intersect- ing each other in M, which will be a point in the curve. In like manner assume other points I, and thus de- termine other points m, m, &c. Then, with a steady hand a curve-line may be drawn through all the points of intersection, which will be the ellipse required. f Or, otherwise, take a thread of the length A B the transverse axis, and fix its two ends in the foci F, f, (see fig. 2.) Then carry a pen or pencil P, round by the thread, keeping it always stretched, and its point will trace out the ellipse, as is evident from the property above stated. \ Other methods of describing the ellipse in in the subsequent part of this article. 3. If a tangent be drawn to any point in an ellipse, and two lines drawn from the two foci to the point of contact, these plano are given from the two foci be drawn, cians find that the angle of incidence is equal to the angle of two lines will form equal angles with the tangent. That is, if H T be a tan- • t then will the angle T G F = the angle H G f. - It is this property that reflection; it follows from the above property, that rays of light issuing from the one focus, and meeting the -curve in every point, will be reflected back into the other focus, and gent to the ellipse at G, *s-g O’N. £ c E A. `s gives the name foci to the - hence these points are denominated foci, or burning points. and the two lines FG, f G two points F, f, for as opti- I This property may be otherwise illustrated by considering a billiard table in the form of an ellipse, then a ball being f struck so as to pass through one focus in any direction, it will be reflected back again through the other focus, then again through the first, and so on, as long as the ball continues in motion. - * 4. If there be any number of ellipses described on the same transverse axis, and any ordinate be drawn so as to meet all those ellipses, the tangents to the several ellipses at those points will all terminate in one common point in the prolong- ment of the transverse axis. - That is, if A H B, A H B, , be any two ellipses, having the same transverse axis; and D H H’ be any common ordinate, then the two tan- gents HT, H'T, will be terminated in the common point T. And as this is necessarily true when A H B becomes a circle, we have hence an easy method of drawing a tangent to any point in an ellipse; which is as follows: Let H be the point to which a tangent is to be drawn; draw the right ordinate DH, and produce it indefinitely ; on A B describe a semicircle meeting the ordinate produced in H'; join H'C, and draw H'T perpendicular to H' C, meeting the transverse produced in T, then T H will be the tangent required. 5. The ordinate HT, in the circle, is to the ordinate HT of the ellipse, as the transverse axis of the ellipse is to its con- jugate axis. And if a circle were described on the conjugate axis, and an ordinate drawn as before, then the ordinate of the circle would be to the corresponding ordinate in the ellipse, as the conjugate axis of the ellipse is to its transverse. And hence it follows that the area of any ellipse is a mean propor- tional between the area of the circles described on its two axes. 6. Every parallelogram circumscribed about an ellipse, at the extremities of any pair of its conjugate diameters, is equal to the rectangle of its two axes. - 7. The sum of the squares of any pair of conjugate diameters is always equal to the sum of the squares of the two axes of the ellipse. g - Description of the Ellipse in plano.—Besides the two methods of describing an ellipse, given in proposition 2, there are several others, by instrumental operation, of which the follow- ing are the most simple: r q Fig. 1 1. If two rulers FG, f_H, fig. 1. each equal in length to the transverse axis A B, have their extremities' fixed in the foci so as to be moveable round these points; and if the other extre- mities of the rulers be connected by a third ruler H G, which is equal in length to Ff, the distance of the two foci so as to be moveable about the two points H and G ; then if the ruler H G be moved round the centres F and f, the intersection of the rulers F.G., f H, in E will describe the peri- phery of an ellipse, of which A B is the transverse axis, and F, f, the two foci. - 2. Let there be two rulers, A B, H I, fig. 2, set at right angles to each pe other, and let a third ruler, D EP, be moved along, so that the points D and E constantly touch the two rulers A B, HI; so will the point P de- scribe the periphery of an ellipse. On this principle are constructed ELLIPTIC Compasses, which see. 3. If one end C, fig. 3. of any two equal rulers C D, D P, which are moveable about the point D, like a carpenter's joint rule, be fastened to the ruler A B, so as to be moveable about C; and if the end P, of the ruler DP, be drawn along the side of the ruler A B, then any point E, taken a & in the side of the ruler D P, will de- . scribe an ellipse whose centre is C, conjugate axis = 2 EP, and trans- verse = 2 C D – 2 D E. Area of an Ellipse.—Multiply the two axes together, and that product again by '7854, which will be the area required. Area of an Elliptic Segment.—Find the area of the corre- . II sponding circular segment, described on the same axis to which the cutting line or base of the segment is perpendicular. Then as this axis is to the other axis, so is the circular seg- ment to that of the ellipse. Or, find the tabular circular seg- ment whose versed sine is equal to the quotient, of the height of the elliptic segment divided by its axes. Then multiply together this segment, and the two axes of the ellipse, for the area of the segment. ~. ELLIPSIS, in Grammar, a figure in syntax, in which one or more words are not expressed. - ELLIPTIC, or ELLIPTICAL, something relating to an ellipse. ELLIPTIC Arc, is any part of the periphery of an ellipse. ELLIPTIC Compasses. See CoMPAsses. * ELLIPTIC Conoid, the same as spheroid. g + ELLIPTIC Dial, an instrument usually made to fold up for *" * the convenience of the pocket. By this dial is found the meridian, hour of the day, the rising and setting of the sun, &c. ELLIPTIC Spindle, is the solid generated by the revolution of any segment of an ellipse about its chord. : ELLIPTICITY of the TeRRest RIAL SPHERo1D, is the differ- ence between the major and the minor semiaxes; it is gene- rally expressed in terms of the former, that is, of the radius of the equator. The quantity of the ellipticity has been variously, assigned by different mathematicians: Sir Isaac Newton, sup- posing the earth of uniform density, gave ºn for the ellipticity; Boscovich, from a mean of several admeasurements, stated it at #5; Lalande, ºr; Laplace, ºr; Sejour, ºr ; Carouge, ºn ; Krafft, sh; and Playfair, from a theorem of Clairault applied to the heterogeneous spheroid, states it at air. Setting aside those which are deduced from the hypothesis of uniform den- sity, ºn may be admitted as the most probable value of the ellipticity. E M B E M E DICTIONARY OF MECHANICAL SCIENCE. 261 ELOGY, praise or panegyric bestowed on any person or thing, in consideration of its merit. The beauty of elogy con- sists in brevity. Eulogiums should not have so much as one epithet properly so called, nor two words synonymous. They should strictly adhere to truth; for extravagant and improbable elogies lessen the character of the person they would extol. ELONGATION, in Astronomy, the angle under which we see a planet from the sun, when reduced to the ecliptic, or it is the angle formed by two lines drawn from the earth to the sun and planet, when reduced as above. The greatest elongation is the greatest distance to which the planets recede from the sun, which, however, only relates to the inferior planets Mercury and Venus; for it is obvious, that any of the superior planets may be 180° distance from the sun, or in opposition. The greatest elongation of Venus, according to our modern tables, is from 440 57" to 47° 48', and that of Mercury from 17o 36 to 28920. ELOPEMENT, is, when a married woman of her own accord departs from her husband, and dwells with an adulterer; for which, without voluntary reconciliation to the husband, she shall lose her dower. Except that her husband willingly, and without coercion of the church, reconcile her, and suffer her to dwell with him, in which case she shall be restored to her action. By eloping and living apart from the husband, he is discharged of the future debts, and no longer liable to support her. . & - ELVELA, a genus of plants belonging to the cryptogramia class, and the order of fungi. ... • ELY MUS, a genus of plants belonging to the class triandria, ..and in the natural method ranking under the 4th order gramina. EMBALMING, is the opening of a dead body, and having taken out the entrails, filling it with odoriferous drugs and spices, to prevent its putrefying, and then pickling it in a solu- tion of nitre for two months and a half. The body was then wrapped up in bandages of fine linen and gums, and magnifi- cently painted, and placed in a coffin or sarcophagus. EMBARGO, in Commerce, an arrest on ships, or merchan- dise, by public authority; or a prohibition of state, commonly on foreign ships, in time of war, to prevent their going out of port; sometimes to prevent their coming in ; and sometimes both for a limited time. EMBASSADOR, or AMBAss ADoR, a public minister sent from one sovereign prince, as a representative of his person, to another. Embassadors are either ordinary or extraordinary. EMBAYED, the situation of a ship when she is enclosed between two capes or promontories; it is particularly applied when the wind, by blowing strong into any bay or gulf, makes it extremely difficult, and perhaps impracticable, for the vessel thus enclosed to draw off from the shore, so as to weather the capes and gain the offing. - EMBER Weeks, or Days, in the Christian church, are cer- tain seasons of the year set apart for the imploring God’s blessing, by prayer and fasting, upon the ordinations performed in the church at: such times. The ember weeks were formerly observed in different churches with some variety, but were at ºlāst settled as they are now observed, by the council at Placen- tia, anno 1095. EMBERIZA, a genus of birds belonging to the order of passeres, of which there are 24 species, among which the most remarkable are, The nivalis, or great pied mountain-finch of Ray, and the snow-bird of Edwards; it has white wings, but the outer edges of the prime feathers are black; the tail is black, with three white feathers on each side. These birds are called in Scotland snow-flakes, from their appearance in hard weather. They arrive in that season among the Cheviot-hills, and in the Highlands in flocks. The miliaris, or gray emberiza, is of a grayish colour, spotted with black on the belly, and the orbits are reddish. It is the bunting of English authors. The hortillana, or ortolan, has black wings; the first three feathers on the tail are white on the edges, only the two lateral are black outwardly. The orbits of the eyes are naked and yellow; the head is greenish, and yellow towards the inferior man- dible. . It feeds principally upon the millet, grows very fat, and is reckoned a delicate morsel by certain epicures, especially when fattened artificially. *Mºst the act of a servant secreting or making arrived there. away with property intrusted to him. It is felony, and subjects the offender and his abettors to transportation. g EMBOLIMAEAN, and EMBolis Mic, Intercalary, is chiefly used in speaking of the additional months inserted by chrono- logists to form the lunar cycle of 19 years. - EMBOLISMUS, in Chronology, signifies intercalation. As the Greeks made use of the lunar year, which is only 354 days, in order to bring it to the solar, which is 365 days, they had every two or three years an embolism, i.e. they added a 13th lunar month every two or three years, which additional month they called embolimaeus, because inserted or intercalated. EMBOLUS, the piston or sucker of a pump. EMBOSSING, or IMRossING, in Architecture and Sculp- ture, the forming or fashioning works in relievo, whether cut with a chisel or otherwise. EMBRACERY, an attempt to corrupt or influence a jury, or any way incline them to be more favourable to the one side than the other, by money, promises, letters, threats, or persua- sions'; whether the juror give verdict or not, or whether the verdict given be true or false, which is punished by fine and imprisonment; and the juror taking money, perpetual infamy, imprisonment for a year, and forfeiture of tenfold the value. EVIBRASURE, in Fortification, a hole or aperture in a parapet, through which the cannon are pointed to fire into the moat or field. - - EMBROCATION, in Surgery and Pharmacy, an external remedy, consisting in an irrigation of the part with some pro- per liquor, as oil, spirits, &c. EMBROIDERY, a work in gold or silver, or silk thread, wrought by the needle upon cloth, stuffs, or muslin, into various figures. In embroidering stuffs, the work is performed in a kind of loom, because the more the picce is stretched, the easier it is worked. As to muslin, they spread it upon a pat- tern ready designed, and sometimes, before it is stretched upon the pattern, it is starched, to make it more easy to handle. EMBRYO, in Physiology, the first rudiments of an animal in the womb, before the several members are distinctly formed; after which period it is denominated a foetus. EMERALD, is a well-known gem of pure green colour, somewhat harder than quartz. Its natural form is either rounded, or a short six-sided prism. By the ancients the emerald was in great request, particularly for engraving upon. They are said to have procured it from Ethiopia and Egypt. The most intensely coloured and valuable emeralds that we are acquainted with are brought from Peru. They are found in clefts and veins of granite, and other primitive rocks, and oftentimes grouped with the crystals of quartz, felspar, and mica. The emerald is one of the softest of the precious stones, and is almost exclusively indebted for its value to its charming colour. The brilliant purple of the ruby, the golden yellow of the topaz, the celestial blue of the sapphire, are all pleasing tints; but the green of the emerald is so lovely, that the eye, after glancing over all the others, finds delight in resting upon this. In value it is rated next to the ruby ; and when of good colour, is set without foil, and upon a black ground, like bril- liant diamonds. Emeralds of inferior lustre are generally set upon a green gold foil. These gems are considered to appear to greatest advantage when table cut, as in the figure, and sur- rounded by brilliants, the lustre of which forms ~- an agreeable contrast with the quiet hue of the ) emerald. They are sometimes formed into pear- - shaped, ear-drops, but the most valuable stones / are generally set in rings. A favourite mode of setting emeralds among the opulent inhabitants of South America, 1s to make them up to clusters of artificial flowers on gold stems. The largest emerald that has been mentioned, is one said to have been possessed by the inhabitants of the Valley of Manta, in Peru, at the time when the Spaniards first It is recorded to have been as big as an ostrich's egg, and to have been worshipped by the Peruvians, under the name of the Goddess or Mother of Emeralds. They brought smaller ones as offerings to it, which the priests dis- tinguished by the appellation of daughters. Many fine emeralds are stated to have formerly been bequeathed to different monasteries on the continent; but the greatest part of them are said to have been sold by the monks, and to have had their 3 X 262 E N A. E N C DICTIONARY OF MECHANICAL SCIENCE. place supplied with coloured glass imitations. These stones are seldom seen of large size, and at the same time entirely free from flaws. The emerald, if heated to a certain degree, assumes a blue colour, but it recovers its own proper tint when cold. When the heat is carried much beyond this it melts into an opaque, coloured mass. The Oriental emerald is a variety of the ruby, of a green colour, and an extremely rare €II). § EMERGENT YEAR, in Chronology, is the first year of any particular aera. t EMERSION, in Astronomy, is the re-appearance of the sun, moon, or a planet, after having been eclipsed by the interposi- tion of the moon, earth, or other body. This term is sometimes also used to denote the re-appearance of a star, which had been hid in the sun's rays. Emersion is also used to denote the rising of a solid body above a ſluid in which it floats. Minutes or Scruples of EMERsion, in a lunar eclipse, is the arc of the moon’s orbit which she has passed over, from the time she begins to emerge out of the earth's shadow, to the end of the eclipse. EMERSON, WILLIAM, a very eccentric man, but an excel- lent mathematician, born in 1701 at Hurworth, in the county of Durham ; had a small paternal estate of about £70 per annum, to which he for some time added the profits of a small day-school; this, however, he afterwards discontinued, and lived upon the income of his estate, and the trifling profits arising from his works, which were very numerous. Emerson died on the 20th May, 1782, in the 81st year of his age. EMERY, is a very hard mineral of blackish or bluish gray colour, is chiefly found in shapeless masses, and mixed with other minerals. It contains about 80 parts in 100 of alumine, and a small portion of iron, is usually opaque, and about four times as heavy as water. The best emery is brought from the Levant, and chieſly from Naxos, and other islands of the Grecian Archipelago. It is also found in some parts of Spain; and is obtained from a few of the iron mines in our own coun- try. In hardness it is nearly equal to adamantine spar, and this property has rendered it an object of great request in various arts. It is employed by lapidaries in the cutting and polishing of precious stones ; by opticians, in smoothing the surface of the finer kinds of glass, preparatory to their being polished; by cutlers, and other manufacturers of iron and steel instruments; by masons, in the polishing of marble; and in their respective businesses, by locksmiths, glaziers, and numerous other artisans. For all these purposes, it is pulver- ized in large iron mortars, or in steel mills; and the powder, which is rough and sharp, is carefully washed, and sorted into five or six different degrees of fineness, according to the description of work in which it is to be employed. EMETIC, a medicine which induces vomiting. EMetic Tartar, the old name for tartrite of antimony. EMINENTIAL EQUAtion, a term used by some authors for a certain assumed equation, which involves in itself several particular equations. EMOLLIENTS, in Medicine and Pharmacy, such remedies as soften the asperity of the humours, and relax and supple the solids. EMPIS, in Zöology, a genus of insects belonging to the order diptera, the proboscis of a horny substance, bivalve, reflected under the head and breast, and longer than the thorax. There are five species. EMULGENT, or ReNAL ARteries, those which supply the kidneys with blood ; being sometimes single, and sometimes double on each side. EMULSION, a milky-looking fluid, caused by an imperfect combination of oil with water by means of mucilage, gluten, &c. All oily farinaceous seeds, as nuts, almonds, linseed, &c. form an emulsion by trituration with water; yolk of egg, which is a natural compound of oil and albumen, makes a similar emulsion. ENAMEL PAINTING, is performed on plates of gold, silver, or copper, with certain metallic or earthy colours, melted by intense heat. Fine enamelling should only be practised on plates of gold. Nor must the plate be made flat; as in that case, the enamel cracks; but in the form of a watch-glass, and not too thick. The plate being well forged, the operation is begun by laying on a coat of white enamel on both sides, which prevents the metal from blistering, and this first layer serves for the ground of the other colours. The plate being prepared, the subject to be painted is drawn with red vitriol, mixed with oil of spike, marking all parts of the design lightly with a pencil. The colours, which are previously ground with water, extremely fine, in a mortar of agate, and mixed with oil of spike, are laid on. The painting is afterwards gently dried over a slow fire to evaporate the oil, and the colours melted to incorporate them with the enamel, making the plate red-hot. Any part of the painting effaced, is passed over again, strength- eming the shades and colour, committing it again to the fire; and this is repeated till the work is finished. This painting is employed in miniature. - ENAMEL possesses all the properties of glass, except its transparency. The basis of enamels is a pure crystal glass or frit, ground together with a fine calx of lead and tin, with the addition of a small proportion of the white salt of tartar. These form the principal ingredients of all enamels, which are made by adding pulverized colours, and thoroughly incorpo- rating the whole in a furnace. Enamels are used to counter- feit or imitate precious stones, as well as for painting ; or by enamellers and artists working in gold, silver, and other metals. That used by jewellers is brought chiefly from Venice, or Holland, in cakes. * * * ENCAUSTIC PAINTING, was in use among the ancients, who employed wax to give a gloss to the colours, and to pre- serve them from injury. The art was restored by Count Caylus, in 1753. The wood or cloth, stretched on a frame, is rubbed over with bees’ wax, being at the same time held over, or before a fire, at such distance that the wax may gradually melt, while it is rubbed on. It must diffuse itself, penetrate the body, and fill the texture of the cloth, which, when 'cool, is fit to be used. But to make the colours, which are ground in water, adhere to the wax, the whole surface is first rubbed over with Spanish chalk, or white, the colours are then applied. When the picture is dry, it is put near the fire, by which the wax is melted, and the colours absorbed. They are not liable to fade or change ; no damp or corrosive substance can affect them; they have no tendency to crack; and, if by accident they receive injury, they can be easily repaired. About the year 1787, a Miss Greenland, who acquired some knowledge in this art at Florence, communicated, with the pre- sentation of a painting, her method of proceeding, to the Society of Arts. Her directions are the following:—“Take an ounce of white wax, and the same weight of gum mastich, powdered. Put the wax in a glazed earthen vessel, over a very slow fire; and when it is quite dissolved, strew in the mastich, a little at a time, stirring the wax continually, until the whole quantity of gum is perfectly melted and incorporated ; then throw the paste into cold water, and when it is hard take it out of the water, wipe it dry, and beat it in one of Mr. Wedgewood's mortars, observing to pound it first in a linen cloth, to absorb some drops of water that will remain in the paste, and prevent the possibility of reducing it to a powder, which must be so fine as to pass through a thick gauze. It should be pounded in a cold place, and but a little while at a time; as after long beating, the friction will in a degree soften the wax and the gum, and instead of their becoming a powder they will return to a paste. “Make strong gum-arabic water; and when you paint, take a little of the powder, some colour, and mix them together with the gum water. Light colours require but a small quantity of the powder, but more of it must be put in proportion to the body and darkness of the colours; and to black there should be almost as much of the powder as colour. “Having mixed the colours, and no more than can be used before they get dry, paint. with fair water, as is practised in painting with water colours, a ground on the wood being first painted of some proper colour, prepared in the same manner as is described for the picture; walnut tree and oak are the sorts of wood commonly made use of in Italy for this purpose. The painting should be very highly finished, otherwise, when varn- ished, the tints will not appear united. “When the painting is quite dry, with rather a hard brush, passing it one way, varnish it with white wax, which is put E N G E N G, DICTIONARY OF MECHANICAL SCIENCE. 263 into an eartben vessel, and kept melted over a very slow fire till the picture is varnished, taking great care that the wax does not boil. Afterwards hold the picture before the fire, near enough to melt the wax, but not to make it run; and when the varnish is entirely cold and hard, rub it gently with a linen cloth. Should the varnish blister, warm the picture again, very slowly, and the bubbles will subside. When the picture is dirty, it need only be washed with cold water.” The Society considered, that. Miss Greenland's method provides against all inconveniences; and the brilliancy of the colours in the picture painted by her, and exhibited to the Society, fully justifies the opinion, that the Art of Painting in Wax, as above described, merited the reward of a gold pallet, which was voted to her on this occasion. ENCHASING, or CHASING, is the art of enriching and beautifying gold, silver, and other metal work, by some designs or figures represented thereon in low relievo, as on watch cases, cane heads, tweezer cases, &c. This is done by punch- ing or driving out the metal from a figure from that withinside, so as to stand out prominent from the surface of the metal. To understand this delicate business,it should be seen performed by its ingenious artisan. ENCLOSURE, a fence, wall, or hedge, or other means of protection and security surrounding land. Countries, how- ever, in general, lie open, with nothing but banks and ditches to divide the land of every husbandman; but in England, each separate farm is divided from others by hedges and fences, and the farms themselves are broken into small enclosures. In France, Germany, Italy, Spain, and most other nations, the lands still remain unenclosed in large open fields; and those countries, in consequence, present a dreary appearance to the eye of an Englishman, whose enclosures render England the garden of the world. Enclosures greatly improve the * climate of a country, by protecting it from inclement winds; they pleasantly subdivide the labours of the farmer; and by restraining the exercise of cattle, they occasion them to get fat much sooner. ENDEMIC Diseases, those to which the inhabitants of particular countries are subject more than others. ENDOW MENT, in Law, denotes the settling a dower on a woman, and sometimes for settling a provision for a church, college, or hospital. ENFILADE, in the art of war, signifies firing along a trench or other place, and is equivalent to raking a ship. Hence trenches are usually dug in a zig-zag manner, that they may never be enfiladed, or shot along their whole length. ENFRANCHISEMENT, in Law, the incorporating a per- son into any society or body politic ; such as the enfranchise- ment of one made a citizen of London, or other city, or burgess of any town corporate, because he is made partaker of its liberties, or franchises. • ENGAGEMENT, in a naval sense, implies a battle at sea, or an action of hostility between single ships, squadrons, or fleets of men of war. The engagements of the ancients were usually carried on in two different manners. Advanced by their oars, the galleys ran violently aboard of each other, and by the encounter of their beaks and prows, and sometimes of their stems, endeavoured to dash to pieces or sink their enemies. For this purpose the prow was armed with a brazen point or trident, nearly as low as the surface of the water. Some of the galleys were furnished with turrets and buildings, for attack or de- fence. The soldiers annoyed their enemies with darts, slings, swords, and javelins; and in order that their weapons might be directed with greater force and certainty, the ships were equipped with platforms above the deck. The sides of the ships were fortified with a thick fence of hides, which served to repel the darts of the adversaries, and to cover their own sol- diers, who thereby annoyed the enemy with greater security. As to bore and sink the enemy’s ships with the rostra was the chief manner of sea-engagements among the ancients; high and bulky ships had accordingly a great advantage over their adversaries, by the force of the stroke of a large ship. The height was likewise no small convenience in boarding and throwing missile weapons, so that it was much more true among them than among us, that a little ship durst not lay her side to a great one; and though great ships were commonly bad sea-boats, they had a superior force in a sea engagement, the shock of them being sometimes so violent as to throw the crew on the upper deck of smaller ships overboard. This occa- sioned the ancients gradually to increase the bulk of their ships, till they came at last to an enormous size, and then machines, now unknown, were employed in naval engagements; but the following are a few which we find recorded by the ancient writers: g The Dolphin, a large massy piece of lead or iron in the form of a dolphin, and suspended by blocks at the mast heads or yardarms, and ready for a proper occasion, was let down violently from thence into the adverse ships, and either pene- trated through their bottom, and opened a passage for the enter- ing waters, or by its weight immediately sunk the vessel. The Drepanan, an engine of iron, crooked like a sickle, and fixed in the top of a long pole, cut asunder the slings of the sail yards, and thereby let the sails fall down, to disable the vessel from escaping, and incommode her during the action. Similar to this was another instrument, armed at the head with a broad two-edged blade of iron, to cut away the ropes that fastened the rudder in the vessel. There were also spears or maces of an extraordinary length, sometimes exceeding twenty cubits; also certain machines for throwing large stones into the enemy’s ships. w - Another engine was suspended to the main mast, and re- sembled a battering-ram, for it consisted of a long beam and a head of iron, and was with great violence pushed against the sides of the enemy’s galleys. The grappling iron, which was usually thrown into the adverse ship by means of an engine, facilitated the entrance of the soldiers appointed to board, on wooden bridges, that were generally kept ready for this pur- pose in the fore part of the vessel. The arms used by the ancients rendered the disposition of their fleets very different, according to the time, place, and circumstances. They generally considered it an advantage to be to windward, and to have the sun shining directly on the front of their enemy. The order of battle chiefly depended on their power of managing the ships, or of drawing them readily into form; and on the schemes which their officers had con- certed. The fleet being composed of rowing vessels, they lowered their sails previous to the action: they presented their prows to the enemy, and advanced against each other by the force of their oars. Before they joined battle, the admirals went from ship to ship, and exhorted their soldiers to behave gallantly. All things being in readiness, the signal was dis- played by hanging out of the admiral's galley a gilded shield, or a red garment or banner. During the elevation of this, the action continued, and by its depression or inclination towards the right or left, the rest of the ships were directed how to attack or retreat from their enemies. To this was added the sound of trumpets, which began in the admiral's galley, and continued round the whole fleet. The fight was also begun by the admiral's galley, by grappling, boarding, and endeavour- ing to overset, sink, or destroy the adversary. Sometimes, for want of grappling irons, they fixed their oars in such a manner as to hinder the enemy from retreating. If they could not manage their oars as dexterously as their antagonist, or fall alongside to board him, they penetrated his vessel with the brazen prow. The vessels approached each other as well as their circumstances would permit, and the soldiers fought hand to hand till the battle was decided ; nor indeed could they fight otherwise with any certainty, since the shortest distance rendered their slings and arrows, and almost all their offensive weapons, ineffectual, if not useless. The squadrons were some- times ranged in two or three lines parallel to each other; being seldom drawn up in one line, unless when formed into a half moon. This order appears the most convenient for rowing vessels that engage by advancing their prows towards the CIO BIY) V, ; famous machine, called the Corvus, was erected on the prow of their vessels, in the shape of a round piece of timber of about a foot and a half diameter, and about twelve feet long; on the top whereof, they had a block or pulley. Round this piece of timber they laid a stage or platform of boards, four feet broad, and about eighteen feet long, which was well 264 E N G, JE N G, DICTIONARY OF MECHANICAL SCIENCE. framed and fastened with iron. and it moved about the aforesaid upright, piece of timber, as on a spindle, and could be hoisted up within six feet of the top; about this was a sort of a parapet, knee-high, which was de- fended with upright bars of iron, sharpened at the end; towards the top whereof there was a ring: through this ring, fastening a rope by the help of the pulley, they hoisted or lowered the engine at pleasure, and so with it attacked the enemy's vessels, sometimes on their bow, and sometimes on their broadside. ... When they had grappled the enemy with those iron spikes, if they happened to swing broadside to broadside, then they entered from all parts; but in case they attacked them on the bow, they entered, two and two, by the help of this machine, the foremost defending the fore part, and those that followed, the flanks; keeping the top of their bucklers level with the top of the parapet. - ~. - - The Romans were restrained by a treaty with Carthage from sailing beyond the Fair Promontory, &c. but they resolved to contend for the dominion of the sea with the Carthaginians, who had held it uncontested from their ancestors, and began anew by building a whole fleet, after the model of one of their enemy's galleys that was stranded on their coast; and as they never wanted expedients in their military concerns, they placed banks of rowers on board, in the same form as those of the galleys, and instructed their men to strike and recover their oars by a proper signal, till they were so perfect in the exer- eise, and so expert in the discipline and management of their fleet, (which was improved with the Corvus, for the purpose of boarding, as already described), that they soon defeated their enemies. The two consuls were in the two admirals’ galleys, in the front of their two distinct squadrons, each of them just ahead of their own divisions, and abreast of each other : the first division being posted on the right, and the second on the left, making two long files or lines of battle. And when it was necessary to give to each galley a due space to ply their oars and keep clear one of another, and to have their heads or prows looking somewhat outwards; this manner of drawing up did therefore naturally form an angle, the point whereof was at the two admirals' galleys, which was near together; and as their two lines were prolonged, so the distance grew consequently wider and wider towards the rear. And because the naval as well as the land army, consisted of four legions, the ships accordingly made four divisions, two of which were behind: of these, the third fleet or the third legion was drawn up front- wise, in the rear of the first and second, and so stretching along from F. to point, composed a triangle, whereof the third line was the base. Their vessels of burden that carried their horses, baggage, &c. were in the rear of these, and by the help of small boats provided for that purpose, were towed or drawn after them. In the rear of all was the fourth fleet, called the Tri- arians, drawn up likewise in rank or frontwise, parallel to the third ; but these made a longer line, by which means the extre- mities stretched beyond the two angles at the base. This was a body of great strength, not easily broken, and excellently disposed for the ships in the rear to succour, relieve, and come in the place of, any that should fail in front. * . For the reader's more immediate conception of these pre- parations, we here annex the order of battle: Q O . First Division * * Second Division % 3% * & * # Third * * * * * * * * * Division Vessels of * * * * * Burden Fourth * * * * * * * * * * * * Division. At the battle of Ecnomus, between the Romans, and Car- thaginians, the fleet of the former was thus ranged into a wedge in front, and towards the middle of its depth into two right parallel lines. That of the latter was formed into a rectangle or two sides of a square, of which one branch extended behind, and as the opening of the other prosecuted.]. the attack, was ready to fall upon the 'flank of such of the Roman galleys as should attempt to break their line. Ancient The entrance was long-wise, sition. of it would be unnecessary. history has preserved many of these orders, of which some have been followed in later times. Thus, in a battle in 1340, the English fleet was formed in two lines, the first of which contained the larger ships, and the second consisted of all the smaller vessels used as a reserve to support the former where- ever necessary. In 1545 the French fleet, under the command of the Mareschal d’Armebault, in an engagement with the English in the Channel, was arranged in the form of a crescent. The whole of it was divided into three bodies, the centre being composed of thirty-six ships, and each of the wings of thirty. He had also many galleys, but these fell not into the line, being designed to attack the enemy occasionally. This last dispo- sition was continued down to the reigns of James I. and Louis XII. - The invention of gunpowder took place in 1330, and the use of fire-arms was gradually introduced into naval war, without finally superseding the ancient method of engagement. The Spaniards were armed with cannon in a sea-fight against the English and the people of Poitou, abreast of Rochelle, in 1372; and this battle is the first in which mention is made of artillery in our navies. Many years elapsed before the marine arma- ments were sufficiently provided with fire-arms; and in the reign of Charles V. machines were continued in use. So great a revolution in the manner of fighting, and which necessarily introduced a total change in the construction of ships, could not be suddenly effected; but ships are no longer formed of rowing vessels, or composed of galleys, but of ships of the line, which engage under sail, and discharge the whole force of artillery from their sides, being disposed in no other form than that of a right line parallel to the enemy; every ship keep- ing close hauled upon a wind on the same tack. Indeed, the difference between the force and manner of fighting of ships and galleys rendered their service in the same line incom- patible. When we consider, therefore, the change introduced both in the construction and working of ships, occasioned by the use of cannon, it necessarily follows, that squadrons of ships-of-war must appear in the order that is now generally adopted. Finally, the ships ought to present their broadsides to the enemy, and to sail close upon a wind in the wake of each other, as well to retain their own uniformity, as to pre- serve or acquire the advantage which the weather-gage gives them over their adversary. Of all the weapons used by the ancients, the pike and the sword are the only ones now remaining, the others having been totally supplanted by those machines which originated with the invention of gunpowder. Our naval engagements are, therefore, almost generally decided by fire-arms, of which there are several kinds, known by the general name of artillery; and the fire- arms of a ship of war are distinguished into cannon mounted on carriages, swivel cannon, grenadoes, and musquetry. The Swivel cannon is a small piece of artillery, carrying a shot of half a pound, and fixed in a socket on the top of the ship's side, stern, or bow, and also in her tops. The trunnions of this piece are contained in a sort of iron crotch, whose lower end terminates in a cylindrical pivot resting in the socket, so as to support the weight of the cannon. The socket is bored in a strong piece of oak, reinforced with iron hoops, in order to enable it to sustain the recoil. By means of this frame, which is called the swivel, and an iron handle on its cascabel, the gun may be directed by hand to any object. It is, there- fore, very necessary in the tops, particularly when loaded with musketballs, to fire down on the upper decks of the adver- Sary, in action. The Grenado, a little shell, of the same diameter as a four- pound bullet, weighs about two pounds, and is charged with four or five ounces of powder. Grenadoes are thrown from the tops by the hands of the seamen. They have a touch-hole in the same manner as a shell, and a fuse of the same compo- The sailor fires the fuse with a match, and throws the grenado as he is directed; the 'powder being inflamed, the shell instantly bursts into splinters, that kill or maim whom- soever they reach on the decks of the enemy. As this instru- ment cannot be thrown by hand above 15 or 16 fathoms, the ship must be rather near, to render it useful in battle. As to the musket or firelock, it is so well known that a description E N G, E N G, 265 DICTIONARY OF MECHANICAL SCIENCE. * Besides these machines, there are several others used in merchant ships and privateers, as carabines, cohorns, fire- arrows, &c. r - The Carabine, a sort of a musquetoon, the barrel of which is rifled spirally from the breech, so that when the ball, which is forced into it, is again driven out by the strength of the powder, it is lengthened about the breadth of a finger, and marked with the rifle of the bore. This piece has an iron rammer; the barrel, including the stock, is three feet long. It has a much greater range than the musquet; because the rifle of the barrel im- pedes the ball, which thereby makes the greater resistance at the first inflammation of the powder, and giving time for the whole charge to take fire before it goes out of the bore, it is at length thrown out with greater force than from the common musquet. The Cohorn, a sort of small mortar, fixed by a swivel, and particularly used to discharge grenadoes or cast bullets into merchant vessels, when boarded. . . The Fire-arrow, a small iron dart, furnished with springs and bars, together with a match impregnated with powder and sulphur, which is wound about its shaft, is intended to fire the sails of the enemy, and is, for this purpose, discharged from a musquetoon or swivel-gun. The match, kindled by the explo- sion, communicates the flame to the sail against which it is directed, where the arrow is fastened by means of its bars and springs. This is peculiar to hot climates, particularly the West Indies; the sails, being extremely dry, are instantly inflamed, and, of course, convey the fire to the masts and rigging, and finally to the vessel itself. 4. The Organ, a machine consisting of six or seven musquet barrels fixed upon one stock, so as to be fired all at once. A general engagement of fleets or squadrons of ships of war being nothing else than a variety of particular actions of single ships with each other in line of battle, it will be necessary first to describe the latter, and then proceed to represent the usual manner of conducting the former. The whole economy of a naval engagement may be arranged under the following heads: 1. The preparation; 2. The action; and 3. The repair, or refitting for the purposes of navigation. The preparation is begun by issuing an order to clear the ship for action, which is repeated by the boatswain and his mates at all the hatchways or staircases leading to the different batteries. In a ship of war, the management of the artillery requiring a number of men, the officers and sailors are conse- quently restrained to a narrow space in their usual habitations, to preserve the internal regularity of the ship. Accordingly, the hammocks, or hanging beds, of the latter are crowded together as close as possible between the decks, each of them being limited to the breadth of 14 inches, and they are hung parallel to each other, in rows stretching from one side of the ship to the other, nearly throughout her whole length, so as to admit of no passage but by stooping under them. While sus- pended in this situation, it would be impossible to work the cannon, and therefore they must be removed with the greatest expedition. Accordingly, at the summons of the boatswain, who cries, “Up all hammocks,” every sailor repairs to his own, and having stowed his bedding properly, cords it firmly with a lashing or line provided for that purpose, and carries it to the quarter-deck, poop, forecastle, or whatever other place is most convenient, . As each side of the quarter-deck and poop is furnished with a double net-work, supported by iron cranes fixed immediately above the gunwale or top of the ship's side, the hammocks thus corded are firmly stowed by the quarter masters between the two parts of the netting, so as to form an excellent barrier. The tops, waist, and forecastle, are then fenced in the same manner. By thus disposing of the hammocks, a double advantage is obtained : the batteries of cannon are immediately cleared of an incumbrance, and the hammocks are converted into a sort of parapet to prevent the execution of small shot on the quarter deck, tops, and fore- castle. The hammocks, &c. are not unfrequently thrown over- board at once, when there is no time to stow them away. During the performance of these offices below, the boat- swain and mates are employed in securing the sails and yards, to prevent them from tumbling down when the ship is cannon- aded, as she might thereby be disabled and rendered inca- pable of attack, retreat, or pursuit. . The yards are likewise secured by strong chains or ropes, in addition to those by which they are usually suspended. The boatswain also pro- vides the necessary materials to repair the rigging, wherever it may be damaged by the shot of the enemy; and to supply whatever parts of it may be entirely destroyed. The carpenter and his crew, in the mean time, prepare their shot plugs and mauls to close up any dangerous breaches that may be made near the surface of the water, and provide the iron work necessary to refit the chain pumps, in case their machinery should be injured in the engagement. The gunner, with his mates and quarter-gunners, are busied in examining the can- non of the different batteries, to see that their charges are thoroughly dry and fit for execution: to have every thing ready for furnishing the great guns and small arms with powder, as soon as the action begins: and to keep a sufficient number of cartridges continually filled, to supply the place of those ex- pended in battle. The master and his mates are attentive to have the sails properly trimmed, according to the situation of the ship, and to reduce or multiply them, as occasion requires, with all possible expedition. The lieutenants visit the dif- ferent decks, to see that they are effectually cleared of all incumbrance, so that nothing may retard the execution of the artillery, and to enjoin the other officers to diligence and alert- ness in making the necessary dispositions for the expected engagement, so that every thing may be in readiness at a moment’s warning. When the hostile ships have approached each other to a competent distance, the drums beat to arms, and the boatswain and his mates pipe “All hands to quarters”, at every hatch- way. The persons appointed to manage the great guns imme- diately repair to their respective stations; and crows, hand- spikes, rammers, sponges, powder-horns, matches, train- tackles, &c. are placed in order by the side of every cannon. The hatches are laid, to prevent any one from escaping into the lower apartments. The marines are drawn up in rank and file on the quarter deck, poop, and forecastle. The lashings of the great guns are let loose, and the tompions withdrawn: the whole artillery above and below is run out at the ports, and levelled to the point-blank range, ready for firing. When these necessary preparations are finished, and the officers and crew are all ready at their respective stations, to obey every occasional order, the commencement of the action is determined by the mutual distance and situation of the adverse ships, or by the signal from the commander in chief of the fleet or squadron. The cannon being levelled in parallel rows, projecting from the ship's side, the most natural order of battle is evidently to range the ships abreast of each other, especially if the engagement is general. The most convenient distance is probably within the point-blank range of a mus- quet, so that all the artillery may do effectual execution. The combat usually begins by a vigorous cannonade, accom- panied by the united efforts of all the swivel guns and small arms. As the method of firing platoons, volleys, or broadsides of cannon at once is generally found injurious in the sea ser- vice, it should seldom be attempted, unless in the battering of a fortification; for the sides and decks of the ship, although sufficiently strong for all the purposes of war, would be too much shaken by so violent an explosion and recoil. Instead thereof, the general practice on this occasion throughout the ship is to load, fire, and sponge the guns with all possible expedition, yet without confusion or precipitation. The cap- tain of each gun is particularly enjoined to fire only when the piece is properly directed to its object, that the shot may not be fruitlessly expended. The lieutenants who command the different batteries, traverse the deck, to see that the battle is prosecuted with vigour, and to exhort and animate the men in their duty. The midshipmen second these injunctions, and give assistance, where it is required, at the guns committed to their charge. The gunner takes care that all the artillery is sufficiently supplied with powder, and that the cartridges are carefully conveyed along the decks in covered boxes. : The havoc produced by a continuation of this mutual assault, as at the Nile, Trafalgar, &c. can be more easily imagined than described; battering, penetrating, and splintering the sides and decks; shattering or dismounting the cannon; mangling 3 Y 266 E N G E N G DICTion ARY OF MECHANICAL SCIENCE. and destroying the rigging; cutting asunder or carrying away the masts and yards; piercing and tearing the sails, 39 as to render them useless; and wounding, disabling, or killing the ship's company. The comparative vigour and resolution of the assailants to effect these dreadful consequences, generally determine their success or defeat; but sometimes the fate of the combat may be decided by some unforeseen incident, which may be as fortunate for the one as fatal to the other. * > The ship that is defeated acknowledges the victory by strik- ing her colours, and is immediately taken possession of by the conqueror, who secures her officers and crew as prisoners II] his own ship, and invests two principal officers with the com- mand of the prize till a captain is appointed by the commander in chief. . - - When the engagement is concluded, the men begin the re- pair, or refitting, for the purposes of navigation. . Accordingly, the cannon are secured by their breechings and tackles, with all convenient expedition. Whatever sails have been rendered unserviceable are unbent, and the wounded masts and yards struck upon the deck, and repaired, or replaced by others; the standing rigging is knotted, and the running, rigging spliced, wherever this is necessary. Proper sails are bent in the room of those which have been removed as useless. The carpenter and his crew are employed in repairing the breaches made in the ship's hull, by shot-plugs, pieces of plank, and sheet lead. The gunner and his assistants are busied in replenishing the allotted number of charged cartridges, to supply the place of those which have been expended, and in refitting whatever furniture of the cannon may have been damaged by the late action. Such are the usual consequences and process of an engage- ment between two ships of war, which may be considered as an epitome of a general battle between fleets or squadrons. The latter, however, involves a greater variety of incidents, and necessarily requires more comprehensive skill and judg- ment in the commanding officer. - When the commander in chief, or admiral of a naval arma- ment, has discovered an enemy’s fleet, his principal concern is usually to approach it, and endeavour to come to action as soon as possible. Every inferior consideration must be sacri- ficed to this important object, and every rule of action should tend to hasten and prepare for so material an event. The state of the wind, and the situation of his adversary, will, in some measure, dictate the conduct necessary to be pursued with regard to the disposition of his ships on this occasion. To facilitate the execution of the admiral's orders, the whole fleet is ranged into three squadrons, each of which is classed into three divisions, under the command of different officers. iłefore the action begins, the adverse ſleets are commonly drawn up in two lines, parallel to each other and close hauled. the several divisions separate from the columns, in which they were disposed in the usual order of sailing, and every ship. crowds into its station in the wake of the next a-head : a pro- per distance from each other (which is generally about fifty fathoms) being regularly observed from the van to the rear. The admiral, however, will occasionally contract or extend his line, so as to conform to the length of that of his adversary, whose neglect, or inferior skill in this respect, he will naturally convert to his own advantage, as well as to prevent his own line from being doubled upon; a circumstance which might cause great confusion among his van and rear. When the adverse fleets approach each other, the courses are commonly hauled up in the brails, and the top-gallant-sails and stay-sails furled. The movement of each ship is chiefly regu- lated by the main and fore top-sails and the jibs; the mizen- top-sail being reserved to hasten or retard the course of the ship, and, in fine, by filling or backing, hoisting or lowering it, to determine her velocity. The frigates, tenders, and fire- ships, being also hauled upon a wind, lie at some distance, ready to execute the admiral’s orders or those of his second's, leaving the line of battle between them and the enemy. If there are any transports or storeships attendant on the fleet, these are disposed at a still farther distance from the scene of action. If the fleet is superior in number to that of the enemy, the admiral usually selects a body of reserve from the different squadrons, which will be always of use to cover the fire-ships, bomb-vessels, &c. and may fall into the line, in any case of necessity: these also are stationed at a convenient distance from the line, and should evidently be opposite to the weakest parts thereof. + - Order and discipline give additional strength and activity to a fleet. If thus a double advantage is acquired by every fleet, it is certainly more favourable to the inferior, which may there- by change its disposition with greater facility and despatch than one more numerous, yet without being separated. When courage is equal to both, good order is then the only resource of the smaller number. Hence we may infer, that a smaller squadron of ships of war, whose officers are perfectly disci- plined in working their ships, may, by its superior dexterity, vanquish a more powerful one, even at the commencement of the engagement; because the latter being less expert in the order of battle, will, by its separation, suffer many of the ships to remain useless, or not sufficiently near to protect each other. Thus, though the Gauls had the advantage of the Romans in their numbers; the Germans in their stature; the Spaniards in their strength and numbers united; the Africans in their artifice and opulence; the Greeks in their policy and prudence; yet the Romans triumphed over all by their discipline. - The signal for a general engagement is usually displayed when the opposite fleets are sufficiently within the range of point-blank shot, so that they may level the artillery with cer- tainty of execution, which is near enough for a line of battle. The action is begun and carried on throughout the fleet in the manner (as described) between single ships, at which time the admiral carries little sail, observing however to regulate his own motions by those of the enemy. The ships of the line meanwhile keep close in their station, none of which should hesitate to advance in their order, although interrupted by the situation of some ship ahead which has negligently fallen astern of her situation. . Such is now the practice of naval war, that the necessary order of battle, and the fabric of our ships, very seldom permit the assault of boarding unless in single actions. No captain ought therefore to abandon his station in the line, under any pretence whatsoever, unless his ship is too much disabled to continue the combat. The small quantity of sail carried on this occasion will permit the bulk of the fleet, although some- what impaired, to continue their cannonade a long time with- out quitting the line. No captain should be induced to break the line through a false ambition to distinguish himself, or with the hope of achieving any distant enterprise, however flattering the pros- pect may be. He ought to wait the signal of the admiral, or commanding officer; because it is more essential to preserve - the regularity of a close line, which constitutes the principal As soon as the admiral displays the signal for the line of battle, | force of the fleet, than to prosecute a particular action, which, although brilliant in itself, has seldom any material conse- quences, unless his object is to seize a flag-ship, and even this can only be justified by success. - The various exigences of the engagement call forth the skill and resources of the admiral to keep his line as complete as possible, notwithstanding unequal attacks and damage. He must order ships from those in reserve, to supply the place of those which may have been rendered unqualified by the action: he must direct his fire-ships at a convenient time to fall aboard the enemy, and he must detach ships from one part of the line or wing which is stronger, to another which is greatly pressed by superior force, and requires assistance. His vigilance is ever necessary to review the situation of the enemy from van to rear, every motion of whom he should, if possible, anticipate and disappoint. He should, seize the favourable moments of occasion, which are rapid in their progress, and never return : an opportunity lost may lose the victory. Far from being disconcerted by any unforeseen incident, however distressing it may be, he should endeavour to overcome all difficulties, and make them, if possible, subservient to his designs. His ex- perience and reflection will naturally furnish him with every method of intelligence to discover the state of his different squadrons and divisions. Signals of inquiry and answers— of request and assent—of command and obedience—must be displayed and repeated on this occasion. (See the article E N & E N G 267 DICTIONARY OF MECHANICAL SCIENCE. Signal.) Tenders and boats must also be continually detached between the admiral and the commanders of the several squa-. drons or divisions. When danger presses, he should be fortified by resolution . and presence of mind, because the whole fleet is committed to his charge, and the conduct of his officers may, in a great de- gree, be influenced by his intrepidity and perseverance. In short, his fame or infamy may depend upon the fate of a day. If he proves victorious, he should prosecute that victory as much as possible, by seizing, burning, or otherwise destroying the enemy's ships. If he is defeated, he should endeavour, by every resource his experience can suggest, to save as many of his fleet as possible, by employing his tenders, &c. to take out the wounded, and put fresh men in their places, by towing the disabled ships to a competent distance, and by preventing the execution of the enemy’s fire-ships. In order to retreat with more security, he may judge it expedient to range his fleet into the form of a half-moon or crescent, placing himself in the centre. By this disposition, the enemy’s ships which attempt to fall upon his rear, will at once expose themselves to the fire of the admiral and his seconds, in an advantageous situation: a circumstance which will serve to facilitate the escape of his own ships, and retard the pursuit of those of his adversary. . Should his fleet be too much extended by this arrangement, the wings, or quarters, are easily closed, and the half-moon rendered more complete; in the midst of which may be placed his store-ships, tenders, &c. In retreating, the un- certainty of the weather is to be considered: it may become calm, or the wind may shift in his favour. His schemes may be assisted by the approach of night, or the proximity of land, and he ought rather to run the ships ashore, if practicable, than suffer them to be taken afloat, and thereby transfer additional strength to the enemy. In short, nothing should be neglected that may contribute to the preservation of his fleet, or prevent any part of it from falling into the hands of the conqueror. Upon the whole it appears, the real force or superiority of a fleet consists less in the number of vessels and the vivacity of the action, than in good order, dexterity in working the ships, presence of mind, and skilful conduct in the admiral and captains. ENGINE, in Mechanics, a compound machine formed of one or more of the mechanical powers, and in our language implies nearly the same as machine. Commonly the most simple mechanical powers are denominated tools or instruments, the simplest combination of these are called machines, and the more complicated and powerful are denominated engines. ENGINE to let down heavy weights, as stones, timber, &c. when taking down old buildings, &c. as in the following figure. Tº Erect a frame of wood, or set up a gin close to the wall, and let the pulley P be firmly attached to the frame. A cord passes the convenience of turning it round in any direction. over this pulley, one end of which, C, has a hook, to which the stone, &c. can readily be fastened; the other end, D, carries a vessel which may be filled with water from the reservoir M, on the ground at the bottom of the wall. Then while one man is fixing the stone to the hook at the top of the wall, let another put water into the vessel at the bottom, till it nearly equals the weight of the stone; after which, leaving both to the free opera- tion of gravity, or retarding the motion if requisite, the stone may be thus gradually lowered, while the vessel, a cask for instance, will be raised to the funnel A, into which the water may be poured, and thence conveyed by a wooden or a leather pipe to the reservoir M. Then the vessel D may be suffered to descend, and the hook C will be raised, to be fixed to another stone ; and thus the operation may be repeated as often as is necessary. . - The same method may likewise be adopted in lowering sacks from a high granary, or packages from an upper warehouse. The velocity of the descending weight may be so regulated as to have any proportion to that which gravity imparts to bodies falling freely; thus, if W denote the weight to be lowered, W that W – V f g WTV, or the fraction expressing the ratio of the velocity to that freely imparted by gravity when denoted by unity. Thus, if V = } W, the weight will fall through # of 16%, or about 53 feet in the first seq9nd; if W = #W, the weight will fall through , of 16 k, or about 33 feet in the first second; the friction of the pulley being in both instances disregarded. ENGINEER, a person employed in the construction of the larger kind of engines, or in the application of them to particu- lar purposes. - ENGINEER, is also commonly applied to an officer who is appointed to inspect and contrive any attacks, defences, &c. of a fortified place, or to build or repair them, &c. ENGRAFTING, see GRAFTING. ENGRAILED, in Heraldry, signifies a thing on which the hail has fallen and broken off its edges, leaving them ragged, or with half rounds, or semicircles struck out of their edges. ENGRAVING, is the cutting of lines upon a copperplate, by means of a steel instrument, called a graver, without the use of aqua-fortis. This, the first way of producing copper- plate prints that was practised, is still used in historical sub- jects, portraits, and in finishing landscapes. The necessary tools are, gravers, a scraper, a burnisher, an oil stone, a sand bag, an oil rubber, and good charcoal. The gravers are steel tempered instruments, fitted in a short wooden handle. They are of either a square or lozenge form; the first for cutting broad strokes, the other for fainter and more delicate lines. The scraper, a three-edged tool for scraping off the burr raised by the graver. Burnishers are for rubbing down lines that have been cut too deep, or burnishing out scratches or holes in the copper: they are made of hard steel, well rounded and polished. With the oil stone, the gravers, etching points, &c. are whetted. Upon the sand bag, or cushion, the plate is laid, for The oil rubber and charcoal are used for polishing the plate when necessary. Great care is required to whet the graver nicely, particularly its belly; the two angles of the graver which are to be held next the plate must be laid flat upon the stone, and rubbed steadily, till the belly rises gradually above the plate, so that when you lay the graver flat upon it, you may just per- of the vessel of water, we shall have ceive the light under the point, else it will dig into the copper, and you cannot keep a point, or execute the work with freedom. In order to this, your right arm must be kept close to your side, the forefinger of your left hand placed upon that part of the graver which lies uppermost on the stone. To whet the face, place the flat part of the handle in the hollow of your hand, with the belly of the graver upwards, upon a moderate slope, and rub the extremity, or face, upon the stone, till it has an exceeding sharp point, which you may prove by trial upon your thumb nail. When the graver is too hard, as is usually the case when first bought, and may be known by the frequent breaking of the point, the method of tempering it is as follows:—heat a poker red-hot, and hold the graver upon it, within half an inch of the 268 E N G E N G, DICTIONARY of MechANICAL SCIENCE. point, till the steel changes to a light straw-colour; then put the point into oil to cool, or hold the graver close to the flame of a candle, till it be of the same colour, and cool it in the tallow, but be careful either way not to hold it too long, else it will be too soft; in this case the point, which will then turn blue, must be tempered again. Be not hasty in tempering, for sometimes a little wetting will bring it to a good condition, when it is but a little too hard. - To hold the graver, cut off that part of the handle upon the same lines with its belly, or sharp edge, making that side flat, that it may be no obstruction. Hold the handle in the hollow of your hand, extend your forefinger towards the point, let it rest on the back of the graver, that you may guide it flat and parallel with the plate. Let not your fingers interpose between the plate and the graver, else they will hinder you from carry- ing the graver level with the plate, and from cutting the strokes clearly. To lay the design upon the plate, after you have polished it fine and smooth, heat it till it will melt virgin wax, with which rub it thinly and equally over, and let it cool. Then, with a black- lead pencil, draw on paper the design which you mean to engrave, lay it upon the plate, with its pencilled side upon the wax, then press it close, and with a burnisher go over every part of the design, and when you take off the paper, you will find every line which you drew with the black-lead pencil upon the waxed plate, as if it had been drawn; then with a sharp- pointed tool trace all your design through the wax upon the plate, and you may then take off the wax, and proceed to engrave. The table, or board you work at, should be firm and steady ; your plate should rest upon the sand bag; and holding the graver as above directed, proceed according to the following rules:–For straight strokes, hold your plate firm upon the sand bag with your left hand, move your right hand forwards, lean- ing lighter where the stroke should be fine, and harder where - you would have it broader; but for circular lines, hold the graver steadfast, and move your hand or the plate as you see convenient. Learn also to carry your hand with such dex- terity, that you may finish your stroke as finely as you began it; if you are to make one part deeper or blacker than another, do it by degrees; and that you may do it with exactness, take care that your strokes be neither too close nor too wide. Scrape off the roughness in the course of your work, but do not scratch the plate ; and to see how your work goes on, rub the plate with oil rubber, and wipe it clean. The glare of the fresh-cut copper will thus be taken off, and you will see to better advantage what you have been doing. Mistakes and scratches are rubbed out with the burnisher, the part levelled with the scraper, and the work proceeded in as formerly. In shading up your work, commence with the fainter lines, and finish with deeper. The dry-point executes the lightest parts of the work, as the water, sky, fine draperies, &c. To prevent too much light, a sash made of transparent paper should be placed between your work and the light, which will greatly assist your eyes when the sun shines fiercely. Engraving on Wood, Glass, &c.—Engraving on wood is a pro- cess exactly the reverse to engraving on copper. In copper, the strokes to be printed are sunk or cut into the copper, and a rolling press is used for printing it; in engravings on wood, on the contrary, all the wood is cut away, except the lines to be printed, which are left standing. A wood cut is a type, and the mode of printing is the same as that used in letter-press. Box- wood, planed quite smooth, is used for this purpose. The design is then drawn upon the wood itself with a black-lead pencil ; all the wood is then cut away with gravers and other tools, except the lines that are drawn. Or, the design is some- times drawn upon paper, and pasted upon the wood, which is cut as before. This art is of considerable difficulty; there are now many who practise it, but few who have attained excellence ; Bewick, Branston, Hughes, and some others, cut most beau. tifully. It is, however, useful for books, not because the printing of it is cheaper, as has been supposed, than that of copperplates; but because a block for ready reference can be put in where an engraving on copper could not. Yet it can- not be applied equally well to all the purposes to which Cop- perplate engraving is applicable. Etching on Glass.--Glass resists the action of all acids, except the fluoric acid. By this, however, it is corroded as copper is by aqua-fortis; and plates of glass may be engraved in the same manner as copper. There are several methods of performing this. We shall first describe the process of etch- ing by the fluoric acid in the state of gas. Having covered over the glass to be etched with a thin coat of virgin wax, (common bees' wax bleached white,) draw the design upon it, in the same manner as in etching on copper. Take some fluor spar, (Derbyshire spar,) pound it fine, put it into a leaden vessel, and pour some sulphuric acid over it; place the glass with the etched side lowermost over this vessel, two or three inches above. Apply to the leaden vessel a gentle heat, which will cause the acid to act upon the fluor spar, and the gas disen- gaging itself will corrode the glass. When it is sufficiently corroded, the wax may be removed by oil of turpentine. This etching may be also performed by raising a margin of border- ing wax round the glass, as on copper, and pour on the liquid fluoric acid, which acts upon the glass. - A third method of etching on glass is as follows:–Having put the wax on the glass, draw your design upon it: raise a margin all round it. Then put pounded fluor spar with some sulphuric acid, diluted with water, upon the glass. The sul- phuric acid will disengage the fluoric, which being absorbed by the water, will corrode the glass. Beautiful ornaments may thus be etched on glass, and applied to decorate windows, by painting the figure of the ornament on panes of glass with engravers’ stopping varnish, and then exposing the panes to the action of the gas. The gas will corrode all the surface of the glass, except where the varnish has been put, and give it the appearance of ground glass, which may be rendered more or less opaque by lengthening or shortening the process. The parts where the varnish was applied, will continue transparent, and seem extremely bright. It is to be noticed, that when liquid fluoric acid is used, that lines which have been etched vontinue still transparent; but when the gas has been em- ployed, the line is white and opaque, as if cut by a wheel. Engraving on Precious Stones.—In engraving diamonds, the first thing is to cement two rough diamonds to the ends of two sticks, held steadily in the hand, and rub or grind them against each other, till they are brought into form. The powder serves to polish them, which is performed with a mill turning an iron wheel. The diamond is fixed in a brass dish, and applied to the wheel, and covered with diamond dust, mixed with olive- oil, and first one face, then another, is applied to the wheel. Rubies, sapphires, and topazes, are cut and formed on a copper wheel, and polished with tripoli diluted in water. Agates, ame- thysts, emeralds, rubies, and the softer stones, are cut on a leaden wheel, moistened with emery and water, and polished with tripoli, on a pewter wheel. Lapis-lazuli, opal, &c. are polished on a wooden wheel. To fashion and engrave vases of agate, crystal, &c. a lathe is used, on which are the tools, turned by a wheel; and the vessel is held to them to be en- graven, either in relievo or otherwise; the tools being moist- ened, from time to time, with diamond-dust and oil, or emery and water. Engraving on Steel, or Dye-sinking.—This is chiefly used in cutting seals, punches, matrices, and dies for striking coins or medals. The method of engraving with the instruments, &c. is the same for coins as for medals and counters: the only dif- ference is in the relievo, that of coins being less than that of medals, and that of counters less than that of coins. En- gravers' in steel commonly begin with punches, which are in relievo, and serve for making the creux, or cavity, of the matri- ces and dies: though sometimes they begin with the creux, but only when the work is to be cut very shallow. Improvements in Engraving and Copper-plate Printing.—Very extraordinary improvements in the art of producing and multi- plying impressions of engravings, have lately been made by Jacob Perkins, of Philadelphia, who, from his pre-eminent skill, was employed by the American Banks in the fabrication of notes. It is the peculiar merit of Mr. Perkins's notes, that they are capable of exhibiting the highest perfection of the art of engraving; while at the same time every impression, though millions of them may be required, is equal to a proof. His mode of proceeding is as follows: He first causes the subject E N T E. P. A. DICTIONARY OF MECHANICAL SCIENCE. 269 to be engraved on a flat plate of soft steel, which, being duly hardened, is then capable of impressing a similar surface of soft steel in a cylindrical form. The cylinder in its turn being hardened, is then capable of impressing other flat plates of soft steel, or copper-plates; and one cylinder can thus multiply steel or copper plates, in any desirable number, equal in effect and delicacy to the first engraving. From these, of course, any number of impressions on paper may be taken, all fac similes of one another; and, if steel plates are used, they are all equal to proofs; or, if copper, they may be renewed as often as they begin to wear. The apparatus for transferring the impressions, as well as for producing endless lines in beautiful scrolls, and for other purposes, are highly creditable to the genius and manufactures of the United States: but Mr. P. has proved his fertility of contrivance, by inventing a machine for copper- plate printing, by which he is enabled, with 36 plates and the labour of four men, to produce 180 impressions in a minute, or 60,000 in a day. This artist now carries on his business in Fleet-street, London. * ENNEADECATERIS, in Chronology, a cycle or period of 19 solar or lunar years. ENNEANDICA, in Botany, the name of the 9th class in Linnaeus’ sexual system, consisting of such plants as have Thermaphrodite flowers, with nine stamina, or small organs. ENSIGN, a large flag or banner, hoisted on a long pole, erected over the stern, and called the ensign-staff; the ensign is used to distinguish the ships of different nations from each other, as also to characterize the different squadrons of the navy: it was formerly written ANCIENT. ENTABLATURE, or ENTABLEMENT, in Architecture, is that part of an order of a column over the capital, and comprehends, It is used sometimes to denote the last row of stones on the top of the wall of a build- the architrave, frieze, and cornicle. ing, on which the timber and covering rest. and limited to certain conditions prescribed by the donor or granter. of three-deckers, to serve as doors for persons going in or out of the ship. Entering Ropes, or Side Ropes, three ropes hang- ing from the upper part of the ship's side, or from the entering ports, on the right, left, and middle of the steps: ENTOMOLOGY, that part of Zöology which treats exclu- sively of insects. Linnaeus has divided insects into seven orders. The sexes of insects are commonly two, male and female. Neuters are to be met with among those insects which live in swarms, such as ants, bees, &e. The majority of insects are observed to be annual, finishing the whole term of their lives in the space of a year or less, and many do not live half that time; nay, there are some which do not survive many hours; but this latter period is to be understood only of the animals when in their complete or ultimate form, for the larvae of such as are of this short duration have in reality lived a very long time under water, of which they are natives; and it is observed, that water insects, in general, are of longer dura- tion than land insects. & Insects are distinguished from other animals by their being furnished with never fewer than six feet, and sometimes with many more; by their breathing, by spiracles or breathing-holes, situated at certain distances along each side of the body; and lastly, by the head being furnished with a pair of antennae, or jointed horns, which are extremely various in the different tribes. The first state in which the generality of insects appear, is that of an egg. From this is hatched the animal in its second state, when it is improperly called the caterpillar. The insect, in this state, is the larva or larve, a mask or disguise of the animal in its future form. The larve differs in its appearance, according to the tribe to which it belongs. When the time arrives for the larve to change into its next state of chrysalis, or pupa, it ceases to feed, and having, placed itself in some quiet situation for the purpose, lies still for several hours; and then by a laborious effort, frequently repeated, divests itself of its external skin, or larve-coat, and immediately appears in the very different form of a pupa. The Linnaean term pupa was given, from the indistinct resemblance which many insects bear in this state to a doll, or a child when swathed up accord- ing to the old fashion. The pupa emerges at length the com- plete insect, in its perfect or ultimate form, from which it can never after change, nor can it receive any further increase of growth. . This last or perfect state is termed the imago. Some insects undergo a change of shape, but are hatched complete in all their parts from the egg, and only cast their skin from time to time, during their growth, till they acquire the full size of their species. The mouth in some tribes is formed for gnawing the food, and operates by a pair of strong horny jaws, moving laterally, as in the beetle tribe; while in others it is formed for suction, and consists of a sort of tube. In the butterfly and moth tribe, it consists of a double tube, which, when at rest, is rolled into a spiral form, and when in use, extended at full length. The eyes differ in the different tribes; the greater number of insects are furnished with eyes apparently two in number, and situated on each side the head. The outward surface of the coats of these eyes may be eom- pared to so many convex lenses or glasses. The head of the common dragon-fly is furnished with 25,000 of these lenses : In spiders, the eyes are from six to eight in number; of a simple Structure, and placed at a considerable distance from each other. The muscles, or organs constituting the several portions of the flesh in insects, are more numerous than in the larger animals, and extremely irritable. In the human body, the muscles scarcely exceed 500, in a large caterpillar more than 4000 have been discovered. The power of the muscles is also much greater than in animals. A flea is capable of springing 200 times its own length; whereas the jerboe or kangaroo, in their most powerful leaps, fall very short of the same propor- tional distance. - * . The orders of insects are, 1. Coleoptera, which have crusta- | ceous cases covering their wings, and which, when closed, form ENTAIL, in Law, is a fee- estate entailed, that is, abridged a longitudinal division along the middle of the back, as in the cock-chafer; 2. Hemiptera, which have four wings, the upper | ones partly crustaceous and partly membranaceous, and being ENTERING Ports, ports cut down on the middle gun-deck Crossed over the back, or incumbent on each other, as the cock- roach ; 3. Lepidoptera, insects with four wings, covered with fine scales and powder, as the butterfly, moth; 4. Neuroptera, having four membranous and semi-transparent wings, veined like network, and the tail with a sting, as the dragon fly; 5. Hymenoptera, insects which have four membranaceous and semi- transparent wings veined like network, and the tail armed with a sting, as in the wasp and bee; 6. Diptera insects have only two wings, as the common house-flies; 7. Aptera insects have no wings, as the spiders. ENTRANCE, a name frequently given to the foremost part of the ship under the surface of the sea. ENTREPAS, in the Manege, the broken pace of a horse, resembling an amble, being neither walk nor trot, and proceeds from the animal having no reins or back, and going upon its shoulders. In general, this is the gait of all horses whose limbs are spoiled. ENTROCHUS, in Natural History, a genus of extraneous fossils, known by the popular name of St. Cuthbert's beads, usually found in limestone, and of all sizes, from a pin's head to a finger's length. - ENTRY, WRIt of, is a writ directed to the sheriff, requiring him to command the tenant of the land, that he render to the demandant the premises in question, or appear in court on such a day, and shew why he has not done it. - ENUMERATION, the act of numbering or counting. ENVELOPE, in Fortification, a work of earth sometimes in form of a simple parapet, and yet at others like a small ram- part, with a parapet : it is raised sometimes on the ditch, and sometimes beyond it. ENVOY, a person deputed to negotiate some affair with any foreign prince or state. Those sent from the courts of France, Britain, &c. to any petty prince of Germany, the republics of Venice, Genoa, &c. go in quality of envoys, not ambassadors; and such a character only do those persons bear, who go from any of the principal courts of Europe to another, when the affair they go upon is not very solemn or important. EPACTS, (from straya, induco, intercalo,) in Chronology, the excesses of the solar month above the lunar synodical month, 3 Z 270 E P I E. P. H. DICTIONARY OF MECHANICAL SCIENCE. and of the solar year above the lunar year of twelve synodical months; or of several solar months above as many synodical months, and several solar years above as many dozen of syno- dical months. The epacts then are either annual or menstrual. Menstrual EPActs, are the excesses of the civil or calendar month above the lunar month. Suppose, e.g. it were new moon on the first day of January; since the lunar month is 29' 12, 44; 3", and the month of January contains 31 days, the menstrual epäct is 1d 11° 15'57". 3. Annual EPActs, are the excesses of the Solar year above the lunar. Hence, as the Julian solar year is 365' 6", and, the Julian lunar year 354, 8h 48' 38", the annual epact will be iod 21h 11, 22, that is, nearly 11 days. Consequently, the epact of two years is 22 days; of three years, 33 days; or rather thirty, since 30 days make an embolismic, or intercalary month. Thus the epact of four years is 14 days, and so of the rest; and thus every 19th year the epact becomes 30 or 0; consequently the 20th year, the epact is 11 again; and so the cycle of epacts expires with the golden number, or lunar cycle of 19 years begins with the same ; these are Julian epacts: the Gregorian depend upon the same principles, accounting only for the difference of the respective years. - As the new moons are the same, that is, as they fall on the same day every 19 years, so the difference between the lunar and solar years is the same every 19 years. And because the said difference is always to be added to the lunar year, in order to adjust or make it equal to the solar year, therefore the said difference respectively belonging to each year of the moon's cycle, is called the epact of the said year, that is, the number to be added to the same year, to make it equal to the solar year. e Rule to find the Gregorian Epact.—The difference between the Julian and "Gregorian years being equal to the difference between the solar and lunar year, or 11 days; therefore, the Gregorian Epact for any year is the same with the Julian Epact for the preceding year; and hence the Gregorian Epact will be found by subtracting 1 from the golden number; multiplying the remainder by 1i, and rejecting the 30's. This rule, will serve till the year 1900, but after that year the Gregorian Epact will be found by this rule: divide the centuries of the given year by 4, multiply the remainder by 17; then to this product add 43 times the quotient, and also the number 86, and divide the whole sum by 25, reserving the quotient: next multiply the golden number by 11, and from the product subtract the reserved quotient, so shall the remainder, after rejecting all the 30's contained in it, be the epact sought. The following table contains the golden numbers, with their corresponding epacts, till the year 1900. . TABLe of Gregorian Epacts. Nº. Epacts. Nº. Epacts. Nº. Epacts. T. O VIII. 17 XV. 4 II. 11 IX. 28 XVI. 15 III. 22 |X. 9 |XVII. 26 IV. 3 XI. 20 || XVI II. 7 V. 14 YII. I XIX. | 8 VI. 25 XIII. 12 I. , 0 VII. 6 | |XIV. 23 EPHA, or EPHAH, in Jewish antiquity, a dry measure con- taining about a bushel. EPHEMERA, the Day-Fly, or May-Fly, a genus of insects belonging to the order of neuroptera. There are eleven species. These flies take their name of May-fly from the shortness of their life. Some live several days, others do not take flight till the setting of the sun, and live not to see his rising. Some exist an hour, others half that time. EPHEMERIDES, in Astronomy, tables calculated by astro- nomers, shewing the present state of the heavens for every day at noon; that is, the places wherein all the planets are found at that time. It is from these tables that the eclipses, conjunc- tions, and aspects of the planets are determined, horoscopes or celestial schemes constructed, &c. The astronomers of most nations publish ephemerides; of these the most celebrated are, the Ephemerides of Bologna; the Nautical Almanac, pub- lished in England; and the Connoissance des Temps, pub- lished in France. . - - EPHEMERIS, a Nautical Almanack. - EPICUREANS, a sect of ancient philosophers who followed the doctrine of Epicurus, a celebrated philosopher of Garge- tium in Attica, about 300 years before Christ. At the early age of 12 years he gave astonishing proofs of genius, which he afterwards improved by visiting Athens, which was then crowded by the followers of Plato, the Cynics, Peripatetics, and the Stoics. Here he established himself, and soon attracted a number of followers by the sweetness and gravity of his manners, and by his social virtues. In his ethics he maintained that the Supreme good of man consists in pleasure, and supreme evil in pain. Nature herself, says he, teaches us this truth; and prompts us from our birth to procure whatever gives us pleasure, and avoid whatever gives us pain. This doctrine, which seemed to open the way to sensuality and dissipation, procured for Epicurus a great number of enemies, particularly amongst the Stoics; but he refuted all the accu- sations of his adversaries by the purity of his morals. His followers were numerous in every age and country; but they soon degenerated from the comparatively pure sentiments of their master, and placed their happiness in gross and sensual pleasures. EPICYCLE, in the ancient Astronomy, was a subordinate orbit or circle, which was supposed to move on the circum- ference of a larger one, called the different ; by means of which one motion, apparently irregular, was resolved into two that were circular and uniform. And when the observed motion was so irregular and complicated as not to be resolved with one epicycle, others were added till a nearer approxima- tion was obtained. This system owed its origin to a prejudice that seems to have been extremely ancient, in favour of circu- lar motion; and the problem that principally engaged the attention of astronomers in those times, was to assign the pro- per proportion of the different and epicycle which should approximate nearest to absolute observation. EPICYCLOID, in Geometry, is a curve generated by a point in one circle, which revolves about another circle, either on the concavity or convexity of its circumference, and thus differs from the common cycloid, which is generated by the revolution of a circle along a right line; though the latter has sometimes been assimilated with the former, by considering the right line as the circumference of a circle whose diameter is infinite. The invention of epicycloids is ascribed to M. Roemer, the celebrated Danish astronomer. EPIDEMIC, in Medicine, denotes those diseases which prevail at particular seasons, attacking many persons at the Sam C tilm €. . EPIDENDRUM, a genus of the diandria order. . EPIGASTRIC REGION, a part, or subdivision of the abdomen. EPIGRAPHE, denotes the inscription of a building, point- ing out the time when, the persons by whom, and the uses for which it was erected. - EPILEPSY, in Medicine, the same with what is usually called the falling sickness, from the patient's falling suddenly on the ground. . EPIPHANY, a Festival, otherwise called the Manifestation of Christ to the Gentiles, observed on the 6th of January, in honour of the appearance of our Saviour to the three magi, or wise men, who came to adore him, and bring him presents. The kings of England and Spain offer gold, frankincense, and myrrh, on epiphany, or twelfth day, in memory of the offerings of the wise men to the infant Jesus. The festival of epiphany is called by the Greeks the Feast of Lights, because our Saviour is said to have been baptized on this day; the baptism is by them called illumination. EPISCOPACY, ecclesiastical government by bishops and other dignitaries, as in the church of England. EPISTILE, in Architecture, the architrave, a massive piece of wood or stone laid immediately over the capital of a column. EPITAPH, a monumental inscription in honour or memory of a person defunct, or an inscription engraven or cut on a E P R E Q U DICTIon ARY of MECHANICAL SCIENCE." tomb, to mark the time of a person's decease, his name, family, and, usually, some eulogium of his virtues, or good qualities. . - EPITHEN, in Pharmacy, a kind of fomentation, or remedy of a spirituous or aromatic composition, applied externally to the region of the heart, the liver, &c. to strengthen and comfort the same, or to correct some intemperature thereof. EPOCHA, or AERA, is a certain fixed point of time, made famous by some remarkable event; from whence, as from a root, the ensuing years are numbered or computed. As there is no astronomical consideration to render one epocha prefer- able to another, their constitution is purely arbitrary, and therefore various epochas have been used at different times, and annong different nations. The Christian Epocha commences on the 25th of December, or the 1st of January. But in those countries which observe the Julian calendar, it commences on the 25th of March. The author of this way of computing from Christ, was Dionysius Exiguus, a Roman abbot, who lived about the beginning of the sixth century. The Epocha of the Creation, according to the Jewish compu- tation, is the year of the Julian period 953, answering to the year of Christ 3761, and commencing on the 7th of October. Hence, if we subtract 952 from any given year of the Julian period, the remainder is the corresponding year of the Jewish epocha of the creation. The Epocha of the Olympiads, used principally by the Greeks, is famous in ancient history. It took its rise from the Olympic games, which were celebrated at the beginning of every fifth year, near Olympia, a city of Elis, in Peloponnesus. An Olympiad, therefore, was a period of four years; and by these periods the Greeks reckoned their time, the year in which the games were celebrated the first year of the Olympiad. The beginning of the first Olympiad is referred to the year of th Julian period 3931, or 776 years before Christ. - The Epocha of the Building of Rome, was the principal one among the Romans. This epocha is the year of the Julian period 3961, and answers to the year 752 before Christ, com- mencing on the 21st of April. The Dioclesian Epocha, or epocha of the Martyrs, commences in the year of Christ 284, and that of the Julian period 4997. It obtained its name from the great number of Christians who suffered martyrdom in the reign of the emperor Dioclesian. The Epocha of the Hegira is used by the Turks, Arabs, and others who profess the Mahometan faith. " It commences on the 16th of July, in the year of Christ 622, and of the Julian period 5335. The word hegira signifies flight ; the event which gave occasion to this epocha, being Mahomet's flight from Mecca. The magistrates of that city, finding that his imposture tended to disturb the public peace, were determined to cut off the author of it, to prevent the further spreading of the mischief. But Mahomet, having timely notice of their design, fled by night to Medina, another city of Arabia, in the year of our Lord above mentioned; and this is the principal aera from which the Mahometans compute their time. Dionysius began his account from the conception or incarna- tion, usually called the Annunciation, or Lady Day, which method obtained in the dominions of Great Britain till the year 1752, before which time the Dionysian was the same as the English epoch; but in that year the Gregorian calendar having been admitted by act of parliament, we now reckon from the 1st of January, as in the other parts of Europe, except in the court of Rome, where the epoch of the incarnation still obtains for the date of their bulls. The true birth of Christ was four years earlier than is reckoned in the common date, which cor- responds to 4709 of the Julian epoch. - EPROUVETTE, the name of an instrument for ascertain- ing the strength of fired gunpowder, or of comparing the strength of different kinds of gunpowder. One of the best for the proof of powder in artillery, is that contrived by Dr. Hutton. It consists of a small brass gun, about 23 feet long, suspended by a metallic stem or rod, turning by an axis on a firm and strong frame, by means of which the piece oscillates in a circular arch. A little below the axis, the stem divides into two branches, reaching down to the gun, to which the lower ends of the branches are fixed, the one near the muzzle, the other near the breech of the piece. The upper end of the stem is firmly attached to the axis, which turns very freely by its extremities in the sockets of the supporting frame, by which means the gun and stem vibrate together in a vertical plane, with a very small degree of friction. The piece is charged with a small quantity of powder (usually about two ounces) without any ball, and then fired; by the force of the explosion, the piece is made to recoil or vibrate, describing an arch or angle, which will be greater or less, according to the quantity or strength of the powder. - - To measure the quantity of recoil, and consequently the strength of the powder, a circular brazen or silvered arch of a convenient extent, and of a radius equal to its distance below the axis, is fixed against the descending two branches of the stem, and graduated into divisions, according to the purpose required to be answered by the machine, viz. 1. Into equal parts, or degrees, for the purpose of determining the angle actually described in the vibration, 2. Into unequal paris, according to the chords, being in fact 100 times the double sines of the half angles, and running up to 100, as equivalent to 90 degrees; these serve to compare the velocities given by the powder. 3. Into equal parts, according to the versed sines; they are, in truth, 100 times the versed sines of our common tables, 1613 corresponding with 90 degrees, and these serve to compare the forces. The divisions on these scales are read off, that is, marked out, by an index, which is carried on the arch during the osciliation, and then stopping there, shews the actual extent of the vibration. Dr. Gregory has found, upon several trials, that two ounces of powder give 36 on the chords, or 21° on the arc. Ramsden’s eprouvette is a gun that recoils in a direction parallel to itself, instead of vibrating as a pendulum. - . EPSOM SALTS, are sulphate of magnesia. EQUABLE Motion, is that whereby the moveable body proceeds with the same continued velocity, being neither acce- lerated nor retarded. - EQUABLY accelerated or retarded Motion, &c. is when the motion or change is increased or decreased by equal quantities or degrees, in equal times. EQUAL, a term of relation between two or more things of the same magnitude, quantity, or quality, or equals, are those things which may be substituted for each other without any alteration of their quantity. For it is an axiom in geometry, that two things which are equal to the same thing, are also equal to each other. And again, if to or from equals you add or subtract equals, the sum or remainder will be equal. EQUAL Altitudes, in Practical Astronomy, one of the most practicable and certain methods of determining the time, and thus ascertaining the error of a clock or chronometer, is by observing equal altitudes of the sun or of a fixed star. For this purpose, all that is necessary is, to observe the instant the sun or star is at any altitude towards the east, before the meridian passage; and the instant must likewise be marked when the same object attains exactly the same altitude towards the west, after the meridian passage; the mean between the above quantities will be the instant marked by the clock at the moment the sun or star was on the meridian. The preceding operation, however, supposes. that the declination of the object has not varied during the elapsed interval, but this with the sun seldom happens. The observation must, therefore, be corrected by a table, or by a direct calculation. EQUAL Angles, are those whose containing lines are inclined alike to each other, or which are measured by similar arcs of their circles. EQUAL Arithmetical Ratios, are those wherein the difference of the two less terms is equal to the difference of the two greater. EQUAL Curvatures, are such as have the same or equal radii of curvature. EQUAL Figures, are those whose areas are equal, whether the figures be similar or not. EQUAL Geometrical Ratios, are those whose least terms are similar aliquot or aliquant parts of the greater. g r EQUAL Solids, are those whose capacities are equal. EQUALITY, in Algebra, is a comparison of two quantities which are in effect equal, though differently expressed or 272 E Q U E Q Uſ DICTIONARY OF MECHANICAL SCIENCE. ! represented; and it is usually denoted by two parallel lines, as – ; thus 4 + 4 = 8; that is, 4 added to 4 is equal to 8. But some writers use the character Cº., and others again x, for expressing equality; but the two lines are now generally adopted. In the solution of a numeral problem, which is to be rendered rational, if there be only one formula, to be equal to a square or other higher power, it is called a simple equality. EQUANIMITY, in Ethics, denotes that even and calm || frame of mind and temper under good or bad fortune, whereby a man appears to be neither puffed up nor overjoyed with prosperity, nor dispirited, soared, nor rendered uneasy by adversity. - - - EQUATED Bodies, on the trumter Scale, is the name of two lines, which relates to the comparison of the sphere and the regular bodies; they are, however, seldom given on modern scales. - - EQUATION, in Algebra, is any expression in which two quantities differently represented are put equal to each other, by means of the sign = placed between them; thus 7 a z + 3 a. = b, 5 y” + 3 y — a = 0, 72° -- 3 a.” – 11 = Q, &c. are equations, and these receive different names, according to the various ci tances of the powers, relations, and combina- Warious circumstanc tne p 3. y | three-fifths of the sum shall be 66? - - tions of the unknown quantities which enter into them. A Literal EQUAtion, is that in which all the quantities, both known and unknown, are expressed by letters, as a 2% + ba E c. A Numeral Equation, is that in which the co-efficients of the unknown quantity and absolute terms are given numbers, as 52.2 + 7a: = 16, 2% — I a a - 1 = 0,. &c. A Simple Equation, is that in which the unknown quantity enters only in the first degree, as 7a: = 35, a c + b x = c, 3 a a -i- 5b w = 119, &c.; and these are always better ex- pressed by putting all the co-efficients under a parenthesis, with the unknown quantity outside, thus (a + b) a = c, (3 a + 5 b) a = 119, &c. A Quadratic EQUATION, is that which the unknown quantity . enters into the second degree, as a 2° E b, a r" + ba E c, &c. Note. When only the second power enters, as a cº = b, it is called a Simple Quadratic ; and when the second and first both occur in the same equation, it is called an Adfected Quadratic ; ‘such are the equations-a a.” + b a' = c, a " + a = b ar, &c. A. Cubic Equation, is that in which the third power of the unknown quantity enters, as a:* + a r? -- ba: = c, acº -- a r = b, a cº = e, &c. The latter of which is called a Simple Cubic. * A Biquadratic EQUATION, is that in which the fourth power of the unknown quantity enters, as a z* + b x* + c ac” + da: = e ; and when only the fourth power enters, it is called a Simple Biquadratic. Reduction of EQUATIONs, is of two kinds, viz. first, the reduc- tion of them from a higher to a lower-dimension; and, second, the reduction of them to some particular form, to prepare them for solution. The former of these cases is more commonly called the Depression of Equations, which see ; and the latter usually consists in exterminating the second term of the equa- tion, this being the most eligible form for solution. Some authors also use the term Reduction of Equations, for what is more usually and properly called the Solution of Equations. Solution of EQUATIONs, is the method of finding their roots, which, however, can only be done in a direct manner, for the first four degrees, viz. in Simple, Quadratic, Cubic, and Biquad- ratic Equations ; and the several methods of procedure, in each of these, is given under the annexed examples. Equations that exceed the fourth degree cannot be solved by any direct rule, (except in a few partial cases, in which there are certain relations either between the roots or co-efficients,) although the subject has been investigated by many of the ablest analysts of Europe. We have, itherefore, no means of. obtaining the roots in those cases, but by approximation. - Questions which involve Equations containing only One unknown Quantity.—Question 1. There are two numbers whose differ- ence is 12, and their sum 20; what are the numbers ? As their difference is 12, the greater number must evidently exceed the less number by 12. Solu. Let z = the less number; then a + 12 will be the greater. But by the equation, the sum of the two numbers is 20; or, the greater + the less number = 20. ‘hy 6, the product increased by 36, and that sum divided Hence, by addition, (a + 12) + 2 - 20. - - That is, 2 a. -- a .. = 20. * therefore, 2a: E 20 – 12 = 8. 8 and º: = 5 = 4 the less No. Hence the greater number = a + 12 = 4 + 12 = 16. Question 2. There are two numbers whose difference is 9, and if three times the greater be added to five times the less, the sum will be 35; what are those two numbers ? Solu. Let w = the less; them a + 9 = the greater number. And 3 times the greater 3 × a + 9 = 3 a + 27. 5 times the less E 5 × 2 9 E 5 a. - But, by the condition of the question, 3 times the greater + 5 times the less number – 35. - - - Hence, by addition, (3a; -- 27) + 5 a. = 35; That is, 8a; + 27 = 35, or 83 – 35 — 27 = 8; 3 = and a + 9 = 1 + 9 = 10 the greater number. Question 3. What number is that, to which if we add 10, 1 = the less number; ..". 2 F Solu. Let x = the number sought, then a + 10 = the ber + 10. 3 Now, Eths of a + 10 = IAUlſil- * -- 3 × a + 10 – 3r-80 5 - - L --> X a + 10 = 6 6 º ... 3 *=mºs--- But, by the question, 5ths of a + 10 E 66. 3a –H 30 5 Multiplying by 5, we have 3 c + 30 = 330; ..". 3a. E 330 – 30 = 300, and a = Hence, by substitution, = 66. 300 º •r -ā-- 100 = the required No. Question 4. What is the number which, being multiplied by 18, the quotient shall be 20? J --> Solu. Let a = the number sought. Then 6 a – the number multiplied by 6. Also 6+ + 36 = the product increased by 36, - 6. 36 And ºr ºn = that sum divided by 18. - 6 ºr . - Hence, by the question, *** - 20. And 62 + 36 = 360, multiplying by or 6 a. E 360 — 36 = 324; 324 *- 6 Question 5. A post is one-fifth in the earth, three-sevenths in water, and 13 feet out of water; what is the length of the Ost 7 Solu. Let a = the length of the post; Then 18, ..". Q - = 54, the number required,’ 5 3 ac Also 7 And 13.: the part of it out of the water; But the part in earth + part in water, -- part out of water - the whole post. 3C 3 - Therefore 5 + *: + 13 E ar. the part of it in the earth; , * - the part of it in the water; 15. - Multiply by 5, then a + *: + 65 = 5 a... . . by 7, and 7a: + 15 a + 455 = 35a, ; - • Or 455 = 352–72–15a E13.x. #. = 35 feet, the length of the post. Question 6. Having paid away one-fourth and one-seventh Hence a = * , u E Q U. 273 DICTIONARY OF MECHANICAL SCIENCE. of my money, I had eighty-five pounds left in my purse ; how much money was in it previously to these disbursements' - 3: 2: Solu. Let z = the money in purse at first; then 4 -H 7 is the money paid away. tº . a ac , º Now, by the question, r = 1 + 7 + 85; multiply by 28, Then 28 a = 7 a -- 4a: + 2380, or 17 ac = 2380; Therefore aſ ºt * = £140, the money at first in my purse. Problems, or Questions, involving quadratic equations, are solved by the same process as that for the solution of those which contain simple equations. But as every quadratic equation contains two values of the unknown quantity, ques- tiºns of this class may admit of a double solution. And as the particular nature of the question must determine whether one or isoth of these values may apply to it, no general rule can be laid down, yet may the processes of solution of problems involving quadratic equations be sufficiently understood by observing the conclusions deduced from the following examples. Example 1. . To find that number to which, if you add 12, and multiply the sum by the number required, the product shall 2 589, bºg. Let z = the number sought; Then (x + 12) w = 589, or a 4- 12* = 589 by the question. Complete the square, or add to each side of the equation the square of half the co-efficient of the second term, and we have a; -- 12a: -- 36 = 625; hence, g-º-º-º- extract the root, and we get r + 6 = M626 F 25; Therefore, r = 25 – 6 = 19, the number sought. Example 2. To divide the number 56 into two such parts, that their product shall be 640. Solu. Let z = one part; then 56 - 2 = the other part; And a x (56 – a = the product of the two parts. Hence, a × (56 — a.) = 640, or 56 a – c’ = 640 by the question, or a - 56* = - 640; hence by completing the square, a "- 56* -H 784 = 784 – 640–144; Therefore, a - 28 = + V 144 = + 12; and, consequently, a = 28 + 12 = 40 or 16. Note. The two values of the unknown quantity are, in this instance, the two parts into which the given number was required to be divided. Example 3. Let the difference of two numbers be 7, and half their product plus 30 be equal to the square of the less number; it is required to find those two numbers: Soli. Let a = the less, then a + 7 = the greater number, And zerº + 30 = half their product plus 30. 2 Hence ze; ) + 30 = x*(square of the less) or *:::: + 30 = z* by the question. Multiply now by 2, and a + 7 a -- 60 = 2 a.º. or, by transposition, c' – 7 c = 60; hence 49 by completing the square a' – 72 + T = 60 + 289 17 + 2 ---- *- - - 7 sº- Consequently, z – 3 = + M 4 - + 17 -- 7 Therefore a = === And a + 7 = 12 + 7, or – 5 +7= 19, or 2 = the greater part. Note. This problem, we see, admits of a double solution; for whether 12 and 19 or — 5 and 2 be taken as the correspond- ing less and greater parts, the conditions of the question are answered by each pair of numbers. Illus. Thus the difference of 12 and 19............ is 7. That of - 5 and 2 . . . . . . . . . . . . is 7. 29. E 12, or — 5 E less part; Then comp. the sqr. and a ”— 12 -- 19 - Half product of 12 and 19 + 30 + (12 + 19). + 30 E 144 = 12' = square of the less. - - - "— 2 : That of — 5 and 2 + 30 = C-3, 3) + 30 = 25 = — 3. E square of the less. , Example 4. To divide the number 30 into two such parts that their product may be equal to eight times their difference. Solu. Let x = the less; then 30 — a = the greater part, And 30 – a – a , or 30 — 22 - their difference. Hence, a x (30 — a y = 8 (30 — 22), by the question, or, which is the same, 30a: — a 2 = 240 – 16 a. Or, by transposition, a.” — 46 a. E – 240. \ Complete the square, and a' — 462 + 529 = 529 – 240 - 289, Therefore, a - 23 = + V 289 = + 17, - Whence, a = 23 + 17 = 40 or 6 = less part. - And 30 — a r 30 – 40 or 30 – 6= — 10 or 24 = greater part. Here the equation gives for the less part 40 and 6; but as 40 cannot possibly be a part of 30, we take 6 for the less part which allows 24 for the greater; and the two numbers 24 and 6 answer the conditions of the question. - Example 5. A merchant bought cloth for £33. 15s, which he sold again at £2.8s. per piece, and gained by the bargain as much as one piece cost him : what did he gain by the bargain? Solu. Let a = the number of pieces. Then 675 = the number of shillings which each piece cost; 3: and 48* = the number of shillings which he sold the whole for. Therefore 482 – 675 = what he gained by the bargain. 675 º But 48 ac – 675 E ---, by the question, 225 225 •. * - G © we e Tā a = −16. by transposition and division. 225, , 50625_225, 50625_65025. Töz-HT021-T6+TO.T.T021; and acº — 225 /65025 + 255 ſº Therefore a - :- E + '+H = -- . , --PF - 32 1024 35 y TO24 - + 255 + 225 – 30 And a = - 32T E 15 or T32. But it is obvious the number required is 15, because the con- ditions of the question are such that there cannot be a negative or fractional number of pieces. Example 6. A and B set off at the same time to a place at the distance of 150 miles from that which they left; A travels 3 miles an hour faster than B, and arrives at his journey’s end 8 hours 20 minutes before him : it is required to find what rate each person travelled per hour. Solu. Let a = the rate per hour at which B travels. Then a + 3 = the rate per hour at which A travels. 150 - And — = the number of hours for which B travels. T 50 º Also Tā = the number of hours for which A travels. . But A arrives 8 hours 20 minutes (84 hours) sooner at his journey’s end than B; - - 150 150 150 25 225 Hence a H-3 + 84 = - ; or T5 - 3 = + But, by reduction, we get a 2 + 3a – 54. And completing the square a' + 3 + . E 54 + }= *. 3 /225 Therefore, a + i = y === #. + 15 — And z = * := * * a + 3 = 9 or — 6 miles an hour for A. A E 6 or — 9 miles an hour for B. 274 E Q U E Q U DICTIONARY OF MECHANICAL SCIENCE. Since this is a question of motion, it is evident that if motion to a place be reckoned positive, motiºn, from the same place must be reckoned negative: But A and B are moving to a given place, therefore the positive numbers 6 and 9 are taken for the respective rates per hour of A and B. º - #xample 6. It is required to divide the number 14 into two such parts that their product shall be 50. Soia. Let z = one part; then 14 – ~ := the other part; Hence, by the question, w x (13 – 2)= 50, or 14a – w” = 60; . Therefore, a 2 – 14 a = – 80, And 2–.14 a 4-49 = — 50 + 49 = – 1, or a – 7 = + v-1 : - Therefore, a = 7 -- M – 1. - But both the values of z are impossible, because the question itself is impracticable. - - Equation of Payments, in Arithmetic, is the finding the time to pay at once several debts due at different times, and bear- ing no interest till after the time of payment, so that no loss shall be sustained by either party. The rule commonly given for this purpose is as follows:–Multiply each sum by the time at which it is due ; then divide the sum of the products by the sum of the payments, and the quotient will be the time required. Thus, for example, A owes B £190, to be paid as follows; viz. £50 at 6 months, £60 at 7 months, and £80 at 10 months, what is the equated time at which the whole ºught to be paid, that no loss may arise either to debtor or creditor? By the rule, 50 × 6 = 300 60 × 7 – 420 80 × 10 c 800 190 ) 1520 (8 months equat. time. 1520 - This rule, however, is founded on a supposition, that the interest of the several debts which are payable before the equated time, from their terms to that time, ought to be equal to the sum of the interests of the debts payable after the equated time, from that time to their terns respectively, which, however, is not correct, as it is only the discount, and not the interest in the latter sums. In most cases, however, that occur in business, the error is so trifling, that the popular rule will probably always be made use of, as being by far the most eligible and expeditious method that we could suggest. jāquation, in Astronomy, is a term used to express the cor- rection or quantity to be added to, or subtracted from, the mean position of a heavenly body, to obtain the true position ; it also, in a more general sense, implies the correction arising from any erroneous supposition whatever. Thus, for instance, the time of noon, as determined by taking equal altitudes of the sun, is first obtained by supposing the sun's declination con- stant during the whole interval, which false supposition is corrected by an appropriate equation. Equation of Time, in Astronomy, denotes the difference be- tween mean and apparent time, or the reduction of the appa- rent unequal time, or motion of the sun or a planet, to equable and mean time, or motion. }. If the earth had only a diurnal motion, without an annual, any given meridian would revolve from the sun to the sun again; in the same space of time as from any star to the same star again, because the sun would never change his place with respect to the stars. But as the earth advances almost a degree eastward in its orbit in the time that it turns eastward round its axis, whatever star passes over the meridian on any day with the sun, will pass over the same meridian on the next day when the sun is almost a degree short of it, that is, 3 minutes 56 seconds sooner. If the year contained only 360 days, as the ecliptic does 360 degrees, the sun's apparent place, so far as his motion is equable, would change a degree every day, and then, the sidereal days would be 4 minutes shorter than the solar. The mean and apparent solar days are never equal, except when the sun's daily motion in right ascension is 59" ; which is nearly the case about the 15th of April, the 15th of June, the 1st of September, and 24th of December, when the equator is 0', or nearly so; and it is at its November, when it is 16' 14". greatest about the 1st of EQUATOR, in Astronomy and Geography, is a great circle of the sphere, equally distant from the two poles of the world. It is called the equator, because when the sun is in this circle the days and nights are equal in all parts of the world. Whence also it is called Equinoctial ; and when drawn on maps and planispheres, it is called the Equinoctial Line, or simply the Line. And since every point of the equator is equally distant from the poles of the world, it follows that the equator divides the sphere into two equal hemispheres; that towards the north pole being called the northern, and the other the southern hemi- sphere. As equal or mean time is estimated by the passage of arcs of the equator over the meridian, it frequently becomes necessary to convert parts of the equator into time, and the converse, which is performed by the following analogy, viz. As 15° : 1 hour : : any arc of the equator : the time it has been in passing. Or, conversely, 1 hour : 15° : : any given time : the arc of the equator.—From this circle are reckoned the latitude of places, both north and south, in degrees of the meridian. - EQUATORIAL, UNIVERSAL, or Portable Observatory, is an instrument intended to answer a number of useful purposes in practical astronomy, independent of any particular obser- vatory. It may be employed in any steady room or place, and it performs most of the useful problems in the science, as represented in the figure. The principal parts of this instrument are, 1. The azimuth or horizontal circle, EF, which represents the horizon of the place, and moves on a long axis Q, called the vertical axis. 2. The equatorial, or hour-circle, representing M N the equator, placed at right angles to the polar axis, AB, or the axis of the earth upon which it moves. 3. The semicircle,D,of declination on which the telescope, PO, is placed, and moving on the axis of declination, or the axis of motion of the lime of collimation. The pins or screws I, G, H, are used to adjust the instru- ment, and place it perfectly level by the spirit levels L., L, which transverse at right angles. The peculiar uses of this equatorial are, 1. To find the meridian by one observation only. For this purpose, elevate the equatorial circle to the co-latitude of the place, and set the declination-semicircle to the sun's declination for the day and hour of the day re- quired; then move the azimuth and hour-circles both at the same time, either in the same or contrary direction, till you bring the centre of the cross hairs in the telescope exactly to cover the centre of the sun; when, that is done, the index of the hour-circle will give the apparent or solar time at the instant of observation ; and thus the time is gained, though the sun be at a distance from the meridian ; then turn the hour-circle till the index points precisely at twelve o’clock, and lower the telescope to the horizon, in order to observe some point there in the centre of the glass, and that point is the meridian mark found by one observation only ; the best time for this operation is three hours before or three hours after twelve at noon. 2. Point the telescope on a star, though not on the meridian, in full day-light. Having elevated the equatorial circle to the co-latitude of the place, and set the declination-semicircle to the star's declination, move the index of the hour-circle till it shall point to the precise time at which the star is then distant from the meridian, found in tables of the right ascension of the stars, and the star will then appear in the glass. Besides these uses peculiar to this instrument, it is also applicable to all the purposes to which the principal astronomical instruments, viz. a transit, a quadrant, and an equal altitude instrument, are applied. - . E Q U E Q U 275 DICTIONARY OF MECHANICAL SCIENCE. EQUERRY, in the British customs, an officer of state, under the master of the horse. There are five equerries, who ride abroad with his majesty; for which purpose they give their attendance monthly, one at a time, and are allowed a table. . - - EQUES Aur ATUs, is used for a knight bachelor, called auratus, q. d. gilt, because anciently none but knights were allowed to beautify their armour, or other habiliments of war, with gold. EQUESTRIAN, a term chiefly used in the phrase equestrian statue, which signifies a person mounted on horseback. EQUIANGULAR, in Geometry, is applied to figures whose angles are all equal ; such are the square, and all regular figures. All equilateral triangles are also equiangular. . An equilateral figure, inscribed in a circle, is always equiangular ; but an equiangular figure, inscribed in a circle, is not always equilateral, except when it has an odd number of sides. If the-number of the sides be even, then they may be either all equal, or else half of them will always be equal to each other, and the other half to each other; the equals being placed alternately. EQUIANGULAR, is also applied to any two figures of the same kind, when each angle of the one is equal to a corresponding angle in the other, whether each figure, separately considered, be an equiangular figure or not ; that is, having all its angles equal to each other. Thus, two triangles are equiangular to each other, if one angle in each be of 30°, a second angle in each of 50°, and the third angle of each equal to 100°. Equiangular triangles, according to the above acceptation of the term, have not their like sides necessarily equal, but proportional to each other; and such triangles are always similar to each other. EQUICRURAL TRIANGLE, is what we more usually call an isosceles triangle. The term is derived from aquus, equal, and crura, legs, equal legs. EQUICULUS, EQUULEUs, or Equus Minor, in Astronomy, a constellation in the northern hemisphere. 'N EQUIDIFFERENT, in Arithmetic, is when, in a series of quantities, there is the same difference between the first and second, as between the second and third, third and fourth, &c. and they are then said to be continually equidifferent; but if, in a series of quantities there be only the same difference between the first and second, as between the third and fourth, fifth and sixth, &c.; then they are said to be discreetly equi- different. Thus 3, 6, 7, and 10, are discreetly equidifferent; and 3, 6, and 9 continually equidifferent. EQUIDISTANT, in Geometry, a term of relation between two things which are every where at the same, or at equal distances, from each other. EQUIDISTANT Ordinates, Method of, is an approximation towards the area of a figure bounded by a right line and curve. Having measured any odd number of equidistant ordinates, put the sum of the first and last = A, the sum of the second, fourth, sixth, &c. = B, the sum of all the others = C, and the common distance of the ordinates = D ; then A+4+2c × D = area nearly. And the same formula is applicable to the mensuration of solids, by taking the sections instead of the ordinates. EQUILATERAL, (from aquus and latus, side,) is applied to those figures whose sides are all equal. Thus, an equilateral triangle is that whose sides are all equal. To find the area of an equilateral triangle, multiply the square of the side by # V 3. EQUILIBRIUM EQUIPOIs ED, in Mechanics, means an equality of forces acting in opposite directions, whereby the body acted upon remains at rest, or in equilibrio, in which state the least additional force being applied, on either side, motion will ensue. A body in motion is also said to be in equi- librio, when the power producing the motion, and the force whereby it is resisted, are so adjusted that the motion may be uniform. EQUIMULTIPLES, the products arising from the multipli- cation of any two or more primitive quantities, by the same number or quantity. Thus, 3 a, 3b). - 7 a., n. ; are equimultiples of a and b, m a., m b - - Equimultiples of any quantities have the same ratio as the quantities themselves; thus, a b : : na : n b ; and a b : : m a ; m b. ~ EQUINOCTIAL, in Astronomy, a great circle of the sphere, under which the equator moves in its diurnal motion. The equinoctial is conceived, by supposing a semidiameter of the sphere produced from a point of the equator, and there, by the rotation of the sphere about its axis, describing a circle on the immoveable surface of the heavens. The poles of this circle are the poles of the world. The sphere is divided by it into two equal parts, the northern and southern. It intersects the horizon of any place in the east and west points; and at the meridian, its elevation above the horizon is equal to the co- latitude of the place. Whenever the sun, in his progress through the ecliptic, comes to this circle, it makes equal days and nights in all parts of the globe; as he then rises due east, and sets due west, which he never does at any other time of the year. And hence the denomination from a quus and mor, because day and night are equal. All the stars under this circle, or that have no declination, rise due east, and set due west. The equinoctial, then, is the circle which the sun describes, or appears to describe, at the time of the equinoxes, that is, when the length of the day is every where equal to that of night, which happens twice a year. From this circle is the declination in the heavens, or latitude of places on the earth, counted in degrees of the meridian. Upon this circle is reck- oned the longitude 180° west, and 180° east; and in all 360°. Hence 19 of longitude answers to 4 of time, 15 to 1' of time, and 1' to 4” of time, &c. The shadows of those who live under this circle are cast to the southward for one half of the year, and to the northward during the other half; and twice in a year, viz. at the equinoxes, the sun at noon casts no shadow, being in their zenith. EQUINoctſAl Colure, is that passing through the equinoctial points. See Colu Re. Equi Noctl AL Dial, is one whose plane is parallel to the equinoctial. The properties or principles of this dial are: 1. The hour lines are all equally distant from one another, quite round the circumference of a circle; and the style is a straight pin, or wire, set up in the centre of the circle, perpen- dicular to the plane of the dial. 2. The sun shines upon the upper part of this dial-plane from the 21st of March to the 23d of September, and upon the under part of the plane the other half of the year. EQUINocti AL Points, are the two points wherein the equator and ecliptic intersect each other; the one, being in the first point of Aries, is called the vernal point; and the other, in the first point of Libra, the autumnal point. Poul Nocti Al Gales, storms which are observed generally to take place about the time of the sun's crossing the equator or equinoctial line, at which time there is equal day and night throughout the world. - EQUINOX, in Astronomy, the time when the sun enters one of the equinoctial points. The equinoxes happen when the sun is in the equinoctial circle ; when of consequence the days are equal to the nights throughout the world, which is the case twice a year, viz. about the 21st of March and the 23d of Sep- tember; the first of which is the vernal, and the second the autumnal equinox. It is found by observation, that the equi- noctial points, and all the other points of the ecliptic, are con- tinually moving backward, or westward ; which retrograde motion of the equinoctial points, is what is called the precession of the equinoxes. See PRECESSION. It appears from the result of calculations, that the path of either of the poles is a circle, the poles of which º: with those of the ecliptic, and that the pole will moveºlong that circle so slowly as to accomplish the whole revolutionſ in about 25,791 years nearly. The diameter of this circle is equal to twice the inclination of the ecliptic to the equator, or about 47 degrees. Now, as the ecliptic is a fixed circle in the heavens, but the equator, which must be equidistant from the poles, moves with the poles, therefore the equator must be constantly changing its intersection with the ecliptic. And from the best observations it appears, that the equator cuts the ecliptic every year 50 seconds 25, more to the westward, than it did the year before; hence the sun's arrival at the equinoctial 276 E S 6) E. R. I DICTIONARY OF MECHANICAL SCIENCE. point precedes its arrival at the same fixed spot of the heavens every year by 20 minutes 23 seconds of time, or by an arc of 50 seconds 25. Thus, by little and by little, these equinoctial points will cut the ecliptic more and more to the westward, till after 25,791 years, they return to the same point precisely. EQUITY, quasi aqualitas, is generally understood in Law, a liberal correction, or qualification of the law, where it is too strict, too confined, or severe, and is sometimes applied where, by the words of a statute, a case does not fall within it, yet being within the mischief, the judges, by an equitable construc- tion, have extended its application to that case. Equity is understood as a correction of the law ; and hence, the court of chancery, and the court of exchequer, act as courts of equity; they are also courts of law. There are some cases which belong, peculiarly, to a court of chancery, as the care of | infants, and appointing guardians to them, so of lunatics and charities, in which the chancellor acts for the king as keeper of his conscience. In other cases, as in the cases of trust, matters of fraud, account, suits for a discovery, matters of accident, and the like, courts of equity act in aid of the courts of law, and give relief where, from the nature of the case, a court of law cannot relieve. Thus, where an agreement is to be per- formed, courts of law can only give damages for the breach, but a court of equity, taking all the circumstances into consi- deration, directs and enjoins a specific performance of it according to good conscience. So, where it apprehends an injury likely to be done, it will interfere to prevent it. EQUITY of Redemption. Upon a mortgage, although the estate upon nonpayment of the money becomes vested in the mortgagee, yet equity considers it only a pledge for the money, and gives the party a right to redeem, which is called his equity of redemption. If the mortgagee is desirous to bar the equity of redemption, he may oblige the mortgager either to pay the money, or be foreclosed of his equity, which is done by proceedings in chancery by bill of foreclosure. EQUUS, the Horse, a genus of the mammalia class, of the order of belluae. - EQUULEUS, EQUICULUs, and EQUUs Minor, the Horse's Head, one of the northern constellations, which represents, ac- cording to the poets, the horse which Mercury gave to Castor, and which he named Celeris. From the imperfect representation of the animal in this constellation, the head only being imagined, it has obtained the name of Equi Sectio. Pegasus, we suspect, being a symbol that perpetuates the first emigration of the Cimri. Can the Little Horse be a chronological symbol of the second irruption of the north-eastern nomadic nations into Egypt somewhere about 2500 years ago?—Boundaries and Contents. North and west by Delphinus, south by Aquarius, east and north by Pegasus; right ascension 316°, declination north 5°. Number of stars, 10. - ERATOSTHENES, a Greek of Cyrene, librarian of Alex- andria, under King Euergetes, son of Ptolemy Philadelphus. He died 194 years before Christ; and was called the Cosmographer, because he was the first who discovered the method of measur- ing the bulk and circumference of the earth. ERICA, Heath, a genus of the monogynia order, in the octandria class of plants, and in the natural method ranking under the 18th order, bicornes. There are upwards of 100 species, four of which are natives of Britain. ERIDANUS, or THE River Po, is a much fabled constel- lation; but we may notice chiefly the story which attributes its celestial honours to the accidental circumstance of Phaeton's tumbling into it when Jove hurled the daring charioteer from the skies. . In its vicinity the sisters of that rash youth were metamorphosed into poplars, and their tears into amber, an article which, however, is found chiefly on the Baltic Prussian shores. If, however, we refer the stream of Orion to the Peluge, the constellation of that name being taken as a type of the diluvian Patriarch,-the River of Aquarius, which Fiscis Australis appears to swallow, may then indicate the recession of the waters from the submerged earth, and their confinement within the bed of the ocean, a fish being the hieroglyphic of the great deep;-or the Eridanus may have allusion to the same catastrophe; for the termination of the stream in the horizon might, to the people of Egypt, indicate its being swallowed up by Typhon, the lower hemisphere, or the ocean. - N The boundaries and contents of this immense constellation, wind from Orion to Cetus, and thence in a serpentine form to the Phoenix. According to the Britannic Catalogue, there are eighty-four stars in Eridanus, viz. one of the 1st magnitude, one of the 2d, eight of the 3d, twenty-one of the 4th, &c. The brilliant called Achernar, of the first magnitude, has 1 ho. 31 mi. 4 sec. right-ascension in Time, or in degrees of the Equa- tor, 22° 46', and 589 8' 35" declination S. ; of course it is never visible in our northern latitudes. It culminates half an hour before the chief star in Aries, or by the following table in astronomical time: - MONTH. CULM. MonTH. CULM. MonTH. CULM. - ho. mi. sec. ho. mi. sec. ho. mi. sec. Jan. 6 43 44 May 22 55 6 Sept. 14 48 34 Feb. 4 31 50 June 20 52 34 Oct. 13 0 46 Mar. 2 43 2 July 18 48 38 || Nov. 11 4 45 April 0 49 36 Augt. 16 44 15 Dec. 9 1 13 The course of the Eridanus is easily traced from Rigel in the foot of Orion, and under the Bull to Cetus, and thence S. E. and S. W., till it is lost in the horizon, or more properly in its termination at the Phoenix. - - ERINACEUS, Hedgehog, a genus of quadrupeds of the order of ferae. ERROR, in Law, signifies an error in pleading, or in the process; and the writ which is brought for remedy thereof, is called a writ of error. - - ERROR, in Astronomy, is the difference between the places of any of the heavenly bodies, as determined by calculation and observation. Thus the error in the lunar tables is the dif- ference between the place of the moon, as given in the tables, and as determined by observation; and this error is marked with the sign + or —, according as it is to be added to or sub- tracted from the tabular result. ERUCTATIONS, in Medicine, the effect of flatulent foods, and the consequent crudities. ERUPTION, in Medicine, a sudden and copious excretion of humours, and the same with exanthema, or breaking out; as the pustules of the plague, small-pox, measles, &c. ERYSIPELAS, in Medicine, an erruption of a fiery or acrid humour which chiefly attacks the face. ESCALADE, in War, a furious attack of a wall or a ram- part; carried on with ladders, to pass the ditch or mount the rampart, without proceeding in form, breaking ground, or carry- ing on regular works to secure the men. ESCAPE, in Law, is where a person arrested gains his liberty before he is delivered by law. Escapes are either in civil or criminal cases; and may be distinguished into volun- tary and negligent; voluntary, where it is with the consent of the keeper; negligent, where it is for want of due care. In civil cases, after the prisoner has been suffered voluntarily to escape, the sheriff can never after retake him, and must answer for the debt, but the plaintiff may retake him at any time. In the case of a negligent escape, the sheriff, upon fresh pursuit, may retake the prisoner, and the sheriff shall be excused if he has him again before any action is brought against himself for the escape. In criminal cases, an escape of a person arrested is an offence against public justice, and the party is punishable by fine and imprisonment. ESCHEAT, in Law, denotes an obstruction of the course of descent, and a consequent determination of the tenure by some unforeseen contingency; in which case, the land naturally re- sults back to the original grantor, or lord of the fee. ESCUTCHEON, in Heraldry, is derived from the French escusson, and that from the Latin scutum, signifying the shield whereon coats of arms are represented. © - Escutcheon, of Pretence, that on which a man carries his wife's coat of arms; being an heiress, and having issue by her. It is placed over the coat of the husband. º Escutcheon, the compartment in the middle of the ship's stern, where her name is written. ESOX, Pike, a genus of fishes of the order abdominales. The common pike is a native of most of the lakes and smaller rivers in Europe, but the largest are those of Lapland, which are sometimes eight feet in length. The largest in this coun- try is said to have weighed thirty-five pounds. The head of the pike is flat; the upper jaw broad, and shorter than the E T. C. E T C 277 DICTIONARY OF MECHANICAL SCIENCE. lower, the teeth are very sharp, and the number, not less than seven hundred, without reckoning those nearest the throat: it is also to be observed, that those which are situated on the jaws are alternately fixed and moveable; the gape is very wide, and the eyes small. The usual colour of this fish is a pale olive-gray, deepest on the back, and marked on the sides by yellowish spots: the abdomen is white, spotted with black. ESPALIERS, rows of trees planted about a garden, and trained up regularly to a lattice of wood-work in a close hedge, for the defence of tender plants. ESPLANADE, in Fortification, the sloping of the parapet of the covered way towards the champaign; the same with glacis. ESPLEES, in Law, the general products which lands yield, or the profit or commodity which is to be taken or made of a thing. - EšquTRE, anciently the person that attended a knight in the time of war, and carried his shield. Those to whom the title of esquire is now of right due, are all noblemen's younger sons; and the eldest sons of such younger sons; the eldest sons of knights, and their eldest sons; the officers of the king’s courts, and of his household ; counsellors at law, justices of the peace, &c., though those latter are only esquires in reputa- tion: besides, a justice of the peace holds this title no longer than he is in commission, in case he is not otherwise qualified to bear it; but a sheriff of a county, who is a superior officer, retains the title of esquire during life, in consequence of the trust once reposed in him ; the heads of some ancient families are esquires by prescription. ESSENCE, in Philosophy, the particular nature of each genus or kind, and that which distinguishes it from all others. ESSENTIAL SALT of LeMons. Four ounces of cream of tartar, and eight ounces of sal acelosellae; well mixed together. ESSOIN, in Law, an excuse for a person summoned to appear and answer to an action, on account of sickness or other just cause of absence. Esso IN Day, the first day of every term, though the fourth day after is also allowed by way of indulgence. ESTATE, in Law, signifies such inheritance, freehold, term for years, tenantcy by statute-merchant, staple, elegit, or the like, as any man has in lands and tenements. Estates are real of lands, tenements, &c., or personal, of goods or chattels; otherwise distinguished into freeholds that descend to the heir, and chattels which go to the executors. * ESTIVAL, belonging to, or continuing for, the summer. ESTOPPEL, in Law, an impediment or bar to an action, which arises from a person’s own act; or where he is forbidden by law to speak against his deed, which he may not do, even to plead the truth. ESTOVERS, in Law, a liberty of taking necessary wood for the use or furniture of a house or farm. ESTRAYS AND WAIFS. Estrays are any valuable beasts, not wild, found within a lordship whose owner is not known; such as are commonly impounded and not claimed. They are then to be proclaimed in the church and two nearest market- towns, on two market-days, and not being claimed by the owner, belong to the king, and now commonly, by grant of the crown, to the lord of the manor, or the liberty.—Waifs are goods which are stolen, and waved, or left by the felon on his being pursued, for fear of being apprehended; and forfeited to the king or lord of the manor. 8 } ESTREAT, in Law, is a true copy or note of some original writing on record. . ETCHING, one species of engraving on copper, the lines being corroded in with aqua fortis, instead of being cut with a graver, which, for many purposes, is superior to engraving; but there are others in which the subjects must be graved, not etched. In general, in engravings on copper executed in the stroke manner, etching and graving are combined; the plate is begun by etching, and finished with the graver. Landscapes, architecture, and machinery, receive most assistance from etching, which is not so applicable to portraits and historical designs, though in these also it has a place. The various instruments and materials used in the art, are— Copper-plates, prepared by the coppersmiths. Etching-points, or needles, of steel, an inch long, fixed in handles of wood about six inches in length, and of the size of a goose-quill. These should be well tempered, and accurately fixed in the centre of the handle. They are brought to an accu- rately conical point, by rubbing upon an oil-stone. : A parallel ruler, for drawing parallel lines, is faced with brass, not to be bruised by accident. Compasses, for describing circles and measuring distances. Aqua fortis, or what is better, spirits of nitre (nitrous acid), to corrode the copper; a process called biting in. This liquid is kept in a bottle with a glass stopper, as its fumes destroy corks. A stopper of wax, or a cork well covered with wax, will serve as a substitute. Bordering-waa, for surrounding the margin of the copper- plate, when the aqua fortis is pouring on, may be bought ready prepared, or made thus: Take one-third of bees-wax to | two-thirds of pitch; melt them in an iron ladle, and pour them, when melted, into water lukewarm; then mould it with your hand till it is thoroughly incorporated, and all the water squeezed out. Form it into rolls of convenient size. Turpentime-varnish, for covering the copper-plate, in any part where you do not wish the aqua fortis to bite, is diluted to a proper consistence with turpentine, and mixed with lamp- black, to be seen better when laid upon the plate. Etching-ground, for covering all over the plate, previous to drawing with the needles, is prepared thus: Take of virgin- wax and asphaltum, each twenty ounces; of black-pitch and Burgundy-pitch, each half an ounce; melt the wax and pitch in a new earthenware glazed pipkin, and add to them, by de- grees, the asphaltum finely powdered. Let the whole boil till such time as a drop of it upon a plate will break when it is cold, or bending it double two or three times between the fingers. The varnish being them boiled enough, is taken from the fire, and cooled a little, and poured into warm water, that it may work the more easily with the hands, into balls for use. The fire must not be too violent, lest the ingredients burn; a slight simmering will be sufficient; that while the asphaltum is putting in, and after it is mixed with them, the ingredients should be stirred with a spatula; the water into which this composition is thrown, should be nearly of the same degree of warmth with the composition, to prevent a kind of cracking, which happens when the water is cold. The varnish ought to be harder in summer than winter; it will become so if it be suffered to boil longer, or a greater proportion of the asphaltum be used. The experiment above mentioned, of the drop suf- fered to cool, will determine the degree of hardness or softness suitable to the season when used. To lay the ground for etching, we clean the copper-plate with fine whiting and a linen rag, to free it from grease; and, as a handle for managing it by when warm, we fix a hand-vice to some part of it where no work is intended to be laid. We then hold the plate over burning paper or a chafing-dish, to heat it, so as to melt the etching-ground, which should be wrapped up in a bit of taffeta, to prevent any dirt, that may happen to be among it, from mixing with what is melted upon the plate. It must be heated just sufficient to melt, not to burn the ground. When a sufficient quantity of the etching- ground has been rubbed on the plate, dab it, or beat it gently, while the plate is hot, with a small dabber made of cottom wrapped in taffety. By this operation, the ground is distributed more equally over the plate, than by any other means. When the plate is thus uniformly and thinly covered with the warnish, it is blackened by smoking it with a wax-taper, thus: Twist together three or four pieces of wax-taper to make a large flame, and while the plate is still warm, hold it with the varnished side downwards, and move the smoky part of the lighted taper over its surface, till it is almost black; but let not the wick touch the warnish, lest it get smeared or stained. In laying the etching-ground, take care that no particles of dust settle upon it, as that would be found troublesome in etching ; the room therefore in which it is laid should be still, and free from dust. The ground being laid, and suffered to cool, the next opera- tion is to transfer the design to the plate. For this purpose a tracing on oiled paper is made from the design to be etched, with pen and ink, having a very small quantity of ox’s gall mixed with it, to make the oiled paper take it; also a piece of thin paper, of the same size, is rubbed over with red chalk, 30. 278 E T C E U D DICTIONARY OF MECHANICAL SCIENCE. powdered, by means of some cotton. Then laying the red chalked paper, with its chalked side next the ground, on the plate, put the tracing over it, and fasten them both together, and to the plate, by a little bit of the bordering wax. When all this is prepared, with a blunt etching needle go gently all over the lines in the tracing, and the chalked paper will be pressed against the ground, and the lines of the tracing trans- ferred to it. The plate is now prepared for drawing through the lines marked upon the ground. The etching-points or needles are now employed, leaning hard or lightly, according to the degree of strength required in the lines. Points of different sizes and forms are also used, to make lines of different thickness, though this is commonly effected by the biting-in with aqua fortis. A margin or border of wax formed all round the plate, holds the aqua fortis when it is poured on. The bordering wax already described, is put into lukewarm water to soften it, and render it easily worked by the hand. When sufficiently pliable, it is drawn into rolls, and put round the edges of the plate, in a meat wall or margin. A spout is formed in one corner, by which afterwards to pour off the aqua fortis. The nitrous acid (spirits of nitre) is now diluted with four or five times as much water, or more (according as you wish the plate to be bit quick or slow,) and poured upon the plate. In a few minutes minute bubbles of air will fill all the lines drawn on the copper. These are removed by a feather; and the plate is every now and then swept, as it is called, or kept free from air bubbles. By the more or less rapid production of these bubbles, you judge of the rapidity with which the acid acts upon the copper. The biting-in of the plate is the most un- certain part of the process, nothing but experience can enable any one to tell when it is bit enough, as the thickness and depth of the line cannot easily be seen till the ground is removed. When you judge, from the time the acid has been on, and the rapidity of the biting, that those lines you wish to be the faintest are deep enough, you pour off the aqua fortis by the spout, wash the plate with water, and dry it, so as not to melt the ground. Those lines not intended to be bit any deeper are now stopped up with turpentine varnish mixed with lamp- black, and laid on with a camel's hair pencil; when this is thoroughly dry, the aqua fortis is poured on again, to bite the other lines that are to be deeper. . This process of stopping out and bitting in is to be repeated as often as lines of different degrees of thickness are to be made. It is necessary also to be careful to stop out, with the varnish, those parts from which the ground may have come off by the action of the acid, else parts will be bit that were not intended. This is called foul-biting. When the biting-in is finished, remove the bordering-wax and the ground, that you may see what success you have had. To take off the bordering-wax, the plate is heated by a piece of lighted paper, which softens the wax in contact with the plate, and it comes off clean. Oil of turpentine is now poured upon the ground, and the plate rubbed with a linen rag, to remove all the ground. Lastly, it is cleaned with whiting. The success of the etching is now known, but it is necessary to get an impression upon paper by a copper-plate printer. This impression is called a proof. If any parts are not bit so deep as were intended, the process is repeated, provided the lines are not too faintly bit. This re-biting is done as follows: melt some of the etching-ground on a spare piece of copper, dab it a little, to get some on the dabber; clean out with whit- ing the lines that are to be re-bit, heat the plate gently, dab it lightly with the dabber, and the parts between the lines will be covered with the ground, but the lines themselves will not be filled up, and consequently will be exposed to the action of the aqua fortis. This delicate process must be performed with great care. The rest of the plate is now varnished over, the bordering-wax put on again, and the biting repeated as at first. Should any part be bit too deep, it is recovered or made fainter, by burnishing the part down, or rubbing it with a piece of charcoal, which will make the lines shallower, and cause them not to print so black. Should any small parts of the lines have missed in the biting, they are cut with the graver, which is also sometimes employed to cross the lines of the etching and give it a more finished effect. Dry-pointing, another method for softening the harsh effects usually apparent in an etching, is done by cutting with the etching-point upon the copper without any ground or varnish. This process does not make a deep line, and is used for cover- ing the light, where delicate tints and soft shadows are wanted. By varying these processes of etching, graving, and dry-point- 'ing, as may be necessary, the plate is worked up to the full effect intended, and then sent to the writing engraver, to grave whatever letters or inscriptions may be required. ETHER, an element, supposed by some philosophers to occupy the upper regions of space, more fine and subtle than air. - * ETHICS, or MoRALITY, the science of morals or duty, which it traces from man's nature and condition, and proves to ter- minate in his happiness; or, in other words, it is the know- i. of our duty and felicity, or the art of being virtuous and appy. EUCLID, a celebrated mathematician of Alexandria, who flourished before Christ 300 years. He immortalized his name by his books on geometry, in which he digested all the propo- sitions of eminent geometricians who had preceded him, as Thales, Pythagoras, and others. King Ptolemy became one of his pupils, and his school became so famous, that Alexandria º for many ages the great university for mathematical studies. - EULER, Leonard, one of the most celebrated analysts of the last century, was born at Basil in the year 1707, and very early discovered great talents as well in the study of the Greek and Latin languages as in the various branches of the mathe- matical and philosophical sciences. The natural genius of Euler was also much assisted by an astonishing retentive memory, which enabled him, it is said, to repeat the whole of the AEneid of Virgil from beginning to end; and to point out to his hearers the first and last line of every page in the edition that he had accustomed himself to read. It is also farther stated, that he could remember the first six powers of all num- bers under 100. Besides being foreign member of the Academy of Sciences of Paris, Euler was member of the Imperial Aca- demy of Petersburgh, ancient director of the Academy of Berlin, and fellow of the Royal Society of London. He died at Petersburgh, where he had spent a great part of his life, on the 7th of September, 1783, in the 76th year of his age. EUDIOMETRY, the science of determining the purity of atmospheric air, by measuring the proportion of oxygen (on which its respirable property depends) in a given quantity of it; whence the tests or instruments employed in this science are denominated eudiometers. EUDOXUS, of Cnidus, a city of Caria in Asia Minor, a celebrated astronomer and geometer, who flourished about 370 years before Christ. He composed “Elements of Geome- try,” to which work, according to the account of Proclus, Euclid was much indebted for many of his propositions; indeed, some writers have attributed to him the whole of Euclid's “Elements.” Eudoxus is said to have died in the year before Christ 352, in the 53d year of his age. EUDIOMETER. An instrument for ascertaining the purity of air, or rather the quantity of oxygen contained in any given bulk of elastic fluid. Dr. Priestley’s discovery of the great readiness with which nitrous gas combines with º oxygen, and is precipitated in the form of nitric acid, was the basis upon which he constructed the first instrument of this kind. His method was extremely simple: a glass vessel, containing an ounce by measure, was filled with the air to be examined, which was transferred from it to a jar of an inch and a half diameter, inverted in water; an equal measure of fresh nitrous gas was added to it; and the mixture was allowed to stand two minutes. If the absorption were very considerable, more nitrous gas was added, till all the oxygen appeared to be absorbed. The residual gas was then transferred into a glass tube, two feet long, and one-third of an inch wide, graduated to tenths and hundredths of an ounce measure; and thus the quantity of oxygen absorbed was measured by the diminution that had taken place. The burning of hydrogen gas, and of phosphorus, has also been employed. The same object has also been effected by observing the quantity of oxygen absorbed by a solution of sulphuret of potash. s - -- - - i § - i s : -- * 3:33 lºs º: - - - - - - - N - - - - º - s Sºº - S. - - - - - - - S. 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I- |S. | - s | º º - s i si : | - | |- | | | | | | | | *- | |/| ill - sº - - - - - s - - - - º E U R. E U R. 279 DICTIONARY OF MECHANICAL SCIENCE. EUROPE extends from the tenth degree west, to the sixtieth degree east longitude, and from the thirty-sixth to the seventy- second degree of north latitude. The Frozen Ocean-bounds it on the north, Asia on the east, the Mediterranean sea on the south, and the Atlantic Ocean on the west. Its length, from east to west, is about 3300 miles; its breadth, from north to souht, about 2350. - The European states are fourteen in number; and of these, four are in the north, six in the middle, and four in the south. The Northern States are: - Côuntries. - Chief Towns. 1. The British Isles . . . . . . . . . . London, Dublin, Edinburgh. 2. Danish dominions. . . . . . . . . . Copenhagen, on the Sound. 3. Sweden................... Stockholm, on Lake Maelar. 4. Russia.................... Petersburgh on the river Neva. - The Sir Middle Countries are, 1. France................ . . . . Paris, on the river Seine. 2. Batavia or Holland, with - • the Netherlands....... : } Amsterdam, on the river Amstel. 3. Switzerland....... . . . . . . . .Basil, on the river Rhine. 4. Germany ........... . . . . . . Vienna and Presburg, on the 5. Austrian dominions...... $ river Danube. 6. Prussia . . . . . . . . . . . . . . . . . . Berlin, on the river Sprey. The Four in the South are, 1. Spain . . . . . . . . . . . . e gº tº e º 'º ..Madrid, on river Manzanares. 2. Portugal ...... tº Q tº e º e g c s e º o Lisbon, on the river Tagus. 3. Italy . . . . . . . . . . . . ... . . . . . . . Rome, on the river Tiber. 5 Constantinople, on the Strait of 4. Turkey ........... 0 g º e o e { Constantinople. A SYNopsis of the European States. .5 × - 2: STATES. Length. Breadth. Square Miles. # Religion ‘. - 3-5 - - - 5 § $º ... ..] 380 300 79,712 | 169 |Prot. Mix. M Scotland....] 303 150 27,794 62 | do. do. & Ireland....] §§ ičo 27%;" | 137 a. i. Norway .... 1000 300 71,400 10 | do. |Monaro Denmark . . . 240 280 13,744 || 139 do. do. Sweden. . . . ] 800 500 208,912 14 | do. do. Prussia. . . . . 600 300 56,416 99 | do. do. Netherlands 350 300 17,520 | 130 | do. do. . Germany ... 600 526 191,573 || 130 ||P. & C.|M. & Ar Switzerland 150 100 14,960 28 | do. Repub. Russia . . . . . 1500 1100 1,200,000 55 |Gr. C. Despot. Poland . . . . . 540 500 160,800 75 | Cath. |Monar. § Bohemia ... 300 250 27,734 252 | do. do. & France ....| 600 500 160,374 174 | do. do. Spain ...... 700 500 150,763 74 | do. do. $ Portugal....] 306 100 27,280 67 do. do. & Italy. . . . . . . 750 | 400 116,967 170 do. do. Hungary....] 306 200 87,575 17 | do. do. Turkey .... 1400 730 181,400 44 |Maho. do. . The oceans and seas contiguous to Europe are :—1. The Atlantic ocean on the west. 2. The Frozen ocean on the north. 3. The Mediterranean sea on the south. 4. The White sea on the north of Russia. 5. The Baltic, between Denmark, Sweden, Russia, Prussia, and Germany. 6. The North sea, or German ocean. 7. The Irish sea, or St. George's channel. 8. The English channel. 9. The Adriatic, or Gulf of Venice. 10. The Archipelago, or sea of the Grecian Islands. 11. The sea of Marmora. 12. The Black sea, and the sea of Azof. The chief European bays, gulfs, and straits, are:—1, The gulf of Bothnia, in Sweden. 2. The gulf of Finland, between Sweden and Russia. 3. The bay of Biscay, between France and Spain. 4. The gulf of Venice, between Italy and Turkey. 5. The gulfs of Riga and Dantzic, in the Baltic. 6. The gulfs of Lyons, Genoa, Taranto, and Salonica, in the Mediterranean. 7. The straits are, the Sound, between Denmark and Sweden; the strait of Dover, between England and France; of Gibral- | tain. || into the white sea at Archangel. tar, between Spain and Africa; of Messina, between Italy and Sicily; of Gallipoli, into the sea of Marmora; of Constantino- ple, into the Black sea; and of Kaffa, into the sea of Azof... . . The principal European lakes and mountains are:—flakes Onega, Ladoga, and Peypus, in Russia; Wener and Weter, in Sweden; Neufchatel and Geneva, in Switzerland, and on the borders of France; and Lucerne, Zurich, and Constance, in Switzerland. - - And the mountains are:—the Alps in Switzerland, extending in the form of a crescent, for above 500 miles. The highest part of the Alps is Mont Blanc, 15,662 feet above the level of the sea. The Pyreneés, between France and Spain, whose greatest elevation is 11,000 feet. The Apennines in Italy; the Carpathian mountains, exceeding 500 miles north and east, in Hungary; the Langfiall, or Long Mountains, and Dofrefial mountains, which separate Norway, and Sweden. . - The volcanoes in Europe are:—Mount Etna in Sicily, whose base is 180 miles in circumference, and its height 11,000 feet above the level of the sea. Mount Vesuvius, in the east of Naples, about 3000 feet high ; and Mount Hecla, in Iceland, about 5000 feet above the level of the sea. The European islands in the Baltic are:—Rugen, Oeland, Gothland, and Aland, belonging to Sweden; Zealand, Funen, Alsen, Langland, Laland, Falster, Femereu, and Bornholm, belonging to Denmark; and Dago and Oesel, belonging to | Russia. In the Frozen Ocean, are Nova Zembla, belonging to Russia, and Iceland, the property of Denmark. In the Atlantic Ocean, are Great Britain and Ireland; the Orkney and Shetland islands to the north of Scotland, and the Hebrides to the west. To the north of the Shetland islands are the Ferro islands, which belong to Denmark. - In the Atlantic Ocean are also the Azore islands, the chief of which are, St. Michael, Tercera, Pico, Fayal, Florez, and Corvo. These islands belong to Portugal. - In the Irish Sea, are the isles of Man and Anglesea. In the British Channel, are the Isles of Wight, Gersey, Guernsey, Sark, and Alderney. In the Mediterranean, are the islands of Minorca, Majorca, and Ivica, off the coast of Spain, to which they belong. Cor- sica, under the government of France. Sardinia, a separate kingdom. Sicily belongs to Naples, and Malta to Great Bri- The islands of the Archipelago belong to Turkey. The Isthmuses are those of Corinth, between the Morea and Turkey, and of Precops, in the Crimea. The principal capes are:—1. The North cape, in Lapland. 2. The Naze, in Norway. 3. Land's End, in England. 4. Cape Clear, in Ireland. 5. Cape la Hogue, in France. 6. Cape Ortegal and cape Finisterre, in Spain. 7. Cape St. Vin- cent, in Portugal. 8. Cape Spartivento, in Italy; and 9. Cape Matapan, in Turkey. - The chief European rivers are:—1. The Dwina, which falls 2. The Duna, which dis- charges itself into the Baltic at Riga. 3. The Niemen, or Memel River, separating Russia and Prussia, and which falls into the Baltic near Memel. 4. The Vistula joins the sea near Dantzic. 5. The Oder falls into the Baltic below Stettin. 6. The Elbe enters the sea near Cuxhaven. 7. The Weser runs into the sea at Bremen. 8. The Rhine falls into the German ocean at Leyden. 9. The Scheldt falls into the German ocean at Flushing. 10. The Maese joins the German ocean below Rotterdam. 11. The Seine falls into the English channel at Havre-de-Grace. 12. The Loire enters the ocean at Painboeuf, 13. The Garonne, or Gironde, falls into the sea below Bour- deaux. 14. The Minao forms the northern boundary of Por- tugal. 15. The Douro falls into the sea at Oporto. 16. The Tagus below Lisbon. 17. The Guadiana separates Spain from Portugal, and falls into the Atlantic. 18. The Guadalquiver empties itself into the Atlantic at St. Lucar. 19. The Ebro falls into the Mediterranean. 20. The Rhone disembogues itself into the Mediterranean, 21. The Arno falls into the gulf of Genoa. 22. The Tiber runs into the Mediterranean. 23. The Po and the Adige fall into the gulf of Venice. 24. The Danube, the Niester, and the Dnieper fall into the Black sea. 25. The Don into the sea of Azof; and, 26. The Wolga into the Caspian sea. 280 E U R. IE U R DICTIONARY OF MECHANICAL SCIENCE. iThe British Islands.-Great Britain is situated between 50 and 584 degrees of north latitude, and between the 2d degree east and the 6th degree west longitude. Its length from north to south is about 580 miles, and its greatest breadth about 370. It is divided into England, Wales, and Scotland. Ireland is an integral párt of the British empire. The foreign possessions of Great Britain in Europe are:– Gibraltar, Malta, Guernsey, Jersey, and Heligoland. In North America—Canada, Labrador, New Brunswick, and their islands. islands, except Cuba, Hispaniola, Porto Rico. these it has Honduras. Demerara, Essequibo, and the Falkland islands. possesses the Cape of Good Hope, Sierra Leone, Senegal, Goree, the isle of St. Helena, and the Isle of France. In Asia— Hindostan, the island of Ceylon, the Banda isles, &c. New Holland and its dependencies. But in lieu of The population of the whole British empire is about sixty- | four millions of souls; of these above forty-two millions are free people. - Thus, allowing to Great Britain........ 14,956,300 Souls. To Ireland. . . . . . . . . . . . & e º e º a g º ºs e e .... 6,500,000 European dependencies. . . . . . . . . . . . . . . 180,300 American dependencies ...... • * ~ e. e. e. e. e. 486,200 West Indian dependencies...... ... ... 1,167,000 African dependencies ... . . . . . . . . . . . & © tº 129,000 Asiatic dependencies.................. 2,009,000 East India Company’s dependencies.... 40,600,000 Army and navy, including mercenary troops e e º 'º º e * c e o O e º O e º 'º G tº º e º e º e & e º 671,000 *ssmºº We shall have a grand total of... 66,698,800 In the year 1812, the British navy amounted to 1000 ships of war. Of these 262 were ships of the line, called also first-rates. In 1820, the peace establishment was fixed at 715 ships of war, and of these 262 were in commission, or actual service. The revenue of 1823 was above £51,000,000, the national debt about £800,000,000. The poor-rates in England and Wales are about £8,000,000 annually. In Scotland, the poor are not provided for by rates or taxes; hence the high moral feeling and sense of independence, with the consequent indus- try and frugality of the Scots. - The cultivated parts of England and Wales are reckoned at thirty-nine millions of acres, the uncultivated seven millions; but of these, six millions are capable of improvement. In Great Britain, all the manufactures common to Europe and Asia are brought to the greatest perfection. The tonnage of British vessels cleared outwards in the year 1824, amounted to the amazing weight of 2,492,902 tons. The British tonnage entered inwards for the year 1824, amounted to 2,960,188 tons,— Leaving in favour of our home consumption 468,786 tons, out of which of course a considerable deduction must be made for the refuse of raw materials imported. The transit trade is valued at £10,188,196, which is certainly a large sum to even a great commercial nation, as general car. riers in a period of profound peace, when the marine of Europe, and America to boot, strike in for a large share in the compe- tition of a transit trade. The inland trade may be somewhere about seventy millions sterling in 1825. The value of the exports and imports in 1824, rose to £96,488,162 sterling. According to official statements made for the year 1821, the families employed in agriculture in Great Britain, amounted to 978,656; in trade, manufactures, or handicraft, 1,350,239; not comprised in either, 612,488; being a total of 2,941,383 fami- lies;-of which 2,346,717 were in England, 146,706 in Wales, and 447,960 in Scotland. The number of inhabited houses in Great Britain, was 2,429,630. The Editor regrets exceedingly, that after much fruitless research in quest of authenticated returns of the annual value of each branch of our various manufactures, and the number of persons, male, female, and children, employed in each, he has been unable to complete a tabular view of our domestic industry in the afts and manufactures. England and Wales.—England is all that portion of Great Britain south of the Tweed and the Esk, the Cheviot Hills, and the Solway Frith. On the east it is washed by the German ocean; on the south by the English channel; on the west by the Irish sea; and its northern boundary is Scotland. Observe. The º: England and Wales is computed at 49,453 square miles; the population is reckoned just now (1825) somewhere about 12,500,000 souls; therefore, the num- ber of inhabitants to a square mile is nearly 254. In the West Indies, it possesses all the principal | There are forty counties in England, and twelve in the prin- cipality of Wales. In South America—Surinam, Berbice, | In Africa, it The sia: Northern are: County. Chief Town. Situate on the River. Northumberland, Newcastle, Tyne. Cumberland, Carlisle, Eden. Durham, Durham, Wear. Yorkshire, York, Ouse. Westmoreland, Appleby Eden. Lancashire, Lancaster, Lune. The four bordering on Wales are: Chèshire, Chester, Dee. Shropshire or Salop, Shrewsbury, Severn. Herefordshire, Hereford, Wye. Monmouthshire, Monmouth. . . Wye. Twelve Midland: Nottinghamshire, Nottingham, Trent. Derbyshire, Terby, - Derwent. Staffordshire, Stafford, Low. Leicestershire, Leicester, Soar. Rutlandshire, Okeham, * - Northamptonshire, Northampton, Non. Warwickshire, Warwick, Avon. Worcestershire, Worcester, Severn. Gloucestershire, Gloucester, Severn. Oxfordshire, Oxford, Thames Buckinghamshire, Aylesbury, Tame. Bedfordshire, JBedford, South Ouse. - Eight Eastern. Lincolnshire, Lincoln, Witham. PHuntingdonshire, Huntingdon, South Ouse. Cambridgeshire, Cambridge, Cam. Norfolk, Norwich, Yare. Suffolk, Ipswich, Orwell. Essex, Chelmsford, Chelmer. Hertfordshire, Hertford, Lea. Middlesex, London, Thames. Three South-Eastern : Surrey, Guildford, Wey. Kent, Canterbury, Stour. Sussex, Chichester, or Lewes. Four Southern : - JBerkshire, Reading, Thames. Wiltshire, Salisbury, Avon. Hampshire, Winchester, Itchyn Dorsetshire, Dorchester, Frome. Three South-Western, Somersetshire, Wells or Taunton. Devonshire, Exeter, Exe. Cornwall, Launceston, Tamar. - Siac in North Wales. Flintshire, Flint, Dee. Denbighshire, Denbigh, Clwyd. Caernarvonshire, Caernarvon. Anglesey, Beaumaris, on the Strait Menai. Merionethshire, Harlech or Bala. Montgomeryshire, Montgomery. Sia: in South Wales. Radnorshire, Radnor, - Cardiganshire, Cardigan, Tivy. Pembrokeshire, Pembroke, Milfordhaven. Caermarthenshire, Caermarthen, Towy. - Brecknockshire, Brecom, Usk. Glamorganshire, Caerdiff, Taafe. E U R E U R. 281 DICTIONARY OF MECHANICAL SCIENCE. The foregoing counties are again divided into six circuits, as follow :— . - . * , The Home. Circuit contains Essex, Hertford, Kent, Surrey, and Sussex. ... - The Norfolk Circuit contains Bucks, Bedford, Huntingdon, Cambridge, Suffolk, and Norfolk. - The Oxford Circuit contains Oxford, Berks, Gloucester, Worcester, Monmouth, Hereford, Salop, and Stafford. The Midland Circuit: Warwick, Leicester, Derby, Notting- ham, Lincoln, Rutland, and Northampton. - 4. The Western Circuit: Hants, Wilts, Dorset, Somerset, T)evon, and Cornwall. The Northern Circuit: York, Durham, Northumberland, Lancaster, Westmoreland, and Cumberland." Chester is a county palatine, and has a separate judge. In Middlesex the supreme courts of judicature are held. The Universities are those of Oxford and Cambridge, and the public schools or colleges are those of Westminster, Eton, Winchester, the Charter-house, Christ's Hospital, St. Paul’s, &c. The Royal Military schools, at Woolwich and Sandhurst. Greenwich Hospital on the Thames, is the abode of aged and disabled seamen; and Chelsea Hospital contains the worn- out and maimed soldiers of Britain. At Portsmouth, Plymouth, Chatham, Deptford, Sheerness, and Milford, the dock-yards for the navy are established. And London, Liverpool, Bristol, Hull, Yarmouth, Falmouth, Sunderland, and Whitehaven, are the chief ports for the merchant shipping. Woolwich is the great arsenal for the navy, and for the materiel of the army. The Isle of Wight, on the coast of England, is remarkable for its picturesque beauty;-Jersey, Guernsey, Alderney, and Sark, are on the coast of France. In the Irish sea is the Isle of Man, a poor island, but noted as the refuge of the unfortu- nate. The Scilly Isles are barren rocks, beyond Cornwall. The Isles of Sheppey and Thanet are on the Kentish coast; and Holy Isle, Lindisfarne, and Coquet isles, are on the Northumberland coast. The principal mountains and hills are those of Cheviot, sepa- rating England from Scotland; the Fells, in Cumberland and Yorkshire; the Malvern Hills, in Worcestershire; the Mendip, in Somersetshire; the Peak, in Derbyshire; the Wreken, in Shropshire; and the Endle, in Lancashire; and the most elevated hills are, Feet High. . Feet High. Whernside.......... 4050 | Ingleborough....... . . . 3987 Pennygant.......... 3630 | Helvellyn ............ 3324 Snowdon............ 3456 Skiddaw ............. 3270 Pendlehill........... 3411 | Saddlebak............ 3043 Cross Fell. . . . . . . . . . . 3390 In a geological view, England may be thus presented to the pupil. At the Land's End, massive and primitive rocks begin ; upon these rest several species of transition rocks, chiefly slates of different kinds; these are succeeded by secondary strata, inclining to the horizontal position; and lastly, the alluvial matter upon which Middlesex extends. This is prin- cipally clay, and may once have formed the mud at the bottom of a salt-water lake. Proceeding northward from London, towards Scotland, we arrive, in Cumberland, at primitive rocks. These are among the highest and oldest rocks in Eng- land; and from the Land's End, the chain, passing through Cumberland, extends to the northern extremity of Scotland. In fact, the length of Britain, its general form, plains, rivers, and topographical divisions, depend on this chain of mountains, much in the same way that the continent of South America derives its general characteristics from the Cordilleras. The chief rivers in England are: the Tweed, which separates Northumberland from Scotland. The Tyne, which forms the harbour of Newcastle. The Wear, on which Sunderland is built. . The Tees, forming the boundary between Durham and Yorkshire. The Esk, on which Whitby is situated. The Hum- ber, on which Hull stands. The Swale, in Yorkshire, naviga- ble from Ripon. The Derwent, in Yorkshire, navigable" to Malton. The Wharfe, in Yorkshire, navigable to Tadcaster. The Aire, which joins the Ouse at Howden, in Yorkshire. The Dom, which joins the Ouse in an artificial canal, called the Dutch river. The Trent, which joins the Ouse at Adlingfleet, *º are lost in the Humber. The Witham, forming the port of Boston, in Lincolnshire. The Welland, forming the north-west boundary of Northamptonshire. The Nen joining the Wash below Wisbeach. The Southern Ouse, falling into the Wash at Lynn Regis. The Yare, in Norfolk, which falls into the German ocean at Yarmouth. The Deben, in Suffolk, navigable to Woodbridge. The Stour, forming the boundary between Suffolk and Essex: Harwich is at the mouth of the Stour. The Coln, flowing by Colchester. The Blackwater, in the north-west corner of Essex, near Maldon, which is joined by the Chelmer, and then forms an extensive estuary, or haven, called Blackwater Bay, famous for its oysters. The Thames, which, after receiving about eight tributary streams, falls into the sea below Gravesend, in Kent. London is situate on the left bank; Southwark on its right bank. The Medway, which, rising in Sussex, and navigable from Tunbridge, falls into the sea at Sheerness. The Stour, falling into the sea at Ramsgate. The Rother, which runs by Rye; the Ouse, by Lewes; and the Arun, by Arundel. The Itchyn, falling into Southampton Bay, and the Avon, joining the Stour, from Stourminster, and falling into the sea at Christchurch. The Exe, which joins the sea below Topsham; and the Tamar, which separates Cornwall from Devonshire. The Towridge, by Biddeford, and the Taw, by Barnstable, emptying themselves into Barnstaple Bay. The Avon, navigable from Bath, which falls into the Bristol chan- nel. The Severn, which, after a course of 150 miles, forms that large arm of the sea, called the Bristol channel. The Avon, from Warwick and Stratford, joins the Severn at Tewkes- bury. And the Wye falls into the Bristol channel at Chepstow. At Chepstow, the tide rises to an extraordinary height, swell- ing from fifty to sixty feet perpendicularly. The Towey, which runs by Caermarthen, the Tivy, by Cardigan. Milford Haven, between these, is a remarkably deep inlet of the Irish sea, and the best harbour in Britain. The Dee, which falls into the Irish sea; as does also the Mersey, the Irwell, the Ribble, and the Lune. And the Eden, which empties itself into the Solway Frith. The principal canals in England are: one in Lincolnshire, extending from Lincoln to the Trent; another from Horncastle to Sleaford; a third from Grantham to the Trent. Liverpool is connected with Hull by a canal called the Grand Trunk, from the Trent, proceeding north to the Mersey. From the Grand Trunk, several minor canals extend in various directions; the chief of these is that branch which connects the Severn, Bris- tol, Tuiverpool, and Hull. Another canal unites the Severn with the Mersey; and from Coventry, the centre of the king- dom, canals extend to the Grand Trunk and the Grand Junc- tion. The Union Canal is 44 miles long, from Leicester to Northampton. Gloucester and Hereford are connected by another canal. By a course of 40 miles, the Severn is united with the Thames, by a canal from Strand to Lechlade. The Oxford canal, after a course of 92 miles, joins the Coventry canal. The Grand Junction reaches from Brentford, on the Thames, and joins the Oxford canal at Braunston in North- amptonshire, after a course of 90 miles. On the south of the Thames, another canal connects Reading and Bath. The Lan- caster canal stretches 74 miles from Kendal, in Westmoreland, to West Houghton, in Lancashire. The canal from Leeds to Liverpool winds through a circuit of 117 miles. The Rochdale canal is 31% miles long. The Peak Forest canal is 15 miles long ; and the Chesterfield canal to the Trent is 55 miles long. The chief watering places are, Bath, Cheltenham, Tunbridge, Harrowgate, &c. famous for their salubrious and sulphureous springs. On the sea-coast, in summer, Brighton, Ramsgate, Scarborough, Margate, Weymouth, Dawlish, and Swansea, are places of fashionable resort. The surface and climate of England are alike varied and unequal. Thus, Wales is celebrated for lofty mountains, broken by beautiful and extensive valleys; the south of Eng- land is generally a level alluvial soil; but towards the Wash, in Lincolnshire, it is low and fenny. Derbyshire is celebrated for its mountains and minerals. The north of Emgland is varied by hills, dales, and lakes. Here the scenery is rich and picturesque. Winander and Coniston meres (lakes) beautify Lancashire; Ulswater, the west of Westmorland; Bassen- thwaite water, and Kesswick or Derwent-water, are situated in the South of Cumberland. - 4 C 282 f tº R. E U R. DICTIOANRY OF MECHANICAL SCIENCE. The atmosphere of England is humid, aſid hence the frequent changes of weather; but its constant agitation conduces to that perpetual verdure which covers the land, and preserves it from those extremes of heat and cold to which other countries in the same latitude are exposed. The chief sea ports in England are London, which we have already noticed; Liverpool, the second port in the kingdom, trades principally with the West Indies, the East Indies, America, the Baltic, the Mediterranean, and Ireland. Bristol, next to Liverpool, trades with Ireland, the West Indies, North America, Hamburg, and the Baltic. Hull, reckoned the fourth port for commercial business, trades in coals, corn, wool, manu- factured goods, with every country in Europe, with America, the West Indies, &c. Newcastle and Shields supply the London market with coals, and carry on some trade with the Baltic, and in the Greenland fisheries. Whitby builds many vessels, and has a good coasting trade; Gainsborough has some coasting, and a little foreign trade; Boston sends vessels to the Baltic, and exports oats to London; Lynn supplies most of the inland counties with coal, timber, and wine; it exports corn and malt, and partakes in the Greenland fishery. Yarmouth is a con- siderable sea port, and besides the coasting trade, sends ships to the Baltic, Holland, Portugal, and the Mediterranean. And the Thames, below London Bridge, is crowded with ships, which convey into that capital the commerce and wealth of the globe. Chatham, a great naval arsenal, is well defended by strong fortifications; as is also Portsmouth harbour, formed by the islaud of Portsea and the Peninsula. Southompton trades with France, Jersey, and Guernsey; and Plymouth, the most considerable harbour in England for a navy, has a good brisk trade if war time. The chief manufacturing towns are Manchester for cotton goods, Leeds and Wakefield for woollen cloths, Birmingham and Sheffiield for hardware and cutlery. Cornwall is the chosen depository of the metals. Wiltshire is famed for its superfine broad cloths. Scotland.—The position of Scotland, the northern portion of Great Britain, has already been indicated. It is 260 miles long, and about 160 miles broad, at its greatest extremity. Its superficial contents are 27,793 square miles, the population 2,100,000 souls; consequently, there are nearly 72 inhabitants for every square mile. The established religion is the Presby- terian ; but there are numerous dissenters. Scotland is divided into thirty-three counties, as follow: In the North are : whose Chief Towns are, The Counties of, Orkney (Isles),...... . . . ... ...Kirkwall and Stromness. Caithness, .......... e is e s tº us & O ... Wick. Sütherland, ....... * * * * * * * * * * * Dornoch. - Ross, . . . . . . . . . . . . . . . . . . . . . ... Dingwall and Taine. Cromarty, . . . . . . . . . . . . . . . . . . Croamrty. Inverness, ... . . . . . . . . . '• * * * * * Inverness. º The Midland Division consists of, Argyle, . . . . . . . . . . . . . . . . . . . . . Inverary. Bute, . . . . . . . . . . . . . . . . . . . . . . Rothsay Nairn, . . . . . . . . . . . . . . . . . . . . . . Nairn. Murray or Elgin, . . . . . . . .....Elgin. Banff or Bamff, ...... . . . . . . . . Banff or Bamff. Aberdeen, . . . . . . . . . . . . . . . . . . Aberdeen. Mearns or Kincardine, ... . . . . . Berwie. Angus or Forfar, . . . . . . . . . . . . Montrose. Perth, tº e º 'º e º 'º º tº s 's e e i e s a e = e s s Perth. Fife, . . . . . . . . . . . . . . . . . . . . . . . . St. Andrew’s. Kinross, . . . . . . . . . . . . . . . . ....Kinross. Clackmannah, ... ... . . . . . . . . . Clackmannan. Stirling, . . . . . . . . . . . . . . . . . . . . .Stirling. Dumbarton. . . . . . . . . . . . . . . . . . Dumbarton. In the South are: West Lotnian or Linlithgow,.. Linlithgow. Mid Lothian or Edinburgh,.... Edinburgh. East Lothian or Haddington, ... Haddington and Dunbar. Berwick or Merse, ......... ..T)unse and Lauder. Renfrew. . . . . . . . . . . . . . . . . . . . Renfrew. Ayr, . . . . . . . . . . . . . . . . . . . . . . . . Ayr. its greatest breadth. | 30,370 square miles, and its population at 5,000,000 of souls, The Counties of, whose Chief Towns are, Wigton or West Galloway, ....Wigton. - Lanark or Clydesdale, . . . . . . . . Glasgow and Lanark. |Peebles or Tweedale, ......... Peebles. . - Selkirk, . . . . . . . . . . . . ......... Selkirk. Roxburgh,. . . . . . . . . . . . . . . . . . . Jedburgh. Dumfries, ..... c e º te tº a g º e º & e º sº e Dumfries. Kirkudbright or East Galloway, Kirkudbright. The Scottish isles are Bute and Arran in the Frith of Clyde; the Hebrides, west of Cantyre, are Ilay, Jura, Mull, Tiree, Col, Iona, Sky, Lewis, &c. The Orkney isles are separated from the main land by the Pentland Frith. They are twenty-six in number; but the chief is Pomona, or Mainland, and its princi- pal towns Kirkwall and Stromness. The Shetland isles, north of the Orkneys, are forty-six in number; and of these twenty- six are inhabited. The chief town is Larwick. The lakes and Friths of Scotland most noted, are, Loch Ness, Loch Lochy, -Loch Lomond,-Loch Tay,+Loch Ave, and Loch Fyne,—The Frith of Dornock,-the Murray Frith,- the Frith of Tay,+the Frith of Forth,-the Solway Frith, and the Frith of Clyde.—A Frith is an arm of the sea, running up into the land; and the term loch, or lake, is applied indifferently to a piece of fresh-water, or an arm of the sea. Thus, Loch Lomond is a fresh water lake, and Loch Fyne an arm of the sea, like the Frith of Forth. The principal mountains are, the Cheviot Hills, the Gram- pian Hills, Ben Nevis, in Invernesshire, 4350 feet above the level of the sea, and Ben Lomond, about 3200 feet high. From Ben Lomond a spectator sees Bute, Arran, the rock of Ailsa, Ireland, Pimlimmon in Wales, Skiddaw in Cumberland, &c. The chief rivers are the Spey, in Invernesshire; the Deveron, separating Banff from Aberdeenshire; the Dee and the Don, intersecting Aberdeenshire from west to east; the Tay, falling into the German ocean below Dundee ; the Forth, the most beautiful serpentine river, empties itself into the German ocean below Leith ; the Tweed, at Berwick; the Annan falls into the Solway Frith at Annan; the Nith flows by Dumfries; and the Clyde, after washing Lanark, Renfrew, Dumbarton, Argyle- shire, and Bute, empties itself into the Irish sea at the isles of Bute and Cumbras. The canals of Scotland are those of Forth and Clyde, the Caledonian canal, a canal from Glasgow to Kilwinning; and one projected from Glasgow to Edinburgh. The Forth and Clyde canal extends from the mouth of the Carron and Forth to Dalmuir Burnfoot, six miles below Glasgow, and in its course, passes over several aqueducts, the chief of which is that of Kelvin, considered one of the finest pieces of masonry in the world. The Caledonian canal, 80 miles in length, opens a communication between the Murray Frith and the western sea, along a line of lakes, from Inverness by Fort Augustus and Fort William. The surface and climate of Scotland, as contrasted with those of England, may be thus given :-The coast of Scotland is more checquered than that of England; and the former is more diversified by lakes than the latter. In the north, the moun- tains accumulate and precipitate the clouds in plentiful show- ers of rain; the air is therefore colder, the soil not so rich, and the harvests later than in England. The chief mountains here alluded to are the Grampian from Loch Lomond to the north- | west of Aberdeenshire; and the Ochill hills, south of Perth. The productions of the north of Scotland are cows, sheep, and horses, all small in size, but valuable to their owners. In the south and west, the horses and horned cattle are large and profitable; and the finest grays are bred in Ayrshire. The Highlands abound in timber and game; the western seas and lochs in cod, ling, salmon, and herrings. * The chief sea ports of Scotland, are Leith, Greenock, Glasgow, | Ayr, Saltcoats, Kilwinning, Rothsay, Aberdeen, Dundee, &c. # The chief manufacturing places are Glasgow, Paisley, Lanark, | Kilmarnock, &c. Ireland.—Ireland is an island in the Atlantic ocean, to the west of Great Britain. It is about 300 miles long, and 180 at Computing its superficial contents at there will be 164 inhabitants to each square mile. "g + E U R E U R. DICTIONARY OF MECHANICAL SCIENCE, 283 Ireland is divided into four provinces:—Leinster, in the east, containing twelve counties. Ulster, in the north, containing nine counties. Connaught, in the west, containing five coun- ties; and Mur ter, in the south, containing six counties. The Counties of Leinster are: - County. Chief Towns. Situate on the River Dublin Dublin, Liffey, * Louth, Drogheda, Boyne. Wicklow, Wicklow, Irish Sea: Wexford, Wexford, Slayney. Longford, Longford, Shannon. East Meath, Trim, Boyne. West Meath, Mullingar. King’s County, Philipstown. Queen’s County, Maryborough. Kilkenny, Kilkenny, Nore Kildare, Kildare, Carlow, Carlow, Barron. The Counties of Ulster are: Down, Downpatrick, Strangford Bay. Armagh, Armagh and Charle- mont. Monaghan, Monaghan. Cavan, Cavan. e Antrim, Carrickfergus, Bay of Carrickfergus Londonderry, Londonderry, Foyle. Tyrone, Qmagh, Fermanagh, , Enniskillen, Loch Erne. Donegal, Lifford, Foyle. The Counties of Connaught are: Leitrim, Carrick on Shannon. Roscommon, Roscommon: Mayo, Castle Bar and Bal- - lenrobe, c Sligo, Sligo, Sligo Bay. Galway, Galway. The Counties of Munster are: , Clare, Ennis. * Cork, Cork. Kerry, Tralee. Limerick, Limerick, Shannon. Tipperary, Tipperary& Clonmel. . Waterford, Waterford, Suir. The established religion and ecclesiastical discipline of Ireland, are the same as in England. . But the prevailing reli- gion is the Roman Catholic; and sectaries of various denomi- nations are met with as in England. * * There are four archbishopricks, viz. Armagh, Dublin, Cashel, and Tuam. ** ſº * There are eighteen bishopricks, viz., Clogher, Clonfert, Cloyne, Cork, Derry, Down, Dromore, Elphin, Kildare, Killala, Kilmore, Killaloe, Leighlin, Limerick, Meath, Ossory, Raphoe, and Waterford. There is only one University in Ireland, namely, that of Dublin; the Royal College of Maynooth is for the education of young men of the Roman Catholic religion; * * * ihe chief cities are Dublin, the capital, about ten miles in circumference, containing 120,000 inhabitants; Cork, the second city, has a population of 80,000 inhabitants, and is the grand market of Irish provisions; Limerick, the third city, containing 60,000 inhabitants, exports beef, hides, tallow, and butter. Waterford has 35,000 inhabitants, and exports similar commodities. Galway carries on a trade with the West Indies; Sligo is an increasing town, and Castlebar is also prosperous. Londonderry is not so famous for its commerce as for its ancient and military fame. But Belfast, originally a Scottish colony, now boasts a population of 20,000 people, employed in the manufacture of cotton, cambric, sail-cloth, linen, white glass, sugar, and earthenware. Dundalk manufactures linens and muslins; Drogheda exports grain; and Wexford is noted for its woollen manufactories. tº g tº ... - . . A canal joins Dublin by an inland navigation with Limerick, and Waterford; and there is another canal from Newry to Joch Neagh. The principal rivers are, the Shannon, the Suir, the Blackwater, the Bann, and the Liffey, And the chief lakes are, Loch Erne, Loch Neagh, Loch Corrib, Loch Rea, and Loch Derg. - * * The climate of Ireland is mild, and favourable to vegetation. And the face of the country is more level, fertile, and abundant in pasturage than Scotland. But the farmers are oppressed by speculators, called middle men, who rent farms from the landlords, and let them to the real occupiers; these last suffer equally with the proprietors, from this shocking system. º Among the natural curiosities of Ireland, we must not omit the picturesque Lake of Killarney; the Isle of Innisfallen, venerable and romantic; and the Giants’ Causeway, 600 feet in length, aud from 120 to 240 feetin breadth, and from sixteen to thirty-six feet above the level of the strand. This cause- way, which is situated about eight miles north-east from Cole- raine, consists of many thousand pillars, mostly in a vertical position, some high, others broken, but in general, sufficiently level to form a pavement projecting into the sea to an extent unknown to man. The isles belonging to Ireland, are Lambey, north-east of Dublin; at the south-eastern extremity appear the Saltee isles and the rocks of Tashard; Clare, at the southern extremity, is chiefly famed for its promontory, Cape Clear. The Hog Islands, the Skellegs, Valentia, and the Blaskets, are on the north-west, and off the coast of Kerry. The South Arran Isles lie in the Bay of Galway, and the islands of North Arran are off the coast of Donegal. Sweden, Lapland, and Norway.—Sweden, on the north-west of Europe, is 1150 miles in length, and from the Norwegian Alps to the limits of Russin, about 600 miles in breadth, The contents in square miles are 208,912, and the inhabitants being reckoned 3,000,000, there will be 14 to every square mile, Sweden is divided into several provinces, viz. Sweden pro- per, West Norland, Swedish Lapland, East Bothnia, Finland, and Norway. r - The established religion is Lutheran. There are one arch- bishopric, thirteen prelacies, and 2537 parishes. The priests are in number 1378, with 134 vicars, and 192 inspectors. - The government is absolute monarchy; and the diet, or par- liament, consists of nobles, landed gentlemen, clergy, bur- gesses or deputies of towns, and those of the peasantry. Sweden possesses only one colonial possession, the island of St. Bartholomew in the West Indies. Its army is about 48,000 men; and its navy about twenty ships of the line. The revenue about £1,500,000; the national debt £10,000,000 sterling. In their manners, the Swedes affect the politeness and frivor lities of the French; the men are commonly robust, the women slender and elegant. The Universities are those of Upsal, containing about 500 students; Lunden, 300; and Abo, equalling that of Upsal. The chief towns are Stockholm, the capital, built on seven small islands, and resembling Venice, but with greater diversity of prospect, and scenery more truly singular and romantic, Upsal, the only archbishopric, contains about 3000 inhabitants, exclusive of the students. Gothenburgh, in West Gothland, has 20,000 inhabitants, and carries on considerable commerce, and a brisk herring fishery. Carlskrona, founded by Charles XI. in 1680, contains about 11,000 inhabitants; and Abo, in Finland, 8750. Sweden manufactures iron and steel, copper and brass, cloths, hats, watches, and sail cloths. The miners amount to 25,600. - The great forests of Sweden and Norway consist chiefly of pine and fir, spruce fir; the former is called the red, the latter the white wood of commerce. * The winter maintains a lengthened and dreary sway in the north of Sweden ; and the gulf of Bothnia becomes one vast field of ice. In the south, Sweden resembles Scotland in tem- perature of climate. In the north, on the other hand, in the summer, the climate is hot, from the great length of the days, and the reflection of the sun's rays from the numerous moun- tains; for at Tornea, in Swedish Lapland, the Sun never sets for some weeks together. The Aurora Borealis sheds its ruddy light through the sky, and cheers the darkness of the winter. Sweden is more diversified than any country of Europe 284 E U R. E U R DICTIONARY OF MECHANICAL SCIENCE. except Switzerland: extensive lakes, large pellucid rivers, winding streams, foaming cataracts, gloomy forests, verdant vales, and rocks piled on rocks, on all hands greet the traveller. - ... - - The Swedish rivers are numerous, on account of the lakes and mountains. The chief are the Elfs, the Gotha, the Motalo, the Dahl, and the Bothnia. The lakes are those of Wener, Weter, Meler, Hielmar, Stor, Enara, Hernarba Staer, or the great lake, Tornea, and the Pajana in Finland, eighty miles in Iength, and fourteen miles in breadth. The chief mountains are those which divide Sweden and Swedish Lapland from Norway; and from these, successive ranges diverge in a south-east direction. . The centre of this chain, like that of the Pyrenees, is the loftiest part, and it declines towards Lapland. - There are few species of trees in Sweden beside the fir, the mountain ash, the alder, the birch, and the willow; but in the south, the lime, the elm, the ash, and the oak flourish. And the inner bark of the fir, mixed with rye-meal, furnishes to the poor a coarse bread in time of scarcity. - The Swedish horses are small, but of good mettle. The bear, the lynx, the wolf, the beaver, the otter, the glutton, the flying squirrel, the rein-deer, falcons, eagles, ducks, geese, and an infinite variety of game, are found in Sweden, and Swedish Lapland. - The mines of Sweden are the grandest in Europe; as, the gold mines of Adelfors, in the province of Smoland; the silver mines of Salberg, thirty miles west of Upsal; the copper mine in Delecarlia; the iron mines of Danamora; and an entire mountain of iron ore, near Tornea, in Lapland. - The Swedish islands in the Baltic are, Rugen, Oeland, Goth- land, and the isles of Aland, at the entrance of the Gulf of Bothnia. . Norway.—Norway, ceded to Sweden by Denmark, in lieu of Pomerania, is divided into Christiansand, Aggerhaus, Bergen, Drontheim, Norland, and Finmark. The population is esti- mated at 700,000, and has remained pure and unmixed by con- quests; hence, the Norwegians, the descendants of the ancient Fins and Laps, still retain the muscular frame, the fresh coun- tenance, and the yellow or red hair of the Normans. The Peasantry are frank without ostentation, and undaunted with- out insolence. Their ordinary dress is grey, with red button- holes, and white metal buttons; and the women dress in a petticoat and shift, with a close collar round their throat, and a black sash. The Laplanders, or Norwegians of Finmark or Lapmark, are of a small size, generally about four feet, with large heads, high cheek-bones, swarthy complexions, wide mouth and thick lips, dark eyes, and short black hair. Their usual dresses are red caps lined with fur, and robes of cloth - or skin. - The religion of Norway is the Lutheran, and there are four bishoprics. The parochial clergy are maintained by their glebes, tithes, and surplice fees. In Lapland, the sun is absent for seven weeks at a time; but the stars are then visible, and from ten to one in the day time there is a kind of twilight, by which a person may see to read without artificial light. - There are four grammar schools in Norway, and a special seminary for the Laplanders at Bergen. - The chief towns of Norway are Bergen, the capita), contain- ing a population of 19,000 souls; Christiana, with a population of 10,000 inhabitants; and Drontheim, the ancient residence of the kings of Norway, 8,000 souls. The chief products of Nor- way are wood, goats' hides, silver, copper, iron, &c. Though the most mountainous country in the world, Norway boasts a salubrious atmosphere; its inhabitants, in general, attain a good old age ; and though the weather in winter is cold, the harbours are seldom frozen. The highest land is 2,655 feet above the level of the sea; the loftiest vale, 2,000 feet; and the pine prows at an elevation of 3,000 feet. The chief river in Norway is the Glomen, full of cataracts and shoals; yet 50,000 trees are annually floated down its stream to Frederickstadt. . . Next in consequence is the Dramme, then the Louven, the Torrisdals, the Tana, and the Alten. The lakes are those of Mioss, Rands, Tyri, and Foe- mund. The first is sixty miles long, the second fifty, but not more than two in breadth, the third is fifteen miles long, and exhibits an enchanting picture of bays and creeks, diversified by corn-fields, fertile meadows, and hanging forests; and the last is thirty-five miles long and eight broad. The Maelstroom, a whirlpool on the sea-shore of Norland, proves dangerous to boats, and even to the majestic whale. The Danish Dominions.—The kingdom of Denmark consists of Zealand, Holstein, Lunenberg, Jutland, Iceland, and the Feroe Islands. Zealand is an island at the entrance of the Baltic ; Holstein and Lunenberg border qm Germany; Jutland is a tongue of land projecting from the continent at Holstein; Iceland is a large island in the Arctic Ocean; and the Feroe Islands lie north-west of Shetland. The established religion is the Lutheran; and in Denmark proper there are six bishoprics, and two in Iceland. The chief see is that of Zealand, which yields about £1,000 per annum. The parochial clergy are maintained by their glebes, tithes, and surplice fees. In Jutland, however, some of the livings do not exceed £20 a year. The government is absolute monarchy, but exercised with mildness. The population is about two millions and a half, the square contents of territory 180,000 miles, therefore there are twelve inhabitants to a square mile. The army is about 70,000 men. The revenue of Denmark is £543,554; Sleswick and Holstein, :6300,000; the West India islands, £262,000; the customs at the Sound, £122,554; Altona, £3,150. The maintenance of the government amounts to £1,050,000. The national debt is £2,600,000. - - The colonial possessions are Tranquebar, on the coast of Coromandel; Christianburgh, on the coast of Guinea; a small part of Greenland; St. Jam, St. Thomas, and St. Croix, in the West Indies. The Danish peasantry are vassals, idle, dirty, and dispirited; but the superior classes differ little from their neighbours o; the continent of Europe. Every parish of Denmark is provided with two or three schools; and the masters teach the youth their native language, writing, and arithmetic. But in Hol- stein there are sixteen grammar schools, eleven in Sleswick, and nineteen in Jutland or Denmark proper, maintained at the royal expense. The universities are those of Copenhagen and Kiel. The chief cities are Copenhagen, the capital, in the island of Zealand, with 90,000 inhabitants; and Altona on the Elbe, close to Hamburgh, with a population of 25,000 inhabitants. At Elsinore, all foreign ships entering the Baltic, pay a toll or custom-due. The canal of Kiel, twenty miles in length, unites the Baltic with the Eyder, which falls into the German sea. Denmark exports corn, horses, and black cattle; butter, fish, tallow, hides, oil, tar, pitch, resin, and timber; and it imports silks, broad cloths, wine, brandy, salt, furniture, and colonial produce. The soil of Jutland and Holstein resembles that of England; and the process of agriculture is excellent in the south. The chief river is the Eydar, the ancient boundary between Denmark and Germany. In Denmark proper, there are some hills and forests, but no mountains. - Iceland is 260 miles long, 200 broad, and contains 50,000 inhabitants. This island is famous for its volcanic mount Hecla, its boiling springs, sulphureous rivers, and the litera- ture of its natives. - - - A. The Feroe Islands, seventeen in number, have a population of 5,000; but though not unfertile, their products are scanty; and they are chiefly famed for many singular ranges of basaltic columns. - - - The Russian Empire.—Russia is the most extensive empire in the world; its length being 9,200 miles, its breadth 2,400 miles, and its superficial contents 1,200,000 square miles. Its entire population is fifty millions of inhabitants, thousands of whom are mere barbarians and savages. - Its religion is the Greek Church; the clergy are 67,000, and are exempt from taxes. There are thirty bishoprics, 18,350 cathedrals and parish churches in this empire; the monasteries are 480; the monks 7,300; the nunneries 741, and the nuns 3,000. - 'The government is a military despotism; the laws, the will of the emperor; and the provinces are managed by Viceroys, E U R. E U R. 285 DICTIONARY OF MECHANICAL SCIENCE. The greater part of the peasantry or boors are serfs or slaves; and in the bank belonging to the government, a slave was wont to be taken in pawn for forty roubles! The chief colonies of Russia are on the eastern coast of the Asiatic continent; her army is immense, but her navy incon- siderable; the revenue is not above £12,000,000; but there is hardly any national debt. - The manners and customs of the Russians are as various as their distinct countries or races; and may be viewed as those of the Laplander, the Tartar, the Asiatic, the Parisian, and the Pole. The chief towns are Moscow, Petersburgh, Archangel, To- bolsk, Irkutsk, Revel, Astracan, Cherson, Smolensko, &c. Moscow contained 1,000 places of public worship, before it was burned in 1812, and its public buildings were the most magnificent in Europe. Petersburgh boasts an extensive commerce; Cherson is the chief mart in the South of Russia; and Astracan carries on much trade with Persia and India. Russia has an extensive inland navigation of 2,400 miles, between the Baltic and Caspian seas. Its manufactures are carried on with spirit, prosperity, and profit; and its internal and foreign commerce is very considerable. The climate of Russia is various, on account of its great extent, both north and south. In the north, the winters are intensely cold; in the south, they are mild; and Summer in both is warm and genial. The soil is various, pasturage is abundant, and though the harvests are plentiful, agriculture is conducted with great negligence. The rivers of Russia are numerous, and generally on a grand scale; as, for instance, the Volga, the sovereign of IEuropean rivers; the Don or Tanais; the Neiper or ancient Boristhenes; the Dwina ; the Bog, or Hypanis; the Niester; the Narva ; the Duna; and the Niemen. The lakes are those of Imandra, in Russian Lapland; Onega, 150 miles long and thirty broad, and Ladoga, 130 miles long, and thirty broad, in the government of Onetz; the lake Peypus, sixty miles long by thirty broad; the lake Ilmen; the Beilo, or White Lake; and the Seliger, in the government of Tver. The mountains are those of Olometz and Ural, which separate Europe from Asia. But in general, Russia is a desert and level country. The animals peculiar to Russia are bears, wolves, lynxes, elks, camels, horses, sheep, reindeer, poultry, game, &c. The ..mines are chiefly iron ore, at Dougma, near Smolensk; but in the Uralian mountains gold has been discovered, Among the natural curiosities, the grotto of Kurgur, on the western side of the Uralian mountains, is of great extent, con- taining many subterraneous lakes and meadows. The ice- bergs which float in the Arctic Ocean reflect all the colours of the rainbow, and seem so many cathedrals of crystal, adorned with silver pinnacles. The chief islands belonging to Russia, are Cronstadt, in the Gulf of Finland; Oesel and Dago, in the Baltic, peopled by Estonians, or Livonians; Nova Zembla, in the White Sea; Spitzbergen; the dreary group of isles called the Seven Sisters; the Kamtschadale Islands, comprising the Kurile Isles, the Aleutian Islands, and the Renaiski group. Prussia.-Prussia dates its consequence as a kingdom among the states of Europe, at the commencement of the 18th century. Its acquisition of territory sing 1814, has been con- siderably increased by Russia and Great Britain, that the balance of power might be more advantageously distributed between the north and the south of Europe. The extent of Prussia is now about 600 miles long by 300 broad; and it comprehends the following Divisions. Towns. Rivers. 1. The Kingdom of Prussia, Konigsburg, Pregal, 2. Polish, or Western Russia, Dantzic, Vistula, 3. Part of Silesia, Breslaw, Oder, 4, Electorate of Brandenburg, Berlin, Spree, 5. Part of Pomerania, Stettin, Oder, 6. Part of Lower Saxony, Magdeburg, Elbe, 7. Part of Westphalia. Embden. Ems. The population is estimated at nine millions; and in their manners and customs, the Prussians resemble their German neighbours, They are, in general, industrious, honest, and brave. - * 30. The religion is Protestant, under the two divisions of Luthe- ran and Calvinistic; though by its recent acquisitions Prussia has now many Roman Catholic subjects. The power of the clergy is inconsiderable. The government approaches a mili- tary despotism, supported by an army of 200,000 troops; and the perpetual supply of recruits for this force, creating a con- stant uncertainty of destination for life, impedes greatly the national education. The universities are those of Frankfort on the Oder; Konigsberg and Pasna or Pasen. The chief towns are Berlin, the capital, containing a population of 142,000 inhabitants; Konigsberg, 50,000; Breslaw, the capital of Silesia; Brandenburg; Frankfort on the Oder; Magdeburg; Neufchatel; Stettin, and Thorn. The manufactures of Prussia are chiefly glass, iron, brass, paper, woollen cloth, and silk, mostly for home consumption; and the exports are timber, corn, tallow, skins, leather, flax, hemp, and linens, which pass for Dutch manufacture. In general the climate of Prussia is cold and moist; and the lower parts of Silesia are the most healthy. Though Prussia proper is fertile, the whole district, from Berlin to Potsdam, resembles a wilderness; and the peasantry are oppressed by taxation and levies for the army. * The chief rivers are the Elbe, the Spree, the Havel, the Oder, the Vistula, the Pregal, and the Memel. The lakes are the Spelding-See, and the estuaries of the Oder, the Vistula, and the Memel, called respectively the Grass Haff, the Frisce Haff, and the Curische Haff. The mountains are chiefly situ- ated in Silesia, and may be considered as northern branches of the Carpathian, yet in the north-west part of Silesia, the Spits- berg and Graftzberg are detached mountains, somewhat less clevated than the Carpathian chain. Silesia, bordering Hungary, presents continuous forests; and the forest of Masavia, not far from Warsaw, is a famous haunt of the Urus, or wild cattle of Lithuania. Prussia possesses some iron founderies; coal is found in Silesia; and the Sam- land shore of the Baltic is the repository of amber. Germany.—Germany is situated in the middle of Europe; its length is 600, and its breadth 500 miles. This country is chiefly remarkable for its political subdivisions into electorates, grand duchies, duchies, marquisates, principalities, bishop- rics, and free cities. These are all independent states united by a political tie, under the title of the Germanic Confederation. The commonly received division of Germany is into nine parts, called circles; namely, Three Northern. Three Middle. Three Southern. Westphalia, Lower Rhine, Swabia, Lower Saxony, Upper Rhine, Bavaria, Upper Saxony, Franconia, Austria. Note.—These circles are again subdivided into principalities, electorates, &c. among more than 200 independent princes; but Lubeck, Frankfort, Bremen, and Hamburg, are sovereign states, governed by their own magistrates. The climate of Germany is temperate, inclined rather to cold than heat, and the soil is rich and fertile both for corn and pasture. In their character the Germans are open and free; inured to labour, they are dexterous in manufactures, fruitful in in- ventions, and when called into the army make good soldiers. The population is twenty-five millions, and the army 400,000 contingent troops. The religion of north Germany is the Reformed or Protestant, while in the south the Roman Catholic faith prevails. And the government is aristocratical, but its chief magistrate may be of the Catholic, the Lutheran, or the Calvinistic faith. The chief rivers are the Elbe, the Weser, the Rhine, and the Danube. The chief towns are Dresden, Meissen, Witten- burg, Magdeburg, and Hamburg, on the banks of the Elbe ; Bevern, Minden, and Bremen, on the banks of the Weser; Dusseldorf, Coblentz, Heidelberg, on the Rhine; Ulm, Neu- burg, Ratisbon, Passau, Vienna, and Presburg, on the Danube; Munich, Prague, Stutgard, and Frankfort. The chief lakes are those of Plau, in the duchy of Mecklen- burg; the Baden-See, or lake of Constance; and the Chiem- See, in Upper Bavaria. The mountains are those of the Hartz, forming a fine amphitheatre, 3000 feet high at the great Broken, its greatest ridge; the Minden Hills in Westphalia; the Erzge- 4 D 286 JE U R. IE U R. DICTIONARY OF MECHANICAL SCIENCE, berg, or Metallic Mountain, extending between Bohemia and Saxony, and supplying silver, tin, and other metals; the moun- tains of the Black Forest; the Tyrolese Alps; and the Carpa- thian chain. The Dromling-wald (forest) is to the north of Magdeburg; the Sollinge-wald, are the woody mountains of the Hartz; the Lutten-wald is the Thuringian forest; in the south is the forest of Spessart; the Black Forest is south of the Mayn in Swabia. The oak is the prevailing tree in all these forests; and the wild boar feeds on its fruit. The chief German states on the north of the Mayn, are Saxony, Brunswick, Lunenburg, Hessia, Mecklenburg, the duchy of Brunswick, the city of Hamburg, some smaller states, and the ecclesiastical powers. Sarony.—In this division the Elector of Saxony is the chief potentate, and his dominions, (which include Saxony proper, Voigtland, in the south; Lusatia, in the east; a part of Thu- ringia, in the west; and a part of Misnia and Heneberg, extend from east to west 200 miles, and from north to South about 130 miles. The religion of Saxony is the Protestant; the bishoprics are Merseberg and Naumberg; the sovereign can issue no laws without the consent of the nobles, the clergy, and the burgesses, who assemble sextennially to regulate the taxes and imposts; the army is computed at 24,000 men. The chief cities are Leipsic, the celebrated mart of German literature, with a population of 30,000 inhabitants; and Dres- den, with a population of 50,000 inhabitants. The chief manu- factures are thread, linen, laces, ribbons, velvets, carpets, paper, colours, glass, and porcelain. Saxony is famous for its tin, copper, lead, iron, and silver mines; and its agricultural products are both numerous and plentiful. Indeed, the country between Meissen and Dresden rivals the north of Italy, and many parts of Germany are in- debted to it for hops, flax, hemp, tobacco, Saffron, madder, and wine. The Kingdom of Hanover.—The electorate of Brunswick Lunenberg, or Hanover, has been erected into a kingdom dependent on Great Britain, since the peace of Paris in 1814. This electorate comprises Luneberg, Bremen, Verden, and Saxe Lunenberg, adjacent to Holstein, on the north bank of the Elbe. In the south it has Calenburg, and Grubenhagen; in the west Diepholtz and Hoya ; and Danueberg in the east. Its length is 180 miles from east to west, and about 100 from north to south. The religion is Lutheran, and the government is conducted by a council of regency, appointed by the king of Great Britain. The chief towns are Hanover, containing about 16,000 inha- bitants; Gottingen, 7,600 souls; Verden, Luneburg, Lunen- burg, Zell, Einbeck, and Osterode. The manufactures are linen, cotton, and broad cloths; the exports, metals, linens, timber, cattle, and grain ; the agricultural products are wheat, rye, barley, oats, peas, haricots, flax, hemp, tobacco, madder, fruits, potatoes, &c. The chief rivers are the Elbe, the Weser, the Leina, the Aller, the Ilmenau, and the small streams of Loha, Lutter, Fuse, and Siber; and there are a few small Jakes, as those of Dieplwitz and Stinhudder; but the forests, though numerous, are not extensive. The bishoprick of Osnabruck, in Westphalia, is considered an appendage of Hanover. A prince of the house of Hanover exercises the civil and criminal, and the archbishop of Cologne, the spiritual superiority, of the bishopric of Osnabruck, whose inhabitants are computed at 120,000 souls, and its revenue at £26,250 sterling. Hesse Cassel.-Hessia, or Hesse Cassel, is about cighty miles long, and about the same in breadth. Its inhabitants are about 750,000 souls; and its military force has amounted to 12,000 men. It abounds in game and fish, fossils and minerals; silver, copper, lead, fine clays, marble, and alabaster are also found; and the vales are diversified with vineyards and fields, fertile in corn and pasturage, and watered by the Rhine, the Mayn, and numerous smaller rivers. The religion is the Reformed; and there are three orders of the state, nobles, clergy, and burgesses, from Cassel, Marburg, and some other towns. The universities are those of Marburg, Rintelin, and Giessen. Cassel contains about 22,000 inhabit- ants; the county of Hanau about 100,000 souls. The Duchy of Mecklenburg.—The duchy of Mecklenburg con- tains 4,800 square miles, peopled by 375,000 inhabitants. It is divided into Schiverin and Gustro, celebrated for their lakes, heaths, and marshes, with a sandy soil that produces only rye and oats. The religion is Lutheran, with six superintendants and an university at Rostock. The taxation is regulated by: the states, consisting of the nobility and burgesses. The manufactures are chiefly wool and tobacco; the exports by Lubec and Hamburg, are grain, flax, hemp, hops, wax, honey, cattle, butter, cheese, fruits, feathers, dried geese, tallow, lin- seed, wool, and timber. Hamburg.—Hamburg, the third city of Germany, contains 100,000 inhabitants, who are ruled by an aristocratic senate of thirty-seven persons. The religion is the Lutheran. Its trade lies in linen and woollen cloth, wines and sugars, coffee, spiceries, metals, tobacco, timber, leather, corn, dried fish, and furs. & The Principality of Oldenburg, &c.—The principality of Olden- burg has 75,000 inhabitants; Pomerania, now the property of Denmark, 100,000; the principality of Anhalt, about 100,000; Nassau, 130,000; Schwartzburg in Thuringia, 100,000; Wal- deck, 80,000; the county of Lippe in Westphalia, 95,000; the county of Reuss, 66,000; Frankfort on the Mayn, 36,000; and the town of Papenburg, with its 3000 souls, in East Friesland, belongs to the Baron of Landsberg Veelen. The Ecclesiastical States, &c.—The ecclesiastical states are, 1. The elector of Mentz, who holds the city of Erfurth, and 15,000 inhabitants. 2. The elector of Triers, or Treves. 3. The elector of Cologne. 4. The bishoprics of Munster, Osna- bruck, Paderborn in Westphalia, and Liege. 5. The bishop- ric of Hildesheim, in Lower Saxony. 6. Of Fulda, in the Upper Rhine: and, 7. Wurtzburg, in Franconia. The eccle- siastical electorates contain a population of 300,000 inhabit- ants; the bishoprics average from 70,000 to 200,000 each. The German states south of the Mayn, are, the electorate of Bavaria, conjoined with the Palatinate, the duchy of Wirtem- berg, those of Anspach and Salzia, with the smaller states and the ecclesiastical powers. The preponderating powers in the south of Germany, are Bavaria and Wirtemberg; now erected into kingdoms. The Kingdom of Bavaria.—The kingdom of Bavaria is divided into Upper and Lower, and what is called the Higher Palatinate; the first is a mountainous country, the second champaign and fertile; but, in general, the country is woody, interspersed with lakes of various sizes. The religion is Catholic; the inhabit- ants about two millions; the revenue £1,166,600; the military force about 15,000 men. The chief rivers are the Danube, the Inn, the Iser, the Lech, the Nab, and the Neckar. Munich, the capital, is the most elegant city of Germany, and its popu- lation amounts to 38,000 souls. Landshut and Strauben are in Lower Bavaria; Ratisbon is an imperial city; Manheim, in the Palatinate of the Rhine, contains 24,000 inhabitants; and Heidelburg is famous for its wines. The states, or parliaments, are composed of the clergy, mobility, and burgesses. The only college is at Ingolstadt, but Munich has an academy of sciences. The Kingdom of Wirtemburg.—The kingdom of Wirtemburg contains about 600,000 inhabitants, and next to Saxony, is the best in the empire, being by far the most considerable and fer- tile part of the circle of Swabia. The Black Forest supplies it with timber and fuel, and the castle of Wirtemburg, in the bailliage of Canstadt, gives name to the kingdom. The re- ligion is Lutheran, and the church is ruled by four superinten- dants, called abbots, and thirty-eight rural deans. The chief city is Stutgard; and Zubingen, the second city, is celebrated for its university. Minor States.—Anspach, or Onolsbach, with Bayreuth, has a population of 320,000, on 2,300 square miles of territory. The principality of Bayreuth, or Culmbach, with Onolsbach, forms the chief power of Franconia, now annexed to the sovereignty | of Prussia. The margraviate of Baden, situated between the Rhine and the kingdom of Wirtemburg, is fertile in wine, corn, and fruit, and has abundance of fish, wood, and game. The population E U R E U R DICTIONARY OF MECHANICAL SCIENCE. 287 is estimated at 200,000 inhabitants; and the city of Nuremberg contains 30,000 souls. Salzia, and the archbishopric of Saltzburg, possesses a population of 250,000 souls, peopling 2,880 square miles. This see was founded in 716, by St. Rupert, an Englishman, and the archbishop is primate of all Germany. Saltzburg has 20,000 inhabitants, and the archbishopric sways many fair lordships in Austria, Stiria, and Carinthia. The sees south of the Mayn, are: 1. The archbishopric of Saltzburg. 2. The bishopric of Wurtzburg. 3. Bramburg, containing 180,000 souls. 4. Speyr, or Spire, 50,000 inha- bitants. 5. Aichstett, in the southern corner of Franconia. 6. Augsburg, in Suabia. 7. Constance. 8. Strasburg. 9. Kemp- tin, Buchau, and Lindau, Abatial territories; with the priory of Ellsvangen. 10. The bishopric of Passau, in Bavaria, with a population of 25,000. 11. That of Freysingen, with the terri- tory of Wendenfels, near the Rhaetian Alps, contains 23,000 souls : and 12. The bishopric of Ratisbon. Austria.—The Austrian dominions border those of Russia and Turkey on the east; Prussia, Upper Saxony, Bavaria, and Swabia, bound them on the north; Swisserland, and the Italian states, skirt their southern limits. In length 760, in breadth, 520 miles. The contents in square miles are 184,000; and there are 184 inhabitants to every square mile. Venetian Dalmatia, and some Italian territory, has fallen to the lot of Austria, whose population is now about 30,000,000. The Aus- trian dominions comprehend: Chief Towns. Rivers. The Archduchy tº : º of Austria, Vienna, Danube. Austria Duchy of Stiria, Gratz, Muchr. includin Carniola, Laybach, Laybach. * g C Carinthia, Clagenfurt, Glan. 2. The kingdom of Bohemia, Prague, Danube. 3. Moravia, } olºnd 4. Part of Silesia, Troppau, Oppa. 5. Part of Bavaria, east of the Inn. Upper Hungary, Presburg, Danube. 6. Hungary, y Lower Hungary, Buda, or Offen, including Sclavonia, Eszeg, Drave. Croatia, Carlstadt, Culp, 7. Transylvania, Hermanstadt. 8. Part of tº a g Lamburg, or R Poland, bor- Galitzia } Leopold, 5 Bug. dered by the Lodominia, Cracow, Vistula. river Bug, The established religion is the Roman Catholic, but the government is exceedingly tolerant of all religious persuasions; for, in Moravia and Bohemia, Protestants of various sects abound; and the Lutherans are little inferior in number to the Romanists. The government is absolute monarchy, supported by an enormous military force of above 300,000 men. The revenue is computed at 10,000,000 sterling, and the national debt at 40,000,000 sterling. The Austrians are reserved, but civil ; and their women, though elegant in their manners, are destitute of those mental accomplishments which give the females of France and Britain such an ascendancy. Hungary has an aristocratical senate ; and Austria its states, consisting of the four orders of clergy, peers, knights, and bur- gesses. The laws are, however, mild and salutary; but while the Austrians live contented, the Hungarians are too often dissatisfied with their masters, and disposed to anarchy. The universities are those of Vienna, Prague, Inspruck, Gratz, Buda, Debretzin, and Erlau. The chief cities and towns are, Vienna, the capital of the Austrian dominions, on the south, or rather the west side of the Danube, containing about 254,000 inhabitants; Prague, the capital of Bohemia, containing 80,000; Gratz, the capital of Stiria, 35,000 souls; Presburg, the capital of Hungary, 270,000 inhabitants; Buda, 20,000; Lemberg, or Leopold, in Poland, 20.000; Cracow, the ancient capital of Poland, 24,000; Brun, in Moravia, 18,000; Olmutz, in the same country, 12,000; Troppau, in Austrian-Silesia, 12,000; Inspruck and Trent, each, 10,000; and Trieste, 18,000. The climate of Austria is mild and salubrious; but the air of Hungary is damp and cold, from numerous lakes and morasses. The general outline of the Austrian territory is finely variegated, and sufficiently irrigated for every species of European vege- table product. And the soil is fertile and productive, notwith- standing the general neglect of agriculture. - . The chief rivers are the Elbe, the Danube; the Tiess, which falls into the Danube near Belgrade; the Save, which forms the boundary between Austria and Turkey; the Drave, which joins the Danube below Eszeg, and the Inn, which joins the Danube at Passau. The Raab and the Leytha are intermediate streams between the Drave and the Inn. The Mulda joins the Elbe near Melnich; and the Morau joins the Danube not far from Procoburg. The principal lakes are those of Traun and Ebernsee, in Austria Proper; Clagenfurt, in Carinthia; the Cirknitz-see, in Carniola; the Platten-see, in Hungary, abound- ing with fish; the Neusidler, in the vicinity of Eisenstadt; Palitzen, on the east of the Tiess; and the Tsege Zo, in Tran- sylvania. The lake of Cirknitz is a complete natural curiosity, eight miles long by four broad. In the month of June, the water descends under ground, through numerous crevices in the bottom ; but in September it again reascends with consi– derable violence, thus yielding rich pasturage in summer, and an abundance of fish in winter. The chief mountains are, the Rhaetian, or Tyrolese Alps; the Brenner mountains, or Rhaetian Alps; the glaciers of Ver- ner, west and north of Inspruck; the Lobel mountains, which separate Carinthia and Carniola; and the Julian, or Carnic Alps, which divide Carinthia from Italy. The Carpathian mountains, 900 feet high, which bound Hungary on the north and east; and the Sudetic chain, which, branching from the Carpathian, divides Bohemia and Moravia from Silesia, and the Prussian dominions. - The forests in Austria are both numerous and extensive, clad with elm, lime, birch, and alder trees; oak, chestnut, and beech trees; the black and white poplar, and aspen; syca- mores and maples; the ash, the pine, the fir, and the larch. Horses run wild in these forests; the cattle are of a slaty-blue colour; the Hungarian sheep have long erect spiral horns, and hairy fleeces. The urus, or bison, ranges the forests of Carpa- thia; the bear, the boar, the wolf, the chamois, the marmot, and the beaver, are among the numerous wild quadrupeds. The Kingdom of the Netherlands.-This kingdom, comprising Holland and the Low Countries, was erected into a sove- reignty, by the treaty of Vienna, in 1815. Holland is composed of seven provinces, called after the following names, with their chief towns : The Provinces of Chief Towns and Rivers. Holland, . . . . . . . . . . . . . . Amsterdam, and the Hague. Derventer, on the river Yssel, and Zwoll on the river Aa. Overyssel, … } Zealand, . . . . . © º e º e º e o e Middleburg, on the isle of Walcheren. Friesland, ....... e e e º 'º º Leewarden canal. - Utrecht, . . . . . . . . . . .... Utrecht, on the Rhine. Groningen, . . . . . . . . . . . . Groningen canal. Guelderland, . . . . . . . . . . Arnheim, on the Rhine. Zutphen, . . . . . . . . . . .... Zutphen, on the Yssel. . These provinces, with the Netherlands, and the duchy of Luxemburg, comprise the most fertile countries in Europe, inhabited by 7,000,000 of wealthy and industrious people. The Dutch, like all plain-dealing people, are ceremonious, rather than polite; and in distinction to a Parisian the Hollander seems to say, “I would rather be unmannerly than trouble- some.” The Protestant-Calvinistic religion prevails in Holland; but in the Netherlands there are numerous Roman Catholic fami- lies; and there are not a few Lutherans and Jews to be met with. The colonies are situate in the East and West Indies, and at the Cape of Good Hope. The army may be computed at 60,000 troops in war-time, and the navy once amounted to about forty ships of the line. - - At Rotterdam, Breda, Middleburg, and Groningen, there are very celebrated Latin schools; Leyden, Utrecht, Harder- wyck, Tranecker, and Groningen, are famous for their univer- sities; Amsterdam and Deventer have two inferior colleges; and Haerlem is noted for its academy of sciences. The chief cities and towns are, Amsterdam, whose population amounts to 288 E U R. H U R DICTIONARY OF MECHANICAL SCIENCE. 212,000 souls, and its haven is one forest of masts; Leyden, containing 50,000 inhabitants; Rotterdam, 48,000; Haerlem, 40,000; the Hague, though esteemed only a village, 36,000; Middleburg, in Zealand, 30,000; and Utrecht, Delft, Dort, and Groningen, each about 20,000 inhabitants. . . s , e No country in Europe boasts an equal inland navigation with Holland; a circumstance easily accounted for by the fact, that the land is almost every where lower than the Sea, which is kept out by dams and dykes. A country so low, and from its abundant inland navigation so level, must, of necessity, possess a humid and cold climate; and where the combination of land and water, with scanty elevations of barren sand, is very intimate, we cannot expect that agriculture will be consi- derable, though the pasturage may be rich, and even abundant. Hence Holland is the country for the manufacture of butter; and so scrupulous are the good women about their cows' warmth and cleanliness, that it is no uncommon thing to see whole herds in the meadows clothed with mantles and Coverlets. The chief rivers are the Rhine and the Meuse; and the chief lake is the sea of Haerlem. Flanders, an integral part of the kingdom of the Netherlands, is about 180 miles long, reckoning from the eastern limit of Luxembourg to Ostend, and 120 in breadth, from the northern boundary of Austrian Brabant to the most southern limit of Hainault; covering a surface of 7,520 square miles, and peo- pled by 1,900,000 inhabitants. The religion is the Roman Catholic, and the bishoprics are those of Bruges, Antwerp, Ghent, &c.; in all nine, under the archbishopric, or metro- politan see of Mechlin. Religious pageantry dazzles the un- iettered devotee. The universities of Tournay, Douay, and St. Omer, have long been famous. The chief cities and towns are, Brussels, containing 80,000, Ghent 60,000, Antwerp 50,000, Mons 25,000, Bruges 20,000, Namur 20,000, Luxembourg 12,000, Roermond 10,000, and Limbourg, 8,000 inhabitants; Sluys, and Ostend. Brussels is celebrated for its manufacture of lace; Ghent for its Venetian site, being built on a number of little islands; Antwerp as the chief mart of Flemish com- merce; and Cambray is renowned for its cambrics. The climate is more remarkable for moisture than for warmth; but agriculture flourishes well, and the Netherlands yield not to Lombardy, or England, in the essentials of good husbandry. The chief rivers are, the Rhine; the Meuse, or Maes; the Scheldt; the Dyle, and the Nethe. The forest of Soigne is in Brabant; and the remains of the ancient forest of Ardennes pervade Hainault and Luxembourg, from Valenciennes to Treves. France.—This country, 600 miles in length from north to south, and 560 in breadth from east to west, was formerly divided into provinces; but, since the revolution, it has been divided into departments. The following table contains both divisions. Province. Department. City. River. Flandrº } Nord Lille T) eule Françoise Artois Pas du Calais Arras Scarpe Ficardie Somme Amiens Somme r Bas Seine Rouen Seine Calvados Caen Orne Normandie Manche Coutances Orne Alençon Sarte Eure Evreux Iton Seine T’aris Seine Isle de Seine & Oise Versailles Seine Fr Oise Beauvais Therain TarłC6 Aisne Laon Seine & Marne Melun Seine - Châlons-sur- Marne } Marne Marne Champagne & Ardennes Mézières Meuse A Aube Troyes Seine Haute Marne Chaumont Marne - \; Bar-le-Duc. Ornain . tº Oselle Mentz Moselle Lorraine {: Nancy Meurthe Vosges Epinal Moselle Province. Department. . City. . River. - Alsace $ Haut Rhin Colmar Fetcht & Lauch & Bas Rhin Strasburg Rhine Ille & Vilaine Rennes Vilaine Côtes du Nord St. Brieux Near the Sea Bretagne Finisterre Quimper Oder Morbihan Vannes Sea-port Loire Infre Nantes Loire Maine et } Sarthe Le Mans Sarte Perche Mayenne Laval Mayenne & Mayenne and - r Anjou } Loire } Angers Mayenne Touraine Indre & Loire Tours Loire Loiret Orleans Loire Orleannois {; & Loire Chartres Eure Loire & Cher Blois #. º Indre Chàteauroux Indre Berri } Cher Bourges Eure Nivernois Nievre Nevers Loire Yonne Auxerre 3. Côte d'Or I)ijon uche Bourgogne }: & Loire Mágon Saône Ain Bourg Ressouze ( Haute Saône Vesoul Franche Doubs Besançon Doubs Comté Jura } Lº-sau- Walliere (Vendée { * * Vendée Poitou Deux Sèvres Niort Sèvres Vienne Poitiers Claiu Haute Vienne comprising immor º Marche } part of Li- }~ Vienne In OSIIl Creuse Guéret Creuze Corrèze, com- - tº e prising part (, Limosin of Haute Wi- }* - Corrèze 6 Inne Bourbonnois Allier Moulins Allier Saintonge, ſº C ºis; *::::::... } Saintes Charante Aunis Angoumois .jºins } Charente Angouleme Charante Saintonge Puy de Dôme Clermont Auvergne } Cantel St. Flour Lyonnois, ; Rhône Lyon Rhône Forêt & 3 Loire Montbrison Beaujoleis Isère Grenoble Isère . . Hautes Alps Gap Dauphiné } Drôme Valence Rhône Dordogne Perigueux Ille Gironde Bordeaux Gironde Lot & Garonne Agen Garonne . º, 6– ! Lot Čáhors Lot hen .# 119. Aveyron Rhodez Aveyron Gascoºne Gers Auch Gers gne Landes Mºe Mar. Douze Hautes Pyrénées Tarbe Adour - Bearne Basses Pyrénées Pau Le Cave de Pau Comté de Foix Arriege Tarasgon Arriege Roussillon } *ś, Terpignan' Tot . Haute Garonne Toulouse Garonne Aude Carcassonne . Aude Tarne Castres Agout L d Garde Nimes Vistre anguedoc Lozere Mende Lot Ardèche Privas Near the Rhône Haute Loire Le Puy Borne : Héraut Montpellier E U R. E U R 289 DICTIONARY OF MECHANICAL SCIENCE. Province. Department. City. River. Bouches du º Provence Rhone } Aix Arc r0V6I1 Basses Alps Digne Var Toulon Mediter. Sea • Golo Bastia Corsica - } Liamone. Ajaccio et Bastia . The conquests made by France during the late wars, from 1792 to 1814, are not integral parts of her dominions; as most of them have been given up to their parent states. - ...The islands belonging to France, are the isles of Hieres, near Toulon, which are the same as Homer's isle of Calypso, in the Mediterranean ; the isles of Rhe, Belleisle, and Oleron, near Rochelle, are in the bay of Biscay. Corsica is the birth- place of Napoleon Buonaparte. - The established religion in France is the Roman Catholic; but the Gallican Church is more independent of the See of Rome than that of any other country professing the same faith. Before the revolution, there were in France 17 archbishops, 750 great convents of monks, and 200 nunneries: the monks and nuns were reckoned 200,000, and the revenues of the clergy and religious houses six millions sterling. - The government is an hereditary monarchy, confined to the male branches of the house of Bourbon, in the succession of Charles X. ; then the Duke of Angouleme; the Duke of Bour- deaux, son of the Duke de Berri; the Duke of Orleans, and his sons; Prince of Condé, &c. - The population is estimated at 31 millions; and the army at 250,000 men; the navy is inconsiderable ; the revenue is about 25 millions sterling. The French in their manners possess a singular degree of vivacity and gaiety, and frivolity of dispo- sition; and their politeness is the result of affectation and pride, rather than of physical purity and tutored elegance. In some branches of experimental philosophy the French have made considerable progress, but in regard to mechanics, and the application of machinery in abridging labour, they have always been the pupils of the British. The universities of France were formerly those of Douay, Cäen, Paris, Rheims, Nanci, Strasbourg, in the north ; Nantes, Angers, Poitiers, Orleans, Bourges, Dijon, Besançon, in the middle; and Bour- deaux, Pan, Perpignan, Toulouse, Montpellier, Aix, Orange, and Valence, in the south. The chief cities are, Paris, the capital, with a population of 600,000 inhabitants; Lyons, 100,000, and famous for its manu- factures of articles of luxury; Marseilles and Bourdeaux, each peopled with about 80,000 inhabitants; Lisle, noted for its fortifications, boasts a population of 60,000 inhabitants ; Ami- ens, 40,000; Rouen, the capital of Normandy, 72,000; Brest, the chief maritime arsenal, 30,000; Nantes, 56,000; Orleans, 40,000; Strasbourg, 40,000; and Thoulouse, 50,000 souls. ... The inland navigation of France is confined to the canal of Briare, or Burgundy; the canal of Orleans; the canal of Picardy; and that of Languedoc, planned and executed by the engineer Riquet, during the ministry of Colbert, in the reign of Louis XIV. - - In regard to its climate, France may be divided into three regions: the bleak air of the north ; the salubrious atmosphere of the middle region; and the genial south, so inviting to in- valids from Britain. are diversified with rivers, canals, forests, and mountains ; but in general the plain predominates. Cornwall finds its rival in the gravelly heaths of Britany; from Flanders to Orleans a rich loam prevails, like what we meet with in Middlesex, and the adjacent counties; the mountainous region of the south is fertile; and the common products are corn, grapes, fruits, olives, tobacco, hemp, flax, silk, manna, and saffron. - The chief rivers are the Seine, the Loire, the Rhone, the Garonne : and the lakes are those of Provence, among the Vosges of Alsace, and some other provinces. The mountains are those of Britany, the Vosges, Mount Jura, the Alpine ridges of Dauphiné; the Cevennes, about 6000 feet high ; and the Pyrénées. The forests are Orleans, Ardennes, the former the retreat of banditti, the latter renowned for deeds of chivalry; and the forest of Fontainebleau. The desert of La Crau, com- prising a plain of 150,000 acres, of Provence, is entirely com- © The north, west, and interior of France, posed of round gravel, or shingle, than which the sea shore is not more barren. Spain.—Spain, from west to east is about 600 miles long, and from north to south the breadth is reckoned 500 miles; and situated between the 36th and 44th degrees of north lati- tude; the climate is delightful and the soil luxuriant. The population is estimated at 11 millions; the army at . 60,000; and the revenue at five millions and a half sterling. The government is absolute and hereditary monarchy. Spain. is at present divided into 22 provinces for the crown of Castile, and four for Arragon. Those for Castile are, the kingdom of Gallicia, the provinces of Burgos, Leon, Zamora, Salamanca, Estremadura, Valencia, Valladolid, Segovia, Avila, Toro, Toledo, La Mancha, Murcia, Guadalaxara, Cuença, Soria, Madrid, and Andalusia. The four for Arragon were formerly the Moorish kingdoms of Seville, Cordova, Jaen, and Grenada. The most common and generally received division of Spain is as follows: w - Ringdoms. Capitals. The kingdom of Gallicia, .... St. Jago di Compostella. The principality of Asturias, Oviedo. The lordship of Biscay, ...... Bilboa. | The kingdom of Navarre, .... Pampeluna. The kingdom of Leon, ....... Leon. The kingdom of Old Castile, ... Burgos. The kingdom of Arragon, .... Saragossa. The principality of Catalonia, Barcelona. The province of Estremadura, Badajos. The kingdom of New Castile, Madrid. The kingdom of Valencia,.... Valencia. The kingdom of Andalusia, ... Seville. The kingdom of Murcia, . . . . . Murcia. The kingdom of Grenada, ..... Grenada. M The Islands of ajorca,. . . . . . e Majorca. *:::::: RT; *}; Minorca, . . . . . . a 16 are:S Port Mahon. The chief rivers are the Ebro, the Douro, the Tagus, the Guadiana, and the Guadalquiver; the Bidasoa and the Tinto. And among the lofty mountains of this country we may enu- merate the Pyrenees, the Cantabrian mountains, the Mountain of the Sierra Molina, the Sierra Morena, the Sierra Nevada, Montserrat, and Gibraltar. The Ebro falls into the Mediter- ranean, the Douro into the Atlantic at Oporto, the Tagus into the Atlantic at Lisbon, the Guadiana into the Bay of Cadiz, the Guadalquiver into the Atlantic at St. Lucar, the Bidasoa separates France and Spain, and the Tinto, or Yellow Stream, empties itself into the Mediterranean at Huelva. The Pyrenees separate France from Spain; the Cantabrian moun- tains extend from Roncevalles to Cape Finisterre ; the Molina separate Old from New Castile; the Morena divides Castile and Estremadura from Andalusia; the Nevada, or Snow Mountains, run east and west through Grenada; Montserrat is 3300 feet high, and 30 miles from Barcelona ; and Gibraltar, the Calpe of the ancients, is the key to the Mediterranean, held by Great Britain. The chief cities and towns in the kingdom of Gallicia are, St. Jago, Corunna, Ferrol, Moldonedo, Lugo, Ortense, and Tuy. In Asturias are Oviedo, Santillana, Aviles, and St. Vin- cent. In Biscay are Bilboa, Tolosa, Vittoria, and Malaga. In Andalusia are Seville, Cordova, Cadiz, and Xeres. In Old Castile are Burgos and Valladolid. In Navarre are Pampe- luna, Olita, Tudela, Estella, and Sangues. Saragossa, Terra- cona, Huesca, Bulbastro, Teruel, Ainsa, and Jaen, are in Arragon. Catalonia is celebrated for the most industrious inhabitants of Spain, and their chief towns are, Barcelona, Montenello, Tarragona, and Roses, anciently called Rhodope. In Valencia are, Valencia, Monviedro, Gandia, and Alicant. Murcia and Castigna are in the kingdom of Murcia. In Gre- nada are, Grenada, Soria, Segovia, Madrid, and Toledo. In Leon are, Leon, Salamanca, Zamora, and Ciudad Rodrigo. In Estremadura are, Merida, Badajos, and Placentia. . . . Though the climate be generally healthy, the solano, a noxious wind, which blows from the south-east, produces a sensation bordering on madness ; but its duration seldom exceeds three days. And, except in the two Castiles, the soil, 4 B - - 296). E U R E U R" I) ICTION ARY OF MECHANICAL SCIENCE. so peculiarly fertile, abounds in excellent pastures, vineyārds, ſ , * t groves of orange and lemon trees. The horses have long been celebrated for their Arabian beauty and fleetness; and the sheep called Merinos yield the government an annual profit of £1,666,666 sterling. Wolves, bears, and locusts, are com- mon in Spain; it is celebrated also for its hares, partridges, pheasants, and game of various kinds. . . - t The Spaniards are proud and cold upon a first introduction to strangers, but possess, on acquaintance, both urbanity and vivacity under this repulsive exterior. Their sobriety and temperance are proverbial; and the grandees and nobles live, in general, in a state of much simplicity, without parade or ostentation; but upon particular occasions they display a splendour and magnificence not to be equalled by the nobility of any other kingdom. They are fond of theatrical amuse- ments, bull-fights, and dancing. - - The religion is the Roman Catholic, and the inquisition has reigned with exorbitant power. the bishoprics are forty-six; and the clergy and religious persons are computed at 188,625 ! exempt from the usual avocations of life. The Spanish people had embraced a free constitution, and re-established their parliament or Cortes; but their ungrateful monarch, by the help of French bayonets, has remounted an absolute throne, and ecclesiastical domination has, at the same time, resumed its tyranny over the public mind. Portugal.-Portugal, the most westernly country of Europe, is about 360 miles long, and 120 broad; and the population is about two millions and a half. The religion is Roman Catholic, the government absolute and hereditary monarchy; but the royal family have emigrated to Brazil, and Portugal now is governed by a viceroy | vinces, viz. –1. Entre Douro e Minho. Beira. 4. Estremadura. 5. Alentejo. 2. Tra los Montes. 6. Algarva. 3. The chief colonies are Brazil, Madeira, and some settle- ments on the coast of Africa, with Goa and Macao in the East Indies. - The army is computed at 24,000 men; the naval power thir- teen sail of the line, and fifteen frigates; and the revenue two millions sterling. The Portuguese are, in general, an elegant people; the peasantry are miserable vassals of the nobility, whose prejudices are pernicious and impolitic. The chief cities and towns are, Lisbon, the capital, with a population of 200,000 inhabitants; Oporto, 30,000; Braga, Coimbra, Ivora, and Tavora. The climate is excellently salu- brious, and the country is generally fertile, abounding in vine- yards, groves of orange and lemon trees, but agriculture is little cultivated. - The chief rivers are the Tagus, the Mondega, the Toro, and the Cadaon. ; And the mountains are those of Idubeda, pass- ing the town of Guarda; the chain of Arrabeda, in Estrenna- dura; and the chain of Alentejo, running between the city of Ivora and the town of Estramas; and Cintra, near Lisbon. The Portuguese islands are, the Azores, comprising the isles of St. Michael Tercera, Pico, or the Peak, Fayal, Horez, and Corvo. In general, these islands are mountainous, and ex- posed to earthquakes and violent storms, yet their produce of wheat, wine, fruits, and wood, is very abundant. Switzerland.—This country is bounded on the east by the Tyrol and Austrian Suabia, on the west by France, on the north by the Black Forest, and on the south by Savoy and Italy. Its length, from east to west, is 200 miles, and its breadth about 130 from north to south, Switzerland is the most mountainous country in Europe, but the air is salubrious, the soil fertile, and its wildest regions are diversified by cultivated fields and vineyards, extensive lakes and verdant vales, umbrageous woods and frightful glaciers. The Thirteen original Cantons are: The Cantons of Towns. Lakes. Rivers. 1. Zurich, . . . . . . . . Zurich, ... ... . . . . . Zurich. 2. Berne, ... . . . . . . . Berne, ... © º ſº º Aar. 3. Basil, . . . . . . . . ... Basil, . . . . . . . . . . • * c e s e Rhine. 4. Underwalden, ... Stanz and Sarne. + 5. Schweitz, ...... Schweitz. - 6. Zng, . . . . . . . . . . . U15, . . . . . . . . . . . . . . Zug. 7. Glaris, ... . . . . . . Glaris The archbishops are eight, Portugal is divided into six pro- | numerous and picturesque. The Cantons of Towns. . Lakes. JRiverg. 8. Soleure, ........ Soleure, . . . . . . . . . . º e & Aar. 9. Uri, ... . . . . . . . . . Altorf, . . . . . . . 0 g º O - e. Reuss. 10. Appenzell, ...... Appenzell. 11. Lucerne, ....... Lucerne,........... Lucerne. 12. Fribourg,....... Fribourg, .... . . . . . . . . . . Sanen. 13. Schaffhausen ... Schaffhausen, . . . . . . . Rhine. In 1803, the following cantons were added by the French to Switzerland:—Argovia, Thuringia, Tessin, Grisons, St. Gall, and Vaud. - t The religion of Switzerland is mixed ; some cantons profess- ing Catholicism, while others are Calvinistic Protestants. The Catholic cantons are, Uri, Schweitz, Underwalden, Zug, Lucerne, Fribourg, Soleure, Berne. The Protestant are, Zurich, Basil, Schaffhausen, Part of Glaris, and Appenzell. The government is a strange mixture of aristocracy, venal oligarchy, and bold democracy; and under these respective forms, we find laws sufficiently jealous and severe ; but the people are renowned for their morality and frank indepen- dence. The population amounts to two millions of souls; the military force is reckoned at 20,000 men; and the revenue about a million sterling. But taxation must be moderate where the people are proverbially poor; and foreign subsidies, aris- ing from the permission of the youth to serve as mercenaries in the armies of other countries, swell the resources to equal the expenditure. - The city of Basil contains 14,000 inhabitants, and is cele- brated for its university; Berne 13,000, and its college; Zurich, for its college and public library; Lausanne, 9000 inhabitants; Fribourg and Schaffhausen each 6000, and Lucerne 5000. The chief rivers are the Rhine and the Rhone, the Aar and the Reuss, the Lien and the Fleur ; and the lakes are both Constance, Geneva, Maggiore, Lugano, Neufchatel, Zurich, and Lucerne, are the chief lakes. The mountains are, the Alps, covered with snow at their sum- mits; Mount Rosa, Mount Blanc, Mount St. Bernard, and Mount St. Gothard. The horses of Switzerland are esteemed for their vigour and spirit; and the ibex (a species of goat) is as common among the Alps as are goats in Wales. In the day he ascends the highest summits, but at night he seeks the valleys to browze on aromatic plants. When scared, the ibex will dart up a perpen- dicular rock of eighteen feet high, at three springs; bounding like a racket-ball struck against a stone wall. The chamois and the marmot are common; and in the highest Alps the bearded vulture preys upon the white hare, the marmot, the chamois, kids, and lambs. - Italy.—This country is usually divided into three parts, the northern, middle, and southern. It is a beautiful and fertile peninsula, assuming the appearance of a boot-leg on the map, and admirably adapted for commerce. Its length is 670, and its medial breadth 100 miles. The population is thirteen mil- lions; of which, allowing six millions for Naples and Sicily, and three millions for the Pope's dominions, there will be four millions for the northern states. - In the north the Alpine scenery is truly sublime; the Apen- nines give many charms to the central part; Florence and Tivoli excite the traveller's admiration; and Naples is genc- rally beautiful, though exposed to the fiery irruptions of Vesuvius. The chief rivers are the Po, the Adige, the Brenta, the Piara, the Arno, and the Tiber, with the Rubicon, or Fiumessino, a diminutive stream which falls into the Adriatic. The lakes are those of Maggiore, Locamo, Lugano, Como, Lecco, Iseo, Di Garda, in the north ; Perugia, Bolsena, Rieti, Albano, and Nemi, in the central part; and Celano, and Varano, in the Neapolitan territory. The mountains are the Alps, the Apen- nines, and Vesuvius. Naples and Sicily forming the southern part, may be regarded - as one kingdom. Sicily, separated from Naples by the strait of Messina, is an island about 170 miles long and 80 broad. Next to Constantinople, Naples is the most charming city, for situation, in Europe. The Strait of Messina is celebrated for the Scylla and Cha- rybdis of the ancients; the former being a lofty rock on the E U. R. E W A 291. DICTIONARY OF MECHANICAL SCIENCE, . Calabrian shore, and the latter a spot where the waves, greatly agitated by numerous pointed rocks at the bottom of the sea, assume the appearance of a whirlpool. - The Lipari isles, adjacent to Sicily, are celebrated for their rocks of volcanic glass, and the grotto of the sea ox—a cavern 60 feet high, 200 feet long, and 120 feet broad, situated in Felicuda. Malta and Gogo are valuable in a maritime point of view. The central part of Italy, comprising the dominions of the Church, Tuscany, Lucca, St. Marino, Piombino, and the isle of: Elba, may be thus illustrated:—The dominions of the Church yield £350,000 sterling annually; the revenue of the Grand Duchy of Tuscany is half a million yearly ; the Luccanese are the most industrious people of Italy; the diminutive republic of St. Marino claims the Pope's protection; the principality of Piombino, on the Italian shore, and opposite to the isle of Elba, is a neglected spot, and both are known best for their iron ores. - - Piedmont, Milan, Mantua, Parma, and Placentia, Modena, and Genoa, in the north of Italy, now claim our attention. Piedmont, with Savoy, is 150 miles long and 100 broad, and belongs to the King of Sardinia. The capital of Piedmont is Turin, containing 80,000 inhabit- ants; Vercelli, 20,000; Alexandria, 12,000; a little to the east of which is Marengo. - The fertile duchy of Milan contains 2432 square miles, and a population of more than a million of inhabitants. Milan, the chief city, contains 120,000 inhabitants; Pavia is celebrated for its university, as is also Padua; and Verona is not more renowned for its antiquities, than Venice for its enchanting maritime situation, and the wealth of its merchants. The small duchy of Mantua contains but 12,000 inhabitants; while that of Modena boasts a population of 320,000, and a revenue of £140,000. - The population of Parma and Placentia is reckoned 300,000; the revenue £175,000; the soil is rich, the pastures fine, and the Parmesan cheese has been celebrated for centuries. Genoa assumed the title of the Liburian Republic shortly after 1798; but it now belongs to Sardinia. The population is computed at 400,000; the city, 80,000; and the troops, 30,000. Lombardy, Mantua, the ancient Republic of Venice, and Dalmatia, belong now to Austria; the grand duchy of Tuscany to the Archduke Ferdinand; and Parma and Placentia to the ex-empress Maria Louisa. Turkey in Europe.-The Turkish dominions, contain 182,560 square miles, comprising many ancient kingdoms and repub- lics, whose classic names but tell the fleeting grandeur of remote antiquity. The following are the names, both ancient and modern, of the provinces of the Turkish empire: º Modern. Ancient. 1. Moldavia, north, . . . . . . . . Dacia. 2. Budzac, or Bessarabia, ... Getae and Peucini. 3. Walachia, . . . . . . . . . . . . . . Dacia. 4. Bulgaria, . . . . . . . . . . . . . . . Moesia. 5. Romelia, . . . . . . . . . . . . . . . & Thracia, Paeonia, Macedonia, Graecia. 6. The Morea, . . . . . . . . . . . . . Peloponnesus. 7. Albania, . . . . . . . . . . . . . . . . $º Chaonia, and Part of Illyricum. 8. Dalmatia, . . . . . . . . . . . . . . . Dalmatia. 9. Servia, . . . . . . . . . . . . . . . . gº 10. Bosnia, . . . . . . . . . . . . . . . . . } Pannonia. 11. Turkish Croatia, . . . . . . . . Pannonia and Noricum. Turkey extends 870 miles from north to south, and 680 in breadth from east to west; and its population may be esti- mated at eight millions. The established religion is the Mahommedan; but about two-thirds of the people are Greek Christians, who, along with their religion, retain their priests, bishops, archbishops, and patriarchs. In the Mahommedan faith there are also the mufti, or pontiff, who presides at Con- stantinople ; the moublahs, or doctors of the law, the Koran being a code of civil and religious observance; the inferior muftis, or judges, and the cadilesquiers, or chief justices; the imaums, or parish priests, who perform the service of the chia round Ismail, and some in Albania. mosques; the dervishes, or monks, of whom there are four . various orders, or institutions. - The government is, despotic, but the sultan's power, subject to the laws of the Koran, is wisely balanced by a religious aristocracy. The Turkish navy amounts to thirty ships of the line ; and the army to 150,000 ill-disciplined and mutinous troops. The revenue is computed at seven millions sterling, partly derived from a capitation tax on unbelievers, and partly from a land tax and the customs. - - The Turks are abstemious in diet; their chief furniture is the carpet which covers the floor; their amusements partake of indolent apathy; but the personal cleanliness of both sexes is highly laudable. - The chief cities and towns are, Constantinople, with a popu- lation of 400,000 souls; of whom 200,000 are Turks, 100,000 Greeks, and the remainder Armenians, Jews, and Franks. Adrianople, 140 miles north-west of Constantinople. Filipopoli, a mean town, whose situation is so low, that the mud in its streets is sometimes knee deep, and the foot passengers get along only by stones, erected like posts, to facilitate the inter- course of a wretched . city considerable in size. Sosia has 70,000 inhabitants; Silistria, in Bulgaria, 60,000; Bucharest, in Walachia, 60,000; Jaffy, in Moldavia, and Bender, in Bes- sarabia, each 12,000; Belgrade, in Servia, 25,000; Banjaluka, in Bosnia, 18,009; Salonica, 60,000; Larissa, 25,000; while Atini (Athens) is a miserable village. - Turkey is famous for carpets, currants, figs, saffron, statuary marble, silk, and drugs. w The climate is delicious, the air pure, and the seasons regu- lar; and though the soil be rich, agriculture is neglected; and the Turks excel in no one useful art or science. The chief rivers are the Danube, the Maritz, or ancient Hebrus, which falls into the AEgean sea; the Esker; the Morava, anciently the Margus ; and the Drin, which falls into the Save. The lakes are chiefly found in Budzac and Wala- The mountains are those of Haemus, Acroceraunia, Pindus, Olympus, Ossa, Pelius, and Mount Athos, resembling Mount Serrat in Spain, and celebrated for its monasteries and cells of devout hermits. The islands belonging to Turkey in Europe are, Cerigo and Candia on the south coast of the Morea ; Milo, Santerim, Stampalin, Paros, Naxia, Engia, Zia, and Zine, on the east; Andro, Negropont, and Skyros, east of Livadia. South of the island of Paros is Antiparos, whose grotto is the admiration of travellers. The whole isle is one huge rock of fine white marble, and the grotto is distinguished from the caverns in Derbyshire, by the snowy whiteness of the calcareous spar which appears on either hand, or suspended from the roof in the most elegant and picturesque forms. The present struggle in Greece for liberty, is so very problematical, that we have kept entirely aloof from the political aspect which this once classic land now wears. - On the west of Epirus are Corfu, St. Maura, Ithaca, Cepha- lonia, and Zante, forming a new republic, under the protection of Great Britain. EUTOCIUS, an eminent mathematician, who lived at the time of the decline of the sciences in Greece, was a native of Ascalon, in Palestine, and a disciple of Isodorus, one of the celebrated architects employed by the emperor Justinian. He probably flourished about the commencement of the sixth cen- tury, though we have no particulars respecting his life; but his works reflect much honour on his memory. He wrote elaborate and perspicuous “Commentaries on the Books of Archimedes concerning the Sphere and Cylinder;” and also on the first four books of the conics of “Apollonius Pergaeus.” These commentaries have not only elucidated many difficult passages in those profound writers, but have tended to throw light on the history of mathematics. EWAPORATION, in Natural Philosophy, is the conversion of water into vapour, which becoming lighter than the atmo- sphere, is carried considerably above the earth's surface; and afterwards by a partial condensation forms clouds, and finally descends in rain. Various hypotheses have been advanced to account for the process of evaporation, some attributing it to one cause, and some to another; and it is difficult to say which has the greater claim to attention, as none of them 292 E V E E W H . DICTIONARY OF MECHANICAL SCIENCE, appear perfectly satisfactory. This being, the case, and as our limits will not admit of a long detail of all the theories that have been written on this subject, our remarks shall embrace the most interesting experiments, observations, and phenomena, relating to evaporation.—That water salted to about the same degree as salt-water, and exposed to a heat equal to that of a summer's day, did, from a circular surface of about eight, inches’ diameter, evaporate at the rate of six ounces in twenty-four hours. Whence, by calculation, the thickness of the pellicle or skin of water, evaporated in two hours, was the fifty-third part of an inch ; but, for a round number, suppose it only a sixtieth part; then, if water as warm as the air in summer evaporates the thickness of one- sixtieth part of an inch in two hours, from its whole surface, in twelve hours it will evaporate the tenth of an inch : which quantity will be found abundantly sufficient to furnish all the rains, springs, dews, &c. By this experiment, every ten square inches of surface of the water yield in vapour, daily, a cubic inch of water: and each square foot, half a wine pint; every space of four feet square, a gallon;, a mile square, 6914 tuns; and a square degree, of 69 English miles, will evaporate 33,000,000 tuns a day; and the whole Mediterranean, com: puted to contain 160 square degrees, at least 5280,000,000 of tuns each day. A surface of eight square inches, evaporated, purely by the natural warmth of the weather without wind or sun in the course of a whole year, 16,292 grains of water, or 64 cubic inches; the depth of water, therefore, evaporated in 12 months, amounts to 8 inches. But the annual evaporation is actually from 48 to 36; inches. Water evidently evaporates more in windy than in calm weather, as the fleecy vaporous air is then more speedily dissipated. And in May, June, July, and August, the evaporation is greatest. Many experiments have been made to determine the precise rate of evaporation by different philosophers, and we learn that the evaporation is confined entirely to the surface of the water: hence it is in all cases proportional to the surface of the water exposed to the atmosphere. Much more vapour of course rises in mari: time countries, or those interspersed with lakes, than in inland countries. Much more vapour rises during hot weather than during cold; hence the quantity evaporated depends in some measure upon temperature. The precise law has been happily discovered by Dalton, who says, in general, the quantity eva- porated from a given surface of water per minute, at any tem- perature, is to the quantity evaporated from the same surface at 2129, as the force of vapour at the first temperature is to the force of vapour at 212°. Hence, in order to discover the quantity which will be lost by evaporation from water of a given temperature, we have only to ascertain the force of vapour at that temperature. Hence, we see that the presence of atmospheric air obstructs the evaporation of water; but this evaporation is overcome in proportion to the force of the vapour. The quantity of vapour which rises from water, even when the temperature is the same, varies according to circum- stances. It is least of all in calm weather, greater when a breeze blows, and greatest of all with a strong wind. See FREEZING. EVECTION, in Astronomy, the most considerable of the lunar irregularities, caused by the action of the sun upon the moon; the lunar evection was discovered by Ptolemy, and is the first irregularity in the motion of this body with which the ancients were acquainted. Its general and constant effect is to diminish the equation of the centre in the syzigies, and to increase it in the quadrature, and may be explained by a change supposed to take place in the eccentricity of the lunar orbit, and at the same time a motion in the apogee. This inequality can be represented very exactly, by supposing it proportional to the sine of double the angular distance of the moon from the sun, minus the mean anomaly of the moon, and the co-efficient to this proportion is now generally stated in modern astronomical works at 1° 20'28", whence the formula for the evection is (1920'28") x sin. 2 dist. ( G) — mean anomaly ) from which it is easy to follow the successive variations of this equation, for in order to this it is only requisite to consider the different values which its argument can take. It is also very easy to find the period of evection from the variation in the value of the angle on which it depends. For this purpose it will be sufficient to calculate the variations of this, angle in a given time, and thence to conclude by a simple proportion, the number of days necessary for it to vary 360°. This period differs but little from the periodic revolution of the moon; viz. 27-178533 days. - . . . " . . EVERGREEN, in Gardening, a species of perennials which continue their verdure all the year. - - ...EVICTION, signifies a recovery of lands or tenements by I &W. * - - EVIDENCE, in Law, proof by testimony of witness on oath, or by writings, or records adduced before a court, or compe- tent jurisdiction. It is twofold, written or verbal ; the former by records, deeds, bonds, or other documents; the latter by . witnesses examined viva voce, and called technically, parole. evidence. It is also either absolute or presumptive; and may, be that which is given in proof by the parties, or which the jury know of themselves, for every thing which makes a fact or thing evident to them, is called evidence. & & Witnesses are summoned by writ of subpoena to attend, on penalty of £100 to the king, and £10 to the party, besides damages sustained by their non-attendance. All witnesses of all religions, who believe in a future state of rewards and punishments, are received, but not persons infamous in law by. their crimes, nor persons directly interested in the matter at issue; and no counsel or attorney shall be compelled to disclose the secrets intrusted to him by his client, but he may give evidence of facts which he knew by other means than for the purpose of the cause. One witness is sufficient to any fact, except in high treason, when two are required ; but that is only in treasons of conspiracy against the state, and not trea- son relating to the coin, &c. The oath of the witness is to speak the truth, the whole truth, and nothing but the truth ; and all evidence is to be given in open court. The general rules of evidence are:–1. The best evidence must be given that the nature of the thing is capable of 2. No person inte- rested in the question can be a witness; but to this there are exceptions; as, first, in criminal prosecutions; secondly, for general usage, for convenience of trade, as a servant to prove. the delivery of goods, though it tends to clear himself of neg- lect. 3. Where the witness acquires the interest by his own act, after the party who calls him has a right to his evidence. The third rule is, that hearsay of a matter of fact is no evi- dence ; but of matter of reputation, such as a custom, it is in. some sort evidence. 4. Where a general character is the mat- ter in issue, particular facts may be received in evidence, but. not where it occurs incidentally. 5. In every issue the affirma- tive is to be proved. 6. No evidence must be given of what is agreed, or not denied, upon the pleadings. - Of Persons competent to give Evidence.—The king cannot be a witness under his sign manual, and a peer must be sworn. A judge and juror may give evidence. Members of a corpo- ration cannot be heard in a cause of the corporation. In actions against churchwardens, &c. for money misspent, &c. parishioners may be evidence. Kinsmen are not to be objected to. Husband and wife are not received as witnesses for or against each other; and the bail. cannot be a witness for his principal, on account of his direct interest in the event. One that has any benefit under a will, or deed, must release it before he can prove it as a witness; any devise to a person who is witness to a will, or codicil, is void, and he shall be received as a witness. A bare trustee, it is said, may prove a deed made to himself. In actions for penalties on usury, the borrower, after he has paid his money, may be a witness to prove it. In actions against the hundred, a party is received as a witness in his own cause. Persons not of sound memory, attainted of praemunire or conspiracy, convicted of felony, perjury, or other infamous crimes, are incompetent to be received as witnesses; but these are restored to competency by the king’s pardon; and the witness shall not be asked any question to accuse himself, but it must be proved by producing the conviction; but upon conviction of perjury, under statute 5 Eliz. c. 9, nothing but a reversal of judgment can restore a man to competency. - . . Wills of land must be attested and subscribed in the pre- sence of the testator by three witnesses. In general, the E X G E X G 293 DRCTIONARY OF MEGHANICAL SCIENCE. courts are inclined to favour the receiving of evidence, and to || consider objections as to interest, to go more to the credibility of the witness than to his competency. - When a witness is not liable to any legal objection, he is first examined by the counsel for the party on whose behalf he comes to give evidence, which is called his examination in chief, who is not to put what is called leading questions, viz. to form them into such a way as would instruct the witnesses in the answers he is to give. He is then cross-examined by the other side, when leading questions are necessarily put; and then he is re-examined as to what he has been asked in his eross-examination. The party examined must depose those facts only of which he has an immediate knowledge and recol- lection ; he may refresh his memory with notes taken by him- self at the time, and if he can then speak positively as to his recollection, it is sufficient; but if he have no recollection fur- ther than finding the entry in his book, the book itself must be produced. Deeds, receipts, and writings requiring stamps, must be stamped before they can be received in evidence. Parole evidence shall not be admitted to annul or substantially vary a written instrument, nor to explain the meaning of a tes- tator in a will, though where there are two persons of the same name, and it is doubtful which is the devisee, from an imperfect description, it must be proved by witnesses which is the devisee. By the statute of frauds, several things must be evidenced by writing, which previously might be proved by parole only. The general rule has been, for the last century, under the ablest judges, that no man shall be asked a question, the answer to which might subject him to criminal punishment or pecuniary penalty. It has been lately attempted by some judges to extend it further, to prevent any question being asked which may degrade a man's character, which it is feared will deprive the parties of all the substantial benefits of cross-examination. EVOLUTION, in War, the motion made by a body of troops, when obliged to change their form and disposition, to preserve a post, or occupy another, to attack an enemy with more advantage, or to be in a better condition of defending themselves. r - Two LUTION, in Arithmetic and Algebra, is the extraction of roots; being thus opposed to involution, which is the rising of powers. EXCENTRICITY of The ORBIT of A PLANET, in Astro- nomy, is the distance between the centre and the focus of the ellipse in which it revolves. The discovery of the excentricity in the orbits of the sun and moon is attributed to Hipparchus, who wrote a treatise on this subject 150 years before our era. The .ecentricity of the orbit is computed from the greatest equation of the centre, by the following proposition: As 57° 17'44."8, (the arc = rad.) is to half the greatest equation, so is • * sº e - | judicial, which is subdivided into a court of equity, and a court BXCEPTION, in Law, is a stop or stay to any action. In law proceedings, it is a denial of matter alleged in bar to an action; and in chancery, it is what is alleged against the suffi- º º | of the supplies granted for the year, and receivable in all pay- EXCESS, in Arithmetic and Geometry, is the difference e | at various rates according to the current rate of interest at the EXCHANGE, in Arithmetic, is the reduction of different rad. = 1 to the excnetricity. See AstronoMY and EQUATION. ciency of an answer. between any two unequal numbers or quantities. coins or any denominations of money, whether there be real coins answering to them or not, from one to another : or the method of -finding how many of one species, or denomination, are equal in value to a given number of another; in order to which it is necessary to know the value of the coins and moneys of account of different countries, and their proportion The several operations in this case are only different applications The par of exchange is always fixed and certain, it being the intrinsic value of foreign money, compared with sterling; but the course of exchange rises and falls upon Thus in some parts of France, they keep their accounts as at Paris, Lyons, and Rouen, in livres, sols, to each other according to the settled rate of exchange. of the rule of three. various occasions. and deniers, and exchange by the crown, - 4s. 6d. at par; and to change French into sterling, we say, As one crown is to the given rate, so is the French sum to the sterling required; or thus, to change sterling into French, As the rate of exchange is to one crown, so is the sterling sum to the French required. To illustrate which, take these examples: 1. How many crowns must 2. A merchant at Paris re- be paid at Paris, to receive mits to his correspondent in in London £180 exchange at | London 800 crowns, at 4s. 6d. 4s. 6d. per crown? | each, which is the value in sterling 2 d. cr. £. C}", d, C?". As 54 : 1 : : 180 : As 1 : 54 : : 800 : 240 3. - 54 54)43200 800 cr. 12) 43200 432 . £. 180 And these examples will suffice for other places; for where the rate of exchange is known, we can easily determine how much must be paid or received in any transaction with a foreign country. Arbitration, or Comparison of ExCHANG e, determines the method of remitting to, or drawing upon, foreign places, in such a manner as shall be most advantageous to the merchant, and is either simple or compound. Simple Arbitration, respects three places only. Here, by comparing the par of arbitration between a first and second place, and between the first and a third, the rate between the second and third is discovered; from whence a person can judge how to remit or draw to the most advantage, and to determine what that advantage is. Compound Arbitration, respects the cases in which the exchanges among three, four, or more places are concerned. A person who knows at what rate he can draw or remit directly, and also has advice of the course of exchange in foreign parts, may trace out a path for circulating his money, through more or fewer of such places, and also in such order, as to make a benefit of his skill and credit; and in this lies the great art of such negociations. - Exchange, in Law, is a mutual grant of equal interests, the one in consideration of the other. In exchange, the estates of both parties should be equal; that is, if the one has a fee- simple in the one land, the other should have a like estate in the other land ; and if the one has fee-tail in the one land, the other ought to have the like estate in the other land: and so of other estates. - - - EXCHEQUER, an ancient court of record, established by William the Conqueror, and intended principally to order the revenues of the crown, and to recover the king's debts and duties. The court consists of two divisions, viz. the receipt of the exchequer, which manages the royal revenue ; and the of common law. Exchequer Bills, bills or tickets issued by the Exchequer, payable out of the produce of a particular tax, or generally out ments to the exchequer. The interest payable on them has been time they were issued; those at present (1824) in circulation, bear interest at the rate of 2d. a day per cent. They are fre- quently made out for £100 each, but those issued of late years have been chiefly for £1000 each, and they have sometimes been made for much larger sums; they are numbered arithme- tically, and registered accordingly, for the purpose of paying them off in regular course, the time of which is notified by public advertisement. The daily transactions between the bank and the exchequer are chiefly carried on by these bills, which are deposited by the bank in the exchequer to the amount of the sums received by them on account of government; the bank notes and cash thus received by the bank being retained by them, as the detail part of the money-concerns of government is all transacted at the bank. The instalments on loans are paid into the receipt of the exchequer in exchequer bills, which are received again by the bank as cash, either for the amount of dividends due, or in repayment of advances. When these bills sell at a considerable discount, or any other circumstance indicates that the quantity of them in circulation is too great, the usual expedient is to fund a part of them, that is, to con- 4 F 294 E X E E X E DICTIONARY OF MECHANICAL SCIENCE. vert them into a permanent debt, by offering the holders of them stock in lieu of their bills. EXCISE DUties, inland taxes on commodities of general | consumption, but in general, the articles subjected to it have been such as are not absolutely essential to subsistence. Salt appears to have been the object of an excise duty at a very early period; in later times, oil, wine, tobacco, and various other consumable articles, have been burdened with duties of this description. - e Excise, one of the principal branches of the public revenue, consisting of inland duties, or taxes on articles manufactured or consumed, whereas the duties of customs are paid on goods brought into or carried out of the country: . tº Excise, in Law, is an inland imposition, sometimes paid upon the consumption of the commodity; or frequently upon the retail sale, which is the last stage previous to the consump- tion. For more easily levying the revenue of the excise, the kingdom of England and Wales is divided into about fifty col- lections, some of which are called by the names of particular counties, others by the names of great towns; where one county is divided into several collections, or where a collection com- prehends the contiguous parts of several counties, every such collection is subdivided into several districts, within which there is a supervisor; and each district is again subdivided into out-rides and foot-walks, within each of which there is a gauger or surveying officer. The officers of excise are to be appointed, and may be dismissed, replaced, or altered, by the commissioners, under their hands and seals; their salaries are allowed and established by the Treasury. If it be proved by two witnesses, that any officer has demanded or taken any money, or other reward whatever, except of the king, such offender shall forfeit his office. By several statutes, no process can be sued out against any officer of excise, for any act done in the execution of his office, until one month after notice given, specifying the cause of action, and the name and abode of the person who is to begin, and the attorney who is to conduct the action; and within one month after such notice, the officer may tender amends, and plead such tender in bar; and having ten- dered insufficient or no amends, he may, with leave of the court, before issue joined, pay money into court. Officers of excise are empowered to search at all times of the day, enter warehouses, or places for tea, coffee, &c. But private houses can only be searched upon oath of the suspicion, before a com- missioner or justice of the peace, who can, by their warrant, authorize a search. The office of excise has also several excellent regulations for procuring the due attention and good conduct of their officers. EXCIUSION, in Mathematics, is a method of coming at the solution of numerical problems, by previously throwing out such numbers as are of no use in solving the question. - EXCOECARIA, a genus of the triandria order, in the dioecia class of plants; and in the natural method ranking under the 38th order, tricoccae. There are two species. The agallocha, or aloes wood, is a native of China and some of the India islands, and is about the same height and form as the olive tree. Its trunk is of three colours, and contains as many sorts of wood: the heart is that of tambac, or calombac, which is dearer in the Indies than gold. EXCOMMUNICATION, an ecclesiastical penalty or cen- sure, whereby such persons as are guilty of any notorious crime or offence, are separated from the communion of the church, and deprived of all spiritual advantages. EXCORIATION, in Medicine and Surgery, the galling or rubbing off the cuticle, or external skin. EXCRETION, or Secretion, in Medicine, a separation of some fluid, mixed with the blood, by means of the glands. EXECUTION, in Law, is a judicial writ, grounded on the judgment of the court whence it issues; and is supposed to be granted by the court, at the request of the party at whose suit it is issued, to give him satisfaction on the judgment which he hath obtained ; and therefore an execution cannot be sued out in one court, upon a judgment obtained in another. These are of different sorts, according to the nature of the action: in actions were money is recovered, as a debt or damages, they are of five sorts; 1. against the body of the defendant; 2. or against his goods or chattels; 3, against his goods and the profits of his lands; 4. against the goods and the possession of his lands; 5. against all three, his body, lands, and goods. Execution of Criminals, must be according to the judgment; and the king cannot alter a judgment from hanging to behead- ing, because no execution can be warranted, unless it be pur- suant to the judgment. This being the completion of human punishment, in all cases, as well capital as otherwise, must be performed by the legal officer, the sheriff or his deputy. Mur- derers are to be executed the day next but one after convic- tion, unless it be Sunday, and anatomized ; for which reason they are generally tried on a Friday. - EXECUTOR, a person appointed by the testator to carry into execution his will and testament after his decease. The regular mode of appointing an executor is, by naming him expressly in the will ; but any words indicating an intention of the testator to appoint an executor, will be deemed a suffi- cient appeintment. - EXEGESIS, a discourse by way of explanation, or comment, upon any subject. - EXEMPLIFICATION of Letters PATENT, a transcript or duplicate of them, made from the enrolment thereof, and sealed with the great seal. - EXERCISE, the preparatory practice of managing the artil- lery and small arms, in order to make the ship’s crew perfectly skilled therein, so as to direct its execution successfully in the time of battle. . The exercise of the great guns of our navy has been as well as all others, very complicated, and abound- ing with superfluities, but the following concise method has been introduced by an officer of distinguished abilities, with much success. As these instructions abound with several technical terms, the reader, whenever at a loss, may look for any of those articles, which are all explained in this work. Exercise of the Great Guns. 1st. Silence. 8th. Fire. 2d. Cast loose your guns. 9th. Sponge your guns. 3d. Level your guns. 10th. Load with cartridge. 4th. Take out your tompions. | 11th. Shot your guns. 5th. Run out your guns. 12th. Put in your tompions. 6th. Prime. 13th. House your guus. 7th. Point your guns. 14th. Secure your guns. Upon beating to arms (every person having immediately repaired to his quarters) the midshipman, commanding a num- ber of guns, is to see that they are not without every necessary article, as (at every gun) a sponge, powder-horn, with its priming-wires, and a sufficient quantity of powder, shot, crow, handspike, bed, quoin, train-tackle, &c. sending, without delay, for a supply of any thing that may be missing ; and for the greater certainty of not overlooking any deficiency, he is to give strict orders to every captain under him to make the like examination at his respective gun, and to take care that every requisite is in a serviceable condition, which he is to report accordingly. And besides the other advantages of this regula- tion, for the still more certain and speedy account of being taken upon these occasions, the midshipman is to give each man his charge at quarters, (as expressed in the form of the monthly report,) who is to search for his particular implements, and not finding them, is immediately to acquaint his captain, that upon his report to the midshipman they may be replaced. The man who takes care of the powder is to place himself on the opposite side of the deck from that where we engage, except when fighting both sides at once, when he is to be amid- ships. He is not to suffer any other man to take a cartridge from him, but he who is appointed to serve the gun with that article, either in time of a real engagement or at an exercise. Lanterns are not to be brought to quarters in the night, until the midshipman gives his orders for so doing to the person he charges with that article. Every thing being in its place, and not the least lumber in the way of the guns, the exercise begins with— 1st. Silence. At this word every one is to observe a silent attention to the officers. 2d. Cast loose your Guns. The muzzle-lashing is to be taken off from the guns, and (being coiled up in a small compass) is to be made fast to the eye-bolt above the ports. The lashing- tackles at the same time to be cast on, and the middle of the breechings seized to the thimble of the pomilion. The sponge E X E Te X H 295 DICTIONARY OF MECHANICAL SCIENCE. to be taken down, and with the crow, handspike, &c. laid upon the deck by the gun. When prepared for engaging an enemy, the seizing within the clinch of the breeching is to be cut, that the gun may come sufficiently within board for loading, and that the force of the recoil may be more spent before it acts upon the breeching. - , 3d. Level your Guns. The breech of your metal is to be seized so as to admit the foot of the bed's being placed upon the axle-tree of the carriage with the quoin upon the bed, both the ends being even one with the other. When levelled for firing, the bed is to be lashed to the bolt which supports the inner end of it, that it may not be thrown out of its place by the violence of the gun's motion when hot with frequent discharges. 4th. Take out your Tompions. The tompion is to be taken out of the gun's mouth, and left hanging by its laniard. 5th. Run out your Guns. With the tackles hooked to the upper bolts of the carriage, the gun is to be bowsed out as close as possible, without the assistance of crows or handspikes, taking care at the same time to keep the breeching clear of the trucks, by hauling it through the rings ; it is then to be bent so as to run clear when the gun is fired. When the gun is run out, the tackle-falls are to be laid alongside the carriages in neat fakes, that when the gun, by recoiling, overhauls them, they may not get foul, as they would if in a common coil. 6th. Prime. If the cartridge is to be pierced with the prim- ing wire, and the vent filled with powder, the pan also is to be filled, and the flat space, having a score through it at the end of the pan, is to be covered; and this part of the priming is to be bruised with the round part of the horn. The apron is to be laid over, and the horn hung up out of danger from the flash of the priming. 7th. Point your Guns. At this command the gun is, in the first place, to be elevated to the height of the object by means of the side-sights; and then the person pointing is to direct his fire by the upper sight, having a crow on one side, and a hand- spike on the other, to heave the gun by his direction till he catches the object. The men who heave the gun for pointing, are to stand between the ship s side, and their crows or hand- spikes, to escape the injury they might otherwise receive from their being struck against them, or splintered by a shot; and the man who attends the captain with a match is to bring it at the word “point your guns,” and kneeling upon one knee opposite the train-truck of the carriage, and at such distance as to be able to touch the priming, is to turn his head from the gun, and keep blowing gently upon the lighted match to keep it clear from ashes. And as the missing of an enemy in action, by neglect, or want of coolness, is most inexcusable, it is par- ticularly recommended to have the people thoroughly instructed in pointing well, and taught to know the ill consequences of not taking proper means to hit their mark; wherefore they should be made to elevate their guns to the utmost nicety, and then to point with the same exactness; and having caught the object through the upper sight, at the word 8th. Fire, The match is instantly to be put to the bruised part of the priming, and when the gun is discharged, the vent is to be closed, in order to smother any spark of fire that may remain in the chamber of the gun; and the man who sponges, is immediately to place himself by the muzzle of the gun is readiness, when, at the next word, 9th. Sponge your Gun, The sponge is to be rammed down to the bottom of the chamber, and then twisted round, to extinguish effectually any remains of fire ; and when drawn out, to be struck against the outside of the muzzle, to shake off any sparks or scraps of the cartridge that may have come out with it; and next its end is to be shifted ready for loading ; and while this is doing, the man appointed to provide a car- tridge is to go to the box, and by the time the sponge is out of the gun, he is to have it ready ; and at the word 10th. Load with Cartridge, The cartridge (with bottom end first, seam downwards, and a wad after it,) is to be put into the gun, and thrust a little way within the mouth, when the rammer is to be entered ; the cartridge is then to be rammed down, and the captain at the same time is to keep his priming- wire in the vent, and seeing the cartridge, is to give the word “home,” when the rammer is to be drawn, and not before. mer is to be entered as before. bowsing the lashing very taught, & | While this is doing, the man appointed to provide a shot is to provide one (or two, according to the order at that time,) ready at the muzzle, with a wad likewise; and when the rammer is drawn, at the word 11th. Shot your Guns, The shot, and wad upon it, are to be put into the gun, and thrust a little way down, when the ram- The shot and wad are to be rammed down to the cartridge, and there have a couple of forcible strokes, when the rammer is to be drawn, and laid out of the way of the guns and tackles, if the exercise or action is continued; but if it is over, the sponge is to be secured in the place it is at all times kept in. a . 12th. Put in your Tompions. the mnzzle of the cushion. 13th; Hºuse your Guns. The seizing is to be put on again upon the clinched end of the breeching, leaving it no slacker than to admit of the gun's being hoisted with ease. The quoin is to be taken from under the breech of the gun and the bed, still resting upon the bolt within the carriage, thrust under tiji the foot of it falls off the axletree, leaving it to rest upon the end which projects out from the foot. The metal is to be let down upon this. The gun is not to be placed exactly square, and the muzzle is to be close to the wood, in its proper place for passing the muzzle-lashings. 14th. Secure your Guns. The muzzle-lashings must first be made secure, and then with one tackle, having all its parts equally taught with the breeching, the gun is to be lashed. The other tackle is to be bowsed taught, and by itself made fast, that it may be ready to cast off for lashing a second breeching. Care must be taken to hook the first tackle to the upper bolt of the carriage, that it may not otherwise obstruct the reeving of the second breeching, and to give the greater length to the end part of the fall. No pains must be spared in that the guns may have the least play that is possible, as their being loose may be produc- tive of Yery dangerous consequences. The quoin, crow, and handspike, are to be put under the gun; the nowder horn hung up in its place, &c. º - “Being engaged at any time when there is a large swell, a rough sea, or in squally weather, &c. as the ship may be liable to be suddenly much heeled, the port tackle-fall is to be kept clear, and whenever the working of the gun will admit of it, the man charged with that office is to keep it in his hand; at the same time the muzzle lashing is to be kept fast to the ring of the port, and being hauled taught, is to be fastened to the eye-bolt over the port hole, so as to be out of the gun's way in firing, in order to haul it in at any time of danger. This pre- caution is not to be omitted when engaging to the windward, any more than when to the leeward, those situations being very subject to alter at too short a warning. A train tackle is always to be made use of with the lee guns, and the man stationed to attend it is to be very careful in preventing the gun's running out at an improper time. ExeRCISE may also be applied with propriety to the forming a fleet into order of sailing, line of battle, &c. an art which the French have termed evolutions or tactics. In this sense exer- cise may be defined the execution of the movements which the different orders and dispositions of fleets occasionally require, and which the several ships are directed to perform by means of signals. - EXHAUSTED ReceiveR, a glass, or other vessel, out of which the air hath been drawn by means of the air-pump. See PNEUMATICs. - EXHAUSTIONS, in Geometry. Method of exhaustions is a way of proving the equality of two magnitudes, by a reductio ad absurdum, shewing, that if one be supposed either greater or less than the other, there will arise a contradiction. The method of exhaustions was of frequent use among the ancient mathematicians, as Euclid, Archimedes, &c. It is founded on what the former says in his tenth book, viz. that those quan- tities whose difference is less than any assignable quantity, are equal; for if they were unequal, however small the difference might be, yet it might be so multiplied, as to become greater than eitherof them, and if not so, then it is really nothing. EXHIBIT, in Law, is where a writing, being produced in a chancery suit, the commissioner certifies on the back thereof, The tompions to be put into 2.96 B X P IE X P DICTIONARY OF MECHANIGA'L SCIENCE, that the same was shewn to the witness at the time of his “examination, and by him 'sworn to. - JEXHIBITION, a benefaction settled for the benefit of scho- lars in the universities, that are not on the foundation. EXIGENT, in Law, a writ which lies where the defendant -in a personal action cannot be found, nor any effects of his within the country, by which he may be attached or distrained. EXOCOETUS, or the FLYING Fish, in Ichthyology, a genus belonging to the order of abdominales. When pursued by another fish, it raises itself from the water by means of these 'fins, and flies in the air to a considerable distance, till the fins are dry, and then it falls down into the water. In its own relement it is perpetually harassed by the dorados and other fish of prey. If it endeavours to avoid them, by having recourse to the air, it either meets its fate from the gulls or the alba- tross, or is forced down again into the mouths of the inhabitants !of the water, who below keep pace with its ačrial excursions. This fish is most common between the tropics. .EXOTIC, an appellation for the produce of 'foreign coun- tries. Exotic plants of the hot climates are very numerous, ‘and require the utmost attention of the gardener. £XOTERIC and ESOTERIC, are terms denoting external and internal, and were applied to the double doctrine of the ancient philosophers, the former public and open, and the latter secret, or confined to a select number of disciples. EXPANSION, in Physics, is the enlargement or increase in the bulk of bodies, in consequence of a change in their tempe- rature. This is one of the most general effects of heat, being ‘common to all bodies whatever, whether solid or fluid. The ‘expansion of solid bodies is determined by the PYRoMeter, and that of fluids by the THERMoMETER. See these articles. The expansion of fluids varies considerably; but, in general, the denser the fluid, the less the expansion: thus, water ex- ‘pands more than mercury, and spirits of wine more than water; and commonly the greater the heat, the greater the expansion; but this is not universal, for there are cases in which expansion is produced, not by an increase, but by a diminution of temperature. Water furnishes us with the most remarkable instance of this kind. Its maximum of density corresponds with 42°.5 of Fahrenheit's thermometer, when cooled down below 429.5, it undergoes an expansion for every degree of temperature which it loses; and at 32° the expan- sion amounts to ºn of the whole expansion which water under- goes when heated from 42°.5 to 212°. With this, more recent 'experiments coincide very nearly ; for by cooling 100,000 parts in "bulk of water from 42°.5 to 32°, they were converted to 100,031 parts. The expansion of water is the same for any number of degrees above or below the maximum of density. Thus, if we heat water ten degrees above 42°.5, it occupies pre- cisely the same bulk as it does when cooled down ten degrees ‘below 429.5. Therefore the density of water at 32° and at 539 is precisely the same. Dalton cooled water to the tempera- ture of 59 without freezing, or 37°.5 below the maximum point of density; and during the whole of that range, its bulk pre- cisely corresponded with the bulk of water the same number of | degrees above 42°.5. te The prodigious force with which water expands in the act of freezing, is shewn by glass bottles filled with water, which are commonly broken in pieces when the water freezes. A brass globe whose cavity is an inch in diameter, may be burst by 'filling it with water and freezing it, and the force necessary for this effect is 27,720°this weight. The expansive force of freez- ing water may be explained, by supposing it the consequence of a tendency which water, in consolidating, is observed to ‘have to arrange its particles in one determinate manner, so as to form prismatic crystals, crossing each other at angles of, 60° and 120°. The force with which they arrange themselves in this manner must be enormous, since it enables small quan- tities of water to overcome so great mechanical pressures. This observation is conspicuously illustrated by observing the crys- tals of ice on a piece of water exposed to the action of the air in frosty weather; or upon a pane of glass in a window of a ‘room without a 'fire, at the same season. Various methods have been tried to ascertain the specific gravity of ice at 32°; that which succeeded best was to dilute spirits of wine with ‘water till a mass of solid ice put into it remained in any part of the liquid without either sińking or rising. The specifié | gravity of such a liquid is 0.92, which of course is the specifič gravity of ice, supposing the specific gravity of water at 60° to | be 1. This is an expansion much greater than water experi- ‘ences even when heated to 212°, its boiling point. We see from this, that water, when converted into ice, no longer ob- 'serves that equable expansion measured by Dalton, but under- ‘goes a very rapid and considerable augmentation of bulk. |EXPARTE, a term used in the Court of Chancery, when a commission is taken out and executed by one side or party | only: upon the other parties neglecting or refusing to join therein. EXPECTATION, in the Doctrine of Chances, is the value any prospect of prize or property depending upon the happen- ing of some uncertain event, the value of which in all cases is equal to the whole sum multiplied by the probability that the event on which it depends may happen. - EXPECTATION, in the Doctrine of Life Annuities, denotes that particular number of years which a life of a given age has an ‘equal chance of enjoying, or the time which a person of a given age may justly expect to live. But Simpson has shewn that this period does not coincide with that which writers on annuities call the expectation of life, except on a supposition of a uniform decrease in the probabilities of life; and Dr. Price adds, that even on this supposition it does not coincide with what is called the expectation of life, in any case of joint lives. See SURVIvo RSHIP. The expectation of life coincides with the sums of the present probabilities, that any single or joint life 'shall attain to the end of the first, second, third, &c. moments from this time to the end of their possible existence, or in case of survivorships, with the sum of the probabilities, that there shall be a survivor at the expiration of those periods. From which principles Dr. Price has shewn how Demoivre deduced his rules for determining the expectation of any given life. jº's Table of the Expectation of Life in London, is as IOIIOWS : - — —a-t *—A- -º- Age. Expectation.] Age. Expectation.}} Age. Expectation.}| Age. Expectation. 1. 27-0 21 28°3 41 || 19.2 61 | 12:0 2 32-0 22 27.7 42 18'8 62 11-6 3 34'0 23 27.2 43 || 18°5 63 11.2 4 35'6 24 26-6 44 18°1 64 10'8 5 36-0 25 26-1 45 17-8 65 10-5 6 36.0 26 25'6 46 17.4 66 10-1 7 35'8 27 25:1 47 17-0 67 9'8 8 35'6 28 24'6 48 16-7 68 9°4 9 || 35’2 || 29 || 24.1 || 49 || 16-3 || 69 9-1 10 34°8 30 || 23-6 50 || 16°0 70 8'8 11 34.3 31 23-1 51 15'6 71 S'4 12 || 33-7 32 22.7 52 15 2 72 8'1 13 33. I 33 22-3 53 I4-9 73 7-8 14 32°5 34 21.9 54 14'5 ’74 7-5 15 31°9 35 21.5 55 14°2 75 '7.2 16 31°3 36 21.1 56 13-8 76 6'8 17 || 30-7 37 20-7 57 13°4 77 6'4 18 30°]. 38 20-3 58 13-1 78 6-0 19 29.5 || 39 199 || 59 12.7 || 79 5.5 20 28.9 40 19:6 60 12°4 80 5.0 l } From this table, the expectation of life, at any age, is found on inspection; thus, a person of 20 years of age has an expec- tation of living 28.9 years, and in the same manner may be found the expectation at any other age. EXPECTORANTS, in Pharmacy, medicines which promote expectoration; such are the stimulating gums and resins, squills, &c. r EXPECTORATION, the act of evacuating or bringing up phlegm, or other matters, out of the trachea and lungs, by coughing, &c. BXPERIMENT, in Philosophy, is a trial of the effect or result of certain applications and motions of natural bodies, in -order to discover their natures, laws, relations, &c. EXPERIMENTAL, PHILosophy, is that which deduces the laws of nature, the properties and powers of bodies, and their E X , P: E X. T. 297 DICTIONARY OF MECHANICAL SCIENCE. actions upon each other, from sensible experiments and obser- vations. In our inquiries.into nature, we are to be guided by those rules and maxims which are found genuine, and conso- mant to a just method of physieal reasoning; and these rules are by Sir Isaac Newton reckoned four, viz. 1. More causes of natural things. are not to be admitted, than are true, and sufficient to explain the phenomena; for nature is simple, and does nothing in vain. 2. Therefore of natural effects of the same kind, the same causes are to be assigned, as far as it can be done; as of respiration in man and beasts, of the descent of stones in Europe and America, of light in a culinary fire and in the sun, and of the reflection of light in the earth and the other planets. 3. The qualities of natural bodies which cannot be increased or diminished, and agree to all bodies on which experiments can be made, are to be reckoned as the qualities of all bodies whatever; thus, because extension, divisibility, hardness, impenetrability, mobility, the vis inertia, and gravity, are found in all bodies under our inspection, we may conclude that they belong to all bodies whatever, and of which they are the original and universal properties. 4. In experimental philosophy, propositions collected from the phenomena by induction, are to be deemed (notwithstanding contrary hypo- theses) either exactly, or very nearly true, till other phaenomena occur, by which they may be rendered more accurate, or liable to exception. This ought to be done, lest argument of induc- tion should be destroyed by hypotheses, and logical series be superseded by conjectures. - ... • * - EXPERIMENTUMI, CRucis, a leading or decisive experi- ment, is so termed on account of its being like a cross, placed in the meeting of several roads, guiding men to the true know- ledge of what they are inquiring after; or on account of its being a kind of torture, whereby the nature of the thing is dis- covered by force. • - . . . - EXPLOSION, in Natural Philosophy, a sudden and violent expansion of an aérial or other elastic fluid, by which it instantly throws off any obstacle in its way. Explosion differs from expansion in this; that the latter is a gradual power, acting uniformly for some time, whereas the former is momentary. The expansions of solid substances do not terminate in violent explosions, on account of their slowness, and the small space through which the expanding substance moves. Thus we find, that though wedges of wood, when wetted, will cleave solid blocks of stone, they never throw them to any distance, as gunpowder does. On the other hand, it is seldom that the expansion of any elastic fluid bursts a solid substance, without throwing the fragments of it to a considerable distance. The reasons of this may be comprised in these particulars : 1. The immense velocity with which the aërial fluids expand, when affected by a considerable degree of heat. 2. Their celerity in acquiring heat, and being affected by it, which is much superior to that of Solid substances. Thus air, heated as much as iron when brought to a white heat, is expanded to four times its bulk: but the metal itself will not be expanded the 500th part of that space. In the case of gunpowder, the velocity with which the flame moves is calculated by Mr. Robins, to be no less than 7000 feet in a second, or little less than 70 miles per minute. Hence the impulse of the fluid is inconceivably great, and the obstacles on which it strikes are carried off with vast velocity, though much less than that just mentioned; for a cannon-ball, with the greatest charge of powder, does not move at a greater rate than 2400 feet per second, or little more than 27 miles per minute. The velocity of the ball again is promoted by the sudden propagation of the heat through the whole body of the air, as soon as it is extricated from the materials of which the gunpowder is made, so that it is enabled to strike all at once, and thus greatly to augment || the movements of the ball. We may conclude, upon these principles, that the force of an explosion depends, 1. on the the quantity of elastic fluid to be expended; 2, on the velocity it acquires by a certain degree of heat; and 3. on the cele- rity with which the degree of heat affects the whole of the expansile fluid. These three take place in the greatest perfec- tion where the electric fluid is concerned, as in lightning, earth- quakes, and volcanoes. See STEAM. EXPONENT, in Algebra, a number placed over any power Ol' in-gyed quantity, to shew to what height the root is raised; 3: - - * e thus the number 2 is the exponent of aº, and 4 the exponent of a ', or a ſa, a ar. EXPORTATION, in Commerce, the art of sending goods out of one country into another. - EX POST FACTO, in Law, something done after another; thus, a law is said to be ea post facto when it is enacted to punish an offence committed before the passing of the law; a violation of the plainest principles of justice. EXPRESSED OILS, in Chemistry, are those which are obtained from bodies only by pressing, to distinguish them from animal and essential oils, which last are for the most part obtained by distillation. . . - + EXTENSION, in Philosophy, one of the common and essen- tial properties of body, or that by which it possesses or takes up some part of universal space. - - EXTENT, in Law, signifies a writ or command to the sheriff, for the valuing of lands or tenements; and sometimes the act of the sheriff, or other commissioner, upon this writ; but most commonly it denotes an estimate or valuation of lands, and hence come our extended or rack rents. EXTERMINATION, in general, the extirpating or destroy- ing something. In Algebra, surds, fractions, and unknown quantities, are exterminated by the rules observed for reducing equations. - EXTRA JUDIC:AL, in Law, is when judgment is given in a cause or case not depending in that court where such judg- ment is given, or wherein the judge has no jurisdiction, or legal authority. - - - - - - * * ExTRA: Parochial, out of any parish; privileged or exempted from the duties of a parish. - EXTRACT, in Pharmacy, is a solution of the purer parts of a mixed body inspissated, by distillation or evaporation, nearly to the consistence of honey. EXTRACT, exists in almost all plants, and consists principally of astringent matter, and extract; by the action of water upon it, the astringent matter is first dissolved, and may be sepa- rated from the extract. Extract is always more or less coloured; it is soluble in alcohol and water, but not soluble in ether. It unites with alumina when that earth is boiled in a solution or extract; and it is precipitated by the salts of alu- mina, and by many metallic solutions, particularly the solution of muriate of tin. From the products of its distillation, it seems to be composed principally of hydrogen, oxygen, carbon, and a little azote. - º fºXTRACTION of the SQUARE Root. Extracting the Square root is to find out such a number as, being multiplied into itself, the product will be equal to the given number. Rule 1. Point the given number, beginning at the unit's place, then to the hundreds, and so upon every second figure through- out. 2. Seek the greatest square number in the first point towards the left-hand, placing the square number under the first point, and the root thereof in the quotient; subtract the square number from the first point, and to the remainder bring down the next point, and call that the Resolvend. 3. Double the quotient, and place it for a divisor on the left-hand of the resolvend; seek how often the divisor is contained in the resolvend, (preserving always the unit’s place,) and put the answer in the quotient, and also on the right-hand side of the divisor; then multiply by the figure last put in the quotient, and subtract the product from the resolvend; bring down the next point to the remainder, (if there be any more ) and pro- ceed as before. IRoots, T. 2. 3. 4. 5. 6. 7, 8, 9. Squares, 1. 4. 9. 16. 25. 36. 49. 64, 81. Example. What is the square root of 1 19025? - 119025 (345 Ans. 9 64);90 × - ? 256 685)3425 3425 sºmºsºmº- 398 E. Y. E. B, X. Tº piction ARY OF MECHANICAL SCIENGE. To Extract the Square Root of simple Algebraic Quantities.-- Extract the root of the co-efficient for the numerical part, and divide the index of the letter, or letters, by the exponent of the proposed root, and it will give the answer required. Thus the 'square root of 92% = 32 = 3 w; and the cube root of 8 acº - 2 a. - To find the Root of Compound Quantities, proceed as in com- mon arithmetic, ranging the quantities according to the dimen- sions of one of the letters, and proceed as under: Fr.:1. Extract the square root of acº — 42* + 6 a.” —4a: + 1. a' — 42% -- 6 a.” — 42 + 1 (2% — 22, -ī- 1 = root acº . 222 – 2a) – 4 a.” + 6 a.” – 4 acº —H 4 a.” - 22° — 42 + 1) 22 — 42 + i ... • 2a:” – 4 a + 1 2. Extract the square root of 4a' + 12a3a + 13a*a* + 6 aw”--a: 4a: -- 12a3a + 13 a'a' + 6 a.a.” -- a-- (2a2 + 3 ga' + æ” 4 as 4a2 + 3 a.a.) 12a3a; + 31, a2a:” - 12 as a: + 9 a.2 ac” 4 a” + 6 a.a. -- wº)4 aº -- 6aas -- ** 4 a” ac2 + 6 a. a.3 + æ" To find the Roots of Powers in general.—Find the root of the first term, and place it in the quotient; subtract its power from that term; then bring down the second term of the divi- dend. Involve the root, last found, to the next lowest power, and multiply it by the index of the given power for a divisor; divide the dividend by this divisor, and the quotient will be the next term of the root. Involve now the whole root, and subtract and divide as before ; and so on till the whole is finished. Ex. 1. Required the square root of a -2a3a +3a*a*—2aa’-- a.º. - a' – 2 as a + 3 a” a.”— 2 aas -- a-- (a" – a a + a.º. ał 2 a.2) — 2 as a: a' — 2 as a + a 2 x = (a” — a 2)” 2 a.2) 2 a” wº a' — 2 as a + 3 a” a." — 2 a cº -- a-- = (a” — a a + æ2)? Ex. 2. Extract the cube root of a " + 625 – 40 a.3 + 96 a = 64. a" + 6aº — 40 a.” + 962 – 64 (22 + 2a – 4 26 3 wº) 62.5 as + 633 + 12 r + 8wº = (x + 2 a.) 3a*) – 12 a." as + 625 – 40 as + 96 a – 64 = (a,” + 2 x – 4). Extraction of the Cube Root. To extract the cube root is to find out a number, which being multiplied into itself, and then into that product, produceth the given number. Rule 1. Point every third figure of the cube given, beginning at the unit’s place; seek the greatest cube to the first point, and sub- tract it therefrom ; put the root in the quotient, and bring down the figures in the next point to the remainder for a resolvend. 2. Find a divisor, by multiplying the square of the quotient by 3. See how often it is contained in the resolvend, rejecting the units and tens, and put the answer in the quo- tient. 3. To find the subtrahend. 1. Cube the last figure in the quotient. 2. Multiply all the figures in the quotient by 3, except the last, and that product by the square of the last. 3. Multiply the divisor by the last figure: Add these products to- gether, and they will give the subtrahend ; which subtract from the resolvend; to the remainder bring down the next point, and proceed as before. Roots. 1. 2, 3, 5, 6, 7, 8, 9. Cubes. 1. 8. 27. 125. 216. 343. 512. 729. Example. What is the cube root of 99.252847?, . 99232847(463 Divisor, 64 = cube of 4. Square of 4 × 3 = 48) 35252 resolvend. 216 = cube of 6. . 432 = 4 × 3 × by square of 6. 288 = divisor x by 6 Divisor, 88386 subtrahend. *ms Square of 46 x 3 = 6348) 1916847 resolvend. 27 = cube of 3. 1242 =46 × 3 × by square of 3. 19044 = divisor x by 3. - 1916847 subtrahend. A more Concise Method of Extracting the Cube Root.—Rule 1. Point every third figure of the cube given, beginning at the unit's place, then find the highest cube to the first point, and subtract it therefrom, put the root in the quotient, bring down the figures in the next point to the remainder for a resolvend.— 2. Square the quotient, and triple the square for a divisor. As 4 × 4 × 3 = 48. Find how often it is contained in the resolvend, rejecting units and tens, and put the answer in the quotient.—3. Square the last figure in the quotient, and put it on the right-hand of the divisor. As 6 x 6 = 36 put to the divisor 48 = 48 36.—4. Triple the last figure in the quotient, and multiply by the former, put it under the other, units under the tens, add them together, and multiply the sum by the last figure in the quotient, subtract that product from the resolvend, bring down the next point, and proceed as before. Example. What is the cube root of 99.252847? The square of 4 × 3 = 48 divisor. 9923284% (463 The square of 6 put to 48 = 4836 64 * . 6 × 3 × 4 72a: 35252 5556 × 6 = 3336 1916847 The square of 46 = 2116 x 3 = 6348 divisor. The square of 3 = 9 put to 6348 = 634809 3 × 3 × 46 – 414 638949 × 3 = 1916847 Hence the cube root of 99252847 = 463 for 463 × 463 × 463 = 99252847 Another, and a very simple method of extracting the cube root, is as follows: Point off the given number in periods of three figures, beginning at the unit’s place. Find the root of the last period, i. e. the period on the left-hand side of the number; subtract this root, as in the following example, where 64 is taken from 99; to the remainder 35 bring down the next period 252, and seek a divisor by multiplying the . Square of the quotient 4 (i.e. 16) by 300, and the product 4800 will be the new divisor, which is contained in 35252 six times; set this 6 in the quotient. Bring down the two periods 99 and 252 into one sum 99252; now cube the quotient 46, and place its product 97336 under the dividend; subtract the cube from this dividend, and to the remainder 1916, bring down the next period in the dividend, viz. 847; square the quotient 46, mul- tiply this square by 300 for a divisor, find how often, it is, con- tained in 1916847, viz. three times; set this 3 in the quotient. Bring down the whole dividend 99,252,847, cube the quotient 463, and subtract its product as before, and so on till the divi- dend is exhausted :- * & R Y F. R Y E 299 DICTIONARY of MBUHANICAL science. Thus : '99|252,847(463 * 64 - 42 x 300 = 4800 35252 (6 28800 99.252 463 - 97336 46' x 300 = 634800 1916847 (3 1904400 ~ 99.252847 463 = 99252847 EXTRACTOR, in Midwifery, an instrument, or forceps, for extricating children by the head. EXTRADOS, the outside of an arch of a bridge, vault, &c. See BRIDGE, EXTRAVASATION, in contusions, and other accidents of the cranium, is when one or more of the blood-vessels distri- buted on the dura mater, are broken, whereby there is such a discharge of blood as oppresses the brain, frequently bringing on violent pains, and at length death itself, unless the patient is timely relieved. EXTREME and MeAN PRoPortional. See Proportional. EXTREMES, CoNJUNCT and Disjunct, in Spherical Trigo- mometry, are, the former, the two circular parts that lie next the middle part, and the latter, the two that lie remote from the middle part. These were the terms applied by Napier in his universal theorem, commonly called Napier's Circular Parts. EXUVIAE, among naturalists, denotes the cast-off parts or coverings of animals, as the skins of serpents, caterpillars, and other insects. - . EYE, the organ of sight, consisting of several parts, so adapted to each other as to answer the purpose of distinct vision when placed in a proper situation with regard to light and shade. The eye, though properly a subject of anatomy, is so connected with the doctrine of vision, that its structure must first be understood before any advances can be made in that theory, and as such it becomes a matter of philosophical inquiry and must not therefore be wholly omitted in the pre- sent work, although our limits will only admit of a brief illus- tration of its construction and principal mode of operation. The annexed figure represents - - a section of the human eye, made by a plane, which is per- pendicular to the coats which contain its several humours, and also to the nose. Its form is nearly spherical, and would be exactly so, were not the forepart a little more convex than the remainder; the parts B F B, BA, B, are, in reality, segments of a greater and less sphere. The humours of the eye are contained in a firm coat B F, B.A. called the sclerotica; the more convex or protube- rant part of which, B A B, is transparent, and, from its con- sistency and horny appearance, it is called the cornea. This coat is represented by the space contained between the two exterior circles B F, B.A. Contiguous to the sclerotica is a second coat, of a softer substance, called the choroeides; this coat is represented by the next white space, and extends along the back part of the sclerotica to the cornea. tion of the choroeides and cornea, arises the uvea, Ba, Ba, a flat opaque membrane, in the forepart of which, and nearly in its centre, is a circular aperture called the pupil. The pupil is capable of being enlarged or contracted with great readiness; by which means, a greater or less number of rays may be admitted into the eye, as the circumstances of vision require. In weak light, too few rays might render objects indistinct; and in a strong light, too many might injure the organ. Whilst the pupil is thus enlarged or contracted, its figure remains unaltered. This remarkable effect is thought to be produced by means of small fibres which arise from the outer circumfe- rence of the uvea, and tends towards its centre; this circum- From the junc- | ference is also supposed to be muscular, and by its equal action upon the fibres, on each side, the form of the pupil is preserved, whilst its diameter is enlarged or contracted: At the back part of the eye, a little nearer to the nose than the point which is opposite to the pupil, enters the optic nerve V, which spreads itself over the whole of the choroeides like a fine net, and from this circumstance is called the retina. It is immersed in a dark mucus, which adheres to the choroeides. These three coats, the sclerotica, the choroeides, and the retina, enter the socket of the eye at the same place. The sclerotica is a continuation of the dura mater, a thick membrane which lies immediately under the scull. The choroeides is a con- tinuation of the pia mater, a fine thin membrane which adheres closely to the brain. The retina proceeds from the brain. Within the eye, a little behind the pupil, is a soft transpa- rent substance, E D E, nearly of the form of a double convex lens, the anterior surface of which is less curved than the pos- terior, and rounded off at the edges, E, E, as the figure repre- Sents. This humour, which is nearly of the consistency of a hard jelly, decreasing gradually in density from the centre to the circumference, is called the crystalline humour. It is kept in its place by a muscle called the ligamentum ciliare, which takes its rise from the junction of the choroeides and cornea, and is a little convex towards the uvea. The cavity of the eye, between the cornea and crystalline humour, is filled with trans- parent fluid like water, called the aqueous humour. The cavity between the crystalline humour and the back part of the eye, is also filled with a transparent fluid, rather more viscous than the former, called the vitreous humour. It is not easy to ascertain, with great accuracy, the refract- ing powers of the several humours; the refracting powers of the aqueous and vitreous humours are nearly equal to that of water; the refracting power of the crystalline humour is some- what greater. The surfaces of the several humours of the eye are so situated as to have one line perpendicular to them all. This line, A D F, is called the axis of the eye, or optic aris. The focal centre of the eye, is that point in the axis at which the image upon the retina and the object subtend equal angles, This point is not far distant from the posterior surface of the crystalline lens, though its situation is probably subject to a small change, as the figure of the eye, or the distance of the object, is changed. - From the consideration of the structure of the eye, we may easily now understand how the notices of external objects are conveyed to the brain. Let PQ R, in the annexed figure, be an object, towards which the axis of the eye is directed; then the rays which diverge from any point Q, and fall upon the convex surface of the aqueous humour, have a degree of con- vergency given them; they are then refracted by a double convex lens, denser than the am- bient mediums, which increases the convergency; and if the extreme rays Q H, Q I, have a proper degree of divergency before incidence, the pencil will be again collected upon the retina, at q, and there form an image of Q. In the same man- ner, the rays which diverge from any other points, P, R, in the object, will be collected at the corresponding points, p, r, of the retina, and a complete image, p, q, r, of the object P Q R, will be formed there. The impression thus made, is conveyed to the brain by the optic nerve, which originates there, and is evidently calculated to answer this purpose. - - Here it will be observed, that since the axis of the several pencils cross each other at O, the focal centre of the eye, the image upon the retina is inverted with respect to the object, and yet it furnishes, the mind with the idea of its being erect. This is a difficulty that has produced considerable discussion amongst philosophers, and the most satisfactory explanation which can probably be given is, that experience alone teaches us what situation of an external object corresponds to a particular impression upon the retina. Some opticians, however, are unwilling to concede this point, and contend that the object is reſlected from the retina to another substance on which they are painted, and thus give to the eye exactly the construction of a Gregorian telescope. E. Y. E . E Y E DICTIONARY OF MECHANICAL SCIENCE The following measure of the crystalline and cornea, were taken by Dr. Gordon and Dr. Brewster, from the eye of a female above 50 years of age, a few hours after death. Diameter of the crystalline,... . . . . . . . . ........ 0-378 Diameter of the cornea, . . . . . . . . . . . . . . . . . . . . 0°400 Thickness of the crystalline, . . . . . . . . . . . . . . . . . . 0°l 72 Thickness of the cornea, . . . . . . . . . . . . . . . . • - - - - 0.042 Measures of the refractive powers of the humours of the Same eye:— e - Index of Refrac{ion. Refractive power of water,. . . . . . . . . . . . . . . . . . ... 1-3358 Ditto, of aqueous humour,. . . . . . . . . . . . . . . . . . 1°3366 Ditto, of vitreous humour, . . . . . . . . . . . . . . . . . . 1°3394 Ditto, of outer coat of crystalline, . . . . . . . . . . ... l'3767 Ditto, of middle coat of ditto, . . . . . . . . . . . . . . . 1' 3786 Ditto, of central part of ditto, . . . . . . . . . . . . . . . 1 3990 Ditto, of the whole crystalline,. . . . . . . . . . . . . . 1°3839 The range of the eye, or the field of vision, may be taken at 110 degrees. - t Eye, in Architecture, is used to signify any round window made in a pediment, an attic, the reins of a vault, or the like. Eye of a Dome, an aperture at the top of a dome, as that of the Pantheon at Rome, or of St. Paul's at London: it is usually covered with a lantern. Eye, in Agriculture, and Gardening, signifies a little bud, or shoot, inserted into a tree by way of graft. Eye of a Tree, a small pointed knot to which the leaves stick, and from which the shoots or sprigs proceed. . . . . . . Eye of a Block Strop, is that part by which it is fastened or suspended to any particular place upon the sails, masts, or rigging; the eye is sometimes formed by making two eye- splices on the ends of the strop, and then fastening them toge- ther with a small line, so as to bind round a mast, yard, or boom, as is deemed necessary. • Eye of a Stay, that part of a stay which is formed into a sort of collar to go round the mast-head. . Flemish Eye, is a phrase particularly applied to the eye of a stay, which is either formed at the making of the rope, or by dividing the yarns into two equal parts, knotting each pair | separately, and pointing the whole over. fy E-Bolt, a ſong bar of iron, with an eye in one end of it, formed to be driven into the decks, sides, &c. for the purpose of fastening ropes, or hooking tackles to. Eyes of a Ship, a name frequently given to those parts which lie near the hawse holes, particularly in the lower apartments within the vessel. * EYELET Holes, round holes worked in a sail, to admit a small rope through, chiefly the robins (or rope-bands), and the points or reef-line. - F. F A c F, the sixth letter of the Alphabet. As a numeral it denotes 40, and with a dash over it thus F 40,000. In Music it stands for the bass-clef, and frequently for forte, as # does for forte forte. F, in Medicine, stands for fiat, let it be done. FA, in Music, one of the syllables invented by Guido Are- time, to mark the fourth note of the modern scale which rises thus, ut, re, mi, fa. Musicians distinguish two fa’s, viz. the flat, marked thus to ; the sharp, marked thus # ; and the natural, marked thus a ; and called biquadro. Fa finto, a feigned F, or a feint upon that note. . FABLE, a tale or feigned narration, designed either to instruct or amuse, disguised under the allegory of an action. FABLE is also used for the plot of an epic or dramatic poem ; and is, according to Aristotle, the principal part, and the soul of a poem. . - FACE of A Stone, in Masonry, that superficies of it which lies in the front of the work. The workmen generally chuse to make one of those sides the face, which, when in the quarry, lay perpendicularly to the horizon, and consequently the break- ing, not the cleaving way of the stone. FACET, or FACETTE, among jewellers, the name of the little faces or planes in brilliant and rose diamonds. - | FACTITIOUS, any thing made by art, in opposition to what is the produce of nature. Thus, factitious cinnabar is opposed to native cinnabar. - FACTOR, in Arithmetic, a name given to the multiplier and multiplicand, because they constitute the product. FACTOR, in Commerce, an agent employed by a merchant or merchants, to sell goods, or buy goods, at some remote or foreign place, and to negotiate bills, &c. upon a certain fixed allowance or commission. The supercargo and factor differ in this; the supercargo takes care of goods which he accompanies to some destined place, and then returns to his employers: The factor resides abroad, and executes business for different merchants. But their duties, and the circumstances for which they are accountable, are the same. They procure the best intelligence of the markets; execute their business with all the despatch possible; are punctual in their correspondence; act under absolute or limited power; but it is incumbent on the employer, if he challenge his factor's proceedings, to prove that he could himself have done better. And a factor is never warranted to deal or trust with any persons, unless allowed t F A G by his employers, and with persons of good credit. In case of bankruptcies, a factor can lay attachments, and advise his employers thereof. Goods seized through his negligence, he must pay for. If a factor become insolvent, his employers, not his creditors, recover the prices of all goods sold by him for the said employers. There are various other duties too tedious to mention, which belong to the office of factor, and which can only be known from practice. • , a FACTORAGE, called also Commission, is the allowance given by merchants to the factors whom they employ. In Britain it is about 24 per cent; in Italy 2% ; in Spain, France, Holland, Dantzic, Portugal, 2 per cent. ; in Turkey, 3 per cent. ; in North America 5 per cent. on sales, and 5 per cent. on returns. In the West Indies 8 per cent on sales and storage, &c. FACTUM, is the product arising from the multiplication of several factors; thus 35 is the factum of 5 times 7. FACULTY, a privilege granted to a person doing what, by law, he ought not to do. For granting these privileges, there is a court under the archbishop of Canterbury, called the court of the faculties. i . FACULTY, in the Schools, a term applied to the different mem- bers of an university, according to the arts and sciences taught there ; as 1. Arts. 2. Theology. 3. Physic. And 4. Civil Law. FACULTY of Advocates, a term applied to the college or society of advocates in Scotland, who plead in all actions before the Court of Session. They meet in the beginning of every year, and choose the annual officers of the society, viz. dean, treasurer, clerks, private and public examinators, and a curator of the library. FA culty is also used to denote the powers of the human mind, viz. understanding, will, memory, and imagination. FAECES, in Chemistry, the gross matter, or sediment, that settles at the bottom after distillation, fermentation, &c. FAGARA, Ironwood, a genus of the monogynia order, in the tetandria, class of plants, and in the natural method rankling under the 43d order, dumose. There are 10 species, all natives of America, rising with woody stems more than 20 feet high. FAGNANO, JULes CHARLEs, a distinguished Italian mathe- matician, born about the year 1690, early in the eighteenth century published several memoirs, in the Italian journals, on the transcendental analysis; there are also many pieces of the same author in the Leipsic Acts, which were afterwards pub- F A L F A L. DICTIONARY OF MECHANICAL SCIENCE, 301 lished by himself, with some other papers, under the title of “Mathematical Productions;” Pesaro, 4to. 1750. FAGUS, the Beech Tree, a genus of the polyandria order in the monoecia class of plants; and in the natural method rank- ing under the 50th order, amentaceae. There are five species. The most remarkable are; 1. The sylvatica, or beech tree, which rises 60 or 70 feet high, and has a proportionable thick- mess. 2. The castanea, or chestnut tree, has a large upright trunk growing 40 or 50 feet high. 3. The pumila, dwarf chest- nut tree, or chinkapin, rises eight or ten feet high. FAIR, a greater kind of Market granted to a town, by privilege, for the more speedy and commodious buying and selling, or providing such things as the place stands in need of. It is incident to a fair, that persons should be free from being arrested in it for any debt, except that which has been con- tracted in the same ; or, at least, promised to be paid there. These fairs are usually held twice a year, in some places only once a year; and by statute, they shall not be held longer than they ought by the lords thereof, on pain of their being seized into the king's hands, &c. Also proclamation is to be made, how long they are to continue; and no person shall sell any goods after the fair is ended, on forfeiture of double the value, one-fourth to the prosecutor, and the rest to the king. There is a toll usually paid at fairs, for the privilege of erecting stalls from which to sell goods, as well as booths, either for enter- taiment or pastime. FAIR, a general term for the disposition of the wind when it is favourable to a ship's course, in opposition to what is con- trary or foul. This term, when applied to the wind, is much more comprehensive than Large, since the former seems to include about eighteen points of the compass, or at least six- teen, whereas Large is confined to the beam or quarter, that is, to a wind which crosses the keel at right angles, or obliquely from the stern, but never to one right astern. See the articles LARGE and ScANT. - - ... FAIR Curve, in delineating ships, is a winding line, whose shape is varied according to the part of the ship it is intended to describe. This curve is not answerable to any of the figures of conic sections, although it occasionally partakes of them all. FAIR Way, the channel of a narrow bay, river, or harbour, in which ships usually pass in their way up and down; so that if any vessels are anchored therein, they are said to lie in the fair way. FAIRY CIRCLE, or RING, a phenomenon frequent in the fields, &c. supposed by the vulgar to be traced by the fairies in their dances: there are two kinds, one of about seven yards in diameter, containing a round bare path a foot broad, with green grass in the middle of it. The other is of different bigness, encom- passed with a circumference of grass, greener and fresher than that in the middle. Some attribute them to lightning; and others to a kind of fungus which breaks and pulverizes the soil. FAKE, one of the circles or windings of a cable or hawser, as it lies disposed in a coil. The fakes are greater or smaller, in proportion to the extent or space which a cable is allowed to occupy where it lies. . FALCADE, in the Manege, the motion of a horse when he throws himself upon his haunches several times in very quick eurvets, which is done in forming a stop and half stop. FALCATED, horned, as the moon in the 1st and 3d quarter. FALCO, a genus of birds belonging to the order of acci- pitres. The eagle, kite, and hawk, form this genus; of which there are 32 species. 1. The leucocephalus, bald, or white- headed eagle, is ash-coloured, with head and tail white. 2. The ossifragus, sea-eagle, or osprey, with yellow wax, and half-feathered legs, is about the size of a peacock; the feathers are white at the base, iron-coloured in the middle, and black at the points; and the legs are yellow. 3. The charysaetos, or golden eagle, weighs about twelve pounds, and is in length about three feet, the wings when extended measuring about seven feet four inches. The sight and sense of smelling are very acute: the head and neck are clothed with sharp-pointed feathers, of a deep brown colour, bordered with tawny ; the hind part of the head in particular is of a bright rusty colour. 4. The cyaneus, or hen-harrier, with white wax, yellow legs, a whitish-blue body, and a white ring round the eyes and throat. 5. The albicilla, or cinereous eagle, is inferior in size to the golden eagle; the head and neck are of a pale ash-colour, the body and wings cinereous, coloured with brown; the quill feathers very dark; the tail white; the legs feathered but little below the knees, and of a very bright yellow. 6. The macula- tus, or crying eagle, is in colour of a ferruginous brown; the coverts of the wings and scapulars are varied with white spots; the primaries dusky, the ends of the greater white; the breast and belly of a deeper colour than the rest of the plumage, streaked with dull yellow ; the tail is dark brown, tipt with dirty white; the legs are feathered to the feet, which are yellow. The length of the bird is two feet. 7. The milvus, or kite, is a native of Europe, Asia, and Africa. This species generally breeds in large forests or woody mountainous countries. Its nest is composed of sticks, lined with rags, bits of flannel, rope, and paper. Its motion in the air distinguishes it from all other birds, being scarcely perceptible. Sometimes it will remain quite motionless for a considerable space; at others, glide through the sky without the least apparent action of its wings. They inhabit the north of Europe, as high as Jalsberg, in the South of Norway. 8. The gentilis, or gentil falcon, inhabits the north of Scotland, and was in high esteem in the days of falconry. 9. The subbuteo, or hobby, was used in falconry; particularly in what was called daring of larks. 10. The buteo, or buzzard, the most common of the hawk kind in England, breeds in woods, and usually builds on an old crow’s nest, which it enlarges, and lines with wool and other soft materials. 11. The tinnunculus, or kestrel, breeds in the hollows of trees, in the holes of high rocks, towers, and ruined buildings. 12. Heliaetus, the fishing-hawk of Catesby, called the osprey, mea- sures, from one end of the wing to the other, five feet and a half, is a species of vast quickness of sight; and will see a fish near the surface from a great distance, descend with rapidity, and carry the prey with an exulting scream high into the air. The bald eagle hears the note, and instantly attacks the hawk, who drops the fish, which the former catches before it can reach the ground or water. Besides these, there are some other species distinguished by ornithologists, but which it is unnecessary to particularize here. - FALCONRY, the exercise of taking wild fowl by means of hawks. The falcons or hawks that were in use in these king- doms are now found to breed in Wales, and in North Britain and its isles. The peregrine falcon inhabits the rocks of Caer- marvonshire. The same species, with the gyr-falcon, the gentil, and the gos-hawk, are found in Scotland, and the lanner in Ireland. This diversion, though very ancient, and in such high request, that many of the gentry and mobility hold their estates of the crown on condition of supplying the king with hawks, is now disused. FALLING STAR, in Meteorology, a phenomenon that is fre- quently seen, and which has been usually supposed to depend on the electric fluid. Sir Humphrey Bavy, in a lecture deli- wered at the Royal Institution, gave many reasons against this , opinion: he conceives that they are rather to be attributed to falling stones. It is observable, that when their appearance is frequent, they have all the same direction; and it has been remarked, that they are the forerunners of a westerly wind in our country. FALLOPIAN TUBEs, in Anatomy, are two ducts arising in the womb, one on each side of the fundus, and thence extended to the ovaries: these have their name from their resemblance to a trumpet, and that of Gabriel Fallopius, a physician of Italy, in the 16th century, who is reported to have first ascer- tained the use and office of these tubes. FALLOW LAND, is ground that has been left untilled for a time, in order that it may recover itself from an exhausted state; but to render a barren soil fertile, it ought to be fre- quently turned up to the air, and to have mixed with it manures of animal dungs, decayed vegetables, lime, marl, sweepings of streets, &c. In turning over the soil, the chief implements of the gardener are the spade, the hoe, and the mattock; and those of the farmer, are the plough, the har- row, the roller, the scythe, and the sickle. And as a succes- sion of the same crops tends to impoverish the soil, a rotation of different crops is necessary. Potatoes, grain, and white crops, are exhausting; but after them, the soil is ameliorated by tares, turnips, and green or plant crops. On stiff soils, * 4 H 302 F A T F A T DICTIONARY OF MECHANICAL SCIENCE. clover, beans, wheat, cabbages, and oats, may be cultivated in succession; and on light soils, potatoes, turnips, pease, oats, and barley, may succeed each other. The general rule is, one crop for man, and one for beast. This plan of varying the crops is a new discovery. Formerly, land lay long in fallow ; that is to say, was not worked every third or fourth year; but now it is usual, by varying the crops, to get two, three, or four, crops in a year from the same soil, without its being exhausted; and fallowing is, consequently, found to be unnecessary. FALSETTO, that species of voice in a man, the compass of which lies above his natural one, and is produced by constraint. FALSE IMPRIs on MeNT, in Law. To constitute the injury of false imprisonment, two points are necessary; the detention of the person, and the unlawfulness of such detention. Every confinement of the person is imprisonment, whether in a com- mon prison, or a private house, or even by forcibly detaining one in the streets or highways. FARINA Foecun DANs, in Botanical language, the dust on the apices or antherae of flowers, which being received into the pistil, or seed-vessel of plants, fecundates the rudiments of the seeds in the ovary, which would otherwise come to nothing. FARM, a Messuage, or district containing house or land, with other conveniences, hired or taken by lease, either in writing or parole, under a certain yearly rent. Farms vary in size, from fifty to one thousand acres. Arable farms are gene- rally smaller than those employed in pasture, or grazing. These, from two to four hundred acres, are the most beneficial to the occupiers and the public. Farmers are called arable farmers, when they are chiefly employed in raising corn; and pasture or grass farmers, when they are engaged in rearing and fattening sheep, and other live stock. Farms are either laid out according to the taste of the owners or occupiers, in all the simplicity of pastoral poetry; or in such an assortment of tillage, arable land, woods, coppices, &c. as convey a distinct notion of the pure Arcadian demesne ; or as a simple farm laid out with a sufficient adaptation of wood and water, of arable and pasture land, outhouses, cottages, and other improvements suggested by extensive or contracted enclosures, as may exhibit the good English farm. But to form an idea of an ornamented farm, Wooburn farm, near Weybridge, in Surrey, which brings every rural circumstance and appendage within the verge of a garden, ought to be seen. FARRIERY, the art of shoeing horses and curing their diseases; though the word veterimarius, horse doctor, would be more applicable to the veterinary art. See Horse. FARTHING, the fourth part of a penny; originally the fourth thing, or the fourth in the integer one penny. FARQUHAR,GeoRGE, an ingenious poet and dramatic writer, the son of an Irish clergyman, was born at Londonderry in 1678. FASCIAE, in Astronomy, certain parts on Jupiter's body resembling belts or swaths. They are more lucid than the rest of that planet, and are terminated by parallel lines, sometimes broader, and sometimes narrower. FASCINES, in Fortification, faggots of small wood of about a foot diameter, and six feet long, bound in the middle, and at both ends. & FASCIOLA, in Zöology, the Fluke or Gourd Worm; a genus of insects of the order of vermes intestina, of which there are several species, as the hepatica, or liver fluke, which bears some resemblance to the seed of the common gourd, and is found in fresh waters, ditches, at the roots of stones, sometimes in the intestines, and often in the substance of the other viscera in quadrupeds. - FASHION PIeces, the aftmost or hind most timbers of a ship, which terminate the breadth, and form the shape of the stern; they are united to the stern post, and to the extremity of the wing transom by a rabbet, and a number of strong nails or spikes driven from without. FASTI, in Roman Antiquity, the calendar wherein were expressed the several days of the year, with their feasts, games, and other ceremonies. FAT, animal oil, in its concrete substance, deposited in different parts of animal bodies. Many causes contribute to dissolve the fat in animals, as intemperature of the body, labour of mind, violent exercise, scanty diet, &c.; and rest, ease, sleep, plentiful food, generate fat. Larks and ortolans will fatten in 24 hours. To obtain fat pure, it must be cut in pieces, and cleaned from the interposed membranes and ves- sels; then cleaned from its gelatinous matter by water; after- wards melted with a little water, and kept in a fluid state till the water has entirely evaporated, which is known by the dis- continuance of the boiling, for the water alone causes it to appear boiling; it is then put into clean vessels for use in pharmacy, the arts, &c. FAT, likewise denotes an uncertain measure of capacity. Thus a fat of isinglass contains from 3% cwt. to 4 cwt. ; a fat of unbound books, four bales; of wire, from 20 to 25 cwt. ; and of yarn, from 220 to 221 bundles. FATA MORGANA, a singular aerial phenomenon, seen in the straits of Messina. When the rising sun shines from that point whence its incident ray forms an angle of about forty-five degrees on the sea of Reggio, and the bright surface of the water in the bay is not disturbed either by the wind or current, when the tide is at its height, and the waters pressed up by currents to a great elevation in the middle of the channel; the spectator being placed on an eminence with his back to the sun, and his face to the sea, the mountains of Messina rising like a wall behind it, and forming the back ground of the pic- ture; on a sudden there appears in the water, as in a catop- tric theatre, various multiplied objects; that is to say, num- berless series of pilastres, arches, castles, well delineated regular columns, lofty towers, superb palaces, with balconies and windows, extended alleys of trees, delightful plains, with herds and flocks, armies of men on foot, on horseback, and many other strange images, in their natural colours, and pro- per actions, passing rapidly in succession along the surface of the sea, during the whole of the short period of time while the above-mentioned causes remain. All these objects, which are exhibited in the Fata Morgana, are proved by the accurate observations of the coast and town of Reggio, by P. Minasi, to be derived from objects on shore. If, in addition to the cir- cumstances we before described, the atmosphere be highly im- pregnated with vapour, and dense exhalations, not previously dispersed by the action of the wind and waves, or rarefied by the sun, it then happens, that in this vapour, as in a curtain extended along the channel to the height of above forty palms, and nearly down to the sea, the observer will behold the scene of the same objects not only reflected from the surface of the sea, but likewise in the air, though not so distinctly or well defined as the former objects from the sea. Lastly, if the air be slightly hazy and opaque, and at the same time dewy and adapted to form the iris, then the above-mentioned objects will appear only at the surface of the sea, as in the first case, but all vividly coloured or fringed with red, green, blue, and other prismatic colours. As the day advances, the fairy scene gradually disappears. But the most singular instance of atmospherical refraction we ever heard of, was that described in the Philosophical Transactions, as having taken place at Hastings. The coast of Picardy, which is between forty and fifty miles distant from that of Sussex, appeared suddenly close to the English shore. The sailors and fishermen crowded down to the beach, scarcely believing their own eyes; but at length they began to recognize several of the French cliffs, and pointed out places they had been accustomed to visit. From the summit of the eastern cliff or hill, a most beautiful scene presented itself, for at one glance the spectators could see Dungeness, Dover cliffs, and the French coast, all along from Calais to St. Valleroy; and, as some affirmed, as far to the westward even as Dieppe. By the telescope, the French fish- ing boats were plainly seen at anchor; and the different colours of the land on the heights, with the buildings, were perfectly discernible. This refractive power of the atmosphere was probably produced by a diminution of the density of its lower stratum, in consequence of the increase of heat commu- nicated to it by the rays of the sun, powerfully reflected from the surface of the earth. The delusion. in the desert, between Alexandria and Cairo, mentioned by M. Monge, which repre- sented villages surrounded by water, when they were, in fact, in the midst of burning sands, is attributed to the same cause. FATHOM, a measure of six feet, used to regulate the length of the cables, rigging, &c. and to divide the lead (or sounding) lines, &c. F. E. E. F E L 303. DICTIONARY of MECHANICAL scIENCE. FEALTY, in Law, an oath taken on the admittance of a tenant to be true to the lord of whom he holds his land; but it chiefly appertains to copyhold estates held in fee and for life; and the fealty of a subject to his prince. FEATHER, in Physiology, a general name for the covering of birds. Feathers make a considerable article of commerce, particularly those of the ostrich, heron, swan, peacock, goose, &c., for plumes, ornaments, beds, pens, &c. , Geese are plucked in some parts of Great Britain five times in the year, and in cold seasons many of them die by this barbarous custom. Those feathers that are brought from Somersetshire, are esteemed the best, and those from Ireland the worst. best method of curing feathers is to lay them in a room, exposed to the sun; and when dried, to put them in bags, and beat them well with poles to get off the dirt. Feathers, when chemically analyzed, seem to possess nearly the same properties with hair. The quill is composed chiefly of coagu- lated albumen, without any traces of gelatine. - FEATHER-MILL, in the salt-works, the partition in the middle of the furnace, which it divides into two chambers. FEBRUARY is derived from Februa, an old Latin word, for from the very foundation of the city, we meet with Februa for purification; and Februare, to purge or purify. In this month the Romans held a feast in behalf of the manes of the deceased; and Macrobius tells us, that in this month also sacrifices were performed, and the last offices were paid to the defunct. The Housekeeper's Kalendar for this month presents in season, Fish: cod, soles, sturgeons, plaice, flounders, skate, turbot, thornback, whitings, smelts, lobsters, crabs, oysters, prawns, tench, carp, perch, eels, lampreys, and crawfish.-Meat: Beef, mutton, veal, lamb, and pork.-Poultry : Turkeys, capons, pullets, fowls, chickens, pigeons, pheasants, partridges, wood- cocks, snipes, hares, and rabbits.-Vegetables: Cabbages, Savoys, coleworts, sprouts, broccoli, cardoons, beets, parsley, chervil, endive, sorrel, celery, chardbeets, lettuces, cresses, mustard, rape, radishes, turnips, tarragons, mint, burnet, tansy, thyme, savory, marjoram, radishes, cucumbers, asparagus, kidney beans, carrots, turnips, parsnips, potatoes, onions, leeks, sha- lots, garlic, rocambole, salsafie, skirret, scorzonera, and arti- chokes.—Fruit: Pears, apples, grapes, &c. In the kingdoms of nature during this month, we find that bees begin to come out of their hives, sheep drop their lambs, gcese begin to lay, rooks, partridges, &c. begin to pair, build their nests, and lay. - - In the Kitchen Garden now sow radishes, spinage, lettuce, pease and beans, early Dutch turnips and onions for a full crop. Propagate by offsets, mint, balm, sorrel, tansy, fennel, and tar- ragon. Transplant onions, carrots, turnips, beet, celery, and endive. Dig and trench in moderate weather, and perform all operations only in dry weather. * In the hardy Fruit Department, plant all sorts of fruit-trees when the weather is fine, and strawberries. Protect roots of new-planted trees, and tops of nectarine, peach, plum, and apricot trees coming into blossom. Prune these ; also fruit vines, gooseberries, currants, and raspberries. Examine your fruit room, and remove all tainted fruit. - In the culinary Hot-house Department, cucumbers, melons, salads, and potatoes, are forced—as are also kidney and French beans, and cauliflowers; the heat of all hotbeds is to be kept up by linings. Attend to the proper temperature of the pinery; and commence forcing peaches, cherries, and vines. In the open ground Flower Garden, sow a few hardy annuals, mignonette, and ten-weeks stock. Propagate hardy plants from the root and herb. September and March are the best seasons for this work. Prepare plants, &c. In the Hot-house Flower Garden Department, force bulbs, pre- pare for annuals, border flowers, and Dutch roots, and give air whenever the thermometer rises to 70°. - In the Pleasure Ground and Nursery Departments, plant deci- duous trees and shrubs; prune, dig, sweep and roll gravel walks; lay quince, walnut, and mulberry trees. Plant orna- mental shrubs and forest trees; and fell timber. - FEE, in Law, a complete feudal property; which, if absolute, is called a fee-simple; but if limited, a fee-tail. A tenant in fee- The vacant ground for trees and simple, is he that hath lands, tenements, or hereditaments, to hold to him and his heirs for ever, generally, absolutely, or simply ; without mentioning what heirs, but referring that to his own pleasure, or to the disposition of the law. This inheritance of lands may be carved out into divers estates: as, if one grants a lease for 21 years, or for one or two lives, the fee-simple remains vested in him and his heirs; and after the determination of those years or lives, the land reverts to the granter or his heirs, who shall hold it again in fee-simple. Limited fees are usually elogged with conditions or qualifi- cations of any sort. - FEE Qualified, is such a freehold estate as has a qualification subjoined to it, and must determine whenever the qualification is at an end. FEE Farm, is when the lord, upon the creation of the te- nantcy, reserves to himself either the rent for which it was before let, or a fourth part of that farm rent. - FEELERS, in Natural History, a name used by some the horns of insects. - - - FEELING, one of the five external senses; the object o which is every body that has consistency or solidity enough to move the surface of our skin. It is necessary to perfect feel- ing, that the nerves should form small eminences, because they are more easily moved by the impression of bodies than an uniform surface. By means of this structure, we are enabled to distinguish not only the size and figure of bodies, their hardness and softness, but also their heat and cold. FELIS, Cat, in Zöology, a genus of the mammalia class, belonging to the order of ferae. 1. Felis leo, the lion, an inhabitant of Asia and the interior of Africa. 2. Felis tigris, tiger, is a native of the warmer parts of Asia, and the Indian islands. 3. Felis pardus, panther, principally found in Africa, and is to that country what the tiger is to Asia, with this alleviating circumstance, that it is supposed to prefer the destruction of other animals to that of man. Felis leopardus, the leopard, is a native of Senegal and Guinea, as well as of many other parts of Africa; it also occurs in several parts of Asia. In its manners it resembles the panther. 5. Felis jubata, the hunting leopard, a native of India, where it is said to be tamed, and used for the chase of antelopes and other animals. If it misses its prey, it returns at the call of its master. 6. Felis uncia, the ounce, scarcely inferior in size to the leopard, is a native of several parts of Africa and Asia. 7. Felis onca, the Brazilian tiger, is a native of South America, and is a very fierce and destructive animal. 8. Felis pardalis, ocelot, is a ferocious animal, and inhabits the hotter parts of South America. 9. Felis puma. The puma is the largest of the American beasts of prey, and a native of many parts of America, from Canada to Brazil. 10. Felis discolor, the black tiger, is also a native of America, and is considered as a very destructive animal. 11. Felis tigrina, margay, a native of South America, is about the size of a cat. 12. Felis capensis, the Cape cat, inhabits the neighbourhood of the Cape of Good Hope, and in its manners resembles the common cat. 13. Felis manul. This species inhabits the middle part of northern Asia. It is of the size of a fox, and is of a strong and robust make. 14. Felis catus; the cat, in a state of wildness, and from which are supposed to have proceeded all the varieties of the domestic cat; it is a native of the north of Europe and Asia. The man- ners of the wild cat resemble those of the lynx, living in woods, and preying on young hares, birds, and a variety of other ani- mals, which it seizes by surprise. No animal exhibits a greater degree of maternal tenderness than the cat. She even possesses a propensity to nurse with tenderness the young of a different individual. The fur of the cat yields electric sparks when rubbed: and if a clean and dry domestic cat is placed, in frosty weather, on a stool with glass feet, or insulated by any other means, and rubbed for a certain space in contact with the wire of a coated phial, it will be effectually charged by this method. 15. Felis serval. This is a native of India and Tibet, and is a very rapacious animal. 16. Felis chaus, is an inha- bitant of the western side of the Caspian sea, and the Persian provinces of Ghilan and Masenderan. 17. Felis rufa, bay lynx. This species is about twice the size of a large cat, and is a native of North America. 18. Felis caracal, or Persian for * * lynx, is a native of Asia and Africa; it is used not only in the 304. F E L F E. N. DICTIONARY OF MECHANICAL SCIENCE. chase of the smaller quadrupeds, but of the larger kinds of birds, such as herons, cranes, pelicans, &c. 19. Felis lynx, the common lynx, is found in all the colder regions of Europe, Asia, and America, residing in thick woods, and preying on hares, deer, birds, and other animals. o FELLING of Timber. Its proper season is determined by various causes, as maturity of growth, defects in the trees, and new arrangements. Every tree that wears the picture of decay, ought to be felled, let the price and demand be what they may. But when the demand is brisk, and the price high, such as are near perfection may be cut down. In all trees there are three stages, youth, manhood, and age. The begin- ning of manhood is the fittest period for removing trees. , All plantations, when arrived at maturity, ought to be cut down. and replanted. Winter is the proper season for felling trees not to be disbarked; but summer for the resinous tribes. In spring and autumn, the wood is fullest of sap ; in winter and summer least so, and is the time fittest for being levelled with the earth. FELLOES, six pieces of wood, which, with the addition of a nave and twelve spokes, make the wheel of a gun-carriage. FELLOWSHIP, the name of a rule in Arithmetic, useful in balancing accounts between traders, merchants, &c.; as also in the division of common land, prize-money, and other cases of a similar kind. Fellowship is of two kinds, single and double; or fellowship without time, and fellowship with time. Single FEllowship, is when all the monies have been em- ployed for the same time, and therefore the shares are directly as the stock of each partner. The rule in this case is as fol- łows: As the whole stook : the whole gain or loss :: each man’s particular stock : his particular share of the gain or loss. Example. A bankrupt is indebted to A £1000, to B £2000, to C £3000; whereas his whole effects sold but for £1200: re- quired each man's share. Here the whole debt is £6000, therefore - 1000 : £200, A’s share, As 6000 : 1200 : : }; : £400, B's share. C3000 : £600, C's share. Double FellowsHIP, is when equal or different stocks are employed for different periods of time. The rule in this case is as follows: Multiply each person's stock by the time it has been engaged; then say, As the sum of the products : the whole gain or loss :: each particular product : the corre- sponding share of the gain or loss.-Frample. A had in trade #. for four months, and B £60 for five months; with which they gained £24; required each person's particular share. 50 × 4 = 200 60 × 5 = 300 ... on . . $ 200 : £ 9. 12s. A's gain. • - 500 : 24 : : } 300 : £14. 8s. B’s gain. See Bonnycastle’s “Arithmetic,” and most other authors on this subject. * FELONY, in Law, means every species of crime which occasions at common law the forfeiture of lands or goods; as wilful murder, forgery, house-breaking, house-burning, horse and sheep-stealing, rape, highway-robbery, cutting and maim- ing, piracy, coining, and treason against the king, are punish- able with death. Numerous other offences are also punishable with death; but the sentence is generally commuted into trans- portation for life: smaller offences involve transportation for fourteen or seven years; and petty ones are punished by im- prisonment, whipping, pillory, burning in the hand, or by fines. The idea of felony is, indeed, so generally connected with that of capital punishment, that we find it difficult to separate them; and to this usage the interpretations of the law do now con- form. And, therefore, if a statute makes any new offence felony, the law implies that it shall be punished with death, by hang- ing, as well as with forfeiture; unless the offender prays the benefit of clergy, which all felons are entitled once to have, unless the same is expressly taken away by statute. And the benefit of clergy means a privilege formerly allowed, by virtue of which a man convicted of felony, or manslaughter, was put English), and if the Ordinary of Newgate said Legit ut Clericus, i. e. “He reads like a clerk”—or parson—the felon was only passes into porcelain clay. burned in the hand, and set free, otherwise he suffered death for his crime. - . . . . FELSPAR, is a hard kind of stone which varies much in colour, being flesh red, bluish gray, yellowish white, milk white, or brownish yellow. It is found in mass, disseminated or crystallized in four, six, and ten-sided prisms; will strike fire with steel, and is sometimes opaque and coloured, some- times transparent and whitish. The name is derived from the German language, and signifies spar of the fields. It is a very common substance, and constitutes a principal part of many of the highest mountains of the world. When exposed to wea- ther, it gradually acquires an earthy appearance, and at length Felspar is of great use in the manufacture of the finer earthenwares. Of the two substances which chiefly compose the porcelain of China, one called petunzé, is a whitish laminar kind of felspar, and the other; called kaolin, very nearly resembles the common species in its decomposed State. This mineral is used in the celebrated porcelain manufactured at Seves, near Paris, for the purpose of giving to it a white and transparent appearance. Previously to being used, it is pulverized, made into a paste, and suffered to dry. It is sometimes applied to the surface of ornamental vases in the form of enamel. . Labrador FELSPAR, is a very beautiful stone of smoky gray colour, intermingled with veins and shades of blue, green, and golden yellow, exhibiting a brilliant play of colours, according to the position with respect to the light in which the stone is held. The original discovery of this singular mineral was by the Moravian missionaries, on the island of St. Paul, near the coast of Labrador; but it has since been found in various parts of Norway and Siberia. In the late Leverian museum there was exhibited a remarkably fine mass of Labrador fel- spar, the surface of which was polished, and exhibited some of the most splendid and beautiful colours that could be imagined. It was considered to have been the most capital specimen that was ever brought to England. This mineral, on account of its hardness, its brilliancy, and its capability of receiving a high polish, is in considerable estimation among lapidaries for different kinds of ornamental work, particularly for the tops and bottoms of snuff-boxes, for brooches, and necklaces. § FELTING, the method of working up hair or wool into a species of cloth, independently of either spinning or weaving. See HAT-MAKING. - FELUCCA, a little vessel with oars, frequent in the Medi- | terranean. - - FEMINEUS, Flos, a female flower. By this name Linnaeus denominates a flower which is furnished with the pistillum. Female flowers may be produced apart from the male, either on the same root, or on distinct plants. The birch and mul- berry are examples of the first case; willow and poplar of the second. FEMME Covert, in Law, a married woman; as femme sole is an unmarried woman, whose debts contracted before mar- riage, become those of her husband after it. FEN, a place overflowed with water, or abounding with bogs, as the bogs in Ireland, the fens in Lincolnshire, Kent, and Cambridgeshire. These fens abóund in duck, teal, mallards, pike, eels, &c.; and a herbage that is very nourishing to sheep and cattle. - FENCE, in Gardening and Husbandry, a hedge, wall, or ditch, &c., or other enclosure made round gardens, fields, woods, &c. Fences round parks are generally'of paling, which, if well made of winter-falken oak, will last 40 years. But a principal thing to be observed, is, not to have such fences too heavy, as their own weight will cause them to decay. The posts should not be more than 9 feet asunder, the rails tri- angular, the pales cleft, # inch one edge and + the other; and every alternate pale 9 inches above the intermediate one. FENCING, an accomplishment both agreeable and useful— agreeable, as it is a noble and innocent amusement; useful, as it forms the body, and furnishes its practitioners with a most e º º | manly method of self-defence, whether in support of their to read in a Latin Book, of a Gothie black character (or old honour, or to protect life, when attacked by those turbulent and dangerous bullies, whose chastisement is of service to | society in general. F E. R. F E S 305 DICTIONARY OF MECHANICAL scIENCE. " FEODAL, Feud, or Fee System, called also “the Feudal System,” which existed in Europe, in time back, was this:— When the northern nations, the Goths, Vandals, &c. overran the Roman empire in the 5th century of our aera, they brought the feudal system along with them, and established it wher- ever they settled. According to this system, the victorious general allotted considerable tracts of land to his principal officers; while they, in like manner, divided their possessions among the inferior officers, and such of the common soldiers as were bravest in battle. This stipend of land they called a fief, feod, or feud ; and the condition of tenure was, that the tenants in fief should serve the owner of the fee-simple, or lessor, or lord, at home and abroad in all wars and military expeditions. To this they bound themselves by an oath of fealty, so that a reciprocal tie linked the highest chief with the humblest of his followers, who could not only enjoy but dispose of their terri- tory as they pleased, the possessor being, by his occupancy, bound for military service, as was his predecessor. When William the Conqueror was crowned king of England, he secured his victory by loading the Saxons with the heaviest chains of the feudal laws, and imposed upon all the proprietors of land, various hardships unknown before in England. These were the subjects of complaint and opposition for many ages after the conquest. With the Norman language, which was adopted in the courts of justice, were introduced the Norman laws. . The ancient trial by jury was superseded by the uncer- tain and unjust decision by single combat, a practice which was established by law, and conducted with regular ceremonies and forms of devotion. The extinction of all fires at the melancholy sound of the curfew or evening bell, was a striking emblem of the extinction of liberty. The nation groaned under every distress that a politic and obdurate conqueror could inflict'; and their chains were so firmly riveted, as to frequire a degree of energy and unanimity to break them, which the oppressed Saxons had not sufficient resolution to exert. The Conqueror not only broke the line of hereditary succession to the crown of England, but reduced the people to the most abject slavery. The confiscation of the estates of the Saxon nobles indicated both his policy and rapacity. He caused a survey to be made of all the lands in the kingdom, with a distinct account of their extent and value, and the names of the proprietors. This curious record, called Doomsday Book, Domus Dei Liber, is preserved in the Exchequer, and has been printed. These lands were divided into 60,215 military fiefs; some were reserved by the Conqueror for himself; and the rest were bestowed upon his Norman followers, to be held under the obligation of each vassal taking up arms, and appearing in the field, whenever the king raised his standard of war. FEOFFMENT, in Law, the gift of any corporeal heredita- ment to another. He that so gives or enfeoffs, is called the feoffor, and the person enfeoffed, or put in possession, is deno minated the feoffee. . FERAE, in Zöology, an order of quadrupeds, the distinguish- ing characters of which are, that all the animals belonging to it have fore-teeth conic, usually six in each jaw; tusks longer; grinders with conical protections; feet with claws; claws subulate ; food carcasses, and preying on other animals. FeRE Natura, are animals of a wild nature, in which a man has only a qualified and limited property, which some- times subsists, and at other times does not. FER DE FOURCHETTE, in Heraldry, a cross having at each end a forked iron, like that formerly used by soldiers to rest their muskets on. And Fer de Moulin, is a bearing sup- posed to represent the iron ink, or ink of a mill, which sustains the moving millstone. FERGUSON, JAMEs, an eminent experimental philosopher and mechanic, was born of very poor parents, in Bamffshire, in Scotland, in 1710; in which humble situation he very early gave great proofs of an original and enterprising genius, which he afterwards displayed much to his own credit and emolu- ment; having accumulated at his death, which happened in 1776, a sum of £6000. Mr. Ferguson was fellow of the Royal Society, and author of some works on astronomy and me- chanics. - - FERMAT, Peter, a celebrated French mathematician, was born in 1590, and became, by his talents and acquirements, bles, according to their abundance. counsellor of the parliament of Toulouse. Fermat was inti- mately acquainted with all the first-rate mathematicians of his age, either personally or by correspondence. . . . . FERMENTATION, an intestine motion, excited by the assistance of proper heat and fluidity between the integrant and constituent parts of farinaceous, saccharine, and a few other substances, from which new combinations of their re- spective principles result. The various kinds of fermentation Fº The Vinous; 2. The Acetous; 3. The Panary; 4. The utrid. +. - - - 1. The Vimous Fermentation.—When a solution of saccharine matter, or saccharine matter and starch, or sweet juices of fruits, suffer this change, the result is beer or wine, and the process is called a vinous fermentation. - - 2. Acetous Fermentation.—When wine, or any fermented or vinous liquor, is exposed to a heat, from 75° to 80° Fahrenheit, and access of air is permitted, the fluid becomes torpid, a new change of principles takes place; it loses its taste and smell, becomes sour, and is converted into vinegar. - - 3. Panary Fermentation.—This is the fermentation produced § the action of yeast or flour and water in the making of read. - * * - 4. Putrid Fermentation.—This is the last change or final decomposition of vegetables. Without moisture, heat, and a due access of air, this decomposition does not take place. In this state of fermentation, ammonia is thrown out, accom- panied by a very offensive smell. Vegetables which contain albuminous matter and gluten, are most liable to putrefaction or fermentation. - : FERRAGO, simply rust, called in Chemistry oacide of iron; from ferrum, iron. FERRETTO, in Glass Making, a substance used in colour- ing glass, and obtained from a simple calcination of copper and powdered brimstone, or copper and white vitriol. See GLAss MAKING. FERRUGINOUS, any thing partaking of iron, or that con- tains particles of that metal. FERRY, a liberty by prescription, or by the king’s grant, to have a boat for passage on a frith or river, for carrying passen- gers, horses, or any goods, over the same for a reasonable toll Or tax. • . FERTILITY, as of soils, &c. denominates their being fruit- ful, prolific, &c. In all animals, every thing that promotes health conduces to fertility; and perfect fecundity must result from good blood, good spirits, high health, and perfect animal functions. All the medicines, nostrums, and specifics, different from these, are arrant quackery. Such is the doctrine of phy- siologists; yet we see most fertile the wives of the labouring poor—of mechanics, who earn perhaps only 18 shillings a week, on which a family of seven persons has to be supported. This is incontrovertible. It is obvious then, that high living is not necessary to the fecundity of our species, though it is also a fact that there are living, at this time (1825), mothers of ten, nay, sixteen children, who have all their lives lived in the lap of luxury. As respects the fertility of the mother earth, soils may be improved by pulverization, which allows the rain to penetrate the soil, and gives scope to the roots of vegeta- It besides increases the capillary attraction, which is always greater in proportion as the particles of earth are finely divided. Air, light, and heat, are also communicated to under strata, by turning up and lay- ing open the soil; and plants and vegetables cannot flourish in all their perfection without those great elements of animating nature. Ploughing, digging, harrowing, raking, dunging, scat- tering of ashes, and alkali residues, are the great agents in mixing, enriching, warming, and nourishing soils, so as to give them all that fertility of which they are capable; and where these important matters are well regulated, fertility will ordi- marily take place, and the desire of the owners or occupiers of the land will ensue. FESSE, in Heraldry, one of the nine honourable ordinaries. Fesse point is the exact centre of the escutcheon; fesse ways denotes any thing borne after the manner of a fesse, i.e. in a rank across the middle of the shield; and fesse per fesse implies a parting across the middle of the shield from side to side, through the fesse point. * t - 4 I 306 F I F F I L DICTIOANRY OF MECHANICAL SCIENCE. FESTOON, in Architecture, . &c. an ornament in form of a £ garland of flowers, fruits, and leaves, intermixed or twisted $º together, and generally more & bulky in the middle than to- º wards the ends, which hang down perpendicularly, as in the annexed figure. . . . . . . . . * . FEU DUTY, in Scots Law, the annual duty which a vassal, by the tenor of his right, becomes bound to pay his superior; hence the tenure of few holding. FEVER, a disease in which the body is violently heated, the pulse quickened, and the patient attacked alternately with heat and cold. Fevers are either intermittent, continued, remittent, scarlet, &c. and usually attended with headache, thirst, gid- diness, and sometimes difficulty of breathing. Their treatment is as various as their names, and the systems of practitioners. But we cannot enter upon this topic, which is of too much consequence to be handled in a few pages. ... FIBRE, in Anatomy, a simple body, being fine and slender like a thread, and serving to form other parts. Hence fibrin is that substance which constitutes the fibrous part of the mus- cles of animals. FIBRIN, is a peculiar organic compound found in vege- tables and in animals. There are few vegetables from which this substance is obtained distinctly characterized, but it is found abundantly in all animals. Chyle, the blood, and the muscular flesh, produce it. If the blood from the veins be beaten with rods, long reddish filaments of fibrin will adhere to them, and if washed in cold water, they will become colour- less, and the matter of fibrin will be found to be solid, white, insipid, without colour and smell. When moist, it is, in some degree, elastic; when dried, it is yellow, hard, and brittle. By distillation it yields carbonate of ammonia, some acetate, brown oil, and gaseous products. phosphate of magnesia, with carbonate of lime and soda. FIBROLETE, a mineral, first observed by Bournon, in the matrix of the imperfect corundum. It is composed of 58.25 alumina, 38.00 silica, 3.75 a trace of iron, and loss. - FICUS, a genus of the trioecia order, in the polygamia class of plants, and in the natural method ranking under the 53d order, scabridae. There are 56 species, of which the banian- tree is the most remarkable. See BANIAN-TREE. FIDD, on board ship, is an iron or wooden pin, to splice and fasten ropes together. - FIELD, in Heraldry, the whole surface of the shield, or the continent, so called because it containeth those achievements anciently acquired in the field of battle. on which the colours, bearings, metals, furs, charges, &c. are represented. , - FIELD Book, in Surveying, the angles, stations, distances, &c. are set down. See SURVe YING of Land. - - FIELD Pieces, small cannons from 3 to 12 pounders, carried along with an army; and the Field Staff, carried by the gun- ners, is about the length of a halbert, with a spear at one end, having on each side ears screwed on, like the cock of a match- lock, into which the bomadiers screw lighted matches when they are upon command; and then the field staffs are said to be armed. - FIELD. Works, in Fortification, are those thrown up by an army in besieging a fortress, or by the besieged to defend the place; as the fortifications of camps, highways, &c. FIERI FACIAS, a judicial writ that lies at all times within the year and day for him who has recovered in an action of debt or damages, to the sheriff, to command him to levy the debt or damages of his goods against whom the recovery was had. - * - - - FIFE, a wind instrument of the martial kind, consisting of a short narrow tube with holes disposed along the side, for the regulation of its tones. . FIFTH, in Music, a distance comprising four diatonic inter- vals, i. e. three tones and a half. Fifth Sharp, is an interval consisting of eight semitones. t FIFTEENTH, an ancient tribute or tax laid upon cities, There remains in the retort a charcoal, which, after combustion, leaves phosphate of lime, It is now the ground boroughs, &c., through all England, and so termed, because it amounted to a fifteenth part of what each city or town had been valued at; or it was a fifteenth of every man’s personal estate, according to a reasonable valuation. In doomsday-book, there are certain rates mentioned for levying this tribute yearly; but since, any such tax cannot be levied but by parliament. FIGURE, in Grammar, is a deviation from the natural rules of etymology, syntax, and prosody, either for brevity, ele- gance, or harmony. FIGURE, in Rhetoric, is a manner of speaking different from the ordinary and plain mode, and more emphatical, expressing a passion, or containing a beauty. FIGURE of a Body, in Geometry and Mensuration, denotes generally its form or shape; whence as all bodies are of some form or figure, figurability is reckoned amongst the essential properties of body or matter. A body without figure would be without limits, and must therefore be infinite. - Figure, in Painting and Designing, denotes the lines and colours which form the representation of any animal, but more particularly of a human person. See DRAWING. - - Figures, in Arithmetic, are the mine digits, 1, 2, 3, 4, &c. FILACER, or FILAzer, an officer of the court of common pleas, so called, because he files those writs whereupon he makes out process. There are fourteen of them in their several divisions and counties, and they make out all writs, and pro- cesses upon original writs, issuing out of chancery. FILAMENT, in Amatomy and Natural History, &c. is the same as fibre, and is applied to those fine threads that compose the flesh, nerves, skin, plants, roots, &c. of all vegetating organized bodies. Hence the thread, cloth, &c. from flax, nettles, hop stalks, &c. - FILAM ents, Vegetable, form a substance of great use in the arts and manufactures; furnishing thread, cloth, cordage, &c., as the filamentous parts of hemp and flax are employed among us. . - FILARIA, a genus of insects of the order intestina. There are several species, infesting different animals and insects. The medinensis is the most remarkable species; it inhabits the Indies, and is frequent in the morning dew, whence it enters the feet of the slaves, and creates the most troublesome itch- ings, accompanied with inflammation and fever. - FILE, among Mechanics, a furrowed tool used to polish or prepare metals, &c. and usually cut in steel. - Mr. Nicholson has obtained a patent for machinery for the manufacture of files; which consists, 1. Of a carriage, in which the file is fixed, and moved for the purpose of receiving the strokes of a cutter or chisel. 2. The anvil by which the file is supported beneath the part which receives the stroke. 3. The regulating gear, by which the distance between the strokes is governed : and 4. The apparatus for giving the stroke or cut. Those four parts are supported by a frame of wood or metal, according to the nature of the work to be performed. By this machinery, a blind man can cut a file with more exactness than the most skilful workman in the ordinary Way. FILES, MACHINEs for Cutti NG OF. There have been various contrivances for this purpose, but among the best we are acquainted with, is one described in the Transactions of the American Philosophical Society. A AAA, (as in the following figure,) is a bench made of well-seasoned oak, the face of which º - ETSU Wº: ſº-- * T Ét º sº º E E. B}: º i. - Sº l Rºſº TAs -Es-RE AYS is planed very smooth. ... B B B B B, the feet of the bench, which should be substantial. C C C C, the carriage on which the files are laid, which moves along the face of the bench AAAA, parallel to its sides, and carries the files gradually under the edge of the cutter or chisel H. H., while the teeth are cut; this carriage is made to move by a contrivance somewhat F I L F-I-R, DICTIONARY OF MECHANICAL SCIENCE. similar to that which carries the log against the saw of a saw- mill, as will be more particularly described. D D D, are three iron rods inserted in the ends of the carriage C C C C, and | - divers places, but generally as a sort of corona over a greater moulding. In-Heraldry, a bordure or orle, one-third part the : breadth of the common bordure. passing through holes in the studs EEE, which are screwed firmly against the ends of the bench A.A.A.A, for directing the course of the carriage C C C C, parallel to the sides of the said bench. FF, two upright pillars, mortised firmly into the bench AAA A, nearly equidistant from each end of it, near the edge, and directly opposite to each other. G, the lever or arm which carries the cutter H. H., (fixed by the screw I,) and works on the centres of two screws KK, which are fixed into the two pillars FF, in a direction right across the bench A A A. A. By tightening or loosening these screws, the arm which carries the chisel may be made to work more or less steadily, L is the regulating screw, by means of which the files may be made coarser or finer; this screw works in a stud, M, which is screwed firmly upon the top of the stud F : the lower end of the screw L bears against the upper part of the arm C, and limits the height to which it can rise. spring, one end of which is screwed to the other pillar F, and the other end presses against the pillar O, which is fixed upon the arm.G.; by its pressure it forces the said arm upwards, until it meets with the regulating screw, L. P is an arm joint into the end of the stud or pillar O ; and by the motion of the arm G, is made to move the ratch-wheel Q. This ratch- head or pinion R, on the opposite end; this takes into a piece SS, which is indented with teeth, and screwed firmly against one side of the carriage C C C C : by means of this piece motion is communicated to the carriage. T is a clamp.for fastening one end of the file Z Z, in the place or bed on which it is to be cut. which works by a joint W, firmly fixed into the carriage C C C C, Y is a bridge, likewise screwed into the carriage, through which the screw X passes, and presses with its lower end against the upper side of the clamp V ; under which clamp the other end of the file Z Z, is placed, and held firmly in its situation while it is cutting, by the pressure of the said clamp V. formed in the body of the carriage, something broader and lead is formed variously, so as to fit the different kind of files which may be required. At the figures 22, are two catches which take into the teeth of the ratch-wheel Q, to prevent a recoil of its motion. 33 is a bridge to support one end 4, of the axis of the ratch-wheel Q. 5, a stud to support the other end of the axis of that wheel. When the file or files are laid in their place, the machine must be regulated to cut them of the due degree of fineness, by means of the regulating screw L; which, by screwing further through the arm M, will make the files finer, and vice versa, by unscrewing it a little, will make them coarser; for the arm G. will by that means have liberty to rise the higher, which will occasion the arm P, with the claw, to move further along the periphery of the ratch-wheel, and consequently communicate a more extensive motion to the carriage C C C C, and make the files coarser. with a hammer on the head of the cutter or chisel H H, all the movements are set to work, and by repeating the stroke with the hammer, the files on one side will eventually be cut. They must then be turned, and the operation repeated for cutting the other side. This machine may be made to work by water as well as by hand, to cut large or small, coarse or fine; or indeed any number at the same time. The materials and dimensions of this machine must be left to the judgment of the mechanic, but the whole must be capable of bearing a considerable portion of violence and thumping. . FILLAGREE WoRK, a kind of enrichment on gold or silver, wrought delicately like threads or grains, or both intermixed. The gold and silver fillagree of Sumatra is the most esteemed of the world, yet is it made with the coarsest tools, a piece of bamboo cane serving as a blow-pipe, a couple of old nails as a pair of compasses: an old iron hoop serves many purposes. The price of the workmanship depends on the difficulty or un- commonness of the pattern, but, in general, it is only one-third N is a steel || ture of nations. produce of the various taxes, the aggregate amount of which, after deducting the expenses of collecting, together with a few small articles which cannot properly be called taxes, forms the whole of the public income. - - V is another clamp or dog, at the opposite end, When the machine is thus adjusted, by striking | of the value of the metal, except in matters of fancy, when it amounts to as much as the gold. - - - - FILLET, in Architecture, a little square member used in It runs quite round, near the edge, as a lace over a cloak. It sometimes appears like a scarf across the shield. - FILLETs, in the Manege, the loins of a horse which begin at the place where the hinder part of the saddle rests. FILTER, or FILTRE, in Chemistry, a strainer through which any fluid is passed, to separate the gross particles, and render it limpid. * FILTERING BAsons, &c., are either natural or artificial, for the purpose of purifying water. Natural filters are found. in rocks, mountains, beds of sand, gravel, &c. Artificial filter- ing basons consist of equal parts of pipe-clay and coarse sand. They should be three-quarters of an inch thick. FILTRATION, in Chemistry, is sifting through the pores of paper, flannel, or fine linen or sand, pounded glass, or porous stones, and the like ; but it is used only for separating fluids from solids, or particles that may happen to be suspended in them, and not chemically combined with the fluids. with a claw at one end marked 6, the other end is fixed by a | FIN, in Natural History, a well known part of fishes, con- sisting of a membrane supported by rays, or little bony or car- - : tilaginous ossicles. - wheel is fixed upon an axis, which carries a small trundle- | FINANCE, the economy of the public revenue and expendi- The English system of finance rests on the FINE, in Law, has different significations. It sometimes denotes a formal conveyance of lands or tenements, or of any inheritable thing, in order to cut off all controversies: some- times it means a sum of money paid for entering into the pos- ! session of lands or tenements let by lease. a pecuniary mulct for an offence conducted against the king, or ! the lord of the manor. - - 7777 is a bed of lead, which is let into a cavity | Again, it signifies FINERS of gold and silver, are those who separate these metals from coarser ores. longer than the largest fixed files; the upper face of this bed of | FIRE, that invisible fluid by which bodies are expanded, and become hot, is best known from its effects; and to these, and not to the disputes that have agitated philosophers con- cerning this subject, must we look for all the knowledge to be gained respecting this chief agent in nature, on which animal and vegetable existence have so close and inscrutable a depen- dence, and without which it does not appear that nature could exist a single moment. Whenever you perceive a number of qualities always existing together, you are warranted to con- clude, that there is some substance which produces those qualities. - it has a constant tendency to diffuse itself uniformly, so as to Fire drives out other bodies from any given space; maintain an equilibrium; it dilates’some substances; it must have penetrated them; it expels other bodies, and takes their place; therefore we conclude, it must itself be a body—a real and material substance. Air is a substance, and not a quality. People who are unac- quainted with the principles of natural philosophy, would not suppose that the air by which we are surrounded is a material substance, like water, or any other visible matter. Being perfectly invisible, and affording no resistance to the touch, it must seem to them extraordinary to consider it as a solid and material substance; and yet a few simple experiments will convince any one that it is really matter, and possesses weight, and the power of resisting other bodies that press against it. And it differs from all other fluids in the four following particu- lars:— - 1. It can be compressed into a much less space than what it naturally possesses. 2. It cannot be congealed, or fixed, as any other fluids may. 3. It is of a different density in every part upward from the earth's surface, decreasing in its 'weight, bulk for bulk, the higher it rises. 4. It is of an elastic, or springy nature, and the force of its spring is equal. to its weight. Fire, in common with air, is subject to these laws. Light is $308 F I R. F I R. DICTIONARY OF MECHANICAL scIENCE. an emanation of fire; the decomposition of the rays of light - proves its materiality; what is light on the surface of a burn- ing glass, is fire at its focus; whatever, therefore, proves the materiality of light, is applicable to fire. We conclude, therefore, that fire is a real and material sub- stance; and by the word fire we mean that very subtile fluid which all men call fire; heat is an effect of fire, or a proof of its presence ; absolute heat and fire are words of the same import; relative heat is an epithet applied to the measured effects of fire. Fire penetrates all bodies, even the hardest; and one of its most constant characters is a continual ten- dency to equilibrium, or to flow from a warmer to a colder substance. - - Heat, considered as a sensation, or, in other words, sensible heat, is only the effect produced upon our organs by the motion of caloric, disengaged from the surrounding bodies. In gene- ral we receive impressions only in consequence of motion, and it might be established as an axiom, that without motion there is mo sensation. This general principle applies very accurately to the sensations of heat and cold. When we touch a cold body, the caloric, which always tends to become in equilibrio in all bodies, passes from our hand into the body we touch, which gives us the feeling or sensation of cold. The contrary happens when we touch a warm body; the caloric then, in passing from the body into our hand, produces the sensation of heat. If the hand and the body touched, be of the same temperature, or very nearly so, we receive no impression either of heat or cold, because there is no motion or passage of caloric. See CALoRic, Evaporation, Heat, PY Rometer. FIRE Arrow, a steel or iron dart used by privateers and pirates, to set fire to the sails of the enemy in battle. FIRE, Balls of, in Meteorology, a kind of luminous bodies, generally appearing at a great height above the earth, with a splendour surpassing that of the moon; and sometimes equal- ing her apparent size. They generally proceed in this hemi- sphere from north to south with vast velocity, frequently breaking into several smaller ones, sometimes vanishing with a report, sometimes not. FIRE Ball, in the art of War, a composition of meal-powder, sulphur, saltpetre, pitch, &c., about the bigness of a hand- grenade, coated over with flax, and primed with a slow composition of a fusee. This is to be thrown into the enemy’s works in the night-time, to discover where they are: or to fire houses, galleries, or blinds of the besiegers; but they are then armed with spikes, or hooks of iron, that they may not roll off, but stick or hang where they are designed to have any effect. FIRE Barrels, used in fire-ships, and ought to be of a cylin- drical form, as best adapted to contain the reeds with which they are filled, and more convenient for stowing them between the troughs in the fire-room. Their inside diameters should not be less than 21 inches, and 30 inches are sufficient for their length. The bottom parts are first well stowed with short double-dipped reeds placed upright, and the remaining vacancy is filled with fire-brand composition, well mixed and melted, and then poured over them. The composition used for this purpose is a mass of sulphur, pitch, tar, and tallow. There are five holes of 3-4 inch in diameter, and three inches deep, formed in the top of the composition while it is yet warm; one being in the centre, and the other four at equal distances round the sides of the barrel. When the composition is cold and hard, the barrel is primed by filling those holes with fuze composition, which is firmly driven into them so as to leave a little vacancy at the top to admit a strand of quick- match twice doubled. The centre hole contains two strands at their whole length, and every strand must be driven home with mealed powder. The loose ends of the quick-match being then laid within the barrel, the whole is covered with a dipped curtain, fastened on with a hoop that slips over the head of the barrel to which it is nailed. The barrels should be made very strong, not only to support the weight of the composition before firing, when they are moved or carried from place to place, but to keep them together whilst burning: for if the staves are too light and thin, so as to burn very soon, the remaining compo- sition will tumble out and be dissipated, and the intention of the barrels to carry the flame aloft, will accordingly be frus- trated. The curtain is a piece of canvass, nearly a yard in breadth and length, thickened with melted composition, and covered with saw-dust on both sides. - FIRE in Chimneys, method of Ectinguishing. It is well known, that the inner parts of chimneys easily take flre; the soot that kindles therein, emits a greater flame, according as the funnel is more elevated, because the current of air feeds the fire. If this current could therefore be suppressed, the fire would soon be extinguished. The surest and readiest method is, to apply a wet blanket to the throat of the chimney, or over the whole front of the fire-place. If there happens to be a chimney-board, or a register, apply the same immediately; and having, by that means, stopped thc draught of air from below, the burning soot will be put out as completely as a candle is put out by an extinguisher, which acts exactly upon the same principle. FIRE Cocks. S. The churchwardens in London, and within the bills of mortality, are to fix fire cocks at proper distances in streets, and keep a large engine and hand-engine for extinguishing fire, under a penalty of £10. stat. 6. Ann. c. 31. FIRE Engine, is the name commonly given to a machine, by which water is thrown upon fires in order to extinguish them. Various machines have, at different times, been contrived for this purpose; but the most essential particulars in a few of them we can only here describe. The usual construction of the fire-engine, after the improvements were made in it by Newsham, was nearly that which is exhibited in the annexed - figure, and which represents a vertical section of the engine, which is in fact but two forcing pumps communicating with a \º large air vessel. The motion * of the water is effected by the pressure of the atmosphere, the force of men acting upon the extremities H', H", of a lever, and thence giving mo- tion to the pistons S and R, and by the elasticity of con- densed air, in the following manner:—When the piston R is raised, a vacuum would be º made in the barrel TU, if the water did not follow the piston R, from the inferior canal E M, (through the valve H,) which rises through the tube EF, im- mersed in the water of a vessel by the pressure of the atmo- sphere on its surface. The water of the barrel TU, by the succeeding depression of the piston R, shuts the valve H, and is forced, through the superior canal O N, to enter by the valve I, into the air-véssel ab c d ; and the like being done alternately by the other barrel W X, and its piston S, the air-vessel is, by these means, continually filling with water, which compresses the air on the surface of the water in that vessel, and propor- tionally augments its spring'; which at length is so far increased as to re-act with great force on the surface YZ of the sub- jacent water, and compel it to ascend through the small tube ef to the stop-cock pg, where upon turning the cockp the water is suffered to pass through a pipe h fixed to a ball and socket; from the orifice of which it issues with a great velocity, in a continued stream, to a considerable height or distance; and it is usually kept from diverging too soon in its progress by means of a long series of flexible leather pipes, properly joined together, and known among the firemen by the name of the hose. Newsham contrived his engines in such a manner, that part of the men who work them exert their force by treading, which is more effectual than any other way that men can work at such engines; the whole weight of the body being sufficiently thrown on the forces of the pumps; and even part of a man’s strength may be added to the weight by means of horizontal pieces, to which he can apply his hands when he is treading; whereas, by applying the hands to move levers or turn winches, the power must act very unequally. This is the reason why with the same number of men he has generally thrown water further, higher, and in greater quantities, with the same sized engines, than other engineers who have tried their engines against his. Yet the combination of human weight and F I R." F I R. 309. DICTIONARY OF MECHANICAL SCIENCE. strength here recommended has rarely been practised in any subsequent fire-engines, or indeed in any machines whatever, except the ingenious walking crane of Hardie. The chief artifice in the engine according to the construction just described, is the contrivance to produce a continual stream, which is done by the compression and proportional elasticity of air in the barrel a b c d, called the air-vessel. For the air, being an elastic fluid, will be susceptible of compression in any degree by the water forced in through the valves at I, K; and since the force of the air's spring will always be inversely as the space it possesses, it follows that when the air-vessel is half full of water, the air will be compressed into half the space it possessed at first, and therefore its spring will be twice as great as at first. But this spring at first was equal to the pressure of the atmosphere on the same surface; for if it were not, it could not have sustained or resisted the pressure of the atmosphere which stood over it, and consequently could not have filled the vessel before the water was driven in, which yet we find it did, and maintained an equilibrium with the common air. The vessel then being half filled with water, or the air compressed into half the first space, its spring will in this case be equal to twice the pressure of the atmosphere; and there- fore when the stop-cock at p is turned, the air within, pressing on the subjacent water with twice the force it meets with from the external air in the pipe ef, will cause the water to spout out of the engine to the height of 32 or 33 feet, if the friction is not too great. When the air-vessel is two-thirds full of water, the air takes up one-third part, whence its spring will be three times as great as that of the common air, and it will project the water with twice the common atmospheric pressure, consequently it will rise to the height of 62 or 64 feet. When the air-vessel is three- fourths full of water, the air will be compressed into its one- fourth part, and so will protrude the water with three times the atmospheric pressure, and carry it to the height of 96 or 99 feet.—Dr. Gregory's Mech. Various alterations and improvements have been made from time to time in the construction of fire-engines, by Bramah, Dickenson, Simpkin, Rowntree, and Phillips, who have secured their inventions from infringement by patents. Of Furst's engine for extinguishing fires, the following is a short descrip- tion:—From a platform rises an upright pole or mast, of such height as may be judged necessary; a gaft slides upon it in an ascending direction, and along both is conveyed the leather hose from the engine. The branch or nose-pipe of the engine projects at the extremity of the gaft; towards which an iron frame is fixed, whence two chains are suspended; and from these hang ropes, which serve to give an horizontal direction to the branch; while other ropes, that run through proper pulleys, and are thus conveyed down the mast, serve likewise to com- municate a vertical motion to it. By these means, the branch or nose-pipe of the engine is conducted into the window of any room where the fire more immediately rages; and the effect of the water discharged is applied in the most efficacious manner to the extinguishing of the flames. A cheap and simple fire-engine is that invented in America by Ben. Dearborn, of which the following are the particulars: A B and CD, in the figure, are the edges of two planks, con- fined by 4 bolts; . --> a b and cd are tº: ==~ : two cylindrical barrels, in each of which a pis- ton, with a valve, is fastened to the speare, and 4-### is moved up and down alter- nately by the motion of the arms E. E. Be- neath each bar- rel a hole is made through - the plank A B, which is covered with a valve. The arms EE are suspended on the common centre f; there are also arms * *º -- ;:º- tº------e-r-s-a--- hill;º:::::::::::grº- parallel to these on the opposite side ; g g are the ends of handles which are fastened across the ends of the arms. At ſt a bolt goes across from arm to arm, to which the piece ik is affixed, and on which it plays: the lower end of this piece is fastened to the top of the spear e. G. lf is a standard for the purpose of supporting the arms, to which there is a correspon- dent one on the opposite side; both are notched into the edges of the planks, where they are secured by a bolt, which passes through them at l, and has a nut or fore-lock on the opposite side. HI, HI, are square braces, answering the purpose of ducts, through which the water ascends from the barrels, passing through the plank at m. K. L., KL, are irons in the form of a staple, in order to confine the braces: the lower ends of these irons meet, and are secured by a bolt passing through them, and M N n o, which is a piece that goes up through a mortise in the centre of the planks. This piece is square from the lower end, till it reaches the top of the braces, whence they become cylindrical to the top, the upper end being perforated sufficiently low down, in order to communicate with the braces. O P is an iron ring that surrounds the tube, and has two shanks which ascend through the head, which screws on the top at p q ; rs is a ferule nailed round the tube. The annexed figure is the same en- gine; the arms and standards being taken off, in order to delineate more clearly the mode of securing the braces; an object which is com- pletely effected by a wedge driven into the mortise a ; beneath the up- per plank b is a hole for admitting a passage to the bolt, which secures the standards. In this figure a side view of the head is given, with the pipe in a perpendicular direction. The machine is confined within a box, set on wheels, as in the com- mon fire-engines. The whole is made of wood, excepting the spears • of the pumps, and a few bolts, &c. The advantages of this machine are, that it can be made in any place where common pumps are manufactured; that the interior work will not exceed one-fourth of the price of those which are constructed on the usual plan; and that they are incomparably more easy to work than the common ones; cir- cumstances which strongly recommend the American fire- engine to the attention of the public.—Gregory's Mechan. FIRE-Escape, a machine for removing persons from the upper stories of houses on fire, consists of a pole, a rope, and a basket. The pole is of fir, or a common scaffold pole, of any convenient length, from 36 to 46 feet. The diameter at bottom, or greatest end, about five inches; and at the top, or smallest end, about three inches. At three feet from the top is a mor- tise through the pole, and a pulley fixed to it of nearly the same diameter with the pole in that part. The rope is about. three-quarters of an inch diameter, and twice the length of the pole, with a spring-hook at one end, to pass through the ring in the handle of the basket when used: it is put through the mortise over the pulley, and then drawn tight on each side to near the bottom of the pole, and made fast there till wanted. The basket should be of strong wicker-work, three feet and a half long, two feet and a half wide, rounded off at the corners, and four feet deep, rounding every way at the bottom. To the top of the basket is fixed a strong iron curve or handle, with an eye or ring in the middle; and to one side of the basket, near the top, is fixed a small cord, or guide-rope, of about the length of the pole. When the pole is raised, and set against a house over the window from which any persons are to escape, the manner of using it is so plain and obvious, that it need not be described. The most convenient distance from the house for the foot of the pole to stand, where practicable, is about 12 or 14 feet. If two strong iron straps, about three feet long, riveted to a bar cross, and spreading about 14 inches at the foot, were fixed at the bottom of the pole, this would prevent its turning round or slipping on the pavement: and if a strong iron hoop, or ferule, riveted (or welded) to a semicircular piece of iron spreading about 12 inches, and pointed at the ends, 4 K 310 F I R. DICTIONARY OF MECHANICAL SCIENCE. F I R. were fixed on at the top of the pole, it would prevent its sliding against the wall. When these two last-mentioned irons are fixed on, they give the pole all the steadiness of a ladder; and because it is not easy, except to persons who have been used to it, to raise and set upright a pole of 40 feet or more in length, it will be convenient to have two small poles or spars of about two inches diameter, fixed to the sides of the great pole at about two or three feet above the middle of it, by iron eyes riveted to two plates, so as to turn every way; the lower end of these spars to reach within a foot of the bottom of the great pole, and to have ferules and short spikes to prevent sliding on the pavement, when used occasionally to support the great pole like a tripod. There should be two strong ash trundles let through the pole, one at four feet and one at five feet from the bottom, to stand out about eight inches on each side, and to serve as handles, or to twist the rope round in lowering a very heavy weight. If a block and pulley were fixed at about the middle of the rope, above the other pulley, and the other part of the rope made to run double, it would diminish any weight in the basket nearly one-half, and be very useful in drawing any person up to the assistance of those in the chambers, or for removing any effects out of a chamber, which it might be dangerous to attempt by the stairs. It has been proved, by repeated trials, that such a pole as we have been speaking of can be raised from the ground, and two or three persons taken out of the upper windows of a house, and set down safely in the street, in the space of 35 seconds, or a little more than half a minute. Sick and infirm persons, women, children, and many others, who cannot make use of a ladder, may be safely and easily brought down from any of the windows of the house on fire by this machine, and by putting a short pole through the handles of the basket, may be removed to any distance without being taken out of the basket. The pole must always have the rope ready fixed to it, and may be conveniently laid up upon two or three iron hooks under any shade or gateway, and the basket should be kept at the watch-house. When the pole is laid up, the two spars should always be turned towards the head of it. The basket should be made of peeled rods, and the pole and spars painted of a light stone-colour, to render it more visible when used in the night. The fire-escape, exhibited in figure A has the advantages of expedition and security. It consists of a long canvass cradle, attached to a - species of lad- der work, not unlike the shrouds of a ship, and || yet so compact || as to occupy but a small space in ||º the buffette of lºgº the window, where Hº it can be pack- ed up in a case of wood, which || may represent any piece of E - furniture. The - - - - whole is very securely fixed inside of the window-sill, and on an alarm of fire being given, the lowering end may be thrown out into the street, where it will soon be laid hold of by some persons, and brought into the slide or declivity shewn in the figure. A child may then be dropped into the cradle or channel, and will slide into the arms of a person below, with- out any injury, or risk of any. This article is manufactured by H. Rogers, 10, King-street, West Smithfield. Davis's FIRE Escape. This fire-escape is calculated for the use of a parish, and is admirably adapted to the very important end the inventor of it proposed to accomplish. It principally consists of three ladders, A, B, C, as in the following figure, applied to each other by four clasp-irons on the top of each of the two lowermost, which are so contrived, that each ladder may slide into the one beneath it. On the top of the lower- most ladder A, two pulleys are fixed on the inside, over which two ropes a a pass, and are situated between the lower one A, and the middle one B. The ropes are made fast to the bottom of the middle one, on each side, in a proper direction with the pulleys on the top. The uppermost ladder C, is attached to the middle one in the same manner, and on the top of it carries two horn pieces D, made of iron, and turned off at each end, ss. similar to 2 horns, º - - which are four feet wide; their ends are sharp, to pitch on each side of a window, and with their points to hold the ladders steady. The three ladders, when shut down, are about 15 feetin height. They are placed perpendi- cularly in the mid- dle of a framed car- riage E. F., of 9 feet 6 inches long, and 5feet 6inches wide, mounted upon four wheels, F. On each side of the carriage a windlass is af- fixed; that marked G, on the right side of the carriage, is for the four ropes, a a, and bb, fixed two to each ladder A. B. By turning this windlass, the ladders may be wound out from their standing height of fifteen feet, to forty. Over this windlass is a screw, turned by the winch d, by turning which the ladders may be inclined against the house, with all imaginable ease. On the top of the upper ladder C, on the outside, are two pulleys, over which two chains are conducted to the windlass H, on the left side, for the purpose of carrying up a box I. Two boxes of this description travel with the fire- escape, so that in the event of one being filled with small valuables, it may be unhooked, and the other, K, put on, which will save time. The whole of this apparatus may be drawn by one horse, or six men, and when arrived at the scene of danger, may be adjusted in two minutes. If every parish were provided with it, and kept it where it might be brought out without delay, there cannot be a doubt, that many of the serious acci- dents occasioned by fires would be prevented. The key of access to the machine should be kept at some well-known place, and the machine should be brought out at the first alarm of fire, as it offers the ready means of either ascent or descent, and possesses great superiority over any common or parish ladder, which is useless, or next to useless, unless it acciden- tally happens to be of the right height. A method equal to the foregoing, as far as facility of escape is concerned, may be adopted by framing two sides of a ladder similar to a fishing rod; the whole consisting of an indefinite number of pieces of light tough wood, so fitted as to screw the end of one into the socket of the other. The upper end pieces having hooks fixed on them, will enable the inmates to fix the ladder in the sill of a window, and the lower end may be kept steady by persons below, and free from the danger. But after all the methods that might be given, the misfortune is, that in the greater number of such calamities, escape has seldom been effected by such artificial means. FiRe-Flies, a species of flies common in America, of which there are two species. The largest is more than an inch in length, it has two feelers, two wings, and six legs. Under its belly is a circular patch, which, in the dark, shines like a can- dle; and on each side of the head, near the eyes, is a promi- ment, globular, luminous body, in size about one-third larger than a mustard-seed. Each of these bodies is like a living star, emitting a bright, and not small light; since two or three F I R. F. L. R. 311 DICTIONARY OF MECHANICAL SCIENCE. of these animals, put into a glass vessel, afford a light suffi- cient to read by without difficulty, if placed close to the book. When the fly is dead, these bodies will still afford considerable light, though less vivid than before ; and if bruised, and rubbed over the hands or face, they become luminous in the dark, like a board smeared over with English phosphorus. The other kind is not more than half as large as the former: their light proceeds from under their wings, and is seen only when they are elevated, like sparks of fire, appearing or disappearing at every second. FIRE-Place. Economical fire-places should be constructed on the following principles: 1. To place the grate as near the floor as may be. 2. To bring it as forward as may be, con- sistently with the proper situation of the flue of the chimney, which ought to be directly over the fire, and not larger than sufficient to give free passage at all times to the smoke. 3. The mantle-piece, should be as low as possible, without suffering from the heat, or obstructing the proper radiation of it into the room. By these means, a much greater volume of heated air is retained in a room of equal size, than by high grates and large openings. FIRE Ship, a vessel filled with combustible materials, and fitted with grappling-irons, to hook and set fire to the enemy’s ships. Some English vessels, filled with combustible matter, and sent among the Spanish ships composing the Invincible Armada, in 1588, are said to have given rise to the terrible invention of fire-ships. However, Livy informs us, that the Rhodians had invented a kind of fire-ships, which were used in junction with the Roman fleet in their engagements with the Syrians, in the year before Christ 190. Cauldrons of combus- tible and burning materials were hung out at their prows, so that none of the enemy’s ships durst approach them ; these fell on the enemy’s galleys, stuck their beaks into them, and at the same time set them on fire. As there is nothing peculiar in the construction of a modern fire-ship, except the apparatus by which the fire is instantly conveyed from one part to another, and from thence to the enemy, it will be sufficient to describe the fire-room in which the combustibles are enclosed, together with the instruments necessary to grapple the ship intended to be destroyed. The fire-room is built between decks, and extends from the bulk-head at the forecastle to a bulk-head raised behind the main mast. The train enclosed in this apartment is contained in a number of wooden troughs, which intersect each other in different parts of the ship's length, being supported at proper distances by cross-pieces and stanchions. On each side of the ship are six or seven ports about eighteen inches broad, and fifteen inches high, and having their lids to open down- ward, contrary to the usual method. Against every port is placed an iron chamber. These iron chambers are ten inches long and 3 in diameter. They are breeched against a piece of wood fixed across the ports, and let into another a little higher. When loaded, they are almost filled with cornpowder, and have a wooden tompion well driven into their muzzles. They are primed with a small piece of quick-match thrust through their vents into the powder, with a part of it hanging out. When the ports are blown open by means of the iron chambers, the port-lids either fall downwards, or are carried away by the explosion. At the time of firing the ship, the iron chamber blows out the port-lid, and opens a passage for the flame. Immediately under the main and fore-shrouds is fixed a wooden funnel, whose lower end communicates with a fire-barrel, (see the article FIRE-BARRELs,) by which the flame passing through the funnel is conducted to the shrouds. Between the funnels, which are likewise called fire-trunks, are two scuttles, or small holes, in the upper deck, serving also to let out the flames. Both funnels must be stopped with plugs, and have sail-cloth or canvass nailed close over them, to prevent any accident happening from above to the combustibles laid below. The ports, funnels, and scuttles, not only communicate the flames to the outside and upper-works of the ship, and her rigging, but likewise open a passage for the inward air con- fined in the fire-room, which is thereby expanded so as to force impetuously through those outlets, and prevent the blow- ing up of the decks, which must of necessity happen from such sudden and violent refraction of the air as will then be pro- duced. On each side of the buik-head behind, is cut a hole on sufficient size to admit a trough of the same dimensions as the others. A leading trough, whose foremost end communicates with another trough within the fire-room, is laid close to this opening, from whence it extends obliquely to a sally-port cut in the ship's side. The decks and troughs are well covered with melted rosin. At the time of firing either of the leading troughs, the flame is immediately conveyed to the opposite side of the ship, whereby both sides burn together. The lieutenant's cabin is on the starboard-side, and the master's cabin on the larboard; the captain's cabin is sepa- rated from these by the bulk-head. The stores for a fire-ship of 150 tons are— - 8 Fire-barrels. 1 Quick-match barrel, 12 Iron chambers 30 Dipped curtains. 209 Bavins, single dipped. 150 Long reeds, single dipped. 24 Port-fires. 75 Short reeds, single dipped. 33 Priming composition bar- 75 Shortreeds, double dipped. rels. 60 Hand grenadoes. - The quantity of composition for preparing the stores of a fire-ship is exhibited in the following statement: r For 8 barrels.-Corn-powder, 960 lbs. ; pitch, 480; tallow, 80. For 3} barrels, priming composition.—Saltpetre, 175 lbs. ; sulphur, 140; corn-powder, 350; rosin, 21 ; oil, 11 pts. For the curtains, bavins, and reeds for the ship, and sulphur for salting them.—Sulphur, 200 lbs. ; pitch, 350; rosin, 175; tallow, 50 ; tar, 25. - - Total.—Saltpetre, 175 lbs. ; sulphur, 340 lbs. ; corn-powder, 1310 lbs. ; pitch, 830 lbs. ; rosin, 196 lbs. ; tallow, 130 lbs. ; tar, 25 lbs. ; oil, 11 pts. - For reeds for the barrels, 160 lbs. being one-fifth of the whole of the last article. - The reeds are made up in small bundles of about a foot in circumference, cut even at both ends, and tied together in two places. They are distinguished into two kinds, viz. the long and short; the former of which are four feet, and the latter two feet five inches in length. One part of them are singly dipped, i. e. at one end; the rest are dipped at both ends in a kettle of melted composition, and being immersed about seven or eight inches in this preparation and then drained, they are sprinkled over with pulverized sulphur upon a tanned hide. The bavins are made of birch, heath, or other brushwood, which is tough and readily kindled. They are usually two or three feet in length, and have all their bushways lying one way, the other ends being tied together with small cords. They are dipped in composition at the bush ends, whose branches are afterwards confined by the hand, to prevent them from break- ing off by moving about; and also to make them burn more fiercely. After being dipped in the same manner as the reeds, they are also sprinkled with sulphur. Quick-match is formed of three strands, drawn into length, and dipped into a boiling composition of white-wine-vinegar, saltpetre, and meal or corn powder. After this immersion it is taken out hot and laid in a trough, where some mealed pow- der, moistened with spirits of wine, is thoroughly incorporated with the twists of the cotton, by rolling it about therein. Thus prepared they are taken separately and drawn through mealed powder, then hung upon a line till dried, by which they are fit for immediate service. Port-fires are frequently used by the artillery-men in pre- ference to matches, to set fire to the powder or composition. They are distinguished into wet and dry port-fires. The com- position of the former is saltpetre four, sulphur one, and mealed powder four. When these materials are thoroughly mixed and sifted, the whole is to be moistened with a little linseed oil, and rubbed between the hands till the oil is imbibed by the composition. The preparation for dry port-fires is salt- petre four, sulphur one, mealed powder two, and antimony one. These compositions are driven into small paper cases, to be used whenever necessary. Four of the eight fire-barrels (according to the stores men- tioned above for a fire-ship of 150 tons) are placed under the four fire-trunks, and the other four between them, two on each side of the fire-scuttles, where they are securely cleated to the deck. The longest reeds are put into the fore and aft troughs and tied down; the shortest reeds are laid in the troughs wº, 312 F I R. F I S DICTIONARY OF MECHANICAL SCIENCE. athwart, and tied down also. The bavins, dipped at one end, are tied fast to the troughs over the reeds, and the curtains are nailed up to the beams in equal quantities on each side of the fire-room. The remainder of the reeds are placed in a position nearly upright, at all the angles of every square in the fire-room, and there laid down. If any reeds are left, they are to be put round the fire-barrels and other vacant places, and there tied fast. Instructions to Prime.—Take up all your reeds, one after another, and strew a little composition at the bottom of all the troughs under the reeds, and then tie them gently down again: next strew composition upon the upper part of the reeds throughout the fire-room, and upon the said composition lay double quick-match upon all the reeds in all the troughs: the remainder of the composition strew over all the fire-room, and then lay your bavins loose. Cast off all the covers of the fire-barrels, and hang the quick- match loose over their sides, and place leaders of quick-match from the ends into the barrels, and from thence into the vent of the chambers in such a manner as to be certain of their blowing open their ports, and setting fire to the barrels. Two troughs of communication from each door of the fire-room to the sally-ports, must be laid with a strong leader of quick- match four or five times double; also a cross piece to go from the sally-port, when the ship is fixed, to the communication- trough, laid with leaders of quick-match, that the fire may be communicated to both sides at once. What quick-match is left, place so that the fire may be communicated to all parts of the room at once, especially about the ports and fire-barrels, and see that the chambers are well and fresh primed. The port-fires used for firing the ship, burn about twelve minutes; great care must therefore be taken to have no pow- der on board when the ship is fired. The sheer-hooks are fitted so as to fasten on the yard-arms of the fire-ship, where they hook the enemy’s rigging. The fire-grapplings are either fixed on the yard-arms or thrown by hand, having a chain to confine the ships together, or fasten those instruments which are necessary. When the commanding officer of a fleet displays the signal to prepare for action, the fire-ships fix their sheer-hooks, and dispose their grapplings in readiness. The battle being begun, they proceed immediately to prime and prepare their fire- works. When they are ready for grappling, they inform the admiral thereof by a particular signal. To avoid being disabled by the enemy's cannon during a general engagement; the fire-ships continue sufficiently dis- tant from their line of battle, either to windward or to lee- ward. They cautiously shun the openings or intervals of the line where they would be directly exposed to the enemy’s fire, from which they are covered by lying on the opposite side of their own ships. They are attentively to observe the signals of the admiral or his seconds, in order to put their designs im- mediately in execution. Although no ship of the line should be previously appointed to protect any fire-ship except a few of the smallest particularly destined to this service, yet the ship before whom she passes in order to approach the enemy, should escort her thither, and assist her with an armed boat, or whatever succour may be necessary in her situation. The captain of the fire-ship should himself be particularly attentive that the above instructions are punctually executed, and that the yards may be so braced, when he falls alongside the ship intended to be destroyed, that the sheer-hooks and grapplings fastened to the yard-arms, &c., may effectually hook the enemy. He is expected to be the last person who quits the vessel, and being furnished with every necessary assist- ance and support, his reputation will greatly depend on the success of his enterprize. FIRE, Wild, a factitious fire, which burns even under water. It is composed of sulphur, pitch, nitre, and various other com- bustible materials; and is very hard to extinguish. Chemistry, however, has supplied a still more destructive kind of wild-fire, in the union of nitrous acid with oil of turpentine. These two liquids, separately, are perfectly cold; but when suddenly mixed, produce a flame not easily extinguished. To make Artificial Fire-works.--Artificial fire-works are of two kinds, those made of gunpowder, nitre, and other inflam- º mable substances and filings of the metals, camphor, &c. and those produced by hydrogen or inflammable air. Those made with gunpowder are well known, and are called rockets, fire- wheels, tourbillons, &c. Of theso, the most usual are rockets; which are made by ramming into strong cylindrical paper cases put into wooden moulds, like small hollow columns, powdered gunpowder, or the ingredients of which it is com- posed, viz. saltpetre, sulphur, and charcoal, very dry. To represent a fiery rain falling from the rocket, mix among your charge a composition of powdered glass, filings of iron, and saw-dust: this shower is called the peacock's tail, on account of the various colours exhibited. Camphor mixed with the charge, produces white or pale fire; resin a reddish colour, sulphur a blue, sal ammoniac a green, antimony a reddish yel- low, ivory shavings a silvery white, pitch a deep or dark coloured fire, and steel filings, beautiful coruscations and sparks. Sticks are fastened to the rockets, by yhich they are projected into the air, after they have been lightº: the charge burning with great intensity at one end, acts upon the air, which, in its turn, re-acts upon the rocket, and causes it to ascend, on the same principle as a boat is put off by a man in it, who pushes against the shore with a boat-hook. Fire-works by means of inflammable air are the most elegant; and being free from smell or smoke, may be exhibited in a room without any disagreeable effect. - FIRING, in the Military art, denotes the discharge of small arms by platoons, standing, advancing, or retreating ; or in oblique or hedge firing. Platoons fire from the right and left alternately, except the centre platoon of the regiment, which being in charge of the colours, remains loaded. Hedge firing is by two deep ; oblique is either to the right or left, according to the situation of the object. Parapet and banquette firing depend on various jºice: position of the enemy. Square firing is performed in hollow square, when each front is divided into four divisions, and the flanks of the square being the weakest, are covered by four platoons of grenadiers. FIRKIN, an English measure of capacity, for things liquid, being the fourth-part of the barrel. It contains eight gallons of ale, soap or herrings, in weight 50lbs. ; and nine of beer. FIRLOT, a dry measure used in Scotland, containing 21% pints of that country; the barley firlot has, however, 31 standard pints in it. The wheat firlot contains 2211 cubic inches; the English bushel 2178 cubical inches. The Scotch wheat firlot is, therefore, 33 cubical inches larger than the English bushel. - FIRMAMENT (firmamentum, Latin). This word has been used with great latitude, as well by the sacred writers, as by poets and astronomers. Some old astronomers consider the orb of the fixed stars as the firmament; but in Scripture, and in common language, it is used for the middle regions, or the space or expanse appearing like an immense concave hemi- sphere. Many astronomers, both ancient and modern, ac- counted the firmament a fluid matter; but those who gave it the name of firmament must have considered it as a solid. FIRMNESS, in Philosophy, denotes the consistence of a body, or that state wherein its sensible parts cohere, or are united together, so that a motion of one part induces a motion of the rest. In which sense firmness stands opposed to fluidity. See CoHesion. - FIRST FRUITs, in the church of England, are the profits of every spiritual benefice for the first year, according to the valuation thereof in the king's books. FISC, in Civil Law, the treasury of a prince or state, or that to which all things due to the public do fall. Hence, the Fiscal is the officer who has charge of the said treasury. FISH, a machine employed to hoist and draw up the flukes of a ship's anchor towards the top of the bow, in order to stow it after it has been catted; it is composed of four parts, viz. the pendant, the block, the hook, and the tackle, which, with their uses, are described under the article DAVIT. Fish, is also a long piece of timber, convex on one side and concave on the other, used to strengthen the lower masts, or the yards when they are sprung, or have received some dam- age in battle, or in tempestuous weather, &c. to effect which they are well secured by stout rope called woolding. - - Fish Gig, an instrument used to strike fish at sea; it cone F 1 S F i S 313 DICTIONARY OF MECHANICAL SCIENCE sists of a staff with three, four, or more barbed prongs of steel, and a line fastened to the end on which the prongs are fixed; to the other end is fitted a piece of lead, which gives additional force to the stroke, and causes the points to turn upwards after the fish is penetrated. Fish Room, a space between the after-hold and the spirit- room. FISHERY, a place where great numbers of fish are caught, as salmon in the lochs of Scotland, herrings among the Hebrides, pilchards along the coast of Cornwall, cod on the banks of Newfoundland, and whales in Greenland. Free Fishery, in Law, is a royal franchise—an exclusive right of fishing in a public river; though some have considered this free fishing not as a royal grant. Fishery denotes also the commerce of fish, more particularly the catching of them for sale. To encourage the herring fisheries among the Hebrides, from the time of James V. of Scotland till the year 1825, both the Scots and lish governments protected, patronized, and even allowed bounties to the herring fishers of these kingdoms; but these bounties are now withdrawn, because there is ample capital, and a sufficient spirit of competition to continue them as private sources of emolument, without the attention of his majesty's ministers. Cod Fishery, on the banks of Newfound- land, is of two kinds; the one green or white cod, and the other dried or cured cod—each being the same species of fish, only differently cured and prepared for the market. The former are salted in barrels for use; the latter salted, and then dried in the sun, and smoked. The best season is, from the beginning of February to the end of April. The roes and tongues of cod fish are preserved separately, and the livers melted into oil. The Lobster Fishery, along the British channel, and on the coast of Norway, whence this shell fish are brought to London for sale; also in the Frith of Edinburgh, and on the coast of Northumberland. By law, no lobster is to be taken under 8 inches long, from the peak of the nose to the end of the mid- dle fin of the tail; nor dare the fishermen take any on the coast of Scotland from the 1st of June to the 1st of September, by 9 Geo. II. cap. 33. Mackerel Fishery, on the French and English coasts, is usually from April to August, and the fish are taken with the line, or by means of nets. The mackerel fishery is an object of great commercial im- portance to the inhabitants of most of the countries on the shores of which these fish abound. During the summer season they approach our coasts in immense shoals, and are generally caught in what are called seine nets. From June to August many of our markets are supplied with them, but as they become putrid sooner than most other fish, they cannot be carried to any great distance, nor be kept for any great length of time. On this account it is that they are allowed to be sold in the streets of London on Sundays, and in Catholic countries on Sundays and festivals. When quite fresh, mackerel are an excellest fish for the table, and are in best season from May to July. Both in Italy and in England they are often pickled with vinegar and spices, and sometimes with bay leaves inter- mixed. By the inhabitants of many parts of the north of Europe they are salted; and in this state constitute a cheap and very important article of subsistence. In Scotland they are frequently cured in the same manner as herrings. The Oyster Fishery, at Colchester, in Essex, Milton and Feversham in Kent, the Isle of Wight, the swales of the Med- way, and Tenby on the coast of Wales, is carried on from September till May. The best oysters are of a middle size; they are dragged up by a net, (with an iron scraper at the mouth,) which is dragged by a rope from a boat over the beds; and then stored in large pits formed for the purpose, and furnished with sluices, through which at spring tides the salt water is suffered to flow. In these pits they acquire their full quality, and become fit for the table in six or eight weeks. The most delicious oysters are considered to be those which are fattened in the salt-water creeks near Milton and Colches- ter. Oysters are out of season during the summer time, the period at which they deposit their spawn, and which commences in the month of April. Each spawn has the appearance of a drop of candle-grease, and adheres to rocks, stones, or other substances on which it happens to be deposited. In some oyster beds old shells, pieces of wood, &c. under the denomina- tion of cultch, are purposely thrown in to receive the spawn. From these, in the month of May, the oyster fishers are allowed to separate the spawn for the purpose of transferring it to other beds; but they are required, under certain penalties, to throw the cultch in again, that the beds may be preserved for the future; unless the spawn should be so small as not with safety to be separable from the cultch. Oysters are considered to be first fit for the table when about a year and half old; and they are among the few animals which in Europe are not merely eaten raw, but even in a living state. Oysters are also eaten cooked in various ways, as sauce to different kinds of fish, and pickled. The shells, like those of other testaceous animals, consist of calcareous earth in combination with animal glue; and by calcination, they yield a pure kind of quick lime. In this state they are not only useful as lime, but are also fre- quently employed by stationers and attorneys as pounce for rubbing upon parchment previously to its being written upon. The Pilchard Fishery, on the coasts of Cornwall and Devon- shire, from June to September; and on the coast of Bretagne in France, and the coast of Dalmatia, is a very lucrative con- cern, from the great abundance of these fish that are taken. The Salmon Fishery, in the Tweed, the Clyde, the Tay, the Dee, the Don, the Spay, the Tyne, the Trent, the Severn, and the Ban, &c. is at its height in the summer season; the hotter the weather, the more plentiful generally the fish. The Sturgeon Fishery, in the Volga, the Caspian sea, and the Tunny Fishery, in the Mediterranean, employ a great number of men. The Turbot Fishery, on the Dutch coast, finds a profitable sale in London. FISHES, in Heraldry, are emblems of silence and watchful- mess, and are borne either upright, embowed, extended, endorsed respecting each other, surmounting one another, &c. Or they may be cant emblems, as a salmon borne by a person of that name, the fish being perpendicular; a cod, by the Cod family; a herring, by the Herrings, &c. Fishes. To define these would be superfluous; but their general physiology deserves attention. Like amphibious ani- mals, the hearts of fishes are unilocular, or consist but of one cavity, and their blood is less warm than that of quadrupeds and birds. The organs of breathing are the gills, equivalent to the lungs in man; and these consist of numerous blood- vessels. The generality of fishes are covered with scales, analogous to the hair of quadrupeds and the feathers of birds. The fins, the chief instruments of motion, consist of a cer- tain number of elastic rays of processes, either of one single piece in the form of a spine, or of jointed pieces. The strong or spiny rays are placed at the fore part of the fin, and the soft or jointed rays towards the back part. By the various flexures of these organs, the movements of fishes are con- ducted; the perpendicular fins, situated on the back or upper part of the animal, keeping the body in equilibrio, while the tail operates as a rudder at the stern of a vessel, and the side or breast-fins as oars. The stomach is large, the intestines far shorter than in quadrupeds and birds: and the liver is very large, usually placed on the left side. The air bladder, or swimming bladder, is a very highly curious and important organ, lying closely beneath the backbone, and provided with a very strong muscular coat, which gives it the power of contracting at the pleasure of the fish, so as to con- dense the air with which it is filled, and thus enable the ani- mal to descend to any depth, and again to ascend by being restored to its largest size. Some fishes are destitute of the air-bladder, yet remain always at the bottom; as the whole tribe of flat-fish. The teeth are, in some tribes, large and strong, in others, very small; in some, sharp; in others, obtuse; in some, numerous; and in others, few. Sometimes they are placed in the jaws; sometimes in the palate or tongue; or, even at the entrance of the stomach. The eyes are, in general, large, flattened, or less convex than in quadrupeds and birds. In return, the central part of the eye, or what is called the crystalline humour, is of a globular shape, to give the animal the necessary power of vision, and to compensate for the comparative flatness of the cornea. The organ of smelling, in fishes, is large; and they have the 4 L 314 F 1 Y. F. L. A pictionary of MECHANICAL SCIENCE. power of contracting or dilating it at pleasure. This sense is extremely acute. The organ of hearing differs, in some par- ticulars, from that in other animals, and is modified according to the nature of the fish. They are entirely destitute of voice. The particular kind of sound or chirp, which some tribes are observed to make, on being first taken out of the water, is entirely owing to the sudden expulsion of air from their inter- mal cavities. The greater number of fishes are oviparous, pro- ducing soft eggs, usually known by the name of spawn. There have been 200,000 ova or eggs found in a carp; in a perch, weighing one pound two ounces, 69,216; in a carp of eighteen inches, 342,144; in a sturgeon of one hundred and sixty pounds, there was the enormous number of 1,467,500 !!! The age of fish is determinable by the number of concentric circles of the vertebrae or joints of the back-bone. In the Linnaean arrange- ment of fishes, the under or belly-fins are termed ventral, and are considered analogous to the feet in quadrupeds; and it is from the presence or absence of the fins, that the divisions are instituted. Far as creation's ample range extends, The scale of sensual, mental powers, ascends: Mark, how it mounts to man's imperial race, From the green myriads in the peopled grass: What modes of sight betwixt each wide extreme, The mole's dim curtain, and the lynx’s beam : Of smell, the headlong lioness between, And hound sagacious, on the tainted green: Of hearing, from the life that fills the flood, To that which warbles thro’ the vernal wood The spider's touch, how exquisitively fine! Feels at each thread, and lives along the line: In the nice bee, what sense so subtly true! From poisonous herbs extracts the healing dew : How instinct varies in the groveling swine, Compard, half-reasoning elephant, with thine! "Twixt that, and reason, what a nice barrier' For ever separate, yet for ever near ! The fishes are divided into six orders, namely; 1. Apodes: 2. Jujulares: 3. Thoracici: 4. Abdominales: 5. Branchiostegi: 6. Chondropterygii. 1. Apodal fish have bony gills; and no ventral fins, as the eel. 2. Jugular fish have bony gills; and the ventral fins situated directly under the pectoral fins, as the cod, haddock, and whiting. 3. Thoracic fish have bony gills; and the ven- tral fins situated directly under the pectoral fins, as the perch and mackerel. 4. Abdominal fish have bony gills; and the ventral fins on the belly behind the pectoral fins, as the salmon, herring, and carp. 5. Branchiostegeous fish have their gills destitute of bony rays, as the sucker. 6. Chrondropterygeous fish have cartilaginous fins, as the sturgeon, shark, and skate. FISHING, see ANGLING. With respect to the right of fish- ing, and the property of fish, where the lord of the manor hath land on both sides of a river, it is good evidence that he hath a right of fishing; but where a river ebbs and flows, and is an arm of the sea, then it is common to all. Thus in the Severn, &c. the soil belongs to the owners of the land on each side, and the soil of the river is in the king, but the fishing is common to all. He who is owner of a private river, or pond, hath a property in the fish; and there needs no privilege to make a fishpond. FISSURES, in the History of the Earth, are certain erup- tions that horizontally or parallely divide the several strata of which the body of the terrestrial globe is composed. FISTULA, in Surgery, a deep, narrow, and callous ulcer, generally arising from abscesses, chiefly in the arms. FISTULARIA, pipe fish, a genus of the order abdominales, grows to the length of three or four feet, and is of the shape of an eel. FITTER, in Chemistry, any instrument or machine, whose use and effect with regard to liquids is the same that the sieve or scarce has in dry matters. Water is freed from its impuri- ties by basins of porous stone. FITTING-OUT, the act of furnishing a ship with sufficient masts, sails, yards, ammunition, artillery, cordage, anchors, provisions, stores, and men, for the voyage or purpose to which she is appointed. FIXED Bodies, generally deucte those bodies which neither fire nor any corrosive has such an effect on, as to reduce or resolve them into their component elements, or absolutely to destroy them. Of fixed bodies, the principal are gold, platina, silver, precious stones, particularly the diamond, salts, &c. Fixed Ecliptic, a certain imaginary plane, which never changes its position in the heavens from the action of any of the parts of the solar system on each other; but, like a centre of inertia, remains immoveably fixed. The existence of such a plane is demonstrated by Laplace, who has shewn the me- thod of determining it from the situations, velocities, masses, &c. of the planets and other bodies. See Zodiac. Fixed Signs of the Zodiae, an arbitrary denomination which some astronomers have given to the signs Taurus, Leo, Scor- pio, and Aquarius. The particular corresponding season being supposed most fixed when the sun is in those signs. Fixed Stars, are those which constantly maintain the same relative position with regard to each other, in distinction to the planets and comets which are constan nging their relative positions. See Constellation, Hemisphere, and STAR. FIXITY, or Fixed Ness, in Philosophy, the quality of a body which denominates and renders it fixed; or a property which enables it to endure fire, and other violent agents. A body may be said to be fixed in two respects; viz. 1. When, on being exposed to the action of fire, or a corrosive men- struum, its particles are indeed separated, and the body ren- dered fluid, but without being resolved into its first elements: and, 2. When the body sustains the active force of the fire, or menstruums, whilst its integral parts are not carried off by fume. Each kind of fixity is the result of a strong or inti- mate cohesion between the particles of the body. FLAG, a certain banner by which an admiral is distinguished at sea from the inferior ships of his squadron; also the colours by which one nation is distinguished from another. In the British navy, flags are either red, white, or blue, and are dis- played from the top of the main-mast, fore-mast, or mizzen- mast, according to the rank of the admiral. The first flag in Great Britain is the royal standard, which is only to be hoisted when the king or queen is on board the vessel; the second is that of the anchor of hope, which charac- terizes the lord high admiral, or lords commissioners of the admiralty; and the third is the union flag, appropriated to the admiral of the fleet, who is the first officer under the lord high admiral. The navy-board, custom-house, &c. have each their respective flags. When the flag is displayed at the main-top-gallant-mast- head, the officer distinguished thereby is known to be an admiral; when from the fore-top-gallant-mast-head, a vice- admiral; and when from the mizzen-top-gallant-mast-head, a rear-admiral; the next flag after the union, is white at the main; and the last, which characterizes an admiral, is blue at the same mast-head. For a vice-admiral the first flag is red, the second white, and the third blue, at the fore-top-gallant- mast-head. The same order is observed with regard to rear- admirals, whose flags are displayed at the mizzen-top-gallant- mast-head; the lowest flag in our navy is accordingly blue at the mizzen. All the white flags have a red St. George's cross in them, in order the more readily to be distinguished from the French white flag with a white cross. Besides the national flag, merchant ships frequently bear lesser on the mizzen-masts, with the arms of the city where the master ordinarily resides, and on the fore-mast with the arms of the place where the person who freights them lives. When a council of war is held at sea, if it be on board the admiral, they hang a flag on the main-shrouds; if in the vice- admiral, in the fore-shrouds; and if in the rear-admiral, in the mizzen-shrouds. The flags borne on the mizzen are particularly called Gallants. To heave out the flag, is to put out or hang abroad the flag. To hang out the white flag, is to call for quarter; or it shews when a vessel arrives on a coast that it has no hostile inten- tion, but comes to trade, or the like. To hang out the red flag, is to give a signal of defiance and battle. To lower, or strike the flag, is to pull it down upon the cap, or to take it in, out of the respect or submission due from all ships or fleets inferior to those any way justly their superiors. To lower or strike the flag in an engagement, is a sign of yielding. F. L. A. F. L. A. 315 DICTIONARY OF MECHANICAL SCIENCE. The way to lead a ship in triumph, is to tie the flags to the shrouds, or the gallery in the hind part of the ship, and let them hang down towards the water, and tow the vessels by the stern. Livy relates that this was the way the Romans used those of Carthage. Flag Officer, a term synonymous to admiral. FLAG Ship, a ship in which an admiral's flag is displayed. FLAG Staff, is generally a continuation of the top-gallant- mast above the top-gallant rigging, but is sometimes, espe- cially in guard-ships, a spar, occupying the place of the top- gallant-mast, and is only of use to display the flag or pendant; when it is a continuation of the top-gallant-mast, it is frequently termed the royal mast. FLAGEOLET, a little flute, used chiefly by shepherds and country people. FLAIL, rument for thrashing corn, that consists of, hich the labourer holds in his hand ; 2. the which strikes the corn ; 3. the caplins, or mºs that bind the hand-staff and swiple; 4. the middle band, being the leathern thong, or fish-skin, that ties the caplins together. FLAIR, is a phrase at sea: when a ship being housed in near the water so that the work hangs over a little too much, and thus is let out broader aloft than the due proportion will allow, the seamen say that the work doth flair over. FLAKE, a sort of platform made of hurdles, used for drying codfish in Newfoundland; they are usually placed near the shores of fishing-harbours. Flake signifies also a small stage hung over a ship's side to caulk or repair any breach. We speak also of a flake of snow. See SNow. FLAMBEAU, a large taper, made of hempen wicks, by pouring melted wax on their top, and letting it run down to the bottom. This done, they ſay them to dry; after which they roll them on a table, and join four of them together by means of a red-hot iron; and then pour on more wax till the flambeau is brought to the size required. Flambeaus are of different lengths, and made either of white or yellow wax. They serve to give light in the streets at night, or on occasion of illumi- nations. - FLAME, the subtlest and brightest part of fuel, ascending above it in a pyramidal or conical figure, and has been con- jectured by Newton to be a vapour red-hot; which, however, seems to be but an imperfect idea. We should rather say, that flame is an instance of combustion, whose colour will be determined by the degree of decomposition which takes place. If it be very imperfect, the most refrangible rays only will appear; if very perfect, all the rays will appear, and the flame will be brilliant in proportion to this perfection. There are flames, however, which consist of burning particles, whose rays have partly escaped before they ascended in the form of vapour; such would be the flame of a red-hot coal, if exposed to such a heat as would gradually disperse it into vapour. When the fire is very low under the furnace of an iron-foun- dery, at the upper orifice of the chimney a red flame of this kind may be seen, which is different from the flame that ap- pears immediately after fresh coals have been thrown on the fire; for, in consequence of adding such a supply to the burn- ing fuel, a vast column of smoke ascends, and forms a medium so thick as to absorb most of the rays excepting the red. FLAMINGO. See Phoenicopterus. FLAMSTEED, a celebrated English astronomer, and the first astronomer royal, was born at Derby, in the year 1646, and very early discovered a great genius and taste for astro- nomical subjects; having, while yet a youth, computed both solar and lunar eclipses, and occultations of the moon and stars. He possessed more zeal and application in the pursuit of scientific knowledge than the first astronomer royal, and scarcely any man ever attain d a higher respect amongst his contemporaries. In common life he was free and easy of access, and pleased with the company of those who, with scientific research, could unite their share in the convivial intercourse of life. Flamsteed's great work on astronomy, in 3 vols. fol. comprises a catalogue of the right ascensions, polar distances, longitudes, and magnitudes of nearly 3000 fixed stars. The preface to this volume contains an account of all the astronomical observations made before his time, with a description of the instruments employed, and much other curious and highly important matter. FLANK, in the Manege, the sides of a horse's buttock; or more properly, the extremities of the belly where the ribs are wanting. In a well-made horse the flanks are full, and the distance short between the last rib and the haunch bone, which is properly the flank. FLANK, in War, the side of a battalion, army, &c. in contra- distinction to front and rear. In Fortification, the part of a bastion which reaches from the curtain to the face. See Bastion. FLANNEL, a woollen stuff, composed of a woof and warp, and woven after the manner of baize. Various theories have been adopted to prove the utility of flannel as an article of dress; it is unquestionably a bad conductor of heat, and on that account very useful in cold weather; this is accounted for from the structure of the stuff; the fibres touch each other very slightly, so that the heat moves slowly through the interstices, which being already filled with air, give little assistance in carrying off the heat. In the town of Rochdale, and the adjacent villages, there are manufactured, every week, of flannels and baizes, about 20,000 pieces, of 46 yards each, making 47,840,000 yards per annum. It is supposed that 17,840,000 yards are exported; the remaining 30 millions of yards are consumed in the United Kingdom, being an average of about 13 yard for each individual. Some good flannels are manufactured in Wales; a few coarse ones at Keswick, and some other towns and villages in the kingdom. A few are manufactured on the Continent, and works for that purpose are now erecting in America; but the whole of the flannels manufactured on the globe, besides those manufactured in Rochdale and its immediate vicinity, are not equal in quantity to those made there. The price of flannels is from 5d. to 3s. per yard; and the average may be stated at from 13d. to 14d. per yard; so that the annual value of the manufacture may be stated at about three millions sterling. The wool costs fully one-half of the wholesale selling price; the oil, labour, and finishing, &c. constitute nearly the other half. FLAT, a level ground lying at a small depth under the sur- face of the sea; otherwise called a Shoal, or Shallow. To FLAT in, the action of drawing in the aftmost clue of a sail towards the middle of a ship, to give the sail the greater power of turning the vessel; thus, if the mizzen or after sails are flatted in, it is evident that the intention is to carry the stern to leeward, and turn the head nearer to the wind ; and if the head-sails are flatted in, the intention is accordingly to make the ship fall off, when, by design or accident, she has come so near the wind as to make the sails shiver; hence— FLAT in forward, is the order to draw in the jib and fore- top-mast stay-sail sheets towards the middle of the ship; this operation is seldom necessary, except in light breezes of wind, when the helm has not sufficient government of the ship. FLAT, in Music, a character, which before a note signifies that the note is to be sung or played half a tone lower than its natural pitch. A double flat is a character compounded of two flats, signifying that the note before which it is placed is to be sung or played two semitones lower than its natural pitch. FLAX DRessing, has for many ages been performed in slow and laborious operations, by means of a mallet, a break, &c. which have been used for preparing the flax for the heckle. The break and scutcher, common in Ireland and Scotland. are inferior to the machinery of mills, among the chief of which is the following, to be found in “Gray's Millwright.” FLAx Mill. (See Plate, Mills.) AA, the great water-wheel fixed upon its shaft, and containing 40 aws or float-boards, to receive the water which communicates motion to the whole machinery. B B, a wheel fastened upon the same axle, hav- ing, as before mentioned, 102 cogs, to drive the wheel C of 25 teeth, which is fixed upon the middle roller, No. 1. The thick part of this roller is fluted, or rather has teeth all round its circumference. These teeth are of an angular form, being broad at their base, and thinner towards their outward extre- mities, which are a little rounded, to prevent them from cutting the flax as it passes through betwixt the rollers. The other two rollers, Nos. 2 and 3, have teeth in them of the same form and size as those in the middle roller, whose teeth, by taking 316 F. L. E. F L 0. DICTIONARY OF MECHANICAL SCIENCE. into those of these two rollers, turn them both round. The rough flax is made up into small parcels, which being intro- duced betwixt the middle and upper rollers, pass round the middle one; and this either having rollers placed on its off- side, or being enclosed by a curved board that turns the flax out betwixt the middle and under rollers, when it is again put in betwixt the middle and upper one, round the same course, until it be sufficiently broken or softened, and prepared for the scutching machine. The bearer in which the gudgeon of the roller No. 1 turns, is fixed in the frame at C.; and the gudgeons of the rollers Nos. 2 and 3 turn in sliders that move up or down in grooves in the frames S. S. The under roller is kept up to the middle one by the weights D D, suspended by two ropes going over two sheaves in the frame S S ; their other ends being fastened to a transverse bearer below the sliders in which the gudgeons of the roller No. 3 turn. The weights D D must be considerably heavier than the under roller and sliders, in order that its teeth may be pressed in betwixt the teeth of No. 1, to bruise the flax when passing between the rollers. The whole weight of the roller No. 2 presses on the flax which passes between it and No. 1. There is also a box fixed on the upper edge of its two sliders to contain a parcel of stones, or lumps of any heavy metal, so that more or less weight can be added to the roller, as is found necessary. OO, is the large frame that supports one end of the shaft which carries the two wheels A, B, and vertical axle FF; on the lower end of which is fixed the pinion turned by the wheel B, and having 10 teeth. In the axle F, are arms upon which the scutchers are fastened with screwed bolts. These scutchers are enclosed in the cylin- drical box EE, having in its curved surface holes or porches at which the handfuls of ſlax are held in, that they may be cleaned by the revolving scutchers. HH, the fall or course of the water. TT, the sluice, machine, and handle, for raising the sluice to let the water on the great wheel. The gudgeons of the axles should all turn in cods or bushes of brass. KK, the side walls of the mill house. G G, doors. L.L., windows. R K, the roof. FLEAM, in Surgery and Farriery, an instrument for letting a horse or other animal blood. FLEECY HostERY, a useful manufacture, in which fine fleeces of wool are interwoven into a cotton piece of the com- mon stocking texture, for making stockings, socks, waistcoats, and other clothing, for persons afflicted with complaints requir- ing warmth, and for common use in cold climates. FLEET, a general name given to the British navy; it also denotes any number of ships, whether designed for war or commerce, keeping company together. The admirals of his majesty’s fleet are classed into three squadrons, viz. the red, white, and blue. When any of these officers are invested with the command of a squadron or detachment of ships of war, the particular ships are distinguished by the colours of their respective squadron: that is to say, the ships of the red squa- dron wear an ensign whose union is displayed on a red field; the ensigns of the white squadron have a white field, and those of the blue squadron a blue field; the union being common to all three. The ships of war, therefore, are occa- sionally annexed to any of the three squadrons, or shifted from one to another. Of whatsoever number a fleet of ships of war is composed, it is usually divided into three squadrons; and these, if nume- rous, are again separated into divisions. The admiral, or principal officer, commands the centre; the vice-admiral, or second in command, superintends the van-guard; and the ope- rations of the rear are directed by the rear-admiral, or the officer next in rank. See the article Division. The disposition of a fleet while proceeding on a voyage will, in some measure, depend on particular circumstances; as the difficulty of navigation; the necessity of despatch, according to the urgency or importance of the expedition; or the expec- tation of an enemy in the passage. The most convenient order is probably to range it into three lines or columns, each of which is parallel to a line close hauled, according to the tack on which the line of battle is designed to be formed. This arrangement is more used than any, because it contains the advantages of every other form without their inconveniences. The fleet being thus more enclosed will more readily observe the signals, and with greater facility form itself into the line of battle; a circumstance which should be observed in every order of sailing. See the article ENGAGEMENT. Merchant-fleets generally take their denomination from the place they are bound to, as the West India fleet, the East India fleet, &c. These in times of peace go in fleets for their mutual protection and assistance: in times of war, besides this secu- rity, they likewise procure convoys of ships of war, either to escort them to the places whither they are bound, or only a part of the way, to a certain point or latitude, beyond which they are judged out of danger of privateers, &c. FLEETING, the act of changing the situation of a tackle when the blocks are drawn together; also of changing the position of the dead-eyes, when the shrouds are become too long, which is done by shortening the shrouds and turning in the dead-eye again higher up; the use offle cordingly to replace the mechanical powers in a state- , the force by which they operated being destroyed by ing of the blocks or dead-eyes. Fleeting, therefore, isº the winding up of a watch or clock. FLESH, in Anatomy, a fibrous part of an animal body, soft and bloody, being that of which most of the other parts are composed, and by which they are connected together; or, more properly, it is that part of the body where the blood-vessels are so small as only to retain blood enough to preserve their colour red. FLES HER, in Scotland, is a butcher; and in Glasgow and some other places, there are corporations of fleshers. FLEXIBLE, is the property or quality of a body that may be bent. FLEXURE, or Flexion, is the bending of a line or figure. , FLINT. This mineral consists of 98 silica, 0:50 lime, 0.25 alumina, 0.25 oxide of iron, and 1-0 loss. Its principal use is for gun-flints, and it is also reduced to a powder, and used in the manufacture of porcelain and glass. The manufacture of gun-flints is exceedingly simple, and a good workman will make 1000 flints a day. The whole art consists in striking the stone repeatedly with a kind of mallet, and bringing off at each stroke a splinter sharp at one end, and thicker at the other. The splinters are afterwards shaped at pleasure, by laying the line at which it is wished they should break, upon a sharp instrument, and then giving it small blows with a mallet. FLOAT, a raft or quantity of timber fastened together, to be driven along a river by the tide or current. FLOAT BoARDs, those boards which are fixed to the rim, or circumference, of undershot water wheels, serving to receive the impulse of the stream, and by which means the mill is put into motion. FLOATING Bonies, are those which swim on the surface of a fluid, the stability, equilibrium, and other circumstances of which form an interesting subject of mechanical and hydro- statical investigation, particularly as applied to the construc- tion and management of ships and other vessels. The equili- brium of floating bodies is of two kinds, viz. stable or absolute, and unstable or tottering. In the one case, if the equilibrium be ever so little deranged, the bodies which compose the system only oscillate about their primitive pºsition, and the equilibrium is then said to be firm, or stable. And this stability is absolute if it takes place, whatever be the nature of the oscillations; but it is relative, if it only takes place in oscillations of a certain description. In the other state of equilibrium, if the system be ever so little deranged, all bodies deviate more and more, and the system, instead of any tendency to establish itself in its primitive position, is overset, and assumes a new position, entirely different from the former; and this is called a tottering, or unstable, equilibrium. We may form a just conception of these two states, by sup- posing an ellipse placed vertically on an horizontal plane; if the ellipse is in equilibrium on its smaller axis, it is evident that upon a slight derangement, it will tend to regain its original posi- tion, after several small oscillations, which will soon be termi- nated by the friction and resistance of the air; but if the ellipse be placed in equilibrium on its greater axis, if once it deviates from this position, it will continue to deviate more and more, till it finally turns itself on its lesser axis. In the above example, there is this remarkable circumstance; the four posi- ºly similar to F. L. O. F. L. O. 317 DICTIONARY OF MECHANICAL SCIENCE. tions of equilibrium of the ellipse, on the extremities of its two axes, are alternately stable and unstable; and this takes place in every case. For, suppose two positions of stable equilibrium to take place in any body, and such that there does not exist between them any position of the same kind, if the body be placed in one of these positions, and is made to deviate from it, and to approach the other, according as this deviation is greater or less, the body will either return to its original state, or will arrive at the other position. There will evidently, therefore, be some intermediate position, in which the body will neither tend towards one or the other of the former, but will remain at rest; but this state of equilibrium will be unstable, since, if the body be made to deviate ever so little towards one of the other positions, it will necessarily arrive at it. Hence, it appears, that if a body turning round a fixed axis passes through several positions of equilibriu will be alternately stable and unstable. The sta a floating body is the greater as its centre of gravity is an that of the displaced fluid, or as the dis- tance bet ese centres is increased; it is for this reason, that ballast is put in the lower part of vessels to prevent them from being overset. The nature of the equilibrium, as to stability, depends on the position of a certain point, called the centre of pressure; which term was first adopted by Bouguer, in in his “Traite du Navire.”—When the centre of pressure is above that of gravity, the equilibrium is stable; when it is lower than the centre of gravity, the equilibrium is tottering; when this centre coincides with the centre of gravity, the body will remain at rest wherever it is placed, without any tendency to oscillation. Laplace gives the following rule for determining whether the force which solicits the system, tends to restore it to the same state again when deranged from its primitive position, which is as follows:–If through the centre of gravity of the section of the surface of the water on which a body floats, we coin- ceive a horizontal axis to pass, such that the sum of the pro- ducts of every element of the section, multiplied by the square of its distance from this axis be less than any other horizontal axis drawn through the same centre, the equilibrium will be stable in every direction; when this sum surpasses the product of the volume of the displaced fluid, by the height of the centre of gravity of the body above the centre of gravity in this volume. This rule is principally useful in the construction of vessels which require sufficient stability to enable them to resist the effects of storms, which tend to submerge them. In a ship, the axis drawn from the stern to the prow, is that relative to which the sum above mentioned is a minimum; it is easy therefore to ascertain and measure its stability by the preceding rule. In order that a floating body may remain in equilibrio, it is also necessary that its centre of gravity be in the same vertical line with the centre of gravity of the displaced fluid, otherwise the weight of the solid will not be completely coun- teracted by the pressure of the displaced fluid. When the lower surface of a floating body is spherical or cylindrical, the centre must coincide with the centre of the figure, since the height of this point, as well as the form of the portion of the fluid dis- placed, must remain invariable in all circumstances. The place of the centre is determined by the doctrine of forces combined with the elementary principles of hydrostatics, by considering the form and extent of the surface of the displaced portion of the fluid, compared with its bulk and with the situation of its centre of gravity. If a rectangular beam be floating on its surface, the height of the centre of pressure above the centre of gravity will be to the breadth of the beam, as the breadth is to twelve times the depth of the part immersed. Hence, if the beam be square it will float securely, when either the part immersed, or the part above the surface, is less than ºn of the whole, but when it is less unequally divided by the surface of the fluid, it will overset. If however the breadth be so increased as to be nearly one-fourth greater than the depth, it will possess a certain degree of stability, whatever its density may be. See Iceberg. Floating Breakwater. This marine contrivance may con- sist of a series of square frames of timber, connected by moor- ing chains, or cables attached to anchors, or blocks of marble. The frame-work may be made of logs of Quebec yellow É. from 30 to 50 feet long, and from 18 to 20 inches square, olted together very firmly, and increased in height as the situation may be boisterous, in order to break the violence of the agitated waves, and allow the vessels riding within these quadrangular basins more safety and protection. Such break- waters are admirably adapted to bathing-places and swimming stations, since they will always produce smooth water and protect the machines. Indeed, the Editor would recommend the establishment of floating breakwater baths at bathing-places on the sea-coast. These might be so framed with reticulated fencing for their sides and bottoms, or with actual net-work, as to afford perfect safety against drowning, even to persons who could not swim. See Swimming. FLOOD, the flux of the tide, or the time the water continues rising ; called a young flood, quarter-flood, half flood, high flood. FLOOKING, among Miners, a term used to express a pecu- liarity in the load of a mine. The load, or quantity of ore, is frequently intercepted by the crossing of a different substance; in which case the load is moved to one side, and this transient part of the land is called a flooking. FLOOR or A Room, is best made of good seasoned deal, from 4 to 7 inches broad, and of as great lengths as possible, from 12 to 18 feet. Floors may be laid either ploughed or dooled; when ploughed, the feather may be worn through, and then the floor looks wretched, besides the greater quantity of nails that feathered flooring requires, render it less desirable than dooled flooring, in which there is neither groove nor feather, and but very few nails; but then this last admits the dust much more than the other. Floor, the bottom of a ship, or all that part on each side of the keel which approaches nearer to an horizontal than a per- pendicular situation, and whereon she rests when aground; thus we say, a sharp floor, a flat floor, a long floor, &c. Floor Timbers, are those parts of the ship's timbers which are placed immediately across the keel, and upon which the bottom of the ship is framed ; to these the upper parts of the timbers are ...} being only a continuation of floor-timbers upwards. FLORIN, is sometimes used for a coin, and sometimes for a money of account. The florin coin is of different values. The gold florins are most of them of a coarse alloy, some of them not exceeding thirteen or fourteen carats, and none of them seventeen and a half. As to silver florins, those of Holland are worth about 1s. 8d. FLOS, in Chemistry, the most subtile parts of bodies, sepa- rated from the more gross parts by sublimation, in a dry form. FLOTSAM, Jets AM and LAGAN, in Law. Flotsam is when a ship is sunk or cast away, and the goods float on the sea: jetsam is when a ship is in danger of being sunk, and to lighten the ship the goods are thrown overboard, and the ship notwith- standing perishes; and lagan is when the goods so cast into the sea are so heavy that they sink to the bottom, and there- fore the mariners fasten to them a buoy or cork, or such other thing that will not sink, to enable them to find them again. FLOUR MILLs, are put in motion by wind, water, steam, &c. We have before us “the Steel Corn Mill,” which, from its being portable, is of great use in armies, on shipboard, and even in private families. Externally, this mill wears the appearance given it in the annexed figure. It is said, this mill will produce flour equal in quality of fineness with the first-rate water or wind mills; and by the simple addition of a couple of ex- tra grinding plates, to shift as oc- casion may require, this mill be- comes at once a general grinding mill for grain, rice, coffee, &c. B. is a strong board, on which the work is fixed. DE, a winch to turn the mill. A, the box that covers the internal machinery. C, the hopper: and the engraving of the “Patent Portable Corn Mill,” on the Plate Mills, is a section of this machine, as you look down - upon it when the lid is removed. To regulate the mill lift, the poles out of the ratchet wheel2, then move the regulator 1 to the right, if you wish the mill set fine, viz. for grinding flour, &c.; or to the left, to set it coarser, viz. for malt, oats, beans, &c. When the mill is properly regulated, let the pole fall into one of the divisions of the ratchet wheel, by 4 M E. - | = - H= - - E 3.18 F L 0 F L 0 DICTIONARY OF MECHANICAL SCIENCE. which the plates will be kept in the position you wish. To ease the fiction of the spindle, and make the mill work easy, it is necessary to apply oil frequently to the points marked 4. If a small stone, or other hard substance, should get between the plates and check the working of the mill, it can be instantly relieved by turning the regulator to the left, by which means it will drop out. To clean the mill before using it for flour, run a few handsful of common grain through the plates two or three times, which will remove any dirt that may settle between them. Care should be taken not to set the mill too tight, as it not only makes it work hard, but wears the face of the plates unnecessarily, and in some measure destroys the vegetable quality of the wheat. There is a key to take the mill to pieces it required, or put it together, to perform which no instructions are necessary. The whole apparatus is contained in a neat iron case, mea- suring only 13inches by 8, and 10 inches deep. The movements are rendered simple and effectual, and the mill is so easy to work, that a stout boy will be able to grind as much flour in two or three hours as a family of six or eight people will consume in a week; and it is calculated, that a very few persons can grind and dress sufficient to meet the consumption of a regiment of one thousand men. The London Portable Mill Company, in Cheapside, do not claim, the merit of the original invention, but of bringing the French Military Mill to perfection, for general, public, and domestic uses, by facili- tating its operations, and by otherwise improving it to an extraordinary degree. We shall describe a flour mill of the most common sort, as follows. (See Plate, Mills.) A B is the water wheel, which is generally from eighteen to twenty-four feet, in diameter, reckoned from the uttermost edge of any float-board at A, to that of the opposite one at B. The wheel is fixed upon a very strong axis, or shaft C, one end of which rests on D, and the other on E, within the mill-house. On this shaft, or axis, and within the mill-house, is a wheel F, about 8 or 9 feet in diameter, having cogs all round, which work in the upright staves, or rounds of a trundle G. This trundle is fixed upon a strong iron axis, called the spindle, the lower end of which turns in a brass foot, fixed at H, in a horizontal beam H. M., called the bridge-tree; and the upper and of the spindle turns in a wooden bush fixed into the nether millstone, which lies upon beams in the floor I. The top of the spindle above the bush is square, and goes into a square hole in a strong iron cross, called the rynd ; under which, and close to the bush, is a round piece of thick leather upon the spindle, which it turns round at the same time as it does the rynd. The rynd is let into grooves in the under surface of the running millstone K, and so turns it round in the same time that the trundle G is turned round by the cog-wheel F. This stone has a large hole quite through its middle, called the eye of the stone, through which the middle part of the rynd and upper end of the spindle may be seen, whilst the four ends of the rynd lie below the stone in their grooves. One end of the bridge-tree which sup- ports the spindle, rests upon the wall, whilst the other is let into a beam, called the brayer, L. M. The brayer rests in a mortise at L, and the other end M, hangs by a strong iron rod N, which goes through the floor I, and has a screw-nut on its top at 0; by the turning of which nut, the end M of the brayer is raised or depressed at pleasure, and consequently the bridge- tree and the upper millstone. By this means, the upper mill- stone may be set as close to the under one, or raised as high from it, as is convenient. The corn will be ground fine or coarse, according to the distance of the millstones from each other. On the top of the box which encloses the millstone, stands a frame for holding the hopper P, to which is hung the shoe Q, by two lines fastened to the hinder part of it, fixed upon hooks in the hopper, and by one end of the string R fastened to the fore part of it, the other end being twisted round the pin S. As the pin is turned one way, the string draws up the shoe closer to the hop- per, and so lessens the aperture between them; and as the pin is turned the other way it lets down the shoe, and enlarges the aperture. If the shoe be drawn up quite to the hopper, no corn can fall from the hopper into the mill; if it be let down a little, some will fall; and the quantity will be more or less, according as the shoe is more or less let down; for the hopper is open at bottom, and there is a hole in the bottom of the shoe, not directly under the bottom of the hopper, but nearer the lowest end of the shoe, over the middle eye of the millstone. There is a square hole in the top of the spindle, in which is put the feeder F; this feeder, as the spindle turns round, jogs the shoe three times in each revolution, and so causes the corn to run con- stantly down from the hopper through the shoe into the eye of the millstone, where it falls upon the top of the rynd, and is, by the motion of the rynd, and the leather under it, thrown below the upper stone, and ground between it and the lower one. The violent motion of the stone creates a centrifugal force in the corn going round with it, by which means it gets farther and farther from the centre, as in a spiral, in every revolution, until it be quite thrown out; and being then ground, it falls through a spout, called the mill-eye, in trough. When too much corn is let into the mill, the mill is fed too fast, the corn bears up the stone, round too coarse; and besides, it clogs the mill, so as tº make it go too slow. When the mill is too slowly fed it goes too fast, and the stones, by their attrition, are apt to strike fire. Both which inconveniences are avoided by turning the pin S backward or forward, which draws up or lets down the shoe, and thus regu- lates the feeding, as is found convenient; the greater the quantity of water that falls upon the wheel, and the heavier the running millstone is, the faster will the mill bear to be fed, and consequently it will grind the more. And on the contrary, the lighter the stone, and the less the quantity of water, so much slower must the feeding be. But when the stone is considerably worn, and become light, the mill must be fed slowly at any rate; otherwise the stone will be too much borne up by the corn under it, which will make the meal coarse. The power sufficient to turn a heavy millstone, is but very little more than what is necessary to turn a light one; for as it is supported upon the spindle by the bridge-tree, and the end of the spindle that turns in the brass foot therein being but small, the differ- ence arising from the weight is but very inconsiderable in its action against the power or force of the water. It is natural the corn should be crushed when it comes to a place where the interval between the two millstones is less than its thickness, yet the upper millstone being supported on a point which it can never quit, it does not so clearly appear why it should produce a greater effect when it is heavy, than when it is light; since, if it were equally distant from the nether millstone, it could only be capable of a limited impres- sion: but as experience proves that this is really the case, it is necessary to discover the cause. The spindle of the millstone being supported by a horizontal piece of timber, about nine or ten feet long, resting only on both its ends, by the elasticity of this piece, the upper millstone is allowed a vertical motion, playing up and down; by which movement, the heavier the stones are, the more strongly is the corn pressed between them. Both the upper and under millstones have channels cut into them, (see figs. 1 & 2, page 319,) obliquely from the centre to the circumference, in order to cut and grind the corn. These furrows are cut perpendicularly on one side, and obliquely on the other, which gives each furrow a sharp edge; and in the two stones they come, as it were, against one another, like the edges of a pair of scissars, and so cut the corn to make it grind the easier, when it falls upon the places between the furrows. These are cut the same way in both stones, when they lie upon their backs, which makes them run crossways to each other when the upper stone is inverted, by turning its furrowed surface towards that of the lower; for if the furrows of both stones lay the same way, a great deal of the corn would be driven onward in the lower furrows, and so come out from between the stones, without being cut or bruised. Also the grinding surface of the under stone is a little convex from the edge to the centre, and that of the upper stone a little concave, so that they are farthest from one another in the middle, and approaching gradually nearer towards the edges. By this means the corn, at its first entrance between the stones, is only bruised; but as it goes farther on towards the circumference or edge, it is cut smaller and smaller, and at last finely ground, just before it comes out from between them. When the fur- rows become blunt or shallow by wearing, the running stone F L o F L 0 DICTIONARY OF MECHANICAL SCIENCE. 319 must be taken up, and both stones new drest with chisel and hammer; and every time the stone is taken up, there must be some tallow put round the spindle upon the bush, which will soon be melted by the heat the spindle acquires from its turn- ing and rubbing against the bush, and so will get in betwixt them, otherwise the bush would take fire very soon. The bush must embrace the spindle quite close, to prevent any shake in the motion, which would make some parts of the stones grate and fire against each other, whilst the other parts of them would be too far asunder, and by that means spoil the meal. Whenever the spindle wears the bush, so as to begin to shake in it, the stone must be taken up, and a chisel driven into several parts of the bush; and when it is taken out, wooden wedges must be forced into the holes, by which means the bush will be made to embrace the spindle again, close all round. In daim wedges into bush on opposite sides of the spindle, other- wise it willºb own out of the perpendicular, and so hinder the upper stone"from being set parallel to the under one, which is absolutely necessary for making good work. When any accident of this kind happens, the perpendicular position of the spindle must be restored by adjusting the bridge-tree with proper wedges between the brayer and it. - It frequently occurs, that the rynd is a little wrenched in laying down the upper stone upon it, or is made to sink a little lower on one side of the spindle than on the other, and this will cause one edge of the upper stone to drag all round upon the other, while the opposite edge will not touch. But this is easily set to rights, by raising the stone a little with a lever, and putting bits of paper, cards, or thin chips, between the rynd and the stone. A less quantity of water will turn an overshot mill (where the wheel has buckets instead of float-boards) than a breast- mill, where the fall of water seldom exceeds half the height of the wheel ; so that where there is but a small quantity of water, and a fall great enough for the wheel to lie under it, the bucket, or overshot wheel, is always used; but where there is a large body of water with a little fall, the breast, or float-board wheel, must be used. Where the water runs only upon a small decli- vity, it can act but slowly upon the under part of the wheel; in which case, the motion of the wheel will be slow, and there- fore the floats ought to be very long, though not high, that a large body of water may act upon them, so that what is want- ing in velocity may be made up in power; and then the cog- wheel may have a greater number of cogs, in proportion to the rounds in the trundle, in order to give the millstone a suſlicient degree of velocity. It was the opinion of Smeaton, that the powers necessary to produce the same effect on an undershot wheel, a breast- wheel, and an overshot wheel, must be to each other as the numbers 24, 1775, and 1. For the float-board of a river mill is impelled, not by the velocity of the stream, but only by the ex- cess of this above the velocity of the board itself. In the under- shot wheel a great loss of power is occasioned by the accumu- lation of dead water, or of the water which having impinged against the float-board, remains nearly stagnant, and therefore impedes the advance of the next float-board. - In the Plate of Mills, we have given a section of a DOUBLE FLOUR MILL, of which A A is the water wheel; BB the shaft or axle; C C a wheel fixed upon the same axle, contain- ing 90 teeth, or cogs, to drive the pinion; No. 1 having 23 teeth, which is fastened upon the vertical shaft D. No. 2, a wheel fixed upon the shaft D, containing 82 teeth, to turn the two pinions F, F, having 15 teeth, which are fastened upon the iron axles or spindles that carry the two upper milistones. E E, the beam or sill that supports the frame on which the under millstones are laid. GG, the cases or boxes that enclose the upper millstones; they should be about two inches distant from the stone all round its circumference. TT, the bearers, called bridges, upon which the under end of the iron spindles turn. These spindles pass upward through a hole in the middle of the nether millstones, in which is fixed a wooden bush...that their upper ends turn in. The top part of the spindles above each wooden bush, is made square, and goes into a square hole in an iron cross, which is admitted into grooves in the middle and under surface of the upper mill- ig this, great care must be taken to drive equal | stone. By this means that stone is carried round along with the trundles FF, when turned by the wheel No. 2. ‘ One end of the bridges TT, is put into mortises in fixed bearers, and the other end into mortises in the bearers that move at one end on iron bolts, their other ends hanging by iron rods having screwed nuts, as U U, so that when turned forward or back- ward, they raise or depress the upper millstones, according as the miller finds it necessary. SS, the feeders, in the under end of each of which is a square socket that goes upon the square of the spindles above the iron cross or rynd, and having three or four branches that move the spout or shoe, and feed the wheat constantly from the hoppers into the hole or eye of the upper millstone, where it is introduced betwixt the stones, and by the circular motion of the upper stone acquires a centri- fugal force; and proceeding gradually from the eye of the mill- stone towards the circumference, is at length thrown out in flour or meal. R. R, the sluice, machine, and handle, to raise the sluice, and let the water on the wheel A to drive it round. No. 3 is a wheel fixed upon the shaft D, containing 44 teeth, to turn the pinion No. 4, having 15 teeth, which is fastened upon the horizontal axle H. On this axle is also fixed the barrel K, on which go the two leather belts that turn the wire engine and bolting mill. L, an iron spindle, in the under end of which is a square socket that takes in a square on the top of the gudgeon of the vertical shaft D. There is a pinion M, of 9 teeth, fixed on the upper end of the spindle L, to turn the wheel M. M., having 48 teeth, which is fastened upon the axle round which the rope Z Z rolls, to carry the sacks of flour up to the cooling benches. By pulling the cord O O a little, the wheel M M and its axle are put into motion, in consequence of that wheel and its axle being moved horizontally, until the teeth of the wheel are brought into contact with those of the pinion at the top of the spindle L; and on the contrary, by pulling the cord PP, the wheel M and its axle are moved in the opposite horizontal direction, till they are thrown out of geer with the pinion, and the rotatory motion of that wheel stops. But when the sack of flour is raised up to the lever Q, it pushes up that end of the lever, and of course the other end down ; by which means the pinion M is disengaged, and thus that part of the machine stops of itself. N N are two large hoppers, into which the clean wheat is put to be conveyed down to the hoppers SS, placed on the frame immediately above the millstones. W W, the side wall of the millhouse. V, the couples or frame of the roof. XX, windows to lighten the house. UNDER-Millstone.—Fig. 1. Fig. 1, is a correct repre- = sentation of the surface of =ºffiºe. the undergrinding millstone;  º |||| Nº. the way of laying out the AFAºi #2, #, roads or channels; the wood- AExºshiſhº en bush fixed into the hole # = É #º in its middle, in which the *~ 3 - #Pºººººº. upper end of the iron spindle #. §º bº | = == turns round ; and the case É º or hoops that surround the E ºº: º º,” =º e **ś Ø H upper one, which ought to be two inches clear of the stone *- | *.* &#|| 'F' all round its circumference. *NHHHH Fig. 2, is the upper grinding millstone, with an iron cross or rynd in its middle ; in the centre of which is a square hose that takes in a square on the top of the iron spin- dle, to carry round the mill- stone. When the working sides or faces of the mill- stones are laid uppermost, the roads (or channels) must lie in the same direction in , both ; so that when the up- per stone is turned over, and its surface laid upon the under one, then the channels may cross each other, which assists ingrinding and throw- Y= T-_ 820 F L 0 F. L. O. Diction ARY of MECHANICAL scIENCE ing out the flour; the sharp edges of the two furrows then cut- ting against each other like scissors. The roads are likewise laid out according to the way the upper stone revolves. In those represented in the figures the running millstone is sup- posed to turn “sun-way,” or as in what is called a right-handed mill; but if the stone revolves the other way, the channels must be reversed, and then the mill is termed a left-handed one. When the diameter of the upper stone is about 6 feet, as is generally the case, the lower is about an inch more; the upper stone then contains about 22} cubic feet, and weighs rather more than 19,000 pounds. A stone of this kind ought never to revolve more than 60 or 70 times in a minute; for a more rapid motion would heat the meal. Nor must the water wheel be too large, for in that case its angular motion will be too slow ; on the contrary, if the wheel be too small, it will be deficient in moving power; 18 feet diameter is recommended as a proper medium. Ferguson, on the supposition that the floats of the wheel ought to move with a third part of the Velocity of the water—a supposition, however, not strictly con- sistenteither with theory, or with Smeaton's experiments—gives the following rules for constructing the chief parts of the mill. 1. Measure the perpendicular height of the fall of water in feet above that part of the wheel on which the water begins to act, and call that the height of the fall. 2. Multiply this con- stant number 64:2882 (or rather 64) by the height of the fall in feet, and extract the square root of the product, which will be the velocity of the water at the bottom of the fail, or the num- ber of feet the water moves per second. 3. Divide the Velocity of the water by 3, and the quotient will be the Velocity of the floats of the wheel in feet per second. 4. Divide the circumference of the wheel in feet, by the velocity of its floats, and the quotient will be the number of seconds | in one turn or revolution of the great water wheel, on the axis of which is fixed the cog wheel that turns the trundle, 5. Divide 60 by the number of seconds in one turn of the water wheel or cog-wheel, and the quotient will be the number of turns of either of these wheels in a minute. 6. Divide 60 (the number of turns the millstone ought to have in a minute) by the abovesaid number of turns, and the quotient will be the number of turns the millstone ought to have for one turn of the water or cog wheel. e Then, 7. As the required number of turns of the millstone in a minute is to the number of turns of the cog wheel in a minute, so must the number of cogs in the Wheel be to the number of staves or rounds in the trundie on the axis of the millstone, in the nearest whole number that can be found.—By these rules the following table is calculated, in which the diameter of the water wheel is supposed 18 feet, and consequently its circumference 564. THE MILLwRIGHT’s TABLE. Number P Veloci Vel *:::::: *::::: %;ſ Number o #|º]º lºſº;|### #####|##|*|†;|T|º, ſº water. second. second. | minute. 0 § § these cogs! and states. the wheel. 3 # º States. l _8-02 2-67 2-83 21-20 |127 6 24-17 59-91 2 11:40 3.78 4-00 || 15-00 || 105 7 || 15-00 60-00 3 13.89 4-63 4.91 || 12-22 || 98 8 12-25 60-14 4 16-04 5-35 5'67 10:58 95 9 || 10.56 59.87 5 17-93 5-98 6-34 9°46 | 85 9 9-44 59-84 6 19-64 6-55 6-94 8-64 78 9 8.66 60.10 7 21-21 7-07 7-50 8-00 || 72 9 8.00 60-00 8 22-68 7.56 8-02 7-48 || 67 9 7.44 59.67 9 24-05 8-02 8-5 l 7:05 || 70 10 || 7-00 59-57 10 25-35 8-45 8-97 6-69 67 10 6-70 60-09 11 26-59 8-86 9-40 6-38 64 10 3.40 60-16 12 27.77 9°26 9-82 6-1 l 61 10 6-10 59-90 13 28-91 9-64 || 10-22 5-87 59 10 5-80 60.18 14 30-00 || 10-00 || 10-60 5-66 56 10 5-60 59-36 15 31 -05 || 10-35 10-49 5°46 || 55 10 5-40 60-48 16 32-07 || 10-69 || 11:34 5-29 53 10 || 5.30 60.10 17 || 33-06 11:02 || 11.70 5-13 || 51 10 5-10 59-67 18 34.02 || 11-34 12-02 4.99 || 50 I0 5.00 60. 10 19 34.95 || 11.65 | 12:37 4-85 49 10 4-80 60-61 * 20 || 35-86 || 11.92 || 12.68 4.73 || 47 10 4-70 59°59 l Fenwick’s experiments on some of the best mills for grind- ing corn, were undertaken to form the following tables, illus- trative of the effect of a given quantity of water, in a given time, applied to an overshot water wheel of a given size. . The millstones were from 43 to 5 feet diameter, and made from 90 to 100 revolutions per minute. And the result was, that the power requisite to raise a weight of 300 lbs. avoirdupoise, with a velocity of 190 feet a minute, would grind one boll of good rye in an hour; but to avoid imperfections, it is taken, for prac- tice, at 300 lbs. raised with a velocity of 210 feet per minute (being one-tenth more); and for grinding 2, 3, 4, or 5, bolls of rye per hour, requires a power = 300 lbs. raised with the velocity of 350, 506, 677, or 865 feet a minute respectively. The difference of the power requisite to grind equal quanti- ties of wheat from that for rye, is very trifling. The boll is four bushels Winchester measure ; two bolls aſſºherefore one quarter. The power necessary to raise a y º ºſt of 300 lbs. avoirdupoise, with a velocity of 390 feet periºute, will pro- perly prepare one ton of old rope per week, for the purpose of making paper; and for grinding down in like manner two tons of the same material in a week, we should want a power able to raise 300 lbs. with a velocity of 525 feet in a minute, to work the mill 12 hours daily. TABles, shewing the Quantity of Water (Ale Measure) requisite to grind different quantities of Corn, from 1 to 5 Bolls (Win- chester Measure) per hour, applied to overshot Water-Wheels, from 10 to 32 feet diameter; also the size of the Cylinder of the common Steam-Engine to do the same work. The water-wheel 10 feet diam. || The water-wheel, 16 feet diam- Diam. in in- || Quantity of Diam. º in- Quantity of ches of the uantity of ches of the Bolls of water ºi. cylinder of a * water requi-|cylinder of a º site, in ale steam-engine || g.º.d site: in ale |steam-engine groun gallons, to do the . hour gallons, to do the . per hour. per minute. same work. p "| per minute, same work.' I 786 12'5 I * 491 12:5 1} 1056 14.6 1} . 650 ; 2 1341 16.75 2 811 6-75 2} 1617 T8'5 2} 993 18'5 3 1894 20°2 3 1176 20-2 3# 2220 21-75 - 3# 1380 : 4 2541 23-25 4 1582 3. 4} 2891 24-75 4; 1802 24-75 5 3242 26.25 5 2023 26°25 The water-wheel, 12 feet diam. The water-wheel, 18 feet diam. Water, gal- e . Water, e te B. P*| lons p : º: 1I] B. per gallons per º: II? OUITs minute. lil Cºles, OUllſ, minute. 1D Cºle Ss I 655 12:5 1 440 12°5 1} 873 14'6 1} 595 14°6 2 1091 16.75 2 730 16.75 2} 1343 18°5 2} 860 18°5 3 1576 20°2 3 1054 20-2 3% 1840 21.75 3# 1227 21-75 4 2117 23-25 4 1400 23-25 4} 2408 24-75 4} 1600 24-75 5 2700 26.25 5 1800 26.25 The water-wheel, 14 feet diam. ||The water-wheel, 20 feet diam. Bº per º: Cylinder, in ||Bolls per º, Cylinder, in OUlfe * > inches. hour. & inches. minute. minute. l 564 12'5 I 392 12:5 1% 740 14°6 1; 530 14'6 2 927 16.75 2 675 16.75 2% 1140 18'5 2% 808 18'5 3 1353 2012 3 945 2012 3# 1583 21 “V5 3# 1110 21.75 4 1811 23-25 ... 4 1270 23:25 4} 2060 24-75 4} 1445 24-75 5 2306 26°25 5 1623 26:25 F L O , E) ICTIONARY OF MECHANICAL SCIENCE. The water-wheel, 22 feet diam. ||The water-wheel, 28 feet diam. Water * - º - Water, i., . . . . . . Bolls per t "... Cylinder, in || Bolls per| * ... Cylinder, in . f .." gallons per y inches. "..." i gallons per *. . . miinute. , . minute. . . . . . 1 350 T2°5 1. 282 12:5 ; , 1} . . . . 473. 14.6 1} : 370 14.6 2 - 594 1675 2 . . . . 463 16.75 2}. 722 18°5 2} | . 570 18°5 . 3 860 20:2 3. 676 20:2 . 3} 1007 || 21.75 3} 791 21.75 4 * 1153 23°25 4 905 23:25 4} . 1313 24.75 4} 1030 24-75 5 1472 26°25 5 1153 26°25 The water-wheel, 24 feet diam. ||The water-wheel, 30 feet diam. Water, Bolls per ...º.º. Cylinder, in || Bolls per Cylinder, in hour. * - inches. º *er '. I 327 12.5 l 267 12.5 1} 436 14'6 l; 355 | 4°6 2 545 16.75 2 447 16.75 2} . 671 18.5 2} 545 185 3 . 788 2012 3 645 20°2 3} 920 21.75 3% 750 21°75 4 1055 23'25 4 . . 858. 23'25 4} 1204 24-75 4% 983 24*75 5 1350 26.25 5. 1 106 26.25 The water-wheel, 26 feet diam. ||The water wheel, 32 feet diam, Water ſº & Water * * * g : Bolls per * ... Cylinder, in || Bolls per ‘.... Cylinder, in - º gallons per '. º gallons per y inches. minute. minute. 1 303 12:5 I 245 12:5 1} 403 14.6 1% 325 14'6 2 504 . 1675 2 406 16.75 2} 617 18°5 2} 496 18°5 3 , 730 20:2 3 588 20:2 3% 852 21°75 3% 690 21.75 4 975 23-25 4 791 23-25 4% Il 11 24-75 4; 900 24-75 5 1247 26'25 . 5 1012 26.25 A Rule to make the foregoing Table applicable to Mills intended to be turned by undershot or breast Water-wheels.-The power required on an undershot water-wheel, to produce an effect equal to that of an overshot, (to which the tables are applicable,) is as 2.4 to 1; and also the power required on a breast water- ..wheel, which receives the water on some point of its circum- ference, and afterwards descends on the ladle boards, to pro- duce an equal effect with an overshot water-whecl, is as 1.75 10 l. TABLE, shewing the necessary Size of the Cylinder of a common Steam-Engine to grind different quantities of Corn, from 1 to 12 Bolls (4 to 48 Bushels, Winchester Measure) per hour. Bolls of Corn Bolls of Corn ind Diagº the d Diameter of the pää. in #s. p; ". 1.*}. - 1 . . . . . . . . . . . . . . 12.3 7 . . . . . . . . . . . . . .29'8 # . . . . . . . . . . . . . . 14-6 7%. . . . . . . . . . . . . . 31-1 2 . . . . . . . tº e s e º a º 16.75 8 . . . . . . . . . . . . . . 32 2} . . . . . . . . . . . . . . 18'5 8% . . . . . . . . . . . . . . 33-3 3 . . . . . . . . . . . . . . 20:2 9 . . . . . . . . . . . . . . 34-2 3}. . . . . . . . . . . . . . 21.75 9%. . . . . . . . . . . . . . 35°2 4 . . . . . . . . . . . . . . 23'25 10 . . . . . . . . . . . . . .36 4} . . . . . . . . . . . . . . 24-75 10%. . . . . . . . . . . . . . .37°3 5 . . . . . . . . . . . . . . 26.25 ll . . . . . . tº e º a tº e º e 38 5% . . . . . . . . . . . . . .27:25 11% . . . . . . . . . . . . . . 38'85 6 . . . . . . . . e tº e º tº e 28, 1 12 . . . . . . . . . . . . . . 39'5 6}. . . . . . . . . . . . . . 29 N. B. This table will be applicable to any improved steam-engine, as well as that of the common kind, if the ratio of their efficacies is known. 1 * The Application of the foregoing Tables. Example 1. If a stream of water, producing 808 gallons, ale measure, per minute, can be applied on an overshot water-wheel 20 feet | diameter, what quantity of corn will it be able to grind per | hour?—Look in the tables under a 20 feet water-wheel, and | opposite 808 h gallons will be found 2% bolls of corn ground per Ollſ, . . . . . x - . - 2. If a stream of water, producing 808 gallons, ale measure, per minute, can be applied to an undershot water-wheel 20 feet diameter, what quantity of corn can it grind per hour?—It is found by the tables, that if applied on an overshot water- wheel 20 feet diameter, the stream will grind 2% bolls per hour; and from the rule preceding the last table, the power required by the undershot to that of the overshot water-wheel, to pro- duce an equal eſſect, being as 2.4 to 1, therefore, as 2.4 : 1 : : 25 : 1:04 bolls of corn ground per hour by means of the stream. 3. If a stream of water, producing 808 gallons, ale measure, per minute, can be applied on a breast water-wheel 20 feet diameter, what quantity of corn can it grind per hour !—It is found by the tables, that if applied on an overshot water wheel of equal size, 2% bolls of corn will be ground per hour; and from the rule above, the power of a breast water-wheel to that of an overshot water-wheel, to produce an equal effect, is as 175 to 1, therefore, as 1.75 : 1 : : 2,5 : 1'42 bolls of corn ground per hour by the stream. . . . . * 4. Of what diameter must the cylinder of a common steam- engine be made, to grind 10 bolls of corn per hour !—By look- ing in the foregoing table, opposite 10 bolls ground per hour, the diameter of the steam cylinder will be found to be 86inches. FLOWER, Flos, the most beautiful part of trees and plants, containing the organs or parts of fructification. The method of preserving flowers in their natural beauty has been much sought after. The following method does well :—Gather the flowers when they are not thoroughly open, in the middle of a dry day, put them into a glazed earthen vessel; fill this to the top with them, and when full, sprinkle them over with some French wine, with a little salt in it; then set them by in a cellar, tying down the mouth of the pot. After this they may be taken out at pleasure; and on setting them in the sun, or within the reach of the fire, they will open as if growing natu- rally ; and not only the colour, but the odour also, will be preserved. Most persons can try and verify this experiment. Flow ER De Lls, or Flower de Luce, in Heraldry, a bearing representing the lily, called the queen of ſlowers, and the true hieroglyphic of majesty. - - - FLOWING, the position of the sheets or lower corners of the principal sails when they are loosened to the wind, so as to receive its more nearly perpendicular than when they are close hauled, although more obliquely than when going before the wind; a ship is therefore said to have a flowing sheet, when the wind crosses the line of her course nearly at right angles, that is to say, a ship steering due north with the wind at the east, or directly on her side, will have a flowing sheet; whereas if the sheets were extended close aft, she would sail two points nearer the wind, viz. N. N. E. - FLUATS, in Chemistry, salts first discovered by Scheele, and distinguished by the following properties. When sulphu- ric acid is poured upon them they emit acrid vapours of fluoric acid, which corrode glass. When heated, several of them phosphoresce. They are not decomposed by heat, nor altered by combustibles. They combine with silica by means of heat. Most of them are sparingly soluble in water. - FLUENT, in Fluxions, the flowing quantity, or that which is continually increasing or decreasing. - FLUID, or FLUID BoDY, is that whose parts yield to the smallest force impressed upon them, and which by yielding are easily moved amongst each other; in this sense a fluid stands opposed to a solid, whose parts do not yield, but constantly maintain the same relative situation. The fluidity of bodies is accounted for by supposing them made up of infinitely small particles, possessing, with regard to each other, an attrac- tive and, repulsive power, which being equal, places the whole system in equilibrium, whereby it obeys any external force impressed upon it. This hypothesis evidently places the seve- ral particles of a fluid at small distances from each other, and consequently supposes them to be porous, or to possess certain 34. 322 F. L. U F L U. DICTIONARY OF MECHANICAL SCIENCE. vacuities, the existence of which may be demonstrated from various experiments. Thus, water will dissolve a certain quan- tity of salt; after which it will absorb a little sugar, and after that a little alum; and all this without increasing its bulk: which evidently shews, that the particles of these solids are so far separated as to become smaller than the vacuities, or interstices, between the particles of the fluid or water. FIuids are divided into Elastic and Non-elastic. FLUIDs, are those which may be compressed into a smaller compass, but which, on removing the pressure, resume again their former dinnensions; as air, and the various gases. Non- elastic FLUIDs, are those which occupy the same bulk under all pressures, or, if they be at all compressible, it is in a very triſling degree; such as water and other liquids. FLUOR. This spar may be divided into three species, com- pact, foliated, and earthy. The second species is most abun- dant, and is usually called in England, Derbyshire spar. Berzelius found its constituents to be 72°1 lime, and 27.9 fluoric acid. It is cut into a variety of ornamental forms. When two pieces are rubbed together in the dark, they phos- phoresce with a blue and green light. Sulphuric acid evolves flouric fumes which corrode glass. FLUORIC Acid, is found in combination with calcareous carth, in Derbyshire spar. If the pure spar be placed in a retort of lead or silver, with a receiver of the same metal adapted, and its weight of sulphuric acid be then poured upon it, the fluoric acid will be disengaged with a moderate heat. This acid readidly combines with water, for which purpose it is necessary that the receiver should be previously half filled with that fluid. This acid attacks glass, and corrodes it; and it has been employed in etching figures on glass: the whole glass must be covered with a thin coating of wax, in which the figure is to be traced, so as to leave bare the parts intended to be acted upon. This acid consists of oxygen, and its base fluor. FLUIORINE, in Chemistry, a substance that has never yet been detected in an uncombined state. There is reason, how- ever, to believe it is an elementary substance. With hydrogen it ºrms fluoric acid. Combined with fluor it forms the fluoric a C101. FLURRY, a light breeze of wind shifting to different places, and causing a little rufiling on the calm surface of the sea. FLUTE, FISTULA, wind, an instrument of music. The tones or notes are changed by stopping and opening the holes dis- posed for that purpose along its side. The ancient fistulae, or flutes, were inade of reeds, afterwards of wood, and last of metal. Flutes are now sometimes made of glass. FLUTE, German, is an instrument different from the common flute ; instead of being put into the mouth to be played, the end is stopt with a plug, and the lower lip is applied to a hole about two inches and a half, or three inches, distant from the end. It is perforated with holes, the lowest of which is stopped and opened by the little finger's pressing on a brass or silver key. FLUTEs, or Flutings, in Architecture, perpendicular channels, or cavities, cut along the shaft of a column or pilaster. FLUX, in Metallurgy, is sometimes used synonymously with fusion; for instance, an ore, or rather matter, is said be in liquid flux when it is completely fused. But the word flux is generally used to signify certain saline matters, which facilitate the fusion of ores, and other substances which are not easily fusible in assays, and in the reduction of ores. In the large way, limestone and fusible spar are used as fluxes. The fluxes used in assays, or philosophical experiments, consist usually of alkalies, which render the earthy mixtures fusible, by convert- ing them into glass; or else glass itself in powder. Alkaline fluxes are either the crude flux, the white flux, or the black flux. Crude flux is a mixture of nitre and tartar, which are put into the crucible with the mineral intended to be fused. The detonation of the nitre with the inflammable matter of the tar- tar, is of service in some operations; though generally it is attended with inconvenience on account of the swelling of the materials, which may throw them out of the vessel, if proper care be not taken either to supply only a little of the mixture at a time, or to procure a large vessel. White flux is formed by projecting equal parts of a mixture of nitre and tartar, by moderate portions at a time, into an ignited crucible. In the detonation which ensues, the nitric acid is decomposed, and Elastic flies off with the tartaric acid, and the remainder consists of the potash in a state of considerable purity. This has been called fixed nitre. Black flux differs from the preceding, in the proportion of its ingredients. In this the weight of the tartar is double that of the nitre ; on which account the com- bustion is incomplete, and a considerable portion of the tartaric acid is decomposed by the mere heat, and leaves a quantity of coal behind, on which the black colour depends. It is used where it is intended to reduce metallic ores, and effects it by uniting with the oxygen of the oxide. - . . FLUx, in Medicine, an extraordinary issue, or evacuation, of some humours of the body. FLUXION, in the Newtonian Analysis, denotes the velocity with which a flowing quantity increases by its generative motion, by which it stands contradistinguished from a fluent, or flowing quantity, which is constantly and indefinitely increas- ing, after the manner that a surface is described by the motion of a line, or a solid by the motion of a surface. Or a fluxion may be otherwise defined, as the magnitude by which any flowing quantity would be uniformly increased in a given por- tion of time, with the generating celerity at any proposed position or instant, supposing it thence to continue invariable. Fluzional Analysis, is the algorithm, or analysis of fluxions and flowing quantities, distinguishable from the differential calculus both by its metaphysics and notation, but in all other respects the two methods are identical. The invention of the fluxional analysis does more honour to: the powers of the human mind, than perhaps any discovery of this or any preceding age ; it opens to us a new world, and extends our knowledge as it were to infinity; it carries us beyond those bounds which seem prescribed to our mental powers, and leads to investigations and results which must other- wise have for ever remained in impenetrable obscurity. And without entering into all the proofs we could adduce in support of our assertion, we ascribe the glory of this invention to Sir Isaac Newton, though it has been also claimed on the continent for Leibnitz. But as we do not intend to enter upon this subject here, the reader will not expect a minute detail of the principle of fluxions. It will be sufficient to observe, that all finite magnitudes are here conceived to be resolved into infi- nitely small ones, supposed to be generated by motion, as a line by the motion of a point, a superficies by a line, and a solid by a superficies; of which they are the elements, moments, or differences. The art of finding these infinitely small quanti- ties, or the velocities by which they are generated, and of working on them, and discovering other infinite quantities by their means, makes what is called the Direct Method of Fluations. And the method of finding the fluents or flowing quantities, these fluxions being given, is what constitutes the Inverse Method. What renders the knowledge of infinitely small quantities of such great use and extent is, that they have relations to each other, which the finite magnitudes, whereof they are the infi- nitesimals, have not. Thus for example, in a curve of any kind whatever, the infinitely small differences of the ordinate and absciss have the ratio to each other, not of the ordinate and absciss, but of the ordinate and subtangent; and of con- sequence, the absciss and ordinate being known, will give the subtangent; or, which amounts to the same, the tangent itself. . Notation.—The method of notation in fluxions, introduced by the inventor, Sir Isaac Newton, is as follows:—The variable, or ſlowing quantity, to be uniformly augmented, as suppose the absciss of a curve, he denotes by the final letters v, a, y, z; and their fluxions by the same letters with dots placed over them, thus, v, r, j, 3. And the initial letters, a, b, c, d, &c. are used to express invariable quantities. Again, if the fluxions themselves are also variable quantities, and are continually increasing or decreasing, he considers the velocities with which they increase or decrease, as the fluxions of the former fluxions or second fluxions, which are denoted by two dots over them, thus, y a 2. After the same manner, one may consider the increase and diminution of these, as their fluxions also, and thus proceed to the third, fourth, &c. fluxions, which will be denoted thus, F O C F O L DICTIONARY OF MECHANICAL SCIENCE. - sº ºn - * gº * y & 2 : y º ż. Lastly, if the flowing quantity be a surd, as Va: — y, he denotes its fluxion by (Va.- y)"; if a fraction #; it is denoted by (# 3/ fluxions of compound quantities are expressed by placing the Letter F, or f before them, thus, instead of (V(a. — y) )', is written F. V (a — y) or f. V (a.— y). We shall, however, in the following article, denote the fluxion by F, and the fluent by f.; so that, Sometimes, however, the F. V (a — y) Rdenote the V (a — y) F. a. -- a a." - --> # ac + a ac” TST 2 T $fiuxions o: b -- a. f. a. V (r + a wº) denote the W* V (x + a zº) f. . . . . a b fluents of —**— . a + a wº . a + a rº FLY, is a name given to a certain appendage to many machines, either as a regulator of their motions, or as a collector of power. When used as a regulator, the fly is commonly a heavy disk or hoop balanced on its axis of motion, and at right angles to it; though sometimes a regulating fly consists of vanes or wings, which, as they are whirled round, meet with considerable resistance from the air, and thus soon prevent any acceleration in the motion ; but this kind of regulator should rarely, if ever, be introduced in a working machine, as it wastes much of the moving force. When the fly is used as a collector of power, it is frequently seen in the form of heavy knobs at the opposite ends of the straight bar, as in the coin- ing press. - FLY of an Ensign, Pendant, &c. the breadth or extent from the staff to the extreme edge or end that flutters loose in the wind. - FLY Boat, or Flight, a large flat-bottomed Dutch vessel, whose burden is generally from 4 to 600 tons: it is distinguished by a stern remarkably high, and by very broad buttocks below. FLYERS, in Architecture, such stairs as go straight, and do not wind round, or have the steps made tapering ; but the fore and back part of each stair, and the ends respectively parallel to one another, as in the annexed figure. So that if one flight do not carry you to your designed height, there is a broad half space; and then you fly again, with steps as before, every where of the same breadth and length as in the diagram. FLYING PINIon, is part of a clock, having a ſly, to gather air, and restrain the rapidity of the clock’s motion. FLYING, the progressive motion of a bird, or other winged animal, in the liquid air. The parts of birds chiefly concerned in flying, are the wings, by which they are sustained or wafted along. The manner of flying is thus:—The bird first bends his legs, and springs with a violent leap from the ground, then opens and expands the joints of its wings, so as to make a right line perpendicular to the sides of his body; thus the wings, with all the feathers therein, constitute one continued lamina. Being now raised a little above the horizon, and vibrating the wings with great force and velocity perpendicu- larly against the subject air, that ſluid resists those succussions, both from its natural inactivity and elasticity, by means of which the whole body of the bird is protruded. The resistance the air makes to the withdrawing of the wings, and conse- quently the progress of the bird, will be so much the greater, as the waft or stroke of the fan of the wing is longer. FOCUS, in Optics, is a point wherein several rays concur, or are collected, after having undergone either refraction or reflec- tion. This point is thus denominated, because the rays being here brought together and united, their joint effect is sufficient to burn bodies exposed to their action; and hence this point is called the focus, or burning point. It must be observed, how- ever, that the focus is not, strictly speaking, a point; for the rays are not accurately collected into one and the same place or point; owing to the different nature and refrangibility of purpose. the rays of light, to the imperfections in the figure of the lens, and other similiar impediments. The focus, therefore, is a small circle which Huygens has demonstrated to be one-eighth the thickness of the lens, when it is convex on both sides; that is, it cannot be less than this, but in imperfect glasses it exceeds the above measure sometimes considerably. - Virtual Focus, or Point of Divergence, so called by Mr. Moly- neux, is the point from which rays tend after refraction or reflection ; being in this respect opposed to the ordinary focus, or point of concurrence, where rays are made to meet after refraction or reflection. Thus, the foci of an hyperbola are mutually virtual foci to each other; but in an ellipse, they are common foci to each other; for the rays are reflected from the other focus in the hyperbola, but towards it in the ellipse. Practical Rules for finding the Foci of Glasses.— 1. To find by experiment, the focus of a convex spherical glass, being of a small sphere; apply it to the end of a scale of inches and decimal parts, of a convenient length, and expose it before the Sun; upon the scale may be seen the brigth intersection of the rays measured out: or, expose it in the whole of a dark cham- ber; and where a white paper receives the distinct representa- tion of distant objects, there is the focus of the glasses. 2. For a glass of a pretty long focus, observe some distant object through it, and recede from the glass till the eye perceives all in confusion, or the object begins to appear inverted; then the eye is in the focus. 3. For a plano-convex glass; make it reflect the sun against the wall ; on the wall will then be seen two sorts of light, a brighter within another more obscure ; withdraw the glass from the wall, till the bright image be in its least dimensions; then is the glass distant from the wall about a fourth part of its focal length. 4. For a double convex; expose each side to the sun in like manner; and observe both the distances of the glass from the wall: then is the first dis- tance about half the radius of the convexity turned from the sun ; and the second is about half the radius of the other con- vexity. The radii of the two convexities being thus known, the focus is then found by this rule: As the sum of the radii of both convexities is to the radius of either convexity, so is dou- . the radius of the other convexity to the distance of the OCUIS. - - - FODDER, or Fother, in Mining, a measure containing twenty-two hundred and a half weight, as of lead, but in Lon- don it is twenty hundred. FOETUS, in Anatomy, a term applied to the offspring of the human subject, or of animals, during its residence in the womb. FOG, or MIST, consisting of condensed vapours floating near the surface of the earth. * Fog Bank, an appearance in hazy weather which frequently resembles land at a distance, but which vanishes as you approach it. w r FOIL, in Fencing, a blunt sword, or one tipped with a button or cork, covered with leather. Foils are used in the noble and manly exercise of fencing. Tim Foil, among Jewellers, is used to give precious stones a colour, by placing it beneath the gem; and this species of foil is manufactured from copper, silver, or gold. The copper foils are known as Nuremberg or German foils, and are prepared as follows:—Procure the thinnest copper, beat it on an anvil with a well polished hammer, as thin as possible; place the copper between two iron plates as thin as writing paper; heat them in the fire; then boil the foil in a pipkin, with equal quantities of tartar and salt, constantly stirring them till by boiling they become white; after which take them out and dry them ; them give them another hammering, till they are made fit for your If too much heated they will melt; if too long boiled, they will attract the salt. Polish them thus:–Take a plate of the best copper 12inches long, 5 inches broad, polished to the greatest perfection; bend this to a long convex, fasten it upon half a roll, and fix to it a bench or table; then take some chalk washed as clean as possible, and filtered through a fine clean linen cloth ; lay some of this on the roll, wet the copper all over, lay the foils on it, and with a polishing stone and the chalk, polish your foils till they are as bright as a looking-glass, after which they must be dried, and laid up free from dust. 3. FOLIATING or Silvering of Looking-Glasses, is spreading the plates over, after they are polished, with amalgam, to reflect 324 F O R. F O O. DICTIONARY OF MECHANICAL SCIENCE. the image. The process is as follows:-A thin blotting paper is spread on the table, and sprinkled with chalk; then a fine leaf of tin-foil is laid over the paper; upon this mercury is poured, and distributed equally over the leaf with a hare's foot, or cotton: over this is laid a clean paper, and over that the glass plate, which is pressed down with the right hand, and the paper drawn out with the left; this done, the plate is covered with a thicker paper, and loaded with a greater weight, that the superfluous mercury may be driven out, and the tin adhere more closely to the glass. Then dry, the weight is removed, and the looking-glass is complete. Some add an ounce of marcasite, melted by the fire; and lest the mercury should evaporate in smoke, pour it into gold water; and when cooled, squeeze it through a cloth or leather. Foliating of Globe Looking-Glasses. Take five ounces of quicksilver, and one ounce of bismuth of lead and tin half an ounce each; put the lead and tin into fusion, then put in the bismuth, and when that is in fusion let it stand till it is almost cold, and pour the quicksilver into it; after this, take the glass globe, which must be very clean, make a paper funnel, which put into the hole of the globe, as near to the glass as you can, pour the amalgam in gently, and move it about, so that it may touch every where. FOMALHAUT, or Foma Haut, a star of the first magnitude in Piscis Australis, marked a by Bayer. Fox1FNTATION, in Medicine, is the external application of a fluid, as warm as the patient can bear it. Two flannel cloths are dipped in that liquor, one of which is wrung as dry as possible, and immediately applied to the part affected. This cloth lies on till the heat has evaporated, and the other is then applied. By this alternate application the part affected is constantly supplied with warmth, for 15 minutes, or half an hour, as occasion may require. FOOD, Comparative Nutritive Properties of . An interesting report on this subject has lately been presented to the French inister of the interior, by Messrs. Percy and Vauquelin, members of the Institute. The result of their experiments is as follows:–In bread, every 100 lb. is found to contain 80 lb. of nutritious matter; butcher meat, averaging the different sorts, contain only 35 lb. in one hundred; French beans, (in the grain,) 92 lb. in one hundred; broad beans, 891b.; peas, 93 lb.: lentils, (a species of half pea, little known in Britain,) 94 lb. in one hundred ; greens and turnips, which are the most aqueous of all vegetables used in culinary purposes, furnish only 8 lb. of solid nutritious substance in one hundred; carrots, (from whence an inferior kind of sugar is produced,) 1.4 lb. ; and what is remarkable, as being opposed to the old theory, 100 lb. of potatoes only yield 25 lb. of nutriment; one pound of good bread is equal to 2 lb. of potatoes; and 75 lb. of bread, and 30 lb. of meat, are equal to 300 of potatoes; 3 lb of bread, and 5 oz. of meat, are equal to 3 lb. of potatoes; 1 lb. of potatoes is equal to 4 lb. of cabbage, and 3 lb. of turnips; and one pound of rice bread or French beans is equal to 3 lb. of potatoes. FOOT, a measure of length, derived from the length of the human foot; containing 12 linear inches. Square Foot, is a square whose side is one foot, and is therefore equal to 144 square inches. Cubic Foot, is a cube whose side is one foot, and the cube contains 1728 cubic inches. Foot, in the Latin and Greek poetry, a metre or measure composed of a certain number of long and short syllables. These feet are commonly reckoned twenty-eight, of which some are simple, as consisting of two or three syllables, and there- fore called dissyllabic or trisyllabic feet; others are compound, consisting of four syllables, and are therefore called tetrasylla- bic feet. Foot of a Sail, the lower edge, or bottom. Foot Rope, the rope to which the lower edge of a sail is sewed. Foot Ropes are also the same with Horses of the Yards, which see. Foot Jºaleing, the whole inside planks or lining of a ship, used to prevent any part of her ballast or cargo from falling between her floor timbers. Foot of a Mast, the lowest end or that which goes into the step. Foot Mill, or Tread-Mill, for grinding corn or other sub- stances, moved by the pressure of the feet of men or animals. In some of these mills, a horse or an ox is fixed to a stall upon a floor above a vertical wheel, and a hole is made in the floor in the place where the hind feet of the animal should stand, thus admitting those feet to press upon the rim of a wheel, and cause the wheel to turn upon its axle, and give motion to the whole mill. But in this kind of machine, the animal will be obliged very unnaturally to move his hind feet, while his fore feet will be at rest; and further, the motive force being applied near the vertex of the wheel, will act but with little advantage, and the wo more judicious construction of a foot mill is represented in the above engraving. A, is an inclined wheel, which is turned by the weight of a man, and the impulsive force of his feet while he supports himself, or occasionally pushes with his hands at the horizontal bar H. The face of this wheel has thin pieces of wood nailed upon it at proper distances, to keep the feet of the man from slipping while he pushes the wheel round; and the under side has projecting teeth or waves which catch into the cogs of the trundle B, and by that means turn the horizontal shaft G, with its wheel C ; this latter wheel turns the trundle D, the axle of which carries the upper millstone E. This kind of footmill will answer extremely well to grind malt, &c. when no very great power is required. And as respects the application of animal force to machinery, see pages 325 and 326, of this work, where this matter is treated in all its various relations, both to man and beasts of burden. FORAGE, in Military affairs, denotes the provisions brought into the camp by the troops for the sustenance of the horses. FORCE, in Mechanics, denotes that unknown cause which produces a change in the state of a body, as to motion, rest, pressure, &c.; that is, whatever produces or tends to produce motion, or a change of motion in any body, is called force. According to this definition, the muscular power of animals, as likewise pressure, impact, gravity, &c. are considered as forces, or sources of motion, it being evident, from daily expe- rience, that bodies exposed to the free action of any of these, are either put into motion, or have their state of motion chang- ed. All forces, however various, are measured by the effects they produce in like circumstances, whether the effect be creat- ing, accelerating, retarding, or deflecting motions; the result of some general and commonly observed force is taken for unity, and with this any others may be compared; and their proportions represented by numbers or lines. Under this point of view they are considered by the mathematician; all else falls within the province of the universal philosopher, or the metaphysician. When we say that a force is represented by a right line, A B, it is to be understood that it would cause a material point, situated at rest in A, to run over the line A B, which is called the direction of the force, so as to arrive at B at the end of a given time, while another force would cause the F O R. F O R. 325 DiCTIONARY OF MECHANICAL SCIENCE. same point to have moved a greater or less distance from A in the same time. See the figure below. Mechanical forces may be reduced to two sorts; one of a body at rest, the other of a body in motion. The former is that which we conceive as residing in a body when it is supported by a plane, suspended by a rope, or balanced by the action of a spring, &c., being denominated pressure, tension, force, or vis mortua, solicitatio, conatus movemdi, and which may always be estimated or measured by a weight, viz. the weight that sustains it. To this class of forces may also be referred centripetal and centrifugal forces, though they reside in a body in motion, because these forces are homogeneous to weights, pres- sures, or tensions of any kind. The force of a body in motion, is a power residing in that body, so long as it continues its motion; by means of which, it is able to remove obstacles lying in its way, to lessen, destroy, or overcome the force of any other moving body, which meets it in an opposite direction ; or to surmount any the largest dead pressure or resistance, as ten- sion, gravity, friction, &c. for some time; but which will be lessened or destroyed by such resistance as lessens or de- stroys the motion of the body. This is called vis motura, moving force, or motive force, and by some late writers vis viva, to distinguish it from the vis mortua, spoken of before. Force, is distinguished into motive and accelerative, or retardive, constant, variable, &c. Motive Force, otherwise called momentum, or force of per- cussion, is the absolute force of a body in motion, &c.; and is expressed by the product of the weight or mass of matter in the body, multiplied by the velocity with which it moves. Motive Force also denotes the force by which a system of bodies is put in motion, as it is the difference between the power or weight which produces the motion, and the resistance or weight to which it is opposed. } Accelerative Fokce, or retardive force, is that which respects the velocity or rate of motion only, accelerating or retarding it; and it is denoted by the quotient of the motive force, divided by the mass or weight of the body. So, If m denote the motive force, and b the body, or its weight, and f the accelerating or retarding force, 7% b - Constant Force, is such as remains and acts continually the same for some determinate time. Such, for example, is the force of gravity, which acts constantly the same upon a body while it continues at the same distance from the centre of the earth, or from the centre of force, wherever that may be. Constant or uniform forces produce uniformly accelerated motions, the laws of which will be found under the article ACCELERATION. Variable Force, is that which is continually changing its effect and intensity, such as the force of gravity at diſſerent distances from the earth’s centre. See the formulae relating to variable forces under the article ACCELERATION. Forces are farther distinguished into central, centrifugal, &c. which see under the several articles. Composition of Forces, may be thus defined:—If two or more forces differently directed, act upon the same body, at the same time, as the body in question cannot obey them all, it will move in a direction somewhere between them. This is called the composition and resolution of forces or of motion, and may be illustrated in the following manner:—Illus. Sup- pose a body A to be acted upon by a force in the direction AB, while at the same time it is im- C pelled by another force in the direction A C, it wiil then move in the direction A D ; and if the lines A B, A C, be made of lengths proportionate to the forces, and the lines C D, D B, be drawn “A B parallel to them, so as to complete the parallelogram A B D C, , then the line which the body A will describe, will be the diagonal A D ; and the length of this line will represent the force with which the body will move. But if the body be im- pelled by equal forces acting at right angles to each other, it will move in the diagonal of a square. Instances in nature, of motion produced by several powers acting at the same time, are innumerable. A ship impelled by the wind and tide is one then is f as D what was spent in its elevation. well known; a paper kite, acted upon in one direction by the wind and in another by the string, is another instance. Animal Force, as applied to Machinery. All machines are impelled, either by the exertion of animal force, or by the application of the powers of nature. The latter comprise the potent elements of water, air, and fire. The former is more common, yet so variable as hardly to admit of calculation; it depends not only on the vigour of the individual, but on the different strength of the particular muscles employed. Every animal exertion is attended by fatigue; it soon relaxes, and would speedily produce exhaustion. The most profitable mode of applying the labour of animals, is to vary their muscular action, and revive its tone by short and frequent intervals of repose. . - The ordinary method of computing the effects of human labour is, from the weight which it is, capable of elevating to a certain height, in a given time, the product of these three num- bers expressing the absolute quantity of performance. This was reckoned by Daniel Bernoulli and Desaguliers at two mil- lions of pounds avoirdupois, which a man could raise one foot in a day. But our civil engineers have gone much farther, and are accustomed, in their calculations, to assume, that a labourer will lift ten pounds to the height of ten feet every second, and is able to continue such exertion for ten hours each day, thus accumulating the performance of 3,600,000. But this estimate seems to be drawn from the produce of momentary exertions, under the most favourable circumstances; and it therefore greatly exceeds the actual results, as commonly depressed by fatigue, and curtailed by the unavoidable waste of force. Coulomb has furnished the most accurate and varied obser- vations on the measure of human laboar. A man will climb a stair, from 70 to 100 feet high, at the rate of 45 feet in a minute. Reckoning his weight at 155 lbs., the animal exertion for one minute is 6,975, and would amount to 4,185,000 if continued for ten hours. But such exercise is too violent to be often repeated in the course of a day. A person may clamber up a rock 500 feet high by a ladder-stair in twenty minutes, and consequently at the rate of 25 feet each minute; his efforts are thus already impaired, and the performance reaches only 3,875 in a minute. - . But, under the incumbrance of a load, the quantity of action is still more remarkably diminished. A porter weighing 140 lb. was found willing to climb a stair 40 feet high 266 times in a day; but he could carry up only 66 loads of fire-wood, each of them 163 lb. weight. In the former case, his daily performance was very nearly 1,500,000; while, in the latter, it amounted only to 808,000. The quantity of permanent effect was hence only about 700,000, or scarcely half the labour exerted in mere climbing. In the driving of piles, a load of 42 lb., called the ram, is drawn up 33 feet high 20 times in a minute; but the work has been considered so fatiguing as to endure only three hours a day. This gives about 530,000, for the daily perfor- mance. Nearly the same result is obtained, by computing the quantity of water, which by means of a double bucket, a man drew up from a well. He liſted 36 lb. 120 times in a day from a depth of 120 feet, the total effect being 518,400. A skilful labourer working in a field with a large hoe, creates an effect equal to 728,000. When the agency of a winch is employed in turning a machine, the performance is still greater, amounting to 845,000. In all these instances, a certain weight is heaved up, but a much smaller effort is sufficient to transport a load horizontally. A man could, in the space of a day, scarcely reach an altitude of two miles by climbing a stair; though he will easily walk over thirty miles on a smooth and level road. But he would in the same time carry only 130 lb. to the fourth part of that distance, or 74 miles. Assuming his own weight to be 140 lb., the quantity of horizontal action would amount to 42,768,000, or twenty-eight times the vertical performance; but the share of it in conveying the load is 20,961.780, or about thirty times The greatest advantage- is obtained by reducing the hurden to 102 lb., the length of jour- ney being augmented in a higher ratio. z - . These results are apparently below the average of English labour, which is not only most vigorous, but, in many cases, quite overstrained. Moderate exertion of strength, joined to 4 O 326 F O R. F o R DICTIONARY OF MECHANICAL SCIENCE. regularity and perseverance, would be more conducive to robust health, and the comfortable duration of human life. * A porter in London is accustomed to carry a burden of 200 lb. at the rate of three miles an hour. In the same metro- polis, a couple of Irish chairmen continue at the pace of four miles an hour, under a load of 300 lb. These exertions are greatly inferior, however, to the labour performed by porters in Turkey, the Levant, and generally on the shores of the Mediterranean. At Constantinople, an Albanian porter will carry 800 or 900 lb. on his back, stooping forward, and assist- ing his steps by a sort of staff. At Marseilles, four porters commonly carry the immense load of nearly two tons, by means of soft hods passing over their heads, and resting on their shoulders, with the ends of poles, from which the goods are 'suspended. - . - According to some experiments of the late Mr. Buchanan, the exertions of a man in working a pump, in turning a winch, in ringing a bell, and in rowing a boat, are as the numbers 100, 167, 227, and 248. But those efforts appear to have been con- tinued for no great length of time. The Greek seamen, in the Dardanelles, are esteemed more skilful and vigorous in the act of rowing, than those of any other nation. Even the Chinese, applying both their hands and their feet, are said to surpass all people in giving impulsion to boats by sculling. The several races of men differ materially in strength, but still greater diversity results from the constitution and habits of the individual. The European is, on the whole, decidedly more powerful than the inhabitants of the other quarters of the globe; and man, reared in civilized society, is a finer, robuster, and more vigorous animal than the savage. In the temperate climates, likewise, men are capable of much harder labour, than under the influence of a burning sun. Coulomb remarks, that the French soldiers employed on the fortifications of the Isle of Martinique became soon exhausted, and were unable to perform half the work executed by them at home. The most violent and toilsome exertion of human labour is performed in Peru, by the carriers or cargueros, who traverse the loftiest mountains, and clamber along the sides of the most tremendous precipices, with travellers seated on chairs strap- ped to their backs. In this manner, they convey loads of 12, 14, or even 18 stones; and possess such strength and action, as to be able to pursue their painful task eight or nine hours, for several successive days. These men are a vagabond race, consisting mostly of mulattoes, with a mixture of whites, who prefer a life of hardship and vicissitude, to that of constant though moderate labour. When a man stands, he pulls with the greatest effect; but his power of traction is much enfeebled by the labour of tra- velling. If v denote number of miles which a person walks in an hour, the force which he exerts in dragging forward a load will be expressed nearly by (12–2w)”. Thus, when at rest, he pulls with a force of about 29 pounds averdupois; but if he walks at the rate of two miles an hour, his power of traction is reduced to 14 lb.; and if he quicken his pace to four miles an hour, he can draw only 3 lb. There is consequently a certain velocity which procures the greatest effect, or when the pro- duct of the traction by the velocity becomes a marimum. This takes place when he proceeds at the rate of two miles an hour. The utmost exertion which a man walking might continue to make in drawing up a weight by means of a pulley, would amount, therefore, in a minute, only to 2,430; but if he applied his entire strength, without moving from the spot, he could produce an effect of 3,675. The labour of a horse in a day, is commonly reckoned equal to that of five men ; but then he works only eight hours, while a man easily continues his exertions for ten hours. Horses likewise display much greater force in carrying than in pulling; and yet an active walker will beat them on a long journey. Their power of traction seldom exceeds 144 pounds, but they are capable of carrying more than six times as much weight. The pack-horses in the West Riding of Yorkshire are accus- tomed to transport loads of 420 lb. over a hilly country. But, in many parts of England, the mill-horses will carry the enor- mous burden of 910 lb. to a short distance. With regard, how- ever, to the ordinary power of draught, the formula (12—v)? where v denotes the velocity in miles an hour, will perhaps be of Arabia. 1 night. found sufficiently near the truth. Thus, a horse beginning his pull with the force of 144 lb., would draw 100 lb. at a walk of two miles an hour, but only 64 lb. when advancing at double that rate, and not more than 36 lb. if he quickened his pace to six miles an hour. His greatest performance would hence be made with the velocity of four miles an hour. The accumulated effort in a minute will then amount to 22,528. The measure generally adopted for computing the power of steam engines is much higher, the labour of a horse being reckoned sufficient to raise, every minute, to the elevation of one foot, the weight of 32,000 lb. But this estimate is not only greatly exaggerated, but should be viewed as merely an arbitrary and conventional standard. . Wheel carriages enable horses, on level roads, to draw, at an average, loads about fifteen times greater than the power exerted. The carriers between Glasgow and Edinburgh trans- port, in a single-horse cart, weighing about 7 cwt., the load of a ton, and travel at the rate of 22 miles a day. At Paris, one horse, in a small cart, conveys along the streets, half a cord of wood, weighing two tons; but three horses yoked in a line are able to drag 105 cwt. five and a fourth, or that of a heavy cart loaded with building stones. The Normandy carriers travel from 14 to 22 miles a day, with two-wheeled carts, weighing each 11 cwt., and loaded with 79 cwt. or nearly 4 tons, of goods, drawn by a team of four horses. - The French draught horses, thus harnessed to light car- riages, are more efficient perhaps than the finer breeds of this country. They perform very nearly as much work as those in the single-horse carts used at Glasgow, and far greater than those heavy animals which drag the lumpish and towering English waggons. The London dray-horses, in the mere act of ascending from the wharfs, display a powerful effort, but they afterwards make little exertion, their force being mostly expended in transporting their own ponderous mass along. Oxen, on account of their steady draught, are in many countries preferred for the yoke. They were formerly em- ployed universally in the various labours of husbandry. The tenderness of their hoofs, unless shod, however, makes them unfit for pulling on paved roads, and they can work only with advantage in soft grounds. But they want all the pliancy and animation, which are the favourite qualities of the horse. The patient drudgery of the ass, renders him a serviceable companion of the poor. Though much inferior in strength to the horse, he is maintained at far less cost. In this country, an ass will carry about two hundred weight of coals or lime- stone, twenty miles a day. But, in the warmer climates, he becomes a larger and finer animal, and trots or ambles briskly under a load of 150 pounds. The mule is still more powerful and hardier, being ſited equally for burden and draught. In the hotter parts of Asia and Africa, the ponderous strength of the elephant has been long turned to the purposes of war. He is reckoned more powerful than six horses, but his con- sumption of food is proportionally great. The elephant carries a load of three or four thousand pounds,-his ordinary pace is equal to that of a slow trot, he travels easily over forty or fifty miles in a day, and has been known to perform, in that time, a journey of a hundred and ten miles. His sagacity and intelligence direct him to apply his strength according to the exigency of the occasion. The camel is a most useful beast of burden in the arid plains The stronger ones carry a load of ten or twelve hundred weight, and the weaker ones transport six or seven hundred; they walk at the rate of two miles and a half in an hour, and march about thirty miles every day. The camel tra- vels often eight or nine days, without any fresh supply of water; when a caravan encamps in the evening, he is perhaps turned loose, for the space of an hour, to browze on the coarsest her- bage, which serves him to ruminate during the rest of the In this manner, without making any other halt, he will perform a dreary and monotonous journey of two thousand miles. - Within the Arctic Circle again, the rein deer is a domesti- cated animal, not less valuable. He not only feeds and clothes the poor Laplander, but transports his master with great swift- ness, in a covered sledge, over the snowy and frozen tracts. The rein deer subsist on the scanty vegetation of moss or fo R. F o R: 327 DICTIONARY of MECHANICAL scIENCE. lichens, and, though very docile, they are not powerful. Two of them are required to draw a light sledge: so harnessed, they will run fifty or sixty miles on a stretch, and sometimes per- form a journey of a hundred and twelve miles in the course of a day. But such exertions soon wear them out. A sort of dwarf camel was the only animal of burden pos- sessed by the ancient Peruvians. The Lama is, indeed, pecu- liarly fitted for the lofty regions of the Andes. The strongest of them carry only from 150 to 200 pounds, but perform about fifteen miles a day over the roughest mountains. They gene- rally continue this labour during five days, and are then allowed to halt two or three days before they renew their task. The Paco is another similar animal, employed likewise in trans- porting goods in that singular country; it is very stubborn, however, and carries only from fifty to seventy pounds. Even the exertions of goats have, in some parts of Europe, been turned to useful labour. They are made to tread in a wheel which draws water, or raises ore from the mine. Though a very light animal, the goat is nimble, and climbs at a high angle. Supposing this soaring creature, though only the fourth part of the weight of a man, to march as fast along an ascent of 40 degrees, as he does over one of 18 degrees, the sine of the former being double that of the latter, it mus; yet perform half as much work.-Leslie's Elements of Natural Philosophy. FORCEPS, in Surgery, &c. a pair of scissars for cutting off, or dividing, the - - fleshy membranous parts of the body, as occasion requires. FORCER, TeM por ARY, for a pump, is a contrivance to produce a constant stream. A very simple forcer of this kind has been devised by Mr. R. Trevi- thick: it consists in fixing a barrel with ! solid piston along the side of the common d pump, in such a manner that the lower space of the additional barrel may com- municate with the space between the two valves of the pump; and lastly, by con- necting the rods at D, so that they may work together. This is shewn in the annexed figure, and the effect is, that when the pistons are raised, the spaces of the cylinders beneath, A and B, be- come filled by the pressure of the atmo- sphere, at the same time that the upper column flows out at E, the discharging Spout. . But again, when the pistons descend, the valve C shuts, and consequently, the water driven by the piston in B must ascend through A, and continue to pro- duce an equal discharge through E in the down stroke. FORCING, among Gardeners, signifies the making trees produce ripe fruit before their usual time. This is done by planting them in a hot-bed against a south wall, and likewise defending them from the injuries of the weather by a glass frame. They should always be grown trees, as young ones are apt to be destroyed by this management. The glasses must be taken off at proper seasons, to admit the benefit of fresh air, and especially of gentle showers. * FORE, the distinguishing character of all that part of a ship's frame and machinery which lies near them. Fore and Aft, throughout the ship’s whole length, or from end to end; it also implies, in a line with the keel. Fore Bow Line, the bow-line of the fore-sail. See Bow LINE. Fore Braces, ropes applied to the fore yard-arms, to change the position of the fore-sail occasionally. ** . Fore Castle, a short deck placed in the fore part of a ship above the upper deck; it is usually terminated both before and behind in vessels of war by a breast-work, the foremost part | forming the top of the beak head, and the hind part reaching to the after part of the fore chains. Fore Castle Men, sailors statiotled on the fore castle, who are generally prime seamen. Fore Cat-Harpings, a complication of ropes used to brace in the upper part of the fore shrouds. Forte Closed, in Law, signifies the being shut out, and excluded or barred, the equity of redemption on mortgages, &c. Fore Foot, a piece of timber which terminates the keel at the fore end; it is connected by a scarf to the extremity of the keel, and the other end of it which is incurvated upwards into a sort of knee, is attached to the lower end of the stem ; it is also called a gripe. As the lower arm of the fore foot lies on the same level with the keel, so the upper one coincides with the middle line of the stem ; its breadth and thickness there- fore correspond with the dimensions of those pieces, and the heel of the cutwater is scarfed to its upper end. • For E Land, a cape or promontory projecting into the sea, as the North and South Forelands. FoRe Tackle, tackle on the fore mast, and also tackle used for stowing the anchor. Foretop Men, men stationed in the foretop, in readiness to set, or take in the smaller sails, and to keep the upper rigging in order. For E Runner of the Ling, a small piece of red buntin, laid into that line at a certain distance from the log, the space between them being called the stray line, which is usually from twelve to fifteen fathoms, and is an allowance for the log to be entirely out of the ship's dead water, before they begin to esti- mate the ship's velocity, consequently the knots begin from that point. See the article. Log. Fore Staff, is an instrument used at sea for taking the altitudes of heavenly bodies. The fore staff, called also cross staff, takes its denomination hence, that the observer in using it turns his face towards the object, in contradistinction to the back staff, where he turns his back to the object. FOREIGN SEAMEN, serving two years on board British ships, whether of war, trade, or privateers, during the time of war, shall be deemed natural-born subjects. FOREJUDGER, in Law, a judgment whereby a man is deprived, or put out, of the thing in question. FOREST, in Law, a certain territory of woody ground and fruitful pastures, privileged for wild beasts and fowls of forest, chase, and warren, to rest and abide under the protection of the king, for his princely delight. Every forest is supposed to be bounded by unremovable marks and meres, either known by matter of record or prescription. Besides the New Forest in Hampshire, there are 68 other forests in England, 13 chases, and more than 700 parks. New Forest lies on the sea side, Hampshire, Kirwood forest is on the banks of the Trent, Dean forest on the Severm, and Windsor forest on the Thames. A forest strictly taken cannot be in the hands of any but the king, who alone has power to grant a commission to the justice in eyre of the forest; yet if he grants a forest to a subject, that subject and his heirs shall have a justicias in the forest, in which case the subject has a forest in law. Beasts of the forest are the hart, hind, buck, doe, bear, wolf, fox, hare, For EST Courts take cognizancee of all trespasses committed in the said forests, whether these be injuries done to the veni- son, the vert, or greensward, or to the covert in which such deer are lodged. And the forest laws are laws peculiarly appli- cable to the forests, being different from the common law of England. - FORESTALLING, is the buying or bargainiug for any corn, cattle, or other merchandise, by the way, before it comes to any market or fair to be sold ; or as it comes from beyond the seas, or otherwise, towards any port or creek of this realm, to sell the same again at a higher price. At the common law, all endeavours to enhance the price of merchandise, and all prac- tices which have a tendency thereto, whether by spreading false rumours, or by purchasing things in a market before the accus- tomed hour, or by buying and selling again the same thing in the same market, or by such devices, are criminal, and punish- able by fine and imprisonment. FORESTER, a sworn officer of the forest, appointed by the king's letters patent to walk the forest at all hours, watch over the vert and venison; also to make attachments and true pre- sentments of all trespasses committed within the forest. FORFEITURE, in Law, a transgression, or offence, or more properly speaking, the effect of such transgression, as the loss of privilege, right, estate, honour, office, or effects, either in civil or criminal cases. In civil cases, as when a tenant in tail makes leases not warranted by the statute, a forfeiture is com- F O R. F O. R. DicTIONARY OF MECHANICAL scIENCE. mitted, and he who has the immediate reversion may enter upon possession. In criminal cases, it is two-fold; of real and personal estates, as by attainder in high treason; or in petty treason and felony, of all chattel interests absolutely, and the profits of all freehold estates during life and after death, of all lands and tenements in fee simple (but not those in tail), to the crown for a year and a day, &c. Lands are forfeited upon attainder, and not before ; goods and chattels are forfeited by conviction. • - FORFICULA, Earwig, an insect of the coleoptera order. The wings of this insect are remarkably elegant, and are con- voluted beneath their small sheaths in a curious manner; they are very large in proportion to the animal, transparent, and slightly iridescent. The earwig flies only by night, and it is with difficulty made to expand its wings by day. The popular dread in which this insect is held, on a supposition of its some- times entering the ear, and piercing the timpanum, is con- sidered by some as problematical, though there are undoubtedly instances of earwigs having accidentally taken shelter in the ears of persons asleep, and occasioning great pain. The best means of expelling them is, to drop a small quantity of brandy or other spirit into the ear. FORGE, a little furnace, as that used by smiths, &c. or, simply, a pair of bellows, the muzzle of which is directed upon a smooth area, on which coals are placed. See BELLows.— . Forge is also used when speaking of a large furnace, wherein iron ore taken out of the mine, is melted down; or it is more properly applied to another kind of furnace, wherein the iron ore melted down and separated in a former furnace, and then cast into sows and pigs, is heated and fused over again, and beaten afterwards with large hammers, and thus rendered more soft, pure, ductile, and fit for use. Forge Blowing Engine, by Mr. Paterson, Lanark. The improvement in this blowing engine is, that by the use of two cylinders blowing alternately, the blast is equalized without either a water-pressure or an air-vessel; and thus, without the aid of these, and with less weight upon the moving power, whether steam-engine or water-wheel, a constant and steady blast is obtained. * Description.—This machine has been used for some time back. It is driven by a water-wheel of five horse power, and has been found preferable to a blast from one cylinder. Mr. Paterson can smelt at least one-third more iron with the same quantity of coke, and make larger pigs; and besides, the iron is much more fluid or better fused, than was the case when he used the blowing engine with one cylinder. He farther considers it a great advantage for the machinery, as it entirely does away jolting, the crank being alike strained at all points. A, (see the engraving,) the upright cylinder; B, the horizontal cylin- der; C, C, the two connecting rods; D, the crank; E, the walking beam ; F, the parallel motion; G, the pipes for con- veying the blast to the cupola; H, the cupola or furnace ; I, the small wheel, running upon a cast iron bar, with a groove in its top, in order to keep the oiston rod parallel ; K, is two cast iron plates standing on edge, to allow the connecting rod to move between them, and to support the upright cylinder; L,L, the chests where the valves are placed to admit the air into the upright cylinder, but they cannot be shewn in the plate. The valves in the horizontal cylinder are fixed to the ends of the cylinder, and open inwards to admit the air into it. M, M, the pedestals for the cylinder and crank to be fixed upon ; N, the spring beams for carrying the walking beam; O, a beam to go across the house to support the spring beams and the walking beams.-Glasgow Mech. Mag. For GE Furnace. The forge furnace consists of a hearth, upon which a fire may be made, and urged by the action of a large pair of double bellows, the nozzle of which is inserted through a wall or parapet constructed for that purpose. Black lead pots, or small furnaces of every desired form, may be placed, as occasions require, upon the hearth ; and the tube of the bellows being inserted into a hole in the bottom of the furnace, it becomes easy to urge the heat to almost any degree required. Forge Hammer, moved by steam. We shall here present our readers with a recent application of steam to work a forge hammer, which from the engraving and description, must be easily understood by all persons connected with iron factories. Fig.2 |e * \ .9 *º gº \ * 6 Y \º Wºry. a gºº FigZ .* º |iſ, gººk". ſº #. LA ſº | \ I A ||\ É ||| | r ) º Zº i jº. - F F Description.—A, the cylinder, the bottom, n, of which is kept very hot by the fire in the stove, S. B, the beam, vibrating on a centre, C. D, the anvil. E, the iron to be forged. F, F, F, the foundation or floor for the machine to rest on. G, a cistern, filled with water as high as t, and the remaining part with air. H, the hammer. I, a weight, heavy enough to lift the hammer, and to overcome the friction of the machine. K, a pair of smith's bellows inverted, which receives motion from the beam, B, by means of the connecting rod, Q. L, an upright shaft, fastenca to the top of the cylinder, A, to which the radius rod of the parallel motion, P, is fixed. R, a rod to let water into the cylinder, move the forcing pump, Z, and let steam out of the cylinder. This rod has a hole in it about one-eighth of an inch long; and when the hammer is at its greatest height, as is shewn in the figure, this rod is at the bottom; the hole, a, comes opposite to the pipe, p, and allows the water to be forced out of the cistern, G, into the cylinder, A, (which is made air-tight at top, m, and rather broader in the inside, to allow the water to pass to the bottom, n,) which is immediately con- verted into steam, and thus gives a very great force to the hammer. This rod at the same time shuts the communication with the atmosphere, by means of the pins a ſc, and crank c, more fully exhibited in fig. 2. When the end, Y, of the beam is at the top, the bottom pin, a, lifts up the crank, e, and allows the steam to pass through the groove g, (which is made in the steel cock, c g, exactly to the centre,) into the atmosphere, and allows the piston to descend. The piston of the forcing pump, Z, is also lifted by this rod by the catch, f; but as the beam descends, it does not force down the piston, but lets the weight, w, force the water up the pipe, T, according as it is consumed. w, a cock for stopping the engine.—London Mech. Mag. FORGERY, in Common Law, the fraudulent making or | altering of writing to the prejudice of another man's right; for which the offender may suffer imprisonment, banishment, death. Forgeries in court rolls, wills, deeds, bonds, acquit- | tances of debts, are all felonies; in bank bills, bills of credit, promissary notes, stamps, &c. felonies without benefit of clergy; aiding and abetting in any forgery of a deed, bond, bill of F O R F O R DICTIONARY OF MECHANICAL scIENCE. 329 exchange, indorsement, assignment, &c. is felony without benefit of clergy. See PRINTING. FORLORN Hope, in the Military art, signifies men detached from several regiments, or otherwise appointed, to make the first attack in day of battle, or at a siege to storm the counterscarp, mount the breach, or the like. They are so called from the great danger they are unavoidably exposed to. FORM, PRINTER’s, an assemblage of letters, words, and lines, disposed into pages by the compositor, and from which the printed sheets are taken. FORMA PAUPERIs, in Law, is when any person having cause of suit, and cannot support the charges, upon affidavit, that he is not worth five pounds, the court admits him to sue without fees or paying costs. FORMATIONS, the rocks and other solid arrangements of matter, of which the globe is composed, are considered by geologists as having been formed at different times; and hence they speak of older and later formations, limestone formations, sandstone formations, and such like. FQRMIATES, compounds of the formic acid with earths, alkalies, and metallic oxides. FORMIC ACiD, is obtained from ants, either by simple dis- tillation, or by infusing them in hot water, and afterwards distilling. It may afterwards be purified by repeated rectifica- tion, or it may be done in the time of frost. This acid has been employed by quacks to relieve the pain of the toothache. #t has a very sour taste, and remains liquid at a low tempera- ture. Specific gravity at 680 is 1:1168. FORMICA, the Ant, a well-known insect of the class hyme- noptera. There are eighteen species, which live in a social state, and are divided into males, females, and neutrals. These last conduct the business of the nest, which is usually placed at a little distance from the surface, in some slight elevation prepared by the insects themselves, or previously formed by moles, &c. Ants feed on animal and vegetable substances, devouring caterpillars, &c. as well as fruits. FORMULA, or Form, in Analysis, is any general theorem or literal expression, and is said to be algebraical, logarithmic, trigonometrical, &c. according as it relates to either of these subjects. FORNICATION, the act of incontinency in single persons; for if either party be married, it is adultery. The spiritual court hath the proper cognizance of this offence; but formerly the courts-leet had the power to inquire of and punish forni- cation and adultery; in which courts the king had a fine assessed on the offenders, as appears by the book of doomsday. FORT, a small fortified place environed with a moat, ram- part, and parapet. Forts are of different figures and magni- tudes. Some are fortified with bastions, and others with demi- bastions. See the following articles. FORTIFICATION, a species of Military Architecture, con- sists of the planning and erecting of such works of defence, agreeably to geometrical principles, as may protect a town, or any position, from the capture of an enemy. But the reader must not expect here to find a treatise on each branch of the art. Confining ourselves to facts and terms, our observations will savour more of definitions than rules for practice. Fortification is usually divided into ancient and modern; offensive and defensive ; regular and irregular. - Ancient Fortification consisted principally of defences con- structed with trunks and branches of trees, mixed with earth, for security against the attacks of an enemy. Afterwards, when battering rams, catapults, and other instruments of attack were invented, fortifications were constructed of thick walls of brick or stone, with towers, placed at suitable distances. The object of Modern Fortification is to furnish defence against assailants with fire-arms; the walls are turned into ramparts, the towers into bastions, defended by numerous outworks, so constructed that they cannot be beaten down but by the fire of cannon. The works are contrived so, that one part flanks or defends another, and render the approach of the besiegers to any part very dangerous. Regular Fortifications, are erected in the shape of regular polygons, the sides being at least a musket-shot from each other, and fortified according to the rules of art. See BAstion. – Irregular Fortifications, on the contrary, are those whose sides and angles are not uniform, owing to some irregularity of the ground. These usually occur in Field Fortification, or the constructing of temporary works for an army intrenched, or fortified in the field. In this position it covers a country, supplies the want of numbers, stops a Superior enemy, or obliges him to engage at a disadvantage. The materials used for field fortifications, are such as can be readily obtained, viz. sand bags, earth, and fascines, or fagots of small wood, ten feet long and one foot thick, fastened to the parapet by pickets driven obliquely into the bank. Turf is sometimes used when wood cannot be procured, being four inches thick and eighteen inches square. Bridges of boats are employed for facilitating the transport of troops across deep rivers, and arms or straits of the sea. See BAstion. A new method of Defending Ships and Fortifications against Cannon-balls, and of causing them to fly back again on the Enemy. By Lewis Gompertz, Esq. Having made some experiments on a plan which I had designed, for rendering ships and fortifications shot-proof, and of causing several of the balls which might be fired against them, to return upon the enemy; and having found my experi- ments (which were on a small scale) to answer my expec- tations, I have here to explain the nature of the plan, with the hopes that it may be farther considered by those, whose scien- tific and practical information qualify them for judging how far it might succeed on a large scale. But before I enter into this description, I think it proper to observe, that the chief utility it may promise, is in its appli- cation to merchant vessels, ships of passage, &c. and for fortifications; but for ships of war (as it could be adopted by both parties) its effect would become neutralized, though it seems, that, even in this case it. would save the men from injury, and would always be in favour of the weak and defen- sive side, its nature being that of defending itself, and return- ing the blows, but without any power of attacking, unless furnished with guns also. * * Figs, 4 and 5, shew two views of a ship made on the plan; fig. 3, is a section of a side drawn larger; the form of it being apparent by the drawing. In the three figures, 3, 4, and 5, the same letters refer to the same parts. NW A L is a concave curve to return the balls which strike it, and PC O is a trian- gular piece (extending beyond N M and LK) which goes all round the ship, to protect the most perpendicular part of the curve W A from being struck directly, (otherwise it would be easily perforated,) and which triangular piece, on being struck somewhat horizontally, evades the balls, and guides them pro- perly to the return part N.W.A L, so that they follow the shape of it, and return. The part N M above the curve where the port-holes are, and the part L. K Q below it, are made oblique, to evade those balls which strike them, the part N M sending them upwards, and the part L. K Q directing them into the water, though it must be confessed, that some of the former would thereby occasionally be thrown into the rigging. There are a number of supports shewn near P, fig. 4, and also faintly expressed in fig. 5, which fasten the triangular piece to the ship, and the more acute the outward angle is, the less force will it generally be struck with. Fig. 1, is also a section of a side of a different construction, but inferior, and less applicable; though, being more simple, and on nearly the same principles, I will describe the nature of that first, or rather both together, the same reasoning apply- ing to each. B C is the side forming an acute angle with the water, and extending some way under the water, but not far, as balls do not generally penetrate that part of a ship which is far below the surface of the water. S T is a board placed as shewn, shaded, so that there shall exist a vacancy between itself and the side of the ship; this vacancy grows progressively less upwards, till there is only room left for a ball to pass; and the board is fastened by different supports in places to the ship, but these are not put in this figure, as they would hide the operation. The part W is so curved as to return the balls after they have struck the inclined part, but as in this con- struction the return part might be struck by balls coming directly against it, without their having struck the inclined part, it might be required to make the most perpendicular 4 P 330 F O. R. F. O. R. DICTIONARY OF MECHANICAL SCIENCE. place of it near P, strong enough to resist the balls, this por- tion of the curve being very small. The effects then will vary in different cases, and will depend on the hardness, and on the elasticity, of the material of the side of the ship, and of the ball; also on the force with which the balls are fired. The following results, it seems, would then be produced:– Case 1. If the ball and the side were perfectly elastic, and of sufficient hardness not to be broken, or if only the side were perfectly elastic, then, according to the established law, the ball would be reflected backwards and forwards in fig. 1, between the side C B and board ST, and in fig. 3, between IC Fig. 4. †-º- º - - < ºr - shewn dotted at IP Q.) and it would then return to a ; and in fig. 3, if it should strike at H, it would proceed in the direction of the whole shape N.W.A L, (the motion of the centres being shewn dotted at HIJ R.) and it would return as the arrows point; but if, in fig. 1, it should strike at V, or in fig. 3, at G, the respective balls would, after sliding or rolling up the boards TS fig. 1, and I C, fig. 3, strike each of the curves in such a direction as to follow their shapes and return, without any reflection taking place; and in fig. 3, those balls which entered at G would return at ar, and vice versa. Case 2. If the force of the ball K, fig. 1, should only be so far evaded by the inclination of the side, as to penetrate to about half the depth of its own size or less, (shewn large at ry, fig.2) and IH, at equiangles, and would not follow the shape of the curve; and if the force of the ball should not be too much destroyed by the operation, it would at last be reflected off, though most likely not in a proper direction to reach the enemy. 2dly. If neither the side nor the ball should possess any elasticity, and the side were perfectly hard, whether the ball should be hard, or whether it should be soft, (so as to indent,) it would be turned out of the direction, and would in fig. 1, if struck at H, proceed up the inclined side B C, then following the shape of the curve W., (the motion of the centre being Fig. 5. and if there were no elasticity in the substances, there would, it seems, then arise a great force to repel the ball beyond what is immediately caused by the inclination of the side, on account of the rotary motion the ball would have acquired by its action against the inside of the indentation; then suppose B.A. H Q, fig. 2, be a section of a ball going nearly in a parallel direction CB, and suppose IKLQ be the indentation, in which place we will fancy the substance of the side to be so hard as not to give way any more; the effect, it seems, would then be, that the centre of the ball B would begin to describe part of a circle BN, about the centre I, (the point where the indentation and the remainder of the side meet, and of the size of the ball itself.) Then, if the indentation should be deep F O R. F O R. DICTIONARY OF MECHANICAL SCIENCE, 331 and the velocity great, the ball would be forced completely out of it, and fly far above the top of the ship, because the part of the circle BN which the centre B of the ball would begin to describe, would be nearly perpendicular to the side S D, and as there would be nothing to change the direction of the ball after it had once acquired this new motion, it would fly off in the direction of the most perpendicular part of the circle BN, and continue in this direction, though not of the continued circle BN, but in a straight line B R ; if, however, the inden- tation should be small, the line B R would be more nearly parallel to the side S D, in which case, the motion of the ball would not be caused to differ so much from the direction of the side, but that it might strike the flat board T. S., fig. 1, in a direction KV, which would prevent it from flying away, and direct it to the side again, so that it followed the return part and flew back again, after having been reflected backwards and forwards (not by means of any elasticity,) but by the re- action of the inside surface of the indentation against the ball, as before described; and as there would be a loss of force at every blow, each indentation would be less than the preceding one, and each angle of reflection would be more obtuse, as is shewn in fig. 3, till the ball arrived at the return part W.A, so as to follow the shape of it, ceasing sensibly to rebound when the indentation ceased sensibly to take place; but as the inden- tation and point, I, would not be so hard as assumed, the effect would not be exactly as described; though, as there would be a continual tendency for it to be so, according to the hardness of the side, it would be produced to a certain degree, and the ball would accordingly continually widen the indentation, and come out at some other point T, instead of I, fig. 2; and as the new direction would, by the yielding of the substance, be less per- pendicular than when the material was extremely hard, the ball would be the more inclined to follow the curvature of the side, and to return, and the less inclined to fly over the top of the ship, as the angles of reflection would thereby become still more obtuse every time that the indentations it would produce in its course would widen, as just alluded to. It seems that the tendency of being reflected by the reaction of the indentation would exist, in some degree, till the ball was completely buried, allowing the material of the side of the ship to be as deep as the ball; because, suppose the ball be par- tially buried to HM, fig. 2, (above the diameter,) and allowing even that it should still be as much inclined to go in its original direction C B as it was at first, (though it is evident, that it must have acquired some tendency to alter its direction, by the blow, &c.;) then, to see this clearly, to the diameter a y, which is parallel to the side of the ship, draw another diameter V.K, perpendicular to it. It will then be obvious, that as the ball continued to penetrate, it would be opposed at its whole buried surface H K, and it is also plain that if the resistance to the part of the ball between a. and K tended to press the ball upwards, that resistance above this line between a. and W would tend to bury it still deeper; but as the whole of the arc a K would be greater than part of the arc a V, (HV being by hypothesis unburied,) arc a V would always cause most resist- ance; there would consequently be more than a balance of force to press it upwards, which would exist till the ball was wholly buried, but would then cease. But, both in this case and in case 1, the ball is inclined to two modes of acting, either in going up the side, or out of the indentation; that is, by rolling or sliding, both of which would rob the ball of some of its force, by the friction produced, but the less should be the impediments which cause friction, the more would it be inclined to slide, and the more of them there should be, the more would it be inclined to roll, in its course, but even this would also rob the ball of some of its progressive force, and would be partly spent in giving a new motion (of rotation) to it, which would assist it to roll up the side of the ship, or to roll out of the indentation; but it must be particu- larly observed, that either the rotary motion of the ball, or the action of its curved surface in sliding, would tend to force the centre of the ball out of the indentation in the same manner, as it is easily to be perceived that the centre would describe the same curve, if it were to roll or to slide. - It is moreover evident, that this power of turning the ball from its direction, would be added to that derived immediately from the obliquity of the side, though this would be the cause of it all, or, in other words, the effect would be different (what- ever was the hardness of the side) from what it would be if the ball were a mere point or flat body, acting against another ſlat oblique surface or indentation. - Case 3. If the force should be so great that the ball entirely buried itself, there would even then be two circumstances in favour of this construction; first, that the ball would have to perforate through a greater substance than if the side were perpendicular to the motion, the distance of which is shewn at H B fig. 1, and the oblique distance shewn at H O ; and Secondly, because the change of motion which would take place before the ball was quite buried, (as above described,) would still farther increase the length of substance to be per- forated by it, and the course of the ball might be so much changed, that it should (after it was quite sunk) have to per- forate the side through the remainder of its length upwards, instead of through its direct thickness. It would be possible, however, for the balls to come in a perpendicular direction to the side, and to go through it directly, but it is improbable that this should frequently be the case; and it seems that it would be less likely to happen if it were fired at from a short distance, than from a great one, as then only a moderate elevation of the guns would be re- quired, whereas, when the distance was small, the elevation would become so great, that it would be extremely difficult to take an aim so that the balls should come down upon it. ... Neither of the cases, however, would altogether exist as described; but, as all substances possess a certain degree of hardness and elasticity, there would be a mixed effect pro- duced, though I do not conceive the elasticity of wood to be sufficiently great to alter, the cases materially; the results would therefore, it appears, be nearly as stated when the elas- ticity was not supposed to exist, but with some very sensible difference. Since having made the preceding observations, I have tried the experiments relative to them on a small scale, and have found them precisely according to my ideas. The side, fig 1, was represented by a deal board, three-eighths of an inch thick, the return part W was of plate-iron, and the inside of the board ST was (perhaps improperly) coated with iron, the bullets were of lead, and about one-third part of the weight of a musket ball, and they were fired from a blunderbuss well charged; they made very slight long dents, not onc-eighth inch deep in the deal, and when the additional board T S was not used, they flew upwards, and perforated the iron return part W.; but when the board T S was added, they each made a dent also, near the narrow part I, and followed the return part W.; and then they returned against a deal board placed behind the stock of the blunderbuss, and left moderately deep impressions on it. I also made experiments on the plan of figs. 3, 4, and 5, though on a still smaller scale, and on a deal model, but with the same accordant results to the remarks I have made. A thin coating of iron, on a wooden side, would not, I presume, be advantageous, as the iron would bend away from that part of the ball with which it should be in absolute con- tact, and the ball would then be improperly directed : there- fore, whatever substance is employed, it should be of such a nature as to fit the ball as it goes, and the grain of the wood of which the side, &c. is made, should be in the direction of the motion of the ball, not transverse. It is scarcely necessary to notice, that if the object of return- ing the ball be dispensed with, the side may simply be formed into a triangle COP, figs. 3, 4, and 5, without the concave part NW AL; and, in fig. 1, without the return part W, and board TS, though the balls would be thrown more into the rigging by this means. . . . - The lower part L should, perhaps, rather bend upwards, to cause the balls to fly a little upwards in returning, because those which come against the side H, figs. 3, 4, and 5, will not only be lowered the whole distance between H and L, but as they will return rather more slowly than they came, they will also be attracted downwards with more force by the power of gravity. The curve will likewise be more effective, if made smaller at the entry NL, than at the other part WA. I have 382 F.O.U. F. O. U. DICTIONARY OF MECHANICAL SCIENCE. also to add, that a coating of grease on the side, &c. is, it seems, of service. - • * But, I am fully aware, that however the experiments might have succeeded in miniature, the great force of a cannon-ball might defy them all, though it is known that slight obstructions affect their motion, when opposed to them obliquely. It also remains to be further tried, whether the balls would be re- turned with sufficient force. Any person repeating these experiments, should (in order to avoid danger) stand at the side of the gun, at a great distance, and tie a string to the trigger, and of course must not place himself either behind or before it. These observations are meant also to apply to fortifications, where, it seems, that the plan would be as effectual, or more so, than for ships. - FORTIN, FoRt.Ret, or Field Fort, a sconce or little fort, whose flanked angles are generally distant from one another 120 fathoms. - FOSS, in Fortification, a hollow place, commonly full of water, lying between the scarp and counterscarp, below the rampart; and turning round a fortified place, or a post that is to be defended. Foss Way, one of the four principal highways of England, that anciently led through the kingdom, supposed to be made by the Romans, having a ditch upon one side. FOSSIL, in Natural History, any thing dug out of the earth; and therefore fossils may be native or extraneous: the former shew no traces of organization; the latter are the remains of the vege- table and animal kingdoms ; and these fossils are bones, shells, trees, leaves, &c. Numerous opinions are entertained of these organic remains; some authors maintaining that they are real stones, and stone plants, or bones; others, that they have been buried where they are now found, at the universal deluge. This seems the most natural opinion; for, in the tremendous convulsion of the whole mass of earth at the deluge, there is great reason to suppose that the various strata would range themselves according to their specific gravity, and bury in one general intermixture, earths, rocks, plants, quadrupeds, fishes, birds, and preserve them as we now find them, or at least give them those impressions they retain. FOTHERING, a peculiar method of endeavouring to stop a leak in the bottom of a ship, while she is afloat either at sea or at anchor, which is performed by fastening a sail at the four corners, letting it down under the ship's bottom, and then putting a quantity of chopped rope yarn, oakum, wool, cotton, &c. between it and the ship's side; by repeating the latter part of this operation several times, the leak generally sucks in a portion of the loose stuff, and thereby becomes partly and sometimes wholly stopped. Some persons prefer thrumming the sail, instead of letting down the loose stuff, but in this mode the sail is soon chafed through by the hole, if the leak is considerable, without affording sufficient substance to stop it. FOUL, a sea phrase, that is used in distinction to clear, and implies entangled, embarrassed. Hence, Foul Anchor, when the cable is twisted round the stock and flukes. Foul Bottom, when a bay is covered with weeds, grass, shells, filth, and rocks. Fowl Hawse, means that the cables are turned round each other, by the ship having swung the wrong way when moored. Foul Rope, a rope entangled and unfit for immediate use. Foul Water, is water troubled and rendered turbid by the ship's bottom rubbing on the ground. Foul Wind, is used to express that the wind is unfavourable, or contrary to the ship's course, as opposed to large or fair. FOUNDATION, in Architecture, is that part of a building which is under ground, and which Palladio makes as deep as one-fourth part the height of the whole building, unless there be cellars, when it may be somewhat lower. . Found ATION, in ecclesiastical or political matters, is a dona- tion or legacy in money or lands, for the maintenance or sup- port of some charitable institution, as a hospital, a school, &c. FOUNDER, To, to sink or go down. The fatal situation of a ship which is no longer able to keep above water, through accident, or the violence and continuation of a storm and the excess of the leaks, that fill her with water. Founder, an artist who casts metals in various forms, for different uses, as guns, bells, statues, printing characters, &c. shillings and the largest about 2s. 2d. per lb. FOUNDRY, the place or art of casting all sorts of metals, as, a bell foundry, type foundry, &c. In casting types or letters, the two things principally to be regarded, are the matter and the matrices. The matter is a compound metal, partly copper, and partly lead, mixed in a certain proportion, which every letter-founder regulates at his own discretion, to this he adds a quantity of other metal, to render the composition harder. The matrices of the letters are pieces of copper about 1% inch long, on which the impression of the intended eharacter has been cut, or struck by puncheons, &c. graven in relievo. Each letter has its proper matrix: there are particular ones for points, figures, rules, head-pieces, and othér ornaments of printing; the quadrats, being only of lead, and not intended to leave any impression, are cast in moulds without matrices; each matrice has its puncheon of steel, well-tempered. The matrices being struck, are put each at the end of an iron mould enclosed between two thin pieces of boards, three inches square; the two upper angles being cut off, so as to compose an irre- regular hexagon. Every thing belonging to the mould being disposed, the workmen begin to prepare the matter. The furnace, whereon the bason is placed for the metal to be melted in, is made of the same materials as crucibles. Over the furnace is placed the melting bason, or copper; divided into two equal parts, by a perpendicular partition, to melt either hard or soft metal. In this bason they melt only the matter already pre- pared ; that is, the mixture or composition made in the cruci- bles. A small iron ladle serves to skim off from the melted metal the impurities, which are melted over again. Two workmen are employed at each furnace; they have a table on which they lay the characters as soon as they are cast; to run the metal into the mould, the founder holds in his ladle just enough for one letter. Having filled this ladle, he pours the metal through a funnel, into the matrix or character. He then opens the mould, and takes out the character; and without loss of time shuts it again, replaces the matrix, and casts a new letter. It is incredible with what expedition all this is done. The letter being cast, the workman views it before he breaks off the jet, to see whether it be perfect, otherwise he throws it among the refuse of the fount. * When the letters are composed, they remain to be justified, which is a very delicate operation, that embraces their being polished and squared by boys, and finished by the most expert workmen in the buisness. But it would exceed our limits to enter upon all the stages of this complicated operation here. The excellence of types consists not only in the due per- formance of all the operations connected with their manufacture, but also in the hardness of the metal, the form and fine propor- tion of the character, and in the exact bearing and ranging of the letters in relation to one another. The smallest types are cast from an alloy of 25 parts of the regulus of antimony, and 76 of lead; the larger, 15 of antimony, and 85 of lead. There are about twenty different sizes of types in general use, all of which are cast in moulds and matrices, besides several larger sorts, which are cast from patterns in sand. The following table gives the designation of the twenty sizes alluded to, and the spaces they occupy in printing. They are sold to the printers by the pound ; the smallest being about 13 Lines to each Foot. Lines to each Foot. & Diamond type contains. . 204 |Great Primer contains .. 51 Pearl, . . . . . . . . . . . . . . . . . . 178 |Paragon, . . . . . . . . . . . . . . Nonpareil, ... . . . . . . . . . . . 143 |Double Pica, ...... . . . . . 4.1% Minion,. . . . . . . . . . . . . . . . 128 12 line Pica, ...... . . . . . . . 35% Brevier, . . . . . . . tº e º 'o e e º 'º e 1123 |2 line English, . . . . . . . . . . 82 Bourgeois, ... . . . . © e s e º 'º e 102 |2 line Great Primer,..... 25% Long Primer, . . . . . . . . . . . 89 2 line Double Pica, ... . . . 20% Small Pica, ............ 83 Canons,. . . . . . . . . . . . . . . . 18 Pica, . . . . . . . e c e º e º e s tº e e 71} |4 line Pica, . . . . . . . . . . . . 173. English,... . . . . . . . . . . ... 64 lá line Pica,... . . . . . . . ... 14% By the common method of type founding, only a single letter is cast at a time, and the operation has been nearly the same for seventy years. A scheme was however set on foot about seventeen years ago, to enable the founder to cast a great number of letters at one time, thirty, or more, but it was not carried into practice by any of the founders. About the same time, Monsieur Didot, assisted by Mr. Donkin, the engineer, F O Ú. F O U 333 DICTIONARY OF MECHANICAL SCIENCE, constructed a machine for a similar: púrpose; which was also intended to perform all the operations of the work, by the assistance of a boy only. - The invention which we have now to describe, is an improve- ment by Didot, upon his former highly ingenious machine, now rendered capable of casting 200 types at once, and to repeat || the operation, two or three times in a minute. A patent for this country has been taken out by Mr. J. L. Pouchée, who : established a type foundry in Little Queen-street, Holborn, where the machinery was for some time in full and successful operation. . . - The number of drawings which accompany the specification of . this patent obliges us to select such portions only as may best give a just idea of its construction, and we have for the same reason; thrown the side views into perspective, which exhibits the machine entire, as at fig. 1. Fig 2 represents one side of the mould separated into its component parts. Fig. 3 is a sec- tion of the several bars, composing both sides of the mould. , - Fig. 1. iſ: - __ ºf , dº º iſſºu:#”. ºf EWºlºſſºs . w Šs ‘. S , ſº §: t E N ** - - S. #ºſſ . |* P_-- Hº Erxº~fºs tº sº º º § T -º-Tº &Eſº ºl, Z. £ - y /. - .3% \;= =N* Fig. 4, exhibits a plan of Fig. 4. the same, fitted into, and encompassed by a frame of iron, a horizontal, and per- spective view of which is given at fig. 1. The same letters refer to the same parts in each of the figures. a fig. 3, is a steel bar, with horizontal grooves, in which are formed the bodies. e of the types; b b is the bar which holds the matrices ce, each of which is ar- ranged opposite to its re-. §º spective groove in the bar a, to which it, is screwed fast; the bar d is then screwed down to the bar, b, - which holds, the matrices ec firmly in their places. The bar e is next laid upon the bar a, which covers the grooves, and forms the upper sides of the square recesses, shewn also at e e, fig. 4;-f is the break-bar, and is placed in front of the bar a . a series of small nicks or openings are made in this bar, through which the fluid metal passes, into the grooves and matrices, 85. equal parts, and then form your scalc. where the bódy and letter of the type is cast; the grooves are closed by the spaces between the nicks of the break-bar coming against them and forming the feet of the types. The bar g is laid upon the break-bar as a cover to it, and the whole six bars thus: combined form one side, or one half of a pair of moulds, shewn in section, fig. 3. This section likewise exhibits the form of the apertures through which the fluid metal has to pass into the grooves and matrices; h is a receptacle between the moulds for the fluid metal, previous to its being forced into the moulds, as we shall presently discribe. In preparing the moulds for casting, the several bars com- posing them are connected together as before mentioned, and, laid upon a solid metallic bed upon the table k h, as shewn at fig. 4; the sides, of the iron frame l l, which turn upon joints, are then brought to bear sideways against the moulds; the top piece m, which also turns upon a joint, is brought down over the mould bars, which it firmly secures, by bringing the looped part of the swinging lever n shewn at fig. 1, over the end of the top piece m; which is effected by the aid of the hand lever p, forcing the tongue o against the lower end of the swinging lever, when the latch 2 falls and makes all fast. Thus pre- pared, a sufficient quantity of the fluid metal is poured out of a ladle into the receptacle between the moulds; a trigger at r is then pulled, when a string connected to it draws back a bolt or catch, s, which supports the long lever t, and allows it to fail with the rammer q into the receptacle, which drives with con- siderable force the fluid metal from thence into the moulds and matrices. On each side of the rammer q are fixed a guard or housing, to prevent the liquid metal from being splashed over the operator. In order to withdraw the types from the moulds, the workman places his foot upon the step u, when the compound lever v acts upon the pin w, under the leg ar, and forces out the rammer from between the moulds, which is then lifted up by the workman until it has passed the catch s, which supports it in the positions shewn in the figure. The mould is then opened, by throwing up the hasp z ; the swinging lever n then releases the end of the top piece, and allows the frame to be opened, and the moulds to be removed to a table, where the bars which compose it are placed under cramps, and sepa- | rated by means of wrenches: the types are them removed, and | undergo the operations of dressing, &c. as mentioned in the early part of our subject.—Register of the Arts. Bell Found RY. The metal of which beils are made is com- posed of three parts of copper and one of tin. The modern proportions for bells are to make the diameter fifteen times the thickness of the brim, and the height twelve times. The parts of a bell are: 1. The sounding bow, terminated by an inferior circle, which grows thinner and thinner. 2. The briin, or that | part of a bell whereon the clapper strikes, and which is thicker than the rest. 3. The outward sinking of the middle of the bell, or the point under which it grows wider to the brim. 4. the waist, or furniture, and the part that grows wider and | thicker quite to the brim. 5. The upper vase, or that part which is above the waist. 6. The pallet, which supports the stopper of the clapper within. 7. The bent and hollowed branches of metal uniting with the cannons, to receive the iron keys, whereby the bell is hung up to the beam, which is its support and counterpoise when rung out. In bell casting there are three processes: 1. The proportioning of the bell. 2. Forming the mould. 3. Melting the metal. The proportions of a bell are either simple or relative, the former gives it sonorosity, the latter establishes a requisite harmony between several bells. The method of forming the profile of a bell, in which the pro- portion of the several parts are seen, is this:—The brim, C I, | in the following figure, is the foundation of all the other nea- sures, and is divided into three equal parts. Draw the line H D, which represents the diameter of the bell. Bisect it in F, and erect the perpendicular Ff. Bisect D F and H F in E and G, at which draw perpendiculars Ee and Go., G E will be the diameter of the top or upper vase, i. e. the diameter of the top will be half that of the bell; and it will therefore be the diameter of a bell that will sound an octave to the other. Divide the diameter of the bell, or the line H D, into 15 equal parts, and one of them will give C 1 the thickness of the brim. Divide again each of these 15 equal parts into three other From this scale take 4 Q 334 F () U F O. W. DICTIONARY of MECHANICAL science. 12 of the larger divisions, or # of the whole scale in your com- passes, and setting one leg in D, describe an arc to cut the fine Ee in N ; draw N D, and divide this line into twelve equal parts; at the point l erect the perpendicular 1 C = 16, and C 1 will be the thickness of the brim = # of the diame- ter. Draw the line CD, bisect DN, and at the point of & el * @ // N - º: -- bisection erect the perpendicular 6 K = 1% of the larger divi- sions on the scale. With an extent of compasses = 30 brims, (or twice the length of the scale,) setting one foot in N, describe an arc of a circle, and with the same leg in K, and the same opening, describe another arc to intersect the former. On this point of intersection as a centre, and with a radius:= 30 brims, describe the arc NK; in 6 K produced, take KB = } of the larger measure of the scale, or 3 of the brim, and on the same centre with the radius of 30+ brims, describe an arc A parallel to N K. For the arc BC take 12 divisions of the scale, or 12 brims in the compass; find a centre, and from that centre, with this opening, describe the arc BC in the same manner as you did A B or N K. There are various ways of describing the arc Kp ; some bell founders describe it on a centre at the distance of 9 brims from the points p and K; others, as we have done in the figure, on a centre at the distance only of 7 brims from those points. . But it is necessary first to find the point p, and to determine the rounding of the bell p 1. For this purpose, on the point C as a centre, and with the radius C 1, describe the arc 1 p n. Bisect the part 1, 2 of the line D m, and erecting the perpendicular p m, this perpendicu- lar will cut the arc 1 p n in m, which terminates the rounding 1 p. Some founders make the bendings K a third of a brim lower than the middle of the line D N ; others make the part C ID more acute, and instead of making C 1 perpendicular to D N at 1, draw it ºth of a brim higher, making it still = 1 brim; so that the line 1 D is longer than the brim C 1. In order to trace out the top part N a, take in the compasses eight divisions of the scale, or 8 brims, and on the points N and I) as centers, describe arcs to intersect each other in 8; on this point 8, with a radius of 8 brims, describe the arc N b. This will be the exte- rior curve of the top or crown. and with a radius = 7# brims, describe the arc A. e, and this will be the interior curve of the crown, and its whole thickness will be 4 of the brim. As the point 8 does not fall in the axis of the bell, a centre M may be found in the axis, by describing with the interval of 8 brims on the centres D and H, arcs which will intersect in M ; and this point may be made the centre of the inner and outer curves of the crown, as before. The thick- ness of the cap which strengthens the crown at Q, is about $ of the thickness of the brim, and the hollow branches or ears, about ºth the diameter of the bell. The height of the bell in proportion to its diameter, is as 12 to 15, or in the proportion of the fundamental sound to its third major, whence it follows, that the sound of a bell is principally composed of the round of its extremity, or brim, as a fundamental of the sound of the crown, which is an octave to it, and of that of the height, which is a third. The particulars of moulding and casting are to be best learned in the workshop; as the former is either simple or complicated, according to the inscriptions, coats of arms, &c. designed to be put on the bell. . FOUNT, or Font, among Printers, &c. a set of types, sorted for use, that includes running letters, large and small capitals. single letters, double letters, points, commas, lines, numerals, &c. as a fount of English, of Pica, Bourgeois, &c. A fount of 100,000 characters, which is a common fount, would consist of 5000 types of a, 3000 of c, 11,000 of e, 6000 of i, 3000 of m, and about 80 or 40 of k, x, y, and z. But this is only to be under- On the same point 8 as a centre, stood of the lower-case types; those of the upper case having other proportions, which we need not here enumerate. Also a fount of 10 sheets would print 80 pages of this Dictionary without distributing a single letter, and it would weigh 120 lbs. per sheet, or 1200 lbs. in all, which at 2s. 6d. per lb. would amount to £150. 0s. 0d. Now, if there were two dozen founts in an office, the reader may form some idea of the capital necessary to carry on a large business in printing, including | presses, and all the numerous expenses contingent on thi | most popular and most useful profession. - FOUNTAIN, or ARTIFICIAL Fount AIN, in Hydraulics, a machine or contrivance by which water is violently spouted or darted up; called also a Jet d'Eau. There are various kinds of artificial fountains, but all formed by a pressure of one sort or another upon the water; viz. either the pressure or weight of | a head of water, or the pressure arising from the spring and elasticity of the air, &c. When these are formed by the pres: sure of a head of water, or any other fluid of the same kind with the fountain, or jet, then will this spout up nearly to the same height as that head, abating only a little for the resist- ance of the air, with that of the adjutage, &c. in the fluid rush- ing through; but, when the fountain is produced by any other force than the pressure of a column of the same fluid with itself, it will rise to such a height as is nearly equal to the alti- tude of a column of the same fluid, whose pressure is equal to the given force that produces the fountain. - Circulating Fount AIN, or Fountain of Hero of Alexandria, so called because it was contrived by him, is represented thus :— The air being only compressed by the concealed fall of water, makes a jet, which, after some continuance, is considered, by those who are unacquainted with the principle, as a perpetual motion, because they imagine that the same water which fell from the jet rises again. The boxes C E and DY X, being close, we see only the bason A B W, with a hole at W, into which the water spouting at B falls; but that water does not come up again; for it runs down through the pipe W X into the box D Y X, from which it drives out the air, through the ascending pipe Y Z, into the cavity of the box C E, where, pressing upon the water that is in it, it forces it out through the spouting pipe O B, as long as there is any water in C E ; so that this will play no longer than whilst the water contained in CE, having spouted out, falls down through the pipe W X into the cavity D Y X. The force of the jet is propor- tional to the height of the pipe WX, or of the boxes C E and D Y above one another: the height of the water, measured from the bason A B W to the surface of the water in the lower box D Y X, is always equal to the height measured from the top of the jet to the surface of the water in the middle cavity at C E. See the article Jet D’EAU, in which this subject is fully handled. . - FOURTEENTH, in Music, the octave, or replicate, of the seventh. A distance comprehending thirteen diatonic intervals. FOURTH, in Music, a distance comprising three diatonic intervals, or two tones and a half. t FOWLING, the art of taking or killing birds. It is either practised as an amusement by persons of rank and property, and then principally consists in killing them with a fowling piece, and the diversion is secured to them by the game laws; or it is practised for a livelihood, by persons who use nets and other apparatus. Fowling was formerly used for the pursuing and taking birds with hawks, more properly called Falconry. Fowling Piece, a light gun for shooting birds. That piece is always reckoned best which has the longest barrel, from 33 to 6 feet, with a moderate bore; though every fowler should have them of different sizes, suitable to the game he designs to kill. The barrel should be well polished and smooth within, and the bore of an equal bigness from one end to the other. which may be proved by putting in a piece of pasteboard, cut of the exact roundness of the top ; for if this goes down with- out stops or slipping, you may conclude the bore good. F. R. A F R. A. 335 DICTIONARY OF MECHANICAL SCIENCE, FRACTION is a part or parts of the unit, and written with two figures, with a line between them, as 4, 5, #, &c. The figure above the line is called the numerator, and the under one the denominater; which shews how many parts the unit is divided into ; and the numerator shews how many of those parts are meant by the fraction. There are four sorts of Vulgar Fractions; proper, improper, simple, compound and mixed, viz. - - • A Proper FRAction, is when the numerator is less than the denominator, as ?, ?, #, #, #, &c. • An Improper FRAction, is when the numerator is equal to, or greater than the denominator, as 3, #, #, '', &c. . Å Simple FRAction, is that which consists of a single nume- rator, and single denominator; and is either proper, or impro- per, as #, \, \}, &c. º tº a tº A Compound FRAction, is a fraction consisting of two or more other fractions connected by the word of; thus 3 of #, or 3 of ºr of 3, &c. are compound fractions. e A Complex FRAction, is that whose numerator and denomi- nator are both fractions; thus # is a complex fraction. frequently made by authors on arithmetic, are certainly im- proper, the former indicating an operation in multiplication, and the latter an operation in division; it is, therefore, im- proper to apply to them the denomination of fractions. An integer and fraction together is called a mixed number, that is, 74, 9}, &c. are mixed numbers. . - - - - - - Reduction of FRACTIONs.-1. To reduce fractions to a com- mon denominator.—Rule 1. Multiply each numerator into all the denominators, except its own, for a new numerator; and all the denominators, for a common denominator. Or, 2. Mul- tiply the common denominator by the several given numera- tors separately, and divide the product by their several deno- minators; the quotients will be the new numerators. Example. Reduce 4 and 4 to a common denominator. . Ans. }}, and 33. wntim. 2d num. 2 × 7 = 14, 4 x 4 = 16, then 4 × 7 = 28 den. = #, and #. 2. To reduce a vulgar fraction to its lowest terms.—Rule. Find a common measure by dividing the lower term by the upper, and that divisor by the remainder following, till nothing remains; the last divisor is the common measure; then divide both parts of the fraction by the common measure, and the quotient will give the fraction required. If the common mea- sure happens to be 1, the fraction is already in its lowest term; and when a fraction hath ciphers at the right-hand, it may be abbreviated by cutting them off; as, #|}. Example. Reduce #4 to its lowest terms. 24)32(1 24 These two distinctions, though com. measure 8)24(3 then 8) # (= # Ans. - 24 3. To reduce a mixed number to an improper fraction.—Rule. Multiply the whole number by the denominator of the fraction, and to the product add the numerator for a new numerator, which place over the denominator. To express a whole num- ber fraction-ways, set one for the denominator given. - Example. Reduce 18; to an improper fraction. 18 × 7.+ 3 E 129, new numerator. 4. To reduce an improper fraction to its proper terms.— Rule. Divide the upper term by the lower. Example. Reduce 4 to its proper terms. I 129 -- 7 = 18}. 5. To reduce a compound fraction to a single one.—Rule. Multiply all the numerators for a new numerator, and all the denominators for a new denominator. Reduce the new frac- tion to its lowest terms by Rule 2. Example. Reduce 3 of 3 of 3 to a single fraction. ; 3. : 3 := % reduced to the lowest term = 3; Ans. 6. To reduce fractions of one denomination to the fraction of another, but greater, retaining the same value.—Rule. Reduce the given fraction to a compound one, by comparing it with all Ans. 39. Ans. 18}. the denominations between it and that denomination which you would reduce it to ; then reduce that compound fraction to a single one. . Example. Reduce # of a penny to the fraction of a pound. * . . . Ans. # of , of k = Tºp. 7. To reduce fractions of one denomination to the fraction of another, but less, retaining the same value.—Rule. Multiply the numerator by the parts contained in the several denominations between it and that you would reduce it to, for a new numera- tor, and place it over the given denominator. Reduce the new. fraction to its lowest terms. Example. Reduce tº of a pound to the fraction of a penny. 7 × 20 × 12 E 1680, # reduced to its lowest term E #. Ams. 8. To reduce fractions of one denomination to another of the same value, having the numerator given of the required frac- tion.—Rule. As the numerator of the given fraction is to its denominator, so is the numerator of the intended fraction to its denominator. Eacample. Reduce # to a fraction of the same value, whose numerator shall be 12. As 2 : 3 : : 12 : 18. Ans. #. 9. To reduce fractions of one denomination to another of the same value, having the denominator given of the fraction re- quired.—Rule. As the denominator of the given fraction is to its numerator, so is the denominator of the intended fraction to its numerator. Example. Reduce 3 to a fraction of the same value, whose denominator shall be 18. As 3 : 2 : : 18 : 12. Ans. #. 10. To reduce a mixed fraction to a single one.—Rule. When the numerator is the integral part, multiply it by the denomi- nator of the fractional part, adding in the numerator of the fractional part for a new numerator; then multiply the deno- minator of the fraction by the denominator of the fractional part for a new denominator. - 36# Example. Reduce 48 to a simple fraction. Ans. }}} E #. 36 x 3 + 2 = 110 numerator. 48 × 3 E 144 denominator. When the denominator is the integral part, multiply it by the denominator of the fractional part, adding in the numerator of the fractional part for a new denominator; then multiply the mumerator of the fraction by the denominator of the fractional part for a new numerator. 47 655 11. To find the proper quantity of a fraction in the known parts of an integer.—Rule. Multiply the numerator by the common parts of the integer, and divide by the denominator. Example. Reduce # of a pound sterling to its proper quan- tity. Here 3 × 20 = 60, and -- 4 - 15s. Ans. 12. To reduce any given quantity to the fraction of any greater denomination, retaining the same value.—Rule. Re- duce the given quantity to the lowest term mentioned for a numerator, under which set the integral part (reduced to the same term) for a denominator, and it will give the fraction required. - Example. Reduce 15s. to the fraction of a pound sterling.— Here 15s. are 15 parts of 20s. or # which reduced to the lowest, gives #6. Ans. w Addition of FRActions.—Rule. Reduce the given fractions to a common denominator, then add all the numerators together, under which place the common denominator. Example. Add # and # together. # + #E # E 13. Ans. * When the fractions are of several denominations, reduce them to their proper quantities, and add as before, Example. Add # of a pound to # of a shilling. Here #6. = # of 39 = } = 15s. 0d. A and #sh. = # of f = ′ = 0s. 10d. § Ans. £0.15s. 10d. Subtraction of FRActions.—Rule 1. Reduce the given frac- tions to a common denominator, then subtract the less nume- rator from the greater, and place the remainder over the com- mon denominator. 2. When the lower fraction is greater than the upper, subtract the numerator of the lower fraction from Example. Reduce to a simple fraction. Ans. 3% = 4. F. R. A. F. R. A. DICTIONARY OF MEGHis N.I.C.A.L. SGE ENTO E. the denominator, and to that difference add the upper ſnume- rator; carrying some to the unit's place; of the lower whole number. . . . . Example 1. From t take #. 3.37–21, 5& 4= 20, 21 — 20 = 1 numerator. 4 × 7 = 28 denominator Eºs Ans.” * , - . . . . Ans. 433. 2. From 53 take #. 3. From # take $, ºr Ans. #. 4. From # take 4 of #. Ams. #. When the fractions are of several denominations, reduce them to their proper quantities, and subtract as before. Ex. From # of a pound take # of a shilling. Ans, 14s. 8d. - - - -20s. 3 × 20 60 Here #8. of -º--→ = − = 15s. 0d. . . . . . - * # - 1. . 4 4 . Answer. * , 12 . 12. 36 #60. 14s., 3d, And 3 of # = * *: = + = 0 - Multiplication of FRACTIONs.—Rule. Prepare the given numbers, (if they require it,) by the rules of Reduction; then multiply the numerators together for a new numerator, and the denominators for a new denominator. When any number, -either whole or mixed, is multiplied by a fraction, the product will be always less than the multiplicand, in the same propor- tion as the multiplying fraction is less than the unit. . . " Ea:ample. Multiply § by 3. . . . - . Ans. 3 × 3 = 9 num. 4 x 5 = 20 den. = #. Division of FRACTIONs:–Rule. Prepare the given numbers, (if they require it,) by the rules of Reduction; then multiply the denominator of the divisor into the numerator of the divi- dend for a new numerator, and the numerator of the divisor into the denominator of the dividend for a new denominator. When any whole number is divided by a fraction less than unity, the quotient will be greater than the dividend: but if any fraction be divided by a whole number greater than unity, * * * * * * the quotient will be less than the dividend. Ea. Divide #, by 3.5 × 9 = 45 num. 3 × 20 = 60 den. # = }. The Rule of Three in FRActions.—Rule. When the three terms are properly reduced, proceed as in the Rule of Three in whole numbers... - Example 1. If # of a yard cost# of a £-what will # of a yard come to at that rate 2 -- Aus. # = 15s. -- ~ * # yd. : # £. :: # yd. :: # 6. - for 4 × 5 × 9 – 180 num. cºsmºs \ 45 / 15. and 3 × 8 × 10 = 240 den. or # X # = } #)#(\;. - Example,:2. If 48 men can build a wall in 243 days—how many men can do the same in 192 days? Thus 192', 97 . . 48 . 1 × 97 × 48 97 97 T: ; T : 1555. T.T. = 4 x 4 = Tă = 6; men, The Double Rule of Three in FRActions.—This is stated in the same manner as in common arithmetic. Example. If a carrier receive 2#6. for the carriage of 3 cwt. 150 miles—how much ought he to receive for the carriage of 7 to the heinousness of the offence. - | as proper to be attended to in all cases of this kind is this, that cwt. 3, qrs, for a journey of 50 miles - qrs. miles. £, - 150 21, .. 50. 1 × 21 × 50. 1 : 10 ” I 150 x 10 × 1 12. 1050 ... 63. 1 × 1050 x 62 441 £ s. d. 1 1500 2 12 x 1500 × 3 - 240 - 1 16 9 FRACTURE, in Surgery, the rupture of a bone, or a solu- tion of continuity in a bone, when it is crushed or broken by Thus an Ol some external cause. - - FRAENUM, in Anatomy, a term applied to some membra- nous ligaments of the body. 4. - '- FRAENUM Lingua, the ligament under the tongue, which some- times ties, it down too close to the bottom of the mouth, and then requires to be divided, to give this organ its proper motion: FRAGARIA, the Strawberry, a genus of the polygynia order, in the icosandria class of plants, and in the natural method ranking under the 35th order; senticosae, which all ject for the general biographer and historian. thrive; in any common garden soil, producing abundant crops annually without much trouble.... " FRAME. See SPINNING... . . . . . . . FRANCHISE, in Law; synonymous to liberty—“a royal privilege, or branch of the king's prerogative, subsisting in the hands of a subject,” say the expounders of the law. ... Fran- chises:may be vested in either natural persons or bodies politic; in one man, or in many; as of a county palatinate, a corpora- tion,’ &c., of which each individual has by right or prescription the freedom. Other franchises are to hold a court.leet, to have a manor or lordship, a bailiwick, fair, market, toll, &c., . . . FRANK Fee, in Law, signifies the same thing as holding lands and tenements in fee-simple. . . . . . . FRANK Pledge, in our Law, signifies a pledge, or surety for the behaviour of freemen. - . . . . . . . : FRANK, or Franc, an ancient coin of gold, or silver, current in France. The value of the goldfrank was somewhat more than that of the gold crown; the silver, frank, was a third of the gold one. Silver franks are now the current coin in France, and all accounts are kept in francs and centimes, according to the decimal system. There are 20 sols to a franc, and some- times sols “still appear in small accounts. It is usually said that 24 franks, or 480 sols, are equivalent to a pound sterling, but the real par is about 25 francs to a pound sterliug. . . . FRANKs, or Franking Letters, by which they are forwarded free of postage, is a privilege that has been enjoyed by mem- bers of parliament from the first institution of the post-office. A member of parliament can frank only ten letters a day, and receive fifteen, free of postage; each of which must weigh less than one ounce. It is felony to forge a frank. - FRANKINCENSE, is the product of the juniperus lycia. FRANKLIN, BeN3AMIN, a celebrated American philosopher and politician, was born at Boston, in New England, in the year 1706. He was author of several tracts on electricity and other branches of natural philosophy, and was the first who drew electricity from a thunder cloud. But his knowledge, however eminent as a philosopher, is eclipsed by his fame as a politician, in which latter character he forms an excellent sub- . - Dr. Franklin died April 17, 1790, being then in the 84th year of his age. . FRAPPING, the act of crossing and drawing together the several parts of a tackle, or other complication of ropes, which had already been strained to their utmost extent; in this sense, it exactly resembles the operation of bracing up a drum. The frapping increases tension, and consequently adds to the security acquired by the purchase; hence the catharpings are no other than the frappings to the shrouds. * FRAPPING of a Ship, the act of passing four or five turns of a cable-laid rope, round the hull or frame of a ship in the mid- dle, when it is apprehended that she is not strong enough to resist the violent efforts of the sea. This expedient is only made use of for very old ships, which their owners are willing to venture to sea as long as possible by insuring them deeply. FRAUD. All deceitful practices in defrauding, or endea- vouring to defraud, another of his own right, by means of some artful device, contrary to the plain rules of common honesty, are condemned by the common law, and punishable according The distinction laid down, in such impositions or deceits, where common prudence might guard persons from the offence, it is not indictable, but the party is left to his civil remedy; but where false weights, or measures are used, or false tokens produced, or such measures taken to defraud or deceive, as people cannot by any ordinary care or prudence be guarded against, there it is an offence indictable. Persons convicted of obtaining money or goods by false pretences, or sending threatening letters to extort money or goods, may be punished by fine and imprisonment, or by pillory, whipping, or transportation, 30 G. II. c. 24. FRAXINUS, the Ash, a genus of the dioecia order, in the polygamia class of plants, and in the natural method ranking under the 44th order sepiariae. There are four species, of which the most useful is the common ash. This tree flourishes best in groves, but grows very well in rich soil, in open fields. It bears transplanting and hopping. In Lancashire, they lop the tops of these trees to feed the cattle in autumn. ... The wood F R. E. F R E 337 DICTIONARY OF MECHANICAL SCIENCE. is hard and tough, and is much used to make the tools em- potash. The bark is used in tanning calf skin. - FREE BeNch, signifies that estate in copyhold which the wife, being espoused a virgin, has after the decease of her hus- band for her dower, according to the custom of the manor. FREEDOM of CoRPorAtion, the right of enjoying all the privileges and immunities that belong to it. The freedom of cities and corporations is regularly obtained by serving an apprenticeship; but it is also purchased with money, and sometimes conferred by way of compliment. FREEHOLD, Frank Tenement, is land or tenement which a man holds in fee-simple, fee-tail, or for term or life; and is of two kinds, in deed and in law, the first being real possession of land or tenement, in fee, fee-tail, or for life; the other, is the right a man has to such land or tenement before his entry, or seizure. * . - * - FREEING, the act of pumping, or otherwise throwing out the water which has leaked into a ship's bottom at sea, &c. FREESTONE, a whitish stone dug up in many parts of England, that works like alabaster, but is more hard and durable, being of excellent use in building, &c. FREEZE, or FRIeze, in Commerce, a coarse kind of woollen stuff or cloth, so called, as being freezed or naped on one side. FREEZING, CoNG eLATION, in Philosophy, the transforma- uon of a fluid body into a firm or solid mass, by the action of cold; in which latter sense the term is applied to water when it freezes into ice ; to metals when they resume their solid form after being melted by heat; or to glass, wax, pitch, tallow, &c. when they harden again after having been rendered fluid by heat. See CoNG eLATION and Ev A PORATION. The process of congelation is always attended with the emission of heat, as is found by experiments on the freezing of water, wax, spermaceti, &c.; for in such cases it is always found that a thermometer dipped into the fluid keeps con- tinually descending as this cools, till it arrives at a certain point, being the point of freezing, which is peculiar to each fluid, where it is rather stationary, and then rises for a little, while the congelation goes on, at the same time the bulk of the body is expanded. The prodigious power of expansion evinced by water in the act of freezing is nearly double that of the most powerful steam-engines, and exerted in so small a mass, seemingly by the force of cold, was thought a very material argument in favour of those who supposed that cold, like heat, is a positive substance. Dr. Black's discovery of latent heat, however, has afforded an easy and natural explication of this phenomenon. He has shewn that, in the act of congelation, water is not cooled more than it was before, but rather grows warmer: that as much heat is discharged, and passes from a latent to a sensible state, as, had it been applied to water, in a fluid state, would have heated it to 135°. In this process the expansion is occa- sioned by a great number of minute bubbles suddenly produced." Formerly these were supposed to be cold in the abstract; and to be so subtile, that insinuating themselves into the substance of the fluid, they augmented its bulk, at the same time that by impeding the motion of its particles upon each other, they changed it from a fluid to a solid. But these are only air extricated during the congelation; and to the extrication of this air we ascribe the prodigious expansive force exerted by freezing water. By what means does this air come to be extricated, and to take up more room than it naturally does in the fluid? Perhaps part of the heat, which is discharged from the freezing water, combines with the air in its unelastic state, and, by restoring its elasticity, gives it that extraordinary force, as is seen also in the case of air suddenly extricated in the explosion of gunpowder. The greatest degrees of heat which are known, have been produced by concentrating the solar rays with a mirror, or lens, or by supplying a blow-pipe with oxygen gas. A very great degree of cold is produced by mixing snow with certain salts. The best salt for this purpose is muriate of lime. If this be mixed with dry, light snow, and stirred well together, the cold produced will be so intense, as to freeze mercury in a few minutes. Salt and snow also produce a great degree of cold. Evaporation likewise produces cold. The method of making ,” - ice artificially in the East Indies, depends upon this principle. ployed in husbandry. The ashes of the wood afford good - bottom of which they strew with sugar-canes, or dried stems of The manufacturers at Benares dig pits in large open plains, the maize, or Indian corn. Upon this bed they place a number of unglazed pans, made of so porous an earth, that the water oozes through their substance. These pans are filled towards evening, in the winter season, with water which has been boiled, and are left in that situation till morning, when more or less ice is found in them, according to the temperature of the air; there being more formed in dry and warm weather, than in cloudy weather, though it may be colder to the human body. Every thing in this operation is calculated to produce cold by evaporation; the beds on which the pans are placed, suffer the air to have a free passage to their bottoms, and the pans constantly oozing out water to their external surface, are cooled by the evaporation of it. In Spain, they use a kind of earthen jars, called buxaros, the earth of which is so porous, being only half-baked, that the outside is kept moist by the water which filters through it; and, though placed in the sun, the water in the jar becomes as cold as ice. It is a common practice in China, to cool wine or other liquors by wrapping a wet cloth round the bottle, and hanging it up in the sun. The water in the cloth evaporates, and thus cold is produced. Ice may be produced at any time by the evaporation of ether. FReezing Miature, a preparation for the artificial congela- tion of water and other fluids. The first person who made experiments on freezing mixtures was Fahrenheit. But the subject was much more completely investigated by Mr. Walker, in a paper published in the Philosophical Transactions for 1795. Since that time several curious additions have been made by professor Lowitz, particularly the introduction of muriate of lime, which produces a very great degree of cold when mixed with snow; and the experiments of Lowitz have been lately repeated and extended by Mr. Walker. In the Philosophical Transac- tions for 1801, p. 135, is given a table, divided into classes; in the first rank of these classes of mixtures, Mr. Walker has not specified the temperature at which the materials were, previous to mixing; the reader being informed, in a paragraph which immediately follows the table, that it is immaterial, the result being the same as stated in the table, whatever may be the temperature of the materials at mixing. So that it is not requisite to specify the temperatures at which it was supposed to be necessary the materials should be, previous to mixing, in order to produce the effects stated. - Professor Leslie has lately discovered that porphyritic trap, pounded and dried, will absorb one-tenth part of its weight of moisture, and can hence be easily made to freeze the eighth part of its weight of water. In hot countries the powder wiłł after each process recover its power by drying in the sun. This curious and beautiful discovery of artificial congelation, will therefore produce ice in the tropical climes, or even at sea, with very little trouble, and no sort of risk or inconvenience. Thus we are convinced of the wonderful power of chemistry. This one discovery, which enables man in the hottest climate, even in the torrid zone, to compose artificially, and by such a simple process, the product of the frigid zones, is but a single instance, but it is sufficient to rank that noble science among one of the most important to man. Even in our every-day meals, our tea, our coffee, every process of cookery, of medi- cine, in short, almost all the operations of nature and art, are carried on by the means either of chemical, electric, or magnetic processes, with all of which we may become ac quainted in some degree. The annexed figure repre- sents a large air pump, for the purpose of freezing, on Leslie’s principle. It con- sists of a stout low frame, in which a good air pump is fixed, and on the plate are six receivers, each furnished with a broad glass saucer for holding sulphuric acid, or - pounded whinstone, and a small porous earthen cup for holding the water. The machine may be seen at Messrs. Harris's, the opticians, No. 50, High Holborn. 4 R 338 R R. E. F R E Diction ARY OF MECHANICAL SCIENCE. Leslie has lately discovered that parched oatmeal is even a more powerful absorbent than they whinstone; and with a stratum of oatmeal, about a foot diameter, and one inch deep, he froze a pound and a quarter of water, contained in a hemi- spherical porous cup. The meal is easily dried, and restored to its former use. - - - FREEzing Point, denotes the point or degree of cold, shewn by a mercurial thermometer, at which certain fluids begin to freeze, or, when frozen, at which they begin to thaw again. On Fahrenheit's thermometer this point is at + 32 for water, and at — 40 for quicksilver, these fluids freezing at those two points respectively. See TherMoMETER. FREEzing Rain, or Raining Ice, a very uncommon kind of shower, which fell in the west of England, in December, 1672, of which we have various accounts in the Philosophical Trans- actions. This rain, as soon as it touched any thing above ground, as a bough, &c. immediately settled into ice; and, by multiplying and enlarging of the icicles, broke all down with its weight. The rain that fell on the snow immediately froze into ice, without sinking in the snow at all. It made an incredible destruction of trees, beyond any thing recorded in history. “Had it concluded with some gust of wind, (says a gentleman on the spot,) it might have been of terrible consequence. I | weighed the sprig of an ash tree, of three-quarters of a pound, the ice on which weighed 16 pounds. Some were frightened with the noise in the air, till they discerned it was the clatter of icy boughs, dashed against each other.” This phenomenon, however, is not uncommon in a less degree, and depends wholly on the nice balance of temperatures in the rain, and atmosphere. Dr. Beale observes, that there was no consider- able frost observed on the ground during the whole; whence he concludes, that a frost may be very intense and dangerous on the top of some hills and plains; while in other places it keeps at two, three, or four feet distance above the ground, rivers, lakes, &c. and may wander about very furious in some "places, and remiss in others not far off. This frost was followed by glowing heats, and a wonderful forwardness of flowers and fruits. - FReeze, in Naval Architecture, ornamental painting or sculpture on the upper part of a ship's quarter, stern, or bow. It consists generally of armour, instruments of war, marine emblems, &c. upon between the owner and the merchant for the hire and use of a vessel. * * wº FREIGHT. The freight of a vessel is usually agreed on either at the rate of so much for the voyage, or by the month, or per ton. FREIGHTING, or Letting out Vessels on Freight or Hire, was once one of the principal branches of the trade of the Dutch. They were the carriers of all the nations of Europe, and their purveyors, notwithstanding that their country produced little or nothing, and that they were forced to have everything necessary for the building of a vessel from other countries. The principal laws relating to freighting are:—That if a whole vessel be hired, and the merchant, or person who hires it, does not give it its full load or burden, the master of the vessel cannot, with- out his consent, take in any other goods without accounting to him for freight. That, though the merchant do not load the full quantity of goods agreed on in the charter-party, yet he shall pay the whole freight; and if he load more, he shall pay for the excess. If a time be appointed by charter-party, and either the ship be not ready to take in, or the merchant to put on board, the parties are at liberty, with remedy by action for the detriment. " If part be on board, and some misfortune prevent the merchant’s lading the whole in time, the master may con- tract with another, and have freight as damage for the time longer than limited. On the other hand, if the vessel be ready, the merchant may ship the remainder of the goods aboard another, and recover damages against the first master or owners; therefore, by the marine law, chance, or other noto- rious necessity, will excuse the master, but he loses his freight till he breaks ground. But if the merchant be in fault, he must answer the damage, or be liable to maintain the crew ten days; and if after that, the full freight: if damage afterwards, it is the merchant's risk: but by the common law, while the goods are on board, the master must see them forthcoming. If goods are fully laded, and the ship has broken ground, but the merchant afterwards declines the adventure, and unlades again, by the maritime law the freight is due. . If a sét time be agreed on between the merchant and master to begin and end the voyage, it may not be altered by the supercargo without special commission; and if a master shall sail on his voyage after the time agreed on for his departure, and damage hap. pens afterwards, he shall make it good. If a ship be freighted from one port to another, thence to a third, &c. and so home to the port whence she first sailed, (commonly called a trading voyage,) the whole is one and the same voyage, if performed according to the charter-party. If the ship be freighted out and in, no freight is due till the voyage is performed; if, there- fore, the ship perish coming home, the whole freight is lost. The master may set ashore such goods as he finds in his vessel which were not notified to him, or take them at a higher rate than was agreed on for the rest. But if the master freight his ship, and afterwards secretly take in other goods, he loses his freight; and if any of the freighter's goods should, for the ship’s safety, be cast overboard, the rest shall not be subject to average, but the master must make it good. If a ship be stopped or detained in its course, either through the master's or merchant's default, the delinquent shall be accountable to the other. Thus, if the freighter load the ship with prohibited goods, he shall answer the freight contracted; but if the ship put into any other port than she is freighted to, the master shall answer damage to the merchant; but if foreed in by storm, enemy, or pirates, he must then sail to the stipu- lated port at his own costs. If the master be obliged to refit his vessel during his voyage, the merchant shall wait, or else pay the whole freight; if the vessel could not be refitted, the master is obliged to hire another immediately, otherwise only to be paid his freight in proportion to the part of the voyage performed; though, in case the merchant prove that the vessel, at the time it set sail, was not capable of the voyage, the master must lose his freight, and an account for damages to the merchant. Freight shall be paid for merchandises which the master was obliged to sell for victuals, or refitting, or other necessary occasions, paying for the goods at the rate the rest were sold at where they were landed. In case of a prohibition | of commerce with the country whither the vessel is bound, so FREIGHT of A SHIP, the hire of part thereof, usually paid for the carriage and conveyance of goods; or the sum agreed that it is obliged to be brought back again, the master only shall be paid freight for going. And if a ship be stopped or | detained in its voyage by an embargo by order of the prince, there shall neither be any freight paid for the time of the deten- tion in case it be hired per month, nor shall the freight be increased, if hired for the voyage; but the pay and the victuals of the sailors during the detention, shall be deemed average. ‘Freight is also used for the burden or lading of a ship, or the cargo of goods, &c. which she has on board. Freight is also a duty paid to the government of France by the masters of foreign vessels going in or out of the several ports of the kingdom. - It is to be observed, that all vessels not built in France are accounted foreign, though belonging to that government, and as such, are liable to the payment of an impost, unless otherwise exempted, or that two-thirds of the crew are French. The Dutch and the Hanse Towns were exempted from the duty of freight. FRENICLE, BERNARD, a celebrated French mathematician of the seventeenth century, contemporary and companion of Descartes, Fermet, Roberval, and the other distinguished mathematicians of that time. - FRESCO, a method of painting in relievo on walls, so as to endure the weather. It is performed with water colours on fresh plaster; or a wall laid with mortar not dry. This sort of painting has a great advantage, by its incorporating with the mortar with which it dries. FRESH, when applied to the wind, signifies strong, but not violent or dangerous; hence, when the gale increases, it is said to freshen. FReSh Shot, signifies the falling down of any great river into the sea, by means whereof the sea hath fresh water a good way from the mouth of the river. As this is more or less, they call . | it a great or small fresh shot. F R. I F R i 339 DictionARY of MechANICAL science , Fresh Spell, a fresh gang to relieve the rowers in the long- boat. FREsh Water; implies water fit to drink, in oppostion to sea or salt water. FRESH Way of a Ship implies considerable velocity. . . . . - . . To Fissues Hawse, to relieve that part of the Čable which has for some time been exposed to friction in one of the hawse- holes, when the ship rocks and pitches at anchor in a high sea; this is done by applying fresh service to the cable within board, and then veering it into the hawse. - . e FReshes, imply the impetuosity of an ebb-tide increasing by heavy rains and flowing out into the sea, which it often disco- lours to a considerable distance from the shore, insomuch as the line which divides the two colours may be perceived dis- tinctly for a great length along the coast. - FRET, or FRento, in Architecture, a kind of ornament, con- sisting of two lists or fillets interlaced, and running at parallel distances equal to the breadth. - FRET, in Music, a kind of stop on some instruments, parti- cularly bass-viols and lutes. - FRIABILITY, that quality of certain bodies whereby they are easily reduced to powder. Thus we speak of the friability of earths, &c. - FRICTION, the act of rubbing two bodies together, or the resistance in machines caused by the motion of the different parts against each other. Friction arises from the roughness or asperity of the surface of the body moved on, and that of the moving body; for such surfaces consisting alternately of small eminences and cavities, these act against each other, and prevent the free motion that would ensue, on a supposition of the two bodies being perfectly polished planes. Mr. Ferguson found that the quantity, of friction was always proportional to the weight of the rubbing body, and not to the quantity of surface; and that it increased with an increase of velocity, but was not proportional to the augmentation of celerity. He found also that the friction of smooth soft wood, moving upon smooth soft wood, was equal to one-third of the weight; of rough wood upon rough wood, one-half of the weight: of soft wood upon hard, or hard upon soft, one-fifth of the weight; of polished steel upon polished steel or pewter, one-quarter of the weight; of polished steel upon copper, one- fifth; and of polished steel upon brass, one-sixth of the weight. - Columb has made numerous experiments upon friction, and by employing large bodies and ponderous weights, and con- ducting his experiments on a large scale, he has corrected several errors which necessarily arose from the limited ex- periments of preceding writers; he has brought to light many new and striking phenomena, and confirmed others which were hitherto but partially established. We cannot in a work of this kind follow M. Columb through his numerous and varied experiments; all that can be ex- pected will be a short abstract of the most interesting of his results; a few of which are as follow : — 1. The friction of homogeneous bodies, or bodies of the same kind moving upon each other, is generally supposed to be greater than that of heterogeneous bodies; but Columb has shewn that there are exceptions to this rule. 2. It was generally supposed that in the case of wood, the friction is greatest when the bodies are drawn contrary to the course of their fibres; but Columb has shewn that the friction in this case is sometimes the smallest. 3. The longer the rubbing surfaces remain in contact, the greater is their friction. 4. Friction is in general proportional to the force with which the rubbing surfaces are pressed together, and is commonly equal to between one-half and one-quarter of that force. 5. Friction is not generally increased by augment- ing the rubbing surfaces. 6. Friction is not increased by an increase of velocity, at least it is not generally so; and even in some cases the friction decreases with an increase of cele- rity. 7. The friction of cylinders rolling upon an horizontal plane is in the direct ratio of their weights, and in the inverse ratio of their diameters. From a variety of experiments on the friction of the axes of pulleys, Columb also obtained the following results;–When an iron axle moved in a brass bush or bed, the friction was one-sixth of the pressure; but when the bush was besmeared with very clean tallow, the friction was only one-eleventh; when properly applied, makes the friction two-thirds less. swine's grease was interposed, the friction amounted to 5.5% and when olive-oil was employed as an unguent, the friction was never less than $, or 7-5. oak, and the bush of guaiacum-wood, the friction was 3, when tallow was interposed; but when the tallow was removed, so that, a small quantity of grease only covered the surface, the friction was increased to it. When the bush was made of elm, the friction was of similar circumstances º and ºn which is the least of all. If the axis be made of box, and the bush of guaia- cum-wood, the friction was 3, and ſº, circumstances being the same as before. If the axle be of box wood, and the bush of elm, the friction will be # and ºn ; and if the axle be of iron, and the bush of elm, the friction will be h of the force of pres- sure. In wood rubbing upon wood, oil, grease, or black-lead, is. Wheel- naves, when greased, have only one-fourth of the friction they would have if wet. Hence the propriety of so contriving wheel naves as to keep the grease from being dissipated. When polished steel moves on steel, or pewter properly oiled, the friction is about one-fourth of the weight; on copper or lead, one-fifth ; on brass, one-sixth ; and metals have more friction when they move on metals of the same kind, than on different metals. The friction of a single lever is very little. The friction of the wheel and axle is in proportion to the weight, velocity, and diameter of the axle; the smaller the diameter of the axle, the less the friction. The friction of pulleys is great, on account of the smallness of their diameters in proportion to that of their axes ; because they often bear against the blocks, When the axis was of green and from the wearing of their holes and axles. In the wedge and screw there is much friction. Screws with sharp threads have more friction than those with square threads, and endless screws have most. - + An easy method of experimenting on the friction of surfaces, is, to place a plank with its upper surface level; and on this a thin block of the matter to be tried, with a cord fixed to it, which block may be loaded with different weights; and a spring steelyard attached to the other end of the cord, to draw it along by, will shew the force necessary to produce motion. See the following figure, where A A is the plank, B the block of matter to be tried loaded with a weight W, C the scale of the spring steelyard; which shews the force required to over-, come the friction, when the block B is moved by drawing at the hook D. By attending to a few precautions, the friction of surfaces may be easily ascertained with this simple apparatus. Thus, to try the friction of white deal on white deal, the plank A A was of that substance, as well as the block B. Then a º: " *— #. K- rºº, ºr—- * == fºur-aniºninuºulinuiºmutinº º "…º. ººº-ºº-ºº. . . . . ; ; *….: '. s s tº ... . . . . ." . . -º-, * : * : * , , § - a . . .”. – ' , "…º. . . * * * * * º, tºº, , , ..., x -º ºr *.*.*.* * ~ *-ºs -- . . . . . . . . . . . . . " : ºr . . . . . . ." . 2.” . .]:... . . " ' " ... * * * * * . . . . . . . . . * * * * > . . . . . . . . . . . . .s", . . . . . . . . . . . . . . . . . . . . . * ,s º: ... -- 2: ... . . . . . . . . . . . . . . . . ." . . . . . . . . . . . . . . . . ." ... weight W was put on the block, when the block and the load upon it amounted to 20 lbs. The force required to move it from rest, as shewn by the steelyard, was 7 lbs. ; and when there was 201bs, more weight laid upon the block, the force to move it was 14 lbs., hence we find that the friction increases in the same proportion as the weight. In making the experi- ment on the friction of wood, the block moves quickly forward as soon as you have gently drawn the spring to the measure of its friction at rest, and it may be continued in gentle motion with a less degree of force. Now, if you continue to draw steadily, so as to give the block the slowest regular motion it will take, the scale will shew the friction in motion to be 3% lbs. when 340 F : R I F. R. I DICTIONARY OF MECHANICAL SCIENCE: the load is 20 lbs., and 7 lbs. when the load is 40 lbs. ; therefore the friction in motion is not sensibly different from being pro- portional to the pressure. . . - . . - The relation between the friction and the pressure is—20 : 7 :+ 100 : 35; that is, the friction from rest is 35 lbs. when the prèssure is 100 lbs. or 35 per cent. in white fir on white fir, drawn in the direction of the grain of the wood, when the rub- bing surfaces of the fir have been planed true and even. And the friction of white fir on white fir, in motion, is, 40 : 7 :: 100 : 173, or 174 lbs. when the pressure is 100 lbs. that is, 173 per Cent. . . - - - .. - In trying the friction in motion, the slowest regular move- ment should be obtained. If you endeavour to produce a quicker motion, you will find that a greater force is necessary; because it requires more force to give a body a greater velocity than a small one, though the friction be the same. Without this, explanation, a very wrong measure of friction might be adoptcd. . - The friction from rest of white fir on white fir, across the grain, is not quite 33 lbs. when the pressure is 100 lbs.: but when in motion, the friction is sensibly different from that in the direction of the grain. - The surface of the block in the preceding trial was six square inches, and when it was reduced to three square inches, the same results were obtained. In these trials there was no attempt made to ascertain to what extent it was possible to reduce the rubbing surfaces without increasing the friction. To try the friction of metals at a small expense, let the blade a saw be laid flat on the plank A. A., and a small piece of metal, with one of its faces ground true, will serve for the moving piece B. If the moving piece B be of steel, the surfaces will then be steel on steel, and the friction from rest is sensibly the same as the friction in motion; i.e. 20 lbs. when the pressure was 100 lbs., or the friction one-fifth of the pressure. When the piece B was of cast iron, ground true and even, the friction was 22 lbs. when the surfaces were pressed together by 100 lbs. and it was sensibly the same at the first moving from rest, as to continue a slow motion. When the piece B was of gun- metal,” ground true and even, the friction was only 154 lbs. when the pressure was 100 lbs. and the same in slow motion as from rest. From these experiments it will appear, that the friction of different combinations of matter differ very considerably ; and that an immense quantity of power may be lost in a machine by using those substances for the rubbing parts which have great friction. We see that in a combination, where gun-metal moves against steel, the same weight may be moved with a force of 15% lbs., which it would require 22 lbs. to move when cast iron moves against steel. The resistance, called friction, performs important offices in nature and in works of art. Friction destroys, but never gene- rates motion. Were there no friction, all bodies on the surface of the earth would be clashing against one another: rivers would dash with unbounded velocity, and we should see little besides collision and motion. As it is, whenever a body acquires a great velocity, it soon loses it by friction against the surface of the earth; the friction of water against the surfaces it runs over, soon reduces the rapid torrent to a gentle stream; the fury of the tempest is lessened by the friction of the air on the face of the earth; and the violence of the ocean is subdued by the attrition of its own waters. Its offices in works of art are equally important. 4- Our garments owe their strength to friction; and the strength of ropes, sails, and various other things, depends on the same cause ; for they are made of short fibres, pressed together by twisting, and this pressure causes a sufficient degree of friction to prevent the fibres sliding one upon another. Without fric- tion, it would be impossible to make a rope of the fibres of hemp ; or a sheet of the fibres of flax; neither could the short fibres of cotton have ever been made into such an infinite variety of forms as they have received from the hands of our truly imgenious countrymen. Wool also has been converted into a thousand textures for comfort or for luxury, and all these are constituted of fibres, united by friction. In fine, if *--- * A composition of copper and tin used for bearings in machinery. friction retards the motion of machines, and consumes a large quantity of moving power, we have a full compensation in other, and equally necessary, benefits which it insures to us. FR1ction, in Medicine and Surgery, the act of rubbing the surface of the body, whether with the hand only, with the flesh- brush, flannel; or other substances, or with oils, ointments, of other medicinal matters, with a view, to the preservation of health, or to the removal of particular diseases. . In delicate habits the use of the flesh-brush, or gentle rubbing with the hand, until some degree of glow is produced on the surface of the skin, may contribute, like riding or other species of exercise, to support or improve the health. The wholesome effects of friction are well illustrated by the advantages of cur- rying horses; the benefits derived from it in these animals are generally considered as equivalent to half the feeding.—Fric- tion is an efficacious remedy in several conditions of disease ; particularly in chronic rheumatisms of long standing; in mus- cular contractions, succeeding to rheumatism, &c. and con- nected often with effusions of lymph; in some states of para- lysis; in certain indolent tumours, &c. In these cases, a variety of unguents, and liniments is recommended; but the friction itself is the principal source of relief. - FRIENDLY Societies, denote associations, chiefly among the most industrious of the lower and middling class of trades- men and mechanics, for the purpose of affording each other relief in sickness; and their widows and children some assistance at their death. These have been thought worthy of the protection of the legislature, to prevent frauds which had arisen from the irregular principles on which many of them were conducted. The statute 33 Geo. III. c. 54, provides, that any number of persons may form themselves into a society, and raise among themselves a fund for their mutual benefit, and make rules and impose fines. The rules, declaring the purpose for which such societies are established, are to be exhibited to the quarter sessions, who may annul or confirmi them; in which latter case, they are to be signed by the clerk of the peace. No rule thus confirmed is to be altered but at a general meeting of the society, and subject to the control of the sessions. . r - • FRIEZE, in Architecture, that part of the entablature of columns between the architrave and corniche. Anciently friezes were enriched with figures of animals; in moderh times, they are commonly ornamented by figures in basso relievo. FRIGATE, in the Navy, a light nimble ship, built for the purpose of sailing swiftly. These vessels mount from twenty to forty-four guns, and make excellent cruisers. - FRIGATE-built, the disposition of the decks of such merchant ships as have a descent of four or five steps from the quarter- deck and forecastle into the waist, in contradistinction to those whose decks are on a continued line for the whole length of the ship, which are called galley-built. Formerly the name of frigate was only known in the Mediterranean, and applied to a kind of long vessels navigated in that sea with sails and oars. The English were the first who appeared on the ocean with those ships, and equipped them for war as well as commerce. FRIGORIFIC PART1cLes, is a term used by some early philosophers to denote what they considered the matter of cold, as modern philosophers make caloric the matter of heat. FRINGELLA, in Ornithology, a genus belonging to the order of passeres, of which there are one hundred and three spe- cies, distinguished principally by varieties in their colour, as the carduelis, or goldfinch. 2. The caelebs, or chaffinch. 3. The montifringilla, or bramling. 4. The domestica, or sparrow. 5 The spinus, or siskin. In the bird-shops in London it is known by the name of the aberdavine. It is a docile species, and is often kept and paired with the canary-bird, with which it breeds freely. 6. The linota, or linnet. 7. The cannabina, or greater redpole, which frequents our sea-coasts, and is often taken near London. 8. The linaria, or lesser redpole, is known about London by the name of stone redpole. 9. The montium; or twite, about the size of a linnet. 10. The canaria, or canary- bird, originally peculiar to those islands, to which it owes its name. These birds are all well known. - : FRIT, in the Manufacture of Glass, is the matter or ingredi- ents of which the glass is to be made, when they have been F. R. U. F.U L 341 DICTIONARY OF MECHANICAL scIENCE. calcined or baked in a furnace; and these ingredients are soda. and sand or flint: FRITH, an ar Clyde, &c. : & - of the sea, as the frith of Forth, the frith of #Rizing, in the Woollen Manufactories, is a term applied * to the forming of the knap of cloth or stuff into any number of *... little hard burrs or prominences, covering almost the whole ground thereof. Some cloths are only frized on the back, as black cloths; others on the right side, as coloured and mixed cloths, rateens, bays, freezes, &c., Frizing may be performed two ways; one with the hand, that is, by two workmen, who con- duct a kind of plank that serves for a frizing instrument. The other way is by a mill, worked either by water or a horse, or sometimes by men. This latter is esteemed the better way of frizing, the motion being uniform and regular, and the little knobs of the frizing are formed more equably and regularly.— The structure of this useful machine is as follows: The three principal parts are, the frizer or crisper; the frizing-table; and the drawer, or beam. The two first are two equal planks, or boards, each about 10 feet long, and 15 inches broad; differ- ing only in this, that the frizing-table is lined or covered with a kind of coarse woollen stuff, of a rough, sturdy knap, and that the frizer is incrustated with a kind of cement composed of glue, gum-arabic, and yellow sand, with a little aqua vitae, or urine. The beam or drawer, thus called because it draws the stuff from between the frize and frizing-table, is a wooden roller, beset all over with little, fine; short points or ends of wire, like those of cards used in carding of wool. The disposi- | tion and use of the machine are thus; the table stands immove- able, and bears or sustains the cloth to be frized, which is laid with that side uppermost on which the knap is to be raised. Over the table is placed the frizer, at such a distance from it as to give room for the stuff to be passed between them; so that the frizer, having a very slow, semicircular motion, meeting the long hairs or knap of the cloth, twists and rolls them into little knobs or burs, while, at the same time, the drawer, which is continually turning, draws away the stuff from under the frizer, and winds it over its points. FROG-FISH of Surinam, a singular animal, which is pro- duced by the transformation of a frog into a fish. In Surinam these fishes are called jakies. They are cartilaginous, of a substance like our mustcla, and exquisite food. They are formed with regular vertebrae, and small bones all over the body, divided into equal parts; are first darkish, and then gray; their scales make a beautiful appearance. - FROST, such a state of the atmosphere as causes the con- gelation or freezing of water or other fluids into ice. In the more northern parts of the world, even solid bodies are affected by frost, though this is only or chiefly in consequence of the moisture they contain, which being frozen into ice, and so expanding, as, water is known to do when frozen, it bursts, and rends any thing in which it is contained, as plants, trees, stones, and large rocks. Many fluids expand by frost, as water, which expands about one-tenth part, for which reason ice floats in water; but others again contract, as quicksilver, and thence frozen quicksilver sinks in the fluid metal. Frost, being derived from the atmosphere, naturally proceeds from the upper parts of bodies downwards, as the water and the earth ; so the longer a frost is continued, the thicker the ice becomes upon the water, in ponds, and the deeper into the carth the ground is frozen. g FROTH SPIT, or Cuckow Spit, a name given to a white froth or spume very common in the spring. It forms the nidus of a species of cicada. - FRUCTIFICATION, the terminating of an old vegetable, and the beginning of a new successor. See BotANY. FRUIT, in Botany, is that part of a plant in which the seed is contained; and fruits are recent, fresh, and dry, according as they have been gathered for immediate use, or prepared for keeping, by being dried in the sun, or otherwise preserved. FRUIT Stones swallowed, have often been the cause of fatal complaints in the bowels; for though the guts are so defended by their proper mucus, that people, and children especially, seldom suffer by the generality of things they devour; yet the hair off the skins of animals, the stumps of birds’ feathers, the fibres, vessels, and nerves of plants, are not altered by the stomach, and often collect in lumps in the intestines, producing colics, pains, &c. without being voided, except by the most violent purges. • . : FRUSTUM, in Geometry, is the part of a solid next the base, left by cutting off the top or segment by a plane parallel to the base; as the frustum of a pyramid, of a come, of a conoid, of a spheroid, or of a sphere, which is any part comprised between two parallel circular sections; and the middle frustum of a sphere is that whose ends are equal circles, having the centres of the sphere in the middle of it, and equally distant from both ends. FUCUS, a name given by the ancients to certain dyes and paints. . By this name they called a purple sea-plant, used by them to dye woollen and linen cloths of that colour. The dye was very beautiful, but not lasting; for it soon began to change, and in time went wholly off. - FUCUs, in Botany, a genus of the order of algae, belonging to the cryptogamia class of plants; as, I. The serratus, serrated fucus, or sea-wrack, frequent upon the rocks at low-water- mark. 2. The vesiculosus, bladder fucus, common sea-wrack, or sea-ware, grows on the sea-rocks about low-water-mark. This species is an excellent manure for land; to which pur- pose it is often applied in Scotland, and other countries. But the most beneficial use to which the fucus vesiculosus is applied, is in making kelp, a work much practised in the Western isles. The manufacture or burning of kelp employs 30,000 per- sons in Great Britain, and it sells from £4. 10s. to £5.5s. a ton. FUEL, comprehends the fluid inflammable bodies; peat or turf; charcoal of wood; pit-coal charred ; and wood, or pit- coal in a crude state, and capable of yielding a copious and bright flame. - FUGUE; in Music, aterm derived from the Latin fuga, a flight, and signifying a composition either vocal or instrumental, or both, in which one party leads off some determined succession, of notes called the subject, which, after being answered in the fifth and eighth by the other parts, is interspersed through the movement, and distributed amid all the parts at the pleasure of the composer, sometimes accompanied by other adventitious matter, and sometimes by itself. There are distinct descrip- tions of fugues; the simple fugue, the double fugue, and counter fugue. FULCRUM, in Mechanics, the prop or support upon which a lever is sustained. See Lever. - FULGORA, or LANtern FLY, an insect belonging to the hemiptera order. 1. The Peruvian lantern-fly measures nearly three inches and a half from the front to the tail, and about five inches and a half from wing to wing, when expanded; this beau- tiful insect is a native of Surinam, and many other parts of South America, and during the night diffuses so strong a splen- dour from its head, that it may be employed for the purpose of a candle or torch ; and it is said, that three or four of the insects tied to the top of a stick, are frequently used by travel- lers for that purpose. 2. The fulgora candelaria is a smaller species than the preceding, and is a native of China. , 3. Fulgora diadema is an Indian species; its colour is brown, with red and yellow variegations; in size it is nearly similar to that of the preceding species. - - FULICA, the Gallinule and Coot, a genus of birds of the order of gallae, of which there are 25 species, 18 of which belong to the gallinule division, distinguished by having the toes fur- nished with broad scalloped membranes; and seven comprehend the coots, which have the toes divided to their origin. The atra, or common coot, has a bald forehead, a black body, and lobated toes, and is about 15 inches in length. They frequent lakes and still rivers; making their nests among the rushes; with grass, reeds, &c. floating on the water, so as to rise and fall with it. - . . . FULL AND BY, the situation of a ship with regard to the wind, when she is close-hauled, and sailing in such a manner as neither to steer too nigh the direction of the wind, nor to deviate from it; or it is when a ship is as close as she will lie to the wind without suffering the sails to shiver; hence, Keep her Full, is the order to the helmsman, not to incline too much to windward, and thereby shake the sails, which would retard the ship’s velocity. e . . - .* FULLER, a workman employed in the woollen manufac. 4 S DICTIONARY OF MECHANICAL SCIENCE. F.U.N. tories to mill or scour cloths, serges, and other stuffs, in order to render them more thick, compact, and durable. , | FULLER'S EARTH, a well-known mineral, generally of a greenish white colour, more or less mixed with brown, gray, or yellow; of a soft and friable texture, and somewhat unctuous to the touch. When thrown into water, it immediately absorbs Its great utility in it, and breaks down into a fine pulp. removing grease from woollen cloths, and other fabrics, has given this earth a great value in commerce, and its exportation is prohibited under very severe penalties. There are very extensive beds of this earth in several counties in England, as Kent, Surrey, Sussex, and at Wavedon, near Woborn, in Bed- fordshire. In no country in the world is such excellent fuller’s earth produced as at Wavedon. valuable property of this earth, of taking grease out of woollen and other cloths, which, on a large scale, is effected by the operation called fulling, whence its name has been derived. This, which is performed by a kind of water-mill, called a fulling-mill, is particularly necessary with respect to new cloths, for the purpose of depriving them of the grease and oil which has been used in their preparation. - - ', In the dressing of cloth, this earth is so indispensable, that foreigners, although they can procure the wool, are never able, without fuller's-earth, to reach the perfection of the English cloths; and in this country incalculable quantities of it are con- sumed. As an article of domestic utility, it might be more frequently used than it is for the cleaning and scouring of wooden floors and wainscots. In this respect it might be rendered an excellent substitute for soap. See WoolleN CLoths. - - FULLING, the act of cleansing, scouring, and pressing, stuffs, cloths, stockings, &c. to render them stronger, firmer, and closer; called also milling, because these cloths are in fact scoured by a water mill. The principal parts of a fulling-mill are, the wheel with its trundle, which gives motion to the tree or spindle, whose teeth communicate that motion to the pestles or stampers, which fall into troughs, wherein the cloth is put with fuller's earth to be scoured, and thickened by this process of beating it. - - FULMINATING Powder, (from fulmino, to thunder,) is a prepared powder which explodes upon the application of cer- tain degrees of heat, with instantaneous combustion and prodigious loud noise. • ‘ - ‘Simple fulminating powder, without any metallic substance, is thus prepared; take three parts of nitre, two of purified pearl- ash, and one of flowers of sulphur; mix the whole very accu- rately in an earthen mortar, and place it on a tile or plate before the fire till it is perfectly dry; then transfer it while hot into a ground stopper bottle, and it may be kept without injury for any length of time. In order to experience its effects, pour from ten to forty grains into an iron ladle, and place it over a slow fire; in a short time the powder becomes brown, and acquires “a pasty consistence; a blue lambent flame then appears on the surface, and in an instant after the whole ex- plodes with a stunning noise and a slight momentary flash. If the mass be removed from the fire as soon as it is fused, and kept in a dry well-closed vial, it may at any time be exploded by a spark, in which case it burns like gunpowder, but more rapidly and with greater detonation ; but this effect cannot be produced on the unmelted powder, how accurately soever the ingredients of it are mixed together. When fulminating pow- der is in fusion, but not heated to the degree necessary to produce the blue flame, a particle of ignited charcoal thrown upon it will occasion immediately a remarkably loud explosion. It appears, that the ingredients of this powder do not acquire their fulminating property till combined by fusion; in other words, till the potash of sulphur form sulphuret of potash; whence fulminating powder may also be made by mixing sul. phuret of potash with nitre, instead of by adding the sulphur and alkali separate. In all these, the cause of the detonation or fulmination is not accurately understood. In simple fulmi- nating powder, there is a very large portion of elastic gas evolved; in fulminating gold or silver, a much smaller; yet the explosion in the latter case is infinitely greater than that in the former. - - . .*ulminating Gold, Dissolve pure gold into muriatic acid to We have noticed the interest from revenues allotted for that purpose. saturation, and dilute the solution with three times its bulk of distilled water, and add to it gradually some pure ammonia';. a yellow precipitate will be obtained, which must be repeatedly washed with distilled water, and dried on a chalk stone, or in a filter. When dry, it is called fulminating gold, and detonates by heat; as may be shewn by heating a few grains of it on the point of a knife over the candle. . . . . . . . . . . Fulminating Silver. Dissolve fine silver in pale nitric acid, and precipitate the solution by lime water; decant the fluid, mix the precipitate with liquid ammonia, and stir it till it assumes a black colour; then decant the fluid, and leave it in the air to dry. This product is fulminating silver, which can- not even be touched without producing a violent explosion. Its preparation is so hazardous, that it ought not to be attempted without a mask, with strong glass eyes, upon the face. No more than a single grain ought at any time to be tried as an experiment. . . . . * , , º Mr. Chenevix has invented a less dangerous fulminating sil- ver, which is thus prepared: Diffuse a quantity of alumina through water, and let an abundant current of chlorine gas pass through it. Then digest some phosphate of silver on the solution of the chlorate of alumina, and evaporate it slowly. The produce will then be a hyperchlorate of silver, a single grain of which, in contact with two or three of sulphur, will explode violently with the slightest friction. • * : * Fulminating Mercury. . The mercurial preparations which fulminate when mixed with sulphur, and gradually exposed to agentle heat, are well-knownto chemists; they were discovered by Mr. Bayen. . . . . . . . . . . . Mercury, and most, if not all its oxides, may, by treatment with nitric acid;and alcohol, be converted into a whitish crystal- lized powder, possessing all the inflammable properties of gunpowder, as well as many peculiar to itself. FUNCTION, ANIMAL, applied to the actions of the body, is by physicians divided into vital, animal, and natural. The vital functions are those necessary to life, and, without which the individual cannot subsist; as the motion of the heart, lungs, &c. The natural functions are those which the body cannot subsist any considerable time without, as the digestion of the aliment and its conversion into blood. Animal functions include the senses of touching, tasting &c. memory, judgment, and voluntary motion. FUNCTION. A quantity is said to be a function of another quantity, when its value depends on that quantity and known quantities only ; and it is said to be a function of several quan- tities, when its value depends on those quantities and known quantities only. * * * - - - .’ FUNDAMENTAL Note, in Music, the principal note in a song or composition, to which all the rest are adapted: it is also called the key to the song. - FUNDS, THE PUBLIC, in a political sense, mean the money lent by the nation to government, and known as the National Debt, and for which the lenders, or their assignees, receive For upwards of a century past, the war expenses of the government have far exceeded the produce of the taxes; hence.the government has been compelled to borrow on the security of the taxes on pro- perty; and the accumulated national debt, at the present time, is estimated at about 830 millions, for the re-payment of which, and its interest, 31 millions, all the property of the country, stands mortgaged. The interest of this debt is regularly paid at the Bank of England from the produce of the taxes. Hence it is that persons who have spare money either gladly subscribe to loans, or purchase of public creditors their shares of the public debt, called Stock. There are several kinds of stock or funds, according to the annual interest, as, 3 per cent. stock; 3} per cent, stock; and 4 per cent. stock. . . To purchase stock, or to put money in the stocks, is to become a creditor of the nation, by buying a title to so much interest. Of course, the price of stock varies according as money is more or less plentiful, as there are more or fewer buyers, and as the opinion of public credit is high or low. As £100 produces 5 per cent. at lawful interest, the 4 percent. is at par at £80; the 3} at £70; and the 3 per cent. at £60. The stocks are bigh or low, as they produce less or more than legal interest, and as they vary above or below par. - F U N F U. R. Diction ARY or MECHANICAL science. 343 Sisking FUND. In order to pay off the national debt, Dr. Price suggested, in 1786, an expedient of reserving a million por annum, with which to purchase stock for the public, and to apply all its interest in further purchases, so that the fund should increase in the ratio of compound interest. Upwards of three hundred thousand per annum was afterwards added, and the whole called The Sinking Fund. A farther plan of repayment was adopted in 1792, of appropriating one pound of every hundred borrowed in future, to the same principle of accumulation, it being known that one pound, at compound interest will produce £99 in 94 years, or £60, the par price of the 3 per cents. in 84 years. The accumulation of these vari- ous means had enabled the public commissioners on the 1st of February, 1814, to redeem 234 millions of the debt, to buy up, and to make annual purchases of upwards of eleven millions, so that the whole of the present debt may be redeemed by these means within forty years; supposing, as was actually done in 1823, that five or six millions annually can be appro- priated to this fund. o The expenses of the government, or the supplies required of parliament, amounted, in 1814, to nearly 120 millions per annum, of which 28 millions were for the navy; 39 millions for the army and ordnance; 33 millions for the interest of the national debt; and the rest for the civil list and miscellaneous. During the year ending January 5, 1822, the public expendi- ture was above 21 millions, of which five millions and a half were for the navy, and nine millions and a quarter for the army and ordnance, two millions for the civil list, &c. and five millions for interest of exchequer bills and sinking fund, over and above the interest of the public debt, amounting to 31 millions. . The ways and means for raising the above supplies are, by duties of customs and excise; by assessed taxes, by stamp and legacy duties, and by licenses of various kinds. FUNGI, the name of the 4th order of the 24th class of vege- tables, in the Linnaean system, comprehending the mushroom kind. This order in Linnaeus contains 10 genera. The ancients called fungi children of the earth, to indicate the obscurity of their origin. The moderns have likewise been at a loss in what rank to place them; some referring them to the animal, some to the vegetable, and others to the mineral kingdom. Messrs. Wilck and Munchausen have not scrupled to rank them in the number of animal productions; because when fragments of them, or their seed, were macerated in water, they perceived a quantity of animalcules discharged, which they supposed capa- ble of being changed into the same substance. The mushroom is one of the most perishable of plants, and therefore the most favourable for the generation of insects. Considering the quickness of its growth, it must be furnished with a power of copious absorption ; the extremities of its vessels must be more, dilated than in other plants. Its root seems in many cases to be merely intended for its support; for some species grow upon stones or moveable sand, from which it is impossible that they can draw much nourishment. We must therefore suppose, that it is chiefly by the stalk that they absorb. These stalks grow in a moist and tainted air, in which float multitudes of eggs, so small, that the very insects they produce are with difficulty seen by the microscope. A quantity of these eggs are probably absorbed by the vessels of the fun- gus, and remain there without any change, till the plant begins to decay. - FUNGUS, in Surgery, denotes any spongy excrescence. FUNICULAR MACHINE, is a term used to denote an assem- blage of cords, by means of which two or many powers sustain one or many weights. This is classed by some authors among the simple mechanical powers, and is the simplest of them all. In order to find the law of equilibrium in this machine, we must first reduce all the powers which meet at one point to a single power, by the method of composition of forces; which single power must act in the direction of the cord, this being evidently necessary for establishing an equilibrium; following this method, we may reduce all the powers which act on different points of the cord, to a system of powers acting on the same point. Then to establish the perfect equilibrium, reduce these powers, which act all on the same point, to one equivalent power, and we shall have two powers only, which ought to be equal, and acting in contrary directions. - FUR, in Commerce, the skin of a wild beast dressed in alum, with the hair on; and used as part of dress by persons ofevery rank, according as custom, etiquette, caprice, or wealth, may dictate. The principal part of the furs sold in Britain come from our possessions in Canada, or are brought thither to the merchants by the Indians; and in one year there are tisually purchased, t - e 106,000 Beaver skins, 2,100 Bear do. - 1,500 Fox do. 4,000 Kite fox do. 4,600 Otter do. 17,000 Musquash do. 32,000 Marten do. 750 l)eer do. 1,800 Mink do. 1,200 Ditto, dressed, 500 Buffalo robes, and an immense quantity of castoreum. All which are received in exchange for goods shipped from this country, as coarse woollen cloths, blankets, arms, ammu- nition, tobacco, Manchester and Glasgow goods, linens, sheet- ings, thread, hardware, cutlery and ironmongery, kettles, pots, shoes, hats, hose, spirits, &c. This will be better illustrated by the following statement:- We will suppose the exchange to be made in the Indian country in 1824-5. - 1. The order for the goods was sent to this country, 6,000 §: skins, 600 Wolverine do. 1,650 Fisher do. 100 Rackoon do. 3,800 Wolf do. 700 Elk do. London, for example, . . . . . . . . . . . . 25th October, 1821. 2. They are shipped from London, .... March, 1822. 3. They arrive in Montreal, ... . . . . . . . . . June, 1822. 4. They are made up in parcels, of 90 lbs. weight each, in * . the course of that summer and winter, ........ . . . . 1822. 5. They are sent from Montreal,........ May, 1823, 6. They arrive in the Indian country, and are exchanged for furs in the following winter, . . . . . . . . . . . . 1823–1824. 7. Which furs come to Montreal,....... September, 1824. 8. And are shipped for London, where they are sold in March and April, and paid for in May or June,.... 1825. Thus the merchants lie out of their money three years, from the time they purchase the commodities in England till they receive their returns, and in all four years are consumed before one order, and its consequent sales, are completely closed. FURLING, the operation of wrapping or rolling a sail close up to the yard, stay, or mast, to which it belongs, and winding a gasket or cord about it, to fasten it thereto. Furling in a Body, is a particular method of rolling up a topsail, only prac- tised in harbour, and is performed by gathering all the loose part of the sail into the top about the heel of the top-mast, whereby the yard having as little rolled on it as possible, appears much thinner and lighter than when the sail is furled in the usual manner, which is sometimes termed, for distinction sake, furling in the bunt. Furling Line, denotes a cord employed in this operation. Furling Lines are generally flat, and are known by the name of gaskets. FURLONG, a long measure, equal to one-eighth of a mile, or forty poles. It is also used in some law books, for the eighth part of an acre. . . FURNACE, is a vessel or building for the purpose of con- taining combustible and fusible matters, whether of coal, or wood, or metal, and so constructed, that great heat may be produced and concentrated. Furnaces are as various as the purposes to which they are applied; but the requisites of a good furnace are, 1. To be able to concentrate the heat, and direct it as much as possible to the substances to be acted upon. 2. To prevent the dissipation of the heat after it is produced. 3. To obtain the greatest quantity of heat from the smallest quantity of fuel: and 4. To be able to regulate at pleasure the necessary degree of heat, and have it wholly at the artist's management. As far as furnaces were necessarily connected with the word Chemistry, we noticed them under that article: we shall in this, though it be in fact but a more extensive application of chemistry, describe some particular furnaces. We premise, however, that under the word Bep- Lows, we have shewn how a continued blast may be kept up in any forge or furnace. 344 F U. R. R U R. DICTIONARY or MECHANICAL, so IENCE. FuRNAce for Consuming its own Smoke-Fig.1 represents a vertical section, and fig. 2 a. front view of a steam boiler, furnished with a smoke con- suming furnace, and the same letters refer in both to the same parts of the construction. The opening A, through which the fuel is introduced into the furnace, is shaped somewhat like a hopper, and . is made of cast iron, built into the brick work H. H. From the mouth it inclines down- ward to the place where the fire rests at the bottom of the grate B. The coals in this hopper answer the purpose of a door, and those that are lower are brought into a state of ignition before they are forced into the furnace. A ºr shutter of thin plate-iron is sometimes laid over the hop- per, to prevent the entrance of air by that passage. Be- low the lower plate of the hopper K, e. the furnace is provided with a grated door'." G, kept in its position by the ºilº catch L, which not only serves - to admit air to the fuel, but allows the workmen to push back the fuel from time to time, from c. to d, to make room for fresh quantities to fall into the furnace from the hopper. The refuse of the fuel is cleared out by opening the grated door. The smoke passes from the raw coals over those burning, by the breast b, before it can reach the flue FFF. In this way it is burned, and but a small quantity escapes up the chimney. However, by a simple contrivance of a cast-iron plate a n, above the fuel, a space is left between it and the hopper, for the admission of fresh air, a thin stream of which rushing down the opening, comes in contact with the smoke given out by the freshest coal, and mixing with it in its passage over the fuel in a high state of combustion, enables it to enflame it so com- pletely, that not a particle of smoke ever escapes undecomposed. Blast FuRNAce for Smelting Iron, with part of the Blowing Machine. A is the regulating cylinder, 8 feet diameter, and 8 feet high. B, the floating piston, loaded with weights pro- portionate to the power of the machine. C, the valve by which the air is pressed from the pumping cylinder into the regula- tor: its length 26 inches, and breadth 11 inches. D, the aper- ture by which the blast is forced into the furnace. Diameter of this range of pipes, 18 inches; the wider the better, as occa- sioning less friction, and affording a more powerful column of air. E is the blowing or pumping cylinder, 6 feet diameter, 9 feet high: journey of the piston in this cylinder, from 5 to 7 feet per stroke. Fis the blowing piston, and a view of one of the valves, of which there are sometimes two, sometimes four, distributed over the surface of the piston. G, a pile of solid stone building, on which the regulating cylinder rests, and to which the fianch and tilt of the blowing cylinder are attached. H, the safety valve, or cock; by the simple turning of which the blast may be admitted to or shut off from the furnace, and passed off to a collateral tube on the opposite side. I, the tuyere, by which the blast enters the furnace. The end of the tapered pipe, which approaches the tuyere, receives small pipes of various diameters, from 2 to 3 inches, called nose pipes, which are applied at pleasure, and as the strength and velo- city of the blast may require. K, the bottom of the hearth, 2 feet square. L, the top of the hearth, 2 feet square. KL, the height of the hearth, 6% feet. L is also the bottom of the bushes, which terminate of the same size as the top of the hearth, only the former are round and the latter square. M, the top of the bushes, 12 feet diameter, and 8 feet perpendicu- lar. N, the top of the furnace, at which the materials are Fig. 1. charged, commonly 3 feet diameter. NN, the internal cavity of the furnace from the top of the bushes, 30 feet high. NR, total height of the internal parts of the furnace, 443 feet. O O, the lining of fire-bricks, 13 inches long, and 3 inches thick. --------- - F. - s s SSS S. ss s SS: s 43 § Fºss. - sil ss - s 'E s j|| s s s sº ss. - ss SS SSS s s ss --~~ º §§§ Eº- ſº ºšš Hºss ||| | ºs --- §ss | a ſºlºiſ Hºss º | Ess | - Allºlilºlºs- | *Tºº Hºss sºss SSS | Al S. TKET’ſ TDF PP, a space all round, three inches broad, filled with coke dust, to allow for expansions and contractions of the inner brick lining. Q Q, the second lining, similar to the first, R, a cast-iron intel, on which the bottom of the arch is supported. RS, the rise of the arch. ST, the height of the arch on the outside, 14 feet, and 18 feet wide. VV, the extremes of the hearth, 10 feet square. This and the bush stones are usually made from a coarse-grained freestone, whose fracture presents large rounded grains of quartz, connected by means of cement less pure. Fig. 1 represents the foundation of the - furnace, and a full view of the manner in º which the false bottom is constructed. º % ºf º *; ". . ". stone º of the hearth. 13, ºn the same lºre, is a º 4% stratum of bedding sand. C C, pas- Ž Z º b - w whi ------ % % sages by which the vapours, which may be - generated from the damps, are passed % º - ~~ off. D, D, pillars of brick. The letters ‘…. in the horizontal view of the same figure, correspond to similar letters in the dot- ted elevation. Fig. 2, AA, horizontal section of the diameter of the bushes, the lining and vacancy for stuffing at M. C., is a view of the top of the hearth at L. Fig. 3. A vertical side section of the bushes and hearth, shewing the tymp and dam stones, and the tymp and dam plates. a, the tymp stone, b, the tymp plate, which is wedged firmly in the stone, to keep it firm in case of splitting by the great heat. C, the dam stone, which occupies the whole breadth of the bottom of the hearth, excepting about 6 inches, which, when the furnace is at work, is filled every cast with strong sand. This stone is surrounded by an iron plate of considerable thickness, and of a peculiar shape, d, and from this called the dam plate. The top of the dam stone and plate is two, three, or four inches under the level of the tuyere hole. The space betwixt the bottom of - 2. º º Fig. 2. ' F U R F U S 345 DICTIONARY OF MECHANICAL SCIENCE. the tymp and the dotted line is rammed full of strong sand;. and sometimes fine clay. This is called the tymp stopping, and prevents any part of the blast from being unnecessarily expended. . . . . . . . . . - . . . The furnace being finished, the bottom and sides of it, for two feet up the square funnel, receive a lining of common brick upon edge, to prevent the stones from shivering or mouldering, when the fire comes in contact with it. On the front of the furnace is erected a temporary fire-place, about 4 feet long, into the bottom of which are laid corresponding bars. The side walls are made so high as to reach the under surface of the upper tymp stone; excepting a small space, which after- wards receives an iron plate 1% inch thick, by way of cover. This also prevents the tymp stone from injury by the flame. A . fire is now lighted, and fed with small coals, and as the whole cavity of the furnace serves as a chimney for this fire, the draught is consequently violent, and the volume of heat car- ried up is very considerable. In the course of three weeks, the furnace will be sufficiently dried for the reception of the iron materials. By the introduction of a few baskets of loose fuel and coke, upon the bottom of the ſurnace, then more, and so on, as it ignites, the furnace is filled, or {ths filled. The furnace before us will contain 900 baskets of coke, each 110 lbs. or 99,000 lbs. of coke in all; and every third day this is renewed, when the furnace is fully worked. The operation of the furnace is kept up by specific quantities of coke, iron- stone, and blast-cinders, being added. The descent of the charge is facilitated by opening the furnace below two or three times a day, throwing out the cold cinders, and admitting for an hour or two a fresh body of air, when the iron-stone begins to fuse, and drop like lava through the iron bars. The filling above is regularly continued till the furnace acquires a good heat above, and then the blast is introduced as follows: - The dam stone is laid in its place, firmly imbedded in fine clay; the dam plate is again imbedded on this with the same cement, and is subject to the same inclimation. A channel is made for the scoria, down which it flows in large quantities. The tuyere hole is now opened, and lined with a mixture of fine clay and loam,_the blast is introduced, at first with a smalſº discharging pipe, which is afterwards increased, and in a few hours a quantity of lava will be accumulated. By various minor operations, the metal is finally conducted into moulds, or sows, and when detached from these, is termed pig iron. In six days after the commencement of blowing, the furnace ought to have worked itself clear. - Iron is a well-known metal, of a livid grayish colour, hard and elastic, and capable of receiving a high polish. Its weight is nearly eight times as great as that of water. It is seldom found in a native state, but occurs abundantly in almost every coun- try of the world in a state of oxyde, and mineralized with sul- phuric, carbonic, and other acids. It is found in plants, in several kinds of coloured stones, and even in the blood of animals. After iron ore has been dug out of the earth it is broken into small pieces by machinery, then washed, to detach the grosser particles of earth which adhere to it; then thrown into a furnace, as described above, mixed with a certain por- tion of limestone and charcoal, for the purpose of being melted. Near the bottom of each furnace there is a tap-hole, through which the liquid metal is discharged into the furrows of a sand bed. The larger mass, or that which flows into the main ſurrow, is called a sow; the smaller ones are denominated pigs of iron; and the general name of the metal in this state is cast iron. Cast iron is distinguishable by its properties of being, in general, so hard as to resist both the hammer and the file, being extremely brittle, and for the most part of a dark gray or blackish colour. A great number of useful and important articles are formed of cast iron, such as stoves, grates, chimney backs, pots, boilers, pipes, cannon shot, &c. These are made by casting ladles, full of the rough metal into moulds shaped for the purpose, in sifted sand. f * Wrought iron. The process of converting cast iron into wrought or malleable iron, is called blooming. The cast iron is put into a furnace, and melted by the flame of combustibles, which is made to play upon its surface, a workman constantly stirring it, until, notwithstanding the continuance of the heat, it gradually acquires consistency and congeals. It is then taken out while hot, and violently beaten with a large hammer worked by machinery. See Forge Hammer. formed into bars for sale. By means of this metal the earth has been cultivated. . Without it, houses, cities, and ships could not have been built; and few arts could have been prac- tised. It forms also the machinery by which the most useful and important mechanical powers are generated and applied. In this state it is . Steel is usually made by a process called cementation. This process consists in keeping bars of iron in contact with pow- dered charcoal, during a state of ignition for several hours in earthen troughs, or crucibles, the mouths of which are closed up with clay. cool slowly, becomes soft; but if it be plunged whilst hot into cold water, it acquires extreme hardness. Steel, if heated to redness, and suffered to - And by heating steel to different degrees, it receives different degrees of tem- per, from that which renders it proper for files, to that which fits it for the manufacture of watch-springs. All kinds of edge tools, where excellence is required, are made of steel; and a steel instrument may be known from an iron one, by letting fall upon it a drop of aqua-fortis; if it be steel, this will occa- sion a black spot, but if it be iron, it will not have this effect. FURNITURE, in Dialling, certain additional points and lines drawn on a dial, by way of ornament rather than utility, such as the signs of the zodiac, length of the days, parallels of declination, azimuths, points of the compass, meridians of chief cities, Babylonic, Jewish, or Italian towns. FUSE, of a Bomb or Grenado, is that which makes the whole powder or composition in the shell take fire. Fuses are chiefly made of dry beech-wood or hornbeam. The composi- tion of fuses is saltpetre 3, sulphur 1, and mealed powder 3, 4, or five parts. - FUSEE, in Clock Work, is that part drawn by the spring, and about which the chain or string is wound. - FUSIBILITY, that quality of metals which renders them liquid; or perhaps, we may define fusibility to be the property in metals, which, when a strong heat is applied to them, per mits the atoms of which they are composed, to disengage themselves, and become soluble or fluid. Gold is more fusible than iron or copper;--or, the atoms, of which it is composed have a readier affinity to heat than iron or copper, and do thereby separate into an infinity of particles sooner than iron or copper. But silver, tin, and lead, are dissolved sooner than gold, which shews that the atoms of these metals have a greater affinity to the heat applied to them than gold. Borax and some other substances are frequently mixed with metals to render them more fusible, which shews either that the borax augments the heat, or that a particular affinity takes place between the metal and borax, in the affection of both to become liquid, by their attraction or cohesion. - FUSILEERS, in the British service, are soldiers armed like the rest of the infantry, with this difference, that their muskets are shorter and lighter than those of the battalion and the grenadiers. : FUSION, the action of fire, or rather of caloric, on solid bodies, by which they are made to pass into the state of fluidity, and a body rendered liquid by fire is said to be in fusion, that is, to flow or melt. Some bodies cannot be rendered fluid by any heat. These are called infusible, or fire-proof. Several of them may, however, be fused by adding other bodies, which are called fluxes. See FLUX Es. FUST, or Faust, Joh N, a goldsmith of Mentz, and one of the three artists who invented the art of printing. Guttemberg invented wooden blocks, which resembled the stereotype plates of the present day. Schaefer, the son-in-law of Fust, invented punches and matrices, by means of which this noble art was carried to perfection at once : and Fust supplied money to carry on the business. Fust visited Paris in 1466, to sell a second edition of his Bible, and died of the plague, which carried off 40,000 souls in the months of August and September alone. The monks, whom printing deprived of emoluments arising from the copying of manuscripts, afterwards invented the romance of Faustus, the magician, and his selling himself to the devil for 24 years, just as John Tzetzes, the monk, in his Chiliads of the Twelfth Century, palmed upon the world the romantic tale of Belisarius. Now Belisarius did not lose his sight, nor was he ever reduced to beggary, though, from a con- º 4 T 346 F U T. F U S DICTIONARY OF MEGHANICAL SCIENCE. spiracy formed against the veteran general, he was accused to Justinian, as a rebel: his life was spared, but his fortunes were sequestered, and from June to December he was guarded as a culprit in his own palace. But at length his innocence was acknowledged, his freedom and honours restored, and eight months afterwards he died in his own palace. füSTIAN, a cloth made of cotton yarn, both woof and warp, though many cloths of this name are made, of which the warp is flax, or even hemp. tº º FUSTIC, Yellow Wood. This wood, the morus tinctoria, is a native of the West Indies. It affords much colouring matter, which is very permanent. The yellow given by fustic without any mordant is dull, and brownish, but stands well. The mor- dants which are employed with weld, act on it in a similar manner, and by their gegns the cºlour, is rendered ingre bright and fixed, As it abounds more * colºring matter than weld, a less quantity will suffice. The yelloy of fušić inclines more to orange than that of weld. § FUTTGACKS, the middle diyision of a ship's timbers, orthpse. parts which are situated between the floor and the tº #; Those next the keel are called ground futtocks, º the re; upper futtocks, - - Futtock Shrouds, or Foot Hook Shrouds. The epithef hogk is frequently applied in common language to any thing bent or incurvated, and particularly to several crooked timbers in a ship, as the breast-hooks, fore-hooks, after-hooks, &c. This term is evidently derived from the lowest part or foot of the timber, and from the shape of the piece. G. G. A F G, :the seventh letter of our Alphabet; as a numeral it was used by the ancients to denote 400, and with a line over it, 30,000. In Music, it is the mark of the treble clef; and from sits being placed at the head, or marking the first sound in Guido’s scale, the whole scale took the name of:Gamut. GABEL, a word in old records, signifying a tax, rent, custom, or service, paid to the king or lord. GABIONS, in Fortification, baskets made of osier-twigs, which, being filled with earth, serve as a shelter from the enemy's fire. IGABLE, in Architecture, the upright triangular eqd of a house, from the leaves to the chimney top. ;GAD, among Miners, a punch of iron, with a wooden handle, used to break up the ore. GAD FLY, or Breeze FLY, names given to the black and yellow-bodied oestrus, a fly nearly as large as the common blue flesh-fly. tºolinITE, a mineral found in Sweden, and called after Gadolin, who first ascertained its composition. The colour, a black or brown. It is brittle, and the specific gravity is 4-0497. With borax it melts into atopaz-yellow glass. GADUS, the Cod, a genus of fishes belonging to the order of jugulares, of which there are seventeen species. The general rendezvous of the cod fish is on the banks of Newfoundland, and the coasts of Cape Breton, Nova Scotia, and New England. The cod grows to a very large size: Mr. Pennant mentions a specimen which weighed 78 lbs. and measured 5ft.8in. in length, and 5 ft. in girth round the shoulders; but the general weight is from 14 to 40 lbs. The food of the cod is small fish, worms, testaceous or crus- taceous animals, such as crabs, &c. and its digestion is so 'powerful as to dissolve the greatest part of the shells it swallows. The fishermen are well acquainted with the use of the air blad- der or sound of this fish, and dexterously perforate the living fish with a needle to let out the air contained. The sounds, when salted, are reckoned a delicacy. A species of isinglassis also prepared from this part of the fish by the natives of Iceland. The haddock, whiting, dorse, coal fish, ling, and turbot, are spe- cies of the cod. - GAFF, a-sort of boom, used in small ships, to extend the upper edge of the mizzen, and employed for the same purpose on those sails whose foremost edges are joined to the masts by hoops or lacings, and which are usually extended by a boom below; such are the main-sails of sloops, brigs, and schooners. The foremost end of the gaff is furnished with two cheeks forming a semicircle, which enclose the after part of the mast, and is secured in this position by a rope passing from one of the cheeks to the other on the fore side of the mast, on which are strung several small wooden balls, called trucks, to lessen the friction of the rope on the mast when the sail is hoisting or lowering. It is further secured in this situation by a rope passing from one of the cheeks to the other on the fore side of KG. A. G. the mast, and to prevent the friction of this rope upon the mast, by hoisting or lowering, several little wooden balls, called 'trucks, are hung upon it, in the same manner as beads are hung upon the Indians’ strings of wampum. * * = & ' -- GAGE, is a term employed to denote various instruments used for measuring the state of rarefaction in the air-pump, variations in the barometer, &c. The Gage of the Air Pump is of a variety of forms, as, the Barometer Gage, the Syphon Gage, the Pear Gage, &c. r * ! - -, - . 'Short Barometer GAGE is merely the lower part of a barome- ter, or a tube about eight or nine inches in length, filled with mercury, and immersed with its aperture into a small quantity of the same fluid, contained in a glass vessel which forms the cistern. This gage is either placed under the receiver upon the principal plate of the pump, or it is placed under a sepa- rate small receiver on an auxiliary plate attached to some pumps for this purpose. As this gage is not equal to a whole : barometer, it will not begin to shew the state of rarefaction till after three-fourths of the air have been exhausted, that is, when the elasticity of the remaining air is about one-fourth of that of common air, the barometer itself being but about one-fourth of the usual height of the mercury; but after this, the farther de- crease of elasticity is exhibited by the sinking of the mercury, and a graduated scale attached to the instrument. 3 * There is another gage, called the Long Barometer GAge, which works in a similar manner, and indicates the state of rarefaction on nearly the same principles. 8 Syphon GAge. This differs from the short barometer gage, only in this ; that instead of terminating in a small cistern, in this gage the tube is bent, and rises upwards with its apeiture, which by means of a brass tube is made to communicate with the inside of the pump, so that the ascending leg of the tube performs the office of a cistern. • . . * * * * Pear, GAge. This is the invention of Mr. Smeaton, and is , thus denominated from its form, which resembles that of a pear. This gage does not indicate the rate of rarefaction as it pro- ceeds, but shews the ultimate state. to which it. was carried after the re-admission of the air. The gage is suspended in the receiver, and exhausted to the same degree; but when this is carried on as far as is intended, the open orifice of the gage is let down into a vessel of mercury, which, upon the re-admis- sion of the air, is forced into the pear, and thus the ultimate state of rarefaction is determined. > * * & GAge of the Barometer, is a contrivance. for estimating, the exact degree of the rise or fall of the mercury in the barometrical tube. It is obvious, that when the mercury sinks in the tube it rises in the cistern, and vice versa; and as the distance between the divisions graduated on the annexed scale, and the surface of the mercury in the cistern, is not truly shewn by the num- ...bers on the scale, errors must happen in determining the exact height of the mercury. To remedy this inconvenience, a line is cut upon a round-piece of ivory, which is fixed near the G A G DigrionARY 9F cistern; this line is accurately placed at a given distance from § º: # instaflèë,'twenty-seven"ifiches; and a sºiáñ floaf §§ With 3 cylindric piege of ivory fixed tº its upper Hüifacé, (of whith 37 line must be cut at a distance of two iščhes; exactly"from the under surface" of the cork;) is left töğlay freely' on the º ‘and the 'cylinderworks in a groºve inádé in the other piece; from this godstruction it ap: peãfs, that if 'thèse marks are made to cºinéide, by raising or Iowering “the $ºrew which “acts on the "úuicksilver, then the divisions th the scăle will express the 'true measure of the dis- tänge fröm thé surface." ; : . . ;- 1 : “ . . . . . . . . ." . . cº- . . . . . . . . " * GAGE of the Cohdenser, is a glass tube of a particular con- struction, adapted to the coriderišing engine, add thesigned to shew the exact density'and quantity of the air contained at any time if the döndenser. * * * * * * : " ". . . . . . º “Seá Gääe, is an instrument invented by Dr. Hales and Dr. Desagulièrs, for finding the depth"ºf the sea, the descriptiºn bf which is this. "A Bin'the annexed figure, is the gage-bottle, in * which i is' cemented the “” t; f * : * * * *, *, * 't, v . . . . . . . . . 'gagé-tūbe Ef, in the bråss cap at G. The uppér end of the tube E, is hermetically lan sèaléd, and the ‘open lower { . end f, is immersed in mer- cury, marked" C, on which | swims "a 'small quantity of iſ . treagle." On the top of the bottle is screwed a tube of ºbrass H G, pierced with seve- || ral holes, to admit the water . . . into the bottlé’ A. B. The body K, is a weight hang- ‘ing by its shank L, in a socket ‘N; with a notch on one side at m, in which is fixed the ëatch l of the spring s, and ‘passing through the hole L, in the 'shank of the weight K, ‘prèvents its falling out when tonce hung on." On the top, - ..in the upper part of the brass. * * . . * , ; ; ; ; , º, & tube at H, is fixed a large empty ball, or full-blown bladder I, ‘which must not be so large, but that the weight K may be able to sink the whole under water. The instrumehtthus construct- ed, is used in the following manner:—The weight K being hung on, the gage is let fall into deep water, and sinks to the bottom; the socket N is somewhat longer than the shank; 'L, and therefore, after the weight K comes to the bottom, the ‘strikes against the weight; this gives liberty to the catch to fly: off the hole, whereby the weight K is disengaged; when this is done, the ball or bladder, I, instantly buoys up the gage to the top of the water. While the gage is below, the water, having free access to the treacle and mercury in the bottle, will by its pressure force it up into the tube; and Ef, the height to which łit has been forced by the greatest pressure, viz. that, at the :bottom, will be shewn by the mark in the tube which the treacle leaves behind it, and which is its only use. This shews into ‘what space the whole air in the tube Ef is compressed, and consequently the height or depth of the water, which by its weight produced that compression, which is the thing required. . . . . . . . . . . . . . . . . . " * . . . If the gage tube Ef were of glass, a scale might be drawn on it with the póint of a diamond; shewing by inspection what height the water stands above the bottom. But the length of 10 inches is not sufficient for fathoming depths at sea, because, when all the air in such a length of tube is compressed into half an inch, the depth of water is not more than 634 feet, which is not half-a-quarter of a mile. . . . . . . . . . . ‘...If to remedy this, we make use of a tube 50 inches long, which for 'strength may be a musket-barrel, and suppose the air compressed into an hundredth part of an inch; then by saying, as 1: 99 :: 400: 39000 inches, or 3300 feet; even this is ; but little more than half a mile, or 2640. But since it is reasonable to suppose the cavities of the 'sea bear some * * * * > . . J MECHANI i . * } f * * I & 8 * ‘. ... I { } { ..}. use in letter cutting, and making of moulds. s proportion to the mountainous parts of the land, some of which I QAL SCIENC C \, , , \' , \ , C & 'C': }. à. G A L. 347 * {{! : | are more than three miles above the earth's surface; therefore, to explóre stréh great depths; Dr. Haléééâtrived a new for flºor his spa'ſſage, brfäther fºr the gage-tube if it, which is as foil lºws:-B.º.B F, is a hollow metallic globe, communicating on the top with a long tube A B, whose capacity is a ninth paſt ºf that‘globe: 'On the föwer part at D; it has also a shortºtabé DE,” to stand in the mercüry and treacle: The aircontained in the coinſ build 'gage-tube is compressed by the water as before; but the degreš of €ompression; of height to which the treacle hāš been forced, cannot here be seen through the tube; therefore; to answer that end, a slender rodſ of metal or wood. with a "knob of the top of the tube AB, will receive the j. of the treacle, and shew it when taken out, g º 'º jº If the tube A B be 50 inches long;' and of such a bore that every inch if fength shall be a cubic inch of air, and the con- tents of the globe and tube together 500 cubic inches; then, when the air is compressed within an hundredth part of the Whole, it is evident the treacle will riot approa&h nearer than fiye inches of the top of the tube, which will agree to the depth of 3300 feet of water as above. Twice this depth will compress the air into nearly half that space, viz. 2; inches, corresponding to 6600, which is a mile and a quarter. Again, half that space or 13 inch, will shew double the former dépth, viz. 13:200 feet, ; 24 miles, which is probably very nearly the greatest-depth of ie Sea: " " ' ' ' ' ' . . . . . . . . . . . . . . . . . ; ; ; , ; ; ; , ; ; ; , , , , , ; ... Bucket Sea GAge, is an instrument contrived by Dr. Hales to find the different degrees of coolness and saltness df the sea, at different depths, consisting of a common household pail or bucket with two heads to it. These heads have badh a round hole in the middle, near four inches diameter, and covered with Valves opening upwards, and that they may both open and shut together, there is a small iron rod fixed to the upper part of the lower valve, and at the other end to the under part of the upper valve; so that as the bucket descends with its sink- ing weight into the sea, both the valves open by the force of the water, which by that means has a free passage through the bucket. . But when the bucket is drawn up; then both the yalvés shut by the force of the water at the upper part of the bucket; whereby it is brought up full of the lowest sea-water to which it has-descended; - ... When the backet is drawn up, the mercurial thermometer, fixed in it, is examined; but great care must be taken to 'observe the degree at which the mercury stands, before the lower part of the thermometer is taken out of the water, in the "bucket, as it would otherwise be altered by the different tem- perature of the air. In order to keep the bucket in a right position, there are four cords fixed to it, reaching about four feet -- - | below it, to which the sinking weight is attached. . . . . . . . gage will continue to descend, till the lower part of the socket;|. Tide GAge. This is an instrument used for determining the height of the tides, by Mr. Bayley, in the course of a voyage towards the south pole, &c. in the Resolution and Adventure, in the years 1772, 1773, 1774, 1775. This instrument consists of a glass tube, whose internal diameter was seven-tenths of an inch, lashed fast to a ten-foot fir rod, divided into feet, inches, and parts; the rod being fastened to a strong post fixed firm and upright in the water. At the lower end of the tube was an exceedingly small aperture, through which the water was admitted. In consequence of this construction, the surface of the water in the tube was so little affected by the agitation of the sea, that its height was not altered the tenth-part of an inch, when the swell of the sea was two feet, and Mr. Bayley was certain, that with this instrument he could discern a differ. ence of the tenth of an inch in the height of the tide. . . . Wind GAGE, is an instrument for measuring the force of the wind upon any given surface. See ANEMoMeter. . . . . . . GAGE, among Letter Founders, a piece of box, or other hard wood, variously notched; the use of which is to adjust the dimensions, slopes, &c. of the different sorts of letters. There are several kinds of these, as the flat-gage, the face-gage, the italic-gage, &c. : . . . . . . . . . . * : * : « GAGE, Sliding, a tool used by Mathematical Instrument- makers, for measuring and setting off distances. It is, also of GAIANTHÚs, the Snow Drop, a genus of the monogynia order; in the hexandria class of plants, and in the , natural method ranking under the ninth order, spathaceae. . . . . . 348 G. A. L. G A L. DICTIONARY of MECHANICAL SCIENCE. GALAXY, VIA LActea, or Milky Way, in Astronomy, that long, luminous track or zone, which encompasses the heavens, forming nearly a great circle of the celestial sphere. It is inclined to the plane of the ecliptic at about an angle of 60°, and cuts it nearly at the two solstitial points. It traverses the constellations Cassiopeia, Perseus, Auriga, Orion, Gemini, Canis Major, and the Ship, where it appears most brilliant in southern ſatitudes; it then passes through the feet of the Cen- taur, the Cross, the southern Triangle, and returns towards the north by the Alter, the tail of the Scorpion, and the arc of Sagittarius, where it divides into two branches, passing through Aquila, Sagitta, the Swan, Serpentarius, the head of Cepheus, and returns into Cassiopeia. Milton also speaks of it in the following beautiful, and appro- priate language:— •r - 3. “ A broad and ample road, whose dust is gold, And pavement stars, as stars to thee appear, Seen in the Galaxy, that milky way, Which nightly, as a circling zone thou seest, Powdered with stars.” - The ancients had many singular ideas as to the cause of this phenomenon; but modern astronomers have long attributed it to a great assemblage of stars, and Dr. Herschel has confirmed these conjectures, having discovered, in a space of about 15° This, however, instead of satisfying the curiosity of astronomers, only gave long, by 29 broad, no less than 50,000 stars. rise to farther inquiries and hypotheses; amongst others, that of Dr. Herschel’s, which is very interesting; he supposes the sidereal universe to be distributed into nebulae and clusters of stars, and the milky way to be that particular cluster in which our sun is placed. In a paper on the construction of the heavens, Dr. Herschel says, it is very probable, that the great stratum called the milky way, is that in which the sun is placed, though perhaps not the centre of its thickness, but not far from the place where some smaller stratum branches from it. Such a supposition will satisfactorily, and with great simplicity, account for all the phenomena of the milky way, which, according to this hypothesis, is no other than the appearance of the projection of the stars contained in this stratum, and its secondary branch. - In another paper on the same subject, he says, “We will now retreat to our own retired station in one of the planets attend- ing a star in the great combination with numberless others; and in order to investigate what will be the appearances from this contracted situation, let us begin with the maked eye. The stars of the first magnitude, being in all probability the nearest, will furnish us with a step to begin our scale ; setting off, therefore, with the distance of Sirius or Arcturus, for instance, as unity, we will at present suppose, that those of the second magnitude are at double, and those of the third at treble the distance, and so forth. Taking it then for granted, that a star of the seventh magnitude is about seven times as far from us as one of the first, it follows that an observer, who is enclosed in a globular cluster of stars, and not far from the centre, will never be able, with the naked eye, to see the end of it; for since, according to the above estimations, he can only extend his view about seven times the distance of Sirius, it cannot be expected that his eyes should reach the borders of a cluster, which has, perhaps, not less than fifty stars in depth every where around him. The whole universe, therefore, to him, will be comprised in a set of constellations, richly orna- mented with scattered stars of all sizes. Or if the united brightness of a neighbouring cluster of stars should, in a remarkably clear night, reach his sight, it will put on the appearance of a small, faint, nebulous cloud, not to be per- ceived without the greatest attention. Allowing him the use of a common telescope, he begins to suspect that all the milki- ness of the bright path which surrounds the sphere may be owing to stars. By increasing his power of vision, he becomes certain that the milky way is, indeed, no other than a collec- tion of very small stars, and the nebulae nothing but clusters of stars.” - . Dr. Herschel then solves a general problem for computing the length of the visual ray; that of the telescope which he ases will reach to stars 497 times the distance of Sirius. Now Sirius cannot be nearer than 100,000 x 190,000,000 miles, therefore Dr. Herschel's telescope will at least reach to 100,000 x 190,000,000 × 497 miles. s that in the most crowded part of the milky way, he has had And Dr. Herschel says, fields of view that contained no less than 588 stars, and these were continued for many minutes, so that in a quarter of an hour he has seen 116,000 stars pass through the field of view of a telescope of only 15' aperture: and at another time, in 41 minutes, he saw 258,000 stars pass through the field of his telescope. Every improvement in his telescope has discovered stars not seen before, so that there appears no bounds to their number, or to the extent of the universe. - GALBANUM, a gum issuing from the stem of an umbelli- ferous plant, growing in Persia, and many parts of Africa. GALE, Electrical. On the 6th December, 1823, about 100 miles west of Drontheim, a gale of wind lasted three days without intermission, and afforded the following proofs of its having originated in a disturbed state of electricity in the atmosphere. It was accompanied by frequent and vivid lightning, unusual in high latitudes in winter; and at the mast- heads and yard-arms of the Griper, commanded by Captain Clavering, not fewer than eight balls of fire were visible at OT1C0, & - - - . . . GALENA, in Mineralogy, the sulphuret of lead, found both in masses and crystallized. The primitive form of its cryſtals is a cube. Its colour is bluish gray like lead, but tº: Lustre metallic. Texture foliated. Fragments cubical; Soft but brittle. Specific gravity 7-22 to 7.587. Effervesces with nitric and muriatic acids. It is composed of from 45 to 83 Iead, and from 0.86 to 16 of sulphur. It generally contains some silver, and sometimes also antimony and zinc. GALENIC, or GALENICAL, in Pharmacy, a manner of treating diseases, founded on the principles of Galen, in opposition to the chemical practitioners. - GALEOPITHECUS, CoLUGo. A genus of quadrupeds, natives of the Molucca and Philippine islands, frequenting woody places, and feeding principally on fruits. The Colugo resides on trees, and in descending from the top of a tree, it spreads its membranes, and balances itself to the place it aims at in a gentle manner; but in ascending, it uses a leaping pace. The whole length of the animal is about three feet; the breadth, when expanded, nearly the same; the tail is slender, and about a span long. The membrane, or expansile skin, by which it is enabled to fly, is continued on each side, from the neck to the fore feet, thence to the hind feet, and again to the tail : it is covered with fur, in the same manner as the body. The whole upper side of the animal is generally of a deep ash colour, and the whole under side, both of the body and membrane, is yel- low. The head is long. The ears are small, round, and marked internally by numerous semicircular transverse streaks. The legs are clothed with a yellow down : there are five toes on each foot, united by a membrane, and terminating in crooked claws. This animal is called by the Indians caguang, colugo, and gigua. It was first described by Bontius, in the history of Java, GALILEO, GALILei, a very celebrated mathematician and astronomer, was the son of a Florentine nobleman, and born in the year 1564. He had from his infancy a strong inclination to philosophy and the mathematics, and made prodigious pro- gress in these sciences. In 1592 he was chosen professor of mathematics at Padua, and during his abode there ke is said to have invented the telescope; or, according to others, improved that instrument, so as to render it fit for astronomi- cal observations. In 1611, Cosmo II. Grand Duke of Tuscany, sent for him to Pisa, where he made him professor of mathema- tics, with a handsome salary; and soon after, inviting him to Florence, gave him the office and title of principal philosopher and mathematician to his highness. In 1612 he discovered some spots on the sun's disc, which led to the publication of a pam- phlet asserting the truth of the Copernican system of astronomy. For this he was cited before the inquisition at Rome; and after some months' imprisonment, released, on a simple promise that he would renounce his heretical opinions. In 1632 he published his dialogues on the Ptolemaic and Copernican systems of the world, for which he was again cited before the Inquisition, imprisoned, his book burned, and condemned to repeat once a week, for three years to come, seven penitential G. A. L. G-A L DICTIONARY OF MECHANICAL SCIENCE. 349 psalms, as a saving penance for his heresies. He lived ten years after this, and died in 1642, in the 78th year of his age. For the purpose of astronomical observations, he improved the telescope, first invented by Jansen, and was himself the contriver of the simple pendulum; and thought of applying it to clocks, but did not execute that design. He, together with his pupil Torricelli, discovered that air had gravity, and endeavoured to compare it with water. As a great promoter of the sciences, he opened vast fields for the inquiries of others, and ably assisted them by his inventions and discoveries. Galileo wrote a number of treatises, many of which were published in his lifetime. Many of his pieces were, however, lost at his death, as some say, through the Superstition of one of his nephews, or, as others say, through the artifice of his wife's confessor; at all events, they were destroyed, in con- sequence of their being supposed to contain doctrines which the Inquisition declared to be heretical. GALL, in the animal economy, the same with bile. GALL Bladder, called Vesicula, and Cystis Fellia, is usually of the shape of a pear, or the size of a small hen’s egg. It is situated on the concave side of the liver, and lies upon the colon, part of which it tinges with its own colour. It is composed of four membranes, or coats; the common, the vesicular, the mus- cular, and the nervous one, which last is of a wrinkled or º surface within, and furnished with an unctuous liquºr. The use of the gall-bladder is to collect the bile, se- cretéd in the liver, and mixing with its own peculiar produce, to perfect it farther, to retain it a certain time, and then to expel it. GALL, in Natural History, denotes any protuberance or tumour produced by the puncture of insects on plants and trees of different kinds. Galls are of various forms and sizes, and no less different with regard to their internal structure. Some have only one cavity, and others a number of small cells com- municating with each other. Some are as hard as the wood of the tree they grow on, others are soft and spongy; the first are termed gall nuts; and the latter berry galls, or apple galls. Oak-galls, put into a solution of vitriol in water, give it a purple colour, which, as it grows stronger, becomes black, and on this property depends the art of making our writing ink and dyes. 'ºrº Stones, calculous concretions frequently formed in the gall bladder, and sometimes occasioning great pain in their passage through the ducts into the duodenum, before they are evacuated. Gall-stones often occur in the inferior animals, particularly in cows and hogs; but the biliary concretions of these animals have not hitherto been examined with much attention. Soaps have been proposed as solvents for these calculi. The academy of Dijon has published the success of a mixture of essence of turpentine and ether. GALLATES, salts formed by the gallic acid with alkaline earths or metallic bases. GALLERY, a balcony, projecting from the stern or quarter of a ship of war, or of a large merchantman. Stern GALLERY, that part of the preceding article which is wholly at the stern of the ship, and is usually decorated with a balustrade extending from one side of the ship to the other; the forepart is limited by a partition, called the skreen bulkhead, in which are framed the cabin windows, and the roof of it is formed by a sort of vault, termed the cove, which is frequently ornamented with sculpture. Quarter GALLERY, is that part which projects on each quar- ter, and is generally fitted up as a water closet. Ships of twenty guns and upwards, on one deck, have quarter galleries, but no stern gallery; two and three deckers have two or three of these conveniences on each side, one under the other, and one or two stern galleries. GALLERY, in Architecture, a covered place in a house, usually in the wings of a building, its use being chiefly to walk in. GALLERY, in Fortification, a covered walk across the ditch of a town; and as a mine, it is a narrow passage from one part of the mine to another. yº GALLEY, a kind of low flat-built vessel, furnished with one deck, and navigated with sails and oars, particularly in the Medietrranean. The largest sort of these vessels, called l parent plates. galleasses, were formerly employed by the Venetians; they - were about 162 feet long above, and 133 : feet by the keel, 32 feet wide, and 23 feet , length of sternpost. They were furnished with three masts, and A 32 banks of oars, each § bank containing two ºf oars, and every oar =s===, being managed by six or seven 'slaves, who were usually chained thereto. In the forepart they had three small batteries of cannon, viz. two 36-pounders, two 24-poun- ders, and two 2-pounders; they had also three 18-pounders on each quarter, and carried from 1000 to 1200 men. The galleys next in size to these are called half-galleys, and are from 120 to 130 feet long, 18 feet broad, and 9 or 16 feet deep. They have two masts, which may be struck at pleasure, and are fur- nished with two large lateen sails, and five pieces of ean- non. They have commonly É twenty-five banks of oars, as * described above. A size still quarter galleys, carrying from 12 to They generally keep close under the shore, *=} fl- 16 banks of oars. but sometimes venture out to sea to perform a summer cruise. In France are forty galleys for the use of the Mediterranean, the arsenal thereof being at Marseilles. The general of the galley bears a double anchor, placed in pale behind the escutcheon of his arms, as a mark of his office. The captain galley is the principal galley of a state, commanded by the captain-general of the galleys. In France, before the Revolu- tion, the royal galley was the first. These galleys in France resemble the hulks of Britain, in which the convicts labour, and are confined. GALLEY, is also a name given to an open boat, rowing six or eight oars, and used on the river Thames by custom-house officers, press-gangs, and also for pleasure; hence the appella- tion of custom-house galley, press-galley, &c. GALLEY, or Gally, is also the name of the kitchen of a ship of war, or the place where the grates are put up, fires lighted, and the victuals generally boiled or roasted. In East India ships it is generally termed the cook-room, and on board of merchantmen it is called the caboose. GALLEY Slave, a person condemned to work at the oar on board a galley, being chained to the deck. Condemnation to the galleys is a punishment peculiar to France, whereby criminals and delinquents are adjudged to serve as slaves on board the galleys, either during life, or for a limited time. A man condemned for perpetuity is dead in a civil sense ; he cannot dispose of any of his effects; cannot inherit; and if he be married, his marriage is null, nor can his widow have any of her dower out of his goods, which, with his lands, are hereby confiscated. GALLIC Acid, in Chemistry, is obtained from the oaknut-gall. In an infusion of galls made with cold water, a sediment is formed which has a crystalline form and an acid taste. By an infusion of galls exposed to the air, and removing now and then the mouldy skin formed on its surface, a large quantity of this sediment was obtained; which being edulcorated with cold water, redissolved in hot water, filtrated and evaporated very slowly, yielding an acid salt in crystals as fine as sand. Or, boil a mixture of carbonate of barytes and an infusion of nut-galls. A bluish green liquid is obtained, which consists of a solution of gallic acid and barytes. Filter and saturate with diluted sulphuric acid. Sulphat of barytes is deposited in the state of an insoluble powder, and a colourless solution of gallic acid remains. Gallic acid when pure, is in the form of trans- Its taste is acid, and somewhat astringent; and when heated it has a peculiar and rather unpleasant aromatic odour. 4 U 850 G A u G. A. L. DICTIONARY OF MECHANICAL scIENCE. GALLINAE, in Ornithology, the fifth order of birds. Under which are comprehended the peacock, pheasant, turkey, the common cock, partridge, grouse, dodo, &c. GALLING FiRe, a repeated discharge of cannon, or small arms, which, by its execution, greatly annoys the enemy. GALLIOT, a Dutch vessel, carrying a main and a mizzen mast, and a large g gaff-main-sail. A galliot is a sort of a brigan- tine, or small galley,built very slightly, and de- signed only for chase. She can both sail & row, and usually car- ries about two drº three pediteros, 1 and has sixteen or twenty oars. All the seamen on board are sol- . o == - diers, and each has a musket by him on quitting his oar. Some also call the bomb-ketches galliots. GALLON, an English measure of capacity, being equal to º ſº jālūlū **º-º:*::Fººt...º.º.º-ºº-º-º-º-º: 4 quarts or 8 pints. - Cub. Inches. The gallon, wine measure, contains... . . . . e º 'º ºf Ditto, beer measure, ... . . . . . . . . . . . . . . . . 282 Ditto, dry measure, . . . . . . . . . . . . . . . . . . . . 2684 GALLOON, in Commerce, a narrow kind of lace used to edge or border cloths. * GALLOWS Bits, a frame of timber, in form of a gallows, forming a support for the spare topmasts, yards, and booms. GALVANI, Lewis, a modern philosopher, who has had the honour of giving his name to a newly discovered principle in nature, was born at Bologna, in 1737, where he practised medi- cine, was public lecturer at the university, and reader in anatomy in the Institute of the same city. His reputation, as an anatomist and physiologist, was established in the schools of Italy, when accident gave birth to the discovery which has immortalized his name. His wife, with whom he lived many years in the tenderest union, was at this time in a declining state of health. As a restorative, she made use of a soup of frogs; and some of these animals, skinned for the purpose, happened to lie upon a table in her husband's laboratory, upon which was placed an electrical machine. One of the assistants, in his experiments, happened accidentally to bring the point of a scalpel near the crural nerves of a frog, lying not far from the conductor. Instantly the muscles of the limb were agitated with strong convulsions. Madame Galvani, a woman of quick understanding, and of a scientific turn, was present, and, struck with the phenomenon, she immediately went to inform her husband of it. He came, and repeated the experiment; and soon found that the convulsion only took place when a spark was elicited by the conductor. It was Volta, however, who brought to a system the crude and erroneous opinions of Galvani, who would have within all animals a peculiar electri- cal fluid, secreted by the brain, and diffused by the nerves through various parts of the body. However, from this simple experiment, or rather accident, arose the new science of Galvanism, which has made, and is still making, such a rapid progress in the hands of modern chemists and philosophers. Galvani died in 1798, in the 61st year of his age. GALVANISM, a modern and very interesting branch of science, thus named after its celebrated discoverer, professor Galvani, of Bologna. (See the preceding article.) Galvanism comprises all those electrical phenomena arising from the chemical agency of certain metals with different fluids. We have noticed, in the foregoing article, the humble origin of this science; and that by accident it was discovered, that common, electricity had the property of producing muscular contractions in the limbs of animals even a considerable time after death; and of this Galvani more clearly convinced himself, by ascertaining, that from whatever source the electricity was drawn, the effect of it was still the same. But in one instance he found, that the mere agency of a metallic substance, where he had no reason to suspect the presence of electricity, the limbs of a recently killed frog were convulsed; and after mak- ing several experiments, he ascertained, that the convulsions only took place when he employed dissimilar metals. . Galvani's experiments were repeated by many eminent philo- sophers, both on the continent and in this country. None of them, however, added any thing new to what Galvani had him- self discovered, excepting the celebrated Volta, whose improve- ment was so decided, that the science itself has nearly changed its name, taking that of Voltaism instead of Galvanism. ... ' When we view, indeed, the numerous facts that have been added to the labours of Galvani, his discoveries form but a very small part of the whole mass, whereas a great many of them are due to Volta. Yet when we recollect again, that the inves- tigation began with the former, and was in a great degree. promoted by his own perseverance, we must ever consider him as a principal in this extensive field of research ; and cannot, without injustice, deprive him of the honour which has been ; conferred upon him, of giving his own name to the science which he discovered and promoted. Philosophy, however, is infinitely indebted to Signior Volta, it being to him that we owe, in a great measure, the rapid progress that has since been made in this interesting branch of philosophy. He repeated the experiments of Galvani, and found, that when two pieces of metal of different kinds were placed in different parts of an animal at the same time, that the metals were brought in con- tact, or were connected by a metallic arc; as often as the contact was made, convulsions were observed. He found that the greatest was produced when the metals were zinc and silver. When several pairs of metals were employed, having pieces of moist cloth between them, the effect appeared to increase as the number of pairs. This important discovery of accumulating the effects of this species of electricity, was made by Volta in 1800, and hence has been denominated the Voltaic pile. The apparatus first made by Volta, consisted of a certain number of pairs of zinc and silver plates, separated from each other by pieces of wet cloth ; the arrangement being as follows: zinc, silver, wet cloth ; zinc, silver, wet cloth, and so on. The silver plates were chiefly silver coins, the plates of zinc and the pieces of cloth being of the same size. He found this pile much more powerful when the pieces of cloth were moistened with a solution of common salt instead of pure water, and an apparatus consisting of ſorty pairs of plates, he found to possess the power of giving a very smart shock, similar to that of a small electric jar; and that this effect took place as often as a communication was made between each end of the pile, and as long as the pieces of cloth remained moist. - An account of this discovery was communicated to the Royal Society, and published in the Philosophical Transactions. Since this time we have no account of any farther discoveries of Volta; but the science of Galvanism has been since con- siderably extended by the researches and experiments of philosophers in France, England, and other countries. - The first experiments made on the pile in this country were performed by Messrs. Nicholson and Carlisle, who observed, that on bringing the wires from each end of the column in con- tact with a drop of water, bubbles of some elastic gas were disengaged, which, on closer examination, they found to be hydrogen gas; this discovery gave rise to a great variety of experiments, and to many interesting results, but being chiefly chemical, we cannot here enter into their details. . . . The Galvanic energy evinced in the decomposition of bodies, which the experiments of Nicholson and Carlisle had first made known, was farther prosecuted by Mr. Cruikshank, of Wool- wich, to whom we are indebted for the invention of the Galvanic trough, which we have described under the article Galvanic BATTERY. This again led the way to other batteries of similar construction, but of a more powerful nature, by which it was found, that all the metals reduced into thin leaves were deflagrated with brilliant, though differently coloured flames; and henceforth Galvanism, which had not before assumed any particular character, it being doubtful to what branch of science it properly belonged, was directed entirely to chemistry, and has since been the means of throwing great light on tha interesting-branch of human knowledge. , * * . G. A. L. G. A. L. 351. DICTIONARY OF MECHANICAL SCIENCE. The Laws of Galvanie Combination.—The conductors of elec- tricity are divided into two principal classes. The first class, called dry and perfect conductors, are metallic substances and charcoal, Those of the second class, or the imperfect conduc- tors, are water and other oxidating fluids. . But as the sub- stances of the second class differ in conducting power much more than those of the first class, so they may be subdivided into species. - - - - - Imperfect Conductors.--It may be observed, that water hold- ing in solution common air, and especially oxygen gas, is much more active than water deprived of air by boiling. 2. Water mixed with clay or chalk; 3d, a solution of Sugar; 4th, alco- hol; 5th, milk; 6th, mucilaginous fluids; 7th, animal gelatinous fluids; 8th, wine; 9th, vinegar, and other vegetable juices, and acids; 10th, saliva; 11th, mucus from the nose ; 12th, blood; 13th, brains; 14th, solution of salt; 15th, soap-suds; 16th, chalk water; 17th, concentrated mineral acids; 18th, strong alkaline leys; 19th, alkaline fluids; 20th, sulphuret of potash. Simple Combinqtions of Galvanic Conductors, capable of pro- ducing effects, must consist of three different conductors, for two produce no effect. - - One conductor must 2, be of one class, and ºft the two other con- ductors different of the other class. De- noting the bodies of the first class by means of three capi- tal letters, and those of the second class by small letters, the combinations of No. 1 and 2 are active, but those of 3, 4, 5, are not active ; because they consist of two bodies only, and those of figs. 7 and 8 consist of three bodies; of which two are of the same sort, and of course act as a single body. - - t ºw When two of the three bodies are of the first class, and one of the second, the combination is said to be of the first order; otherwise, it is said to be of the second order. In a single active galvanic combination, or, as it is commonly called, a simple galvanic circle, the two bodies of one class must touch each other in more than one point, at the same time that they are connected together at other points by the body of the other class. Thus, when a prepared frog is convulsed by the con- tact of the same piece of metal in two different places, then the fluids of those parts, which must be somewhat different from each other, are the two conductors of the second class, and the metal is the third body on the conductor of the first class. If two metals are used, then the fluids of the prepared animals differing but little from each other, may be considered as one body of the second class. Thus also, when a person drinks out of a pewter jug, the saliva or moisture of his under lip is one fluid or one conductor of the second class, the liquor in the jug is the other, and the metal is the third body, or con- ductor of the first class. - - It seems to be indispensably requisite, that in a simple galvanic circle, the conductor or conductors of one class should have some chemical action upon the other conductor or con- ductors; without which circumstance the combination of the three bodies will have either no galvanic action at all, or a very slight one. Farther, the galvanic action seems to be pro- portionate to the degree of chemical agency; which seems to shew, that such chemical action is the primary cause of the electric phenomena. The most active galvanic circles of the first order, are, when two solids of different degrees of oxid- ability are combined with a fluid, capable of oxidating at least one of the solids. Thus, gold, silver, and water, do not form an active galvanic circle; but the circle will become active if a little nitric acid, or any fluid decomposable by silver, is mixed with the water. . . * - - ... A combination of zinc, silver, and water, forms an active galvanic circle, and the water is found to oxidate the zinc, pro- vided the water holds in solution some atmospherical air, as it commonly does, and especially if it contains oxygen gas. But zinc, silver, and water, containing a little nitric acid, form a ‘more powerful galvanic circle, the fluid being capable of acting both upon the zinc and upon the silver. The most powerful galvanic combinations of the second order are, when two con- ductors have different chemical actions on the conductors of the first class, at the same time that they have an action upon each other. Thus, copper, silver, or gold, with a solution of alkaline sulphuret, and diluted nitrous acid, form a very active galvanic circle. The present state of knowledge relative to this subject, does not enable us accurately to determine the particular powers of all sorts of galvanic combinations: the , following lists, however, contain an useful arrangement of the best combinations, disposed in the order of their powers, and commencing with the most powerful. Table of Galvanic Circles of the First Order.—These circles consist of two conductors of the first class, and one of the second. 1. Zinc, with gold, charcoal, silver, or copper, tin, iron, or mercury, and water containing a small quantity of any of the mineral acids. 2. Iron, with gold, charcoal, silver, cop- per, or tin, and a weak solution of any of the mineral acids, 3. Tin, with gold, silver, or charcoal, and a weak solution of any of the mineral acids. 4. Lead, with gold or silver, and a weak acid solution. 5. Any of the foregoing metallic combinations, and common water. 6. Copper, gold, silver, and a solution of nitrate of silver and mercury, or nitric or acetous acid. Galvanic Circles of the Second Order, consist of one conductor of the first class, and two of the second. Charcoal, copper, silver, lead, tin, iron, or zinc, with water, or a solution of any hydrogenated alkaline sulphurets, capable of acting on the first three metals, only, and a solution of nitrous acid, or oxygenated muriatic acid, capable of acting upon metals. Theory of the Action of Galvanic Circles.—The action of a single galvanic circle depends on the quantity of surface in contact between the acting bodies; and a high temperature is favourable to this activity. If a circle consist of gold, zinc, and water, the interposition of iron or silver, or both, does not alter the activity. Hence it appears that the action of a gal- vanic circle may be conveyed through extraneous conductors to a considerable distance; but it must be observed, that the activity is weakened by the great length of the conductors, especially if they are of an imperfect nature. - When the three bodies which form a galvanic circle of the first order are laid one upon the other, so that the lower and upper ones do not touch each other, then these two cxtremes are in opposite electric states, viz. the extremity which is next to that metallic surface that touches the body of the second class is positive, and the opposite extremity is negative. Thus, let copper, zinc, and moistened leather, be laid one upon the other, as in the annexed figure, and the upper * > end W, viz. the moistened leather, will be found possessed of positive electricity; whilst the lower end C, or the copper, will be found negative. - - Galvanic Batteries.—Galvanic effects may be increased to almost any degree, by connecting several of the above-men- tioned active combinations, or by a repetition of the same simple galvanic combination, (the most active simple combi- nation forming the most powerful batteries, and vice versa,) provided the simple combinations are disposed so as not to counteract each other. Those batteries are said to be of the second or first order, according as the simple combinations of which they consist are of the first or second order. Example. Thus, if a piece of zinc is laid upon a piece of copper, and a piece of moistened card upon the zinc, then a similar arrangement of three other such pieces laid upon them, and a third arrangement upon this, &c. all in the same order, the whole will form a battery of the first order. But if the arrangement is made by connecting a piece of copper with a piece of cloth moistened with water, the latter with a piece of cloth moistened with a solution of sulphuret of potash, and this again with another piece of copper, &c. the whole will form a battery of the second order. - Sir Humphry Davy divides the batteries of the second order into three classes: first, the most feeble, in which metallic plates are so arranged that two of their surfaces or ends oppo- site to each other are in contact with different fluids, one capable and the other incapable of oxidating the metal. 2dly. 352 G. A. L. G. A. L. DICTIONARY OF MECHANICAL SCIENCE. When simple combinations consist of a single plate, each capable of being acted upon by sulphuretted hydrogen, a solu- tion of sulphuret of potash being on one side, and water on the other. 3dly. Metallic substances oxidable in acids, and capable of action on solutions of sulphurets. Laws of Galvanic Action.—The parts of a battery must not counteract each other. Every simple, but interrupted galvanic combination, has a positive and a negative end, i. e. the elec- tric fluid circulates in one way only. - Fig. 1, Fig. 2. Example. Thus, if two simple combinations are disposed, as in fig. 1, this arrangement will not have any galvanic power, because the actions of the two simple combinations, or the two currents of electricity, are opposed to each other, the two positive ends being called P, - and the two negative ends N. But if those fixed bodies are disposed as in fig. 2, then the combination will be very active, because, according to the hypothesis, the direction of the elec- tric fluid in each simple arrangement tends the same way, and probably the one accelerates the other. What has been said of the above arrangements of the two simple galvanic combinations, must be likewise understood to hold good with respect to the connexion of any number of the same, viz. that they must not counteract each other: or if a certain number of them counteract each other, then the remain- ing only form the active part of the battery. For instance, if a. battery consists of forty simple combinations, and if twelve of them are placed in a direction contrary to the others, then these twelve will counteract twelve others, and of course the whole battery will have no more power than if it consisted of sixteen combinations properly disposed. This points out a method of comparing the powers of two batteries; for if those batteries are connected in an inverted order, viz. the positive end of one to touch the negative end of the other; then on connecting the two other extremities, or on applying them to proper instruments, the whole power will be annihilated, if the separate batteries had equal power; other- wise the power of the whole will be the excess of the power of the most powerful battery above that of the weakest; and the direction, viz. its being positive or negative, will shew to which battery it belongs. It must be observed, with respect to the inactive arrangement of figure 1, that if one of the separate bodies Z, is removed, then the remaining five bodies will form an active combination, for in that case W W become one body, and SS likewise act as one body. Construction of Galvanic Batteries.—When three bodies are selected for the battery, the operator has only to make their contact perfect, and the batteries may be of the forms repre- sented by figs 1, 2, 3. Those of figs, 1, 2, are more easily con- structed; that of *; 3, however, is the most commodious. ig. 1. - |ſ|| Hi | # : : The battery fig. 1, con- |#i # sists of several glasses or ####3 China cups full of water, - º, or of water containing # salt, &c. A plate of zinc É: and a plate of silver are # plunged into the fluid of ||ÉÉ each cup, excepting th ###### first and last cups; but r each of those plates must have a sort of tail or prolongation, by which they are so connected that the silver plate of one cup communicates with the zinc plate of the next, and soon. The battery fig. 2, consists of pieces of silver about the size of half- crowns, pieces of zinc of about an equal size to those of the silver, and pieces of card or cloth, leather, or other bibulous substance, a little smaller in diameter than the metallic pieces; and soaked in water or in any other proper fluid. These pieces are dis- posed in the order silver, zinc, and wet cloth, as indicated by the letters S, Z, W. The pieces of card or cloth, &c. must be well soaked in the fluids; but before they are applied, they should be squeezed, in order that the superfluous fluid may not run down the outside of the pile, or insinuate itself between the contiguous pieces of silver and zinc. Those pieces especially, if soaked in common water, lose their mois- ture pretty soon, so that they can hardly serve longer than for a day or two ; after which time the pile must be deranged, the metallic pieces cleaned, those of cloth or card soaked again, and the whole arranged as before. The three rods, R, R, R, are of glass or of baked wood, and the piece of wood, O, slides This serves to prevent the falling to be very powerful, Fig. 4. freely up or down the rods. of the pieces. When such a battery is that is to say, when it is to consist of numerous pieces, the best way is to form t two or more piles, and to join them by pieces of metal, as C C, in fig. 4, where two piles are joined together, so that a is “iº the negative extremity, and b is the posi- tive one of the whole arrangement, or of . the two piles, a considered as one. The ### battery, fig. 3, consists of a strong oblong #% vessel of baked wood or porcelain, about iſ three inches deep, and as much broad. In the side of this vessel grooves are made opposite to each other, and about = one-eighth of an inch in depth. In each pair of opposite grooves a double metallic plate, viz. a plate of zinc and a plate of silver soldered together at their edges, are cemented, or the plates may be put in, connected only at their upper ends; by which means the wooden vessel is divided into several cells or partitions, about half an inch wide, as is indi: cated by the figure. The cementation of the metallic pieces into the sides and the bottom of the wooden vessel, must be so accurate as not to permit the passage of any fluid from one cell into the next. The cement proper for this purpose, is made by melting together five parts of resin, four parts of bees- wax, and two parts of powdered red-ochre. Those cells are afterwards filled almost to the top with water, or any other fluid, according to the foregoing table, and thus the whole will form a battery, consisting of various repetitions of silver, zinc, and fluid. Two or more of such batteries may be joined, as was said of the preceding battery. - It need hardly be observed, that instead of zinc, copper, and water, other combinations may be made according to the table. At present, the last described batteries are constructed with copper, zinc, and water mixed with a small portion of nitric or muriatic acid. For the construction of such batteries it is of little consequence whether the materials are pure or slightly alloyed. The action of all these batteries is greatest when they are first completed or filled with any fluid ; and it declines | in proportion as the metal is oxidated or the fluid loses its | power. Hence, after a certain time, the fluid must not only be changed, but the pieces must be cleaned, by removing the oxi- dated surface, which is done either by filing or rubbing them with sand, or sand paper, or by immersing them for a short time in diluted muriatic acid, and then wiping them with a coarse cloth. The metallic pieces of fig. 4, may be cleaned by the last method, and wiped by introducing a stick with a rag into the cells. The energy of galvanic batteries, when the troughs are porcelain, may be restored by merely lifting out the metals, and exposing them to the action of the atmosphere. This much may be sufficient with respect to the construction of simple and compound galvanic arrangements. - Galvanic Experiments.—Experiment 1. When the galvanic battery of the first order consists of twenty repetitions of sim- ple combinations, and if with one hand one extremity of a battery be touched, and the other hand be applied to the other extremity of the battery, a shock will be felt, like that which is communicated by a Leyden phial weakly charged, and it will hardly be felt beyond the fingers, or at most the wrists. This shock will be felt as often as the contact is repeated. - G. A. L. G. A. M. 353 DICTIONARY OF MECHANICAL SCIENCE. Note,—The battery in the following experiment, is the form of that most usually sold by the philosophical instrument makers. The nitric and muriatic acid may be had at any chemist’s shop. - - - - - 2. If the hands are continued in contact with the extremities band a, a slight but continued irritation will be perceived; and when the hand which touches the extremity of the battery is excoriated or wounded, this sensation is disagreeable, and g rather painful. (?, % ºn tº (well moistened with water,) and on completing the circuit, they will all feel the shock at the same instant. But the strength of the shock is much diminished, by its passing through the several persons, or, in general, by passing through less perfect conductors. . - - 4. The shock from a battery consisting of fifty or sixty repe- titions, of the most active combinations of the first order, may be felt as far as the elbows, and the combined force of five or six such batteries will give a shock much stronger, perhaps, than most men would be willing to receive. The prepared limbs of a frog or other animal are violently convulsed; but soon exhausted of their irritability by the action of a galvanic battery, and its action on a person lately executed at Glasgow was the most singularly terrific that medical practitioners had ever witnessed. 5. If a wire, proceeding from one extremity of a pretty strong battery, is made to communicate with the inside coat- ing; and a wire which proceeds from the other extremity of the battery is made to communicate with the outside coating of a common large jar or electrical battery; the latter will become weakly, but almost instantaneously, charged in the same manner as if it had been charged by a few turns of a common electrical machine; with this charge you may either give the shock or effect on the electrometer. 6. The spark, or the discharge of a galvanic battery, when sent through thin inflammable bodies that are in contact with common air, or oxygen gas, sets them on fire and consumes them with wonderful activity. It fires gunpowder, hydrogen gas, phosphorus, and other combustibles ; it renders red-hot, fuses, and oxidates very slender metallic wires, and metallic leaves. The mode of applying the power of the battery for such purposes, is shewn in fig. 2, where Fig. 2, A B represents a powerful galvanic bat- tery; A C D F, is a wire which commu- c nicates with the last plate of the battery at A : B K H G is another wire which communicates with the last plate at B. DE, HI, are two glass tubes, through which those wires pass, and into which they are fastened sufficiently steady. These tubes serve to move the wires; for if the operator applies his fingers to those tubes, he may move the wires wherever he pleases, without the fear of receiving a shock. . If the two extremities FG, are brought sufficiently near to one another, the Spark will be seen between them. It is between those extremitiés that the combustible substances, or the metallic leaf, is to be placed in order to be fired or burned. This figure, moreover, represents the situation of the wires in the act of inflaming gunpowder. 7. A battery consisting of 200 pairs of metallic plates (viz. copper and zinc, each five inches square) melted 23 inches of yery fine iron wire. A platina Fig. 3 wire about tº inch in diameter, 9. 3. was melted into a globule. Fig. 3, is the representation of a compound battery of the same kind, fastened together with iron Cramps a, b, c. Under the exhausted receiver of the - air pump, the galvanic battery - - acts less powerfully than in the open air; but in oxygen gas, it acts with increased power, - Fig. 1. 42. * . . * * \º Ç% sº } 8. The flash of light, which appears before the eye of the experimenter, when the eye itself or some other part not very remote from it, is put in the circuit of a galvanic combination, does not appear much greater when a battery is employed than when two plates are applied in the manner which has been already mentioned; but when the battery is used, the sensation of a flash may be produced in various ways. If one hand or both be placed in contact with one extremity of the battery, and almost any part of tho face brought into contact with the other extremity, the flash will appear very distinctly, the experimenter being in the dark, or keeping his eyes shut. This flash appears very strong, when a wire which proceeds from one extremity of the battery, is held between the teeth, and rests upon the tongue, whilst the other wire is held in the hand. In this case, the lips and tongue are convulsed, the flash appears before the eyes, and a very pungent taste is per- ceived in the mouth. - 9. If any part of the human body, forming part of the circuit of a galvanic battery, is kept sometimes in that situation, the irritation is more or less distinct, according to the sensibility of the parts concerned. This application is likely to prove most useful as a remedy in various disorders. It is said, that it has already proved most beneficial in deafness and in rheumatisms. Decomposition of Compound Bodies.—The most extraordinary phenomena of galvanic batteries, are the chemical effects pro- duced upon bodies placed in a circuit. Thus, when into two small tubes, connected by a moist animal substance, and filled with distilled water, two gold wires are introduced from a large battery in the proper order, oxygen is produced in one quantity of water and hydrogen in the other, nearly in the pro- portions in which they are required to form water by combus- tion. All the oxygenated solutions of bodies possessing less affinity for oxygen than nascent hydrogen, are decomposed when exposed to the action of the metal occupying the place of the least oxidable part of the series in the compound circle. Thus we may produce sulphur from sulphuric acid; and preci- pitate copper and other metals in the metallic form, from their solutions. On bringing potash and soda within the action of a powerful battery, Sir H. Davy found that metalline substances were produced, which he has named potassium and sodium. . It is well known, that hydrogen in its nascent state, reduces the oxide of metals. Accordingly, when a tube is filled with a solution of acetate of lead in distilled water, and a communi- cation is made with the battery, as above described, no gas is perceived to issue from the wire which proceeds from the negative end of the battery; but, in a few minutes, beautiful metallic needles are perceived on the extremity of this wire; they soon increase, and assume the form of a fern leaf, or other vegetable. The lead thus separated, is in its perfect metallic state, and very brilliant. When a solution of sulphate of cop- per is employed, the copper is precipitated in its metallic state; but instead of appearing in crystals, it forms a kind of button, which adheres firmly to the end of the wire. The effects of the galvanic battery upon the human frame when dead, are extraordinary, but of these we cannot now treat. Improvement in the Galvanie Battery.-Professor Oersted, among his other discoveries on the affinity between electricity and galvanism, has ascertained the important fact, that to pro- duce an active influence on the magnetic needle, and divert it from its position, exposing it to the action of a single pair of discs of copper and zinc, separated by a conducting body, will be sufficient; and that this simple apparatus will act with more force than an entire pile. By this simplification of the galvanic process, he has suspended two plates of copper and zinc sepa- rated by a liquid conductor, to a very fine thread; and he has found this arrangement competent to give them a higher de- gree of mobility, and to render them susceptible of obeying or yielding to the action of exterior agents however feeble. Little bars, strongly magnetized, presenting either of their poles to the apparatus, repulsed or attracted it, imparting a rotatory movement about the point of suspension. GAMBOGE, a concreted vegetable juice, partly of a gummy and partly of a resinous quality, brought from India. . - GAME, in general, signifies any diversion or sport performed with regularity, or restrained to rules. Games are usually 4 X $54 G. A N G. A. R. DICTIONARY OF MECHANICAL scIENCE. distinguished into those of address and those of hazard. . To the first belong chess, tenis, billiards, wrestling, &c. and to the latter those performed with cards or dice, as backgammon, ombre, picquet, whist, &c. GAMes, in Antiquity, were public diversions, exhibited on solemn occasions. Such, among the Greeks, were the Olympic, Pythian, Nemaean, &c. games; and among the Romans, the Apollinarian, Circensian, Capitoline, &c. games. The Romans had three sorts of games, viz. sacred, honorary, and ludicrous. The first were instituted in honour of some deity or hero: of which kind were those already mentioned, together with the augustalis, doralis, palatini, &c. The second were those exhi- bited by private persons to please the people, as the combats of gladiators, the scenic games, and other amphitheatrical sports. The ludicrous games were much of the same nature with the games of exercise and hazard among us; such were the ludus trojanus, tesserae, tali, trochus, &c. GAME. It is a maxim of the common law, that goods of which no person can claim any property, belong to the king: hence those animals, (ferae naturae,) which come under the denomination of game, are styled in our laws his majesty’s game; and that which he has, he may grant to another; in consequence of which, another may prescribe to have the same within such a precinct or lordship. And hence originated the right of lords of manors, or others, to the game within their respective liberties. For the preservation of these species of animals, for the recreation and amusement of persons of for- tune, to whom the king has granted the same, various acts of parliament have been made. To entitle any one to kill game, he must now take out a certificate, upon which a stamp duty is payable. There are innumerable acts of parliament inflicting penalties on persons illegally killing game, and some of them exceedingly severe, extending even to transportation. Yet, whilst so many persons of great wealth have not otherwise the means of procuring game except by purchase, and are desirous of having it, the encouragement thus given to poaching will continue to render all game laws nugatory as to the effect intended. It is not lawful for qualified persons to kill game at all seasons. The time for sporting, in the day, is from one hour before sun - rising, until one hour after sun - setting. 10 Geo. III. c. 10. For bustards, the sporting is from Dec. 1 to March 1. For grouse, or red grouse, from Aug. 11 to Dec. 10. Hares may be killed all the year under the restrictions, in 10 Geo. III. c. 19. Heath fowl, or black game, from Aug. 20 to Dec. 20. Partridges, from Sept. I to Feb. 12. Pheasants, from Oct. 1 to Feb. 1. Widgeons, wild ducks, wild geese, wild fowls, at any time but in June, July, August, and September. GAMELION, in Ancient Chronology, was the eighth month of the Athenian year, containing 29 days, and answering to the latter part of our January and beginning of February, GAMING, LAws of. These are founded on the doctrine of chances. De Moivre, in his treatise De Mensura Sortis, has computed the variety of chances in several cases that occur in gaming, the laws of which may be understood by what follows. Suppose p the number of cases in which an event may happen, and q the number of cases wherein it may not happen, both sides have the degree of probability, which is to each other as to q. If two gamesters, A, and B, engage on this footing, that if the cases p happen, A shall win; but if q happen, B p a p + q ; hence, if they sell the expectancies, shall win, and the stake be a ; the chance of A will be and that of B _T * p + q they should have that for them respectively. See CHANces. GAMMONING, seven or eight turns of a rope, passed over the bowsprit, and through a large hole in the stem or knee of the head, alternately, and serving to bind the inner quarter of the bowsprit close down to the ship's stem, in order to enable it the better to support the stays of the foremast; after all the turns are drawn as firm as possible, the opposite ones are braced together under the bowsprit by a frapping. GAMUT, or GAM-UT, in Music, a scale on which we may learn to sound the musical notes ut, re, mi, fa, sol, la, in their several orders and dispositions. GANG, a select number of a ship's crew appointed on any ..length of the floor. particular service, and commanded by an officer suitable to the occasion. . -- GANG Board, a plank or board, with several cleats or steps nailed to it, for the convenience of walking into or out of a boat upon the shore, where the water is not deep enough to float the boat close to the landing place. - GANG, or Gangue, in Mineralogy, is a word used by German mineralogists to denote a metallic vein. But according to the French, it denotes the stony matter which accompanies the ore in the vein. GANGRENE, is a great and dangerous degree of inflam- mation wherein the parts begin to be in a state of mortification. GANGWAY, a narrow platform, or range of planks, laid horizontally along the upper part of a ship's side, from the quarter deck to the forecastle, and is peculiar to ships that are deep waisted, for the convenience of walking more expedi- tiously fore and aft, than by descending into the waist: it is fenced on the outside by iron stanchions, and ropes or rails, and in vessels of war with a netting, in which part of the ham- mocks are stowed. In merchann Ships, it is frequently called the gang-board. GANGw AY, is also that part of a ship's side, both within and without, by which persons enter and depart; it is provided with a sufficient number of steps, or cleats, nailed upon the ship's side, nearly as low as the surface of the water, and some- times furnished with a railed accommodation ladder, resembling a flight of stairs projecting from the ship's side, and secured by iron braces. GANGw AY, is also used to signify a narrow passage left in the hold, when a ship is laden, in order to enter any particular place as occasion may require, whether to examine the situa- tion of the provisions or cargo ; to discover and stop a leak, or to bring out any article that is wanted. Finally, Gangway implies a thoroughfare, or narrow passage of any kind. To bring to the GANGw AY, a phrase signifying to punish a seaman by seizing him up and flogging him with a cat-o'-nine- tails GANTLOPE, or GAUNTLope, vulgarly pronounced Gantlet, a race which a criminal is sentenced to run in a vessel of war, for felony, or some other heinous offence. It is executed in the following manner:—The whole ship's crew is disposed in two rows, standing face to face on both sides the deck, so as to form a line whereby to go forward on one side and aft on the other, each person being furnished with a small twisted cord called a hwittle, having two or three knots upon it; the delinquent is then stripped naked above the waist, and ordered to pass forward between the two rows of men on one side and aft on the other side, a certain number of times, rarely exceed- ing three, during which every person gives him stripes as he runs along; in his passage he is sometimes tripped up and severely handled while incapable of proceeding ; this punish- ment, which is called running the gantlet, is seldom inflicted except for such crimes as naturally excite general antipathy amongst the seamen. GARBOARD-STREAK, the first range or streak of planks laid upon a ship's bottom, next the keel, throughout the whole * The edge of this plank is let into a groove or channel in the side of the keel, which is called the rabbet of the garboard-streak. *… * GARDENING. This art, so natural to man, may be divided into two branches, practical and picturesque. A garden, properly speaking, is a small spot of ground attached to the house. As the house is itself a regular and formal object, so we maturally expect something of the same 'regularity in this appendage. Neatness too is one of the chief excellences of a garden, and this is wholly inconsistent with a rage for the pic- turesque. See Loudon’s CYCLOPEDIA of GARDENING. The situation of a garden should be dry, rather low than high, and sheltered from the north and east winds. These points of the compass should be guarded against by a wall ten feet high; lower walls do not answer so well for fruit trees. A garden should be so situated, as to be as much warmer as possible than the general temper of the air is without, or ought to be made warmer by the ring and subdivision fences. A garden may be square, but an oblong is preferred, and the area rather a level; or if there is a slope it should, be southward, a G A R G A R 355 DICTIONARY OF MECHANICAL SCIENCE. point either to the east or west not much signifying; but not to the north, if it can be avoided, because crops come in late, and plants do not stand the winter so well in such a situation. A garden with a northern aspect has advantages, being cooler for some summer productions. The best soil for general cultivation is a loam, rather red than black. The worst is a cold heavy clay, and the next a light sand; a moderate clay, however, is better than a light soil, though not so pleasant to work. The aspect of the wall designed for the best fruits may be full south ; or inclining to east, by which it will catch the sun's rays at its rise, the cold night-dews be earlier dissipated, and the scorching rays of the afternoon sun are sooner off. By thus having the walls of a garden not directly to the four points, the north wall is greatly advantaged by having more run. The border next this wall should be of good earth, about two feet deep, rising a little towards the wall. A free mode- rate loam, or some fresh maiden soil, not too light, is essential to make the borders promising good; and in order to this, if manure is necessary, let it be that of rotted vegetables, or turf, with wood ashes; for the roots of fruit-trees should not meet with much dung, at least of horses; that of cows is the best, or that of sheep or hogs will do well rotted, well mixed, &c. being worked in the borders as long as possible before the trees are planted. If a garden is large and square, a second south wall, running down the middle of it, would be useful; and so, if large and Jong, a cross wall or two might be adopted, as giving oppor- tunity for the cultivation of more trained fruit-trees; and if there is any idea of forcing fruits, these intersecting walls, ranging east and west, are proper for it, (as situated within the ring fence,) furnished with flues, &c. The best fruit border being prepared for peaches, nectarines, and apricots, or vines and figs, the trees should take their residence there, (if the leaf is falling,) about the latter part of October. If the middle of December is past, February is then the time; though gardeners plant all winter, if the weather is open enough to work the ground. March, however, may do, or even the beginning of April. } Wall trees should not be older than two years from grafting or budding. Except in fine situations, never plant early and late peaches; as the first may be cut off, and the latter not ripen. The distance to plant should be about twelve inches from the wall: and let apricots, peaches, and nectarines be twenty feet asunder, or according to the height of the wall; though for the small early sorts fifteen or sixteen feet will do. As the larger apricots, however, grow freely, and do not well endure the knife, they ought to have twenty-five feet allowed them. This is for a wall nine or ten feet high; if higher, the distance may be less, and if lower, the contrary. Fig trees require as much room as the apricot, or rather more; as they grow freely, and are to extend without shortening. Though other trees are best planted in October, the fig should not be till March. The intermediate spaces between peaches, necta- rines, and apricots, may have a vine, a dwarf cherry, or currant or gooseberry tree of the early sorts, as the smooth green and small red, to come in early. But wherever grapes can be expected to ripen, there let a young plant or cutting be set, though the space should be confined; for the vine, freely as it shoots, bears the knife well to keep it within bounds. If the wall is high, the cherry or plum may be half-standards; which being after a while kept above, will be more out of the way of the principal trees; though dwarfs may be trained so as not to interfere. Some have planted half-standards of the same kind of fruit as the dwarfs; but whichever mode is adopted, let the intermediate trees be pruned away below in good time, in order to accommodate the principals freely as they mount and extend. Plums, cherries, and pears, may occupy the other walls; the two former at about fifteen feet, or it may be twenty feet asunder. Cherries, except the morella, will not do well in a full north aspect; but any sort of plum (rather a late one) and summer pears, and also nut trees, will, if you choose to train them. There should always be some currants and gooseberries in an east and north situation, at the distance of eight feet, where they will be easily matted, when ripe, to come in late, as October, November, or perhaps December. Pear trees of free growth are hardly to be kept within tolerable compass on low walls; but if attempted, should have at least thirty feet allowed them. The best sorts of winter pears deserve a south- erly wall to ripen them well, and improve them in size and flavour. The gable end of a house is well adapted for a pear- tree, as it affords room, which they require. Apples may do well on a wall, (and if any on a good wall, let it be the golden pippin,) yet the practice is seldom adopted. For furnishing-walls, choose trees of moderate wood, young, well rooted, clean, and healthy. When the planting of a garden is finished, it will be a good way to have a plan of it taken, with the name of every pecu- liar tree marked on it in its place, to be assured of the sorts when they come to bear. Here it may be observed, that if any evergreen hedges are desired in or about the garden, yew, box, alaternus celastrus, philly rea, and pyracantha, may be kept low, and clipped in form, if so desired; in addition to which, if a few roses were intermixed, it would have a very pretty effect. A deciduous hedge for subdivision, or screen, &c. may be made of elms or limes, setting the larger plants at five feet asunder, and a smaller one between. Or an ordinary fence, or subdivision, may be quickly formed of elder cuttings, stuck in at two feet asunder, which may be kept cut within bounds. A wide body next the south wall, as was said, is best for the trees; and moreover, for the many uses that may be made of it for the smaller early, or late tender esculents, and a few earlier cauliflowers. For the sake of a pleasant warm walk in Spring, to have the south border narrow may be desirable; but on no account let it be less than six feet. Take care that this walk is not sunk too much; and that it have a bottom of good earth, as deep as where the trees are planted. Let the body of gravel be thin, and then the roots of the trees will be admitted to run properly under the walk, and find wholesome nourishment; where, if they were stopped by rubbish, they would be apt to canker, and irrevocably disease the trees. The number and breadth of the walks must in a measure be determined by the quantity of allotted ground; exceeding in these particulars where there is room. But few and wide walks are better than many and contracted. If edgings are to be made, in order to separate between the earth and gravel, especially if of stone or wood, or box, they should be done first, and they will be a good rule to lay the box by. Grass walks may answer where gravel is scarce. Camomile has been also used to form green or carpet walks, planting it in sets about nine or ten inches asunder; which naturally spreading, the runners are fixed by walking on them, or rolling. Sand may be adopted for walks, but lay not any of it too thick, as it is the less firm for it. Coal-ashes stre wed thinly in the alleys are better than nothing, as they at least serve to keep the feet dry. Sea-shells make very good walks. . All trees designed to be planted are to be thought of before winter. Those of the wall have been spoken of; and as to standards, they must have a fair depth of good soil to grow in ; for it should be remembered, that tree roots in a garden are prevented from running over the surface, as they do in an •undisturbed orchard. It is necessary that some caution should be used not to dig the ground too near and too deep about garden trees, lest, loosening the roots, they should not be able to stand the wind; and because the nearer the surface any root grows, the more and choicer fruit the tree bears. But the fewer standard trees in a garden the better, as they take up . much room, and by their shade prevent the proper growth of vegetables that are near them; so that if a garden is small there should be no trees except those of the wall. The case is different where there is ample room; and the blossoms of fruit trees are so delightful, that if they produced nothing for the palate, there would be a sufficient inducement to plant them for ornament; but let them be dwarf standards in preference to espaliers. Dwarf standards occasion less trouble to keep them in order than espaliers, and are generally more productive; for espalier trees are seldom managed well, and thus appear unsightly: at best they are stiff and formal, and obstruct the sight in viewing the quarters of a garden, which, if in order, are worthy of coming | under the eye. G A R. G. A. R. DICTIONARY OF MECHANICAL SCIENCE. * If any espaliers are planted, let them be only fruit of the best sorts, and in spacious gardens, where they may have a good length and height allowed them to grow freely. They should rather be trained to sawed materials properly framed together, smoothed and painted. But for a year or two they may be fastened to light stakes, when they will have formed a head, to begin to train them for bearing in the neat manner proposed, that is, to slips of deal joined to light oak posts, as trellises. Whether the slips are placed perpendicularly or longitudinally, seems indifferent. If the longitudinal mode of training is the best approved, strong iron wire may be recommended to run through the posts instead of slips of wood, as it shades less, and is stronger and neater. should be slender, and from six to eight inches distant, accord- ing to the greater or less freedom of the natural growth of the tree. Apples should be allowed 24 feet, and 'pears 30, except those grafted on paradise or quince stock, for which little more than half this distance may answer. Cherries and plums should have about 18 or 20 feet allowed them. Quinces, med- lars, mulberries, and filberds, may also be espaliered. The trees should be planted about a yard from the edge, but farther off is better, if the walks lie deep of gravel or poor materials. Currants, gooseberries, and raspberries, do well espaliered, as to a production of early and fine fruit. Trees of a more humble nature, and shrubs, next occupy attention in furnishing a garden. Currants and gooseberries (as bushes) should be planted three feet from the edge, and full six feet asunder. Some of these very useful shrubs should grow in every aspect of the garden, in order to have a succes- sion of their fruits as long as may be. Those who choose to plant whole quarters of currants and gooseberries, ought to do it at six feet asunder in the rows, and the rows eight feet from one another. x. Raspberries may be set in plantations, in rows five feet asun- der, allowing three feet between the plants. These shrubs are always best by themselves, as otherwise their suckers over-run the quarters. Between rows of raspberries planted at the above distance, coleworts, early cabbages, cauliflowers, and lettuces may be set, or spinach sowed in drills; the raspberries having had their pruning and dressing early in autumn for the purpose. Every year, a little short manure, dug in close about the roots, (and deeper as the plantation gets older,) will ensure fine fruit. Raspberries are not very nice as to soil and situation. The smooth-wooded or cane-rasp is to be preferred for a principal crop. The large, white, or Antwerp, is also good. Strawberries may be planted at the edges of borders and quarters, either in single or double rows, (rather the latter) for the convenience of gathering, and for ornament, but the com- mon and best way is, in four-feet beds, with eighteen-inch or two-feet alleys, on which beds may be five rows of the wood and alpine, four of the scarlet and pine-apple, three of the Carolina, and two of the Chili; setting the plants at the same distance in the rows as the rows are from one another in the quincunx order. In a good, cool, loamy soil, which suits them best, a little more distance may be allowed the first four sorts; and in a quite dry light soil, somewhat less, that they may shade one another the better from drought. The best situation for strawberries is an open and sunny one, as thus they bear more and finer-flavoured fruit. Some of the scarlets should be planted under warm walls, to come early. The woods bear shade as natural to them, and the alpines do tolerably well in it. The most proper time for planting thc strawberry is the first moist weather in September, (or even earlier,) that they may be established in the ground before winter, and they will bear the better the first year. Frost is apt to throw up late-planted ones, and injures if not destroys them. spring often suffer from drought, and bear very little the first year, except the alpines. Choose forward runners for plant- ing, and let them be from beds in full bearing, that is, of two or three years old, for plants from old beds are not so fruitful. Press the mould to the roots, give them a watering, and again once or twice if the weather proves dry. Some gardeners let them run over the beds, which in a dry light soil may be proper; but in this case, a greater distance should be allowed If upright slips are used, they Those planted in * them at planting. If the alpine sort is planted on a warm border, eighteen inches asunder, and suffered to spread, the first runners will fruit the same year, and sometimes this prolific strawberry bears till November. - Fresh plantations of strawberries should be made every fourth year, though in a good soil, and with good management, they will continue longer; so that where they are suffered to run, the plants being frequently renewed, and old ones removed, beds have borne tolerably for ten years. The watering of strawberries should not be neglected, doing it almost daily when in flower, and setting their fruit, if the weather proves dry, particularly to those under a warm wall; but this is not to be continued when the fruit is nearly ripe. Flowering shrubs may be dispersed about, and herbaceous perennial flowers; but plant them not too near the edge, lest they hang over the walks. The bulbous sort may, however, be within six inches, especially crocuses and snow-drops. Asparagus and artichokes take up much room, and in small gardens may therefore be left out. It will be of little use to have less than 50 or 60 feet of asparagus-beds, as there would be so few heads to cut at a time; and artichokes must be planted wide. Let not potherbs be forgotten, but provide a general herbary in that part of the garden which is warmest, and best shaded, for these are tender plants. Having spoken of stationary things, the routine of the Seasons must dictate the rest; and the inclinations of the palate will refresh the memory to take care of providing the most necessary and agreeable esculents for dressing, and raw salads. - Perennial flowers have been mentioned; but let fancy direct as many annuals and biennials to be cultivated, as room can conveniently be found for, that the garden may be as much as possible ornamented. In furnishing a garden with shrubs and flowers, respect should be had to their usual height, their bulk, colour, and season, that the mixture may be properly varied, harmo- nious to the eye, and come in regular succession. The latter part of the year is seldom provided for so well as it might be ; late flowers should be set in warm situations, as their proper place. In the most dreary months, by judicious planting, evergreens in their neat and cheerful “winter liveries,” may be viewed from our windows, and serve instead of flowers. Those who garden upon a large scale, should take care to have every thing proper and convenient liberally provided. Let there be a well-situated place for hot-beds, with some building as a tool house, and (if dry) for keeping bulbs, seeds, and herbs. Those also who garden even upon a small scale, will do well to have every needful implement. If water can be introduced and kept clean with verdant banks around it, it would be found very useful where a garden is large; but let it be as near the centre as possible, as the most convenient situation. It should be fed from a pond in preference to a Spring. Mixed gardening, as comprehending the profitable with the pleasant, has been the subject hitherto ; but if the flower gar- den and the kitchen garden are to be distinct, the case is altered ; not so much indeed, but that still the kitchen garden should be adorned with a sprinkling of the more ordinary decorations, to skirt the quarters, chiefly those of the most powerful sweet scents, as roses, sweetbriars, and honeysuckles, wall-flowers, stocks, pinks, mignonet. * The Flower-garden, properly so called, should be rather small than large; and if a separate portion of ground is appro- priated for this, only the choicest flowers should be introduced, and cultivated in the best manner. The beds of this garden should be narrow, and consequently the walks numerous; and not more than one-half or two-thirds the width of the beds, except one principal walk, all round, which may be a little wider. The gravel, or whatever the walks are made of, should lie about four inches below the edge. The beds for tulips, hyacinths, anemones, ranunculuses, &c. may be three and a half or four feet wide, and those for single flowers the same, or only two and a half feet wide in the borders. Let the beds lie rather rounded in the middle, but the walks flat. Figured parterres have got out of fashion, as a taste for open and extensive gardening has prevailed; but when the beds are not C. A. R. G. A. R. DICTIONARY OF MECHANICAL SCIENCE. 357 too fanciful, but regular in their shapes, and chiefly at right angles, after the Chinese manner, an assemblage of all sorts of flowers, in a fancy spot of about 60 feet square, is a delightful home source of pleasure, worthy of pursuit. There should be neat edgings of box to these beds, or rather of neat inch boards, painted lead colour, to keep up the mould. Be sure to, keep the box from the very first, as soon as rooted, and always after, as low as possible; clip it twice a year, April and July. - . Landscape or Picturesque Gardening, is so much the work of fancy, and so much depends upon the situation, or what Brown and . Loudon call the capability of the place, that that no precise rules can be laid down concerning it, . All, therefore, that can be expected, is a few loose hints, on which the man of taste may improve according to circumstances. The pleasure we seek in laying out gardens, is now justly founded upon the principles of concealed art, which appears like nature; but still, whether ingenious contrivances, and decorations, (altogether artificial,) should be so entirely laid aside as they are, may deserve to be considered., Perhaps the works of the statuary might still be introduced, if well executed, and in proper places. A terrace, as a boundary, is now seldom formed, but in some situations such an eminence might in several respects be agreeable. - If trees are planted injudiciously, the error is a trifle, but if cut down so, the consequence is serious, and has often been sorely lamented; extirpation should therefore be well thought of before it is executed, especially trees about houses, for many dwellings have been thus too hastily exposed, and deprived of comfortable shelter and shade. Hilly spots that are in view of the house should be planted with firs, as fine looking trees, and very hardy. Beech does well on high ground, especially if chalky. In low ground, not to mention alders, and that tribe, the birch, and even the oak, should not be forgotten, where the wet does not long stand. • * About the house some shady walks ought always to be pro- vided, by thick planting, if not of trees, yet of flowering shrubs, and evergreens, of which the laurel will be found the most useful. Those who have much space of ground to decorate, do well to plant trees, and shrubs of every kind, as enlarging the sources of amusement: but if the allotment of ground for this purpose is contracted, then, of course, those only should be planted which by their neat foliage, natural symmetry, and gay flowers, may be truly esteemed ornamental. The walks should always be wide, some inclining to serpentine, and contrived as much as possible upon a level, as walking up and down hills can hardly be called pleasure. That they may be extensive, they should skirt the grounds and seldom go across them. In small pleasure grounds the edges of the walks should be regu- larly planted with flowers, and long ones occasionally so, or with the most dwarf shrubs; and neat sheltered compartments of flowers (every now and then to be met with) have a pretty effect. If the walks are extended to distant plantations of forest-trees, évery opportunity should be taken to introduce something of the herbaceous flowery kind, which will prove the more pleasing, as found in unexpected situations. The outer walk of pleasure grounds and plantations should every now and then break into open views of the country, and to parts of the internal space, made pleasing, if not striking, by some work of art, or decoration of nature. - Water should only be introduced where it will run itself clear, or may be easily kept so, as also in full sight; and some fall of it should be contrived, (if possible) for the sake of giving it motion and sound, because a lively scene of this element is always much more pleasant than a dead one. Near some pieces of water, as a cool retreat, it is desirable that there should be something of the summer-house kind; or a simple rustic arbour, embowered with the woodbine, the sweetbriar, the jessamine, and the rose. . - Before the design of a rural and extensive garden is put in execution, it ought to be considered, or anticipated what it will be in twenty or thirty years’ time; for it often happens, that a design which looks handsome when first planted, and in good proportion, becomes so small and ridiculous in process of time, that there is a necessity either to alter it or destroy it entirely, and so plant it anew. Landscape gardening depends Ue much on the form of the ground, and therefore to shape that is the first object. Too much plane is to be guarded against; and when it abounds, the eye should be relieved by clumps, or some other agreeable object. Hollows are not easily filled; and eminences mostly are advantageous in the formation of picturesque scenes, in which the general principle of ornamen- tal gardening consists. - To plant picturesquely, a knowledge of the characteristic differences of trees and shrubs is evidently a principal qualifi- cation. To range the shrubs and small trees, so that they mutually set off the beauties, and conceal the blemishes, of each other; to aim at no effects which depend on a nicety for their success, and which the soil, the exposure, or the season of the year, may destroy ; to attend more to the groups than to the individuals; and to consider the whole as a plantation, not as a collection of plants ; are the best general rules which can be given concerning them. - The Cultivation of a Garden.—The first object with a view to produce should be, to keep the ground in such a state as will enable it to produce good crops. Good vegetables cannot be had without good manure. Yet raw unwrought dung is not good for a garden. The most economical plan, therefore, that can be pursued, is for the first year to make good hotbeds of your dung, and spread it out upon the quarters, and dig it in autumn and winter. You by this means have a double pro- duce, and the dung is the better, Dung, however, used in great quantities, and lying in lumps, breeds worms, grubs, and other insects, and causes plants to grow too rampant and rank-flavoured. Carrots it cankers, and it disagrees with many things. On these accounts some persons have been induced to dress their gar- dens only with rich fresh earth. . If the ground is in proper heart, every spot may be contrived to be constantly and successfully cropped, as each sort of plant draws a somewhat different nourishment; so that after a full crop of one plant, one of another kind may often be immediately sown; but it should be contrived that a wide crop may follow a close one, and contrariwise. Close crops, as onions, leeks, carrots, &c. are conveniently and neatly cultivated in beds of from four to five feet width, with alleys of from a foot to eighteen inches between them. : The seasons proper for furnishing the ground with every particular vegetable, should be well attended to, that each may be obtained as early as its nature will permit; and of the seeds and plants we use, care must be taken to procure the best of the kind, lest after all the trouble of cultivation, dis- appointment, as to quality, should ensue. Seeds and plants should be adapted as much as possible to the soil and situation which best suits them. The thinning of seedling crops should be done in time, before the young plants have drawn one another up too much. Ali plants grow stronger and ripen better, when the air circulates freely round them, and the sun is not prevented from an immediate influence. • In the pricking and planting of crops, be sure to do it as early as may be ; let every thing be regular. Shading of new planted things, particularly flowers, is of much benefit, and that in proportion as the season is sunny. Strawberries and cauliflowers are generally watered in a dry season; that is, the strawberries when in bloom, in order to set the fruit, and the cauliflowers when they shew fruit, in order to swell the head. In very dry weather, asparagus seed- lings, early turnips, carrots, radishes, and small salads, will need watering. Slips, cuttings, and layers of any kind, will need water. Pots of flowers must have it frequently. When watering is undertaken, let it be a complete business, i. e. to the bottom and extent of the roots, as much as may be. Wetting the surface of the ground, however, in a summer’s evening, makes a cool atmosphere; a dew is formed, which pervades the leaves, and helps to fill their exhausted vessels. Watering the roots of wall trees, (if dry weather,) when the fruit is setting, is by some thought necessary. To young trees only it can, however, be of use, for the roots of old ones run far and wide; and it is the small fibres of these distant roots on which the tree chiefly depends for food. Vines should have no water till they are off blossom, (July) and ihe fruit as big as large pins' heads; and then, if the season is very hot 358 G. A. R. G. A. R. DICTIONARY of MECHANICAL SCIENCE, and dry, watering the roots twice a week will help the fruit to swell, As watering is apt to make the ground hidebound and unsightly, let the surface be occasionally stirred and raked, which will make future waterings enter the ground the better. Many things are impatient of being kept wet about the shanks, and therefore watering should be generally at a little distance. Rain water is the best for watering, as appears by the verdure and vivacity it gives. Pond water is next in fitness, and river water follows. Well water is of least account, though local circumstances occasion its use the most. Pump water, if used directly, is so cold in summer, that it is found prejudicial to plants; and great cold so contracts their vessels, that they #. their proper offices with difficulty, and become iseased. - The management of a garden, as somewhat distinct from the cultivation of it, is an object of consequence; that is, to keep it in such order, that it may not fail in those general impressions of pleasure it is capable of affording, when things are shewn in their best manner. A garden may be cultivated so as to be profitable, and yet not conducted so as to be agreeable to walk in, which, in a private garden, is a circumstance surely to be lamented. The proper appearance of a well-managed one is expressed by the word meat. Let all be done that can be in order to it. To be neat, weeding must be industriously fol- lowed up, and all litter that is made in working, quickly carried off. The ground also should be frequently stirred and raked between crops, and about the borders, to give all a fresh ap- pearance. There is a pleasantness to the eye in new broken earth; and when there are no flowers left in the borders, this gives an air of culture, and is always agreeable. An asparagus fork is expeditious and useful in this case; but it must be slightly used, lest it disturb the roots of plants too much. Vegetables should not be suffered to rock themselves by wind, so as to form holes round their stems, but be well earthed up, or otherwise supported. Trees and shrubs should be constantly freed from suckers and dangling shoots, and wall-trees ought to be regularly kept In order. Grass plats and walks should have their edges occa- sionally cut, and be mowed as often as there is the Feast hold for the Scythe, for they lose much of their beauty when the grass gets long; leaves should not be suffered to remain on them, as it stains, the grass, and worm-casts should be cleared away. Edgings of all sorts should be kept in good order, as having a singularly neat effect in the appearance of a garden. Some fruits may need support by tying their weak branches when they get heavy, to stakes, &c. Rows of raspberries and beans are kept neatly up in their lines, by putting in here and there a stake, and using packthread lengthwise; and thus will they bear better, and be more conveniently gathered. Straw- berries of fine heavy sorts, will be preserved from getting dirty and rotten by tying their stems to little sticks; by this prac- tice, the fruit also gets better ripened, and of a finer flavour. Some persons lay tiles or moss round the plants when the fruit is half-grown; but this is not, generally, so well, only it has the advantage in keeping the ground cooler in a hot season. The first and finest scarlets best deserve this trouble. Flowers should be frequently tied up, and dead and dangling parts trimmed off. Some of them cannot do without support, and many sorts are made more secure and beautiful by proper ties. The Sticks used for flowers should be of smooth wood, as meat painted slips of deal, with or without an ornamental head; white is the best colour, on account of its contrast with the leaves. Decaying flowers should be timely trimmed or removed, and perennials should be regularly freed from the parts running to seed, (except so much as may be wanted,) as the production of seeds weakens the roots much. Of Propagations.-Plants are propagated by seeds, suckers, slips, off-sets, divisions, cuttings, layers, and grafts. By seed, is the most general method of propagation, and plants raised any other way are seldom so fine. Those plants from seed which have never been removed, are commonly handsomer, and some forwarder, than those that have been transplanted, pro- vided they are sown in a proper soil and situation. Com- monly speaking, new seed is to be preferred to old, as growing the ºore luxuriantly, and coming up the surer and quicker. If old seed is knowingly sown, some allowance, in point of time, must be made. Pease and beans of two years old are, by some, preferred to new, as not running so much to straw. As to the age of seeds at which they may be sown and germinate, it is uncertain, and depends very much how they are preserved. Seeds should be saved from fine forward plants, secured from rocking about when they getºtall; guard them against birds, gather them regularly as they ripen, lest they are shed and lost, and keep them dry. . Curious flower seeds are kept well in phials; others may be put into small drawers, and some hung up, or laid on shelvés, in their pods. Seeds may be forwarded for sowing by various ways of promoting a germina- tion before they are put into the ground. Broad and kidney beans may be put into soft water about 24 hours, to forward their growth, and to ascertain their vitality. The smaller seeds, as carrots, &c. may be prepared for sowing, by simply mixing them in a little moist sand, or fine earth, taking care that they do not lie longer than the usual time of their beginning to sprout. The season for committing seeds to the ground should be as early as the nature of the plant to be cultivated will bear. Let this direction for early sowing be understood, not only of spring, but autumn crops; that the plants designed for winter use, or to stand for spring, may be strong, and well established in the ground, though for those designed for spring, it is advisable to have two or three different sowings. To be sure of a crop, and in some things a succession of crops, various sowings should be made through the year at ali times, that are not too unnatural as to season; for it is an object in gardening, not only to have early and late produc- tions, but never to be without what may be produced. Sow- ings should be generally performed on fresh dug or stirred ground. The digging should, therefore, be done as near the time designed to sow as can be. If the ground turns up raw or wet, as early in the spring it is apt to do, a little time must be allowed it to dry, and so also if rain falls first. In this case, seed should be sown as soon as ever the ground may be trampled on without hanging to the feet. The proper depth at which seeds should be sown, is to be carefully observed; if too deep, they will either rot or not thrive well; and if too shallow, they are liable to be injuriously affected by frost, wind, drought, or birds; but of the two, rather too shallow than too deep is the best. The smaller the seed the finer should the soil be, and the less also the covering; so that while some, as the seed of celery, is to be but barely covered; others, as pease and beans, may have a depth of two, three, or four inches. But some regard is to be had to the season and soil; in a warm season, and light soil, sow deeper, and the contrary in shallower. The quantity of seed sown is a thing to be attended to with some exactness. Small seeds go a great way, and require a careful hand to distribute them; for though sowing a little too much is a trifle as to the value of seeds, yet to have them come up crowded thick is an evil. - It is not generally advisable to sow several sorts of seed on the same spot, as some persons are accustomed to do. Somc little things of this sort indeed may be done, as a piece of ground newly planted with horse-radish, may be top-cropped with radishes or spinach, &c. A thin crop of onions upon new asparagus beds, may also take place, drawing them while young from about the plants. All seeds come up best when moderately pressed with the earth; for if they lie too lightly in contact with it, cold and drought more easily affect them; and when once seeds begin to germinate, they are impatient of both. To trample seeds is, on the whole, better than any other pressure. This done, lay all immediately and neatly level with a wide rake, drawing off stones, &c. but do it lightly, to avoid driving in the teeth of the rake, which would remove the seed, and make it come up irregularly. Propagation by suckers, is a mode of culture peculiar to trees and shrubs. The things to be observed in this business are, to take them up with some care from the mother plant, so as not to injure its root, nor the sucker's own root, by pulling it up without properly loosening it first. The earth should ‘be moved aside with a trowel, and then the sucker cut off with a knife. Wherever a root appears barked, the part below should be cut off. If it is desired to succeed well, in propa- gating by suckers, consider that all young roots are tender; let them be trimmed to form, and planted immediately. Suck- G A. R. G. A. S 359 DictionARY of MECHANICAL scIENCE. ers with poor roots must have their heads reduced the more. Propagation by slips, is of two sorts, either from the root or stem ; and several sorts of flowers and herbs are increased this way. When from the roots, if the whole is not taken up, move the earth carefülly aside, and slip off by a pressure of the thumb and finger, and be &autious of hurting the fibres of the slips, planting with good mould about them. Take off slips from the stem carefully by the push of the thumb, and not too many from the same plant, as it is apt to injure the place by tearing off some of the wood. - Offset, is a term sometimes applied to slips from fibrous roots; but more properly so from bulbous roots, which put forth many offsets. These are slipped away at the time they are taken up for removal or replanting, and commonly take two or three years before they bear flowers; dispose of them, therefore, in a nursery, where they may remain undisturbed till they come to a flowering state. Division of the roots, is a way of propa- gating many sorts of plants. To this end, of course they must be taken up, and then either carefully pulled, or cut asunder with a sharp instrument, as the case may require. . It is not safe, however, to divide such roots into very small pieces. The general season for thus splitting fibrous-rooted plants is Octo- ber, but it may be done early in the spring, as February. Cuttings, of a variety of woody plants, will grow, and many trees and shrubs are propagated this way; but their sap must be of a watery nature, as those plants that are gummy will not strike, (or rarely,) though ever so much care is bestowed or time allowed them. The texture of the wood cuttings must be somewhat soft, as hard-wooded ones will not grow. The sea- son for setting slips and cuttings is for some plants summer, as wall-flowers and myrtles; and for most, from October to March; but in general, the sooner the better. It has, how- ever, been said, that spring is the best time for all, and that the sap should be in motion first. Cuttings should be well- ripened wood, and have the earth pressed to them the whole length they are in the ground, i. e. from four to six inches. Cut them with a sharp knife slopewise, and plant in a good soil, so situated as to have only the morning sun, and keep them cold (not wet) by occasional watering in dry weather. Laying of branches, is a mode of propagation that may be adopted for almost all forest trees, and several sorts of fruit trees and shrubs, i.e. all that will grow from cuttings, and many that will not. Layers are made of the lower branches of the plant, which must be young and pliable, to bend down without breaking, to the depth of four, five, or six inches, in the ground, as the soil is light or heavy, at which they must be held securely by good pegs. Let the ground about layers be kept cooi by occasional waterings, and laying some moss, turf, litter, or rather small pebbles, about them, which will not har- bour insects. The part out of the ground may be supported erectly by a tie to a stick. It is a good way to slit with a sharp knife the part at the peg, as in carnation layers, a little more than an inch; and some prick a few holes about the part, at a joint, with a blunt awl, to help the layer to strike root. Gene- rally, layers should be shortened to six or eight inches above the ground, or do it to two eyes, be it more or less above ground. Where there are no branches low enough to be brought into the ground, and it is not thought good to head down for the production of low shoots or suckers, plants may be layered by fixing a broken pot or a box, with a slit in the side, to the height necessary to lay in a branch. A branch also, if long enough, may be thrust through a hole of a garden pot upwards, then filled with earth, and supported by some contrivance, and shaded by some means, and in both cases water frequently the buds drawn through the hole of the pot. By this contrivance, rooted plants being procured in pots, may be turned out with the earth about their roots undisturbed. A branch of a vine thus layered in. November, may be next year cut off, when the fruit is ripe, brought in a pot to table, and afterwards planted out. For propagation of fruit trees by grafting, see that article. —Watkin's Cyclopædia. - GARLAND, a sort of net, whose opening is extended by a wooden hoop, of sufficient size to admit a bowl or platter within it; it is accordingly used by sailors as a locker or cupboard, to contain their provisions, being hung up to the beams within the birth, where they commonly mess between decks. Shot GARLAND, a piece of timber nailed horizontally along the ship's side from one gun-port to another, and fitted with several hemispherical cavities, to contain the round-shot ready for charging the great guns in battle. - - à GARLIC, the root of the Allium. This root has been sub- jected to chemical analysis; and is found to consist of albumen, mucilage, fibrous matter, and water. GARNET, a sort of tackle fixed to the main-stay of a mer- chant ship, and used to hoist the cargo in and out at the time of lading and delivering her. GARNET, in Mineralogy, is a species of the flint genus, of which there are two sub-species, viz. the precious, and common. The precious, or oriental, is red, but of various shades. It occurs most commonly crystallized, either as a dodecadron, or as a double eight-sided pyramid. Garnets are found in almost every country where primitive rocks exist. Switzerland and Bohemia are the two countries in Europe which furnish them in the greatest abundance. The impure garnets are used to advantage as a flux when they are found near the iron-mines, as they not only facilitate the fusion of that metal, but add Something to the mass by contributing a portion of iron. GARNISH, in Law books, signifies to warn. GARNISHEE, used for the third person or party in whose hands money is attached within the liberties of the city of Lon- don, so called because he has had garnishment or warning not to pay the money, but to appear and answer to the plaintiff's creditor's suit. - GARNISHMENT, is a warning given to a person for his appearance, for the better furnishing of the cause and court. GARRISON, in the art of war, a body of forces disposed in a fortress, to defend it against the enemy, or to keep the inhabitants in subjection; in the latter case, the garrison should always be stronger than the townsmen. Garrison, or winter quarters, signify a place where a number of forces are laid up in the winter season, without keeping the regular guard. GARRiso N. Guns, such as are mounted and used in a garrison, consisting of the following weights, viz. the 42, 34, 24, 18, 12, 9, and 6 pounders, being made either of brass or iron. GARTER, ORDER of THE, a military order of knighthood, instituted by King Edward III. It consists of 26 knights com. panions, generally princes and peers, whereof the king of England is the sovereign or chief. The college of the order is in the castle of Windsor, with the chapel of St. George, and the Chapter-house, erected by the founder for that purpose. The habit and ensign of the order are a garter, mantle, cap, george, and collar. The garter, mantle, and cap, were assigned the knights companions by the founder, and the george and collar by Henry VIII. The garter is worn on the left leg between the knee and calf, and is enamelled with this motto, hon soit qui mal y pense, i.e. “shame to him that evil thinks hereof.” GAS, in Chemistry, a word that signifies a permanent elastic aériform fluid. , Gases are transparent, elastic, weighty, and in most cases invisible ; they cannot be condensed into a solid state by any degree of cold hitherto known. The air or atmosphere consists of a mixture of several gases, which may be obtained separately. The gases which we shall describe are, 1. Atmospheric Air. 9. Sulphuretted Hydrogen Gas. 2. Oxygen Gas. 10. Phosphuretted Hydrogen 3. Nitrogen Gas. - Gas. 4. Hydrogen Gas. 11, Nitrous Gas. 5. Carbonic Acid Gas. 12. Nitrous Oxide Gas. 6. Light Carbonated Hydro- 13. Ammoniacal Gas. gen Gas. 14. Sulphurous Acid Gas. 7. Heavy Carbonated Hydro- 15. Hydrochloric Gas. gen Gas. | 16. Chlorine Gas. 8. Gaseous Oxide of Carbon. 17. Fluoric Acid Gas. Atmospherie Air.—The mechanical properties of atmospheric air, such as its weight, elasticity, &c. are considered under the articles AIR PUMP and PNEU MATIcs. Chemistry examines all its other properties. The air of our atmosphere consists of two elastic, ačriform bodies, called oxygen and nitrogen gases, possessing different properties; oxygen gas is capable of supporting combustion and animal life; nitrogen, gas is destructive to animals, and extinguishes fire. The atmosphere contains carbonic acid; for alkalies become effervescent where 360 G. A. S G. A. S DICTIONARY OF MECHANICAL SCIENCE. exposed to it, and lime-water acquires a pellicle, or thin skin on its surface, on being exposed a sufficient time to the action of the air, even upon the highest mountains. Water also in the state of vapour is always found in the atmosphere. . . . Oxygen Gas, is an elastic invisible fluid, having neither taste nor smell, nor shewing any signs of acidity; it is 740 times lighter than the same bulk of water... Its weight is to that of atmospheric air as 1103 to 1000. It is absorbed only by com- bustible bodies. It is necessary for respiration, and produces animal heat. It is considered the cause of acidity, and from this property is named oxygen, derived from two Greek words, denoting the cause of the acidity; these are ośvc, acid, and ywopat, to produce or generate. Oxygen gas is procured in great purity from pure oxygenated muriate of potash. We have before described the method of obtaining this and other gases. It may likewise be obtained from the green leaves of plants, but not in sufficient quantity for chemical experiments. Nitrogen or Azotic Gas, will not support life by respiration, but quickly kills animals that breathe it; plants, however, thrivé, and even flourish in it. It has no taste. It neither reddens blue vegetable colours, nor precipitates lime-water. No combustible substance burns in nitrogen gas. . It cannot be absorbed by water. It unites to hydrogen, under certain circumstances, and with it constitutes ammonia. When united to oxygen in different proportions, it forms atmospheric air, gaseous oxide of azote or nitrogen, nitrous gas, nitrous acid, and nitric acid. It is a component part of all animal sub- stances; from which it may be obtained. - Hydrogen Gas, or inflammable air, is found in a natural state in muddy waters and in marshes, in mines, in coalpits, and in the bowels of animals. In these states, however, it is generally combined with carbon, sulphur, and phosphorus. It is exhaled from all places where there are animal or vegetable matters in a state of putrefaction. Hydrogen gas is obtained in a state of purity by decomposing water, because its base is one of the constituent parts of that fluid. This gas, therefore, has been called hydrogen, from two Greek words vôop water, and yuuouau, to generate, that is, the generator of water. Carbonic Acid Gas, (the first elastic aeriform fluid, different from common air, that was known,) cannot support flame, nor animal life; its taste is acid, and its specific weight is to that of atmospheric air, as 1:500 is to 1000. It may be poured from one vessel into another. This may be shewn by placing a lighted taper at the bottom of a vessel, and pouring carbonic acid gas over it from another vessel. The light will be imme- diately extinguished. Hence we infer, that the gravity of the gas has enabled it to descend, and to displace the common air at the bottom; which being lighter, is of course obliged to ascend. Carbonicaeid gas is diffused in the greatest abundance throughout nature. * Marble, limestone, and chalk, consist of this acid and lime. Carbonated water, or, as it has been called, soda water, is merely water impregnated by carbonic acid. This agreeable draught is made in a series of vessels containing water and common chalk. Sulphuric acid is poured in, which unites with the lime, and at the same time the carbonic acid is expelled. This acid is absorbed by the water which is ready to receive it. The sparkling of carbonated waters is owing to the rapid escape of the gas. What is called soda water, or, more pro- perly speaking, carbonated water, is made in H' * an apparatus, of which the annexed is a figure. C is a flat vessel, having a cock D, through which chalk and sulphuric acid are supplied for forming the gas, which passes through the tube H, by a valve into the ves- sel B, containing the water to be saturated, and which may be drawn off by the cock E. Into this vessel is inserted a tube proceeding from another vessel A, also charged with . water, and having an opening F, in which is placed a stopper, and through which fresh water is occasionally poured. The water in the upper vessel, and the weight of the stop- per, press and agitate that in the vessel B, by which it is more speedily impregnated. The - whole is made of glass, and is termed Nooth's apparatus. . For the general purposes of impregnating water with gases, a set of glass vessels (called Woulfe's apparatus) is used. Annexed is an engraving of this apparatus. A is a retort hav- ing a tubulure, through which the materials for procuring any gas are passed. B is a globe * receiver, into which is | # § º - §§§ inserted a tube C, bent at right angles, and communicating with the second receiver D. From this one, another tube proceeds in the same way to the third receiver, and from the third another passes to the fourth. E is the last tube, which passes through water into any vessel, for the reception of the most volatile product, or that which will not combine with the water or other fluid contained in the three-necked bottles. It will be seen that a perpendicular tube enters the middle neck of each receiver. These are safety tubes to prevent the apparatus from bursting, as the gas might be evolved too quickly from the retort to be absorbed by the water. Sometimes these tubes are bent at right angles, and have a drop of mercury in them, which moving up and down, according as the gas is abundantly generated, acts as a valve, permitting the superabundant gas to escape. By means of this apparatus, water may be impreg- nated by muriatic acid and nitrous gases, so as to form muriatic and nitric acids. To shew that carbonic acid gas is fatal to animal life, put a mouse, or other small animal, into a vessel filled with it, and cover the vessel to prevent the admis- sion of atmospheric air. The animal will die in a minute or two. It is this gas which has produced so many fatal accidents at the opening of cellars or vaults, in which wine, cider, or beer, has been fermenting. - Light Carbonated Hydrogen Gas, is hydrogen gas holding charcoal in solution. There are several kinds of it obtained by different processes, which differ in their properties, and in the proportions of their constituent principles. This gas is obtained from animal, vegetable, and mineral substances. Nature produces it in marshes and ditches, on the surface of putrid water, in coal mines, burying places, common sewers, and in those situations where putrid animal and vegetable matters are accumulated. It is also generated in the intestinal canal of living animals, and may be plentifully obtained froln most stagnant waters. It may also be obtained during the distillation of animal and vegetable matters. This gas is known in coal mines by the name of fire-damp. Its destructive effects had probably been felt in all collieries until this moment, but for that useful invention of the immortal Davy—the safety lamp ; or, as the miners in gratitude term it, “the Davy.” This lamp is on the principle of the impossibility of the passage of inflamed gas through apertures of small diameters. Accord- ingly, wire-gauze is used for this purpose. See LAMP. Heavy Carbonated Hydrogen Gas, was first noticed by some Dutch chemists, who observed in it a particular property, that when it was combined with oxygenated muriatic acid gas, the aériform state of both fluids was destroyed, and oil was pro- duced; for which reason they call it olefiant gas. This gas is obtained in decomposing spirits of wine by sulphuric acid in a great heat. It is also obtained abundantly, when alcohol is passed through a red-hot earthen tube. Sulphuric ether, mixed with sulphuric acid, and subjected to heat, also affords it. Gaseous Oaside of Carbon, first described by Dr. Priestley, is exceedingly noxious; animals die initinstantly. It is obtained from chalk and filings of zinc. a. * * - Before closing these articles we may observe, that carbonic acid gas—the choke damp of mines—escapes also during the fermentation of porter; and instances of its destructive effects have occurred, where persons have incautiously put their noses to the bung-holes of casks while this process was going on. Charcoal fumes, so deleterious in many manufactories, are generated by burning charcoal in common air, and are in fact G. A. S. G. A. S. DICTIONARY OF MECHANICAL SCIENCE. 361 nothing more than carbonic acid gas fumes. A pan of lime- water placed on the floor will absorb the gas, and allow the artizan to respire tolerably pure atmospheric air. Yet, strange as it may appear, carbonic acid gas is evolved from our lungs in respiration, as is proved by breathing into a phial containing pure lime-water, which will become quite turbid by the com- bination of the pure lime with the carbonic acid proceeding from the lungs. Sulphuretted Hydrogen Gas, has the properties of an acid; for when absorbed by water, its solution reddens vegetable blues. It combines also with alkalies, earths, and with several This gas has an odour resembling that of metallic oxides. putrid eggs. It kills animals, and extinguishes burning bodies. It is inflammable when mixed with oxygen gas, or atmospheric alſ. of Harrowgate, Aix-la-Chapelle, and St. Bernard’s Well at Edinburgh. Phosphuretted Hydrogen Gas, consists of phosphorus dissolved in hydrogen gas. It is the most combustible substance in mature, and is distinguished from all other gases by taking fire when brought in contact with atmospheric air. When mixed with oxygen gas, or with oxygenated muriatic acid gas, it burns violently. When bubbles of it are suffered to pass through water, they take fire in succession as they reach the surface of the fluid. Its smell resembles that of putrid fish. Thosphoretted hydrogen gas is also found naturally. The air which burns at the surface of certain springs, forming what are called burning. springs, and the ignis fatuus (jack o'lantern,) which glides along burying grounds, consists of this gas. Nitrous Gas, is an aeriform fluid, consisting of a certain quantity of nitrogen gas and oxygen. It is colourless, having no sensible taste, and is neither acid nor alkaline; it cannot be respired. The greater number of combustible bodies can- not burn in it. It is, nevertheless, capable of supporting the combustion of some bodies. Phosphorus burns in it when introduced in a state of inflammation. Homberg's pyrophorus takes fire in it spontaneously. It is obtained from copper and nitric acid diluted with water. Gaseous Oaside of Azote, or nitrous oxide, obtained from the nitrate of ammonia, by heating the salt to about 400°Fahren- heit, is a permanent gas, in which animals, when confined, give no signs of uneasiness at first, but soon become restless, and then die. When mingled with atmospheric air, and then received into the lungs, it generates highly pleasurable sensa- tions. It excites the body to action, and rouses the faculties of the mind, inducing a state of great exhilaration, and an irre- sistible propensity to laughter, a rapid flow of vivid ideas, and unusual vigour and fitness for muscular exertions; in some respects resembling the sensations attendant on intoxication, without any languor, depression of spirits, or disagreeable feelings afterwards, but more generally followed by vigour, and a disposition to exertion, which gradually subsides. Ammoniacal Gas, is composed of hydrogen and nitrogen, ren- dered gaseous by the addition of caloric. This gas suffocates animals, and extinguishes burning bodies, like all the other suffocating gases; but it is slightly inflammable, increasing the flame of a taper before it extinguishes it. Sulphurous Acid Gas, is no where found in a natural state, but is entirely a production of art, obtained by exposing to heat in a retort, sulphuric acid, while it is exercising an action on some combustible body, as oil, charcoal, mercury, &c. Sulphurous acid gas is twice as heavy as atmospheric air. It extinguishes burning bodies, and suffocates animals. It first reddens, and then destroys, most of the vegetable colours. It has the pro- perty of whitening silk, and giving it a lustre. - Hydrochloric or Muriatic Acid Gas, obtained by exposing to heat, fuming muriatic or hydrochloric acid, put into a retort, the beak of which is introduced below a bell-glass filled with mercury, and placed on the shelf of a mercurial pneumatic apparatus, is heavier than atmospheric air, Suffocates animals, and extinguishes a lighted taper; but first enlarges its flame, and makes it appear of a green or bluish colour at the edges. Chlorine or Oaygenated Muriatic Acid Gas, the muriatic gas deprived of its hydrogen, is of a greenish yellow colour. This gas destroys vegetable colours only, rendering all flowers, and the green leaves of plants, white; and alkali is not capable of It is this gas which gives their peculiar smell to the waters restoring their colours. Hence this acid is now very generally employed in the gaseous or the liquid state, to whiten thread, cotton, linen, wax, &c. • * - - . The oxygenated muriatic acid is employed in four different ways for the purpose of bleaching; first, in the state of gas alone; secondly, in the state of gas combined with water, or what is called the acid; thirdly, potass is mixed with the acid to condense the gaseous vapour, and destroy its suffocating odour; fourthly, oxygenated muriates, dissolved in water, are employed. See the article BLEACHING, pp. 108–111. . . Fluoric Acid Gas, may be obtained by decomposing fluate of lime (Derbyshire spar) by means of sulphuric acid. The most remarkable property of this gas is its power of dissolving silex; it therefore dissolves glass, crystal, and various precious stones. It is heavier than common air. It does not maintain combustion, nor can animals breathe it; but its property in dis- solving flint makes it useful in etching on glass, either as a gas, or in a liquid state. - There are a variety of other gases, the enumeration of which in this place would be attended with little utility to the reader of a work like our Dictionary. - • On the Expansion of Gases ; with an easy Rule, and a Table, for finding the Eapansion of Air or any Gas, from 32° to 212° Fah- venheit.—An accurate knowledge of the expansion of gaseous bodies being of great importance in chemical researches, many experiments were made to ascertain it, but the results were long so various and different from each other, that none could be depended on... The reason of this difference was the want of attention on the part of experimenters, in not excluding with sufficient care the particles of water from the vessels employed to measure the expansion of gases. When, therefore, heat was applied to raise the temperature of any gas, the particles of water were converted into vapour, and mixing with the gas, produced a difference in the actual change of bulk which it had experienced. To this cause only can be ascribed the varia- tions in the determinations of Deluc, General Roy, and others, on this important point. The subject happened to engage the attention of Dalton, of Manchester, and Gay Lussac, in France; and the coincidence in the results of their experiments affords convincing proof of their accuracy. Dalton published the account of his experiments about six months before Lussac, and his apparatus was more simple than that of the French chemist. It consisted merely of a glass tube, open at one end, and graduated into equal parts; after it was properly dried, the gas was introduced into it, and it was then filled with mercury at the open end to a given point; heat being then applied, the amount of dilatation was observed, by the quantity of mercury expelled. Lussac's apparatus was more complicated, but capable of greater precision; and, as his experiments were made in greater quantities of air, their coincidence with the former induced perfect confidence in the accuracy of the results. Their experiments led to the important conclusion, that air, and all gaseous bodies, undergo the same degree of expansion, by the application of the same degree of heat; so that the rate of expansion for one being determined, gives the rate of expan- sion for all. The expansion obtained by Gay-Lussac, by heat- ing air from 32° to 212°, was 375, or § of its bulk at 32°, and that obtained by Dalton, was 376 for the same bulk. Now, this fact being established, that air. expands about 3, or one- 2,666th of its bulk, when heated from 32° to 2129, or 1809; it follows, that for every 19 of the thermometer, air will expand one-four hundred and eightieth part of its bulk at 32°. The experiments of Dalton would give about one-479-8th for this expansion, but the difference is of no great moment. From the experiments of Lussac, it appears, that the steam of water, and the vapour of ether, experience the same expansion as air, when the same addition is made to their temperature; hence it may be inferred, that all elastic fluids expand equally and uniformly by heat. - - To determine, therefore, the expansion of air, or any gas, at any temperature, or in other words, to ascertain the increase of bulk which it undergoes, when heated from the commencement of the common thermic unit 32°, to any degree within its range, which terminates at 212°, we have only to add one-480th part of its bulk, at 32° for every degree between that point and the temperature required. 4 Z 362. G. A. S G. A. S DICTIONARY of MECHANICAL SCIENCE, Thus, if the bulk of a quantity of any gas at 32°, be 10 cubic inches, and its bulk at 60° be required, we have only to sub- tract 32° from 60°, and the remainder 28 is the number of * tº te 1 *- 28 * e degrees intervening; then: 480 * 28 = 480 the expansion of a 28 - t 280 = 1 A f O . % . ... * • — Nº e - º – — — - - A tº unit for 28°; wherefore, 450 * 10 cubic inches – 480T 5833, the increase of volume, which, added to 10 cubic inches, makes 10:5833 cubic inches, the bulk of the gas at 32°, when raised to the temperature of 60°. If the bulk of a quantity of gas, at any temperature above 32° be given, and its bulk at a still higher temperature be required, we must first subtract 32° from the given temperature; then add the remainder to the denominator T - - of the fraction 7; and proceed as before. Thus, to find the 480 - expansion of 10 cubic inches of gas at 50°, when raised to the temperature of 60°, we have 50° — 32° = 18°, and 60° — 50° T 10 × 10°– : tºº-º-º: * o sº -- * gººmsº grºss - * * - * - 10 • * * expansion of a unit for 10°, wherefore 498 ° 10 cubic inches - 100 * 498 cubic inches, the bulk of the gas at 50°, when raised to the temperature of 63°. If the bulk of a quantity of gas at a higher temperature begiven, and its bulk at a lower temperature be required, we must then subtract 32° from each temperature, and add the remainders to the denominator of the fraction ºn ; then making the least sum the numerator, and the greatest the denominator of a new frac- tion, we proceed with the operation as before. Thus, to find the contraction of 10 cubic inches of gas at 80°, when cooled to the temperature of 60°, we have 60°– 32° = 28°; and 80°–30°- • a 5. * . r - 480 + 28 508, «". e - - O wº- ºr O gº O * == <= <= sº-sº ºme sº- = 208, the increase of volume, which, added to 10 the ex- * e •. 508 tº º pansion of a unit for 20°; wherefore, B23 * 10 cubic inches = +...+ = 9.4318 cubic inches, the volume of the gas at 80°, when cooled down to the temperature of 60°. Such is the mode of calculation adopted by chemists, in the calculation of the expansion of air and gas, and the examples ‘might be so varied as to give occasion for a variation in the, rules for each ; but we proceed to give a much more simple and general rule for determining this expansion in every case that can be proposed within the thermic unit. Rule.—The volumes of all the gases are to each other as 448 -- the temperature; that is, as 448 + the given temperature, is to 448 + the required temperature, so is the bulk of a quantity of gas at the given temperature, to its bulk at the required temperature. Thus, in the first of the above cases, we shall have 448 + 32°: 448 + 60° : : 10 cubic inches : 10:5833 cubic inches, or 480 : 508 : : 10 cubic inches : 10:5833 cubic inches, the bulk of the #. at 32°, when raised to the temperature of 60°. as found 3DOVC. - In the second case, we shall have 448 + 50° : 448 + 60° :: 10 cubic, inches : 10-2008, cubic inches, or 498 : 508 :: 10 cubic inches : 10-2008 cubic inches, the bulk of the gas at 50°, when raised to the temperature of 60°, as found above. . In the third case, we shall have 448 + 800 : 448 + 600 : : 10 cubic inches : 9:4318 cubic inches, or 528 : 508 : : 10 cubic inches : 9,4318 cubic inches, the bulk of the gas at 80° when coolcd down to the temperature of 60°. From these examples will be seen the superiority of this single rule, to the former methods of calculating the increase or diminution of the volumes of gases, when expanded by heat, or contracted by cold. * t ... The following Table, constructed on these principles, shews the expansion of air for nearly every temperature, from 32° to 212°, supposing that its bulk at 32° is unity 1-000000, or 1000000. Tāfile. Temp. Bulk. itemp. 13tulk Temp. Bulk. - - * ——- —a-- * - - - - * Wº 320 1000000 590 1056249 869|| || 112499 33 1002083 60 1058333 87 | 11 14583 34 1004166 61 1060416 88 || 11 16666 35 1006349 62 1062499 89 1118749 36 || 1008333 63 1064583 90 | 1120833 37 1010416 64 1066666 91 | 122916 38 101.2499 65 1068749 92 11.24999 39 1014583 66 10708.33 93 J 127083 40 1016666 67 1072916 94 || 1129166 41 10 18749 68 1074999 95 1131249 42 1020833 69 1077083 || 96 || 1 133333 43 1022916 70 1079166 97 11354 16 44 || 1024759 71 1081249 98 || 1137499 45 || 1027083 72 1083.333 99 || 1 1395.83 46 1029166 73 10854 | 6 100 1141666 47 1031249 74 1087499 | | 0 || 1 || 62.499 48 1033333 75 1089333 || 120 1183.333 49 1035416 76 | | || 09 1666 130 | 1204166. 50 1037499 || 77 10937.49 140 | 1224999 51 10395.83 78 || 109;833 150 | 1245833 52 1041666 79 1097936 160 | 1266666 53 I 0437.49 80 109.9999 170 1287.499 54 1045833 81 || 1 || 02083 } 80 | 1308333 55 10479 16 $2 : 1 104166 190 1329166 56 || 104.9999 83 1 106249 |200 | 1349.999 57 1052083 | 84 1108.333 || 2 || 0 || 1378823 58 1054166 85 || 1110416 |2|12 || 1375,000 Table shewing the Absolute Hºeights and Specific Gravity of Gases, and the Quantity of each absorbed by Water.--Tempe- rature 60° Fahrenheit. Barometer 29°8. $ Specific Gravity. Weight of KIND OF GAs. |109 cubic Water the Air the | inches, standard standard. |in grains. at 1000. Nitric acid,. . . . . . . . . . . . . ... . . . 76' | 3: 2425 Sulphurous, . . . . . tº g g tº e º C & . . . . . 70°215 2.75 2240 Vapour of ether, . . . . . . tº ſº e º 'º tº e '62°1 s ſº tº o 2250 Muriatic acid, . . . . . . . . . . . . . . . . 59'8 gº dº gº tº 1929 Vapour of alcohol, ... . . . . . . . . 51°5 tº e º º 2100 Nitrous oxyde, . . . . . . . . . . . . . . 50°1 1°985 1615 Carbonic acid, ... . . . . . . . . . . . . | 46.5 1°84 1500 Ditto, ditto, . . . . . . . . . . . . . . ... I 45'5 1-802 || 1470 Muriatic acid, ...... . . . . . . . . . . 44"7 I '765 1430 Sulphuretted hydrogen, ...... 48° 17 º ºg º ºs 1231 Nitric oxyde,. . . . . . . . . * g e º ºs º º 37- 1°465 | 193 Nitric oxyde, . . . . . . . . . . . . . ... 34’3 | 1.36 T105 Oxygen gas, . . . . . . . . . . . . . . . . . 34.74 1°39 1127 Sulphuretted hydrogen, ...... 34,286 1-36 1142 Oxygen gas, . . . . . . . . . . . . . . . . 34° 1°35 11()3 Atmospheric air, . . . . . . . . . . . . 31° 1-2279 || 1000 Azotic gas,. . . . . . . . . . e e e Q & a tº e 30.535 | 1:21 985 Azotic gas, . . . . . . . . . . . . . . ... i 30°45 T-20 980 |Carbonic oxyde, ... . . . . . . . . . . 30° 1-185 967 l'Olefiant gas, . . . . . . . . . . . . . . . . . 28°18 ſº tº & O 905 |Hydrocarburet from stagnant f * water, . . . . . . . . . . . . . . . . . . . . 20.66 tº C º (e 666. Ditto from coal, . . . . . . . . . . . . . . 20°2 tº e º º 650 - Ditto from ether, ... . . . . . . . . . . . 20° tº º ſº º 645 Ammonia, . . . . . . . . . . . . . . . . . . 18-16 || 0715 : 585 Ditto, . . . . . . . . . . . . . . . . . . . . . . 18' 0-713 580 |Arsenicated hydrogen gas, ... . . . . . 0-6499 || 529 | Hydrocarburet from alcohol, ... 16" . . . . . 516 Ditto, from water over ignited - !. charcoal,... . . . . . . . . . . . . . . . . . 145 tº e º º 468 || | Hydrogen gas, ..............] 2.613 || 0-1031 ‘84 Phosphuretted hydrogén, ... . . . . . . . . tº e º 'º . . . . . . G A. S. G. A. S DICTIONARY OF MECHANICAT, SCIENCE, Gas Light. In the article CoAL we described the method of obtaining this artificial light. Our object in the present instance is, to describe and illustrate the apparatus of a manu- factory of Gas for public use. We shall, therefore, avail our- selves of Mr. Peckston's work on Gas Lighting. It is the work of a practical man, and in that respect equal to the late Mr. Creighton's treatise on Gas, in the supplement to the Encyclo- paedia Britannica. e Gas is obtained from distilling coal in a RETORT-it is then PURIFIED–and, finally, let off to the consumers by means of pipes. The consideration of the two processes of distillation and purification solicit our chief attention; the process of dis- tribution shall be briefly discussed, when the former steps shall have been fully explained. been invented rotatory retorts. I am to be understood as speaking of that section which is vertical and parallel to the flanches at their mouths) are cylin- ders of about six feet in length, and twelve inches diameter inside. These have, till recently, been set on the flue plan, and when set two to one fire, carbonization was carried on at about twenty per cent. ; or, to speak in more familiar language, it required twenty chaldrons of coals to keep a sufficient number of retorts so heated as to be capable of carbonizing one hun- dred chaldrons in a proper manner; when the retorts were worked at eight hours’ charges, with two bushels of coals to one retort each charge. The fire-place for heating this kind of retort was opposite to its mouth; and under these circum- stances, a retort, cast from metal of the second running, and weighing about ten hundred weight, would last from eight to ten months. - The first step towards the present mode of setting retorts was, by heating three with one fire; on such plan several were set in different works. Retorts set three to one fire having, by experiment on a large scale, been proved to answer no desir- able end, the next alteration in the mode of setting was, that of heating four by one fire. On this plan, a hundred retorts were put up at one of the establishments in London—these it was found impossible to heat; for one part of the retort would have actually melted before the other had arisen even to a dull red. A second setting of retorts, in which four were to be heated by one fire, succeeded better than the first, for the retorts heated very regularly—but carbonization was not carried on at so low a per centage as when only two were heated by one fire; it was considerably increased, and what was still worse, the retorts were sooner burnt out. its expenses, till at last it rose as high as fifty per cent. This was owing principally to working fewer retorts than the fires necessary to be kept up would have heated, had the retorts placed over each fire in action remained in a workiug state; for it very frequently happened, when seventy or eighty retorts were working, as many fires were kept lighted as actually heated a hundred, and for the following reason:—The action of the fire not being uniformly directed towards each retort in the series of four, one of them became ineffective ; when such was the case, only three out of the four could, of course, be used ; soon afterwards a second failed, and then but two , remained in use, and so on ;-indeed, it was no uncommon circumstance to work but two retorts by that fire which actually heated four, owing to two of them being burnt out. When retorts were set four to one fire, it happened that they were frequently worked under the above disadvantage more from necessity than choice; for whenever it became necessary to remove defective ones over one fire, it followed that the adjoin- ing fires could not be kept lighted; for if they remained so, the bricklayers could not perform their work—consequently, when it was required to replace a series of four, the use of twelve retorts was lost to the manufacturer till such time as the defective ones over the fire-place undergoing repair, were again ready to be brought into action. The pulling down of the defective retorts, and the replacing of them so as to be again ready for charging, in one series, was seldom accomplished in less than a week; therefore, when the manufacturer was The carbonization increased daily in infany weeks. - this plan answer, that it has been tried almost under every bearing; and whilst some attempts have promised to answer, unable, from the quantity of gas he had to supply, to dispense with the use of so many retorts, he was compelled to work them under every disadvantage. - As the expense of resetting one retort, when put up in a series of four, for labour and new materials, exclusive of the retort itself, amounted to about eight pounds, or at the rate of thirty-two pounds for each series, it became a desideratum to be able to replace a burnt-out retort without pulling down the brickwork and allowing the retorts next adjoining to remain inactive. Actuated by a zeal for promoting the interest of the manufacturer, my attention was turned to the subject; and, after very maturely considering the matter, Mr. Peckston hit upon a plan which would enable the operator to remove a - - | defective retort in a few hours, without expense, save labour, The retorts used for the distillation of pit-coal, are of differ- ent shapes in different establishments, being in some circular, in others elliptical, square, or semicircular. There have also | ones were guarded by tiles from the action of the fire in the The circular retorts (for, in adverting to the shape of them, and a few shillings for bolts and cement, When retorts were set four to one fire, the top ones invari- ably failed first, and this led to a supposition that if the top same way that the lower retorts were guarded, they would be more likely to remain a longer time effective. Retorts were accordingly so set, and whilst the fire-places were continued at that side which was opposite to the side for charging and drawing, they did last considerably longer, but then they were by no means so effective as on the former plan. They fell out of all shape, and consequently were not capable of carbonizing such a quantity of coals as would be advantageous to the manu- facturer of coal gas. A deviation from this mode was made by placing the fires in front of the retorts, but it failed entirely. The bottom retorts were soon destroyed—the action of the flame playing on the ends of them so forcibly as literally to reduce them into a state of fusion, when the fire was such as to keep the principal part of the retort at a bright red heat. Although retorts of various shapes had been tried at different establishments, we find no account of any having been set, save on the flue plan, that is, by the fire acting under the retort, and then returning over it on its way to the main ſlue, till the spring of 1817, when Mr. Rackhouse adopted a plan for heating re- torts of cylindrical shape set in ovens, a plan since known to the manufacturer by the name of the “oven-plan.” His first experiment was made at one of the gas-light establishments in London, by heating one retort in an oven. He next set two in one oven, then three, and afterwards five; and cylindrical retorts set in fives on the oven-plan are now by far the most general mode adopted at the different gas-light establishments. Mr. Malam's plan of oven retorts at the Westminster gas- works, perhaps, excels the former. Various have been the alterations made by different workmen in the fire-work to the retorts since the oven plan was adopted, but hitherto most have failed in remedying the very serious evils which must arise from their rapid destruction. Heretofore a retort of the same shape and dimensions, when constantly used night and day, lasted from eight to ten months; but, on the oven plan, the retort seldom remains in a working state more than as Indeed, so great has been the desire of making others from which much had been expected have failed so far as to cause the retort to be entirely destroyed in three or four Whenever coal may be submitted to distillation in masses of twelve inches diameter, the operation will be very tedious, and equally imperfect; the action of the red-hot retort upon the outer surface of the coal will soon decompose it, and therefore the gas in the first part of the process will pass over very rapidly—but then it acts against the process in the interior part of the cylinder formed by the coal in the inside of the retort; for as the outer surface of the coal is formed into coke, it becomes a coating to that which is within it, and through which the gas must pass ere it can extricate itself from the retort. Whenever such is the case, carbonization cannot be carried on to advantage, nor will it ever answer the most desir- able end. The great object which the manufacturer should ever keep in view, is by exposing coal to the action of heat it, thin strata, to obtain the greatest quantity of gas in the least time, and at the least expense, but such can never be effected by retorts like these. 364 G. A. S G. A. ST DICTIONARY OF MECHANICAL SCIENCE. Having thus glanced cursorily at the various modes which have been adopted for setting cylindrical retorts, it may not be improper to notice the rotatory retorts of Mr. Clegg's invention. In doing so, we are to observe that Mr. Maiben, of Perth, invented a retort for distilling coal by exposing it to the action of heat in thin strata. From his experience he learnt that the gas evolved during the first part of the process of carboniza- tion was of too aqueous a quality to be fit for combustion, and that evolved during the latter part thereof was so strongly impregnated with sulphur as to be highly objectionable. The retorts he made use of were of a square shape, and of a size 'sufficient to carbonize twenty-five pounds of coal, when spread in a layer of about two inches deep. The coal was introduced into the retort by means of a sheet-iron box, which was charged and slided in whenever the gas was extracted from the former charge, which, under such management, was generally accom- plished in two hours. But this description of retort being much too small to be serviceable in large establishments, led Mr. Clegg to construct a retort of sufficient capacity for car- bonizing about one chaldron of coals per diem. The first of them which was ever put up, (being eight feet six inches in diameter,) as were also the second and third, (each of twelve feet six inches diameter,) were worked under my observation. Each of these retorts contained fifteen boxes which slided into . the retort, upon iron arms, as described in the specification of the patent. Whilst the arms could be kept up, they were worked without much difficulty. The coal remained in the retort six hours, but was only one-third of that time exposed to the action of a red heat. Five boxes, having passed that, waited for the coal in the five boxes over the red heat being decomposed, which, on being done, the retort was opened, and those five boxes which had passed the red heat, were drawn, and fresh ones introduced upon the arms they had occupied, which process brought the five from the red heat to the situ- ation they had occupied, to wait there till the coal in the next five was decomposed, when the operation of change was again repeated; so that there were continually five boxes lately introduced into the retort, waiting to be brought over the red heat, five over the red heat, and five others ready for being withdrawn from the retort. Had not the expense of erecting retorts of this description been very considerable, and the wear and tear enormous, they would doubtless have been adopted in that establishment where they were first tried; but both were so much against them, that every idea of using them was there entirely relinquished. It is but justice to state, that those retorts produced gas at the rate of upwards of fifteen thousand cubic feet per chaldron (twenty-seven hundred weight) of coals; that carbonization was carried on at about sixteen or eighteen per cent. ; that the increase of coke on coal, car- bonized, was at the rate of fifty per cent. ; and, that the process of carbonizing, under those circumstances, was accomplished in about six hours. Mr. Maiben’s retorts were much too small for extensive manufactories; the rotatory one so very expensive, that it was not probable either would be brought into general use. To overcome the difficulties arising from the use of retorts, Mr. Malam proposed that elliptical retorts should be adopted, their length being about six feet six inches, their transverse diameter twenty inches, and their conjugate diameter ten inches. From retorts of such shape there was every proba- bility that the results, as far as related to the quantity of gas and coke obtained from a chaldron of coals, would be very similar to those from the rotatory retort; whilst the expense of setting them was but little more than would have been incurred by setting an equal number of cylindrical retorts, and not near so much as it would require to set such number as would car- bonize equal quantities of coals in equal times. The elliptical retorts had, however, one great advantage over the cylindrical ones, they were worked off in half the time; and five of them in action, worked with one bushel and a half of coals to each, during a few hours' charge, would produce as much gas in a day as ten cylindrical retorts worked at eight hours' charges, with two bushels to each retort every charge. The elliptical retorts on which my observations were made, were set in an oven and heated by one fire. - The semicircular retort, from its form, is likely to answer the manufacturer's purpose, if set with judgment, next to the rotatory and elliptical ones; that is, as far as the generation of gas and the production of coke are concerned; but, from its shape, its durability cannot be expected to be equal to the latter. The action of the fire upon the lower edges will very soon destroy it; for, it must be obvious, to any one at all acquainted with fire-work, how very powerfully the flame strikes upon any angular points. This, in the elliptical retort, is, of course, done away with, whilst the advantage arising from its shape is retained. - ‘. ‘. The square, or parallelopipedal retort, is twenty-inches in breadth, thirteen inches high, and six feet long, inside. It has a rib cast along the middle, on the inside of that part which is, when set, the bottom: This rib rises to the height of three inches, but does not approach nearer to the mouth-piece than about eighteen inches. It is for the purpose of strengthening the bottom of the retort, and preventing it from falling out of shape; but, when we consider the mode in which square retorts are set, it will not appear to be necessary. These retorts, when set six in one bed, and that number heated by one fire, are placed close alongside each other. The fire-place, being at one end of the range, is so contrived as to admit of the flue being carried under the whole range towards their mouths; it is then brought over the top of them, and again under and over in the like way, previous to its being allowed to enter into the main flue. Under this arrangement, square retorts, weighing about thirteen hundred weight, being set and worked at six hours’ charges, with one bushel and a half of coals to each as one charge, at such a heat as causes ten thousand cubic feet of gas to be generated from a chaldron of Bewicke and Cras- ter's Wallsend coal (twenty-seven hundred weight), are found to remain serviceable one year. The carbonization is, when they are once brought to a working state, carried on at about twenty-five per cent. ; but they require to be fired for a fort- night or three weeks before they are at a proper temperature for carrying on that process. - The disadvantages which attend the use of those retorts are, first, that they are more expensive in the first instance than cylindrical ones: secondly, the length of the ſlue passing under and over them being extensive, and of but small dimensions, it frequently becomes choked up, and requires, for clearing it out, various openings. When, therefore, it is found necessary to examine those flues, it generally happens that the heat of the retorts is very considerably decreased; and when we con- sider the time requisite for heating them in the first instance, we must be aware that such a diminution cannot be overcome but by a considerable expense of fuel, and carrying on the process very unfavourably and imperfectly. Lastly, when the retort is burnt out, the cost of replacing it is nearly equal to the first cost of setting; whilst, in using cylindrical ones, a retort is generally replaced for about three-fifths of its first COSt. . . On the 5th of August, 1817, a patent was obtained by John Perks, for an arrangement such as to cause thirteen retorts, each capable of carbonizing a bushel and a half of coals in six hours, to be heated by one fire. The retorts are ‘so placed, that, when the observer stands in front of them, twelve of the number form a circle round the thirteenth, which is cylindrical, the centre thereof occupying the position of the common centre of the surrounding ones. The shape of these retorts will be best understood by supposing two circles struck from the centre of the mouth-piece of the thirteenth retort; the inner one forming one side of the series of twelve, and the outer one the other. If, then, either of these circles be divided into twelve equal parts, and lines drawn from the inner to the outer circle, radiating from their common centre, the transverse vertical section of them will be exhibited. It is evident, that, under this arrangement, they form a complete circle of large diameter. The mouth-pieces are formed like those which are used with the square retorts, and, of course, the conducting pipes and pipes leading to the hydraulic main, are nearly similar to those used for either cylindrical or square retorts. The fire-place is in front of these retorts, and as they are all enclosed in a circle of brick-work, which is divided into four equal parts by fire lumps laid horizontally, and so brought out of the circle as to be in contact with the adjoining retort; and that part which is TVOC). JLIJ º NITTILSIGI IO I SINIC), Iºlº LIE) II swº º ºg º ºn tº - - º - - - */. % º º º 2%º º 2 */* %2 */ (...) 2” % º” º 7 º *% ºº - - º- ºº/ % º */ º/// (* * º,º º Z” */ %/*/ * * * *%- /*% º */ º Zºº” º º Cl - - º º - - - - - pºp - p = p + 2 2 ºr - - I ºr ºr G. A. S. G. A. S. 365 Diction ARY OF MECHANICAL SCIENCE. between the central retort and the others, being divided in a similar way, the action of the fire is under three, and then, turning over their ends, it comes over them towards their mouths, where it finds an opening leading above the next three; and, passing their ends downwards, it is brought towards the mouths a second time, and so on in like manner, till it has traversed round the whole series, when it passes into the main flue. Description of the Method of setting two cylindrical Retorts on the Flue plan, so as to be heated by one Fire—Fig. 1, represents a front view of two retorts set to Fig. 1. Fig. 2. one fire on the flue plan. In it, the manner in which the conduct- ing pipes are connected to the retorts is exhibited : these lead to the hydraulic main. Fig. 2, is a vertical section of the same retorts, supposed to be drawn about midway of their lengths. In this section a repre- sents the end of that part of the flue leading from the fire under the lower retort, which rises near the mouth-piece thereof through the openings b b, and, passing between the two retorts, rises over the end of the upper one; and, being brought over the top of it, by means of an opening c, about nine inches from the mouth-piece, enters the upper flue, and thence passes into the main one. ddd are end sections of the fire-tiles; on Fig. 3 the two lower lines of 5 * *- them the retorts are supported, and the upper one forms the base of the top flue. Fig. 3, exhibits a longitudinal section of these retorts. In it, a is the fire-place, b a section of the fire- bars, and c the ash- pit. The direction taken by the flue is pointed out by small arrows. Description of the Method of setting sir parallelopipedal Retorts, so as to be heated by one Fire.—Fig. 1, represents a transverse section of parallelopipedal retorts, in which six are heated by one fire. These retorts are twelve inches square inside, and Fig. 1. six feet in length. The fire-place a with the ash-pit b is placed at one end of the series, but so as when the observer stands in front of the retorts he shall be in front of the fire-place also. Under this arrangement, the retorts 1 and 6 heat the best, and tº the worst. If the reader compares the situation of the flues, as exhibited in fig. 2, he will observe that there are four which ºommunicate with the fire-place. These are divided by lumps laid edgewise across the whole series of retorts, forming the ſlues marked dddd, fig. 2. This range of flues is covered by fire-tiles, and upon them the retorts are placed close alongside of each other. Over the top of the retort is a range of flues eeee, Fig. 2. which corresponds with the lower ones, and these are covered with fire-tiles and of course with fire-bricks. Upon the latter is a third series of flues of about two-thirds the depth of the former ones, and these rise by the open- ing f, fig. 2, into the main flue. In fig. 1. the transverse direc- tion of the flues is shewn by the arrows leading from the fire-place. The mouth- pieces of these retorts are circular, as shewn upon retorté, fig. 1, last column. Fig. 2 represents a longitudinal section of these retorts, in which the ſlues and action of the fire have already been described. A is the retort, a the fire-place, b the ash-pit, and c the fire-bars. Description of the Method of setting five cylindrical Retorts in one Owen heated by three Fires, with Sections of the hydraulic Main and Dip-Pipes, as exhibited in the Plate of GAs Light Re- toRTs.-Fig. 1 represents a front view of the retorts A A. A. A. A. as set and in a finished state. In it the two upper retorts are shewn without the lids of their respective mouth-pieces: the two outer lower ones with the lids on, but without their being secured by the cross-piece shewn upon the middle one. The bed of these retorts is supported by an arch of brick-work, marked BB. It is brought so far forward as to allow room enough for the stokers to charge and draw the retorts, and for a sufficient quantity of coals to be kept for supplying two or three charges, with fuel for present use, luting, tools, &c. Im- mediately in front of the retorts is introduced, instead of part of the key-stone for the arch, a cast-iron frame of about three feet and a half long, and two feet broad at the top, with an iron door ſitted to it. The bottom of the frame is struck to the radius of the arch, and of course the sides taper inwards in proportion to that radius. The situation of the opening is expressed at C. This opening is for the purpose of allowing the red-hot coke when drawn from the retort to fall into the archway at D. a a a, the doors of the fire-places, bbb the doors of the ash-pits. These doors are furnished with three perpen- dicular slits of about two-thirds their length and five-eighths of an inch in diameter, for allowing a current of air to pass to the fires. The dimensions of these slits can be decreased by another piece, made with openings to correspond, which slides horizontally in grooves in a line with them, so as to regulate the admission of air to such a degree as the operator may desire, cc cle c are the conducting pipes which convey the gas as it is evolved from the retorts towards the hydraulie main. did ddd front sections of the H pipes, eeeee, front sections of the dip-pipes, with the saddles through which they are bolted to the hydraulic main. E the hydraulic main, F the main pipe for conveying the gaseous and other products evolved towards their respective reservoirs. G. G. G. G. cast-iron columns fitted with crutches at the tops of the upper ones for supporting the hydraulic main. Fig. 2 is a section of the same retorts, which supposes them to be cut through from the top to the bottom about the middle. In this section, the hydraulic main, dip, and conducting pipes, are not shewn. A A. A. A. A the retorts. a a a wa a, such part of the arch forming the oven and brick-work contiguous to the fire-places, all of which require to be constructed of Welsh fire and arch bricks. The crown of the oven is flattened by means of Welsh fire-tiles as at b. At the extreme end of the oven are two openings, which lead into the two small flues ec. These ſlues pass above the top of the oven towards the front of the retort, and then each turns towards the centre flue d, which having entered, that one leads towards the main flue H, which it enters through the opening e. fff are the fire-places, and g g g the ash-pits. h. h. h. are fire-lumps placed beneath the lowermost retorts, for protecting them from the action of the fire. The two upper retorts are supported near their middle by wrought-iron belts, which are brought through the upper part of the oven, and passing through a cast-iron bearing bar 5 A 366 G. A. S G. A. S. DICTIONARY OF MECHANICAL SCIENCE. placed above. it, are secured, by means of nuts, in the situ- ation wanted. When the oven-plan was first introduced, the retorts were supported by cast-iron props bedded in the brick- work, crutch-shaped at the top, and rising to a proper height to receive them. They are not now used, and therefore not shewn in the plate. º - * Fig. 3, is a longitudinal section of cylindrical retorts set on the oven plan. A A are the retorts, the mouth-piece of the lower one being secured by the lid and cross piece ; the upper one is shewn without the lid. f is the fire-place, with the posi- tion of the grate-bars. . g is the ash-pit. The action of the fire is the same in this section as has been already described by fig. 2 : the flame having exerted its force in the oven, rises by the opening shewn at the extreme end of the retorts, and passes along the flue towards their mouths till it comes to d, when it enters the middle flue lying parallel to the flue c ; that leads into the rising part e, and thence into the main flue H. h is the conducting-pipe which conveys the gaseous and other pro- ducts from the retorts to the H pipe i, and that carries them into the dip-pipe k, which enters into the hydraulic main E. In this section of the hydraulic main, the fluid by which the dip-pipe is sealed is shewn as at l, through which the gas bubbles up as it is evolved, and passes along the upper part of the hydraulic main towards the main pipe F (as shewn in fig. 1) on its way to the condenser. The hydraulic main is supported in this section in a similar way to what was shewn in fig. 1; but instead of a brick arch for supporting the floor in front, m is one of a range of beams for supporting a cast-iron floor. m is the opening for allowing the coke when drawn from the retorts to fall on the floor o. This opening is covered by an iron door, which is closed at all times, save when the retorts are drawing. Description of Mr. John Malam's Method of setting Five of his Blliptical Retorts in one Oven heated by three Fires, with Sec- tions of the Hydraulic Main and Dip-Pipe, as exhibited in the Plate of GAs LIGHT REToRTs, Figs. 4, 5, and 6.—Fig. 4 repre- sents a front view of the retorts, as set and in a finished state. The arrangement of the retorts, hydraulic main, dip and H pipes, being nearly similar to that described above, a repetition of description is not necessary here: we shall, therefore, only describe such parts as differ from the former mode of setting. In front of these retorts is a cast-iron plate AAAA, against which the flanch of the retort rests. At each corner of this plate is a hole for receiving a bolt. This passes through the brick-work to the back of the retorts, which is supported by a plate of similar dimensions to that in front, cast with openings opposite the end of each of the retorts. These openings are secured by plugs, which are removed when it is requisite to replace a retort that may be worn out. In it are also openings for the sights. The bolts stated to pass through the front plate pass through this also, and both are secured together by screw- ing up their respective nuts. Under this arrangement, it is not necessary to disturb any of the brick-work, when, from a retort becoming ineffective, it requires replacing. The fires for heating these retorts are placed at their back. Fig. 5, is a section of the same retorts, which supposes them to be cut through from the top to the bottom about the middle. a a are fire-lumps placed edgewise so as to divide the distance between the exterior lumps b b into three requal parts corre- sponding with the fire-places. c c c are the ends of the arches over the respective fire-places as they meet the dividing lumps a a. ddd are three fire-tiles resting upon the lumps b a a b : these tiles form a bridge from one side of the oven to the other. e e fee is a section of the oven, the rising part on each side marked ee being constructed of Stourbridge arch bricks, and the flattened part f of Welsh lumps or fire-tiles. g g are sections of the two horizontal flues which rise near the mouth f the retort, and pass towards the main flue. Fig. 6 is a longitudinal section of elliptical retorts set on Malam's plan. A A are the retorts. b is the fire-place, c is a section of the grate bar. The lower edge of this bar is cham- fered off and of a circular form. It is of sufficient depth to allow the action of the cool air through the ash-pit to have full effect upon it, thus preventing the very rapid destruction which generally attends cast-iron grate bars. f is the ash-pit. a is a section of the lump for dividing the flames from the different fire-places. d is a section of the tiles which form the bridge. The flame acting under the arch c, as expressed in this and the former figure, passes between the dividing lumps under the range of tiles d, and there divides itself in the direction of the two arrows, by this means causing the heat to act uniformly in the oven. h, and rises at i, preparatory to entering the main flue. retorts are cast with a cylindrical projecting end, which is received into the brick-work: they are also supported by cast- iron props (bedded in the brick-work beneath them) crutch- The opening flue is expressed at g—it passes along These shaped at the top. The section of the hydraulic main, dip, and H pipe, as also of the floor, is the same as shewn in the sec- tion of cylindrical retorts set on the oven plan, page 365, to the description of which our readers are referred. The annexed figure, is a transverse section of the couplings which sur- round the retort when it is set. The face of the couplings is brought close up to the flanch of the retort. In the following figure, a a is a longitudinal section of the couplings, they are - wedge-shaped. A is a section of part - of the retort. , b b the iron plate in front of the oven, cast with flanches verging inwards so as to fit to the couplings when brought to their places by the flanch of - the retort coming close to the plate. - - c c part of the brick-work in front of the oven, so angled off as to allow the heal to approach as near the mouth- piece as the couplings will permit. When this plan is adopted, it is evi- dent that, by introducing the couplings nearly to their places, and bedding them in cement, the bringing of the retort to its situation in the oven will force them up, and form a complete joint round it. On the contrary, when a retort becomes defective by displac- ing the plug opposite to the end, and bringing a purchase upon that end by means of an iron bar, (the joint between the mouth-piece and gas conducting pipe being first broken) it will be forced out of the situation it had occupied, and loosen the couplings. When the retort has been moved about a foot, they may be taken away, thus leav- ing sufficient room for the retort to pass: it may be drawn out by a purchase made fast to an eye-bolt in the wall opposite thereto, and a new one introduced into its place, the whole operation being performed in two or three hours. Mr. Pechston's TABLE, exhibiting at one View the Advantages and Disadvantages which arise to the Manufacturer from the Use of different Kinds of Retorts variously worked. §ºf • 2. ſº N. ſº % iſ: | Z --> % | à? % º Reference º Usual ãº. ;:# Per Centage jº, to . P#. Charge in for. dron, the retort at º the Mode Descrip- in Days. I}ushe's working being worked Carboniza- of setting tion of of 84 lbs. off one at a briyht red £ion is car- fité Ivetort. each. Charge. | heat. ried om. Itetorts. Cubic Feet A 270 2 8 10,000 20 0. A 180 | 13 || 6 9,000 30 l a A 180 1} 4 8,500 30 (! A | 80 2 8 9,000 25 b A 120 I} 6 8,500 33 b A 120 1+ 4 8,500 35 | b . A ! 80 2 8 10,000 25 to 50l c A. 120 1} 6 9,000 do. C A 120 1% 4 8,500 do. C B 63 2 .8 10,000 16 to 40 d B 42 1} 5 9,000 do. d C 270 13 4 15,000 30 € D 300 13 || 6 10,000 25 f' In the first column of the foregoing table, from A is to be understood that the results expressed in a line with that letter G A s G. A. S DICTIONARY OF MECHANICAL scIENCE. 367 arise from the use of cylindrical retorts of the dimensions, &c. as hereafter mentioned, that is to say,+Dimensions, 63 feet long, 1 foot diameter inside; weight, 10 cwt. 2 qrs. ; price, per ton, £12; first cost of setting, including retorts, brick- work, labour, hydraulic main, and connexions, with coke hearth, complete, £23; cost of replacing one that may be worn out, £15. - • - . - Those marked B in the first column are of the same dimen- sions, price, and weight. º Those marked C are elliptical, and of the following dimen- sions, &c.:—Length 63 feet; transverse diameter inside, 20 inches; conjugate diameter inside, 10 inchest weight, 13 cwt. 2 qrs. ; price, per ton, £13; first cost of setting, including retorts, brick-work, labour, hydraulic main, and connexions, with coke hearth, complete, £25; cost of re-setting, when the oven in which they are placed requires to be rebuilt, £18. Those marked D are parallelopipedal shaped, and of the fol- lowing dimensions, &c.:—Length, 6 feet; breadth inside, 20 inches; depth inside, 13 inches; weight, cwt. 13; price, per ton, £12; first cost of setting, including retorts, brick-work, labour, hydraulic main, and connexions, with coke hearth, complete, £21; cost of re-setting, £18. - The letter a in the last column of the table, implies that the results opposite thereto are from retorts set on the flue plan, two being heated by one fire at the back of the retorts. The letter b in the same column, retorts set on the flue plan, three being heated by one fire in front of them. The letter c,-retorts set on the flue plan, and four being heated by one fire at the side opposite to their mouths. The letter d, retorts set on the oven plan, five being heated by three fires immediately beneath the front of them. The letter e implies that the retorts are elliptical and set on Malam's plan, five being heated by three fires at the back of them. The letterf relates to parallelo- pipedal retorts, twelve being set in one bed and heated by two fires; the flues passing under and over six retorts from each fire. . - When cylindrical retorts are set two to one fire, so as to produce, when worked at a bright red heat, in the proportion of 10,000 cubic feet of gas to a chaldron ; if the temperature be decreased, they will not produce much more than 8000 cubic feet to the chaldron; but their durability will be extended to twelve months; and such decrease of temperature under any of the arrangements exhibited in the foregoing Table, when working cylindrical retorts, will cause a proportionate decrease in the quantity of gas generated, and an increased durability to the distillatory vessel. Whilst cylindrical retorts, worked at a low temperature, are producing but 8000 cubic feet of gas from a chaldron of coals in eight hours, the rotatory retorts would in six hours produce from 15 to 16,000 cubic feet of gas from the same quantity of coal; and the elliptical retort from 14 to 15,000 in four hours. When cylindrical retorts are set on the flue plan, and four heated by one fire at the back, should they be fitted with Mr. Peckston's apparatus for removing a defective one, they would always work eight hours’ charges of two bushels to each retort at 25 per cent., producing 10,000 cubic feet of gas to the chaldron ; and, when worn out, might be replaced for about seven pounds each. - Carbonization.—Were it requisite to go into calculation upon the different modes of working the retorts, taking the results of experiments made at different times and under various circum- stances as data, it might be most clearly proved how much in all cases the longer process excels the shorter. In order, in some measure, further to elucidate this point, to observe, that whenever pit coal is to be submitted to the process of distilla- tion, the time for the process cannot be shortened to less than eight hours, unless we have the means of exposing the coal to the action of heat in thin strata, say four inches; and when coal is so exposed in cylindrical retorts, that retort which, when worked at the eight hours’ process, is capable of carbon- izing two bushels of coal, would only carbonize about three- fifths of a bushel. The segment of a circle, whose altitude is four inches, and chord eleven inches and a quarter, bearing such proportion to the capacity of the retort, the diameter of which is about twelve inches. We are told by those who have the management of carbonizing in different manufactories, that difficult to find a better. when the six hours’ process is adopted, the charge is from a bushel and a quarter to a bushel and a half. In such case, the mass of coal is by no means sufficiently diminished so as to cause the process to be performed with advantage. When the retort is so charged and worked, the heat verging from all directions towards the centre, will meet with nearly the same obstacles to prevent the extrication of the gas, as if it had been fully charged. . . With respect to these shorter charges when worked off by cylindrical retorts set on the oven plan, the same arguments which have been already advanced will hold good in favour of the eight hours’ process, but with considerably more weight, inasmuch as the wear and tear of the retort will be propor- tionably greater. We may, therefore, from what has been said, draw this conclusion, namely, that whenever cylindrical retorts are used, let the mode of setting be what it may, the operator ought never to work off his charge in less than eight hours, and that with such heat as would produce from one chaldron of Newcastle coal (twenty-seven hundred weight) the average quantity of ten thousand cubic feet of gas. • , When semicircular or elliptical retorts are used, either will admit of the charge being worked off in much less time than can be effected with cylindrical ones. Tor, in using the first, it would be advisable to introduce the coal into the retorts by means of sheet-iron trays nearly of their length and breadth, and about four or five inches deep. By having two sets of trays for the retorts in action, the time usually lost in charging would be greatly decreased, as would also the stoker's labour. By the mode most generally practised, the raking the ignited coke out of the retort is not only very laborious, but also at- tended with much Joss of time, both which would be avoided by the mode suggested; for by using the trays, the spare ones might be charged with the proper quantity of coal preparatory to the time for drawing, and by that means almost the only time occupied in the operation would be that required for breaking the joints of the mouth-pieces, and making them good again. Carbonization, when carried on by means of semicircular retorts, if properly set, has a decided preference over cylindri- cal ones;—for, as the great art of making gas to advantage, depends upon exposing coal to the action of heat in thin strata, such kind of retorts are particularly adapted to the purpose. They have, however, one disadvantage, which has not passed unnoticed. The action of the flame upon the angles at their base, tends towards destroying them with considerable rapi- dity. To guard against such destruction, the angular part has been rounded off so as to present an arc of a circle to the fire, instead of an acute angle, and such alteration was doubtless for the better. Were such retorts set on the plan of an air- furnace, in which every part of them could be regularly heated, without directing the heat more forcibly against one particular part than another, they could hardly fail of answering a very desirable end to the manufacturer of coal-gas. From the numerous experiments made on the distillatory process, on the plan of submitting the coal thereto in thin strata, it can hardly be doubted but retorts of this description, if set with judgment, would remain serviceable from six to eight months, being charged every four hours, night and day, with two bushels of coal each, and worked at such heat as to produce from a chaldron of coals the average quantity of thirteen thou- sand cubic feet of gas, with an increase of coke, (particularly adapted for parlour fires, as well as culinary purposes,) of 40 per cent. upon the quantity of coal carbonized; consequently, that five retorts of this description would produce as much gas during the space of twenty-four hours as would require twelve cylindrical retorts to be worked at eight hours’ charges with two bushels of coals to every charge, or sixteen cylindrical retorts worked the same time with a bushel and a half of coals to each retort for one charge. - As what has been said on the subject of carbonization when carried on by means of semicircular retorts, is in almost all respects applicable thereto when square retorts are used, it therefore will not be necessary to take up the reader's time by speaking of it here. The next mode of carrying on the process of carbonization is by means of elliptical retorts, for which purpose it would be The elliptical retort combines in it 368 G. A. S G A s pigTIONARY OF MECHANICAL SCIENCE. the durability of the cylindrical one, with the advantages obtained by exposing the coal thinly to the action of heat upon a large surface, and therefore, when it is used, the process will be accomplished in about four hours. . Upon retorts of this description I have had opportunities of making observations, the result of which leads me to pronounce such well adapted for promoting the interests of the manufacturer. Five ellip- tical retorts are capable of carbonizing forty-five bushels of coal per diem, and of generating from that quantity of coal about seventeen thousand cubic feet of gas, or at the rate of fourteen thousand cubic feet per chaldron. From one chaldron of coal, when elliptical retorts are used, will be produced a chaldron and a half of saleable coke. The elliptical retorts on which my observations were made, were set five to one fire, and so well was the heat disposed of, that from one end to the other they remained, whilst in action, at a bright cherry red- ness; being kept so night and day for more than ninety days, they were not much injured,—from their appearance, there could be little doubt but they would remain serviceable nearly twelve months. They were charged and drawn in the usual way; but notwithstanding the charging and drawing was more frequent, the stokers found it more easy to work them than a like number of cylindrical retorts. Their shape allowed room to rake out the coke more rapidly than could be done from those of a cylindrical form, and the coke not being so compact when produced in the elliptical retort, required considerably less labour to clear it from thence. It would be no exaggera- tion to state the results, arising from the use of these retorts, to bear similar proportions of advantage over the cylindrical ones, to those stated when speaking above of semicircular- shaped, retorts. The annual expense of cylindrical retorts, when worked at eight hours' charges, together with the wear and tear of grate- bars, is stated to be £2360, when worked to produce 44,598,684 cubic feet of gas. When elliptical retorts are used, one retort will remain in a sound working state about twelve months; if, therefore, we calculate the expense of elliptical retorts, with their appendages, for one year, and compare the various results together, we shall find how far they are advantageous:-- By using elliptical retorts, worked at the four-hours’ pro- cess, it would require about forty retorts to be kept constantly at work to produce 857,667 cubic feet of gas per week,--such retorts so worked would remain serviceable twelve months, consequently there would be but forty burnt out in a year,< the cost of replacing each being £18, amounts to . . . . $720 00 Wear and tear of grate-bars, . . . . . . . . . . . . . . . . . . . . 60 00 £780 00 Expense of cylindrical retorts, &c. for one year, when worked at the eight-hours' process, so as to obtain 44,598,684 cubic feet of gas, is £2360 0 0 Elliptical retorts as above, . . . . . . . . . . . . . . . . . . 780 0 0 Balance in favour of the elliptical retorts, ..... £1580 00 Annual balance in favour of working elliptical retorts as above described, over cylindrical ones at eight hours' charges, as far as relates to coals, products, and labour, . . . . £1135 1 33 Ditto, as far as relates to the wear and tear of retorts, grate-bars, &c. . . . . . . . . . . . . . . . . . . . . . . 1580 00 The sum........................ $2715 1 34 is the total annual balance. The annual balance in favour of working cylindrical retorts at eight hours' charges over charges of six hours, when required to generate by either, 44,598,664 cubic feet of gas in a year, was stated to be . . . . . . . . . . . . . . . . . . . . . . . . £5511 16 10 Therefore, if to this we add the balance as above in favour of elliptical retorts, ....... . 2715 8 33 we have. . . . . . . . . . . saved in one year by using elliptical retorts, in preference to carbonizing with cylindrical ones, let them be set as they may, if worked at six-hours' charges, with a bushel and a half of coals to each as an average charge. .....:88226 18 l; Hydraulic Mains and Dip Pipes.—By the term “Hydraulic Main,” as used in the gas-light establishments, is understood that cast-iron pipe which is supported by columns in front of the brick work enclosing the retorts. It is so situated, as to lie parallel to the top of that brick work, at a distance of from twenty inches to two feet from it. Its use is to receive the “Dip Pipes,” through which the gas, as it is evolved from the retort, passes, together with the other products, on its way to the condensing main, or to the vessel employed for condensa- tion, as the case may be. The diameter of the hydraulic main is various in different establishments; in some it is ten inches, in others twelve or fourteen. In works where not more than from forty to sixty cylindrical retorts, six feet and a half long, and one in diameter, are set in one retort-house, a diameter of twelve inches will be sufficient. . It is generally constructed of flanch pipes, in lengths of nine feet each. One end of it is closed by a blank flanch so as to be perfectly air-tight, the other has a semiflanch placed across it, of sufficient height to prevent the liquid introduced into the main from sinking below a certain level;-it is of advantage, that similar semifianches be placed between every length of pipe forming the hydraulic main. These flanches should rise two inches and a half above the line of the bottom of the dip-pipes; by such means, the gas, as it is discharged from the retort, will always have to pass through such depth of fluid, before it can enter into the hydrau- lic main. The use of the hydraulic main, as has been already stated, being for receiving the dip-pipes, we are to consider what end they may be...intended to answer. . A section of the hydraulic main, with the most approved dip-pipe, is given in the Plate, fig. 2. The dip-pipe is about two feet in length, and three inches diameter inside; at the top is a socket for receiving another pipe of the same diameter. At about eight inches from the spicket-end of the dip-pipe is a circular saddle of about nine inches diameter, cast to the radius of the exterior surface of the hydraulic main. This main being tapped for the reception of such a number of dip-pipes as there are retorts to work into it, they are jointed upon it by means of iron cement in the usual way; when that is done, it is evi- dent that the range of the spicket-end of these pipes will equally descend, and of course, supposing the hydraulic main to be placed perfectly level, which it always ought to be, should one of them be immersed two inches and a half in any liquid that it may contain, each one of the range will be so. Now, when it is considered, that if there were not some con- trivance for preventing the gas returning from the main pipes towards the retorts, when the mouth-pieces are removed in the operation of drawing, either by stop-cocks on each of the “gas. conductors,” or other means, the process would not only be very wasteful, but extremely hazardous; for, as the gas would be passing over by means of the conducting pipes to the hydraulic main, in a range of sixty retorts, from fifty-two of them, whilst eight were drawing, it would follow that the whole quantity of gas then generating would escape at the mouths of the retorts that had their lids taken off, and burst forth with such a flame as no one could come near; if not attended with still more serious consequences by the admission of atmosphe- ric air, which might cause the most violent explosion. The necessity of means being adopted for preventing such things happening, is obvious; and a more simple, and at the same time safe, method than that of the hydraulic main and dip-pipes could hardly have been thought of ; for, had stop- cocks been used, they would have been attended with consi- derable troublé, and always liable to get out of order, so much so, that no dependence could be placed upon them; for the tar and ammoniacal salts would, in a few days, so clog the plugs as to render them immoveable. If the pressure upon the hydraulic main from the purifying vessel be greater than the distance between the bend of the H pipe and the spicket-end of the dip-pipe, in the hydraulic main, the gas, after having once entered that main, cannot be forced back to the retort. By the pressure from the purifying vessel, is to be under- stood, the depth of lime in solution through which the gas, after entering it, has to rise through before it can escape to the gas-holder, the most usual depth of the purifying mixture through which the gas bubbles up in purification being ten ^2 / 2. * > * - - - - ^ , º, - % /// º (, Z% º ºp- ºve ºoº. º Lº& ºf Palmer's fºrwºer. Perk's condenser 7. ſº PATENT == -- - * || London. L. ºf ſº | | Published by H ºne-ºn-cºcººn sº G. A. S G. A. S 369 Diction ARY of MechANICAL science. inches, the purifying vessel is said to be worked at ten inches' pressure. The length of the dip-pipe is two feet; from the top of it to the centre of the bend part of the H pipe, about six or eight inches: more, making altogether about two feet and a half; consequently, before the pressure in the lime vessel can be of sufficient power to force back the gas from the hydraulic main through the conducting' pipes to the retorts undergoing the operation of drawing, it would require to be three times greater than what the vessel is usually worked at. - The main, of which we speak, with the dip-pipes, form a series of hydraulic joints, than which, in the manufacture of so elastic a fluid as coal-gas, nothing could be so well adapted,— nothing could be so safe. - - - - . . . . . Accidents have been heard of, occasioned by the gas in the hydraulic main exploding, and forcing the gians from the top of the pipes perpendicular thereto, (usually called the H pipe, from its similarity to that Roman letter,) but such accidents must have arisen from great carelessness on the part of the operator, or from the clogging up of the purifying vessel. The condensing Main, and various Methods of Condensation.— The gas, when evölved, běifigiúixéâ with tar and ammoniacal fluid, in a state of vapour, which pass over with 'it from the retort to the hydraulic main, it becomes necessary, that, as much as possible, these two products should be condensed and lodged in the proper receptacle before the gas reaches the purifying vessel. In order that this condensation may be properly effected, the products generated should be exposed to a large surface of some cold body on their passage to the purifier; by this means the tar and ammoniacal liquor are separated in a great measure from the gas, and, being of so much greater density, fall to the bottom of the pipes, and drain from thence to the vessels appropriated for their reception. The gas is also cooled, and made much more ſit for the lime to act upon than if it were brought directly from the hydraulic main to the lime vessel in a hot state ; for, whenever it is so, it is impregnated with the tar and oleaginous particles, which very soon render the purifying mixture useless. The consequence following is, that a much greater portion of lime will be required for the purifying process, or otherwise that the gas will pass through the lime vessel into the gas-holder, without being acted upon. The use of impure gas ought, on all occasions, to be avoided, for whenever it is used, it is almost impossible to obtain a good light; when it is submitted to combustion it is smoky, and emits a disagreeable odour; the plugs of the stop-cocks on the fittings in houses become choked up with tar, which, however surprising the case may be, has been found in situa- tions at a mile and a half distant from the manufactory, after having passed through various pipes of different sizes and at different levels. - - - Experience having taught the manufacturer the necessity of attending to the subject of condensation, he, of course, adopted such means as he considered most advisable for accomplishing it. In some manufactories it was thought that the gas would be sufficiently condensed, from its being conveyed from the hydrau- lic main by a pipe laid in a direct line from the retort-house to the purifier—in others, the gas was conveyed to the lime-vessel through a worm-pipe placed in the tank of the gas-holder—and again, in others, by a range of pipes laid parallel to each other at a considerable depth, and with a certain declivity from one end of the works to the other;--whilst some, in addition to these contrivances, proposed a tank, into which the range of pipes, as last specified, should convey the gas at the bottom, and by means of a contrivance something similar to the shower- bath, have it washed there before it could make its exit towards the purifier. Most, if not all, of these modes, have been tried by different operators, and have been found more or less effective. • Malam's condenser is also a square cast-iron vessel, about nine feet long, five wide, and four deep. Into this vessel are introduced plates at the distance of from six to eight inches from each other, with raised edges of about three inches in height; these are bolted to the sides of the vessel, and are per- fectly parallel to each other; they are in length about eight feet six inches, so that being secured to the sides of the vessel and one end of it, the other end will be at the distance of about six inches from that end of the vessel to which it is contiguous. The lowermost of these plates being connected to one end of the vessel, the next plate above it will be connected at the end opposite thereto—the third plate the same as the first—the fourth as the second, and so on alternately till all the plates are fixed. This being done preparatory to bringing the condensing vessel into action, water is introduced at the top, which filling the uppermost shelf to the height which the projecting part of it allows, it runs over and fills the second, from thence the third is filled, and so on till the whole range is so. From con- sidering this matter, it is evident, that if the entrance, pipe be at the bottom of the vessel to the right, should gas be introduced there by means of it, it will pass over a sheet of water equal to the area of the lower shelf, and as the next shelf above ap- proaches no nearer than six inches to the end towards the left, it will by that opening rise above it and pass towards the right, where it will find an opening from the third shelf, and so it will pass alternately to right and left till it reaches the exit-pipe placed at the top of the vessel. The condensible products are carried from the respective shelves by means of small bends projecting from one end of this vessel; but as I am of opinion it will be likely to answer the purpose of the manufacturer both as relates to its first cost, durability, and action, I shall describe a condensing vessel of this kind, capable of performing what is required, where about 100,000 cubic feet of gas are gene- rated daily. - The condenser we have just described, has undergone several alterations; we therefore shall proceed to describe Malam’s im- proved condensing vessel, as exhibited in the Plate. A B C D, fig. 1, is a longitudinal section of this condenser. The vessel is a parallelopipedon made of cast-iron plates, supported upon a bed of brickwork. At about one foot from the bottom is a range of plates, a a a a, together of the same dimensions there- with, which are jointed to the side of the vessel. Upon these stand a row of plates of the same material, one of which is shewn, as at E. Their bases occupy such situation as is ex- pressed in the plan A B C D, fig. 2, of the hydraulic main. In that plan, the pipe which conveys the gas into the condenser is shewn at E; having there entered, it passes between the up- right plates in the direction of the arrows till it reaches the exit-pipe F, and that pipe leads to the purifying apparatus. It is to be noticed, that these upright plates do not rise to the top of the condenser—there is a space of about six inches left between it and the plate which fits over them. The entrance and exit-pipes E and F are placed about a foot from the top of the vessel, as shewn in the transverse section, fig. 3. The range of cast-iron plates, a a a a, in the hydraulic main mentioned above, do not lie perfectly horizontal, but with a small declivity to the right, by which arrangement the condensible matter drains towards the openings a b c, fig. 2, and thence by the pipe a, shewn in the figure of Mr. Malam’s condenser, and a b c, ſig. 3, is discharged into the receptacle E, which runs across the vessel, and is filled with water for the pipes to dip in, and form an hydraulic joint. It follows, therefore, that as the condensible products accumulate, they overflow the parti- tion which forms the part F, and run into the chamber G, from whence, when it is necessary, they are drawn off by the cock H, in the two figures of the hydraulic main, and the condenser. A B C D, fig. 2, is a plan of this condenser, the arrangement of which is already described ; and fig. 3 is a transverse section of the same vessel. The following are different sections of the condenser, for which Mr. Perks obtained a patent:—The first figure is a plan of the top, shewing the situation of the bend- pipes, &c. Fig. 2, is a plan of the underside of the plate, on which the upright pipes are supported, shewing the openings into the lower chambers, and the position of the upright partitions. - - Fig. 1, in the next page, is a side view (in elevation) of the vessel, the side plates being supposed to be removed. The pipe and bend beneath are for carrying off the condensations. The dotted line shews the height at which the fluid will be con- stantly kept in the vessel. An opening is made, or left at the bottom of each partition, which allows the condensed matter to flow from one to another, and to be carried off by the pipe. Fig. 2, is an end view of the vessel, (in elevation) the plate being supposed to be removed. In considering the merits of either of these vessels, the most 5 B 370 G A S G A S DICTIONARY OF MECHANICAL SCIENCE. striking are the facility with which any obstruction to their operation may be removed, and the very efficient means they afford for answering the purpose of the manufacturer, as far as relates to the gas generated, being well condensed before it is brought to the purifying apparatus. We have already stated the distance which the gas would have to travel in passing through a condenser constructed on Perks’s prin- ciple ; and, when we consider that the pipes therein are always surrounded by cold water, we can hardly doubt of its Fig. 1. Fig. 2. f | i gºla-sº ſº º I. } f : # . º º | º # º º | | | | § # º ; | | | | | || | i i º: º C º º AP ; 3. º af º ſº º º : : § . & * :t : º º 2. § ###. ######### Fi-i-Hi l-i- * N § || E={}=== § E. : *FHS # ##| Hä N t Pººr, a zz grear aſ a , z º.º. 42 - ºr, a zºº -a a tº a Af 2. º sº 42 3' | Jill - £ 3: j effect. In his vessel the bends at the top are easily removed in the event of any obstruction presenting itself, and by forcing down each of the pipes a rod for the purpose, the passage is cleared. As there is a sufficient opening left at the bottom of each of the partitions in the lower vessel, the obstructing matter can be withdrawn from thence. In Malam’s condenser the top can be removed, and after it is so, the cast-iron plate which rests upon the upright ones can be withdrawn also: so that the operator has it in his power, by drawing an instrument made for the purpose between the plates, (for the passage of the gas) to clear them out, and to open the holes through which the con- densations descend into the lower chamber. It would appear that Malam, in the construction of his latter vessel, as well as the former, had considered, when gas passes through circular pipes, that which is near the centre would be little, if at all, acted upon by the cold medium surrounding them ; and he has therefore compensated for that defect by causing the gas to present itself in such thin sheets as cannot fail to be affected by the coldness of the adjoining surfaces; thus giving a greater probability to the condensation being well performed. The present form of the hydraulic, in its most improved state, is that of a semicircular pipe, having covers or doors that can be removed at pleasure, and to which the pipes from the retorts are connected. This main contains a quantity of tar, into which the pipes from the retorts immerse a few inches. The tar thereby acts as a valve to prevent the return of gas into the retorts while in the act of charging. Formerly, the main con- sisted of a square chest for each retort, placed below, which received the dip-pipes in the same manner as the others, with pipes communicating between each chest; but from its near situation to the retort, the tar being continually impregnated with hot gas, hardened into pitch, and choked up the passage. From the difficulty of removing these obstructions, and the dan- ger attending them, this sort of hydraulic main has been given up, and the form referred to substituted in its stead. From these difficulties, and other considerations of conveni- ence, the hydraulic main in the several works in England, as well as in the works here, is now elevated a few feet above the range of the retorts, so that the gas, instead of a downward direction which it formerly took, ascends into this as a reservoir, by means of which the tar, in a state of vapour, is longer detained in the retort; and, in a considerable degree, (compared to what took place formerly,) is decomposed into gas. In the alteration of the construction of the works here of late, as well as in those lately fitted up by me at Kilmarnock, we have not only taken advantage of this vertical elevation of the hydraulic, but have also, by the peculiar construction of the roof, set off the hydraulic at eight or ten feet distance from the retort, in a horizontal direction, by means of which its con- nexion with the retort is at a distance of about sixteen feet; the union pipes forming in one line a vertical direction, and in the other a line inclining upwards to the hydraulic, into which they dip. By this lengthened elevated line, the tar in a consi- derable degree deposits itself, and returns to the retort to be decomposed anew. This mode of arrangement in the fitting up of the hydraulic has also the advantage of a free circulation of the surrounding air, by which means it forms in some degree a refrigeratory for cooling the gas, and thereby depositing several heterogeneous particles of tar and ammonia that were still held in a state of vapour. It has also the convenience of being easily got at to remove any obstruction that may generate in this part of the apparatus. - - Apparatus for shewing the exact Quantity of Tar and Ammo- niacal Liquor produced from a given Quantity of Coal.--To obtain a correct account of these products, Peckston constructed a table for shewing the exact number of ale gallons contained in the tar-cistern at every inch dip ; the application of which shall be shewn after describing the apparatus attached to the cistern. Considering that the specific gravities of tar and ammoniacal liquor were different, and that a body which would sink in the latter would swim upon the surface of the former, he proposed that two floats should be made, and attached to rods for shewing the respective heights to which each product rose in the cistern. In the annexed figure, A B C D, is a sec- tion of the tar-cistern. a b, surface of the tar. c d, surface of the ammoniacal liquor. E, a float of sound dry oak, twelve inches square, and a small rod of round three inches thick, - iron with a light index (the specific gravity 4. at the top for pointing of which being greater than that of ammo- + niacal liquor, will dis- place its bulk of that . . liquor and rest upon the surface of the tar.) º to which is fixed (G) out the height of the tar in the cistern IA against the graduated rod I. F., a float of cork swimming on the surface of the ammo- : Hº-fºur niacal liquor, fitted sº | 3 ||3: i §§ : º N zºº - # e. º § # *=l * % º B &º O tº: w 2%.J. zazazarº º 2 ºf C º S : i Sº #: ; H. : | º | º [. N º | & N i |G: al ||||| ||||W Eji====E======= --- E. #= º:*::::= E; º # ===E #5) § Nº. º :=#E. §: º §§§ Af is - | * | H- l with a rod H, and an index for shewing on the graduated rod K the number of feet and inches the surface of that fluid is dis-, tant from the bottom of the cistern. The difference between. G. A. S G. A. S. 371. DICTIONARY OF MECHANICAL SCIENCE. g the heights, as pointed out by the indexes on the graduated rods I and K, is the feet and inches of ammoniacal liquor in the vessel. e and f are two raised openings on the upper plate of the vessel, of about five or six inches in height, through which the rods G and H slide up and down. By this con- trivance they are steadied and always kept in a vertical posi- tion. This description of apparatus will answer for any tar- cistern; but as that vessel may be of different dimensions in different establishments, the table for use must be calculated accordingly. - Application of the Table.—Example. The index of the rod G. pointing to two feet six inches on the graduated rod I; required the number of gallons of tar answering thereto Look for two feet in the side column, and run your eye along the line till you come under six inches in the top one; you will there find 3,080 the number of gallons sought. To find the Gallons of Ammoniacal Liquor.—Subtract the height pointed out by the rod G from that shewn by the rod H, and with the remainder enter the table as above directed ; and you will find what number of gallons of ammoniacal liquor are ... in the cistern. Example. The rod G stands at two feet six inches, the rod H at four feet; what number of gallons of ammoniacal liquor Ft. In. Ft. In. Ft. In. are there in the cistern ? 4 : 0–2 : 6 = 1 : 6, opposite to which, in the table, find 1,848, and such is the number of gal- lons of ammoniacal liquor in the cistern. Purifying Vessels, and the best Mode of Purifying Coal-Gas- lduring the process of decomposing coals in close vessels, it is found, that, on their being heated to a certain degree, a part of the carbon of which they are formed unites with part of the oxygen, and produces carbonic acid; this, by means of caloric, is formed into carbonic acid gas. Whilst this process is going on, a part of the hydrogen of the coal is combined with another portion of carbon and caloric, which forms carburetted hydrogen gas. Olefiant gas, carbonic oxide, hydrogen and sulphuretted hydrogen, are also produced. According as the component parts of the coal submitted to distillation varies, so will the quantities of these products vary also, When the gas produced from coal is burnt without being purified, (that is, deprived of the sulphuretted hydrogen and carbonic acid gas which it contains,) or if it be not properly purified, it throws out sparks and produces a sulphureous acid, owing to the oxygen of the air uniting with the sulphur burnt with the gas. Such gas sends forth a suffocating odour, that is not only highly offensive, but injurious to health. Its levity carries it to the upper most part of the room where it is burnt, and there it is easily perceived. It tarnishes all metallic substances, and discolours paintings wherever metallic oxides may have been used in their execution. The general way of freeing it from sulphuretted hydrogen and carbonic acid, and rendering it fit for use, hitherto adopted, has been by passing it through a solution of lime and water of the consistence of cream. It may also be purified by passing it through very dilute solutions of subacetate of lead, green sulphate of iron, or hyperoxymuriate of lime. For the purifi- cation of coal-gas, when it is manufactured in the large way, various methods have been adopted. The following are those most noticed :-1st, By passing it through lime in solution; 2d, By allowing it to be acted upon by lime in a semi-fluid state; 3d, By passing it through dry lime; and, 4th, By pass- ing it through red-hot tubes into which are introduced clip- pings of iron. - . The best arrangement for these vessels which has fallen under my notice, as well as the construction of the purifier itself, was effected by Mr. Malam, of the Westminster gas works. A B C D, fig. 1, (see the Plate,) is a vertical section of the treble purifier, placed upon a foundation of brick-work; and fig. 2 of the same Plate, is a plan thereof. E E, F F, G G, fig. 1, are sections of the three interior chambers, bolted to the tops of their respective vessels by the flanches expressed in the Plate. It will be observed, that the bottoms of these ves- sels branch out with a kind of flanch, by which means the gas is acted upon by a greater proportion of the purifying mixture than if the vertical sides of it fell in a perpendicular line. HH is the axis on which the agitator II is fixed." KKK are three cylindrical vessels for the purpose of charging the respective vessels into which the purifying mixture is introduced by the bends L. L. L. M M M are the pipes which convey the gas into the interior chamber. N is the pipe which conveys the puri fied gas to the reservoir after it has passed through the series of vessels. O—the feed-pipe for bringing the purifying mix- ture from the vessel where it is prepared into the purifying apparatus. PPP exhibit the openings near the bottoms of the cylindrical vessels KKK, for emptying the respective ves- sels, which is effected by the slide-cocks Q Q Q. In the figure, the height to which the purifying mixture rises, is shewn in the two lower vessels; but the upper one is not charged. The: agitators are drawn by hand in the same way as has been already described when speaking of the single purifiers. When this purifier is first brought into action, the purifying mixture is turned into the uppermost vessel K, from whence it enters. into the uppermost purifier by the bend L, till it rises to the height of the uppermost edge of the vessel K. When such is the case, by opening the uppermost of the slide-cocks Q, that charge is emptied from the first into the second vessel, which being done, the uppermost purifier is again charged. The middle cock Q is then opened, which allows the charge in the second purifier to enter into the lowermost one, and whilst this is performing, that in the uppermost one is emptied into the second. The mixture is at the same time entering into the uppermost one, which is known to be properly charged, when the mixture rises to the top of its supplying vessel K. This being performed, the gas in its crude state is allowed to enter into the interior chamber of the lowermost purifying vessel by. the pipe M, which being filled, it blows underneath the flanch part of it into the outer part of that vessel which is unoccupied by the purifying mixture: from thence, by the next pipe M, it is conveyed into the interior chamber of the middle purifier, where the action is the same as in the lower one ; and thence, by the uppermost pipe M, it is conveyed into the highest wes- sel, where having again undergone the purifying process, it is allowed to enter the gas-holder by the pipe N. . On examining the Plate, it must appear obvious that the gas enters into the lowermost purifier in its most crude state; where, having been acted upon, it rises into the second in a purer state, and from thence into the top one. Under such circumstances, it follows, that the charge in the lowermost vessel is rendered useless first: on its being so, it is turned off by opening the bottom cock Q ; whilst this is performing, the gas generated has to pass through two vessels before it can enter into the gas-holder: but, in the single purifier during the time of charging, the gas passes into the gas-holder in an im- pure state, thus, by mixture with the pure gas, deteriorating its quality. The bottom purifier being emptied, the mixture in the second is turned into it, and that of the top into the second, when the top one is recharged. The lowermost vessel then always contains the mixture which has been most acted upon by the gas. By the vessels being placed in this way, a con- siderable saving in the expense of erecting them is effected : for, the top of the lowermost vessel answers as a bottom to the second, whilst the top of the middle vessel is the bottom of the upper one. The saving is not there alone; for, if the vessels were placed separately, they would require to be fitted with a number of valves and connexions, under this arrangement altogether unnecessary. Where the manufacturer has plenty of room on his premises for erecting a series of single purifying vessels, the extra expenses arising from the adoption of such plan not only con- sists in the first cost, but afterwards also, by requiring a man to work the agitators of each vessel; consequently, when three vessels were used, three men would be required for the pur- pose, whilst in Malam’s purifier one man with ease works the three sets of agitators. His arrangement possesses another capital advantage, for in most large towns where coal-gas manufactories are established, it is of considerable importance to save room, and nothing can be better adapted for doing so than his triple purifier. A mode of purification, differing in principle and practice from that we have mentioned, is by causing the crude gas to pass through retorts of a particular description, worked at a red heat just visible by day-light. Mr. G. H. Palmer obtained 372. G A S G A S DICTIONARY OF MECHANICAL SCIICN CE. a patent for this invention. Fig. 3, in the Plate, represents a longitudinal section of Palmer's purifier, and fig. 4, a front view of the same, with the mouths of the upper purifier closed, and the lower one open. This purifier is constructed of cast- iron, and it is set in brick-work under such an arrangement as admits of its being heated to the temperature required. In the Plate just referred to there are two purifiers heated by one fire. In no establishment can the process be carried on with a less number; in large works it would not only require the magni- tude of the purifier to be increased, but it would also be requi- site to employ a greater number of purifiers also. The purifiers are of an elliptical shape, and each one is divided into two equal parts by a vertical partition, which runs along its centre from the mouth-piece to within a few inches of its end. The mouth-piece is double, that is, it admits of two lids being applied to it, one of which is to the right of the partition we have just spoken of, and the other to the left. The lids of these mouth-pieces are secured in the ordinary way by means of luting and cross-pieces. As it is intended that but one of these purifiers should be brought into action at one time, the apparatus is provided with the double mercurial valve A, fig. 5, the rod of which being attached to one end of a chain, (run- ning over a pulley,) at the other end sustaining a counter- balance weight, the gas is allowed to enter into the upper or lower purifier as occasion may require; the valve being so contrived, that when the crude gas is admitted through it into one purifier, it is effectually excluded from the other. It is of considerable importance to the purification of gas by this mode, as well as every other, that it should have effectually under- gone the process of condensation, and as the admission of any of the condensible products into the purifier will materially tend to clog it up and to prevent the play of affinities required in this mode of purification, the patentee advises that the pipes conducting the gas from the condenser should rise towards the purifying apparatus. In fig. 5, the entrance and exit pipes are exhibited : the latter dip into a square box containing water, into which they are immersed so as to form an hydraulic joint between the purifying apparatus and the gas-holder. This box is furnished with a pipe for conveying off any products which may be condensed after the gas has passed the purifier, and it will of course require another vessel for receiving them, which must be constructed on a plan somewhat similar to the tar- cistern, but on a smaller scale. When this purifying apparatus is to be brought into action, it is to be at such a temperature as we have already stated, not that it is essential towards effecting the purification of the gas, but tending to the preservation of the vessel. This being effected, each compartment thereof is to be half or three- fourths filled with fragments or refuse clippings of sheet-iron, with tinned iron plates, argillaceous iron ore, iron-stone, &c. &c. It is to be noted, that whatever material may be used in this purifying vessel, such must be arranged in it so as to lie loosely together, in order that the gas may act upon as much of its area as possible, and that the sulphuretted hydrogen and car- bonic acid gas may be thereby arrested. Should the black oxide of iron be used in the purifier, which appears to be pre- ferred by Mr. Palmer, the operator should be careful as to the manner in which he disposes of it: always recollecting that a sufficient space should be left at the end of the purifier to allow the gas to pass round the divisional partition. The purifier being charged with any of the materials as above specified, the lids are to be secured and the valve opened towards the one so charged by raising or lowering the counter-balance weight of the valve, according as the upper or lower purifier may be brought into action. The gas then enters into that compartment of it which is to the left, and passing over the iron, or whatever else may be introduced round the divisional plate, is allowed to pass from the purifier by means of the pipe which is connected to the mouth-piece, which is to the right, into the hydraulic box, and thence by the pipe B to the gas-holder, to be stored up for use as occasion may require. - It is requisite that tests should occasionally be taken, in order that it may be known when the fragments of iron, &c. become inadequate for the purpose of purification. When they are so, the other purifier is to be charged in a similar way, the mouth-piece secured, and the valve opened into it, which, as we have before observed, will shut off the communi- cation to that which had been in action. When this is done, let the lids of the purifier which is out of use be removed, so as to admit the atmospheric air into it, the action of which will, prior to the purifier in action being rendered inadequate to perform its office, so far restore the materials to their proper tone, by reducing the sulphuret of iron again to a metallic state, as to allow the change of purifier to be again effected, and the process to be carried on to advantage. The operator is invariably to follow the mode pointed out, by using his purifiers alternately, till it is ascertained that the iron, or whatever substance may have been introduced, will no longer retain the sulphuretted hydrogen, &c. When such is the case, the contents of the purifier must be removed, and replaced by fresh material, and the process proceeded upon again, in the manner we have already described. When lime in solution is used for the purification of gas obtained from most of the species of Wallsend coals, a bushel and a half (Winchester measure) or 3225,63 cubic inches of un- slacked lime is found sufficient for purifying 10,000 cubic feet; its value, at fourteen shillings the hundred, being about eight- pence. In the same proportion must the purifier be charged for either greater or lesser quantities of gas generated. How- ever, as the qualities of coals vary considerably, perhaps no specific quantity can be put down as a general rule. The operator will very soon ascertain the fact, for his tests will prove whether the gas be pure, and he will charge his vessel. accordingly. - * TABLE, shewing the Comparison between the Lime Hundred and |Winchester Bushel, &c. to 21,696, or 21; Winchester bushels of 2150,42 º cubic inches each. to 27 cubic feet. equal to 46656 cubic inches. Most kinds of quick lime double their bulk by slacking. Many alterations have, at different times, been made in the structure of lime vessels for purifying coal gas; and, until lately, it does not appear that any form was hit upon suffi- ciently powerful to separate entirely the sulphuretted hydro- gen. This is now effected. The gas at present made in the Glasgow gas works seems to be entirely free of it, and will not tinge either silver or gilding; nor can the acetate of lead, a delicate test, discover in it any of this offensive mixture. On the Gas-holder (Gasometer); its Construction, and Descrip- tions of such as would best answer the Purpose of the Manufac- turer.—The gas-holder (or, as it is more commonly, though improperly, called the gasometer,) is that vessel in which the purified gas is stored up for use. It has been of various sizes and shapes: that most generally adopted in large works is from 15,000 to 20,000 cubic feet in capacity. It is a cylinder; the diameter being from thirty-three to forty feet, and the height from eighteen to twenty-three feet. - When speaking of the gas-holder, we are to consider it as composed of two distinct parts; that is to say, a capacious inner vessel, in large works generally made of sheet-iron, which is closed at the top and open at the bottom ; and a cast- iron tank or wooden vat of about a foot or eighteen inches greater diameter for containing water, into which the gas- holder sinks as it is emptied of gas, and out of which its lower edge, when full, cannot rise. By this contrivance the gas is prevented from escaping. The gas-holder is suspended by a chain over two grooved -wheels, fixed on a cast-iron frame placed over it; one end of which chain is made fast to an eye-bolt at the centre of the top of the gas-holder, and to the other is attached a frame sup- porting weights nearly equal to the weight of the gas-holder. It is to be observed, that by putting more weights upon the balance support, or frame, the gas-holder works at a less pressure, and, consequently, does not force the gas into the street mains with such velocity as when the weight is there decreased ; for if the balance-weight, and weight of the gas- holder, were very nearly equal, there would be little or no impetus for discharging the gas: it would, in consequence, escape with such languor at the orifices of the burners as to G A S G A s DECTIONARY OF MECHANICAL scIENCE. 373 afford but a very feeble light. To obtain a good light, the gas-holder should never be worked at less than about two inches' pressure; or, in other words, the surface of the water inside the gas-holder should be about two inches below the surface of the water contained between the outside of the gas- holder and the tank, or vat, in which it is suspended. For ascertaining the pressure at which the gas-holder works, a small pressure-gauge may be attached to the top of it, and secured from accident by a wrought-iron case. When, from the gas being turned into the gas-holder, it has risen but a few feet out of the water, the operator, by inspecting the graduated scale on the pressure-gauge, can see what pressure the gas- holder is then working at ; and, by diminishing or increasing the counterpoise, or balance-weight, regulate the pressure to 'what may be desired. One of the uses of the gas-holder is to regulate the emission of the gas towards the burners, which could not be effected without such contrivance. - We are now to describe the cylindrical gas-holder. In the Plate, fig. 1, is a vertical section thereof, and of the tank, &c. As the construction has been spoken of, I have here only to notice the particular parts as exhibited. A B C D is a section of the gas-holder, EFG H a section of the tank, II cast-iron flanch-pipes jointed together in the usual way, as columns for supporting the frame K.K. Upon this frame are placed car- riages for bearing the grooved wheels L. L., over which runs the chain suspending the gas-holder and balance-weight M. N is the pipe bringing the gas into the gas-holder, after it passes from the purifying apparatus. O, another pipe similar to the former, by which the gas is discharged into the mains when wanted for use. It need hardly be remarked, that these pipes must rise a few inches above the level of the water in the tank, to prevent a possibility of water getting into them. Upon the horizontal parts of the pipes N and O are placed valves for shutting off the respective communications when the vessel is full, or when it may be desired not to work into it. The figure represents the gas-holder as if it were about half filled. Fig. 2 represents the plan of the gas-holder just described. This is the most simple construction of gas-holders for working on the ordinary principle that has hitherto been adopted. Malam, to obviate the necessity of having all this heavy framework, proposed to erect gas-holders working with the specific gravity apparatus without it; and to shew the possi- bility of doing away therewith, in the spring of 1817 he con- structed a model. If we consider the tank and gas-holder to be such as have been just described, the following description will explain his principle. In the centre of the tank he pro- posed to form a cylinder of about four or five feet diameter, of cast-iron flanch plates, with the flanches inwards, so as to pre- sent an eveh surface outside. This cylinder was to be made tight to somewhat above the height of the tank : it was then to be carried by open castings to above the height that the top of the gas-holder might rise. The top of it was cast with a strong broad flanch, strengthened by vertical flanches underneath it, L thereon were bolted carriages for supporting two small wheels in a right line with each other, and with the centre of the cylinder. Over these wheels run two light chains, by which the gas-holder and balance-weights were suspended. It will be clear, that under such arrangement, as the gas-holder rose out of the water, the balance-weights would descend in the £ylinder I have been describing; and as it would be sufficiently capacious for them to pass up and down in, they would be quite out of the way, which in many cases is a desideratum. The expense of the cylinder would be considerably less than the most common frame could be put up for, and it would answer instead of steadying columns, without which gas-holders working vertically are very liable to swing towards one side of the tank, and falling out of a vertical position, to hang, or to work very unpleasantly. - - - - In a tank of thirty-five feet diameter and eighteen feet deep, the gas-holder will hold about 15,400 cubic feet of gas, when constructed with the framework, &c. in the usual way. By Mr. Malam’s arrangement, should the gas-holder be made of the same diameter, having a cylinder of five feet diameter for the balance-weights to work in, it will still contain 15,000 cubic feet, so that its capacity is not thereby considerably-lessened. By it, the first cost of erecting a gas-holder of 15,000 cubic feet capacity, will be decreased £200, or £250. It will, of course, require that the gas-holder should, in this case, be made so as to exhibit in the plan two concentric circles; one of which would be the diameter of the gas-holder, and form its sides,— the other, or interior, that which clipped round the cylinder, and of so much greater diameter as would allow it to slide up and down upon it freely. It would be riveted to the top of the gas-holder in the same way as the outer one, and made firm by one piece of angle iron going round its top, and another round the bottom. - But this gentleman, on pursuing his inquiries still further, . proposed to work the gas-holder without using chains or balance-weights; yet in such a way as to have the pressure uniform at all its heights; and to exemplify the possibility of the thing being effected, he constructed models of different dimensions. . By describing the following figure, which is a Vertical section of this gas-holder, the reader will understand the principles on which it is constructed so clearly as to render it quite familiar. The tank for this gas-holder is in all respects i& º º º: º º Sº SES - i FE§ É 5- º: º ſ s itº* º* º RE sº g º --- gº º - * sº-sº § §l ºscºsº. sº ſº ºf jº # º # : : | * § t # } * Zºº +}rn ſºft H ; * * * * * * * *e see #. # ~~~~~~ * ~ * * * ~ *- H C * É. ; #F#E º ji=#E. ſº - # #E}|#E; | Eºſ ſ F; - #Eß. #=; F; - #######| ||##| #PH#=#|É: |Hºff=#|H| #Eff # #F# El #Eff!}=#|{=# #|| | # Fſ ºlº # *E}; fe; H; % #E: &ſº I A : #Es § tº º G º similar to that used for others which work vertically. It is filled with water to the height expressed by the dotted liné B B. C is the pipe which brings the gas into the gas-holder, and D the pipe of exit therefrom. The gas-holder EFG H, when of 15,000 cubic feet capacity, is constructed of No. 16 wire-gauge plate iron. It is concave-shaped at the top, in order that if it should be erected in the open air, no lodgment of water, &c. may remain upon it so as to inerease the pres- sure. From the centre of the bottom of the tank rises a cast- iron column I, I, of about thirty-five feet in height; this acts as a guide for keeping the gas-holder in a vertical position, which is effected either by a pipe, (whose inner diameter is about half an inch more than the outer diameter of the column,) bolted to the top of that vessel inside, and braced to the upper edge thereof by a sufficient number of rods as KK, or other- wise by a tube of plate-iron of the same dimensions secured in a similar manner. At the centre of the bottom of the gas- holder is placed an air-vessel a b c d, constructed of plate-iron, the top of which is to be situated at such a height as to be level with the surface of water in the tank when the gas-holder is at its greatest rise. This air-vessel is to be of the capacity of such a bulk of water as is equal in weight to the actual weight of the gas-holder, less the pressure it may be intended to be worked at. For finding the dimensions of air vessels, for gas- holders of any capacity, is subjoined the following . . . . Rule.—Given the diameter of the gas holder, its depth, and weight, together with the pressure at which it is intended to be 5 C 374 G. A. S G. A. S DICTIONARY OF MECHANICAL SCIENCE. worked, also the depth proposed for the air-vessel, to find its diameter:— : . First:—Find the area of the base by squaring its diameter in inches, and multiplying that square by the area of unity ,7854. If the gas-holder work at one inch pressure, the area so found will be the number of cubic inches of water displaced, consequently, multiplying it by the number of inches of pres- sure which it may be worked at, will give the number of cubic inches of water displaced at that pressure. Divide the inches so found by 1728, which will reduce them into cubic feet. These multiplied by 1000 ounces, the weight of a cubic foot of water, gives the weight in ounces, which may be reduced into toas, &c. in the usual manner. Subtract this weight from the weight of the gas-holder, and the remainder shews the weight of such a bulk of water as is equal in weight to the absolute weight of the gas-holder, less the pressure it is to be worked at. Reduce the weight last found into ounces, and divide by 1000, the quotient shews the capacity of the air-vessel in cubic feet. Divide the capacity of the air-vessel just found by its depth in feet, the quotient will be the area of its base in square feet. Now as the air-vessel is cylindrical; to find its diameter, say As 355 : 452 : : so is the area to the square of the diameter. The square root of the last result is the diameter required. Example.—Given the diameter of the gas-holder 33 feet, its depth 17 feet, and weight 3 tons 15 cwt.—It is to be worked at inch-and-half pressure, the depth of the air-vessel being one foot, to find the diameter of that vessel :— First 33 feet – 396 inches. Then 396 × 396 x ,7854 – 123163,2864 superficial inches, the area of a circle whose diameter is 33 feet in inches. 123163,2864 × 13 = 184744 (nearly) cubic inches of water - displaced at 1% inch pressure. 184744 -- 1728 = 107 cubic feet of water nearly ; 107 cubic feet of water is equal to 107000 ounces, or to tons 2, 19, 2, 13. Then tons 3, 15, 0, 0.—Tons 2, 19, 2, 13 = Cwt. 15, 1, 15, or 27568 ounces. 27568-i- 1000 = 27,568 cubic feet, the capacity of the air-vessel. 27,568 -- 1 = 27,568, the area of the base of the air-vessel in - - square feet. To find the diameter, say As 355 : 452 : : 27,568. : 35,1, the square of the diameter. * V 35, 1 = 6,92 nearly,– therefore, for a gas-holder of the dimensions and weight as above given, and working at inch-and-half pressure, it would require an air-vessel one foot deep and five feet eleven inches in diameter. - . A vessel of the size just described would be sufficient so to buoy up the gas-holder when full, as to allow it to stand at a certain pressure ; but as it descends into the water in the action of discharging its contents, its weight would decrease from the circumstances explained heretofore, when speaking of gas-holders working by weights and chains; therefore, unless the air confined in the vessel could in some way be disposed of, the pressure would be continually changing. . To obviate this difficulty, Malam proposes the following appendages to the gas-holder. A pipe L L, of eight inches diameter, equal in height to the height of the tank, enclosing within it another pipe of the same height of two inches diameter, marked M in the figure. From the pipe M there is a com- munication to the vessel N by means of the small bend-pipe e, which rises to nearly the top of that vessel. Through the top of the closed vessel N is brought the vertical pipe A, which descends nearly to its bottom, and rises to a height equal to that of the tank of the gas-holder. This pipe is of such a diameter as to make it equal in capacity to the water displaced by the gas-holder when quite down. In forming rules for calculating the capacity of the compen- sating pipe A, and the vessel N, we proceed as follows:– First, find the circumference of the gas-holder thus, as 7 : 22 : : the diameter to the circumference:—then multiply the circumference by the depth of the gas-holder, and that again by the weight of a square foot of the material of which it is to be formed, adding the necessary weight for rivets, and the weight of that part which will be immersed in water, will be known. To find its bulk, say - As the specific gravity of the material of which the gas-holder is composed - Is to the weight last found reduced into ounces, So is one cubic foot To its magnitude in cubic feet. This magnitude divided by the height of the pipe A, will give the area of its base. The diameter of which may be found by the rule already given for finding that of the air-vessel. Example.—Given the diameter of the gas-holder 33 feet, the depth to which it is immersed in water 17 feet, the weight of a square foot of the material of which it is formed (plate-iron) 2 lbs. 11 oz. ;—its specific gravity being 7645,-to find the diameter of the compensating pipe A, its height being 17 feet: First : as 7 : 22 : : 33 : 103,7 the circumference 103,7 × 17 = 1763 nearly. - Then 1763 × 2 lbs. 11 oz. – 4838 lbs., to which, if we add 762 lbs. as an allowance for rivets, &c. we have 5600 lbs. or 89600 ounces, for the weight of that part of the gas-holder which becomes immersed in water. To find its bulk, say As 7645 : 5600 : : 1 : 1 1,72 cubic feet nearly. 11,72 -i- 17 = ,69 (nearly) the area of the base of the pipe in question., For the diameter, - As 355 : 452 : ,69 :: ,8785 the square of the diameter * V,8785 – ,937, or 11+ inches nearly. Therefore the compensating pipe for such a gas-holder would require to be 11% inches in diameter. - As the vessel N is connected by the bend e to the upright pipe M, and that to the air-vessel by the pipe O, (which rises and falls with the gas-holder between the pipes L and M, the space being filled with water so as to form an hydraulic joint,) and the small pipe PP, which runs along the top of the gas- holder, and from its centre descends into the air-vessel, it will be evident that if this gas-holder be brought into action, it must be prepared for use in the following manner. We will sup- pose the gas-holder to be down in the tank, which is filled with water. The pipe L L is also filled with water to within a few inches of the top. Then into the vessel N let the water be poured by means of the upright pipe A till it runs out at the cock f, that cock being situated at such a height as will indi- cate, when, by pouring in more water, it would descend in the bend e. Things being thus prepared, attach the condensing apparatus to the cockf, which is fitted with a screw for receiv- ing it, and inject air till such time as the water from the vessel N rises to the same height in the pipe A as it is in the tank of the gas-holder. When such is the case, part of the vessel N, from the top to the dotted line g, will be filled with air, as will also the bend e, the pipes M and O, and the small pipe P. Whilst this is performing, it is evident that the air will be thrown into the air-vessel; for if we suppose the water to have risen to the same level in the pipe A, that it is in the tank, there must be the same pressure upon the air in the vessel N, as in the air-vessel a b c d, and the air will be equally condensed in each. But as the air-vessel will not then be filled with air, it must be considered under like circumstances with a vessel of any sort inverted into water. If a vessel be pushed or let down to any depth in that fluid, then by the pressure of the water some of it will ascend into the vessel, but not so high as the water without, and will compress the air into less space, accord- ing to the difference between the heights of the internal and external water. Should the tank be about thirty-four feet in depth, the air-vessel would, with such pressure, have the weight of two atmospheres upon it, and the air therein would be compressed into one half the space it would occupy when the gas-holder had risen to its greatest height, and the top of the air-vessel was level with the surface of water in the tank. This compression would, in a similar ratio, be increased or diminished with a greater or less depth. Considering these points, it follows that the capacity of the vessel N must be such as to contain a sufficiency of water for ſilling the pipe A between about two inches below the top of the bend e, and as much above the bottom of the pipe A, when the gas-holder is worked at inch-and-half. pressure. The cock f being shut, and the condensing apparatus removed, if gas be allowed to enter into the gas-holder, the vessel will be caused to rise in the G A S • A s 375 DictionARY OF MECHANICAL scIENCE. tank, and as it rises the column of water in the pipe A is depressed, and the air out of the vessel N passes into the air- vessel a b c d, thus increasing the buoyancy of the gas-holder in proportion to its rise, till it has attained its greatest height, and then all the air has been discharged from the vessel N into the air-vessel. This contrivance is well adapted for keeping up a regularity of pressure, and extremely simple in operation. There have not been wanting other contrivances for working gas-holders by means of air-vessels, as Mr. Perks’s, in which the air-vessel was closed, and attached to the interior of the lower edge of the gas-holder, and so constructed, that by the opening and shutting of valves to increase or diminish the pressure, by the admission of water, or by letting in of air. Another patent was obtained in 1819, by Mr. Outhett, of Lam- beth, for a gas-holder working with air-vessels. His plan differs from both the former. The vessel for giving buoyancy to the gas-holder, being constructed of strong materials, is closed, and the air in it condensed to a very considerable degree, whilst the other, which answers for the compensating apparatus, is open. Both these vessels are placed a little above the centre of gravity of the gas-holder. # In addition to the list of gas-holders is one of Clegg's inven- tion, with a very shallow tank, into which the lower edge is immersed. This gas-holder occupies a greater area of base than such as have already been mentioned. When it is full of gas, the end view is represented by an equilateral triangle, the bearings being from the angle opposite to the base. This gas- holder is so constructed, that the sides have a tendency to ºłose with each other, and therefore when the valve of supply is opened, such tendency expels the gas. In this gas-holder it is evident, that some part of each end must be constructed of flexible materials. It is known to the gas-light manufacturer by the term “Collapsing Gas-holder.” Various Kinds of Valves, Syphons, and Tar Wells.—The necessity of adopting effectual means for shutting off all com- munication between the gas-holder and street-mains, as well as from one ramification of main to another, suggested the propriety of introducing valves upon the line of main-pipes. Those originally used by the gas-light companies were slide valves, similar to what are used by the water campanies; but, such have now been long out of general use ; and hydraulie, or pneumatic, valves, or combinations of both, have supplied their place. The valve seems to have undergone ºf more changes in its structure than almost any other part of the gas- light apparatus; it appears to have been within the reach of most men, and, according to the abilities exerted, it has been altered. In some cases, change appears to have been the sole object in view, for alterations which did not lessen the expenses of construction, decrease the dimensions of the valve, or render it more effective, could not be termed improvements. It will not be necessary to take up time in describing all the various kinds of valves which have been, and are now used. We shall, deseribe but two, namely, an hydraulie and a pneu- matic valve; the former being well adapted for use in the manufactory, and the latter for the street-mains. The annexed figure , is a vertical section of an hydraulie valve, invented by Malam, which is particularly useful in the connexions about the purifying vessels, and on the works. This valve is cylin- drical, flanched at top and bot- tom, and cast with a flanch quarter bend projecting up- wards, from one side of the diameter required. At the bot- tom is bolted a double cup, which rises to the height of the lower part of the bend just mentioned. Through the cen- tre of this cup is an opening of | the same diameter with the bend. This centre part pro- jects a few inches below the bottom of the valve, and is fur- . nished with a flanch for joint- ing it to the pipe by which the - gas is brought into it. Through . . . * ºxx º º &sº &_cºs. Sº SS$ºSººse *sº sº 2.ſ.º. #Sºzzº * lºcalºº sº lºº §lºš lſ; Sºx - & fi º § N az Ǻ § f : *º 3. º º' tº º * § §§ º >Jºš Žižº's gº Sº º º º i i l § º % ~ # º ºt ſº Sº 2.º º f the bottom of the valve is brought a bend of wrought-iron tube, as expressed in the figure, which is connected to an upright pipe of the same material, rising to the top of the valve, for introducing water into the double cup. the top of this supply- ing pipe is covered with a cap, which is screwed on, save when it may be necessary to furnish a supply of water. The top of the valve is covered with a blank flanch, which is jointed and Secured thereto by screw-bolts in the usual way. At the cem- tre of the top is fixed a stuffing-box, the bottom of which is tapped for receiving the square thread lifting-screw. This screw is surrounded by a wrought-iron case with a thread inside for receiving it. . The case is moveable in the stuffing box, and of sufficient height to allow the lifting-screw to rise to the greatest height that may be required. It is furnished with two handles, which with it serve as a wrench for raising or lowering the screw. The bottom of this screw is secured to a double inverted cup, as shewn in the figure, and therefore that is lifted or lowered with it. The inverted cup is so construct- ed, as when let down to fall between the two circles forming the lower one ; and thus, if we suppose the bottom cup to be nearly filled with water, and the upper one immersed into it, it follows that the valve so constructed is capable of sustaining double the pressure of that which is constructed with but a single cup, and under such arrangment it will not occupy more than half the room of the former, to be equally effective." It may be worthy of remark, that the objections to the suffi- ciency of this valve have been most fully answered by the expe- rience of several years. The action and counter-action of the inner and outer of the lower cups being reciprocal between each other, as must appear evident on examining the figure, renders it altogether safe. Fig. 1. Fig. 1, is a plan of this valve, which, from what has been said, does not require fur- ther description. Fig. 2, is a vertical section of Malam's pheumatic valve, which from the stuffing-box at the top, to the step for the spindle at the bottom, is somewhat more than twice the diameter of the main on which it is to be used. Thus, for instance, from the top to the bottom inside of a fourteen-inch valve of this description, will be about three feet, and in a similiar proportion for smaller or larger ones. The body of the valve is Square, as shewn in the plan, a few inches from the top of which is at one side a socket, and in a direct line with that is placed at the other side a Spigot, in order that it may be introduced into the range of main-pipe as necessity requires. The inner faces É of the socket, as well as spigot, project about an inch inward, and require to be | chipped and filed so as to present perfectly plane sur- Fig. 2. * º tº 22% ſ£41% Fº º #zzº %zº §§ | Ş Sº ſº Nº. § §º SS SS sº ºtà: §§§§º * , faces. Through the top of † Wºº º º & §§ºft the valve, which is fitted ####### with a stuffing-box, is intro- § {# Tā #: #5 b. ; : iſºft duced the spindle, in such #º a way that the lower end of #1-#-ºji it rests in the step at the *S*s SSSSSS .*. ºf- bottom of the valve, and the boss beneath brass couplings, or a collar in the bottom of the stuffing-box. So that when the stuffing-box is fitted, and the glan bolted down, should the wrench or key be applied to the square top of the spindle, it will turn freely round, but without being raised. If we then suppose the valve to be open, as shewn in the figure, there will rest upon the bottom two wedge- shaped pieces with their points downwards, and between them the frustum of a square. The spindle passes through the latter, which is fitted with a screw for receiving it, and it is thereby raised or lowered, and the valve shut or opened. Upon the centre-piece, at a convenient distance from the top, is bolted a spring, which is also connected to the side-pieces, so as to act between the top of them and the fastening bolt. In its natural 373 G. A S G. A. S. pictionARY OF MECHANICAL SCIENCE. position it has a tendency towards drawing the side-pieces together, and of pushing the middle one downwards. This contrivance allows the three pieces to be lifted together, without being rubbed against the inside of the valve, till the outer pieces touch the top. The further ascent of the outer pieces being then arrested, the middle one eontinues to be raised by the screw till they are completely wedged up against the interior of the socket and spigot. And as these wedge- shaped pieces are faced with cork or leather, the pressure can be carried to such pitch as effects an air-tight joint upon each, thus effectually preventing the passage of the smallest portion of gas. When the valve is in such position, the spring will be elongated horizontally, and so remain till the screw is turned for lowering the interior pieces, when it again resumes its former shape, and thus draws the side-pieces towards each other, and pushes the middle one downwards. The annexed figure is a plan of this - - valve. It exhibits the flanch to which the top is bolted, the socket and spigot, shewn in the for- Iner section, and the top of the inner pieces with the facings of cork. That this is an effective and simple valve, appears evident from barely inspecting the figure. It is of small size, and can be got up at a very trifling expense, when compared with others more generally adopted. Syphons are of two kinds: the larger sort are distinguished by their diameters, two, three, or four inches, &c, syphons; the smaller, which are used on the service-pipes, are generally term- ed “gun-barrel syphons,” or “bottle syphons.” The shape of the vessel itself is similar in each case, but the furniture and use are different. The larger sized syphon is a cast-iron cylin- Ef CE º 5CE ECE E 5- £Că . E. rical vessel of about a foot deep, and of the diameter inside || agreeable to its distinguishing name. It is flanched round the top, and to this flanch is bolted a blank flanch. Through the centre of the blank flanch a hole is drilled and screwed for receiving a piece of wrought-iron tubing, which descends nearly to the bottom, and projects a few inches above the top. Another piece of similar tubing is bent and screwed also into the top; thence rising nearly perpendicular, it is connected to the bottom of the main-pipe, from thence the water of conden- densation descends by it into the syphon. * The gun-barrel syphon is, in shape, nearly similar to that just described, but its dimensions are much smaller; namely, about eight inches deep, and four in diameter. The tar-well, is a cylindrical vessel of about ten inches diameter inside, by twelve inches deep, when used upon all mains of less than ten inches diameter; but when it is used upon larger mains, the diameter of the body, of the tar-well Imust be about two inches greater than the diameter of such main. This vessel is cast with a socket at one side, and a spigot at the other, similar to those of the pipes with which it is to be used; therefore, a tar-well with a socket and a spigot, similar to a two-inch pipe, is called a two-inch tar-well, one for a three-inch pipe, a three-inch tar-well, and so on. Mains and Distributing Pipes.—In the present supplement to the Encyclopaedia Britannica, it is stated, that a pipe of an inch bore will supply 100 jets; but it ought to be observed, that this only holds in peculiar circumstances. If we suppose a pipe of the above dimensions extended for 300 yards from the point of supply, we shall find that the jets will gradually dimi- nish in intensity of light towards the extremity of such a pipe. It is, therefore, safer, even in point of economy, to calculate on the pipes being something above rather than below this state- ment, between the supply and quantity of light. A want of experience on this branch of the establishment, and an increased demand for gas beyond what was calculated upon, has frequently created great trouble as well as very serious loss, not only in the works here, but in several of those in England. Accordingly, in some cases they have been obliged to lift and relay pipes of additional bore, and in others to lay down additional subsidiary mains. This has at no time arisen from any deposition of crystals or other matter in the pipes, so as to contract the area, but from want of sufficient practice to shew what dimensions under different local circumstances would be needful, and from the increased demand alluded to. Should you, therefore, suppose that an increase of light, to the extent of 10,000 jets, would take place in a few years, it would then be prudent that the mains for the proposed esta- blishment should not be less than 19inches in diameter, and that the other distributing pipes in the various streets of the town be proportioned in the same ratio; and this must be obtained by a survey of the shops and other establishments where gas- lights may be supposed to be taken in. - - Valves and Water Traps.-The water valves which we should recommend as preferable to any other yet in use for shutting off the gas, must also be proportioned to the area of the pipes, where it shall be found needful to place them; and these, in ali cases where they are needful, will serve not only as stop valves, but as drips to carry off the condensed vapours that collect in the pipes in a liquid form. The number of these necessary must also be ascertained by actual survey, and from the inclination of the streets. - - Service and Inside Pipes.—The service pipes that branch off from the distributing ones, to convey the gas within such premises as are to be lighted, may be of cast-iron, varying from # to 1% inch bore, and upwards, as the quantity of light to be supplied may determine. The pipes that have hitherto been fitted up for shops and other manufactories, have for the most part been of wrought iron, which have been found to answer better than copper ones, which were at first in use ; but of late, block tin pipes have superseded in a coniderable degree the others. Pipes of this description have advantages which strongly recommend them to consumers, and to manufac- turers of gas. They are not acted upon by the gas so as to be corroded, nor does any matter adhere to their interior; consequently, any complaints or trouble that formerly occurred from these sources will be completely obviated. Burners.-Argand burners of three different sizes, and jets of different figures, are pretty generally in use. Each jet is equal to the intensity of light of a candle and half, weighing six in the pound, and will consume about one cubic foot of coal gas per hour. The No. 1 argand burner is equal in intensity of light to three of these jets, and will consume only about two cubic feet of gas per hour. The light derived from such a burner being much greater in proportion to the gas consumed, than in burners of the jet form, some would strongly recom- mend that argands as much as possible be used, as a matter of material interest to a gas company, and of comfort to the community. Some of the works in England, aware of this, give out none but argand burners to their customers, except in cases where they use meters. Apparatus for the Production of Gas for Illumination, from Oil, &c.—For the more general diffusion of the benefits arising from the use of gas-lights, where houses and manufactories are at a distance from towns, and where coals are scarce, and room scanty, Messrs. Taylor and Martineau, some years ago, in- vented and brought to great perfection, an apparatus whereby every purpose of economy is answered, and a most beautiful, and splendid light is obtained merely from the distillation of impure oils, grease, &c. A general idea of the process may be formed from the fol- lowing account:—A quantity of oil is placed in an air-tight vessel, in such a manner, that it may flow into retorts which, are kept at a moderate red-heat; and in such proportions, as may regulate the production of gas to a convenient rate, which may be easily governed by the will of the operator. The oil, in its passage through the retorts, is decomposed, and converted into gas proper for illumination, having the great advantages of being pure and free from sulphurous con- tamination, and of supporting a very brilliant flame, with the expenditure of very small quantities. It will, however, gene- rally be found that some oil passes off in the state of vapour, without being decomposed; and in order to condense this, and return it again into the oil vessel, the gas is made to pass through a vessel immersed in water, by which, and its exit by a worm, the vapour is condensed again into oil, and flows at once into the oil cistern, so as to come. again into use in the retorts. As a further precaution to purify the gas from oil, which may be suspended in it in the state of vapour, it is con- G A § G A S 377 DICTIONARY OF MECHANICAL SCIENCE. veyed into a wash vessel, where, by bubbling through water, it is further cooled and rendered fit for use; and passes by a proper pipe into a gasometer, from which it is suffered to branch off in pipes in the usual manner. An apparatus, fit for a large establishment, and capable of producing from 1,600 to 1,800 cubic feet of gas at one ope- ration, requires only the cleaning out the retorts, which be- comes necessary from time to time, from the accumulation of a certain quantity of carbonaceous matter. This, and the necessary attention to keep up a moderate fire, is the only trouble which attends the use of the apparatus; and the time required for the production of the above quantity, would in general be about six hours. The number of lights which would be supplied by 1,800 cubic feet of oil gas, reckoning that they were argand burners, and employed for four hours, would be about 300, and giving a light equal to from 3,000 to 3,600 mould candles. In order to adapt them to different establish- ments requiring smaller quantities of light, and to fit them for private houses, they may be made of various sizes, accommo- dated to different degrees of power, and suitable, by the small space they occupy, for situations where much room cannot be spared. One capable of furnishing gas for from 12 to 20 argand lights, may be conveniently placed in a small kitchen fire-place, and will occupy a space of four feet by three, and a height of about eight feet. - For private houses, a gasometer should not contain less than from 80 to 100 cubic feet, and for larger establishments, they should contain from 300 to 600. There are great advan- tages in having the gasometer as large as circumstances will admit; in the first place, the demand of the longest night in winter should be provided for, and the increased consumption occasioned by lighting the greatest number of rooms for Com- pany. In the second place, both the trouble and expense of the gas is diminished by having a reservoir sufficiently capa- cious to hold some days’ ordinary consumption, by which, as the gas improves by keeping, it is most convenient and econo- mical to have to make it but once or twice a week. In a private house, where three or four rooms are ade- quately lighted, and where a small flame is kept burning all night in a bed-chamber, it has been found that from 20 to 3G cubic feet of oil-gas is sufficient; and therefore, a gasometer containing 100 feet will give a supply for four nights. Such a gasometer will be about six feet long and four wide, and rather more than four feet high. One for 400 cubic feet may be ten feet long, and seven wide, and about six high. There is mo occasion that a gasometer should be placed near the other parts of the apparatus. GAS Light. nation of the illuminating powers of oil and coal-gas, having shewn the manner in which each is prepared and dispensed in cities. The Professor's experiments were made at the request of the Edinburgh gas light company, and are confined to two points: 1st, The comparative density of the gases: 2dly, Their relative powers of illuminating. “ 1st, The density of your coal-gas commonly does not much exceed six-tenths of that of atmospheric air: When I began the operations, its density was only 593; but it was afterwards 618, and is now 623. In winter I once found it to be '680, and at another time as high as 700, though it was oftener at 600. The variation seldom, I presume, exceeds the eighth part. A small quantity of oil-gas, procured for the experiments, I found to have the specific gravity of only 674, not greater indeed than that of your coal-gas, when made from the best coal. The oil-gas, however, furnished by Mr. Milne, manufactured on a small scale, and apparently with great care, at his works, was materially denser, being as high as '943, though on a former occasion I found it to be only 810. If we assume in round numbers the density of coal and oil gas to be six and nine-tenths of that of atmospheric air, it is easy to compute, that under the pressure of half an inch of Water, the quantities discharged from the burner No. 1. of the oil-gas, which contains ten holes, each having the 1-40th of an inch in diameter, would be respectively 44 and 3 8-9 cubic feet. The quantities actually consumed, however, are only about the halves of these measures, because the aperture is always con- * partly shutting the cock to bring the flame to the | serted.” - We will now give Professor Leslie’s exami- | same standard height. When the flame is thus regulated, I find the consumption of the same gas, and with the same burner, always the same, whatever may be the load placed on the gasometer. For instance, after increasing the load four times, and consequently doubling the velocity of discharge, yet on adjusting the cock so as to reduce the flame to its former height, the expenditure of the gas was not altered. “2dly, The illuminating powers of the two gases were mea- sured with great accuracy, by the application of my photome- ter, which I had somewhat modified to exclude every irregular influence of heat. The indications were steady and easily noted, nor could the judgment of the observer be liable, as in other cases, to any sort of bias or indecision. It hence appears to be ascertained, that with the same burner the powers of illumination of different gases, and of the same gas in different states, are very nearly proportional to their densities. The Same weight of gas of any kind gives out the same quantity of light; but if equal bulks be taken, the illuminating powers fol- low the ratio of their densities. But the quantity of light emitted is not uniformly proportional to the measure of the gas expended. A certain burner, for instance, was observed to produce double the illuminating effect, though it consumed only one-half more of either species of gas. With No. 1. of the oil-gas burner, the relative illumination of Mr. Milne's oil- gas to that of your coal-gas, was found to be as six to five. But a cubic foot of the former lasted thirty-eight minutes, while a cubic foot of the coal-gas was spent in thirty minutes and a half. The relative vo- lumes consumed were hence The Gas Burner. in the space of an hour 1-58 º and 1.97, or in the ratio of Aſ four to five. Wherefore while - five cubic feet of coal-gas give five degrees of light, four cubic feet of the best oil-gas give six degrees; that is, for equal vo- .: fºss ſº Jº Pº tººls: ºutſº Fºº is lumes the illuminating power Af § of the oil to the coal-gas is as # =s §: to two. tº: º COn- # # clusion was obtained on pass- Šs: == ing those several gases suc- cessively through the argand * ==- coal-gas burner No. 2. Thus S$== the illumination of oil-gas is actually less than the half of what has been currently as- The advantages of oil-gas are, that being free from sulphur- etted hydrogen, it will not injure metallic goods, pictures, elegant bindings of books, or gilded furniture of any descrip- tion; and will give out, when burning, only one half the heat of coal-gas. And the further advantages arising from the portable form in which it is now offered are—1st, That from being moveable, a less quantity of light will be required in an apartment than when the light is fixed in one place. 2dly, That it is capable of being economized, as a great or small number of the lamps may be lighted, and the strength of the flame diminished or increased at pleasure; the customer pay- ing for no more gas than is used. And, 3dly, That the gas may be used in situations where it is impossible in any other manner to convey gas lights. e iº Portable Gas Lamp.–The following figure exhibits a different plan for burning gas, contained in a portable vessel, with an equal flame. A, B, C, D, is the vessel, E the opening at which the gas is forced in, by means of a pump, and F is the jet at which it escapes and is consumed. "H, I, is a bar to support the gas tube K, S, L, open only at one end. The Space from K, to the float P, contains mercury. The two ſloats, P and R, are connected by the string or chain X, Y, and to the top of the float R the stout wire Z, Z, Z, is attached perpendicularly. To the top of this wire is affixed a cubical piece of metal, shaped on all sides like a wedge. This is contained in a kind of box marked 3, 3, 3, 3, which is also shaped wedge-like, but with a greater angle at the bottom; 4, 4, are two metal plates, each exactly the same size as one side of the box. These plates are to be pushed backwards or forwards by the screws 5 D 378 G. A. S. G. A S DICTIONARY OF MECHANICAL scIENCE, 5, 5, till the aperture is adjusted, when the ends of the screws may be cut off. Now, suppose the cubi- cal vessel A, B, C, D, empty of gas, the mercury in the tube is alike high at both surfaces. The forcing pump is applied at E.; and, as the gas is condensed, it compresses the air in the end of the tube at K: of . course the mercury rises, carrying the float P up along with it; the other ball is drawn down, and brings down with it the wire Z, which gradually stops the opening at the top of the wire; and, as the gas contained is diminished, the pressure will be taken off the surface of the mercury at R, the air at K will expand, and raise the wire Z, and enlarge the opening. - - - - The Portable Gas Company of London, have positively pledged themselves to the public, that every one of these lamps has been proved to resist a pressure of between 600 and 700 lbs. upon the cubic inch; and, that they will in no instance be subjected to a pressure of little more than 400; there will therefore be a surplus strength of 200 upon every square inch; or in other words, each vessel has sufficient power to receive a supply of gas nearly equal to fifteen additional atmospheres! The most timid need not then fear an explosion of these lamps. . . - Comparative Merits of Coal and Oil Gas.--A good deal of dis- cussion has of late arisen regarding the comparative merits of these two gases, and so much has the subject been perplexed by the conflicting statements of rival manufacturers and com- panies, that the question can hardly yet be considered as settled, although the general impression undoubtedly is, that the coal gas, where coal is abundant, has the advantage in point of economy, though it is rather inferior to the oil in point of purity. . As the subject has become interesting to the public, we shall state a few facts regarding it, which are, perhaps, not generally known, and for which we are partly indebted to an interesting report lately published by the Dundee Gas Com- pany, and which forms the result of certain inquiries set on foot by that Company for their information. First, then, in regard to the expense of manufacturing coal gas, this, as may be expected, will vary with the price and quality of the coal, and also with the skill and economy in managing the different processes of the manufacture. In Glasgow, the cost of manu- facturing 1000 cubic feet of coal gas is so low as 4s. 9d, exclu- sive of interest on capital. In Edinburgh it is from 7s. to 8s. In Liverpool and London about 10s. But the selling price of the gas in these different places is exactly in proportion to the * The Whitechapel Road Oil Gas Company, according to Mr. Tait's information in the Dundee Report, divided, at the end of the first year, 2} per cent. ; but at the last general meeting (November, 1823,) no dividend was made. The Hull Company, by the same report, has paid nothing; the Norwich nothing, and the Colchester has been converted into a coal gas. # Although the exact proportion of the illuminating powers of these gases has not yet been settled, a good many experiments have been made with this view ; these, when rightly considered, do not differ from each other so much as has been supposed, and agree, on the whole, pretty nearly in assigning the above ratio of between two and four to one in favour of oil, according to the quality of the coal gas. The subject has not certainly been examined with sufficient attention, nor with any thing like that degree of accuracy which such experiments demand, and in the present state of science, easily admit of, and we are surprised that some of the parties interested have not already set on foot such inquiries as will set this matter completely at rest. Professor Leslie, we understand, has been recently engaged in making some experiments on these gases; and certainly no instrument is so well adapted for comparing their illuminating powers as the photometer, with which he has contrived to measure the various shades of light. Under the hands of skilful observers, this instrument could not fail to lead to interesting results. The method of shadows, however, is not entirely so satisfactory, nor in many respects so convenient, because we cannot easily compare, in this manner, the gases of different places unless they are actually brought together, and huraed in the same apartment, whereas the photometer measures the actual as well as the relative degrees of light. Still, however, the method of shadows, with attention, and in the same place, will give a pretty near it is generated. given rise. : price of producing it. In Glasgow, 1000 feet of gas sells at 8s. 6d., in Edinburgh, at 12s., in Liverpool at 13s. 9d., and in London at 14s. 6d. or 15s. The difference arises partly from differences in the dividends paid by the companies on their respective capitals, and partly, also, we believe, from waste, and perhaps part of the current expenses not being included in the cost price. - - - But even the quality of the gas in different establishments varies considerably in its illuminating power, owing partly to management, but chiefly to the nature of the coal from which In this respect the gas from cannel coal, from which most of it is got in Scotland, is decidedly superior to the London gas, which is all produced from Newcastle coal; a cubic foot of the former will burn from one to one and a half. times longer than one of the latter, and give all the time the same degree of light. On this account, therefore, the fair illu- minating value of the gas in the above places, does not cor- respond with its selling price, the London gas being really from one to one and a half times dearer. This consideration is of essential importance in all our inquiries into the economy of gases, and a want of due attention to it is one of the chief causes of those discrepant results which have been obtained on this subject, and of that diversity of opinion to which they have In regard now to the price of manufacturing and selling oil gas; this is pretty much the same in different places, and the gas being all generated from the same material, its quality is hence pretty uniform. The cost of manufacturing 1000 cubic feet of oil gas is estimated by Taylor and Martineau, the patentees, at 26s.; by Mr. Peckstone at 28s. ; by Mr. Ricardo, of the Bow Works, at 27s. ; and it is actually made at Hull for 28s. ; and at Leith, we believe, much the same. The selling price again is in London 50s. ; in Hull 50s. ; in Leith 50s., until of late it has been reduced to 40s., the lowest price at which it has ever been sold. But there is one important circumstance to be noticed here. At the above prices of the coal gas, all the Companies have been dividing considerable profits, which may be averaged at 8 per cent. on the capital of each, while the Oil Gas Companies again, at their prices, have been in many cases losing, and in no case dividing more than 2% or 3 per cent.” It thus appears, then, that the same quantity of gas which, in the case of coal, sells in Glasgow at 8s. 6d., in Edin- burgh at 12s., and in London at 14s. 6d., cannot, in the case of oil, be any where sold with a profit under, we may safely say, 45s., supposing even the oil to continue at the same rate to which it has fallen of late years. . • . But the quality of the oil gas is much superior to that even of the best coal in its light-giving power. A cubic foot of it will burn with an equal degree of light between three and four times longer than the London gas, and between two and three fimes longer than the Scotch gas.t. If we take this circum- cannel coal and other Scotch coals. approximation to the truth; and we shall just state the results obtained in this manner by different observers. In London, Messrs. Taylor and Mar- tineau find the illuminating powers of their oil gas 3} times superior to that of the coal gas in the neighbourhood. This estimate has been confirmed by Mr. Brande, and several other observers, more particularly by Mr. Dewey of New York, in an experiment conducted with great fairness, each foot of the oil gas burning exactly three and a half times longer than a foot of the coal. Hence, it has been laid down at once as a general rule, that oil gas is three or four times superior to coal in illuminating powers; and this notion, sanctioned by the names of the observers and the accuracy of the experi- ments, and propagated with zeal by the oil gas advocates and companies, has had considerable weight with the public; the Committee of the Dundee Com- pany, for example, having hence calculated on the illuminating powers as 3 to 1. But we believe it is undeniable, that the London gas obtained from Newcastle coal is considerably inferior to the Scotch gas obtained from the The exact proportion we do not know, but it is between 1 and 1% times inferior—say, then, that it is only 1% times, and this, in the case of the Scotch gas, will reduce the estimate of Taylor and Martineau, the oil gas patentees themselves, to the proportion of 23 to 1 in favour of oil; and this corresponds pretty nearly with the observations which have actually been made in this country. Mr. Crichton of Glasgow, late civil engineer there, makes the proportion 2 to 1 in favour of oil. Dr. Ure of Glasgow, finds the same proportion; and Mr. Milne, one of the agents for the oil gas patentees, according to a writer in the Dundee Report, makes it, in reference to the Glasgow coal gas, as 2, or, at most 2% to 1. Experiments, we believe, have also been made by the Company here on the G. A. S G. A. S 379 DICTIONARY OF MECHANICAL SCIENCE. stance into account, then, we shall obtain an exact, estimate of the comparative economy of the two gases; 1000 feet of oil gas will thus give the same quantity of light as 3500 feet of London gas, and as 2500 feet of Scotch gas; and the prices of the same quantity of light derived, from these different gases respectively will be, from oil gas, 45s., London coal gas, 50s. 9d., Edinburgh coal gas, 30s., Glasgow coal gas, 21s. 3d. The expense of the same light for tallow candles, at 1s. per lb., is about 80s. Of all these places, then, London is the most likely for an oil gas work to succeed as a profitable concern, Edinburgh next, and Glasgow the least. It appears evident, however, from these facts, that even in Edinburgh we cannot expect to obtain our light from oil gas at a price less than 50 per cent. higher than from coal, even though the price of oil should continue as it is. Considering indeed the waste which takes place in converting oil into gas, together with the expense of the process, it cannot be expected that the latter should ever form a very cheap light. In the present state of the manufacture, a quantity of the inflammable matter of the oil is lost by the imperfect mature of the decomposition, besides a quantity of the gas itself, which is necessarily wasted in every gas establishment. Of the amount of these losses we are not informed, but a loss there certainly is to some extent. Moreover, were there no expense attending the manu- facture of oil gas, its light could not be so cheap as that from the oil itself, burned in a good lamp, where all the inflammable matter is consumed; and when we add to this all the expenses of the manufacture and gas establishment, it is evident, that the cost of this light must be considerably increased, unless the oil acquires by its conversion into gas some new illuminating vir- tue which it does not possess in its raw state, a circumstance which has indeed been asserted, but never proved.” Such being the comparative economy of the two gases, let us now consider their respective qualities. On this point it is agreed on all hands that the oil is superior. In the first place, it is free from that sulphureous matter which rises along with the coal gas, from which it is difficult to deprive this latter gas, and the effect of which is not only to corrode the pipes, and all the internal fittings of the apparatus exposed to the gas, but also to tarnish the plate and gilding of the apartment in which the gas is burned. From this contamination the oil gas is entirely free, and this constitutes its great advantage. But, on the other hand, it cannot be denied that the plans which have been devised for purifying the coal gas have had consi- derable success. In Glasgow, and even in Edinburgh, where the coal is of inferior quality, the gas is now manufactured in such purity, that the presence of sulphur cannot be detected in it by the most delicate tests; and in fact it is said by these com- panies to be now incapable of tinging either plate or gilding any more than oil gas.t established, it would be of great importance. The best proof of it which could be given would be the adopting of the coal gas by jewellers, among whom its use was discontinued at the first trial, on account of its injurious effects, and has since, we believe, not been resumed by any of them. Another advantage ascribed to the oil gas is its freedom from any unpleasant smell. If this be meant of the gas itself as it escapes from the pipes by leakage or otherwise, the oil gas is in this respect certainly very little, if at all, superior to coal. We are con- vinced, indeed, from experience, that neither of them could well be tolerated, if allowed to escape unburnt; and it would be difficult to decide which of the two smells is the most offen- Edinburgh gas, which is generated from different sorts of coal, and for gas cf an average quality, the proportion has been found as 2+ to 1. Besides these authorities, an interesting set of experiments have been made by Messrs. Heropath and Rootsey on the Bristol gas, and their proportion is that of 24 to 1, or 2 to 1. Making due allowance, then, for the bias of the respective parties, we are certainly not underrating the oil gas when we assume it, as above, at 2% times superior to coal gas. * Sir W. Congreve observes, that “there can be no doubt that the light thus produced by oil gas is much cheaper than that produced by the direct burning of the oil, and some have even estimated the gain at 25 per cent. It would require, however, strong proof to substantiate this fact, and the experiments of Heropath and Rootsey of Bristol shew, on the contrary, a loss of 28 per cent. - --ºra-se 'sive. case, prevent any unpleasant effects. difference in this respect. If this fact could be satisfactorily But with proper attention on the part of the company, the escape of the gas can be entirely prevented, as is remarked by Mr. Tait, engineer, London, in his Report to the Dundee Company. “As to the smell of oil gas,” says he, “being less offensive in rooms than coal gas, this is a mere matter of taste. For my own part, I would sooner tolerate the latter; but nei- ther of them produce any smell whatever, if the services are secured, and the joints properly cemented.” But if the smell refers to the effect on the air of the robm by the burning of the gases, to the heat and closeness, to the smokiness, or to any other disagreeable vapour arising from any of the gases more than another—in this respect the oil certainly has the advan- tage. Much depends on the way in which the burners are: managed, a proper attention to which will, perhaps, in either But on this point we have no satisfactory information. - : “Oil gas,” say Taylor and Martineau, “burns with a far purer and more brilliant light than coal gas.” With good coal gas we cannot say that we have ever perceived a very material Besides these, there are various minor points of comparison between the two gases, on which, however, it is unnecessary to enlarge ; and in regard to the advantage which oil gas possesses, of being more easily gene- rated, and without any of those nuisances to which the coal gas establishments are subject, also its being less bulky, and held therefore in gasometers, and distributed in pipes of half the usual dimensions, these advantages are all involved in the TICC, - p Such, then, are a few of the facts regarding these two species of light, which we have endeavoured to collect, from different sources, for the information of our readers. It is evident, on the whole, that the oil gas, though it will be a much cheaper light than candles, will yet here be considerably dearer than coal gas ; but then it is purer, and burns with a brighter light; and, as Mr. Dewey of New York remarks, if some are content with fine, there is no reason why others should not prefer super- fine. This, of course, is a matter of choice with the public; and it is not our intention, by the above remarks, to recom- mend either the one or the other light in preference, but merely to state the facts which have come to our knowledge.—Cal. Mercury. - GASKET, a sort of plaited cord fastened to the sail-yards of a ship, and used to furl or tie up the sail firmly to the yard by wrapping it round both, six or seven times, the turns being at a competent distance from each other. Bunt GAskET, is that which supports or ties up the bunt of the sail, and should consequently be the strongest, as having the greatest weight to support; it is sometimes made in a peculiar manner. * Quarter GAsket, used only for large sails, and is fastened about half-way out upon the yard, which part is called the quarter. . The Yard-arm GAsket, is made fast to the yard-arm, and serves to bind the sail as far as the quarter-gasket on large yards, but extends quite into the bunt of small sails. GASSENDI, Peter, a celebrated French philosopher and astronomer, was born in a village in Provence, in 1592. He very early discovered great talents, and at the age of 16 was made professor of rhetoric at Digne, and soon after professor of philosophy at Aix. Gassendi died in 1655, in the 63d year of his age, leaving his manuscripts to M. de Monmor, his friend and executor. - + Mr. Neilson, engineer, Glasgow, in his judicious Report to the Dundee Company, observes, “the gas at present made in the Glasgow works seems to be entirely free of it, (the sulphuretted hydrogen,) and will not tinge either silver or gilding, nor can the acetate of lead, which is reckoned a delicate test, discover in it any of this offensive mixture.” Besides the sul- phuretted hydrogen, however, the gas contains hydro-sulphuret of ammonia, which proves injurious to copper and iron gas-pipes, and of which it is still more difficult to deprive the gas. Mr. Dewey of New York states, that this has been done by Mr. James Neilson of the Glasgow gas works, but that “owing to the expense of the process, and the low price at which the gas is furnished to the customers, it has not been carried fully into effect.” Great improvements, therefore, may yet be looked for in the purification of coal gas, the manufacture of which presents a rich and interesting field for the researches of the chemist. 380 G. A U G. A. V DICTIONARY OF MECHANICAL SCIENCE. GASTERosTEUs, the Stickle Back, in Natural History, a genus of fishes of the order of thoracici. There are thirteen || species, G. aculeatus, or three-spined stickle-back, is found in almost all the fresh waters of Europe, and is about three inches long, and in the beginning of the summer, displays the most beautiful combination of bright-red, fine olive-green, and sil- very whiteness. . It is extremely active and rapid, and is particularly injurious in fishponds, as it devours the spawn of the fish. - - - * GASTRIC JUICE, a fluid of the utmost importance in the process of digestion. It does not act indiscriminately on all substances, nor is it the same in all animals, nor does it con- tinue always of the same nature, even in the same animal, changing according to circumstances; it acts with a chemical energy in dissolving food; attacking the surface of bodies, and uniting to the particles of them. It operates with more energy and rapidity the more the food is divided, and its action is increased by a warm temperature. The food is not merely reduced to very minute parts; its taste and smell are quite changed; its sensible properties are destroyed; and it acquires new and very different ones. This fluid does not act as a fer- ment, it is a powerful antiseptic, and even restores flesh already puirefied. GASTROBRANCHUS, in Natural History, a genus of fishes of the order cartilaginei. It is characterized by the cir- cumstance of exhibiting no traces of the existence of such an organ as the eye. It will often enter the mouths of fishes fixed on the hook of the angler, and gnaw a passage through their bodies, devouring all but the bones and skin. Its substance is so highly glutinous, that a large vessel of sea water will, in a short time after the living coecus is placed in it, become of the consistence of a jelly. GATE, in Architecture, a large door, leading or giving entrance into a city, town, castle, palace, or other considerable building; or a place giving passage to persons, horses, coaches. or waggons, &c. GATT, is the same as Channel, and is a term constantly used on the Flemish coast and in the Baltic for that purpose. GAUGER, a king’s officer appointed to examine all tuns, pipes, hogsheads, and barrels, of wine, beer, ale, oil, honey, &c. and give them a mark of allowance before they are sold in any place within the extent of his office. - GAUGE POINT of a solid, is used to denote the diameter of that circle, whose area is expressed by the same number as is equal to the number of cubic inches in the solid. Thus 17-15 being the diameter of a circle whose area is 231; this is called the gauge point of the wine gallon, which contains 231 cubic inches. GAUGING, the art or act of measuring the capacities of all kinds of vessels, and thence ascertaining the quantity of liquor which they contain. Gauging forms a part of mensuration, and is treated of by most authors who have written on the latter subject; this, however, is generally with reference to regular figures, as the frustums of cones and conoids, of para- bolic, hyperbolic, and elliptic spindles, &c. But as casks are seldom of any exact forms, these rules must be regarded as merely theoretical, and not applicable to the common cases that occur in practice. To remedy the inconvenience arising from such a number of rules, and at the same time to abridge the labour attendant on several of them, we will give one gene- ral rule for all cases, exceedingly simple in its application, and which is as follows: Add into one sum, 39 times the square of the bung diameter, 25 times the square of the head diameter, and 26 times the product of those diameters; multiply the sum by the length of the cask, and divide the pro- duct by 114; then this last quotient divided by 231 will give the wine gallons, and divided by 282 will give the ale gallons. Or, (39 B2 + 25 H2 + 26 BH) × 114 is the content in inches; which being divided by 231 for wine gallons, or by 282 for ale gallons, will be the content. Exam. Let the length of a cask be 40 inches, the bung diameter 32, and the head diameter 24, . Here . . . . . . . . . . . . . . . . . . . . . . 82° X 39 = 39936 - and. . . . . . . . . . . . . . . . . . . . . . .24° x 25 - 14400 and................ 32 × 24 × 26 = . 19968 - the sum … - 74304 multiplied by . . . . . . . . . . . . . . . . 40 and divide by............ 114)2972160 26071 cub. in. gallons, or divided by gives . . . . . . . . . this divided by 231 gives 282 gives 92 ale gallons. - But the common practice of gauging is performed mechani- cally, by means of the gauging or diagonal rod, or the gauging sliding rule, the description and use of which are as follow. GAUGING, or Diagonal Rod, is a rod or rule adapted for determining the contents of casks, by measuring the diagonal only, viz. the diagonal from the bung to the extremity of the opposite stave next the head. It is a square rule, having four sides or faces, being usually four feet long, and folding toge- ther by means of joints. Upon one face of the rule is a scale of inches, for taking the measure of the diagonal; to these are adapted the areas, in ale gallons, of circles to the corresponding diameters, like the lines on the under sides of the three slides in the sliding rule, described below. And upon the opposite face are two scales, of ale and wine gallons, expressing the contents of casks having the corresponding diagonals; and these are the lines which chiefly constitute the difference between this instrument and the sliding rule; for all the other lines upon it are the same with those in that instrument, and are to be used in the same manner. • * To use the Diagonal Rod. Unfold the rod, and put it in at the bung-hole of the cask to be gauged, till its end arrive at the farthest possible distance from the bung-hole, and note the inches and parts cut by the middle of the bung; draw out the rod, and look for the same inches and parts on the opposite face of it, and annexed to them are found the contents of the cask, both in ale and wine gallons. - Eram. Let it be required to find, by this rod, the content of a cask whose diagonal measures 344 inches; which answers to the cask in the foregoing example, whose head and bung diameters are 32 and 24, and length 40 inches; for if to the square of 20, half the length, be added the square of 28, half the sum of the diameters, the square root of the sum will be 34.4 nearly. Now, to this diagonal 344 corresponds upon the rule, the content 91 ale gallons, or, 111 wine gallons; being but one less than the content found by the former general rule above given. The GAUGING Rule, or Sliding Rule, is a sliding rule particu- larly adapted to the purposes of gauging. It is a square rule, of four faces or sides, three of which are furnished with'sliding pieces running in grooves. The lines upon them are mostly logarithmic ones, or distances which are proportional to the logarithms of the numbers placed at their ends; which were fine lines placed upon rulers, by Gunter, for expeditiously per- forming arithmetical operations, using a pair of compasses for taking off and applying the several logarithmic distances; but instead of the compasses, sliding pieces were added, by Mr. Thomas Everard, as more certain and convenient in prac- tice, from whom this sliding rule is often called Everard’s Rule. GAURS, an ancient sect of the Magicians in Persia, who profess the worship of one God alone, the belief of a resurrec- tion and a future judgment, and utterly detest all idolatry. They perform their worship before fire, for which they have an extraordinary veneration, as believing it to be the most perfect emblem of the Deity. - - GAUT, a term made use of in the East Indies, to demote a passage or road from the coast to the mountainous or upland country. - - GAUZE, in Commerce, a thin transparent stuff, sometimes woven with silk, and sometimes only of thread, either plain or figured; the latter being sometimes worked with flowers of silver or gold on a silk ground. GAVELKIND, a tenure or custom in Kent, by which the lands of the father are, at his death, equally divided amongst all his sons; or the land of a deceased brother, in case he leaves no issue, among all his brethren. This custom came G. E. M. G. E. M. DICTIONARY OF MECHANICAL SCIENCE. 381 from our Saxon ancestors. The customs attending this tenure are, that the heir, at the age of fifteen, may give or sell his lands in gavelkind; and though the father is attainted of treason, and suffers death, the son inherits. A wife shall be endowed of a moiety of the gavelkind-lands, of which her husband died seised, during her widowhood. Likewise a husband may be tenant by courtesy of half his wife’s lands, without having any issue by her; but if he marries again, not having issue, he forfeits his tenantcy. GAZETTE, a printed account of the transactions of all the countries in the known world, in a loose sheet or half sheet. This name is with us confined to that paper of news published by authority of the government. The first gazette in England was published at Oxford, Nov. 7, 1665. GELATINE, in Chemistry, is one of the constituent parts of animal substances, and may be obtained by repeatedly wash- ing the fresh skin of an animal in cold water, afterwards boiling it, and reducing it to a small quantity by slow evaporation, and allowing it to cool. It then assumes the form of jelly, and becomes hard and semitransparent. It is a principal part both of the solid and fluid parts of animals, and is employed in the state of glue, size, and isinglass. GELD, in our old customs, a Saxon word, signifying money or tribute ; also a compensation for a crime. Hence wergeld was used for the value of a nuan slain, and Orsgeld, of a beast. GELLIBRAND, Henry, an English astronomer, having been professor of that science in Gresham College, was born in London 1597, and died in the same city of a fever in 1636, being only 39 years of age. acquaintance of Briggs, and wrote the preface, and attended to the publication, of the “Trigonometria Britannica,” Briggs having died before the completion of that great undertaking. GEMINI, The Twins, II. One of the Northern signs, being the third sign of the zodiac, and the last of the Spring signs. According to the fixed zodiac of Hipparchus, the Sun enters Gemini on the 21st of May. That is to say, the Earth, at that time, passes into the sign Sagittarius, and the Sun, as seen from the Earth, appears to have made his transit from Taurus into Gemini. According, however, to the recession of the equinoxes, the Sun enters Gemini on the 18th of June. The Earth is of consequence about to quit Sagittarius, and enter Capricornus. A still larger portion of the North Pole is now in the light than we observed in the last sign, and the days have proportionally increased in length, for the Sun rises at iv ho. 6 mi. A. M., and sets at VII ho. 54 mi. P. M. By dou- bling the time of his rising, we get the length of the night 8 ho. 12 mi., and by doubling the time of his setting, the length of the day is 15 hours 48 minutes. Bowndaries and Contents.-Gemini are bounded on the N. by Lynx, E. by Cancer, S. by Monoceros and Canis Minor, and W. by Taurus. There are 85 stars in this constellation; namely, two of the 2d magnitude, four of the 3d, six of the 4th, &c. The chief star is Castor, whose right ascension is 110° 46' 25", and its declination 32° 16'6". This star appears on the N. N. E. # E. point of the compass, at London, and it rises and culmi- nates as in the following Table : Merid. Alt. 70° 45' 6". Gellibrand was an intimate | MONTH. RISES. CULM. MONTH. RISES. CULM. ho. mi. ho. mi. l ho. mi. ho. mi. Jan. 2 55 A. | 12 34 M. July 3 0 M. 12 43 A. Feb. 12 45 A. | 10 23 A. Aug. 12 55 M. 10 35 M. Mar. 10 55 M. 8 34 A. Sept. 11 0 A. | 8 38 M. April 8 55 M. 6 41 A. Oct. 9 10 A. | 6 52 M May 7 0 M. 4 50 A. Nov. 7 15 A. | 4 55 M June 5 0 M. 2 47 A. || Dec. 5 10 A. | 2 50 M Castor passes vertical over the States of Barbary, Palestine, Persia, Cashmere, Thibet, Houan in China, Japan, Louisiana in North America, the southern parts of the United States, the Bermudas, &c. When Castor begins to rise, the club of Orion, and after it the star Betelgeux, appear; but by this time Pollux is fairly above the horizon. At the time those stars begin to rise on the N. E. by N. point of the horizon, Cepheus, Cygnus, and Lacerta, are in the zenith. Serpentarius declines in the W., leading with him Taurus Poniatowski. Procyon rises when Cassiopeia and Andromeda are in the zenith, and Canes Venatici in the Northern horizon. When Castor and Pollux come to the meridian, Canis Major appears in the Southern, Lyra and Cygnus in the Northern, Virgo in the Eastern hori- zon, and the Lynx occupies the zenith. Between the meridian and the E. we find Cancer and Leo; between the meridian and the W. Taurus and Aries; and between the zenith and the S. Canis Minor and the Unicorn. GEMMA, in Botany, a bud, a compendium of a plant seated upon the stem and branches, and covered with scales, to defend the tender rudiments from cold and external injuries, till their parts being unfolded, they acquire strength, and render any further protection unnecessary. In general, we may distinguish three kinds of buds; that containing the flower, that containing leaves, and that containing both flower and leaves. See BotANY and PLANTs. GEMS, or PRecious Stones, are sometimes found of regu- lar shapes, and with a natural polish; and sometimes of irre- gular shapes, and with a rough coat. The first sort may be considered as of the pebble kind, and are said to be found near the beds of rivers, after great rains; the others are found in mines, and in the clefts of rocks. The gems of the first sort were what the ancients most usually engraved upon ; these are commonly called intaglios; and they are mostly of a long oval figure, inclining to a point at each end, convex as well on the engraved face as on the others, with a ridge running from end , to end on the under side, which is hereby, as it were, divided into two faces ; both which are also, though not so distinctly, parted from the upper face, by another ridge running quite round the oval. The stone most commonly found engraved is the beryl. The next is the emerald; and then the jacinth. The chrysolite is but rarely found engraved; as are also the crystal, or oriental pebble, the garnet, and the amethyst. Of the beryl there are three species; the red, inclining to orange colour, transparent and lively; the yellow, of an ochre colour, and the white, com- monly , called the chalcedony, and the colour of sheer milk. These two last have less life than the first. The emerald is green, nearly of the colour of stagnated water; sometimes tolerably clear, but for the most part full of black and white specks. The jacinth is of a deep tawny red, like very old Port wine, but lively and transparent. The chrysolite is of a light green grass colour, and is supposed to have been the beryl of the ancients, transparent, but not lively. The crystal or oriental pebble is harder and more lively than the common rock crystal; is of a silvery hue, and but very little inferior to the white sapphire. The garnet is of the same colour as the jacinth, but more inclining to the purple, and not so lively. The amethyst is of a deep purple, transparent and lively. The following is a general table of what are usually called precious stones:–The beryl, red, yellow, or white; emerald, green; jacinth, of a deep tawny red ; chrysolite, of a light grass- green; crystal, or oriental pebble, of a silvery white; garnet, of a deep red claret colour; amethyst, purple; diamond, white; ruby, red or crimson coloured; emerald, of a deep green; aqua marina, of a bluish sea green, like sea water; topaz, of a ripe citron yellow; sapphire, of a deep sky blue, or of a silver white ; cornelian, red or white; opal, white and changeable; vermilion stone, more tawny than the jacinth. All these stones are more or less transparent: the following are all opaque :-The cat’s eye, brown; red jasper, called also thick cornelian, of the colour of red ochre; jet, black; agates, of various sorts; blood-stone, green, veined or spotted with red and white; onyx, consisting of different parallel strata, mostly white and black; sardonyx, of several shades of brown and white; agate-onyx, of two or more strata of white, either opaque or transparent; alabaster, different strata of white and yellow, like the agate-onyx, but all opaque; toad's eye, black; turquoise, of a yellowish blue inclining to green; lapis lazuli, of a fine deep blue. Of most of the species beforementioned, there are some of an inferior class and beauty. These are commonly called by jewellers occidental stones; they are mostly the produce of Europe, and found in mines or stone quarries; and are so named in opposition to those of a higher class, which are always accounted oriental, and supposed to be only produced in the East. The onyx, sardonyx, agate-onyx, alabaster of two colours or strata, as also certain shells of different coats, 5 E 382 G. E. N. G E N DICTIONARY OF MECHANICAL SCIENCE. were frequently engraved by the ancients in relief; and these sorts of engravings are commonly called cameos. They also sometimes ingrafted a head, or some other figure in relief, of gold, upon a blood stone. . . . . . . Besides which there are some antiques, mostly cornelians, that are covered with a stratum of white. This stratum has by some been looked upon as natural ; but it was really a sort of coat of enamel that was laid on. The stones esteemed the best for engraving upon, were the onyx and sardonyx; and next to them, the beryl and the jacinth. The ancients en- graved most of their stones, except the onyx and the sardonyx, just as they were found; their natural polish excelling all that can be done by art; but the beauty of the several species of onyx could only be discovered by cutting. . The merit of intaglios and cameos depends on their erudition, as it is termed, or the goodness of the workmanship, and the beauty of their polish. The antique Greek gems are most esteemed; and next to them the Roman ones, in the times of the higher empire. Lapidaries employ a considerable quantity of diamond in powder, which they use with *. instruments, to divide pebbles and precious stones. he small pieces of diamond of which the powder is made, are worth twenty-eight shillings a carat. The use of the diamond in this way is very extensive. Had nature withheld the dia- 'mond, the pebble, the agate, and a variety of other stones, would have been of little value, as no other substance is hard enough to operate upon them. In this way rock crystal from Brazil is divided into leaves, and ground and polished with diamond dust for spectacles, and other optical instruments. GeMs, Imitation of Antique, a method of taking the impres- sions and figures of antique gems, with their engravings, in glass of the colour of the original gem. The great care in the operation is, to take the impression of the gem in a very fine earth, and to press down upon this a piece of proper glass, softened or half melted at the fire, so that the figures of the impression made in the earth may be nicely and perfectly expressed upon the glass. The yellowish tripoli has been found best adapted for this purpose. - GENDARMES, or GENs D'ARMes, in the French armies, a denomination given to a select body of horse, on account of their succeeding the ancient gendarmes, who were thus called from their being completely clothed in armour. The appella- tion is now bestowed on both the horse and foot soldiers in France, who are employed in,the police of the country. They are chosen from all the rest of the army on account of their good behaviour, and enjoy superior pay and advantages. GENDER, among Grammarians, a division of nouns or names to distinguish the two sexes. GENEALOGICA ARB or, or Tree of Consanguinity, signifies a genealogy or lineage drawn out under the figure of a tree, with its root, stock, branches, &c. The genealogical degrees are usually represented in circles ranged over, under, and aside each other. - GENEALOGY, an enumeration of a series of ancestors; or a summary account of the relations and alliances of a person or family. GENERAL Issue, in Law, is that plea which traverses and denies at once the whole declaration or indictment, without offering any special matter, by which to evade it: it is called the general issue, because, by importing an absolute and gene- ral denial of what is alleged in the declaration, it amounts at once to an issue, or fact affirmed on one side, and denied on the other. This is the ordinary plea upon which most causes are tried, and is now almost invariably used in all criminal cases. It puts every thing in issue, that is, denies every thing, and requires the party to prove all that he has stated. It is a fre- quent question, what can be given in evidence by the defendant upon this plea, and the difficulty is, to know when the matter of defence may be urged upon the general issue, or must be spe- cially pleaded upog the record. In many cases, for the pro- tection of justices, constables, excise officers, &c. they are by act of parliament enabled to plead the general issue, and give the special matter for their justification under the act in evidence. - GENERAL of an Army, in the art of war, he who commands in encampment of the army; in the day of battle to choose out the most advantageous ground ; to make the disposition of the army; to post the artillery; and where there is occasion, to send his orders by his aides-de-camp. At a siege he is to cause the place to be invested; to order the approaches and attacks; to visit the works, and to send out detachments to secure his convoys. - - : Gener AL of Horse, and General of Foot, are posts next under the general of the army. General of the Artillery, has the charge of the ordnance. General, is also used for a particular march or beat of drum, being the first which gives notice for the infantry to be in readiness to march. General, is also used for the chief of an order of monks. . . . * GENERAL Terms, among Logicians, are those made the signs of general ideas. - - - GENERANT, or Genitum, that which is generated, or sup- posed to be generated, by the motion of any point, line, or figure. The generant is always one dimension higher than the generating quantity; thus a line is generated by the motion of a point, a surface by a line, and a solid by a surface. It is generally a theorem in geometry, that the measure of any gene- rant is always equal to the product of the generating quantity, drawn into the path of the centre of gravity of the latter, whether its motion be rectilineal or rotatory. So also, GENERATED, is used by mathematicians to denote what- ever is formed by the motion of a point, line, or surface; thus a line is said to be generated by the motion of a point, a sur- face by the motion of a line, and a solid by the motion of a surface. The same term is also sometimes used in a similar sense in arithmetic and algebra; thus 20 is said to be gene- rated by the two factors 4 and 5, or 2 and 10; a b of the factors, a and b, &c. - GENERATING LINE or FIGURE, in Geometry, is that line or figure, by the motion of which another figure or solid is sup- posed to be described or generated. In the fluxional analysis all kinds of quantities are supposed to be generated by the motion of other quantities, and the quantities thus generated are termed fluents. - GENERATION, in Mathematics, denotes the formation or description of any geometrical figure or magnitude by the motion of another quantity or magnitude, of a dimension one degree less. GENERICAL NAME, in Natural History, the word used to signify all species of natural bodies, which agree in certain essential and peculiar characters, and are therefore all of the game family or kind, so that the word used as the generical name, equally expresses every one of them, and some other words expressive of the peculiar qualities of figures of each are added, in order to denote them singly, and make up what is called the specific name. Thus the word rosa or rose, is the generical name of the whole series of flowers of that kind, which are distinguished by the specific names of the red-rose, the white-rose, the apple-rose, &c. GENESIS, in Mathematics, is nearly the same as gene- ration, being the formation of a line, surface, or solid, by the flowing of a point, line, or surface. Here the moving line or figure is called the describent, and the line in which the motion is made the dirigent. . - .g. GENEVA, GIN, a hot fiery spirit, too much used by the lower classes of people in this country, as a dram, and most injurious to their constitution and morals. A liquid of this kind was formerly sold in the apothecaries’ shops, drawn from the juniper-berry, but the liquor now sold under the name of geneva or gin, is composed of oil of turpentine and malt spirits. The Holland’s geneva is manufactured chiefly at Schiedam, near Rotterdam, from wheat and juniper-berries. GENIUS, in matters of Literature, &c. a natural talent or disposition to do one thing more than another; or the aptitude a man has received from nature to perform well and easily that which others can do but indifferently, and with a great deal of pains. . GENTIANA, in Botany, a genus of the pentandria digynia class and order. Natural order of rotaceae. Gentianae Jussieu. There are fifty-three species. The most remarkable is the lutea or common gentian, the root of which is an excellent chief. The office of the general is to regulate the march and l stomachic bitter. .” - G E O G. E. O. 383 DICTIONARY OF MECHANICAL SCIENCE. GENUS, among Metaphysicians and Logicians, denotes a number of beings which agree in certain general properties com- mon to them all. - - GENUs, in Natural History, a subdivision of any class or order of natural beings, whether of the animal, vegetable, or mineral kingdoms, all agreeing in certain common characters. GEOCENTRIC Latitude of a Planet, is its distance from the ecliptic as it is seen from the earth. Geocent Ric Place of a Planet, the place wherein it appears to us from the earth, supposing the eye there fixed. GEOGRAPHY, is the science which describes the surface of the earth; its various kingdoms, states, and empires; the rivers by which they are intersected, their mountains, woods, &c. The several kingdoms and states of the world we have already described under the respective words, Africa, Ame- rica, Asia, and Europe. We will, therefore, in this article, treat very briefly of the natural divisions of the earth, and what is properly termed physical geography. - Geography assigns to the earth the following grand divisions: —Europe, Asia, Africa, America, Australasia, or New Holland. Of the grand divisions of the earth, Asia has ever been esteemed the most populous; and is supposed to contain five hundred millions of souls, if China, as has been averred by the latest writers, comprises three hundred and thirty millions. The population of Africa may be estimated at thirty millions, of America at twenty millions, and one hundred and fifty mil- lions may perhaps be assigned to Europe. Modern discoveries have evinced that more than two-thirds of the globe is covered with water, which is contained in hollow spaces, or concavities, more or less large. vexities or protuberances of the globe consist of elevated uplands, sometimes crowned by mountains, sometimes rather level, as the extensive protuberance of Asia. In either case, long chains of mountains commonly proceed from those chief convexities in various directions, and the principal rivers usually spring from the most elevated grounds. The grandest concavity of this globe is filled by the Pacific Ocean, occupying nearly half its surface, from the eastern shores of New Holland to the western coast of America, and diversified with several groups of islands, which seem in a manner the summits of vast mountains emerging from the waves. This ocean receives but few rivers, the chief being the Amur from Tartary, the Hoan Ho and Kian Ku from China, while the principal rivers of America run towards the east. Next to this in magnitude is the Atlantic, between the Old and New Continents; and the third is the Indian Ocean. The seas between the arctic and the antarctic circles and the poles, have been sometimes styled the Arctic and Antarctic Oceans; but the latter is only a continuation of the Pacific, Atlantic, and Indian Oceans; while the Arctic Sea is partly embraced by continents, and receives many important rivers. . Besides these, there are other seas more minute, as the Mediterranean, the Baltic, and others still smaller, till we come by due grada- tion to inland lakes of fresh water. 2 The courses of rivers are sometimes marked by oblong con- cavities, which generally at first intersect the higher grounds, till the declivity becomes more gentle on their approach to their inferior receptacles. But even large rivers are found sometimes to spring from lowland marshes, and wind through vast plains, unaccompanied by any concavity, except that of their immediate course; while on the other hand, extensive vales, and low hollow spaces, frequently occur destitute of any stream. Rivers will also sometimes force a passage where nature has erected mountains and rocks against it, and where the concavity would appear to be in another direction, which the river might have gained with more ease. In like manner, though the chief mountains of Europe extend in a south- easterly and north-westerly direction, yet there are so many exceptions, and such numerous and important variations in other parts of the globe, as to render any attempt at a general theory vain. . - From the vast expanse of oceanic waters, arises in the ancient hemisphere that wide continent, which contains Asia, Europe, and Africa; and in the modern hemisphere the conti- ment of America, which forms a kind of separate island, divided by a strait of the sea from the ancient continent. In But the chief con- the latter, many discoveries of great importance to geography are of a very recent date, and it is not above eighty years since we obtained an imperfect idea of the extent of Siberia and the Russian empire, nor above thirty-five since ample, real, and accurate knowledge of these wide regions began to be diffused. So that, in truth, America may be said to have been discovered by Europeans before many parts of Asia; and of Africa our knowledge continues imperfect, while the latest observations, instead of diminishing, rather increase our idea of its extent, at least in regard to its insular appendages. But the grandest division of the ancient continent is Asia, the parent of nations, and of civilization: on the north-east and south, surrounded by the ocean; but on the west, divided . by an ideal line from Africa; and from Europe by boundaries not very strongly impressed by the hand of nature. The Rus- sian and Turkish empires, extending over large portions of both continents, intimately connect Asia with Europe. But for the sake of clearness and precision, geographers retain the strict division of the ancient continent into three parts, which, if not strictly natural, is ethical, as the manners of the Asiatic subjects of Russia, and even of Turkey, differ considerably from those of the European inhabitants of those empires. Physical Geography.—The prevailing theories of the present day are the inventions of Professor Werner, of Freyburgh, and Dr. James Hutton, of Edinburgh ; each of these has been ably supported and elucidated by the proofs, illustrations, and comparative views of acute and eloquent controversialists, and . two sects have been formed, under the appellation of Werne- rians and Huttonians. The first principle which the Werne- rian theory assumes is, that our globe was once covered with a sort of chaotic compost, holding, either in solution or suspen- sion, the various rocks and strata which now present them- selves to us as its exterior crust. From some unexplained cause, this fluid began first to deposit those bodies which it held in chemical solution, and thus a variety of crystallized rocks were formed. In these we find no vegetable or animal remains, . nor even any rounded pebbles; but in the strata, which lie upon the crystalline or first deposits, shells and fragments. occasionally occur; these, therefore, have been termed transi- tion strata ; and it is imagined, that the peopling of the world commenced about this period. The waters upon the earth began now more rapidly to subside, and finely divided parti- cles, chiefly resulting from disintegration of the first formations, were its chief contents;–these were deposited upon the transition rocks, chiefly in horizontal layers. They abound in organic remains, and are termed by Werner, Floetz, or secon- dary rocks. - It is now conceived, that the exposure of the primitive transi- tion and secondary rocks to the agencies of the wind and wea- ther, and to the turbulent state of the remaining ocean, produced inequalities of surface, and that the water retreated into low lands and valleys, where a further deposition took place, constituting clay, gravel, and other alluvial formations. There are also certain substances which, instead of being found in regularly alternating layers over the earth, are met with in patches; as rock-salt, coal, basalt, and some other. bodies which Werner hath called subordinate formations. Lastly, subterraneous fires have sometimes given birth to pecu- liar and very limited products; and these are called volcanic rocks. Such is Werner’s account of the production of rocks, which he arranges under the terms primary transition, secondary, alluvial, subordinate, and volcanic formations. - 's Hutton, looking upon the face of nature, gives a very diffe- rent account of the present order of things, and observes every thing in a state of decay; but as she has obviously provided for the regeneration of animal and vegetable tribes, the philo- sopher descries in this apparent destruction of the surface of the earth, the real source of its renovation. The stupendous mountains exposed to the action of the varying temperature of the atmosphere, and the waters of the clouds, are, by slow degrees, suffering constant diminution; their fragments are dislodged, masses are rolled into the valley, or carried by the rushing torrent into rivers; whence they are transported to the sea. The lower and softer rocks are undergoing similar, but more rapid destruction. The result of all this must be, the accumulation of new matter in the ocean, which will be # :: *.* *s 384 G. E. O. G E O DICTIONARY OF MECHANICAL SCIENCE, deposited in horizontal layers. Hutton perceives the transi- tion rocks of Werner, though not strictly crystalline, made up apparently of finely divided matter, more or less indurated; sometimes very hard in texture, and of a vitreous fracture; that this hardening is most perceptible when in contact with the primitive or inferior rock, which often pervades the transi- tion rocks in veins, or appears to have broken up or luxated the superincumbent masses. The transition or secondary rocks of Werner were, according to Hutton, deposited at the bottom of the ocean, in consequence of operations similar to those which are now active, and the primary rocks were formed beneath them by the operation of subterraneous fires; their crystalline texture, their hardness, their shape and fracture, and the alterations they have produced upon their neighbours, are the proofs of the correctness of these views. It is by the action of fire then, that rocks have been elevated, that strata have been hardened, and that those changes have resulted, which an examination of the earth's surface unfolds. The production of soils, and of alluvial lands, is considered as dependent upon causes the same as those referred to in the other theory. Hutton refers to fire as well as water, for the production of our present rocks ; the former consolidating, hardening, and elevating; the latter, collecting and depositing the strata. GEOLOGY, is the doctrine of the earth in its insentient, or unorganized frame, or of those masses of rock, mountains, strata, minerals, &c. which compose the earth. The science of geology, independently of the healthy cmployment it affords, is of great importance in a practical point of view. It very nearly concerns the miner, engineer, and drainer, and even the farmer and architect; and discloses a variety of indications highly useful in their respective pursuits: to the miner, the rocks containing metallic veins and coals; to the engineer, the association of hard rocks with soft; to the drainer, the intersection of a country by hard dykes, or veins impermeable to water; to the farmer, the best places for finding lime-stone, marl, and clay; and to the architect, the most durable stones for building. The stony masses of which the earth is composed, are nume- rous, and are found laid one above another, so that a rock of one kind of stone is covered by another speeies of rock, and this by a third, and so on. In this superposition of rocks, it has been observed, that their situation is by no means arbitrary; each occupies a determinate place, so that they follow one another in regular order from the deepest part of the earth's crust, which has been examined, to the very surface. Thus there are two things respecting rocks which claim our attention; namely, thcir composition, and their relative situation. But besides the rocks which constitute almost the whole of the earth's crust, there are masses to be considered traversing the rocks in a different direction, and known by the name of veins, as if the rocks had split asunder in different places from top to bottom, and the chasm had been afterwards filled up with the matter which constitutes the vein. It appears, therefore, that the subject naturally divides itself into three parts; I. The structure of rocks; 2. The situation; and 3. Veins. . . Of the Structure of Rocks.-Rocks may be divided into two classes: first, those composed of one mineral substance, and which are in reality simple rocks; secondly, we observe rocks that are compound, or composed of more than one mineral sub- stance. Cemented; composed of grains agglutinated by a cement, as sand-stone. Others that are aggregated; composed of parts connected together without a cement, as granite. The aggregated rocks are likewise of two kinds; namely, I. Indeterminate. Only one instance of this kind of aggregation has hitherto occurred, namely, in the older serpentine, where limestone and serpentine are so conjoined that it is difficult to say which predominates. II. Determinate, which are either 1. Single aggregated; or 2. Double aggregated. There are four kinds of single aggregated rocks; namely, 1, Granular; composed of grains whose length, breadth, and thickness are nearly alike, and which are of contemporaneous formation; as grunite sienite. 1. Slaty; composed of plates laid above each other; as mica slate. 3. Porphyritic; com- posed of a compact ground, containing in it crystals, which appear to have been deposited at the time the rock was formed; covering the second, and so on. as common porphyry. 4. Amygdaloidal; composed of a com- pact ground, containing in it vesicles which appear to have been afterwards filled up; as amygdaloid. There are five kinds of double aggregated rocks; namely, 1, Granular slaty; composed of slaty masses laid on each other. Every individual slate is composed of grains cohering together; or it is slaty in the great, and granular in the small ; as gneiss. 2. Slaty granular; composed of large granular masses cohering together; each grain is composed of plates; or the rock is granular in the great, and slaty in the small ; as topaz rock. 3. Granular porphyritic; granular in the small, and porphyritic in the great; as granite, green-stone frequently. 4. Slaty por- phyritic, slaty in the small, porphyritic in the great, as mica slate. 5. Porphyritic and amygdaloidal, at the same time ; as amygdaloid and basalt frequently. Of the relative Situation of Rocks,—The rocky masses, amount- ing to about sixty, are variously placed over each other, and occupy determinate situations, limestone above granite, &c. The rocks which constitute the nucleus and even crust of the earth, are thus every where the same, in the same situations with respect to each other, and they may all be divided into five classes: 1. The nucleus mass, nearest the centre, or the basis. of other formations. 2. Those which cover the first ; the third Therefore the first class, though covered by all the rest, never lie over any other class. These grand classes of rocks he has denominated formations, and distinguished them by the following specific names. 1. Primitive formations. 2. Transition formations. 3. Floetz, or horizontal formations. 4. Alluvial formations. 5. Volcanic formations. e The primitive formations are the lowest of all, and the allu- vial constitute the surface of the earth; for the volcanic are confined to particular points. Not that the primitive are always at a great depth, for very often they are at the surface, or even constitute mountains. In such cases, the other for- mations are wanting altogether. In like manner, the transi- tion, and other classes, may each in its turn occupy the surface or constitute the mass of a mountain. In such cases, all the subsequent formations are wanting in that particular spot. Each of these grand classes of formations consist of a great or small number of rocks, which occupy a determinate position with respect to each other, and which, like the great formations themselves, may often be wanting in particular places. Class 1. Primitive Formations. The rocks which constitute the primitive formations are numerous, and have been divided into seven sets, which constitute as many primitive formations. They are distinguished each by the name of that particular rock which constitutes the greatest proportion of the formation. And these seven sets of primitive formations are the following: . gº {: Newest primitive porphyry, e 9 tº tº 3. Mica slate, 6. Sienite, 4. Clay slate, 7. Newer serpentine. The granite is the undermost, the sienite the uppermost, of the primitive formations. Granite is scarcely mixed with any other rock; but in gneiss, mica-slate, and clay-slate, there occur beds* of old porphyry, primitive trap, primitive limestone, old serpen- tine, quartz rock, which constitute formations subordinate to gneiss, mica-slate, and clay-slate. Gypsum is met with in beds of mica-slate, and old flint in clay-slate. These, therefore, are formations subordinate to mica and clay-slate. Thus, besides seven principal, there are seven subordinate formations, inter- spersed among the second, third, and fourth formations, to which we may add topaz rock, lying over gneiss and under clay- slate, so that the primitive formations amount in all to 15. Granite is the oldest, and alluvial the newest formations. Class 2. Transition Formations, lying immediately over the primitive formations, consist only of 4 sets. 1. Gray-wacke; 2. transition lime-stone; 3. transition trap; 4. transition flint- Slate; all which alternate with each other, except the lime- stone, which seems to rest upon the primitive formations. It is in the transition rocks that petrifactions first make * A mountain composed of the same layers of stone is said to be strati- fied; but it is composed of beds, when the layers are of different kinds of stone. -- G. E. O G E O 385 DICTIONARY OF MECHANICAL SCIENCE. their appearance; and they always consist of species of corals and zoophytes, which do not at present exist, and which therefore we may suppose extinct. The vegetable petrifac- tions are likewise the lowest in that kingdom, such as fernes, &c. This remarkable circumstance has induced Werner to conclude, that the transition rocks were formed after the earth contained organic beings. Hence the name transition which he has imposed, as if they had been formed when the earth was passing from an uninhabited to an inhabited state. The date of their formation is conceived to be very remote, since the petrifactions which they contain are the remains of animal and vegetable species now extinct. It is in the transi- tion rocks, too, that carbonaceous matter makes its first appear- ance in any assignable quantity. Class 3. Floetz Formations. The next grand class of formations has received the name of floetz, because they lie usually in beds much more nearly horizontal than the preced- ing. When not covered by a succeeding formation, they form hills which do not rise to the same height as the primitive or transition. They contain petrifactions, more various in their nature than those which occur in the transition formations, and consist of shells, fish, plants, &c. indicating, that they were formed at a period when organized beings abounded. The floetz formations lie immediately over the transition. They comprehend a great number of individual formations, each of which affects a particular situation. The following table exhibits a view of these different formations in the order of their position, as far as is known. I. Old red sand-stone, 6. Second floetz or shell lime- 2. First floetz lime-stone, Stone, 3. First floetz gypsum with 7. Third sand-stone or free- rock-salt, - Stone, 4, Variegated sand-stone, 8. Chalk, 5. Second floetz gypsum, 9. Independent coal, 10. Floetz trap. . The floetz trap formation lies over the rest, pretty much as the newer porphyry and sienite do over the older primitive formations. e Class 4. Alluvial Formations. The alluvial formations con- stitute the great mass of what is actually the earth's surface. They have been formed by the gradual action of rain and river water upon the other formations, and may be considered as very recent formations, or rather as deposites, the formation of which is still constantly going on. They may be divided into two kinds, those deposited in the valleys of mountainous districts, or upon the elevatcd plains which often occur in mountains; and those deposited upon flat land. The first kind consist of sand, gravel, &c. which constituted the more solid parts of the neighbouring mountains, and which remained when the less solid parts were washed away. They sometimes con- tain ores, (particularly gold and tin,) which existed in the neigh- bouring mountains. Sometimes the alluvial soil is washed, in order to separate these ores. On mountain-plains beds of loam are found. The second kind of alluvial deposite, or that which occupies the flat land, consists of loam, clay, sand, turf, and calctuff.” Here also occur earth and brown coal, (in this mineral amber is found,) wood coal, bituminous wood and bog iron-ore. The sand contains some metals, among others gold. The calctuff is a chemical deposite, and extends widely. It contains, plants, roots, moss, bones, &c. which it has encrusted. The clay and sand often contain petrified wood, and likewise skeletons of quadrupeds. * Class 5. Volcanic Formations. The volcanic formations are of two kinds; namely, pseudo-volcanic and the true volcanic. The pseudo-volcanic consists of minerals altered in conse- quence of the burning of beds of coal situated in their neigh- bourhood, Porcelain jasper, earth slag, burnt clay, columnar clay-iron-stone, and perhaps also polishing slate, are the mine- rals which have been thus altered. The real volcanic minerals are those which have been thrown out of the crater of a volcano. They are of three kinds. 1. Those substances which having been thrown out from time to time, have formed the crater of the mountain. 2. Those which have been thrown out of the • Stalactic or calcareous tufa, 40, crater in a stream, and rolled down the mountain ; they consti- tute lavas. 3. The water which is occasionally thrown out of volcanoes, containing ashes and other light substances, gra- dually evaporating, leaves the earthy matter behind, it: this substance constitutes volcanic tuff. - Until lately, the cause of volcanic fire was referred to sul- phur, coal, and other inflammable matter, supposed to be burning in immense masses in the bowels of the earth; but the products of volcanic irruptions by no means agree with such an explanation. Earthy, alkaline, and metallic bodies, form the lava, and as the products of combustion always have a reference to the combustible, such matters were not likely to be produced from sulphur and coal. We have only to suppose the access of water to large masses of different metals, and that it is decomposed by a galvanic action, as exemplified in experiments where copper and zinc are used in voltaic batteries. By these means, immense volumes of hydrogen gas are let free as the metals are oxi- dized. The violence of the action sets fire to the hydrogen, and the accumulated heat is so intense as to cause the fusion of every surrounding substance. By this theory, we are in pos- session of all the knowledge that is wanted to produce the tremendous effects of earthquakes and volcanoes:—for what power can resist the expansive force of steam? What power can resist the sudden evolution of gaseous fluid, accompanied by torrents of the earth in a state of fusion, which such a con- currence of circumstances must give rise to, and which are the actual concomitants of volcanic irruptions? Of Veins.—Veins are mineral repositories which cut through the strata of which a mountain is composed, and which are filled with substances different from the rocks through which they pass. If we suppose, that the mountains in which veins occur were split by some means or other, and that the rifts thus formed were filled up by the matter which constitutes veins, we shall have a clear notion of these mineral repositories, and which are distinguished from beds by their direction, it being either perpendicular to the stratifications, or at least in an angle with it. Sometimes the strata through which veins pass are merely separated from each other; so that if we cut through the vein, we find the same.strata of the rock on both sides of it; but sometimes also the corresponding strata on one side are lower than on the other, as if the portion of the rock on one side of the vein had sunk a little, while the portion on the other side kept its original position. In such cases the side of the rock against which the vein leans, or the floor of the vein, has always its strata highest up ; whilst the strata of the portion of rock which leans over the veins, or the roof of the vein, are always lowest. So that this is the portion which appears to have sunk. Such a change of position in the strata is known in this country by the name of a shift. - In considering veins, there are two circumstances which claim our attention: namely, 1st. The shape of veins; and, 2dly. The substances with which they are filled. 1. All those mineralogists who have had the best opportunity of examining the shape of veins with correctness, represent them as widest above, and diminishing in size as they deepen, till at last they terminate in a point, as if they had been origi- nally fissures. Sometimes, indeed, veins widen in different parts of their course, and afterwards contract again to their former size; but more commonly they continue diminishing to their extremity. - 2. Sometimes these veins are either partially or entirely empty. In that case they are denominated fissures ; but most commonly they are filled with a matter more or less different from the rock through which they pass. Sometimes the vein is filled up with one species of mineral. Thus we have veins of calcareous spar, of quartz, &c.; but when a vein is of any size, we usually meet with a variety of substances: these are dis- posed in regular layers always parallel to the sides of the vein, and they follow in their position a very regular order. One species of mineral constitutes the centre of the vein; on each side of this central bed the same layers occur in the same order from the centre to the side of the vein. To give an example; the vein Gregorius, at Freyberg, is composed of mine layers or beds. The middle of the vein consists of a layer of calcareous spar; on each side of this is a layer con- 5 F 386 c e o G. E. O DICTIONARY OF MECHANICAL SCIENCE. sisting of various ores of silver mixed together; on each side of this a layer of brown spar; on each side of this a layer of galena; on each side of this again, and contiguous to the side of the vein, is a layer of quartz. - - The following diagram will give the reader some notion of the relative position of these layers:— à ſ Cl - +. tº +: º Gneiss § | 3 || 3 || 3 ||3: Gneiss 3- || > || 3 || 4 || 3- - k rock. : ; ; * 3 || 3 || c | * | . . . . . IOCK, S | 3 || 5 * a | 3 || S | ſº * | < | < | sº c || > 3 ||3| 3 || $ || 3 || 9 || 3 || 3 || 3 § {Tº || 3 |: Tº |: S. Tº # Gºldblº Ign lo Jú, lºo Colcº Sometimes the number of layers of which a vein is composed greatly exceeds this. Werner describes one in the district of Freyberg, in which the middle layer is calcareous spar, having on each side of it no less than thirteen layers arranged in the very same order. Almost all the mineral substances which occur in the mass of rocks have been found in veins. We sometimes find them filled with different well-known stony bodies, as, granite, porphyry, limestone, basalt, wacke, green-stone, &c.; veins of quartz, clay, felspar, &c. are equally common. Pit-coal and common salt, and almost all the metals, like- | wise occur in veins. Some veins are filled with water-worn pebbles, others with loam; sometimes with petrifactions. Werner supposes that they were originally fissures formed in the rocks, and that they were all gradually filled by minerals deposited slowly from above, while the rocks in which they occur were covered by water, and that they were filled at the same time that the different formations were deposited. . This theory he has supported in his book on Weins, by a very complete enumeration of all the circumstances respecting their structure and appearances. He has shewn that they resemble fissures very exactly in their shape and direction; and that as they contain petrifactions and minerals altered by the action of water, they must of necessity have been filled from above. Veins of course, according to this theory, are newer than the rocks in which they occur; and when two veins cross, that is obviously the newest which traverses the other without inter- ruption, as the fissures constituting the second vein must have been formed after the first vein was filled up. When different veins contain the same minerals arranged in the same order, he conceives that they were filled at the same time, and says, that such veins belong to the same formation. When they differ in these respects, they belong to different formations. From the position of the respective veins with regard to each other, he deduces their relative age; and from this draws inferences respecting the relative age of the different mine- ral substances that occur in veins, similar to the inferences drawn respecting the age of the rocks which constitute the grand classes of formations. GEOMETRY, denotes one of the most general and import- ant of the mathematical sciences; and according to the present acceptation of the term, may be defined the science of exten- sion, or of magnitudes, considered simply, generally, and abstractedly; or rather, it is that science which treats of the relative magnitudes of extended bodies. Geometry is dis- tinguished into several denominations, as analytical, elementary, practical, &c. Elementary GeoMETRY, is that which treats of the properties and proportions of right lines and right-lined figures, as also of the circle and its several parts, and is either; theoretical or practical. - Theoretical GeoMETRY, has for its object the demonstration of certain geometrical propositions. Practical GeoMETRY, relates to the performance of certain geometrical operations, such as the construction of figures, and the drawing of lines in certain positions, as parallel, perpendi- cular, &c. to other given lines. - GeoMETRY of the Compass, is a modern branch of practical geometry, in which all the problems are performed by means of the compasses only. The most approved modern works on the elements of geo- metry are those of Euclid, as translated by Simson, Ingram, and Playfair; and the treatises of Professor Leisle, and M. Legendre. In practical geometry, we may recommend the works of Mallet, Clavins, Tacquet, and Ozanam. In analyti- | cal geometry, those of Mongé and Garnier. Prob, 1, fig. 1.--To bisect a given line A. B.—1. From the points A, B, as centres, with any distance greater than half A B, describe arcs cutting each other in c and d. 1. Draw the line c d and the point E, where it cuts A B, will be the middle of the line required. - Prob. 2, fig. 2.-From a given point C, in a given right line A B, to erect a perpendicular. When the point is near the mid- dle of the line: 1. On each side of the point C take any two equal distances C d and C e. 2. From d and e, with any radius greater than C d, or C e, describe two arcs cutting each other inf. Fig. 1. Fig. 2. º ... If Sº - >|< /|\ f t —ll-l- -KTTE f D. \ f \. / º . A Ž - A d O e TB 3. Through the points f, C, draw the line f C, which will be the perpendicular required. Fig. 3. When the point is at, or near, the end of the line.—1. | Take any point d above the line, and with the radius or dis- tance d C, describe the arc e Cf, cutting A B in e and C. 2. Through the centre d and the point e, draw the line e df, cut- ting the arc e C f, in f. 3. Through the points f and C, draw the line f C, and it will be the perpendicular required. ... . Prob. 3, fig. 4.—From a given point C, without a given right line A B, to let fall a perpendicular.—1. From the point C, with any radius, describe the arc de, cutting A B in e and d. 2. From the points e, d with the same, or any other radius, describe two arcs on the other side of the line, cutting each other in f. , 3. Through the points C, f, draw the line C Dj, and CD will be the perpendicular required. - JFig. 3. Fig. 4. f. C a’ - D A. ZSL* B A-2s –C B >. Prob. 4, fig. 5.-At a given point D, upon the right line D E, to make an angle equal to a given ångle a B b.—1. From the point B, with any radius, describe the are a b, cutting the legs 3 a, Bºb, in the points a and b. 2. Draw the line D E, and from the point D, with the same radius as before, describe the arc ef, cutting DE in e. 3. Take the distance b a, and apply it to the arc ef, from e to f. 4. Through the points D f, draw the line Df, and the angle e Df will be aqual to the angle b Ba, as was required. Prob. 5, fig. 6.—To divide a given angle A B C into equal angles.—1. From the point B, with any radius, describe the arc A C. 2. From A and C, with the same, or any other radius, describe arcs cutting each other in d. 3. Draw the line B d, and it will bisect the angle A B C into three equal angles G E O G E O DICTIONARY OF MECHANICAL SCIENCE. 387 Prob. 6, fig. 7.— . ig. 6. To trisector divide, Fig. 5. Fig a right angle A B C - T} into three equal an- (2. gles.—1. From the point B, with any radius BA, describe the arc A. C., cutting the legs B.A., and BC, in A and C. 2. From the points A, and C, with the ra- dius A B, or B C, cross the arc A C JFig. 7. Fig. 8. 69 3. ſ zz— \ & B, A- B in d, and e. 3...Through the points e, d, draw the lines B e, B d, and they will trisect the angles as was required. Prob. 7, fig. 8.—Through a given point C, to draw a line parallel to a given line, A. B.—1. Take any point d, in A B, upon d and C, with the distance C d, describe two arcs e C, and df, cutting the line A B in e and d. 2. Make df equal to c C; join Cf, and it will be parallel to A B as required. Fig. 9. When the parallel is to be at a given distance EF from A B.—1. From any two points c and d, in the line A B, with a radius equal to E F, describe the arcs e and f. 2. Draw the line C D to touch those arcs without cutting them, and it will be parallel to A B, as was required. Prob. 8, fig. 10.—To draw a tangent to a given circle, that shall pass through a given point A.—1. From the centre O, Fig. 9. Fig. 10. E—ſº Tol c—º :=D >~~ P-S Jº C’ dº º draw the radius O.A. 2. Through the point A, draw DE per- pendicular to OA, and it will be the tangent required. Prob. 9, fig. 11.--To draw a tangent to a circle, or any seg- ment of a circle A B C, through a given point B, without making use of the centre of the circle.—1. Take any two equal arcs Bd, de, upon the circle, from the given point B, and draw the chord e B. 2. Upon B, as a centre, with the distance B d, describe the arc falg, cutting the chord e B in f. 3. Make dig equal to df, through g draw g B, and it will be the tangent required. … Prob. 10, fig. 12.—A circle A B C being given, and a tangent C H to that circle, to find the point of contact.—1. Take any point e, in the tangent CH, and join e G. 2. Bisect e G in f; and with the radius fe, or f G, describe the semicircle e C G, cutting the tangent and the circle in C, it will be the point required. Fig. I1. Fig. 12. Prob. 11, fig. 13.—Given three points A, B, C, not in a straight line, to draw a circle through them.—1. Bisect the lines AB, and BC, by perpendiculars, meeting at d. 2. Upon d, with the distance, dA, dB, or d C, describe ABC, it will be the circle required. . t Fig. 13. <º Č V7 Fig. 14. A. Prob. 12, fig. 14.—In a given triangle, A, B, C, to inscribe a circle.—1. Bisect any two angles A and C, with the lines AID, and CD. 2. From D, the point of intersection, let fall the perpendicular D E, it will be the radius of the circle required. Prob. 13, fig. 15.—In a given square A B C D, to inscribe a regular octagon.—1. Draw the diagonals A C, and D B, inter- secting ate. 2. Upon the points A, B, C, D, as centres, with a radius e C, describe arcs, he l, ke n, m eg, fe i. 3. Join frt, m h, ki, lg, it will be the octagon required. Prob. 14, fig. 16.—In a given circle, to inscribe an equilateral triangle, an hexagon, or a dodecagon. For the equilateral triangle.—1. Upon any point A, in the circumference with the radius A. G., describe the arc B G F. 2. Draw B F, make B D equal to B F. 3. Join D F, and B D F will be the equilateral I’ig. 16. Fig. 15. A £ Z. TX Mº-SV ſ J. * #-F#–3–3 triangle required.—For the hexagon. Carry, the radius A G six times round the circumference, the figure A B C D EF will be the hexagon.—For the dodecagon. Bisect the arc AB in h, and Ah being carried twelve times round the circumference, will also form the dodecagon. Prob. 15, fig. 17.—In a given circle to inscribe a square or an octagon.—1. Draw the diameters A C and BD, at right angles, 2. Join AB, BC, CD, D A, and A B C D will be the square, For the octagon. Bisect the arc. A B in E, and A E being carried eight times round, will also form the octagon. Prob. 16, fig. 18.-In a given circle, to inscribe, a pentagon, or a decagon. For a pentagon.—1. Draw the diameters AF and GH, at right angles, cutting each other in I., 2. Bisect GI in f, upon f, with the distance off A, describe the are Ag; Fig. 18. Fig. 17. # upon A, with the distance Ag, describe the arc g E cutting the circle in E. 3. Join A E, and carry it round the circle five | times, then will A B C D E be the pentagon required.—For the decagon. Bisect the arc A E in i, and Di being carried ten times round, will also form the decagon. 388 G. E. R. G. E. O. DICTIONARY OF MECHANICAL SCIENCE. Prob. 17, fig. 19.—Upon a giv- en line A B, to describe an equi- lateral triangle. 1..Uponthe points A and B, with a radius equal to AB, describe arcs cutting eachother AI at C. 2. Draw - A C, and B C, it will be the triangle required. Prob. 18, fig. 20,-To make a triangle, whose three sides shall be equal to three given lines D,E,F, any two of which are greater than the third,—1. Draw A B equal to the line D. 2. Upon A, ~C F A E B D- with the distance E, describe an arc at C. 3. Upon B, with the distance F, describe another arc, intersecting the former at C. 4. Draw AC and CB, and A B C will be the triangle required. i Prob. 19, fig. 21-To make a trape- zium equal, and similar to a given trape- zium A B CD, -1. Divide the given trapezium A B C D into two triangles, by a diagonal A.C. 2. Make EF equal to AB, upon E F construct the triangle EFG, whose three sides will be respec- tively equal to the triangle A B C. 3. Upon E G, which is equal to A C, con- struct the triangle E G H, whose two sides E H, and GH, are respectively equal to A D and C D, then E FG H will be the trapezium required. In the same manner may any irregular polygon be made equal and similar to a given irregular polygon, by dividing the given polygon into triangles, and constructing the triangles in the same manner in the required polygon, as is shewn by figures. Prob. 20, fig. 22.--To make a triangle equal to a given tra- pezium ABC D.—1. Draw the diagonal BD, make CE parallel to it, meeting the side A B, produced in E. 2. Join D E, and A DE will be the triangle. ... Prob. 21, fig. 23.--To make a triangle equal to any given right-lined figure A B C D E.—I. Produce the side A B both ways at pleasure. 2. Draw the diagonals AD and B D, and make E F and C G parallel to them. 3. Join D F, D G, then D F G will be the triangle required. Much after the same manner may any other right-line figure be reduced to a triangle. Fig. 22. Fig. 23. |D Fig. 21. C C A. B E. 13 A B Prob. 22, fig. 24.—To reduce a triangle A B C to a rectangle. —1. Bisect the altitude A F in G, through G draw E D parallel to BC. 2. From C e * draw CD per- Fig. 24. Fig. 25. pendicular to BC, and B E parallel to CD, then B C D E will be the rect- angle required. Prob. 23, fig. 25.--To make a F. K. rectangle, haw- ; - • L & EI ing a side equal R - to a given line A B, and equal to a given rectangle CDEF- Produce the sides of the rectangle CF, DE, FE, and CD. 2. Make E G equal to AB, through G draw LH, parallel to DE, cutting CD produced at L. 3. Draw the diagonal LE, IB | 0 h, and produce it till it cut CF at K. 4. Draw KH, parallel to EG, then will E G H be the rectangle required. e Prob. 24, fig. 26.—To make a square equal to a given rect- angle A B C D.—1. Produce the side A B, make B E equal to B C. 2. Bisect A E in I, on I, as a centre with the radius IE or I A, describe the semicircle A H E. 3. Produce the side CB | to cut the circle in H, on BH describe the square BH G F, | and it will be the square required. . Prob. 25, fig. 27.--To make a square equal to two given squares A and B.—1. Make D E equal to the side of the Fig. 26. Fig. 27. H Ç jº Gr N IEE I B. A a ------, - s F A F T} C ID TD square A, and DF perpendicular to DE, equal to the side of the square B. 2. Draw the hypothenuse FE; on it describe the square EFG H, it will be the square required. Prob. 26, fig. 28.—To make a square equal to three given squares A, B, C.—1. Make DE equal to the side of the square A, and D F perpendicular to DE, equal to the side of the square B. 2. Join F E, draw F. G perpendicular to it. 3, Make FG equal to the side of the square C; join G. E., then GE will be the side of the square required. Prob. 27, fig.29.-Two right lines A B, and CD, being given, Fig. 28. - to find a third pro- g G. - - º |F- IBL F ID Jº - Fig. 29. portional.--1. Make an angle H E I at A—-ſº pleasure, from E, C D make EF equal to CD, and E G equal to A B, join F G. 2. Make E H equal to E G, and draw H I parallel to FG, then E I will be the third proportional required, that is, E F : E G : : E H : E I, or C D : A B :: A B : E I. zº Prob. 28, fig. 30.-Three right lines A C, CD, E F, being given, to find a fourth proportional.—1. Make the angle H G I at pleasure: from G make G H equal to A B; G I equal to CD ; and join H I. 2. Make GK equal to E F, draw KL through K parallel to HI, then G L will be the fourth propor- tional required; that is, ’G H : G. I. : : G. K. : G L, or A B : C D : : E F : G. L. Prob. 29, fig. 31.--To divide a given line A B, in the same proportion as another, C D is divided.—1. Make any angle KHI; and make H I equal to A B ; then apply the several Iº Fig. 30 Fig. 31. A. - - B To % F' | I, K LI w - parts of CD from H to K, and join K.I. 2. Draw the lines % hg, parallel to IK, and the line HI will be divided in h, i, k, l, as was required. : ---- GERANIUM, in Botany, Crane's Bill, a genus of plants belonging to the monadelphia class, and in the natural order ranking the 14th order Gruminales. . . . : GERARDIA, a genus belonging to the didynamia class, and in the natural method ranking under the 40th order. GERMEN, the seed-bud; defined by Linnaeus to be the base of the pistillum, which contains the rudiments of the seed; G I L G I L 389 DICTIONARY OF MECHANICAL SCIENCE. and, in progress of vegetation, swells, and becomes itself. Hence, • GERMINATION, among Botanists, comprehends the pre- cise time which seeds take to rise, after they have been com- mitted to the soil, and AIR and WATER are the agents of germination. Millet, wheat, and several of the grasses, rise in a day; spinach, beans, turnips, &c. in three days ; lettuce and dill in four; cucumber, gourd, melon, and cress, in five ; ra- dish and beet in six ; cabbage in ten; parsley in fifty ; peach, almond, and walnut in a year; and the sensitive plant retains its germinating virtue for thirty or forty years 1 GILDING, the application of gold to the surfaces of bodies, is performed in two ways. Wood, leather, paper, and soft substances, are gilt by fastening on gold leaf by some kind of cement; but metals are gilded by a chemical process, called water gilding ; while the former is called oil gilding, burnished gilding, and japanner's gilding. The instruments necessary for gilding are a cushion, knife, tip, and fitch, which are to be had in any colour shop. The gold leaf is either pure gold, (yellow); pale gold, (greenish ; ) or Dutch gold, that is, copper coloured by the fumes of zinc. The cushion receives the gold, the knife parts it; the tip, a tool made by fastening the long hairs of a squirrel’s tail between two cards, is used for taking up the gold leaf after it is cut, and laying it on the article to be gilded. A fitch pencil is used for the same purpose as the last, in taking up very small bits of gold leaf. A ball of cotton is used for pressing down the leaf, after it is laid on ; a large camel's hair brush for dusting the work, and clearing away the superfluous gold. Oil Gilding. Prime the work first with boiled linseed oil and white-lead; when dry, do it over with a thin coat of gold size, consisting of stone-ochre ground in fat-oil. When that is so dry as to feel clammy, it is fit for gilding. Spread the Heaves of gold upon the cushion, cut them into slips of the pro- per width for covering the work, breathe upon the tip, as by moistening it thus, it will take up the leaves from the cushion. Apply them by the tip on the proper parts of the work, and press them down by the ball of cotton. Repair, by putting small pieces of gold on any parts which you have omitted to cover. When the work is covered, let it dry, and then clear it off with the brush. This sort of gilding, the easiest and least expensive, will stand the weather, and may at any time be cleaned with a little water. Burnished Gilding is the sort of gilding generally used for picture-frames, looking-glasses, &c. The wood intended to be gilt in this manner, should first be sized, then done over, with eight coats of size and whiting, to cover it with a body of con- siderable thickness. Having laid a sufficient quantity of whit- ing upon the work, it must be cleaned off, freeing all the cavi- ties and hollows from the whiting that may have choked them up, and by proper moulds and tools, restoring the sharp- ness of the mouldings. It then receives a coat of size, made by boiling Armenian bole with parchment size. As this must not remain till it is quite dry, it is prudent not to lay on more at a time than can be gilt before it becomes too dry. The work being thus prepared, place it a little declining from you, and with clean water and a hair pencil moisten a part of it, apply the gold by the tip to the moistened part, it will imme- diately adhere to the work: proceed to wet the next part, and apply the gold as before, repeating this operation till the whole is completed; let not any drops of water come upon the gold already laid on, therefore no part should be missed in going over it at first, since it is not so easily mended as oil gilding. The work being thus gilt, remains twenty-four hours; when the parts designed to be burnished are polished with a dog's tooth, or an agate burnisher, but the gilding must not be quite dry when it is burnished. Japanner's Gilding. To gild japanned work, we draw with a hair pencil, in gold size, the intended ornaments, and after- wards apply gold leaf or gold powder. The gold size is pre- pared thus: take of linseed-oil, and of gum-animi, four ounces. Boil the oil, add the gum-animi gradually in powder, stirring each quantity in the oil till it be dissolved, then put in another, till the whole be mixed. Let the mixture boil till it acquire a thicker consistence than tar; strain the whole through a coarse cloth, and keep it for use; when applied, it must be mixed with , , e. the seed then lay some gold leaf on it in the usual way. vermilion and oil of turpentine. Having laid on the gold size, and allowed it to dry, the gold leaf is applied in the usual way, or if it is not wanted to shine so much, gold powder is applied, which is made by grinding gold leaf upon a stone with honey, and afterwards washing the honey away with water. If the gilding is varnished, Dutch gold may be used, instead of real gold powder, or aurum musivum may be used. To Write on Paper with Letters of Gold. Put gum-arabic into writing ink, and write in the usual way. When the writ- ing is dry, breathe on it; the warmth and moisture will soften the gum, and cause it to fasten on the gold leaf, which may be laid on in the usual way, and the superfluous part burnished off. Or, instead of this use japanner's size. - To lay Gold upon White Earthenware, or Glass. Draw the design upon the vessel to be gilt with japanner's gold size, moistening it if necessary with oil of turpentine. Set the work in a room free from dust, to dry, for an hour, then place it so near the fire that you could just bear the heat of it with your hand for a few seconds. Let it remain there till it feels clammy, Then put the ware into an oven to be baked for about three hours. Glasses, &c. are gilt by drawing the figures with shell gold mixed with gum-arabic and borax. Then apply sufficient heat to it, and lastly burnish it. - - . . . . To Gild on Glass or Porcelain, by Burning-in. Dissolve gold in aqua-regia, evaporate the acid by heat, and you will obtain a gold powder; or precipitate the gold from the solution by pieces of copper. Lay this gold on with a strong solution of borax and gum water, and it may be burned-in. - To Gild Metals. One method of applying gold upon metals is by first cleaning the metal to be gilt; gold leaf is then laid on it. This rubbed with a polished blood stone, and a certain degree of heat, adheres perfectly well. In this manner silver leaf is fixed and burnished upon brass, in the making of what is called French Plate ; and sometimes gold leaf also is bur- nished upon copper and iron. . Gilding by Amalgamation is by previously forming the gold into a paste, or amalgam, with mercury. But to obtain an amalgam of gold and mercury, the gold is reduced into thin plates or grains, heated red-hot, and thrown into mercury pre- viously heated, till it begins to smoke. Upon stirring the mercury with an iron rod, the gold totally disappears. The proportion of mercury to gold is generally as six or eight to one. The method of gilding by amalgamation, is chiefly used for gilding copper, or an alloy of copper, with a small portion of zinc, which receives the amalgam more readily, and is pre- ferable on account of its colour, resembling that of gold more than the colour of copper. When the metal to be gilt is wrought or chased, it is previously covered with quicksilver before the amalgam is applied, that this may spread easier; but when the surface of the metal is plane, the amalgam may be applied to it directly. The metal to be gilt is first rubbed with aqua-fortis, which cleans the surface from any rust or tarnish that might prevent the union of the metals. The amal- gam is then spread equally over the surface by a brush, and the mercury is evaporated by heat sufficient for that purpose; if the heat be too great, part of the gold also may be expelled, and part of it will run together, and leave some of the surface of the metal bare. While the mercury is evaporating, the work is from time to time taken from the fire, and examined, that the amalgam may be spread more equally by means of a brush; and any defective parts again covered, and that the heat may not be too suddenly applied. When the mercury has evaporated, which is known by the surface becoming entil ely of a dull colour, the metal then undergoes other operations, by which it receives the fine gold colour. First, the gilded piece of metal is rubbed with a scratch-brush (a brush made of brass wire,) till its surface is quite smooth; it is then covered with gilding war, and again exposed to the fire till the wax be burnt off. This wax is composed of bees-wax, mixed with either red ochre, verdigris, copper scales, alum, vitriol, or borax ; but the saline substances are sufficient without any wax. The colour of the gilding is heightened by this operation. The gilt surface is then covered with a saline composition of nitre, alum, or other vitriolic salt, ground together, and mixed into a paste with water and urine. The metal thus covered is exposed to a 5 G G I L G. I. A IºTION: ARY OF 'º6HANICAL SCI ENGE. certain degree of heat, and then quenched in water. By this method its colour is further improved, and brought nearer to that of gold. This effect seems to be produced by the acid of nitre (which is disengaged by the sulphuric acid of the alum, during the exposure to heat) acting upon any particles of cop- per which may happen to lie upon the gilded surface. Lastly, some artists think that they give an additional lustre to their gilt work, by dipping it in a liquor prepared by boiling some yellow materials, as sulphur, orpiment, or turmeric. The only advantage of this operation is, that part of the yellow matter remains in some of the hollows of the carved work, in which the gilding is apt to be more imperfect, and to which it gives a rich and solid appearance. - * - Gilding Iron or Steel. In gilding iron or steel by means of an amalgam, as the metal has no affinity for the mercury, an agent is employed to dispose the surface to receive the gilding. This agent is, a solution of mercury in nitrous acid (aqua for- tis,) or what workmen call quicksilver water, applied to the parts to be gilded; the acid, by a stronger affinity, seizes on a portion of the iron, and deposits in its place a thin coating of mercury, which will not refuse a union afterwards with the gold amalgam that may be applied; by this process, the nitrous acid.injures the surface of the metal, and the union of the mer- cury being very slight, a bright and durable gilding cannot be obtained. . - . . . Another Method. Apply a solution of blue vitriol with a camel's-hair pencil, to the parts of the steel to be gilt, and by a chemical action, similar to that we described as taking place when a solution of nitrate of mercury is employed, a thin coat- ing of copper is precipitated on the metal. The copper has an affinity for mercury, and a union is thus effected between the amalgam and the iron or steel. But the surface is injured by the action of the acid employed, and still a heat sufficient to volatilize the mercury must be afterwards used. . . . Gilding of Iron by Heat. When the surface has been polished bright, it is heated till it becomes blue. Gold leaf is then applied, and burnished down. It is then heated again, another layer of gold burnished on it, and in this manner three or four coats are given, according to the intended strength of the gilding. This, though a more laborious process than the two last, is not attended with so much risk. An Improved Process for Gilding Iron or Steel. This process, less known among artists than it deserves to be, cannot fail to be useful to those who gild iron or steel. process consists in pouring over a solution of gold in nitro- muriatic acid (aqua-regia) about twice as much ether. must be done with caution, and in a large vessel. These liquids are then shaken together, and as soon as the mixture is at rest, the ether will be seen separating itself from the nitro-muriatic acid, and floating. on the surface. The nitro-muriatic acid becomes more transparent, and the ether darker, than they were before ; because the ether has taken the gold from the acid. The whole mixture is then poured into a glass funnel with a small aperture, which must not be opened till the fluids have separated themselves from each other. lowest place by its greater gravity; the aperture is then shut, and the funnel will be found to contain nothing but ether mixed with gold. This is preserved for use in bottles well closed. In order to gild iron or steel, the metal is first well polished with emery, or the finest crocus martis, or colcothar of vitriol, and common brandy. The auriferous ether is then applied with a small brush; the ether soon evaporates, and the gold remains on the surface of the metal. The metal may then be put into the fire, and afterwards polished. By means of this auriferous ether, figures of all kinds may be delineated on iron, by a pen or fine brush. Instead of ether, the essential oils of turpentine or lavender may be used which will also take gold from its solution. Cold Gilding of Silver. Dissolve gold in nitro-muriatic acid, dip some linen rags in the solution, then burn them, and pre- serve the ashes. Whatever is to be gilded must be previously well burnished : a piece of cork is then dipped, first into a solution of salt and water, and afterwards into the black pow- der, and the piece being rubbed with it must be burnished. Gilding Copper or Brass is thus done: evaporate a saturated The first part of the This It is then opened, and the nitro-muriatic acid will run off, it having taken off the solution of gold to the consistence of:oil, let it shoot into crys- tals, which dissolve in pure water, immerse in this the articles to be gilded, wash them afterwards in pure water, and burnish them. - Grecian Gilding. Dissolve mercury in muriatic acid, (spirits , of salt,) which will give a muriate of mercury. Equal parts of this and sal ammoniac are then mixed, and dissolved in aqua- fortis. Put some gold into this, and it will dissolve. This applied to silver, becomes black; but by heating, it assumes the appearance of gilding. . - To make Shell. Gold. Grind, in a mortar, gold leaf and homey, then wash away the honey with water, and mix the gold powder with gum water. This may be applied to any article with a camel's-hair pencil, in the same way as any other colour. - - GIMBALS, the brass rings by which a sea-compass is sus- pended in its box, so as to counteract the effect of the ship's motion, and keep the card horizontal. GIMBLETING, a term applied to the anchor, to denote the action of turning it round by the stock, so that the motion of the stock appears similar to that of the handle of a gimblet when it is employed to turn the wire. . GIN, in Mechanics, a machine for driving piles, fitted with a windlass and winch at each end, where eight or nine men heave, and round which a rope is reeved that goes over the wheel at the top; one end of this rope is seized to an iron monkey that hooks to a beetle, of different weights, according to the piles that are to be driven, being from 8 to 13 hundred weight; and when hove up to a cross piece, near the wheel, it unhooks the monkey, and lets the beetle fall on the upper end of the pile, and thereby forces the same into the ground; then the monkey’s own weight overhauls the windlass, in order for its being hooked again to the beetle. See PILE Engine. GIRT, the situation of a ship which is moored so tight by her cables, extending from the hawse to two distant anchors, as to be prevented from swinging or turning about according to any change of the wind or tide, to the current of which her head would otherwise be directed. The cables are extended in this manner by a strong application of mechanical powers within the ship; so that, as she veers or endeavours to swing about, her side bears upon one of the cables, which catches on her heel, and interrupts her in the act of traversing. In this position she must ride, with her broadside or stern to the wind or current, till one or both of the cables are slackened so as to sink under the keel; after which, the ship will readily, yield to the effort of the wind or current, and turn her head thither. - GIRT Line, a rope passing through a single block on the head of the lower masts, to hoist up the rigging thereof, and the persons employed to place the rigging and cross-trees on the mast-heads; the girt-line is, therefore, the first rope em- ployed to rig a ship, after which it is removed till the ship is to be unrigged. * k GIVEN, is a term frequently used by mathématicians, to denote something supposed to be known. Thus, if a magni- tude be known, it is said to be a given magnitude. If the posi- tion of a thing be known, it is given in position; thus, if a circle be described with a known radius, its centre is given in position, and its circumference given in magnitude, and the circle itself is said to be given both in magnitude and position. If the kind or species of a figure be known, it is said to be given in species; if the ratio between two quantities be known, these quantities are said to have a given ratio, &c. &c. GIVE WAY, is the order to a boat’s crew to row after having ceased for a short time, or to increase their exertions if they were before rowing. Give way together, implies that men should keep time together in rowing, so as that the oars should all dip and rise together, whereby their several forces are exerted as one. GLACIS, in Fortification, the mass of earth which serves as a parapet to the covered way, sloping easily towards the champaign field. In Building, glacis expresses any declivity, which is less steep than the slope called Talus . In Gardening, a descent sometimes begins in a Talus, and ends in a glacis. . . GLAIR. Eggs, is the same as the white of eggs, used as a warnish for preserving paintings. For this purpose, it is beat I, A S S M \,\ | F.A ("T" || R.E. /* / ºnly /*/º/m/ /* * (asanº. G. L. A G. L. A 391 DICTIONARY OF MECHANICAL SCIENCE. to an unctuous consistence, and commonly mixed with a little brandy or spirits of wine, to make it work more freely, and I with a little lump-sugar to give it body and prevent it crack- ing, and then spread over the picture with a fine elastie brush. GLASS, a transparent, brittle metal, made of sand-melted in a strong fire with fixed alkaline salts, lead, slags, &c. till the whoke becomes perfectly clear. and fine, ... And: the manu- factured glass may be divided into three kinds—white trans- parent glass, coloured glass, and common green or bottle glass. Of the first of these, there are many different kinds, as flint glass, crystal, mirror plate, window glass, &c. Of the coloured glass, there is also a great variety, resulting from accidental combinations or preparations. - Accident is said to have discovered the constituent parts of glass. Some merchants, with a freight of soda, cast anchor at t the mouth of the river Belus, in Phenicia, and were dressing their dinner on the sand, using large lumps of the soda as sup– ports for their kettles. The fire melting the soda, and the siliceous earth together, exhibited-glass. A manufacture was instantly established, and to this place it was for a long time confined. What was the soda previously used for? Glass was made in great perfection among the ancients; as drinking glasses, prisms, and coloured glasses of various kinds. It was known to the Romans, but was by no means common among them, for Nero paid £50,000 for two glass cups. Glass was first used for windows in, the third century. Glass, as we have remarked, is a solid, transparent, brittle, substance, produced by melting together sand, flint, and alka- | There, are other saline matters employed in the line salts. manufacture of glass, as poeverine, or rochetta, which is pre- pared from glass wort or salsola kali, an indigenous plant, : but which is chfefly imported from Spain; where it is cut down in the summer, dried in the sun, and burned in heaps, when the ashes fall into a pit, where they concrete into a hard mass. A similar salt is obtained from the ashes (kelp) of the common sea-wrack. The sand used in the manufacture of glass is found at Lynn in Norfolk, Maidstone in Kent, &c. &c. The following are the processes employed in making glass: Fritting. after extracting all the impurities, are conveyed to the furnace in pots made of tobacco-pipe clay. The produce of this pro- cess is called the frit, which is again melted in large pots or crucibles, till: the whale, mass becomes. the dross rises to the top. Blowing, (see Plate, fig. beautifully clear, and 1,) is the next process, which in round glass, as phials, drinking glasses, &c. is thus performed. The workmen dip the end of long iron pipes, red-hot, into the liquid glass, then roll it on a polished irón plate to give it an external even surface; they next blow down the iron pipe till it enlarges the metal like a bladder, and, if necessary, roll it again on the iron plate, and proceed to form it into a globular, or any other required. The glass is then transferred from the blowing pipe, by dipping the end of another iron rod into the liquid glass, which adheres to the heated rod, aud with which the workman sticks it to the bottom of the vessel; then with a . pair of pincers, wetted with water, he touches the neck, which immediately cracks, and on being slightly struck, separates at the end of the blowing pipe, and becomes attached to the iron : rod. The vessel is next carried up to the mouth of the furnace to be heated and softened, that the operator may finishit. If the vessel require a handle, the operator forms it separately, and unites it while melting-hot, forming it with pincers to the requisite shape and pattern. blown, or cast, into a furnace, whose heat is not sufficiently intense to melt it; and gradually withdrawing the article from : the hottest to a cooler part of the annealing chamber, till it is cold enough to be taken out for use. a state of fusion. . . . . . . . . . . . . Blue, glass is formed by the oxyde of cobalt; in Green, by the oxyde of iron or coppér; ‘’’ Violet, by the oxyde of manganese; * Red, by a mixture of the oxydes of copper and iron; Purple, by the sxyde of gold; - | melted in about 24 hours. | polished, and foliated. White, by the oxyde of arsenic and zinc ; - Yellow, by the oxyde of silver, and by combustible bodies; And Black, from a mixture of oxyde of manganese, cobalt, ... in this manner is made those elegant pastes, which so faith- fully imitate, and not unfrequently excel, in brilliance, their originals, the gems of antiquity. The glass, however, for this purpose, is prepared in a peculiar manner, and requires great nicety. It combines purity and durability. Opaque glass is made by the addition of the oxyde of tin, and produces that beautiful imitation of enamel which is so much admired. Dials for watches and clocks are made in this manner, and are manu- | factured “exclusively at the Falcon Glass-house, Surrey side of Blackfriars' Bridge. } Cutting or Ornamenting, is effected by a machine, in which there is a large wheel turned by a winch. The band of this wheel passes round a pulley on the axle of a wheel or cutter, which it turns with great velocity. Beneath the cutter a cistern is placed, and above it a small cask containing water, the cock of which is so placed, as to drop very slowly on the circum- ference of the cutter. The operator, after dressing the edge of the cutter with emery paste, applies successively the parts of the glass which are to be cut, and dexterously moves it as the parts are sufficiently ground away. The principal sorts of glass are, crown glass. The best win- | dow glass is made of white sand, purified barilla, saltpetre, borax, and arsenic, melted together; and if the glass assume a yellowish hue, the defect is removed by adding a sufficient quantity of manganese. - * - Newcastle glass, generally used in England, is of an ash colour, frequently speckled, streaked, and blemished. It is made from white sand, umpurified barilla, common salt, arsenic, and manganese. - The bottle or green glass, usually made of common sand, iſ lime, and some clay fused with an impure alkali, is very hard, and resists the corrosive action of all liquids much better than | flint glass; the green colour is owing to the iron: it is well # adapted for chemical vessels. r The various materials are carefully washed, and - Elint glass, the most fusible of any, is used for bottles, uten- sils intended to be cut and polished, and for various ornamental purposes. The best kind is composed of white siliceous sand, pearl ash, red oxyde of lead, nitrate of potash, and the black Oxyde of manganese. . . . - . . . . ... Plate glass, so called from its being cast in plates or large sheets, is the most valuable, and is employed for mirrors and the windows of carriages. It is composed of white sand cleansed with purified pearl ashes and borax. ... But should the metal appear yellow, it is restored to its pellucid transparency by the addition (in equal proportions) of a small quantity of manganese and arsenic. It is, cast on a Harge horizontal table, and all excrescences pressed out by passing a large roller over the metal. To polish the glass, it is laid on a large horizontal table of freestone perfectly smooth; and then a smaller piece of glass, fastened to a plank of wood, is passed over the other till it has received its due degree of polish. But to facilitate this process, water and sand are used as in the . . . Polishing of marble; and, lastly, Tripoli stone, smalt, and emery, to give it lustre. . . . . We must go a little more into the detail of this art. Fig. 2 represents the casting furnace with its melting pot, &c. A is is the bocca, or mouth of the furnace; B the cistern that con- veys the liquid glass out of the melting pots in the furnace to | the casting table D. This cistern is brought out of the furnace Annealing is the removing of the glass after it has been 'by means of the iron chain suspended on the hook over the bocca. The cistern thus placed on its carriage, and moved. over the table, the bottom, which is moveable, is slipped off the torrent of liquid flaming matter, and flows over the surface of the ... - - - * | table, where it is ruled to its proper thickness and dimension Colouring. The different coloured glasses owe their tints to the different metallic oxydes mixed with the materials while by the rulers EE, and the roller F in the workman's hands. The cisterns remain six hours in the furnace; the metal is The glass is now to be ground, Grinding and Polishing, fig. 3, gives plate glass a fine lustre. | The grinder takes it rough out of the hands of the caster, and | laying it upon a stone table, to which it is fixed with stucco, he | lays another rough glass, half the size of the former, upon it. 392 G. L. O G L A DICTIONARY OF MECHANICAL SCIENCE, To the smaller glass a plank is fastened by means of stucco, and to the whole a wheel B, made of hard light wood, about sixiàches in diameter, by pulling of which from side to side, and from end to end of the glass, a constant attrition is kept up; and by allowing water and fine sand to pass between the wº plates, the whole is very finely polished; but to give the finish- ing pºlish; powder of smalt is used. As the upper glass grows smººtherit is taken away and a rougher one substituted in its stead; and so on till the work is done. Except in the very largest platés; the workmen polish their glass by means of a plank having four wooden handles to move it; and to this plank a plate of glass is cemented, as above. Achromatic Flint GLAss. The important discovery of M. Guinaud in the manufacture of flint glass for large telescopes, shall close our article upon Glass. The excise laws of Eng- land have prevented our artists from attempting to melt glass on a proper scale for making lenses for achromatic telescopes; but in France, where no such restrictions exist, numerous attempts have been made to perfect the manufacture of flint glass for optical purposes; and M. Guinaud's labours have been finally crowned with complete success. The almost total impossibility of procuring flint glass exempt from striae, sug. gested to this artist the construction of a furnace capable of melting two hundred weight of glass in one mass, which he såwed vertically, and polished one of the sections, in order to observe what had taken place during fusion. He discovered his metal to be vitiated by striae, specks or grains with cometic tails, and from time to time as he obtained blocks including portions of good glass, his practice was to separate them by sawing the blocks into horizontal sections, or perpendicular to their axis. A fortunate accident conducted him to a better process. While his men were one day carrying a block of this glass on a hand-barrow to a saw-mill which he had erected at the fall of the Doubs, the mass slipped from its bearers, and rolling to the bottom of a steep and rocky declivity, was broken to pieces. M. Guinaud was at first grieved at this misfortune, but having selected those fragments which appeared perfectly homogeneous, he softened them in circular moulds, in such a manner, that on cooling he obtained disks that were after- wards fit for working. To this method he adhered, and con- trived a way of clearing his glass while cooling, so that the fractures should follow the most faulty parts. When flaws occur in the large masses, he removes them by cleaving the pieces with wedges; he then melts them again in moulds, which give them the form of disks, taking care to allow a little of the glass to project beyond one of the points of the edge, so that the optician may be enabled to use that portion of glass in making a prism, which shall give the measure of the index of refraction, and thus obviate the necessity of cutting the lens. The Astronomieal Society of London have tried disks of M. Guinaud's flint achromatic glass, which seems entirely homo- geneous, and exempt from fault. This material, Mr. Tully, a very able optician in London, considers different from our English flint glass, as it grinds and polishes much easier. GLAss, the usual appellation for a telescope. Night-Glass, a telescope made for viewing objects at night. Half-hour-GLAss, frequently called the Watch-Glass, is used to measure the time which each watch has to stay upon deck. Half-minute and Quarter-minute-Glasses, are used to ascertain the rate of a ship’s velocity, measured by the log; these glasses should be frequently compared with a good stop watch, to determine exactly how many seconds they run. Sweat the Glass, is to turn it before the sand has quite run out, and thereby gaining a few minutes in each half hour, make the watch too short. Glass is used in the plural, to denote the duration of any action; as, they fought yard-arm and yard-arm three glasses, i. e. three half-hours, or an hour and a half. GLAUCOMA, in Surgery, a disease in the eye, by which the crystalline humour turns bluish, and its transparency diminish- es, so that all objects appear to the patient as through a cloud or mist; but when the disorder has reached its height, the visual rays are all intercepted, and blindness follows, espe- gially in aged persons. The applications are those used internally in the gutta serena. - GLAZIER'S VIce, a machine for drawing window lead, and may be thus described. P G, Q H, are two axles, running . To Flog or in the frame KL, ML, CD, are two wheels of iron, case- hardened, 13 inch broad, and of the thickness of a pane of glass; these wheels are fixed to the axles, and run very near one another, their distance not exceeding ºf an inch: across their edges several nicks are cut, the better, to draw the lead through. E, F, are two pinions, each of twelve leaves, turning one another, and going upon the ends of the axles, which are square, being kept fast there by the nuts P Q, which are screwed fast with a key. A B, are two cheeks of iron, case- hardened, and fixed on each side to the case with screws; these are cut with an opening where the two wheels meet, and set, so near to the wheels as to leave a space equal to the thickness of ... ſ. H - Z % #4% * , º/, 2--> --> º yº the lead ; so that between the wheels and the cheeks there is left a hole of the form represented at N, which is the shape of the lead when cut through. The frame KL M L is held toge- ther by cross bars passing through the sides, and screwed on ; and a cover is put over the machine to exclude the dust. The whole is screwed down fast to a bench by screw nails L. L. When the vice is used, the lead to be drawn is first cast in moulds, into pieces a foot long, with a gutter on each side. One of these pieces is taken, and an end of it sharpened a little with a knife ; then, being put into the hole between the wheels, by turning the handle I the lead is drawn through the vice, and receives the form designed. w GLOBE, in Geometry, a round solid body, which may be conceived to be generated by the revolution of a semicircle about its diameter. See SPHERE. . A - Globe, or Artificial Globe, in Geography and Astronomy, is more particularly used to denote a globe of metal, plaster, paper, pasteboard, &c.; on the surface of which is drawn a map, or representation of either the heavens or the earth, with the several circles which are conceived upon them : the former being called the Terrestrial Globe, and the latter the Celestial Globe. The TeRRestri Al Globe. (See Plate.)—The terrestrial globe is an artificial representation of the earth, which we have already described. The diurnal motion of this globe is from West to east. THE CELESTIAL Globe is an inverted representation of the heavens, on which the stars are marked according to their several situations. The diurnal motion of this globe is from east to west, to represent the apparent diurnal motion of the sun and stars. The eye is supposed to be placed in the centre of this globe, but in fact it is beyond the stars. . . * The Axis of the earth, fig. 2, is an imaginary line A B passing through its centre; and the wire on which the artificial globe turns represents this line. 3. - The Poles of the earth are the extremities of this axis; that on the north is called the Arctic, that on the south the Antarctic pole. The celestial poles are imaginary points in the heavens, exactly above the terrestrial poles. * The brazen Meridian, A E, fig. 6, the circle in which the artifi- cial globe turns; divided into 360 degrees. Every circle is sup- posed to be divided into 360 equal parts, called degrees, each degree into sixty equal parts called minutes, each minute into sixty equal parts called seconds, &c.; a degree is therefore only a relative idea, and not an absolute quantity, except when ARTIFICIAL, GLOBE, S - ("E L E S TIAL AND TERRIES TRIAL, * * tº ºwe ºp/ere. frºmiſſary ºphºre. º Mººr. -ſ /*ara/e/ ºphere. Mºle ºr - Barris London. Terrararºa/ tºo/*e. . - - - - _º // o a - º - a - sº % º - % Zºrrºw ºoſe ºwnºmazzº Prºjection of a dºe to warfare the yearanº &c. for coverinº, a tºo/*. - him - iii. mº" mº -º- - ºn The method of drºw (* or Covering for a tºo/*e. * * * * * * * * * * * * - - - - -- -- - *- - - - - mº" - *m. - - ºrſ tºº. ºned tº ºr sº ºn ºn May 15-6 tº L. O. G. L. O DICTIONARY OF MECHANICAL SCIENCE. 393 applied to a great circle of the earth, as to the equator or to a | meridian, in which cases it is sixty geographical miles, or 69% English miles. A degree of a great circle in the heavens is a space nearly equal to twice the apparent diameter of the sun; or to twice that of the moon when considerably elevated above the horizon. Degrees are marked with a small cipher, minutes with one dash, seconds with two, thirds with three, &c. Thus, 25° 14'22' 35", are read 25 degrees, 14 minutes, 22 seconds, 35 thirds. - . . ' In the upper semicircle of the brass meridian, fig. 6, these degrees are numbered 10, 20, &c. to 90, from the equator towards the poles, and are used for finding the latitudes of places. and are used in the elevation of the poles. - Great Circles, as the equator, ecliptic, and the colures, divide the globe into two equal parts. See fig. 2. Small Circles, as the tropics, polar circles, parallels of lati- tude, &c. divide the globe into two unequal parts. Fig. 2. Meridians, or lines of longitude, are semicircles, extending from the north to the south pole, and cutting the equator at right angles. Every place upon the globe is supposed to have a meridian passing through it, though there be only twenty- four drawn upon the terrestrial globe; the deficiency is sup- plied by the brass meridian. . When the sun comes to the meridian of any place (not within the polar circles) it is noon or mid-day at that place. Figs. 3, 4, and 5. f The First Meridian is that from which geographers begin to reckon the longitudes of places. In English maps and globes the first meridian is a semicircle supposed to pass through London, or the royal observatory at Greenwich. The Equator, a great circle of the earth, equidistant from the poles, divides the globe into two hemispheres, northern and southern. The latitudes of places are reckoned from the equa- tor, northward and southward, and the longitudes are reckoned upon it eastward and westward. The equator, when referred to the heavens, is called the equinoctial, because when the sun appears in it, the days and nights are equal all over the world, viz. twelve hours each. The declination of the sun, stars, and planets, are counted from the equinoctial northward and south- ward; and their right ascensions are reckoned upon it east- ward round the celestial globe from 0 to 360 degrees. Fig. 5. The Ecliptic is a great circle in which the sun makes his apparent annual progress among the fixed stars. It is the real path of the earth round the sun. . The intersection at 23° 28′ is called the equinoctial points; the ecliptic is situated in the middle of the zodiac. The apparent path of the sun is either in the equinoctial or in lines nearly parallel to it, and his apparent annual path may be traced in the heavens, by observ- ing what particular constellation in the zodiac is on the meri- dian at midnight; the opposite constellation will shew, very nearly, the sun's place at noon on the same day. Figs. 1 and 2. The Zodiac on the celestial globe is a space which extends about 8° on either side of the ecliptic. Within this belt the motions of the planets are performed. Fig. 1. - - Signs of the Zodiac. The ecliptic and zodiac are divided into twelve equal parts, called signs, each containing 300; and the sun makes his apparent annual progress through the ecliptic at the rate of nearly a degree in a day. The names of the signs, and the days on which the sun enters them, are as follow : 'SPRING SIGNS. SUMMER SIGNS. on Aries, the Ram, 21st of gº Cancer, the Crab, 21st of March. - June. 8 Taurus, the Bull, 19th of Su Leo, the Lion, 22d of April. r July. - II Gemini, the Twins, 20th of my Virgo, the Virgin, 22d of May. º * August. All northward of the equator. ... AUTUMNAL SIGNs. wiNTER sig Ns. * Libra, the Balance, 23d of w? Capricornus, the Goat, 21st September. of December. m Scorpio, the Scorpion, 23d ::: Aquarius, the Waterbearer, of October. | 20th of January. t Sagittarius, the Archer, 22d × Pisces, the Fishes, 19th of of November. ~. I February. These are called southern signs, being all south of the equator. On the lower semicircle of the brass meridian they are numbered 10, 20, &c. to 90 from the poles towards the equator, The Colures, two great circles passing through the points Aries and Libra, and the poles of the world; Cancer and Ca. pricorn, and the poles of the world, have their uses in mecha- nical geography. That passing through Aries and Libra, is called the equinoctial colure; that passing through Cancer and Capricorn, the solstitial colure. Fig. 1. - Ae The Tropics are two smaller circles, each 23° 28′ from the equator, with which they are parallel ; the northérn is called the Tropic of Cancer, the southern the Tropic of Capricorn. The tropics are the limits of the torrid zone, northward and southward; and within these boundaries alone is the sun ever Figs. 1 and 2. ' . . seen vertical. The Polar Circles are two small circles, parallel to the equa- tor' (or equinoctial), at the distance of 66° 32' from it, and 23° 28′ from the poles. The northern is called the Arctic, the southern the Antaretic circle. Figs. 1 and 2. “ Parallels of Latitude are small circles drawn through every ten degrees of latitude, on the terrestrial globe, parallel to the equator. Every place on the globe is supposed to have a parallel of latitude drawn through it, though there are generally only 16 parallels of latitude drawn on the terrestrial globe. The Hour Circle on the artificial globes is a small circle of brass, with an index or pointer fixed to the north pole. The hour. circle is divided into twenty-four equal parts, correspondi ing to the hours of the day; and these are again subdivided into halves and quarters. Figs. 6 and 7. The Horizon is a great circle which separates the visible half of the heavens from the invisible; the earth being consi. dered as a point in the centre of the sphere of the fixed stars. Horizon, when applied to the earth, is either sensible or rational. Figs. 1, 2, 6, and 7. The Sensible, or Visible Horizon, is the circle which bounds our view, where the sky appears to touch the earth or sea. The sensible horizon extends only a few miles; for example, if a man of six feet high were to stand on a large plane, or on the surface of the sea; the utmost extent of his view, upon the earth or the sea, would be only a very few miles. The Rational, or true Horizon, is an imaginary plane, pass- ing through the centre of the earth parallel to the sensible horizon. It determines the rising and setting of the sun, stars, and planets. Figs. 1 and 2. e The Wooden Horizon, B C, circumscribing the artificial globe, represents the rational horizon on the Earth. This hori- zon is divided into several concentric circles, arranged in the following order: One contains the thirty-two points of the compass, divided into half and quarter points. The degrees in each point are to be found in the amplitude circle. Another contains the twelve signs of the zodiac, with the figure and character of each sign; and another contains the days of the month answering to each. degree of the sun's place in the ecliptic, and the twelve calendar months. . . . g The Cardinal Points of the horizon are east, west, north, and south. The Cardinal Points in the heavens are the zenith, the nadir, and the points where the sun rises and sets. . The Car- dinal Points of the ecliptic are the équinoctial and solstitial points, which mark out the four seasons of the year; and the cardinal signs are— • * on Aries, as Cancer, a Libra, and ºf Capricorn. The Zenith is a point in the heavens exactly over head, and is the elevated pole of our horizon. Fig. 2. The Nadir is a point in the heavens exactly under our feet, being the depressed pole of our horizon, and the zenith, or ele- wated pole, of the horizon of our antipodes. Fig. 2. . The Polé of any circle is a point on the surface of the globe, ninety degrees distant from every part of the circle of which it is the pole. Thus the poles of the world are ninety degrees from every part of the equator; the poles of the ecliptiº (on the celestial globe) are ninety degrees from every part of the echip- tic, and 33° 28′ from the poles of the equinoctial, consequently they are situated in the arctic and antarctic circles. Every circle on the globe, whether real or imaginary, has two polés diametrically opposite to each other. Figs. I and 2. - The Equinoctial Points are Aries and, Libra, where the ecliptic cuts the equinoctial. The point Aries is called the vernal equinox, and the point Libra the autumnal equinox, º 5 H 394 G L O G. L. O. . DICTIONARY OF MECHANICAL SCIENCE. When the sun is in either of these points, the days and nights on every part of the globe are equal to each other. The Solstitial Points are Cancer and Capricorn. When the sun enters Cancer, it is the longest day to all the inhabitants on the north side of the equator, and the shortest day to those on the south side. When the sun enters Capricorn, it is the shortest day to those who live in north latitude, and the longest day to those who live in south latitude. - An Hemisphere is half the surface of the globe; for every great circle divides the globe into two hemispheres. The horizon divides the upper from the lower hemisphere in the heavens; the equator separates the northern from the southern on the earth; and the brass meridian, standing over any place on the terrestrial globe, divides the eastern from the western hemisphere. See figs. 2, 3, 4, and 5. - The Mariner's Compass is a representation of the horizon, and by seamen it is used to direct and ascertain the course of their ships. It consists of a circular brass box, which contains a paper card, divided into thirty-two equal parts, and fixed on a magnetical needle that always turns towards the north. . Each point of the compass contains 11° 15', or 113 degrees, being the 32d part of 360 degrees. See CoMPAss. . The Variation of the Compass is the deviation of its points from the corresponding points in the heavens. When the, north point of the compass is to the east of the true north point of the horizon, the variation is east; if it be to the west, the variation is west. The compass is used for setting the artificial globe north and south; but care must be taken to make a proper allowance for the variation. * . The Latitude of a place, on the terrestrial globe, is its dis- tance from the equator in degrees, minutes, or geographical miles, &c. and is reckoned on the brass meridian, from the equator towards the north or south pole. See LATITUDE. The Quadrant of Altitude, E, fig. 6, a thin piece of brass divided upwards from 0 to 90 degrees, downwards from 0 to 18 degrees; when used, it is generally screwed to the brass Meridian. The upper divisions determine the distances of places on the earth, the distances of the celestial bodies, their latitudes, &c.; and the lower divisions are applied to finding the beginning, the end, and duration of twilight. - The Longitude of a place on the terrestrial globe, is the dis- tance of the meridian of that place from the first meridian, reckoned in degrees, and parts of a degree, on the equator. Longitude is either eastward or westward, according as a place is to the east or west of the first meridjan. No place can have more than 180 degrees, or half the circumference of the globe. See LoNGITUde. s Hour Circles, are the the same as meridians. They are drawn through every fifteen degrees of the equator, each answering to an hour. The brass meridian and these circles always correspond. A Parallel Sphere, fig. 4, is represented truly when the equator and rational horizon correspond. The poles are perpendicular to the horizon. A Direct or Right Sphere, fig. 5, is the reverse; the equator is at right angles with the horizon. An Oblique Sphere, fig. 3, is that position the earth has when the rational horizon cuts the equator obliquely, and hence it derives its name. All inhabitants on the earth (except those who live exactly at the poles, or at the equator) have this position of the sphere. The days and nights are of unequal lengths, the parallels of latitude being divided into unequal parts by the horizon. Climate, is a part of the surface of the earth contained between two small circles parallel to the equator, and of such a breadth, that the longest day in the parallel nearest the pole, exceeds the longest day in the parallel of latitude nearest the *quator, by half an hour, in the torrid and temperate zones, or by a month in the frigid zones; so that there are twenty-four climates between the equator and each polar circle, and six climates between each polar circle and its pole. A Zone, is a portion of the earth's surface contained between any two circles parallel to the equator; and there are five zones. . The Torrid Zone, extending from the tropic of Cancer to the tropic of Capricorn, is 46° 56' broad. This zone was thought by the ancients to be uninhabited, because it is con- tinually exposed to the direct rays of the sun; and such parts of the torrid zone as were known to them were sandy deserts, as the middle of Africa, Arabia, &c. and these sandy deserts extended beyond the left bank of the Indus, towards Agimere. The Two Temperate Zones. The north temperate zone extends from the tropic of Cancer to the arctic circle; and the south temperate zone from the tropic of Capricorn to the antarctic circle. These zones are each 43°4' broad, and were called temperate by the ancients, because meeting the sun's rays obliquely, they enjoy a moderate degree of heat. The Two Frigid Zones. The north frigid zone, or rather segment of the sphere, is bounded by the arctic circle. The north pole, which is 23° 28′ from the arctic circle, is situated in the centre of this zone. The south frigid zone is bounded by the antarctic circle, distant 23°28' from the south pole, which is situated in the centre of this zone. . See fig. 2. - Amphiscii are inhabitants of the torrid zone. They are so called, because their shadows fall north or south at different times of the year. Heteroscii are the inhabitants of the temperate zones, because their shadows at noon fall only one way. The Periscii are those people who inhabit the frigid zones. They are so called, because their shadows, during a revolution of the earth on its axis, are directed towards every point of the com- pass. Antoeci are those who live in the same degree of longi- tude, and in equal degrees of latitude, but the one in north and the other in south latitude. Perioeci are those who live in the same latitude, but in opposite longitudes. Antipodes are those inhabitants of the earth who live diametrically opposite to each other, and consequently walk feet to feet. The Crepusculum, or Twilight, is that faint light which we perceive before the sun rises, and after he sets. It is produced by the rays of light being refracted in their passage through the earth’s atmosphere, and reflected from the different parti- cles thereof. The twilight is supposed to end in the evening when the sun is eighteen degrees below the horizon. The angle of position between two places on the terrestrial globe is an angle at the zenith of one of the places, formed by the meridian, of that place, and a vertical circle passing through the other place, measured on the horizon from the elevated pole towards the vertical circle. - Rhumbs are the divisions of the horizon into thirty-two parts, called the points of the compass. - Problem 1.—To find the latitude of any place.—Rule. Tuºn the globe till the place comes to the graduated edge of the brazen meridian, and the degree on the meridian with which the place corresponds is the latitude north or south, as it may be north or south of the equator. * Example.—Thus the latitude of London is 51} north, and of Lima 12° 1' south. What are the latitudes of Athens, Bengal, the Cape of Good Hope, Cape Horn, Constantinople, Edin- burgh, Ispahan, Madras, Moscow, Paris, Philadelphia, Prague, Stockholm, and Vienna? The answers to these are found from the respective places in the table at the words Latitude and Longitude. Problem 2–To find the longitude of any place.-Rule. Turn the giobe till the place comes to the brazen meridian, and the degree on the equator intersected by the brazen meridian, shews the longitude from London. Example.—The longitude of Madras is eighty degrees east; of Lisbon, nine degrees west. What are the longitudes of Amsterdam, Archangel, Babelmandel, Bengal, Dublin, Gibral- tar, Jerusalem, and Quebec 2 Problem 3–To find any place on the globe, having the latitude and longitude of that place given.—Rule. Find the longitude of the given place on the equator, bring it to that part of the brass meridian which is numbered from the equator towards the poles; and then under the given latitude, on the brass meridian, you will find the place required. e Example.—1. What place has 15139 east longitude, and 34° south latitude : Answ. Botany Bay. Problem 4.—To find the difference of latitude of any two places. —Rule. If the places are in the same hemisphere, bring each to the meridian, and subtract the latitude of the one from that of the other; if in different hemispheres, add the latitude of the one to that of the other, and the sum will shew the diffe- rence of latitude. G. L. O. DICTIONARY OF MECHANICAL SCIENCE. G L O 395 ‘. . Examples.—1. What is the difference of latitude between Philadelphia and Petersburg 2 . Answ. Twenty degrees. - - - 2. What is the difference of latitude between Madrid and Buenos Ayres : Ans. Seventy-five degrees. i - : Problem 5.--To find the difference of longitude between any two places.—Rule. Bring one of the places to the brazen meridian, mark its longitude; then bring the other place to the meridian, and the number of degrees between its longitude and that of the first mark is the difference of longitude. When this sum exceeds 180 degrees, take from it 360, and the remainder will be the difference of longitude. Examples.—1. What is the difference of longitude between Barbadoes and Cape Verd? Answ. 41°48'. . 2. What is the difference of longitude between Buenos Ayres and the Cape of Good Hope 2 Answ. 76° 50'. - . 3. What is the difference of longitude between Botany Bay | and Owhyhee? Answ. 52°45', or 5249. Problem 6.—To find the distance between two places.—Rule. When the distance is less than 90, lay the quadrant of altitude over both the places, so that the division marked O may be on one of the places; then the degree cut by the other place will shew the distance in degrees. Multiply these degrees by 69%, and the product will be the distance in English miles. The dis- tance between two places, with the angle of position, may be found, at the same time, in the following manner:—1. Elevate the globe for one of the places, bring it to the meridian, screw the quadrant of altitude over it; then move the quadrant till it come over the other place, and observe what degree of it this last place cuts. Subtract this distance from 00, and the remainder will be the distance in degrees. The quadrant of altitude, on the horizon, will now shew the angle of position. When the distance is greater than 90, find the antipodes of one of the places, and measure the distance between this and the other place with the quadrant of altitude. Subtract this dis- tance from 180, and the remainder will be the whole distr. º. required. - When the angle of position is required, this case may be per- formed thus: 1. Elevate the globe for the an podes of one of the places, and having fixed the quadrant over it, bring its edge over the other place, and add the degree cut by it to 90, and the sum will be the distance required. 2. The quadrant will shew the position; only, W. must be read for E.; E. for W.; N. for S. ; and S. for N. 3. What is the distance between London and Botany Bay? 154 distance in degrees: 154 distance in degrees. 60 69; 9240 geographical miles. 77 1386 924 10703 English miles. ... Problem 7-The hour being given 3 any place, to find what hour it is in any other part of the world.—Rule. Bring the place at which the time is given to the meridian, set the index to the given hour, then turn the globe till the other place comes to the meridian, and the index will shew the time required. Obs. The earth turns round on its axis from the west towards the east, and causes a different part of its surface to be suc- cessively presented to the sun. When the meridian of any place is directly opposite to the sun, it is then noon to all places on that meridian. Meridians towards the east come opposite to the sun sooner than those towards the west; and hence the peo- ple there have noon much sooner, and all the other hours of the day will be proportionably advanced. The earth takes 24 hours to turn on its axis, and the rate at which it turns every hour *— may be found, by dividing 360° by 24; the quotient, 15, is the number of degrees the earth turns in an hour. Hence it is that a place lying 15° to the east of another, will have noon one hour sooner; if it is 30° or 45°, it will have noon two or three hours sooner than the other; and so on in the same pro- portion for all places further removed. Places that lie 150, 30°, or 45", to the west of that place at which it is noon, will have noon one, two, or three hours later; and so on in the same proportion. . Question for Exercise—What is the hour at Pekin, when it is 9 a.m. at Lisbon ? Answ. Twenty-two minutes after 5 p.m. Calculation.—The difference of longitude is 125° 33' = 8 hours 22 minutes; and, as Pekin is east of Lisbon, this must be added. - 9 hours 0 minutes, a. m. given hour at Lisbon. 8 22 difference of time between the places. 17 22 - 12 0 subtracted. *- Answ. 5 hours 22 minutes p.m. Problem 8.--To adjust the globe for the latitude, zenith, ana sun's place.—Rule. For the latitude: elevate the pole above the horizon according to the latitude of the place, and the globe will be adjusted for the latitude. For the zenith : screw the quadrant of altitude on the meridian at the given degree of latitude, counting from the equator towards the elevated pole, and the globe will be rectified for the zenith. For the sun’s place:* find the sun's place on the horizon, and then bring the place which corresponds thereto, found on the ecliptic, to the meridian, and set the hour-index to twelve at noon, then will the globe be adjusted for the sun's place. . . Examples.—1. Thus to rectify for the latitude of London on the 10th of May. The globe is so placed, that the north pole shall be 5% degrees above the north side of the horizon; then 5.1% will be found on the zenith of the meridian, on which the quadrant must be screwed. On the horizon, the 10th of May answers to the 20th of Taurus: find this on the ecliptic, bring it to the meridian, set the index to twelve, and the globe is rectified for the latitude, zenith, and sun's place, for the 10th of May. * - . . 2. Rectify the globe for London, Petersburgh, Madras, and Pekin, for the 24th of February. . - 3. Find the same sign and degree in the ecliptic on the sur- face of the globe, and this is the sun's place for that day at II OOIl, The sun's place, or, as it is otherwise termed, the sun's longi- tude, may be found for any day of the year in White's Epheme- ris, or in the Nautica Almanack. In White's Ephemeris it is . in the first column of the right-hand page of every n) Onth. 4. What is the Sun's place for March 10th Answ. × 2007". 3. What is the sun’s - lace on the 4th of June? Answ. II 13° 57. - - Problem 9–To find the sun's declination—Rule. Bring the Sun's place for the given day to the brass meridian, and the degree over it will be the declination sought; or bring the day of the month marked on the analemma,t to the brass meridian, and the degree over it will be the declination as before. The sun's declination is given in the table, page 399, for every day in the year. - 1. The declination of the sun being its distance north or south from the equator, this problem is exactly the same as that for finding the latitude of a place. 2. The greatest north declination, 23°28', is when the sun enters Cancer, June 21st, that being the greatest distance of the , *. Find the day of the month on the horizon, and against it, in the adjoining circle, will be found the sign and degree in which the sun is for that day. .* The Analemma is properly an orthographic projection of the sphere on the plane of the meridian ; but what is called the Analemma on the globe is a narrow slip of paper, the length of which is equal to the breadth of the torrid zone. It is pasted on some vacant place on the globe in the torrid zone, and is divided into months, and days of the month, corresponding to the, sun's declination for every day in the year. It is divided into two parts; the right-hand part begins at the winter solstice, or December 21st, and is reckoned upwards towards the summer solstice, or June 21st, where the left-hand part begins, which is reckoned downwards in a similar manner, or towards the winter solstice. On Cary's globes the Analemma somewhat resembles the figure 8. It appears to have been drawn in this shape for the convenience of shewing the equation of time, . by means of a straight line which passes through the middle of it. The equation of time is placed on the horizon of Bardin's globes., G L O G. L. O. DIGTIONARY OF MECHANICAL SCIENCE. ecliptic north of the equator. The greatest south declination, £3° 38', is when it enters Capricorn, December 21st, that being the greatest distance of the ecliptic south of the equator, Examples.—1. What is the sun's declination for March 10th? Answ. 3' 84 south. - - . 2. Also for January 31st 2 Answ. 17° 14 south. * > 3, Also, 1. April 23d 2 2. August 12th ? 3. August 1st' 4. March 5th 2 5. July 23d 2 6. October 19th ! Problem 10.--To rectify the globe for the sun's place, and day of the month.-Find the sun's declination for the given day, by the last problem. Then, if the declination be north, elevate the north pole as many degrees as are equal to it; if south, elevate the south pole. When the globe is rectified for the sun's place, and the sun brought to the zenith, the horizon will be the boundary of light and darkness; it will therefore be day with all those places above the horizon, and night with all those below it. - - Examples.—1. Rectify the globe for the sun's plaee on June 4th. Answ. On June 4th the sun's declination is 22}" north; therefore the north pole of the earth must be elevated 22}" above the horizon. . # 2. Elevate the globe for the sun's place on October 6th. Answ. The sun's declination on October 6th is 5° south; hence the south pole of the earth must be elevated 5° above the horizon. Problem, 11.—To find the sun's rising and setting for a given day, at a given place.—Rule. Elevate the globe for the sun’s declination; bring the given place to the meridian; set the index to twelve, and turn the globe till the given place comes to the eastern edge of the horizon; then the index will shew the time of the sun's rising. Next bring the given place to the western edge of the horizon, and the index will shew the hour at which the sun Sets. figures, make use of that which increases towards the east; the sun's rising and setting may then be found at once, by bring- ing the place only to the eastern edge of the horizon, for the index will point on one row to the hour of rising, and on the other (that which increases towards the west) to the hour of setting. - * * * * * By iii. problem may be found the length of the day and night.— Double the time of the sun's setting, and it will give the length of the day. - Double the time of the sun's rising, and it will give the length of the night. - Examples.—1. Required the time of sun-rise and sun-set at Iondon on the 1st of June. - * , - 2. What time does the sun risé and set at London on July 17th, and what is the length of the day and night?' Problem 12.—A place being given in the north frigid zone, to find when the sun begins to appear above the horizon, and when to disappear; also the length of the longest day and night.—Rule. Elevate the globe for the latitude; bring the ascending signs to the south point of the horizon; observe what degree of the ecliptic is cut by that point; find on the calendar, the day of the month answering to that degree ; and this will be the time of the sun's beginning to appear above the horizon at the given place, which is the end of the longest night. Bring the descending signs to the south point of the horizon, and the day in the calendar, answering to the degree of the ecliptic cut by this point, will be that on which the sun disap- pears; which is the beginning of the longest night. - Bring the ascending signs to the north point of the horizon, and the degree of the ecliptic, indicated as above, will shew when the sun begins to shine continually; which is the begin- ning of the longest day. Bring the descending signs to the same point, and in the same manner it will be found when the sun ceases to shine continually, or the end of the longest day. ' = From the end of the longest night to the beginning of the longest day, and from the end of the longest day, to the begin- ning of the longest night, the sun rises and sets daily. Examples.—1. Whale Island, discovered by Mackenzie, lies in latitude 69° 14′ north : required the time when the sun first appears above the horizon, and when it disappears; also the length of the longest day and night there. Answ. 90° 0' — 69° 14′ north c 20° 46' co-latitude. , * If the hour circle have a double row of The two days when the sun's declination is 20° 46' south, (of a contrary name to the latitude,) are January 17th and Novem. ber 25th ; on the former the sun first appears above the hori- zon, on the latter it disappears. The two days in which the sun's declination is 20° 46' north, (of the same name with the latitude,) are May 24th and July 20th; the former is the begin- ning, and the latter the ending, of the longest day. Hence, at Whale Island, the sun first appears January 17th, and rises and sets daily till May 24th, a space of 127 days: it continues above the horizon from May 24th to July 20th ; therefore the longest day there is equal to fifty-seven natural days. From July 20th it rises and sets daily till November 25th, 127 days, and never rises again till January 17th ; its longest night is therefore equal to fifty-three days. - 2. When does the sun begin to appear above the horizon at North Cape, in Lapland, latitude.72° north ; when does it dis- appear 2 and how many days are the inhabitants without seeing the sum ? Answ. The sum appears January 26, and rises and sets daily till May 15; after which time it continues above the horizon till July 29; then it rises and sets daily till November 16, when it entirely disappears till January 26; the length of the longest night is therefore equal to seventy-one days. Problem 13–To find in what latitude, in the north frigid zone, the sum begins to shine, without setting, on any given day.—Rule. Find the sun's declination on the given day, subtract it from 90°, and the remainder will be the latitude required. The given day must be between March 21st and June 21st. In the same manner it may be found in what latitude, in the south frigid zone, the sun begins to shine, without setting, on any given day between September 23d and December 21st. Examples.—1. In what latitude does...the sun begin to shine, without setting, on April 28d 2 Answ. 77° 31' north. - - 2. In what latitude does the sun begin to shine, without setting, May 15th 2 Answ. 71° 1' north. e Problem, 14.—Having the length of the tongest day in any place, to find the latitude of that place.—Rule. Bring the first of Cancer to the meridian, and set the index to twelve. Then turn the globe westward till the index point to the hour of setting, which is equal to half the length of the day. Raise or depress the pole, till the sun's place is exactly in the western horizon; then will the elevation of the pole be equal to the latitude of the place. . * By this problem it may be found in what latitude any day is of a given length, by bringing the sun’s place for the given day to the meridian, and proceeding as above. Examples.—1. In what latitude is June 21st, sixteen hours long 2 Answ. Latitude 49° north. s . 2. In what latitude is June 21st, eighteen hours long? Answ. latitude 5849 north. . . . & 3. In what latitude is December 1st, fourteen hours long? Answ. latitude 32°46' south. Problem 15–A place being given in the torrid zone, to find two days of the year, when the sun is vertical to that place.—Rule. Bring the given place to the meridian, find its latitude, which mark; turn the globe round, and observe the two points of the ecliptic that pass under this mark. Look upon the calendar for the days corresponding to these points, and these days will be the answer required. . . Otherwise, by the analemma drawn upon the globe, find the latitude of the given place, and bring the analemma to the meridian. Then directly below this latitude will be found, on the analemma, the two days required. - Examples.—On what days is the sun vertical to the follow- ing places? •. 1. Otaheite”. . . . . . . ........... Answ. Jan. 30, and Nov, 11. 2. Rio Janeiro 7.......... . . . . . • — Jan. 2, and Dec. 9. Obs. The first of the above examples may be performed without the globe. * . . - * The latitude of Otaheite is about 17% south, in White’s Ephemeris, or in the table of the sun's declination, p. 399, for those two days on which the sun's declination is 17% south, and they will be found to be about January 30, and November 11. This example is proved thus: From November 11th to December 21st, there are forty days; and from December 31st to January 30th, are forty days: hence the number of days from the time when the sun is vertical, to the nearest solstice, is G. L. O. G L O 397 DIGTIONARY OF MECHANICA1, SCIENCE. equal to the number of days from that solstice to the time when the sun is again vertical. - • * * * * Problem 16–To find all those places in the torrid zone to which the sun is vertical on a given day.--Rule. Find the sun's place for the given day, bring it to the meridian, mark the declination, and turn the globe round, when all those places which pass under that mark of the meridian, will have the sun vertical on the given day. By the analemma, bring the day of the month, marked upon the analemma, to the brazen meri- dian, and mark the declination; then the places will be found as above. - - Examples.—To what places is the sun vertical on November 10th ?—Answ8. To Otaheite, the Great Cyclades, and New Hebrides, in the South Sea; Cape Grafton, in New South Wales; the Island of Madagascar; Monomotapa and Mata- man, in Africa; Punta Gorda, in Brazil; and the southern parts of Amazonia and Peru, in South America. ; 2. To what places is the sun vertical on February 20. Answ. To the same as in the last example. Problem 17.-The day, hour, and place, being given, to find at twhat places of the earth the sun is then rising and setting, where it is noon and midnight.—Rule. Find the place to which the sun is vertical at the given hour, bring the same to the meridian, and adjust the globe to a latitude equal to the sun's declina- tion. Then to all places under the western side of the horizon the sun is rising ; to those above the eastern horizon the sun is set- fing; to all those under the upper half of the brazen meridian, it is moon; and to all those under the lower half, it is midnight. Examples.—1. When it is fifty-two minutes past four o'clock in the morning at London, on the fifth of March, find all places of the earth where the sun is rising, setting, &c. &c. Answ. The sun’s declination will be found to be 64° south ; therefore, elevate the south pole 64° above the horizon. The given time being seven hours eight minutes Before noon, (=12 h.—4h. 52m.) the globe must be turned towards the west till the index has passed over seven hours eight minntes. Let the globe be fixed in this position; then, The sun is rising at the western part of the White Sea, Petersburg, the Morea in Turkey, &c. Setting at the eastern coast of Kamschatka, Jesus Island, Palmerston Island, &c. between the Friendly and Society Islands. Noon at the lake Baikal in Irkoutsk, Cochin China, Cambodia, Sunda Islands, &c. Vertical at Batavia. - Morning twilight at Sweden, part of Germany, the southern part of Italy, Sicily, the western coast of Africa along the AEthiopian Ocean, &c. Evening twilight at the north-west extremity of North Ame- rica, the Sandwich Islands, Society Islands, &c. Midnight at Labrador, New York, western parts of St. Domin- go, Chili, and the western coast of South America. Day at the eastern part of Russia in Europe, Turkey, Egypt, the Cape of Good Hope, and all the eastern part of Africa, almost the whole of Asia, &c. - Night at the whole of North and South America, the western part of Africa, the British Isles, France, Spain, Portugal, &c. 2. When it is four o’clock in the afternoon at London on the 25th of April, where is the sun rising, setting, &c. &c. 2 Answ. The sun's declination being 13° north, the north pole must be elevated 13° above the horizon; and as the given time is four o'clock in the afternoon, the globe must be turned four hours towards the east ; when the sun will be rising at Owhyhee, &c. setting at the Cape of Good Hope, &c.; it will be noon at Bue- nos Ayres, &c.; the sun will be vertical at Barbadoes, and following the problem, all the other places are readily found. Problem 18.—To shew, by the globe, the cause of day and night.— The sun shines upon the earth, and illuminates that half only which is turned towards him; and the other half is in darkness. But, as the earth turns round on its axis, from west to east, once in twenty-four hours, every meridian upon the earth will, in that time, successively be presented to the sun, and be deprived of its light again. . - • Blevate the globe for the sun’s declination, so that the sun may be äu the zenith, and the horizon will be the terminator, or boundary circle, of light and darkness; that half of the earth above the horizon enjoys light; that half below the horizon will be in darkness. - • ‘ - Put a patch upon a globe to represent any place, turn the globe round from west to east, and when the place comes to the Western side of the horizon, the sun appears to the in- habitants of that place to be rising in the east; but it is more properly the inhabitants of that place rising in the west. Go on to turn the globe round, and the place will ascend higher towards the meridian in a contrary direction. - When the place has arrived at the meridian it will then be noon there, and the sun will be at his greatest altitude for that day. - - Continue to turn the globe, and the place will gradually recede from the meridian, and decline towards the eastern horizon, which will cause the appearance of the sun descending towards the west. When the place has arrived at the eastern horizon, as it is then going below the boundary of light and dark- ness, the sun will appear to be setting in the west. The place being now at a greater distance than 90° from that point where the sun is vertical, is deprived of his light, and continues in darkness till by the revolution of the earth it arrives again at the western horizon, when the sun will appear to rise as before. The sun is obviously rising at the same time to all places on the western side of the horizon, and setting at the same time to all places on the eastern side of the horizon. Problem. 19.--To shew, by the globe, the cause of the variety of the seasons.—When the sum is in the equator, the horizon wift represent the terminator, or boundary circle of light and dark- ness; and the poles being made to coincide with it, we shali have a fair representation of the two seasons, spring and autumn; for its rays then extending 90° every way from the vertical point, both poles will be illuminated. When the sun is in the tropic of Cancer, being 234o farther to the north than before, his rays will extend 2330 beyond the north pole on the opposite meridian: they will not, however, reach the south pole by 234°, they will extend to the antarctic only, being 90° distant from the tropic of Cancer: hence, to make the horizon the terminator in this case, the north pole must be elevated 233° above the horizon, and we shall have the Summer season to Europeans. - - When the Sun is in the tropic of Capricorn, the reverse of this takes place; for the sun's rays then extend 2339 beyond the south pole on the opposite meridian, and only as far north as the arctic circle: hence, to make the horizon the termina- tor in this case, the south pole must be elevated 2340 above the horizon, and we shall have the winter season to Europeans. The problems thus given are only to be considered as speci- mens of what may be performed. On the terrestrial globe Butler describes fifty-seven, while on the celestial sphere the number and variety are still much greater. Combined together, they furnish a source of instructive amusement, which but few instruments within the compass of human invention can sur- pass. The exercise is calculated to enlarge the mind, and awaken it to serious and rational contemplations; and in the present day, to be wholly ignorant of their use, is a sure symp- | tom of a defective education. The first person who constructed a globe or sphere, is said to have been Anaximander, a philosopher of Miletus, the capi- tal of Ionia, in Asia Minor. He was born 610 years before Christ, and is reputed to have been the inventor of maps and dials. Since his days, many improvements have been made in their construction and appendages, and much room stili remains for the exercise of ingenuity. Among the remarkable globes which have appeared, that of Gottorp in the academy of sciences of Petersburgh is worthy of notice. This is a large concave sphere eleven feet in diame- ter, containing a table, and seats for twelve persons, to whom the inside surface represents the visible phenomena of the hea- vens. . The stars are distinguished by gilded nails, according to their respective magnitudes, and arranged in groups as the different constellations require. The outside is a terrestrial | globe, representing the land and water on the surface of the earth. It is called the Globe of Gottorp, from being substituted for one originally made in that place, which, with inconceiv- able labour, was conducted upon rollers and sledges over snow 5 I 398 G. L. O , G L 0. DICTIONARY OF MECHANICAL SCIENCE. and through forests to Riga, and thence by sea to Petersburgh, In 1751, it was consumed by fire, and from its iron plates an materials, the present globe was made. - In the lower room of the king's library at Paris, there are two globes nearly equal in dimensions to that at Petersburgh, but much inferior in utility, the globe of Gottorp combining in one, all that is exhibited by both the others. But large as these globes are, they become diminutive when compared with the sphere constructed by the late Dr. Long. This, he tells us, is eighteen feet in diameter; and it will enable thirty persons to sit within its concavity, without any incon- venience. The entrance is over the south pole by six steps. This wonderful machine stands in Pembroke Hall, in the university of Cambridge. All the constellations and stars of the northern hemisphere, visible at Cambridge, are painted upon plates of iron, which, joined together, form one concave surface. Unhappily, it is now very much damaged. Part of the sheathing is destroyed, and the remainder is covered with rust and verdigrise. This neglected state of an ingenious and useful piece of workmanship, reflects, considerable disgrace upon those whose duty it is to keep it in repair. But the dis- grace must be heightened into ignominy, if the report be true, that the interest of £200, Bank annuities, was bequeathed by Dr. Long, to keep the instrument and place in good order. This truly scientific gentleman was a native of Norfolk, and died in 1770, aged ninety-one. - The CelestiAL Globe. See Plate.—Definitions : Obs. The general definitions given of the terrestrial globe apply also to the celestial, the various circles of which are more aptly illus- trated by the- ARMILLARY Sphere,” (see the Plate,) is well adapted to give youth just notions of those imaginary circles which astronomers have applied to what is vulgarly called the concave sphere of the heavens; but by means of those circles, we investigate, with the nicest accuracy, the motions of the celestial bodies, and thus the communication of a sublime science is facilitated. There are six great circles of the sphere, which require par- ticular attention; but which the reader is now acquainted with: they are, the horizon, the meridian, the equator, the ecliptic, the equinoctial colure, and the solstitial colure. . The sphere is contained in a frame, on the top of which is a broad circle, representing the meridian. It is suspended on two pins, at opposite points of the meri- dian. These pins are a continuation of the axis of the sphere both ways, and as the sphere turns round upon them, they are considered as poles, north and south. - The equator goes round the sphere exactly in the middle between the two poles. The ecliptic, the colures, the tropics, and polar circles, have been already defined, and are easily discovered. A The horizon is graduated according to the division of the circle into quadrants and degrees; and to refer celestial ob- jects to the horizon, we have also the points of the compass laid down. Hence the amplitude, or distance, of heavenly bodies, from the east and west points, and their azimuth, or distance from the meridian, are reckoned on the horizon of the armillary sphere. - The graduation of the equator enables us to fix the right ascension of celestial, and the longitude of terrestrial, objects. The graduation of the ecliptic serves to indicate, in the armillary sphere, the latitude and longitude of celestial bodies. The colures are, in a manner, the limits of the year, pointing out the seasons by their two opposite points of the ecliptic. . . The hour circle tells us in what time any motion of the earth, in the centre, is performed. - In fine, many details of the science may be pleasingly and popularly illustrated by this contrivance. The Appearances of the Stars in the Heavens illustrated by the Armillary Sphere.—By placing a small patch of paper on the different circles to represent stars, we perceive, that those which are furthest from the poles will describe the greatest ircles; and that the greatest circles are described by those * So called because it consists of a number of rings of brass, which the old Romans named armilla, from their resemblance, perhaps, to bracelets, or rings for the arms. - stars situated in the celestial equator. A star has acquired its greatest elevation when it comes to the upper semicircle of the meridian, and its greatest depression when it is at the lower circle of the meridian: the meridian bisects its arc of appari- tion. Some circles of revolution are wholly above, others entirely below, the horizon; therefore the patches on those cir- cles shew us which stars descend below, or which never ascend above, the horizon. And any object, whose circle of revolu- tion is on the same side of the equator with the elevated pole, is longer visible than it is invisible; the contrary holds true if it be on the other side of the equator. = The following definitions are more immediately applicable to the celestial globe. - - - - The declination of the sun, of a star, or planet, is its distance from the equinoctial, northward or southward. When the sun is in the equinoctial he has no declination, and enlightens, half the globe from pole to pole. As he increases in north declina- tion he gradually shines farther over the north pole, and leaves the south pole in darkness: in a similar manner; when he has south declination, he shines over the south pole, and leaves the north pole in darkness. The greatest declination the sun can have is 23°28'; the greatest declination a star can have is 90°, and that of a planet 30°28' north or south. The latitude of a star, or planet, is its distance from the ecliptic, north or south, reckoned towards the pole of the eclip- tic, on the quadrant of altitude. Some stars situate in and about the pole have 90° of latitude; the planets have only 80, and the sun being always in the ecliptic has no latitude. The longitude of a star, or planet, is reckoned by the degrees of the ecliptic, from the point Aries round the globe. On the celestial globe the Iöngitude of the sun corresponds with the sun's place on the terrestrial globe. - The right ascension of the sun, or a star, is that degree of the equinoctial which rises with the sun, or a star, in a right sphere, and is reckoned from the equinoctial point Aries east- ward round the globe. - * * - . Oblique ascension of the sun, or a star, is that degree of the equinoctial which rises with the sun, or a star, in an oblique sphere, and is likewise counted from the point Aries eastward round the globe. . - - Oblique descension of the sum, or a star, is that degree of the equinoctial which sets with the sun, or a star, in an oblique sphere. The ascensional or descensional difference, is the difference between the right and oblique ascension, or the difference between the right and oblique descension: and, with respect to the sun, it is the time he rises before six in the spring and sum- mer, or sets before six in the autumn and winter. The angle of position of a star is an angle formed by two great circles intersecting each other in the place of the star, the one passing through the pole of the equinoctial, the other through the pole of the ecliptic. The poetical rising and setting of the stars, is so called be- cause the ancient poets referred the rising and setting of the stars to the sun. - - * * - When a star rose with the sun, or set when the sun rose, it was said to rise and set cosmically. When a star rose at sun- setting, or set with the sun, it was said to rise and set achroni- cally. When a star first became visible in the morning, after having been so near the sun as to be hid by the splendour of his rays, it was said to rise heliacally; and when a star first became invisible in the evening, on account of its nearness to the sun, it was said to set heliacally. - - A Constellation is an assemblage of stars on the surface of the celestial globe, circumscribed by the outlines of some assumed figure, as a bull, a bear, a lion, &c. This division of the stars into constellations direct us to any part of the heavens where a particular star is situated. - The zodiacal constellations are 12 in number; the northern constellations 41, and the southern 46, making in the whole 99. , The largest stars are called stars of the first magnitude. Those of the sixth magnitude are the smallest that can be seen by the naked eye. The figures on the left hand of the annexed tables shew the number of stars in each constellation; R. denotes right ascension, D declination of the middle of the several con- stellations, for the ready finding them on the globe. The modern | constellations are distinguished from the ancient by a star. G. L. O' G. L. O. DICTIONARY OF MECHANICAL SCIENCE. " The Contents of the CelestialGlobe, and the Maps of the Heavens, with the Names of the Signs and Constellations, and of the Principal Stars in each, with their Magnitudes. - | R. 3 1. THE SIGNs of THE Zool Ac. Asc.]á . c. on Aries, the Ram, Arietis 2..... . . . . . . . 30|22|N #) 8 Taurus, the Bull, Aldebaran 1, the 65|16) N. #U Pleiades, the Hyades . . . . . . . . • • || * GTI Gemini, the Twins, Castor 1, Pollux 2 111|52|N ( ga!Cancer, the Crab, º: 4 i.eonis, 128|20||N § Leo, the Lion, Regulus, or Cor Leonis - ă Sl l, #º 150 15||N # / m, Virgo, the Virgin, Spica Virginis 1, 8 || 192 5|N - Vindemiatrix 2 . . . . . . . . . • * * * * * * > * - 5 $ Libra, the Balance, Zubenich Meli 2 ... 226 8S. # 3 ml]Scorpio, the Scorpion, Antares 1. . . . . . 244]26|S. # & 'sagittaſius, the Archer..............|28335|s. ; $ 2. Capricornus, the Goat . . . . . . . . . • * * * * 310|20|S. # 3 : Aquarius, the Water-bearer, Scheat 5 || 335|4|S. # & Sºlpices, the Fishes......... e - e o e º e º 'º' 5|10|N II. THE No RTHERN CoMSTELLATIONS. - 1|Andromeda, Mirac 2, Almaach 2 . . . . . 15|35||N 2|Aquila, the Eagle, with Antinous, Alº 295| 8 ||N tair 1. . . . . . . . . . . . . . . . . . . . . . . . . . $ “” * 3|Canes Vematici, or Asterion and Charaº, the .*.* e e º e º 'º e } 200|40|N * 4|Auriga, the Charioteer, or Waggomer, R - - Capella 1 . . . . . . . . . . . . . . . . . . . .*. 75|45 N * 5|Böotes, Arcturus, Mirac 3 . . . . . . . . . . 212|20||N * 6|Camelopardalus", º§. . . . . 68|70|N # 7|Caput Medusae, the Head of Medusa, - - . Perseus . . . . . . . . . . 0 e º e º e º e } 44|40|N ** 8|Cassiopeia, Schedar 3 . . . . . º º O e. e. e. e. e. e. 12|60|N * 9|Cepheus, Alſº 3 headed ion.) 338|| 65||N * 10|Cerberus”, the Three - heade 09, and Hercules . . . . . . . . . . . . . . tº e º 'º } 271122|N 11|Coma Berenicis, Berenice's Hair .... 185|26||N 12|Cor Caroliº, º: ...a• * ~ * e º 'º 191|39||N 13|Corona Borealis, the Northern Crown, R Alphacca 2 . . . . . . . . . . . . . . . . . . . . 235|30|N * 14|Cygnus, the Swan, Deneb Adige 1 . . . . 308|42||N 15||Delphinus, the Dolphin . . . . . . . . . . . . . . 308||15||N 16|Draco, the Dragon, Rastaben 2 ...... 270|66||N 17|Equulus, the Little Horse. . . . . . . . . . . . 3.16|| 5 | N 18|Frederick’s Ehre, Frederick's Glory . . N * 19|Hercules (see Cerberus) Ras Algethi 1 245|22|N * 20 Lacerto, the Lizard . . . . . . . . . . . . . . . . 336|43||N 21 |Le Messier". . . . . . . . . . . . . . . . . . . . . . . . * 22|Leo Minorº, the Little Lion . . . . . . . . . 150|55|N * 23|Lynx*, the Lyma. . . . . . . . . . . . . . . . . . . . 111 |50 N. 24|Lyra, the Harp, Vega or Wega 1 . . . . . 283|38||N .25|Mons Memalus, the Mountain Menalus 225| 5 |N 26|Musca”, the Fly.... Horse. Maikabº 40|27 N 27|Pegasus, the Flying Horse, Markab 2, Scheat 2 . y © a e ºs e e = e º 0 e º e e e a e U 340|| 14||N * 28 Pº (see Cap. Med.) Algenib *} 46|49| N Algol 2, . . . . . . . . . . . . . . . . . . . . . . . 29|Sagitta, the Arrow. . . . . . . . . . . . . . . . . . 295] 18||N 30|Scutum Sobieskiº, Sobieski's Shield . . . 275|10|N 31|Serpens, the Serpent . . . . . . . . . . . . . . . . . 235||10|N 32|Serpentarius vel Ophiuchus, the Scr- 0|| 13 N T {...”. Ras *% iii. tº º 25 33|Taurus Poniatowski”, the Bull o ºº:: * ºut ºf 275|| 7 ||N 34|Taurus Regalis”, the Royal Bull...... - 35|Triangulum, the Triangle . . . . . . . . . . . . 27|32 |N 36|Triangulum Minus, the Little Triangle | 31|29|N 37|Tubus Herschelii Major, Herschel's Uğ Telescope . . . . . . . . . . . . . . . . * 38|Ursa Major, the Great Bear, Dubhe 1 - U Nº. 2, Benetnach 2......... 15360 N * 39|Ursa Minor, the Little Bear, Polar | Star or Abrukabah 2............ }|230|75|N 110 ! 5l 44 51 108 113 66 71 25 66 58 59 55 35 43 21 81 18 80 1() 113 16 44 22 11 89 18 64 87 24 54 53 40 * 41 I 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 3 5 36 37 38 30| 40 41 43 44 45 46 47 48 49 50 51 52 53 54 Constellations, &c. continued. . Vulpecula et Anser”, the Fox and Goose Taraudus", the Rein Deer . . . . . . . . . . III. The SoutaekN ConstELLATIONs. Apus, vel Avis Indica”, The Bird of \ Paradise . . . . . . e º e s = e s e . . . . . . . $ Ara, the Altar. . . . . . . . . . . . . . . . . . . . . . Argo Navis, the ship Argo, Canopus 1 Brandenburgium Sceptrum”, the Sceptre of Brandenburgh ........ } Canis Major, the Great Dog, Sirius 1.. Canis Minor, the Little Dog, Procyon 1 Centaurus, the Centaur . . . . . . . . . . . . . . Cetus, the Whale, Mencar 2.......... -Chamaeleon”, the Cameleon Circinus”, the Compasses . . . . . . . . . . . . Columba Noachi”, Noah's Dove . . . . . . Corona Australis, the Southern Crown Corvus, the Crew, Algorab 3. . . . . . . . Crater, the Cup or Goblet, Alkes 3.... Crux", the Cross. . . . . . . . . . . . . . . . . • * e e e º e º a e e º º Equileus Pictorious", the Painters’ Easel - a e e º e º 'º e º e º 'º e º e o e s ∈ , e. e. e. e. e. e. e. JEridanus, the River Po, Acherner 1 . Fornax Chemica”, the Furnace . . . . . . Grus”, the Crame. . . . . . . a e e º e º e º e º e a e Horologium”, the Clock. . . . . . . . . . . . e Hydra, the Water Serpent, Cor Hy- drael. . . . . . . . . . . . . . . . . . . º Hydrus, the PWater Snake........ © e º e Indus”, the Indian . . . . . . . . . . . . - - - - - - Lepus, the Hare. . . . . . . . . . © º º º e º 'º e º e Lupus, the Wolf. . . . . . . . . . . . . . . . tº e º º Machina Pneumatica”, the Air Pump Microscopium”, the Microscope ....., Monoceros”, the Unicorn . . . . . . . . . . . . Mons Mensae”, the Table Mountain . . Musca Australis, vel Apis, the Sow- \ thern Fly or Bee. . . . . . . . . . . . . . . . $ Norma, vel Quadra Euclidisº, Euclid's Square . . . . . . . . . . . . . . tº º a c e º e s - e. Octans Hadleianus”, Hadley's Octant Officina Sculptoria”, the Sculptor's Shop . . . . . . . . . . . . . . . . . . . . . . . . . . Orion, Betelgeux 1, Rigel I, Bella- trix 2. . . . . . . . . . . . . . . . . . . . . . . . . . Pavo”, the Peacock Phoenix" . . . . . . . . . . . . . . . . . . . . . . . . . . Piscis Notus vel Australis, the Sou-h Piscis Wolans”, the Flying Fish ...... Praxiteles, vel Cela Sculptoria”, the Engraver’s Tools . . . . . . . . . . . . . . . . } Pyxis Nautica”, the Mariner's Com- * * * * * * * * * - * * * * * * * * * * * * * * * * boidal Net...... & © tº e º e º e º e º e º e º e Robur Caroli, Charles's Oak. . . . . . . . . . Sextans”, the Sea:tant ... . . . . . . . . . . . Solitaire, an Indian Bird. . . . . . . º e º e e Telescopium, the Telescope . . . . . . . . . . Psalterium Georgianum", the Geor- \ gian Psaltery...... Q & © & © a e e o 'º e e s e $ Touchan, the American Goose ........ Tubus Herschelii Minors, Herchell’s & Less Telescope . . . . . . . . . . . . . . . . Triangulum Australis", the South A Xiplias, (see Dorodo)......... * c & © tº e e Montgolfier's Balloon......... * c e e o e a The Press of Guttenberg . . . . . . . . . tº a e Le Chat, the Cat . . . . . . . . . . ſº tº tº e º tº a c • * Asc. 300 Dorado or Xiphias”, the Sword Fish . } : thern Fish, Fomalhaut 1 . . . . . . . . $ R. 30 252 255 115 467 105 110 200 85 330 40 139 359 238 175 222 278 185| 168 183 75 84 60 315 230 150 315 110 76 185 242 310 80 302 1() 335 127 68 130 62 159 145 278 75 60 50 65 62 68} § S. º 13 12 60 10 13 #00 G. L. O. G (§ 0. DIGTFONARY OF MECHANICAL SCIENCE. Mote. The constellations 18, 21, 34, 37, in the northern, and 45, 47, 52, 53, and 54, in the southern hemisphere, are inserted because foreign astronomers have given them a place in the heavens, though our British globe makers have not yet engraven them on their plates. They are to be found, however, in the maps of Dr. Jamieson's Caelestial Atlas. The ancients divided the stars into different groups, called constellations, and gave particular names to each, which names the greater part of them have hitherto retained. The Pleiades and Orion are mentioned in the sacred writings by Job, and Homer and Hesiod describe several constellations by names which are now in general use. w A TABLE of the Time of Culminating A knowledge of the principal constellations in the heavens will be an useful acquisition to the student, and this may be obtained by noting the time when they come to the meridian, that is, to the south. . . . . . . * * * . - - There are few persons who are unacquainted with the seven (sia: ) stars called the Pleiades, or the beautiful constellation of Orion. The Pleiades come to the meridian of London about an hour before Aldebaran, and Grion culminates an hour after that star; and since the diurnal difference of time of a star's culmi- nating is nearly equal to the diurnal difference of the sun's right ascension, viz. about four minutes; a star will rise, come to the meridian, and set, nearly four minutes earlier every day, or about two hours in a month. - - - of the Zodiacal Constellations on the first Day of every Month, and the Semi-diurnal Arc at London.—N. B. The Time is reckoned from Noon to Noon. - - t . : ſ * Zodiacal Constellations. Jan. Feb. Mar, April. May. June. July. Aug. Sept. || Oct Nov. Dec. S. Diur. Arc. i , H |Aries, Arietes, a. . . . . . .] 73 5 || 3} 14 || 233 21, 19 17 15 13} 11; 93 84 H. jTaurus, Aldebaran, a. . . . 93 7% 5% 3# 1; 233 21; 193 || 173 | 163 || 14 11; 74 H. Gemini, Castor, a........ 12} | .10% 8# 6# 4% 25 | 123 22} | 20% 183 || 17 15 93. H. Cancer, Acubene, a. ....] 14 11% 10} 8} 6% 44 2 12 22 20+ | 18} | 16; 74 H. Leo, Cor Leonis, a...... 15% 13 11% 9} | . 7% 5} 3} 14 || 23# 214 19% 17% 7} H. Virgo, Spica, a..........| 18% | 163 14% 12% 10% 8% 6} 4% 2} | 12% 22# 20} 15% H. | ||Libra, – a... . . . . . ... 19á 17% 15% | 1.4 123 10 8 6 4} | 2+ | 12+ | 104 4# H. Scorpio, Antares, a. . . . . . 21% 19á 174 15% | 13% 113 9; 73 53. 33 2. 233 3% H. Sagittarius, Bow, 3. ....] 23# 213 | 19% 17# 15% | 13} | 11} 9} |. 7% 5} 3# 1% 3 H. || Capricornus, Horn, 3. ... 14 || 23 213 194 || 17% 15% 13% il? | 9% # 5% 33 43 H. |Aquarius, R. Should. a. 3% l 23# 21+ 19% 17% 15% 13+ . . . 114 9% 7; 5% 5; H. Pisces, String, a. . . . . . . 7 4; 3 . l 23# 213 18; 163 | 1.4% 13 11} 9} 6} H. Problems performed by the Celestial Globe.—Problem 1.--To jind the right ascension and declination of the sum, or a star.— Rule. Bring the sun, or star, to that part of the brass meridian numbered from the equinoctial towards the poles, and the degree on the brass meridian is the declination, and the right ascension will be indicated by the degree on the equinoctial, between the brass meridian and the point Aries. Or place both the poles of the globe on the horizon, bring the sun or star to the eastern part of the horizon; then the number of degrees which the sun or star is northward or southward of the east, will be the declination north or south ; and the degrees on the equinoctial, from Aries to the horizon, will be the right ascension. • - . Examples. 1. Required the right ascension and declination of a Dubhe, in the back of the Great Bear.—Answer. Right ascension 162° 49', declination 62° 48' N. - Problem 2.— To find the latitude and longitude of a star.—Rule. Place the upper end of the quadrant of altitude on the north or south pole of the ecliptic, according as the star is on the north or south side of the ecliptic, and move the other end till the star comes to the graduated edge of the quadrant; the number of degrees between the ecliptic and the star is the latitude; and the number of degrees on the ecliptic, reckoned eastward from the point Aries to the quadrant, is the longitude. Or, elevate the north or south pole 664° above the horizon, according as the given star is on the north or south side of the ecliptic; bring the pole of the ecliptic to that part of the brass meridian numbered from the equinoctial towards the pole ; the ecliptic will then coincide with the horizon: screw the quadrant of altitude upon the brass meridian over the pole of the ecliptic ; keep the globe from revolving, and move the quadrant till its graduated edge comes over the given star; the degree on the quadrant cut by the star is its latitude; and the sign and degree on the ecliptic cut by the quadrant shew its longitude. Examples. 1. Required the latitude and longitude of a Aldebaran in Taurus?—Answ. Latitude 60 28 S. longitude 2 signs 6°53'; or 6° 53' in Gemini. - Problem 3.—The right ascension and declination of a star, the moon, a planet, or of a comet, being given, to find its place on the globe.- Bring the given degrees of right ascension to that part of the brass meridian numbered from the equinoctial towards the poles; then, under the given declination on the brass meri- dian, you will find the star, or the place of the planet. Examples. 1. What star has 261° 29' of right ascension, and 52° 27' north declination? Answ. 3 in Draco. - 2. On the 20th of August, 1805, the moon’s right ascension was 91°3', and her declination 24° 48'; to find her place on the globe at that time. Answ. In the milky way, a little above the left foot of Castor. - * Problem. 4.—The iatitude and longitude of the moon, a star, or a planet given, to find its place on the globe.—Place the division of the quadrant of altitude marked O, on the given longitude in the ecliptic, and the upper end on the pole of the ecliptic; then under the given latitude, on the graduated edge of the qua- drant, you will find the star, or place of the moon, or planet. Examples. 1. What star has 0 signs 6° 16' of longitude, and 12° 36' N. latitude. Answ. y in Pegasus. : 2. On the fifth of June, 1820, at midnight, the moon's longi- tude was 5s 15° 6', and her latitude 1° 45' N.; find her place on the globe. . . . . - . Problem 5.--To find the rising, setting, and culminating of any star, its continuance above the horizon, its oblique ascension and descension,-and its eastern and western amplitude, for any given day and place.—Rectify the globe, and bring the given star to the eastern part of the horizon, the index will shew the hour of rising ; the degree of the equinoctial that rises with the star is its oblique ascension; and the distance of the star from the east point of the horizon is its eastern or rising amplitude. When the star is brought to the meridian, the index will shew the time of culminating. . - Bring the star to the western quarter of the horizon, and its setting, oblique descension, and western amplitude, will be found in the same manner as its rising, eastern amplitude, and oblique ascension. g The number of hours from rising to setting will be the time of its continuance above the horizon. - Examples. 1. On the ninth of February, when it is nine o'clock in the evening at London, what stars are rising, what stars are setting, and what stars are on the meridian.—Answ. Alphacca, in the northern Crown, is rising; Arcturus and G. L. O G. L. O. 461 I) ICTIONARY OF MECHANICAL SCIENCE. Mirach in Büotes, just above the horizon; Sirius on the meri- dian ; Procyon and Castor and Pollux, a little east of the meridian. The constellations Orion, Taurus, and Auriga, a little west of the meridian ; Markab in Pegasus, just below the western edge of the horizon, &c. - 2. On the 20th of January, at two o'clock in the morning, at London, what stars are rising, what stars are setting, and what stars are on the meridian 2 Answ. Vega in Lyra, the head of the Serpent, Spica Virginis, &c. are rising; the head of the Great Bear, the claws of Cancer, &c. on the meridian ; the head of Andromeda, the neck of Cetus, and the body of Colum- ba Noachi, &c. are setting. . 3. When does Sirius rise at London, on March 14; at what time comes it to the meridian, and set; how long does it con- tinue above the horizon; what are its oblique ascension and descension, and its eastern and western amplitude : Answ. Rises at . . . . . . . . . tº e g º ºs e e º e 2h 24m. p. m. Culminates . . . . . . . . . . . . . . . . 6 57 p.m. Sets . . . . . . . . . . . . . . . . . . . . . . 11 30 p.m. Above the horizon . . . . . . .. . . . 9 6 Oblique ascension. . . . . . . . . . 120° 47' Oblique descension . . . . . . . . 77 17 'Amplitude . . . . . . . . . . . . . . . . 27 O S. 4. Required the same for Fomalhaut, at the Cape of Good Hope, on December 10th ? Answ. Rises . . . . . . tº gº e º e º & º ºs ºs e º & s 10h 0m. a. m. Culminates . . . . . . . . . . . . . . . . 5 30 p.m. Sets . . . . . . . . . . . . . . . . . . . . . . 1 0 a. m. Above the horizon. . . . . . . . . . 15 0 Oblique ascension, . . . . . . . . . 3179 0. Oblique descension . . . . . . . . 5 0 Amplitude . . . . . . . . . . . . . . . . 38 0 S. Problem 6–To represent the face of the heavens for any given day and hour, in any given latitude.—Adjust the globe as in the preceding problems, by bringing the sun’s place to the meri- dian, putting the index to 12, and then turning the globe to the given hour; and the stars in the heavens will appear exactly in the same situations as they are upon the globe. Examples. 1. Required the situation of the stars for the latitude of Newcastle, on October 6th, at eight o'clock in the evening. In this survey we commence at the north point of the horizon, and proceed eastward, noticing the different con- stellations, and the relative situation of the stars in these constellations. The first star which strikes the eye of the observer, in the north-east part of the heavens, is Capella, in the constellation Auriga, or the waggoner: it is of the first magnitude, of the altitude of 22°, or nearly the fourth part of the distance from the horizon to the zenith. There are two stars of the second magnitude, which form with Capella a triangle: the star which forms the short side of the triangle is in the right shoulder of Auriga, and is marked 3; it lies at the distance of about 8° from Capella, further to the north; its altitude is 18°; the star forming the longer side of the triangle is in the Bull's northern horn: its distance from Capella is not more than 25°; its altitude not more than 5°; azimuth N. E. There are three stars of the fourth magnitude, a little to the south of Capella, that bear the name of the Kids. If a line be drawn through the two stars that form the upper side of the triangle, and continued to the horizon, it will point out Castor, a, in Gemini, just rising; azimuth, E. N. E. : it is between the first and second magnitude. The other stars in this constellation have not yet risen. A line, drawn between Castor and Capella, and continued higher in the heavens, will point out Perseus, in which there are three stars, one of the second magnitude, a, named Algenib, and two of the third magnitude, one on each side of Algenib, at the distance of about 5°; they form a line, a little curved on the side next Auriga. The altitude of Algenib is 379; azi- muth, N. E. by E. g A little to the south of Perseus is the head of Medusa, which Perseus is holding in his hand. Besides two or three smaller stars, it contains one of the second, and one of the third mag- nitude: the name of the brightest is Algol; altitude 339; azimuth, E. N. E. Algol is only 10° distant from Algenib. biº below the head of Medusa, about 14° above the horizon, are the Pleiades, or Seven Stars; they are situated in the shoulder of Taurus, and are so easily known, that nó description is necessary. Aldebaran, a star of the first magni- tude, which forms the eye of Taurus, is just rising ; azimuth, E. N. E. A vertical circle, drawn through Algol, will point to it. There are two stars of the third magnitude, and several smaller, very near Aldebaran, which form with it a triangle. The whole cluster is called the Hyades. • A line drawn from Aldebaran through Algol, and continued to the zenith, will direct to Cassiopeia. This contains five stars of the third magnitude, besides several of the fourth : it is in form something like the letter Y, or, as some think, an inverted chair. It is situated above Perseus, within 30° of the zenith. The altitude of the brightest star a, called Schedar, is 60°; azimuth, E. N. E. - Below Cassiopeia, and west of Perseus, is Andromeda, which contains three stars of the second magnitude. A line from Algenib, parallel to the horizon, towards the south, will pass very near these three stars; and as they are all of the same magnitude, and placed nearly at the same distance of 15° from each other, they may easily be known. The name of the star nearest Perseus, and which is in the foot of Andromeda, mark- ed y, is Almaack: its altitude is 49°; azimuth, E. N. E. The name of 3, in the girdle, is Mirach ; its altitude 449; azimuth, E. The altitude of a, in the head of Andromeda, is 46°; azi- muth E. S. E. About 18° below Mirach are two stars in Aries, not more than 59 distant from each other, forming with Mirach an isosceles triangle : the most eastern star a, is of the second magnitude ; the other, 3, of the third, attended by a smaller star, marked Y, of the fourth magnitude. A line drawn from Mirach, perpendicular to the horizon, will pass between the two, and, besides, will point to a star of the second magni- tude, directly E. not 30 above the horizon. The star is the first of Cetus, marked a, and is of the second magnitude; it is named Menkar: a line, drawn from Capella through the Pleiades, will also point to it. Cetus is a large constellation, and contains eight stars of the third magnitude; they all lie to the west of Menkar; 3, a star in the tail, is more than 400 degrees distant from it. The azimuth of 3 is S. E. by E.; altitude nearly the same as Menkar. The constellation Pisces is situated next to Aries; it con- tains one star of the third magnitude, marked a ; its altitude is 100; azimuth, E. by S. ; it is distant from Menkar 15°. A line drawn from Almaack, through a in Aries, will point to it. If we return again to a, in the head of Andromeda, we shall find three other stars nearer the meridian, which with it form a square : these stars are in Pegasus, and are placed at the distance of 15° from each other ; they are all of the second magnitude. The two stars forming the western side of the square are called, the upper one Scheat, which is marked 3, and which is in the thigh of Pegasus; the under one Markab, which is marked a, and which is in the wing: the lowest star in the eastern side of the square is in the tip of the wing, and is marked y. The altitude of the Scheat is 559; azimuth, S. E. # E. Altitude of Markab, 430; azimuth, S. E. by S. # E. A line drawn through y and 3 (the diagonal in the square of Pergasus,) and continued to the meridian, will point out Cyg- nus, a remarkable constellation, in the form of a large cross, in which there is a star of the second magnitude, named Deneb or Arided ; it is marked a, and is almost directly upon the meri- dian, at the altitude of 800. Cygnus contains six stars of the third magnitude. The constellation Cepheus, which con- tains no remarkable stars, is situated between Cygnus and the north pole. - Below Pegasus, and nearer the meridian, is Aquarius, con- taining four stars of the third magnitude. . A line drawn from a in Andromeda, through Markab, will point to a in Aquarius. Its altitude is 329; azimuth, S. S. E. A bright star of the first magnitude, named Fomalhaut, in Piscis Australis, is then upon the horizon; azimuth, S. S. E. Delphinus, a small constellation, about 30° below Cygnus, upon the meridian, contains five stars of the third magnitude; four of them are placed close together, and form the figure of a lozenge. A line drawn through the two under stars of the square, will point to it : its altitude is about 50. 5 K 402 g Lo G L U. DICTIONARY OF MECHANICAL SCIENCE. A little to the west of Delphinus, but not quite so high, is Aquila, containing one very bright star of the first magnitude, named Atair: it may very easily be known, from having a star on each side of it, of the third magnitude, forming a straight line, the length of the line is only about 5°. Altitude of Atair, 400; azimuth, S. S. W. º + . Considerably above Atair, and a little to the west of Cygnus, is Lyra, containing a star of the first magnitude, one of the most brilliant in the firmament. It is called Lyra, or Vega, and is 35° to the north-west of Atair: altitude 60° ; azimuth, W. S. W. Lyra, Atair, and Arided form a large triangle. We come now to notice three constellations, which occupy a large space in the western side of the heavens: these are, Her- cules, immediately below Lyra ; Serpentarius, between Her- cules and the horizon, extending a little more towards the south ; and Böotes, reaching from the horizon W. N. W. to the altitude of 45°. . Hercules contains eight stars of the third magnitude: the star in the head, a, named Ras Algethi, is within 5% of a, in the head of Serpentarius. This last is a star of the second magni- tude, and is named Ras Alhague: its altitude is 309; azimuth S. W. by W. & W. . A line drawn from Lyra, perpendicular to the horizon, will pass between these two stars. The other stars in Hercules extend towards the zenith, and those in Ser- mentarius towards the horizon. The constellation Böotes may easily be known from the bril- liancy of Arcturus, a star of the first magnitude, and supposed to be the nearest to our system of any in the northern hemisphere: it is within 10% of the horizon; azimuth, W. N. W. Böotes also contains seven stars of the third magnitude, mostly situ- ated higher in the heavens than Arcturus. The star imme- diately above Arcturus is called the Mezen Mirach, and is marked s. The star in the left shoulder, Ö, named Seginus, forms, with Mirach and Arcturus, a straight line. Between Serpentarius and Böotes is Serpens, containing one star of the second and eight of the third magnitude ; a, in Serpens, is nearly at the same distance from the horizon as Arcturus; azimuth, W. - - Above Serpens, and a little to the east of Böotes, is the Northern Crown, containing one star of the second magnitude, named Gemma, and several of the third, which have the ap- pearance of a semicircle. A line, drawn from Lyra to Arcturus, will pass through this constellation. - - - ... We come now to Ursa Major, a constellation containing one star of the first, three of the second, and seven of the third magnitude. It may be easily distinguished by those seven stars, which, from their resemblance to a waggon, are called Charles's Wain. The four stars in the form of a long square are the four wheels of the waggon; the three stars in the tail of the Bear, are the three horses, which appear fixed to one of the wheels. The two hind wheels (a named Dubhe and 3,) are called the pointers, from their always pointing nearly to the north pole; hence the pole star may be known. The altitude of Dubhe is 300; azimuth, N. by W. H. W. : the distance be- tween the two pointers is 5%; the distance between the pole star and Dubhe the upper pointer is 33°. Ursa Minor, besides the pole star, of the second magnitude, situated in the tail, contains three of the third, and three of the fourth magnitude. These form some resemblance to the figure of Charles's Wain inverted, and may easily be traced. Draco, containing four stars of the second, and seven of the third magnitude, spreads itself in the heavens near Ursa Minor; the four stars in the head are in the form of a rhom- bus, or lozenge ; the tail is between the pole star and Charles's Wain. g - Besides these constellations, there are a number of others, which, as they contain no remarkable stars, we have not described : an enumeration of these will suffice. The Lynx, between Ursa Major and Auriga; Cameloparda- lus, between Ursa Major and Cassiopeia ; Musca and the Greater or Less Triangles, between Aries and Perseus ; Equuleus, close to the head of Pegasus; Sagittarius, setting in the S. W.; Antinous, and Sobieski's Shield, below Aquila; the Fox and the Goose, between Aquila and Cygnus; the Greyhounds, and Berenice's Hair, between Böotes and Ursa Major: and Leo Minor, below Ursa Major. - - astringent taste. As one day brings the stars nearly four minutes earlier into, the same situation than they were on the preceding day; by making that allowance, the above view of the heavens will answer for September 6th, about 10 o'clock; September 21st, about mine o’clock; or October 21st, about seven o'clock in the evening. - x - - 2. Point out the situation of the stars for the latitude of Lon- don, on January 1st, at eight o'clock in the evening. . . . 3. Required the situation of the stars for the latitude of Paris, on March 21st, at nine in the evening. - - 4. What are the principal constellations that will be above the horizon of Edinburgh, on May 1st, at ten o’clock in the evening. 4. GLOBULAR CHART, the representation of the surface, or of some part of the surface, of the terrestrial globe upon a plane, wherein the parallels of latitude are circles nearly concentric, the meridian curves bending towards the poles, and the rhomb lines are also the curves. . - GLOBULAR Projection. See MAP. GLOBULAR Sailing. See SAILING. GLOW Worm. See LAMPYRIS. - GLUCINA, in Chemistry, an earth so named from its sweetish taste, and which in the powder or in fragments is almost three times as heavy as water. It is, infusible in the fire, does not contract like alumina, by great heat, and has no effect on vegetable colours. It is insoluble in water, but combines with acids, making with them soluble salts, distinguished by a slightly It was first discovered in aqua marina. GLUE, among Artificers, a tenacious viscid matter, which serves as a cement to connect things together. Glues are of different kinds, according to the various uses they are designed for, as the common giue, glove glue, parchment glue, isinglass glue, &c. The common or strong glue, is made of the skins of animals; as oxen, cows, calves, sheep, &c., and the older the creature is, the better is the glue made of its hide. Indeed, whole skins are but rarely used for this purpose, but only the shavings, parings, or scraps of them; or the feet, sinews, &c. In making glue of parings, they first steep them two or three days in water; then washing them well out, they boil them to the consistence of a thick jelly, which they pass, while hot, through osier baskets, to separate the impurities from it, and then let it stand some time to purify it further: when all the filth and ordures are settled to the bottom of the vessel, they melt and boil it a second time. They next pour it into flat frames or moulds, whence it is taken out pretty hard and solid, and cut into square pieces or cakes. They afterwards dry it in the wind, in a sort of coarse net; and at last string it, to finish its drying. The best glue is that which is oldest; and the surest way to try its goodness, is to lay a piece to steep three or four days, and if it swell considerably without melting, and when taken out resume its former dryness, it is excellent. A glue that will hold against fire or water may be made thus: mix a handful of quick lime with four ounces of linseed oil, boil them to a good thickness, then spread it on tin plates in the shade, and it will become exceedingly hard, but may be dissolved over a fire, as glue, and will effect the business to admiration. - * , , GLUE, Method of Preparing and Using.—Set a quart of water on the fire, then put in about half a pound of good glue, and boil them gently together till the glue be entirely dissolved, and of a due consistence. When glue is to be used, it must be made thoroughly hot; after which, with a brush dipped in it, besmear the faces of the joints as quick as possible; then clapping them together, slide or rub them lengthwise one upon another two or three times, to settle them close; and so let them stand till they are dry and firm. • . . GLUE, Parchment, is made by boiling gently shreds of parch- ment in water, in the proportion of one pound of the former to six quarts of the latter, till it be reduced to one quart: the fluid is then strained from the dregs, and afterwards boiled to the consistence of glue. Isinglass glue is made in the same way: but this is improved by dissolving theisinglass in alcohol, by means of a gentle heat. See CemeNT. - . . . . GLUTEN. With the fecula and saccharine matter which compose the principal part of nutritive grain, is another sub- stance approaching more nearly in its characters to animal G. N. O. G O A DICTIONARY OF MECHANICAL SCIENCE. 403 matter than any other product of the vegetable system. From the resemblance in its properties to the animal principle for- merly called gluten, but now described under the term fibrin, it has received the name of vegetable gluten. It is obtained in large quantities from wheat, amounting to the 12th part of the whole grain, by kneading the flour into paste, which is to be washed very cautiously, by kneading it under a jet of water till the water carries off nothing more, but runs off colourless; what remains is gluten: it is ductile and elastic; it has some resemblance to animal tendon or membrane; it is very tena- cious, and may be used as a cement for broken porcelain vessels. It has a peculiar. smell, with scarcely any taste. When exposed to the air it assumes a brown colour, and becomes apparently covered with a coat of oil. When com- pletely dry it resembles glue, and breaks like glass. It is insoluble in water, alcohol, and ether; but the acids dissolve it, and the alkalies precipitate it. It has a strong affinity for the colouring matter of vegetables, and likewise for resinous sub- stances. When kept moist, it ferments, and emits a very offensive smell; the vapour blackens silver and lead. Its constituent parts are oxygen, hydrogen, carbon, and azote. Though it exists most abundantly in wheat, it is found in large quantities in many other plants. It is gluten that renders wheat so fit for bread. - - * GLYCYRR HIZA, or Liquorice, a genus of the diadelphia- decandria class and order. Natural order of papilionaceae or leguminosae. There are four species; tall perennial, herba- ceous plants, with the stalks somewhat woody at the bottom. Their propagation is effected by cuttings of the small roots. An open situation and a deep loose soil is the most suitable for. them. In three years the roots will be fit to take up. Liquorice is almost the only sweet that quenches thirst, and has been employed in hydropic cases, to prevent the necessity of drink- ing. An extract is made from the root. GNAT. See CULEx. - - GNEISS, in Mineralogy, composed of felspar, quartz, and mica, forming plates, laid on each other, and separated by thin layers of mica; differs from granite by being divisible like slate; though, like that, it sometimes contains schorl and garnet. The beds of gneiss sometimes alternate with layers of granular Himestone, schistose, hornblende, and porphyry. It is rich in ores; almost every metal has been found in gneiss rocks, either in veins or beds. Sometimes gneiss is found in a curved form, of which there are some very remarkable rocks in the island of Lewis, one of the Hebrides. GNOMON, in Astronomy, is an instrument or apparatus for measuring the altitudes, declinations, &c. of the sun and stars. The gnomon is usually a pillar, or column, or pyramid, erected upon level ground, or a pavement. For making the more considerable observations, both the ancients and moderns have made great use of it, especially the former; and many have preferred it to the smaller quadrants, both as more accu- rate, easier made, and more easily applied. The most ancient observation of this kind extant, is that made by Pytheas, in the time of Alexander the Great, at Marseilles, where he found the height of the gnomon was in proportion to the meridian shadow at the summer solstice, as 213% to 600; just the same as Gassendi found it to be, by an observation made at the same place, almost 2000 years after, viz. in the year 1636. The elevation of the pole may be found by means of the gno- mon, by finding the meridian height of the sun; for this being given, we have the elevation of the equator, and consequently that of the pole. The meridian height of the sun may be found in the following manner: Let A C, - - in the annexed figure, represent the gnomon, A B the shadow, C B part of a ray drawn from the centre of the sun passing by the top of the gnomon, and terminating the sha- dow at B. These lines form the right- angled triangle A B C, and of which the two legs A B, A C may be sup- posed given, their lengths being . - accurately found by measurement; then having the two sides, and knowing the angle at A to be a right angle, the angles at B and C are easily found by the known rules of trigonometry: : of projection, is projected into a conic section. principal varieties of the common goat : the former of which will give the sun's meridian altitude, and hence the latitude of the place. - This method of observation, however, is by no means accu- rate, as is proved by the following deficiencies in the ancient observations made in this manner: 1. The astronomers did not take into account the sun's parallax, which makes his apparent altitude less than it would be if the gnomon were, placed at the centre of the earth. 2. They neglected refrac- tion, by which the apparent height of the sun is somewhat increased. 3. They made their calculations as if the shadows were terminated by a ray coming from the sun's centre; whereas it is bounded by one coming from the upper edge of his limb. These errors, however, may be easily allowed for; and when this has been done, the ancient observations are generally found to coincide nearly with those of the moderns. GNOMON, in Dialling, is the style-pin, or cock of a dial, the shadow of which points out the hours. This is always sup- posed to represent the axis of the world, to which it is there- fore parallel, or coincident, the two ends of it pointing straight to the north and south poles of the world. # G. No Mon, in Geometry, is the space included between the lines forming two similar parallelograms, of which the smaller is inscribed within the larger, so as to have one angle in each com- mon to both. - - Thus A G FE and A B C D being similar parallelograms, having a common angle at A ; then the space G B C F D E is called a gnomon. In the same manner, if G F and E F be produced to H and I, forming another similar paralle- logram F. H C F, then is also the space F H B A D I a gnomon; and the same may otherwise be formed about the angles D and B. GnomoNIC, or GNo Monic AL Projection, that which repre- sents the circle of a hemisphere upon a plane touching it in the vertex, by lines or rays from the centre of the hemisphere to all the points of the circles to be projected. In this projection all the great circles of the sphere are projected into right lines. Any lesser circle parallel to the plane of projection, is project- ed into a circle. And any lesser circle not parallel to the plane The gnomonic projection is also called the horologiographic projection, because it is the foundation of dialling. In other respects it is not much used, because the circles of the sphere are projected into conic Sections, which are difficult to be described. However, this projection has its conveniences in the solution of some pro- blems of the sphere, on account of the great circles being all projected into right lines. Emerson has given a theory and practice of the gnomonic projection, in his treatise on the “Projection of the Sphere.” - # GNOMONICs, the art of dialling, or of drawing sun and moon, dials, &c. on any given plane, so called, as it shews how to find the hour of the day, &c. by the shadow of the gnomon or style. GNOSTICS, in Church History, a sect of Christians, so called from their pretensions to be more enlightened than others, and from their affecting to be able to bring mankind to the knowledge of the true God. GOAT, in Zöology, Capra, a genus of quadrupeds, of the order of pecora, of which there are nine species and varieties, viz. 1. Capra Ibex, found in several parts of Europe and Asia, dwells in mountainous parts, and is an animal of great strength and agility. The colour is a grayish brown. 2. Capra AEgagrus, or Caucasian Ibex, larger than the common goat, in some de- gree resembles a stag. The female has neither horns nor beard. It inhabits the highest parts of mount Caucasus, and is strong and swift. 3. Capra Hircus, or common goat, found in almost every part of the globe is various of colour, being black, brown, white, or spotted. The flesh is good when young, and the skin is used for making gloves. The goat goes with young four months and a half. The leather made of the skin of the Chamois goat is highly esteemed. The following are the 1. Capra Mambrica, or Syrian goat, is remarkable for its cars, which are long and pendulous. 2. Capra Angorensis, or Angora goat, is generaliy 404. G. O. L. G O O DICTIONARY OF MECHANICAL SCIENCE, of a milk-white colour, short-legged, with black, spreading, spirally twisted horns, and the hair on the body hanging in spiral ringlets. From this hair fine camblets are made. 3. Capra Depressa, or African goat, is a very small kind, found in some parts of Africa. 4. Capra Reversa, or Whidah goat, is also a dwarf variety found in Africa, where it is much esteemed as an article of food. 5. Long-horned Whidah goat. 6. Capri- Corn goat. GQBIUS, the Goby, in Natural History, a genus of fishes of the order thoracici, of which there are twenty-five species. GOD, the Supreme Being, the first Cause, or Creator of the universe, the upholder and governor of all things, and the only true object of religious worship. - GODFATHERS and GODMOTHERS, persons who at the baptism of infants lay themselves under an indispensable obligation to instruct them in the principles of Christianity, and watch over their conduct. GOGGLES, in Surgery, instruments used for the cure of squinting, or that distortion of the eyes which occasions this disorder. They are short conical tubes, composed of ivory stained black, with a thin plate of the same ivory fixed in the tubes; through the centre of the plates is a small circular hole, about the size of the pupil of the eye, for the transmission of the rays of light. GOLD. See AURUM. GoLD Wire, a cylindrical ingot of silver, superficially gilt, or covered with gold at the fire, and afterwards drawn succes- sively through a great number of little round holes, of a wire- drawing-iron, each less than the other, till it is sometimes no bigger than a hair of the head. GoLD Wire, flatted, is the former wire flatted between two rollers of polished steel, to fit it to be spun on a stick, or to be used flat, as it is without spinning, in certain stuffs, laces, embroideries, &c. Gold Thread, or Spun Gold, is flatted gold wrapped or laid over a thread of silk, by twisting it with a wheel and iron bobbins. ºr GoLD Beating. A quantity of pure gold being melted and formed into an ingot, reduced, by forging, into a plate about || the thickness of a sheet of paper; the gold-beaters cut the plate into little pieces about an inch square, and lay them in the first or smallest mould to begin to stretch them; after they | have been hammered here a while with the smallest hammer, they cut each of them into four, and put them into the second mould, to be extended further. out of which they are taken, divided into four as before, and laid in the last or finishing mould, where they are beaten to the degree of thinness required. They take them out of the mould, and dispose them into little paper books, prepared with a little red bole for the gold to stick to ; each book ordinarily contains 25 gold leaves. Gold, Burnished, that smoothed or polished with a burnisher. GoLD, Mosaic, that applied in pannels on proper ground, distributed into squares, lozenges, and other compartments, part whereof is shadowed, to heighten or raise the rest. GoLD, Shell, that used by the illuminers, for writing gold letters. It is made of leaf-gold, reduced into an impalpable powder, by grinding on a marble with honey. After leaving it to infuse some time in aquafortis, they put it in shells, where it sticks. To use it, they dilute it with gum-water, or soap- Water. GoLD, Pure, that purged by fire of all its impurities, and all alloy. The moderns frequently call it gold of 24 carats. Gold of 22 carats has one part of silver, and another of copper; that of 23 carats has half a part (that is, half a twenty-fourth) of each. GOLDEN NUMBer, in Chronology, a number shewing what year of the Metonic, or lunar cycle, any given year is. To find the golden number, add 1 to the given year, and divide the sum by 19; what remains will be the golden number; unless 0 remain, for then 19 is the golden number. The discovery of the Metonic cycle exhibited such extensive astronomical know- ledge, that it obtained great success and reputation in Greece, insomuch that the order of the period was engraved in letters of gold; whence it acquired the name of golden number. Upon taking them hence, they | out them again into four, and put them into the third mould, Golden Rule, the name usually given by arithmeticians to the Rule of Proportion, or Rule of Three, on account of its extensive usefulness. - GOLDSMITH, or SilversMITH, an artist who makes ves- sels, utensils, and ornaments, in gold and silver. The work is either performed in the mould, or beat out with the hammer, or other engine. All works that have raised figures are cast in a mould, and afterwards polished and finished: plates, or dishes, of silver or gold, are beat out from thin flat plates, and tankards and other vessels of that kind are formed of plates, soldered together, and their mouldings are beat, not cast. The goldsmith is to make his own moulds, and for that reason ought to be a good designer, and have a taste in sculpture: he also ought to know enough of metallurgy to be able to assay mixed metals and to mix the alloy. GONDOLA, a sort of barge, curiously ornamented, and navigated on the canals of Venice. The middle-sized gon- dolas are upwards of thirty feet long, and four broad; they always terminate at each end in a very sharp point, which is raised perpendicularly to the full height of a man. GONG, in Music, a Chinese instrument made of an alloy of twenty parts tin and seventy-eight copper, which is brittle, and malleable when it is tempered, and can accordingly be wrought easily; but it becomes hard, elastic, and brittle, when it is allowed to cool in the open air. It is made in the first of those states, and is afterwards rendered elastic and hard. If struck with a hard body it would break; but if struck with a piece of leather, the sound is at first very small, but by vibration it is communicated to the rest of the mass, and becomes a very loud and terrible noise. GONIOMETER, an instrument for measuring angles of crystals, &c. The simplest of these is a semicircular scale of degrees AA, and a small pair of nippers B B B B destined to receive the crystal, or other body of which the angle is to be measured. The centre is made moveable, so as to permit the legs B B and B C B to be lengthened or shortened by means of the perforation. The crystal to be measured is applied be- tween the compasses, which being thus set, are applied to the semicircular scale, and the value of the angle may be read off at its edge. Hence in the figure it is set at 30°. GONIOMETRY, is a method of measuring angles with a pair of compasses, and that without any scale whatever, except a semicircle. GONIUM, in Natural History, a genus of the vermes infu- Soria, a worm very simple, flat, angular, and invisible to the naked eye. There are five species, of which G. pectorale is found in pure water; molecules oval, nearly equal in size, set in a quadrangular membrane like diamonds in a ring, the lower ones larger than the rest. GOOD BEHAviour, in Law. Surety for good behaviour, is the bail for any person's good conduct for a certain time; as surety for the peace is a recognizance taken by a competént judge of record for keeping the king's peace. Justices of the peace, may also bind persons of evil fame to their good behaviours. GOOGINGS, certain clamps of iron or other metal, bolted on the stern-post of a ship, whereon to hang the rudder, for which purpose there is a hole in each of them to receive a cor- respondent spindle, bolted on the back of the rudder, which G O S. G O S DTCTION ATRY OF MECHANICAL SCIENCE: 405 turns' thereby as upon hinges. There are generally four, five, or six googings on a ship's stern-posts and rudder, according to her size, and upon these the rudder is supported, and tra- verses from side to side as upon an axis. See the article HeLM. . GOOSEBERRIES. For culinary purposes gooseberries are generally employed before they are ripe; but this is founded on erroneous notions of their chemical properties, since, either for sauces or wine, though they are more cool and refreshing, they do not possess the delicate flavour and rich saccharine qualities which are inherent in the ripe fruit. Wine made of gooseberries has great resemblance to Champaigne. In the making of wine, after the juice has been expressed, it is cus- tomary to throw away the skins of the fruit. These, however, may with advantage be employed in distillation, as they afford an agreeable spirit somewhat resembling brandy. When kept a few months, this spirit is said to be little inferior, either in strength or flavour, to the best Cogniac brandy. , Vinegar may be made from gooseberries. Some of the kinds are bottled while green, and kept for winter use; and others are, for the same purpose, preserved with sugar. Gooseberries vary much in colour, size, and quality. Some are smooth, and others hairy. Some are red, others green, and others yellow or amber-coloured. Wild gooseberries are greatly inferior in size to those which are cultivated in gardens. - GOOSE-NECK, a sort of iron hook fitted on the inner end of a boom, and introduced into a clamp of iron or eye-bolt, which encircles the mast, or is fitted to some other place in the ship, so that it may be unhooked at pleasure. - Goose Wings of a Sail, the clues or lower corners of a ship's main-sail or fore-sail, when the middle part is furled or tied up to the yard. The goose wings are only used in a storm, to scud before the wind, when the sail, even diminished by a reef, would be too great a press on the ship in that situation. . GORDIUS, Hair Worm, a genus of the vermes intestina class and order. There are five species. G. aquaticus is from four to six inches long, of a pale brown colour, and darker at || the extremities: it is found in stagnant waters, and twists itself into various contortions and knots; if handled without caution, it will inflict a bite that occasions the whitlow. GORING, or Go RING-Cloth, that part of the skirts of a sail where it gradually widens from the upper part or head, towards the bottom or foot; the goring-cloths are, therefore, those which are cut obliquely and added to the breadth. See the article SAIL. GOSSAMER, the name of a fine filmy substance, like cob- web, scen to float in the air in clear days in autumn, is probably formed by the flying spider, which in traversing the air for food, shoots out these threads from its anus, which are borne down by the dew, &c. GOSSYPſ UM, or Cotto N, a genus of the polyandria order, in the monadelphia class of plants, and in the natural order of columniferae. See page 198 for a description of Cotton. In warm countries cotton plants are cultivated in great quantities in the fields, for the sake of the cotton they produce ; but the first species is most generally cultivated. The pods are some- times as large as middling-sized apples, closely filled with the seed surrounding the cotton. - It is impossible to ascertain with precision the actual amount of any of the great manufactures of the kingdom ; but of cot- ton it may be safely asserted, that the value is from thirty to forty millions of pounds sterling per annum. The average annual amount of cotton-wool imported during the last seven years was 145,000,000 lbs., from which deduct 15 millions for exports, and 10 millions for cotton-wool used at home in an unmanufactured state, 120 millions remain. Taking the price of this wool at Is. per lb., and the increase of value by manu- facture at five times the cost of the raw material, the amount will stand thus:– - 120,000,000 lb. of cotton at 1s. per lb. £6,000,000 Increased value by manufacture. . . . . . 30,000,000 - Gross amount. . . . . . ——— £36,000,000 Average value of cotton manufactures exported... 16,560,379 -*me -- - Home consumption. . . . . . £19,439,621 This result is not very dissimilar to the statement made by the president of the Board of Trade in the House of Commons, *** on the 8th of March, 1824, that the annual value of cotton goods manufactured had risen to the incredible amount of £33,337,000. - - - : Every part of the cotton trade, from the importation of the raw material to its completion' by the weaver, the bleacher, the dyer, and the calico printer, is carried on in Lancashire, but the branch for which Manchester is chiefly distinguished is the spinning. In this department of the trade there are at pre- sent (August, 1826) 104 spinning factories in the townships of Manchester, Chorlton-row, Ardwick, Salford, Pendleton, and Hulme, worked by 110 steam-engines; of the aggregate power of 3598 horses. In the year 1787, the number of spinning factories in the county of Lancaster amounted only to 42, and those were in general of a magnitude very inferior to the mills which at present exist in this place. - From a calculation made in 1817, it appears, that the num- ber of persons then employed in the spinning of cotton in this country was 110,768; that the aid they derived from steam was equal to the power of 20,768 horses; and that the number of spindles in motion was 6,645,833. By this immense process 3,987,500,000 hanks of cotton yarn were produced yearly, taking the average at 40 hanks to the pound ; and the quantity of coal consumed in their production is stated at 5000 tons. Raw cotton converted into yarn in the United Kingdom in 1817, ....... . 110,000,000 lb. Loss in spinning estimated at 13 oz. per pound. . . . . . . . . . . . . . . . . . .... 10,312,500 Quantity of yarn produced, ... — Number of hanks, taking the average at 40 per lb. . . . . . . . . * * * * * * * * * * * * * * * tº e º e s - e º ºs e - 3,937,500,000 lb. Number of spindles employed, each spindle being supposed to produce two hanks per day, at 300 working days in the year, . . . . Number of persons employed in spinning, supposing each to produce 120 hanks per . day, . . . . . . . . . . . . . . . . . • ? - - - - - º “º e º º E tº dº e g ºf 110,763 Horse power employed, equal in number to 20,768 Four ounces and a half of coal estimated to produce one hank of No. 40; and 180 lb. of coal per day, equal to one-horse power. - . 99,687,500 lb. 6,645,833 The increase of manufactures since 1817 has been consider- able, certainly not less than 20 per cent. as will appear from the increased average annual quantity of cotton wool imported. The number of men employed in 1825, in one branch of the cotton manufacture in Great Britain, viz. in cotton twist spinning, amounts to 250,000, and these men, aided by the power of water and steam, as first movers to machinery, spin as much thread as could have been spun before the introduc- tion of such machinery by the hands of 24 millions of men; and this calculation respecting the power of machinery is supported by a fact otherwise inexplicable ; namely, that cotton wool grown in Hindoostan, is imported into Britain, where it is manufactured, and afterwards returned to Hindoostan, and sold there at prices ruinous to the Indian manufacturer, although his workmen are contented with the slender wages of two-pence a day ! About four-fifths of the whole amount of the cotton trade of the kingdom centres in the county of Lancaster; and it is calculated that the capital employed in Lancashire in this trade alone, in buildings and machinery, amounts to £8,000,000. Steam, it has been already observed, is now applied to a con- siderable extent in the weaving as well as in the spinning ; and we have ascertained, that there are at present (July 1825) in the parish of Manchester alone, upwards of 20,000 steam looms in motion. In Mr. Guest’s book on “The Cotton Manufac- tures,” the number of steam or power looms in Great Britain were estimated at 10,000; that estimate was even too low, and the probability is, that there are now in England and Scotland not fewer than 40,000 power looms employed in the weaving of cotton alone, 8000 of which are in Scotland. GOTHIC STYLE, in Architecture. The characteristics of this manner of building are pointed arches, greater height than breadth in the proportions, and profuse ornament, chiefly derived from an imitation of the leaves and flowers of plants. See ARCHITECTURE. - 5 L 406 G. G. W. G O V DIGTIONARY OF MECHANICAL SCIENCE. GOUGE, an instrument; or tool used by divers artificers, , being a sort of round hollow chisel for cutting holes, &c. either in wood or stone. - . . . . . . . . . . GOUGING, is the name given to a barbarous practice in the southern states of North America, where two men fight, and endeavour with their thumbs to scoop out each other’s eyes. GOVERNMENT, in general, is the polity of a state, or an orderly power constituted for the public good. Civil govern- ment was instituted for the preservation and advancement of men's civil interests, and for the better security of their lives, liberties, and properties. . The various forms of government may be reduced to one of these heads; either the civil autho- rity is delegated to one or more, or else it is still reserved to the whole body of the people; whence arises the distinction of government into monarchy, aristocracy, and democracy. A mixed government is composed by the combination of the simple forms. The government of this country is a mixed government, being formed by a combination of the three regu- lar species: the monarchy residing in the king, the aristocracy in the house of peers, and the republic being represented by the house of commons, so as to unite the advantages and ex- clude the inconveniences of the several simple forms. The executive power of the laws being lodged in a single person, they have all the advantages of strength and despatch that are to be found in the most absolute monarchy, and the legislature of the kingdom being intrusted to three distinct powers, entirely independent of each other, and actuated by different springs, and attentive to different interests, there can be no inconvenience attempted by either, but will be understood by one of the other two. . . . . . . . . . . . . . . . . . * GOVERNOR, a contrivance for equalizing the motion of mills and machinery. When any part of the machinery of a mill is suddenly stopped, or suddenly set going, and the mov- ing power remains the same, an alteration in the velocity of the mill will take place; and it will move faster, or slower. Every machine having a certain velocity at which it will work to more advantage than at any other, the change of velocity arising from the foregoing-cause, is in all cases a disadvantage, and in delicate. operations exceedingly hurtful. In a cotton- mill, for instance, which is calculated to move the spindles at a certain rate, if from any cause the velocity is increased, a loss of work immediately takes place, and an increase of waste from the breaking of threads, &c.; on the other hand, there must be an evident loss from the machinery moving slower than is necessary. - -- • In steam-engines this evil is remedicd by a contrivance called a Governor, (see the Plate, fig. 1.) Two balls are fixed to the ends of rods, in continual revolution, and as soon as the motion becomes a little too rapid, the balls rise considerably, and, by the intervention of a lever, act upon a throttle-valve, which diminishes the quantity of steam admitted, and of course serves to make the motion less rapid. The Steam-engine Governor.—I K, fig. 1, represents a spin- dle kept in motion by the engine; A, B, the centrifugal balls; C A, and C B, the rods which suspend the balls. These rods cross one another, and pass through the spindle at C, where the whole are connected by a round pin put through the spin- dle and the rods at C, which serves as the point of suspension for the centrifugal balls or revolving pendulum. A part of the spindle above C, is square, and nicely polished, so that the piece of brass, M, may slide easily upon it. The piece of brass # , º a “ ” M is round on the outside, and has an external groove turned . the upper end of it to receive the lever NO, whose ful- efum is at P. This piece of brass is connected with the ball- rods by two short pieces and joints DE, FG. The construction of steam-engine governors sometimes differs a little from that now described ; but if this construction be understood, there will be no difficulty in comprehending any other. ...Operation.—When the engine goes too fast, the balls fly off from the spindle, and depress the end, N, of the lever, which partly shuts the throttle-valve, and diminishes the quantity of steam admitted into the cylinder; and, on the other hand, when the engine goes too slow the balls fall down toward the spindle, and elevate the end N of the ſever, which partly opens the throttle-valve, and increases the quantity of steam admitted into the cylinder. - old lift-tenters. Governor for a Wind-mill.–In a wind-mill, when the velocity is increased by the irregular action of the wind, the corn is sometimes forced rapidly through the mill without being suffi- ciently ground. There is a contrivance for preventing this, (similar to the governor of a steam-engine, but which was much earlier in use,) and called in some parts of England a lift- tenter. By means of the centrifugal force of one or more baſis, which fly out as soon as the velocity is augmented, and allow a lever to rise with them, the upper mill-stone is made to descend, and bring it a little nearer to the lower one. This machine, says Dr. Gregory, is curious, and might perhaps in other cases be usefully applied. We shall, therefore, describe two constructions on the same principles. First Construction of Lift-tenters for Wind-mills.-This ma- chine, and part of the stone-spindle and framing with which it is connected, are represented in the Plate, fig. 3. To the stone-spindle there are fixed four arms A, A, A, A.; and there are four similar arms B, B, B, B, firmly attached to the hollow cylinder C, which is loose on the spindle FG. The pendulums D, D, D, D, are hung above, to the arms A, A, A, A, and through holes toward their lower extremities pass the arms of the loose cylinder. When the mill is at rest, the pendulums hang ver- tically; but, by their centrifugal force, when the mill is in motion they hang obliquely; and that obliquity is increased in proportion to the velocity, and proportionately raises the loose cylinder C. This cylinder C acts on the one end of the lever E, which has a connexion with the clove upon which the bridge of the stone-spindle rests, and accordingly raises or depresses the upper mill-stone in proportion as the wind blows weak or strong. . . . Second Construction.—Another modification of the same prin- ciple (applied above the mill-stones,) but having one pendulum only, is represented by fig. 4, and will be easily understood from what has been said respecting the first construction of the Water-wheel Governors.-Governors are sometimes applied to water-wheels, and made on various constructions. Smiths’ bellows have been applied to that use, the upper board rising or falling in proportion to the velocity of the lower board, which received its motion from the mill. But we shall describe a construction which has for several years been at work in Cartside cotton-mill, erected under the direction of the late Robert Burns, Esq. - - - First Construction.—The principles of this water-wheel governor are nearly the same as those of the steam-engine governor. It has a revolving pendulum which receives its motion from the mill, and in proportion as the machinery moves faster or slower, the centrifugal force acts upon the governor, and raises or depresses an iron cross, which, acting on a lever, reverses the motion by the wheel-work, which ope- rates upon a sluice so as to enlarge or lessen the passage of the water to the water-wheel; this sluice is made on the prin- ciples of the throttle-valve, that it may be moved by a small power. So long as the machinery is moving at a proper velo- city, this wheel-work of the sluice apparatus remains at rest. Fig. 5, represents different views of this machine, and some of its parts detached. The same letter in all the figures refers to the same part. The revolving pendulum EFG H, receives its motion from the mill-work by means of a rope giving motion to a pulley I. The upright shaft M. N, is kept in constant motion by the wheel-work O PRS. The wheel N acts constantly into the two bevelled wheels T and U, and makes them move in contrary directions. They are loose on the shaft when the mill is going at its proper speed. But if the mill moves either too fast or too slow, the one of these wheels, by means of a clutch Q, in a way to be described, is connected with, and carries round, the lying shaft DC, and, by a pair of bevelled wheels, communicates motion to the oblique shaft B W, which again, by a screw X, and quadrant-wheel Y, moves the sluice Z, and, by making it stand more or less oblique, alters the area of the passage for the water. From inspecting fig. 5, No. 1, it will appear evident that the box a, will be raised, or depressed, in proportion as the balls E and F, of the revolving pendulum EFG H, are removed fur- ther or brought nearer to the centre of motion; for when the velocity is greatest, the balls E and F, by their centri- a ſºlo (*** * * *-iſºn ºwn, 1/w//www. - - __ ºne-anºn. ºn 2 - P I ºvatiºn. M T. o ſº-ºn - ºn-ºil– T ** 5.Nº.3. - - b lº Pan of ſºrts on a larger scale. º - t - --- - - - º, º Aº ºf ºvatiºn ºr /arts ºwed º - º º º - º, º G. R. A G R A DICTIONARY OF MECHANICAL science. 407 fugal force, will extend themselves furthest from the centre of motion, and raise the box a. See also fig. 5, No. 2, No. 3, and No. 4. To the box a, is fixed a cross b c. There is a forked lever d qe, the fulcrum of which is at f, and which turns hori- zontally. This forked lever has four prongs, 1, 2, 3, 4, repre- sented distinctly in No. 3. When the mill is at its proper speed, the cross works within the prongs 1 and 2; in this situ- ation of the forked lever, the clutch Q is disengaged from both the wheels T and U, and they move on their bushes with- out carrying round the lying shaft. See No. 2. The clutch is made to slide on a part of the shaft which is square. When the mill moves too quick, the cross gland is raised, and, in turning round, hits the prong 3, which immediately causes the lever to throw the clutch into the arms of the wheel U. This wheel then carries the clutch and shaft round with it, and by the means already described, acts on the sluice, and by lessen- ing the quantity of water falling on the wheel, diminishes its velocity. On the other hand, when the mill goes too slow, the cross is depressed, and, striking the prong 4, reverses the motion of the shaft, and so produces a contrary effect on the sluice. Moreover, the train of wheel-work is so calculated as very much to reduce the motion at the sluice, and this is found from experience to be necessary. Were the area of the aper- ture too suddenly changed, the effect on the water-wheel would be too violent. Every time the mill is stopped, it is proper to lift the wheel R. out of gear. The centre on which the sluice turns should be one-third of its height from the bottom, in order that the pressure of the water above the centre may balance that below. At m there is an upright shaft, which is worked by hand when required. Second Construction of the Water-wheel Governor.—Fig. 6, re- presents a sluice regulator as executed in some parts of Eng- land. It differs little from that already described, only that the lying-shaft A B receives its motion immediately from the mill, instead of from the axle of the revolving pendulum, as in the first construction. From having so minutely described that construction, the attentive reader will find no difficulty in com- prehending fig. 6, from inspecting the Plate. See Buchanan’s Essays on Mill Work. GRACE, in Music, either in vocal or instrumental per- formances, consists in giving due place to the decorative addi- tions, and that easy, smooth, and natural expression of the passages which best conveys the beauties of the composition. GRACE, Days of, three days immediately following the time of payment of a bill, within which the creditor must protest if payment is not obtained, in order to entitle him to recover the amount by legal proceedings against the drawer, acceptor, and indorser—one or all. GRACULA, the Grakle, a genus of birds of the order picae, There are 13 species, of which we shall notice the following: G. kelegiosa, or the minor grakle, is of the size of the black- bird, is found in the East Indies, is rendered familiar with the greatest ease, and taught to speak with greater facility than even the parrot, and also enounces its words with more dis- tinctness. It feeds on berries and fruits, and is particularly partial to cherries. The paradisaea tristis is rather larger than the former, and inhabits the Philippine islands. It is exceed- ingly voracious, and has been known to swallow a young rat nearly two inches long, after beating it against the wires of its cage to soften it. GRADUATE, one who has taken a degree in an university. GRADUATION, in Mathematics, the act of graduating or dividing any thing into degrees or equal parts. GRAFTING, in Gardening, inserting a scion or shoot of a tree into another, so as to make it yield fruit of the same nature with that of the tree from which the graft was taken. The ope- ration is performed in the following manner: cut off the head of the stock at the proper height, and in a fair part of the bark, making a smooth flat top. The most proper size for stocks is from half an inch to an inch in diameter. Dwarf trees are to be grafted within six inches of the ground, and standards as high as the stock will bear, considering whether they are to be half or full standards. The scions should be healthy and strong, and taken from the outsides of fruitful trees, where the juices of the wood have been properly digested by sun and air; they should be taken from trees just in their prime, or at fuli bearing, and not before. Let them be cut two or three weeks sooner than wanted. The middle of scions is fittest for the purpose ; but do not cut off the tops till they are brought out to graft, for they keep best in length. Take off a little of the lower end of the scion first, and then cut it in length so as to have three or four eyes to appear above the claying. The time for grafting is usually from mid-February to mid-March; but |. a forward season sooner, and in a backward one sometimes ater. Cleft-grafting has been the most common method. The stocks for this mode should be strong, about three-quarters of an inch diameter, or more; but it may be used with very young stocks, having scions of like thickness. Cut off the head, so as to have (on the sunny side) a smooth part in the stock, where the scion is to be placed, and cutting a part of the stock off slopewise, opposite to this place, leave the top or the crown of the stock about half an inch wide. Then cleave the stock with a strong knife, or thin sharp chisel, about two inches deep, as near the middle as possible, so as not to divide the pith, and if any roughness appears in the slit, smooth it off with a penknife; but something of the wedge kind must be put into the slit to keep it open to receive the scion, leaving pro- per room to put it in. Cut the scion on each side to the form of a wedge at bottom, an inch or more long, making that side which is to be placed inwards in the stock, thinner by about one-third. Put the scion in, so that its bark and that of the stock may be level; and, consequently, that the two barks may unite and run into each other; for on this one principle depends the whole art of grafting. The graft must be nicely whipped round with wet bass pulled tight, and the whole clayed over to an inch above, and half an inch below, smooth- ing it off taper with a trowel or knife dipped in water. Whip-grafting has the advantage of cleft-grafting in meat- ness, and not requiring the stocks to be so old by a year or two, as very small ones will do; for the stock is directly covered by the scion, and it takes with certainty if properly performed. Having cut the head of the stock off, and the scion to its proper length, slope the lower end of the scion about an inch and a half, and to a point: then cut the stock to answer it, bark against bark, and tie them together exactly to their place, and clay it. Grafting in the bark, or crown-grafting, is a good way both for ease of operation and certainty of success; but it will hardly suit any other fruit than apples or pears. The head being cut off, make a straight slit down and through the bark from the top, at the place destined for the graft, nearly as long as the slope cut off the scion, which may be one and a half or two inches. Loosen the bark a little at the top of the score, and them with some smooth instrument of dry hard wood, ivory, bone, or silver, rather than iron or steel, open the bark sufficiently to receive the scion. This instrument should be thin, tapered, and rounded towards the point, to suit the shape of the scion’s face ; one side of it flat, and the other a little convex, the flat side being applied to the wood of the stock; let it be rather narrower than the scion, that it may not loosen the bark too wide. Cut a bit of the bark of the scion smooth off at the bottom, that it may not turn up in pushing down. It will be proper to cut the scion with a small shoulder, to rest upon the stock, score the bark on each side the scion, so that it may fall close to the stock, and to the edges of the scion. Bind and clay. This way of grafting is used most properly with strong stocks; and sometimes is applied to large branches. and even trunks of old trees, to change the sorts or renew the wood. Side-grafting is done in the bark, much like inoculation, a scion being inserted instead of a bud; but there must be a fluent sap first, i. e. the bark must part readily from the wood before this mode of grafting is attempted. The head of the stock is not to be cut off, only thinned a little if it is too large and the side shoots taken away. The bark of the stock, where the insertion of the scion is to be, must be cut through in the form of the letter T, as wide and as long as is sufficient to receive the scion, cut as before, with a slope face of at least an inch long, taking advantage (if it may be) of a part of the stock that is a little gibbous. Let the bark of the stock be neatly raised to receive it, but yet no more than necessary; a 408. G R A G. R. A DICTIONARY OF MECHANICAL SCIENCE." little bit of the bark may be sliced off the part that is over the cross cut, to receive the scion the better. - Approach-grafting, or Inarching, is performed in April or May. When the stock we would graft, and the tree we would propagate, grow near together, bend the best-situated young branch of the tree or shrub to be propagated, to the stock to be grafted, and having determined on the part at which most conveniently to fix the shoot, cut the bark of that part of the shoot off, with nearly half the wood (not to touch the pith) to the length of about three inches for a strong branch, or less for a weaker. Then cut exactly so much of the bark and branch of the stock off, as will receive the cut part of the branch or shoot, so as to bring bark and bark in contact in every part, and if the contrivance of lipping is used, it will secure them better together. Bind and clay, and tie the work so that the wind may have no power over it. Budding, or Inoculation, is the most considerable mode of propagation. It is performed as soon as good shoots with good eyes of the present year can be had, so that the season may be reckoned from mid-June to mid-August. Peaches and nectarines are propagated on plum-stocks. Plums and cher- ries may be inoculated on sucker stocks of any kind. Pears, if for standards, should be inoculated on pear-stocks, and on those raised from seed rather than suckers; but if for dwarfs, quince-stocks may be best used, to keep the trees from grow- ing off too fast. Let the scions for inoculation be taken only from the outside branches of healthy and fruitful trees, but the buds must not be cut from the upper part of the scions. Before the buds are prepared, get the stock ready to receive them, by taking off lateral shoots, leaving an uncut single stem. At the part fixed on for the inoculation (which should be smooth, and rather on the north side) cut the bark through to the wood in form thus, T, the cross and the down-slit being of the length necessary to take in the bud, which may be cut with from one to two inches of bark; putting the point of a knife (or some other instrument, rather not of iron or steel) into the top of the down-cut of the stock, raise the bark all the way to the bottom, so that it will just receive the bad easily. There are knives Inade on purpose for budding, with flat ivory hafts. To pro- cure proper buds, put your knife in (suppose) about three- fourths of an inch above the eye, and with a slope downwards cut the scion half through, then do it at the same distance below the eye, and sloping it upwards cut up the middle of the wood, till the knife meets the upper incisions, so the eye, or bud, will be directly in the middle. Then separate the wood from the bark, which is to be done thus: with your nail, or the point of a knife, loosen the bark at the top, and strip it from the wood ; or rather with a swan or large goose quill, made in the form of an apple-scoop, (having a regular smooth edge,) push it down between the bark and wood, pressing it against the wood. Examine the inside of the bark, and if there is a cavity just behind the eye or bud, it is good for nothing. The leaf that grows by the eye is to be cut down to near its footstalk. See that the bark of the stock is loosened a proper length and breadth, and if, when the bud is put in, it should prove a little too long, cut the spare part off; so that the top of the bud being squared. falls in straight with the cross cut of the stock. Thus fixed, bind it moderately tight in its place with wet bass, beginning at the bottom, and passing by the bud, go on to the top, or rather above it. Care must be taken that the bud is not hurt, and it is to be left only just starting out between the bass. If the buds have taken, it will be seen in about three weeks or a month, by their appearing fresh and plump. As often as any shoots appear below the budding, cut them off, and also some of the shoots above, if there are many of them : for it is not proper that an inoculated stock should have a large head. In a month loosen the bandage, by taking it off, and putting it on gently again for another month. In March, cut the head of the stock off with a keen knife, close behind the budding, in a sloping direction.—Watkins's Cyclopædia. GRAIN, the name of a small weight, the 20th part of a scruple in apothecaries’ weight, and the 24th of a penny weight troy. A grain-weight of gold-bullion is worth about two-pence, and that of silver half a farthing. GRAIN also denotes the component particles of stones and metals, the veins of wood, &c. - - GRAIN and Seeds are composed chiefly of starch or coagu- lated mucilage, generally combined with gluten, oil, or albu- minous matter; in corn with gluten, in peas and beans with albuminous matter, and in rapeseed, hempseed, linseed, and the kernels of most nuts, with oils. Sir H. Davy found in 109 parts of wheat sown in autumn, of starch, 77; of gluten, 19. In 100 parts of wheat sown in spring, of starch, 70; of gluten, 24. In 100 parts of Barbary wheat, of starch, 74; of gluten, 23. In 100 parts of Sicilian wheat, of starch, 75; of gluten, 21. GRALLAE, in Ornithology, is an order of birds in the Lin- naean system, which includes 20 genera, viz. the phaenicopterus, platalea, palamedea, mycteria, tamtalus, ardea, corrira, recur- virostra, scolopax, tringa, fulica, parra, vaginalis, psophia, cancroma, rallus, scopus, glareola, haematopus, and cha- radrius. . GRAMMAR, is the art of speaking and writing a language correctly; and the purpose of language is to communicate our thoughts. + In English there are ten parts of speech, namely, the noun, the article, the adjective, the pronoun, the verb, the participle; the adverb, the preposition, the conjunction, and the inter- jection. - A moun, or, as it is sometimes called, a substantive, is the name of any person, place, or thing, as James, London, land, leisure. - - - An article is a word prefixed to nouns, to point them out, and to shew how far their signification extends. . The articles are a, am, the ; the is definite ; a and an indefi- nite : thus, we say the house, when we mean any particula house ; a house, when we refer to one generally. . A noun may be known by taking an article before it, as a book, an owl, the moon; or by its making sense of itself, as virtue, poverty, wealth. . . . Nouns are either proper or common:—proper nouns are the the names appropriated to individuals, as Charles, Paris, Thames; and common nouns denote the species of things, as a man, a city, a river; thus Paris is a proper noun, being a name appropriated to a particalar city; but city is a common noun, as understood of any city. * All nouns are of the third person when spoken of, and of the second when spoken to. Examples. The men ºwn ; trees are green; here men and trees are spoken of, and are of the third person:—men and citizens, listen to my words ; in this case men and citizens are spoken to, and are of the second person. To nouns belong person, gender, number, and case. * Gender is the distinction of nouns with regard to sex; there are three genders, the masculine, feminine, and neuter. The masculine gender denotes animals of the male kind, as a man, a horse, a bull. The feminine gender indicates animals that are females, as woman, cow, mare. But the neuter gender signifies objects neither male nor female, as pen, paper, book. Number. There are two numbers belonging to nouns, the singular and the plural. The singular is used to express one object; and the plural is used when two or more are to be expressed. & The plural is generally formed, (L.) By adding s to the sin- gular, as river, rivers. (2.) By adding es when the singular ends ch, s, sh, æ, and 2, as church, churches; kiss, kisses; lash, lashes; fow, foxes. (3.) By changing the terminations of nouns ending in f or fe into ves, as calf, calves ; knife, knives. (4.) When mouns end in y, the plural is formed by changing y into ies, as fly, flies. There are many exceptions to these general rules, as or, oxen; muff, muffs; chief, chiefs; key, keys; goose, geese ; foot, feet, &c. Some nouns admit of a singular termination only, as wheat, steel, sloth: some have the plural termination only, as bellows, scissars, ashes ; and in some nouns the singular and plural are the same, as deer, sheep, &c. ſº Case is the variation of nouns, serving to express the differ- ent relations they bear to each other. e - tº * English nouns have three cases, the nominative, the possessive, and the objective. tº * - The nominative expresses the name of a thing, on the subject of the verb ; as the boy runs. ge ſº The possessive denotes property or possession, and is formed G. R. A G. R. A 409 Diction ARY of MECHANICAL science. * by adding s to the nominative, with an apostrophe before it, as Solomon's wisdom, the cow's crib. When the moun ends in s, the apostrophe only is added, as the Stationers' arms. The objective case denotes the object of an active verb, or of a - proposition; as, Charles teaches James; Charles and James Hive in London. Nouns are declined thus: Nominative. Man. Men.' Possessive. Man's. } Singular. Men's. S. Plural. * Objective. ‘Man. - . Men. $ - The nominative and objective are spelt alike; but in a sen- tence the nominative comes before the verb, and the objective after a verb active, or preposition. - - , Adjectives. An adjective is a word added to a substantive, to denote its quality, or property, as white paper, black ink, i green grass. Adjectives change their terminations to augment or diminish the quality of the noun; and these changes are called degrees of comparison. There are three degrees of com- parison, the positive, as BRAVE ; the comparative, as BRAVER ; and the superlative, as BRAvest. The positive is changed into the comparative by the addition of r, or er; as wise, wiser; hard, harder; and into the superla- tive by adding st or est; as wise, wisest; hard, hardest. . The words more and most, placed before an adjective, have the same effect, as more wise, most wise. Monosyllables are, for the most part, compared by er and est; as hard, harder, hardest ; and dissyllables by more and most ; ; as modest, more modest, most modest. i Some adjectives are compared very irregularly, as Good, better, best. Many, more, most. Little, less, least. Bad, worse, worst. Some comparatives form the superlative by adding most, as fore, former, foremost ; wſp, whner, wrºpermost ; and some adjec- tives have only two degrees of comparison, as under, undermost. Promowns. A pronoun is a word used as a substitute for a noun, and there are three sorts of pronouns; the person AL, as I, thou, he , we, ye, they : the RELATIVE, as who, which, what ; and the ADJECTIVE, as some, other, any, one, all, such. - The third persons singular of the personal pronouns, he, she, and it, admit of gender; and pronouns, like nouns, have three cases, the nominative, possessive, and objective. They are mostly different from each other. - Singular. Plural. First person. Nom. ſe We Poss. Mine. Ours Obj. Me. U.S. Second person. Nom. Thou. Ye or you. Poss. Thine. Yours. - Obj, #. You. Third person. Nom. He, she, it. : -- f Poss. #3". theirs, Obj. Him, her, it. . CIR), In pronouns the first person is the speaker; the second is the person spoken to ; and the third is the person spoken of Relative pronouns are such as relate to some word or phrase going before, which is called the antecedent; these are, who, which, and that. Who is applied to persons, which to animals and inanimate things. That is applied both to persons and things. - What is a compound relative, and is equivalent to that which. “This is what I wished,” that is, “the thing which I wished.” Who, which, what, are called interrogatives, when used in asking questions. The cases of who are, Nom. Who. Poss, Whose Obj. Whom. Adjective pronouns are either possessive, distributive, de- monstrative, or indefinite. The possessive are those that relate to possession, or pro- perty: these are my, thy, his, her, our, your, their. The distributive pronouns are those which denote the persons or things that make up a number, as taken separately and singly: these are each, every, either. The demonstrative pronouns are those which point out the subjects to which they belong ; as this and that; these and those. The indefinite are those which express their subjects in an indefinite or general manner, as some, other, any, one, all, such. The Verb. A verb is a werd that expresses action, passion, stiffering, or a state of being, as I write, I am beaten, I am. And 43. verbs are either active, transitives, as I dig the ground, or neuter, as I run, or auxiliary, as I am. . A verb transitive supposes a person or thing that acts, and a person or thing that is affected by the action; thus, I dig the ground, there is the person who acts, and the ground acted upon. The person or thing that acts is called the agent, and the person or thing acted upon is called the object ; as when we say, Alexander conquered Darius; Alexander is the agent, and Darius the object. A verb transitive supposes an agent and an object:—a verb intransitive implies an agent, and has no object, as I walk; but it may be followed by a noun of the same signification, as I run a race. - To find the agent of a transitive verb, we ask the question, who, or what, before the verb; as Who conquered Darius? answer, Alexander, the agent. To find the object, you ask the question, Whom did Alexander conquerº answer, Darius, the object. The radical form of verbs, or that from which all the modifi- cations of them are derived, is that in which they follow the particle to ; as to love, to run. The auxiliary, or connecting verbs, are, am, are, be, become, is, was, were ; and they serve to connect qualities with their sub- jects, or are used in conjunction with other verbs; as I am cold; John and James are going to London ; God is good. The person or thing preceding a connecting verb is called the subject, and a quality or thing coming after it is called the predicate. - The properties of verbs are mood, tense, number, and person. Mood expresses the sense of the verb, and there are four moods, the indicative, imperative, subjunctive, and infinitive. The indicative merely declares a thing, as I walk ; does he walk? The imperative expresses a command, &c. as run into the village ; copy this writing. - - * The subjunctive expresses a thing conditionally, and is pre- ceded by a conjunction: I will love him, though he reprove me. Were he more kind, he would be more amiable; that is, if he were more kind, &c. - The infinite mood is preceded by the preposition to, and is not limited by person or number; as to act, to run, to be loved. . The tenses mark the division of time; they are, (1.) The present, expressing the time now: (2.) The perfect, expressing time past: (3.) The future, expressing time to come. In verbs there are two numbers, singular and plural, and three persons, viz. first, second, and third, singular and plural, answering to the pronouns, I, thou, he , we, ye or you, they. All words whatever, except I, thow, we, ye or you, are of the third person. - * The second person of the present tense, indicative mood, is formed by adding storest, to the first person, as love, lovest ; walk, walkest, according as the verb has, or has not, the final e. In the plural number there is no change; as we love; ye or you love ; they love. • The third person is formed by adding to the first th or eth ; as love, loveth; walk, walketh ; but th or eth is often changed to s, as he loveth or loves; he walketh or walks. The first and third persons of the perfect tense are formed by adding d or ed, to the first person of the present, according as the verb has or has not the final e : as love, loved; walk, walked. The second person is formed by adding est to the first per- son, which is usually changed into st, as loved, lovedst. The future tense is known by the sign shall or will; as I shall com- plete this work. I will complete it. The imperative mood has only two persons, the second and third, singular or plural, and let is its sign. The subjunctive mood has only two tenses, the present and past, and its signs are may, can, might, could, would, should. The infinitive mood has two tenses, the present, as to write, and the past, to have written, without either number or person. - + Participles are certain forms of the verb, and are so called from participating the active properties of verbs, and the form and construction of adjectives. They are the present, and the past or perfect. - - The present participle is formed by adding ing to the verb, as walk, walking: if the verb end in e, the e is dropt, as love, Ioving ; make, making ; be makes being, and dye, dyeing. 5 M 410 G R A G. R. A DICTIONARY OF MECHANICAL SCIENCE. The perfect participle is formed by adding d or ed to the verb, as love, loved; walk, walked. But there are many excep- tions, as write, written; draw, drawn; bind, bound, &c. The perfect tense, and perfect participle of verbs, having only one syllable, and ending in d or t, are the same as the present; as read, read, having read; hurt, hurt, having hurt. In verbs ending in d, preceded by a diphthong, one of the vowels is dropped in the perfect tense and perfect participle; as bleed, bled, having bled ; feed, fed, having fed. In verbs ending in ing and ch, the perfect tense and perfect participle ends in ght; as bring, brought; teach, taught. Many verbs have the perfect tense and perfect participle ending in t ; as dwell, dwelt; leave, left; pass, past. Auxiliary verbs are used with other verbs to ascertain the time and other circumstances of an action with greater preci- sion; and in forming the tenses, the change of termination is confined to the auxiliary, as I do love; thou dost love ; he doth love, &c. I am loving, thou art loving. An adverb is a part of speech joined to a verb, an adjective, and sometimes to another adverb, to express some quality or circumstance respecting it; as he writes well, a truly benevo- lent man; he fought very bravely. . Some adverbs admit of comparison; as soon, sooner, soonest; and those ending in ly are compared by the words more and most, as godly, more godly, most godly. . Prepositions express the relation that one word has to another; as he went to Cambridge. He walked from London to York in four days. They are supported by industry. Conjunctions join words and sentences together, and shew the manner of their dependence upon one another ; as John and James live in the country. I will run if you wish it. Con- junctions are either conjunctive. as and, or disjunctive, as or. Interjections are broken or imperfect words, denoting some emotion or passion of the mind; as alas ! I dread to hear the news. Oh! how anxious I am Syntaa, treats of the agreement and connexion of words in a sentence. A sentence is an assemblage of words forming a complete sense: the principal parts of which are, the subject, the attribute, and the object. The subject is the thing chiefly spoken of; the attribute is the thing or action affirmed or denied of it; and the object is the thing affected by such action; as, “Alexander pursued Darius;” Alexander is the subject; pursued, the attribute; Darius, the object. The subject is the nominative to the verb, and usually goes before it; and the word or phrase denoting the object follows the verb. “A pru- dent man restrains his passions:” in this case, “A prudent man,” is the subject; “restrains,” the attribute; “his pas- sions,” the object. - Syntax consists, (1.) Of concord, which is the agreement of one word with another, in gender, case, and number. (2.) Of government, which is the power which one part of speech has over another in directing its mood, tense, or case. A verb must agree with its nominative case in number and person; as, “I learn;” “thou walkest ;” “the man runs.” Two or more nouns singular, joined together with a conjunc- tion copulative, have verbs and pronouns agreeing with them in the plural ; as, “Cicero and I are well;” but if the conjunction be disjunctive, the verb will be singular, as, “Thomas or John hopes to be at home.” A noun of multitude may sometimes have a verb or pronoun agreeing with it, either in the singular or plural number, as, “ the multitude eagerly pursue their pleasures;” or, “the mul- titude eagerly pursues its pleasures.” Pronouns must always agree with their antecedents, and the nouns for which they stand, in gender and number; as, “The man whom I respect.” “This is the flower which I admire,” “The boys and girls enjoy their play.” When no nominative case comes between the relative and the verb, the relative is the nominative ; as, “The friends who walked with us.”—When a nominative comes between the rela- tive and the verb, the relative is governed by some other verb; as, “to whom I owe my being ;” here the relative whom is governed by the preposition to. - Every adjective belongs to a substantive expressed or under- stood ; as, “Few are really happy,” that is, few persons. “This is a beautiful plant,” that is, this plant is, &c. - The article a or an agrees with the singular nouns only ; but the article the may agree with singular or plural nouns; as, “the field,” “the fields.” One substantive governs another, signifying a different thing in the possessive case; as, “My brother’s horse.” Transitive verbs govern the objective case; as, “The master instructs me or him.” “A good cause supports us or them.” One verb governs another in the infinitive mood; as, “I am ready to answer him, or her.” : g Participles govern the same cases as the verbs from which they are derived; as, “his friend is weary in admonishing him.” Adverbs are for the most part placed before adjectives, after transitive or intransitive verbs, and frequently between the auxiliary and the verb; as, “He spoke a very long time, and was attentively heard by all the company.” - - Two negatives destroy one another; as, “His manner is not wngraceful ;” that is, “He has a graceful manner.” Prepositions govern the objective case; as, “He spoke well of her.” “I ran by her, or him.” “They will come to us.” Conjunctions connect the same moods and tenses of verbs, and cases of nouns and pronouns; as, “The friend praised and rewarded us.” “The master reproved him and me and her.” Conjunctions that are of a positive nature require the indi- cative mood; as, “He is healthy because he is temperate:” but those that imply something doubtful require the subjunctive mood, as, “If I were to admonish him, he would not attend.” When the qualities of different things are compared, the latter noun or pronoun agrees with the verb, or is governed by the verb or the preposition expressed or understood; as, “You walk faster than I,” that is, “than I walk.” “They were more fortunate than we,” that is, “ than we were.” “He loved her more than me,” that is, “more than he loved me.” “It is better expressed by him than her,” that is, “ than by her.” GRAMME, the unit in French weights. It is the weight of one-hundredth part of the metre of distilled water, at its maximum density. It answers to 15.444 grains. The denomi- nations of weights proceed decimally both ways. GRANARY, a building to store corn in. - GRANATITE, a stone found in Spain, France, and Switzer- land. It is crystallized in a very peculiar form; two six-sided prisms intersect each other, either at right angles or obliquely. It is of a greyish or reddish brown colour. Specific gravity 3.2861. Usually opaque. Glassy or greasy. It is fusible before the blow-pipe. One hundred parts, consist of 44 alu- mina; 33 silica; 13 oxide of iron; 3.84 lime; 1.00 oxide of manganese. - GRAND JURY. The sheriff of every county is bound to return, to every commission of oyer and terminer, and of gaol delivery, and to every session of the peace, twenty-four good and lawful men of the county, some out of every hundred, to inquire, present, do, and execute all those things which on the part of our lord the king shall then and there be commanded them. They ought to be freeholders; but to what amount is not limited by law. Upon their appearance they are sworn upon the Grand Jury, to the amount of twelve at the least, and not more than twenty-three, that twelve may be a majority. They are only to hear evidence on behalf of the prosecution; for the finding of an indictment is only in the nature of an inquiry on accusation, which is afterwards to be tried; and . they are only to inquire, upon their oaths, whether there is sufficient cause to call upon the party to answer it. If twelve agree to find the bill, it must be pronounced a true bill, but it cannot be found by a smaller number. The mode of finding a bill is by indorsing it a true bill; when it is rejected it is in- dorsed “ignoramus,” or not found ; and no one can be tried by indictment without the finding by a Grand Jury. GRANITE is considered as the foundation rock on which slate rocks and all secondary rocks are laid. . From its great relative depth, granite is not frequently met with, except in situations where it appears to have been forced through the more superficial covering of the globe. Granite is a hard rock, whose constituent parts are the three substances, quartz, fel- spar, and mica, which are more or less perfectly crystallized, and closely united together. The three minerals of which granite is composed vary much in their proportions in different granite rocks; and often in specimens from the same rock. G R A G R A. 411. DIGTIONARY OF MECHANICAL SCIENCE. The crystals are large, or small, or equally intermixed, in one part, and in another part quartz or felspar greatly predominate. Some granites are composed of small grains, and have large crystals of felspar interspersed; these are denominated por- phyritic granites, Specimens of Cornish and Scotch granites are not difficult to procure in London, as they are commonly used for paving-stones. some specimens it is soft and earthy : the mica appears like glistening scales which have a tarnished semi-metallic lustre. The quartz has a vitreous appearance, and is of a light grey colour. In Scotch granite the felspar has more commonly a reddish brown colour. The mica is not unfrequently black and splendent: this distinguishes it at first sight from horn- blende, which is sometimes intermixed with this granite. Very small-grained granites can scarcely be distinguished from sand-stone. In general, felspar may be considered as forming the most abundant part of granite; it is sometimes in a de- composing state, owing to the potash which frequently forms a constituent part of this mineral. It is not improbable, how- ever, that what is considered as decomposing granite, may in Some instances be the original state of the rock. Granite is not stratified, but is sometimes separated into tabular masses, which have been mistaken for strata. It is more frequently divided into large masses or blocks which have a tendency to assume a rhomboidal form. Granite also exists in round masses, which are composed of concentric spherical layers, separated by granite of a less compact kind, and enclosing a harder central nucleus. These globular masses are three or four yards or more in diameter, and are sometimes found detached, and sometimes imbedded in granite of a softer kind: probably the detached globes of granite, were also once im- bedded in a similar rock, which has been decomposed and worn away. This globular structure is not peculiar to granite. When granite rises high above the surface, it forms lofty peaks and rugged piles, which at a distance resemble im- mense ruins. - GRANULATION, the method of dividing metallic sub- stances into grains or small particles, in order to facilitate their combination with other substances, and sometimes for the purpose of readily subdividing them by weight. This is done either, by pouring the melted metal into water, or by agitating it in a box until the moment of congelation, at which instant it becomes converted into a powder. . GRANT, in Law, a gift in writing of such a thing as cannot be passed or conveyed by word only, as a grant is the regular method, by the common law, of transferring the property of incorporeal hereditaments, or such things whereof no livery of seisin can be had. The operative words in grants are dedi et concessi. “I have given and granted.” Grants may be void by uncertainty, impossibility, being against law, a wrong title, or a mode to defraud creditors. - GRAPE. See WITIS. Grapes have been repeatedly examincó by the best informed chemists and most accurate tests, but without that success which might have been expected. They are found to contain much sugar, a portion of mucilage and jelly, some albumen and colouring matter. Tartrate of potash, tartaric acid ; the citric and malic acids have likewise been discovered in them. - GRAPLIN, FIRE, an instrument nearly resembling the fol. lowing, but differing in the construction of its flukes, which are furnished with strong barbs on its points; these are usually fixed by a chain on the yard-arms of a ship, to grapple any adversary whom she intends to board, and are particularly. requisite in fire-ships. - GRAPNEL, or GRAPLING, a sort of small anchor, fitted with four or five flukes or claws, and commonly used to fasten boats or other small vessels. . GRASS, in Botany, one of the seven natural families into which all vegetables are distributed by Linnaeus. They are defined to be plants which have very simple leaves, a jointed stem, a husky calyxºhamed a glume, and a single seed. This description includes corn as well as the grasses. Most of these plants are annual or perennial herbs, some of them are erect, others creep upon the ground. The roots in the greatest number creep, and emit fibres from each knot or joint; in others, they are simply branched and fibrous. The stems and In the former, the felspar is white, in branches are round; the leaves are simple, alternate, entire, very long, and commonly narrow ; they are generally placed immediately upon the stem, except in the Bamboo, and a few others which have a foot-stalk at the origin of the leaves. GRATINGS, a sort of open cover for the hatches, resem- bling lattice-work, serving to give light to the lower apart- ments, and to permit a circulation of air; both of which are . particularly necessary, when, from the turbulence of the sea, the ports between decks are obliged to be shut. GRAVE, in Music, is applied to a sound which is of a low or deep tone. The thicker the cord or string, the more grave is the note or tone; and the smaller the more acute. Grave, in the Italian music, denotes a very grave and slow motion, somewhat faster than adagio, and slower than largo. GRAVE Accent, in Grammar, shews that the voice is to be lowered ; its mark stands thus *. See Accent. GRAVEL, a congeries of pebbles, which mixed with a stiff loam, makes lasting and elegant walks. GRAVER. See ENGRAVING. - - GRAVIMETER, the name given by M. Guyton to an instru- ment for measuring specific gravities: he adopts this name rather than either areometer or hydrometer, because these latter terms are grounded upon the supposition that the liquid is always the thing weighed; whereas, with regard to solids, the liquid is but the known term of comparison to which the un- known weight is referred. This instrument is executed in glass, and is of a cylindric form, being that which requires the smallest guantity offluid, and is on that account preferable,except so far as it is necessary to deviate from the security of a ver- tical position. Like Nicholson's Hydrometer, which is else- where explained in this work, it carries two basins; one of them superior, at the extremity of a thin stem, towards the middle of which the fixed point of immersion is marked. The other, or lower basin, terminates in a point; it contains the ballast, and is attached to the cylinder by two branches. The moveable suspension by means of a hook has the inconvenience of shortening the lever which is to secure the vertical position. The cylinder is 0.71 inches in diameter, and 6.85 inches in length. It carries in the upper basin an additional constant weight of 115 grains. These dimensions might be increased so as to render it capable of receiving a much more consider- able weight; but this is unnecessary. In the lower basin used, and consequently entirely immersed in the fluid, is a bulb of glass loaded with a sufficient quantity of mercury, in order that its total weight may be equal to the constant addi- tional weight, added to the weight of the volume of water dis- placed by this piece. It will be readily understood that the weight being determined at the same temperature at which the instrument was originally adjusted, it will sink to the same mark on the stem, whether it be loaded with a constant addi. fional weight in the upper basin, or whether the effect of this weight be produced by the additional piece in the lower dish. From this explanation there will be no difficulty in seeing how this instrument may be adapted to every case in practice. It may be used, 1, for solids. It differs not in this respect from Nicholson's hydrometer. The only condition will be, as in his instrument, that the absolute weight of the body to be examined shall be rather less than the constant additional weight, which in this instrument is 115 grains. 2. For liquids of less specific gravity than water, the instru- ment, without the additional weight above mentioned, weighs about 459 grains, in the dimensions before laid down. It would be easy to limit its weight to the utmost accuracy. We have therefore the range of one-fifth of buoyancy, and consequently the means of ascertaining all the intermediate densities from water to the most highly rectified spirit of wine, which is known to bear in this respect the ratio of 8 to 10 with regard to water. - 3. When liquids of greater specific gravity than water are to be tried, the constant weight being applied below, by means. of the additional piece, which weighs about 138 grains, the instrument can receive in the upper basin more than 4 times. the usual additional weight, without losing the equilibrium of its vertical position. In this state it is capable of shewing the specific gravity of the most concentrated acids. 4. It possesses another property common to Nicholson's in- 412 G. R. A. G R A DICTIONARY OF MECHANICAL scIENCE. strument, namely, that it may be used as a balance to deter- mine the absolute weight of such bodies as do not exceed its additional load. - . . . . - - - - 5. Lastly, the purity of the water being known, it will indi- cate the degrees of rarefaction and condensation in proportion to its own bulk. . . . . . - - - This instrument may be readily constructed by any work- man in glass. The additional piece for the lower basin will require some attention to make it agree perfectly with the con- stant upper weight, as to the immersion of the instrument. . But this object may, by careful adjustment, be ascertained with the utmost certainty and accuracy. The bulb of glass is for this purpose drawn out to a fine point, a sufficient quantity of mer- cury is then introduced to sink it, and the aperture closed with a little piece of wax. The bulb being then placed in the lower basin of the instrument, the upper basin is to be loaded until the mark on the stem becomes accurately coincident with the surface of the water. The sum of the weights added above is precisely equal to that of the quantity of mercury necessary to be added to that in the glass bulb ; which done, nothing more is needed than to seal the point by fusion, taking care not to change its bulk. The whole is rendered portable by means of a case in which all the delicate parts are secured from pressure, and the heavier parts supported in such a manner as to resist the excess of motion they are capable of acquiring in conse- quence of their mass. . This last circumstance is frequently overlooked by such workmen as are employed in the package of instruments; whence it necessarily follows, that some strain or fracture must be produced when matters of very unequal density are exposed to receive a common impulse. Rule to find the specific Gravity of any Solid by the Gravimeter. “From the weight in the upper dish, when the instrument is properly immersed in the unknown fluid, take the weight which is placed with the body in the same scale at the like adjust- ment. The remainder is the absolute weight of the solid. Mul- tiply this by the specific gravity of the fluid, and reserve the product. From the additional weight when the body is placed in the lower basin, take the weight when it was placed in the upper. The remainder will be the loss of weight by immersion. Divide the reserved product by the loss by immersion, and the quotient will be the specific gravity of the solid with regard to distilled water at the standard temperature and pressure.” To find the specific Gravity of a Fluid proceed thus: “To the weight of the gravimeter add the weight required in the upper basin to sink it in the unknown fluid. Again, to the weight of the gravimeter add the -weight required in the same manner to sink it in distilled water. Divide the first sum by the latter, and the quotient will be the specific gravity of the fluid in question.” GRAVING, the act of cleaning a ship's bottom when she is laid aground during the recess of the tide. See the article BREAMING. GRAVITATION, (from gravitate, Latin), the act of tending to a centre. Or, gravitation may be more generally defined, the exercise of gravity, or the action which a body exercises on another body by the power of gravity. See Attraction. GRAVITY, (Gravitas, Latin,) in Physics, the natural tendency or inclination of bodies towards a centre. . . . Terrestrial GRAviTY, is that force by which all all bodies are continually urged towards the centre of the earth. It is in con- sequence of this force that bodies are accelerated in their fall, and when at rest that they press the body, or that part of the body by which they are supported. - As to the cause of gravity, or its nature, nothing whatever is known, and it would be useless and unprofitable to occupy any part of this article in detailing the several vague hypotheses that have been advanced to account for this most important law of nature. All that can be said is, that it appears to be an essential property of matter, or, at least, of all matter that has hitherto become the objeet of human investigation, though it is by no means certain that matter may not exist which is not subject to its influence. - This part of the subject appears to be totally out of the reach of human comprehension, instead therefore of wasting our time in useless speculation as to the cause, let us only attend to its effects, and content ourselves with examining more par- ticularly the manner in which this principle operates on mate- rial bodies, and the laws by which it appears to be regulated; the principal of which, as deduced from experiment, or from the most unequivocal inferences, are as follows: 1. That gravitation takes place between the most minute particles of bodies. 2. That it is proportional to the masses of those bodies. 3. that it varies inversely as the square of the distance in proceeding from the surface of the body upwards, or from its centre. 4. That it varies directly at the distance, in descending from the surface to the centre in uniform sphe- rical bodies, 5. That it acts equally on bodies in a state of rest, as on those in motion, and that its action in the latter case is always the same, whether that motion be to or from , the centre of attraction, or in any other direction. 6. That it is transmitted instantaneously from one body to another. With regard to this last, Laplace has shewn, that if the trans- mission of this force was not instantaneously communicated from the sun to the extreme bounds of the solar system, an acceleration would take place in the motion of the planetary bodies; and as no such acceleration has been observed, beyond what may be accounted for and computed on other principles, we have reason to conclude that the propagation of gravitation is instantaneous. . - . - - Gravity; as-relating to the science of mechanics, is divided into absolute and relative. - Absolute GRAVITY, is that by which a body descends freely and perpendicularly in a vacuum or nonresisting medium, the laws of which are given under the article AcceleRAtion. Relative GRAVITY, is that by which a body descends, when the absolute gravity is constantly counteracted by a uniform but inferior force, such as in the descent of bodies down inclined planes, or in resisting mediums. See INCLiNed Plane, Resist A Nce, and Resist ING Mediums. - Specific GRAVITY, is the relative gravity of any body or sub- stance, considered with regard to some other body which is assumed as a standard of comparison, and this standard, by universal consent and practice, is rain water, on account of its being less subject to variation in different circumstances of time, place, &c. than any other body, whether solid or fluid. And by a very fortunate coincidence, at least to English phi- losophers, it happens, that a cubic foot of rain water weighs 1000 ounces avoirdupois; and consequently assuming this as the specific gravity of rain water, and comparing all other bodies with this, the same numbers that express the specific. gravity of bodies, will at the same time denote the weight of a cubic foot of each in avoirdupois ounces, which is a great con- venience in numerical computations. From the preceding definition, we readily draw the following laws of the specific gravity of bodies ; viz. - 1. In bodies of equal magnitude the specific gravities are directly as the weights, or as their densities. 2. In bodies of the same specific gravities the weights will be as the magnitudes. - - - 3. In bodies of equal weights, the specific gravities are inversely as the magnitudes. . 4. The weights of different bodies are to each other in the compound ratio of their magnitudes and specific gravities. Hence it is obvious, that, of the magnitude, weight, and spe- cific gravity of a body, any two of these being given, the third may be found ; and we may thus find the magnitude, of bodies, which are too irregular, to admit of the application of the common rules of mensuration; or we may by knowing the specific gravity and magnitude, find the weight of bodies which are too ponderous to be submitted to the action of the balance or steel-yard; or, lastly, the magnitude, and weight being given, we may ascertain their specific gravities. Exam. The weight of a marble statue being 748 lbs. avoirdu- pois, required the number of cubic feet, &c. which it con- tains; the specific gravity of marble being 2742. Since a cubic foot weighs 2742 ounces, we have as 2742: 748 × 16 :: 1 : 4°36 feet. - 2. Required the weight of a block of granite whose length is 63 feet, and breadth and thickness each 12 feet; the specific gravity of granite being 3500. - Here 63 × 13 × 12 = 9072 feet; then again, as 1 : 9072 : : 3500 : 31752000 ounces; or 885 ton. 18% cwt. The above are said to be the dimensions of one of the stones in the walls of Balbeck. G R A G R A 413 DICTIONARY OF MECHANICAL SCIENCE. Other properties relating to the specific gravity of bodies are as follows; viz. 1. A body immersed in a fluid will sink, if its specific gravity be greater than that of the fluid; if it be less, the body will rise to the top, and be only partly immerged ; and if the specific gravity of the solid and fluid be equal, it will remain at rest in any part of the fluid in which it may be placed. 2...When a body is heavier than a fluid, it loses as much of its weight when immersed, as is equal to a quantity of the fluid of the same bulk or magnitude. 3. If the specific gra- vity of the fluid be greater than that of the body, then the quan- | tity of the fluid displaced by the part immerged, is equal to the weight of the whoſe body. And hence, as the specific gra- vity of the fluid is to that of the body, so is the whole magni- tude of the body to the part immerged. 4. The specific gravi- ties of equal solids, are as their parts immerged in the same fluid. 5. The specific gravities of fluids are as the weights lost by the same immerged solid. Hence are drawn the following rules for ascertaining the specific gravities of both solids and fluids.--To find the specific gravity of a body. This may be done generally by means of the hydrostatic balance, which is contrived for the easy and exact determination of the weights of bodies, either in air, or when immersed in water, or other fluid, from the difference of which the specific gravity of both the solid and fluid may be com- puted. 1. When the body is heavier than water. water and in water; then say, As the weight lost in water Is to the whole or absolute weight, So is the specific gravity of water * To that of the body. • : 2. When the body is lighter than Water. In this case attach to it a piece of another body heavier than water, so that the mass compounded of the two may sink together. Weigh the denser body and the compound body separately, both out of the water and in it; and find how much each loses in the water by subtracting its weight in water from its weight in air; and subtract the less of these remainders from the greater. Then use this proportion. - As the last remainder Is to the weight of the light body in air, So is the specific gravity of water To the specific gravity of the body. 3. When the specific gravity of a fluid is required. Take a piece of some body of known specific gravity; weigh it both in and out of the fluid, and find the loss of weight by taking the difference of these two ; then say, - As the whole or absolute weight Is to the weight, So is the specific gravity of the solid To the specific gravity of the fluid. In the case of solid substances, they may be either denser than water or rarer, and they may be insoluble in it or incapa- ble of solution. The mode of determining their specific gravity will accordingly be different. - 1. Insoluble solid bodies, denser than water are weighed in vacuo, and then in distilled water: and the loss of weight which they suffer by immersion, is to their whole weight, as unit is to their specific gravity, - 2. Insoluble solid bodies, lighter than water, require to be joined to some heavier substance, in order to make them sińk in that liquid. The weight of the ballast, when immersed alone, must be previously ascertained. This weight, diminish- ed, by the weight of the compound after immersion, will there- fore give the buoyant power, or the weight of a mass of water equal to the bulk of the rare substance. corrected is hence to the weight of the substance in vacuo, as unit is to its specific gravity. The computation may be simpli- fied, however, by using what is called a water-weight, or an exact counterpoise of the tongs or bucket by which the body is kept immersed in the fluid. - * 3. When the solid substances to be examined are saline, or liable to solution in water, they may be gently heated, and covered with a thin coat of melted bees’-wax. Thus defended, they may now be plunged without any risk in distilled water. Weigh it both out of A slight allowance should be made for the buoyant influence 43. The weight thus ſ: of the coat of wax itself, which, however, must be very minute, ; this plastic material has very nearly the density of water itself. . * * * . . . ; -- A solid substance, rarer than the fluid medium, must evi- dently sink, till it displace an equal weight of the fluid. The submerged part of the solid hence always marks the volume of this equiponderant mass. If the floating body have a globular shape, terminated by a long slender stem, its depression in any liquid will measure the smallest differences of specific gravity. The stem may be made exactly cylindrieah, for instance, and divided into portions which correspond to the thousandth parts. of the bulk of the ball. Such is the general construction of the hydrometer, a very convenient instrument for examining rea- dily the densities of different liquids. The stem will scarcely bear more than an hundred distinct subdivisions; but the range can be easily enlarged, by attaching, as circumstances may require, loads answering to 100, 200, 300, &c. . . . . . ; One of the easiest and simplest methods of determining the densities of different liquids, is by a set of small glass beads, previously adjusted, and numerically marked. Thrown into any liquor, the heavier balls sink, till they approach the required density, and become gradually buoyant, and the one which first rises to the surface indicates, in thousandth parts, the specific gravity of the fluid. These balls are adapted for examining liquids, whether lighter or heavier than water. But the most accurate and concise mode of ascertaining the density of liquids, is to employ a small glass measure with a very short narrow neck, and adjusted to hold exactly a thousand grains of distilled water. The vessel being filled with any other liquid, the weight of it is observed, and thence its rela- tive density to water may be found, by merely striking off three decimal places. At each operation, the glass must be care- fully rinsed with pure watcr, and again dried, by heating it, and then sucking out the humified air, for a few minutes, by help of a slender inserted tube. - ". If fluids of various densities, and not disposed to unite in any chemical affinity, be poured into a vessel, they will arrange themselves in horizontal strata, according to their respective densities, the heavier always occupying a lower place. This stratified arrangement of the several fluids will succeed, even though a mutual attraction should subsist, provided only that its operation be feeble and slow. Thus a body of quicksilver may occupy the bottom of a glass vessel, above it a layer of concentrated sulphuric acid, next this a layer of pure water, and then another layer of alcohol. The sulphuric acid would scarcely act at all upon the mercury, and a considerable time would elapse before the water sensibly penetrated the acid, or the alcohol the water. Bodies of different densities might remain suspended in those strata. Thus, while a ball of plati- num would lie at the bottom of the quicksilver, an iron ball would float on its surface; but a ball of brick would be lifted up to the acid, and a ball of beech would swim in the water, and another of cork might rest on the top of the alcohol. Table of Specific Gravities of Metals, Stones, Earths, &c. It may be convenient here to state, merely in round num- bers, the specific gravities of the more remarkable substances. * Metals. Steel, soft, . . . . . . . . . . . . 7-83 Platinum, purified, .... 19:50 — hammered, ...... 7.84 hammered, .. 20:34 || Tin, cast, . . . . . . . . . . . . 7.30 laminated, .. 20:34 Zinc, cast, . . . . . . . . . . . . 720 drawn into wire, 22:07 || Antimony, cast, . . . . . . 4.95 Gold pure and cast, .... 1926 Molybdaenum, ........ 474. — hammered, . . . . . . 19:36 |. Sulphate of barytes..... 4:43 Mercury, . . . . . . . . . . . . 13:57 Zircon of Ceylon, . . . . . . 4:41 Lead, cast, . . . . . . . . . . I 1.35 | Stones. Silver, pure and cast, ... 10:47 | Oriental ruby, ... . . . . . 4:28 — hammered, . . . . . . 1051 || Brazilian ruby, . . . . . . . . 3’53 Bismuth, cast, . . . . . . . . 9.82 Bohemian garnet, . . . . . . 4:19 Copper, cast, . . . . . . . . 879 || Oriental topaz, . . . . . . . . 4'01 . * wire, . . . . . . . . . . 8-89 | Diamond, . . . . . . . . . . . . 3'50 Brass, cast, . . . . . . . . . . 8’40 | Crude manganese, .... 3-53 wire, . . . . . . . . . . . . 8'54 | Flint glass, . . . . . . . . . . 2.89 Cobalt and Nickel, cast, 7.81 Glass of St Gobin, . . . . 2:49 Iron, cast, . . . . . . . . . . . , 7.21 | Fluor spar, . . . . . . . . . . . 3' | 8 Iron, malleable, ...... 779 Parian marble, ..... . 2-3 5 N 414 G R A G. R. E. DICTIONARY OF MECHANICAL SCIENCE. Peruvian emerald, . . . . 278 Resins, Gums, &c. Jasper, ... . . . . ........ 2.70 || Gum arabic and honey, 1'45 Earths, &c. Pitch, . . . . . . . . . . . . . . . . 1'15 Carbonate of lime, . . . . 271 Isinglass, . . . . . tº gº tº º e º G 1-11 Rock crystal, . . . . . . . . . 265 || Yellow amber, . . . . . . . . 1-08 Flint, ... . . . . . . ... . . . . . 2'59 | Hen’s egg, fresh laid, ... 1-09 Sulphate of lime, . . . . . . 2:32 || Human blood, . . . . . . . . .1*05 Sulphate of soda, . . . . . 2:20 | Camphor, . . . . . . . . . . . . '99 Common salt, ... . . . . . . . 2:13 | White wax, . . . . . . . . ... •97 Native sulphur, .. 6.... 2:03 || Tallow, ...... . . . . . . . . '94 Nitre, . . . . . . . . . . . . . . . . 2-00 || Pearl, . . . . . . . . . . . . . . . . . 2.75 Alabaster,. . . . . . . . . . . . 1-87 | Sheep's bone, . . . . . . . . 222 Phasphorus, . . . . . . . . . . 1-77 | Ivory, . . . . . . . . . . . . . . . . . 192 Plumbago, ... . . . . . . . . . 1.86 || Ox's horn, . . . . . . . . . . . . 1'84 Alum, . . . . . . . . . . . . . . . . 1.72 Wood Asphaltum, .......... 1.40 | Lignum vitae, ......... 133 Jet, . . . . . . . . . . . . we º sº dº tº gº 1'24 Ebony, ... . . . . . . ... . . . . . 1 18. Coal, from ...... l 24 to 1:30 | Mahogany, . . . . . . . . . . . 1'06 Sulphuric acid, ....... 1-84. | Dry oak, . . . . . . . . . . . . . .93 Nitric acid, . . . . . . . . . . 1-22 | Beech, . . . . . . . . . . . . . . . •85 Muriatic acid,......... 1'19 | Ash, . . . . . . . . . . . . . . . . . ‘84 Liquids, Owls, &c. Elm, from . . . . . . . . 80 to “60 Equal parts by weight of water | Fir, from ......... 57 to :50 and alcohol, . . . . . . . . ’93 i Poplar, . . . . . . . . . . . . . . . .38 Ice,. . . . . . . . . . . . . . . . . . '92 | Cork, . . . . . . . . . . . . . • . *24 Strong alcohol, . . . . . . . . '82 - Gases. t Sulphuric aether, . . . . . . ‘74 Chlorine, . . . . . . . . . . . . .00302 Naphtha, ....... ...... “Z1 Carbonic acid gas, ... '00164 Sea water, . . . . . . . . . . . . 1:03 || Oxygen gas, . . . . . . . . •09134 Oil of sassafras, ....... 1-09 || Atmospheric air, .... ‘0012l Linseed oil, ....... .... ‘94 || Azotic gas, . . . . . . . . . . •00098 Olive oil, ............. '91 | Hydrogen gas, . . . . . . .00008 White sugar, . . . . . . . . ... 1'61 - One hundred cubic inches of chlorine, carbonic acid gas, Oxygen gas, atmospheric air, azotic gas, and hydrogen gas, weigh respectively 76-2, 46.5,339, 305,29-6, and 2: 1 grainstroy. One cubic inch of distilled water at the ordinary temperature of 62 degrees Fahrenheit, weighs in air 252.5 grains. Hence the weight of a cylindrical inch of water weighs 1983 grains; but the same measure of quicksilver would weigh 2691 grains, which affords a ready method for ascertaining the diameters of very narrow or capillary glass tubes. Since the avoirdupois pound contains 7001 grains Troy, it must be equal to the weight of 27,727 cubic inches of water. Wherefore, a cubic foot of water weighs 62,322 pounds, or almost exactly one thousand ounces avoirdupois. A cubic foot. of water seems to have anciently corresponded to the weight of a bushel or firlot (fourthlet) of wheat, four of which make a boll, eight times this a ton, and the double of this again a chal- der. The ton is therefore 2000 lbs., or more generally reckoned twenty hundred weight, each hundred consisting of 112 lb. The weight of a cable of 720 feet, or 120 fathoms length, worked up from strands 180 fathoms long, is found, by multi- plying the square of the circumference in inches by 193 lb. The square of half the diameter will hence nearly express in pounds the weight of a foot of cord. A chaldron of Newcastle coals is reckoned equal to 1} ton or 3024 lb. the bushel being only the 34th part, or 84 pounds avoirdupois. When the specific gravity of any substance is known, it is easy to calculate by the foregoing table of specific gravities, the weight of any given bulk of that body, as the figures which denote the specific gravity denote also the number of ounces avoirdupois in a solid foot; the figures are now considered whole numbers. - Ea'am. 1. Of Lead. What is the weight of 7 solid feet of lead? Here the tabular number for lead is 11'352, which multiplied by 7 gives 79:464; and this divided by 16, by 28, and 4, gives 44 cwt. 1 qr. 11 lbs. 12 oz. for the quotient or weight of 7 solid feet of lead. - 2. Of Oak. What is the weight of 48 solid feet of oak From the table oak is found to contain 925 ounces in a solid foot; therefore 925 × 48- 16 by 28 and 4 gives 24 cwt. 3 qrs. 3 lbs. for the weight of 48 feet of solid oak. - - - 3. Of Cork. What is the weight of 56 solid feet of cork 2 Here from the table cork weighs 240 ounces every solid foot; therefore 240 x 56 - 16, by 28, and 4, gives 7 cwt. 2 qrs. for the answer.—This subject is treated hereafter under, the word HYDRosTAtics, and the article Solid Bodies. Floating in Fluid. GRAVITY, in Music, is the modification of any sound by which it becomes deep or low in respect of some other sound. GREAT CIRCLE SAILING, the manner of conducting a ship in, or rather pretty near the arch of a great circle, that passes through the zenith of the two places, viz. from whence she came, and to which she is bound. . - - GREEK FIRE, an invention of the middle ages, which for many years was kept a secret by the court of Constantinople, and enabled the Greeks for a time to resist the arms of the . Mahometans. It was employed in battles by land and sea, and on one occasion, was the means of destroying a fleet em- ployed in the siege of Constantinople. It continued to burn under water. The composition is now unknown, and has ceased to be an object of interest, from the invention of the more formidable fire of gunpowder. It is thought that it was made of asphalgum, nitre, and sulphur. $ - . GREEK Church. In the eighth century there arose a differ- ence between the eastern and western churches, which, in the course of about two centuries and a half, ended in a total Separation. The Greek, or Eastern, or, as it is sometimes called, the Russian church, spread itself over the eastern parts of Europe. It bears a considerable resemblance to the church of Rome, but denies the infallibility and supremacy of the Pope : it rejects also the worship of images, and the doctrine of consubstantiation, or the union of the body of Christ with the sacramental elements. The administration of bap- tism is performed, as in the case of Christ himself, St. Matth. iii., or of Philip and the Eunuch, Acts, ch. viii., by immersing the whole body. The Greek church has the same division of clergy, and distinction of ranks and offices, with the church of Rome. GREEN, one of the original colours excited by the rays of º and which colour depends on the absorption of carbonic a Cl Cl, - - GREEN, Brunswick, is made by saturating cold water with nuriated ammonia, and adding three times as much copper clipping as ammonia. The moisture is to be evaporated, taking care that no dust be allowed to get to it. The muriate of ammonia is decomposed by the copper, which is itself cor- roded and converted into a green oxide. It is then to be digested in successive portions of alcohol, as long as any green oxide is taken up; the solutions are now to be added together, and the liquor to be driven off by a moderate heat; the resi- due is the pigment required. - GREEN Cloth, a board or court of justice, held in the counting house of the king’s household, composed of the lord steward and officers under him, who sit daily. To this court is commit- ted the charge and oversight of the king's household in matters of justice and government, with a power to correct all offend- ers, and to maintain the peace of the verge, or jurisdiction of the court royal ; which is every way about two hundred yards from the last gate of the palace where his majesty resides. Without a warrant first obtained from this court, mone of the king's servants can be arrested for debt. GREENHOUSE, or conservatory, a house in a garden con- trived for sheltering and preserving the most tender and curious exotic plants, which, in our climate, will not bear to be exposed to the open air during the winter season. These are generally large and beautiful structures, equally ornamental and useful. - - GREGORIAN CALENDAR, that which shews the new and full moon, with the time of Easter, and the moveable feasts depending thereon, by means of epacts, disposed through the several months of the Gregorian year. - GREGoRIAN Epoch, the epocha or time whence the Grego- rian calendar or computation took place. The year 1826 is the 244th year of that epocha. -- - GREGokIAN Year, the Julian year corrected or modelled in such a manner as that three secular years, which in the Julian account are bissextile, are here common years, and only every fourth secular year is made a bissextile year. The Julian computation is more than the solar year by eleven minutes, which in one hundred and thirty-one years amounts to a whole day. By this calculation the yernal equinox was G R I G R O 415 DIC"I'IONARY OF MECHANICAL SCIENCE. anticipated ten days from the time of the general council of Nice, held in the year 325 of the Christian era, to the time of Pope Gregory XIII., who therefore caused ten days to be taken out of October, in 1582, to make the equinox fall on the twenty-first of March, as it did at the time of that council; and to prevent the like variation for the future, he ordered that three days should be abated in every four hundred years, by reducing the leap-year at the close of each century for three successive centuries to common years, and retaining the leap- year at the close of each fourth century only. This is not exactly conformable to the true solar year, because that in four hundred years it gets one hour and twenty minutes. - - GRENADE. or GRENADo, is a kind of small bomb or shell, being furnished with a touch-hole and fuse, and is thrown by hand from the tops, &c. whence they are most generally styled hand-grenades. See the article ENGAGEMENT. Thuanus ob- serves, that the first time grenadoes were used was at the siege of Wacklindonck, a town near Gueldres; and that the inventor was an inhabitant of Venice, who, in making an experiment of the effect thereof, occasioned two-thirds of that city to be burnt, the fire having been kindled by the fall of a grenado. The best way to secure a man's body from the effect of a grenado is to lie flat down on the ground previous to its explosion. - - - GRENAILLE, a preparation of copper, which the Chinese use as a red colour in some of their finest china. This colour is thus obtained: when copper is in fusion, water is sprinkled over it, and a pellicle or coat forms itself on the surface of the copper, which is taken off with iron pincers, and immediately thrown into a vessel of cold water, where it forms, by precipi- tation, the red colour named Grenaille. GREY WACKE, a coarse kind of slate, which has been so named by the Germans. It is thus described by Dr. Thompson: “Greywacke is composed of grains of sand, which are of various sizes, and sometimes even approach in magnitude to rolled masses. These are connected together by a basis of clay-slate, (common slate,) and hence this rock derives its grey colour and solidity. These fragments are sometimes quartz, some- times a kind of indurated clay-slate, and sometimes flinty-slate, The texture of greywacke becomes gradually finer and finer grained, till at last it can no longer be perceived, and a slaty structure succeeds. It then passes into greywacke slate. Greywacke slate is nothing else than a variety of clay-slate. GRIFFON, in Heraldry, an imaginary animal feigned by the ancients to be half eagle and half lion ; by this form they intend- ed to give an idea of strength and swiftness joined together, with an extraordinary vigilance in guarding the things intrust- ed to its care. e GRINDING, the reducing hard substances to fine powders, either by the mortar, or by way of levigation upon a marble. GRIPE, a piece of timber faced against the lower piece of the stern from the foremost end of the keel, joining with the knee of the head: its use is to defend the lower part of the stern from injury, but is often made the larger, that the ship may keep a good wind. See the article ForeFoot. GRIPE of a Ship, is the compass or sharpness of her stern under water, chiefly towards the bottom of her stern. The design of shaping her so is to make her gripe the more, or keep a good wind, for which purpose, sometimes a false stern is put upon the true one. . . GRIPES, a machine formed by an assemblage of ropes, hooks, and dead-eyes, and used to secure the boats upon the deck of a ship at sea, and prevent them from being shaken by the labouring of the vessel. The hooks, which are fastened at their ends, are fixed in ring bolts in the deck on each side of the boat; whence, passing over her middle and extremities, they are extended by means of the dead-eyes, so as to render the boats firm and secure. - GRIPING, the inclination of a ship to run to windward of her course, particularly when she sails with the wind on her beam or quarter: this effect is partly occasioned by the shock of the waves that strike the ship perpetually on the weather quarter, and force the stern to leeward; but principally by the arrangement of the sails, which disposes the ship continually to edge to windward, while in this situation of sailing; in such case they say, she gripes or is griping. GRIT, a genus of argillaceous earths, with a texture more or less porous, equable and rough to the touch. It neither gives fire with steel nor effervesces with acids. When fresh and breathed on, it exhales an earthy smell. Its specific gravity varies from 2.0 to 2.6, and is used for mill-stones and whet-stones, and sometimes for filtering-stones and building. g GROG, a general name for any spirituous liquor and water mixed together; but is more particularly applied to rum and water cold without sugar. - - GROIN, among Builders, is the angular curve made by the intersection of two semi-cylinders or arches; and is either regular or irregular:—regular, as when the intersecting arches, whether semicircular or semi-elliptical, are of the same diame- ters and heights, and irregular, when one of the arches is semicircular, and the other semi-elliptical. GROMMET, a sort of ring or small wreath formed of a Strand of rope laid in three times round; used to fasten the upper edge of a sail to its stay in different places, by means of which the sail is accordingly hoisted or lowered. Instead of grommets, hanks have been lately introduced. See the article. HANKS. - GROSS, in law books, signifies absolute or independent on another: thus an advowson in gross is one distinct and sepa- rate from the manor. ** - G Ross Beak, the English name of a bird called by authors ſoxia. See Lox IA. - GRoss Weight, the whole weight of merchandises, with their dust and dross; as also the bag or chest wherein they are con- tained. An allowance is usually made out of the gross weight for tare and tret. See TARE. GROTTO, a large deep cavern or den in a mountain or rock. G Rotto del Cane, is a little cavern near Pozzuoli, two miles from Naples ; the air contained in it is of a mephitical or nox- ious quality, it is in truth carbonic acid gas. The vapour rises only to a certain height. When a dog or any other creature is forcibly kept below it, or cannot hold its head above it, it presently loses all motion, and falls down in a swoon, the limbs convulsed and trembling, till at last no more signs of life appear than a very weak and almost insensible beating of the heart and arteries, which, if the animal is left a little longer, quickly ceases too, and then the case is irrevocable; but if it is snatched out and laid in the open air, it soon comes to life again, and sooner, if thrown into the adjacent lake. The effects are produced merely by carbonic acid gas, which accumulates at the bottom of the grotto. A human being is perfectly safe, because the gas rises only a short way from the bottom ; but if a man were to lie down, he would suffer in the same manner as a dog. - - GRotto, is also used for a small artificial edifice made in a garden, in imitation of a natural grotto. The outsides of these grottos are usually adorned with rustic architecture, and their inside with shell-work, coral, &c. The following is a good cement for grotto-work: Take two parts of white resin, melt it clear, add to it four parts of bees-wax; when melted together, add some flour of the stone you design to cement, two or three parts, or so much as will give the cement the colour of the stone; to this add one part of the flower of sulphur; first incorporate all together over a gentle fire, and afterwards knead it with your hands in warm water. With this fasten the stones, shells, &c. after they are well dried, and warmed before the fire. • , GROUND, in Painting, the surface upon which the figures and other objects are represented. See PAINTING. GROUNDING, the act of laying a ship on shore, in order to bream or repair her; it is also applied to running aground accidentally when under sail. -- . . . GROUND TAckle, a general name given to all sorts of ropes and furniture which belong to the anchors, or which are employed in securing a ship in a road or harbour; as cables, anchors, bow-lines, &c. GROUP, in Painting and Sculpture, is an assemblage of two or more figures of men, beasts, fruits, or the like, which have some apparent relation to each other. GRoup, in Music, one of the diminutions of long motes, which in working form a sort of group, knot, or bush. GROUSE, a species of the Tetrao. 416 G. U A. G U A. DICTIONARY OF MECHANICAL SCIENCE. GROWING, implies the direction of the cable from the ship towards the anchors, as, the cable grows on the starboard-bow, i.e. stretches out forwards towards the board or right side. . . GRUB, the name of worms produced from the eggs of bee- tles, which are at length transformed into winged insects of the same species with their parents. - - GRUS, the CRANE, contains thirteen stars, viz. one of the 2d magnitude, two of the 3d, and two of the 4th; and the whole constellation culminates with Cygnus and Aquarius, but no part of it is visible in our latitudes. 3, the brilliant in the eastern wing of the Crane, and of the 2d magnitude, has xxi ho. 56mi. 58 sec. right ascension. in Time; (Ann. War. 3".84,) and 47° 48' 50" declination south, (Ann. War. — 17”. 15.) This star culminates for the 1st of each month in the year, agreeably to the following table, rectified for 1822 in astrono- mical time. - CULM. MONTH. CULM. MoNTH. MonTH. CULM. - ho. mi. sec. ho. mi. sec. ho. mi. sec. Jan. 3 10 16 May 19 21 34 Sept. 11 15 0 Feb. | 0 58 20 June | 17 19 4 || Oct. 9 27 12 Mar. 23 5 45 July 15 15 9 Nov. 7 31 14 April | 21 12 35 Aug. 13 10 44 Dec. 5 27 46 GRYLLOTALPA, the Mole Cricket, a species of gryllus with the anterior feet palmated. - - GRYLLUS, in Natural History,the Locust, Grasshopper, and Cricket, a genus of insects belonging to the order hemiptera, of which there are 61 species. Among the most numerous species is the gryllus migratorius of Linnaeus, or common migratory Hocust. Legions of these animals are from time to time ob- served in various parts of the world, where the havock they commit is almost incredible : whole provinces are in a manner desolated by them in the space of a few days, and the air is darkened by their numbers; nay, even when dead, they are still terrible ; since the putrefaction arising from their incon- ceivable number is such that it has been regarded as one of the probable causes of pestilence in the eastern regions. One of the largest species of locust yet known is the gryllus cristatus of Linnaeus, five or six times the size of the gryllus migrato- rius; and together with some others of the large kind, is made use of in various parts of the world as an article of food. The gryllus viridissimus of Linnaeus, one of the largest European species, is often seen during the decline of summer in our own country. GUANO, a substance found on many of the small islands in the South Sea, which are the resort of numerous flocks of birds, particularly of the ardea and phaenicopterus genus. It is dug from beds fifty or sixty feet thick, and used as a valuable ma– nure in Peru, chiefly for Indian corn. - GUARD, in a general sense, signifies the defence or preser- vation of any thing; the act of observing what passes, in order to prevent surprise; or the care, precaution, and attention, we make use of, to prevent any thing happening contrary to our intention or inclinations. : GUARD, in the Military art, is a duty performed by a body of men, to secure an army or place from being surprised by an enemy. In a garrison the guards are relieved every day, and it comes to every soldier's turn once in three days. - GUARD, Advanced, is a party of either horse or foot, that marches before a more considerable body, to give notice of any approaching danger. GUARD, Artillery, is a detachment from the army to secure the artillery. • * - GUARD, Main, that from whence all the other guards are detached. - - ... . . .--" " GARD, Piquet, a good number of horse and foot, always in readiness in case of an al-Tim; the horses are all the time sad- dled, and the riders booted. - ... Gººd Boat, a boat appointed to row the rounds among the ships of war in any harbour, to observe that their officers keep a good look-out. - - - GUARD Ship, a vessel to superintend the marine affairs in a harbour or river, and to see that the ships which are not com- missioned have their proper watch duly kept. GUARD, in Fencing, is a posture proper to defend the body. from an enemy's sword. There are several guards of the sword, but they may all be réduced to four; to form a perfect idea of which, we must suppose a circle drawn on a wall, and divided into four cardinal-parts, viz. top and bottom, right and left. When the point of the sword is directed to the bottom of the circle, with the hilt opposite to its top, the body inclining very forward, this is called the prime, or first guard. The second guard is when the point is directed to the right or se. cond point of the same circle, with the hilt of the sword turned to the left, and the body proportionably raised. The tierce, or third guard, is when the point of the sword is raised to the uppermost part of the same circle, in which case the body, the arm, and the sword are in their natural position, and in the mean of the extremes of their motion. The quart, or fourth guard, is when the point of the sword is directed to the fourth point of the circle, descending to the right as far as one-fourth of the tierce, with the outward part of the arm and the flat of the sword turned towards the ground, and the body out of the line to the right, and the hilt of the sword towards the line to the left. There is also a quint, or fifth guard, which is only the return of the point of the sword to the right, after traversing the circle to the point of the prime, from whence it had depart- ed, with a different disposition of the body, arm, and sword. The common centre of all these motions ought to be in the shoulder. - - - - GUARD-Irons, curved bars of irons placed over the orna- mental figures of a ship's head or quarter, to defend them from Injury. GUARDIAN, in Law, is one appointed to take care of a per- son and his affairs, who by legal imbecility and want of under- standing, is incapable of acting for his own interest. Guardian by nature, is the father or mother; and by the common law every father has a right of guardianship of the body of his son and heir until he attains to the age of 21 years. This guardianship extends no farther than the custody of the infant’s person. The father may disappoint the mother, and other ancestors, of the guardianship by nature, by appointing a tes- tamentary guardian. - GUARDIAN, by the Common Law, or Guardian in Soccage, may be thus explained. If a tenant in soccage die, his heir being under 14, the next of blood to the heir, to whom the inheritance cannot descend, shall be guardian of his body and land till 14 ; the heir after 14 may choose his own guardian, who shall continue till he is 21. The guardians in soccage are to transact all affairs in their own name, and not in the name of the infant. - GUARDIAN by Statute, or Testamentary Guardian. By the statute 12 C.II. c. 24. a father may, by deed or will, attested by two wit- nesses, appoint, dispose of the custody of his child, born or un- born, to any person except a popish recusant convict, either in possession or reversion, till such child attain 21. This guardian supersedes the guardian in soccage, and has all actions which that guardian might have had. Besides which he has the care of the estate, real and personal. A father cannot, under this statute, appoint one to his natural child. The chancellor, however, will upon application appoint the same person guardian. - GUARDIANs by custom are appointed in the city of London, in the county of Kent, and, with respect to copyhold lands, in SOme manOrS. - GUARDIAN, in Chivalry, is obsolete, but extended to twenty- one years. * - - - GUARDIAN, by appointment of the lord chancellor. The court of chancery is the only proper court that has jurisdiction in appointing and removing guardians, and in preventing them and others from abusing the persons or estates. The court determines, as to the right of guardianship, who is the next | of kin, and who the most proper guardian ; as also orders are made on petition or motion for the provision of infants during any dispute therein; as likewise guardians removed or com- pelled to give security; they and others punished for abuses committed on infants, and effectual care taken to prevent any abuses intended them in their persons or estates. All courts of justice appoint guardians to infants, to see and prosecute their rights in their respective courts when the occasion calls for it. There are also some cases where an infant may elect a guardian, and the court of chancery allows him to do so after 14. - G U D G U M DICTIONARY OF MECHANICAL SCIENCE. 417 GUARDIAN of the Spiritualties, is he to whom the spiritual jurisdiction of any diocese is committed during the vacancy of the see. - . - GUDGEONS, in Machinery, having all the weight on the shaft to support, ought to be made sufficiently strong for that -purpose; while, to avoid unnecessary friction, they should be made as small in diameter as possible, consistently with the requisite strength and durability. Wrought iron being stronger than cast iron in about the ratio of 7 to 5, will bear a greater weight; yet, cast iron being cheaper, and more easily shaped, is more frequently employed for gudgeons. - f Rules for the Gudgeons of Water-wheels.—1. The cube root of the weight of a water-wheel in hundred weights, is nearly equal to the diameter in inches, of a cast-iron gudgeon sufficiently strong to support such wheel. 2. For wooden water-wheels, multiply the diameter in feet by the width also in feet, to which add the square of half the diameter: the cube root of the sum will be nearly equal to the diameter of the gudgeon in inches. These, of course, must be regarded as approximations: but it has been inferred from several experiments, that gudgeons of the same size, of cast and of wrought iron, are capable, at a medium, of sustaining weights without flexure, in the propor- tion of 9 to 14. Upon this principle has been computed the following table, to shew the proportionate diameters of cast- iron and wrought-iron gudgeons. - TABLE of Cast and Wrought Iron Gudyeons. fe 2 3 4 Diameter Cube of diameter of cast-cube of diameter . Diameter |of cast-iron iron gudgeons, or the of wrought iron of wrought iron | gudgeons owls, which the gudg-| .d. gudgeons in in inches. eons may sustain. , gll (ig vs. inches and parts. 1. 1. *6428571 •863054 | 1:25 1.953.125 1.2555803 | 1.063340 1'5 3.375 2. 1696427 1.25992.1 1.75 5' 35.9375 3'4453.125 1'514825 2. 8. 5'142857 l. 1709976 2.25 11°400625 7.3289732 1°912933 . 2 5 15'625 10°()446428 2' 154435 2.75 20.796875 13°36941.96 2°35.1335 3. 27. 17,3571428 2'571282 3 25 34'328.125 22:0670803 2'802039 3°5 42'875 27°5625 3°018294 3.75 52*734375 33.9006696 3°23961.2 4” 64" 4.1. 14285,71 3'448217 4°2 76'7656.25 49.3493303 3:659306 4'5 91.125 58'58035.71 || 3-881936 47 107° 17 i 875 68°896 4' 101566 5° 125° 80°357 4°308870 5' 25 144*763125 93-023 4:530655 5'5 166°375 106.955 4:747459 5°75 190° 109375 122-213 4'959675 6. 216? 138-857 5' 1801.01 6.25 244° 140625 156'948 5°394690 6'5 274°625 176'545 5'609376 6.75 307'546875 197709 5'828476 7. 343° 220-500 6:041377 7.25 381'078'ſ 25 244'979 6.257324 7.5 421 '875 271-205 6°471274 7.75 465'484375 299-240 6-686882 8" 512- 329-143 6'903436 8'25 561'515625 360°975 7. 120367 8'5 614° 125 394.795 7.337234 8.75 669'92.1875 430°664 7.553688 9. 729. 468°643 7 769.462 9.25 791'45.3125 508-791 7°984344 9'5 875' 375 562-74.1 8'257.263 9.75 926'859375 595'837 8’415541 10. 1000' 642-857 8°63.1103 10°25 1076'890625 692.287 8°845085 10:5 l 157.625 744, 187 9-061309 10'75 1242'296875 798.619 9°279.308 I 1. 1331° 855'643 9°49.3599 44. Erplanation of the Table of Cast-iron and Wrought-iron Gud. geons.—Column 1, and 2 are the same as those calculated for cast-iron gudgeons. Column 3 contains numbers in the pro- portion of 9 to 14 less than those in column 2. Column 4 con- tains the cube root of column 3, or the diameters of wrought- iron gudgeons, having the same strength as those of cast-iron in column 1. - - - Use of the Table.—Example. To find the diameter of a wrought-iron gudgeon of the same strength with one of cast- iron of 3 inches diameter: Look on the 1st column for 3, and on the same line in the 4th column will be found 2-571282, that is, a little more than 2% inches, the diameter required of the wrought-iron gudgeon. The numbers in the 3d column, being the cube of those in the 4th, another use may be made of this part of the table. For, supposing the 4th column to represent cast-iron gudgeons, the 3d column will represent the hundred weights which cast-iron gudgeons of those diameters should Sustain. - GUIACUM, or GUAIA CUM, is a gum resin, extracted from a West Indian tree called the guaiacum officinale. A part is solu- ble in water, the rest in alcohol. It is used in syphilis, and other complaints; chiefly in rheumatism, dissolved in ammonia. GUILD, or Gild, a fraternity or company. Among the Saxons the law enacted, that every freeman of 14 years of age should find securities to keep the peace, or be committed : upon which the neighbours entered into an association, and became bound for each other, either to produce him who com- mitted any offence, or to make satisfaction to the injured party, in order to which they raised a sum among themselves, which they put into a common stock. These guilds are now compa- nies, with laws and orders made by themselves, by the license of the prince. - - - - - GUINEA, a gold coin struck in England. The pound weight troy of gold is cut into 44 parts and a half, and each part makes a guinea, which is therefore equal to # lb. or § oz. or 5 dwts. 9; gr. - GUITAR, or GUITARRA, a musical instrument with five double rows of strings, of which those that are bass are in the middle. GUM, a thick transparent tasteless fluid, that exudes from certain species of trees. It is adhesive, and gradually hardens without losing its transparency. Gum is chiefly obtained from different species of the mimosa, particularly M. Nilotica, a native of Egypt and Arabia, which is known by the name of gum arabic. The specific gravity of gum is about 1.4. It is not changed by exposure to the air, but is deprived of its colour by the action of the sun. By heat it becomes soft, and is spee- dily reduced to the state of charcoal, which enters largely into its composition. The constituent parts of gum are carbon, hy- drogen, and oxygen, with smaller proportions of nitrogen and lime. The oxygen is much less in quantity than the sac- charine matter. - Gum readily dissolves in water, and the solution, which is thick and adhesive, is known by the name of mucilage. It is soluble also in the vegetable acids. Sulphuric acid decomposes it, and converts it into water, acetic acid, and charcoal. With the assistance of heat, muriatic acid and nitric acid produce a similar effect. It is insoluble in alcohol and ether, Such are the chief properties of gum arabic.—There are, besides this, other gums, of which the principal is denominated tragacanth, from the astragalus tragacantha, a native of the island of Crete, which is in the form of vermicular masses; it is less transpa- rent and more adhesive than gum arabic. In our gardens and orchards, we find gum exuding from the cherry and plum | trees, which differs chiefly from gum arabic in being softer and more soluble. Gum in a state of mucilage exists in the roots and leaves of a number of plants. It is most abundant in bul- bous roots, and of these the hyacinth seems to contain the | largest quantity. A pound of the bulbs of this root, when | dried, yields four ounces of a powder, which, when macerated | in water, gives a mucilage that acts well as a mordant for fixing the colours in calico printing. Gum is used in medicine, and is considered as a specific against the strangury occasion- ed by blisters; it constitutes, under particular forms, a nutri- tious food, and it is an important article in the , manufacture of ink. 5 O 418 G U N G U N DICTIONARY OF MECHANICAL SCIENCE, GUM Resins, are certain substances that haye been used in medicine. They are all solid, generally brittle and opaque, have a strong smell, and a pungent and bitter taste. They consist chiefly of gum and resin, the proportions varying with the particular substance. They are procured by wounding the plants which contain them. The principal of the gum resins are, 1. Ammoniac. 2. Asafoetida. 3. Euphorbium. 4. Gal- banum. 5. Gamboge. 6. Myrrh. 7. Oppoponax. 8, Sapa- genum, supposed to be had from the ferula persica. All the gum resins which have been analyzed have been found to contain ammonia. - - GUN, called by the general name of Cannon, (see that arti- cle,) and distinguished by the epithet “great gun' from the small guns, firelocks, muskets, blunderbusses, &c. See the Plate of GUNS. . A truly fortified great iron gun ought to measure eleven dia- meters of the bore at the circumference of the base ring, nine diameters at the trunnions, and seven at the circumference of the muzzle ring. . . . . - - A truly fortified great brass gun should measure two diame- ters less at each place of measurement than the iron gun ; that is to say, nine diameters of the bore at the circumference of the base ring; seven at the trunnions, and five at the muzzle Tingſ. - #. order to discover when a gun quadrates or hangs well in the carriage, it ought to measure in length seven times her own diameter at the vent; the trunnions ought to be placed at the distance of three diameters from the base ring; then there will remain four diameters in distance from the muzzle. In order to discover whether the carriage is proper, and of due length for the gun, it ought to be five-eighths the length of the gun, and then the eye will easily discover if it be wide enough, and high enough, or too high. . To dispart a gun, in order to take proper aim at the given object, insert a priming wire into the vent, and let it touch the lower part of the metal of the bore ; mark the wire close to the vent, take it out, and rest it on the lower metal of the rose at the muzzlé, and the distance between the muzzle-ring and marked part of the wire is the height of the dispart. In order to find the thickness of the metal at the vent, trun- nions, and muzzle, take the diameter of the gun at the vent, and lay it down thus | –— |, which will express the diameter; then insert a priming wire into the vent, and let it rest on the lower metal ; mark it close to the vent, and, taking it out, lay the mark on the line of the diameter, thus : * tº Crook then the end of the wire a little, that it may enter the vent, and, inserting it a second time, turn it round till it catch- es the upper metal of the bore; then mark it again close to the vent, set off the distance on the same line of the diameter, and mark how far it reaches from the end of the line, thus; A B A. | -—— | | — Then will A and A represent the thickness of the metal, and B the bore of the gun; and if the portions A, A of the line are equal to each other, the thickness of the metal is equal, and, of course, the gun centrally bored. Girt then the gun at the trun- nions with waxed twine, and if it measures nine diameters of the bore, the gun is so far truly fortified. Observing the same operation at the muzzle, where it is to measure seven diame- ters, the process is complete. In order to discover whether a gun is truly bored, take a spare sponge-staff, and fix on it a rammer-head, strike a chalk. line on it, from one end to the other, and put it into the gun as far as it will go, keeping the chalk line uppermost, and exactly in the centre; then prick down the vent with a priming wire, and if you find, on taking out the rammer, you have pricked into the chalk-line, you may reasonably conclude the gun is truly bored ; but if you miss the chalk line, that it is not. In order to discover when a gun is honey-combed, take a spring searcher with five prongs and a reliever: muzzle the searcher, and ram it home in the gun; take off the reliever, and keep turning the searcher backwards and forwards; you will easily discover whether it catches; when it does, mark the staff close to the muzzle; then turn the searcher again as be- fore, and whenever it catches again, mark the staff as in the *sº gº &== sºmeº former instance; so that by laying the staff when drawn out on the outside of the gun, you may nearly judge, where the honey-combs are. . . . . ; In order to discover the depth of the honey-combs, take a searcher with one prong and a reliever: arm the end of the prong with wax, then ram it home in the gun : take off the re- liever, and turn the searcher till it catches; then will the im- pression made in the wax shew the shape and , depth of the honey-comb. º - . . . . . . If the honey-comb on either side or on the lower metal between the breech and the reinforce ring is three-tenths of an inch deep, the gun is to be condemned; if on the upper metal, four-tenths; if on any part without or beyond the reinforce ring, five-tenths are sufficient. - . . ; N. B. A most ingenious instrument, invented by the late General Desaguliers, and since brought to the greatest perfec- tion, has totally superseded the use of this contrivance. All guns intended for sea service are now previously examined by proper officers belonging to the ordnance board, who, by means of this instrument, being able to ascertain with the greatest precision the state and defects of any gun, after a very short examination, of course reject all those which, either from natu- ral defect or subsequent injury, appear unfit for his majesty's Serv ICS. - . To discover whether a gun is sound or cracked, strike a smart blow on it with a hammer: if it rings clear, it may be con- cluded the gun is sound ; if it jars, or emits a hoarse sound, it is most probable the gun is cracked. Or the following method may be taken : stop the vent; and take a piece of touchwood; put it into the gun, and stop the muzzle securely ; let the touchwood remain in the gun four or five minutes: if the gun is cracked, the touchwood will burn out; if the gun is sound, it will be extinguished. - - - In fitting a shot to a gun, divide the diameter of the bore into twenty equal parts, and the diameter of the shot ought to be nineteen of those parts. . With respect to the proper proportion of powder, eighteen- pounders and all inferior calibers require half the weight of the shot; for all above, there are certain rules to find the proper proportion by. • . In order to secure a gun, if it break loose, cut down the ham- mocks, trip the gun, and lash it to the ring-bolts of the side till fine weather. To clear it when a bit is broken in it, draw the gun, and sprinkle powder with a ladle from the breech to the . muzzle ; this done, drive in a tight tompion with a small score in it, and blow the gun off. * - If a shot has fetched way in the gun, in order to secure it, damp the powder or split the tompion : then insert a rope sponge of a small size, and drive the wad home. If in loading the gun the shot sticks by the way, and if, in firing it, it splits, and you cannot draw the gun; in order to | free it, the powder must be damped, and while that is soaking some powder must be mealed, and the gun primed, getting as much powder down the touch-hole as possible; then the gun must be fired off. - When a ship is going to sea immediately, the articles which should be ready for action are, the powder filled, the powder- horns and partridge or grape shot between the guns, hammered shot in the buckets, crows and hand-crows, levers at the guns; nets and cheeses of wads fore and aft; the match-tubs in their proper places, the matches ready, the lockers full of shot, the spare tackles and breechings ready, wet swabs at the door of the magazine and heads of the ladders; the boxes of hand-gre- nades ready for the tops. The thickness of the metal of a gun at the vent should be one diameter and a quarter of the bore: in an engagement, there should be one man to every five hundred weight of metal. ' The pointing of a gun, so as to strike distant objects, de- | pends on two things, viz. 1. Tracing on the outside of the piece a visual line parallel to the axis, which is called disparting, and is performed by taking half the difference of the diameters of the muzzle and base-ring and setting it perpendicularly on the muzzle-ring directly over the centre: for then a line which passes from that point in the base-ring, will, when the piece is truly bored, be parallel to its axis. 2. The other operation is the determining the allowance to be made in distant shot for G UN G U N DFCTIONARY OF MECHANICAL". SCI F.N.C.E. 419 the incurvation of the flight of the bullet; this is greater or less (caeteris paribus) according to the different charges of powder made use of. - N. B. The foregoing principles, remarks, &c. are applicable chiefly to marine artillery, or sea batteries; the details to be found under the words CANNON, CANNoNADE, &c. will be read to advantage, in conjunction with the foregoing and succeed- ing articles. s - . The Morning GUN, a gun fired by an admiral or commodore at day-break every morning. - . . . . . . - . The Evening GUN, one fired by the above at nine o'clock in summer and eight o'clock in winter, every night. - GUN Boat, a boat fitted to carry one or more cannon in the bow, so as to cannonade an enemy while she is advancing towards him : they are principally useful in fine weather, smooth water, and shallow ground, to cover the landing of troops, or on such occasions. - - - GUNNER of a Ship of War, an officer appointed to take charge of the ammunition and artillery aboard, to keep the latter pro- perly fitted and in order, and to teach the sailors the exercise | of the cannon. - - - GUNNER's Mate, a petty officer appointed to assist the gun- YMCT, - - • - - - Percussion GUN. See PERcussion. It has been proposed to ignite great guns and hand-grenades by means of percussion caps, and there can be no doubt of the practicability of this design; but as we have not yet received any certified accounts of actual experiment on this application of the principle of percussion, we shall do no more than touch upon the subject, till we come to the word Percussion. - Quarter GUNNERs, men placed under the direction of the gun- ner to perform any work relating to the cannon, &c. which he may command ; their number is always proportioned to the number of the ship's artillery, one quarter-gunner being allow- ed to every four guns. - - - w GUN Room, an apartment on the after end of the lower gun- deck, of large ships of war, partly occupied by the gunner, but in frigates and smaller vessels, where it is below, it is used by the lieutenants as a mess room. • GUN Shot, implies the distance of the point-blank range of a cannon-shot, a ship is therefore said to be within gun-shot when shē is within that distance. - GUN Tackles, are pulleys affixed to each side of the carriage; their use is to run the gun out of the port, or to secure it when at Sea. - GUNNERY, the art of charging, directing, and exploding all kinds of fire-arms, though the term is more commonly restricted to the larger pieces of ordnance, as cannons, mor- tars, &c. - .. t - To this art belongs the knowledge of the force and effect of gunpowder, the dimension of the pieces, and the proportions of the powder and ball they carry, with the methods of adjusting, pointing, spunging, &c. Gunnery may be therefore divided into theoretical and practical, which equally belong to a work of this description. Theoretical gunnery consists in com- puting the angles of elevation, the impetus of projection, the range of the ball, &c. from certain data previously established; we may also consider those experiments which have been made with a view to ascertain the velocity of projection with given charges, the resistance of the air, the deflection of the ball or of the gun, &c. as forming a part of theoretical gunnery. But the best introduction we can offer to the practical rules of gunnery, will be a general view of the Parabolic Theory of the motion of projectiles in vacuo ; that is, of the mathematical principles by which the several circumstances relative to their motion might be determined, if their progress was not impeded or disturbed by the air. Parabolic Theory of Gunnery.—The motion of a falling body is uniformly accelerated, and that of a body thrown straight upward is uniformly retarded. A falling body acquires an increase of 32, feet per second in every second of its fall, and an ascending body has its velocity lessened as much during every second of its rise. - - The space described during any portion of time by a motion uniformly accelerated from rest, is one half of the space uni- formly described in the same time with the final velocity of the accelerated motion; and the spaces described from the begin- ning of the motion are as the squares of the times. . . . . . . When a body is projected in any direction not perpendicular to the horizon, it will describe a parabola, of which the axis is perpendicular to the horizon. . . * - . a Let the body be projected from the point A (fig. 1,) in the direction AL, with the velocity which a heavy body would •. Fig. 1. . . acquire by falling freely through . . . . the space CA; the body, by the continual action of gravity, will be continually deflected from the line A L, and will describe the parabolic curve A V B, of which the vertical line C A F is Fºr a diameter, A the vertex of this / diameter, and A L a tangent at A. . . - - Through V, B, any two points of the curve, draw V K, BL, parallel to C A, meeting AL in K and L; and draw V F, BG, parallel to A L, meeting CA produced in F and G. Then let KV, L B, be the spaces through which the body would descend by its gravity in the same times in which it would uniformly pass over the corre- sponding spaces A. K, A L, by the projectile motion; it is plain, from the composition of mo- tions, that the body would ar- rive at the points V, B, of the curve in the same time that it w would have uniformly described G A K, AL, with the velocity of the projection, or that it would have fallen through AF, A G. But because the motion along A L is uniform, A K is to A L, as the time of describing A K to the time of describing A L. And because the motion through A G is uniformly accelerated, A F is to A G as the square of the time of de- scribing AF to the square of the time of describing A G ; that is, as A K2 to A L’, or as V F* to B G*. Consequently the curve is such that the abscisses A F, A G, are as the squares of the corresponding ordinates V F, B.G.; that is, the curve is a parabola, and A L, parallel to the ordinates, is a tan- gent at the point A. > . - . . . - If a body be projected from any point A (fig. 1,) in any direc- tion A L, with the velocity acquired by falling from C ; the horizontal line C E, drawn through the point C, is the directriæ of the parabola described by the body, Take A F = CA, then the time of falling through A F is equal to the time of falling through C A ; but A K is described with the velocity acquired by falling through CA, and there- fore A K = 2C A, and V F = 2 AF; consequently V F2 = 4 AF2 = 4 A F x A F = 4 C A × A F ; but in a parabola, the square of any ordinate, as VF, is equal to the rectangle of the col responding absciss A F, and the parameter of that diameter; therefore 4 CA is the parameter of the diameter A G, and since C A is 3 of the parameter, C E is therefore the directrix of the parabola described by the body projected from A, with the velocity acquired by falling from C. - Hence, since this is true for any other point of the curve, the velocity of the projectile in any point of its path is the same that it would have acquired by falling freely from the height of “the directrix to that point. The times of describing the different arcs A V, A V B, are evidently as the parts A K. A. L., of the tangent, or, as the corresponding parts CD, C E, of the directrix; therefore the motion estimated horizontally is uniform. - We shall now briefly apply these principles to the construc- tion and solution of the leading problems in gunnery. The velocity produced by the explosion of a quantity of gun: powder, is, in the preceding theory, conceived to be produced by a fall from a certain height, by the proportion of which its | quantity can be accurately determined. - 420 G U. N. G U N DICTIONARY or MECHANICAL SCIENCE. The height CA, (fig. 2,) for producing the velocity of pro- jection, is called the Impetus. * * The distance A B, between the piece of ordnance and the object, is called the Amplitude or Range. f | elevations. - - The angle contained between the direction of the mortar and , the horizontal plane, is called the angle of Elevation. . . * Problem 1.--A shell is proposed to be thrown from the point A, with the velocity acquired by falling through CA, in order to hit the object B; the direction A D of the projection is required.s (Fig. 2.) . . . Take A-Z = 4 CA, and on A Z describe an arc of a cirele containing: an angle equal to D BA (Euclid, iii. 33); draw: the vertical line B D d, cutting the circle in D and d, and join. Z D, Z d, and A D, A d, then either AD or A d is the direc- tion required. For, produce C. A downward, and draw BF parallel to AD, because. A B touches the circle in A, and A Z cuts it, the angle A D Z is equal to the angle Z. A G = D BA, and the alternate angles Z A D, A D B are equal ; the triangles Z.A D, A D B, are therefore equal, whence B D. : D A : : 1) A : A Z, conse- quently D A" = B D x A Z or B F2 - A F X A Z ~ A E X 4A C. Therefore a parabola, of which A F is a diameter, and A Z its parameter, will pass through B, and conse- quently a shell projected from A, in the direction A D, with the velocity acquired by falling tº through CA, will describe the parabola A v B, and hit theobject B. Fig. 2. Z - H | Z A2 : By similar reasoning; it may be shewn, that the shell, if pro- jected with the same velocity, in the direction Aid, will describe the parabola A V B, and therefore also hit the object B. Cor. 1. When the vertical line through B cuts the circle, it always cuts it in two points D and d, either of which will answer the conditions of the problem. Cor. 2. When the vertical line through b only touches the circle, there is but one directiou A d', in which the body can be projected to hit the object b ; this direction evidently bisects the angle Z.A.B, and from it the directions A D, A d, are equi- distant; also A b is the greatest range. Problem 2.-A shell is proposed to be projected from the point A, in the direction A D, with the velocity acquired by falling through CA; the distance to which it will reach on the line A B is required. (Fig. 2.) Take A Z = 4 C A, and describe the arc Z D A cutting A D in D; through D draw the line B D parallel to AZ, cutting A B in B. Then B is the point to which the shell will reach. The proof is evident from problem 1. Problem 3.−A shell is proposed to be projected from the point A, in the direction A D, in order to hit the object B; the velocity with which it must be projected is required. (Fig. 2.) Draw the vertical line BD, meeting the direction in D; draw A Z parallel to B D, and equal to A. D*-i- D B, and take CA = + AZ; then C A is the fall which will generate the velocity required. The proof of this is also evident. From these constructions, numerical solutions are deduced. Thus, Theorem I. When the line A B is horizontal. 1. The arc Z D A is a semicircle, and the greatest horizontal range A b is E O A; the radius of the circle, – 2 CA; and the direction A d" is - 45°. • . 2. The ranges with different directions are proportional to the sines of twice the angles of elevation. For draw DC, d'O, easily CD = A B. But d'O is the sine of the angle A O d', which is = 2 the Z d'A B, and C D is the Z. A O D, which is - 2 the Z. A Z D = 2 the Z D A B ; and this is true of all other 3. When the direction is the same, the ranges with different velocities are proportional to the squares of the velocities. For the figures being similar, the ranges are as thefalls, and the falls as the squares of the velocities acquired by falling. 4. The height to which the projectile riess above the horizon- tal plane is as the square of the sine of elevation. For v M is = 3; D B, and C A is = + Z A, and Z. A : D B (= HA) : : A D2 : ; radº : sinº AZD (= D A B); therefore C A : v M ; ; rada ; sin” elevation; and v M : W M : : sinº D A B : sin” d A. B. - . - 5. The times of the flights are as the sines of the elevation. For the velocities in the directions A-T); A d, being the same, the times of describing A D, A d, uniformly, (which are the same as the times of describing the parabolas A v B, A V B,) will be as A D, A d, that is, as the sines of the angles A Z D, | AZ d, which are equal to the angles D.A. B., d A. B. Again, the time of the flight is the same as that of falling through D B ; if then D B be computed in feet, the time will evidently be = x/ (D B -- 16) nearly, = } / DB = # M (r x tan E); when r denotes the range, and E the elevation. When E = 45°, then d' b = b A = r ; whence the time is # M r. . - . Theorom II. When the line A B is not horizontal. f Since the angles D B A, A D Z, are equal, it is evident, that when the object B is on an inclined plane, the arc Z D A is less or greater than a semicircle, according as the plane is ascend- ing or descending. It is also plain, that A B : B D :: S,Z A D (= A D B) :: S, D A B, and B D : D A : ; S, D A B : S, A B D ; also, D A : A Z :: S, A D Z (= A B D); therefore A B : A Z ; : S,Z A D x S,AZ D : sinº A B D, whence A B = (A Z x S,Z A D x S, A Z D) -- sin? A B D. Now, if we put a = the inclination of the plane, d = the elevation of the mortar above the plane, e = the elevation above the horizon, r = A B the range, and f = C A the impetus, then, by substitution, the above theorem will become r = 4f x cosin e x sin d x , secº a ; whence f = } r_x sec e x cosec d x cosin a ; also, the time of the flight will be = sec a. sin d. 2 V (f-ºi6}) = seca. sin. d. } M f nearly. º - . The reader will observe, that in the preceding reasonings, no notice has been taken of the effects of the resistance of the air on the motion of projectiles. Now, as this is very consi- derable, especially when they are discharged with great velo- city, the theory requires to be modelled and corrected by experimental investigations, before it can be applied in prac- tice. There are indeed some cases, such as in the throwing of shells, when the velocity does not exceed 400 feet per second, in which the results by the theory do not differ much from the truth. But when the velocity is great, the resistance of the air occasions a diminution of motion so prodigious, as to render tºº * the theory, without the aid of data derived from experiment, of very little use. Thus, a musket-ball, discharged with the ordinary allotment of powder, issues from the piece with the velocity of 1670 feet per second. At the elevation of 45°, it should therefore range 16 miles, whereas it does not range above half a mile. Thus also, a 24 lb. ball, discharged with 16 lbs. of powder, which should range about 16 miles, does not range 3 miles. - Again, the path of a projectile, when the velocity is great, is not parabolical, but is much less incurvated in the ascending than in the descending branch : the greatest range therefore is not made with an elevation of 45° as in vacuo, but with an eleva- tion lower, as the first velocity is greater. Thus it is found, that although the larger shells with small velocities range farthest when projected at an elevation of about 45°, yet the | smaller shells with great velocities range farthest at an eleva- tion not much above 30°. These instances sufficiently shew, that such rules as are deduced from theory alone, without the aid of experiment, are unfit for directing practice. * Practical Gunnery.—Of Projections made on the Horizontal Plane.—Prob. 1. To find the velocity of any shot or shell.— perpendicularly to ZA, and join OD; then O d = A b, and | Rule. Divide double of the weight of the charge of powder by º * \ }|| || N N ſlº) */º/-/*-2 ºlºmon uniºn sº unsu ºn pansiºn * -7. | º ºr | woº wº Zºº |º. - (-) º º Pºzº - º way * mº | - - º N * 7, wo ºr ZººZº. Z. lº º º º - - - - º /* N. C º N - (ſ º - - - - º º | º N º - |-- N º/ . ºzº, º wo zºº” vow.) . º/”7. -Yºz -//zºº ºr ººzoo/* -zºº gº | " - | | º | º | | | | | º % º Z % ºr º G U. N. g UN 421 DICTIONARY OF MECHANICAL SCIENCE. the weight of the shot, both in lbs. Then if the square root of the quotient be multiplied by 1600, the product will be the velo- city, or the number of feet the shot passes over in a second. Or say, As the square root of the weight of the shot is to the square root of double the weight of powder, so is 1600 feet to the first velocity of the shot. Ev. With what velocity will a 13-inch shell, weighing 1961bs. be discharged by 9 lbs. of powder. . V : x 1600 = 485 feet per second, nearly. Ans. : . Or thus, V 196: N/ 18::1600: 485 feet, nearly. Prob. 2. To find the terminal velocity of a ball or shell; that is, the greatest velocity it can acquire by descending through the air, by its own weight. . . - Rule. For balls, the terminal velocity is found by multiplying the square root of the diameter of the ball in inches by 1755; and for shells; by multiplying the square root of the diameter of the shell in inches by 147-3. • Ev. What is the terminal vek city of a 2 lbs. iron ball, its diameter being 2:45 inches. - 175.5 y 245 = 175.5 × 1-56524 = 274,699 feet. Ans. Prob. 3. To find the height from which a body must fall, in vacuo, in order to acquire a given velocity. - Rule. Since the spaces descended by falling bodies are as the square of the velocities, and a fall of 16% feet, or 193 inches, produces a velocity of 32, feet or 386 inches, therefore 386”: the square of the given velocity in inches: : 193: height re- quired in inches. Or, omitting the fractions, if the square of the given velocity in feet be divided by 64, the quotient will be the height required in feet nearly. - - Ea. From what height must a body descend, in order to acquire the velocity of 1670 feet per second. ; . . 16702 - 64–43576 feet. Ans. Prob. 4. To find the greatest range of a ball or shell: and the elevation of the piece to produce that range. Rule. Divide the given initial velocity by the terminal velo- city of the ball or shell, and find the quotient in the first column of the following table; against which, in the second column, will be found the elevation to give the greatest range ; and the corresponding number in the third column, multiplied by the height producing the terminal velocity, will give the greatest range nearly. 2. , 4. Elevatons giving the Greatest Range. º § Range jº. Tange §§ Elevation. divided by i.º. Elevation. divided by velocity. altitude. velocity. - - altitude. O f O / 0.691 || 44 0-3914 || 2:9725 37 15 12346 O'9445 43 15 || 0:585 || 3:226 || 36 30 2.3283 1*198 42 30 0°7787 || 3:4795 35 45 2.522 1'4515 41 45 || 0-9724 || 3.733 35 2.7.157 1 *705 41 1° 1661 3-9865 34 15 2‘9094 19585 | 40 15 1'3598 || 4-24 33 30 3' 1031 2,212 39 30 || 1'5535 4'4935 | 32 45 3'2968 2'4655 38 45 1°7472 || 4-747 32 3°4905 2.719 38 1'9409 || 5° 31 15 3°6842 Ea. What is the greatest range of a 24 lb. iron ball, when discharged with a velocity of 1640 feet, and the elevation to produce that range, the diameter of the ball being 5'6 inches : 175.5 M 5-6 = 415 = the terminal velocity. 415% -- 64 = 2691 = the height producing that velocity. 1640 + 415 = 3.95, which nearly corresponds to 340 15 = the elevation required. - The range in the third column against 34° 15' is 2.9094, and 2.9094 × 2691 = 7829 feet = the greatest range, nearly. Prob. 5. The range of any one elevation being given, to find the range of any other elevation, and the converse.—Rule. As the sine of twice the first elevation is to the sine of twice the second, so is the range at the former to that at the latter, the velocity being the same in both cases. - Prob. 6. The range of one charge being given, to find the range for another charge, or the charge for another range.-- Rule. The ranges at the same elevation are nearly proportional to the charges. - Ea. If, at an elevation of 45°, with a charge of 9 lbs. of pow- der, a shell range 4000 feet, what charge, at the same eleva- tion, will be required to throw it 3000 feet? • * 4000 : 3000 : : 9 : 65 lbs. Ans. Prob. 7. The range and elevation being given, to find the time of the flight.—Rule. As radius is to the tangent of eleva- tion, so is the range in feet, to the square of 4 times the num- ber of seconds taken up in the flight, nearly. - - When the elevation is 45°, then 3 of the square root of the range in feet will be the number of seconds required, nearly. Ea. In what time will a shell range 3000 feet at an eleva- tion of 359? Rad: Tan 359 : : 3000 : 2100.6 . - - # M 2100.6 = 11:45 seconds nearly. Ams. Prob. 8. The range and elevation being given; to find the greatest height to which the shell rises above the horizontal plane.—Rule. As radius is to the tangent of elevation, so is 3. of the range to the height required. - Ex. A shell, when discharged at an elevation of 40°, ranges 3000 feet; what is its greatest height during the flight : . . Rad: Tan 409 : : 750 : 629 feet. Ans. - Prob. 9. The range and elevation being given; to find the impetus.—Rule. As the sine of twice the elevation is to the radius, so is half the range to the impetus. - Ev. With what impetus must a shell be discharged at an elevation of 35° to strike an object at the distance of 3180 feet 2 Sin 70° : Rad : : 1590 : 1629 feet. Ams. Of Projectiles made on an Inclined Plane.-Prob. 10. The in- clination of the plane, and the impetus and elevation of the piece being given, to find the range.—Rule. Add together twice the log. secant of the plane’s inclination, the log. sine of the elevation above the plane, the log. co-sine of the elevation above the horizon, and the log. of four times the impetus; then will the sum be the log. of the range. ... • Ev. How far will a shot range on a plane which ascends 10°, and on another which descends 10°, the impetus being 2000 feet, and the elevation of the piece 32° 30' * The elevation above the plane, in the first case, is 22° 30', and in the second 42° 30'. * , * . 1st, For the ascending plane. 2dly, For the descending plane. 10°. . . . . . . . 2 Sec . . 0-01.3297 || 10°. . . . . . . . 2 Sec . . 0-013297 22° 30' ... sin . . . . 9'582840 ||22° 30' . . . . sin . . . . 9.829683 32° 30' . cosin ... 9.926029 || 32° 30' .... cosin ... 9.926029 8000 . . . . . . log. . . . . 3.903090 ||8000 . . . . . . log..... 3.903090 Range = 2662 feet = 3.425256||Range = 4700 feet = 3-672099 Prob. 11. The inclination of the plane, the range and eleva- tion being given, to find the impetus.—Rule. Add together twice the log. co-sine of the plane's inclination, the log. co- secant of the elevation above the plane, the log. secant of the elevation above the horizon, and the log, of 3 of the range; then will the sum be the log. of the impetus. With what impetus must a shell be discharged to strike an object at the distance of 2662 feet on an inclined plane which ascends 109, the elevation of the mortar being 32°30'? Plane’s inclination. ......... 10°. . . . . . 2 COs . . 10'986703 Elevation above the plane .. 22° 30'. . cosec ... 0-417160 Elevation above the horizon... 32° 30'. . sec . . . . 0-073971 % of the range. . . . . . . . . . . . . . 665-5. ... log. ... 2.823148 Impetus = 2000 feet, nearly – 3'300982 - GUNPOWDER, a chemical mixture of nitre, charcoal, and sulphur, for the purpose of producing an explosive force by combustion, and thus communicating to guns of every caliber a prodigious power of projection. The first person who is said to have been acquainted with the mature and effects of a combination of these three materials in a certain proportion to each other was Roger Bacon. In his treatise “De Secretis Operibus Artis et Naturae et de Nullitate Magiae,” cap. vi. published at Oxford about 1216, he informs us, that from salt- petre and other ingredients, we are able to make a fire that shall burn at any distance we please, which “other ingre- dients,” it appears from some of his other manuscripts, were sulphur and charcoal. It was not, however, for a considerable 5 P Å22 G U N G U N DICTIONARY OF MECHANICAL SCIENCE. time aſter this date that gunpowder became generally known; indeed it is very difficult, amongst the various contradictory accounts, to affix any precise date to this invention. Robins, in his “Gunnery,” considers it as known before the time of Bacon, and that this philosopher mentions it not as a new dis- covery, but as the application of an old principle to military purposes, in which it had not been before employed. The pro- portions of the above ingredients, according to the best modern practice, is as follows; viz. 75 parts of nitre or saltpetre, 15 of The specific gravity of which composition, at a mean, as stated by Count Rumford, is about | pressed, for a difference in expansion makes a difference in the charcoal, and 10 of sulphur. 0-868, that of water being 1. - : The method of ascertaining the strength of gunpowder is by a machine called an eprouvette, of which there are various constructions; but it commonly consists of a small strong barrel, in which a determinate quantity of the powder is fired, and the force of expansion is measured by the action excited on a strong spring or a great weight. Another method often adopted, is to fire a very heavy ball from a short mortar with a given weight of the powder, and to find the range of projection. The French eprouvette for government powder is a mortar of seven inches (French) in caliber, which with three ounces of powder should throw a copper globe of sixty pounds weight to the distance of 300 feet. No powder is admitted which does not answer this trial. Both these methods have been objected to : the former because the spring is moved by the instantane- ous stroke of the flame, and not by its continued pressure, which is somewhat different; and the other on account of the tediousness attending its use, when a large number of barrels of powder are to be tried. Another method, which unites accuracy with despatch, is to suspend a small cannon as a pendulum, to fire with powder only, and to judge of the force of explosion by that of the recoil, which in this circumstance is a greater or less arc of a circle. That which Dr. Hutton em- ployed on this principle, was a small cannon about one inch in the bore, the charge of which is two ounces of powder. The cause of the explosive force of fired gunpowder has been much investigated; but it is now generally allowed to be chiefly owing to the sudden generation of a quantity of gas or elastic vapour. To determine the elasticity and quantity of this elastic vapour, produced from a given quantity of powder, Mr. Robins premises, that its elasticity is equally increased by heat and diminished by cold, as that of common air, (which is confirmed by Dr. Hutton's late experiments :) and conse- quently its weight is the same with the weight of an equal bulk of air at the same elasticity and temperature. Hence, and from direct experiments, he concludes, that the elastic fluid produced by the firing of gunpowder is nearly three-tenths of the weight of the powder itself, which, expanded to the rarity of common air, is about 244 times the bulk of the powder. Hence it would follow, that the mere conversion of confined powder into elastic vapour, would exert against the sides of the containing vessel an expansive force 244 times greater than the elasticity of common air, or, in other words, than the pressure of the atmosphere. But to this is to be superadded all the increase of expansive power produced by the heat generated, which is certainly very intense, though its exact degree cannot be ascertained. Supposing it to be equal to the full heat of red-hot iron, this would increase the expansion of common air (and also of all gases) about four times, which in the present instance would increase the 244 to nearly 1000; so that in a general way it may be assumed, that the expansive force of closely confined powder at the instant of firing is 1000 times greater than the pressure of common air: and this latter is known to press with the weight of fourteen pounds and a quarter on every inch; the force of explosion of gunpowder is 1000 times this, or 14750 pounds, or about six tons and a half on every square inch. This enormous force, however, is diminished in proportion as the elastic fluid dilates, being only half the strength when it occupies a double space, one- third of the strength when in a triple space, and so on. Mr. Robins found that the strength of powder is the same in all variations of the density of the atmosphere, but not so in every state of moisture, being much impaired by a damp air, or with powder, which is become damp with careless keep- ing, or any other cause; so that the same powder which will discharge a bullet at the rate of 1700 feet in a second in dry air, will only propel it at the rate of 1200 feet when the air is fully moist; and a similar difference holds between dry and moist powder. Gunpowder is reckoned to explode at about 6000 of Fahrenheit's thermometer, but if heated to a degree just below that of faint redness, the sulphur will mostly burn | off, leaving the charcoal unaltered. Wightman, , a gun-maker at Malton, in Yorkshire, says, the only certain way of computing the charge of powder for a fowling-piece is by weight, and not by the space it occupies in the barrel; and also the quality of the barrel should be ex- quantity required for a charge : for instance, the Damascus and common barrels, on account of their less expansibility than the twisted barrels, shoot equally strong with the latter When the charge of powder is reduced four grains; for it must be obvious to every one, that the shot could not be dislodged with equal force when the sides of the barrel yield to the sud- den expansion of the exploded powder; and here I may add, that the shot travels with a much greater velocity than the rarefaction that moved it, which shews that the shot receives no accumulation of force by the quantity of powder which is put into the barrel, more than what is fired in the first instant, as the shot is propelled by the first rush of the air on the com- bustion of the powder. - The accompanying scale, he adds, is the result of trials made on several hundred guns. - * Barrels are not so much distressed by firing balls, if the bore is cylindrical ; the shot having a tendency to occupy a greater space, and therefore pressing hard against the sides of the barrel. In proof of this, the barrels of the guns used with shot are soon leaded, owing to the friction of the shot; but this is not the case when balls are used. The greatest objection, however, to the use of barrels of fowling-pieces for ball shoot- ing is, that they are seldom sufficiently strong in the fore-end to prevent a vibratory motion, in which case the ball is thrown without any degree of precision. A ball of 19 to the pound exactly fits a 5-8ths bore, but a ball of 20 pounds, encircled in a thin piece of leather, is preferable. - - The Damascus barrels are decidedly superior to the stubs twisted, or any other ; the metal being stronger in texture, uniting better in welding, having little or no recoil, requiring a less charge of powder, and being more beautiful to the view. The percussion-lock has every advantage over the flint-look, namely, there is a less liability of accident by it, not being necessary to prime before loading, and the cock may be always kept on the cap except at the moment of firing, which prevents the gun going off at half-cock; and if the gun is brought home loaded, by taking off the cap (which is the priming) there is no danger of its being fired by the foolishness of servants or others; and it is a fact, known to every observer of the per- cussion-gun, that they kill at ten yards farther than a flint-gun, and that about one-quarter less powder is used for a charge, owing to the complete and instantaneous combustion of the whole charge of powder; and that there is no loss of force through the touch-hole, as in the flint-guns; and also, that they receive the additional strength of the priming. - - —l- & Charge of Charge of • . . º - º: p. for a p. for a Qº of º © Flint Gun. |Percussion do. ºve. tº 5–8 inch. 1 dram. # dram. 13 OZ 30 yds. - 14 # do. 40 1% 1% do. 50 1% 1+ do. 60 1} 1 1} Oz. 30 1} 1% do. 40 # 1; do. 50 2 1} do. 60 3-4 1} 1} 1; oz 30 1% 1} do. 40 2 l; do. 50 , 2} 2 do. 60. G U N G U N 423 D I CTIONARY OF MECHANICAL SCIENCE. ** To Prove Gunpowder,--There are seve: always of doing this. 1. By sight; thus if it be too black, it is a sign that it is moist. or else that it has too much charcoal in it; so also if rubbed upon white paper it blackens it more than good powder does; but if it be of a kind of azure colour, somewhat inclining to red, it is a sign of good powder. 2. By touching; for if in crushing it with the fingers' ends, the grains break easily and turn into dust, without feeling hard, it has not too much coal in it: or if, in pressing it under the fingers upon a smooth hard board, some grains feel harder than the rest, it is a sign the sulphur is not well mixed with the nitre. By firing a small heap of it on a clean board, and attending nicely to the flame and smoke it produces, and to the mark it leaves behind on the board.—-There are other contrivances made use of, such as powder triers, acting by a spring, commonly sold at the shops, as the eprouvette. º . To Recover damaged Powder.—Put part of the powder on a sail-cloth, to which add an equal weight of what is good : then mingle it well together, dry it in the sun, and barrel it up, keeping it in a dry and proper place. If it be very bad, re- store it by moistening it with vinegar, water, urine, or brandy, then beat it fine, sift it, and to every pound add an ounce, or an ounce and a half, or two ounces (according as it is de- cayed ) of melted nitre, and afterwards these ingredients are to be moistened and well mixed. But the operation of beat- ing, or any species of friction, is extremely hazardous, and though we relate the method, we do not recommend the prac- tice of this experiment. + GUNPowder and Combustibles. The laws respecting the manufacture and sale of these may be briefly expressed. No person shalſ make gunpowder but in the regular manufacto- ries established at the time of making the statute 12 George III. c. 61, or licensed by the sessions. Only forty pounds of powder is to be made at one time under one pair of stones. Not more than forty hundred weight to be dried at one time in one stove. Not more than twenty-five barrels to be carried in any land carriage, not more than two hundred barrels by water, unless by Sea or coastwise, each barrel not to contain more than one hundred pounds. No dealer to keep more than two hundred pounds of powder, nor any person, not a dealer, more than fifty pounds in the cities of London and Westminster, or within three miles thereof, or within any other city, borough, or market-town, or one mile thereof, or within two miles of the king's palaces or magazines, or half a mile of any parish church, on pain of forfeiture, and two shillings per pound, ex- cept in licensed mills, or to the amount of three hundred pounds for the use of collieries, within two hundred yards of them. GUNTER, EDMUND, an excellent English mathematician, who flourished in the reign of James I. and distinguished him- self by his inventions, which have never yet been superseded, though some of them have been subsequently much improved. GUNTER’s Chain, the chain in common use for measuring land according to the true or statute measure; so called from the name of its inventor. 22 yards, or four poles of five yards and a half each ; and it is divided into 100 links of 7-92 inches each ; 100,000 square links make one acre. GUNTER's Line, a logarithmic line usually graduated upon scales, sectors, &c. * It is also called the Line of Lines and Line of Numbers, being only the logarithms graduated upon a ruler, which therefore serves to solve problems instrumentally, in the same manner as logarithms do it arithmetically . It is usually divi- ded into a hundred parts, every tenth of which is numbered, beginning with 1, and ending with 10; so that if the first great division, marked 1, stand for one-tenth of any integer, the next division, marked 2, will stand for two-tenths; 3, three- tenths, and so on ; and the intermediate division will in like manner represent one-hundreth parts of an integer. If each of the great divisions represent 10 integers, then will the lesser divisions stand for integers; and if the great divisions be spu- posed each 100, the subdivisions will be each 10. Use of Gunter’s Line.—1. To find the product of two numbers. From 1 extend the compass to the multiplier; and the same extent, applied the same way from the multiplicand, will reach The length of the chain is 66 feet, or to the product.—Thus if the product of 4 and 8 be required, extend the compasses from 1 to 4; and that extent laid from 8 the same way, will reach to 32, their product. 2. To divide one number by another.—The extent from the di- visor to unity will reach from the dividend to the quotient; thus, to divide 36 by 4, extend the compasses from 4 to 1, and the same extent will reach from 36 to 9, the quotient sought. 3. To find a fourth proportional to three given numbers.-Sup- pose the numbers 6,8,9: extend the compasses from 6 to 8; and this extent, laid from 9 the same way, will reach to 12, the fourth proportional required. x . 4. To find a mean proportional between any two given numbers. —Suppose 8 and 32: extend the compasses from 8, in the left- hand part of the line, to 32 in the right; then bisecting this distance, its half will reach from 8 forward, or from 32 back- ward, to 16, the mean proportional sought. 5. To extract the square root of a number.—Suppose 25: bisect the distance between 1 on the scale and "the point representing 25; then half of this distance, set off from 1, will give the point representing the root 5. In the same manner, the cube root, or that of any higher power, may be found by dividing the distance on the line, between 1 and the given number, into as many equal parts as the index of the power expresses; then one of those parts set from 1, will find the point representing the root required. GUNTER’s Quadrant, is a quadrant made of wood, brass, or Some other substance ; being a kind of stereographic projec- tion on the plane of the equinoctial, the eye being supposed in one of the poles; so that the tropic, ecliptic, and horizon form the arches of circles, but the hour circles are other curves drawn by means of several altitudes of the sun for some parti- cular latitude every year. This instrument is used to find the hour of the day, the sun’s azimuth, &c. and other common problems of the sphere or globe; as also to take the altitude of an object in degrees. GUNTER’s Scale, usually called by seamen, the Gunter, is a large plain scale, having various lines upon it, of great use in working the cases or questions in navigation. This scale is usually two feet long, and about an inch and a half broad, with various lines upon it both natural and logarithmic, relat- ing to trigonometry, navigation, &c. On the one side are the natural lines, and on the other the artificial or logarithmic ones. The former side is first divided into inches and tenths, and numbered from one to twenty-four inches, running the whole length near one edge. One half of the length of this side consists of two plane diagonal scales, for taking off dimen- sions for three places of figures. On the other half of this side are contained various lines relating to trigonometry, as per formed by natural numbers, and marked thus ; viz. - Rhumb, the rhumbs, or points of the compass; Chord, the line of chords ; Sine, the line of sines; Tang., the tangents; * , w e S. T., the semi-tangents; and at the other end of this half are, - Leag., leagues, or equal parts; Rhumb, another line of rhumbs. M. L., miles of longitude. Chor., another line of chords. Also in the middle of this foot are L and P, two other lines of equal parts: and all these lines on this side of the scale serve for drawing or laying down the figures to the cases in trigonometry and navigation. On the other side of the scale are the following artificial or logarithmic lines, which serve for working or resolving those cases; viz. S. R., the sine rhumbs; V. S., the versed sines; T. R., the tangent rhumbs; Tang., the tangents; Numb., line of numbers; Meri., meridional parts ; Sine, sines; E. P., equal parts. GUNWALE, or GUNNEL of A SHIP, is that piece of timber which reaches on either side of the ship, from the half. deck to the fore-castle, being the uppermost bend, which finishes the upper works of the hull in that part, and wherein they put the '424 G Y M G Y M DICTIONARY of MECHANICAL scIENCE. stanchions which support the waist-trees. This is called the gunwale, whether there be guns in the ship or not. The lower part of any port, where any ordnance are, is also termed the gunwale. . . • * • GUST, a sudden and violent squall of wind, bursting from the hills upon the sea, so as to endanger the shipping near the shore. These are peculiar to some coasts, as those of South Barbary and Guinea. - - . GUT, in the West India islands, particularly in the island of Christopher’s, or St. Kitt's, is a term for the opening of a river or brook, such river or brook also being often so called. GUTTA SerenA, a disease in which the patient, without any apparent fault in the eye, is entirely deprived of sight. GUTTER-Ledge, a cross bar laid along the middle of a large hatchway in some vessels, to support the covers, and enable them the better to sustain any weighty body which may be laid on them. - Gutters, in Architecture, a kind of canals in the roofs of houses, serving to receive and carry off the rain. - GUTTURAL, a term applied to letters or sounds pronounced or formed as it were in the throat. - GUY, a rope used to keep steady any weighty body from bearing or falling against the ship's side while it is hoisting or lowering, particularly when the ship is shaken by a tempes- tuous Sea. - - GUY, is also the name of a tackle, used to confine a boom forward when a vessel is going large, and to prevent the sail from gybing by any accidental change of the wind or course, which would endanger the springing of the boom, or perhaps the upsetting of the vessel. • - GUY, is likewise a large slack rope, extending from the lead of the main-mast to the head of the fore-mast, and having. two or three large blocks fastened to it; it is used to sustain a tackle to load or unload a ship with, and is accordingly removed as soon as that operation is finished. GYBING, the art of shifting any boom-sail from one side of the vessel to the other. In order to understand this operation ‘more clearly, it is necessary to remark, that by a boom-sail is meant any sail whose bottom is extended by a boom, the fore- end of which is hooked to its respective mast, so as to swing occasionally on either side of the vessel, describing an arch, of which the mast will be the centre. As the wind or the course changes, it also becomes frequently necessary to change the position of the boom, together with its sail, which is accord- ingly shifted to the other side of the vessel, as a door turns upon its hinges. The boom is pushed out by the effort of the wind upon the sail, and is kept in a proper situation by a strong tackle communicating with the vessel’s stem, and called the sheet. It is also confined on the forepart by another tackle called the guy. - GYMNASIA, in ancient Greece, were edifices consisting of a great many separate parts or buildings for the accommoda- tion of professors of the sciences or arts, and their hearers or pupils. Vitruvius, the Roman architect, gives the plan of the area of a Grecian Gymnasia, which the reader will find in his Architecture, or in Potter's Grecian Antiquities, vol. i. p. 45, Dunbar's edition. The parts of the Gymnasia were, 1st. The porticos or side buildings, furnished with seats, and fit for study or discourse, where the scholars probably met. 2d. The Ephebeam, where the youths exercised, or in which they assembled to fix on their sports and rewards. 3d. The undressing room. 4th. The place in which those who were to wrestle, or who had bathed, were anointed. 5th. The place where the dust was kept for besprinkling those who had been anointed. 6th. The Gymnasium, or place of wrestling. 7th. The tennis court, or ball ground. 8th. The discus and leaping ground. 9th. The Xysta, designed for the exercises of the wrestlers when the inclemency of the weather did not allow of practice in the open air. 10th. The baths, either hot or cold, for the refreshment of the combatants after their labour and toil. At Sparta, where nature was every thing, the sexes had one common bath; but in all other cities of Greece there were ‘distinct baths for females. 11th. The stadium was the place of general exercise for performers and audience; and being built with benches rising one above another, allowed vast multitudes to assemble and witness the national pastimes. | young men were then practising there. GYMNASTICS. This word, derived from the Greek, com- prehends all those athletic exercises by which the ancients rendered the body pliant and healthy, and enabled the muscle to do their offices with treble effect. - - - The principal exercises we here notice, as belonging to the ancient games, were leaping, running, throwing, darting, wrest- ling, boaring, and perhaps swimming. g Swiftness in running was one of the most excellent endow- ments a man could be blessed with, as is plain from Homer's constant character of the swift-footed Achilles. Saul and Jonathan were 2 * . “Swifter than eagles, and stronger than lions.” - The ancients practised leaping with oval weights placed upon their shoulders, or carried in their hands. - The cestus used on the hands in boxing, was the invention of Amycus, king of the Bebrycians, who was contemporary with: the Argonauts, according to Clemens of Alexandria. Thesus invented the art of wrestling, in which the antagonists had their bodies anointed with oil. In addition to these, the ancients had horse, chariot, and naval races, with swimming and diving, upon which we forbear to offer any description, but proceed at once to the modern Gymnastics, framed towards the close of the last century at Schnepfeuthal, a small town near Gotha, under the direction of Salzman, and subsequently improved, augmented, and systematically arranged by Gutz- muth, who published the first modern treatise on the subject in 1793. Gutzmuth not only attracted attention towards the im- portance of a systematic physical education; but in Denmark, in 1803, those exercises became national, inasmuch as 3000 Since that period, the Danish government issued an order, allotting 200 square yards of ground to every public school, as a Gymnasium. In 1810 Gutzmuth established his Gymnastics in Prussia, by authority of and under the protection of the government. M. Jahn, who undertook the management of this business in Berlin, soon promulgated Gymnastics in various parts of Germany. Gutz- muth published, in 1817, a complete system of Gymnastics, and the drawings, figs. 5, 6, 7, and 8, of the plate on Gymnastic Exercises, are taken from “A Military Officer’s” abridgment of Gutzmuth's work. . In this country we have several professors of Gymnastics—of whom it will only be necessary to quote Capt. Clias, whose “Elementary Course of Gymnastic Exercises,” illustrated by seventy engravings, is at once the most complete and systema- tic display of the physical powers of man that we have ever seen. In the sequel of this article we shall not attempt to draw a parallel between the abridgment of Gutzmuth's work and that of Captain Clias; but from both publications we will point out the exercises, and abstract such parts of their instructions as may serve the illustration of this subject in our own work. In the division of Capt. Clias’s work, the whole system of Gymnastics is reduced to four grand divisions,—first, as appli- cable to the lower extremities of the body; secondly, as belong- ing to the superior extremities; thirdly, complicated exercises, which require the united assistance of the muscles of the trunk and limbs; and fourthly, swimming. g - Swimming we reserve till we come to letter S.–article Swi MMING. - * The “ Instructions” by the “Military Officer,” as reduced from Gutzmuth's book, and taught and practised in Germany, are the following. - Note.—The plan of the ground for exercise, which should always be designed by the master. - - I. Walking : Position of the Body in Walking.—Directions. The position of the body must be upright and unconstrained; the breast thrown well forward, and square to the front; and the stomach drawn in a little, but not so much as to prevent a free breathing. The shoulders must be drawn back, and kept at an equal height. The arms must have a gentle, but perfectly free and natural motion by the side of the body. The head should be very upright, but without any stiffness; and ought to have a free motion from right to left, or upwards and down- wards, as occasion may require, without causing any material alteration in the position of the body. The knees must neither bend too much, nor appear stiff. The toes must be turned out so as to form about half a right angle with the direction-line in Cl - $ 4. - 4. * * ; : , * * * * : GYMNAs TIC EXERCISE s, ANCIENT AND MODERN. . .” -Y. s - … .º.º.º.º. . S. ' > =3& - Ž9. -- - º ---. \ Aazizza with ‘, Aft). • ‘º § .7 72, º .5 Ancient mode of marting. l & 27- W \ º tº: º -& &l z H Published by Fisher, son &c. cza, Lozada A226. NS | *** * * *-*** -Z , . . . " . - *** * * ~~~ • *-ſ _Pra -- - ...'- - - - ---e--- - - -- - - - iºn & Eºrar: ºr 1. º {} } ! y i! : | --~~~~ Jºr.xx... G Y M G Y M DICTIONARY OF MECHANICAL SCIENGE. S 425 which the person is walking; and great care should be taken not to throw them upwards, but to keep the sole of the foot at the concluding part of the step, nearly parallel with the ground. The weight of the body should rest more upon the balls of the toes than upon the heels; by which means the whole position is rendered firm. II. Running, in which the breast must be thrown well for- ward, and kept perfectly free. The upper parts of the arms are kept almost close to the sides of the body; the elbows bent, so that both parts of the arm may form, at this place, an acute angle ; for the arms ought only to move to and fro in a very trifling degree, in order that the muscles connected with the breast may remain, as much as possible, at rest. At every step the knees are stretched out, and the tread must neither be entirely with the balls of the toes, since this would affect the calves too powerfully, nor yet with the whole sole of the foot. Precautions.—Proceed gradually, as in all exercise. Choose a time when the air is cool. Take off your coat at the com- mencement of the exercise, and resume it the instant it is com- pleted. Let the breast be either quite exposed, or very thinly covered. Wear a very light covering upon the head; a straw hat is best. The teacher should observe the runners, and let each cease as soon as a strong perspiration appears, and the breath becomes very short.—With these precautions, no fear need be entertained of the longest run. Preparatory Exercises.—1. The teacher moves forward with his young pupils, at a moderate running pace, for five minutes. After they have frequently run over the ground, in this stated time, it must be gradually reduced; for instance, first to four, and then to three minutes. 2. Another piece of ground should be run over, at a mode-, rate pace, during ten minutes, which time must also be gra- dually reduced as before. In these exercises, the teacher must not reduce the stated times, so as to render the exercise too violent for the weakest of his pupils. He should also pay particular attention to their relative strength, in order to judge which of them are capable of completing the more difficult exercises. 3. In order to practise the pupils in turning, the teacher should form a figure upon the exercise-ground, similar to the annexed:—In running through this, they would be necessi-g tated to turn the body suddenly in different directions. The direction to be taken by the runners, must be frequently changed by the teacher. They may also run in pairs, thus:–Two, of nearly equal strength, start together at a, the one taking the direction of a, e,f, to d, the other, that of a, e, b: he that reaches d first is the winner. The distance from f to h, should be about fifty feet, and that of a, d, about twenty-five feet. Running is divided into the quick run, and the long run, which need no explanation: the only faults to be avoided are, that the steps be neither too long nor too slow, too short nor too uick. ë q III. Leaping, an excellent exercise for giving strength and agility to the lower members, has, as its preparatory exercises, the hop walk, the hop run, hopping, striking of the lower parts of the back with the feet, singly or doubly; and raising the knees. Af - Leaping is then divided into the high leap without a run, the high leap with a run, the long leap, the jump with the run, spring, and descent, the deep leap, performed either with or without the assistance of the hands. as K2 ÇO. (2/ C f: 62 IV. Those exercises for augmenting the muscular powers of the body and limbs, as performed on stands by Gutzmuth, are represented in figs. 6 and 7 of the plate Gymnastics, and if possible, they should be under cover, that the learners may be sheltered from either the rain or sun. That shewn in fig. 6, is about five feet high, two feet in width, and of any convenient length; the upper surface of the bars a, b, c, and d, is rounded off so as to be more easily grasped by the hand. The other, in fig. 7, consists of four posts, a, b, c, d, of which b and c are about fifteen feet distant from each other, the one six, and the other seven feet high. The latter support a cross-piece, e,f, which is six inchcs deep, its lower side three inches wide, and its upper one about two ; altogether it is shaped like the upper part of the rail of an ordinary staircase; g, h, and i, k, are two poles made of fir, eight feet long, and from two to two inches and a half thick: made round and smooth, and of different heights, for the convenience of the learners. Evercise 1. The learner raises himself into the position shewn at No. 1, upon the stand a, b, c, d, and swings his legs back- ward and forward, the higher the better, as long as he possibly can; during which motion his feet will nearly describe the semicircle e, f, g. - 2. When in the last position, the learner makes a jump, as it were, with his hands forward, and repeats it until he arrives at the end of the stand; whence he commences jumping back- ward as far as the other extremity. This, and the preceding, are two excellent exercises for strengthening the wrists. 3. The learner, after having raised himself into the position required in Ex. 1, lowers his body so as to bring his head nearly on a level with his elbows, which must be kept exactly over the bars. See No. 2. The most difficult part of the exercise follows; which consists in raising himself again into his former position. This exercise, which he should repeat as often as possible, is perhaps the best of any for strengthening the muscles of the chest, and particularly those which are con- nected with the shoulders, 4. As many of the learners place themselves in a row under the bar e,f, fig. 7, as can find convenient room; the tallest are nearest to the end f. The others who are not able to share in this exercise, help their companions up. so that they may seize the bar with both hands, and then leave them in that position. Each now supports his own weight with arms at full length, as long as he possibly can ; which forms the first part of this exercise. The second is more difficult: it consists in keeping the elbows so much bent, that one shoulder remains close under the bar. Since it is not in the power of every beginner to raise himself to this position, the teacher must assist him until the required height is attained ; it is sufficient for him to remain there but a short time at first. The exercise is render- ed more lively by letting the learners try who can hang in this manner longest; but the teacher must prevent any one from overdoing it. 5. The hands are placed upon the bar, over opposite sides, as seen in No. 1. At another time they may be placed both on the same side. The learner now draws himself so much up- ward, as to be able to see over the bar, keeping the legs and feet closed and stretched out. He then lowers himself to the full length of his arms, and again raises his body. This exer- cise is very trying if often repeated. . Most persons will go through it three, six, or perhaps nine times, but few reach the eighteenth or twenty-fourth time. It must not be carried too far, for the muscles are to be strengthèned, not relaxed. These two exercises should be frequently repeated, since they wonderfully increase the muscular powers, and greatly facilitate the succeeding exercises. 6. The learner hangs with his hands upon the bar, as before, and then raises and lowers the legs alternately. See No. 2. The hands are fixed on both sides, and at a little distance from each other; the elbows are very much bent; one shoulder is immediately under the bar, and the upper parts of the arms lie close to the body. The head now sinks backward, and at the same time the feet are raised so as to touch each other gently over the bar. From this they again sink into the hanging posi- tion. Beginners who have not thoroughly practised the two preceding exercises, find this one very difficult: some make a preparatory swing with the feet to assist them; but this is not correct, since the exercise ought to be performed entirely through the muscular force of the arms, back, &c. It can be repeated six, nine, twelve, eighteen, twenty-four, and even thirty times. The teacher is again recommended to prevent any one from overdoing the exercise: the pupils should not be impatient, but overcome every difficulty by practice alone. 7. Let the feet, when in the position of No. 2, as required in the preceding exercise, cling close to each other over the bar, and remain as long as possible in this position. The learners try to excel one another in this exercise. 5 Q 426 G Y M & Y M > DICTIONARY OF MECHANICAL SCIENCE. 8. Suppose the body to be in the last-mentioned position, I viz. No. 2. Throw the right arm and right leg quickly over the bar, so as to hang to it by the elbow and knee joints, as seen in No. 3. Change the position with the same quickness by throwing the left leg and arm over the bar, in order to rest the other side. Finally, the body may be made to hang by the right leg and left arm, and vice versa. This exercise, which is performed upon the round bars g, h, and i, k, is rendered very pretty, by the position of the body and limbs being continually varied, and is very useful as a preparatory one to climbing: 9. Suppose the body to be again in the position of No. 2. Commence moving the hands one before the other, either towards e or f, and let the feet follow, either sliding along the bar, or what is much better, alternately changing like the hands, and retaining, in some measure, a similar hold. Con- tinue moving along the bar in this manner, as long as your strength will permit. - 10. The body hangs to the bar by the hands, placed as shewn at No. 4; these are then moved either forward or back- ward alternately as long as possible. This exercise is faulty when the arms hang straight and slack; or when the feet, instead of being quiet and close together, are violently drawn up and down. It may be varied by the learner’s placing him- self in front of the bar, hanging by both hands, and moving the latter alternately sideways. 11. When a person is in the position of No. 3, it is very easy for him to throw the left leg over the bar and across the right one; then let to go the arms entirely, and hang by the knee joints only. This exercise is perfectly safe, strengthens the knee joints, and is often useful in climbing. 12. The body being in the position of No. 2, the learner endeavours to sit upon the bar. The first attempts frequently fail, since some strength and agility are required. The easiest way of doing it is thus: suppose you wish, when in the posi- tion of No. 2, to get up on your right side of the bar; take a fast hold by the right knee joint, grasp firmly with the right hand, and bring the left arm over the bar so that the latter may be exactly under the armpit. From this position, the required or riding one is obtained with very little trouble. -- 13. When a person is in the riding position upon the bar, it is very easy for him to turn towards the front of the bar e,f, viz. by supporting himself upon one thigh, while the other leg hangs down. He then moves along the bar sideways, by rais- ing his body with his hands, which are placed on the bar on each side of him. This exercise is very useful in practising a person to proceed a great way along a high beam. 14. The learner is in front of the bar, with his hands resting upon it, as in No. 5; he then removes his hands either to the right or left, and supports himself, in this manner, as far as he can along the bar. - 15. Suppose a person to be supporting himself by the hands | upon the bar, as before, No. 5; he then throws his head down forward, and dives, as it were ; the middle of the body rests momentarily upon the bar, the feet swing upward, the whole. person turns completely round, and the feet come to the ground. This is swinging round the bar forward; it is more difficult, but prettier, backward. Supported by the hands as before, the learner swings his feet once or twice backward and forward ; when in the last swing he throws them quickly forward under- neath the bar, forcing them upward on the opposite side, and then passes them over. See No. 6. In this he also rests momentarily with the middle of the body upon the bar, and then returns to his first position. This swing round the bar backward is not easy at first ; it requires a good deal of agility and exertion of the elastic force. The exercise should always be performed upon a smooth round bar, as g, h, or i, k. Exer- cises of this kind admit of numerous variations, and boys soon find them out; but the teacher should always stand by to observe them, and to give his assistance to any one who may require it. g V. Vaulting, or raising the body from the ground quickly by a spring, and giving it at the same time such a swing by lean- ing the hands upon a fixed object, and poising the body if necessary, that the leap may be completed with facility. This exercise augments the flexibility of the arms and legs; it aug- ments also the muscular powers of the body, and is serviceable in horsemanship, coursing, and numerous pastimes of youth. VI. Leaping with a Pole, as the high leap, the long leap, the deep leap—all of which are a species of vaulting, in which the leaper carries a pole with him, which he places exactly upon any spot that offers itself, and upon which he supports himself during the leap. . VII. Balancing, the art of preserving a just equilibrium of the body in whatever position it may be placed, is a pleasing exercise confined to the lower extremities, or legs, and may be performed on the ground or on a bar. The balancing bar consists of the stem of a tall and straight- grown fir, planed off quite round, about 60 feet in length, and placed in a level direction; see a, b, in the following figure, Its thickest end a, is supported by a post c, and may be raised or lowered at pleasure, by means of an iron peg, made to pass through the holes bored in the sides of the post. The stand d supports the bar somewhere about its centre, which can also be raised or lowered in this place. That part of the bar from d to b, remains without support, and consequently wavers when any weight is placed upon it. The upper surface of the bar is usually about 3 feet above the ground : it may be flat- tened a little about a foot from the extremity b. The teacher conducts the pupil, by the hand, along the bar, a few times. The latter must keep his feet turned outward, A & 7 . - - - 2 º 3} *º- 6 20 40 Jo co l t T- Aº’4” and his body in an upright position. Little boys soon accus- tom themselves to walk upon the wavering end of the bar; they gradually take more courage, and learn to preserve their balance. After a short time, the teacher begins to give the pupil less assistance; instead of holding him fast by the arm, he now only allows him to touch the point of his finger, and at last only places his hand before him. t - * 2. The learner walks along the bar, without the assistance of: the teacher, (see No. 1,) who, however, remains by his side, at first, in order to observe the position of his body, and the placing of his feet, and also to assist him if absolutely required. • * . ** 3. As soon as the learner is able to walk courageously along the bar, preserving a good position of the body, and also to spring off without falling, whenever he may have lost his balance, the teacher must render his walk more difficult, by placing obstacles, such as large stones, upon the bar, which he is either to step over, or to lift up; or he may hold a small G Y M. G Y M DICTIONARY OF MECHANICAL SCIENCE. 427 stick before him, about the height of his knee, and make him step over it. See No. 2. The exercise is made more difficult by obliging the learner to hold his hands across his breast, instead of using them to assist in keeping his balance. 4. Hitherto the learner has been accustomed to walk from a to 5, and to jump off from the latter extremity; but the teacher now makes him turn round at b, and return to a. He ought, however, to have previously learned to turn himself well upon the thick end of the bar. - * 5. The pupil walks backward upon the bar; an exercise which is not at all so difficult as it appears, if he have acquired sufficient expertness in the preceding ones. 6. Two learners meet upon the bar, and wish to pass each other. They hold one another fast by the arms, and advance breast to breast. Each places his right foot forward, close to that of his comrade, across the bar. See No. 3. They count 1, 2, 3, and turn completely round one another at the word three, each making a step with his left foot round the right one of his comrade, as the two learners have already done at No. 4. The two learners represented at No. 5, are turning themselves round after having placed the left foot in front; and have completed the turn, except the withdrawing of this foot. 7. This is a repetition of a preparatory exercise to vaulting, applied to the balancing bar. When performed upon the wavering part of the bar, it is an excellent exercise in balanc- ing. The learner should, in repeating it, advance nearer to the end b of the bar. 8. This is a repetition of some preparatory exercises, viz. the sitting down and standing up on one leg, applied to the balancing bar. See No. 6. At one time, the right, at another, the left leg is lowered. When this exercise is performed at the extremity of the bar, as in No. 6, a great deal depends upon the steady position of the body. It is necessary that the teacher should stand close by the learner, in order to assist him in case of his falling. - 9. It is not difficult, when standing upon that part of the bar where the wavering is slight, to raise, by aid of the hands, one foot so high, (lowering the head at the same time,) as to be enabled to kiss the toe, as shewn in No. 7. When the learner is expert in this, let him attempt it on the wavering end of the bar, where it is much more diſficult. The foot is placed upon the bar, in the direction of the latter. The learner waits until all wavering has ceased; he then raises the foot slowly and steadily, and bends forward, taking great care all the while to preserve his balance. He seizes the foot quickly, but without making much motion, and conducts it to the mouth. Upon returning his foot to the bar, he should stand very steadily upon it. 10. Two learners meet upon the bar, and each endeavours to push the other off, by using one hand. See No. 8. The learners must recollect they are not to give a hard blow, but rather a push, keeping the arm stiff. This exercise teaches them to maintain their position upon a narrow round surface. 11. A support is placed under the end b, of the bar, and the iron peg which supports the latter in the stand d, is removed. All the learners then walk along the bar, at the distance of two paces behind each other. This exercise instructs the learners in crossing a river or ditch by means of a long pole. - - In walking along the bar, it is necessary to turn the feet outward, so as to keep them more across it than in its own direction. By observing this, the pupil is much less liable to slip. 2. As the upper surface of the bar is generally too smooth in very dry weather, the soles of the shoes should, in that case, be damped by rubbing them upon a wet spot of ground. 3. From the nature of these exercises, it is evident that they should never be performed with violence or rashness, but rather with patience and caution. If the bar swings too much, you should wait until it is steady, before you continue what you have begun. 4. The ground about the bar should consist of sand. 5. The teacher should always stand near the beginner to give him assistance. 6. No voluntary swinging of the bar, on the part of the learners, must be allowed. VIII. Climbing and Mounting. These arts are of the utmost importance to the military, maritime, and civil inhabitants of Britain. The soldier, who has been well taught in the gym- nastic school, has an immense advantage over both his com. rade and his enemy, in case of an attack upon a place difficult of access, such as the storming of a town, or the carrying of a commanding height. The sailor's life is spent in climbing, and he would always feel the benefit of early instruction in these practices. The traveller, afraid of danger or fatigue, passes rocks or mountains commanding the most beautiful prospects, which, if well instructed, he might ascend with ease and pleasure, and the inhabitant of the city would sleep more secure from the apprehension of fire, if he felt confident in being able at the shortest notice to descend the loftiest and most awkward elevations. Such security may be promised to him who has mastered the gymnastic art, as practised in vari- ous parts of Germany, and as now taught in England. - The Climbing-stand. This, with all its appurtenances, is represented in the Plate, fig. 5. It consists of two strong posts a and b firmly fixed in the ground; 20 feet high, and about 30 feet distant from each other. They support the beam c d, which is strongly fastened to them. The mast e, is fixed upright and very firmly in the ground, and in such a manner as to pass close by the beam cd, to which it may be attached by means of an iron band; though this is not necessary if it be supported by the slant post q on the other side of the stand. To the beam cd, are attached the implements for climbing; viz. two poles f and g, three ropes l, m, and n, a rope ladder i, and a mast h. The two standing-places o and p are intended for the exercises in mounting. A ladder leads to the lower one, and is made fast to the maste; another leads from the lower to the upper one. The firm construction of these standing- places must be executed under the eye of the teacher: the upper one p may be dispensed with if the latter thinks proper; it is merely intended for the purpose of strengthening the nerves of the learners by accustoming them to look down from a great height. - Climbing by means of both Arms and Legs. The teacher must require the learners to be expert in the exercises given in Section IV. pages 425 and 426, before they commence the following ones, to which they may be considered as preparatory. 1. Beginners ascend and descend the ladder which is fixed to the climbing-stand, in the customary way, until they acquire expertness and courage. - - 2. They descend with the back turned towards the ladder. “ 3. They mount and descend in the usual way, but only with one hand; and, after a little practice, carry something in the other. See No. 1. - 4. The learner goes up and down without using his hands. See No. 2. The ascent is extremely easy; after which he uses his hands in turning round so as to have his back towards the ladder when descending. In this part of the exercise, the teacher must always be ready to assist him. 5. Two learners meet upon the ladder, and wish to pass each other. They either both remain on the front part of the lad- der, and give way to each other as much as possible, or, if one of them is sufficiently expert in the two following exercises, he swings himself round to the back part, in order to let his com- panion pass. 6. The exercises now commence on the back part of the ladder. The learner easily ascends from step to step by advancing his hands and feet, at the same time, higher and higher. g The learner mounts along the front part of the ladder as usual; then swings himself round to the back part, along which he descends. - 8. The learner mounts and descends the ladder upon its back part, without making use of his feet. See No. 3. Al- though this exercise ought not, strictly speaking, to be in- troduced here, yet as we are busy with the ladder, there will be no harm in mentioning it now. It may be divided into two parts. The first consists in taking fast hold of the most convenient rundle with both hands, and raising the body forcibly upward. At this moment, one hand seizes the next highest rundle, and immediately afterwards, the other hand does the same. Both hands again raise the body as before, &c. In the second part of this exercise, the hands seize the rundles singly and alternately; which is much more difficult, and only accomplished by practised learners. . . - 9. climing in the Upright or stant Pole. The thickness G Y MI G Y M DICTIONARY OF MECHANICAL SCIENCE. of the upright pole f, is from two to two inches and a half, or more, according to the size of the learners. fectly smooth, and void of splinters. Its upper end is fastened by an iron ring to the beam cd. The slant pole g must be at least three inches thick. Neither of them is made very fast in the ground, but only sunk a little into it, in order that they may be easily replaced by poles of different sizes. The posi- tion of the climber is the same in both the upright and oblique pole, and is shewn upon the latter, in No. 4. touch the pole besides the feet, legs, knees, and hands. The climber, while he raises himself with both hands, draws his legs up the pole, as in fig. 4, then holds fast by them, and again places his hands higher up. He continues this alternate use of the legs and arms until he has reached the top. The descent is not at all diſficult; it is not performed similar to the ascent, but merely by sliding quickly down with the legs, without scarcely ever touching the pole with the hands, as shewn in No. 5. This exercise is more difficult upon the oblique pole, since the hands are more affected by the weight of the body. The learners should be made very perfect in this exercise, for every one ought at least to be sufficiently expert in-case of fire to slide himself down along a smooth pole placed against the window of a second or third story of a house. 10. Climbing the Mast is more difficult than the last exercise, for even when made of a moderate size, it cannot be spanned round by the hands. It is fixed quite firm in the ground; is from six to eight inches thick at the bottom, and thirty feet high. The learners must not be allowed to climb the mast until they are very expert at olimbing the poles mentioned in the last exercise, and are able to get from that, upon the beam c d. , All climbing succeeds best in hot weather, but more par. ticularly that of the mast. The position of the legs is the same as with the pole: boots are the best covering for the feet. Since the mast is too thick to be grasped by the hands, the climber must lay fast hold of his left arm with his right hand, and vice versá. Learners climb with much more ease and security, with naked arms, for the skin does not slip near so easily as the clothes. A climber up the mast adheres to it with his whole body, as in fig, 6, until he reaches the thinner part df it, as appears from No. 7. 11: Climbing the Rope-ladder. (See i, in the Plate.) The rope-ladder should have three or four wooden rundles to spread it out, and ought to be made so as not to twist round and en- tangle when used ; if it has this fault, it is unserviceable. It is much more difficult to mount the rope-ladder than the pole, the former hanging quite loose, and not at all fastened at the bottom. The muscles of the arms and hands are very much affected; for the latter must, when the learner is not sufficiently acquainted with this exercise, almost entirely sup- port the body, which continually inclines backward. The manner of proceeding in this exercise is easy, for it is similar to ascending a wooden ladder; but as the rope-ladder hangs perpendicularly, and is very flexible, the steps upon which the feet rest, are generally pushed forward by the unpractised, and the upper part of the body sinks out of the perpendicular position into a very oblique one ; whereby the whole weight of the body becomes supported by the hands, and the exercise is rendered so difficult that the learner cannot ascend very high. To obviate this, he must always have a fast hold of the two main ropes, as shewn in fig. 8, and keep the body, as much as possible, stretched out upon the ladder and upright. If the ladder is sufficiently strong, the teacher allows two or three of his pupils to get up and down at the same time; by which means they learn to pass each other. One hangs by a main rope until the other has passed him. - 12. Climbing either the Oblique or Level Rope. Let a rope be fastened from one post to another, or from the beam cd, to an adjoining post k, and in an oblique direction. Another might also be placed in a level. direction, having one end fastened at k, and the other to the post.b. In either case the learner fixes himself to the rope as in No. 9, in the position required in Exercise 7, Section IV. ; and advances along the rope in the way required in Exercise 9, Section IV. In this manner, a number of soldiers might cross a small river, with their arms and knapsacks, when other means failed. There are two ways of using the legs infthis excrcise; 1st, It must be per- Nothing must exactly as in Exercise 9, Section IV., so that the feet, either in ascending or descending, move forward along the rope alter- nately; or one leg only may hang over the rope, and be made to slide along it; but in both cases the pressure is painful, particularly if the climber does not wear boots. The 2d, which is the best method, is to place the sole of one foot, for instance, the right, flat upon the rope, and to lay the left leg across the instep of that foot; whereby the friction of the rope is re- moved. § 13. Climbing the Upright Rope. This exercise is shewn in the figure, upon two ropes l and m, because the securing of the rope by the feet may be done in two different ways. It is very easy to those who are already expert at climbing the upright pole. The only difficulty lies in seizing the rope with the feet so as to obtain a firm support. - The first method is shewn in No. 10, upon the rope l. Knees and thighs have nothing to do here ; only the feet are em- ployed. If the learner sit upon a chair, and cross his feet in the usual way, he will immediately perceive their proper posi- tion. The rope passes between them, and is held fast by press- ing them moderately together, while the hands alternately grasp higher up the rope. Hereupon the climber, hanging by his hands, also draws his feet higher up, fixes them again to the rope, and proceeds as before. - The second method, peculiar to sailors, is shewn at No. 11, on the rope m. The rope passes down from the hands of the climber, along one, generally the right, thigh, not far above the knee; winds round the inner side of this thigh, along the knee- hollow and the calf, and then across the instep of the right foot, whence it hangs loose. If the climber only treads moderately upon that part of the rope where it crosses the other foot, he will, by means of the varied pressure, obtain a firm support. The exercise depends almost entirely upon holding the right leg and foot so that the rope may retain-its proper winding, after being quitted by the left foot, when the hands have been raised for the purpose of drawing the body higher. This is easily acquired after a few trials. In descending, the hands must be lowered alternately, as they are raised in ascending, for if the hands slide down quickly, they will be injured. 14. Resting upon the Upright Rope. This exercise not only excites a lengthened power of the muscles, but also tends to, promote expertness in dangerous situations. It is represented in the figure, at No. 12, upon the rope n ; which must be much longer than what the height requires. The climber mounts to a moderate height, and then haults; swings the right foot three or four times round the rope, so that this winds round the leg; he then entwines it, by means of the left foot, once or twice round the right one, which he bends so as to point the toes upwards, and now treads the left foot firmly upon this last winding. The pressure which thus arises between the rope and the feet, opposes the whole weight of the body. In this position, he can rest a long time: but suppose he wishes to be still more at his ease; with this intention, he lowers his hands a little along the rope, as shewn in fig. 12, then holds fast with the right hand, stoops, and grasps with the left, that part of the rope which hangs below the feet. He raises himself again, and entwines this part a few times round his shoulders, hips, and the rope itself, until he is firmly entangled. 15. Climbing Trees. The preceding exercises have been applied to objects made very firm and secure by art, and were therefore, after good preparatory ones, attended without dan- ger. It is otherwise with trees: their branches frequently give a very insecure support; the nature of the wood must be considered ; consequently, this kind of climbing requires, with beginners, the careful attention of the teacher. The danger does not consist in clambering up the stem of the tree, but in climbing from one branch to another. Precautions. The teacher must only allow the learner to climb up low branches at first, so that he may narrowly observe his movements. He must stand by, and warn him from the branches which appear insecure, and make him acquainted with the important rule, to support himself almost entirely by the hands, and not to confide too much to the feet, since they easily slip from off the branches. Beginners must not be allowed to perform this exercise in winter, for then the withered branches are not so easily distinguished. G Y M G Y M DICTIONARY OF MECHANICAL SCIENCE. 429 The different advantages which must occur to the learner in this exercise, increase with his agility and courage. He is soon enabled to pass from the branches of a tree to those of an adjoining one, and so on along a whole row. If he have had sufficient practice with the rope, he will not always clam- ber up and down the stem of the tree, but seize a sufficiently strong branch, which hangs low enough to be reached from the ground with his hands, and swing himself either up to, or down from it. Should this branch be somewhat higher, he can make a preparatory run, and catch it immediately after having made a spring. - To render this exercise more agreeable, and to try, at the same time, the expertness of the learners, the teacher may sometimes take them to a group of trees; he then counts 15, and during his counting, each exerts himself to climb so high up a tree as to be without the reach of the teacher's stick; the endeavouring to escape which excites great laughter. Climbing by means of the Arms only. This is one of the best exercises for strengthening all the muscles of the chest, the arms, and hands; it is a true criterion by which to judge the powers of these members, and it also augments them most effectually. We seldom find a boy who is able, in his eighth or ninth year, to raise himself a little way either up the rope or pole by his hands only. The age of fourteen is generally the time when the arms become sufficiently strong ; therefore some attention must be paid to this point, with respect to the learners. The best preparatory exercises are the 5th and 10th in Section IV. The exercise itself may be applied to the ladder, (as already given in Exercise VIII.) to the pole, and the rope, either slanting or upright. J . Ex. 1. Climbing up the Pole by the Hands only, is perhaps easier than up the ladder, for with this the body hangs quite free, but with the former one side of the body is close to the pole, which facilitates the learner a little. See No. 13. When this exercise is applied to the upright pole, the position of the body will be good, if similar to that represented at fig. 13. The feet hang loosely, and remain perfectly steady. The climber must not be allowed to bend his knees, nor to stamp, as it were, in the air, nor to let the pole come between his thighs. There are two methods of employing the hands in this exer- cise. According to the first, which is the usual mode, both hands raise the body simultaneously; immediately after which, one quickly grasps the pole higher up, while the other supports the weight alone for a moment. The second, in which each hand alternately supports the body alone, and the other, quite free, seizes the pole higher up, in order to raise the body again, requires great practice and considerable strength in the arms. In climbing the slant pole, the position is similar to that in the 10th Exercise, in Section IV. - & 2. Climbing the Rope by the Hands only, should be first prac- tised upon the slant rope, as with it, the continual grasping higher up is much easier. The position of the hands and of the body similar to that required in climbing the pole. It should be observed, that of the preceding exercises, all those which require more strength and agility must not be kept up too long. Strength increases gradually, its growth is not only combined with exercise, but also with the develop- ment of the corporeal system. For this reason, such exercises should be frequent but not long. º Evercises in Mounting. These exercises require neither particular strength nor agility; they are intended to produce fearlessness, and the power of looking down from high stations, and consequently to prevent weakness of nerves and giddiness. The teacher will have little difficulty with boys accustomed to the country, but he must pay great attention to those who come from large cities, as they are frequently weak, nervous, and timid. If any one of them is sufficiently strengthened by the preceding climbing exercises, and becomes bolder in climb- ing the pole and the ladder, he may mount the first standing- place o. If he be very timid, then even his climbing to the top of the pole will be no certain proof of his having lost his timi- dity, for the firmness with which the climber clings to the pole, gives him a security which renders him fearless; he may still be afraid of standing quite freely upon the ladder or , the standing-place. Such a one must only ascend higher up the ladder gradually; turn round, and sit down upon a rundle, in 45. order to accustom himself to look down for a long time upon the ground. If he finally climbs the pole f. so as to place him- self in the riding position upon the beam cd, and can look down with indifference, he may then fearlessly get upon the lower standing-place. But whoever can ascend the beam from the pole, the rope, and the rope-ladder, and can shake the fane of the mast, (see No. 7,) may mount with confidence the upper standing-place p. - IX. Wrestling exercises both legs and arms, excites every muscle, strengthens the chest, circulates the blood, and gives youth courage, patience, and perseverance. It may be said to consist of heaving, fig. 4, pulling, fig. 8, and fighting upon the ground, on which the combatants used voluntarily to throw themselves down, as shewn in figures 2 and 3. This was the ancient mode, in which pinching, biting, scratching, and luxation, formed legitimate means of vanquishing an adver- sary. We have in modern wrestling altered these Grecian customs, where the virgins were taught to dance in public at certain festivals, to wrestle with each other, as in either or all the three groupes of wrestlers on the Plate, to run with the utmost speed over the adjoining country, to shoot with the bow, and to launch the javelin; and all these exercises they performed with scarcely any clothing to encumber them, and without any feeling of shame, for Lycurgus thought that where there was no concealment, there was no temptation. See Tuscul. Quaest. lib. 3, for Cicero's description of the pursuits of these daughters of liberty. - We proceed now to consider Gymnastics as tending to pre- serve or to re-establish health, by a development of the moral faculties and physical powers of man. 'This is the view which the politician and schoolmaster should take of this art, for the posture master can regulate the movements of the human body, and the Ourang-Outang has far more agility and pliancy of muscular power than man. But the study of gymnastics is inseparable also from that of medicine ; at any rate, the art of healing abandoned the temples, and took refuge in the aca- demies or schools; and although Captain Clias be not a phy- sician, he has given his work quite a medical turn, interesting, above all praise, from the edifice he rears, appropriating its parts to the wants of life, and to the laws of living econdmy. I speak from actual observation of this gentleman's instructipns to the young men at my own school. His constant study seems to be, to determine the most convenient methods for strengthening the powers of each organ, and to increase the energies of the vital properties. With this view, he has con- trived exercises peculiar to the action of each part of the body; and he begins at first by the most simple motions, to arrive progressively at the most complicated. In speaking of gymnastics, we are not here contending fo, these exercises as preservatives of health, but what is most important, as applicable in all the different kinds of dangerous and morbid disorders. And the injuries that appear capable of yielding to a well-combined and methodical movement of the lower extremities, are lumbago, sciatica, the imperfect anchiloses, sprains, a bad construction of the legs and thighs, palsies, stiffness, rheumatisms, gout, &c. These and other morbid affections ought wholly or in part to give way to a frequent exercise of the arms, when they have taken their direction towards the upper regions; but as the action of the muscles of the arms is almost always simultaneous with those of the thorax, the same exercises will naturally correct a num- ber of disorders and deformities with which the chest is threat. ened. Thus, obstimate coughs, recent asthma, tendency to a curved spine, and the vitious formation of the thorax, &c would find, in a great variety of these movements for the arms, an advantage that would be vainly sought for in the usual mode of treatment. So we are confident of the salutary effects resulting from the same practice on the visceras of the abdomen I have seen about 200 different exercises performed agree ably to Captain Clias's directions, of which not one could be classed among the games and pastimes of Scotland and Eng- land. And the great merit of these exercises appears to me to be, that, while the end of each is to increase the elasticity of the articulation, (i.e. the joints,) to favour the development of the muscular powers, to strengthen the body, and facilitate standing and moving in any attitude, without losing the equili- 5 R 430 G Y M G. ºf M DictionARY of MechAnical science. brium,-they teach youth also to brave and avoid dangers, and te overcome obstacles, which, to others, would be insur- mountable. . - I. The following is a sketch of the exercises applicable by Captain Clias to the lower extremities. - I. Walking, running, jumping, which he divides into walk- ing in general, preparatory movements, and the following exercises: - 1. The ordinary step. 2. Changes in place. 3. The double step. - | 4. The triple step. 9. The broken step. 5. Oblique and cross step. | 10. The ticktack. - It is easy to perceive how much these exercises contribute to develope the force, the suppleness, and, the agility of the lower extremities; as the hip, the knee, the muscles of the thigh, which make the movement, are the parts most fatigued. 2. Balancing on the feet may be considered introductory to dancing, and its exercises are ten : 1. Balancing on one leg. | 6. The cross touch. 2. The school step. | 7. The touch of the toe. 3. The pace of three times. 8. The touch of the heel. 4. First balance. - 9. Changing the guard. 5. To touch the ground. | 10. Walk near the ground. 3. Running, which, from preparatory movements, carries the pupil through ten exercises : 1. Running in place. 2. Rising and crouching. 3. Running in a square. 4. Spiral running. 9. Prompt running. 5. Sinuous running. 10. Precipitate running. Captain Barclay's walking 180 miles without resting, and still more, his doing 1000 miles in 1000 successive hours, afford strong proofs of what may be effected by persevering exercise; and are unparalleled to any exercise of the kind of which foreigners can boast. - - 4. Jumping in general, embraces * 1. Preparatory movements. 6. Galloping pace in place. 2. Rising & touching behind. 7. Simple jumping in place. 3. Trampling on the ground. 8. Redoubled jumping. 4. Walking pace in place. 9. Continued jump. 5. Trotting pace in place. 10. The spectre’s march. If the volume, strength, and suppleness of the members are increased, by means of exercises, there are none more proper for developing the lower extremities than these four sections. The details of these exercises occupy 60 pages of the original work before me; and a judicious gymnasian would, without doubt, vary and modify them in a thousand circumstances, of which he only can be the judge. II. The exercises of the superior extremities upon the plan of Captain Clias, embrace - 1. The Movement of the Arms, consisting of these exercises: 1. Raising them straight in front, parallel to the ears. 2. The oscillatory. or pendulum movement. 3. The circular, vertical, and superior movement. 4. Developing before, striking behind, and detaching sideways. 5. Swimming motions—the thrust—circling—hovering—point- ing to the ground. - m 2. Complicated Movements of the Arms and Feet together, in place or moving forwards and backwards, may be executed by persons of all ages, and in every station of life; for by their quick and rapid action, of short duration, but frequently re- peated, they are calculated to give strength alike to the youth and the adult, by making them active and pliant in their limbs, enabling the grown man to maintain an equilibrium between the body and mind, and the old man to warm his vital powers, which are perhaps nearly extinguished. The third chapter of the work of Captain Clias, treats of complicated exercises in a series of twelve different ways of climbing, wrestling, swimming, and vaulting. We arrive at wrestling, according to this system, by a course of preparatory exercises that serve as its introduction: as, - 1. Kissing the ground in equilibrium, on the arms and the points of the feet. - 6. The French step. 7. Walking on the heels. 8. Kicking. 6. Doubling the line. 7. Running with a stick. 8. Running moderately. 2. To the ground backwards, by supporting the body on the hands and heels. - - * . The seven or square. . The goat’s jump. * . . Squaring with the hands, or wrestling with the fists. . Head to head. - - . Binding. t . Bending upwards. . Wrestling with sticks. 10. Forming the lever. 11. The snares, or the trip. 12. Taking the advantage. 13. The first fall. - 14. Wrestling on the ground. - We forbear the description of each of these exercises, and observe that they are all the natural pastimes of youth, which only require to be directed by a man capable of appreciating the different dispositions of his pupils, in order to match them conformably to their strength, agility, and courage. r - Jumping, running, and skipping in a hoop, developes itself b passing the hoop forward, in place; passing it behind; run- ning through the hoop ; making the half-passage sideways, in place; the entire passage, and the return or passing above, which are all simple, amusing, and healthful exercises for boys at school. • Jumping, running, and skipping with a chord, is a well-known i | exercise, which might be regulated to passing before or behind, in place ; passing before in running; skipping in place; sim- ple passing and crossing, in place ; three alternate jumps, simple, double, and crossing ; doubling right and crossed, and doubling the cross. But, in short, elementary exercises of the lower extremities may be varied every hour during the years of pupilage. Among the complicated exercises belonging to the lower extremities is skating, for which see SKATING. w Elementary vaulting and the parallel bars, are also reserved to WAULTING. The combination of all these exercises forms one of the most complete systems for developing the muscular and physical powers of man, that can be devised in a medical and political point of view. The articles skating, swimming, and vaulting, which we have reserved for their proper places, will disclose the whole of the Gymnastics of Captain Clias, and they will be accompanied with engravings illustrative of the exercises. We do not know that we can add any thing more pertinent on this subject, than the following remarks, which occurred in a periodical publication, which, though it considered the book of Captain Clias more circumstantial, perhaps, than was abso- lutely necessary, yet admitted that the subject was deserving of attention, in as much as the close confinement incidental to the pursuits (as well as dwellings) of men who live in populous cities, joined to the difficulty of finding convenient fields for air and exercise, soon tends to produce an indisposition to active amusements. The inhabitants of London took great pains \to correct this mischief, two centuries ago, by especially pro- moting all such games, and festivals, and diversions, as were calculated to carry their youth into the open air, and to induce habits of activity and bodily vigour. In fact, king James the First was himself a great promoter of Gymnastics, as may be amply seen in Strutt's Sports and Pastimes of the People of England; but then came Oliver Cromwell and his sour-faced, canting Puritans, who put an end to these rational amuse. ments. Let that pass, and turn we to the advantage of the course which Captain Clias has established, and which, too, has been fully admitted of late years in most considerable schools; where lads are stimulated, and even compelled, to run, leap, swim, and join in other vigorous and manly diversions; and although it may appear at first that these are matters to require merely encouragement rather than instruction, still any thing like a system not only always forms the best kind of encou- ragement, but produces results far more rapid and decisive than any desultory attention can do. Therefore, though we do not go the full length of Mr. Clias’s scheme—such as to per- ceive the convenience of teaching “young ladies” to swim, or quite understand what persons he proposes should become their instructors—it is worth considering whether the employ- G Y M G Y R. 431 Diction ARY OF MECHANICAL scre N CE. ing pa. of their leisure hours in the practice of vaulting, run- ning, jumping, and such vigorous and healthful movements, is not likely to do lads from fifteen to twenty years old more good than breaking lamps in the street—(the only “gymnastic” exercise at present in repute)—or making nuisances of them- selves (more than need must be) in the passages of minor thea- tres. The evolutions suggested seem, without exception, to be very simple, safe, and extremely well calculated to improve the various muscular actions of the body, particularly as regards lads who are intended for the army or navy. The habit of steady firm walking is of itself alone an important acquirement; running, jumping, and wrestling, are also taught, and the climbing of ropes and poles. Swimming, as regards London, could only be taught in particular places; but one of Mr. Clias’s hints on the subject—the advantage of practising constantly in a light jacket and trowsers—seems not only to be very just as regards the circumstance under which men are generally most peremptorily called upon to swim, but would go to facilitate bathing in many situations where it is now impossible. On the general question, there can be but one opinion as to the ad- vartage of using all exercise which tends to increase or develop the powers of the human frame. In fact, that which we call courage, nineteen times in twenty, lies merely in a man’s knowledge of, or confidence in, his own faculties, as the con- trary feeling as generally arises from a distrust or conscious- mess of the want of them. There can be no reason but this, why one man should feel quite at home with a sword in his hand, who finds great discomfort in boxing; or another fight a bull with all the pleasure in the world, who would not at all like to meet a Thames-street carman. In he same way, it is matter of common observation, the readiness with which those classes accustomed to violent labour always enter into per- sonal conflict, because, in point of fact, their daily occupation is a description of conflict; and so again we have cases every day of prize-fighters by profession, whose whole “fight” lies in a confidence in their own strength and skill; and who—fancy- ing themselves over-matched in the least point—are notoriously not men of resolution. The terms of these teachers of “gym- nastics” ought to be very reasonable, both to bring their in- struction within the reach of the middle orders, and because— boys being taught in large classes, which will be the best mode of teaching them—lessons may be given at a low rate, and the master still well remunerated. For the practice in itself, we are decidedly inclined to think it beneficial; and we are glad to see the Government institutions setting the example of giving it their support. GYMNETRUS, a genus of fishes, of the order of thoracici, of which the most remarkable species is, 1. Gymnetrus ascanii, a native of the northern seas, which precedes or accompanies the shoals of herrings, and is known by the title of king of the herrings. - - . . GYMNOPAEDIA, a kind of dance established by Lycur- gus, and in use among the Lacedemonians. It was performed during their sacrifices, by young persons, who appeared in a state of nudity, and, while dancing, sung a hymn in honour of Apolio. . GYMNOPODIA. Among the ancients this was a species of shoe, which discovered the naked feet. They were much worn by the Grecian women, who were very fond of them. GYMNOSOPHISTS, a class of Indian philosophers, of great fame in periods of remote antiquity. They were so denominated from their going barefoot. The name is a Greek compound, signifying a sophist who goes naked. Among their peculiarities, it is said, that, on becoming old and infirm, they threw, themselves on a pile of burning wood, to prevent the miseries of an advanced age. Of this sect was Calamus, who burned himself in the presence of Alexander the Great. GYMNOTUS, or ELECTRICAL Eel, is the name of a fish which possesses in itself the power of electricity, communicat- ing it with great effect to all conducting bodies that come within its influence. The length of this fish is from three to four or five feet; the head is short, and sprinkled with perfo- rated dots; the body blackish, with a number of small annu- lar bends or wrinkles; nostrils two on each side, the first large, tubular,' and elevated; the other small, and not raised above the skin; the teeth small ; tongue broad; and with the palate watery. - * GYNAECEUM. Among the ancients, this was the apart- ment of the women, in the interior of the house, where they kept themselves retired out of the sight of the men, and were employed in spinning. Under the Roman emperors there was a particular establishment of Gynaecea, being a kind of manu- factories chiefly under the management of women, for the making of clothes and furniture for the emperor's household. In imitation of these, many modern manufactories, particularly those of silk, where a number of females are associated, are called Gynaecea. & as 4 - GYNAECOCOSMI, Athenian magistrates, in ancient times, whose business it was to regulate the apparel of women, according to the rules of modesty and decency. GYNAECOCRACY, a form of government, in which females are eligible to the supreme command. This mode of govern- ment is applicable to England and Spain, but the French exult that their monarchy is not gynaecocratic. - GYPSIES, a wandering race of people, against whom there are several statutes, by which they are treated as rogues and vagabonds. - -- GYPSINE Stone, a name given by some writers to the gypsum or fossil substance, of which the powder called plaster of Paris, is made by calcination. In many parts of Arabia there are vast rocks of this stone. It resembles alabaster, but is softer, and more lax in texture. & GYPSINUM MeTAL.LUM. In the natural history of the ancients, this was a name used for the common lapis specularis, of which they frequently made windows, as we do of glass. By some it was called Cyprinum metallum, because often found in the island of Cyprus. . GYPSOCHI, a name given to artists who work in plaster. GYPSUM, Sulphate of Lime. . Gypsum has probably been formed by the decomposition of iron pyrites, which supplied the sulphuric acid that afterwards united with the subjacent lime. As a confirmation of this, it may be observed; that the marl and sand over gypsum, in many parts of England, con- tain a large quantity of red oxide of iron. Gypsum is distin- guished from lime by its softness; it does not effervesce with any acid, being already saturated with the sulphuric. In some instances native sulphur is found intermixed with gypsum ; in these cases, probably the sulphuric acid has been decomposed by the presence of animal or vegetable matter during the decomposition of pyrites. Gypsum has been occasionally dis- covered in primary and transition mountains: it belongs more peculiarly to secondary stratified rocks, but may be formed in all situatious where lime and sulphuric acid exist near to each other. Though gypsum rarely contains shells, bones are some- times found in it; hence it has been supposed, that sulphuric acid destroyed the traces of organization in the former, which consist of lime and carbonic acid, but acted with less force on bones, which contain phosphoric acid. - GYRATION, CENTRE of, in Mechanics. When any system of bodies is caused to revolve round a centre, by the action of a force applied at a given distance, which remains unchanged, there will exist some point, in which, if all the matter be col- lected, the same force applied at the same distance will gene- rate the same angular velocity in the same time, as if the bodies were disposed at their respective distances: this point is called the centre of Gyration. - GYRFALCON, in Ornithology, is the name of a large and fierce species of falcon, called in English jerfalcon. GYRINUS, Water Flea, a genus of insects of the order coleoptera. The insects of this genus are found on the surface of waters, on which they run, and describe circles with a great degree of swiftness; when attempted to be taken, they plunge to the bottom, drawing after them a bubble very similar to a globule of quicksilver. Eleven species have been described, of which G. natator only is found in Europe. - GYROWAGI, a name given to a tribe of vagabond monks, who leaving their monasteries, under pretence of piety, wan- dered about from one religious house to another. The same appellation was also given to priests who left their parishes. . ... DictionARY of MECHANICAL SCIENCE. H A I H or h, the eighth letter and sixth consonant in our alphabet; though some grammarians will have it to be only an aspiration or breathing, pronounced by a strong expiration of the breath between the lips, closing, as it were, by a gentle motion of the lower jaw to the upper, and the tongue nearly approaching the alate. - &=ºgº - p H, used as a numeral, denotes 200; and with a dash over it, H, 200,000. - + HABEAS CoR PUs, in Law, a writ of various uses, and of different importance. The most efficacious kind in all manner of illegal confinement, is that of habeas corpus ad subjiciendum, which is the subject's writ of right, in cases where he is aggrieved by illegal imprisonment, or any unwarrantable exer- cise of power. By the statute of 31 Charles II. c. 2. emphatically termed the habeas act, it is enacted, That on complaint, in writing, by or on behalf of any person committed and charged with any crime, (unless committed for felony or treason ex- pressed in the warrant, or as accessary, or on suspicion of being accessary before the fact to any petit treason or felony plainly expressed in the warrant, or unless he be convicted or charged in execution by legal process,) the lord chancellor, or any other of the twelve judges in vacation, upon viewing a copy of the warrant, or affidavit that the copy is denied, shall (unless the party have neglected for two terms to apply to any court for his enlargement) award an habeas corpus for such prisoner, returnable immediately before himself or any other of the judges, and upon return made, shall discharge the party, if bailable, upon giving security to appear, and answer to the accusation preferred against him, in the proper court of judica- ture. That such writs shall be indorsed, as granted in pursuance to the act, and signed by the person awarding them. That the writ shall be returned, and the prisoner brought up within a Himited time, according to the distance, not exceeding in any case 20 days. That the officers and keepers neglecting to make due returns, or not delivering to the prisoner or his agent, within six hours after demand, a copy of the warrant of commitment, or shifting the custody of a prisoner from one to another, without sufficient reason or authority, (specified in the act,) shall, for the first offence, forfeit £100, and for the second offence £200, to the party aggrieved, and be disabled to hold his office. That no person, once delivered by habeas corpus, shall be recommitted for the same offence, on penalty of £500. That every person committing treason or felony, shall, if he require it, the first week of the next term, or the first day of the sessions of oyer and terminer, be indicted in that term or session, or else be admitted to bail, unless the king's witnesses cannot be produced at that time; and if acquitted, or if not indicted and tried in the second term or session, he shall be discharged from his imprisonment for such imputed offence ; but no person, after the assize shall open for the county in which he is detained, shall be removed by habeas corpus till after the assizes are ended, but shall be left to the justice of the judges of assize. That any such prisoner may move for and obtain his habeas corpus, as well out of the Chancery or Exchequer, as out of the King's Bench or Common Pleas; and the lord chancellor, or judges, denying the same on sight of the warrant, on oath that the same is refused, shall forfeit severally to the party aggrieved the sum of £500. That this writ of habeas corpus shall run into the counties palatine, cinque ports, and other privileged places, and the islands of Jersey, Guernsey, &c. That no inhabitants of England (ex- cept persons contracting, or convicts praying to be transported, or having committed some capital offence in the place to which they are sent) shall be sent prisoners to Scotland, Ireland, Jersey, Guernsey, or any place beyond the seas. The writ of habeas corpus issues out of the King's Bench or Common Pleas, not only in term, but in vacation, by a fiat from the chief justice, or any other judge; and runs into all parts of the king's dominions. If it issues in vacation, it is usually returnable before the judge himself who awarded it, and he proceeds by himself thereon, unless the term should intervene, when it may be returned in court. To obtain this writ, application must be made to the court by motion. This writ may also be obtained to remove every unjust restraint on personal freedom in private life, though imposed by a husband or a father; for when women or infants are brought up by habeas corpus, the court will set them free from an unmerited or unreasonable confinement, and will leave them at liberty to choose where they will go. The habeas corpus ad faciendum et recipiendum issues only in civil cases, and lies where a person is sued, and in gaol, in some inferior jurisdiction, and is willing to have the cause determined in some superior court; in this case the body is to be removed by habeas corpus, but the proceedings must be removed by certiorari. * Habeas corpus ad respondendum, is where a man hath a cause of action against one who is confined by the process of some inferior court: in which case, that writ is granted to remove the prisoner to answer this new action in the court above. - Habeas corpus ad deliberandum et recipiendum, is a writ which lies to remove a person to the proper place or county where he committed some criminal offence. Habeas corpus ad satisfaciendum lies after a judgment, when the party wishes to bring up a prisoner to charge him in exe- cution in the inferior court. Habeas corpus upon a cepi lies where the party is taken in execution in the court below. Habeas corpus ad testificandum lies to remove a person in confinement, in order to give his testimony in a cause de- pending. HABIT, in Philosophy, an aptitude or disposition either of mind or body, acquired by a frequent repetition of the same act. HACKLE, an implement used in dressing flax. - H/EMANTHUS, in Botany, blood flower. - HAEMATOPUS, the Oyster Catcher, a genus of birds of the order grallae, sixteen inches in length, and about the size of a crow, is to be met with on almost every sea-shore. The gene- ral food of these birds consists of shell-fish ; they force the limpet from the rock, and on perceiving the slightest aperture of its shells by an oyster, they insert their bills in it with admirable dexterity, and tear the tenant from his mansion. HAEMATOXYLUM, logwood. HAEMATITES, blood-stone. HAEMORRHAGE, a flux of blood from any part of the body. HAEMORRHAGY, in Medicine, a flux of blood. HAGIOGRAPHA, (Agios, Holy.) The Jews divide the Old Testament into three parts. 1. The Law, which comprehends the five books of Moses; 2. The Prophets; and, 3. The Writ- ings, termed by them Cetubim, and by the Greeks Hagiographa, whence the word has been introduced into the English language. The Cetubim comprehended the books of Psalms, Proverbs, Job, Daniel, Ezra, Nehemiah, Chronicles, Ruth, Lamentations, Ecclesiastes, and Esther. The Hagiographa were distinguished from the prophecies because the matter contained in them was not received by the way of prophecy, but simply by direction of the Spirit. . - : HAIL, or HAILstones, in Meteorology, an aqueous concre- tion of irregular form, descending from the atmosphere like frozen rain, a scourge that devastates and even annihilates in an hour the richest crops. , Hailstones are seldom spherical, as their size adds to their irregularity, and their cavities and angles indicate successive amalgamations. As hail falls mostly in summer, this would be a matter of surprise, did we not know the cause. The first drops, formed in the high regions, by the influence of greater cold, are almost immediately frozen. In falling, they traverse humid layers, whose vapours, suddenly condensed by the contact of a frozen body, cluster round it in | concentric coats, and form a mass, increasing with the interval passed. H A L. H A L. 433 DICTIONARY OF MECHANICAL SCIENCE. HAILING, the salutation or accosting of a ship at a dis- tance, which is usually performed with a speaking trumpet; the first expression is ‘hoa, the ship ahoay,’ to which she answers “holloa;’ then follow the requisite questions and replies, &c. g HAIR, slender filaments issuing out of the pores of the skins of animals, and serving most of them as a covering, but some animals in lieu of hair are covered with feathers, wool, and scales. All hair appears round, yet the microscope discovers square, triangular, and hexagonal hairs. And though, hair usually appears on the external surface of the bodies of ani- mals, there are many testimonies corroborating the fact, that, the tongue, the heart, the kidneys, &c. have in different indi- viduals been covered with hair. Human hair makes a very considerable article in commerce, especially since perukes have been so generally used. The hair of the growth of the northern countries is valued much beyond that of the more southern ones. The merit of good hair consists in its being well fed, and neither too coarse nor too slender. Its length should be about twenty-five inches. Hair is bleached on the grass like linen, after first washing it out in a bleaching water, and may be dyed of any colour. When it does not curl or buckle naturally, it is brought to it by art, first boiling, and then baking it. Hair is also used in various other arts and manufactures ; and when spread and left to putrify on corn lands, proves good manure. By an experiment of Berthollet's, 1152 parts of hair yielded carbonate of ammonia, 90; water, 179; oil, 288; gases, 271; coal, 324 parts. ($ tº From numerous experiments, M. Vauquelin infers, that black hair is formed of nine different substances, namely, 1. An animal matter, which constitutes the greater part. 2. A white concrete oil in small quantity. 3. Another oil of a gray- ish green colour, more abundant than the former. 4. Iron, the state of which in the hair is uncertain: - oxide of manganese. 6. Phosphate of lime. 7. Carbonate of lime in very small quantity. , 8. Silex, in a conspicuous quan- tity. 9. Lastly, a considerable quantity of sulphur. The same experiments shew, that red hair differs from black only in con- taining a red oil instead of a blackish green, oil; and that white hair differs from both these only in the oil being nearly colourless, and in containing phosphate of magnesia, which is not found in them. e tº e Hair is usually distinguished into various kinds: the stiffest and strongest is called bristles, such as that on the backs of swine. When remarkably soft and pliable, it is denominated wool, as that on sheep, and the finest of all is called down. HAIR, or Down of Plants, a general term, expressive of all the hairy and glandular appearances on the surface of plants, to which they are supposed by naturalists to serve the double purpose of defensive weapons and vessels of secretion. HAIR's Breadth, a measure of length, being the 48th part of inch. - • *"ºp, in Ichthyology, the English name of the Gadus, with two fins on the back, and the under jaw longest. It grows above two feet in length, but is the slenderest of all the gadi. See GADUs, the Cod, p. 346. ... HALBARD, or HALBERT, in the art of war, a well-known weapon carried by the sergeants of foot, is a sort of spear, the shaft of which is about six feet long. Its. head is armed with a steel point, edged on both sides, but besides this sharp point, which is in a line with the shaft, there is a cross piece of steel, flat and pointed at both ends, but generally with a cutting-edge at one extremity, and a bent sharp point at the other, so that it serves equally to cut down or push withal. - HALE, in the sea language, signifies pull. . HALF MARK, a noble, or six shillings and eightpence. HALF Moon, in Fortification, an outwork composed of two faces, forming a salient angle, whose gorge is in form of a half- - I1. * , "#LF-Pike, a defensive weapon, composed of an iron spike, fixed on an ashen staff; its use is to repel the assault of boarders in a manner similar to the defence of the charged bayonet among infantry; hence, it is frequently, termed a Boarding-Pike; it takes the epithet of half, from its having a much shorter staff than the whole pike. fine house or palace. 5. A few particles of. HALIOTIS, in Natural History, the ear-shell. Animal a |imax; shell univalve, dilated, ear-shaped, with a longitudinal row of orifices along the surface; spire lateral, and almost concealed. There are nineteen species. - HALLEY, EDMOND, an eminent English mathematician and astronomer, was born in London, October 29, 1656; to whom the sciences are much indebted for many important improve. ments and discoveries. HALL, in Architecture, a large room at the entrance of a The hall is properly the finest as well as the first of a suite of apartments. In halls, or saloons, ministers of state despatch business, give audience, &c. The length of a hall should be at least twice and one-fourth its breadth, and in height two-thirds the breadth. HALLIARDS, the ropes or tackles usually employed to hoist or lower any sail upon its respective masts or stay, except the cross-jack and sprit-sail-yard, which are always flung; but in small craft the sprit-sail-yard has halliards. HALO, is an extensive luminous ring, including a circular area, in the centre of which the sun or moon appears; whose light, passing through an intervening cloud, gives rise to the phenomenon. Those about the moon are most common. The following enumeration will perhaps be more acceptable to our readers than if we treated of lunar haloes only. Corona. When the sun or moon is seen through a thin cloud, a portion of the cloud, round the sun or moon, appears lighter than the rest; and this luminous disc is called a corona. They are of various sizes, but they seldom exceed 100 in diameter: they are generally faintly coloured at their edges. Frequently when a halo encircles the moon, a corona sur- rounds it. Parhelia, or mock suns, vary considerably in general appear- ance: sometimes the sun is encircled by a large halo, in the circumference of which the mock suns usually appear, which have often small haloes round them. The paraselene, the parhelion, and the several kinds of hale and corona, have all been considered as resulting from the intervention of clouds between the spectator and the sun or moon, through which the light passes. But we must be more philosophical. It is well known that the immediate effect of the different refrangibility of light, in producing colours, is sometimes spontaneously exhibited in the atmospherical phe- nomena of haloes, parhelia, and paraselenae; the edge nearest the luminary being generally reddish, and the remoter parts green and blue, without any well marked limitation of the different tints. These appearances must therefore be referred to the refraction of the prismatic crystals of snow, floating in, and descending through the atmosphere, in all possible, but especially vertical or horizontal positions, and sometimes, perhaps, from their connexion with other crystals, making angles of 600 with these positions. At Dantzic, in 1660, Hevelius saw two fine paraselenae: the first, March 30. At about one o'clock in the morning, the moon - A was surrounded by an entire whitish circle, B C D E, 45° in diameter, in which were two mock- at each side of the moon, of various colours, and emit- ting long whitish beams. . The tail of that on the left, ex- tended towards the thigh of Serpen- tarius; of that on the right, towards Jupiter 21. After- wards, at two o'clock, a larger circle, of 90°, diameter, sur- rounded the less one, and reached to the horizon. The tops of both these circles were touched by coloured arches, resem- bling inverted rainbows. The interior arch at C was a por- tion of a larger circle of 909; and the superior F a portion of a lesser, of 45°. This extraordinary appearance continued three South moons at B D, one . . 5 S - 4:34 H A L H. A. M. D1CTIONARY OF MECHANICAL SCIENCE. hours; the outward great circle vanished first; then the larger inverted arch at C, soon afterwards the lesser; and, last of all, the inner circle B C D E. - The second was seen on December 17, and on the first day after the full moon, at 30' past six in the morning, the moon being 120 high, she appeared with three mock-moons about her. The air being very clear, the moon first appeared, sur- rounded with a double corona, near her body, tinged with very bright and beautiful colours. On each side were two arches, of a circle about 45° diameter, extending down to the horizon, and coloured like the rainbow; in which were two mock- moons, with long white tails; that on the left was near Tºrocyon, with a shorter tail ; the other was longer. In - the upper part, where these collateral arches concurred, was another arch, inverted, and variously coloured; in the middle of which was a third mock-moon, duller than the others. A very extraordinary part of this appearance was a large, white, rectangular cross, through the moon's disk, whose lower part reached down to the horizon, but on each side did not quite touch the corona. It was so very bright and strong, that it shone distinctly and clearly till sun-rise; but the mock-moons disappeared a little before. º During the time that the Hecla and Griper were frozen up in the North Polar ocean, several interesting meteorological phenomena were witnessed. At ten A. M. Jan. 1st, 1820, a halo, whose radius was 22° 30', with three paraselenae, which were very luminous, but not tinged with the prismatic colours, was seen about the moon; and on the following day the same phenomenon occurred, with the addition of a vertical stripe of white light proceed- ing from the upper and lower limbs of the moon, and form- ing, with a part of the hori- zontal circle seen before, the appearance of a cross, as shewn in the accompanying diagram. - •, There was also at times an arc of another circle touching the halo, which sometimes reached almost to the zenith, and changed the intensity of its light very frequently, not unlike the aurora borealis. On the 4th of March also, at half-past eleven A. M. a halo appeared round the sun, at the distance of 220 17 from it, con- sisting of a circle nearly complete, and strongly prismatic. Three parhelia or mock- suns were distinctly seen upon this circle ; the first being directly over the Sun, and one on each side of it, and its own altitude, as in the preceding dia- gram. The prismatic tints were much more brilliant in the parhelia than in any other part of the circle; but red, yellow, and blue, were the colours which could be traced, the first of these being invariably - next the Sun, in all the phenomena of this kind that came - sº º --~~: - --- & Sait(it I North Florizoit, 'Weyl, af under observation. From the sun itself several pencils of: rays of white light, continuous but not very brilliant, extended in various directions beyond the halo, and these rays were brighter after they had passed through the circle, than they were in the part within it. This phenomenon continued nearly twº hours. The aurora borealis was seen faintly near the SSW horizon, for three or four hours before midnight. . On the 8th of the same month, from ten to eleven A. M., a halo and three parhelia appeared about the sun, in every respect similar to those seen and described on the 4th. About one o'clock P. M., there being a fresh breeze from the north- ward, with some snow-drift, the parhelia re-appeared, being much more bright and prismatic than in the forenoon, and accompanied by the usual halo, which was nearly complete, and whose radius was measured 22° 30'. The parhelia a, a. in the foregoing figure, on each side of the sun, were at times so bright as to be painful to the eye in looking steadfastly at them. When they were brightest, the light was nearly white. HAMMER, a well-known tool used by mechanics, of which there are various sorts, but they all consist of an iron head fixed crosswise to a handle of wood. Among blacksmiths, there are the hand-hammer, the uphand sledge, the about sledge, which is swung over head with both aims, &c. º HAMMER, A PoweRFUL Forge. This hammer is intended to be wrought by one or more men, as occasion requires. It is well adapted to the forging of bricklayers’ trowels, rounding of ships' bolts, beating gold or tinfoil, planishing brass, copper, or, in short, for any work in which a large hammer is required upon a simple principle. The weight of the hammer is seventy pounds, yet one man will work it with the greatest ease and accuracy, and it performs the work of two or three men. The steel forged with it is kept in excellent temper; for as it does not require to be so often heated as in the common way of working, it preserves a high degree of elasticity and firm. I16SS, - - This forge hammer is represented in the following engraving. Fig. 1, A, a block of oak, in which the hammer acts. B, the wheel or nave, in which the hammer-handle C is fixed; also the chains which give motion to the hammer by the quadrant D. - EE, are the two levers which work the quadrant D. FF, are the two pedals on which the man who works the machine treads alternately, holding the levers EE in his hands. When he treads on the right pedal F, he lifts the hand-levers EE, which motion raises the hammer C ; when he treads on the left pedal, he presses on the same levers, which motion lets fall the hammer. - *=s tº i - R | l º §: - §§ º §§ º . ſº ºš iſſiº ińſmiſſ § | - § - • * * - º $º - a ||||||||||}|H|||||||ſ|º]|} G º- ºf *Erººrººrººzºº | #|| G, is a rack which moves perpendicularly, by the action of a strong wooden spring H, placed in a trough underneath the centre of the machine; the rack is kept close to the quadrant K, by a bridge a containing a small friction roller. I, an additional steel spring, fastened to the ceiling over the machine, in order to assist the wooden spring H, when fewer hands are at work. ! - K, is the quadrant contained in the centre of the oak block A, under the nave B, which assists in raising or depressing the hammer, by the alternate actions of the pedals FF. - L, is a lever fixed on the axis of the quadrant K, which, at the time it depresses the rack G, pulls upon the hammer- handle C, by the chain M, which adds to the power of the blow. | H A N H. A. N. 435 DICTIONARY OF MECHANICAL SCIENCE. ... NO, are the two side levers, to be worked by two men, when more power is required. - - PP, are other two pedals, on which a man treads alter- nately, to give motion to the hammer, having an upright rod 9. chain to each pedal; one rod is connected from the right pedal P, to the lever 0, which raises the hammer; the other rod, from the left pedal P, is connected to the handle of the ham- mer C ; when the man treads upon the left pedal P, he acts upon the hammer C, and, by lifting the lever Q with both hands at the same time, adds double power to the blow: Q, is a wooden spring or stop, which prevents the hammer from rising too high, and accelerates the fall. R, is a bridle, which supports the wooden spring Q. SS, are two iron standards, with holes in each, to raise or depress the said spring. T, is a wooden standard, to support one end of the wooden spring Q. V, is a tempered steel spring standard, to support the ham; mer while out of action; it also gives ease to the springs, and prevents the heat of the anvil from softening the face of the hammer. - U, is a solid block of oak, on which the anvil stands. W, the anvil, with a hollow dove-tail on the top, for the reception of different faces, as the various kinds of work may require. ' º - X, a steel face, dove-tailed in the anvil. * Y, a steel spring, which lies beneath the hammer-handle, but only touches it when the hammer falls; this spring, when the heated metal is laid upon the anvil, and in a soft state, pre- It gives a recoil to the hammer, and permits the workman to modify or shorten the stroke of the hammer with quickness, vents the hammer from falling upon it with its full force. ease, and regularity. Z, a weight hung on the arm of the quadrant K, in order to counteract the power of the hammer occasionally, when light work is to be forged. The hammer head with the face let into it may be taken out and changed, to suit different kinds of work. - HAMMOCK, a piece of hempen cloth, six feet long and three feet wide, gathered together at the two ends by means of a clue, and hung horizontally under the deck, forming a recep- tacle for a bed. There are usually from fourteen to twenty inches in breadth allowed between decks for every hammock in a ship of war; this space, however, must, in some measure, depend on the number of the crew, &c. in proportion to the room of the vessel. In preparing for battle, the hammocks, together with their contents, are all firmly corded, taken upon deck, and fixed in various mettings, so as to form a barricade against small shot. See the article ENGAGEMENT. ... HANAPER, an office in Chancery, under the direction of a master, whose deputy and clerks answer, in some measure, to the fiscal among the Romans. The clerk of the hanaper receives all fines due to the king for seals of charters, patents, commis- sions, and writs. He attends also the keeper of the seal daily, in term, and at all times of sealing, and takes into his custody all sealed charters, patents, &c. - HANCHES, in Architecture, are intermediate parts of arches between the crown and the spring at the bottom, being probably about one-third of the arch, and placed nearer the bottom than the top. Hanches are likewise called spandrells. HAND, a measure of four inches, or of the clenched fist. In Painting and Sculpture, it signifies also the style of the artist. —Hands are borne in coats of armour, right and left, expanded or open; and a bloody hand in the centre of an escutcheon, is the badge of a baronet of Great Britain. HAND BREADta, a measure of three inclies. HAND Cuffs, an instrument formed of two circular pieces of iron, each fixed on a hinge on the ends of a very short iron bar, which being locked over the wrists of a malefactor, prevents his using his hands. HANDMILLS, are commonly used for some culinary pur- poses, as the grinding of coffee, pepper, and the like. Some- times handmills of larger size are used to grind malt, wheat, &c. and in such cases the hand is generally applied to a winch handle; but the effort of a man may be applied to a lever mov- ing to and fro horizontally, nearly as in the action of rowing ; and this is a very advantageous method of applying human strength, the effort being greatly assisted by the heaviness of the man in leaning back: we shall therefore give a brief de- scription of this kind of mill, which is represented in the follow- ing figure. The vertical shaft E G carries a toothed wheel C, and a solid wheel F ; the latter being intended to operate as a regulating fly. Upon the crank A B hangs one end of an iron bar I, the other end of which hangs upon the lever H K ; the motion being pretty free at both ends of this bar I. One end :-ºº-ºº::=-----------Tº-T-Tº -*-m-mº- | E. | |& - s Iſº of the lever HK hangs upon the fixed hook K, about which as a centre of motion it turns. Then, while a man, by pulling at the lever HK, moves the extremity H from H to N, the bar I acting upon the crank A B, gives to the wheels C and F half a rotation ; and the momentum they have acquired will carry them on, the man at the lever suffering it to turn back from N to H, while the other half of the rotation of the wheels is com- pleted. In like manner another sufficient pull at the lever HK gives another rotation to the wheel C, and so on, at plea- sure. The wheel C turns by its teeth the trundle D, the spindle of which carries the upper millstone. In this mill, the nearer the end of the bar I upon the lever HK is to the fixed hook K, the easier, cateris paribus, will the man work the mill. If the number of teeth in the wheel C be six times the number of cogs in the trundle D, then the labourer, by making 10 pulls at the lever H in a minute, will give 60 revolutions to the upper millstone in the same space of time. HAND RAILING. Hand-railing is the art of forming hand- rails by moulds according to geometrical rules. The principles upon which this art depends, are that of cutting a right prism through any three given points in space, and that of forming a development of any portion of the surface of the prism. In order to illustrate this, let the interior surface of the sur- rounding wall be that of an entire cylinder, and let the breadth of the steps be divided into the frustums of equal and similar sectors, and let the heights be all equal, as is universally the case ; then, if an interior cylindric surface be erected concen- tric with the wall, and the ends of the steps or surfaces on which we tread, and the planes of the risers tending to the axis be supposed to meet the interior cylindric surface, it is evident that if the portion of the intercepted surface contained between the indented line formed by the ends of the steps, and the cir- cumferent line at the base, be developed or stretched out, all the points of the indented line formed by the outward or salient angles, will be in the same straight line, and all the points formed by the inward or re-entrant angles will be in another straight line. It is also evident, that this will not only be the case with cylinders, but with cylindroids, and every other description of prism; that is, the points of the development of the indented line will always have such a position, that two 436 H A N H A N DICTIONARY OF MECHANICAL SCIENCE, straight lines parallel to each other may be drawn through the whole number of points. - The points of concourse of the salient angles are called the nosings of the steps. - : The line drawn through all the nosings of the steps, is called the line of the nosings. - Now let the portion of the cylinder before uncovered, be again enveloped, the development in this state becomes an envelope, and the line of nosings becomes an uniform helix, which would be the form of the rail for such a stair. In this case it would be easy to execute the rail to any length we please, in equal portions succeeding each other; for as the curvature of the helical line is every where the same, the same moulds which are used in the formation of one piece, would serve for every succeeding piece. The steps placed around the circular part are termed wind- ers; in these the risers tend to the axis of the cylinder. Steps which have their treads the same breadth, are termed flyers; in these the risers are all parallel. . Very few staircases are however entirely circular, but those of the semi-circular form, with winders in the semi-circle, and flyers below and above, are very numerous; in such the line of nosings would be crooked, and would form an angle at the junction of the flyers and the winders, and that round the semi-circle would be a helix, consisting of half a revolution. • ‘ - In the development of the steps, the line of nosings would consist of three straight lines, the two straight lines through the nosings of the flyers would be parallel to each other, and each extremity of the middle one would join one extremity of each of the other two ; the angles are commonly taken away by introducing a curve in their places. A hand-rail, however, is not a mere helical line, but a solid, which may be contained between two concentric cylindric sur- faces, or concentric prismatic surfaces. The principles are the same, whatever be the form of the plan. A solid erected upon any plan, is called a prism ; a cylinder is therefore a round prism, and a cylindroid an elliptic prism. A hand-rail may stand upon a circular base, or partly circular and partly straight, or upon an entire elliptic base. In the construction of hand-rails, all prisms are excluded which consist of plain surfaces, or, which is the same thing, where the sides of the plan consist entirely of straight lines, as in such cases, the rails themselves are either straight, or partly curved and partly straight from the top and lower sides only, the sides being in vertical planes. We shall therefore confine ourselves to prisms that stand upon a circular base, or upon an elliptic base, or upon a base that is partly circular and partly straight, or, lastly, upon a base that is partly elliptical and partly straight. These two last may be said to have compounded bases or plans, and the former two simple bases or plans; let us call such a prism a curved prism. The plan of any curved prism is understood to be of the same breadth, and consequently the solid erected thereon will be every where of the same thickness. The prism may there- fore be a hollow cylinder, or a hollow cylindroid, or a concave body partly cylindric and partly straight; the latter may be open on one side, and may have the four planes which join the curved surfaces parallel to each other, and tangent to each of the cylindric surfaces. Let us therefore suppose such a prism as that last mentioned, and let us suppose it to be cut entirely through its vertical surfaces, in such a manner that any point in the surface of division may coincide with a straight line every where perpen- dicular to the external prismatic surface, then, every such line will be parallel to the plane of its base, and those lines in the cylindrical part of the prism will tend to the axis. Now it is evident, that the cut or dividing surface will not be a plane, but will wind or twist between the cylindric surfaces. It is also evident, that the cut may pass through a line drawn in any manner we please, in one of the prismatic surfaces; or, that the development of this line may have any degree of curvature in the whole length, or in any portion of the length, or may even be a straight line. One of those being supposed to be the case, let the upper part of the prism be taken away, then the upper surface of its remaining part will be brought to view; let a line be drawn on the exterior surface, parallel to the arris, and another on the concave side, parallel to its arris; and let another cut or dividing surface be made to pass through the two lines thus drawn, and let the upper part be removed by this division, then the part thus removed will form a solid helix or kind of half screw, which may be either uni- form in its upper and lower surfaces, or have any degree of curvature in any part that may be required, according to the development before mentioned. This is the form of the rail for such a stair, but to form the solid helix, without cutting it, from a hollow curved prism, is the thing required to be done in hand-railing. Now, seeing that two of its sides are actually cylindrical, and would be vertical if placed in position; and that the other two winding surfaces may be formed to any development we please; let us therefore take any determinate portion of the helical solid, as a quarter of a revolution, or perhaps something more, as occasion may require, and endeavour to form such a portion or wreath out of a thin plank, instead of cutting it from a solid curved prism. Before this can be done, it is necessary to understand the principle of cutting a prism through any three fixed points in space, by a plane passing through these points; the points may be in the surface of the prism itself, and may be either all in the concave side, or all in the convex side ; or partly in the concave side, and partly in the convex side:—That such a supposition is possible will readily appear, since any three points are always in the same plane; and, therefore, the plane may cut the prism through any three given points. - The three points through which the section is cut, are said to be given, when the seats are given on the plane of the base of the prism, which plane is understood to be at right angles to the axis of the prism, and when the distance or heights from the seats to the points themselves are given. --> It is always to be understood, that the three seats are not in a straight line, and consequently the three points themselves not in a straight line. The seat of a point in space on any plane, is that point in the plane, where a perpendicular drawn through the point in space, cuts the plane. . This being established, we shall proceed to shew the best means of applying these principles to hand-raiſing. r In the helical solid, the winding surface connecting the tw prismatic surfaces, was defined to be of such a property, as to coincide with a straight line perpendicular to the exterior pris- matic surface, and consequently, if the axis of the curved prism be perpendicular to the horizon, every such line will be parallel to the base; now, let the seats of three such lines be given on the plan, viz. let each extreme boundary be one, and let another be taken in the convex side, passing through the point which would give the middle of the development of the said side of the plan; the three seats would be terminated by the convex and concave sides of the plan, and will always be perpendicular to the convex side, and equal in length to each other. Let us call the three level lines, of which their seats are given, the lines of support; let a plane be laid on the three lines of support, the plane will either rest upon three points or upon one of the said lines and two points ; it is evident that the points which come in contact with the plane, will be at one extremity of each line of support; let each of these points which come in contact with the plane thus posited, be called a resting point. The three resting points are the three points in space, through which the plane is supposed to pass, that cuts the curved prism. Now, because that each line of support has two extremities, there will be six extreme points in all, but as only three can be resting points, unless the plane coincides with one of the lines of support, it will be proper to shew, which three of the six are the resting points. Let the plane, thus laid upon some three extremities of the lines of support, be continued to inter- sect the base of the curved prism, then the nearest extremity of the seat of any line of support to the intersecting line, is the seat of the resting point of that line. For this purpose let a development of the convex side of the rail be made according to the plan and rise of the steps. -- ：） |- |- ： … |------ … ：-） ---- vaev v ºzay H A N H A N 437 , DICTIONARY OF MECHANICAL SCIENCE. The part of this development that is made to bend round the convex, or concave cylindric surface of the helical portion or wreath, is called a falling mould, which is supposed to be brought to an equal breadth throughout its length. Only one falling mould is used in the construction of hand-rails. Let, therefore; the falling mould for the convex side be constructed, and let two-straight lines be drawn from the ends of the upper edge of that part of the falling. mould corresponding to the ends of the wreath, perpendicular to the base of the whole development; also, let another intermediate line be drawn parallel to the other two, so as to bisect the part of the base intercepted by the said two parallels: the three parallels will thus give the heights of the three, resting points, the shortest height is at one extreme, and the longest at the other. Sup- pose now, the shortest of these three heights taken from each of the three, and the remainders taken at heights, instead of the whole, then the height of the first resting point will be nothing, and will therefore coincide with its seat; then, if the middle height be less than half the length of the remaining height, the seats of the resting points will be the first and second extre- mities of the first and second lines of support taken on the convex side, and the extremity of the third on the concave side. The first resting point is a point in the intersection of the plane of the base with the inclined plane. The process is now completely reduced to that of finding the section of a prism through three given points, which suppose to be done, and the plane of section will touch the supposed wreath, at the resting points of each line of support, without cutting the wreath of any such line—then, the three lines of support will be on the same side of the plane, viz. on the under side. Let us suppose now, another section taken below, and parallel to the former, so that the wreath may be just contained between these parallel sections, or planes; the, distance between the two sections will represent the thickness of the plank. - The section of the prism through its vertical surfaces, is called the rake, or the rake of the plan: and a mould being cut to the rake, is called the face-mould. - The above are the general principles; the particulars will be best understood by the explanations which accompany the diagrams in the Plate, and the following wood engravings. . Let fig. 1, No. 1, in the Plate, be the plan of a geometrical stair, with eight winders in the semi-circle, and flyers above and below; the first or lower steps being denotcd by the scroll a ; let glp m r be the plan of the part of the rail that is to be formed in two wreaths; and q l and m r straight parts; in order for the better securing of the wreaths to the straight parts opposite the flyers. Let fig. 1, No. 2, be the development of twelve steps, in- cluding that of eight winders, two flyers below and two above; D B being the base, and B C the height. In the base D B, No. 2, LPM is the development of l pm, No. 1, and L D, M B, the breadths of two steps corresponding to the plan. In the height B C, N O is the height of the winders, and N B, O C, each the height of two steps answering to the flyers at each end. DE FC, is the line of nosings; the parts DE, FC, of the ſlyers, being parallel to each other, and joined by the part EF, the development of the winders; G R H, and I S K are curves tanged by the straight lines E. D, EF, and FE, FC, at the points G, H, I, K, or rounded off, as shewn at No. 3, on a longer scale, so as to form an agreeable curved line without angles. #. line G. R. H IS K may be called the line of the rail, being of the same form as the line bisecting the breadth of the deve- lopment of the rail, for the one may be supposed to be every where of the same height from that of the other, and therefore, the line G R HIS K, may be conceived to be the development of the rail. No. 3 shews the manner of drawing the tanged curves G R H, and ISK; No. 2 the upper one IS K, being the same as the lower one G. R. H., but inverted. No. 2 shews more lines than are wanted in practice, in order to shew the connexion between the development of the steps, and the development of the line of the rail. But, as the deve- lopment of the line of the rail is all that is wanted, make a b, No. 4, equal to the height of the winders, draw a c and db, at tº right angles each with a 5: make a e and bf each equal to the development of lp or p m, No. 1; make ec, and fil, the breadth of a step; draw eg and d k parallel to ab; make c g and d k each equal to the height of a step; join eg f k and ef; make e h equal to e.g., and fi equal to fle, and draw the tanged curves 9 * h and is k as ‘before; then g : h is k, will be the line of the rail, as in No. 2; for ef will be obtained, equal to EF, No. 2; and e ly, will be the section of a flyer at the lower end, and fak the section of a flyer at the upper end. The breadth of the falling mould, in common cases, is about two inches, therefore, two lines being drawn parallel to the line of the rail, each at an inch distance from it, gives the complete falling mould for both wreaths. The two párts of the falling mould, as divided by a b, are equal and similar to each other, and would therefore coincide if applied together. . . ." Let fig. 2, No. 1, be an enlarged plan of the rail, of double dimensions to No. 1, fig. 1, in order that the moulds may be raore exactly obtained, and the construction more clearly seen. Let A B C D E FG, fig. 2, No. 3, be the plan of the part of the wreath to be formed, A G being the seat of the line of support at the lowest part, and DE that at the highest part: then A is the seat of the resting point of the lowest end, and E that at the highest end. Take the point C, between A and D, so that .C., in the development of the line A B C D, may divide the said development into two equal parts. º Let A B C D, fig. 2, No. 2, be the development of the curve A B C D, No. 3; the parts AB, BC, CD, being the respective developments of AB, BC, CD, No. 3. . In No. 2, draw D K perpendicular to D B ; and make D K equal to the height of eight steps; draw KS parallel and equal to D B; join BS ; produce K S to T, and D B to V ; make ST and B V each equal to the breadth of a step; draw. TU and WW parallel to D K; make TU and VW equal to the height of a step; join W B, BS, SU: then W B SU is the line of nosings. The whole is completed as in No. 3, fig. 1. Draw A X parallel to KD, cutting the upper side of the falling mould at X; draw XZ parallel to A D ; produce KD to Z, and let K D cut the top of the rail at I; through C draw Y J, parallel to D K, cutting the top of the rail at J, and XZ at Y; then Y J and Z I, re- spectively, are the height of the resting points, whose seats are C and E, No. 3. In No. 2, draw J R parallel to B D, cutting DK at R. In No. 3, join the seats E and C of the resting points, and produce E C to L. In J R, No. 2, find the point O, by making R O equal to EC, No. 3; join I O, and produce I O to meet X Z at Q. In No. 3, make E L equal to Z Q, No. 2, and join A L; through G draw H K, perpen- dicular to A L, and produce L.A. to H ; through E draw Ei parallel to L. H., cutting H K at I; make Ii equal to Z I, No. 2, and join H i, and produce Hi to k. To find any point in the curve of the section, take any point M in the boundary of the plan, and draw Mp parallel to E i, cutting Hi at p and H I at P; draw p m at right angles to Hi, and make p m equal to PM, and m is a point in the boundary of the rake. In like manner, let M P cut the concave side of the plan at N ; in p m take p n equal to PN, and n is a point in the concave side. A sufficient number of points being thus found, draw a mixed line, a b c defg, through the whole, and a b c defg is the figure of the rake. For greater accuracy and despatch, it will be necessary to find a point in the rake corresponding to the extremity of every straight line in the plan, as shewn by small letters of the same names as the capitals on the plan. The part A B F G being a parallelogram on the plan; the cor- responding part a bfg, on the section, is also a parallelogram; in this case it will be only necessary to find the points a, g, f. Join a g and gf; draw a b parallel to gf, and fib parallel to ga, and the point b gives the commencement of the convex curve b c d, and the point f that of the concave curve. It remains to be shewn that H L, No. 3, is the intersection of the plane on which the section of the prism is formed ; for the point A is not only the seat of the lowest resting point, but the resting point itself. A is therefore the point in the intersection of the cutting plane. In No. 2, draw. O A parallel to KZ, cutting BZ at A ; conceive the triangle IQ Z to be removed to No. 3, so that the point Z may be upon E.; and because R.O A.Z is a parallelogram, A Z is equal to RO, and R. Q is equal to E-G by construction; therefore,the point A will iall upon. C.; and 5 T & *~, 438 H A N HI A N DICTIONARY of MechANICAL science. by construction, the point Q will fall upon L. Conceive the triangle, with its base, thus coincident with L E, to be raised perpendicularly to the plan; I will be the resting point over E, and O: the resting point over C.; therefore the points I and E will be in the plane of section, and consequently be the straight line IO Q; but the point Q, now supposed to be coin- cident with L, is common. to the plane of the base; and the plane of section, Q, is therefore a point in the intersection of the cutting plane and the base. The point A has likewise been , shewn to be a point in the intersection; therefore the straight line HL, passing through the points A and L, is the intersection of the cutting plane with the plane of the base. The point L, No. 3, will be obtained also by a fourth propor- tional to I R, I Z, R O, or Z A, No. 1, setting it from E to L. A mould being cut to the form of the section, as here obtained, is called by workmen, the face mould, which we shall suppose now to be made. To find the Thickness of the Plank, out of which the Wreath is to be cut.—Let Z I, No. 2, cut the under edge of the falling mould at s, transfer Zs upon K k, No. 3, from K to 6; then the nearest distance between the point 3 and the straight line Hk, is the thickness of the stuff at the upper joint. The wreath, when formed into two prismatic surfaces, and into two winding surfaces, is said to be squared. This forma- tion is all that is required from geometrical principles. Then, supposing the wreath set in its proper position, every section made by a vertical plane, perpendicular to the convex side of the plan, will be a quadrilateral with its two vertical sides parallel, and at right angles to the upper side, and at oblique angles to the lower side. This arises from the top being so formed as to coincide in every part with the line perpendicular to the prismatic surface as defined, and the lower winding sur- face by gauging upon each cylindrical surface from the top. To draw the Rake on the Slides of the Plank, in order to plumb the two Sides of the Wreath.-Let A B C D, fig. 3, No. 1, be a development of three sides of plank; let A E, H D, be the top; E F, G H, the edge ; in breadth equal to the thickness of the stuff obtained from No. 3, and F B, C G, the under sides; let the lines E H and FG be parallel to k H, fig. 2, No. 3, in order to be more easily comprehended, (as otherwise, it is not neces- sary;) let a b c def, on the top of the plank, be the rake formed by the face-mould, the point g being in the line H E, and the line g e, making the same angle with g E as the line g e, fig. 2, No. 3, makes with g k, draw g K, making the angle H g K equal to the angle H k K, or Hi I, or Hp P, fig. 2, No. 3, cutting the arris, fig. 3, No. 1, GF, at K, then the same mould being drawn on the under side, with the point g at K, and the chord, e.g making the same angle with KF, that eg, on the upper side, makes with g E, or the distance of the point e from G F, on the lower side, equal to the distance of the point e from HE, on the upper side. Let us now suppose lines drawn in the above manner upon the three corresponding surfaces of the plank to that of the figure, and let the plank be cut out with a bow saw. In the act of cutting, the kerf must be kept close to the corre. sponding lines of each rake, and the line of the teeth of the saw parallel to g K, and when the piece of the wreath is entirely divested of the superfluous wood, the sides thus formed will be plumbed. To draw the Rake upon the Plank in every Position to the adjoining arris of the Edge.—Let fig. 3, No. 2, be a development of the plank as before, the same letters referring to the same parts. Let a be d e f g be the rake drawn by the face-mould, the point g being in the arris H E, and the chord g e forming any given angle with the arris H E, less than that formed in No. 1, fig. 3, by the chord ge, and the arris H. E.; find g as before from No. 3. In No. 3, draw g I, making the same angle with the pitch line g k, as g emakes with g E, in fig. 3, No. 2, draw g L perpendicular to H E, cutting the lower arris G F in L; make the angle KL g equal to the angle e g I, fig. 2, No. 3; make L g equal to LK ; through g draw M. N, parallel to G F ; then drawing the rake upon the lower side by the edge of the mould, so that the angle e g N, on the said lower side, may be equal to the corresponding angle e g E on the upper side; the two sides of the piece that is to form the wreath may be plumbed as before, so as to correspond with the plan when set to its position. If it is required to draw the rake with each extremity of the concave side of the mould in the arris of the plank as in fig. 3, No. 3, it is only making the angle KL g equal to the angle eg k, fig. 2, No. 3: the rest is drawn, and the plumb side is formed in the same manner as No. 1 and No. 2, fig. 3, which suppose to be done, bend the corresponding part of the falling mould, fig. 2, No. 2, round the convex side of the piece for the wreath ; bring the points X and J to the plane at the top, and draw the line of support at the upper extremity upon the end of the wreath; now, bring the upper end of the falling mould close to the extremity of the line of support, and draw a line by the upper edge of the falling mould ; cut away the super- fluous wood in the manner before described, and this will form the back or top of the rail; then gauge the two vertical sur- faces to the same breadth, and cut the superfluous wood away from the under side; this portion of the rail will then be squared. The wreath for the other portion above, is identi- cally of the same form ; therefore, if two pieces are prepared by the same moulds and levels, then supposing one of these wreathed pieces to be set in its position for the lower part, and let the upper part be set in the same position, and then inverted, so that the top and bottom ends, and the upper and lower winding surfaces, will have changed places, but each of the vertical surfaces kept still upon the same side; let the lower end of the higher piece be brought to contact with the higher end of the lower piece, that the two planes may coincide and form a joint; the helical solid for half a revolution will be formed out of a straight plank, as required to be done. The two wreathed portions of a hand-rail are not always alike, as in the preceding example; this may happen in diffe- rent ways, as from one quarter of the semicircular part being divided into winders, and the other undivided, or, from the rail being placed higher upon the winders than over the flyers; but in whatever way the variation takes place, the application of the principle is the same ; it only requires moulds to be constructed for every such variation, or separate part. The intricacy of the diagrams constructed upon the inven- tor's former principles, prevented their being generally under- stood, and very few could practise with success. But the principles here laid down, are so invariable in their result, so simple and expeditious in their application, and so easily to be comprehended, even by a moderate capacity, that they cannot fail of being introduced into general use. They unite the requi- site properties of saving labour and stuff, the workman con- structs his moulds with ease, and has less superfluous wood to remove. The edge of the plank is kept square, which entirely supersedes the bevelling, and is even in this point attended with a considerable saving of stuff and time, as it allows suffi- cient wood at the ends to make the heading joints, and as the piece which is cut out of the rail piece from the hollow side, may be turned into use ; but if the edge of the plank were bevelled, it would require to be much longer, in order to form the heading joints, and the piece cut out would be too trifling to be employed to any purpose. In addition to the advantages already enumerated, the work- man will be encouraged by the clearness of the different steps of the process, which cannot fail of fully satisfying his mind as to the final result. It is likewise a great accommodation, that any rail whatever may be cut out of the same thickness of plank, and that the mould may be applied in any direction which the workman pleases to the surface, in order to save wood or match the fibres at the joint. - The art of forming hand-rails round circular or elliptic well- holes, without the use of a cylinder, is entirely new. Price, the author of the “British Carpenter,” is the first person who seems to have had any idea of this art; the subse- quent writers following his schemes, which were very uncertain in their application, have added nothing to the subject, but have even thrown it into greater obscurity. The first successful method of squaring the wreath or twist, was invented and published in the “Carpenter's Guide,” in 1792; and certainly was the first wherein the process was sub- jected to any thing like geometrical principles, from which the result was attended with success. In the “Carpenter’s Guide,” (generally called simply “The Guide,”) the formation of the # H A N H A N 439 DICTIONARY OF MECHANICAL scIENCE. face-mould was regnlated by the falling mould or the deve- lopment of the rail, not by the rise and tread of the steps, as shewn by Price and his followers. When the back or upper surface of the rail had a considerable concavity, as in the case of junction of flyers and winders, the consequence of this regu- lation in many cases, in the formation of the rail, was the saving of seven or eight inches in the thickness of stuff; and thus, while the method laid down by Price required a plank from six to nine or ten inches in thickness, according to the degree of concavity; that in “the Guide” seldom required a plank more than three inches thick, excepting in small well-holes of three or four inches in diameter. - From the great thickness of stuff to cut through, and the quantity to be taken away, the time required to form the piece of wood into a wreath by Price’s method, must have been at least double to that in “the Guide,” and proportionally more so, as the thickness of the plank required by Price, was greater than that in “the Guide.” But though considerable advantages were thus obtained in the saving of stuff and labour, it must be observed, that an elevation of the supposed vertical ends of the twisted piece at each joint, and a vertical section of the said piece, were employed to obtain the inclination of the plane of the face of the mould, or that of the faces of the plank; this inclination was only correct when the planes of the faces of the plank were at right angles with the chord plane, or that passing through the chord of the plan of the wreath; but when inclined to the chord plane, required thicker stuff, in proportion to the degree of obliquity, whether more acute or more obtuse. - The method shewn in “the Guide,” was also the first attempt to spring the plank, that is, to make its plane rest upon three parts of the rail; and though the utmost degree of perfection was not attained, it has been of great use to workmen, as all the hand-rails of stairs in and about London, and in most parts of England, have been executed upon its principles for upwards of thirty years. To obtain still greater correctness, the inventor tried another method, by setting up three heights, supposed to be on the surface of a curved prism, in the middle of the rail ; but this, though still nearer than that published in “the Guide,” did not give him entire satisfaction; for the resting points being in the middle of the rail, the plane of section which formed the face- mould did not clear all the three sections without cutting into the solid of the wreath. - In the pursuit of truth, he was led to consider what would be the real resting points. It readily appeared, that a level line drawn towards the axis of the well-hole, might be made to coincide in every part with the top of the rail; that if the plane of the top of the plank be supposed to be placed on three vertical sections of the supposed rail in contact with a point in each, or coincident with the whole line of support of one of the sections, and with a point in each of the other two ; and the surface of the plank thus inclined be supposed to be prolonged, to intersect the horizontal plane of the base, the intersection would always point out the resting points, and shew their true seats upon the plan. From this consideration, it was evident that the resting point of each section, and consequently each seat, was that extremity of each section next to the intersecting line of the plane of the plank and that of the plan. This theory being applied to practice, has given the utmost satisfaction, both in the saving of stuff and time; the diagram for the face-mould is completely divested of all cross and oblique lines, and is, perhaps, in the most simple form to which it can possibly be reduced; the plane of section comes in con- tact with the tops of three vertical sections of the rail in every case whatever, and thus every desideratum is obtained by the most simple means. - Therefore, in practice, if we suppose the section of the rail to be two and a quarter inches horizontally in breadth, and two inches in thickness (as is generally the case,) a plank of two and a half inches thick will be sufficient for a rail, with any degree of concavity or convexity on the back. We shall now proceed to the illustration of the subject by the figures which represent the solids themselves:— Fig. 1, is a plan of the cylinder, with the elevation of the helical line, which is found by dividing the height into equal l parts, and the circumference of the base into equal parts also, then drawing the lines through the points of division, as in the figure. - - Fig. 2, a representation of the solid helix twisting round the A&A. cylinder, making a con- tinued rail upon a circu- lar plan; the curvature of the solid helix is, there- fore, every where the same. The rail is exhi- bited as squared; and . though it appears as one piece, it must be under- stood to consist of several wreaths, or lengths, screw- ed together, each length answering to a quadran- tal part of the plan. Fig. 3, shews the diffe- rent sections of a hol- low cylinder, cut entirely through the curved sur- face ; the solid exhibits a portion of the said cylin- der contained between two parallel planes : No. 1, shews the thickness of the section according to the inclination of the cut- ting plane; No. 2, shews the section of a semi- cylinder; and No. 3, that of an entire cylinder, cut according to the position of No. 1; the sections No. 2, and No. 3, being turned round, so that the plane of section may be brought into view, in order to make the solid appear. Fig. 4, exhibits a solid section of a hollow cylin- der, upon a quadrantal plan, with a small part straight; No. 1, exhibits the convex side, No. 2 the concave side. This figure shews the state of the rail-piece, as prepared by the face-mould, and is therefore bounded by two ** - concentric cylindrical surfaces, and two parallel planes. The Jºz. 4. ~\– A&2 - º falling mould being applied upon the convex side, the super- fluous wood is cut away according to a line drawn by the 440 H A R. H A R . DICTIONARY OF MECHANICAL SCIENCE. upper edge of the falling mould, in such, a manner that the stock of the square, being applied upon the convex side, paral- lel to the axis, the under edge of the blade may coincide with the top or winding surface of the rail-piece. the rail is regulated by running the stem of a gauge first upon the convex side, with the head upon the top or winding surface, and then the stem upon the concave side in the same manner, and cutting away the superfluous stuff between the two gauge lines. - - - - Fig. 5, exhibits the wreath, or rail-piece, as completely squared; No. 1, shews the concave side, with the lower end j or upper surface, and the higher end of the lower surface; and No. 2, the convex side of the cylindric surface, with the upper part of the back, and the lower part of the under side. . . . . The rail exhibited in fig. 2, is only a succession of wreaths, as in fig. 5. - From what has been shewn, it will be casy to conceive how a rail may be executed to any given, plan, and, to any develop- ment of the steps according to that plan. - - Though it may be possible to make a rail in one piece, as in fig. 3, No. 3, such a rail will hardly ever come into practice; the representations of the solid sections, in Nos. 2 and 3, are therefore not shewn with a view of being prepared for a rail, but to give a clear view of the different parts of the solid sec- tions of a hollow cylinder. - • HANSE Towns, port towns of Germany, of which Lubec and Hamburgh are the chief, They were formerly all of them inperial cities, and confederated for their mutual defence, and the protection of their trade. - HANDSPIKE, a wooden bar or lever to heave round the windlass, in order to raise the anchor from the bottom, or, for stowing the anchor, provisions, or cargo, in the ship’s hold. The gunner's Handspike is shorter than the former, and armed with two claws for managing the artillery. - - HANKS, wooden rings fixed upon the stays to confine the stay-sails thereto at different distances: they are used in lieu of grommets, being much more convenient, and of a later invention. They are framed by the bending of a tough piece of wood into the form of a wreath, and fastened at the two ends by means of notches, thereby retaining their circular figure and elasticity. - HARBOUR, a place where ships may ride safe at anchor, chiefly used in speaking of those secured by a boom and chain, and furnished with a mole. & HARBOUR Master, an officer appointed to see that the regulations of an harbour are strictly attended, to. HARD A LEE, the situation of the helm when it is pushed close to the lee side of a ship, in order to tack, or keep her head to the wind. Hence, HARD a Weather, when the helm is put close to the weather side of the ship in order to bear- away. HARDNESS, in Physiology, is the resistance opposed by a body to the separation of its particles. This property depends on the force of cohesion, or—on that which chemists call affinity, joined to the arrangement of the particles to their figure and other circumstances. - HARD Ness, or Rigidity, that quality in bodies by which their parts so cohere as not to yield inward, or give way to an external impulse, without instantly going beyond the dis- tance of their mutual attraction; and therefore are not subject i. º motion, in respect of each other, without breaking the ody. + HARE. See LEPUs. HARIOT, or Heriot, in Law, a due belonging to a lord at the death of his tenant, consisting of the best beast, either ox, horse, or cow, which he had at the time of his death, and in Some manors the best goods, piece of plate, &c. are called hariots. There is both hariot-service, and hariot-custom ; when a tenant holds by service to pay a hariot at his decease, which is expressly reserved in the deed of feofment, this is a hariot service: and where hariots have been customarily paid time out of mind after the death of a tenant for life, this is termed hariot-custom. For hariot-service, the lord may distrain any beast belonging to the tenant, that is on the land. For hariot-custom the lord is to seise, not distrain; but he The thickness of may seise the best beast that belonged to the tenant, though it. be out of the manor, or in the king’s highway, because he claims it as his proper goods by the death of his tenant. Nevertheless, where a woman marries and dies, the lord shall have no hariot-custom, because a femme-covert has no goods to pay as a hariot. . . . . - HARMATTAN, a wind which blows periodically from the interior parts of Africa towards the Atlantic. ocean. It pre- vails in December, January, and February, and is generally accompanied with a fog or haze that conceals the sun for whole days together. Extreme dryness is the characteristic of this wind; no dew falls during its continuance, which is some- times for a fortnight or more. The whole vegetable creation is withered, and the grass becomes at once like hay. The human body is also affected by it, so as to cause the skin to peel off, but it stops the progress of infection, and cures almost all cutaneous diseases. • . • HARMONICA, or ARMonic A, a musical instrument con- structed with drinking glasses. The glasses are blown as nearly as prssible in the form of hemispheres, having each an open neck or socket in the middle. The diameter of the largest glass is nine inches, and that of the smallest three inches ; between these are twenty-three different sizes, differing from . each other a quarter of an inch in diameter. When the glasses are tuned, they are fixed on a round spindle of hard iron, an inch in diameter at the thickest end, and tapering to a quar- ter of an inch at the smallest. The glasses are all placed within one another; the largest on the biggest end of the spindle, with the neck outwards; the next in size is put into the other, leaving about an inch of its brim above the brim of the first ; and the others are put on in the same order. From these exposed parts of each glass the tone is drawn by laying a finger upon one of them as the spindle and glasses turn round. The fingers should be first soaked in water, and rubbed occa- sionally, with fine chalk, to make them catch the glass, and bring out the tone more readily. The tones of this instrument are incomparably sweet beyond those of any other, and when it is once well tuned, it never again wants tuning. - - HARMONICAL ARITH Metic, is sometimes used for the application of numbers to the science of music. HARM on ICAL Curve, an ideal curve, into which a musical chord is supposed to be inflected, when put into such a motion as to excite sound. - - HARMONICAL Composition, in a general sense, includes both harmony and melody, i.e. of music or songs, both in a single part, and in several parts. s - - HARMONICAL Mean and Proportion. See Me AN and PRo- PORTION. - - HARMONICAL Sounds, such as always make number of vibrations in the time that one of the to which they are referred, makes one vibration. HARMONICS, that part of music which considers the differences and proportions of sounds with respect to the acut and grave: in contradistinction to rhyme and metre. HARMONY of THE SPHERes, a sort of music conceived b ancient philosophers, and supposed to be produced by the sweetly-tuned motions of the heavenly bodies. HARMONY, in Music, the agreeable result or union of several musical sounds heard at one and the same time. - HARMONY Figured. Figured harmony is that in which, for the purpose of melody, one or more of the parts of a composition move during the continuance of a chord, through certain notes which do not form any of the constituent parts of that chord. HARP, a stringed instrument, consisting of a triangular frame, and the cords of which are distended in parallel direc- tions from the upper parts to one of its sides. Its scale extends through the common compass, and the strings are tuned by semitonic interval. It stands erect, and when used, is placed at the feet of the performer, who produces its tones by the action of the thumb and fingers of both hands on the string. HARPOON, HARPING-IRoN, or HARPAGo, a spear or jave- lin, used to strike the whales in the Greenland and South Sea fisheries. The harpoon is furnished with a long shank, and has, at one end, a broad and flat triangular head, sharpened at both edges so as to penetrate the whale with facility: to the other end of this weapon is fastened a long cord called the a determinate fundamentals, H. A. T 441 . ° DICTIONARY OF MECHANICAL SCIENCE. whale-line, which lies carefully coiled in the boat in such a manner as to run out without being interrupted or entangled. As soon as the boat has rowed within a competent distance of the whale, the harpooner launches his instrument, (on the upper end of which, near the ring, his name is generally engraved,) and the fish being wounded, immediately descends under the ice with amazing rapidity, carrying the harpoon along with him, and a considerable length of the line, which is purposely let down, to give him room to dive. Being soon exhausted with the fatigue and loss of blood, he reascends in order to breathe, where he presently expires, and floats upon the sur- face of the water, when they approach the carcase by drawing in the whale-line. The line is sixty to seventy fathoms long, and made of the finest and softest hemp, that it may slip the easier; if not well watered, by its friction against the boat, it would soon be set on fire; and if not sufficiently long, it would be soon overset, as it frequently is. With the harpoon they also catch other large fish, as Sturgeons, &c. HARPSICHORD, a stringed instrument, consisting of a case framed of mahogany or walnut-tree wood, and containing the belly or sounding-board over which the wires are distended supported by bridges. In the front the keys are disposed, the long ones of which are the naturals, and the short ones the sharps and flats. These keys being pressed by the fingers, their enclosed extremities raise little upright oblong slips of wood called jacks, furnished with crow-quill plectrums, which strike the wires. The 'great advantage of the harpsichord beyond most other stringed instruments, consists in its capacity of sounding many notes at once, and forming those combina- tions, and performing those evolutions of harmony, which a single instrument cannot command. g e tº HARRIOT, Thom As, an eminent English mathematician and astronomer, was born at Oxford in 1560; who, before he was twenty years of age, had acquired so great a reputation for his mathematical knowledge, that he was appointed preceptor to Sir Walter Raleigh, who was ever after his steady patron. HART'S HoRN, the horns of the common male deer, to which many very extraordinary medicinal virtues were attri- buted, and indeed to nearly all parts of its body; but the expe- rience of late years gives no countenance to them. The horns are of nearly the same nature as bones, and the preparations of them by heat are similar to those from solid animal sub- stances in general. Consequently the articles denominated spirit of hartshorn, and salt of hartshorn, though formerly obtained only from the horns of different species of deer, are now chiefly prepared from bones. The former of these, which is a j. alkali of very penetrating nature, is an efficacious remedy in nervous complaints and fainting-fits: and salt of hartshorn has been successfully prescribed in fevers. The scrapings or raspings of the horns, under the name of hartshorn shavings, are variously employed in medicine. Boiled in water, the horns of deer give out an emollient jelly, which is said to be remarkably nutritive. Burnt hart's horn is employed in medi- cine. The horns of the stag are used by cutlers and other mechanics for the handles of knives and cutting instruments of different kinds. - - HARVEST FLY, in Zöology, a large four-winged fly of the cicada kind. HAT MAKING. Hats are commonly made of wool, or of fea- thers, or of straw. The wools of kids, hares, rabbits, and beavers are used to cover the original material in all woollen hats; and in general the quality of the hat depends on the proportions of good or fine wool employed in its manufacture. The different processes in hat-making are bowing, hardening, working, shaping, dying, stiffening, steaming, and ironing. Bowing, consists in teasing or dressing the wool by means of a hand bow which the workman twangs with a knobbed stick. Hardening is merely the pressing of the wool so bowed to make it bear handling, by means of a cloth that covers the stuff, and enables the hatter to form it into a conical shape. Working is done by a battery, consisting of a kettle of water (acidulated with sulphuric acid) and eight planks of wood join- ed together, and meeting in the kettle at the middle. The liquor being heated, the article is dipped from time to time, and worked on the planks with a roller, and by rolling it up, and opening it again. Shape is given by laying the conical cap on a block, the size of the crown of the hat, and thus tying it round, with a packthread, called a commander, and afterwards with a piece of iron, or copper bent for the purpose, the workman gradually drives down the commander all around, till he has reached the bottom of the block, and the crown is formed ; what remains below the string, is the brim. Dyeing. The nap of the hat being raised with a wire brush, it is dyed in a liquid prepared of logwood, and green copperas, and blue vitriol, the sulphates of iron and copper. The copper holds ten or twelve dozen hats, which are kept boiling for three-quar- ters of an hour, when they are taken out and set to cool, and returned to the dye; and this ten or twelve times successively. Stiffening is effected with beer grounds and glue. The work- man has two boilers, one the grounds of strong beer, applied to the inside of the crown, to prevent the glue from oozing through ; another containing the glue stiffening, applied after the beer-grounds are dried, and then only upon the lower face of the flap, and the inside of the crown. Steaming. The hat is now placed on the steaming-bason, which is a small hearth, or fire-place, raised three feet high, with an iron plate over it, exactly covering the hearth. On this plate the workman first Spreads cloths, which being sprinkled with water to secure the hat from burning, it is placed on them with the brim downwards. When moderately hot, the workman strikes gently on the brim with the flat of his hand, to make the jointings incorporate, so as not to appear. Ironing. The hat is put again on the block, and brushed and ironed on a bench, called the stall-board. This is performed with an iron like that used in ironing linen; which being rubbed over each part of the hat, with the assist- ance of the brush, smooths and gives it a gloss. The hat is then lined and trimmed for sale. These latter operations are for the most part performed by women. - HATCH, or HATCHWAY, a square or oblong opening in a ship's deck, forming a passage from one deck to another, or from the deck to the hold. In large ships there are several hatchways, as the fore, the main, and the after hatchways. In fact, hatches are moveable trap-doors. HATCHES, also denote flood-gates stop the current of the water. - HATCHING, the maturating fecundated eggs, whether by the incubation and warmth of the parent bird, or by artificial heat, so as to produce young chickens alive. The art of hatching chickens by means of ovens, has long been practised in Egypt; but it is there only known to the inhabitants of a single village named Berme, and to those that live at a small distance from it. Towards the begining of autumn, they scatter themselves all over the country, where each person among them is ready to undertake the manage- ment of an oven, each of which is of a different size, but in general they are capable of containing from forty to fourscore thousand eggs. The number of these ovens placed up and down the country is about thre hundred and eighty six, and they usually keep them working for about six months. As therefore, each brood takes up, in an oven, as under a hen, only twenty-one days, it is easy in every one of them to hatch eight different broods of chickens. Every Bermean is under the obligation of delivering to the person who intrusts him with an oven, only two-thirds of as many chickens as there have been eggs put under his care; and he is a gainer by this bargain, as more than two-thirds of the eggs usually produce chickens. In order to make a calculation of the number of chickens yearly so hatched in Egypt, it has been supposed that only two- thirds of the eggs are hatched, and that each brood consists of at least thirty thousand chickens: and thus it would appear that the ovens of Egypt give life yearly to at least ninety-two millions six hundred and forty thousand of these animals HATCHING of Fish. The Chinese hatch the spawn of fish, by collecting it on the margin and surface of the water, and then filling the shell of a newly laid egg with the gelatinous matter which contains the spawn. The hole in the egg is waxed over, and it is put under a sitting hen. At the expira- tion of a certain number of days, they break the shell in water warmed by the sun. The young fry are presently hatched, and are kept in pure fresh water till they are large enough to be thrown into the pond with the old fish. The sale of spawn set in a river, &c. to for this purpose forms an important article of trade in China, 5 U 442 H E A H E A , DICTIONARY OF MECHANICAL SCIENCE. : HATCHMENT, in Heraldry, is the coat of arms of a dead person, usually placed on the front of a house, by which is known the rank of the deceased person while living, whether bachelor, maid; husband, wife; widow, or widower, &c. , HAUL The WIND, (to) to direct the ship's course nearer to fhat point of the compass from which the wind arises: for instance—suppose a ship sails south-west with the wind northerly, and some particular occasion renders it necessary to haul the wind further to the westward: to perform this ope- ration, it is necessary to arrange the sails more obliquely with: her keel; to brace the yards more forward by slackening the starboard, and pulling in the larboard braces, and to haul the lower sheets further aft, and finally to put the helm aport, i. e. over the larboard side of the vessel. turned directly to the westward, and her sails are trimmed accordingly, she is said to have hauled the wind four points, that is to say, from S. W. to W. She may still go two points nearer to the direction of the wind, by disposing her sails according to the greatest obliquity, or, in the sea-phrase, by trimming all sharp ; and in this situation she is said to be close-hauled, as sailing W. N. W. HAUTBOY, a musical instrument of the wind kind, shaped much like the flute, only that it spreads and widens towards the bottom, and is sounded through a reed. HAW Finch, in Ornithology, the English name of a bird known among authors by the name of coccothraustes. HAWKERS and PeplARs, are such dealers or itinerary petty chapmen who travel to different fairs or towns with goods or wares, and are placed under the control of commissioners, by whom they are licensed for that purpose, pursuant to stat. 8 and 9 William III. c. 25, and 29 Geo. III. G. 26. Traders in linen and woollen, sending goods to markets and fairs, and selling them by wholesale ; manufacturers selling their own manufactures, and makers and sellers of English bone-lace, going from house to house, &c. are excepted out of the acts, and not to be taken as hawkers. HAWSE, the situation of the cables of a ship when moored with two anchors, one on each bow. When the cables cross each other, and rub together, the hawse is foul. Hawse P(ugs are thrust into the hawse holes to keep out the water. HAZARD, a game on dice, without tables. It is played with only two dice, and as many may play at it as can stand round the largest round table. Two things are chiefly to be observed, viz. main and chance, the latter belonging to the caster, and the former, or main, to the 6ther gamesters. There can be no main thrown above mine, nor under five, so that five, six, seven, eight, and nine, are the only mains flung at hazard. Chances and nicks are from four to ten; thus, four is a chance to nine, five to eight, six to seven, seven to six, eight to five ; and nine and ten a ohance to five, six, seven, and eight; in short, four, five, six, seven, eight, nine, and ten, are chances to any main, if any of these nick it not. Now nicks are either when the chance is the same with the main, as five and five, or the like; or six and twelve, seven and eleven, eight and twelve. Here observe, that twelve is out to nine, seven, and five; eleven is out to nine, eight, six, and five, and ames-ace and deuce-ace, are out to all mains whatever. HEAD, an ornamental figure erected on the continuation of a ship's stem, as being expressive of her name, and emblema- tical of war, navigation, commerce, &c. rical, as referring to some of the deities or heroes of antiquity; or allegorical, as alluding to some of the natural consequences of battle, or the virtues most essential to life exposed to per- petual danger. . Thus, in the former sense, they represent a Neptune, an Alcides, a Mars, an Achilles, a Minerva, or a Jason; and in the latter they produce a Magnanimous, an Intrepid, a Revenge, or a Victory. Image heads are those founded on practical fiction, and should be bold, warlike, and classical,—such as Hercules brandishing his club over the Jheads of Cerberus; Jupiter riding on his eagle, and armed with his thunders, &c. Emblematic heads consist of appro- priate figures,-such as an eagle, denoting dignity, force, and velocity; a dragon, denoting power, vigilance, &c. HEAD, is also used in a more enlarged sense, to signify the As soon as her head is, º to a tº The heads which have any affinity to war or navigation, are in general either histo- whole front or forepart of a ship, including the bows on each side; the head therefore opens the column of water through which the ship passes when advancing; hence we say, Head- sails, Head-way, Head-sea, &c. . It is evident that the forepart of a ship is called its head, from the affinity of motion and position it bears to a fish, and in general to the horizontal situa- tion of all animals while swimming. Thus, fig. 1 represents one side of the forepart of the head o. a 74-gun ship, together with part of the bow keel, and gunnel, which will be better understood from this description:-AA, the keel; a, a, false keels; A C, the stem; a, a, the cat head; b,b, its props, or supporter; c, e, the knight head, or bollard timber which secures the inner end of the bowsprit; d, d, the łº, º e, e, the naval hoods; f, the davit-chock; g, the {1||||K 1030, Fig.1. H H, gun ports of the lower deck; h, gun ports of the upper deck. I, I, the channel, with their dead eyes and chain plate. i, the gripe or fore foot, which unites the keel with the stern, forming a part of either. h, k, the decks; l, the convexity of the beams; m, m, timbers of the head and part of the bowsprit; X, the rails of the head lying across the timbers; Q Z, the forepart of the main Wale; R X, forepart of the channel wale. U C, the load water line. Fig. 2 represents the head view of a ship, with the projection of her principal timbers and all the planks laid on one side, Fig.2. H E A -II E I '443 DICTIONARY OF MECHANICAL scIENGE. HEADBORROW, or Headborough, the chief of the frank. pledge. He was called also burrowhead, bursholder, third-bur- row, tithing-man, chief-pledge, or burrow-elder. He is now occasionally called a constable." HEALTH, is a right disposition of the body, and all its parts. HEARING. See Sound. The organ of hearing is the ear, and particularly the auditory nerve and membrane. HEAT, in Natural Philosophy, is one of the effects of fire or caloric, indicated by an increase of temperature, and the sensation it produces on the organs of feeling. Various hypo- | theses have been advanced, both by ancient and modern philo- sophers, to account for the phenomena of heat, some consider- ing it as a body, sui generis, and others only as a quality common to all bodies. It would answer very little purpose, if our limits would admit of it, to detail the various notions that have been advanced on this subject; we shall, therefore, merely state the opinions of some of the best informed philo- sophers amongst the moderns, though the grand question, as to the materiality of heat, is not yet satisfactorily determined. With respect to the solar heat, we observe then, that, by pre- sent opinion, the sun’s rays are twofold; one sort emits light, the other heat; called in science calorific and luminous rays. This division of the solar rays into calorific and luminous, established as it is upon such undoubted premises, Dr. Thomp- son considers as nearly putting an end to the dispute, by demonstrating the existence of caloric as a peculiar substance; at least it is putting it upon the same footing in this respect as light, the materiality of which is not disputed by many who argue on the other side with regard to heat. The greatest degrees of heat which are known, have been produced by con- centrating the solar rays with a mirror, or lens, or by supply- The greatest degree of cold ing a blow-pipe with oxygen gas. known to have been produced, has been obtained by mixing snow with certain salts, as muriat of lime. If this be mixed with dry, light snow, and stirred well together, the cold pro- duced will be so intense, as to freeze mercury in a few minutes. Salt and snow also produce a great degree of cold. Heat Animal. The temperature which animals, and even vegetables, maintain during life, above that of surrounding objects, is a very striking phenomenon. By general analogies, it has frequently been referred to the process of combustion; and from facts more distinctly pointed, the doctrine, that it depends upon the absorption of oxygen, has been advanced by modern chemists. It has, however, been found, by actual expc- riment, that the lungs of animals are usually the coldest part of the body; and hence it has been doubted whether the above theory was correct, and recourse has been had to the supposi- tion, that animal heat was the effect of electricity. HEAT, in, Geography, the diversity of heat of climates and seasons arising chiefly from the different angles under which the sun's rays strike upon the surface of the earth. The differ- ent degrees of heat and cold in different places depend, how- ever, in a very great measure, upon the accidents of situation with regard to mountains and valleys, and the soil. The following table of the heat of different climates is com- puted for every tenth degree of latitude, to the equinoctial and tropical sun ; by which an estimate may be made of the intermediate degrees. Lat. Sun in Aries and Sun in Cancer. Sun in Capricorn. Libra. 0. 20000 18341 . . j834.1 10 19696 20290 15854 20. 18797 2.1737 I 3166 30 17321 22651 10.124 40 15321 23048 6944 50 12855 22091 3798 6() 10000 22/73 1075 70 6840 23543 000 80 3473 24673 000 0 0000 25055 000 | Latent Heat, is a phrase used by Dr. Black, arising from the discovery that a large portion of heat sometimes dis- ye appears, or is absorbed by a body, without any increase of temperature. This commonly happens when a body from a Solid becomes liquid, or from a liquid becomes aériform; and sometimes, when two bodies of the same temperature combine, a great degree of cold is produced; but when a due portion of heat is acquired from the surrounding bodies, the temperature is restored. The heat which disappears in these cases is what is called lutent point. See Evaporation. - HEATH. See ERICA. HEAVEN, in the Ancient Astronomy, denoted an orb or circular region of the ethereal heaven. The ancient astrono- mers assumed as many different heavens as they observed different celestial motions. These they supposed to be all solid, as thinking they could not otherwise sustain the bodies fixed in them ; and spherical, that being the most proper form for motion. Thus they have seven heavens for the seven planets, the Moon, Mercury, Venus, the Sun, Mars, Jupiter, and Saturn. The eighth was the fixed stars, which was par. ticularly denominated the firmament. Ptolemy adds a ninth heaven, which he calls the primum mobile: after him two crys- talline heavens were added by Alphonso, king of Castile, to account for-some irregularities in the motions of the other heavens: and, lastly, an empyrean heaven was drawn over the whole, for the residence of the Deity; which made, in all, twelve heavens. . But others admitted many more heavens, according as their different views and hypotheses required; Eudoxus supposed 23, Regiomontanus 33, Aristotle 47, and Fracaster no less than 70. " HEAVINESS, in general the same with Gravity and Weight. , HEDERA, or Ivy, a genus of the pentandria monogynia class and order. Natural order of hederaceae. Caprifolia, Jussieu. There are six species, with several varieties. The roots of the helix or ivy are used by leather-cutters to whet their knives upon. Apricots and peaches covered with ivy during the month of February, have been observed to bear fruit plentifully. The leaves have a nauseous taste; they are given to children in Germany, as a specific for the atrophy. The common people of England apply them to issues; and an ointment made from them is in great esteem among the High- landers of Scotland as a ready cure for burns. Horses and sheep eat the plant; goats and cows, refuse it. HEDGES, in agriculture, are either planted to make fences round enclosures, or to divide the several parts of a garden. When designed as outward fences, they are planted either with hawthorn, crabs, or blackthorn ; but for gardens, some prefer evergreens, in which case the holly is best, next the yew, then the laurel, laurustimus, philly rea, &c.; others prefer | the beech, the hornbeam, and the elm. HEDYSARUM, in Botany, a genus of the Diadelphia Decandria class and order. Natural order of Papilionaceae or Leguminosae. Essential character: corolla keel transversely obtuse; legume jointed, with one seed in each joint. There are ninety species, only one of which is a native of Great Britain; viz., H. onobrychis saintfoin, or cockshead, and but ten which are natives of Europe. Most of these are perennial. HEGIRA, in Chronology, signifies the epoch or account of time used by the Mahomedans, who begin their computation from the day that Mahomet was obliged to abandon the city of Mecca, July 16, 622. The years of the hegira are lunar ones, of 354 days; and therefore to reduce these to the Julian Calen- dar, we must multiply the years of the hegira by 354, and divide the product by 365}; to which add 622, the date at which this epoch commenced, and the result will be the Julian year required. º HEIGHTS and DistANces, The Mensuration of. In the mensuration of heights and distances, instruments of various kinds are used for determining angles, and the distances between remote and inaccessible objects. The fittest instru- ment for taking vertical or horizontal angles, is a theodolite, fur- nished with a compass and level, one or two telescopes, and a | vertical arc. Angles oblique to the horizon may be taken with a Hadley's quadrant or sea:tant, and then reduced by calculation to their projection on the horizontal plane. Angles, both hori- zontal and vertical, may also be taken with Hadley's quadrant; observing, that in near objects the quadrant is to be adjusted to the direct object; and that, in taking vertical angles with it, an 444 H E . I H E I DictionARY OF MECHANICAL scIENCE. artificial horizon should be used, and the image of the object, reflected from the glasses of the quadrant, brought to coincide with that in the artificial horizon. See THEODOLITE and QUADRANT. See ALTITUDE, from pages 28 to 31. Bases or distances may be measured with Gunter's chain, or the common 50 feet tapes, or poles, or rods, of a convenient length, and formed of such matter as is least liable to contract or expand in length, during the measurement. The use of instruments is best acquired under the direction of a person practically acquainted with their application and several adjustments. - Problem 1.—To find the height of an accessible object.—Rule. Measure the distance between the bottom of the object, and any convenient station, on the same horizontal plane; and at that station observe the angle of elevation. Then say, As radius is to the tangent of the angle of elevation, so is the horizontal distance to the height of the object above the hori- zontal plane passing through the eye of the observer, to which the height of the eye being added, the sum will be the height of the object. See Probs. 1 and 4, ALTITUDE. Example.—Let the horizontal distance A B (fig. 1) be 200 feet, and the angle of elevation CD E 37° 35', the height of the eye being 5 feet; what is the height of the object B C : As radius - = T. 450 = 10:0000000 To tangent CD E - 370 35' = 9.8862878 So is distance A B – 200 = 2°30'10300 To the height CE = 153-92 = 2, 1873.178 Add height of the eye - 5 **me Height of the object B C = 158-92 Remarks. 1. In measuring heights, the station of the observer. should be chosen so, that the angle of elevation may be as near to 45° as possible, because the less error in the altitude will arise from an error in the angle, the nearer the angle is to 45°. 2. When the angle of elevation is 45°, the height above the plane of the eye will be equal to the distance; when the angle is 26° 34', the height will be equal to half the distance, and when the angle is 30°, the height will be equal to half the hypotenuse. - - The angle of depression FC D is – the angle of elevation E D C, for they are alternate angles, and FC is parallel to D E. Fig. 1. Fig. 2. E" → C ~ E. A- B A. B C Problem 2–To find the height of an inaccessible object.—Rule. Let C D (fig. 2) represent the object of which the height is to be found ; at any two convenient stations A and B, in the same vertical plane with CD, observe the angles of elevation D A C, DB C, and measure the distance AB. Then, because the exterior angle D B C is equal to the two interior angles B D A, D A B; if D A B be subtracted from D B C, the angle B D A will remain. Now, in the triangle D A B, as sine D is to sine A, so is A B to B. D.; and in the triangle D B C, as sine C (rad.) to sine B, so is B D to C D. See Probs. I and 5, ALTITUDE, where, in fact, these two problems are given; and their intro- duction here is defensible on no other ground than the Alpha- betical Title of our work, for we abjure repetition as needless waste of our own property. Example.—The angle of elevation of a tower at a station on the same horizontal plane was 48°, and at another station, on a level with the former, and 200 feet farther off, in the same direction, the angle of elevation was 26°45, the height of the eye being 5 feet; what was the height of the tower? - |: 489 – 26°45 = 21° 15 = AD B. To find B.D. - To find C D. - : S,ADB = 21° 15'-9:5592338): S,C 909-10. 000000 : S,DAB = 26° 45'-9-65.33075|: S, DBC 489- 9:8710735 ; : A B. F 200–23010300|: : B D = 248:37– 2:395.1037 : B D – 248°37–2°395.1037|: C D .2°266.1772 Height of the eye 5° Height of the tower 189'57 feet. The operation may be performed rather more concisely, as follows:–To the sines of the observed angles of elevation add the co-secant of the difference between these angles, and the logarithm of the distance between the stations A and B, the sum, rejecting 30 from the index, will be the logarithm of the height of the object. = - 184'57– Problem 3.—Given the angles of elevation of any distant object, taken at three places in a horizontal straight, line, which does not pass through the point directly below the object; and the respective distances between the stations; to find the height of the object, and its distance from either station. Let AEC (fig. 3) be the horizontal plane, E O the perpen- dicular height of the object O above that plane, A, B, C, the Fig. 3. three places of ob- - servation, O_A E, O B E, O C E, the respective angles of elevation, and A B, B C, the given dis- tances. Since the triangles A E O, B E O, C E O, are all right-angled at E, the distances AE, BE, CE, will evi- dently be as the co- tangents of the an- gles of elevation at A, B, ¥3, respective- ly. Now the point E may bc determin- cd, so that those * G - e a • a s "" tº e º * * * , * * *s, lines may have that ratio as follows:– Construction.—Find A D, DC, thus, Cot B : Cot C : : A B : A D, and Cot B : Cot A : : B C : CD. Make the triangle A DC, about which describe a circle. Join D B, and produce it till it meet the circle in E, the point in the horizontal plane perpendicularly below O;—or, the point E may be found with- out describing the circle, thus: Having found A D, CD, as before, and made the triangle A DC, join D B, and draw A.E so that the angle E A C may be equal to the angle B D C ; then will A E meet B D produced in E. Solution.—In the triangle A CD, of which the three sides are known, find the angle C.A. D. Again, in the triangle A B D, of which the sides A B, A D, and the included angie B A D are known, find the side BD. Then, because the triangles BD C, B A E, are similar, and also the triangles B D A, B C E, as B D : C D :: A B : A E ; also, B D : A B : : B C : B E, and B D : A D : : B C : C E. Lastly, Radius : Tan. angle of elevation at A, B, or C : : the distance of E from that sta- tion : the height (EO) required. - Example.—Three observers, A, B, C, in a straight line, take, at the same instant, on a signal, the altitude of a balloon. A finds it 15°, B 18°, and C 209; also, B is 1000 yards from A, and C 1500 yards from B; the perpendicular height of the balloon is required 2 w To find the line A D. To find the line CD. : Cot B = 189 = 0°4882240ſ: Cot B - 18O = 0°4882240 . Cot C – 209 E 0°4389341 : Cot A - 150 = 0°57'19475 ..: A B ~ 1000 E 3 000000|: : B C = 1500 - 3-1760913 A D = 892.709 – 29507101 (; C D = 1818,925- 3.239slas H E I H E I 445 .DICTIONAIRY OF MECHANICAL SCIENCE. To find the angle C A D. A C = 2500 - log. 3°39794.00 AD = 892,709 ............ 29507101 C D = 1818'925 . . . . . . . . . . . . 6'3486501 2) 5211.634 - 13°6513499 2605'817 log. 3°4159439 186'892 • e s e o e o 'o e º a • 2°8959.151 19°9632089 16o 33' 32" COS. 9'9816044 2 - 33° 7' 4" = the angle C A D. To find the line B D. B A + A D = 1892,709 = 3.2770889 : B A — A D = 107.291 = 20305633 :: Tang. (D + B) = 73° 26' 28' = 10:5267586 : Tang. # (D – B - 100 471 38" - 9:2802380 The angle A BD - 62o 38' 50 - Hence, Sine Z. A B D : Sine B A D :: A B : B D. i. e. S, A B D = 62° 38' 50" = 9.9485080 : S, B A D = 33° 7' 4" - 9.7374804 : : A D - 892.709 = 2.9507101 B D - 549° 139 - 2.7394825 To find A E. To find E 0. B D = 2.7396825 Rad. Sime 909 - 10'0000000 : C D = 32598148 : Tang. 15” – 9: 4280.525 :: A B = 3:00000000 : : A E - 3’5201323 *- gº-ºº: : A E = 3312:32 = 3.5201325 E O - 887°53 – 2.9481848 Problem 4–To find the distance of an inaccessible object, fig. 4.—Let C be JFig. 4 - º 9. any inaccessible object, and A, C. B, points from which the dis- tance of that ob- ject is to be found. Measure the distance AB, and observe the angles B A C, A. T} IB ABC. Then sine C : sine B : : B A : A C ; and, sine C : sine A. : : A B : B C. Eacample.—Let the angle A be 86° 52', the angle B 78° 47', and the base A B 10,110 feet; what is the distance between A and C2 Here by the Rule. : Sine z c = 14° 21' = 9.3941794 : Sine Z. B = = 9'991624.1 - : : A B - = 4'0017512 78 47 10,110 wºma- : A C = 40012.5 – 46021959 or, A C is 7 miles 4 fur. 137 yards 13 feet. Fig. 5. The distances A C, B C, fig. 5, may be determined without the aid of an instru- ment to measure the angles, thus:—Continue C A, C B, to any two points F, G, and measure A B, AF, A G, B F - B G ; then the three sides of the triangles A B G, BA F, being known, the angles AB G. and B A F may be found, and consequently their supple- ; : AB = 1000 – : B C ~ 2305-75 – 3:3628.127|: ments C B A, C A B; from which compute A C, B C, by the rule. The perpendicular distance D C may be found thus:--Calculate either side as A C by the rule, then from A C and the adjacent angle A, find D.C. Or, produce C A to F, fig. 6, C B to G. ; measure off AO = GA B, and trace O F parallel to B G ; then the triangle O FA is equal and similar to the triangle A. C. B. Consequently, if from the vertex F we trace a line FK perpendicular to A O ; this new line K F = C D. - Problem 5.--Tofind the distance between two objects (A and B), the distance of each from a third object (C) being known, and also the angle (C) at that object which the required distance subtends. Rule. Let AC, B C, and the angle ACB be given (fig. 7) from these data, it is plain that A B may be found by the rule for the second case of Plane Tri- C *w gonometry; or, A B- V (AC2 { ſº + B C” – 2 A. C. B. C. cos. C.) £, 42. Z Bacample.—An order to de- A. I} Fig. 6. Fig. 7, termine the distance between two houses A and B, which could not be done by direct measurement, I measured the distance of each of them from a point C, viz. A C E 600 yards, B C 700 yards, then at C, I took the angle A C B = 56°12'. Required the distance A B : : B C + A C – 1300 – 3:1139434 : B C — A C - 100 = 2.0000000 :: Tan 3 (A + B) = 61°54′ = 10:2724992 : Tan 3 (A – B) = 8°11'52" = 9:1585558 A - 700 5' 52" : S,A = 700 5'52" = 99732549 : S,C = 56 12 = 9.9195929 ; : B C - 700 – 2.8450980 A B ~ 618-63 - 2,7914360 or AB = x/ (600? -- 700? – 1200 x 700 x 556296) = 618.63 yards. Remark.-If the lines measured from A and B to C be con- tinued beyond C, till the parts of them beyond C be equal to A C, B C, then will the distance between the extremities of the lines so continued, be equal to that between A and B, without calculation. Problem 6. — To find the distance between two inaccessible objects.—Rule. Let C and D (fig. 8) be two inaccessible objects, Fig. 8. the distance between which is C aſ p required. Measure any base * A B; at A find the angles # C A D, D A B, and at B find the angles A B C, CB D. In the triangle A B C, in which the angles and the side A B are given, find C B ; in like manner, in the triangle A B D, find B D. Then in the triangle C B D, of which the sides C B, A. }} B D, and the included angle CBD, are given, find the side CD. - Example.—Let C and D be two houses on the further side of a river; required their distance, from the following data, viz. A B = 1000 links, the angle C A D = 42°45', D A B = 54° 12, A B C = 57° 33', and C B D = 50°19'? 1. In A B C, to find B C. 2. In A B D, to find B.D. s,c = 25°30′ = 9:6339844: S, D = 17°56' = 9.4884240 S,A = 96°57' = 9.9967971 |: S,A = 54°12' = 9.9090550 3.0000000|: : A B ~ 1000 - 3:0000000 IB D = 2634'09– 3°4206310 5 X H E I H E I DICTIONARY OF MECHANICAI, sor ENCE. 3. In CBD, to find an angle CD. : B D + B C. - 4939.84 = 3-6937129 : B D – B C = 328-34 = 2.5163238 .:: Tan # (C + D) = 64° 50' 30" = 10:3282013 : Tan 3 (C — D) = 8° 3' 18" = 8.1508.122 B C D - 72° 53' 48" : S,C = 72° 53' 48" = 9.9803561 : S, B = 50° 19. = 9'8862568 : : B D = 2634'09 – 3'4206310 : CD - 2120-95 = 3:3265317 2120.95 links. º - In like manner, the distances, taken two and two, between any number of remote objects placed around a base line, may be determined. w Problem 8–Given the distances between three objects (A, B, C,) and the angular distances between these objects at a station (S) in the same plane, to find the distance between that station and each of the objects. - sº Of this problem there are several cases. fi Case 1. When the station S is without the triangle A B C, g. 9. Construction. Make the tri- angle A B C ; at A, make the angle D A B = the given angle DS B or CS B; at B, make the angle A B D = A S C or A SD. Then through the points. A, B, D, describe a circle; join DC, and produce it till itmeet the circle in S, the station of the observer; and join SA, S B t Solation. In the triangle A B C, of which the three sides are known, find the angle - B.A. C. In the triangle A B D, of which the angles and the side A B are known, find the side A D. In the triangle C A D, of which two sides A C, A D, and the included angle C A D are known, find the angle A CD. In the triangle A S C, of which the angles and the side A C are known, find the sides S.A., S C. And in the triangle AS B, of which the angles and the side A B are known, find S B. Case 2. When the station S is within the triangle A B C, as in fig. 10. Construction: Make the tri- angle A B C ; make the angles BAD, A B D equal to the sup- plements of the given angles BS C, A S C, respectively. Through the points A, B, D, describe a circle ; join D C, D which will cut the circle in S, the station of the observer. Solution. This case is calcu- lated in the same manner as the last. - Case 3. When the three ob- jects are in one straight line, º 3. in fig. 11. - Fig. 11. Construction. This case is ID constructed in the same man- ner as Case 1. Solution. In the triangle A DC, of which the angles and the side A C are known, A — c find A. D. In the triangle - A B D, of which the sides A B, A D, and the included angle B A D are known, find the angle A B D = S B C ;. the supplement of which ABS Fig. 10. B Fig. 12. = D B C. In the triangle - A B S, of which the angles S and the side A B are known, A. find S.A., S. B. And in the * - triangle A S C, of which the angles and A C are known, or in the triangle B SC, of which the angles and B C are known, find S C. Case 4. When the station S is in one of the sides of the B triangle, or in one of the sides produced, as in figs. 12 and 13. Solution. Find the angle B A C from the three sides. Then, when S is situate as in fig. 13, the angles of the triangle A S C, and the side A C, are given to find C S, A S, and consequently B S. And when S is situate as in fig. 12, the angles of the tri- angle S A B, and the side A B, are given to find BS, A S, and consequently C S. Example 1.-There are three objects A, B, C, (fig. 9) the dis- tances of which from one another are as follows:—A D = 424, A C = 213, and B C = 262 yards; I desire to know my dis- tance from each of these objects at a station S without the triangle A B C, where I observed the angle ASC to be = 13° 30', and BS C = 29° 50' A. S £ B AB = 424 log. 26273659 2. In ABD to find AD. A C = 213 log. 2.3283796 —|*: S, D = 136°40′ = 9.8364771 B C = 262 4'955.7455|| *ms tº *- —|: S, B = 13° 30' = 9-3681853 2 \ 899 15'0442545|: : A B — 424 - 2.6273659 449.5 log 2.6527297 *=mºsºme 187°5 log. 2'2730013]: A D - 144'236 – 2:1590741 2) 1996.99855 14° 58' 33” cos. 9.9849927 2 290 57' 6" - B A C 3. In A CD to find the angle C. A C + A D = 357.236 = 2.5529552 : A C – A D – 68°764 = 1°837361 l ; : Tan 3 (D + C) = 60' 6' 27" = 102404445 Tang (D – C) = 18° 30' 47" = 9.5248504 C - 41° 35' 4" supplement of the angle A C S, and also the exterior angle of the triangle AS C ; whence, 180° — A C I) = A CS, and A C D – A SC – C A S. 4. In A S B to find B.S. 15. In A C S to find AS and C.S. S,S = 43° 20' = 9.8364771|: S, S= 13°30′ =9-3681853 : S,A = 58°2'46"- 9.9286387|: S,C-138°24'20" =9.8220724 :: A B = 424 = 2.6273659|:: A C-213' -2'32837.96 B s = 524286 = 27,95275]: A s—605-712 =27822667 : S,S=13° 30' -9-3681853 : S,A=28° 5' 40" =9'6729530 ; : AC-213' =2.32837.96 Cs—429,682 =26331473 Example. 2.-There are three objects A, B, C, fig. 9, the distances of which from one another are as follows:–A B = 314 yards, A C = 280 yards, and B C = 326; how far am I from each of these objects at a station S without the triangle * The angle A B D is equal to the observed angle A SC, because they stand on the same arc A.D., (Eucl. iii. 21;) for the same reason B A D = B S C. HE L H E L 447 DICTIONARY OF MECHANIC AL SCIENCE, A B C, where I observed the angle A S C to be = 25°42', and B S C - 23° 6' 2 - - 2. The distances between three objects A, B, C, (fig. 10,) are as follows:–AB = 267 yards, A C = 346, and B C = 209 ; and the angles at a point (S) within the triangle A B C, sub- tended by those distances, are 128° 40', 140°, and 91° 20', re- spectively; what is the distance of the point S from each of the objects 7 - 3. If the three objects, A, B, C, as seen from S, be situate as in fig. 12, and A B be - 1224 chains, B C = 73.6 chains, A C = 81-8 chains, and the angle S = 22° 44' 40". Required the distances S.A., S B, and SC 7 - - 4. If the three objects, A, B, C, as seen from S, be situate as in fig. 13, and A B be = 1224 chains, B C = 73-6, A C = 81-8, and the angle A S C = 110°. Required the distances S.A., SB, S C ; - - 5. If the three objects, A, B, C, as seen from S, be situate as in fig.11, and A B be = 2550 yards, A C = 7000 yards, the angles AS B = 25° 15', and B S C = 35° 30'. Required the distances S.A., SB, S C ! Problem 9.—To find the distance of the visible horizon, fig. 14.— jºule 1. To the diameter of Fig. 14 the earth add the height of the de eye, and to the logarithm of A the sum add the logarithm of B the height of the eye; then will half the sum be the logarithm of the tangent BA, ID which is nearly the same with the arc D. A., the distance required. Rule 2. To half the loga- C rith of the height of the eye, add 3,8104601, and the sum . . - will be the logarithm of the distance required in feet, nearly. Example.—Let the height of the eye be 100 feet. Required the distance of the visible horizon 2 By Rule 1. - Diameter of the earth + 100 = 41,775,460 feet log. 7.6209213 Height of the eye. . . . . . . . . . E 100 feet log. 2:0000000 sºmºmºsºmsºmºs 2) 962092.13 Distance required ......... = 64633.9 feet log. 4.8104608 * By Rule 2. Constant logarithm - 3.8104601 Half the logarithm of 100 - 1:0000000 *º Distance required = 646339 = 4.8104601 HEIR, in Law, the person who succeeds another, by descent, ‘to lands, tenements, or hereditaments. . Hei R, Apparent, is a person so called, in the lifetime of his ancestor, at whose death he is heir at law. See APPARENT. Hei R Presumptive, is one who, if the ancestor should die immediately, would, in the present circumstances of things, be heir : but whose right may be defeated by some nearer heir being born. - Hei R Looms, in Law, are such goods and personal chattels, as, contrary to the nature of chattels, shall go by special custom to the heir. t HELIACAL, as applied to the rising of a star, planet, &c. denotes its emerging out of the sun’s rays, in which it was before hid. When applied to the setting of a star, it denotes the entering or immerging into the sun's rays, and thus becom- ing lost in the lustre of his beams. A star rises heliacally when, after it has been in conjunction with the sun, and on that account invisible, it gets at such a distance from the sun as to be seen in the morning before the rising of that luminary. - . HELIOCENTRIC PLAce of A PLANET, is that place in the ecliptic in which the planet would appear if viewed from the centre of the sun; and consequently the heliocentric place coincides with the longitude of a planet, as viewed from the same centre. HelioceNTRic Latitude of a Planet, is the inclination of the line drawn between the centre of the sun and the centre of a planet, to the plane of the ecliptic. r HELIOCOMETES, CoMet of THE SUN, is used to denote a phenomenon which sometimes attends the setting of the sum. It is thus denominated by Sturmius, who had observed it, because it seems to make a comet of that luminary, having the appearance of a large tail or column of light which follows the sun at his setting, much in the same manner as the tail of a COmet. HELIOMETER, or AstroMeter, is the name given by Bouguer to an instrument which he invented for measuring with particular exactness the diameter of the sun, moon, and planets. This instrument is merely a telescope, consisting of two object glasses, of equal focal distance, placed by the side of each other, so that the same eye-glass serves for both. The tube of this instrument is of a conical form, larger at the upper end, which receives the two object-glasses, than at the lower, which is furnished with an eye-glass and micrometer. Hence two distinct images of an object are formed in the focus of the eye-glass, the distance of which depending upon that of the two object-glasses from one another, may be measured with the greatest accuracy. HELIOSCOPE, a telescope fitted for viewing the sun with- out hurting the eyes. . HELIX, in Geometry, the same with Spiral, which see. HELIx, in Natural History, the Snail, a genus of the vermes testacea class and order. It is used in many parts of Europe as food, particularly at Rome during the weeks of Lent, where they are fattened, and grow to a very large size. H. Hortensis, garden-snail, has an imperforate shell, globular, pale, with broad interrupted brown bands; this species inhabits the gar- dens and orchards in most parts of Europe; it abounds with a viscid slimy juice, which it readily gives out by boiling in milk and water, so as to render them thick and glutinous, and the compound, especially with milk, is reckoned efficacious in con- sumptive cases. Snails are very destructive to wall fruit: lime and ashes sprinkled on the ground will keep them away, and destroy the young brood. Fruit, already bitten, should not be taken off the tree, for they will not touch the other till they have wholly eaten this, if left for them. The eyes of snails are lodged in their horns, one at the end of each horn, which they can retract at pleasure. Cutting off a snail’s head, a little stone appears, which is supposed to be a good diuretic, and excellent in all nephritic disorders. S HELLEBORUS, in Botany, English hellebore, a genus of the polyandria polygynia class and order. Natural order of Mul- tisiliquae, Renunculaceae, Jussieu. There are seven species. The root is tuberous. By distillation an extremely poisonous oil is obtained from it. HELM, a long and flat piece of timber, or an assemblage of several pieces, suspended down the hind part of a ship's stern- post, where it turns upon a kind of hinges to the right or left, serving to direct the course of a vessel, as the tail of a fish guides the body. The helm is usually composed of three parts, viz. the rudder, the tiller, and the wheel, except in small vessels, where the wheel is unnecessary. The rudder becomes gradually broader in proportion to its distance from the top, or its depth under water; the back or inner part of it, which joins the stern-post, is diminished into the form of a wedge, through- out its whole length, so as that it may be more easily turned . from one side to the other when it makes an obtuse angle with the keel. For a description of the hinges which support it, see the articles Goog ING's and PINtles. The length and thick- ness of the rudder is nearly equal to that of the stern-post. The tiller is a long bar of timber, fixed horizontally in the upper end of the rudder, within the vessel; the movements of the tiller to the right and left accordingly direct the efforts of the rudder to the government of the ship's course, as she advances; which is called steering. The operations of the tiller are guided and assisted by a sort of tackle, communicat- ing with the ship's side, called the tiller-rope, which is usually composed of untarred rope yarns, for the purpose of travers- ing more readily through the blocks or pulleys. In order to facilitate the management of the helm, the tiller-rope, in all large vessels, is wound about a wheel, which acts upon it with the powers of a windlass; the rope employed in this service 448 H E L .H E L DICTIONARY OF MECHANICAL SCIENCE. being conveyed from the fore-end of the tiller to a single block on each side of the ship, forms a communication with the wheel, by means of two blocks suspended near the mizzen- mast, and two holes immediately above, leading up to the wheel, which is fixed upon an axis on the quarter-deck almost perpendicularly over the fore-end of the tiller. Five turns of the rope are usually wound about the barrel of the wheel, and when the helm is a-midship, the middle turn is mailed to the top of the barrel with a mark, by which the helmsman readily discovers the situation of the helm ; the spokes of the wheel generally reach about eight inches beyond the rim or circum- ference, serving as handles to the person who steers the ves- sel: as the effect of a lever increases in proportion to the length of its arm, it is evident that the power of the helmsman to turn the wheel will be increased according to the length of the spokes beyond the circumference of the barrel: so that if the helmsman employs a force of thirty pounds, it will produce an effect of from ninety to one hundred and twenty pounds upon the tiller, (the barrel being # or 4 of the radius of the spokes,) which again forming the long end of a lever 10 or 15 times the length of its shorter arm, the force of the rudder will by consequence be from 10 times 90 to 15 times 120; or from '900 to 1800 pounds. When the helm operates by itself, the centre of rotation of the ship and her movements, are deter- mined by estimating the force of the rudder by the square of the ship’s velocity. l When the helm, instead of lying in a right line with the keel, is turned to one side or the other, as in B D, in the figure, it receives an immediate shock from the water, which glides along the ship's bottom in running aft from A to B; and this *.. * * * s * fluid pushes it towards the opposite side, whilst it is retained in this position: so that the stern, to which the rudder is con- fined, receives the same impression, and accordingly turns from B to b about some point e, whilst the head of the ship passes from A to a. It must be observed, that the current of water falls upon the rudder obliquely, and only strikes it with that part of its motion, which acts according to the sine of inci- dence, pushing it in the direction of N P, with a force which not only depends on the velocity of the ship's course, by which this current of water is produced, but also upon the extent of the sine of incidence. This force is by consequence composed of the square of the velocity with which the ship advances, and the square of the sine of incidence, which will necessarily be greater or smaller according to circumstances; so that if the vessel runs three or four times more swiftly, the absolute shock of the water upon the rudder will be mine or sixteen times stronger under the same incidence: and if the incidence is increased, it will yet be augmented in a greater proportion, begause the square of the sine of incidence is more enlarged. This impression, or, what is the same thing, the power of the helm, is always very feeble, when compared with the weight of the vessel ; but as it operates with the force of a long lever, its efforts to turn the ship are extremely advantageous. For the helm being applied to a great distance from the centre of gra- vity G, or from the point about which the vessel turns horizon- tally, if the direction P N of the impression of the water upon the rudder be prolonged, it is evident that it will pass perpen- dicularly to R, widely distant from the centre of gravity G : thus the absolute effort of the water is very powerful. It is not therefore surprising, that this machine impresses the ship with a considerable circular movement by pushing the stern from B to b, and the head from A to a ; and even much farther while she sails with rapidity, because the effect of the helm always keeps pace with the velocity with which the vessel advances. Amongst the several angles that the rudder makes with the keel, there is always one position more favourable than any of the others, as it more readily produces the desired effect of turning the ship, in order to change her course. To ascertain this, it must be considered, that if the obliquity of the rudder with the keel is greater than the obtuse angle A BD, so as to diminish that angle, the action of the water upon the rudder will increase, and at the same time oppose the course of the ship in a greater degree ; because the angle of incidence will be more open, so as to present a greater surface to the shock of the water, by opposing its passage more perpendicularly. But at that time the direction N P of the effort of the helm upon the ship will pass with a smaller distance from the centre of gravity G towards R, and less approach the perpendicular N L, according to which it is absolutely necessary that the power applied should act with a greater effect to turn the vessel. Thus it is evident that if the obtuse angle A B D is too much enclosed, the greatest impulse of the water will not counterba- lance the loss sustained by the distance of the direction NP from N L, or by the great obliquity which is given to the same direction N P of the absolute effort of the helm with the keel A. B. If, on the centrary, the angle A B D is too much opened, the di- rection N P of the force of the action of the helm will become more advantageous to turn the vessel, because it will approach nearer the perpendicular N L; so that the line prolonged from N P will increase the line G. R., by removing R to a greater dis- tance from the centre of gravity G, but then the helm will receive the impression of the water too obliquely, for the angle of incidence will be more acute ; so that it will only present a small portion of its breadth to the shock of the water, and by consequence will only receive a feeble effort. By this principle it is easy to conceive, that the greatest distance G. R. from the centre of gravity G, is not sufficient to repair the diminution of force occasioned by the too great obliquity of the shock of the water. Hence we may conclude, that when the water either strikes the helm too directly, or too obliquely, it loses a great deal of the effect it ought to produce. Between the two ex- tremes there is therefore a mean position, which is the most favourable to its operations. The diagonal N P of the rectangle IL represents the absolute | direction of the effort of the water upon the helm. N I ex- presses the portion of this effort which is opposed to the ship's head-way, or which pushes her astern, in a direction parallel to the keel. It is easily perceived that this part N I of the whole power of the helm contributes but little to the turn of the vessel; for, if I N is prolonged, it appears that its direction approaches to a very small distance G W from the centre of gravity G ; and that the arm of the lever B N-G V, to which the force is applied, is not in the whole more than equal to half the breadth of the rudder: but the relative force N L, which acts perpendicular to the keel, is extremely different. If the first N I is almost useless, and even pernicious, by retarding the velocity; the second NL is capable of a very great effect, because it operates at a considerable distance from the centre of gravity G of the ship, and acts upon the arm of a lever G. E., which is very long. Thus it appears, that between the effects NL and N I, which result from the absolute effort NP, there is one which always opposes the ship's course, and contributes little to her motion of turning; whilst the other produces only this movement of rotation, without operating to retard her velocity. Geometricians have determined the most advantageous angle made by the helm with the line prolonged from the keel, and fixed it at 54° 44', presuming that the ship is as narrow at her floating-line, or at the line described by the surface of the water round her bottom, as at the keel. But as this supposition is absolutely false, in as much as all vessels augment their breadth from the keel upward to the extreme breadth, where the float- ing-line or the highest water-line is terminated ; it follows that this angle is too large by a certain number of degrees. For the H E L H E M 449 DICTIONARY OF MECHANICAL SCIENCE. tºp ſ rudder is impressed by the water, at the height of the floating- line, more directly than at the keel, because the fluid exactly follows the horizontal outlines of the bottom; so,that a parti- cular position of the helm might be supposed necessary for each different incidence which it encounters from the keel up- wards. But as a middle position may be taken between all these points, it will be sufficient to consider the angle formed by the sides of the ship, and her axis or the middle line of her length, at the surface of the water, in order to determine after- wards the mean point, and the mean angle of incidence. It is evident that the angle 54° 44' is too open, and very un- favourable to the ship's head-way, because the water acts upon the rudder there with too great a sine of incidence, as being equal to that of the angle which it makes with the line prolonged from the keel below: but above the shock of the water is almost perpendicular to the rudder, because of the breadth of the bottom, as we have already remarked. If then the rudder is only opposed to the fluid, by making an angle of 45° with the line prolonged from the keel, the impression, by becoming weaker, will be less opposed to the ship’s head- way, and the direction N P of the absolute effort of the water upon the helm drawing nearer to the lateral perpendicular, will be placed more advantageously, for the reasons above mentioned. On the other hand, experience daily testifies, that a ship steers well when the rudder makes the angle D B equal to 35° only. 's It has been already remarked, that the effect of moving the wheel to govern the helm increases in proportion to the length of the spokes; and so great is the power of the wheel, that if the helmsman employs a force upon its spokes equivalent to 30 pounds, it will produce an effect of 90 or 120 pounds upon the tiller. On the contrary, the action of the water is collected into the middle of the breadth of the rudder, which is very narrow in comparison with the length of the tiller; so the effort of the water is very little removed from the fulcrum B upon which it turns; whereas the tiller forms the arm a lever 10 or 15 times longer, which also increases the power of the helmsman in the same proportion that the tiller bears to the lever, upon which the impulse of the water is directed. This force then is by con- sequence 10 or 15 times stronger; and the effort of 30 pounds, which at first gave the helmsman a power equal to 90 or 120 pounds, becomes accumulated to one of 900 or 1800 pounds upon the rudder. This advantage then arises from the short- ness of the lever upon which the action of the water is impress- ed, and the great comparative length of the tiller, or lever, by which the rudder is governed; together with the additional power of the wheel that directs the movements of the tiller, and still farther accumulates the power of the helmsman over it. . Such a demonstration ought to remove the surprise with which the prodigious effect of the helm is sometimes considered from an inattention to its mechanism; for we need only to ob- serve the pressure of the water, which acts at a great distance from the centre of gravity G, about which the ship is supposed to turn, and we shall easily perceive the difference there is be- tween the effort of the water against the helmsman, and the effect of the same impulse against the vessel. With regard to the person who steers; the water acts only with the arm of a very short lever N B, of which B is the fulcrum : on the con- trary, with regard to the ship, the force of the water is impress- ed in the direction N P, which passes to a great distance from G, and acts upon a very long lever E G, which renders the action of the rudder extremely powerful in turning the vessel; so that, in a large ship, the rudder receives a shock from the water of 2700 or 2800 pounds, which is frequently the case when she sails at the rate of three or four leagues by the hour; and this force being applied in E, perhaps 100 or 110 feet dis- tant from the centre of gravity G, will operate upon the ship, to turn her about, with 270,000 or 308,000 pounds; whilst, in the latter case, the helmsman acts with an effort which exceeds not 30 pounds upon the spokes of the wheel. After what has been said of the helm, it is easy to judge, that the more a ships increases her velocity with regard to the sea, the more powerful will be the effect of the rudder; be- cause it acts against the water with a force, which increases as the square of the swiftness of the fluid, whether the ship ad- vances or retreats, or, in other words, whether she has head- 47, | way or stern-way; with this distinction, that in these two cir- cumstances the effects will be contrary. For if the vessel retreats, or moves astern, the helm will be impressed from I to N; and instead of being pushed, according to NP, it will re- ceive the effort of the water from N towards R; so that the stern will be transported to the same movement, and the hea turned in a contrary direction. +. - HELMET, an ancient defensive armour, worn by horsemen both in war and in tournaments, which covered both the head and face, leaving only an aperture in the front secured by bars which was called the visor. It is still used in heraldry by way of crest over the shield or coat of arms, to express the differ- ent degrees of nobility by the different manner in which it is borne. Thus, a helmet in profile is given to gentlemen and esquires; to a knight the helmet standing forward and the beaver a little open; the helmet in profile and open, with bars, belongs to all noblemen under the degree of a duke; and the helmet forward and open, with many bars, is assigned to kings, princes, and dukes. HEMISPHERE, in Geometry, is one-half of a globe or sphere, formed by a plane passing through its centre. . He MISPHERE, in Astronomy, is particularly used to denote one-half of the sphere, as separated by the plane of the equa- tor; that situated towards the north pole being called the northern, and the other the southern hemisphere. The horizon also divides the sphere into two hemispheres, the lower and the upper; the latter being that half which has the zenith for its vertex, the former having the nadir in its vertex. We have, in this work, given two hemispheres of the celes- tial regions, exhibiting all the stars and constellations exactly as they appear in nature: the whole of the stars having their right ascension and declination computed for the present century. HEMISPH ERE is also used for a map or projection of half the terrestrial globe, or half the celestial sphere on a plane. These are also frequently called Planispheres. HEMISTICH, in poetry, denotes half a verse, or a verse not completed. HEMP. See CANNABIs. The cannabis sativa, or hemp plant, is cultivated on account of its external filaments. which constitute the hemp used for cordage, canvass, cloth, &c. and the seeds abound with oil. The operations of harling, watering, breaking, swingling, and heckling, hemp are very much like those practised in the dressing of flax.—The hemp imported into this country chiefly comes from Russia. The best hemp should be clean, soft, tender, of long staple, and a sound palish-yellow colour, neither green nor red. Many experiments have been made upon the relative strength and utility of the nettle, the hop, the aloe, the yucca, the barks of the mulberry and bread-fruit tree, and many other vegetable fibres for the production of thread, cloth, and paper, yet is the hemp, the flax, and the cotton superior to them all, not only on account of their abundance and easy culture, but from the very superior strength and fineness of their fibres under all changes of circumstance. - The hemp being the larger and stronger plant, yields the longest, coarsest, and strongest fibres, and is usually employed in forming all kinds of ropes and cordage, coarse cloth and sacking; notwithstanding which, if properly dressed and ma- naged, a white linen may be produced from it very little in- ferior in texture to that of flax, and certainly superior in durability. Flax, on the contrary, being a more tender and delicate plant, produces a finer fibre by ordinary treatment, and is used for the finer fabrics of thread, linen, and cambric. The flax plant (Linum of Linnaeus) is an annual, requiring to be sown with seeds of the last year's product, from the second week in March to the middle of April. It prefers a free open loam, which is neither subject to too much wet or drought; is certain of producing a good crop on new ground, and will generally thrive on any soil which is proper for bar- ley or oats. It remains in the ground till the end of July, or middle of August, when it ripens, and is fit for pulling,” (un- less it should, from circumstances, be desirable to keep it for * This should be done soon after the bloom falls off, when the stalk begins to turn yellow, and before the leaves fall off. 5 Y A50 H E M H E M. DTCTION ARY OF , MECHANICAL SCIENCE, seed only,) and may be succeeded by a crop of wheat or tur- hips, for which it is an excellent preparation. It may also be sown to advantage with clover seeds, which will then succeed it as an after-crop. Hemp (Cannabis sativa) is a much more rank and coarse plant, growing from six to sixteen feet in height, and is more or less common in all countries. It is, however, chiefly cultivated in the northern parts of Europe, whence it is largely imported into England. It thrives well in England; and English hemp, when properly manufactured, is found more compact, strong, and durable than that of Russia. It should be sown about the same time as flax, in a deep, rich, and moist soil, on which account the Isle of Ely and the fems of Lincolnshire are particularly favourable to its growth. Like flax, when sufficiently ripe, it is not cut, but pulled up root and all, on which account both these plants leave the soil parti- cularly clean. - The fibre is situated between the interior wood and exterior bark of each stalk, and was till lately, always obtained by an aqueous decomposition, or by rotting away the wood and exte- rior bark by exposure to moisture, since the fibre itself (though, no doubt, somewhat injured by the process) has sufficient strength and durability to withstand it in a great measure. The process of rotting away the woody from the fibrous parts of plants, though one of extreme antiquity, has proved ex- tremely detrimental to the health, not only of the inhabitants, but injurious to the cattle, of those countries in which it is car- ried on to a considerable degree. It becomes the source of many pestilential diseases, among which perhaps the Malaria, so prevalent in the vicinity of Rome and Naples, may be numbered; besides which, since flax and hemp ripen about the month of August, and require to be submitted to this process as soon as they are taken from the ground, or at least before they dry, the farmer's attention becomes necessary to them when his time is most valuable and can least be spared, namely, in the time of, or immediately antecedent to, his corn harvest. The product to be expected from the growth of flax is of two kinds, viz. The seed for oil and sowing, and the fibre for spin- ning. These are nearly equal in value, and it has been usual for cultivators to govern their operations by the kind of crop which is produced; thus, if it grows short and branchy, the seed will be more valuable than the flax, which consequently should not be disturbed until that seed is perfectly ripe; while, on the contrary, if it proves tall, and has not fallen, the seed (although not ripe) is excellent food for cattle, and must be threshed out as perfectly as possible, and the remainder sacri- ficed to the fibre. A very good machine for threshing out flax in this state, was invented by Mr. Cleall, and will be found described in the Transactions of the Society for the Encourage- ment of Arts and Sciences, London, vol. xxv, p. 143. The operation of rotting, or, as it is generally called, Water Retting Flax and Hemp, is one of considerable nicety, and hazard to the cultivator, on which account it has, in all proba- bility, proved a much greater barrier to the cultivation of these useful plants in England, than the alleged exhaustion of soil, or any other cause ; for its perfection, and the period when it should cease, depend on several fortuitous circum- stances, which may dispose the woody matter of the stem to decompose with greater or less facility. Thus it will be in- fluenced by the strength and vigour of the plant, the moisture or dryness of the season, the temperature of the air during the process, as well as the soil from which the plant is pro- duced. If the operation is carried too far, not only the woody matter, but the fibre also, will be destroyed or injured, and if not far enough, it has generally been thought that the flax will not dress: and thus, after a good crop has been produced, it may be much injured, if not spoiled, in the incipient stage of its manufacture. ' The steeping or watering of flax is most commonly per- formed in artificial ponds or canals, excavated by the sides of rivers, and generally about 40 feet long, 6 feet wide, and 4 deep, a sufficient size to admit the produce of an acre of land at once. Sluices are so disposed, that the contained water may at any time be let off, and a fresh quantity of water, which should be soft, admitted. These canals should be ex- posed to the sun, which assists the decomposition. The fresh- gathered flax being tied in bundles or handfuls, is carefully placed in these reservoirs, the superior bundles: causing those which were first deposited to sink; and in this way each reservoir is filled, but not to such a degree as to force any part of the flax to touch the bottom; and when filled, the whole surface is covered with close hurdles or boards, and sufficiently loaded with stones to cause every part of the ſlax to be under the surface of the water. In this state it is left, and occa- Sioually examined, to ascertain how far the process of decom- position is completed, which will generally be within a fortnight. The bundles of flax, which have by this time become very tender and difficult to handle, are now to be taken out on boards or trays, and removed on to the nearest short grass or heath, where they are regularly disposed in rows to loose their moisture, and in which situation they receive an additional preparation from the evening dews and occasional showers completing the decomposition, and at the same time washing away the slime and mucilage with which they are mixed. This last exposure is called dew-retting, and continues, according to the state of the atmosphere, for four or five weeks, or until the flax is as dry as it can be got, of a clear good colour, and all the woody matter which remains is perfectly brittle. The fibre will still retain most of its original tenacity, if the operation has been carefully and skilfully con- ducted. It is then carried away, like hay, on a fine dry day, and deposited in barns, being now ready for the next process, called breaking and dressing. So soon as a reservoir is emptied as above described, its water is let off, of course in a very putrid and unwholesome state. The basin is washed out; a new quantity of water is admitted, which is now ready to receive a fresh charge of flax. The rivers, by receiving this water, particularly if hemp has been steeped in it, become contaminated ; their fish are killed ; the cattle refuse to drink it; and the atmosphere around is filled with noxious vapours, most detrimental to the health of the inhabitants. º - The breaking of flax is the separation of what is technically called the Boon, or woody matter, from the Harle, or useful fibre; and this may be effected in a variety of ways. It is done in mills by machinery, and by hand, and in almost all cases is very effectually performed by a set of blunt iron teeth or breakers, fixed upon one piece of wood, and met by another similar set of teeth fixed to a moveable piece, which is worked by the one hand, while the flax in handfuls is introduced between these teeth in various directions with the other hand. This breaks and knocks off the greater part of the wood in small fragments, called chaff, and the operation is completed by scutching or beating the flax against a smooth post called a scutching post, and also beating it with an instrument some- what resembling a curry-comb, and called a hand scutch, by which the few remaining fragments of wood or boon are taken away, and nothing but the long fibre remains, which is now to be hackled, or drawn by the hand over a species of comb, having a great number of very sharp long and perpendi- cular steel points upon it, by which any remaining boon and the short fibres or tow are removed, and the long fibres which remain are regularly disposed, and ready to pass into the hands of the spinner. Flax and hemp have obtained the character of being very impoverishing crops to the land which bears them, and very deservedly so. For while every other crop makes a return to the land, either of its roots or branches to decay, and forms manure, or becomes matter of animal food; these make no such return, at least to their own land. . . . - But although the above methods are still practised on the con- tinent, it has been discovered, that the process of steeping and dew-retting, as applied to flax and hemp, is wholly unnecessary; and that these vegetables will not only dress, but will produce an equal, if not greater quantity of more durable and ser- viceable fibre, when treated in the dry way, than when exposed to the tedious, difficult, and precarious process which has been above described; and it is to be lamented, that a discovery of so much national importance, made in this country, should not hitherto have been recorded and described in any of her jour- mals or archives of science. - This discovery was first given to the world by Jas. Lee, Esq. formerly of Old Ford, in Essex, and latterly of Merton Abbey H E M H E M DICTIONARY OF MECHANICAL SCIENCE. 451 Flax Mills, he having obtained a patent for his process in 1812, under the singular protection of a special act of Parliament, which permitted the specification of that patent invention to remain sealed up for seven years, contrary to the general prac. tice in such cases. . . #, - Among the more valuable concomitants of this discovery, are the circumstances of the noxious vapours and unhealthy employment attendant upon the former process of steeping flax being removed, as well as the supply of an abundance of in-door winter employment, being produced in the breaking and preparation of flax for spinning, when it has been thus husbanded, and which may be resorted to at all convenient times, when the farming labourers and servants are shut out from other work by the inclemency of seasons or other causes; and thus it is presumed a new source of active and lucrative employment is held out to the British farmer, by the adoption of which, he may in a few years be in the receipt of that im- mense capital which is now paid to foreign countries upon the importation of flax and hemp. te The machinery to be used for breaking and manufacturing the flax and hemp prepared by his dry method, so far as it has come before the public in the use of Mr. Lee's patent process, does not appear to have fully answered his purpose ; for we find that a few years since he obtained another patent for other machinery and processes not included in the first, and of which the specification is not protected by the same secrecy of enrolment. He thus appears to have been made fully satisfied, by experience, of the incapacity of his first machines to produce much work, and therefore now abandons them, and performs his whole operation by means of a series of small iron fluted rollers, combined by pairs in frame-work, working in each other's teeth or projections, (as shewn in the plate of Mills,) and made to press or bear upon each other in any assigned degree, and so as to admit larger || or smaller charges of flax between them, by means of levers and weights; and although the application of such fluted rol- Jers to the breaking of flax and hemp has long been common, particularly in Scotland, yet Mr. Lee's arrangement of them is novel, ingenious, and perfectly answers the purpose. Instead of using one or two pair, as usual, he proposes to dispose a number of single pairs of rollers by the side of each other, having them all kept in motion at once by a water wheel or other prime mover; and instead of passing the flax through them in its natural straight form, it is entered between them, and as soon as the ends appear, and come out on the opposite side of the rollers, those ends, which are following are intermixed or overlayed, or, as it is technically called, tailed on to the first, so as to form a circular hoop or skein of flax, which having, as it were, no end, will continue to revolve between the rollers for any length of time. The importance of a cheap, effective, and expeditious mode of breaking and preparing raw flax and hemp, is such, that it cannot be a matter of surprise, that many ingenious mecha- nics should have turned their attention to this subject. Several models of machines for this purpose have been invented, parti- cularly by Bond and Durand, which will be found described in the Transactions of the Society for the Encouragement of Arts, Manufactures, and Commerce, vol. 25, p. 152, and vol. 31, p. 269; and especially those of Messrs. Hill and Bundy, of Camden Town, London, for which Mr. Bundy obtained a patent for Great Britain and France, and which, from the novelty of their actions and motions, and the very speedy and efficacious manner in which they perform their work, deserve to be particularly noticed. These machines are, a Breaker and a Rubber.—The first being for the purpose of separating the harle from the boon, as usual, but by a new process: the latter for rubbing and sub- dividing the fibres so as to produce it in its greatest state of perfection, and finally cleansing it before it goes to the hack- ler. The breaking machine will be first described, as it is to be first used, and it will appear, that although it consists chiefly of fluted or toothed cylinders, yet it varies from all other machines for the same purpose, which have preceded it, by the inequality of the depth of its teeth, the play or space which exists between one tooth and another, and in the reciprocating motion of the cylinders combined with their progressive motion, instead of its being progressive only, as in all former cases; by these means the happiest effects are produced. The simple manner, in which this complex motion is brought about, reflects the highest credit on the mechanical skill of Mr. Bundy, the inventor, not only of these machines, but of many others of equal ingenuity. g 4- Fig. 1. e *. Žº g º ſº º it'ſ º G. º § º i. º § * - º * * º ; >. |º]}} liº º #|I. ºy Eº İğ Fig. 1 represents a side view of the breaking machine on a scale of about half an inch to a foot. The framing, A, is of timber, which serves to support the five breaking cylinders marked C c DEE, turning on pivots. C D and c move in brass bearings, fixed upon the boards or supports B, on the two opposite sides of the machine, while E E merely lay above and between CD and D c, and are drawn down to these by two rods, as seen at FF. The lower ends of these are joined by a connecting bar, and another rod proceeds downwards, its lower end being fixed by a double adjusting nut G, near the pin or fulcrum H, of the lever or presser, H, I, which is loaded with a weight J. There is a similar lever on each side of the | machine, to bear down the four ends or pivots of the two rollers E E, and the ends of these levers nearest I, are united with a cross bar, by means of which one weight, J, acts on them both, and is made to press equally by an adjusting nut and screw, on each side, like G. K L is a lever placed under the machine, one end of which is attached to the weight J, in such manner that by pressing down its end L, J is raised, and all pressure is instantly prevented between the superior cylinders EE, and those under them at CD c, for stopping the operation of the machine at any time. The breaking cylinders are about eigh- teen or twenty inches in length, and are made of beech or any hard wood, and are all similar to each other in dimensions, and in having breakers which act also as teeth, extending like pro- jecting plates their whole length parallel to the axis. These breakers or teeth are formed of thin hoop-iron, let about half its width into saw cuts in the cylinders into which they are driven, and they are retained in their places by iron hoops put on to each end of the cylinders; they are about half an inch asunder, their external edges are well rounded, so as not to cut the flax, and they are alternately long and short; the long or deep teeth projecting about three-quarters of an inch from the cylinder, while the short ones are about half that length. In placing the lower breaking cylinders in their places, care must be taken that they do not touch each other, since their teeth are only to connect through the medium of the two upper rollers which, press upon them. The axis of the roller D is longer than the others, and extends on both sides beyond the frame and upon each end of it is fixed a cast-iron wheel, by which motion is to be given to this cylinder, and through this to all the others. Both the wheels are of the same diameter, but one is a ratchet wheel, as will be seen in the last figure, while 452 H E M H E M DICTIONARY OF MECHANICAL SCIENCE. that on the opposite side is a spur or common toothed wheel, as will be seen in fig. 2, which represents such parts of the machine on the opposite side as are essential to its motion, and the same letters of reference are used in both figures to denote similar parts. - Fig. 2. º * " * sº § ºs.) d º N. *'''S * … g º º º Sºº' ſº is . . ºf: º ºlº | \, \ºllºilºšlj|| t ºriº | S. ſº l l | # : º E" | The first motion is given to this machine from the iron spindle O, fig. 1, which may be turned by a handle, or by a band and rigger, as at P. It may also be connected with a pair of spur wheels and a fly, as shewn in fig. 1, to assist its motion. On each end of the lower spindle, if two are used, there is a crank, as at Q, attached to a coffnecting rod V, the opposite end of which in fig. 1, is attached to a pall or lever turning on a centre S, so that when O, or O O, is turned, the end of this lever will describe a portion of a circle, shewn by the dotted line TA, and will engage with the ratchet teeth of the wheel M, and carry it partly round ; while on the other side of the machine, shewn in fig. 2, the connecting rod V passes from the crank of O to a toothed segment U, the teeth of which work into the teeth of the spur wheel N, fixed upon the opposite gudgeon of the breaking cylinder D. The con- necting rod on this side of the machine must be so adjusted in length, that in its motion outwards the end tooth of U, next to A, must be withdrawn out of the teeth of the wheel N, but that when it moves in a contrary direction, or from T towards A, it must move completely in the teeth of the wheel, and not leave them, and of course N at this time is incapable of any other motion, but what the segment U also has. . The connecting rod Q V, in fig. 1, must also be so adjusted in length to the pall or gathering tooth S, as to make it continue to act upon its wheel M, for the space of one tooth of N in fig. 2, after the segment U has been withdrawn from its wheel, N; and thus, although the motion of U would produce a back- ward and forward motion of its corresponding wheel N, and the breaking cylinder D, and consequently of all the other cylinders, yet by the after action of S upon M, the roller D and its wheel N are made to advance gradually by the space of one tooth of N for every revolution of O ; and thus a slow but regular progressive motion of the cylinders is obtained at the same time that the vibratory or oscillating motion is going on. The flax is fed or supplied by placing it in handfuls on the feeding trough Z, and pressing it gently between the rollers, C and E, and it is delivered out from between the rollers E and c, at the end of the machine next to L, in a sufficiently clean and divided state to enter the rubbing machine, which will be next described. The superiority of this machine over common fluted rollers needs no comment, since the distance between the teeth and the shake which is produced by the alternating motion of the cylinders exactly gives that action which is best suited to break off and disengage the bark and woody matter, which, when dry, is quite brittle, and falls to the bottom of the machine. Once passing the rollers is in general sufficient for either flax or hemp stalks, but the work is ren- dered more perfect by a second passage through them, which does not at all injure the fibre. . . . - The rubbing machine, which is to be used immediately after the above breaking process, was suggested to the inventor from the beneficial effect which he found produced on broken flax by rubbing it between the hands in the same manner that linen is rubbed while washing, and which not only cleanses it of the small fragments of wood and bark which adhere to it, but likewise opens and subdivides the fibres, so as to make them produce the finest thread. The machine and operation are altogether new as applied to flax and hemp, and it is confidently hoped considerable benefit may arise from their use. Fig. 3 represents a side view, or rather section of this machine, drawn on a scale of one inch to a foot. sº sº º | | |#|| +. º |. º #|º Cl sº ºrrºsè cº iºn W º ºl In this, a is the wooden frame for supporting the machine ; b, the bearers for the three rollers c de, disposed as in the break- ing machine; but in this case, they are only for the purpose of drawing or leading the flax through the machine, (the break- ing being presumed to have been already done by the last. described, or any other process;) they must be fluted or grooved, or may be made in the same manner as the breaking cylinders, but with the teeth of equal length, much shorter, and of a finer gauge or pitch; f is a rigger or pulley to which a rapid circular motion is to be given ; it is hung on a shaft or spindle turning in brass bearings, and fixed to the frame a ; on the end h of this spindle is formed an endless screw or worm, which turns a small wheel i fixed upon the lower end of an iron spindle k turning in bearings, and leading by a bevil pinion, at its upper end to the face wheel n, which is fixed on to. one of the gudgeons of the fluted or toothed roller e, so that whenever the rigger f is turned, even with a rapid motion, a very slow motion will be communicated to the rollers c de The most essential part of this machine consists of the rubber boards op q r, which are placed at the front of the machine are seven in number in the print, but may be more or less, and are about an inch in thickness; they may be made of beech, oak, or any moderately hard wood. Their edges or sections can only be seen in this representation, but their length may be from eight inches to a foot or more. The board o is firmly fixed to the top of the framing a, and is without motion, while those marked ppp are supported upon the two strong cylindrical iron pins s, which are firmly screwed H E M H E R. 453 DICTIONARY OF MECHANICAL SCIENCE. into the frame a, and pass through holes which fit them in the boards ppp, so that these last can be moved to a greater or less distance from each other, but are incapable of up and down motion. The intermediate boards q q q are so much shorter as to pass between the iron pins s and admit of an up and down motion between ppp ; for this purpose, they are all connected together by an iron link or staple ar, fixed upon the top of the connecting rod u, the lower end of which works upon a crank in the middle of the first spindle upon which the rigger f is placed, so that in every revolution of f the moveable boards qq q are driven upwards and downwards between the more stationary boards p pp, and the one which is fixed at 0. The whole of the boards are drawn towards o by means of a rod on each of their sides passing through ppp and o, and acted upon at t by weights or spiral wire springs, and the whole of the boards are perforated with a slit or mouth from four to six inches long, (according to their width) and about a quarter of an inch wide, placed near their tops at an equal distance from the top of each, and nicely rounded off on all its edges. The conse- quence will be, that whenever the ‘crank is in an horizontal situation, all these slits will coincide, but when the crank is down, as in the figure, the slits in q q.4 (which slits are seen only in section) will be below those in ppp and o, while when the crank is up they will be elevated above them; and thus it will easily be perceived, that if flax, or any other flexible mate- rial, is passed through the slits in the boards when they do coincide, and then conducted between the toothed rollers, that while these draw it slowly on through the machine, the boards, pp, q q., &c. by their rapid up and down motion, will effectually rub it, and cleanse it from any extraneous matter which may adhere to it, as well as open the fibres; and for the better regu- lation of this operation, v is a treadle or lever near the foot of the attendant, by pressing on which, the weight w, which depresses the top roller d, will be raised, in consequence of which the rollers will cease to draw, although the rubbing still continues, so that its velocity in passing the machine may be correctly regulated at the will of the superintendant.* The average crop which has been produced in England from sowing three bushels of flax or lint seed on an acre of land, is 2% tons of flax stem, which, when broken and prepared, yields from 10 to 13 cwt. of harle, or ſlax fit for hackling, and the boon or woody matter which falls through the machine, will yield from 90 to 100 bushels of chaſſ from the seed, and is fit for provender for horses or cattle, and from 35 to 40 cwt. of chaſt from the stem, making a valuable manure, while from 10 to 14 bushels of seed may, in almost all cases, be procured from the same quantity. The operation of hackling, which succeeds that of breaking, was here minutely described and shewn, and by this the average of 12 cwt. of harle, produced by an acre of land, becomes diminished down to about from 450 to 380 lbs. of fine long flax, fit for spinning the best mate- rials, being but little more than ºrth of the gross produce ; not- withstanding which, the value of the seed, the chaff, and the tow, which is the refuse of the hackling process, are said to amply compensate for this apparent loss. Spinning is the operation which succeeds to hackling, and the advantages arising from this union, by twisting the fibres together, was detailed, as well as the mechanical action, by which strength and continuity of length are obtained by the lateral friction of one ſibre against another. The yarns, when completed, are wound into skeins of 300 yards each in length, by means of counting reels, which strike upon a bell, or otherwise indicate when this quantity is com- plete, and such skeins are called leas. From the number of leas which a pound of ſlax will produce, its denomination and value is computed. Thus yarn No. 10, or 10 lea yarn, is ten times 300 yards, or 3000 yards from one pound of hackled ſlax; 40 lea yarn, or 12,000 yards from the pound, is said to be the finest produced in England by machine spinning, though by hand spinning the process has been carried as high as 120 leas to the pound. The average work of every spindle in a spinning * For an account of the quantity of work these machines are capable of performing, and other particulars respecting them, see the Report of the Select Committee of the House of Commons on the subject. Mr. Bundy has likewise invented a very ingenious machine for backling ſlax. mill, where thousands are usually in motion at once, is esti- mated at an average of 12 leas in the day, or 3600 yards; and in spinning the finest yarns the spindle is said to revolve 3000 times in a minute We do not, however, vouch for this almost incredible velocity, not having had an opportunity of calculating the machinery. - The qualities of the tow, or refuse of flax and hemp, and the Various operations performed upon it, cannot here be enume- rated, and explained, among which is that of carding it by machinery, so as to produce useful rovings for spinning infe- r10r yarns. - - - * HENDECAGON, in Geometry, a figure that has eleven sides, and as many angles. 3, HERATIC GAS, the old name for sulphuretted hydrogen. HEPTACHORD, in the ancient poetry, signified verses that were sung or played on seven chords, that is, on seven dif- ferent notes. * HEPTAGON, in Geometry, a figure consisting of seven sides and as many angles. HEPTARCHY, a government of seven persons; also a state or country divided into seven kingdoms, and governed by seven independent princes. England was at one period divi. ded into seven kingdoms, under the Saxons, hence called the Saxon Heptarchy. HERALD, is an officer at arms, whose business it is to denounce war, proclaim peace, or be otherwise employed by the king in martial messages or other business. Heralds are the judges and examiners of gentlemen's coats of arms, and preservers of genealogies, and they marshal all solemnities at the coronation of princes, and funerals of great persons. HERALDS. The heralds, which are six in number, are dis- tinguished by the names of Richmond, Lancaster, Chester, Windsor, Somersº, and York, and are all equal in degree, only preceding according to the seniority of their creation, their patents being under the great seal of England. HERALDRY, is a science which teaches how to blazon or explain, in proper terms, all that belongs to arms; and how to marshal, or dispose with regularity, divers arms on a field. It also teaches whatever relates to the marshalling of solemn pro- cessions, and other public ceremonies at coronations, instal- lation of knights, creations of peers, nuptials, christenings of princes, funerals, &c. Arms, sometimes called coats of arms, are hereditary marks of honour, made up of fixed and determined colours and figures, granted by sovereign princes, as a reward for military valour, or some signal public service: and serve to denote the descent and alliance of the bearer; or to distinguish states, cities, soci- eties, &c. civil, ecclesiastical, and military. Arms are distin- guished by different names to denote the causes of their bearing, such as arms of dominion, of pretension, of concession, of communi- tºl, of patronage, of family, of alliance, of succession, of assumption. Those of dominion and sovereignty are those which emperors, kings, and sovereign states constantly bear; being, as it were, annexed to the territories, kingdoms, and provinces they pos. Sess. Thus, there are the arms of England, of France, &c. Arms of pretension are those of such kingdoms, provinces, or territories, to which a prince or lord has some claim, and which he adds to his own, although such kingdoms or territo- ries are possessed by another prince or lord. Arms of conces- sion, or augmentation of honour, are entire arms, as the fortress of Gibraltar on the escutcheon of Lord Heathfield. Arms of community belong to bishoprics, cities, companies, &c. Of patronvge, to governors of provinces, lords of manors, &c. Arms of family are the property of individuals, and it is criminal in any persons not of the family to assume them. Arms of alliance shew the union of families and individuals. Arms of suc- cession are taken up by those who inherit certain estates, manors, &c. either by will, entail, or donation, and which they impale or quarter with their own; this multiplies the titles of Some families from necessity, and not from ostentation. Of assumption, or assumptive arms, are taken up by the caprice or fancy of upstarts of mean extraction, who, on becoming per- sons of fortune, assume them without a legal title. They are also such as a man of his proper right may assume, with the approbation of his sovereign and of the king of arms. 5 Z * 454 H E R H. E. R. DICTIONARY OF MECHANICAL scſ ENCE : The parts of arms are the escutcheon, the tinctures, charges, and ornaments. Heralds distinguish nine different points in bearing they are charged with, as in the figure. A, the dexter chief; B, precise - middle chief; C, sinister chief; D, ho- N A point; G, dexter base; H, precise mid- ... -- dle base; I, sinister base. . The tinctures mean that variable hue common both to the shields and their. syellow or gold, expressed by dots, white, or argent; red by perpendicular lines: blue or azure by horizontal lines. Purple, - by diagonal lines from right to left; green, by the same from ief: and orange and blood colour are expressed by diagonal lines crossing each other. The charges are those emblems occupying the field of the £scutcheon, or any part of it. All charges are distinguished mon charges. - ſº & Honourable ordinaries, the principal charges in heraldry, are made of lines only, which, according to their disposition and form, receive different names. Sub-ordinaries are ancient are distinguished by terms appropriated to each of them. Common charges are composed of natural, artificial, and even imaginary things, such as stars, animals, trees, ships, &c. The ornaments that accompany or surround escutcheons, person to whom the arms appertain; they are used both by clergy and laity. Those most in use area of ten sorts, viz. crowns, coronets, mitres, helmets, mantlings, chapeaux, wreaths, crests, scrolls, and supporters. arms; it is called crest from the Latin word crista, which sig- nifies a comb, or tuft, such as many birds have upon their heads, as the peacock, &c. Crests were anciently marks of great honour, because they were worn only by heroes of great guished in an engagement, and thereby rally their men if dis- persed. They are at present considered as mere ornaments. The scroll is an ornament usually placed below the shield and supporters, containing a motto or short sentence, alluding It is not our object to dwell on this article, and we will therefore conclude it by noticing briefly that the science of he- raldry consists in blazoning and marshalling arms. The word blazoning is borrowed from the French emblazoner; and signi- of an achievment in proper terms. The blazoning of the arms of gentlemen, esquires, knights, and baronets, is derived from metals and colours; those of barons, viscounts, earls, marquises, and dukes, from precious stones; escutcheons, in order to determine exactly the . positions of the nour point; E, fess point; F, nombril bearings; and there are seven tinctures, to right; black by horizontal and perpendicular lines crossing; by the name of honourable ordinaries,sub-ordinaries, and com- heraldic figures frequently used in coats of arms, aud which were introduced to denote the birth, dignity, or office of the The crest is the highest part of the ornaments of a coat of valour and high rank, that they might be the better distin- thereto, or to the bearing, or to the bearer’s name, fies displaying or explaining the several emblems and colours and those of princes, kings, and emperors, from the planets. Marshalling is the orderly disposition of several coats of arms, belonging originally to different families, within one shield or escutheon, together with all the proper armorial ensigns, ornaments, and decorations. We will in this place first notice the four great orders of British knighthood; second- ly, we will explain the various beraldic terms. - Degrees of Precedency, and different kinds of Arms. The King. Marquises. Princes of the Blood. Eldest sons of Dukes. Archbp. of Canterbury. Earls. Marquises' eldest sons. Duke's younger sons. Wiscounts. Earl’s eldest sons. Lord High Chancellor. Archbishop of York. Lord Treasurer. Lord President of the Coun- cil. Marquises' younger sons. Lord Privy Seal. Bishops. Dukes. Barons. Eldest sons of Dukes of the Speaker of the House of Com- Blood Royal, III.OIAS. \ Degrees of Precedency, and different kinds of Arms Lord Commissioneſ of the ſ Master in Chancery, Great Seal. . . - Viscounts' younger sons. Viscounts’ eldest sons. Barons’ younger sons. Earls’ younger sons. Baronets. - Barons eldest sons. Knights Banneret. * Privy Counsellors not Peers. Knights of the Bath. Knights Bachelors. Baronets' eldest sons. Knights’ eldest sons. Chancellor of the Exchequer. Chancellor of the Duchy. The Knights of the Garter not Peers. Baronets' younger sons. The Lord Chief Justice of the Knights' younger sons. King’s Bench. Field and Flag officers. Doctors graduate. Serjeants at Law. The Master of the Rolls The Lord Chief Justice of the Common Pleas Esquires. The Lord Chief Baron of the Gentlemen. Exchequer. Yeomen. Puisne Judges and Barons. Tradesmen. Knights Banneret, if made Artificers. in the field of battle. Labourers. The ladies, except those of Archbishops, bishops, and judges, take place according to the quality of their husbands, and unmarried ladies take place according to that of their fathers. HERB, in Botany, is that part of the plant which rises from the root, and is terminated by the fructification. It compre- hends the trunk and stem; the leaves; the fulcra, or supports; and the buds, or, as they are sometimes denominated, the winter quarters of the future vegetable. - HERBACEOUS PLANTs, in Botany, are those which have succulent stems that die down to the ground every year. HERCULES, CERBERUs, and the Apple Branch. This con- stellation serves to perpetuate the memory of Hercules, the Theban, son of Amphitryon and Alcmene, famous in ancient times by his wisdom, his heroic labours, and his extraordi- nary strength. Hevelius placed Cerberus, or the Serpent with three heads, by the side of Hercules. If Cerberus be consi- dered allegorically as the symbol of the earth, or more pro- perly of all-devouring time, his three mouths will represent the present, past, and future. The victory which Hercules ob- tained over this monster is thought to denote the conquest this hero acquired over his passions. Dr. Bryant derives this name from Kir Abor, “the place of light,” and the temple of the sun was called Tor-Caph-El, which was changed to rpurnſpaxog, and hence Cerberus (originally the name of a place) was sup- posed to have three heads. Boundaries and Contents.-On the N. by Draco, E. by Lyra S. by Serpentarius, and W. by Serpens and Corona Borealis. There are 113 stars in this constellation, of which seven are or the 3d magnitude, seventeen of the 4th, &c. Ras Algothi, of the 3d magnitude, is situated in the forehead, over the right eye. Ras Algothi, the principal star in this constellation, having 256° 36' 32” right-ascension, and 14° 36' 17" of N. dec., appears on the N. E. by E # E. point of the horizon, and rises and culminates, at London, as in the following Table: Merid. Alt. 530 5' 17" N. - Mo NTH. I. RISES. CULM. MONTH. RISES. CULM. ho. mi. ho. mi. ho. mi. ho. mi. Jan. 3 O M. 10 20 M. July 3 14 A. | 10 28 A. Feb. 12 50 M. 8 0 M. Aug. I 6 A. 8 30 A. Mar. 11 2 A. | 6 10 M. Sept. 11 0 M. 6 30 A. April 9 5 A. | 4 || 5 M. Oct. 9 10 M. 4 40 A. May 7 15 A. 2 30 M. Nov. 7 15 M. 2 45 A. June 5 15 A. | 12 30 A. Dec. 5 10 M. | 12 37 A. HEREDITAMENTS, such things immoveable, whether cor poreal or incorporeal, as a man may leave to his heirs, by way of inheritance; or which, not being otherwise devised, naturally descend. Corporeal hereditaments consist wholly of substan- tial and permanent objects, all of which may be comprehended under the general denomination of land only; incorporeal hereditaments are not the objects of sensation, are creatures of the mind, and exist only in contemplation. They are prin cipally of ten sorts, viz. advowsons, tithes, commons, ways offices, dignities, franchises, presents, and rents. H. E. R. H I D DICTIONARY OF MECHANICAL SCIENCE. 455 “, HERMAPHRODITE, a term, formerly applied exclusively to signify a human creature possessed of both sexes. The term is now applied to other animals, and to plants. It is iow well known there is no such thing as an hermaphrodite in. the human species. In most species of animals, the produc- tion of hermaphrodites appears to be the effect of chance, but in the black cattle it seems to be an established principle of their propagation. It is a well known fact, and, as far as has yet been discovered, appears to be universal, that when a cow brings forth two calves, one of them a bull, and the other a cow to appearance, the cow is unfit for propagation, but the bull-calf becomes a very proper bull. They are known not to breed; they do not shew the least inclination for the bull, nor does the bull ever take the least notice of them. Among the country people in England, this kind of calf is called a free- martin; and this singularity is just as well known among the farmers as either cow or bull. When they are preserved, it is for the purpose of an ox, or spayed heifer, viz. to yoke with the oxen, or fatten for the table. They are much larger than either the bull or the cow, and the horns grow longer and bigger, being very similar to those of an ox. The bellow of a free- martin is also similar to that of the ox, and the meat is similar to that of the ox or spayed heifer, viz. much finer in the fibre than either the bull or cow, and they are more susceptible of growing fat with good food. Among the reptile tribe, indeed, such as worms, snails, leeches, &c. hermaphrodites are frequent. In the memoirs of the French Academy, we have an acconnt of this very extraor- dinary kind of hermaphrodites, which not only have both sexes, but do the office of both at the same time. Such are earth- worms, round-tailed worms found in the intestines of men and horses, land-snails, and those of fresh waters, and all the sorts of leeches. And as all these are reptiles, and without bones, it is inferred, that all other insects which have two characters, are also hermaphrodites. in this class of hermaphrodites may be illustrated in the instance of earth-worms. These little creatures creep, two by two, out of holes proper to receive them, where they dispose their bodies in such a manner, as that the head of the one is turned to the tail of the other. Being thus stretched length- wise, a little conical button, or papilla, is thrust forth by each, and received into an aperture of the other; these ‘animals being male in one part of the body, and female in another. Among the insects of the soft or boneless kind, there are great numbers indeed which are so far from being herma- phrodites, that they are of no sex at all. Of this kind are all the caterpillars, maggots, and worms, produced of the eggs of flies of all kinds. But the reason of this is plain ; these are not animals in a perfect state, but disguises under which animals lurk. They have no business with the propagating of their species, but are to be transformed into animals of another kind, by the putting off their several coverings; and then only they are in their perfect state, and therefore, then only shew the differences of sex, which are always in the distinct ani- mals, each being only male or female. These copulate, and their eggs produce those creatures which shew no sex till they arrive at that perfect state again.-Watkin's Cyclopaedia. HerMAPHRODITE Flowers, in Botany, are so called on ac- count of their containing both the antherae and stigma, the supposed organs of generation, within the same calyx and petals. Of this kind are the flowers of all the classes in Lin- naeus’s method, except the classes monoecia and dioecia. HERMETICAL PHILosophy, is that which professes to explain all the phenomena of nature, from the three chemical principles of salt, sulphur, and mercury. HERMETICAL Sealing, is used to denote a peculiar manner of stopping or closing glass vessels for chemical and other opera- tions, so that not the rarest medium can either escape or enter. This is usually done by heating the neck of the vessel in the flame of a lamp with a blow-pipe, till it be ready to melt, and then with a pair of hot pincers twisting it close together. HERSCHEL, the name frequently given to the new planet discovered by Dr. Herschel; it is otherwise called the Geor- gian, or Georgium Sidus, but now more commonly Uranus. Sir William Herschel, a very celebrated astronomer, who was originally a musician in a marching regiment, but by his genius The method of coupling practised and industry, raised himself to the honour of knighthood, and a name that will live whilst astronomical science shall be cul- tivated. This great observer and ingenious optician lived to a good old age, many years of which he passed at Slough, in the neighbourhood of Windsor, where the principal part of his observations on the heavens were made. HESSE, WILLIAM, PRINce of, one of the greatest pro- moters and encouragers of the sciences in the sixteenth cen- tury. He erected an observatory at Cassel, and furnished it with excellent instruments for the purpose of observing the celestial motions; having called to his assistance Christopher Rothmann and Juste Byrgs: these observations were pub- lished by Wellebrord Snell at Leyden, in 1618, and are of a very curious nature; they are also mentioned by Tycho Brahe, in the second volume of his “Progymnasmata.” This prince died in 1597. HETEROGENEOUS, literally imports something of a different kind, in opposition to homogeneous. . - HETEROGENEOUS Bodies, are bodies of unequal density and composition. . HETERoG ENEous Light, that which consists of rays of differ- ent degrees of refrangibility. HETERog ENEOUS Numbers, consisting of integers and frac- tions. HeteroGENEOUs Quantities, are those which admit of no comparison as to greater or less. Thus, a surface and a solid are heterogeneous quantities, because we can in no way make comparison between them, or say that a surface, however large, is greater than a solid, however small. In this respect it has been said, that momentum and pressure are heterogeneous quantities. - HaTeRogex eo Us Surds, are such as have different radical signs, as 'aa, &/bb, W9 &/18, &c. See SURD. HETEROSCII, in Geography, are such inhabitants of the earth as have their shadows at noon projected always the same way with regard to themselves, or always contrary ways with respect to each other. Thus, all the inhabitants without the torrid zone are heteroscii, with regard to themselves, since any one such inhabitant has his shadow at noon always the same way; viz. always north of him in north latitude, and always south of him in south latitude. HEXACHORD, in ancient Music, a concord called by the moderns a Sixth. - - ; * , HEXAEDRON, or Hex AHEDRon, one of the five regular or platonic bodies, so called from its having six faces. The square of the side or edge of a hexahedron, is one-third of the square of the diameter of the circumscribing sphere ; and hence the diameter of a sphere is to the side of its inscribed hexahedron, as A/3 to 1. HEXAGON, in Fortification, a place defended by six bastions. - HEXAMETER, in ancient Poetry, a kind of verse consist- ing of six feet; the first four of which may be indifferently either spondees or dactyls; the fifth is generally a dactyl, and the sixth always a spondee. Such is the following verse of Horace : 2 3 4 5 6 Aüt präldessé völlint, àit!délècliárá pálētāč. Sometimes, indeed, a spondee constitutes the fifth foot; whence such hexameter verses are called spondaic ; as in this of Virgil:— - * I 2 3 4 5 6 Cárd Délim söbölles mālgmüm Jöväs incrèlmentiſm. Epic poems, as the Iliad, AEmeid, &c. consist wholly of hexa- meter verses; whereas elegies and epistles consist usually of hexameter and pentameter verses alternately. HIATUS, properly signifies an opening, chasm, or gap; but it is particularly applied to those verses, where one word ends with a vowel, and the following word begins with one, and thereby occasion the mouth to be more opened, and the sound to be very harsh. The term Hiatus is also used in speaking of manuscripts, to denote their defects, or the parts that have been lost or effaced. - 456 H I N H I R. DICTIONARY OF MECHANICAL SCIENCE. HIDES, the skins of beasts; but is particularly applied to those of large cattle, as bullocks, cows, buffaloes, horses, &c. Raw or green hide, is that which has not undergone any pre- paration. There are also hides dried in the hair. Salted hide, is a green hide seasoned with sea salt and alum or saltpetre, to prevent its corruption. See CURRYING and TANNING. Hide of Land, was such a quantity of land as might be ploughed with one plough within the compass of a year. HIERARCHY, the subordination of the clergy, ecclesiasti- cal polity, or the constitution of the ‘Christian church consi- dered as a society. - HIEROGLYPHICS, in antiquity, mystical characters or symbols, in use among the Egyptians, and that as well in their writings as inscriptions; being the figures of various animals, the parts of human bodies, and mechanical instruments. The meaning of a few of these hieroglyphics has been preserved. They represented the Supreme Deity by a serpent, with the head of a hawk. The hawk itself was the hieroglyphic of Osiris; the river-horse, of Typhon; the dog, of Mercury ; the cat, of the Moon or Diana; the beetle, of a courageous war- rior. To decipher the more ancient hieroglyphics has hitherto baſſled the ingenuity of the learned, but by a comparison of inscriptions which have been written in Greek, the hieroglyphic characters used for letters in writing proper names have been fully ascertained; and hence many inscriptions which were not accompanied by a corresponding Greek inscription, have been deciphered. In every other respect, the subject is in as much obscurity as ever. HIGH WATER, that state of the tides when they have flowed to the greatest height, in which state they remain nearly sta- tionary for about 15 or 20 minutes, when the water begins again to ebb. The time of high water is always nearly the same in the same place at the full of the moon, and at all other times the time of high water depends upon the age of the moon. The rule for finding which, the age of the moon being given, is as follows, viz. Add + of the days of the moon’s age, as so many hours, to the time of high water at the full of the moon, and the sum is the time of high water, answering to that day nearly. The time of high water at London, on the day of the full moon, is three o’clock in the afternoon. HIGHWAY, a public passage for the king's people, whence it is called the king's highway. There are three kinds of ways, a footway, a pack and prime way, which is both a horse and foot way, and a cart way, which contains the other two. A river, common to all men, may also be called the king’s high- way; and nuisances in any such ways are punishable by indictment. If passengers have used, time out of mind, where the roads are bad, to go by outlets on the land adjoining to an highway in an open field, such outlets are parcels of the high- way; and therefore, if they are sown with corn, and the track is found and can be trodden, the king's subjects may go upon the corn. See ROAD. Repairing Highways. – By the common law, the general charge of repairing all highways lies on the occupiers of the lands in the parish wherein they are. But it is said that the tenants of the lands adjoining are bound to scour their ditches. Particular persons may be burdened with the general charge of repairing an highway, in two cases; in respect of an enclo- sure, or by prescription; but the parish cannot take advantage of this on the general issue, but must plead it specially. At common law, it is said, that all the county ought to make good the reparations of an highway, where no particular persons are bound to do it. By the ancient common law, villages are to repair their highways, and may be punished for their decay; and if any do injury to, or straighten the highway, he is punishable in the King’s Bench, or before the justices of peace in the court-leet, &c. Destroying any public turnpike-gate, or the rails or fences thereto belonging, subjects the offender to hard labour, or transportation for seven years. Every justice of the peace, by the statute, upon his own view, on on oath made to him by the surveyor, may make present- ments of roads being out of repair; and thereupon, like pro- cess shall be issued as upon indictment. HIN, a Hebrew measure of capacity for things liquid, con- taining the sixth part of an epha, or one gallon two pints, English measure. HIND, a female stag in the third year of its age. See Cekvus. HINGES, the joints on which gates, doors, lids, folds of tables, &c. hang and turn in opening, shutting, and folding. HIP Roof, among carpenters, called also Italian Roof, is a roof which has neither gable-head, shread-head, nor jerken- head, (by which is meant such heads as are both gable and hip at the same end;) for it is a gable or upright, as high as the collar beam, and then there are two short hips, which shut up with their tops to the tops of a pair of rafters, which country carpenters call singlars. A hip-roof has rafters as long, and with the angle of the foot, &c. at the ends of buildings, as it has at the sides; and the feet of the rafters, at the end of such buildings as have hip-roofs, stand on the same plane, viz. parallel with the horizon, and at the same height from the foundation, with rafters on the sides of the roof. -- HIPPOCRATES, of Chios, a celebrated mathematician of antiquity, who flourished about 450 years before Christ, and to whom we are indebted for the curious property of the lumes, which bear his name, and which were the first curvilinear spaces whose quadrature was precisely determined. See LUNEs. Hippocrates was originally a merchant, and is represented as having been a man of extreme simplicity, and very negligent of his own, affairs, whereby he was nearly ruined. This circum- stance brought him to Athens to arrange his concerns, and here it seems that, by chance, he first acquired some knowledge of geometry, which he afterwards prosecuted with the greatest success, and taught it in the school of Pythagoras, from which, however, it is said he was afterwards expunged for having received money for his instruction. - HIPPOPOTAMUS, in Natural History, a genus of mamma- lia, of the order bellua. This animal is supposed to be the behe- moth described in the book of Job. When full-grown, they are from 11 to 12 feet in length. Mr. Bruce reports, that they are occasionally found even of the length of twenty feet. Their form is awkward : the head astonishingly large, and the body extremely fat and round; the legs are very short and thick, and the teeth of vast strength and size. The whole animal is covered with short hair; its skin is so tough, as in some parts to resist a bullet; and its colour, when dry, is an obscure brown. It inhabits the warmer latitudes, and is to be found chiefly in the interior of Africa, in the largest rivers, in which it ranges at the bottom, sometimes reaching the surface for the purpose of respiration. By night it quits the water to feed, and devours a vast quantity of grass, and the tender branches of trees. Its disposition has nothing in it sanguinary or fero- cious; it never attacks other animals. It frequently commits great depredations on the plantations of corn or sugar which are within the reach of its nocturnal progresses, and by destroy- ing with its vast teeth the roots of trees. Its motion on land is inelegant and slow ; yet if surprised and pursued, it runs with great speed till it reaches the water, into which it instantly plunges; and though it is able to swim with great rapidity, its progress in the water is at the bottom by walking. If wounded in the water, it sometimes is highly infuriated, and has been known to attack the boats or canoes, which it supposed to con- tain its enemy, and overturn them by its vast strength, or sink them by making a large hole in them with its teeth. It pro- duces but one at a birth, generally in the little rushy isles of the rivers which it frequents, and in these islets it generally sleeps. When taken young, it is capable of being tamed. These animals are sometimes seen in considerable numbers, ranging for several miles beyond the banks of their rivers. They are valued by the natives of Africa for food, and the fat which it supplies is supposed to be equal to that of the hog. The feet are highly gelatinous, and regarded as a particular delicacy. With their skins the warriors of Africa are furnish- ed with shields and bucklers. Their tusks are whiter than those of the elephant, and retaining their original clearness and beauty, are preferred by dentists for artificial teeth to every other substance. - -- ~- HIRE, PHILIP De LA, an eminent French mathematician and aströhomer, was born at Paris in 1640. De la Hire was employed with Picard in making the necessary observations for constructing a new and accurate map of France, a task which he executed with the greatest ability, at the same time * H I R. II O L 457 DICTIONARY OF MECHANICAL SCIENCE. making other observations on the height of mountains, the variation of the magnetic needle, &c. HIRUDO, the Leech, a genus of the vermes intestina class and order. The body moves either forward or backward. There are seventeen species, principally distinguished by their colour. The most remarkable is the medicinal leech, which grows to the length of two or three inches. The body is of a blackish brown colour, marked on the back with six yellow spots, and edged with a yellow line on each side; but both the spots and the lines grow faint, and almost disappear at some seasons. The head is smaller than the tail, which fixes itself very firmly to any thing the creature pleases. It is viviparous, and produces but one young at a time, which is in the month of July. It is an inhabitant of clear running waters, and is well known for its use in bleeding. The mouth of the leech is armed with a sharp instrument, that makes three wounds at once, and may be com- pared to the body of the pump, and the tongue or fleshy nipple to the sucker; by the working of this piece of mechanism the blood is made to rise up to the conduit which conveys it to the animal’s stomach, which is a membranaceous skin, divided into twenty-four cells. The blood which is sucked out is there preserved for several months, almost without coagulating, and proves a store of provision to the animal. It is used in medi- cine, being applied to the skin in order to draw off blood. W. this view they are employed to phlebotomize young chil- ren. put on the spot it is wished to fix on, or a little blood is drawn by means of a slight puncture, after which it immediately set- tles. The leech, when fixed, should be watched, lest it should find its way into the anus when used for the hemorrhoids, or penetrate into the oesophagus, if employed to draw the gums. In such a case, the best and quickest remedy is to swallow some salt; which is the method practised to make it loose its hold when it sucks longer than it was intended. H. sanguisuga, horse leech: is elongated, olive-brown, with on ochre-yellow marginal band; found in stagnant waters, ditches, and ponds; from four to six inches long : body above dull olive black, with an ochre margin on each side; beneath paler, with sometimes a few black spots: tail thicker than the head. This species sucks blood with great avidity, and in large quantities. - HIRUNDO, the Swallow, in Natural History, a genus of birds of the order passeres. These live almost perpetually in the air, and perform in it every act of their nature. They subsist upon the insects with which that element abounds, and which they catch on the wing with admirable dexterity; and for this purpose they are furnished with a most extraordinary power of distending their jaws. The service they perform to man by their incessant assiduity in this work of destruction is not lightly to be appreciated, and those who observe the crowd- ed population of the atmosphere through the beams of a sum- mer evening, will easily be led to believe that, but for the in- terception of incalculable myriads of insects by these birds, the annoyance of man by these minute animals would be highly distressing, and perhaps almost intolerable. Various opinions have been formed of the state in which they exist during the time of their disappearance: some imagining them to lie torpid in the banks of rivers, or in decayed trees, or in ruined edifices or vaults: and others, that they retire for the winter from the air to the water, lying in immense clusters, like swarms of bees at the bottoms of rivers. Particular facts are on record, by respectable testimony, in favour of both these hypotheses. It is also attested, on similar authority, that migrations of these birds actually take place, and that they quit this country towards winter, for one where they may enjoy a milder climate, and more plentiful food. They are to be met with in every country of the world, and in all, or nearly so, are found to be migratory. There are thirty-seven species. The house swallow, appears in March in this country, and leaves it in September. It generally builds in chimneys, or under the eaves of houses, and will return, unless interrupted, to its original haunt for a number of years. These birds breed twice a year. They are easily rendered familiar; and it has been calculated that a single swallow will devour from seven hundred to a thousand flies in one day. The martin arrives in this country rather later than the swal- 48. If the leech does not fasten, a drop of sugared milk is d the magazine, the bread room, &c. low, and remains longer. It builds often in the crags of rocks near the sea; often under the eaves and cornices of houses. As soon as the young are able to fly, they are fed by the old birds upon the wing, by a process so rapid and instantaneous, as almost to be deemed incredible by those who have not actually witnéssed it. Before their departure, they collect in immense flocks in the small islands of the Thames, where they roost, and in their ſlights about which they almost obscure by their numbers the face of the sky. - The swift arrives later and quits sooner than any other spe- cies, and is also larger and stronger. It builds in elevated situations, particularly about churches and steeples. As these birds catch at almost every thing in the air, they are taken sometimes by a cock-chaffer or other insects tied to a thread. They retire during the heat of the day, but in the morning and evening are incessantly on the wing, taking higher and bolder flights than the swallows, and always keeping separate from them. They leave this island in August. The Chinese swallow, is said to be less than the wren by some authors, while others attribute to it the size of the martin. This bird is principally remarked for its nest, which is regard- ed as one of the greatest luxuries on which the epicure can banquet. k HISTORY, is a connected recital of past or present events. It is the office of the historian to trace the progress of man from the savage state and through the intermediate degrees of civilization, to the nearest approach to perfection of which social institutions are capable. It falls within his province to note the effects of laws and political regulations, and to record the revolutions which have been produced in states by exter- nal violence, or the gradual corruption of ancient systems of government. The record of past transactions, when diligently and minutely examined, will present to the politician matter of warning and of instruction, and, in a moral point of view, his- tory is extremely useful, as it points out the issues of things, and exhibits, as its general result, the reprobation consequent upon vice, and the glory which awaits virtue. \ The student of history must make himself master of the de- tails of geography, the principles of statistical calculations, and the minutiae of chomological researches. He ought likewise to be animated by a spirit of philosophical inquiry, that he may distinguish truth from falsehood, and be able to deduce useful consequences from the facts passing in review before him, in the obscure records of former times, or amidst the misrepre- sentations of factious malignity. He must have a minute knowledge of the human heart, and give due weight to circum- stances and situations. Let him not direct his chief attention to thc frivolous anecdotes of a court, but to the circumstances which stamp the character and decide the destiny of a nation. HIVE. See BE E. - s HOD, an instrument used to carry bricks and mortar in up ladders. HOE, in country affairs, a tool made like a cooper’s adze, to cut upwards, in gardens, fields, &c. HOKE DAY, the Tuesday after Easter week, which was the day on which the English conquered and expelled the Danes; this was therefore kept as a day of rejoicing, and a duty, called, Hoke Tuesday money, was paid to the landlord, for giving his tenants and bondmen leave to celebrate it. HOLCUS, Indian Mullet, or Corn, a genus of the polygamia monoecia class and order of plants. Natural order of grasses. Essential character: hermaphrodite, calyx glume, one or two flowered ; corolla glume, awned ; stamina three ; styles two; seed one ; male, calyx glume, two-valved; corolla none ; sta- mina three. There are 15 species. HOLD, the whole interior cavity or belly of a ship, or all that part of her inside which is comprehended between the floor and the lower deck, throughout her length. This capa- cious apartment usually contains the ballast, provisions, and stores of a ship of war, and the principal part of the cargo in a merchantman; in the former it is divided into several apart- ments (by bulk-heads) which are denominated according to the articles which they contain, as, the fish-room, the spirit-room, See the article STOWAG E. The after Hold, is that which lies abaft the main mast, and is usually set apart for the stowage of the provisions in ships of war, - 6 A - 458 H O M. H. O. N. DICTIONARY OF MECHANICAL SCIENCE. The fore Hold, denotes that part of the hold which is situ- ated in the fore part of the ship, or about the fore hatchway. It is usually in continuation with the main-hold, and serves the Same purposes. - * , - . The main-Hold, that part which is Just before the main-mast, and which generally contains the fresh water and beer for the use of the ship's company. Hold Fast, a large piece of iron, in the shape of the letter s, fixed into the wall to strengthen it. Also a tool used by joiners, carvers, &c. which goes through their benches to hold fast work that cannot be finished in the hand. HOLLAND, a fine and close kind of linen, so called from its being first manufactured in Holland. . HOLLOW SQUARE, in the Military art, a body of foot soldiers drawn up, with an empty space in the middle for colours, baggage, &c. . . . - HOLOCENTRUS, a genus of the order of the thoracici, of which there are 35 species. - HOLOMETER, a mathematical instrument that serves uni- versally for taking all measures, both on the earth and in the heavens. w HOME, in a Naval sense, signifies the situation of some object where it retains its full force of action, or where it is properly lodged for convenience or security. In the former sense, it is applied to the sails, and in the latter it usually refers to the stowage of the hold, or the anchors. * To haul Home the Topsail-sheets, is to extend the bottom of the top-sail to the lower yard-arms by means of the sheets. Sheet Home: the Top-gallant-sails, the order to extend the clues of those sails to the top-sail yard-arms. In the stowage of the hold, a cask is said to be home when it bears against or lies close to some other object, and indeed the security or firmness of the stowage greatly depends on this circumstance. - gº The Cartridge is Home, i. e. is rammed close down, so as that the priming-wire may pierce it through the touch-hole. HOMER, OMER, Corus, or Chomer, in Jewish antiquities, a measure containing ten baths, or seventy-five gallons and five pints, as a measure for things liquid; and thirty-two pecks and one pint, as a measure for things dry. - HOMICIDE, in Law, the killing of a man by man. Of this there are several species, as homieide by self-defence, homi- cide by misadventure, justifiable homicide, manslaughter, chance medley, and murder. Homicide by self-defence, or se defendendo, is where one has no other possible means of pre- serving his life from one who combats with him on a sudden quarrel, and kills the person by whom he is reduced to such inevitable necessity. & HoMICIDE, by misadventure, is where a man in doing a law- ful act, without any intent to hurt, unfortunately chances to kill another. Neither homicide by misadventure, nor homicide se defendendo, are felonious, because not accompanied with a fêlonious intent. HOMICIDE, Justifiable. To make homicide justifiable, it must be owing to some unavoidable necessity, to which a person who kills another must be reduced, without any manner of fault in himself. Justifiable homicide of a public nature is such as is occasioned by the due execution or advancement of public justice. * - HomicIDE, Manslaughter, is either with or without malice; that which is without malice is called manslaughter, or some- times chance medley, or chaud medley; by which is understood such killing as happens either on a sudden quarrel, or in the commission of an unlawful act, without any deliberate inten- tion of doing any mischief at all. The only difference between murder and manslaughter is, that murder is upon malice aforethought, and manslaughter upon a sudden occasion. Chance, or Chaud Medley. Authors of the first authority disagree about the application of this word. By some it is ap- plied to homicide by misadventure, by others to manslaughter. Murder is the highest crime against the law of nature that a man is capable of committing. It is, when a man of sound memory, and at the age of discretion, unlawfully kills another person under the king's paece with malice aforethought, either expressed by the party, or implied by the law, so as the party wounded or hurt die of the wound or hurt within a year and a day, the whole day on which the hurt was done, being reckoned the first.—The law so far abhors all duelling in cold blood, that not only the principal who actually kills the other, but also his seconds and those of the persons killed are accounted guilty of murder. . - - - HOMINE REPLEGIANDo, a writ to bail a man out of prison. HOMO, Man, in Natural History, is ranked by Linnaeus under the order primates, which is characterized by having four cutting teeth in the upper and lower jaw, and two mammae in the breast. - - HOMOGENEAL, or Ho Mogeneous, is a term applied to various subjects to denote that they consist of similar parts, or of parts of the same nature and kind; in contradistinction to heterogeneous, where the parts are of different natures, &c. Natural bodies are generally composed of homogeneous parts, as a diamond, a metal, &c. Artificial bodies, on the contrary, are assemblages of heterogeneous parts, or parts of different qualities, as a building of stone, wood, &c. HomogeneAL Light, is that whose rays are all of one and the same colour, degree of refrangibility, and reflexibility. - Thus if the ratio of A to B be the same as that of C to D A is homologous to C as B to D; because of the similitude between the antecedents, and consequents. The two antece- dents and the two consequents, then, in any continued geome- trical proportion, are homologous terms, tº . Thus, the base of one triangle is homologous to the base of another similar triangle; so in similar triangles, the sides opposite to equal angles are said to be homologous. * Equiangular, or similar triangles, have their homologous sides proportional. - All similar triangles, rectangles, and polygons, are to each other as the squares of their homologous sides. . HOMOGENEOUS SURDs, those which have the same radi- cal character or signs, as 3' va, and 3' b. HOMOLOGOUS, in Geometry, an appellation given to the corresponding sides and angles of similar figures, as being proportional to each other. HONE, a fine kind of whetstone, used for setting razors, &c. HONEY, is a sweet and fluid substance, which is collected from flowers, and deposited in the cells of the combs for sup- port of the bees and their offspring. The honey made by young bees is purer than any other, and is thence called virgin honey. Before the discovery of sugar, honey was of much greater importance than it is at present. Yet, both as a delicious article of food, and as the basis of a wholesome fermented liquor called mead, it is of no mean value even in this country; but in many parts of the continent, where sugar is much dearer than with us, few articles of rural economy, not of primary importance, would be dispensed with more reluctantly than honey. In the Ukraine, some of the peasants have each 400 or 500 bee-hives, and make more profit of their bees than of corn. And in Spain the number of hives is almost incredible; a single parish priest is stated to have possessed 5000. HONEY-COMB, in Gunnery, is a flaw in the metal of a piece of ordnance, when it is ill cast and spongeous. See the arti- cle GUN. . g - HONOUR, in Law, is used especially for the more noble - sort of seigniories on which other inferior lordships or manors depend, by performance of some customs or services to those who are lords of them. Before the statute 18 Edward I. the king’s greater barons, who had a large extent of territory holden under the crown, frequently granted out smaller manors to inferior persons to be holden of themselves: which therefore now continue to be held under a superior lord, who is called in such cases the lord paramount over all these manors; and his seigniory is frequently termed an honour, not a manor, espe- cially if it has belonged to an ancient feudal baron, or been at any time in the hands of the crown. When the king grants an honour with appurtenances, it is superior to a manor with ap- purtenances; for to an honour, by common intendment, apper- tain franchises, and by reason of those liberties and franchises, it is called an honour. - HoNour, Courts of Those which determine disputes con- cerning precedency and points of honour. * HONOURS, Milita RY. All armies salute crowned heads in the most respectful manner, colours and standards dropping, H O P H O R. 459 DIC rion ARY OF MECHANICAL SCIENCE. and officers saluting. Different ranks of officers are saluted in a different mode. - HoNours of War, are terms granted to a vanquished enemy, and by which he is permitted to march out of town, &c. with all the insignia of military etiquette. - w - HOOD, a sort of low wooden porch, resembling the compa- nion, (which see) of the master’s cabin, and is placed over the ladder which leads to the steerage in merchant ships. Its use is to prevent the rain from falling into the steerage, but at the same time to admit the air and light. f r HooD, is also a name given to the upper part of a galley- chimney, which being in the shape of the letter L reversed, is trimmed or turned round according to the various directions of the wind, that the smoke may always fly to leeward. Fore Hood, or After Hood, or Whood, or Whooden Ends, a name given to the ends of the planks which are let into the channels of the stem and stern-post. Hood, of a Pump, a short semi-cylindrical frame of wood, serving to cover the upper wheel of a chain-pump. Naval Hoods, or WHooDs, large thick pieces of timber, which encircle the hawse-holes. w - HOOK, a crooked piece of iron, of which there are several kinds, of different shapes and sizes, used at sea; as boat- hooks, breast-hooks, can-hooks, cat-hooks, fish-hooks, &c, which see. Foot-hooks are the same as FUttocks, which see. Laying Hook, a winch for twisting a rope, used in rope- making. Loof Hooks, a tackle with two hooks, one to hitch into a cringle of the main or fore-sail in the bolt-rope, at the leach of the sail by the clew, and the other is to hitch into a strap which is spliced to the chess-tree. Their use is to pull down the sail, and succour the tackle in a large sail or stiff gale, that all the stress may not bear upon the tack. It is also used when the tack is to be seized more secure, and to take off or put on a bonnet or drabler. - Hook and Butt, the scarfing or laying two ends of planks over each other. Hook Pins, are bolts made with a shoulder at one end, and used by carpenters in framings. - HOOKE, Robert, a celebrated mathematician, was born in the Isle of Wight, in 1635, and very early gave proofs of a very superior genius: he was first an assistant to Dr. Wallis, and afterwards to Mr. Boyle, to whom he was very useful in the construction of his air-pump. He was a man of great mecha- nical genius, and the sciences are indebted to him for several valuable instruments and improvements. The following are the inventions and discoveries to which he laid claim : The wheel barometer; a scapement for maintaining the vibration of the pendulum; the double-barrelled air-pump : the conical pendulum; an engine for cutting clock and watch wheels; a method of supplying air to a diving-bell; a reflecting quadrant; the marine barometer; the marine gage; a uni- versal joint for mechanical purposes; besides a great variety of other mechanical contrivances, which our limits will not admit of detailing. His writings are both numerous and valuable; but all his discoveries and inventions are now the common property of science. Hooke was professor of mathe- matics in the Royal Society, and at Gresham College, London, where he died in 1702. HOPPER, a kind of basket, wherein the seed-corn is car- ried at the time of sowing. It is also used for the wooden trough in a mill, into which the corn is put to be ground. See MILL. HOPS, the dried flower-buds of a British climbing plant, which in some parts of England grows wild; but which gene- rally are cultivated in plantations that require the growth of some years before they are in perfection. The plants begin to push up their young stems about the month of April. When these are three or four inches above the ground, poles about twenty feet high are driven in to support them in their growth. The season for picking hops usually commences about the mid- dle of September. This work is performed by men, women, and children. Proper baskets, bins, or cribs, being in readiness, the plants are cut off close to the ground, and the poles drawn up. These are placed upon the bins, with the plants upon them, and three or more persons on each side pick off the hops. • After this they are dried in a kiln, and when dry, are carried into, and kept for five or six days in an apartment called the stowage room, until they are in a state to be put into bags. This is done through a Sround hole, or trap, cut in the floor of the stowage-room, exactly equal to the dimensions of the mouth of the bag, and immediately under which to a frame of wood this mouth is fastened. In each of the lower corners of the bag a small handful of hops is tied ; and a person called the packer places himself in it, and, by a heavy leaden weight, which he constantly moves round in the places where he is not treading, presses and forces the hops down, in a very close manner, into the bag, as fast as they are thrown to him by another labourer. The work thus proceeds till the bag is quite full, when each of the upper corners has a few hops tied in it, in the same manner. HORARY, or Hou R CIRCLE of A Globe, is a small brazen circle, fixed upon the brazen meridian, divided into twenty- four hours, having an index moveable round the axis of the globe, which upon turning the globe fifteen degrees, will shew what places have the sun an hour before or after us. HoRARY Circles or Lines, in Dialling, are the lines or circles which mark the hours on sun-dials. See DiALLING. , HoRARY Motion of the Earth, the arch it describes in the space of an hour, which is nearly 15 degrees, though not accurately so, as the earth moves with different velocities, according to its greater or lesser distance from the sun. HORDE, in Geography, is used for a company of wandering people, which have no settled habitation, but stroll about, dwelling in waggons or under tents, to be ready to shift as i. as the herbage, fruit, and the present produce, is eaten alſ (2. j HORDEUM, in Botany, Barley, a genus of the triandria digynia class and order. Natural order of grasses. Essential character: calyx lateral, two-valved, one-flowered, by threes, at each toothlet of the rachis. There are nine species. HORIZON, the line that seems to link the land or sea and sky; and it is either rational or sensible. The Rational, True, or Astronomical HoRIzoN, which is also called simply and absolutely the horizon, is a great circle, whose plane passes through the centre, of the earth, and whose poles are the zenith and nadir. It divides the sphere into two equal parts or hemispheres. - The Sensible, Visible, or Apparent HoRIzoN, is a lesser circle of the sphere, which divides the visible part of the sphere from the invisible. Its poles are likewise the zenith and nadir; and consequently the sensible horizon is parallel to the rational, and it is cut at right angles, and into two equal parts, by the vertical. These two horizons, though distant from each other by the semidiameter of the earth, will appear to coincide, when continued to the sphere of the fixed stars, because the earth compared with this sphere is but a point. The sensible hori- zon is divided into eastern and western. The Eastern or Ortive HoRIZON, is that part of the horizon wherein the heavenly bodies rise. The Western or Occidual HoRIzoN, is that wherein the stars Set. By sensible horizon is also frequently meant a circle, which determines the segment of the surface of the earth, over which the eye can reach ; called also the physical horizon. In this sense we say, a spacious horizon, a narrow scanty horizon. It is manifest, from the annexed figure, that the * higher the spectator is rais- ed above the earth, the far- ther this visible horizon will extend, as the respective dis- tances A D, B.A., will be the greater. On account of the refraction of the atmosphere, distant objects on the horizon appear higher than they really are, or appear less depressed below the true horizon SS, and may be seen at a greater dis- tance, especially on the sea. Legendre says, that, from several experiments, he is induced to allow for refraction a 14th part of the distance of the place observed, expressed in degrees and minutes of a great circle. Thus, if the distânce be 14,000 ag —6- S C 460 H. O. R. H O R. DICTIONARY OF MECHANICAL scIENCE. toises, the refraction will be 1000 toises, equal to the 57th part of a degree, or 1' 3". - © ſº Horizon of a Globe, the broad wooden circular ring in which the globe is fixed. On this are several concentric cir- cles, which contain the months and days of the year, the cor- responding signs and degrees of the ecliptic, and the 32 points of the compass. Artificial HoRizon, is a contrivance intended to be employed in taking altitudes with Hadley’s quadrants, of which there are several constructions. HORIZONTAL, something relating to the horizon; or that is taken in, or on a level with the horizon. 1. HoR1zoNTAL Dial, is one drawn on a plane parallel to the horizon, having its gnomon or style elevated according to the altitude of the pole of the place it is designed for. HoRIzoNTAl Distance, is that estimated in the direction of the horizon. - HoRIzoNTAL Line, in Perspective, is a right line drawn through the principal point, parallel to the horizon; or it is the intersection of the horizontal and perspective planes. HoRizont Al Line, or Base of a Hill, in Surveying, a line drawn on the horizontal plane of the hill, or that on which it stands. HoRizont AL Plane, in Perspective, a plane parallel to the horizon, passing through the eye, and cutting the perspective plane at right angles. HoRizont AL Range, of a piece of ordnance, is the distance at which a ball falls on or strikes a horizontal plane, whatever be the angle of elevation or direction of the piece. When the piece is pointed parallel to the horizon, the range is then called the point-blank, or point-blank range. The greatest horizontal range, in the parabolic theory, or in a vacuum, is that made with the piece elevated to 45 degrees, and is equal to double the height from which a body must freely fall, to acquire the velocity with which the shot is discharged. But in a resisting medium like the atmosphere, the elevation of the piece, to shoot farthest, is always below 45 degrees, and gradually the more below it as the velocity is greater; so that the greater velo- cities with which balls are discharged from cannon with gun- powder, require an elevation of the gun equal to but about 30 degrees, or even less. And the less the size of the balls is, too, the less must this angle of elevation be, to shoot the farthest with a given velocity. See GUNNERY. HoRizont Al Speculum, consists in a well polished metal speculum, about three or four inches in diameter, enclosed within a rim of brass; so fitted, that the centre of gravity of the whole shall fall near the point on which it turns. HORN. The horns of oxen are used for many of the same purposes as bone. After having been softened by heat, they are capable of being moulded into almost any shape. They are sometimes stained in such a manner as to imitate tortoise shell, and are then used for the making of combs. By a peculiar process they are rendered semi-transparent, and when formed into thin plates, are employed instead of glass for lanterns. Horn was the first transparent matter that was ever used for lanterns and windows. HoRN, is also a musical instrument of the wind kind. The French horn is bent into a circle, and goes two or three times round, growing gradually bigger and wider towards the end, which in some horns is nine or ten inches over. HoRNs of Insects, the slender oblong bodies projected from the heads of those animals, and otherwise called antennae, or feelers. The horns of insects are extremely various; some being forked, others plumose or feathered, cylindrical, taper- ing, articulated, &c. Some have imagined they served to wipe and defend the eyes; others, that they served as feelers, lest the creature should run against any thing that might hurt it; and others think them the organs of smelling. HoRN Ore, in Mineralogy, is one of the species of silver ore ; its most frequent colour is pearl-grey. It is found massive, disseminated in thick membranes, in roundish hollow balls; also crystallized. It occurs in veins, and is usually accom- panied with brown iron ochre, and with silver glance. HORNSTONE, or HoRNsteeN, in Mineralogy, a species of the flint genus, divided into three sub-species: the splintery, the conchoidal, and the woodstone. The most common colour of the splintery hornstone is gray; it is found in veins, in the shape of balls, in lime-stone. The best mill-stone, called French burr, is cellular splinter hornstone. Conchoidal horn- stone occurs in beds with agate, and is distinguished from the splintery by the lightness of its colours and fracture. In the woodstone several colours occur together, and it commonly exhibits coloured delineations, arranging themselves in the direction of the original woody texture. HoRN Work, in Fortification, an outwork composed of two demi-bastions, joined by a curtain. - HORNBLENDE, in Mineralogy, a species of the clay genus, of which there are four sub-species; viz. the common, the Labrador, the basaltic, and the hornblende slate. The com- mon hornblende is of a greenish black, or raven-black, which in some varieties approaches to a grayish and even velvet black. The common hornblende forms one of the essential ingredients of several mountain rocks. When pure, it is a capital flux for iron ores, to which purpose it is applied in Sweden. The Labrador hornblende, found in the island of St. Paul, on the coast of Labrador, is usually of a brownish black. The hornblende slate is of a colour intermediate be- tween greenish and raven black: it is massive, and is generally mixed with nuica and felspar. It occurs in beds of primitive rocks, particularly in clay slate; also in gneiss and mica slate, and is found principally in the northern parts of Europe. The basaltic hornblende is of a velvet black, occurs almost always in single imbedded crystals. The surface is smooth and shin- ing, except where it happens to be covered by a thin ochery crust. HOROLOGIUM, the Clock, in Astronomy, is a modern con- stellation, bounded on the N. and W., by Eridanus, S. by Hydrus, and E. by Reticulus Rhomboidalis, Dorado, and Equu- leus Pictorius. - HOROLOGY, that branch of mechanical science which enables us to measure the portions of time. We judge of the lapse of time by the succession of sensible events; and the most convenient and accurate measures of its quantity are derived from motions, either uniform, or repeated at equal intervals. Of the former kind the rotation of the earth on its axis is the most exact, and the situation of its surface with regard to the fixed stars, or less simply with regard to the sun, constitutes the means for determining the parts of time as they follow each other. Of the latter kind, the rotation of machi- nery, consisting of wheel-work, moved by a weight or spring, and regulated by a pendulum or balance, affords instruments of which the utility is well known. But the term horology is at present more particularly confined to the principles upon which the art of making clocks and watches is established. See CLock, DIALLING, WATCH, &c. Under this article we may describe some ALARUMS. Simple Alarum.—An alarum being a most useful piece of furniture, at one time or another, in every house, perhaps the sketch of one, both cheap and simple, as well as original, may not be unacceptable to our readers. - Description.—A B and CD are two uprights, of wood. E F and F C are two small pieces of wood, with small hinges or pins, at E and C. G is a vessel made of glass or tin, and suspended from F, to contain water, under which is placed the lamp, H. By the heat of the lamp the water gradually eva- porates or flies off in steam, which, lightening the vessel, G, allows the piece of wood, E F, mov- ing on the hinge at E, to escape from under the point, F, of the piece of wood, FC, which flies up, from the strength of the º N. N Nº. --- º º Nº. º º º º º | º . - º º - - º - ºv º º º -- - Mººney ºr 1. B L () () D H () tº sº. 2 (; A R T H () tº sº. by Henry Fisher son & Cº. Caxton London 1827 - Published H O R. H O R. DICTIONARY OF MECHANICAL scIENCE. 461 2 spring of the bell, to the wheel or pulley, I, and thus sets the bell at liberty and causes it to ring. J is a bracket or triangular piece of wood, to prevent the vessel, G, from falling on the lamp after the bar, EF, has escaped from under it. - e The quantity of water for a certain number of hours, the size of the wick, &c. can be calculated, with ease, from a few hours’ observation. A slit should be cut perpendicularly in the piece FC, so that the thread by which the vessel is suspended may be shifted nearer towards C, as occasion may require. g Cheap Alarum.—A is a board about a foot square, in the centre of which is inserted an upright piece B, through which, a cross piece, C, passes, confined by a wire pin, but having the aperture through which it passes in the upright piece B, cut as described by the . - dotted lines at D D. To the end E is at- tached a weight, move- able backwards or for- wards at pleasure. On the opposite end of the beam C, is fixed a tin vessel, F, which re- ceives the sand as it runs out of the funnel G, which is fastened to a fixed beam, H. I is a common spring - bell, also fixed to the A. - top of the upright post, B. K is a wire, or piece of fine cord passing from the spring of the bell to the upper end of a small lever, L, which traverses on an axle, M, fixed to the side of the upright piece B, the other or lower end of the leaver L presses against a peg, N, projecting from the side of the cross beam C, which retains the lever L in the position represented in the figure, and confines the spring of the bell, till the weight of the sand run out of the funnel G into the vessel F more than counterbalances the weight at the end, E, when, of course, the end, O, of the cross beam will be depressed, which will suddenly release the lower end of the lever L from the peg N, and thus the spring of the bell will re-act with sufficient force to put the bell in motion. Any quantity of sand may be put into the funnel G: thus if 2 ounces should run one hour, 12 ounces will run six ; therefore by having the weight P 12 ounces (after having balanced the cross beam C with the empty vessel F,) it is obvious that as the sand continues running, in a few minutes the vessel containing the sand must predominate and be depressed, which is all that is required, as shewn in the figure. w HOROSCOPE, in Astrology, is the degree of the ascendant, or the star that rises above the horizon, at a certain moment, which is observed in order to predict some future event. The same name is also given to a scheme or figure containing the twelve houses, in which are marked the situation of the heavens and stars, in order to form predictions. HoRoscoPE Lunar, the point from which the moon proceeds when the sun is in the ascending point of the east. HORS DE CoMBAT, a term in use in the French army, to express the total loss to an army by a battle, including killed, wounded, prisoners and deserters. - HoRs de Son Fee, an exception to avoid an action brought for rent issuing out of certain lands, by him that pretends to be the lord, or for some custom and services; for if the de- fendant can prove the land to be without the compass of his fee, the action fails. PHORSE, a rope reaching from the middle of a yard to its arms or extremities, and depending about two or three feet under the yard, for the sailors to tread on while they are loos- ing, reefing, or furling, the sail; rigging out the studding sail booms, &c. In order to keep the horse more parallel to thé yard, it is usually attached thereto at proper distances, by cer- tain ropes called stirrups, which hang to their lower ends, through which the horse passes. HoRSE, signifies also a thick rope, fixed perpendicularly fore or aft a mast, for the purpose of hoisting some yard. - The HoRSE is distinguished from every other quadruped, by having his hoofs single, and his tail eovered with long hair. The male has the name of horse, the female of mare, and the young one of foal. Wild horses are found in large herds in Siberia, and several other parts of Asia, as well as 1n some parts of Africa. Endowed with the most useful qualifications, the horse is an animal of the greatest importance to the imha- bitants of all temperate climates. Though naturally spirited, active, and intrepid, he submits with patience to carry burdens, and to toil for days together along the roads and in agricultural labours; and, if treated with care and attention, he persever- ingly adapts himself to our wants and conveniences. In some parts of Tartary, these animals have even been made objects of divine worship, originating no doubt in a principle of grati- tude for the services they perform. By the Arabians, they are nearly as much attended to and beloved as human beings; liv- ing in the same tents with their owners, and participating in | all the kindnesses which they bestow upon their own families. In Arabia, indeed, these animals may be deemed the chief sup- port of the families who possess them ; and (surrounded with foes) the very existence of the owner not unfrequently depends wpon the powers of his horse. , - . . . In no country of Europe is so much attention paid te the breeding and training of horses as in England. The conse- quence has been, that the British horses are superior both in swiftness of foot, and in strength and perseverance in the course, to any others in this quarter of the world. - The fleetest of all the British horses is of course the race- horse; and, for short distances, none of the Arabians which have been tried in England have proved in any degree, equal to him. The celebrated horse, called Childers, in the year 1721, ran four miles in six minutes and forty-eight seconds, car- rying a weight of nine stone two pounds. Had the different racing meetings at Newmarket, York, and other places, no other view than to call together great concourses of people for amusement, their tendency would be injurious rather than beneficial to society ; but when it is considered that such meet- ing are the cause of great emulation in the breeding of a race of animals so valuable as the horse, their utility will be suffi- ciently apparent. - - - The English hunters are allowed to be among the noblest, most elegant, and most useful animals that are known; and the value of our hackneys or road horses may be imagined, when it is stated that many of them are able to trot at the rate of more than fifteen miles per hour. In the year 1746 the post- master of Stretton is stated to have ridden on different horses along the road to and from London, no fewer than 215 miles in eleven hours and a half, which is at the rate of above eighteen miles an hour. - So great is the strength of these anim is, that instances have been mentioned of a single horse drawing, for a short space, the weight of three tons; and of others carrying a load which weighed more than 900 pounds. The immense dray-horses which are employed by the brewers, and are so frequently seen in the streets of London, though in some measure useful | as being able better to sustain the shock of loading and unload- ing than slighter animals, are chiefly kept from a principle of ostentation. The British draught-horses are extremely valuable animals, but particularly a chesnut-coloured race called Suf- folk horses. • . - - In Scotland therc is a breed of small horses or ponies, which are known by the name of galloways The best of these seldom exceed the height of fourteen hands and a half,” and are extremely active, hardy, and spirited animals. The Shetland islands produce a race called shelties, which, though exceedingly diminutive in size, are in other respects highly excellent. . In Ireland, the cart-horses, though of sufficient size, are ill- shaped and bad. The saddle-horses appear naturally as goo'. as ours; but in general they are still worse shod. - - There is a prevalent and erroneous notion, that the flesh of the horse is bitter and unpalatable. In several parts of Asia wild horses are killed almost exclusively for food; and the Calmuc Tartars, in particular, are so partial to this kind of Wºr ill kept, worse groomed, and t” Four inches make a hand. This is the usual mode of estimating the height of horses. 6 B 462 *H O R. H o R DICTIONARY OF MECHANICAL SCIENCE, flesh, that they seldom eat any other. Horses' flesh is con- stantly exposed for sale in the markets of Tonquin. A cele- brated British writer (Dr. Anderson) has strongly recommended the fattening of horses as food in this country, and urges his recommendation by declaring that horse-flesh is superior in delicacy of flavour to beef! * The Tartars drink the milk of the mare, and also convert it into butter and cheese. One of their most favourite kinds of beverage is called koumiss, which is a sort of wine made of fer- mented mares' milk; and is carried by them from place to place, in bags made of horses' hides. When in perfection, the taste of koumiss is said to be a pleasant mixture of sweet and sour; but it is necessary to agitate it before it is drank. This preparation is also considered of great utility in a medicinal V16. W. The skin of the horse, after it is tanned, is made into collars, .races, and other parts of harness; and under the name of cordovan is also used for shoes. The hair forms a considerable branch of trade. That of the tail is employed for weaving the covers or seats of chairs and sofas; for making sieves, fishing- lines, and.the bows of musical instruments. The inferior hair of the tail and mane is employed for the stuffing of bolsters and mattresses. For this purpose it is baked, which renders it one of the most elastic substances for couches that are known. The short hair of the horse is used for stuffing sad- dles and horse-collars. If horses be well treated and properly attended to, they will sometimes live to the age of fifty years; but during a great part of this time, they are generally so decrepit as to be un- able to perform any services whatever for their owners. To ascertain the age of a horse, reference is generally had to the teeth. Every treatise on farriery has in- structed us to know a horse's age by the mark in his mouth; but not one in five hundred (a dealer excepted) can retain it in his mind...We have endeavoured, therefore, to represent it by engravings. º - Every horse has six teeth before in each jaw : . till he is two years and a half old, they are all smooth and uniform in their Fig. 2. ' upper surfaces, fig, 1. At two tº ºf e years and a half old he sheds the two middle teeth (by the young teeth’s rising and forcing the old ones out, as at fig. 2,) which at three years old are replaced by two hollow ones, as at fig. 3. When he is about three years and a half old, he sheds two others, one on each side the two middle ones, fig. 4, which at four years old are replaced by two others, which are also hol- low, as at fig. 5. The sharp single teeth in horses, (fig. 4.) begin to appear in the lower jaw when the horse is about three years and a half or four years old. when he is nearly six years old, they are full grown, pointed, and concave in the in- side, as at fig. 5. When he is four years and a half old, he sheds the two corner teeth, fig. 6, which at five are replaced also with two hollow ones, grooved on the inside, as at fig. 7, which groove marks the age precisely. At six years of age this groove begins to fill up, and disappear, as at fig. 8, so do the hollows of the rest of the teeth, which continue till near seven and a half or eight years old, when all the teeth become uniformly full and smooth, as at fig. 9. Crafty jockeys will sometimes burn holes in the teeth, to make them appear young, which they call bishoping; but a discerning eye will soon dis- cover the cheat. - § sº # * * s = s: à By inspecting the eyes also, we may know the condition of a horse, especially as to sight: thus, if a horse's eyes are lively and clear, and you can see to the bottom, and the image of your face be reflected from thence, and not from the surface of the eye, they are good; but if muddy, cloudy, or coal-black, they are bad. . . With respect to his legs, you ought to observe whether his knees are broken, or stand bending and trembling forward; if so, the animal is unsound; if he steps short, and digs his toes in the ground, it is a sign he will knuckle. In short, if the hoof be pretty flat and not curled, you need not fear a founder. As to his wind, if his flanks beat even and slow, his wind may be good, but if they heave double and irregular, or if (while he stands in the stable) he blows at the nostrils, as if he had just been galloping, they are signs of a broken wind. Deceitful dealers have a draught which they sometimes give, to make a horse breathe regularly in the stable; the surest way therefore to judge of his wind, is, to give him a good brushing gallop, and it is ten to one, if his wind be broken, or even touched, that he will cough and wheeze very much, and no medicine can prevent his doing so. In buying a horse, inquire whether he bites, kicks, stops, and starts; for a horse may be perfectly sound, and yet guilty of these four vices. And a good sound horse has neither splint, spavin, nor windgall, which are excrescences and swellings about the legs. But this ..] is not a treatise on farriery. Shoeing of Horses.—The shoes should be made three times as thick at the toe as at the heels, so that by this means the frog may come down to the ground. The nails are all placed forward, four on each side, but not approaching too near the heels. They should be counter-sunk in conical or wedge- shaped holes. For horses which go in shafts, or are used in hunting, it is usual to make shoes with only one heel, which should be outward. The horse’s heel must be rather lowered on that side, and the inner heel of the shoe somewhat thickened, so as to balance and bear equally. The best breadth for the shoe of a medium-sized horse is said to be one inch at the toe, and three-quarters at the heel; the weight about eighteen or twenty ounces. In order to fit the shoe without causing the horse to stand too much on his heels, the under part of the crust, or wall of the hoof, is pared away to receive the excess of thickness in front; for the bottom of the shoe ought to be perfectly flat, without any stubs or calkings in front. Paring away the heels is a most destructive practise, except in case of absolute excrescence in those parts: nor should the bars, (or diagonal ridges) that extend from the heels to the frog, or central projection, ever be cut more than is absolutely proper for the purpose of keeping them in a clean and healthy state. A good open heel is the indication of a powerful foot; hence the sides of shoes ought not to be much contracted. When the heels are tender, what is called a bar-shoe ought to be applied. On the frog the horse chiefly depends for a spring, or resistance at the bottom of his foot. If this part does not touch the ground, the whole motion will be derived from the upper parts of the limb, and a very uneasy gait will inevitably follow. This points out the necessity for leaving it fully at liberty to come in contact with the ground. Horse Dealers. Every person exercising the trade or busi- ness of a horse-dealer, must take out a license, from the Stamp-office. Horse-dealers carrying on business without a license, are liable to be assessed the duties on riding horses. HoRses. It is lawful for any person to transport. by way of merchandise, horses into any parts beyond the seas in amity with his majesty, paying for each 5s. No person convicted of feloniously stealing a horse, shall have the privilege of clergy; accessaries before or after, are also deprived of the benefit of their clergy. If a horse be stolen out of the stable, or other curtilage of a dwelling-house, in the night time, it falls under the denomination of burglary; if in the day-time, it falls under the denomination of larceny from the house. Keepers of slaughter-houses for horses, are subject to regulations enacted by an act of 26 Geo. III. c. 74. If any person shall unlawfully and maliciously kill, maim, or wound any cattle, every person so offending, shall be adjudged guilty of felony. If a horse, or other goods, be delivered to an innkeeper, or his servants, he is bound to keep them safely, and restore them when his guest H Q S H O U 463 DICTIONARY OF MECHANICAL SCIENCE. leaves the house. If a horse be delivered to an agisting far- mer for the purpose of depasturing in his meadows, he is answerable for the loss of the horse, if it be occasioned by the ordinary neglect of himself or his servants. If a man ride to an inn where his horse has eat, the host may detain the horse till he be satisfied for the eating. - HORTUS SICCUS, or DRY GARDEN, is an appellation given to a collection of specimens of plants, carefully dried and preserved. Plants may be dried by pressing in a box of sand, or with a hot smoothing iron; and each of these methods has its advantages. If pressure be employed, a couple of boards, about 18 inches long, 12 broad, and 2 thick, with screws at each corner and nuts on them, something like a bookbinder's press, will do very well; or the plants may be put between the leaves of a blotting paper book made en pur- pose, and weights laid on the book till the plants are dried. Next, some quires of unsized blossom blotting paper must be provided. The specimens, when taken out of the tin box, must be carefully spread on a piece of pasteboard, covered with a single sheet of the blossom paper quite dry; then place three or four sheets of the same paper above the plant, to imbibe the moisture as it is, pressed out; it is then to be put into the press. As many plants as the press will hold may be piled up in this manner. At first they ought to be pressed gently. After being pressed for twenty-four hours or so, the plants ought to be examined, that any leaves or petals which have been folded may be spread out, and dry sheets of paper laid over them. They may now be replaced in the press, and a greater degree of pressure applied. The press ought to stand near the fire, or in the sunshine. After remaining two days in this situation, they should be again examined, and dry sheets of paper be laid over them. The pressure then ought to be considerably increased. After remaining three days longer in the press, the plants may be taken out, and such as are suffi- ciently dry may be put in a dry sheet of writing-paper. Those plants which are succulent may require more pressure, and the blossom paper again renewed. Plants which dry very quick, ought to be pressed with considerable force when first put in the press; and, if delicate, the blossom paper should be changed every day. When the stem is woody, it may be thinned with a knife, and if the flower be thick or globular, as the thistle, one side may be cut away; as all that is necessary in a specimen, is to preserve the character of the class, order, genus, and species. Plants may be dried in a box of sand in a more expeditious manner; and this method preserves the colour of some plants better. The specimens, after being pressed for ten or twelve hours, must be laid within a sheet of blossom paper. The box must contain an inch deep of fine dry sand, on which the sheet is to be placed, and then covered with sand an inch thick: another sheet then may be deposited in the same manner, and so on, till the box be full. The box must be placed near a fire for two or three days. Then the sand must be carefully removed, and the plants examined. If not sufficiently dried, they may again be replaced in the same manner for a day or two. In drying plants with a hot smooth- ing iron, they must be placed within several sheets of blotting paper, and ironed till they become sufficiently dry. This method answers best for drying succulent and mucilaginous plants. When properly dried, the specimens should be placed in sheets of writing-paper, and may he slightly fastened by making the top and bottom of the stalk pass through a slip of paper, cut neatly for the purpose. Then the name of the genus and species should be written down, the place where it was found, nature of the soil, and season of the year. These specimens may be collected into genera, orders, and classes, and titled and preserved in a portfolio or cabinet. HOSPITAL, WILLIAM FRANCIs ANto NY, MARQUIs De L”, a celebrated French mathematician, was born of an ancient family in 1661. He was a geometrician almost from his infan- cy; for one day being at the Duke of Rohan's where some able mathematicians were speaking of a problem of Pascal’s, which appeared to them extremely difficult, he ventured to say that he believed he could solve it; in a few days he sent them the , solution. He entered early into the army, and was a captain of horse ; but being extremely short-sighted, and exposed on that account to perpetual inconveniences and errors, he at of the aged, infirm, and helpless. ancient, and the benefits resulting from it are incalculable. In London alone, and its suburbs, there are upwards of thirty hospitals; some bearing a name corresponding with the dis- eases for the cure of which they were established, and others taking their appellation from the place in which they stand, or length, quitted the army, and applied himself entirely to his favourite amusement. He contracted a friendship with Mal- branche, and took his opinion upon all occasions. In 1693 he was received an honorary member of the Academy of Sci- ences at Paris; and soon after published a work upon Sir Isaac Newton’s Analysis. & - Hospital, a place or building, erected, endowed, or sup- ported, by charitable contributions, for the reception and relief The institution is very the means by which they are supported. Many among them are amply endowed, but the rules and regulations by which they are governed, are too voluminous and diversified to be given in detail. - - w *. HOT-Beds, in Gardening, beds made with fresh horse- dung, or tanner's bark, and covered with glasses to defend them from cold winds. According to the quantity and quality of the materials put together for hot-beds, the heat will be porportioned as to strength and duration. The place where hot-beds are worked should be open to the full sun, and be screened from the north and north-east winds. Working of . the dung is necessary previous to the making of a hot-bed, i.e. it should be thrown together on a heap, in a conical form; and when it has taken a thorough heat, it should be turned over, moving the outside in, or mixing the colder parts with the hot. When it has taken heat again for two or three days, give it a second turn as before, and having lain the same time, it will be in proper order for making a good lasting bed with a steady heat. Hot-House, an erection warmed by means of flues, for the culture of tender exotics of tropical climates. The site of a hot-house is extremely important. A south-west aspect is to be preferred. * HOUNDS, in sea-faring language, are those parts of a mast head which gradually project on the right and left side beyond the cylindrical or conical surface. These hounds, support the frame of the top, together with the topmast and the rigging of the lower-mast. HOUR, is the twenty-fourth part of a natural day. Different people reckon the hours in a different manner. Babylonish hours are those which are counted from sun-rising in a con- tinued series of twenty-four. European hours are those counted from midnight, twelve from thence to noon, and from noon to midnight twelve more. Those which commence their order from noon are called astronomical, because used by astronomers. The Jews, Chaldeans, Arabs, and other eastern people, divide their hours into a thousand and eighty scruples, eighteen whereof are equal to our minute. --> HOUSE, in Astrology, denotes the twelfth part of the heavens. House, the common dwelling of man in civilized society. We shall, under this definition, consider the several parts of which a building for our accommodation is composed. The article will necessarily include all those particulars deserving of notice to the bricklayer, the mason, the carpenter, and pro- prietor or occupier of a house. - I. Brichmaking, &c.—The art of bricklaying or building with bricks is of great antiquity, and appears to be coeval with the earliest edifices on record. The making of bricks for building has been variously practised among different nations. The Babylonians often impressed or engraved inscriptions on their bricks in a character which has given rise to much discus- sion among the learned. The ancient Greeks chiefly used three kinds of bricks; bricks of two or three palms in length, those of four palms, and those of five palms. The Romans, from a comparative deficiency of marble, built more with bricks than the Greeks, and employed the arch, and the vault, to which this useful material so much contributed, more than their predecessors. Their bricks, according to the authority of Pliny, were about seventeen inches long, and eleven broad, and scarcely thicker than our paving bricks. Palladio, Sir Christopher Wren, and other eminent modern architects, have constructed beautiful and well-proportioned edifices in brick. Bricks, as manufactured in England, are always burned or 464 H O U H O U. DICTIONARY OF MECHANICAL scIENCE baked. Unburnt bricks, after the ancient mode, are still in use in Egypt, and many parts of the East. The modes of making bricks in Great Britain are various: those manufac- tured in the country differ from those made in the neighbour- hood of the metropolis, and are distinguished by their colour; the former being a deep red, and the latter a yellow, stone colour, and gray. The country bricks, which are baked in a kiln, are made of a stronger earth, and have no internal firing; but the London method is beginning to be adopted near all large towns, both in England and in Ireland, where cinders and coal ashes can be procured, and by far the greatest quan- tity of bricks are now made in that manner. On comparing the strength and durability of modern bricks with those of ancient times, it is evident that the former are in every respect inferior. The ancients selected the best sort of clay, and combined it with other ingredients well adapted to improve its properties. In the southern provinces of Russia, in the stupendous Tartary mountains, bricks which scarcely yield to the hammer, owe their excellence to the ancients burning them uniformly, after they had been thoroughly dried. No doubt can be entertained, that if modern brickmakers were to pay more attention to their art, by digging the clay at pro- per seasons, exposing it much longer to the air than is done at present, working it sufficiently, bestowing more care upon the burning of the bricks, and that the latter operation may be done uniformly, making them much thinner than is prescribed by the standard form, we should be provided with bricks equal in point of strength and durability to the best of former times. In a variety of instances, persons may have it in their power to obviate some of these causes of defect, and it is therefore properto mention them; but the state of society is not favour- able to any general change in the system which brickmakers pursue; the expedition with which a given number of bricks can be furnished, and the cheapness of the rate at which they can be manufactured, are to them the primary objects of con- sideration; and the speculative builder cares little about the real value and durability of his edifice, provided the diſference between the cost and sale price is sufficiently ample to recom- pense him to his satisfaction. - It is an erroneous notion that bricks may be made of any earth that is not stony, or even of sea ooze ; too much sand entering into their composition, renders them heavy and brittle, and too much fat argillaceous matter causes them to crack in drying: those only will burn red which contain iron particles. In England they are chiefly made of a motley, yellowish, or somewhat reddish fat clayey earth, commonly called loam. Those of Stourbridge clay, and Windsor loam, are esteemed the most proper and durable bricks, and they will stand very high degrees of heat without melting. The common potter's clay, which is also employed in the manufacture of bricks, is found to consist of thirty-seven parts of pure argillaceous or clayey earth, and sixty-three parts of siliceous or flinty earth. Of whatever description the earth intended for bricks may be, it ought to be dug between the beginning of July and the latter end of October, before the first frost appears; it should be repeatedly worked with the spade during the winter, and not formed into bricks till the following spring. If the earth were not used till two or three years after it had been dug, the quality of the bricks would be materially improved; and in all cases, the oftener it is turned, and the more completely it is in- corporated, the better will be the bricks. The clay, before it is put into pits for soaking, must be broken as small as possible, and allowed to lie at least ten days; every stratum of twelve inches should be covered with water, in order that it may be uniformly softened. Two pits, at least, will be necessary for every brick manufactory, so that, after having been suffered to remain for five days, the second may be prepared, and thus the manufacture carried on without interruption. The earth should as much as possible be divested of stony particles, and other extraneous matter, and should have sufficient time to mellow and ferment, other- wise it will be difficult to temper. On the treading and temper- ing, twice the customary quantity of labour ought to be be- stowed. Much of the goodness of bricks depends upon the proper management of its first preparation, for the earth itself, previous to its bein" wrought possesses very little tenacity; but by long exposure to the air and frost, and thoroughly work- ing and incorporating it together, it is converted into a tough, M. gluey substance, in which state alone it is fit for moulding. . In the vicinity of London, coal ashes, and in other parts of: the country, light sandy earth, is usually mixed with the clay, which, with such addition, is more easily and expeditiously. wrought, and requiring rather less fuel, occasions some saving in the expense of burning the bricks; but here the advantages of it terminate; in other respects it is injurious rather than. otherwise. If, in tempering the earth, too much water be used, the bricks become dry and brittle; but if duly tempered, they will be smooth, solid, hard, and durable. . A brick properly made, requires nearly as much earth as a brick and a half. made in the common way, when too great a proportion of water has been added, which tends to render the bricks spongy, light, and full of flaws. As bricks made in the best manner are more solid and ponderous than the common ones, they require a much longer time to dry; they ought not to be burnt till they will give a hollow sound on collision. Proper attention to the drying of bricks is necessary to prevent their cracking and crumbling in the kiln. - • , Of whatever materials the kiln be constructed, each burning of from six to ten thousand bricks requires the fire to be kept up at least for twenty-four hours, and double that time for a number of from twe’ve to fifty thousand. . The uniform increase of heat deserves particular attention; its duration should be regulated according to the season: in cold weather fire burns most fiercely. During the last twenty-four hours the fire should be uninterruptedly supported by means of flues, but afterwards the fire should not be suddenly closed, as there is always some danger of bursting the flues or melting the bricks. g - The following experiment, by Gallon, made with a view to ascertain the difference in the quality of bricks differently manufactured, deserves to be generally known. A certain quantity of the earth prepared for moulding into bricks was taken for the experiment; at the end of seven hours, it was moistened and beaten for the space of thirty minutes. The next morning the same operation was repeated for an equal length of time ; in the afternoon it was again beaten for fifteen minutes. Thus this earth had not only been worked for an hour and a quarter longer than usual, but at three different times; the consequence was, that its density was increased; for a brick made of it weighed five pounds eleven ounces, while another brick made in the same mould, of the earth that had not received this preparation, weighed only five pounds seven ounces. The two sorts of bricks were dried in the air, for the space of thirteen days; they were then burnt with others, with- out any particular precautions, and when they were taken from the kiln, it was found that the bricks made of the earth which had been most worked, still weighed four ounces more than the others, each having lost five ounces by the evaporation of the moisture. They differed also very remarkably in strength; for on placing them with the centre on a sharp edge, and load- ing the two ends, the bricks formed with the well-tempered earth were not broken with a less weight than sixty-five pounds, or one hundred and thirty pounds in all; while the others were broken with thirty-five pounds at each end, or seventy pounds in the whole. That the quality of bricks should be improved, by bestowing more labour upon the preparation of the earth, will hardly excite surprise, though the degree of the improve- ment, as just stated, may certainly be considered remarkable; but there is another mode of strengthening these artificial stones, still more extraordinary, and not so easily to be accounted for. Goldham observes, that bricks which have been once burnt, then steeped in water, and burnt again, become doubly strong. We know not that this observation, which is repeated without comment, by nearly all the writers who have occasion to treat of this subject, will always be veri- fied in practice; but it deserves attention, from the number and respectability of the writers who have contributed to give it currency. The following is a description of the best method of making bricks, with all the improvements that have been introduced within the last few years. The earth most proper for making the country or kiln-burnt H O U H O U , 465 DICTIONARY OF MECHANICAL SCIENC p. bricks, which, from containing ferruginous particles, always. burn red, is a stiff clay, which is tempered alone, formed in moulds, dried in the air and sun, and baked in a kiln like pot- tery. These sort of bricks are hard and red, sometimes with dark gray or black ends, which, as often seen in our villages, the country bricklayers dispose in various figures of dates, chequer work, and similar forms. They are unfit for cutting and rubbing for gauged work, which is always performed with a milder sort, called red rubbers. The earth selected as the most fit for making common bricks after the London mode, is a clayey loam ; and that for the superior sort, such as those which are used for facing build- ings, called malm stock bricks, is a lighter sort of loam, in which marl is found, frequently met with from two to three feet below the clayey loam. - - The earth having been dug in autumn, the workmen are to be employed during the winter in preparing it for the ensuing season. This is done by removing the vegetable mould from the surface, which is called uncallowing, and placing coal ashes in proportion of two inches in thickness to every foot deep of earth, which is twelve chaldron of coal ashe, or bereze, as it is called, to every hundred thousand of bricks, and mixing them together in digging the earth; because the composition is improved in proportion as it is exposed and acted upon by the frost, rain, and wind. The mixture is then generally turned over once after it has been dug, but is seldom suffered to remain in this state of preparation longer than one winter before it is used, as it would be inconvenient to the manufac- turer from the space it thus occupies; and it is considered not to improve the earth so much as it deteriorates the combustible qualities of the ashes. When the prepared soil has thus endured a winter's prepa- ration, it is delivered over about Lady-day to the charge of the brickmaker, or moulder, as he is called ; and the first thing to be attended to in the formation of sound bricks, is temper- ing the earth. This was formerly done by a gang of six per- sons, employed and paid by the moulder, who makes them from the heap till laid on the hack to dry by the thousand; and an active, industrious, skilful man can, with these assistants, who are often his wife and children, mould from six to seven thousand in a day, calculating from five o'clock in the morning till eight at night. One of this gang tempered and prepared the earth with a long hoe, by which he pulled it from the heap; a shovel, with which he chopped it backwards and forwards, turning it as often as he found it necessary, incorporating the ashes, sand, and earth thoroughly together; and a wooden scoop, with which he threw water over the mass in preparation, to bring it to a more ductile state. The great difficulty of having this operation, on which so much of the success of the manufacture depends, well performed, has occasioned the introduction into extensive works of machines called pug-mills, into which the prepared earth is wheeled after it is mixed with a proper quantity of water. Care should be taken, whether the tempering be done by men or the mill, that too much water be not used, as the more solid the brick is delivered from the mould, the better it retains its form on the hack where it is set to dry ; the less it shrinks in drying, the sooner it dries, and the better and more shapely it burns. - When the mass is sufficiently mixed, by either of the above modes, it is laid in small parcels, well kneaded, on the mould- ing table, which is covered with dry sand. The moulder throws it smartly into the mould, presses it down to fill all the :cavity, and strikes off the overplus with a stick, previously dipped in water. He then turns the newly formed brick from the mould on to a thin board, larger than the brick, which is removed by a boy to a light latticed wheelbarrow, and is thus conveyed, covered slightly with fine dry sand, to the hacks to dry. The bricks are arranged on the hacks with great regula- rity one above the other, a little diagonally, in order to give a free passage to the air. In showery weather the piles are rusually protected from its injurious effects by some cheap covering, such as straw, or old light boards. In grounds not very extensive, sheds are sometimes erected. When the bricks are sufficiently dried in the hack, which in fine weather may be in about mine or ten days, they are ready for the fire, which completes the operation. It is of the great- est consequence to the quality of the bricks, that they should be thoroughly dry before they are set in the clamp or stack, which can only be ascertained by breaking a few in halves. selected from various parts of the hack. If the operation of drying in the hack be not thoroughly performed, the bricks will never burn sound; and the moisture which ascends from them in the form of vapour, renders the upper courses in the clamp peculiarly unsound. - - . The clamps are generally of an oblong form, and contain from one hundred thousand to half a million of bricks. The thickness of the walls should at least be a brick and a half. Bricks are burned in kilns with less fuel, and with greater uni- formity and expedition, than in clamps. When they have been set or placed in the kiln, they are covered with pieces of bricks or tiles, and dried by kindling a gentle fire, which is kept up for two or three days, or till the smoke becomes light, More fuel is then added, and the mouth or mouths of the kiln are nearly closed with bricks and wet clay; as soon as the arches of the kiln look white, and the fire begins to appear at the top, they slacken the heat for an hour, and let all cool by degrees. This they continue to do, alternately heating and slacking, till the bricks are thoroughly burnt, which is usually effected in forty-eight hours. The stacks or clamps are built of the bricks themselves. The foundation is commonly somewhat raised from the sur- rounding ground, and of an oblong form; the sides slant inwards a little towards the top ; hence the clamp, in its figure, is a truncated pyramid. Flues, about the length of a brick in breadth, are made entirely through the clamp; they are about six feet apart when the burning is to be hastened, otherwise they are made about nine feet from each other. The arching of the flues is performed by laying the successive layers of bricks a little over the edge of those below them, till they nearly meet, and then a binding brick at the top finishes the arch. In every direction, the bricks are separated from each other by a stratum of coals and cinders. To facilitate setting fire to the clamp, a quantity of wood is laid with the coal in the ſlues. When the fire is kindled, if it burn strongly, or the weather is precarious, they plaster the outsides of the clamp with clay, and close the apertures of the flues. On the top of the clamp, a thick layer of breese (cinders) are uniformly laid. When the whole of the fuel is consumed, the manufacturer concludes that the bricks are sufficiently burnt. The opera- tion requires from twenty to thirty days, according to the quantity of fuel, the proximity of the flues, and the state of the weather. When the process has been properly conducted, those in the interior of the clamp are hard, square, and of a good bright colour. These are the stock bricks of the London market. The preparation of the loam, marl, ooze, chalk, &c. with which the beautiful yellow malm stock of London, and the pale bricks of the Ipswich sort, are made, requires more attention, and a longer and more careful process. The earth and other ingredients with which the soil for malm, bricks are composed, are wheeled into a mill with a due proportion of water. This composition is then ground in the raill, which is supplied with two sets of knives and harrows, and runs out in a state of thick mud or sludge through wooden spouts, into hacks which are raised near the mill. It is there left, till by the water soaking away, and by absorption, it acquires a sufficient consistency or solidity to be kneaded for the moulder. The moulding, drying on the hacks, and burning in the clamps, is performed exactly as before described for common stocks, but with more care and precaution. As marl is not always to be found where malm stock bricks are required, the method used by Mr. Lee, of Lewisham, is so good a substitute, that it is worthy the attention of build- ers, who may wish to manufacture these beautiful bricks with- out marl. After many experiments, occasioned by the paucity of marl in the London districts, Mr. Lee discovered that chalk, mixed in certain proportions with the loam, and treated in the usual manner, produced an excellent substitute. For this discovery he took out a patent, which having now expired, this mode of mixing a small quantity of chalk with the brick earth, is generally adopted round London, for the purpose of giving colour and soundness to the brick. At Emsworth, in Hamp- 6 C - ... 3 , - . º 466 H O U H O U DICTIONARY OF MECHANICAL SCIENCE. shire, and at Southampton, ooze or sludge from the sea shore, which contains much saline matter, is used for a similar pur- pose; but however sound these bricks are, they have neither the rich brimstone colour of the London malm stock, nor the regular stone-coloured creamy hue of the Ipswich bricks. #3ricks, like most other useful articles in this country, are subject to a duty, and form an important part of the annual revenue of the government. They are also subject to a regu- lation as to size. By the 17th Geo. III. cap. 42, all bricks made for sale, shall, when burned, be not less than eight and a half inches long, four wide, and two and a half thick; and by 43 Geo. III. cap. 69, which consolidated the excise duties, every thousand bricks made in Great Britain, not exceeding ten inches long, three inches thick, and five inches wide, are Iiable to a duty of five shillings; and exceeding these dimen- sions, to ten shillings. . The principal bricks used in the United Kingdom, are stock and place bricks, from the stock brick clamp: malm stocks, cut- ters, seconds, and pavers, from the malm clamp. Red stocks, paving bricks, fire bricks, foot and ten-inch tiles, from strong clay, and burned in a kiln. Of the fire bricks, the best are from Windsor, Stourbridge, Wales, and some of the iron counties. The Welsh are excellent, and will stand extreme heat; they are made of large sizes for the boilers of sugar-houses, brewers’ eoppers, &c. and are called Welsh lumps. The place bricks and stocks are used in common walling ; the marls are made in the neighbourhood of London; these are very beautiful bricks, of a fine yellow colour, hard, and well burnt, and in every respect superior to the stocks. The finest kind of marl and red bricks are called cutting bricks; they are used in the arches over windows and doors, being rubbed to a cen- tre, and gauged to a height. An acre of land, including the ashes mixed with the earth, is computed to yield about one million of bricks for every foot in depth. The brick mould is ten inches in length, and three in breadth, and the finished bricks are about nine inches long, four and a half broad, and two, and a half thick. Different qualities of earth, however, produce bricks of different dimen- sions from the same mould ; and even the same earth, in pro- portion as it is more or less wrought or burnt, exhibits similar results. It is extremely probable that bricks, properly made, would prove superior in durability to almost every kind of stone. In Holland, the streets are every where paved with a hard kind of bricks, known by us under the name of clinkers, which are often imported into this country, and used for paving stables and court yards; and houses in Amsterdam, which have stood more than two centuries, so far from being decayed, appear perfectly fresh as if new. - The numerous patents which have been granted for the making of bricks, appear to have had improvements in the formation of the article for their principal object, without much regard to the materials of which it is composed. Cartwright's patent, the exclusive privilege conferred by which has now expired, is perhaps one of the most important. His improve- ment consists in giving bricks such a shape or form that they shall mutually lock or cramp each other. The principle of his invention may be understood, by supposing the two opposite sides of a common brick to have a groove or rabbet down the middle, a little more than half the width of the side of the brick in which it is made ; there will then be left a shoulder on each side of the groove, each of which shoulders will be nearly equal to one quarter of the width of the side of the brick, or to one-half of the groove or rabbet. A course of these bricks being laid shoulder to shoulder, they will form an indented line of nearly equal divisions; the grooves or rabbets being somewhat wider than the two adjoining shoulders, to allow for mortar, &c. When the next course comes on, the shoulders of the bricks which compose it, will fall into the grooves of the first course ; and the shoulders of the first course will fit into the grooves or rabbets of the second, and so on. This configuration of the bricks is to be preferred, as it is perfectly simple; but the principle will be preserved by whatever form of indenture they lock or cramp each other. For the purpose of turning the angles, it may be expedient to have bricks of such a size and shape as to correspond with in the common mode. each wall respectively, though this is not absolutely necessary, as the grooves in the bricks of each wall, where they cross or meet each other, may be levelled, and the bricks lap over as For the purpose of breaking the joints in the depth of the wall, bricks will be required of different lengths, though of the same width. Buildings constructed with bricks of this principle, will require no bond timber, one universal bond running through and connecting the whole building together; the walls of which can neither crack nor bulge out, without breaking through the bricks themselves. When bricks of this form are used for the construction of arches, the sides of the grooves or rabbets, and the shoulders, should be the radii of the circle of which the intended arch is to be the segment. In forming an arch, the bricks must be coursed across the centre on which the arch is turned, and a grooved side of the bricks must face the workman. It may be expedient, though not absolutely necessary, in laying the first two or three courses at least, to begin at the crown and work downwards. The bricks may be either laid in mortar, or dry, and the interstices afterwards filled and wedged up, by pouring in lime putty, plaster of Paris, grouting, or any other convenient material, at the discretion of the workman or builder. Arches on this principle, it is stated, having no lateral pressure, can neither expand at the foot, nor spring at the crown, consequently they will want no abutments, requir- ing only perpendicular walls to be let into, or to rest upon; and they will want no incumbent weight upon the crown to prevent their springing up, a circumstance often of great im- portance in the construction of bridges: Anothér advantage attending this mode of arching is, that the centres may be struck immediately; so that the same centre (which in no case need be many feet wide, whatever may be the breadth of the arch) may be regularly shifted as the work proceeds. But the greatest and most striking advantage attending this invention, is the absolute security it affords (and at a very reasonable rate) against the possibility of fire; for, from the peculiar pro- perties of this arch, requiring no abutments, it may be laid upon, or let into, common walls, no stronger than what are required for timbers, of which, precluding the necessity, it saves the expense. A more particular account of this inven- tion, illustrated by two plates, may be seen in the third volume of the “Repertory of Arts and Manufactures.” ; In 1798, Francis Farquharson, of Birmingham, obtained a patent for making bricks and tiles by machinery; and indeed the use of horse power, in working the clay, is now very COBalmOn. . - • Whitmore Davis, of Castle Comber, in the county of Kilkenny, Ireland, observed some persons in the vicinity of a colliery, to employ a mortar, for the backs of their grates, which in a short time became very hard. This substance he found, on inquiry, to be what miners term seat-coal, or that fossil . which lies between coal and the rock. It has been examined by Kirwan, who is of opinion that it will, when mixed with a due proportion of clay, produce a kind of bricks, capable of resisting the action of fire, and conse- quently well calculated for furnaces, or similar structures. The discovery of the use of this substance is considered im- portant, and it is further observed, that seat-coal, properly prepared, will answer every purpose of tarras, for buildings beneath water. In building, a considerable waste of time arises from the necessity of making bricks less than the common size, to suit particular situations. Nor is the waste of time the sole loss; in attempting to divide a brick, especially in the direction of its length, one half of it is generally reduced to useless splin- ters ; but bricks have lately been made, which in their soft state were nearly cut through by pressing a wire upon them; they can then be divided by a single blow: a proportion of them, along with the common sort, produces on the whole a saving of some moment. * It is of considerable importance to examine clay before it is made into bricks, in order to ascertain whether any addition can be made to it which will improve its quality. According to the observation of Bergman, the proportion of sand to be used with any clay, must be greater, the more such clay is found to contract in burning, but the best clays are such as H O U H O U 467 DictionARY of MechANIcAL scIENCE. require no sand. This illustrious chemist recommends the following mode of analysis to manufacturers: Nitric acid poured upon unburned clay, detects the presence of lime, by producing an effervescence. Calcareous clays, or marls, are often the fittest materials for making bricks. In the next place, a lump of clay, of a given weight, is to be diffused in water by agitation. The sand will subside, and the clay remain suspended. - Paving tiles are a long flat kind of brick, used for laying the floors of kitchens, dairies, cellars, &c. sizes of them are generally made: the least of English manu- facture are about the same length and breadth as common bricks; the largest are about twelve inches square; a middle size, about mine inches square, is also in common use. The thickness of all the sizes of paving tiles is only about an inch and a half. They are made of the strongest kind of clay, and well burnt. Paving tiles or bricks look the best when laid diagonally. The most common tiles for roofs are those called pan tiles, which are thirteen inches long and eight broad, and about half an inch thick; they are curved in the direction of their length, so that their transverse section is a figure of contrary curvature, like the letter on ; the hollow of one side serves as a channel for the rain, and for that purpose is made of greater radius than the other, which is employed to overlap the edge of the adjoining tile. The tile at the upper end of its under surface has a knob, by which it is hung to the lath. Tiles constitute a very heavy covering, and require the laths by which they are supported to be propóttionately strong. The laths for pan tiles are about three-quarters of an inch thick, and an inch and a quarter broad ; they are generally made of deal. The other sorts of tiles are chiefly plain tiles, hip tiles, and ridge tiles; the latter resemble; half a hollow cylinder, and are laid on the ridges of houses. Ridge tiles are required by statute to be thirteen inches in length, and six inches and a half in breadth.* . - - In Holland, they frequently glaze their roofing tiles, which Increases their durability, but considerably enhances the price of them. The early destruction of unglazed tiles is occasioned by the moisture they imbibe ; for when the water has sunk into them, they break with the action of the frost. Sonini has, however, discovered an excellent preventive of this effect, nearly equal to glazing, and very cheap; he directs us to brush over the tiles with tar, after they have been well warmed in the sun. Tiles, which have been cracked by the frost, may be preserved from the further influence of the same cause, by the like application. - - Of the Tools used in Bricklaying.—The brick trowel, which is used for taking up and spreading the mortar, is also used for cutting the bricks to any required size, and should therefore be made of the best steel, and well tempered. - The hammer used by the bricklayer, is adapted either to strike a blow, or to divide the bricks, as may be required in cutting a hole through a brick wall, or other operations. One end of the head of it has therefore a face similar to that of any common hammer, and the shape of the other end resembles that of a carpenter's axe, though far narrower in proportion to . its length. The handle is inserted much nearer the face of the hammer than the other extremity or edge. Another kind of hammer, often employed in taking down brick-work, differs from the above only in having, instead of the axe part, nearly the shape of an adze, but not so broad for its length; hence it may be driven with facility between bricks to separate them. . The plumb-rule is similar to that used by carpenters and other artisans. It consists of a well-seasoned board, the length of which should at least be four feet; its thickness and breadth are not very material, provided they be sufficient to prevent its warping. Down the middle of one of the broad surfaces of Two or three: the board is drawn a straight line, and at one extremity in this line is attached a small cord with a weight at the lower end. If the long narrow sides of the rule be perfectly straight and parallel with each other, and the line is equidistant from the arris on each side of it, the plummet being hung in this line will form a correct instrument. Either of the long narrow sides of this rule is applied to the wall, so that the plummet and its cord may face the workman, who, by frequently using it, is enabled to carry up his wall perpendicularly. If, in any of these trials, he observes that the cord of the plummet does not coincide with the line on the rule, he sets the bricks fur- ther in or out, as may be required to rectify the error, taking care to do it while the mortar they are set in is yet wet. As the plummet is not made to hang below the rule, a hole is cut in the latter, to allow the cord to hang straight. . - The level employed by the bricklayer, is also similar to that of the carpenter, being of various lengths from six to twelve feet. If one end of the plumb-rule above-mentioned were joined at right angles to the middle of the long marrow edge of another board of the same thickness, but about double its length, it would become a level, the lower edge or side of the piece thus added to the rule, becoming the surface placed on walls, particularly at window sills and wall-plates, to ascertain whether they are horizontal or not. To try the correctness of a level, place it vertically, that is, in the position in which it is used, upon any flat surface, or merely place each end of the bottom edge upon a block of wood, and raise or lower the sup- ports till the cord of the plummet exactly coincides with the line on the perpendicular rule or limb of the instrument. When this is observed, reverse the ends, and if the same coin- cidence then takes place, the level is true ; but if it does not, the bottom must be planed till the trial will succeed. The perpendicular and horizontal parts of the level are not only fastened together by mortise and tenon, but, for greater firm- ness, and to prevent warping, two braces are added, which extend, in a slanting direction, from the horizontal piece nearly to the top of the perpendicular one. • t A large square is employed in setting out the sides of build- ings at right angles; and a small square for trying the bedding of bricks, and squaring the sofits across their breadth, b * is required for drawing the soffit line on the face of TICKS, . The rod, for measuring, is either five or ten feet long; the feet are divided by notches, and one of those next the extre- mity of the rule is divided into inches. Dimensions may be more expeditiously ascertained with the rod than with a pocket rule; but bricklayers are generally provided with a measuring tape, which is coiled up by its winch into a cylin- drical box, of such small dimensions, as to unite a more con- venient portability than the pocket rule, with greater despatch |-in the general operations of measurement, than can be obtained by the use of the rod. - The jointing-rule, employed in running the joints of brick- work, is eight or ten feet long, and four inches broad. When designed for the use of two bricklayers, the latter length is employed. g º - The iron tool used along with the jointing-rule, to mark the joints of brick-work, is called a jointer; its form is nearly that of the letter S, though its flexure is not in proportion so con- siderable. - The raker has its use designated by its name. It is em- ployed to rake or scrape loose and decayed mortar out of the joints of walls, the appearance of which is intended to be im- proved by pointing them afresh. The rake is made of iron, pointed with steel, and at about one-fourth of its length from each extremity it is bent to a right angle, so that it would resemble a Z, if the stroke connecting the top and bottom of that letter were perpendicular instead of slanting. - * Brick-water, or water impregnated with the contents of bricks or tiles, is possessed of properties so remarkable, and at the same time so pernicious in their effects, when used for culinary purposes, that we cannot refuse a place to the following curious experiment made by Dr. Percival, and stated in the first volume of his Essays. He steeped two or three pieces of common brick four days in a basin full of distilled water, which he afterwards decanted off, and examined by various chemical tests. It was not miscible with soap ; struck a lively green with syrup of violets, became slightly lactescent by the volatile alkali, but entirely milky by the fixed alkali, and by a solution of sugar of lead. No change was produced on it by an infusion of tormentil root. Hence the Doctor justly concluded, that the lining of wells with bricks, a practice very common in various places, is extremely improper; as it cannot fail to render the water hard and unwholesome, equally unfit for the use of the kitchen and wash-house. 468 H O Ú PH O Ú dictionARY of MECHANICAL scIENCE. The hod is an angular wooden trough, closed only at one end; so that it resembles the half of a rectangular box divided in such a manner as to consist of two entire sides and one end, armed with a pole or handle about four feet long. . In this utensil, the labourer carries upon his shoulder the bricks and mortar with which he supplies the bricklayer. It is customary to sprinkle the inside of the hod with clean dry sand, before it is filled with mortar, which is thereby prevented from adhering to the wood. - . . . . . A cord or line, to serve as a guide in laying the courses of bricks exactly straight, is stretched close to the wall, and re- moved at the proper intervals as the work advances. This line is fastened to two pointed iron pins, called the line pins, one attached to each end of it. The bricklayer's rammer, resembles the pavier's. If the ground intended for a foundation is deemed not sufficiently solid, it is compressed as much as possible by this tool, a due attention to the use of which will prevent fractures that may endanger the building. - The iron-crow and the pick-axe, are useful assistants to the bricklayer, of obvious utility; being sometimes employed in conjunction, and sometimes alone, in digging, breaking through walls, raising heavy bodies out ef the ground, and similar ope- rations. The compasses for traversing arches, and the granding-stone for sharpening tools, scarcely, perhaps, require to be men- tioned. ,” II. Of Foundations.—Foundations are either natural or arti- ficial : natural, where the ground is rocky or good , artificial, when, from its boggy sandy state, or from its having been lately dug up, piling, or some other precaution, must be resort- ed to, for the support of the building. Appearances are so often deceitful, that the prudent builder will never depend upon them, but will examine the ground intended for ... foundation with the utmost attention. If the ground shake on being struck with the rammer, the nature of it must be ascertained by piercing it with a well-digger's borer. Having found how far the firm ground is beneath the surface, the loose or soft parts must be removed, if not very deep the excavations made on these occasions: should widen upwards, and their sides be cut in the form of steps; by which means a firmer bed will be obtained for the wall than if the sides of the trenches were simply inclined planes. Palladio directs the ground for the foundation to be pene- trated to a sixth part of the whole height of the building, un- less there be cellars, in which case he recommends digging deeper. It is a good rule to make the foundation double the breadth intended for the superincumbent wall, and the con- traction of it should be made alike on both sides. If the earth is very unsolid, piles, close to each other, and | long enough to reach the good ground, must be driven in. The thickness of these piles should not be less than one-twelfth of their length ; they should be made to present as even a surface as possible, and should then be covered with planks. 1t is a curious fact, that dry, straight-grained piles, may e driven much further by the same force, than if they be made of wood in an opposite state. - - } When the infirmity of the ground is uniform, but not very considerable, it may be made good by laying pieces of sound oak about two feet apart, across the breadth of the trench in which the wall is to stand, and when these have been firmly bedded and rammed down, planks of the same timber, or of pitch pine, (which is equally as durable in such situations,) must be laid down and spiked upon them. The planks should be half a foot wider than the base of the foundation wall. Ground of this description may also be made good by ramming large Stones upon it closely together, and extending in breadth about a foot on each side of the wall. Upon the first course of stones, another course, rather narrower, may be laid, taking care, as in walling generally, to make the joints of one course fall on the middle of the stones in the other. - If the ground be found defective in one place and good in another, the unequal settlement which would be the inevitable consequence of building upon it in such a state, may be pre- vented by a plan which is now becoming daily more common, and which, if carefully executed, is always successful. It con- sists in the use of arches, either inverted or suspended, accord. ing to circumstances, which we shall now advert to. When the soft parts of the ground are under the apertures only, inverted arches are to be turned under such apertures. in the manner represented by the annexed figure. By this means the advantage of one continued base is obtained, for % sº - 2% à - 2232 ſ2 2%x, sºmeº Ż % % & º, a º g sº sº - 22 %2% 23222. 22%22 ZºZºZ. '222ſ; . . .222 the piers cannot sink without carrying the arches, and conse-, quently the ground upon which they stand, along with them. The whole building will therefore sink equally, and no fracture of the walls will ensue. So much is the use of inverted arches under apertures approved, that they are considered indispen- sable in all buildings of considerable weight or consequence, even when the ground is not found to be defective. It is suffi- ciently obvious, that the walls of all buildings, the base of the ſoundation of which is not actually laid upon the bare solid rock, will sink a little, and as the pressure of the piers is in- comparably greater than that of the low piece of walling under the apertures the risk is extreme, that the resistance of the ground against this low walling will not allow it to sink with the piers, and consequently the fracture of the wall, and pro- bably the breaking of the window sills, will be the consequence. The inverted arches prevent these bad effects; and as they have so important a service to perform, they should be thrown with the greatest care, closely jointed, and their depth at least equal to half their width. j When the reverse of the preceding case occurs, that is, when the solid parts of a foundation are only to be found under apertures, then piers must be built in these places, and arches suspended between them, as represented in the following figure. Ž% gº % % {2}. º 2% % & Kºº *2 2. & 2222222 It is best to make the middle of the pier rest upon the mid- dle of the summit of the arch. If the pier does not cover the arch, the narrower it is, the greater should be the curvature of the latter at the apex. When arches are used in this way, the intrados ought to be clear, that they may have their full effect. The uniform resistance of the ground upon which the piers are erected, is also of greater importance than even its perfect hardness; for if it resists uniformly, the building will sink in every part alike, and remain uninjured. . When wood is laid in the trench of a foundation, the first course of stone or brick should be laid as close as possible, without mortar, which injures the timber. If there be any dif- ference in the quality of the bricks, the strongest and closest, which are leas; liable to imbibe moisture, should be selected for foundation work. §. t III. Of Cements, Lime, &c.—The bricklayer being provided with tools, with bricks, and having prepared the trenches of his foundation for walling, finds himself in immediate want of mortar or cement, a subject which next claims our consi- deration. The nature and best methods of preparing calcareous cements have been investigated by Dr. Higgins with great ability and success. He has advanced the most satisfactory proofs, founded upon analysis, that the Romans, whose mortar on cement, after a lapse of two thousand years, instead of being decayed, has become as hard as the stones it binds together, possessed no uncommon secret, which we are unable to discover. His publication first appeared in 1780, and is evidently the production of a liberal and intelligent mind. He struck into a path with which we were but little acquainted, though the knowledge of it is of very considerable impor- tance to the public collectively, as well as to individuals; for it is certainly lamentable to observe public ro private edi- H. O. U H. O. U DICTIONARY OF MECHANICAL SCIENCE. 469 J. fices, insecure, or prematurely mouldering away, from the ignorance or disregard of a few particulars, which might not only be observed with ease, but, in many instances, with a diminution of the original expense. The Doctor’s conclusions, which were drawn from innumerable experiments, constitute a great portion of the best part of our knowledge on this sub- ject at the present time; but though so many years have elapsed since they were communicated to the 'public, they are far from being yet generally known, and consequently are not reduced into general practice. " * - Such is the neglect shewn on this subject, that the timbers of our houses last longer than the walls, unless the mouldering cement be frequently replaced by pointing. The following | directions, for preparing durable mortar or stucco, contain the result of the Doctor's experience, and have been attended to with remarkable success. Sharp sand free from clay, salts, calcareous, gypseous, or other grains less hard and durable than quartz, is better than any other. When a coarse and a fine sand, corresponding in the size of their grains to the coarse and fine sand hereafter described, cannot be easily obtained native, the following method of sorting and cleansing it must be resorted to. Let the sand be sifted in streaming clear water, through a sieve which will allow all grains not exceeding one-sixteenth of an inch to pass through, and let the stream of water be regulated so as to wash away the very fine parts of the sand, the clay, and every other matter lighter than sand. The coarse rubbish left on the sieve must be rejected. The sand which subsides in the receptacle must then be further cleansed and sorted into two parcels, by the use of a sieve which allows no grains to pass but what are less than one-thirteenth of an inch in dia- meter. That part which passes through this sieve, we shall call fine sand, the remaining portion, coarse sand. These separate portions may then be dried in the sun, or by means of a fire. - - - That sort of lime must be chosen which heats the most in slaking, and slakes the quickest when duly watered; which is the freshest made, and has been the closest kept, which dis- solves in distilled vinegar with the least effervescence, and leaves the smallest residue insoluble, and in this residue the Smallest quantity of clay, gypsum, or martial matter. Put fourteen pounds of the lime chosen according to these im- portant rules, into a brass wire sieve still finer than the last mentioned. , Slake the lime by alternately plunging it into and raising it out of a butt of soft water; reject all the matter which does not easily pass through the sieve, and use fresh portions of Hime in a similar manner, until as many ounces of lime have passed through the sieve as there are quarts of water in the butt. This is the lime-water, which contributes mate- rially to the excellence of the stucco. As soon as a sufficient portion of lime has been imparted to it, it should be closely covered until it becomes clear, and then be drawn off, by wooden cocks, placed at different heights as the lime sub- sides, without breaking the crust formed on the surface. The freer the water is from saline matter, the better will this liquor be. Lime-water must be kept in air-tight vessels till the moment it is used. t Slake fifty-six pounds of lime chosen as above directed, by gradually sprinkling on it the lime water. Sift the slaked part of the lime immediately through the last mentioned fine brass- wire sieve ; the lime which passes must be used instantly, or kept in air-tight vessels, and the rest rejected. This finer, richer part of the lime may be called purified lime. It is always advisable to sift the lime immediately after the slaking, other- wise much of the ill-burnt lime and heterogeneous matter which it may contain, will pass through the sieve. The materials of the cement being thus prepared, take fifty- | six pounds of the coarse sand, and forty-two pounds of the fine Sand ; mix them on a large plank of hard wood placed horizon- tally ; then spread the sand so that it may stand to the height of six inches with a flat surface on the plank, and wet it with jime- water, of which so much must be allowed to flow away off the plank, as the sand in the condition described cannot retain. To the wetted sand add fourteen pounds of the purified lime in several successive portions, mixing and beating them up toge- ther with the instruments generally used in making fine mortar. Then add fourteen pounds of bone-ashes in successive por- tions, mixing and beating all together. The quicker and more perfectly these materials are mixed and beaten together, and the sooner the cement thus formed is used, the better it will be. As this cement is shorter than water or common stucco, and dries sooner, it ought to be worked expeditiously in all cases, and in stuccoing it ought to be laid on by sliding the trowel upwards on it. The materials used along with it in building, or the ground on which it is laid in stuccoing, ought to be well wetted with the lime-water at the instant of laying it on ; and when the cement requires moistening, lime-water should always be used. The proportions above given are intended for a cemfºnt made with sharp sand, for incrustation in exposed situations, where it is necessary to guard against the effects of hot weather and rain. In general, half this quantity of bone-ashes will be found sufficient; and although the incrustation in this latter case will not harden deeply so soon, it will be ultimately stronger, pro- vided the weather be favourable. - When a mortar or cement of a fine texture is required, take ninety-eight pounds of the fine sand: wet it with the lime- water, and mix it with the purified lime and the bone-ashes in the quantities and in the manner above described, with this difference only, that fifteen pounds or thereabouts of lime are to be used instead of fourteen pounds, if the greater part of the sand be very fine. This cement is suitable for the last coating of any work intended to imitate the finer grained stones; but it may be applied to all the uses of the first men- tioned composition. - When a mortar or cement is required, which shall be still cheaper and more coarsely grained, much coarser sand than the coarsest sort already spoken of may be made use of; for the coarser the sand, the less the proportion of lime which will be required. For example, of the coarsest sand alluded to, take fifty-six pounds; of the coarse sand which passes through the meshes of a sieve one-sixteenth of an inch in diameter, twenty-eight pounds; and of the fine sand, fourteen pounds; and after mixing these, and wetting them with lime-water, in the manner already described, add fourteen pounds, or some- what less, of the purified lime, and then fourteen pounds or somewhat less of the bone-ash. When these cements are intended to be white, white sand, white lime, and the whitest bone-ash, are to be chosen. Gray sand, and gray bone-ash, formed of half-burnt bones, are to be chosen to make the cement gray ; and any other colour may be obtained either by choosing coloured sand, or by the admix- ture of the necessary quantity of coloured talc in powder, or of coloured vitreous or metallic powders, or other ingredients of a similar nature. These cements are applicable in forming artificial stone, by making alternate layers of the cement and of flint, hard stone, or brick, in moulds of the figure of the intended stone ; the stones thus formed being exposed to the open air to harden, but not exposed to rain till they are almost as strong as fresh Portland stone. They may be made very hard, and beautiful, by soaking them, after they are thoroughly dry, in the Jime- water, and repeating this process several times at distant inter- vals. Incrustations, also, are greatly benefited by the appli- cation of lime-water, the entrance of which is facilitated by the use of bone-ashes in the cement. • When any of the above cements are intended to be used for water-fences, two-thirds of the prescribed quantity of bone- ashes are to be omitted, and an equal measure of powdered terras used instead; and if the sand employed be not of the coarsest sort, more terras must be added, so that the terras shall be by weight one-sixth part of the weight of the sand. . When a cement is required of the finest grain, or in a fluid form, so that it may be applied with a brush, for the purpose of smoothing and finishing the stronger crustaceous works, or for washing walls to a lively and uniform colour, the fine pow- der of calcined ſlints, or the powder of any quartzose or hard earthy substance, may be used in the place of sand; but in a quantity smaller as the flint or other powder is finer; so that the powder shall not be more than six times the weight of the lime, nor less than four times its weight. The greater the quantity of lime within these limits, the more the cement will º 6 D 470 *H O Ú \ . H. Q U. DICTIONARY OF MECHANICAL SCIENCE. be apt to crack by quick, drying, and vica versa. For washing walls, the cement should not be made thicker than new cream, and should be laid on briskly with a brush, in dry weather. Fine yellow ochre is the cheapest colouring ingredient, for such a wash, when it is required to imitate. Bath stone, or ; the warmer white stones. 4 . . . . Where sand cannot be procured, any durable stony body, or baked earth grossly powdered, and sorted as if it were sand, may be used, measure for measure, but not weight for weight, unless the same bulk of the gross powder be the same as that of sand. But all substitutes for pure siliceous sand, are im- perfect in proportion as the particles of which they are composed, are less hard than those of that material. The scrapings of roads, which consist principally of powdered cal- careous stone, the old mortar and other rubbish from ancient buildings, have often been more strongly recommended than they deserve. These, and all muddy, soft, and minutely divided. matters; require a large proportion of lime, and never possess the hardness and durability which belong to good mortar. Sea sand, well washed in fresh water, is as good as any other round sand; but if used without being freed from salt, the mortar made with it is extremely liable to be damp. The proportion of lime may be increased without inconve- nience, when the cement or stucco is to be applied where it is not liable to dry quickly; and in the contrary circumstance, this proportion may be diminished. The defect of lime in quantity or quality, is best supplied by 'soaking the work, at distant intervals of time, with lime-water. It is proper to mix hair with these cements, when employed for interior work. The power of almost every well dried or burnt animal sub- stance may be used instead of bone-ash. . The bone-ashes facilitate the operation of plastering, by increasing the plasticity of the mortar into which they enter. They also render the mortar less liable to crack, and cause it to acquire more quickly that state in which it is not easily in- jured by unexpected rain. If employed in a less proportion than one-fourth of the lime, they are of little use, and if they exceed the lime in quantity they are injurious to the cement. Hence the use of them should be regulated according to the following circumstances: when the artist is more solicitous to Secure an incrustation from the effect of hot weather, to finish it quickly, and to guard against rain, than to make it durable in the highest degree, he may use as much bone-ashes as lime; but when the season, exposure, and other circumstances, per- mit him to attend solely to the true excellence and duration of his work, he must use, in his best calcareous cements, only one part of bone-ashes for every four parts of lime. By these rules he may choose intermediate quantities adapted to his pur- poses. The bone-ashes should not be in so coarse a powder as they are when used for cupels, yet they should by no means be levigated or ground to extreme fineness. - By sharp sand, is meant such sand as consists of grains with flat surfaces; these flat surfaces, when enveloped and cemented together by the lime paste, possess a much stronger cohesion than if the grains were globular. The preceding method of making mortar or stucco differs, it will be perceived, from the common process in several essen- tial particulars; among which, the purity and sorting of the sand, the use of lime-water, the newness of the lime, and the large proportion of the sand to the lime, ought to be particu- Jarly noticed. . It may be useful to inquire into some of the causes of differences of practice so remarkable. When the sand contains much clay, or other impurities, the bricklayers find that the best mortar they can make, must con- tain about one-half lime; and in consequence pronounce, with- out further investigation, half sand, and half lime to be the best composition. But with sand requiring so much lime, they never can make durable mortar, though of this fact it may be difficult to convince those who are little disposed to investigate causes. Too many artisans entertain an opinion that they have nothing new to learn which is worth notice; they are apt in effect to say, that having served an apprenticeship to their business they ought to know something; and thus, because they ought to himow something, they seem to expect submission to their very errors. To such characters we speak not; to con- vince them is impossible, and therefore the attempt is foily, But those who consider, the interest of their employers, and that the warmth; dryness, and salubrity of a house, so far as the building is concerned, is completely in their power, will ; not despise any hint which may extend their resources. It is a common fault to build lime-kilns so high, that, at the bottom of the cavity, the lime is ready perhaps eighteen hours before that in the upper part, and is greatly injured by its ex- posure to the draft of air passing through the fire. Lime-kilns ought to be made much broader and shallower than customary, by a quick current of air. most eminent degree the properties of lime, when they are with the cavity tapering upwards, and should terminate in a lofty flue, in order to accelerate the combustion, when required, Calcareous stones acquire in the slowly heated in small fragments of uniform size, until they appear to glow with a white heat, and this is continued until they become non-effervescent if steeped in an acid. The art of preparing lime consists chiefly in attending to these parti- culars. The whiteness of lime shews it to be free from metallic impregnation. Merely to keep lime dry is not enough to pre- serve it; it grows worse for mortar every day it is kept in heaps or untight casks, and is soon reduced nearly to the state of chalk. It may be greatly debased, without slaking sensibly, posure to the air are unfit for mortar. | water, and yet remain perfectly dry. and such parts or fragments as fall to powder merely by ex- It has been found by experiment, that lime will absorb one-fourth of its weight o. Bishop Watson found, that, upon an average, every ton of limestone produced eleven hundred weight, one quarter, and four pounds, of lime, weighed before it was cold; and that, when exposed to the air, it in- creased in weight daily, at the rate of a hundred weight per ton, for the first five or six days after it was drawn from the kiln. Hence those who have to fetch lime from great dis- tances, may save even in point of cartage, by receiving it as it is taken out of the kiln. wards, whatever its faults, in other respects, may be. position, the less the cracks will be seen. Mortar which sets without cracking, whether this be owing: to the due proportion of sand, or to the slow exhalation of the water from mortar containing less sand, never cracks after- As it is the lime paste, and not the sand, which contracts and pro- duces fissures in drying, so the more sand there is in the com- Mortar which is liable to crack, becomes irreparably injured by frequent alter- nations of wetting and freezing ; for the water imbibed by the smallest fissures, dilating as it congeals, loosens its whole tex- ture. Where it is composed of seven parts of sorted sand to one of lime, it is not disposed to crack. That mortar may become indurated the soonest and in the highest degree, and operate the most effectually as a cement, it must be suffered to dry gently and set; the exsiccation of it must be effected by temperate air, and not accelerated by the heat of the sun or fire. It must not be wetted till after it sets; and afterwards it ought to be protected from wet as much as possible, until it is completely indurated; the absorp- tion of carbonic acid must be prevented as much as possible till the mortar is finally placed and quiescent, and then it must be as freely exposed to the open air as the work will admit, in order to supply carbonic acid, and enable it sooner to sustain the trials to swhich mortar is exposed in cementitious buildings and incrustations. To shew more clearly how much our slight buildings are weakened by the agitations and percus- sions to which they are exposed, first in erecting the walls and settling the timbers, and then in driving those wedges to which the wainscots, mantle-pieces, and other ornaments, are fastened, we must observe, that the absorption of carbonic acid by mortar contributes nothing to the strength of it, if it enter before it is finally fixed in a quiescent state. A little experience is sufficient to teach us, that the same matter which assists in the induration of mortar, never serves to repair the fissures, or solution of continuity between the bricks and ce- ment, which happens after it is set. When mortar is set, and before it is indurated, it may be easily severed from the bricks and crumbled; and for want of softness, it cannot bend into the fissures, or resume its former condition in any time. Hence by heavy blows, and in wedging, our walls must be greatly weakened; and the more so, as the houses are slight, quickly built, and hastily ſinished. H O Ú. H. G. J. 47 DICTIONARY OF MECHANICAL SCIENCE. * Nothing is more common than for bricklayers to keep their mortar some time exposed to the air in heaps, before they con- sider it proper for use; a practice which may perhaps be ac- counted for, if we consider that some portions of every kind of lime used in this country, do not slake freely, by reason of their not being sufficiently burned, or of the admixture of gyp- seous or argillaceous matter; which portions, like marl, slake in time, though not so quickly as the purer lime. The plas- terers, who use a finer kind of mortar, made of sand and lime, observe that their stucco blisters, if it contain small bits of unsiaked lime, and as smoothness of surface is with them of more. consequence than excessive hardness, they take care to secure the perfect slaking of their lime by allowing sufficient time for the imperfect parts to be penetrated by the moisture. The bricklayers, trusting, perhaps, more to the judgment of the plasterers, in this respect, than to their own, and considering it very convenient to slake a large quantity of lime at once, follow the same practice, without caring for or apprehending the real fact, that mortar. is worse for every hour it is kept, and that they are taking such measures as will prevent it from ever acquiring that degree of hardness in which its perfection consists. - - : Among the circumstances which contribute to the speedy ruin of modern buildings, it may also be observed, that mortar made with bad lime, and a great excess of it, is used with dry bricks, and not unfrequently with warm ones. These imme- diately imbibe or dissipate much of the water, and as the cement approaches nearer to be dry, whilst it is still liable to be displaced by the percussions of the workmen, render it little better than equivalent to a mixture of sand and pow- dered chalk. To make strong work, the bricks ought to be soaked; in lime-water, and freed from the dust with which they are commonly covered. By this means the bricks are rendered closer and harder, the cement, by setting slowly, admits the motion which the bricks receive when the workman dresses them, without being impaired, and it adheres and ind ates more perfectly. This steeping of the bricks is an imitation of the practice of the plasterers, who always wet the wall before they commence their work, because they know the cement will not otherwise adhere. This ought to be done as long as the wall is thirsty, and lime-water is the most proper l, quid they can use. The same advantage that attends the soaking of bricks, would attend the soaking of bibulous stones in lime-water. Mortar made with sand containing one-seventh or one-eighth of fat clay, moulders in winter like marl ; a circumstance which proves the propriety of freeing from clay the sand used in mor- tar. The washing performed for this purpose, will be found a very cheap operation, even in cities, if the water which carries off the clay be directed into a receptacle where it may be depurated by subsidence for repeated use. Chalk lime may be easily prepared, so as to be fully equal if not superior to stone lime. The reason why this is not generally thought to be the case, probably is, that not being of so close a texture, it is sooner spoiled by the absorption of carbonic acid, when exposed to the atmosphere after it is made. A cask of chalk lime should therefore never be opened till the moment it is to be slaked, and the greatest expedition should be used in the slaking, and in the making and applying the mortar to use. In the quiescent air of a room, a pound avoirdupois of chalk lime becomes two ounces and a half heavier in two days; and nearly the whole of this increase of weight consists of the car- bonic acid which it has imbibed from the atmºsphere. The fittest water for making mortar, is rain water; river water holds the next place; land water the next; spring water the last; sea water, and all waters noticed medicinally or otherwise, for their saline contents, ought never to be used for this purpose. - t The compositions mostly used for stuccoing within doors, are incapable of hardening considerably, and when they are laid on the naked walls, soon become tarnished, unsightly, and . inconvenient, by the damps which workmen call sweating. Sometimes these damps are occasioned by the bad construc- tion of the walls, the joints of the facing bricks having become hollow by the decay of the mortar, or when the copings or gut- ters are defective: a damp by transpiration also occurs when j } the principal walls are stuccoed before they are dried, or when the materials of them are so spongy as to imbibe the rain, and : the circulation of air is not sufficient to waft away the transud- ing moisture. The damp' by condensation is also very com- mon, and appears most on the closest incrustations, however perfect and old the walls may be. In such instances, the damp is owing to the closeness of the body, and a stucco per- vious in a certain degree to air and moisture, will be free from it, as well as from the damp before mentioned. The customary mode of avoiding these damps; is to case the principal walls of houses with lathwork, on which the incrustation or plaster is laid at some distance fromiithe wall. The narrowing of rooms and passages very perceptibly is the consequence of this method, besides its expense. Bone-ashes, each grain of which is tubulated is every direction; added to the stucco in half the quantity of the lime, are a preventive of these damps without lath work. * . The drying, induration, and texture of incrustations made on brick walls and other irregular surfaces, are always so far unequal as to exhibit visible traces which deform the work, and cannot be effectually obliterated by any known method so convenient as that of covering the first coarse incrustation, after it has dried, with another coat which may be made finer and smoother. Thus the expense of fine-grained, smooth, or coloured stucco, is rendered moderate; because the finer, or the colouring ingredients, may be reserved for the exterior coat, which will last for ages, if the cement be good. To tinge a cement sufficiently, of any colour which is not found in sand, so that the incrustation shall not be impaired, and that the colour shall be as durable as the cement, the most proper ingredients which can be used in lieu of sand; or of part of it, are coloured glasses or coloured stones of the hard- est kind, beaten to coarse powder; the finer parts of which are to be washed away, not merely because they are injurious to the cement, but because they contribute very little to the intended colour. e Stucco made with the best proportions of lime, sand, and lime-water, is not bettered by painting as soon as it dries; as this covering retards the induration of it, by cutting off its communication with the air. It therefore renders it liable to be irreparably injured in wet weather, wherever the water can get behind the paint. If paint or oil-ought ever to be applied on such stucco, it ought not to be laid on in less than a year after the incrustation is made. The painting and sanding of the common defective incrustations, contribute very little to their duration, although it hardens them at the surface; for it does not effectually prevent them from cracking, and it avails very little to paint the cracked stucco again, because cracked stucco is always hollow, as the workmen term it; that is, it parts from the wall in the parts contiguous to the cracks, sounds hollow on being struck with the knuckle, and falls off in a few years, if it be so thick and large in extent as to break the adhering portions by its weight. - Mortar made of sand; water, and lime; whatever may be the proportions of the mixture, cannot be employed in aqueducts, reservoirs, and other aquatic buildings, unless sufficient time be allowed for its perfect induration before the admission of the water; but when mixed up with a quantity of terras, as already stated, it acquires the desirable property of hardening under water. A few additional remarks on this subject will perhaps be acceptable. A mortar made of terras powder and jime was used in water-fences by the Romans, and has been generally employed in such structures, ever since their time. As it sets quickly, and when set is impenetrable to water, some people have hastily concluded that it is the best kind of mortar for any purpose. But it is found by experience, that mortar made of terras powder, whether coarse or fine, will not grow so hard as mortar made with lime and sand, nor endure the weather so well; on the contrary, it is apt to crack and perish in the open air. Its efficacy in water-fences is ex- perieneed only where it is always kept wet, and seems to de- pend principally upon the property which the powder of terras has, in common with other argillaceous bodies, but in a higher degree, of expediting the crystallization of the calcareous matter, by imbibing the water in which it is diffused in the mortar, and of swelling during this absorption, so much as 472 H O Ú. H O U DICTIONARY OF MECHANICAL scIENCE. to render the mortar impenetrable to any moré water. It seems, also, that an acid of the vitriolic kind, which is contain- ed in terras, contributes to the speedy setting of the cement, by reducing a part of the lime to the condition of gypsum. Terras is a volcanic production, consisting chiefly of clay and oxide of iron indurated together; and baked clay, reduced to powder, communicates to mortar properties of a similar kind. -- - - - Pozzolana is another volcanic production differing little from terras, as to the effect it produces in mortar. It is thrown out of volcanoes in the form of ashes, and is found in many countries, but most abundantly in the kingdom of Naples. The cement used by Smeaton, in the construction of the Eddystone light-house, was composed of equal parts by measure of lime and pozzolana; a mixture which was deemed the most suitable, as the building was exposed to the utmost violence of the sea; but a composition exceedingly proper for aquatic works in general; may be composed of two parts of lime, one of pozzolana, and three of clean sand. - - . It has lately been discovered, that manganese is a valuable ingredient in water-cements, if used in the following manner; mix together four parts of gray clay, six of the black oxide of manganese, and ninety of good limestone reduced to fine pow- der; then calcine the whole to expel the carbonic acid. When this mixture has been well calcined and cooled, it is to be worked into the consistence of a soft paste with sixty parts of washed sand. If a lump of this cement be thrown into water, it will harden immediately. IV. Of Brick Bond and Walling.—When a brick is laid so that its length is in the direction of the length of the wall, it is called a stretcher; and when its length crosses that of the wall, it is called a keader. & - The term bond is applied to any disposition of the bricks, by which the continuity, in a straight line, of the joints of a wall is interrupted. It is obvious that a bond may be adopted, which will interrupt the rectilinear direction of both the hori- zontal and vertical joints of a wall; but in the two kinds of bond which have hitherto prevailed, the horizontal joints are continued in the same line round the whole building, and the vertical ones only interrupted. When the wall is only intended to be half a brick, or four inches and a half in thickness, the whole of the bricks are laid so as to form stretchers, that is, their length is laid in the direction of the length of the wall, and the bond is obtained simply by making the vertical joints in every course exactly opposite the middle of the bricks above and below. But when the wall is intended to be the length of a brick or more in thickness, it would be apt to split into parts if it consisted only of two or more walls separately bonded, as in the instance just mentioned of the half brick wall. The bricks, therefore, in thick walls, must be connected in their breadth as well as their length, and this is done according to two principal modes, one of which is called English, the other Flemish bond. English bond consists of headers and stretchers crossing each other in separate horizontal courses. In Flemish bond, the headers and stretchers are placed alternately in the same horizontal course. Flemish bond is now so common, that hardly any other kind is to be seen; it is preferred, for its ap- pearance, to the English, which is much superior in point of strength, and in facility of execution. Many attempts have been made to unite Flemish facings with complete bond, but without success. Some have laid thin slips of iron occasion- ally in the horizontal joints between the two courses; and others have laid diagonal courses of bricks in the core of thick walls, so as to cross each other at right angles in successive courses. By the latter means, though the bricks in the middle of the core have a strong bond, yet as they form triangular interstices with the bricks on each side, the bond of the whole wall is very incomplete. As the adjustment of the bricks in one course must depend on the course beneath, the latter, in making the Flemish bond, must be seen or recollected by the workman. The view of the joints of the under course is hin- dered by the mortar with which they are covered, to bed the bricks of the succeeding course upon, and it is perplexing for the workman to recollect the arrangement of them, so that he is in danger of making the joints frequently to correspond, \-- and thus rendering the bond imperfect. In the old English bond, the outside of each course points out the proper dis- position of the next, so that it is an easy matter for the work- man to avoid error. The following plans of walls in English bond, which well deserve to be revived in this country, will render this subject more intelligible : The annexed figure represents the bond of a nine-inch wall. In order that two vertical joints may not run over each other, at the end of the first stretcher from the corner, after placing the return corner stretcher, which becomes a header in the face that the stretcher is in below, half the length of which it covers, a half brick is placed on its tº side, so that with the return' corner stretcher, it extends six inches and three-quarters, and thus a lap of two inches and a quarter is obtained for the next header ; and the bond is continued by working up the wall with alter. nate rows of headers and stretchers mutually crossing each other. The half brick, or brickbat, thus introduced, is called a closer, and must be divided, it will be understood, through its two broadest surfaces, in the direction of their length. The same effect might be obtained by the introduction of a three- quarter brick at the corner of the stretching course, for then when the corner header is laid over it, a lap of two inches and a quarter will be left at the end of the stretchers below for the next header, the middle of which, when laid, will be over the joint below the stretcher, and thus constitute a bond as before. The brick for the three-quarter bat, or closer, must be divided through its two broadest surfaces, in the direction of their breadth. - The English bond of a brick and a half, or fourteen-inch wall, ap- pears in this figure. Here the stretching course is so disposed, that the middle of the breadth of the bricks in the same layer or level, falls alternately upon the middle of the stretchers, and upon the joints between the stretchers. É * 22 % % * The English bond of a two-brick wall, fig. 1. To break the joints in the core of the wall, every alternate header, in the ; heading course, is only half a brick thick. The English bond Fig. 1. Fig. 2. Z. Pº * * * * * * *** * of a wall two bricks and a half in thickness, fig. 2. The dispo- sition of the bricks is similar to that of those in fig. 1. Part of the front of a wall in English bond, fig. 3, the un- broken side being the corner. The Flemish bond of a nine- inch wall, fig. 4. ... Two stretchers lie between two headers; and bricks being twice as long as they are broad, the breadth Fig. 3. Fig. 4. Z. £Z gº g &ZZZZZZZ à% - ZZ ZZ ZZZZZ º ZZ 22 %. ŻZYZZ - % º of the two stretchers is equal to the length of the header, which is the whole thickness of the wall. The dotted lines shew the disposition of the bricks in the second course, . - H O Ú H O Ú DICTIONARY of MECHANICAL SciFNCE. 473 The Flemish bond of a brick and a half or fourteen-inch wall, fig. 5. On one side the bricks are laid as in fig. 4, and on the other side, half headers are placed opposite the middle of the stretchers, and the middle of the stretchers opposite the middle of the end of the headers. Fig. 6, another example of Fig. 5. %% . º % % % 2 % º % Flemish bond, for a wall of the same thickness as the last. Here the disposition of the bricks is alike on both sides of the wall, the tail of the headers being placed contiguous to each other, an arrangement that produces, in the core of the wall, square spaces, which must be filled with half bricks. Fig. 7, part of the front of a wall in Fig. 7. % %% º Ż 2322 % Žiž % & Ø º ſº g Ż Flemish bond, reaching on one side % ſº to the corner. . . . Fig. 1, 2, 3, and 4, in the following engraving, exhibit plans of brick piers in Flemish bond. No. 1, in each figure, shews the bottom course, and No. 2 the upper course; or, which amounts to the same thing, No. 2 may be considered the lower course, and No. 1 will then be the upper one. 2 % % à T % Ž im º 2 % º %% ºn tº Fig. 1, is a pier, two bricks, that is, eighteen inches, square; for in speaking of the thickness of a wall or pier as consisting of so many bricks, the length of a brick is always to be under- stood. Fig. 2, a two and a half brick pier. Fig. 3, a pier three bricks square. Fig. 4, a pier three bricks and a half square. Before we take leave of the subject of bond, we must remark, that a patent has within a few years been taken out, by Moore and Co. of London, for a vertical bond, which is intended to supersede the use of the bond timbers introduced to secure the equal settlement of the wall. In case of fire, when the bond timbers of a house are consumed, the falling of the wall almost necessarily follows. The patentees, therefore, instead of these timbers, place rows of hard strong bricks perpendicu- larly in the middle of their walls, at short distances from each other in height as well as horizontal measurement, and they place each row of the perpendicular bricks in such a manner, as to be opposite the middle of the space between the row standing in the same position immediately above or below it. This plan for obtaining a vertical bond seems new and inge- nious, and is applicable, as indeed the patentees observe, to stone walls, as well as to those of brick. f The following figure represents a straight arch, which is usually made the height of four eourses of brick; but in con- siderable buildings, it may with great propriety be made the height of five courses. The manner of drawing the joints of a straight arch will be evident from an inspection of the figure. The joints of the arch-stones must all be made to lie in a direct one to the point C. The point C is easily obtained, as it is as far from the points A and B,) which are separated by the whole breadth of the aperture,) as A and B are from each other. Hence the lines connecting A, B, and C, form an equilateral triangle. To key the arch in, it is usual to have a brick, and not the joint between two bricks, in the centre; and therefore the division of the arch must be managed accordingly. Though the brick in the middle tapers more in the same length than the extreme bricks, yet as the difference is very small, it is disregarded, from the great convenience of drawing all the bricks with the same mould. It may, however, be observed, that the real taper of the mould may be a medium between that required for the middle and that for either ex- treme distance. But whether this be done or not, the defect will not appear in practice. Fig. 1, a scheme arch, one brick, that is, nine inches high. Fig. 2, a semicircular arch, one brick high. Fig. 1. % #. É The subjoined figure is an elliptical arch, one brick high, the top of which is divided into equal parts, and not the under side. It is struck from three centres, A, B, and C. . The arches delineated in the last three figures are often made a brick and a half, or even two bricks high; but for crowning the apertures of ordinary dwellings, the height of one brick is deemed sufficient, both for stability and appearance. In arches of one brick high, when the walls are only half a brick thick, it is evident there is no necessity d for joints following the course of the arch in every alternate brick. Accordingly, these joints, in such walls, are generally false ones, being merely nicks of little depth cut with the tin-saw ; and are made as a kind o- decoration, in arches exposed to view, to give, when pointed along with the other joints, a more lively appearance. But when the walls are of one brick or a greater thickness, the joints in question must be real, and formed of two bricks disposed as headers, for the sake of bond. ; : ; : de This figure is a plan of Tap per’s improved method of groin- ing. The improvement consists -- in raising the angles from an octagonal pier instead of a ge **. & gº tº * g .* 2° S., ". tº e º «» «º & • ſº tº e * * * t ; : º, square one. By this means, ; : 3 the angles of the groins are ; : ...'..." strengthened by carrying the ......... band round the diagonals of º zºº-------- equal breadth, thus affording “. … : :º, better bond to the bricks, which ... : : º, are usually so much cut away, * * = e * that instead of giving support, they are themselves supported by the adjacent filling-in arches. Square piers are very inconvenient in cellars, by hindering the turning of goods round their angles. - In different parts of the country, it will naturally be sup- 6 E '474 H O U 'H o U dICTIONARY OF MEGHANICAL SCIENCE., posed that many differences of practice will prevail in the details of building. Several of these differences originatein local peculiarities of materials, of one kind or another; but there is one, not belonging to this class, respecting which we might have expected to find a very general uniformity of practice. In London, and a wide district around, the scaffolding for the workmen, in erecting the walls of a building, is external; but in Liverpool, and several other parts of Lancashire, and adja- cent: counties, the scaffolding is wholly within the building, whatever may be its size or consequence. On the merits of either plan we shall not offer a decisive opinion; yet we may || remark, that external scaffolding is not only the most expensive, but has an air of insecurity to the workman, and of incompact- 'ness, which is unpleasant to the observer, especially when he is aware that such cumbersome appurtenances may be dispensed with. In populous towns, or confined places, also, the en- croachment of external scaffolding upon the street, is not a trifling inconvenience, particularly as the bricks and other ma- terials must be at some distance beyond its limits, to prevent accidents. Interior scaffolding, on the contrary, being sup- ported on the joists of each floor as the work proceeds, is erected with little trouble or expense, the workman marks his joints with as much ease and regularity as if he were at the outside, such a thing as a falling brick or splinter is hardly known, and the bricks and other materials may, if necessary, be laid close to the wall, so as to occasion little inconvenience in the street. - To obtain the desirable requisite of dry walls, we have already observed, that the usual resort is the use of interior lathwork, and have adverted to the means of preventing this expense, by a proper composition of the mortar or stucco. Another expedient in common use, intended to secure the dryness of the walls when lathwork is deemed too expensive, consists in leaving a portion of the bricks in the core or middle of the walls, without mortar from the top to the bottom. The interstices thus left, serve, in some measure, the same purpose as the space between the lathwork and the bricks. Perhaps the reference to a figure may make the nature of the plan more easily apprehended. In the nine-inch wall, in the elliptical arch, the longitudinal joint a b, and the middle third, or from e to f, of the transverse joint c d, would be left without mortar; and the same thing is done to all the other joints or portions of joints similarly situated. By this contrivance, the bond of the wall is greatly weakened; but strength, it will be perceived, is not the object of it; the walls in the inside are drier, they look as well, the house will let for as high a rent as a stronger, and its instability is left for the purchaser, or the next generation, to discover. It has not unfrequently happened, however, that the slightness of modern houses has been quickly proved, by their having tumbled down before they were even finished. There is one advantage of casing external walls with lathwork, which is independent of damp, and therefore not the object, though the consequence, of that operation. As air is one of the most imperfect conductors of heat known, the column of it included between the plaster or stucco and the bricks, tends to prevent the temperature of apartments from being affected by sudden vicissitudes in the heat of the external atmosphere. Lathwork casing should be composed of well-seasoned heart laths, as the sap laths will shrink. Reeds are used instead of laths in some parts of the country: but they require a greater quantity of mortar than laths, and produce on the whole little or no saving. Frost is exceedingly prejudicial to new brick-work, and its effects ought to be guarded against with the utmost care. When it is apprehended, the wall should not be left uncovered at night; a capping of straw or of weather-boarding formed like the roof of a house, to carry off the rain equally on both sides, if any occur, is generally employed; and sometimes for the more complete security, both the straw and the boarding are employed at the same time, the straw being placed next the wall. In winter, the mortar should be used stiffer than at other seasons, and if a quantity of lime, which is quite fresh, or has been kept in tight casks till it is wanted, were reduced to powder without slaking, and well beat up with it, the set- ting of it would be very materially hastened. Where strong work is required, it is not expedient, even in winter, to relin- quish the practice already recommended, of steeping the bricks in lime-water; and when this is done, the method just mentioned of preparing the mortar is the more useful. The bricks should not, however, be laid so dripping wet in winter as in warm dry weather. When the practice of steeping the bricks in lime-water is rejected as too troublesome, the sprin- kling of each course with common water may be considered the easiest substitute for that operation. This method of strength- ening the work was adopted in the building of the College of Physicians, London, at the judicious suggestion of Dr. Hooke. If the mortar has been suffered to lie any time, previous to its being used, the labourer should beat it up again to give it tenacity, and to prevent the bricklayer from losing time in working it with his trowel. - In working up the wall, it is by no means advisable to work more than four or five feet in height at a time; for as all walls shrink a little soon after building, if the different parts of the circuit of the walls or carcass be carried up at distant inter- vals, one part will sink by itself, and will consequently sepa- rate from the other part which has become fixed. No portion of a wall ought to be carried up more than the height of one scaffold above the rest, except in some case of pressing emer- gency. In carrying up any particular part, each side on the right and left should be sloped off, to receive the bond of the adjoining work. - - & When the house the bricklayer is employed upon is intended to have other houses parallel with it, half bricks in a straight line with the front, should be left projecting from every alter- nate course, at the corner or corners to which the addition is intended to be made ; or otherwise, an excavation equal to the breadth of a brick in front, and to the thickness of the wall from front to back, should be left in the alternate courses. In either case, the two fronts will be bonded together, and the gaps, so frequently deforming contiguous houses, when the fronts have been built independently of each other, will be prevented. - Bricks, as a building material, have several advantages over stone; from their porous texture, they unite better with the cement, are much lighter, and the walls built with them are very little subject to damps arising from the condensation of the moisture in the atmosphere. When all materials are ready, a good workman with his labourer will lay a thousand or twelve hundred bricks in one day. Brickwork is measured by the square foot, reduced to the thickness of one brick and a half; thus a wall two bricks thick, ten feet long, and three feet high, and therefore contain- ing only thirty square feet of surface in front, would be called forty feet reduced. It is valued by the rod of two hundred and seventy-two feet. Facing and gauged arches are measured by the superficial square foot; and cornices by the foot running, or length. - V. MAsonry.—Masonry is the term used to designate the art of building with stone, as well as the work itself when executed. - º - - All calcareous stones used in masonry, namely, those that burn to lime. if hard, of a close texture, and beautiful appear- ance, from the variegation, or clearness and uniformity of the colours, are called marble. The names of the different kinds of marble are generally derived either from their colour, or the place where they are obtained. The most valuable kind of milk-white marble is obtained in Italy, and is too costly to be often used for any but the smaller ornamental parts of build- ings. This, when cut into thin slices, is semi-transparent. Many parts of the united kingdom abound with marble, which is mostly more or less coloured, often close in its texture, and capable of receiving a high polish. Derbyshire and Westmore- land, in England, are the counties which supply the greatest quantity and variety of marbles, some specimens of which are highly esteemed. • * When marble that has been faced with a chisel, is intended to be polished, it is ground by rubbing it with rough-grained freestone, assisted by sand and water, until the chisel marks are removed. Finer and fine-grained freestone, with water, but no sand, is then used, till the surface becomes very smooth. If the finer grit-stones be found too slow in their operation, a little fine flour of emery is used. The last and H O U Ho U DICTIONARY, OF MECHANICAL SCIENCE. 475 highest lustre is given with oxide of tin, well known under the name of putty. When the surface of the marble to be polished has been cut with a saw, the very rough freestone and sand are not necessary. In other respects it must be finished by the same process. - - ... " - Limestone is a coarse kind of marble, and is cut and polished in a similar, manner. In many districts, it forms immense strata. From its great hardness, it is only hammer-dressed when used for the fronts of buildings; but when this is done in the best manner, the effect is very fine. . . . . - . The stone most commonly used in London, is Portland stone, which is brought from the island of Portland in Dorsetshire. It is of a dull whitish colour, though thc buildings constructed with it have a handsome appearance. When recently dug, it is soft, and easy to work, but acquires hardness with age. Although it contains silex, the hardness it acquires is not so great that it will strike fire with steel. Under great pressure, Portland stone is apt to splinter at the joints. Purbeck stone is brought from the island of Purbeck, also in Dorsetshire; it is mostly employed in rough work, such as steps, paving, &c. . . Freestone is a general name for stones of very different qua- lities as to their value in building. It consists of clay and silex, sometimes the silex amounts to nearly one-half its weight, but generally it is considerably less, and the hardness of the stone varies with the proportions of its component parts. It is often called grit or sand stone. It is a very plentiful stone; the strata of entire districts, under a slight covering of soil, appearing, in various instances, to be composed of it. The particles of some kinds of it have so little cohesion, that small bits may be granulated between the fingers; this is the sort commonly used for filtering stones. All kinds of it are softer when taken out of the quarry, than they afterwards become when dry, or after long exposure to the atmosphere. Freestone is generally about two and a half times the weight of water. That from Hollington, near Utoxeter, is of a whitish or yellow- ish gray; that from Knipersly, in Staffordshire, is of a bluish gray, and so infusible as to be used as a fire stone. The colour of freestone is often a dull red, but sometimes so nearly -white, that buildings constructed with it look as well as those of Portland stone. Different parcels of freestone, taken from the same quarry, frequently exhibit a considerable diversity of colour; a circumstance which gives a motley appearance to buildings in other respects perhaps faultless. When the stone has been recently dug, and is damp, these differences are often not perceptible. If, therefore, uniformity of appearance be desired, the stones should be faced, dried, and sorted before they are used. . Freestone is incapable of receiving a polish, and therefore, when it has been cut with a saw, it is rarely sub- mitted to any subsequent operation to produce greater smooth- ness; but when it has been reduced with the chisel, it is made smooth with another piece of stone of the same kind, along with sand and water. When the freestone has a laminated texture, it is called flag-stone, and is divided into thin pieces for the purpose of covering houses, and for flooring. The position which stones have had in the quarry, is not a matter of indifference to the attentive mason. Stones intended to sustain great vertical pressure, as pillars, should stand in a building as they stood in the quarry from which they were taken; for pillars, the axis of which were horizontal in the quarry, when placed perpendicularly, are apt to split under a great strain. Perhaps all stones, however solid they may appear, possess more or less of a laminated texture, a pro- perty doubtless occasioned by separate depositions, or crystal- lizations of their peculiar matter. What kind of a pillar any stone well known to be laminated, would produce, in different positions, it is not difficult to conjecture. If, for example, a block of flag-stone were converted into a pillar, so as to leave each lamina or flag of which it is composed posited horizontally, it would sustain any weight not capable of crushing it to atoms; but if the lamina were placed in an inclined position, so as to form an acute angle with the axis, an inconsiderable pressure would occasion them, where the cohesion was slightest, to slide over each other; lastly, if the lamina were placed parallel to the axis, the pillar, under sufficient pressure, would divide vertically into several parts, and though rather stronger than highest degree. | row of stones forms an horizontal surface. in the last instance, would still be comparatively weak. An attention therefore to the position of stones, and to veins or other signs which may indicate the existence of lamina, well deserves the mason’s regard. . - - VI. Of Cements for Masonry.—The cement used by the | mason for the ordinary purposes of walling, is mortar, differing not from that used by the bricklayer; and as we have already treated of this subject rather at length, a few remarks in this place will suffice. For the joints of hewn stone, the mortar should be much finer than the bricklayer requires; and some- times a mixture of oil-putty, or very thick white-lead paint, is used as the cement. These compositions will last longer than almost any stones, and will remain prominent when the face of the softer kinds of stone has been corroded by age. ‘. The cement used in setting column stones, is mostly oil- putty, or white lead mixed with chalk-putty, or fine mortar. Sometimes columns are set upon milled lead; in this case, the lead should not be quite equal to the column in diameter, but so as to leave a narrow ring externally, which must be filled with oil-putty. r : In situations not exposed to damp, plaster of Paris is em- ployed as a bedding for stones or marble. When a mantle-piece is composed of valuable marble, the various pieces are com- monly very thin. In this case, a considerable thickness of plas- ter of Paris is laid on the back, and a slate or some ordinary stone bedded in it, to give greater strength. Good plaster of Paris is scarcely to be met with, nor are the causes of its im- perfections generally understood by workmen. We shall therefore point them out, and give directions for preparing it of a uniform and excellent quality, when we treat of casting ing in plaster. - . The Greeks and Romans constructed their works of wrought stone without cement; but as they used a profusion of cramps and bands of iron and bronze, and the beds of the enormous stones they used were finished with almost mathematical pre: cision, their edifices were substantial and durable in the Metallic bands and cramps are still used in aquatic works, as well as for lofty steeples, and other slender buildings much exposed to the action of the winds, also to connect the different stones composing mantle-pieces, &c. with the wall. - - - 1 . " - VII. Of Stone Walls.-The propriety of erecting suspended or inverted arches, according to circumstances, and other general directions already given respecting foundations, being as applicable to stone walls as to those of brick, need not be adverted to again. The explanation of a few technical terms will therefore be our first object. . . . . Stones which run through the thickness of a wall, in order to bind it, are called bond stones; in some parts of the country they obtain the name of through stones. . - . When the side or sides of a wall lean back, so that the plumb would fall within the base of the wall, the inclination is called battering ; it is generally made about one inch in a foot. . The large stones at the base of a foundation, which project beyond the vertical surface or front of the superincumbent wall, are called footings. . - - The parts of a wall between apertures, or between an aper- ture and the corner, are called piers. . . . . The beds of a stone are its upper and under surface, which are generally in a horizontal position within the wall. i. - Walls built with unhewn stone, with or without mortar, are called rubble walls. Rubble walls are of two kinds, the coursed and the uncoursed. In the coursed, the stones are hammer- dressed or axed, and adjusted by a sizing rule, so that each In the uncoursed, the stones are used in a rough state, nearly as they come out of the quarry. - - Walls which are faced with squared stones, hewn or rubbed, and backed with rubble, stone, or brick, are called ashlar. Wall-plates are horizontal pieces of timber, commonly laid even with the interior of walls, for the ends of the joists and other timbers to rest upon. - The footings of walls ought to consist of the largest stones which can be conveniently procured. It is better to have them of a rectangular form than any other, and if not square, their largest surfaces should be laid horizontally. With this shape 476 H o U H 'O' U DICTIONARY OF MECHANICAL SCIENCE. and disposition, they will make the greatest resistance to sink- ing. If the stones intended to be employed as footings deviate materially from a rectangular figure, when received from the guarry, they ought to be hammer-dressed; as, if they taper downwards, or rest upon angular ridges, they will be apt to give way under the weight of the superstructure. When the footings can be obtained the full breadth of the wall in one piece, they are to be preferred; but when a sufficient number of stones of this description cannot be obtained, then every alternate stone in the course may be the whole breadth, with two stones next to it, disposed like two stretchers in a nine- inch wall of Flemish brick-work. When the largest stones which can be conveniently obtained, are insufficient even for the latter arrangement, the most suitable which can be pro- cured, must be disposed so as to break in the best manner circumstances will admit, the vertical joints in the same course, as well as those of the different courses with respect to each other. Each course, also, should be well bedded in mortar. When bond timber will be required, the uncoursed rubble is an inconvenient mode of building, as the heights on which they are disposed must be levelled. The best kind, or coursed rubble, admits of bond timbers without difficulty, for though the different courses are not of the same height, the surface of each of them is level; but as the walls in which bond timbers are introduced, are apt to warp or even fall in case of fire, the use of them should be avoided in strong well-built walls. The stones of an ashlar front should have their upper and under surface correctly parallel with each other, and correctly at right angles to the face. If these surfaces be carelessly left concave, they will be apt to splinter near the edge under great pressure. On the right and left they should taper inwards, but the taper should not be continued quite to the face, though it may reach the face within an inch or two. The ashlar stones having the form of a truncated wedge, they will in each course present a series of angular indentations within the wall, like the spaces between the teeth of a saw. The stones are so selected and disposed that the vertical or upright joints, and consequently the angular spaces, of one course fall on the middle of the stones below. By this means the ashlar face is bonded to the rubble, brick, or rough stone of the back, and the strength of the wall much greater than if each stone was of an equal rectangular figure. Strength is also to be pro- moted by adopting a plan not commonly regarded, that of sorting the stones, so that in each alternate course they will extend farther into the wall than those of the course immedi- ately above and below. In ashlar work, the bond stones, which ought frequently to be introduced, cannot like the other stones have a wedge-like form; they must be rectangular; and they produce the best effect, when so disposed in each course that they will be opposite the middle of the space between the two bond stones in the course immediately above and beneath them. | VIII. Of Stone Columns.—When large stone columns are made in one piece, their effect, from that circumstance alone, is very striking; but as this advantage is not always obtainable, the next object is to make the joints as few and as minute as possible, as well as to be very attentive in selecting the differ- ent stones to be combined, that the joints may not be described at a distance, by the commencement of a different colour. From what has been said in the section on the different kinds of stone, it will be understood that none but horizontal joints can be allowed in any shaft; all others being inconsistent with the laws of strength. - The stones proper for an intended column being procured, and the order in which they are to succeed each other being determined, the next consideration will be to ascertain the exact diameter proper for each end of every one of them. For this purpose, draw an elevation of the proposed column to the full size, divide it by lines parallel to the base, into as many heights as the column is intended to contain stones, taking care that none of the heights exceed the length that the stones will produce. The working of the stones to the diameters thus obtained then becomes easy. The ends of each stone must first be wrought so as to form exactly true and parallel planes. The two beds of a stone being thus formed, find their centres and describe a circle on each of them. Divide these circles into the same number of equal parts, which may for as the use of a long diminishing rule, when the stones are in: example amóunt to six or eight. Draw lines across each end of the stone, so that they will pass through the centre and through the opposite divisions of the same end. The extre- mities of these lines are to regulate the progress of the chisel along the surface of the stone, and therefore when those of one end have been drawn, those of the other must be made in the same plane, or opposite to them respectively. The cylin- drical part of the stones must be wrought with the assistance of a straight-edge; but for the swell of the column, a dimi- nishing rule, that is, one made concave to the line of the co- lumn, must be employed. This diminishing rule will serve to plumb the stones in setting them. If it be made the whole length of the column, the heights into which the elevation of the column is divided, should be marked upon it, so that it may be applied to give each stone its proper curvature. But many and short lengths, would be inconvenient, rules corre- sponding in length to that of the different heights may be em- ployed with advantage. - Of the different methods which may be practised, to obtain the curvature of the rule to be used in the diminution of the shaft of a column, the following may be considered the easiest and best adapted for general use : Let AB, in the annexed figure, represent the height of the column, ef the semi-diameter of the lower part, and g h the semi-diameter of the A upper part, according to the customary proportion 9Tij of the diminution. As the lower one-third of the - column must be cylindrical, draw a line from e to i, parallel to A B. What we now want is, to obtain a curved line from i, which will fall into g without making the diameter of the upper two- thirds of the column in any point greater than that of the lower or cylindrical third. With the radius ik, draw the quarter of a circle C. Draw a line from the narrowest part of the column, that is, from g, parallel to the axis or middle line A B, till it cuts the quadrant of a circle C. Divide the arc contained between i and the point where 9 cuts C, into four equal parts, as l, m, n, o, and divide the height Ah into the same number of # * divisions as this arc, as 1, 2, 3. From the point Wy 2 #g m draw a line parallel to the axis, which will cut #4 the transverse line 3 at v; from n draw another line .# parallel to the axis, which will cut the transverse Z;2 line 2 in w; in the same manner draw a line from o k] to the transverse line l, which it will cut in a. Now the curved line of the column, between i and 9, must pass through the points a, w, v; therefore at or near all the points from i to g inclusive, drive in two pins or nails, in such a manner that the direction in which each pair of nails stand shall be the same as the transverse lines of the column. - f Between each pair of nails, also, there must be just sufficient space left to admit a thin slip of I5 wood, like a lath, or some other equally flexible - substance, and care must be taken to fix the nails in such a position, that when this slip of wood is placed between them, either its inner or its outer perpendicular sur- face shall exactly coincide with the several points of dimina- tion i, ar, w, v, g. This being done, it is easy, with a pencil or any marking instrument suited to the surface worked upon, to draw a line along the slip of wood, which line will be the curve of the shaft. The piece intended to be used as a diminishing rule may have the curve made on it, or transferred to it, as may be deemed most convenient. It will also be understood, that the number of the parts into which the arc l i, and the height A k are divided, and which determine the number of diminishing points obtained, may be varied at pleasure. In no case, however, can it be considered advisable to make these divisions fewer than four, though for lofty columns they may be made two or three times that number, as they constitute so many checks upon the irregular or imperfect flexibility of the lath or spring rule. As so much of the beauty of a shaft depends upon the easy and impereeptible transition from the cylindrical to the tapering part, it may be advantageous to divide the arc from i to o into two parts, and the division & !, H O U H O U 477 DICTIONARY OF MECHANICAL SCIENCE. of the shaft, also into two parts; a diminishing point will then be obtained between i and a, which will be of use to lessen the possibility of imperfection. Another mode, which we shall recite, of diminishing a shaft, is not essentially different from the preceding : Divide the shaft from D to E, in the first figure, into four parts, as 1, 2, 3; divide the space E F, which is the differ- z. ence between the superior semi-diameter Er, and the inferior or lower diameter D q, into the like ;: number of parts, viz. four. Draw lines from each # division on E F tending to the point D. The first # line next to F will reach to D, the point from which 3 C the diminution commences, in a direction parallel to the axis; the next line, reckoning from the same side, will give the point a ; the third line the point b ; and the fourth line the point c ; a line from the point E, which is the limit of the diminution, need not be drawn. The points E, c, b, a, D, constitute the places where the nails must be driven in, to direct the path of the lath as in the last example. Some artists prefer this mode of diminution: 1. Here, also, as before, the number of the divisions is optional, but a greater error may be committed by making them too few than too numerous. To draw the flutes and fillets on the shaft of a column, the following will be found an easy and effectual method: Let A, in the second figure, be the shaft; make a hole exactly in the centre of both ends, and into each hole drive a piece of wood, so as to be quite tight, and to project five or six inches. The projecting parts b b, of the pieces of wood, must be well rounded off, and made exactly in the middle of the ends. Being provided with a diminishing rule, made as above- mentioned to the curve of the shaft, it may here be used as the ruler, by fixing it in a groove in two pieces of wood. c c, so as to revolve with them upon the pins b b. The edge of the rule must be brought very near the shaft, and one side of it must tend exactly to the centre, which is done by giving that direction to one side of the grooves in c c, as shewn by the dotted lines 3 a. As the diminishing rule d is commonly made rather slender, and there- fore will be apt to bend with the force employed to draw the lines, it will be proper to fix a piece of wood, of sufficient thickness to keep it straight, on the back, or that side of it which does not tend to the centre. As, in marking a long column, there may be some difficulty in keeping the rule steady while the lines are drawn, the strong piece of wood thus attached to the back of the diminishing rule may have one, two, or more screws, according to its length, passing through it, as ff, and pressing against the shaft, by which means the rule will be staid at any part of a revolution, much more effectually than with the assistance of several men. The screws ought to be of wood, or, if iron, their extremities should be prevented from injuring the stone, by the interposi- tion of a flat piece of metal, or some other suitable substance. These arrangements being made, the lines desired may be drawn with any sharply-pointed steel in- strument kept close to the rule, with the greatest ease and precision, from divisions previously marked at one end. To obtain these divisions, suppose it were desired to flute the Ionic, the Corinthian, or Compo- site columns, the circumference at one end will be divided into six equal parts, by taking half the diame- ter at that end, and applying it round the said circumference; and if each of these divisions be divided into four, the whole circumference will be divided into twenty-four. In order to make the proportion of a flute to a fillet as one to three, divide any one of these last divisions, or twenty-fourth part of the circumference, into four equal parts, and one of these parts will be the breadth of a fillet; which being set off from the same side of each division, the whole shaft will be properly divided for flutes and fillets, and consequently prepared for the use of the rule. To draw the flutes and fillets on a diminished pilaster, make a line down the middle of the face of it, from top to bottom ; divide this longitudinal line into any convenient number of equal parts, and through the points of division draw transverse lines crossing the breadth of the pilaster; set off the flutes and fillets on each transverse line ; fix pins or nails at each cor- responding point of the transverse line, and draw the lines with the help of a pliable slip of wood, as in obtaining the diminution of a shaft. IX. Stone-bridges have been explained. See BRIDGes. MISCELLAN Eous REMARKS RELATIve to BUILDING. Under this title, we shall include a variety of particulars, either not belonging, or not exclusively belonging, to Masonry or Bricklaying. Under the first head of this subdivision of the chapter on Building, the earliest notice seems due to a sketch of the general rules proper to be observed with respect to the X. Situation and Plan of Houses. See ARchitectURE.— With respect to situation, when the person who is intending to build enjoys the advantage of choice, the proximity of marshes, fens, of a boggy soil, or stagnant water, should be avoided. If a river be very near, the site of the house should be on ele- vated ground, so as to be out of the reach of the unwholesome fogs and mists arising from it early in the morning. A neigh- bourhood where cattle thrive, and where the inhabitants are healthy and cheerful, or are remarkable for their longevity, may be regarded as possessing a salubrious air. The most essential requisites of a good situation, or those which are most con- ducive to health, being obtained, minor advantages may be regarded according to their importance. Abundance of water, fuel, and ways of easy access to arrive at the house, are con- veniences of lasting value. The advantages of a situation, with regard to prospect, are of a more problematical nature, as they are so differently valued by different persons. A man of taste will, however, undoubtedly prefer a spot, the prospect from which is most agreeably diversified in the distribution of its land, wood, and water; and those who have little or no relish for the charms of nature, will perhaps consult their own comfort more than they may be aware of, by making the same choice. There are very few so obstinately morose, as to be uninfluenced by the opinions of others; and to observe those about them, particularly visitors, warm in their admiration of the surrounding scenery, may create a beneficial complacency which they would otherwise want. - Trees at a little distance from a house are better than hills, as they yield during the day, in summer, a cooling, refreshing, sweet, healthy air; and, in winter, break and diminish the keenness of the winds. Hills on the east and south side are the most inconveniently situated. If the site of a house be low, the first floor should be set so much the higher. Cellars contribute to the dryness of a house, if the ceilings and floors be good. With respect to the situation of the parts of a house, the studies, libraries, and chief rooms, particularly the bed-cham- bers, should face the east; those offices which require heat, as kitchens, brewhouses, bakehouses, and distilleries, should have southern aspects; and those which require a cool fresh air, as cellars, pantries, dairies, granaries, a northern one, which is also proper for galleries, paintings, museums, &c. which require a steady light. When a situation has been fixed on, the plan and elevation of every part should be made by some person well acquainted with the theory and practice of building. A skilful architect will not only make the structure handsome and convenient, but will save the great expenses often incurred in rectifying the blunders of hasty and injudicious management. For a small building, the elevation of each front, with a plan, may indicate, with suf- ſcient correctness, its ultimate advantages; but for a Jarge 6 F * 478 H O U. H O U DICTIONARY OF MECHANICAL SCIENCE. mansion, or structure of any description, consisting of many complex parts, the most certain way to prevent mistakes, is to hav, a perfect model of the whole made to a regular scale. In order that such a model may not mislead the judgment by pleas ing the eye, it should be made of plain wood, of one colour. Lodges and small houses, standing alone, have an agreeable appearance when of a cubical figure; but large mansions of this shape look rather clumsy; an oblong is therefore commonly preferred, care being taken not to make the plan so long as to lose much room in the passages which will be required, and which will be difficult to light. When the length of a mansion does not exceed the breadth more than one-third, the propor- tion is good. - XI, Of Rooms.-The principal objects to be regarded in the arrangement and proportions of rooms, are doubtless those of conveniency, and their adaptation to health. Rooms, the plan of which are rectangular, give the greatest facility to conveni- ence of arrangement, without the disadvantage of losing the space rendered unavoidable by adopting circular or other curved forms ; but with regard to health, the height of a room should at least be ten or twelve feet, and this point should be regarded even in apartments too small to render such an ele- vation proper in an architectural point of view. A square is an agreeable form, but is most proper for rooms not exceeding a moderate size, as it cannot well, if very large, be completely lighted from one wall, and the company, while ranged on each side, are too far apart. For spacious apartments, a rectangular parallelogram or oblong is a more convenient figure, and, with regard to beauty, every variation in the proportion, from nearly a square to a square and a half or sesquilateral, may be employed. If the length of the plan be extended materially beyond a sesquilateral, the apartment obtains rather the appearance of a passage or gallery, and it becomes impossible to adjust the height so as to suit both the length and breadth. In square rooms of the first story, the height may be from four- fifths to five-sixths of the breadth of the side ; and in oblong rooms, the height may be equal to the width. An error in favour of height; is preferable to making a room too low. The height of rooms on the second story may be one-twelfth part less than that of the chambers below; and if there is a third story, divide the height of the second into twelve equal parts, of which take nine for the height of such rooms. An eligible length for galleries is five times their breadth, and they should rarely exceed eight times their width in length; their height may exceed their breadth in the proportion of a third or even three-fifths, according to their length. r As, however, in modern houses, all the rooms of the same story are commonly of the same height, and convenience re- quires them to be of different sizes, according to their use, it follows that the best proportion of the height to the other dimensions, cannot always be observed, without incurring Some extraordinary expense. Where expense is not a hinderance, the height of the story may be suited to the principal rooms, and the middle-sized rooms may be reduced by covering the ceilings, with a flat in the middle, or by groins or domes, which will add to their beauty, independently of bettering their pro- - - | called jambs. portions. - Precautions should be taken to prevent the effluvia from the kitchen, brewhouse, and other offices, from penetrating to the bed-chambers and dining rooms. The most difficult object to attain of this description, is to prevent the effluvia of the kitchen from annoying the dining-room, to which the access from it should be as easy and short as circumstances will allow, for the convenience of the servants waiting at table. In country mansions, which admit of the greatest liberty of plan, and where the kitchens are above ground, this may generally be done by such an arrangement of the doors and passages of communication, that no current of air from the kitchen can proceed directly towards the dining-rooms. But in town houses, where the kitchen is beneath the parlour floor, and therefore not only far nearer in point of situation (though not perhaps of access for persons) than it is usually placed in the country; but on a lower level, the lighter warm air, charged with the smell of the various operations of cookery, is apt to be felt above, from its disposition to ascend. It may, how- ever, be effectually removed by a small separate funnel, carried up in the stack with the rest, and next to that of the kitchen. This funnel, to be used for no other purpose, must have its throat or lower opening level with the ceiling of the kitchen. The lighter air, charged with the vapours of the cooking, will then pass off into the external atmosphere by this aperture, instead of accumulating under the ceiling of the kitchen, until it forms a stratum as low as the top of the kitchen door, and then ascending through the house by the stairs and passages. The opening of this funnel or pipe may be closed by a hinged door, when no operation is going on in the kitchen which can create a disagreeable smell. - - Every chamber in a house should, if possible, have a fire- place, the place of which, in those employed as bed-rooms, if they are not very spacious, should be about two feet or two feet and a half out of the middle, to allow room for the bed. In apartments of twenty or twenty-four feet a side, this arrange- ment need not be studied, as the bed can without it be placed sufficiently far from the fire. ... * XII. Chimneys.-That no apartment can be comfortable which is incommoded with smoke, will not be contradicted; yet we find a very general disregard of the precautions which would secure a strong draft up the chimney. Masons and bricklayers follow their own fancy or judgment, which are often influenced by their convenience, or by local customs, with little regard to rational principle. It frequently happens that the smoking of chimneys is occasioned by their being carried up narrower at the top than below, or by their having one or more sharp angu- lar turns. When chimneys are constructed in a pyramidal or tapering form, and are besides left rough or unplastered, with stones or bricks projecting into them, as well as the mortar pressed from the joints in the wall, their smoking is almost certain. The air, rarefied by the fire, passes up a chimney with the smoke; but as it recedes from the impelling power, or fire, it moves slower, and requires a greater portion of space to circulate through ; if then, the upper part of a chimney, instead of being wider than below, be contracted, and if the roughness of the walls concur at the same time-to increase the obstruction, it is no wonder that the smoke, taking the path of least resistance, should find its way into the room, whenever assisted by a current from above. If may be urged, that a chimney wider at the top than below, allows the wind more liberty to blow down; but it must be considered, that the wind having no adequate resistance from above to overcome, must necessarily return, and thus facilitate the free egress of the smoke. On the other hand, when a current of air rushes down a pyramidal chimney, it becomes confined or wedged in, and if urged by a constant wind, the rarefied air from the fire cannot make head against it, and therefore the smoke bursts into the TOOIA. - - Experiments, in endless variety, and often at great expense, have been made to prevent or cure smoky chimneys; we shall notice some of the most simple and efficient; but it will be proper to explain, in the first place, some of the terms which are used in speaking of chimneys. The aperture from a chim- ney into the room, is called the fire-place. The projecting parts of the wall, on the right and left of the fire-place, are The head of the fire-place resting upon the jambs, is called the mantle. The mantle, and the whole side of the chimney above it up to the top, are called the breast. The side of the chimney, called the breast, being pointed out, the application of the term back, to the opposite side, explains itself. The sides of the fire-place contained between the jambs and the back are called covings. The throat is that part of the opening immediately above the fire, and contained between the mantle and the back. When chimneys are bounded on the top by a zigzag line, so as to resemble the teeth of a saw, they are found to be far less liable to smoke than those in other respects under the same circumstances; and in a great variety of cases, the cheap and easy expedient of altering the tops of smoky chim- neys to this form, has been attended with complete success. The partitions in a stack should be indented as well as the out- side wall. The fire-place is generally an exact square. Its height, in large rooms, is often very properly made less than a square, and in small rooms, particularly when the chimney is in a H O U H O U 479 DICTIONARY OF MECHANICAL scien CE. corner, it is rather more. In rooms from twenty to twenty- four feet square, or of equal area, it may be from four feet to fous feet and a half broad: in rooms from twenty-four to thirty feet square, it may be from four and a half to five feet; and in rooms still larger, it may be extended in a similar proportion to six feet. If much beyond six feet, whatever may be the size of the room, the effect will not be good; for if the fire be proportionate, it will excite rather the idea of a furnace. Two fire-places will certainly be better than one of such overgrown dimensions. As to the effect of the form of this aperture on the draft, its breadth is not very im- portant, provided it be not so narrow as to prevent the cowings from standing with their greatest power of reflection towards the room ; but the height should seldom exceed two feet six inches to the under side of the mantle. The throat should not be more than four or five inches wide; but should be contracted by a part moveable at the back, when the chim- mey requires sweeping. The nearer the throat is brought to the fire, the stronger the draft will be. For fire-places about three and a half feet wide in front, the flues of chimneys, above the throat, are usually made equal to about twelve inches square; and the general rule is, to make the area of the hori- zontal section of the flue equal to the area of the horizontal section of the fire. If the flue were smooth and circular, this mode of proportioning its size would doubtless be found to allow it unnecessarily large. Where bends are required in a flue, they should be in a curved, and not an angular direction. High chimneys always draw better than low ones, as, in pro- portion, to their length, the influence of the wind extends a shorter way down them. An apartment made wind-tight, by listing the doors and other contrivances, is liable to be incom- moded with smoke, from the want of draft, even when the chimney is constructed in the most proper manner: a few minute holes, communicating with the exterior, will, in such cases, constitute an effectual remedy. Another method of increasing the draft of a chimney, con- sists in setting the grate, if a Bath stove, eleven or twelve inches from the fender; and in cutting away the back of the chimney, so as to leave a space of two inches between it and the back of the grate. If the grate be of the common form, the sides should be filled up with brick work. By this con- struction, the air that passes behind the back of the grate, as- sisting to impel the smoke, prevents its bursting into the room. | —That a chimney clogged with soot will be apt to smoke, is so Well known, as to require no notice here. - The evils attending the practice of cleaning chimneys by means of climbing boys, are of the first magnitude. The degraded situation of the children in this employment, so destructive to health at any period of life, but especially in early youth, has often and strongly excited the commisera- tion of philanthropical men, and many schemes have been Proposed to render their ascending unnecessary, and thus abolish a practice so offensive to humanity. Of these plans, the most feasible consists in the use of brushes, which are drawn up and down by men at the top and others at the bottom, or are pushed up from the bottom, and drawn down by persons within the apartment. The former method is inconvenient and expensive ; the latter, which is the inven- tion, of Smart, is often practised, and has justly received much approbation. The rods by which the brush is pushed upwards, are made hollow and in short lengths, and are con- nected together by a cord passing through them. As soon as the lower end of the first rod is pushed about the height of the mantle, another rod is slipped over the cord, and the length- ening of the whole is thus continued, till the brush clears the top of the chimney, where it spreads itself out, and is prevent- ed from contracting by a spring; so that the soot is brought down along with it. But as long as the practice is continued, of making chimneys square, crooked, and rough, it is to be feared that no sweeping apparatus can be contrived which will be found completely successful. Inventions recommended solely by their humanity, are often so slow in their progress towards general adoption, that an eminent service will be rendered to *9%iety, by the man who makes the convenience and interest of individuals conspire with their benevolence, to promote the purpose before us. Amongst the various improvements of modern times, per- haps few have been more really beneficial than the use of metals, for purposes to which, only half a century back, they were hardly thought applicable. It is perhaps not generally known that the great variety of articles of fittings now con- stantly kept in ironmongers’ shops, in the remotest villages, were hardly known in country places at the beginning of the last century; but wherever a house was built, its bolts and latches were mostly of wood; its windows, if sashes, were mas- sive, and if one sash ran, the sash-cord ran over a wooden pulley; and many other minute fittings were either of wood, or, if of metal, were individually made by the adjacent smith, who produced a clumsy article at a great waste of time and labour. We now see the use of iron and brass extensively superseding timber and stone in the most advantageous man- ner. At Eaton Hall, the magnificent mansion of Lord Grosve- nor, near Chester, the tracery of the windows, many shields, a stair-case, and a variety of ornaments, are of cast iron. A large portion of tracery pannelling, for a terrace balustrade, are of the same material, and being painted and sanded, have all the beauty of stone. Hollow Grecian balustrades, for a public building in Ireland, have been made of iron, in Liverpool. Two patents have been taken out for roof framings of iron, one of which, at least that of J. Cragg, Liverpool, is particularly remarkable for its simplicity, and the beauty of its execution. This gentleman also executes stair-cases of iron, in so accurate a manner, that they may be put up at any place in a few hours. Cast iron bridges have long been deservedly celebrated, and the dearness of wood, and the supposed inefficiency of the patent stone pipe, have caused cast iron water-pipes to be used in London, and many other places. Cast iron has also been advantageously used for beams and their supports in a large way, the Trustees of the Duke of Bridgewater’s canal having used it for beams in a new warehouse at Liverpool, of more than thirty feet clear span ; and the Carron Company have used some excellently arranged hollow iron stanchions in a new warehouse at Liverpool. Rennie employed it abundantly in the warehouse of the London docks; and its use in aque- ducts and bridges is now proverbial. - There is yet another purpose, for which iron seems so well adapted, that it deserves at least a fair trial ; it is that of cast pipe for chimneys. The present mode of building chimneys is not only extremely unsafe, but also takes up a great deal of room ; and from their being square, there is a great difficulty in cleaning them thoroughly, except by climbing boys, or, as is frequently practised, by purposely firing them. Smart’s appa- ratus does not completely answer, because the corners which contain most soot do not get swept completely, and are often not touched. Another objection to ordinary brick square chimneys is their smoking, or, in other words, not drawing ; an evil not considered, by those who suffer from it, of the most trivial magnitude. All these inconveniences might be remedied by using for chimneys cast iron pipes three-eighths of an inch thick, and when once the utility of the plan became known, the article would become as common in iron shops as fronts of grates. The present openings into the room are built far too large, and are now generally contracted by various means when the grate is set, but while the present arrangement of brick chimneys for climbing boys remains, they cannot well be much altered ; but if iron pipe were used, an iron fire-place top would be cast for the pipe to fit into, and would of course be made of various sizes and shapes like grate fronts, and iron articles, in general, cast by the Carron Company and other founderies. - More clearly to exemplify the advantages of this invention, it will be proper to detail the arrangements necessary. Pre- judice will at first perhaps require the pipe to be eight inches in diameter, though there is little doubt that seven, six, or even five inches diameter would be amply sufficient for the largest fire. However this may be, it should be cast in lengths of from three to five feet, which, at three-eighths of an inch thick, would render the pieces of a manageable weight; they should be carried up as close as possible to each other, and as four inches of brick-work is more than enough on each side of them, in walls of two bricks thick, they would cause no projection into the apartment. The interstices between 480 H O U H O U DICTIONARY of MECHANICAL scIENCE. 2^ / * | the bricks and pipe should be filled with earth, or, what g would be still better, rubbish and liquid cement. A bevel || joint, a, in the figure, might be made to the pipe, to fit so closely that no crevice would be left to lodge soot, when the cement surrounded the exterior. If one, or indeed all the chimneys in a stack, constructed upon this plan, were to get on fire, it would be of little conse- quence, as the heat could never be so great as to act through the pipe and such a solid mass as the stack would be. The soot would not lodge in such chimneys as in the common ones, for in a round chimney the draft would clear more smoke out of the chimney before it was condensed; and when they required cleaning, Smart’s apparatus would sweep them com- pletely.—When a house with ordinary chimneys is burnt, the stack usually falls down, tearing the walls, and rendering it necessary to rebuild them; but if a house with an iron-pipe stack was burned, it would not only in all probability stand, but act as a buttress to sustain the walls: or, in case it fell, the greater part of the pipe would remain as fit for use as at first. Although it may be least trouble generally to leave the breadth of half a brick round the pipe, yet, in small buildings, and in cases where room is wanted, a flat brick would, there is no doubt, be quite sufficient for all purposes of safety. In all Čases, too, where iron pipe may be used, the labour of plaster- ing chimneys will be saved, which, though in many places omitted, is done to all well-built houses. The saving of room which would be produced by the use of iron-pipe, in a stack of four eight-inch chimneys, will be im- mediately seen by the inspection of fig. 1; and fig. 2 exempli- fies the same thing with respect to a stack with five chimneys. I’ig. 1. , 3ft. 9 in. 4ft. 10; in. § - § ‘ā| COOO || || 's .S - i !---, •S - *º CO CNº. CN *: Projection into the Room, four and Projection into the Room, nine inches, a half in. if one and a half brick wall. if one and a half brick wall. Fig. 2. 4ft. 6 in. 6 ft. OOOOO - Af * - .# Projection nine and a hałf inches, if oxe and a kalf brick 20all. . i Projection four and a half inches, if one and a half brick wall. If nine inches be allowed for the exterior diameter of the pipe, (and such an allowance will be enough for all contingencies,) it may be carried up, in all walls exceeding two bricks thick, without any projection into the apartments. In the corners of a two brick, or even a one and a half brick wall, there is suffi- cient room to carry up such a chimney, which would rather in- crease than diminish the strength of the wall, since nearly one- half of the space taken up by chimneys in the common way will be saved, under circumstances the most unfavourable to shewing . the advantages of the new plan; for the diameter of the pipes. is reckoned at the largest that can be required; and the brick- work surrounding the square chimneys, at the thinnest it can with any propriety be made. The expense of round work, either in brick or stone, is pro- bably the principal reason that round chimneys are not in general use, though she advantages of them, particularly in being free from the currents or eddies of air occasioned by | For example, suppose the room to be forty feet long, thirty square chimneys, are not unknown to intelligent builders. Oval flues might be recommended as perhaps superior to the circular ones; for there are many situations in which they might be carried up advantageously with the conjugate diameter of the ellipse running parallel with the gable of the house, or the reverse. Iron pipe, it is well known, answers perfectly well for stoves, and the portable furnaces of chemists, although the area of it is seldom more than half that of the fire, and the quantity of air required to maintain the vehement heat which can be exci- ted at pleasure, occasions a much greater draft than that of ordinary domestic fires of twice the size. Hence the above adequateness of which is already proved. i one, which is then made in the most convenient place. gº plan only proposes to extend the use of a kind of chimney, the X- XIII. Doors.-The ancients, according to Vitruvius, fre- quently made their doors rather narrower in breadth at the top than at the bottom. . These trapezoidal doors were probably adopted from their having the property of closing themselves, and in modern times they are useful besides as the simplest mode of raising the door, in the act of opening, above the floor, in order to keep it clear of the carpet. There are examples of them in the Bank of England; but they are not often intro- duced by architects. f - Doors are varied in their dimensions according to the height of the story and the magnitude of the building in which they are placed. In private houses, they can rarely with propriety be made wider than four feet, and in general three feet will be "sufficient. For small doors, when the height is to the breadth in the ratio of seven to three, the proportion may be con- sidered good; but the height of large doors need not be more than double their breadth. The entrance doors of palaces and the mansions of noblemen, where much company resort, are often made from four to six feet wide ; and those of public edifices may be from six to ten feet wide. Doors much ex- ceeding three feet in width, should have folding leaves. In modern houses, it is not uncommon to have large folding doors, the opening of which serves, instead of removing a whole partition, to throw two rooms into one. In such cases, the width of the aperture will generally be of less height than twice its breadth, as all the doors of the same story are com- monly of the same height. * { When the principal door of entrance is in the middle, its communication with every part of the building is not only the most readily effected, but it contributes so much to the sym- metry of the front, that when the plan renders such a position inadmissible, a blank door is frequently substituted for a real The entrance doors of stately houses are frequently adorned with porticoes, in the Grecian or Roman taste; but the most com- mon mode of adorning entrance doors, is to surround them with an architrave, surmounted with a cornice, or with a frieze and cornice forming a conspiete entablature. These decora- tions are made of stone, wherever a suitable kind can be had | at a reasonable price. XIV. Windows.-In determining the number and size of windows, regard must be paid to the destination, local posi- tion, and elevation of the building, as well as to the cubature and height of the story in the rooms to be lighted, and the thickness of the walls. With respect to private houses, though considerable latitude may be allowed in the determination of this subject, still there are limits which cannot be disregarded without losing the beauty of proportion, and the convenience of a due quantity of light. In general, the piers should not be of less breadth than the apertures, nor more than twice such breadth. The windows, in all the stories of the same aspect, should be of the same breadth, unless a variation be required from this rule for the convenience of particular offices in the lowest story. The laws of symmetry and strength alike re- quire them to be exactly one above another; this practice, so strangely neglected by our ancestors, is now, indeed, duly attended to. The apertures of windows should widen inwards on each side, by which means the quantity of light admitted will be nearly as much as if they were externally of the same size as the increased internal dimensions. . - To determine the aggregate area of the windows proper to be made in an apartment, extract the square root of the cuba- ture of such apartment, and the quotient will be the answer. feet broad, and sixteen feet high, then 40 x 30 × 16 = 19200, which product is, in feet, the cubature sought, and the square root of it, neglecting a small remainder, is one hundred and thirty-eight feet for the aggregate area of the apertures. One hundred and thirty-eight feet will make four windows of a handsome size and shape, adapted to the apartment in ques- tion; and if divided accordingly into four parts, thirty-four feet and a half will be the area of one of them. The area thus ob- tained, when set out for a ground floor, according to the cus- tomary rule, which allows gather more than two squares in II O Ú H o U 481 DictionARY or MECHANICAL scIENCE. height, each window may be about eight feet eight inches high, by four feet broad. By the same rule, the dimensions of the apertures of windows for rooms of any other cubature may be determined. - - - The sills of windows have been mostly made from three feet to three feet six inches distant from the level of the floor, as at that height they formed a convenient parapet to lean upon; but the French fashion having been introduced, of hav- ing the windows, at least in the principal drawing-rooms, down to the floor, window-sills are now, partly in imitation of it, made lower than formerly, and in ordinary dwellings are fre- quently not higher than two feet, and in the extreme not more than two feet six inches. It will be proper to remind those who are partial to spacious and numerous windows, and who are not disposed to modify their choice by motives of economy, that as the aggregate area of the windows is enlarged, it becomes increasingly difficult in winter to keep apartments warm, the heat produced in them being so very speedily communicated through the glass to the atmosphere without. It is for this reason, that in Russia they often make their windows double, and as air is a bad conduc- tor of heat, the stratum of it interposed between the two win- dows in the same frame, tends very materially to prevent the temperature of the room from being carried off. The cold sea- son is not so severe, or of such long continuance, as to have occasioned the introduction of this practice for front windows into the United Kingdom, but it might be advantageously acted upon with respect to the skylights employed to light staircases, as such windows, when only single, contribute greatly to the speedy dissipation of the warm air which ascends to the top of the house. - - The number of windows on each side of the entrance door should be equal, and an odd number of windows in an apart- ment, when they are all on one side of it, is better than an even number, as it avoids the necessity of having a pier oppo- site the middle of the floor. g The windows of the principal floor are generally the most enriched. The simplest mode of adorning them is, to surround them with an architrave, which sometimes has, and sometimes is left without, a frieze and cornice; frequently the whole of the windows are left plain, except the central one of the second story. When the windows of the principal story have pedi- ments, those of the story immediately above should have archi- || traves surmounted by a frieze and cornice, and those of a next higher story, an architrave only. The sills of all the windows in the same floor should be on the same level. XV. Stairs. See HANDRAILs.--To unite the requisites which a good staircase requires, namely, convenience in situation and form, with a sufficiency of light, affords one of the strongest proofs of an architect's skill. In stately mansions, the steps should not be less than four, nor more than six inches high; nor more than eighteen or less than twelve inches broad; and the width should not be less than six or exceed fifteen feet. In ordinary houses, the steps are generally made higher, and are almost necessarily narrower, both in width and length; but, while any thing like handsomeness of appearance and conveni- ence of ascent are studied, they should not exceed seven inches in height, nor be less than ten inches broad, and three feet long. Stairs are ascended with more ease when laid somewhat sloping, or a little higher at the back. The ancients were par- tial to an odd number of steps; one consequence of which choice was, that the same foot which was placed on the first step was first placed at the top on the landing. XVI. Roofs.-Architects include, under the term roof, not only the exterior covering of a house, but all the beams and other parts necessary to support that covering. . Among the ancients, in those countries where it seldom rained, roofs were made quite flat; but the Greeks, perceiving the inconvenience of this form, deviated from it a little, by inclining their roofs, as appears from several ancient remains, about one-eighth or one-ninth part of the span. The Romans, who had rather more occasion than the Greeks to provide for the speedy discharge of rain from their houses, made the height of the inclination of their roofs from one-fifth to two- ninths of the span. Among the northern nations of Europe, after the decline of the Roman empire, high-pitched roofs measure, with respect to this point, similar to slate. began to be in general request, and that was considered the standard form, the vertical section of which was an equilateral triangle. No part of the art of building has been more sub- ject to caprice, than the height of the inclination, or, as it is usually expressed, the pitch of roofs. In the present day, a great variety of pitch is employed, but the equilateral one is seldom seen. In ordinary dwellings, the pitch of the roof is from one-third to one-fourth part of the span ; but mansions and public edifices are still executed in every diversity of style that fancy or particular views can dictate. * High-pitched roofs discharge, rain and snow more quickly than others; they are also not so easily stripped by the wind; the rain is not so easily blown between the slates, and from their approach towards perpendicularity of pressure, they are not so great a burden to the walls. They are, however, more expensive than low roofs, as they require longer and stronger timbers ; and from their greater surface, they require a larger quantity of the covering material : but though low roofs have the advantage in point of cheapness, they require large slates, and great care of execution. - - The roof is one of the principal ties of a building, when skil- fully executed, in connecting the exterior walls. Some idea may be formed of the success with which scientific knowledge and experience may be employed in the construction of roofs, when it is observed, that roofs have been constructed sixty feet wide, although they have not contained a single piece of timber more than ten feet long and four inches square. * . . . . In determining the pitch of rafters, when mere fancy is not to be our guide, the nature of the intended covering should be taken into consideration, and the inclination proportioned accordingly. The following rules may be observed with prorpiety :— - For Lead.—Divide the width first into two parts, as in the annexed figure, and one of these parts into four, as 1, 2, 3, 4; with two of these parts describe a quarter circle, 2, which gives a proper pitch or slope to be covered with lead, and is called a pediment pitch. For Pantiles.—Divide the width as before into two parts, and one of these two parts into four, as 1, 2, 3, 4; with three parts, describe a quarter circle, 3, which gives a proper pitch for use. For Plain Tiles.—Divide the width into two parts; with one of them make a quarter circle, which gives a pitch, or slope proper for the roof. The lighter the covering material, the lower the roof may be, and therefore the pitch for slates may be the same as that for the covering which the particular quality used most nearly approaches to in weight. Tiles, though extensively used in many parts of the country, constitute a very heavy covering for houses, and, what is still worse, they injure the timber upon which they are laid, and tend to make a house damp, from the facility with which they are penetrated with moisture. The following experiment, by the bishop of Llandaff, decisively proves their great porosity, and their inferiority to slate. The Bishop observes, that sort of slate, other circumstances being the same, is esteemed the best, which imbibes the least water; for the imbibed water not only increases the weight of the covering, but in frosty weather, being converted into ice, it swells and shivers the slate. This effect of frost is very sensible in tiled houses, but is scarcely felt in those which are slated ; for good slate imbibes but little water; and when tiles are well glazed, they are rendered in some He took a piece of Westmoreland slate, and a piece of common tile, and weighed each of them carefully; the surface of each was about thirty square inches. Both the pieces were immersed in water for about ten minutes, and then taken out and weighed as soon as they had ceased to drip. The tile had imbibed above a seventh part of its weight of water; and the slate had not im- bibed above a two-hundredth part of its weight; indeed, the wetting of the slate was merely superficial. He placed both the wet pieces before the fire; in a quarter of an hour the slate was become quite dry, and of the same weight it had before it was put into the water; but the tile had lost only about twelve grains of the water it had imbibed, which was, as nearly as could he expected, the very same quantity that had been spread over e = ** ,” * * ... 3 º ż 6 G. 482 H o U H o U DICTIONARY OF MECHANICAL SCIENCE. its surface; for it was the quantity which had been imbibed by. the slate, the surface of which was equal to that of the tile. The tile was left to dry in a room heated to sixty degrees, and it did not lose all the water it had imbibed in less than six days. If, then, tiles imbibe a seventh part of their weight of water in ten minutes, and cannot be deprived of this water without a degree of heat equal to sixty degrees continued for six days, it must be obvious that a roof covered with them, can, in this country, seldom be dry. The timbers also of the rôof must be calculated to support their weight in their wet state. t The finest sort of blue slate, which is obtained in the neigh- bourhood of Kendal, is sold there for 3s. 6d. per load, which comes to £1: 15s. per ton, the load weighing two hundred weight. The coarsest sort may be had for 2s. 4d. per load, or £1.3s. 4d. per ton. Thirteen loads of the finest sort will cover forty-two square yards of roof, and eighteen loads of the coarsest sort will cover the same extent. Hence there is half a ton less weight upon forty-two square yards of roof when the filiest slate is used, than when it is covered with the coarsest kind, and the difference in the expense of the material is only 3s.6d. ; yet as fine slate owes its lightness, not so much to a difference in the quality of the stone from which it is split, as to the thinness to which it is reduced, it is inferior to the heavier kind in point of durability. The following statement shews the average weight of the covering laid upon forty-two square yards of building, accord- ing to the material employed — * . . . . . Copper.......... 4 cut. Coarse slate .... 36 cwt. Fine slate . . . . . . . 26 | Tiles . . . . . . . . . . . . 54 Lead. . . . . . . . . . . . 27 Such are the advantages of slate as a covering, that wherever it can be procured without much land carriage, it obtains the preference of all other materials. Its durability is so great, that it has been known to continue sound and good for cen- turies; but all kinds of it are not equally excellent in this respect. Its most usual colours are white, brown, and blue, and the colour affords some index to the quality of the slate. The light blue sort is always the least penetrable to water, which the deep black blue is apt to imbibe rather freely. Several methods may be practised to ascertain the goodness of slate, when not brought from a quarry of well-known character. If a slate, when struck sharply against a large stone, produce a complete sound, it is a mark of goodness; and if it does not shatter before the edge of the zax, or instrument used for hew- ing it, the criterion is decisive. Another method is, to place the slate lengthwise and perpendicularly in a tub of water, about half a foot deep, care being taken that the unimmersed part of the slate be not in any way accidentally wetted. Let it remain in this state twenty-four hours: at the end of that time, if the slate be good, it will not have drawn water more than half an inch above the surface of that fluid, and that per- haps at the edges only, where the texture has been a little loosened in the hewing; but a spongy defective stone will draw water to the very top. Another mode of trial, on the result of which full reliance may be placed, is to weigh two or three of the most suspected slates, and note their precise weight; then immerse them entirely in water for twelve hours: take them out, wipe them as clean as possible with a linen cloth, and if their weight differs not, or differs but very little from what it was at first, they may be considered good; a drachm in a dozen pounds is allowable, but not more. The principal reason of the inferiority of the slates which imbibe much moisture, being that they are shivered by frost; when none but a porous kind can be easily obtained, they might doubtless be improved by the application of tar, as already mentioned for tiles, when treating of the manufacture of the latter article. Among the artificial methods that have been invented for covering houses, a composition called tessera was a few years since in high repute. It consisted of tar, calcareous stone reduced to dust, and a little powder of burnt bones. ingredients, duly mixed, were spread into sheets made equally thick, about four feet long and two feet wide, by passing under rollers; and when laid on the boarding of the roof, which might be either flat or angular, the sheets were cemented by a solder of the same materials. --- These . When this composition first gained public attention, it. was thought to be of incalculable value. It was said to be lighter than lead, to be considerably cheaper, to equal it in point of durability, and though apparently combustible, to be tºle of resisting the effects of heat about twice as long as lead. -- w * * To secure the advantages of this important discovery, a patent was taken out by the inventor, December 22d, 1806, and agents were appointed throughout various parts of the kingdom. The confidence of builders was soon gained, and many houses were covered with this promising compound. Experiment, however, which is the best test of excelleace; soon detected the fallacy of theory, and those who had put- chased tessera speedily found that they had laid out their money in buying a stock of repentance. It was shortly per- ceived, that it could not withstand the corroding influence of the seasons, that it would alternately swell and crack accord- ing to the temperature of the weather, and thus readily admit the rain, which it was expected to exclude. Having thus lost its character, it soon fell into disuse. Many houses that had been covered with it, were forced to be stripped, and to receive the old but partially discarded materials; and tessera having lived its day, is now known only in name. XVII. Floors.—Flooring boards are mostly made of fir. The first class are selected free from knots, shakes, sap-wood, or cross-grained stuff: the second class consists of boards also free from shakes and sap-wood, but not from small sound knots; the third class contains the residue of any parcel, or such boards as cannot be included in either of the preceding classes. When an agreement is entered into for the erection of a building, the quality of the boards should be specified, to prevent subsequent disputes. As all boards shrink in the course of time, and as the quantity of their contraction increases with their dimensions, floors which are laid with very broad boards soon exhibit, at the joints, wide fissures that have an unpleasant appearance. It is therefore the practice in good' houses, not only to select the best part of the wood, but to cut the boards into narrow scantlings; so that, if properly sea- soned, and laid close at first, their shrinking afterwards is so, small as to make no openings of consequence. Boards about five inches broad may be reckoned narrow, but when they measure nine inches or more in the same direction, they must be con- sidered broad. - . The manner of jointing flooring boards, and fastening them down upon the joists, is performed in a variety of ways, the most usual of which is, to plane the edges of the board quite square, that is, at right angles to the upper and under surface, and then, placing them as closely to each other as possible, to nail them down from the upper surface. Sometimes, par- ticularly when the wood is known to be insufficiently sea- soned, after the first board has been fastened down, the fourth board is secured in like manner, the two intermediate boards are then made somewhat wider than the space to receive them, and forced into their places by jumping upon them. To do this with the most ease and advantage, the intermediate boards are laid aslant, so as to be highest in the middle, and those edges which are placed together being sloped a little, so as to form rather less than a right angle with their respec- tive upper surfaces, they are, by an adequate weight, at once compressed and levelled. The fourth board of the last series becomes the first of the next, and the operation, which is called folding the boards, is repeated till the floor is finished. The nails are driven in a little below the surface of these boards, and the cavity is filled with glazier's putty. But in rooms not intended to be carpeted, and yet where a meat and clean appearance is indispensable, the use of putty must be avoided, and the mails must not be driven in from the top This object is obtained by dowelling the joints, that is, driving wooden pins into them in the middle of their thickness, and parallel to the surface, in the same manner as the coopers joint the boards forming the ends of their casks. In this case, one half of each pin entering the edges placed together, the boards, if the dowels be sufficiently numerous and properly placed, cannot rise or sink but in conjunction. The best place for the dowels is in the middle of the space between the joists. In the I best dowelled work, the nails are concealed when the floor is H o U # ou 483 DICTIONARY OF MECHANIGAL scIENCE. finished, for they are driven in slantwise through, the outer | edge only of each board. . Sometimes the joints of flooring | boards are rabbeted, that they may lap over each other a little way, and sometimes toothed into each other, or, as it is tech- | nically expressed, ploughed and tongued. When either of | these methods is adopted, the boards are not separated on their contraction, so as to leave an aperture between each pair, through which any thing can drop; but, such floors are more costly than others, not only on account of the extra labour, but the greater quantity of wood which they require. - It is always desirable to cover a floor, with boards in one length; but when it cannot be done, the ends of the two boards should invariably be upon a joist, and two of them should never be together in the same line. Yellow deal, well seasoned, is one of the best woods that can be selected for floors: the white sort, by frequent wash- ing, becomes blackish and disagréeable in its appearance. In the habitations of the labouring classes of society, the ground floors are often made of a kind of mortar. The best materials for this purpose are two-thirds of lime, one of coal- | ashes, and a small portion of clay. These ingredients are to be. well tempered with water, left to subside for a week or ten days, and then well worked up again. This operation should be repeated in the course of three or four days, till the mixture. becomes smooth and glutinous, when it is fit for use. It is to be aid on to the depth of two and a half or three inches, and carefully smoothed with a trowel. The hottest season of the year is the most proper for applying this composition, which, when completely dried, will make a most durable floor. XVIII. Proportions of Timbers, &c.—In the treatise entitled the “British Carpenter,” already referred to, are given the following Tables to shew the proportions of timbers for small and large buildings. . - - Proportions of Timbers for Small Buildings. Bearing Posts of Fir. Bearing Posts of Oak k-ºn Height Scantling Height Scantling if 8 feet 4 inc. square if 10 feet 6 inc. square T0 - 5 - 12 - 8 . 12 6 14 10 Girders of Fir. Girders of Oak. Bearing Scantling Bearing Scantling if 16 feet 8 in. by 11 if 16 feet 10 inc. by 13 20 10 12}| 20 12 14 24 12 14 || 24 14 15 Joists of Fir. Joists of Oak. Bearing Scantling Bearing Scantling if 6 feet 5 inc. by 2% if 6 feet 5 inc. by 3 9 6# 2% 9 7} 3 12 8 2} 12 10 3 Bridgings of Fir. Bridgings of Oak. Bearing Scantling Bearing Scantling if 6 feet 4 inc. by 2% if 6 feet 4 inc. by 3 8 . 5 2} 8 5% - 3 10 6 3 10 7 3 Small Rafters of Fir. Small Rafters of 6ak. ... Bearing Scantling Bearing Scantling if 8 feet | 3% inc. by 2%| if 8 feet | 4% inc. by 3 10 - 4} 2 10 5} : 12 | 5} 2}| 12 6} 3 Beams of Fir, or Ties. Beams of Oak, or Ties. ... Length Scantling Length Scantling if 30 feet 6 inc. by 7 if 30 feet 7 inc by 8 45 9 8% 45 [() 11; 60 12 11 60 13 15 Principal Rafters of Fir. Principal Rafters of Oak. - Scantling Scantling Length Top Bottom | Length Top Bottom if 24 feet|5 ins. & 6| 6 ins. & 7 if 24 feet. 7 ins. & 8, 8ins. & 9 36 |6% 8| 8 10| 36 ||8 9| 9 |0}|. 48 8 10|10 12| 48 19 10| 10 12 Proportions of Timbers for Large Buildings. Bearing Posts of Fir. Bearing Posts of Oak, Height Scantling Height Scantling if 8 feet 5 inc. square if 8 feet 8 inc. square 12 8 - 12 | 12. , 16 10 16 16 Girders of Fir. - Girders of Oak. . Bearing Scantling Bearing Scantling if 16 feet 9% inc. by 13 if 16 feet 12 inc. by 14 20 12 14 20 15 15 24 13} 15 , 24 I8 16 Joists of Fir. ... Joists of Oak. . . . Bearing Scantling Bearing Scantling if 6 feet 5 inc. by 3 if 6 feet 6 inc. by 3 9 7% 3 9 9 3 12 10 3 12 12 3 Bridgings of Fir. Bridgings of Oak. Bearing Scantling Bearing Scantling if 6 feet 4 inc. by 3 if 6 feet 5 inc. by 3A 8. 5% 3 8 j 6% 3% 10 7 3 10 8 3} Small Rafters of Fir. Small Rafters of Oak. Bearing Scantling Bearing cantling if 8 feet 4% inc. by 3 if 8 feet 5% inc. by. 3 10 5% 3 || 10 7. 3 T2 . 6} 3 12 | 9 3 Beams of Fir, or T'ies. Beams of Oak, or Ties. Length Scantling Length Scantling if 30 feet 7 inc. by 8. if 30 feet 8, inc. by 9 45 10 11}| 45 11 12 60 13 15 GO i 14 16 Principal Rafters of Fir. Principal Rafters of Oak. Scantling - Scantling Length Top Bottom | Length Top Bottom if 24 feet|7 ins. & 9) 8 ins. & 9. if 24 feet|8ins, & 9| 9 ins. & 10 36 8 9| 9 10%| 36 9 10|10 12 48 9 : 10| 10 12 48 10 13||12 14 The author of the preceding, tables observes, that though they seem so plain as not to require explanation, yet a few re- marks might be subjoined with propriety. All binding or strong joists, he then adds, ought to be half as thick again as common joists; that is, if a commnn joist be given three inches thick, a binding joist should be four inches and a half thick, although of the same depth. If it be not convenient to allow the posts in partitions to be square, which is the best form, in such cases, multiply the square of the side of the posts, as here given, by itself: for ins stance, if it be six inches square, then as six times six is thirty- six, to keep this post nearly to the same strength, find two numbers producing the same amount; as suppose the partition to be four inches thick, then let the post be nine inches the other way, so that nine times four being thirty-six, the area of its horizontal section is the same, and its strength nearly equal to the square post. Posts that go to the height of two or three stories, need not hold the proportions given in the table, because at every floor they meet with a tie. Admit a post to be thirty feet high, and that in this height there are three stories, two of ten feet and one of eight feet: look for posts of fir ten feet high, their scant- ling is five inches square, that is, twenty-five square inches, which double for the two stories; and also take that of eigh' feet high, being four inches, that is, sixteen inches square, all which being added together, make sixty-six inches ; so that such a post would be rather more than eight inches square. . On occasion it may be lessened in each story as it rises. All beams, ties, and principal rafters, ought to be out or forced in framing to a camber, or roundness, on the upper side, and the convexity may be about one inch in eighteen or twenty feet. The reason is, that all timber, partly from its own weight, but | principally from the weight of the covering or other burden it 484 H O U Ho U DICTIONARY of MECHANICAL scIENCE. has to bear, will swag; and unless prepared in this manner, that it may never become concave, a degree of unsightliness, and often of inconvenience, will be produced. The joists in floors, the purlines, (or timbers into which the small rafters are tenoned in roofs,) &c. should not exceed twelve feet in the length of their bearing, or from support to support. The strong joists of floors should not be at a greater distance than five feet, nor common joists more than ten or twelve inches apart. t •: * According to the experiments of Muschenbroek, fir is able to bear compression in the direction of the length of its fibres, or to sustain as a post, a much greater weight than oak, but is far inferior to oak when the weight is suspended. In the pre- ceding tables, therefore, the scantlings of fir bearing posts and principal rafters are properly made less than those of oak ; but for other timbers, particularly for ties, many are of opinion that the proportions of the author's tables should be reversed, and the scantling which he has assigned to fir should be given to oak. * - - XIX. BUILDING ACT,--All the buildings erected in London and the several parishes within the bills of mortality, are sub- jected to the regulations of an act of parliament, of the 14 Geo. III, the main object of which is to lessen the danger to be apprehended from fire. As many of the provisions of this act arc of great importance, and deserve to be universally known and acted upon, we shall conclude the subject of Building by an abstract of them. Those which relate to the Carpenter are the following: . tº * * Timber partitions between building and building, erected or erecting before the passing of the act, may remain till one of the adjoining houses is rebuilt, or till one of the fronts, or two- thirds of the fronts which abut on such timber partition, is taken down to the bressummer, or one pair of stairs floor, and rebuilt. Three months’ notice of the pulling down of such wooden partition, when decayed or of insufficient thickness, to be given by the proprietor to the owner or occupier of such a house, and if the house be empty, such notice to be stuck up on the front or front door of it. Af No timber hereafter to be laid in any party arch, or party wall, except for bond to the same ; nor any bond timber within nine inches of the opening of a chimney, nor within five inches of the flue; nor any timber within two feet of any oven, stove, copper, still, boiler, or furnace. -. . The wood work of chimney breasts to be fastened to the said breast with iron wall hooks, spikes, nails, or holdfasts, which must not be driven more than three inches into the wall, or nearer than four inches to the inside of the opening of the chimney. - No timber bearer to wooden stairs let into an old party wall, must come nearer than eight inches and a half to the flue, nor nearer than four inches to the internal finishing of the adjoin- ing building. g No timber to be laid under any hearth to a chimney, nearer than eighteen inches to the upper surface of such hearth. No timber must be laid nearer than eighteen inches to any door of communication through the party walls of warehouses and stables. Bressummers, story posts, and plates thereto, are only per- mitted in the ground story, and may stand even with the out- side of the wall, but must go no deeper than two inches into a party wall, nor nearer than seven inches to the centre of a party wall, when it is two bricks thick, nor nearer than four inches and a half, provided the party wall does not exceed one brick and a half in thickness. Every corner story post must be of oak, and at least twelve inches square, when employed for the support of two fronts. Window frames and door frames to the first, second, third, and fourth rate classes, are to be recessed in reveals, four inches at least. - - Boor-cases and doors to warehouses only of the first, second, third, or fourth rate classes, may be even with the outward face of the wall. No external decoration to be of wood, except cornices or dressings to shop windows; frontispieces to door-ways of the second, third, and fourth rate classes, and covered ways or por- j ticoes to buildings; but not to project beyond the original line of the house in any street or way. Such covered way or por- tico not to be covered with wood; nor such cornice, covered way, or roof of the portico, to be higher than the under side of the sill to the windows of the one pair of stairs floor. No flat gutter or roof, nor any turret, dormer, or lantern light, or other erection placed on the flat of the roof belonging to the first, second, third, fourth, and fifth rate classes, to be of wood. No wooden water tanks must be higher from the ground than the tops of the windows of the ground story. - Those provisions of the act which relate to the Bricklayer are the most numerous. Every master bricklayer must give twenty-four hours’ notice to the surveyor of the district, con- cerning the building to be altered or erected; but if the build- ing is to be piled or planked, or begun with wood, it becomes the business of the carpenter to give such notice. - The footings of the walls are to have equal projections on each side; but where any adjoining building will not admit of such projections to be made on the side adjoining to such building, this direction to be complied with as nearly as possible. -- The timbers in each rate, as girders, beams, trimming joists, &c. may have as much bearing as the nature of the wall will admit, provided four inches be left between the ends of such timber and the external surface of the wall. - XX. Eacternal Walls.-Every front, side, or end wall, not being a party wall, is called an external wall. External walls, and other external enclosures to the first, second, third, fourth, and fifth rates of buildings, must be of brick, stone, artificial stone, lead, copper, tin, slate, tile, or iron; or of some or all of these materials in conjunction, ex- cept the planking, piling, &c. for the foundation, which may be of wood. If any part to an external wall of the first and second rate is built wholly of stone, it is not to be less in thickness than as follows: first rate, fourteen inches below the ground floor, nine inches above the ground £oor; second rate, nine inches above the ground floor. - - *. Where a recess is meant to be made in an external wall, it must be arched over, in such a manner, that the arch and the back of such recess shall respectively be of the thickness of one brick in length ; hence no walls are allowed to be recessed which are not more than one brick in thickness. - - No external wall to the first, second, third, and fourth rate, is ever to become a party-wall, unless the same shall be of the height and thickness above the footing, as is required for each party-wall to its respective rate. - XXI. Party-Walls.—Buildings of the first, second, third, and fourth rate, which are not yet designed by the owner thereof to have separate and distinct side walls, on such parts as may be contiguous to other buildings, must have party- walls; and they are to be placed half and half on the ground of each owner, or of each building respectively. and may be built thereon, without any notice being given to the owner of . the other part, the first builder having a right so to do, when building against vacant ground. * * Party-walls, chimneys, and chimney shafts hereafter to be built, must be of good sound brick or stone, or of sound bricks and stone together, and must be coped with stone, tile, or brick. Party-walls, or additions thereto, must be carried up thirteen inches above the roof, measuring at right angles with the back of the rafter, and twelve inches above the gutter of the highest building which gables against it; but where the height of a party-wall so carried up, exceeds the height of the blocking course or parapet, it may be made less than one foot above the gutter, for the distance of two feet six inches from the front of the blocking course or parapet. w Where dormers (the term for windows in roofs, differing from sky-lights by their being vertical) or other erections are fixed in any flat or roof, within four feet of any party-wall, such party-wall is to be carried up against such dormer, and must extend at least two feet wider, and to the full height of every such dormer or erection. - No recess is to be hereafter made in any party-wall of the first, second, third, and fourth rate, except for chimney flues, H O U H O U 485 DICTIONARY OF MECHANICAL SCIENCE. girders, &c. and for the ends of walls or piers, so as to reduce such wall in any part of it to a less thickness than is required by the act, for the highest rate of building to which such wall belongs. - No opening is to be made in any party-wall, except for com- munication from one stack of warehouses to another, and from one stable building to another, and the communications al- lowed must have wrought iron doors, and the pannels thereof are not to be less than a quarter of an inch thick, and must be fixed in stone door-cases and sills. But there may be open- ings for passages or ways on the ground, for foot passengers, cattle, or carriages, which must be arched over throughout with brick or stone, or brick and stone together, of the thigk- ness of a brick and a half at the least, to the first and second rate, and one brick to the third and fourth rate. And if there is any cellar or vacuity under such passage, it is to be arched over throughout in the same manner as the passage over it. No party-wall, or party-arch, or shaft of any chimney, new or old, must be cut into, except for the following purposes: if the fronts of buildings are in a line with each other, a recess may be cut, both in the fore and back front of such buildings, (as may be already erected,) for the purpose of inserting the end of such other external wall, which is to adjoin thereto. This recess must not be more than nine inches deep from the outward faces of such external walls, and not be cut beyond the centre of the party-wall. And for the purpose of inserting bressummers and story-posts, that are to be fixed on the ground floor, either in the front or back wall, the recess may be cut from the foundation of such new wall to the top of such bres- summer, fourteen inches deep from the outward face of such wall, and four inches wide in the cellar story, and two inches wide on the ground story. The same may also be done for the purpose of tailing-in stone steps, or stone landings, as for bearers to wood stairs, or for laying-in stone corbels for the support of chimney jambs, girders, beams, purlines, binding or trimming joists, or other principal timbers. Perpendicular recesses may also be cut in any party-wall, whose thickness is not less than thirteen inches, for the pur- pose of inserting walls and piers therein; but they must not be wider than fifteen inches, or more than four inches deep; and no such recess is to be nearer than ten feet to any other recess. All such cuttings or recesses must be immediately made good, and effectually pinned up, with brick, stone, slate, tile, shell, or iron, bedded in mortar. No party wall must be cut for any of the above purposes, if the same will injure, displace, or endanger the timbers, chim- neys, flues, or internal finishings of the adjoining buildings. The footing may be cut off on the side of any party-wall, where an independent side wall is intended to be built against such party-wall. When any buildings (inns of court excepted) that are erected over gate-ways, or public passages, or have different rooms and floors, the property of different owners, are to be rebuilt, they must have a party-wall, with a party-arch or arches of the thickness of a brick and a half at thes least, to the first and second rate, and of one brick to the third and fourth rate, be- tween building and building, or between the different rooms and floors that are the property of different owners. Inns of court are required only to have party-walls where any room or chamber communicates to each separate and dis- tinct staircase, and which are also subject to the same regula- tions as respect other party-walls. If buildings of different rates adjoin each other, and any ad- dition is intended to be made to the lower rate, the party-wall of such building must be such as is required for that of the higher rate adjoining. \ When any party-wall is raised, it is to be made of the same thickness as the wall in the story next below the roof of the highest building adjoining, but it must not be raised at all, unless it can be done with safety to such wall, and the build- ing adjoining thereto. Every dwelling-house built four stories high from the foun- dation, exclusive of rooms in the roof, must have its party-wall built according to the third rate, although such dwelling-house may be of the fourth rate. Every dwelling-house, also, ex- ceeding four stories in height from the foundations, exclusive of the rooms in the roof, must have its party-wall built accord- ing to the first rate, although such house may not be of the first rate. . - XXII. Chimneys.-No chimney is to be erected on timber, except on the piling, planking, &c. of the foundations of the building. Chimneys may be built back to back in party-walls; but when this is done, they must not be less in thickness from the centre of such party-wall than as follows: first rate, or adjoin- ing thereto, must be one brick thick in the cellar story, and half a brick in all the upper stories. Second, third, and fourth, rate, or adjoining thereto, must be three-quarters of a brick in the cellar story; and half a brick in all the upper stories. Such chimneys in party-walls of any of the four rates, as do not stand back to back, may be built as follows; from the external face of the party-wall to the inward face of the back of the chimney in the cellar story, one brick and a half thick, and in the upper stories, one brick thick from the hearth to twelve inches above the mantle. If such chimney is built against any other wall, the back may behalf a brick thinner than above stated. Those backs of chimneys which are not in party-walls of the second, third, and fourth rate, must be in every story one brick thick at least, from the hearth to twelve inches above the mantle. These backs may also be half a brick thinner, if such chimney be built against any other wall. The breasts of chimneys, whether in party-walls or not, are not to be less than one brick thick in the cellar story, and half a brick thick in every other story. All partitions between flues must not be less than half a brick thick. Flues may be built opposite to each other in party walls, but they must not approach nearer to the centre of such wall than two inches. All chimney breasts next to the rooms, and chimney backs, and all flues, are to be rendered or pargeted. Backs of chimneys, and ſlues in party-walls against vacant ground, must be lime whited, or marked in some durable man- ner, but must be rendered or pargeted as soon as any other building is erected to adjoin them. - No timber must be over the opening of any chimney for sup- porting the breast; but all chimneys must have a brick or stone arch, or iron bar or bars. All chimneys must have slabs or foot paces of stone, marble. tile, or iron, at least eighteen inches broad, and at least one foot longer than the opening of the chimney when finished ; and such slabs or foot paces must be laid on brick or stone trimmers at least eighteen inches broad from the face of the chimney breast, except there be no room or vacuity beneath, in which case they may be bedded on the ground. Brick, funnels must not be made on the outside of the first, second, third, or fourth rate, next to any street, square, court, road, or way, so as to extend beyond the general line of the building in such situations. No metallic funnel or other pipe, for conveying smoke or steam, is allowed to be fixed near any public street, square, court, or way to the first, second, third, or fourth rate, and no such pipe is to be fixed on the inside of any building nearer than fourteen inches to any timber, or other combustible material. House. Every man’s house is as his castle, as well to defend him against injuries, as for his repose. Upon recovery in any real action or ejectment, the sheriff may break the house and deliver seisin, &c. to the plaintiff. Where the king is party, the sheriff may break the party’s house to take him, or to execute other process of the king; but he ought first to signify the cause of his coming, and request the door to be opened; when the door is open, the sheriff may enter and make execution at the suit of any subject; but where the door is shut, there he cannot break it to execute process at the suit of a subject. Though a house is a castle for the owner him- self and his family and his own goods, &c. yet it is no protec- tion for a stranger ſlying thither; or the goods of such a one to prevent lawful executions, nor for persons guilty of high trea- son, or breaches of the peace. A man ought so to use his house as not to damnify his neighbours. 6 H 486 H U N HI 'tj :N DrcTIONARY of MechANICAL scIENCE. HOUSED, at sea, expresses the situation of the great guns upon the middle and lower decks when they are run in, and the breech being let down, the muzzle rests against the side above the port: they are then secured by their tackles, muz- zle lashes, and breechings. . . - HOVERING, in Law. Ships of fifty tons, laden with cus- tomable or prohibited goods, hovering on the coasts of this kingdom, within the limits of any port (and not proceeding from foreign parts) must take a security in such sum of money to the amount of treble the value of such foreign goods then on board, that such ship shall proceed, as soon as wind and wea- ther, and the condition of the ship, will permit, on her voyage to ‘foreign parts. HUE and CRY, is the ancient common law process after felons, and such as have dangerously wounded any pèrson, or assaulted any one with intent to rob him. For the levying of hue and cry, although it is a good course to have a justice's warrant, where time will permit, in order to prevent causeless hue and cry; yet it is not necessary, nor always convenient; for the felon may escape before the warrant be obtained. HUER, or Hver, the Icelandic name for streams of heated water, which are forced with great violence through apertures in the earth, by internal causes, to a great height, in that island. • - HUGUENOTS, a term of contempt, first given to the French protestants, in the year 1560. This term probably owes its origin to an erroneous pronunciation of the German word Eid- genossen, which signifies sºvorn-fellows. name of that part of the Genevans who entered into an alliance with the Swiss cantons, in order to maintain their liberties against the Duke of Savoy. The name is also said to have been derived from a gate of the city in which they first assembled, HUMANITIES, in the and poetry, known by the name of literae kwmaniores. HUMIDITY. See HYGroMeter. - HUMULUS, in Botany, a genus of the dioecia pentandria. class and order. There is but one species, viz. H. lupulus, Hops, which see. HÚNDRED, a number equal to 10 times 10, denoted by the - Roman letter C, and written thus, 100. Hundred weight, a measure of weight equal to 112 lbs. and commonly denoted by the contraction cut. - - HUNDRED. Hundreds are not answerable to persons robbed, travelling on a Sunday: but are liable to penalty on expor- tation of wool : to damages sustained by pulling down build- ings, killing cattle, cutting down trees, burning houses, &c., plural, signify grammar, rhetoric, This had been the . destroying turnpikes or works on navigable rivers; cutting hop-binds, destroying corn to prevent exportation, and by wounding officers of the customs. All moneys recovered against the hundred to be levied by a rate. HUNGARIAN MACHINE, an hydraulic engine, is a very inge- nious application of the Hero Jet d’Eau principle. The following engraving represents this machine. A is the source of water elevated 136 feet above the mouth of the pit, and from this source there descends a pipe D of 4 inches diameter, which enters the crown of a copper cistern B, 8; feet high, 5 feet diameter, and 2 inches thick. The pipe D reaches to within 4 inches of the bottom of this copper cistern ; it has a cock at I. This cistern has a cock at Q, and a very large one at N ; from its top proceeds a pipe V EC two inches diameter, which goes down the pit 96 feet, and is inserted into the top of another brass or copper cistern C, 64 feet high, 4 feet diameter, and 2 inches thick; the latter containing nearly 83 cubic feet, which is about half the capacity of the former, viz. 170 cubic feet. Another pipe, FO, 4 inches diameter, rises from within 4 inches of the bottom of this lower cistern, is soldered into its top, and rises to the trough Z, which carries off the water from the mouth of the pit. This lower cistern communicates at the bottom with the water O, which collects in the drains of the mines. A large cock P serves to exclude or admit this water; another cock M, at the top of this cistern, communicates with the external air. - - - Now, suppose the cock I shut, and all the rest open; the upper cistern will contain air, and the lower cistern will be filled with water, because it is sunk so deep that its top is densed air from the lower cistern. below the usual surface of the mine-waters, Shut the cocks Q, N, M, P, and open the cock I. The water of the source A must run in by the urifice J, and rise in the up- - per cistern, compressing - H. A. the air above it, and ſº along the pipe VEC \ º - and thus acting on the surface of the water in the lower cistern. It will therefore, cause it to rise gradually in the pipe QF, where it will always be of such a height that its weight balances the elasticity of the coin- pressed air. Suppose no issue given to the air from the upper cistern, it would be compressed into one-fifth of its bulk by the column of 136 feet high ; for a column of 34 feet nearly ba- lances the ordinary elas- ticity of the air. There- fore, when there is an issue given to it through the -pipe V E C, it will drive the compressed air along this pipe, and it will expel water from the lower cistern. When the upper cistern is full of water, there will be 34 cubic feet of water expelled from the lower cistern. If the pipe O P had been more than 136 feet long, the water would have risenlä6 feet, being then in equilibrio with the water in the feeding pipe D, by the intervention of the elas- tic air; but no more water would have been expelled from the lower cistern than what fills this pipe. But the pipe being only 96 feet high, the water will be thrown out at Z with a considerable velocity. If it were not for the great obstruc- tions which water and air must meet with in their passage along pipes, it would issue at Z with a velocity of more than fifty feet per second. It issues however much more slowly, ### º Gł S; 3? ==}ls. --- * and at last the upper cistern is full of water, and the water would enter the pipe V E and enter the lower cistern, and, without displacing the air in it, would rise through the dis- charging pipe O P, and run off to waste. To prevent this, there hangs in the pipe V E a cork ball or double come, by a brass wire which is guided by holes in two cross-pieces in that pipe. When the upper cistern is filled with water, this cork plugs up the orifice V, and no water is wasted; the influx at J now stops. But the lower cistern contains compressed air, which would balance water in a discharging pipe 136 feet high, whereas OP is only 96. Therefore the water will continue to flow at Z till the air has so far expanded as to balance only 96 feet of water, that is, till it occupies one-half of its ordinary bulk, that is, one-fourth of the capacity of the upper cistern, or 42} cubic feet. Therefore 42 cubic feet will be expelled, and the efflux at Z will cease; and the lower cistern is about one- half full of water. When the attending workman observes this, he shuts the cock I. He might have done this before, had he known the orifice V was stopped; but no loss ensues from the delay. At the same time the attendant opens the cock N the water issues with great violence, being pressed by the con- - It therefore issues with the H U N H U N piction ARY of MECHANICAL scIENCE. 487 sum of its own weight and of this compression. These gra- dually decrease together, by the efflux of the water and the expansion of the air; but this efflux stops before all the water has flowed out; for there are 423 feet of the lower cistern * occupied by air. This quantity of water remains, therefore, in the upper cistern nearly : the workman knows this, because the discharged water is received first of all into a vessel con- taining three-fourths of the capacity of the upper cistern. Whenever this is filled, the attendant opens the cock P by a long rod which goes down the shaft; this allows the water of the mine to fill the lower cistern, and the air to get into the upper cistern, which permits the remaining water to run out of it. Thus every thing is brought into its first condition; and when the attendant sees no more water come out at N, he shuts the cocks N and M, and opens the cock I, and the opera- tion is repeated. - . . There is a very surprising appearance in the working of this engine. When the efflux at Z has stopped, if the cock Q be opened, the water and air rush out together with prodigious violence, and the drops of water are changed into hail or lumps of ice. It is a sight usually shewn to strangers, who are desired to hold their hats to receive the blasts of air: the ice comes out with such violence as frequently to pierce the hat like a pistol bullet. This rapid congelation is a remarkable instance of the general fact, that air by suddenly expanding generates cold, its capacity for heat being increased. - Now, from the above account of the procedure in working this engine, we see that the efflux both at Z and N becomes very slow near the end. It is found convenient therefore not to wait for the complete discharges, but to turn the cocks when about 30 cubic feet of water have been discharged at Z; more work is done in this way. A gentleman of great accuracy and knowledge of these subjects took the trouble of noticing parti- cularly the performance of the machine. He observed, that each stroke took up about three minutes and one-eighth ; and that 32 cubic feet of water were discharged at Z, and 66 were expended at N. The expense therefore is 66 feet of water falling 136 feet, and the performance is 32 raised 96, and they are in the proportion of 66 × 136 to 32 x 96, or of 1 to 0.3422, or nearly as 3 to 1. This, says Dr. Gregory, is superior to the performance of the most perfect undershot mill, even when all friction and irregular obstructions are neglected; and is not much inferior to any overshot pump-mill that has yet been erected. When we reflect on the great obstructions which water meets with in its passage through long pipes, we may be assured, that by doubling the size of the feeder and discharger, the performance of the machine will be greatly improved ; we do not hesitate to say, that it would be increased one-third : it is true that it will expend more water; but this will not be nearly in the same proportion, for most of the deficiency of the machine arises from the needless velocity of the first efflux at Z. The discharging pipe ought to be 110 feet high, and not give sensibly less water. Then it must be considered how inferior in original expense this simple machine must be to a mill of any kind which would raise 10 cubic feet 96 feet high in a minute, and how small the repairs on it need be, when com- pared with a mill. And, lastly, let it be noticed that such a machine can be used where no mill whatever can be put in motion. A small stream of water, which would not move any kind of wheel, will here raise one-third of its own quantity to the same height; working as fast as it is supplied. For these reasons, we join in opinion with Dr. Gregory, that the Hungarian machine eminently deserves the attention of the mathematicians and engineers, to bring it to its utmost perfec- tion, and into general use. There are situations where this kind of machine may be very useful. Thus, where the tide rises 17 feet, it may be used for compressing air to seven- eights of its bulk ; and a pipe leading from a very large vessel inverted in it may be used for raising the water from a vessel of one-eighth of its capacity 17 feet high ; or if this vessel has only one-tenth of the capacity of the large one set in the tide- way, two pipes may be led from it; one into the small vessel, and the other into an equal vessel 16 feet higher, which receives the water from the first. Thus one-sixteenth of the water may be raised 34 feet, and a smaller quantity to a still greater height; and this with a kind of power that can hardly be applied any other way, Máchines of this kind should not be forgotten, because opportunities may offer of making them highly beneficial, where other circumstances might dictate their erection. - • - Mr. J. W. Boswell has devised an apparatus, which when attached to such a machine as that at Chemnitz, enables it to work itself without attendance. See the foregoing figure. . A, is the reservoir, or upper level of water. - B, a chamber or cistern made of sufficient strength to bear the internal pressure of a column of water the height of A above it, multiplied by its own base. C, a chamber of the same strength as B, but of a smaller size; it is placed at the bottom of the pit from which the water is to be raised, and under the level of the water. These chambers would be stronger with the same materials, if of a globular or cylindrical form ; but the square shape is used in the drawing, merely for the facility of representing the position of the parts. - D, a pipe from the reservoir A, which passes through the top of B, and ends near its bottom, to convey water from A to B. , E, a pipe from the top of B to the top of C, to convey air from B to C. - * F, a pipe from the bottom of C to the level of the ground at the top of the pit, to carry off the water from the pit. G, a pipe from the bottom of B to carry off the water from it. H, a vessel to contain the water used in working the cocks; it is only placed on the top of B to save the construction of a stand on purpose for it. . I, a cock, or moveable valve (worked by the lever there represented) in the large pipe D. N, a stop-cock in the small pipe which conveys water from D to H. Its use is to make the engine work faster or slower, by letting water more or less quick into H; or to stop it alto- gether from working when required. - L, a moveable valve or cock in the small pipe L K. The lever which works it is connected by a strong wire with the lever which works I, and is balanced by a weight at its opposite extremity, sufficient to open both these cocks and shut N, when not prevented by a counter-weight. - N, a cock in the pipe G to open and shut it as wanted. ' G, a self-moving valve in the pipe F, which permits the water to pass upwards, but prevents its return. P, a self-moving valve at the bottom of C, which permits the water to pass into C, but prevents any from passing out of it; it is furnished with a grating, to prevent dirt getting in. R, a vessel suspended from the levers of I and L, capable of containing a weight of water sufficient to shut them. S, a vessel suspended from the lever of N : it must contain water enough by its weight to open N : it is connected by a chain to R, to keep it down as long as N is open. T, a syphon passing from the bottom of H, near its upper edge, and down again to the mouth of R. V, a self-moving valve of a sufficient levity to rise, when the water in B comes up to it, and close the pipe E ;, into which no water would else pass from B. A ball-cock, such as is used in common water cisterns, would do here. X, a syphon from the bottom of R, rising within an inch of its top, and passing down again to the mouth of S. Y, a small pipe at the bottom of S : this may have a stop- cock to regulate it, which, when stopped, will also stop the engine. The mode of this engine's working is as follows: Suppose the vessels V, H, R, and S, empty of water, and the cocks K and Y open, and the vessel C full of water. The weight on the lever of L will then open the cocks L and I, on which the water from A will ſlow into B and H. As the water rises in B, it will force the air through E into C, which strongly pressing on the water in C, will force it up through the pipe F, till the water in B rises to the lever of V and closes it, at which time it will be full of water, (the quantity flowing in being so regulated by the cock K.) and the water will flow from it through the syphon T into the vessel R, which, as it fills, shuts the cocks I and L, and prevents any more water coming into B and H. When R is full, the water flows through its syphon X, which fills S, and by it opens N, which empties B of water, and keeps N open as long as there is any water in H. - - 488 H U R. H U s DICTIONARY OF MECHANICAL scIENCE. When H is empty, B will be so too, (being so regulated by the cock K) on which, in a moment or two, R. and S will also be empty; which will cause the cocks I and L to open, and all things will be again in the state first supposed, for a repetition of the operations described. . To stop the engine, the cocks at K and Y should be shut, while S is full of water. To set it working, they should be open; and this is all the attendance it will require. As no one but an engineer should attempt to construct such an engine as this, it was useless to represent the manner of connecting the pipes by flanches, or otherwise ; or the proper methods of fastening and closing the parts, which are all well known to such as have made this art their study. HUNGARY WATER, denominated from a queen of Hun- gary, is made by distilling in balneo, fresh-gathered flowers of rosemary, two pounds; rectified spirits of wine, two quarts. HURDLES, in Fortification, twigs of willows or osiers in- terwoven close together, sustained by long stakes, and usually laden with earth. See For TIFICATION. sº HuRDLEs, in Husbandry, frames of split timber, or of hazel rods wattled together, to make sheep-folds, &c. HURRICANE, a furious storm of wind, owing to a con- trariety of winds. See WIND and WHIRLwi ND. Hurricanes are frequent in the West Indies, where they make terrible ravages, by rooting up trees, destroying houses and shipping, and the like. Hurricanes happen either on the day of the full, change, or quarter of the moon. From the unusual red- mess of the sun, great stillness, and at the same time turbu- lence of the skies, swelling of the sea, the like happening at the change of the moon, the natives comclude there will be a hurricane next full moon; and if the same signs be observed on the full moon, they expect one next new moon. As the wind betwixt the tropics is generally easterly, and upon the sun's going back from the northern tropic, the Western winds pour down with violence upon those parts, the opposition of these contrary winds cannot fail to produce a hurricane. Hurricanes shift not through all the points of the compass, but begin always with a north wind, veer to the east, and them cease; and their shifting between these two points is so Sud- den and violent, that it is impossible for any ship to veer with it.—The importance of the barometer, as indicating the ap- proach of hurricanes, may be learned from the following cor- roborative remarks on the subject, which we extract from an interesting letter to the Editor of the South African Chronicle: “Every one at all acquainted with the mechanism of a baro- meter, is aware that its construction originated in a discovery, that the mean density of the atmosphere is capable of support- ing a column of mercury equal to about thirty inches in length; it follows, therefore, that every deviation from that height is the result of some change or other in the actual density or gravity of the atmosphere which supports it, the trifling effect excepted, which is produced by the attractive and cohesive qualities of the tube in which it is confined ; but, although it is clear that no alteration can take place in the quicksilver, which is not occasioned by a proportional change in the weight of the atmosphere, these changes depend upon such a variety of causes, and are frequently so minute as not to be perceptible, or accompanied by any visible alteration of the weather, which is the reason why small deviations in the barometer do not always indicate any change whatever in the latter. It is a well-established fact, that the barometer undergoes little or no variation throughout the region of the tropics, except when under the influence of an approaching hurricane, when it is equally notorious that it invariably falls rapidly and consider- ably, as it inevitably must do, if we consider the principle upon which the quicksilver is supported in the tube, and con- nect it with the probable cause of these storms, which are as much exceeded in violence, as the situations in which they are generated are at most other periods in mildness, by the more boisterous climates of Europe. Of the danger attending them, (says Colonel Wright,) I have acquired some degree of know- ledge from dear-bought experience, and of their approach we may at all times be warned by an infallible monitor, although I fear it is too often fatally slighted, through ignorance, perverse- ness, or prejudice; because that part of the ocean to which these remarks are confined is frequently sailed over without having to encounter a hurricane; and because, throughout such navigation, the barometer may remain almost stationary, it is too apt to be thought a useless appendage to a ship in those seas; but, so far is this from being a just conclusion, that, in my opinion, the circumstance of its not being affected by any other weather than such as is attended with imminent danger, is the strongest argument that can be adduced for its being particularly valuable in those regions. In high latitudes the experienced eye and judgment of the sailor prove a pretty correct substitute for a barometer; but the tropical hurricane, like the wolf in the fable, always comes on when least expected, so far as appearances are concerned, and therefore the baro- meter is the only guide to be safely confided in. My conclu- sion then is, after many years’ experience of the navigation of those seas, as well as from theory, that, whenever the baro- meter is observed to fall suddenly and considerably any where within the tropics, it may be considered indubitable, that as uncommon degree of rarefaction of that part of the atmo- sphere is in progress, and that it will inevitably be followed by a violent reaction. Not a moment, therefore, is to be lost in bringing the ship to wind, and preparing her for a storm ; from that moment the ship has passed the circumference of a circle, the centre of which is the centre of danger, inasmuch as it is the centre of the atmospheric expansion. I think I may fairly conclude, that the barometer will infallibly indicate the approach of a hurricane within the tropics, and that where the storm commences, there will it first subside, and there will it be most moderate: and if this be the truth, one would almost think it were an instrument placed by Providence in the hands of sailors to warm them of their danger; for if they are to pro- ceed in their course, in defiance of such warning, the baro- meter might as well be on shore. The sailor is an amphibious animal, and there being something peculiar in the disposition of animals which partake of a twofold nature, I recommend, in conclusion, that those gentlemen and ladies from the East, who have recourse to our salubrious climate for the purpose of repairing their shattered constitutions, should never, but when it cannot be avoided, engage a passage in a ship that is not possessed of one, and that they should keep guard over its silent salutary warnings themselves.” HUSBAND and WIFE, usually termed baron and feme, are one person in law; that is, the very being or legal existence of the woman is suspended during the marriage; or, at least, is incorporated and consolidated into that of the husband, under whose wing, protection, and cover she performs every thing; she is therefore called, in our law, (French,) a feme covert, that is, under the protection and influence of her husband, her baron, or lord ; and her condition, during her marriage, is called her coverture. A man cannot grant lands to his wife during the coverture, nor any estate or interest to her, nor enter into covenant with her; but he may, by his deed, cove- nant with others for her use, as for her jointure, or the like ; and he may give to her, by devise or will, because the devise or will does not take effect till after his death. All deeds executed by the wife, and acts done by her during her cover- ture, are void; except a fine, or the like matter of record, in which case she must be solely and secretly examined, that it may be known whether or not her act be voluntary. A wife is so much favoured, in respect of that power and authority which her husband has over her, that she shall not suffer any punish- ment for committing a bare theft, in company with or by coer- cion of her husband ; but if she commit a theft of her own voluntary act, or by the bare command of her husband, or be guilty of treason, murder, or robbery, in company with or by coercion of her husband, she is punishable as much as if she were sole; because of the odiousness and dangerous conse- quence of these crimes. By marriage, the husband hath power over his wife's person; and the courts of law still permit a husband to restrain a wife of her liberty, in case of any gross misbehaviour; but if he threaten to kill her, &c. she may make him find security of the peace, by suing a writ of supplicavit out of Chancery, or by preferring articles of the peace against him, in the court of King’s Bench, or she may apply to the spiritual court for a divorce, on account of cruelty. The husband, by marriage, obtains a freehold in right of his wife, if he takes a woman to wife that is seized of a freehold; and he may make H Y D H Y I DICTIONARY OF MECHAN1GAL sor ENCE. 489 a lease thereof for twenty-one years, or three lives, if it be made according to the statute 32 Henry VIII. c. 28. The husband also gains a chattel real, as a term for years, to dis- pose of, if he please, by grant or lease in her lifetime, or by surviving her: otherwise it remains with the wife; and upon execution for the husband's debt, the sheriff may sell the term during the life of the wife. The husband also, by the marriage, hath an absolute gift of all chattels personal, in possession of the wife in her own right, whether he survives her or not. But if these chattels personal arc choses in action, that is, things to be sued for by action, as debts by obligation, contract, or the like, the husband shall not have them, unless he and his wife recover them. . - - By custom in London, a wife may carry on a separate trade; and as such, is liable to the statutes of bankruptcy, with re. spect to the goods in such separate trade, with which the hus- band cannot intermeddle. If the wife be indebted before marriage, the husband is bound afterwards to pay the debt, living with the wife; for he has adopted her and her circum- stances together; but if the wife die, the husband shall not be charged for the debt of his wife after her death; if the creditor of the wife do not get judgment during the coverture. The husband is bound to provide his wife necessaries, and if she contract for them, he is obliged to pay for them ; but for any thing besides necessaries he is not chargeable: and also, if a wife elope, and live with another man, the husband is not chargeable even for necessaries; at least if the person who furnish them be sufficiently apprized of her elopement. A man having issue by his wife, born , alive, shall be tenant by courtesy of all the lands in fee-simple, or fee-tail general, of which she shall die seised ; and after her death, he shall have all chattels real ; as the term of the wife, or a lease for years of the wife, and all other chattels in possession; and also all such as are of a mixed nature, (partly in possession and partly in action,) as rents in arrear, incurred before the marriage or after; but things merely in éction, as ef a bond or obligation to the wife, he can only claim them as administrator to his wife, if he survive her. If the wife survive the husband, she shall have for her dower, the third part of all his freehold lands: so she shall have her term for years again, if he have not altered the property during his life: so also she shall have again all other chattels real and mixed; and so things in action, as debts, shall remain to her, if they were not received during the marriage: but if she elope from her husband, and go away ciled to her, and permitted her to cohabit with him.—Watkins's Cyclopædia. HUSBAND, Ship's, the owner, who takes the direction and management of a ship's concern upon himself, the other owners paying him a commission for his trouble. explains the means of making the earth produce, in plenty and perfection, those vegetables which are necessary to the sub- sistence of man, and of the animals reared by him for food or labour. To explain the various branches of this important article would require a volume, or an extended account which our pages cannot admit. To the agriculturist we would recom- mend Townes's Farmer's Directory, as a work replete with valuable information. * HUSTINGS, a court held before the Lord Mayor and Alder- men of London. Error on attaint lies there of a false verdict in the sheriff's court. - HUY GENS, a very celebrated Dutch mathematician and astronomer, who flourished in the 17th century. He has been chiefly distinguished for making improvements in the telescope, the air pumps, and pendulums. HYADNA, in Natural History, an animal remarkable for its untameable ferocity. It is chiefly an inhabitant of the most solitary regions of the torrid zone. the embryo plant from injuries during winter. HYDRA Polypes, in Natural History, a genus of the Modern philosophy has dignified this science by the name of vermes zoophyta class and order; an animal fixing itself by the base, linear, gelatinous, naked, contractile, and furnished with setaceous feeders; inhabiting fresh waters, and producing its - | Centaurus; and east, by Lupus and Scorpio. HUSBANDRY, or AGRICULTURE, is the science which deciduous offspring or eggs from the sides. ' Thur, are five species. When a polype is cut transversely, or longitudinally, into two or three parts, each part in a short time becomes a perfect animal; and so great is this prolific power, that a new animal will be produced even from a small portion of the skin of the old one. If the young ones be mutilated while they grow upon the parent, the parts so cut off will be reproduced; and the same property belongs to the parent. A truncated portion will send forth young ones before it has acquired a new head and tail of its own, and sometimes the head of the young one supplies the place of that which should have grown out of the old one. If we slit a polype longitudinally through the head to the middle of the body, we shall have one formed with two heads; and by again slitting these in the same manner, we may form one with as many heads as we please. A still more Surprisin; property of these animals is, that they may be grafted together. If the truncated portions of a polype be placed end to end, and gently pushed together, they will unite into a single one. The two portions are first joined together by a slender neck, which gradually fills up and disappears, the food passing from one part into the other; and thus we may form polypes, not only from different portions of the same animal, but from those of different animals. We may fix the head of one to the body of the other, and the compound animal will grow, eat, and multiply, as if it had never been divided. By pushing the body of one into the mouth of another, so far that their heads may be brought into contact, and kept in that situation for some time, they will at last unite into one animal, only having double the usual number of arms. The hydra fusca may be turned inside out like a glove, at the same time that it continues to eat and live as before. The lining of the stomach now forms the outer skin, and the former epidermis constitutes the lining of the stomach. º HYDRA, the Female Snake, is an immense constellation of the Southern hemisphere, extending for above 100 degrees from the west to east, beneath the Crab, the Lion, and the Virgin. This constellation is said to represent the water ser- pent destroyed by Hercules. The origin of the Celestial Snake is as doubtful as that of the Crow or the Cup; for another fable tell us that Apollo, intending to offer a sacrifice to Jupi- ter, sent a crow with a cup for some water; but the bird having amused itself otherwise than it had been bidden, and returning | without its errand, excused itself to the god, by affirming that to the stream into which it wished to dip the cup was guarded by with her adulterer, she shall lose her dower; unless her hus- band had willingly, without coercion ecclesiastical, been recon- an enormous serpent. Apollo, to punish the falsehood of the crow, placed it opposite to the cup, and charged the serpent | not to allow it to drink. The boundaries and contents of this constellation are :- North by the zodiacal signs Cancer, Leo, and Virgo; west by Monoceros; south by Argo Navis, Antlia. Pneumatica, and There are sixty stars in this constellation, the chief of which is Alphard, (or Cor Hydrae,) of the 2d magnitude, three of the 3d, twelve of the 4th, &c. a Hydrae culminates at the following hours, in astronomical time, on the 1st of every month throughout the year: Merid. alt. 46° 21'45"/. - MONTH. CULM. MonTH. CULM. MonTH. CULM, ho. mi. see. ho. mi. sec. ho. mi. Sec. Jan. 14 30 4 May 6 45 26 Sept. 22 35 10 Feb. 12 18 16 June 4 43 5 Oct. 20 47 22 Mar. 10 20 35 || July 2 39 12 || Nov. 18 51 15 April 8 36 22 Aug. 0 34 39 Dec. 16 47 36 HYDRATE, in Chemistry, expresses the chemical union ot water with any substance, and especially with certain metallic oxides. - HYDRAULICON, Water Organ, in Music, an instrument acted upon by water; the invention of which is said to be of higher | antiquity than that of the wind organ. - HYBERNACULUM, that part of the plant which defends HYDRAULICS. The science of hydraulics teaches us the method of estimating the swiftness and force of fluids in motion, Hydrodynamics, or the application of Dynamics to the impul- sion and flow of water and other liquids, - * * . . tº The pressure of water against the sides of vessels is in- 6 I 490 H Y D H Y D DICTIONARY OF MECHANICAL SCIENCE. creased by an increase of depth: this holds true, of water in vessels, canals, rivers, reservoirs, &c. and the proportion is as the square of the depth, or altitude. Upon the principles of this science many machines worked by water are constructed; and several different engines used in the mechanical arts, various kinds of mills, pumps, and fountains, are but applica- tions of this theory judiciously applied. The velocity with which water spouts from a hole at the side, or in the bottom of a vessel, is as the square root of the depth or distance of the hole below the surface of the water; for in order to make double the quantity of a fluid run through one hole as through another of the same size, it will require four times the pressure of the other, and therefore the aperture must be four times the depth of the other below the surface of the water; and for the same reason, three times the quantity running in an equal time through the same son l of hole must run with three times the velocity, which will require nine times the pressure, and, consequently, the hole must be nine times as deep below the surface of the fluid, and so on. - As a proof of this, the following experiment can be tried :- Let two pipes of equal-sized bores be fixed into the side of a vessel, one pipe being four times as deep below the surface of the water in the vessel as the other is ; and while the pipes run, let water be poured constantly into the vessel so as to keep it always full. Then, if a cup that holds a pint be so placed as to receive the water that spouts from the upper pipe, and at the same moment a cup that holds a quart be placed to receive the water from the lower pipe, both cups will be filled at the same time by their respective pipes. To Construct a Water Measure.—When a stream of water flows into a cistern just as fast as it is discharged, the fluid must evidently maintain a constant level, from which the cele- rity is easily computed. Suppose the altitude 3 inches, the velocity of discharge would be 8 V4, or 4 feet each second ; i.e. 240 feet a minute. The delivery would, therefore, be a cubic foot a minute, if the aperture were only the 240th part of a square foot, or three-fifths of a square inch. This opening. corresponds to a circle whose diameter is '874 parts of an inch. Thus we have a standard measure for ascertaining readily the quantity of water delivered in a minute, &c. by any pipe or conduit. Let A B, in the annexed figure, be a cylinder of tin 4 feet long and 1 foot diameter, fitted with a float C, bearing a slen- der dividing rod, which passes thro' a hole in the tra- verse bar E stretch ed across the sum- mit of the cylin- der. This rod is marked 1, 2, 3, 4, at the distances of 3, 12, 27, and 48 inches, being the - fourth parts of the squares of the first numbers in feet. The divisions may likewise be quar- . tered, by begin- ning with the 16th part of 3, 12, 27, and 48 inches, and continuing thepro- cess by multiply- * ing the squares of 5, , &c. as far as 16 by 3, and dividing the products again by 16, The cylinder having a circular hole with a fine edge cut in the bottom, and poised at some dis- tance from the ground to receive the current F, the water mounts gradually in the vessel till it has gained an altitude sufficient to cause a discharge equal to the whole influx. The rod then indicates the number of cubic feet received every minute. But the application of this measurer may be extended, by adapting to it a series of apertures which screw into the bot- tom of the cylinder. Let them have successively these diame- ters in inches, 437—1874–1748—and 3:496. The rod would then be square, and marked on all its four sides; the divisions on the first side corresponding to a discharge of 3, #, #, and one cubic feet; those on the next to 1, 2, 3, 4; those on the third side to 4, 8, 12, and 16; and those on the fourth side intimating a flow of 16, 32, 48, and 64 cubic feet every minute. From these data, it is easy to construct other moduli suited to particular limits. The correction required in the size of the apertures, to accommodate theory with practice, will be after- wards explained. - A cistern from which the water trickled through a small perforation at the bottom, was employed by the ancients, under the name of a clepsydra or water-clock, to measure time. In a cylinder the flow would evidently diminish, as the level of the surface was incessantly lowered. To procure an uniform descent of the water, it would be necessary to adopt the figure of a conoid of the parabolic kind, each circular section of which is proportional to the square root of the corresponding altitude. Suppose this were 24 feet, and the diameter at the top 13:28 feet, the diameters of the successive sections being always six times the fourth root of the altitude. The velocity of efflux would then be 8 V 24 = 39.192 feet each second. If the water sank at the rate of a foot every hour, the width of the orifice would be to the extreme diameter, or 13:28, as 1 to 60 V 39'192. This gives an aperture of '424 parts of an inch. A conoid of such dimensions would, therefore, answer correctly as a clepsydra, the equable subsidence of a float marking the series of twenty-four hours in a natural day. This float being fastened to a thread wound about a cylindrical barrel, of a foot in circumference, would carry the index of a dial regularly round. - - - To shew the velocity with which water spouts out at a hole in. the side of a vessel, and the horizontal distance to which it is thrown. —The horizontal distance to which a fluid will spout from a horizontal pipe in any part of the side of an upright vessel below the surface of the fluid, is equal to twice the length of a perpendicular to the side of the vessel drawn from the mouth of the pipe to a semicircle described upon the altitude of the fluid ; and, therefore, the spout will be to the greatest distance possible from a pipe whose mouth is at the centre of the semi- circle; because a perpendicular to its diameter (supposed parallel to the side of the vessel) drawn from that point, is the longest that can possibly be drawn from any part of the diame- ter to the circumference of the semicircle. It is observed, that in every length of pipe, answering to 50 times its diameter, there is a waste of power equal to that which produces the general impulsion. With a very gentle slope, a pipe of 1:582 feet diameter, will give the flow of a single foot each second, and a pipe of one foot wide will dis- charge only 1.243 cubic fect of water in the same time. Let two pipes, as C and g, of equal sized bores, be fixed into the side of the vessel A B, as in the following figure, tº- C 4. | . 2 C * = e º sº. ‘.........2. sf: d Jº 2 a D : * M. K. †† t ::fiſſ; FrºW the pipeg being four times as deep below the surface of the water at b in the vessel, as the pipe C ; and whilst these pipes H Y D HI Y D 491 DICTIONARY OF MECHANICAL SCIENCE. run, let water be constantly poured into the vessel, to keep the surface still at the same height. Then, if a cup that holds a pint be so placed as to receive the water that spouts from the pipe C, and at the same moment a cup that holds a quart be SO placed as to receive the water that spouts from the pipe 9, both cups will be filled at the same time by their respective pipes. To illustrate the second division of this proposition, namely, that the fluid will spout to the greatest distance possible from a pipe whose mouth is at the centre of the semicircle, we have only to suppose the vessel A B (see the preceding figure) to be full of water, and the horizontal pipe D to be in the middle of its side, and the semicircle N e de b de- scribed upon D as a centre, with the radius or semidia- meter D N, or D b, the perpendicular D d to the diameter N D b is the longest that can be drawn from any part of the diameter to the circumference N e d c b. And if the vessel be kept full, the jet G will spout from the pipe D, to the horizontal distance N M which is double the length of the perpendicular D d. If two other pipes, as C and E, be fixed into the side of the vessel at equal distances above and below the pipe D, the perpendiculars, C c and Ee, from these pipes to the semicircle, will be equal; and the jets F and H spouting from them will each go to the horizontal distance NK ; which is double the length of either of the equal perpendiculars Ce or E e. It is very obvious, that when an aperture is made in the side of a vessel holding any fluid, the equilibrium of hydrostatic pressure is destroyed, and this force, which was exerted equally all round the inner surface, now ceases to act at the opening, or rather it expends its action there, in projecting the uncovered portion of the fluid. The reaction, or incessant recoil sustained by the general mass, will hence be the same as the external pressure of the column of the fluid of equal alti- tude directed against the sectipn of the orifice. If the vessel have therefore a cylindrical form, and turn freely about a ver- tical axis, while it carries under it two horizontal branches, extending both ways, each of them perforated near the end at right angles to their plane with the axis, but in opposite sides; the machine will be driven backwards by the spouting fluid, and forced to revolve as long as the action subsists. The forge thus exerted is equal to the weight of a column of the fluid having the general altitude, with the two apertures for its base, But the effect becomes augmented in this case by the length of -the arms or levers to which the power is applied. This prin- ciple has been long successfully adopted in the construction Of a very simple but efficient water-mill, commonly designated Barker's mill. It is capable, however, of various other useful and important applications, which remain still to be carried into execution. The transition from these principles to those on which some maritime phenomena depend, is at this place both natural and easy. We shall, therefore, in the next branch of this article proceed to illustrate the mechanical principle of Whirlpools:- Thus, if a cylindrical glass vessel, as in the figure, partly filled with water, be put on a whirling table, the central depression of the liquid will increase as the circum- volution is accelerated, while its sides will rise up. It will then divide at the bottom, and spread more upwards, forming always a parabolic conoid, but with a di- minishing parameter. If a thin ring were applied round the top of the cylinder, the water in its extreme celerity would cover the inside of the cylinder with a stratum of almost equal thickness, Suppose a cylinder A B, 6 inches wide and 16 inches high, filled - with water to the altitude of four inches: When the circumvolu- tion is performed in '68", the water is depressed an inch, the central part standing at 33 and the sides at 43 : but when the cylinder circulates in 24", the cavity sinks eight inches in the bottom, and rises at the sides to the height of 8 inches. If the revolution were achieved in “15”, the water would rise to the lips, leaving a dry circle at the bottom of the vessel of 249 inches in diameter. Hence, as we have said, the origin of dim- ples on the surface of small streams, and , of whirlpools in mighty rivers and narrow seas. The effect is produced by the lateral attrition of adverse currents, which extending their influence from the neutral point or centre of equal and opposite action, gradually convert their parallel motions into a com- bined system of circumvolution. Suppose each current had a velocity of 9 miles an hour, or 13.2 feet each second, and the radius of the whirlpool to be 100 feet; the time of cir- culation would then be 47.6", and the depression in the centre of the gulf only 2.72 feet, the parameter of the parabola being 3672 feet. When water issues through a simple circular aperture in a thin plate, it forms a contracted vein of a conical or rather tapering funnel shape, its section being reduced to very near five-eighth parts at a distance little more than half its diame- ter. If a tube of this figure be annexed, the quantity of dis- charge will come within the thirtieth part of the result of theory, as computed for the exterior aperture. But the adjutage being directed upwards, the jet will rise to fourteen-fifteenth parts of the whole height of the incumbent column. If to this tapered spout another conical tube five times longer, and opening to the original width, be joined, the dis- charge of water will be augmented from 21 to 38 parts. The effect of the adjutage is now the greatest possible, the absolute flow from the interior aperture being only 40 parts, according to theory. This pipe widens at an angle of about three degrees; but when the annexed piece diverges at a greater angle, its influence becomes diminished, and appears to cease altogether at an angle of sixteen degrees. The stream has now ceased to fill up the whole of the cavity, and is consequently no longer augmented by adhesion to the sides of the spout. The lateral action of water flowing through a pipe is evinced in a more striking manner. Let a cylinder one inch wide and three inches long be adapted to an orifice at the bottom of a cistern ; and on the upper side, at the distance of half an inch from its origin, let a narrow arched glass tube be inserted and carried down to a bason of water three feet lower. When the stream is projected with a velocity of nine feet in a second, it will draw up water to the height of two feet; but if the tube be shortened within that limit, the slender column will mix with the body of the current, and soon drain the contents of the bason. When a conical tube, opening with a considerable angle of divergence, is substituted, a series of slender glass tubes inserted at different distances from the interior aperture will be found to raise the water to several heights, which diminish as the stream begins to separate from the sides of the spout. This property of running water may, in various situations, be turned to useful account. By connecting the edge of the stream, for instance, by means of a small slanting pipe, with a collection of water at a lower level, this will be gradually drawn up and carried away in the general current. If a swift de- scending rivulet be made to shoot across any small pool, it will sweep the water over its opposite bank. Venturi, to whom we are chiefly indebted for these remarks, availed himself of the rapidity and lateral draught of a mill-race, to drain a marsh situate considerably below it, near the city of Modena. The same principle is likewise the principal cause of the action of the Hungarian blowing machine, which consists of a very tall perpendicular pipe, terminating below in a close wide box. A stream of water rushes down this shaft, drawing along with it the air which enters the small holes pierced along the sides, and becomes accumulated and condensed in the chamber, whence it again issues in a powerful blast on opening a cock. The blowing and dispersion of the spray on all sides from water-falls have a like origin. A body of air is involved in the broken descending current: collected in the recess or broken cavity, it exerts its elastic efforts in every direction. The adhesion of running water to the sides of its channel is also the main cause of those eddies which impede the general motion. If a ſluid suffers impediment while escaping at a small aper- ture, it encounters much greater obstruction in effecting its passage through a train of pipes, or flowing over an extended 492 H Y D 13 Y D .DICTIONARY OF MECHATNICAL SCIENCE. channel. This retardation, however, is quite distinct in its nature from ordinary friction. When a solid is drawn along the surface of another solid body, it is virtually made to ascend over a series of inclined planes, and consequently the impedi- ament it meets with may be viewed as merely equal to a cer- tain portion of its weight, independent of the rapidity or slowness of the motion. But a fluid, in its passage over a resisting surface, needs not have its whole mass either elevated or depressed. Those particles only which come in succession to touch the solid boundary, are impeded and detained. The pressure of the incumbent fluid cannot affect the other parti- cles, which are then urged equally in every direction. Iöss of impulse which a current sustains from the attrition of the sides of a pipe or of a canal, is occasioned by the incessant stoppage of the extreme particles. This consumption of force must hence be compounded of the number of particles arrested in a given time, and of their velocity, and is therefore propor- tional to the square of their velocity. But the retardation of the current must likewise depend on the extent of impeding influence, that is, on the length of the pipe, and on the relation which the interior surface bears to its whole capacity. But the square of the velocity, with which the stream first issues from the cistern, being proportional to the altitude of the in- cumbent column, a certain part only of this constant inciting force is employed in generating the initial velocity, while the rest is expended in renewing the velocity as fast as it expires, along the sides of the channel, or in maintaining through the mass a general uniform flow. It has been ascertained by experiment, that water has its celerity diminished eight times by passing through a tube of an inch in diameter, and 204 feet long. Of sixty-four parts of compression, one part only had therefore created the motion of the fluid, while sixty-three parts are required to support it. This motion is hence renewed eight times during the passage of the water, or at the interval of 253 feet through the whole extent. The In each of these successive transits, all the central particles must be thrown towards the sides of the pipe, whence they are again drawn into the body of the stream, and there ; acquire new celerity. The celerity is lost and regained, close to the interior surface, within a very small but limited space. Wherefore, from the fundamental principle of dynamics, the square of the velocity acquired or extinguished must be as the product of the inciting force into the limit of its action. to the extent of surface compared with the capacity of the pipe, or it is directly as the length, and inversely as the diameter. The square of the velocity hence suffers a diminution proportioned But the pressure of the water has no effect whatever in causing this reduction. Thus, resuming the same example, let the pipe of an inch wide and 204 feet long be fed by a cistern of ten inches altitude, and the quantity of discharge noted. Raise this cistern now to twenty inches, and turn up, by a soft bend, the farther extremity to the height of ten inches, and the cor- responding flow will be still the same. Increase the altitude of the cistern to one hundred inches, while the remote end is bent with an elbow to the height of ninety inches, leaving still the same excess or exciting force, and the quantity of discharge will be found not to vary. Fluids by their pressure may be conveyed over hills and valleys in bended pipes, to any height not greater than the level of the springs whence they flow. Of this fact, the ancients were altogether ignorant. The expedient of aqueducts, (vast rows of arches, one above another between two hills,) was therefore resorted to at an enormous expense, both of money and labour, in order to convey water across the valley beneath.-But we have already, under the word Aqueduct, said so much on the conduit of water, that we shall here confine ourselves chiefly to the modern method of laying down service pipes for the supply of water to cities.- The pressure of fluids affords the means of conveying them from one place to another, although considerable inequalities in the surface of the ground intervene between the places. Water, for example, may be conveyed from a reservoir across a valley, or to any distance, either by means of open canals, aqueducts, or closed pipes, provided the reservoir be situated somewhat higher than the level of the place at which it is wanted. - . Thus, suppose, there is a spring at A, on one side of the valley D, as in the annexed figure, and a house on the other, - at which the water of the spring is wanted; if the house is found to be lower than the spring, the water may be conveyed to it by an iron or leaden pipe, proceeding from the spring across the valley, as in the figure. The depth of the valley must; however, be taken into consi- deration, in order to make the pipe of sufficient strength to resist the pressure of the water, which depends entirely on its depth. If the lowest part of the valley be considerably under the spring, the pipe must be made very strong at the lowest part, or else it will burst. When an uninterrupted declivity cannot be obtained, it is neeessary to employ pipes, which may be bent upwards or downwards at pleasure, provided that no part of them be more than thirty-two feet above the reservoir, and when the pipe is once filled, the water will continue to flow from the lower orifice; but it is best in all such cases to avoid unnecessary angles; for when the pipe rises and falls again, a portion of the air, which is always contained in water, is frequently collected in the angle, and very materially impedes the progress of the Water through the pipe. When the bent part is wholly below the orifices of the pipe, this air may be discharged by various methods. . The ancients used small upright pipes, called colum- ºnaria, rising from the convexity of the principal pipe to the level of the reservoir, and suffering the air to escape without Wasting any of the water. It may, however, frequently be inconvenient or impossible to apply a pipe of this kind; but the same purpose may be answered, by fixing on the pipe a box containing a small valve, which opens downwards, and is sup- ported by a float, so as to remain shut while the box is full of water, and to fall open when any air is collected in it. Thus A, in the following figure, is a box of this kind, with a valve, supported by a hollow ball, for letting out air from pipes, when it is below the level of the reservoir. * If the pipe were formed into a syphon, having its flexure above both orifices, it would be necessary to bend it upwards at the extremities, in order to keep it always full; but in this case the accumulation of the air would be extremely inconve- nient, since it would collect so much the more copiously, as the water in the upper part of the pipe would be more free from t pressure; and neither of the methods which have been mentioned would be of any use in extricating it. . It has been usual in such cases to force a quantity of water violent- ly through the pipe, in order to carry the air with it; but it might be still simpler to have a pretty large vessel of water screwed on to the pipe, which would not be filled with air for a considerable time, and which, when full, might be taken off and replenished with water. This contrivance is represented by the figure, where B is a vessel of water, serewed on for receiving the air, to be replenished with water as it becomes empty. When the water from a reservoir is conveyed in long horizontal pipes of the same aperture, ; the discharges made in equal times are nearly in the inverse ratio of the square roots of the lengths. Thus, if there be two pipes of the same aperture, one of which is 49 and the other 36 feet long, the discharge from the former will be to that from the latter, as the square root of 49 to the square root of 36, or as 7 to 6; therefore, the quantity l discharged from the shorter pipe will be # of that discharged H Y D H Y D 493 DICTIONARY OF MECHANICAL SCIENCE. from the longer one. It is here supposed, that the pipes to which this rule is applied, are not very unequal in length ; and even then the rule only affords an approximation not deduced from principle, but derived immediately from experiment. Bossut has given a table of the actual discharges of water pipes, as far as the length of 2340 toises, or 14950 English feet, but it is too extensive to be inserted here. If the quantity of water discharged by a pipe of a given length, be known by experiment, we may find, by the foregoing proposition, the quantity discharged by a pipe of any other length. The diminution of velocity being greatest when the head of water is small, we may conceive the head of water to be reduced to such a degree, that the velocity with which the water enters the pipe is not sufficiently powerful to overcome the resistance arising from the friction upon the pipe, and the mutual cohesion of the particles of water. In order to examine this point experimentally, M. Bossut employed a head of water only 16 lines, from which the water ſlowed into two pipes, whose length were a hundred and eighty feet. In this case, the water was discharged in the form of a narrow fillet, and the drops succeeded each other almost as if they were insulated bodies. Hence it follows, that in order to have a perceptible and continuous discharge from pipes, there should be a head of water of about 20 lines in 180 feet. If the current of water, however, be very large, such a great declivity as this will not be necessary. Pipes are usually made of wood, of lead, or of cast iron: but commonly of lead; and of late tinned copper has been em- ployed with considerable advantage. A pipe of lead will bear the pressure of a column of water 100 feet high, if its thickness be one-hundredth of its diameter, or even less than this; but when any alternation of motion is produced, a much stronger pipe is required; and it is usual to make leaden pipes of all kinds far thicker than in the above proportion. We have already illustrated the velocity and discharge of water through pipes and conduits, and noticed the retardation to which the fluid is exposed. Now, if we conceive a rectan- gular channel to have a section equal to the circle of the pipe, while its bottom and sides are equal to the circumference, the . retardation of the current would be exactly the same. Hence, the fourth part of the diameter will be equal to the quotient of the section, by the compound measure of its bottom and sides, which is called the mean hydraulic depth; and hence much less obstruction is encountered along an open course, than within a close pipe, or about three times the square root of the depth. - The motion of a fluid is further obstructed by any violent change of celerity or direction; whether the channel be con- tracted or enlarged, the change is unavoidably attended by a proportional loss of impulsion. Any sharp flexure of the pipe or conduit will occasion a still greater waste of the inciting force. The diminution of the square of the velocity is ex- pressed by the product of that square into the square of the sine of the angle of deflexion, divided by the constant number 270. With a deflexion of 30 degrees, the velocity would there- fore lose only the 2160th part; but if the tube branched off at right angles, the retardation would amount to the 540th part. Every contraction or enlargement of the pipes requiring a corresponding change in the celerity of the water, must like- wise create an expense of force, though this effect could scarcely be reduced to calculation. Water is subject in its motion through pipes to another impediment, owing to the air which constantly separates from it and collects in all the upper sinuosities of the train, as already noticed. This accumulation is most copious whenever the supply of water happens to be insufficient to fill the whole extent of cavity. To remedy the defect, boxes of cast iron are fixed above the principal incurvations of the pipe, to receive the compressed air, as represented in the last figure, and by the operation of a valve or of a cock, gradually to discharge it, without allowing any of the water to escape. Of such air- vessels, with a cylindrical form, four feet high and eighteen inches wide, fourteen have been made, for the pipes which supply the city of Edinburgh with water. These being screwed at the summit of each declivity, are opened, every two or three days, by the surveyor of the works. The present supply of Edinburgh, says Leslie, is brought by two trains of cast iron pipes; one from Green Craig to the Castle Hill, 26,930 feet long, and 7 inches in diameter, under a head pressure of 404 feet; the other from Comiston to Heriot’s reservoir, 13,520 feet long, and 5 inches wide, under a load of 88 feet. The former, when fully charged, is found to deliver 46, and the latter only 10 cubic feet, every minute, making together 56 feet, which furnishes a supply of 80,640 cubic feet in the space of twenty-four hours. This amounts to scarcely three-fifth parts of the quantity assigned by the formula. The deficiency must be attributed wholly to the imperfect execution of those pipes, their uneven interior surface, and their frequent abrupt and sudden bendings. The waterworks now designed for the complete supply of Edinburgh, are conducted in a much finer style, and at vast expense. The several pieces of pipe are nicely fitted together by spigot and faucet, all the accidental prominences over the inside being carefully removed by chiseling. The pipes exhibit no visible incurvation, and they generally are laid with a gentle uniform slope, the ground on which they rest being lowered in some places and raised in others. From ‘the Crawley Spring to Straiton March Fence, the distance is 18,300 feet, with a fall of 65 feet; and, in this line, the pipes vary from 20 to 18 inches, in diameter. The next train has a diameter of only 15 inches, but runs, with a fall of 286 feet, through an extent of 27,900 feet, being conducted by a tunnel of 360 fathoms length through Heriot's Ridge, and by another of 290 fathoms through the Castle Hill, till it reaches the level of Prince's-street. This elaborate system of pipes delivers nearly the measure of water indicated by the formula. It has been computed, that the quantity of rain which falls annually over any city, if carefully collected and deposited to purify in cisterns, would be sufficient for the supply of the inhabitants, at least in all the essential domestic and culinary purposes. Venice has abundance of fine soft water procured in this way; and the store seldom fails, except in dry seasons, when it is recruited from the river Brenta. The roof of a lofty house in Paris, containing at an average 25 lodgers, might deliver annually 1800 cubic feet of rain water, which would furnish each individual daily the fifth part of a cubic foot, or about thirteen pounds avoirdupois, -rather a scantity provi- sion, to be sure, according to our modern ideas of comfort; yet Prony reckons ten litres, or the thousandth part of his modulus, as a sufficient supply, amounting only to about twenty-two pounds. See the word AQUEDUCT pp. 51–53. Since, from a pipe of the same diameter, the discharge in every case depends on the relation of the altitude of the source to the length of track, a lower elevation may frequently be preferred in conjunction with a shorter train. The dimin- ished obstruction, in such instances, compensates for the infe- rior pressure. From any point of an inclined plane, the pipe would convey exactly an equal body of water. In the same train, the quantity of discharge being as di, must increase in a faster ratio than the mere section of the pipe. Hence the manifest advantage of employing large pipes. For the same reason, aqueducts or open conduits are in many situations to be preferred. When these convey large streams of water, the attrition of the sides and bottom is comparatively small, and they require very little descent. Such durable structures are common in the south of Europe, and often display much archi- tectural symmetry in their extended and imposing ranges of arcades, Circular Basins and Conduit Pipes.—These basins and pipes bear a lateral pressure proportioned to the altitude of the column; but in consequence of the curvature, this pressure will occasion likewise a longitudinal strain or distention. And the lateral pressure of the water against each ring of the cylinder, as in the annexed figure, B A C, produces the same effect as a longitudinal force applied to it equal to the weight of a prism resting on a base which has the breadth of that ring, with the radius O B for its thickness. Hence, the strength of the cylinder is in the com- pound ratio of the altitude of the water, and of its own radius or diameter. Similar pipes will therefore bear equal pressures, their thickness being pro- 6 K ,494 H Y D H Y D DICTIONARY OF MECHANICAL SCIENCE. portioned to the diameter. For example, a pipe 1 foot diame- ter, and half an inch thick, will resist the thrust of the same alti- tude of water as a pipe of the same materials 2 feet wide and 1 inch thick. Lead, however, has only one-tenth of the tenacity of cast iron, and therefore a pipe of that soft metal will, in similar circumstances, require to have ten times greater thick- ness in proportion to its diameter, than one of iron. Such is the case with a pipe of elm, while one of freestone would require to have its thickness doubled. A pipe of cast iron, 15 inches diameter, and # inch thick, will bear a pressure equal to 600 feet in altitude; and a pipe of the same diameter, but 13 inch thick, will bear a pressure or strain of 1000 feet, the cohesion of cast iron being 6000, or in its greatest reduced state 2600 lbs. A very proper way to try the strength of such cast iron pipes is, by means of a large forcing pump, and every pipe of the above dimensions that would not bear the pressure of a column of water respectively of the altitudes of 400 and 800 feet, ought to be rejected as betraying flaws, and being unsafe. A pipe of lead 43 diameter, and ; of an inch thick, sustained only the thrust of 172 feet in height of water; a pipe of oak 15 inch bore diameter, and 2 inches thick, will sustain a column of water only 179 feet high, the cohesion of oak being 2316 lbs. The cohesion of Portland stone is only 857 lbs. and therefore a pipe 1 foot diameter, and 1% inch thick of that material, will sustain a pressure of only 62 feet; hence the failure from frac- ture and chipping, of those handsome stone pipes so ingeni- ously cut out of blocks of freestone in a series of cores, by the application of a circular saw, as in this figure,” where O B represents T H.R. the largest or first cut, O C the bore of the second cut, and O D the third pipe squared out of the block P O R.T. The same principles regulate the B strength of a circular basin confin- ing water. . The perpendicular pressure against the wall depends indeed merely on the altitude of the fluid, without being affected by F O the volume; but the longitudinal effort of the thrust, or its tendency to open the joints of the masonry, is measured by the radius of the circle. To resist that action, in very wide basins, the range or course of stones, along the inside of the wall, must be proportionally thicker. On the other hand, if any opposing surface present some con- vexity to the pressure of water, the resulting longitudinal strain will now be exerted in closing the joints, and consoli- dating the building. Such reversed incurvation is hence gene- rally adopted in the construction of dams, the bend inwards of the arc being about the eightieth part of the length of its chord, while the exterior boundary is made rectilineal. The various Hydraulic Machines, as the Syphon, Archimedes' Screw, the Tympanum, the Persian Wheel, Chain and Spiral Pumps; the Hungarian Machine, Fire Engine, Hydraulic Ram, the Danaide, &c. are all described in various parts of this Dic- tionary under their respective words. HYDRQCELE, in Surgery, any hernia arising from water, but is particularly used for such a one of the scrotum. HYDRODYNAMICS, treat of the powers, forces, and veloci- ties, of ſluids in motion. - - HYDROGEN. It had been long known to the chemists, that a vapour of air was disengaged during the solution of cer- tain metals in muriatic or dilute sulphuric acid, that it burnt at the mouth of the phial, and if mixed with atmospheric air, exploded when kindled by a match. This substance forming water when combined with oxygen, and being therefore the radical of that compound, the name hydrogen was given to it at the formation of the new nomenclature. It is always ob- tained from the decomposition of water, as it cannot, from other substances in which it exists, be easily disengaged in perfect purity. Some substance is made to act on water, which exerts an attraction to the oxygen, without combining with the hy- drogen, when of course the hydrogen is disengaged, and passes into the elastic form. If a coil of iron wire, or a quantity of iron filings, be put into an iron or coated glass, or earthen tube ral temperature. to meet and inflame, and so to continue for several days. which is placed across a small furnac", and surrounded with burning fuel, so as to be brought to a red heat, on distilling water from a retort connected with it, the vapour, in passing over the surface of the ignited iron, is decomposed, the iron attracts its oxygen, and hydrogen gas issues from the extremi- ty of the tube. - This process is a troublesome one, and by the agency of an acid, water is decomposed as rapidly by iron or zinc, at a natu- Zinc affords the hydrogen in the greatest purity. One part of it, in small pieces, is put into a retort, or a bottle with a bent tube adapted to it; two parts of sulphuric acid, previously diluted with five times its weight of water, are poured upon it, an effervescence is immediately excited, hydro- gen gas escapes, and is to be collected in jars filled with water. These co-operating, produce a ternary combination, while the hydrogen gas is disengaged. Hydrogen gas is permanently elastic. When collected over water, it is observed to have a peculiar smell, slightly fetid. It is the lightest of the gases, and indeed the lightest substance whose gravity can be ascer- tained by weighing. Its specific gravity varies considerably, according to its state with regard to humidity. When it has been transmitted through water, it is about ten times lighter than atmospheric air; when it has been received over quicksil- ver, and exposed to any substance which attracts water strong- ly, it is near 13 times lighter. It is from this levity that it was applied with success to the construction of balloons. After it was first discovered that oxygen and hydrogen gases by combustion produced water, the French chemists, to verify the experiment, made an immense reservoir of oxygen gas, and another of hydrogen gas, and caused a small stream from º The result was a large quantity of excellent water. - • The chemical property by which hydrogen gas is most emi- nently distinguished, is its great inflammability. When an ignited body is approached to it in contact with the atmo- sphere, it is immediately kindled, and continues to burn while the air is admitted; if previously mixed with atmo- spheric air, and a burning body approached to the mixture, or an electric spark sent through it, it instantly inflames with detonation; and when it has been mixed with oxygen gas, the detonation is more violent. Though hydrogen gas be inflam- mable, it is incapable of supporting the combustion of other inflammables.i. This gas is incapable of supporting animal life by respiration; an animal immersed in it is soon killed. At the same time, it does not appear to be so positively deleteri- ous as the other noxious gases. Rosier, even after expelling the air from the lungs, breathed hydrogen gas for several respirations. It is not noxious to vegetable life; at the same time, it appears to contribute little to the nourishment of plants. Hydrogen gas is so sparingly soluble in water, that when agitated with it, it suffers no perceptible diminution of volume. The affinities of hydrogen seem principally exerted towards inflammable bodies. Hydrogen gas is found collected often in mines, derived probably from the decomposition of water by metals; it is known to the miners by the name of fire damp, and is often the cause of accidents from exploding on the approach of an ignited body. It is also extricated from stag- nant water, and from marshy situations, from the slow decom- position of vegetable and animal substances. From its levity it has been supposed that the quantity of it thus produced at the surface of the earth, will rise through the atmosphere and occupy the higher regions; and on its presence, some of the phenomena of meteorology, particularly the sudden appear- ance of some fiery meteors, have been supposed to depend. HYDROGRAPHY, the art of measuring and describing the sea, rivers, lakes, and canals. - HYDROMETER, an instrument for measuring the density, gravity, &c. of water and other liquids; that which is designed simply for ascertaining the specific gravity of different waters, is more commonly called an AREOMETER, or waterpoise; the term hydrometer being more commonly employed to denote an instrument for measuring the specific gravity of spirits, though it is sometimes used indifferently for either. Mr. Clarke constructed an hydrometer, shewing whether any spirits be proof, or above or below proof, and in what degree. This instrument was made of a ball of copper, (because ivory H Y D H Y D 495 DICTIONARY OF MECHANICAL SCIENCE. ' imbibes spirituous liquors, and glass is apt to break,) to which is soldered a brass wire about a quarter of an inch thick; upon this wire is marked the point to which it exactly sinks in proof spirits; as also two other marks, one above and one below the former, exactly answerable to one tenth above proof and one tenth below proof. There are also a number of small weights made to add to it, so as to answer to the other degrees of strength besides those above, and for determining the speci- fic gravity of different fluids. Dr. Desaguliers’ hydrometer determines the specific gravities of different waters to such a degree of nicety, that it shews when one kind of water is but the 40,000 part heavier than another. It consists of a hollow ball of about three inches in diameter, charged with shot to a proper degree, and having fixed in it a long and very slender wire, of only the 40th part of an inch in diameter, and divided into tenths of inches, each tenth answer- ing to the 40,000th as above: Nicholson made an improvement by which the hydrometer is adapted to the general purpose of finding the specific gravity both of solids and fluids. g º- A is a hollow ball of copper, B a dish affixed to the ball by a short slender stem D ; C is another affixed to the opposite side of the ball by a kind of stirrup. In the instrument actually made, the stem D is of hardened steel # of an inch in diameter, and the dish C is so heavy as in all cases to keep the stem vertical when the instrument is made to float in any liquid. The parts are so adjusted, that the addition of 1000 grains in the upper dish B, will just sink it in distilled water, at the tempera- ture of 60° of Fahrenheit's thermometer, so far that the surface shall intersect the middle of the stem D. Let it now be required to find the specific gravity of any fluid. Immerse the instrument in it, and by placing weights in the dish B cause it to float, so that the middle of its stem D shall be cut by the surface of the fluid. Then, as the known weight of the instru- ment, added to 1000 grains, is to the same known weight added to the weight used in producing the last equilibrium, so is the weight of a quantity of distilled water displaced by the floating instrument, to the weight of an equal bulk of the fluid under examination. And these weights are in the direct ratio of the specific gravities. Again, let it be required to find the specific gravity of a solid body, whose weight is less than 1000 grains. Place the instru- ment in distilled water, and put the body to the dish B. Make the adjustment of sinking the instrument in the middle of the stem, by adding weight in the same dish. Subtract those weights from 1000 grains, and the remainder will be the weight of the body. Place now the body in the lower dish C, and add more weight in the upper dish B, till the adjustment is again obtained. The weight last added will be the loss the solids sustain by immersion, and is the weight of an equal bulk of water. Consequently the specific gravity of the solid is to that of water, as the weight of the body to the loss occasioned by the immersion. This instrument was found to be sufficiently accurate to give weights true to less than one-twentieth of a grain. - HYDROPHILUS, in Natural History, a genus of insects of the order of coleoptera, that inhabit ponds and stagnant waters, where they swim with much dexterity; they fly abroad by night in search of other waters. HYDROPHOBIA, an aversion or dread of water; a terrible symptom of the rabies canina. . . - HYDROSCOPE, an instrument anciently used for the mea- suring of time. The hydroscope was a kind of water-clock, consisting of a graduated cylindrical tube, conical at the bot- tom, or marked out with divisions, to which the top of the water becoming successively contiguous as it trickled out of the vor- tex of the cone, pointed out the hour. HYDROSTATICS, is the science which treats of the mecha- nical properties of fluids. Strictly speaking, the weight and equilibrium of fluids at rest, are the objects of this science. When the equilibrium is destroyed, motion ensues; and the i. which considers the laws of fluids in motion, is hy- Taul ICS. A fluid is a body whose parts yield to any impression, and in yielding, are easily moved against each other. Fluids are of two kinds; non-elastic and incompressible fluids, such as water, oil, mercury, &c. : and elastic and compressible fluids, such as air of different sorts. - Modern philosophers suppose that a certain portion of heat, combined in some way or other with bodies, occasions fluidity, and that the relative portions of heat contained in fluids and solids, is the cause of the difference between them. And it is from the imperfect cohesion of fluids, that, when in small quantities, they arrange themselves in a spherical manner, and form drops. A portion of fluid gravitates in another when surrounded by a larger portion, in the same way as if it were in air. But fluids have this remarkable property also, that they press not only in common with solids, perpendicularly, but also upwards, side- ways, and in every direction equally. Take a glass tube open at both ends, and stopping one end with your finger, immerge the other in water. The water will be prevented from rising far in the tube by the air which is contained in it; but if you take away your finger from the upper end, the air within the tube will be suffered to escape, and the water will rise in the tube to the same level as it is in the vessel, being pressed upwards by the surrounding water. The same effect will take | place, if you incline the tube in any direction; or if you make use of tubes bent in any manner; still you will find that the water within them will rise to the same height as in the external ves- sel. From this property it is, that if you bore a hole in the side of a vessel filled with water, the fluid will spout out. . A fluid presses in proportion to its perpendicular height, and the base of the vessel containing it, without any regard to the quantity: for as fluids press equally in every direction, the horizontal bottom of a vessel sustains exactly the pressure of a column of fluid, whose base is the area of the bottom of the vessel, and whose perpendicular height is equal to the depth of the fluid. - - The pressure exerted against the bottom of a vessel is in nowise augmented by its spreading shape. Thus, in the vessel A B, fig. 1, the bottom B C sustains a pressure equal to the Fig. 1. Fig. 2. A. CF IF ~~~~ O B CC G. Eºſ column whose base is C B, and height CE, and not as the whole quantity of fluid contained in the vessel. Also in the vessel FG, fig. 2, the bottom G PI, sustains a pressure equaſ to what it would be if the vessel were as wide at the top as it is at the bottom. • : This very singular and important conclusion, that the pres- sure of a liquid upon the bottom of any vessel depends merely on its altitude and the surface of its base, might be derived from simpler but indirect considerations. Suppose the por- tion of a liquid, which encircles the vertical cylinder FC B, + (as in the annexed figure,) to be frozen or p converted into a solid substance, but without changing its density; the pressure of this congealed mass would evidently continue the same as before, and therefore, the bot- tom has only to sustain the weight of the cylindrical column which rests immediately upon it. If the lateral ice were again melt- ed, it would assume its horizontal thrust, which could not alter the vertical pressure of the liquid. In like manner, if FGM were , a cylinder of liquid resting upon a circular Bºls base, and the portions FG K, L H O about the sides were rendered solid or congealed, without alteration of density, the remaining portion G. K. LM will evidently exert 496 H Y D H Y D IOIGT to NARY OF MECHAN 10 AL SCIENCE, * the same pressure as before ; and the incurved sides K.G., L H produce an effect analogous to the load of the supposed frozen . - | and the entrance of the air and escape of the liquid are equally masses FG K, L H O. Suppose any interior portion of a liquid to become solid; it would evidently remain in the same state of indifference or equilibrium as before. It must therefore be borne up by the vertical pressure of the fluid with a force just equal to its weight, or the weight of the liquid whose place it occupies. Conceive this congealed mass to have its gravity augmented or diminished; it must evidently be pulled downwards or up- wards by the difference between this force and the weight of an equal bulk of the liquid. . Substitute any solid body instead of this block of ice, and the loss of weight it suffers by the immer- sion will be equal to that of the volume of fluid which it displaces. This fundamental property, first detected by the genius of Archimedes, may be demonstrated by a stricter process of reasoning. Let a cylindrical body FEG H, be plunged verti- cally in a vessel C A B D, filled with water or any other liquid; the lateral pressure, acting equally around the axis, will evi- dently produce a complete balance of efforts. But the cylinder will be pushed upwards by a column of fluid having IE for its altitude, and the circle E G for its base, and pressed down- wards again by the circular column I FH K. The solid is, therefore, buoyed up by the excess of the former force above the latter, or by the weight of an equal cylinder FE G H of the liquid. In fact, the solid body loses by immersion, just as much weight as that of an equal volume of the surrounding fluid; and, on this principle, is founded the method of ascer- taining the density of a body, or the relation of its weight to its bulk, which, in reference to some common standard, is termed its specific gravity. Water, at its state of greatest con- traction, is preferred as the most convenient unit of compari- son, the density of other bodies being reckoned in decimal parts. The Hydrostatic Balance is generally used for this pur- pose. The substance to be examined may be either liquid or solid. The specific gravity of liquids is easily determined, by means of a ball or pear-shaped lump of glass or crystal, either partly hollow or loaded. This poise, suspended by a hair or fine thread, is weighed in vacuo or in air, then in pure water, and next in the particular liquid; the loss of weight which it suffers in water is to its loss in the fluid under trial, as unit to the specific gravity of this fluid. The calculation is sometimes carried to five places of decimals; though it is seldom safe or expedient to push them beyond three figures. If the lump of glass were ground to such a size as to lose exactly a thousand or ten thousand grains in distilled water, no computation would be required, its loss of weight, by immersion, indicating at once the specific gravity of the liquid. This leads to what is called the Hydrostatical Paradox, which is, that a small quantity of fluid may be made to coun. terpoise the greatest quantity. Thus, if to a wide vessel A B, you attach a tube C D communicating with the vessel, ca and pour water into either of them, it will | always stand at the same height in both, & s º consequently there is an equilibrium be- iſſ tween them. And of whatever shape the vessels are, the effect will be the same. This fact is confirmed by a variety of strik- ing experiments, and forms an essential consideration in all water works. But the principle extends its influence to masonry; for if the smallest quantity of water should lodge to a considerable height in the gravel, sand, or loose earth, close behind a wall or solid embankment, it would exert a lateral pressure sufficient to push the solid materials from their base. Hence, a sudden shower, great devastation, the thinnest vein of water collected in a perpendicular crevice, will split the hardest rock, and hurl the fragments to its base. Thus hydrostatic pressure is the silent, but irresistible agent, which nature employs in the gradual demolition of mountains. . A. Perpetual Syphon, which possesses the faculty of making liquids pass from one vessel to another, even after the vessels are empty and the action ceases, has two unequal arms; after entirely plunging it into any liquid, in order that it may be filled, and taking care that both orifices are constantly im- mersed, each extremity of the syphon is introduced into a small vase or reservoir, filled with the same liquid, in which is plunged each end. Thus the immersion of the two ends is constant: prevented; the syphon, always full, is in constant action, by only immersing one of its branches, without the aid of air, opening or shutting cocks, &c. What is remarkable in this invention, is the fact, that as soon as one vessel is empty it is filled again from the other; and so on continually. The Hydrostatic Bellows.-This instrument is perhaps the best yet invented for demonstrating the upward pressure of fluids, and it is fully illustrated under the word Bellows, & 104. - p The Hydrostatic Balance has been already illustrated; and Specific Gravities were handled under the word GRAvity. Solid Bodies Floating on Fluids.—A solid floating on a fluid specifically heavier than itself, will be in equilibrio, or will rest, when it has sunk so far that the weight of the fluid dis- placed is equal to the weight of the whole solid, and when the centres of gravity of the whole solid, and of the part immersed, are in the same vertical line. * - Hence, every solid, specifically lighter than a fluid which has an axis that divides it into two similar and equal parts, when placed in a fluid with its axis vertical, may sink to a position in which it will remain in equilibrio; that is, without turning' either to the one side or the other. - - In such bodies there are always two opposite positions of equilibrium; but there is only one of them in which the body can float permanently. - When the equilibrium of a floating body is disturbed, or when the centres of gravity of the whole, and the part immersed, are not in the same vertical line, the body will revolve on its axis, till it come into the position where these two points are in the same vertical line. - There are some bodies that in every position these tw points are in the same vertical line. A homogeneous sphere, or globe, is a body of this kind; and so is a cylinder floating with its axis horizontal. These bodies have no tendency to maintain one position more than another; and their equili- brium, or floating position, is called the equilibrium of in- difference. - Some floating bodies, when their equilibrium is disturbed, return to their steady position after a few oscillations back- wards and forwards. Others, when ever so little disturbed, do not resume their formør position, but turn on their centres of gravity, till they come into another position, when they are again in equilibrio. In the first case the equilibrium is said to be stable, in the latter case to be unstable, and then the body is said to overset. - - - When a floating body is made to revolve from the position of equilibrium, if the line of support (that is, the vertical line passing through the centre of gravity of the immersed part) move so as to be on the same side of the line of pressure (or the vertical passing through the centre of gravity of the whole) with the depressed-part, the equilibrium is stable, and the body will resume its former position. But if the line of support is on the same side of the line of pressure with the elevated part, the equilibrium is unstable, and the body will overset.* When a floating body revolves about a given axis, the posi- tions of equilibrium, through which it passes are alternately those of stability and instability: for between a state in which a body has a tendency to remain, and another in which it has also a tendency to remain, as these tendencies are opposite to one another, there must be an intermediate position in which the tendency to remain is equal to nothing, or the body will revolve on its axis. . - . If the form and size of a body, floating in a fluid, be known, and its altitude above the surface, and the specific gravity of the fluid be also known, its stability may be calculated. Having given the general principles of this branch of science, we may explain in more popular speech a few of the leading characteristics in the doctrine of fluids. First then, every sub- * The centre of gravity of any body is that point upon which the body, when acted upon only by the force of gravity, will balance itself in all positions. This will be more fully explained when we come to treat of Mechanics. H Y B H Y D 497 DICTIONARY OF MECHANICAL SCIENCE. stance appears composed' of an assemblage of atoms, con- nected together by a system of mutual attraction and repul- sion; in solids, the atoms resist every change of figure; in fluids; they yield to the slightest external pressure, because their particles are loosely connected. A solid reduced to a plane easily folds up in one direction; if reduced to filaments it will bend every way, without breaking; crumbled to dust or powder, the aggregate particles submit to any external im- pression, and evince no sympathy of concatenation. .. A solid body, subjected to a compressing force, undergoes a proportional contraction, but recovers its volume after this contraction is withdrawn. But if the compression be urged beyond a certain limit, the substance will be crushed under the load, and will suffer a complete dissolution. A fluid, however, enclosed in the chamber of a very strong metallic vessel, is found to be capable of withstanding the greatest pressure we can command, though its contractions are comparatively more extensive; and it always returns with unimpaired vigour to its former condition, the moment such external force has ceased to act. The constitution of a fluid remains unaltered under the most enormous loads, and its several portions, at all times, separate and reunite with extreme facility. Whether the fluid has a liquid or assumes a gaseous form, it can equally bear any compression, the corresponding contraction of the latter being only much greater than that of the former. If the minutest subdivision of a solid contributes nothing to fluidity, neither will any supposed smoothness or globular shape of the particles confer that character. Exact spherules might procure lubricity on a plane, but, among one another, they will become implanted, and affect certain configurations, as manifested in the common piling of shot. The absolute contact of the particles is besides inadmissible, since all bodies whatever seem to be capable of indefinite condensation. But fluidity occurs in very different degrees. Any disturb- ing impression is more quickly obeyed by one liquid than by another; by water, for instance, than by oil or treacle. All the possible shades of softness, in fact, might often be traced from a solid to a ſluid substance. The application of heat generally promotes fluidity. Thus, honey in winter is a can- | died or friable solid; in the spring it melts down; but as the summer advances, it gradually loses its viscidity, and flows more freely. Oil seems affected in the same way, and hence the practice in Italy of depositing it in casks for exportation during the winter season, when it is thickest and least pene- trating, But water itself, and other liquids, not excepting mercury, have their fluidity likewise augmented by heat, as evinced in their quickened flow through capillary tubes. If an angular bit of glass be held in the flame of a blowpipe, it will become gradually rounded, as the heat penetrates and softens the mass. In like manner, a fragment of sealing-wax loses its rough exterior, and assumes a regular curved surface, on approaching it to the fire. But the centre of curvature is the point to which the combined attractions of the outer range of particles must be directed. Since this point retires, there- fore, from the surface with the progress of softness to ſluidity, the mutual connexion of the integrant molecules must be exerted over a much greater extent in fluids than in solid sub- stances. This inference appears to afford likewise an expla- nation of the facility of their internal motion, so conspicuous in liquids. When the sphere of activity is confined, as in solids, to a very narrow spot, a few particles only are con- nected by their sympathetic tendencies. Any internal dislo- cation will in this case require the approximation of certain particles and the recession of others, which must hence occa- sion the exercise of corresponding repulsive and attractive forces. But these forces, being directed to a small number of centres, will constitute a very unequal group, incapable of gaining a smooth and graduated equilibrium. of inclination would produce a violent effort to attain a new position of repose. On the other hand, when the sphere of activity embraces a multitude of particles, as in the compo- sition of fluids, the slightest mutual derangement will be suffi- cient to accommodate every variation of external impression. The most minute deviation of each particle would, by such prodigious repetition, amount to any required change of direc- tion. In their dislocations, the particles are almost uncon- * a Every change strained, and need scarcely approach or recede; the repulsive and attractive forces evolved become therefore extremely small, and by their multitude produce in every position nearly a perfect counterbalance. A fluid is hence fitted to obey any impression with the utmost facility. But whatever may be the system of forces that connects the fluid atoms, the properties of the compound are deducible; from the absolute facility with which those ultimate particles receive and transmit external impressions. Suppose a fluid; either gaseous or liquid, to be enclosed in a very broad and extremely shallow cylinder of glass or metal A B (as in the annexed figure,) at the top of which is inserted a tall narrow - tube C D of the same material, and having a plug or piston E micely fitted into it. On push- ing down this piston, the fluid particles un- der it will at first give way, and approach closer to each other. They will, in conse- quence, display a re- pulsive force propor- tional to this mutual approximation. Now, o * + - it is easily seen that points or atoms can never be ranged through space in perfect: straight lines; and, therefore, the pressure will not be confined to the vertical column, but will insensibly diverge in all direc- tions. The particles at F will repel obliquely those at G or at H, and these again will communicate their oblique impres- Sion to other adjacent particles. The whole stratum of . D. fluid, from the orifice C to A and B, must hence continue to recede from the piston, and contract its volume, till the in- tegrant particles have all attained the same mutual distance, and exert the corresponding repulsive energy. A uniform condensation must thus be diffused through the mass, before an equilibrium can take place. This condition obtains equally in liquids and in gaseous fluids, only the contraction produced: from a compressing force, which is so visible in the former, can Seldom be distinguished by ordinary perception in the latter. But a very minute alteration of the volume of a liquid evolves as much force, as an extensive change in the mass of a gase- ous fluid. The pressure exerted by the piston E at the orifice C is therefore equally diffused through the whole of the fluid A B, every particle of which acquires the same intensity of repul- sion. Each point on the surface of the vessel must hence sus- tain an equal effort. If a wide cylinder I K, fitted also with a piston, were inserted at I, the compression resisted by it would be proportional to the space of action or the circle of the orifice. On a supposition that the surface of the piston I were ten times greater than that of E, it would likewise support' a load ten times greater than the pressure applied at E or C. Let the piston I be now removed, while the piston E is con- ceived to act as before. The liquid must evidently rise in the - cylinder I K, (as in the annexed figure,) till its weight be- come equal to the pressure exerted at p|| M||== O Iſlas ; : * # --- Æ/ |É the orifice I. In # £ff == like manner, if an- TE #. other cylinder LM were inserted, the liquid would rise, till its weight was equal to the pres- #|*sure at L. But the pressures at I and L being proportional to those orifices, or the circular sections of the cylinders IK and LM, the altitudes IK and L. M. of the columns themselves must be equal. If a cylinder N. O. were inserted obliquely, the liquid would still rise to the same level; for in this case, the column being partly sustained by thé under 6 L 498 H Y D H Y G. DICTIONARY OF 'MECHANICAL SCIENCE, * side, its weight would, from the property of the inclined plane, be to its pressure at N, as the length O N to the perpen- dicular O P. + - • Let the piston E itself be now withdrawn, and the liquid will mount in the cylinder CD, till its weight becomes equal to the pressure applied at C, and consequently will attain the same altitude as in the other communicating cylinders. Suppose the cylinders to be enlarged and brought nearer to each other, still the same level will be maintained among them. Con- ceive they were even united, so as to compose a single cylin- drical vessel, and the contained liquid would always assume a level surface. Such is the distinguishing character of fluids. It hence follows, that the condensation accumulated at any point of an open liquid mass, and therefore the actual pres- sure exerted there, is proportional to the altitude of the incum- bent column of a supposed vertical tube, or the depth of the point below the surface of the fluid. The pressure of water against the perpendicular sides of any cistern must thus in- crease regularly from the top to the bottom. In a cubical vessel, the pressure borne by each side would be just half the weight supported at the bottom, and consequently the aggregate pressure sustained by all the four sides would be double this weight. f t That the pressure of a fluid is exerted equally every way in Proportion to its depth, may be confirmed by various experi- ments. Thus, having fastened a long narrow glass tube to the neck of a thin bladder, fill this with water till it stand perhaps an inch above, and plunge the whole in a tall jar of water; the liquid will be seen to rise in the tube, and maintain the same altitude, exactly in proportion as the bladder descends. Again, if a high gass tube, spreading below into a wide funnel mouth, to which a loaded plate of brass has been ground and closely fitted, were let down and held in a body of water, at the depth where a cylindrical column of fluid, incumbent upon its broad bace, has a weight equal to that of the plate, this would remain supported. But if a hole were pierced in the side of the tube, admitting a small portion of the water to fill up the funnel, its load would instantly be precipitated to the bottom. On the other hand, if the tube had its funnel mouth turned upwards, and fitted with a thin brass plate surmounted by a very thick cylin- der of Gork; the buoyancy of this cover would be overcome at a certain depth below the surface of the water. But, on letting Water into the funnel, the pressure now exerted under the plate would immediately float it up. * The fundamental principle, that a fluid compressed in a close shallow Vessel exerts the same effort upon every equal portion of the confining surface, was first distinctly stated by the famous Pascal, who even proposed it as a new mechanical power of great efficacy and ready application. If the piston I (p. 497.) were, for instance, an hundred times larger than the piston E, the force of one man pushing down the former would be suffi. Sient to withstand the action of an hundred men upon the latter. Nor did another feature of resemblance escape this acute phi- losopher, that, as in all other mechanical combinations, what is here gained in power is lost in celerity, or, in other words, that the height to which a load is raised is still inversely as the purchase. . Thus, while the piston E descends through one inch, the piston I ascends only the hundredth part of an inch. This $onsideration is essentially the same as the principle of *irtuº velocities, which affords another demonstration ºf the equality of pressure diffused through a fluid. For, if one pound depress the piston E one inch, the piston I will lift an hundred Pounds over the hundredth part of an inch, the momen. tum of the Weight at E being still equal to the opposite momen- tum of the load incumbent at I. The pressure exerted by the fluid upon every point of the surface of the shallow vessel is hence the same. Tºº. Project originally started by Pascal, of applvin this capital property of fluids to the %iº of º #. mechanical engine, has been reduced to convenient practice in 9",9Wn time. . The progress of the arts has now begun to realize all the delicacy of theory. Watt employed, to a certain extent, the Soft compression of air, as the chief agent of his coming engine; while Bramah has Successfully availed him- self. of the constrained energy of wateri •w -4-3 his hydraulic press. gy of water in the construction of HYDROSULPHURET, in Chemistry, the combination of sulphuretted hydrogen with an alkaline or earthy base. They are soluble in water, and crystallizable; the solution is colour- less, while the action of the air is excluded; but when that is admitted, a yellow colour is soon acquired. f HY GROMETER, a machine or instrument to measure the degrees of dryness or moisture of the atmosphere. - There are divers sorts of hygrometers; for whatever bod either swells or shrinks by dryness or moisture, is capable of being formed into an hygrometer. Such are, woods of most kinds, particularly ash, deal, poplar, &c. Such also is cat- gut, the beard of a wild oat, hempen cords, &c. Philosophers have sought also to measure the humidity of the air by the augmentation of weight undergone by certain substances, such as tuft of wool, or portions of salt, by absorbing the water con- tained in the air. But besides that these methods were in themselves very imperfect, the bodies employed were subject to alterations which would make them lose their hygrometric quality more or less promptly. The hygrometer invented by Saussure is free from these inconveniences. The principal piece in it is a hair, which has been divested of a kind of oiliness that is natural to it, by boiling it in water holding in solution nearly a hundredth part of its weight of sulphate of soda. It is known that humidity lengthens the hair, and that the process of drying shortens it. To render both these effects more perceptible, he attached one of the two ends of the hair to a fixed point, and the other to the circumference of a move- able cylinder, that carries at one of its extramities a light index or hand. The hair is bound by a counter-weight of about three grains, suspended by a delicate silk which is rolled in a contrary way about the same cylinder. In proportion as the hair lengthens or shortens, it causes the cylinder to turn in one or the other direction, and by a necessary consequence, the little index turns likewise, the motions of which are measured on the circumference of a graduated circle, about which the index per- forms its revolution as in common clocks. To give to the scale such a basis as may establish a relation between all the hygro- meters constructed upon the same principles, Saussure as- sumes two fixed terms, the extremity of humidity, and that of dryness; he determines the first by placing the hygrometer under a glass receiver, the whole interior surface of which he had completely moistened with water. To obtain the contrary limit of extreme dryness, he made use of a hot and well-dried. receiver, under which he included the hygrometer, with a piece of iron plate likewise heated, covered with a fixed alkali. The scale of the instrument is divided into a hundred degrees. The zero indicates the limit of extreme dryness, and the number one hundred that of extreme humidity. The effects of mois- ture and of dryness upon the hair, are however modified by those of heat, which act upon it, sometimes in the same sense, and sometimes in a contrary one. In observations which require great precision, it is therefore necessary to consult the thermometer; and on this account, the inventor has con- structed from observation a table of corrections. De Luc employed for the construction of his hygrometers a very thin slip of whalebone, which performs the same office as the hair in that of Saussure. He kept this whalebone bent by means of a spring, the action of which he preferred to that of a weight; he determined the degree of extreme humidity, by im- mersing the slip of whalebone entirely under water; and to fix the opposite limit, (that of extreme dryness,) he made use of calcined lime, enclosed with the hygrometer under a glass bell. As the hair hygrometer of M. de Saussure has been almost invariably used by the continental philosophers, as the most accurate instrument for measuring the moisture of the air, any real improvement upon it will be regarded by the experi- mental philosopher as a valuable acquisition to science. The hygrometer of M. Babinet seems to possess this character in no inconsiderable degree, and as a very favourable report upon it has been made to the Academy of Sciences by a very competent judge, M. Fresnel, we shall submit to our readers a drawing and description of it, abridged from the Journal de Pharmacie for April, 1824. This instrument is represented in the annexed figure, where 1, l, 1, 1, is a copper cylinder, resting upon a pedestal, and having large apertures cut out of it. When the interior of the H Y G. H Y P DICTIONARY OF MECHANICAL SCIENCE. 499 instrument is to be shut up from the external air, its upper | part is surrounded with a cylinder of glass, 2,2,2,2, fixed at its two ends (with green wax) to the upper rings which project round the cylinder. Three hairs, 3, 3, 3, fixed to a micrometer screw, 4, 4, placed on the upper part of the instrument, and each stretched by a copper weight, descend into the cylinder, and pass through three holes, in a small horizontal plane, in order that they may be kept separate from each other. On one side of the instrument is placed a small telescope, 5, having a wire in its field, for indicating, with great accuracy, the position of a mark on the copper weights, and ascertaining when the marks have descended to the same point. The object of the micrometer screw is to measure the elonga- tion of the hairs, which it does nearly to the 2500dth part of an inch, by the usual and well-known process. In graduating the instrument, extreme dryness is obtained by means of sulphuric acid, and extreme humidity by means of aqueous vapour; and the elongation of the hairs in passing from the state in which they are saturated with moisture to that of extreme dryness, is measured by the micrometer screw. If this elongation is five millimetres, or about one fifth of an inch, this space is represented by 100 degrees of the scale; so that indths of a millimetre will correspond to one degree of the scale. When the instrument is thus prepared for use, the glass cylinder is removed, and the hairs exposed to the air, the humidity of which will be indicated by the distance of the mark on the copper weight from the beginning or zero of the scale. The advantages of this form of the instrument are thus enumerated by its inventor. • - 1. The extreme delicacy of the indi- cations which are obtained by the tele- 4. scope and the micrometrical screw, and 5 by the use of three hairs, which are *E=}} ! three hygrometers, the mean of the 4;|Hā: 4. changes of which aſſords a much e greater degree of accuracy than if a single one were used. 2. The removal of the error which arises from the friction and play of the axis of the needle in common hygrome- P- ters, as well as from the bending of the hair round the small pulley. 3. The facility of measuring the hy- grometrical elongation of any sub- | stance, whether flexible or not, when reduced to a slender cylinder, and of ſ comparing two hygrometric substances. 4. In this instrument, the three }. hairs, which are three hygrouneters, º "I - agree nearly with one another, while two common hygrometers require very great precaution in order to agree with one another, even less perfectly. 5. This, instrument becomes very portable by stopping the weights at- (L) 3 tached to the three hairs by a small pin - which passes through them, and sup- 1 ports them while they are carried about. * “ . A simple hygrometer inay be formed by means of a flaxen line five -feet Iong; and having a graduated scale fixed to an index moving on a fulcrum. i * The length of the index, from the ful- . crum to the point, should be ten inches; that of the lever, from the fulcrum to the middle of the eye, to which the cord is fixed, two and a half. The air be- coming moist, the cord imbibes its moisture; the line in consequence is shortened, and the index rises. On the contrary, the air becoming dry, the eord discharges its moisture, length- ens,—and the index falls. Hygrometers are constructed in a great varioty of ways, according to the substances of which they are composed, or the manner in which they are designed to act. Our limits however will only allow of touching very slightly on this subject, and we shall therefore confine our remarks to one or two of the best instruments of this kind; after having first illustrated their principle of operation by one of the most simple construction, as follows: g Stretch a common cord or catgut string A B D along a wall, passing it over a pulley B, after having fixed it at one end A, and attached a weight to the other end C, which is made to carry an index or style F. Against the same wall fix a metal graduated plate H I, on which will be indicated the state of the atmosphere by the po- sition of the index, the motion of the - - latter arising solely from the contrac- tion or dilation of the cord, which takes place according to the degree of dryness or moisture of the atmosphere. - This instrument is as simple as can be desired, and its scale of variation may be increased, by passing it over three or four pulleys, as in the annexed figure; but it is far from possessing that degree of accuracy which is so much to be desired in philosophical instruments and observations, and accordingly various other hygrometers have been invented, to remedy the defect of that above described; one great imper- fection of which is, that different instruments, however correct their operation may be, are incomparable with each other; it was therefore a great desideratum to construct them so as to admit of the same kind of comparison as the thermometer and barometer. The most complete in- strument of this kind has been invented by J.F.Daniel, Esq. F.R.S. and to his Meteorological Essays we shall therefore have recourse for the drawings and descriptions of this instrument, when we come to treat on the subject of Meteorology in the sequel of our Dictionary. - HYMENOPTERA, in Natural History, the fifth order of insects, according to the Linnaean system. They are furnished with four membranaceous wings, and with a sting, or a process resembling one. HYPER BOLA, is one of the conic sections formed by the intersection of a plane and cone, when the plane makes, a greater angle with the base of the cone, than that formed by the base and side of the cone, as D A E. * And if the plane be produced so as to cut the opposite cone, another hyperbola will be formed, as d B e, which is called the opposite hyperbola to the former. . The hyperbola, like all the other conic sec- tions, may be treated of in three different ways, viz. 1. As being produced by the intersection of a plane and cone; 2. according to its de- scription in plano; and 3. As being generated - by the motion of a variable line or ordinate along another line or directrix, whereby the properties of the curve are treated of, from the equation by which it is defined. Mechanical Description of the Huperbola, and º , the Method of drawing the Figure. a —1. In the transverse axis AB, Ét-F-I gº ºr ºº & Lººſ ººººººº. *::: E produced, take the foci F., f ; or, S which is the same, take CF, Cf. both = A a or B a ; assume any point I, and with the radii Mé.E AI, or B I, and centres F, f, * describe arcs intersecting in E, - * which will give four points in the curve; then find other points in the same manner, and the curve passing through those points will be the hyperbola required. - 500 H Y S. H Y P. D.ICTIONARY OF MECHANICAL SCIENCE: 2... If one end of a-ruler fM 0, be fastened, at the point f by a pin on asplane; so as to turn free- ly about that point, as a centre; and a thread, FM. O. shorter than- the ruler be fixed, one end at F, and theiother to:the end O. of the ruler: - Then if the ruler fM.Q be turn- ed about the fixed point f, at the same time that the thread, FM O is kept always tight, and its part, MO close to the side of the ruler. by means of the pin M, the curve line A, X, resulting from the mo- tion of the pin M, is one part of an hyperbola; and if the ruler be • º turned, and move on the other side of the fixed point F, the other part AZ of the same hyperbola may be described after the same-manner.—Or otherwise. - - 3. Let C and F be the two foci, and B and K the two vertices of the hy- perbola. Take three rulers CD, Dó, GF, so that C G = GF = E K, and DG = CF; let the rulers CD, GF, be. . of an indefinite length beyond Č and G, and having slits in them.for a pin to move in the rulers, having holes in them at G. and F, by which with pins they are, fastened to the foci of those points, being joined to the points. D and G by the ruler D G. Then if a pin be putin the slits, viz. the common intersection of the rulers CD, and GF, and moved along, causing, the two rulers GF, C D, toº turn about the foci.C and F : that point will describe the portion EQ of an hyperbola. Other mechanical methods of describing this curve may be seen invarious works. - Hyperbolas receive various denominations from certain pecu- liarities in their construction, proportions, &c.; as acute, ambi- genal, equilateral, &c. . HYPER BOLE, in Rhetoric, a figure whereby the truth and reality of things are excessively enlarged, or diminished. HYPERBOLIC LINE, is used by some authors for what we: call the hyperbola itself. ar g - HYPER Bolic Logarithms, or Naperian Logarithms, are a series: of numbers particularly useful in the determination and come- putation offluents, arising from various problems in the higher branches of the mathematics; having, at the same time, the property of common logarithms in facilitating arithmetical ope- rations. *. - These numbers are termed hyperbolic logarithms, because: they express the areas or spaces contained between the assymp- tote and curve of the hyperbola; but as this property is not pecu- liar to this system, they are now more commonly called Naperian: logarithms, from the name of the illustrious, inventor of this method of computation. HYPOTHECATE, in Law. To hypothecate a ship, is to pawn the same for necessaries: and a master may hypothecate. either ship or goods for relief, when in distress at sea. HYPOTHENUSE, in Geometry, the longest side of a right- angled triangle ; or it is that side which subtends the right angle. In every rectilinear right-angled triangle, the square of the hypothenuse is equal to the squares of both the other sides, by the 47th prop. of the first book of Euclid. HYPOTHESIS, in general, denotes something supposed to be true, or taken for granted, in order to prove or illustrate a point in question. HYSTRIX, Porcupine, in Natural History, a genus of qua- drupeds of the order glires. There are five species. H. Crista, or the common porcupine, is about two feet in length, exclu- sively of the tail. It is found in Africa and India, and in the warmer climate of Europe. It is covered on the upper part of its body with variegated spines or quills, which are long and sharp, and which, when irritated, it erects with particular intenseness, and a rustling and alarming noise. Its principal food consists of the bark of trees, roots, and fruit. It produces two at a birth, and if taken young is tamed with considerable facility. Its flesh is eaten not only in Africa but in Italy, and is thought extremely luscious. The Brazilian porcupine is about a foot long, and its tail about a foot and a half, by which it clings to the branches of trees. It is covered with strong, short, and extremely sharp spines, on most of those parts of its body particularly exposed to assault. I. I C E I, or i, the ninth letter and third vowel of the alphabet. When used as a numeral, it signifies no more than one, and stands for $9 many units, as it is repeated times; thus I, one; II, two ; III, three, &c. and when put before a higher numeral it sub- tracts itself, as IV, four; IX, nine, &c.; but when set after it, SQ many are added to the higher numeral as there are I's added ; thus, VI is 5 + 1, or six; VII, 5 + 2, or seven; VIII, 3.H 3, or eight. The ancient Romans likewise used IO for 500, CIO for 1000, IOO for 5000, CCIOO for 10,000, IOOO for 50,000, and CCCIpoo for 100,000. Farther than this, as fliny observes, they did not go in their notation; but when neces. sary, repeated the last number, as CCCIOOO, CCCIOOO for º: CCCIOOO, CCCIOOO, CCCI055 for 300,000; and IAMBICS, certain songs or satires, which are supposed to have given birth to the ancient comedy. The word is applied also to a particular kind of Latin verse, of which the simple foot consists of a short and long syllable. IBEX, in Zöology. See CAPRA. ICE, a brittle transparent body, formed of some fluid frozen or fixed by cold. The specific gravity of ice to that cf water, is in about the ratio of ‘93 to 1; and the capacity for heat as I C E ‘9 to 1; its refractive power is 1:31, being the least so of any known substance that is not ačriform. See FREEZING and FREEzING Miature; and for the expansive power of water in . passing from its liquid state, see Evapor ATION and ExPANSION. Ice Cream, To make. Take a sufficient quantity of cream, and when it is to be mixed with raspberry or currant juice, a quarter part as much of the juice or jam, as of the cream. After beating and straining the mixture through a cloth, put it with a little juice of lemon into the mould, (a pewter vessel, and varying in size and shape at pleasure:) cover the mould, and place it in a pail about two-thirds full of ice, into which two handfuls of salt have been thrown, turn the mould by the hand-hold with a quick motion to and fro, in the manner used in milling chocolate, for 8 or 10 minutes; then let it rest as long, and turn it again for the same time ; and having left it to stand for half an hour, it is then fit to be turned out of the mould and set upon the table. Lemon juice and sugar, and the juices of various kinds of fruits are frozen without cream; and when cream is used, it should be well mixed. Ice. Boats. are so constructed as to sail upon ice, and they are common in Holland upon the Maese and lake Y. This figure represents one of these useful conveyances of goods I C E I C E. 501 DICTIONARY OF MECHANICAL SCIENCE. and passengers, whose breath is sometimes, however, affected bottom concave, to form a reservoir for the waste water till it by the rapid velocity at which this machine is driven. The simplest form of an ice house is the follow- Ice House. ing improvement upon the Italian and American plans:–In a soil where and springs do not strike above 16 feet deep, dig a pit 12 feet deep, and about 18 feet square. You may then erect a frame similar to the figure. The posts ought to be about 9 inches in diameter, placed near enough to each other for thin laths to be nailed upon them, and the inside dressed to an acute angle, so that as little wood as possible may touch the ice. On the inside let thin laths be nailed at about two feet apart; on the outside, at mo- derate distances, nail rough boards, and fill the place within with wheat or rye straw set on end. The in- side of the roof to be made in the same way, and also the gables. Straw to be sewed on the inside, and heath or straw on the outside of the door. The outside of the roof to be thatched thick with straw or heath; and heath, brushwood, or fir tops, to be filled in between the outside boarding and the sur- rounding ground, and then neatly thatched or turfed over. The bottom of the house, for 2 feet deep, to be laid with large logs or stones, next with heath, fir tops, or brushwood, and then with straw. The icehouse, when thus completed, will look like a square bee-hive inverted, and is then ready to receive the ice or snow Unless the house is in a very shady place, it may be necessary to extend the roof, where the door is placed, 5 or 6 feet, mak- ing a second gable and door, finished in the same way as the first, and fill up the intervening space, except a passage, with heath or straw. The best soil for an ice house to be made in is chalk, as it conveys away the waste water without any artificial drain; next to that, loose stony earth or gravelly soil. Its situation should be on the side of a hill, for the advantage of entering the cell upon a level, as in the drawing. To construct an ice house, first choose a proper place at a convenient distance from the dwelling-house, or house it is to serve; dig a cavity (if for one family, of the dimensions speci- fied in the design) of the figure of an inverted cone, sinking the -- can drain off: if the soil requires it, cut a drain to a consi- derable distance, or so far as will come out at the side of the º hill, or into a well, to make it communicate with the springs, and in that drain form a stink or air-trap, marked l, by sinking the drain so much lower in that place as it is high, and bring a partition from the top an inch or more into the water, which will consequently be in the trap, and will keep the well air- tight. Work up a sufficient number of brick piers to receive a cart wheel, to be laid with its convex side upwards to receive the ice; lay bundles of straw upon the wheel, which will let the melted ice drain through, and serve as a floor. The sides and dome of the cone are to be nine inches thick—the sides to be done in steened brickwork, i.e. without mortar, and wrought at right angles to the face of the work: the filling in behind should be with gravel, loose stones, or brickbats, that the water which drains through the sides may the more easily escape into the well. The doors of the ice house should be made as close as possible, and bundles of straw placed always before the inner door to keep out the air. Description of the parts referred to by the letters : —a, the line first dug out; b, the brick circum- ference of the cell; c, the diminution of the cell downwards; d, the lesser diameter of the cell; e, the cart wheel or joists and hurdles; f, the piers to receive the wheel or floor; g, the prin- cipal receptacle for straw; h, the inner passage; i, the first entrance; k, the out- er door, passages having a separate door each ; 1, an air trap, as in the upper figure; m, the well; m, the profile of the piers; o, the ice filled in; p, the height of the cone ; q, the dome worked in two half-brick arches; r, the arched passage; f, 6 M == = §§ 1 D I I co, Pigrion ARY OF MECHANICAL science dpºrtways inserted in the Walls; to the floor of the passage; §º: §. the #. may be put into the º: This must be covered, next the ...A. the dome, and then filled in with the earth.” ar, the sloping door, against which the straw should be laid., The ice, when to be put in, should be collected during the frost, broken into small pieces, and ram- med down hard in strata of not more than a foot, in order to make it one complete body; the care in putting it in, and well ramming it, tends much to its preservation. In a season when ice is not to be had in sufficient quantities, snow may be substituted. * Mode of filling the House.--When the ice, or snow, if ice cannot be procured, is put into the house, it must be well beaten down with a pavier's rammer, or mallet, and the surface always kept concave ; by this means any snow or ice that may melt will run to the middle, or interstices, and freeze. For the same reason, the surface of the ice ought always to be kept concave when ice is taken out for use. - Should the frost be very intense, when the ice house is get- ting filled, it may be very beneficial at the close of each day’s filling to throw in 30 or 40 pails full of water, which will fill the instertices and freeze. When the house is full, spread upon the concave surface a carpet, or sail, split up the middle, and put upon the top thereof a foot thick of straw. When ice is required for the use of the family, or when it is necessary to put in fresh meat to lie on the face of the ice for preservation, or to take out for use, the straw. and carpet, or sail, to be opened at the middle. - - Should rats infest the place, an iron wire frame or case may be required to put the meat or fish, &c. into, when lying on the ICC. *w A small open surface drain ought to be dug round the house, to prévent any water running into it. sº Opening the door of the house does little harm. Damp or dense substances touching the ice is much more prejudicial than dry air. t - ICH DIEN, a motto of the Prince of Wales's arms, signify- ing, in the High Dutch, “I serve.” The three ostrich feathers, and the motto Ich Dien, were worn by the king of Bohemia, slain by the Black Prince in the battle of Crecy, and were adopted as a memorial of the victory. ICHNOGRAPHY, in Perspective, the view of any thing cut off by a plane, parallel to the horizon, just at the base of the object. Among painters, it signifies the descriptions of images, or of ancient statues of marble, copper, or bronze, of busts and semi-busts, of paintings in fresco, mosaic works, and ancient pieces of miniature. Ich Nog RAPHY, in Architecture, is a transverse or horizontal section of a building, exhibiting the plot of the whole edifice, and of the several rooms or apartments in any story, together with the thickness of the walls and partitions, the dimensions of the doors, windows, chimney pieces, recesses, alcoves, the projections of all columns and piers, with every thing visible in such a section. ? ICHTHYOLOGY, that part of zöology which treats of fishes, their history, anatomy, physiology, and habitudes; and ; offers a systematic exposition of all the finny tribe. See ISHES. * ICONOCLASTS, in Church History, an appellation given to those persons who, in the 8th century, opposed image worship. ICOSAHEDRON, in Geometry, one of the regular platonic bodies, comprehended under twenty equal triangular sides or faces. Or, an icosahedron may be conceived to consist of twenty equal triangular pyramids, whose vertices or tops unite in one common point, which will be the centre of the circum- scribing sphere. ; : * To find the Surface and Solidity of an Icosahedron, the Side of one of its, equal Faces being given.—Let s represent the given Side; then will surface = 5 sº y 3 = 8*6602540352 - 7 + 3 M 5 ——=––= 2,1816950s, solidity = $s. The Radius of the Sphere circumscribing an Icosahedron being {:} to find its Side or Linear Edge, Surface, and Solidity.— et R répresent the given radius, then will id - = R. w 10 — *ze) Sl 6 © e º e º O & © tº e º º -º ( 5 surface . . . . . . . . 2 R3 (5 V 3 — M. 15) solidity # R* V (10 + 2 V 5) Or putting r to represent the radius of the inscribed sphdre, we shall have side............ = r V (42 – 18 M 5) surface ......... 27” (7 V3 – 3 M 15) 10 rs (7 V 3 – 3 M 16) solidity . . . . . . . . Or writing s for the side, we have e e 5 + V 5 radius circum. sphere = # sy (**** ) 9 @ ſº º Q º e º & 3 A/ 5 radius inscrib. sphere = 4s M (*****) IDES, in the Roman Calendar, were certain days in each month, which commenced on the fifteenth day of March, May, July, and October, but on the thirteenth in all the other months. The Romans had also the kalends and nones. The first day of the month was called kalenda; and the 7th of March, May, July, and October, was called the mona, ; but in all the other months of the year the 5th was calfed the mona. In reckoning they went back, as is shewn in the following table. A TABLE of the Kalends, Nones, and Ides. Days of April, June, January, March, the September, August, May, July, February. Month. November. December. October. . . 1 | Kalendae. Kalendae. Kalendae. Kalendae. 2 IV. A No- Iv. D No- VI. Y 2. 1v No- 3 III. } Ila S, III. } IlāS. V. S. I I I, § naS. 4 | Prid. Non. | Prid. Non. IV, ; Prid. Non. 5 Nonae. Nonae. III. D. " | Nonae. 6 VIII. VIII. Brid. Non. viii. 7 VII. VII. R - Nonae. W II, 8 v1. G. E. v1. Q & VIII. v1. V. E. 9 v. ( ; v. ( : VII. V. ( : 10 } W. 1 v. W. v1. Q - || 1 v. W. " 1l III, III. V. ; | II. 12 Prid. Id. Prid. Id. IV. W. " Drid. Id. 13 Idus. Idus. l il. Idus. 14 | xviii.) XIX. T Prid. Id. XVI. Y. 15 XVII. XVIII. Idus. XV. 16 XVI, XVI I. XVII.Y X I V. 17 XV, XVI. XVI. XIII, 18 XIV. XV. XV. XII. e.) 19 XIII. O XIV. , XIV. XI. 2. 20 XII. £. xiii. Sº XIII. . x. 3 21 xi. , ; XII. g XII. Q ix. ſ. 3. 22 x. ſº xi. S. E. xi. # viii. ? 23 IX. º X. I & X. 5. VII. 24 VI I.I. IX. IX. : VI. 25 VI.I. VIII. VIII. V. 26 VI, , VII. VII, IV. 27 V. VI, VI. IIſ. ...) 28 IV. W. . V, , , , Prid. Kal. 29 III. - IV. IV. Martii. 30. Prid. Kal. III. J III. J 31 || Mens. Seq. Prid. Kal. Prid, Kal. Mens. Seq. 1 Mens. Seq. IDENTITY, denotes that by which a thing is itself and not any thing else. . . . + - - IDIOM, among grammarians, properly signifies, the peouliar genius of each language, but is often used in a synonymous sense with, dialect. . . IDIOSYNCRASY, among physicians, denotes, a peculiar temperament of body, whereby it is rendered more liable to certain disorders than persons of a. different constitution usually are. IDIOTS, in Law. An idiot is a fool, or madman from his 1. L. E. I M A 503 DictionARY of MECHANICAL scIENCE. nativity. According to the statute of 17 Edward II. c. 9, the king shall have the custody of the lands of natural fools, taking the profits of them without waste or destruction, and shall find them necessaries. And after the death of them he shall render it to the right heir. But it seldom happens that a jury finds a man an idiot from his nativity, but only non compos mentis, from some particular time; in which case he comes under the denomination of a lunatic, of whose lands the king shall not have the profit, but is accountable for the same to the lunatic when he comes to his right mind, or to his executors or admi- nistrators. An idiot, or person non compos, may inherit and purchase; and if he marry and die, his wife shall be endowed. It is a general rule, that idiots and lunatics being incapable of judging between good and evil, are punishable by no criminal prosecution whatsoever. Acts solemnly acknowledged by them in a court of record, as fines and recoveries, and the uses de- clared on them, are good, and cannot be avoided by themselves or representatives. ... But during their lunacy, they are incapa- ble of making any will or testament, as are also persons grown childish from extreme old age. When an idiot sues or defends he must appear: but a lunatic shall appear by guardian or by attorney. IGNIS FATU Us, a common meteor, chiefly seen in -dark nights, frequenting meadows, marshes, and other moist places, and often seen in burying-grounds and near dunghils. It is known among the country-people by the appelation of Will with a Wisp and Jack with a Lantern. Sir Isaac Newton calls it a vapour shining without heat; and it has been supposed to be of the same nature with the light issuing from putrescent sub- stances. Willoughby and Ray were of opinion that it is occa- sioned by shining insects; but all the appearances of it ob- served by Dr. Derham, Beccaria, and others, sufficiently evince that it must be an ignited vapour. The form and size of the ignes fatui are very various and often variable. The late expe- riments on air serve to furnish a rational explication of this phe- nomenon, to which the ignorant and superstitious have ascribed so many alarming purposes. Inflammable air has been found to be the most common of all the factitious airs in nature, and to be the usual product of the putrefaction and decomposition of ve- getable substances in water; and Signior Volta, in a letter to Dr. Priestley, informs him that he fires inflammable air by the electric spark, even when the electricity is very moderate; and he supposes that this experiment explains the inflammation of the ignes fatwi, provided they consist of inflammable air issuing from marshy ground, by the help of the electricity, of fogs, and by falling stars, which are very probably thought to have an electrical origin. Dr. Shaw describes an ignis fatwus, which he saw in the Holy Land, that was sometimes globular, or in the form of the flame of a candle, and immediately afterwards spread itself so much as to involve the whole company in a pale inoffensive light, and then contract itself again, and suddenly disappear. But in less than a minute it would become visible as before ; or, running along from one place to another with a swift pro- gressive motion, would expand itself at certain intervals over more than two or three acres of the adjacent mountains. The atmosphere at this time had been thick and hazy; and the dew on their bridles was usually clammy and unctuous. At sea also, in similar weather, he observed those electrical luminous appearances skip about the masts and yards of ships, and which may also frequently be seen playing at night on the arms of soldiers encamped in low grounds. IGNITION, the application of fire to metals, till they become red-hot without melting. Ignition takes place in gold, silver, and iron; but lead and tin melt before they are red-hot. ILEX, im Botany, holly, a genus of the tetrandria tetragynia class and order.—Natural order of Dumosae. Rhamni, Jussieu. There are sixteen species. This genus consists of small trees, shrubs with alternate leaves, evergreen, toothed, or thorny; and axillary, many-flowered peduncles. I.Aquifolium, common holly, is usually from twenty to thirty feetin height, though it sometimes exceeds sixty feet. The holly makes an impenetrable fence, and bears cropping well, nor does its verdure suffer from the severest of our winters. woods. Sheep and deer are fed during the winter with the croppings. Birds eat the berries.—The bark fermented and The wood is the whitest of all hard afterwards washed from the woody fibres, makes the common birdlime. ILIAC PAssion, a violent dangerous kind of cholic; called also valvulus, miserere mei, and chordapsus. It takes its name from the intestine ilion, on account of its being usually affected in this distemper; or perhaps from the Greek verb etxeiv, “to wind or twist;” whence also the Latins call it valvulus. ILLECEBRUM, a genus of plants belonging to the pentan- dria class, and, in the natural method ranking under the 12th holoraceae. +. - ". ILLICIUM, a genus of plants belonging to the decandria class; and in the natural method ranking with those of which the order is doubtful. - - ILLUMINATING, a kind of miniature painting, anciently much practised for illustrating and adorning books. Besides the writers of books, there were artists whose profession was to ornament and paint manuscripts, who were called illumina- tors; the writers of books first finished their part, and the illuminators embellished them with ornamented letters and paintings. We frequently find blanks left in manuscripts for the illuminators, which were never filled up. Some of the ancient manuscripts are gilt and burnished in a style superior to later times. Their colours were excellent, and their skill in preparing them must have been very great. . ILLUMINATION, that which results from, or the effect of, a luminous body. * IMAGE, in Optics, is the appearance of an object made either by reflection or refraction. See LENs, MIRROR, Reflec- TION, and REFRACTION. IMAGE, in a religious sense, is an artificial representation or similitude of some person or thing, used either by way of decoration and ornament, or as an object of religious worship and adoration; in which last sense it is used indifferently with the word Idol. The noble Romans preserved the images of their ancestors with a great deal of care and concern, and had them carried in procession at their funerals and triumphs; these were commonly made of wax, or wood, though sometimes of marble or brass. They placed them in the vestibule of their houses; and they were to stay there, even if the houses hap- pened to be sold, it being accounted impious to displace them. IMAGE, in Rhetoric, also signifies a lively description of any thing in discourse. IMAGEs, in discourse, are defined by Longinus to be, in gene- ral, any thoughts proper to produce expressions, and which present a kind of picture to the mind. But in the more limited sense, he says, images are such discourses as come from us, when, by a kind of enthusiasm, or an extraordinary emotion of the soul, we present them before the eyes of those who hear us. IMAGes, in Rhetoric, have a very different use from what they have among the poets; the end principally proposed in poetry is, astonishment and surprise; whereas the thing chiefly aimed at in prose, is to paint things naturally, and to shew them clearly. They have this, however, in common, that they both tend to move, each in its kind. * Q These Images or Pictures are of vast use to give weight, mag- nificence, and strength, to a discourse. They warm, and ani- mate it; and when managed with art, according to Longinus, seem, as it were, to tame and subdue the hearer, and put him in the power of the speaker. º tº . A IMAGINARY QUANTITIES, or Impossible Quantities, in Alge- bra, are certain expressions that arise in various algebraical and trigonometrical operations, to which no value either ra- tional or irrational can be assigned, yet being substituted in the equation whence they were deduced, they are found to answer | the condition of the question. IMAGINATION, a power or faculty of the mind, whereby it conceives and forms ideas of things communicated to it by the outward organs of sense. Though the fancy and the imagina- tion are nearly allied, yet these faculties are distinct. t IMAM, or IMAN, a minister in the Mahometan church, answering to a parish priest among us. The word, properly signifies waat we call a prelate, antistes, one who presides over others; but the Mussulmen frequently apply it to a person who has the care and intendancy of a mosque, who is always first there, and reads prayers to the , people, which they repeat after him. Imam is also applied, by way of excellence, 504 I M P I M P DICTIONARY OF MECHANICAL SCIENCE. to the four chiefs or founders of the four principal sects in the Mahometan religion. Thus, Ali is the Imam of the Persians, or of the sect of the Schiates; Abu-beker the Imam of the Sunites, which is the sect followed by the Turks; Saphii or Saf-y, the Imam of another sect, &c. IMBECILITY, a languid infirm state of the body, which being greatly impaired, is not able to perform its usual exer- cises and functions. IMBEZZLE, signifies to steal or secrete goods, &c. intrusted to a person's charge. Servants, embezzling their masters’ goods to the value of 40s, are guilty of felony, and subject to transportation. IMBIBING, the action of a dry porous body, that absorbs or takes up a moist or fluid one: thus sugar imbibes water; a sponge, the moisture of the air, &c. - IMBRICATED, is used by some botanists, to express the figure of the leaves of some plants which are hollowed like an imbrea, or gutter-tile, or are laid in close series over one another like the tiles of a house. IMITATION, derived from the Latin imitare, “to repre- sent or repeat,” a sound or action, either exactly or nearly in the same manner as they were originally exhibited. IMITAtion, in Music, admits of two different senses; sound and motion are either capable of imitating themselves by a repetition of their own particular modes, or of imitating other objects of a nobler and more abstracted nature. IMITATION, in Oratory, is an endeavour to resemble a speaker or writer, in those qualities with regard to which we propose them to ourselves as patterns. The first historians among the Romans, says Cicero, were very dry and jejune, till they began to imitate the Greeks, and then they became their rivals. It is well known how closely Virgil has imitated Homer in his AEneid, Hesiod in his Georgics, and Theocri- tus in his Eclogues. Terrence copied after Menander; and Plautus after Epicarmus, as we learn from Horace, lib. ii. ad Augus. who himself owes many of his beauties to the Greek lyric poets. Cicero appears, from many passages in his writings, to have imitated the Greek orators. Thus Quin- tilian says of him, that he has expressed the strength and sub- limity of Demosthenes, the copiousness of Plato, and the delicacy of Socrates. IMITATIVE, in Music, a term applicable to that music which is composed in imitation of the effects of some of the operations of nature, art, or human passion. IMMATERIAL, something devoid of matter, or that is pure spirit. IMMEMORIAL, in Law, an epithet given to the time or du- ration of any thing whose beginning we know nothing of. In a legal sense, a thing is said to be of time immemorial, that was before the time of King Edward II. IMMENSITY, an unlimited extension, or which no finite and determinate space, repeated ever so often, can equal. IMMERSION, in Astronomy, is when a planet, comet, or other heavenly body approaches so near to conjunction with the sun, that it is enveloped in his rays, and lost to our observation. Immersion also denotes the beginning of an eclipse, or of an occultation, when the body or any oart first begin to disappear, either behind another body or in its shadow ; as in an eclipse of the sun, when the disc is first covered by the edge of the moon; or as in an eclipse of the latter body, when she first enters the terrestrial shadow. IMMUTABILITY, one of the divine attributes. The immu- tability of God is two-fold, physical and moral. The first con- sists in this, that the divine essence does not, nor possibly can, receive any alteration ; and the moral immutability is founded on the perfection of his nature, whereby he always wills the same things, or such as are best on the whole. IMPALPABLE, that whose parts are so extremely minute that they cannot be distinguished by the senses, particularly by that of feeling. IMPANNELING, in Law, signifies the writing down or entering into parchment list, or schedule, the names of a jury summoned by the sheriff to appear for such public services as juries are employed in. IMPARLANCE, in Law, a petition in court for a day to consider or advise what answer the defendant shall make to the plaintiff's action, and is the continuance of the cause till another day, or a longer time given by the court. - IMPASSIBLE, that which is exempt from suffering; or which cannot undergo pain or alteration. The Stoics place the souls of their wise men in an impassible, imperturbable state. IMPASTATION, the mixture of various materials of differ- ent colours and consistencies, baked or bound together with some cement, and hardened either by the air or by fire. IMPATIENS, Touch-me-not, and Balsamine, a genus of plants belonging to the syngenesia class; and in the natural method ranking under the 24th order, corydales. IMPEACHMENT, an accusation and prosecution for trea- son, and other crimes and misdemeanours. Any member of the lower house of parliament may impeach any one belonging either to that body or to the house of lords. The method of proceeding is to exhibit articles on the behalf of the commons, by whom managers are appointed to make good their charge. These articles are carried to the lords, by whom every person inpeached by, the commons is always tried; and if they find him guilty, no pardon under the great seal can be pleaded to such an impeachment, 12 William III. cap. 2. The most cele brated impeachment in our own times was that of the late Warren Hastings. • IMPEACHMENT of W Aste, signifies a restraint from com- mitting of a waste upon lands and tenements IMPEDIMENTS, in Law, are such hinderances as put a stop or stay to a person seeking for his right by due course of law. Persons under impediments, are those under age or coverture, non compos mentis, in prison, beyond the sea, &c. &c. who, by a saving in our laws, have time to claim and prose- cute their rights, after the impediments are removed, in case of fines levied, &c. IMPENETRABILITY, forms a discriminating feature of body. This principle is commonly regarded as an axiom, but it is a truth derived from early and invariable experience. It rests on the incontrovertible fact, that no two bodies can occupy the same space in the same precise instant of time. Had the case indeed been otherwise, each body might be successively ab- sorbed into the substance of another, till the whole frame of the universe, collapsing into a point, were lost in the vortex of annihilation. But although the most palpable observation sufficiently attests the impossibility of the mutual compenetra- tion of bodies, yet this property may be farther illustrated and confirmed by a few simple experiments. 1. A vessel being fill- ed to the brim with water, if any solid incapable of dissolving in that liquid, be plunged in it, a portion of the water will over- flow, exactly equal to the bulk of the wood or metal immersed. 2. If a cylinder be gradually pressed downwards into a glass cylinder partly filled with water, the liquid will rise proportion- ally, till the space passed over by its surface shall be equal to the portion of the cylinder introduced. These two experi- ments shew that water opposes the entrance of a solid sub- stance, and retires on all sides to give room for its advance. Simple as the fact appears, it was first distinctly noticed by Archimedes, who made it the ground of his hydrostatical theory. The same truth is evinced by other experiments. 3. If a cork be rammed hard into the neck of a phial filled with water, the phial will burst, while its neck remains entire. 4. Bladders filled with water, and disposed upon a table, will support very large weights placed on a board which has been laid over them. 5. The same experiment will equally succeed with bladders blown full of air. 6. The disposition of the air to resist all penetration is made conspicuous in another way. Let a large and very tall glass vessel be nearly filled with water, on the surface of which a lighted taper is set to float ; if, over this glass, a smaller cylindrical vessel, likewise of glass, be inverted and pressed downwards, the contained air maintaining its place, the internal body of the water will descend, while the rest will rise up at the sides, and the taper will appear for some seconds to burn, encompassed by the whole mass of liquid. IMPERATIVE, one of the moods of a verb, used when we would command, entreat, or advise. IMPERFECT, something that is defective, or that wants some of the properties found in other beings of the same kind: thus mosses are called imperfect plants, because almost all the parts of fructification are wanting in them. ... I M P I M P DICTIONARY OF MECHANICAL SCIENCE. 505 IMPERF ect Numbers, such whose aliquot parts taken together do either exceed or fall short of that whole number of which they are parts; they are either abundant or deficient. IMPETIGENES, in Medicine, descriptive of those disorders which, from a general had habit, manifest themselves principal- ly by disfiguring the skin and external parts of the body. IMPETUS, in Mechanics, the force with which one body im- pels or strikes another. IMPLEAD, to sue or prosecute by course of law. IMPLICATION, in Law, is when something is implied that is not expressed by the parties themselves in their deeds, con- tracts, or agreements. IMPLY, To, or CARRY, in Music. These we have used as synonymous terms in that article. They are intended to sig- nify those sounds which ought to be the proper concomitants of any note, whether by its own nature, or by its position in artificial harmony. Thus every note, considered as an inde- pendent sound, may be said to carry or imply its natural har- monies, that is to say, its octave, its twelfth, and its seven- teenth; or, when reduced, its eighth, its fifth, and its third. But the same sound, when considered as constituting any part of harmony, is subjected to other laws and different limitations. It can only be said to carry or imply such simple sounds, or complication of sound, as the preceding and subsequent chords admit or require. For these the laws of melody and harmony must be consulted. See MELoDY and HARMONY. - IMPONDERABLE SUBSTANces, are light heat, and electri- city, which have no sensible weight. IMPORTATION, the act of bringing goods into a country from foreign parts. It has generally been considered, that for any country to carry on a profitable trade, it is necessary that the value of the goods sent out of it should be greater than that of the articles imported; this, however, is a very eroneous axiom, unless it is understood with great limitations. All arti- cles of merchandise imported merely for re-exportation, and also such as are used or worked up in our own manufactures, are far from being hurtful to our commerce, and may even, in many respects, be deemed of equal profit with our own native commodities. It is therefore an excess of such importations alone, as are either for mere luxury or mere necessity, or for both together, which is disadvantageous to the country. IMPOST, in Architecture, a capital or plinth to a pillar or pilaster, or pier that supports an arch, &c. IMPost, in Law, signifies, in general, a tribute or custom, but is more particularly applied to signify that tax which the i. receives for merchandises imported into any port or a VCI), IMPOSTHUME, or ABscess, a collection of matter or pus in any part of the body, either owing to an obstruction of the fluids in that part, which makes them change into such matter, Or a fanslation of it from some other part, where it was gene- rated. IMPOSTOR, in a general sense, denotes a person who cheats by a fictitious character. - IMPOSTORs, Religious, are such as falsely pretend te an extraordinary commission from heaven, and who terrify and abuse the people with false denunciations of judgments. These are punishable in the temporal court with fine, imprisonment, and infamous corporal punishment. IMPOTENCE, or IMPotency, in general, denotes want of strength, power, or means to perform any thing. Divines and philosophers distinguish two sorts of impotency; natural and moral. The first is a want of some physical principle, neces- sary to an action; or where a being is absolutely defective, or not free and at liberty to act: the second only imports a great iºlº ; as a strong habit to the contrary, violent passion, or € IIKe. - IMPRECATION, (derived from im and precor, “I pray,”) a curse, or wish that some evil may iſſ any one. The ancients had their goddesses called imprecations, in Latin Dirae, i. e. Deorum ira, who were supposed to be the execu- tioners of evil consciences. They were called Dirae in heaven, Furies on earth, and Eumenides in hell. The Romans owned but three of these imprecations, and the Greeks only two. They invoked them with prayers and pieces of verses, to destroy l their enemies. IMPREGNATION, the state of a female being with young. See Conception. The term impregnation is also used in Pharmacy, for communicating the virtues of one medicine to another, whether by mixture, coction, digestion, &c. IMPRESSING SEAMen. The power of impressing sea- faring men for the sea service by the king's commission, has been a matter of some dispute, and submitted to with great reluctance; though it has very clearly and learnedly been shewn by Sir Michael Forster, that the practice of impressing, and granting powers to the admiralty for that purpose, is of a very ancient date, and has been uniformly continued by a regular series of precedents to the present time: whence he concludes it to be part of the common law. The difficulty arises from hence, that no statute has expressly declared this power to be in the crown, though many of them very strongly imply it. The statute 2 Rich. II. c. 4. Speaks of mariners being arrested and retained for the king's service, as of a thing well known, and practised without dispute; and provides the remedy against the running away. By a later statute, if any water- man, who uses the Thames, shall hide himself during the exe- cution of any commission of pressing for the king's service, he is liable to heavy penalties. By another, (5 Eliz. c. 5.) no fisherman shall be taken by the queen’s commission to serve as a mariner; but the commission shall be brought first to two justices of the peace inhabiting near the sea-coast, where the mariners are to be taken, to the intent that the justices may choose out and return such a number of able-bodied men, as in the commission are contained, to serve her majesty. And by others, especial protections are allowed to seamen in particular circumstances, to prevent them from being impressed. Ferry- men are also said to be privileged from being impressed, at common law. All which do most evidently imply a power of impressing to reside somewhere; and if any where, it must, from the spirit of our constitution, as well as from the frequent men- tion of the king's commission, reside in the crown alone. After all, however, this method of manning the navy is to be con- sidered as only defensible from public necessity, to which all private consideration must give way. The following persons are exempted from being impressed:—Apprentices for three years; the master, mate, carpenter, and one men for every 100 tons, of vessels employed in the coal trade; all under 18 years of age, and above 55; foreigners in merchant ships and pri- vateers; landmen betaking themselves to sea for two years; seamen in the Greenland fishery, and harpooners, employed, during the interval of the fishing season, in the coal trade, and giving security to go to the fishing next season. - IMPRESSION, is applied to a species of objects which are supposed to make some mark or impression on the senses, the mind, and the memory. The Peripatetics assert, that bodies emit species resembling them, which are conveyed to the com- mon senserium, and they are rendered intelligible by the active intellect; and when thus spiritualized, are called expressions, or express species, as being expressed from the others. IMPRession, also denotes the edition of a book, regarding the mechanical part only; whereas, besides this, it takes the care of the editor, who corrected or augmented the copy, add- ing notes, &c. to render the work more useful. IMPRISONMENT, the state of a person restrained of his liberty, and detained under the custody of another. No per- son is to be imprisoned but as the law directs, either by the command or order of a court of record, or by lawful warrant; or the king's process, on which one may be lawfully detained. And at common law, a person could not be imprisoned unless he were guilty of some force and violence, for which his body was subject to imprisonment, as one of the highest executions. Where the law gives power to imprison, in such cases it is justifiable, provided he that does it in pursuance of a statute, exactly pursues the statute in the manner of doing it; for otherwise it will be deemed false imprisonment, and of conse- quence it is unjustifiable. Every warrant of commitment for imprisonment ought to run, “till delivered by due course of law,” and “not until further order;” which has been held ill: and thus it also is, where one is imprisoned on a warrant not mentioning any cause for which he is committed. But an act of this kind can rarely occur in Britain. . . . the person is False IMPRIsonMent. Every confinement of 6 N 506 I N C I N C DICTIONARY OF MECHANICAL SCIENCE. an imprisonment, whether it be in common prison, or in a pri- vate house, or in the stocks, or even by forcibly detaining one in the public streets. Unlawful or false imprisonment, consists in such confinement or detention without sufficient authority: which authority may arise either from some process from the courts of justice; or from some warrant from a legal power to commit, under his hand and seal, and expressing the cause of such commitment; or from some other special cause warranted, for the necessity of the thing, either by common law or act of parliament; such as the arresting of a felon by a private per- son without warrant, the impressing of mariners for the public service, or the apprehending of waggoners for misbehaviour in the public highways. False imprisonment also may arise by executing a lawful warrant or process at an unlawful time, as on a Sunday; or in a place privileged from arrests, as in the verge of the king's court. This is the injury. The remedy is of two sorts, the one removing the injury, the other making satisfaction for it. The satisfactory remedy for this injury of false imprisonment, which is generally and almost unavoid- ably accompanied with a charge of assault and battery also, is, that the party therein shall recover damages for the injuries he has received; and also the defendant is, as for all other injuries committed with force, or vi et armis, liable to pay a fine to the king for the violation of the public peace. - IMPROPRIATION, is when a benefice ecclesiastical is in the hands of a layman, and Appropriation when in the hands of a bishop, college, or religious house. It is said there are 3845 impropriations in England. IMPULSE, a momentary action, or force, such as that which arises from the sudden explosion of fired gunpowder, or the momentum of a moving body. IMPULSION, in Mechanical philosophy, a term employed for expressing a supposed peculiar exertion of the powers of body, by which a moving body changes the motion of another body by hitting or striking it. The plainest case of this action is, when a body in motion hits another body at rest, and puts it in motion by the stroke. The body thus put in motion is said to be impelled by the other; and this way of producing motion is called impulsion, to distinguish it from pression, pushing, or protrusion, by which we push a body from its place without striking it. The term has been graduaily extended to every change of motion occasioned by the collision of bodies. See MechA Nics. IMPULSIVE, relating to impulse. IMPUTATION, in general, the charging something to the account of one which belonged to another; thus the assertors of original sin maintain, that Adam's sin is imputed to all his posterity. In the same sense, the righteousness and merits of Christ are imputed to true believers. e INACCESSIBLE, that which cannot be approached; thus we say inaccessible height, distance, &c. See ACCESSIBLE Height and DistANCE. INALIENABLE, that which cannot be legally alienated or made over to another: thus the dominions of the king, the revenues of the church, the estates of a minor, &c. are inalien- able, otherwise than with a reserve of the right of redemption. IN ARCHING, in Gardening, a method of grafting, usually called grafting by approach. INAUGURATION, the coronation of an emperor or king, or the consecration of a prelate ; so called from the ceremonies used by the Romans, when they were received into the college of augurs. * IN AUTRE DROIT, in another's right, is where executors or administrators sue for debt or duty, &c. of the testator or intestate. INCANTATION, denotes certain ceremonies, accompanied with a formula of words, and supposed to be capable of raising devils, spirits, &c. See CHARM, &c. INCAPACITY, in the Canon law, is of two kinds. I. The want of dispensation for age in a minor, for legitimation in a bastard, and the like: this renders the provision of a benefice void in its original. 2. Crimes and heinous offences, which annul provisions at first valid. INCARNATION, in Theology, denotes the act whereby the Son of God assumed the human nature; or the mystery by which Jesus Christ, the eternal Word, was made man, in order . to accomplish the work of our salvation. The era used among Christians, whence they number their years, is the time of the incarnation, that is, of Christ's conception in the virgin's womb. INCENDIARY, in Law, is applied to one who is guilty of maliciously setting fire to another's dwelling-house; and all houses that are parcel thereof, though not contiguous to it, or under the same roof, as barns and stables. A bare intent or attempt to do this, by actually setting fire to a house, unless it absolutely burns, does not fall within the description of incendit et consumpsit. But the burning and consuming of any part is sufficient, though the fire be afterwards extinguished. It must also be a malicious burning; otherwise it is only a trespass. This offence is called arson in our law. INCENSE, or FRANKINCENse, in the Materia Medica, &c. a dry resinous substance, known among authors by the names thus and olibanum. Incense is a rich odour, with which the Pagans and the Roman Catholics still perfume their temples altars, &c. The words come from the Latin incensum, q. d. burnt; as taking the effect for the thing itself. The burning of incense made part of the daily service of the ancient Jewish church. The priests drew lots to know who should offer it; the destined person took a large silver dish, in which was a censer full of incense; and being accompanied by another priest carrying some live coals from the altar, went into the temple. There, in order to give notice to the people, they struck upon an instrument of brass, placed between the temple and the altar; and being returned to the altar, he who brought the fire to the altar left it there, and went away. Then the offerer of incense having said a prayer or two, waited the signal, which was the burning of the holocaust; in mediately upon which he set ſire to the incense, the whole multitude continuing all the time in prayer. The quantity of incense offered each day was half a pound in the morning, and as much at night. The reason of this continual burning of incense might be, that the multitude of victims that were continually offered up, would have made the temple smell like a slaughter-house, and consequently have inspired the comers rather with disgust and aversion, than awe and reverence, had it not been overpowered by the agreeable fragrance of those perfumes. INCEST, is the carnal knowledge of persons within the Levi- tical degrees of kindred. INCH, a measure of length; being the 12th part of a foot, and equal to three barleycorns in length. INC. PHASING. See ENCHAS ING. INCIDENCE, in Mechanics and Optics, is used to denote the direction in which a body or ray of light strikes another body, and is otherwise called inclination. In moving bodies, their incidence is said to be perpendicular or oblique, according as their lines of motion make a straight line or an angle at the point of contact. - * Angle of INCIDENCE, generally denotes the angle formed by the line of incidence and a line drawn from the point of contact perpendicular to the plane or surface on which the BI body or ray impinges. Thus if a body A impignes on the plane D E, at the A O point B, and the perpendicular B H be drawn, then the angle A B H is ge- nerally called the angle of incidence, and A B D the angle of inclination. D —F. Dr. Wallis, however, and some other B old authors, call the angle A B D the angle of incidence, being that included between the line of inci- dence, and the surfaces of the plane on which the body im- pinges; the complement of that angle, as A B H, being by these writers called the angle of inclination. Other distinctions are made by Wolfius in the denomination of these angles, but they are of very trifling importance. 1. It is demonstrated by writers on optics, that the angle of incidence A B H, is always equal to the angle of reflectio H B C ; or the angle A B D = angle C B E. See REFLECTION. 2. It has also been demonstrated from experiment, that the angles of incidence and refraction are to each other, accurately or very nearly, in a given ratio. , 3. That from air to glass the sine of the angle of incidence is to the sine of the refracted angle, as 300 to 193, or nearly as 14 to 9; and on the contrary, I N C I N C 50/. DICTIONARY OF MECHANICAL SCIENCE, from glass to air, the angle of incidence to that of refraction, is as 193 to 300, or nearly as 9 to 14. See REFRACTION. Aa is of INCIDENCE, is the line B H in the preceding figure. |Line of INCI pence, or INCIDENT Ray, in Catoptrics, and Di- optrics, is the line of direction in which a ray is propagated, as the line A B, in the above figure; this is also called the INCI- oeNT Ray. - Point of INCIDENce, is the point where the incident ray meets the reflecting or refracting body; such is the point B. INCIDENT, signifies a 'thing necessarily depending upon another as more principal. INCLINATION, denotes the mutual approach or tendency, of two bodies, lines, or planes, towards each other, so that the lines of their direction make. at the point of contact any angle of greater or less magnitude. INCLINAT to N of a Right Line to a Plane, is the acute angle which such a right line makes with another right line, drawn in the plane through the point where the inclined line intersects it, and through the point, where it is also cut by a perpendi- cular drawn from any point of the inclined lines. INCLINATION of Meridians, in Dialling, the angle that the hour line on the globe, which is perpendicular to the dial plane, makes with the meridian. INCLINATION of an Incident Ray, otherwise called the angle of INclin Ation. See Angle of INCIDENCE. INCLINATION of a Reflected Ray, is the angle which a ray after refraction makes with the axis of inclination. INCLINAT.1on of the Aacis of the Earth, is the angle which it makes with the plane of the ecliptic; or the angle between the planes of the equator and ecliptic. INCLINATION of the Magnetic Needle. See DIPPING Needle. INCLINATION of a Planet, is an arc or angle comprehended between the ecliptic, and the plane of a planet in its orbit. INCLINATION of a Plane, in Dialling, is the arc of a vertical circle perpendicular both to the plane and to the horizon, and intercepted between them. - INCLINAT 1 on of two Plames, is the acute angle made by two lines drawn one in each plane, through a common point of sec- tion, and perpendicular to the same common section. INCLINAT to N, Angle of, in Optics, is the same that is other- wise called the angle of INCIDENCE. INCLINED PLANE, in Mechanics, as the name imports, is a plane which forms with an horizontal plane any angle whatever, forming one of the simple mechanical powers. The inclination of the plane is measured by the angle formed by two lines drawn from the sloping and the horizontal plane, perpendicular to their common intersection. The principal mechanical pro- perties of the inclined plane are as follows; viz. 1. When a body is sustained upon an inclined plane, the sustaining power, or weight, will be to the weight of the body, as the sine of the plane’s inclination is to the sine of the angle which the direction of the power makes with a perpendicular to the plane. Thus, let A B be an inclined plane, W a weight sustained upon that plane by the power, WF the line of the direc- tion of the power, and WC a perpendi- cular to the plane A B : then P: W : : sine Z. A B C sine / F W C. When W F coincides with WA, that is, when the power acts in a direction pa- rallel to B.A., then the proportion be- comes P: W :: sine of plane's incli- B - nation : radius; or, which is the same thing, P: W :: A C : JB A ; that is, the power : weight :: height of the plane : its length. When a plane is inclined to the horizon one-third of its whole length, any body will be kept from rolling down that plane, by a power equal to a third part of the weight of the body. If D A be six feet and B D two feet: then if C be six pounds, a power fo two pounds will support it: if the height of the plane be equal to half its length, a power equal to half the weight of the body will support it: but a plane perpendicularly situated, ought not to come under the denomination of this article, because the plane in such a direction contributes nothing to the support or hinderance of the falling body, which D descendswith its whole force of gravity, unless prevented by a power equal to its whole weight. It is obvious from this illustration, that the less the A. B angle of elevation, or the - gentler the ascent is, the greater will be the weight which a given power can draw up; for the steeper the inclined plane is, the less does it support of the weight; and the greater the tendency which the weight has to roll, consequently the more difficult for the power to support it : hence the advantage gained by this mechanical power is as great as its length (AD) exceeds its perpendicular height (BD). 2. If two bodies keep each other in equilibrio, by a string passing over the vertex of two different inclined planes, the weights of the bodies will be to each other as the sines of the angles of inclination of the opposite planes. That is, W: P :: sine Z. B C A : sine Z. A B C ; A. Or W: P :: B A : A C ; because the sides of triangles are to each other as the sines of their oppo- site angles. The velocity acquired by a body de- scending by the action of gravity down an inclined plane, is to the velocity of a body falling perpendicularly during the same time, as the height of the plane is to the length. The force whereby a body descends down an inclined plane is to the absolute force of gravity, as the height of the plane to its length; which being a constant ratio for the same plane, it follows that the force whereby the body descends is uniform, and consequently that it will produce a uniformly accelerated motion. Therefore all the laws laid down under the article ACCELERATION have equal place with regard to bodies on in- clined planes, by merely substituting for gravity the product of gravity into the sine of the plane's inclination. The same is also true with regard to the retardation in bodies projected up any given inclined planes. 3. Hence again the space descended down inclined planes is to the space perpendicularly described in the same time, as the height of the plane is to its length. - Consequently the velocities acquired, B and the spaces descended by bodies down different inclined planes in the D same time, are as the sines of the plane's N elevation. If A B be any inclined plane, and D C be drawn perpendicular to A B ; then A C while a body falls freely through the per- pendicular B C, another body will in the same time descend down the part of the plane B D. T3 Hence we deduce the following curious property of bodies descending down inclined D planes. In any right-angled triangle having its hypothen use B C perpendicular to the horizon, a body will descend down any of its three sides, B D, B C, DC, in the same time. And therefore, if on the diameter B C a semi- circle be described, the time of descending TX down any chords BD, BD, BD”, &c. DC, C’ D'C, D" C, &c. will be all equal, and each equal to the time of falling freely through the diameter B C. The time of descending down an inclined plane, is to the time in falling through its perpendicular height, as the length of the plane is to its height. Consequently the times of de- scending down different planes of the same height are as the lengths of the planes. A body acquires the same velocity in descending down an inclined plane, as in falling perpendicularly through the height of the plane. Hence the velocities are always the same in pianes of the same altitude, whatever may be their degrees of nclination. We may form an inclined plane by placing boards of earth or other materials in a sloping direction. The sides of hills, 508 1 N D I N C DICTIONARY OF MECHANICAL SCIENCE. wedges, screws, jacks, &c. are all used in mechanics on the same principle; and their power depends on the proportion between the height actually attained, and the length of the plane moved oyer. INCLINERS, or INCLINING DIALs, are such as are drawn on planes that are not perpendicular to the horizon. INCLOSURES. Any person who shall wilfully or malici- ously destroy or damage any fence made for enclosing any common waste, or other lands, in pursuance of any act of par- liment, shall be transported for seven years. INCOMBUSTIBLE Cloth. See Asbestos. On this, Cron- stadt observes, that the natural stone of the asbesti is in pro- portion to their economical use, both being very inconsiderable. It is an old tradition, that in former ages they made clothes of the fibrous asbesti, which is said to be composed of the word byssus ; but it is not very probable, since, if one may conclude from some trifles now made of it, as bags, ribbons, and other things, such a dress could neither have an agreeable appear- ance, nor be of any conveniency or advantage. It is more probable, that the Scythians dressed their dead bodies which were to be burned, in a cloth manufactured of this stone; and this perhaps has occasioned the above fable. Mr. Magellan confirms this opinion of Cronstadt's, and informs us, that some of the Romans also enclosed dead bodies in cloth of this kind. In the year 1756 or 1757, he tells us, that he saw a large piece of asbestos cloth found in a stone tomb, with the ashes of a Roman, as appeared by, the epitaph. It was kept with the tomb also, if our author remembers rightly, in the right wing of the Vatican library at Rome. The under librarian, in praer to shew that it was incombustible, lighted a candle, and let some drops of wax fall on the cloth, which he set on fire with a candle in his presence, without any detriment to the cloth. Its texture was coarse, but much softer than he could have expected. There are many substances of vegetable origin, of common domestic use, which it would be of the utmost importance to render less liable to be set on fire, if they could not be rendered incombustible altogether. If muslips, and other cotton goods, be dipped in a weak solution of potass, they will be less liable to burn; but the objection is, that by the attraction of moisture from the atmosphere, they would be less agreeable. It has also been found, that solutions of muriate, sulphate, phosphate, and borate of ammonia, with borax, render cloth incombustible. Acidulous phosphate of lime has the same effect. Linen, mus- lin, wood, or paper, dipped in a solution of this salt, of the specific gravity of 1:26 to 1:30, are completely incombustible and may be charred by intense heat, but will not burn. Seve- ral experiments were made at Venice in 1807, by a Monsieur Gonzatti, with a liquor, which being thrown in a small quantity on any combustible article on fire, has immediately extinguish- ed it. A few drops only, being thrown on a quantity of resin and oil, which was burning, the fire was immediately extin- guished; and it was said that a layer of this composition being spread upon any wood work, it was entirely safe from combus- tion. The inventor would not make known the preparation of his composition, but it was very probably a solution of alum, potass, and vitriol. IN COMMENSURABLE LINEs, are such as have no com- mon measure. The diagonal and side of a square are incommen- surable, being to each other as V 2 to l ; and consequently whatever number of parts the side of the square may be divided into, the hypothenuse will not be made up of any exact number of such parts. INCOMMENSURABLE Numbers, or Numbers Prime to each other, are those which have no integral common measure greater than unity. If numbers be incommensurable with each other, they are incommensurable also in power, that is, no powers of such numbers can be incommensurable with each other. INCOMPLETE, in Botany, a term used to denote the six- teenth class of the Linnaean “methodus calycina,” consisting of plants whose flowers want either the calyx or petals. INCOMPOSITE NUMBERs, the same as PRiMe Numbers. INCORPORATION, Power of. To the erection of any cor- poration the king's consent is necessary, either impliedly or expressly given. The methods by which the king's consent is expressly given to the formation of a body politic, are either by act of parliament or charter. INCREMENT, in the doctrine of Increments, or Finite Dif- ferences, is the finite increase of a variable quantity. Dr. Brooke Taylor, to whom we are indebted for this theory, denoted his, increments by a dot under the variable quantity: thus the incre- ment of a was denoted by a ; Emmerson also employs the same notation ; others have used a small accent, as a ', or thus ar. —Mr. Nicole denotes the increment of a., or any variable, ' by n; but Euler, who seems to have given a permanent form to this branch of analysis, employs the character A a ; thus the increment of a = A a, increment of y = A y, &c. INCUBUS, Nightmare, a disease consisting in an oppres- sion of the breast so very violent, that the patient cannot speak or even breathe. The word is derived from the Latin incubare, to “lie down” on any thing and press it. The Greeks call it sporaMng, q, d. Saltator, “leaper,” or one that rusheth on a per- son. In this disease the senses are not quite lost, but drowned and astonished, as is the understanding and imagination, so that the patient seems to think some huge weight thrown on him ready to strangle him. Children are very liable to this distemper; so are fat people, and men of much study and application of mind—because the stomach, in all these, finds some difficulty in digestion. INCUMBENT, a clerk or minister who is resident on his benefice; he is called incumbent, because he does, or at least ...” bend his whoke study to discharge the cure of his church. INCURVATION of the RAYs of LIGHT, their bending out of the rectilinear or straight course, occasioned by refraction. INDEFINITE, that which is without any assigned limits; thus we say an indefinite line, meaning a line of any length. Some authors use the word indefinite nearly in the same sense as we commonly attach to the term infinite. According to these, an indefinite line is that which is without termination; the former, however, is the sense in which it is commonly em- ployed by modern mathematicians. INDEFINITE, in Grammar, is understood of nouns, pronouns, verbs, participles, articles, &c. which are left in an uncertain indeterminate sense. INDELIBLE, something that cannot be cancelled or effaced, as indelible ink. See INK. INDEMNITY, in Law, the saving harmless; or a writing to secure one from all damage and danger that may ensue from any act. INDENTED, in Heraldry, is when the outline of an ordinary is notched like the teeth of a saw. INDENTURE, in Law, a writing which comprises some contract between two at least; being indented at top, answer- able to another part which has the same contents. See Deed. INDEPENDENTS, or Cong Reg Ation Alists, a sect of pro- testant Dissenters, so called from their founder, maintaining that all Christian congregations are so many independent reli- gious societies, having a right to be governed by their own laws, without being subject to any further or foreign jurisdic- tion. INDETERMINATE, is nearly the same as Indefinite, the former being applied to numbers, as the latter is to geometrical lines, surfaces, &c. with this difference, however, that the word indeterminate commonly implies that number or quantity whose value cannot be assigned; and the former, that which may be of any magnitude. IND eter MINATE Analysis, is a very interesting branch of algebra, in which there are always given a greater number of un- known quantities than there are independent equations, by which means the number of solutions is indefinite, though it commonly happens that certain restrictions are introduced, such as re- quiring integral or rational numbers, which frequently limit the number of solutions, and even in some cases render the problem impossible. INDETERMINATE PRobleM, in Algebra, is that which admits of many different solutions and answers, called also an unlimited problem. INDEX, in Arithmetic and Algebra, is the same as exponent. IND ex of a Logarithm, called otherwise the Characteristic, is the integral part which precedes the logartihm, and is always z' I N 0 ‘I N D 509 DICTIONARY OF MECHANICAL SCIENCE . . one less than, the number of integral figures in the given num- | ber. Or otherwise, the index is always equal to the number of places that the unit's place of the proposed number is from the first effective figure, and is accounted positive when the first figure is to the left of the unit's place, and negative when it is to the right. - - Index of a Globe, is a small hand fitted to the extremity of the north pole, which turning round with it points out the time upon the hour circle. - w INDIA RU BBER. See CAouTCHOUC. INDIGATIVE, in Grammar, the first mood, or manner, of conjugating a verb, by which we simply affirm, deny, or ask something. . - ENDICTION, or: Roman INDICTION, (from indico, to pro- claim,) in Chronology, is a term used for a sort of epocha amongst the ancient Romans; the origin or commencement of which is not distinctly known. The Roman indiction consists of a cycle of fifteen years, and when expired begins anew, and goes on again in the same order without any dependence on the motions of the heavenly bodies. The popes since the time of Charlemagne have dated their acts by the year of indiction, which was fixed on the first of January, A. D. 313. At the time of their reformation of the calendar, the year 1582 was reckon- ed the 10th year of the indiction. Now this date when divided by 15 leaves a remainder 7, that is, 3 less than the indiction, and the same must necessarily be the case in all subsequent dates; therefore to find the indiction for any year, divide the date by 15, and add 3 to the remainder, which will be the indiction; 1826. - tº-mºº 15 thus in the present year 1826, we have = 121, and re- mainder 14; consequently 14 + 3 = 17, the indiction. INDICTMENT, is a written accusation of one or more per- sons, of a crime or misdemeanor, preferred to, and presented on oath by, a grand jury. An indictment may be found on the oath of one witness, unless it be for high treason, which re- quires two witnesses, and unless in any instance it is otherwise specially directed by acts of parliament. The sheriff of every county returns to every session of the peace, and every com- mission of oyer and terminer, and of general gaol delivery, twenty-four good and lawful men of the county, some out of every hundred, to inquire, present, and do all those things, which on the part of the king, shall be commanded therein. As many as appear are sworn of the grand jury, to the amount of twelve at the least, and not more than twenty-three. Being previously instructed in the articles of their inquiry, by a charge from the judge, they receive indictments preferred to them in the name of the king, but at the suit of any private prosecutor; and they only hear evidence on behalf of the pro- secution. They may not find part of an indictment true and part false, but must either find a true bill or an ignoramus for the whole. All capital crimes whatsoever, and all kinds of inferior crimes which are of a public nature, may be indicted, but no injuries of a private nature, unless they in some degree concern the king. And generally, where a statute prohibits a matter of public grievance, or commands a matter of public convenience, every disobedience to it is punishable, not only at the suit of the party grieved, but also by indictment. Yet if the party offending have been fined in any action brought by the party, such fine is a good bar to the indictment. Several offenders committing the same offence may be joined in one indictment. No indictment for high treason, or misprision thereof, (except indictments for counterfeiting the king's coin, seal, sign, or signet,) shall be quashed for mis-reciting, mis. §pºlling &c. ºnless ºception concerning the same be taken isatistinctoria, or woad a plant cultivated and even found wild in England. When arrived at maturity this plant is cut before any evidence given in open court, on such indictment. An indictment accusing a man in general terms, without ascer- taining the particular fact laid to his charge, is insufficient; nor can it be good, without expressly shewing some place where the offence was committed. - - There are several words of art, which the law has appro- priated for the description of an offence, which no circumlocu- iºn will supply; as feloniously, in the indictment of any felony; burglariously, in an indictment of burglary. And an indictment on the black act. for shooting at any person, must *:: that the offence was done wilfully and maliciously. " allowed to fall to a coarse powder. No clerk of assize, clerk of the peace, or other person, is allowed to take any money of any person bound over to give evidence against a traitor or felon, for the discharge of his recognizance, nor more than two shillings for drawing any bill of indictment against any such felon, on pain of five pounds to the party grieved, with full costs. Every person charged with felony or other crime, who on his trial is acquitted, or against whom no indictment is found by the grand jury, or who is dis- charged by proclamation for want of prosecution, should be immediately set at large in open court, without payment of any fee to the sheriff or gaoler. This however is usually deferred till after the assizes or sessions are over, when the judge or justices proceed to the gaol delivery. s Upon a certificate of an indictment being found, for ai. assault or other misdemeanor, and much more for a felony, a warrant is issued, on the application of the prosecutor, to take the party into custody, and he may be held to bail by a justice of the peace, or a judge. This was not formerly the practice upon indictments, but an action cannot be brought by the per- son acquitted, against the prosecutor of the indictment, with- out obtaining a copy of the record of his indictment and acquittal; which, in prosecutions for felony, it is not usual to grant, if there be the least probable cause to found such prose- cution upon. But an action on the case, for a malicious pro- secution, may be founded on such an indictment whereon no acquittal can be, as, if it be rejected by the grand jury, or be coram non judice, or be insufficiently drawn; for it is not the danger of the plaintiff, but the scandal, vexation, and expense, upon which this action is founded. However, any probable cause for preferring it is sufficient to justify the defendant, provided it do not appear that the prosecution was malicious. INDIGO, a dye prepared from the leaves and small branches of the Indigofera tinctoria. There are two kinds, the true and the bastard. The produce of the first is sold at a higher price, on account of its superiority, but that of the other is heavier. The first will grow in many soils; the second succeeds best in those most exposed to rain; both are liable to great accidents. Sometimes the plant becomes dry, and is destroyed by an insect frequently found on it; at other times the leaves are devoured in the space of twenty-four hours by caterpillars. It ought to be gathered in with great precaution, for fear of shak- ing off the far?na that lies on the leaves, and is very valuable, When gathered, it is thrown into the steeping-vat, which is a large tub filled with water. Here it undergoes a fermentation, which in twenty-four hours, at farthest, is completed. A cock is then turned to let the water (which is impregnated with a very subtile earth, constituting the blue substance) run into the second tub, called the mortar or pounding tub, where it is forcibly agitated with wooden buckets, full of holes, and fixed to a long handle. When the workmen perceive that the coloured particles collect by separating from the rest of the liquor, they leave off shaking the buckets, in order to allow time to the blue dregs to precipitate to the botton), where they are left to settle till .the water is quite clear, Holes made in the tub at different heights are then opened one after another, and this useless water is let out. The blue dregs remaining at the bottom having acquired the consistence of a thick muddy liquid, cocks are opened, which draw it off into the settler. It is thence poured into linen bags, and when the water has sufficiently drained from it, it is formed into, small lumps, and dried in the shade. Indigo is used in washing, to give a bluish colour to linen: painters also employ it in their water colours; and dyers cannot make fine blue without it. Indigo may be obtained from the merium tinctorium, and the down, washed, dried hastily in the sun, ground in a mill; placed in heaps, and allowed to ferment for a fortnight. It is. then well mixed, and made up into balls, which are piled upon each other, and exposed to the wind and sun. In this state they become hot, and exhale a putrid ammoniacal smell. When r the fermentation has continued for a sufficient time, the woad is The solution of indigo is well known in this country by the name of liquid blue, or sulphate of indigo. While concen- trated, it is opaque and black; but when diluted, it assumes a 6 O 510 I N D I N D DICTIONARY OF MECHANICAL SCIENCE. fine deep colour; and its intensity is such, that a single drop of the concentrated, sulphate is sufficient to give a blue colour to many pounds of water. Bergman ascertained the effect of different re-agents on this solution. Dropt into sulphurous acid, the colour was at first blue, then green, and very speedily destroyed. In vinegar it becomes green, and in a few weeks the colour disappears. In weak potash it becomes green, and then colourless. In weak carbonate of potash there are the same changes, but more slowly. In ammonia and its carbonate the colour becomes green, and then disappears. ... In a solution of sugar it became green, and at last yellowish. In sulphate of iron the colour became green, and in three weeks dis- appeared. In the sulphurets the colour was destroyed in a few hours. Realgar, white oxide of arsenic, and orpiment, produced no change. Black oxide of manganese destroyed the colour completely. - - - - INDIVIDUAL, in Logic, a particular being of any species, Or *hich cannot be divided into two or more beings equal or alike. . - - * x \ INDIVISIBLE, among metaphysicians, a thing is said to be indivisibly absolute, absolutely indivisible, that is, a simple being, and consists of no parts into which it may be divided. INDIVISIBLES, in Geometry, are those small elements or principles into which any body or figure may be resolved. According to the principles of this method, a line is said to consist of a number of contiguous points, or surface of lines, and a solid of surfaces; and because each of these elements Is supposed indivisible, if in any figure a line be drawn through the elements perpendicularly, the number of points in that line will be the same as the number of elements. Hence it follows that a parallelogram, prism, or cylinder, is resolvable into elements, or indivisibles, all equal to each other, parallel and like to the base; and a triangle, into lines parallel to the base, but decreasing from the base upwards in an arith- metical progression; so also the circles which constitute the parabolic conoid, and the several cocentric circumferences which constitute a circle, and the successive circumferences which make up the surface of a right cone, all decrease accord- ing to the same law. * . . . . . . . . tº The great facility attending the method of indivisibles is very obvious in the demonstration of the celebrated theorem of Archimedes, viz. “Every sphere is two-thirds of its circum- scribing cylinder,” the principles of which are as follows. Let A º B, D E. G D E F, and G. H. 2×TSR.G2. Tſ I K, represent a ...N.T. re hemisphere, in- ------------ * | ***.........— ........” JT verted cone, and I cylinder, having . RI equal bases and - - - altitudes, and all standing on the common base line A F K. Then it is easily demonstrated, that if any sections be made in these solids, by a plane passing parallel to the common base, that the section ef of the cylinder is equal to the two sections a b, c d, of the hemisphere and cone; and as this is the case in every parallel position of the cutting plane, it follows that the sum of all the sections of the cylinder, is equal to the sum of all the sections of the hemisphere and cone; and hence it is inferred, that the solidity of the cylinder is equal to the soli- dity of the hemisphere and cone. But the cone is a third part of the cylinder, having the same base and altitude, hence the hemisphere is equal to the remaining two-thirds. - INDORSEMENT, in Law, signifies any thing written upon the back of a deed or other instrument. On sealing of a bond, the condition of the bond may be indorsed. In order to the executing a justice of the peace’s warrant in another county, it must be indorsed by some justice in such other county. It is customary also to indorse the receipt of the consideration- money upon a deed. BILLs of Exchange are indorsed, and every indorser is liable to the full amount of the bill he puts his name on. - ; INDUCTION, in Law, is putting a clerk or clergyman in possession of a benefice or living to which he is collated or presented. See the article PARson. Induction is performed by a mandate from the bishop to the archdeacon, who usually issues out a precept to other clergymento perform it for him. \ It is done by giving the clerk corporal possession of the church, as by holding the ring of the door, tolling a bell, or the like; and is a form required by law, with intent to give all the parishioners due notice and sufficient certainty of their new minister, to whom their tithes are to be paid. This, therefore, is the investure of the temporal part of the benefice, as institu- tion is of the spiritual. And when a clerk is thus presented, instituted, and inducted into a rectory, he is then, and not before, in full and complete possession; and is called in law persona impersonata, or parson impersonnee. • * INDUCTION, is a term used by mathematicians to denote those cases in which the generality of any law, or form, is infer- red, from observing it to have obtained in several cases. Such inductions, however, are very deceptive, and ought to be ad- mitted with the greatest caution, as there are numerous cases in which a law may obtain for a considerable way, and ulti- mately fail when its uniformity is supposed certain. A remark- able instance of the failure of induction appears in many of those formulae which have been given for prime. numbers. Thus the formulae ac” + a + 41, by making successively a = 1, 2, 3, 4, &c. will give a series, the first forty terms of which are prime numbers, whence one might be induced to conclude the law to be universal; it fails however in the very next case, the forty-first term being a composite number. - - INDULGENCES, in the Romish church, are a remission of the punishment due to sins, granted by the church, and sup- posed to save the sinner from purgatory. . . . . According to the doctrine of the Romish church, all the good works of the saints, over and above those which were neces- sary towards their own justification, are deposited, together with the infinite merits of Jesus Christ, in one inexhaustible trea- sury. The keys of this were committed to St. Peter, and to his successors the popes, who may open it at pleasure, and by transferring a portion of this superabundant merit to any par- ticular person, for a sum of money, may convey to him either the pardon of his own sins, or release for any one in whom he is interested, from the pains of purgatory. Such indulgencies were first invented in the 11th century, by Urban II. as a recompense for those who went in person upon the glorious enterprise of conquering the Holy Land. They were afterwards granted to those who hired a soldier for that purpose; and in process of time were bestowed on such as gave money for accomplishing any pious work enjoincd by the pope. The terms in which the retailers of indulgences described their benefits, and the necessity of purchasing them, are so extrava- gant, that they appear almost incredible. If any man (said they) purchases letters of indulgence, his soul may rest secure with respect to its salvation. The souls confined in purgatory, for whose redemption indulgences are purchased, as soon as the money tinkles in the chest, instantly escape from that place of torment, and ascend into heaven. That the efficacy of indulgences was so great, that the most heinous sins, even if one should violate (which was impossible) the mother of God, would be remitted and expiated by them, and the person be freed both from punishment and guilt. That this was the unspeakable gift of God, in order to reconcile man to himself. That the cross erected by the preachers of indulgences was equally efficacious with the cross of Christ itself. “Lo the heavens are open ; if you enter not now, when will you enter : For twelve pence you may redeem the soul of your father out of purgatory; and are you so ungrateful, that you will not rescue your parent from torment 2 If you had but one coat, you ought to strip yourself instantly, and sell it, in order to pur- chase such benefits,” &c. - In the last year, (1825) the Pope, Leo XII. issued a Bull of Indication, appointing a jubilee for the whole of the Catholic church, and to continue through the whole of the year, during which period his holiness mercifully granted and imparted the most plenary and complete indulgence, remission, and pardon of all their sins, to all the faithful of Christ of both sexes. INDURATED MUD. The American volcanoes discharge torrents of mud, which seem to be strongly impregnated with iron. It has been said that similar torrents have issued from Etna and Vesuvius, but it is supposed that the appearances have arisen from melted snow. The grand volcanoes of Coto- paxi, Tungarunga, and Sangay, in South America, eject pro- I N F I N F 511. DICTIONARY of MECHANICAL SCIENCE. digious quantities of mud, and what is more remarkable, pro- digious quantities of fish, so as to infect the air with putrefac- tion. . These fish appear to be little injured, and are the same with those found in the rivulets at the bottom of the volcanoes, being a pimelodes silurus from two to four inches in length. These muddy eruptions become fertile clay, and are very pro- ductive. Ferrara gives an interesting account of a muddy eruption at Maculaba in Sicily. Sometimes this phenomenon appears with immense force. The inhabitants of the neigh- bourhood still (1826) remember with terror the eruption of 1777, one-of the most violent yet known. - - - INEBRIANTS, are defined to be such things as affect the nerves in a particular and agreeable manner, and through them alter and disturb the functions of the mind. They are properly divided into native and artificial; the former chiefly in use among the oriental and other nations, the latter principally throughout Europe. - Natural INEBRIANTs, are, 1. Opium, in use all over the east, and of which the Turks, through custom, swallow a drachm. 2. Pergamum harmala, Syrian rue. The seeds are sold in Turkey for this purpose; and with these, as Bellonius relates, the Turkish emperor Solyman kept himself intoxicated. 3. Maslac of the Turks, or bangue of the Persians, prepared from the dust of the male-flower of hemp, or from the leaves. 4. Bangue of the Indians, from the leaves of the hibiscus sahda- riffa. 5. Seeds of various species of the datura, or thorn apple. 6. Tinang, or betel of the Indians. 7. Roots of the black henbane. .8. The hyoscyamus physaloides. 9. Berries of the deadly nightshade. 10. Leaves of milfoil are used by the Dalekarliams to render their beer intoxicating. 11. Tobacco, and several others less material are mentioned; such as clay, saffron, and darnel. - Artificial INEBRIANts, are fermented liquors from farina- ceous seeds; wines and spirits drawn by distillation. With these is ranked the nectar of the gods, and the anodyne medi- cine of Homer, commonly called nepenthes; and the spells by which Medea and Circe produced their enchantments. INERTIA of MATTER, in Philosophy, a passive principle, by which bodies persist in a state of motion or rest, receive motion in proportion to the force impressing them, and resist as much as they are resisted. See MechANics. INFALLIBLE, something that cannot err, or be deceived. One of the great controversies between the Protestants and Papists, is the infallibility which the latter attribute to the pope; though in fact, they themselves are not agreed on that head, some placing this pretended infallibility in the pope and a general council. - - INFAMY, in Law, is a term which extends to perjury, gross cheats, &c. by which a person is rendered incapable of being a witness or juror, even though he is pardoned for his crimes. INFANCY, the first stage of life; in a medical and political view, extending from birth to about the seventh year. Treatment of Infants in Health.-The two primary objects of attention on the birth of an infant are warmth and cleanliness. There is generally too much eagerness in putting the child to the breast; who is often worried to suck before he becomes actuated by the instinctive principle of nature, or before the mother finds her breasts sufficiently filled with milk to satisfy his desire. It is generally about the third day after child-bed, that both are fully prepared. It is the duty of every mother to suckle her child. When in consequence of suppression of milk, and extreme delicacy, or disease of constitution, hired nurses must be resorted to, the young and the healthy should be selected, with a full breast of milk, and that milk as nearly as may be the age of the foster-child. If a proper nurse cannot be procured, diluted cow's milk, intermixed with a small quan- tity of farinaceous food, will generally prove the most con- venient mutriment. Cow's milk, however, is far less sweet than human, and hence the mixture now recommended should be enriched with some addition of sugar. The chief point of vilege an infant under the age of 21, as to common misdemea- attention is, that the farinaceous matter, whether in the form of pap or gruel, be sufficiently dilute, and pressed through a fine strainer, to free it from lumps. Cordials, aperients, and opi- ates, should be avoided in a state of health. . . . * - The great and natural use of clothes is for the purpose of warmth, and the looser and softer the substance is by which this warmth is communicated, the better. Most of the defor- mities of children are occasioned by improprieties in their dress. An attempt to give neatness to the form renders pres- sure necessary; and where a part is weak, and the pressure greater than on the neighbouring parts, such part will naturally yield to the impulse, and deformity will ensue. . . s Sleep is at all times necessary to health, in infancy it is par- ticularly so; for the stimuli of air and light alone are sufficient to exhaust the system in an hour or two. Nothing, however, can be more permicious than the too common practice of administer- ing eordials, opiates, &c., as often as the child seems restless, The situation of infants requires at first air of a moderately warm temperature; after which they may be gradually inured to a colder atmosphere, without any danger to their health. Too much warmth, however, is as prejudicial as the opposite extreme, and the more to be dreaded, as every time they are brought to the open air, they are exposed to the danger of catching cold. But it is not merely a cold air that is to be avoided, it is the air that is confined, and at the same time loaded with moisture. A confined damp air is the cause of many of the diseases by which children are afflicted. The nursery should be the largest and best aired room in the house. When children sleep in a cradle, they should not be wrapped up too closely. Neither when they are further grown, should more than one child sleep in the same bed. In short, the proper regulation is to keep the child as much as possible in one pure equal temperature, avoiding every thing that is damp or unwholesome. - . - * * - The first exercise that children usually receive, is that of being dandled in the arm, or moved gently up and down, which tends much to assist digestion. Rubbing them with the hand is also highly useful. . . . As children increase in growth, their exercise should be pro- portionably augmented, and the nurse should endeavour to give them as much motion with her arm as possible. As soon as a child is able to be put on its feet, it should be allowed to make use of them. Every member acquires strength in proportion as it is exercised; and children, by being accus- tomed to support themselves, will soon acquire strength for the purpose. Children also begin to use their feet by degrees; and by this gradual attempt, all danger of their legs becoming crooked, or unable to support the body, is avoided. Among the poorer classes, it is very common to allow chil- dren to sit or lie in one posture for a length of time: this is a practice much to be condemned. By the want of exercise, the health of children suffers; a relaxation of the system ensues, and rickets and other diseases are induced. The early and rigorous confinement of children at day schools, merits to be particularly reprobated. If sent early to school, the time of learning should never be long, and should be alter- nated with proper diversions and exercises suited to their period of life. Exercise within doors is not sufficient to effect the good pur- poses derived from it in the open air. Children, instead of being checked in regard of wholesome play, should be at all times encouraged in it. - To uniform exercise, add the use of the cold bath. By general immersion, the body is braced and strengthened, the general circulation increased, and all stagnation in the smaller vessels prevented. The commencement of this practice early will be the means of preventing the appearance of many con- stitutional diseases. And even where it cannot be employed to its full extent, still the extremities should be every day bathed in cold water, and afterwards well dried, and the skin well rubbed. In this view, boys should be encouraged to learn and practise the salubrious and useful exercise of swimming. INFANT, in Law, is a person under 21 years of age, whose capacities, incapacities, and privileges are various. 1. In criminal matters, the law of England does, in some cases, pri- nors, so as to escape fine, imprisonment, and the like; and particularly in the cases of omission, as not repairing a bridge, or a highway, and other similar offences; for, not having the command of his fortune till the age of 21, he wants the capacity to do those things which the law requires. But where there is any notorious breach of the peace, a riot, battery, or the like, §12 I N F (which infants, when full grown, are at least as liable as others to commit,.) for these, an infant above the age of 14 is equally, liable to suffer as a person of the full age of 21. With regard to capital crimes, the law is still more minute and circum- spect, distinguishing with greater nicety the several degrees of age and discretion. 2. In civil matters, the ages of male and , female are different for different purposes. A male at 12 years old may take the oath of allegiance; at 14, is at the years of discretion, and therefore may consent or disagree to marriage, may choose his guardian, and if his discretion be actually proved, may make his testament of his personal estate ; at 17 may be an executor; and at 21 is at his own disposal, and may alien his land, goods, and chattels. A female also, at 7 years of age, may be betrothed or given in marriage; at 9 is entitled to dower; at 12 is at the years of maturity, and there- fore may consent or disagree to marriage, and, if proved to have sufficient discretion, may bequeath her personal estate; at 14 is at the years of legal discretion, and may choose a guardian; at 17 may be executrix; and at 21 may dispose of herself and her lands, . So that full age, in male or female, is 21 years, which age is completed on the day preceding the anniversary of a person's birth; who till that time is an infant, and so styled in law. vileges, in order to secure them from hurting themselves by their own improvident acts. An infant cannot be sued , but under the protection, and joining the name, of his guardian; for he is to defend him against all attacks, as well by law as otherwise: but he may sue either by his guardian, or prochein amie, his next friend, who is not his guardian. This prochein amie may be any person who will undertake the infant’s cause ; and it frequently happens, that an infant, by his prochein amie, institutes a suit in equity against a fraudulent guardian. With regard to estates and civil property, an infant hath many pri- vileges. In general, an infant shall lose nothing by nonclaim, or neglect of demanding his right, nor shall any other laches or negligence be imputed to an infant, except in some very parti- cular cases. - - - - INFANTRY, in Military affairs, the whole body of foot- soldiers, whether independent companies or regiments. The word takes its origin from one of the infantas of Spain, who, finding that the army commanded by the king, her father, had been defeated by the Moors, assembled a body of foot-soldiers, and with them engaged and totally routed the enemy. In memory of this event, and to distinguish the foot-soldiers, who were not before held in much consideration, they received the name of infantry. - Heavy-armed INFANTRY, among the ancients, were such as | wore a complete suit of armour, and engaged with broad shields and long spears. They were the flower and strength of the Grecian armies, and had the highest rank of military honour, . . . . . . . . . , - Light-armed INFANTRY, among the ancients, were designed for skirmishes, and for fighting at a distance. Their weapons were arrows, darts, or slings. . . ... Light INFANTRY, among the moderns, have only been in use since the year 1656. They have no camp equipage to carry, of the infantry. Light infantry are the eyes of a general, and the givers of sleep and safety to an army. Wherever there is found light cavalry, there should be light infantry. They should | - is a point where a curve begins to bend a contraryway. be accustomed to the pace of four miles an hour, as their usual marching pace, and to be able to march five miles an hour upon | by declension and conjugation. all particular occasions. Most of the powers on the continent have light infantry. It is only of late years, that light infantry. came to be used in the British army; but now every regiment has a company of light infantry attached to it, whose station is on the left of the regiment, the right being occupied by the grenadiers. ! . . . . . . . . - • INFINITE, is a term applied to quantities which are greater. than any assigned quantities; also quantities that are less than any assignable quantity, are said to be infinitely small, Infinite also is sometimes, though improperly, used in the sºme, sense as indefinite, to denote a line or quantity to which na certain bounds or limits are prescribed. Infinite quantities are not necessarily equal, but may have. any ratio to each other; thus a line which is infinitely extended. pictionARY OF MECHANICAE scIFNGR. and thus to form four different, infinite planes, being to each The very disabilities of infants are pri- | attorney assig àny fees. * - R.N. R. from a certain point, in only one direction, is; but half that which is infinitely extended from the same point in two direes tions. . In the same way we may conceive a rectangular plane; to be extended in one, two, three, or four different directions; other as the numbers 1, 2, 3, and 4. . . . . - * : * * , In the same way, a solid may be conceived to be extended in six different directions; forming infinite solids, which shall have to each other certain and determinate ratios. . . . . . . . In the same way we may conceive an infinite quantity, which is infinitely less than another infinite quantity; thus, if two infi- nite right lines be drawn parallel to each other at any finite distance in a plane infinitely extended in all directions, the infinite space included between them, will be infinitely less than the infinite plane in which they are drawn, for the breadth or infinitely extended plane. - . INFiNite, that which has neither beginning nor end; in which sense God alone is infinite. See GoD. . . . . . INFINITE, or Infinitely Great Line, in Geometry, denotes only an indefinite or indeterminate line, to which no certain distance between these lines is infinitely less than that of the bounds or limits are prescribed. INFINITESIMAL, or INFINITELY. SMALL QUANtity, is that which is so small, as to be incomparable with any finite quan- tity whatever, or it is that which is less than any assignable quantity. . . . - in the Method of Infinitesimals, the element by which a quantity increases or decreases, is supposed to be infinitely small, and is generally expressed by two or more terms; some of which are infinitely less than the rest, which being neglect- ed, as of no importance, the remaining terms form what is called the difference of the proposed quantity. The terms that are thus neglected, are infinitely less than the other terms of the element, and are the same which arise in consequence of the acceleration or retardation of the generating motion, during the infinitely, small instant of time in which the element was generated; so that the remaining terms express the element that would have been formed in that time, if the generating motion, had continued uniform. - - - . . . ; These differences are, therefore, in exactly the same ratio to each other, as the generating motions or fluxions; and hence, though infinitesimal parts of the elements are neglected, the conclusions are accurately true, in consequence of what may be termed a compensation of errors. . . . INFLAMMABILITY, that property of certain bodies by which they kindle or catch fire. - . . . . INFLECTION, called also DIFFRAction and Deflection, in Optics, is a property of light, by reason of which, when it comes within a certain distance of any body, it will be either bent from it or towards it; which is a kind of imperfect reflec- tion or refraction. - +. r - s Experiments and observations seem to reduce the phenome- na of inflection to a single principle, viz. of the attraction of light towards bodies; which attraction becomes conspicuous when the rays of light pass within a certain distance of their surfaces. and their arms and accoutrements are much lighter than those | produces the singular phenomenon of the coloured fringes that accompany the inflection. - . . . . . . . . Besides their being bent, the rays of light are like- wise separated into colours by the vicinity of bodies, and this INFLection, or Point of Inflection, in the Higher Geometry, INFLection, in Grammar, the variation of nouns and verbs, INFLöRESCENCE, in Botany, a term used to denote the mode of flowering; the manner in which flowers are supported on their footstalks. . IN FORMA PAUPERIS. When any man who has a just cause of suit, either in chancery or any of the courts of common. law, will come before the lord keeper, master of the rolls, either of the chief justices, or chief baron, and make oath that he is not worth five pounds, his debts paid ; either of the said judges will, in his own proper court, admit him to sue in forma paw- peris, or as a poor man, and he shall have counsel, clerk, or ned him, to do his business, without paying INFORMA' ION, in Law, is nearly the same in the crown 1 N. H. | N. P. DIQTIONARY OF MECHANICAL SCIENCE. 513 office, as what in other courts. is galled a Declaration. See PRosecution. Informations are of two sorts: first, those which are partly at the suit of the king, and partly at that of a subject; and secondly, such as are only in the name of the king. The former are usually brought upon penal statutes, which inflict a penalty upon conviction of the offender, one part to the use of the king, and another to the use of the in- former. By the statute 31 Eliz. c. 5, no prosecution upon any penal statute, the suit and benefit whereof are limited in part to the king and in part to the prosecutor, can be brought by any common informer after one year is expired since the com- mission of the offence; nor on behalf of the crown, after the lapse of two years longer; nor where the forfeiture is originally given only to the king, can such prosecution be had after the expiration of two years from the commission of the offence. The informations that are exhibited in the name of the king alone, are also of two kinds: first, those which are truly and properly his own suits, and filed ea officio by his own imme- diate officer, the attorney-general; secondly, those in which, though the king is the nominal prosecutor, yet it is at the relation of some private, or common informer; and they are filed by the king's coroner and attorney in the court of the King's Bench, usually called the master of the crown office, who is for this purpose the standing officer for the public. The objects of the other species of information, filed by the master pf the crown office, upon the complaint or relation of a private subject, are any gross and notorious misdemeanors, riots, bat- teries, libels, and other immoralities of an atrocious kind, not peculiarly tending to disturb the government, (for those are jeft to the care of the attorney-general ;) but which, on account of their magnitude or pernicious example, deserve the most public animadversion. And when an information is filed, either thus, or by the attorney-general ea officio, it must be tried by a petty jury of the county where the offence arises: after which, if the defendant be found guilty, he must resort to the court for his punishment. INFORMES Stelle, unformed stars, are those which have not been yet reduced into constellations, and are otherwise called sporades. In the earlier ages of astronomical science, the most conspicuous only of the assemblages of stars were plassed as constellations. From the sporades of the ancient, the moderns have arranged many new asterisms, for an account of which we must refer the reader to Jamieson's Celestial Atlas. INFUSION, in Chemistry, is the maceration of any sub- itance in water, or any other liquid, hot or cold, in order to §xtract its soluble parts. The liquid which is thus impregnated is called an infusion, INFUSORIA, in Natural History, the fifth order of the class vermes, in the Linnaean system. They are simple microsco- pic animalcules. The process by which their numbers are some- times increased, is no less astonishing than their first produc- tion. Several of the genera often seem to divide spontaneously into two or more parts, which become new and distinct animals. INGOT, in the arts, is a small bar of metal made of a certain form and size. sold and silver, intended either for coining, or cxportation to foreign countries. INGRAFTING, in Gardening: See GRAFTING. INGRATITUDE, the opposite of gratitude. See GRATItude. Ingratitude is a crime so shameful, that there was never a man found who would own himself guilty of it; and, though too fre- quently practised, it is so abhorred by the general voice, that to an ungrateful person is imputed the guilt, or the capability, of all other crimes. The ungrateful are neither ſit to love their Maker, their country, nor their friends. Ingratitude perverts all the measures of religion and society, by making it danger- ous to be charitable and good matured. However, it is better to expose ourselves to ingratitude, than to be wanting in charity and benevolence. INGRESS, in Astronomy, is the entrance of the sun into any of the zodiacal signs, especially into Aries. INHALER, a machine used for steaming the lungs with the vapour of hot water, for the cure of a cough, cold, inflamed throat, &c. . - INHERITANCE, a perpetual right or interest in lands, invested in a person and his heirs. See Descent. The term is chiefly applied to the small bars of INHIBITION, a writ to inhibit or forbid a judge from fur. ther proceeding in a cause depending before him. Sometimes prohibition and inhibition are put together, as of the same im- port; but inhibition is most commonly a writ issuing out of a higher court-christian to a lower; and prohibition, of the king's court to an inferior court. INHIBITION, in Scots Law, a diligence obtained at the suit of a creditor against his debtor, prohibiting from selling or con- tracting debts upon his estate to the creditor’s prejudice. INJECTION, the forcibly throwing certain liquid medicines into the body, by means of a syringe, tube, or the like. INjection, in Surgery, the throwing in some liquor or medi- cines into a vein opened by incision. This practice, and that of transfusion, or the conveying the arterial blood of one man, or other animal, into another, were once greatly practised, but are now laid aside. * … * Anatomical INJection, the filling the vessels of a human, or other animal body, with some coloured substance, in order to make their figures and ramifications visible. * + INITIATED, a term properly used in speaking of the reli- gion of the ancient heathens; where it signifies being admitted to the participation of the sacred mysteries. The word comes from the Latin, initiatus of initiare, initiari; which properly signifies to begin sacrificing, or to receive or admit a person to the beginning of the mysteries, or of ceremonies of less im- portance. The ancients never discovered the deeper mysteries of their religion, nor even permitted some of their temples to be open, to any but those who had been initiated. See MYSTERY. - INJUNCTION, in Law, a writ generally grounded upon an interlocutory order or decree out of the Court of Chancery or Exchequer, sometimes to give possession to the plaintiff, for want of the defendant's appearance; sometimes to the king's ordinary court; and sometimes to the court-christian, to stop proceedings in a cause, upon suggestion måde, that the rigour of the law, if it take place, is against equity and conscience in that case; that the complainant is not able to make his defence in these courts, for want of witnesses, &c. or that they act erroneously, denying him some just advantage. The writ of in- junction is directed not only to the party himself, but to all and singular his counsellors, attorneys, and solicitors; and if any attorney, after having been served with an injunction, proceeds afterwards contrary to it, the Court of Chancery will commit the attorney to the fleet for contempt. But if an injunction be granted by the Court of Chancery in a criminal matter, the Court of King's Bench may break it, and protect any that pro- ceed in contempt of it. INK-MAKING. Inks are fluid compounds, designed to form characters, or figures, on paper, parchment, or such other substance as may be fit to receive them. There are two prin-. cipal kinds of ink,--writing, and printing ink. To make writing ink. To an infusion of gall-nuts add some solution of sulphate of iron (green copperas) and a very dark- blue precipitate will take place. - This precipitate is the gallic acid of the galls united to the iron of the green vitriol, forming gallat of iron. This is the basis of writing ink; add a little gum-arabic: or take eight ounces of Aleppo galls, in coarse powder; four ounces of log- wood in thin chips; four ounces of sulphate of iron (green cop- peras); three ounces of gum-arabic, in powder; one ounce of sulphate of copper (blue vitriol); and one ounce of sugarcandy. Boil the galls and logwood together in twelve pounds of water for one hour, or till half the liquid has been evaporated. Strain the decoction through a hair sieve or linen cloth, and then add the other ingredients. Stir the mixture till the whole is dis- solved, more especially the gum ; after which, leave it to subside for twenty-four hours. Then decant the ink, and preserve it in bottles of glass or stone-ware well corked.—Or the following formula for the preparation of good writing ink may be used : for writing ink, the following proportions of materials are deemed best; three ounces of finely bruised galls; one ounce of green vitriol; one ounce of logwood shavings; one once of gum-arabic ; half an ounce of bruised cloves ; one pint of distilled vinegar; one pint of distilled water. These mate- rials are to be put together in a bottle, and set in a warm place fourteen days, being well shaken every day. The coarser parts 53. 514 I N. K. 1 No DICTIONARY OF MECHANICAL SCIENCE, i being allowed to subside, the ink is poured off; and its quality is materially improved by dissolving a stick of Indian ink and ten grains of corrosive sublimate, in each quart; an ounce of brown sugar may also be added, if the ink is intended to be used in the copying press. . . . . . . . . . . . . To make red writing ink: Take a quarter of a pound of ther raspings of Brazil wood, and infuse it two or three days in vinegar. Boil the infusion for an hour over a gentle fire, and filter it while hot. Put it again over the fire, and dissolve init, first, half an ounce of gum-arabic, and then of alum and white sugar each half an ounce. - - - . . . . Printing Ink. Printers' ink is composed of lamp black and lin- seed or suet oil boiled, so as to acquire consistence and tenacity. The obtaining of good lamp black appears to be the chief diffi- culty in making this ink. The ink used by copperplate printers, differs from the last only in that the oil is not so much boiled, and the using of Frankfort black. - Sympathetic inks are such as do not appear after they are written with, but may be made apparent by certain means to be used for this purpose. A variety of substances have been used for this purpose. . We shall describe the chief of them. - 1. Dissolve sugar of lead in water, write with the solution, and when dry, no writing will be visible. When you want to make it appear, wet" the paper with a solution of alkaline sul- phuret, and the letters will immediately appear of a brown colour. Even the vapours of these solutions will render the writing apparent. . . . - 2. Write with a solution of gold in aqua regia, let the paper dry gently in the shade, and nothing will appear; but draw over it a ‘sponge wetted with a solution of tin in aqua regia, and the writing will appear of a purple colour. 3. Write with an infusion of galls, and when you wish the writing to appear, dip it into a solution of green vitriol; the letters will appear black. . . - 4. Write with diluted sulphuric acid, and nothing will be visible. To render it apparent, hold it to the fire, and the letters will instantly become black. x . . 5. The juice of lemons, or of onions, a solution of sal annulu- niac, green vitriol, &c. answers the same purpose." 6. Green sympathetic ink is made by-dissolving cobalt in nitro-muriatic acid : write with the solution, and the letters will be invisible till held to the fire, when they will appear green, but disappear completely again when removed into the cold." In this manner they may be made to appear and disap- pear at pleasure. , - y A very pleasant experiment of this kind, is to make a draw- ing, representing a winter scene, in which the trees appear void of leaves, then put the leaves on with this sympathetic ink; and upon holding the drawing near to the fire, the leaves will begin to appear in all the verdure of spring, and surprise those who are not in the secret. . - Blue sympathetic ink is made by dissolving cobalt in nitric acid ; precipitate the cobalt by potash; dissolve this precipi- tated oxyd of cobalt in acetic acid, and add to the solution one-eighth of common salt. This will form a sympathetic ink, which, when cold, will be invisible, but will appear blue by the heat of the fire. - - - INK, China, or Indian. and the blackness remains suspended in it for a eonsiderable time. Dr. Lewis, on examining this substance, found that it consisted of a black sediment insoluble in water, which ap- peared to be of the nature of the finest lamp-black, and of another substance soluble in water, and which putrified, and when evaporated left a tenacious jelly-like glue or isinglass. It appears probable therefore, that it may be imitated by using a very fine jelly, like isinglass, or size, and the finest lamp black, and incorporating them thoroughly. - INK, removing Stains of. The stains of ink on cloth, paper, or wood, may be removed by almost all acids; but those acids are, to be preferred which are least likely to injure the texture of the stained substance. The muriatic acid diluted with five or six times its weight of water, may be applied to the spot, and, after a minute or two, may be washed off, repeating the application as often as may be found necessary. But the vegetable acids are attended with less risk, and are equally - This ink is brought over in small ob- : long cakes, which readily become diffused in water by rubbing, effectual. A solution of the oxalic, citric, (acid of lemons,) or tartareous acids, in water, may be applied to the most delicate fabrics, without any danger of injuring them; and the same solutions will discharge writing but not printing ink. Hence they may be employed in cleaning books which have been de- faced by writing on the margin, without impairing the text. Lémon-juice, and the juice of sorrel, will also remove ink stains, ..but not so easily as the concrete acid of lemons, or citric acid. INNATE IDeAs, those supposed to be stamped on the mind from the first moment of its existence, and which it constantly brings into the world with it; it is a doctrine which Mr. Lockd has abundantly refuted. • * * . . . . . . . . . . INNS and INNkeepers. If one who keeps a common inn refuse either to receive a traveller as a guest in his house, or to find him victuals or lodging, upon his tendering a reasonable price for them, he is not only liable to render the damages for the injury in an action on the case, at the suit of the party grieved, but also may be indicted and fined at the suit of the king. In return for such responsibility, the law allows him to retain the horse of his guest until paid for his ‘keep; but he | cannot retain such horse for the bill of the owner, although he may retain his goods for such bill; neither can he detain one horse for the food of another. An innkeeper, however, is not bound to receive the horse, unless the master lodge there also. Neither is a landlord bound to furnish provisions, unless paid beforehand. If an innkeeper make out unreasonable bills, he may be indicted for extortion; and if either he or any of his servants knowingly sell bad wine, or bad provisions, they will be responsible in an action of deceit. Keeping an inn is not tra- ding, to make a man a bankrupt; but where an innkeeper is a chapman also, and buys and sells, he may on that account be a bankrupt. Innkeepers are clearly chargeable for the goods of guests stolen or lost out of their inns, and this without any contract or agreement for that purpose. But if a person come to an innkeeper, and desire to be entertained by him, which the innkeeper refuses, because in fact his house is already full, whereupon the party says he will shift among the rest of his guests, and there he is robbed, the host shall not be charged. If a man come to a common inn to harbour, and desire that his horse may be put to grass, and the host put him to grass accordingly, and the horse is stolen, the host shall not be charged.—Innkeepers may detain the person of the guest who eats, till payment. By the custom of London and Exeter, if a man commit a horse to an hostler, and he eat out the price of his head, the hostler may sell him upon the reasonable apprais- ment of four of his neighbours; yet he cannot justify the taking him to himself at the price it was appraised at. . INNUENDO, is a word used in declarations and law plead- ings, to ascertain a person or thing which was not named be- fore ; as to say he (innuendo the plaintiff) did so and so, when there was mention before of another person. Innuendo may serve for an explanation, where there is precedent matter, but never for a new charge ; it may supply what is already expressed, but cannot add or enlarge the importance of it. - INOCULATION, or BUDDING, in Gardening, is commonly practised upon all sorts of stone fruits; as nectarines, peaches, apricots, plums, cherries, as also upon oranges and jasmines; and indeed this is preferable to any sort of grafting for most sorts of fruit. For the method of performing it see GARDENING. INOCULATION, in a physical sense, is used for the trans- plantation of distempers from one subject to another, particu- larly for the engraftment of the small-pox; which, though of ancient use in the eastern countries, is but a modern practice among us, at least under the direction of art. . . . In the year 1717, Lady Mary Wortley Montague, wife of the English ambassador at Constantinople, had her son inoculated there at the age of six years; he had but few pustules, and soon recovered. In April 1721, inoculation was successfully tried on seven condemned criminals in London, by permission of his majesty. In 1722, Lady Mary Montague had a daughter of six years old inoculated in this island; soon after which, the children of the royal family, that had not had the small-pox, were inoculated with success; then followed some of the nobility, and the practice soon prevailed. And here we date the commencement of inoculation under the direction of art. From the example of the royal family in England, the praetice I N O I N' R DICTIONARY' OF ... MECHANICAL SCIENCE. 515 4 the cutis, but not left in. forehead and chin. and this suffices to produce the disease. was adopted in Germany, particularly in Hanover and its adjacent countries. . . . . . . . . . . . . . . . . . . After Mr. Maitland had succeeded with those he had inocu- lated in and about London, he introduced the practice into Scotland in the year 1726. Sweden soon followed the example of the British. Russia engaged one of our principal promoters and improvers of this art. And now there are not many coun- tries that do not more, or less practise it. - Different Modes of Inoculation.—The practice of inoculation having obtained in every part of the world, it may be grateful, at least to curiosity, to have a general account of the different modes that are and have been adopted in that practice. Inoculation with the blood of variolous patients has been tried without effect; the variolous matter only produces the variolous disease. The application of the variolous matter takes place in a sensible part only; the activity of the virus is such, that, the smallest atom, though imperceptible to any of our senses, conveys the disease as well as the largest quantity. Hence the most obvious method is, the prick of a needle or the point of a lancet dipped in the matter of a variolous pustule. Cotton or thread is used, that is previously rubbed with pow- dered variolous scabs; this thread is drawn with a needle through This is the method in some parts of the East Indies. The Indians pass the thread on the outside of the hand, between any of the fingers, or between the fore finger and thumb. The Thessalian women inoculate in the Some abrade the scarf skins, and rub in the powdered dry scabs, which fall from the pustules of patients with the small-pox. Many of the Greek women make an oblique puncture with a . needle, on the middle of the top of the forehead, on each cheek, the chin, each metacarpus, and each metatarsus; then drop in each a little of the pus just taken warm from a patient, and brought in a servant's bosom. Others in Greece, make several little wounds with a needle in one, two, or more places, in the skin, till some drops of blood ensue; then the operator pours a drop of warm pus fresh from a pustule, and mixes it with the blood as it issues out; then the wound is covered by some with a bandage, by others with half a walnut shell, placed with its concave side over each orifice. The Chinese convey a pellet of variolated cotton, with the addition of a little musk, into the nostrils of the patient; they collect dry pus- tules, and keep them in a porcelain bottle well corked ; and when they inoculate, they mix a grain of musk with three or four grains of the dry scales, and roll them in cotton. This method may be called inodoration. About Bengal, in the East Indies, the person who intends to be inoculated, having found a house where there is a good sort of small-pox, goes to the bed of the sick person, if he is old enough ; or if a child, to one of his relations, and speaks to him as follows:—“I am come to buy the small-pox.” The answer is, “Buy if you please.” A sum of money is accordingly given, and one, three, or five, pustules, for the number must always be odd, and not exceeding five, extracted whole, and full of matter. These are immediately rubbed on the skin of the outside of the hand between the fore finger and the thumb; The same custom prevails in Algiers, Tunis, Tripoli, and other countries. Very similar to the custom among the people about Bengal, &c. is that in Arabia, where on some fleshy part they make several punctures with a needle imbued in variolous matter, taken from a pustule of a favourable kind. Here they buy the small-pox, too, as follows:—The child to be inoculated carries a few raisins, dates, sugarplums, or such like, and shewing them to the child from whom the matter is to be taken, asks how many pocks he will give in exchange? The bargain being made, they proceed to the operation; but this buying, though still contiqued, is not thought necessary to the success of the operation. The Arabs say, that any fleshy part is proper, but generally they insert the matter between the fore finger and thumb on the outside of the arm. The Georgians insert the matter on the fore arm. The Armenians introduce the matter on the two thighs. In Wales, the practice may be termed infriction of the small-pox. There, some of the dry pustules are procured by purchase, and are rubbed hard upon the naked arm:or leg. The practice in some places is, to prick the skin between some of the fingers by means of two small needles joined to one another; and after having rubbed a little. of the matter on the spot, a circle is made by means of several punctures of the bigness of a common pustule, and matter is again rubbed over it. The operation is finished by dressing the wound with lint. Another custom is, to mix a little, of the variolous matter with sugar, and give it to be drank in any agreeable liquor. . Incisions have been made in the arms and legs, and thread, cotton, or lint, previously dipped in the variolous, matter, was lodged in them. The practice of: some is, to bathe the feet in warm water, and then secure lint dipped in variolous matter on the instep, or other part of the foot, where the skin is thin. Others apply a small blistering plaster; and when the scarf skin is elevated and slipped off, the variolus matter is applied to the surface of the true skin, and confined there by a little lint or plaster. Scratching the skin with a pin or needle, and then rubbing the part with lint previously dipped in variolous matter, is the custom in some places.—In the Highlands of Scotland they rub some part of the skin with fresh matter, or dip worsted in variolous matter, and tie it about the children's wrists. They observe, that if fresh matter is applied a few days successively, the infection is mdte certain than by one application. - We have thus given the history of inoculation for the small- pox, which not many years ago was justly regarded as one of the greatest discoveries which had been made for the benefit of mankind, and would still be regarded as such, had it not given place to one still more valuable and important, the vaccine inoculation or cow-pox, which now promises to banish the small-pox from the world. For an account of this, see WACCI- NATION. It would be quite unnecessary to enter into the detail of the advantages to be derived from inoculation for the small-pox, and the methods of performing or preparing for it formerly practised. But as a curious part of the history of this prac- tice, we shall just barely mention some of the objections which have been urged against it. It has been said, that inoculation for the small-pox is unlawful; that it is bringing a distemper on ourselves, and thus usurping the sacred prerogative of God; that the decrees of God have fixed the commission of every disease, and our precautions cannot prevent what he hath determined ; that we should not do evil that good may come; that the patient may die, and then his last moments are distressed, and the future reflections of his friends are grievous ; that fear is a dangerous passion in the small-pox, but inocu- lation increases the causes of fear, by lessening our faith and trust in God; that inoculation does not exempt from future infection; that other diseases are communicated with the mat- ter of the small-pox by inoculating it; that perhaps the dis- ease may never attack in the natural way; that it requires much thought to know what we should do with regard to inocu- lation; that it endangers others, and that the practice of ino- culation comes from the devil. , - INORDINATE PRoportion, is where there are three mag nitudes in one rank, and three others proportional to them in another, and you compare them in a different order. Thus suppose the numbers in one rank to be 2, 3, 9, and those of the other rank 8, 24, 36, which are compared in different order, viz. 2 : 3 : : 24 : 36; and 3: 9 :: 8:24. Then rejecting the mean terms of each rank, you conclude 2: 9:: 8: 36. INQUEST, in Law, an inquisition by jurors or a jury. INQUISITION, in Law, a manner of proceeding by search or examination, on the king's behalf, in cases of outlawry, or self- murder, to discover the lands, goods, &c. forfeited to the crown. Inquisition is also had upon extents of lands, tenements, &c., writs of elegit, and where, judgment being had by default, damages and costs are recovered. * * INquisition, in the Church of Rome, a tribunal in several Roman Catholic countries, erected by the popes for the exami- nation and punishment of heretics. is INROLLMENT, in Law, is the registering, recording, or en- tering in the rolls of the Chancery, King's Bench, Common Pleas, or Exchequer, or by the clerk of the peace, in the records of the quarter sessions, or any lawful act; a statute or recogni- zance acknowledged, a deed of bargain and sale of lands, and 516 ;I N & iſ N S DICTIONARY OF MEGHANICAL SCIENCE, the like. By statute 27 Henry VIII. c. 16, no lands shall pass whereby any estate of inheritance or freehold shall take effect, or any use thereof be made, by reason only of any bargain and sale thereof, except the bargain and safe be made by writing indented, sealed, and within six months inrolled in one of the king's courts of record at Westminster; or else within the county where the lands lie, before the clerk of the peace, and one or more justices. But by 5th Elizabeth, c. 26, in the coun- ties palatine, they may be inrolled at the respective courts there, or at the assizes. Every deed before it is inrolled is to be acknowledged to be the deed of the party before a master of chancery, or a judge of the court wherein it is inrolled, which is the officer's warrant for inrolling it; and the inrolment of a deed, if it be acknowledged by the grantor, will be a good proof of the deed itself upon a trial. * - - INSCRIBED FIGURE, in Geometry, is one which has all its angles in the sides or periphery of another figure, in which the former is said to be inscribed. To inscribe a circle in a triangle A B C. - Bisect any two of the angles A and B, and from the point of inter- section O, let fall the perpendicular OD ; so will O D be the radius and O the centre of the circle required. To inscribe a Polygon within, or to circumscribe a Polygon about a given Circle. - Bisect two of the angles of the given polygon A and B by the right lines AO, B O ; and from the point O, where they meet, with the radius A O, describe a circle which will circumscribe the polygon. Next, to circumscribe a polygon, divide 360 by the number of sides re- quired, to find the angle A O B; which set off from the centre O, and draw the line A B, on which construct the polygon as in the following problem. 2, On a given line to describe any given regular polygon. Find the angle of the polygon in the table, and at A set off an angle equal thereto; then drawing C A = A B, through the points C A B, describe a circle, and in this applying the given right line, as often as you can, the poly- gon will be described. Inscribed Hyperbola, that which lies wholly within the angles of its symptotes; as does the common or conical hyperbola. INSCRIPTION, a title or writing affixed to any thing, to give some farther knowledge of it, or to transmit some im- portant truth to posterity. Antiquaries are very curious in examining ancient inscriptions found on stones and other monuments of antiquity. Sanchoniathon, contemporary, as it G is said, with Gideon, drew most of the memoirs whereof his history is composed from inscriptions which he found in tem- ples and on columns, both among the Heathens and the Hebrews. - - INSECTS, are not furnished with red blood, but instead of it their vessels contain a transparent lymph. They are destitute of internal bones; but in place of them are furnished with a hard external covering, to which the muscles are attached, which serves them both for skin and bones; they are likewise without a spine formed of vertebrae. They are furnished with articulated legs, six or more. A very great number of insects undergo a metamorphosis, which takes place in all winged insects. They frequently change their skin in the progress of their growth. A very great number of insects are furnished with jaws placed transversely. The wings with which a very great number of insects are furnished, distinguish them from all other animals which are not furnished with a spine composed of vertebrae. Insects are generally oviparous. Scorpions and aphides during the summer months are viviparous. Incubation is not necessary for hatching their eggs. In many insects, such as the crab, lobster, &c., the external covering is very hard, and destitute of organization; it is composed of a calcareous earth, mixed with a small quantity of gelatine, formed by an exudation from the surface of the body. As its hardness would check the | in number from two to eight. | the compound eyes are very numerous; they amount in some | insects to many hundreds. | have only two eyes, but some have three, some four, some six, growth of the animal, nature has provided a remedy; all of these crustaceous insects cast their shell annually. The skin. of most other insects is softer and organized, being formed of a number of thin membranes, adhering closely to one another, putting on the appearance of horn. It owes its greater softness to a large portion of gelatine. The muscles of insects consist of fibres formed of fasciculi; there are commonly but two mus- cles to produce motion in any of their limbs, the one an extensor, the other a flexor. These muscles are commonly attached to a tendon, composed of a horny substance connected to the part which they are destined to put in motion. In most insects the brain is situated a little above the oesophagus; it divides into two large branches which surround the oesophagus, and unite again under it, from which junction a whitish nervous cord proceeds, corresponding to the spinal marrow of the superior animals, which extends the whole length of the body, forming in its course twelve or thirteen knots or ganglions, from each of which small nerves proceed to different parts of the body. It appears pretty evident that they possess vision, hearing, smell, and touch; as to the sense of taste, we are left to conjecture, for we are acquainted with no facts by which we can prove that insects do not enjoy the sense of taste. The eyes of insects are of two kinds: the one compound, composed of lenses, large, and only two in number; the other are small, smooth, and vary The small lenses which form The far greater number of insects some eight. The eyes of insects are commonly immovable. | Their ears have been discovered at the root of their antennae, and can be distinctly seen in some of the large kinds, as the lobster. The faculty of smelling is the most perfect of all their senses. Beetles, of various sorts, the different species of der- mestes, flies, &c. perceive at a considerable distance the smell of ordure and dead bodies. Insects feed on a great variety of substances; there are few things either in the vegetable or animal kingdoms which are not consumed by some of them. As many insects cannot transport themselves easily in quest of food, to places at a distance from one another, nature has furnished the perfect insects of many species with an instinct which leads them to deposit their eggs in situations where the larvae as soon as hatched may find that kind of food which is best adapted to their nature. Some insects, at different periods of their exis- tence, make use of aliment of very different properties; the Jarvae of some are carnivorous, while the perfect insect feeds on the nectareous juice of flowers. Some authors have assert- ed that insects have no lungs; but later experience and obser- vation shew, that no species wants them, or at least something similar to them ; and in many insects they are larger in propor- tion to their bodies than in other animals. In most of them they lie at or near to the surface of the body, and send out lateral pores or tracheae. Insects do not breathe through the mouth or nostrils; there are a number of vessels for the reception of air, placed along on each side of the body, which are commonly called spiracula, which are subdivided into a number of smaller vessels, or bronchiae; the vessels, or tracheae, which proceed from the pores on the sides, are not composed of a simple mem- brane, but are tubes formed of circular rugae; the spiracula are distinguishable, and are covered with a small scaly plate, with an opening in the middle like a button-hole, which is fur- nished with membranes or threads, to prevent the admission of extraneous bodies. - Insects are the only animals without vertebrae, in which the sexes are distinguished. All insects are either male or female, except in a few of the genera of the order of hymenoptera. The male is always smaller than the female. The colours of the male are commonly much more brilliant than those of the female, in some insects the colours of the male is totally different from that of the female: the antennae of the male are commonly of a different form, and larger than those of the female; frequently the males are furnished with wings, while the females have none; the female bee is furnished with a sting, while the male is des- titute of one ; the males of some insects are furnished with sharp prominent points, resembling horns situated either on the head or breast, which are either not perceptible, or very faintly marked, in the female. The parts essential to genera- I N. S. I. N.T. 517. DICTIONARY OF MECHANICAL SCIENCE. tion afford the best distinguishing mark; in most insects; they are situated near the extremity of the rectum. See ENToMoLog Y and LAR v A. - . . . - INSOLATION, in Pharmacy, a method of preparing certain fruits, drugs, &c. by exposing them to the heat of the sun’s rays; either to dry, to maturate, or to sharpen them; as is done in vinegar, figs, &c. The word comes from the Latin verb in- solare, which is used by Pliny and Columella, and signifies, to expose to the sun. . - . - INSOLUBILITY, in Chemistry. The insolubility of a sub- stance in a ſluid, which is the medium of chemical action, has an influence on that action, somewhat similar to that of cohe- sion, and is nothing but a modification of it in relation to the fluid in which it is exerted. - INSOLVENT, a term applied to such persons as have not where withal to pay their just debts. A person dying, and not leaving estate sufficient to discharge these, is said to die insolvent. 4. . . . . - INSPIRATION, among divines, &c. implies the conveying of certain extraordinary and supernatural notices of motions into the mind : or it denotes any supernatural influence of God. upon the mind of a rational creature, whereby he is formed to any degree of intellectual improvement, to which he could not or would not, in fact, have attained in his present circumstances in a natural way. . Thus the prophets are said to have spoken by divine inspiration. - . Some authors reduce the inspiration of the sacred writers to a particular care of Providence, which prevented any thing they | had said from failing or coming to nought; maintaining that they never were really inspired either with knowledge or ex- pression. According to others, inspiration is no more than a direction of the Holy Spirit, which never permitted the sacred writers to be mistaken. It is a common opinion, that the in- spiration of the Holy Spirit regards only the matter, not the style or words. . . . . . - - INSTALMENT, the establishing a person in some dignity. It is chiefly used for the induction of a dean, prebendary, &c. It is also uscd for the ceremony whereby the knights of the garter are placed in their rank, in the chapel of St. George, Windsor. It is sometimes termed installation. - INSTANT, such a part of duration wherein we perceive no succession; or it is that which takes up the time only of one idea in our minds. - - - - - INSTELLON, is used by some authors to denote those parts of space which are beyond the rigions of the solar system. INSTINCT, an appellation given to the sagacity and natural inclinations of brutes, which supplies the place of reason in mankind. - . - INSTITUTES, in Literary History, a book containing the elements of the Roman law. The institutes are divided into four books, and contain an abridgment of the whole body of the civil law, being designed for the use of students. See LAw. INSTITUTE, in Scots Law, when by disposition or deed of entail a number of persons are called to the succession of an estate one after another, the person first named is called the institute, the others substitutes. . - institution, in general, signifies the establishing or founding something. In the common law, it signifies the investing a clerk with the spiritualities of a rectory, &c. which is done by the bishop, who uses the following formula: “I institute you rector of such a church with cure of souls; re- ceive your cure and mine.” . . INSULATED, in Electricity, a term applied to bodies that are supported by electrics, or non-conductors, so that their communication with the earth by conducting substances is interrupted. . . . . . INSURANCE, LAws of. By the stat. 14 Geo. III. c. 48, no insurance shall be made on lives, or on any other event wherein the party insured hath no interest; and in all policies the name of such interested party shall be inserted, and nothing more shall be recovered thereon than the amount of the interest of the insured. This, however, does not extend to marine insu- rances. But as it was a common practice of insuring large sums without having property on board, and which were called wager policies or insurances, interest or no interest, and of | insuring the same goods several times over, it was enacted f t whole. : that all insurances, interest or no interest, or without further proof of the interest than the policy, or by way of gaming, or without benefit of salvage to the insurer, should be void except on privateers, or on ships or goods from the Spanish or Portu- guese dominions; and that no re-assurance shall be legal, unless the former insurer be insolvent or dead; and that in the : East India trade, the lending of money on bottomry, or ad re- spondentia, shall alone have a right to be insured for the money : lent; and , the borrower shall recover no more upon any insu- rance. than the surplus of his bottomry or respondentia bond. No insurance can be made on an illegal voyage. It is generally stipulated in policies, that the insurer shall not be answerable for any partial loss on certain articles, but on others less difficult : to be preserved at sea, but liable to partial injuries, shall be i liable for any partial loss above five per cent.; and was to all other goods, and the ship and freight, he shall only be liable for such losses above three per cent. But he is liable on all losses, ; however small, called general average, or losses occasioned by , the ship stranding; but this loss must be an immediate, not a remote consequence of the stranding. The commencement of the risk on the ship varies in most cases, and usually continues till the ship has been 24 hours at safe anchor. Upon goods it commences when they are on board, and continues till they are removed or landed. The ship insured must be fit to bear the sea and perform the voyage ; and if she deviates from the usual course, and stops at places not usually stopped at, with- Out a proper cause, the contract is void. - INSURANCE upon Life. See Assur ANce. INTACTAE, the same as As YMPTote. INTAGLIOS, precious stones, on which are engraved the heads of great men, inscriptions, and the like; such as we fre- quently see set in rings, seals, &c. - INTEGER, in Arithmetic, a whole number, in contradis- tinction to a fraction. INTEGRAL, or INTEGRANT, in Philosophy, appellations given to parts or bodies, which are of a similar nature with the INTEGRAL Calculus. See CALculus. . . ." INTEGRAL Calculus, is the reverse of the differential calcu- lus, and corresponds with our inverse method of fluxions; the finding of an integral to a given differential being the same as finding the fluent of a given fluxion, and is performed by the same rules. - . . . . . » INTEGUMENTS, in Physiology, the common coverings which invest the body, as the skin with the fat and cellular membrane. It is also the term of the body. - INTENDMENT, in Law, is the intention, design, or true meaning, of a person or thing, which frequently supplies what is not fully expressed; but though the intent of parties in deeds and contracts is much regarded by the law, yet it gannot take place against the rules of law. - . . - . . INtENDMENT of Crimes. This, in case of treason, where the intention is proved by circumstances, is punishable in the same manner as if it was put in execution. So, if a person enters a house in the night-time, with an intent to commit burglary, it is felony; also, an assault, with an intent to com- mit a robbery on the highway, is made felony, and punished with transportation, 7 Geo. II. c. 21. * . . . . . INTENSITY, in Physics, is the degree or rate of power or energy of any quality, as of heat and cold. The intensity of qualities, as gravity, light, heat, &c, vary in the reciprocal ratio of the squares of the distances from the centre of the radi- ating quality. INTENT, in the Civil Law, signifies to begin, or commence, an action or process. INTENTION, in Medicine, that judgment or method of cure which a physician forms to himself from a duc examination of symptoms. - INTENTION, in Physics, the increase of the power or energy of any quality, as heat, cold, &c. by which it stands opposed to remission, which signifies its decrease or diminution. INTENTion, in Metaphysics, denotes an exertion, of the .ntellectual faculties with more than ordinary vigour; when the mind with earnestness fixes its view on any idea, con- siders it on all sides, and will not be called off by any solici tation. 6 Q $8. I, N, TV I. N. Tº DiGTIQNARY QF MECHANICAL SCIENCE: ... INTERCALARY DAY, denotes the odd day which is inserted | in the kalendar every fourth year. See BiššExtile. , ... INTERCALARY, an appellation, given to , the odd: day inserted in leap-year; which was so called from calo calare, “to proclaim,” it being proclaimed by the priests with a loud | voice. But the term may with equal propriety apply to the insertion of any period of time, by astronomors and legislators, to make the entire civil year correspond with the passage of the earthin the zodiac, from solstice to solstice, or from equi- | nox to equinox. Thus, the Roman year once consisted but of in months; afterwards two more were added ; and from that time to the present, intercalations have been adopted in the reformation of the calendar. In remote times, when the Ram became the leader of the zodiacal signs, it was called Jubel; and the jubilee was proclaimed: at the festival of Jupiter Ammon, a ram was slain and eaten by the people of Thebes, and a male lamb was sacrificed by the Hebrews, on the 10th of the mouth Nisan, to commemorate their deliverance from Egypt at the vernal equinox, or when the sun was in Aries. INTERCEPTED Axis. See ABSCISA. . , * - INTERCOLUMNIATION, in Architecture, denotes the space between two columns, which is always to be propor- tioned to the height and bulk of the columns. * , INTERCOMMONING, in Law, is when the commons of two manors lie together, and the inhabitants of both have, i. out of mind, caused their cattle to feed promiscuously on them. * * - INTERDICT, an ecclesiastical censure, by which the Church of Rome forbids the performance of divine service in a king- dom, province, town,' &c. This censure has been frequently executed in France, Italy, and Germany: and in the year 1170, Pope Alexander III. put all England under an interdict, for- bidding the clergy to perform any part of divine service, ex- cept baptizing of infants, taking confessions, and giving absolu- tion to dying penitents. But this censure being liable to the ill consequences of promoting libértinism and a neglect of reli- gion, the succeeding popes have very seldom made use of it. INTEREST, is the allowance made for the loan or forbear- ance of a sum of money, which is lent for, or becomes due, at a certain time; this allowance being generally estimated at so much per cent. per annum, that is, so much for the use of £100 for a year, and this rate is by law fixed not to exceed £5, or in other words, the greatest rate of interest must not exceed 5 per cent. per annum. Interest is either simple or compound. Simple interest, is that which is allowed upon the principal, only for the whole time of the loan, or forbearance. The money lent or forborne is called the principal. The sum paid for the use of it, the interest. The interest of £100 for one year, is called the rate per cent. And the sum of any principal, and its interest, together, the amount. - . . . To find the Interest of any Sum for ‘any Period, and at any given Rate per cent, Say, as £100 is to the rate per cent. ; so | is any principal to its interest for a year. And then, as one year is to this interest, so is any given time to the interest for that time... Suppose; it were required to find the interest of £519.13s. 4d. for 33 years, at 5 per cent, per annum. First, 100 : 5 :: £519. 13s. 4d. : 3; ; ; 25 19 8 & t . . . : 5' 2 - Again, 1 |' * - - 2 7 £25.9s 6 8 | 20 gººmsºmºsºsºmº ... — £90 18 10 3, 19 . 66 — 12. * d: 8.00 ...That is, the interest of the proposed sum for 1 year, is £25. 19s. 8d.; and for 33 years, it is £90. 18s. 10d. as required. Again, to find the interest of £250, for 23 years at 5 per cent. As £100.: £5 :: £250 : £12 10s. As 1. year: £12 10s. :: 2; : £31. 5s. - . The following tables will much facilitate the computation of simple interest. . TABLE of the Interest of £1, for any Number of Days, at . . . . . . . different Rates of Interest. # .# 3 per Cent, Th; * 4 per Cent. Fºgºlf 5 per Cent. | 1 || 00008 •00009 •00010 2000.12 .00013 2 | "00016 || 00019 || 00021 •00024 .00027 3 || 00024 || 00028 -00032 ‘00036 •00041. 4 || 00032 •00038 ‘00043 •00049 -00054 5 || 00041 •00047 ‘00054 •00061 •00068 6 || 00049 •00057 '00065 •000.73 •00082 7 || 00057 || “.00067 *00076 •00086 •00095 8 || 00065 '00076 '00087 || 00098 -00109 9 || “O0073 •00086 *00098 •00110 || 00128 10 : 00082 •00095 •00109 •001.23 •00136 20 | 00164 -00191 •00219 •00246 •00273 30 || 00246 •00287 •00328 •00369 -00410 40 -00328 -00383 •00438 •00493 •00547 50 || 00410 -00479 •00547 -00616 •00684 60 -00493 •00575 •00657 •00739 •00821 70 '90575 00671 || 00767 -00863 || 00958 80 -00657 U0767 f -00876 •00986 •01095 90 •00739 •00863 •00986 •01109 •01232. 100 '00821 •00958 •01095 •91232 •01369 200 || 01643 •01917 •02191 •02465 •02739 300 || 02465 02876 || 03287 •03698 '04109 This table, it is obvious, will furnish, by the addition of two or three of its numbers, the interest for any number of days, and the following will in the same way find it for any number of years. TABLE of the Interest of £1, for any Number of Years not exceeding 25, at different Rates of Interest. 2 7 2ſ181 17 8 *:::A; 3 per Cent. Tºur 4 per Cent. Fº alf 5 per Cent. I '03000 || 03500 •04000 •04500 *05000 2 •06000 •07000 •08000 •09000 *10000 3 “O9000 • 10500 • 12000 *13500 “I 5000 4 12000 *14000 • 16000 • 18000 - || 20000 5 '15000 17500 •20000 22500 *25000 6 ‘18000 21000 *24000 *27000 "30000 7 "21000 •24500 •28000 '31500 •35000 8 *24000 °28000. •32000: 36000 '40000 9 *27000 -31500 36000 '40500 *45000 10 '30000 •35000 •40000 •45000' •50000 11 * : *33000 •38500 •44000 *49500 *55000 12 *36000 "42000 . . . 48000 *54000 -60000. 13 39000 45500 52000 *58500 + 65000 14 *42000 *49000 *56000 •63000 70000 15 *45000 •52500 •60000 •67500 •75000 16 "48000 •56000 *64000 •72000 "80000 17, “51,000 *59500 | 68000 76500 “85000 18 "54000 || $63000 •72000 "81000 ‘90000 19 ‘57000 •66500 •76000 •85500 '95000 20 *60000 *70000 | 80000 *90000 || 1:00000 21 -63000 || 73500 '84000 "94500, 1*05000 22 *66000 “77000 •88000 *99000 || 1:10000 23 "69000 "80500 ‘92000 | 1.03500 il'15000 24 || 72000 || | 84000 •96000 || 1:08000 || 1:20000 25 75000 '87500 |1:00000 | 1.12500 1-25000 To find the Interest of any Sum, for a given Time, by the pre- leeding Tables.—Add together the interests for the several periods corresponding with the proposed rate per cent. and that sum multiplied by the principal will be the interest required. Example. Required the interest of £400, for 4 years, 123 days, at 4% per cent. , , , w $. 1 N T I N T DIGTIONARY QF MECHANICAL SCIENGE. 519 4 years 1800000 . . . . . . 100 days 0123287 20 days 0012328 3 days -0003698 Tabular interest for. . . • * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * 1989318 . : . 400 £,775725200 s. 11 45040 12 d. 4|92480 - 4 3| 69920 Therefore £17. 11s. 4%d. is the interest required. Compound INTEREst, is that which arises from any sum or principal in a given time, by increasing the principal each payment by the amount of that payment, and hence obtaining interest upon both interest and principal. Hence it follows, that, except for the sake of brevity, compound interest would require no other rule than what is given for simple interest, for it is only necessary to find the interest upon the given principal; then add this interest to the principal, and find the interest upon this, and so on, through the whole number of payments. But this would be attended with immense labour, if the time was at all considerable, and therefore other methods of com- putation become necessary, p Now, in the first place, it is obvious, that if we know the amount of £1 for any period, the amount of any other princi- | pal p, will be equal to p times the former; we may therefore limit our investigation to the simple case of finding the com- pound interest and amount of £1 for any given number of years, at any given rate per cent. Let then r be the amount of £1 for one payment, whether yearly, half yearly, or quarterly. Then, as the amount is always proportional to the principal, we shall have, as 1 : y : : * : * : : 1-2 : 0°, &c. that is, if the amount of £1, for 1 payment, be r the amount of £1, for 2 payments E rº the amount of £1, for 3 payments = rº - the amount of £1, for n payments E r" and consequently the amount (a) of any principal (p) for (n) payments = p *, which being for the conveniency of calcula- tion put into the logarithmic form, becomes log. of a = log. p + n log. r. Suppose, for example, the amount of £50, for 15 years, at 5 per cent. were required, the payment being due yearly. Since the interest of £100 is £5, the interest of £1 is '05, and the amount of £1 in one payment 1-05. Hence by the above formula, log. 1:05 = 0-021189 - mult, by 15 0-317835 log. 50 = 1.698970 2016805 - The natural number to this logarithm is 103.946, or £103. 18s. 10d. the amount; from which, if the principal be extracted, it will leave the compound interest itself. By this means the amount and compound interest of any sum, for any period and ate per cent. may be readily computed.* - - But the same may be done still more expeditiously by means of the following table, which exhibits the amount of £1, for . number of years not exceeding 25. Hence the following rule :- - - - . . - * It is no uncommon thing to hear folks talk of a sum of money doubling itself in 14 years; yet the same persons seldom know more of the matter than is found in the ordinary but imperfect rule usually found in such books as Walkingham's Tutor's Assistant, a book, by the way, that has obtained an undeserved share of popularity, if compared with Kieth's or Joice's. Arithmetic. - - . . . . " TABLE. Shewing the Amount of £1; in a given Number of Years, jot - ::::::: *. at any Rate of Compound Interest, from 3 to 6 , per Cent. . • , * { . . . " - * | . - t Years '3per Cent, **cº 4 per Cent, l'º sº 5 per Cent, 6 per c. | 1 || 1:0300 || 1:0350 || 1:0400 l'0450 | 1,0500 |1-0600 : 2 || 1:0609 || 1:0712 1-0816 1-0920 1-1025 || 1: 1236 3 1-0927 | 1'1087 || 1: 1248 || 1:14] 1 || '1' 1576 1, 1910 | 4 || 1:1255 . . i*1475 || 1' 1698 || 1"1925 | 1°2155 . A-2624 | 5 || 1:1592 || 1:1876 || 1:2166 || 1:2461 1°2762 || 1:3382 Ł 6 || 1:1940 || 1:2292 || 1°2653 || 1:3022 || 1'3400 l'4.185 7 || 1:2298 | 1:2722 || 1:3159 || 1:3608 || 1:4071 || 1:5036 8 || 1:2667 || 1:3168. 1°3685 || 1:4221 | 1.4774 1:5938 9 || 1:3047 1°3628 1'4233 || 1 “4860 1'55.13 || 1:6894 10 || 1:3439 1°4105 || 1'4802 || S5529 | 1.6288 || 1:7908 11 || 1:3842 | 1.4599 || 1:5394. 16228 17103 18982 12 || 1:42.57 || 1:5110 || 1'6010 || 1'6958 17958 ||2-0 12! I3 | 1.4685 1-5639 . H. 1"6650 1°7721 1°8856 2. 1329 14 || 1:51.25 | 1.6.186 || 17316 1 '8519 19799 2.2609 15 || 41'5579 1-6753 || 148009 'I'9352 || 2:0789 |2-3965 I6 || 1:6047 || 1:7339 1'8729 || 2:0223 2:1828 |2-5403 17 | 1.6528, 17946 19479 2.1133 || 2:2920 |2-6927 18 1-7024 - 1-8574 2-0258 || 2'2084 || 2°4066 |2-8543 19 17535 | 1-9225 || 2:1068 || 2:3078 || 2:5269 |5-0256 |. 20 | 1.8061 | 1.9897 || 2:1911 2'4117 | 2’6532 |5.2071 21 | 1.8602 || 2:0594 22787 || 2:5202 || 2:7859 |53995 22 | 1.9 161 2' 1315 || 2:3699 || 2:6336 || 2'9252 |5'6035 23 1.9735 22061 || 2:4647 2'7521 || 3:0715 |5-S197 24 || 2:0327 || 2:2833 2.5633 || 2:8760 || 3:2251 |4-0489 | 25 || 2:0937 2-3632 || 2:6658 || 3:0054 || 3:3863 |4°2918 Find the amount in the table for the given number of years and rate of interest, and multiply this amount by the principal for the amount required. Thus in the preceding example. Amount by the table = 267893 * Principal - 50 - 103.94650 - £103, 18s. 10d. as before.—This table is only computed for yearly payments, and therefore when the payments are different from these, or when the number of years or payments exceed 25, recourse must be had to the preceding rule. The accumulation of money, when placed at compound interest, after a certain number of years, goes on exceedingly rapid, and in some instances appears truly astonishing. One penny put out at 5 per cent. compound interest, at the birth of Christ, would, in 1810, have amounted to a sum exceeding in value 357 millions of solid globes of standard gold, each in magnitude as large as this earth ! The exact number of globes, according to this computation, is 357,474,600.-Barlow. INTERIOR ANGLE of A POLY GON, that which is formed internally by the meeting of any of the sides of the figure. INTERJECTION, in Grammar, an indeclinable part of speech, signifying some passion or emotion of the mind. INTERLOCUTORY Decree, in English Law. In a suit of equity, if any matter of fact be strongly controverted, the fact is usually directed to be tried at the bar of the court of King's Bench, or at the assizes, upon a feigned issue. If a question of mere law arises in the course of a cause, it is the practice of the court of Chancery to refer it to the opinion of the judges of the Court of King's Bench, upon a case stated for that purpose. In such cases, interlocutory decrees or orders are made. INTERLocutoRY Judgments, are such as are given in the middle of a cause, upon some plea, proceeding on default, which is not intermediate, and does not finally determine or complete the suit. But the interlocutory judgments most usually spoken of, are those incomplete judgments, whereby the right of the plaintiff is established, but the quantum of damages sustained by him is not ascertained, which is the province of a jury. In such a case, a writ of inquiry issues to the sheriff, who summons a jury, inquires of the damages, and returns to the court the inquisition so taken, whereupon the plaintiff's attorney taxes costs, and signs final judgment. 520 I N T 'I N T . DITIONARY OF MECHANICAL SCIENCE, InterlocutoRY Order, that which decides not the cause, but only settles some intervening matter relating to the cause. As where an order is made in Chancery, for the plaintiff to have an injunction to quit possession till the hearing of the cause; this order, not being final, is called interlocutory, INTERLUDE, an entertainment exhibited on the theatre between the acts of a play, to amuse the spectators while the actors take breath and shift their dress, or to give time for changing the scenes and decorations. In the ancient tragedy, the chorus.sung the interludes, to shew the intervals between the acts. Interludes, among us, usually consist of songs, dances, feats of activity, concerts of music, &c. Aristotle and Horace give it for a rule, that the interludes should consist of songs built on the principal parts of the drama; but since the chorus has been laid aside, dances, buffoons, &c. ordinarily finish the interludes. INTERMEDIATES, in Chemistry a term made use of when speaking of chemical affinity. Oil, for example, has no affinity to water unless it be previously combined with an alkali; it then becomes soap, and the alkali is said to be the intermedium which causes the union. INTERNAL, in general, signifies whatever is within a thing. Euclid (lib. 1. prop. 32,) proves that the sum of the three angles of every triangle is equal to two right angles ; whence he de- duces several useful corollaries. He likewise deduces from the same proposition, this theorem, viz. that the sum of the angles of every rectilinear figure, is equal to twice as many right angles as the figure hath sides, excepting or subtracting four. { INTERPOLATION, in Analysis, is the method of finding any inter mediate term in a series, its place or distance from the first term being given. This is commonly effected by means of the successive differences of the given terms, and is there- fore sometimes called the differential method, though this latter expression is more commonly employed to denote the method of summing up of series by means of interpolation; saving, in many cases, immense laborious calculations. Thus, for example, in finding the places of some of the planets, whose motion is not very rapid, it will be sufficiently accurate to find their places by calculation for every fourth or fifth day, and then, by means of the methods above described, their places for all the intermediate days may be found by interpolating between the known terms, which method will give a result much nearer the truth than by proportional parts, because this supposes a uniformity both in motion and time, which is not correct. . Agaid, in computing the moon's place for any particular hour, supposing its place for every day at noon to be given, the method of interpolations may be applied with great suc- cess, the result having scarcely any sensible difference from those that arise from actual computation, and we may thus frequently avoid one of the most laborious of astronomical calculations. By this means also the place of a comet, at any particular time, may be ascertained, from observations made on it prior to, and subsequent to, that precise period, as also the times of the equinoxes and solstices, which are determined much more accurately by this means than can be done by pro- portional parts, for in this we are obliged to suppose that the sun's declination increases and decreases proportionally to the distance of this body from the equinoctial point; which is evidently a false hypothesis. In fact, astronomy has derived more assistance from this theory than any other of the mathe- matical sciences, although it has been applied to other pur- poses with very great success. g INTERPOSITION, the situation of a body between two others, so as to hide them, or prevent their action. The eclipsc of the sun is occasioned by an interposition of the moon be- tween the sun and us; and that of the moon, by the interpo- sition of the earth between the sun and moon. See ECLIPSE. INTERROGATION, or Point of Interrogation, in Grammar, a character of this form (?) serving to denote a question. INTERROGATORIES, in Law, are particular questions demanded of witnesses brought in to be examined in a cause, especially in a court of Chancery. And these interrogatories must be exhibited by the parties in suit on each side; which are either direct for the party that produces them, or counter; or cross interrogatories. They are to be pertinent, and only to the points necessary; and either drawn or perused by coun- t = * * * * * sel, and to be signed by them. INTERSECTION, in the Mathematics, signifies the cutting of one line or plane by another. Thus, we say, that the mutual intersection of two planes is a right line. INTERVAL, in Music, the distance between any given sound and another, strictly speaking, is not measured by any common standard either of extension or duration; but either by immediate sensation, or by computing the difference between the numbers of vibrations produced by two or more sonorous bodies, in the act of sounding, during the same given time. As the vibrations are slower and fewer during the same instant, for example, the sound is proportionally lower or graver; on the contrary, as during the same period the vibrations increase in number and velocity, the sounds are proportionally higher or more acute. An interval in music, therefore, is properly the difference between the number of vibrations produced by one. Sonorous body of a certain magnitude and texture, and of those produced by another of a different magnitude and tex- ture, in the same time. Intervals are divided into consonant and dissonant. A consonant interval, is that whose extremes, or whose highest and lowest sounds, when simultaneously heard, coalesce in the ear, and produce an agreeable sensation, called by Lord Kames a tertium quid. A dissonant interval, on the contrary, is that whose extremes, simultaneously heard, far from coalescing in the ear, and producing an agreeable sensation, are each of them plainly distinguished from the other, produce a grating effect upon the sense, and repel each other with an irreconcileable hostility. In proportion as the vibrations of different sonorous bodies, or of the same sonorous body in different modes, more or less frequently coincide dur- ing the same given time, the chords are more or less consonant. When these vibrations never coincide at all in the same given time, the discord is consummate, and consequently the interval sºlely dissonant. But for a full account of these, see USIC. INTESTATES : there are two kinds of intestates, one that makes no will at all; and another that makes a will, and nomi- nates executors, but they refuse. The ordinary by special acts of parliament is required to grant administration of the effects of the deceased to the widow or next of kin, who shall first pay the debts of the deceased, and then distribute the surplus among the kindred in the proportions directed by 22 and 23 Car. II. c. 10. INTESTINA, in Natural History, the first of the five orders of the class vermes, in the Linnaean system. They are of a for- mation the most simple, being naked animals without limbs. Some live within other animals, some in water, and a few in the earth. INTESTINES, INTestiNE, in Anatomy, the entrails or bowels; those hollow, membranous, cylindrical parts, extended from the right orifice of the stomach to the anus, by which the chyle is conveyed to the lacteals, and the excrements are voided. See ANATOMY. INTONATION, in Music, the action of sounding the motes in the scale with the voice, or any other given order of musical tones. Intonation may be either true or false, either too high or too low, either too sharp or too flat; and then this word intonation, attended with an epithet, must be understood con- cerning the manner of performing the notes. The executing an air, to form the sounds, and preserve the intervals as they are marked with justness and accuracy, is no inconsiderable difficulty, and scarcely practicable, but by the assistance of one common idea, to which, as to their ultimate test, these sounds and intervals must be referred. These common ideas are those of the key, and the mode in which the performer is engaged; and from the word tone, which is sometimes used in a sense almost identical with that of the key, the word into- nation may perhaps be derived. It may also be deduced from the word diatonii, as in that scale it is most frequently con- versary; a scale which appears most convenient and most natural to the voice. We feel more difficulty in our intonation of such intervals as are greater or less than those of the diatonic order; because, in the first case, the glottis and vocal organs are modified by gradations too large, or too complex, in the sound. * - - INTORSION, in Botany, denotes the bending of any of the I N 'T 52ſ DICTIONARY OF MECHANICAL SCIENCE. I N V. parts of a plant towards one side, . This admits of certain dis- tinctions. 1. Twining stems which bend towards the left, as in hops, &c. but in convolvulus, &c. to the right. 2. Twining tendrils, which bend to the right and back again; of this kind are the tendrils of most of the leguminous plants, 3. Twisted flowers; in the periwinkle, the petals bend to the left; the pointal in the viscous campion is twisted to the left, as the seed-bud is in the screw tree. In oats, the beard which termi- nates the husk is twisted like a rope. In the violet, basil, &c. the upper lip of the corolla looks to the ground, and the under lip upwards. . . . , - INTRADOS, the internal curve of the arch of a bridge. INTRENCHMENT, in the Military art, any work that for- tifies a post against an enemy who attacks. It is generally taken for a ditch or trench with a parapet. Intrenchments are sometimes made of fascines with earth thrown over them, of gabions, hogsheads, or bags filled with earth, to cover the men from the enemy’s fire. - . INTRIGUE, an assemblage of events or circumstances, occurring in an affair, and perplexing the persons concerned in it., In this sense, it is used to signify the nodus or plot of a play or romance; or that point wherein the principal charac- ters are most embarrassed through the artifice and opposition of certain persons, or the unfortunate falling out of certain accidents and circumstances. In tragedy, comedy, or an epic oem, there are always two designs. The first and principal is that of the hero of the piece : the second contains the designs of all those who oppose him. These opposite causes produce opposite effects, to wit, the efforts of the hero for the execution of his design, and the efforts of those who thwart it. As those causes and designs are the middle, and these form a knot or difficulty which we call the intrigue, that makes the greatest part of the poem. It lasts as long as the mind of the reader or hearer is suspended about the event of those opposite efforts: the solution or catastrophe commences when the knot begins to unravel, and the diſficulties and doubts begin to clear up. The intrigue of the Iliad is twofold: the first comprehends three days’ fighting in Achilles' absence, and consists on the one side in the resistance of Agamemnon and the Greeks, and on the other, in the inexorable temper of Achilles. The death of Patroclus unravels this intrigue, and makes the beginning of a second. Achilles resolves to be revenged, but Hector opposes his design; and this forms the second intrigue, which is the last day's battle. In the AEneid there are also two intrigues: the first is taken up in the voyage and landing of Æneas in Italy; the second is his establishment there: the opposition he met with from Juno in both these undertakings, forms the in- trigue. †: it, it is certain they ought both to spring naturally from the ground and subject of the poem. Bossu gives us three manners of forming the intrigue of a poem : the first is that already mentioned; the second is taken from the fable and design of the poet; in the third, the intrigue is so laid, as that the solution follows from it of course. INTRINSIC, a term applied to the real and genuine values and properties, &c. of anything, in opposition to their extrinsic or apparent values. ** INTRODUCTION, in general, signifies any thing which tends to make another in some measure known before we have leisure to examine it thoroughly ; and hence it is used on a great variety of occasions. Thus we speak of the introduction of one person to another; the introduction to a book, &c.—It is also used to signify the actual motion of any body out of one place into another, when that motion has been occasioned by some other body. r - INTUITION, among Logicians, the act whereby the mind perceives the agreement or disagreement of two ideas, imme- diately by themselves, without the intervention of any other; in which case the mind perceives the truth as the eye does the light, only by being directed towards it. - INTUITIVE Evi DENce, is that which results from intuition. Dr. Campbell distinguishes different sorts of intuitive evidence; one resulting purely from intellection, or that faculty which others have called intuition; another kind arising from con- sciousness; and a third from that new-named faculty common sense, which this ingenious writer, as well as several others, As to the choice of the intrigue, and the manner of . understanding. INVALID, a person wounded, maimed, or disabled for action by age, . At Chelsea and Greenwich are magnificent hospitals, or rather colleges, built for the reception and accom- modation of invalids, or soldiers and seamen worn out in the service. We have also twenty independent companies of invalids, dispersed in several forts and garrisons. At Paris is a college of the same kind, called les Invalids, which is accounted one of the finest buildings in that city. INVECTIVE, in Rhetoric, differs from reproof, as the latter proceeds from a friend, and is intended for the good of the person reproved; whereas invective is the work of an enemy, and entirely designed to vex and give uneasiness to the person against whom it is directed. - - INVENTION, is used for the finding of any thing hidden. The Romish church celebrates a feast on the 4th of May, under the title of invention of the holy cross. - INVENTION, is also used for subtilty of mind, or somewhat peculiar to a man's genius, which leads him to a discovery of things new ; in which sense we say, a man of invention. INVENTION, in Painting, is the choice which the painter makes of the objects that are to enter the composition of his piece. See PAINTING. INVENTION, in Rhetoric, signifies the finding out and choos- ing of certain arguments which the orator is to use for the proving or illustrating his point, moving the passions or con- ciliating the minds of his hearers. Invention, according to Cicero, is the principal part of oratory; he wrote four books De Inventione, whereof we have but two remaining. INVENTION, in Law, a catalogue or schedule orderly made, of all the deceased person’s goods and chattels at the time of his death, with their value appraised by different persons, which every executor or administrator is obliged to exhibit to the ordinary at such time as he shall appoint. IN VENTRE SA MERE, is where a woman is with child at the time of her husband's death, which child if he had been born would be the heir to the land of the husband. A devise to an infant in ventre sa mere, is good by way of future exeeutory devise. And where a daughter comes into land by descent, the son born after shall put her out, and have the land. - INVERSE, is applied to a manner of working the rule of three, or proportion, which seems to go backward, or contrary to the order of the common or direct rule. See PRoPortion. INVERSE Proportion, or Inverse Ratio, in Philosophy, is that in which more requires less, or less requires more. Thus in the case of light and heat flowing from a luminous body, the light and heat are less at a greater distance ; and greater at a less distance. - ..INVERSION, or, as it is in Euclid, invertendo, or by inver- sion, is inverting the terms of a proportion by changing the antecedents into consequents, and the consequents into ante- cedents; thus, if t - a : b :: c : d . Then by inversion it will be 4 : 9: ; 12: 27 b : a . ; d. : c 9 : 4: ; 27 : 12 INVERSION, in Music, is a changed position either of a subject or of a chord. The inversion of a subject is produced by giving it a higher or lower situation among the several parts of a score. The inversion of a chord is that changed position of its component parts with respect to its fundamental bass, by which, though the harmony remains the same, the intervals are varied. * INversion, in Grammar, is where the words of a phrase are ranged in a manner not so natural as they might be. It is a considerable beauty either in verse or prose when we have it from an able hand; it gives vigour and variety to a sentence, and keeps the mind in agreeable suspense and expectation of a marvellous turn and conclusion. - INVERTED, in Music, is derived from the Latin preposition in and vertere, “to turn any thing a contrary way.” It signi- fies a change in the order of the notes which form a chord, or in the parts which compose harmony, which happens by sub- sitº; in the bass, those sounds which ought to have been 6 contends to be a distinct original source of knowledge, whilst others refer its supposed office to the intuitive power of the -> * * * . ... t ** - :- -#" ºś * -. † : 522 I N V I R I DICTIONARY OF MECHANICAL SCIENCE. * the upper part; an operation not only rendered practicable, ut greatly facilitated by the resemblance which one note has to another in different octaves, whence we derive the power of exchanging one octave for another with so much propriety and success, or by substituting in the extremes those which ought to have occupied the middle.station, and vice versa. See MUSIC. INVESTIGATION, properly denotes the searching or find- ing any thing out by the tracks or prints of the feet; whence mathematicians, schoolmen, and grammarians, came to use the term in their respective researches. - INVESTING A PLAce, is when a general, having an inten- tion to besiege it, detaches a body of horse to possess all the avenues, blocking up the garrison, and preventing relief from getting into the place, till the army and artillery are got up to form the siege. , * . . . * - INVESTITURE, in Law, a giving livery of seisin or posses- sion. There was anciently a great variety of ceremonies used upon investitures, as at first they were made by a certain form of words, and afterwards by such things as had the greatest resemblance to the thing to be transferred; thus, where lands were intended to pass, a turf was delivered by the granter to the grantee. In the church, it was customary for priests to make investiture of ecclesiastical benefices, by delivering to the person they had chosen a pastoral staff and a ring. - INVISIBLE COMBUSTION. This phenomenon was ob- served by Sir Humphrey Davy. When oxygen and hydrogen gases were made to unite together and inflame, water was the result of their combustion; but Sir H. observed that when these gases were made to pass through tubes of iron which were heated below redness, although no visible combustion appeared to the eye, nevertheless the two gases united, and water was the result. The same effect resulted from the application of a low heat in a variety of ways. In applying this principle to the improvement of the safety lamp, Sir H. Davy suspended some coils of fine platinum wire above the wick of the safety lamp in the wire gauze cylinder. If the lamp should be ex- tinguished by the quantity of fire damp, the glow of the plati- num will continue to guide the miner; and by placing the lamp in different parts of the gallery, the relative brightness of the wire shews the state of the atmosphere in those parts. Wher- ever the wire continues ignited, there is still sufficient oxygen to supportrespiration; for the ignition ceases when the foul air forms about two-fifths of the volume of the atmosphere. It is an advantage, that the platinum wire is of a very moderate price, and that it is imperishable in its duration. If the foul air be in such quantity as to stop the ignition, whenever the lamp is taken into a purer atmosphere, it again commences; and if the air become sufficiently pure, it will ignite so as again to light the wick of the lamp, which the fire damp had extin- guished. - - INVOICE, an account, in writing, of the particulars in mer- chandise, with their value, custom, charges, &c. transmitted by one merchant to another in a distant country. One copy of every invoice is to be inserted in the invoice book, and an- other must be despatched to the correspondent. A letter of ad- vice is generally subjoined. - INvoice Book, this book is paged, and contains copies of the invoices of goods sent to sea. INVOLUTE CURve, in the Higher Geometry, is that which is traced out by the extremity of a thread, as it is folded or wrapped about another figure or curve. See Evolute. INVOLUTION, in Algebra and Arithmetic, is the raising a given number or quantity to any proposed power. In arith- metical and in simple algebraical quantities, this consists only in multiplying the quantity as many times by itself as is neces- sary to produce the given power; the number of operations being one less than the index of the power to be produced; thus, a X a F a” . . . . . . . . . . 2d power, a X a X a F a” . . . . . . . . . . 3d power, a X a X a X a E a” . . . . . . . . . . 4th power, &c. So also, 2 × 2 . = 4. . . . . . . . . . 2d power of 2, 2 × 2 × 2 F 8. . . . . . . . . . 3d power of 2, . 2 × 2 × 2 × 2 = 16 . . . . . . . . . . 4th power of 2, &c. And in the same way we may proceed with compound alge- braical quantities; but for binomial ones, it is best to make action upon iodine. use of the binomial theorem, the general form of which is as follows, viz. . . * * - t - - t- I * . . . (a + b) = a + n aº-ib + *%+1) an -2 b 2 n (n − 1) (n − 2) + 1 .. 2 .. 3 Whence (a + b)* = a + 2 ab + bº - (a + b)* = a + 3 a2b + 3 abº + bº = a- + 4 a.ºb + 6 a.2b2 + 4 abº + bº &c. See BINoMIAL. IODIC Acid, may be obtained in the following way 2–Let barytes water act upon iodine, and an insoluble iodate of barytes will result. Wash it and pour upon it sulphuric acid equal to the barytes present, and heat the mixture. The iodic acid will quickly abandon its base, and mix with the water; but a little of the sulphuric acid will also be mixed with it. Add barytes water, and the two acids precipitate together. The density of iodic acid is greater than that of sulphuric acid. Expose it to a heat of from 600 to 700 deg, and it is melted and decomposed into oxygen and iodine. It deliquesces into air, and is very soluble in water. It destroys vegetable colours. It forms combinations with all the fluid and solid acids which it does not decompose. •' IODINE, was discovered in Paris, by M. de Courtois, a saltpetre manufacturer, who observed a rapid corrosion of his metal pots in preparing different sorts of sea-weeds which he used in making carbonate of soda. It is from sea-weeds alone that this product of nature is to be obtained. It has not yet been decomposed. Iodine is of a grayish black colour and metallic lustre. It is soft and friable to the touch. Its taste is very acrid. It is a deadly poison. It gives a brown stain to the skin, which soon vanishes by evaporation. The sp. gr. of iodine at 623 deg. is 4,948. It dissolves in 7000 parts of water, and the solution is of an orange-yellow colour. Iodine is incom- bustible, but with azote it forms a detonating compound; and in combining with several bodies it produces the phenomenon of combustion. The oxide of sodium, and, the subcarbonate of soda, are completely decomposed by iodine.— Iodine forms with sulphur a compound of a grayish black colour, radiated like sulphuret of antimony. Iodine and phosphorus combine with great rapidity at common temperatures, and produce heat without light. Oxygen expels iodine from both sulphur and phosphorus. Hydrogen, whether dry or moist, does not seem to have any action on iodine at the ordinary temperature ; but if we expose a mixture of hydrogen and iodine to a red heat in a tube, they unite together, and hydriodic acid is produced, which gives a reddish brown colour to water. Charcoal has no Several of the metals, as zinc, iron, tin, mercury, attack it readily, even at a low temperature, provided they be in a divided state; they produce but little heat, and but rarely any light. Iron is acted on by iodine in the same way as zinc, and a brown iodine results. Antimony presents, with iodine, the same phenomena as tin; the iodines of lead, copper, bismuth, silver, and mercury, are insohuble in water. This is at least the case with the above mentioned metals. There are two iodines of mercury; the one yellow, the other red ; both are fusible and volatile. When iodine and oxides act upon each other in contact, with water, its hydrogen unites with iodine to form hydriodic acid; while its oxygen on the other hand produces with iodine, iodic acid. Iodine of mercury has been proposed for a pigment. Iodine has been successfully given internally for the purpose of reducing the goitre, or swelling of the neck, IONIC ORDER. See ARCHITECTURE. Ionic Dialect, in Grammar, a manner of speaking peculiar to the people of Ionia. - IRIDIUM. Mr. Tennant, on examining the black powder left after dissolving platina, which, from its appearance, had been supposed to consist chiefly of plumbago, found it contain- ed two distinct metals, never before noticed, which he has named iridium, and osmium. The former of these was observ- ed soon after by Descostils, and by Vauquelin. Lead unites with it easily, but is separated by cupellation, leaving the iridi- um on the cupel as a coarse black powder. Copper forms with an-ºbs +, &c. | it a very malleable alloy, which after cupellation, with the addi- I R. R. I R. R. D1GTIONARY OF MECHANICAL scIENCE v tion of lead, leaves a small proportion of the iridium, but much less than in the preceding instance. Silver forms with it a per- fectly malleable compound, the surface of which is tarnished merely by cupellation; yet the iridium appears to be diffused through it in fine powder only. Gold remains malleable, and little altered in colour, though alloyed with a considerable pro- portion, nor is it separable, either by cupellation or quartation. IRIS, in Anatomy, the interior coloured part of the uvea of the eye, so called because of its variety of colours, iris being the Latin for rainbow. See ANATOMY and OPTICs. IRIS, the name of the rainbow, which see. IR is Marina, the Sea Rainbow. This elegant appearance is generally seen after a violent storm, in which the sea water has been much agitated. The celestial rainbow has great ad- vantage over the marine one, in the brightness and variety of the colours, and in their distinctness one from the other; for in the sea rainbow there are scarcely any other colours than a dusky yellow on the part towards the sun, and a pale green on the opposite side; the other colours are not so bright or distinct as to be well determined: but the sea rainbows are more fre- quent and more numerous than the others. It is not uncom- mon to see twenty or thirty of them at a time, at noon-day. IRON, is the most universally diffused metal throughout nature. It is found in animals, in vegetables, and in almost all bodies. It is seldom found native, but combined with a great variety of substances. It is particularly distinguished by its magnetical properties, by its hardness and elasticity, by its ductility, and the property of being welded, but it is very diffi- cult to fuse. Iron soon rusts or oxydates when exposed to the action of water. Iron filings agitated in water become oxyda- ted, and assume the form of a black powder, called martial Ethiops. When iron ore is fused in large furnaces, it is made to ſlow into a kind of mould formed in sand. This first product, which is exceedingly brittle, and not at all malleable, is called cast iron, of which are formed stoves, pipes, cannon, and other articles. Cast, or crude iron, contains carbon and oxygen. The presence of the former appears from its coating the utensils employed in its fusion with plumbage or black lead, which contains nine-tenths of carbon and one of iron. Crude iron is in three states, white, gray, or black, according as it contains a larger proportion of carbon, an exact propor- tion of carbon and oxygen, or a larger proportion of oxygen. To render the iron malleable, it must be freed from the carbon and oxygen which it contains; by being fused and kept in that state for some time, stirring and kneading it all the while ; by this the carbon and oxygen unite, and are expelled in the form of carbonic acid gas. It is then subjected to the action of large hammers, or to the pressure of rollers, by which the remaining oxyd of iron and other impurities are forced out. The iron is now no longer crystallized or granular in its texture; it is fibrous, and ductile, and is in a purer state, ‘though far from being absolutely pure. It is capable of being welded and worked by hammers into any form. forged or wrought iron. .There are several varieties of iron in this state, arising from the intermixture of other substances. There is one kind of forged iron, which when cold is ductile, but when heated is ex- tremely brittle; it is also fusible. This is termed hot short iron. Cold short iron possesses precisely the opposite proper- ties, being highly ductile while hot, but when cold extremely brittle. The causes of these peculiarities have not been per- fectly explained. Iron is capable of being reduced to a third state, which is that of steel. It is converted into steel by expos- ing it to heat in contact with carbonaceous substances, which unite themselves with it. Thus we have three states in which iron may exist, viz. cast iron, forged-iron, and steel. Cast iron contains too great a quantity of carbonaceous sub- stance ; it may be called steel too much steelified; it is there- fore exceedingly brittle, and not at all malleable. Forged iron is iron purified from all foreign substances. And in regard to its property of being welded, we may judge from the following account I am about to relate; for were it not for the property which iron has of being welded, that is, united in various parts without the assistance of rivets or solder, this very plentiful metal would be useless for many purposes; but as it is, what may not be accomplished by it! The most stupendous metallic It is now called { fabric ever executed by man, is the Chinese “bridge ofchains,” hung over an awful precipice near Ringtung, to connect twº mountains. In this bridge there are twenty-one chains, stretch- ed over the valley or abyss ; these are bound together by other chains which cross them. The whole forms a perfect and safe road, extending from the summit of one mountain to that of the other. A bridge, upon a similar principle, and of the same material, is now in the act of being erected over the Menai Strait, (to connect Wales with the Isle of Anglesea,) by Mr. Telford, the engineer. * x v - Steel is formed by bedding in charcoal, in a close furnace, alternate layers of malleable iron and charcoal, and exposing them to a strong fire for six or eight days. This process is called cementation. During this operation, the iron combines with a quantity of carbon, and is converted into blistered steel. This is either rendered more perfect and malleable, by subjecting it to the operation of the hammer, or it is fused, and cast into small bars, forming cast-steel. - r g Steel holds a middle rank between cast and forged, or mal- leable iron. It is composed of very small grains : and when hot, possesses a considerable degree of malleability. It is specifically heavier than forged iron. It is denser than forged iron, but is not harder. To communicate to it the neces- sary hardness, it must be tempered; that is to say, after being exposed to a greater or less degree of heat, according to the required degree of hardness, it must be suddenly cooled by immersion in cold water. Tempering renders it harder, more elastic, and more brittle. It may be made so hard as to scratch glass. Steel thus hardened, may have its softness and ductility restored, by again heating, and suffering it to cool slowly. - - A polished bit of steel, when heated with access of air, ac- quires very beautiful colours. It first becomes of a pale yel- low, then of a deeper yellow, next reddish, then deep blue, and at last bright blue. At this period it becomes red-hot, and the colours disappear; at the same time that the metallic scales, or the black imperfect oxyd of iron which is formed, incrusts its surface. All these different shades of colour indicate the dif- ferent tempers the steel has acquired by the increase of heat. Artists have availed themselves of this property, to give to sur- gical and other sharp instruments those degrees of temper which their various uses require. Tempered steel is more elastic, and harder, than iron. Its use is too well known to re- quire elucidation. - Wootz, a metal brought from the East Indies, was examined by Dr. Pearson, who discovered that it was iron united to carbon, and also to oxygen. { ; - The sulphate of iron is common copperas in an impure state. IRRATIONAL, an appellation given to surd numbers and quantities. See ALG EBRA. IRREGULAR, in Grammar, such inflections of words as vary from the general rules. IRRITABILITY, in Physiology, is the property peculiar to the muscles, by which they contract upon the application of certain stimuli, without consciousness of action. The laws of irritability are, 1. After every action in an irritable part, a state of rest, or cessation from motion, must take place before the irritable part be again incited to action. 2. Each irritable part has a certain portion or quantity of the principle of irritability which is natural to it, part of which it loses during action, or from the application of stimuli. 3. It regains this lost quantity during its repose or state of rest. . 4. Each irritable part has stimuli which are peculiar to it; and which are intended to support its natural action: thus blood, which is the stimulus proper to the heart and arteries, if by any accident it gets into the stomach, produces sickness or vomiting. 5. Each irritable part differs from the rest in regard to the quantity of irritabi- lity which it possesses. 6. All stimuli produce action in pro- portion to their irritating powers. 7. The action of every sti- mulus is an inverse ratio to the frequency of its application. 8. The more the irritability of a part is accumulated, the more that part is disposed to be acted upon. 9. If the stimuli which keep up the action of any irritable body be with- drawn for too great a length of time, that process on which the formation of the principle depends is gradually diminished, and at last entirely destroyed. 524, 1 T. C. I S L DICTIONARY OF MECHANICAL SCIENCE. ISATIS TINctori A, the plant called woad, used in dyeing. ISINGLASS. This substance is almost wholly gelatine ; 100 grains of good dry isinglass containing rather more than 98 of matter soluble in water. Isinglass is made from certain fish found in the Danube, and the rivers of Muscovy. Wil- loughby, and others inform us that it is made of the sound of the Beluga ; and Neumann, that it is made of the Huso Germa- morum, and other fish, which he has frequently seen sold in the public markets of Vienna. Mr. Jackson remarks, that the sounds of cod, properly prepared, afford this substance ; and that the lakes of America abound with fish from which the very finest sort may be obtained. Isinglass receives its diſferent shapes in the following manner. The parts of which it is com- posed, particularly the sounds, are taken from the fish while sweet and fresh, slit open, washed from their slimy sordes, divested of a very thin membrane which envelopes the sound, and then exposed to stiffen a little in the air. In this state, they are formed into rolls about the thickness of a finger, and in length according to the intended size of the staple ; a thin membrane is generally selected for the centre of the roll, round which the rest are folded alternately, and about half an inch of each ex- tremity of the roll is turned inwards. Isinglass is best made in the summer, as frost gives it a disagreeable colour, deprives it of its weight, and impairs its gelatinous principles. Isinglass boiled in milk forms a mild nutritious jelly, and is thus some- times employed medicinally. This, when flavoured by the art of the cook, is the blancmange of our tables. A solution of isinglass in water, with a very small proportion of some balsam, spread on black silk, is the court plaster of the shops. ISIS, Cor AL, in Natural History, a genus of the vermes zoo- phyta class and order. See CoRALLINEs. - ISLAND, or Isle, is a quantity of land entirely surrounded with water. Some conclude that islands are as ancient as the world, and it is by no means probable that the large islands far interior from the continent are new, and that they either arose out of the sea, or were torn from the main land. Nor is it less certain that there have been new islands formed by the casting, up of vast heaps of clay, mud, sand, &c. as that, for instance, of Tsongming in the province of Nanquin in China; or by the violence of the sea, which has torn off large promon- tories from the continent, as the ancients imagined Sicily, and even Great Britain, to have formed. It is also certain that some have emerged above the waves, as Santorini formerly, and three other isles near it lately; the last in 1707, which rose from the bottom of the sea, after an earthquake that was supposed to have loosened it from its hold. Several naturalists are of opinion that islands were formed at the deluge : others think they have been rent and separated from the continent by violent storms, inundations, and earthquakes. These last have observed that the East Indies, which abound in islands more than any other part of the world, are likewise more annoyed with earthquakes, tempests, lightnings, volcanoes, &c. than any other part. Varenius thinks most of their opinions true in some instances, and believes that there have been islands pro- duced each of these ways. St. Helena, Ascension, and other steep rocky islands, he supposes to have become so, by the seas overflowing their neighbouring champaigns. By the heap- ing up huge quantities of sand and other terrestrial matters, he thinks the islands of Zealand, Japan, &c. were formed. Sumatra and Ceylon, and most of the East Indian islands, he rather thinks were rent off from the main land; and concludes, that the islands of the Archipelago were formed in the same way; imagining it probable that Deucalion's flood might have con- tributed towards it. The ancients had a notion that Delos and some other islands rose from the bottom of the sea, which, how fabulous soever it might appear, agrees very well with some later observations. Seneca takes notice that the island Thu- asia rose out of the AEgean sea in his time, of which the mariners were eyewitnesses. Seneca mentions several floating islands in Italy; and later writers have described not a few of them in other places; but how true soever the histories of these might, have been at the time they were written, there remain very few proofs of their truth at present, these islands having either disappeared again, or been fixed to the sides, in some places, so as to have made a part of the sho Island of Ice, a name given to a great quantity of ice col- i lected into one solid mass, and floating upon the seas, near, or within the polar circles. Many of these fluctuating islands are met with on the coasts of Spitsbergen, to the great danger of the shipping employed in the Greenland fishery. sº IsLAND or Iceland Crystal, a body famous for its property of a double refraction; but improperly called by that name, as it has none of the distinguishing characters of crystal, being of a \ genus of spars. . It is always found in forms of an oblique parallelopiped, with six sides, and of various sizes, from a quar- ter of an inch to three inches or more in diameter. It is pellu- cid, and not much less bright than the purest crystal, and its planes are all tolerably smooth. All the surfaces are placed in the same manner, and it will split off into thin plates, either horizontally or perpendicularly. See Optics and ReFRAc. tion. It is very soft, and easily scratched with the point of a pin : it will not give fire on being struck against steel; fer- ments, and is perfectly dissolved in aquafortis. It is found in Iceland, from whence it has its name, and in France, Germany, and many other places. ISOSCELES TRIANGLE, (a word of Greek derivation,) is a * triangle of two equal legs or sides; such is the triangle A B C. The angles at the base of an isosceles triangle are equal, and if the sides be produced, the angles under the base are also equal. If the line B D be drawn perpendicular to the base, it will bisect the base and the vertical angle ; or if it be drawn to bisect the base, it will be perpendicular to it. This theory is of very extensive use, not only in pure analysis and geometry, but in various other subjects of mathematical inquiry and computation, and particularly in astronomy. ISOCHRONAL, Isoch Rone, Isoch RONUs, is applied to such vibrations of a pendulum as are performed in the same space of time. * IsochRoNAL Line, that in which a heavy body is supposed to descend without any acceleration. * ISSUE, in Common Law, has various applications, being sometimes taken for the children begotten between a man and his wife; sometimes for profits growing from amercements or fines; sometimes for profits of lands and tenements; but more frequently for the point of matter depending in suit, whereupon the parties join, and put their cause to the trial of the jury. In all the occasions, issue has but one signification, which is, an effect of a cause preceding: as the children are the effect of the marriage between the parents; the profits growing to the king or lord, from the punishment of any man’s offence, are the effect of his transgression; the point referred to the trial of twelve men, is the effect of pleading, ur process. See PLEA and Issue. ISSUES, in Surgery, are little ulcers made designedly by the surgeon, in various parts of the body, and kept open by the patient, for the preservation or recovery of his health. ISTHMUS, a narrow neck, or slip of ground, which joins two continents, or joins a peninsula to the terra firma, and separates two seas. See Pen INSULA. The most celebrated isthmuses are those of Panama or Darien, which joins North and South America; that of Suez, which connects Asia and Africa; that of Corinth, or Peloponnesus, in the Morea; that of Crim Tartary, otherwise called Taurica Chersonesus; that of the Peninsula Romania and Erisso, or the isthmus of the Thracian Chersonesus, twelve furlongs broad, being that which Xerxes undertook to cut through. The ancients had several designs of cutting the isthmus of Corinth, which is a rocky hillock, about ten miles over; but they were all in vain, the invention of sluices being not then known. There have been attempts too for cutting the isthmus of Suez, to make a com- munication between the Red Sea and the Mediterranean, but these also failed; and, in one of them, a king of Egypt is said to have lost 120,000 men. ITCH, a cutaneous disease, supposed to be caused by an insect, a species of the genus acarus, or spider of the human flesh, which, when viewed by a good microscope, is white, with reddish legs, the four hind ones having a long bristle. . It is found in the small pellucid vesicles in the hands and joints. I W 0. I V O DicTIONARY OF MECHANICAL science. 525 «» It appears to be not only the cause of the disorder, but the reason why it is so highly infectious. IVORY, in Natural History, &c. a hard, solid, and firm sub- stance, of a white colour, and capable of a very good polish. It is the tusk of the elephant; and is hollow from the base to a certain height, the cavity being filled up with a compact medullary substance, seeming to have a great number of glands in it. It is observed that the Ceylon ivory, and that of the island of Acheen, do not become yellow in the wearing, as all other ivory does; for this reason the teeth of these places bear a larger price than those of the coast of Guinea. As an article of domestic use, the shavings of ivory, which may be procured of any ivory turner, when boiled in water, form a strong and excellent jelly, equal in every respect to hartshorn jelly; and, at times, of great service to the sigk, particularly as the restor- ative virtues of ivory jelly are very great, and its flavour agree- able. Should the sending to a turner be inconvenient or im- practicable, any piece of ivory that may be at hand will answer the purpose by scraping it with a knife. In the manufacture of ivory and bone ornaments, and articles of domestic use, both these substances are softened by submitting them to the action of aquafortis for twelve hours, and subsequently to the juice of berries, we should say that of white currants, if the colour is to be preserved. This operation softens both ivory and bone to so pliant a degree, that they take any shape you may be dis- posed to give them in a die. They are again hardened by placing the articles in strong vinegar for four or five hours. When ivory is discoloured, it may be bleached or whitened by immersing it an hour in a solution of alum boiled in fair water. Then rub the ivory with a cloth, to prevent it drying too quickly, which sometimes makes it crack, and thus spoils a curious or valuable article. J. J A C J 2 is the jod consonant, which because of its different pro- nunciation, has likewise a diſſerent form, thus J,j. In Eng- lish it has the soft sound of g, nor is it used but when g soft is required before vowels, where g is usually hard; thus we say jacks jet, join, &c. instead of gach, get, goin, &c. which would be contrary to the genius of the English language. JABAROSA, in Botany, a name taken from the Arabic appellation of the mandrake Jaborosa, and given to a particular plant which agrees with it in habit, and almost in genus. JACK, a sort of flag, or colours, displayed from a stafferected on the outer end of a ship's bowsprit. In the British navy, the jack is a small union flag, but in merchant ships the union is bordered with red. - JACK in the Boz, a large wooden male screw, turning in a female one, which forms the upper part of a strong wooden box, shaped like the frustum of a pyramid. It is used by means of levers passing through holes in it, as a press in packing, and for other purposes. JACK, in Mechanics, a well-known instrument of common use for raising great weights, being a powerful combination of teeth and pinions, and the whole enclosed in a strong wooden stock or frame B C, and moved by a winch or handle H P ; the out- . side appearing as in fig. 1. © In fig. 2, the wheel or rack work is shewn, being the view of the inside Fig. 1. Fig. 2. when the stock is Al; Aé sº removed. Though |:== -º- just proportions and dimensions, for the supposed at least E ſº four times as long in ==#ESH * - illins-S. wheel Q, as the fi- |||||| | gure represents it; ==}= will be then four times more in num- 3 in the inch. Now if the handle H P be circumference of this radius will be 44 distance or space the power moves 54. = wº **º- # #léle& jºin º!E = -B - SES £ER ÉÉ *-* sºme Bă ºs *F# s Eſ º f it is not drawn in the % rack AB must be 9 Z/ proportion to the ## =#|| £ #=#|}= and the teeth, which ber, to have about 7 inches long, the inches, which is the B º J A C through in one revolution of the handle; but as the pinion of the handle has but four leaves, and the wheel Q suppose 20 teeth, or five times the number, therefore, to make one revolu- tion of the wheel Q, it requires 5 turns of the handle, when it passes through 5 × 44 or 220 inches; but the wheel having a pinion R, of 3 leaves, these raise the rack 3 teeth or 1 inch in the same space. Consequently the handle moving 220 times faster than the weight, raises 220 times its own energy. A man therefore who exerts a force of 50 lb, will by this jack raise 5 tons, or 220 × 50lb = 11000 lb weight. The improved jack has a pall or clock and ratchet, which prevents the machine from running back, if by any accident the weight should overbalance the power exerted. Jacks are sometimes open behind from the bottom almost up to the wheel Q, to allow the lower claw, which in that case is turned up at B, to draw up the weight. This is then kept from going back by hanging the end of the hook S, fixed to a staple, over the curved part of the handle at B. - JACK is also the name of a well-known engine in the kitchen, used for turning a spit. Here the weight is the power applied, acting by a set of pulleys; the friction of the parts, and the weight with which the spit is charged, are the forces to be over- come ; and a steady uniform motion is maintained by means of a fly. The common worm-jack is represented as follows:—A E C is the barrel round which the cord Q R is wound. K L the main lilllllllllllllllllllllllllllllll º s's wheel, commonly containing 60 teeth. N the worm wheel of about 30 teeth, cut obliquely. I is the pinion, of about 15. O 6 S 526 J A N J A L , DICTIONARY OF MECHANICAL SCIENCE. the worm or endless screw, consisting of two spiral threads, making an angle of 60 or 70 degress with its axis. X the stud, and Z the loop of the worm spindle. P a heavy wheel, or fly, connected with the spindle of the endless screw, to make the motion uniform. D G the struck wheel fixed to the axis F D. S, S, S, are holes in the frame, by which it may be nailed to a board, and thence to any wall, the end D being permitted to pass through it. H I the handle going upon the axis ET, to wind up the weight when it has run down. R is a box of fixed pulleys, and V a corresponding one of moveable pulleys carry- ing the weight. The axis ET is fixed in the barrel A C, which axis being hollow, both it and the barrel turn round upon the axis FD, which is fixed to the wheel KL, when it turns in the order BT A ; but cannot turn the contrary way, by reason of a catch mailed to the end A B, which lays hold of the cross-bars in the wheel L. K. The weight, by means of a cord QR, in consequence of its descent, carries about the barrel A B, which by the action of the catch carries the wheel K L, and this moves the pinion LM and wheel N, the latter moving the worm O, and the fly P. Also the wheel L. M carries the axis F D with the wheel D G, which carries the cord or chain that goes about the wheel or pulley at the head of the spit. But when the handle H gives motion to the axis in a contrary direction to that given by the weight, the catch is depressed; so that although the barrel B C moves and winds the cord upon it, the wheel D G continues at rest. The time which the jack will continue in motion de- pends upon the number of pulleys at R and V ; and as these increase or decrease, so must the weight which communicates the motion, in order to perform the same work in the same time. Smoke JACK, is an engine used for the same purpose as the common jack; and is so, called frºm itsillºſiń a_i\ being moved by Will | F. T T | means of the smoke #| || asºn. ºrched air as ſºlºkº 㺺l ! ||||| and striking against the sails of the hori- zontal wheel A B, which being inclined .."..."...";iº moved about the axis |||||W of the wheel together |||| C º iſſ cending the chimney, İſ |||| with the pinion C, which carries the |W sº º wheels D and E; and \| | ºp § E carries the chain F, ill : i\; which turns the spit. W 4 |||} * # ; ; The wheel A B should i||||||}º: | %| be placed in the nar- || |||}}}#} ºf j}|| p ºº ń ºº: ºney, where the mo- º | º º º § tº ſº. the largest volume of “ . & ſº it must evolve about the sails. Smoke jacks are sometimes moved by spiral flyers, coiling about a vertical wheel, and at other times by a vertical wheel with sails, like the float boards of a mill. JACTITATION of MARRIAGE, in Law, is when one of the party boasts, or gives out, that he or she is married to the other, whereby a common reputation of their matrimony may ensue. On this ground the party injured may libel the other in the spiritual court; and untess the defendant undertake and make out a proof of the actual marriage, he or she is enjoined perpetual silence on that head. . . & e JALAP, a root which is used in medicine as a purgative. Aceording to Dr. Henry, three kinds of jalap yielded as follows: Jalap leger. Jalap sain. Jalap pique. Resin. . . . . . . . . . . . 90 . . . . . . 48 . . . . . . 72 Extract . . . . . . . . . . 75 . . . . . . 140 . . . . . . 125 Starch . . . . . . . . . . . 95 . . . . . . 102 . . . . . . 103 Woody fibre.... 278 . . . . . . 210 . . . . . . 200 538 500 600 JAM, RASP Berry, is made by boiling fine ripe raspberries half an hour over a slow fire with their own weight of loaf sugar. and half their weight of white currant juice. The liquor should be cleanly skimmed while boiling, and then put into pots, covered with brandy paper. t • . Strawberry JAM, is made in the same manner. : JAMES’S Powners, or Antimonial Powders, a well known preparation, in medicine, of phosphate of lime and antimony. In a recent analysis of this valuable powder, it was found, to consist of peroxide of antimony 56° 0 parts, phosphate of lime 422 parts, oxide of antimony, impurity and loss 1-8 - 1000-0. See ANTIMONY. Phosphate of lime is a mineral produced by the combination of lime with phosphoric acid. In Spain there are entire rocks of phosphate of lime, which the inhabitants hew into building stones for houses, and for the walls of enclosures. This substance is also found in Cornwall; and other parts of England It constitutes the basis of the bones of all animals. The phosphate of lime which is sold in the shops is obtained from these by calcination. This mixed with wood-ashes is used in the manufacture of a kind of flat cups called eupels, which are employed by artists for reſining gold and silver in ; and from it phosphoric acid and the luminous substance called phosphorus are obtained. Phosphate of lime is said to be a very efficacious medicine in the disease called rickets, to which young children are liable. JANSENISTS, a sect of the Roman Catholics in France, who follow the opinions of Jansenius, bishop of Ypres, nearly like those of Calvin in relation to grace and predestination. JANUARY, the first month of the year, according to the present mode of reckoning, consisting of thirty-one days. The Iſalendar of Animated Nature for this month, in Middle- sex, presents, in its first week, shell-less snails and earth worms. In the second week, the redbreast whistles, the nut- hatch chatters, the mistletoe thrush sings, and wagtails appear. Indeed, these pretty wagtails appear on a fine day in all the months of winter. In the third week, the common larks con- gregate. In the fourth, snails and slugs abound in all the sheltered nooks of our gardens; the hedge sparrow whistles, the large titmouse sings, and some vagrant flies venture on the windows. * * The Kalendar of Vegetable Nature around London, presents | in the first week of January some plants accidentally in flower, as the laurustinus, continued from December. In the second week, winter aconite, Christmas rose in flower, and hazel cat- j kins, begin to appear; so do also the common honeysuckle buds. In the third week, we see primroses flowering in shel- tered places; and the humble daisy and chickweed begin to flower. In the fourth week, mezereon begins to flower, and sometimes spurry, pansy, white scented violet, archangel, and colt's-foot shew their blossoms. - Kitchen Garden. Of culinary vegetables, sow early frame and Charlton pease about the beginning, and dwarf marrowfats towards the end of the month. Early mazagan and long-pod beans in the first week and the last; hardy green Egyptian, and brown Dutch lettuces; early dwarf short top radishes.—Pro- tect, by temporary coverings, newly-sown seeds; transplant strong plants; dig and trench vacant ground in dry weather; prepare composts, and destroy insects. - Hardy Fruit Department. Plant fruit trees; protect newly planted trees; prune apples, pears, plums, cherries, goose- berries, currants, and raspberries.—Dig and stir the earth round trees that have been pruned ; trench ground for trees; stake newly planted trees; clean trees from moss and mistletoe. Destroy insects by washes. Look over the fruit in your store- room, and pick out all that are decayed. - Culinary Hot-house Department. Glass-case without heat; sow radishes, lettuce, carrots, small salads, and pease and beans for transplanting. Hot-beds and Pits. Prepare for making up hot-beds for early cucumbers and melons. Sow early radishes and small salad. Sow carrots on a slight hot-bed, to produce a crop for May. Kidney beans, pease, and potatoes, may also be sown, planted on slight hot-beds.—Give air and water sparingly to pines. Give air and water to forcing houses, and increase the stimuli according to the advancement of your crops. Flower Garden. Here we have the hot-house and open J A P J A P 527 DICTIONARY OF MECHANICAL scIENCE. ground departments. In the latter, plant dried roots of border flowers, transplant daisies as edgings, and protect choice plants by matting, &c. In the hot-house department, attend to alpines, which should have air daily if the weather is not very severe. In hot-beds and pits, force roses, shrubs, and hardy flowers. . . The mean temperature of the green-house should be 40° maximum, at fire heat 44°. The mean tempe- rature of the dry stove should be 45° with fire heat. Water sparingly, but give air daily. - In the Pleasure Ground and Shrubbery, plant most sorts of deciduous trees in fine weather, and deciduous hedges. Prune deciduous and naturalized shrubs and hedges. Continue to dig in the interior of masses and groups; and dress and gravel. Form and repair lawns and turf verges in mild eather. . & . - - Th’ees in the Nursery Department. Lay out ground, dig and trench, lift, prune, gather, protect trees, and destroy vermin. Trees in permanent Plantations and Park Scenery. Prepare ground for groves, and screen plantations; plant in dry wea- ther deciduous trees, pines, and larches; prune deciduous trees; cut hedge-rows; enclose and fence ground designed to be planted; fell timber trees, where the bark is no object; and thin crowded plantations. t - JAPANNING is the art of varnishing and painting ornaments on wood, as is done by the natives of the island of Japan. All substances that are dry and rigid, or not too flexible; as woods, metals, leather, and paper prepared; admit of being japanned. Wood and metals require no other preparation than to have their surfaces perfectly even and clean ; but leather should be securely stretched, either on frames or on boards; as its bind- ing would crack, and force off the warnish. Paper should be treated in the same manner, and have a previous strong coat of size; but it is rarely japanned, till converted into papier machié, or wrought into such form, that its flexibility is lost. Of Japan Grounds. . When a priming is used, the work must be smoothed with fish-skin or glass-paper, and being thoroughly clean, is brushed over once or twice with hot size, diluted with two-thirds water, if it is of the common strength. The priming is laid on as evenly as possible. between the common kind and glue, mixed with as much whit- ing as will give it a sufficient body of colour to hide the surface it is laid upon. This is repeated till the inequalities are filled up, then the work is cleaned off with Dutch rushes, and polished with a wet rag. When wood or leather is japanned, and no priming used, the best preparation is to lay on two or three coats of coarse varnish, composed in the following manner: Take one pint of rectified spirits of wine, and of coarse seed- lac and resin, each two ounces ; dissolve the seed-lac and resin in the spirit, and then strain off the varnish. This varnish, like all others formed of spirit of wine, must be laid on in a warm place ; and if it can be conveniently mannaged, the piece of work to be varnished should also be made warm; for the same reason, all dampness should be ºvoided ; as cold or moisture chills this varnish, and prevents its taking hold of the substance on which it is laid. When the work is so prepared, or by the priming with the composition of size and whiting above described, the proper japan ground must be laid on. This is best formed of shell-lac varnish, and the colour desired, except white, which requires a peculiar treatment; and if brightness be wanted, other means must be pursued. The colours used with the shell-lac varnish may be any pigments, which give the tint of the ground desired. As metals never require to be under- coated with whiting, they are treated in the same manner as wood or leather. & * - - White Japan Grounds, are made by the following compo- sition: . Take flake-white, or white lead, washed over and ground up with one-sixth of its weight of starch and then dried ; temper it properly for spreading with mastich varnish; and lay these on the substance to be japanned, prepared either with or without the under coat of whiting, as ordered above; and then varnish it over with five or six coats of the following warnish. * , - - . . From a quantity of the best seed-lac, pick out the clearest and whitest grains, reserving the fouler parts for coarse war- nishes, or for priming or preparing wood or leather. Of this picked lac take two ounces, and of gum animi three ounces; It is a size, of a consistency the seed-lac be added to it, to form the varnish. reduce them to a gross powder, and dissolve them, in about a quart of spirits of wine, and strain off the clear varnish. The seed-lac will give a slight tinge to this composition; but it can- not be avoided, when hard warnish is wanted ; though, when a softer will answer the end, the proportion may be diminished, and a little crude turpentine added to the gum animi to take off the brittleness. - A very good varnish, entirely free from brittleness, may be formed by dissolving as much gum animi as the oil will take, in old nut or poppy oil. This must be boiled gently when the gum is put into it. The ground of white colour itself is laid on in this varnish, and then a coat or two of it put over the ground; but when used, it must be well diluted with oil of tur- pentine. This, though free from brittleness, is liable to suffer by being indented or bruised by any slight strokes; and it will not bear any polish, but may be brought to a smooth surface without, if judiciously managed in the laying it on. It is tedious drying and requires time where several coats are laid on ; as the last should be without oil of turpentine. - Blue Japan Grounds are formed of bright Prussian-blue; or of verditer, glazed over by Prussian-blue, or smalt. The colour is best mixed with shell-lac varnish, and brought to a polishing state by five coats of varnish of seed-lac; but the varnish will somewhat injure the colour, by giving a cast of green to a true blue, and fouling a warm blue by the yellow it contains; where a bright blue is required, and a less degree of hardness can be dispensed with, we pursue the method directed in the case of white grounds. - Red Japan Grounds. For a scarlet, vermilion is used; but it has a glaring effect, much less beautiful than the crimson produced by glazing it over with carmine, fine lake, or rose pink. For a bright crimson, instead of glazing with carmine, use Indian lake, dissolved in the spilet of which the varnish is compounded; in this case, instead of glazing with the shell- lac warnish, the polishing coats are only used, as they equally receive and convey the tinge of the Indian lake, which may be dissolved by spirits of wine; but if the highest degree of white- ness is required, use the white varnish. For Yellow Japan Grounds, employ King's yellow, or turpeth mineral, either alone or mixed with fine Dutch-pink. The effect may be heightened, by dissolving turmeric root in the spirits of wine, of which the upper or polishing coat is made. The spirits of wine must be strained from off the dregs before The seed-lac varnish is not equally injurious here, and with greens; be- cause, tinged with a reddish yellow only, it is little more an addition to the depth of colour. Yellow grounds may be found of Dutch-pink only, which, when good, is not deficient in brightness, though extremely cheap. Green Japan Grounds, are prepared by mixing King's yellow and Prussian-blue, or turpeth mineral and Prussian-blue ; and a cheap but fouler kind, by verdigris, with a little of the above- mentioned yellows, or Dutch-pink. Where a bright green is wanted, the crystal of verdigris, (distilled verdigris,) are em- ployed; to heighten the effect, they are laid on a ground of leaf-gold, when the colour is extremely brilliant and pleasing. Orange Japan Grounds, are formed by mixing vermilion, or red lead, with King's yellow, or Dutch-pink, or the orange lake, which will make the brightest orange ground that can be produced. - Purple Japan Grounds, are produced by the mixture of lake and Prussian-blue; of a darker hue, by vermilion and Prus- sian-blue. With respect to the varnish, they are treated as the others. - - Black Japan Grounds, (formed without heat,) may be formed by ivory black, or by lamp-black; the former is preferable when good. These are laid on with shell-lac varnish; and have their upper or polishing coats of common seed-lac war- nish, the tinge of the warnish being no injury here. Common Black Japan Grounds on Iron or Copper, (formed by heat.) The work to be japanned is painted over with drying oil and lamp-black; when of a moderate dryness, it must be exposed to such a heat as will change the oil to black, with- out weakening its tenacity. The stove should not be too hot when the work is put into it, nor the heat increased too fast, else it will blister; the slower the heat is augmented, and the 528 J E E. J A P DictionARY OF MECHANICAL scIENCE. longer it is continued, provided it be restrained within the due degrees, the harder will be the japan. This kind of varnish requires no polish, as that which it receives from the heat when properly managed is sufficient. , Tortoise-shell Japan Ground, produced by heat, is valuable for its great hardness, and its beautiful appearance. Besides, it endures to be made hotter than boiling water without dam- age. It is made by means of a varnish prepared thus:–Take one gallon of good linseed oil, and of umber half a pound ; boil them together till the oil becomes brown and thick; strain it through a coarse cloth, and boil it again till it acquire a pitchy consistence, when it will be fit for use. Having prepared the varnish, clean well the iron or copper plate, or other pieces which are to be japanned, then lay ver- milion tempered with shell-lac warnish, or with drying oil diluted with oil of turpentine, very thinly, on the plates in- tended to imitate the more transparent parts of the tortoise- shell. When the vermilion is dry, brush the whole over with the black varnish, to a true consistence with oil of turpentine; and when it is set and firm, put the work into a stove, where it may undergo a very strong heat, for three weeks or a month, the longer the better. - This ground may be decorated with painting and gilding as other varnished surfaces. This is done after the ground has been hardened by the stove; but it should receive a second annealing with a more gentle heat, after it is finished. The method of Painting Japan-work. Japan work should be painted with colours in varnish; though for despatch, and in nice work where the freer use of the pencil is required, the colours are tempered in oil. But the oil should previously have a fourth part of its weight of gum animi; or, gum sand- arach, or gum mastich dissolved in it. When the oil is thus used, it is diluted with oil of turpentine, for the colours to lie evenly and thin. By this means, fewer of the polishing or upper coats of varnish become necessary. Water colours are in some instances laid on grounds of gold. These are best, when so used in their proper appear- ance, without any varnish over them; and they are also some- times managed to have the effect of embossed work. The colours thus employed for painting, are prepared with isin- glass size, corrected by honey or sugar-candy. The body of the embossed work which is raised, is not tinged with the exterior colour, but formed of strong gum water, thickened to a proper consistence by equal parts of bole Armenian and whiting. This gum is laid on the proper figure, and repaired when dry, and the whole may be then painted with the proper colours, tempered with the isinglass size, or shell-lac warnish. The manner of Varnishing Japan-work. The finishing of japan-work consists in the laying on and polishing the outer coats of varnish, as well in the pieces that have only one sim- ple ground of colour, as those that are painted. This is done with common seed-lac varnish, except where other methods are more expedient. The same reasons which decide as to the fitness of the varnishes, with respect to the colours of the ground, hold equally with regard to those of the painting. Where brightness is the most material point, and a tinge of yellow will injure it, seed-lac gives way to the whiter gums ; but where hardness, and a greater tenacity, are essential, the seed-lac must be adhered to; where both are so necessary, that reciprocally one should give way to the other, it is usual to adopt a mixed varnish. This mixed varnish is made of the picked seed-lac. The common seed-lac varnish, the most use- ful preparation of the kind, may be thus made. Take three ounces of seed-lac, put it into water, to free it from the sticks and filth intermixed with it. To do this, stir it about, and then pour off the water, adding fresh quantities, till it be freed from all impurities. Then dry it, powder it grossly, and put it, with a pint of rectified spirit of wine, into a bottle, of which it will not fill above two-thirds. Shake the mixture, place the bottle in a gentle heat, till the seed-lac is dissolved ; repeat the shak- ing, pour off all that is clear, strain the remainder, and put it in a close bottle. - In using seed-lac white warnish, the substance used in polishing should be itself white; but in other cases, the com- mon sorts of polishing dust may be used. The work to be warnished is placed near a fire, or stove, made perfectly dry : the varnish is then rubbed over with the brushes made for that purpose, beginning in the middle, and passing the brush over to one end, and then with another stroke passing it from the middle to the other end. No part should be twice passed over in forming one coat. When one coat is dry, proceed with a second, and so on six or seven times, till the varnish is suffi- ciently thick to bear the polish. In common cases, you may polish with a rag dipped in tripoli or rottenstone finely pow- dered; but before finishing, add a little oil with the powder: when the work is very bright, rub with oil alone, to clean all the powder off. It is an improvement in japan-work to harden the varnish by heat; and where metal forms the body, a hot stove is used. - JARGON, a precious stone found in Ceylon. See'ZIRcon. JASPER, in Mineralogy, a species of the clay genus, divid- ed into six sub-species. The Egyptian jasper exhibits two or more colours in concentric zones or bands, more or less regular, with interspersed spots or dendritic figures. It is brittle, and occurs in rolled pieces, which are mostly spherical. Before the blow-pipe it is infusible without addition, and on account of its beautiful colour and great hardness, it is used for similar purposes as the agate, The colours of the striped jasper are gray, green, yellow, and red; these are often found toge- ther, and arranged in striped and flamed delineations. It oc- curs in large beds in Saxony, and also in Siberia, where it is of a very beautiful kind. It admits of a high polish, and is used for purposes of ornament chiefly. The porcelain jasper generally exhibits but a single colour. Melted before the blow-pipe it is found to consist of silica, 60-75; alumina, 27:25; Inagnésia, 3:00; oxide of iron, 2.50; potash, 3-66; loss, 2.84. The common jasper is found in veins in primitive rocks. It is susceptible of a high polish. Opal jasper is found in nests in porphyry, near Tokay in Hungary, in the neighbourhood of Constantinople, and in some Siberian mountains. It is sup- posed to be the connecting link between jasper and opal, and is distinguishable by the liveliness of its colours, its superior lustre, and constant conchoidal fracture. JATROPHA, in Botany, a genus of the monoecia monadel- phia class and order. , Natural order of tricoccae. Euphorbiae, Jussieu. There are nine species, of which the most remarkable are: 1. The corcas, or English physic nut. 2. The gossypifolia, cotton-leaved jatropha. 3. The multifida, or French physic nut. 4. The manihot, or bitter cassada, has palmated leaves; the lobes lanceolate, very entire, and polished. 5. The janipha, or sweet cassada, has palmated leaves, with lobes very entire; the intermediate leaves lobed with a sinus on both sides. 6. The elastica, or hewan guianensis, with ternate leaves elliptic, very entire, hoary underneath, and longly petiolated. See CAOUT CHOUC. The root of bitter cassada has no fibrous or woody filaments in the heart, and neither boils nor roasts soft. The sweet cassada has all the opposite qualities. The bitter, however, may be deprived of its noxious qualities (which reside in the juice) by heat. Cassada bread, therefore, is made of both, thus: the roots are washed and scraped clean, then gra- ted into a tub : after this, they are put into a hair bag, and strongly pressed, to squeeze out the juice, and the meal is dried in a hot stone bason over the fire. Cassada roots yield a great quantity of starch, which the Brazilians export in little lumps under the name of tapioca. JAUN DICE, a disease created by a suffusion of bile, and determination thereof to the surface of the body, which is thence tinged yellow. JAW, Lock ED, a spasmodic contraction of the lower jaw, occasioned generally by some external injury affecting the tendons or ligaments. JAY, a beautiful bird of the genus Corvus. JEERS, or Jea Rs, an assemblage of tackles, by which the lower yards are hoisted up along the mast, or lowered down, as occasion requires; the former of which operations is called Swaying, and the latter Striking. In a ship of war, the jeers are usually composed of two strong tackles, each of which has two blocks, viz. one fastened to the lower mast-head, and the other to the middle of the yard. The two blocks which are lashed to the middle slings of the yard, are retained in this situation by means of two cleats, nailed on each side, whose arms enclose the ropes by which the blocks are fastened to the yard. The J E Tº J E 'I' * 529 DICTIONARY OF MECHANICAL SUIENCE, two ropes which communicate with these tackles lead down to the deck on the opposite side of the mast, according to the situation of the upper jeer-blocks. In merchant ships the jeers have usually two large single blocks on the opposite side of the mast-head, and another of the same size in the middle of the yard. The rope which communicates with these, passes through one of the blocks hanging on the mast-head, then through the block on the yard, and afterwards through the other hanging block on the mast. To the two lower ends of this rope, on the opposite sides of the mast, are fixed two tackles, each of which is formed of two double blocks, the lower one being hooked to a ring-bolt in the deck, and the upper one spliced or seized into the lower end of the great rope, above which is called the tye. By this contrivance the mechanical power of the tackle below is transmitted to the tye, which communicating with blocks on the yard, readily sways up, or lowers it, either by the effort of both jeers at once on the opposite sides of the mast, or by each of them separately, one after the other. They say a man is brought to the jeers, when going to be punished at the jeer-capstan. ' This is done in the following manner: a capstan-bar being thrust through the hole of the barrel, the offender’s arms are extended at full length cross-wise, and so tied to the bar, having sometimes a basket of bullets, or some other like weight, hanging by his neck. In this posture he continues till he be either brought to confess some plot or crime whereof he is suspected, or that he has suffered what he is sentenced to undergo at the discretion of the captain. - . JELLY, a food, medicine, or sweetmeat, prepared from the juice of unripe fruits, boiled to a proper consistency with sugar; or the strong decoctions of the horns, bones, or extremities of animals boiled to such a height as to be stiff and firm when cold, without the addition of any sugar. The jellies of fruits are cooling, Saponaceous, and acescent, and therefore are good as medicines in all disorders of the prima vide, arising from alkalescent juices, especially when not given alone, but diſuted with water. On the contrary, the jellies made from animal substances are all alkalescent, and are therefore good in all cases in which an acidity of the humours prevails. The alka- lescent quality of these is, however, in a great measure taken off, by adding lemon juice and sugar lemon to them. There were formerly a sort of jellies much in use, called compound jellies; these had the restorative medicinal drugs added to them, but they are now scarcely ever heard of. - JELLY Oat, a preparation of common oats, recommended by many of the German physicians in all hectic disorders, to be taken with broth of snails or cray fish. It is made by boiling a large quantity of oats, with the husk taken off, with some hartshorn shavings, and currants, together with a leg of veal cut in pieces, and with the bones all broken ; these are to be set over the fire with a large quantity of water, till the . whole is reduced to a sort of jelly, which, when strained and cold, is firm and hard. A few spoonfuls of this are to be taken every morning, diluted with a bason of either of the above- mentioned broths, or any other warm liquor. JELLY, in Chemistry. If we press out the juice of ripe cur- rants, and many other acid fruits, and let it remain in a state of rest, it partly coagulates into a tremulous soft substance. If we wash the coagulum with a small quantity of water, we obtain jelly approaching to a state of purity, and nearly colourless, un- less tinged by the peculiar colouring matter of the fruit; it has a pleasant taste, and a tremulous consistency. It is scarcely soluble in cold, but very soluble in hot water; and when the Solution cools, it again coagulates. When long boiled, it loses the property of gelatinizing by cooling. JESUITS, or the Society of Jesus, in Church History, a ce- prated religious order in the Romish Church, founded by Igna- tius Loyola, a Spaniard. To the three ordinary monastic vows of chastity, poverty, and obedience, they added a fourth, which was, to go wherever the pope should command. The order was abolished in 1773: but was lately restored by Pope Pius VII, the predecessor of the present pope, and re-established in Italy, Spain, and Switzerland. - JESUIT's Bark. See CINCHONA. 2. JET, a black inflammable substance of the bituminous kind, hard. than asphaltum, and susceptible of a good polish. It becomes electrical by rubbing, attracting light bodies like yellow amber. It swims on water, so that its specific gravity must be less than 1000; notwithstanding which it has been frequently confounded with the lapis obsidianus, the specific gravity of which, according to Kirwan, is no less than 1744. It also resembles cannel coal extremely in its hardness, receiv- ing a polish, not soiling the fingers, &c.; so that it has also been confounded with this. The distinction, however, is easily made betwixt the two; for cannel coal wants the electrical pro- perties of jet, and is likewise so heavy as to sink in water, its specific gravity being no less than 1273; whereas that of jet, as has already been said, is less than 1000. - - . . Mr. Magellan is of opinion, that the jet is a true amber, dif- fering from the yellow kind only in the mere circumstance of colour, and being lighter on account of the great quantity of bituminous matter which enters into its composition. When burning, it emits a bituminous smell. It is never found in strata or continued masses like fossil stones, but always in separate and unconnected heaps like the true amber. Great quantities of it have been dug in the Pyrenean mountains; also near Batalka, a small town of Portugal, and in Galicia, in Spain. It is found also in Ireland, Sweden, Prussia, Ger- many, and Italy. It is used, in making small boxes, buttons, bracelets, mourning jewels, &c. Sometimes also it is employed, in conjunction with proper oils, in making varnishes; when mixed with lime in powder, it is said to make very hard and durable cement. JET D’EAU, a French word signifying a fountain that throws up water to some height in the air. Jets and fountains, though in some situations conducive to picturesque beauty, are of little utility except in tropical cli- mates. But in the jet or formation of Hiero of Syracuse, the head of water is lower than the orifice, yet as the pressure is com- municated by a column of air, this jet d'eau may be considered of great utility in large works where its application is desired. This figure represents the machine, in which are two vessels, KL MN, and O P H Q R, close on all sides. A B is a tube having a funnel at the top, and it passes through the higher vessel without inter- fering with the fluid therein contained, being fixed or soldered air-tight at its - top and bottom. It passes likewise - through the top of the lower vessel, being soldered air-tight there also, and it reaches almost to the bottom of this vessel. This tube is open at both ends. S T is another tube similarly fixed, but in an inverted order, and it is also open at top and bottom. These two tubes support the upper vessel. A third tube G. F., is soldered into the top of the other vessel, and reaches al most to its bottom. This tube is open at both ends, but the orifice G is very small Fill the upper vessel with water to the height EN, Ee being its surface a little below T; stop the orifice G with the fin ger, and pour in water at A ; it will pass down B, and compress the air again into less room in O Q R. P. Whenever the - water in the lower vessel rises to C c, the air which formerly occupied the whole of the spaces OPQR and Ee LK, will now be contained in the spaces o Pe C and K Le E ; and its elasticity will be in equilibrio with the weight of the column of water, whose base is the surface Ee, and whose height is Ac: hence if your finger be now removed from the orifice G, the fluid will spout up through that tube as high as it is long, or equal to the altitude e H.; and while there is any water in the vessel KL MN, there will be a discharge through the orifice. . -- . ~~ The height of the water measured from the basin V AW to the surface of the water in the lower vessel, is always equal to the height measured from the top of the jet to the surface of the water in the vessel K LM. N.; and as the surface Beis constantly falling, and the water in the under vessel always rising, the T 530 # E w J O I DICTIONARY OF MECHANICAL | SCIENCE. height of the jet is perpetually decreasing, until it is shorter by the depth of KLM N, which is empty, added to the depth of O P Q R, which is continually falling; and so soon as the iet has fallen, thus low, it ceases to play. JETSAM, any thing thrown out of a ship being in danger of wreck, and by the waves driven to the shore. JETTE, the border made round the stelts under a pier, in certain old bridges, being the same with starling, consisting of a strong framing of timber filled with stones, chalk, &c. to preserve the foundations of the piers from injury. JETTY Head, a name usually given in the royal dock yards to that part of a wharf which projects beyond the rest; but more particularly the front of a wharf, whose side forms one of the cheeks of a dry or wet dock. JEWEL, any precious stone, or ornament beset with them. See D1 AMOND, RUBY, &c. - Jew ELs made a part of the ornaments with which the Jews, Greeks, and Romans, especially their ladies of distinction, adorned themselves. So prodigious was the extravagance of the Roman ladies in particular, that Pliny the elder says, he saw Lullio Paulina with an equipage of this kind, amounting, according to Dr. Arbuthnot's calculation, to £322,916. 13s. 4d. of our money. It is worthy of observation, that precious stones among the Romans and all the ancients were much scarcer, and consequently in higher esteem, than they are amongst us, since a commerce has been opened with the Indies. The ancients did not know how to cut and polish them to much perfection; but coloured stones were not scarce, and they cut them very well either hollow or in relief. When luxury had gained ground amongst them, the Romans hung pendants and pearls in their ears; and for this purpose, the ears of both sexes were frequently bored. See EARs. JEWEL-BLOCKS, in Shipping, two small blocks, which are suspended at the extremity of the main and fore top-sail-yards, by means of an eye-bolt driven from without into the middle of the yard-arm parallel to its axis. The use of these blocks is to retain the upper part of the top-mast studding-sails beyond the sheets of the top-sails, so that each of these sails may have its full force of action, which would be diminished by the encroachment of the other over its surface. The halliards, by which those studding-sails are hoisted, are passed through the jewel-block, whence, communicating with a block on the top- mast-head, they lead downwards to the top or decks, where they may be conveniently hoisted. JEWS, in Church History, the descendants of Judah the son of Jacob, and of the Israelites, commonly denominated the Twelve Tribes of Israel. This name was first given to those Jews who returned from the captivity of Babylon, because the tribe of Judah made the most conspicuous figure among them. The following is a summary of their religous creed: 1. That God is the creator and active supporter of all things. 2. That God is one, and eternally unchangeable. 3. That God is incorpo- real, and cannot have any material properties. 4. That God shall eternally subsist. 5. That God is alone to be worshipped. 6. That whatever has been taught by the prophets is true. 7. That Moses is the head and father of all contemporary doctors, and of all those who lived before, or shall live after him. 8. That the law was given by Moses. 9. That the law shall always exist, and never be altered. 10. That God knows all the thoughts and actions of men. 11. That God will reward the ob- servance, and punish the breach, of his law. 12. That the Messiah is to come, though he tarry a long time. 13. That there shall be a resurrection of the dead when God shall think fit. In England, in former times, the Jews and all their goods belonged to the chief lord where they lived. By stat. Edward I, the Jews, to the number of 15,000, were banished out of England; and never returned till Oliver Cromwell re-admitted them. When- ever any Jew shall present himself to take the oath of abjuration in pursuance of the 10 George III. c. 10, the words, upon the true faith of a Christian, shall be omitted. If Jewish parents refuse to allow their Protestant children a maintenance suit- able to their fortune, the Lord Chancellor, upon complaint, may make such order therein as he may think proper. - Jews' Harp, in Music, an instrument well known among the lower classes in this country, almost the only musical instru- ment made use of by the inhabitants of the island of St. Kilda. JIB, the foremost sail of a ship, being a large stay-sail extended from the outer end of the bow-sprit, prolonged by the jib-boom towards the fore-top-mast. head. In cutters and sloops the jib is on the bowsprit, and extends towards the lower mast-head. The jib is a sail of great command with any side wind, but especially when the ship is close-hauled, or has the wind upon her beam; and its effort in casting the ship, or turning her head to leeward, is very powerful and of great utility, particularly when the ship is working through a narrow channel.—Flying Jib, a sail sometimes set upon a boom, rigged out beyond the jib-boom.—Middle Jib, a similar sail, some- times set between the two preceding, being extended from the end of the jib-boom, while the inner jib-tack is near half way down or on the boom. - Ji B-Boo M, is a continuation of the bowsprit forward, being run out from the extremity in a similar manner to a top-mast on a lower-mast, and serving to extend the bottom of the jibs and the stay of the fore-top-gallant-mast. It is usually attached to the bowsprit by means of two large boom-irons, or by one boom-iron and a cap on the outer end of the bowsprit, or by a cap without, and a strong lashing within, instead of a boom- iron, which is generally the method of securing it in small merchant ships: when it ean be drawn in upon the bowsprit as occasion requires, which is frequently practised when the ship enters a harbour, where it might very soon be broken or carried away, by the vessels which are moored therein or pass- ing by under sail.—Flying Jib-Boom, is a boom extended beyond the preceding by means of two boom-irons, and to the fore- most end of which the tack of the flying-jib is hauled out. JIGGER, a machine consisting of a piece of rope about five feet long, with a block at one end, and a sheave at the other, used to hold on the cable when it is heaved into the ship by the revolution of the windlass. The jigger is particularly use- ful when the cable is either slippery with mud or ooze, or when it is stiff or unwieldy; in both of which cases it is very difficult to stretch it back from the windlass by hand, which however is done with facility and expedition by means of the jigger, in the following manner: the end of the rope to which the sheave is fastened by a knot, is passed round the cable' close to the windlass, and the hind part of the rope coming over the sheave, is stretched aft by means of another rope passing through the jigger-block. As soon as the last rope is extended, the turn of the former about the cable is firmly retained-in its position by the compression of its hind part under the sheave, acting upon what may be called the neck of the jigger. Fleet JIGGER, a term used by the man who holds on the jig- ger, when, by its distance from the windlass, it becomes neces- sary to fleet or replace it in a proper state of action, for as the cable continues to be heaved into the ship, it is evident that the jigger, which is fastened on a particular part thereof, stretching it back, will be removed further aft, by every turn of the windlass, and the effort of the jigger will be lessened in proportion to its distance from the windlass; accordingly, when the man gives the above notice, another at the windlass immediately fixes his handspike between the deck and the cable, so as to jam the latter to the windlass, and prevent it from running out till the jigger is replaced near the windlass. JIGGER-Tackle, a light small tackle consisting of a double and a single block, and used by seamen on sundry occasions. JOBBER, a person who undertakes jobs, or small pieces of work. In some statutes, jobber is used for a person who buys and sells for others, and is equivalent to broker. Hence jobbing, the business of a jobber. tº º Stock JoBBING denotes the practice of trafficking in the pub- lic funds, or of buying and selling stock with a view to its rise or fall. The term is commonly applied to the illegal practice of buying and selling stock for time, or of accounting for the dif- ferences in the rise or fall of any particular stock for a stipu- lated time, whether the buyer or seller be possessed of any such real stock or not. See Stock Broker. º º JOINERY, the art of working in wood, or of fitting various pieces of timber together. It is called by the French small work, to distinguish it from carpentry, which is employed about large works. See ARCHITECTURE, BUILDING, and House. JOINT, in general, denotes the juncture of two or more things. The joints of the human body are called by anatomists J O N J U D DICTIONARY OF MECHANICAL SCIENCE. 531 articulations. See ANATOMY. The suppleness to which the joints may be brought by long practice, from the time of infancy, is very surprising. Every common posture-master shews us a great deal of this; but one of the most wonderful instances we ever had of it, was in a person of the name of Clark, and famous for it in London, where he was commonly known by the name of Clark the posture-master. This man had found the way, by long practice, to distort many of the bones, of which nobody before had ever thought it possible to alter the position. " He had such an absolute command of his muscles and joints, that he could almost disjoint his whole body. So that he once imposed on the famous Mullens by his distortions in such a manner, that he refused to undertake his cure ; but, to the amazement of the physician, no sooner had he given over his patient, than he saw him restore himself to the figure and condition of a proper man, with no distortion about him. . Joi NT Actions, in personal actions, several wrongs may be joined in one writ; but actions founded upon a tort and a contract cannot be joined. - - Joint and Several, an interest cannot be granted jointly and severally. Joint Lives, lease for years to husband and wife, if they or any issue of their bodies should so long live, has been adjudged so long as either the husband, wife, or any of their issue, should live. - : Joi NT Stock Companies, are trading associations with a stock consisting of many shares, in which the individuals gain or lose in proportion to their shares. For very large un- dertakings, such as the making of a canal or building a bridge, where the capital of a few men is inadequate, the union of many individuals may be necessary and sometimes profitable. In general, joint stock companies are not profitable to the indivi- dual shareholders, although they may be beneficial to the per- Sons who are paid for managing the concern on behalf of the body at large. It is a common delusion, that the share-holder is not responsible beyond the amount of his share, but except it be a corporate body, every farthing of his property is liable for all the debts and obligations of the company. To put a stop to delusive schemes, which led many persons to their ruin, the statute of 16 Geo. I. c. 18, was enacted, commonly called the bubble act; it has, however, been evaded, or allowed to re- main inoperative. Many joint stock companies obtain an act of parliament, by which they may sue or be sued in the name of their chairman, secretary, or any of their members, which they otherwise could not do, as it would be necessary in all the records and pleadings to recapitulate the names and desig- nations of all the shareholders, which in some cases would be impossible, and in all cases extremely tedious and expensive. Joi NT Tenants, are those that hold lands or tenements by one title, without partition. The creation of an estate in joint tenancy depends on the wording of the deed or devise by which the tenant claims title, and cannot arise by act of law. If any estate be given to a plurality of persons, without adding any restrictive, exclusive, or explanatory words, this makes them immediately joint tenants in fee of the lands. If there be two joint tenants, and one release the other, this passes a fee without the word heirs, Joint tenants may make partition; the one party may compel the other to make partition, which must be by deed ; that is to say, all the parties must by deed actually convey and assure to each other the several estates which they are to take and enjoy severally and separately; joint tenants must jointly implead and be jointly impleaded with others. If one joint tenant refuse to join in an action, he may be summoned and severed ; but if the person severed die, the writ abates in real actions, but not in personal and mixed actions. - JOINTURE, in Law, generally signifies a settlement of lands and tenements, made on a woman in consideration of marriage. . JOISTS, or Joysts, in Architecture, those pieces of timber framed into the girders and summers, on which the boards of the floor are laid. - * JONK, Jonque, or JUNK, a kind of small ship, very com- mon in the East Indies. These vessels are about the size of fly-boats, and differ in the form of their building, according to the different methods of naval architecture used there. The sails are frequently made of mats, and the anchors of wood. JOURNAL, a sort of diary, or daily register of the ship's course and distance, the winds and weather, together with a general account of whatever is material to be remarked in the period of a sea voyage, such as the shifting, reducing, or enlarging the quantity of sail, the condition of the ship and her crew, the discovery of other ships or fleets, lands, shoals, breakers, soundings, &c. • * w Journal, a day book, register, or account of what passes daily. See Book-Keeping. & - JOURNEYMAN, properly one who works by the day only; but the word is now used for any one who works under a master, either by the day, the year, or the piece. - JOY, in Ethics, is that passion which is produced by love, regarding its object as present, either immediately or in pros- pect, in reality or imagination. . The operation of joy some- times effects the functions of the body, by increasing the secretion of perspiration and some others. - JUBILEE, a time of public and solemn festivity among the ancient Hebrews. This was kept every fiftieth year; and began about the autumnal equinox. At this time all slaves were released, all debts annihilated, and all lands, &c. however alienated, were restored to their first owners. During this whole year all kind of agriculture was forbidden, and the poor had the benefit of the harvest, vintage, and other productions of the earth.-The Christians, in imitation of the Jews, have likewise established jubilees, which began in the time of pope Boniface VIII. in the year 1300, and are now practised every twenty-five years; but these relate only to the pretended for- giveness of sins, and the indulgences granted by the church of Rome. JUDGMENT, among Logicians, a faculty, or rather act, of the human soul, whereby it compares its ideas, and perceives their agreement or disagreement. See Logic and META- PHYSICS. JUDGMENT, in Law, is the sentence pronounced by the court upon the matter contained in the record. Judgments are of four sorts. First, where the facts are confessed by the parties, and the law determined by the court; as in case of judgment upon demurrer. Secondly, where the law is admitted by the parties, and the facts disputed; as in the case of judgment or verdict. Thirdly, where both the facts, and the law arising thereon, are admitted by the defendant; which is the case of judgment by confession or default; or, lastly, when the plain- tiff is convinced that either fact, or law, or both, are insufficient to support his action, and therefore abandons or withdraws his prosecution; which is the case in judgments upon a monsuit or traacit. The judgment, though pronounced or awarded by the judges, is not their determination or sentence, but the determination and sentence of the law. It is the conclusion that naturally and regularly follows from the pre- mises of law and fact, which stands thus: Against him who hath rode over my corn, I may recover damages by law; but A hath rode over my corn, therefore I shall recover damages against A. If the major proposition be denied, this is a demurrer in law; if the minor, it is then an issue of fact; but if both be confessed or determined to be right, the conclusion or judgment of the court cannot but follow; which judgment or conclusion depends not therefore on the arbitrary caprice of the judge, but on the settled and invariable principles of jus- tice. The judgment, in short, is the remedy prescribed by law for the redress of injuries; and the suit or action is the vehicle or means of administering it. What that remedy may be, is indeed the result of deliberation and study to point out; and therefore the style of the judgment is, not that it is decreed or resolved by the court, for then the judgment might appear to be their own; but, “it is considered,” consideratum est curiam, that the plaintiff do recover his damages, his debt, his pos- session, and the like ; which implies, that the judgment is none of their own; but the act of law, pronounced and declared by the court, after due deliberation and inquiry. See Black- stone's Comment. iii. 396. . - JUDGMeNT, in criminal cases, is the next stage of prosecution, after trial and conviction are passed, in such crimes and misde- meanors as are either too high or too low to be included within 532 J U D 'J U I DICTIONARY OF MECHANICAL SCIENCE. the benefit of clergy.” For when, upon a capital charge, the jury have brought in their verdict “guilty” in the presence of the prisoner, he is either immediately, or at a convenient time soon after, asked by the court, if he has any thing to offer why judg- ment should not be awarded against him? And in case the ‘defendant be found guilty of a misdemeanor, (the trial of which may, and does usually, happen in his absence, after he has once appeared,) a capias is awarded and issued, to bring him in to receive his judgment; and if he absconds, he may be prosecuted even to outlawry. But whenever he appears in person, upon either a capital or inferior conviction, he may at this period, as well as at his arraignment, offer any exceptions to the indictment, in arrest or stay of judgment; as, for want of sufficient certainty in setting forth either the person, the time, the place, or the offence. And if the objections be valid, the whole proceedings shall be set aside: but the party may be indicted again; and even may take notice, 1. That none of the statutes of jeofails, for amendment of errors, extend to indict- ments, or proceedings in criminal cases; and therefore a defec- tive indictment is not cited by a verdict, as defective plead- ings in civil cases are. 2. That in favour of life, great strict- ness has at all times been observed, in every point of an indict- ment. Sir Matthew Hale indeed complains, “that this strict- ness is grown to be a blemish and inconvenience in the law and the administration thereof; for that more offenders escape by the ever-easy ear given to exceptions in indictments, than by their own innocence ; and many times gross murders, burglaries, robberies, and other heinous and crying offences, remain unpunished by these unseemly niceties, to the reproach of the law, to the shame of the government, to the encourage- ment of villany, and to the dishonour of God.” And yet, not- withstanding this laudable zeal, no man was more tender of life than this truly excellent judge.—A pardon also may be pleaded in arrest of judgment; and it has the same advantage when pleaded here as when pleaded upon arraignment; viz. the saving the attainder, and, of course, the corruption of blood; which nothing can restore but parliament, when a pardon is not pleaded till after sentence. And certainly, upon all accounts, when a man hath obtained a pardon, he is in the right to plead it as soon as possible. See PARDon. Praying the benefit of clergy, may also be ranked among the motions in arrest of judgment. . See BeNefit of CLERGY. If all the resources fail, the court must pronounce that judg- ment which the law hath annexed to the crime. Of these, some are capital, which extend to the life of the offender, and consist generally in being hanged by the neck till dead; though in very atrocious crimes other circumstances of terror, pain, or disgrace, are superadded, as, in treasons of all kinds, being drawn or dragged to the place of execution: in high treason committed by a female, the judgment is, to be burned alive. But the humanity of the English nation has authorized, by a tacit consent, an almost general mitigation of such parts of these judgments as 'savour of torture or cruelty : a sledge or hurdle being usually allowed to such traitors as are condemned to be drawn; and there being very few instances (and those accidental or by negligence) of any person’s being embowelled or burned, till previously deprived of sensation by strangling. Some punishments consist in exile or banishment, by abjura- tion of the realm, or transportation beyond the seas; others in loss of liberty, by perpetual or temporary imprisonment. Some extend to confiscation by forfeiture of lands or moveables, or both, or of the profits of lands for life; others endure a disabi- ſity of holding offices or employments, being heirs, executors, and the like. Some, though rarely, occasion a mutilation or dismembering, by cutting off the hand or ears : others fix a lasting stigma on the offender, by slitting the nostrils, or brand- ing in the hand or face. Some are merely pecuniary, by stated or discretionary fines; and, lastly, there are others that con- sist principally in their ignominy, though most of them are mixed with some degree of corporeal pain, and these are inflicted chiefly for such crimes as either arise from indigence, or render even opulence disgraceful; such as whipping, hard labour in the house of correction, the pillory, the stocks, and the ducking-stool. Disgusting as this catalogue may seem, it will afford pleasure to a British reader, and do honour to the British laws, to compare it with that shocking apparatus of death and torment, to be met with in the criminal codes of almost every other nation in Europe. And it is moreover one of the glories of our laws, that the nature, not always the quan- tity or degree, of punishment is ascertained for every offence; and that it is not left in the breast of any judge, nor even of a jury, to alter that judgment which the law has beforehand ordained for every subject alike, without respect of persons. For if judgment were to be the private opinions of the judge, men would then be slaves to their magistrates, and would live in society without knowing exactly the conditions and obliga- tions which it lays them under. And, besides, as this prevents oppression on the one hand, so on the other, it stifles all hopes of impunity or mitigation with which an offender might flatter himself, if his punishment depended on the humour and discre- tion of the court. Whereas, where an established penalty is annexed to crimes, the criminal may read their certain con- sequence in that law, which ought to be the unvaried rule, as it is the inflexible judge of his actions. * JUGLANS, in Botany, Walnut Tree, a genus of the monoecia polyandria class and order. Natural order of amentaceae. Terebintaceae, Jussieu. There are eight species, of which J. regia, common walnut, is a very large and lofty tree, with strong spreading boughs. There are several varieties, but they all vary again when raised from the seed, and nuts from the same tree will produce different fruit. The wood is in great request, on account of its fine grain and colour. The husks and leaves being macerated in warm water, and the liquor poured on grass walks and bowling-greens, will infallibly kill the worms, without endangering the grass. JUGULARES, in Natural History, an order of fishes accord- ing to the Linnaean system. They have their ventral fins situated before the pectoral fins, and as it were under the throat. Their hody is sometimes covered with scales, and sometimes not. With a very few exceptions, they have spines in the dorsal and anal fins, and their gills have bony rays. Of this order are the following genera; blenius, cally onumus, gadus, kurtels, tra- chinus, uranoscopus. - - JUICE, denotes the sap of vegetables, or the liquors of animals. See ANAToMY, BlooD, PLANTS, SAP, &c. The juices of several plants are expressed, to obtain their essential salts, and for several medicinal purposes, with intention either to be used without further preparation, or to be made into syrups and extracts. The general method of extracting these juices is, by pounding the plant in a marble mortar, and then by put- ting it into a press. Thus is obtained a muddy and green liquor, which generally requires to be clarified, as we shall soon observe. Juices which are not acid, and not very mucila- ginous, are spontaneously clarified by rest and gentle heat.— Fermentation is also an effectual method of clarifying juices which are susceptible of it; for all liquors which have fer- mented, clarify spontaneously after fermentation. . The juices, especially before they are clarified, contain almost all the same principles as the plant itself, because in the operation by which they are extracted, no decomposition happens, but every thing remains, as to its nature, in the same state as in the plant. Most vegetable juices coagulate when they are exposed to the air, whether they are drawn out of the plant by wounds, or naturally run out; though what is called naturally running out, is generally the effect of a wound in the plant, from a sort of canker, or some other internal cause. Different parts of the same plant yield different juices. Among those juices of vegetables which are clammy, and readily coagulate, there are some which readily break with a whey. The great wild lettuce, with the smell of opium, yields the greatest plenty of milky juice of any known British plant. These juices, as well as the generality of others which bleed from plants, are white like milk, but there are some of other colours. The juice of the great celandine is of a fine yellow colour; it flows from the plant of the thickness of cream, and soon dries into a hard cake, without any whey separating from it. Another yellow juice is yielded by the seed-vessels of the yel- low centaury in the month of July, when the seeds are full-grown. This is very clammy; it sobn hardens altogether into a cake, without any whey separating from it. Another kind of juices, very different from all these, are those of a gummy nature. Some of these remain liquid a long time, and are not to be J U N “J U N DICTIONARY OF MECHANICAL SCIENCE. °533 dried without the assistance of heat; and others very quickly harden of themselves, and are not inflammable. Some plants yield juices which are manifestly of an oily nature. These, when rubbed, are not at all of a clammy nature, but make the fingers glib and slippery, and do not at all harden on being exposed to the air. If the stalk of elecampane be wounded, there flows out an oily juice swimming upon a watery one. . The stalks of the hemlock also afford a similar oily liquor swim- ming upon the other; and in like manner the white mullein, the berries of ivy, the bay, juniper, and the fruit of the olive, when wounded, shew their oil floating on the watery juice. Some of these oily juices, however, harden into a kind of resin. JULIAN CALENDAR, Epoch—Period—Year, &c. See the re- spective articles. - - JULY, the seventh month of the year; during which the sun enters the sign Leo. The word is derived from the Latin Julius, the surname of Caius Julius Caesar, the dictator, who was born in it. Marc Antony first gave this month the name July, which before was called Quintilis, as being the fifth month of the year in the old Roman kalendar established by Romulus, which began in the month of March. For the same reason, August was called Sextilis; and September, October, Novem- ber, and December, still retain the name of the first rank. On the 10th day of this month the dog-days are commonly supposed to begin; when, according to Hippocrates and Pliny, the sea boils, wine turns sour, dogs go mad, the bile is increased and irritated, and all animals decline and languish. . The Kalendar of Animated Nature round London for this month. The cuckoo loses her voice; the stone curlew whis- tles occasionally late at night; the golden-crested wren chirps; the quail calls; the cuckoo-spit or frog-hopper abounds; young frogs migrate; the great horse-fly appears; and young par- tridges fly. - * , ; - In the Kalendar of Vegetable Nature, we see enchanter's 'nightshade, lavender, pinks, and carnations, in bloom. Rasp- berries and gooseberries are now ripe, potatoes are in flower, and asparagus in berry, and truffle may now be dug up in com- mons and forests. But for the various productions of this sea- son, the reader must consult works which give them in detail. JUMP, in Mining, is one among the numerous appellations, which the dislocations of the strata have received from the practical miners of different districts. The process or convul- sion of nature, is frequently called “The heaving of the lode,” and exhibits a phenomenon in mining, which the science of mineralogy has not yet been able to solve. JUMPER. This is a name given to a long iron tool with a steel chisel-like point, much used in mines, for drilling or boring of holes in rocks which are to be blasted with gun- powder. Some have confounded this instrument with another, generally called a Gad. The Gad, however, is a different tool, having no connexion with the holes bored to be used in the blasting process. . In some places, Jumper and Borer are terms of synonymous import, applied promiscuously to the same tool. The term Jumper is also given to a Christian sect well known in Wales, and remarkable for their eccentricity. JUNCI LAPIDEI, in Natural History, the name given by authors to a species of fossil coral of the tabularia kind, and :composed of a congeries of small tubules, which are usually round and striated within. JUNCTURE, in Oratory, is a part of composition particu- larly recommended by Quintilian, and denotes such an atten- tion to the nature of the vowels, consonants, and syllables, in the connexion of words, with regard to their sound, as will render their pronunciation most easy and pleasant, and best promote the harmony of the sentence. Thus, the coalition of two vowels occasioning a hollow and obscure sound, and like- wise of some consonants rendering it harsh and rough, should be avoided; nor should the same syllable be repeated at the beginning and end of words, because the sound becomes hereby harsh and unpleasant. , JUNCUS, the Rush, a genus of plants belonging to the hexandria class; and in the natural method ranking under the fifth order Tripetaloideae. See BotANY. - JUNE, the sixth month of the year, during which the sun enters the sign Cancer. In this month is the summer solstice. See CANCER, the Crab, (page 142,) for the astronomical and 55. physical relation of June. The word is from Junius or 3 Junone, for the goddess says in Ovid, Junius à nostro nomine nomen habet. There are, however, two other topics that solicit our attention here, and we shall therefore develop them in the sequel of this article. - t 1. Kalendar for this month, in the south of Britain. In Ani- mated Nature, during the first week, we see the wasp, and several species of the bee and butterfly tribes, with the hedge-sparrow and fly-catcher. In the seednd week, the burnet moth and forest fly shew themselves, and bees swarm. In the third week, flies, butterflies, moths, beetles, and other insects appear. In the fourth week, insects abound, singing birds begin to retire to the woods, and lose their song. 2. The Kalendar of Vegetable Nature round London. In the first week, water-lilies flower, and numerous other plants. In the second week, the vine, raspberry, and elder are in flower. Scotch roses, broom, and nettle flower; and wheat is now in the ear. In the third week, a great variety of plants flower, also many of the pasture grasses and late wheats. In the fourth week, currants, ripen, strawberries abound, young shoots of trees and shrubs attain their length; oats and barley flower, &c.—For particulars which relate to the kitchen gar- den, to fruit trees, to flowers, to pleasure grounds, and shrub- beries, we must refer the reader to treatises written professedly on these subjects. - - - - JUNGERMANNIA, in Botany, a cryptogamia genus of plants, very numerous in species, as well as distinct in cha-. racter. It was thus named by Ruppius and Micheli, who have been followed by all botanists since their day, in honour of Lewis Jungermann, professor of botany at Altdorf, and after- wards at Giessen, in the early part of the seventeenth century. The plants of this genus have hitherto been but inaccurately defined. - - - * JUNGIA, in Botany, so named by the younger Linnaeus, in memory of Joachim Jungius, a learned German botanist, of the seventeenth century. - JUNIPA, in Botany, the name of a tree of the Caribbee Islands, and some other places, to which peculiar properties are ascribed. The fruit is said to yield a juice as clear as water, which communicates a fine purple dye, but being rubbed twice on the same spot, the purple gives place to black. This singular tincture, according to report, cannot be got out by soap or any other method of cleansing, and yet, after about mine or ten days, the colour wholly disappears of its own accord. The same authors who vouch for the above properties, also assert, that hogs and parrots feeding on this fruit, have their flesh and fat all tinged throughout of a violet colour. - JUNIPERUS, in Botany, Juniper Tree, a genus of the dioe- cia monadelphia class and order. Natural order of coniferae. There are twelve species: some of these are lofty handsome trees; but the common juniper is a low shrub, seldom more than three feet in height. The female flowers are succeeded by roundish berries, at first green, and when ripe of a dark purple colour. They continue on the bush two years, and are sessile in the axil of the leaves. Juniper is common in all the northern parts of Europe. The berries have a strong smell; and a warm pungent sweet taste, followed by a bitterish one. JUNK, any remnants or pieces of old cable, which are usu- sally cut for the purpose of making Points, MATs, GAskets, SENNIT, &c. which see. JUNO. Under the article Astronomy, a few observations were made on this planet, to which we now make the follow- ing additions. Juno is situated between the orbits of Mars and Jupiter, was discovered by Mr. Harding at the observatory of Lilienthal, near Bremen, on the evening of the first of Septem- ber, 1804. While this astronomer was forming an atlas of all the stars, as far as the eighth magnitude, which are near the orbits of Ceres and Pallas, he observed, in the constellation Pisces, a small'star of the eighth magnitude,which was not men- tioned in the “Histoire Celeste” of La Lande; and being ignorant of its longitude and latitude, he put it down in his chart as nearly as he could estimate with his eye. Two days afterwards the star disappeared, but he perceived another which he had not seen before, resembling the first in size and colour, and situa- ted a little to the south-west of its place. He observed it again on the 5th of September, and finding that it had moved a little 6 U *.*.*.*.*.* * * * * * * * * iſ iſ S J U R farther to the south-west, he concluded that this star belonged to the }l inetar 's Štem, - -- . . . . . . . . . . . . . . . . * * * * * ” The .# 'of a reddish colour; and is free from that nebulbsity which surrounds Pallas. Its diameter, and its mean distance, are less than those of the other new planets. It is distinguished from all other planets by the great eccentricity of is orbit; and the effect of this is so extremely sensible, that it passes over that half of its orbit, which is bisected by its perihelion, in half the time that it employs in describing the ºther half, which is farther from the sun. From the same cause, its greatest distance from the sun is double the least distance, the difference between the two distances being about 127 millions of miles. Though there is no nebulous appearance around the planet Juno, yet it appears, from the observations of Schroeter, that it must have an atmosphere more dense than that of any of the old planets of the system. A very remarkable variation in the brilliancy of this planet has been observed by this astronomer. He attributes it chiefly to changes that are going on in its atmosphere, though he thinks it not improbable that these changes may arise from a diurnal rotation performed in 27 hours. The following elements were calculated by Buckhardt. Mean longitude, 31st Dec. 1804, noon . . . . . . . . . . I* 12° 17' 23" Place of ascending node . . . . . . . . . . . . . . . . . . . . 5° 21° 6' 0" Place of perihelion in 1805. . . . . . . . . . . . . . . . . . . . Is 29° 49' 23'ſ Eccentricity . . . . . . ... . . . . . . . . . . . . . . . . . . . . . . . . 0.25096 . . . . Inclination of orbit.... . . . . . . . . . . . . . . . . . . . . . . 21° 0' . . . . . . Ditto. . . . . . . . . . . e e e s e o is e º 'º º e s e º e º sº e º tº ... . . . . 13° 4'...... Meän distance. . . . . . . . ... . . . . . . . . . . . . . . . . . . . . . 2.067 . . . . . * Diameter in English miles, according to Schroeter 1425 . . . . . . Apparent mean diameter, as seen from the earth, - according to Schroeter.' . e e º s a e g º e e º e º a s e º a º JUPITER, among Alchemists, signifies the philosopher's gold. The gentlemen of this profession apply, every, thing to their art which the mythologists mention of the god Jupiter, asserting that the ancient fables are only to be understood in a figurative sense. - JUPITER, and his Satellites. See ASTRONOMY. d JURATS, magistrates in the nature of aldermen, for the go- vernment of several corporations. JURIES, in Common Law, consist of twelve or twenty-four men, sworn to inquire into facts, and declare the truth, upon such evidence as shall appear before them. Trial by jury is very ancient in this country. It seems to have been coeval with the existence of its civil government; and Some authors have endeavoured to trace their establishment up so high as the ancient Britons. It is certain that while the Saxons held dominion among us, juries were well known, and some have ascribed their origin to Woden, their great legislator and cap- tain. Juries are, in these kingdoms, the Supreme judges in all courts and in all causes, in which either the life, property, or reputation, of any man is concerned. This is the distinguish- ing privilege of every Briton, and one of the most glorious advantages of our constitution; for as every one is tried by his peers, the meanest subject is as safe and as free as the greatest. See the article TRIAL. JURISDICTION, a power or authority which a man has to do justice in cases of complaint made before him. There are two kinds of jurisdiction, the one ecclesiastical, the other secular. Secular Jurisdiction, belongs to the king and his justices or delegates. The courts and judges at Westminster have jurisdiction all over England, and are not restrained to any county or place; but all other courts are confined to their par- ticular jurisdictions; the first is tenere placita, to hold pleas, and the plaintiff may sue either there or in the king's courts. An- other is the cognizance of pleas, where a right is invested in the lord of the franchise to hold pleas; and is the only person that can take advantage of it, by claiming his franchise. The third sort is an exempt jurisdiction, as where the king grants to some city, that the inhabitants shall be sued within their city, and not elsewhere, though there is no jurisdiction that can withstand a certiorari to the superior courts. IEcclesiastical JURIs Diction, belongs to bishops and their deputies. Bishops, &c, have two kinds of jurisdiction; the one internal, which is exercised over the conscience in things purely spiritual; and this they are supposed to hold immediately of rule of equity. God... The other is , contentious, which is a privilege some princes have given them of terminating disputes between ecclesiastics and laymen. . . . . . . . . . * * * JURISPRUDENCE, the science of what is just or unjust; or the knowledge of laws, rights, Gustoms, statutes, &c. neces- sary for the administration of justice. See LAw. : JUROR, JURATOR, in a legal sense, is one of those twenty- four or twelve men who are sworn to deliver truth upon such evidence as shall be given them touching any matter in ques- tion. The punishment of petty jurors attainted of giving a verdict contrary to evidence, willingly, is very severe. . JURY, a certain number of men sworn to inquire into and try a matter of fact, and to declare the truth upon such evi- dénce as shall appear before them. . . JURY MAST, a temporary or occasional mast, erected in a ship in the place of one that has been carried away by tempest, battle, &c. Jurymasts are sometimes erected in a new ship, to navigate her down the river, or to a neighbouring port, where her proper masts are prepared for her. JUSTICE, in a moral sense, is one of the four cardinal virtues, which gives every person his due. Civilians distin- guish justice into two kinds, communicative and distributive. The former establishes fair dealing in the mutual commerce between man and man; and includes sincerity in our discourse, and integrity in our dealings. The effect of sincerity is mutual confidence, so necessary among the members of the same com- munity; and this mutual confidence is sustained and preserved by the integrity of our conduct. Distributive justice is that by which the differences of mankind are decided, according to the The former is the justice of individuals; the latter, of princes and magistrates. Fidelity and truth are the foundation of justice. As to be perfectly just is an attribute of the Divine nature—to be so to the utmost of our ability, is the glory of man. * ... • * * - - * * Justice, is also an appellation given to a person deputed by the king to administer justice to his subjects; whose autho- rity arises from his deputation, and not by right of magistracy. Of these justices there are various kinds in England, viz. Chief Justice of the Court of King's Bench, is the capital jus- tice of Great Britain, and is a lord by his office. His business . is chiefly to hear and determine all pleas of the crown; that is, such as concern offences against the crown, dignity, and peace of the king; as treason, felonies, &c. The officer was formerly not only chief justice, but also chief baron for the exchequer, and master of the court afterwards. He usually sat in the king's palace, and there executed that office formerly per- formed per comitem palatii; he determined in that place all the differences happening between the barons and other great men. He had the prerogative of being vice-regent of the kingdom whenever the king went beyond sea, and was usually chosen to that office out of the prime nobility; but his power was reduced by king Richard I. and king Edward I. His office is now divided, and his title changed from capitalis Anglea, justi- ciarius, to capitalis justiciarius ad placita coram rege tenenda, or, capitalis justiciarius banci regii. - t Chief Justice of the Common Pleas, he who with his assistants hears and determines all causes at the common law; that is to say, all civil causes between persons, as well personal as real; and he is also a lord by his office. • . Justices of Assize, were such as were wont by special com- mission to be sent to this or that county to take assize for the ease of the subjects. For, whereas these actions pass always by jury, so many men might not without great damage and charge be brought up to London; and therefore justices, for this purpose, by commissions particularly authorized, were sent down to them. These continue to pass the circuit by two and two twice every year through all England, except the four northern counties, where they go only once, despatching their several businesses by several commissions, for they have one commission to take assizes, another to deliver gaols, and another of oyer and terminer. In London and Middlesex a court of general gaol delivery is held eight times in the year. * , All the justices of peace of any county wherein the assizes are held, are bound by law to attend them, or else are liable to a fine, in order to return recognizances, &c. and to assist the judges in such matters as lie within their knowledge and juris- J U S J U S" DICTIONARY of MECHANICAL scIENCE diction; and in which some of them have been probably con- cerned by way of previous examination. See Assizes and JURY. Justices in Eyre, (justiciarii itinerantes or errantes,) were those who were anciently sent with commission into divers counties to hear such causes especially as were termed pleas of the crown; and that for the ease of the subject, who must else have been hurried to the courts of Westminster, if the causes were too high for the county courts. According to some, these justices were seat once in seven years; but others suppose that they were sent oftener. Camden says, they were insti- tuted in the reign of king Henry II. A.D. 1184; but they appear to be of an older date. They were somewhat like our justices of assize at this day, though for authority and manner of pro- ceeding very different. - - Justices of Gaol Delivery, those commissioned to hear and determine causes appearing to such as for any offence are cast | into prison. Justices of gaol delivery are empowered, by the common law, to proceed upon indictments of felony, trespass, &c. and to order execution or reprieve, and they have power to discharge such prisoners as upon their trials shall be ac- quittéd; also all such against whom, on proclamation made, no evidence appears to indict; which justices of oyer and ter- miner, &c. may not do. . . º - Justice of Nisi Prius, are now the same with justices of assize. It is common adjournment of a cause in the Common Pleas to put it off to such a day. Nisi Prius justiciarii venerant ad eas partes ad capiendes assizes: from which clause of adjourn– ment, they are called justices of nisi privs, as well as justices of assize, on account of writ, and actions they have to deal in. Justices of Oyer and Terminer, were justices deputed on some special occasions to hear and determine particular causes. The commission of oyer and terminer is directed to certain per- sons upon any insurrection, heinous demeanour, or trespass committed, who must first inquire, by means of the grand jury or inquest, before they are empowered to hear and determine by the help of the petit jury. It was formerly held that no ºmmº-º-º-º-ºm-ºsmº-s *mmimºssam K A. L. K, or k, the tenth letter of our alphabet; as a number de- notes 250, and with a line over it, 250,000. - KAEMPFERIA. There are two species, viz. K. galangale; and K. rotunda, natives of the East Indies. KALEIDOSCOPE, an instrument for creating and exhibit- ing an infinite variety of beautiful forms, and constructed in such a manner as either to please the eye, by an ever-varying. succession of splendid tints and symmetrical forms, or to enable the observer to render permanent such as may appear most appropriate for any of the numerous branches of the ornamental arts. This instrument, the invention of Dr. Brewster, in its most common form, consists of a tin tube, containing two reflecting surfaces inclined to each other, at any angle which is an ali- quot part of 360°. The reflecting surfaces may be two plates of glass, plain or quicksilvered, or two metallic surfaces, from which the light suffers toual reflection. The plates should vary in length according to the ſocal distance of the eye; five, six, seven, eight, nine, and ten inches, will in general be most conve. nient, or they may be made only one, two, three, or four inches long, provided distinct vision is obtained at one end, by plac- ing at the other an eye-glass, whose focal length is equai to the length of the reflecting planes. The inclination of the reflec- tor that is in general, most pleasing is 18°, 200, or 22, o, or the 20th. 18th, and 16th part of a circle, but the planes may be set at any required angle, either by a metallic, a paper, or cloth joint, or any other simple contrivance. When the two planes are put together, with their straightest and smoothest edge in contact, they will have the form shewn in fig. 1, where A B C is the aperture or angle formed by the plates. In this figure the plates are rectangular, but it may often be more con- judge or other lawyer could act in the eommission of oyer and terminer, or that of gaol delivery, within the county where he was born or inhabited; but it was thought proper by 12 Geo. II. cap. 27. to allow any man to be a justice of oyer and ter- miner, and general gaol delivery, within any county of England. Justices of the Peace, are persons of interest and credit, appointed by the king’s commission to keep the peace of the county where they live. A justice is to exercise his authority . only within the county where he is appointed by his commis- sion, not in any city which is a county of itself, or town corpo- rate, having their proper justices, &c. but in other towns and liberties he may. The power and office of justices terminates in six months after the demise of the crown, by an express writ of discharge under the great seal, by writ of supersedeas, by a new commission, and by accession of the office of sheriff Or coroner. . Justices of the Peace within Liberties, are justices of the peace who have the same authority in cities or other corporate towns as the others have in counties, and their power is the same, only that these have the assize of ale and beer, wood, and vic- tuals, &c. Justices of cities and corporations are not within the qualification act, 5 Geo. II. cap. 18. - - JUSTIFICATION, in Law, signifies a maintaining or shew- ing a sufficient reason in court, why the defendant did what he is called to answer. Pleas in justification must set forth some special matter: thus, on being sued for a trespass, a person may justify it, by proving that the land is his own freehold; that he entered a fiouse, in order to annrehend a felon; or by virtue of a warrant to levy a forfeiture, or in order to make a distress; and in an assault, that he did it out of necessity. JUSTIFICATION, in Theology, that act of grace which renders a man just in the sight of God, and worthy of eternal happi- ness. See THeologY. Different sects of Christians hold very different opinions concerning the doctrine of justification; some contending for justification by faith alone and others by good works. - K. K. A. L. venient to give them the triangular form shewn at M. fig. 2, or N. fig. 3. - - When the instrument is thus constructed, it may be either covered'up with paper or leather, or placed in a cylindrical, or any other tube, so that the aperture ABC may be left com- pletely open, and also a small aperture at the angular point D. If the eye is now placed at D, and looks through the aperture A B C, it will perceive a brilliant circle of light, divided into - Fig. 1. as many sectors as the number of times, that the angle of the reflectors is contained in 360°. If this angle is 18°, the num- ber of sectors will be 20°; and, whatever be the form of the aperture ABC, the luminous space seen through the instru- ment will be a figure pro- - duced by the arrange- Fig. 3. ment of twenty of these apertures round C, as a: centre, in consequence. - T of the successive reflec- tions between the polished surfaces. Hence it follows, that if 4}- any object, however ugly or irregular in itself, is placed before. the aperture A B C, the part of it that can be seen through the aperture will be seen also in every sector, and every image of the object will coalesce into a form mathematically symmetri- cal, and highly pleasing to the eye. If the object be put in motion, the combination of images will likewise be put in 536 K A. L. K A. L. 'DictionARY or MECHANICAL science. motion, and new forms, perfectly different, but equally sym- metrical, will successively present themselves, , sometimes vanishing in the centre, sometimes emerging from it, and sometimes playing around in double and opposite oscilla- tions. When the object is tinged with different colours, the most beautiful tints are developed in succession, and the whole figure, delights the eye by the perfection of its forms and the brilliancy of its colouring. . . . . - . The motion of the object may he effected either by the hand or by a simple piece of mechanism, or the same effect may be produced by the motion of the instrument over the object, or round, its own axis. In the form of the kaleidoscope now described, the object should be held close to the aperture A B C, and the eye should be placed as nearly as possible in the line CD; for the figure loses its symmetry in proportion as the object recedes from A B C, and as the eye rises above D. The instrument is therefore limited in its present form to the use of objects which can be held close to the aperture. ... In order to remove the limitation, the tube which contains the reflectors should slide in another tube, of nearly the same length, and having a convex lens at its farther extremity, the focal length of the lens should be always less than its greatest distance from the aperture A B C. In general it should be about one-third or one-fourth of that distance, but it will be advisable to have two or even three lenses of different focal lengths, to fit into the end of the outer tube, and to be used as Circumstances may require, or a variation of focal long til may be produced by the separation or approach of two lenses. When the instrument is thus fitted up, it may be applied to objects at all distances; and these objects, whose images are formed in an inverted position at the aperture A B C, may be introduced into the symmetrical picture in the very same man- ner as if they were brought close to the instrument. Hence we can introduce trees, flowers, statues, and living animals; and any object which is too large to be comprehended by the aperture A B C may be removed to such a distance that its image is sufficiently reduced. The kaleidoscope is also constructed with three or more reflecting planes, which may be arranged in various ways. The tints placed before the aperture may be the complementary colours produced by transmitting polarised light through regu- larly crystallized bodies, or pieces of glass that have received the polarising structure. The partial polarisation of the light, by the successive reflections, occasions a partial analysis of the transmitted light; but, in order to develop the tints with brilliancy, the analysis of the light must precede its admission into the aperture. Instead of looking through the extremity D of the tube, the effects which have been deseribed may be exhibited to many persons at once, upon the principle of the solar microscope or magic lantern; and in this way, or by the application of the camera lucida, the figures may be accurately delineated. It would be an endless task to point out the various pur- poses in the ornamental arts to which the kaleidoscope is appli- gable...It may be sufficient to state, that it will be of great use to architects, ornamental painters, plasterers, jewellers, carvers and gilders, cabinet-makers, wire-workers, bookbinders, calico. printers, carpet manufacturers, manufacturers of pottery, and every other profession in which ornamental patterns are required. The painter may introduce the very colours which he is to use; the jeweller, the jewels which he is to ar. range. and in general the artist may apply to the instru- ment the materials which he is to embody, and thus form the most correct opinion of their effect when combined into an 9rºamental pattern. When the instrument is thus applied, an infinity of patterns is created, and the artist can select such aS he considers most suitable to his work. when a knowledge of the nature and powers of the instrument has been acquired by a little practice, he will be able to give any character to the pat- term that he chooses, and he may even create a series of different patterns, all rising out of one another, and returning by similar gradations to the first pattern of the series. In all these cases the pattern is perfectly symmetrical round a centre, or all the imºges of the aperture A B C are exactly alike, but this sym. metry may be altered, for after the pattern is drawn it may be reduced into a square, a triangular, an elliptical, or any other form that he pleases. The instrument will give annular pat- terns, by keeping the reflectors separate, as at AB, fig. 4, and it will give rectilineal ones, by placing the reflectors parallel to each other, as in fig. 5. – . . . º Fig. 4. Fig. 5. The kaleidoscope is also an • instrument of amusement, to bination of musical sounds. When Custillon proposed the construction of an ocular harpsichord, he was mistaken in supposing that any combination of harmonic colours could afford pleasure to the person who viewed them; for it is only when these colours are connected with regular and beautiful forms, that the eye is gratified by the combination. . The kalei- doscope, therefore, seems to realize the idea of an ocular harpsichord. - - tº . . . Since the above was invented, another instrument of this class has been invented by Harris and Co. Holborn, London. This instrument generally consists of two tubes, A B and B C, one of which, B C, is moveable within the other, C being the end next the eye, and A the end next the object. The object cell D is made to screw in the collar A, as is also the lens E. In using the instrument, place the object cell D in the collar A as far as it can go, push in the tube B C completely, holding the instrument so that the sharp point of the triangular aperture - A. B/7 please the eye, by the creation ‘. . . . --- and exhibition of beautiful Al in forms, in the same manner as - the ear is delighted by the com- at C is downwards. The instrument being now kept steady in the hand, turn round the collar A, and by placing the eye at C, will be seen a succession of the most beautiful forms and pat- terns. Hitherto it has been necessary to hold the object as close as possible to the end A of the tube, and to push in the tube B C as far as it would go, but the instrument is adapted to create forms and patterns by means of animate as well as inanimate objects, placed at all distances from the observer. This great advantage is obtained by the lens E and the sliding tube B C. The cell D is now removed, and the lens E being screwed into its place, any object whatever may be introduced into the patterns, merely by directing the instrument towards it, and pulling out or pushing in the , tube B till the pattern is perfect. When the object is about four inches from the lens, the tube requires to be pulled out as far as possible, and for greater distances it must be pushed in. In looking at opaque objects, as a seal, watch-chain, the second hands of a watch, coins, pictures, gems, shells, flowers, leaves, and petals of plants, impressions from seals, &c. &c. the object, instead of being held between the eye and the light, must be viewed in the same manner as we view objects through a microscope, being placed as near the instrument as possible, so as to allow the light to fall freely upon the object. d In most of the instruments there is, near the middle of the tube B C, a mark which is nearly suited to all distances beyond three feet. The object cell D, held in the hand at a distance greater than five or six inches, may be also used when the lens E is in the tube. The furniture of a room, books, and papers laying on a table, pictures on a wall, a blazing fire, the moving foliage of trees, &c. bunches of flowers, horses and cattle in a park, carriages, in motion, the currents of a river, moving in- sects, and in short, every object in nature may be introduced by the aid of the lens, into the figures created by the instru- ment. As dust will (though the greatest care may be observed) collect upon the reflectors, it is advised, that the feather of a quill (well scalded, to take out the grease) be introduced at the end of the sliding draw B C, and drawn up and down until they gº K. E. E. K E L 537 DICTIONARY OF MECHANICAL SCIENCE. are clean, holding the apex of the angular aperture upward, and the instrument a little inclined, the end A downward. KALI, a genus of marine plants, which are burnt to procure alkali. See ALKALI and Kelp. KAMSIN, a hot southerly wind common in Egypt. It pre- vails more or less for fifty days. KANGAR00, in Natural History, a singular animal found in New Holland, It is about the size of a sheep, covered with a short fur of a dark mouse colour. The head, neck, and shoulders, are very small, when compared with the other parts of the body. The tail is long, thick near the rump, and taper- ing towards the extremity. This animal has a false belly, in which its young are carried, and secured from danger. The fore legs are only about eight inches long, while the hind legs are twenty-two. Its progress is by jumps of great lengths, in an erect position. The head and cars have some affinity to those of a hare. KEBLA, an appellation given by the Mahometans to that part of the world where the temple of Mecca is situated, towards which they are obliged to turn themselves when they ray. p KECKLING, or KAICKLING, the art of winding or worming old rope, &c. about a cable, to preserve its surface from being fretted when it rubs against a ship's bow or fore foot, but more particularly it implies the winding of iron chains round the º: to defend it from the friction of a rocky bottom, or from the ice. KEDGE, or KEDGER, a small anchor used to keep a ship steady and clear from her bower-anchor while she rides in a harbour or river, particularly at the turn of the tide, when she might otherwise drive over her principal anchor, and entangle the stock or flukes with her slack cable, so as to loosen it from the ground. The kedge anchors are also used to transport a ship, or remove her from one part of a harbour to another, being carried out from her in the long boat, and let go by means of ropes fastened to these anchors. They are also gene- rally furnished with an iron stock, which is easily displaced for the conveniency of stowing. See ANCH or, WARP, &c. KEEL, the principal piece of timber in a ship, which is usually first laid on the blocks in building. By comparing the carcase of a ship to the skeleton of a human body, the keel appears as the back bone, and the timbers as the ribs. Ac- cordingly the keel supports and unites the whole fabric, since the stem and stern posts, which are elevated on its ends, are, in some measure, a continuation of the keel, and serve to con- nect and enclose the extremities of the sides by transoms, as the keel forms and unites the bottom by timbers. The keel is generally composed of several thick pieces placed lengthways, which, after being scarfed together, are bolted and clinched upon the upper side. False KEEL, a strong thick piece of timber bolted to the bot- tom of the keel, which is very useful in preserving its lower side. The false keel is provided when the thick pieces which form the real keel cannot be procured large enough to give a sufficient depth thereto. In large ships of war the false keel is composed of two pieces, called the upper and lower false keels. The lowest plank in a ship's bottom, called the garboard streak, has its inner edge let into a groove or channel, cut longitudinally on the side of the keel; the depth of this channel is therefore regulated by the thickness of the garboard streak. KEEL, is also a name given to a low flat-bottomed vessel used in the river Tyne, to bring the coals down from Newcastle for loading the eolliers; hence, a collier is said to carry so many keels of coals. KEEL HAULING, a punishment inflicted for various offences in the Dutch navy. It is performed by suspending the culprit by a rope from one yard-arm, with a weight of lead or iron upon his legs, and having another rope fastened to him, leading un- der the ship's bottom, and through a block at its opposite yard- arm ; he is then suddenly let fall from the one yard-arm into the sea, where, passing under the ship's bottom, he is hoisted up on the opposite side of the vessel to the other.—This punishment is not altogether unknown in British ships, but, as it is dangerous, it is very rarely, or indeed scarcely ever, now practised. KEELSON, or KELson, a piece of timber forming the inte- 56. rior or counterpart of the keel, being laid upon the middle of the floor timbers immediately over the keel, and serving to bind and unite the former to the latter, by means of long bolts driven from without, and clinched on the upper side of the keelson. The keelson, like the keel, is composed of several pieces Scarfed together; and in order to fit with more security upon the floor timbers and crotchets, it is notched about an inch and a half deep, opposite to each of those pieces, thereby scored down upon them to that depth, where it is secured by spikenails. The pieces of which it is formed are only half the breadth and thickness of those of the keel. KEEP, in ancient military history, a kind of strong tower, which was built in the centre of a castle or fort, to which the besieged retreated, and made their last efforts of defence. It is also called the donjon, or dungeon. See CAstle. To KEEP, a term used on several occasions in Navigation, as—To Keep the Land Aboard, is to keep within sight of land as much as possible. To Keep the Luff, or the Wind, to con- tinue close to the wind; i.e. sailing with a course inclined to the direction of the wind as much as possible. To Keep Off, to sail at a distance from the shore or a ship, &c. See the article OFFING. KEEPER of The GREAT SEAL, is a lord by virtue of his office, and styled the Lord Keeper of the Great Seal of England. He is one of the King's Privy Council, &c. through whose hands pass all charters, commissions, and grants of the king under the great seal ; without which, such instruments are of no force. Keeper of the Privy Seal, is a lord by virtue of his office, through whose hands pass all charters signed by the king be- fore they come to the great seal. I}oat Keep ER, one of the boat's crew who remains as a sentinel, in his turn, to take care of the boat and her contents when she is ashore, or alongside of a ship, or is towed astern of her. KEEPING, in Painting, denotes the representation of ob- jects in the same manner that they appear to the eye at different distances from it, for which the painter should have recourse to the rules of Perspective. There are two instances in which the famous Raphael Urbin has transgressed these rules: in one of his cartoons, representing the miraculous draught of fishes, the men in each of the two boats appear of full size, the features of their face being strongly marked ; and the boats are represented so small, and the men so big, that any one of them appears sufficient to sink either of the boats by his own bare weight; and the fowls on the shore are also drawn so big, as to seem very near the eye of the observer, who could not possibly, in that case, distinguish the features of the men in the distant boats. Or, supposing the observer to be in either of the boats, he could not see the eyes or beaks of the fowls on the shore.—The other instance occurs in his historical picture of our Saviour's transfiguration on the mount; where he is re- presented with those who were then with him, almost as large as the rest of his disciples at the foot of the mount, with the father and mother of the boy whom they brought to be cured; and the mother, though on her knees, is more than half as tall as the mount is high. So that the mount appears only of the size of a little hay-rick, with a few people on its top, and a greater number at its bottom on the ground ; in which case, a spectator at a little distance could as well distinguish the fea- tures of those at the top as those on the ground. But upon any large eminence, deserving the name of a mount, that would be quite impossible. KEILL, Dr. John, an eminent mathematician and philoso- pher, was born at Edinburgh in 1671 ; and studied in the uni- versity of that city. Keill was author of several works, but was more distinguished in his time for the conspicuous part he took in the dispute between Leibnitz and Newton concerning the invention of fluxions. KELP, a term which is used in Britain to signify the saline substance obtained by burning seaweed, which is chiefly em: ployed in the manufacture of green glass. Different species of seaweed, belonging to the genus Facus, and order Algae, are cultivated for this purpose. These plants are thrown on the rocks and shores in great abundance, and in the summer are raked together, and dried as hay in the sun and wind, and 6 X. 538 K E T K. I E DICTION ARY OF MECHANICAL SCIENCE, afterward burnt to the ashes called help. The process of making it is thus:—The rocks, which are dry at low water, are the beds of a great quantity of seaweed, which is cut, carried to the beach, and dried; a hollow is dug in the ground three or four feet wide; round its margin are laid a row of stones, on which the seaweed is placed, and set on fire within, and quan- tities of this fuel being continually heaped upon the circle, there is in the centre a perpetual flame, from which a liquid, like melted metal, drops into the hollow beneath; when it is full, as it commonly is ere the close of the day, all heterogeneous matter being removed, the kelp is wrought with iron rakes, and brought to a uniform consistence in a state of fusion. When cool, it consolidates into a heavy dark-coloured alkaline sub- stance, which undergoes in the glass-houses a second vitrifica- tion, and, when pure, assumes a perfect transparency. See CHEMisTRY and SODA. KENTLEDGE, pigs of iron for ballast, laid upon the floor, near the keelson, fore and aft. Limber Kent Ledge, pigs of iron or lead, cast to fit between the floor timbers, or in the limbers. KEPLER, John, a very eminent astronomer and mathema- tician, was born in the duchy of Wirtemberg in 1571. To him we owe the discovery of the true figure of the orbits, and the propor- tion of the motions of the solar system. This astronomer had a particular passion for finding analogies and harmonies in nature, after the manner of the Pythagoreans and Platonists. The great sagacity of this astronomer in the planetary motions, suggested to him some views of the true principles from which these motions flow. He speaks of gravity as of a power that was mutual between bodies; and says, that the earth and moon tend towards each other, and would meet in a point so many times nearer to the earth than to the moon, as the earth is greater than the moon, if their motions did not hinder it. He H adds also, that the tide arises from the gravity of the waters towards the moon. But not having notions sufficiently just of the laws of motion, he was unable to make the best use of these ideas. - KEPLER’s Laws, a term used by astronomers to denote cer- tain analogies between the distances of the planetary bodies and their times of periodic revolution, as also between the rate of motion of any revolving body, whether primary or secondary, and its distance from the central body about which it revolves; to which may also be added, the figure of the planetary orbits, and the position of the central body; these, in the order in which they were discovered, stand as follows:–1. Equal areas are described in equal times: that is, if a line be supposed to join the central and revolving body, this line passes over or de- sqribes equal areas in equal times, whether the planet be in its aphelion, perihelion, or any other part of its orbit. 2. The planets all revolve in elliptic orbits, situated in planes passing through the centre of the sun ; the latter body occupying one of the foci of the ellipse. 3. The squares of the times of revo- lution of the several planetary bodies, are as the cubes of their respective distances from the sun. KEPLeR’s Problem, is the determining the true from the mean anomaly of a planet, or the determining its place in the ellip- tic orbit answering to any given time; and so named from the celebrated astronomer Kepler, who first proposed it. The ge- neral state of the problem is this: to find the position of a right line, which, passing through one of the foci of an ellipse shall cut off an area, which shall be in any given proportion to the whole area of the ellipse; which results from this property, that such line sweeps areas that are proportional to the times. KERMES, in Zöology, the name of an insect produced in the excrescences of a species of the oak. See Coccus. KERMES, Mineral, so called from its colour, which resembles that of a vegetable: kermes is one of the antimonial prepara- tions. See CHEMISTRY and MATERIA MEDICA. KERSEY, John, an able English mathematician, who flou- rished towards the close of the seventeenth and beginning of the eighteenth century, and is chiefly known in the scientific world by his “Elements of Algebra,” in two vols. folio, which is an ample and complete work, containing a full explanation of the problems of Diophantus; he was author likewise of “Dictiona. rum Anglo-Britanicum,” or General English Dictionary. KETCH, a vessel equipped with two masts, viz. the main- mast and the mizzen-mast, and usually from 100 to 250 tons burden. Ketches are principally used as yachts for conveying princes of the blood, ambassadors, or other great personages, from one place to another. Ketches are likewise used as bomb-vessels, and are therefore furnished with all the appa- ratus necessary for a vigorous bombardment.—Bomb-ketches, are built remarkably strong, as being fitted with a greater number of riders than any other vessel of war; and indeed this reinforcement is absolutely necessary to sustain the vio- lent shock produced by the discharge of their mortars, which would otherwise in a very short time shatter them all to pieces. KEWELS, or SH evils, a frame composed of two pieces of timber, whose lower ends rest in a sort of step or foot, nailed to the ship's side, from whence the upper ends branch out- ward into the arms or horns, serving to belay the sheets or great ropes by which the bottoms of the main-sail and fore-sail are extended. Kevel-HEADs, the ends of the top timbers, which rising above the gunnel serve to belay the ropes, or take a round turn to hold on. KEY, or Key Note, in Music, a certain fundamental note or tone, to which the whole of a movement has a certain rela- tion or bearing, to which all its modulations are referred and accommodated, and in which it both begins and ends. There are but two species of keys: one of the major, and one of the minor mode; all the keys in which we employ sharps or flats being deduced from the natural keys of C major and A minor; of which they are mere transpositions. KEYS of AN ORGAN, moveable projecting levers in the front of an organ, so placed as to conveniently receive the fingers of the performer, and which, by a connected movement with the valves or pallets, admit or exclude the wind from the pipes. See ORGAN. KEY Stone of an arch or vault, that placed at the top or ver- tex of an arch, to bind the two sweeps together. This, in the Tuscan and Doric orders, is only a plane stone, projecting a little ; in the Ionic, it is cut and waved somewhat like consoles; and in the Corinthian and Composite orders, it is a console, enriched with sculpture. KEY, an instrument for the opening of locks. See Lock. The invention of keys is owing to one Theodore of Samos, according to Pliny and Polydore Virgil: but this must be a mistake, the use of keys having been known before the siege of Troy; mention even seems made of them in the 19th chapter of Genesis. Molinus is of opinion, that keys at first only served for the untying certain knots wherewith mankind anciently secured their doors: but there were keys, he main- tains, in use nearly akin to our own; they consisted of three single teeth, and made the figure of an E.; of which form there are still some to be seen in the cabinets of the curious. KEY, or Quay, a long wharf by the side of a harbour or river, usually built of stone, and having several store-houses for the convenience of lading and discharging merchant ships. It is furnished with posts and rings, whereby ships may be secured, as also with cranes, capstans, &c. to load or unload the vessels which lie alongside. Keys, are also certain sunken rocks, lying near the surface of the water, particularly in the West Indies. KIDNAPPING, is the forcibly taking and carrying away a man, woman, or child, from their own country, and sending them to another. This is an offence at common law, and pun- ishable by fine, imprisonment, and pillory. By statute 11 and 12 William III. c. 7, if any captain of a merchant vessel shall during his being abroad, force any person on shore, and wilful- ly leave him behind, or refuse to bring home all such men as he carried out, if able and desirous to return, he shall suffer three months' imprisonment. Exclusive of the above punishment for this as a criminal offence, the party may recover upon an action for compensation in damages for the civil injury. KIEFEKIL, a mineral dug up near Konie, in Natolia, and is employed in forming the bowls of Turkish tobacco-pipes. It is found in a large fissure six feet wide, in gray calcareous earth. When fresh dug it is of the consistence of wax ; it feels soft and greasy ; its colour is yellow; its specific gravity 1-600; when thrown on the fire, it sweats, emits a fetid vapour, becomes hard, and perfectly white. According to the analysis of Klap- - - | - - º - | - - - º - - - - - - º - N. - - - - N. º - -- - º - - º - º - º - º - - S. - N - - º - & - - º -- º - - | - - s K I L K I L 639 DICTIONARY OF MECHANICAL SCIENCE, roth, it is composed of 50:50 silica; 17.25 magnesia; 25.00 water; .500 carbonic acid; and 50 lime. KILDERKIN, a liquor measure containing 18 gallons beer measure, and 16 gallons ale measure. KILN.—Description of a Vertical Kiln for Drying Corn. By Mr. James Jones, of Holborn, London.—No subjects which can be brought under the consideration of society, combine more real interest and importance than those which involve the production and preservation of the chief necessaries of human life; in this view, the great value of a speedy and effectual method of dry- ing grain is evident. The frequent occurrence of crops being, on account of unfavourable weather, necessarily carried from the field in a state of considerable humidity, every one must be aware of; and the consequent reduction in the value of the produce, arising from the deterioration in its quality, cannot be. less evident. The heat generated by the fermentation in the heap, together with the moisture, causes germination to take place in the grains near the surface, whereby the farina is de- composed, and the nutritive properties are in a great measure destroyed, whilst the lower part becomes mouldy, and acquires a musty smell, of the most foul and disgusting kind; but grain laid up in a perfectly dry state suffers no change, and history furnishes numerous instances of the discovery of ancient gra- naries, wherein the corn has been preserved, in the most perfect condition, for a long series of years; which, had it been stored in a state of dampness, would have inevitably been destroyed. This, in the time of wet harvests, renders essentially necessary some artificial means of speedily dissipating the moisture, which is so destructive if allowed to continue in the grain; and the only means of effecting this object has hitherto been by the use of the common kilns, but which, in very bad seasons, on account of the slowness of their operation, are not sufficiently, numer- ous to answer the purpose to the extent required. As an appendage to large granaries, or corn stores, kilns are of in- finite utility, both as affording the certain means of preserving the grain from any tendency to fermentation whilst lying in store, and fitting it for water-carriage by that degree of dryness which is absolutely necessary to prevent its heating on board, where the opportunities of turning it are so limited, if not alto- gether wanting, although the necessity of it is increased ; and to the miller the use of a kiln is not less important, as, without a certain degree of dryness, the wheat will not grind freely, it clogs the stones, and good flour is not produced; and it is a very general practice with millers, who possess the means, to pass all wheat over the kiln when the flour is intended for water carriage; at least, it is the custom at some mills ; and it is well known, that new flour of the finest quality, when damp, has a remarkable predisposition to encourage the propagation of those minute insects which are destructive of its good proper- ties. From these prefatory remarks on mischief and loss arising from wheat and grain being housed when damp, we proceed to our description of the malt kiln. The common kiln is so well known, that little need be said in the way of description, except to enable those who are unac- quainted with its construction, to judge of the comparative merits of the old kiln and those hereafter described ; suffice it to say, that it consists of a floor, usually composed of Bridgewater tiles, which are large square flat tiles, perforated with a great number of small holes; or otherways of iron plates perforated in the same way; or of wove wire work, either kind being sup- ported on iron bearing-bars extending from wall to wall. Be- neath this floor or kiln head, as it is frequently called, are built four portions of arches of brickwork, which together compose a form somewhat similar to an inverted frustum of a pyramid, whose larger base is equal to the area of the floor; and in the lesser base, which is supported on low walls, is placed, at the distance of five or six feet from the tiles, a fire composed of coke, culm, or other suitable fuel : the heated air and vapour from which ascends into the pyramidal space above it, spread- ing rather unequally over the inferior surface of the floor, pass- ing through the perforations made in it, and through the inter- stices between the grain, which is spread in considerable thick- ness upon it; the lower part of the stratum thus necessarily gets considerably heated, and the humidity is evaporated. Af- ter a lapse of time, dependent on the state of the grain, it is turned over with a large wooden shovel, or scoop, for the pur- pose of removing those grains which were before at the top, nearer to the heated surface,and those which are sufficiently dried, to the top ; and is then suffered to remain until it is fit to be turned again, if from its previous damp state that is necessary, or to be removed entirely from the kiln, when a fresh quantity is submited to the same operation. The length of time it lies on the kiln depends on the proportion of moisture contained in the grain, and varies from five to eight or nine hours; indeed, Tull states the occasional necessity of extending it as far as twelve hours. On the kilns in use, previously to recent improvements, the average time required for the purpose was seven hours and a half, during which time four quarters and a half were dried, being at the rate of fourteen quarters and a half per day. - It must be evident that a stratum of wheat several inches thick, cannot be equally heated through all its parts in a short time, and, consequently, that the moisture which is expelled. from the grains nearest the tiles, by the first effect of the fire, in the form of steam, must, in its ascent, be condensed and de- posited on the colder grains which are nearer to or at the sur- face; and, consequently, so far as regards the upper part of the stratum, the evil is doubled, and until the grain is turned over, (unless that operation is excessively delayed,) the upper por- tion does not part with any of its previous or acquired mois- ture, and when it is turned, it must be allowed to remain long enough to evaporate, perhaps twice its original quantity of hu- midity, during which time the part which was first dried re- absorbs much of the moisture exhaled from the other grains, by which the time requisite to expel the whole is greatly extended. Whether any, or what chemical action takes place, detrimen- tal to the flour in this protracted state of humid heat, we are not prepared to state ; but it will not be doubted that the least possible time in which the purpose can be effected, the less chance there is of injurous change; and it will be admitted, that in those kilns heated by the direct action of the fire, the longer the grain remains, the more it will imbibe of the un- pleasant effluvium arising from the fuel ; but in kilns where the drying is performed by heated air alone, this objection does not exist. The operation of turning must obviously be an imper- fect and inefficient one, notwithstanding every attention may be paid by the man performing it, for it is impossible he can turn the whole completely; but, from the circumstance of its being an unpleasant operation, it is seldom performed as effee- tually as it perhaps might be ; but let the care and attention employed be unlimited, still, from the inequalities of the sur- face on which the grain lies, it is utterly impossible that the . turning can be so complete, but that some of the grains remain undisturbed, and much is necessarily again brought into con- tact with the tiles, and therefore becomes over dried, to the injury of the entire quantity; and in fact the experience of every day shews the inequality of this mode of drying, as fre- quently, if not always, some of the grains are quite parched, whereby the quality of the flour is much injured, while others are thrown off the kiln almost as damp as when laid on. That the imperfections here stated attach to the use of the common kiln, every person acquainted with the subject will acknowledge, and to such persons the communication of an effectual remedy will not be unacceptable. In the latter part of the year 1821, Mr. Jones was applied to by John Snook, the proprietor of large mills at Bedhampton, Hants, to endeavour to effect some improvement in his kilns, so as, if possible, to obviate the existing objections ; , and although at that time he was perfectly unacquainted with the subject, very little reflection sufficed to convince him that the principles of the old method were bad ; instead of attempting any alterations in the old kilns, after a good deal of consider- ation, he proposed the adoption of one altogether new, both in construction and in the manner of its operation, the exposure of a very thin stratum of grain, an equal temperature, the pas- sage of a large quantity of warm air, and an uninterrupted re- moval or turning; each of which are indispensable where per- fection is sought. This proposition of Mr. Jones was approved, and the first trial sufficiently proved the superiority of the new method over the old one, for the work it did, compared with one of the old kilns, which was at work a few days before, and with the same wheat, was rather more than as six to one. The drawings explanatory of the machine are, fig. 1, (see 540 K I L K I L DITIONARY OF MECHANICAL SCIENCE, plate), an elevation, fig. 2; a vertical section through the line a b. Fig. 3, a horizontal section through the line c d, and fig. 4, a vertical section of the fireplace on the line ef. The same let- ters indicate the same parts in each figure. The body of the kiln is composed of two concentric cylinders A A and B B, closed attop and bottom by two concentric cones C C and D D, the external cylinder, and the bases of its two cones, are six feet two and a half inches diameter, and eight feet high ; the internal cylinder and its two cones are six feet diameter, and seven feet ten inches high; having an annular space, one inch and a quarter wide, between the internal and external bodies, which are perforated into iron plates, having 2300 small holes: in each square foot. The kiln is supported on five cast iron columns E, E, E, E, E, six feet six inches high, which are at- tached at their tops to a strong iron ring which surrounds the base of the cylinder. From the heads of these columns descend | along the sides of the cone five long bolts G, G, G, G, G, which are passed through the same number of lugs in the cast iron ring H, which surrounds the neck of the lower cone; from the same ring H also proceed five stays I, I, I, I, I, which are fas- tened through the middle of the columns by a nut on each side. The columns were made of the height here stated, for the pur- pose of enabling the wheat to be received into sacks, that being the most convenient under the particular circumstances; but in a mill where an elevator is near at hand, or where it would not be inconvenient to allow the wheat to run on the ſloor, the whole kiln might be brought lower down, and as great a length of cylinder as the height of the granary floor.will admit of, may be used, as by the grain having a greater distance to descend, the motion would be more rapid, and, consequently, the turning will be more complete. The body is sustained both internally and externally by iron hoops K, K, K, and the distance between the cylinders is preserved by a number of short stays. When the kiln is in operation, the annular space before spoken of is entirely filled with wheat, by means of the spout W, from the granary, which keeps up a constant supply as fast as its exit is allowed at the discharging spout X, the opening of which is governed by a regulator, being adjusted to the time requisite to evaporate the moisture. - - . . . . " In the front of the kiln is cut out a space L, M, N, O, P, in which is fixed the fireplace L, M, Q, P, in which Q is the fire- hole, and R, R, are openings with doors, for the purpose of cleaning the flues; S is the ash hole, and T the fire bars. On reference to the sections, it will be seen that there are vertical air-passages, round which the flame and heat of the fuel circu- late to the right and left, until they reach the chimney, which rises through nearly the centre of the kiln ; the course of the flame is evident, by the direction of the arrows, and in its pas- | sage to the chimney it very powerfully heats the plates which form the sides of the air-passages, and occasions a constant rush of hot air through them into the body of the kiln. The whole of the fireplace being enclosed within the kiln, it is en- tirely surrounded (excepting in the front) by a thin shell or casing of grain ; and, from its perfect insulated situation, no part of its heat can escape, without having first performed its destined office. The triangular space or opening immediately over the fireplace answers two purposes, the chief of which is, diverting the wheat, as it descends, from coming too near the fire, whereby it would be parched, and it affords a convenient entrance into the kiln when requisite. The front part of the fire- place is supported on the heads of the two front columns, and the hinder part within the kiln by the pillar g, the top of which is fixed in a socket in a bearing-bar across the bottom of the fire place, and the lower end stands in a cup in the intersection of an iron cross, which rests in the ring, H, before mentioned, and the weight of the fireplace (nearly 15 cwt.) is consequent- ly sustained by the bolts G, G, which descend from the heads of all the columns. : * From this description, together with the drawing, the con- struction will be easily understood ; and few words will be re- quisite to explain its operation. The fire having been lighted, the wheat is admitted from the granary, the regulator at bottom being for a few minutes kept shut; when, the annular space be- ing full, the only way the warm air contained in the upper part of the kiln can escape, is through the holes in the iron, and the interstices between the grains ; and as, the stratum or shell of | as 95 : 14.5 :: 6'5: 1. wheat is so thin, the passage of air is very rapid, and conse- quently the moisture is taken up by it, and carried off with the utmost celerity. With regard to the motion or stirring it un- dergoes, a few words may be requisite. The apex of the cone (where the wheat enters) has the greatest heat; here it is in a state of constant diverging motion, rapid where the heat is greatest, and progressively slower as the temperature diminish- es, until it reaches the cylinders, where the motion becomes equable. Here the wheat would perhaps descend bodily, but the roughness left by the punching of the holes in the iron plate, is highly useful, as the little resistance it offers to the grain sliding down produces a constant, slow, rolling intestine motion, whereby every individual grain is exposed to the same degree of temperature; it then again converges in the lower cone, pro- ducing the same turning and mixing motion, as in the upper cone, and ultimately escapes through the spout at the bottom either into sacks or on the ground, as may be desired. Evapo- ration is at first strongly excited, and then gently kept up by a progressively decreasing temperature, as the grain descends towards the discharging spout; during the time the kiln is at work, the operation of screening is to a certain extent constant- ly going on, by which much of the dust, seed, insects, and other extraneous matters, are separated; and it is well known that grain cannot be too well screened from all impurifies previous to storing, as its perfect preservation depends much on tha circumstance. The rapidity of its operation is such, that the grain flows from it perfectly dried, at the rate of 29 loads, or 145 quarters, per day; which can only be accounted for by the circumstance of the aqueous vapour being carried clear away at once, without any part of it being deposited on other grains, and from the great quantity and rapidity of the cur- rent of warm air which constantly passes between the grains, taking up the humidity as fast as it is converted into vapour. It is dried with perfect equality, and above all, the quantity dried is six or seven times as great as by the common method ; for the kiln which was removed to make room for the new one, dried (as before stated) on the average, fourteen quarters and a half per day, the medium quantity being 95 quarters: then Or if we take the quantities before men- tioned, the proportion will be as ten to one. For as 145: 14.5: : 10 : 1. This to the corn-merchant is an advantage of much importance, as frequently, on sudden changes of the markets, it is desirable to ship the grain with the utmost despatch, but | the shipment is often much delayed by the necessity of kiln- drying the cargo previous to loading the vessels; by which delay, arising from the tardiness of the common operation, the advantages of a good market are not unfrequently lost. Improved Malt Kilms for drying Malt by heated Air.—The common malt kiln is a square building, widening gradually within from the fireplace to the floor on which the malt is laid. It may be compared to an inverted pyramid having a fireplace in its vertex, and its base covered by a floor, on which the malt is dried by the heat, and more or less smoke, which ascends from the fire beneath. The floor, as we have described it, con- sists of iron bars covered by tiles, which have large holes made nearly through them from the lower side, and then very small holes pricked quite through. In some kilns, webs of wire covered with hair cloth, are used instead of the perforated tiles. The fuel commonly used is either coke, or Welsh stone coal —sometimes wood—and the hot air that passes through the malt has previously passed through the naked fire; but in the improved kilns, of which we have given engravings, from the Parliamentary Report on the Distilleries in Scotland, the smoke and fumes of the fuel are prevented from coming to the malt ; the air that dries it receiving its heat in passing through a heated cast-iron tube. Fig. 1. (see plate) is a front view of an improved malt kiln, in which a a, is the furnace door, b the fire, through which the air rises, the grate being of the common kind; c a cast-iron tube, which passing through the fire, and having one end open to the external air, and the other open into the kiln, conveys leated air to the grain; d, a flue around the fire, in which air is also heated and conveyed to the grain; e, the ash pit; f, the chimney. Fig. 2. A side view of a malt kiln, in which the grain is dried by heated air, as in fig. 1, but in which the air necessary for - s > º - º | . | | | § | | | | | --- -T - | - - - - | |-- | | § s s s N -- º - -> | -- - - = −. - - º | | - - - - K I N K N. A 541. DICTIONARY OF MECHANICAL | SCIENCE. combustion of the fuel descends through the grate; a, the fire; b, the grate; c, the door of the furnace; d, the door of the ash pit; e, the air tube; f, the ash pit; g, the end of the air tube entering the space below h, the kiln head, which is composed of the tiles perforated with small holes, lying on the joists i, and supporting the malt k; ll, the windows, through which a current of air may freely enter or escape; m, the air outlets above. . If a distiller finds his buildings so relatively situated that he can lead the air cylinder of his malt kiln through the flue of his still or mash boiler furnace, the expense of fuel for drying malt may be saved. ' KINDRED. See INHERITANCE. KING. The executive power in Great Britain and Ireland is vested in a single person. Formerly, the succession being in- terrupted, there was occasionally a distinction between a right- ful king, or king de jure, and a king in possession of the throne, or king de facto; but it seems now only necessary to consider the rightful power and authority of the king, lawfully and peaceably in possession of the throne. And in this country the crown is by common law hereditary in a peculiar manner, but not de jure divino ; and it may be changed into the limita- tion of its descent by the authority of the king, lords, and com- mons in parliament assembled, but it is not elective. It de- scends regularly to lineal descendants by right of primogeniture, but in case of no male heir, it descends to the eldest daughter only, and to her issue, and not in coparcenary to all the daugh- ters. In failure of lineal heirs, it goes to collateral descend- ants, but there is no failure on account of half blood. Lands also purchased by the king descend with the crown. The in- heritance is not indefeisible, but may be altered as above. But, however limited or transferred, it still retains its heredita- ble quality to the wearer of it, and hence the king never dies, but his right vests eo instanti in his heir. If the throne becomes vacant, whether by abdication, as in the time of James II. or by failure of all heirs, the two houses of parliament may dispose of it. It is now limited to the heirs of the princess Sophia, grand-daughter of James I. being protestant, and married to protestants. -- To assist the king in the discharge of his duties and mainte- tenance of his dignity, and exercise of his prerogative, he has several councils, as the Parliament, his Peers, and his Privy Council, which see. For law matters, the judges are his council. The principal duty of the king is to govern his people according to law; and in consideration of the duties incumbent on him, his dignity and prerogative are established by the laws of the land; it being a maxim in the law, that protection and subjec- tion are reciprocal. See PR eroe Ative. KING at ARMs, or of Arms, an officer who directs the he- ralds, presides at their chapters, and has the jurisdiction of armory. There are three kings of arms in England, viz. Garter, Clarencieux, and Norry, and one for Scotland, viz. Lyon. KING’s Bench, is the supreme court of common law in Eng- land: and so called, because the king used to sit there in person; it eonsists of a chief justice, and three puisne justices, who are by their office the sovereign conservators of the peace, and supreme coroners of the land. This court has a peculiar jurisdiction, not only over all capital offences, but also over all other misdemeanors of a public nature, tending either to a breach of the peace, or to oppression or faction, or any manner of misgovernment. It has a discretionary power of inflicting exemplary punishment on offenders, either by fine, imprison- ment, or other infamous punishment, as the nature of the crime, considered in all its circumstances, shall require. The jurisdiction of this court is so transcendent, that it keeps all inferior jurisdictions within the bounds of their autho- rity; and it may either remove their proceedings to be deter- mined here, or prohibit their progress below; it superintends all civil corporations in the kingdom ; commands magistrates and others to do what their duty requires, by mandamus, in every case where there is no specific remedy ; protects the liberty of the subject, by speedy and summary interposition ; and takes cognizance both of criminal and civil causes, the former in what is called the crown side, or crown office, the lat- ter in the plea side of the court. This court has cognizance, on the plea side, of all actions of trespass, or other injury alleged to be commited vi et armis ; of actions for forgery of 56. * - deeds, maintenance, conspiracy, deceit ; and actions on the case, which allege any falsity or fraud. In proceedings in this court the defendant is arrested for a supposed trespass, which in reality he has never committed, and being thus in the custo- dy of the marshal of this court, the plaintiff is at liberty to proceed against him for any other personal injury, which sur- mise of being in the custody of the marshal the defendant is not at liberty to dispute. This court is likewise a court. of appeal, into which may be removed, by writ of error, all determinations of the court of Common Pleas, and of all inferior courts of re- cord in England. . KING's Palace. The limits of the king’s palace at Westmin- ster extend from Charing-cross to Westminster-hall, and have such privileges as the ancient palaces. * . KINK, a sort of twist or turn in any cable or rope, occa- sioned by its being very stiff, or close laid, or by being drawn too hastily out of the roll or tier in which it was coiled. See the article CoILING: * KIRCHER, ATHANASIUs, a celebrated mathematician, was born at Fulde in 1601. He wrote an immense number of books, amounting altogether to twenty-two volumes folio, ele- ven quarto, and three octavo. It must, however, be allowed, that their utility bears no proportion to their magnitude, and it would therefore be useless to give a catalogue of them in this work, as there is no one of them but has been superseded by later authors. Kircher died in 1680, in his 80th year. KITE, CAPTAIN DANsey's, for effecting a communication between a stranded ship and the shore, or under other cir- cumstances, where badness of weather renders the ordinary means impracticable. A sail of light canvass or holland, is cut to the shape, and adapted for the application of the principles of the common flying kite, after the manner in which Dr. Franklin used to swim on his back in water; and is launched from the vessel or other point to windward of the space over which a communication is required, and as soon as it appears to be at a sufficient distance, a very simple and efficacious mechanical apparatus is used, to destroy its poise, and cause its immediate descent; the kite remaining, however, still attached to the line, and moored by a small anchor with which it is equipped. The kite during its flight is attached to the line by two cords placed in the usual manner, which preserve its poise in the air; and to cause its descent, a messenger is em- ployed, made of wood, with a small sail rigged to it. The line being passed through the cylindrical hole of this messenger, the wind takes it rapidly up to the kite, where, striking against a part of the apparatus, it releases the upper cord, and by that means the head of the kite becomes reversed, and it descends with rapidity. In the experiments made by Captain Dansey, with a view of gaining a communication with a lee- shore, under the supposition of no assistance being there at hand, a grapnel, consisting of four spear-shaped iron spikes, was fixed to the head of the kite, so as to moor it in its fall ; and in this emergency, the attempt of some person to get on shore along the line, would be the means resorted to. In those cases where a communication has been gained, and the main- tenance of a correspondence has been the object, the person to windward has attached a weight to the messenger, in some cases as much as three pounds, which, having been carried up, has of course descended with the kite ; the person to leeward has then furled the sail of the messenger, and loaded it with as much weight as the kite could lift, then replacing the appa- ratus, and exposing the surface of the kite to the direct action of the wind, it has rapidly risen, the messenger running down the line to windward during its ascent. The kite with which the Captain performed the greater part of his experiments, extended 1100 yards of line # of an inch in circumference, and would have extended more, had it been at hand. It also extended 360 yards of line 13 inch in circumference, and weighing 60 lbs. The holland weighed 34 lbs. ; the spars, one of which was armed at the head with iron spikes, for the purpose of mooring it, 64 lbs., and the tail was five times its length, composed of 8 lbs. of rope and 14 lbs. of elm plank. Captain Dansey has deposited a complete apparatus with the Society of Arts, who have very properly presented him with their gold Vulcan medal, for his valuable invention and communication. KNAPSACK, a rough leather or canvass bag, which is strap- 6 Y * 542 K. N. E. K. N. E. DICTIONARY OF MECHANICAL SCIENCE, ped to an infantry soldier's back when he marches, and which contains his necessaries. Square knapsacks are supposed to be most convenient. They should be made with a division to hold the shoes; blacking-balls, and brushes, separate from the linen. KNEADING MILL, is a contrivance by which large quanti- ties of flour are mixed and incorporated into dough, in place of kneading it with the baker's feet, or by a large spatula. The kneading mill does this business very completely, with a great saving of time and labour. It is used at the public baking- houses of Genoa. . . - - A, in fig. 4, is a frame of wood which supports the axis of the machine; a wall 14 palms high from the ground may be made use of instead of this frame. B, a wall three palms and a half thick, through which the aforesaid axis passes. C, another wall similar to the former, and facing it, at the distance of 21 palms. D, the axis, thirty palmas in length, and one palm and one-third in thickness. E, the great wheel, fixed to the said axis, between the frame and the wall; its diameter is 28 palms, and its breadth, which is capable of holding two men occasionally, is five palms. F, are steps, by treading on which the men turn the wheel very smartly; they are two palms dis- tant from each other, and one third of a palm in height. G, a small wheel with cogs fixed almost at the further extremity of the axis; its diameter is 12# palms. H, a beam of wood which extends from one wall to the other; being 21 palms in length, and one and a third in thickness. A similar beam, not seen in the figure, is on the opposite side of the axis. I, a transverse piece of wood, placed near the wall C; it is fixed into the two beams, and serves to support the further extremity of the axis: its length is 14 palms, and its thickness one and a third : there is likewise a transverse piece, which cannot be seen in the figure, 14 palms long, and half a palm thick, placed close to the wall B. K is a strong curved piece of oak, fixed transversely in the side beams H, to receive the axis of the trundle; its Fig. 1. I5 * --- length is 14, palms, and its thickness 14. L is a trundle of 54 palms in diameter, and 14 in height, which is moved by the cogged-wheel G. M is an axis proceeding from the trundle L, and continued through the cross N to the bottom of the tub P; the centre is made of iron, partly square and partly round, and it turns in a socket of brass. The first part of this axis between the trundle L, and the cross N, is of square iron, surrounded by two pieces of wood, held together by iron hoops, which may be removed at pleasure, to examine the iron within; its length is three palms, its diameter about one palm. The second part of the axis, which is within the tube, is made like the first part; its height is 13 palm, its diameter 14. The wooden sheath of this part of the axis is fixed to the bottom of the tub, by means of three screws with their nuts. The axis is distant one-third of a palm from the nearest triangular beater of the cross. N, the gross formed of two bars of wood unequally divided, so that the four arms of the cross are of different lengths: one of the two pieces of wood of which the cross is made, is six palms in length, the other five: their thickness is iſ of a palm, and their breadth one paltn. O; four pieces of wood, called beaters, of a triangular shape, fixed vertically into the extremities of, and underneath, the arms of the fore-mentioned cross: they are 14 palms in length, and half a palm in thickness; and beat or knead the dough in the tub at an equal distance from the cen- tre. P is a stout wooden’tub about a quarter of a palm thick, well hooped with iron; its diameter is six palms, its height 1% in the clear. * > - . . . Fig. 2. v_ſ. Tº En Fig. 2, is a box or trough of wood, four palms long, and three wide, in which the leaven is formed (in about an hour) in a stove, and in. which it is afterwards car- - ried to the tub P. Fig. 3, exhibits a view of the trundle, cross, &c. with a section of the tub. Fig. 4, is a bird's eye view of the cross and tub, with the upper ends of the triangular beaters. r - This tub, P, will contain 18 rubbi (about 19 bushels) of flour, which is carried to it in barrels; the leaven is then carried to it in the box or trough, fig. 2, and when the whole is tempered with a proper quantity of warm water, the men work in the wheel till the dough is properly and completely kneaded. In general a quarter of an hour is sufficient to make very good dough ; but an experienced baker, who superintends, deter- mines that the operation shall be continued a few minutes more or less, according to circumstances. The measures in the preceding description are given in Genoese palms, each of which is very nearly equal to 9.85 of our inches. The machine- ry may be varied in its construction according to circumstances, and the energy of the first mover much better applied than by men walking in a common wheel. - º Fig. 3. * --> lituus. TTTTTTTTTTTTT'ſ ºttii T & A. Nüß E-> --> |millſ. º | | Illi KNECK, the twisting of a rope or cable as it is veering out. KNEE, a crooked piece of timber having two branches or arms, and generally used to connect the beams of a ship with her sides or timbers. The branches of the knees form an angle of greater or smaller extent, according to the mutual situation of the pieces which they are designed to unite. One branch is securely bolted to one of the deck-beams, and the other in the same manner strongly attached to a corresponding timber in the ship's side. Besides the great utility of knees in connecting the beams and timbers into one compact frame, they contribute greatly to the strength and solidity of the ship, in the different parts of her frame to which they are bolted, and thereby enable her, with great firmness, to resist the effects of a turbulent sea. In fixing of these pieces, it is occasionally necessary to give an oblique direction to the vertical or side branch, in order to avoid the range of an adjacent gun-port, or because the knee may be so shaped as to require this dispo- sition, it being sometimes difficult to procure so great a variety of knees as may be necessary in the construction of a number of ships of war. In France, the scarcity of these pieces has frequently obliged their shipwrights to form their knees of iron. º: KNees, are those which are fixed rather obliquely, to avoid, as above mentioned, an adjacent gun-port, or where, from the vicinity of the next beam, there is not space for the arms of two lodging knees.—Hanging Knees, are those which, from their situation under a deck, appear to support the beams.—Iron Knees, are frequently used in all the various applications instead of wooden ones, particularly in the French ships, on account of the scarcity of timber fit for the purpose.— Lodging Knees, are fixed horizontally in the ship's frame, hav. | K. N.O k N o 543 DICTIONARY OF MECHANICAL SCIENCE. ing one arm bolted to the beam, and the other across two or three of the timbers.—Standard Knees, are those which, being upon a deck, have one arm bolted down to it, and the other pointing upwards, secured to the ship's side; such, also, are the bits and channels.-Transom Knees. See TRANSOM. KNEE of the Head, a large flat piece of timber, fixed edge- ways upon the foremost part of a ship's stem, and supporting the ornamental figure or image placed under the bowsprit. The knee of the head, which may properly be defined a conti- nuation of the stem, as being prolonged from the stem for- wards, is extremely broad at the upper part, and accordingly composed of several pieces united into one. It is let into the head, and secured to the ship's bows by strong knees fixed horizontally upon both, and called the cheeks of the head: The heel of it is scarfed to the upper end of the fore-top, and it is fastened to the stem above by a standard knee. Besides supporting the figure of the head, this piece is otherwise use- ful as serving to secure the boom or bumkin, by which the fore- tack is extended to windward, and by its great breadth pre- venting the ship from falling to leeward when close-hauled, so much as she would otherwise do. It also affords a greater security to the bowsprit, by increasing the angle of the bob- stay, so as to make it act more perpendicularly on the bow- sprit. The knee of the head, is a phrase peculiar to shipwrights; but, by seamen, it is called the cut-water. See, CUT-water. KNIFE, a well-known instrument, made for cutting, and adapted in form to the uses for which it is designed. Knives are said to have been first made in England in 1563, by one Matthews, on Fleet Bridge, London. The importation of all sorts of knives is prohibited. tº º KNIGHT, properly signifies a person, who, for his virtue and martial prowess, is by the king raised above the rank of gentlemen into a higher class of dignity and honour. The ce- remonies at the creation of knights have been various: the prin- cipal was a box on the ear, and a stroke with the sword on the shoulder; they put on him a shoulder belt, and a gilt sword, spurs, and other military accoutrements; after which, being armed as a knight, he was led to the church in great pomp. Camden describes the manner of making a knight bachelor among us, which is the lowest, though the most ancient order of knighthood, to be thus: the person kneeling was gently struck on the shoulder by the prince, and accosted in these words, “Rise,” or “Be a knight in the name of God.” For the several kinds of knights among us, See Banneret, Baronet, Bath, Garter, &c. KNIGHTS of the SHIRE, or Knights of Parliament, in the British polity, are two knights, or gentlemen of estate, who are elected on the king’s writ, by the freeholders of every county, to represent them in parliament. The qualification of a knight of the shire is, to be possessed of 600l. per annum in a freehold ©State. KNIGHT-HEADS, also denote in a merchant ship two strong frames of timber, fixed on the opposite side of the main- deck, a little behind the fore-mast, which support and enclose the ends of the windlass, which accordingly is turned therein as upon an axis: as each of these is formed of two pieces, they may be occasionally separated, in order to take off the turns of the cable from the windlass, or replace them upon it. They are frequently called the bitts, and then their upper parts, only are denominated knight-heads, which being formerly embellished with a figure, designed to resemble a human head, gave rise to a name they have ever since retained. See WINDLAss. KNight-heads, was formerly a name given to the lower jear-blocks, which were them no other than bitts, containing several sheaves, and nearly resembling our present top-sail sheet-bitts. KNITTLE, a small line composed of two or three rope- yarns, either plaited or twisted, and used for various purposes, particularly to fasten the service on the cable, to sling the sailors’ hammocks, to reef the sails by the bottom, &c. KNittle, is also a name given to the loops or buttons of a | bonnet. ~ KNOCK-OFF, an order to cease any work. KNOT, a large knob formed on the extremity of a rope, generally by untwisting the ends thereof, and interweaving them regularly among each other: of these there are several sorts, differing in form, size, and name, as shroud knot, stop- per knot, overhand knot; single wall knot, wale knot, or wal- nut; double wall knot, wale knot, or walnut ; diamond knot, kop knot, reef knot. The bow-line knot is...so firmly made and fastened to the crengles of the sails, that they must break, or the sails split, before it will slip. The sheep-shank knot serves to shorten a rope without cutting it, which may be presently. loosened. The wale knot is so made with the lays of a rope, that it cannot slip, and serves for sheals, tacks, and stoppers. The knots are generally used to act as a button in preventing the end of the rope from slipping through an eye, or through the turns of a laniard, by which they are sometimes made fast to other ropes. * - KNot, also signifies the manner of tying two ropes together, or the end of a rope to a bight in the same. - KNot, also implies a division of the long-line, which answers to half a minute, as a mile does to an hour, i.e. rim of a mile ; hence we say, the ship was going eight knots, which signifies eight miles per hour. KNOUT, the name of a punishment inflicted in Russia, with a kind of whip called knout, and made of a long strap of lea- ther prepared for the purpose. ers dexterously carry off a slip of skin from the neck to the bottom of the back laid bare to the waist, and repeating their blows, in a little while rend away all the skin of the back in parallel stripcs. -In the common knout, the criminal receives the lashes suspended on the back of one of the executioners; but in the great knout, which is generally used on the same occasions, as racking on the wheel in France, the criminal is raised into the air by means of a pulley fixed to the gallows. and a cord fastened to the two wrists tied together; a piece of wood is placed between his two legs, also tied together, and another of a crucial form under his breast; sometimes his hands are tied behind over his back, and when he is pulled up in this position, his shoulders are dislocated. The execution- ers can make this punishment more or less severe; and it is said, are so dexterous, that when a criminal is condemned to die, they can make him expire at pleasure, either by one or several lashes. - KNOWLEDGE, is defined by Mr. Locke to be the percep- tion of the connexion and agreement or disagreement and repugnancy of our ideas. - # In his fifth book of the Grammar of Logic and Intellectual Philosophy, the Editor has given a Syllabus of the Philosophy of Human Knowledge, and the following Prospectus is, there- fore, but a very limited draught of that abstract. The Words History, PHILosophy, and Poetry, taken in their most extensive meanings, may be said to comprehend every branch of human knowledge. But history addresses itself to the Memory; Philosophy, to the Understanding; and Poe- try to the Imagination. The Philosophy of Human Knowledge will therefore be divided into three great compartments, adapt- ed to these three faculties—the Memory, the Understanding, and the Imagination. According to this arrangement, Human Knowledge may be considered as it is addressed to the memo- ry, under the title of History. But history is a word of exten- sive import, and suggests a subdivision of its materials into three parts, under the respective titles of Sacred, Civil, and Na- tural History. Under the first title, ecclesiastical history, the science of language arranges the narrative parts of revelation —the history of the Jews, the propagation and the progress o. Christianity, &c. Under the second title—Civil, or Profane History, Literary History, Memoirs, Annals, Biography, Anti- quities, Chronology, and Geography, demands attention. The third title, which Lord Bacon calls Narrative, comprehends the following subordinate divisions, viz.-1. Productions of Na- ture, as the phenomena of the Heavens, the Atmosphere, and the Earth; 2. The three Kingdoms of Nature, as Minerals, Vegetables, and Animals; 3. A Delineation of the Mechanical Arts and Manufactures. - - The Philosophy of Human Knowledge, addressed to the un- derstanding, views all the sciences and the theories of all the arts, or, in other words, the Philosophy of the knowledge of mind and the knowledge of body. * , In considering knowledge as referring to mind unconnected with body, or to mind and body connected, or to body uncon- With this whip the execution- * 544 K U P K. N. O D1GTIONARY OF MECHANICAL SCIENCE. nected with mind, we are led to the contemplation of the doc- trines and principles which result from those attributes which revelation assigns to. Deity, and thence to a delineation of the Philosophy of Natural Religion, and part of the science of Metaphysics. - - ; - . . The branches of knowledge relative to man and human nature, which belong to this division, respect either the faculties of his mind, or the use which he makes of those faculties: first, in ac- quiring and communicating knowledge; and secondly, in ac- quiring happiness. Thus we launch into a philosophical view of those sciences which embrace the general history of the faculties of the mind, and the exertions of those faculties in all that is valuable, in Logic, in Rhetoric, and in Morality. The terms logic and rhetoric are generally applied to intimate the philosophy of those arts in the cultivation of Taste, Criticism, the Belles Lettres, or polite Literature; and as their study qua- lifies us to determine the merits of compositions or works of art. Morality, or the science of happiness, divides itself into two dis- tinct branches; one relative to individuals, and the other rela- tive to communities. The former comprehends, many impor- tant topics of investigation, founded on the principles of virtue, the laws of human conduct, obligations to integrity, and duties to our Creator, our neighbour, and ourselves. The second; the morality that regards communities, constitutes the science of politics, which resolves itself into three branches; the first containing the laws of peace and war, or the rules which guide the intercourse of communities, founded on the practice of civi- lized nations, and the dictates of equity; the second deline- ating the different civil governments which have been contrived or adopted, to secure the safety of states, with the prosperity and comfort of individuals; and the third exhibiting economi- cal arrangements, or the laws which punish crimes, and encou- rage industry, and which protect and cherish commerce and the arts. . - - r - Human Knowledge, relative to body, animated or inani- mate, is divided into three branches;–the first contains the metaphysics of body, or the philosophy of its general properties, extension, solidity, impenetrability, motion, &c. The second, regarding the surfaces of bodies, investigates the importance of the truths, and the value of the evidence, furnished by Arith- metic, Geometry, and Natural Philosophy. The third, viewing the internal parts of bodies, explains those branches of phi- losophy which regard, first, the general laws or properties of bodies; secondly, the internal structure of animals, with their diseases and cures; and thirdly, the ingredients or component parts of bodies. The first constitutes the science of Natural History; the second, Medicine; and the third, Chemistry. . The Philosophy of Human Knowledge, addressed to the Imagination, may be briefly quoted in the successive terms, Poe- try, Sculpture, Architecture, Painting, Gardening, and Music. The term Poetry is not, however, restricted to metrical com- positions, but includes all ornamental and figurative composi- tions, addressed to the imagination and the heart. Under the title Sculpture, are comprehended the productions of antiquity which have served as models and standards of excellence to the moderns, and called forth their exertions to rival the age of Peric- les, that aera of luxury and splendour, which gave it the title of the Golden Age of the arts in Greece. Statuary appears in three splendid aeras; first, when it displayed itself with such surpris- ing lustre in the productions of the antique statues; secondly, when it was revived under Leo X. ; and lastly, in our own times, wherein we behold geniuses animated by a similar spirit of taste, and a similar solidity of judgment, as formed the Grecian pain- ters Apelles and Zeuxis, and the sculptors Phidias and Praxi- teles. On principles somewhat analagous, Knowledge extends to Architecture and Painting, but of Gardening and Music antiquity furnishes no standards or models of taste to the moderns, with which their acquirements may be compared. Confining our views to the reality of knowledge, it is evident that the mind knows not things immediately, but by the inter- vention of the ideas it has of them. Our knowledge therefore, is only real, so far as there is a conformity between the reality of things and our ideas of that reality. Now there are two classes of ideas in which this agreement may be traced, and these are, our simple ideas, and those which are generally denominated complex. tà As the human mind can by no means make to itself simple ideas, it is obvious that they must be the effect of things ope- rating upon it in a natural way, and producing therein those perceptions, which by the will and appointment of God, they are adapted to produce. Hence, it follows, that, simple ideas are not the fictions of fancy, but the natural and regular pro- duction of things without us, really operating upon us, and carrying with them all the conformity our state requires, which is to represent things under those appearances they are fitted to produce in us. Thus the idea of whiteness, as it is in the mind, exactly answers that power which is in any body to pro- duce it there. Similar remarks may be made respecting all our simple ideas; and this conformity between them and the existence of things, is sufficient for the purposes of real know- ledge. * 4 - All our complex ideas, excepting those of substances, which are involved in much obscurity, being archetypes of the mind's own, making, and not referred to the existence of things, as to their originals, cannot want any conformity necessary to real knowledge ; for that which is not designed to represent any thing but itself, can never be capable of any wrong represen- tation. ... * * - . s - Hence it appears, that our simple ideas produced by things without us, operating upon the senses, furnish the sterling materials of all our knowledge. The mental storehouse being thus enriched, the mind can combine, arrange, and associate them at pleasure, and thus trace agreements or disagreements in the combinations which it forms. By these means error can be detected, new truths elicited, and in this rich and fertile region, fancy can exercise her creative energy, and give birth to works of taste and genius. . . • , . - Whatever ideas we havé, the agreement we find they have with others will be knowledge. "If those ideas be abstract, it will be general knowledge; but to make it real concerning sub- stances, the ideas must be taken from the real existence of things. Wherever, therefore, we perceive the agreement or disagreement of our ideas, there is certain knowledge; and wherever we are sure those ideas agree with the reality of things, there is certain, real knowledge. * , KORAN, or ALKoRAN, the name of the book held equally sacred among the Mahometans, as the Bible is among Chris- tians. The general aim of the Koran was, to unite the profes- sors of the three different religions then followed in Árabia, Idolaters, Jews, and Christians, in the knowledge and worship of one God, under the sanction of certain laws, and the out- ward signs of ceremonies, partly of ancient, and partly of novel institution, enforced by the consideration of rewards and punishments, both temporal and eternal; and to bring all to the obedience of Mahomet, as the prophet and ambassador of God. The chief point therefore inculcated in the Koran is the unity of God, to restore which the prophet confessed was the chief end of his mission. The rest is taken up in prescribing neces- . sary laws and directions, frequent admonitions to moral and di- vine virtues, the worship and reverence of the Supreme Being, and resignation to his will. The style of the Koran is generally beautiful and fluent, con- cise, but often obscure, adorned with bold figures; enlightened with florid and sententious expressions; and in many places, especially where the majesty and attributes of God are descri- bed, sublime and magnificent. Among Mahometans this book is held in the greatest reverence and esteem. They suppose it to be of divine original, eternal, and uncreated; and that it was revealed to Mahomet by the angel Gabriel; dare not touch it without being first washed, or legally purified ; and read it with great care and respect. They swear by it, take omens from it on all weighty occasions, carry it with them to war, write sentences of it on their banners, adorn it with gold and precious stones, and do not suffer it to be in the possession of any who hold a different religion. It has been translated into English. - KOS, in Jewish Antiquity, a measure of capacity, containing about four cubic inches; this was the cup of blessing, out of which they drank when they gave thanks after solemn meals, like that of the passover. - - KUPFERNICKEL, is a sulphuret of nickel, and is general- ly compounded of nickel, arsenic, and Sulphnret of iron. - L A C L A C 545 DICTIONARY OF MECHANICAL SCIENCE. L. L. or 1, the eleventh letter of our alphabet; a numeral deno- ting 50; and with a dash over it, 50,000. LA, in Music, the syllable by which Guido denotes the last sound of each hexachord; if it begins in C, it answers to our A, if in G to E.; and if in F to D. LABDANUM, or LADANUM, is a resin obtained from the sur- face of the cystus Creticus, a shrub which grows in Syria, and the Grecian islands. It is collected while moist, by drawing over it a kind of rake, with thongs fixed to it, from which it is afterwards scraped. When it is very good, it is black, soft, and has a fragrant odour and a bitterish taste. Water dissolves about a twelfth part of it, and the matter taken up possesses gummy properties. When distilled with water, a small quan- tity of volatile oil arises. Alcohol may also be impregnated with the taste and odour of labdanum. LABEL, in Navigation, a thin brass ruler used in taking altitudes. In Law, a slip of paper or parchment that holds the seal. In Pharmacy, directions for the use of medicine. LABIAL LETTeRs, those pronounced chiefly by means of the lips. LABORATORY, in Military affairs, signifies that place where all sorts of fireworks are prepared, both for actual ser- vice and for experiments, viz. quick matches, fuzes, port-fire, grape shot, case shot, carcasses and grenades, cartridges, shells filled, and fuzes fixed, wads, &c. &c. LABORATORY, in Chemistry, the room in which the artist keeps his utensils, and makes his experiments. LABOURING, implies pitching or rolling heavily in a tur- bulent sea, an effect by which the masts and hull of the ship are greatly endangered; because, by the rolling motion, the masts strain upon their shrouds with an effort which increases as the sine of their obliquity; and the continual agitation of the vessel often loosens her joints, and makes her extremely leaky. LABYRINTH, among the ancients, was a large intricate edifice cut into various aisles and meanders, running into each other, so as to render it difficult to get out of it. There is mention made of several of those edifices among the ancients; but the most celebrated are the Egyptian and Cretan labyrinths. LAC is a resinous substance, the production of an hemip- terous insect, which is found on three or four different kinds of trees in the East Indies. The head and trunk of the lac insect seem to form one uniform, oval, and compressed red body, about the size of a flea. The antennae are thread-shaped, and half the length of the body. The tail is a little white point, from whence proceed two horizontal hairs as long as the body. These insects pierce the small branches of the trees on which they feed; and the juice that exudes from the wounds is formed by them into a kind of cells, or nidus for their eggs. Lac is imported into this country adhering to the branches in small transparent grains, or in semi-transparent flat cakes. Of these the first is called stick lac, the second seed lac, and the third shell lac. On breaking a piece of stick lac, it appears to be com- posed of regular honeycomb-like cells, with small red bodies lodged in them ; these are the young insects, and to them the lac owes its tincture, for when freed from them its colour is very faint. Seed lac is the same substance grossly pounded, and de- prived of its colouring matter, which is used by dyers and for other purposes; and shell lac is the cells liquefied, strained, and formed into thin cakes. LAC Sulphuris, in Medicine, a sulphur, separated by acid from its alkaline solution, which renders it milder. See SULPHUR. LACCIC Acip, in Chemistry, a white or yellowish produc- tion of insects, called white lac. Some of this substance, brought from Madras, was analyzed, and found to bear a con- siderable analogy to bees’ wax. The component parts of this acid are carbon, hydrogen, and oxygen. LACE, in Commerce, a work composed of many threads of gold, silver, or silk, interwoven one with the other, and worked upon a pillow with spindles, according to the pattern designed; ** * the open work being formed with pins, which are placed and displaced as the spindles are moved. For cleaning gold lace and embroidery when tarnished, alkaline liquors are not to be used, for they corrode the silk, and change or discharge its colour. Soap also alters the shade of certain colours. But spirit of wine may be used without any danger of its injuring either the colour or quality; and in many cases proves as effectual for restoring the lustre of the gold, as the corrosive detergents. 4 LAce Bone, a lace made of fine linen, thread, or silk, much in the same manner as that of gold and silver. The pattern of the lace is fixed upon a large round pillow, and pins being stuck into the holes or openings in the pattern, the threads are inter- woven by means of a number of bobbins made of bone or ivory, each of which contains a small quantity of fine thread, in such a manner as to make the lace exactly resemble the pattern. LACERTA, the Lizard, was added by Hevelius to the old constellations. Boundaries and Contents: north by Cepheus, west by Cygnus, south by Pegasus, and east by Andromeda. In general it lies between Cygnus and Andromeda, and contains sixteen stars, three of the fourth magnitude, the remainder being smaller. LACHRYMATORY, in antiquity, a vessel wherein were collected the tears of a deceased person’s friends, and pre- served along with the ashes and urn. They were small glass or earthen bottles, chiefly in the form of phials. At the Roman funerals, the friends of the deceased, or the praeficae, women hired for that purpose, used to fill them with their tears, and deposit them very carefully with the ashes, in testimony of their sorrow, imagining the mancs of the deceased were thereby greatly comforted. Many specimens of them are preserved in the cabinets of the curious, particularly in the British Museum. LACK of RUP'ees, is 100,000 rupees; which, at 2s. 6d. each, amounts to £12,500 sterling. LACTATES, combinations of earths and alkalies, &c. with the lactic acid. LACTATION, among medical writers, denotes the giving suck. The mother’s breast, if possible, should be allowed the child, at least during the first month; for the child is thus peculiarly benefited by what it sucks, and the mother is pre- served from more real inconveniences than the falsely delicate imagine they would suffer by compliance here with ; but if, by reason of an infirm constitution, or other causes, the mother cannot suckle her child, let dry-nursing, under the mother's eye, be pursued.—When women lose their appetite by giving suck, both the children and themselves are thereby injured : wet nurses are to be preferred, who, during the time they give the breast, have rather an increased appetite, and digest more quickly; the former are apt to waste away, and sometimes die consumptive. In short, those nurses with whom lactation may for a while agree, should wean the child as soon as their appe- tite lessens, their strength seems to fail, or a tendency to hysteric symptoms is manifest. When the new-born child is to be brought up by the mother’s breast, apply it thereto in ten or twelve hours after delivery : thus the milk is sooner and more easily supplied, and there is less hazard of a fever than when the child is not put to it before the milk begins to flow of itself. If the mother does not suckle her child, her breasts should be kept so warm with ſlannel, or with a hare-skin, that a constant perspiration may be Sup- ported; thus there rarely will arise much inconvenience from the milk. The child, notwithstanding all our care in dry nursing, sometimes pines if a breast is not allowed. In this case a wet nurse should be provided; if possible, one that has not been long delivered of a child. She should be young, of a healthy habit, and an active disposition, a mild temper, and with breasts well filled with milk. If the milk is good, it is sweetish to the taste, and totally free from saltness; to the eye it appears thin, and of a bluish cast. º © 6 Z 546 L A D L. A D DICTIONARY OF MECHANICAL SCIENCE. LACTIC Acid. By evaporating sour whey to one-eighth, filtering, precipitating with lime-water, and separating the lime by oxalic acid, Scheele obtained an aqueous solution of what she supposed to be a peculiar acid, and called it lactic acid. trillan, Lagrange has since examined it more narrowly, and concluded it. to consist of acetic acid, muriate of potash, a | small partion of iron, and animal matter. LACTIFEROUS, an appellation given to plants abounding with a milky juice, as the sowthistle and the like. The name of lactiferous, or lactescent, is given to all those plants which abound with a thick coloured juice, without regarding whether it is white or not. Most lactiferous plants are poisonous, except those with compound flowers, which are generally of an innocent quality. Of the poisonous lactescent plants the most remarkable are sumach, agaric, maple, burning thorny plant, cassada, celandine, spurge, prickly poppy; and the plants of the natural order contortae, as swallow-wort, apocynum, cynanchum, and cerbera. The bell-shaped flowers are partly noxious, as cardinal flower; partly innocent, as campanula. Among the lactescent plants with compound flowers, that are innocent in their quality, may be mentioned dandelion, picris, hyoseris, wild lettuce, gum succory, hawkweed, bastard hawk- weed, hypochoeris, goat's-beard, and most species of lettuce; we say most species, because the prickly species of that genus are said to be of a very virulent and poisonous nature; though Mr. Lightfoot denies this, and affirms, that they are safe and gentle opiates, and that a syrup made from the leaves and stalks is much preferable to the common diacodium. LACTOMETER, the name of an instrument used for the purpose of ascertaining the different qualities of milk, from its specific gravity compared with water, and its degrees of tem- perature under various circumstances. It was invented, by M. Dicas, mathematical instrument maker, of Liverpool, but is yet in its infancy. -- LACTUCA, Lettuce, a genus of the syngenesia polygamia aequalis class and order of plants. Natural order of compo- sitae semiflosculosae. Cichoraceae Jussieu. There are eleven species; of L. sativa, or common garden lettuce, there are fifteen varieties. LACUNAR, in Architecture, an arched roof or ceiling, more especially the planking or flooring above porticos or piazzas. LADDER, a well-known convenience, of which there are a great number. In a ship, ladders serve as stairs whereby to ascend or descend from one deck to another; and are dis- tinguished by epithets, according to the several hatchways or other parts of a ship wherein they are situated. Scaling LADDERs, in the Military art, are used in scaling when a place is to be taken by surprise. They are made several ways: in England, they are made of flat staves, so that they may move about their pins, and shut like a parallel ruler, for conveniently carrying them: the French make them of several pieces, so as to be joined together, and to be made of any necessary length; sometimes they are made of single ropes, knotted; at proper distances, with iron hooks at each end, one to fasten them up the wall above, and the other in the ground; and sometimes they are made with two ropes, and Staves between them, to keep the ropes at a proper distance, and to tread upon. When they are used in the action of Scaling Walls, they ought to be rather too long than too short, and to be given in charge only to the stoutest of the detach- ment. - Thompson's Mechanical LADDeR.—This ladder is a very inge- nious contrivance, invented by a gentleman of the name of Thompson, and called by him the mechanical ladder. A A in the accompanying sketch, denote parallel ropes stretched and placed for the purpose of steadily conducting a seat or carriage C, in which a man may sit, and descend from the upper to the lower points of A. A.; these lines may be placed either in a perpendicu- lar or inclined position; but an inclined position, forming an angle of about twenty degrees with the perpendicular, will in general be found most eligible. The carriage C may be con- nected by ropes, by rings, loops, or any kind of bearing parts which will confine it to a regular ascent and descent. It is connected with the counterpoise or place of reaction, E, by a rope passing over the pulley D. B B represents a ladder for the workmen to ascend. f The manner of working this machine is as follows: the workman ascends by B B, and places himself in the carri- age C, in which his weight (by preſer- ence) forms nearly an equilibrium with the weight E, which may, for example, be imagined a basket of coals. . Either by taking hold of the leading ropes, or of a rope passing downwards for that purpose, he causes the carriage to de- scend briskly, which at the same time brings up E. He then quits the carri- age, and at that time, E (which we may suppose to have been emptied by ano- ther assistant by reversing it (or other- wise) being somewhat heavier than C, descends again, and raises C to its first situation, and by the time E is again filled, the workman is ready at the top of the ladder, where he enters the car- riage, and raises a second load; and in this way the work may be continued at pleasure. It is evident that this work may be performed by two or more workmen ascending and descending in succession by means of the same lad- --~~- der ; or, if more convenient, by more Iadders than one, and in case it should be desired to lift the body E through a greater space than is to be ascended by the workmen upon B B, the purpose may be effected by fixing D higher, and causing two carriages to descend in succession along the ropes A A, though this plan is not particularly to be recommended. The rope D E may also be wound on a barrel, and the rope D C on another, or similar barrel, both on the same axis. The parts of the machine A A, may instead of ropes be wooden or metallic sliders. This machinery, the inventor observes, is applicable to draw-. ing, driving, forcing, impressing, or moving bodies of every de- scription, and that in such applications of it, no other variations in the construction, connexion, or method of working it, will be needful, than such as any person possessing an ordinary acquaintance with mechanical operations, may execute with facility. The vulgar objection to the plan is ascending the ladder, yet this is its chief recommendation, for it is the easiest method of raising a weight. The truth of this assertion will be ascertained from the following stateinent. - If it be required to raise a sack of corn, a basket of coals, or any other equal weight, to the height of forty feet, (more or less) no method can be so easy to the person who is to raise the weight, as to ascend stairs or a ladder unencumbered, and to raise the sack, &c. by his own weight. By no other exertion of his own, nor by the assistance of any mechanical powers, can he perform the same operation in the same time. It must consequently be the easiest mode of raising a weight, or it could not be done in the shortest time. If it is easier in one operation, it must be equally so in any number of operations. If it is easier for one man, it must be equally so where any num- ber of men can be employed to work together in raising heavy weights, and where this principle can be introduced. If it is easier, it must be cheaper. The labour consists in ascending the ladder, and in this exertion the man's muscular powers are all in action at the same time; not partially used, as in most other modes of raising weights. His strength may be combined with his gravity in his descent, and if opposed by the least possible friction, he cannot work with greater advantage. - Desaguliers states the maximum of a man's power as under: One man 500 pounds, 12 feet, 1 minute. The weight raised was water in a bucket. The man, who was very powerful, as- cended stairs with a weight about his own person, which, toge- ther with his own, was equal to the water, and placed himself. on or in an empty bucket, which was suspended by a rope pass- ing over a pulley, and fastened to the bucket containing, the water below, and raised it in the time. The man was so ex- hausted, that he could not repeat the operation. L. A D L A M 547 DICTIONARY OF MECHANICAL SCIENCE. The following experiment has often been exhibited by means of the present invention. One man, 1500 pounds, 12 feet, 1 minute. And this difference arises from the man’s strength being combined with his gravity, and the facilities which the two parallel ropes afford him, to gain velocity by a slight exer- tion of his arms to arrest his descent, and quickly to re-ascend the ladder. If a man weighs 14 stone, or 196 pounds, and ascends the ladder eight times in a minute (which almost any active man may do) it is clear that he can raise eight times his own weight, or 1568 pounds. The steps of the ladder being one foot apart (that stride being found most agreeable to the labourers) if a man ascends as slowly as possible, that is, at the rate of one foot in each second, he will ascend five times in a minute to the height of twelve feet; and if he weighs twelve stone, or 168 pounds (the average weight of a labouring man) he will raise his weight five times, or 840 pounds in that time. He will probably con- sume ten seconds in ascending, and one or two seconds in de- scending and raising the weight. He cannot work slower. Applying this rate of work, the result of one man's power for one hour in raising the under-mentioned articles will be, Coals, . . . . . . . . . . . . . . . . . . . . . . 10 chaldrons 20 feet. Malt, Barley, Oats, &c. . . . . . . 90 quarters 20 feet. Bricks, . . . . . . . . . . . . . . . . . . . . . 6000 quarters 20 feet. Water, . . . . . . . . . . . . . . . . . . . . . 3000 gallons 20 feet. When the distance is doubled, the weight raised during the same time, will be one half—The following weights have already been raised: - Men Feet. Hours. Min. Coals* 240 chaldrons,...... 2 6} to 21 17 7 Brickst 22,000..... e e º 'º e º º 2 40 . . . . 7 30 Ditto, 6000 . . . . . . . . . . . . . . 2 40 . . . . I 0 Ditto, 1500 .............. 2 40 . . . . 0 12 There are four men employed to raise a basket of coals on the river Thames, and six on many parts of the coast. It has hitherto (in 1810) been found impossible to establish, or even try this plan on board of any collier in the river Thames; but it has been used at Brighton, where one of Lathmar's ships was discharged by it, with four men short of the usual complement, and in rather less than the usual time; only four men being employed to work in the hold, they could not fill the basket faster, or the vessel would have been discharged in half the usual time. The two men who worked the machine, waited nearly half of the time for a supply, and could have raised 20 chaldrons per hour instead of 12, the quantity with which they were supplied. This plan has for a considerable time been established at the East India Docks, where all the Indiamen are discharged by it. The first ship on board of which it was tried, was the Fort William, laden with bales of cotton, weighing about two hundred and three-quarters each. The bales were raised by two men only. The Porcher was delivered at the same time by the old plan, and contained a similar cargo; each bale was raised by six men. From the Fort William 5532 bales were delivered in 17 days; from the Porcher, 5022 in 20 days; leav- ing an advantage of four men, three days, and a surplus of 510 bales in favour of the Fort William. The men who raised the bales on board the Fort William stood still nearly half the time, as the weigher could not pass the bales quicker through the Scales. The men who raised the bales from the Porcher were fully employed, and exerted themselves to the utmost, with the hope of preventing the establishment of the new plan. The inventor of this machine took out a patent for it, the Specification of which is dated March 20, 1809. He offered the use of his invention to the City of London, without the reser- vation of any remuneration to himself, stipulating only that a | part of the saving arising from it might be devoted to a fund for bettering the present and future condition of the men, to whose labours it was chiefly applicable; so as eventually to establish some asylum or provision for them and their families, when age or accident might have disabled them from working. * The coals in baskets similar to those used on the river Thames. t. The bricks, two hods, or about 34 at a time. The advantages derivable from the machine, were confirmed before Sir Charles Flower, the Lord Mayor in 1809, by the affidavits of two men who used it; by which it appeared that they had actually been able to perform with it more work than had ever been done by any four men in the same time. The inventor, in his memorial to the Lord Mayor and Court of Aldermen, observes, “that any man may work by his plan, no drilling being required; and as it is merely an improvement of the old principle, it should not be regarded as the substi- tution of any other power for that of man, as steam, horse- power, &c.” 4. * - The foregoing statements we have extracted from a very useful work in two volumes, called “The Mechanic, or Com- pendium of Practical Inventions,” in which a description of a great number of very useful inventions may be found. LADEN, the state of a ship when she is charged with a weight or quantity of materials equal to her tonnage or burden. If the goods, with which she is laden, be extremely heavy, her burden is determined by the weight thereof; but if light, she | carries as much as she can stow, for the purposes of navigation. As a ton measure is generally estimated at 2000lbs in weight, a vessel of 200 tons ought accordingly to carry a weight equal to 400,000 pounds; therefore, when the matter of which the cargo is composed is specifically heavier than the water in which she floats, or, in other words, when the cargo is so heavy that she cannot float high enough with so great a quantity of it as her hold will contain, a diminution thereof becomes absolutely necessary. - LADY. This title is derived from two Saxon words, which words have in time been contracted into the present appella- tion. It properly belongs only to the daughters of earls, and all of higher rank; but custom has made it a word of com- plaisance for the wives of knights, and of all eminent women. LAETIA, a genus of plants belonging to the polyandria class, and in the natural method ranking with those of which the order is doubtful. LAGURUS, a genus of plants belonging to the triandria class, and in the natural method ranking under the fourth order, gramina. - LAITY, the people, as distinguished from the clergy; see CLeRGY.. The lay part of his majesty’s subjects is divided into three distinct states; the civil, the military, and the maritime. See CIVIL, MILITARY, and MARITIME. LAKE, a collection of waters which usually receives and dis- charges rivers. Of lakes, which both receive and emit rivers, we reckon three kinds, as the quantity they emitis greater, equal, or less than they receive. If it be greater, it is plain that they must be supplied by springs at the bottom ; if less, the surplus of the water is probably spent in exhalation ; and if it be equal, their springs just supply what is evaporated by the sun. Lakes are also divided into those of fresh water, and those of salt. Large lakes answer the most valuable purposes in the northern regions. • LALANDE, Joseph J ERo ME LE FRANCAIs, a celebrated French astronomer, was born at Bourg, in the department of L'Ain, in July, 1732. He was first intended for the bar, but his genius having been very early directed to astronomical sub- jects, his first intention was given up ; and he followed his astronomical pursuits under the celebrated Lemonier, with the greatest success. Lalande was also an associate of the princi- pal learned societies in Europe, and was for many years the centre of communication amongst the most celebrated of their members. After a long and useful life in the pursuit of sci- ence, he died on the fourth of April, 1807, being then in the 75th year of his age. LAMA, the sovereign pontiff, or rather god, of the Asiatic Tartars, - * . & LAMB, THE BARometz, or TARTARIA N.—Whoever has per- used the accounts of early travellers, must recollect the stories that have been copied into our ancient herbals, of Tartarian sheep growing upon stems in the earth, and thence devouring all the vegetables that came within their reach. A tale of this kind could not fail to attract the attention of the immortal father of modern botany, who took considerable pains to investigate it, and ascertained that, in the eastern part of Chinese Tartary, there is a species of fern, furnished with 548 L. A M L. A M DictionARY of MechANICAL science. thick tubers, which being surrounded, on all sides with yellow wool, and thin chaffy scales, are often raised so high above the ground, that the roots beneath bear some resemblance to legs fixed in the soil. The genus of t - : - 3 & {{ſ this fern has not * sº yet been ascer- sº tained. but it is §§§ known that the sº §§§ d §§ roots sprea §§ sº º §§ \\\ round to a con- - §§ \ siderable ex- &##$$$. º, )} tent, and per- haps prevent all other plants \º growing nearit: Nº it is not at all g surprising that the imagination of the superstitious and ig- morant should transform this curious vegetable into a voracious sheep. A specimen of such botanical curiosity could not pass unnoticed by the observant but romantic Darwin; and accord- ingly we find him speaking of it in the following terms. E’en round the pole the flames of love inspire, And icy bosoms feel the secret fire Cradled in snow, and fanned by arctic air, Thine, gentle Barometz' thy golden hair; Rooted in earth each cloven foot descends, And round and round her flexile neck she bends ; Crops the gray coral moss, and hoary thyme, Or laps with rosy tongue the melting rime, Eyes with mute tenderness her distant dam, Or seems to bleat, a vegetable lamb. LAMBERT, John Hen RY, an eminent mathematician and astronomer, was born at Muhlhausen in Sundgaw, belonging to Switzerland, Aug. 29, 1728. His parents being poor, he had great difficulties to contend with in the pursuit of his studies, which he nevertheless prosecuted with unbounded success. Most of his mathematical pieces were published in a collected form by himself, in three volumes, in which almost every branch of mathematical science has been enriched with his improve- ments and additions. Lambert died in 1777, in the 50th year of his age. LAMINAE, in Physics, are extremely thin plates, of which solid bodies are supposed to be made up. These are indeed rather ideal than real; but such a conformation is frequently supposed, for the sake of simplifying the solution in a great variety of physical problems. LAMMAS DAY, the first of August, so called, as some will have it, because lambs grow out of season, as being too big. Others derive it from a Saxon word, signifying “loaf-mass,” because on that day our forefathers made an offering of bread made with new wheat. On this day, the tenants who formerly held lands of the cathedral church in York, were bound by their tenure to bring a lamb alive into the church at high mass. LAMP, a vessel containing oil, with a lighted wick. From experiments made in order to ascertain the expense of burning chamber oil in lamps, it appears, that a taper lamp, with eight threads of cotton in the wick, consumes in one hour #5 oz. of spermaceti oil at 2s. 6d. per gallon; so that the expense of burning 12 hours is 457 farthings. This lamp gives as good a light as the candles of eight and ten in the pound; it seldom wants snuffing, and casts a strong and steady light. A taper, chamber, or watch lamp, with four ordinary threads of cotton in the wick, consumes 0° 1664 oz. of spermaceti oil in one hour; the oil, at 2s. 6d. per gallon, makes the expense of burning 12 hours only 2:34 farthings. Of lamps there are many constructions; a few of the most remarkable, yet useful, 2FC 2– Argand's LAMP. This is a very ingenious contrivance, and the greatest improvement in lamps that has yet been made. It is the invention of a citizen of Geneva; and the principle on which the superiority of the lamp depends, is the admission of a larger quantity of air to the flame than can be done in the common way. This is accomplished by making the wick of a circular form, by which means a current of air rushes through the cylinder on which it is placed with great force; and, along with that which has access to the outside, exciting the flame to such a degree that the smoke is entirely consumed. Thus both the light and heat are prodigiously increased, at the same time that there is considerable saving in the expense of oil, the combustion being exceedingly augmented by the quantity of air admitted to the flame; and that what in common lamps is dissipated in smoke, is here converted into a brilliant flame. This lamp is now very much in use, and is applied not only to the ordinary purposes of illumination, but also to that of a lamp furnace for chemical operations, in which it is ſound to exceed every other contrivance yet invented. It consists of two parts, viz. a reservoir for the oil, and the lamp itself. The reservoir is usually in the form of a vase, and has the lamp proceeding from its side. The latter consists of an upright metallic tube, about one inch and six-tenths in diameter, three inches in length, and open at both ends. Within this is another tube about an inch in diameter, and nearly of an equal length; the space betwixt the two being left clear for the pas- sage of the air. The internal tube is closed at the bottom, and contains another similar tube about half an inch in diameter, which is soldered to the bottom of the second. It is perforated throughout, so as to admit a current of air to pass through it; and the oil is contained in the space betwixt the tube and that which surrounds it. A particular kind of cotton cloth is used for the wick, the longitudinal threads of which are much thicker than the others, and which nearly fill the space into which the oil flows; and the mechanism of the lamp is such, that the wick may be raised or depressed at pleasure. When the lamp is lighted, the flame is in the form of a hollow cylinder; and by reason of the strong influx of air through the heated metallic tube, becomes extremely bright, the smoke being entirely consumed, for the reason already mentioned. The heat and light are still farther increased, by putting over the whole a glass cylinder nearly of the size of the exterior tube. By diminishing the central aperture, the heat and light are propor- tionably diminished, and the lamp begins to smoke. The access of air, both to the external and internal surfaces of the flame, is indeed so very necessary, that a sensible difference is perceived when the hand is held even at the distance of an inch below the lower aperture of the cylinder; and there is also a certain length of wick at which the effect of the lamp is strongest. If the wick be very short, the flame, though white and brilliant, emits a disagreeable and pale kind of light; and if very long, the upper part becomes brown, and smoke is emitted. The Ball Cock, or Self-regulating LAMP. The principle of this lamp is that of the ball-cock. The manner in which it operates will be immediately understood from a slight consi- deration of the annexed figure of it, in which the several parts are represented in the situations which they respectively assume when the reservoir is empty. Those parts only are noticed which are necessary to explain the manner in which the lamp regulates itself. A is a valve at the bottom of the reservoir, to which is attached an upright stem G, moveable vertically through holes in the projecting pieces of metal m m. To this is attached the 'ball, an air-tight vessel of a globular form, and so light as to A float in oil, (a piece of varnished cork might be substituted.) A bent wire, moveable about as a centre, has one A of its ends soldered to the ball, and Ž the other is in contact with the # valve A. E is the burner, with its à socket, wick, &c. A lid covers the à chamber enclosing the ball float, and which may be removed when neces- sary for the purpose of cleaning the inside. While the parts of the lamp are in the situation just described, let oil be poured into the reservoir. It is manifest, that it will flow through the aperture at the bottom into the chamber containing the hollow ball, which will in consequence float, and be caused to ascend. , Hence the oppo- site extremity of the bent wire will descend, and the valve A will follow it by its own gravity, closing the aperture, and pre- L. A M L A M 549 DICTIONARY OF MECHANICAL SCIENCE. venting the further efflux of oil. As, however, the oil is gra- dually consumed in the burner, it is manifest that the ball will descend, and consequently elevate the opposite extremity of the wire, together with the valve A, thus producing a fresh efflux of oil, until the whole is consumed. This lamp more- over keeps the surface of the oil in the burner always very nearly at the same distance from the flame; it projects, no shadow from itself, and may be supplied with oil while burning. Hydro-Pneumatic LAMP. The discovery of M. Dobereiner of the remarkable action of spungy platinum upon hydrogen gas, has led to the construction of an elegant lamp for producing instantaneous light. This lamp was, we believe, first made for sale by Mr. Garden, of London; but it has since been improved formby, Mr. Adie, optician, in Edinburgh.-[See Plate, MALT-KILNs and LAMPS.] The form given to the lamp by Mr. Garden, is shewn in the plate, fig. 3, where A B is a glass globe, fitting tightly by a ground shoulder into the neck mºn, of another globe or vessel C.D. The globe A B terminates downwards in a hollow neck, m n op, in the lower end of which is placed a small cylinder of zinc op. ; Into the neck of the vessel C D is fitted a brass piece a b c, through which the gas contained in C D can escape at the point c, by turning a cock d. An arm ef slides through h, and carries in a brass box P a piece of spungy platinum, which can be brought nearer to c, or removed from it, by sliding the arm ef through k. If we now pour diluted sulphurie acid into the vessel A B by the mouth at S, it will descend through the neck mºn, compressing the air in C D, if the cock d is shut. The diluted acid will now act upon the ring of platinum, op, and produce hydrogen gas, which, after the common air in C D is jet off, will gradually fill the vessel C. D. . When the gas is thus collected in the vessel C D, a stream of it may at any time be discharged through the aperture C, and thrown upon the spungy platinum P, when it will produce such an intense heat as to make the platinum red-hot, and thus afford an instantaneous light. In Mr. Garden's lamp, the ring of zinc op, floats upon a piece of cork, so that when the vessel C D is filled with gas, the diluted acid does not touch the zinc, and consequently no more, hydrogen gas is produced ; but the moment any of the gas is let off at c, the pressure of the head of ſluid in Å B overcomes the elasticity of the remaining gas in CD, and the diluted acid is forced up to the zinc, to reproduce the wasted hydrogen. By this ingenious contrivance, the diluted acid is pressed up against the zinc when more hydrogen is wanted, and withdrawn from it when the vessel C D is full. The form given to the lamp by Mr. Adie, of Edinburgh, is shewn in fig. 4, where the different parts are marked by the same letters as in fig. 3. In this construction, a cone of glass, h, formed on the bottom of the vessel A B, is made to hold the ring of zinc, op, which remains permanently in that position. This lamp has the advantage of greater stability, and is less Jiable than the other to be deranged by an accidental cause. Professor Cumming, of Cambridge, who constructed one of these lamps in December 1823, found it necessary to cover up the platina with a test tube, or a cap, after every experiment. With platina foil sºn of an inch in thickness, and kept in a close tube, he produced the same effect; but when the thickness of the foil was gig, it was necessary to raise it previously to a red heat. These lamps, besides their extreme beauty as philoso- phical toys, are of great use in counting-houses, as well as in private houses, in summer. Peck’s Clock LAMP. To those who are in the habit of burn- ing a light during the night, Peck's dial lamp may prove an acceptable companion. A B are two vessels made of tin, about 1% inch diameter, - and the same in depth, communicating at the bot- tom by a small tube. In A burns a floating wick; in B, a float balanced over a cone-like rool, by a small š weight hanging on a piece š of fine silk; the rool should É contain several grooves, SQū ºn d and vary in diameter from a \} § # § # to $ inch. The gradual { º º 57. º - burning of the oil in A, will cause the float B to fall, thereby turning the rool, which being affixed on a wire communicating with the index through the dial, will point out the hour of the night. It is necessary to adjust the index to the true time when the lamp is lighted; and some little attention is requi- site to place the silk in the proper groove on the rool, which acts as a regulator to quicken or retard the burning of the oil.— *:: Mag. 1825. he Safety LAMP, invented by Sir H. Davy, to secure miners bí from the destructive effects of the choke damp and the fire damp; the former con- sists, for the most part, of carbonic acid gas, hovers about the lower parts of the mine, and extinguishes their lights; and the latter, which is simply hydrogen gas, occupies the superior spaces, and involves incalculable mischief, from the combustion produced by its contact with the flame of the miners’ candles. The parts of the lamp are, A, the brass cistern which contains the oil, pierced near the centre with a vertical narrow tube E, nearly filled with a wire which is recurved above, in the level of the burner, to trim the wick, by acting on the lower end of the wire, with the fingers: it is called the safety trimmer. B, the rim in which the wire-gauze cover is fixed, and which is fastened to the cistern by a moveable screw. C, an aperture for supplying oil, fitted with a screw or cork, and which communicates with the bottom of the cistern by a tube; and a central aperture for the wick. D, the burner, or receptacle for the wick, over which is fixed the coil of platinum wire. F, the wire gauze cylinder, which should have not less than 625 apertures to the square inch. G, the second top, # of an inch above the first, surmounted by a brass or copper plate, to which the rings of suspension are fixed. I, I, I, six thick vertical wires, joining the cistern below to the top plate, and serving as protecting and strengthening pillars round the cage. - - - When the wire gauze safety-lamp is lighted, and introduced into an atmosphere gradually mixed with fire-damp, the first effect of the fire-damp is to increase the length and size of the flame. When the inflammable gas forms as much as 1-12th of the volume of the air, the cylinder becomes filled with a feeble blue flame, but the flame of the wick appears burning brightly within the blue flame, and the light of the wick augments till the fire-damp increases to , or 3, when it is lost in the flame of the fire-damp : which in this case fills the cylinder with a pretty strong light. As long as any explosive mixture of gas exists in contact with the lamp, so long it will give light; and when it is extinguished, which happens when the foul air constitutes as much as # of the volume of the atmosphere, the air is no longer proper for respiration; for though animal life will continue where flame is extinguished, yet it is always with suffering. By fixing a coil of platinum wire above the wick, ignition will continue in the metal when the lamp is itself extinguished; and from the ignited wire the wick may be again re-kindled, on going into a less inflammable atmosphere. - Wherever workmen, however, are exposed to such highly explosive mixtures, double gauze lamps should be used; or a lamp in which the circulation of the air is diminished by a tin- plate reſlector placed in the inside ; or a cylinder of glass, reaching as high as the double wire, with an aperture in the inside ; or slips of Muscovy glass may be placed within the lamp ; and, in this way, the quantity of fire-damp consumed, and consequently of heat produced, may be diminished to any extent. Šuch lamps, iikewise, may be more easily cleaned than the simple wire-gauze lamps; for the smoke may be wiped offin an instant from the tin plate or glass. if a blower or strong current of fire-damp is to be approached, double gauze lamps, or lamps in which the circulation of the air is interrupted by slips of metal or glass, should be used; or if the single lamp be employed, it should be put into a common horn or giass lantern, the door of which may be removed or open. Another improvement has recently been made, by which 7 A $50 l, A M L A N DICTIONARY OF MECHANICAL SCIENCE, its utility will be greatly increased. It consists in attaching a convex lens to the lower part of the wire gauze, which enables the miner to direct a strong light upon any particular part of the mine. r -: * - ~ The Rolling LAMP,-Is easily constructed: A B we will suppose is a machine with two moveable, circles, DE, FG, within it, whose common centre of motion and gravity is at K, where their axes of motion cross one another. S If the lamp KC is made pretty heavy, and moveable about its axis HI, and whose centre of gravity below K is fitted within the C. º. - - - - - º * assºs-ºs wº --~~~~~~3 Sº-rºst-ºs- --> • zº-s --> B- - * = --> ---> * = … <- = --- inner cricle, the common centre of gravity of the whole ma- , chine will fall below K, and by reason of the pivots A, B, D, T., H, I, will be always at liberty to descend; hence, though the whole machine be rolled along the table, or moved in any manner, the flame will always be uppermost, and the oil cannot; he spilled. The lamp may be a handsome brass or gilded ball, and the whole effect would be delightful. The Syphon LAMP, an original invention, the description of which appeared some time ago in the London Mechanic's ‘Register. A is a bottle containing oil. B a syphon, one end of which nearly touches the bottom of the bottle ; and which end must be half an inch farther from the parallel line E, than the end D is from the same line. By sucking out the air at D, the oil will follow it copiously; but by drawing up the syphon (which, by a spring, introduced into the neck of the bottle, is made to remain at any height,) till the end C is only a quarter of an inch in the oil, the end D will be empty a quarter of an inch down; into which put a piece of cotton, fitting rather tightly, and after cutting it off flat, at rather more than the eighth of an inch from the tube, push down the syphon, ignite the cotton, XTE : 2. | --sº DO º and this syphon lamp will give a light of a very superior clear- ness; which is to be attributed to the pressing supply of oil at the bottom of the cotton. Moreover, it is a very economical, lamp. The bottle and the piece of tube, which any one can bend into a syphon, cost next to nothing; and the superior; brilliancy of the flame renders it unnecessary that it should be: half the usual size, and consequently a little more than half the usual quantity of oil is consumed. ! LAMPAEDIAS, a term sometimes applied to denote a bearded comet. LAMPBLACK. The finest lamp black is produced by col- lecting the smoke from a lamp with a long wick, which supplies more oil than can be perfectly consumed; or by suffering the flame to play against a metalline cover, which impedes the combustion, not only by conducting off part of the heat, but by obstructing the current of air. . Lampblack, however, is pre- pared in a much cheaper way, for the demands of trade. The dregs which remain after the eliquation of pitch, or else small pieces of fir wood, are burned in furnaces of a peculiar con- struction, the smoke of which is made to pass through a long horizontal ſlue, terminating in a close-boarded chamber. The roof of this chamber is made of coarse cloth, through which the current of air escapes, while the soot remains behind. - LAMPYRIS, in Natural History, FireFly, a genus ofinsects of the order of coleoptera. There are nearly sixty species. The common glow worm is seen during the summer months, on dry banks about woods and pastures, exhibiting, as soon as it is dusk, vivid and phosphoric splendour in form of a round spot, of considerable size. The animal itself, which is the female insect, measures about three-quarters of an inch in length, and is of a dull earthy-brown colour on the upper parts, and beneath more or less tinged with rose-colour, with the two or three last joints on the body of a pale or whitish sulphur colour. It is from these parts that the phosphoric light pro- ceeds. . The male is smaller than the female, and is provided with wings and wing-sheaths: it is not determined whether it be luminous or not. LANA PHILosophica, (philosophical wool,) the snowy flakes of white oxide, which rise and float in the air from the combustion of zinc. - - LANCE, a spear, or offensive weapon, borne by the ancient Cavaliers, in the form of a half pike. The lance consists of three parts; the shaft, the wings, and the dart. It is among the oldest weapons recorded in history. The invention of gun- powder has rendered this instrument of destruction less im- portant than it was in ancient times. LANCET, a chirurgical instrument, sharp-pointed and two- edged, chiefly used to open veins in the operation of phlebotomy, or bleeding; also for laying open abscesses, tumours, &c. LAND, as applied to the earth generally. The constituent parts of the earth are two, the land and water. The parts of the land are continents, islands, peninsulas, isthmuses, pro- montories, capes, coasts, mountains, &c. This land is divided into two great continents, (besides the islands,) viz. the eastern and western continent. . The eastern is subdivided into three parts, viz. Europe, on the north-west; Asia, on the north-east; and Africa (which is joined to Asia by the isthmus of Suez, 60 miles over) on the south. The western continent consists of North and South America, joined by the isthmus of Darien, 60 or 70 miles broad. A Continent is a large portion of land, con- taining several countries or kingdoms, without any entire sepa- ration of its parts by water, as Europe. An Island is a smaller part of land, quite surrounded by water, as Great Britain. A Peninsula is a tract of land every where surrounded by water, except at one narrow neck, by which it joins the neighbouring continent; as the Morea in Greece; and that neck of land which so joins it, is called an Isthmus; as the isthmus of Suez, which joins Africa to Asia; and the isthmus of Darien, which joins North and South America. A Promontory is a hill, or point of land, stretching itself into the sea, the end of which is called a Cape ; as the Cape of Good Hope. A Coast or Shore is that part of a country which borders on the sea-side. Moun- tains, valleys, woods, deserts, plains, &c. need no description. LAND Measuring.—Land is commonly measured by means of the chain and its accompaniments. The Scotch chain is 24 Scotch ells, or 74,138 English feet in length, each link being 8.89656 inches; and the English chain is 22 yards, or 66 feet in length, each link being 7-92 inches. The chain should be accompanied with 1st. Ten small iron arrows, from 12 to 20 inches in length, for sticking into the ground at the end of every chain's length; each arrow having a piece of red cloth fastened to its head, that it may be the more easily observed. 2. Three or four picket staves, from 6 to 10 feet in length, and shod with iron, L. A. N. Iy A N. 551. DICTIONARY OF MECHANIgAL SCIENGE. for sticking into the ground at corners, &c. to direct the sight; each staff having a red or white flag at its top, that it may be seen when placed at a distance. 3. A tape, (such as is used by artificers for measuring their work,) divided into links instead of feet, for measuring offsets, or short distances be- tween the chain-line and the boundary of the field. 4. A cross staff, for setting off the offsets at right angles to the chain line. The cross staff may be constructed thus: Take a thick circular board of well-seasoned hard wood, about 4 inches in diameter, on which draw two straight lines cutting each other at right angles; saw these lines across about half an inch deep, and one-sixteenth of an inch wide. To this board, by means of a socket, fasten a staff shod with iron for sticking into the ground. The dimensions of any piece of ground may be accurately ascertained by these instruments; but for greater ease and despatch, surveyors generally employ some instrument for observing angles. For that purpose, the most proper instru- ment is a theodolite, furnished with two achromatic telescopes, the different adjustments and rack-work motions, parallel plates, compass, level, &c. wº * The plane table also is often of great use in land measuring, as it affords the means of plotting on the spot, the ground as it is measured, and of detecting any errors which may be com- mitted in the work. 4. Problem 1.--To measure a horizontal angle (as BAC, fig. 1, ) by means of the chain.-Rule. Measure any distance, as 100 links from A to B, and there Fig. 1. stick an arrow into the ground; measure the same distance from A to C, and there also place an arrow ; then measure the distance from B to C ; thus will the three sides of the isosceles triangle B A C be known; whence the angle A may be found thus:–Draw the perpendicular Az, and the point a will be in the middle of B C. Then, A B : B & : ; rad : SB A a ; or if B & be reduced to 1000 parts of AB, it will be = the natural sine of B Aa, which being doubled, will give B A C, the angle required. Example.—Let A B or A C be 1 chain, and B C 767 links, what is the angle B A C "767 - 2 = 3835 = Nat. sine of 22° 33', which being doubled is = 45°-6. = B.A. C. Answer. Problem 2–To measure a triangular field, (as ABC, fig. 2.) Rule. Measure the three sides with the chain ; or measure the base A B and the perpendicular DC; or measure any two sides and the included angle; or mea- sure one side, and the two adjacent angles: by adopt- ing any of these methods, sufficient data will be obtained for constructing the figure, and ascertaining its content. - - Fig. 2. Example-What is the area of a triangular field, the three 'sides of which are 806 links, 400 links, and 810 links? Operation. A. R. F. E. 810 O 198 – 2:2966652 1'56563 – 1 2 10 18 Ams. 806 X-202 – 2:3053524 4 400),608 = 2*7839036 *=mmºn *mº -- 2°26252 2)2016 40 1008 = 2.0034605 *=s=== 10°5008 2) 10:3893807 36 156563 = 5-1946903 *mºsºmsºmº 18°0288 Qbservations. The distances are always expressed in links, and not in chains and decimals; the content therefore is found in square links; from the right of which, five figures being cu off for decimals, the rest will be acres, and the decimal being valued, will give the roods, falls, &c. - 2. The method of measuring lines With the chain is as fol. lows:-A picket staff being stuck into the ground in the direc- tion, of the line to be measured, (if there do not appear some mark naturally in that direction,) the assistant takes the end of the chain in one hand, and the ten arrows in the other, and proceeds forward towards the staff, the master measurer, or hindermost chainman, who has the other end of the chain in his hand, standing at the beginning of the line. When the assistant has gone to the end of the chain's length, he is directed in his position by the follower waving his hand to the right or left, till the follower see him exactly in a line with the mark to be measured to ; there both of them stretching the chain straight on the ground, the leader sticks an arrow into the ground at the end of it, as a mark for the follower to come up to, and advances forward another chain, being directed in his position as before; the chain being then stretched, he sticks down an arrow at the end of it, and the follower takes up his arrow. They then advance in the same manner another chain's length; and thus they proceed till all the ten arrows are in the hands of the follower, and the leader without an arrow is arrived at the end of the eleventh chain's length. The ten arrows are then conveyed to the leader, who puts down one of them at the end of his chain, and advances with the chain as before. Thus the arrows are changed from the one to the other at every ten chains length; by this means the length of the line is easily ascertained: thus, if the arrows haye been twice changed, and the follower hold four arrows, and the end of the line cut off 37 links more, the whole length of the line is 2437 links. 3. The method of raising perpendiculars on the ground by means of the cross staff is as follows:—When in measuring along AB (fig. 2.) you come to about D, where you judge thé. perpendicular will stand, plant the cross staff there, and look through one of the slits in the direction of the chain line; then, if on looking through the other slit, it points directly to C, the place of D is right; if not, move the instrument towards B or A, till it do so; thus the point D may be accurately found. 4. The method of measuring horizontal angles by the cross Fig. 3, staff is as follows:—Sup- pose, the obtuse angle, B.A. d, (fig. 3,) were "re- quired. Plant the cross staff at A, and look through one of the slits in the di- rection of B, then look through the other slit, hav- ing previously sent an as- Tº sistant forward a few - chains with a pole to be stuck into the ground at a ; measure A a, then remove the cross staff to a, placing a pole in its stead at A. Look through one of the slits to the pole at A, and then through the other slit to b, and measure a b. Then Aa : a b : : Rad: T, a A b, which being added to 90° gives B.A. d, the angle required. Again, let the acute angle A (fig. 2,) be required. Plant the cross staff at any convenient point in A B as D, and measure AD; look through one of the slits in the direction of A, then look through the other slit, and make a pole be placed at C, where the per- pendicular meets A C ; measure D C. Then AD : D C : : Rad : TA, the angle required. * Problem 3–To measure a four-sided field, (fig. 4.)—Rule. Measure the sides and a diagonal; or measure a diagonal and the two ; perpendiculars; or measure the | sides and one of the angles; or measure the diagonals and the angle of intersection; or measure a diagonal as A C, and the angles C A B, C A D, A C B, A CD ; or measure the distance of a 'point within the field from each of its torners; and the angles at that point subtended by the sides of the field: any of these methods will afford sufficient data for planning the field, and determining its area. & Fig. 4. 552 L. A. N. L A N DICTIONARY OF MECHANICAL SCIENCE. Example.—If A B-598, B C = 439, CD=657, D A = 320, I and A C = 779 links, what is the area of the field A B C D ! Operation 1.—To find the area º of A B C. 2. To find the area of A CD. 439 Y 469 = 2-6711728 779 Q 99 = 1°9956352 ; = 2.4913617 §: = 2^3443923 779 y 129 – 2:1105897 320 y 558 = 2*7466342 2)1816 2) 1756 908 . . . . = 2*9580858 878 .... = 29434945 * 2) 10:2312100 2) 10:0301562 130498 = 5' 1156050 103532 = 5.0160781 Area of A B C = 130498 Area of A C D = 103532 A. R. F Area of ABCD = 2.84030 2 1 iſ Ans. Problem 4.—To measure offsets, (fig. 5.)—Rule. Let A, b, c, d, e,f, B, be a boundary of a field, and A B the chain line, and Fig. 5. the area of the space between them required. In measuring along A B, observe when you are directly opposite to the several bends in the boundary line, as at g, h, i, &c. and mea- sure the perpendicular offsets g b, he, id., &c. with a tape; then calculate the area of each triangle, or trapezoid, into which the space is divided, separately, and their sum will be the whole area. Note. When the boundary is curvilinear, its area may be found by the method of equidistant ordinates, as given in the next problem. Example.-Given A g = 120 links, g b = 62, A h = 220, H c = 40, A i = 280, id = 50, A k = 364, e k = 38, A l = 478, lf = 82, and AB = 576; what is the area of the space A b c def B.A.! A g × 9 b = 120 × 62 = 7440 gº gh x (b g + c h) = 100 × 102 = 10200 hi x (ch + d i) = 60 × 90 – 5400 ik × (di + e h) = 84 × 88 = 7392 h l x (e k + ft ) = 114 × 120 = 13680 1 B x fl = 98 × 82 = 8036 f 2)52148 - A. R. F. E. *26074 - 0 1 1 25. Problem 5.—To find the area of any curvilinear field, by means of equidistant ordinates.—Rule. If a right line A N (fig. 6,) be divided into any even Fig. 6 9. O. number of equal parts, as A C, C. E., E. G., &c. F__#–#—M and if from the pointsof division perpendicular ordinates, as AB, CD, p. E F, &c. be erected; also if A denote the sum of the first and | last ordinates, B the ATETE G. I #, IN sum of the even ordi- - mates, viz. the second, fourth, sixth, &c. C, the sum of all the rest, viz. of the odd ordinates, wanting the first and last, and D the common distance of the ordinates; then will (A + 4B + 2 C) × 4 D = the area. A B O N nearly. Example.—The lengths of five equidistant ordinates of an area are 10, 11, 14, 16, 16, and the length of the whole base 20; what is the area? O Here A = 10 + 16 = 26, B = 11 + 16 = 27, C = 14, and D = 5. Now (A + 4 B + 2C) x + D = (26 + 108 + 28) x 5 = 270. Answer. Note. In this example we have multiplied the sum of the ordinates by 5, and divided the product by 3, because there are in all five ordinates, and the formula compounds them into 3 terms A, B, C. Were there 20 ordinates there would be 12 terms, and we should then have # D as our multiplier. ... In the question before us, 26 + 108 + 28 = 156, which multiplied by 5 = 780; and this divided by 3 is 270, the answer as before. Problem 6–To reduce spaces consisting of several trapezoids, or triangles, to one triangle of the same area, by the parallel ruler. —Rule. At A (fig. 7,) draw an indefinite line a A a ; lay a Fig. 7. parallel ruler from A to c, the 3d point, move the upper part of the ruler to b, and mark where it cuts B & A a, as at 1;—from l * lay the rulerto d, bring its lower edge down to c, and mark where it cuts a A a at 2;- from 2, lay the ruler to e, and move the upper edge to d, and mark where it cuts a A a at 3;-from 3, lay the ruler to f, and bring the lower edge down to e, and mark where it cuts a A a at 4;—from 4, lay the ruler to B, and raise the upper edge to f, and mark where it cuts a A a at 5. From 5 draw the line 5 B ; then will the triangle A B 5 be equal in area to the sum of the two triangles and four trapezoids in the given space. Examples.—1. Reduce the space of which fig. 7 is a sketch, to a triangle of equal area, supposing the measures to be stated in the first exercise to problem 4. 2. Reduce the space of which fig. 8 is a sketch, to a triangle Fig. 8. A # "jºi" º op b Aſ i. #"?”; “it’”; of the same area, the measures being as follows: A i = 68, † b 31, A k 118, h c = 15, A l = 146, l d = 40, A m = 181, m_e = 24, An = 245, m f: 62, A o = 340, o y = 24, Ap = 358, p h = 44, and A B = 418. Problem 6.—To measure any field.—Case 1. When the mea- T sures can be taken within the field.—Rule. Walk over the ground, and consider how it may be best laid out into triangles, trapezoids, &c. and what lines are most suitable to the purpose of accurate measurement, and will occasion least trouble in walking for- ward and backward. TXraw an eye-sketch of the ground in your field book, measure all the necessary lines, and note them down beside the corresponding parts in the sketch ; then calcu- late the content of each part separately in square links, and their sum reduced to acres, &c. will be the content of the field. Case 2. When the ground is covered with wood, water, &c, so that the necessary internal lines cannot be taken.—Rule. Measure | a trapezium surrounding the field, so that the lines measured may make one or more right angles with each other, and mea- sure perpendiculars from those lines to all the angular points tº of the field. Thus a true plan of Fig. 9. the field may be constructed, 944 from which the content may be found, either by deducting the areas of the small parts without § *. the field, from the general con- &S & tent of the outer trapezium, or by º, equalizing the sides of the figure, by the parallel ruler, by prob- lem 5. : Example.—Find the content of © the field, of which ſig. 9 is a sketch, from the measures mark- ed on the sketch. x- L. A N L A N DICTIONARY of MECHANICAL scIENCE. 553 1112-N 339 - 2'5301997 1112~ 355 – 2:5502284 900 $ 551 - 2.741.1516 §: - 2-71850.17 890) 561 - 2.74896.29 878) 589 - 2-77.01.153 2)2902 2)2934 1541 .... = 3'16.16674 1467 . . . . = 3'1664301 2)11-2052755 400532 – 5'6026377 2) 11:1819816 389933 – 5'5909908 878 × 123 = 107994 || Area of 1st triangle = 389933 200 x 132 = 26400 || Area of 2d triangle = 400532 ;400 x 222 = 88800 Area of offsets - 125097 300 × 90 – 27000 f Area of the field = 9:15562 2)250194 Offsets. . . . . . E 125997 9-15562 acres = 9 acres 24 falls. Ans. Remark. Land measurers, for the sake of expedition, often measure in the field such lines only as will enable them to draw a geometrical plot of it; and having plotted it, they divide the plot into triangles, &c. the bases and perpendiculars of which they determine by the scale, and thence compute the content. Problem 7.—To measure several fields lying contiguously to one another.—Rule. When only a few fields are to be measured, the lines may be taken in each field as directed in problem 6; but when many contiguous fields are to be measured and planned, it will be more accurate and expeditious to proceed as follows: Select two convenient stations, as far distant from each other as may be, and from which as much as possible of the ground Fig. 10. * - a misº. - a -4° 4-s- yº ºn." M ..’’L - TJ T to be measured may be seen;–measure with great care the distance between these stations as the principal base, noting ſ Ö7. every hedge or other remarkable object as you pass it, and measuring short perpendicular lines to the bends of such hedges, &c. as are near at hand. From the ends of this base, or from any convenient points in it, measure other lines to some remarkable object situate towards the sides of the ground, noting as before every object as you pass it. These lines, when laid down by intersections, will form one or more large triangles on the ground, on the sides of which other smaller triangles and trapezoids may be formed, till you have sufficient data for plotting and ascertaining the area of the several fields of which the ground consists. - Remark. When a field book is used, it may be divided into three columns. In the middle column may be set down the angular observations, and the distances on the chain line at which any offset or remark is made, and also the whole distance from station to station; in the side columns may be entered the offsets and remarks made on the right and left hand respec- tively, and sketches made of boundaries, &c.; and it will be best to begin at the bottom of the page, and write upwards. Example.—Let the farm, of which fig. 10 is a sketch, be planned, and the content of each field found from the measures stated in the field book in the next page. Problem 8.—To measure and plot hilly ground.—Rule. In order to ascertain the true content of a piece of hilly ground, the whole surface must be measured, as in the case of level ground; but in plotting hilly ground, the area of the base only must be taken. The length of the base line of a hill is found thus:–As radius is to cosine of the angle of acclivity or decli- vity, so is the surface line ascending or descending the hill to the base or plotting line. Example.—The surface line measured up a hill is 500 links, and the angle of acclivity 15° 10'; what is the base or plotting line 2—Answer. Rad : Cos. 15° 10' :: 500 : 482°58 links. Remark. It is a very common practice among land measurers to give for the true content of hilly ground the area of the horizontal plane, instead of the real area of the surface. In defence of which practice it is usually alleged, that “since plants shoot up vertically, the vegetable produce of a swelling eminence can never exceed what would have grown from its levelled base.” But whether this be true to the extent here asserted or not, is a point for the land valuator to determine. It belongs not to the province of the land measurer; his duty obviously is, to ascertain the true area of the surface, and to leave the consideration of the value of the ground, and of its capacity for producing, to those whom it may concern. Remarks on the Field Book.-1. The farm, of which the fol- lowing is a field book, was measured as follows:—The survey was begun at A, poles being placed, in a straight line, at A, B, C, D; the distances between these points were measured; then pits being dug with a spade in the places where the poles at A and B were fixed, (which should always be done at every point where a pole is placed,) these poles were removed from A and B, and placed at E and F, in a straight line with the poles at C and D, and the measurement continued to F. The poles were then removed from C and D, and placed at G and H, in a straight line with the poles at E and F, and the measurement continued to H. Then the poles at E and F were placed at | I and K, and the measurement continued to K, the end of the line. Poles were then placed at L and M, and the distance KM measured. In like manner, poles being placed at M, N, O, P, &c. in a straight line, the distance M A was measured. Poles were then placed at A, T, U, V, and the line AV mea- sured. Poles were then placed at W, X, Y, &c. and the line VF measured. In like manner were the other lines marked in the sketch measured. 2. In planning this survey, the learner should first lay down by the scale and compasses, the large triangle A KM, and then the triangle A F V, drawing the lines with a sharp-pointed black lead pencil;—he should next mark off the several dis- tances A B, A C, A D, &c. writing the mark O where each pole was placed;—he should next measure the offsets to the angles, &c. and where the hedges were crossed;—he should then draw the fences, house, planting, &c.; and when the whole is laid down, it should be carefully inked in, and the black lead lines rubbed out with Indian rubber. 7 B * - **s isº. As a 24 i. 343d it. . ii-, - 3 3: vºid tº... ii. firóñóšA## 6% ºf Ašicăţ ‘scient#. FIELD BOOK. L. A N 5m is and Remarks on wº... l. offsets and Remarks on ; offsets and Remarks on | pist Offsets and Remarks on offse º: Left. . * -- pass. - the Right. : the Leſt. Distance. the ight. H-I- & - * -- - - - Closes at F | 4460 - & - 200 Length - . . . . . . 3450 Z. ; House } 30 Breadth Crosses 3420 edge — * . . . . . 3400 | Y i From S 480 to U Crosses 2000. Hedge & JFrom T 680 to S * , 1900 X & 300. 280 Crosses 1850 | Hedge ... • & - - T F- - 1800 || 60 W, river ; From V 1510 to f . . . . . . 1700 10 River 3 I’ī;om V 1 170 to Cornér of planting . . Crosses 15 Hedge 8. From e 2200 to V . . . . . . . . . . . . . . . . . . . . v 15 to River : - . sºmem-sº- l—H-----—|--|--|-- & From B | 1200 to f Cor. of planting 15 2620 } 5 From B 1000 to Corner of planting | Cor. of planting 15 1535 | 15 : From e 1300 to f Cor. of planting 15 1000 15 & JFrom e 550 to C . . . . . A Road * & From B 2150 to e j Closes at A | 6640 End of the line ; Closes 860 at Y Enters on road 6380 — d ; 780 120 River . 55.25 0 Touches fence 300 100 River 5520 - 200 Corner offence Prom d 5310 270 Fence 870 d ! 5100 270 Fence . . . 600 60 River 5030 120 Boundary fence 340 50 River 4600 180 R Crosses fence JFrom X to d * * 4190. 200 Boundary 1170 (, . Touches 4100 0 Boundary 600 290 River . . . . . 3120 | Q , , , , , 410 | 180 River Crosses hedge ; * #" Boundary ; 300 100 River Crosses hedge 2430 Boundary i F. º º River Boundary 80 2070 O tº. 7°07)2 Boundary 20 1000 N & From C 860 to R. #_ - _|_ M '. : From Q 1730 to C . . - . 3000 M End of the line } From P 1030 to g # - 1600 L ; From b 1590 to P . Turns to left - K - : From O 1240 to b ź. K End of the line : From C 1820 to O . - 6160 110 I to river From N 1440 . Crosses 6090 Road : r #. L #. : § e Crosses 6050 Hedge & From C |ToonT 6030 H - 7"0772 900 to L ' ' - . 4850 G ; From K 1800 to C - Crosses 4820 Hedge } From e 1160 l to b 48% F : From b 830 , to G. - - - - 3720 E } From H 1170 to C - Crosses 3680 Hedge ! From H 1700 to b . . . . . . . . 3630 I) | } Closes at H ITTººnT in on- |Corner of hedge 430 || 3:00 | . . | 8 *** | * ºr Leaves, road 2150 Crosses hedge | ? 540 80 #. Breadth of 20 | 2020 20 Road |: º, º B 2000 ; : | } F;" H 7067" -** -- - - 130 20 Corner of planting 1°0770 Q, to Breadth of 20 ! A | 20 ºn - i From G. 670 to a , Survey begins here. | } Continued. . OF THE Dividing of LAND.—Land measurers are frequently employed to divide a piece of land among sundry tenants or proprietors, in proportion to their respective claims. In order to effect which, the content of the whole must first be accurately , ascertained, and then the division may be made as directed in the following problems. Problem 9.--To cut off a certain portion from a parallelogram by a line parallel to one side.—Rule. Divide the square links in the quantity required to be cut off by the links in the given side, and the quotient will, shew the height on the other sides where the line of division should be drawn. –2. When the portion is to be cut off by a line paralle Example.—What length of a rectangular field, whose breadth is 750 links, will make 2 acres 3 roods 25 falls? Here, 290625 -- 750 = 38.7% links. Answer. Problem 10,--To cut off a certain portion from a triangular field–Rule 1. When the portion is to be cut off by a line drawn from the vertex to the base:–Divide the base in the required proportion, and draw a line from the vertex to the point so found, and it will divide the field as required. For the two triangles thus formed being of the same altitude, are to one another as, their bases, which are in the required proportion. F. Oſlo. L. A N I. A N ... 555 DICTIONARY OF MECHANICAL | SCIENCE of the sides, as A B, fig. 11. From the content of the whole triangle C A B subtract the Tig. 11. quantity to be cut off, viz, a A C B b, and the remainder will be the triangle C a b. Then, because the triangles C A B, C & b are similar, and similar triangles are to one another as the squarés of their like sides, as the whole content C A B is to the remaindef Cab, so is the - o square of the side C A to the square of the side C as the square root of which will be the distance from C to a. Example.—The triangle A B C contains 4 acres, and the length of A C is 895 links; at what distance from C must the Hine of division a b be drawn, in order to cut off 1% acre parallel to AB : 4 : 23 :: 895 : 500640.625 and V 500640.625 = 707:55 links. Answer. Problem 11.--To cut off any quantity from a field, by a line drawn from an assigned point in the side of it.—Rule. Set off from the given point the quantity proposed, as nearly as you can guess, and measure the ground thus set off. . Then divide the difference in square links between the quantity proposed and the quantity set off, by half the length of the guess line, and the quotient will be a perpendicular, to be set off either on one side or the other of the guess line, according as the quantity set off is more or less than the quantity proposed ; to which perpendicular draw a new line from the point assigned, and it will cut off the quantity required. * Examples.—1. From the point a in the field A B C D, fig, 12, it is required to set off 1 acre 3 roods Fig. 12. towards the side B C. A. Draw a b by guess, and measure the # b trapezium a b B C ; suppose you find it to be – 134,400 square links, or too little by 40600 square links, and a b to be – 566 links. Then 40600 —- 283 – 143% links = e a the perpendi- - cular. Thus a a is the line of divi. 4 ision. 11S * D & C 2. The field A B C D E, fig. 13, which contains 5-acres 3 roods 18 falls, is required to be & equallydivided among three Fig. 13. claimants, so that each D may enjoy the benefit of the pool of water at O2 5 a. 3 r. 18 f. E 686250 square links, and 586250- 3 = 195416 square links = each share. Draw EO, and set off the guess line O a ; measure the trapezium A E O at ; suppose you find its area to be ~ 200216 square links, or too much by 4800, and the length of O a to be = 500 links. A Then 4800 - 200 = 24 links the perpendicular from Oa to y. Thus the trapezium O E A y is the first share. * From O set off a guess line to u; measure the trapezium O E D w; suppose you find its area to be = 190916, or too little by 4500, and the length of O w to be = 450 links. Then 4500 -- 225 = 20 links, the perpendicular from w to Oz. Thus the trapezium O E D 2 will be the second share. The figure O y BC 2 is the third share. The methods of using the Plane Table and Theodolite, of Plot- ting, of Copying, Reducing and Enlarging Plans.—1. Before we proceed to exemplify the method of using the plane table, it may be proper to inform the learner, that the paper should be wetted with a sponge before it is laid on the table, that it may , lie the more smoothly; that at every station the table should be placed as nearly horizontal as possible, by moving the legs out or in to the height wanted, and then turned round by the 7& 2 C socket till the north end of the needle points over the fleur de its in the compass box, making the longer side of the table point N and S, and the shorter E and W ; and that before an obser- vation is made, the instrument should be made fast, by turning the screw in the socket. This being premised in order to ex- emplify the use of the plane table, suppose the area and plan of the field, of which fig. 76. is a sketch, were required. Poles being placed at the angle of the field, plant the table at A, observe that it is level, and that the needle settles over the fleur de lis, then screw it fast; assume a convenient part of the paper to represent A, lay the thin end of the index on the point A, look through the sight, and make the pole placed at E and the hair in the sight to coincide, draw the line A E with a black lead pencil, or the point of the compasses, and lay off the mea- sured distance A E from a scale of equal parts; then lift the index, lay its thin edge upon the point A, and take the bearing of B, draw A B, and lay off the measured distance A B, from the same scale as before. Remove the table to B, placing its centre immediately above the hole where the pole stood, slack- en the screw a little, lay the thin edge of the index on B A, and take a back sight to A, hold the index fast, and move the table round, till you see the hair in the sight and the pole at A to co- incide, then screw it fast, turn the index, and lay its thin edge over the point B, and when you see the hair in the sight and the point at C to coincide, draw B C, and lay off the measur- ed distance B C as before. At every station at which a bear- ing is taken, before drawing the line, observe that the index has not moved from the line on which it was laid, and draw the lines as long as possible, for the index can be laid more exact- ly on a long line than on a short one. Remove the table to C, and having taken as before a back sight to B, lay the thin edge of the index on C, and move the index till you see the cross hair and the pole at D to coincide, then draw the line, and lay off as before the measured distance C.D. Remove the table to D, and having taken as before a back sight to C, take the bear- ing of D E ; if it answer, and the line D'E to the measured dis- tance D E, it proves that you have committed no error either in observing the angles or in measuring the distances, for if an error has been committed, the work will not meet. Errors may also be detected thus: leave a pole at any former station; ap- ply the thin edge of the .index to that pole and your present station, and look through the sight to the pole ; then if no error has been commited, the needle will settle over the fleur de lis in the compass. box; if it rest in any other direction, an error has been committed, which should be corrected before you proceed farther. It may be observed, that the same field might also have been measured by either of the following methods. The instrument might have been planted at any of the angles whence the other angles may be seen, as at A, and the bearings of B, C, D, and E from A observed, and also the distances A B, A C, A D, and A E, measured. Or the instrument might have been placed at any point within the field whence all the angles may be seen, as at O, and the bearings of A, B, C, D, and E from O observed, and also the distances O A, O B, O C, O D, and O E measured. By either of which methods it is plain the field may be plotted, and its area ascertained.* - 2. When a survey is to made with a theodolite, before you begin, see that the instrument be properly adjusted, the cross hairs in the telescope exactly in the centre of the tube, and the level right. Then, having placed poles at the angles, &c. and brought the instrument to the place where you intend to begin, plant it there as firmly as you can, and also as level as possible, by moving the legs out and in, till within the limits of the level screws; then having levelled it exactly by means of the four screws between the brass plates fixed to the head of the legs, slacken a little the screw which holds the theodolite fast to the brass-plates, and with both hands turn the instrument round on its axis, till the N end of the needle settles over the fleur delis in the compass box, and set the index to 180° or 360° On the limb, according, as it is divided into twice 180° or into 360; in the latter case the different ends of the needle will alternately agree * A plane table, with index and sights, ball and socket, and three-legged stand, may be purchased from any mathematical instrument-maker; for from four and a half, to five and a half guineas. 556 L. A. N. L. A. N. DIC'TIONARY OF MECHANICAL SCIENCE, with the limb, when the observations are accurate; when the theodolite is placed so that the needle and limb may correspond, the screw that holds the instrument fast to the brass plates must be made tight; and before an observation is made, the screw which holds the telescope and quadrant fast to the limb must be so slackened, that the pinion may turn the teles- cope easily round with the thumb and finger, till the pole pla- ced at the second station is seem to coincide with the cross hairs in the telescope; then the screw is tightened, the bear- ing of the pole at the second station marked on an eye-sketch, and the distance measured. The instrument is then to be planted at the second station, its centre being placed exactly over the hole where the pole stood. Then slacken a little the screw that holds the instrument fast to the legs, and turn the theodolite till you see through the telescope the pole left at the first station; here screw it fast again, and slacken the other screw which holds the telescope and quadrant fast, to the limb ; turn the pinion round to the 3d station, and mark its bearing, and so on. The magnetic needle is used as a test of the accu- racy of the observations; for when no error has been committed, the degrees pointed out by the needle will correspond with those on the limb.” 3. Of the principal method of plotting, or making a plan of an estate, the following brief directions will give the learner some idea:-Suppose the estate measured, by taking a circuit round it with the theodolite, and filling up the interior with the chain. Lay the paper on which the plan is to be drawn very smoothly on a drawing board; draw a pencil line from the top to the bottom, to represent the magnetic meridian ; about the middle of that line make a point, on which lay the centre of the circular protractor, so that the straight edge may coincide with the meridian line ; place a weight above it, to keep it steady in that position, and draw a pencil line round the edge of it. Prick off the angles at the several stations with a plotting pin, marking them 1, 2, 3, &c. and remove the protractor.—Consi- der where the beginning of the work should be placed, so that the whole may come within the compass of the paper, and there make a mark. Lay the fore edge of the parallel-ruler from the central point where the protractor lay, to the mark 1 on the pen- cilled circle. Move the fore edge of the ruler until it touches the point fixed on for the beginning of the plot; from which draw a pencil line in the proper direction; apply a feather- edged scale to this pencil line, so that the division O may be at the beginning of it, and prick off every progressive number where any offsets have been made; then turn the scale across the line, and prick off the offsets on each side of the station line; draw the boundary lines through the offset points, and the first sta- tion will be completed. Proceed thus with each of the other stations in their order, till the work comes to a close at station first. After the principal lines are laid down, proceed to the smaller objects, till you have entered every thing that ought to appear in the plan, as houses, brooks, trees, hills, gates, roads, mills, bridges, &c. When the whole is plotted, draw a line for the true meridian, with a fleur de lis pointing north in a va- cant place, lay down a scale of the proportion you have plotted by, title the map in conspicious characters, and give it a border. 4. A plan may be copied in various ways. One method is by means of a copying glass, being a large square of fine glass set in a frame which can be raised up to any angle, when the lower side of it rests on a table. The paper on which the plan is to be copied, being fixed to the plan by pins at the corners, the plan is then to be laid on the glass; and by means of a strong light placed behind the frame, every line of the plan being distinctly seen through the clean paper, may be accurately traced upon it with a black lead pencil, and afterwards inked in. Another method is as follows: Rub some sheets of cambric paper over with nut-oil, and place the oiled paper for a few days, between sheets of blotting paper. When it is thoroughly dry, lay it upon the plan, with a weight above it, and with a \lack lead pencil go over all the lines, till you have copied the whole upon the oiled paper. Then, having rubbed one side of a sheet of thin paper uniformly over with lead-dust, lay the rubbed side upon the drawing paper, and the oiled plan above * Theodolites sell from five guineas to thirty pounds, and upwards, , according to their construction.) it, and trace the lines of the plan, pressing the tracer so as that the black lead under the lines may be transferred to the clean paper. Thus an accurate outline of the plan may be obtained, which may afterwards be inked in. , Another method is by the instrument called a Pantograph, by means of which a plan may be copied, reduced, or enlarged, very expeditiously, and with the greatest accuracy. This in- strument is not only useful in reducing plans, but it may be employed with equal facility in copying, reducing, or enlarging charts, maps, profiles, landscapes, &c. Another method is by dividing the plan into small squares, by means of equidistant parallel lines, intersecting one another, and then dividing the paper on which the plan is to be copied into the same number of squares, either less or greater than those on the plan, or equal to them, according as you wish the copy to be less, or greater than, or equal to, the original. Then observe in what squares the several parts of the plan are, and draw with a pencil similar parts in the corresponding squares of the copy; when the outline is thus obtained, it may be inked in.—Davidson's Practical Mathematics. LAND, in the sea language, makes part of several compound terms; thus Land-laid, or to lay the land, is just to lose sight of it. Land-locked, is when land lies all round the ship, so that no point of the compass is open to the sea : Land-mark, any mountain, rock, &c. that serves to make the land known at sea. Land is shut in, signifies that another part of land hinders the sight of that the ship came from. Land to, or so far from shore that it can only be just discerned. Land turn, a wind that in almost all hot countries blows at certain times from the shore in the night. To set the land, that is, to see by the compass how it bears. LAND Breeze, a current of air, which, in many parts within the tropics, particularly in the West Indies, regularly sets from the land towards the sea during the night, and this even on op- posite points of the coast. LAND Fall, the first land discovered after a sea voyage ; hence, a good land-fall implies a discovery of the land at or near the place to which the course was directed; and a bad land fall implies the contrary. LAND Loched, is said of a harbour which is environed by land on all sides, so as to exclude the prospect of the sea, unless over some intervening land.—To Make the Land, is to discover it after having been out of sight of it for some time. LAND Mark, any mountain, rock, steeple, or the like, near the sea-side, which serves to direct ships passing by, how to steer, so as to avoid certain dangers, rocks, shoals, whirlpools, &c. LAND Waiter, an officer of the custom-house, whose duty is, upon landing any merchandise, to examine, taste, weigh, mea- sure them, &c. and to take an account thereof. In some ports they also execute the office of a coast-waiter. They are like- wise occasionally styled searchers, and are to attend and join with the patent searcher in the execution of all cockets for the shipping of goods to be exported to foreign parts; and in cases where drawbacks on bounties are to be paid to the merchant on the exportation of any goods, they, as well as the patent searchers, are to certify the shipping thereof on the debentures. LAND Taac, one of the annual taxes raised upon the subject. See TAx. The land tax, in its modern shape, has superseded all the former methods of rating either property, or persons in respect of their property, whether by tenths or fifteenths, sub- sidies on land, hydages, scutages, or talliages; a short expli- cation of which will, however, greatly assist us in understand- ing our ancient laws and history. An act passes annually for the raising in general, £2,037,627. 9s. 10%d by the above- said tax, at 4s. in the pound; whereof there shall be raised in the several counties in England, according to the proportions expressed in the act, £1,989,673. 7s. 10%d. ; and in Scotland, £47,954. 1s. 2d. by an eight months' cess of £5994. 5s. 13 d. per measure, to be raised out of the land rent, and to be paid at four terms, as specified in the act, by two months’ amount each time. LANDEN, John, an eminent English mathematician, was born at Peakirk, near Peterborough, in January, 1719. He became an early proficient in the mathematical sciences, and was a contributor to the Ladies’ Diary in 1744, and continued L. A. N. *L A. N. 557 DICTIONARY OF MECHANICAL SCIENCE. ſ his labours in that useful little performance nearly till his death, suited their present occasions, leaving them to enlarge and in January, 1790. LANDSCAPE. See PAINTING. LANDSMEN, the distinctive appellation of those on board a ship who have never before been at sea, LANGREL, or LANGRAGE, a particular kind of shot, formed of bolts, nails, and other pieces of iron tied together, and form- ing a sort of cylinder, which corresponds with the bore of the cannon from which it is discharged, in order to wound or carry away the masts, or tear the sails and rigging of the adversary. It is seldom used but by privateers or merchantmen. LANGUAGE. Man, of all animals, only is possessed of speech. Mere sound is, indeed, the sign of what is pleasurable or painful, and it is, for that reason, common to most other ani- mals; for in this manner do they signify their feelings to each other. But speech indicates what is expedient or hurtful, and, a natural consequence, of what is just or unjust, it is therefore given to man, by that great Being who endowed him with con- sciousness; for a sense of good and evil is peculiar to man alone. 1. The most intelligent of the brute creation frequently as- tonish us by actions, which can proceed only from powers of intellect similar to our own; the capacity of speech, then, is the criterion of distinction between man and the brute creation. Reason, the capital faculty and characteristic of man, would, without this extensive power of communication, have re- mained in inactivity, its energies unexcited, and its faculties torpid. When the influence of language upon intellect is fully and maturely considered, it will be found that the most brilliant discoveries in philosophy and science are derived from this source. If those, whose genius has dazzled the world with its splendour, had been deprived of the observations and the re- searches of others, they would not have risen above the level of the least cultivated, and most uninformed. Take from man the use of speech, and of visible signs, his intellectual faculties would indeed be circumscribed within very narrow limits. 2. The human voice is air sent out from the lungs, and so agi- tated and modified in its passage through the wind-pipe and larynx, as to be distinctly audible. The windpipe is that tube which, on touching the forepart of our throat externally, we feel hard and uneven ; it conveys air into the lungs for the purpose of respiration and speech. It consists of cartilages, circular before, that they may resist external injury; but flattish on the opposite side, that they may not hurt the aesophagus, or gul- let, which lies close behind, and is the tube which conveys food into the stomach. These cartilages are separated by fleshy membranes; by means of which the windpipe may be short- ened or lengthened, and when necessary, incurvated without inconvenience. The upper part of windpipe is called the larynx; it consists of four or five cartilages, that may be expanded or brought together by the agency of the muscles, which operate all at the same time. - 3. In the middle of the larynx there is a small aperture called the glottis, through which the breath and voice are conveyed, but which when we swallow, is covered by a lid, called the epiglottis; for if any part of our food get into the windpipe by this passage, it occasions coughing, till it is thrown out again. . The best authors have determined, that the human voice is produced by two semicircular mem- branes in the middle of the larynx, which form by their se- paration the aperture termed the glottis. The space between them is not more than the tenth part of an inch in width, through which the breath transmitted from the lungs passes with considerable velocity. It gives, in its passage, a brisk vibratory motion to the membranous lips of the glottis, and thus forms the sound called voice; this is strengthened and mellowed by reverberation from the palate and other cavities in the mouth and nostrils; and as these are better or worse adapted for reverberation, the voice is more or less harmo- Inlous. 4. The origin of language is involved in much obscurity. We are informed by the sacred historian, that the rudiments of Ian- guage were given to man by his Maker; for Adam named all creatures: we must not, however, imagine that this was a per- fect system,--it was but the first step. It is natural to sup- poº,* God taught our first parents only such language as improve it as their necessities required. Supposing a period to exist, when words were uninvented or unknown, men would have had no other method of communicating their feelings to others than by the cries of passion, accompanied by such ges- tures, as were expressive of emotion. These are the only signs which nature teaches, and they are intelligible to all. Were two men, ignorant of each other's language, to meet together, each would endeavour to express himself by gesticulation, by signs, or by short and sudden exclamations; which would be uttered in a strong and passionate manner. These, gramma- rians have denominated interjections, and they were undoubt- edly the first elements of speech. 5. When more enlarged communication became requisite, and names began to be applied to objects, the nature of the object was assimilated as much as possible to the sound of the name. To describe any thing harsh or boisterous, a harsh or boisterous sound was employed; names were never given in a manner purely arbitrary. In the Hebrew, the names of ani- mals given by Adam, bear a striking analogy to the individuals they represent. In the infancy of language, nothing was more natural than to imitate, by the sound of voice, the noise pro- duced by external objects: a number of words may be disco- wered, constructed upon this principle. When one sort of wind is said to whistle, and another to roar; when a serpent is said to hiss ; a fly to buzz, and falling timber to crash; a stream to flow, and hail to rattle; the resemblance of the word to the thing signified, is plainly discernible. The native of Taheite, (usually but improperly written Otaheite,) gives to the gun the appellation of tick-tick-boo, evidently initating the cocking and report of a firelock. The cuckow also derives its name from its note. These, and a host of instances in other languages, prove that words were, originally, imitative. As the multitude of terms, however, increased, and the vast field of learning was filled up, words, by a thousand fanciful and irregular methods of derivation and composition, deviated widely from the primitive character of their roots, and lost all resemblance to the objects which they were intended to repre- sent. Words may be considered as symbols, not as imita- tions; as arbitrary or instituted, not natural, signs of ideas. 6. In the early ages of the world, there is every reason to suppose that the difference of the language in Europe, Asia, and Africa, was no more than a difference of dialects; and that the people of Greece, of Phenicia, and of Egypt, mutually understood each other. The oriental origin of the Latin and Greek is now generally acknowledged'; and to these, the Teu- tonic dialects have an affinity; the Arabic, the Chaldee, the Syriac, and the Ethiopic, still bear the most striking resem- blance to the Hebrew ; in the Welsh, are many words analogous to it: the Celtic, also, has derived much from this and other eastern languages. The Hebrew, then, if we judge from these remarkable facts, from the mode of its derivation, from its radicals, or from the simplicity of its structure, must undoubt- edly be considered as the primitve or parent language. 7. An eminent linguist of the present day, thinks it very likely that the original language was composed of monosyl- lables, that each had a distinct ideal meaning, and only one meaning; as different acceptations of the word would undoubt- edly arise, either from compounding terms, or when there were but few words in the language, using them by a different mode of pronunciation, to express a variety of things. Where this simple, monosyllabic language prevailed, (and it must have prevailed in the first ages of the world,) men would necessarily have simple ideas, and a corresponding simplicity of manners. The Chinese language is exactly such as this; and the Hebrew, if stripped of its vowel points; and its prefixes, suſlixes, and postfixes, separated from their combinations, so that they might stand by themselves, would nearly answer to this character, even in its present state. The same author, speaking of the confusion of tongues, thinks, that God caused the workmen employed in building the Tower of Babel, to articulate the same word differently,–to affix different ideas to the same term, and perhaps, by transposing syllables, and interchang- ing letters, to form new terms and compounds, so that the mind of the speaker was apprehended by the hearer in a con- trary sense to what was intended. 7 C 558 L A. Q L. A N DICTIONARY OF MECHANICAL scIENCE. LANGUOR, among Physicians, signifies great weakness and loss of strength, attended, with a déjection of mind; so that the patients can scarce walk or even stand upright, but are apt to faint away. : LANIARD, or LANNIeRs, a short piece of rope or line, fast- ened to several machines in a ship, and serving to secure them in a particular place, or to manage them more conveniently; such are the laniards of the gun ports, the laniards of the buoy, the laniard of the cat-hook, &c. The principal laniards used in a ship are those employed to extend the shrouds and stays of the mast by their communication with the dead-eyes and hearts, so as to form a sort of mechanical power resembling that of a tackle. The following is the manner in which those la- niards are fixed in the dead-eyes; one end of the laniard is thrust through one of the holes in the upper dead-eye, and then knotted to prevent it from drawing out; the other end is then passed through one of the holes in the lower dead-eye, whence returning upward, it is inserted through the second hole in the upper dead-eye, and next through the second in the lower dead- eye, and finally through the third holes in both dead-eyes. The end of the laniard being then directed upwards from the lowest dead-eye, is stretched as stiff as possible by the application of tackles, and that the several parts of it may slide with more faci- lity through the holes in the dead-eyes, it is-well smeared with hog's lard or tallow, so that the strain is immediately communi- cated to all the turns at once. LANISTER, in Antiquity, is sometimes used to signify an executioner, but more frequently for a master gladiator, who taught the use of arms, and had always people under him ready to exhibit shows of that kind. For this purpose, they either purchased gladiators, or educated children in that art, that had been exposed. LANIUS, the Shrike, in Natural PHistory, a genus of birds of the order picae. There are fifty-six species. The great shrike is about the length of ten inches, and found in France in great numbers, but rare in England. It subsists on insects and small birds, seizing the last by the throat and strangling them, and then fixing them on a thorn, from which it tears them piecemeal and devours them. To decoy them within its reach, it imitates the song of many birds, which approach, delighted by the sounds, and unsuspicious of the danger. It is a favou- rite bird with husbandmen, as it is considered by them a mor- tal enemy to rats, mice, and other species of vermin. It, how- ever, prefers mountainous and secluded situations to the neigh- bourhood of mankind. • The red-backed shrike is much more frequently to be met with in this country than the last species. It is particularly fond of grasshoppers and beetles, which, as indeed various other articles of its food, it will stick upon a thorn. LANTERN, a well known machine, of which there are many used in a ship, such as poop-lanterns, top-lanterns, signal-lan- terms, store-room lanterns, powder-room lanterns, &c. LANTERN, in Architecture, a little dome raised over the roof of a building, to give light, and serve as a crowning to the fabric.—The term lantern is also used for a square cage of carpentry, placed over the ridge of a corridor gallery, between two rows of shops, to illumine them, like that of the Royal Exchange, London. - Darh LANTERN, one with one opening, which may also be closed up when the light is to be entirely hid, or open when . is occasion for the assistance of the light to discover some object. & # Magic LANTERN, an optical machine, whereby little painted images are represented so much magnified, as to be accounted Tºlº the effect of magic by the ignorant. The contrivance is briefly this: A B C D is intended to represent a tin lantern, from whose side there proceeds a square tube bºn k l m c, consisting of two parts; the outermost of which, ºn klm, slides over the other, so as that the whole tube may be lengthened or shortened by that means. In the end of the arm n k l m, is fixed a convex glass, k l ; about de there is a contrivance for admitting and placing an object, de, painted in dilute and transparent colours, on a plane thin glass; which object is there to be placed in- verted. This is usually some ludicrous or frightful represen- tation, the more to divert the spectators. LAPIDARY. The cutting and polishing of gems is the work of the lapidary, and is in general thus performed: The form most proper to be given to any particular gem being determined on, it is cemented to the end of a stick, and the different facets are formed by a mill contrived for the purpose. This mill is a plate of copper, or an alloy of lead and tin, to which an horizontal motion is given by very simple machinery, and the surface of which is charged either with diamond pow- der and oil, or with fine emery and water. A thick peg of wood, called a gauge, pierced with small holes in all directions, is set upright on the lapidary’s bench, close to the mill, and the pro- cess of forming the facets thus takes place. The stone is placed on the surface of the mill, the opposite end of the stick to which it is cemented being inserted in one of the holes of the gauge. In this position it is kept steady by the workman with the right hand, whilst with the other he puts the mill in motion. The skill of the lapidary depends on regulating the velocity of the mill, and pressing with more or less force on the stick, with an almost imperceptible tendency to one or other direction in different stages of the work, examining each facet at very short intervals, in order to give as great precision as possible to its size and form. This part of the business being completed, the cutting mill is taken out, and replaced by one of brass, on which the polishing is performed by means of fine emery, tripoli, and rotton-stone, exactly in the same manner as is practised in the first stage of the process for setting the facets. LAPIDESCENT, any thing which has the faculty of petrify- ing, or turning bodies to a stony nature. The older naturalists speak of lapidescent juices. * LAPIS, in general, is used to denote a stone of any kind. LAPLY SIA, or SEA-HARE, a genus of marine animals belonging to the class of vermes. LAPSANA, Nipplewort, a genus of plants belonging to the syngenesia class, and in the natural method ranking under the 49th order, compositae. - LAPSE, in Ecclesiastical Law, a slip or omission of a patron to present a clerk to a benefice within six months of its being void; in which case, the benefice is said to be in lapse, or lapsed, and the right of presentation devolves to the ordi- nary. t LAPSED LegAcy, is where the legatee dies before the testator, or where a legacy is given upon a future contingency, and the legatee dies before the contingency happens. LAP-sided, the state of a ship which is built in such a man- ner as to have one side heavier than the other, and by conse- quence to retain a constant heel or inclination towards the hea- viest side; unless when she is brought upright by placing a greater quantity of the cargo or ballast on the other side. - LAQUEARIUS, a kind of master wrestler, or champion, among the ancients, who in one hand held a laqueus, i. e. a sort of snare, wherewith to embarrass and entangle his anta- gonist, and in the other a poniard to stab him. LAQUERING, the laying on metals coloured or transparent varnishes, to produce the appearance of a different colour in the metal, or to preserve it from rust. Thus, laquered brass appears gilt; and tin is made yellow. Seed-lac is the chief composition for laquers, but turpentine makes a cheaper laquer. ſº - }. imitate Gilding on Brass, take one ounce of turmeric, add a drachm of saffron, and another of arnotto, and add to these a pint of spirits of wine. Place the bottle in a moderate heat, shake it frequently for several days, and in the end you will procure a fine yellow. Add now three ounces of seed-lac, and when this is dissolved, strain off the mixture: or you may mix. one ounce of turmeric root ground, half a drachm of dragon's L. A. R. L. A. R. DICTIONARY OF MECHANICAL SCIENCE. 559 blood, and a pint of spirits of wine. Saffron is sometimes used to form the body of colour in this laquer, instead of the tur- meric; it makes a warmer but more expensive yellow, and as turmeric has the advantage in forming a much stronger tinge in spirits of wine, it receives the preference. Aloes and gam- boge are also sometimes used in laquers for brass: aloes are not necessary where turmeric or saffron is used; and the gam- boge, though a strong juice in water, affords but a weak tinge in spirits of wine. - A Laquer for Tin, to imitate a Yellow Metal. Take one ounce of turmeric root, of dragon’s blood two drachms, and one pint of spirits of wine; add a sufficient quantity of seed-lac. : A Laquer for Locks, &c. Seed-lac varnish alone, or with a little dragon's blood; or a compound varnish of equal parts of seed-lac and resin, with or without the dragon's blood. A Gold-coloured Laquer for Gilding Leather. The gilt leather used for skreens, room-borders, &c. is leather covered with silver leaf, and laquered with the following composition: Take four pounds and a half of fine white resin, of common resin the same quantity, of gum-sandarach two pounds and a half, and of aloes two pounds; bruise those which are in great pieces, mix them together, put them into an earthen pot over a good charcoal fire, or any fire without flame. Melt all the ingredients, stirring them well with a spatula, that they may be thoroughly mixed, and prevented also from sticking to the bottom of the pot. When they are perfectly melted and mixed, add gra- dually to them seven parts of linseed oil, and stir the whole with the spatula. Make the liquid boil, stirring it all the time, to prevent the sediment from sticking to the bottom of the ves- sel. When the varnish is boiled seven or eight hours, add gradually half an ounce of litharge, or half an ounce of red- lead, and when they are dissolved, pass the varnish through a linen cloth, or flannel bag. The way of knowing when the var- mish is sufficiently boiled, is by taking a little on some instru- ment, and if it draws out and is ropy, and sticks to the fingers, drying on them, it is prepared. LAQUEUS, in Surgery, a kind of ligature, so contrived, that, when stretched by any weight, or the like, it draws up close. Its use is to extend broken or disjointed bones, to keep them in their places while they are set, and to bind the parts close together. LARBOARD, a name given by seamen to the left side of a ship when the spectator's face is turned in the direction of the head. LARBOARD-Tack, is when a ship is close-hauled, with the wind blowing on her larboard side. LARBOARD-Watch, a division of a ship's company on duty while the other is relieved from it. See the article WATCH. LARBOWLINES, a cant term used by the boatswain's mates, implying the larboard watch. LARCENY, or THEFT, by contraction for latrociny, latroci- mium, is distinguished by the law into two sorts: the one called simple larceny, or plain theft, unaccompanied with any other atrocious circumstance; and mixed or compound larceny, which also includes in it the aggravation of a taking from one's house or person. 1. Simple larceny, when it is the stealing of goods above the value of twelvepence, is called grand larceny; when of goods to that value, or under, is petty larceny: offences, which are considerably distinguished in their punishment, but not otherwise. See TH eft. 2. Mixed or compound larceny, is such as has all the properties of the former, but is accom- panied with either one or both of the aggravations, of a taking from one's house or person. LARD, the fat of swine, which differs in its situation from that of almost every other quadruped, as it covers the animal all over, and forms a thick, distinct, and continued layer be- twixt the flesh and the skin, somewhat like the blubber in whales, applicable to various purposes both culinary and medi- cinal ; and particularly to the composition of ointments. The usual mode of preparation is to melt it in a jar placed in a ket- tle of water, and in this state to boil it, and run it into bladders that have been cleaned with great care. The smaller the blad- ders are, the better the lard will keep. The fat which adheres to the parts connected with the intestines differs from com- Imon lard, and is preferably employed for the greasing of car- riage wheels. LARES, among the ancients, derived by Apulius De Deo Socratis, from ...ſ. a kind of domestic genii, or divi- nities, worshipped in houses, and esteemed the guardians and protectors of familiery supposed to reside more immediately in the chimney corner. The lares were distinguished from the penates, as the former were supposed to preside over house- keeping, the servants in families, and domestic affairs; and the latter were the protectors of the masters of families, their wives, and children. Accordingly, the lares were dressed in short succinct habits, to shew their readiness to serve; and they held a sort of cornucopia in their hands, as a signal of hospitality and good housekeeping. According to Ovid, there were generally two of them, who were sometimes represented with a dog at-their feet. The lares are also called penates, and were worshipped under the figures of little marmousets, or images of wax, silver, or earthenware. LARGE, a phrase applied to the wind when it crosses the line of a ship's course in a favourable direction, particularly on the beam or quarter; for instance, if a ship is steering west, the wind in any point of the compass to the eastward of the south or north, may be called large, unless it is directly east, and then it is said to be right aft. SAILING Large, is therefore the act of advancing with a large wind, so as that the sheets are slackened and flowing, and the bowlines entirely disused. This phrase is generally opposed to sailing close-hauled, or with a scant wind, in which situation the sheets and bowlines are extended as much as possible. LARMIER, in Architecture, a flat square member of the cornice below the cinasium, and jets out farthest; being so called from its use, which is to disperse the water, and cause it to fall at a distance from the wall, drop by drop, or as if by tears, the French word larm signifying a tear. LARUS, the Gull, in Natural History, a genus of birds of the order anseres. They inhabit principally the northern cli- mates, subsisting on carrion, and on fishes. Gmelin reckons fifteen species, and Latham nineteen.—L. marinus, is twenty- nine inches in length, and of the weight of five pounds. It is found in various parts of England, and on most of the northern coasts of Europe. It breeds in the most elevated cliffs, laying its eggs on heaps of dung deposited by various birds. It feeds principally on fishes, but sometimes attacks birds. The herring- gull, somewhat less than the former, frequents the same situ- ations, and subsists, like that, chiefly upon fish. In the herring season it is seen watching the nets of the fishermen, and is daring enough frequently to seize its prey from the boats and nets.-The common gull, sixteen inches long, and about a pound in weight, breeds on the rocks and cliffs on the British coasts; and on the banks of the Thames, near its union with the sea, may be seen in immense numbers, picking up the worms and small fishes deposited by the tide. It will also follow the course of the plough over the fields, to pick up the insects and worms which are thrown up by it—The black-cap, or pewit gull, breeds in the fens of Lincolnshire and Cam- bridgeshire, and, after the season of breeding is over, returns to the coasts. The old birds of this speciés are both rank and tough, but the young are eaten by many persons, and were formerly much admired for the table, taken so young as to be unable to fly.—The brown gull weighs about three pounds. It is more frequent in the cold than in the warmer latitudes, and is perhaps the most daring and fierce of all the species. In the Faro islands, lambs are stated to be often torn to pieces by it, and carried to its nest. On the island of Foula, however, it is said to be highly valued on account of its enmity to the eagle, which it attacks, and follows with the most animated hostility. Its feathers are thought by many to equal those of the goose.—The tarrock breeds in Scotland, and is found so . far north as Spitzbergen. It is an attendant on the progress of whales and other large fishes, which drive the smaller inha- bitants of the ocean into creeks and shallows, where the tar- rocks suddenly dart on them, ensuring always an easy and full repast. The tarrock and its eggs are food for the Greenlanders, and of their skins are made caps and garments. t LARVA, in Natural History. The larva state of insects, in general, denotes caterpillars of all kinds. The caterpilhar state is that through which every butterfly must pass before it arrives at its perfection and beauty. - 560 I, A T L A T . DICTIONARY OF MECHANICAL SCIENCE, LASHERS, are properly those ropes only which bind fast the tackles and the gbreechesief ºthès ordnance, when they are haled or made fast within board. - secure any moveable body in a ship, or about her masts, sails, and rigging, is chiefly used for binding up to the ship’s side muskets, butts of waterior, beer, or pieces of timber to make spare top- masts. . . . . . .” . . . . . . . . . . . . - t LASKETS, small lines like hoops, sewed:to the bonnets and drabblers of a ship, to lash or lace the bonnets to the courns, or the drabblers to the bonnets. - LASKING, is much the same with going larger or veering ; that is, going with a quarterly wind. See the article Veer. LASSITUDE, or WeARINess, in Medicine, a morbid sensa- tion, that comes on spontaneously, without any previous motion, exercise, or labour. This is a frequent symptom in acute distempers; it arises either from an increase of bulk, a diminution of proper evacuation, or too great a consumption of | the fluids necessary to maintain the spring of the solids, or from a vitiated secretion of that juice. - - LASTAGE, signifies the ballast or lading of a ship. LATEEN’SAIL, a triangular sail, frequently used by xebecs, polacres, fettees, and other vessels navigated in the Medi- terranean sea. • . : L’ATELIER, De L’IMPRIMEUR, the Printing Press, is due to the innovating spirit of Monsieur Bode, who composed this asterism out of some distinct but unformed stars situated in the . Milky Way, and Eastward of Canis Major's head : Boundaries and Contents: north, by Monoceros, east, by Canis Major; south, by Argo Navis; and west by Monoceros, Argo Navis, and Pyxis Nautica. . . . . . LATERAL EQUATION, is a term used by some old authors for what is now more commonly called a SIMPLE Equation. . LATH, in Building, a long, thin, and narrow slip of wood, nailed to the rafters of a roof or ceiling, in order to sustain the covering. - LATH-BRicks, a particular sort of bricks, made in some parts of England, of twenty-two inches in length and six in breadth, which are used in the place of laths or spars, sup- | ported by pillars in casts, for the drying of malt. This is an excellent contrivance; for besides that they are not liable to fire, as the wooden laths are, they retain the heat vastly better; so that being once heated, a very small quantity of fire will keep them so. LATHE, a very useful engine for the turning of wood, ivory, metals, and other materials. The invention of the lathe is very ancient. Diodorus Siculus says, the first who used it was a grandson of Daedalus, named Talus. Pliny ascribes it to Theodore of Samos, and mentions one Thericles, who rendered himself very famous by his dexterity in managing the lathe. With this instrument the ancients turned all kinds of vases, many whereof they enriched with figures and ornaments in basso relievo. The lathe is composed of two wooden cheeks or sides, parallel to the horizon, having a groove or opening between ; perpendicular to these are two other pieces called puppets, made to slide between the cheeks, and to be fixed down to any point at pleasure. These have two points, between which the piece to be turned is sustained; the piece is turned round, backwards and forwards, by means of a string put round it, and fastened close to the end of a pliable pole, and underneath to a treadle or board moved with the foot. There is also a rest which bears up the tool, and keeps it steady. As it is the use and application of this instrument that makes the greatest part of the art of turning, we shall notice it hereafter under that word; at present we shall give a particular description of Maudsley's Lathe, as well as the manner of applying its various parts to one another. Mawdsley's LATHE, is shewn at large in the plate. A is the great wheel, with four grooves on the rim. " This wheel is worked by a crank B and trundle C, in the common way, by a catgut string, which in going round the wheel passes also round a Smaller wheel D, called the mandrel. This mandrel has on its circumference four grooves, of different diameters, for giving it different velocities, corresponding with the four grooves on the great wheel A. To make the same band suit, when applied to all the different grooves on the mandrel D, the great wheel. A can be raised or lowered by means of the screw a, and another at the end of the axle; and the connect- - - ing rod e can be lengthened or shortened by screwing, the LASHING, which denotes a piece of rºpe used to fasten or | - - hooks at each end of it, further out of it, or more into it: ` The end M of the mandrel D is pointed, and works in a hole in the end of a screw, passing through the standard E, fig. 1; the other end of the bearing F, fig. 2, is conical, and works in a conical socket in the standard F, 1; hence, by tightening up the screw in E, the conical end F may at any time be made to fit its socket: the puppet G has a cylindric hole through its top, to receive the polished pointed rod d, which is moved by the screw e, and fixed by the screw f: the whole puppet is fixed on the triangular prismatic bar H, by a clamp, fig. 8, the ends of which, a b, pass through holes, b, in the bottom of the pup- pet under the bar, and the hole is fixed by the screw c pressing against it: by this means, the puppet can be taken off the bar without first taking off the standard 1, as in the common lathes, and the triangular bar is found to be preferable to the double rectanglar one in common use. - - -- The rest J, in three pieces, is a similar contrivance; see figs, 3, 4, and 5. : Fig. 4, is a piece, the opening a, b, c, in which is laid upon the bar H, fig. 1; the four legs d ddd of fig. 5, are then put up under the bar (into the recesses in fig. 4, which are made to receive them) so that the notches in d ddd may be level with the top of fig. 4, the two beads efin fig. 3, are then slid into the notches in the top of d ddd fig. 4, to keep the whole together; the groove ireceives a corresponding piece on ef, fig. 3, to keep it steady, the whole of fig. 3 has a metallic cover, to keep the chips out of the grooves. h It is plain, that by tightening the screw h in the bottom of fig. 4, the whole will be fixed and prevented from sliding along the bar H, and fig. 3, from sliding in a direction perpendicular to the bar; the piece l, fig. 3, on which the tool is laid, can be raised or lowered at pleasure, and fixed by the screw m. On the end n of the spindle P, figs. 1 and 2, is screwed oc- casionally an universal chuck for holding any kind of work which is to be turned (see fig. 6.). A is the female screw to receive the screw m, fig. 1; near the bottom of the screw A is another screw B B, which is prevented from moving end ways by a col- lar in the middle of it fixed to the screw A : one end of the screw B B is cut right-handed, and the other left-handed; so that by turming the screw one way, the two nuts EF will recede from each other, or by turning it the contrary way, they will advance towards each other; the two nuts EF pass through an opening in C, and project beyond the same, carrying jaws like those of a vice, by which the subject to be turned is held. For turning faces of wheels, hollow work, &c. where great accuracy is wanted, Maudsley has contrived an ingenious appa- ratus which he calls a slide-tool, represented by fig. 7, where E E E is the opening to receive the bar H, fig. 1, and is fixed by the clamp, fig. 8, as before described ; the tool for cutting, &c. is fixed in the two holders b b by their screws; these holders are fastened to a sliding-plate a, which can be moved back- wards and forwards by the screw c, causing the tool to advance or recede; fig. 9, represents the under side (turned upward) of the part A A, in which the screw c is seen fixed at each end, and the nut d, which is attached to the under side of the plate a, working upon it. When it is necessary, as in the turning of the inside of cones, &c. that the tool should not be parallel to the spindle P, the screw e and another similar one behind must be loosened, the tool set at the proper angle, and then be screwed tight again. - To make the piece A A move truly when it is turned round, there is a hole f, fig. 9, to receive a knob g, fig. 14, upon the plate B, which acts as a centre, and keeps it in its place; there are three holes on each side in the plate B, fig. 12, to put the screw e in at different times, thus giving the tool a greater range than the circular openings S.S. will admit. The part EEEE, represented separately and inverted in fig. 10, is of cast iron, and has a screw h working in it similar to fig. 9; the nut of this screw is attached to the bottom of the slide H, fig. 11, at t, which slides in the groove i, figs. 7 and 10; at...one. end of it is a box containing a screw m, hereafter described, and at the other is a frame of brass K.K. Near the same end of the slide is a pin L, projecting above the plate, which is put - - - - - º - - - * 2º/, Z/, 2/ / ^^ - º%zzzzzzzzz. | - ſ º - fººd / M __” – – a ſ " . * *||m|| - *. º - ºf Eiº E_E - Wºº-E === Hºlº Hºº | LP Hºsº In wº s it. º . º| R. ſº i. D =ºff-Hº sº – ſº ºr =nº]|| º N- I, A T f, A T 561. DICTIONARY of MECHANICAL scIENCE. through an opening, J, in fig. 12, to steady it; while the other end C of fig. 12, is put through an opening M in the box D, fig. 11. In the part C is an oblique slit ll to receive a stub which projects from the bottom of the nut n, worked by the screw m, fig. 11; by this arrangement it is obvious that if the screw m is worked, the stub of the nut n, acting against the slide of the slit ll as an inclined plane, will move it backwards or forwards through the opening M ; a metal cover r, fig. 14, is occasionally ut over the opening for the nut n and screw m, to prevent the chips from falling in. Near the four corners of the frame, fig. 12, are four small pro- jections oooo, with inclined sides, that fit into the four openings pp. pp of figs. 13, and 7, these openings are cut out in two brass plates, screwed on at right angles to the plates B B, figs. 7, and i8; the ends q q qq of these plates slide between the edges of the frame K K and the box D, so as to prevent any other mo- tion than a vertical one. When this slide-tool is used, the puppet G is to be removed or pushed back further from F, and the tool is put upon the bar H, fig. 1, and fixed in the place of the rest J, by the clamp fig. 8; the distance from the centre n is adjusted by the screw h, which moves the slide, fig. 11. in the grooves i, figs. 7, and 10, with the whole apparatus upon it; by the screw m, figs. 7, and 11, as before described, the slide, fig. 12, may be moved in a direction perpèndicular to the bar H, fig. 1; and its projections o o acting against the slits pp, figs. 7, and 13, as inclined planes, will raise or lower the plate B as is required. The tool, which has been before fixed in the holders b b, can be set at the proper angle, by loosening the screw e, as pre- viously described: and lastly, the tool with the holders and slider a can be advanced or withdrawn by working the screw e. The nuts of the screws c, and h, fig. 7, are not screwed fast to the sliding plates, but are held by two pins t. fig. 11, which fit into grooves u, fig. 10, in each side of the nut; by these means, the sliding plate can at any time be taken out by only unscrewing one of the brass sides from the groove i, without taking out the screw and nut. To make the grooves always fit their slides, the two pieces of brass y y, fig. 7, composing the sides of the groove, have elliptic holes for their screws v, so as to admit, when the screws are slackened, of being pushed in- wards by the screws w, which work in a lump of metal cast with the part A.A. The larger lathes which this machinist uses in his manufac- tory, instead of being worked by the foot, as represented in fig. 1, are worked by hand; the wheel and fly-wheel which the men turn works by a strap on another wheel fixed to the ceiling, directly over it; on the axis of this wheel is a larger one, which turns another small wheel or pulley, fixed to the ceiling, directly over the mandrel of the lathe; and this last has on its axis a larger one which works the mandrel D, by a band of cat- gut. These latter wheels are fixed in a cast-iron frame, move- able on a joint; and this frame has always a strong tendency to rise up from the action of a heavy weight; the rope from which, after passing over a pulley, is fastened to the frame: this weight not only serves to keep the mandrel-band tight, when applied to any of the grooves therein, but always makes the strap between the two wheels on the ceiling fit. As it is ne- cessary that the workman should be able to stop his lathe, without the men stopping who are turning the great wheel, there are two pulleys or rollers, (on the axis of the wheel over the lathe,) for the strap coming from the other wheel on the ceiling; one of these pulleys, called the dead pulley, is fixed to the axis with which it turns, and the other which slips round it, is called the live pulley; these pulleys are put close to each other, so that by slipping the strap upon the live pulley, it will not turn the axis; but if slipped on the other it will turn with it: this is effected by a horizontal bar, with two upright pins in it, between which the strap passes. This bar is moved in such a direction as will throw the strap upon the live pulley, by means of a strong bell-spring; and in a contrary direction it is moved by a cord fastened to it, which passes over a pulley, and hangs down within reach of the workman's hand; to this cord is fastened a weight, heavy enough to counteract the bell- spring, and bring the strap up to the dead pulley, to turn the lathe; but when the weight is laid upon a little shelf, prepared for the purpose, the spring will act and stop it. . & 58. There is some additional apparatus for cutting the teeth of wheels, in which the face of the mandrel D, fig 1, has seventeen concentric circles upon it, each divided into a different number of equal parts, by small holes. There is a thin stop, ac, fig. 1, which moves round on a screw, fixed in the standard F : this stop made of thin steel is so fixed, that when turned up, and its point inserted to any of the divisions of the mandrel, it has a sufficient spring to keep it there : the wheel to be cut is fasten- ed, by means of a chuck, to the screw m, and after it has been turned, and brought to the proper shape, the rest J is taken away, and the slide-tool substituted: a square bar is then put into the two holders, bb, fig. 7; this bar has two branches for holding the ends of a spindle, near one end of which is a pulley, and, instead of the circular saw commonly used, at the other are four chisels, fixed perpendicularly into the spindle, for cutting out the teeth; the pulley is turned with the intervention of se– veral wheels to augment the velocity by the same great wheel as the lathe, with 7300 revolutions per minute; the mandrel is then fixed by the stop ar, fig. 1, and the cutter advanced towards the wheel by the screw c, fig. 7. When it has cut that tooth, the cutter is withdrawn, and the mandrel turned to another division, and another tooth is cut again as before. At that part of the frame of the cutting spindle where the bar, fixed in the holders of the slide-tool, connects with the two branches, there is a joint, by which the cutting-spindle can be placed in an inclining position, for cutting oblique teeth, like those which work with an endless screw. The great velocity with which this spindle turns, soon generates, by friction and resistance, a degree of heat sufficient to expand it very sensibly ; but this ingenious mechanist has judiciously compensated for it in his construction, by making the spindle so short as to play loosely in its sockets at the commencement of the motion ; but after a few seconds the expansion causes the whole to fit together as it ought to do, and the work of cutting proceeds with accuracy, safety, and despatch. As an improvement on the common lathe, Mr. Williamson, of Union-street, Lambeth, from many years’ experience, has been induced to turn his attention to some mode of decreasing the friction, and lightening the labour. This he has at length accomplished by a simple addition to the machine that we shall immediately describe, first saying a few words on the construction of the common lathe. The diameter of the wheel is about three feet; of the pulley, four or five inches; the line in- troduced under the one and over the other, com- monly touches about $ of the pulley; and, there- fore, to cause any body to revolve, whose diame- ter is the same as that of the pulley, or larger, a very thick line, about three-eighths of an inch diameter, or a line very tight, must be used, which in either case in- creases the friction, and of course materially in- creases the labour. Now, the way in which Williamson works his lathe, so as to decrease the friction and lighten the labour, is by carry- ing the line over a second pulley, working on cen- tres, and so placed as to leave the workman the power of tightening the line with facility, by means of a weight, according to the work he is engaged on. With this little addi- tion, , the workman uses a line only one-eleventh of an inch thick, which, applied according to the above figure, will carry, or cause to revolve, upon a nine-inch pulley, the nave of a waggon 7 D *sº ** sº sº ** smº * sº- &mm : * =3 * nº-ºº: * * * sº * tºº *-*. * -: ºmº * * * * * ºmº * =3 •mº * * * * * * 562 L. A. T. I, A T . BICTIONARY OF MECHANICAL SCIENCE. wheel, sixteen inches diameter, and eighteen inches long, (the dimensions in rough.) We mention this, to shew that it is suited to all sorts of work that can be done by the turner, and, in fact, enables him to do much heavier work than his strength would permit in the ordinary way. . . . Its advantages appear to be:–1. Decrease of friction. 2. That the same line can be employed for all the various speeds that are necessary. 3. That the effect of the various temperatures of the atmosphere upon the line is of mo conse- quence, as, by means of the weight, it can be made to accom- modate itself to the different changes. With catgut, which is generally used, this change of atmosphere, in the ordinary way, is found to occasion not only the frequent destruction of lines, but a great waste of time in repairing them. e e * The turner has generally upon his mandrel various-sized pulleys; yet it is no uncommon thing to find the line too slack upon one pulley, and too tight upon the next, when of neces- sity it must be dragged upon the larger, where it frequently breaks immediately, especially if the atmosphere is becoming more dense. . Upon the same pulley, the line can be used slack for small, articles, and as tight as it may be found necessary for larger articles, by decreasing or increasing the weight, as occasion may require. - . - ... " . Description of the Drawing.—A, the wheel; B, the pulley; C, the additional pulley for the line to revolve on; D, the frame in which the additional pulley C works on centres; E, a joint on which the frame D works, to tighten the string by means of the weight H; F, screw centres for the pulley C; G G, pulleys for communication between the weight H and the frame D ; H, the weight; I, section of the wheel. A ; K, section of the pulley B; L, centres and edge of the additional pulley C.; M, a pin, on which, when the ring at the end of the line N is hung, the lathe is stopped. -..... te Shortly after this account of Mr. Williamson's improvement made its appearance in the Mechanic's Magazine, a corre- spondent in that publication remarked, that this improvement, though extremely valuable, was susceptible of considerable simplification; and at the same time presented the following drawings of a plan, as calculated to prevent the line from chafing, and likewise obviate the necessity of changing the line for heavy work, as in the original plan. . Fig. 1 is the appearance of the lathe endwise; C represents one of two pieces, which are fixed to the back-bed of the lathe; F is a lever, moveable on the centre o, which lever has a piece cut out of the end, to admit the extra pulley D, which Fig, 1. Fig. 2. - D #t R --------> -E:=E---> º-º-º-º-º: * E======= arme=º *-ºs- *=--> **º- rºle *::: *::= -\º ====== <=º: *** * *s - - = -º-º:- ** Nº-º-º: ſº ÆAÉ w*-*. É É 1. := *mºmºmº- -------- == = = # --- := = #= E= == - # :=º É *#A º #:£ºtº-E E :== must, to allow the band to pass without rubbing, be placed so as to stand in winding with the pulley on the mandrel, as shewn by d, fig. 2; the lever F is furnished with hooks, on which the weight G is hung, according to the nature of the work. It would improve the plan, if the grooves in the mandrel-pulley, instead of being angular, were turned rather flat at the bot- tom. Fig. 2 will be readily understood, as the same letters denote the same parts as in fig. 1. A A are beds of the lathe; C, the mandrel-pulley; B, the large wheel. ' - ºrios, is sometimes used for translation or change of place. . . * * LATITUDE, in Geography or Navigation, is the distance of a place from the equator, reckoned on an arch of the meridian, intercepted between its zenith and the equator. - North LATITUDE, is that which falls in the northern hemi- sphere; viz. between the equator and the north pole. South LATITUDE, is that which falls in the southern hemi- sphere, or between the equator and south pole. - . Parallels of LATITUDE, are small circles of the sphere sup- posed parallel to the equator; and are thus called because they shew the latitude of places by their intersection with the meridians, all places falling under the same circle being in the same latitude. The quadrant, or meridian, intercepted be- tween the equator and either pole, is divided into ninety degrees, and numbered both ways from the equator to the poles; and the latitude of any place is equal to the measure of the arch intercepted between the equator and that place, and which is said to be north or south, according as it is situated towards the north or south pole. The latitude of a place, and the elevation of the pole above the horizon of that place, are terms, frequently used indifferently the one for the other, being in fact equal to each other. To comprehend with precision the definitions now laid down, we shall have recourse to a diagram. The circle - - - MO N E repre- sents the hori- zon, in the cen- tre of which, and on the earth, an ob- server A is placed; B C D, B'C'D' are por- tions of circles which the hea- NV 2^ A: M. venly bodies 2^ seem to de- \2T_* scribe round B J& - the celestial - - pole (P), when we fancy they rise in the east and set in the west. Those whose distance from the pole is less than the arc PN, which marks the elevation of this point above the horizon, appear to describe entire circles, such as GK I H. N is the north point of the horizon: M the south; and consequently MN is the meridian line. The semi-circle M ZN, the plane of | which is supposed to be perpendicular to the horizon MEN O, and which passes through the points MN, is the celestial meridian, which divides the arcs B C D, B' C'D', into two equal parts in the points C, C'. The point E is the east point of the horizon, and the point O the west point:—the heavenly bodies seem to move from E to O by transversing the meridian M ZN, which marks the middle of their course. * *. If we conceive the terrestrial globe we inhabit to be insu- lated, our station in the horizon and the axis of the earth being . similar as in the diagram, it is evident that the horizon turning with us during the rotation of the globe, advances successively towards the stars situated in the direction of its motion, which consequently seems to be moving in an opposite direction to approach us. The plane M Z N of the meridian M. N, perpen- dicular, to the horizontal plane EN OM, turns also with this latter, and directs itself successively towards the same stars which are then in the middle of the course which they seem to describe above, the horizon. . When the western edge of the horizon touches a star, it appears to set, and ceases to be visi- ble till the motion of the earth brings the eastern edge of the horizon towards it; because, during this interval, the visual rays which touch the earth pass above the star. This illustra- tion accounts, in the most plain and simple manner, for the L. A. T. L. A U. 563 DICTIONARY of MECHANICAL SCIENCE. daily appearance and disappearance of the celestial bodies, by which circumstance the sun produces the alternation of day and night. All the motions alluded to, in the preceding definitions, are measured by their angles only, without any consideration of their absolute distances. g - The Zenith is indicated by Z, being perpendicularly over the observer's head; and the Nadir is directly opposite. , If we suppose the plane B'C' D' to be perpendicular to the axis of rotation, which passes from P through A, till it meets in the opposite hemisphere a point coinciding with P, this plane B C D* will indicate the equator, all the points of which are at an equal distance from the poles P, P'. It follows from this equality, that, to a spectator placed on the equator, the poles are in the horizon; but as he advances towards either pole, it becomes elevated, while the other is depressed. And the angle P A N, which measures the elevation of the pole above the hori- zon, is equal to that which measures the angular distance of a place from the equator, estimated in the direction of the meri- dian. Also the height at which the equator appears above the horizon, is the complement of the angle Z. A C*; for ZAN, C/A P, being respectively right angles, if we subtract the com: mon angle Z AP, the remainder ZAC’ = PA N. Hence if we suppose Z to be London 51° 31' from the equator C, the elevation of the pole is also 51° 31'. As soon then as the height of the pole above the horizon can be determined for any place, the angular distance of this place from the equator is known, or the number of parts of the meridian intercepted between this place and the horizon. " . - The circumpolar stars, which never set in those places where one of the poles is elevated above the horizon, determine this immediately; for since they appear to describe circles round the celestial pole, they are equally distant from it in every direction, and as they pass twice over the meridian during the diurnal revolution of the earth, namely, once above the pole, and once below it, if we measure their angular elevation at each of these positions, and take the mean of these two results, we shall obtain the elevation of the pole. - . Let A be an observer on the earth, and let G H I K be the circle which a star describes round the point P; then by mea- suring the angle I A N when the star is on the meridian above the pole, and also the angle G A N when the same star is on the meridian below the pole; the angles I A P, G A P being equal, the angle PAN is the mean between I A N and G A N, and is equal, consequently, to half their sum. Moreóver, if we take half the difference I A G of the angles I A N and G A N, measured between the star and horizon, we shall obtain the angle IA P, which will give the angular distance between the observed star and the celestial pole. - Thus, by measuring, for example, at London, during a long winter's night, the two meridian heights of the polar star (a Ursae Minoris, having 88°20'49" declin. N.) we find that (Ann. 1820,) When it passes above the pole its altitude A 53° 10' 11" II, CaSu TéS . . . . . . . . . . . . . tº e º 0 is tº e º is e a e g $ - And when it passes below the pole, it O 7 IIA63.SUl IſèS. . . . . . • * * * * * * * * * tº º e º 'º © tº Q tº e } 49 51. 49' The sum of which is . . . . . . .............. 103°02' 00" And their half.... . . . . . . . . . . . . . . . . . . . . . . 51° 31' 00". Which will be the altitude of the pole above the horizon of London, or the distance of this city from the equator. + If, on the contrary, we subtract 49° 51'49" from 53° 10' 11", we shall find for their difference 3° 18' 22", of which the half 1° 39' 11" will give the distance of the polar star from the pole (in 1820), which we thus find does not exactly occupy this point, but is yet very near to it. The stars enable us to determine another position relative to any place where our former observation may have been made, namely, the longitude of that place: between the passage of the same star over any two meridians, a period of time elapses which is to the whole time of rotation as the angle made by these meridians is to two right angles; so that if the first interval can be measured, to compare it with the second, we may deduce the angle which the two meridians make with each * In referring to this diagram, the reader will understand that a right lieu is supposed to connect Z.A, PA, CA, &c. other. This could be done, if we could indicate by a signal visible at the same time to the places under the two meridians the moment when a star appears on one of the meridians; be-, cause this instant being marked, a well-regulated watch would give the time which elapses between this transit and that of the same star over the other meridian. - - ... • If, for example, two observers, one at Portsmouth, R. N. Academy, and the other at Plymouth Garrison, having agreed to determine on the same day, the transit of the same star over the meridian of the place they inhabit, and that a signal given the moment when the star passes the meridian of Portsmouth Academy, could be visible at Plymouth garrison, about 12 minutes 6 seconds would elapse before the star would pass the meridian of Plymouth; and this interval being nearly the 120th part of the diurnal revolution of the earth, it follows that the plane of the meridian which passes over the Royal Navy Aca- demy at Portsmouth, makes with that of the plane of the meri- dian which passes over the garrison of Plymouth, an angle. which is nearly, the 120th part of four right angles, or the mea- sure of 3°1'23" according to actual observation. If for Ports- mouth and Plymouth' we substitute St. Paul’s, London, and Sherburn Castle, the premises will give us one 360th part of the earth's diurnal revolution, or 4 in time = 1° of the equinoctial. This second position of a place being thus determined, fixes its exact situation; for Sherburn, for instance, being, we shall Say, in the same latitude with London, and 4 later than it, its longi- tude is 1° west. So also Plymouth is 3° 1' 23" west of Ports- mouth.--From Dr. Jamieson's Celesti Al At LAs. - LATITUDE, in Astronomy, as of a star or planet, is its dis- tance from the ecliptic, being an arch of latitude of a circle of latitude, reckoned from the ecliptic towards the poles, either north or south. Hence, the astronomical latitude is quite dif- ferent from the geographical, the former measuring from the ecliptic, and the latter from the equator, so that this latter answers to the declination in astronomy, which measures from the equinoctial. The sun has no latitude, being always in the ecliptic, but all the stars have their several latitudes, and the planets are continually changing their latitudes, sometimes north and sometimes south, crossing the ecliptic from the one side to the other; the points, in which they cross the ecliptic, being called the nodes of the planet, and in these points it is that they can pass over the face of the sun or behind his body, viz, when they come both to this point of the ecliptic at the same time. - Circle of LATITUDE, is a great circle passing through the poles of the ecliptic, and consequently perpendicular to it, like as the meridians are perpendicular to the equator, and pass through its poles. - LATITUDE of the Moon, North ascending, is when she pro- ceeds from the ascending node towards her northern limit or greatest elongation. # , * , LATITUDE, North descending, is when the moon returns from her northern limits towards the descending node.—LA titude, South descending, is when she proceeds from the descending node towards her southern limit.—LAn 11 UDE, South ascending, is when she returns from her southern limit towards her ascending node: and the same is to be understood of the other planets. Heliocentric LATITUde, of a Planet, is its latitude or distance from the ecliptic, such as it would appear from the sun. This, when the planet comes to the same point of its orbit, is always the same, or unchangeable.—Geocentric LATITUDE, of a Planet, is its latitude as seen from the earth. This, though the planet be in the same point of its orbit, is not always the same, but alters according to the position of the earth in respect to the planet. The latitude of a star is altered only by the aberration of light, and the secular variation of latitude. - • Difference of LATITUDE, is an arc of the meridian, or the nearest distance between the parallels of latitude of two places. When the two latitudes are of the same name, either both north or both south, subtract the less latitude from the greater, to give the difference of latitude; but if they are of different names, then their sum will be the difference of latitude. LATTEN, iron plates tinned over, of which tea-canisters are made. See TiNNING. * - - LAUGHTER, an affection peculiar to mankind, occasioned Ö64. L. E. A. L. A U. DICTION ARY OF MECHANICAL SCIENCE. ' by something that tickles the fancy. In laughter, the eye- brows are raised about the middle, and drawn down next to the nose; the eyes are almost shut; the mouth opens and shews the teeth, the corners of the mouth being drawn back and raised up; the cheeks seem puffed up, and almost hide the eyes; the face is usually red; the nostrils are open; and the eye wet. . . . . . . . º LAUNCH, a peculiar kind of boat. The principal superi- ority of the launch to the long boat, consists in being by its con- struction much fitter to undertake the cable, which is a very necessary employment in the harbours of the Levant sea, where the cables of different ships are fastened across each other; and frequently render this exercise extremely necessary. - LAUNCH, is also the movement by which a ship or boat de- scends into the water; hence, to LAUNCH. - To facilitate the operation of launching, and prevent any inter- ruption therein, the ship is supported with two strong platforms laid with a gradual inclination to the water on the opposite sides of her keel, to which they are parallel. Upon the surface of this declivity are placed two corresponding ranges of planks, which compose the base of a frame called, the cradle, whose upper part envelops the ship's bottom, whereto it is securely attached. Thus the lower surface of the cradle conforming ex- actly to that of the frame below, lies flat upon it, lengthways, under the opposite side of the ship's bottom, and as the former is intended to slide downwards upon the latter, carrying the ship along with it, the planes or faces of both are well daubed with soap and tallow. - - The necessary preparations for the launch being made, all the blocks and wedges by which the ship was formerly supported are driven out from under her keel, till her whole weight gra- dually subsides upon her platform, above described, which are accordingly called the Ways. The shores and stanchions by which she is retained upon the stocks till the period arrives for launching, are at length cut away, and the screws applied to move her if necessary. - instant when the shores are cut, and the ship slides downwards along the ways, which are generally prolonged under the sur- face of the water to a sufficient depth to float her as soon as she arrives at the furthest end thereof. - . When a ship is to be launched, the ensign, jack, and pendant are always hoisted, the last being displayed from a shaft erect- ed in the middle of the ship. Ships of the first rate are com- monly constructed in dry docks, and afterwards floated out by throwing open the flood-gates, and suffering the tide to enter, as soon as they are finished. - LAUNCH. Ho, is the order to let go the top-rope after the top- mast is fidded. - - . LAUNDER, in Mineralogy, a name given in Devonshire, and other places, to a long and shallow trough which receives the powdered ore after it comes out of the box or coffer, which is a sort of mortar, in which it is powdered with iron pestles. The powdered ore, which is washed into the launder by the water from the coffer, is always finest nearest the grate, and coarser all the way down. - LAURUS Nobilis. BAY TRee, Leaves and Berries.—In distillation with water, the leaves of bay yield a small quantity of very fragrant essential oil; with rectified spirit, they afford a moderately warm pungent extract. The berries yield a larger quantity of essential oil: they discover likewise a degree of unctuosity in the mouth; give out to the press an almost insi- pid fluid oil; and on being boiled in water, a thicker butyra- ceous one, of a yellowish-green colour, impregnated with the flavour of the berry. An infusion of the leaves is sometimes drunk as tea; and the essential ois of the berries may be given | from one to five or six drops on sugar, or dissolved by means of mucilages, or in spirit of wine. - - LAURUS SASSA FRAs. SASSAFRAs Tree. Bark.-Its medical character was formerly held in great estimation; and its sensible qualities, which are stronger than any of the woods, may have probably contributed to establish the opinion so generally entertained of its utility in many inveterate diseases; for, soon after its introduction into Europe, it was sold at a very high price, and its virtues were extolled in publications pro- fessedly written on the subject. It is now, however, thought to be of very little importance, and seldom employed but in The motion usually begins on the conjunction with other medicines of a more powerful nature. Dr. Cullen found, that a watery infusion of it taken warm and pretty largely, was very effectual in promoting sweat; but he adds, “to what particular purpose this sweating was applica- ble, I have not been able to determine.” In some constitutions, sassafras, by its extreme fragrance, is said to produce head- ache ; to deprive it of this effect, the decoction ought to be employed. - LAURUS, Bay-tree, a genus of the enneandria monogynia class and order of plants. Natural order of holoraceae. There are 32 species. This genus consists of trees or shrubs; leaves mostly entire, in a few nearly opposite, commonly perennial, as in most trees of the torrid zone. L. nobilis, common sweet bay, grows from twenty to thirty feet in height; it has large evergreen leaves, of a firm texture, with an agreeable. smell, and an aromatic bitterish taste; flowers dioecius, or male and female on different trees, in racemes shorter than the leaves, of an herbaceous colour; corollas four-petalled in the male flowers; stamens from eight to twelve; berry superior, of a dark purple colour, almost black; it is a native of the southern parts of Europe and Asia. L. persea, alligator, or avocado pear of the West Indies, is about thirty feet in height; the fruit is the size of one of our biggest pears, enclosing a large seed with two lobes. It is held in great esteem in the West Indies; the pulp is of a pretty firm consistence, and has a deli- cate rich flavour. L. cinnamomum, or cinnamon-tree, is a native of Ceylon. It has a large root, and divides into several branches, covered with a bark, which on the outer side is of a grayish brown, and on the inside has a reddish cast. The body of the tree, which grows to the height of twenty or thirty feet, is covered, as well as its very numerous branches, with a bark, which at first is green and afterwards red. The leaf is longer and narrower than the common bay-tree; and it is three- nerved, the nerves vanishing towards the top. The flowers are small and white, and grow in large bunches at the extre- mity of the branches. The fruit is shaped like an acorn, but is not so large. - - . LAVA, the production of AEtna, Vesuvius, Hecla, and other volcanoes, is of a grayish colour passing to green : it is spotted externally, and occurs porous, carious, or vesicular. Its lustre is vitreous, more or less glistening. It is moderately hard, brittle, easily frangible, and light. It generally attracts strongly the magnetic needle. It is easily fusible into a black compact glass. It frequently encloses other fossils, especially crystals of felspar, augite, hornblende, and leucite. See VolcANoes. LAVENDER LEAves. Lavender has been an officinal plant for a considerable time, though we have no certain accounts of it given by the ancients. Its medical virtue resides in the essential oil, which is supposed to be a gentle corroborant and stimulant, of the aromatic kind; and is recom- mended in nervous debilities, and various affections proceed- ing from a want of energy in the animal functions. - LAYING THE LAND, the state of motion which increases the distance from the coast, so as to make it appear lower and smaller; a circumstance which evidently arises from the inter- vening convexity of the surface of the sea. It is used in con- tradistinction to raising the land, which is produced by the opposite motion of approach towards it. - s To LAY-IN off a Yard, to come from the yard-arms towards the mast, so as to quit it at the rigging. LAYING out on a Yard, is to go out towards the yard-arms. - LAY-MAN, among Painters, a small statue, whose joints are so formed, that it may be put into any attitude, for the pur- pose of adjusting the drapery of figures. - . LAZARETTO, a building, or vessel, fitted up and appointed for the performance of quarantine, in which all persons are confined who are suspected to have come from places infected with the plague. s LAZULITE, in Mineralogy, is of a deep smalt blue: it oc- curs disseminated in fine grains, or masses, of the size of a hazel-nut. h s ! - . LEAD, a white metal of a considerably blue tinge, very soft and flexible, not very tenacious, and consequently incapable of heing drawn into fine wire, though it is easily extended into thin plates under the hammer. Its specific gravity is 1135. It melts at 612 deg. In a strong heat it boils, and emits fumes; L E. A.' L. E. A. DICTIONARY OF MECHANICAL scIENCE. 565 during which time, if exposed to the air; its oxidation proceeds with consdierable rapidity. Lead is brittle at the time of con- gelation. . In this state it may be broken to pieces with a ham- mer, and the crystallization of its internal parts will exhibit an arrangement in parallel lines. Lead is not much altered by expesure to air, or water, though the brightness of its sur- face, when cut or scraped, very soon goes off. It is probable that a thin stratum of oxide is formed on the surface, which defends the rest of the metal from corrosion. Most of the acids attack lead. The sulphuric does not act upon it, unless it be concentrated and boiling. Nitric acid acts strongly on lead. Muriatic acid acts directly on lead by heat, oxidizing it, and dissolving part of its oxide. The acetic acid dissolves lead and its oxides, though probably the access of air may be necessary to the solution of the metal itself in this acid. White lead, or ceruse, is made by rolling leaden plates spirally up, so as to leave the space of about an inch between each coil, and placing them vertically in earthen pots, at the bottom of which is some good vinegar. This, like all the preparations of lead, is a deadly poison. The common sugar of lead is an acetate; and Goulard's extract, made by boiling litharge in vinegar, a subacetate. The power of this salt, as a coagulator of mucus, is superior to the other. If a bit of zinc be suspended by brass or iron wire, or a thread, in a mixture of water and the acetate of lead, the lead will be revived, and form an arbor Saturni. Oils dissolve the oxide of lead, and become thick and consis- tent; in which state they are used as the bases of plasters, :cements for water-works, paints, &c. solves lead in the dry way, and produces a brittle compound, of a deep grey colour and brilliant appearance, which is much less fusible than lead itself. fusible than either metal alone: this is the solder of the plum- bers. Bismuth combines readily with lead, and affords a metal of a fine close grain, but very brittle. A mixture of eight parts bismuth, five lead, and three tin, will melt in a heat which is not sufficient to cause water to boil. All the oxides of lead are easily revived with heat and carbon. Oxygen and lead com- bine together in different proportions. If the nitre of lead be dissolved in a precipitation produced by potash, the preci- pitate, when dried, will become the yellow protoxide. If it be somewhat vitrified, it constitutes litharge ; and combined with carbonic acid, it becomes white lead or ceruse. This protoxide forms the pigment massicot. Massicot exposed for about 48 hours to a great heat, becomes red lead, or minium. Salts of lead have the peroxide for their base. They yield, when placed on charcoal by the blow-pipe, a button of lead. They dissolve in water, and yield a colourless solution of an astringent sweetish taste. Lead, alloyed with an equal weight of tin, ceases to be acted upon by vinegar. Acetate and subacetate of lead have a good effect, as external applications, for inflamed surfaces, burns, scrofulous sores, and as eye washes. Lead taken internally is very injurious: hence the diseases to which painters are liable. Litharge, dissolved in wines, to give them a sweet taste, is very mischievous. Sulphuretted hydrogen will cause it to throw down a black precipitate. LeAD, Black. See Black LEAD. - LEAD, SUGAR of. A salt, denominated from its composition, by modern chemists, acetate of lead, is much used in calico printing and other manufactures. - * . LEAD, Ores of Ores of lead occur in great abundance in almost every part of the world. . They are generally in veins; sometimes in siliceous rocks, sometimes in calcareous rocks. Nearly all the lead in commerce is obtained from galena, which is a compound of sulphur and lead. ... • - LEAD, an instrument for discovering the depth of water; it is composed of a large piece of lead, from seven to eleven pounds weight, and is attached, by means of a strop, to a long line called the lead-line, which is marked at certain distances to ascertain the fathoms. To Heave the LEAD, is to throw it into the sea in a manner calculated to produce the desired effect. Deep-Sea LeAD, a lead of a larger size, being from 25 to 30 pounds weight, and attached to a much longer line than the former, which is called lººpsMAN, the man who heaves the lead. Sulphur readily dis-, Lead unites with most of the metals. Two parts of lead, and one of tin, form an alloy more | only as leases of will. LEADING WIND, a free or fair wind, and is used in contra- distinction to a scant wind. . . . . . . . . . . . . . . . . . . . . LEAGUE, a measure of length, containing more or less geo- metrical paces, according to the different usages and customs of countries. . A league at sea contains three thousand geome- trical paces, or three English miles. The French league some- times contains the same measure, and in some parts of France it consists of three thousand five hundred paces: the mean or common league, consists of two thousand four hundred paces, and the little league of two thousand.—Seventeen Spanish leagues make a degree, or sixty-nine and a half English statute miles. The Dutch and German leagues contain each four geo- graphical miles. The Persian leagues are equal to four Ita- lian miles, pretty near to what Herodotus calls the length of the Persian parasang, which contains thirty stadia, eight of which make a mile. - ; - - LEAK, a chink or breach in the deck, sides, or bottom of a ship, through which the water passes into her hull. When a leak first commences, a vessel is said to have sprung a leak. . LeAKAGE, is the quantity which runs out of a cask through a leak. - - LeAkY, the state of a ship when abounding with leaks; of a cask which suffers the liquor within it to run out. LEASE, a conveyance of lands or ‘tenements generally in consideration of rent or other annual recompense for life, for years, or at will, but always for a shorter term than the lessor has in the premises, otherwise it partakes more of the nature of an assignment. . . . . . . . . . . All leases of lands, except leases not exceeding three years, must be made in writing, and signed by the parties themselves, or their agents duly authorized, otherwise, they will operate If a lease is but for half a year, or a quarter, or less time, the lessee is respected as a tenant for also years. To constitute a good lease, there must be a lessor not restrained from making the lease to the extent for which it is granted; a lessee capable of receiving it; and the interest de- mised must be a demisable interest, and be sufficiently and properly described. If it is for years, it must have a certain commencement and termination; it is to have all the usual ceremonies, as sealing, delivery, &c. and there must be an ac- ceptance of the thing demised. . . . . . . . . . Leases for life must not be made to commence at a future day, and there must be a livery of seisin. They mustnow be stamped as a lease, to be valid; and any form of writing will constitute a lease, provided it contains words of present demise, or actual letting; but if it be only an agreement to let, it conveys no im- mediate title in law, but only an equitable right to have a lease, or to sue at law for not making one. If a lease is made to one for years, and at the same time to another for a longer time, the last lease is not void, but shall take effect after the first expires. A tenant for life can in general only grant a lease to insure during his life; but sometimes a power is annexed to such an estate to grant leases for a specified time, and under particular limitations, all which must be strictly complied with, or the lease is void. An infant may make a lease : but may set it aside when come of age, and the court of chancery is empowered to grant leases for idiots, lunatics, infants, and married women. The rent must be reserved to the executor or the heir of the lessor, according as his estate is real or personal. Lessees are bound to repair, unless the contrary is specified, and although if the house is burnt by accident they are not bound to rebuild yet they must, if the fire be by negligence; and if there is a covenant to pay rent, and a covenant to repair, except in case of fire, yet rent is payable, although the house is not rebuilt by | the landlord. If there is a covenant not to assign, lease, or under-let, without license of the landlord, the tenant cannot even grant an under lease. Upon a lease at will, six months’ notice to quit must generally be given by either party, to ter- minate on the same day in the year when the lease commenced. Leases made by spiritual persons of their church lands, must be conformable to the statute called the Enabling and Disabling statutes. The tenant may, at the trial of an ejectment, insist upon his notice to quit being sufficient, although he made no objection when it was served. – - ' ". . i.EATHER, The Manufacture of The leather tanned in England consists of butts, hides, and skins. “Butts are manti- JE jöö AL E A . I, B. A DICTIONARY OF MEUHANICAL SCIENCE: factured, Šut of theºstrongest skins of oxen. The hides are laid in heaps two days in summer, and six in winter; they are then hung up on poles; in a blose room or smoke-figušé, ex- ‘posed td the heat: of a sºbuldering fire of wet tan. After- wards the hair is scraped off, and they are thrown into a pool of water; and again spread on a woodën beam and carefully scrubbéd. They are now put into pits of strong bark ooze"; again into; a strong solution of vitriolic acid; next they are spread in a pit with ground bark strewed between each, where itfiey. He six weeks, and the decayed bark and liquor being drawa dut of the pit; it will precipitate. Isinglass is used for this purpose, being entirely composed of gelatine. And here -it may be observed, that this! is the mode of ascertaining the "quantity of tanning principle in any vegetable substance, and consequently how far they may be used as a substance for hard oak. The hides being prepared in the usual way, are immersed for some hours in a weak tanning lixivium of two degrees’ streñgth. To obtain this, the latter portions of the infusions are set apart, or else 'some of that which has been (partly exhaustēd by use in tanning. The hides are then to be put into a stronger lixivium, where in a few days they will be :brought to the samé degree of saturation with the liquor in . which they are immersed. The strength of the liquor will thus be.'éonsiderably diminished, and must therefore be renewed. Whéâ the hides are by this means perfectly tanned, they are to be reanoved, and slowly dried in the shade. The length of time necessary to tan Heather completely, according to the old process, is a great inconvenience; and there is no doubt that it may be nuch shortened by following the new method; but , the leather so tanned has not been so durable as that which #as been formed by the slower process. . . . . Sir H. Davy, in treating “on the Constituent Parts of Astrin- gent Vegetables,” thus speaks of tanning:—In considering the relation of the different facts that have been detaited, to the aprocesses of tanning and of leather-making, it will appear suffi- ciently evident, that when skin is tanned in astringentififusions 3that contain, as well as tannin, extractive matters, portions of these matters enter with the tannin, into chemical combi- ination with the skin. In no case is there any reason to believe ...that gallic acid is absorbed in this process; and M. Seguin's ingenious theory, of the agency of this substance, in producing the de-oxygenation of, skin, seems supported by no proofs. ‘Even in the formation of glue from skin, there is no evidence which ought to induce us to suppose that it loses a portion of ioxygen; and the effect appears to be owing merely to the sepa- ration of the gelatine from the small quantity of albumen with which it was combined in the organized form, by the solvent ‘powers of water. The different qualities of leather made with the same kind of skin, seem to depend very much upon the different quantities of extractive matter it contains. The lea- ther obtained by means of infusion of galls, is generally found harder, and more liable to crack, than the leather obtained from the infusion of barks; and in all cases it contains a much larger proportion of tannin, and a smaller proportion of extrao- tive matter. When skin is very slowly tanned in weak solu- :tions of the barks, or caoutchouc, it combines with a consider- able proportion of extractive matter; and in these cases, +hough the increase of weight of the skin is comparatively ‘Small, yet it is rendered perfectly insolubie in water, and is found soft, and at the same time strong. The saturated astrin- gentſinfusions of barks contain much dess extractive matter, in qºroportion to their tannin, than the weak-infusions; and when Skin is quickly tanned in them, common experience shews that: it produces leather less durable than the leather slowly formed. *Besides, in the case of quick tanning by means of infusions of barks, a quantity of vegetable extractive matter is lost to the ‘manufacturer, which might have been made to enter into the Qomposition, of his leather. These observations shew, that there is some foundation, for the vulgar opinion of workmen, goncerning what is technically called the feeding of leather in • the slow method of tanning; and though the processes of the art may in some cases be protracted for an unnecessary length of time, yet, in general, they appear to have arrived, in conse- quence of repeated practical experiments, at a degree of per- £ection which eannot be very far extended by means of any elucidations of theory that have as yet been known... ..., ... " i Currying. The art of currying consists in rendëring tanned skins supple; of uniform density, and impregnating them with oil, so as to render them in a great degree impervious to water, The strong and thick hides are employed for making the soles of boots and shoes, and these are rendered fit for their several purposes by the shoemakers after they are tanned: but such skins as are intended for the upper leathers and quarters of shoes, for the legs of boots, for coach and harness leather, saddles, and other things, must be subject to the process of currying. ... These skins, after coming from the tanners, have fleshy fibres on them. They are well soaked in common water, then taken out, and stretched upon a very even wooden horse; whére with a paring knife all the superfluous flesh is scraped off, and they are again put into a pit or vessel to soak, After the soaking is completed, the currier takes them again out of the water, and having stretched them out, presses them with his féet, or a flat stone fixed in a handle, to make them more supple, and to press out all the filth that the leather may have acquired in tanning, and also the water it has absorbed in soaking. The skins are next to be oiled, "to render them pliant and impervious to wet. After they are half dried, they are laid upon tables, and first the grain side of the leather is rubbed over with a mixture of fish-oil and tallow; then the flesh side is impregnated with a large proportion of oil. After having been hung up a sufficient time to dry, they are taken down and rubbed, pressed, and folded, and then spread out, when they are rolled with considerable pressure upon both sides with a fluted board fastened to the operator's hand by a strap; by this means, and by repeating the rolling, a grain is given to the leather. After the skins are curried, it may be required to colour them. The colours usually given to them are black, white, red, green, yellow, &c. If the skins are to be blacked, the process varies according to the side of the skin to be coloured. , Leather that is to be blacked on the flesh side, which is the case with most of the finer leather intended for shoes and boots, is coloured with a mixture of lamp black, oil, and tallow rubbed into the leather. And what is to be coloured on the grain side is done over with chamber-lie, and then with a solution of sulphate of iron, which turns it black. , Water-proof Leather. To render leather water-proof, the following method is adopted: Take a small pipkin or earthen vessel, and put in it three ounces of spermaceti, to be melted Over a slow fire; then take three-quarters of an ounce of caout- . 'choue, or Indian rubber, cut into thin slices; and the spermaceti will completely dissolve this substance. Add eight ounces of tallow, two Gunees of hog's lard, and four ounces of amber warnish. The boots or shoes must be rendered dry and warm, and this cement well rubbed in, three or four times, with a brush. Morocco Leather is made of the skins of goats, tanned and dyed in a peculiar manner by the Turks. This process, origi- smally invented in the kingdom of Morocco, has given rise to the name of Morocco leather. English Morocco leather, used so largely for coach-linings, pocket-books, and the best kind o. book-binding, is prepared from sheep-skins. - Shagreen is a sort of rough leather, prepared from the skin of the spotted shark. The skin of the fish is first stripped, then extended on a table, and covered with bruised mustard-seed: it is thus exposed to the weather for several days, and after- wards tanned. The best shagreen imported from Constanti- nople, is of a brownish cast, and very hard; but, when im- mersed in water, it becomes 'soft and pliable; and may be dyed to any colour. It is often counterfeited, by preparing Morocco leather in the same manner as the skin of the fish. This fraud may be detected by the surface of the spurious manufacture peeling; or scaling off, while that of the genuine article remains perfectly sound. Shagreen is employed principally in the ‘manufacture of cases for mathematical instruments. : " . Chamois, is a kind of leather, either dressed in oil, oritanned, and much esteemed for its softness...and pliancy. It is pre- | pared from the skin of the chamois, a wild goat, on theimdun- tains of Dauphiny, Savoy, Piedmont, and the Pyrenees. ...Be- sides the softness and warmth of the leather, it has the faculty of bearing soap without hurt. The true chamois leather;is very frequently counterfeited with common goat, kid, and even sheep skin. . . . . . . . . . . . . . . . . . . . . . L. E. E. L E E DICTIONARY OF MECHANICAL SCIENCE. 567 French mode of rendering Leather, Canvass, Linen, &c. Water- proof. The following substances, are first well, ground and mixed together, viz. 1% lb. of the acetăte of lead (sugar of lead,) and 14 lb. of very finely powdered pumice stone; these are then boiled in 100 gallons of the best linseed oil, over a gentle fire, that the oil may not be burned. The liquid should be kept boiling, until it becomes of such a consistence, that after being mixed with a third part of its weight of pipe-clay, it should be of the thickness of molasses. It is then left to clear itself, and afterwards passed through a fine lawn sieve. About 10 pounds of pipe-clay is then to be ground with a solution of the best glue, and so mixed as to be of the consistence of lard; to this mixture is to be added the varnish by degrees, mixing and stirring it well at every addition, with a spatula of wood, until it has become perfectly fluid. The colour is then added, con- sisting of 14 lb. of calcined umber, and 13 lb. of white lead ground in oil. In order to apply it, the linen is stretched over a frame of wood, and the composition spread by means of a broad spatula, about 3 inches wide and 9 inches long. The frame is then inverted, and the composition applied on the other side of the cloth; it is allowed to remain for a week on the frame to dry, and then taken off for use. . The cloth so pre- pared is used for riding cloaks, and as covers for carriages, &c. The same composition is applied to leather and skins, but to produce a glossy brilliant appearance, a varnish is employed, consisting of 5 lb. of the oil warnish, as before mentioned, and an equal weight of clear resin, heated together over a fire until the resin is dissolved; to these are added 2 lbs. of oil of tur- pentine, with which has been ground some colour, to give it the required, tint, and cleared of all impurities by passing This varnish is laid on with a . brush, and when quite hard is rubbed over with pumice stone and water, and afterwards well washed. Two or three coats through a fine lawn sieve. of this varnish are given to it, each coat being well dried before another is laid on, by which is produced a varnish of such bril- liancy as to rival the best japan. The following recipe, although it will not render boots and shoes entirely water-proof, will make them much more imper- vious to wet, more durable and pliable, and prevent their crack- ing:—Take one pint of boiled linseed oil, two ounces of bees- wax, two ounces of spirits of turpentine, and one ounce of Burgundy-pitch, melted carefully over a slow fire. With this composition, rub the soles and upper leathers, when new, with a small piece of sponge, in the sun, or at a distance from the fire; rub them as often as they become dry, until the leather is fully saturated. - Another Methad. Mix equal parts of mutton-fat, bees-wax, and sweet-oil together, in a small gallipot, and heat them over the fire till melted; then, after the mixture has cooled a little, apply it to the shoes plentifully, particularly about the welt and seams, and that will render them entirely water-proof. LEDGE, a long ridge of rocks near the surface of the sea. Iledges, small pieces of timber placed athwart ships, under the decks, in the intervals between the beams. LEE, an epithet to distinguish that half of the horizon to which the wind is directed from the other part-whence it arises, which latter is accordingly called, to windward. This expres- sion is chiefly used when the wind crosses the line of a ship’s course : so that all on one side of her is called, to windward; and all on the opposite side, to leeward ; and hence, . Under the Lee, implies farther from that part of the horizon from whence the wind blows, as, Under the lee of the land, i. e. at a short-distance from the shore which lies in the direction oil the wind. This phrase indicates the situation of a vessel anchored or sailing near the weather shore, where there is always smoother water than at a great distance from it. To lay a ship by the lee, or to come up by the lee, is to bring her so that all her sails lie flat against her masts and shrouds, and that the wind may come right upon her broadside. * Lee Boards, strong frames of plank affixed to the sides o flat-bottomed vessels, such as river barges, &c. which draw but little water; these, by being let down into the water when the vesselis close-hauled, prevent her:from fallingsleeward. , Lee Fangs, are ropes reeved into the cringles of a yacht or hoy’s sails. The Lee Gage, implies further from the point whence the wind blows than another vessel. Take care of the Lee intended for it to act on. Hatch, is a word of command to the man at the helm, to take care that the ship do not go to the leeward of her course. Lee Lurches, the sudden and violent rolls which a ship often takes to leeward in a high sea, particularly when a large wave strikes her on the weather side. • . * * + . A LEE Shore; a ship is said to be on a lee-shore, when she is near the land, with the wind blowing right upon it. LEE Side, all that part of a ship or boat which lies between the mast and the side farthest from the direction of the wind ; or that half of a ship which is pressed down towards the water by the effort of the sails, as separated from the other half by a line drawn through the middle of her length; that part of the ship which lies to the windward of this line is accordingly called the weather side. Thus, if a ship sail southward with the wind at east, then is her starboard or right side the lee- side; and the larboard or left, the weather-side. LEE Tide, is a tide running in the same direction that the wind blows, and is directly contrary to a tide under the lee, which implies a stream in an opposite direction to the wind. To LEEWARD, denotes towards that part of the horizon which lies under the lee, or whither the wind blows. LEEwARD Ship, is one that is not fast by the wind, or which does not sail so near the wind, nor make so good way, as she should ; or which is much to leeward of her course, when sailing close-hauled. Lee Way, or Leeward Way, is the lateral movement of a ship to the leeward of her course, or the angle which the line of her way makes with her keel when she is close-hauled. This movement is produced by the mutual effort of the wind and sea upon her side, forcing her to leeward of the line upon which she appears to sail; and in this situation her course is neces- sarily a compound of the two motions by which she is impelled. All ships are apt to make some lee-way; so that in casting up the log-book, something must be allowed for lee-way. But the lee-way made by different ships, under the same circumstances, will be different; and even the same ship, with different lading, and having more or less sail on board, will make more or less lee-way. The ordinary rules of allowing for it, as given by Mr. John Buckler to Mr. William Jones, who first published them about the year 1702, are these:—1. When a ship is close-hauled, has all her sails set, the water smooth, and a moderate gale of wind, she is then supposed to make little or no lee-way. 2. Allow one point when it blows so fresh that the small sails are taken in. 3. Allow two points, when the topsail must be close reefed. 4. Allow two points and a half when one topsail must be handed. 5. Allow three points and a half when both topsails are to be taken in. 6. Allow four points when the fore-course is handed. 7. Allow five points when trying under the main sail only. 8. Allow six points when both main and fore courses are taken in. 9. Allow seven points when the ship tries a-hull, or all sails are handed. When the wind has blown hard in either quarter, and shifts aeross the meridian into the next quarter, the lee-way will be : lessened. But in all these cases respect must be had to the roughness of the sea with the trim of the ship ; and hence the mariner will be able to correct his course. p LEECHES, Water Snails. To apply leeches effectually, the -skin should be soft, and if lotions have been used, the skin must ibe cleanly washed. and the leeches will bite very readily when they are fresh and hungry. The best mode of applying them is to let the leech crawl on a dry piece of linen for a little time ; -or better, if it have been kept in a vessel without water for some time beforehand, then to take it in a bit of soft linen between the thumb and finger, and when it projects its pointed mouth between the folds of the linen, to direct it to the spot In this way the leech will generally fasten at the first touch, and it will at all events fasten more readily, since it is prevented from covering the skin with slime, | and thus sheathing it from its own bite and that of other | leeches. The most skilful appliers of leeches use this method, and they gain celebrity by thus throwing them on the part, as some of them express it. - Another-way is, to put the leeches into a wine glass or pill- box, and then to invert the glass or box on the proper part. This method, does not answer when the leeches are not lively, for they will fix on the sides of the vessel, so as not to be again 568 L. F. N. L E. O. DICTIONARY OF MECHANI UAL SCIENCE. made to touch the skin. This difficulty may generally be obvi- ated by putting more leeches into the vessel or vessels than are wished to be applied, and removing them when the proper number have adhered. ... * . * In cases of difficulty, it is often advantageous to cover the part with cream or milk; or better, to touch the head of the leech with a drop of vinegar; or to make small incisions in the skin (of the operator perhaps, if the patient be a sleeping child) by means of a lancet: or, if one leech have adhered, to take it off again, and use the blood to entice others to do likewise. Mr. Thomson says, in the London Dispensatory, that a leech may certainly be made to bite on any assigned spot, by putting it into a quill which is open at both ends, and after placing the end containing the leech's head on the part, stopping up the other end by means of the finger. This information is valuable, at least if the plan prove generally successful, in cases where leeches are required close to an important part, as near the eye or on the gums, &c.; but it is to be feared that the quill would be as likely to ſail as the common leech-glass, both being used on the same principle; and the latter being confessedly an ineffective instrument. The pain of biting generally ceases in a short time after the leech has adhered; but if the patient be so placed as that the leech hangs as it were from the point of adhesion, the pain is in some individuals increased, and continues till the leech falls off. Leeches should not remain on the part for more than ten or fifteen minutes; if they do not then fall off, it will be found that they have been sluggish, and are not full, and the same thing will be shewn by the want of that vermicular motion on the neck of the leech, which is so perceptible when it draws vigorously. In these cases it may often be made more active by touching its head with vinegar. . As it sometimes happens that leeches, when indolent, will thus remain on the part for hours, it is better to remove them when they are disposed to suck. This may be done by the application of a very little salt to their heads, and as the after bleeding is gene- rally more advantageous than the drawing of the leech itself, very little loss is sustained by removing them before they are filled with blood.* . The Treatment of Leeches after their Removal from the Skin.— Great waste is occasioned by the unskilfulness in attending to leeches after they fall off. By proper care they may be made to act again and again; for, when it is considered that blood is the natural food of the leech, it must follow, that some fault in our treatment causes their death, and not their having made a hearty meal on food that is natural to them. It may happen, indeed, that the blood in certain states of disease acts as a poison, and destroys them ; many persons having stated that they fall off dead, in some cases, before any application is made to them: but this is at least problematical, and perhaps unlike- ly. The common practice of covering them with salt is almost always destructive; and, even by sprinkling a small quantity on their bodies, if death do not follow, it generally happens that the leech is blistered by the salt, and made incapable of acting again for a considerable time. Squeezing out the blood is bet- ter than the application of salt in any form; but the best mode is to touch them with vinegar, which, if sparingly applied, will make them vomit, so that they may be re-applied again imme- diately, even to the third or fourth time, or, by returning them into clean water, be ready for another occasion. When leeches are treated in this way, and especially if they be allowed to keep, perhaps, a fourth part of the blood which they have swal- lowed, they are not only capable of acting repeatedly, but, in skilful hands, may be made to grow to an immense size. Under one gentleman's care, a set of leeches were in this way preserved for a great length of time, and at last they grew to the length of nearly eight inches. It was want of care that destroyed them, even after all this. These leeches were not once emptied of their blood, and yet they were often used again at an interval of only a few days. We understand it is the practice of some surgeons, when leeches have been scarce, and it has been considered requisite to take a large quantity of * According to one gentleman's experiments, the largest leech is not more than a drachm heavier when full, than before application. If so, small ones cannot draw away more than half a tea-spoonful of blood. . . blood from a patient, to cut off the tail of the leech, when it has nearly filled itself; the creature keeps on sucking to fill itself, and appears to be unconscious of its being employed merely as a funnel or a spout. - * . . - : Leeches, the borders or edges of a sail, which are either sloping or perpendicular; those of the square-sails, i.e. the sails whose tops and bottoms are parallel to the deck, or at right angles with the mast, are denominated from the ship’s side, as the starboard-leech of the main-sail, the lee-leech of the fore-topsail; but the sails which are fixed obliquely on the masts have their leeches named from their situation with regard to the ship's length, as the fore-leech of the mizzen, the after- leech of the jib, &c. : 4 . . . . . Leech Lines, ropes fastened to the middle of the leeches of the mainsail and foresail, and communicating with blocks under the opposite sides of the top, whence they pass downwards to the deck, serving to truss those sails up to the yards. Harbour Leech Lines, ropes made fast at the middle of the topsail yards, then passing round the leeches of the topsails, and through blocks upon the topsail-tye, serving to truss the sails very close up to the yard, previous to their being furled in a body. Leech Rope, a name given to that part of the bolt-rope to which the border or edge of a sail is sewed. In all sails whose opposite leeches are of the same length, it is terminated above by the earing, and below by the clue. . LEET, a little court held within a manor. LEGION, in Roman antiquity, a body of foot, which consisted of ten cohorts or battalions, each cohort consisting of six cen- turies, commanded by a centurion, and when full, a century was 100 men, but the numbers were often incomplete, particularly during a campaign. - * * . . - LEGISLATOR, a lawgiver, or a person who establishes the policy and laws of a state. Such was Moses, among the Jews; Lycurgus, among the Lacedaemonians, &c. ‘. - g LEMMA, in Mathematics, denotes a previous proposition, laid down in order to clear the way for some following demon- stration, and prefixed either to theorems, in order to render their demonstration less perplexed and intricate, or to pro- blems, to make their solution more easy and short. Thus, to prove a pyramid one-third of a prism or parallelopiped of the same base and height with it, the demonstration of which in the ordinary way is difficult and troublesome, this lemma may be premised, which is proved in the rules of progression, viz. that the sum of a series of square numbers in arithmetical pro- gression, beginning from 0, as 1, 4, 9, 16, 25, 36, &c. is always subtriple of the sum of as many terms, each equal to the great- est; or, is always one-third of the greatest term multiplied by the number of terms. * . & * . * LEMONS, SALT of, used to remove ink-stains from linen, is the native salt of sorrel, the super-oxalate of potash. The effect is produced by the oxalic acid dissolving with facility the oxide of iron in the ink, on the combination of which with the tannin and gallic acid, the colour depends; while, at the same time, it can be used without any risk of injury to the cloth, on which it has no effect. - - LEMURES, in Antiquity, spirits or hobgoblins; restless ghosts of departed persons, who return to terrify and torment the living. These are the same with larvae, which the ancients imagined to wander round the world, to frighten good people and plague the bad. . . For which reason, they had at Rome lumeria, or feasts, instituted to appease the manes of the de- funct. See LAREs. LENGTHENING, the operation of cutting a ship down across the middle, and adding a certain portion to her length. This is performed by sawing her planks asunder in different parts of her length, on each side of the midship frame, to pre- vent her from being weakened too much in one place. The two ends are then drawn apart to a limited distance, which must be equal to the proposed addition of length. An inter- mediate piece of timber is next added to the keel, upon which a sufficient number of timbers are erected to fill up the vacancy produced by the separation. The two parts of the keelson are afterwards united by an additional piece, which is scored down upon the floor timbers; and as many beams as may be necessary are fixed across the ship in the interval. Finally, the | planks of the side are prolonged so as to unite with each other, F., E. O. L E 'I' IDICTIONARY OF MECHANICAL SCIENCE. 569 and those of the ceiling refitted in the same manner, by which the whole process is completed. - - LENS, a piece of glass or other transparent substance, having its two surfaces so formed that the rays of light in pass- ing through it have their direction changed, and made to con- verge or diverge from their original parallelism, or to become parallel after converging or diverging. Lenses receive particu- iar denominations according to their form; as convex, concave, plano convex, plano concave, lenses, and meniscuses. Conver LeNs, is one which is thickest in the middle. If only one side is convex and the other plane, it is called a plano con- vez lens, such is A F, in the following figure; but if it be con- vex on both sides, it is called a convero conver, or double convex: lens, as B G. Concave LENs, is that which is thin- nest in the middle ; but it is also divided into plano concave and concavo concave, as in the former case; such are two lenses C H., D I. And when the lens is concave on one side and convex on the other, it is called a meniscus, as E K, in the above figure. In every lens the right line perpendicular to the two surfaces is called the aa is of the lens; the points where the axis cuts the surface, are called the vertices of the lens; also the middle point between them is called the centre, and the distance be- tween them the diameter. Some confine the term lenses to such as do not exceed half an inch diameter, those that exceed this being termed lenticular glasses. Lenses are either blown or ground. Blown Lenses, are small globules of glass melted in the flame of a lamp by a blow-pipe, or otherwise. Ground Lenses, are such as are ground to the required form by means of machinery for this purpose. The LENs Grinding Machine is of varied form and construc- tion. This figure re- presents one of these machines, so contrived as to turn a sphere at one and the same time on two axes, cutting each other at right an- E. e - E gles, and producing the ºff # segment of a true B.º. ſº- 2 º' ~ * i º N |||||||||}=|º |H|| * . |E|# º- sphere merely by i. ing round the wheels # in. any care or *. | of the workman. is Aft <=2 a globe covered with Zº É E. º on which are |====== fixed the pieces ofglass || to be ground; this globe is fastened to the axis, and turns with the wheel B. C is the brass cup that polishes the glass. This is fastened to the axis, and turns with the wheel D. The motion of the cup C, there- fore, is at right angles to the motion of the globe A ; whence it follows demonstrably, that the pieces of glass ground by this double motion must be formed into the segments of spheres. LENT, a solemn time of fasting in the Christian church, observed as a time of humiliation before Easter, the great festival of our Saviour's resurrection. LEO MINort, the Little Lion, it has been said, owes its place in the heavens to the fable of Hercules killing the Nemaean lion. This is erroneous, for Leo Minor was composed out of the stella informes of the ancients. In the Egyptian calendar we find the sign Leo to contain the figures of two lions, and the head of a third. The Little Lion is a paratantellon to Leo of the zodiac. Boundaries and Contents.—North by Ursa Major, east by Coma Berenices, south by Leo, and west by Lynx. This constellation contains 53 stars, viz. one of the 3d magnitude, six of the fourth, eleven of the 5th, &c. and the upper part of the animal’s head does not set to London. The position of Leo Minor is easily ascertained, for it is composed as it were of three knots of stars, one at the head and fore feet, a second on the body, and a third at the tail; and the central group, deter- 59. - -: - - - tº:- - mined by a line drawn from Regulus to the Pointers, enables us to fix on the two others to the east and west. - LEQ, the Lion &, is the fifth sign in the order of the zodiac, and the second of the summer signs. According to the fixed zodiac and the astronomical year, the Sun enters Leo on the 23d of July; but reckoning agreeably to the precession of the equinoxes and the moveable zodiac of the sidereal year, the Sun enters this sign on the 8th of August. The Earth is at this pe- riod in Aquarius, and the Sun, as seen from the Earth, ap- pears in Leo. For, in whatever part of the ecliptic we appre- hend the Sun to be, the Earth is 180° removed from that point. As the Earth goes round the Sun, the North Pole keeps con- stantly towards one part of the heavens; it now approaches nearer its orbit than in the preceding sign, and the days and nights are consequently coming nearer to an equality. Boundaries and Contents of Leo.—This sign is bounded on the north by Leo Minor, cast by Virgo, south by Sextans, and west by Cancer; it contains 95 stars, viz. two of the 1st magnitude, two of the 2d, six of the 3d, thirteen of the 4th, &c. The chief star is Regulus, situated on the Ecliptic, and some- times called Cor Leonis, “the Lion's heart.” In the tail of the Lion we find Denebola, also a star of the first magnitude. The declination of Regulus is 12° 56' 26" north, and its right ascension 149° 25' 29". Regulus rises in the E. N. E. part of the horizon, as does also Denebola, but about 49 more to the N. and 1 hour 30 minutes after Regulus. Regulus rises and culminates, to the inhabitants of London, for the first of every ºth, agreeably to the following Table: Merid. Alt. 51° 25' MONTH. RISEs. CULM. MONTH. | RISES. CUI.M. - ho. mi. ho. mi. ho. mi. ho. mi. Jan. 10 15 A. | 3 10 M. July 3 12 M. 3 19 A Feb. 6 0 A. | 1 0 MI. Aug. 6 0 M. 1 14 A Mar. 4 10 A. | 10 9 A. Sept. 4 0 M. 11 15 M April 2 15 A. | 9 16 A. Oct. 2 15 M. 9 27 M. May 12 20 A. | 7 25 A. Nov. 12 22 M. 7 30 M June 10 8 M. 5 23 A. Dec. 10 22 M 5 27 M The sign Leo is chiefly situated north of the Ecliptic, passing over the northern parts of the torrid zone. And in the heavens the position of Regulus and Denebola may be thus found. LEPAS, the Acorn, a genus of shell-fish, belonging to the order of vermes testacea. - LEPIDIUM, Ditt ANDER, or PEPPERwort, a genus of plants belonging to the tetradynamia class, and in the natural method ranking under the 39th order, siliquosae. * - LEPIDIOPTERA, in Zöology, an order of insects, with four wings, which are covered with imbricated scales. LEPROSY, a foul cutaneous disease, appearing in dry, white, thin, scurfy scabs, either on the whole body, or only some parts of it, and usually attended with a violent itching and other pains. The leprosy is of various kinds, but Jews were particularly subject to that called Elephantiasis. Hence the Jewish law excluded lepers from communion with mankind, banishing them into the country or uninhabited places, without excepting even kings. When a leper was cleansed, he came to the city gate, and was there examined by the priests; after this he took two live birds to the temple, and fastened one of them to a wisp of cedar and hissop, tied together with a scarlet ribbon; the second bird was killed by the leper, and the blood of it received into a vessel of water; with this water the priest sprinkled the leper, dipping the wisp and the live bird into it: this done, the live bird was let go; and the leper hav- ing undergone this ceremony, was again admitted into society, and to the use of things sacred. See Levit. xiii. 46, 47, and xiv. 1, 2, &c. o LERMITE (Oiseau), a constellation formed some years ago by M. Monnier, under the southern scale of the Celestial Balance. Dr. Jamieson, on his Celestial Atlas, has transformed L'Ermite Oiseau into the sage-looking Noctua, a bird, which, considering the frequency it is met with on all Egyptian monu- ments, it appears strange our astronomers have not long ere this transferred among the celestials. . .* . LETHARGY, (a word of Greek derivation,) in Medicine, is a disease consisting of a profound drowsiness or sleepiness, from which the patient can scarcely be awaked; or, if awaked, 7 F 570 L E V L E V DICTIONARY OF MECHANICAL SCIENCE. he remains, stupid, without sense or memory, and presently sinks again into his former sleep. . . . . ..., LETTER of Attorney, in Law, is a writing by which one person authorizes another to do some lawful act in his stead; as, to give seisure of lands, to receive debts, sue a third per- son, &c. The nature of this instrument is, to transfer to the person to whom it is given, the whole power of the maker, to enable him to accomplish the act intended to be performed. ..It is either general or special ; and sometimes it is made revocable, which is when a bare authority is only given, and ..sometimes it is irrevocable, as where debts, &c. are assigned from, one person to another. It is generally held, that the power granted to the attorney must be strictly pursued; and that where it is made to three persons, two cannot execute it. In most cases, the power given by a letter of attorney ter- minates upon the death of the person who gave it. No letter of attorney made by, a seaman, &c. in any ship of war, or having letter, of warfare, or by their executors, &c. in order to em- ..power any person, to receive any share of prizes or bounty- money, shall be valid, unless the same be made revocable, and for the use of such seaman, and be signed and executed before, and attested by, the captain and one other of the sign- ſing officers of the ship, or the mayor or chief magistrate of some corporation. , - ... LETTER of MART, a commission granted by the lords of the admiralty, or by the vice-admiral of any distant province, to the commander of a merchant ship, or privateer, to cruise against and make prizes of the enemy's ships and vessels, either at sea, or in their harbours. The ship so commissioned is also called a Letter of Mart or Marque. - LETTUCE, WILD. Dr. Collin, at Vienna, first brought the wild lettuce into medical repute; and its character has lately induced" the College of Physicians at Edinburgh to insert it in the cata- logue of the Materia Medica. More than 24 cases of dropsy are said by Collin to have been successfully treated, by employ- ing an extract prepared from the pressed juice of this plant, which is stated not only to be powerfully diuretic, but, by attenuating the viscid humours, to promote all the secretions, and to, remove visceral obstructions. In the more simple cases, proceeding from debility, the extract, in doses of eighteen to thirty grains a day, proved sufficient to accomplish a cure ; but when the disease was inveterate, and accompanied with visce- ral obstructions, the quantity of extract was increased to three drachms; nor did larger doses, though they excited nausea, ever produce any other bad effect; and the patients continued so strong under the use of this remedy, that it was seldom mecessary to employ any tonic medicines. Strong-scented wild lettuce ranks, however, among the stupefying poisons; but it is to be hoped, that its disagreeable scent and bitter nauseous taste will operate as a preventive to its being used for food. LEUCIPPUS, an ancient Greek philosopher, who flourished about 420 years before Christ. . . LEUWENHOEK, ANTHoNY, a celebrated Dutch philosopher, was born at Delft in 1632, and acquired a great reputation throughout all Europe, by his experiments and discoveries in Natural History, by means of the microscope. He particularly excelled in making glasses for microscopes and spectacles; and he was a member of most of the literary societies of Eu- rope, to whom he sent many memoirs. Those in the Phil. Trans. and in the Paris Memoirs, extend through many vo- lumes; the former were extracted, and published at Leyden, in 1722. He died in 1723, at ninety-one years of age. LEVEL, an instrument employed in ascertaining a horizon- tal line, of which there are various sorts; as, The Air Level, shews the exact level by means of a bubble of air enclosed with some fluid in a glass tube of an indeterminate length and thickness, and having its two ends hermetically sealed. When the bubble fixes itself at a mark in the middle of the tube, the case in which it is fixed is then level. When it is not level, the bubble will rise to one end. This glass tube may be set in another of brass, having an aperture in the mid- dle, where the bubble may be observed. The liquor with which the tube is filled is oil of tartar, or aqua secunda; those not being liable to freeze as common water, nor to rarefaction and condensation as spirit of wine is. - The Plumb LHvel, shews the horizontal line by means of another line perpendicular to that described by a plummet at pendulum. This instrument consists of two legs, joined or right angles; of these legs, that which carries the thread and plummet is about a foot and a half long; the thread is hung towards the top of the branch. The middle of the branch where the thread passes is hollow, so that it may hang free every where; but towards the bottom, where there is a little blade of silver, whereon is drawn a line perpendicular to the telescope, the said cavity is covered by two pieces of brass, making a kind of case, lest the wind should agitate the thread ; for which reason the silver blade is covered with a glass to the end, to be seen when the thread and plummet play upon the perpendi- cular. The telescope fastened to the other branch of the in- strument, is about two feet long; having a hair placed horizon- tally across the focus of the object-glass, which determines the point of the level, The telescope must be fitted at right angles to the perpendicular. It has a ball and socket, by which it is fastened to the foot. * - * The Water Level, shews the horizontal line by means of a surface of water or other fluid ; founded on this principle, that water always places itself horizontally. The most simple kind, made of a long wooden trough, equally filled with water, shews its surface on the line of level. This is the ancient chorobates. The water-level is also made with two cups fitted to the two ends of a straight pipe, an inch in diameter, and four feet long. The water communicates from one cup to the other; and this pipe being moveable on its stand by a ball and socket, when the two cups shew equally full of water, their two surfaces mark the line of level. This instrument, instead of cups, may also be made with two short cylinders of glass, three or four inches long, fastened to each extremity of the pipe with wax or mastic. The pipe, filled with coloured water, shews itself through the cylinders, by means of which the line of level is determined ; the height of the water, with respect to the centre of the earth, being always the same in both cylinders. This level, though very simple, is yet very commodious for levelling Small distances. - - Where works of moderate extent are carried on, and where the perfect level of each stratum of materials is not an object of importance, the common brick- layer’s level, having a plumb sus- pended from the top, and received in an opening at the junction of the perpendicular with the horizontal piece, will answer well enough. The principle on which this acts is, that as all weights have a tendency to gravitate towards the centre of - the earth, so, the plumb-line being a true perpendicular, any line cutting that at right angles must be a horizontal line at the point of intersection. All this is but an approximation ; we may call these perpendiculars, or what we will, they are in fact radii of a sphere. - But the most complete level that has ever yet been invented, is the spirit level, of which the following is a representation. º ºg : , º, º ºsmºs-ºs-sº E * : "… : - º º > -ºf- --------- ºriº * , º R | $/ éº º 39 wº $##!": JN *ºlºr L E V L E V 571 DICTIONARY OF MECHANICAL SCIENCE. The level q r is surmounted by a telescope O MI, and the whole fixed on a stand resembling that of the improved theodolite, the adjustment of the instrument being effected by means of the screws shewn in the figure. The telescope is a chromatic, about 18 inches long, for viewing remote objects. O I are the Y supporters in which it rests. The spirit level shews when the instrument is properly adjusted. The supporters are fixed in the plate KIK. The screws C, Q, G, H, H, E, and F, are severally used for adjusting the instrument, which is supported by three legs A, B, D. The usual height of the instrument is abous 53 feet; but as an hour's practice will give more informa- tion than pages of description, and as the telescope answers the same purpose, we shall refer the reader to that article. LEVELLING, the finding a line parallel to the horizon at one or more stations, to determine the height or depth of one place with respect to another, for laying out grounds even, re- gulating descents, draining morasses, conducting water, &c. Two or more places are on a true level when they are cqually distant from the centre of the earth. Also one place is higher than another, or out of level with it, when it is farther from the centre of the earth; and a line equally distant from that centre in all its points, is called the line of true level. Hence, because the earth is round, n B R H that line must be a curve, and Gºs A A' make a part of the earth's circum- / > / ference, or at least be parallel to # / 5& it, or concentrical with it; as the ; # / * & line B C F G, which has all its points equally distant from A, the centre of the earth, considering it as a perfect globe. & But the line of sight B D E, &c. given by the operations of levels, A. is a tangent, or a right line perpendicular to the semi-diameter of the earth at the point of contact B, rising always higher above the true line of level, the farther the distance is, is called the apparent line of level. Thus, C D is the height of the appa- rent level, above the true level, at the distance B C or B D ; also E F is the excess of height at F, and G H at G., &c. The difference, it is evident, is always equal to the excess of the secant of the arch of distance above the radius of the earth. The common methods of levelling are sufficient for laying pavements of walks, or for conveying water to small distances, &c.; but in more extensive operations, as in levelling the bot- toms of canals, which are to convey water to the distance of in any miles, and such like, the difference between the true and the apparent level must be taken into the account. Now the diſſerence C D between the true and apparent level at any distance B C or BD, may be found thus: by a well- known property of the circle (2 A C + C D); B D : : B D : C D ; or because the diameter of the earth is so great with respect to the line CD, at all distances to which an operation of levelling commonly extends, that 2 A C may be safely taken for 2 A C +C D in that proportion without any sensible error, it will be . 2 2 2 A C : B D :: B D : CD, which therefore is - *P. or tº: - - - 2 AC 2 A C nearly ; that is, the diſſerence between the true and apparent level is equal to the square of the distance between the places, divided by the diameter of the earth; and consequently it is always proportional to the square of the distance. Now the diameter of the 'earth being nearly 7958 miles, if we 2 first take B C = 1 mile, then the excess becomes aſks of 2 A C a mile, which is 7.962 inches, or almost eight inches, for the height of the apparent above the true level at the distance of one mile. Hence, proportioning the excesses in altitude ac- cording to the squares of the distances, the ſollowing table is obtained, shewing the height of the apparent above the true level for every 100 yards of distance on the one hand, and for every mile on the other. . By the following table of reductions, we can now level to almost any distance at one operation, whereas the ancients, being unacquainted with the correction answering to any dis- tance, could only level from one twenty yards to another, when they had occasion to continue the work to a considerable extent. Distance, or | Differ. of Level, Distance, Differ. of Level, B. C. or C. D. or B C. or C. D. Yards. Inches. Miles. Teet. Inches. 100 0.026. . 3. () 0} 200 0.103 # 0 2 300 0.23 l # 0 4% 400 0°411 1 O 8 500 0.643 2 ... 2 .. 8 600 0.925 3 . 6 0 700 1°260 4 10 7 800 1 *646 5 16 7 900 2:08.1 6 23 11 T 000 2.570 7 32 6 1100 3° 110 8 42 6 1200 3.701 9 53 9 1300 4'344 1() 66 4 T.400 5'038 l 1 . 80 3 1500 5'784 12 95 7 1600 6'58() 13 112 2 1700 7'425 14 130 I This table answers several useful purposes. Thus, 1st, to find the height of the apparent level above the true, at any dis- tance. If the given distance is in the table, the correction of level is found on the same line with it: thus at the distance of 1000 yards, the correction is 2:57, or two inches and a half nearly ; and at the distance of 10 miles it is 66 feet 4 inches. But if the exact distance is not found in the table, then multi- ply the square of the distance in yards by 2:57, and then divide by 1,000,000, or cut off six places on the right for decimals, the rest are inches: or multiply the square of the distance in miles by 66 feet 4 inches, and divide by 100, 2dly. To find the extent of the visible horizon, or how far an observer can see from any given height, on a horizontal plane, as at sea, &c. Suppose the eye of the observer, on the top of a ship's mast at sea, is the height of 130 feet above the water, he will then see about 14 miles all around. Or from the top of a cliff by the sea-side, the height of which is 66 feet, a person may see to the distance of near 10 miles on the surface of the sea. Also when the top of a hill, or the light in a light-house, or such like, whose height is 130 feet, first comes into the view of an eye on board a ship, the table shews that the distance of the ship from it is 14 miles, if the eye is at the surface of the water; but if the height of the eye in the ship is 80 feet, then the distance will be increased by near 11 miles, making in all about 25 miles in distance. 3dly. Suppose a spring on one side of a hill, and a house on an opposite hill, with a valley between them, that the spring seen from the house appears by a levelling instrument on a level with the foundation of the house, which suppose is at a mile distance from it; then is the spring eight inches above the true level of a house; and this difference would be barely sufficient for the water to be brought in pipes from the spring to the house, the pipes being laid all the way in the ground. 4thly. If the height or distance exceed the limits of the table, then, first, if the distance be given, divide it by 2, or by 3, or by 4, &c. till the quotient come within the distances in the table; then take out the height answering to the quotient, and multi- ply it by the square of the divisor, that is, by 4, or 9, or 16, &c. for the height required. Thus, if the top of a hill is just seen at the distance of 40 miles, then 40 divided by 4 gives 10, to which in the table answer 664 feet, which being multiplied by 16, the square of 4, gives 10613 feet for the height of the hill. But when the height is given, divide it by one of these square num- bers, 4, 9, 16, 25, &c. till the quotient come within the limits of the table, and multiply the quotient by the square root of the divisor; that is, by 2, or 3, or 4, or 5, &c. for the distance sought: so when the top of the peak of Teneriffe, said to be about 3 miles, or 15,840 feet high, just comes into view at sea, divide 15,840 by 225, or the square of 15, and the quotient is 70 nearly; to which in the table answers by proportion nearly 10% miles; then multiplying 10% by 15, gives 154 miles and 4 for the distance of the hill. 572 L E V L I B DICTIONARY OF MECHANICAL SCIENGE. What has been stated above, has been said without any re- gard to the effect of refraction in elevating the apparent places of objects. But as the operation of refraction incurvating the rays of light proceeding from objects near the horizon is consi- derable, it can by no means be neglected, when the difference between the true and apparent level is estimated at consider- able distances. It is now ascertained, that for horizontal re- fractions the radius of curvature of the curve of refraction is about seven times the radius of the earth; in consequence of which, the distance at which an object can be seen by refrac- tion, is to the distance at which it could be seen without refrac- tion, nearly as 14 to 13; the refraction augmenting the distance at which an object can be seen by about a thirteenth of itself. By reason of this refraction, too, it happens, that it is neces- sary to diminish by } of itself the height of the apparcnt above the true level, as given in the preceding table of reductions. Thus, at 1000 yards, the true difference of level, when the allow- ance is made for the effect of refraction, will be 2.570 — 367 E 2-203 inches. At two miles it would be 32 — 4} = 27# inches; and so on. - Levelli NG, is either simple or compound; the former is when the level points are determined from one station, whether the level be fixed at one of the points or between them ; and the latter, or compound levelling, is nothing more than a repe- tition of several such simple operations. - Levelli NG Staves, instruments used in levelling, serving to carry the marks to be observed, and at the same time to mea- sure the height of those marks from the ground. They usually consist of two mahogany staves, ten feet long, in two parts that slide upon one another to about 5% feet, for the greater convenience of carriage. They are divided into 1000 equal parts, and numbered at every tenth division, by 10, 20, 30, &c. to 1000; and on one side the feet and inches are also some- times marked. A vane slides up and down upon each set of these staves, which by brass springs will stand at any part. These vanes are about ten inches long and four inches broad; the breadth is first divided into three equal parts, the two ex- tremes are painted white, the middle space divided again into three equal parts, which are less; the middle one of them is also painted white, and the two other parts black; and thus they are suited to all the common distances. These vanes have each a brass wire across a small square hole in the cen- tre, which serve to point out the height correctly, by coinciding with the horizontal wire of the telescope of the level. An excellent levelling staff is now made, by suspending a pole on a pair of pivots or axles, in a limb of brass, swinging itself on axles; these two pairs of axles are at right angles, and the pole stands always perpendicular. The limb of brass is fixed in the top of a stool, with three or four legs, about 18 inches from the ground. - LEVER, THe, treated as one of the mechanical powers, will fall under our notice in Mechanics, where the theory of the various kinds of levers, whether straight or bent, is laid down. Our present object is to describe a combination of the lever with the axis in peritrochio, by means of which the reciprocating motion of the lever is made useful in giving a continued rectili- near motion to a heavy body, without changing the situation of the fulcrum of the lever. This contrivance is generally called in England the universal lever. FG H is a straight lever, whose centre of motion is G.; on its extremity F, hang two bars FD, F E, the former of which has a hook to catch into the teeth of the wheel A CD, and the latter has its end slightly bent, so as to slide over the outer parts of those teeth. The axle A has a cord wound about it, to the lower end of which is . illik attached the weight W. Jº ſº Now suppose the end H of º the lever raised from H by I, while the from F to B; the bar FE will then push the point Eof the wheel from E to C, while the hook D slides over an equal space on the other side of the wheel. After this, on the end H of the E *-es- | iſſiſſil; | lever being brought down again by I to H, the end F ascends through BF, and the hook D raises up the left hand side of the wheel through a space equal to EC. Thus the reciprocating mo- tion of the lever is made to communicate a continued rotatory motion to the wheel, and consequently to raise the weight W suspended from its axle by the cord. Here the advantage gained, neglecting friction and the stiffness of the cord, will be in the ratio compounded of the ratio of H G to GF, and the ratio of the radius of the wheel to that of the axle. Thus if H G were ten times GF, and the radius of the wheel ten times that of the axle, the power would then be to the weight raised nearly as 1 to 100. - This machine has been advantageously applied in drawing heavy loads along a plane nearly horizontal : in that case, the cord has been carried from A in nearly an horizontal direction, passed round a pulley p, attached to the load w or its carriage, and its end fixed to a post as at a, or perhaps to the frame of the wheel and axle. The pulley, it is obvious, almost doubles the advantage of the power; and since the force to be over- come, when once the system is put in motion, is not equivalent to the whole load w, but merely to the friction, and the rigidity of the rope, a very great weight may be moved in this manner by a comparatively small power. If the lever have another arm to the left of G (as it appears in the figure) equal to G. H., a man may then work at each end, either by pressing upon it or by pulling downwards with a cord; and thus the labourers will alternately relieve each other. Sometimes a heart-whee! has been combined with this universal lever: but it is not, we think, a combination to be recommended in practice. If the centre of motion G were vertically above the centre of the wheel, and if another bar and hook similar and equal in length to F D hung from the point f. f G being equal to GF; these two hooks would then catch alternately into the teeth on the rising side of the wheel, and thus produce the continued rotatory motion; but this construction has a practical disad- vantage; for when both bars work on the same side of the wheel, they will be in great danger of catching together, and impeding each other's motions. Universal levers have long been introduced into saw mills, for the purpose of drawing along the logs to be sawn. See SAw Mill, also PIPE BoreR. LEVIGATION, in Pharmacy and Chemistry, the reducing hard and ponderous bodies to an impalpable powder, by grinding them on a porphyry or in a mill. LEVITY, in Philosophy, the opposite to gravity, or that sup- posed quality of certain bodies which gives them a power of ascent; being thus opposed to gravity, by which they have al. ways a tendeney to descend. The ancients supposed several different bodies to be possessed of levity, but the error has long since been detected, and the principle itself excluded from every system of philosophy. LEX, LAw. See LAw. The Roman laws were of two kinds: 1st. Such as were made by their kings. 2d. The laws of the twelve tables, brought by the Decemviri from Athens, &c. And 3d. Such as were proposed by the superior magistrates in the times of the republic. º LEXICON, the same with Dictionary. The word is chiefly used in speaking of Greek dictionaries. - LEYDEN PHIAL, in Electricity, is a glass phial or jar, coat- ed both within and without with tin-foil, or some other con- ducting substance, which may be charged, and employed in a variety of useful and entertaining experiments. Or even flat glass, or any other shape, so coated and used, has also received the same denomination. Also, a vacuum produced in such a jar, &c. has been named the Leyden vacuum. LIBELLUS FAMOSUS. A contumely or reproach, pub- lished to the defamation of the government, of a magistrate, or of a private person. It is also defined a malicious defamation, expressed in printing or writing, or by signs, pictures, &c. tending either to blacken the memory of one who is dead, or the reputation of one who is alive, and thereby exposing him to public hatred, contempt, and ridicule. Libels, says Blackstone, taken in their largest and most extensive sense, signify any writings, pictures, or the like, of an immoral or illegal tendency. This species of defamation is usually termed written scandal and thereby receives an aggravation, in that it is presumed to have been entered upon with coolness and deliberation; and L J B L I C DICTIONARY OF MECHANICAL SCIENCE. 573 to continue longer, and propagate wider and further, than any other scandal. - LIBRA, the Balance re. This is the seventh sign in the order of the Ecliptic, and the first of the southern and autumnal signs. The sun enters it on the 23d of September, reckoning according to the fixed and intellectual zodiac; but, agreeably to the moveable and visible zodiac, and the recession of the signs, it is the 27th of October when the place of the sun cor- responds with the commencement of Libra. By the former way of reckoning, we are accustomed to say, that when the Sun comes to Libra, he has no declination, that the days and nights are then equal all over the earth, except at the poles; and that is the beginning of day at the South Pole, and the end of day at the North Pole.—Boundaries and Contents.-Libra is bounded on the north by Mons Maenalus and Serpens, east by Scorpio, south by Centaurus and Lupus, and west by Virgo. It con- tains 51 stars, two of which are of the 2d magnitude, one of the 3d, eight of the 4th, &c. . a Zuben el Genubi, situated on the Ecliptic, and "in the Southern Scale, rises on the E. S. E. point of the compass, at London; its right ascension is 2200 11' 18"; its declin. 15° 14' 28° S. a is a double star, and the mean right ascension of the two stars may be taken at 14 ho. 40 mi. and 57";—their south- 'ern declination at 15° 15' 47". The times of their rising and culminating are shewn in the following Table, for the first day of each month in the year; Merid. Alt. 239 14, 32". #MONTH, I RISES. 1 CULM. MonTH, I RISEs. I ‘CULM. - l ho. mi. ho. mi. | ho. mi. ho. mi. Jan. 3 15 M. 6 26 M. Júly 3 30 A. 6 38 A. - Feb. 1 10 M. 4 14 M. Aug. I 30 A. 4 31 A. : Mar. I 11 15 A. 2 25 M. Sept. 11 25 M. 2 25 A. April 9 30 A. | 0 32 M. Oct. 9 30 M. 0 47 A. May || 7 40 A. | 10 41 A. | Nov. 7 35 M. 10 47 M. June I 5 50 A. | 8 39 A. Dec. 5 25 M. 8.43 M. Libra also denotes the ancient Roman pound, which was equal to about 5040 of our Troy grains. It was likewise the name of one of their gold coins, equal in value to 20 denarii. See Phil. Trans. vol. lxi. p. 462. - - LIBRARIAN, one who has the care of a library. LIBRARY, an edifice, or an apartment in a building, fitted . up for the reception of books. The term is also frequently applied to the books themselves, with scarcely any reference to the building. Some authors refer the origin of libraries to the Hebrews, who were always careful to preserve their sacred books, and such memorials as regarded their ancestors. This method was imitated by the Egyptians, whe, next to the Israelites, were the first to erect libraries. Many famous libraries have existed in different periods of time, among which, that of Alexandria was the most remarkable. When , destroyed by the Saracens, it consisted of 700,000 volumes, and in it perished the learning of the ancient world. In former times every large church had its library, but at present the most distinguished in this country are the Bodleian at Oxford, and the Cottonian in the British Museum. LIBRATION OF THE EARTH, is a term applied by some astro- nomers to that motion, whereby the earth is so retained within its orbit, as that its axis continues constantly parallel to the axis of the world. This Copernicus calls the motion of libra- tion, and may be illustrated thus: Suppose a globe, with its axis parallel to that of the earth, painted on the flag of a mast, moveable on its axis, and constantly driven by an east wind, while it sails round an island; it is evident the painted globe will be so librated as that its axis will be parallel to that of the world, in every situation of the ship. LIBRATION of the Moon, in Astronomy, is more particularly applied to denote an apparent irregular libratory motion of that body about her own axis, whereby we see a little more than one-half of the lunar disc; or rather, it is in consequence of our seeing more than one-half of it, that the moon appears to have such a motion; for although the term libration, from the Latin libratio, to balance, agrees, perfectly well with the appearances observed, still it must not be understood in a pºsitive sense, the appearance itself arising from a totally different cause from that which the word seems to indicate. In order to illustrate this, let us conceive a visual ray drawn from the centre of the earth to the centre of the moon: the plane drawn through the latter centre perpendicularly to this ray, will cut the lunar globe according to the circumference of a circle which is, with respect to us, the apparent disc. If the moon had no real rotatory motion, its motion of revolution solely would discover to us all the points of its surface in suc- cession: the visual ray would therefore meet that surface suc- cessively in different points, which to us would appear to pass the one after the other, to the apparent centre of the lunar disc. The real rotatory motion counteracts the effects of this apparent rotation, and brings back constantly towards us the same face of the lunar globe. © Suppose, now, that the rotation of the moon is sensibly uni- form; that is to say, that it does not partake of any periodical inequalities, (this supposition is at least the most natural which we can make, and it is conformable to observations;) then one of the causes which produce the libration will become evident; | for the motion of revolution partaking of the periodical inequa- lities, is sometimes slower, sometimes more rapid: the apparent rotation which it occasions cannot, therefore, always exactly counterbalance the actual rotation, which remains constantly the same; and these two effects will surpass each other by turns. The points of the lunar globe ought, therefore, to appear turning sometimes in one direction, sometimes in another, about its centre; and the resulting appearance is the same as if the moon had a little vibratory balancing from one side to the other of the radius vector drawn from its centre to the earth. It is this which is named the libration in longitude. Several accessory but sensible causes modify.this first result, The spots of the moon do not always retain the same elevation | above the plane of its orbit; indeed some of them, by the effect of the rotation, pass from one side of this plane to the opposite | side. These circumstances indicate an axis of rotation which is not exactly perpendicular to the plane of the lunar orbit; but according as this axis presents to us its greater or its smaller obliquity, it must discover to us successively the two poles of rotation of the lunar spheroid: hence it is we per- ceive, at certain times, some of the points situated towards | these poles, and lose the sight of them afterwards, when they arrive nearer, the apparent edge: this is called the libration in latitude. It is but inconsiderable, and therefore indicates that the equator of the moon differs very little in position from the plane of its orbit. Finally, a third illusion arises from the observer being placed at the surface of the earth, and not at its centre. To- wards this centre it is that the moon always turns the same face; and the visual ray drawn thence to the centre of the moon would always meet its surface at the same point, abstracting from the preceding inequalities. It is not the same with respect to the visual ray drawn from the surface of the earth; for this ray makes a sensible angle with the former, by reason of the proximity of the moon; this angle is, at the horizon, equal to the horizontal parallax: in consequence of this difference the apparent contour of the lunar spheroid is not the same for the centre of the earth, and to an observer placed at its surface. This, when the moon rises, causes some points to be discovered towards its upper edge, which could not have been perceived from the centre of the earth: as the moon rises above the horizon, these points continue to approach the upper edge of the disc, and at length disappear, while others become visible to its lower edge : the same effect is continued during all the time that the moon is visible; and, as the part of its disc which appears highest at its rising is found lowest at its setting, these are the two instants when the difference is most perceptible. Thus the lunar globe, in its diurnal motion, appears to oscillate about the radius vector drawn from its centre to the centre of the earth. This pheno- menon is designated by the name of diurnal libration. LICENSE, in Law, is a power or authority given to another io do some lawful act. A license is personal, and cannot be transferred to another without the sanction of the original authority. Licenses are of various kinds, and encircle almost every department of law, of commerce, and of other actions in their wide embrace. - - - * LICENTIATE, among us is generally understood of a phy- sician, who has a license to practice granted him by the col- 7 'G •º 574 L I F DICTIONARY OF MECHANICAL SCIENCE. lege of physicians, or by the bishop of the diocese. A person practising physic without such license, in case his patient dies under his hands, is guilty of felony in the eye of the law. . . LICHEN, in Botany, a name borrowed by the Romans from the Greeks for the disease called a tetter or ringworm, and applied by both to a plant of a mossy nature, growing on stones, which was thought to be a cure for such complaints. # LIE, in Morals, denotes a criminal breach of veracity. Arch- deacon Paley, in treating of this subject, observes, that there are falsehoods which are not lies; that is, which are not cri- minal: and there are lies, which are not literally and directly false. LIEGE, LeGUIs, in Law, properly signifies a vassal, who holds a kind of fee, that binds him in a closer obligation to his lord than other people. - LIENTERY, a flux of the belly, in which the aliments are discharged as they are swallowed, or very little altered in colour or substance. - LIEUTENANT, an officer who supplies the place, and dis- charges the office, of a superior in his absence. Of these, some are civil, as the lords-lieutenants of kingdoms, and the lords-lieutenants of counties; and others are military, as the lieutenant-general, lieutenant-general of the, artillery, lieu- tenant-colonel, lieutenant of artillery of the Tower, lieutenants of horse, foot, ships of war, &c. LIFE, a term that implies the existence and duration of soul and body, or the period of their union. LIFE ANNUITI Es, are such periodical payments as depend on the continuance of some particular life or lives; and they may be distinguished into lives, to commence immediately; and annuities, to commence at some future period, called reversionary annuities. The value or present worth of an annuity for any proposed life or lives, it is evident depends on two circumstances; the interest of money, and the chance or expectation of the con- tinuance of life. Upon the former only depends the value or present worth of an annuity certain, or that which is not sub- ject to the continuance of a life or other contingency; but the expectation of life being a thing not certain, but only possessing a certain chance, it is evident, that the value of the certain annuity, as stated above, must be diminished in proportion as the expectancy is below certainty; thus, if the present value of an annuity certain be any sum, as suppose £100, and the value and expectancy of the life be one-half, then the value of the life annuity will be only half of the former, or £50; and if the value of the life be only one-third, the value of the life annuity will be but one-third of £100, that is, £33.6s. 8d. and S0 OI). The measure of the value or expectancy of life, depends on the proportion of the number of persons that die, out of a given number, in the time proposed; thus, if fifty persons die out of one hundred, in any proposed time, then half the number only remaining alive, any one person has an equal chance to live or die in that time, or the value of his life for that time is one-half: but if two-thirds of the number die in the time proposed, or only one-third remain alive, then the value of any life is one- third; and if three-quarters of the number die, or only one- quarter remain alive, then the value of any life is but one- quarter; and so on. In these proportions then must the value of the annuity certain be diminished, to give the value of the life annuity. It is plain, therefore, that in this business it is necessary to know the value of life at all the different ages, from some table of observations on the mortality of mankind, which may shew the proportion of the persons living, out of a given number, at the end of any proposed time ; or from some certain hypothesis, or assumed principle. It may not, there- fore, be improper to insert here a comparative view of two of the principal tables that have been given of this kind, as the following, where the first column shews the age, and the other columns the number of persons living at that age, out of 1000 born, or of the age 0, in the first line of each column. The uses of these tables may be exemplified in the following problems:— Problem 1–To find the Probability or Proportion of Chance, that a Person at a given Age continues in being a proposed number of Years.-Thus, suppose the age to be 40, and the number of - L I F years proposed 15; then to calculate by the table of the proba- bilities for London, in table 1, against 40 years stands 214 ; and against 33 years; the age to which the person must arrive, stands 120; which shews, that of 214 persons who attain to the age of 40, only 120 of them reach the age of 55, and conse- quently 94 die between the ages of 40 and 55. It is evident, therefore, that the odds for attaining the proposed age of 55 a",. to º as 9 to 7 nearly. - y *"oblem. 2.--To find the Value of an Annuity for a proposed Life.--This problem is resolved #. table 2, ### j the given age, and under the proposed rate of interest; then the corresponding quantity shews the number of years' pur- chase required. For example, if the given age be 36, the rate of interest 4 per cent. and the proposed annuity £250. Then in the table it appears, that the value is 12.1 years purchase, or 121 times £250, that is, £3025:1. After the same manner, the answer will be found in any other case falling within the limits of the table. But as there may sometimes be occasion to know the values of lives computed at higher rates of interest than those in the table, the two following practical rules are ºned by which the problem is resolved independent of a DICS. Rule 1. When the given age is not less than 45 years, nor greater than 85, subtract it from 92; then multiply the re- mainder by the perpetuity, and divide the product by the said remainder added to 23 times the perpetuity; so shall the quotient be the number of years' purchase required. Where note, that by the perpetuity is meant the number of years' pur- chase of the fee-simple; found by dividing 100 by the rate per cent." at which interest is reckoned. - Example. Let the given age be 50 years, and the rate of interest 10 per cent. ...Then subtracting 50 from 92, there remains 42; which multiplied by 10 the perpetuity, gives 420 ; and this divided by 67, the remainder increased by 2 times ió the perpetuity, gives 63 nearly, for the number of years' pur.” chase. Therefore. Supposing the annuity to be £100, its value in present money will be £630. Rule 2. When the age is between 10 eight-tenths of what it wants of 45, per cent, increased by value of a life of 45 ye and 45 years, take which divide by the rate 12; .*.*. be added to the º ars, foun the preceding rul will be obtained the number of yº bº. in j º: For example, let the proposed age be 26 years, and the rate of interest 5 per cent. Here taking 20 from 45, there remains 25: eight-tenths of which is 20; which divided by 6.2, quotes 3:3: and this added to 98, the value of a life of 45, found by the former rule, gives 13 for the number of years' purchase that a life of 20 ought to be valued at. And the conclusions derived by these rules are said, by Simpson, to be so near the true values, computed from real observations, as seldom to differ from them by more than one-tenth or two-tenths of one year’s purchase. - The observations here alluded to, are those which are founded on the London bills of mortality. And a similar method of: solution, accommodated to the Breslaw observations, will be as follows: viz. Multiply the difference between the given age and 85 years by the perpetuity, and divide the product by eight-tenths of the said difference, increased by double the perpetuity for the answer; which, from 8 to 80 years of age will commonly come within less than one-eighth of a years p"; of the#}. } - "oblem 3–To find the Value of an Annuity for the longest o two Lives ; that is, for as long as º: of them ºff. in ::::::/ In table.8, find the age of the youngest life, or the nearest to it, in col. 1, and the age of the elder in col. 2; then against this last is the answer in the proper column of interest. Example. So if the two ages be 15 and 40, then the value of the annuity upon the longest of two such lives, : is 211 years’ purchase, at 3 per cent. or 179 . . . . . . . . . . . . . - at 4. . . . . . . . • or 167 . . . . . . . . . . . . . . at 5 . . . . . . . Q Note. In the last two problems, if the younger age, or the rate of interest, be not exactly found in the tables, the nearest to them may be taken ; and then, by proportion, the value for the true numbers will be nearly found. I, I F 575 DICTIONARY OF MECHANICAL scIENCE. L 1 F * Table I. Exhibiting the Decrease of Life, at all Ages, from 1 Year to 90, as deduced from the Bills of Mortality in London and Northampton. W Ages. London. Noºr- ; Ages. London. Noºr. i Ages. London. Noºr- Ages. London. Noºr — 3 e ſº i 0 1000 1000 23 310 426 : 46 174 275 69 56 113 l 680 738 24 305 419 47 167 268 70 52 106 2 548 628 ; 25 299 412 48 I59 261 71 47 99 3 492 585 26 294 405 49 153 254 & 72 43 92 4 452 562 i 27 288 398 50 147 247 $ 73 39 85 5 426 544 28 283 391 ; 51 141 239 : 74 35 78 6 410 530 ; 29 278 384 : 52 135 232 3 75 32 71 7 397 518 ; 30 272 378 ; 53 I 30 225 76 28 64 8 388 510 31 266 372 54 125 218 77 25 58 9 380 504 i 32 260 366 i 55 120 21 I 78 22 52 10 498 33 254 || 360 56 116 204 79 I9 46 11 § 493 : 34 248 354 ; 57 111 || 19: § 30 17 40 i: | 3gi | 4:3 33 243 || 348 58 || 106 || 190 3 81 14 34 13 356 484 : 36 236 342 ; 59 101 183 : 82 12 28 14 351 480 ; 37 230 336 60 96 176 & 83 10 23 15 347 475 38 224 330 i 61 92 169 & 84 8 19 16 343 470 39 218 324 62 87 162 : 85 7 16 17 338 465 40 214 317 ; 63 83 155 : 86 6 13 18 334 459 : 41 207 310 ; 64 78 148 ; 87 5 11 19 329 453 ; 42 201 303 ; 65 74. 141 ; 88 4 8 20 325 447 : 43 194 296 66 70 134 & 89 3 6 21 321 440 $ 44 187 289 & 67 65 127 & 90 2 4. 22 316 433 ; 45 180 282 ; 68 61 120 ; tº º tº º tº e -º-º: TABLE II. Shewing the Value of an Annuity on One Life, or Number of Years' Annuity in the Value, supposing Money to bear Interest at the several IRates of 3, 4, and 5 per Cent. A Years' value at l Years' value at Years’ value at 3 A Years’ value at Years’ value at Years’ value at ge. 3 per Cent. 4 per Cent. 5 per Cent. ; ge. 3 per Cent. 4 per Cent. 5 per Cent. 6 18 - 8 16 - 2 14 * 1 ; 41 13 - 0 11 * 4 10 - 2 7 18 - 9 16 °3 14 • 2 # 42 12 8 11 - 2 10 * 1 8 19 - 0 16 ° 4 14 • 3 $ 43 12 6 11 - 1 10 * 0 . 9 19 - 0 16 ° 4 14 • 3 44 12 - 5 11 - 0 9 • 9 10 19 • 0 16 ° 4 14 • 3 i 45 12.3 10 - 8 9 * 8 d 11 19.0 16 ° 4 14 • 3 : 46 12 - 1 10 - 7 9 - 7 12 18 - 9 16 ° 3 14 - 2 47 11 - 9 10 - 5 9 * 5 13 18, 7 16 - 2 14 * 1 i 48 11 * 8 10 - 4 9 * 4 14 18 - 5 16 - 0 14 - 0 49 11 * 6 10 - 2 9 • 3 15 18, 3 15 8 13 - 9 50 11 * 4 10 - 1 9 • 2 16 18 - 1 15 6 13 - 7 51 II - 2 9 - 9 9 * 0. 17 17. 9 15 ° 4 13 - 5 52 11 * 0 9 • 8 8 - 9 T8 17. 6 15 - 2 13° 4 53 10 - 7 9 , 6 8 - 8 19 17 - 4 15 - 0 13 - 2 54 10 * 5 9 - 4 8.6 20 17 - 2 14 8 13 * 0 55 10' 3 9 • 3 8 - 5 21 17 - 0 14 - 7 12 - 9 56 10 - 1 9. 1 8 - 4 22 16 - 8 14' 5 12 - 7 57 9 * 9 8 - 9 8 - 2 23 16 - 5 14 ° 3 12 - 6 58 9 • 6 8.7 8 - 1 24 16 - 3 14 * 1. 12 - 4 $ 59 9 * 4 8 : 6 8 - O • 25 16 - 1 , 14 ° 0 12.. 3 ; 60 9 - 2 8 - 4 7. 9 26 15 - 9 13 * 8 12 - 1 61 8 ° 9 8 - 2 7.7 27 15 - 6 13 - 6 12 - 0 $ 62 8 - 7 8 - 1 7. 6 28 15 - 4 13° 4 I 1 - 8 $ 33 8 * 5 7. 9 7 * 4 29 I5 - 2 13 - 2 11 - 7 64 8 - 3 7.7 7 - 3 30 15 - 0 13 - 1 11 : 6 65 8 * 0. 7 - 5 7 - 1 31 14" 8 12 - 9 11 * 4 & 66 7 - 8 7 - 3 6 - 9 32 14 • 6 12 - 7 I 1 - 3 & 67 7 6 7 - 1 6 - 7 38 14 - 4 12 - 6 11 - 2 $ 68 7' 4 6 • 9 6 • 6 34 14 ° 2 12" 4 11 - 0 ; 69 7 - 1 6 - 7 6 • 4 35 14 - 1 12 3 10 - 9 § 70 6 - 9 6 • 5 6 - 2 36 13 - 9 12 - 1 10 - 8 : 71 6 - 7 6 • 3 6 - 0 37 13 - 7 11 * 9 10 - 6 72 6 * 5 6 - 1 5 • 8 38 . 13 * 5 11 * 8 TO 5 3 73 6 - 2 5 • 9 5 • 6 39 13 • 3 11 * 6 10 * 4 ; 74 5 ° 9 5.6 5 * 4 40 13 - 2 II • 5 10 * 3 ; 75 | 5 • 6 5 * 4 5 - 2 576 B I F DIGTIONARY OF MECHANICAL SCIENCE. L I F TABLE III, For the Value of an Ahnuity upon the Longer of Two given Lves. ;Age-of . - Age of 4. Value at , 4 Value at l Value at . ; Age of Age of H Value at Value at Value-at. Younger, { Elder. . . . 3 per Cent, .4 per Cent. {. 5 per Cent. Younger. º Elder. 3 per Cent. 4 per Cent. | 5 per Cent. H0 23:4 199 || 17-i i 55 17-4 15° 1 13°4 t 15 . 229 19:5; H . 16.8 R 60 17-0 1 4-8 13°2 : 20 22.85 Hø. 1 1 16-6. ; 30 65 I6'6 14°5 . . 12.9 25 2252 .#38 16-4 . ... " zo 16:1 14°1 | 12°6 30. 2ā'9 18.6 16'2 W5 ! {5°6’ 13-7 12.2 , 35. 21-6 184 16:1 —|—|—|--— 10 40, 21:4 18°3 16-0 # 35 18-3 15'8 || 1348 . . 45. 21.2 , 18.2 15 9 i 40 17.8 15°4 13'5 d 50 20:9 l'8-0 || 15'8 . 45 T7-4 15:1 | 13°3 55 20-7 17-8 & 157 . . 350 17, 1 14-8 ; 13° 1 60 20:4 17.6 ſ 15'5 35 55 16-7 14°5 12*9 65 20°2 17.4 ± 1.5-2 . - 60 l6-3 14-2 || 12*7 70 I959 17.2 14.8 $65 15'8 13-8 ; 12% 75 19°5 16-8 ; 14-3 . 70 15°3 13°4 + 12-0 º *— — — *: • *- : — +---—º- $75 ‘A4°S 13-0 11-6 - 15 33.8 19-3 ; 16-7 ** -— — — — — —— 20 32.3 18.9 16°4 40 {7-3 15-0 || 133 25 21:9 18-6 ſ 16.2 35' 168 14.6 13-0 30 21-6 i8-3 16-0 50 #6'3 14-2 12-7 35 21:3 18-1 || 15.9 40 55 I5'9. 13-9 | 12:4 s 40 24.1 17.9 : 157 60 #5'4' 13.5 1241 15 45 20:9 17:8 15.6 3 65 14.9 13- 1 : 11.8 50 30-7 17:6 15.4 3 70 14.5 12.7 11-4 55: . 20-4 17.4 15°3 3 75 * †4-0 12-3 11:0 - 60 20*1 17-2 . 15°2 - º —1– | 65 19.8 16.9 15'0 i 45 16.2 14°2 12.8 70 , 19:4 16.6 14-7 . 50 157 13.8 12.5 75 | 18.9 I6'3 14.4 55 152. 13-4 12-1 ," “ . . . . . . . . . . . . . .” - d. , . . . . . . . . -- . . #5 160 - 14-7 12.9 11-7 20 21-6 18°3 15'8 65 14° 1 12.5 11:4 T ºff 21:1 #5 | is; ; 70 13-6 T2:0 T 11-0 | 30- 90.7 17.6 15-3 ; 75 13-1 11°6 || || 0-6 | 85 20:4 17.4 15:1 3 -)--—j— —— | 40 20:1 17.2 T5:0 | 50 15:0 133 12.1 20 43 19.9 17:0 149 : | 55 14.5 12.9 11.7 § 50 19:6 168 147 50 | 99 13.9 12.4 11:3 | 55 10-4 166 14°5 . | 65 13:3 12:0 10°9 : 60 19:1 16:3 143 3 | 70 12.8 II* 5 10:5 65 18.7 160 14.1 : | 75 I2'3 11-0 10:1 il. 70 182 157 138 : —— -— o – | 75 17.7 . 15°3 13.5 ; | 55 13.6 12.4 11:3 r — - — : | | 60 13-0 11:9 10.9 il 25 20.3 17-4 15.1 : 55 65 T2-4 11:3 10:5 * 30 fg'8 17:0 14:9 $ | 70 11°8 10°8 10-0 {| 35 19:4 167 147 : ...] 75 11.8 10°3 9°5 ..]. 40 19.2 16-5 145 : —— - : ,- — | 45 f$9 163 143 : | 9 12.2 11.2 10°5 25 | 50 18°7 16:1 14.2 : 60 65 11:5 TO-6 10-0 | 55 18°4 15'9 14.0 | 70 10°9 10:1 ‘9-5 'l 60 18:0 15'6 138 : | 75 10°3 9°5 19-0 ... 65 17:6 15°3 13-6 : —1–H–F– ––––. | 70 izº 150 138 || 65 10-7 10-0 9.4 : 75 I6.7 14°6 125 $ 65 || 70 10-0 9:4 -8.9 il. – + 4. —- . j 75 9°3 337 "8-3 j 30 19:3 16.6 14.5 : †— ——|— —— • I 35 18:8 162 14:2 ºf 70 || 79 92 86 82 30 || 40 184 15.9 14-0 . * | 75 : 8°4 7-9 7-6 | 45 18:1 156 13-8 ; --- —— -- t 50 Í7.8 15°4 l 3-6 ; 75 : 75 - 7-6 7.2 *6-9 LIFE Preserver, Scheffek's.--To the specific gravity of volume of water, very little notice, for practical purposes, has been taken. The inquiries conducted by Mr.Robertson, So- cretary to the Royal Society, about the year 1760, are now 4. : almost forgotten ;” and but few individuals can be found who the human body very little attention has been directed; and of the éxperiments, very small in number, which have been per- formed to ascertain its weight compared with that of an equal are fully aware, that man is so constructed, as actually to float * From the last line of the table published by Mr. Robertson, (Phil. Trans. vol. 50, art. 5,) we derive a knowledge of the medium of All the cir- | cumstances; of height, weight, &c.; particularly the miean specific gravity, | 0, 891, which is about 1-9th less than common water. f; I F 5?? DICTIONARY OF MECHANICAL SCIENCE. i., f G when placed upon water, although not so superficially or in such position without great care and exertion, as to preserve an adequate entrance for air into the organs of respiration. . The fact, however, is, that we are calculated to float conveni: ently for a considerable length of time, if we are possessed of sufficient self-confidence, and some art in balancing the body. Not always long enough, it must be admitted, for complete pro- tection against the disasters which happen on the ocean, or even on rivers and canals; on all of which such multitudes are now scattered, by the industrious and adventurous spirit of the age. Nor, in cases of shipwreck, does the casual additional support of a mast, an oar, or a plank, always suffice to lend that buoyancy, on account of their unsteadiness, which the perils of the deep often demand. More fixed appendages, of various descriptions, have lately been introduced to the notice of the public, under the appellation of life-preservers; and boats upon a similar principle, under the name of life-boats, have been constructed, so as to be secured against sinking, even when filled with water and in the most tempestuous weather, for the purpose of rescuing from destruction those “who are ready to perish.” tº It has happened unfortunately with respect to most of the life- preservers, as they have been termed, that some difficulty has attached to their conveyance, application, or effect, which has either rendered them usehess, or much less effectual than from their principle might have been expected; and accordingly in succession they have been disregarded. The importance of the object would not allow the attempt to be abandoned, and ingeni- ous men still continue to exercise their inventive powers, in ob- viating the defects of their predecessors. The buoyancy of cork, which was formerly much resorted to, has given way to the su- perior buoyancy of air, and jackets distended with this very light fluid, or attached vessels of other forms filled with it, have been occasionally adopted. The effort has at length been suc- cessful; and air has become, by the invention of Scheffer, in another than the acknowledged sense of the term, a perfect life-preserver. The simplicity and con- venience of Scheffer's Life- preserver must be at once perceived. It consists of a hollow cylinder, formed without a seam, and perfect- ly air-tight, bent when dis- tended with air and ready for use, as in fig. 2: or it is what may be termed a cy- * lindrical ring, also without = a seam, and also without # the break which appears in § the former, represented in S fig.1. Of this ring, the exter- sº º == nal diameter is generally sº ..., &_ about 22% inches, the inter- * - º nal diameter about 12, and the diameter of the part containing the air about 5}, the dimensions varying of - course, by being specially adapted to the size of the person by whom it is designed to be employed. By its form, it is well fitted for the place which it occupies, being situated beneath the arms; it does not press painfully upon the chest, and the suspension or support being placed so high, enables the lower part of the body and extremities, to act as a pendulum, in keeping the wearer vertical, or restoring him to that position, if thrown aside by the force of the waves. The two holes, one in each ring, the only openings, receive a small stop-cock, to which an ivory pipe is fixed. Through this pipe the air is injected by the mouth, and retained by the stop-cock; the adjustment and inflation only occupying the short space of one minute: when unexpanded, it folds up into a very small compass, so as to be conveyed in the pocket; and is also very portable, its weight, as I ascertained by weighing one of them, being but twelve ounces. . The public at Brighton last summer, had several opportuni- tics of seeing Scheffer supported in the sea by his very valu- able eontrivance. He was taken in a boat about a mile from the shore, and there threw himself into the water. He became immediately buoyant, amused himself with swimming, or allowing himself to be tossed about by the waves, for more than an hour. He had along with him a spare preserver, by which he managed to shew, that in the manner represented in the vignette, he could have placed it upon a person in danger of sinking, and even have used several for different persons in simi- lar danger, who would all be rendered safe, until they could have been collected and preserved by a life-boat. His experiment succeeded to the satisfaction of a large number of spectators. The situation from which the exhibition was viewed, the head of the chain pier, was particularly favourable for watching the motions of the adventurer: and the sea being very rough, gave occasion to observe how effectually the buoyant girdle control- led that power, by which an unprotected man must have been speedily ingulfed. LIFTS, certain ropes descending from the cap and mast head. Their use is to keep the yard in equilibrio, or to pull one of its extremities higher than the other, if occasion requires; but particularly to support the weight of it when a number of seamen are employed thereon to furl or reef the sail. In some merchant vessels the lifts of the topsail yards, called the top- sail lifts, are also used as sheets to extend the clues of the top- gallant sail. The yards are said to be squared by the lifts, when they hang at right angles with the mast, i. e. parallel with the horizon when the vessel is upright in the water. LIGAMENT, in Anatomy, a strong compact substance, serv- ing to join two bones together. A ligament is more flexible than a cartilage, not easily ruptured or torn, and does not yield, or at least very little, when pulled. * LIGATURE, in Surgery, is a cord, band, or string; or the binding any part of the body with a cord, band, fillet, &c. whe- ther of leather, linen, or any other matter. Ligatures are used to extend or replace bones that are broken or dislocated; to . tie the patients down in lithotomy and amputations; to tie upon the veins in phlebotomy, on the arteries in amputations, or in large wounds; to secure the splints that are applied to fractures; to tie up the processes of the peritonaeum with the spermatic vessels in castration; and lastly, in taking off warts or other excrescences by ligature. Ligature is also used to signify a kind of bandage or fillet, tied round the neck, arm, leg, or other part of the bodies of men or beasts, to divert or drive off some disease, accident, &c. - LIGATURES, among printers, are types consisting of two letters or characters joined together; as ff, fi, fl. The old editions of Greek authors are extremely full of ligatures; the ligatures of Stephens are by much the most beautiful. Some editions have been lately printed without any ligatures at all; and there was a désign to explode thern quite out of printing. Had this succeeded, the finest ancient editions would, in time, have grown useless: and the reading of old manuscripts would have been rendered almost impracticable to the learned them- selves. - - LIGHT, is that principle or substance which renders objects perceptible to our sense of seeing. This is, perhaps, one of the most interesting subjects that falls under the contempla- tion of the philosopher; at the same time it must be acknow- ledged to be one that is as little understood, and upon which opinions are as much divided, as any of the most abstruse sub- jects of philosophical inquiry. Some consider light as a fluid per se; while others consider it merely as a principle, and attribute it to a sort of pression, or vibration propagated from the luminous body through a subtile ethereal medium. But notwithstanding the imperfection of our knowledge, with re- gard to the nature and cause of light, repeated experiments and observations have made us acquainted with several of its properties; such as its INFLEction, REFLection, REFRACTION, &c.; for which, see the respective articles. - . . . Of the Motion of Light.—The ancients considered light as propagated from the sun and other luminous bodies instantane- ously; but the observations of the moderns have, shewn that this was an erroneous hypothesis, and that light, like any other projectile, employs a certain time in passing from one part of space to another, though the velocity of its motion is truly astonishing, as has been manifested in various ways; and, 7 H 578 L I G L I G DictionARY of MECHANICAL science. first, from the eclipses of Jupiter’s satellites. . It was observed by Roemer, that the eclipses of those satellites happen some- times sooner and sometimes later than the times given by the tables of them; and that the observation was before or after the computed times, according as the earth was near to, or far- ther from Jupiter, than the mean distance. Hence Roemer and ‘Cassini both concluded that this circumstance depended on the distance of Jupiter from the earth: and that, to account for it, they must suppose that the light was about fourteen minutes in crossing the earth’s orbit. This conclusion, however, was afterwards abandoned and attacked by Cassini himself. But Roemer’s opinion found an able advocate in Dr. Halley; who removed Cassini's difficulty, and left Roemer's conclusion in its full force. Yet, in a memoir presented to the academy in 1709, M. Maraldi endeavoured to strengthen Cassini's argu- ments, when Roemer's doctrine found a new defender in Mr. Pound; see Phil. Trans. No. 136. It has since been found, by repeated observations, that when the earth is exactly between Jupiter and the sun, his satellites are seen eclipsed about eight minutes and a quarter sooner than they could be according to the tables; but when the earth is nearly in the opposite point of its orbit, these eclipses happen about eight minutes and a quarter later than the tables predict them. Hence then it is certain that the motion of light is not instantaneous, but that it takes up about sixteen minutes and a half of time to pass over a space equal to the diameter of the earth's orbit, which is near 190 millions of miles in length, or at the rate of near 200,000 miles per second; a conclusion which is placed beyond every possibility of doubt; by the aberration of the stars discovered by the celebrated Dr. Bradley. Of the Momentum of Light—We have before observed, that much diversity of opinion existed with regard to the materiality or immateriality of light, viz. whether it is a fluid per se, or b y p 5 whether it be merely a principle consisting in pulsations or vibrations; and thus rendered sensible to our optic nerve as sound is to our organs of hearing. The ingenious Dr. Franklin expresses his dissatisfaction with the doctrine, that light con- sists of particles of matter continually driven off from the sun's surface with so enormous a swiftness. “Must not,” says he, “the smallest portion conceivable, have, with such a motion, a force exceeding that of a 24-pounder discharged from a cannon 2 Must not the sun diminish exceedingly by such a waste of mat- ter; and the planets, instead of drawing nearer to him, as some have feared, recede to greater distances, through the lessened attraction ? Yet these particles, with this amazing motion, will not drive before them, or remove, the least and slightest dust they meet with ; and the sun appears to continue of his ancient dimensions, and his attendants move in their ancient orbits.” He therefore conjectures that all the phenomena of light may be more properly solved, by supposing all space filled with a subtile elastic fluid, not visible when at rest, but which, by its vibrations, affects that fine sense in the eye, as those of the air affect the grosser organs of the ear; and even that different degrees of the vibration of this medium may cause the appear- ances of different colours. And the celebrated Euler has main- tained the same hypothesis, urging some further objections to the materiality of light, beside those of Dr. Franklin, as above stated. These objections, however, Dr. Horsley took consider- able pains to obviate, though some of them still remain in full force. Others, on the contrary, have attempted to prove the materiality of light, by determining the momentum of its com- ponent particles, or by shewing that they have a force so as, by their impulse, to give motion to light bodies. M. Homberg, (1708,) imagined that he could not only disperse pieces of ami- anthus, and other light substances, by the impulse of the solar rays, but also that by throwing them upon the end of a kind of lever, connected with the spring of a watch, he could make it move sensibly quicker; from which, and other experiments, he inferred the weight of the particles of light. And Hartsocker made pretensions of the same nature. Mairan made other experiments of a more accurate kind, with- out the effects which the former had imagined, and which even proved that the effects mentioned by them were owing to cur- rents of heated air produced by the burning glasses used in their experiments, or some other causes which they had over- looked. Mr. Michell endeavoured to ascertain the momentum But M. Du Fay and M. of light with still greater accuracy, and his endeavours were not altogether without success. Having found that the instru- ment he used acquired, from the impulse of the rays of light, a velocity of an inch in a second of time, he inferred that the quantity of matter contained in the rays falling upon the in- strument in that time, amounted to no more than the 12 hundred millionth part of a grain. In the experiment, the light was co- lected from a surface of about three square feet; and as this surface reflected only about the half of what fell upon it, the quantity of matter contained in the solar rays, incident upon a Square foot and a half of surface, in aisecond of time, ought to be no more than the 12 hundred millionth part of a grain, or upon one square foot only, the 18 hundred millionth part of a grain. But as the density of the rays of light at the surface of the sun, is 45,000 times greater than at the earth, there ought to issue from a square foot of the sun's surface, in one second of time, the 40 thousandth part of a grain of matter; that is, a little more than two grains a day, or about 4,752,000 grains, which is about 670 pounds avoirdupois in 6000 years, the time since the creation; a quantity which would have shortened the sun's semidiameter by no more than about 10 feet, if it be sup- posed of no greater density than water only. But, after all, these experiments and computations must be considered as very vague and unsatisfactory; and it may be added, that the material hypothesis is almost wholly rejected by the most cele- brated chemists and philosophers of the present day. - LIGHT, is used in contradistinction to laden; a ship is there- fore said to be light, when she has no cargo, or is not sufficiently ballasted. - LIGHTER, a large open flat-bottomed vessel, employed to carry goods to or from a ship. - - ... • Ballast Lighter, is a vessel fitted up to heave ballast from the bottom of a harbour or river, and to carry it to or from ships. Covered or Close LIGHTER, is one furnished with a deck, in order to contain those merchandises which would be damaged by accidental wet, as also to prevent pillage. . LIGHT-HOUSE, a sort of tower erected upon a headland or point on the sea coast, or upon some rock in the Sea, and hav- ing a great fire or light, formed by candles, &c. upon its top, in the night time, which is constantly attended by some careful person, so as to be seen at a great distance from the land. Its use is to direct the shipping on the coast, that might otherwise run ashore, or steer an improper course. The two most cele- brated light-houses on the coast of Great Britain, are the Eddystone and Bell-rock Light: the former erected by the cele- brated Smeaton. We have, under the word PHARos, given the details of the erection and peculiar construction of the latter, which was executed by Robcrt Stevenson, Esq. from a model, and of the same dimensions, of the Eddystone, with the im= provements on lighting which the recent progress in optics allowed the engineer to make. - - Floating LIGHT, differs from the preceding by its being erected on board a vessel which is strongly moored upon a sand or shallow, to warn ships from approaching too near it. LIGHTNING. It is now universally allowed, that lightning is really an electrical explosion or phenomenon. Philosophers had not proceeded far in their experiments and inquiries on this subject, before they perceived the obvious analogy be- tween lightning and electricity, and they produced many argu- ments to evince their similarity. But the method of proving this hypothesis was first proposed by Dr. Franklin, who, in the year 1749, conceived the practicability of drawing lightning from the clouds. See MeteorologY and Electricity. LIGHTROOM, in a ship of war, a small apartment, having double glass windows towards the magazine. It is used to contain the lights by which the gunner and his assistants are enabled to fill their cartridges with powder, to be ready for action. Large ships of war generally have two lightrooms, viz. the after lightroom, attached to the after magazine; and the fore lightroom, which gives light to the fore or great magazine. LIGNUM WITHE. The lignum vitae tree is a native of the West Indies, and the warmer parts of America: it rises to the height of forty feet, and measures from fifteen to eighteen inches in diameter; having a hard, brittle, brownish bark, not verythick. The wood is firm, ponderous, resinous, of a blackish yellow colour in the middle, and a hot aromatic taste. %, 22 H --- É * * H----- - - : • : ºr ; Shelter § V **:: ss==== º sis Sºs •. >ºt —w. L I. M. L I N 579 DICTIONARY OF MECHANICAL SCIENCE. LIGULATED, among botanists, an appellation given to such floscules as have a straight end turned downwards, with three indentures, but not separated into segments. : LIGUSTICUM, Lovage, a genus of plants belonging to the pentandria class; and in the natural method ranking under the 45th order, umbellatae. ... LIGUSTRUM, Privet, a genus of plants belonging to the diandria class; and in the natural method ranking under the 44th order, sepiariae. LIMB, the outermost border, or graduated edge, of a quad- rant, astrolabe, or such like mathematical instrument. The word is also used for the arch of the primitive circle, in any projection of the sphere in plano. Limb also signifies the outermost border or edge of the sun and moon; as, the upper limb or edge, the lower limb, the preceding limb or side; the following limb. Astronomers observe the upper or lower limb of the sun or moon, to find their true height, or that of the centre, which differs from the others by the semidiameter of the disc. - - LIMBERS, or LIMBER Holes, square holes cut through the lower part of a ship's floor timbers, very near the keel, forming a channel for water, and communicating with the pump well throughout the whole length of the floor. Every floor timber has two such holes cut through it, one on each side of the keelson. - LIMBert Boards, short pieces of plank, which form a part of the lining of a ship's floor close to the keelson, and immedi- ately above the limbers. They are occasionally removed to clear the limbers of any filth by which they may be clogged, so as to interrupt the passage of the water to the pump well. LIMBER Rope, a long rope frequently retained in the limber holes of a ship, in order to clear them, by pulling the rope back- wards and forwards, so as to loosen any dirt by which they may be choked. LIME, one of those earthy substances, which exist in every part of the known world; it is found purest in limestone, mar- ble, and chalk. None of these substances are lime, but are capable of becoming so by burning in a white heat. It may be also obtained perfectly pure by burning calcareous spars, and also by burning some pure white marbles. It may be procured also in a state of purity by dissolving oyster-shells in muriatic acid. It has been ascertained by Sir H. Davy to consist of oxygen and a metallic basis which he denominates calcium. LIMESTONE. The native indurated carbonate of lime. LIMIT, is a term used by mathematicians for some deter- minate quantity, to which a variable one continually approxi- mates, and may come nearer to it than by any given difference, but can never go beyond it; in which sense a circle may be said to be the limit of all its inscribed and circumscribed poly- gons; because these, by increasing the number of their sides, can be made to be nearer equal to the circle than by any space that can be proposed, however small it may be. LIMNING, the art of painting in water colours, in contra- slistinction to painting, which is done in oil colours. Limning is much the more ancient kind of painting. Till a Flemish painter, one John van Eyck, better known by the name of John of Bruges, found out the art of painting in oil, the painters all painted in water and in fresco, both on their walls, on wooden boards, and elsewhere. When they made use of boards, they usually glued a fine linen cloth over them, to prevent their opening; then laid on a ground of white; lastly, they mixed up their colours with water and size, or with water and yolks of eggs, well beaten with the branches of a fig tree, the juice whereof thus mixed with the eggs; and with this mixture they painted their pieces. In limning, all colours are proper enough, except the white made of lime, which is only used in fresco. The azure and ultramarine must always be mixed with size or gum ; but there are always applied two layers of hot size before the size colours are laid on : the colours are all ground in water each by itself; and, as they are required in working, are diluted with size water. When the piece is finished, they go over it with the white of an egg well beaten; and then with warnish, if required. * . To Limn, or Draw a Face in Colours. Having all the mate- rials in readiness, lay the prepared colour on the card even and thin, free from hairs and spots, over the place where the which will require about two hours. picture is to be. The ground being laid, and the party placed in a due position, begin the work, which is to be done in three sittings. At the first, you are only to dead-colour the face, At the second sitting, go over the work more curiously, adding its particular graces or deformities. At the third sitting, finish the whole, carefully remarking whatever may conduce to render the piece perfect, as the cast of the eyes, moles, scars, gestures, and the like. LINE, in Geometry, is, according to Euclid's definition, that which has length without thickness. Lines are either right or curved: A Right or Straight LINE, is that which lies all in the same direction between its extremes or ends. A Curve LINE, is that which continually changes its direction. Curve LINEs, are again divided into algebraical, geometrical, and mechanical, or transcendental. An Algebraical or Geometrical LINE, is that which may be expressed, that is, the relation between its absciss and ordinate, by an algebraical equation. And such lines are divided into orders, according to the dimensions of the equations by which they are represented. Mechanical and Transcendental LINEs, are those which cannot be expressed by finite algebraical equations. Besides the above distinctions, lines receive other denominations according to their absolute or relative positions, as parallel, perpendicular, oblique, tangen- tial, &c.; for which see the respective terms. LINEs have again other distinguishing appellations, as they are introduced into the different sciences of astronomy, geography, dialling, perspective, &c.; as, LINE of the Apsides; of the Nodes; Hori- zontal, Hour, Equinoctial, &c. Lines; each of which will be found illustrated under the respective articles. LINE also denotes a French measure of length, being the 12th part of an arch. - - - LINE, a general name given to the arrangement or order in which a fleet of ships of war are disposed to engage an enemy. This disposition, which is the best calculated for the operations of naval war, is formed by drawing up the ships in a long file, or right line, prolonged from the keel of the hindmost to that of the foremost, and passing longitudinally through the keels of all the others from the van to the rear, so that they are, accord- ing to the sea phrase, in the wake of each other. - In the line or order of battle, all the ships in which it is com- posed are close-hauled upon the starboard or larboard tack, about fifty fathoms distant from each other. A fleet is more particularly drawn up in the line when in presence of an enemy. It ought to be formed in such a mariner as that the ships should mutually sustain and reinforce each other, and yet preserve a sufficient space in their stations, to work or direct their move- ments with facility during the action. Thus they wiſ! be en- abled effectually to cannonade the enemy, without incommoding the ships of their own squadron. In a line of battle, the weathermost fleet, or that which, in sea language, has the wea- ther gage, is generally allowed to have the advantage, although there are several arguments on the other hand in favour of the leeside; accordingly, we shall endeavour to state the mutual advantages and disadvantages. Advantages of the Weather Gage.—1. The weather gage is the sooner clear of smoke; and of course, that line can better observe the signals which are spread than the ships to leeward can, which must have the continuance of both its own smoke and that of the enemy longer. 2. If the weather ships are more in number than the enemy's, they can detach some from their squadron, which bearing down upon the rear of the enemy, must infallibly throw them into disorder. 3. The fireships of the weather line can, when they are ordered, more easily bear down upon the enemy, than those of the lee can ply to windward, which can never be done against a line in action: but the weather fire- ships can bear down against all the resistance that can be made by the enemy. - Advantages of the Lee Line.—1. If one, two, or more of the ships to windward should be disabled, they must inevitably drive to leeward, and become a prey to the encomy. 2. The ships of the lee line can more readily bear away before the wind, and have their places supplied by ships from the corps-de- reserve, in case of being disabled, or meeting with any disaster. 3. The line to leeward can keep their ports longer open in a strong wind with a high sea, when those to windward in all probability may be obliged to shut the ports of their lower tier 580 L. L N L I N DICTIONARY OF MECHANICAL SCIENCE. of guns, to prevent the water from rushing in between decks, which may be attended with the most fatal consequences. 4, The lee line can more easily observe the men on the decks of the ships to windward, as they heel, and when the smoke does not intercept their sight; at which time the marines and topmen may easily take aim at and destroy them with muskets and carabines. . - The disadvantages of the weather line sometimes counter- balance the advantages above recited, viz. 1. If the sea is rough, and the wind boisterous, it cannot readily fight with the lower deck guns. 2. The weather line cannot decline the action without the dangerous expedient of forcing through the enemy’s line, and if it keeps the wind, the lee line may enclose and totally destroy it, especially if it is inferior in numbers to the latter; or if the ships thereof are in a bad condition, for it then can find no other resource but in the dexterity of its manoeuvres, unless it is favoured by the wind, or any oversight of the enemy. 3. The disabled ships of the weather line must tack, to avoid falling into the enemy’s fleet; and if they are much shattered, they may be altogether separated, particularly if they are in the rear of the line. - - The defects of the Lee Line are, 1. It cannot decide the time and distance of the battle, which may commence before it is sufficiently formed, and it will perhaps be attacked by an ene- my who bears away upon it in regular order. 2. It suffers much inconvenience from the fire and smoke of the weather-Fine, as remarked in the advantages of the weather line (1.) It cannot easily break the enemy's line with its fire-ships, which are slowly and with difficulty conveyed to windward. On the contrary, the fire-ships of the weather line have a considerable advantage (3.) The line of a fleet, which has abundance of capital ships, need not be so much enclosed as that of an enemy who has fewer. An open line will, on many occasions, work more easily than one which is more enclosed ; and if it is less numerous, the movements thereof are more expeditious, the signals better attended to, the general orders more exactly observed, and the ships less liable to be separated. Hence it will be less embar- rassed by a change of wind, and order will be sooner re- established. A less numerous line will more readily approach or escape from an enemy or an hostile shore, and finally, when cruising in a smaller space, it will not be so much contracted. It must be remarked, that the admiral's ship attentively pre- serves her station in the centre of the line ; for if the com- mander in chief should give way to the caprice or inattention of any of those under his direction, it would introduce an endless disorder into his squadron. LINE, is also the general appellation of a number of small ropes in a ship, as Concluding LINE, a small rope which is hitched to the middle of every step of a stern ladder.—Deep Sea Line, a long line, mark- ed at every five-fathoms with small strands of line knotted. It is used with the deep-sea lead.—Fishing LINE, a particular kind of line generally used for fishing.—Hand LINE, a line about 20 fathoms long, marked with black leather, white rag, and red bunten, at different distances. It is made fast to a hand lead, and used to determine the depth of water in going in or out of harbour, river, channel, &g.—Hauling LINE, any rope let down out of a top, &c. to haul up some light body by hand.—Knave LINE, a rope fastened to the cross-trees, under the main or fore top, whence it comes down by the ties to the ram-head, and there it is reeved through a piece of wood of about two feet long, and so is brought to the ship's side, and there hauled up taught to the rails.-Life-LINE, a rope occasionally extended in several situations for persons to lay hold of, to prevent their falling.—Naval-LINE, a rope depending from the heads of the main and fore masts, and fastened to the middle of the truss, to keep it up whilst the yard is being swayed up. Spilling Lines, ropes fixed occasionally to the square-sails, particularly the main and fore courses of a ship in tempestuous weather, for reefing or furling them more conveniently; they are received through blocks upon the yard, whence leading round the sail, they are fastened behind to the yard, so that the sail is by their efforts very closely confined.—White-LINE, implies that which has not been tarred, in contradistinction to tarred line.—Mar-LINE, is a particular kind of small line, composed of two strands very little twisted; there is both tarred and white mar-line. LINEN, in Commerce, a well-known kind of cloth, chiefly made of flax. Linen was not worn by the Jews, Greeks, or Romans, as any part of their ordinary dress. Under-tunics of a finer texture supplied the place of shirts: hence the occasion for frequent bathing. Alexander Severus was the first em- peror who wore a shirt: but the use of so necessary a garment did not become common fill long after him. In Egypt, indeed, the linen manufacture appears to have been very early ; for even in Joseph’s time it had risen to a considerable height. From the Egyptians the knowledge of it proceeded probably to the Greeks, and from them to the Romans. Even at this day, the flax is imported among us from the eastern nations; the western kind being merely a degenerate species of it. In order to succeed in the linen manufacture, one set of people should be confined to the ploughing and preparing the soil, sowing and covering the seed, to the weeding, pulling, rip- pling, and taking care of the new seed, and watering and dress- ing the flax till it is lodged at home: others should be concerned in the drying, breaking, scutching, and hackling the flax, to fit it for the spinners; and others in spinning and reeling it, to fit it for the weaver: others should be concerned in taking due care of the weaving, bleaching, beetling, and finishing the cloth for the market. It is reasonable to believe, that if these several branches of the manufacture were carried on by distinct dealers in Scotland and Ireland, where our home-made linens are manufactured, the several parts would be better executed, and the whole would be afforded cheaper, and with greater profit. Staining of Linen.—Linen receives a black colour with much more difficulty than woollen or cotton. The black struck on linen with common vitriol and galls, or logwood, is very perish- able, and soon washes out. Instead of vitriol, a solution of iron in sour strong beer is to be made use of. This is well known to all the calico-printers; and by the use of this, which they call their iron-liquor, and madder root, are the blacks and purples made, which we see on the common printed linens. The method of making this iron-liquor is as follows: A quan- tity of iron is put into the sour strong beer; and to promote the dissolution of the metal, the whole is occasionally well stirred, the liquor occasionally drawn off, and the rust beat from the iron, after which the liquor is poured over again. A. length of time is required to make the impregnation perfect; the solution being reckoned unfit for use, till it has stood at least a twelvemonth. This solution stains the linen of a yel- low, and different shades of buff-colour; and is the only known substance by which these colours can be fixed in linen. The cloth stained deep with the iron-liquor, and afterwards boiled with madder, without any other addition, becomes of the dark colour which we see on printed linens and cottons; which, if not a perfect black, has a very near resemblance to it. Others are stained paler, with the same liquor diluted with water, and come out purple. Linen may also be stained of a durable purple by means of a solution of gold in aqua regia. The solution for this purpose should be as fully saturated as pos- sible; it should be diluted with three times its quantity of water; and if the colour is required deep, the piece, when dry, must be repeatedly moistened with it. The colour does not take place till a considerable time, sometimes several days, after the liquor has been applied: to hasten its appearance, the subject should be exposed to the sun and free air, and occasionally removed to a moist place, or moistened with water. When solution of gold in aqua regia is soaked up in lineni cloths, the metal may be recovered by drying and burning them. Fossile LINEN, is a kind of amianthus, which consists of flexible, parallel, soft fibres, and which has been celebrated for the use to which it has been applied, of being woven, and forming an incombustible cloth. Paper also, and wicks for lamps, have been made of it. - LINIMENT, in Pharmacy, a composition of a consistence somewhat thinner than any unguent, and thicker than an oil. LINSTOCK, a staff about three feet long, having a sharp point at one end, and a sort of fork or crotch in the other; the latter serves to contain a lighted match, and by the former, the linstock is occasionally stuck in the deckin an upright position. It is frequently used in small vessels in an engagement, where there is commonly one fixed between every two guns, by which the match is always kept dry and ready for firing. s L I S. L I T 581 Diction ARY OF MECHANICAL scIENCE. LINT, in Surgery, is the scrapings of fine linen, used by 'surgeons in dressing wounds. It is made into various forms, which acquire different names according to the difference of the figures. Lint, made up in an oval or orbicular form, is called a pledgit ; if in a cylindrical form, or in shape of a date | or olive stone, it is called a dossil. These different forms of lint are required for many purposes; as, 1. To stop blood in fresh wounds, by filling them up with dry lint before the appli- cation of a bandage : though, if scraped lint be not at hand, a piece of fine linen may be torn into small rags, and applied in the same manner. In very large haemorrhages, the lint or rags should be first dipped in some styptic liquor, as alcohol, or oil of turpentine; or sprinkled with some styptic powder. 2. To agglutinate or heal wounds; to which end, lint is very service- able, if spread with some digestive ointment, balsam, or vul- nerary liquor. 3. In drying up wounds and ulcers, and for- warding the formation of a cicatrix. . 4. In keeping the lips of wounds at a proper distance, that they may not bastily unite before the bottom is well digested and healed. , 5. They are highly necessary to preserve wounds from the injuries of the air. — Surgeons of former ages used compresses of Sponge, wool, feathers, or cotton, linen being less plentiful than in later times: but lint is far preferable to all these, and is at present universally used. . LINUM Usit Atissl Mum. FLAx, or Lint Seed.—Is grown for the purpose of making cloth, and has been considered a very profitable crop. The culture and management is similar to that of hemp, and the seeds are in great demand for pressing: Lintseed oil, which it produces, is much used by painters, and is the only vegetable oil that is found fit for such purposes in general. The seeds are of several uses to the farmer ; a tea is made of it, and mixed with skimmed milk, for fattening house- lambs and calves. Oxen are often fattened on the seed itself; but the cakes, after the oil is expressed, are a very common and most excellent article for fattening both black cattle and sheep. These are sold at from £10 to £16 per thousand. It will require three bushels of flax-seed for one acre, as it must be sown thick on the land. Linseed cake has been used also for manure; and I have seen fine crops of turnips, where it has been powdered, and sown in the drills with the seed. * LIQUORICE. The glycyrrhiza, or common liquorice shrub, has a long, thick, creeping root, striking several feet deep into the ground; an upright, firm, herbaceous, annual stalk, three or four feet high, garnished with winged leaves, of four or five pair of oval lobes, terminated by an odd one ; and from the axillas, erect spikes of pale blue flowers in July, succeeded by short smooth pods. The root of this plant is the useful part, being replete with a sweet, balsamic, pectoral juice, which is either extracted, or the wood sold in substance. It is much used in all compositions for coughs, and disorders of the stomach; but by far the greatest quantity is used by brewers. The common liquorice is cultivated in most countries of Europe, for the sake of its root; but in Spain and Italy, and particularly in Sicily and Calabria, it makes a considerable article of commerce with this country. Liquorice also grows : in great abundance in the Levant; and vast quantities of it are consumed there, in making a decoction which is drunk cold in the summer, in the manner of sherbet. To prepare liquorice, the roots are boiled a long time in water, till the fluid has got a deep yellow tincture; and the water at length, eva- porated till the remains acquire a consistency, when they are formed into sticks, which are packed up with bay leaves, in the same order as we receive them. The boiling requires the utmost care and precaution, as the juice takes an unpleasant smell and flavour, if burnt in the least degree. - - LIST, Civil, in the British polity. The expenses defrayed by the civil list are those that in any shape relate to civil government; as, the expenses of the household; all salaries to officers of state, to the judges, and every one of the king's ser- wants; the appointments of foreign ambassadors; the main- tenance of the queen and royal family; the king’s private expenses, or privy purse; and other very numerous out-goings, as secret-service money, pensions, and other bounties; which sometimes have so far exceeded the revenues appointed for that purpose, that application has been made to parliament to discharge the debts contracted on the civil list. 60. - - To List, or ENList Soldiers, to retain and enroll men as soldiers, either as volunteers, or by a kind of compulsion. Per- sons listed, must be carried within four days, but not sooner than twenty-four hours after, before the next justice of peace of any county, riding, city, or place, or chief magistrate of any city or town corporate, (not being an officer in the army,) and if, before such justice or magistrate, they dissent from such enlisting, and return the enlisting money, and also twenty shillings in lieu of all charges expended on them, they are to be discharged. But persons refusing or neglecting to return and pay such money within twenty-four hours, shall be deemed as duly listed as if they had assented thereto before the proper magistrate; and they shall, in that case, be obliged to take the oath, or, upon refusal, they shall be confined by the officer who listed them till they do take it. & - LIST, in Commerce, the border of cloth or stuff; serving not only to shew their quality, but to preserve them from being torn in the operations of fulling, dyeing, &c. List is used on various occasions; but chiefly by gardeners, for securing their wall trees. - . - . . . . . List, in Architecture, a little square moulding, otherwise called a fillet, listel, &c. See ARCHITECTURE. - * LIST, is also used to signify the enclosed field or ground wherein the ancient knights held their justs and tournaments. It was so called, as being hemmed round with pales, barriers, or stakes, as with a list. Some of these were donble; one for each cavalier; which kept them apart, so that they could not coine nearer each other than a spear’s length. See Just, To URNAMENT, DUEL, &c. * * * LIST, implies an inclination to one side, as, The ship has a list to port, i. e. is depressed more in the water on that side. LITANY, a solemn, form of supplication to God, in which the priest utters some things fit to be prayed for, and the peo- ple join in their intercession, saying, “We beseech thee to hear us good Lord,” &c. The word comes from the Greek “supplication.” Before the last review of the common prayer, the litany was a distinct service by itself, and used some time after the morning prayer was over; at present it is made one office with the morning service, being ordered to be read after the third collect for grace, instead of the inter- cessional prayers in the daily service. * LITHOGRAPHY. Lithography, or the art of taking im- pressions from drawings or writings made on stone, is quite a modern invention. It, unlike letter-press or copperplate print- ing, which are altogether mechanical processes, depends en- tirely upon chemical principles, and has therefore been called in Germany, chemical printing. The principles on which it is founded are, first, the quality which a compact granular lime- stone has of imbibing grease or moisture; and secondly, the decided antipathy of grease and water for each other. A draw- ing is made on the stone, either with ink or with a crayon of a greasy composition ; it is then washed over with water, which sinks into those portions of the stone which are untouched with the grease of the drawing. A cylindrical roller, charged with printing ink, is then passed all over the stone ; and, while the drawing receives the ink, the rest of the stone is preserved from it by the water, on account of the greasy nature of the ink. . . . . . . . This useful art was invented by mere accident. Alois Sene- felder, the son of a performer at the theatre royal, Munich, a student of jurisprudence in the university of Ingoldstadt, after the death of his father, took likewise to the stage; but, being unsuccessful in his pursuit of it, he afterwards became an author. Poverty was indeed, in him, the mother of invention; for being too poor to publish his works, he tried various plans, with copperplates and compositions, as substitutes for letter- press, that he might thus become his own printer. In the course of his experiments he found that a composition of soap, wax, and lamp black, formed an excellent ink for writing with on plates; as, when dry, it became firm and hard, and resisted aquafortis. He wanted facility, however, in writing backwards on the plates, and that he might practise this at less expense, he procured some pieces of Kilheim stone, as a cheap material, on which, after polishing their surfaces, he might practise. Having been desired by his mother to take a list of some linen about to be sent to be washed, and having no paper at hand, 582 L I T L I T DictionARY of MECHANICAL scIENCE. he wrote it out on a piece of stone with his composition. When he was afterwards about to efface his writing, it occurred to him that impressions might be obtained from it; and, after he had eaten away the stone with an acid, for about the hun- dredth part of an inch, he found that he could easily take suc- cessive impressions. It appeared to him, that the new mode of printing was of very considerable importance ; and he there- fore, through great difficulties, persevered in improving it, and in attempting its application to practical purposes. He soon found that it was not necessary to have the letters raised above the stone; but that the chemical properties which keep grease and water so effectually separate from each other, were quite sufficient for his purpose. He afterwards bestowed much labour and assiduity in constructing the proper press, and other apparatus, for printing. The first essays to print for publication, were some pieces of music executed in 1796; af- terwards he attempted drawings and writings. He still, how- ever, found great difficulty in writing backwards, and this led him to think of the process of transfer; and the use of dry soap, which was found to leave permanent traces which would give impressions, naturally led to the mode of chalk drawings. In 1799, after having made many improvements, Mr. Sene- felder obtained a patent privilege for Bavaria. He then made known his invention to Mr. Andre, of Offenbach, with whom he entered into partnership, and proposed to establish printing offices, and take ont patents at Tondon, Paris, and Vienna. In order to establish presses in England, Senefelder came to Lon- don with a brother of Mr. Andre's ; and most of the English artists made trial of the art. drawing and printing, caused constant failures, and the artists in succession abandoned it. . An attempt was made, in 1800, by Senefelder alone, to estab- lish presses in Vienna; and after great difficulty, a patent was obtained ; but bad management, and some unfortunate circum- stances, prevented its succeeding, and he returned to Munich in 1806, leaving the establishment which he had formed in other hands. In 1806, Mr. Mitterer, professor of drawing in the public school at Munich, practised lithography to obtain copies for his pupils. He is said to have invented the chalk composition in its present form, or at least to have improved it greatly. The practice of the art now began rapidly to extend and improve, more particularly at Munich, where several establishments were formed for the purpose of applying it to the fine arts, as well as for printing writings and official forms for the different departments of the government. In 1809, Senefelder was ap- pointed inspector of the royal lithographic establishment at Munich, from printing from stone a complete map and survey of Bavaria; since which period he has devoted his time to expe- riments, and to writing the history of his invention. In England it can hardly be said to have been entirely given up from the time of its first introduction in 1800, yet it was little practised or thought of after 1806, until it was revived in 1817. Since this, it has been more generally attended to, and some of the establishments having now become well acquainted with the process of printing, specimens have been produced in England equal to those of any other country. In France but little was done in lithography till 1815, when it was established in Paris, by Lasteyrie ; and, being taken up by good artists, it soon at- tained great excellence. About the same time it extended to Russia and other parts of Europe. The Stones, and the manner in which they are prepared to receive the Drawings.-The stone most used in England is found at Corstan, near Bath. . It is one of the white lias beds, but not so fine in grain, nor so close in texture, as the German stone, and, therefore, far inferior. But it is good for transfers, and does tolerably well for ink drawings or writings. Another stone is also used, found near Stony Stratford; but it is of a brownish gray tint, and too dark in colour to shew the effect of | the drawing with sufficient clearness. All calcareous stones can be used in lithography, because they will all imbibe grease | fire, adding small portions of the black at a time, and stirring them well together. When the ink is made, and cold, its frac- ture should have the appearance of Indian ink, though in its and moisture, but those are best adapted to it which are very compact, of a fine equal grain, and free from veins, or imbed- ded fossils or crystals. The stones first used were obtained But, unfortunately, it was not then fully understood; and the difference of materials of Ger- many and those of England, used both for the purposes of |thod is the best; After the process just described has been gone from the quarries of Solenhofen, near Pappenheim, in Bavaria, and none have ever been obtained to equal them. . In France, stones have been found near Chateauroux, of a similar colour to these, and even harder, and of a finer grain; but full of large spots of a softer nature. - In order to sustain the pressure used in taking impressions, a stone 12 inches square, must be 13 inch thick; and the thick- ness must increase with the size of the stone. The stones are first sawn to a proper size, and are then ground smooth and level by rubbing two of them, face to face, with water and sand. They must be very carefully examined with a straight-edge, to ascertain that they are perfectly level in all directions. This applies only to the side which is afterwards to receive the drawing, as the natural division of the stone is sufficiently true for the back. } When the stones have been thus ground perfectly level, they are well washed, to free them from any of the coarser grains of sand which may have been used in smoothing them; and they are then placed on a board over a trough, and again they are rubbed face to face with sand and water, though the sand now used must be of a much finer texture than the sand previously used. The greatest care must be taken to have the sand suffi- ciently fine; and for this purpose it must be sifted through a small close sieve, as a single grain of sand, of a coarser texture than the rest, will scratch the stone, and these scratches will afterwards appear in the impressions taken from the stone. When the stones have been rendered sufficiently fine, and their grain sufficiently gradoth, thcy must then be carefully washed and then wiped dry with a clean soft cloth. This is the plan adopted to prepare the stones for chalk drawings; but to prepare them for ink drawings or writings, the following me- through, the stones are well washed, to get rid of the sand, and they are then rubbed two together, face to face, with powdered pumice-stone and water. After they are made perfectly smooth, they are again washed and wiped dry, and are then separately polished with a large piece of pumice-stone. - In order to clean the Stones after they have been fully used.— Sand is strewed over the surface, and it is sprinkled with water, and rubbed with another stone, until the writing or drawing upon it has completely disappeared. It must then be washed with aquafortis diluted in twenty times its bulk of water; and the stone is then prepared for a new drawing or writing by being rubbed with fine sand or pumice stone as before. The longer drawings remain on stones, the deeper the ink or the chalk pe- netrates into their substance, and consequently the more of the stone must be ground away to remove them; this is also more necessary with ink drawings than with chalk ones, because ink penetrates much deeper into the stone than chalk. The stones being thus prepared, it is necessary now to enter upon the substances which are used for drawing or writing upon them. These are Lithographic Ink, or Chalk. A great many different receipts have been given for making Lithographic ink, and out of these we shall give the best. Two kinds of ink are necessary—that for writing on the stones, and that for making transfers. The best composition which we have seen for ink for writing is the following; $ Composition of Lithographic Ink for Drawing on the Stone. —Two ounces of the tallow of candles; two ounces virgin wax; two ounces shell lac ; two ounces common soap ; and of lamp black nearly about a twentieth part of the whole. These materials must be prepared in an iron saucepan having a cover; the wax and tallow are first put in, and are heated till they take fire; while they are burning, the soap is thrown in, in separate pieces one at a time, care being taken that one be melted before another is thrown in. When the whole soap has been added, the composition must be allowed to burn until it has lost about a third of its quantity. After this, the shell lac is added; and, as soon as it is melted, the flame must be extin- guished. After being allowed to cool, it should now dissolve, (though it will do so but slowly,) by rubbing it in warm water. The lamp black, which must be of the finest quality, is now to be mixed with it, which is done while it is melted over a slow I, I. T. L I Tº 583 DICTIONARY OF MECHANICAL SCIENCE. substance it is softer. After being completely melted and mixed with the black, it should be run on a marble slab, and a heavy weight placed above it, in order to press it. After very careful management, the ink will be sometimes found defective ; this, however, must proceed from something being wrong with the ingredients, or the manner of their pre- paration; but, as it is impossible to prevent imperfections, it will be as well to mention a few of those which most commonly occur, with the remedies to be used to remove them. - Defects of the Ink, and Remedies to be used.—1st. The ink will at times be found insoluble. The proper remedy, in this case, is to add more soap, in the same manner it was first added. Although the ingredients are to be melted over a fire, in order to have the additional soap mixed with them, they must not be allowed to take fire, as was the case when the soap was first added. 2d. It is sometimes too soft, and attaches itself to the fingers. When this happens, it must again be put into the saucepan, and burned till it gets to a proper consistence. 3d. We find a defect of almost all inks to be, that, some time after dissolving them in water, they become thick and slimy, and require a continual addition of water before we are enabled to draw with it. This is solely owing to its not being sufficiently burnt; and of course the only remedy is, as in the former case, to burn it more. 4th. If the ink is not compact, but full of bubbles, it has been cast too hot on the marble slab. It must therefore be re-melted, cast again when it is less hot, and a heavier weight must be placed upon it. 5th. On other occasions the ink will be found to have no tenacity, and seem to be composed of scorias. When this is the case, it has been either too much burnt, or contains too much black; in either case, add equal portions of wax and soap, and melt it again over a slow fire. - The only other ink we have mentioned, as being necessary in lithographic drawing or printing, is - w Ink for making Transfers.—This ink is composed of the very same materials as the ink for writing or drawing ; but they must be less burned. It will thus be softer, and it must also be afterwards melted and mixed with a little more wax and thick varnish, such as those we shall mention when we come to speak of the printing ink. Lithographic Chalk.-Besides the inks, we have already men- tioned that chalks are used for drawing. Good lithographic chalk ought to have all the qualities of a good drawing crayon. It should be even in texture, and should carry a good point. The best proportions for its composition are the following: an ounce and a half of common soap; tallow two ounces; virgin wax two and a half ounces; shell lac one ounce. The rest of the process is the same as in making the ink. Less black should be mixed with the chalk than with the ink, its only use being to colour the drawing, that the artist may see the lines he traces. When the whole is well mixed, it should be poured into a mould, and very.strongly pressed, to prevent any bubbles which would make the texture irregular. Now that we have described the preparation of the stone, and of the inks and * necessary for drawing, we must next proceed to notice the Mode of Drawing.—Previous to drawing or writing, the stone must be well wiped with a clean dry'cloth. The ink is rubbed with warm water like Indian ink, and must be used on the polished stone, while the chalk, which would not hold upon it, must be used on the ground stone. A gradation of tints, in drawing with the ink, can easily be obtained by merely varying the thickness of the line, and the distance at which they are placed apart; for the line traced by the ink being sound and unbroken throughout, receives the printing all over. It is thus plain that no advantage can be obtained by diluting the ink for the purpose of varying the tints of the lines; and the great object of the artist ought therefore to be, to have his ink of the proper consistency, which will stand best throughout the pro- cess of printing. A consistency a little stronger than common writing ink will be sufficient for this purpose. . When the chalk is to be used, the ground stone must be cleaned of all dust, and it is then drawn upon with the chalk in the same manner as crayons are used on paper. It is pro- per that the strength of the tint which is wished should be given at once, as the surface of the stone is altered by receiving the chalk, and it will not receive new lines equally well; and the strength of the tint will be regulated by the pressuré of the hand. Nothing but practice ever gives the necessary command of the material, which undoubtedly does not work quite like the common crayon, there being great difficulty in keeping a good point. There is likewise considerable trouble in obtaining the finer tints sound in the impression; and in order to obtain the lighter tints properly, it will be necessary to put the chalk in a rest, as the metal port crayon is too heavy to draw them, even although there is no pressure of the hand used. Several pieces of chalk should be prepared, to use in succession, as the warmth of the hand softens it. It is useful to cut the chalk to the form of a wedge rather than a point, as it is less likely to bend in that form. Small portions sometimes break off during the drawing; these must be carefully removed with a brush. We now proceed to describe the press and rollers used, with the maner of printing. That given in the engravings is certainly the best we have ever seen, although there are different forms ID UISC, Fig. 1, is a side elevation of the press, with the scraper partly down. Fig. 2, a cross section through the middle. Fig. 3, a horizontal plan of the upper part. Fig. 4, detail of the man- ner in which the scraper is held down during the impression. & #* : *. 3. - Fig.1. y: ${2 § #|: o 60 c , jv : go tº º C * CL as as * * * * * * * * * ***** * * * * * 7- P.- | R. A. A RT | ** - # R. ; F. W o -Ö Fig. 5, end elevation of the press. Fig. 6, to explain the man- ner in which the centre of motion of the scraper is raised and lowered. - - 584. L I T L I T DICTIONARY OF MECHANICAL SCIENCE. & The press consists of a strong frame, having on the upper part a platten or bed, a, to receive the stone, and which is moved along grooves in the upper part of the frame by means of a star-wheel b, to the axis of which is fixed a cylinder c. On this cylinder the straps d, d, are gathered, which work over the pulleys e, fixed to the bed. When the stone is placed on the bed, and ready for the impression, the frisket, or cover, f, of the hed, is brought down from the position marked by the dotted outline in fig. 1, and shut over the stone, as shewn in the same figure. This cover consists of a strong piece of calf's skin, stretched by screws with nuts and hooks, which catch hold of an iron rod sewed along one end of the skin. The other end of it is fixed to the opposite end of the frame. (See fig. 3.) The cover is fixed to the bed by hinges, g, which can be screwed at different heights, according to the thickness of the stones. When the cover is opened, it rests against the frame h, which can be adjusted to different heights. (See figs. 1 and 5.) The cross piece i, having the scraper k fixed in it, is now brought down, and the catches l lock into the upper part of the piece n, sliding between the grooved upright m. This is shewn more in detail in fig. 4; the upper part where the catches lock, is of iron, and has a joint and handle to pull it out when the scraper is to be unlocked. A spring o, keeps it generally in an upright position to be ready to hold the catches !, l. When the scraper is locked down, the printer sets his foët on the treadle p, of the lever, which presses the scraper with great power on the stone. The pressure is by a double lever, having a connecting rod q, which can be adjusted so as to bring the upper arm r nearer to the treadle, when an increase of pressure is required, or a thinner stone is placed on the bed, which makes it necessary to bring the scraper lower down. The arm r passes through an iron frame on the sliding piece n, and thus brings it down when the treadle is depressed. The hook s holds down the treadle during the impression. The star wheel b is now turned round, and by this motion the bed is drawn under the scraper, and the impression is taken. The bed passes over a roller t, which is placed with its centre directly under the scraper. (See fig. 2.) As the stones are not always of the same thickness, the scraper must be brought to different heights. Fig. 6, shews an adjusting screw for the purpose of regulating the end farthest from the catches, there being a sliding piece between the grooved uprights w, in which the centre is fixed, on which the cross piece i turns. The iron v, fig. 2, stops the cross piece and scraper from falling back. When the bed has been drawn out, the printer releases the treadle, which is raised up by the balance weight w, and the scraper being unlocked and thrown back, the bed is drawn to its first position by the weight a. • As the surface of the stone is not always quite parallel to the bed, a simple contrivance has been adopted, to allow a self- adjustment of the scraper, which is allowed to turn on the centre, and pressed down by a spring acting on each end, but yielding if necessary at either. It is shewn by the dotted lines in fig. 2. The screw y presses the scraper lower, or raises it, if required. The scrapers are made of beech wood. The Roller.—The roller for inking the drawing is of the form represented in fig. 7. The length may vary, but it ought to be full four inches in diameter. It is covered with flannel, rolled tightly three or four c0A, ACTO times round, and nailed at the ends. It Fig. 7. is then covered with a stretched calf- - Gº skin, fitting quite tight. The seam must The ends of the leather be made neatly with the boot-maker's closing stitch. are gathered with a string, and tied round the projecting ends of the roller. Loose handles, A, A, made of thick leather, are put on these ends when it is used. The leather must be put on the roller with the rough side outwards. - Printing Ink.-The printing ink is composed, as other print- ing inks are, of oil, warnish, and very fine lamp-black, well mixed together. To prepare the varnish, a saucepan is about half filled with pure linseed oil, and heated over a fire till it ignites from the flame of a piece of burning paper. It should then be allowed to burn till it is reduced to the degree required; and if, during the operation, there appears danger of its boiling over, it must be immediately taken off the fire, and the cover, which ought to fit quite close on the saucepan, must be put on to extinguish the flame. This is to prevent acci- dents; and the operator cannot be sufficiently cautioned against the danger attending the burning of the warnish, which ought never to be performed in a room with a boarded floor, or indeed in any part of a house. Wet sacks are the best things. to put out the flame in case of accident. * . . . Several inks must be prepared, differing in the degree of viscidity, or thickness of the warnish from which they are made, and the quantity of black mixed with them. The longer the oil is burned, the thicker the varnish becomes. The thinnest warnish is burned till it has lost nearly one-fourth of its volume; the next, till it is reduced one-third; the thickest, till it is reduced one-half. - • . These directions are to be considered as very general ones; and the state of the varnish is best judged of during the burn- ing, by taking out some with a spoon, and letting a drop fall on a cold earthenware plate, and trying its degree of viscidity with the finger. The thinnest sort should be like common honey, the other should draw out in strings, which will be longer as the varnish is thicker. The thickest will draw out in strings two or three feet long. It is quite essential to have the oil pure, and the saucepan perfectly clean, and to keep the varnish in clean close jars in a cool place. It is best not to make the var- nish long before it is wanted; for if any decomposition takes place in it, the drawing will be spoiled by the printing ink. The black is mixed with the varnish on a grinding stone with a muller, in small successive quantities, care being taken that the first portion of black is equally mixed with the varnish before a second is added. In the thickest inks this requires considerable labour. By mixing the varnishes together, any degree of stiffness of the ink may be obtained; and by putting more or less black, its thickness is regulated. - The printer must always have by him several small pots, each containing a different printing ink, to be used as occasion requires. A small quantity. not more than the size of a hazel nut, should be used at a time, for it is desirable to charge the roller with as small a quantity as possible. It must be worked well on the colour table with the roller in all directions, that it may be equally distributed all over the roller. Ink drawings are gene- rally printed with a stiffer ink than chalk drawings. - Preparation of the Stone for Printing.—The drawing being finished on the stone as before described, is sent to the litho- graphic printer, on whose knowledge of his art the success of the impressions entirely depends. The first process is to etch the drawing, as it is called. This is done by placing the stone obliquely on one edge over a trough, and pouring over it very dilute nitric acid. It is poured on the upper part of the stone, and runs down all over the surface. The stone is then turned, and placed on the opposite edge, and the etching water, being collected from the trough, is again poured over it in the same manner. The degree of strength, which is little more than one per cent. of acid, should be such as to produce a very slight effervescence; after the etching water has lain on the stone for a second or two, its strength must vary according to the heat of the atmosphere, and the degree of fineness of the drawing. It is desirable to pass the etching water two or three times over the darkest parts of the drawing, as they require more etching than the lighter tints. Some stones also, and different chalks, require different degrees of strength of the acid, and experience alone can guide the lithographer in his practice on this point. Chalk drawings require weaker acid than the ink. . . . The stone is now carefully washed, by pouring clean rain water over it, and afterwards with gum water: and, when not too wet, the roller, charged with printing ink, is rolled; over it in both directions—sideways, and from top to bottom—till the drawing takes the ink. It is then well covered over with a so- lution of gum-arabic in water, of about the consistency of oil. This is allowed to dry, and preserves the drawing from any alteration, as the lines cannot spread, in consequence of the pores of the stone being filled with the gum. After the etching it is desirable to leave the stone for a day, and best not to leave it more than a week before it is printed from. In some establishments a few proofs are taken immediately after the drawing is etched, but it is better not to do so. L I T L I T 585 DICTIONARY of MECHANICAL scIENCE. * The operation of the etching requires great nicety, and must be done quickly. If the drawing is etched too strongly, the fine tints disappear; if too weak, the printing ink mixes with the darker parts, and the drawing runs into blots. A soft stone requires weaker acid than a hard one, if they are equally pure in quality. The differences in the composition of the stone also ‘require differences in the strength of the etching water, so that no strict rules can be given. The effect of the etching is, first, to take away the alkali mixed with the drawing chalk or ink, which would make the drawing liable to be affected by the wa- ter; and, secondly, to make the stone refuse more decidedly to take any grease. The gum assists in this latter purpose, and is quite essential to the perfect preparation of the surface of the Stone. Printing.—When the intention is to print from the stone, it is placed upon the platten or bed of the press, and a proper sized scraper for the printing is adjusted to the surface of the stone. Rain water is then sprinkled over the gum on the stone, which being dissolved gradually, and a wet sponge passed lightly over it all, the printer works the ink which is on the co- lour table placed beside him, with the roller, in all directions, until it is equally and thinly spread all over the roller. The roller is then passed over the whole stone, care being taken that the whole drawing receives a due portion of the ink, and this must be done by giving the roller an equal motion and pressure, which will of course require to be increased, if it is perceived that the drawing does not receive the ink readily. When the drawing is first used, it will not receive the ink so readily as it will afterwards do; and it is frequently necessary to wet the stone, and roll it several times, before it will take the ink easily. When the drawing once takes the ink readily, care must be taken not to wet the stone too much. Indeed, the less dampness now the better, provided there is sufficient to prevent the stone from taking the ink where there is no drawing. After the drawing is thus rolled in, the sheet of paper is placed on the stone, and the impression taken in the manner described in the account of the Press. When, after the impression, the paper is taken up, the stone appears dry, the moisture having been imbibed by the paper; it must, therefore, be wetted with a sponge, and again rolled in with ink, the roller having been well worked on the colour-table before being applied. During the printing, some gum must always remain on the stone, although it will not be visible, otherwise the ink will be received on the stone as well as on the drawing, and the draw-, ing spoiled. So that if by too much wetting, or by rubbing too hard with the sponge, the gum is entirely removed, some fresh gum water must be laid on. If the stone has in the first instance been laid by with too small a quantity of gum, and the ink stains the stone on being first applied to it, gum-water must be used to damp the stone, instead of pure water. Some- times, however, this may arise from the printing ink being too thin, as will afterwards appear. If some spots on the stone take the printing ink, notwithstanding the above precautions, some strong acid must be applied to them with a brush, and, after this is washed off, a little gum-water is dropped on the place. A steel point is here frequently necessary to take off the spots of ink. - The edges of the stone are very apt to soil, and generally require to be washed with an old sponge or rag after the roll- ing in. They must also frequently have an application of acid and gum, and sometimes must be rubbed with pumice stone. If an ink is too thin, and formed of a varnish not suffi- ciently burned, it will soil the stone, notwithstanding the pro- per precautions are taken of wetting the stone, and preparing it, properly with acid and gum ; and if on the other hand the ink is too thick, it will tear the lighter tints of the chalk from the stone, and thus destroy the drawing. The consideration of these circumstances leads at once to the Principles of the Printing.—These accidents arise at the ex- treme points of the scale at which the printing inks can be used, for it is evident that the only inks which can be employed are those which are between these points; that is, thicker than that which soils the stone, and at the same time thinner than that which takes up the drawing. Lithographers are some- times unable to print in very hot weather, the reason of which may be deduced from the above. Any increase of temperature will diminish the consistency of the printing ink; the stone will therefore soil with an ink which could be safely used at a lower temperature ; hence a stiffer ink must be used. Now, if the temperature should increase so much that the stone will soil with any ink at all less, thick than that which will take up the drawing, it is evident that the printing must cease till a cooler temperature can be obtained ; for as the drawing chalk is affect- ed equally with the printing ink, the same ink will tear up the drawing at the different degrees of temperature. This, though it sometimes occurs, is a rare case; but it shews that it is desirable to draw with a chalk or ink of less fatness in summer than in winter; and also, that if the printing room is in winter artificially heated, pains should be taken to regulate the heat as equally as possible. - Other Difficulties in Printing, not referable to the above general principle.—If the pressure of the scraper is too weak, the ink will not be given off to the paper in the impression, although the drawing has been properly charged with it. Defects will also appear from the scraper being notched, or not correctly adjusted, or from any unevenness in the leather or paper. After printing a considerable number of impressions, it some- times happens that the drawing takes the ink in dark spots in different parts. This arises from the printing ink becoming too strongly united with the chalk or ink of the drawing, and, if the printing is continued, the drawing will be spoiled. The reason of this is easily ascertained. The printing ink readily unites with the drawing, and, being of a thinner consistency, it will, by repeated applications, accumulate on the lines of the drawing, soften them, and make them spread. In this case it is necessary to stop the printing, and let the stone rest for a day or two, for the drawing to recover its proper degree of hard- ness. If the drawing should run smutty from any of the causes before enumerated, the following \ Mixture for Cleaning the Drawing while Printing must be used. Take equal parts of water, spirits of turpentine, and oil of olives, and shake them well together in a glass vial, until the mixture froths; wet the stone, and throw this froth upon it, and rub it gently with a soft sponge. The printing ink will be dis- solved, and the whole drawing also will disappear, though, on a close examination, it can be distinguished in faint white lines. On rolling it again with printing ink, the drawing will gradually reappear as clear as at first. Bleached Paper unfit for Lithographic Printing.—Accidents sometimes occur in the printing from the qualities of the paper. If the paper have been made from rags which have been bleach- ed with oxymuriatic acid, the drawing will be incurably spoiled after thirty impressions. Chinese paper has sometimes a strong taste of alum; this is so fatal as sometimes to spoil the drawing after the first impression. When the stone is to be laid by after printing, in order that it may be used again at a future period, the drawing must be rolled in with a . . Preserving Ink,-as the printing inks would, when dry, be- come so hard, that the drawing would not take fresh printing ink freely. The following is the composition of the preserving ink. Two parts of thick varnish of linseed oil, four parts of tallow ; one part of Venetian turpentine, and one part of wax. These must be melted together, then four parts of lamp black, very carefully and gradually mixed with it, and it must be preserved for use in a close tin box. Very good effects are produced in lithographic prints, by - Printing from two or more Stones—with different coloured inks. This is managed by preparing a composition of two parts of wax, one of soap, and a little vermilion. Melt them in a saucepan, and cast them into sticks. This must be rubbed up with a little water, to the thickness of cream, and applied to the surface of a polished stone. An impression is taken in the common way from a drawing, and applied to a stone, prepared in this manner, and passed through the press, taking care to mark, by means of this impression, two points in the margin corresponding on each of the stones. The artist having thus, on the second stone, an impression from the first drawing to guide him, scrapes away the parts which he wishes to remain white in the finished impression. The stone must now be etched with acid stronger than the common, etching water, having one part of acid to twenty of water. The whole is then washed off with turpentine. This planis generally used to print a mid- 7 K. 586 L. O. A Li T * DictionARY of MECHANICAL science. die tint from the second stone. The black impression being given from the first stone, a flat transparent brownish tint is given from the second, and the white lights are where the paper is left untouched. The dots are necessary to regulate the pla- cing of the paper on the corresponding parts of the two stones. The paper for lithographic printing should not be so damp as for copperplate printing. - - LITHOMARGE, in Mineralogy, is a species of the clay * genus, and divided, by Werner and others, into two sub- - . - | cavaliers, at their tournaments, distinguished themselves by LITHONTRIPTICS, an epithet for medicines that are sup- Though the different species, viz. the friable and the indurated. posed to break the stone in the bladder. § stones that are generated in the human bladder require differ- ent solvents when out of the body; and though art has not yet afforded a medicine, which, when injected into the bladder, will, without injury thereto, dissolve the stone therein lodged ; it cannot thence be concluded, that there are no lithontriptic medicines. It may be here observed, that one solvent affects one subject, but has no effect on another; so a solvent may yet be met with, that will destroy the stone, and not hurt the Human body. The water in which the boiled white of an egg dissolves will liquefy myrrh, but may be put into the human eye without causing any uneasiness. Soap ley, taken at first in small doses, in broth that is freed from all its fat, succeeds in most cases which require an alkaline solvent. The patient may begin with twenty drops, and gradually increase the dose as he is able; and by repeating it three times a day for six, eight, or twelve months, the wished-for effects often follow. LITMUS, or LACMUs, in the Arts, is a blue pigment, formed from archil. bruised by grinding. The mixture having cooled, and the fluid suffered to evaporate, becomes a mass of the consistence of a paste, which is laid on boards to dry in square lumps. It is only used in miniature paintings, and cannot be well depended on, because the least approach of acid changes it instantly and fly. . . . LITTER, a kind of vehicle borne upon shafts; anciently esteemed the most easy and genteel way of carriage. Du Cange derives the word from the barbarous Latin lecteria, “straw or bedding for beasts.” Others will rather have it come from lectus, “bed,” there being ordinarily a quilt and a pillow to a litter, in the same manner as to a bed. Pliny calls the litter the traveller's chamber; it was much in use among the Romans, among whom it was borne by slaves kept for that purpose ; as it still continues to be in the East, where it is called a palanquin. The Roman lectica, made to be borne by four men, was called tetraphorum; that borne by six, herapho- rum; and that borne by eight, octaphorum. The invention of litters, according to Cicero, was owing to the kings of Bithy- nia: in the time of Tiberius they were become very frequent at Rome, as appears from Seneca; and even slaves themselves were borne in them, though never by more than two persons, whereas men of quality had six or eight. - LITTER, also denotes a parcel of dry straw put on the floor of a horse's stall, for him to lie down and rest upon. When a horse comes tired into a stable, fresh litter has the virtue of making him stale immediately. This is known to be of very great advantage to a horse in a tired state; and when the litter is old and dirty, it never has any such effect upon him. If the owners knew how refreshing it is for a horse to discharge his urine on his return from labour, they would be more care- ful of giving them all means and occasions of it than they are. This staling, after fatigue, prevents those obstructions in the neck of the bladder, or urinary passages, to which horses are too subject. LITURGY, denotes all the ceremonies in general belonging to divine service. In a more restrained signification, liturgy is used among the Romanists to signify the mass; and among us, the common prayer. All who have written liturgies agree, that, in the primitive days, divine service was exceedingly sim- ple, only clogged with a very few ceremonies, and consisting of but a small number of prayers; but, by degrees, they in- creased the number of external ceremonies, and added new It is brought from Holland at a cheap rate: but may be prepared by adding quicklime and putrefied urine, or spirit of wine distilled from lime, to the archil, previously from blue to red. The best litmus is very apt to change prayers, to make the office look more awful and venerable to the people. At length things were carried to such a pitch, that a regulation became necessary; and it was found proper to put the service, and the manner of performing it, into writing; and this was what they called a Liturgy. * . . LIVERY, in matters of dress and equipage, a certain colour and form of dress, by which noblemen and gentlemen choose to distinguish their servants. Liveries are usually taken from fancy, or continued in families by succession. The ancient wearing the liveries of their mistresses: thus people of quality make their domestics wear their livery. - * LIVERY MEN of Londo N, are a number of men chosen from among the freemen of each company. Out of this body the common-council, sheriff, and other superior officers for the government of the city, are elected ; and they alone have the privilege of giving their votes for members of parliament, from which the rest of the citizens are excluded. LIXIVIATION, is the application of water to bodies, for the purpose of dissolving the saline part: by pouring off the liquid after lixiviation, and then evaporating, the salt is obtained. LOAD, or Lode, in Mining, a word, used especially in the tin mines, for any regular vein or course, whether metallic or not; but most commonly, load means a metallic vein. When the substances forming these loads are reducible to metal, the loads are by the English miners said to be alive; otherwise they are termed dead loads. In Cornwall and Devonshire, the loads chiefly hold their course from eastward to westward, though in other parts of England they frequently run from north to south. - LOADING AND UNLoADING MACHINE, an invention of G. Davis, of Windsor, for removing ponderous substances to or from waggons, &c. with safety and convenience. In the figure given of this portable machine, (see the Plate,) A is the winch turning the bar B, on which are two endless screws, or worms, C C, that work in the toothed wheels D. D. These wheels are fixed to the barrels EE, round which the ropes FF coil, wind up, or let out the same occasionally : the ropes pass over the pulleys G. G.; are brought round; and their ends being furnish- ed with hooks for that purpose, are hitched into staples fixed to the front of the cart, or other carriage. Within these ropes, the load H is placed on a common step-ladder I, that forms an inclined plane, up which, by turning the winch, the ropes are wound upon the barrels; and, thus the load is raised into the carriage. KK, the frame, intended to shew the part of the cart, or other carriage, on which the machine is to be occasion- ally placed. The whole of the barrels and cogged wheels are contained in an iron box L; the sides of which are represented in the plate as taken off, in order that the arrangement of the different parts may be better conceived. The pulleys on the stage (GG) may, in most cases, be affixed to the machine itself; which is adapted to every direction, and will suit carriages of every construction. The model corresponding to the present engraving is made on the scale of about four inches to a foot; and the inventor states, that it will raise upwards of five cwt. He is therefore confident that this machine, when constructed of its intended size, will be capable of loading a ton weight by one man only ; and that, even upon this enlarged plan, it does not exceed 112lb. in weight. The Society of Arts in 1797 awarded 40 guineas to Mr. Davis for this useful invention. LOADING of a GUN, is the act of charging it, or the charge itself. - LOADSMAN, a pilot or person that conducts into or out of harbours. - . LOADSTONE, See the article DIPPING Needle. LOAMS, in Natural History, are defined to be earths com- posed of dissimilar particles, stiff, dense, hard, and rough to the touch ; not easily broken while moist, readily diffusible in water, and composed of sand and a tough viscid clay. Of these loams, some are whitish, and others brown and yellow. LOANS, in Political Economy, sums of money borrowed from individuals or public bodies, for the service of the state: they are either compulsory, in which case they may be more properly termed requisitions: or voluntary, which is the only mode that can be frequently resorted to with advantage. Loans are sometimes furnished by public companies as a consider- L ‘O Č L O C 587 'DICTIONARY OF MECHANICAL SCIENCE. ation for péculiar privileges: but are much more commonly advanced by individuals on a certain interest being allowed either for a term of years, or until the principal shall be repaid; the capital stock being transferable. - - * LOBE, in Anatomy, any fleshy protuberant part, as the lobes of the lungs, the lobes of the ears, &c. LOBELIA, Cardinal flower, a genus of plants belonging to the syngenesia class, and in the general method ranking under the 29th order, Campanaceae. LOBBY, in Architecture, is a small hall, or waiting room: it is also an entrance into a principal apartment, where there is a considerable space between that and a portico or vestibule, and the length or dimensions will not allow it to be considered as a vestibule or an anti-room. LOCK, a well known instrument used for fastening doors, chests, &c. generally opened by a key. The lock is reckoned the master piece in smithery ; a great deal of art and delicacy being required in contriving and varying the wards, springs, bolts, &c. and adjusting them to the places where they are to be used, and to the several occasions of using them. From the various structure of locks, accommodated to their different in- tentions, they acquire various names. Those placed on outer doors are called stock locks ; those on chamber-doors, spring- locks; those on trunks, trunk-locks, padlocks, &c.—Of these the spring-lock is the most considerable, both for its frequency and the curiosity of its structure. Its principal parts are, the main-plate, the copper-plate, and the pin-hole : to the main- plate belong the key-hole, top-hook, cross-wards, bolt-toe, or bolt-knab, draw-back-spring tumbler, pin of the tumbler, and the staples; to the cover-plate belong the pin, main-ward, cross ward, step-ward, or dap-ward; to the pin hole belong the hook- ward, main cross-ward, shank, the pot or bread bow-ward, and bit. , The principle on which all locks depend is the application of a lever to an interior bolt, by means of a communication from without ; so that, by means of the latter, the lever acts upon the bolt, and moves it in such a manner as to secure the lid or door from being opened by any pull or push from without. The security of locks in general therefore depends on the number of impediments we can interpose betwixt the lever (the key) and the bolt which secures the door; and these impediments are well known by the name of wards, the number and intricacy of which alone are supposed to distinguish a good lock from a bad one. If these wards, however, do not in an effectual manner preclude the access of all other instruments besides the proper key, it is still possible for a mechanic of equal skill with the lockmaker to open it without the key, and thus to elude the Iabour of the other. The excellence of locks consists in the security they afford; and as numberless schemes are continu- ally brought forward by designing men, to elude every contri- vance of the most ingenious mechanics, the invention of a du- rable lock, so constructed as to render it impossible for any person to open it without its proper key, has ever been an object of considerable importance. r In the year 1784 the Society for the Encouragement of Arts, &c. conferred their silver medal on Mr. Taylor, of Petworth, for his improvement on the latch or spring-bolts of common locks. This is effected by simply reversing the tumbler, so that its curved side acts against two stubs fixed on the tail of the latch, and thrusts back the latter with ease ; whether the knob be turned to the right or to the left, when the lock is opened. Mr. Taylor has also behind the tail of the latch fixed a guide containing a groove, in which runs a small friction-wheel, that serves to keep the latch in its direct situation, and at the same time to diminish its friction: the arms of his tumbler are some- what contracted, in order that the latch or spring-bolt may move with great facility. By this construction, the parts of the tumbler and latch, which are in contact, move in a line, so that they pass over the greatest space, and under the smallest angle; and the lock itself may be constantly used for several years with- * out requiring the application of oil. , Various patents have been obtained for the construction of locks/so as to prevent the pos- sibility of picking them: the principal of these is Bramah's. Chubb's Patent Detector Lock.-The following drawing will give our readers a full insight into the peculiarities of Chubb's celebrated Detector Lock. ...A.A. a, the bolt; b, the Square pin of the bolt; c e the detector moving on the centre d, f the detector spring ; g four tumblers moving separately on the centre h, shewn lifted by the key to the exact position, for the Square pin b of the bolt to pass in unlocking. Should one or more of the tumblers be lifted by a pick, or false key, in the least degree beyond their present position, the detector cc, being thus overlifted, will, by the angle of the spring f pressing on the opposite side of the angle of the detector, force its hook into the notch a of the bolt, and be firmly held so, until disen- gaged by the regulating slide, Kh; in which case, by the introduction of the key, the tumblers are lifted to the regulating º & - . | w § § - *@º *=::::::= sº =<= º: $º B. : . combination, and admit the stud n affixed to the regulating slide, to enter the several grooves in the ends of them; the bevelled end h of this slide, by the same movement, pressing against the hook of the detector, disengages it from the notch a of the bolt. The merits of this lock, as stated by the ingenious inventor, are, that it possesses, in a much higher degree than any other, the four principal requisites of a good lock, viz. security, sim- plicity, strength, and durability. Its security is increased beyond calculation, by an improvement which not only renders it impossible to be picked or opened by any false instruments, but also detects the first attempt to open it, thereby prevent- ing those repeated efforts to which even the best locks hitherto invented are exposed. The instant that one or more of the tumblers are lifted beyond the place where the bolt is at liberty to pass, it overlifts the detector, which then hooks the tail of the bolt, prevents it from passing, and thus gives incalculable additional security, (as well as immediate notice, the first time the true key is put into it to open it, that an attempt has been made to pick it,) and renders all farther attempts useless, it being impossible to discover the first combination, in order to disengage the detector, or the second, in order to remove the bolt. Nothing, in short, but the true key can either release the detector from its grasp on the bolt, or open the lock. The simplicity of its construction, and strength of its parts, are such, that no false key or other instrument introduced into it for the purpose of opening it, can (without great violence) injure it. The keys are small and portable, particularly those for iron doors. With respect to its durability, it is not liable to be injured by constant use in any length of time; this has been ascertained by an iron-rim lock having been attached to a steam-engine in the dock yard, Portsmouth, (to try the effect of friction,) by which it was locked and unlocked upwards of four hundred and sixty thousand times, without receiving the least injury. The honourable Navy Board lately supplied a considerable number of Chubb’s patent detector locks for the use of the Ports- mouth dock yard, and being informed that there was a convict on board one of the prison ships at that port, who was noto- rious for picking locks, (being by profession a lock-maker, and who has, till recently, for several years been chiefly employed in 588 L O C L O C DICTIONARY OF MECHANICAL SCIENCE. picking and repairing locks in London,) Mr. C. requested the favour of commissioner, the honourable Sir George Grey, to send for this man, that he might exercise his skill in attempt-. ing to pick his lock; and the commissioner having been pleased to acquiesce in this request, the man was sent for accordingly, and one of Chubb's patent locks was submitted to his inspec- tion, at the storekeeper's office, in the presence of several of the principal officers; when, after a careful examination, he said, “he thought he could pick or open it with false instru- ments.” He was therefore furnished with files, and all the tools he stated to be necessary to prepare the instruments for his purpose; and was directed to give notice to the storekeeper when he should be ready to make the trial, for the promotion of which a reward of five pounds was promised him if he suc- ceeded. In about three weeks after this time, he sent to say that he was ready; and a time being fixed for the purpose, he commenced his operations in endeavouring to pick one of the locks, in the presence of the principal officers of the dockyard; but he could not succeed.—Mech. Mag. 1824. Bellamy's Improved Common Lock.-The annexed figures exhibit an ingenious N and ' useful improve- ment on the common lock, invented by an industrious and hard- working mechanic, of the name of Bellamy, resident in Lambeth. No. 1, is the securer; 2, the bolt; 3, spring for sending the securer down again ; 4 4, Sup- porters; 5, the hoister; 6, wards for key ; 7, the key, which should have five wards, one after the other, as close as they can be made. - Ellington's Patent Lock.-Description of the lock:—A is the brass plate of the lock; B the pin which goes into the pipe of the key, having at the lower part a circular piece of brass, which revolves round it; this has four slits to receive the corresponding parts of the key; C the tumbler; E the spring to keep down the bolt; F the pin to secure the bolt in its place; G the staple (double link); H the cap; I the key; K K the screw holes of the cap; J the bush, or pipe. |L iſ A. | #|| | | ſiliſii, | The advantages of this lock will be obvious from the descrip- tion. Instead of a great heavy key, with a large bit of iron, (called a bit,) being required, as in locks of the kind now in vogue, you have a key so small, that it may be attached to the watch-chain: nor is there any possibility of the bit breaking in the lock, as is sometimes the case, and valuable articles of furniture being thus destroyed or damaged. In the next place, there are no wards to break or bend; the brass circular revolv. ing talent answers the place of the wards, shooting the bolt as it goes round. The slits answer the purpose of keeping out any false pipe, or skeleton-key, which might be introduced. The cap of the lock is made with a large bush, similar to Mr. Bramah's patent, so as to leave no possibility of a picker entering. The price of Mr. Bramah's lock is 3s.6d. ; but the utmost which can, with propriety, be charged for Mr. Elling- ton's is only 1s. 6d. while it is equally, if not more, secure. Mr. E., warrants, beyond all possibility of being picked, all of his make. - - Fairbank's Lock, in place of the feather or Scotch spring for forcing out the bolt, is fitted with a spiral or worm spring, by which means the bolts or latches are moved with greater ease than by any other sort of springs; the spiral springs, whether constructed to exert their force by expansion or contraction, are, the inventor thinks, more durable, and less likely to get out of order, than any other description of springs hitherto applied to locks or latches. , This lock is represented in the figure. a is the bolt; b the tumbler; c the spiral spring acting on the tumbler; d a tooth in the tumbler, which falls into one of two notches in the bolt; e the pivot stud on which the tumbler moves, square at bottom, in order to guide the bolt; f the bridge and wards; g a small stud supporting the spiral spring; h a catch bolt, which may be forced out by an- other spiral spring i, placed in the fork (or in any other sort of recess); h a follow, with two wings acting against the tails of the bolt. On introducing the key into this lock, and turning it round, it raises the tumbler b, and by releasing the tooth a from the notch, allows the bolt a to be slidden out; after the key has passed the tumbler, the spiral spring acting against the tail of the tumbler, causes the tooth to fall into the second notch, by which | the bolt is held fast until the tumbler is again raised by the key. The follow k is turned in the common manner, by a pair of knobs, with a spindle, when it draws back the bolt, which is again pushed forward by the spiral spring.—Mech. Mag. Lock. Security.--The following method of securing ſocks ap- peared in one of the numbers of the Mechanical Magazine, but whether it is original or not we have no means of judging. A, is a piece of round iron, with a cross piece at one end, form- ed as a screw at the other. B is a stout circular piece of iron or brass, having at one end a square shoulder of half or three- quarters of an inch in thickness; close to this shoulder, on the circular part, a screw is to he formed of three or four turns; and close to the other extremity of this piece, B, a circular hole is made quite through. C is a circular or oval plate of iron or brass, of the same thickness as the square shoulder piece of B, but of greater diameter; in the centre of this piece C, a Square hole is to be cut through, to fit easily over the shoulder of piece B. D. is a small piece of iron of half an inch projection, fixed in, and just beneath the centre of one of the Squares of the aperture in C. B is a hollow iron or brass circular tube, hav- L O C 589 DICTIONARY OF MECHANICAL scIENCE. **- : **. ing a circular shoulder, which shoulder must be rather larger than the shoulder of B. Within this piece, E, must be formed at the shoulder end, a corresponding screw to the one on B. At the other extremity of E a corresponding circular hole is to be made through, to come in contact with the circular hole in B. . The mode in which this additional lock security will operate is as follows:—The piece A is to screw into the centre of piece B, on the side where the shoulder is, which is to be bored through as far as the circular hole in B, with a corresponding screw of A. Then ascertain the thickness of the door to which you mean to apply this machinery; lengthen or shorten the piece A by means of the screw ; introduce your cross-piece, A. into the key-hole, or, as may be, through to the inner side of the door: then turn the cross piece transverse to the key-hole, leaving the shoulder of B as close in contact as possible with the key-hole. * - - - © ... The piece C is then to be slid on the shoulder of B, being made sufficiently large to cover the key-hole. The projecting piece D going into the lower part of the key-hole, keeps the transverse position of A from being displaced. E is then to be screwed over B, tight against the plate C, the shoulder of E being rather larger than that of B, so that the shoulder of E may press against that of C. - - The two circular corresponding holes in B and E coming in unison, you pass through the bar of your combination lock, or common padlock, as you please, and your key-hole is then se- cure from a picklock, or introduction of skeleton or false keys. By making the circular holes longitudinally, you may apply two or more combinations or padlocks, in case you wish to make any room or chest a deposit for joint security. . Another great advantage to a door that opens externally, having a key- hole and no lock on it, is that, by having a cross piece, as A, with one side of the cross of a proper length, so as to bear against the inner side of the door-post, your door may be se- curely fastened. - - To travellers, and persons travelling about for pleasure, who too often suſfer from the insecurity of locks, this apparatus seems particularly worthy of attention. No injury is done by apply- ing it, and it is of such light weight, as to be portable in the pocket. This invention professes to come from a lieutenant of the royal navy; we should have been happy to have added his name, did we know it. Description of an Instrument for Securing Door and other Locks.—The object of the instrument about to be described, and which is here represented, is to prevent the introduction of a skeleton key, or similar implement, into a lock, for the pur- pose of opening it. Its parts are as follow : a a is a circular plate of stout iron, suf- ficiently large to cover the key-hole; b b is a cylindrical pipe, which passes perpendicularly through a hole in the centre of the plate a a, and is strongly fastened to it by means of the projecting shoulder e e : did is a round bar, en- closed in the pipe b b : c is a small nut riveted to the end of d d, for the purpose of turning it; m n are two small pieces of iron attached trans- versely to the cylindri- cal pipe b b, and its en- closed bar dd respec- tively. When the in- strument is being intro- . . . duced into the key-hole, these pieces coincide, or rest longitudi- nally upon each other (as in fig. 1); but when passed through the lock, they are turned at right angles to each other, by the thumb-nut, or bottom already mentioned, and are, in this situa- tion, firmly inserted cross-wise into each other, by means of a these pieces when secured in their place; fis a cylindrical aperture, part of which is in the wire a, and part in the 'shoulder e. To this aperture is accurately fitted the transverse bar of a strong combination lock, so complex as to be totally inacces- sible to any person except the possessor of its key. While the bars at m, m, remain across each other, the instrument cannot be removed out of its place; and hence the security of this lock, for strong boxes, counting-houses, and places of safety.— Mech. Mag. 1824. - . . . . ' New Double Door Spring.—The annexed are drawings of a double door spring, invented by Mr. James White, of Laystall- Street, which may be fixed either at top or bottom of the door, and is so contrived that the power of the spring is greatest when the door is shut. It is not liable to get out of repair, and the expense is moderate, not exceeding twenty-two shillings. In fig.1, the dotted lines a a, shew part of the door shut; b, the centre on which the door turns: c, an arm carrying a fric- tion roller (d, fig. 3); e e, two levers on which the spring ff Fig.1. ſº Fig.2. ; :...? f"h; N d - * * * - º . Rºº. I. º: , sº . *- sº a ºil...º-ºttºll|A Wº - º * * * * * * * * * * * * * * * * * * * * * * * * * * * * * . .” & “ . . i 5. * - - -- * * * * * - - - | º :=2#E } | --~~~ ||||||| EZF P- %5:###################### #ºſſ-Fºſſijägå º %ZZZZZZ/Z. IIIºlº, Z4% * Zuzz/E e J 3% ºf £ 772 . Z, - - acts, and thereby holds the door shut ; g, a stop, which pre- vents the levers being pushed farther than to the shut door. When the door is shut, the spring facts with half its power on the arm c, at full length, but when the door is open as in fig. 2, it acts with about one-sixth of its power on the arm c, in a di- rection which reduces its effect on the door also about one- sixth, whereby the action on the door, when open, is one- eighteenth of the power which holds it shut ; but admitting the strength of the spring to have increased by one-half, there then remains a reduction of power equal to one-twelfth of the origi- nal quantity. These numbers, however, depend on the propor- tion of the levers, and on the part where the spring acts. - In figs. 1, and 2, the upper plate by which it is screwed to the floor, is removed, to shew the parts; its place is shewn by the dotted lines and holes h h h h. Fig. 3, a section of the box; a a, part of the door shut; ii, a brass shoe screwed on the door; the centre b is fitted into a square hole, and secured by a screw nut k; l, a screw which hooks on to the spring f, to regulate its power by turning the nut m. Mech. Mag. 1824. Lock, or Weir, the general names for all those works of wood or stone made to confine or raise the water of a river: the banks also which are made to divert the course of a river are called by these names in some places. But the term Lock is more particularly appropriated to express a kind of canal enclosed between two gates; the upper called by workmen the sluige- gate, and the lower called the flood-gate. These serve in arti- ficial navigations to confine the water, and render the passage of boats easy both in passing up and down the stream. . . . LOCKER, a kind of box or chest made along the side of a º G e ship, to put or stow any thing in.—Shot Lockers, strong frames, small groove, cut in each of them; m (fig. 2) is a front view of | of plank near the pump-well in the hold, in which the shot are 7 L. * 590 L. O. G. -, LOG, a machine used to measure the rate of a ship’s velocity through the water. For this purpose, there are several various inventions, but the one most generally used is the following, called the common log. It is a piece of thin board, forming the quadrant of a circle of about six inches radius, and balanced by a small plate of lead mailed on the circular part, so as to swim perpendicular in the water, with the greater part immers- ed. The log line is fastened to the log by means of two legs, one of which is knotted through a hole at one corner, while the other is attached to a pin fixed in a hole at the other corner, so as to draw out occasionally. The log line being divided into certain spaces, which are in proportion to an equal number of geographical miles, as a half, or quarter minute, is to an hour of time, is wound about a reel. The whole is employed to measure the ship's head-way in the following manner: the reel being held by one man, and the half- minute glass by another, the mate of the watch fixes the pin, and throws the log over the stern, which, swimming perpendi- cularly, feels an immediate resistance, and is considered as fixed, the line being slackened over the stern, to prevent the pin coming out. The knots are measured from a mark on the line, at the distance of twelve or fifteen fathoms from the log; the glass is therefore turned at the instant that the mark passes over the stern; and as soon as the sand in the glass has run out, the line is stopped; the water then being on the log dis- lodges the pin, so that the board now presenting only its edge to the water, is easily drawn aboard. The number of knots and fathoms which had run off at the expiration of the glass, deter- mines the ship's velocity. The half-minute glass and divisions on the line should be frequently measured, to determine any variation in either of them, and to make allowance accordingly. If the glass runs thirty seconds, the distance between the knots should be 50 feet. When it runs more or less, it should, therefore, be corrected by the following analogy. As 30 is to 50, so is the number of seconds of the glass to the distance be- tween the knots upon the line. As the heat or moisture of the weather has often a considerable effect on the glass, so as to make it run slower or faster, it should be frequently tried by the vibration of a pendulum. As many accidents attend a ship during a day’s sailing, such as the variableness of winds, the different quantity of sail carried, &c. it will be necessary to heave the log at every alteration; but if none of these alterations be perceptible, yet it ought to be constantly heaved. In ships of war and the East Indiamen, it is usual to heave the log once every hour, and in all other vessels once in two hours; and if at any time of the watch the wind has increased or abated in the intervals, so as to affect the ship's velocity, the officer generally makes a suitable allowance for it at the close of the watch. +. t The inventor of this simple but valuable device is not known, and no mention of it occurs till the year 1607, in an East India voyage published by Purchas. Since that time the term has become quite familiar, both among our own countrymen and foreigners, and there can be no room for apprehension, that a contrivance so useful will ever share the fate of its author. - ... Log BoARD, two boards shutting together like a book, and divided into several columns, containing the hours of the day and night, the direction of the winds, and the course of the ship, with all the material occurences that happen during the twenty- four hours, or from noon to noon, together with the latitude by observation. From this table the offiders work the ship's way, and compile their journals. The whole being written with chalk, is rubbed out every day at noon. Log-Book, a book into which the contents of the log-board is daily transcribed at noon, together with every circumstance deserving notice that may happen to the ship, or within her cognizance, either at sea, or in a harbour, &c. The intermediate divisions or watches of a log-book, containing four hours each, are usually signed by the commanding officer thereof, in ships of war or East Indiamen. • Log line, the line which is fastened to the log. - LOGARITHMS, (the ratio of numbers,) are the indices of the ratio of numbers to one another, or they are a series of numbers in arithmetical progression, answering to another series of numbers in geometrical progression; or, which con- DICTIONARY OF MEGHANICAL SCIENCE. # L O G veys a still more simple and unembarrassed idea of these num- bers, they are indices of the powers of a certain radix, which, when involved to the power denoted by the index, is equal to the given number; thus, if r * = a, r v = b, r * = c, then is r the logarithm of a, y the logarithm of b, 2 the logarithm of c, &c. where r is called the radix of the system, and may be assumed any number at pleasure, unity only excepted. These numbers are of the greatest possible use in almost all arithmetical and trigonometrical operations, because by the help of them multi- plication is performed by addition, division by subtraction, involution by multiplication, and evolution by division. To multiply two numbers together, we must take the sum of their logarithms; to divide one number by another, we must sub- tract the logarithm of the divisor from the logarithm of the dividend. To involve a number to any power, we must multiply the logarithm of the number by the index of the power. And to extract the root of a number, we divide the logarithm of the number by the index of the power whose root is to be extracted; but each of these rules require some additional illustration, which may be seen in any table of logarithms; but before we pro- ceed any farther, let us attend to the history of this brilliant dis- covery. These properties of the indices of numbers were taken notice of by Stifelius, and even by Archimedes in his work on the numbering of the sands; but it is to Baren Napier, of Mer- chiston, in Scotland, that we are indebted for the happy idea of applying such numbers to the purposes of arithmetical and trigonometrical calculation, which first appeared in his “Miri- sici Logarithmorum Canonis Descriptio,” published at Edin- burgh in 1614. But of all those who assisted in the construc- tion of logarithmic tables, Briggs is the most conspicuous; it was he who first suggested our present system, the advantages of which are incalculably greater than those first constructed by Napier, at the same time that he laboured more than any one in the construction of them. In the present state of ana- lysis, many comparatively short methods may be employed for this purpose, that were unknown to the early writers, and for want of which the labour attending the first computation was exceedingly great, notwithstanding they had certain means of abridging the operation in particular cases; a minute and interesting account of which, with an explanation of their several modifications, is given by Dr. Hutton in the introduc- tion to his Mathematical Tables, to which work the reader is referred for every information on this subject. The publi- cations relating to logarithms are so numerous, that we can only find room to mention a small portion of them; but as it is useful to know which are reputed the best authors, and parti- cularly the best editions of the same authors, we shall subjoin the following list, which may be considered as containing the most respectable and accurate works of this kind: The first Canon of Logarithms for natural Numbers, from 1 to 20000, and from 90000 to 101000, was constructed and published in 1624, by Briggs, with the approbation of the inventor, Lord Napier. Briggs' Logarithms, with their difference to 10 places of figures; as also the logarithmic sines, tangents, &c., by George Miller, London, 1631. Sherwin's Mathematical Tables, published in 8vo. London, 1704, form the most complete collec- tion of any we have yet noticed; containing, besides the loga- rithms of all numbers from 1 to 101000, the sines, tangents; secants, &c. versed sines, both natural and logarithmic, to every minute of the quadrant. The first edition was printed in 1706, but the third, published in 1742, as revised by Gardiner, is considered as superior to any other. The fifth and last edi- tion, published in 1717, is so incorrect that no dependence can be placed upon it. Dr. Hutton's Mathematical Tables con- tain the common hyperbolic and logistic logarithms ; also sines, tangents, secants, and versed sines, both natural and logarithmic ; together with several other tables useful in ma- thematical calculations; to which is prefixed, a history of the discoveries and writings of the most celebrated authors on this subject. This work was first published in 1785, since which time it has passed through five editions, and is much esteemed for its accuracy. Taylor's Tables of Logarithmic Sines and Tangents, to every second of the quadrant; to which is pre- fixed, a Table of Logarithms from 1 to 100000, is a very valuable work, and has a useful introduction, composed by the late astronomer royal, Dr. Maskelyne, . . . . . . - - - L. O. G. . L. O. G. DICTIONARY OF MECHANICAL SCIENCE. 591. LOGARITHMIC or Logistic SPIRAL, is a curve having similar properties to the above, but differently constructed; thus, divide the quadrant of a circle into - any number of equal parts in the points A, B, D, &c.; and from the radii CA, C B, C D, &c, cut off CA, C b, C d, &c. continually proportional, then the curve passing through the points A, b, d, &c. will be the logarithmic spiral. Hence the several areas are as the logarithms of the ordinates; and hence the denomi- nation of the curve. LOGIC, or the Art of Reasoning, is intended to guide and assist the intellectual powers of man in the investigation of truth, and in the communication of it to others. This science is not, therefore, a mere explanation of scholastic and barba- rous phrases; nor a set of rules to teach the art of disputation; but it traces the progress of the human understanding in the acquisition of knowledge, and thus suggests the best methods of avoiding error, and discovering truth. The operations of the mind in acquiring and communicating knowledge, are, “ Perception,” “Judgment,” “Reasoning,” and “Disposition;” and into these parts logic is divided. Perception, or conception, is the attention which the mind gives to impressions made upon it, and the results of percep- tion are sensations and ideas. Example. We can conceive of a horse, a tree ; of motion, time, &c. which will produce cor- responding sensations and ideas. Judgment, is the operation of the mind by which we join two or more ideas together by an affirmation or negation. Sen- tences, called propositions, are the effect of judgment. Example. “This tree is high :” here are two ideas, viz. one of a tree, and another of its height: the sentence is complete and affirmative. “That house is not large:” this is a negative proposition. Both are the effect of judgment. In Reasoning, we determine the relation between two ideas, by comparing them with a third idea, called the middle term. Example. If we affirm, that “God will make a difference between the evil and good,” it is the result of reasoning, by which we suppose, that “A just being will make a difference between the good and evil ;”—and that “God is a just being.” • The result of reasoning is an inference; and the expression of an act of reasoning is called a syllogism. Example: A Creator is to be worshipped. God is a Creator; Therefore, God is to be worshipped. Here is a syllogism; and the inference is, that “God is to be worshipped.” - Disposition is the proper arranging of our ideas upon any subject, so as to assist our own and others’ conception and memory. The result of disposition is method. - Of Ideas. There are two modes of perception, viz. sensation and reflection. Sensation is the perception of an object by the organs of sense, which are five, seeing, hearing, tasting, smelling, and touching. By sight we acquire ideas of light and dark- mess, and colours; by hearing, of sounds, &c. Reflection is the perception, intellectually, of the operations of our minds, and by this we gain sensations and ideas. Illustration: Reflection presupposes sensation, as its im- pressions are only the effect of the various powers of the understanding, employed, about perceptions already in the mind. t - A Sensation is the impression made upon the mind by an object actually present; an idea is a revived impression in the absence of the object. Illustration: The grand source and inlet of knowledge is sensation, which comprehends all the notices conveyed into the mind by impulses made upon the organs of sense. Ideas are either simple or complex. Simple Ideas are those that exist in the mind under one uniform appearance, without variety or composition, as a colour, or sound. - . . " . . Compler Ideas are those that may be divided into two or more simple ideas, as a square, a triangle, &c. Simple ideas enter the mind only by inlets appropriated to this purpose, and it cannot refuse to receive them. Simple ideas are incapable of change; but they gradually wear out of the mind, unless revived by the same means by. which they were originally acquired. Example :- We, soon forget the countenance of a man whom we have seen but once. Simple ideas are capable of combinations in an indefinite variety of forms, and are the materials of all our knowledge. Complea: Ideas, or collections of objects, are produced by Composition, Abstraction, and Comparison. By Composition we add or augment, as, a waggon and horses. By Abstraction. we select certain properties of an object, and overlook others, as when we contemplate a triangle, a square. And by Com- parison, we have ideas of greater and less, &c. - Complex ideas are either representations of objects really existing, or collections made at the pleasure of the mind. The objects really existing are either substances, or modes. Substances are beings or things, subsisting by themselves; as steel, brass, &c. Modes are the properties of substances, and dependent upon them for support; as hardness, softness, brightness, extension, &c. Our ideas of substances extend only to their properties." Modes are either essential or accidental: an essential mode is that which is necessary to its existence, as solidity and round- ness are essential to a bowl ; an accidental mode is that which is not necessary to the existence of the subject, as roundness is only an accidental mode of a stone; the bowl cannot exist as a bowl without roundness, but a stone may. Of Words. Words are articulate sounds used as the signs of ideas. The connexion between words and ideas is perfectly arbitrary; but, by frequent use, a term becomes so strongly associated with an idea, that it never fails to suggest it. The use of words is to record our own trains of ideas, and to com- municate our thoughts to others: our ideas are recorded by being clothed in words, and communicated in writing. We communicate our thoughts to one another by a tacit agreement to annex the same ideas to the same words. Language may be resolved into nouns and verbs, with their abbreviations. Nouns, express the names of things, and are either substan- tives, which are the things spoken of, or adjectives, which denote the qualities or circuimstances belonging to them. Verbs express modes of existence, either simply, as “to be ;” or existence in an active state, as “to run,” “to walk,” &c.; or existence in a passive state, as “to be elected.” Indeclinable particles are abbreviations of nouns and verbs, invented for the greater expedition of communicating our thoughts; thus if signifies give ; and signifies add, being the imperatives of the verbs. Simple words are the elements of language, as simple ideas are of all knowledge. Of Definition. Definition is an enumeration of the chief simple ideas of which a compound idea consists, in order to ascertain or explain its nature and character. - Definitions are either nominal, of the name, or real, of the thing. - ºominal definition is an enumeration of certain marks or characters, sufficient to distinguish the thing defined from any other. Such is the definition of a square, as a figure contain- ing four equal sides, and four right angles. A definition of a thing includes an enumeration of the prin- cipal attributes of the thing, in order to explain its nature; thus an isosceles triangle is a figure having the angles at the base equal. • Definitions are either accurate or inaccurate; the first are strictly definitions, the second only descriptions. The rules for a good definition are, 1. It should be clear, and more obvious than the thing defined. 2. It should agree to all the species included under the same idea. It must be peculiar to the thing defined. 4. It should be short. 5. Neither the thing defined, nor a mere synonymous name, should make any part of the definition. Judgment. When two ideas are compared, they either con- cur, as, snow and whiteness, or coincide, as God and Creator; they do not concur, as vice and usefulness; or they do not coincide, as man and eagle. This concurrence and coincidence of ideas, or the want of it, we call judgment, which is, in fact a third or intervening idea. 592 L O G Lo G. DICTIONARY - OF MECHANICAL SCIENCE. The sources of judgment are consciousness, sense, intuition, and testimony. * * . . . . . . . . Consciousness is the mind's perception of its own existence, faculties, and operations. properties, and powers of external objects; and the founda- tions of natural knowledge. Intuition is the instant perception of the relation between two ideas, as “the whole is greater than any of its parts, and equal to all its parts.” . - Testimony is the criterion of facts, which do not fall imme- diately under our own observation. of testimony is the proof of facts, which having happened in past-times, or in distant places, have not fallen under the cog- nizance of the senses. Testimony must be true when the relater is not himself deceived, and does not intend to impose on others. - - . A judgment or mental proposition, is that union or separa- tion of the ideas which is the result of the act of judging, and it may exist without any connexion with words. A proposition is a judgment clothed in words, and it con- sists of three parts, the subject, the predicate, and copula. | Example 1. Virtue is excellent. 2. Gold and silver are the most precious metals. Here virtue in the one example, and gold and silver in the other, are subjects; the verbs is and are the copulae; excellent and most precious metals the predicates. The subject of a proposition is the idea concerning which something is affirmed or denied ; the predicate is the idea united to, or separated from the subject; the copula is the sign which represents the union or the separation of the subject of the predicate. Illustration: In the proposition, “Wisdom is the principal thing.” Wisdom is the subject, is the copula, and principal thing the predicate. The several parts of a proposition are not always distinctly expressed, but are always understood; thus, “I walk,” “ he pleads,” may be resolved into “I am walking,” “he is plead- ing. r - Propositions may be divided into affirmative and negative ; the affirmative connects the predicate with the subject, as “f gold is heavy;” the negative separates the predicate from the subject, as “Man is not perfect.” Propositions are universal and particular; in an universal proposition, the predicate ex- tends to the whole subject, as “ All men are mortal.” “No man is truly happy.” The signs of an universal proposition are usually the words all, every, no, none. In a particular pro- position, the predicate is limited to a part of the subject, as * Some people are good.” “Many philosophers have been deceived.” The signs of particular propositions are, some, many, few, &c. Propositions are true or false: a true, proposition unites ideas that agree, and separates those that disagree, as “God is good.” “Men are not truly wise.” A false proposition affirms an agreement between ideas that disagree, and a disagreement between those which agree, as “A good king oppresses his subjects.” “Virtue is not the road to solid happiness.” . A demonstrable proposition is one that may be proved by a train of reasoning, called demonstration, as “Any two angles of a triangle, taken together, are greater than the third.” Illustration: Demonstration is a succession of connected pro- positions, beginning with self-evident, and advancing to remoter truths: such is the mathematical demonstration, which begins with definitions: from these it advances to axioms, or self- evident propositions; and thence to more remote truths. Corollaries are inferences deduced from truths already demonstrated. Of Reasoning. Reasoning determines the relation between º e two or more Fig. l. Fig. 2. ideas, by the B JB intervention of another, or third idea. Illustra- r, tion : If I wish to compare two right lined fi- gures, as A B C DE, and A B C The senses teach us the existence, + given figures. All right-lined figures may be divided into triangles, and the areas of all triangles are equal to the base multiplied into half the perpendicular height. Hence Illustration: The province | DEF, (see fig, 1 || * and 2.) with regard to magnitude, I find the thing impossible, on account of their disagreeing forms, one having six sides, and the other only five. I must therefore look for a third idea, in this case, a third figure, with which I may compare both the I easily compare the two given figures, in respect to magnitude, by the intervention of the third idea, a triangle. See the articles GeoMet RY and MENSURAtion. - If the two given ideas agree with the third idea, it is evident that they must agree with each other. If one agrees, and the other disagrees, their mutual disagreement is inferred. - Every act of reasoning consists of three judgments, in two of which the given ideas are compared with the third idea, and in the last they are joined to or separated from each other. Illustration: In the figures above mentioned, the first two judg- ments are employed in considering into how many triangles each figure may be divided ; and in the last judgment, we compare them together with respect to magnitude. * A syllogism is the expression of an act of reasoning, and includes three distinct propositions. The intermediate idea made use of, (as that of a triangle just noticed,) to discover the agreement or disagreement we are in search of, is called the middle term, and the two ideas with which this third is com- pared, are called extremes. - - Example 1. Suppose a comparison to be made between industry and honour, and utility be the third idea, then the syllogism will stand, - • - Whatever is useful is honourable. - * * Industry is useful; Therefore industry is honourable. Example 2. If the inquiry be, whether a man is bound to cultivate his mind, I say, - - Every creature possessed of reason is bound to cultivate - his mind. Man is possessed of reason; Therefore man is bound to cultivate his mind. In syllogisms the proposition containing the inference is called the conclusion ; the two preceding positions are the premises. Of the two premises, that is called the major proposi- tion in which the greater extreme is compared with the middle term; the minor proposition is that in which the less extreme is compared with it. Example. In the syllogism, Truth is venerable. Christianity is truth; - Therefore Christianity is venerable. * “Christianity,” “Venerable,” and “Truth,” are the three terms of the syllogism. “Christianity” and “Venerable” are the extremes, and “Truth” is the middle term. “ Venerable” is the major, and “Christianity” the minor term. “Truth is venerable,” “Christianity is truth,” are the premises ; “there- fore Christianity is venerable,” is the conclusion. “Truth is venerable,” is the major proposition ; “Christianity is truth,” is the minor proposition.* - - [Syllogisms may be almost indefinitely varied, and each variety has obtained a distinct name: in this place a very few will be noticed.] Hypothetical syllogisms are those in which the major premise is an hypothetical proposition. - Exam. If there be a God, he ought to be worshipped. But there is a God; - \ Therefore he ought to be worshipped. . A dilemma is a syllogism in which the consequent of the major is a disjunctive proposition, which is taken away in the minor: or it is an argument by which we endeavour to prove the absurdity or falsehood of some assertion. - Exam. If God did not create the world perfect in its kind, it must have been from want of inclination or power. But it could not have been from want of inclination, or want of power. - - . . Therefore he created the world perfect in its kind. * See “A Compendium of Logic, by the Rev. Thomas Belsham, as introl ductory to his Elements of the Philosophy of the Human Mind,” &c., , ; L O N L O O. DICTIONARY OF MECHANICAL SCIENCE. 593 Analogy is an argument from proportionable causes to propor- tionable effects; and from similarity of circumstances to simi- larity of consequences. Ex. All matter with which we are acquainted gravitates; Therefore gravitation is an universal property of matter. Illustration: By this mode of argument, we infer that the sun will rise to-morrow, and the next day, and so on. Thus the philosopher believes that the planets are inhabited: and the man of business regards it as certain that a dishonest and ava- ricious man will take an undue advantage in trade, where the opportunity occurs, as that fire will burn, or a ball will roll down a hill. In other cases the argument cannot be much de- pended on, as when we intend to draw conclusions concerning the conduct of voluntary agents; this is owing to the difficulty which one person has to enter into the views, objects, and feel- ings of another, and consequently to foresee in given circum- stances, how another man will act. LOGWOOD. The tree which yields it is called by Linnaeus, haematoxylum campechianum. Logwood is so heavy as to sink in water, hard, compact, of a fine grain, capable of being po- lished, and scarcely susceptible of decay. Its predominant colour is red, tinged with orange, yellow, and black. It yields its colour both to spirituous and watery menstrua. LOLIUM PerenNe, Ray or Rye-grass. This has been long in cultivation, and is usually sown with clover under a crop of spring corn. It forms in the succeeding autumn a good stock of herbage, and the summer following it is commonly mown for hay, or the seed saved for market, after which the land is usually ploughed and fallowed, to clear it of weeds, or as a preparation for wheat, by sowing a crop of winter tares or tur- hips. The seed is about six or eight pecks per acre, and ten pounds of clover mixed, as the land best suits. Although this is a very advantageous culture for such purposes, and when the land is not to remain in constant pasture; yet it is by no means a fit grass for permanent meadow, as it exhausts the soil, and presently goes into a state of decay for want of nourishment, when other plants natural to the soil are apt to overpower it. There are several varieties of this grass: some with the flowers double, others with branched panicles; some that grow very luxuriantly, and others that are little better than annuals; and there is also a variety in cultivation called Pacey's rye-grass, much sought for. But a fine rich soil only will produce a good crop, and the principal difference, after all, is owing more to cultivation or change of soil, than to any real difference in the plant itself. LONG, Roger, an English astronomical professor, was born in 1679, and received his college education at Cambridge; he became master of Pembroke Hall, and Lowndes's professor of astronomy. He is chieſly known as an author, by a treatise on astronomy, in two volumes; the first of which was published in 1742, and the second in 1764. LONGIMETRY, the measuring of lengths or distances, both accessible and inaccessible. Accessible distances are mea- sured by the application of some measure a certain number of times, as a foot, chain, &c. And inaccessible distances are measured by taking angles, &c. by means of proper instru- ments, as the circumferentor, quadrant, theodolite, &c. This embraces a great number of cases, according to the situation of the object and observer, a variety of which are given in vari- ous parts of this Dictionary. r LONGITUDE, in Astronomy, is the angular distance of any star or celestial body from the vernal equinoctial point, that is, if a great circle pass through a star perpendicular to the eclip- tic, the arc of the ecliptic intercepted between the intersection of it with this circle, and the vernal equinoctial point, will be the longitude of the star. LONG ITUDE, in Geography and Navigation, is the measure of the angle included between the meridian of any place, the longitude of which is required, and a certain fixed meridian from which the longitude is reckoned; or it is the number of degrees, minutes, &c. intercepted between a certain fixed point of the equator, and the intersection of the meridian of the place with the same circle. This we have illustrated; see LATITUD e. Degrees of Long ITU De vary with the parallels of latitude, being every where as the cosine of the latitude. The following Table shews the length of a degree of longitude, correspond- ing to every degree of latitude from the equator to the pole, as expressed in English and geographical miles. TABLE. * |ºn. 㺠Teg. |Deg. Lon. Rººi P; ſº. #. ‘ī; ſºilº ºf #; ºffº § 1. #: *ś 0 | 60:00 gº 30 || 51.96 || 59.93 : 60 || 30-00 || 24.60 I 59.99 || 69-19 : 31 || 51.43 || 5932 : 61 29.90 33.55 2 || 5996 || 69-16; 32 50.88 5869 ; 62 28-17 | 32.49 3 59.92 || 69°11 § 33 || 50.32 58.04 $ 63 27-24 31:42 4 59.85 69-03 ; 34 49.74 57.37 § 64 26-30 || 30-34 5 59.77|| 6894 : 35 | 4915 56-69 ; 65 25-36 29:25 6 || 59.67 | 68-82 & 36 48.54 55.98 : 66 24.40 28:15 7 59.53 | 6869 ; 37 4792 || 53.27 67 || 23.45| 27:04 8 5942 | 6853 : 38 47-28 || 5453 : 68 22.48 25.92 9 || 59:26 | 68.35 § 39 46.63 53.78 : 69 21:51 24.80 10 || 5909 | 68: 15 $ 40 || 45.96 53:10 # 70 | 20:52 || 23.67 11 : 58.89 || 67.93 : 41 || 45-28 || 52.23 : 71 | 1953 22:53 12 58.69 67-69 ; 42 44'59 || 51.43 ; 72 1854 21:38 13 || 5846 | 67.43 : 43 43.88 50.6, $ 73 || 17:54 2023 14 5822 67.14 ; 44 43:16 4979 $ 74 16:54 19:07 15 57.95 | 6684 45 42:43 || 4893 : 75 15:53 1791. 16 || 57.67 | 66.52 46 || 41.68|| 4807; 78 14:52, 1674 17 | 57.38 | 66.18 : 47 | 40.92 || 47.19 ; 77 | 13:50 15.57 18 57.06 || 65.81 : 48 || 40:15 46:30 ; 78 || 12:48 14:39 19 56-73 || 65.43 & 49 || 39'36 45.40 : 79 || 11:45 13-20 20 56.38 65.27 § 50 38.57 44.48 ; 80 | 10:42 | 12:02 |. 21 56-01 || 64.60 : 51 || 37.76 43’55 ; 81 9:38 || 10-83 22 || 55 63 6406; 52 36.94 || 42.60 $ 82 8:35 9:63 23 55.23 63-70 $ 53 : 3611 || 41.65 : 83 || 7-31 | 843 24 54.81 63.22 $ 54 || 35-27 | 40.68 ; 84 || 6-27 | 723 25 54:38 62.72 ; 55 34.41 39.69 ; 85 5-22 || 6-03 26 53.93 62.20 $ 56 || 33'55 38:70 $ 86 || 4:18 || 4-83 27 53.46 || 61-66 & 57 || 32.68 || 37.69 ; 87 || 3:14 || 3:62 28 52.97 61:10 # 68 31.79 36.67 88 || 2:09 || 2:42 29 52:48 60:52 : 59 30.90 35.64 : 89 || 1:05 || 1:24 LoNGITUDe Stars, is a term used to denote those fixed stars which have been selected for the purpose of finding the longi- tude by lunar observations; as, a Arietes, a small star without the zodiac, about 22° to the right of the Pleiades. Aldebaram, in the Bull's-eye, a large star, about half way between the Pleiades and the star which forms the western shoulder of Orion. a Pegasi, a star about 44° to the right of a Arietes, nearly in a line with this latter star and the Pleiades. Pollua', to the northward of Aldebaran, one of the two bright stars in the constellation Gemini. Regulus, about 38° S E of Pollux, the southernmost of four bright stars to the N. E. of Aldebaram. Spica Virginis, a white sparkling star, about 54° S. E. of Regu- lus. Antares, lying to the right hand of Regulus, and about 450 from Spica Virginis. Formahault, lying about 45° to the south of a Pegasi. a Aquila, a star about 47° to the westward of a Pegasi. Longitude by Time Keeper, is estimated by the difference between the time at the place, and the time indicated by one of those improved watches, called time keepers. LOOF, the after part of a ship's bow, or that where the planks begin to be incurvated as they approach the stem. Hence the guns which lie here are called Loof Pieces. LOOK-OUT, a watchful attention to some important object or event, which is expected to arise from the present situation of a ship; there is always a look-out kept on a ship's forecastle at sea, to watch for any dangerous object lying near her track, or for any strange sail heaving in sight, &c. The officer of the watch accordingly calls frequently from the quarter deck, to the per- son appointed for this service, “ look out afore there.” - LOOMING, an indistinct appearance of any distant object, as the sea-coast, ships, mountains: “that ship looms large,” “ the land looms high, &c. - 7 M 594 L J O L O O DICTIONARY OF MECHANICAL SCIENCE. LOOMS, Power. The number of powerlooms in the manu- facturing district which surrounds Manchester has been, after, careful inquiry, stated to be 30,000. sº The quantity of cotton converted into yarn in * , Great Britain and Ireland in one year is # * * ...about..... .*.*.*.*… • e e s s a • *-* : • * * * * * * * * * * • ** 50,000,000 lbs. The loss in spinningºsy be estimated at 1% ºf on per lb., sº .... . . . . . . . . . . . . . . . . . ºOOO,000 lbs. Quantity of yáñº àuced. . . . . . . . *T**: * * *. 1ºooooooibs. * • *, * ~ *, * * * ** - - : ºf * - . . - Amount, supposing 1s. 8d. to be the average, ... price per. lb. • * e e g º e º e º & © e e e º O & C o º O e º & £ 10,875,000. If every person employed in spinning produces 900 lb. per annum, the number of persons employed is 161,111. The num- ber of spindles employed, supposing each to produce 15 lb. weight per annum, is 9,666,666. The capital invested in build- ings and machinery cannot be less than £10,000,000. It is cal- culated that the rental of Manchester, including Salford, Chorl- ton, Rew, &c. which form part of the same town, will be increased at least £15,000 this year (1825) by new buildings. The increase is chiefly in cottage property, under £12 a year rent, - - Goodman’s Improved Silk Loom.—The improvements of this machine apply to that description of loom that usually weave narrow articles, as tapes and ribbons, (commonly called Dutch engine looms,) and consist principally in a novel arrangement of the shuttles and slays in the battens. The general appear- ance of the loom, with its improvements, is shewn in the plate, fig. 1, which is an end view of the machine, exhibiting the dis- position of the warps for two sets of shuttles. Fig. 2, shews a part of the front of the batten; and fig. 3, the back of the same; by which the situation of the shuttles, and manner of fixing the slays will be seen, and also the construction of the driver. The front of the batten, fig. 2, is formed by three planks, one of which is fixed to the top-rail by a series of slay screws: the bottom plank is secured to the lower rail in a similar manner; and the middle plank is fastened to the slay rail by a series of screws or pins, as seen in the back view, fig. 3. These screws must have shoulders to leave an open space between the back of the plank and the slay rail, for the action of the drivers. The shuttles made in the ordinary construction, are introdu- ced in the races between the planks, and the horizontal action of the drivers impels them to and fro through the warp, in the usual manner. The driver in the ordinary engine loom is formed like a ladder, but in this improved loom it is made with teeth extending from the top and bottom rails of its frame, shewn by dots; and these teeth may, if it should be thought desirable, be united together for the purpose of giving them stability, by dia- gonal pieces crossing the middle of the batten. - For the general operation of the loom, see the Plate of Looms: bb, fig. 1, are the rollers, upon which the material is wound, to form two warps; from thence the threads proceed (as shewn by arrows in the figure) in the usual way, up and down over the weighted pulleys, to the back slays b, then under the warp-rol- lers c to the leashes d, which are looped to arrange with each set of warps, and through which each distinct warp passes to its respective slay. The raising and depressing of the treadles e, worked by the feet of the weaver, cause the leashes alternate- ly to move up or down, by which the warp threads are opened; the batten f is then pushed back, and the shuttles passed through the open space between the threads. The shifting of the treadles and leashes now cause the intervention of the threads to be made fast, which are beaten up firm, by bringing the batten f forward. The continued action of the loom in this manner, and the passing of the shuttles to and fro, produces ration of weaving. - The work thus woven, is drawn off through small apertures in the breast piece g, and thence proceeds to the work roller h, over which it passes up the back castle i, where it is distended by the weighted bags and pulleys; from thence it is carried over the top castle k, and through holes in the work castle, l, where it is made fast by wedges, to prevent it from running back, and as the length of the work accumulates, it is wound round the bobbins m. *Although we have described the whole construction and ope- ration of this improved engine loom, the inveniion claimed by º patentee consists merely “in the new arrangement of the shuttles and the slays, as connected with the batten and the knitting of the leashes, to arrange with the same in the manner above described. * r -- Description of an improved Loom, by which Purses, Pockets, Sacks, &c. may be woven without requiring a Side-seam, and Work in general may be better eacecuted.—In this loom, represented by fig. 10, (see Plate of Looms,) an oblong frame, A, is laid down horizontally, and secured at the four corners with triangular braces, to keep the frame properly square. Three of these braces, B B B, are visible. Four posts, C C C C, are fixed up- right in mortise holes on the above frame. The front posts are supported, both behind and before, with diagonal timbers, D D D D, to keep the breast-roll E from giving way in the least by the heavy stroke of the batten. FF, on the quarter or work. The two hinder posts, G-G, are held firm by two dia- gonal supports, HH, within the loom, to bear against the counter-weights II, and the great weight V, hanging on the work K, and the force of the batten F. A loom constructed upon this plan, without shorings or sup- ports, will make both strong and slight works firm and good, and its advantages are therefore more important than might be supposed. As journeymen weavers generally live in low- rented houses, the floors and party-walls of the rooms where they weave, are mostly bad and weak; so that the common looms cannot be firmly placed, and the man finds great diffi- culty in getting his loom into tolerable order; yet if the loom is not set square, and prevented from giving way, while used, no work can be made strong and good. The silk chafes and cuts, and the workman is harassed for want of knowing the real cause of the mischief, or not having skill to correct it. These inconveniences are obviated by the bottom frame braced as above mentioned; any ordinary workman can set up this loom well, though it requires a person of considerable judg- ment to set up an ordinary one. It is a common fault, where shorings or supports are used, to make them too long and slender, in which case, even when they, rest against good walls, there is a trembling motion, and if the shake only amount to the hundredth part of an inch, it will take out that stiffness which ought to be in the work. In consequence of the defects thus occasioned in the manufacture, the poor weaver is often turned out of employment, and the master suffers in his property, as he cannot sell the fabric at the price it ought to be worth. A variety of other disadvantages, well known to the trade, attend the use of the loom, not properly squared, shored, and fixed; but it may suffice to refer to one, which is material. A loom set up with stays, must remain always at the same place, although the light may frequently not be suitable to the work, and even when the moving of the machine a few inches would render the light proper. In this point of view, the improved loom is particularly convenient. Method of Weaving Sacks, &c. in the Loom above described.—L, the seat of the loom. M, the treadles, six in number, to raise the harness. N, the counter-meshes to raise the tumblers O, moveable on a pin a little beyond their centre, and which act on the harness P, by raising such parts thereof as they are attached to at their extremities. Q, the work in the loom. R, the reed which strikes the shoot or weft close up. S, the back beam on which the warp or thread is wound. TT, the rods to preserve the crossings of the threads. V, the main weight sus- Apended by a lever U, from a bar W near its centre; the other end of the lever is fastened by a cord to the bottom frame of the loom at X. Y, the rack on the working beam. Z, the º e catch, to hold the teeth of the rack. that intervention of the waft and weft which is the ordinary ope- | To weave a sack, press down the second treadle on the right hand side, and throw one shoot with the shuttle; next press down the second treadle on the left hand side, and throw another shoot; then proceed in the same manner with the third on the right, and the third on the left, till a sufficient quantity is made; then work the two outside treadles and two shoots. In weaving sacks, it is necessary, between the finishing of one sack and the commencement of another, to pass a thin slip of wood through the threads, in order to form a space between the two sacks. - ^ //, - - –––. ||| T 1. - - /* * * oſmºs ºl- - uſ!" * "Timm | || | | - Zoo” ºr Mºnº º |, º - |o - - /*ockeys tº yoºs, º /*- M. º.º. - /**, * * wºrhoºf a wºe-sear”." ºubº º Fºº L O O L do 595 DICTIONARY OF MECHANICAL SCIENCE. A. Edom fºr Weaving Fishing-nets.--A machine for weaving fishing-nets has long been , a desideratum; fishermen fre- quently having their nets broken by dog-fish, and other marine animals, and they experience many difficulties after such acci- dents, on account of the length of time required by the present mode of netting, in repairing their injured nets, or in making others. A fisherman is sometimes compelled, from these ob- structions, to relinquish fishing for a whole season. . Any method, therefore, which leads to accelerate the fabrication of nets, without increasing the expense of them, must be beneficial to the community. These considerations swayed the inventor of the loom described below, in devoting much of his attention to this branch of manufacture, until he succeeded in uniting economy and expedition. The loom is represented by figs. 1 to 9, in the Plate. Fig. 1, is the machine in a state ready to begin working, supported in a wooden frame. A is a beam on which the twines for the net are rolled, in number equal to the knots tied, and from which they pass through circular tubes fixed in a bar B, (shewn by dotted lines through the pulley, but seen better in fig. 2,) which is fixed near the circumference of two equal pulleys, C C, that turn on their axes by means of a cross treadle, with small pulleys at each end, D D, through which passes a band, one end of which is fastened on the frame at E, and the other on the pulley C. At F, the band through the other pulley has one end fastened on the frame at G, and being wound round the farthest pulley C, is fastened on the under side of it, which, by the alternate action of the treadle on its axis H, moves the pulleys C C, and circular tubes, from their situation in fig. 1 to that in fig. 3, and back again. In the centre of the pulleys C C, is fixed another bar P with a dove-tail groove, where the pirns that contain the twine are supported, (it being necessary to have two threads for every mesh, also one pirn more than there are tubes.) In a groove under the dove-tail is a slider L, moved by a wire K, fixed in each end of it, having pins in it, by which it moves the pirns backwards or forwards over the notches in the bar I, so as to cast a part of the knot: the pulleys C C, and bar B, move round the bar I as an axis, but independent of it; the bar I being fastened through the pulleys to the frame. M is a moveable bar (centred within two supporters, N N, having two joints) with hooks, both for catching the twine at the end of the circular tubes, and by crossing the hooks to the other side of the points of the tubes, to give the twine a turn for forming the knot; and by raising the points of the hooks, the ends of the tubes enter between them, as shewn in fig. 4, and by the circular motion of the bar B, when the two pulleys C C are turning on its centre by the foot, on the end, No. 1, of the cross treadle; and until the knots so formed are close to the bar B, fig. 3, (it is then what is called a running knot,) a part of which falls into a notch cut below the level of the sup- porters of the pirns in the bar I; the pirns must then be slidden over the notches that contain the twine, the knot is then cast, and then by the foot on the other end, No. 2, of the cross treadle, the points of the tubes are returned to their former position; remove the knot by disengaging the hooks and the tubes, the knots are then made tight as the wrought part of the net is rolled on the beam O, on one end of which there is a pulley, P, with a band that communicates with the pulley on the end of a short roller Q, in which are fixed four cross bits of wood, that answer the purpose of treadles for the feet, by which it is drawn tight. R is another short roller, communicating with the roller A, serving to give out the proper quantity of twine for the length of the meshes, or to hold it while the other roller tightens the knot. S is the seat. Fig. 2, is a plan of the machine; the moveable bar and treadles are left out to prevent confusion. Fig. 3, is the situation of the running knot when the pirn goes through it. - Fig. 5, is the tube in the same position, shewing the manner in which the knot is twisted round it; and having the pirn and slider L taken out of the bar I, the dotted lines shewing at what height they come together. In the slider L there are two pins, TT, to prevent its rising high enough to touch the string; and in the bar I there ale two wires OO, like staples, to sup- port the slider L in its place. * - Fig. 6, is the moveable bar M with the hooks. Fig. 7, shews the hooks at large. - Fig. 8, is the bar I, shewing the notches in which the strings lie to let the pirns pass over them, (when the tubes are brought over as in fig. 3.) - - Fig. 9, is the slider L, with the pins that move the pirns. , It appears, by a statement of the inventor, that the nets used in the northern fisheries are of one breadth throughout. He estimates that he can make three courses of one hundred meshes each, in one minute; that such a loom should be about 33 feet wide, and would cost about fifteen or sixteen pounds. A Loom to be worked by Steam or Water.—A loom having been invented, which may be wrought by steam, water, or any other first mover of machinery, and its practical value having been ascertained by an extensive trial, it will be interesting and useful in this publication, to shew what has been accom- plished in this branch of ingenuity, by a record of its proper- ties. A plate of any ordinary size would not be adapted to shew with clearness the principles and construction of this curious machine; but a working model is in the possession of the Society for the Encouragement of Arts, &c. and looms upon this plan possess the following advantages:—1. From 300 to 400 of them may be worked by one water-wheel, or steam- engine, all of which will weave cloth, superior to what is done in the common way. 2. They will go at the rate of 60 shoots in a minute, or two yards of a nine-hundred web in an hour. 3. They will keep regular time in working, stop, and begin again, as quickly as a stop watch. 4. They will keep con- stantly going, except at the time of shifting two shuttles, when the weft on the pirns is done. 5. In general, no knots need to be tied, and never more than one, in place of two, which are requisite in the common way, where a thread breaks. 6. In case the shuttle stops in the shed, the lay will not come for- ward, and the loom will instantly stop working. 7. They will weave proportionally slower, or quicker, according to the breadth and quality of the web, which may be the broadest now made. 8. They may be mounted with a harness, or spot headles, to weave any pattern, twilled, striped, &c. 9. There is but one close shed, the same in both breadths, and the strain of the working has no effect on the yarn behind the rods. 10. The bore and temples always keep the same proper distance. ll. There is no time, lost in looming, or cutting out the cloth; but it is done while the loom is working, after the first time. 12. The weft is well stretched, and exactly even to the fabric required. 13. Every piece of cloth is measured to a straw's breadth, and marked where to be cut, at any given length. 14. The loom will work backwards, in case of any accident, or of one or more shoots missing. 15. Every thread is as regular on the yarn beam as in the cloth, having no more than two threads in the runner. 16. If a thread should appear too coarse or fine in the web, it can be changed, or any stripe altered at pleasure. 17. They will weave the finest yarn more tenderly, and regu- larly, than any weaver can do with his hands and feet. 18. When a thread either of warp or weft breaks in it, the loom will instantly stop, without stopping any other loom, and will give warning by the ringing of a bell. 19. A loom of this kind occupies only the same space as a common loom; the expenses of it will be about half more; but this additional expense is more than compensated by the various additional machinery employed for preparing the yarn for the common loom, and which this loom renders entirely unnecessary. 20. The reel- ing, winding, warping, beaming, looming, combing, dressing, fanning, greasing, drawing bores, shifting headles, rods, and temples, which is nearly one-half of the weaver's work, toge- ther with the general waste accompanying them, which is about six per cent. of the value of the yarn; and all which occur in the operations of the common loom, do not happen with this loom, which, by its single motion, without further trouble, per- forms every operation after the spinning, till the making of the cloth be accomplished; by which, independently of the saving of the waste, the expense incurred for reeling, warping, wind- ing, &c. is saved, amounting to above twenty per cent. of the yarn. , than usual, from the regularity of their motion. 22. More than 21. The headles, reed, and brushes, will wear longer 596 L O O L. O. O. DICTIONARY OF MECHANICAL SCIENCE. one-half of the workmanship will be saved; one weaver and a boy being quite sufficient to manage five looms of coarse work, and three or four in fine work.-The first attempt of the inven- tor of the above loom, towards constructing such a machine, was made in the year 1789; at which time he entered a caveat for a patent, but relinquished the idea of obtaining one, and afterwards made many improvements upon the original plan. In 1796, a report in its favour was made by the Chamber of Commerce and Manufactures at Glasgow; and in 1798, a loom was actually set at work, in J. Monteith's spinning works, at Pollockshaws, four miles from Glasgow, which answered so well that a building was erected by J. Monteith to hold thirty of the looms, and afterwards another to hold two hundred. Among the most ingenious inventions, or rather improve- ments in this useful machine, is the Patent Power Loom, invented by Archibald Buchanan, Esq. of Catrine Cotton-works, one of the partners of the house of James Findlay and Company, whereby a greater quantity of cloth may be woven in a given time without injury to the fabric, than by any application of power for that purpose heretofore employed. This invention consists in the application of two eccentric wheels, A and B, represented in fig. 12, (see the Plate,) to a weaving-loom, impelled by machinery, as repre- sented in figs. 11 and 12; and the application of these wheels to the said loom is particularly exhibited by fig. 12, as explained by the description hereinafter set forth. The inventor claims no part of the said loom, or of its construction, as his invention, or as forming any part of his right of patent, except the appli- cation thereto of the said two eccentric wheels. A reference to the drawings in fig. 11 and 12, and the de- scription hereunto annexed, will enable any person of ordinary mechanical skill, to understand and execute the application and operation of the said two eccentric wheels, either to this loom, or, by slight alterations which will be obviously suggested, to the ordinary weaving looms at present, in use by the public. upon its centres below, is connected with the eccentric wheel, B, by means of the crank-rods, at F. This wheel or pinion, B, receives its motions from the wheel A, and the method by which these wheels are constructed, and the manner in which they are applied, are now to be particularly described. Both wheels, as already mentioned, and as will at once ap- pear by inspecting the drawings, and, more particularly, fig. 12, are what is usually termed eccentric—that is to say, their circumferences, in which the teeth are cut, deviate from the common circular form, in such a ratio as may be required, in order to give the desired motion to the lay. In order to con- struct such a wheel A, in weaving plain cloth, and which is fixed upon the treadleshaft, q, in fig. 11 and 12, the following descriptions and explanations, if carefully attended to, will be sufficient. Its greatest diameter being about 19 inches, and its smallest diameter about 16 inches—its deviation from the circular form amounts to about three inches. This “deviation, however, may be increased or diminished, at the discretion of the constructor, and according to the variation of velocity which he wishes to communicate to the reciprocating motion of the lay. To obtain the proper curve of eccentricity, let two eccen- tric circles be drawn, corresponding with the greatest and small- est diameters. Divide these circles into any convenient num- ber of equal parts; as, for example, 64, and draw radii from the centre to the points of division in the external circle. Di- vide the space between the circles into the same number of equal parts with the circumference, one of which being set off upon the first radius, two upon the second, and so on progres- sively, until the whole are set off, points will be obtained, through which a curved line being drawn, the required form of the cir- cumference will be marked off upon each quadrant of the wheel. The highest points, as will appear by the drawings, are at the two extremities of a diameter line, bisecting the external circle. and the lowest points, at the extremities of another diameter line, bisecting the internal circles at right angles to the former. Thus, the form obtained bears some resemblance to an ellipse, with its conjugate and transverse diameters. The pinion B must of course be constructed so as to correspond with, and work into, the wheel A. To effect this, it is merely necessary to draw circles as in the former case, corresponding with the greatest and the The lay g, attached to the rod h, vibrating smallest diameters required. Then set off one-half of the radii drawn upon the wheel A, the pinion being half its diameter, and add, progressively, to each radius of the pinion, as many equal parts as were taken from each corresponding radius of the wheel, and vice-versa. The semidiameter of the pinion will thus correspond, in every point with each quadrant of the wheel, and the pinion will revolve twice whilst the wheel per- forms one revolution, as before stated—thus communicating two accelerated strokes to the lay, for each revolution of the trea- dle-shaft moving the wheel A. The circumferential forms of both being thus obtained, the teeth are to be cut and rounded off so as to work properly into each other in revolving upon their respective axes. Though the wheel A will thus produce two revolutions of the pinion B, other proportions may be adopted when deemed expedient, and as may suit the motions to be communicated to a greater number of treddles for weaving plain, tweeled, or figured cloths. Those conversant with the art of weaving, will at one perceive, that a varied speed applied to the reciprocating motion of the lay, is of the greatest advan- tage, and such as will keep the lay as nearly stationary as con- venient at the point where the shuttle is thrown across the web; and when the shed, or divided portions of warp, are sufficiently open to allow the shuttle to pass without injury to the warp threads. The lay, in returning, drives up the woof to the fell or verge of the cloth, with a smart stroke, whilst the shed or di- vided portions of warp are closing upon it, and when the least tension is given by the treadles to the warp threads. Mr. Bu- chanan ascertained, by experience, that in looms having such wheels, and the other apparatus before described, attached to them, the shuttle may be thrown across a web, 36 inches wide, 130 times per minute, without creating more breakage, in pro- portion to the quantity woven, than occurs in looms driven at the rate of 80 to 90 crossings of the shuttle per minute.* r Description of the Drawings.-The construction of the wheels A B, upon the application of which the patent is claimed, is delineated on the drawing, ſig. 12. Figs. 11 and 12 exhibit the two end views of the loom. In the following description, the same letters of the alphabet, and nu- merals, denote the same things in all the figures. CD EF, denote the frame.-a, the strap communicating mo- tion to the loom, at b ; b, the fast and loose pulleys; c, a pinion fixed on the end of the pulley-spindle, and working into the wheel d, of triple the diameter, gives motion to the wiper-shaft, q. (See fig. 11.)—k, the lever and fork; and l, the spring for engaging and disengaging the loom at pleasure. (See fig. 11.) A lever is connected with the protecting pin of the lay, 2, for disengaging the loom, should the shuttle remain in the shed ; m, a small eccentric wheel, fixed on the end of the wiper-shaft, q, (see fig, 11,) and connected with the lever n, (see fig, 11,) on the top of which is jointed a circular piece of iron, o, (see fig. 11,) which acts on the ratchet wheel r, and draws up the cloth as it is woven ; and for varying the fabric in thickness, a ratchet- wheel of more or fewer teeth is applied; p is a catch bent in the same manner as o, which prevents the ratchet wheel, r, from returning back. By raising the handle pºp, these catches are all disengaged. Behind the ratchet-wheel r, is fixed a small pinion working into the wheel, which is fixed on the end of the cloth- beam, t, (see fig. 11,) and covered with a card fillet for holding the cloth; ac, is a small roll which receives the cloth from the beam t, and round which it is wound, by the motion of the beam t , e, the crank shaft which receives motion from the wiper-shaft, q, by the wheels A and B; f, the connecting-bar; g, the lay; h, the lay- sword. (See fig. 11 and 12.) S, the headle-roll bearer. (See ſig. 11 and 12.) Q, the yarn roller bearer. (See fig. 11 and 12–11, the yarn-roll. (See fig. 11 and 12.) 14, a screw-box. (See fig. 11.); 1, is the protecting catch, for disengaging the loom when the shuttle stops in the shed; this catch is connected with a rod passing along the lay, on which the shuttle springs in the boxes act; when the shuttle fails to enter the box, this catch falls down, and, striking against the pin, 2, the lay is held fast, and the loom instantly disengaged by its connexion with the * We understand that the patentee of this most important invention has himself driven the shuttle across the web 160 times per minute, without injury to the cloth; a speed which is nearly double of that of the looms at present in use. - • * * L O O L O W DICTIONARY OF MECHANICAL SCIENCE. 597 lever which acts on the handle of the loom b. (See fig, 11 and 12.) 33, the heddle wipers, which, by acting on the friction pulleys fixed to the treadles, b b, alternately elevate and de- press the treadles. (See fig. 12.) . 77, the short marches con- necting the heddles, 8888, with the treadles, 66. (See fig, 12.) 44, friction pulleys, fixed to the heddle-wipers, 33, acting al- ternately on the treadles 55, to which the picking peg, q, for throwing the shuttle, is connected by bolts and screws ; 10, is the warp-yarn beam. (See fig, 12.); A B, the eccentric wheels, for giving motion to the lay g. (See fig, 12.) y, the bearer of the boltfork, k, and which extends so as to connect another loom. (See fig, 11 ;) 14, the friction wheel; its appendages are two plates fastened to the beam-shaft, and upon one of them is glued a piece of leather, which is made perfectly flat by turning; the face of one of the appendage wheels is also turned flat, but this wheel is loose on the spindle; on the outside of it is the screw- box, 14, the outer part of which is made fast to the beam shaft, by a pin passed through it, the inner part of the box is then screwed up against the outer face of the said wheel, which presses the two surfaces together, and any degree of tension can be given to the warp-yarn by more or less screwing of the box, 14. (See fig. 11.) There is a small pinching screw-pin which is screwed into the outer box, the point of which enters a small cavity in the inner part of the box, and prevents it from un- screwing. 17, the long heddle marches connected to the hed- dles, 8, by cords, and to the short marches, 77, by wires. (See fig. 12.) j, the bearer of the pulley-shaft. (See fig. 11.) Method of Weaving Cloth of extremely Fine Quality.—This improved mode of weaving consists in adding more thread of the warp within each dent or split of the reed than in the com- mon way; for instance, where in the common mode there are only two threads in the reed, there are upon this plan three or four. The weft or shoot is thrown in the common way with a single thread. When the cloth is woven and taken out of the loom, it has the appearance of being barred or striped, the cane of the reed occasioning that part of the cloth struck with it to look thinner, owing to the threads of the warp being fur- ther apart. The cloth is then to be wet in water, and in that state to be repeatedly stretched across by the hands backwards and forwards corner-ways ; by this means, the threads which apparently formed the stripe, or close part of the cloth, sepa- rate from each other, and become diffused at equal distances. The appearance of stripes being entirely removed, the cloth becomes of inconceivable fineness, and extremely regular in texture. This operation must, in cotton fabrics, be performed before the cloth goes to the bleach-ground. Silk goods, on being taken out of the loom, must be wet and well rubbed, as in the common mode of washing, and then stretched back- wards and forwards, in the manner above directed for cotton goods. In silk goods the warp and weft may be both alike ; in cotton goods the weft may be softer, but of the same fineness. Fine linen cambrics may be made on this plan, much superior to any hitherto made in France. Though there are three threads within each dent or split of the reed, whilst the cloth is weaving, yet the headles or yealds lift up their threads alter- nately throughout the whole breadth of the cloth, and there are about 250 shoots in an inch. By this improvement, cotton, linen, and silk goods, can be made much sooner and finer, than by any method yet discovered. The inventor of it made a piece of plain silk cloth, from hand-thrown silk in the gum, that con- tained the amazing quantity of 65,536 meshes in one square inch. It is impossible to make a reed half so fine as to weave such cloth upon the present principles of weaving ; and even if that could be done, no weaver could make use of it: but upon the above plan, which the inventor asserts he can teach in two minutes, as fine cloth may be woven in a twelve hundred reed, as by the old mode in a reed of twenty-four hundred, and with less rather than more trouble. LOOP Holes, certain small apertures formed in the bulk- heads and other parts of a merchant ship, through which the small arms are ſired on an enemy who boards her. . LOOPING, in Metallurgy, a word used by the miners of some counties of England, to express the running together of the matter of an ore into a mass, in the roasting or first burn- ing, intended only to calcine it so far as to make it fit for pow- deriº; This accident, which gives the miners some trouble, is generally owing to the continuing of the fire too long in this process. - - • LOPEZ, or INDIAN-Roof, in the Materia Medica.—The plant to which this article belongs is unknown. Neither the woody nor cortical part of the root has any remarkably sensible quality. A slight bitterness is perceptible; and it is recom- mended, like simarouba, in diarrhoeas, even of the colliquative kind, in half-drachm doses four times a day. Little of this root has been brought to Europe; but some of those who have had an opportunity of employing it, speak in very high terms of the effects obtained from it. • LOPHIUS, Fishing Frog, Toad-fish, or Sea-devil, a genus of the branchiostegöus order of fishes. LORANTHUS, a genus of plants belonging to the hexandria class, and in the natural method ranking under the 48th order, Aggregatae. LORD, a title of honour given to those who are noble either by birth or creation. In this sense, it amounts to much the same as peer of the realm, or lord of parliament. The title is by courtesy also given to all the sons of dukes and marquises, and to the eldest sons of earls: and it is also a title of honour bestowed on those who are honourable by their employments; as lord advocate, lord chamberlain, lord chancellor, &c. LORD'S DAY. All persons, not having a reasonable excuse, shall resort to their parish church or chapel (or some congrega- tion of religious worship allowed by the Toleration Act) on every Sunday, on pain of punishment by the censures of the church, and of forfeiting one shilling to the poor. The hundred are not answerable for robberies on the Lord’s day. No per- son on that day shall serve or execute any writ, process, judgment, &c. except in cases of treason, felony, or breach of the peace, and the service thereof shall be void. LORDS, House of, one of the three estates of parliament, and composed of the lords spiritual and temporal. LORDASIS, in the medical writings, a name given to a distempered state of the spine, in which it is bent inwards, or towards the anterior parts. It is used in opposition to gibbous, or hump-backed. - LOTION, in medicine and pharmacy, is such washing as concerns beautifying the skin, by clearing it of the deformities made by a preternatural secretion. Almost all the lotions advertised for sale as quack medicines, contain much delete- rious matter, such as muriated mercury, and therefore ought never to be had recourse to. LOTTERIES, games of hazard, in which small sums are advanced for the chance of obtaining a larger value. Lotteries are formed on various plans; but in general they consist of a certain number of tickets, which are drawn at the same time, with a corresponding number of blanks and prizes mixed toge- ther, and by which the fate of the tickets is determined. All lotteries, except those established by Act of Parliament, were, in the reign of queen Anne, declared to be public nuisances. LOUGH, or Loch, the former is the Irish, and the latter the Scotch term for lake. See that article. d - LOVE, in a large sense of the word, denotes all those affec tions of the pleasing kind which objects and incidents raise in us; thus we are said to love not only intelligent agents of morally good dispositions, but also sensual pleasures, riches, and honours. But Love, in its usual and more appropriate signification, may be defined “that affection which, being com- pounded of animal desire, esteem, and benevolence, becomes the bond of attachment and union between individuals of the different sexes; and makes them feel in the society of each other a species of happiness which they experience no where else.” - LOW-BELL, in Birding, a name given to a bell, by In ean S of which they take birds in the night, in open champaign coun- tries, and among stubble in October. The method is, to go out about nine o'clock at night in a still evening, when the air is mild, and the moon does not shine. The low-bell should be of a deep and hollow sound, and of such a size that, a man may conveniently carry it in one hand. The person who Car- ries it, is to make it toll all the way he goes, as nearly as may be, in that manner in which the bell on the neck of a sheep toils as it goes on and feeds. There must be also a box made like a large lantern, about a foot square, and lined with tin, 7 N 598 L U M L. U C DICTIONARY OF MECHANICAL SCIENCE. but with one side open. Two or three great lights are to be set in this; and the box is to be fixed to the person’s breast, with the open side forwards, so that the light may be cast for. ward to a great distance. It will spread as it goes out of the box; and will distinctly shew to the person that carries it, whatever there is in the large space of ground over which it extends, and consequently all the birds that roost upon the ground. Two persons must follow him who carries the box and bell, one on each side, so as not to be within the reach of the light to shew themselves. Each of these is to have a hand- net of about three or four feet square, fastened to a long stick or pole; and on whichsoever side any bird is seen at roost, the person who is nearest is to lay his net over it, and take it with as little noise as possible. When the net is over the bird, the person who laid it is not to be in a hurry to take the bird, but must stay till he who carries the light is got beyond it, that the motions may not be discovered. The blaze of the light and the noise of the bell terrify and amaze the birds in such a manner, that they remain still to be taken; but the people who are about the work, must keep the greatest quiet and stillness that may be. Some people are fond of going on this scheme alone. The person then fixes the light box to his breast, and carries the bell in one hand and the net in the other; the net in this case may be somewhat smaller, and the handle shorter. When more than one are out at a time, it is always proper to carry a gun, as it is no uncommon thing to spy a hare when on this expedition. LOWERING, among distillers, a term used to express the debasing the strength of any spirituous liquor, by mixing water with it. The standard and marketable price of these liquors is fixed in regard to a certain strength in them called proof; this is that strength which makes them, when shaken in a phial or poured from on high into a glass, retain a froth or crown of bubbles for some time. In this state, spirits consist of about half pure or totally inflammable spirit, and half water; and if any foreign or home spirits are to be exposed to sale, and are found to have this proof wanting, scarce any body will buy it till it has been distilled again, and brought to that strength; and if it is above that strength, the proprietor usually adds water to it to bring it down to that standard. There is another kind of lowering among the retailers of spirituous liquors to the vulgar, by reducing it under the standard proof. Whoever has the art of doing this without destroying the bubble proof, which is easily done by means of some addition that gives a greater tenacity to the parts of the spirits, will deceive all that judge by this proof alone. In this case, the best way to judge of liquors is by the eye and tongue, and especially by that in- strument called Hydrometer. LOW WATER, the lowest point to which the tide ebbs. See the article TIDE. . - g LOXODROMIC CURve, or SPIRAL, the path of a ship when her course is directed constantly towards the same point of the compass, thereby cutting all the meridians at the same angle. See RHUMB Line. * r LOZENGE, in Heraldry, a four-cornered figure, resembling a pane of glass in old casements. See Her ALDRY. Though all heralds agree, that single ladies are to place their arms on lozenges, yet they differ as to the origin of this privilege. Loze NGE, is also a form of medicine, made into small bits, to be held or chewed in the mouth till they are melted there: the same with what are otherwise called trochisci “troches.” LOZENGES, among jewellers, are common to brilliant and rose diamonds. In brilliants, they are formed by the meeting of the skill and star facets on the bezil; in the latter, by the meeting of the facets in the horizontal ribs of the crown. See FAcets. . • LUBBER, a contemptuous name given by sailors to those who know not the duty of a seaman. & LUBBER's-Hole, is the vacant space between the head of a lower mast and the edge of the top; it is so termed from a suppo- sition that a lubber not caring to trust himself up the futtock shrouds, will prefer that way of getting into the top. LUCIDA, BRIGHT, an appellation used by way of distinction to several stars; as Lucida Corona, Hydrae, Lyrae, &c. - LUCIFER, a name given to the planet Venus, when she appears in the morning before sun-rise. . . insects and zoophytes, molluscuous worms, &c. about twelve genera, all the species of which are luminous; among those we may notice the lampyris, or glow-worm, and LUFF, the order of the helmsman to put the tiller towards the lee-side of the ship, in order to make the ship sail nearer the direction of the wind, hence s - LUFF Round, or Luff a Lee, is the extreme of this movement by which it is intended to throw the ship's head up in the wind, LUFF up, is to bid the steersman keep nearer to the wind. LUFF into a Harbour, is to sail into it close by the wind. A ship is accordingly said to spring her luff when she yields to the effort of the helm by sailing nearer to the wind than she did before. LUFF Tackle, a name given to any large tackle that is not des- tined for a particular place, but may be variously employed as occasion requires. It is generally somewhat larger than the jingle-tackle, although smaller than those which serve to hoist the heavier materials into and out of the vessel, which latter are the main and fore tackles, the stay and quarter tackles, &c. LUGGER, a vessel carrying three masts with a running bow- sprit, upon which she sets lug-sails, and sometimes has top- sails adapted to them. LUG Sail; a quadrilateral sail bent upon a yard which hangs | obliquely to the mast at one-third of its length. These are more, particularly used in the barca-longas, navigated by the Spaniards in the Mediterranean. LUG Sail Boat, a boat carrying sails of the preceding descrip. tion. LUMBAGO, a fixed pain in the small of the back. . LUMBARIS, a name given to the arteries and veins which spread over the loins. - LUMBRICAL, a name given to four muscles of the fingers, and to as many of the toes. LUMBRICUS, the Worm, a genus of animals belonging to the order of vermes intestina. - LUMINARIES, a term employed, by way of eminence, to denote the sun and moon. LUMINOUS, or PHosphorescENT ANIMALs, consist of Insects furnish fire-fly tribes; the fulgora, or lantern-fly; the scolopendra, or centipede ; the fausus spoerocenus ; the elater noctilucus, and the cancer fulgens. Among the worm-class, the principal are the phloas, or pholas, as it is now generally but erroneously denominated, the pyrosoma, the medusa phosphorea, the nereis nocticula, the pennatula, or sea-pen, and various species of the sepia or cuttle-fish. The atmosphere in some parts of Italy appears occasionally to be on fire, in the evening, from the great quantities of one species of the lampyris that throng together. A single individual of the South America fulgora, fixed upon the top of a cane, or other staff, will afford light enough to read by. The streams of light that issue from the elater noctilucus are so strong in the night, that even the smallest print may be read by their lustre. The acudia or lire- fly is of the beetle kind, and inhabits South America. The natives use them instead of candles, putting from one to three of them under a glass. Madame Meiran says, that at Suriucun, the light of this fly is so great, that she saw sufficiently well to paint and finish one of them in her work on Insects. The largest of the acudia are said to be four inches long, and to shine like a shooting star as they fly. They are thence called Lantern-bearers. The pyrosoma, when at rest, emits a pale blue lustre; but when in motion a much stronger light, varie- gated by all the colours of the rainbow. The phloas secretes a luminous juice, every drop of which illuminates, for a length of time, whatever substance it falls upon, or even touches; and the animal, after death, may be preserved so as to retain its luminous power for at least a twelvemonth. The noctilucent nereis often illuminates, by its numbers, the waters it inhabits, to a very considerable extent; and gives so bright a spiendour to the waves, that, like the atmosphere when lighted up by the lampyris italica, they appear as though they were in a full flame. forth, in these different animals, is of a very different charac- The organ from which the luminous matter is thrown ter, and placed in very different parts of the body; sometimes in the head, sometimes in the tail, sometimes in the antennae, sometimes over the surface generally. L: U N L U N 5.99 DICTIONARY OF MECHANICAL SCIENCE. \ longitude. LUMPERS, labourers employed to load and unload a mer- | chant ship when in harbour. . - LUNAR, any thing relating to the moon; thus we say, Lunar Cycle, Lunar Month, Lunar Year, &c. . . . . iºnº distance, in Navigation, a popular term used to indi- cate the following rule of finding the distance of the moon frºm the sum or some fixed star, for the purpose of ascertaining the Take the difference of the apparent altitudes of the moºn and star, or moon and sun, and half the difference of their altitudes; also take half the sum and half the difference of the apparent distance and difference of the apparent altitudes ; then to the log. sines of this half sum and half difference, add the log. cos. of the true, altitudes (as corrected for semi- diameters, refraction, parallax, and differenge, by means of the tables calculated for these purposes) and the complements of og cos. of the apparent altitudes, and take half the Sum; º this half sum . the log. sines of half the difference of the true altitudes, and find the remainder among the log-tºng: which being found, take out the corresponding log. cos. without taking out the arc, which is unnecessary; Lastly, subtract this log. cos. from the log, sine of half the difference of the true altitudes, increased by 10 in the index; and the remainder will be the log, sine of half the true difference. e Thus, for example, let there be proposed the following data, to find the true distances; viz. Apparent dist. ) and G) . . . . . . . . . 51028' 35" Apparent alt. X ’s centre. . . . . . . . 12 39 Apparent alt. G)'s centre. . . . . . . . 24. 48 True alt...... D's centre. . . . . . . . 13 20 42 True alt. . . . . . G)'s centre. . . . . . . . 24 45 57 Apparent altitude of G) . . . . . . . . . . 24 48 Apparent altitude of > . . . . . . . . . ... 12 30 Different apparent altitudes. . . . . . 12 18 True altitude of G) . . . . . . . . . . . . . . 24 45 57 True altitude of D . . . . . . . . . . . . . . 13 20 42 2)11 25 15 # difference true altitude . . . . . . . . 5 42 37} Apparent distance . . . . . . . . . . . . . . 51 28 35 Jifferent apparent altitude . . . . . . 12 18 -*º 2)63 4G 35 -º-º: . . . . . . . . . . . . . . . . . . . . 81 53 17% § SUlúl . . . . . . sm-wº 2)39 to 35 • a s e º e . . . . . . . . . . . . . . 19 35 17: A difference Then by the foregoing rule we have the following compu- iation : Log. sine ........ 31°53' 174".... 97228488 Log. sine . . . . . . . . 19 35 17: .... 9.5253755 Co. log. Cos. . . . . . . 12 30 . . . . 0-0104.185 Log. Cos. . . . . . . . . 13 20 42 . . . . 9°988.1119 Co. log. cos.. . . . . . 24 48 . . . . 0-0420206 Log. COS. . . . . . . . . 24 45 57 . . . . 9°9580990 2)39:2468743 19°6234371 Log. sine . . . . . . . . 5 42 37 . . . . 89978159 Log. tan, of an arch . . . . . . . . . . . . 10'6256212 Corresponding log, cosine. . . . . . . . 9-3625337 Log. sine . . . 9'6352822 * ſº e º e º 'º e & 25 34 54} . - 2 * * True distance.... 51 949 This is the direct method of determining the true distance, independently of any other tables than those of common loga- rithms, and what are found in the Nautical Almanack; but as this is the most laborious operation connected with the longi- tude problem, various other rules have been devised, which by the help of certain tables render the operation much more sim- ple and expeditious; but in a work of this kind, we cannot properly enter upon the problem under that point of view, in consequence of our not having the necessary tables to refer to. The most approved of these rules may be seen by consulting Mackay on the Longitude. LUNARE OS, in Anatomy, is the second bone in the first row of the carpus. It has its name from the Latin, luna, “the moon,” because one of its sides is in form of a crescent. LUNARIA, Satin-flower, or Moonwort, a genus of plants belonging to the tetradynamia class, and in the natural method ranking under the 39th order, Siliquosae. LUNATION, the time between one new moon and another ; : consisting of 29 days, 12 hours, 44 minutes, 3} seconds, LUNE, LUNULA, in Geometry, is the space included between the arcs of two unequal circles, forming a sort of crescent or half moon; the area of which may in many cases be as accu- rately determined as that of any rectilinear figure. The lune was the first curvilinear space of which the quadrature was ascertained, and this is said to have been first effected by Hip- pocrates of Chios; and the figure still bears his name, being commonly denominated the lune of Hippocrates; the construc- tion of which is as follows: On the diameter of a semicircle describe a right-angled triangle, of which the angular point will neces- sarily fall in the circumference. Then on each of the sides A. D., D B, de- scribe a semicircle, and the two figures A G F D, D H E B will be lunes, and the area of them will be . C. Jº, equal to the area of the right-angled triangle A D B. LUNETTE, in Fortification, an enveloped counterguard, or elevation of the earth, made beyond the second ditch, opposite to the places of arms, differing from the ravelins only in their situation. Lunettes are usually made in ditches full of water, and serve to the same purpose as faussebrayes, to dispute the passage of the ditch. See Fortification. LUNETTE, in the Manege, is a half horse-shoe, or such a shoe as wants the sponge, i. e. that part of the branch which runs towards the quarters of the foot. LUNette, is also the name of two small pieces of felt, made round and hollow, to clap upon the eyes of a vicious horse, that is apt to bite, and strike with his fore-feet, or that will not suffer his rider to mount him. LUNGS, in Anatomy, a part of the human body serving for respiration. In the Journal de Medecine for June, 1789, is a description of an instrument for inflating the lungs, invented by M. Gorcy, physician to the military hospital at Newsbri- sach, which appears to be extremely well adapted to the pur- pose, whilst it may be used with the greatest ease and facility. This instrument, which the inventor styles apodopic, that is, “restorer of respiration,” consists of a double pair of bellows. B C LM, fig. 1, the two different parts of which have no com- munication with each other. In the lower side B M is an aper- ture A, for a valve constructed on the principles of those of M“Nairne’s air pump. It consists of a rim of copper, closed at one end by a plate of the same metal, in which plate are seven small holes placed at equal distances. . This plate is covered with pieces of silk coated with elastic gum, in which are six transverse incisions, of two or three lines in length. Bach incision is so made as to be situated between two of the holes, and at an equal distance from each: see D, fig. 2. The silk must be made very secure by a thread passing seve- ral times round the rim. It is obvious, that a stream of air applied to that side of the plate which is opposite the silk, will pass through the holes, and, lifting up the silk, will escape through the incisions. On the contrary, a stream of air applied to the other side will press the silk upon the pkate, and thus close the holes, so that it will be impossible for it to pass through them. This valve opens internally, so as to admit the 600 L U S L Y N DICTIONARY OF MECHANICAL SCIENCE, air from without. At B is another valve, on the same construc- tion, but, opening in a contrary direction, thus permitting the air to escape out of the lower part into the tube EF, but pre- venting its entrance. At C is another valve, opening internally to admit the air from the tube EF; and at D there is a fourth, opening externally to dicharge the air from the upper part. The flexible tube EF, screwed at the end C B, being introduced into one of the nostrils, whilst the mouth and the other nostril are closed by an assistant, if we separate the two handles L. M., which were close together at the introduction of the tube, it is evident that the air in the lungs will rush into the upper part through the valve C, whilst the external air will fill the lower 3-ºxº tº §§ §§ Uº º part through the valve A ; the two handles being again brought into contact, the atmospheric air will be forced into the lungs through the valve B, and at the same time the air in the upper part will be discharged at the valve D. Thus by the alternate play of the double bellows, the lungs will be alternately filled and emptied as in respiration. In using this instrument, care should be taken not to be too violent; as the more perfectly the natural motion of respiration is imitated, the better. To pre- vent any substances from without injuring the valves AD, fig, I, the rim is made with a screw B, fig. 3, in order to receive cap A A, fig. 3, full of º small holes. This screw -º-º-º. -----" " - has also another use. If air, or oxygen gas, be pre- ferred, a bladder, filled with air, fig. 4, may, by means of the screw A, be fastened to the valve A, fig. 1; and, to prevent waste, as this air may serve several times, a flex- ible tube may be screwed on the valve D, fig. 1, com- municating with the blad- der by means of the open- ing d, fig. 4: thus it may be employed as often as - . the operator thinks proper. There is a handle K to the partition in the middle, in order that, if it be at any time necessary to use either of the divisions alone, the other may be confined from acting. c b, fig. 5, represent the two valves to be applied at the end of the instrument c B, fig. 1; and fig. 6, is a section of the end c B, shewing the valves in their proper places. It is proper to add, that the capacity of the instrument should be proportioned to the quantity of air received into the lungs in inspiration, which Dr. Goodwyn has ascertained to be twelve cubical inches, or somewhat more. Each division of the instrument, therefore, should be capable of containing that quantity. - LUPUS, the Wolf, one of the old constellations, lies on the East of Centaurus, with which it is bounded on the North by Scorpio, and on the West by Norma Euclidis; or, anciently, by Ara, the altar. LUSTRAL, an epithet given by the ancients to the water used in their ceremonies to sprinkle and purify the people. From them the Roman church borrowed the holy water. LUSTRATION, in Antiquity, sacrifices or ceremonies by which the ancients purified their cities, fields, armies, or peo- ple defiled by any crime or impurity. , Some of these lustra- tions were public, others private. There were three species or manners of performing lustration, viz. by fire and sulphur, by water, and by air; which last was done by fanning and agita- ting the air round the thing to be purified, LUTE, or Lot ING, among chemists, a mixed, tenacious, ductile substance, which grows solid by drying, and being ap- plied to the juncture of vessels, stops them up, so as to prevent the air from geting in or out. Lute is also a musical instru- ment with strings.-The lute consists of four parts, viz. the table, the body or belly, which has nine or ten sides; the neck, which has nine or ten stops or divisions, marked with strings; and the, head or cross, where the screws for raising and lower- ing the strings to a proper pitch of tone are fixed. In the mid- dle of the table there is a rose, or passage for the sound. There is also a bridge that the strings are fastened to, and a piece of ivory between the head and the neck, to which the other extre- mities of the strings are fitted. In playing, the strings are struck with the right hand, and with the left the stops are press- ed. The lutes of Bologna are esteemed the best, on account of the wood, which is said to have an uncommon disposition for producing a sweet sound. - LUTHERN, in Architecture, a kind of window over the cor- nice, in the roof of a building, standing perpendicularly over the naked part of a wall, and serving to illuminate the upper story. Lutherns are of various forms, as square, semicircular, round, called bull’s eye, elliptic arches, &c. LUXATION, is when any bone is moved out of its place of articulation, so as to impede or destroy its proper office or motion. LYCIUM, a genus of plants belonging to the pentandria class, and in the natural method ranking under the 28th order, Luridae. - . - - LYCODONTES, the petrified teeth of the lupus-piscis, or wolf-fish, frequently found fossile. They are of different shapes, but the most common kind rise into a semiorbicular form, and are hollow within, somewhat resembling an acorn cup; this hollow is found sometimes empty, and sometimes filled with the stratum in which it is immersed. Many of them have an outer circle of a different colour from the rest. LYCOPERDON, a genus of plants belonging to the crypto- gamia class. LYCOPODIUM, or CLUB Moss, a genus of plants belonging to the cryptogamia class. LYCOPSIS, a genus of plants belonging to the pentandria class; and in the natural method ranking under the 41st order, Asperifoliae. LYCOPUS, a genus of plants belonging to the diandria class; and in the natural method ranking under the 42nd order, | Verticillatae. LYING-TO, the situation of a ship when she is retarded in her course by arranging the sails in such a manner as to coun- teract each other with nearly equal effect, and render the ship almost stationary with respect to her head-way: a ship is usu- ally brought-to by laying either her main top-sail or fore-top- sail aback, the helm being put close down to leeward. This is particularly practised in a general engagement, when the hos- tile fleets are drawn up to battle. - LYMPH, a fine fluid, separated in the body from the mass of blood, and contained in peculiar vessels. It is distinguished into watery and coagulable. LYNX, THe, in Astronomy, is one of the northern constella- tions, and was composed by Hevelius out of the unformed stars of the ancients.-Boundaries and Contents: N. by Ursa Major and Camelopardalis, E. by Leo Minor, S. by Cancer and Gemini, and W. by Auriga and Camelopardalis. There are 44 stars in this constellation, whose right ascension, gene- rally, is 115°, and its declination 45° N. The greater part of it, therefore, does not set to the British isles. None of the stars exceed the 4th magnitude, and their positions may be easily | ascertained by reference to the neighbouring constellations. | The Lynx is a paratanellon to Gemini and Cancer. L Y R. L Y T 601 DICTIONARY OF MECHANICAL SCIENCE. ... LYONS, IsrAel, a reputable mathematician, and an excel- lent botanist, was born of Jewish parents in Cambridge, in 1739. He was author of several works, but the only one neces- sary to mention here is his “Treatise on Fluxions,” published in 1758. He was appointed astronomical observer in Captain Phipps's voyage towards the North Pole in 1773; the duties of which office he discharged much to the satisfaction of the. Board of Longitude, by whom he was appointed. His death happened about two years after his return from this WOyage. f - #A, the Harp, one of the northern constellations, which owes its name to the lyre that Apollo gave to Orpheus, and with which he descended into the infernal regions, in search of Euridice. Qrpheus, after death, received divine honours, and his lyre be- came one of the constellations.—Boundaries and Contents: This constellation, situated to the S.E. of the head of Draco, occupies the right angle of a triangle formed by Arcturus, Vega, and the Polar Star on the W.; it is bounded by Hercules S. by E., and E. by Cygnus. Lyra is easily known by Vega, of the 1st mag- nitude, which shines with a splendid white lustre; 3, y, Ö, are also conspicuous stars, of the 2d and 4th magnitudes. Vega, a, having 277°42' 36" right ascension, and 38° 37' 22" north decli- nation, never sets to the British isles, and it culminates as follows: Merid. Alt. 77° 6' 22" N. - MONTH, CULM. MONTH. CULM. MonTH. CULM. ho. mi. -> ho. mi. ho. mi. Jan. 11 54 M. May 3 35 M. Sept. 7 58 A. Feb. 9 32 M. June 1 51 M. Oct. 6 10 A. March 7 40 M. July 11 50 A. Nov. 4 15 A. April 4.45 M. Aug. 9 50 A. Dec. 2 6 A. LYRE, a musical instrument of the stringed kind, much used by the ancients. - Concerning the number of strings with which this instrument was furnished, there is great controversy. Some assert it to be only three; and that the sounds of the two remote were acute, and that of the intermediate one, a mean between those two ex- tremes; that Mercury, the inventor, resembled those three chords to as many seasons of the year, which were all that the Greeks reckoned, namely, summer, winter, and spring ; assign- ing the acute to the first, the grave to the second, and the mean to the third. LY THRUM, Purple Loosestrife, a genus of plants belong- ing to the decandria class; and in the natural method ranking under the 17th order, Calycanthemae. See BotANY. M. M A C M is the twelfth letter of our alphabet. M is also a numeral letter, and among the ancients was used for a thousand. When a dash is added to the top of it, as M, it signifies a thousand times a thousand. M, as an abbreviature, stands for Manlius, Marcus, Martius, and Mucius; M.A. signifies magister artium, or master of arts ; M.S. manuscript; and MSS. manuscripts. M in astronomical tables, and other things of that kind, is used for meridional or southern, and some- times for meridian or mid-day. M.D. medicinae doctor, doctor of medicine. M, in medicinal prescription, is frequently used to signify a maniple or handful; and it is sometimes also put at the end of a recipe, for misce, “mingle ;” or for mixtura, “a mixture.” Thus, m. f. fulapium, signifies “mix and make a julep.” M, in Law, the brand or stigma of a person convicted of manslaughter, and admitted to the benefit of clergy. It is to be burnt on the brawn of his left thumb. MABBY, a species of wine made from potatoes. Some attempts have recently been made to improve its quality, but without much success. It is said to be in use in Barbadoes. MAC, an Irish word signifying son. It is frequently prefixed to surnames, as Macdonald for Donald's son; Maclaurin, for the son of Laurin or Laurence. A. MACAM, in Natural History, the name of an Indian fruit. It is of a round shape, and about the size of our common wild crabs which grow in the hedges. Instead of seeds resembling apples, it has one hard kernel: the taste is unpleasant. The tree is small, and its leaves appear like those of the quince, having somewhat of a yellowish tinge. MACARQNIC, or MACARONIAN, an appellation given to a burlesque kind of poetry, made up of a jumble of words of dif- ferent languages, and words of the vulgar tongue latinized. The Italians are said to have been the inventors of it. The “Germans, French Spaniards, &c. have also had their macaro- nic poets. MAGASSAR Poison, called in matural history, ippo, is the gum of a tree that grows in the isle of Celebes, in the Indian Ocean, with which the Malayans anoint their arrows. MACE, the covering of the nutmeg, that lies between the Outer coat and the shell. It is an unctuous membrane; first of a light red, and afterwards, when dried as we see it, of a yellow- ish hue. After being taken from the shell and exposed to the sun, it is dipped in sea water, or moistened with it, and finally SO *: jied as to allow of its being packed in bales for exporta- + * M A C tion. Mace is liable to seizure, if packed in bales of less than 300 lbs weight. It possesses all the virtues, without the astrin- gency, of the nutmeg. MACERATION, in Pharmacy, an infusion or soaking ingre- dients in water, or other fluid, in order to soften them, and draw out their virtues. MACHINE, signifies anything used to augment or regulate moving forces or powers; or it is any instrument employed to produce motion in order to save either time or force. The word is of Greek origin, and implies machine, invention, art; is there- fore properly applied to any agent, in which these are com- bined, whatever may be the strength or solidity of the materials of which it is composed. The term machine, is, however, gene- rally restricted to a certain class of agents, which seem to hold a middle place between the most simple tools or instruments, and the more complicated and powerful engines; this distinc- tion, however, has no place in a scientific point of view ; all such compound agents being generally classed under the term machines, the simple parts of which they are compounded, being termed MechANICAL Powers. Machines are again classed under different denominations, according to the agents by which they are put in motion, the purposes they are intend- ed to effect, or the art in which they are employed ; as, Electric, Hydraulie, Pneumatic, Military, Architectural, &c. MACHINEs. The maximum effect of machines is the greatest effect which can be produced by them. In all machines, working with an uniform motion, there is a certain velocity and a certain load of resistance, that yield the greatest effect, and which are there- fore more advantageous than any other. A machine may be so heavily charged, that the motion resulting from the applica- tion of any given power will be only sufficient to overcome it, and if any motion ensue, it will be very trifling, and the effect small. Again, if the machine is very lightly loaded, it may give great velocity to the load; but from the smallness of its quan- tity, the effect may still he very considerable, consequently be- tween these two loads there must be some intermediate one, that will render the effect the greatest possible. And this is equally true in the application of animal strength as in ma- chines, and both have been submitted to strict mathematical investigation, the former being founded on numerous experi- ments and observations on the best method of applying animal strength, and the measure of it when applied in different direc, tions. 7 O 602 M A C M A C DICTIONARY OF MECHANICAL scIENCE. ... The maximum effect of a machine is produced when the weight or resistance to be overcome is 3 of that which the power when fully exerted is able to balance, or of that resistance which is necessary to reduce the machine to rest; and the velocity of the part of the machine to which the power is applied, should be one-third of the greatest velocity of the power. The moy- ing power P and the resistance R being both given; if the machine be so constructed that the velocity of the point to which the power is applied be to the velocity of the point to which the resistance is applied, as 9 R is to 4 P, the machine will work to the greatest possible advantage. e This is equally true when applied to the strength of animals; that is, a man, horse, or other animal, will do the greatest quan- tity of work by continual labour, when his strength is opposed to a resistance equal to 3 of his natural strength, and his velo- city equal to 4 of his greatest velocity, when not impeded. .Now according to the best observations, the force of a man at rest is on an average about 70lbs. ; and his great velocity, when not impeded, is about 6 feet per second, taken at a me- dium. Hence the greatest effect will be produced when the resistance is equal to about 31; lbs. and his uniform motion 2 feet per second. tº The strength of a horse at a dead pull is generally estimated at about 420lbs. and his greatest rate of walking 10 feet per second ; therefore the greatest effect is produced when the load = 1863 lbs. and the velocity \, or 33 feet per second. A ma- chine driven by the impulse of a stream produces the greatest effect when the wheel moves with one-third of the velocity of the water. MACHINE for Raising and Lowering Ladders, Scaffolding Poles, &c.—Description. Fig. 1 is a side elevation of the machine, with ladders E on it, ready for raising. A is a drum for the rope F to work on, with a wheel on its axle for the wheel B to work on, turned by the handle 4, fig. 2, C C C C, wheels for the ready conveyance of thc machine. D D, two rollers for the lad- ders to lay on, with guards on each end. E, ladders; from the drum A a rope works over the pulley H, and is fastened on the crook G. The pulley H is hooked on one of the ladder rooms. I is an earth-screw L. to fix the bottom of the ladders, when no le £ ſº 2 - other fastening presents itself; f, a small C - rope to fasten the ladders to the screw I ; 2, 2, the frames, &c. Fig. 2 exhibits an end elevation of the machine. N. B. On the back rails K steps may be fixed, in order to assist the apparatus. - The MACHINE at Marly, being so much celebrated, on account of its magnificence and the multiplicity of its parts, we shall here give some account of it from Gregory's Mechanics. This machine, which was erected by one Rannequin, of the country of Liège, and began tº work in 1682, is situated between Marſy and the village de la Chaussée: in that place the river is barred up, partly by the machine, and partly by a dam which keeps up the water; but that the navigation may not be interrupted, two leagues above Marly a canal has been cut for the passage of boats and barges: there has also been erected (about 30 fathoms from the machine) a contrivance called an ice-breaker, to prevent floating pieces of ice or timber which come down the stream from damaging the machine; and the better to secure the penstocks and the channels in which the wheels | - Fig.2. 2. through the ice-breaker. move, there is a grate of timber, to stop whatever may come The water is raised to its destined height by means of 14 wheels, which serve to work the pumps, by three different stages: first, from the river to a reservoir, at the elevation of 160 English feet above the level of the Seine; then to a second reservoir, 346 feet higher; and from the latter to the summit of a tower, rather more than 533 feet above the river. The breadth of the machine comprehends 14 jets, or water-courses, shut by sluices or penstocks, which are raised and depressed by racks; and in each of these jets is placed a wheel : these wheels are disposed on three lines; in the first, on the side which points up the stream there are seven, six in the second, and only one in the third. The ends of the axle of each wheel go beyond their bearing-pieces, and are bent into a orank, which makes a lever of two feet; and it is to be observ. ed, that the crank which is towards the mountain sucks and lifts up the water of the river, to drive it into the first cistern, and the other crank gives motion to the balances. Six of the wheels on the first line give motion by one of their cranks to an engine of eight pumps, without reckoning the feeder: these engines are compounded of a regulator, at each end of which hangs a square piece of wood, that carries and directs four pistons; the regulator is put in motion by two beams or leaders, one of which lying along, answers to the crank of the wheel and a vertical regulator, and the other hanging down, is united to the same regulator and to the balance. Of the six wheels we have mentioned, there are five which by their other crank give motion to the pumps that work in the cistern of the first lift, by means of horizontal levers and chains that com- municate the motion. The sixth wheel, which is the first towards the dam, moves a long chain that works the pumps of one of the wells of the upper cistern, which is called the cis- term of the great chevalets. Each of the cranks of the seventh wheel of the first line moves a chain which goes to the first cis- term. The six wheels of the second line move, by each of their cranks, a chain that goes to the upper cistern, which (reckoning the chain that comes from the sixth wheel of the first line) makes 13 chains. These chains go over one of the cisterns of the first lift; and five of them at the same time give motion to the pistons of thirty pumps, whilst the other chains go on straight to the upper cistern. Lastly, the wheel, which is on the third line, by each of the cranks, works an engine of eight sucking and lifting pumps, and of itself supplies one conduit | pipe. The seven chains of the wheels of the first line, in going along, work also eight sucking pumps placed a little below the cistern of the first lift, because in that place there are the waters of a considerable spring brought thither by an aque- duct; and these same chains take up that water the second time, to force it by 49 pumps into the upper reservoir, through two conduit pipes of eight inches, and three others of six inches diameter. The thirty pumps of the cistern of the first lift drive their water also through two pipes of eight inches diameter, which carry it into the upper cistern. The water raised at the two cisterns in the way up the hill discharges itself into a great reservoir, and thence, by two conduit pipes, of a foot diameter each, it runs into reservoirs of communication to be distributed into the several wells or little cisterns of the upper cistern, whence it is raised by 82 pumps, through six conduit pipes of eight inches’ diameter, up into the tower which answers to the aqueduct. The eight great chains that go straight to the upper cistern, without moving any engines by the way, work sixteen pumps behind the upper cistern, to bring back into the reser- voir of the said cistern the water which is lost out of the six pipes that go to ſhe tower. The eight engines which suck and lift the water frºm the river contain 64 pumps: the two cis- terns in the way up the hill together contain 79 pumps, and the upper cisterns 82, to which adding the sucking pumps called feeders, and the 8 others which are below the midway cistern, and besides the 16 pumps which we mentioned as placed be- hind the upper cistern, the machine has in all 253 pumps. The basin of the tower which receives the water raised from the river, and supplies the aqueduct, is 610 fathoms distant from the river. The water having run along an aqueduct of 36 arches, is separated into different conduits which lead it to Marly, and formerly conveyed it also to Versailles and Trianon. Such is the mechanisin of the machine of Marly. Its mean M. A. D. M. A. G. 603 DICTIONARY OF MECHANICAL SCIENCE. produce is from 90,000 to 40,000 gallons of water per hour. We say mean produce, because, under certain favourable circum- stances, it raises more than 60,000 gallons per hour. But dur- ing inundations, or when the Seine is frozen, when the water is very low, or when any repairs are making, the machine stops in great measure, if not entirely. The annual expense of the machine, including the salaries of men, &c. is about £9 a day. MACLAURIN, CoLIN, a very celebrated mathematician, was born in Argyleshire, in February 1798. In his 12th year he is said to have made himself master of the first six books of Euclid in a few days without any assistance, having met with the book by accident, and studied as it were for his amusement. —In 1717 he was appointed professor of mathematics in the Marischall college, Aberdeen, and was soon after admitted a fellow of the Royal Society, of which he was a very useful mem- ber. He died in June, 1746, in the 48th year of his age. He was a good as well as a great man, beloved and admired by the great- est geniuses of his time, by Newton, Hoadly, Clarke, Folkes, Earl Morton, &c. MACULAE, in Astronomy, dark spots appearing in the #. faces of the sun, moon, and even some of the planets. *In this sense the maculae stand contradistinguished from the *faculae, which are luminous spots. The solar maculae are of an irregular changeable figure, observed first by Galileo in 1610, soon after he had finished his telescope, and about the same time by Huygens and Hevelius, Mr. Flamstead, Cassini, Kirch, &c. Many of these maculae appear to consist of heterogeneous parts, of which the darker and more dense are called by Hevelius nuclei, and are encompassed as it were with atmo- spheres somewhat rarer, and less obscure, but the figure both of the nuclei and entire maculae is variable. In 1644 Hevelius observed a small thin macula, which in two days extended ten times its bulk, appearing withal much darker, and with a larger nucleus; and such sudden mutations are frequent. The nucleus began to fail sensibly before the spot disappeared, and | before that it quite vanished it broke into four, which in two || Some maculae have lasted fifteen, | twenty, thirty, but seldom forty days; though Kirch observed | one in 1681, which remained from April 26th to the 17th of | July. The spots move over the sun's disc with a motion some- That observed by Kirch was twelve days visible on the sun’s disc; for fifteen || days more it lay behind it, it being usual to return to the limb | any square consisting of an odd number of units, viz. days again re-united. what slower nearer the limb than the centre. whence they departed, in twenty-seven, and sometimes in twenty-eight days. elliptical shape, is produced by the gradual recession of the same spots from the middle or front of the sun's disc to his Various hypo- | edge, by the rotation of this star on its axis. theses have been invented to account for these spots; some considering them as dark clouds floating in the solar atmo- | sphere, others as real excavations, which have not the property | of propagating light as the other parts of this luminary, the depth of some of them having been estimated at more than 4000 miles, and their orifices much exceeding this in diameter; some of them, indeed, from the angle they subtend, must exceed in size the whole globe of the earth. Dr. Herschel has offered some conjectures on this subject, in the Philosophical Transactions for 1795 and 1801; those variations in the state of the weather, in different years, may arise, he thinks, from the greater or less number of maculae on the solar disc. . - - - MADDER, a rough trailing plant, that grows wild in the south of Europe, and is much cultivated in England and Hol- land as a dye-wood for calico printers. The roots afford the dye. But the madder of Smyrna and Cyprus excels for its bright and beautiful red colour. The roots of the plant, after being dug up, are carefully peeled, and dried in an open airy shade, and afterwards in a kiln, in the same way as hops are dried in Kent. The next process, of pulverizing or chopping them, was long a secret with the Dutch ; but we have machines now in Glasgow and Manchester, that do this in the most supc- rior style. . MADREPORA, in Natural History, the name of a genus of submarine substances, belonging to the order Athophytae. MADRIGAL. A short amorous poem of unequal verses, souls. sophy to the production of surprising but yet natural effects. The different figures of the solar spots, varying from the circular form to the respective widths of an || not confined either to the regularity of a sonnet, or to the point of an epigram. A beautiful, noble, and delicate thought, ex- pressed with elegant simplicity, falls under this denomination. . MAGAZINE, a place in which stores are kept, of arms, ammunition, provisions, &c. - MAGAZINE, Powder, ought to be fire and bomb proof; semi- circular, 60 feet within the foundations, being 8 feet thick, and 8 high to the spring of the arch. X- MAGAZINE, Artillery, in a siege, is made about 25 or 30 yards behind the battery, towards the parallels, and at least 3 feet under ground. - - MAGAZINE, is also a term applied to a periodical publication; as, the Imperial Magazine, the Philosophical Magazine, &c. The number of these monthly publications is very great, and the knowledge they diffuse is proportionate to their numbers. MAGELLANIC CLouds, the name given to three perma- ment whitish appearances, resembling the milky way, near the south pole, being distant from it about 11 degrees. MAGI, or MAGIANs, an ancient religious sect in Persia, and other eastern countries, who maintained, that there were two principles, the one the cause of all good, the other the cause of all evil; and, abominating the adoration of images, worshipped God only by fire, which they looked upon as the brightest and most glorious symbol of Oromasdes, or the Good God; as dark- ness is the truest symbol of Arimanius, or the Evil God. This religion was reformed by Zoroaster. The sect still subsists in Persia, under the denomination of Gaurs. MAGIC, originally signified only the knowledge of the more sablime parts of philosophy; but as the magi likewise profess- ed astrology, divination, and sorcery, the term magi became odious, being used to signify an unlawful, diabolical kind of science, acquired by the assistance of the devil and departed Natural magic is only the application of natural philo- MAGIC Square, is a square divided into cells, in which the natural numbers from 1 to the proposed square are so posited, that the sum of each row, whether taken horizontally, vertically, or diagonally, is equal to a certain given number; thus, in the annexed figure, which contains 9 cells, the sum of the numbers in each row is equal to 15. De Lahire gives the following rule for filling up the cells in 4 || 9 || 2 3 || 5 || 7 - - - - -- | 8 || 1 || 6 Place the least term 1, in the cell immediately under the middle or cen- tral one, and the rest of 22 16 || 41 || 10 || 35 || 4 *=º *=mºmº I ºmºmº sºme=sºme ºf sºmeºmºsºms 47 5 23 || 48 17 42 11 29 the terms, in their natural 30 || 6 || 24 || 49 || 1s"| 36|T2 order, in a descending *º-Eº T__ _ _|_|_|_T | diagonal direction, till 13 || 31 || 7 || 25 || 43 || 19 || 37 they run off either at the º- —!—||—||—||—| bottom or on the side. 38 || 14 || 32 || 1 || 26 || 44 | 20 ! When the number runs —|—|—|—|—|—|—| off at the bottom, carry 21 || 39 || 8 || 33 || 2 || 27 45 it to the uppermost cell ——|—|—|—|–|—|—| which is not occupied, of 46 || 15 40 || 9 || 34 || 3 || 28 || the same column that it would have fallen in be- - low, and then proceed, descending diagonally again as far as you can, or till the num- bers either run off at the bottom or side, or are interrupted by coming at a cell already filled. When any number runs off at the right hand side, then bring it to the farthest cell on the left hand of the same row or line it would have fallen in towards the right hand; and when the progress diagonally is inter- rupted, by meeting with a cell already occupied by some other number, then descend diagonally to the left from this cell till an empty one is met with, where enter; and thence proceed as before. This rule, with reference to the above square, will be readily understood by the ingenious reader without further explanation. MAGIC Square of Squares, is an extension given to the magic square, by Dr. Franklin. Here a great square of 256 little squares, in which all the numbers from 1 to 16° or 256, are placed in 16 columns, which, taken either horizontally or ver- 604 M A G M A G DICTIONARY OF MECHANICAL SCIENCE. tically, possess several curious properties, but which we are obliged to omit detailing, for the introduction of more im- portant matter. f . . . $ MAG1c Circle of Circles, is an invention of Dr. Franklin's, founded on the same principles and possessing similar proper- ties to the magic square of squares, by the same author. This consists of eight concentric circles and eight radii, in the cir- cumferences of which all the natural numbers from 12 to 75 are so posited, that the sum of the number in each circumference, together with the central number 12, is equal to 360; and the numbers in each radius, including always the central number, also is equal to 360. Besides the above, these circles possess several other curious properties. The position of the numbers in each radius is as below, beginning with the outward num- ber, and proceeding thence towards the centre, which is always 12, and common to each radius. - 1st rad. 2d rad. 3d rad. 4th rad. 5th rad. 6th rad. 7th rad. 8th rad, 62 73 14 25 30 41 46 57 24 15 72 63 56 47 40 31 71 64 23 16 39 32 55 48 17 22 65 70 49 54 33 38 69 66 31 18 37 34 53 50 19 20 67 68 51 52 35 36 60 75 12 27 28 43 44 59 , 26 13 74 61 58 45 42 29 12 12 12 12 12 12 12 12 Here the successive horizon lines will represent the several circumferences, and the vertical ones the radii, the sums in each being 360. • MAGNA CHARTA, the great charter of the liberties of England, and the basis of our laws and privileges. It was first obtained by the barons, sword in hand, from king John, and was ratified by various subsequent kings. * MAGNESIA. This is a family of minerals which compre- hends all the combinations of magnesia with acids. When freed from extraneous matters, magnesia is a powdery sub- stance of a limpid white colour. Epsom Salts, or Sulphate of MAGNesſ A, consists of magnesia in conjunction with sulphuric acid. It is said, that Epsom salts have been found in the Alps and in Switzerland under a powdery form, and sometimes even in masses, or a state of incrustation on stones and rocks. They are, however, chiefly found dissolved in mineral waters, and particularly in those at Epsom in Surrey and Seidlitz in Bohemia. Their taste is bitter and unpleasant. air, that the Abbé Haüy kept some by him for more than 12 years without any sensible alteration. These salts are much used in medicine, and are sometimes manufactured from the waters of Epsom and Seidlitz, but more frequently and in much greater abundance from sea water. The magnesia of the shops is prepared by dissolving Epsom salts in water, and adding to the solution half their weight of potash. The sub- stance that sinks to the bottom is magnesia; and this, washed with a sufficient quantity of water and dried, has the appear- ance of a light, soft, and white powder, of insipid taste Mag- nesia is used in medicine, both in a simple state and when calcined or burnt. It is also employed in some chemical pro- cesses; and is in considerable request in the manufacture of enamel and porcelain. If putrid water be agitated with a small quantity of magnesia, it will lose a considerable portion of its bad taste and smell. MAGNET, LOAD stone, a ferruginous stone, which is en- dowed with the property of attracting iron, of pointing itself in a certain direction, and of communicating the same property to iron or Steel bars. See MARINER's CoMp Ass. The Poles of a MAGNet, are those points which seem to possess the greatest power, or in which all the virtue appears to be concentrated. The Magnetical Meridian, is a vertical circle in the heavens, which intersects the horizon in the points to which the magnetic needle when at rest directs itself. The 4a is of a Magnet, is a right line which passes from one pole to another. The Equator of a Magnet, is a line perpendicular to the axis, and exactly between the poles. The distinguishing and characteristic properties of a magnet are as follows:–1. Its attractive and repulsive power. 2. Its So little are they affected by exposure to the . directive power. 3. Its dip or inclination to a point above or , below the horizon. 4. Its power of communicating its own properties to certain other bodies. • . º Phenomena of the Magnet.—These are numerous, but some of the principal are as follows:–1. A magnet, when freely sup- ported by a thread, or in a light vessel on water, will place itself in a direction nearly coinciding with the poles of the earth. 2. This direction of the needle is not the same in all parts of the world, nor in the same place at different times. 3. A needle, not magnetized, being exactly balanced, will, if touched by a magnet so as to communicate that property to it, have its equilibrium destroyed, one of its extremities dipping considerably below the horizontal plane. 4. The centres of action of a magnet are at a small distance from its extremities, and the law of attraction from these centres is reciprocally as the squares of the distances. 5. When a magnetic needle is put out of its natural line of direction, the force with which it tends to regain that position varies as the sine of the angle subtended by its natural direction and that in which it is placed. 6. In every magnet there are two poles, of which the one points northwards, the other southwards; and if the mag. net be divided into any number of pieces, the two poles willº. be found in each piece. The poles of a magnet may be found 4 by holding a very fine short needle over it, for where the poles are, the needle will stand upright, but no where else. . Thus, in fig. I, of the horse-shoe magnet, N indicates the north, and S the south pole of the magnet. By the following method also, the situation of the poles, and the direction of the (supposed) magnetic effluvia passing out of the stone, may be exhibited :-Strew about the poles of the stone on every side, iron or steel filings on a sheet of white paper; these small par- ticles will be affected by the effluvia of the stone, and be so disposed as to shew the course and direction of the magnetic particles in every part. Thus, fig. 2, in the middle of each pole, Fig. 1. Fig. 2. it appears to go nearly straight on; towards the sides it pro- ceeds in lines more and more curved, till at last the curve- lines from both poles exactly meeting and coinciding, form numberless curves on each side, nearly of a circular figure. A small artificial magnet may be used in this experiment, instead of the real magnet, with a similar effect, if the table on which the paper rests receives a few gentle knocks, so as to shake the filings a little, otherwise the action of the magnet will not be sufficient to dispose properly those particles which lie at a considerable distance. # - 7. These poles, in different parts" of the globe, are differently inclined towards a point under the horizon. 8. These poles, though contrary to each other, help mutually towards the mag- net's attraction, and suspension of iron. 9. If two magnets be spherical, one will turn or conform itself to the other, as either of them would do to the earth; and after they have so con- formed or turned themselves, they have a tendency to ap- proach or join each other; hut if placed in a contrary position, they repulse each other. 10. If a magnet be cut through the axis, the segments or parts of the stone, which before were joined, will now repel each other. 11. If the magnet be cut perpendicular to its axis, the two points which were before. conjoined, will become contrary poles; one in the one, and one in the other segment. 12. Iron receives virtue from the mag- net by application to it, or barely from an approach towards it, though it do not touch it; and the iron receives its virtue variously, according to the parts of the stone, it is made to touch, or even approach to. 13. If an oblong piece of iron be any way applied to the stone, it receives virtue from it only lengthways. 14. A needle touched by a magnet will turn its M. A. C. M. A. G. 605 DICTIONARY OF MECHANICAL SCIENCE. end the same way, towards the poles of the world, as the mag- net itself does. 15. Neither the magnet, nor needles touched by it, conform their poles exactly to those of the world, but have usually some variation from them; and this variation is different in different places, and at divers times in the same places. 16. A magnet will take up much more iron, when armed or capped, than it can alone. 17. A strong magnet at the least distance from a smaller or a weaker, cannot draw to it a piece of iron adhering actually to such a smaller or weaker stone; but if it touch it, it can draw it from the other: but a weaker magnet, or even a small piece of iron, can draw away or separate a piece of iron, contiguous to a larger or stronger magnet. 18. In north latitudes the south pole of a magnet will raise up more iron than its north pole. 19. A plate of iron only, but no other body interposed, can impede the operation of the magnet, either as to its attractive or directive quality. 20. The power or virtue of a magnet may be impaired by lying long in a wrong position, as also by rust, wet, &c. and may be quite destroyed by fire, lightning, &c. 21. A wire being touched from end to end with one pole of a magnet, the end at which you begin will always turn contrary to the pole that touched it; and if it be again touched the same way with the other pole of the magnet, it will then be turned the contrary way. 22. If a piece of wire be touched in the middle with º: the pole of the magnet, without moving it backwards or rwards, in that place will be the pole of the wire, and the two ends will be the other pole. 23. If a magnet be heated red-hot, and again cooled, either with its south pole towards the north, in a horizontal position, or with its south pole down- wards in a perpendicular position, its poles will be changed. 24. Hard iron tools well tempered, when heated by a brisk attrition, as filing, turning, &c. will attract thin filings, or chips of iron, steel, &c. and hence we observe that files, punches, augres, &c. have a small degree of magnetic virtue. 25. The iron bars of windows, &c. which have stood a long time in an erect position, grow permanently magnetical; the lower ends of such bars being the north pole, and the upper end the south pole. 26. Tongs and fireforks, by being often heated, and set to cool again, in a posture nearly erect, have gained this magnetic property. Sometimes iron bars, by long standing in a perpendicular position, have acquired the mag- netic virtue in a surprising degree. A bar about ten feet long and three inches thick, supporting the summer beam of a room, was able to turn the needle at eight or ten feet distance, and exceeded a loadstone of three pounds and a half weight; from the middle point upwards it was a north pole, and down- wards a south pole. 27. A needle well touched, it is known, will point nearly north and south; but if it have one contrary touch of the same stone, it will be deprived of its faculty, and by another such touch it will have its poles interchanged. 28. A magnet acts with equal force in vacuo as in the open air. The smallest magnets have usually the greatest power in proportion to their bulk. A large magnet will seldom take up above three or four times its own weight, while a small one will often take up more than ten times its weight. A magnet worn by Sir Isaac Newton in a ring, and which weighed only 3 grains, would take up 746 grains, or almost 250 times its own weight. A magnetic bar made by Mr. Canton, weighing 10 oz. 12 dwts, took up more than 79 ounces; and a flat semi- circular steel magnet weighing 1 oz. 13 dwts. took up an iron wedge of 90 ounces. - Armed MAGNet, denotes one that is capped, cased, or set on iron or steel, to make it take up a greater weight, and also more readily to distinguish its poſes. The magnet in this case is mounted with two pieces of iron, which are called the armature. The figure represents an armed magnet, where A B is the loadstone; CD, CD, are the armature, or the two pieces of soft iron, to the projec- tions of which, D, D, the iron weight E is to be applied. The dots E, L, d. L. d, represent the brass box, with a ring at E, by which the armed * may be suspended. Artificial MAGNet, is a bar of iron or steel impregnated with the magnetic ſluid, and possessing all the properties of the mag- net itself, and commonly in a much higher degree. There are various methods of communicating the power of a magnet to bars of iron and steel, whereby these last become themselves magnets, and capable of again transmitting their power to others, and so on. There are also several ways of making artificial magnets without the assistance of any magnet what- ever. Procure a dozen bars, six of soft steel and six of hard; the former to be each three inches long, + of an inch broad, and the 20th of an inch thick, with two pieces of iron, each half the length of one of the bars, but of the same breadth and thickness, and the six hard bars to be each 5% inches long, an inch broad, and ºths of an inch thick, with two pieces of iron half the length, but the whole breadth and thickness, of one of the hard bars; and let all the bars be marked with a line quite round them at one end. Then take up an iron poker and tongs, or two bars of iron, the larger they are and the longer they have been used, the better; and fixing the poker upright between the knees, hold to it near the top, one of the soft bars, having its marked end downwards, by a piece of sew- ing silk, which must be pulled tight by the left hand, that the bar may not slide; then grasping the tongs with the right hand a little below the middle, and holding them nearly in a vertical position, let the bar be stroked by the lower end from the bot- tom to the top, about ten times on each side, which will give it a magnetic power sufficient to lift a small key at the marked end, which end, if the bar were suspended on a point, would turn towards the north, and is therefore called the north pole; and the unmarked end is for the same reason called the south pole: four of the soft bars being impregnated after this man- ner, lay two of them parallel to each other, at one-fourth of an inch distance, between the two pieces of iron holding them, a north and south pole against each piece of iron; then take two of the four bars already made magnetical, and place them together so as to make a double bar in thickness, the north pole of one even with the south pole of the other; and the remaining two being put to these, one on each side, so as to have two north and two south poles together, separate the north from the south poles at one end by a large pin, and place them perpendicularly with that end downwards on the middle of one of the parallel bars, two north poles towards its south end, and the two south poles towards its north end; slide them three or four times backward and forward the whole length of the bar; then removing them from the middle of this bar, place them on the middle of the other bar, as before directed, and go over that in the same manner; then turn both the bars the other side upwards, and repeat the former operation; this being done, take the two from between the pieces of iron, and placing the two outermost of the touching bars in their stead, let the other two be the outermost of the four to touch these with ; and this process being repeated till each pair of bars have been touched three or four times over, will give them a con- siderable magnetic power. Put the half dozen together after the manner of the four, and touch them with two pair of the hard bars placed between their irons, at the distance of about half an inch from each other; then lay the soft bars aside, and with the four hard ones let the other two be impregnated, holding the touching bars apart at the lower end near two- tenths of an inch; to which distance let them be separated after they are set on the parallel bar, and brought together again before they are taken off: this being observed, proceed according to the method described above, till each pair has been touched two or three times over; but as this vertical way of touching a bar will not give it quite so much of the magnetic virtue as it will receive, let each pair be now touched once or twice over, in their parallel position, between the irons, with two of the bars held horizontally, or nearly so, by drawing at the same time the north end of one from the middle over the south end, and the south of the other from the middle over the north end of a parallel bar; then bringing them to the middle again without touching the parallel bar, give three or four of these horizontal strokes to each side. The horizontal touch, after the vertical, will make the bars as strong as they pos- sibly can be made, as appears by their not receiving any addi- tional strength, when the vertical touch is given by a great 7 P 606 M A G M. A. G. DICTIONARY OF MECHANICAL SCIENCE, number of bars, and the horizontal by those of a superior magnetic power. - This whole process may be gone through in about half an hour; and each of the large bars, if well hardened, may be made to lift twenty-eight Troy ounces, and sometimes more. And when these bars are thus impregnated, they will give to a hard bar of the same size its full virtue inless than ten minutes; and therefore will answer all the purposes of magnetism in navigation and experimental philosophy, much better than the loadstone, which has not a power sufficient to impregnate hard bards. The half dozen, being put into a case in such a man- ner as that no two poles of the same name may be together, and their irons with them as one bar, they will retain the vir- tues they received; but if their power should, by making experiments, be ever so far impaired, it may be restored with- out any foreign assistance in a few minutes. And if perchance a much larger set of bars should be required, these will com- municate to them a sufficient power to proced with ; and they may in a short time, by the same method, be brought to their full strength.-Barlow, Phil. Tran. To illustrate the magnetical inclination or dip of the needle, take a globular magnet, or, which is more easily procured, an oblong one, like S. N. in the figure; the extremity N, of which is the north pole; the other extremity, S, is the south pole, and A is the middle or equator; place it horizontally upon a table CD, then take another small oblong magnet, as, viz. a bit of steel wire, or a small sewing needle magnetized, and suspend it by means of a fine thread tied to its middle, so as to remain in an horizontal position when not disturbed by the vicinity of iron, or other magnet. Now, if the same small magnet being held by the upper part of the thread, be brought just over the middle of the large magnet within two or three inches of it, the former will turn its south pole s, towards the north pole N of the large magnet, and its north pole n towards the south pole S of the large one. It will be farther observed, that the small magnet, while kept just over the middle of the large one, will remain parallel to it; for since the poles of the small magnet are equally distant from the contrary poles of the large magnet, they are equally attracted. But if the small magnet be moved a little nearer to one end than to the other of the large magnet, then one of its poles, viz. that which is nearest to the contrary pole of the large magnet, will be inclined downwards, and of course the other pole will be elevated above the horizon. It is evident that this inclination will increase according as the small magnet is placed near to one of the poles of the large one, because the attraction of the nearest will imave more power upon it. If the small magnet be brought just opposite to one of the poles of the large magnet, it will turn the contrary pole towards it, and will place itself in the same straight line with the axis of the large magnet. - This simple experiment will enable the reader to comprehend easily the phenomena of the magnetic inclination, or of the dipping needle upon the surface of the earth; for it is only necessary to imagine, that the earth is a large magnet, (as it in fact appears to be,) and that any magnet, or magnetic needle commonly used, is the small magnet employed in the fore- going experiment. The direction of the dipping needle in any place is called the magnetic line. The best shape of a magnetic needle is repre--wºmmºnummumns. sented in these two figures, the first of which shews the upper side, and the second shews a lateral view of the needle, which is made of steel, having a pretty large hole in the middle, to which aeonical piece of agate is adapted by means of a brass piece 0, into which the agate is fixed. The apex of this hollow cap rests upon the point of a pin F, which is fixed in the centre of the box, and upon which the needle, being properly balanced, turns very nimbly. For common purposes, these needles have a conical perforation made in the steel itself, or in a piece of brass, which is fastened in the middle of the needle. - The dipping needle, though of late much improved, is how- ever still far from perfection. The general mode of comstruct- ing it is, to pass an axis quite through the needle, to let the extremities of this axis, like those of the beam of a balance, rest upon its supports, so that the needle may move itself ver- tically round, and, when situated in the magnetic meridian, it may place itself in the magnetic line. The degrees of inclination are shewn upon a divided circle, in the centre of which the needle is suspended. This figure repre- sents a dipping needle of the simplest construction :-A B is the needle, the axis of which FE rests upon the middle of two lateral bars CD, CD, which are made to the frame that contains divided circle A.I. B. K. This machin fixed on a stand G, but when used at it is suspended by a ring H, so as to h perpendicularly. When the instrum is furnished with a stand, a spirit level - is generally annexed to it, and the sta has three screws, by which the instrument is situated, so th the centre of the needle, and the division of 90 on the lowe part of the divided circle, may be exactly in the same time perpendicular to the horizon. - An Account of the Experiments of Peter Barlow, of the Ro º Military Academy, on the Magnetism induced or exhibited in Iron and other Metals by rotation. Availing himself of one of the turning lathes, in the royal arsenal, an attempt was made by this gentleman to ascer- tain whether, by giving to an iron body a rapid rotation, any change could be distinguished in its magnetic state during the motion, or after it had subsided; accordingly, a small howitzer shell was attached to a lathe, admitting of a rapid motion, and a small compass being placed very near to it, it was perceived at once that the needle was con- siderably deflected, but it returned to its original direction as soon as the motion ceased. A thirteen-inch shell was then fixed to the mandrel of one of the large lathes worked by the steam engine, and the effect obtained was of course propor- tionably greater. In fact, with this shell, the direction of the needle was, in many cases, reversed by the motion of the for- mer; but there were other points in which no motion could be observed." - Moreover, in several instances the deviation of the nee- dle was made in a contrary way to what it was in others, varying in quantity as stated above, from zero to 180°, accord- ing to the situation of the needle; the distance and the rate o- motion being the same. In all cases, by reversing the motion of the shell, the deviation was reyersed also ; so that if with the shell turning one way, the needle-deviated to the esst, it devia- ted to the west when the shell was turned in an opposite direc- tion; and in all cases during the rotation of the shell, the nee- dle preserved its deviating direction remarkably steady, viz. without any kind of oscillation or tremor; but the moment the motion ceased, it returned to its original and true bearing. The effect produced was therefore temporary, and depended entire- ly on the velocity of rotation. - - These were all the deductions of any importance drawn from the first series of experiments; and as the steam-engines were not set to work again for some time, no farther obser- vations were made, till Mr. Barlow, finding himself embar- rassed with the iron work of the lathes and other machines, had an apparatus constructed, which he erected on his own pre- mises, and by means of which he at length succeeded in deducing the laws which regulate and determine the direction of the needle in all cases, and in all situations. The results have been presented to the Royal Society, and the fol- lowing concise account of them may be acceptable to our readers:– º M A G M. A. G. 607 DICTIONARY OF MECHANICAL SCIENCE. This apparatus con- sists of a frame, a a, resembling that on K. which the cylinder of an electrical machine is H hung; the ball B sup- plying the place of the cylinder, the diameter of the ball or shell was eight inches, and its weight about 30 lb. A - strong table c cee, fixed with its feet into the ground, the floor of the r room being cut away - --- so as to prevent any c shaking of the floor or c walls. The diameter ºf of the larger wheel D = \ - as 18-inches; of the tº aller E, three inches; nd the handle F might be turned with ease twice in a second, hich gave about 720 revolutions per minute to the shell. A tand G, made heavy by being loaded with sand, had a small latform H attached; it might be brought up close to the shell, nd the suspended compass H, surrounded by a glass tube K, placed near the same, at any azimuth, and on either side. Moreover, there were several holes in the table, which enabled the experimenter to screw down the frame itself in any azi- muth, by means of the fly nuts 11. The ball could only revolve with its axis horizontal, but it could be made to revolve direct or reverse at pleasure. The platform might be depressed or raised to any height, and the needle thus placed over or under any proposed point of the shell. Things being thus prepared, the platform was first placed in the horizontal plane of the ball's axis, and the needle placed successively at every point all round. And it appeared that whatever might be the azimuth of the needle, (provided it was neutralized by the magnet, L, from the directive power of the earth,) on turning the ball, the north end of the needle approach- ed towards it when the motion was towards the ... but receded when the motion was from the needle. That is, when the upper part of the shell, by the revolution, descended towards the needle, the north end of the needle approached towards the shell; but when the ball revolved in an opposite direction, then the south end of the needle approached, or the north end receded. When the needle was carried round the shell in a vertical circle, ascending 10° each time, the following results were ob- served, (the needle being in every case neutralized, and placed parallel to the axis of rotation,) viz. from the horizon to an altitude of about 54°, the needle placed itself perpendicularly to the axis of the north end, passing the contrary way to that in which the motion of the shell was made ; from 54° to 90°, or to the zenith of the ball: the needle also placed itself perpendicu- larly to the axis, but in a rºyersed position to what it took up before, viz. the north end passed in the direction of motion in the shell. It did the same on the other side of the vertical, to a like point or altitude of about 549; but from that point to the horizon it arranged itself as at first. Below the horizon it also preserved the same direction till it amounted again to 54°; it then changed its direction, as when above the horizon. There were, therefore, four points of change in the direction of the needle, (the motion of the ball remaining the same,) viz. at 54° above and below the horizon of the ball, on each side of the zenith and radius. It will of course be understood, that by reversing the motion of the ball, the needle also changed its direction, but the points of change remained the same; and that the effect was independent of the direction of the axis of motion, viz, whether the axis was east and west, north and south, or in any other azimuth; but it required a certain velocity, not less than 600 revolutions per minute, to produce the full effect. It is obvious, therefore, that the mere rotation of an iron shell im- presses, upon it, during the motion of the same, a temporary magnetic effect, and that this effect ceases the moment the motion is discontinued. The above experiments were begun in December, 1824; and it was not till April 1825, that Mr. Barlow learned that M. Arago had been making similar experiments in France, on cop- per and other metals, without being aware of their actual date. They were not known in England till Gay Lussac's visit to London at the time above stated. e are not aware of the precise nature of these experiments, and shall, therefore, only endeavour to describe those which Mr. Maish assisted Mr. Bar- low in making, and which he founded on the description he had received. They may, therefore, be considered as the experi- ments of M. Arago, repeated and varied as different circum- stances occurred, to suggest new ideas. The account he had of | M. Arago's experiments, was, that by placing a copper plate upon a vertical spindle, the plate being horizontal, and then placing just above it a light compass needle, but independent of course of the plate, or causing the spindle and plate to re- volve, the needle was considerably deflected, and more and more as the velocity was increased, so that when the plate was put into rapid rotation, the needle also began after a few vibra- tions to revolve, and at length with considerable velocity. 1. In order to repeat this experiment, says Mr. Maish, I con- nected the wheel of my turning lathe with a vertical spindle, which I could make revolve forty-five times per second; and on this I placed a thin copper plate, about six inches diameter, and over this a needle about five inches long shut up in a close box, about one inch or rather less above the plate. When putting the lathe in motion, I found it to deflect the needle about five points, the deflection being always in the same direc- tion as the motion of the plate, but we could not cause it to re- volve. The needle was therefore partly neutralized by a bar magnet, and the experiment repeated. We then very soon ob- tained a considerable rotatory motion in the needle; and by using a larger and heavier plate, the same was produced after- wards without neutralizing the needle. 2. Another experiment, which was mentioned as one of M. Arago's, and which I repeated, was by interposing a plate of iron between the copper plate and the needle. In this case no effect could be produced on the needle by the rotation of the copper plate, the iron clearly intercepting the action. 3. I now tried a zinc plate instead of a copper plate, and the effect was nearly the same as before, but a little less. 4. An iron plate was now substituted, and the effeet was con- siderably greater than with the copper-plate. 5. The copper plate was again replaced, and a brass needle placed in the box. Some motion was obtained, but it was very equivocal, so that I cannot venture to say that it was cer- tainly due to the rotation. - 6. A heavy horse-shoe magnet was now suspended by a line from the ceiling, and it was put in rotation by the revolution of the copper plate—a paper screen having been first interposed between them. 7. One copper plate was suspended over another, but no mo- tion was obtained, and the same took place when the copper plate was suspended over an iron one. 8. A bar magnet rather shorter than the diameter of the cop- per plate was fixed horizontally to the upright spindle, and being made to revolve, the plate very soon acquired rotation. A paper screen was in this, as in the preceding experiments, interposed between the plate and magnet. 9. The plate was now applied immediately to the axis of the lathe, so as to cause it to revolve vertically, and the needle placed near to it, but no motion took place, till, by nearly neu- tralizing the needle, and bringing either of its poles directly to the plate, it then always deviated in the direction of the motion of the plate, whichever pole of the needle was directed to the former; the needle of course, therefore, deviated different ways, (all other things being the same,) when it was above or below the axis, but in the direct horizontal line of the axis no motion in the needle took place, 10. The above are the principal experiments that I assisted in making by revolving the plate, but these having suggested to Mr. Barlow that all the results obtained might be explained by supposing that there existed a slight magnetic power in copper, and in the various metals, which had a tendency to draw the needle after the plate, or the latter after the former, he endea- voured to exhibit this by direct experiment, independent of 608 M. A. G. M. A. G. - DICTIONARY OF MECHANICAL SCIENCE. volution. With this view, he neutralized a needle very accu- rately; and then applying very near to its poles the end of a round brass ruler, the attraction of the latter was obvious—it drew the needle several degrees, then, withdrawing it, and catching the needle again in its returning vibration, it was drawn out some farther-degrees, and in a very short time the deflection was converted into a revolution, which, by alternately presenting and withdrawing the brass ruler, was at length ren- dered very rapid. 11. The same result was obtained by two or three different pieces of brass; but there were other pieces, although of the same size and form, which had little or no effect. The following experiment is due to Mr. Sturgeon of Wool- wich. 12. A thin copper plate or wheel, about five or six inches in diameter, was suspended very delicately on an axis, and then on one side a little weighted, in order to give it a tendency to oscillate. The heavy point was now raised level with the axis of the plate, opposite to the heavy point was placed a qua- drant divided from zero to 90 degrees, the number of vibrations the plate made before it came to 45 degrees was counted. The same was again done, with this difference only, that the vibra- tions now took place between the poles of a strong horse-shoe magnet, and the number of them before the plate fell to 45 de- grees, was very little more than one half of what they were in the former instance. This is the converse of M. Arago's experiments, in which he shews the effect of copper, and other metallic rings, in dimi- nishing the number of oscillations of a magnetic needle. 13. If, instead of a horse-shoe magnet, the contrary pole of two bar magnets be used, the effect is the same as before: but if the poles of the same name, viz. both north or both south, be employed, then the effect is scarcely perceptible. This is an important result, as it shews that the effect is not due to any kind of resisting medium, as was supposed in the first instance. The analogy subsisting between electricity and magnetism, the identity of lightning and electricity, and their effects in destroying the polarity of the magnetic needle, and in some cases reversing its poles, while in other instances lightning has communicated the magnetic power to pieces of steel that had not before any polarity, are facts well known. Various attempts have been made to establish the identity of electricity and magnetism by means of the galvanic battery, till Pro- fessor Oersted, of Copenhagen, in the year 1820, succeeded in demonstrating their reciprocal action on each other, by the most decisive and satisfactory experiments. The galvanic batteries, generally used for the illustration of electro-magnetism, have been considered by Mr. Sturgeon as cumbersome and inconvenient, and he has succeeded in con- structing one, which is neither expensive, cumbersome, nor difficult to manage. Yet with this small battery (which will only hold about half a pint of fluid) he was enabled to exhibit the whole train of electro-magnetic experiments. Sturgeon's battery consists of two concentric copper cylin- ders, having a common bottom ; they are about six inches in depth, and the outer one two inches diameter; between these is placed another cylinder of zinc without a bottom, insulated by three pieces of cork from the copper; two wires proceed from the zinc part of the arrangement, one supporting a small cup, the other bent downwards (and the like from the copper part) for the purpose of forming the various connexions necessary to make the experiments. The batteries themselves are attached to a wire fixed in a block of wood (forming a stand) by two gudgeons, one of which has a screw by which it can be fixed at any height required. The apparatus for producing the deflection of the magnetic needle is represented in fig. 1. The wire proceeding from the zinc extremity of the battery being placed to the north, and the other end placed in the cup A, attached to the wire passing above the needle C, it was deflected to the west; and when the wire was placed in the cup B, connected with the wire passing below the needle, its deflection was towards the east. The needle with which this experiment was performed was eight inches long, half an inch wide, and nearly a quarter of an inch thick, and it was deflected from the plane of the magnetic meridian in an angle of from 60 to 70 degrees, upon completing the galvanic circuit. Prth balls were attached to the poles of the magnet, as in the figure, to render the deflection more visible to the spectators. M. Arago's experiment of magnetizing a piece of iron, was erformed with the apparatus represented in fig. 2. By com: ºleting the galvanic connexion, the piece of iron AB, contained Fig. 1. Fig. 2. within the spiral wire C, inserted in the cups d and e, beca strongly magnetic, and attracted or repelled another magne according as dissimilar or similar poles were presented. Its attractive power was very great, as its extremities supported two pieces of iron f and g, of several ounces weight, which on breaking the contact fell on the lecture table precisely as the lecturer had predicted. The bottoms of the cups are con- nected by a wire passing under the board upon which they are placed. The beautiful apparatus for effecting the revolution of the galvanic wire about the magnet is here exhibited. The two upright pillars A and B are the legs of a horse-shoe magnet, concealed by brass cylindrical cases, the bottom of the magnet being inserted into a block of wood which forms a pedestal; the cups C and D, which are four inches in diameter, con- taining the mercury, are at- tached to two caps of paste- board, e and f, which are made to fit the tops of the pil- lars; when the communica- tion was made by connecting the zinc end of the battery with the cups i and k, and the copper extremity with the cups l and m, the wires g and h began to revolve very ra- pidly round the poles of the magnet in contrary directions. This was made very conspi- cuous by the pith balls fixed to the wires. The advantage of employ- ing large magnets in prefe- rence to small ones, in produ- cing electro-magnetic pheno- mena, is well known. Many experiments are usually made, for the purpose of ascertaining whether any definite proportion between the galvanic and magnetic forces is essential to the production of the greatest effect; and it has been found, that the galvanic force might be reduced almost to any degree, provided the magnetic power is sufficiently great. This discovery has led to the use of powerful magnets, and small galvanic batteries. Barlow's plate for neutralizing the action of the iron of ships in producing a deviation in the compass, is as follows, and for which discovery the board of longitude gave this gentleman £500:-The centre of a small circular iron plate is placed on the line of the attraction of the ship's iron, and at a proper distance behind and below the pivot of the compass needle, the position of this line having been ascertained previously to the ship's leaving port, an operation which will be greatly M A G *- M. A. I 609. DICTIONARY OF MECHANICAL SCIENCE. N facilitated by a table for this purpose prepared by Mr. Barlow. When this is done, the needle will remain active and vigorous in the polar regions, and will direct itself in the true magnetic meridian, in whatever part of the world the ship is placed. This effect of the invention has been experimentally established between the 61° of south latitude and the 81° of north latitude, by the accurate observations of Lieutenant Foster, and by other naval officers. There are few scientific inventions of modern times more useful in practice than this. Scoresby's New Experiments on Magnetism, are as follows:– Bars of steel could be rendered highly magnetic by hammering them in a vertical position, with the lower end resting upon a poker or rod of iron. This process, however, he has greatly improved by hammering the steel bars between two bars of | iron : the steel bars were the eighth part of an inch in diame- ter. When only one bar of iron was used, a steel wire six inches long lifted a nail weighing 186 grains; but when two bars of iron were used, the wire lifted 326 grains. When the new process was employed with an iron bar eight feet long, a steel wire six inches long lifted 669 grains, or four times its The theory of the process is, that percussion on .9wn weight. tº sº º tºi. substances in mutual contact inclines them to an • * £ * # equality of condition, in the same manner as all bodies of * different temperatures tend to assume the same temperature ** when in contact. ſº tical by position, the interposed bar of steel will therefore, | The two great iron bars being made magne- when thrown into a state of vibration by percussion, receive a portion of their magnetism. In like manner a magnet, when struck in the air with a piece of flint, or upon a body of inferior magnetic quality, will have its magnetism diminished. MAGNETISM, ANIMAL, a pretended mode of curing all kinds of disease by means of a sympathetic affection between the sick person and the operator. Towards the conclusion of the 18th centary, this scientific nostrum made a considerable noise in England, but soon fell into dispute. On the continent its life was a little more protracted, but in most places contempt arrested its progress, and oblivion became its grave. In Germany some few persons still affect to treat it with venera- tion, but its credit is irrecoverably lost, its boasted effects having been clearly traced to excited imagination. MAGNIFYING, is used to denote the apparent enlarge ment of an object by means of a convex lens, or some other optical instrument, particularly the microscope. See LENS, MICRO- sco PE, TELEscoPE, &c. º MAGNIFYING Glass, is a popular term for any convex glass or lens which has the property of magnifying. MAGNITUDE, is used to denote the extension of any thing, whether it be in one direction, as a line; in two direc- tions, as a surface; or in three directions, which constitute a body or solid. - - Geometrical MAGNITU des, may be conceived to be generated by motion, as a line by the motion of a point, a surface by the motion of a line, and a solid by the motion of a surface. Apparent MAGNITUDE of a body, is that which is measured by the angle which that body subtends at the eye ; at least, this is what is always to be understood by this expression in the science of optics, though in reality the apparent magnitude depends not only on the visual angle, but also upon the sup- posed distance of the object we are viewing. The mind judges of the magnitude of distant objects on two principles, viz, with reference to the optic angle, and the distance of the object from the eye, the latter arising out of our experience, which shews that distance diminishes that angle; and therefore, without being aware of the deduction, we always make a cer- tain compensation agreeably to the supposed distance. If we see a man, or any other known object, at a distance, it conveys to our mind the idea of a certain magnitude, which we attri- bute to it entirely independent of the angle which it subtends; but if the object is unknown, then both the distance and the angle are considered, in forming an idea of its magnitude : it is thus that we sometimes deceive ourselves with regard to the size of an object, if we are mistaken as to its distance; thus, a small bird on the branch of a tree may appear to be a larger bird at a greater distance, or the contrary; thus also a fly im- perfectly seen in the corner of window, may have the appear- ance of a crow flying in the open air; these are optical illusions which commonl y happen, and which most persons accustomed to observation, recollect to have experienced at one time or other. . It is on this principle, that some writers have accounted for the different apparent magnitudes of the sun and moon, and the apparent distance of two or more known stars, when seen near the horizon, and when they have a greater angle of eleva- tion. When we see the moon, fortexample, at a considerable elevation, there being no intervening objects between that luminary and the eye, where with to make a comparison of its distance, we intuitively suppose it nearer than when we observe it in the horizon; because there are then numerous objects, many of them at great distances, and the moon being evidently beyond them all, we thence suppose its distance greater than in the former case, and the optic angle being still nearly the same, we attribute to it a greater magnitude in the horizon than in the zenith, because we suppose its distance then to be the greatest: hence also the apparent figure of the heavens, which instead of having the form of a perfect concave hemisphere, the eye being in the centre, it has always the appearance of being considerably flattened in the upper part, or being a segment considerably less than a hemisphere. This however is a sub- ject that has much engaged the attention of astronomers and philosophers, from the earliest period to the present time; and various hypotheses have been advanced to account for it, none of which are perhaps perfectly satisfactory. - MAGNOLIA, the laurel-leaved tulip tree, a genus of plants belonging to the polyandria class. The flower of the magnolia is very magnificent, being a fine white, and of large dimensions. This tree loves a southern aspect, and requires to be well matted up during the severity of our winter. MAHOGANY. The Suietània Mahagoni, or mahogany-tree, is a native of the warmest parts of America, and grows also in the islands of Cuba, Jamaica, Hispaniola, and the Bahama islands. This tree grows tall and straight, rising often sixty feet from the spur to the limbs; and is about four feet in diame- ter. The foliage is a beautiful deep green, and the appearance made by the whole tree very elegant. The flowers are of a red- dish or saffron colour, and the fruit of an oval form, about the size of a turkey’s egg. Some of them have reached to a size exceeding one hundred feet in height. The mahogany-tree thrives in most soils, but varies in texture and grain according to the nature of the soil. On rocks it is of a smaller size, but very hard and weighty, and of a close grain, and beautifully shaded; while the produce of the low and richer lands is more light and porous, of a paler colour, and open grain; and that of mixed soils holds a medium between both. This wood is generally hard, takes a fine polish, and is found to answer bet- ter than any other sort in all kinds of cabinet ware. MAHOMETANS, believers in the doctºgnes and divine mis- sion of Mahomet, the celebrated warrior and pseudo-prophet of Arabia. The religion of Mahomet is divided into two general parts, faith and practice. The fundamental article of the Maho- metan creed is contained in this one confession : There is but one God, and Mahomet is his prophet. Under these two proposi- tions are comprehended six distinct branches, viz. belief in God, in his angels, in his scriptures, in his prophets, in the resurrec- tion and judgment; or in God’s absolute decrees, or predesti- nation. They reckon five points relating to practice, viz. pray- er with washings, &c. alms, fasting, pilgrimage to Mecca, and circumcision. Mahomet admitted the divine mission of both Moses and of Jesus Christ. Mahometism is a borrowed sys- tem, made up for the most part of Judaism and Christianity; and, if it be considered in the most favourable point of view, might possibly be accounted a sort of Christian heresy. Ach- met Benabdalla, in his letter to Maurice Prince of Orange, says, “The Lord Jesus Christ is held by us (Mahometans) to be a prophet, and the messenger of God, and our lady, the Virgin Mary his mother, to be blessed of God, holy, who brought him forth, and conceived him miraculously by the almighty power of God.” MAIDEN, in ancient English customs, an instrument for beheading criminals. It was in form of a painter’s easel, about ten feet high; at four feet from the bottom was a cross bar, on which the felon laid his head, which was kept down by another placed above. In the inner edges of the frame were grooves : in these were placed a sharp axe, with a vast weight of lead # 7 Q 610 M A L M. A. L. I) ICTIONARY OF MECHANICAL SCIENCE. supported at the summit with a peg; to that peg was fast- ened a cord, which the executioner cutting, the axe fell, and severed the head from the body. This instrument is said to have been introduced into Scotland by the Regent Morton, who himself was afterwards executed by it. This apparatus is now in possession of the society of Scottish Antiquaries. But there is reason to believe it was known in Scotland prior to the time of Morton coming into power, for they shew, in the armoury at Aberdeen, the maiden with which Sir John Gordon was executed in the time of Queen Mary, after the defeat and death of his father the earl of Huntly, at Corrichie. In France, criminals have been put to death by the maiden or guillotine, since the horrible revolution.— Maiden, is also the name of a machine for washing linen, in Yorkshire. MAIHEM, or MAIM, signifies a corporal wound or hurt, by which a man loseth the use of any member. MAIM, in Law, a wound by which a person loses the use of some member that might have been a defence to him, and this crime is felony, by 22 and 23 Charles II., without benefit of clergy, though no such attainder shall corrupt the blood, or occasion forfeiture of lands, &c.—Cutting and Maiming is also, by a recent statute, felony. . - - MAIN, an epithet applied to whatever is principal, as opposed to what is inferior or secondary; thus, the main land is uscd in contradistinction to an island, and the main mast, the main wale, the main keel, and the main hatchway, are in like manner distinguished from the fore and mizzen masts, the channel wales; the false keel, and the fore and after hatch- ways. MAIN Tackle, a large and strong tackle, hooked occasionally. on the main pendant, and used for various purposes, particu- larly in securing the mast, by setting up the rigging, stays, &c. See the article PEND ANT. MAINPRIZE, a writ directed to the sheriff, commanding him to take sureties for a prisoner's appearance, (when the offence is bailable, or when the cause of commitment is not properly bailable “below,”) and to set him at large. These sureties are termed mainpernors, and they can neither impri- son nor surrender their man, as “bail,” so called, can, but are barely sureties for his appearance at the day. MAINTENANCE, in Law, nearly the same as Barretry, being an officious intermeddling in a suit that no way belongs to one, by maintaining or assisting either party with money, or otherwise, to prosecute or defend it. This is an offence against public justice; though a man may with impunity main- tain the cause of his relation, kinsman, servant, or poor neigh- bour, out of charity. . . * * MAISE, or INDIAN CoRN, is a species of grain much culti- vated in America and other countries: the grains are yellow when ripe, flat-shaped, like pressed pease, and grow in a sort of knot round the top of the plant. These plants are sown in March, April, or May, and usually yield two crops a year, at the rate of from 15 to 40 bushels per acre. Maise might, with advantage, be cultivated in England. MAJESTY, a title given to kings. MAKING-UP, among distillers, the reducing spirits to a certain standard of strength, usually called proof, by the admix- ture of water; which should be either soft and clear river wa- ter, or spring water rendered soft by distillation. . MALACHITE, amineral, the green carbonate of copper, found frequently crystallized in long slender needles; colour green, specific gravity about 3.6. There are two varieties, the fibrous and the compact; the constituent parts are, copper 580; car- bonic acid 18.0; oxygen 12:5; water 11'5. MALACIA, in Medicine, a languishing disorder, incident to pregnant women, in which they long at one time for one kind of food, at another for some other kind of food, which they will eat with extraordinary greediness. MALACOLITE, a mineral found in the silver mines in Swe- den and Norway. It is obtained massive, and crystallized in six-sided prisms. Specific gravity 3.25. It consists of silica 53; lime.23; magnesia 19; alumina 3; oxide of iron, &c. 4. MALACOPTERYGEOUS, in Ichthyology, an appellation given to fishes having the rays of their fins bony at the extre- mities, but not pointed, like those of acanthopterygeous fishes, or thorn-backs. n - - | MALATES, in Chemistry, salts formed by the union of the malic acid with different bases. The malates of potash, soda, ammonia, lime, and barytes, may be formed by dissolving these alkalies in malic acid, and evaporating the solution. . , ' , MALE, among zoologists, that sex of animals which has the part of generation without the body. The term male has also been applied to several inanimate things: thus we say a male- flower, a male-screw, &c. - ; : * : MALIC AcID, is found in the juices of a great many fruits, and it derives its name from its being obtained in great abun- dance from apples; it is composed of oxygen, hydrogen, and carbon. . MALICE, in Ethics and Law, a design formed for doing mischief to another, In murder, it is malice that constitutes the crime; termed, in an indictment for murder, malitia prae- cogitata, or malice prepense. r ... " MALLEABLE, a property of metals, whereby they are capa- ble of being extended under the hammer. * * MALLET, a wooden hammer, used by artificers who work with a chisel, as sculptors, masons, and stone-cutters, whose mallets are commonly round ; and by joiners, carpenters, &c.; who work with square-headed mallets. * MALT, a term applied to grain which has been made to ger- minate artificially to a certain extent, after which the process is stopped by the application of heat. See KILN. - The brightness of malt liquor depends much on the accuracy with which the yeast produced by fermentation is separated ; and the usual method of effecting this is the following:—The wort, after being duly boiled with the proper quantity of hops; is transferred into coolers, and when its temperature has there- by been sufficiently lowered, it is removed to a large vessel, called the gyle-tun, either open or fitted with a moveable cover; Here, after being mixed with yeast, it undergoes the first fer- mentation. The half-fermented liquor is then put into barrels lying on their sides, with the bung-hole uppermost, out of which the yeast is continually discharging itself, till the fermen- tation has ceased or nearly so. During this time the barrels . are examined once, twice, or oftener in the day, and are filled up with fresh liquor in proportion as the yeast works off, so that the barrels shall be always full, in order that the yeast, as soon as it rises to the surface of the liquor, shall flow off entirely. - * a * > If the whole of the fermentation were conducted in the barrel in which the beer is stored, and at the same time a method was adopted for the escape of the yeast without the constant attention and expense of filling up, as commonly practised, we should then place the barrels upright, and having filled them with the wort previously boiled and cooled, and mixed with the proper quantity of yeast, adapt to each barrel the following apparatus : . - *— e This apparatus consists of a tub c c, about the size of a peck measure, with a wooden cover ee, and having a vertical open pipe of pewter b, passing through the bottom; this pipe rises nearly to the top of the tub, and, almost as soon as it has pass- ed through the bottom, expands into a broad flat margin, in order that it may be placed securely over the bung-hole of the barrel a a, with paper packing if required. Into the tub is put' liquor of the same kind as that with which the barrel is filled, except that it is not previously mixed with yeast; the quantity of the liquor (about one-twelfth) is such as will be rather more M A L M A L 611 DICTIONARY OF MECHANICAL SCIENCE. than sufficient to supply the loss in the barrel in consequence of the fermentation. As soon as this process begins, the yeast, rising to the surface of the liquor in the barrel, passes through the bung-hole into the pewter-pipe, and flows out of the upper end of it into the tub, the lighter particles in the state of froth floating on the surface of the liquor, and the heavier ones sub- siding to the bottom. The vacuity occasioned by the separation of the yeast is continually supplied from the clear Hiquor in the tub, which flows in through the lateral hole d, in the vertical pipe. By the adoption of the above described apparatus, we may save about one and a half per cent. in quantity, and have the quality of the liquor also considerably improved, besides avoiding the use of the gyle-tun, and the expense and loss of transferring the liquor therefrom to the barrels, and the loss of liquor in filling up according to the usual mode. MALT Liquor. Madame Gervais's Improved Brewing Appara- tus.—Presuming that the attention of the intelligent part of the public may be directed to the subject of brewing, by the notice of a new method of conducting part of that process, which ap- peared in several periodical publications, it becomes in some , measure necessary to elucidate it. This cannot be effected bet- ... ter than by Dr. Birkbeck’s judicious abridgment of the pamphlet ‘ describing Madame Gervais’s improved brewing apparatus. “I shall not at present,” says Dr. Birkbeck, “advert to the conversion of barley into malt, or the artificial formation of sac- charine matter by incipient vegetation, but shall begin with the infusion or decoction; that is to say, with the fluid obtained by immersing the bruised malt in hot water, or by exposing it to the action of that fluid when in a state of ebullition. It is next the object of the brewer to convert this fluid, holding mucilagi- nous and saccharine matter in solution, into wine, in the same manner as the must, or expressed juice of the grape, is rendered winous. The curious process of fermentation is accordingly instituted, by adding a little yeast or ferment, by elevating the temperature, and by slight motion with free exposure to the atmosphere. But before the fluid to be fermented is supposed to be complete, so contradictory often are our opinions and practice, the hop must be added, that particular ingredient by which fermentation is to be arrested, or at least the subsequent formation of acetous acid be prevented. And although one practical brewer has shewn, more than twenty years ago, that much of the virtue, or, chemically speaking, of the essential oil, of the hop, is dissipated by heat, and I have pointed out to se- veral persons engaged in brewing, the inconsistency of adding the hop before the first stage of fermentation is finished, yet little has been done in the way of improvement in these respects. To discover when the first stage of fermentation, the vinous, is complete, much attention is required: of the various methods proposed for determining the point, not one can be pronounced to be either sufficiently accurate or sufficiently easy of application; and accordingly it does hap- pen, both in making beer and wine, that before they are en- closed in casks or bottles, so as to put an end to any further change, vinegar has begun to be formed ; or the alcohol, the first product, has became converted into acetic acid, the second, and the article been rendered unfit for the end first intended. In reference to this difficulty, the new method of managing the fermentation possesses very great advantages. Requiring less heat at the commencement, and liberating less caloric in its progress, on account of the limited supply of oxygen gas, or rather, being left without any oxygen excepting what itself con- tains, fermentation will go on more slowly, and must be re- stricted to a certain point; so that it will become exceedingly difficult to produce any acetic acid. Besides, as the whole of the carbonic acid gas which is generated, must pass through the tube proceeding from the side of the cone, and the water, four inches in depth, in which it terminates, the cessation of the escape of air bubbles, which will be easily noticed, will mark unequivocally the conclusion of the fermentative change. Thus a greater quantity of alcohol will be formed, because, without any risk, the fermentation may be permitted to become com- plete, in the liquid wherein it occurs. Such part of the spirit too, as might-fly off during the progress of this spontaneous in- ternal change, will be condensed in the conical cover, kept cool by the water which surrounds it, and will be returned through the small pipe to the fluid below, together with the oily particles * from the hop, evaporating and condensed in the same manner, provided the practice should still be continued, of introducing this ingredient before the fermentation is concluded. It will at once appear obvious that this plan is equally applicable to the manufacturing of wines, and has indeed, I understand, been employed successfully by Messrs. Bishops and Harrington, eminent British wine makers in the neighbourhood of Finsbury square. It will be not less obvious likewise, that the improve- ments now described are-fitted for the service of the private brewer and wine maker, not less than for the very extensive manufactories, because to small vats, backs, or fermenting ves- sels, the conical cap, (with the air-tight condition of the appa- ratus,) can be applied most effectually. To distillers, this ar- rangement may become peculiarly serviceable, as it will enable them to allow fermentation to continue in the wash, as it is termed, which they prepare, without any danger of its becoming . Sour, to an extent, and with a degree of perfection as to the quantity of alchohol produced, which they might not otherwise be enabled to accomplish.” The pamphlet commences with the following appropriate and judicious remarks on the subject of vinous fermentation, and proceeds to describe the patent apparatus, and expatiate on its merits with candour and impartiality, as will be seen by the extracts we have made, for the purpose of communicating to the public, a clear and explicit description of the process. “There is scarcely a single production of the earth, which, when appropriated to the use of man, is not so modified or changed by various preparations, as to possess a different pro- perty from that it contained in its primitive state. Fruit and grain undergo decomposition, and a new recomposition, before he uses them as food; and until he applied art to the juice of the grapes, they were suffered to decay on the vines—but which the ingenuity of man converted into a pleasant, wholesome, and lasting beverage. In those climates where the only substitutes for wine were milk or water, the inhabitants are indebted to his invention for malt liquor, a beverage, which, although infe- rior to wine, is not destitute of some of those qualities that render it so great a desideratum. - “The phenomena by which these new properties are produ- ced, is termed the vinous fermentation; it might, perhaps with more propriety, be called the alcoholic or spirituous fermenta- tion, since it is a process by means of which all saccharine mat- ters, whether they proceed from grapes, sugar-cane, or malt, are decomposed, and recombine to form alcohol. But however wrong this denomination may be, we shall make use of it in the following observations, as being well understood by all classes. Avinous fermentation, to be perfect, requires very exact propor- tions of mucilage and saccharine matter, so as to have the one just sufficient to destroy or attenuate the other; in which case the result would be, if the operation had been properly conducted, a mixture of alcohol and water, differently flavoured, according to the materials from which it was produced, as grapes, pears, apples, or malt and hops ; but such accuracy in the proportions cannot be expected either from nature working at large, and every climate, soil, and situation, or from short-sighted man acting mechanically, and frequently in ignorance of what he is doing. A perfect fermentation, therefore, has been considered an object almost impossible to be obtained ; and all we wish to shew is, that the errors of the mixture may be corrected, and the whole process improved, by good management. “The common practice, until a few years back, has been to ferment in open vessels; and though it was a circumstance well known among chemists, that a certain portion of spirit and flavour escaped in the form of vapour during the process, yet no one had an idea that the condensatory system could be applied ; as it appeared impossible to effect the fermentation in air-tight vessels, being unable to surmount the great difficul- ty which existed of keeping down and managing that enormous bulk of non-condensible gases, which are emitted during the de- composition of the saccharine matter, and which acquire great- er expansive force by the gradual increase of heat. The idea, however, occurred to Madame Gervais, a proprietor of consi- derable vineyards near Montpellier, who has founded a system on the following principle ; that what is termed the winous fer- mentation is a mild, calm, and natural distillation; which, ac- cording to the usual acceptation of the word, has proved a cor- ** f 612 M. A. L. M. A. L. DICTIONARY OF MECHANICAL SCIENCE. rect system, since not a single drop of spirit is formed before it commences, nor after it is over. Having first laid down this ground-work, she proceeded to obtain an apparatus, that would operate in such a manner as to return into the vessel the spirit and flavour that was evolved from the fermenting gyle, and let out the non-condensible gases which might, by the increasing heat, acquire too great an expansive force, and burst the work- ing tun; a short description of this apparatus will be a fresh proof that the greatest advantages are often derived from the most simple means. It consists of a vessel resembling the head of the ancient still, and constructed of such form as to be ca- pable of being placed securely on the back or vat, in which the process of fermentation is to be carried on ; the back or yat must be closed air-tight, with a hole in the top, communicating with that part of the apparatus called the cone or condenser. This cone is surrounded by a cylinder or reservoir, which is to be filled with cold water, so that the alcoholic vapour or steam evolved during the process, may be condensed as it comes in contact with the cold interior surface of the cone; and being thereby converted into liquid, trickles down the inside of the condenser, and through a long pipe is returned into the fer- menting liquor." “By the application of this apparatus, a considerable por- tion of alcohol, which has been hitherto suffered to escape in the form of vapour, along with the non-condensible gases, is con- densed, and returned into the liquor; and the non-condensible gases are carried off by a pipe, which, proceeding from the interior lower part of the cone, and running up to the inside of the cylinder in the cold water, passes out through the side, and the end is immersed some depth below the surface of water contained in a separate vessel, permitting the gases to escape, but still under a certain degree of pressure, the object of which is, to confine the alcoholic steam and gas within the cone, and allow them a sufficient time to cool and condense,” References to the Engraving.—AA, closed vat in which the process of fermentation is carried on. B condensing cone, º communicating immediately with the interior of the fermenting wat. C C, small channel extending round the interior base of the cone, for the purpose of receiving the condensed alcohol and essential oils, which are conducted down the small tube D into the vat. EE, reservoir for containing cold water surround- ing the cone. F, exit-pipe communicating with the interior of the cone, its extremity being immersed some inches below the surface of the water in the small tub G, from which the non- condensible gases are permitted to escape into the atmosphere. H, cock to draw of the water from the reservoir, E. E. “To persons in the least acquainted with chemical opera- tions, it would be useless to dwell on the merits of this appa- ratus; they will at once see how beneficial it would prove to any liquid that has to undergo the vinous fermentation in any stage of its manufacture; but to those who are not so conversant in the principles and causes of these operations, we shall pro- ceed to point them out. “To obtain a good fermentation, as complete a decomposi- tion of the must or wort, and as perfect a recomposition of al- cohol as possible, are the great objects to be obtained. To ac- quire the former, three requisites are necessary; fluidity, heat, and motion: the latter, density, coolness, and tranquillity. Let us examine each of them separately : first, of fluidity. The specific gravity of the liquid most elligible to produce a good fermentation, is between 1.020, and 1-140; or eighteen for one hundred and thirty-two pounds, by Dicas's improved sac- charometer made by Joseph Long, No. 20, Little Tower-street, London. Below eighteen pounds of real extract per barrel, the liquid is too thin to produce a proper fermentation, and above one hundred and thirty-two pounds it is too thick; but supposing the specific gravity of the must or wort to be correct, it may be carried beyond a proper dilation by too much heat, or congealed to too great a consistency by excessive cold; con- sequently, either a thunder storm or hard frost will derange the operation, and are equally injurious to fermentation. Any method therefore that will ensure an even temperature, must be of great importance: and such a method is obtained by apply- ing the apparatus already described, since, by preventing the access of atmospheric air, the sudden changes of the external temperature can have no effect upon the fermenting gyle: and if it has been pitched at a proper heat, (which is between sixty- five and eighty,”) will proceed through its different stages, as well during the hottest days of summer, as in the selected months of autumn and spring. “With respect to motion, we are indebted to Monsieur Gay Lussac, an able French chemist, for a beautiful and important experiment, proving that must, possessed of all the requisites to produce a good fermentation, will not begin to ferment unless excited by a foreign agent. He placed the must in a close ves- sel, from which the atmospheric air had been exhausted, where it remained several days without giving any signs of fermenta- tion, from which he concluded some power was wanting to break the union of its constituent principles; he therefore introduced a small quantity of oxygen, which immediately caused the must to ferment, evidently proving the necessity of a small portion of atmospheric air, (which contains oxygen,) to allow the fermentation to commence. But it at the same time proves, that, after performing that office, this great enemy to all fermented liquors may be dispensed with, without imped- ing the process; as the small quantity of oxygen introduced by Monsieur Gay Lussac, was soon absorbed by the carbon to form carbonic acid gas, and he found no occasion for any fur- ther supply. “This discovery is of the greatest importance, since it en- ables us, without the least detriment or inconvenience to the process, to exclude the oxygen of the atmospheric air, which by constantly supplying the gyle with the principle that causes and promotes acidity, casts on it from the first that roughness and disagreeable flavour which spoil most of our common be- verages. Here again the new apparatus proves of infinite be- nefit; for as soon as carbonic acid gas is evolved from the fer- menting gyle, the atmospheric air being lighter, is driven out from the upper part of the working-tun, and as no air is per- * Formentation will take place from forty-eight to one hundred and thirty- eight degrees. M A L M A M 613 DICTIONARY of MECHANICAL scIENCE. mitted to enter afterwards, all the subsequent carbonic acid gas emitted diminishes the quantity of oxygen contained in the gyle by the oxygen uniting with the carbon as fast as it dis- unites from the saccharine matter during its decomposition, and thereby secures a soundness and peculiar mildness not to be procured by any other mode. “Having stated the necessary conditions for a complete de- composition of the saccharine matter, we shall proceed to no- tice those required for a good production of alcohol. The first already mentioned is a certain density, in order to allow the several principles which are flisunited to recombine. It is doubtful whether such a combination will in any case take place, until the temperature of the gyle having attained its greatest heat, is afterwards cooled a few degrees: a fact con- firming which is, that a portion of the liquid taken out when at its greatest heat, and tried by distillation, produced little or no spirit; but such refrigeration must not be effected too suddenly, as it might coagulate the yet undecomposed mu- cilage, and check its further action on the remaining saccha- rine matter; and by arresting that natural operation, which ought to be pursued a longer or shorter period according to the specific gravity of the fermentable matter, might produce that result termed RoPINess, by holding in solution the coagu- lated mucilage. “Here again the apparatus will be found of great service; for by frequently renewing the cold water in its reservoir, the internal temperature will gradually diminish by the heat of the gyle coming in contact with the cold interior of the cone; but in order to effect this, the tranquillity above mentioned is ne- cessary, since the continual motion is caused by the oxygen soliciting new combinations with the carbon, and thereby con- stantly giving rise to a fresh supply of heat. . The writer then replies very satisfactorily to some objections which have been urged against the adoption of the patent ap- paratus, and shews it applicable, not only to the process of brewing malt liquors, but to the manufacture of wine, cider, perry, and vinegar. We shall now conclude with the following observations: The great advantages to be derived from this system are, excluding the atmospheric air, by which the acid principle which beer absorbs from the air during fermentation, is prevented entering into combination with it, and thereby insuring the brewer the certainty of making as sound beer dur- ing the hot weather as in winter: also the essential oil of the hops and the spirit, which escape on the old principle, are con- densed, and returned immediately into the beer, thereby pre- serving an uniform flavour at all times. In addition to the pre- servation of flavour, strength, and soundness, and enabling the brewer to insure his beer, an increase of five per cent. is gained in the quantity, not only by condensing the alcoholic vapour, but by the yeast settling in a solid body, at the bottom of the tun, so that the beer may be drawn off clear to the last, and the yeast will be left in good condition for pitching with ; likewise, the waste occasioned by the old system of cleans- ing will be prevented, and the beer will retain the fixed air in it, according to the resistance placed at the end of the escape- pipe, and a considerable saving of labour attend it. Upon the new system, the fermentation may be brought to a perfect state at any period, according to the degree of heat made use of for fermentation ; for as long as there remain any particles of saccharine matter in solution undecomposed, so long will the beer continue to increase in strength, arising from the decomposition of these particles, and which can only be promoted by their dilatation with a high fermentation heat; but when the whole of the saccharine matter is decomposed, and as perfect a fermentation as possible obtained, attenuation will be complete, and the beer will precipitate perfectly bright, there being no longer any carbonic acid gas generated to stir up the grosser particles of the fermented matter. Upon the old sys- tem of fermentation, beer can seldom be kept until it has at- tained a perfect state of attenuation; for as the decomposed particles of saccharine matter yield the basis of spirit, so also they yield the basis of acidity; and the beer having already absorbed too large a portion of that principle, an increase of attenuation is generally accompanied with a great increase of acidity. The flavour of beer, on the old system, depends upon the fermentation-heat, as the greater the heat in the tun, the larger is the quantity of essential oil evaporated, with a conse- quent loss of flavour; therefore to insure a good flavour, a low fermentation is necessary, and the lower the fermentation, the longer the saccharine matter is before it decomposes; whereas, on the new system, the whole flavour and strength are preserv- ed, and any degree of heat may be employed to accelerate the fermentation, and bring the beer to an early attenuation. MALT Distillery, the converting fermented liquors into a clear inflammable spirit, which is either sold for use in the common state of a proof strength, or rectified into spirits of wine, or made into compound cordial waters. MALTA, KNIGHTs of, or HospitaLLERs of St. John of Je- rusalem, a religious military order, whose residence was in the island of Malta. The order consisted of three estates, the knights, chaplains, and servants at arms. The government of the order was partly monarchical and partly aristocratical : the grand master being sovereign, none were admitted into this order but such as were of noble birth. - MALTHA, in Antiquity, a cement of which there were too sorts, native and factitious: one of the latter consisted of pitch, wax, plaster, and grease. Another kind, used by the Romans in their aqueducts, was made of lime slacked in wine, incorpo- rated with melted pitch, and fresh figs. Native maltha, called also sea-wax, is a solid substance, found on the lake Baikal, in Siberia. It is white, melts when heated, and, on cooling, assumes the consistence of white cerate. It has also been found on the coast of Finland. MAMALUKES, the line of a dynasty that reigned in Egypt. The Mamalukes were originally Turkish and Circassia; slaves, bought of the Tartars by Melicsalah, to the number of a thou- sand, whom he bred up to arms, and raised some to the princi- pal offices of the empire. They killed Sultan Moadam, whom they succeeded. The mamalukes were skilful horsemen. Their numbers were kept up by the purchase of fresh slaves, and so they continued for many centuries, ruling Egypt in the name of the Grand Signior of Turkey, until the conquest of Egypt by Buonaparte. They then retreated into Nubia, and in 1811 they were decoyed into the power of the Turkish pacha, and slain. MAMMA, from Mamma, the fond word for Mother. This word is said to be found for the compellation (word of salu- tation) of Mother, in most languages, and is therefore supposed to be the first syllables that a child pronounces. MAMMALIA, is properly a branch of Natural History, and indicates the first class of the animal kingdom, containing those animals which suckle their young. Several scientific and ingenious arrangements of the animal kingdom into classes, . orders, genera, and species, have been successively adopted; that of Monsieur Cuvier, the French anatomist, possesses a high degree of merit. . But though his arrangement evinces great anatomical precision, and the highest philosophical know- ledge of animals, yet, to a general reader, it has a. complicated and forbidding appearance, and is less attractive than the more simple arrangement of Linnaeus, which divides the ani- mal kingdom into six classes; mammalia, aves, am hibia, pisces, insecta, vermes: or, such as suckle their young; birds; creatures living equally on land or in the water; fishes; insects; and worms. Each of these classes is subdivided into orders, genera, species, and varieties of those species. These classes are thus arranged for conciseness: Viviparous.... 1. Mammalia. } Oviparous . . . .2. Birds. With lungs....3. Amphibia. With gills.....4. Fishes. Have antennae 5. Insects. Have tentacula 6. Worms. CLASSES. Hot blood With vertebrae - - - - Cold red blood. . } # Without vertebrae. . Cold white blood } The class mammalia, consists of such animals as produce living offspring, and nourish their young with milk supplied from their own bodies; it comprises both the quadrupeds and whales. Their head is the seat of the principal organs of sense, the mouth, the nose, the eyes, and ears. . & Touching or feeling. The outside of the skin is covered with a thin pellicle, called the epidermis, cuticle, or scarf-skin. Under the euticle, is the rete mucosum. In negroes, this substance is black; in Europeans, white, brown, or yellow. The cutis vera, or the skin, is a substance made up of fibres closely connected 7 R 614 M A N M A M DICTIONARY OF MECHANICAL SCIENCE. with each other, and running in various directions, being com- posed of the extremities of numerous vessels and nerves. The papilla of the fingers or inside of the hand, may become erect or elevated, and being gently pressed against a tangible body, receive an impression which is conveyed to the brain, and is called touch. Spiders, flies, and ants, have this sense in the greatest perfection. .. - Tasting. The tongue is covered with two membranes; the external is thick and rugged, especially in quadrupeds; the internal membrane is thin and soft, and upon it appear papillae, or small elevations, like the tops of the small horns of snails. These papillae are composed of the extremities of the nerves of the tongue, and piercing the external membrane, are constantly affected by those qualities in bodies, which have their tastes excited in the mind by means of these nervous papillae, which are the immediate organ of tasting. This organ bears a strong analogy io the sense of touch. - Hearing. The undulations of the atmosphere, excited by the vibrations of somorous bodies, are collected in the external ear and auditory passage, as in the hearing trumpet, and are conveyed to the membrana tympani, or drum, which they cause to vibrate. The effect is transmitted through the small bones, to the watery fluid that fills the internal ear, in which the deli- cate filaments of the auditory nerve float, and by this nerve the sensation is conveyed to the brain. But it is remarkable how nicely is the ear constructed in various animals; in man its position and form are admirably contrived for his erect pos- ture; in quadrupeds we see it large, susceptible of easy motion, as when the horse lays his ears back or points them forward; in the mole it is lodged deep in the head. The structure of the ear is also remarkable, for it is so contrived and tunnelled that it may not only catch sounds, but prevent the more furious un- dulations of the air from injuring the interior membrane. And to prevent insects from lodging within its cavity, as well as to keep it moist and in tune, it is supplied with a bitter nauseous Wax. - - Smelling. The cavity of the nose is divided into two parts, called the nostrils, by a partition, of which the upper part is bony, and the lower cartilaginous. The upper part of the cavity is covered with a thick glandulous membrane, above which the olfactory nerve is finely branched out and spread over the membrane of the spongy bones of the nose, and other sinu- ous cavities of the nostrils. The odorous effluvia of bodies being disseminated in the atmosphere, the latter ſluid passes through the nose in respiration, and the odorous particles are thus brought into contact with the fibres of the nerves, which, by their communication with the brain, excite in the mind the sense of smell. Seeing. The eye is the organ of sight, and its sensations are of the utmost importance to the well-being and safety of ani- mals. The eye is composed of three coats, covering one another, and enclosing different substances called humours. The three eoats are the sclerotica, the choroides, and the retina. The three humours are the aqueous, the crystalline, and the vitreous. Ob- jects are seen by means of their images being painted on the retina of the eye, in an inverted position, though they appear erect. When the crystalline humour loses its transparency, the disorder is called a cataract, and the remedy applied is called couching, which is performed by thrusting a fine awl through the coats of the eye, and pushing the crystalline to the bottom of the eye, where it will remain, and its deficiency may be sup- plied with a convex lens. When the defect of vision is in the optic nerve, it is called a gutta serena, and the disorder is gene- rally incurable. The external parts of the eye are, the eye- brows, the eye-lids, and eye-lashes. The eye-brows defend stances which might otherwise fall into the eye. The eye-lids act as curtains, by covering and protecting the eyes during light. The eye-lashes guard the organ from danger, and protect it from dust and insects floating or flying in the atmosphere. The mouth contains the teeth, which are inserted into, two moveable bones, the upper and under jaw. The front or cut- ting teeth are in general wedge-shaped, and so placed that in action their sharp edges are brought into contact. Next to long all the Americans, except the Esquimaux. variety, includes the inhabitants of Malacca, of the South Sea, Ladrone, Philippine, Molucca, and Sunda islands. variety is distinguished by the colour of the hair, and some of sound. the eyes from too strong a light, and serve to turn away sub- these are situated the canine teeth or tusks, which are in general longer than the front teeth, comical, and pointed. The teeth in the back of the jaw, and between which the food is chewed or masticated, are called grinders. In such animals as subsist on vegetable food, the latter are somewhat flattened at the top ; but in the carnivorous tribes, their upper surfaces are furnished with sharp and conically pointed protuberances. It is principally from the numbers, form, and disposition of the teeth, that Linnaeus has arranged the various genera or tribes of quadrupeds. - The class Mammalia has been distributed into seven orders, founded for the most part on the number and arrangement of the teeth; and on the form and construction of the feet, or of those parts in the seals, whales, and other animals, which sup- ply the place of feet. - : Orders of Mammalia.-1. Primates, have the upper front teeth generally"four in number, wedge-shaped, and parallel; and two teats situated on the breast, as apes and monkeys. 2. Bruta, have no front teeth in either jaw; and the feet armed with strong hoof-like nails, as the elephant. 3. Ferae, have in gene- ral six front teeth in each jaw ; a single canine tooth on each side in both jaws; and the grinders with conic projections, as the dogs and cats. 4. Glires, have two long projecting front teeth in each jaw, which stand close together; and no canine teeth in either jaw, as the rats and mice. 5. Pecora, have no front teeth in the upper jaw; six or eight in the lower jaw, situated at a considerable distance from the grinders; and the feet with hoofs, as the cattle and sheep. 6. Bellua, have blunt wedge-shaped front teeth in both jaws; and the feet with hoofs, as the horses. 7. Cetae, have spiracles, or breathing holes, on the head ; fins instead of fore feet; and a tail flattened hori- zontally, instead of hind feet. This order consists of the nar- wals, whales, cachalots, and dolphins. MAMMARY GLAND, in Anatomy, is a glandular substance situated in the breast, and secreting the milk. MAN. The varieties of the human species, as arranged by Blumenbach, are five in number:—1. Caucasian variety, which includes the Europeans, (excepting the Laplanders, and the rest of the Finnish race,) the western Asiatics, as far as the river Ob, the Caspian sea, and the Ganges, and the northern Africans. 2. Mongolian variety, which includes the rest of the Asiatics, (excepting the Malays ;) the Finnish races of the colder parts of Europe, as the Laplanders, &c. and the tribes of Esquimaux ; extending over the northern parts of America from Bhering’s Strait to the extremity of Greenland. 3. Ethio- pian variety, contains the remaining Africans, besides these classed in the first variety. 4. American variety. To this be- 5. Malay Each striking peculiarities of feature. We shall now briefly describe the external and internal structure of the human body, and the five senses. - - External Structure of the Human Body.—Among all the visible parts of the body, the head holds the most distinguished place; both because of its beauty, and because it contains the princi- ples of sense and motion. All the sentiments and passions of the soul are painted on the face, which is the most beautiful part of man; and where the principal organs of sense are found, through the medium of which we receive impressions from external objects. The diſferent motions of the lips, and those of the tongue, whether it touch the palate or the teeth, serve for the articulation of words, and the different inflexions By the teeth we can cut or grind our food; and the saliva, so necessary to digestion, is furnished by a great number of glands, which are contained in the mouth. The head is placed upon the neck, and turns as on a pivot, to any sheep; and in our waking hours they diffuse a fluid over the eye which renders it better adapted to transmit the rays of | side we please. After the neck comes the shoulders, so formed that they are able to bear heavy loads. To the shoulders the arms are joined ; and to those, the hands, which are so con- structed as to perform an infinity of motions; to touch, take, raise up, draw back, repel, &c. the joints and bones serving to i support and facilitate these motions. The breast includes and defends the heart and the Hungs; and for this purpose it is | composed of strong and hard ribs and bones. The diaphragm M A N M A N DICTIONARY OF MECHANICAL SCIENCE. 615 'separates the breast and belly, which contains the stomach, liver, spleen, and intestines. All this mass rests upon the hips, thighs, and legs, which, like the arms, have different arti- culations favourable to motion and rest. The feet sustain the whole, and the toes also contribute to it, because they serve to fix the feet more firmly upon the ground. The skin and flesh cover the whole body. The hair and the down, which are found in different parts, protect them from the injurious effects of cold. The bones, the most compact and solid parts of the body, serve for the attachment and support of all other parts. Bones are firm, hard, and perfectly insensible, they are divided into the long, the cylindrical, and the flat. There are 248 sepa- rate bones in the human body; these, connected with wires, are sometimes made up into an artificial skeleton. There are eight separate bones in the skull, that serves as a vault for the brain. The vertebrae of the neck, so called from the ease with which they move, are separated from one another by an elastic substance. They support the head, which by their means is readily moved up and down, and turned round on either side as far as is necessary, like a piece of mechanism in a ball and -socket; to the breast bone, the seven true and five false ribs are fastened : the spine extends from the skull to the end of the loins, and serves to lodge and defend the spinal marrow : the pelvis' supports the abdomen, and the thorax reaches from the neck to the end of the breast bone, serving as a chest or place of safety for the heart, lungs, &c. - The Muscles, Arteries, Weins, and Circulation of the Blood.— The muscles constituting the flesh are susceptible of contrac- tion and relaxation, and, with the help of the tendons, are the instruments of animal motion. The muscles are either volun- tary or involuntary. The motions of the former are subject to the will, as in the case of the arms, legs, &c. The heart, which is a hollow muscle, and the stomach, intestines, &c. act upon their contents by means of muscular fibres, called involuntary muscles, because their motions depend not on the will. Each large muscle consists of two parts, viz. the belly, which is the active part, and its cord-like extremities called tendons, which fasten the muscle to the bones, and perform their action by con- tracting both ends towards the centre. The red colour which distinguishes the muscular parts, of animals is owing to the number of blood-vessels dispersed through their substance. The nerves, long, white, medullary cords, originate in the brain and spinal marrow, and serve for sensation. Sensibility, there- fore, depends on the nerves; motion, on the muscles. The nerves conduce to all the enjoyments and sufferings of life, and to the intellectual faculties of man : the muscles are the chief support of animal life, and the source of all the bodily powers. The heart is the principal organ of life; it contains four cavi- ties for receiving the blood, and giving it a fresh impulse through the arteries. The arteries originate in the Heart, and through them the blood is carried from the heart to every part of the body, for the preservation of life, generation of heat, nutrition, and the secretion of the different fluids. The pulse, felt at the wrist, temples, and various parts of the body, is occasioned by the reciprocal action of the heart and arteries, when the blood is driven from the heart into the arteries to be distributed through the whole body. The arteries terminate in small microscopic veins, which bring back the blood from the extremities to the heart. ties of the arteries: they continually increase in size as they approach the heart: they do not pulsate, but the blood they receive from the arteries, they carry back with a slow motion, and it is prevented from returning by innumerable valves. The double circulation of the blood is this: one motion is from the heart to the lungs, for the purpose of receiving oxygen from the air; the other motion is over all the parts of the body, to give out its nutritive and vital properties to the whole machine. The Brain and Nerves.—The brain, a small pulpy mass of a whitish colour, occupies all that cavity formed by the bones of the skull. The spinal marrow, a continuation of the brain, passes out of an opening in the skull, and runs down the canal of the back-bone, giving out nerves in its passage. The nerves run out in pairs, separate and spread over the whole body. The brain and nerves constitute entire the organs of feeling and sensation, the other parts of the body being incapable of feel- The veins originate at the extremi-. ing. Excitement to action, produced by the will, proceeds from the brain and spinal marrow, through the medium of the nerves. The nerves are therefore the organs, the brain the receptacle, of all our sensations, and the source of all our ideas. - The Stomach, Liver, Digestion, &c.—The stomach, shaped like a bag, is the grand receptacle for the food, where it is retained until it is changed by digestion. The stomach has two open- ings, one called the oesophagus, through which the food passes into it; the other, intended to carry away the digested sub- stance, is called the intestinal canal. The chief agent in diges- tion is the gastric juice; by the muscular nature of the stomach, the food when properly digested is propelled through the intes- tinal canal into the intestine, a membranous tube, about five times the length of the person in which it is contained. Food is called chyme, in which state it enters the intestine, where it undergoes another change, and the chyle, a milk-like substance, is separated from it. Chyle is that substance from which the blood is formed, it is absorbed by the mouths of the lacteal vessels, every where distributed in the intestines, while the fecu- lent parts of the chyme and the bile are driven into the large intestine, by which it is expelled from the body. The liver is formed for the secretion or separation of the bile from the blood, which passes into the dºctus hepaticus, and thence into the gall-bladder, where it is kept till it is wanted to mix in the intestine. The chief uses of the bile are, to extricate the chyle from the chyme; and to excite the peristaltic motion of the bowels. The lacteals convey the chyle from the intestine into the jugular vein, that empties itself into the heart. The kid- neys are two glandular substances which drain the system of its redundant water; for this purpose a considerable portion of the biood is perpetually passing into each kidney, where it leaves its superfluous water, and then returns into the circu- lation by means of a particular vein. The water thus strained from the blood is carried by canals into the bladder, into which it passes through its two coats, which answer the purpose of a valve to prevent regurgitation. MAN. By this word, used in the sea language, a ship is fre- quently understood as a Man of war, a Merchantman, a Guinea- man, an East Indiaman, a Greenlandman, &c. in all which instances the word ship is implied. To Man, is to place men sufficient for any particular exercise at the proper station: as, Man the Capstan, that is, place the men to the bars in readi- ness to heave. IHan the Top-sail Sheets, that is, let the men lay hold of, and be ready to pull up, the top-sail sheets. To Man the Ship, is to range the people on the yards and rigging, in readiness to give three cheers, as a salute. To Man the Yards, to send a sufficient number of men upon the yards to reef or furl the sails. To Man a Prize, to send a proper num- ber of men on board to navigate her. MANCIPLE, (Manceps, ) a clerk of the kitchen, or caterer. An officer in the inner temple was anciently so called, who is now the steward there; of whom Chaucer, the ancient English poet, sometime a student of that house, thus writes: A manciple there was within the temple, Of which all caterers might take ensample. This officer still remains in colleges in the universities. MANDAMUS, in Law, a writ that issues out of the Court of King's Bench, sent to a corporation, commanding them to admit or restore a person to his office. This writ also lies where justices of the peace refuse to admit a person to take the oaths in order to qualify himself for enjoying any post or office; or where a bishop or archdeacon refuses to grant a probate of a will, to admit an executor to prove it, or to swear a churchwarden, &c. - MAN DRAKE, See ATRoPA. MAND REL, a kind of wooden pulley, making a member of the turner's lathe. Of these there are several kinds ; as, Flat Mandrels, which have three or more little pegs or points near the verge, and are used for turning flat boards on. Pin Man- drels, which have a long wooden shank to fit into a round hole made in the work to be turned. Hollow Mandrels, which are hollow of themselves, and used for turning hollow work. Screw Mandrels, for turning screws, &c. MANE, the hair hanging down from a horse's neck, which should be long, thin, and fine; and, if frizzled, so much the better. - 616 M A N M A N DICTIONARY OF MECHANICAL SCIENCE. ... MANEGE, or MANAGE, the exercise of riding the great' horse; or the ground set apart for that purpose; which is sometimes covered, for continuing the exercise in bad weather; and sometimes open, in order to give more liberty and freedom both to the horseman and horse. See HoRSEMANSHIP. The word is borrowed from the French manage, and that from the Italian maneggio; or, as some will have it, a manu agendo, “acting with the hand.” - - MANGANESE, a metal which is not only an object of inte- rest in the speculations of the experimental chemist: but of the utmost use in manufactures, from its being employed to furnish the chlorine gas, which is so effectual in bleaching. It is a metal of a dull whitish colour when broken, but which soon grows dark by oxidation from the action of the air. It is hard, brittle, though not pulverizable, and rough in its fracture; so difficultly fusible, that no heat yet exhibited has caused it to run into masses of any considerable magnitude. Its sp. gr. is 8-0. When broken in pieces, it falls into a powder by sponta- neous oxidation. Concentrated sulphuric acid attacks manga- nese, at the same time that hydrogen gas is disengaged. The ore of manganese, which is known in Derbyshire by the name of black wadd, is remarkable for its spontaneous inflammation with oil. It is of a dark brown colour, of a friable earthy ap- pearance, partly in powder, and partly in lumps. If half a pound of this be dried before a fire, and afterwards suffered to eool for about an hour, and it be then loosely mixed or knead- ed with two ounces of linseed oil; the whole, in something more than half an hour, becomes gradually hot, and at length bursts into flame. This effect wants explanation. It seems, in some measure, to resemble the inflammation of oils by the nitric acid. Manganese was used chiefly by glass makers and pot- ters; but the important discovery of cñiorine has greatly ex- tended its utility. - . MANGER, in sea language, a small space extending athwart the deck of a ship of war immediately within the hawse-holes, and separated on the after-part from the other part of the deck by the manger board, a strong bulk-head, built as high as, and serving to stop the water which sometimes rushes in at the hawse-holes, and would otherwise run aft in great streams on the deck; the water, thus stopped, is again returned into the sea through the scuppers. MANGLE, a valuable domestic machine, employed for the purpose of smoothing such linen as cannot be conveniently ironed. Various patents have been granted for improvements in this machine : but, as many of them are too complicated to be understood without very tedious details, we have repre- sented an improved mangle contrived by Mr. Jee, of Rother- ham. (See the Plate.) A, fig. 11, points out the great wheel, which, in machines of a full size, is 15 inches in diameter. B, the arbor, on which the nut, C, is fixed. D, the handle of the winch. E, the crank, 21 inches in length. F, the rod of the crank. G. G., represents the hollow studs, by which the ends of the bed are lifted up. H H, the levers. IIII, the four pulleys fixed on the moveable bed K. L. L., the ends of the rollers. Fig. 12, represents a front view of one of the hollow studs G, to shew its form when standing at the end of the bed; and into which the levers enter alternately, as often as it becomes necessary to elevate the bed, in order to put in, or take out, the rollers. This mangle is so constructed, that the handle requires to be turned one way only, in consequence of which the machine moves with greater facility, and with incomparably less injury to the linen, than by varying the turnings, and in a manner eutting the different folds. . Besides, it possesses the great advantage, that a woman and one boy are sufficient to work it, and can perform as much labour in the same period of time as three or four persons with mangles of the common con- struction. Morris's Patent MANGLE, being compact and moderately simple, may here be described. This mangle is constituted of four horizontal rollers, the pivots of which play on suitable sup- ports in a stout wooden frame put together with bed-screws. To avoid circumlocution, we shall denote these four rollers by the letters A, B, C, D, (see the Plate.) The two rollers A and B, whose axles bear on brass or iron, let into the wooden frame, are posted side by side, but not so as to touch. C is a moveable roller, about which the linen or cloth to be mangled is rolled, and is then placed upon the rollers A and B, so as to lie in part between them. The axis of the fourth roller D. works in pieces of brass or iron, which slide between two other pieces of metal, so that this roller D admits of elevation and depression, by means of a lever working upon a horizontai shaft (at the top of the frame) and chains of suspension. The pieces of metal in which the axle of the roller D runs have long vertical pieces of iron attached to them, so as to reach below all the rollers; and to hooks at the lower extremities of these irons are hung chains carrying either a rectangular platform loaded with weights, or a rectangular box containing stones or other ponderous matter. In using this machine, the lever is pressed down and fastened by a hook; by this process the roller D, and platform below all, is elevated ; then the linen to be smoothed is wrapped about the roller C, which is next laid to rest between the rollers A and B. The lever is then freed from the hook which kept it down, and the action of the pon- derous matter on the platform brings the roller D into contact with the roller C : in this state a rotatory motion is applied to all the rollers by means of a winch fixed to the axle of D; and in a short time the pressure of the roller C, against A, B, and D, will give the requisite smoothness to the linen. The patentee says, this machine will act best with a wheel on the axis of each of the cylinders A and B, and a pinion between them, with a ſly-wheel on the axle of the pinion, to which mo- tion being given, all inequalities of pressure will be conquered with great ease. This machine is not confined to mangling only, but may be used with success as a copper-plate printing press, a letter-copying machine, &c. Art Improved MANGLE, by Elisha Pechey.—In this machine, a regular alternating motion is carried on by a power con- tinued in one direction. The novelty in this mangle is, the contrivance for obtaining the alternate forward and backward motion of the box, and consequently of the rollers, by con- tinually turning the winch in the same direction. More than one mode of obtaining this object is already before the public, but the simplicity, ingenuity, and efficacy of the arrangement adopted by Mr. Pechey for this purpose, will be apparent from the following description:— Figure 1 exhibits a plan or view of the upper side of the mangle. Fig. 2 is an end view. Fig 3 is a side view ; the bot- tom parts of the frame being represented as broken off, so as to reduce it within the plate; but the whole height is seen in fig. 2. The same letters of reference apply to the same parts in each figure. Fig. 4 is a section of a double rack, a a and b b, together with the plummer blocks or guides c c, (which support and guide the rack or axis, d d,) being cut by a plane in the direction of, and perpendicular to, the axis. Fig. 5 is a similar section, shewing the rack in another situation, as will be hereafter described. Fig. 6 is a view of part of the shaft d d, shewing the two journals e e, which turn and are supported in the plummer blocks, and also the pinion f of three teeth, formed in the middle part of the shaft which works into the racks. Fig. 7 is a section of the plummer block, cut in the direction of the dotted line g g, fig. 4, and of the pinion f, toge- ther with a side view of one end of the racks a a and b b. Figs 4, 5, 6, and 7, are drawn double the size of the former. A A, &c. is the frame of the mangle, B B the moveable box which contains heavy weights, and C C two rollers, which are all made in a similar way to other mangles. On the upper side of the frame AA, &c. are fixed head stocks D D, which are fixed and kept perpendicular to each other by an iron bar h h; on the upper side of the bar are fixed the plummer blocks ce; the upper and lower parts of the plum- mer blocks have projecting pieces i i and jj, which support and guide the double rack, see figs. 4 and 5. a a and b b is the double rack, which is fixed parallel to the box B B, by means of two perpendicular studs k.k; the studs pass loosely through loops in each end of the racks, so that the rack is at liberty to move up and down, being at the same time prevented from sliding off by the pins ll; each end of the rack is supported by two spiral springs m m fixed on the upper side of the box: the ends of these springs pass through small holes in the ends of the rack, and tend to support it in a middle situation, such a position as that the pinion f, fig. 7, shall be in gear with the M A N M. A. N. 617 DICTIONARY OF MECHANICAL SCIENCE. upper bar of the rack. The double rack consists of a flat bar of iron, having teeth formed in the internal part of it, (as shewn in figs. 3 and 7,) and also two fins, or ribs, ºn and 0, fixed to the upper and lower edges of it, and projecting on each side of the rack. The use of these fins is to support the rack in the two situations, as shewn in figs. 4 and 5. d d is a shaft or axis, which is supported by the head stocks D D, and by the plum- mer blocks c c, having a ſly-wheel p fixed to one end of it, and a winch q to the other, by which means the machine is put in motion: in the middle part of the shaft d d is the pinion f, which works in the teeth of the rack; in figs... 3 and 7, the pinion is represented working in the rack a a now, suppose a rotatory motion be given to the winch, the pinion will cause the rack, together with the box, &c. to move in a longitudinal direction till the end of the rack has arrived at the pinion, when it will be seen, by referring to fig. 7, that the rack cannot pass any further in that direction. By continuing to turn the winch in the same direction as at first, it is evident that the next tooth of the pinion will take into the gap in the end of the rack, and thus cause the rack to slide up the stand k, till the fins on each side of the rack are raised above the projecting pieces i i and jj of the plummer blocks; the next succeeding tooth will act in the first gap of the lower rack b b, which will cause the rack, together with the box, &c. to move in the con- trary direction till the other end of the rack has arrived at the pinion, when a tooth of the pinion will act in the gap in that end, and cause the rack to slide down the stud h, when the next tooth of the pinion will act in the first gap of the upper rack, and cause the rack to move in the direction first mea- tioned, and by continuing the motion of the winch in the same direction, an alternate motion of the rack box, &c. is effected. To replace or change the rollers C C, one of the arms r or s must be turned on the joint by which it is fastened to the plummer block in a direction parallel to the side of the rack, as shewn at r in fig. 1. The arm forms an inclined plane, as shewn at r, fig. 3, so that when the end of the box B B approaches towards the centre of the frame, the friction roller t (one of which is fixed to each end of the box) passes up the arm or inclined plain r, and raises the end of the box, so that the roller C may be removed. A new species of mangle, on the principle of the parallel ruler, has been invented, and is called the perpendicu- lar mangle; but it seems greatly inferior to the last mentioned machine of this name. MANICHEES, in Church History, a sect of Christian here- tics in the third century, the followers of Manes, who taught that there were two principles, or gods, co-eternal and inde- pendent on each other; the one the author of all evil, and the other of all good. MANIFEST, an inventory of the whole cargo of a merchant ship. *ANIFEsto, a public declaration made by a prince in writing, shewing his intentions to begin a war or other enter- prise, with the motives that induce him to it, and the reasons on which he founds his rights and pretensions. - MANILLE, in Commerce, a large brass ring in the form of a bracelet, either plain or engraven, flat or round. Manilles are among the commodities which the Europeans carry to the coast of Africa, and exchange with the natives for slaves. These people wear them as ornaments on the small of the leg, and on the thick part of the arm above the elbow. The great men wear manilles of gold and silver; but these are made in the country by the natives themselves. MANIPULUS, in Roman Antiquity, a body of infantry con- sisting of 200 men. s MANIS, in Natural History, a genus of mammalia, of the order bruta. These animals resemble the ant-eater, and feed like that creature by protruding their tongues into the nests of vari- ous species of insects, and retracting them with inconceivable suddenness, with their prey attached to the tip. There are three species; the chief of which, the long-tailed manis, has a tail more than twice the length of its body, and is often in the whole seen five feet long. Its colour is a dark brown, with a tinge of yellow, and it displays a yery brilliant gloss. It is perfectly covered, except on the belly, with large scales resembling the substance of horn. It is a native of India. The short-tailed . manis, much thicker and shorter than the former, is covered with scales still thicker and stronger. It is found in many parts of India and Africa. It moves with great slowness, but on imminent danger of attack, rolls itself up with the compact- ness of a ball, and defies, in this state, the attempts even of some of the larger beasts of prey. It frequents marshy and woody places, and lives almost entirely on insects, particularly on ants. MANNA. Several vegetables afford manna, but the ash, the larch, and the albagi, afford it in the largest quantities. The ash which affords manna grows naturally in all temperate cli- mates; but Calabria and Sicily are the most natural countries to this tree. The manna flows naturally from this tree, and attach- es itself to its sides in the form of white transparent drops, but the extraction of this juice is facilitated by incisions made in the tree during summer. Its smell is strong, and its taste sweet- ish and slightly nauseous; if exposed on hot coals, it swells up, takes fire, and leaves a light bulky coal. Water totally dis- solves it, whether hot or cold. If it be boiled with lime, clari- fied with white of egg, and concentrated by evaporation, it af- fords crystals of sugar. Manna affords by distillation, water, acid, oil, and ammonia; its coal affords fixed alkali. This sub- stance forms the basis of many purgative medicines. MANNER, in Painting, a habitude that a man acquires in the three principal parts of painting, the management of colours, lights, and shadows; which is either good or bad according as the painter has practised more or less after the truth, with judgment and study. But the best painter is he who has no manner at all. The good or bad choice he makes is called goute. MANNERS, the plural noun, has various significations; as, the general way of life, the morals, or the habits, of any person or people; also ceremonious behaviour, or studied civility. See the next article. Good MANNERs, according to Swift, is the art of making those people easy with whom we converse. Whoever makes the fewest persons uneasy, is the best bred man in the com- pany. As the best law is founded upon reason, so are the best manners. And as some lawyers have introduced unrea- sonable things into common law ; so, likewise, many teachers have introduced absurd things into common good manners. MANOEUVRE, in a military sense, consists solely in dis- tributing equal motion to every part of a body of troops, to enable the whole to form, or change their position, in the most expeditious and best method, to answer the purposes required of a battalion, brigade, or line of cavalry, artillery, or infantry. It has always been lamented, that men have been brought on service without being informed of the uses of the diſſerent ma— noeuvres they have been practising; and, having no ideas of any thing but the uniformity of the parade, instantly fall into dis- order and confusion when they lose the step, or see a deviation from the straight lines they have been accustomed to at exer- cise. It is a pity to see so much attention given to show, and so little to instruct the troops in what may be of use to them in real service. No manoeuvre should be executed in presence of the enemy, unless protected by some division of the troops. MANOMETER, an instrument, intended to measure the rarefaction and condensation of elastic fluids in confined cir- cumstances, whether occasioned by variation of temperature or by actual destruction, or generation of portions of elastic fluid. It is sometimes called manoseope. Mr. Boyle's statical baro- meter was an instrument of this kind; it consisted of a bubble of thin glass, hermetically sealed, about the size of an orange, which being counterpoised when the air was in a mean state of density, by means of a nice pair of scales, sunk when the atmosphere became lighter, and rose as it grew heavier. This instrument would evidently indicate the changes of density in the atmosphere, but it leaves us uncertain as to the cause, whether it is from the change of its own weight, or of its tem- perature, or of both. The manometer constructed by Mr. Ramsden, and used by Captain Phipps, in his voyage to the North Pole, was composed of a tube of a small bore, with a ball at the end ; the barometer being at 29.7, a small quantity of quicksilver was put into the tube, to take off the communi- cation between the external air, and that confined in the ball, and the part of the tube below this quicksilver. A scale is placed on the side of the tube, which marks the degrees of dila- 7 S 618 Mł A. P. M A P I).IUTIONARY OF ME CHANICAL SCIENCE. tation arising from the increase of heat in this state of the weight of the air, and has the same graduation as that of Fah- renheit's thermometer, the point of freezing being marked 32. In this state, therefore, it will shew the degrees of heat in the same manner as a thermometer. But if the air becomes lighter, the bubble enclosed in the ball, being less compressed, will dilate itself, and take up a space as much larger as the com- pressing force is less; therefore the changes arising from the increase of heat will be proportionably larger, and the instru- ment will shew the differences in the density of the air arising from the changes in its weight and heat. Mr. Ramsden found, that a heat equal to that of boiling water, increased the magni- tude of the air from what it was at the freezing point # of the whole. Hence it follows, that the ball and part of the tube below the beginning of the scale, is of a magnitude equal to almost 414 degrees of the scale. If the height of both the manometer and thermometer be given, the height of the baro- meter may be determined also. MANOR, was a district of ground held by lords, or great personages, who kept in their own hand, so much land as was necessary for the use of their families. The other lands they distributed among their tenants. The residue of the manor, being uncultivated, was termed the lord's waste, and served for common of pasture to the lord and his tenants. All manors existing at this day must have existed as early as King Ed- ward I., and must have a court baron. . MANSE, MANsus, MANs A, or MANsu M, in ancient law- books, denotes a house, or habitation, either with or without land. See House and MANsion. The word is formed from & º, “abiding;” as being the place of dwelling or resi- ©In CC, # MANSLAUGHTER. See HoMICIDE. MANTLE, or MANTLE-TRee, in Architecture, the lower part of the chimney, or that piece of timber which is laid across the jambs, and sustains the compartments of the chimney-piece. MANtle, or Mantling, in Heraldry, that appearance of fold- ing of cloth, flourishing, or drapery, which in any achievement is drawn about a coat of arms. See HERALDRY. - MANTELETS, in the art of war, a kind of moveable para- pets, made of planks about three inches thick, nailed one over another, to the height of almost six feet, generally cased with tin, and set upon small wheels, so that in a siege they may be driven before the pioneers to shelter them from the enemy’s small shot. MANTIS, a genus of insects, of the order hemiptera. There are upwards of 60 species; the chief is the M. oratorea, or camel cricket, found in the southern parts of Europe, of a beautiful green colour, nearly three inches in length, of a slender shape, and in its general sitting posture, is observed to hold up the two fore legs as if in the act of devotion. The insect is of a predacious disposition, living on smallerinsects, which it watch- es for with great anxiety: it is also very pugnatious, and when kept with others of its own species in a state of captivity, they will attack each other with the utmost violence till one is de- stroyed. The conqueror devours his antagonist. . MANUFACTURES may be defined, the arts by which natu- ral productions are brought into the state or form in which they are consumed or used. The principal manufactures are those of which the various articles of clothing are fabricated ; as the woollen manufacture, the leather manufacture in part, the cotton manufacture, the linen manufacture, and the silk manufacture ; others supply articles of household furniture, as the manufac- tures of glass, porcelain, earthenware, and of most of the me- tals in part; the iron manufacture furnishes implements of agriculture, and weapons of war; and the paper manufacture supplies a material for communicating ideas and perpetuating knowledge. - MANURE, See HUSBANDRY. MAPLE. Acer Pseudo Platanus. By tapping this tree it yields a liquor not unlike that of the birch tree, from which the Americans make a sugar, and the Highlanders sometimes an agreeable and wholesome wine. MAPS. A map represents the earth, or only a portion of its The former are called universal : The upper part of a map is the surface, as Great Britain. the latter, particular maps. north, the lower the south, the east is on the right hand side distance of any place from the equator, north or south. and the west is towards the left hand, if the map be laid before you as it can be read. The latitudes are marked on the perpendicular margins of the east and west; the longitudes on the horizontal margins at top and bottom. . The Construction of MAPs.-Prob. I. To construet a Map of the World, on the plane of a meridian 419 by the globular projection of the sphere. (See the Plate, fig. 1.)—The globular projection of the sphere, represents spaces on the surface of the globe by equal spaces of the projected map, as nearly as a spherical surface can be represented on a plane. The plane of a meri- dian is the plane of one of the great circles of the sphere pass- ing through both poles, and crossing the equator at right angles. A hemispherical map, is a representation of the entire surface of the Earth, projected on the plane of one of its great. circles. - 1. To draw the meridians, or circles of longitude. —Draw A B and N S at right angles to each other. A B represents the equator, and N S the aris meridian. From C as a centre, with any radius, C A or C B, according to the size of your paper, describe the circle A N B S. This circle is then the plane of your projection. Divide the four radii, CA, C N, C B, C S, each into nine equal parts. . . Now, to draw the meridian 80° west of Greenwich, we have the two poles, and the point 80° in the equator, A. B. From N as a centre, and with N C as radius, describe the arc Z C Z; also from S, with the same radius, describe the arc X C X. Remove the compasses to the point 80 on the equator, and describe the arcs 1, 1, and 2, 2. Through the intersections at 1 and 2, draw lines from 2, 2, through the points 1, 1, till they intersect the diameter B.A. produced in D. Then will D be the centre from which, with the radius D 80°, or D N, or DS, the meridian of 80° west longitude from Greenwich must be de- scribed. The same radius will draw the meridian expressing 140° W. L.; and, in the other hemisphere, the corresponding meridians of east longitude. The meridian of 50° is drawn in the same manner as that of 80°, except that the point 50 on the equator (A B) is the centre from which, with the radius C B, the intersections are made at a, a, and b, b, on the arcs described from N and S. The point E, where the lines b a, b a, meet on the equator, is the centre for the meridian of 50° W. longitude. The same radius serves for the other three meridians 30° within the circle of projection. In this manner are all the other meridians for both hemispheres to be drawn; as may be seen in the Plate. fig. 7. * 2. To draw the parallels of latitude. (Fig. 2.)—Latitude is the The same construction remaining, and the radii C N, CS, divided each into nine equal parts. Divide the circumference A N B S into thirty-six equal parts, each quadrant A N, B N ; AS, BS, will be divided into nine equal parts, which, being again sub- divided into ten equal parts each, will give us 360 equal parts or degrees. - To draw, now, the parallel of 30° north latitude, set one foot of the compasses in the point 30 on the aaris meridian NS, and with any radius describe the circle KTL. Set, again, one foot of the compasses in the points 30, 30, in the circumference, and intersect the circle KTL in the points s, s, n, n. Through n n and ss draw the straight lines n m, ss, meeting each other in the point R of the axis S N, produced to R; and with R as a centre, and R. 30 as a radius, describe now the parallel of 30° north latitude. The same radius is used for 30° south latitude. After the same process the parallel of 60° north latitude is drawn, as may be easily conceived by inspecting the figure. And in this way proceed with all the other parallels in both hemispheres; as is evident from fig. 7. - •. This is the construction. The minutiae of filling up the map, requires the attention of the delineator, in strictly observing the situations of objects or lines, as they respectively bear on the practice of map-making. Prob. II. To project a map of the world on the plane of a meri- dian, according and by the ste, eographic projection of the sphere. Fig. 3. 1. To draw the circles of latitude.—Describe, from any centre C, the circle E N Q S, which will represent one-half of the earth's surface. Draw the diameters E Q and N S, inter- secting each other at right angles. E Q is the equator, and N S the axis meridian. Divide the circumference into 360 Aº R - º - º - wº * sºphie *\,, on ºne or a M-ridian ºw cº- ------- º e - 1. c º ºſº º żº º " - - - - ºne, I *Tº “º. " aſ cº zº - \ º º º 1. - º º º º N º - º §§ - to Horizontal wº tº ſº, º N */ º, - Globular Projections - º - on the ºneº Meridian. Published by Fisher sºn & Cº ºn nº lºº. --- M A P M A P DICTIONARY OF MECHANICAL SCIENCE. 619 equal parts; numbered 10, 20, 30, &c, as on the figure. From E to 140 draw the line E 140; bisect the portion a 140 in v, and from v draw the perpendicular va, which produce till it meet NS produced in w. The point a is the centre from which to describe the parallel 2 a 140; or, the 50th degree of south lati- tude. The same radius will serve for the 50th parallel of north latitude ; and after the same manner all the other parallels in both hemispheres are drawn, as they are fully shewn in fig. 8. 2. To draw the circles of longitude.—The uneqºtal divisions of the equator, as indicated by the numbers 10, 20, 30, &c. on the radius C Q, and which are obvious from No. 1, ſig. 11. The points 20, 40, 60, 80, are centres on which the circles of longi- tude S y N are to be drawn; for the remaining circles, produce the diameter EQ, and from N, through every tenth degree in the quadrant N Q, draw lines cutting that diameter produced, and the points of intersection will give the centres for the re- maining circles of longitude : observe, however, that each cen- tre is twenty degrees distant from the preceding one. For the circles of longitude in the other semi-hemisphere, the centres may be formed by setting off the proper distances on the dia- meter E Q, produced the contrary way. Prob. III. To draw a map of the earth on the plane of a meridian, according to Dr. Jamieson's globular projection of the sphere. Fig. 4.—1. To draw the circles of latitude.—Describe the circles EN Q S ; draw the diameters EQ and N S at right angles; the former represents the equator, and the latter the axis meridian. Divide the quadrant Q S into nine equal parts, 10, 20, 30, &c. From each of these divisions draw lines, as Ef 20, Eg 30, Ed 60, &c. Divide into two equal parts the portions fºo, g 30, d 60, &c. and from c, the point of division, let fall the perpen- diculars c F, c G, and c D, produced till they cut the polar dia- meter extended indefinitely. The points F, D, G, are centres, from which the circles of latitude zf 20, 2 G 30, 2d 60, are to be described, and which will be the true representation of the parallels 20, 30, and 60 degrees of south latitude. In the same manner, draw the parallels for every tenth or fifth degree in that semi-hemisphere. To obtain those in the northern hemisphere, set off on the line S N produced, in the opposite direction, the distances which served as centres of the southern parallels: and the northern ones may be described for every tenth degree of latitude. - * 2. To draw the circles of longitude. Fig. 4.—Divide the quad- rant E N into equal parts, 10, 20, 30, &c. Divide also the quadrant SQ into two equal parts at s, of 45° each, and let fall the perpendicular s s from the point s. Set off, on the line N'S produced, S R equal to ss (see fig. 10), then, lines drawn from R. to 10, 20, 30, &c. in the quadrant W S, will divide the radius in the points 10, 20, 30, &c, through which the circles of longi- tude are drāwn (in fig. 4.) in the following manner:-- To find the centre of the circle S 30 N, join the points S 30, and N 30; divide the two lines into two equal parts in o, and let fall the perpendiculars o 30; and the point r, where they meet, is the centre of a circle of 30 degrees of longitude. The other centres may be found exactly in the same manner. Or the centres may be found, mechanically, from the following TRIGo NoMet RicAL TABLE of RAD II:— 10° o 12 e Let the radius of 209 - 25 ºº:: º: º . Q cº - - WarCIS 9 the circle be divided ; 5. º 3 ( added to the distance into 100 equal parts 300 §§ X between C and the by a scale; then the 60° º 133 several points 10, 20, meridian or circle of 700 = 20. 30, &c. in the radius 809 ;: 464 E C. Thus the radius of the circle of 10° of longitude is equal to the distance between 10 in the line E C, and 10 in the line Q Cº the radius of that of 50° = the distance between 50 and 50: that of 80° between 80 in the line EC and a given point in E Q, produced; which, taken from C, will be = 342 parts, of which radius is E 100. - Prob. IV. To project a map of the earth stereographically, accord- ing to the horizontal projection of the sphere, and answering to the latitude of London, (see Dr. Mead's treatise on Maps.) See fig. 5. To draw the meridians.—With any radius, S C or's D, describe the circle CPD, which divide as usual into 360°, and draw CD, PS, at right angles to each other; then will P S be the first meridian, or the north and south azimuth. Azimuth, or vertical circles, are great circles of the sphere, intersecting each other in the zenith and nadir, and cutting the horizon at right angles. On the quadrant DP set off DE = 513° = the latitude of London, and draw parallel to CD, W E, the east and west azimuth of the place. Bisect W E in the point Z, which will be London, or the place of projection. The letters E, S, W, N, represent the four cardinal points, bearing due east and west, north and south, from London (Z), as the centre of the projection. And P, the pole of the meridional projection, is also the pole of the horizontal projection. . Describe now the meridians of the meridional projection C P D, observing to allow them to pass through the pole P, beyond the primitive circle, and to touch the horizontal projection, in the segment W N E. - To describe the parallels of latitude.—Lay a ruler upon W, and move it to every degree, or every tenth degree of the meridian PD continued, marking where it cuts the meridian NS, for through these points the parallels on this side of the pole must all pass. But, as they have not a common centre, the points through which they pass on the other side of the pole are found by moving the ruler along every tenth degree of the meridian PC continued; for wherever the ruler intersects the meridian, N S will be the opposite points through which the parallels are to pass. Having now obtained the diameters of the parallels, we have only to bisect each of them, and with one half, as a radius, describe the correspondent parallel. In fine, the pro- jection may now be completed, as shewn in fig, No. 2. Prob. V. By the globular projection of the sphere, to construct a map with azimuth lines, to shew the bearing and distance of all places within the map, from London, or any other given place in the centre. (See fig. 6.)—It will be perceived that, in this pro- jection, the longitude and latitude of places are neglected, because the map is restricted to the bearing and distance only of places from a station in the centre. Describe a circle of any radius, cross it with two diameters; N S represents the meri- dian of the place assumed as the centre, or the north and south line; and W E, the east and west line, may be considered the parallel of latitude passing over the place. The intersection of the diameters, as at Z, indicates the place in the centre. Divide each quadrant into 90°, of the exterior circle; and the inner circle into 32 equal parts, to indicate the points of the mariner’s compass. - *; e. The lines radiating from Z are the bearing lines. The three concentric circles, described from the common centre Z.Amay be assumed as one degree each ; and the scale will then con- tain 180 geographical, or 208% English, miles. Suppose we place London in the centre ; then, by the help of the Table of Latitude and Longitude, page 593, we may transfer, into this projection, all places within 180 miles of London. The numbers 1, 2, 3 degrees, on the scale from the centre, are arbitrary, and may be reckoned 10, 20, 30 degrees ; in which case our projection will embrace 1800 geographical, or 2085 Inglish, miles. Or, if the radius, or scale, be divided into 4, 5, 6, or any given number of equal parts, each of those parts may represent 4, 5, 6, or 40, 50, 60, degrees. The scale in this projection must be considered a moveable slip of Bristol board, graduated according to the radius of the projection, and riveted on the map by means of a neat button. Its use is obvious ; for, by moving it round, we determine the bearing and distance, at once, of all places from London, or any other place (Z), in the centre. Fig. 7, represents the globular projection of the sphere; in which the rectangular figure. A B C D represents the skeleton of the map of Asia. The parallelogram E FG H, the skeleton of the map of Africa. The rectangular figure I KL M, the skeleton of the map of North America. The parallelogram N OPQ, the skeleton of the map of South America. Pro- jected on a large scale, these skeletons afford ample exercises for the display of genius and taste in the subsequent filling wip, shading, lettering, and colouring. Prob. VI. To construct a map of the world, on the plane of a meridian, according to the orthographic projection of the sphere. (Fig. 10.) To describe the meridians, which are ellipses.—If they be described through every tenth degree on the equator, the 620 M A P M A P DICTIONARY OF MECHANICAL SCIENCE. distance of each successive meridian, from the centre of the map, is found by means of the parallels drawn through the corresponding divisions of the circumference. If these ellip- tical meridians are drawn with a pair of elliptical compasses, through every fifteenth degree of the equator from the centre of the map, they will appear as in fig. 9. - To draw the parallels of latitude, which are straight lines.—If at 10° from each other, lines be drawn parallel to the equator, they will indicate the parallels of latitude. But, if they be drawn through every fifteenth degree of latitude, they will appear as in fig. 9. * Note.—This projection is chiefly useful for astronomical pur- poses, to represent a sign of the Zodiac. It is obvious, that twelve such projections would furnish the means of depicting the twelve signs. . Prob. VII. To project, on the plane of the equator, a map of the world, according to the globular projection of the sphere. (Fig. 10.)—In fig. 10, the point R is distant from N equal to the line ss, or the sine of 45° in fig. 4. This point R is the place of the eye whence the spectator, supposing the sphere pellucid, views the entire hemisphere W S E. The lines which pass from 10, 20, 30, &c. in W S to the eye at R, cross the line W P ob- liquely in the points 10, 20, 30, &c. Thus, the equal division, or nearly so, of the radius is obtained; and this is the principle of the globular projection of the sphere. 1. To draw the meridians ; which, in this map, are straight lines, radiating from P, the pole.—Divide the circumference into 36 or 360 equal parts, and to each of these equal divisions draw straight lines, as seen in No. 2; and the meridians for one hemisphere, projected on the plane of the equator, are now laid down. - - * 2. To draw the parallels of latitude; which, in this map, are concentric circles, described, with their respective radii, from P the common centre.—From the observation with which we have pre- faced this construction, we know that W P, the radius (No. 1), is divided into nine equal parts. Then, with the respective radii, P 10, P 20, P 30, &c. of No. 1, describe the concentric circles, as shewn in No. 2, and one hemisphere is completed, so far as respects the projection of the meridians and parallels. Countries, sea-coasts, towns or places, mountains, rivers, &c. are now to be laid down from tables of Latitude and Longitude. Prob. VIII. To construct a map of the world, on the plane of the equator; according to the stereographic projection of the sphere. (See fig. 11.)—As, in this projection, the eye of the observer is placed on the surface of the sphere, and in either pole, as at N (No. 1), the straight lines drawn from the equal divisions of the quadrant W S to the point N, cut the radius W P into un- equal divisions, we derive, at once, the principle of the stereo- graphic projection of the sphere, in which equal spaces on the surface of the earth are represented by unequal spaces on the projection; the space W 10 being double of P 80; and, con- sequently, if P 80 be 1, W 10 will be 2; and any quadrilateral continued between W 10 and 10° of latitude, on a projection on the plane of the meridian, will be four times the size of a quad- rilateral comprehended by P 80 and 10° of latitude, because the square of 2 is 4, and the square of 1 is 1. I. To project the meridians ; which, in this, as in the last Problem, are straight lines.—The directions given in that Problem apply perfectly to this ; and the process is the same in both. II. To draw the parallels of latitude, which, as in the former pro- iection, are concentric circles.—Take P as the common centre, and with the radii P 10, P 20, P 30, &c. of No. 1, respectively, describe the concentric circles, which shall represent the paral- lels, as shewn in No. 2. - The note subjoined to the last Problem, is to be observed in the execution of this projection. - Prob. IX. To project a map, on the plane of the equator, accord- ing to the orthographic projection of the sphere. (See fig. 12.)—As the eye of the observer is supposed, in this projection, to be situated at an infinite distance from the surface of the sphere, all the lines which are drawn on it are straight lines. On this principle, the meridians would appear, to an eye so situated, as in No. 1, fig. 12; and the parallels would also be straight lines, as represented in fig.9. But, on the plane of a meridian, a map constructed according to this projection has its meridians drawn elliptical, while its parallels are straight lines. (See fig.9) Whereas, on the plane of the equator, the same laws are ob- served as in the two last projections, and the meridians are radiating straight lines; while the parallels are concentric cir- cles, described from the common pole. - 1. To draw the meridians.—Proceed as in the two last prob- lems for their meridians. - 2. To draw the parallels of latitude.—Through the points 80, 70, 60, 50, 40, 30, 20, and 10, of the semicircle NWS, (fig. 12, No. 1,) draw straight lines parallel to N P S ; and the divi- sions 80, 70, &c. on PW, are the divisions which indicate the law of the projection, and the radii for the concentric parallels, which are respectively drawn on No. 2. Scholium. On reviewing these projections, the globular (fig. 10) has decidedly the advantage of presenting equal spaces of latitude throughout its successive geographic quadrilaterals; the stereographic (fig. 11,) presents unequal spaces, diminishing towards the pole, but allowing us more space than the globular for those countries situated near the equator; and, in this re- spect, answering better than the other the conditions of the projection. The orthographic is the reverse of this last, as it allows to the polar regions more space than either of the other two ; but then the countries contiguous to the equator are abandoned to a greater error in respect of latitude than even the polar regions in the stereographic projection. For geogra- phical purposes, the globular is preferable; for astronomical uses, the stereographic merits attention, when the signs of the Zodiac, or stars within the tropics, are to be laid down, as seen from either pole; and the orthographic suits best the de- lineation of the arctic or antarctic constellations. - Prob. X. To project a map of Asia, according to the globular projection. (See fig. 13.)—Having drawn any indefinite line A X, and assumed a distance A k for 10° of latitude, set off this distance nine times from A toward X. The point 9, or 90, will be the pole. With the distance Ak set off AB = A D, be- cause the degrees of longitude on the equator correspond with those of latitude on a meridian of the sphere. At the point a, or 70° of latitude, set off a b, and a d, each equal to 20:52; the number of geographical miles corresponding to 70°. Through the points B b, D d, draw the oblique lines B b, D d, which, constructed by the laws of decreasing longitude, terminate in the point X. This point (X) is, therefore, the common centre for ail the parallels of latitude; and it is 30 degrees beyond the pole P, or at the same distance north of the parallel of 60 de- grees, that the equator is south of it. On the equator, EA Q, set off the portion A B, or A D, as often as may be necessary to answer the conditions of the projection; and from each of these points, 50, 60, 70, &c. draw lines to the point X, and they will indicate the meridians, which are all straight lines. Set, now, one foot of the compasses in the point X, and with the other describe the successive concentrics, 10, 20, 30, &c. for the parallels of latitude. Through the point A draw M. L., at right angles to A X ; raise the two perpendiculars M O, L. W., and draw O W, completing the parallelogram O M L W. The de- grees of Iongitude, as on the equator EA Q, or of latitude, as on the meridian 140°, may now be inserted; or upon the parallel lines OM, WL, and O W, M. L. The outline of the Asiatic continent, as in the figure on the Plate, will materially assist the student; but his great reliance must be in a Table of Latitude and Longitude. The eye is . never to be depended on where the process of operation pro- ceeds on such data as an accurate Table affords. . . Prob. XI. To project a map of a particular portion of the earth's surface, as of Italy, containing 6° of latitude, (viz. from the 39th to the 45th degree,) and 9° of longitude, (viz. from the 7th to the 16th of east longitude.)–(Fig. 14.)—Draw the line EF, and in the middle of this line raise the perpendicular D C, which divide into six equal parts, or degrees of latitude, and through C draw the line IK parallel to E. F. The projection is to be regulated, as to size, by the size of the paper, Divide a degree into 10 equal parts, or, if large enough, into 60; and find the number of miles which a degree of longitude contains in the latitude of 39°, viz.—46'62, and, from any scale of equal parts, set off one half of the same, viz. –23:31, on each side of D. Find the number of miles contained in a degree of longi- tude, in the latitude of 45°, viz. –42:43; and from the same scale of equal parts, from which the former measure was taken, (22. an or 4. ºozz//c/a/2. / y ~%z/ Zºe &// Globular Projection • PL , 2. of a Map of the World. * on &e plane of the Azuator. tion of a Map of the World. of the Azuator: pa ax §E ſº QXY #ſº Cź ..., * 4. & N Orthographic Projection of a Map of the World, _2?-T orv &e 2/zzzze, or 6%.e., A'zzazow: cº- s? & 2. Z.2 «2 EFS, Sº, ” ºs Žºržº fº º His # N cºSºj S ºft XX//Hºxx2% X. & # A-2 // * / / / ,’,’ , , ,' * ," / / / / * * * *, *, *, *.x \ * *, *, *, * IPROJECTION OF A NiIAP (9.5" ITALY, Fºz Z4. 4.5 R. E.. I c K & T - 2^-r - l- * * W v2 ', | ." – * ! : *# = FIS \ º, ſº jºſ ), § | | ſ 42 * | º $ ) * º ºl. a H º *Jºu, I ‘. 4Z}— * fe ~~ === | | | º 7 % JS)• | 0 º 9 º A/ Z2 A3 4. 7. 1.5 L S (; iſ, OTBT II, AIR 1PIR () JIE ["I'll (9 N ()|' A TMAP (). F \SIſ A . M. A. P M A. R. 621 DICTIONARY OF MECHANICAL SCIENCE. set off 21.215 on each side of C. Draw straight lines from I to E, and from R to F ; divide them into the same number of parts as the line C D contains, and through the points draw parallel lines. Thus, IKF E is a projection for one degree of longitude, including six degrees of latitude. - Since the degrees must be so drawn, that the two diagonal lines in each must be equal to each other, they are to be pro- jected in the föllowing manner:—1. Take the distance from E to K, or from F to I, and, setting one foot of the compasses first in E, and then in F, describe the arcs L and M. Then set one foot, first in I, and afterwards in K; and, with the same extent, draw the arcs N and O. 2. Take the distance between E and F, and set it off on the arcs described from E to N, and from F to O ; then take the distance between I and K, and set it off from I to L, and from K to M. 3. Draw the lines between ‘L and N, and M and O ; divide them into degrees, and draw || parallels from those points to the corresponding ones in the meridians IB and KF. The same method must be pursued in drawing all the other meridians and parallels which the con- ditions of the map require. Should the map be very large, so much so that the com- passes will not extend to the furthest degree, or from F to I, then draw one or more diagonals at once, and afterwards pro- ceed with the rest. Thus, when the parallelogram PG EN and and H Q OF are described, LIG P and KM Q H may be done. Number the degrees of latitude up both sides of the map, and the degrees of longitude on the top and bottom. Then make the proper divisions and subdivisions of the country; and, from a Table of Latitudes and Longitudes, it will be easy to set down in the map the principal places which should be found in it; for any town must be placed in the intersection of the lines which would indicate its latitude and longitude. Thus Florence must be placed at A, where the circles of 439 46' 30" N. lat. and of 11° 3' 30" E. long. cut each other. And Naples must be placed at B, on the sea-shore, at 40° 45' 15" N. lat. and 14° 17' 30" E. long. In like manner, the mouth of a river, as the Tiber, for instance, must be set down ; but, to describe its whole course, every turning must be laid down according to its latitude and longitude, and the towns and bridges also by which it passes. - Obs. In the projection we have now described, the diagonals being all equal, the number of meridians creates no defect in the representation, because equal spaces on the globe are represented by equal spaces on the map; consequently, places lying in the most remote degrees of longitude are as truly repre- sented as those towards the middle of projection, and their dis- tances will agree with a common measure; so that a pair of compasses, extended between any two places, and applied to the scale, will give the distance without further trouble. When the extent of country is not great, of which a map is to be made, as of a province or country, for example, the meridians, as to semes, are parallel to each other, and may be represented by straight lines. The whole, indeed, will differ so very little from a plane, that it will be sufficient to measure the distances of places in miles, and to lay them down in a plane right-lined map, of which the successive spaces, formed by the meridians and parallels, would be right-angled parallelograms, or, more properly, squares. - Prob. XII. To project a map of Europe.—Having drawn a line for the central meridian of the map, numbered in the Plate 20, 20, assume any convenient distance for 5°, and set it off on this meridian seven times from 35° to 70°; or, to obtain at once the common centre for all the parallels of latitude, set it off 11 times from 35, because 90— 35 = 55, and 55 -- 5 = 11 equal the number of spaces of 5° between 35 and 90. The eleventh, or extreme division, is the pole; and 63 degrees more, beyond it, will be the common centre from which the successive and con- centric parallels of latitude are to be drawn. To draw the meridians, take from a Table of decreasing Latitude, the number of miles in 35° latitude, and set this off as often as is necessary on each side of the eentral meridian (20%), on the parallel, or circle, of latitude 35°. From these points of division draw right lines to the common centre, and they will represent the meridians. But, because the meridians in this map are portions of circles, they are curved after the tolºs manner:-Take the number of miles in 40°, and set this off on the parallel of 400; take from the Table the number of miles in 450, and set this off on the parallel of 45°; take for 500, 609, 650, 700, in like manner; and, having set off these mea- sures on the concentric parallels as often as necessary, the points, when joined to indicate the meridians, will form as many segments of circles as there are meridians: and hence the construction is obvious. For the purpose of drawing maps geometrically correct, it is necessary that schools, or preceptors, or students for them- selves, provide a bow-rule and also beam-compasses. The former is purchased at any mathematical instrument maker's for half- a-guinea; and the latter seldom exceeds twenty-five or thirty shillings. In drawing large maps, it will be found most conve- nient to fasten down the edges of the paper on an even board, which is covered with a smooth oil-cloth. Prob. XIII. To construct a map, which shall contain the degrees of longitude and latitude of Great Britain.-This island lies be- tween 500 and 600 N. latitude, and between 29 E. and 6° W. longitude. Having, therefore, chosen any unit of measure for a degree of latitude, the degrees of longitude must be propor- tioned to it. The length of a degree of longitude in latitude 50 is to one of latitude as 38'57 is to 60; that is to say, a degree of longitude is something more than half the length of a degree of latitude. The exact proportion may, however, be had by a diagonal line, which is divided thus:—Draw an indefinite line, of perhaps three inches; at each extremity raise two perpen- diculars, which make equal to the assumed degree of latitude : complete the parallelogram by drawing its fourth side parallel to the first or base line : reduce the figure to two right-angled triangles by a diagonal. Divide this diagonal into 60 equal parts, and through the points of division draw lines parallel to the sides of the parallelogram, which are of equal length with the degree of latitude. The length of a degree of longitude in latitude 60°, is 3000. Of course, on the diagonal scale, we take off this quantity where the number 30 is found. Then, on each side of the perpendicular, on which we set off the degrees of latitude, this measure 30 is set off three times to the east, and seven times to the west, to answer the conditions of the map. For the corresponding measures at 50% of latitude, take off at 38°57 on the diagonal scale, the proper quantity, and set it off thrice to the east, and seven times to the west, of the perpen- dicular, or first meridian. Through the corresponding points, at 500 and 60% of latitude, draw now the meridians; and, through the equal divisions on the first meridian, draw the parallels of latitude. Then, from 30 east and from 70 west longitude, raise perpendiculars, which will complete the parallelogram that must contain the map. Having next divided into minutes and seconds the degrees of longitude and latitude, towns, cities, or rivers, or mountains, may be accurately laid down; since, by intersectional lines through the correspondent points of lati- tude and longitude, whatever is to be represented on the map may be readily depicted. A mariner’s compass, on any such map, will shew the bearing of one place from another. Prob. XIV. To construct Mercator's Chart of the World.— Draw any indefinite line for an equator, marked o EQUAtoR o in the Plate. Assume any point on this line for the position of the first meridian ; that is to say, the Meridian of Greenwich. Take any assumed distance in the compasses for 10° of longi- tude, or the unit of measure ; set this off on the equator from zero (0), or the meridian of Greenwich, eighteen times on both sides of zero. Then will 360° of longitude be set off; because 18 + 18 - 36, which, multiplied by 10°, gives 360°. Through those 36 equal divisions on the equator draw straight and parallel lines at right angles to the equator: these straight and parallel lines will be the meridians 0, 10, 20, 30, &c. and which, on the projection, are continued across the chart at every 20th degree of longitude, east and west of zero, or Greenwich. MARANTA, Indian Arrow Root, a genus of the monandria monogynia class and order. Natural order scitamineae. There are five species, of which the Indian arrow root has a thick, fleshy, creeping root, full of knots, from which arise many smooth leaves, six or seven inches long, and three broad towards their base; the stalks about two feet high, the ends of which are terminated by a loose bunch of small white flowers, stand- ing upon peduncles two inches long : the flowers are cut into six narrow segments, indented on their edges; these sit upon the 7 T - 622 M A R. M A R DICTIONARY OF MECHANICAL SCIENCE. embryo, which afterwards turns to a roundish three-cornered capsule, enclosing one hard rough seed. It is called Indian arrow-root, because it was thought to extract the poison from wounds inflicted by the poisoned arrows of the Indians. The root washed, pounded fine, and bleached, makes a powder and starch; it is recommended as a proper food for infants, and is gelatinous like salep. It is a native of South America, and is cultivated in the West Indies. . - MARBLE, is a kind of stone, found in great masses, and dug out ef pits or quarries. It is of so hard, compact, and fine a texture, as readily to take a beautiful polish. There are in- finite numbers of different kinds of marble. Some are of one simple colour, as white or black; others variegated with stains, clouds, waves, and veins; but all opaque, excepting the white, which, cut into thin pieces, becomes transparent. Marble is found in considerable quantities in most of the mountainous parts of Europe. Terbyshire is that county of England most abounding in this article. Italy is that part of Europe which produces the most valuable marble. The black and the milk- white marble, coming from Carara, a town in the duchy of Massa, are particularly esteemed. MARBLE, Polishing of, is performed by first rubbing it well with a freestone, or sand, till the strokes of the axe are worn off, then with pumice stone, and afterwards with emery. Florence MARBLE, a kind of hardened mail, is cut into mosaic work, and framed like pictures, which sometimes fetch a high price. If held at a distance from the eye, an inexperienced observer might mistake a slab of Florence marble for a drawing in bistre; for ruins of Gothic buildings, mouldering fragments of cathedrals, and ruinous walls, shattered bastions, and decayed towns, appear in the picture, which on a closer exa- mination offers nothing but irregular spots, lines, and shades. Imitation of MARBLE, is made from plaster of Paris, quick lime, salt, ox-blood, stones of different colours, and pieces of glass. These are all beaten to an impalpable powder, and mixed up to the consistency of a paste by the agency of beer, or some milk. When thoroughly dried in the form which is intended to be given to it, the mass or surface is rubbed with very fine sand-paper, and polished with leather and oil. MARBLING, the method of preparing and colouring the marbled paper. There are several kinds of marbled paper, but the principal difference of them lies in the forms in which the colours are laid on the ground ; some being disposed in whirls or circumvolutions, some in jagged lengths, and others only in spots of a roundish or oval figure. The general man- ner of managing each kind is, nevertheless, the same, being the dipping the paper in a solution of gum tragacanth, or, as it is commonly called, gum dragon; over which the colours, pre- viously prepared with ox-gall and spirit of wine, are first spread. The peculiar apparatus necessary for this purpose, . is a trough for containing the gum tragacanth and the colours, a comb for disposing them in the figure usually chosen ; and a burnishing stone for polishing the paper. The trough may be of any kind of wood, and must be somewhat larger than the sheets of paper for marbling which it is to be employed; but the sides of it need only rise about two inches above the bot- tom, for by making it thus shallow, the less quantity of the solution of the gum will serve to fill it. The comb may be also of wood, and five inches in length, but should have brass teeth, which may be about two inches long, and placed at about a quarter of an inch distance from each other. The burnishing stone may be of jasper or agate; but as those stones are very dear when of sufficient largeness, marble or glass may be used, provided their surface be polished to a greater degree of smoothness. These implements being prepared, the solution of gum tragacanth must be made, by putting a sufficient pro- portion of the gum, which should be white, and clear from all foulness, into clean water, and letting it remain there a day or two, frequently breaking the lumps, and stirring it till the whole shall appear dissolved, and equally mixed with the water. The consistence of the solution should be nearly that of strong gum water used in miniature painting ; and if it appear thicker, water must be added; or if thinner, more of the gum. When the solution is thus brought to a due state, it must be passed through a linen cloth, and being then put into the trough, it will be ready to receive the colours. The colours #. § employed for red are carmine, lake, rose-pink, and vermilion; but the two last are too hard and glaring, unless they be mixed with carmine or lake, to bring them to a softer cast; and with respect to the carmine and lake, they are too dear for common purposes. For yellow, Dutch pink and yellow ochre may be employed: for blue, Prussian blue and verditer may be used.: for green, verdigris, a mixture of Dutch pink and Prussian blue or verditer, in different proportions: for orange, the orange lake, or a mixture of vermilion or red lead with Dutch pink: for purple, rose-pink and Prussian blue. These several colours should be ground with spirit of wine, till they be of a proper fineness; and then at the time of using them, a little fish-gall, or, in default of it, the gall of a beast, should be added, by grinding them over again with it. The proper proportion of the gall must be found by trying them ; for there must be just so much as will suffer the spots of colour, when sprinkled on the solution of the gum tragacanth, to join together, with- out intermixing or running into each other. When every thing is thus prepared, the solution of the gum tragacanth must be poured into the trough, and the colours being in a separate pot, with a pencil appropriated to each, must be sprinkled on the surface of the solution, by shaking the pencil, charged with its proper colour, over it, and this must be done with the several kinds of colour desired, till the surface be wholly covered. When the marbling is proposed to be in spots of a simple form, nothing more is necessary; but where the whirls or snail-shell figures are wanted, they must be made by means of a quill, which must be put among the spots to turn them about, till the effect is produced. The jagged lengths must be made by means of the comb above described, which must be passed through the colours from one end of the trough to the other, and will give them that appearance; but if they be desired to be pointed both ways, the comb must be again passed through the trough in a contrary direction; or if some of the whirls or snail-shell figures be required to be added, they may be yet made by the means before directed. The paper should be previously prepared for receiving the colours, by dipping it over-night in water, and laying the sheets on each other with a weight over them. The whole being thus ready, the paper must be held by two corners, and laid in the most gentle and even manner on the solution covered with the colours, and there softly pressed with the hand, that it may bear every where on the solution. After which, it must be raised and taken off with the same care, and then hung to dry across a proper cord, subtended near at hand for that purpose ; and in that state it must continue till it be perfectly dry. It then remains only to give the paper a proper polish ; in order to which, it is first rubbed with a little soap, and then must be thoroughly smoothed by the glass polishers, such as are used for linen, and called the calendar glasses. After which it should be again rubbed by a burnisher of jasper or agate; or in default of them, of glass ground to the highest polish ; for on the perfect polish of the paper depends in a great measure its beauty and value. Gold or silver powders may be used where desired, along with the colour, and require only the same treatment as them, except that they must be first tempered with gum water. Marbling of books or paper is performed thus:–Dissolve four ounces of gum arabic in two quarts of fair water; then pro- vide several colours mixed with water in pots and shells, and with pencils peculiar to each colour, sprinkle them by way of intermixture upon the gum water, which must be put into a trough or some broad vessel, then with a stick curl them, or draw them out in streaks, to as much variety as may be done. Having done this, hold your book or books close together, and only dip the edges in, on the top of the water and colours, very lightly; which done, take them off, and the plain impression of the colours in mixture will be upon the leaves, doing as well the ends as the front of the book in the like manner. Marbling a book on the covers is effected by forming clouds with aquafortis or spirit of vitriol mixed with ink, and afterwards glazing the covers. See BookBINDING. MARCH. According to common computation, this is con- sidered the third month in the year, but with the Romans it had the honour of being the first. When, however, chronology enumerates the years that have elapsed since the Saviour's incarnation, the calculation always begins with the twenty- M A R. M. A. R. 623 DICTIONARY OF MECHANICAL SCIENCE. fifth day of this month. In this country, prior to the alteration of the style, March stood foremost in the general order, but since that period the honour has been transferred to January. Before the year 1564 the French reckoned the beginning of the year from Easter, so that there were two months of March in one year, which they called March before Easter, and March after Easter; and whenever Easter happened in March, the , beginning of the month was in one year, and the end in another. The first who is said to have divided the year into months was Romulus, who, from Mars, his supposed father, called this month March. Ovid, however, has observed, that the people of Italy used its present name long before the days of Romulus, but its situation was variously placed. It is, however, some- what remarkable, that amidst all its chances March has uni- formly consisted of thirty-one days. March among the ancients was invariably under the protection of Minerva, and, like May, was deemed unpropitious to marriage. The Romans in this month sacrificed to Anna Perenna, began their comitia, and adjusted their farms and leases. During this month the mis- tresses served their servants and slaves at their tables, as the masters did their slaves in the Saturnalia, and the vestals renewed their sacrifice.—For the flower garden, the shrubbery, the kitchen garden, the fruit garden, the greenhouse, the hot- house, and the nursery, this month furnish much employment, the particulars of which may be gathered from any gardener’s calendar. It is the seed time of industry, for the toils of which the subsequent months will fully compensate. MARIGOLD. Calendula Officinalis. An annual plant, usual in the spring. The petals of the flowers are eaten in broths, to which they impart a very pleasant flavour. MARINE, a general name for the navy of a kingdom or state; as also the whole economy of naval affairs, or whatever respects the building, rigging, arming, equipping, navigating, and fighting ships. It comprehends also the government of naval armaments, and the state of all the persons employed therein, whether civil or military. - MARINe Acı D. See MURIATIC ACID. . MARINE Chair, a nachine invented for viewing the satellites of Jupiter at sea, and thereby determining the longitude by their eclipses. - . MARINE Remains, a term used to express the shells of sea- fishes, and parts of crustaceous and other sea-animals, found in digging at great depths in the earth, or on the tops of high mountains. *. MARINE Surveyor, the name of a machine contrived by Mr. H. de Saumerez, for measuring the way of a ship at sea. The machine is in the form of the letter Y, and is made of iron or other metal. At each end of the lines which constitute the an- gle or upper part of the letter, are two pallets, one of which falls in the same proportion as the other rises. The falling or pendent pallet, meeting a resistance from the water as the ship moves, has by that means a circular motion under water, faster or slower, according as the vessel moves. This motion is communicated to a dial within the ship, by means of a rope fastened to the tail of the Y, and carried to the dial. MARINER, a person who gets his living on the sea. MARINER's Compass, an instrument used at sea by mari- ners to direct and ascertain the course of the ship. See CoMPASS. • - MARINES, a body of forces employed in the sea service, under the direction of the lords of the admiralty. MARIOTTE, EDME, an eminent French mathematician and philosopher, was born at Dijon early in the seventeenth cen- tury, and died in 1684. He investigated a number of curious philosophical subjects, such as the collision of bodies; the pressure and motion of fluid ; the nature of vision; the proper- ties of atmospheric air, &c.; on which subject he had several ingenious papers in the Memoirs of the Freneh Academy of Sciences, from vol. i. to vol. x. MARITIME, something relating to, bounded by, or near the sea.—MARITIME Powers, those states which possess harbours, &c. on the sea coasts, and a powerful navy to defend them. MARJORAM, WiNTER. Origanum Vulgare, This is used as a sweet herb, and is a good appendage to the usual ingredi- ents in stuffing, &c. . It is a perennial plant, and propagated by planting out its roots in the spring of the year, | MARJoRAM, Sweet. Origanum Marjorana. This is also used for the same purpose as the last mentioned. It is an annual, and not of such easy culture as the last, requiring to be raised º seeds in an artificial heat. It is usually dried and kept OT US 62. - . - MARK, in Commerce, a certain note which a merchant puts upon his goods, or upon the cask, hogshead, &c. that con- tains them, in order to distinguish them from others, such as a grape, a crow's foot, a diamond, a cross, an asterisk, &c. MARK, or Marc, also denotes a weight used in several states of Europe, and for several commodities, especially gold and silver. In France, the mark is divided into 8 ounces, or 64 drachms, or 192 deniers or penny weights, or 160 esterlins, or 300 mailles, or 640 felins, or 4608 grains. In Holland the mark weight is also called troy weight, and is equal to that of France. When gold and silver are sold by the mark, it is divided into 24 caracts. - . r MARK is also used among us for a money of account, and in some other countries for a coin. The English mark is two-thirds of a pound sterling, or thirteen shillings and four-pence, and the Sootch mark is of equal value in Scotch money of account. The mark-lubs, used at Hamburgh, is also a money of account, equal to one third of the rix-dollar, each mark is divided into 16 sols-lubs. , Mark-lubs is also a Danish coin, equal to 16 sols- lubs. Mark is also a copper and silver coin in Sweden. MARKET, the establishment of public marts or places of buying and selling, with the tolls belonging to it, is one of the king's prerogatives, and markets can only be set up by virtue of the king's grant, or by immemorial usage. All sales and con- tracts of any thing saleable in markets overt, will not only be good between the parties, but binding also upon all persons having any property therein. In London, every shop in which goods are exposed publicly to sale, is market overt for such things only as the owner professes to trade in. If a man buy his own goods in a market, the contract shall not bind him, unless the property had been previously altered by a former sale. - MARL, is a combination of alumine, silex, and alum, and is denominated calcareous, or argillaceous, or siliceous, as the lime, clay, or silex, is most abundant. The calcareous part of marl is frequently composed of shells, whence it frequently has the name of shell marl ; and where these are predominant, it affords an excellent manure for sandy, dry, gravelly, or light lands of any kind. It likewise produces very beneficial effects on mossy and clayey soils; and these effects, if it have been pro- perly applied, will frequently be observable for twelve or fourteen years... Some kinds of marl that contain but a small portion of lime have been successfully employed in the manu- facture of earthenware. Marl is usually found at the depth of from five to nine feet beneath the surface of the ground, and deposited betwixt beds of clay and sand. It is dug out with spades, and in the digging of it in Ireland the workmen not unfrequently meet with the horns of deer and other curious fossils. The usual mode by which persons generally unac- quainted with minerals distinguish this from other substances is, to break a small piece of dry marl into a glass of vinegar, where it will immediately dissolve with considerable effer- vescence; and the briskness of this effervescence will be in proportion to the quantity of lime which it contains. • * MARLINE SPIKE, an iron, tapering to a point, used to sepa- rate the strands of a rope in order to introduce those of an- other, when they are to be spliced or joined evenly without knotting. - w MARLING, the act of winding any small line, as mar-line, spun yarn, twine, &c. about a rope, so that every turn is secur- ed by a kind of knot, and remains fixed in case the rest should be cut through by friction. It is commonly used to fasten slips of canvass on a rope, to prevent its being galled, or to fix the foot of a sail to its bolt rope. ... - - * MARQUE. See Lette Rs of MARQUE. . . . MARQUETRY, or INLA ID Work, is a curious work com- posed of several fine hard pieces of wood, of various colours, fastened in thin slices on a ground, and sometimes enriched with other matters, as silver, brass, tortoise-shell, and ivory. The ground on which the pieces are to be arranged and glued, is usually of well-dried oak, or deal, and is composed of seve- 624 M A R. DICTION ARY OF M A S MECHANICAL SCIENCE. ral pieces, glued together to prevent its warping. The wood to be used in marquetry is reduced into leaves of the thickness of a line, or the twelfth part of an inch, and is either of its na- tural colour, or stained or made black to form the shades, by other methods: this some perform by putting it in sand, heated very hot over the fire; others by steeping it in lime water and sublimate; and others in oil of sulphur. The wood being of . the proper colours, the contours of the pieces are formed ac- cording to the parts of the design they are to represent. The two chief instruments used in this work are a saw and a wooden vice, which has one of its chaps fixed, and the other moveable; which is open and shut by the foot, by means of a oord fastened to a treadle. MARQUIS, a title of honour, next in dignity to that of duke, first given to those who commanded the marches, that is, the borders and frontiers of countries. MARRIAGE, is the lawful conjunction of man and wife ; it was also anciently used to denote the interest of bestowing a ward-or a widow in marriage. Taking marriage in the light of a civil contract, the law treats it as it does all other contracts ; allowing it to be good and valid in all cases where the parties, at the time of making it, were in the first place willing to con- tract; secondly, able to contract; and lastly, actually did con- tract in the proper forms and solemnities required by law. By several statutes, a penalty of one hundred pounds is inflicted for marrying any person without banns or license; but by 26 George II. c. 33, if any person shall solemnize matrimony with- out banns or license, obtained from some person having autho- rity to grant the same, or in any other place than a church or chapel where banns have been usually published, unless by special license from the archbishop of Canterbury, he shall be guilty of felony, and transported for fourteen years. By the same statute it was enacted, that all such marriages were null and void; and much hardship thence resulted. Accordingly, in 1822 and 1823, the legislature was obliged again to inter- fere, and some marriages are now good, although the parties concerned in irregular celebration are liable to punishment. Marriages, according to the laws of any other country, are valid in England, if duly solemnized in another country, as marriages in Scotland are. When a marriage is celebrated by license, affidavit must be made of the parties being above twenty-one, or of the consent of the father or guardian of the party. If the guardian or mother is beyond sea, or insane, the chancellor will proceed upon relation in their stead. Questions have lately arisen, whether this act applies to illegitimate chil- dren, and the civilians have held that it does. Marriages can- not be solemnized between persons within the Levitical de- grees, but if solemnized they are not void till after sentence of the proper court. Promises of marriage, and precontracts, do not prevent the parties from lawfully marrying other persons; but an action lies for a breach of the contract. Marriage- brokage bonds are void in equity, and all contracts in restraint of marriage generally are void; but contracts and legacies upon condition not to marry any particular person, or without pro- per consent, are allowed, under various conditions and re- strictions, some of which involve much difficulty. To marry a woman an heiress forcibly, is a capital felony by 3 Henry VII. c. 2, and 39 Elizabeth, c. 9. A wife cannot leave her husband. If she elope from him, she loses her dower, unless she returns and is reconciled. - MARROW, in Anatomy, a soft oleaginous substance con- tained in the cavity of the bones. MARS, in Astronomy, is one of the planets in our system, the fourth in order from the sun, and consequently the next above our earth. The character by which it is represented is 3, a rude representation of a man holding a sphere. This planet, which is known in the heavens by his red and fiery appear- ance, performs his revolution in his orbit in 6866 23h 30' 39", or 1-881 Julian years. His mean distance from the sun is 1:524, the distance of the earth being taken as unity, which makes his mean distance 142 millions of miles. The eccentricity of his orbit is '093, the semiaxis major being 1. His mean longitude for 1800 was 2° 4° 7'2"-3; the longitude of his perihelion being then 11° 2°24'23"-9; but the line of his apsides has an appa- rent motion according to the order of the signs of 1° 5'-9 in a jear, or 1951’ 3”5 in a century. The orbit of Mars at the same time crossed the ecliptic in 15 18° 1' 18", but the place of the nodes has an apparent motion in longitude, according to the order of the signs, of 26”8 in a year, or 44; 41":5 in a century. The rotation on his axis is performed in 140h 39'21"-3; and his | axis is inclined to the ecliptic in an angle of 59° 41' 49”2. His mean diameter is equal to 4398 miles; consequently he is rather more than #th the size of our earth. His mass, compared with that of the sun considered as unity, is grººm. The proportion of light and heat received by him from the sun, is 43; that received by the earth being considered as unity. He has a very dense but moderate atmosphere ; and he is not accompa- nied by any satellite. As viewed from the earth, the motion of Mars appears sometimes retrograde. The mean arc which he describes in this case is 16°12'; and its mean duration is about 73 days. This retrogradation commences, or finishes, when the planet is not more than 136° 48' from the sun. Mars changes his phases somewhat in the same manner as the moon does from her first to her third quarter, according to his various positions with respect to the earth and the sun; but he never becomes cornicular, as the moon does when near her conjunc- tions. His mean apparent diameter is 9”7; which augments in proportion as the planet approaches its opposition, when it is equal to 29°.2. His parallax is nearly double that of the sun. At the poles of this planet there has been observed bright spots, which are, however, variable in their size and figure; and from the observations of Dr. Herschel, it seems probable that they proceed from snows accumulated in his polar regions during their long winter, these having been observed to decrease and increase, according as they are directed to or from the sun. See Ast Ro NoMY. - - MARSHAL, in its primary signification, an officer who has the command or care of horses; but it is now applied to offi- cers who have very different employments, as earl-marshal, knight-marshal, or marshal of the king's house, &c. MARSHAL of the King's Bench, an officer who has the custod of the King's Bench prison in Southwark. - MARSHAL of the Exchequer, an officer to whom that court com- mits the king's debtors. MARSHALLING A CoAT, in heraldry, is the disposal of several coats of arms belonging to distinct families, in one and the same escutcheon or shield, together with their orna- ments, parts, and appurtenances. MARSHALSEA COURT, is a court of record, originally instituted to hear and determine causes between the servants of the king’s household, and others within the verge; and has jurisdiction within the verge of the court, and of pleas of tres- pass, where either party is of the king's family, and of all other actions personal, wherein both parties are the king's ser- vants, but the court has also the power to try all personal actions, as debt, trespass, &c. between party and party, within the liberty, which extends twelve miles about Whitehall. The judges of this court are, the steward of the king's household, and knight marshal for the time being. It sits every week, so that judgment can be obtained in a fortnight or three weeks. It has jurisdiction of all debts above as well as below 40s. But causes of importance, such as debts above 20l. may be removed into the court of King’s Bench or Common Pleas, by an habeas corpus cum causa. MARSH MARIGOLD. Caltha Palustris. The flower buds, which are opening, are pickled, and are considered as a good substitute for capers. - MARTIN, BeNJAMIN, a very eminent English artist, and mathematician, was born in 1704, but in 1782, in the 78th year of his age, he put a period to his existence. He was author of a great number of ingenious treatises on scientific subjects. MASH, a drink given to a horse, made of half a peck of ground malt put into a pail, into which as much scalding-hot water is poured as will wet it very well: when that is done, stir it about, till by tasting you find it as sweet as honey; and when it has stood till it is lukewarm, it is to be given to the horse. - MASON, a person employed under the direction of an architect, in the raising of a stone building. The chief busi- ness of a mason is to make the mortar, raise the walls from the foundation to the top, with the necessary retreats and perpen- diculars; to form the vaults, and employ the stones as delivered M A S M A S 625 DICTIONARY OF MECHANICAL SCIENCE. to him. When the stones are large, the business of hewing or cutting them belongs to the stone-cutters, though these are frequently confounded with masons: the ornaments of sculp- ture are performed by carvers in stone, or sculptors. The tools or implements principally used by them are, the square, level, plumb line, bevel, compass, hammer, chisel, raallet, saw, trowel, &c. See SQUARE, &c. Besides the common instru- ments used in the hand, they have likewise machines for rais- ing of great burdens, and the conducting of large stones, the principal of which are the lever, pulley, wheel, crane, &c. See LEVER, &c. - MASONS, FREE AND Accepted, a very ancient society, so called, either from some extraordinary knowledge of masonry, they are supposed to be masters of, or because the first foun- ders of the society were persons of that profession. The mem- bers are said to be admitted into the fraternity, by being put into possession of a number of secrets, called the mason's word. MASONRY, in general the art of hewing or squaring stones, and cutting them level or perpendicular, for the uses of build- ing; but in a more limited sense, masonry is the art of assem- bling and joining stones with mortar. MAST, a long round piece of timber, raised perpendicularly on the keel of a ship, upon which are attached the yards, the sails, and the rigging, in order to their receiving the wind necessary for navigation. A mast, according to its length, is either formed of one single piece, which is called a pole mast, or composed of several pieces joined together, each of which retains the name of mast separately. lowest, is accordingly so called. It is ſixed in the ship by an apparatus, (see the articles HULK and SHEERS,) and the foot or keel of it rests in a block of timber called the step, which is fixed upon the keelson. A top mast is raised at the head or top of the lower mast through a cap, and supported by the trestle trees. It is composed of two strong bars of timber, supported by two prominences, which are as shoulders on the opposite sides of the masts, a little under its upper, end ; athwart these bars are fixed the cross trees, upon which the frame of the top is supported. Between the lower mast-head and the foremost of the cross trees, a square space remains vacant, the sides of which are bounded by the two trestle trees. Perpendicularly above this is the foremost hole in the cap, whose after hole is solidly fixed on the head of the lower mast. The top mast is erected by a tackle, whose effort is communicated from the head of the lower mast to the foot of the top mast, and the upper end of the latter is accordingly guided into, and con- veyed up through the holes between the trestle trees and the cap as above mentioned ; the machinery by which it is elevated, or, according to the sea phrase, swayed up, is fixed in the fol- lowing manner: The top rope, passing through a block, which is hooked on one side of the cap, and afterwards through a hole furnished with a sheave or pulley on the lower end of the top mast, is again brought upwards on the other side of the mast, where it is at length fastened to an eye bolt in the cap, which is always on the side opposite to the top block. To the lower end of the top rope is fixed the top tackle, the effort of which being transmitted to the top rope, and thence to the heel of the top mast, necessarily lifts the latter upwards parallel to the lower mast. When the top mast is raised to its proper height, the lower end of it becomes firmly wedged in the square hole (ahove described) between the trestle trees. A bar of wood or iron, called the fid, is then thrust through a hole in the heel of it, across the trestle trees, by which the whole weight of the top mast is supported. See the articles CAP and TRESTLE TREES. Top Gallant MAST, is a mast smaller than the preceding, and raised and secured to its head in the same manner, Top Gallant Royal MAST, is sometimes a yet smaller mast, elevated through irons at the head of the top-gallant mast, but it is more generally a continuation of the latter above the rigging. . It is then termed a pole top-gallant mast, to dis- tinguish it from a stump top-gallant mast, which terminates just above the rigging. - Main MAST, the largest mast in a ship, and stands nearly in the middle between the stem and stern. Fore MAST, is that which stands near the stem, and is next in size to the main mast. 64. A lower mast being the Mizzen MAst, the smallest mast, and stands about half way between the main nast and the stern. - Made MAST, a mast built or composed of several pieces of timber, in contradistinction to one consisting of a single stick or piece. The counter mizzen, in large vessels and galleons, is the stern. Rough MAST, denotes a spar fit for making a mast. Besides the parts already mentioned in the construction of masts with respect to their length, the lower masts of the largest ships are composed of several pieces united into one body. As these are generally the most substantial parts of various tiers, a mast formed by this assemblage, is justly esteemed much stronger than one consisting of any single trunk, whose internal solidity may be very uncertain. The whole is secured with their sides or faces close to each other, by several strong hoops of iron, driven on the outside of the mast, where they remain at proper distances. The principal articles to be considered in equipping a ship with masts are, 1st. The number: 2d. Their situation in the vessel ; and 3d. Their height above the water. The masts being used to extend the sails by means of their yards, it is evident, that if their number were multiplied beyond what is necessary, the yards must be extremely short, that they may not entangle each other in working the ship, and by consequence their sails will be very narrow, and receive a small portion of wind. If, on the contrary, there is not a suffi- cient number of masts in the vessel, the yards will be too large and heavy, and cannot be managed without difficulty. There is a mean between these extremes, which experience and the general practice of the sea have determined, by which it appears, that in large ships every advantage of sailing is retained by three masts and a bowsprit. - Among the ancient Grecians, every ship had several masts: we are nevertheless informed by Aristotle, that at first there was only one mast, which being fixed in the middle of the ship, the hole into which the foot of it was inserted they called piscoöpum, in Latin modius, and in English the step. The parts of the mast were these : irrepva, or the foot; Awaç, to which the sail was fixed ; Kapknotov, the pulley by which the ropes were turned round; 9apaktov, built in the manner of a turret, for sol- diers to stand upon, and cast their darts. Above this was a piece of wood called trptov, on the extremity of which hung a riband, which was in continual motion, turning round with the wind, and termed in English the vane. With regard to the moderns, all ships, properly so called, are, as already observed, furnished with three masts. Those which have only two or one mast are not called ships by seamen, but vary their names according to the method of rigging. Of two masts, there are snows, brigs, bilanders, ketches, busses, schooners, and her- maphrodites, among the English. Among the Spaniards and Italians, settees, barco-longas, feluccas, &c. Those of one mast are sloops, tartans, bean-cods, shallops, &c. The most advantageous position of the masts is undoubtedly that from whence there results an equilibrium between the resistance of the water on the body of the ship on one part, and of the direction of their effort on the other. By every other position this equilibrium is destroyed, and the greatest effort of the masts will operate to turn the ship horizontally about its direction, a circumstance which retards her velocity. It is counterbalanced indeed by the helm, but the same inconve- nience still continues; for the force of the wind having the resistance of the helm to overcome, is not entirely employed to push the vessel forward. The axis' of the resistance of the water should then be previously determined, to disco- ver the place of the main mast, in order to suspend the efforts of the water equally, and place the other masts so as that their particular direction will coincide with that of the main mast. The whole of this would be capable of a solution, if the figure of the vessel were regular, because the point about which the resistance of the water would be in equilibrium, might be discovered by calculation.; but when the real figure of the ship is considered, these flattering ideas will instantly vanish. This observation induced M. Saverien to employ a * * * * : mechanical method to discover the axis of resistance of the water, which he apprehended might be used with success. The exact height of the masts in proportion to the form and | size of the ship, remains yet a problem to be determined. The 7 U - 626 M A. S M A s DICTIONARY OF MECHANICAL SCIENCE. more the masts are elevated above the centre of gravity, the greater will be the surface of the sail which they are enabled to present to the wind; so far an additional height seems to be advantageous. But this advantage is diminished by the cir- cular movement of the mast, which operates to make the vessel stoop to its effort; and this inclination is increased in propor- tion to the additional height of the masts ; an inconvenience which it is necessary to guard against; thus what is gained upon one hand is lost upon the other. To reconcile these diſſerences, it is certain that the height of the mast ought to be determined by the inclination of the vessel, and that the point of her greatest inclination should be the turn of this height above the centre of gravity. See the article TRIM. With regard to the general practice of determining the height of the masts, according to the different rates of the ships in the royal navy, see also the article SAIL. In order to secure the masts, and counterbalance the strain they receive from the effort of the sails impressed by the wind and the agitation of the ship at sea, they are suspended by several strong ropes extended from their upper ends to the outside of the vessel, called shrouds, (see that article.) They are further supported by other ropes, stretched from their heads towards the forepart of the vessel. See the article RIGGING. . In the British navy, masts are pro- portioned to the extreme breadth of the ship from out to out. The main and fore mast in all ships down to 60 guns, one inch diameter to every yard in length. For 50 and 40 guns, §th of an inch diameter to one yard in length. For 24 guns, #ths of an inch in diameter to one yard in length. Aſí top masts are nine-tenths of an inch in diameter to one yard in leagth. The fore-top mast, as large as the main-top mast. The top-gallant mast one inch to a yard. The mizzen mast # of an inch to one yard in length. The mizzen top-mast five- sixths of an inch to one yard in length. The bowsprit an inch and a half to one yard. The jibboom seven-eighths of an inch to a yard. The proportion for masting ships in the merchant's service is generally regulated by the judgment and experience of the commander. - . General Proportion for the Length of Masts. 748 : 100 Guns, 756 : 90 tº 753 : 80 - 1000 : breadth in feet ::< 741; S-Main mast in yards 70 and 60, 740: - 50 - 747 : 44 760 : 24 1000 : main mast : : ... $ 39% }: ſº $ 100, 90, 80, and } º * Ore mast . . • * * * * * R all the rest. 1000 : main mast ::. . . . : A • 100, 90, 80, and Q ; : ; mizzen mast...... } all the rest. 1000 main mut: .... } * : * bowsprit ......... $ 100.90, 80, and §: : $ owspri * * * all the rest. * * 100, 90, 80, 1000 : main mast ::. . . . & 605: }** mast . . . . K 70, '60' 50, - ; $ 40, 24. 1000 : main top mast :: “$999; }: t tº } 100, 90, 80, and P } #} ore top mast. . . . . . all the rest. 1000 : main top laast :: } 710. } s ... $ 100,90, 80, and s P #; * i. top mast. . . & all the rest. 1000 : main top mast :: } 3U : sº st 5 100, 90, 80, and p ;: º: top gall, mast } all the rest. 1000 : fore top mast : : } 3 ºf $ 100, 90, 80, and p 505 : 5 ore top gall. mast & all the rest. The Dimensions of Masts for East India Ships are, Length in Feet. Main Mast, ........... 80 • * * * * * * * * * 24} Top Mast, . . . . . . . . . . . . 50 * * * * * * * * * * :15 Top gallant Mast, ... . . . 28 * * c e a c e o 'º 8 Fore Mast, ............ 72 9 8 & 9 s s e e s e 24. Top Mast, ............ 48 .......... 16° Top-gallant Mast, ...... 25 tº e s e e º 'º e º ºs 7% Mizzen Mast, .......... 70 * * * * * e º e º ge 17 Top Mast, ............ 36 * * * 0 e º e s tº e 10 Bowsprit, ...... . . . . . . . 50 * & © tº e s ∈ tº e g 25 Armed MAST, is a mast that is made of more than one tree. ... To MAST a Ship, to hoist her masts into her by means of a sheer, or of a sheer hulk. See these articles. - Diameter in Inches, - Spending a MAst, is when it is broken by foul weather. Springing a MAST, is when it is cracked in any place. Over Masted, or Taut Masted, is said of a ship whose masts are too tall or too heavy, which makes her lie too much down by the wind, and labour too much a-hull. Under Masted, or Low Masted Ships, are such whose masts on the contrary are too short, or light; in which case she can- not bear so great a sail as should give her true way. Clint’s Ballanced MAsts for Sailing Vessels.-The object of this invention is, by having the mast, rigging, &c. placed in a ballasted cassoon or box of a semicircular shape, suspended fore and aft on pins, &c. in two deck beams; that the mast, &c. shall alone be acted on by the wind, and (as shewn by the figure,) leave the vessel itself perfectly upright, when close, hauled upon a wind. - . Explanation of the figures. Fig. 1, a, a section of the hull of the vessel, b a section of the ºffº swinging cassoon, with the stays, pen- nants, &c. fastened to it, and the box containing the ballast; c, the point of F. suspension on the deck beams. Fig. 2 is a plan of the sailing boat, contain- Tººla ing the cassoon b, and swinging upon the pivots c c. Mechanical skill will be requisite in the construction of the parts for strength, to sustain the bal- last : pins of three inches diameter would sustain about thirty or forty tons. The forestay is to be hooked to the stern head. The advantages proposed by Mr. Clint by this construction are first, perfect safety; as he considers it impossible that a vessel on this construction could capsize. Secondly, the vessel being always upright, is constantly on what is termed her lines, and is always in her trim ; whereby she will sail faster, and go better to windward. Thirdly, the support for the mast, &c. being within the vessel, the width of beam may be diminished to one half, whereby the vessel will acquire length, and go faster. Fourthly, the ballast being suspended in the air is of more effect than ballast placed in the bottom ; the latter being identified with the vessel, and the water loses as much of its weight as its specific gravity; while the former being indepen- dent of the water, and maintaining all its weights, a much smaller quantity will be required to steady the mast, and the vessel itself requiring none, a great degree of buoyancy is obtained. The truth of this position may be ascertained by holding in the hand a weight in the air, and holding it in the water. A vessel on this principle has been constructed, of the following dimensions:—Length 25 feet, breadth 5 do. depth 2} do. ; space for the cassoon 5 feet square, cassoon a good fit to the same size. She was rigged with one mast of nineteen feet, carrying a gaff and foresail, and containing fifty yards or cloth. To those conversant with sailing, this quantity of rig- ging must appear very extraordinary ; but her capacity to carry it results from the principle mentioned in the position. This invention is intended only for such vessels as are not employed in the carrying of cargoes, of which class are revenue cutters, pleasure and pilot boats, cartels, nor is it intended for vessels above seventy tons, which may have the box decked in. When the vessel is launched before the places of the masts are determined, extend a rope A B, in the following figure, from cº- S yº. A . A. 3B § S º § S- 2 § N § N § § 2/*} ==S-SS: &- :*: … * & .* ºš. º º ſº zºsºstseasº * :Sºss- s===-º ºrg º Jº |- - ----- E lº lºſ. -* * the head to the stern. To the extremities A and B attach twº. M A S SCIENCE. M A T 627 DIC'I'ION ARY OF MECHANICAL other ropes AD, BC, and apply to the other ends of these ropes two mechanical powers, to draw the ship according to the direction B C, parallel to itself. The whole being thus dis- posed, let a moveable tube Z, fixed upon the rope A, B, have another rope Z R attached to it, whose other end communi- cates with a mechanical power R equal to the two other powers D and C. This last being applied to the same vessel, in such manner as to take off the eſſects of the two others by sliding ſupon the rope A B, so as to discover some point Z., by the parallelism of the ropes A D, B C, feebly extended with the rope Z R.; the line Z R will be the axis of the equilibrium of the water's resistance, and by consequence the main mast should be planted in the point Z. The figures E, E, E, are three windlasses on the shore, by which this experiment is applied. With regard to the situation of the other masts, it is necessary in the same manner to discover two points; so that the direction of the two mechanical powers operating, will be parallel to the axis of resistance R. Z, already found. MASTER of ARts, is the first degree taken up in foreign universities, and for the most part in those of Scotland ; but the second in Oxford and Cambridge, candidates not being admitted to that honour till they have studied ‘seven years in the university. MAster in Chancery. The masters in Chancery are assist- ants to the Lord Chancellor and Master of the Rolls; of these there are some ordinary and others extraordinary : the mas- ters in ordinary are twelve in number ; some of whom sit in court every day during the term, and have referred to them in- terlocutory orders for stating accounts, and computing dam- ages, and the like ; and they also administer oaths, take affida- vits, and acknowledgments of deeds and recognizances. The masters extraordinary are appointed to act in the country, be- yond ten miles' distance from London. MASTER of the Faculties, an officer under the archbishop of Canterbury, who grants licenses and dispensations. MASTER of the Horse, a great officer of the crown, who orders all matters relating to the king’s stables, races, breed of horses, &c. MAster of the Ordnance, a great officer who has the chief command of the king’s ordnance and artillery. MAst ER of the Rolls, a patent officer for life, who has the cus- tody of the rolls of parliament, and patents which pass the great seal, and of the records of chancery, &c. In absence of the chancellor, he sits as judge in the court of chancery ; at other times he hears causes in the rolls chapel, and makes orders; he hath a writ of summons to parliament. MAster of a Ship, the same with captain in a merchantman; but in a king's ship he is an officer who inspects the provisions and stores, takes care of the rigging and of the ballast, and gives directions for stowing the hold ; and navigates the ship under the directions of his superior officer. MIASTER at Arms, in a king's ship, an officer who daily by turns, as the captain appoints, is to exercise the petty officers, and ship's company, to place and relieve sentinels, to see the candles and fire put out according to the captain's orders, to take eare the small arms are kept in good order, and to observe the directions of the lieutenant at arms. MAster of the Temple, since the dissolution of the order of the Templars, the spiritual guide and master of the Temple is so called, which was the denomination of the founder and his successors. MASTER of the Wardrobe, an officer under the lord chamber- lain, who has the care of the royal robes, &c. MASTERS and Serv ANTs. In London and other places, the mode of hiring is by what is commonly called a month's warn- ing or a month's wages; that is, the parties agree to separate on either of them giving to the other a month's notice for that purpose, or, in lieu thereof, the party requiring the separation to pay or give up a month's wages. But if the hiring of a ser- vant be general, without any particular time specified, it will be construed to be a hiring for a year certain; and in this case, if the servant departs before the year, he forfeits all his wages. And where a servant is hired for one year certain, and so from year to year as long as both parties shall agree, and the servant enter upon the second year, he must serve out that year, and is not merely a servant at will after the first year. If | will be answerable. a woman servant marry, she must nevertheless serve out her term. If a servant be disabled in his master's service, by an injury received through another's default, the master may re- cover damages for loss of his service. And a master may not | only maintain an action against any one who entices away his servant, but also against his servant; and if, without any enticement, a servant leaves his master without just cause, an action will lie against another, who retains him with a know- ledge of such departure. A master has a right to expect and exact fidelity and obedience in all his lawful commands; and to enforce this, he may correct his servant in a reasonable man- ner. In defence of his master, a servant may justify assault- ing another, and though death should ensue, it is not murder, in case of any unlawful attack upon his master’s person or pro- perty. Acts of the servant are in many instances deemed acts of the master; and he is answerable for them, when they are pursuant to his authority. If a servant commit an act of tres- pass by command or encouragement of his master, the master But in so doing, his servant is not excus- ed, as he is bound to obey the master in such things only as are honest and lawful. If a servant of an innkeeper robs his master's guest, the master is bound to make good the loss. Also, if a waiter at an inn sell a man bad wine, by which his health is impaired, an action will lie against the master. In like man- ner, if a servant be frequently permitted to do a thing by the tacit consent of his master, the master will be liable. If a ser– vant is usually sent upon trust with any tradesman, and he takes goods in the name of his master, upon his own account, the master must pay for them ; and also, if he is sent some- times on trust, and at other times with money. But if a man usually deals with tradesmen himself, or constantly pays them their money, he is not answerable for what his servant may take up in his name. So it is, if the master never had any per- sonal dealings with the tradesman, but the contracts have al- ways been between the servant and the tradesman, and the master has regularly given his servant money for payment of every thing had on his account, the master shall not be charged. Or if a person forbid his tradesman to trust his servant on his account, and he continues to purchase upon credit, he is not liable. The act of a servant, though he has quitted his master’s service, has been held to be binding upon the master, by reason of the former credit given him on his master’s account, and its not being known to the party trusting that he was discharged. The master is also answerable for any injury arising by the fault or neglect of his servant, when executing his master’s bu- siness. If a smith's servant lame a horse whilst shoeing him, or the servant of a surgeon make a wound worse, an action for damages will lie against the master, and not against the servant. A master is likewise chargeable for any nuisance occasioned by his servants, to the damage or annoyance of any individual or the common nuisance of his majesty’s subjects. A servant is not answerable to his master for any loss which may happex, without his wilful neglect, but if he be guilty of fraud or gross negligence, an action will lie against him by his master. A master is not liable in trespass for the wilful act of his servant, as by driving his master's carriage against another, without the direction or assent of his master, no person being in the car- riage when this act was done. But he is liable to answer for any damage arising to another from the negligence or unskil- fulness of his servant acting in his employ, as for negligently driving against another. - MASTICATION, in Medicine, the action of chewing, or of agitating the solid parts of our food between the teeth, by means of the motion of the jaws, the tongue, and the lips, where- by it is broken into small pieces, impregnated with saliva, and so fitted for deglutition and a more easy digestion. MASTICH, in the materia medica, when pure is in the form of little round drops or tears of a very pale amber. When slightly warmed, this resin has a faint and rather pleasant odour, which becomes stronger and more grateful when it is melted. In Turkey, mastich is in great request among women as a masticatory. In other countries it is employed medicinal- ly in fumigations; and by painters and other artists, in the composition of the tougher kinds of varnishes. MATCH, a kind of rope slightly twisted, and prepared to retain fire for the uses of artillery, mines, fireworks, &c. 628 M A T M A 'T DICTIONARY OF MECHANICAL SCIENCE. MATCHING, in the wine trade, the preparing vessels to preserve wines and other liquors, without their growing sour or vapid. The method of doing it as follows:–Melt brimstone in an iron ladle, and when thoroughly melted dip into it slips of coarse linen cloth ; take these out, and let them cool; this the wine coopers call a match. Take one of these matches, set one end of it on fire, and put it into the bung-hole of a cask; stop it loosely, and thus suffer the match to burn nearly out; then drive in the bung tight, and set the cask aside for an hour or two. At the end of this time examine the cask, and you will find that the sulphur has communicated a violent pungent and suffocating scent to the cask, with a considerable degree of acidity, which is the gas and acid spirit of the sul- phur. The cask may after this be filled with a small wine which has scarce done its fermentation; and bunging it down tight it will be kept good, and will soon clarify: this is a com- mon and very useful method, for many poor wines could scarce be kept potable even a few months without it. MATERIA MEDICA. The materia medica includes all those substances which may contribute to the restoration of health. MATHEMATICS, from Mathema, a science. The science which contemplates whatever is capable of being numbered or measured. Mathematics are commonly distinguished into spe- culative and practical, pure and mixed. Speculative Mathema- ties, is that which barely considers the properties of things; and Practical Mathematics, that which applies the knowledge of those properties to some uses in life. Pure Mathematics is that branch which considers quantity abstractedly, and without any relation to matter or bodies, as Arithmetic and Geometry: Miagd Mathematics, considers quantity as subsisting in material being; for instance, length in a pole, depth in a river, height in a tower, &c. Pure Mathematics, again, either considers quantity as abstract or discrete, these words are synonymous in this sense, and so computable as Arithmetic ; or as concrete, and so measurable as Geometry. Mia!ed Mathematics is very extensive, and is distinguished by various names, according to the different subjects it considers, and the different views in which it is taken, such as astronomy, geography, optics, hydro- statics, navigation, &c. : * MATRICARIA PARTHENIUM. Common wild Feverfew. The Land Flowers.-Simon Pauli relates, that he has experienced happy effects from it in obstructions of the uterine evacuation, I have often seen, says he, from the use of a decoction of matricaria and chamomile flowers with a little mugwort, hys- teric patients instantly relieved, and the patient from a lethar- tic state brought as it were to life again. Matricaria is like- wise recommended in sundry other disorders, as a warm stimulating bitter: all that bitters and carminatives can do, says Geoffroy, may be expected in this. It is undoubtedly a medicine of some use in these cases, but not perhaps equal to chamomile flowers alone, with which the matricaria agrees in sensible qualities, except in being weaker. MATTER, in Philosophy, whatever is extended, and capa- ble of making resistance; hence, because all bodies, whether solid or fluid, are extended and do resist, we conclude that they are made up of matter. That matter is one and the same thing in all bodies, and that all the variety we observe arises from the various forms and shapes it puts on, seems very pro- bable, from a general observation of nature in the generation and destruction of bodies : thus, water rarefied by heat becomes vapour ; a great collection of which forms clouds; these con- densed descend in hail or rain ; part of this collected on the earth constitutes rivers; another part mixing with the earth, enters into the roots of plants, and expands itself into various species of vegetables. In each vegetable it appears in one shape in the root, another in the stalk, another in the ſlowers, &c. Hence various bodies proceed; from the oak, houses, ships, &c.; from hemp and flax we have thread; thence our various kinds of linen; these degenerate into rags, which receive from the mill the various forms of paper, &c. § * ... According to Newton, it seems probable that God in the be- ginning formed matter into solid, massy, impenetrable, move- able particles, or atoms, of such sizes and figures, and with such other properties, and in such proportion to space, as most conduced to the end for which he formed them; these primi- on them may be changed. tive particles being solids, are incomparably harder than any porous bodies compounded of them, no ordinary power being able to divide what God himself made one in the first creation. While these particles continue entire, they may compose bodies of the same nature and texture in all ages; but should they wear away, or break in pieces, the nature of things depending Water and earth composed of old worn particles and fragments of particles, would not be of the same nature and texture now, with water and earth composed of entire particles in the beginning ; and therefore, that nature may be lasting, the changes of corporeal things are to be placed only in the various separations and new associations of motions of these permanent particles,compound bodies being apt to break, not in the midst of solid particles, but where those particles are laid together and only touch in a few minutes. Dr. Berkeley argues against the existence of matter itself, and endeavours to prove that it has no existence out of the mind. Some late philosophers have advanced a new hypothesis concerning the nature and essential properties of matter, as Boscovich, in his “Theoria Philosophiæ Naturalis;” who supposes that matter is not impenetrable, but consists of physical points only, endued with powers of attraction and repulsion, taking place at different distances; that it is surrounded with various spheres of attraction and repulsion, in the same manner as solid matter is supposed to be. Provided therefore any body move with a sufficient degree of velocity, or have a sufficient momentum to overcome any power of repulsion that it may meet with, it will find no difficulty in making its way through any body whatever. If the velocity of such body in motion be sufficiently great, Bos- covich contends that the particles of any body through which it passes, will not even be moved out of their place by it. With a degree of velocity something less than this, they will be con- siderably agitated, and ignition might perhaps be the conse- quence, though the progress of the body in motion would not be sensibly interrupted; and with a still less momentum, it might not pass at all. Dr. Priestley, and some others of our own country, entertained the same opinion. In conformity to this hypothesis Priestley maintains that matter is not that inert substance that it has been supposed to be ; that, powers of at- traction or repulsion are necessary to its being; and that no part of it appears impenetrable to other parts. Accordingly, he defines matter to be a substance possessed of the property of extension, and of powers of attraction or repulsion, not dis- tinct from matter, and foreign to it, but absolutely essential to its nature and being ; so that when bodies are divested of these powers they become nothing. In another place, Priestley has given a somewhat different account of matter; according to which it is only a number of centres of attraction and repulsion, or, more properly, of centres not divisible, to which divine agen- cy is directed; and as sensation and thought are not incompa- tible with these powers, solidity or impenetrability, and con- quently a vis inertia, only having been thought repugnant to them, he maintains that we have no reason to suppose that there are in man two substances absolutely distinct from each other. But Dr. Price, in a correspondence with Dr. Priestley, published under the title of “A Free Discussion of the Doc- trines of Materialism and Philosphical Necessity,”'iz78, sug- gested a variety of unanswerable objections against this hypo- thesis of the penetrability of matter, and against the conclu- sions that are drawn from it. The vis inertia of matter is the foundation of all that is demonstrated by natural philosophy concerning the laws of the collision of bodies. This is the foun- dation of Newton's philosophy, and especially of his three laws of motion. Solid matter has the power of acting on other matter by impulse ; but unsolid matter cannot act at all by impulse ; and this is the only way in which it is capable of acting by any action that is properly its own. If it be said that one particle of matter can act upon another without con- tact and impulse, or that matter can, by its own proper agency, attract or repel other matter which is at a distance from it, then a maxim hitherto universally received must be false, that “ No- thing can act where it is not.” Newton, in his letters to Bentley, calls the notion that matter possesses an innate power of attrac- tion, or that it can act upon matter at a distance, and attract and repel it by its own agency, an absurdity into which he thought no one could possibly fall. And in another place he M A X M A Y DIG FIONARY OF MECHANICAL scIENCE. 629 expressly disclaims the notion of innate gravity, and has taken pains to shew that he did not take it to be an essential property of bodies. By the same kind of reasoning pursued, it must ap- pear that matter has not the power of attracting and repelling; that this power is the power of some foreign cause, acting upon matter according to stated laws; and consequently that attrac- tion and repulsion not being actions, much less inherit qualities, of matter; as such, it ought not to be defined by them. And if matter has no other property, as Dr, Priestley asserts, than the power of attracting and repelling, it must be a non-entity; because this is a property that cannot beloag to it. . Besides, all power is the power of something, and yet ifmatter is nothing the very idea of it is a contradiction. If matter be not solid extension, what can it be more than mere extension. Farther, matter that is not solid, is the same with pore ; and therefore it cannot possess what philosophers mean by the momentum or force of bodies, which is always in proportion to the quantity of matter in bodies void of pore. MATRIX, or Mother Earth, the stone in which metallic orcs are found enveloped. MATROSSES, are soldiers in the train of artillery, who are next to the gunners, and assist them in loading, firing, and spunging the great guns. * MAUNDAY. THURSDAY, is the Thursday in the passion week; called Munday or Mandate Thursday, from the com- mand which our Saviour gave his apostles to commemorate him in the Lord’s Supper, which he this day instituted; or from the new commandment that he gave them, to love one another, after he had washed their feet in token of his love to th French mathematician and philosopher, was born at Malo, in 1698, and was there privately educated, till he attained his 16th year, when he was placed under the celebrated professor of philosophy, M. Le Bland, in the college of La Marche, at Taris; while M. Guisnee, of the Academy of Sciences, was his instructor in mathematics. In 1723 he became a member of the French Academy, and five years after a fellow of the Royal Society of London. In 1736 he was sent, with other aca- demicians, to the North, to determine the figure of the earth, which service they performed with reputation. At the invita- tion of the Prince of Prussia, afterwards Frederic the Great, he went to Berlin, and was appointed president and director of the Academy there. He died at Basil, in 1759. MAXILLA. See ANATOMY. MAXIM, an established proposition or principle, in which sense it denotes much the same with axiom. See AXIOM. MAXIMA et MINIMA, in Analysis and Geometry, are the greatest and least value of a variable quantity; and the method of finding these greatest and least values, is called the Metho- dus de Maazimis et Minimis, which forms one of the most inte- resting inquiries in the modern analysis. This subject was con- sidered geometrically by some of the most ancient mathema- ticians, particularly by Apollonius, in the 5th book of his Conics, and there are still a few problems of this kind, which succeed better by the geometrical than by the analytical method ; their number, however, is very limited, compared with those which may be elegantly formed with analysis. The method of maxima et minima, according to the analytical doctrine, first arose at the beginning of the seventeenth century, after the invention of Des Cartes for expressing the properties of curve lines by means of algebraical equations, and classing them into different orders according to the degree of the equation which expressed the relation between the abscis and ordinate. Besides the method of Des Cartes, we have also those of Fermat, Hudde, Huygens, Sluze, and some others, which are now all supplanted by the general and elegant method of fluxions. MAXIMUM, in Mathematics, denotes the greatest quantity attainable in a given case. If a quantity conceived to be gene- rated by motion, increases or decreases till it arrives at a cer- tain magnitude or position, and then, on the contrary, grows less or greater, and it be required to determine the said mag- nitude or position, the question is called a problem de maxi- mis et minimis. Thus let a point m move uniformly in a right line, from A towards B, and let another point n move after it, with a velocity either increasing or decreasing, but so that it C DIN, MAUPERTUIS, PETER Louis MoRCEAU De, a celebrated may at a certain position, D, become equal to that of the for- mer point m, moving uniformly. D. C A { + B. m. 7%, This being premised, let the motion of n be first considered as an increasing one; in which case the distance of n behind m will continually increase, till the two points arrive at the con- temporary positions C and D ; but afterwards it will again de- crease; for the motion of n till then being slower than at D, it is also slower than that of the preceding point m, (by the hypo- thesis,) but becoming, quicker afterwards than that of m, the distance m n (as has been already said) will again decrease, and therefore as a maximum, or the greatest all, when the ce- lerities of the two points are equal to each other. But if n ar- rives at D with a decreasing celerity, then its motion being first swifter, and afterwards slower than that of m, the distance | of m n will first decrease and then increase, and therefore is a minimum, or the least of all, in the forementioned circumstance. Since then the distance m n is a maximum or a minimum, when the velocities of m and n are equal, or when the distance in- creases as fast through the motion of m, as it decreases by that of m, its fluxion at that instant is evidently equal to nothing. Therefore as the points m and n may be conceived such that their distance m n may express the measure of any variable quantity whatever, it follows, that the fluxion of any variable quantity whatever, when a maximum or a minimum, is equal to nothing. The rule therefore to determine any flowing quantity in an equation proposed, to an extreme value, is: having put the equation into fluxions, let the fluxion of that quantity whose extreme value is sought, be supposed equal to nothing; by which means all those members of the equation in which it is found will vanish, and the remaining ones will give the determination of the maximum or minimum required. See FLUXIONs. MAY. Reckoning from January, this is the fifth month in our year; or the third, if we begin, as the ancient Romans did, with March. By Romulus it was called Maius, out of respect to the senators and nobles of his city. Some, however, have thought that the name is derived from Maia, the mother of TMercury, to whom sacrifices were offered on the first day of this month. May was supposed by the ancients to be under the immediate protection of Apollo. In it they kept the festi- val of Bona Dea; also that of the goblins called Lemuria, and the ceremony of the expulsion of the kings. In this month the sun enters Gemini, the earth teems with vegetative life, the trees are adorned with blossoms, and the gardens are perfumed with the fragrance of flowers. The Kalendar of Animated nature for May, round London, brings the cuckoo and turtle-dove, the glow-worm, and the fern owl, or goatsucker.—In Vegetable nature, the lily of the valley, the tulip-tree, the oak, ash, sweet chestnut, barberry, and lime trees ſlower and blossom. Rye is now in the ear.—In the Kitchen garden, sow, protect, pro- pagate, plant, transplant, attend to routine culture, and destroy insects and vermin. In the hardy fruit department, plant, plune, and attend to routine culture. In the culinary hot- house department attend to glass-casing, the pinery, and forcing department. Much is to be done in the flower garden, open ground and hot-house departments; as also in the plea- sure ground and shrubbery. Fell old oaks and other barking trees, and prune oaks, because the wood heals quicker while the sap is flowing.—Of fish we have the same kinds in season this month as in April, which see ; so also of meat, and poul- try. Vegetables are more abundant, and to our winter stores of fruits there are now added strawberries, cherries, melons, gooseberries, and currants. MAY Weed, in Botany, is a troublesome weed, which resem- bles wild chamomile. It is a trailing perennial plant, the branches of which put forth roots at every joint. By these means, and by scattering its seeds in the fields long before the corn is ripe, it multiplies without the possibility of prevention. It flowers in May, and from this circumstance derives its name. It is chiefly extirpated by summer fallowing, and by burning the roots collected by good harrowing. Many other weeds, together with various fruits, flowers, and natural productions 7 X. - 630 M E A M E A DICTION ARY OF MECHANICAL SCIENCE. bear the name of May, from their appearing during this month in the greatest state of perfection. MAYER, TobiAs, a German astronomer and mechanician, was born at Manpach, in Wirtemberg, in the year 1723; and in 1751 he was nominated mathematical professor at the univer- sity of Gottingen, and soon after was admitted a member of the Royal Society in that town. From this time every year of his life was distinguished by discoveries in geometry and astro- nomy. He invented many useful instruments; he applied himself to study the theory of the moon; he extended his ob- servations to the planet Mars and the fixed stars, determining the places of the latter, and ascertaining that they possess a certain degree of motion relative to their respective systems. Towards the close of his short life the magnetic needle eugaged his attention, to which he assigned more certain laws than those before received. To all his pursuits he applied with such indefatigable assiduity, that he died literally worn out with labour, in 1762, at the age of thirty-nine years. . MEAD, a wholesome, agreeable liquor, prepared with honey and water. One of the best methods of preparing mead is as follows:—Into twelve gallons of water put the whites of six eggs; mixing these well together, and to the mixture adding twenty pounds of honey. Let the liquor boil an hour; and when boiled, add cinnamon, ginger, cloves, mace, and rose- mary. As soon as it is cold, put a spoonful of yeast to it, and turn it up, keeping the vessel filled as it works; when it has done working, stop it up close ; and, when fine, bottle it off for UIS 6. choose the whitest, purest, and best tasted honey, and to put it into a kettle with more than its weight of water: a part of this liquor must be evaporated by boiling, and the liquor scummed, till its consistence is such, that a fresh egg shall be supported on its surface without sinking more than half its thickness into the liquor; then the liquor is to be strained and poured through a funnel into a barrel; this barrel, which ought to be nearly full, must be exposed to a heat as equable as possible, from 20 to 27 or 28 degrees of Mr. Reaumur's thermometer, taking care that the bung-hole be slightly covered, but not closed. The phenomena of the spirituous fermentation will appear in this liquor, and will subsist during two or three months, according to the degree of heat; after which they will diminish and cease. During this fermentation, the barrel must be filled up occasionally with more of the same kind of liquor of honey, some of which ought to be kept apart, on purpose to replace the liquor which flows out of the barrel in froth. When the fermentation ceases, and the liquor has become very vinous, the barrel is then to be put into a cellar, and well closed; a year afterwards, the mead will be fit to be put into bottles. Mead is a liquor of very ancient use in Britain. See FEAST. ME AD, Dr. Richard, a celebrated English physician, was born at Stepney near London, where his father, the Rev. Mr. Matthew Mead, had been one of the two ministers of that parish ; but in 1662 was ejected for nonconformity, but con- tinued to preach at Stepney till his death. As Mr. Mead had a handsome fortune, he bestowed a liberal education upon 13 children, of whom Richard was the eleventh ; and for that pur- pose kept a private tutor in his house. - MEADOW, in its general signification, means pasture or grass lands, annually mown for hay ; but it is more particularly applied to lands that are so low as to be too moist for cattle to graze upon them in winter without spoiling the sward. MEADow-sweet. Spiraea Filipendula.-The roots of this, in Sweden, are ground and made into bread. - MEAL, the flour of grain. The colour and weight are the two things which denote the value of meal or flour; the whiter and heavier, other things being alike, the better it always is. MEAN, in general, denotes the middle between two ex- tremes: thus we say, the mean distance, mean proportion, &c. MEAN, Arithmetical, is half the sum of the two extremes, as . º - . 6 4 is the arithmetical mean between 2 and 6; for ** E 4 MEAN, Geometrical, is the square root of the rectangle, or product of the two extremes, thus, VT 3: 9 = 2x/ 9 = 3. To find two mean proportionals between two extremes: multiply each extreme by the square of the other, then extract the cube The author of the Dictionary of Chemistry directs to root out of each product, and the two roots will be the mean proportionals required. Required two proportionals between 2 and 16, 2 × 2 × 16 E 64, and *M 64:4. Again, 82/2 x 16°E *N/ 512 = 8. 4 and 8, therefore, are the two mean proportionals sought. - Harmonical MEAN, is double a fourth proportional to the two extremes themselves a and b. Or it is the reciprocal of the arithmetical mean between the reciprocals of the given eXtremes. MEASURE, among Botanists. In describing the parts of plants, Tournefort introduced a geometrical scale, which many of his followers have retained. They measured every part of the plant ; and the essence of the description consisted in an accurate mensuration of the whole. As the parts of plants, however, are liable to variation in no circumstance so much as that of dimension, Linnaeus very rarely admits any other mensu- ration than that arising from the respective length and breadth of the parts compared together. In cases that require actual men- Suration, the same author recommends, in lieu of Tournefort’s ãrtificial scale, the following natural scale of the human body, the Sum of the extremes, and which he thinks is much more conve- nient, and equally accurate. The scale in question consists of 11 degrees, which are as follow : 1. A hair's breadth, or the diameter of a hair (capillus). 2. A line (linea), the breadth of the crescent or white appearance at the root of the finger, (not thumb, mea- Sured from the skin towards the body of the nail ; a line is equal to 12 hairbreadths, and is the 12th part of a Parisian inch. 3. A nail (unguis), the length of a finger nail; cqual to six lines, or half a Parisian inch. 4. A thumb (pollea), the length of the first or outermost joint of the thumb; equal to a Parisian inch. 5. A palm (palmus), the breadth of the palm exclusive of the thumb; equal to three Parisian inches. 6. A span (spithama), the distance between the extremity of the thumb and that of the first finger when extended ; equal to seven Parisian inches. 7. A great span (dodrans), the distance between the extremity of the thumb and that of the little finger when extended, equal to nine inches. 8. A foot (pes), measuring from the elbow to the basis of the thumb; equal to 12 Parisian inches. 9. A cubit (cubitus), from the elbow to the extremity of the middle finger; equal to 17 inches. 10. An arm length (brachium), from the armpit to the extremity of the middle finger, equal to 24 Parisian inches, or two feet. 11. A fathom (orgya), the measure of the human stature ; the distance between the extremity of the two middle fingers, when the arms are extended ; equal, where greatest, to six feet. MEASURE of an Angle, is an arch described from the vertex in any place between its legs. Hence angles are distinguished by the ratio of the arches, described from the vertex between the legs to the peripheries. Angles then are distinguished by those arches; and the arches are distinguished by their ratio to the periphery. Thus an angle is said to be so many degrees as are there in the said arch. MEASURE of a Solid, is a cube whose side is an inch, a foot, or a yard, or any other determinate length. In geometry, it is a cubic perch, divided into cubic feet, digits, &c. ſ MEASURE of Velocity, in Mechanics, is the space passed over by a moving body in a given time. To measure a velocity therefore, the space must be divided into as many equal parts as the time is conceived to be divided into ; the quantity of space answering to such a part of time is the measure of the velocity. - MEASURE of Force for perforating Metal and other Substances. The measure of the force necessary to punch a hole through a plate of metal or other substance, must be an interesting sub- ject to scientific readers. We shall therefore here insert the result of some of Mr. Bevan's experiments made on that sub- ject. A good cylindrical steel punch was made, and fitted to a guide or director, so as to move correctly to a cylindrical hole in a steel plate connected with the guide ; with this instru- ment the artist was able to force cylinders of metal very uni- form, and with little or no bur to the hole, both by simple pressure and by percussion. The results of some experiments made on the force of simple pressure, to make a hole through a metal plate of one-eighth of an inch in thickness, and one-fourth of an inch in diameter, are as follow :—Plate iron, 3900 lbs. ; cast brass, 3200 lbs. ; hammered brass, 3600 lbs. ; copper, M E A M. E. A 631 DIC'TIONARY OF MECHANICAL SCIENCE. * 2800 lbs. The following are the results from the same machine, on specimens of wood, in the direction of the grain, of the same thickness and diameter:—Christiania deal, 135 lbs. ; maho- gany, 170 lbs. ; dry box wood, 356 lbs. ; beech, 204 lbs. ; ash, 197lbs. ; oak 156 lbs. : elm, 122 lbs. MEASURE, in a legal and commercial sense, denotes a certain quantity or proportion of any thing bought, sold, valued, or the like. On the 1st of May, 1825, a total alteration took place in the weights and measures hitherto used in Great Britain. The Rationale of the Imperial System—Take a pendulum which will vibrate seconds in London, on a level of the sea, in a vacuum ; divide all that part thereof which lies between the axis of suspension and the centre of oscillation into 391393 equal parts; then will ten thousand of those parts be an impe- rial inch, twelve whereof make a foot, and thirty-six whereof make a yard. - The Standard Yard is, “that distance between the centres of the two points in the gold studs in the straight brass rod, now in the custody of the clerk of the House of Commons, whereon the words and figures “Standard Yard, 1760,’ are en- graved, which is declared to be the genuine standard of the measure of length called a yard: and as the expansibility of the metal would cause some variation in the length of the rod in different degrees of temperature, the act determines that the brass rod in question shall be of the temperature of 62 deg. Faht. The measure is to be denominated the “Imperial Stan- dard Yard,” and to be the only standard whereby all other measures of lineal extension shall be computed. Thus the foot, the inch, the pole, the furlong, and the mile, shall bear the same proportion to the imperial Standard Yard as they have hitherto borne to the yard measure in general use.” The act also makes provision for the restoration of the stand- ard yard, in case of loss, destruction, or defacement, by a refer- ence to an invariable natural standard, which is to be that pro- portion which the yard bears to the length of a pendulum, vibrating seconds of time in the latitude of London, in a vacuum at the level of the sea; which is found to be as 36 inches (the yard) to 39:1393 (the pendulum); thus a sure means is estab- lished to supply the loss which might by possibility occur. Take a cube of one such inch of distilled water, at 62° of temperature, by Fahrenheit's thermometer, let this be weighed by any weight, and let such weight be divided into 252458 equal parts, then will one thousand of such parts be a troy grain; and seven thousand of those grains will be a pound avoirdu- pois, the operation having been performed in air. Ten pounds such as those mentioned, of distilled water, at 629 of temper- ature, will be a gallon, which gallon will contain two hundred and seventy-seven cubic inches, and two hundred and seventy- four one thousandth parts of another cubic inch. The Standard Pound, is determined to be that standard pound troy weight made in the year 1758, in the custody of the clerk of the House of Commons; such weight is to be denominated the “Imperial Standard Troy Pound;” and after the first of May, 1825, it is to be “the only standard measure of weight from which all other weights shall be derived, computed, and ascertained and that one twelfth part of the said troy pound shall be an ounce, and one twentieth part of such ounce shall be a penny- weight, and that one twenty-fourth part of such penny weight shall be a grain; so that 5760 such grains shall be a pound troy, and 7000 such grains shall be declared to be a pound avoirdupois, and one sixteenth part of the said pound avoirdupois shall be an ounce avoirdupois, and one sixteenth part of such ounce shall be a drachm.” - If the standard pound shall be lost, destroyed, or defaced, the act directs that it shall be recovered by reference to the weight of a cubic inch of water: it having been ascertained that a cubic inch of distilled water, weighed in air by brass weights at the temperature of 62 deg. Fah. and the barometer at 30 inches, is equal to 252.458 grains, and as the standard troy pound contains 5760 such grains, it is therefore established that the original standard pound may be at any time recovered by making another weight to bear the proportion just mentioned to a cubic inch of water. The Standard Gallon is determined by the act to be sucm measure as shall contain ten pounds avoirdupois of distilled Water, weighed in air, at the temperature of 62 deg. Fah, and the barometer at 30 inches, and such measure is declared to be the “Imperial Standard Gallon, and shall be the unit and only standard measure of capacity to be used, as well for wine, beer, ale, spirits, and all sorts of liquids, as for dry goods not measured by heaped measure; and that all other measures shall be taken in parts or multiples of the said imperial standard gallon—the quart being the fourth part of such gallon, and the pint one-eighth part—two such gallons making a peck, eight such gallons a bushel, and eight such bushels a quarter of corn, or other dry goods, not measured by heaped measure. The standard for heaped Measure, for such things as are com- monly sold by heaped measure, such as coal, culm, lime, fish, potatoes, fruit, &c. shall be “ the aforesaid bushel, containing eighty pounds avoirdupois of water, as aforesaid, the same being made round with a plane and even bottom, and being 19% inches from outside to outside ;” and goods thus sold by heaped mea- sure, shall be heaped “in the form of a cone, such cone to be of the height of at least six inches, the outside of the bushel to be the extremity of the base of such cone;” three such bushels shall be a sack, and twelve such sacks shall be a chaldron. Stricken. Measure. The last mentioned goods may be sold either by the heaped measure, or by the standard weight as before mentioned; but all other kind of goods not usually sold by heaped measure, which may be sold or agreed for by mea- sure, the same standard measure shall be used, but it shall not be heaped, but stricken with a round stick, or roller, straight, and of the same diameter from end to end. - N. B. Copies and models of the standard of length, weight, and measure, are to be made and verified under the direction of the Treasury, and every county to be supplied with them for reference whenever required; and after the first of May, 1825, all contracts for sale, &c. by weight or measure shall relate to the standard, unless the contrary is specified. Existing weights and measures may be used, being marked so as to shew the proportion they have to the standard measures and weights. Tables of equalization of the weights to be made by the Treasury. Tables also for the customs and excise, by which the duties will be altered so as to make them equal to what they are at pre- sent, in consequence of the alterations in the weights and mea- sures. See WeIGHTs, &c. • The following extracts from the bill for ascertaining and es- tablishing Uniformity of Weights and Measures, will explain this subject fully :—“Whereas it is necessary, for the security of commerce, and for the good of the community, that weights and measures should be just and uniform : and whereas, not- withstanding it is provided by the Great Charter, that there shall be but one measure and one weight throughout the realm, and, by the treaty of union between England and Scotland, that the same weights and measures should be used throughout Great Britain as were then established in England, yet dif- ferent weights and measures, some larger and some less, are still in use in various places throughout the united kingdom of Great Britain and Ireland, and the true measure of the present standard is not verily known, which is the cause of great con- fusion and of manifest frauds; for the remedy and prevention of those evils for the future, and to the end that certain stand- ards of weights and measures should be established through- out the united kingdom of Great Britain and Ireland : “Be it therefore enacted by the king's most excellent majes- . ty, by and with the consent of the lords spiritual and temporal, . and Commons, in this present parliament assembled, and by the authority of the same, That a cubic inch of distilled water . in a vacuum weighed by brass weights, also in a vacuum at the temperature of sixty-two degrees of Fahrenheit's thermometer, is equal to two hundred and fifty-two grains and seven hundred and twenty-four thousandth parts of a grain, “And be it further enacted, That the standard measure of capacity, as well for liquid as for dry goods not measured by heaped measure, shall be the gallon containing ten pounds avoirdupois weight of distilled water, weighed in air, at the temperature of sixty-two degrees of Fahrenheit's thermometer, the barometer being at thirty inches, to be used as well for wine, beer, ale, spirits, and all sorts of liquids, as for dry goods not measured by heap measure ; and eight such gallons shall be a bushel, and eight such bushels, a quarter of corn or other dry goods not measured by heaped measure. 632 M E A M E A DICTIONARY OF MECHANICAL SCIENCE. * And be it further enacted, That the standard measure of capacity, for coals, culm, lime, fish, potatoes, or fruit, and all other goods and things commonly sold by heaped measure, shall be the aforesaid bushel, containing eighty pounds avoir- dupois of water as aforesaid, the same being made round with a plane and even bottom, and being nineteen inches and a half from outside to outside of such standard measure as aforesaid. “And be it further enacted, That all contracts, bargains, sales, and dealings, which shall be made or had within any part of the united kingdom of Great Britain and Ireland, for any work to be dome, or for any goods, wares, merchandise, or other thing to be sold, delivered, done, or agreed for, by weight or measure, where no special agreement shall be made to the contrary, shall be deemed, taken, and construed to be made and had according to the weights and standard measures ascertain- ed by this act; and in all cases where any special agreement shall be made, with reference to any weight or measure estab- | lished by local custom, the ratio or proportion which every such local weight or measure shall bear to any of the said standard weights or measures, shall be expressly declared and specified in such agreement, or otherwise such agreement shall be null and void. - - “And whereas it is expedient that persons should be allowed to use the several weights and measures which they may have in their possession, although such weights and measures may not be in conformity with the standard weights and measures established by this act; be it therefore enacted, That it shall and may be lawful for any person or persons to buy and sell goods and merchandise by any weights or measures established either by local custom, or founded on special agreement; pro- vided always, that in order that the ratio or proportion which all such measures and weights shall bear to the standard weights and measures established by this act, shall be and be- come a matter of common notoriety, the ratio or proportion which all such customary measures and weights shall bear to the said standard weights and measures, shall be painted or marked upon all such customary weights and measures re- spectively; and that nothing herein contained shall extend, or be construed to extend, to permit any maker of weights or measures, or any person or persons whomsoever, to make any weight or measure at any time after, except in conformity with the standard weights and measures established under the provisions of this act. “And be it further enacted, That accurate tables shall be prepared and published, shewing the proportions between the weights and measures heretofore in use, as mentioned in such inquisitions, and the weights and measures hereby established; and after the publication of such tables, all future payments to be made shall be regulated according to such tables. “And whereas the weights and measures by which the rates and duties of the customs and excise, and other his majesty’s revenue, have been heretofore collected, are different from the weights and measures of the same denominations directed by this act to be universally used; and whereas the alteration of such weights and measures may, without due care had therein, greatly affect his majesty's revenue, and tend to the diminish- ing of the same ; for the prevention thereof, be it therefore enacted, That, so soon as conveniently may be, accurate tables shall be prepared and published; in order that the several rates and duties of customs and excise, and other his majes- ty’s revenue, may be adjusted and made payable according to the respective quantities of the legal standards directed by this act to be universally used; and that from and after the publi- cation of such tables, the several rates and duties thereafter to be collected by any of the officers of his majesty’s customs or excise, or other his majesty's revenue, shall be collected and taken according to the calculations in the tables to be prepared as aforesaid.” TABLE of the several Standard Measures.—ENGLISH. Barleycorns Long Measure. 3 - 1 Inch 36 - 12 – 1 Foot 108 - 36 - 3 = 1 Yard 594 – 198 = 16}= 53- 1 Pole 23760 = 7920 = 660 = 220 = 40 = 1 Furlong 1900so = 63366 = 5250 E 1760 = 320 = 8 – Niile, Also, - 4 Inches............ = 1 Hand 6 Feet . . . . . . . . . . . . . = 1 Fathom. 3 Miles . . . . . . . . . . . . = 1 League. 60 Geographical Miles = 1 Degree. 694 English Miles 1 Degree nearly. 360 Degrees, or 25000 Miles, is equal to the Circumference of the Earth nearly. Cloth. Measure. Inches 2} = 1 Nail 9 – 4 = 1 Quarter. 36 - 16 = 4 – 1 Yard. 27 – 12 - 3 = 1 Ell Flemish. 45 – 20 – 5 = 1 Ell English. 54 - 24 – 6 = 1 Ell French. The French standard was formerly the aune or ell, containing 3 Paris feet, 7 inches, 3 lines, or 1 yard 2-sevenths English ; the Paris foot royal exceeding the English by 68-thousandth parts. This ell is divided two ways, viz. into halves, thirds, sixths, and twelfths; and into quarters, half-quarters, and sixteenths. The standard in Holland, Flanders, Sweden, a good part of Germany, many of which were formerly called the Hans- towns, as Dantzic and Hamburgh, and at Geneva, Frankfort, &c. is likewise the ell; but the ell in all these places differs from the Paris ell. In Holland it contains one Paris foot eleven lines, or four-sevenths of the Paris ell. The Flanders ell contains two feet, one inch, five lines, and half a line, or seven-twelfths of the Paris ell. The ell of Germany, Brabant, &c. is equal to that of Flanders. - The Italian measure is the branchio, brace, or fathom. This obtains in the states of Modena, Venice, Florence, Lucca, Milan, Mantua, Bologna, &c., but is of different lengths. At Venice it contains one Paris foot eleven inches three lines, or eight-fifteenths of the Paris ell. At Bologna, Modena, and Mantua, the brace is the same as at Venice. At Lucca it con- tains one Paris foot nine inches ten lines, or half a Paris ell. At Florence, it contains one foot nine inches four lines, or forty-nine hundredths of a Paris ell. At Milan, the brace for measuring of silks is one Paris foot seven inches four lines, or four-ninths of a Paris ell: that for woollen cloths is the same with the ell of Holland. Lastly, at Bergama, the brace is one foot seven inches six lines, or five-ninths of a Paris ell. The usual measure at Naples, however, is the canna, containing six feet ten inches and two lines, or one Paris ell and fifteen- seventeenths. e The Spanish measure is the vara or yard, in some places called the bara, containing seventeen twenty-fourths of the Parisell. But the measure in Castile and Valencia is the pan, span, or palm ; which is used, together with the canna, at Genoa. In Arragon, the vara is equal to a Paris ell and a half, or five feet five inches six lines. º The Portuguese measure is the cavedos, containing two feet eleven lines, or four-sevenths of a Paris ell ; and the Vara, an hundred and six whereof make an hundred Paris ells. The Piedmontese measure is the ras, containing one Paris foot nine inches ten lines, or half a Paris ell. In Sicily, their measure is the canna, the same with that of Naples. e The Muscovy measures are the cubit, equal to one Paris foot four inches two lines; and the arcin, two whereof are equal to three cubits. º * - The Turkish and Levant measures are the picq, containing two feet two inches and two lines, or three-fifths of the Paris ell. The Chinese measure, the cobre, ten whereof are equal to three Paris ells. In Persia, and some parts of the Indies, the gueze, whereof there are two kinds; the royal gueze, called also the gueze monkelser, containing two Paris feet ten inches eleven lines, or four-fifths of the Paris ell; and the shorter gueze, called simply gueze, only two-third; of the former. At §oa and Ormuz, the measure is the vara, the same with that of the Portuguese, having been introduced by them. In Pegu, and some other parts of the Indies, the cando or candi, equal to the eli of Venice. At Goa, and other parts, they use a larger cando, equal to seventeen Dutchells; exceeding that of Babel ºre 1. Zºe 633. ME ("H.I.N. 11.1L POWERs. P U L L E Y' s Aº. 10. Connnnon Balance. * 27 p - - º - - - - Wº%. A º C. False Balance. Thread of the Screw. * /*. Zºº /? - = - - 5 - - - -- - - - - - - - - - - y Aºz. B A. Fº. 20 C - B E. F. | Inclined Planes. º … A. L. E v. E. R. - Zºo /7. A d C - Affinity of the Inclined Plane to the screw. º Endless ºr Zºº Screw. | | -º | | || | . | *|| - | - - | º - º | - - |Zºº - Lº- - º nº lº -n. L-lºº. M E A M E A DICTIONARY OF MECHANICAL SCIENCE, land in Scotland is 23 ells, or 74 feet. and Balsora by ºper cent, and the vara by 6}. In Siam, they tº & The ken use the ken, short of three Paris feet by one inch. contains two soks, the sok two keubs, the keub twelve nious or inches, the niou to be equal to eight grains of rice, i. e. to about || nine lines. At Camboia, they use the haster; in Japan, the tatam; and the span on some of the coasts of Guinea, , , Square Measure. - '. Inches. . . . . . 144 = 1 Foot. 1296 = 9 = . 1 Yard. 39204 = 2723 = .363 = 1. Pole. 1568160 = 10890 – 1210 = 40 + 1 Rood, - 6272640 = 43560 = 4840 = 160 = 4 = 1 Acre, Also, 5, Yards = 1 Pole. 40 Poles 1 Rood. 4 Roods = 1 Acre. Square, Superficial, or Land Measure-English square mea- sures are raised from the yard of 36 inches multiplied into itself, and thus producing 1296 square inches in the square yard; the divisions of this are square feet and inches; and the multiples, poles, roods, and acres. Because the length of a pole is 53 yards, the square of the same contains 30+ square yards. A square mile contains 640 square acres. In measur- ing fens and woodlands, 18 feet are generally allowed to the pole, and 21 feet in forest land. A hide of land, frequently mentioned in the earlier part of the English history, contained about 100 arable acres; and five hides were esteemed a knight's fee. At the time of the Norman conquest, there were 243,600 hides in England. - - s “ Scotch square or land measure is regulated by the Scotch ell: 36 square ells = 1 fall, 40 falls = 1 rood, 4 roods = acre. The proportion between the Scotch and English acre, supposing the feet in both measures alike, is as 1369 to 1089, or nearly as 5 to 4. If the difference of the feet be regarded, the proportion is as 10,000 to 7869. The length of the chain for measuring A husband-land con- tains six aeres of sock and scythe land, that is, of land that may be tilled with a plough or mown with a scythe ; 13 acres of arable land make one ox-gang; and four ox-gangs make a poundland of old extent. * French square measures are regulated by 12 square lines in the inch square, 12 inches in the foot, 22 feet in the perch, and 100 perches in the arpent or acre. - Cubic Measure. Inches. 1728 – 1 Foot. 46656 – 27 = 1 Yard. . Wine Measure, Pints. - 2 - 1 Quart. - 8 – 4 = 1 = 1 Gallon = 231 Cubic Inches. 336 – 168 – 42 – 1 Tierce. 504 – 252 = 63 = 1} = 1 Hogshead. 672 E 336 – 84 E 2 = 1% = 1 Puncheon. 1008 = 504 = 126 = 3 = 2 = 1 = 1 Pipe. 2016 – 1008 = 252 = 6 = 4 = 3 = 2 = 1 Tun 231 Cubic Inches = 1 Gallon. 10 Gallons = 1 Anker 18 Ankers = 1 Runlet 31} Gallons = 1 Barrel . Ale and Beer Measure. Pints. - - 2 = . 1 Quart. , 8 = , 4 = 1 Gallon, 72 = 36 = 9 = 1 Firkin. 144 = 72 – 18 = 2 = 1 Barrel 288 – 144 c 36 = 4 = 2 = 1 Barrel. 432 = 216 = 54 = 6 = 3 = 13 = 1 Hogshead. 576 = 288 = .72 = 8 = 4 = 2 = 1% = 1 Puncheon. 864 = 432 = 108 = 12 = 6 = 3 = 2 = 1% = 1 Butt. The Ale Gallon contains 282 Cubic Inches. º is 32 gallons, and the barrel for beer 36 gallons. to be 34 gallons. 65. ScoreH,-Long Measure.’ ‘’’ ‘’’. . . . . Eng. Inches. . . .”. - & An ºil................ - 37.2 A Fall . . . . . . . . . . . . . . . . E .223-2 A Furlong . . . . . . . . . . . . = 8928 - A Mile . . .............. = 71424. A Link ................. = 8-928 A Chain, or Short Rood = 89.28. A Long Rood - 1339.2 Measure of Capacity. - Eng. Cub. Inch. A Gill - 6°462 A Mutchkir, – 25'85 A Choppin = 51.7 A Pint = 103-4 A Quart = 206.8 A Gallon – 827-23 A Hogshead = 13235-7, or 16 Gallons. Cubical Measures, or Measures of Capacity, for Liquids.—The English measures were originally raised from troy weight: it being enacted by several statutes, that eight pounds troy of wheat, gathered from the middle of the ear, and well dried, should weigh a gallon of wine measure, the divisions and mul. tiples whereof were to form the other measures; at the same time it was also ordered, that there should be but one liquid measure in the kingdom; yet custom has prevailed, and there having been introduced a new weight, viz. the avoirdupois. we have now a second standard gallon adjusted thereto, and therefore exceeding the former in the proportion of the avoir- dupois weight to troy weight. From this latter standard are raised two several measures, the one for ale, the other for beer The sealed gallon at Guildhall, which is the standard for wines, spirits, oils, &c. was supposed to contain 231 cubic inches; and on this supposition the other measures raised therefrom will contain as in the foregoing table ; yet by actual experiment, made in 1688, before the lord mayor and the commissioners of excise, this gallon was found to contain only 224 cubic inches; it was, however, agreed to continue the common supposed contents of 231 cubic inches; so that all computations stood on their own footing. Hence, as 12 is to 231, so is 14% to 281}, the cubic inches in the ale gallon; but in effect the ale quart contained 70} cubic inches, on which principle the ale and beer gallon will be 282 cubic inches. The several divisions and multiples of these measures, and their proportions, are ex- hibited in the foregoing tables. The barrel for ale in London In all other places of England, the barrel, both for ale and beer, was wont Scotch liquid measure is founded on the pint. The Scotch pint was formerly regulated by a standard jug of cast metal, the custody of which was committed to the borough of Stirling. This jug was supposed to contain 105 cubic inches; and though, after several careful trials, it has been found to contain only about 103% inches; yet, in compliance with established custom, founded on that opinion, the pint stoups are still regu- lated to contain 105 inches, and the customary ale measures are about , above that standard. It was enacted by James I. of Scotland, that the pint should contain 41 ounces trone weight of the clear water of Tay, and by James VI. that it should contain 55 Scots troy ounces of the clear water of Leith. This affords another method of regulating the pint, and also ascertaining the ancient standard of the trone weight. As the water of Tay and Leith is alike, the trone weight must have been to the Scots troy weight as 55 to 41, and therefore the pound trone must have contained about 213 ounces Scots troy. - gº . . 1 mutchkin. 1 quart. 4 gills — 2 pints = 1 . 2 mutchkins = 1 chopin. 4 quarts E 1 gallon. 2 chopins E 1 pint. The Scotch, quart contains 210 inclies, and is, therefore about ſº less than the English wine gallon, and about # less than the ale gallon. As to the liquid measures of foreign nations, it is to be 7 Y 634 Aſ E A M E. A. DICTIONARY OF MECHANICAL SCIENCE. observed, that their several vessels for wine, vinegar, &c. have also various denominations, according to their different sizes and the places wherein they are used. The woeders of Ger- many, for holding Rhenish and Moselle wines, are different in their gauges; some containing 14 aumes of Amsterdam mea- sure, and others more or less. The aume is reckoned at Amsterdam for 8 steckans, or 20 verges, or for 3 of a tun of 2 pipes, or 4 barrels, of French or Bourdeaux, which at this latter place is called tiergon, because three of them make a pipe or two barrels, and six the said tun. The steckan is 16 mingles, or 32 pints; and the verge is, in respect of the said Rhenish and Moselle, and some other sorts of wine, 6 mingles; but in measuring brandy it consists of 6 mingles. The aume is divided into 4 anckers, and the ancker into 2 steckans, or 32 mingles. The ancker is taken sometimes for h of a tun, or 4 barrels; on which footing the Bourdeaux barrel ought to contain at Amsterdam (when the cask is made aceording to the just gauge) 12% steckans, or 200 mingles, wine and lees ; or 12 steckans, or 192 mingles, racked wine; so that the Bour- deaux tun of wine contains 50 steckans, or 800 mingles, wine and lees; and 48 steckans, or 768 mingles, of pure wine. The barrels or poinçons of Nantes, and other places on the river Loire, contain only 12 steckans, Amsterdam measure. The wine tun of Rochelle, Cogniac, Charente, and the isle of Rhé, differs very little from the tun of Bourdeaux, and consequently from the barrels and pipes. . A tun of wine of Chalosse, Bay- onne, and the neighbouring places, is reckoned 60 steckans, and the barrel 15, Amsterdam measure. -- The old muid of Paris contains 150 quarts or 300 pints, wine and lees; or 280 pints clear wine; of which muids three make a tun. . * The butts or pipes from Cadiz, Malaga, Alicant, Benecarlo, Saloe, and Mataro, and from the Canaries, Lisbon, Oporto, and Fayal, are very different in their gauges, though in affreightments they are all reckoned two to the tun. Vinegar is measured in the same manner as wine, but the measures for brandies are different; these spirits from France, Spain, Portugal, &c. are generally shipped in large casks called pipes, butts, and pieces, according to the places from whence they are imported, &c. In France, brandy is shipped in casks called pieces at Bourdeaux, and pipes at Rochelle Cogniac, the isle of Rhé, and other neighbouring places, which contain some more and some less, even from 60 to 90 Amster- dam verges or veertels, according to the capacity of the ves- sels, and the places they come from. Dry Measure. Pints. 8 = 1 Gallon. 16 = 2 = 1 Peck. . 64 = ′ 8 = 4 = 1 Bushel. 256 = 32 = 16 = 4 – 1 Coomb. 512 = 64 = 32 = 8 = 2 = 1 Quarter. 2560 = 320 = 160 = 40 = 10 = 5 = 1 Wey. 5120 = 640 = 320 = 80 = 20 = 10 = 2 = 1 Last. 2684 Cubic Inches = 1 Gallon. 36 ‘Bushels = 1 Chaldron of Coals. Measure of Capacity for things Dry, was the Winehester gal- lon heretofore ; as for corn, salt, coals, and other dry goods, in England. The gallon contains 2724 cubic inches. The bushel 8 gallons, or 2178 inches. A cylindrical vessel, 18% inch. diameter, and 8 inch, deep, is appointed to be used as a bushel in levying the malt tax. A vessel of these dimensions is rather less than the Winchester bushel of 8 gallons, for it contains only 2150 inches, though probably there was no difference intended. The denominations of dry measure commonly used, are given in the first of the subjoined tables. Four quarters of corn make a chaldron, five quarters make a wey or load, and 10 quarters make a ton. In measuring sea coal, five pecks make a bushel, nine bushels make a quarter or vatt, four quarters make a chaldron, and 21 chaldrons make a score. 40 feet hewn timber make a load. 50 feet unhewn timber make a load. 32 gallons make a herring barrel. 42 gallons make a salmon barrel. . . 1 cwt. gunpowder makes a barrel. 256 lbs. soap make a barrel. - 10 dozen candles make a barrel. 12 barrels make a last. - Scotch dry measure. There was formerly only one measure of capacity in Scotland; and some commodities were heaped, others straiked, or measured exactly to the capacity of the standard. The method of heaping was afterwards forbidden as unequal, and a larger measure appointed for such commo- dities as that custom had been extended to. The wheat firlot, used also for rye, pease, beans, salt, and grass seeds, contains 21 pints 1 mutchkin, measured by the Stirling jug. ... The barley firlot, used also for oats, fruit, and potatoes, contains 31 pints. A different method of regulating the firlot was appointed from the dimensions of a cylindrical vessel. The diameter for both measures was fixed at 19, inches, the depth 73 inches for the wheat firlot, and 13% for the barley firlot. A standard con- structed by these measures is rather less than when regulated by the pint; and as it is difficult to make vessels exactly, cylin- drical, the regulation by the pint has prevailed, and the other method gone into disuse. : . If the Stirling jug contains 103} inches, the wheat firlot will contain 2109 inches, which is more than two per cent. larger than the legal malt bushel of England, and about one per cent. larger than the Winchester bushel; and the barley firlot will contain 3208 inches. The barley boll is nearly equal to six legal malt bushels. In Stirlingshire, 17 pecks are reckoned to the boll; in Inverness-shire, 18 pecks; in Ayrshire, the boll is the same as the English quarter. And the firlots in many places are larger than the Linlithgow standard. French dry, are, the litron, bushel, minot, mine, septier, mauid, and tun. The litron is divided into two demilitrons, and . four quarter litrons, and contains 36 cubic inches of Paris. By ordonnance, the litron is to be three inches and a half high, and three inches 10 lines broad. The litron for salt is larger, and is divided into two halves, four quarters, eight demi- quarters, and 16 mesurettes. The French bushel is different in different jurisdictions. At Paris it is divided into demi- bushels, each demibushel into two quarts, the quart into two half-quarts, and the half-quart into two litrons, so that the bushel contains 16 litrons. By ordonnance the Paris bushel is to be eight inches two lines and a half high, and ten inches broad, or in diameter within-side. The minot consists of three bushels, the mine of two minots or six bushels, the septier of two mines or 12 bushels, and the muid of 12 septiers or 144 bushels. The bushel of oats is estimated double that of any other grain; so that there go 24 bushels to make the septier, and 288 to make the muid. It is divided into four picotins, the picotin containing two quarts, or four litrons. The bushel for salt is divided into two half bushels, four quarters, eight half-quarters, and 16 litrons; four bushels make a minot, 16 a septier, and 192 a muid. The bushel for wood is divided into halves, quarters, and half quarters. Eight bushels make the • ** minot, 16 a mine; 20 mines, or 320 bushels, the muid. For plaster, 12 bushels make a sack, and 36 sacks a muid. For lime, three bushels make a minot, and 48 minots a muid. The minot is by ordonnance to be 11 inches 9 lines high, and 14 inches 8 lines in diameter. The minot is composed of three bushels, or 16 litrons; four minots make a septier, and 48 a muid. The French mine is no real vessel, but an estimation of several others. At Paris the mine contains six bushels, and 24 make the muid ; at Rouen the mine is four bushels; and at Dieppe 18 mines makes a Paris muid. The septier differs in different places: at Paris it contains two mines, or eight bushels, and 12 septiers the muid. At Rouen the septier con- tains two mines or 12 bushels. Twelve septiers make a muid at Rouen as well as at Paris; but 12 of the latter are equal to 14 of the former. At Toulon the septier contains a mine and a half; three of which mines make the septier of Paris. The muid or muy of Paris consists of 12 septiers, and is divided into mines, minots, bushels, &c. That for oats is double that for other grain, i.e. contains twice the number of bushels. At Orleans the muid is divided into mines, but those mines only contain two Paris septiers and a half. In some places they M E A M. r A 635 DICTIONARY OF MECHANICAL SCIENCE. use the tun in lieu of the muid, particularly at Nantes, where | it contains 10 septiers of 16 bushels each, and weighs between 2200 and 2250 pounds. Three of these tuns make 28 Paris septiers. At Rochelle, &c. the tun contains 42 bushels, and weighs two per cent. less than that of Nantes. At Brest it contains 20 bushels, is equal to 10 Paris septiers, and weighs about 2240 pounds. See TUN. - Dutch, Swedish, Polish, Prussian, and Muscovite. In these places, they estimate their dry things on the foot of the last, lest, leth, or lecht; so called according to the various pronun- ciations of the people who use it. In Holland, the last is equal to 19 Paris septiers, or 38 Bourdeaux bushels, and weighs about 4560 pounds; the last they divide into 27 muids, and the muid into four scheples. In Poland, the last is 40 Bourdeaux bushels, and weighs about 4800 Paris pounds. In Prussia, the last is 133 Paris septiers. In Sweden and Muscovy they measure by the great and little last; the first containing 12 barrels, and the second half as many. In Muscovy, they likewise use the chefford, which is different in various places; that of Archangel is equal to three Rouen bushels. - - Italian. At Venice, Leghorn, and Lucca, they estimate their dry things on the foot of the staro or staio; the staro of Leg- horn weighs 54 pounds; 112 staros and seven-eighths are equal to the Amsterdam last. At Lucca, 119 staros make the last of Amsterdam. The Venetian staro weighs 128 Paris pounds; the staro is divided into four quarters. Thirty-five staros and one-fifth, or 140 quarters and four-fifths, make the last of Amsterdam. At Naples and other parts, they use the tomolo or tomalo, equal to one-third of the Paris septier. Thirty-six tomoli and a half make the carro, and a carro and a half, or 54 tomoli, make the last of Amsterdam. At Palermo, 16 tomoli make the salma, and four mondili the tomolo. Ten salmas and three-sevenths, or 171 tomoli and three-sevenths, make the last of Amsterdam. - Flemish. At Antwerp, &c. they measure by the viertel ; 32 and one-half whereof make 19 Paris septiers. At Ham- burgh, the schepel; 90 whereof make 19 Paris sepfiers. Spanish and Portuguese. At Cadiz, Bilboa, and St. Sebas- tian, they use the famega; 23 whereof made the Nantes or Rochelle tun, or nine Paris septiers and a half; though the Bilboa fanega is somewhat larger, insomuch that 21 fanegas make a Nantes tun. At Seville, &c. they use the anagoras, containing a little more than the Paris mine; 36 anagoras make 19 Paris septiers. At Bayonne, &c. the concha; 30 whereof are equal to nine Paris septiers and a half. At Lisbon, the alquiver, a very small measure, 240 whereof make 19 Paris septiers, 60 the Lisbon muid. - TABLE of the several Standard Measures.—FRENch. - Old System. - A Point . . . . . . . . . . . . . . . . . .0148025 English Inches. A Line. . . . . . . . . . . . . . . . . . •0888.15 An Inch. . . . . . . . . . . . . . . . . 1.06578 A Foot . . . . . . . . . . . . . . . . 12”78933. {-ºmsºmº uºmº An Ell . . . . . . . . . . . . . . . . . . 44 French Inches. A Sonde. . . . . . . . . tº e e o 'º º º 5 French Feet. A Toise wº- - 6 A Perch *me 18 A Perch Royal — 22 - A League . . . . . . . . . . . . . . . 2282 Toises. A Square Inch . . . . . . . . . . 1-13582 English Inches. An Arpent . . . . . . . . . . . . . . # English Acre. Arpent Royal............ 1% A Cubic Inch ....... . . . . . 121063 English Cub. Inch. A Litron. . . . . . . . . . . . . . . . 65°34 A Boisseau .............. 16 Litrons. A Minot . . . . . . . . . . . . . . . . . 3 Boisseaux. A Mine . . . . . . . . . . . . . . . . 2 Minots. A Septier . . . . . . . . . . . . . . . 2 Mines. A Muid. . . . . . . . . . . . © e º tº e 12 Septiers. Metre Measure.—Superficial Measure. Eng. Yards. Are, a Square Decametre . . . . . . . . . . . . . . 119:6046 Decare. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1196.046 . - Hecatare . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11960°46 Millilitre ...... . . . . . Lineal Measure. Eng. Inches. r Eng. Inches. Millimetre . • . . . . . . . e 0-3937 | Decametre .......... 393-71 Centimetre * * * * : * c e º e “39371 | Hecametre . . . . . . . . . . .3937-1 Decimetre........ 3-9371. Chiliometre .... . . . . . .39371° Metre. . . . . . . . . . . . . . 39°371 || Myriometre ......... 393710" * * * * * * Measure of Capacity. Eng. Cab. Inc. Eng. Cub. Inc. tº - º '06103 || Decalitre ........... 610:28 Centilitre C & e º 'º - - G - e a *61028 | Hecatolitre . . . . . . . . . 6102.8 Decilitre. e e º º º • . . . . . 6-1028 Chiliolitre ........... 61028 Litre . . . . . . . . . . . . . . 61-028 Myriolitre .......... 610280: Solid Measure. . Eng. Cub. Feet. Decisire, for fire wood .................... 3’5317 Stere, a Cubic Metre. . . . . . . . . . . . . . . . . . . . . .35°317 Decastere ......... e e º G & ºl e e s e e s • - - - - - - - - - 353°17 It will be observed, that, in this system it is 'only necessary to remember the metre, are, litre, and stere, all the others having certain relations to these, being equal to them taken 10, 100, 1000, &c. times, or divided by those numbers; and these are indicated in all cases by the preceding part of the word, the terminations in all being the same ; that is, in each class of measures. Thus, - - Deca prefixed, denotes 10 times; heca, 100 times; chilio, 1000 times; &c. On the other hand, deci, centi, milli, denotes the 10th part, 100th part, 1000th part, &c. So that metre is the element of long measures; are, of superficial measures; stere, that of solid measure ; and litre, is the element of the measures of capacity; also, gramme is the element of all weights, being itself the weights of a cubic centimetre of distilled water.—The are is the square decametre. The litre, the cubie decimetre. The stere, the cubic metre. The metre itself, one ten-millionth part of the terrestrial arc intercepted between the equator and north pole, as determined by the actual measurement of degrees in different latitudes. .' - - One need only cast an eye over this system of measures, to see at once the great advantages that it posseses over the com- plicated systems of any other country. It not only renders the system incomparably more simple for all the practical purposes of life, but it annihilates at once all those rules in arithmetic, classed under the terms compound addition, subtraction, multi- plication, and division ; reducing the whole of arithmetic to the first simple rules. A child, under this system of weights and measures, may learn every thing necessary for entering into the common concerns of the world in a month, as well and | better than in a year under our complicated system. It is per- haps too much to expect that we shall ever forego our preju- dices so far as to adopt this system of a rival nation. Yet it must be allowed to be of infinite importance to reduce all those in- congruous and incomparable measures now in use, to one sim- ple and uniform system, that should be understood by every one; and we should therefore be happy to find the subject taken up by the English parliament, being well worthy of its serious attention. Table of the Proportion of Long Measures of different Nations to the English Foot; which, for the sake of comparison, is supposed to be divided into 1000 parts. - English foot ... . . . . . . . . . . . . º e º a e s ſº a o 1000 Paris. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... 1068 Venetian . . . . . . . • • . . . . . . . . . . . . . . . . . . . I 162 Rhinland . . . . . . . . . . . . . e e s e s a s • * * * * * * 1033 Strasburgh . . . . . . . . . . . . . . . . . . . . . . ... 951 Noremberg . . . . . . . . . . . . . . . . ... . . . . . . 1000 Dantzic . . . . . . . . & a tº e º e º is a e . . . . . . . . . . 944 Danish . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1042 Swedish. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 977; M E. G. M E C Diction ARY OF MECHANICAL SCIENCE. Different Itinerary Measures. A French league is about .. 2; English miles A German mile. . . . . . . . . 4 Ditto. . . A Dutch mile .......... 33 Ditto. An Italian mile . . . . . . . . ; Ditto. . . ÁSpanish league....... 33 Ditto. A Russian verst........ # Ditto. Standard of MeAsuke. Various attempts have been made by different mathematicians to find a perpetual standard of measure, which might be referred to at any time and under any circumstance, supposing the standard in present use to be lost. The above-metric system of the French is founded on this prin- ciple; the terrestrial arc, from the equator to the pole, being taken as thé standard of universal comparison. MEASURE, in Geometry, denotes any quantity assumed as one or unity, to which the ratio of the other homogeneous or similar quantities is expressed. - - Measure of Wood for Firing, is usually the cord, four feet high, as many broad, and eight long ; this is divided into two half cords, called the ways, and by the French mémbrwres from the pieces stuck upright to bound them; or voyes, as being supposed half a waggon load. MEASURE for Horses, is the hand, which by statute contains . four inches. MEAT, THE PReservation. The Moors have an easy method of preparing flesh-meat, without spices, and very little salt, to keep it good, and always ready for eating, for two or three years in the warmest climates. F. The meat thus prepared is called elcholle, and is made of beef, mutton, or camel's flesh, but chiefly of becf. It is first uniformly cut in long slices, well salted, and suffered to lie twenty-four hours in the pickle. It is then removed from those tubs into others filled with fresh water, where it remains for a night; it is next taken out, and hung on cords in the sun to dry. . When thoroughly dry and hard, it is cut into pieces three inches long, and thrown into a pan or cauldron of boiling oil and suet sufficient to cover it; thus it is boiled, till it be very clear and red on cutting it, when it is again taken out, and set to drain. After having undergone this process, it stands to cool, while jars are pre- pared for storing it ; at the same time pouring upon it, the liquid in which it was boiled or fried ; and as soon as it is thoroughly cold, the vessels are closely stopped. Preserved in this manner, it will remain hard, and keep good for two years; the hardest is considered the best and most palatable. Thus it is brought to the table by the Moors, after having been stewed or fried, seasoned either with garlic, or the juice of lemon, and is considered an excellent dish. Meat is also pre- served by the pyroligneous acid. See Aci D. º - MECHANICAL, an epithet applied to whatever relates to mechanics: Thus we say, mechanical powers, causes, &c. The mechanical philosophy is the same with what is otherwise called corpuscular philosophy, which explaims the phenomena of nature, and the operations of corporeal things, on the principles of mechanics; viz. the motion, gravity, arrangement, disposition, greatness or smallness, of the parts which compose natural bodies. This manner of reasoning is much used in medicine; and, according to Dr. Quincy, is the result of a thorough acquaintance with the structure of animal bodies: for con- sidering an animal body as a composition out of the same mat- ter from which all other bodies are formed, and to have all those properties which concern a physician's regard, only by virtue of its peculiar construction; it naturally leads a person to consider the several parts, according to their figure, con- texture, and use, either as wheels, pulleys, wedges, levers, screws, cords, canals, strainers, &c. For which purpose, con- tinues he, it is frequently found helpful to design in diagrams, whatsoever of that kind is under consideration, as is customary in geometrical demonstrations. . . . . . MechANICAL, in Mathematics, denotes a construction of some problem, by the assistance of instruments, as the dupli- cature of the cube and quadrature of the circle, in contradis- tinction to that which is done in an accurate and geometrical IAaldū GIſ. * * • . . . * * - MECHANICAL; Curve, is a curve, according to Descartes, which cannot be defined by any algebraic equation; and so: WA - stands contradistinguished from algebraic or geometrical curves. . Leibnitz and others call these mechanical curves transcendental, and dissent from Descartes, in excluding them out of geometry. Leibnitz found a new kind of transcendental equations, where these curves are defined: but they do not continue constantly the same in all points of the curve, as algebraic ones do. . See TRANSCENDENTAL, - MechAN1cAL Solution of a Problem, is either when the thing is done by repeated trials, or when limes used in the solution are not only truly geometrical, or by organical construction. MECHANICS, that branch of practical mathematics, which considers motion and moving powers, their nature and laws, with their effect in machines. See MACHINE. The term is equally applied to the doctrine of equilibrium of powers, more properly called statics, and to that science which treats of the generation and communication of motions, which constitutes dynamics, or mechanics strictly so called. This science is divided by Newton into practical and rational mechanics, the former of which relates to the mechanical powers; viz., the lever, balance, wheel and axis, pulley, wedge, screw, inclined plane, and funicular machine: and the latter, or rational me- chanics, to the theory of motion; shewing when the forces or powers are given, how to determine the motion that will result from them; and conversely, when the circumstances of the motion are given, how to trace the forces or powers from which they arise. Leslie, in his course of natural philosophy, incor- porates mechanics with those other branches of natural science which unfold the general principles that connect the events of the material world. The science of mechanics having thence for its object the consideration of machines, their elements, principles of action, and methods of operation, we may divide them into two classes—those that are general, and such as are particular: To the former belong the concentrator of force, and the engine of oblique action, which, when composed of connected cords, has been named the funicular machine;—to the latter belong the lever, the wheel and axle, the inclined plane and screw, the wedge, and the pulley, commonly called the simple mechanical powers. - Mechanics, according to the ancient sense of the word, con- siders only the energy of organa, or machines. The authors who have treated the subject of mechanics systematically, have observed, that all machines derive their efficacy from a few simple forms and dispositions that may be given to the organa, | which are interposed between the agent and the resistance to be overcome; and to those simple forms they have given the name of mechanical powers, simple powers, or simple machines. The practical uses of the several mechanical powers were un- doubtedly known to the ancients, but they were almost wholly unacquainted with the theoretical principles of this science till a very late period; and it is, therefore, not a little surprising that the construction of machines, or the instruments of me- chanics, should have been pursued with such industry, and carried by them to such perfection. Vitruvius, in his tenth book, enumerates several ingenious machines, which had then been in use from time immemoral. We find, that for raising or transporting heavy bodies, they employed most of the means which are at present commonly used for that purpose, such as the crane, the inclined plane, the pulley, &c.; but with the theory or true principles of equilibrium they seem to have been unacquainted till the time of Archimedes. . When, how- ever, we consider the vast gigantic undertakings of the ancients, we cannot help believing that their genius supplied them with many engines of which we now know nothing; though we far sur- pass them in numerous methods of abridging human labour and the application of force. Yet from the time of Archimedes tili the sixteenth century, the theory of mechanics remained as that prince of science left it. : Stevenus a Fleming, Galileo, Torricelli, Descartes, Huygens, Wallis, Wren, Newton, Leib- nitz, Dechales, Oughtred, Keil, Delahire, Lagrange, Atwood, Prony, Emerson, Watt, Gregory, Young, &c. have, in succes- sion, since the period to which we have alluded, explained and applied the principles of this civilizing science in a wonderful manner. * - d The Lever, which consists of an inflexible bar A B C, (see the Plate, fig. 20,) either straight or bent, resting on a point C, called the fulcrum, the power being applied at the end A of M E C M E C DICTIONARY OF MECHANICAL SCIENCE, the arm A C, to raise a weight at the end B of the other arm C B. Throwing out of view the weight of the lever itself, and supposing it to be at first horizontal; let it shift into the proxi- | mate position A/C B'. The minute arcs A A' and B B thus described may be regarded as tangents, and, consequently, while the power P descends vertically through the space A.A.', the weight W rises through the space B B'; wherefore the opposite momenta being equal, P × A A' = W × B B', and | P : W : : B B : A A' : : B C : A C, or the power and weight are inversely as their distance from the fulcrum. Levers are usually distinguished into three kinds, according to the rela- tive position of the power, the weight, and the fulcrum. 1. When the fulcrum D, (fig. 1,) lies between the power P and the weight W. . This kind includes the crow and handspike, pincers, and scissars. The toothed hammer is only a bent lever of this kind. Its invention was in mythology ascribed to Neptune, his trident being only a three-pronged crow. The arm B C is commonly longer than A B, and consequently the weight W exceeds the power P. The number of times which the weight contains the power, is always called the mechanical advantage or purchase. In making experiments with this machine, the shorter arm AB must be as much thicker than the longer arm B C as will be sufficient to balance it on the prop I). This supposed, let P represent a power whose weight or purchase is equal to 1 pound, and let the weight of W equal 12 pounds, then, if the power be twelve times as far from the fulcrum as the weight is, they will exactly counterpoise; and a small addition of pur- chase to the power P will force it down, and raise the weight W; and the velocity with which the power descends will be to the velocity with which the weight rises, as 12 to l; that is, directly as their distances from the fulcrum, and, consequently, as the spaces through which they move. Hence, a man, who, by his natural strength, without the help of any machine, could support a hundred weight, will by the help of this lever be enabled to support twelve hundred. If the weight be less, or the power greater, the fulcrum may be placed so much farther from the weight; and then it can be raised to a proportionably greater height. For, universally, if the intensity of the weight multiplied into its distance from the fulcrum, be equal to the intensity of the power multiplied into its distance from the ful- crum, the power and weight will exactly balance each other; and a little addition to the power will raise the weight. Thus, in the present instance, the weight W is 12 pounds, and its distance from the fulcrum 1 inch; and 12 multiplied by 1 is 12; the power P is equal to 1 pound, and its distance from the prop is 12 inches, which multiplied by 1 is 12 again; and therefore there is an equilibrium between them. So, if a power squal to 2 pounds be applied at the distance of 6 inches from the fulcrum, it will just balance the weight W.; for 6 × 2 = 12, as before; and a power equal to 3 pounds placed at 4 inches’ distance, would be the same ; for 3 × 4 = 12; and so on in proportion. The statera, or Roman steelyard, explained under the word BALANCE, and used for finding the weights of different bodies by one single weight placed at different distances from the ful- crum or centre of motion D, (fig. 6,) is a lever of this kind. For, if a weight be hung at A, the extremity of the shorter arm D G is of such a weight as exactly to counterpoise the longer arm D X; if this arm be divided into any number of equal parts, each equal to O D, the single weight P will serve for weighing anything as heavy as itself, or as many times heavier as there are divisions in the arm D X, or any quantity between its own weight and that quantity. As for example: If P = 1 pound, be placed at the first division 1 in the arm D X, it will balance 1 pound in the scale at W ; if it be removed to the second division at 2, it will balance 2 pounds in the scale W ; if to the third, 3 pounds; and so on to the end of the arm DX. If each of these integral divisions be subdivided into as many equal parts as a pound contains ounces, and the weight P. be placed at any of these subdivisions, so as to counterpoise what is in the scale, the pounds and odd ounces therein will by that means be ascertained. 2. When the weight W lies between the fulcrum G and the power P, (fig. 2.) This kind includes the crow in its more general application, the baker's and druggist's knife, the com- being bent for the sake of convenience. mon door, the wheel-barrow, nut-crackers, and oars. In this, as well as the former, the advantage gained is as the distancé of the power to the distance of the weight from the fulcrum: for the respective velocities of the power and weights are in that proportion; and they will balance each other when the intensity of the power, multiplied by its distance, is equal to the intensity of the weight multiplied by its distance. Thus, if A B, be a lever on which the weight W of 6 pounds hangs at the distance of 1 inch from the prop G, and a power P, equal to the weight of 1 ounce, hangs at the end B, 6 inches from G, by the cord CD going over the fixed pulley E, the power will merely support the weight: and a small addition to the power will raise the weight 1 inch for every 6 inches that the power descends. This lever shews the reason why two men carrying a burden upon a stick between them, bear unequal shares of the burden in the inverse proportion of their distances from it. For the nearer either of them is to the burden, the greater share he bears of it: and if he goes directly under it, he bears the whole. So if one man be at G, and the other at B, having a pole or stick A B resting on their respective shoulders; if the burden be five times nearer G than A, the man G will bear five times as much as B. If the load G be only placed upon the pole PW, as in fig. 20, a vertical from the centre of gravity G, will in going up a hill divide the space unequally at C, and the lower person must therefore suffer a greater strain. Two horses of unequal strength may yet be yoked to draw equally, by a pro- portionate division of the bar. This is partly effected in the ordinary way, by attaching the perch to a short projection from the middle of the bar. To range a number of men along the arms of a pole, for the purpose of transporting heavy loads, is very unskilful, though frequently done in this country. Those who are nearest must evidently take the greatest share of the burden, while the remote bearers have not the means of exert. ing their strength. The method practised in the East is much preferable, the strain being successively subdivided by a sys- tem of levers crossing each other. - 3. When the power P is applied (fig. 3) between the fulcrum E and the weight W. To this kind belong the sheep-shears. It has a mechanical disadvantage, but admits of a proportion- ally wider motion. The bones of animals are therefore levers generally of this sort, pulled by the moderate contraction of muscles inserted nearer their joints or centre of motion than the centre of gravity of the weight to be raised. That there may be a balance in this lever, between the power and the weight, the intensity of the power must exceed the intensity of the weight just as much as the distance of the weight from the prop exceeds the distance of the power. For example, 1. pound placed three times as far from the prop E as the power P acts at F, by the cord C going over the fixed pulley D, the power must be equal to 3 lbs. to support the weight of 1 lb. Upon the principle of this lever, we see men raise ladders against a wall, and also the wheels of a clock move; because their moving power acts upon them near the centre of motion by means of a small pinion which is the fulcrum. - The Bent Lever, differs in nothing from the first, except in A B C, fig. 4, is a lever of this sort, bent at C, which is its fulcrum or centre of motion. P is the power acting upon the longer arm A C at F, by means of the cord DE going over the pulley G.; and W is a weight or resistance acting upon the end B of the shorter arm C B. If the power is to the weight as C B : C F, they are in equilibrium ; for if W = 5 lbs. acting at the distance of 1 foot from the centre of motion C, and P = 1 lb. acting at F, 5 feet from the centre C, the power and weight will just balance each other. The Universal Lever, is occasionally used for raising weights, but more commonly for dragging logs to the saw-pit. This is effected by annexing to the end of the short arm two claws, which work alternately in the teeth of a rachet wheel. In fact, the wheel and pinion are but an extension of the lever. One of the most ordinary and yet useful applications of the lever, is to weigh substances, or to compare their weights by means of a standard, as shewn in fig. 5, where the common balance, though less expeditious than the steelyard, as shewn in fig. 6, is yet capable of greater accuracy. As it has equal arms C E, DE, it requires a series of intermediate weights, 7 Z 638 M E C M, E: C DICTIONARY OF MECHANICAL SCIENCE. which are thrown into either scale A or B, and the whole is suspended on the pivot or fulcrum E. H. is a mere hook by which to suspend the machine. . For philosophical purposes, the easiest way is to reckon always by grains. The geometri- cal progression 1, 2, 4, 8, 16, 32, 64, &c. forms the simplest arrangement; but it will be found more convenient to follow the decimal division, and the successive sets of 1, 2, 3, and 4; 10, 20, 30, and 40; 100, 200, 300, and 400; 1000, 2000, 3000, and 4000, &c. would save much trouble in adding up the weights. . . . . . . A. False Balance has one arm, somewhat longer than the other. . But the fraud is easily detected, by interchanging the places of the weight, and the substance to be weighed; for the weight assigned will then be diminished, in the same propor- tion as it was before augmented. It perhaps deserves remark, that the true-weight is rather less than half the sum of those opposite indications. Suppose B D (fig. 21) to represent the true weight, and let B D be to B.A. in the ratio of the arms of | the fraudulent, balance; having completed the semicircle, it is evident that A B will indicate the weight of the substance when placed in the scale of the longer arm, and B C its weight when suspended from the shorter arm. But B D is less than the radius, or the arithmetical mean between A B and B C. Since, from the property of the semicircle, B D is a mean propor- tional or geometrical mean between A B and B C, the true weight of any body might be discovered even by means of a | false balance. Let it be weighed first in one scale, and then in the other; and, the results being multiplied together, the square root of their product will, give the accurate value. Every correct balance must, therefore, have arms of precisely equal lengths, or have its fulcrum placed equally distant from the extreme points from which the scales are suspended. But the delicacy of the instrument depends on the proximity of its fulcrum to the straight line joining those two points. To pre- serve. a stable equilibrium, however, it must occupy a position somewhat above that line. The beam should be strong and light, its preferable form consisting hence of two hollow cones: it should turn with a fine knife-edge upon a plate of agate, polished crystal, or hard steel ; and the scales should likewise be hooked from sharp edges. The sensibility is further aug- mented, and the risk of injury obviated, by various other Čontrivances, some of which we have already noticed in treat- ing upon this useful domestic machine. The Wheel and Aacle, (fig. 7,) is reckoned the next mechanical power, and it consists merely of a wheel A B attached to a small cylinder C D moving about the same centre; the power is applied to the circumference of the wheel, and the weight W to be raised has a cord Klapped about the cylinder. This in- strument may hence be regarded as a continued lever. The power is, therefore, to the weight, as the radius of the axle is to that of the wheel; or, if the principle of virtual velocities be preferred, the power and weight are inversely as the circum- ferences of the wheel and of its axle. If the circumference of the wheel be eight times that of the axle, then a power P = 1 lb. hanging by the cord I, which laps over the wheel, will balance a weight W = 8 lbs. hanging by the rope K, which goes round the axle, . If spokes S, S, S, or arms, be applied to the wheel, the circumference described by these must be con- sidered as the circle of action. In this sort of machines it is requisite to have a ratchet wheel on the end of the axle C, with a catch to fall into its teeth; which will at any time support the weight, and keep it from descending, if the person who turns the handle should, through inadvertency or carelessness, quit his hold while the weight is raising. Thus, by this means, the danger is prevented which might otherwise happen by the run- ning down of the weight when left at liberty. As varieties of the same instrument, we may name the Cap- stan or Windlass, and the Common Gin. In the latter, the rope which draws up the weight is wound about a drum, with a long projecting arm, which a horse puts in motion by treading round a circular path. Of a similar nature is the crane, driven by men or cattle, walking within its circumference; but here the purchase is only in the ratio of the distance of the point of im- pulsion from a vertical through the centre of the wheel, to the radius of the axle. The wheel and axle may turn also on dif- ferent centres, and have their circumferences connected in equal to two pounds. mutual action, either by means of a belt or strap, or by the indentation of a system of cogs or teeth. This arrangement is usually called Wheel and Pinion. The wheel has sometimes its axle of a tapered or conical shape, which gives it a varying purchase. This construction is adopted in the fusee of a watch, and is likewise employed advantageously in raising minerals, by an uniform pull from very deep pits, the rope at its greatest length being coiled about the narrow end of the axle, and advancing towards the wide end as it shortens. The Double Capstan is a very ingenious contrivance, origi- nally brought from China, for augmenting in any degree the efficacy of the wheel and axle, without reducing its strength. It consists of two conjoined cylinders of nearly equal diame- ters, turning about the same axis, the weight being supported by "the loop of a very long cord, of which one end uncoils from the smaller cylinder, while the other end laps constantly about the the annexed figure. The elevation of the weight at each revolution is therefore equal to half the difference between the two circumferences, and the effect of the arrangement is the weight had been wound about a cylin- der, which has a circumference merely equal to that quantity. The mecha- nical advantage of the instrument, combined with its pulley, is hence in cylinder to half its excess above that of the Smaller one. Nearly the same effect is procured, by employing a single conical axle; one part of the train of cord unrolling itself from the coiled up towards the larger end. The Pulley consists either of one moveable pulley, or a sys- tem of pulleys; some in a block or case which is fixed, and others in a block which is moveable, and rises with the weight. For though a single pulley that only turns on its axis, and larger cylinder, as represented in same as if the cord sustaining the the ratio of the diameter of the larger smaller end, while the other part is moves not out of its place, may serve to change the direction of the power, yet it can give no mechanical advantage thereto ; but is only as the beam of a balance, whose arms are of equal length and weight. Thus A, fig. 8, is a single pulley, and if it support the equal weights P and W, the cord B B to which they are appended, is equally stretched throughout, and the pulley A sustains both the weights, or is drawn with a force equal to twice P. It is properly but another form of the balance. In the pulley, fig. 8, No. 2, a power of one (P1,) will sustain twice its weight, (W 2,) the cord b B being stretched with a power of I, and the part from A to P with an equal power. - In a combination of three moveable pulleys, A B C, fig.9, con- nected by three distinct cords, each fastened at one end to an immoveable block above, the power of the whole is discovered by supposing two such weights, P and W, suspended so as to keep the machine in equilibrio, and then beginning with the least weight or power P, and considering what force each sepa- rate pulley sustains. Thus if P be one pound, the cord which sustains it acts at its other end upon the fixed block above, and is consequently re-acted upon by a force equal to one pound ; and the pulley A, as in fig. 8, is drawn with a force By tracing the second cord in the same manner, it will appear that the pulley B is drawn with twice the force of A, or four pounds; and C is drawn with twice the force of B, or 8 pounds. So that the purchase of this machine is such, that the weight W has 8 times the power of P. The velocity of the weight to that of the power is (in a simi- lar way of arguing) thus: if P descend 8 inches, A will ascend 4; B, 2 ; and C or W, 1 inch, so that the velocities are reci- procally as the power and weight. Another combination of pulleys, whereof two, A and B, fig. 10, run in the fixed block X; and two others C and D, in a moveable block, which raise the weight W ; by pulling the cord at P, which goes successively over the pulleys A, D, B, C, and M E C M. E.C. 639 , DICTIONARY | OF MECHANICAL SCIENCE. is fastened to the fixed blocks. The purchase of this machine. is known by considering that the cord is usually stretched throughout by putting two such weights, P and W, as will coun- terpoise each other: for P is sustained by the single cord, and W by four folds of the same, viz. by the parts, o, s, u, h, ; , so that if P be one pound, W will be four pounds. . . . . . . . The velocity of the power is to that of the weight as four to one, for if P deseend four inches, the parts of the cord at k will as- cend towards, e four inches, and all the other parts of the cord, from the pulley C, will equally follow each other, and C or W. will ascend one inch towards s; or the four parts of the cord o, s, w, k, will each be shortened one inch. - - In like manner may the purchase of any other combination of pulleys be determined: and it will always happen, that the momenta of the weight and power will be equal, as in other mechanical powers. That is, if any power will raise one pound with a certain velocity, the same power will raise two pounds with half that velocity, or one hundred pounds with one hun- dredth part of that velocity, &c. But as a system of pulleys has no great weight, and lies in a small compass, it is easily carried about; and can be applied, in a great many cases, for raising weights, where other engines cannot; but they have a great deal of friction on three accounts:–1. Because the diame- ters of their axes, bear a very considerable proportion to their own diameters. 2. Because in working they are apt to rub against one another, or against the sides of the blocks. 3. Because of the stiffness of the ropes that pass over and under them. - - The Inclined Plane is chiefly employed to facilitate excava- tions, and to raise the materials in buildings; and the advan- tage gained by it is as great as its length exceeds its perpen- dicular height. Let A B, fig. 11, be a plane parallel to the horizon, and C D a plane inclined to it; and suppose the whole length C D to be three times as great as the perpendicular height G fiſ'. In this case the cylinder E will be supported upon the plane CD, and kept from rolling down upon it, by a power equal to a third part of the weight of the cylinder. Therefore, a weight may be rolled up this inclined plane with a third part of the power which would be sufficient to draw it up by the side of an upright wall. If the plane was four times as long as it is high, a fourth part of the power would be sufficient; and so on in proportion. Suppose a man has occasion to set a weight upon an eminence, and the weight is so great that he cannot lift it by his natural strength, he will take a long stout plank, or something equivalent thereto, and setting it sloping, will push the weight before him up the plank, to the place de- signed to set it in ; and such plank, or other contrivance like it, is an inclined plane. Now it is evident that the shorter this inclined plane is, the steeper is the ascent; and the longer the plane is, the ascent must be the easier. It is plain also, that it is much easier to push a rolling weight E along a level A B, fig. 12, up a hill DC, fig. 11, that rises gently, than up a hill A B, fig. 13, which is very steep. The force where with a rolling body descends upon an inclined plane, is to the force of its absolute gravity, by which it would descend perpendicularly in a free space, as the height of the plane is to its length. For suppose the plane A B, fig. 12, to be paral- lel to the horizon, the cylinder will keep at rest on any part of the plane where it is laid. If the plane be so elevated, that its perpendicular height from D, fig. 13, is equal to half its length AB, the cylinder C will roll down upon the plane with a force equal to half its weight; for it would require a power (acting in the direction of A B) equal to half its weight, to keep it from rol- ling. If the plane DB, fig. 14, be elevated, so as to be perpendi- cular to the horizon, the cylinder C would descend with its whole force of gravity, because the plane contributes nothing to its support or hinderance; and therefore it would require a power equal to its whole weight to keep it from descending. To the inclined plane may be reduced all hatchets, chisels, &c. Of the Wedge.—The fifth mechanical power or machine is the wedge, which may be considered as two equally inclined planes D EF and C E F, joined together at their bases e E FO, fig. 15; then D C is the whole thickness of the wedge at its back A B C D where the power is applied; E F is the depth or height of the wedge; D F the length of one of its sides, equal to CF, the length of the other side; and O F is its sharp edge, which is the top or acting part of the wedge. entered into the wood intended to be split, by the force of a hammer or mallét striking perpendicularly on its back. Thus, A B, fig. 16, is a wedge driven into the cleft C E D of the wood F G. When the wood does not cleave at any distance before the wedge, there will be an equilibrium between the power impelling the wedge downward, and the resistance of the wood acting against the two sides of the wedge; when the power is to the resistance as half the thickness of the wedge at its back is to the length of either of its sides : because the resistance then acts perpendicular to the sides of the wedges. But when the resist- ance on each side acts parallel to the back,the power that balances the resistances on both sides will be as the length of the whole back of the wedge is to double its perpendicular height. When the wood cleaves at any distance before the wedge, (as it gene- rally does,) the power impelling the wedge will not be to the resistance of the wood as the length of the back of the wedge is to the length of both its sides, but as half the length of the back is to the length of either side of the cleft, estimated from For if we suppose the wedge to be lengthened down from the top CD, to the bottom of the cleft at E, the same proportion will hold ; namely, that the power will be to the resistance as half the length of the back of the wedge is to the length of either of its sides: or, which amounts to the same thing, as the whole length of the back is to the length of both the sides. - . The wedge is a mechanical power of singular efficacy, and the percussion by which its action is obtained; is precisely that force which we can with the greatest convenience almost inde- finitely increase. By means of the wedge, the walls of houses may be propped, rocks split, and the heaviest ships raised up, operations to which the lever, the wheel and axle, and the pulley, are either ill adapted, or entirely incompetent. To the wedge are referred the axe, the spade, chisels, needles, knives, punches, and, in short, all instruments which, beginning with edges or points, grow gradually thicker. A saw is a number of chisels fixed in a line ; and a knife, if its edge be examined with a microscope, will be found to be only a fine saw. Of the Screw.—The sixth and last mechanical power which we have to notice, is the screw. The screw, strictly speaking, consists of two parts, which work within each other. One of these parts, and which is always meant when the word screw is used alone, is a solid cylinder, on the circumference of which is cut a spiral groove;—specifically called an outside or convex: screw. The other part is a hollow cylinder, or at least, what- ever its external form may be, it contains a cylindrical hole, within which is cut a spiral groove corresponding to that of the convex screw, which can be turned within it, and the spiral pro- jections of one lock into the spiral hollows of the other. For the sake of necessary contradistinction, this latter part is called an . inside, a concave, or socket screw, when spoken of generally, without reference to any other use than its principal one, of an indispensable companion to the convex screw ; but when it consists of a small piece of metal, as for drawing tight bolts of any description, it is most commonly called a nut ; and when it is of considerable size, as for a large press or vice, it is usu- ally called a boa. The thread of a screw is its spiral projection ; the pace or step of a screw is the distance between the threads; and the groove or gorge is the hollow between the threads. To obtain an idea of the nature of the screw, and of its affi- nity to the inclined plane, cut a piece of paper in the form of an inclined plane, or half wedge, as A B C, fig. 17, and then wrap it round a cylinder, fig. 18: the edge of this plane or paper will form a spiral round the cylinder, which will give the thread of the screw. A screw is seldom used without the application of a lever to assist in turning it: it then becomes a compound machine of great force, either in compressing the parts of bodies together, or in raising great weights. . As the lever or winch must turn the cylinder once round before the weight or resist- ance can be moved from one spiral winding to another, or before the screw working in its box can rise or sink the dis- tance between the threads, as from a to b, therefore as much as the circumference of the circle described by the lever is greater than the pace of the screw, or distance between the threads, so much does the force of the screw exceed the motive force. For example, suppose the pace or distance of , the threads to be half an inch, and the length of the lever 12 inches, 640 M E C IM E C, DICTIONARY OF MECHANICAL SCIENCE. the circle described by the extremity of the lever where the power acts, will be about 76 inches, or 152 half inches, conse- quently, 152 times as great as the distance between two conti- guous threads; therefore if the intensity of the power at the end of the lever be equal to one pound, that single pound will ba- lance 152 pounds acting against the screw. If as much addi- tional force be exerted as is sufficient to overcome the friction, the 152 pounds may be raised; and the velocity of the power will be to the velocity of the weight as 152 to 1. Hence we may clearly perceive, that the longer the lever, and the nearer the threads to 9ne another, so much the greater is the force of the screw. The friction of the screw is very great, but we are indebted to this circumstance for a peculiar advantage in the use of this machine, which will sustain a weight, or press upon a body against which it is driven, after the power is removed or ceases to act. To enumerate all the uses of the screw, would be impossible. Among other purposes, it is applied to great advantage for measuring or subdividing small spaces; when thus applied it is called a micrometer, which may be made to indicate on an index plate, a portion of a turn, advancing the screw less than the fifty-thousandth part of an inch. The threads of screws are differently formed, according to the materials of which they are made, or the use for which they are intended. The threads of wooden screws are generally angular, that they may rest upon a broad base, and thereby have their strength increased to the utmost. Small screws, whatever material they are made of, are generally angular also, not only for the same reason as the wooden ones, but because the angular thread is the most easily made. The metal screws which are used for large presses, vices, &c. have generally a square thread, a form which gives great steadiness of motion. A thread of which the sides are parallel, and the top and bot- tom a little rounded, is perhaps the most perfect of all forms. In the common screw, to which the preceding observations are exclusively applicable, the threads are one continued spiral, from one end to the other; but where there are two or more se- rate spirals running up together, as in the worm of a jack, or the principal screw of a common printing press, the descent of the screw in a revolution will be proportionately increased ; and therefore whatever be the number of the spirals, they must, in calculating the power, be measured and reckoned as one thread. - The Endless Screw.—A screw is sometimes cut on an axle, to serve as a pinion, and by working in the circumference of a wheel; it is then called an endless screw, because it may be turned perpetually without advancing or receding, that is, with- out any other motion than a rotatory one. The threads of this screw are of the square form, and fit exactly into the spaces between the teeth of a wheel, which teeth are cut obliquely, to answer the threads. When the endless screw has been turned once round, the wheel has only made a portion of a turn equal to the distance between one of its threads; that is, the wheel has moved one tooth ; and therefore the number of its teeth is always the same as the number of the revolutions made by the screw before it once turned round. The construction and mechanical advantage gained by this screw may be best illustrated by a figure ; let the wheel C, fig. 19, have an endless screw a b working in the teeth of the wheel D, which suppose to be 48 in number. It is plain, that for every time the wheel C and screw a b are turned round by the winch A, the wheel D will be moved one tooth by the screw, and therefore, in 48 revolutions of the winch, the wheel D will be turned once round. Then, if the circumference of a circle, described by the handle of the winch A, be equal to the circum- ference of a groove e round the wheel D, the velocity of the handle will be 48 times as great as the velocity of any given point in the groove. Consequently, if a line G goes round the groove e, and has a weight of 48 pounds hung to it below the pedestal EF, a power equal to one pound at the handle will balance and support the weight. To prove this by experiment, let the circumferences of the grooves of the wheels C and D be equal to one another; and then if a weight A, of one pound, be suspended by a line going round the groove of the wheel C, it will balance a weight of 48 pounds hanging by the line G ; and a small addition to the weight H, will cause it to descend, and” so raise up the other weight. - - If a line G, instead of going round the groove e of the wheel D, goes round its axle, 1, the power of the machine will be as much increased as the circumference of the groove e exceeds the circumference of the axle : which supposing it to be six times, then one pound at H will balance six times 48, or 288 pounds, hung to the line on the axle; and hence the power or advantage of this machine will be as 288 to 1. That is to say, a man, who by his natural strength could lift an hundred weight, will be able to raise 288 by this engine. The use of the endless screw affords a very ready means of greatly dimi- nishing a rotatory motion, and accomplishes at once what would otherwise require the intervention of two or three wheels; and although it operates slowly by a sliding motion, it has not probably more friction than any of the less simple combinations which might be employed to effect the same object. It possesses the advantage too, of moving a wheel with much more steadi- ness than a pinion, when the workmanship of both is of equal quality. This circumstance is not so much regarded by me- chanics as perhaps it ought, and therefore the endless screw is often not used when it would be advantageous. The principal restriction to the use of this screw is, its being so liable to wear when its motion is very rapid : a rapid motion, therefore, should not be assigned to it, unless it be made of hardened steel, when the objection will be less forcible. The coining engine consists of a screw carrying ponderous arms. The impulsion accumulated by the swing produces a stroke similar to the concentrator of force ; but the violence of the blow is softened, and the shock partly consumed, by the prolonged friction of the slanting grooves of the screw, by which the stamper advances to the die. As the endless screw, working in the teeth of a wheel, has its energy multiplied by their number, it is evident that it may act at once on two ratchet wheels divided almost alike, the difference in breadth between the parallel teeth being the space of exertion. By such a contrivance, which also reckons the revo- lutions, the mechanical purchase might be carried to any extent. The Concentrator of Force, an engine that exhibits in a striking manner the accumulation and transfer of impulsion * among bodies, may be regard- ed as, next to Atwood’s inge- nious machine, an import- ant addition to illustrative philosophical apparatus,since it not only sheds a clear light on some abstruse parts of me- chanical theory; but may with advantage be directed, in a variety of important cases, to the practice of the arts. The concentrator consists of a ponderous wheel, composed of a thin circle of iron, load- ed at the circumference with a broad swelling ring of lead, and fixed to a strong steel axle. To this axle is likewise attached several short cy- linders, of different diameters, the smallest formed of brass, and divided into two parts, that are capable of locking together at pleasure. The axle, placed in a horizontal position, moves upon gudge- ons on the top of a high solid frame; and the machine may be set in motion by turning a winch, or by the descent of a small weight fastened to a silk line, which passes over a pulley, and is lapped round one of the barrels. The fig. represents one of the best mo- dels that has yet been used, the frame being five feet in about 18 pounds weight, and is 17 inches height; the wheel has M E C M E C DICTIONARY OF MECHANICAL SCIENCE. 641 in diameter, whilé the diameters of the successive barrels are only 6, 4 and 2 inches. The principal application of this engine is to raise from its platform any great weight. If 1 pound, for instance, in descending through thirty feet, gradually commu- nicate its impression to the wheel, and, the instant it reaches the ground, the detached part of the brass barrel should lock, and catch hold of the loop of acord holding half a hundred weight, or 56 pounds, this mass will be almost immediately lifted up near 6 inches, and there suspended. But what is remark- able, and appears at first sight paradoxical, the effect is pre- cisely the same about whatever barrel the line, be wound. The result is quite altered, when different descending weights are used, the elevation produced being always proportional to them. Thus, the descent of 2 and 4 pounds through 30 feet, will raise 56 pounds to nearly 1 and 2 feet. It is not difficult to explain generally these effects. Let the descending power be very small in comparison with the weight of the ponderous wheel, and suppose its action at first to be exerted at the rim. This rim, in which is condensed the entire mass, will now describe a space equal to the measure of de- scent, and the whole power may be considered as inciting its revolution. Consequently the square of the velocity acquired by the wheel must be proportional to the descending power multiplied into the space through which it falls. When the accelerating force acts upon a barrel smaller than the wheel, the energy exerted at the rim is proportionally diminished, but the space described by it is augmented in the same ratio, and therefore the square of the velocity resulting from those combined causes will continue unaltered. The square of the velocity, or measure of impulsion, is extinguished by the efforts expended in raising the weight; wherefore the power, multi- plied into the quantity of descent is E the weight x into its corresponding ascent. Hence the power and the weight are inversely proportional to the spaces which they severally describe. Leslie, who has very fully examined this matter, gives a very rigid formula in exemplification of this principle, from which he shews that the fall of 2 lbs. through 30 feet would lift 500 lbs. over 1 inch and a third part; and if the force be accu- mulated, the concentrator will prove sufficient to start the greatest load, or overcome the most powerful obstacle. In- stead of raising great weights, the concentrator might be adapted to tear asunder thick wires or metallic rods. The power exerted will then be inversely as the spaces through which those rods stretch, before they suffer fracture. The effects will consequently be augmented, by shortening the lengths of the rods. To the bottom of the engine, screw a strong bar above 4 feet in height, and to this fasten rods from 6 inches to a foot long. If the limit of extension, which pre- cedes the final disruption, were only half an inch, the power exerted, though produced by the descent of a single pound, would amount to about 1500 lb. A rigid and unyielding body is hence the most easily torn or broken. But the impetus accumulated by the concentrator may be wholly consumed, in merely stretching a very elastic substance of sufficient length. If a light contorted spring, for instance, be opposed to the rotation of the mass, it will, by its large though languid exten- sion, gradually destroy the motive energy. A thick woollen cord, loosely plaited, and tied to a ring at the bottom of the machine, will produce a similar effect. A slender hempen string, which has little of a stretching quality, may still serve the same purpose, if it be taken of an adequate length. It is only required that half the final strain multiplied into the cor- responding extension should be equal to the product of the falling weight by its quantity of descent. A tension of 60 lb., acting through a height of one foot, would be sufficient to muſtle and extinguish the momentum of rotation generated by the descent of one pound through 30 feet. To produce this effect, therefore, it is only wanted to select such a length of cord as will extend one foot, by the application of a strain of 120 lbs. A more slender substance, if proportionally more stretching, would have the same effect. In either case, a weight exceed- ing the absolute tension, and attached to the end of the string, would not, during the moderated consumption of the shock, be stirred in the slightest degree from its place. The strength of a cord depends on its thickness, but the power to resist impul- 66. sion is determined by its elasticity and its length. This prin- ciple, which has been much overlooked, enters largely into the consideration of practical mechanics. Hence the practice of stemming a ship's way into a harbour by the friction of a long rope, the momentum being thus gradually spent. A short rope, firmly fastened to the pier head, so far from staying the vessel, would instantly snap. For the same reason, a ship riding at anchor is obliged to lengthen her cables. When these are composed of chains, the tension resulting from a diminution of curvature is precisely the same as if a contractile force had been exerted. It is perhaps a general error in civil architec- ture to aim at mere solidity. Lightness and elasticity com- bined will often resist the shocks of ages, while stiff and pon- derous materials are crumbled into ruins. - If the barrels be of 2 and 3 inches radii, then will the time of generating the impulsion be compounded of the inverse ratio of the radius of the barrel, and the inverse subduplicate ratio of the falling body, with the direct subduplicate ratio of the space of descent; while the time of expanding this impulsion is inversely as the weight to be raised, and directly in the sub- duplicate ratio of the falling body and of its descent. Thus one pound having a line curled about the smallest barrel, will descend through 30 feet in § V (18.30) seconds, or 46%"; con- nected with the middle barrel it would descend in 234"; but applied to the largest barrel it would only require 15}". The succeeding act of lifting 112 lbs. will occupy five-sixths of a second. Also, the impulsion which required 463" to accumu- late, exerts in ascension a strain of 1500 lbs., which is suffi- cient to tear a rod of metal asunder in less than the thirtieth part of a second; for the greater the weight to be raised, the more rapid is the act of ascension; and it is the same thing, whether an obstacle be overcome, or a disruption effected. The slowness with which this impulsive energy collects, is-re- markably contrasted with the rapidity of its subsequent dis- charge. The greatest effects may be concentrated within such a portion of time as eludes the observation of the senses, and appears really instantaneous. - The Concentrator of force thus finely elucidates the acquisi- tion and the transfer of impulsive energy. The same accumu- lated momentum produces diversified effects, according to the way in which it is disposed. It will raise a ponderous mass, tear asunder a solid body, or will expend all its action in merely stretching a substance of a very distensible quality. These different purposes are attained in the operations of the mechanical arts; but sound theory is yet required to guide and improve the practice. This engine, constructed on a large scale, might hence, with obvious advantage, be adopted as a most powerful auxiliary in various operations of art. Many situations occur which require an immense effort to be made on a sudden, and within a very limited space. This can be accomplished only by storing up, as it were, a magazine of force, which may be opened and discharged at some precise moment. Even moderate animal exertion, if applied during any considerable time, will communicate to the concentrator an impulsion sufficient to burst the firmest obstacles, and to lift, through a short space, the most enormous loads. This engine involves likewise the theory of the Fly which is annexed to various machines, not to augment their power, but merely to equalize their motion. The variable inciting forces are thus, by the intervention of a heavy wheel, blended together in creating one great momentum, which afterwards main- tains a nearly uniform action. The use of the fly in mechanics hence resembles a reservoir, which collects the intermitting currents, and dispenses its water in a regular stream. Though it is evident, from the foregoing principles, that any one of the mechanical powers is capable of overcoming the greatest possible resistance, in theory; yet, in practice, if used singly for producing very great effects, they would frequently be so unwieldy and unmanageable, as to render it impossible to apply them. For this reason, it is generally found more advantageous to combine them together; by which means the power is more easily applied, and many other advantages are obtained. Of the various machines which have been contrived to illustrate the simple mechanical powers, or to illustrate their effects, we select the following:— - 8 A 642 M E C M. E. C DICTIONARY OF MECHANICAL SCIENCE. º Machine in which all the Mechanical powers are combined.—The lever A B, plate II, fig. 1, whose centre of motion is C, is fixed to the endless screw DE, which drives the wheel and axle FH G. Round the axle G is coiled a rope G H I, passing round the four pulleys K, L, m, n, and fixed to a hook at m on the lower block, which carries the weight W. When equal weights are suspended on the lever at equal distances from the fulcrum C, the lever becomes a balance, and the wedge and inclined plane are evidently included in the endless screw DE. If the wheel F has thirty teeth, if the lever A B is equal to twice the diameter of the wheel F H, and if the diameter of the axle G. is one-tenth of the diameter of the wheel, a power of 1 exerted at P will raise a weight of 2400 suspended at the lower block of the four pulleys. - Machine for illustrating the Theory of the Wedge. — This machine is represented in fig. 2, where KILM and LMNO are two flat pieces of wood joined together by a hinge at L. M.; Pis a graduated arch on which these pieces of wood can be moved so as to subtend any angle not greater than 60°, and a, b, two screws for fixing them at the required angle. The back of the wedge will therefore be represented by IKNO, its sharp edge by LM, and its two sides by KILM, LMN 9. The weight p suspended to the wedge by the hook M, and the weight of the wedge itself, may be considered as the force employed to drive the wedge. The wooden cylinders A B, C D, have their extremities made like two flat circular plates, to prevent the wedge from slipping off at one side. To the pivots of these cylinders, two of which are represented at e and f, are fastened the cords e\W, fū, CW, A X, which passing over the pulleys U. W, X, W, are fastened to the two bars w v, a w, on which any equal weights Y, Z, may be hung at plea- sure. The tendency of these weights is evidently to draw the cylinders towards each other, and they may therefore be regarded as the resistance of the wood acting against the sides of the wedge. The cylinders themselves are suspended by their pivots to the threads E, F, G, H, which may be fixed to the ceiling of the room, or to the horizontal beam of a frame made on purpose. By placing various equal weights at Y and Z, it may be easy to determine the proportion between the power and the resistance when the wedge is in equilibrio. In this machine the impelling power is the pressure of the weight p, whereas, in the real wedge, the impelling power is always an impulsive force, which is infinitely more powerful. - Machine for trying the Strength of Material,—The piece of wood, whose strength is to be tried, is represented by E.F, fig. 3, and the force is applied to it by means of the winch A, which winds up the rope B C, passing over the pulley n, and below the pulley m, and attached to the point D of the beam E. F. The pulleys slide on two parallel bars fixed in a frame, held down by a projecting point at G, of the lever G R, which is graduated like a steelyard, and measures the force employed. The beam EF is held by a double vice IK with four screws, two of which are invisible. When a wire is to be torn, it is fixed to the cross bar L. M.; and when any body is to be crushed, it must be placed beneath the lever N 0, the rope B C being fixed to the hook N, and the end O being held down by the click which acts on the double ratchet O P. The lever is double from O to Q, and acts on the body by a loop fixed to it by a pin, from which this drawing and description are taken. - CoM Pound MACHINes, AND THE Construction of MACHI- NERY.—In this article we shall confine ourselves strictly to its title, as we have under their respective names described and illustrated the Centre of Gravity of Bodies, Friction, Motion, Inertia, &c.—Compound machines are all such as consist of a combination of the several simple machines, or mechanical powers, of which a description has been already given. To the varieties which appear under all the forms of association, scarcely any boundaries can be assigned; and as science advances, the number will continue to increase till it approxi- mates to infinity. These compound machimes are again classed under different denominations, according to the agents by which they are put in motion, the purposes they are intended to effect, or the art in which they are employed. Hence we have hydraulic, pneumatic, military, and architectural ma- chines, with a variety of others, which are elsewhere described under their respective heads. variable movements. Number of Height to which Time epoployed Duration of the Pounds raised. the Weight was in raising each Labour. Authorities. raised. . . Lift. . - s 1000 180 60 minutes, Euler. w º : 1) : 1 second, 8 hours, Bernouilli. . . .25 × 3 *} g 145 secs. | Amontons. 1765 3. 15 g. || 1 second, half anhour|Coulomb. | 1000 : 330 - 60 minutes, Desaguliers 1000 225 |60 minutes, . . . lSmeaton. 30 3% 1 second, 10 hours, Emerson. 29 Or 30 2'45 1 second, |Schulze. The impelled and working parts of a machine are generally connected by means of toothed wheels, so constructed as to produce the surest motion and most regular velocity. But it happens in most machines, that from their very construction, as well as from inequalities in the resistance to be overcome, and the nature of the impelling power, the momenta of their parts proving 'insafficient to equalize these irregularities, fly wheels are adopted for regulating and rendering uniform their See FLY WHEEL. . First Movers of Machinery are: 1. Animal strength, used as a moving power, may be employed in turning a windlass by a winch, in carrying burdens, or drawing, as the horse; 2. The application of wind, as in the wind mill, which see;—3. The impelling power of water for mills;—and the tremenduous force of steam. * ~! - TABLE of the Strength of Men, according to different Authors. According to Amontons, a man weighing 133 pounds French, ascended 52 feet French by steps in 34 seconds, but was com- pletely exhausted. The same author informs us that a sawer made 200 strokes of 18 inches French each, with a force of 25 pounds, in 145 seconds; but that he could not have continued the exertion above three minutes. - - It appears from the observations of Desaguliers, that an or- dinary man can, for the space of ten hours, turn a winch with a force of 30 pounds, and with a velocity of two feet and a half per second ; and that two men working at a windlass with han- dles at right angles to each other, can raise 70 pounds more easily than one man can raise 30. The reason of this is, that when there is only one man, he exerts variable efforts at diffe- rent positions of the handle, and therefore the motion of the windlass is irregular; whereas in the case of two men, with handles at right angles, the effect of the one man is greatest when the effect of the other is least, and therefore the motion of the machine is more uniform, and will perform more work. Desaguliers also found, that a man may exert a force of 80 pounds with a fly when the motion is pretty quick, and that, by means of a good common pump, he may raise a hogshead of water 10 feet high in a minute, and continue the exertion during a whole day. A variety of interesting experiments upon the force of men were made by the learned M. Coulomb. He found that the quantity of action of a man who ascended stairs with nothing but his own weight, was double that of a man loaded with 223 pounds avoirdupois, both of them continuing the exertion for a day. In this case the total or absolute effect of the unloaded man is the greatest possible; but the useful effect which he produces is nothing. In the same way, if he were loaded to such a degree that he was almost incapable of moving, the useful effect would be nothing. Hence there is a certain load with which the man will produce the greatest useful effect. This load M. Coulomb found to be 1738 pounds avoirdupois, upon the supposition that the man is to ascend stairs, and continue the exertion during a whole day. When thus loaded, the quantity of action exerted by the labourer is equivalent to 183:66 pounds avoirdupois raised through 3282 feet. This method of work- ing is however attended with a loss of three-fourths of the total action of the workman.—It appears also from Coulomb's expe- riments, that a man going up stairs for a day raises 205 chilio- grammes (a chiliogramme is equal to three ounces five drams avoirdupois) to the height of a chiliometre (a chiliometre is equal to 39571 English inches); that a man carrying wood up Mºchianics. PL. II. | * *** - | | | | Combinº all the Mechanical Powery | Machine to tºlustrate the Theory | Lºſ Bare ºſtly. Fº p. 662. M E C M E C 643 DICTIONARY OF MECHANICAL SCIENCE. rº. stairs raises, together with his own weight, 109 chiliogrammes to one chiliometre;—that a man weighing 150 pounds French, can ascend by stairs three feet French in a second, for the space of 15 or 20 seconds;–that a man cultivating the ground performs 3; as much labour as a man ascending stairs, and that his quantity of action is equal to 328 pounds avoirdupois raised through the space of 3282 feet:—that a man with a winch does § as much as by ascending stairs, and that in a pile engine, a man by means of a rope drawn horizontally, raised for the space of five hours 553 pounds French through one foot French in a second. When men walk on a horizontal road, Coulomb found that the quantity of action was a maximum when they were loaded, and that this maximum quantity of action is to that which is exerted by a man loaded with 190°25 pounds avoirdu- pois as 7 to 4.—The weight which a man ought to carry, in or- der that the useful effect may be a maximum, is 1653 pounds avoirdupois. When the workman, however, returns unloaded for a new burden, he must carry 2007 pounds avoirdupois. According to Dr. Robinson, a feeble old man raised seven cubic feet of water = 437-5pounds avoirdupois, 113 feet high in one minute, for eight or ten hours a day, by walking back- wards and forwards on a lever ; and a young man weighing 135 pounds, and carrying 30 pounds, raised 9% cubic feet of water = 578.1 pounds avoirdupois, 11% feet high, for 10 hours a day, without being fatigued. - From the experiments of Mr. Buchanan, it appears that the forces exerted by a man pumping, acting at a winch, ringing, and rowing, are as the numbers 1742, 2856, 3883,4095. - According to Desaguliers and Smeaton, the power of one horse is equal to the power of five men. Several French authors suppose a horse equal to seven men, while M. Schulze consi- ders one horse as equivalent to 14 men.—Two horses, accord- ing to the experiment of Annontous, excrtcd a force of 150 pounds French, when yoked in a plough. According to Desa- guliers, a horse is capable of drawing, with a force of 200 pounds, two miles and a half an hour, and of continuing this action eight hours in the day. When the force is 240 pounds he can work only six hours. It appears from Smeaton's re- ports, that by means of pumps a horse can raise 250 hogsheads of water, 10 feet high, in an hour.—The most disadvantageous way of employing the power of a horse is to make him carry a load up an inclined plane, for it was observed by De la Hire, | that three men, with 100 pounds each, will go faster up the in- clined plane than a horse with 300 pounds. When the horse walks on a good road, and is loaded with about two hundred weight, he may easily travel 25 miles in the space of seven or eight hours. * When a horse is employed in raising coals by means of a wheel and axle, and moves at the rate of about two miles an hour, Mr. Fenwick found that he could continue at work 12 hours each day, two and a half of which were spent in short intervals of rest, when he raised a load of 1000 pounds avoir- dupois, with a velocity of 13 feet per minute;—and that he will exert a force of 75 pounds for nine hours and a half, when moving with the same velocity. Mr. Fenwick also found that 230 ale gallons of water delivered every minute on an overshot water-wheel 10 feet in diameter; that a common steam engine, with a cylinder eight inches in diameter, and an improved engine with a cylinder 6:12 inches in diameter, will do the work of one horse, that is, will raise a weight of 1000 pounds avoir- dupois, through the height of 13 feet in a minute. It appears from Mr. Smeaton’s experiments, that Dutch sails in their com- mon position with a radius of 9 feet and a half, that Dutch sails in their best position with a radius of eight feet, and that his enlarged sails with a radius of seven feet, perform the same work as one man ; or perform one-fifth part of the work done by a horse. - Before concluding, we must revert to a circumstance which we have already noticed briefly, respecting the most efficient mode of employing the power of that useful, but very much abused animal, the horse. That the line of draught is often in a direction injurious to the horse, and tending to diminish his power as a mover of mechanism, will be evident to any person who considers the form of his shoulders. At the place where the neck rises from the chest, (see fig. 9, plate 1,) the shoulder blades form the resting place of his collar or harness into a slope, ap. This slope or inclination forms an angle with a perpendicular to the horizon, of about fourteen or fifteen degrees; and therefore the line of traction or draught should form the same angle with the horizon, because he will then pull perpendicularly to the shape of his shoulder, and all parts of that shoulder will be equally pressed by the collar. Besides, in overcoming obstacles, the advantage of this inclined direc- tion is mechanically great. Call a, fig. 10, plate IV. a wheel, b an obstacle, c the axle of the wheel, d the spoke which sus- tains the weight. A line drawn from the nearest part of the horizontal line of draught c k, to the fulcrum or obstacle at e, will form the acting part of a lever ge; and another line e d, being drawn from the fulcrum e to the nearest part of the spoke d, will form the resisting part of the same lever. Now, as the acting and resisting arms of the lever are of equal lengths, the lever becomes a scale-beam, and draught in the line g k must be equal to the weight of the wheel and all that it sustains, besides the friction; for if g ed be a crooked lever, a pull at g must be equal to all the weight supported by d. But when a horse draws agreeably to the shape of his shoulders in the line c k, the acting part of the lever he is lengthened nearly one- fourth; so that if it would require a pull at g equal to four hundred weight, a power applied at h will draw the wheel over the obstacle b with three hundred weight. To those unacquainted with the principles of mechanics, this truth may be easily proved by an ordinary scale-beam. The horse him- self, considered as a lever, has in this inclined draught a mani- fest advantage over his obstacles, in comparison of a horizon- tal draught, as may be seen by fig. 9. When the horse is yoked to a post, or has any great obstacle to overcome, he converts himself into a lever, making his hind feet the fulcrum, and the centre of gravity of his body to lean over it, at as great a distance as possible, by thrusting out his hind feet; by this means, acting both by his weight and muscular strength, and lengthening the acting part of the lever a b, he overcomes the difficulty more by his weight than by his muscular strength, for the muscles of the fore legs act upon the bones to so great a mechanical disadvantage, that though he exerts them with all his might, they serve, in great efforts, for little more than props to the fore part of his body. Hence we see the great use of heavy horses for draught. But the great mechanical use and advantage of the inclined line of draught may be more particularly seen, by calling the line a b, fig. 9, the acting part of the lever and the nearest approach from the fulcrum b to the inclined line of draught, (that is, b c) the resisting part of the lever: compare this with the resisting part of a lever touching the horizontal line of draught, (that is, b d.) and it will be found nearly double; in consequence, agreeably to the known properties of the lever, a weight at g would require double the exertion in the horse to remove it, that the same weight would require were it placed at e. Hence it is evident, that in economizing animal strength, single-horse carts are preferable to teams, because in a team, all but the shaft horse must draw horizontally, and consequently in a manner incon- sistent with their structure, and the established laws of mechanics. - ON THE Teeth of Wheels. –When one wheel impels another, the impelling power will sometimes act with greater, and sometimes with less force, unless the teeth of one or both of the wheels be parts of a curve generated after the manner of an epicycloid, by the revolution of one circle along the con- vex or concave side of the other. When one wheel so impels another, then their motion is uniform. To illustrate this, and shew the application of the cycloid and epicycloid, to give form to the teeth of wheels, let a circle B, proceed in a straight line on the plane C D, fig. 11, plate III. and at the same time revolve round its centre, till every part of the circumference has touched the plane, a point or pencil at a, which was lowest at the commencement of the motion, will have described the curve C E D, which is called a cycloid, and is evidently compounded of a rectilinear and circular motion. If a circle A, fig. 12, roll from 0 to q, on the convex circum- ference of another circle B, the point o will describe the curve op q, which is called an eacterior epicycloid; and if the circle A were to roll on the concave circumference of the circle B, as from r to s, the point r would describe an interior epicycloid, 644 M E C M E C. DICTIONARY of MECHANICAL scIENCE. In all these cases, the circle by which the curve is obtained, is called the generating circle; and one wheel will not drive another with uniform velocity, unless the teeth of one or more of the wheels have their acting surfaces formed into a curve generated after the manner of an epicycloid. But it is not absolutely necessary that the teeth of one or both wheels be exactly epicycloids; for if the teeth of one of them be either circular or triangular, with plain sides, or like a triangle with its sides converging to the centre of the wheel, or of any other form, uniformity of force and motion will be attained, if the teeth of the other wheel have a figure which is compounded of that of an epicycloid and the figure of the teeth of the first wheel. From a variety of cases, we select such forms for the teeth as are best adapted to practice. There are three differ- ent ways in which the teeth of wheels may act upon one another; and each mode of action requires a different form for the teeth :– - - g - • * : * 1st. When the teeth of the wheel begin to act upon the leaves of the pinion just as they arrive at the line of centres; and their mutual action is carried on after they have passed this line. 2d. When the teeth of the wheel begin to act upon the leaves of the pinion before they arrive at the line of centres, and conduct them either to this line, or a very little beyond it. 3rd. When the teeth of the wheel begin to act upon the leaves of the pinion before they arrive at the line of centres, and continue to act after they have passed that line. For the first, the acting faces of the leaves of the pinion should be parts of an interior epicycloid, generated by a circle of any diameter rolling, upon the concave superficies of the pinion; and the acting surfaces of the teeth of the wheel should be portions of an exterior epicycloid, formed by the same generating circle rolling upon the convex superficies of the wheel. Now, it is demonstrable, that wheir ouc circle rolls within another whose diameter is double that of the rolling circle, the line generated by any point of the latter will be a straight line tending to the centre of the larger circle. If the generating circle, therefore, mentioned above, should be taken with its diameter equal to the radius of the pinion, and be made to roll upon the concave superficies of the pinion, it will generate a straight line tending to the pinion's centre, which will be the form of the acting faces of its leaves; and the teeth of the wheel will in this case be exterior epicycloids, formed by a generating circle, whose diameter is equal to the radius of the pinion, rolling upon the convex superficies of the wheel. This construction of the teeth of the wheel, and leaves of the pinion, is represented by fig. 13, plate III. ; it is strongly recommended by De la Hire and Camus, and is perhaps the most advantageous, as it requires less trouble, and may be executed with greater accuracy, than if the leaves of the pinion had been curved as well as the teeth of the wheel.—The small wheel is the pinion ; its teeth are called leaves; and the line joining their centres, is called the line of centres. Lanterns or trundles, which consist of cylindrical staves fixed by both ends nearly at the circumferences of two equal circular boards, and which are so frequently substituted by millwrights for pinions, may often be adopted with great pro- priety, provided the teeth of the wheels working in them have a proper form. The following construction possesses the merit of diminishing the friction arising from the mutual action of the stayes and the teeth, and is easily reduced to practice. Let A, fig. 14, plate III., be the centre of the small wheel or trundle T C H Q, whose teeth are circular like ICR, having their centres in the circle PDE Y. Upon B, the centre of the large wheel, at the distances B C, B D, describe the circles FC K, G D O ; and with PD EY, as a generating circle, form the exterior epicycloid DN M, by rolling it upon the con- vex superficies of the circle G D O. The epicycloid D N M thus formed, would have been the proper form for the teeth of the largé wheel G D O, had the circular teeth of the small wheel been infinitely small; but as their diameter must be considerable, the teeth of the wheel should have another form. In order to determine their proper figure, divide the epicy- cloid DN M into a number of equal parts, 1, 2, 3, 4, &c. and let these divisions be as numerous as possible. Then, upon the points. 1, 2, 3, &c. as centres, with the distance D C equal to the radius of the circular tooth, describe portions of circles | the wheel are cylindrical. similar to those in the figure; and the curve OPT, which touches these circles, and is parallel to the epicycloid DNM, will be the proper form for the teeth of the large wheel. In order that the teeth may not act upon each other till they reach the line of centres A B, the curve O P should not touch the circular tooth I C R till the point O has arrived at D. The tooth O P, therefore, will commence its action upon the circu- lar tooth at the point I, where it is cut by the circle D R E. On this account, the part I C R of the cylindrical pin bein superfluous, may be cut off, and the staves of the trundle .# then be segments of circles similar to the shaded part.of the figure. : The second mode of the mutual action of wheels and pinions above-mentioned is not so advantageous as the former, and therefore should, if possible, be avoided. It is evident, that when the tooth of the wheel acts upon the leaf of the pinion before they arrive at the line of centres, and quits the leaf when they reach this line, that the tooth works deeper and deeper between the leaves of the pinion the nearer it comes to the line of centres; hence friction arises, because the tooth does not, as before, roll upon the leaf, but slides upon it; and from the same cause, the pinion soon becomes foul, as the dust which lies upon the acting faces of the wheels is pushed into the hollows between them. One advantage, however, attends this mode; it allows us to make the teeth of the large wheel rectilinear, and thus renders the labour of the mechanic less, and the accuracy of his work greater, than if they had been of a curvilinear form. If the teeth, therefore, of the wheel are made rectilinear, having their surfaces directed to the wheel's centre, the acting surfaces of the leaves must be epicycloids formed by a generating circle, whose diameter is equal to the sum of the radius of the wheel, added to the depth of one of its teeth, rolling upon the circuluference of the pinion. But if the teeth of the wheel and the leaves of the pinion are made curvilinear, the acting surfaces of the teeth of the wheel must be portions of an interior epicycloid formed by any generating circle rolling within the concave superficies of the large circle, and the acting surfaces of the pinion's leaves must be portions of an exterior epicycloid, produced by rolling the same gene- rating circle upon the convex circumference of the pinion. When the teeth of the large wheel are cylindrical spindles, either fixed or moveable upon their axis, an exterior epicy. cloid must be formed like D NM, in fig. 14, plate III., by a generating circle, whose radius is A C, rolling upon the con- vex circumference F C K ; A C being in this case the diameter of the wheel, and F C K the circumference of the pinion. By means of this epicycloid, a curve OPT must be formed as before described, which will be the proper curvature for the acting surfaces of the leaves of the pinion, when the teeth of In determining the relative diameter of the wheel and pinion for this mode of action, the radius of the wheel is reckoned from its centre to the extremity of its teeth, and the radius of the pinion from its centre to the bottom. of its leaves. The third way alluded to above, in which one wheel may drive another, namely, “when the teeth of the wheel begin to act upon the leaves of the pinion, before they arrive at the line of centres, and continue to act after they have passed that line,” remains to be considered. It is represented by fig. 1, plate IV., and as it is a combination of the two first modes, it partakes both of their advantages and disadvantages. It is evident from the figure, that the portion eh of the tooth acts upon the part b c of the leaf till they reach the line of centres A B, and that the part e d of the tooth acts upon the portion b a of the leaf after they have passed that line. It follows, there- fore, that the acting parts e. h and b c must be formed accord- ing to the directions given for the first mode of action, and that the remaining parts ed, b a, must have that curvature which the second mode of action requires; consequently e h should be part of an interior epicycloid formed by any generating circle rolling on the concave circumference of the wheel, and the corresponding part be of the leaf should be part of an exterior epicycloid formed by the same generating circle roll- ing upon b Eo, the convex circumference of the pinion; the remaining part ed of the tooth should be a portion of an exte- rior epicycloid, formed by any generating circle rolling upon | º - º | - | * * | - * º º § - | - º - * - s: º* º - > \|- N sº- - | ºr. º º N. C - | | s' s s | S. º - - - - - N. | | | | | * . - | * s | | | N N N N NNNN N. º º N Nº NIL. | - - | S. - - | - | * > | - | | | | |º |||||||||||| *|| || || 7 || - * | E-E-L || || |A| - F H. . s: | | || -- - 'S º N | | º - | - º º - - | - ſº S. º | | | a A | 4 || | II. | "|| | | - - M E C M E C DICTIONARY OF MECHANICAL SCIENCE. 645 e L, the convex superficies of the wheel; and the correspond- ing part b g of the leaf should be part of an interior epicycloid described by the same generating circle rolling along the con- cave side b E o of the pinion. But, as in practice, the produc- tion of this double curvature of the acting surfaces of the teeth would be exceedingly troublesome to the workman, who would probably never correctly accomplish his object, his labour may be abridged by making e k and b a radial lines, that is, e h a straight line tending to the centre of the wheel B, and b a like- wise a straight line tending to the centre A., of the pinion. The foregoing remarks apply to those cases in which the wheel drives the pinion. When the pinion drives the wheel, the form that has been directed to be given to the teeth of the wheel must be given to the leaves of the pinion, and that assigned to the leaves of the pinion must be given to the wheel. Another method of forming the teeth, which has had many advocates, consists of making the acting faces of the teeth invo- lutes of the wheel's circumference. Thus let A B, fig. 2, plate IV. be a portion of the wheel on which the tooth is to be fixed, and let A p m be a thread wrapped round its circumference, having a loop-hole at its extremity, a. In this loop-hole fix a pin a, with which describe the curve or involute, a b c de h, by unwrap- ping the thread gradually from the circumference A p m. The curve thus obtained will be the proper form for the teeth of a wheel whose diameter is A. B. It is a form which admits of several teeth acting together, a circumstance attended with the advantage of diminishing the pressure upon any one tooth, so much as to make the wheels wear longer and more equally ; and it possesses the merit of being more easily understood than the other methods directed to be observed. This last mode of forming the teeth of wheels is, however, only a modi- fication of the general principle, and indeed an involute is sometimes reckoned among the exterior epicycloids. The pro- priety of this will be allowed, when it is considered that the involute a b c d, &c., may be produced by an epicycloidal motion. Thus let on be a straight ruler, at whose extremity is fixed the pin m, and let the point of the pin be placed upon the point m of the circle; then by rolling the straight ruler upon the circular base, so that the point in which it touches the circle may move gradually from m towards B, the curve m n will be generated exactly similar to the involute a b c, &c. obtained by the string. Let the mechanic who wishes to have further directions for drawing epicycloids, take a piece of plain wood G. H., fig. 3, plate IV., and fix upon it another piece of wood E, having its circumference m b of the same curvature as the circular base up- on which the generating circle A B is to roll. When the gene- rating circle is large, the shaded segment B will be sufficient. In any part of the circumference of this segment, fix a sharp pointed steel pin a, which ought to be tempered, that it may easily make a distinct mark; and it must be driven in sloping, so that the distance of its point from the centre of the circle may be equally exact to its radius. Fasten to the board G. H., a piece of thin brass, or of tin-plate, a b. Place the segment B in such a position that the point of the steel pin a may be upon the point b, and roll the segment toward G, so that the nail a may rise gradually, and the point of contact between the two circular segments advance towards m ; the curve a b, described upon the brass plate, will be an accurate exterior epicycloid. Temove, with a file, the part of the brass on the left hand of the epicycloid, and the remaining concave a b will be a pattern tooth, by means of which all the rest may easily be formed. When an interior epicycloid is required, the generating circle must revolve upon a concave instead of a convex base, as in the present instance. The cycloid, which is useful in forming the teeth of rack-work, is generated in precisely the same manner, with this difference only, that the base on which the generating circle rolls must be a straight line. Perhaps no part of the mechanism of mill-work is executed with so little attention to theory as the teeth of wheels. Almost every millwright has his favourite construction, and it is seldom that the best methods are adopted. One of the many plans in ordinary use we shall here recite; from its being of tolerably easy application, and allowing much strength to the teeth, while it is somewhat free from friction in comparison with other practical methods. Let A B, fig. 4, plate IV., be two spur wheels of different diameters, of which the cogs are intended to work 66. into each other at half pitch. The dotted circular arcs G. H., E F, touching each other between s and d, are the centre or pitch lines, from which the teeth are formed. If the teeth of both wheels are iron, as is generally the case in the first mo- tions of work, those teeth are then made nearly both of a size at the pitch-line; but if the teeth of one be wood and the other iron, then the iron ones are made to have less pitch than the wooden ones, because they are then found to wear better. In the figure both are supposed to be of iron. Suppose the wheels to move from G toward H, and from E towards F, and that the sides of the teeth at b c, and d e, are in contact; from b as a centre, with a radius equal to bp, describe the arcs p d, lm ; $rom d as a centre with the same radius, describe the arcs h i, fºg, ch. Thus the same opening of the compasses, and a centre chosen where the wheels are in contact on the pitch lines, will mark the contour of the upper part of a tooth of one wheel, and the lower part of a corresponding tooth of the other wheel; and by taking several centres on the two pitch-lines, the various teeth may be formed. To prevent the cogs from bottoming, as the workmen call it, let the lower part, , e, of one tooth be made rather longer than the upper part p d, of the other which is to play into it. The way in which cogs thus constructed will work into one another, may be understood by considering the motion of two of them, n and o for example; when they first come into contact, they will appear as the curve a P 2 ; when they arrive at Q, the same sides will appear as in the dotted lines there represented ; and when the same arrive at R. S., they are in contact on other middle points. Of Wipers or Lifting Cogs.--It may be useful to notice here, that by means of notches called wipers, which project from the circumference of a wheel or axle, stampers, hammers, and other tools, are raised vertically and then suffered to fall. Fig. 5, plate IV., represents portions of a stamper for bruising ore, beating hemp, &c. and of its shaft with lifting cogs. G is the vertical arm of the stamper, sliding, when in actual work, between rollers, or in a groove, to keep it steadily in its proper position; a is the horizontal arm of the stamper; H part of the axle, on which the wipers or lifting cogs E F are fixed; the dotted lines at A, shew the height to which the horizontal arm a, of the stamper, is elevated by each wiper. A B is a line cor- responding with the arm of the stamper upon which the wipers first act; C D is the pitch-line of the axis, or the bottom of the curves of the wipers. The curved or acting faces of the wipers. are involutes of a circle equal in radius to the axis CD, and obtained as already described in noting its application to the formation of the teeth of wheels, viz. by unwrapping from the circumference of the circle alluded to, a thread or cord b, in the loop-hole, at the extremity of which is a pencil or marking point, describing the curve as it approaches towards c. The arm of the stamper is flat at the part where the wiper acts upon it, and should be placed in a line with the centre of the shaft or axis, at the time the first wiper comes into contact with it. Fig. 6, plate IV., exhibits the form of the wipers for a forge- hammer. The centre b, of the cylinder AB, in which the wipers are fixed, the flat part or tail-end of the hammer, where acted upon by the wipers, and the centre of the axis a of the hammer, must be in the same right line. The proper curve for the wipers is an exterior epicycloid ; formed by rolling upon the circum- ference of the circle at B, a circle of which the radius is equal to the distance from the centre of the axis a to the extremity of the tail of the hammer. Description of a common Corn Mill,—The water wheel A. B. fig. 7, plate IV., is generally from eighteen to twenty-four feetin diameter, reckoning from the outermost edge of any float-board at A, to that of the opposite one at B. The water striking on the floats of this wheel, drives it round, and gives motion to the mill. The wheel is fixed upon a very strong axis or shaft C, one end of which rests on D, and the other on E within the mill-house. On the shaft or axis C, and within the mill house, is a wheel F, about eight or nine feet in diameter, having cogs all round, which work in the upright staves or rounds of a trun- dle G. This trundle is fixed upon a strong iron axis, called the spindle, the lower end of which turns in a brass foot fixed at H, in a horizontal beam H., called the bridge-tree; and the upper end of the spindle turns in a wooden bush fixed into the nether mill-stone, which lies upon beams in the floor I. The 8 B . 646 M E C M E C DICTIONARY OF MECHANICAL SCIENCE. top of the spindle above the bush is square, and goes into a square hole in a strong iron cross, a b c d, fig. 8, called the rynd, under which, and close to the bush, is a round piece of thick leather upon the spindle which it turns round at the same time it does the rynd. The rynd is let into grooves in the under sur- face of the upper or running mill-stone, which it turns round in the same time that the trundle G is turned round by the cog- wheel F. This mill-stone has a large hole quite through its middle, called the eye of the stone, through which the middle part of the rynd and upper end of the spindle may be seen ; whilst the four ends of rynd lie below in their grooves. One end of the bridge-tree H, which supports the spindle, rests upon the wall, and the other end is let into a beam called the brayer, L. M. The brayer rests in a mortise at L, and the other end M, hangs by a strong iron rod N, which goes through the floor I, and has a screw and nut on its top at O; by the turning of this nut, the end M of the brayer is raised or de- pressed at pleasure, and consequently the bridge-tree and the upper mill-stone. By this means the upper mill-stone may be set as close to the under one, or raised as much above it, as may be necessary. It will of course be understood that the nearer the mill-stones are to each other, the finer the corn will be ground ; and that, on the contrary, the further they are sepa- rated, the coarser it will be. The upper mill-stone is enclosed in a round box, which mo where touches it, and is about an inch distant from its edge all round. On the top of this box stands a frame for holding the hopper P, to which is hung the shoe Q, by two lines fast- ened to the hinder part of it, fixed upon hooks in the hopper, and by one end of the string R fastened to the fore part of it, the other end being twisted round the pin, S. By turning this pin one way, the string draws up the shoe closer to the hopper, and so lessens the aperture between them : and as the pin is turned the other way, it lets down the shoe, and enlarges the aperture. If the shoe be drawn up quite to the hopper, no corn can fall from the hopper into the mill; if it be let down a little, some will fall; and the quantity will be more or less, according as the shoe is more or less let down; for the hopper is open at the bottom, and there is a hole at the bottom of the shoe, not directly under the bottom of the hopper, but nearer to the lowest end of the shoe, over the middle or eye of the Stone. - In a square hole at the top of the spindle, is put the feeder E, fig. 8. This feeder, as the spindle turns round, jogs the shoe three times in each revolution, and so causes the corn to run constantly down from the hopper through the shoe, into the eye of the mill-stone, where it falls upon the top of the rynd, and is, by the motion of the rynd, and the leather under it, thrown below the upper stone, and ground between it and the lower one. The rapid motion of the stone creates a cen- trifugal tendency in the corn going round with it, by which means it gets farther and farther from the centre, as in a spiral, in every revolution, until it is quite thrown out, and being then ground, it falls through a spout, called the mill-eye, into a trough placed for its reception.—When the mill is fed too fast, the corn bears up the stone, and it is ground too coarse ; be- sides, the mill is apt to get clogged, and to go too slowly. When the corn is scantily supplied, the mill goes too fast, and the stones by their collision are apt to strike fire. Both these in- conveniences are avoided, by turning the regulating pin, S, backward or forward, in order to draw up or let down the shoe, as the case is observed by the miller to require. g The heavier the running mill-stone, and the greater the quan- tity of water falling upon the wheel, the faster will the mill bear to be fed, and consequently the greater the performance of the mill. When the stone is considerably worn, and become light, its weight must either be increased by some artificial addition, or the mill must necessarily be fed slowly; otherwise the stone will be too much borne up by the corn under it, to grind the meal sufficiently fine. The power necessary to turn a heavy mill-stone, is but very little more than what is necessary to turn a light one ; for as the stone is supported upon the spindle of the bridge-tree, and the end of the spindle that turns in the brass foot is but small, the difference arising from the weight produces only an inconsiderable action against the power or force of the water. Besides, a heavy stone affords the same advantage as a heavy fly, that is, it regulates the motion much better than a light one, from its not being liable to such great fluctuations of velocity. - In order to cut and grind the corn, both the upper and under mill-stones have channels or furrows cut in them, proceeding obliquely from the centre to the circumference. These furrows, in the direction of their length, are cut slantwise on one side, and perpendicularly on the other, thus, [TNTN - so that each of the ridges which they form has a sharp edge ; and in the two stones, these edges pass one another like the edges of a pair of scissars, and so cut the corn, to make it grind the more easily, when it falls upon the furrows. The furrows are cut the same way in both stones, when they lie upon their backs, which makes them run crosswise to each other when the upper stone is inverted by turning its furrowed surface towards that of the lower, for, if the furrows of both stones lay the same way, part of the corn would be driven onward in the lower furrows, and come out from between the stones without being either ground or bruised. The grinding surface of the under stone is a little convex from the edge to the centre, and that of the upper stone a little concave; and they are farthest from one another in the middle, but approach gradually nearer towards the edges. By this means the corn, at its first entrance between the stones, is only bruised ; but as it goes farther on towards the circumference or edge, it is cut smaller and smaller, and, at last finely ground, just before it comes out from between them. When the ridges become blunt and the furrows shallow by wearing, the running stone must be taken up, and both of them may then be dressed anew with a chisel and mallet. Every time the stone is taken up, there must be some tallow put round the spindle and upon the bush; this unguent will soon be melted by the heat the spindle acquires from its turning and rubbing against the bush, which it will prevent from taking fire. The bush must embrace the spindle quite close, to prevent any shake in the motion, which would cause some parts of the stones to grate against each other, whilst the other parts of them would be too far asunder, and by that means spoil the meal. Hence, whenever the spindle has worn the bush, so as to begin to shake in it, the stone must be taken up, and a chisel driven into several parts of the bush; and when it is “taken out, wooden wedges must be forced into the holes; by which means the bush will be made closely to embrace the spindle again all round. In doing this, great care must be taken to drive equal wedges into the bush on opposite sides of the spindle: otherwise it will be thrown out of the perpendi- cular, and so hinder the upper stone from being set parallel to the under one, which is absolutely necessary for making good work. When any accident of this kind occurs, the perpendi- cular position of the spindle must be restored, by adjusting the bridge-tree with proper wedges put between it and the brayer. The rynd is sometimes wrenched in laying down the upper stone upon it, or is made to sink a little lower on one side of the spindle than on the other ; and this will cause one edge of the upper stone to drag all round upon the lower, while the op- posite edge will not touch. This is easily rectified, by raising the stone a little with a lever, and putting bits of paper, card, or thin chips, between the rynd and the stone. - Till the steam-engine came into general use, so as to make people independent of water and wind, and animal strength, as agents to drive machinery, the first-named was considered the best moving power; and wind the next, where water was denied ; and they are still used as valuable and powerful movers in many situations. To illustrate the combinations of machinery, any of these might be taken. We shall, for this purpose, confine ourselves at present to Water Mills. There are three descriptions of these, namely, Breast-mills, Undershot-mills, and Overshot-mills, according to the manner in which the water is applied to the great wheel. In the first, the water falls down upon the wheel at right angles to the float-boards or buckets placed all round the wheel to receive it. In the second, which is used where there is no fall but a considerable body of water, the stream strikes the float-boards at the lower part of the wheel. In the third, the water is poured over the top, and is received in buckets formed all round the wheel. According to Smeaton, | s § | | _º|| |- || || | | | - - º T TM E C M. E. C .647 DICTIONARY OF MECHANICAL SCIENCE, the power necessary to produce the same effect on the under- shot-wheel, a breast-wheel, and an overshot wheel, must be to each other as the numbers 2-4, l'75, and 1. Rules for the Construction of Water-Mills :-}. Measure the perpendicular height of the fall of water, in feet, above that part of the wheel on which the water begins to act, and call that the height of the fall. 2. Multiply this constant num- ber 64:2822 by the height of the fall in feet, and the square root of the product will be the velocity of the water at the bottom of the fall, or the number of feet that the water there moves per second. 3. Divide the velocity of the water by three, and the quotient will be the velocity of the float-boards of the wheel, or the number of feet they must each go through in a second, when the water acts upon them so as to have the greatest power to turn the mill. 4. Divide the circumference of the wheel in feet by the velocity of its floats in feet per second, and the quotient will be the number of seconds in which the wheel turns round. 5. By this last number of seconds divide 60, and the quotient will be the number of turns of the wheel in a minute. 6. Divide 120 (the number of revolutions a millstone four feet and a half in diameter ought to have in a minute) by the number of turns of the wheel in a minute, and the quotient will be the number of turns the mill- stone ought to have, for one turn of the wheel. 7. Then, as the number of turns of the wheel in a minute is to the number of turns of the millstone in a minute, so must the number of staves in the trundle be to the number of cogs in the wheel, in the nearest whole numbers that can be found. The breadth of the water-wheel ought to correspond with the power necessary on the occasion, supposing that a propor- tionate volume of water is at command; for a wheel of two feet in breadth will be more than double as powerful as one only a foot broad, there being a double volume of water acting upon it, while the friction of the axis is by no means doubled with this augmentation of breadth. . It may be well to notice here Smeaton's discovery, that “the , more slowly any body descends by the force of gravity while acting upon any piece of machinery, the more of that force will be spent upon it, and consequently the effect will be the greater.” That effect is not increased in proportion to the velocity of the wheel’s motion. Smeaton found, that when the wheel with which he experimented (two feet in diameter) revolved 20 times in a minute, its effect was greatest; when it made only 18% turns, the effect was irregular; and when so laden as not to make 18 turns, the wheel was overpowered by the load : thirty turns in the minute occasioned a loss of about one-twentieth ; and when turned above 30 times in a minute, the diminution of effect was nearly one-fourth of its powers. This proportion may be easily estimated on any wheel of greater extent, by computing the proportion of accumulated power lost by greater velocity than may be suffi- cient to load the wheel by means of the buckets being filled; observing, that the progress of a machine may be so much re- tarded as to cause the effect to be irrelevant to the purpose, although the machine may be kept in motion. To compute the effects of water-wheels, ascertain, 1. The real velocity of the water which acts upon the wheel; 2. the quan- tity of water expended in a given time; and 3. how much of the power is lost by friction. Smeaton found that the mean power of a volume of water 15 inches in height, gave 8.96 feet of velocity in each minute to a wheel on which it impinged. The computation of the power to produce such an effect, allow- ing the head of water to be 105.8 inches, gave 264.7 pounds of water descending in one minute through the space of 15 inches, therefore 2647, multiplied by 15, was equal to 3-970. But as that power will raise no more than 9:375 pounds to the height. of 135 inches, it was manifest that the major part of the power was lost; for the multiplication of these two sums only amount- ed to 1.266; of course the friction was equal to three-fourths of the power. According to Smeaton, this is the maximum single effect of water upon an undershot-wheel, where the fall is fifteen inches. The remainder, of power, it is plain, must equal that of the velocity of the wheel itself, multiplied into the weight of the water, which in this case brings the true propor- tion between the power and the effect to be as 3,849 to 1266, Or as 11 to 4. In Undershot mills, the float-boards should be rather nume- rous than few. Smeaton found when he reduced them from 24 to 12, that the effect was reduced one-half, because the water escaped between the floats without touching them; but when he added a circular sweep of such length, that before one float board quitted it, another had entered it, he found the former effect nearly restored. This mode more particularly applies to breast wheels, or such as receive the water immediately below the level of the axis. In such, the float boards should be confined both at their sides and at their extremities, so that the water may accompany them all the way from the head down to the lowest part of the wheel, whence it should pass off with suffi- cient readiness to allow the succeeding fall to supply its place, without being in the least retarded. It has been ascertained, that a very sensible advantage is gained by inclining the float- boards to the radius of the wheel, so that each float-board, when lowest, shall have its edge turned up the stream about twenty degrees. - The Overshot wheel is the most powerful, giving a result equal to four-fifths of the power. The Breast wheel, well constructed, yields a half or 3-5ths of the power. But often, from inattention to the reduction of friction, and inaccurate workmanship, the power not only of this, but of the preceding forms also, is greatly reduced. The teeth of wheels ought not to act upon each other before they arrive at the line which joins their centres; and though the inner or under side of the teeth may be of any form, yet it is better to make both sides alike, that the wheels may admit. of being revolved either way with equal facility. The teeth should be made as fine as the case admits, so that the greatest number possible may be in contact at once ; and the utmost care should be taken to have them so regularly disposed that they may not interfere with each other before they begin to work ; and they should be so formed that the pressure by which one of them urges the other round its axis, may be constantly the same. This is by no means the case, when the common construction of a spur wheel, acting in the cylindrical staves of a lantern or trundle, is used. The ends of teeth should never be formed of parts of circles, unless working with other teeth, specifically adapted to them. - - Method of Setting out Wheels.—For a Spur-wheel and Trundle, Lantern or Wallower, draw the pitch lines A 1, B 1, A2, B2, fig. 1, plate III., then divide the number of teeth or cogs required, as a b c. Divide one of these distances, as b c, into 7 equal parts, as 1, 2, 3, 4, 5, 6, 7: allow 3 for the thickness of the cogs, as 1, 2, 3, in the cog a ; and 4 for the diameter of the stave of the trundle, as 1, 2, 3, 4, in the stave m, fig. 2. Three parts are allowed for the cog, and 4 for the stave, the wallower being supposed to be of less diameter than the wheel, therefore subject to more wear, in proportion as the number of cogs exceed the number of staves; but if in any case the number of staves and cogs be the same, they may be of equal thickness. The height of the cog is equal to 4 parts; then divide its height into 5 equal parts, as 1, 2, 3, 4, 5 in the cog c ; allow 3 for the bottom to the pitch line of the cog ; the other 2 for the curve which must be given it, to make it fit and bear on the stave equally. - - In common practice, the millwrights are accustomed to put the point of a pair of compasses in the dot 3 of the cog a, and strike the line df; then they remove the point of the compasses to the point d, and strike the curve 3 e, by which means they obtain a curve which they consider sufficiently correct. For a face-wheel, divide the pitch-line A B, fig. 2, into the number of cogs intended, as a b c ; divide the distance b c into 7 equal parts; allow 3 of these for the thickness of the cogs, as 1, 2, 3, in the cog a, 4 for the height, and 4 for the width, as de, and 4 for the thickness of the stave m. Draw a line through the centre of the cog, as the line A 1, at S; and on the point 5 describe the line de; remove the compasses to the point A, and draw the line fg, by which the shape of the cog will be determined. . . . For common spur nuts, divide the pitch-line, A, fig. 3, into twice as many equal parts as there are intended to be teeth, as a, b, c, d, e ; with a pair of compasses open to half the diš- tance of any of these divisions, from the points a 1, c 3, e 5, draw the semicircles a, e, and e, which will form the ends of the 648 M E C M E D DICTIONARY OF MECHANICAL SCIENCE. teeth. From the points 2, 4, and 6, draw the semicircles g, h, i, which will form the lower parts of the spaces. Though spur- nuts are usually set out in this manner, yet in good work, the ends of the teeth must not be semicircles, unless working with other teeth adapted to them, but epicycloids. Of Bevel Geer.—Bevelled wheels, commonly called bevel- geer, which have nearly superseded the spur wheels and trun- dles, are, in effect, truncated cones, rolling on the surface of each other. Suppose the cones A and B, revolving on their centres a p, a c, fig. 4, plate III, ; if their bases are equal, they will perform their revolutions in equal times, and consequently any two points equally distant from the centre a of A, as a b, a c, a d, a e, will revolve in the same time as a f, a g, a h, a i. If one of the cones, as in fig. 5, be twice the diameter of the other, the base of the larger will make one revolution, while that of the smaller will make two ; and all the corresponding parts of the conical surfaces will observe the same proportion; that is, a b, a c, a d, a e, will turn only once round, while a f, a 9, a h, a i, turn twice round; the number of the revolutions of all cones revolving in this manner, being to each other as their respective diameters. Let two cones have teeth cut in them, as represented by fig. 6; they will become bevel-geer. These teeth would be broadest at the base, from whence they would gradually taper with the lessening circumference of the come, till they terminated at the apex a in a point; but as such an extent of teeth would be unnecessary, the useless parts of the teeth are cut off, as at E and F; that is, bevel-geer is composed of wheels made in the form of truncated cones, as shewn by fig. 7, where the upright shaft A B, with the bevel-wheel CD, turns the bevel-wheel E F, with its shaft G. H., and the teeth work freely in each other. The method of conveying motion in any direction, and of proportioning or shaping the wheels accordingly, is as follows: let the line a b, fig. 8, plate III. represent the shaft coming from a wheel ; draw the line c d to intersect the line a b in the direc- tion intended for the motion to be conveyed, and this line c d will represent the shaft of the bevel-wheel which is to receive the motion. Suppose then the shaft c d is to revolve three times, whilst the shaft a b revolves once; draw the parallel line i i at any moderate distance, (suppose one foot by a scale,) then draw the parallel line k k, at three feet distance, after which draw the dotted line war, through the intersection of the shaft a b and c d, and likewise through the intersection of the parallel lines i i and k h, in the points a, and y, which will be the pitch-line of the two bevel-wheels, or the line where the teeth of the two wheels act on each other, as may be seen by fig. 9, where it is obvious to inspection that the motion may be conveyed in any direction. In crown wheels and bevelled geer, the faces of the teeth must be all tapered, as if they proceeded from a common centre. The pinion may be considered as a portion of a come, which, rolling along the horizontal rim of the wheel, traces the contour of the teeth, by describing a modified epicycloid. The same general principles indicate all the variations. It is of practical consequence that the teeth of wheels should all be equally worn. In their mutual congress, therefore, they ought to produce a series of the most diversified contacts. To effect this object, the number of teeth in the pinion and the wheel must be as discordant as possible. If the one were any aliquot part of the other, the same incessant coincidence would soon recur, occasioning a partial and disproportionate attrition. Prime numbers should be preferred, and the larger they are, the smoother will the wheels work. The odd tooth in the pinion is by our mill-wrights very appositely called the hunt- 2ng cog. - - The effects produced by machines are extremely diversified. To extend action to a distance, or to divert its direction, to reduce or multiply the celerity impressed; to modify an uni- form progression into an accelerating or retarding one ; to maintain a parallel motion; to change a rectilineal into a cir- cular motion, and the reverse; to convert a reciprocating play into a constant circulation or equable rectilineal flow;-these are a few of the objects generally aimed at. Pressure is con- veyed to any distance, by a system of parallel levers, sup- ported at certain intervals, the extremities of their arms being connected by a train of beams. The direction of any power is | easily changed, by means of a crank or bent lever. The same contrivance, aided by the action of a fly, converts a recipro- cating into a circular motion. This effect is likewise produced by a rack, working alternately on the opposite sides of a toothed wheel. The celerity is modified at pleasure, by affixing to the axle solid blocks, sometimes called heart wheels, and fashioned like spiral or eccentric curves. These lines may be traced with such accuracy as to evolve the precise succession of im- pulse required. But all the transitions should, if possible, be gradual, any sudden change occasioning a concussion which wastes the force, and tends to disjoint and shatter the parts of the machine. The most elegant mode of transmitting force in any direc- tion, is by a contrivance termed the Universal Joint, (see the Plate, fig. 10.) Instead of the cross, a ring or a ball is often preferred. But the angular motion communicated in this way is not quite equable, and becomes even irregular in the case of great obliquity. By doubling, however, the combination of axes, the impression may be turned aside almost into an op- posite direction, and may be rendered uniform by a compen- sation of irregularities. An alternate motion is beautifully converted into a revolving one, by a vertical rod which carries affixed to it a wheel in- dented to another wheel of the same size. The central wheel, describing at each reciprocation a double circumference, must turn twice round. This mechanism is, from a vague analogy, called the Sun and Planet Wheel. A reciprocating beam can be made to raise and depress a rod very nearly in a vertical line, by means of a regulated parallelogram. Thus, asin the figure, C being the centre of the beam, let an arm B E turn about the \ T} B O- J-T-f § firm joint B, and guide the end E of the parallelogram A DEF; if C D be taken a mean proportional to A D and B E, the other end F, carrying the rod of a piston, will travel in a path which is very nearly rectilineal and perpendicular. These two fine contrivances were happily combined in Watt's Steam Engine. MechANICAL Surgery, is a branch of the profession, the object of which is, by mechanical means, to relieve or to remedy certain deformities or injuries to which some persons are subject from their birth, but which in many cases are the result of accident. MEDAL denotes a piece of metal in the form of coin, such as was either current money among the ancients, or struck on any particular occasion, to preserve the portrait of some great person, or the memory of some illustrious action, to posterity. As historical documents, they form the principal evidence we can have of the truth of the old historians. In some few in- stances they correct the names of sovereigns; and in a great many, illustrate the chronology of reigns. By their assistance the geographer has sometimes been enabled to determine the situation of a town whose name alone has reached us. To the naturalist they afford the only proofs of the knowledge which the ancients had of certain plants and animals; and they some- times preserve delineations of buildings for the architect, of which not even a ruin is at this day standing. MEDALLION, or MedALIon, a medal of an extraordinary size, supposed to be anciently struck by the emperors for their friends, and for foreign princes and ambassadors. But, that the smallness of their number might not endanger the loss of the devices they bore, the Romans generally took care to stamp the subject of them upon their ordinary coin. Medal- lions, in respect of the other coins, were the same as modern medals in respect of modern money: they were exempted from all commerce, and had no other value than what was set upon them by the fancy of the owner. Medallions are so scarce, that there cannot be any set made of them, even though the metals and sizes should be mixed promiscuously. MEDEOLA, Climbing African Asparagus, a genus of plants .A. M E D M E D ' DICTIONARY OF MECHANICAL SCIENCE. 649 belonging to the hexandria class, and in the natural method ranking under the 11th order, sarmentaceae. MEDIANA, the name of a vein or little vessel, made by the union of the cephalic and basilic in the bend of the elbow. MEDIASTINUM, in Anatomy, a double membrane, formed by a duplicature of the pleura; serving to divide the thorax and the lungs into two parts, and to sustain the viscera, and prevent their falling from one side of the thorax to the other. See ANATO MY. NMEDIATE, or INTERMediAte, something that stands betwixt and connects two or more terms considered as extremes; in which sense it stands opposed to immediate. MEDIATOR, a person that manages or transacts between two parties at variance, in order to reconcile them. . The word, in scripture, is applied, 1. To Jesus Christ, who is the only intercessor and peace-maker between God and man, (1 Tim. ji, 5.) 2. To Moses, who interposed between the Lord and his people, to declare unto them his word, (Deut. v. 5., iii. 19.) MEDICAGO FALCATA. Yellow Medic.—Is nearly allied to lucerne, and is equally good for fodder; it will grow on land that is very dry, and hence is likely to become a most use- ful plant; its culture has, however, been tried but partially. Some experiments were made with this plant by Thomas Le Blanc, Esq., in Suffolk, which are recorded by Professor Martyn. Medic A Go PolyMorph A. Variable Medic.—This is also a plant much relished by cattle, but is not in cultivation: it is an annual, and perhaps inferior in many respects to the Non- such, which it in some measure resembles. There are many varieties of this plant cultivated in flower gardens on account of the curious shapes of the seed-pods, some having a distant resenblance to snails’ horns, caterpillars, &c. under which names they are sold in the seed-shops. It grows in Sandy hilly soils; the wild kind has flat pods. Medica Go SATIva. Lucerne.—Too much cannot be said in praise of this most useful perennial plant: it is every thing the farmer can wish for, excepting that it will not grow without proper culture. It should be drilled at eighteen inches dis- tance, and kept constantly hoed all summer, have a large coat of manure in winter, and be dug intô the ground between the drills. Six or seven pounds of seed will sow an acre in this mode. Lucerne is sometimes sown with grass and clover for forming meadow land; but as it does not thrive well when en- cumbered with other plants, no good can be derived from the practice. No plant requires, or in fact deserves, better culti- vation than this, and few plants yield less if badly managed. Medic AGo LUPULINA. Trefoil, or Nonsuch.-A biennial plant, very usefully cultivated with rye-grass and clover for forming artificial meadows. Trefoil when left on the ground will seed, and these will readily grow and renew the plant suc- cessively; which has caused some persons to suppose it to be perennial. About eight or ten pounds of seed are usually sown with six or eight pecks of rye-grass for an acre, under a crop of barley or oats. - MEDICAGo, Snail Trefoil, a genus of plants belonging to the diadelphia class, and in the natural method ranking under the 32d order, papilionaceae. See Green's Botanical Dictionary. For the properties and culture of Lucerne, a species of this genus, see AGRICULTURE. MEDICINAL, any thing belonging to medicine. Medic1 NAL Springs, a general name for any fountain, the waters of which are of use for removing certain disorders. They are commonly either chalybeate or sulphureous. See SPRINGS and WATER. MEDICINE, the art of preventing, curing, or alleviating those diseases to which the human body is subject, is of very great antiquity, for we find that the sacred historian styles those servants to Joseph, who embalmed the body of the patri- arch Jacob, “physicians.” Joseph was then in Egypt, the cradle of science, where Hioth, the inventor of the art, shared divine honours with Osiris and Isis. Esculapius was the most eminent practitioner among the Greeks, and the writings of Hippocrates are the most ancient on this art, since they were penned 400 years before Christ. This sage judged of diseases from the look, posture of the patient in bed, from respiration, the excrementitious discharges, expectoration, sweat, and the 67. pulse. His maxims for the preservation of health are, tem- perance, exercise, and labour. His maxims for the cure of diseases are, that evacuations cure those diseases which come from repletion, and repletion those caused by evacuations. The first physician, of eminence who differed considerably in his practice from Hippocrates was Praxagoras. Coelius Aure- lianus acquaints us, that he made great use of vomits in his practice, insomuch as to exhibit them in the iliac passion till the excrements were discharged by the mouth. In this distem- per he also advised, when all other methods failed, to open the belly, cut the intestine, take out the indurated faeces, and then to sew up all again ; but this practice has not probably been followed by any subsequent physician. This man had for a disciple the famous Herophilus, who was contemporary with Erasistratus, a physician of great eminence, who flourished in §: time of Seleucus, one of the successors of Alexander the reat. Celsus, who lived in the time of Tiberius, ranks next to Hippocrates as a medical writer and physician. Galen, a native of Pergamus, made a great figure as a writer and prac- titioner in this art during the reign of Adrian. Time would fail us to name all the useful and empiric physicians who flourished from that period till the downſall of the Roman empire, when the inundation of Goths and Vandals had almost completely exterminated literature of every kind in Europe, and medicine, though a practical art, shared the same fate with more abstract sciences. Learning in general; banished from the seat of arms, took refuge among the eastern nations, where the arts of peace still continued to be cultivated. To the Arabian physicians, as they have been called, we are indebted both for the preservation of medical science, as it subsisted among the Greeks and Romans, and likewise for the description of some new diseases, particularly the small-pox. Among the most eminent of the Arabians, we may mention Rhases, Avicenna, Albucasis, and Avenzoar. But of their writings it would be tedious, and is unnecessary, to give any particular account. They were for the most part, indeed, only copiers of the Greeks. We are, however, indebted to them for some improvements. They were the first who introduced chemical remedies, though of these they used but few, nor did they make any considerable progress in the chemical art. Anatomy was not in the least improved by them, nor did surgery receive any advancement till the time of Albucasis, who lived probably in the 12th century. They added a great deal to botany and the materia medica, by the introduction of new drugs, of the aromatic kind especially, from the East, many of which are of considerable use. They also found out the way of making sugar; and by help of that, syrups; which two new materials are of great use in mixing up compound medicines. s In the beginning of the 16th century, the famous chemist Paracelsus introduced a new system into medicine, founded on the principles of chemistry. The Galenical system had pre- vailed till his time; but the practice had greatly degenerated, and was become quite trifling and frivolous. The physicians in general rejected the use of opium, mercury, and other effica- cious remedies. Paracelsus, who made use of them, had therefore greatly the advantage over them; and now all things relating to medicine were explained on imaginary chemical principles. It will easily be conceived, that a practice founded in this manner could be no other than the most dangerous quackery. The discovery of the circulation of the blood in the year 1528, opened a new era in medicine, which the abilities of Stahl, Hoffman, Boerhaave, Cullen, and Dr. James Gregory, ...have further extended. Medicine, in examining the functions of the human body, considers those that relate to itself only, and others to external things. To the latter class belong those which, by physicians, are called the animal functions; to which are to be referred all our senses, as well as the power of voluntary motion, by which we become acquainted with the universe, and enjoy this earth. Among the functions which relate to the body, some have been named vital, such as the circulation of the blood and respira- tion; because, without the constant continuance of these, life cannot subsist; others, intended for repairing the waste of the system, have been termed the natural functions; for by the 8 C 650 M E D M. F. D DICTIONARY | OF MECHANICAL SCIENCE. constant attrition of the solids and the evaporation of the fluid parts of the body, we stand in need of nourishment to supply the waste; after which the putrid and excrementitious parts must be thrown out by the proper passages. The digestion of the food, secretion of the humours, and excretion of the putrid parts of the food, are referred to this class; which, though necessary to life, may yet be interrupted for a considerable time without danger. This division of the functions into ani- mal, vital, and natural, is of very ancient date, and is perhaps one of the best that has yet been proposed. Distinction of Diseases into Simple and Compound. A disease takes place when the body has sofar declined from a sound state, that its functions are either quite impeded, or performed with difficulty. A disease therefore may happen to any part of the body either solid or fluid, or to any one of the functions; and those may occur either singly, or several of them may be diseased at the same time; whence the distinction of diseases into simple and compound. We have examples of the most simple kinds of diseases, in the rupture or other injury of any of the corporeal organs, by which means they become less fit for performing their offices; or, though the organs themselves should remain sound, if the solids or fluids have degenerated from a healthy state; or if, having lost their proper qualities, they have acquired others of a different, perhaps of a noxious nature; or, lastly, if the moving powers shall become too weak or too strong, or direct their force in a way contrary to what nature requires. tº e iº . * Symptoms. The most simple diseases are either productive of others, or of symptoms, by which alone they become known to us. Everything in which a sick person is observed to differ from one in health is called a symptom; and the most remark- able of these symptoms, which most commonly appear, define and constituté the disease. e Predisponen: Cause. The causes of diseases are various; often obscure, and sometimes totally unknown. The most full and perfect proximate cause is that which, when present, produces a disease; when taken away, removes it; and when changed, changes it.—There are also remote causes, which physicians have been accustomed to divide into the predispo- ment and exciting ones. The former are those which only render the body fit for a disease, or which put it into such a state that it will readily receive one. The exciting cause is that which immediately produces the disease in a body already disposed to receive it. • º Exciting Cause. The predisponent cause is always inherent in the body itself, though perhaps it originally came from with- out; thus heat or cold, a very sparing or a very luxurious diet, and many other particulars, may operate as causes of predis- position, inducing plethora, inanition, or the like: but the exciting cause may either come from within or without. Proacimate Cause. From the combined action of the predis- ponent and exciting causes comes the proximate cause, which neither of the two taken singly is often able to produce. A body predisposed to disease therefore has already declined somewhat from a state of perfect health, although none of its functions are impeded in such a manner that we can truly say the person is diseased. Yet sometimes the predisponent cause, by continuing long, may arrive at such a height, that it alone, without the addition of any exciting cause, may produce a real disease. The exciting cause also, though it should not be able immediately to bring on a disease; yet if it continues long, will by degrees, destroy the strongest consitution, and render it liable to various diseases; because it either produces a predisponent cause, or is converted into it, so that the same thing may sometimes be an exciting cause, sometimes a pre- disponent one, or rather a cause of predisposition; of which the inclemencies of the weather, sloth, luxury, &c. are examples. Hereditary Diseases. Diseases, however, seem to have their origin from the very constitution of the animal machine; and hence many diseases are common to every body when a proper exciting cause occurs, though some people are much more . liable to certain diseases than others. Some are hereditary; for as healthy parents naturally produce healthy children, so diseased parents as naturally produce, a diseased offspring. Some of these diseases appear in the earliest infancy; others gccur equally at all ages; nor are there wanting some which lurk unsuspected even to the latest old age, at last breaking out with the utmost violence Some diseases are born with us, even though they have no proper foundation in our consti- tution, as when a foetus receives some hurt by an injury done to the mother; while others, neither born with us, nor having any foundation in the constitution, are suckled in with the nurse’s milk. * Diseases from Age and Sea. Many diseases accompany the different stages of life; and hence some are proper to infancy, youth, and old age. Some also are proper to each of the sexes; especially the female sex, proceeding, no doubt, from the general constitution of the body, but particularly from the state of the parts subservient to generation. Hence the diseases peculiar to virgins, to menstruating women, to women with child, to lying-in women, to nurses, and to old women. Diseases from Climate. The climate itself, under which people live, produces some diseases; and every climate has a tendency to produce particular diseases, either from its excess of heat or cold, or from the mutability of the weather. An immense number of diseases also may be produced by impure air, or such as is loaded with putrid, marshy, and other noxious vapours. The same thing may happen likewise from cor- rupted aliment, whether meat or drink; though even the best and most nutritious aliment will hurt if taken in too great quan- tity; not to mention poisons, which are endowed with such pernicious qualities, that even when taken in a very small quantity they produce the most grievous diseases, or perhaps even death itself. Lastly, from innumerable accidents and dangers to which mankind are exposed, they frequently come off with broken limbs, wounds, and contusions, sometimes quite incurable; and these misfortunes, though proceeding from an external cause, often terminate in internal diseases. Diseases from Passions of the Mind. Besides the dangers arising from those actions of the body and mind which are in our own power, there are others arising from those which are quite involuntary. Thus, passions of the mind, either when carried to too great excess, or when long continued, equally destroy the health; nay, will even sometimes bring on sudden death. Sleep also, which is of the greatest service in restoring the exhausted strength of the body, proves noxious either from its too great or too little quantity. In the most healthy body also, many things always require to be evacuated. The reten- tion of these is hurtful, as well as too profuse an evacuation, or the excretion of those things either spontaneously or arti- ficially, which nature directs to be retained. As the solid parts sometimes become flabby, soft, almost dissolved, and unfit for their proper offices; so the fluids are sometimes inspissated, and formed even into the hardest solid masses. Hence im- peded action of the organs, vehement pain, various and grievous diseases. Lastly, some animals are to be reckoned among the causes of diseases; such, particularly, as support their life at the expense of others; and these either invade us from without, or take up their residence within the body, gnawing the bowels while the person is yet alive, with great danger and distress. It would be foreign to our purpose to enter upon any analysis of the animal solids, their qualities, &c.; nor can we do more than enumerate the vital solids, or those which enjoy sense and mobility, as feeling, pain, anxiety, itching, taste, smell, hearing, sight, vertigo; memory, delirium, melancholy, and idiotism, which four last are properly internal senses. The disorders in the muscular power arise from too great mobility, vigour, torpor, debility, palsy, spasm; — sleep, the circulation of the blood, the pulsation of the arteries, palpita- tion, syncope, are all different disorders from the former; and diseases of the blood arise from plethora, inanition, morbid thinness, thickness, and acrimony;-the disorders of respira- tion are, coughs and sneezings; those of digestion embrace costiveness and looseness; such as proceed from the disorgani- zation of the alimentary canal, are, dysentery, tenesmus, nausea, iliac passion, vomiting, cholera ; from disorders in the secretory organs proceed excessive perspiration, suppression of urine, dysuria, strangury, urinary calculi, and scirrhus. MEDIETAS LINGUAE, a jury or inquest, whereof the one half consists of denizens, the other strangers, in pleas, wherein the one party is a stranger. M. E. L. M E N 651 DICTIONARY OF MECHANICAL SCIENCE. MEDIUM, in Logic, the mean or middle term of a syllogism, being an argument, reason, or consideration for which we affirm or deny any thing: or, it is the cause why the greater extreme is affirmed or denied of the less, in the conclusion. - MeDIUM, in Arithmetic, or Arithmetical Medium or Mean, that which is equally distant from each extreme, or which ex- ceeds the lesser extreme as much as it is exceeded by the greater, in respect of quantity, not of proportion; thus, 9 is a medium between 6 and 12. - .* MEDIUM, Geometrical, is that where the same ratio is preserv- ed between the first and second, as between the second and third terms, or that which exceeds the same ratio, or quota of itself, as it is exceeded : thus, 6 is a geometrical medium be- tween 4 and 9. MeDIUM, in Philosophy, that space or region through which a body in motion passes to any point: thus, asther is supposed to be the medium through which the heavenly bodies move. MeDIUM, Subtile or Æthereal. Sir Isaac Newton makes it probable, that besides the particular aerial medium, wherein we live and breathe, there is another more universal one, which he calls an aethereal medium, vastly more rare, subtile, elastic, and active than air, and by that means freely permeating the pores and interstices of all other mediums, and diffusing itself through the whole creation ; and by the intervention hereof, he thinks it is, that most of the great phenomena of nature are effected. | MEDUSA, in Natural History, a genus of the vermes mol- lusca class and order. They consist of a tender gelatinous mass of different figure, with arms proceeding from the lower surface : the larger species, when touched, cause a slight ting- ling and redness, and are usually denominated sea-nettles; they are supposed to constitute the chief food of cetaceous fish. Most of them shine with great splendour in the water. MELANCHOLY, a species of insanity, supposed to arise from a redundancy of bile, which from disease becomes of a dark colour. See MEDICINE. MELASIC ACID, found in molasses, supposed to be the same as the acetic acid. MELEAGRIS, in Natural History, the turkey, a genus of birds of the order gallinae. The wild turkey is a native of America, the presumed origin of every species under the genus. In the northern parts of that continent these birds are found in flocks of several hundreds, which during the day-time resort to the woods, feeding principally upon acorns, returning by night to some swampy grounds, where they roost upon the high- est trees. In Carolina they occasionally grow to the weight of thirty pounds. Turkeys breed only once in a year, but will produce a great number at a time, sometimes seventeen. The female sits with extreme closeness, and is very assiduous in. maternal duties. The young, however, are very susceptible of injury, from almost innumerable causes, from cold and wet, and even sunshine itself. . MELISSA OFFICINALIS. Balm.—This herb, in its recent state, has a weak, roughish, aromatic taste, and a pleasant smell, somewhat of the lemon kind. On distilling the fresh herb with water, it impregnates the first runnings pretty strongly with its grateful flavour. Prepared as tea, however, it makes a grateful diluent drink in fevers; and in this way it is commonly used, either by itself, or acidulated with the juice of lemons. MELITTIS MELISSOPHYLLUM, and Melittis GRANDI- FLORA. Bastard Balm.—Both these plants are very beautiful, and are deserving a place in the flower garden: they are of easy culture, and will grow well under the shade of trees, a property that will always recommend them to the notice of the curious. MELLATES, in Chemistry, a genus of salts formed from the mellitic acid. MELLITE, or Honey Stone, in Mineralogy, takes its name from its yellow colour like that of honey. Its primitive figure is an octahedron. The crystals are small, their surface is com- monly smooth and shining. Internally it is splendent. It is transparent, passing into the opaque, and possesses a double refraction. It is softer than amber, and brittle. Specific gra- vity is from about 1.5 to 1-7. It becomes electric by friction, but continues so only a short time. This mineral occurs on bituminous wood, an earthy coal, and is commonly accompanied with sulphur. - \ , MELLITIC ACID, is procured from mellite reduced to pow- der, and boiled with about seventy-two times its weight of water, the alumina is precipitated in the form of flakes, and the acid combines with the water. By filtration and evaporation, crystals are deposited in the form of fine needles, or in small short prisms. The acid is not very soluble in water; its con- stituent parts are carbon, hydrogen, and oxygen. In combina- tion with the earths, alkalies, and metallic oxides, it forms compounds denominated mellates. MELODRAME. See DRAMA. A modern word for dramatic performances in which songs are intermixed. MELODY, in Music, the agreeable effect of different sounds, ranged and disposed in succession, so that melody is the effect of a single voice or instrument, by which it is distinguished from harmony. MELOE, a genus of insects of the order coleoptera. Thirty- five species have been described. The oil beetle, entirely blue- black or dark violet, is found in the advanced state of spring, in fields and pastures, creeping slowly, the body appearing so distended with eggs as to cause the insect to move with difficulty. On being roughly touched, it suddeuly exudes a moisture from the pores, of a yellow colour, and of a very penetrating and peculiar smell. The female of this spe- cies deposits her eggs in a heap beneath the surface of the ground; from these are hatched the larvae, which find subsist- ence by attaching themselves to other insects, and absorbing their juices. The blister-fly, or Spanish-fly, found chiefly in Spain, is an insect of great beauty, being entirely of the richest gilded grass green, with black antennae. This is the cantharis of the shops, and the safest and most efficacious application for a blister plaster. * MENDICANTS, several orders of friars, who having no set- tled revenue, are supported by charitable contributions. MENISCUS, a little moon, or rather a half-moon. A glass, concave on one side and convex on the other; as a watch lass. MENISPERMIC ACID, supposed to be found in the me- mispermum cocculus. MENNONITES, a sect who believe that the New Testament is the only rule of faith; that the terms person and trinity are not to be used when speaking of the Father, Son, and Holy Ghost; that the first man was not created perfect; that it is un- | lawful to swear or to wage war upon any occasion; that infants are not the proper subjects of baptism; and that ministers of the gospel ought to receive no salary. - MENSTRUUM, Solvent or Dissolvent, any fluid that pos- sesses the property of dissolving or separating the parts of solid bodies. MENSURABILITY, capacity of being measured. MENSURATION, that branch of Mathematics which treats of the measurement of the extensions, capacities, solidities, &c. of bodies; and which, in consequence of its very extensive applications to the various purposes of life, may be justly con- sidered as one of the most important of mathematical sciences. It is highly probable, that this science in its more simple state may be traced to the origin of human society. When men began to multiply, and turn their attention to the cultivation of the earth, it became necessary to have some means of dis- tinguishing the portions belonging to each individual or family, both as to situation and quantity. The same necessity dictated some means for enumerating their flocks and herds. Hence, the former gave rise to mensuration, and the latter to arith- metic. But although the invention of mensuration cannot be attributed to any one person or nation, its existence may be traced to Egypt at a very early age, where, though in its in- fancy, it assumed a scientific form, immediately connected with the overflowing of the Nile. After the Egyptians, the Greeks embodied this science into something like a regular system, and to them we are indebted for its elementary principles. In some of its kindred departments, Euclid, Archimedes, and Cavalerius have gained immortality; and until this science shall be lost, the names of Bonnycastle and Hutton cannot be forgotten. It is not consistent with the plan of this work to enter into details, but the clearness, simplicity, and rationality 652 M E R M. E. N DICTIONARY OF MECHANICAL SCIENCE. t of its simple principles, may be gathered from the following observations:—Every quantity is measured by some other quantity of the same kind; as a line by a line, a surface by a surface, and a solid by a solid; and the number which shews how often the lesser, called the measuring unit, is contained in the greater, or quantity measured, is called the content of the quantity so measured. Thus, if the quantity to be measured be the rectangle A B C D, and the little C - D square E, whose side is one inch, be the measuring unit, then, as often as the said little square is contained in the rectangle, so many square inches the rectangle is said to contain: so that if the length D C be supposed 5 inches, and the breadth A. A D 3 inches, the content of the rectangle will be 3 times 5, or 15 square inches: because, if lines be drawn parallel to the sides, at an inch distance one from another, they will divide B |E| the whole rectangle A B C D into 3 times 5, or 15 equal parts, of one inch each. And, generally, whatever the measures of the two sides may be, it is evident that the rectangle will con- tain the square E, as many times as the base A B contains the base of the square, repeated as often as the altitude A D con- tains the altitude of the square. Hence we have the following rule for any parallelogram whatever:—To find the area of a parallelogram, whether it be a square, a rectangle, a rhombus, or a rhomboides. Multiply the length by the perpendicular height, and the product will be the area. MENTHA VIRIDIS. Spear-mint.—The virtues of mint are those of a warm stomachic and carminative: in loss of appe- tite, nausea, continual retchings to vomit, and (as Boerhaave expresses it) almost paralytic weaknesses of the stomach, there are few simples perhaps of equal efficacy. In colicky pains, the gripes to which children are subject, lienteries, and other kinds of immoderate fluxes, this plant frequently does good service. It likewise proves beneficial in sundry hysteric cases, and affords an useful cordial in languors and other weaknesses consequent upon delivery. The best preparations for these purposes are, a strong infusion made frem the dry leaves in water (which is much superior to one from the green herb) or rather a tincture or extract prepared with rectified spirit. The essential oil, a simple and spirituous water, and a conserve, are kept in the shops: the Edinburgh College directs an infu- sion of the leaves in the distilled water. This herb is an ingre- dient also in the three alexiterial waters; and its essential oil, in the stomach plaster and stomachic pills. MENTHA PIPERITA. Pepper-mint.—The leaves have a more penetrating smell than any of the other mints, and a much warmer, pungent, glowing taste like pepper, sinking as it were into the tongue. The principal use of this herb is in flatulent colics, languors, and other like disorders; it seems to aet as soon as taken, and extends its effects through the whole sys- tem, instantly communicating a glowing warmth. Water extracts the whole of the pungency of this herb by infusion, and elevates it in distillation. an essential oil, and a simple and spirituous water. MENTHA PULEGIUM. Pennyroyal.—Pennyroyal is a warm pungent herb of the aromatic kind, similar to mint, but more acrid and less agreeable. It has long been held in great esteem, and not undeservedly, as an aperient and deobstruent, particularly in hysteric complaints, and suppressions of the uterine purgations. For these purposes, the distilled water is generally made use of, or, what is of equal efficacy, an infusion of the leaves. It is observable, that both water and rectified spirit extract the virtues of this herb by infusion, and likewise elevate greatest part of them in distillation. MENYANTHES TRIFQLIATA. Buck-bean.—The leaves of this plant yield an efficacious aperient and deobstruent; it promotes the fluid secretions, and, if liberally taken, gently loosens the belly. It has of late gained great reputation in scorbutic and scrofulous disorders; and its good effects in these cases have been warranted by experience : inveterate cutaneous diseases have been removed by an infusion of the leaves, drunk to the quantity of a pintº a day, at proper inter- vals, and continued some weeks. Boerhaave relates, that he was relieved of the gout by drinking the juice mixed with whey. Its officinal preparations are distillation with quick-lime or iron filings. dily unite with sulphur. MeNYANthes NYMPHoides. Round-leaved Bog Bean—This is a beautiful aquatic, and claims a place in all ornamental pieces of water. . . . . - MERCATOR, GerARD, an eminent geographer and mathe- matician, was born in the Low Countries in 1512; to whom we are indebted for the construction of those sea-charts called after him Mercator’s charts, as also for that part of navigation which is after him called Mercator sailing. He died at Duis- bourg in 1594. - - MeRCAtoR, Nicholas, a celebrated mathematician and astro- nomer, was born at Holstein in 1640; but spent all the latter part of his life in England, and was admitted a fellow of the Royal Society. He is said to have possessed considerable talents, but was not of a very liberal turn of mind. Having made himself master of the analogy between a scale of loga- rithmic tangents and Wright's protraction of the nautical meri- dial line, which consisted of the sums of the secants, though it did not appear by whom this analogy was first discovered, and being desirous of making the most advantage of this and another invention in navigation, he, by a paper in the Phil. Trans. for June, 1666, invited the public to enter into a wager with him on his ability to prove the truth or falsehood of the supposed analogy . This proposal, not very reputable to a man of science and literature, was not taken up by any one, and Mercator reserved his demonstration; he however distin- guished himself by many valuable pieces on philosophy and mathematical subjects. He died at the age of 55, in the year 1694. - MERCHANT, a person who buys and sells commodities in gross, or deals in exchanges ; or that traffics in the way of com- merce, either by importation or exportation. - MERCURIALIS ANNUA. Annual Dog's Mercury.—Per- sons who are in the habit of gathering wild herbs to cook, should be careful of this. It gróws plentifully in all rich grounds, and is common with fat-hen and the other herbs usually collected for such purposes in the spring, and from which it is not readily distinguished: at least, we cannot de- scribe a difference that a person, ignorant of botany, can dis- tinguish it by. • - MERCURY, is a metal, which in our climate is always fluid, but in intense cold it becomes solid, and then resembles silver in appearance, and is malleable.—It is sometimes found native, but much more frequently combined with sulphur, when it is denominated cinnabar. It is separated from the sulphur by Mercury is obtained abundantly in the Austrian territories, and in South America. Mercury has a great affinity to other metals. Dip a shilling in mercury, it will be encrusted over, and will require to be rub- bed very much before the mercury is got off. The same cir- cumstance will occur if any other metal be put in mercury. Rub some quicksilver and tinfoil together, and they will unite into one mass. Such a composition is called an amalgam. Mercury and lead will also combine. If lead, bismuth, and mercury, are united together, the amalgam will be equally fluid with the simple mercury itself.-From this circumstance, disho- nourable dealers frequently impose on the public this impure composition, and, when the metal is to be used medically, dan- gerous consequences are the result. Mercury is used in baro- meters, thermometers, in silvering looking-glasses, and form- ing amalgams for gilding and silvering metals: also in the making of vermilion. In countries where there are gold and silver mines, it is employed in separating the precious metals from extraneous matter. Mercury is nearly fourteen times the weight of water, and is the heaviest of all metals after gold and platinum. In consequence of its great weight, if a piece of stone, iron, lead, or silver, be put in a cup of mercury, it will float in the same manner, and for exactly the same reason, as a piece of wood in water. Mercury is readily soluble in acids, as may easily be ascertained, and from its very extensive use in medicine, there are innumerable preparations of it, by which it may be exhibited in powders, pills, or drops to the patient. The most usual is calomel, which is a preparation of mercury and muriatic acid. One preparation of mercury, named cor- rosive sublimate, is a most deadly poison. Mercury will rea- Melt some sulphur in a crucible on the fire, and then add a little mercury, and stir the whole toge- M E. R. M E R 653 DICTIONARY OF MECHANICAL SCIENCE. ther, and a sulphuret of mercury, or cinnabar, will be formed. Vermilion is a beautiful scarlet pigment, prepared from mer- cury and sulphur, and is called by chemists the red sulphuret- ted oxide of mercury. The property of mercury dissolving a certain portion of gold and silver, enabled alchymists to impose upon mankind, and make it appear as if they had succeeded in a small degree in discovering the secret of turning metals into gold and silver. In their operations they employed mercury, in which small portions of these metals had been dissolved ; and as the mercury was evaporated by great heat, and left the gold and silver behind, the bystanders were made to believe that these metals had actually been produced in operation by the skill of the experimentalist. Calomel is now called, in the momenclature of the day, the protochloride of mercury, and cor- rosive sublimate is called the deutochloride. Mercury freezes at 390 below Zero, and boils at 656°Fahrenheit.—Mercury being habitually fluid, very readily, combines with most of the metals, to which it communicates more or less of its fusibility. When these metallic mixtures contain a sufficient quantity of mercury to render them soft at a mean temperature, they are called amalgams. It very readily combines with gold, silver, lead, tin, bismuth, and zinc ; more difficultly with copper, arsenic, and antimony; and scarcely at all with platina or iron. Look- ing-glasses are covered on the back surface with an amalgam of tin. Some of the uses of mercury have already been men- tioned in the present article. The amalgamation of the noble metals, water-gildings, the making of vermilion, the silvering of looking-glasses, the making of barometers and thermome- ters, and the preparation of several powerful medicines, are the principal uses to which the metal is applied.—Scarcely any substance is so liable to adulteration as mercury, owing to the property which it possesses of dissolving completely some of the baser metals. This union is so strong, that they even rise along with the quicksilver when distilled. The impurity of mercury is generally indicated by its dull aspect; by its tar- nishing, and becoming covered with a coat of oxide, on long exposure to the air; by its adhesion to the surface of glass ; and when shaken with water in a bottle, by the speedy forma- tion of a black powder. Lead and tin are frequently impurities, and the mercury becomes capable of taking up more of these if zinc or bismuth be previously added. Meltoury, in Astronomy, is the nearest planet to the sun, denoted by the character § : its mean distance being 387, that of the earth being considered as unity; which makes that dis- tance above 36 millions of miles. He performs his sidereal revolution in 87d 23h 15'43"'9, and his mean synodical revolu- tion in about 116 days. The eccentricity of his orbit is 2055; half the major axis being taken equal to unity. His mean longitude, at the commencement of the present century, was in 5s 3° 56' 27"-0. The longitude of his perihelion was, at the same time, in 25 14° 21'46"-9; but the line of the apsides has a sidereal motion, according to the order of the signs, equal to 9'43".6 in a century. Which motion, if referred to the ecliptic, will (owing to the precession of the equinoctial points) be equal to 55".8 in a year; or to 1933'13"-6 in a century. The orbit of Mercury is inclined to the plane of the ecliptic in an angle of 7°0'9":1; but this angle is subject to a small increase of about 18"–2 in a century. His orbit, at the commencement of the pre- sent century, crossed the ecliptic in 1° 15°57', 30".9: having a sidereal motion to the westward every century, of 13'2"-2; but if referred to the ecliptic, the place of the modes will (on account of the precession of the equinoxes) fall more to the eastward by 42"-3 in a year, or 1910. 27".8 in a century. The rotation on his axis is accomplished in 16 Oh 5'28":3, but the inclination of its axis is not known. The diameter of Mercury is about 3123 miles: which, compared with the earth’s diameter considered as unity, is about 3944; his apparent diameter being 6'-9. His mass, compared with that of the sun considered as unity, is soºrs, and the proportion of light and heat received from the Sun is about 6'68 times greater than on our planet. As seen from the earth, Mercury never appears at any great distance from the sun; either in the morning or the evening; his clon- gation, or angular distance, varying only from 16°12' to 28°48'. See ASTRONOMY. His course sometimes appears retrograde, the mean arc, which it describes in this case, being about *3°30'; and its mean duration is about 23 days; but there is 67. great difference in this respect. This retrogradation com- mences or finishes when he is about 18° distant from the sum. Mercury changes his phases, like the moon, according to his various positions with regard to the earth and sun: but this cannot be discovered without the aid of a telescope. This planet is sometimes seen to pass over the sun's disc: which can only happen when he is in his nodes, and when the earth is in the same longitude; consequently this phenomenon can take place only in the month of May or November. The first obser- vation of this kind was made by Gassendi, in November 1631: º glish period they have been frequent; the last occurred in 1822. - MERCURY, in the science of Heraldry, a term used in blazon- ing by planets, for the purple colour used in the arms of sove- reign princes. - . - MERGER, in Law, is where a less estate in lands, &c. is drowned in the greater. - MERGUS, in Ornithology, a genus of birds of the order an- seres. There are ten species: M. merganser, the goosander, weighs about four pounds, and is twenty-eight inches long. It is common in the northern regions of Europe and Asia, and is found in the Orkneys during the whole year. It builds gene- rally in the holes and fissures of rocks, and feeds on fish. Its flesh is strong, and seldom used for food. The smew is about 18 inches long, the head is adorned with a long crest, white above and black beneath, the tail of a deep ash-colour. The legs bluish gray; the rest of the body white. . The red-breasted goosander, considerably less than the former, is found also in the same latitudes, and breeds in the north of Scotland. It dives excellently, and is extremely alert on the water. These birds, like the other species of the genus, subsist in a great degree on fish. They fly near the surface of the water with great vigour, and their bills are admirably adapted to secure their prey. ~ . MERIDIAN, in Astronomy, (from the Latin meridies, mid- day,) is a great circle of the celestial sphere, passing through the poles of the world and zenith and nadir, crossing the equa- tor at right angles, and dividing the sphere into an eastern and western hemisphere. When the sun is south of this circle it is noon, or mid-day, to all places situated under that meri- dian, whence the derivation of the word as above stated. MERIDIAN, in Geography, a corresponding terrestrial circle in the plane of the former, and which therefore passes through the poles of the earth. All places situated under the same meridian have their noon or midnight at the same time; but under different meridians, it will arrive sooner or later, accord- ing as they are situated to the eastward or westward of each other, viz. the Sun will be upon that meridian soonest which is most to the eastward, and that at the rate of an hour for every 15 degrees. - - First MERIDIAN, is that from which all the others are reck- oned, which being totally arbitrary, has been variously chosen by different geographers. Ptolemy makes his first meridian pass through the most western of the Canary Islands, others have chosen Cape Verd, some the Peak of Teneriffe, others the island of Fero, &c.; but most nations now consider that the first meridian which passes over their metropolis, or their principal observatory. Thus the English reckon from the meridian of London, or rather of Greenwich ; the French from that of Paris; the Spanish from Madrid, &c. MERIDIAN of a Globe, is the brazen circle in which it turns, and by which it is supported. - The Brazen MERIDIAN, is divided into 360 equal parts, called degrees. In the upper semicircle of the brass meridian these degrees are numbered from 0 to 90, or from the equator towards the poles, and are used for finding the latitudes of places. On the lower semicircle of the brass meridian they are numbered from 0 to 90; from the poles towards the equa- tor, and are used in the elevation of the poles. MeRIDIAN Line, is a north and south line, the exact deter- mination of which is of the greatest importance in all cases relating to astronomy, geography, dialling, &c. because on this all the other parts have their dependence. The most cele- brated meridian line is that on the pavement of the church of St. Petronio in Bologna, which was drawn to the length of one hundred and twenty feet by the celebrated Cassini, 8 D 654 M E R M E T' DICTIONARY OF MECHANICAL SCIENCE. To Draw a Meridian Line.—Know- ing the south quarter pretty nearly, observe the altitude FIB of some star . on the eastern side thereof, not far". from the meridian HZ R N ; then keeping the quadrant firm on its axis, so as the plummet may still cut the same degree, only directing it to the western side of the meridian, wait till you find the star has the same altitude as before f, e. Lastly, bisect the angle Ee, formed by the intersection of the two planes wherein the quadrant is placed at the time of the two observations, by the right line H. R. This H R is a meridian line. Or thus: On the horizontal plane, from the same centre C, describe several arcs of circles B.A., b a and e, and on the same centre C erect a stile, or gnomon, perpendicular to the plane A C B, a foot or half a foot long. About the 21st of June, between the E hours of nine and eleven in the morning, and between one and three in the afternoon, observe the points B, b, &c. A., a, wherein the shadow of the stile terminates. Bisect the B arcs A B, a b, &c. in D, d, &c. If • * > - then the same right line D.E. bisect all the arcs AB, a b, &c, it will be the meridian line sought. As it is difficult to determine A. the extremity of the shadow exactly, it is best to have thc | stile flat at top, and to drill a little hole, noting the lucid spot projected by it on the arcs A B, and a b, instead of the extre- mity of the shadow. Otherwise, the circles may be made with yellow, instead of black, &c. Several authors have invented particular instruments and methods for the describing of meridian lines, or rather for determining equal altitudes of the sun in the eastern and western parts of the heavens; but as the former of the methods above delivered suffices for astrono- mical observations, and the latter for more ordinary occasions, we shall omit giving any descriptions of them. MeRIDIAN Line, on a dial, is the same as the 12 o'clock hour line. Meridian Line, on the Gunter’s scale, is a line divided unequally towards 87°, corresponding to the meridian in Mercator’s chart. Magnetic MeRIDIAN, a great circle passing through the magnetic poles. - MeRIDIAN Altitude, the altitude of any of the heavenly bodies when they are upon the meridian. MERIDIONAL DISTANCE, in Navigation, is of the same import as DEPARTURE, or distance between the meridians of two places. - MeRIDIONAL Parts, Miles, or Minutes, in Navigation, are the parts of the increased meridians according to the Mercator chart. The parts of the enlarged meridians in the Mercator chart increase in proportion to the cosines of the latitudes to radius, or as the radius to the secants, or since the radius is constant, they increase simply as the secants; and therefore the whole enlarged meridian for any parallel of latitude will be proportional to the sum of all the secants to that place, which, for common purposes, are found near enough by adding toge- ther the secants of every angle in minutes; that is, the meridional parts for 1' = sec. 1" - for 2" = sec. 1' + sec. 2'. for 3" E sec. 1' + sec. 2' + sec. 3'. &c. C. and this way they were first computed by Wright. But it is obvi- ous, that this is merely an approximation, and at the same time attended with considerable labour; other methods have there- fore been invented for this purpose by Bond, Gregory, Halley, Robertson, &c. See the latter author's Treatise on Navigation, vol. ii. book 8. But if the earth be considered as a spheroid, the method of computation is a little more varied, though it is attended with the same accuracy as in the former case. See Dr. Jamieson's Treatise on the Construction of Maps. MERLIN. See FALCO. * , , MEROPS, a genus of birds of the order picae. Gmelin no- tices twenty-six species, and Latham twenty. The common bee-eater, is about ten inches long, and found in many countries of Europe, though never observed in Great Britain. It is par- ticularly fond of bees, but will eat various other insects; many of which it seizes, like the swallow, on the wing. When insects .." difficulty to be found, it feeds on many species of SCCC. S. - - MESNE, he who is lord of a manor, and has tenants holding of him, yet himself holds of a superior lord. - ; MESNE Process, an intermediate process which issues pend- ing the suit, upon some collateral interlocutory matter. Some- times it is put in contradistinction to final process, or process of execution ; and then it signifies all, such process as inter- venes between the beginning and end of a suit. -- -- MESPILUS, in Botany, a genus of the icosandria pentagynia class and order.—Natural order of pomaceae. There are nine species. The Dutch or common medlar never rises with an upright trunk, but sends out crooked deformed branches, not far from the ground; leaves large, entire, downy, on their under side : flowers very large, as also the fruit, which ap- proaches to the shape of an apple. This tree, bearing the larg— est fruit, is now generally cultivated: the Nottingham medlar has a more poignant taste, but the fruit is considerably less. MESSENGERS, are certain officers chiefly employed under the direction of the secretaries of state, and always in readiness to be sent with all kinds of despatches, foreign and domestic. They also, by virtue of the secretaries' warrants, take up per- : sons for high treason, or other offences against the state. METALLURGY, comprehends the whole art of working metals, from the state of ore to the utensil; hence, assaying, gilding, refining, smelting, &c. are only branches of metallurgy. In a more limited sense, it includes only the operations which are followed in separating metals from their ores. METALS. Gold occurs in a metallic state, alloyed with a little silver or copper, in the mines of Germany, Hungary, and America, in veins, and disseminated in granite, gneiss, por- phyry, and schist; in flakes, massive, and in grains, of a yel- low colour, shining, opake, and of a metallic lustre. Pure gold, chemically obtained, is of a deep yellow colour; it melts at a bright red heat, and, in fusion, appears of a brilliant green; and it forms compounds with most of the gaseous and simple combinations. Silver occurs in nature pure, and alloyed with gold, anti- mony, arsenic, and bismuth. Common native silver occurs in veins, in the middle or upper parts when traversing granite, gneiss, mica slate, and porphyry, in primitive mountains; and wacke, in transition ores in Cornwall, Saxony, Hungary, and Mexico; in crystals, massive, and in leaves; of a whitish splendent metallic lustre, and opake. Auriferous native silver, containing a portion of gold, was formerly found in the mines . of Konigsberg, in Norway, and at present in those of Schlan- genberg in Siberia. It melts at a cherry-red heat, in fusion is very brilliant, and is not oxidized by exposure to air. - Platinum is found in small grains and rolled pieces, in allu- vial soil, along with gold, silver, osmium, iridium, zirconium, and quartz, in New Grenada and Brazil, of a steel gray colour and shining lustre. This substance is dissolved in nitro-muriatic acid, then precipitated by a solution of muriate of ammonia; this is repeated, and the second precipitate heated while hot, leaves pure platinum, a white metal very difficult of fusion, and unaltered by the joint action of heat and air. Palladium, Rhodium, Iridium, and Osmium, have much re- semblance in lustre, and all are obtained from crude platinum; but only the first is malleable. . - Mercury occurs rarely in primitive and transition rocks; more frequently in those of the coal formation; in Deux Ponts, Idria, and other European mining districts. The principal ore is native cinnabar, whence the mercury is chemically sepa- rated. It is a brilliant tin-white metal, with a blue tint, opake, splendent, and metallic; liquid at all common temperatures.’ Copper is found native, and in various states of combination. It occurs in crystals, and massive, in granite, gneiss, mica. slate, clay slate, primitive limestone, and serpentine ; often in small veins, also in grains, and sometimes in blocks many pounds weight, in alluvial districts; in serpentine in Shetland, M ET 655 Diction ARY of MECHANICAL science. M E \' . \ and in the Cornish copper mines, Large masses occur in the [ northern part of North America. It has a fine red colour, much brilliancy, is very malleable and ductile, has a peculiar || smell when warmed or rubbed, and melts at a cherry-red or dull white heat. - t Tellurium occurs in wacke in Transylvania, and also in Tellemark in Norway, granular, massive, and disseminated, of a tin-white colour, shining metallic lustre, rather brittle, and easily frangible, fusible, and very volatile. - Iron is of a blue-white colour, very malleable and ductile, and fusible at a white heat. The most important native com- binations, whence are drawn the immense supplies for the arts of life, are the oxides. ral acids; also some vegetable and animal bodies, and is so abundant that few fossils are devoid of it. The different ores are found often in thick beds in the primitive rocks, gneiss, hornblende slate, granite, &c. less in transition rocks, in veins, beds, and masses in porphyry. - - Tin has a silvery-white colour, is malleable, but sparingly ductile; it is obtained by heating red with charcoal the native ore, which in all its varieties occurs in granite, gneiss, por- phyry, and alluvial deposits, in the Cornish mines, in crystals, and concretions, of various colours, splendent, adamantine lus- tre ; semitransparent to opake. Zinc is a blueish-white metal, malleable, but very brittle about the point of fusion, (680°;) the ore occurs in New Jersey and Sussex, North America, of a red colour, massive, trans- lucent, and opakc. The oxide occurs in veins of galena, and clay slate, and in beds in masses, in the mines of Flint and Leicestershires; in crystals, and concretions, dull lustre, opake; when the metal is red, it inflames, burns bright, and is converted into a white tasteless flocculent substance, soluble in alcalies, and called philosopher’s wool. Manganese is of a blueish-white colour, very brittle, and difficult of fusion; and becomes an oxide when exposed to the air. The ore is found native in great abundance, in veins in primitive rocks; in crystals and concretions of a grayish-black colour, massive, glimmering, opake. Maganese of a brown and red colour occurs at Kapuic, in Transylvania, and at Cathe- rineberg, in Siberia; and in Sweden, in beds of magnetic iron ore, in gneiss, manganese spar occurs massive, of a bright rose- red colour. - º: Potassium is a white metal of great lustre; (obtained by decomposing, by the action of iron at a white heat, the sub- stance called caustic potash,) on exposure to air it instantly tarnishes; it is dućtile, and of the consistency of soft wax; when cold it is hard and brittle; it easily fuses; heated in air, it burns with a brilliant white flame, and at bright red heat rises in vapour. Sodium (obtained from soda by a method analogous to that for obtaining potassium) in colour resembles lead, easily fuses, is volatile at a white heat, burns when heated in contact with air, and thrown on water produces violent action, but the metal does not often inflame. Bariumis obtained from an amalgam of the earth baryta and mercury negatively electrized; and the mercury then expelled by heat, leaves the metal, of a dark gray colour, more than twice the weight of water; it greedily absorbs oxygen, and gently heated burns with a deep red light. Lead occurs in galena veins at Leadhills, Wanlockhead, and the Paris mine in Anglesea, in crystals, granular and mas- sive, of a blueish-white colour mostly, adamantine lustre, from splendent to shining, and translucent; and convertible into an oxide by the united action of heat and air. Nickel occurs native in Scotland, at Leadhills, and Wanlock- head, and in the Coal-field of West Lothian; it occurs in silver and cobalt veins in gneiss, mica slate, clay slate, and sienite; also in bituminous marl slate, granular, massive ; brittle, cop- pery-red, shining, and metallic lustre. Arsenic exists in nature nearly pure, in the mines of Ger- many, Norway, Russia, and France, and frequently occurs, combined with other metallic substances, in metalliferous veins, where they cross each other, in gneiss, mica slate, clay slate, and porphyry, massive, in plates, of a tin-white colour, soon tarnishing; glistening metallic Justre; it is very inflammable, fusible, and volatile; and highly poisonous. " . - It is combined with sulphur, and seve- | Molybdenum is of a whitish-gray colour, and with extreme difficulty fused. # * i g Chrome ore occurs in veins and beds in serpentine and trap,' in Scotland and Shetland, in crystals and granular, grayish, shining, and opake; the metal is white, brittlé, and of very. difficult fusion. + - - Tungsten is a native tung state of lime, and Wolfram is the same of tungstic acid, iron, and manganese. They occur in Cornwall, sometimes in crystals, granular, massive; of a white, brown, and yellow colour, shining and splendent, resinous, ºtent the metals in colour resemble iron, are hard and brittle, . Columbium was first discovered by Mr. Hatchett in a mineral from North America. Little is yet known of its properties. Strontian is procured from the earth strontia, by the same process as Barium; which metal it much resembles; but it is not poisonous. Uranium. The oxide of sulphuret occurs native in the mines of Cornwall, in crystals, green, spkendent, and trans- lucent; hence the metal is obtained of a gray colour, and with difficulty fused. ' *. Cerium is obtained from a mineral named Cesite, which occurs in a bed of copper at Ridderhyttan, in Sweden. - Cobalt is of a gray colour, brittle, and difficult of fusion, ob- tained by a very complex process from the ores, which occur at various places in Norway, Sweden, and Britain. - Bismuth is a brittle, brilliant white metal, with a slight tint of red; not easily fused, and on cooling always crystallizes; is affected by heat and air. With gold, platinum, and tin, it forms brittle compounds. . . . Calcium is a white metal, obtained (like Barium,) from lime; which, exposed to air, and gently heated, burns in a whitish flame. Of numerous new minerals we select the following from Dr. Brewster's Edinburgh Journal of Science for 1825: * Roselite, a new mineral, of a deep red rose colour, contains water, oxide of cobalt, lime, arsenic acid, and magnesia. - Columbite, from America, contains 30 per cent. of man- ganese. - - * Brochantile, of an emerald green colour, is met with in mas- sive red copper, from the Bank mine, Ekatherineburg, Siberia, Fluellite, compounded of alumina and fluoric acid, is whitish and prismatic. • Torrelite, from America, is composed of silica, lime, and iron. Hyalosiderite, a new mineral, occurs in small crystals, some- times imperfectly formed, in a basaltic amygdaloid of a reddish- brown colour, at Breisgaw, in Germany. This is a species of volcanic iron glass ; magnetic if gently heated, and fusible in a high temperature. Specific gravity = 2.875. Hopeite, a new mineral, prismatic in form, grayish-white in colour, and translucent. Specific gravity = 2.76. It is soluble in acids, without effervescence. It is found near Aix-la- Chapelle. - Childrenite, a new mineral, whose hardness is so great that it scratches glass, and is found near Tavistock in Devonshire, on the surface of quartz. Its constituent parts are iron and alumina, and it resembles in appearance sparry iron ore and heavy spar. - Somervillite, a new mineral, of a pale yellow, hard and fusi- ble into greenish globules. It is found about Vesuvius. Nuttalite, a new mineral, found imbedded in calcareous spar, soft, and glassy in its fracture. Of American origin. Babingtonite, a new mineral, brilliant, black, scratches glass, and is composed of iron, silica, and manganese. Sillimanite, a new mineral, occurs crystalized, dark-gray colour, brilliant upon the single face of clearage, harder than topaz, brittle and easily reduced to powder; specific gravity – 3:410. It is met with in Connecticut. º • Baryto-Calcite, a new mineral, of a grayish tinge ; specific gravity = 3-66; it consists of carbonate of barytes and car- bonate of lime, with traces of iron and manganese. ... . METAMORPHOSIS, the change of a person or thing into another form. Most of the ancient metamorphoses include some allegorical meaning, relating either to physics or morality, Some authors are of opinion, that a great part of the ancient philosophy is couched under them. 656. M E t M E T DICTIONARY OF MECHANICAL SCIENCE. METAPHOR, the application of a word to a use to which in its original import it cannot be put, as “he bridles his anger,” “the golden harvest.” METAPHYSICS, the science which considers beings as abstracted from all matter, particularly beings purely spiritual, as God, angels, the human soul; or it may be defined, the science of the principles and causes of all things existing. Hence it is, that mind or intelligence, and especially the supreme intelligence, which is the cause of the universe, and of every thing which it contains, is the principal subject of this science. The word originated with Aristotle, who has termed a treatise which chiefly relates to the intellectual world, and which is placed after his physics, (see PHYSICs,) META. TA Phusis. So that it may mean either something “beyond phy- sics,” or merely “an appendix to physics,” or natural history. METEMPSYCHOSIS, from meta, again, em, in, and pswche, the soul. Transmigration, or the supposed passage of the soul from one body to another. Pythagoras and his followers believed that after death men's souls passed into other bodies, of this or that kind, according to the manner of life they had led. If they had been vicious, they were imprisoned in the bodies of miserable beasts, there to do penance for several ages, at the expiration whereof they returned afresh to ani- mate men. But if they lived virtuously, some happier brute, or even a human creature, was to be their lot. supposed to have borrowed this from the ancient Brachmans, (certain inhabitants of India.) The notion still makes the prin- cipal foundation of their religion. Many not only forbear eat- ing any thing which has life, but even refuse to defend them- selves from wild beasts. - i METEOR. This term is by some writers made to compre- hend all the visible phenomena of meteorology, but it is more generally confined to luminous bodies, appearing suddenly at uncertain times, and with more or less of motion in the atmo- sphere. These may be reduced under three classes, viz. ſire balls, falling or shooting stars, and ignes fatui. In tropical climates these meteors are more common and more stupendous than in these more temperate regions. But they sometimes also visit the more genial regions of Europe. Two of them appeared in England in the year 1783, the first of them was seen on the 18th of August, and was, in appearance, a luminous hall, which rose in the N. N. W. nearly round; it however soon became elliptical, and gradually assumed a tail as it as- cended, and in a certain part of its course, seemed to burst, after which it proceeded no longer as an entire mass, but was apparently divided into a cluster of balls of different magni- tudes, and all carrying or leaving a train behind, till having passed the east, and verging considerably to the south, it gra- dually descended, and was lost out of sight. The time of its appearance was about sixteen minutes past nine in the evening, and it was visible about half a minute. It was seen in all parts of Great Britain, at Paris, at Nuits, in Burgundy, and even at Rome; and is supposed to have described a tract of 1000 miles at least over the surface of the earth. The illumi- nation of these meteors is often so great as to totally obliterate the stars, to make the moon look dull, and even to aſſect the spectators like the sun itself. The body of the fire ball, even before it bursts, did not appear of a uniform brightness, but consisted of lucid and dull parts, which were constantly chang- ing their respective positions, so that the whole effect was like an internal agitation or boiling of the matter. Its height seems to have varied from 55 to 60 miles. A report was heard some time after the meteor disappeared, and this report was loudest in Lincolnshire and the adjacent parts, and again in the eastern parts of Kent. Judging from the height of the meteor, its bulk is conjectured to have been not less than half a mile in diame- ter; and when we consider this bulk, its velocity cannot fail to astonish us, which is supposed to be at the rate of more than 40 miles in a second. - - Dr. Blagden is of opinion, that the general cause of these phenomena is electricity; but we cannot subscribe to this opi- nion. The duration of the fire-ball, the unequal consistency of the mass, and several other points in the narration, seem to indicate that its materials were of a less rare and evanescent mature than the electric fire. . . " . . . The shooting or falling star is a common phenomenon; but Pythagoras is | though so frequently observed, the great distance and tran- sient nature of these meteors have hitherto frustrated every attempt to ascertain, their cause. The connexion of these with an active state of the atmospheric electricity, is, however, cer- tain from observation; and we have more reason to consider . them as electric scintillae than as solid or fluid matter in the act of combustion. They precede a change of wind. Concern- ing the nature and composition of the ignis fatuus, or will-with a-wisp, there is less dispute, the generality of philosophers being agreed, that it is caused by some volatile vapour of the phosphoric kind, probably the phosphorized hydrogen gas. The light from putrescent substances, particularly putrid fish, and those sparks emitted from the sea or sea water when agi- tated, in the dark, correspond in appearance with this meteor. METEORIC STONEs. See AEROLITEs. METEOROLOGY, the application of natural philosophy to the constant or variable phenomena going on in the mass of the atmosphere, or at the surface of the earth, by the general action of natural agents, such as heat, electricity, and magnetism. In it are comprehended the unequal distribution of heat upon the earth, the laws of its variations in the different seasons of the year, the decrease of density, and the falling of the temperature of the atmospheric strata at different heights, winds, clouds, fogs, rain, snow, hail, thunder, and water-spouts. The leading facts respecting Meteorology are summed up by Mr. Daniels in the following propositions.—1. The mean height of the barometer at the level of the sea is the same in every part of the globe. 2. The barometer constantly descends in a geometrical progression, for equal ascents in the atmosphere subject to a correction for the decreasing temperature of the elevation. 3. The mean temperature of the earth's surface increases gradually from the poles to the equator. 4. The mean temperature of the atmosphere decreases from below upwards in a regular gradation. The fact is sufficiently established by numerous observations. Mr. Dalton was the first to demon- strate the natural equilibrium of heat in an atmosphere, is when an atom of air, in the same perpendicular column, is possessed of the same quantity of heat, and consequently that an equili- brium results when the temperature gradually diminishes in ascending. This is the natural consequence of the increased capacity for heat derived from rarefaction; when the quantity of heat is limited, the temperature must be regulated by the density. . * - . 5. The barometer at the level of the sea is but very slightly affected by the annual or diurnal fluctuations of temperature. 6. The barometer in the higher regions of the atmosphere is greatly affected by the annual or diurnal fluctuations of tem- perature. This observation is easily confirmed in various ways, but it is sufficient to refer for its correctness to those valuable registers which are simultaneously kept at Geneva, and the summit of Mount St. Bernard. 7. The heating and cooling of the atmosphere by the changes of day and night take place equally throughout its mass. This is fully established by the same series of observations. 8. The average quantity of vapour in the atmosphere decreases from below upwards, and from the equator to the poles. This con- sequence is obviously derivable from the preceding laws of temperature, and is moreover amply confirmed by experiment. 9. The condensation of elastic vapour into cloud raises the temperature of the air. In confirmation of this theoretical and practical conclusion, the observation of M. de Luc may be adduced. - 3. 10. Another remarkable phenomenon is, that there exists a general tendency in the wind to blow from north to east, and south-east towards the equator in latitudes below 30°. 11.While the trade wind blows upon the surface of the earth, a current flows in the contrary direction at a great clevation in the atmo- sphere. This necessary consequence of the theory of the trade winds, rested for a long time upon theoretical conclusions only; the eruption, however, of the volcano in the island of St. Vin- cent, in the year 1812, placed the fact beyond dispute. The island of Barbadoes is situated considerably to the east of St. Vincent, and between the two the trade wind continually blows, and with such force that it is with considerable difficulty and only by making a very long circuit, that a ship can sail from the latter to the former ; notwithstanding this, during the erup: M E 'T M E T 657 DICTIONARY OF MECHANICAL SCIENCE. tion at St. Vincent, dense clouds were formed at a great height in the atmosphere above Barbadoes, and a vast profusion of ashes fell upon the island. This apparent transportation of matter against the wind caused the utmost astonishment amongst the inhabitants, and the certainty of the fact cannot but be considered as of the utmost interest to the science of mete- orology. -- - 12. The mean height of the barometer is not affected by the trade winds. This is a proof that the quantity of air which passes below from the poles to the equator, must be exactly balanced by an equal quantity ſlowing above in the opposite direction. , 13. Between the latitudes 30° and 40° hoth in the northern and southern hemispheres, westerly winds prevail. 14. The western coasts of the extratropical continents have a much higher mean temperature than the eastern coasts. This difference is extremely striking between the western coasts of North America, and the opposite eastern coast of Asia. It is explained by the heat evolved in the condensation of vapour swept from the surface of the ocean by the western winds. This general current in its passage over the land deposits more and more of its aqueous particles, and by the time that it arrives upon the eastern coasts is extremely dry ; as it moves onwards it bears before it the humid atmosphere of the intermediate seas, and arrives upon the opposite shores in a state of Saturation. Great part of the vapour is there at once precipitated, and the temperature of the climate raised by the evolution of its latent heat. - - 15. A wind generally sets from the sea to the land during the day, and from the land to the sea during the night, especially in hot climates. The land and sea breezes are amongst the most constant of the phenomena of the inconstant subject with which we are occupied ; the land becomes much more heated by the action of the sun's rays than the adjacent water; and || the incumbent atmosphere is proportionably rarefied ; during the day, therefore, the dense air of the ocean rushes to displace that of the land; at night, on the contrary, the deep water cools much more slowly than the land, and the reverse action takes place as these changes proceed gradually. The height of the barometer is not affected by them. . - - 16. The trade winds in the neighbourhood of the western coasts of the large continents, in their course have their direc- tion changed. . This is an effect of the same nature as that of the land and sea breezes. Those parts of Africa and America which lie between the tropics, become intensely heated by the action of a vertical sum : the columns of the atmosphere which rest upon them must therefore be highly rarefied, and the more temperate air of the surrounding seas will press upon them. This influence is so decided as to overcome the tenden- cy of the east wind; and on the western coasts of both conti- tinents a wind from the west prevails. This is again an instance of a complete perpendicular change from a permanent cause, and the total pressure is unaffected. Of the same nature are the monsoons of the Indian ocean, and other periodical winds; they are occasioned by a particular distribution of land and water, acted upon by the periodical changes of the sun’s decli- nation. While the sun is vertical to the place where they occur, the land becomes heated, and the air expanded, and the wind flows towards the coasts as the sum retires towards the opposite point of its course; the land cools faster than the sur- rounding seas, and the course of the wind is westward, the sim- plest way of regarding the sun's motion in declination, as af- fecting the temperature of the various latitudes, is to suppose a motion of the whole, system ; by which the line of greatest heat, and the two points of greatest cold, maintaining their relative distances, vibrate on either side of the earth's equator and poles. None of these changes affect the barometer. 17. Rain seldom occurs in the constant trade-winds, but abundantly and constantly in the adjoining latitudes. Between the tropics the elasticity of the aqueous vapour reaches its maximum amount, and within these limits only, rises to any extent into the upper current of the atmosphere. Its own force which is laterally exerted, is assisted by the equatorial wind, and it flows to the north and south as fast as it rises within the zone ; no accumulation can therefore be formed, and the tem- perature being remarkably steady, seldom varying more than two or three degrees, precipitation can but seldom occur. The continental parts, however, of the same regions being liable to greater vicissitudes of heat, are subject to rainy seasons, which are periodical, like the monsoons of the same climates, and are governed as they are by the progress of the sun in declination. The condensation, while it lasts, is in proportion to the density of the vapours, and is violent beyond any thing that is known in temperate climates. The alternate seasons of fine weather are distinguished by cloudless skies and perfect serenity. The extra tropical latitudes, on the contrary, beyond the bounds of the trade winds, are at all times exposed to great precipitation; the vapour in its course is subjected to a rapidly decreasing temperature, and the condensation is fed by a constant supply. We are thus led to the consideration of a temperate zone and a Variable climate. * g - 18. Between the tropics the fluctuations of the barometer do not much exceed # of an inch, while beyond this space they reach to three inches. 19. In the temperate climates the rains and the winds are variable. 20. As we advance towards the polar regions we find the irregularities of the wind increased, and storms and calms repeatedly alternate, without warning or progression. The extremes of heat and cold will sometimes prevail within a very limited compass; and forcible winds will biow in one place, when at the distance of a few leagues gentle breezes prevail. Ships within the circle of the horizon may be seen enduring every variety of wind and weather at the same moment: some under close-reefed top-sails labouring under the force of a storm ; some becalmed, and tossing about by the vio- lence of the waves, and others plying under gentle breezes, from quarters as diverse as the cardinal points. The fluctuations of the barometer are also great and sudden, proving that theory would have induced us to conclude that the irregularities of those regions extend to the higher strata of the atmosphere. 21. In the extra tropical climates, a fall in the barometer almost always precedes a fall of rain, and indicates an accele- ration or change of the aërial currents. 22. Barometers situa- ted at great distances from, each other often rise and fall toge- ther with great regularity. 23. More than two currents may often be traced in the atmosphere at one time by the motions of the clouds, &c. 24. The force of the winds does not always decrease as the elevation increases, but on the contrary is often found to augment rapidly. 25. The variations of the barometer are less in high situations than in those at the level of the sea. 26. In Great Britain, upon an average of ten years, westerly winds exceed the easterly in the proportion of 225 to 140. Of those from the east, the northerly exceed the southerly in the proportion of about 74 to 64; leaving but a very small propor- tion indeed which blow from the most irregular point, viz. the south-east. - 27. Upon the same average the northerly winds are to the southerly, 192 to 173. 28. Northerly winds almost invariably raise the barometer, while southerly as constantly depress it. 29. The most permanent rains of this climate come from the south- ern regions. 30. The mean height of the barometer varies but little with the changes of the seasons. 31. The elasticity of the aqueous vapour does not decrease gradually as we as: cend in the atmosphere, in proportion to the gradual decrease of the temperature and density of air; but the dew point remains stationary to great heights, and then suddenly falls to a large amount. 32. The tension of vapour given off in the process of evaporation is determined, not by the temperature of the evaporating surface, but by the elasticity of the aqueous at- mosphere already existing. 33. The apparent permanency and stationary aspect of a cloud is often an optical deception arising from the solution of moisture on one side of a given point, as it is precipitated on the other. 34. The quantity of vapour in the atmosphere, in the different seasons of the year, (measured on the surface of the earth, and near the level of the sea,) fol- lows the progress of the mean temperature. 35. The pressure of the aqueous atmosphere separated from that of the aërial, gene- rally exhibits changes directly opposite to the latter. 36. Great falls of the barometer are generally accompanied by a tempe- rature above the mean for the season, and great rises by one below the same. That the different phases of the moon have some connexion with changes in the atmosphere, is an opinion so universal and popular, as to be on that account alone entitled to attention. No observation is more general, and on no occa- 658 M I (; M. F. T DIGTIONARY OF MECHANICAL SCIENCE, sion perhaps is the almanac so frequently consulted, as in form- ing conjectures upon the state of the weather. The common remark, however, goes no farther than that changes from wet to dry, and from dry to wet, generally happen as the changes of the moon. When to this result of universal experience we add the philosophical reasons for the existence of tides in the aérial ocean, we cannot doubt that such a connexion exists. The subject, however, is involved in much obscurity. - METHOD, from meta, beyond, and odos, a path, literally means a path from one object to another. “The first idea of method is a progressive transition from one step in any course to another, and when the word method is used with reference to many such transitions in continuity, it necessarily implies a * principle of unity with progression.”. “If it be permitted,” says Lord Bacon, “to estimate a thing by the importance which is peculiar to it, the science, of method may be con- sidered the key of all sciences: in the same manner as the hand is the instrument of instruments, the human intelligence the designer of designs, so method ought to be the art of arts; it not only directs the mind, but strengthens its powers, as the habitual exercise of shooting arrows enables us not only to aim at an object with more precision, but also to bend the bow itself with more vigour.” All things in us and about us are a chaos if method be not present, and so long as the mind is entirely passive, so long as there is an habitual submission of the understanding to mere event and images, without any attempt to classify them, so long the chaos must continue. There may be transition, but there can never be progress; there may be sensation, but not thought, for the total want of method renders thinking impracticable. But as soon as the mind becomes accustomed to contemplate not things alone but relation of things, there is immediate need of some path or way of transit from one to the other of the things related;— there must be some law of agreement or of contrast between them ; there must be some mode of comparison, in short, there must be method. s Method, in Botany, is a mode of arrangement from certain agreements or circumstances of resemblances. There are two kinds of methods in arranging vegetables: the natural method is that which, in its distribution, retains all the natural classes; the artificial method is that, the classes of which are not natu- ral, because they collect together several genera of plants which are not connected by numerous relations, although they agree in the characteristic marks assigned to that class to which they belong. - - METHODISTS. The term Methodist was first given to Themison, the founder of a sect of physicians at Rome, which flourished about three hundred years, and had some of the greatest physicians of the age among its members. In the seventeenth century there sprung up a new species of polemic- doctors, who were denominated Methodists, and distinguish- ed themselves by their zeal and dexterity in defending the church of Rome, against the attacks of the Protestants. This sect is now no more; and the appellation is made to designate the followers of the late John and Charles Wesley, and the so- cieties founded by the Rev. George Whitefield. They are divided into Whitefieldian and Wesleyan Methodists. The members of the former division embrace the doctrines of Calvin; the latter, as far as relates to free-will, are Arminians. METROPOLIS, from meter, mother, and polis, a city. The chief city of a country. - METON, a celebrated mathematician of Athens, who flou- rished about 430 years before Christ, and to whom we owe the Metonic Cycle. METONIC CYCLE. See CYCLE. + METONYMY, is a trope in which one name is put for an- other, on account of the near relation there is between them. METRE, in Poetry, a system of feet of a just length. The different metres in poetry are the different manners of ordering and combining the quantities, or the long and short syllables; thus, hexameter, pentameter, iambic, sapphic verses, &c. con- sist of different metres or measures. In English verses the metres are extremely various and arbitrary, every poet being at liberty to introduce any new form that he pleases. The most usual are the heroic, generally consisting of five long and five short syllables, and verses of four feet, and of three feet, and a , especially by those who understand it. caesura, or single syllable. The ancients, by variously combin- ing and transposing their quantities, made a vast variety of dif- ferent measures, by forming spondees, &c. of different feet. Metre, the base of the new French system of measures. & MEZZOTINTO Scra PING, is an art of modern times, that recommends itself to us by the ease with which it is executed, In mezzotinto prints there is no etching, no strokes of the graver are seen; but the lights and shades are blended together, and appear like a drawing in Indian-ink. They are therefore different from aqua tinta; but both resemble Indian-ink, and the difference is not easily pointed out. Mezzotinto is applied to portraits and historical subjects; aqua tinta to landscapes and architecture. The tools for mezzotinto scraping are the grounding tool, burnisher, and scraper, and you proceed by the following rules:—l. To lay the mezzotinto ground, place the plate, with a piece of flannel under it, upon your table, hold the , grounding tool in your hand perpendicularly; lean upon it moderately, continually rocking your hand in a right line from end to end, till you have wholly covered the place in one direc- tion: next cross the strokes from side to side, afterwards from corner to corner, working the tool each time over the plate, in every direction, like the points of a compass; taking care not to let the tool cut (in one direction) twice in a place. This done, the plate will be full, or, in other words, all over rough alike, and would, if it were printed, appear completely black. 2. Having laid the ground, take the scrapings of black chalk, and with a piece of rag rub it over the plate; or you may smoke it with candles, as before directed for etching. 3. Now take your drawing, and having rubbed the backs with red- chalk dust, mixed with flake-white, trace it on the plate. 4. To form the lights and shadows, take a blunt needle, mark the outlines only, then with a scraper scrape off the lights in every part of the plate, clean and smooth, in proportion to the strength of the lights in your drawing, taking care not to hurt your outlines. The burnisher is used to soften or rub down the extreme light parts after the scraper has been applied; such as the tip of the nose, forehead, linen, &c. which might other- wise, when proved, appear rather misty than clear. Another method used by mezzotinto scrapers is, to etch the outlines of the original, as also the folds in drapery, making the breadth of the shadows by dots, which having bit to a proper depth with aqua fortis, take off the ground used in etching, and hav- ing laid the mezzotinto ground, proceed to scrape as above. When the plate is ready for a proof, have one pulled by the printer. When this proof is dry, touch it with white chalk where it should be lighter, and with black chalk where it should be darker; and when the print is retouched, proceed as before for the lights; and for the dark colours, use, as much as you judge necessary, a small grounding tool, to bring it to a proper colour; and when you have done as much as you think expedient, prove it again; and proceed in this manner to prove and touch, till it is entirely to your mind. MIASM, or MIAs MA, from miaimo, to infect, denotes, among physicians, those atoms or particles which arise from distem- pered or putrefying poisonous bodies, and which become the contagious effluvia of pestilential diseases, whereby they are communicated to people at a distance. MICA. This stone forms an essential part of many moun- tains, and has been long known under the names of glacies Mariae, and Muscovy glass. It consists of a great number of thin laminae adhering to each other, sometimes of a very large size. Specimens have been found in Siberia nearly 23 yards square. Its texture is foliated; its fragments flat; the la- mellae flexible, and somewhat elastic; very tough. It has long been employed as a substitute for glass, as it is not so liable to be broken by the agitation of the ship. - MICROMETER, is an instrument fitted to telescopes in the focus of the object-glass, for measuring small angles or dis- tances, as the apparent diameters of the planets, &c. Various forms have been given to this instrument by different authors, and various claims have been urged for the honour of the invention. It seems, however, to belong to Gascoigne, an Englishman, though it is doubtful whether Huygens did not also invent the one which he used, without any knowledge of that of the former. Under all the forms of this instrument, the M. I. C. M I C DICTIONARY OF MECHANICAL SCIENCE. principle of operation is the same, which is, that it moves a fine wire parallel to itself, in the plane of the picture of an object, formed in the focus of the telescope; and with such accuracy as to measure with the greatest precision its perpen- dicular distance from a fixed wire in the same plane, by which means the apparent diameters of the planets, and other small angles, are exactly determined. This may be illustrated as follows:—Let a planet be viewed through a telescope, and when the parallel wires are opened to such a distance as to appear to touch exactly the two opposite extremities of the disc of the planet, it is obvious that the perpendicular distance between the wires is then equal to the diameter of the object in the focus of the object-glass. • Let this distance, whose measure is given by the mechanism of the micrometer, be represented by the line p q ; then, since the measure of the focal distance q L may be also known, the ratio of q L to p q, that is, of radius to the tangent of the angle q Lp, will give the angle itself by a table of sines and tangents; and this angle is equal to the opposite angle P L Q, which the real diameter of the planet subtends at L, or at the maked eye. This is the general principle on which the construction of this instrument depends, and the different forms that have been given to it have been more directed towards an improvement of the mechanism than to any other object, but our limits will not allow of entering into a detail of these constructions, and we shall therefore confine our remarks to a description of the divided object-glass micrometer, as invented by Dollond, and | allowed to be the most accurate of any yet discovered. Divided Object-Glass M1CROMETER. This instrument con- sists of a convex lens divided into two equal parts C, D, by a plane which passes through its axis; and the segments are moveable on a graduated line CD, perpendicular to that axis. Let C, D, be the centre of the segments; and P, Q, two remote objects, images of which will be formed in the lines PC E, Q DE, and also in the P. foci of the segments. Let the glasses be moved till these images coincide as at E.; then † --~ C T. Gr G-Tº: _-HT § –Tº the angle PE Q, which the objects subtend at E the principal focus of C, or D, is equal to the angle which CD, the distance of the centres, subtends at the same point; and therefore, by calculating this angle, we may determine the angular distance of the bodies P and Q, as seen from E. Draw E G perpendi- cular to C D ; and, because the triangle C E D is isosceles, C G = G D, and the Z C E G = the Z. G ED; also, G D is the sine of the angle G E D, to the radius E D ; therefore, knowing E D and G D, the angle G E D may be found by the tables; and consequently 2 G E D, or C E D, may be deter- mined. The angle C E D is in general so small, that it may, without sensible error, be considered as proportional to the subtense CD. And being determined in one case by observa- tion, it may be found in any other by a single proportion. If the objects be at a given finite distance, the angle P E Q will still be proportional to CD; for on this supposition, the distance C E, or DE, of either image from the corresponding glass, will be invariable; therefore the angle C E D will be proportional to CD. The divided object-glass is applied both to reflecting and refracting telescopes; and thus small angular distances in the heavens are measured with great accuracy. - MICROPHONICS, the science of magnifying small sounds. MICROSCOPE, an instrument for magnifying small objects by means of a proper adjustment and combination of lenses or mirrors. The invention of microscopes, like most other inge- nious discoveries, has been claimed for different authors. Huygens informs us, that the first microscopes were con- structed by Drebell, a Dutchman, in 1621; but F. Fontana, a Neapolitan. in 1646, claims the invention as his own, which he dates from the year 1618. Microscopes are divided into single, compound, reflecting, solar, &c. Single or Simple Microscope, is one which consists of a single lens. Theory of Single Microscopes.—If the angle which subtends at the centre of the eye, when at a proper distance for distinct vision, be less than a certain limit, that is, if it be less than 4, it will only appear to the eye like a physical point; and if we endeavour to increase the image by bringing it nearer to the eye, the extreme rays will diverge so much as to render the object indistinct; and if the extreme rays be sloped, there will then be too little light to make the object distinctly visible; the microscope is, therefore, introduced in order to supply these defects of natural vision, which is effected by placing the object in the principal focus of a glass spherule or lens, whose focal length is short; in which case it may be distinctly seen, the visual angle, as well as the quantity of light admitted into the eye, being increased, and the parts which before appeared only as a physical point, may now be subjected to examination; the visual angle thus formed, being to that formed at the naked eye, at the least distance of distinct vision, as that distance is to the focal length of the glass. Let Q. P be an object placed in the principal focus of the lens, or spherule A E, whose centre is E.; L Q the least dis- tance at which it can be seen distinctly with the naked eye; join LP, P E. Then the angle under which the object is seen through the glass, is equal to P C Q ; and the angle under which it is seen with the naked eye, is Q LP. Also, when these angles are small, since they have a common subtense QP, they are nearly in the inverse ratio of the radii E Q, L Q ; that is, the visual angle, when the object is seen through the glass: the visual angle when it is seen with the naked eye at the distance L Q : ; L Q : * Evample. If the focal length of the glass be ºn of an inch, and at the least distance of distinct vision 8 inches, the visual angle of the object when viewed through the glass : is the visual angle when it is seen with the naked eye :: 8 : * : : 400 : i. The Double or Compound Microscope, consists of two lenses at least, but generally of three, and often more. We shall first describe the one which contains two :—The lens DE, in fig. 1, (plate OPTICs,) is therefore to be overlooked in com- paring this description with the figure. The first or smallest lens C is placed near the small object A B, at a little more than its focal distance from it; a large image of the ob- ject is thus formed, which will be as much larger than the object, as the distance C L is greater than the distance A C; and as this distance may be made greater or less by placing the object nearer to or farther from the lens C, the image may be increased or diminished at pleasure. And as this image may be distinctly viewed, and still further magnified by a convex lens MN, placed at its focal distance from the image, it is evident that small objects may be thus magnified to many times their real size.” Suppose, for example, that the distance of the object C L is 12 times the distance of the image at CA, then will the length of the image K.L be 12 times the length of the object A B, when viewed with the naked eye; but this length of the image, if viewed with an eye-glass of one inch focal distance, will appear six times as large as it does * This lens or glass being nearest the eye, is usually called the eye-glass. 660 M I C M. 1 L DICTIONARY OF MECHANICAL SCIENCE. to the naked eye, and therefore its length will appear 12 times 6, or 72 times larger than to the naked eye; and, as its breadth will be magnified in the same proportion, its surface will be 72 times 72, or 5184 times larger than that of the object when viewed with the naked eye. Though the magnifying power of this microscope be very considerable, yet the extent or field of view is very small and confined; therefore, in order to enlarge it, and to increase the quantity of light, another large lens D E, is placed between the two already noticed, (see the figure,) by which means the angle D C E or A C B, under which the visible part of the object appears, may be considerably enlarged; the image will then be formed again at FG, and as the image thus formed is now contained between the two extreme parallel rays of the eye-glass M F and N G, is wholly visible; whereas before, the part O Q could only be seen. But though the object is not quite so much magnified on the whole, in this as in the former case, yet the visible surface is very much increased by the addition of this third glass. The glass R S is a plain mirror, which is employed to reſlect the light I, in order to illuminate transparent objects when examined by this instrument. . . The Solar Microscope, invented by Dr. Lieberkhun, is em- ployed to represent very small objects on a very large scale, in a dark room. This is accomplished in the following manner: Let AB, fig. 2, plate Optics, represent a beam of the sun’s light falling on a small mirror or looking-glass D.C., adjusted by two brass wheels to such an inclination as shall reflect the rays which fall upon it parallel to the horizon, to a large con- vex lens EF, which converges them to a focus; near this focus, as at GH, is placed a small object, which is by this means strongly illuminated, and the rays which flow from it through a small convex lens I, so adjusted by a slider to a little more than its focal distance from the object, produce—a very large image KL, which being received upon a white table cloth, or allowed to fall on the opposite wall of the darkened room, will represent the object magnified in propor- tion to the distance of the picture from the lens I.” Suppose that the small lens I is one-tenth of an inch distant from the object, when the image KL is duly formed on a sheet or table cloth, at the distance of 16 feet from the small lens just mentioned; then in 16 feet there are 192 inches, and conse- quently 1920 tenths of an inch; therefore the image is 1,920 times the length of the object, and as many times its breadth: the area or surface of the image is therefore 1,920 times 1,920, or 3,086,400 times that of the object. Such is the prodigious magnifying power of the solar microscope. Harris's Improved Botanic Microscope.—This compact in- strument is found particularly to recommend itself to the practical botanist and naturalist, as a truly able assistant in their researches through the animal, vegetable, and mineral kingdoms, and more especially when its facility of management and portability, combined with its extent of magnifying power, are brought into consideration. To use this microscope, fig. 3, plate OPTICs, take its parts out of the case, unscrew the pillar A on the top, the stage B has a stem which attaches at the socket D. The three lenses at E screw into the arm C, which is fixed by the milled head F; that lens which is dotted thus ... mag- mifies the least, and the lens . the most; and by screwing into each other, seven different magnifying powers are obtained by combination: W is a yet stronger power than those at E, (which must be removed while W is in use,) being for the purpose of observing objects otherwise too minute to be seen. Transparent objects similar to those in slide Y, are examined by attaching them to the stage B, and by varying the inclinations of the mirror G, (which must be towards the light,) the objects will bave more or less light reflected on them, and by adjusting the stage B up or down by the rackwork at H, the objects are seen more or less distinctly. . When opaque objects are to be ex- amined, remove the mirror G from its box, and screw the lens ...; into the back, then fixing it by its stem to the stage B, the light of a candle is concentrated on the objects; this is * It is scarcely necessary to remark, that the lenses and object to be viewed are placed in a tube, which is screwed into a hole in the window shutter, or a board placed in the window, which serves at the same time to exclude the light. useless by day. I is a black and white piece on which opaque objects are placed, and fits the stage B. J is a screw box for confining living objects, and is also to be laid on the stage B. K a pair of steel nippers that attaches to the stage B by its stem, for holding small insects, leaves, or wings, &c. L is a pair of forceps for taking up objects too small for the touch. M and N a dissecting knife and point for separating the smaller parts of flowers, &c. The dotted outlines N représent a body that may screwed on at E, making it an improved Com- pound Microscope, affording a much larger field of view, and requires a larger case. . . . . . MICROSCOPIC OBJEcts, those things which are too small to be seen distinctly by the naked eye. . . MIDDLE LATITUD e, is half the sum of two given latitudes when they are both in the same hemisphere, or half their difference if they are in different hemispheres; in which latter case it will always be of the same name as the greater. MIDWIFERY, in the restricted sense of the word, is the art of assisting women in childbirth. It is generally, however, made to comprehend the management of women, both previous- ly to, and sometime after, delivery ; as well as the treatment of the infant in its early state. - MIGRATION of BIRDs. It has been generally believed, that many different kinds of birds annually pass from one country to another, and spend the summer or the winter where it is most agreeable to them ; and that even the birds of our own island will seek the most distant southern regions of Africa, when directed by a peculiar instinct to leave their own coun- try. It has long been an opinion pretty generally received, that swallows reside during the winter season in the warm southern regions; and Mr. Adamson particularly relates his hav- ing seen them at Senegal, when they were obliged to leave this country. But besides the swallows, Mr. Pennant enumerates many other birds which migrate from Britain at different times of the year, and are then to be found in other countries; after which they again leave these countries, and return to Britain. The reason of those migrations he supposes to be a defect of food at certain seasons of the year, or the want of a secure asylum from the persecution of man during the time of court- ship, incubation, and nutrition. - Water Fowl.—Of the vast variety of water fowl that frequent Great Britain, it is amazing to reflect how few are known to breed here: the cause that principally urges them to leave this country seems to be not merely the want of food, but the desire of a secure retreat. Our country is too populous for birds so shy and so timid as the bulk of these are: when great part of our island was a mere waste, a tract of woods and fens, doubtless many species of birds (which at this time migrate) remained in security throughout the year. Egrets, a species of heron, now scarcely known in this island, were in former times in prodigious plenty; and the crane, that has totally for- saken this country, bred familiarly in our marshes ; their place of incubation, as well as of all other cloven-footed water fowl, (the heron excepted,) being on the ground, and exposed to every one. As rural economy increased in this country, these animals were more and more disturbed ; at length, by a series of alarms, they were necessitated to seek, during the Summer, some lonely safe habitation. On the contrary, those that build or lay in the almost inaccessible rocks that impend over the British seas, breed there still in vast numbers, having little to fear from the approach of mankind; the only disturb- ance they meet, in general, being from the desperate attempts of some few to get their eggs. MILDEW, is said to be a kind of thick, clammy, sweet juice, exhaled from or falling down upon the leaves and blos- soms of plants. By its thickness and clamminess it prevents verspiration, and hinders the growth of the plant. It some- times rests on the leaves of trees in form of a fatty juice, and sometimes on the ears of corn. It is naturally very tough and viscous, and becomes still more so by the Sun's heat exhaling its more ſluid parts; by which means the young ears of corn are so daubed over, that they can never arrive at their full growth. Bearded wheat is less subject to the mildew than the common sort ; and it is observed, that newly dunged lands are more liable to mildew than others. The best remedy is a smart shower of rain, and immediately afterwards a brisk wind. M. I. L. M. I. L. DrCTIONARY OF MECHANICAL SCIFNCE 661 If the mildew is seen before the sun has much power, it has been recommended to send two men into the field with a long cord, each holding one end; and drawing this along the field through the ears, the dew will be dislodged from them before the heat of the sun is able to dry it to that viscous state in which it does the mischief. Some also say, that lands which have for many years been subject to mildews, have been cured of it by sowing soot along with the corn, or immediately after it. g MILE, (MILLE PAssus,) a measure of length or distance, containing eight furlongs, &c. See MEASURE. The English sta- tute mile is fourscore chains, or 1760 yards; that is, 5280 feet. See CHAIN, YARD, AND FOOT. tº the miles in use among the principal nations of Europe, in geo- metrical paces, 60,000 of which make a degree of the equator. Geometrical paces, yards. Mile of Russia, . . . . . . . . . e e s tº gº º ... .. 750 or 1100 of Italy, . . . . . . . . . . . . . . . . . . . . . 1000 or 1467 of England, . . . . . . . . . . . . . . . . . . 1250 or 1760 of Scotland and, Ireland, . . . . . . . 1500 or 2200 The small league, ... . . . . . . . . . . . . . . . 2000 Or 2933 The mean league, . . . . . . . . . . . . . . . . . . 2500 or 3666 The great league of France, ........ 3000 or 4400 Mile of Poland, ... . . . . . . . . . . . . . . . . . 3000 or 4400 of Spain, . . . . . . . . . . . . . . . . . . ... 3248 or 5028 of Germany, . . . . . . . . . . tº gº is e º 'º e 4000 or 5866 of Sweden, . . . . . tº s º e º ºs e º 'º e º is e º 5000 61: 7233 of Denmark, ... . . . . . . . . . . . . . . . 5000 or 7233 of Hungary, . . . . . . . . . . . . . . . . . . 6000 Or S800 MILIARY FEveR, a malignant fever so called from the erup- tion of certain pustules resembling millet-seeds. - MILITARY TActics teach the art of disposing forces in battle array, and performing its proper motions and c volu- tions. The Greeks, skilful in this part of the military art, had public professors of it, called Tactici, who taught and instructed their youth. Tactics signifies also the art of inventing and making machines for throwing darts, arrows, stones, fire-balls, &c. by means of slings, bows, and counterpoises. Naval tac- tics instruct us in the arrangement of a fleet for an engage- ment by Sea. - MILITARY Discipline, or the training of the soldiers, and the due enforcement of the laws and regulations instituted by au- thority, may be considered the soul of all armies; unless it be established with prudence, and supported with resolution, assem- błies of armed men are little better than a rabble, and more dangerous to a state than its enemies. By the force of disci- pline, men are kept in obedience to command, in opposition to the impulse of their passions, and make each army, as it were, a complicated, but immense and emergetic machine. Rank, is the appointment of officers, or a gradation of autho- tº a - rity necessary towards the establishment of discipline and sub- ordination. An army is commanded by a captain-general or commander-in-chief, and general and staff officers. the persons of their Royal Highnesses the Duke of York and the Prince of Cobourg; the Duke of Wellington, &c. shal in the French service. general, has sometimes the appointment of commander-in-chief. When an army is considerable, the following is deemed an adequate staff, exclusive of the commander-in chief: a general for the horse and one for the foot, or a general for each wing of the army ; a major-general for every two brigades; and nearly half that number of lieutenant generals. But the duties of all these are much the same ; the terms denoting chiefly the gra- dations of rank. General officers may command any number of men, from a company or troop to several regiments. Gene- rals have no pay, except when employed ; but then they have from two to ten pounds a day. - The commander-in-chief, or captain-general, or general, com- mands all the military of a nation or army ; he receives him- self his orders from the king, and communicates them to all general officers, who distribute them through all the corps of the army. Colonels command regiments—but there are lieu- tenant colonels, who are the second officers in regiments, and command in the absence of the colonels. The major-general post. We shall here give a table of | Field-mar- shals, long disused in the British army, have been revived in The rank of commander-in-chief corresponds to the degree of field mar- A lieutenant, or even a major- acts immediately under the general, receiving his orders, and delivering them out to the majors of brigades, with whom he concerts what troops are for duty or guard, detachments, con- voys, or foraging parties. The major of a regiment conveys all orders to the regiment, after he has drawn them up, sees it march, provides quarters, &c. He is the only officer of an infan- try regiment who is allowed a horse in service, to facilitate com- munications. the colonel’s absence. A brigadier commands a brigade; and In a regiment of horse, the major commands in the eldest colonels are usually such as are advanced to this Whoever is upon duty is brigadier of the day. He marches at the head of his own brigade, and is allowed a ser- jeant and ten men of his own brigade, for his guard. The rank of a brigadier general in the British service used to be suppress- ed in time.of peace. Brigadiers. or sub-brigadiers, are posts in the horse-guards. The brigadier, or brigadier-general, ap- points an officer called a brigade major, to assist him in all the management of his brigade. Experienced captains are appoint- ed to this post; and act in the brigade as major-generals do in the army, receiving their orders from their commanders. Captains. A captain-general is he who commands in chief. A captain of a troop, or company, commands a troop of horse, or coin pany of foot, under a colonel. His duty is, to be careful to keep his company full of able-bodied soldiers; to visit their tents or lodgings; to see what is wanting ; to pay them well ; and keep them neat and clean. He has the power, in his own company, of making Sergeants and corporals. In the horse and foot guards, the captains have the rank of colonels. The com- missioned officers, subordinate to the captain, are the lieute- nants and ensigns, commonly called subaltern officers. These, though their rank is not the same, perform duty together with- out distinction. Their ordinary duties are, in garrison, guards, detachments, courts martial, the visiting of hospitals and bar- racks, fatigues on working parties, and orderly duties. And no officer can exchange his duty with another, except by permission of the commanding officer. Thus, the ensign bears the colours, and has charge of them in baitle, yet is he under the lieutenant. The adjutant assists the major, and receives his orders nightly from the brigade major ; these, after being submitted to the colonel, he delivers to the sergeants. Almost all duties are re- gulated by the adjutant as major's assistant, as detachments, guards, the charge of ammunition, the prices of bread, beer, &c. The quarter-master is rather a civil than a military officer; and though next to the adjutant, he has nothing to do with the dis- cipline of the regiment. He superintends the clothing, quarters, ammunition, firing, &c. The surgeon, a commissioned officer on the staff of the regiment, requires to be skilled in physic, phar- | macy, and anatomy. The chaplain, the last commissioned offi- | cer on the staff, is generally allowed to act by deputy when he thinks proper. Serjeant-major, the first, and properly speaking the only non-commissioned officer on the staff, bears the same subordinate relation to the adjutant, as the adjutant does to the commanding officer; and as the adjutant keeps a register of the officers, so does the sergeant-major of the sergeants and corporals, whom he warns in turn for duty, and orders the quota of men each company is to furnish. The sergeant-major attends all parades, to see if the exact number of men are there, and that they are clean and well dressed. He is to make the other sergeants and corporals responsible for neglect in any of those particulars. Sergeants and corporals are also non-com- missioned officers, and superintend the private men; the drum major, the drum boys, and the private men, are mighty in their collective force in an army. MILIUM, MILLET, a genus of the digynia order, in the tri- andria class of plants ; and in the natural method ranking under the fourth order, gramina. There are twelve species, of which the most remarkable is the effusum, or common millet. MILK, a well-known fluid, prepared by nature in the breasts of women, and the udders of other animals, for the nourish- ment of their young. Its contents are of three kinds: 1st. Af oily part, which, whatever may be said concerning the origin of other oils in the body, is certainly immediately derived from the oil of the vegetables taken in, as with these it agrees very exactly in its nature, and would entirely, if we could separate it fully from the coagulable part. Another mark of agreement is their separability, which proves that the mixture has S R 662 M. I. L. M. I. L DICTIONARY OF MECHANICAL science. been lately attempted, but not fully performed. 2dly, Besides this oily, there is a proper coagulable part: And, 3dly. Much water accompanies both, in which there is dissolved a saline saccharine substance. These three can be got separate in cheese, butter, and whey ; but never perfectly so, a part of each being always blended with every other part. Milk by evaporation yields a sweet saline matter, of which Dr. Lewis gives the following proportion: - – . -- From which water ex- Twelve ounces of Left of dry matter tracted a sweet saline . - lºbstance amounting O— Cows'-milk . . . . . e tº 13 drachms. 13, drachms. Goats’ milk ... . . . . 12} . . . . . . . . - 1% - - Human milk tº e º e º a 8 -e e º e º e s e 6 . - - tº º Asses’ milk . . . . . . 8 . . . . . . . . 6 . . . . *. The saline substance extracted from asses’ milk was white, and sweet as sugar; those of the others brown or yellow, and | considerably less sweet; that from cows' milk had the least- sweetness of any. On distilling 12 quarts of milk in balneo mariae, at least 9 quarts of pure phlegm were obtained; the liquor which afterwards arose was acidulous, and by degrees tinued. After this came over a little spirit, and at last an empyreumatic oil. The remaining solid matter adhered to the bottom of the retort, in the form of elegant shining black flowers, which being calcined and elixated, yielded a portion of fixed alkaline salt. Milk set in a warm place throws up to the sur- face an unctuous cream, from which, by agitation, the butter is easily separated. The addition of alkaline salts prevents this separation, not (as some have supposed) by absorbing an acid from the milk, but by virtue of their property of intimately uniting oily bodies with watery liquors. Sugar, another grand intermedium betwixt oils and water, has this effect in a greater degree, though that concrete is by no means alkaline, or an absorbent of acids. The sweet saccharine part of the milk remains dissolved in the whey after the separation of the curd or cheesy matter, and may be collected from it in a white crystalline form, by boiling the whey till all remains of the curdled substance have fallen to the bottom; then filtering, evaporating it to a due consistence, setting it to shoot, and purifying the crystals , by solution in watér and a second crystallization. Much has been said of the medicinal virtues of this sugar of milk, but it does not seem to have any consi- derable ones: it is from cows” milk that it has been generally prepared; and the crystals obtained from this kind of milk have but little sweetness, New cows' milk, suffered to stand for some days on the leaves of butterwort or sundew, becomes uniformly thick, slippery, and coherent, and of an agreeable sweet taste, without any separation of its parts. Fresh milk added to this, is thickened in the same manner, and this suc- cessively. In some parts of Sweden, as we are informed in the Swedish Memoirs, milk is thus prepared for food. . - Milk, in the Wine Trade. The coopers know very well the use of skimmed milk, which makes an innocent and efficacious forcing for the fining down of all white wines, arracks, and small spirits ; but it is by no means to be used for red wines, because it discharges their colour. Thus, if a few quarts of well skimmed milk be put into a hogshead of red wine, it will soon precipitate the greater part of the colour, and leave the whole nearly-white: and this is of known use in the turning of red wines, when pricked, into white; in which a small degree of acidity is not so much perceived. Milk is, from this quality of discharging colour from wines, of use also to the wine- coopers, for the whitening of wines that have acquired a brown colour from the cask, or from having been hastily boiled before fermenting; for the addition of a little skimmed milk, in these cases, precipitates the brown colour, and leaves the wines almost limpid, or of what they call a water whiteness, which is much coveted abroad in wines as well as in brandies. MILK of Lime.—MILK of Sulphur. The name of milk is given to substances very different from milk properly so of the mill. lengthen or shorten the stroke of the beam-knife. , the hides, &c. called, and which resemble milk only in colour. (such is water, in which quicklime has been slaked, which acquires a whiteness. from the small particles of the lime being suspended in it, and has hence been called the milk of lime. Such also is the solu- tion of liver of sulphur, when an acid is mixed with it, by which white particles of sulphur are made to float in the liquor. Milk of Vegetables. For the same reason that milk of ani-. mals may be considered as a true animal emulsion, the emul- sive liquors of vegetables may be called vegetable milks. Ac- cordingly, emulsions made with almonds, are commonly called milk of almonds. But besides this vegetable milk, which is in some measure artificial, many plants and trees contain natu- rally a large quantity of emulsive or milky juices. Such are lettuce, spurge, fig-tree, and the tree which furnishes the elastic American resin. The milky juices obtained from all these vegetables, derive their whiteness from an oily matter mixed and undissolved in a watery or mucilaginous liquor. MILK-THISTLe. Carduus Marianus.—The young leaves in | the spring, cut close to the root with part of the stalks on, are said to be good when boiled. * - MILKY WAY. See GALAxY. . MILL, is properly an engine for grinding corn and other substances; but the same term is also used to denote a variety. of machines, particularly if the first mover be either wind or water. . . . . . . . . - * * - - º º Bark MILL, a mill constructed for the purpose of grinding grew sensibly more and more acid as the distillation was con- | and preparing bark, till it is fit for the use of a tanner. Bark- mills, like most other mills, are worked sometimes by means of horses, at others by water, and at others by wind. One of the best mills we have seen described for these purposes, is that invented by Mr. Bagnall, of Worsley, in Lancashire: this machine will serve not only to chop bark, to grind, to riddle, and pound it; but to beam or work green hides and skins out of the mastering or drench, and make them ready for the ouse or bark liquor; to beam sheepskins and other skins for the skinner's use; and to scour and take off the blºom from tanned leather, when in the currying state. The nature and connexion of its different parts may be understood from the three follow- ing figures, Plate II., MechANics. Fig. 4, is a horizontal plan Fig. 5, longitudinal section of it. Fig. 6, trans- verse section of it. A, the water-wheel, by which the whole machinery is worked, B, the shafts. C, the pit-wheel, which is fixed on the water-wheel shaft B, and turns the upright shaft . E, by the wheel F, and works the cutters and hammer by tapets. D, the spur and bevil-wheel at the top of upright shafts. E, the upright shaft F, the crown-wheel, which works in the pit-wheel C. G, the spur-nut to turn the stones I. P, the beam, with knives or cutters fixed at the end, to chop or cut the bark; which bark is to be put upon the cutters or grating i, on which the beam is to fall. Q, the tryal that receives the bark from the cutters i, and conveys it into the hopper H, by which it descends through the shoe J to the stones I, where it is ground. K, the spout, which receives the bark from the stones, and conveys it into the tryal L ; which tryal is wired to sift or dress the bark, as it descends from the stones I. M, the trough to receive the bark that passes through the tryal L. R, the hammer, to crush or bruise the bark that falls into the dish S, which said dish is on' the incline, so that the hammer keeps forcing it out of the lower side of the said dish, when bruised. k, a trough to receive the dust"and moss that passes through the tryal Q.. T, the bevil-wheel, that works in the wheel D, which works the beam-knife by a crank V at the end of the shaft w. W, the penetrating rod, which leads from the crank V to the start a. a, the start, which has several holes in it to sy, the shaft, to which the slide rods h, h, are fixed by the starts m, n, h, the slide rod, on which the knife f is fixed ; which knife is to work On the knife are two springs a, a, to let it have a little play as it makes its stroke backwards and forwards, so that it may not scratch or damage the hides, &c. 2, is a catch in the slide-rod h, which catches on the arch-head e, and the said arch-head conveys the knife back without touching the hide, and then falls back to receive the catch again. , l, the roller to take up the slide-rod h, while the hides are shifting on the beam b by pulling at the handle m. b, the beam to work the hides, &c. on. Each beam has four wheels p, p, working in a trough - - - || |- | | - | | T - - | * | | - - | - - | |- | || - || || | - - | | | N º * | | º - | - -- - | | | | - | º | - N N Nºsº ls * * sº - º |v ≤ |S || . | º | | |- M I L M I L * pict IONARY OF MECHANICAL SCIENCE. 663 road, g, g, and removed by the levers c, c. When the knife has worked the hide, &c. sufficiently in one part, the beam is then shifted by the lever c as far as is wanted. d, a press, at the upper end of the beam, to hold the hide fast on the beam while working, e, an arch-head, on which the slide-rod h catches. f. the knife fixed on the slide-rod h, to work the hides, &c. i, Cutters or grating to receive the bark for chopping. The beam P, with knives or cutters, may either be worked by tapers, as described, or by the bevil-wheel T, with a crank, as V, to cut the same as shears. The knife f is ſixed at the bottom of the start, which is fixed on the slide-rod h; the bottom of the start is split open to admit the knife, the width of one foot; the knife should have a gudgeon at each end, to fix in the open part of the start; and the two springs a, a, prevent the knife from giv- ing too much way when working; the knife should be one foot long and four or five inches broad. The arch-head e will shift nearer to, or further from, the beam h, and will be fixed so as to carry the knife back as far as is wanted, or it may be taken away till wanted. The roller l is taken up by pulling at the handle m, which takes up the slide-rod so high as to give head- room under the beam-knife. The handle may be hung upon a hook for that purpose. The slide-rod will keep running upon the roller all the time the hide is shifting; and when the hide is fixed the knife is put on the beam again by letting it down by the handle m. There may be two or more knives at work on one beam at the same time, by having different slide-rods. There should be two beams, so that the workmen could be shifting one hide, &c. while the other was working. The beam must be flat, and a little on the slope. As to the breadth, it does not signify ; the broader it is the less shifting of the hides will be wanted, as the lever c will shift them as far as the width of the hide, if required. Mr. Bagnall has formed a kind of press d, to let down, by a lever, to hold the hide fast on each side of the knife if required, so that it will suffer the knife to make its back stroke without pulling the hide up as it comes back. The slide-rod may be weighted, to cause the knife to lay stress on the hide, &c. according to the kind and condition of the goods to be worked. Hides and skins for the skinner's use are worked in the same way as for the tanners. Scouring of tanned leather for the currier’s use will be done on the beam, the same as working green hides. It is only taking the knife away, and fixing a stone in the same manner as the knife by the said joint, and to have a brush fixed to go cither before or after the stone. The leather will be better secured this way than by band, and much sooner. The whole machinery may be worked by water, wind, steam, or any other power. And that part of the machinery which relates to the beaming part of the hides may be fixed to any horse bark-mill, or may be worked by a horse or other power separately. Barker's MILI., is a kind of water-mill, invented by Dr. Barker, which without wheel or trundle performs the operation of grinding corn. This mill is represented in fig. 7, Plate II. of MechANics, in which A is a pipe or channel that brings water from a reservoir to the upright tube. The water runs down the tube, and thence into the horizontal trunk C, which has equal arms; and runs out through holes at d and e, open- ing on contrary sides near the ends of those arms. These orifices d, e, have sliders fitted to them, so that their magnitude may be increased or diminished at pleasure. The upright spindle D is fixed in the bottom of the trunk, and screwed to it below by the nut g; and is fixed into the trunk by two cross bars f: so that, if the tube B and trunk C be turned round, the spindle D will be turned also. The top of the spindle goes square into the rynd of the upper mill-stone H, as in common mills; and as the trunk, tube, and spindle, turn round, the mill-stone is turned round thereby. The lower or quiescent mill-stone is represented by I; and K is the floor on which it rests, in which is the hole L to let the meal run through, and fall down into a trough which may be about M. The hoop or case that goes round the mill-stone rests on the floor K, and supports: the hopper, in the common way. The lower end of the spindle turns in a hole in the bridge-tree G F, which sup- ports the mill-stone, tube, spindle, and trunk. This tree is moveable on a pin at h, and its other end is supported by an iron rod N fixed into it, the top of the rod going through the first bracket O, and having a screw-nut 0. upon it, above the be equal against all parts of its sides, within. bracket. By turning this nut forward or backward, the mill- stone is raised or lowered at pleasure. Whilst the tube B is kept full of water from the pipe A, and the water continues to run out from the ends of the trunk; the upper mill-stone H, together with the trunk, tube, and spindle, turn round. But if the holes in the trunk were stopped, no motion would ensue, even though the trunk and tube were full of water. For, if there were no hole in the trunk, the pressure of the water would But when the water has free egress through the holes, its pressure there is entirely removed : and the pressure against the parts of the sides which are opposite to the holes turns the machine. Mr. James Rumsey, an American gentleman, has rather im- proved this machine, by conveying the water from the reservoir, not by a pipe as A D B, in great part of which the spindle turns, but by a pipe which descends from A, without the frame L N, till it reaches as low, or lower, than G ; and then to be conveyed by a curvilinear neck and collar from G to g, where it enters the arms, as is shewn by the dotted lines at the lower part of the figure. A like improvement was made by M. Seg- ner, a German. - . . . . . - * - * Most of the authors who have attempted to lay down the theory of this mill have fallen into error: the most ingenious theory we have yet seen is by Dr. Gregory, who from a rigid investigation of the modus operandi, deduces the following easy practical rules for the construction of this mill:—1. Make each arm of the horizontal tube, from the centre of motion to the centre of the aperture, of any convenient length, not less than # of the perpendicular height of the water's surface above these centres. 2. Multiply the length of the arm in feet, by '61365, and take the square root of the product for the proper time of a revolution in seconds; and adapt the other parts of the ma- chinery to this velocity : or, 3. If the time of a revolution be given, multiply the square of this time by 1.6296 for the pro- portional length of the arm in feet. 4. Multiply together the breadth, depth, and velocity, per second, of the race, and divide the last product by 1427 times the squaré root of the height, for the area of either aperture: or, multiply the continual pro- duct of the breadth, depth, and velocity, of the race, by the square root of the height, and by the decimal '07; the last pro- duct, divided by the height, will give the area of the aperture. 5. Multiply the area of either aperture by the height of the head of water, and the product by 55.775 (or 56 lbs.) for the moving force, estimated at the centres of the apertures in pounds avoirdupois. 6. The power and velocity at the aper- tures may be easily reduced to any part of the machinery, by obvious rules. - • ' Wind MILL, as its name imports, is a machine or mill that receives motion from the impulse of the wind. Fig. 1, in the plate represents a windmill, whose internal structure is much the same as a water mill, but the external surface consists of the circular building MN, that contains the machinery; E the extremity of the wind shaft, or chief axis, which is generally inclined from 8 to 15 degrees to the horizon; and E A, E B, E C, E D, are four rectangular frames, upon which sails of cloth of the same form are stretched. At the extremity G of the sails, their surface is inclined to the axis 72°, and at their fur- thest extremities A D, &c. the inclination of the sail is about 839. Now when the sails are adjusted to the wind, which hap- pens when the wind blows in the direction of the wind-shaft E, the impulse of the wind upon the oblique sails may be re- solved into two forces, one of which acts at right angles to the windshaft, and is therefore employed solely in giving a motion of rotation to the sails and the axis upon which they are fixed. When the mill is used for grinding corn, a crown wheel, fixed to the principal axis E, gives motion to a lantern or trundle, whose axis carries the moveable mill-stone. - - IHethod of Turning the Sails to the Wind.—That the wind may act with the greatest efficacy upon the sails, the windshaft must have the same direction as the wind. But as this direction is perpetually changing, some apparatus is necessary for bringing the windshaft. and sails into their proper position. This is sometimes effected by supporting the machinery on a strong vertical axis, whose pivot moves in a brass socket firmly fixed into the ground, so that the whole machine, by means of a lever may be made to revolve upon this axis, and be properly adjust- 664 M i I, M I L DICTIONARY of MECHANICAL science. ed to the direction of the wind. Most wind-mills, however, are furnished with a moveable roof, which revolves upon friction. rollers inserted in the fixed kerb of the mill; and the adjust- ment is effected by the assistance of a simple lever. As both | these methods of adjustment require the assistance of men, it would be very desirable that the samee effect should be produ- || ced solely by the action of the wind. This may be done by | . . fixing a large wooden vane or weather-cock at the extremity | of a long horizontal arm which lies in the same vertical plane || with the, windshaft. By this means, when the surface of the vane, and its distance from the centre of motion, are sufficiently | great, a very gentle breeze will exert a sufficient force upon the vane to turn the machinery, and will always bring the sails | and windshaft to their proper position. This weather-cock, it is evident, may be applied either to machines which have a | moveable roof, or which revolve upon a vertical arbor. On the Form and Position of Wind Mill Sails.-It appears from the investigations of Parent, that a maximum effect will | be produced when the sails are inclined 543 degrees to the axis of rotation, or when the angle of weather is 353 degrees.* The angle of inclination assigned by Parent is certainly the most efficacious for giving motion to the sails from a state of rest, and for preventing them from stopping when in motion ; but he has not considered that the action of the wind upon a sail at rest is different from its action upon a sail in motion ; for since the extremities of the sails move with greater rapidity than the parts nearer the centre, the angle of weather should be greater towards the centre than at the extremity, and should vary with the velocity of each part of the sail. The following table exhibits the angle of inclination and weather which Inus; } be given to different parts of the sails. Parts of the Ra-Velocity of the . - dius from the Sail at these Angle made with Angle of centre of mo-' distances, or the axis. Weather. tion at E. values of c. - - Deg. Miin. Deg. Min. § a 63 26 || 26 34 3 § 2 a 69 54 20 6 3 # or # (L 74 I9 15 4 4 a - - # or 3 - 77 20 12 40 § 5 a 79 27 | 10 33 3 I 2 a. 81 O 9 0 Results of Smeaton's Experiments.-Mr. Smeaton found from a variety of experiments, that the common practice of inclining plane sails from 72° to 75° to the axis, was much more effica- cious than the angle assigned by Parent, the effect being as 45 to 31. the angle of inclination increased towards their extremities, they produced a greater effect than when they were weathered either in the common way, or according to Euler's theorem. But when the sails were enlarged at their extremities as repre- sented at a 3, in fig. 2, so that a 3 was one third of the radius ED, and a D to D 3 as 5 to 3, their power was greatest of all, though the surface acted upon by the wind remained the same. If the sails be farther enlarged, the effect is not increased in sproportion to the surface; and besides, when the quantity of cloth is great, the machine is much exposed to injury by sudden squalls of wind. In Mr. Smeaton's experiments, the angle of . . * The weather of the sails, is the angle which the surface forms with the plane in which they move, and is equal to the complement of the angle which that surface forms with the axis. - - - the cube of the radius. When the sails were weathered in the Dutch manner, that is, when their surfaces were concave to the wind, and when weather varied with the distance from the axis; and it ap- peared from several trials, that the most efficacious angles were * those in the following table. . . Parts of the Radius] . EA, which is di-Angle with the Axis. - Angle of Weather, vided into 6 parts. - - - 1 72 18 2 71 19 3 72 18 middle 4 74 16 5 773 12% 6 83 7 If the radius E D of the sail be 30 feet, then the sail will commence at , E D, or 5 feet from the axis, where the angle of inclination will be 72°. At # E D, or 10 feet from the axis, the angle will be 71°, and so on. - On the Effect of Wind Mill Sails.-The following maxims, de- duced by Mr. Smeaton from his experiments, contain the most accurate information upon this subject. Marim 1. The velocity of wind-mill sails, whether unloaded or loaded, so as to produce a maximum effect, is nearly as the velocity of the wind, their shape and position being the same. 2. The load at the maximum is nearly, but somewhat less than as the square of the velocity of the wind, the shape and posi- tion of the sails being the same. 3. The effects of the same sails at a maximum, are nearly, but somewhat less than, as the cubes of the velocity of the wind. 4. The load of the same sails at the maximum is nearly as the squares, and their effects as the cubes, of their number of turns in a given time. 5. When | sails are loaded, so as to produce a maximum at a given velo- | city, and the velocity of the wind increases, the load continuing the same : 1st, The increase of effect, when the increase of the | velocity of the wind is small, will be nearly as the square of | those volocities; 2dly, When the velocity of the wind is double, | the effect will be nearly as 10: 27% : But, 3dly, When the ve- | locities compared are more than double of that where the | given load produces a maximum, the effects increase nearly in | the simple ratio of the velocity of the wind. 6. In sails where the figure and positions are similar, and the velocity of the | wind the same, the number of turns in a given time will be re- ciprocally as the radius or length of the sail. 7. The load at a maximum, that sails of a similar figure and position will over- come at a given distance from the centre of motion, will be as 8. The effects of sails of similar figure and position are as the square of the radius. 9. The velocity of the extremities of Dutch sails, as well as of the enlarged sails, in all their usual positions when unloaded, or even loaded to a maximum, are considerably quicker than the velocity of the wind. - A new mode of constructing the sails of windmills has been recently given by Mr. Sutton, and fully described by Mr. Hes- leden, of Barton, in a work exclusively devoted to the subject. Mr. Sutton gives his sails the form represented in fig. 4. and makes the angle of weather at the point M, equidistant from A and B, equal to 22° 30'. The inclination of the sail at any other point N of the sail, is an angle whose sine is the distance of that point from the centre of motion A, the radius being the breadth of the sail at that point. Fig. 3, shews the angle at the different points of the sail; and the apparent and absolute breadth of the sail at these points. Mr. Sutton's mode of regu. lating the velocity of the sails, and of bringing them to a state of rest, is particularly ingenious. We shall now, therefore, proceed to describe a wind-mill, varying in many respects from the Łommon construction. This mill was invented by James Verrier, of North Curry, in Somer- setshire, who received a premium from the Society of Arts, for this useful specimen of his ingenuity. Verrier has contrived a register or regulator, by which the vanes are suffered to yield and give way to the impetus of the wind, when it is too forcible; and when it is too languid, it brings the vanes up to the wind, // ſº - | º Zºº / 2. º 7. / Zºº º wº- º º - - --- º 'º anº. -*. - ºr ºf ººººes ºve ºf zºº. ºw, or we ºw/. - | --- | º, . | º - | | M I L M I L 665 Diction ARY of MechANIcAL science. till its force is sufficient to give the mill a proper degree of ve- locity; by this contrivance, the wind is justly proportioned to the resistance or number of stones put to work, and the mill less liable to be set on tire, or destroyed by the violence of its motion. The vertical shaft of this mill is also much shorter than usual, in consequence of which the whole building (and especially the floor on which the stones are placed) is consider- ably stronger, and less liable to vibrate than in the common mills. - . , , This mill, which has eight quadrantsails, is represented in fig.5, plate WINDMILLs, where AAA are the three principal posts, 20 feet, 7% inches long, 22 inches broad at their lower extremities, 18 inches at their upper, and 17 inches thick. The column B is 12 feet 10, inches long, 19 inches in diameter at its lower extremity, and 16 inchés at its upper; it is fixed in the centre of the mill, passes through the first floor E, having its upper end secured by the rails G. G. E E E are the girders of the first floor, one of which is only seen, being 8 feet 3 inches long, 11 inches broad, and 9thick; they are mortised into the prin- cipal posts A A A and the column B, and are about 8 feet 3 inches above the ground floor. D D D are three posts, 6 feet 4% inches long, 9 inches broad, and 6 inches thick; they are mortised into the girders E F of the first and second floor, 2 feet 4 inches distant from the posts, A. &c. F F F are the girders of the second floor, 6 feet long, 11 inches broad, and 9 thick: they are mortised into the posts A, &c. and rest upon the upper ends of the posts D, &c. The three rails G G G are 3 feet 13 inch long, 7 inches broad, and 3 thick: they are mortised into the posts D and the upper end of the column B, 4 feet 3 inches above the floor to their upper edges. P is one of the arms which support the extremities of the bray-trees; its length is 2 feet 4 inches, its breadth 8 inches, and its thick- ness 6 inches. I is one of the bray-trees into which the extre- mity of one of the bridge-trees K is mortised. Each bray-tree is 4 feet 9 inches long, 9} inches broad, and seven thick; and each bridge-tree is 4 feet 6 inches long, 9 inches broad, and 7 thick, being curved 9 inches from a right line, and furnished with a piece of brass on its upper surface, to receive the under pivot of the mill-stones. L L are two iron screw bolts which raise or depress the fore-ends of the bray-trees. M M M are the three millstones, and N N N the iron spindles, each 9 feet long, on which the upper mill-stones are fixed. O is one of three wallowers which are fixed in the upper ends of the spin- dles N N N ; they are 16 inches in diameter, and each is fur- nished with 14 trundles. fis one of the carriage-rails in which the upper pivot of the spindle turns, and is 4 feet 2 inches long, 7 inches broad, and 4thick. . It turns on an iron bolt at one end, the other end sliding in a bracket fixed to one of the joists, and forms a mortise in which a wedge is driven to set the rail and wallower in or out of its work: t is the horizontal spur-wheel that gives motion to the wallowers; it is 5 feet 6 inches diameter, is fixed to the perpendicular shaft T, and has 42 cogs or teeth. The perpendicular shaft T is 9 feet 1 inch long, and 14 inches in diameter, having two iron spindles, the under spindle turns in a brass block let flush into the higher end of the column B, and the upper spindle turns in a brass plate inserted into the lower surface of the carriage rail C. The spur-wheel r is fixed on the upper end of the vertical shaft T, and is turned by the crown wheel v on the windshaft e ; it is 3 feet 2 inches in diameter, and is furnished with 15 cogs. The carriage rail C, which is fixed on the sliding kerb z, and sup- ports the upper pivot of the vertical shaft, is 17 feet 2 inches long, 1 foot broad, and 9 inches thick. YY Q, is the fixed kerb, 17 feet 3 inches diameter, 14 inches broad, and 10 thick; being mortised into the posts A A A, and fastened with screw bolts. The sliding kerb z is of the same diameter and breadth as the fixed kerb, but its thickness is only 7% inches. It re- volves on 12 friction rollers inserted on the upper surface of the kerb Y Y Q, and has 4 iron half staples Y Y, &c. fastened on its outer edge, the perpendicular arms of which are 10 inches long, 2 inches broad, and 1 inch thick, and embrace the outer edge of the fixed kerb, to prevent the sliding one from being blown off. The capsills X, W, of the mill are 18 feet 9 inches long, 14 inches broad, and 1 foot thick; they are fixed at each end with strong iron screw bolts to the sliding kerb, and to the carriage-rail C. On the right hand of w is seen the extremity 68. - - of a cross rail, which is fixed into the capsils X and v # strong iron bolts; e is a bracket 5 feet long, 16 inches in i extreme breadth, and 10 inches thick; it is bushed with a strong brass collar, in which the under spindle of the windshaft turns, and is fixed to the cross rail w, with iron screw bolts, and nuts; b is another bracket 7 feet long, 4 feet broad, and 10 inches thick; itis let into the four ends of the capsils, and that it may embrace the collar of the windshaft, it is divided into two parts, which are fixed together with screw bolts. The wind- shaft c is 15 feet long, 2 feet in diameter at the fore end, and 18 inches at the back end; its pivot at the back end is 6 inches diameter; and the shaft has a hole bored through it to admit an iron rod to pass easily through. The vertical crown wheel. v is six feet in diameter, having 54 cogs which turn the spur wheel r. The bolster d, which is 6 feet 3 inches long, 13 inches broad, and 6 thick, is tenoned in the cross rail w, directly un- der the centre of the windshaft, having a brass pulley fixed, in a mortise at its fore end. On the upper surface of this bolsteris a groove in which the sliding bolt R moves, having a brass stud at its fore end. This sliding bolt is not distinctly seen in the figure, but the round top of the brass stud is visible below the letter h; the back end of the iron rod that passes through the windshaft bears against the brass stud. The sliding bolt is 4 feet 9 inches long, 9 inches broad, and 4 inches thick. At its fore end is fixed a line which passes over the brass pulley in the bolster, and appears at a with a weight attached to its other end, sufficient to make the sails face the wind that is strong enough to work the number of stones employed; and when the pressure of the wind is more than sufficient, the sails turn on an edge, and press back the sliding bolt, which pre- vents their going with too great velocity; and whenever the wind abates, the sails by the weight a are pressed up to their proper place again. By this apparatus the wind is regulated, and justly proportioned to the resistance or work at any time to be performed; an uniformity of motion is likewise secured, and the mill is far less likely ever to move with so rapid a motion as to risk its destruction. , That the reader may understand how these effects are pro- duced, we have represented, in fig. 6, the iron rod and the arms which bear against the vanes or sails; a his the iron rod which passes through the windshaft c in fig. 7; h is the extremity which moves in the brass stud that is fixed upon the sliding bolt; ai, ai, &c. are the cross arms at right angles to a h, whose extremities i, i, similarly marked in fig. 7, bear upon the edges of the vanes. The arms a are 65 feet long, reckoning from the centre a, 1 foot broad at the centre, and 5 inches thick; the eight arms m, n, &c. that carry the sails are 183 feet long, their greatest breadth is 1 foot, and their thickness 9 inches, gradu- ally diminishing to their outer ends, where they are only 3 inches in diameter ; the inner ends of these arms are mortised into the windshaft. The 4 cardinal sails m, m, m, m, are each 13 feet long, 8 feet broad at their outer ends, and 3 feet at their lower extremities; p, p, &c. are the four assistant sails which have the same dimensions as the cardinal ones, to which they are joined by the line S S S S. The angle of the sail’s inclina- tion, when first opposed to the wind, is 45 degrees, and regularly the same from end to end. It is evident from the preceding description of this machine, that the windshaft c moves along with the sails; the vertical crown wheel v drives the spur wheel r, fixed upon the axis T, which carries also the spur wheel t. This wheel impels the three wallowers O, one of which only is seen in the figure; these being fixed upon the spindles N, &c. communicate motion to the turning mill-stones. Mr. John Bywater, of Nottingham, took out a patent in Sep- tember, 1804, for a method of clothing and unclothing the sails of windmills while in motion, (provided they are made after the Dutch manner,) by which the mill may be clothed either in whole or in part, in an easy and expeditious manner, by a few revolutions of the sails, whether they are going fast or slow, leaving the surface smooth, even, and regular in breadth from top to bottom ; and in like manner the cloth, or any part of it, may be rolled or folded up to the whip at pleasure, by simple and durable machinery. The invention consists in either fold- ing or unfolding the cloths while the sails are in motion, by . means of cylinders or rollers of any shape, as long as the sails, 8 G. - - * §§ M I L Digtion ARY OF MECHANICAL scIENGE. M I L with a toothed wheel at one end of each, working either directly ër indirectly into two wheels without arms, which are hung so âs to turn upon a ring of iron fixed to the shaft-head close be- hind the back stocks, and which may be alternately stopped; $o that the wheels at the ends of the cylinders must directly, 6r" by means of a connexion of wheels called carriers or nuts, work into them, by revolving round them through the power of the wind acting on the sails; so that the cylinders finust necessarily turn round, and roll up or fold, or unroll or unfold the cloth which is fastend to them, according to the respective wheel, without arms, which is stopped for that pur- pose. Such is the general contrivance; a detailed account with figures may be seen in the Repertory of Arts, &c. vol. vi. "On Horizontal Wind Mills.-Various opinions have been en- tertained respecting the relative advantages of horizontal and vertical wind-mills. Mr. Smeaton, with great justice, gives a decided preference to the latter; but when he asserts that hori- zontal wind-mills have only # or thof the power of vertical ones, he certainly forms too low an estimate of their power. Mr. Beatson, on the contrary, who has received a patent for the construction of a new horizontal wind-mill, seems to be preju- diced in their favour, and greatly exaggerates their compara- five value. From an impartial investigation, it will probably appear, that the truth lies between these two opposite opinions; büt before entering on this discussion, we must first consider the nature and form of horizontal wind-mills. In fig. 4, C K is the windshaft, which moves upon pivots. Four cross bars, CA, C D. I B, FG, are fixed to this arbour, which carry the frames API B, D EFG. The sails A I, EG, aré'stretched upon these frames, and are carried round the axis C K, by the perpendicular impulse of the wind. Upon the axis C K, a toothed. wheel is fixed, which gives motion to the particular machinery that is employed. In the figure only two sails are represented ; but there are always other two placed at right angles to these. Now, let the sails be exposed to the wind, and it will be evident that no motion will ensue; for the force of the wind upon the sail AI, is counteracted by afi'êqual and opposite force upon the sail E. G. In order, then, that the wind may communicate motion to the machine, the force upon the returning sail E G must either be removed by screening it from the wind, or diminished by making it present a less surface when returning against the wind. The first of these methods is adopted in Tartary, and in some provinces of Spain; but is objected to by Mr. Beatson, from the inconve- nience and expense of the machinery and attendance requisite for turning the screens into their proper positions. Notwith- standing this objection, however, Mr. Beatson thinks that this is the best method of diminishing the action of the wind upon the returning sails, for the moveable screen may easily be made to follow the direction of the wind, and assume its proper position, by means of a large wooden weathercock, without the aid either of men or machinery. It is true, indeed, that the resistance of the air in the returning sails is not completely removed; but it is at least as much diminished as it can be by any method hitherto proposed. Besides, when this plan is resorted to, there is no occasion for any moveable flaps and hingeå, which must add greatly to the expense of every other method. - º - The mode of bringing the sails back against the wind, which Mr. Beatson invented, is perhaps the simplest and best of the kind. He makes each sail A H to consist of six or eight ſlaps or vanes, A Pb 1, b 1 c 2, &c. moving upon hinges represented by the dark lines, A P, b 1, c 2, &c. so that the lower side b 1, of the first flap overlaps the hinge or higher side of the second flap, and so on. When the wind, therefore, acts upon the sail AI, each flap will press upon the hinge of the one immediately below it, and the whole surface of the sail will be exposed to its action. But when the sail AI returns against the wind, the flaps will revolve round upon their hinges, and present only their edges to the wind, as is represented at EG, so that the resistance occasioned by the return of the sail must not be di- minished, and the motion will be continued by the great supe- riority of force exerted upon the sails in the position AI. In r sistance opposed to it by the edges of the ſlaps in EG, Mr. computing the force of the wind upon the sail AI, and the re- Beatson finds, that when the pressure upon the former is 1872 pounds, the resistance opposed by the latter is only about 36 pounds, or 3, part of the whole force; but he neglects the action of the wind upon the arms CA, &c, and the frames which carry the sails, because they expose the same surface in the posi- tion AI, as in the position EG. The omission, however, has a tendency to mislead us in the present case, as we shall now see, for we ought to compare the whole force exerted upon the arms, as well as the sail, with the whole resistance which these arms and the edges of the flaps oppose to the motion of the wind- mill. By inspecting fig. 4, it will appear, that if the force upon the edges of the ſlaps, which M. Beatson supposed to be 12 in number, amounts to 36 pounds, the force spent upon the bars CD, D G, G F, F E, &c. cannot be less than 60 pounds. Now, since these bars are acted upon with an equal force, when the sails have the position AI, 1872 + 60 = 1932 will be the force exerted upon the sail A I, and its appendages, while the oppo- site force upon the bars and edges of the flaps when returning against the wind will be 36 + 60 = 96 pounds, which is nearly; of 1932, instead of , as computed by Mr. Beatson. Hence we may see the probable advantages of a screen over moveable flaps, as it will preserve, not only the sails, but the arms and the frame which support it, from the action of the wind. . . We shall now conclude this article with a comparison of the power of horizontal and vertical wind-mills. Mr. Smeaton rather underrated the former, while he maintained that they have only ; or º the power of the latter. He observes, that when the vanes of a horizontal and vertical mill are of the same dimensions, the power of the latter is four times that of the for- mer, because, in the first case, only one sail is acted upon, at once, while in the second case all the four receive the impulse of the wind. This, however, is not strictly true, since the verti- cal sails are all oblique to the direction of the wind. This calcu- lation proceeds upon a supposition, that the whole force exert- ed upon vertical sails is employed in turning them round the axis of motion; whereas a considerable part of this force is lost in pressing the pivot of the axis or windshaft against its gudgeon. Mr. Smeaton has overlooked this circumstance, otherwise he could never have maintained that the power of four vertical sails was quadruple the power of one horizontal sail, the dimensions of each being the same. Taking this cir- cumstance into the account, we cannot be far wrong in saying, that in theory at least, if not in practice, the power of a horizon- tal wind-mill is about 3 or 3 of the power of a vertical one, when the quantity of surface and the form of the sails are the same, and when every part of the horizontal sails has the same distance from the axis of motion as the corresponding parts of the ver- tical sails. But if the horizontal sails have the position AI, E G, in fig. 4, instead of the position C A d m, CD on, their power will be greatly increased, though the quantity of surface is the same, because the part C P 3 m being transferred to. BI 3 d, has much more power to turn the sails. - Smeaton's Machine for Experiments on Wind Mill Sails.-In the experiments with this machine, the sails were carried round in the circumference of a circle, so that the same effect was produced as if the wind had struck the sails at rest with the velocity which was then given them. In the pyramidal frame, fig. 7, A B C is fixed the axis D E, which carries the arm. FG with the sails G. I. By pulling the rope Z, which coils round the barrel H, a motion of rotation is given to the sails, so that they revolve in the circumference of a circle, whose ra- dius is D.I. At L is fixed a cord which passes round the pul- leys M, N, O, and coils round a small cylinder on the axis of the sails, and raises the scale C, in which the different weights. are placed for trying the power of the sails, and which being in. the direction of the axis DE, is not affected by the circular motion of the arm D G. The scale C is kept steady by the pillars Q, R, and prevented from swinging by the chains S, T, which hang loosely round the pillars. V X is a pendulum com- posed of two leaden balls moveable upon a wooden rod, so that they can be adjusted to vibrate in any given time. The pen- dulum hangs upon a cylindrical wire, on which it vibrates as on a rolling axis. - - Canicular MILL for Grinding Indigo, &c.; so named because. a dog, is the first mover. In many parts of Scotland the country dyers use this machine, as exhibited in fig. 8, plate WIND Mills, M. I. L * which is a side elevation or profile"of the whole machine. A'is the walking or canicular wheel, about 21 faet diameter, in which the patient dog walks or runs, producing by means of the equalizing action of the fly wheel K, fixed at the extremity of the shaft, an uniform velocity of from 3 to 6 miles per hour. C is a cross-beam, in which, and a corresponding piece in the floor, works the perpendicular shaft D, on which shaft is fixed the lantern E, driven by the wheel e, e, set on the inner face of the walking wheel; H, a pinion set on the shaft D.; F, a horizontal arm fixed to the shaft D, and in one extremity of which, and the opposite point in the upper cover of the lantern E, the box G is set on pivots; L, an iron vessel, placed within the box, and containing the materials to be pulverized, toge- ther with three 18 lb. iron shots; I is a wheel under the bottorn of the box G, driven by the pinion H. The action of the machine will now be readily understood. E is driven by the action of the first mover; H, set on the same shaft will drive I, giving G and the vessel L a horizontal motion on its pivots; while E carries it horizontally about the shaft D : the compound motion, then produced will effect the operation of grinding, by the centrifugal motion of the balls. - Fig. 9 is a portion of the wheel A, seen in profile, or in front elevation, and having one of its sides taken off to exhibit the action of the dog at B; C is an aperture in any part of one side, for the ingress and egress of the animal ; D Shews the situations of the balls when the machine is in action ; E is inserted to afford the opportunity of explaining, that the figure of the vessel L. must be varied with the required rate of motion. If the velocity be reduced, either by the circum- stances of the material, or the incapacity of the animal, the vessel must assume a flatter figure, as E.; if the velocity be in- creased, the vessel must be deeper, in proportion to its width. Rustall's Family. MILL cannot but be highly useful in the country, and we shall here describe the Family Mill and Bolter of Mr. Rustall, of Purbrook-heath, near Portsmouth, for which he received a premium of 40 guineas from the Society of Arts. In plate MANGLE, &c. fig. 10, A is the handle of the mill; B one of the millstones, which is about 30 in. in diameter, and 5 in. in thickness, moving with its axis C; D is the other millstone, which, when in use, is stationary, but which may be placed near to, or at a distance from, the moveable stone B; by means of three screws passing through the wooden block E, that sup- ports one end of the axis C; after it has been put through a hole or perforation in the bed stone. The grain likewise passes through this perforation from the hopper F, into the mill. F represents the hopper, which is agitated by two iron pins on the axis C, that alternately raise the vessel containing the grain, which again sinks by its own weight. In conse- quence of this motion, the corn is conveyed through a Spout that passes from such hopper into the centre of the mill behind, and through the bedstone D. G., a paddle regulating the quantity of corn to be delivered to the mill ; and, by raising or lowering which, a larger or smaller proportion of grain may be furnished; H, the receptacle for the flour, into which it falls from the millstones, when ground ; I represents one of the two wooden supporters on which the bedstone D rests. These are screwed to the block E, and likewise mortised into the lower framework of the mill at K, which is connected by means of the pins or wedges L,L,L, that admit the whole mill to be easily taken to pieces; M, a fly wheel, placed at the furthest extremity of the axis C, and on which another handle may be occasionally fixed; N, a small rail, serving to keep the hopper in its place; the furthest part of such hopper resting on a small pin, which admits of sufficient motion for that vessel to shake forward the corn; O, a spur rail, for strengthening the framework of the mill ; P, the front upright that is, mortised into the framework, and serves as a rest for the end of the iron axis C, which is next to the handle. Lastly, there is a cloth hood fixed to a broad wooden hoop, which is placed over the stones, while working, to prevent the finer particles of flour from escaping. The bolter is here represented with its front removed, in order to display its interior structure; the machine being 3 feet 10 inches in length, 19% inches in breadth, and 18 inches in depth. A is a moveable partition, sliding about 4 feet back- wards or forwards, from the centre of the box, upon two 1ſt . DICTIONARY OF MECHANICAL SCIENCE. * Mſ. If L . wooden ribs, which are fixed to the back and front of the box, and one of which is delineated at the letter B; C, the lid of the bolter, represented open; D, a slider, which is moveable in a groove made in the lid, by means of two handles on the back *ºmºsºm-º: Q, Y. ºf § ſ º ğ #illilillſ, * of such lid; E, a forked iron fixed in the slider D, and which, when the lid is shut, takes hold of the edge of the sieve F, and moves it backwards and forwards on the wooden ribs B, according to the agitation of the slider; G represents a fixed partition in the lower centre of the box, which it divides into two parts, in order to separate the fine from the coarse flour. from this partition the slider A moves each way about four inches, and thus affords room for working the sieve ; H, a board that is parallel to the bottom of the bolter, and forms part of the slider A ; this board serves to prevent any of the sifted matter from falling into the other partition; I represents two of the back feet, which support the bolter. * , Fig. 11 of the plate above mentioned, is a view of the top, or upper part, of the lid of the bolter; K, the slider that moves the lengthwise of the bolter; L., L, the handles by which the slider is worked; M, a screw serving to hold the fork, which imparts motion to the sieve. - Q represents the forked iron E separately from the lid. Both the mill and bolter may be constructed at a moderate expense. The former may be worked even in a public kitchen, or within a room in a farm house, without occasioning any great incum- brange. The particular excellence of the mill consists in this circumstance, that, from the vertical position of its stones, it may be put in action without the intervention of cogs or wheels. It may be adapted to the grinding of malt, the bruising of oats for horses, and for making flour, or for all these purposes. Another advantage peculiar to Mr. Rustall’s con- trivance is, that one man is sufficient to work it; though a man and a boy will be able to produce, in two hours, a quan- tity of flour sufficient to serve a family of six or eight persons, for a whole week;—repeated trials have proved, that the mill grinds the corn completely, and at the rate of one bushel of wheat within the hour. * p * Improved Gunpowder MILL, for lessening the destructive effects of Explosion, by Mr. Monk, manager of the gunpowder mills of Messrs. Burton, near Tunbridge, a model and descrip- tion of which were presented to the Society of Arts in 1819, who voted the inventor its silver medal, and 20 guineas. - In plate MANGLEs, fig. 12, a a is a compound lever formed of two iron bars, the extremities of which terminate above the bed- stones of the pair of mills AB; these levers are connected at their other extremities by a bolt at b, forming a joint, and per- mitting the levers to move so as to form a very obtuse angle, when a power from below upwards is applied to either of the ends of the levers a a, as shewn by the dotted lines. cc, are two oblong holes in the lever bars, through which two screws are put, which being screwed into the two uprights, constitute. the two fixed fulcrums of the lever, dd, are two uprights, with *** . & **. lever, which are made long enough to allow the bars to take e e, are two blowers | wheel. n n, two horizontal bevil wheels working in m m, and M I L an eye or loop in each, to receive and, steady the ends of the the position indicated by the dotted lines. made of thin sheet iron, in the form of hollow three-sided pyramids, and are suspended by two iron rods to the ends of the levers a a. These blowers are placed as near as possible to the tops of the upright stone shafts, and as close to the wheels as the timber will allow. ff, are two copper chains, attached by one end to the lever bars, and by the other supporting two copper valves which are not seen in fig. 1, being inside the tubs, but one of them is shewn at g, in the section of a tub, fig. 2. h h, are two oval tubs capable of holding about six gal- lons of water, having a circular hole at the bottom. Surround- ing this hole is a grooved block having a channel all round it, into which the bottom edges of the cylindrical valves fit, shewn in section at fig. 2. ii, are two small spring catches fastened to the two uprights. The lever bars are laid on the top of these catches, so that when the ends of the lever rise, that part of the lever which is on the catch moves downward, as shewn by the dotted lines, till it slips over the end of the catch ; and thus the lever is prevented from resuming its horizontal position, till released from the catch. In order to fit that part of the apparatus above described for action, bring “he lever to a horizontal position, place the valve g in the circular channel at the bottom of the tub so as to cover the hole; fill the channel with mercury, and then fill the tub with water. Hence it is evident, that the water is prevented by the mercury from escaping out of the tub, so long as the valve remains in its place. Now, if an explosion happen in either of the mills, the blower e hanging over the bedstone, will be thrown up, and the lever will in consequence be brought into the position indicated by the dotted line, and will be retained there by the spring catches i i ; at the same time the valves g will be drawn up out of the mercury, and the water in both the tubs will pour down on their respective bedstones, extinguishing in one the inflamed powder, and in the other preventing it from taking fire. In a certain stage of the grind- ing the materials of the powder are apt to clot, and adhere to the runners; parts of the bedstones are thus left bare, and the runner and bedstone coming in contact, an accidental spark may be elicited, and an explosion ensue. To prevent this most usual cause of accidents, Mr. Monk fixes to the axle of the wheel a scraper, formed of a curved piece of wood k, shod with copper, which being placed behind, and almost touching each of the runners, scrapes off the powder as it collects, and thus keeps the bedstone always covered. l, is the great water wheel which gives motion to the rest. m m, are two vertical bevil wheels fixed on the axis of the great turning the vertical shafts, upon the upper part of which are also fixed two horizontal wheels o o, which drive the wheels pp. To the shafts of these latter wheels are fixed the runners q q.7, which traverse on the bedstones u w. v, v, are the curbs sur- rounding the bedstone, to prevent the powder from falling off. The Mill A presents a view, and the mill B a section of the bedstone and curb. Fig.2 shews the position of the apparatus after an explosion has taken place, the valve being raised up out of the channel, and the water pouring down on the bedstone. It appears by several certificates, that since these improved mills have been constructed by Mr. Monk, occasional explo- sions have taken place, which before generally took place under both pair of stones ; but since that time, by the effect of instantaneously wetting the powder under the contrary pair of stones, to those where explosion had taken place, a double disaster has been prevented; and in the short space of three years, in a single manufacturing establishment, eight mills have been saved from destruction, and probably many lives. Pasley's Proposal for increasing the Strength of Gunpowder.— In the annexed figure A. D is a longitudinal section of a great gun : C the cartridge; B the ball; E a hollow metal sphere, similar to a bomb-shell or hand-grenade, with a hollow neck or tube G, which screws into the breech of the gun; F the touch-hole. The design is, that the ignited powder in the shell shall throw a quantity of flame suddenly into the gun, and explode every DICTIONARY OF MECHANICAL SCIENCE. s. |. grain of the cartridge powder. It is not, however, meant that M. I. L. ** $ Fº any of the powder from being s blown out unignited is to give the additional sº ce ; on the contrary, it is certain that the expansive powerºeſºexplosive mixtures is as the quantity of flame suddenly formed by , them, particularly in confined situations, where the flame is supplied with matter from the combustible substance itself only. In proof of this, let, flame be communicated to the powder of a charged gun, by firing a pistol containing powder only in its touch- hole, and the result will be found to be, that the momentum of the ball from the gun will be much greater than if the same quantity of powder as that fired from the pistol had been added to the cartridge in the gun, and the whole exploded in the customary manner. This was ascertained by experiment nearly ten years since. The thing is now put beyond all manner of doubt, from the dis- charge of guns being effected by detonating copper caps. Sportsmen using the same declare, that a less quantity of powder pro- duces an equal effect to a greater quantity without these caps. It may be necessary to add, that trials are indispensable to ascer- tain the maximum of the size of the shell E, and of the quantity of powder it should con- tain to be safe and most efficient.—Query. Might not the guns of forts be constructed so as to slide backwards and for- wards on fired but centered carriages, by which much fatigue would be avoided by the men 2 See GUNPowder. Mills, Horse and Hand. These machines derive their action from animal force. In horse-mills, one, two, or more horses, or other cattle, are made either to draw, or push before them levers, which project. from a centre, shaft bearing the great horizontal wheel that gives motion to the more remote parts, and which act with more or less effect, according to the length of the levers and the number of cattle employed. MILLs, Oil, are very simple in their construction; they being nearly the same as cider-mills; consisting of troughs wherein the seed is broken by the passage of immense cylinders, or cones, of iron or stone, and afterwards put into presses for the purpose of forcing the oil from the residuum. See OIL Mill. Mills, Copper and Brass, are almost invariably worked by water, having large wheels that give immediate action to ham- mers of great weight; these beat out the large slabs and bricks of metal into various forms, such as kettles, coppers, boilers, &c. and roll out sheets for various purposes, but espe- cially for coppering the bottoms of ships. This process is ef- ted by passing the heated metal between two cast-iron cylin- ders, of about a foot diameter, which having contrary motions, draw it through a small interval left between them ; and by reducing the thickness, give greater surface to the sheet. MiLLs, Silk, Cotton, &c. require much delicacy in their con- struction; their principal movements depend on the same prin- ciples as those of the mills described: the more minute parts, such as the bobbins, &c. being moved by means of one or more leather straps passing them in close contact, so as to occasion them to revolve with an astonishing degree of velocity. See SPINNING. t . . . . . . . . - M1LLs, Saw, though extremely simple in their parts, require the greatest care in their formation. The saws, which are mov- ed by cranks, must be set with most scrupulous exactness. . In most instances the timber is brought forward to the saw by means of a small toothed wheel, and an axle whereon the rope that pulls the timber is gradually coiled. See SAW. - Mills, Flaw, are génerally worked by cattle; their construc- ction is simple; the essential parts being the hackle, which combs the flax; and the scutcher, which strikes it: both tend to clearing away the coarser and unequal fibres, and to pre- pare the material for being spun either by hand or by means of machinery. See FLAX and HEMP. • * MILLENARIANS, or Chiliasts, a name given to those who, in the primitive ages, believed that the saints will one day } |I. reign on earth with Jesus Christ a thousand years. Llanoſes and/ .1// º / º º ºf - - - D - A. - ''', * tº ". &– a - - a G = º \ - \ J/any/e a -- - - A. º - (, - º 'ſº ~}}}}}}}}}}}}}} n nun | º º | - - _r-r-r-r-r-rº r * * ſº ºf 1 / 1 / 1 / 1 / ºr ºr 1 ºr - - Dººr \ ºt -- º mºſt - - Peº's - * - º d : - - º "I /custal/s fam/, /// - ºr ſº. - - Zºº // 1ſon/…/maroved own/powder lſº M I M M I N 669 DICTIONARY OF MECHANICAL SCIENCE. MILLION, in Numeration, is one thousand thousands, or 1,000,000. See NUMERAtion. . . . . . . MILLREE, a Portuguese gold coin, value 5s. 73d. English. MILT, in Anatomy, a popular name for the spleen. MILT, or Melt, in Natural History, the soft roe in fishes; thus called from its yielding, by expression, a whitish juice resembling milk. See Roe. The milt is properly the seed or spermatic part of the male fish. The milt of a carp is reckoned a choice bit. It consists of two long whitish irregular bodies, each included in a very thin fine membrane. M. Petit con- sidered them as the testicles of the fish wherein the seed is pre- served; the lower part next the anus, he supposes to be the vesiculae seminales. MIMOSA, the Sensitive Plant, a genus of the polygamia order, in the monoecia class of plants, and in the natural me- thod ranking under the 33d order Tomentaceae. The name mi- mosa, signifies “mimic; ” and is given to this genus on account of the sensibility of the leaves, which, by their motion, mimic or imitate the motion of animals. This genus comprises 85 different species, all natives of warm climates. The sensitive kinds are exceedingly curious plants, in the very singular cir- cumstance of their leaves receding rapidly from the touch, and running up close together; and in some sorts, even the foot- stalks are affected, so as instantly to fall downwards as if held by hinges, which last are called humble sensitives. They have all winged leaves, each wing consisting of many small pinnae. “Naturalists,” says Dr. Darwin, “ have not explained the immediate cause of the collapsing of the sensitive plant; the leaves meet and close in the night during the sleep of the plant, or when exposed to much cold in the day-time, in the same manner as when they are affected by external violence, folding their upper surfaces together, and in part over each other like scales or tiles, so as to expose as little of the upper surface as may be to the air; but do not, indeed, collapse quite so far, for when touched in the night during their sleep, they fall still further; especially when touched on the foot-stalks between the stems and the leaflets, which seems to be their most sensi- tive or irritable part. Now, as their situation after being ex- posed to external violence resembles their sleep, but with a greater degree of collapse, may it not be owing to a numbness or paralysis consequent to too violent irritation, like the faintings of animals from pain or fatigue : A sensitive plant being kept in a dark room till some hours after day-break, its leaves and leaf-staks were collapsed as in its most profound sleep, and on exposing it to the light, above twenty minutes passed before the plant was thoroughly awake, and had quite expanded itself. During the night the upper surfaces of the leaves are oppress- ed; this would seem to shew that the office of this surface of the leaf was to expose the fluids of the plant to the light as well as to the air.” The common sensitive humble plant rises with an under shrubby prickly stem, branching six or eight feet high, armed with crooked spines; conjugated, pinnated leaves, with bijugated partial lobes or wings, having the inner ones the least, eagh leaf on a long foot-stalk; and at the sides and ends of the branches many purple flowers in roundish heads; succeeded by broad, flat, jointed pods, in -radiated clusters. This is somewhat of the humble sensitive kind: the leaves, foot-stalks and all, receding from the touch, though not with such facility as in some of the following sorts. The bashful humble plant rises with an under shrubby, prickly stem, branching two or three feet round, armed with hairy spines: by the least touch the leaves instantly recede, contract, close, and, together with the foot-stalk, quickly decline downward, as if ashamed at the approach of the hand. M. scandens, cacoons, or mafootoo wyth, is frequent in all the upland valleys and woodlands on the north side of Jamaica. It climbs up the tallest trees, and spreads itself in every direction, by means of cirrhi, or claspers, so as to form a complete arbour, and to co- wer the space of an English acre from one root. The pod is perhaps the largest and longest in the world; being sometimes eight or nine feet in length, five inches broad, jointed, and con- taining ten or fifteen seeds. M. catechu, according to M. Ker, grows only twelve feet in height, and to one foot in diameter. From this tree, which grows plentifully on the mountainous !, parts of Indostan, where it flowers in June, is produced the officinal drug long known in Europe by the name of terra japo- 69. nica. The true Egyptian acacia rises to a greater height than the preceding. The fruit is a long pod resembling that of the lupin, and contains many flattish brown seeds. It is a native of Arabia and Egypt, and flowers in July. Although the mi- mosa nilotica grows in great abundance over the vast extent of Africa, yet gum arabic is produced chiefly by those trees which are situated near the equatorial regions; and we are told that in Lower Egypt the solar heat is never sufficiently intense for this purpose. The gum exudes in a liquid state from the bark of the trunk and branches of the tree, in a similar manner to the gum which is often produced upon the cherry trees, &c. in this country ; and by exposure to the air it soon acquires soli- dity and hardness. - - MINA, in Grecian Antiquity, a money of account, equal to a hundred drachms. - - - MINE, in Natural History, a place under ground, where metals, minerals, or even precious stones, are dug up. As, therefore, the matter dug out of mines is various, the mines themselves acquire various denominations, as gold mines, sil- ver mines, copper mines, iron-mines, diamond mines, salt mines, mines of antimony, of alum, &c. Mines, then, in gene- ral, are veins or cavities within the earth, whose sides receding from, or approaching nearer to, each other, make them of un- equal breadths in different places, sometimes forming larger spaces which are called holes, they are filled with substances, which, whether metallic or of any other nature, are called the lodes; when the substances forming these lodes are reducible to metal, the lodes are by the miners said to be alive ; other- wise they are called dead lodes. In Cornwall and Devon, the lodes generally hold their course from eastward to westward; though in other parts of England they frequently run from north to south. The sides of the lode never bear in a perpendicular, but constantly under-lay, either to the north or to the south. The lode is frequently intercepted by the crossing of a vein of earth, or stone, or some different metallic substance, in which case it generally happens that one part of the lode is moved a considerable distance to one side. This transient lode is by the miners called flooking; and the part of the lode which is to be moved is said to be heaved. According to Dr. Nichol's observations upon mines, they seem to be, or to have been, the channels through which the waters pass within the earth, and, like rivers, have their small branches opening into them in all directions. Most mines have streams of water running through them; and when they are found dry, it scems to be owing to the waters having changed their course, as being obliged to it, either because the load has stopped up the ancient passages, or that some new and more easy ones are made. Many mines have been discovered by accident; a torrent first laid open a rich vein of the silver mine at Friburg in Germany; sometimes a violent wind, by blowing up trees, or overturning the parts of rocks, has discovered a mine; the same has happened by vio- lent showers, earthquakes, thunder, the firing of woods, or even the stroke of a ploughshare or horse's hoof. The principal signs of a latent metallic vein seem reducible to general heads, such as, 1. The discovery of certain mineral waters. 2. The dis- coloration of the trees or grass of a place. 3. The finding of - pieces of ore on the surface of the ground. 4. The rise of warm exhalations. 5. The finding of metallic sands, and the like. All which are so many encouragements for making a stricter search near the places where any thing of this kind ap- pears; whence rules of practice might be formed for reducing this art to a greater certainty. But when no evident mark of a mine appears, the skilful mineralogist usually bores into the earth, in such places as from some analogy of knowledge gained by experience, or by observing the situation, course, or nature of other mines, he judges may contain metal. After the mine is found, the next thing to be considered is whether it may be dug to advantage. In order to determine this, we are duly to weigh the nature of the place, and its situation as to wood, water, carriage, healthiness, and the like, and compare the result with the richness of the ore, and the charge of dig- ging, stamping, washing, and smelting. Particularly, the form and situation of the spot should be well considered. A mine must either happen, i. In a mountain. 2. In a hill. 3. In a valley. Or 4. In a flat. But mountains and hills are dug with much greater ease and convenience, chiefly because the drains 8 H 670. M. I. N. ſºſ I N ° DICT10NARY OF MECHANICAL scIENC E. # and burrows, that is, the adits or avenues, may be here readily cut-out, both to drain the water, and to form gangways for bring- ing out the ore, &c. In all the four cases, we are to look out for the veins, which the rains or other accidental thing may have laid bare ; and if sueh a vein be found, it may often be proper to open the mine at that place, especially if the vein prove tolerably large and rich; otherwise the most commodious place for situation is to be chosen for the purpose, viz. neither on a flat, nor on the tops of mountains, but on the sides. The best situation for a mine, is a mountainous, woody, wholesome spot, of a fine easy ascent, and bordering on a navigable river. Mine, in the Military art, denotes a subterraneous canal or passage, dug under the wall or ramparts of a fortification, intended to be blown up by gunpowder. The alley or passage of a mine is commonly about four feet square; at the end of this is the chamber of the mine, which is a cavity of about five feet in width and in length, and about six feet in height; and here the gunpowder is stowed. The saucisse of the mine is the train, for which there is always a little aperture left. Two ounces of powder have been found, by experience, capable of raising two cubic feet of earth; consequently, 200 ounces, that is, 12 pounds 8 ounces, will raise 200 cubic feet, which is only 16 feet short of a cubic toise, because 200 ounces, joined toge- ther, have proportionally a greater force than two ounces, as being an united force. All the turnings a miner uses to carry on his mines, and through which he conducts the saucisse, should be well filled with earth and dung; and the masonry in proportion to the earth to be blown up, as 3 to 2. The entrance of the chamber of the mine ought to be firmly shut with thick planks, in the form of a St. Andrew’s cross, so that the enclo- sure be secure, and the void spaces shut up with dung or tem- pered earth. If a gallery be made below or on the side of the chamber, it must absolutely be filled up with the strongest masonry, half as long again as the height of the earth; for this gallery will not only burst, but likewise obstruct the effect of the mine. The powder should always be kept in sacks, which are opened when the mine is charged, and some of the powder strewed about: the greater the quantity of earth to be raised is, the greater is the effect of the mine, supposing it to have the due proportion of powder. Powder has the same effect upon masonry as upon earth, that is, it will proportionally raise either with the same velocity. The branches which are carried into the solidity of walls do not exceed three feet in depth, and two feet six inches in width nearly : this sort of mine is most excellent to blow up the strongest walls. If, when the mincs are made, water be found at the bottom of the chamber, planks are laid there, on which the powder is placed either in sacks or barrels of 100 lb, each. The saucisse must have a clear pas- sage to the powder, and be laid in an anget, or wooden trough, through all the branches. When the powder is placed in the chamber, the planks are laid to cover it, and others again 8 CTOSS these, then one is placed over the top of the chamber, which is shaped for that purpose; between that and those which cover the powder, props are placed, which shore it up ; some inclining towards the outside, others to the inside of the wall; all the void spaces being filled with earth, dung, brick, and rough stones. Afterwards planks are placed at the en- trance of the chamber, with one across the top, whereon they buttress three strong props, whose other ends are likewise propped against another plank situated on the side of the earth in the branch; which props being well fixed between the planks with wedges, the branch should then be filled up to its entrance with the forementioned materials. The saucisses which pass through the side branches must be exactly the same length with that in the middle, to which they join: the part which reaches beyond the entrance of the mine is that which conveys the fire to the other three ; the saucisses being of equal length, will spring together. From a great number of experiments, it appears, l. That the force of a mine is always towards the weakest side; so that the disposition of the chamber of a mine does not at all contribute to determine this effect. 2. That the Quantity of powder must be greater or less, in proportion to the greater or less weight of the bodies to be raised, and to their greater or less cohesion; so that you are to allow for each cubie fathom of loose earth, 9 or fo Ib.; firm earth and streng sand, 11 or 12 lb.; flat clayey earth, 15 or 16 lb.; new masonry, not strongly bound, 15 or 20 lb.: old masonry, well bound, 25 or 30 lb. , 3. That the aperture, entonnoir, of a mine, if rightly charged, is a cone, the diameter of whose base is double the height, taken from the centre of the mine. , 4. That when the mine has been overcharged, its entonnoir is nearly cylindrical, the diameter of the upper extreme not much ex- ceeding that of the chamber. 5. That besides the shock of the powder against the bodies it takes up, it likewise crushes all the earth that borders upon it, both underneath and side- ways. To charge a mine so as to have the most advantageous effect, the weight of the matter to be carried must be known; that is, the solidity of a right cone, whose base is double the height of the earth over the centre of the mine: thus, having found the solidity of the cone in cubic fathoms, multiply the number of fathoms by the number of pounds of powder neces- sary for raising the matter it contains; and if the cone con- tains matters of different weights, take a mean weight between them all, always having a regard to their degrees of cohesion. As to the disposition of mines, there is but one general rule, which is, that the side towards which one would determine the effect to be the weakest; but this varies according to occa- sions and circumstances. The calculation of mines is gene- rally built upon this hypothesis, that the entonnoir of a mine is the frustum of an inverted cone, whose altitude is equal to the radius of the excavation of the mine, and the diameter of the whoſe lesser base is equal to the line of least resistance; and though these suppositions are not quite exact, yet the calcu- lations of mines deduced from them, have proved successful in practice; for which reason this calculation should be followed, till a better and more simple be discovered. M. de Valliere found that the entonnoir of a mine was a paraboloid, which is a solid generated by the rotation of a semiparabola about its axis; but as the difference between these two is very insigni- ficant in practice, that of the frustum of a cone may be used. Coal MiNe. A subterraneous excavation, from which coal is dug. The most extensive coal mines in this island are in the north of England and in Scotland. The descent to the Whitehaven mines is through spacious galleries hewn out of the rock; all the coal being cut away except large pillars, which, in deep parts of the mine, are three yards high, and about twelve yards square at the base; such great strength being there required to support the ponderous roof. These are the deepest coal mines that have been hitherto wrought ; and, perhaps, no other miners have penetrated to so great a depth below the sea as those of Whitehaven; the very deep mines in Hungary, Peru, and elsewhere, being situated in mountainous regions, where the surface of the earth is elevated to a great height above the level of the ocean. There are here three strata of coal, which lie each at a considerable distance ahove the other, and there is a communication by pits between one of these parallel strata and another. But the vein of coal is not always regularly continued in the same inclined plane, but instead thereof, the miners meet with hard rock, which interrupts their further progress. At such places there seem to have been breaks in the earth, from the surface downwards; and in some of them it may have sunk ten or twenty fathoms, or even more. These breaks the miners call dykes ; and when they meet with one of them, their first care is to discover whether the strata in the part adjoining be higher or lower than in the part where they have been working; or, to use their own terms, whether the coal be cast down or up. If it be cast down, they sink a pit to it; but if it be cast up to any consi- derable height, they are oftentimes obliged, with great labour and expense, to carry a level and long gallery through the rock, until they again arrive at the strata of coal. Those who have the direction of these deep and extensive works are obliged, with great art and care, to keep them continually ventilated with per- petual currents of fresh air. In the deserted works, which are not ventilated with perpetual currents of fresh air, large quantities of damps and noxious exhalations are frequently collected; and in such works they often remain for a long time, without doing any mischief. But when by some accident they are ignited, that is to say, set on fire, they then produce dreadful explo- sions, and, bursting out of the pits with great impetuosity, like the fiery eruption from burning mountains, they force along with them ponderous bodies to a great height in the air. The M In M I N 671 DictionARY of MECHANICAL séIENCE. coal in these mines has several times been ignited by these fulminating damps, and has continued burning for many months, until large streams of water were conducted into the mines, and suffered to fill those parts where the coal was burning. By such fires several collieries have been totally destroyed, of which there are instances near Newcastle, and in other parts of England, as well as in Fifeshire. Professor Jameson, in his recent geological work, has scien- tifically described the different varieties of coal by several spe- cies and numerous sub-species; we shall here give such a description of them in regard to their practical uses, as di- .vided into three kinds, according to their degree of inflamma- bility. The least inflammable are Welsh Coal, Irish, and Kil- keny coal ; and blind, or deaf coal, found in many parts of England, Scotland, America, and elsewhere. The last men- ...tioned coal requires a considerable degree of heat to ignite it; but, when once kindled, its combustion lasts a long time: it remains in distinct pieces in the fire without caking, producing neither flame nor smoke, making no cinder, but leaving a stony slag; it makes a hot, glowing fire, like coals or cinders, emit- ting a suffocating effluvia which renders it unfit for burning in dwelling houses, &c. We think it might be used very advan- tageously in distilleries; as the ebullition of the liquid might be more easily regulated than with the flaming coal—a circum- stance of the utmost importance to the quality of the spirit when distilled by naked fire. Open burning coal soon kindles, making a hot, pleasant fire, but is soon consumed, and producing both flame and smoke in abundance; it lies open in the fire, and does not cake together to form cinders, its surface being burnt to ashes before it is thoroughly calcined in the middle, leaving only a white ash. Of this kind is cannel coal, jet, peacock, splint, and most of the coals in the Staffordshire coal district and in Scotland. Close burning coal kindles quickly, makes a very hot fire, melts, and runs together like bitumen ;-it makes a more dura- ble fire than any other coal, and burns finally to ashes of a brownish colour. Of this kind are the Newcastle coal and many others. The open burning and the close burning coal, mixed together, make a more profitable fire for domestic uses than either of them separately. The various kinds of coal are often found mixed with each other under ground; and some of the finer sorts run, like veins, between those of a coarser. This natural admixture is often laid, erroneously, to the charge of the coal merchant, by persons unacquainted with the circum- Stance. - . In the plate, fig. 1 represents a section of the Bradley mine, near Bilston in Staffordshire, exhibiting at the same time the various operations of the miners. A, the whimsey or steam engine, for raising the coal from the bottom of the shaft. B, The banksman. C, one of the shafts of the mine. D, a pas- sage from one shaft to the other. E, the gateway, which is the first work of the miners after the shaft is sunk; it is made from eight to ten feet in height, nine feet wide, and is carried to the whole extent of the work. F, the bolt hole made to cause a free circulation of air through the mine, should any part of which take fire, the bolt hole is built up. G, pillars left in working the ten yard coal, to support the superjacent strata. H, an excavation, called by colliers a stall, who, after the gateway is made, begin thus to work the coal, or hole under. I, the rib, through which the air-way is cut. J, the lights. - c rakes the gateway. L, M, N, miners, heading, holing, and shovelling out the slack or small coal. O, slack carrier. P, a miner working on a scaffold. Q, the spern, a small piece of coal left as a support to many tons above, which fall when this is taken away. R, a collier on a scaffold, taking out the spern as far as he can reach with a pick. S, a collier standing upon a heap of slack, called the gob, with a prong used for that work, which cannot with safety be done with a pick. T, a collier breaking or turning out coal. U, a collier loading a skip. V, a collier breaking the large coal with a wedge. W, a driver with an empty skip. X, a driver with a loaded skip. Y, a skip being drawn up the shaft by the engine. Z, a pillar cal- ed the man of war, which is left to support the upper strata un- til the lower are worked; it is then taken away and the upper coal falls down. - - K, a man who hangs on the skips and | The rope or chain by which the loaded skip Y is drawn up, passes round a wheel worked by the steam-engine, and returns to the other shaft of the mine (not shewn in our engaving) where it lets down an empty skip, which is immediately releas- ed on its arrival at the bottom, and a loaded skip hooked on, to be drawn up as the one shewn descended when empty. It is an astonishing and highly amusing sight to a stranger, in the neighbourhood of Birmingham, and in other coal and iron dis- tricts, to behold at a single coup d'oeil, a vast number of steam engines, with all their massive machinery and apparatus, simul- taneously at work in the open air; some employed in drawing up the iron ore, others coals; which, as they emerge from the earth, are sometimes lifted upon an elevated rail road, from whence, by their own gravity, or by the aid of machinery, they are at once conveyed with the rapidity of lightning, and thun- dering in their progress to their destination the contents in- stantly discharged, and the emptied skip bronght back (by the advance of another that is loaded) to the mouth of the shaft, again to descend into the bowels of the earth to be re-loaded, in endless succession. The effect of this scene at night is be- yond our feeble power of description, it is in every respect a moving scene; the numerous coke works just give sufficient light to see indistinctly all that is going forward, while the fre- quent flashing of a more intense light from Qther sources give a playfulness to the shadows, which picture, to the mind a vast multiplication of objects. 'w The different strata that are cut through to arrive at the prin- cipal bed of coal, are exhibited on the left of the shaft, by va- riously shaded portions of the solid earth, which in Bradley mine are as follow :— FT. IN. FT. IN. 1. Soil on the surface, 1 6 26. Ironstone, ........ 1 5 2. Clay and ratch, .... 9 0 , 27. Rock binds with 3. Clunch, . . . . . . . . . . . 2 6 ironstone, ........ 10 0 4. Ironstone, . . . . . . . . 0 23 28. Dark earth and 5. Clunch,........ . . . . 2 0 ironstone, ........ 6 0 6. Ironstone, . . . . . . . . 0 2 || 29. Rock binds with 7. Soft clay, . . . . . . . . 0 2 ironstone, . . . . . . . . 9 0 8. Dark batty clunch, 3 0 || 30. Peldon,...... . . . . 4 0 9. Gray jointy rock, .. 4 0 || 31. Gray rock, ...... 23 0 10. Ironstone, ........ 0 13 || 32. Dark clunch, .... 2 0 11. Rockbinds mixed with ironstone, .. 4 0 THE MIN E. 12. Soft parting, ...... 0 1 || 33. White coal, ...... 3 () 13. Strong black rock, 4 0 || 34. Tow coal, ........ 2 3 14. Dark clunch, . . . . . . 7 0 || 35. Benches and bras- 15. Ironstone, . . . . . . . ... O 5 sils, . . . . . . . . . . . . . 4 6 16. Dark clunch, with 36. Foot coal, . . . . . . . . 2 3 measures of iron- 37. Slip batt, . . . . . . . . 2 3 - Stone, . . . . . . . . . . . . 5 0 || 38. Slips,. . . . . . . . . . . . 2 3 17. Dark clunch with 39. Stone coal parting, 0 4 ditto. . . . . . . . . . . . . 0 10 | 40. Stone coal and 18. Soft clay, . . . . . . . . . 1 8 patchels, ........ 4 6 19. Batt, ... ... . . . . . . . 2 3 || 41. Penny coal,...... 0 6 20. Brooch coal, . . . . . . 3 6 || 42. Springs and slipper 4 6 21. Fire clay, .......... 0 4 || 43. Humphrey batt, ... 0 4 22. Black ironstone, ... 0 1 44. Humphreys, ...... 2 3 23. Black earth, ....... 1 6 | 24. Ironstone,... . . . . . . 0 2 Depth to the bottom 25. Black earth and the shaft, . . . . . . . . 139 4 ironstone, . . . . . . . . . 1 6 In other mines (and probably in this at a greater depth) a single stratum will sometimes occur, of from 100 to 200 feet in thickness, with very little difference throughout the whole mass. The strata is represented in Bradley mine as nearly horizontal, but this is seldom the case, the strata lying gene- rally in an inclined position to the horizon, which is called by the miners the dip. In consequence of this dip or descent, most of our mines have been commenced working near to the surface of the earth, and as the coal has been cleared away, the mining progressively goes on deeper and , deeper. At Newcastle many of the mines extend to a considerable dis- tance. At Whitehaven the coal works are extended more than a mile under the sea, and at between 600 and 700 feet below. its bottom; and it has been observed generally, that the coals 672 M I N M I N DICTIONARY of MechANICAL science. \ at the greatest distance under the sea are the best in quality,+ hence the distinguishing term sea coal. - Plan of the Workings of a Coal Mine, near Newcastle-upon- Tyne.—The extensive collieries in the vicinity of Newcastle are preserved from the disastrous consequences which attend the accumulation of the fire-damp, or hydrogen gas, by a com- plicated and expensive system of ventilation. The following sketch represents, on a small scale, the plan which is pursued to counteract the effects of that fatal evil, and to spread throughout the workings a sufficient quantity of fresh air. The coal is worked in narrow passages called boards and head- ways; and the dark parts in the plan represent the pillars of coal left to support the roof. There are, generally, two descents to the mine, or more, which are distinguished by the º terms of the upcast or downcast shafts. A, is the downcast shaft by which the air descends, and which is usually assisted by another shaft connected with it; the current of air is repre- sented by the waved line, which is carried through the main passages only, the sub-ways which diverge from them being stopped up by brattices, as a and b, and its motion is acce- lerated by the heat of a large furnace situated at the bottom of the upcast shaft B, and thus the air, after traversing the whole of the workings, ascends the shaft B. What is technically called the choak damp is not of so dan- gerous a character as the fire damp, its presence being more easily ascertained, as it immediately extinguishes the lights; it has the effect of preventing animal respiration. During gales of wind, or when the atmosphere is particularly dense, the ventilation of the mines is attended with more difficulty, and frequently in those exigencies the men are obliged to strike off work.--It is obvious that the above system of ventilation is attended with great labour and expense, not only from the number of hands employed to superintend the wastes and workings of the mine, but from the quantity of brattices which are incessantly required to stop the new ways, and where a communication must be held with the interior of the colliery. Doors at various distances are made, at each of which is placed a boy to permit the ingress and egress of the corves or baskets which contain the coal; the least negligence in closing one of these doors might be attended with serious consequences, as by changing the route of the current of air, and thus leaving unventilated a certain district of the mine, the hydrogen gas would accumulate, and upon the introduction of a candle im- mediately explode; from this circumstance many accidents have arisen, as no caution had been considered necessary where no danger was apprehended. MINERAL WATERS. See WATERs. MINERALOGY, is that science which treats of the solid and inanimate materials of which our globe consists; and these are usually arranged under four classes: the earthy, the saline, the inflammable, and the metallic, which are thus distinguished: 1. The earthy minerals compose the greater part of the crust of the earth, and gencrally form a covering to the rest. They are not remarkable for being heavy, brittle, or light-coloured. They are little disposed to crystallize, are uninflammable in a low temperature, insipid, and without much smell. 2. The saline minerals are commonly moderately heavy, soft, sapid, and possess some degree of transparency. 3. The inflammable class of minerals is light, brittle, mostly opaque, of a yellow, brown, or black colour, seldom crystallize, and never feel cold. 4. Metallic minerals are characterized by being heavy, generally opaque, tough, malleable, cold, not easily inflamed, and by exhibiting a great variety of colours, of a peculiar lustre. Un- der each of these classes are various genera, species, sub- species, and kinds, which it would far exceed the limits of our Pictionary to notice, and which are only properly described in very voluminous works on this particular branch of science. See Geology. We shall describe the external characters, which are of the first importance in facilitating our acquaintance with minerals. These are either generic or specific. The generic are certain properties of minerals, without any reference to their differences, as colour, lustre, weight, &c.; and the differ- ences between these properties form the specific characters. Generic characters may be general or particular. In the first division are comprehended those that occur in all minerals, in the last those that are found only in particular classes of mine- rals. The particular generic external characters are thus advantageously arranged: 1. Colour. 2. Cohesion of particles distinguished into solid, friable, and fluid. In solid minerals are to be regarded the external shape, the external surface, and the external lustre. When broken, the lustre of the frac- ture, the fracture itself, and the shape of the fragments, are to be noticed. In distinct concretions, regard must be paid to the shape of the concretions, their surface, their lustre, trans- parency, streak, and soiling. All these may be ascertained by the eye. By the touch, we may discover the hardness of minerals, their tenacity, frangibility, flexibility, their unctu- osity, coldness, weight, and their adhesion to the tongue. By the ear we distinguish their sound, and by the smell and taste the qualities which these two senses indicate. In friable mine- rals, external shape, lustre, aspect of particles, soiling, and degree of friability, are to be attended to. In fluid minerals, the lustre, transparency, and ſluidity, are principal objects to be regarded. The specific external characters of minerals are founded on the distinctions and varieties of the two great generic divisions. And first, of colours, the names of which are derived from certain bodies in which they most generally occur, either in a natural or artificial state, or from different mixtures and compositions of both. I. Colour.—1. White. This may be snow-white, reddish- white, yellowish-white, silver-white, grayish-white, greenish- white, milk-white, or tin-white. 2. Gray. Lead-gray, bluish- gray, pearl-gray, reddish-gray, smoke-gray, greenish-gray, yellowish-gray, steel-gray, and ash-gray. 3. Black. Grayish- black, brownish-black, dark-black, iron-black, greenish-black, and bluish-black. 4. Blue. Indigo-blue, Prussian-blue, laven- der-blue, smalt-blue, sky-blue. 5. Green. Verdigris-green, celaden-green, mountain-green, emerald-green, leek-green, apple-green, grass-green, pistachio-green, asparagus-green, olive-green, blackish-green, canary-green. 6. Yellow. Sul- phur-yellow, lemon-yellow, gold-yellow, bell-metal-yellow, straw-yellow, wine-yellow, Isabella-yellow, ochre-yellow, orange-yellow, honey-yellow, wax-yellow, brass-yellow. 7. Red. Morning-red, hyacinth-red, brick-red, scarlet-red, copper-red, blood-red, carmine-red, cochineal-red, crimson-red, columbine- red, flesh-red, rose-red, peach-blossom-red, cherry-red, brown- ish-red. 8. Brown. Reddish-brown, clove-brown, hair-brown, yellowish-brown, tombac-brown, wood-brown, liver-brown, blackish-brown. Besides these distinctions, colours may be clear, dark, light, or pale; they may have a tarnished appear- ance, a play, a changeability, an iridescent, an opalescence, a permanent alteration, and a delineation of figure or pattern, such as dotted, spotted, clouded, flamed, striped, veined, den- dritic, or uniform. - II. Cohesion of Particles.—Minerals are divided into, 1. Solid, or such as have their parts coherent, and not easily moveable; 2. Friable, or that state of aggregation in which the particles may be overcome by simple pressure of the finger; and, 3. Fluid, or such as consist of particles which alter their place in regard to each other by their own weight. - 1. Solid Minerals.-External aspect has three things to be regarded, 1. The shape; 2. The surface; and, 3. The lustre. The external shape again may be common, particular, regular, or extraneous; and hence arises the specific differences. 1. M I N M I N 673 Diction ARY of MECHANICAL SCIENCE. The common external shape may be massive, disseminated coarsely, minutely, or finely ; in angular pieces, sharp-cornered or blunt-cornered ; in grains, large, coarse, small, fine, angular, flat, round; in plates, thick or thin ; in membranes or flakes, thick, thin, or very thin. The particular external shape may be longish, as dentiform, filiform, capillary, reticulate, dendri- tic, coralliform, stalactitic, cylindrical, tubiform, claviform, or fruticose ; roundish, as globular, spherical, ovoidal, spheroidal, amygdaloidal, botryodal, reniform, tuberose, or fused-like ; flat, as specular, or in leaves; cavernous, as cellular in various forms, with impressions, perforated, corroded, amorphous, or vesicular; entangled, as ramose, &c. In the regular external shape or crystallization are to be regarded its genuineness, according to which it may be either true or supposititious ; its shape, made up of planes, edges, angles, in which are to be observed the fundamental figure and its parts, the kind of fundamental figure, the varieties of each kind of fundamental figure with their accidents and distinctions, and the alterations which the fundamental figure undergoes by truncation, by bevelment, by acumination, or by a division of the planes. There are a variety of figures under each of these sub-divisions. It must be remarked also that the external shape may be ex- traneous, or derived from the animal and vegetable kingdoms, as in fossils and petrifications. 2. The external surface con- tains several varieties of distinctions. It may be uneven, gra- nulated, rough, smooth, or streaked in various ways and direc- tions. 3. The external lustre is the third generic external character, and is of much importance to be attended to. In this we have to consider the intensity of the lustre, whether it is splendent, Shining, glistening, glimmering, or dull; next the sort of lustre, whether metallic or common. The latter is dis- tinguished into semi-metallic, adamantine, pearly, resinous, and vitreous. Aspect of the Fracture of Solid Minerals.—After the external aspect, the fracture forms no inconsiderable character in mine- rals. Its lustre may be determined as in the external lustre; but the fracture itself admits of great varieties. It may be compact, splintery, coarsely splintery, finely splintery, even, conchoidal, uneven, earthly, hackly. If the fracture is fibrous, we are to consider the thickness of the fibres, if coarse or deli- cate, the direction of the fibres, if straight or curved; and the position of the fibres, if parallel or diverging. In the radiated ſracture we are to regard the breadth of the rays, their direc- tion, their position, their passage or cleavage. In the foliated fracture, the size of the folia, their degree of perfection, their direction, position, aspect of their surface, passage or cleavage, and the number of cleavages, are to be noted. The shape of the fragments may also be very various, regular, as cubic, rhom- boidal, trapezoidal, &c., or irregular, as cuneiform, splintery, tabular, indeterminately angular. . t Aspect of the distinct Concretions.—The aspect of the dis- tinct concretions forms very prominent external characters. They may be granular, different in shape, or in magnitude; they may be lamellar, distinct, concretious, differing in the direction of the lamellae, in the thickness, with regard to shape, and in the position. The surface of the distinct concretions may be smooth, rough, streaked, or uneven; as for their lustre, it may be determined in the same manner as the external lustre. - - - General Aspect as to Transparency.—Minerals, as is well known, have different degrees of transparency, which may be considered among their external characters. They may be transparent, semitransparent, translucent, translucent at the edges, or opaque. - The Streak.-The colour of this external character may be either similar or different. It is presented to us when a mine- ral is scraped with the point of a knife; and is similar, when the powder that is formed is of the same colour with the mine- ral, as in chalk; or dissimilar or different, as in cinnabar, orpi- ment, &c. - The Soiling or Colouring—Is ascertained by taking any mi- neral substance between the fingers, or drawing it across some other body. It may soil strongly, as in chalk : slightly, as in molybdena; or not at all, which is a quality belonging to most of the sulid minerals. All the preceding external characters are recognized by the eye. . 69. External Characters from the Touch.-These are eight in number, and are not destitute of utility to the mineralogical student. 1. Hardness; 2. Tenacity; 3. Frangibility; 4. Flexi- bility; 5. Adhesion to the tongue; 6. Unetuosity; 7. Coldness; 8. Weight. Hardness may be tried by a capacity to resist the file, yielding a little to it, by being semi hard, soft, or very soft. Tenacity has different degrees, in substances being brittle, sec- tile or mild, or ductile. The frangibility consists in minerals being very difficultly frangible, easily frangible, or very easily frangible. The flexibility is proved by being simply flexible, elasticly flexible, commonly flexible, or inflexible. The adhe- sion to the tongue may be strongly adhesive, pretty strongly, weakly, very weakly, or not at all. Unctuosity may be meagre, rather greasy, greasy, or very greasy. Coldness is subdivided into cold, pretty cold, rather cold. Weight may be distinguished into swimming or supernatant, light, rather light, heavy, very heavy. The three last divisions from the touch, are in the Wernerian system regarded as anomalous; but they seem pro- perly to be classed under this head. - - - External Characters from the Sound or Hearing.—The diffe- rent kinds of sound which occur in the mineral kingdom are, 1. A ringing sound, as in native arsenic and thin splinters of horn- stone; 2. A grating sound, as in fresh-burnt clay; 3. A creek. ing sound, as that of natural amalgam. . - 3. 2. Friable Minerals.-The external characters drawn from minerals of this class, are derived, first, from the external shape, which may be massive, disseminated, thinly coating, spumous, or dentritic: secondly, from the Justre, regarded under its intensity, whether glimmering or dull, and its sºrt, whether common glimmering or metallic glimmering ; thirdly, from the aspect of the particles, as being dusty or scaly: fourthly, from soiling or colouring, as strongly or lightly; and lastly, from the friability, which may be loose or cohering. 3. Fluid Minerals.-Of external characters drawn from fluid minerals, there are only two kinds, which include three varie- ties: 1. The lustre, which is either metallic, as in mercury; or resinous, as in rock oil. 2. The transparency, which is trans- parent, as in naphtha ; turbid, as in mineral oil; or opaque, as in mercury. 3. The fluidity, which may be fluid, as in mercury; or viscid, as in mountain tar. . Lxternal Characters from the Smell.—These may be spon- taneously emitted and described as bituminous, faintly sulphu- rous, or faintly bitter; or they may be produced by breathing on, and yield a clay-like smell; or they may be excited by fric- tion, and smell urinous, sulphureous, garlic-like, or empyreu- matic. External Character from the Taste.—This character prevails chiefly in the saline class, and it contains the following varie- ties: a sweetish taste, sweetish astringent, styptic, salty bitter, salty cooling, alkaline, or urinous. Having now given a synoptical view of the external charac- ters of minerals, we shall proceed to their classification, and in this we shall chiefly follow the names and arrangement of Pro fessor Jameson. - - . CLAss I. Earthy Fossils.-Genus I. Diamond. This pre- cious stone has great variety of shades, exhibiting a beautiful play of colours. It occurs in angular and spherical grains, which present planes of crystallization, or are actually crystal- lized. Its fundamental crystal is the octahedron, which passes into various forms. It is hard, brittle, frangible, and has a . specific gravity of 3.600. The diamond has, by modern experi- ments, been proved to be nearly pure carbon, and begins to burn at 14 deg. or 15 deg. of Wedgewood. Genus II. Zircon.—Species I, Zircon ; which see. 2, Hya- cinth. A rectangular four-sided prism, flatly acuminated by four planes, set in the lateral edges. Of this figure, however, Several varieties occur. Crystals generally small, and always imbedded: the lateral planes smooth, externally shining : in- ternally splendent and glassy, inclining somewhat to resinous. Genus III. Flint.—Species 1, Chrysoberul. General colour asparagus-green, passing into a variety of allied shades. It exhibits a milk-white light; occurs in roundish and angular grains, which sometimes approach in shape to the cube. It is seldom crystallized; but when in this state, it presents a long six-sided table, having truncated lateral edges, and longi- tudinally streaked lateral planes. The crystals are small, ex- 8 I (674 M I N M I N DICTIONARY OF MECHANICAL SCIENCE. termally shining, and internally splendent. It is hard, brittle;’ not casily frangible, with a specific gravity of 3600: without addition, infusible. 2, Chrysolite. The colour is pistachio- green, of all degrees of intensity : external surface of the crys- tals splendent, internally splendent, and vitreous. 3, Olivine. Generally asparagus-green, of various degrees of intensity. It is found imbedded also in round pieces and grains; when crys- tallized, which is rare, in rectangular four-sided prisms. In- 'ternally shining, varying between glistening and splendent; semitransparent, easily frangible; in a low degree hard, and not perticularly heavy. It is nearly fusible without addition. Oc- surs imbedded in basalt. 4, Augite. Colour blackish-green. It occurs chiefly in indeterminate angular pieces and roundish grains, Occasionally crystallized, and presents broad rectan- gular six-sided prisms. The crystals are mostly small. In- ternally the lustre is shining, approaching sometimes to splen- dent. The augite is only translucent, and but faintly transpa- rent. It is hard, not easily frangible, and not particularly heavy. It is found in basalt, either singly, or accompanied with olivine. 5, Vesuviane. Its principal colour is dark olive- green, passing into other allied shades. It occurs massive, and often crystallized in rectangular four-sided prisms. The crystals are mostly short, and placed on one another. The vesuviane is translucent, hard in a moderate degree, and ap- proaching to heavy. Before the blowpipe it melts without addition. it derives its name ; in Siberia and Kamtschatka. 6, Leuzite. In colour yellowish and grayish-white. It occurs mostly in original round and angular grains. It exhibits acute double eight-sided pyramids. Internally it is shining, and approach- ing to glistening, with a vitreous lustre, inclining somewhat to resinous. The leuzite is translucent and semitransparent; hard in a low degree, brittle, easily frangible, and not very heavy. With borax, it forms a brownish transparent glass. It is found in rocks of the newest floetz trap formation, particu- larly in basalt. 7, Melanite. In colour velvet-black. It occurs crystallized in a six-sided prism. The crystals are middle-sized or small. Externally they are smooth and shining, approach- ing to splendent; internally slaining, inclining to glistening. The melanite is opaque, hard, pretty easily frangible, and not very heavy. It occurs imbedded in rocks of the newest floetz trap formation. 8, Garnet ; see GARNet. 9, Pyrope. Colour dark blood-red. It occurs in small and middle-sized, rouridish, and angular grains ; but never crystallized. Its iustre is splendent and vitreous. It is completely transparent, hard so as to scratch quartz. It is found imbedded in Scotland, in sand, on the sea shore. It is employed in various kinds of jewellery, and is generally set in a gold foil. 10. Grenatite. Colour a dark reddish-brown. It is always crystallized in broad six-sided prisms. The crystals small and middle-sized, internally glistening, with a lustre between vitreous and resi- nous. It varies from opaque to translucent, is hard, brittle, easily frangible, and not particularly heavy. It is found im- bedded in mica slate. 11, Spinelle. The predominant colour is red, which passes on into blue, green, yellow, and brown. It occurs in grains, and likewise crystallized in octahedrons, with several variations. Externally and internally the lustre is splendent and vitreous. It is fusible with borax: occurs in rocks belonging to the newest floetz trap formation. It is used as a precious stone. 12, Sapphire. The principal colour Ber- lin blue : but it is found also red, with the intermediate shades of these two colours. It occurs in small rolled pieces, and crystallized in double three-sided pyramids. The crystals are small and middle-sized. Internaliy the lustre is splendent and vitreous. Some varieties, when cut, exhibit a star of six rays. The sapphire is hard in the highest degree, but yields to the diamond : it is easily frangible; specific gravity of about 4'000. It is fusible without addition : occurs in rocks of the newest floetz trap formation. This precious stone is found in the utmost beauty in Pegu and Ceylon. 13, Corundum : see CoRUN- DUM. 14, Diamond Spar. The colour is a dark hair-brown. It occurs massive, disseminated, in rolled pieces, and crystal- lized in six-sided prisms, or very acute six-sided pyramids. Internally, its lustre is splendent: translucent on the edges, hard in a high degree, easily frangible. It has hitherto been found only in China. Both this stone and corundum are em- It is found among the exuviae of Vesuvius, whence. ployed in cutting and polishing hard minerals, and they seem to be nearly allied to each other. 15, Emery; see EM ERY. 16, Topaz." The chief colour is a wine-yellow, of all degrees of intensity. It is found massive, disseminated, and sometimes rolled, but most commonly crystallized in oblique eight-sided or four sided prisms, which exhibit several varieties. The crystals are small and middle-sized, externally splendent; in- ternally splendent and shining; lustre vitreous. The topaz alternates from translucent to transparent, and is duplicating transparent. It is hard in a high degree, easily frangible, and is not particularly heavy. It is fusible with borax; and some kinds in a gentle heat turn white, and are sometimes sold for diamonds. It is commonly found in veins that traverse primi- tive rocks. 17, Emerald ; which see. 18, Beryl ; see BERYl. 19, Schorl. Divided into two sub-species, common schorl and tourmaline. 20, Thumerstone. Colour commonly clove- brown, of various degrees of intensity. It is occasionally found massive, more frequently disseminated: but generally crystal- lized in very flat and oblique rhombs. Externally, its lustre is splendent: internally, it alternates from glistening to shining, and is vitreous. This species alternates from perfectly trans- parent to weakly translucent. It appears to be peculiar to the primitive mountains. 21, Iron Flint. The colour a yellowish- brown, bordering on liver-brown. It occurs commonly massive, but also crystallized in small equiangular six-sided prisms. Externally, its lustre is splendent, internally shining, and is intermediate between vitreous and resinous. It is opaque, and slightly translucent on the edges. It is pretty hard, some- what difficultly frangible, and approaching to heavy. It occurs in iron-stone veins, and renders the ore very difficult of fusion. 22, Quartz. Werner divides this into five sub-species: ame- thyst, rock-crystal, milk-quartz, common quartz, and prase. 23, Hornstone; which see. 24, Flint. Colour gray, but with many varieties. It occurs massive, in regular plates, in angu- lar grains, in globular and elliptical rolled pieces, in the form of sand, and tubercles and perforated. Sometimes it is crys- tallized, in double six-sided prisms, or flat double three-sided pyramids. Internally, the lustre is glimmering, translucent on the edges, hard, easily frangible, and not particularly heavy. 25, Chalcedony. Divided into two sub-species, chalcedony and cornelian; which see. Agate. The fossils known under this name are all compound substances; and hence cannot have a particular place in any systematic arrangement. Wer- ner, therefore, has placed them as a supplement to the species chalcedony, which forms a principal constituent part of them. See AGAT e. 26, Heliotrope; which see. 27, Plasma. The colour intermediate between grass and leek-green, and of dif- ferent degrees of intensity. It occurs in indeterminable angu- lar pieces which have a rough earthy crust. Internally its lustre is glistening. It is intermediate between semi-transpa- rent and strongly translucent, hard, brittle, frangible without great difficulty, and not particularly heavy. 28, Chrysopras. 29, Flinty Slate. This has been divided into two sub-species, com- mon flinty slate and Lydian stone. 30, Cat's Eye. The colour gray, with many varieties. It occurs in blunt-edged pieces, in rolled pieces, and likewise massive. Internally shining; usually translucent, and sometimes also semi-transparent. It is hard, easily frangible, and not particularly heavy. Its geog- nostic situation is unknown. It is imported from Ceylon and the coast of Malabar; and is usually cut for ring-stones. Some of the varieties are highly valued. 31, Prehnite. Colours various shades of green, white, and yellow. It is sometimes massive, and sometimes crystallized in oblique four-sided tables. Externally, the crystals are smooth and shining; internally, inclining to glistening and pearly. It is translu- cent, sometimes passing into semi-transparent, and transpa- rent: it is hard, easily frangible, and not very heavy. 32. Zeolite. This species is divided into five sub-species: 1. Mealy; 2. Fibrous; 3. Radiated ; 4. Foliated ; 5. Cubic-zeolite. 33, Cross-Stone. The colour is a grayish-white. It occurs crys- tallized either in broad rectangular four-sided prisms, or in twin crystals. Internal and external lustre is shining, inclin- ing to splendent or glistening. The cross-stone is translucent, passing to transparent, semi-hard, easily frangible, and not particularly heavy. It has hitherto been found only in mineral veins, and in agate balls. 34, Agate-Stone. Colour a perfect M. I. N M I N , DICTIONARY OF. M. EU HANICA L SCI EN C E. 675 azure blue, of diſſerent shades. It is found massive, dissemi- nated, and in rolled pieces. The lustre is glistering and glim- mering. ..It is translucent on the edges, pretty hard, brittle, easily frangible, and not particularly heavy. See Ag Ate. . Genus IV. Clay.—Species I, Jasper. 2, Opal. 3. Pitch Stone. 4, Obsidian. 5, Pearl Stone. 6, Pumice Stone. 7, Felspar. Di- vided into four sub-species; compact, common, adularia, and Labrador stone. 8, Pure Clay. Snow white, with occasionally a yellowish tinge, it occurs in kidney-shaped pieces, which have no lustre. It is opaque, soils very little, adheres slightly to the tongue, is light, and intermediate between soft and fri- able. Pure clay is found immediately under the soil, accom- panied with foliated gypsum and selenite, at Halle, in Saxony, only. 9, Porcelain Earth. 10, Common Clay. Divided into six sub-species: 1. Loam ; 2. Potters’ clay is of two kinds, earthy and slaty; 3. Pipe clay; 4. Variegated clay, commonly White, red, and yellow, striped, veined, and spotted : it occurs massive, is soft, passing into friable, feels a little greasy, and adheres somewhat to the tongue: 5. Clay-stone, commonly gray or red, with various intermediate tints; 6. Slate clay. 1 1, Polier, or Polishing-stone. 12, Tripoli. 13, Alum Stone. 14, Alum Earth. 15, Alum Slate. 16, Bituminous Shale. 17, Draw- ing Slate, or Black Chalk. Its colour is a grayish-black, with a tinge of blue ; it occurs massive, is opaque, colours and writes, is soft, mild, easily frangible, feels meagre but fine, and is rather light: it is found in primitive mountains in France, Germany, Iceland, Scotland, and the Hebrides. When of a middling. degree of hardness, it is used for drawing. 18, Whet Slate. 19, Clay Slate. 20, Lepidolite. Colour a kind of peach- blossom, it occurs massive. Internal lustre glistening; it is translucent, soft, easily frangible, and easily melts before the blowpipe. Hitherto it has only been found in Moravia, where it lies. in gneiss. 21, Mica, or Glimmer. 22, Pot Stone. 23, Chlorite, which see. 24, Hornblende. 25, Basalt. 26, Wacke. 27, Clink Stone. Commonly of a dark greenish-gray colour, massive, in regular columns, and tabular distirct concretions, usually translucent on the edges, brittle, easili frangible, and when struck with a hammer sounding like a piece of metal. It is said to belong to the floetz trap formation. and generally rests on basalt. 28, Lava. Divided into two sub-species; Stag-lava and Toam-lava. 29, Green Earth. Its colour is a celaden-green, of various degrees of intensity : it occurs mas- sive, in angular and globular pieces, and also disseminated. Internally it is dull, streak glistening, very soft, easily frangible, and light. It is principally found in amygdaloid, in Saxony, Bohemia, Scotland, and other places, and is used by painters. 30, Lithontage. Divided into two sub-species; friable and indurated. 31, Rock Soap. 32, Yellow Earth. To the clay É. likewise, belong adhesive slate, ſloat-stone, pinite, and All II, D.C.]". - - Genus V. Talc —Species 1, Bole. 2, Native Tale Earth. 3, Meerschaum. 4, Fullers’ Earth. 5, Neaphrite. 6, Steatite. 7, Serpentine, which see 8, Schiller Stone. 9, Talc. 10, Asbest. See ASB Estos. 11, Cyanite, which see. 12, Actymolite. Is divided into the following sub-species: 1. Asbestous actymolite is of a greenish-gray colour, occurs massive, disseminated, and in capillary crystals; is internally glistening, translucent on the edges, soft, brittle, not easily frangible, not particularly heavy : it is ſound in mineral beds in Saxony, and other parts of Germany. 2. Common actymolite is generally of a green leek golour, passing into other shades of the same; it occurs massive, and, likewise crystallized in very oblique six-sided prisms, is splendent externally, semi-hard, rather brittle, and inot easily frangible: it is found in beds in primitive mountains, II] Saxony, Switzerland, Norway, and Scotland. 3. Glassy actynolite is principally of a mountain green colour, of Warious degrees of intensity. * Genus VI. Cale.—Species 1, Rock Milk. 2, Chalk. Colour Principally of a yellowish-white: it occurs massive, dissemi- nated, and as crust over ſlint. 3, Lime-stºne. Divided into several sub-species: viz. compact, foliated lime-stone, fibrous lime stone, and pea-stone. 4, Schaum, or I'oaming Earth. 5, Slate spar. 6, Brown spar. 7, Rhomb spar. 8, Schaalstone. 9, Stink-stone. 10, Marle. 11, Bituminous marle slate. Colour intermediate between grayish and brownish-black; it is mas. sive, from glimmering to shining, fragments slaty, usually soft, not very brittle, easily frangible, and streak shining : it is found in beds along with the oldest ſloetz line-stone, and con- tains much copper intermixed with it, on account of which it is usually smelted in Thuringia. 12, Cale tuff. 13, Arragonite. Principal colours are greenish-gray and iron-gray : it occurs crystallized in perfect equiangular six-sided prisms; the lustre is glistening, passing into shining, and is vitreous ; it is semi- hard, brittle, not particularly heavy. It was first discovered in the province of Arragon, whence its name, imbedded in gyps. 14, Appatite. Colours white, green, blue, and red; it generally occurs crystallized, the radical form of which is the equiangular six-sided prism. Externally it is splendent, in- ternally shining and resinous: it is commonly transparent, semi-hard, brittle, easily frangible, and occurs in thin veins, &c. 15, Asparagus, or spargel stone. 16, Boracite. Its colours are yellowish, smoke and grayish-white, passing to asparagus green; it occurs in crystallized cubes, with the edges and angles truncated, internally shining, commonly semi-transpa- rent, semi-hard, brittle, and easily frangible. 17, Flucr. See Fluor. 18, Gyps. This is divided into the following sub- species: 1. Gyps earth, of a yellowish-white colour, passing into some allied shades, is intermediate between fine scaly, and dusky, dull, and feebly glimmering, soils a little, feels meagre but soft and fine, and is light; it is found, though rarely, in gyps countries. 2. Compact gyps, is commonly ash- gray, passing into smoke and yellowish-gray, is massive, in- ternally dull, feebly translucent on the edges, very soft, fran- gible without great difficulty, and is employed in architecture and sculpture, under the name of alabaster. 3. Foliated gyps is commonly white, gray, or red, presenting spotted, striped, and veined colour delineations. 4. Fibrous gyps is principally white, gray, and red, with various shades of each. Gyps, when burnt, forms an excellent cement, and is used for many orna- mental purposes. 19, Selenite. 20, Cube spar. Genus VII. Baryte.—Species 1, Whitherite. 2, Heavy spar or baryte. * • . . Genus VIII. Strontian.—Species 1, Strontian. 2, Celestine. Divided into two sub-species: 1. Fibrous celestine, is of an intermediate colour, between indigo blue and bluish-gray; it occurs massive and in plates, and also crystallized, shewing a tendency to prismatic distinct concretions; it is translucent, soft, or semi-hard, easily frangible, and pretty heavy. 2. Foliated celestine, is of a milky-white colour falling into blue ; it occurs massive, and also crystallized in six-sided tables, intersecting each other; it has a glistening lustre, is strongly translucent, softish, not particularly brittle, easily frangible, and hard. It occurs sometimes in suſphur beds, and is found very finely crystallized in Sicily, and near Bristol. CLAss II. Fossil Salts.—The substances included in this class are confined to those which are found in a natural state only; and the greater part of them appear to be formed by the agency of water, air, &c. The distinguishing characters of fossil salts are, their taste and easy solution. They resemble each other so closely, that the term saline consistence is used to express whatever relates to hardness, tenacity, and frangibility. Species 1, Natron, or natural soda. 2, Natural nitre. 3. Natural rock-salt. 4, Natural sal-ammoniac. 5, Natural Epsom salt. 6, Natural Glauher salt. 7, Natural alum. 8, Hair sait. 9, Rock butter. Colour light yellow, or grayish-white ; it occurs massive and tuberose, is translucent, has a saline con- sistence, a sweetish sour astringent taste, and feels a little greasy. It oozes out of fissures of rocks of alum slate, and is found in Lusatia, Thuringia, Denmark. Siberia, and near Paisley in Scotland. 10, Natural vitriol. Divided into the sub- species: iron, copper, and zinc vitriol. Borax, though so well known by name, is without a place in the Wernerian system, as it is uncertain whether or not it occurs in a solid state ; most probably it occurs only in solution in certain lakes. The new genus stallite, of which only one species, cryolite, has been found in Greenland, comes under this head. º CLAss III. Inflammable Fossils-Fossils belonging to this class are light, brittle, mostly opaque, yellow, brown, or black. seldom crystallized, and never feel cold. They are more nearly allied to the metallic than to the earthy or saline classes. Genus I. Sulphur.—Species 1, Natural sulphur. Genus II. Bituminous-See BITUM EN and CoA L. 676 M. I. N M I N DICTIONARY OF MECHANIC AI, SCIENCE. Genus III. Graphite.—Species 1, Glance coal. Divided into two sub-species: conchoidal and slaty. 2, Graphite, containing two sub-species, scaly and compact graphite. 3, Mineral char- coal. Colour a grayish-black:..it occurs in small angular and somewhat cubical-shaped pieces, is glimmering, with a silky lustre, soils strongly, is soft, and light. It is found in thin layers in different kinds of coal, and is widely disseminated. Genus IV. Resin.—Species 1, Amber; which is divided into º: sub-species: 1. White; 2. Yellow amber. 2, Honey-stone. Mellite. - CLAss IV. Metallic Fossils.-Genus I. Platina. Species 1, Native platina. - - Genus II. Gold,—Species 1, Native gold. Divided into three sub-species: 1. Gold-yellow native gold; 2. Brass-yel- low native yellow ; 3. Grayish-yellow native gold. ... * * Genus III. Mercury.—Species 1, Native mercury, or quick- silver. 2, Natural amalgam. 3, Mercurial horn-ore, or cor- neous mercury. 4, Mercurial liver ore, or mercurial hepatic ore. .5, Cinnabar. Genus IV. Silver.—Species 1, Native silver. 2, Antimonial silver. 3, Arsenical silver, 4, Corneous silver ore, or horn ore. 5, Silver black. 6, Silver glance. 7, Brittle silver glance. 8, Red silver ore. 9, White, silver ore. 10, Black silver ore. Genus V. Copper.—Species 1, Native copper. 2, Copper glance. 3, Variegated copper ore. Colour, when dug, inter- mediate between copper-red and pinchbeck-brown, but it soon becomes tarnished: it occurs massive, disseminated in plates, membranes, and crystallized in octahedrons. 4, Copper pyrites. 5, White copper ore. 6. Gray copper ore, or Fahl ore. Com- mon colour steel-gray : it occurs massive, disseminated, and also crystallized in tetrahedrons, octahedrons, and garnet dodecahedrons. 7, Copper black. 8, Red copper ore. 9, Tile ore. 10, Copper azure. , 11, Melachite. 12, Copper green. Colour verdigris green, of different degrees of intensity. 13, Iron-shot copper green. 14, Copper emerald. 15, Copper miga. Emerald-green colour: it occurs massive, disseminated, and occasionally crystallized in very thin six-sided tables ; it is soft, sectile, not very brittle, nor particularly heavy; and has hitherto been found only in veins in Cornwall, where it passes under the unscientific name of foliatic arseniate of cop- per. 16, Lenticular ore. 17, Olive ore. Mountain blue. Genus VI. Iron—Species 1, Native iron. Is of a light steel- gray colour, inclining to silver-white : it has hitherto been found only ramose ; internally it is intermediate between glimmering and glistening, with a perfect metallic lustre, and a hackly fracture: it is between soft and semi-hard, perfectly malleable, common, flexible, difficultly frangible, and uncom- monly heavy. Hitherto it has been found only in loose masses on the surface of the earth, and is a rare production. 2, Iron pyrites. 3, Magnetic pyrites. 4, Magnetic iron-stone. Com- mon magnetic iron-stone is of an iron black-colour: is mas- sive, disseminated, and also crystallized in cubes, octahedrons, and garnet dodecahedrons, and rectangular four-sided prisms. It is extremely shining ; internally between splendent and glistening, with a metallic lustre; is intermediate between hard and semi-hard, brittle and heavy. It occurs most fre- quently in primitive mountains. When pure it affords most excellent bar iron. 5, Iron glance. Common iron glance is usually of a dark steel gray colour, with several diſſerent shades; it commonly occurs massive and disseminated, and also crystallized in flat, double, three-sided pyramids, and in double three-sided pyramids. It offers, when smelted, an excellent malleable iron. 6, Red iron-stone. Red iron froth. The colour is intermediate between cherry-red and brownish- red ; it occurs commonly friable, massive, sometimes coating and disseminated, and is composed of scaly particles, which are glimmering, and have a semi-metallic lustre. 7, Brown iron-stone. Brown iron froth is of an intermediate colour between steel-gray and clove-brown, and is between friable and solid; it occurs massive, coating, spumous, &c., and is composed of scaly particles, shining and glistening, with a metallic lustre. It soils strongly, feels greasy, and is very light. It is commonly found lining dusty cavities. 8. Sparry iron-$ iOne. which, on exposure to the air or heat, changes into brown or black; it occurs massive, disseminated with pyramidal im- has a metallic lustre. The principal colour is a light yellowish-gray, pressions, in plates, and crystallized. It is chiefly confined to the primitive and floetz mountains. 9, Black iron-stone. 10, Clay iron-stone. Reddle is of a light brownish-red, passing into a cherry-red: it occurs only massive ; sóils strongly, and writes, is sectile, easily frangible, and rather heavy. It is chiefly found in the newer clay-state, in Germany and Siberia. The coarser varieties are used by the carpenter, the finer by the painter, under the name of red chalk. 11, Bog iron ore. 12, Blue iron-earth. 13, Green iron-earth. Friable green iron- earth is of a siskin-green colour; occurs massive and dissemi- nated, is more or less cohering, soft, fine, easily frangible, and intermediate between particularly heavy and heavy. 14, Cube ore. Genus VII. Lead.—Species 1, Lead glance. Common lead glance is of a fresh lead-gray colour, of different degrees of intensity; it occurs massive, disseminated, in membranes, &c., and also crystallized in cubes, octahedrons, four-sided prisms, six-sided prisms, and three-sided tables. It is soft, sectile, externally easily frangible, and uncommonly heavy, and is found in veins and beds in primitive, transitive, and floetz mountains. It is most frequently worked as an ore of lead, but sometimes as an ore of silver. 2, Blue lead ore. 3, Brown lead ore. 4, Black lead ore. 5, White lead ore. 6, Green lead ore. 7, Red lead ore. 8, Yellow lead ore. 9, Lead vitriol, or vitriol of lead. 10, Lead earth. Genus VIII. Tin.—Species 1, Tin pyrites. Cornish tin ore, or wood tin. . Genus IX. Bismuth.-Species 1, Native bismuth. 2, Bis- muth glance, of a light-gray lead-colour. 3, Bismuth-ochre, of a straw-yellow colour passing into other neighbouring shades. Genus X. Zinc.—Species 1, Blende. 2, Calamine. 2, Tin stone. 3, Genus XI. Antimony.—Species 1, Native antimony. 2, Gray, 3, Black. 4, Red. 5, White antimony ore. 6, Anti- mony-ochre. Genus XII. Cobalt.—Species 1, White cobalt ore. 2, Gray cobalt ore. 3, Cobalt glance. The colour is of a silver-white, slightly inclining to reddish: it is commonly massive and dis- seminated, sometimes crystallized in different forms: is exter- nally splendent, internally between shining and glistening, and It is semi-hard, brittle, not very easily frangible ; and when struck with steel, emits an arsenical smell. It is found in veins in various formations, in the dif- ferent mine countries of the continent of Europe; and from it the greatest part of the cobalt in commerce is obtained, which is highly useful in the manufacture of glass, and as a pigment. 4. Black cobalt ore. 5, Brown cobalt ochre. 6, Yellow cobalt ochre. 7, Red cobalt ochre. Genus XIII. Nickel.-Species. 1, Copper nickel. 2, Nickel ochre. • § Genus XIV. Manganese.—The three species are, 1. Gray; 2. Black ; 3. Red manganese ore. - Genus XV. Molybderia.--Species I, Molybdena. Genus XVI. Arsenic.—Species 1, Native arsenic. 2, Arsenic pyrites. 3. Orpiment, 4, Arsenic bloom. . -- Genus XVII. Scheele.—Species 1, Tungsten. 2, Wolfram. Genus XVIII. Menachine.—Species 1, Menachanite. 2, Octahedrite. 3, Rutile. 4, Nigrine. 5, Iserine. Genus XIX. Uran.--Species 1, Pitch ore. 2, Uran mica. 3, Uran ochre. . e Genus XX. Sylvan.—Species 1, Native sylvan. 2, Graphic ore. 3, Yellow sylvan ore. 4, Black sylvan ore. Genus XXI. Chroma.-Species 1, Acicular, or needle ore. Its colour is dark steel-gray: occurs in imbedded acicular crystals; internally shines with a metallic lustre, is soft, not very brittle, heavy, and is always accompanied with chrome ochre, and sometimes with native gold. It is found in Siberia. 2, Chrome ochre. It is of a verdigris green, passing through several neighbouring shades: it occurs massive, disseminated, and in membranes; is dull, soft, not very heavy, and is found with the preceding species. - For the various forms which minerals are found under, see CRYSTALLIZATION. . MINIATURE, a delicate kind of painting distinguished by the smallness of the figures, its being performed with dots or points instead of lines; by the faintness of the colouring; and by its being usually done on vellum. See PAINTING. M. I. N. M 1 N DICTIONARY OF MECHANICAL SCIENCE. 677 MINISTER, in Theology, a person who preaches, performs religious worship in public, administers the sacrament, &c. MIN 1st ER of State, a person to whom a sovereign prince intrusts the administration of the government. e - Minister, Foreign, is a person sent into a foreign country to manage the affairs of his province, or of the state to which he belongs. Of these there are two kinds: those of the first rank are ambassadors and envoys extraordinary, who repre- sent the persons of their sovereigns. The ministers of the second rank are the ordinary residents. MINIUM, in the Arts, red lead and oxide of lead. MINOR, in Law, is an heir, either male or female, before arriving at the age of twenty-one; during their minority, minors are usually incapable of acting for themselves, in a legal point of view. • . . tº MINor, in Logic, the second proposition of a syllogism. MINSTREL, in ancient customs, certain persons who com- bined the character of poet and musician, and whose profes- sion it was to wander about the countries they inhabited, sing- ing panegyrical songs and verses on their occasional benefac- tors, accompanying them with some musical instrument. MINT, the place in which the king's money is coined. See Col NAGE. There were anciently mints in almost every county in England; but the only mint at present in the British domi- mions, is that in the Tower of London. The officers of the mint are, 1. The warden of the mint, who is the chief; he oversees the other officers, and receives the bullion. 2. The master worker, who receives bullion from the warden, causes it to be melted, delivers it to the moneyers; and when it is coined, receives it again. 3. The comptroller, who is the overseer of all the inferior officers, and sees that all the money is made to the just assize. 4. The assay master, who weighs the gold and silver, and sees that it is according to the stand- ard. 5. The two auditors, who take the accounts. 6. The surveyor of the melting, who, after the assay master has made trial of the bullion, sees that it is cast out, and not altered after it is delivered to the melter. 7. The engraver, who engraves the stamps and dies for the coinage of the money. 8. The clerk of the irons, who sees that the irons are clean and fit to work with. 9. The meiter, who melts the bullion before it be coined. 10. The provost of the mint, who provides for and oversees all the moneyers. 11. The blanchers, who anneal and cleanse the money. 12. The moneyers; some of whom forge the money, some share it, some round and mill it, and some stamp and coin it. 13. The porters, who keep the gate of the mint. MINT, was also a pretended place of privilege, in South- wark, near the King’s Bench, put down by statute. If any persons, within the limits of the mint, shall obstruct any officer in the serving of any writ or process, &c. or assault any per- son therein, so as he receive any bodily hurt, the offender shall be guilty of felony, and be transported to the plantations, &c. stat. 9. Geo. I. - - Process of Coining at the Royal Mint.—The process of melting silver, at the royal mint, is a recent invention, and a very great improvement. The usual mode was to melt it into black lead pots, and a considerable coinage of tokens for the Bank of Ire- Iand was performed with the meltings done in this way. The importations being entirely Spanish dollars, and the tokens of that standard, the melter could easily melt them in quantities of 60lbs. troy, which was done. The inconvenience of this mode was severely felt, because ingots of silver of various qua- lities could not be imported for coinage, from the diſficulty of not being able to blend several together in oue pot, so as to produce the proper standard of our money. So sensible was government of this imperfection in the mint, that in the year 1777, Mr. Alchorne, then master’s assay-master, was sent to visit the mints of Paris, Rouen, Lille, and Brussels, and to collect information as to the arts of coining practised in those mints, and particularly the art of melting silver in large quan- tities. Alchorne's intimate knowledge of the English mint, to- gether with his extensive knowledge as a practical chemist, well fitted him for the undertaking ; and his observations on the coin and coinage of France and Flanders are creditable to both his judgment and knowledge. It is worthy of remark, that it is on record in the books of the 70, mint, that in the recoinage of William III. the pots of silver weighed 400 pounds troy and upwards; but every trace as to how this quantity of silver was melted is completely lost; and it is only conjectured that it was done in pots made of wrought iron. But not a vestige of a melting furnace, fitted for such a purpose, is to be found in the Tower, nor a single record of the method then practised. In 1758 some trials for melting silver in wrought iron pots took place, by means of a blast furnace ; but they were found so laborious, inconvenient, and profitless, as to cause the pro- cess to be abandoned. In 1787, when some silver was import- ed into the mint for coinage, new experiments were made by the late deputy master and worker, Mr. Morrison, who con- ducted the meltings. A blast furnace was again tried and abandoned. He hext attempted to melt the silver in large black lead pots, containing from 100 to 120 lbs. troy ; but the repeated breaking of the pots, although it was attempted to guard them by outside luting, proved a great interruption to the business, and serious loss to the melter. Trial, indeed, was made with cast-iron pots, but these were found subject to melt, and the iron got mixed with the silver. The work too was continually stopped by the king's assayer, in consequence of the metal not being of the proper standard, it being always refined by the process of melting, and lading it with ladles from the pot. . Independently of these considerations, great difficulty arose at the office in arranging the potting previous to the operation. The practice pursued at the mint to reduce the metal to stand- ard, of combining and blending the various ingots of better and inferior qualities, adding what little portion of alloy or fine metal might be necessary to obtain accuracy, rendered it impossible, where the ingots weighed from 60 to 80 lbs. troy, to put them of a weight not exceeding 100 lbs. It therefore bo- came necessary, in the first place, to reduce the larger descrip- tion of ingots to a smaller size by melting, and these were again weighed in the office of receipt. Hence a double operation took place, occasioning additional labour, waste, and expense to the melter, and requiring extraordinary trouble and at- tendance on the part of the office. It was very obvious that this mode of conducting the silver meltings was extremely de- fective, and was in consequence abandoned. The next expe- riments made were with a reverberatory furnace, built after the model of those used in the Lille mint. But no better success attended these trials, and the process was, as in former cases, abandoned. The imperfection here arose from the great refine- ment of the silver in the melting, by the oxidation of the alloy, and which the usage of the British mint does not allow the melter to supply, as in the French mints. In the French mints, as soon as the silver is in fusion, a sample is taken out and assayed, and copper is added in the proportion to the refine- ment of the melted silver, (which is kept in fusion while the assay is making ;) the whole is well stirred, and immediately laded out and cast into bars. In 1795 and 1798, several farther trials were made by Morrison, who was indefatigable in his en- deavours to perfect his department, with a view to attain the object so much desired—that of melting large quantities of sil- ver at once, without producing so much waste and refinement in the metal. In these experiments he tried three furnaces, each of a different construction; and though he was much nearer his point, there was still an imperfection, arising from the mode of dipping out the metal from the pot with ladles, which chilled the metal, and rendered the process extremely laborious and tedious. - No new experiments were made until the year 1804. Mr. Morrison having died in 1803, was succeeded by his son in the office of deputy master and worker of the mint. The extreme scarcity and defective state of the silver coin at this time, arising from the defective state of the melting department, urged Morrison to renew the experiments of his father. In following these experiments, Mr. Morrison had in view the construction of a furnace adapted for the use of cast iron pots, the use of pots of a size capable of melting from 400 to 500 lbs. troy, at one charge—the adaption of such machinery as would supersede the clumsy and wasteful process of lading the silver from the pots when melted—and lastly, the introduction of the | use of moulds made of cast-iron, in place of those then used ifi 8 K. M 1 N M. I. N DIGTHoNARY OF MEGHANICAL SCIENGE, the mint, and which were made of sand. In all these objects Mr. Morrison, highly to his credit, perfectly succeeded; and the silver melting department of the new mint was constructed according to the furnace first used in the experiments which led to such a satisfactory result. The whole has been in use since 1811, and the department is capable of melting, with ease, 10,000lbs. troy of silver daily, as was done for several months during the late recoinage (1817). Before we give a description of the apparatus for ſlatting, rolling, or laminating the silver, we shall proceed to describe the machinery and furnaces of the silver melting department. - The engraving illustrative of this article exhibits a perspec- tive view of the machine for casting ingots of silver. . . In the plate, fig. 1, A A are the furnaces in which the metal is melted. These are the air furnaces, built of fire brick, in the usual manner of melting furnaces; but to render them more durable, the brick work is cased in cast-iron plates, which are put together with screws. B B are the covers to the furnace ; ‘they are held down to the top plate of the furnaces by a single screw pin for each; and on the opposite side of the cover, a handle a is fixed. By pushing this handle, the cover is moved sideways upon its centre pin, so as to remove it from the fur- mace mouth. A roller is fitted to the cover, to run upon the top plate and render the motion easy. The interior figure of each furnace is circular, 30 inches deep, and 21 in diameter; the bottom is a grate of cast iron bars (each bar being moveable) to admit the air. Upon the grate is placed a pedestal or stand of cast-iron, of a concave shape, covered an inch thick with coke or charcoal dust, and upon which the pot is placed in which the silver is melted. The pe- destal is nearly two inches thick, and is fully two inches broad- er in diameter than the pot, the object of which is to protect the hip of the pot from the very high heat which the current of air, ascending through the grate, when the furnace is at work, creates, and which would otherwise melt the pot. This precau- tion is essentially necessary, from the pedestal raising the pot so considerably above the grate, and from its being entirely 'surrounded by the fire in the furnace. If the furnace, however, is properly, managed, there is no risk of melting the pot. On the top or mouth of the pot is placed a muffle, which is a ring of cast iron six inches deep, made to fit neatly into the mouth of the pot; the use of this muffle is similar to that used in melt- ing, gold to give a greater depth of fuel in the furnace than the mere length of the pot, and which gives a greater degree of per- fection to the process. The muſlle is also extremely conveni- ent, by giving a depth to the pot, if we may so speak, which enables ingots of silver to be charged, which are longer than the depth of the interior of the pot. . The top of the ring or muffle is covered with a plate of cast iron, to prevent the fuel from falling into the pot, and secure the metal from the action of the atmospheric air when in fusion. Each furnace has a flue inine inches wide and six inches deep. The flue is four inches from the top of the furnace, and proceeds in a horizontal direction, and extends to the flue C, which is nine inches square, and is carried up in a sloping direction to the stack or chimney, which is 45 feet high from the grate of the furnace. When the furnace doors, BB, are closed, the current of air which enters at the grate ascends through the body of the fur- nace, and causes the fuel, which is coke, and which surrounds the melting pot, to burn very intensely. The degree of heat wanted, however, is very nicely regulated by a damper, which is fixed in the flue of each furnace, and exactly fitting the square of the flue, so that any portion of draught can be given to the furnace that may be wanted. The damper is a plate of wrought iron, fixed in a frame, and is easily moved in and out, so as to increase or diminish the size of the flue. It is fixed in the brick-work of the sloping flue C, about 18 inches above the top of the furnace. The furnace doors B have small holes in them to look into the furnace: these are closed by stoppers or plugs of cast iron. When the furnace is put to work, it is łighted by some ignited charcoal being put upon the grate and around the pot (for the pot is always in its place before the fire is lighted); upon the charcoal about three inches deep of coke is put ; the door B is shut, and the damper is pulled out about two inches. When the coke is ignited, a similar quantity is put on, and so continued until the furnace is filled with ignited draws the parts together until they fit. fixed an arched rack L, forming a continuation of the coke. The object of this precaution is to prevent the cracking of the cast iron pot by being too suddenly heated; and it is generally about two hours before the pot can be brought to a charging heat, to do it with perfect safety. Before the silver is charged, the pot is heated a bright red; it is then examined to see if it has cracked in bringing up, as it is technically called. This is done by placing a cold iron tool of considerable thick- ness in the centre of the pot, which immediately renders any crack visible to the eye. When satisfied that the pot is sound, the silver is charged into the pot. With the silver is put into the pot a small quantity of coarsely grained charcoal powder, which coats the inner surface of the pot, and prevents the sil- yer from adhering to it. When the silver is brought to the fusing point, the quantity of charcoal is increased, until it is nearly half an inch deep on the surface of the silver, and which keeps the silver as much as possible from the action of the com- mon air, and prevents that destruction of the alloy which would otherwise cause a considerable refinement in the metal. When the silver is completely and properly melted, it is well stirred with an iron stirrer, so as to make the whole mass of one uni- form standard quality. The pot is then taken out of the fur- nace by the crane, and conveyed to the pouring machine, by which its contents are poured into the ingot moulds. Fig. 2, is the crane, it is supported by a strong column of cast-iron, X, which is firmly fixed in masonry beneath the floor. The gibbet of the crane marked WY, is cast in one piece; it has a collar at e, which fits upon a pivot formed at the upper end of the column X. At the lower part of the gib is a collar which embraces the column near its base. On these two sup- ports the gib turns freely round, so that its extremity W may be placed over either of the furnaces B. B. The wheel work of the crane is supported in two frames z z, which are fixed to the gib by three bolts; it consists of a cog wheel c upon the end of the barrel, on which the chain winds; and a pinion b, which gives motion to the cog wheel. The axis of the pinion has a winch or handle, a, at each end, to turn it round. The chain d, from the barrel, is carried up over the pulley at c, which is fit- ted in a part of the gib immediately over the pivot at the top of the column X. The chain then passes over the pulley W, at the end of the gib, and has the tongs W T suspended to it. These are adapted to take up the pot between the hooks or claws T, at the lower ends. The two limbs are united by a joint like shears, and the upper ends V are connected with a great chain by a few links. The pot has a projecting rim round the edge, and the tongs take this rim to lift the pot out of the furnace. The pot being wound round to the required height by turning the handle a, the gib of the crane is swung round, to bring the pot over the pouring machine, and it is lowered down into it, for the convenience of swinging the crane round a worm which is fixed upon the column X at O, and a worm or endless screw is mounted in the frame 2, to work in the teeth of the wheel. The screw, being turned by a winch on the end of its spindle, will cause the gib to move round on the column. - - Fig. 3 of the engraving represents that part of the pouring machine in which the pot is placed ; m is an axis, which is mounted in the frame of fig. I, by the pivots at its ends. To this axis is fixed a cradle, which receives the pot. The cradle is joined together so as to open and shut, and the screw m To the pot n there is principal bars of the cradle. When the cradle is in its place, as in fig. 1, the rack L is engaged by a pinion K, and can thereby be elevated to pour out the metal at a lip or spout, which is made at the edge of the pot for the purpose. The axis of the pinion K is turned by means of the winch D, with a train of wheels, D, E, F, G ; I, H.; and K. The man who turns this winch stands before the pot, so as to see what he is doing. The frame of the pouring machine is sufficiently evident from the figure. It is so made as to leave an open space beneath for the carriage, fig. 5, containing the ingot moulds. Fig. 4, is a separate view of a pair of ingot moulds, the two parts, R and S, put together and form a complete nuould, as shewn in fig. 5. The upper edge of the mouth is a little enlarged, to facilitate the pouring of the metal. The moulds are made of cast-iron. The part R has the bottom f # ~, i i. 㺠º -— . . Published by Fisher. Son & Cº Caxton. London. Jan. 29, 1827. - .* . . . . M I N M I N DICTIONARY OF MECHANIGAL SCIENCE. 6.79 and one side formed on it, and the other half, S, has one side formed on it. Before the moulds are used, they are heated in an iron closet, which has flues surrounding it, and they are then rubbed on the inside with linseed oil. P,Q, fig. 1, is the carriage into which a row of these moulds is placed, as shewn at 4, and they are screwed up close by two screws p p, so as to hold them tight; the moulds rest upon a plate which is suspended by screws q, at each end, and can by that means be raised or lowered to suit different heights of moulds. The carriage is supported on four wheels Q Q, which run upon a railway. PP is a rack fixed to the bot- tom plate of the carriage ; in this rack, a cog-wheel N acts; the Gog-wheel is turned by a pinion, which has a handle or winch O, fixed upon it; by turning the handle, the carriage is moved along the railway: and any one of the moulds, fig. 4 or 5, can be brought under the spout of the pot, fig. 3; then by turning the handle D, fig. 1, the pot can be inclined so as to pour the metal into the mould until it is full. In the silver melting-house there are eight melting furnaces, two cranes, and two pouring machines. Each crane stands in the centre of four furnaces, freely commanding the centre of cach, and conveys the pots to the pouring machine. The eight furnaces are worked three times daily, and each pot contains, upon an average, 420 lbs. troy, making the total melting 10,080 lbs. There are four men to each four furnaces; each party pour their own pots, and the whole meltings are finished, from the time of first charging in the morning, in little more than ten hours. The whole of the silver meltings are conducted 'under the superintendence of the surveyor of the meltings; and he allows no silver to be delivered to the company of money- ers by the melter, unless he has a written order from the king’s assay master, authorizing such delivery. The meltings are performed by contract with the master of the mint, and his first clerk, as melter. He is responsible to the master for all the bullion he receives, and delivers weight for weight, which renders his situation one of considerable risk and great responsibility. due performance of the duties of his office. The bars of silver, of the approved standard, are delivered over to the moneyers, who perform the various processes of the coinage under con- tract with the master of the mint, always delivering weight for weight. They also give security for the due performance of the duties of their office. . Laminating Rollers employed at the Royal Mint.—The first process to which the silver bars issued from the silver melting department of the royal mint, is subjected, is that of flatting, rolling, or laminating in the rolling mill. The bars, before they are put through the rollers, are heated to redness, which makes them much easier rolled. They are heated in a reverberatory furnace. When the gold bars are subjected to the same pro- Cess they are rolled cold, and a bar of an inch thick can be reduced to the thickness of a half-sovereign, without ever being annealed, and could be reduced much thinner if necessary, and not shew the least symptom of cracking, The drawing (see the plate, fig. 6,) is an elevation of one pair of rollers, and the wheel-work for giving motion to them. A is the upper and B the lower roller; C C are the standards of the cast-iron frame which supports them. Each of these standards has an opening in it to receive the bearing brasses for the pivots of the rollers. The upper roller is suspended in brasses, which are regulated by the large screws F, F, which admit of placing the rollers at a greater or less distance asunder. . This is shewn by the separate figure of one of the screws; h h are the brasses, and k the hole to receive the pivot of the roller. On the upper part of the screw a collarf is fitted; and from this two bolts g g descend, and are fastened to the brasses h h, with nuts beneath. By these the roller is Suspended, but by turning the screw round, the brasses rise or fall; the brasses h h are fitted very accurately into the grooves or openings into the standard CC. For the convenience of turning both screws round together, each has a cog-wheel F fixed on the upper end of it. These are turned by two worms HH, fig. 7, fixed on a common axis, which has a handle G in front: by furning this handle the upper roller is either raised or lower- £d, as is required, but wilf always be parallel to the lower one. The two standards C C are firmly bolted down to the ground. He also finds security for the sills D D, which are of cast-iron, and are bedded in the masonry EE. The standards are further united by bolts a. At the Upper part is a cross bar, fixed between the standards, to support a small table or platform, on which the metal is placed when it is to be presented to the rollers. The rollers are put in motion by a steam-engine. The crank of the engine has a cog-wheel upon it, which turns a pinion. Upon the axis of this is a very heavy fly-wheel, which turns with great velocity. On the end of the same axis is a pinion which turns a large wheel M, and this gives motion to a large shaft N N, which extends beneath the rollers, and is continued a sufficient dis- tance in the same direction, to turn two pairs of rollers, one of which only is represented in the drawing. At L a wheel is fixed on this shaft, to turn the upper roller A, by means of a wheel K, which is supported in the standards k h, and its axis is connected with a short shaft r Ir, with the square on the end of the roller A ; , r are the sockets by which the shafts are joined, and they admit of a little yielding when the roller is raised. The wheel O is fixed on the shaft N, to turn the lower roller B, by means of the wheel P.; but the wheels P and O do not touch, being of smaller diameters, and an intermediate wheel is also applied on one side, so that its teeth engage with both the wheels O and P; by this means, the two rollers A and B are made to turn round in opposite directions, and then their adjacent surfaces will move together. The wheel P is Supported in standards p p, and its axis R connected by a shaft Q, with the lower roller B. There is also a gauge to ascertain the thickness of the plates which are reduced by the operation of the rollers; it consists of two steel rulers fixed fast together at one end, and the other end is a certain distance asunder, forming an opening between them, which gradually diminishes to nothing : the sides of the rulers are divided. In using this gauge to determine the thickness of a piece of plate, the edge of the plate is applied to the opening between the rollers, and the divisions of the rollers shew the distance it will go into the opening before it fits tight; and the thickness is ascertained by the number of the divisions. We now proceed to describe the machine by which the plates of metal from the rolling mill are cut into slips of a con- venient width, for cutting out the circular pieces or blanks which are to form the coin. This width is generally that of two crowns, two half-crowns, and shillings. , Figs. 8 and 9, in the plate, are representations of the cutting machine. L L is a strong iron frame, which is screwed down to the ground-sills of the mill, so that the cog-wheel D will be immediately over the shaft which turns the rolling-mill, and can be turned by a cog-wheel upon that shaft. The cog- wheel D is fixed upon an horizontal axis B B, which is sup- ported in the frame L.L. A.A is a similar axis placed at the top of the frame, and turned round by a cog-wheel C, which engages with the wheel D. On the extreme end of each axis A and B, a wheel or circular cutter E and F, is fixed. The edges of these cutters lie in close contact laterally, and over- lap each other a little. The edges of the cutters are made of steel hardened, and they are turned very truly circular, and the edges which overlap are made very true and square. Whilst they are turning round, if the edge of any piece of metal be presented to them, it will be cut or divided just in the same manner as by a pair of shears. H is a narrow shelf, upon which the plate is supported when it is pushed forwards to be cut, and G is a guide fixed upon the shelf; the edge of the plate of metal is applied against this guide, whilst it is moved forward to the cutters. The guide is moveable, and the distance which it stands back from the cutting edges, or line of contact of the two cutters E F, determines the breadth of the slip of metal which will be cut off. Fig. 9 is another view of fig. 8. To give these slips of metal the exact thickness which is requisite before they are cut up into blocks, they are sub- jected to a more delicate rolling; or they are drawn between dies by a machine, invented by Mr. Barton, the present comp- troller of the mint. Figure 10 represents the finishing rollers, viewed at the end of the frame, in order to shew the manner of adjusting them ; for it is only in those parts that they differ from the great rollers; a is one of the pivots or centres of the upper roller; and is accurately fitted in a collar of brasses, which collar 680 M I N M I N DroTIONARY or MECHANICAL scIENCE.” is held down in a cell at the top of the standard by a cap d, with two bolts and nuts. These are not intended for the adjustment of the rollers, as in the former instance, but the lower roller is moved for this purpose. The pivot b of the lower roller is received in a brass bearing, which is moveable in the opening in the standard frame. The brass rests upon a wedge c, which is fitted in a cross mortise through the standard. By forcing the brass farther in the wedge of the lower roller, it will be moved nearer to the upper roller. The standard at the other end of the rollers is made in the same manner, and the wedges of both must be moved at the same time. To give them motion, a screw f is ſitted into each wedge, and upon these screws are worm wheels g, which are both moved by worms cut upon an horizontal axis, that extends across from one end of the frame to the other, and has a handle at the end to turn it round by, and move the screws and wedges both in equal quantity; l is the table on which the metal is laid to present it to the rollers. The following engravings are descriptive of a new machine, invented by Mr. Barton, and employed at the royal mint for drawing the slips of metal between dies, by which a greater degree of accuracy and uniformity is obtained in the thickness 'of the metal. The operation is similar to wire-drawing. The 11th, 12th, and 13th figures, represent a small machine for thinning the ends of the slips of metal, so that they will enter into the dies through which the whole of the slip is to be drawn. It is a small pair of rollers, which are shewn on a large scale in fig. 11. A is the upper roller, and B the lower; this has three flat sides, as represented; C is the slip of metal. put between the rollers; D is a stop, adjustable in the line of the motion of the slip of metal C. The twelfth figure is an end view, and the 13th a side view, of the frame or machine in which the rollers are mounted. A, B are the rollers, which are made to turn together by pinions a, b. F is a large cog- wheel, which is fixed on the end of the axis of the lower roller. This cog-wheel is turned by a pinion G, which is fixed on an axis extending across the machine, and having a fly-wheel fixed on one end, and at the other a drum H, to receive an endless strap, by which the machine is put in motion ; a crank is formed on the middle of this axis, and a rod d, is joined to the crank, to connect it with the moving blade K of a pair of shears, of which the other blade L is fixed to the frame. The distance of the rollers is regulated by a screw e e, at the top of each standard. These screws have pinions at the top of them, and are turned round by a pinion, which is placed between them, and engages the teeth of both pinions, so as to give motion to the two screws at the same time, when the middle wheel is turned round by a cross handle, which is fixed to the top of it. If the slips of metal which are to be put into this machine are not exactly square at the ends, they are cut off smooth and square by the shears, which keep constantly mov- ing ; the end of the slip is then presented between the rollers, not on that side which would draw them in between the rollers, as in common rolling, but on the opposite side ; when one of the flat sides of the lower roller comes opposite the upper roller, then the piece of metal can be pushed forwards between the two, until the end stops against the stop D, as in fig. 11; then as the rollers turn round, and the flat side of the lower roller passes by, the cylindrical parts of the roller will take the metal between, and roll it thinner at the end which is between the stops and the point of contact of the rollers. Figs. 14 and 15. Fig. 14 is a section, to shew how the slip of metal C is drawn between the dies by the tongs, of which fig. 15 is a sort of ground plan. The dies are two steel cylinders made very hard, and extremely true; fitted into two sliders D, D, and held fast by clamp pieces screwed against them. The cylinders are accurately fitted into their beds in the slides, so that the steel shall be firmly supported, and prevented from bending or turning round, and to present but a small portion of their cir- cumference against the slip of metal. The sliders D, D are fitted into a box, figs. 14 and 16; they fit flat on the bottom of the box, and two clamps F, F are screwed against-the sliders, to confine them to the box. The lower slider is supported by two screws, f, f, and the upper side is forced down by a large screw G.; this has a cog-wheel fixed on the top of it, with a pinion and lever to turn the screws round very slowly, and regulate the distance between the dies. H is a clamping nut; fitted upon the screw, to take off all possibility of shake ; the sliders also are bound fast sideways by screws tapped through the sides of the box, the points of which press upon steel plates between them and the sliders. In order to render the contact between the points of the screws supporting the under side, and the point of the adjusting screw, forcing the upper slider, still more complete, two extending screws are intro- duced at the ends of the steel dies between the sliders, by which a sufficient degree of contact to overcome the spring of the materials may be excited, before the dies come into action on the slip of the metal, fig. 15. Rolling Machine. The box of dies, fig. 17, is fixed at one end of a long frame. This frame supports two axes A A, one at each end. .." these axes wheels are fixed, to receive end- less chains B B, which move along a sort of trough or railway; formed on the top of the frame. The chains are kept in motion by a cog-wheel C, which is fixed upon the axis most remote from the box of dies. This cog-wheel is turned by a pinion D, on the axis of which is a wheel E; and this wheel is turned by a pinion F on the axis of the drum G, which is moved by an endless band, proceeding from some of the wheels in the mill, and which is thrown in and out of geer at pleasure by a tighten- ing roller. The slip of metal is drawn through the dies by the chain, with a pair of tongs. - . Figs, 14 and 15—a b are the two jaws of the tongs, which are united with each other by the joint pin c. This has fitted on each, a small roller or wheel, which runs upon the railway or top of the frame; d d, fig. 15, are a similar pair of wheels, the axle of which is connected with two links e e ; this axle passes between the tails of the tongs, but is not fixed to them. The ends of the links have a double hook formed on them, as shewn at fig. 15. The tongs run upon their wheels immediately over the endless chain, so that when the end of the links ee is pressed down, one of the books catches on a cross pin of the chain, as in fig. 15; the axle of the wheel d d acting between the inclined parts of the tails of the tongs, tends to throw them asunder, and, at the same time, the jaws of the tongs bite with very great force; the links e e draw the tongs along with the chain BB. The links are carried a long way beyond the axle of the wheels, and have a sufficient weight h fastened to them, which will lift up the hooked end f, and disengage it from the chain, except when there is a considerable strain on the tongs. . To use this machine, a boy takes hold of the tongs by the handle r, when they are disengaged from the chain, and pushes the tongs forward to the box of dies. The tongs run freely upon their wheels, and the jaws open when moved in that direction, because two small pins i i, are fixed between the links, and acting on the outsides of the tails of the tongs, close them together, and this at the same time opens the jaws. The tongs are pushed up close to the box of dies, and the jaws enter into a recess N, fig. 14, which is formed for that purpose. Another boy takes a slip of metal, which is previously made thin by the rollers, fig. 11, and introduces it between the dies, and also between the jaws of the tongs, which are open. The boy who holds the tongs now takes the handle s, which is fixed on the back of the tongs, and holds it fast, whilst with the other hand he draws the handle r, at the end of the links, away from the tongs. This has the effect of closing the jaws of the tongs upon the slip of metal between them; at the same time the boy depresses the handle 7", and the hook at the end of the links e e will be caught by the first cross-pin of the chain which comes beneath them. This puts the tongs in motion; but the first action is to close the jaws, and bite the piece of metal with great force, in consequence of the axletree of the wheels being placed between the inclined planes of the tongs. When the tongs have closed on the metal with all their force, they move with the chain, and draw the slips of metal through the dies, which, operating upon the thicker part of the slip with greater effect than upon the thin, reduces the whole to an equable thickness. When the whole is drawn through, the strain upon the tongs is gradually released; and the weight lifting up the hook at the other end of the links, they are ready to be advanced again to the die, to draw another bar. The frame, of which we have given a drawing, contains two pair of dies, and the same wheel serves for both. At the mint there are two - Z2%-> * zz/f/2. * ~ O %22.2% AZZZz. 68/. EC . . s WAWAVWWWW P Aïø. 20 . - - - © S} G Ø º H 4–4–A +== © EH L - 42xazz, sz Published by Fisher. San F. CŞ. Caxton . .ondon. Feb. 3-1 lº’. M 1 N. M 1 N DICTIONARY OF MECHANICAL scIENCE. 681 machines of this description; they are placed side by side, with a sufficient space for the boys to work between them. These machines were made by Mr. Maudsley, under the direc- tion of the inventor. The slips of metal produced from this machine are considerably more uniform in thickness than when finished at the adjusting rollers; consequently, the individual pieces are made more nearly to the standard weight, which was the object in view by this invention. This has become a point of great importance in the practice of the mint, from the remedy on gold in weight being reduced from 40 to 12 troy grains. When the pieces cut from slips of metal, prepared from the drawing machine, are pounded and weighed, which is telling the number of pieces in a pound troy, sovereigns; or half sovereigns, the variations from standard either way seldom exceed three grains troy. It is reckoned good work from the adjusting rollers when the variations are under six troy grains. Adjusting. The blanks, after being cut out by Bolton's cutting-out press, are carried to the sizing room, where each individual piece is adjusted to its standard weight. The light pieces are selected for remelting, and the heavy ones, if not considerably beyond weight, are reduced to their standard weight by rasping their surfaces with a coarse rasp or file. The superior accuracy of Mr. Barton's beautiful machine (described above) has considerably abridged the labour of this inelegant and unmechanical process. The pieces thus adjusted are in a state of great hardness, from compression by the rolling and drawing processes, and by which, in fact, their iatent heat has been squeezed out. They attain their softness again by being heated to a cherry red heat in a reverbatory furnace; after which they are boiled in a very weak sulphuric acid, which makes them very clean, and of a very white colour. When dried, either in warm sawdust, or over a very slow fire, they are in a state for the two next processes, which are the milling, and the coining or stamping. Milling. Plate II. The operation of milling is to be performed round the edge, to prevent their being clipped or filed, which was a fraud commonly practised upon the ancient money made before the introduction of milling or lettering round the edge. The construction of the milling machine will be easily under- stood, from the inspection of figs. 1 and 2, being an elevation and plan of the same. The parts which operate upon the piece of money, consist of two steel bars or rulers D D, the adjacent edges of which are cut or fluted; the lower bar, seen in plan fig. 2, is immoveable, being fastened down by two clamps to a cast-iron plate D, forming the base of the whole machine; the upper bar is prevented from rising by the two vertical pieces, but has the liberty of moving backwards and forwards in the direction of its length, and is guided in such motion by laying half its thickness in a groove formed in the plate D. A rack, C C, fig. 1, is fixed to the moving ruler, which engages in the teeth of the wheel B, mounted on an axis lying across at right angles to the ruler, and supported at its ends by two standards rising up from the plate D. On one end of the axis a handle is fixed for giving motion to the machine. Two blanks are put into the machine at the same time, as seen in the second figure, and the lower ruler can be made to approach nearer to, or recede farther from, the upper ruler, by the two screws ff, to take in a different sized piece between them. The operation of the machine is very simple. Two blanks being placed between the edges of the rulers, the handle A is turned round half a turn, which moves the upper ruler end ways, sufficient to mark the blank all round the edge. The two milled pieces are then taken out, and two other blanks are placed between the rulers; the handle A being turned half round in an opposite direction, carries the upper ruler back again to the position in which it first stood ; thus two more blanks are milled, and so on. The machine is placed upon a strong wooden bench, to raise it to a convenient height for the man who turns the handle ; the blanks are placed in the machine by a boy, near to that where the handle is. - - The 3d and 4th figures on Plate II. are further illustrations of Bolton's cutting-out press. Fig. 3 shews the manner of the horizontal wheel acting on the roller F. It represents a hori- zontal plan of the upper part of the axis, S, ſig. 3, is part of the rim of the large wheel, and T, one of the projecting cogs, which, when the wheel turns in the direction of the arrow, will 70. take the roller F, at the end of the lever FD, and turn the lever round in that direction which will wind up the screw, and raise the punch out of the die. This action also draws a rod H, which is connected with the lever by a joint; the other end is connected with a bended lever, from the other end of which a rod descends, and has a piston fixed to it. Fig. 4 is the catch. At K it is moveable on a joint E, and is thrown upward by a spring k. To this spring a cord O is fastened, and the lower end of the cord has a treadle fastened to it. For a perspective view of Barton’s Rolling Machine, see the plate. . . Coining Press.-We now proceed to give a description of the Coining Press, an elevation of which is exhibited in fig. 5, in the Plate. C C C is a strong cast-iron frame, screwed down on a stone basement; the upper part is perforated perpendicu- larly, to receive the screw, D. One of the steel dies which strike the coin, is fixed to the lower end of this screw by a box, fig. 6, and the other die is fixed, in a box, fig. 7, which is fastened down upon the base of the press. The heavy balance weights, R. R, fig. 5, are fixed on the top of the screw, which, being turned round, press the upper die down upon the blank piece of coin, which is laid upon the lower die, and gives the impres- sion; a sufficient force being obtained from the momentum of the loaded arms, R. R. The motion is communicated to the screw by a piece, A, which ascends to the ceiling of the coin- ing-room, and is worked by a steam-engine, with machinery, in the apartment in the room over the coining-room. - Eight presses, similar to this, are placed in a row upon the stone basement, and very strong oak pillars are erected upon the basement, and reach to the ceiling. Each press is con- tained between four such pillars, and iron braces are fixed horizontally from one pillar to another on the opposite side. These braces support blocks of wood, against which the ends, R. R., of the arms strike, to stop them from moving farther than necessary, as, without such precaution, the hard steel dies would sometimes come in contact, and be broken. The piece of blank coin is contained within a steel ring or collar, whilst it is stamped, and this preserves its circular figure. The ring is shewn at a large size at W, fig. 9, V, fig. 8, is a three-pronged spring, which always bears the spring upwards; the opening through the ring, W, is made to fit upon the neck of the lower die, T, fig. 7. When the ring is dropped upon the neck of the die, the upper surface of the ring and of the die will be in one plane. The ring admits of being raised up upon the neck, and will then form a recess or cell, which is just adapted to receive a piece of money. The collar, W, is made to rise and fall upon the neck of the die by means of the levers, G. G., fig. 8; these are fitted upon centre-pins or joints, in a large ring, g g, which is placed on the outside of the box, fig. 7, containing the lower die, T, and is fixed fast upon it, as shewn in fig. 5, by clamp- ing the screws, g g. The levers, G. G., are forked at the outer ends, to admit studs at the lower ends of iron rods, B E, which rise up through holes in the solid metal of the press, and are united to a collar, G, fitted on the upper part of the screw, D. When the screw of the press is turned back, and the upper die is raised up, the rods raise the outside ends of the short levers, G, and the inside depresses the ring; a blank piece of money is laid upon the die, and when the screw is turned to bring the upper die down upon it, ready to stamp the impression, the levers, G, are released, and the triple spring, V, lifts: the collar up, so that it surrounds the piece of money ; and in this state the blow is struck. Immediately after, the press returns by its recoil, and then the levers, G, force the collar down upon the neck of the die, and leave the piece free. The lower die is fixed in a box, fig. 7, by the screws, t t, which admit of adjust- ing it with precision beneath the upper die. The box, fig. 7, is screwed down upon the base of the press by four screws. The upper die is shewn at S, fig. 6, which explains how it is fastened to the screw; v v are four screws, by which the die is held in a box, fig. 6. The box is fitted into a ring or collar, as shewn by the dotted lines, F; see also fig. 5. The arms of the collar, F, are attached to the rods, E E, by two nuts at each end; and this makes the collar, F, and the box, fig, 11, always follow the screw, and keep in close contact with the end of the screw, which enters into a cell on the top of the box, fig. 6, but leaves the screw at liberty to turn round independently of the box. Fig. 2, is a ring, which is fastened by its screws, w w, to the 8 L 682 M I N M. I. Nº Drction ARY of MECHANICAL scIENCE, screw of the press; a claw, Y, descends from the ring, and enters into the cavity, o, in the edge of the box, fig, 6, which cavity is nearly three times as wide as the claw, Y, and there- fore allows the screw to turn round for a certain distance with- out turning the box, fig. 6; but beyond the limits of this motion the screw and the die will turn round together. The intention of this is to press, the upper die down upon the coin with a twisting or screwing motion; but if the die was to rise up with a similar motion, it would abrade and destroy the fine impres- sion; for this reason the notch, o, is so wide, as to allow the serew to return, and raise the die from immediate contact with the coin, before it shall begin to turn round with the same motion as the screw. Fig. 11, is a box, which is screwed over the box for the upper die, as shewn in fig. 1, in order to keep the upper die firm in its cell. The great screw of the press is made cylindrical at the upper and lower ends, as represented in fig. 5, and their ends are accurately fitted in collars, which are bound tight by screws, the real screw or worm is partly concealed within the solid metal frame, and has no other office than to force the die down, the guidance laterally being effected by the collars. It now only remains to shew how the Coining Press is made to remove every piece of money which it strikes, and to feed itself with a fresh blank piece. HIK, fig. 5, is a lever, of which I is the fulcrum; it is sup- ported in a bar, Q, fixed vertically from the cheek of the press, and steadied by a brace. The upper end of the lever is actu- ated by a sector, which is fixed upon the screw, D. When the screw turns round, the groove in the sector being of a spiral curve, will move the end, H., of the lever, to and from the screw; and the lower end, K, of the lever being longer, it moves a considerable distance to and from the centre of the press. A socket or groove in a piece of metal is fixed to the perpendicular bar, Q, and the upper end of the lever, H, is guided in this groove to prevent any lateral deviation. The lever K, gives motion to a slider, L, fig. 20, which is sup- ported in a socket, O, screwed against the inside cheek of the press; and the slider 20, is directed exactly to the centre of the press, and on the lever of the upper surface of the die. Figures 14 and 20, represent four views of the slider and socket; NM 0, fig. 14, is a kind of trough or socket in which the slider runs: this slider is formed of two pieces, hollowed out on the sides, which are put together, and the two pieces are held together by screws. O is the part by which the socket is fastened to the press. The slider is a thin steel plate, p, and this is made in two pieces, P and p, which are united by the joint q, fig. 15. The extreme end is made with a circular cavity; and when the two limbs shut together, they will grasp a piece of money between them, and hold it by the edge; but if the limbs are separated, the piece will drop out. The Himb, p, of the slider, is opened or shut ay the same movement which moves the slider end ways in its socket. Thus a plate, L, is applied flat beneath the socket, MN, and has an edge turning up and applying to the upright edge of the socket. A pin is fixed into this edge, and is embraced by the fork at the lower end of the lever, K, fig. 5. By this means the sliding piece, L, is made to move on the outside of the socket, N. It is kept in its place by a fillet, k, fig. 14, which is screwed to the upright edge of L, and the fillet enters a groove formed along the upper surface of the socket, N. - The sliding piece, L, is made to move the steel slider within the socket by means of three studs, which project upwards from the bottom plate of L, fig. 16, at r r, s, and pass through grooves in the bottom plate of the slider, so as to act upon the steel slider, P, in the manner shewn in fig. 15. The left-hand piece, ºr, is received into an opening in the middle of the slider, P, fig. 15. The other two studs, r and s, fig. 16, include the shank of the limb, p, between them, and these studs are cut inclined, so that, when the piece, L, is moved to the right, the studs, r s, will close the limb, p, until they are shut, and then the studs will carry the slider forward ; but, if the sliding piece, L, is moved to the left, its studs will first close the limbs, and will then draw back the slider on the top of the socket, N.; a tube, M, is placed, figs. 15 and 20, and it is filled with blank pieces of coin; the tube is open at bottom to the slider, and the pieces rest upon.it. . When the screw of the press is screwed down . *, ^., thé slider; P, draws back to its farthest extent, and the circle formed at the end between its limbs comes exactly beneath the tube, M ; the limbs being open, a blank piece of coin drops down into the circle of the slider; then the screw of the press, in returning, moves the lever, HI K, and the piece, L; this acts by its studs upon the moveable limb, p, and closes it upon the blank piece; the studs having now found a reaction, push the slider, P, forwards in its socket, and carry the piece for- ward upon the die, as shewn in fig. 13, and which will push off the piece last struck. The screw having now arrived at its highest position, begins to descend, and the slider, L, to re- turn; but the first action of the studs of the sliding piece, L, is to open the limb, p, and then the slider withdraws, leaving the piece of money placed upon the die. As the screw of the press descends, the ring, w, rises up to enclose the piece, as before mentioned, whilst it receives the stroke, and the slider, P, at the same time returns to take another piece from the tube, M, in the same manner as before described. . Fig. 13, is a section, to shew the manner of mounting the lower die for a coining press. This is used in the French Mint. V is a piece of metal or box, as it is placed upon the base of the press, and held down by a ring with screws, l; this holds it fast, but admits of lateral adjustment. In the top of the box is a hemispherical cavity to receive the hemisphere, W.; the upper side is flat, and the die, T, is placed upon it, to hold the die down ; it has a small projecting rim at the lower edge, and a rim, X, is screwed upon the outer edge of the box, V, to hold the die down. The object of this plan is, that the die may always bear fairly to the money which it is to strike. Figures 7 and 18, represent a divided collar, invented by Mr. Droz, for striking money with the letters round the edge. X, fig. 18, is a very strong piece of iron, which has a circular opening through the centre; into this, six segments, w, w, are fitted, and between them they leave an opening, W, the size of the piece of money; the interior edges of these segments are engraved with the pattern or device which it is required to impress upon the edge of the piece. The segments are fitted in the piece, X, by centre pins, upon one of which pins each segment can rise in the manner of a centre. The intention of this is to have a piece of money placed on the die within the space, W.; then, when the pressure is made upon the piece, the die descends some space, and by this mo- tion the segments close together around the edge-piece, and imprint upon the edge of it. When all the segments come into one plane, the die arrives at the firm seat, and the metal re- ceives the stroke which makes the impressions on its surfaces. The die is suspended in a sort of cup, which rises and falls with the screw, nearly the same as the collar, F, in fig. 13. The money, when struck, is passed through tubes of the diameter of the different species, which readily detects any pieces which may have been improperly struck. - - Mr. Bolton's Cutting-out Press employed at the Royal Mint.— In the process of coining followed at the Royal Mint, plates of metal are cut out into circular pieces, nearly of the size of the intended coin, by a machine invented by Mr. Matthew Bolton, and for which he obtained a patent in 1790. A drawing of it is exhibited in fig. 12, where C C C is a cast-iron frame, that is fixed on a stone basement. E is a screw, which is fitted through the top of the frame, and actuates a slider F. At the lower end of the slider a steel punch a is fixed, the diame- ter of which is equal to that of the pieces which are to be cut out : e is the steel die, which has a hole in it of a proper size to fit the steel punch; d is a box, with screws for adjusting the die, so that the hole in it will be exactly beneath the punch. The slider F is fitted into a socket G, which guides it, so that it descends exactly into the hole in the die. e is a piece of iron fixed at a small distance above the die c, and with a hole through it to admit the punch; the design of this picce is to hold down the piece of metal when the punch rises, otherwise the piece would stick to the punch. On the upper end of the screw a piece Q is fixed, from which an arm projects, with a weight P at the end; it is this weight which gives the neces- sary momentum to punch out the piece. D is a spindle fixed upon the piece Q, in the line of the screw, and supported in a collar A at the upper end; above this collar a lever D G F is fixed, at one extremity of which there is a roller F, that is M I R. M. I. R. 683 DICTIONARY OF MECHANICAL SCIENCE. acted upon by the projecting teeth of a large horizontal wheel, turned round by the power of a mill. When the wheel turns winds up the screw, and raises the punch out of the die. The same action draws a rod H, which is connected with the lever | by a joint: the other end of this rod is connected with a bended lever, from the other arm of which a rod descends, and has a piston fixed to it. This piston is fitted into a close cylin- der; hence, when the piston is drawn up, it makes a vacuum in the cylindor, and the pressure of the atmosphere on the pis- ton causes a reaction ; and the instant that the roller F escapes ur slips off from the tooth of the wheel, the reaction of the pis- ton draws the joint H back, and makes the screw turn round in that direction, which causes the punch to descend and cut out a piece from a plate of silver or gold laid upon the die. When the machine requires to be stopped, there is a catch, which is suffered to rise up and hook the lever G. The catch is thrown up by a spring, to which a cord, with a treadle, is fastened. A boy who applies the plates of metal to this machine, places his foot on the treadle, draws down the spring and catch, and then the machine makes a cut every time that a cog of the great wheel passes by; but if the boy relieves the treadle, then the spring lifts up the catch; and when the end of the lever G comes over the catch, it will be caught thereby, and held fast from re- turning by the action of the exhausted cylinder. R is a strong wooden spring, against which the balance-weight P strikes to stop its motion when it has made its required stroke to pierce the plate. Twelve of these cutting-out presses are to be seen at the Royal Mint, arranged in a circle round a great wheel, which is turned by a steam-engine, and has a large fly-wheel fixed on the same axis, just above the wheel, to regulate the motion. The stone basement on which the presses are fixed is circular, and the bearings A are all fixed in a circular iron frame, erected on an iron column placed between each press. The whole forms a very handsome colonnade, and is placed in the centre of a circular room, which is lighted by a sky-light in the dome. The air cylinders are placed within hollow pilasters, which ornament the walls of the room, and appear to support the dome. The whole presents as elegant an arrangement of machinery as can well be conceived. MINT. See MeNTHA. - . . MINUTE, the sixtieth part of a degree; or, in time, the six- tieth part of an hour. These are both denoted by a small dash, as 'placed over the number of them ; though, to prevent con- fusion, it is better to mark the latter by a small m. MIRA, a singular star in the neck of Cetus, discovered in 1596, and marked in the British catalogue as a star of the third | magnitude, appears and disappears periodically seven times in six years, continuing in the greatest lustre for fifteen days together. During 334 days, it continually shines with its great- est light, appearing as a star of the third magnitude; then it diminishes till it entirely disappears for some time from the naked eye. In fact, during that period it passes through its several degrees of magnitude, both increasing and diminishing. MIRACLE, in its original sense, is a word of the same im- port with wonder; but in its usual and more appropriate signi- fication, it denotes “an effect contrary to the established con- stitution and course of things, or a sensible deviation from the known laws of nature.” The history of almost every religion abounds with relations of prodigies and wonders, and of the intercourse of men with the gods; but we know of no religious system, those of the Jews and Christians excepted, which appealed to miracles as the sole evidence of its truth and divinity. The pretended miracles mentioned by pagan histo- rians and poets are not said to have been publicly wrought, to enforce the truth of a new religion, contrary to the reigning idolatry. Many of them may be clearly shewn to have been merely natural events. See MAGIC. Others of them are represented as having been performed in secret on the most trivial occasions, and in obscure and fabulous ages, long prior to the era of the writers by whom they are recorded. And such of them as at first view appear to be best attested, are evidently tricks contrived for interested purposes; to flatter power, or to promote the prevailing superstitions. For these reasons, as well as on account of the immoral character of the divinities by whom they are said to have been wrought, they are altogether unworthy of examination, and carry in the very nature - of them the completest proofs of falsehood and imposture. it catches the roller F, which turns the lever round, and thereby | MIRAGE, a name given by the French sailors to an optical phenomenon, on which M. Monge read his memoir to the Institute at Cairo, during the French invasion of Egypt. It often happens at sea, that a ship seen at a distance appears as if painted in the sky, and not to be supported by water. A similar effect was observed by the French in the course of their march through the Desert. seemed to be built on an island in the middle of a lake. The villages seen at a distance, In proportion as they approached, the apparent surface of the water became narrower, and ultimately disappeared entirely; while the same illusion was repeated on a village at a little farther distance. This phenomenon has been variously ac- counted for by different philosophers. Monge ascribes the effects to a diminution of density in the lower stratum of the atmosphere. This, in the Desert, is produced by the increase of heat, arising from those communicated by the rays of the sun to the sand with which this stratum is in immediate con- tact. At sea, it takes place where, by particular circum- stances, such as the action of the wind, the lower stratum of the atmosphere holds in solution a greater quantity of water than the other strata. In this state of things, the rays of light which come from the lower part of the heavens, having arrived at the surface that separates the less dense stratum from those above it, do not pass through that stratum, but are reflected, and paint in the eye of the observer an image of the heavens; which appearing to him to be below the horizon, he takes it for water when the phenomenon occurs on land. And if at sea, he thinks he sees in the heavens all those objects which float on that part of the surface occupied by the image of the heavens. MIRROR, in Catoptrics, any polished body impervious to the rays of light, and which reflects them equally. Mirrors ... were anciently made of metal; but, at present, they are gene- rally smooth plates of glass, tinned or quicksilvered on the back part, and called looking-glasses. plane, convex, or concave. light in the direction exactly similar to that in which they fall upon it, and therefore represents bodies of their natural mag- nitude. more than before reflection, and therefore greatly diminish the images of those objects which they exhibit: while the concave †Mirrors are either The first sort reflects the rays of But the convex ones make the rays diverging much ones, by collecting the rays into a focus, not only magnify the objects they shew, but will also burn very fiercely when exposed to the rays of the sun: and hence they are commonly known by the name of burning mirrors. Some of the more remarkable laws and phenomena of plane mirrors are as follows:–1. A spectator will see his image of the same size, and erect, but reversed as to right and left, and as far beyond the speculum as he is before it. As he moves to or from the speculum, his image will, at the same time, move towards or from the specu- lum, also on the other side. In like manner, if, while the spec- tator is at rest, an object be in motion, its image behind the speculum will be seen to move at the same rate. Also when the spectator moves, the images of objects that are at rest will appear to approach or recede from him, after the same man- ner as when he moves towards real objects. 2. If several mir- rors, or several fragments or pieces of mirrors, be all disposed in the same plane, they will only exhibit an object once. 3. If two plane mirrors, or speculums, meet in any angle, the eye, placed within that angle, will see the image of an object placed within the same, as often repeated as there may be perpen- diculars drawn determining the places of the images, and ter- minated without the angles. See OPTICS . MISCHIEF, in Law. Malicious mischief is an injury of such a gross nature to personal property, that although it is not done with a felonious intention, or an intent to steal, the law has inflicted punishment upon it by various statutes. Of these, are statutes against destroying dikes and bridges in the fens of Norfolk, &c.; setting fire to stacks of corn, &c., and imprisoning persons on the borders for the purpose of obtain- ing ransom; killing cattle, maiming sheep, &c., a trespass punishable with treble damages. Captains and mariners set- ting fire to ships is felony, and also making a hole in a ship in distress, &c., is felony, and death by statute 12 Anne, S. 12, 684 M I S. IM I Z. DICTIONARY of MECHANICAL SCIENCE. c. 18. Wilfully and maliciously tearing, cutting, spoiling, or || defacing the garments of any person in the streets or highways, or assaulting, with intent to do so, is felony. There are acts which relate to the prevention of setting fire to out-houses with corn, damaging fishponds, trees, planted in gardens, cutting down sea-banks, hop-binds, setting fire to mines, preventing persons from-buying corn, setting fire to gorse, furze, &c.; wil- fully burning engines in mines, fences, enclosures, breaking into houses of the plate glass company, with intent to destroy utensils; breaking into houses to cut or destroy cloth, serge, linem, &c., in the loom, and other similar offences. MISCHNA, or MISNA, the code or collection of the civil law of the Jews. The Jews pretend, that when God gave the writ- ten law to Moses, he gave him also another not written, which was preserved by tradition among the doctors of the synagogue, till rabbi Juda, surnamed the Holy, seeing the danger they were in, through their dispersion, or departing from the tradition of their fathers, reduced them to writing. The Misna is divided into six parts: the first relates to the distinction, of seeds in a field, to trees, fruits, tithes, &c. . The second regulates the man- ner of observing festivals; the third treats of women and matri- monial cases; the fourth of losses in trade, &c.; the fifth is on oblations, sacrifices, &c.; and the sixth treats of the several sorts of purification. - - - - MISDEMEANOUR, in Law, signifies a crime: Every crime is a misdemeanour; yet the law has made a distinction between crimes of a higher and a lower nature; the latter being denominated misdemeanours, and the former felonies, &c. For the understanding which distinction, we shall give the following definition from Blackstone's Commentaries, vol. iv. p. 5. “A crime, or misdemeanour, is an act committed or omitted, in violation of a public law, either forbidding or com- manding it. This general definition comprehends both crimes and misdemeanours; which, properly speaking, are mere synonymous terms; though, in common usage, the word crime is made to denote such offences as are of a deeper and more atrocious dye; while smaller faults and omissions of less con- sequence, are comprised under the gentler name of misde- meanours only.” . . . . - MISE, in Law books, is used in various senses. Thus it sometimes signifies costs or expenses, in which sense it is commonly used in entering of judgments in actions personal. It is also used for the issue to be tried on the grand assize; in which case, joining of the issue upon the mere right, is putting in issue between the tenant and demandant, who has the best or clearest right. . - ... • * MISERICORDIA, in Law, is an arbitrary fine imposed on any person for an offence. This is called misericordia, be- cause the amercement ought to be but small, and less than that required by magna charta. If a person be outrageously amerced in a court that is not of record, the writ called moderata misericordia, lies for moderating the amercement according to the nature of the fault. MISFEASANCE, in Law books, signifies a trespass. MISFORTUNE, an unlucky accident.— Misfortune, or chance, in Law, a deficiency of the will; or committing an unlawful act by misfortune or chance, and not by design. In such ease, the will observes a total neutrality, and does not co-operate with the deed ; which therefore wants one main ingredient of a crime. See CRIME. Of this, when it affects the life of another, we have spoken under the article HomicIDe; and in this place have only occasion to observe, that if any ac- cidental mischief happen to follow from the performance of a lawful act, the party stands excused from all guilt; but if a man be doing any thing unlawful, and a consequence ensues which he did not foresee or intend, as the death of a man, or the like, his want of foresight shall be no excuse; for, being guilty of one offence, in doing antecedently what is in itself unlawful, he is criminally guilty of whatever consequence may follow the first misbehaviour. MISNOMER, in Law, a misnaming or mistaking a person's name. The Christian name of a person should always be per- foct; but the law is not so strict in regard to surnames, a small mistake in which will be dispensed with, to make good a contract, and support the act of the party. See Plea to INDICTMENT. . - t - the moneyers. and divided into twenty-four doits. MISPRISION, a neglect, oversight, or contempt, applied chiefly to misprision of treason, which is a negligence in not revealing treason, or felony, to a magistrate, where a person knows it to be committed : it is also applied to great misde- meanours. It is, therefore, negative or positive, as it is an act' ' or a concealment of crime. To avoid misprision of treason, the party must make full discovery to a magistrate. To counter- feit foreign coin, not current here, is misprision of treason. A misprision of felony may be by concealing it, or by taking back again a man's goods which have been stolen, which is now made felony. Concealing treasure trove falls under this head. In the class of positive misprisions, or high misdemeanours, are the mal-administration of high officers, and embezzling public money. Contempts against the king's authority, some of which incur a praemunire; contempts against the king's palace or courts. In the palace, if blood be drawn in a mali- cious assault, it is punishable by perpetual imprisonment, fine, and loss of the offender's right hand, 33 Henry VIII. c. 12. And striking, whether blood is drawn or not, in the king's superior courts, or at the assizes, is punishable with equal or greater severity. A rescue of a prisoner in such a court is punished with perpetual imprisonment, and forfeiture of goods, and the profit of lands during life. Of a less degree are reckoned also the injurious treatment of those who are under the immediate protection of a court of justice, the dissuading a witness from giving evidence, and the disclosing, by a grand jury, to the person indicted, of the evidence against him. - MISRECTTAL, in deeds, is sometimes injurious, and some- times not; if a thing be referred to time, place, and number, and that is mistaken, all is void. MISSIONARIES, such ecclesiastics as are sent by any Christian church into pagan or infidel countries, to convert the natives, and establish the Christian religion among them. Custom, the tyrant of language, has applied this term in a sense very different from its original acceptation; for there may be missions political or commercial, as well as religious. MISSIVE, something sent to another, as missive letters; meaning letters sent from one to another upon business, in contradistinction to letters of gallantry, points of learning, despatches, &c. + . - - - MITE, a small coin, formerly current, equal to about one- third of a farthing. It also denotes a small weight used by It is equal to the twentieth part of a grain, MITRE, a sacerdotal ornament worn on the head by bishops, and certain abbots, on solemn occasions; being a sort of cap, pointed, and cleft at top. The high priest among the Jews wore a mitre or bonnet on his head. The inferior priests among the Jews had likewise their mitres. Those young women among the primitive Christians who professed a state of virginity, and were solemnly consecrated thereto, wore a purple and golden mitre as a badge of distinction. The pope has no less than four different mitres, which are more or less rich, according to the solemnities of the festivals on which they are worn. - The cardinals anciently wore mitres ; some canons of cathedrals have the privilege of wearing the mitre ; and some great families in Germany bear it for their crest. MITTIMUS, a writ by which records are transferred from one court to another. The precept directed to a gaolor, under the hand and seal of a justice of the peace, for the receiving and safe keeping a felon, or other offender, by him committed to gaol, is called a mittimus. * - MIZZEN, the aftermost or hindermost of the fixed sails of a ship, extended sometimes by a gaff, and sometimes by a yard which crosses the mast obliquely, the fore end reaching almost down to the deck, and the after end being peeked up as high above the middle of the yard which is attached to the mast; the head and foreleech, or the mizzen, are laced upon the gaff (or yard) and mast, and the sheet hauls out near the taſſerel, Mizzen Mast, the mast which supports all the after sails. The explanations of the rigging, yards, and sails of this mast being in general applicable also to the same furniture of both the other masts, the reader is referred to the articles SHROUD, STAY, YARD, &c. observing only that the epithet of Fore, Main; or Mizzen, is added to each term, to distinguish them from each other. ~ : * * - .AM N E M & # DICTIONARY OF MECHANICAL SCIENCE. 685 . MNEMONICS, the art of improving the memory. It suffi- ciently appears that the principal expedient for assisting this useful faculty is derived from association, and of this Simoni- des and Cicero availed themselves in the early ages. All the abilities of the mind borrow from memory their beauty and perfection; without this, the other faculties of the soul are almost useless. To what purpose are-all our labours in know- ledge and wisdom, if we want memory to preserve and use what we have acquired? What avail all our intellectual or spi- ritual improvements, if they are lost as soon as they are obtain- ed? Memory alone enriches the mind, by preserving what our labour and industry have collected. Without memory, there can be neither knowledge, nor arts, nor sciences. Without the assistance and influence of this power, mankind would expe- rience no improvement in virtue, in morals, or in religion. The soul of man would be but a poor, destitute, naked being, with- out memory. If we except the fleeting ideas of the moment, it would present an everlasting blank. - It is often found, that a fine genius has but a feeble memory; for where the genius is bright, and the imagination vivid, the power of memory may be too much neglected, and lose its im- provement. An active fancy readily wanders over a multitude of objects, and is continually entertaining it with new and tran- sitory images. It runs through a number of new scenes, or new pages, with pleasure, but without due attention; and sel- dom suffers itself to dwell upon any of them long enough for the mind to receive a deep impression, or for the remembrance of the subject to be lasting,” Consequently, many persons of very bright parts, and active spirits, have but short and narrow powers of recollection; possessing riches of their own, they are not solicitous to borrow from the stores of others. When the memory has been almost constantly employed in making new acquirements, and when there has not been a judgment suffi- cient to distinguish what was fit to be remembered, and what was idle, trifling, or needless, the mind has been filled with a wretched heap of words or ideas. In this case, the soul had large possessions, but no true riches. “Whatever,” as Milton says, “old Time, with his huge drag net, has conveyed down to us, along the stream of ages; whether it be shells or shellfish, jewels or pebbles, sticks or straws, sea weeds or mud;” all is treasured up indiscriminately, by those persons who have not the judgment to determine what is to be remembered, and what is to be forgotten. How many excellent judgments and rea- sonings are framed in the mind of a wise and studious man, in a length of years 1 How many worthy and admirable notions has he possessed in life, both by his own reasonings, and by his pru- dent recollections in the course of his reading ! But, alas ! how many thousands of them vanish, and are lost for want of a happy and retentive memory. - - Mr. Locke, speaking of the continual decay of our ideas, beautifully observes, “The ideas, as well as children of our youth, often die before us: and our minds répresent those tombs to which we are approaching; where, though the brass and marble remain, yet the inscriptions are effaced by time, and the imagery moulders away. The pictures drawn in our minds are laid in fading colours, and, if not sometimes refreshed, .vanish and disappear. How much the constitution of our bodies, and the make of our animal spirits, are concerned in this, and whether the tempér of the brain makes this difference, that, in some it retains the characters drawn on it like marble, in others like free stone, and in others little better than sand ; I shall not here inquire: though it may seem probable, that the constitution of the body does sometimes influence the memory; since we oftentimes find a disease quite strip the mind of all its ideas, and the flames of a fever, in a few days, calcine all those images to dust aſid confusion, which seemed to be as lasting as if graved in marble.” * A good memory has these qualiftöations: (1) It is ready to receive and admit, with perfeófºase, the various ideas of words and things which are learned Ör taught 2. It is copious enough to treasure up these ideas in gréat nºtaber and variety. --~~~ I ——-ºkº -- . . 3. *—a —£-— *— * In all these cases, (says Locke,) ideas in theinini quickly fade, and often Vanish quite out of the understanding, leaving no more footsteps or remaining characters of themselves, than shadowsºdó’ flying over fields of corn; and the mind is as void of them, as if they had never been there. 70. 3. It is sufficiently strong, to retain, for a considerable time, those words or thoughts which are committed to its care. 4. It possesses the power of suggesting and recollecting, from the abundance of its store, words or thoughts proper for every oc- casion in life. - - - Rules for Improving the Memory.—Many rules have been given for the regulation of this important faculty: the follow- ing, if attentively practised, will conduce much to the solid and lasting improvement of the memory. Temperance in eating, drinking, and sleep.–The memory de- pends much upon the state of the brain, and therefore what is hurtful to the latter must be prejudicial to the former. Too much sleep clouds the brain, and too little overheats it; there- fore, either of these extremes ought to be avoided. Intemper- ance of all kinds, and excess of passion, have the same ill effects. A clear and distinct apprehension of what we wish to remember. We should understand the subject thoroughly, and fix our view particularly upon its importance. An abridgment of a good book is, sometimes, a very useful exer- cise.—In general we should preserve the doctrines, sentiments, or facts, that occur in reading ; we should låy the book aside, and put them in our own words. Method and regularity are essentially necessary.—Those things are best remembered, the parts of which are methodically dis- posed and mutually connected. Repetition and review.—When a person is hearing a sermon, or a lecture, he should endeavour to recollect the several heads of it, from the beginning, two or three times before the dis- course is finished. The omission or the loss of a few sentences is amply compensated by preserving in the mind the method and order of the whole discourse, in all its most important branches. Discoursing with our companions on what we have been reading, or teaching it to our younger friends, is an excel- lent mode of repetition, and contributes, more than any other perhaps, to assist the memory. The memory gains great ad- vantage by having the objects of our learning drawn out into schemes or tables. The situation of the several parts of the earth is better learned by one day’s consultation with the ter- restrial globe, than by merely reading the description of their situation a hundred times over in books of geography. Writing what we wish to remember once, and giving it due attention, will fix it more in the mind than reading it several times. What we have seen is not so soon forgotten as what we have only heard. What Horace affirms of the mind or passions, is not less applicable to the memory: Sounds which address the ear are lost and die In one short hour; but that which strikes the eye Lives long upon the mind; the faithful sight Engraves the knowledge with a beam of light. , Rhyme. The memory of useful things may receive consi- derable aid, if they are thrown into verse. For the numbers and measures, and rhyme, according to the poesy of different languages, assist us very materially in receiving what is pro- posed to our observation,and in preserving it long in our remembrance. How many of the common affairs of human life taught in early years are indelibly fixed in our memories by the aid of rhyme. - º Initial Letters.—It has sometimes been the practice to im– print names or sentences on the memory, by taking the first letter of every word of that sentence, or of those names, and making a new word out of them. The name of the Maccabees is borrowed from the first letter of the Hebrew words which make the sentence, Mi Camoka, Baelim Jehovah, that is, Who is like thee among the gods?—which was written on their ban- ners. So the word Vibgyor teaches us to remember the order of the seven original colours as they appear by the sun-beams, cast through a prism on white paper, or formed by the sum in a rainbow, according to the different refrangibility of the rays, viz. violet, indigo, blue, green, yellow, orange, and red- Common Place Book.-There have been many different modes of keeping this book offered to our attention, and almost every person has one peculiar to himself. That which Mr. Locke found, after twenty years’ experience, to be the most convenient and advantageous, is thus described. The first page of the book, or, for more room, the two first pages fronting each other, 8 MI 686 M. N. E. DICTIONARY OF MECHANICAL SCIENCE. M o D " ; , - are to serve for a kind of index to the whole, and contain refer- ences to every place or matter therein; in the commodious contrivance of this, so as it may admit of a sufficient Variety of materials, without confusion, all the secret, of the method consists. The manner of it, as laid down by Mr. Locke, will be conceived from the following specimen, wherein what is to be done in the book for all the letters of the alphabet, is here shewn in the first four. . . . . . . A (, 62 A | * o º 14 (l, e 2. 3. ~r— B | { O _j tº ſº, 62 C | 0 u T. & 62 D i () 74. The index of the common place book being thus formed, it is ready for the taking down anything therein. In order to this, con- sider to what head the thing you would enter is most naturally referred, and under which one would be led to look for such a thing; in this head or word regard is to be had to the initial letter, and the first vowel that follows it; which are the charac- teristic letters whereon all the use of the index depends. Sup- pose I would enter down a passage that refers to the head beauty; B, I consider, is the initial letter, and e the first vowel, then looking upon the index of the partition B, and therein the line e (which is the place for all words whose initial is B, and the first vowel e ; as beauty, beneficence, bread, bleeding, blemishes, &c.) and finding no numbers already written to di- rect me to any page of the book where words of that character- ištic have been entered, I turn forward to the first blank page I find, which in a fresh book, as this is supposed to be, will be page 2, and here write what I have occasion for on the head beauty; beginning the head in the margin, and indenting all the other subservient lines, that the head may stand out and shew itself; this done, I enter the page where it is written, viz. 2, in the space Be; from which time the class B e, becomes wholly in possession of the second and third pages, which are consign- ed to letters of this characteristic. Note. If the head be a monosyllable beginning with a vowel, the vowel is at the same time both the initial letter and the characteristic vowel; thus the word Art is to be written in A a. Mr. Locke omits three letters of the alphabet in his index, viz. K, Y, and W, which are supplied by C, I, and U, equivalent to them ; and as for Q, since it is always followed by an u, he puts it in the first place of Z; and so has no Z u, which is a characteristic that very rarely occurs. By thus making Q the last of the index, its regularity is preserved without diminishing its extent. Others choose to retain the class Z u, and assign a place for Q u below the index. If any imagine these hundred classes are not sufficient to $.” all kinds of subjects without confusion, he may 'follow the same method, and yet augment the number to 500, by taking in one or more characteristic to them. But the in- ventor assures us, that in all his collections for a long series of years, he never found any deficiency in the index as above laid down. . . . . - A. The most effectual method of improving the memory is by due and proper, exercise. Our memories will be in a great measure molded and formed, improved or injured, according to the exercise of them. If we never use them, they will he almost lost. Those who are accustomed to converse and read of a few things only, will retain but a few in their memory. Those who are used to remember an event for an hour, and to charge their memories with it no longer, will retain this event but an hour before it vanishes. But, on the other hand, espe- cial care should be taken, that the memory of the learner be not crowded with too great a variety of ideas at one time. This is the way to learn nothing; one idea effaces another. . The Memory can be improved only by moderate exercise.—Such is the opinion of Dr Watts, a high authority in matters of this nature, respecting the improvements of the natural memory. The recollection which ordinary memories possess, appears to be resolvable into two principal sources, the vivacity of the impression, and association. Singularity of impression is gene- rally accompanied with vivacity, but association is the princi- pal expedient for assisting the memory. Thus “when I see the house of my friend, I recollect his family; when I hear of Water- loo, I recollect the overthrow of Napoleon.” - MOAT, or DITch, in Fortification, a deep trench dug round the rampart of a fortified place, to prevent surprises. The brink of the moat next the rampart, is called the scarp; and the opposite one, the counterscarp. A dry moat round a large place, with a strong garrison, is preferable to one full of water; because the passage may be disputed inch by inch, and the besiegers, when lodged in it, are continually exposed to the santly from the rampart into their works. In the middle of dry moats, there is sometimes another small one called lunette, which is generally dug so deep till they find water to fill it. The deepest and broadest moats are accounted the best, but a deep one is preferable to a broad one ; the ordinary breadth is about twenty fathoms, and the depth about sixteen. To drain a mote that is full of water, they dig a trench deeper than the level of the water, to let it run off, and then throw hurdles upon the mud and slime, covering them with earth or bundles of rushes, to make a sure and firm passage. MOBILITY, a contingent property of bodies, but most essential to their constitution. Every body at rest can be put in motion, and if no impediment intervenes, this change may be effected by the slightest external impression. Thus, the largest cannon ball, suspended freely by a rod or chain from a lofty ceiling, is visibly agitated by the horizontal stroke of a swan shot, which has gained some velocity in its descent through the arc of a pendulum. In like manner, a ship of any burden is, in calm weather and smooth water, gradually pull- ed along even by the exertions of a boy. A certain measure of force, indeed, is often required to commence or to maintain the motion; but this consideration is wholly extrinsic, and depends on the obstacles at first to be overcome, and on the resistance which is afterwards encountered. If the adhesion and intervention of other bodies were absolutely precluded: motion would be generated by the smallest pressure, and would continue with undiminished energy. MODE, in Logic, called also syllogistic mood, a proper dis- position of the several propositions of a syllogism, in respect of quantity and quality. Mode, in Philosophy, denotes the manner of a thing's exis- tence. - MODEL, in a general sense, an original pattern, proposed for any one to copy or imitate. This word is particularly in building, as applicable to an artificial pattern made in wood, stone, plas- ter, or other matter, with all its parts and proportions, in order for the better conducting and executing some great work, and to give an idea of the effect it will have when finished. They also use models in painting and sculpture; whence in the acade- mies of painting they give the term Model to a naked man or woman, disposed in several postures, to afford an opportunity to the scholars to design him in various views and attitudes. Models in imitation of any natural or artificial substance, are t bombs, grenades, and other fire-works, which are thrown inces- M O L M O N 687 diction ARY of MECHANICAL SciFNCE. most usually made by means of moulds composed of plaster of Paris. Thus, when a model is to be taken, the surface of the original is first greased, to prevent the plaster from sticking to it. The original is then laid on a smooth table, previously greased, or covered with a cloth to prevent the plaster sticking to it: then surround the original with a frame or ridge of gla- ziers’ putty, at such a distance from it as will admit the plaster to rest upon the table, on all sides of the subject, for about an inch, or as much as is sufficient to give the proper degree of strength to the mould. A sufficient quantity of plaster is then to be poured as uniformly as possible over the whole substance, until it is every where covered to such a thickness as to give a proper substance to the mould, which may vary in proportion to the size. The whole must then remain in this condition till the plaster has attained its hardness: when the frame is taken away, the mould may be inverted, and the subject removed from it; and when the plaster is thoroughly dry, let it be well. seasoned. MODULATION, in Music, the art of conducting harmony, in composition, or extemporary performance, through those keys and modes which have a due relation to the fundamental or original key. . . . : x MODUS DECIMANDI, in Law, is where money, land, or other valuable consideration, has been given, time out of mind, to the minister or parson of any certain place, in the room of tithes. • - MOHAIR, the hair of a kind of goat, frequent about Angora, in Turkey. - MOISTURE, a term sometimes used to denote animal fluids, the juices of plants, or dampness of the air or other bodies. . - MOLE, a name given in the Mediterranean to a long pier or artificial bulwark of masonry, extending obliquely across the entrance of a harbour, in order to break the force of the sea from the vessels that are anchored within. Mole, is also applied to the harbour or haven which is formed by the bulwark above described, which latter is then denominated the mole head. • - MOLECULAE, the same as Ato Ms. MOLLUSCA, in Natural History, the second order of the Linnaean class vermes. They are naked; furnished with ten- tacula, or arms; for the most part inhabitants of the sea; and, by their phosphoreous quality, illuminate the dark abyss of the WaterS. with limbs. - . . MOLOSSES, the thick fluid matter remaining after the su- gar is made, resembling syrup. MOLYBDATES, in Chemistry, salts formed from the molyb- They are colourless, dic acid, and the earths, alkalies, &c. and soluble in water; they have a metallic taste. The prus- siate of potash throws down from several of them a light brown- coloured precipitate. - - MOLYBDENA, or Sulphuret of Molybdenum, occurs mas- sive, disseminated, and rarely crystallized. Its colour is like that of fresh cut metallic lead. It occurs in granular distinct concretions; it is opaque, stains the fingers, and leaves shining traces when drawn over paper; it is very soft, and easily divi- sible in the direction of the laminae. Specific gravity 45 to 47. It is infusible before the blow-pipe, but exhales a sulphureous odour; at a very high heat it melts, gives out white fumes, and burns with a blue flame. It is found in Norway, Sweden, Sax- ony, and in Mont-Blanc in Switzerland. . MOLYBDENUM, a metal of a grayish-white colour, in the form of brittle infusible grains. In the analysis was obtained sulphur, and a whitish powder, which is a metallic oxide, and possesses the properties of an acid. Hitherto this metal is only obtained in grains, the greatest heat has not been sufficient to melt it into a button; its specific gravity is 7-4. MOLYBDIC or Molybdous Acid. (See above.) Molybdic acid combines with alkalies, earths, and several metallic oxides, and forms molybdates, which see. This acid, combined with potash, forms a colourless salt; mixed with filings of tin and muriatic acid, it becomes blue, and precipitates flakes of the same colour, which disappear after some time; 100 parts are composed of 67 molybdenum, and 33 oxygen. MOLYNEAUX, William, a celebrated astronomer and This order is composed of simple animals furnished . mathematician, was born at Dublin, in the year 1666, and died in 1698. . . . . . . . . - - - ... . Mo LYNEAUx, Samuel, son of the former, was also an able astronomer; but his public situation prevented him from pur- suing the subject to the same extent as had been done by his father. . . * * - - . . . . MOMENT, an indefinite small portion of time, having the same relation to duration as a point has to a line. MoMENT, in the Modern Analysis, is the same as Infinitesi- mal, Increment, or Decrement; for an explanation of which see those terms. - - - MOMENTUM, in Mechanics, is the same with impetus, or Quantity of motion, and is generally estimated by the product of the velocity and mass of the body. This is a subject, how- ever, which has led to various controversies between philoso- phers, some estimating it by the mass into the velocity, as stated above, while others maintain, that it varies as the mass into the square of the velocity. But this difference seems to have arisen rather from a misconception of the term, than from any other cause: those who maintain the former doctrine, understanding momentum to signify the momentary impact; and the latter, as the sum of all the impulses till the motion of the body is destroyed. See Force. -> MOMORDICA ELATERIUM. Spirting Cucumber.—The fruit of the Elaterium is a strong cathartic, and very often operates also upwards. Two or three grains are accounted in most cases a sufficient dose. Simon Paulli relates some in- stances of the good effects of this purgative in dropsies: but cautions practitioners not to have recourse to it till after milder medicines have proved ineffectual; to which caution we heartily subscribe. Medicines indeed, in general, which act with vio- lence in a small dose, require the utmost skill to manage them with any tolerable degree of safety: to which may be added, that the various methods of making these kinds of prepara- |tions, as practised by different hands, must needs vary their power. - MIONADES. See DIGITS. - MONARCHY, a government in which the supreme power is invested in a single person. There are several kinds of monar- chies, as, where the monarch is invested with an absolute pow- er, and is accountable to none but God; or limited, where the supreme power is virtually in the laws, though the majesty of government and the administration is vested in a single person. Monarchies are also either hereditary or elective, where the choice depends upon all who enjoy the benefit of freedom, or upon a few persons in whom the constitution vests the power of election. MO NASTERY, a convent, or house built for the reception and entertainment of monks, medicant friars, or nuns, whether it be an abbey, priory, &c. - MONEY, the medium of commerce, commonly metal, and generally of a determined shape and weight to which public authority has affixed a certain value. Money is usually divi- ded into real or effective ; and imaginary, or money of account. Real money includes all coins or species of gold, silver, cop- per, &c. which exist and have currency. Imaginary money, or money of account, is that which has never existed, or at least which does not exist in real specie, but is a denomination invented or retained to facilitate the stating of accounts, by keeping them still on a fixed footing, not to be changed like current coins. . No person is obliged to take in payment any money which is not lawful metal, that is, of silver and gold, except for sums under sixpence. But it was decided in Hilary term, 1790, that bank notes were considered as money, and therefore a proper tender in payment. - English Money of Account, is the pound, shillings, and pence, the pound contains twenty shillings, and the shilling twelve pence. Originally the pound was one pound weight of silver, which was coined into twenty shillings, and a penny was a pennyweight, or the 240th part of a pound. In Scotland, the denominations were the same, but the pound of silver was gra- dually coined into more and more shillings, until at last the pound was reduced to only one-twelfth part of the value of the present pound sterling. - . French Money of Account is francs and centimes: sous still appear sometimes in accounts, and 20 of them make a franc. 688 M O N BYCTIONARY OF MECHANICAL SCIENCE. Money bringing into Court, In sonań actions of law the de- fendant is allowed to pay a sum into court, which he contends is the fair amount of the plaintiff's just demand, and the plaintiff will afterwards proceed at his peril. iſ MONOCEROS, the Unicorn, is a modern constellation formed by that great innovator Heyelius, out of the stellae informes of the ancients.-Boundaries and Contents: N. by Gemini, Canis Minor, and Hydra; E. by Hydra; S. by Argo Navis and Canis Major; and W. by Orion. There are thirty- one stars assigned to this constellation in the Britannic Cata- logue, viz. ten of the fourth magnitude, and the remainder of smaller magnitudes, * * * * * MONOCHORD, in Music, an instrument so called because it is furnished with only one string. Its use is to measure and adjust the ratios of the intervals, which it effects by the means of moveable bridges calculated to divide the chord at the plea- sure of the performer, * MONOCULUS, in Natural History, a genus of insects of the order aptera, There are , about 50 species, separated into sections. - . . MONODON, the Narwhal, in Natural History, a genus of mammalia, of the order cetae. The only genus of this species is M. monoceros, or the unicorn narwhal, found in the northern seas, and generally of the length of twenty feet from the mouth to the tail; from a socket in the upper jaw on one side, a tooth somewhat resembling a horn grows in a perfectly straight di- rection, and a wreathed or screw-like form, to the length of six, and occasionally nine or ten feet, of a light yellow colour, and terminating in a sharp point, a circumstance by which it is discriminated from every other species of whales. The inci- pient protrusion of a second tooth on the other side of the jaw is generally perceivable, and in some instances, though rarely, both advance to maturity. The narwhals subsist principally upon flat-fish. They are seldom observed in the open sea, and frequent the unfrozen spots near the coasts of the arctic re- gions. They are taken by the Greenlanders in great abundance by the harpoon; their flesh is eaten prepared in various ways, and the oil and intestines are also articles in great request. The tendons are split into thin fibres, serving the purposes of thread, and the teeth are used sometimes for hunting horns, and more frequently as pillars and gate posts in houses. These horns were formerly considered as indicative of royal state and magnificence, being employed as the ornaments of palaces. MONOGRAM, a character or cipher, composed of one, two, or more letters interwoven; being a kind of abbreviation of a name, anciently used as a seal, badge, arms, &c. The use of arms is very ancient, as appears from Plutarch, and from some Greek medals of the time of Philip of Macedon and Alexander his son. The Roman labarum bore the monogram of Jesus Christ, which consisted of two letters, a P placed perpendicu- larly through the middle of an X, as we find it on many medals in the time of Constantine, these being the two first letters of the word XPIXTOX. Thus, under the Eastern empire, it is usual to find MIK," which are the monogram of Mary, Jesus, Constantine. MONOMIAL, in Algebra, is a quantity consisting only of one term; as a r, 3 batº, &c. MONOTONY, an uniformity of sound, or fault in pronunci- ation, when a long series of words are delivered in one unvaried tone. MONS MENSAE, the Table Mountain, a modern asterism, situated between the Southern Pole of the World and the Ecliptic, contains thirty stars: this constellation culminates with Auriga and Orion. * MONSOON, a species of trade wind in the East Indies, which, for six months blows constantly the same way, and the contrary way the other six months. However, it ought to be observed, that the points of the compass from whence the mon- soons blow, as well as the times of their shifting, differ in dif- ferent parts of the Indian ocean. The cause of monsoons is this : when the sun approaches the northern tropic, there are countries, as, Arabia, Persia, India, &c. which become hotter, and, reflect more heat than the seas beyond the equator, which the sun has left; the winds, therefore, instead of blowing from thence to the parts under the equator, blow the contrary way; and when the sun leaves those countries, and draws near the other tropic, the winds turn about, and blow on the opposite point of the compass, * * MONTGOLFIER, a name sometimes given to those bal- loons which receive their buoyancy from the burning of com- bustible materials; being thus denominated after the name of their inventor, by which name they are also distinguished from the inflammable air-balloons. See Aerost Ation. MONTH, the twelfth part of the year, and is so called from the moon, by whose motions it was regulated, being properly the time in which the moon runs through the zodiac. The lunar month is either illuminative, periodical, or synodical. Illuminative Month, is the interval between the first appear- ance of one new moon and that of the next following. As the moon appears sometimes sooner after one change than after another, the quantity of the illuminative month is not always the same. The Turks and Arabs reckon by this month. Lunar Periodical MoMTH, is the time in which the moon runs through the zodiac, or returns to the same point again; the quantity of which is 27d 7h 43m 88. Lunar Synodical MonTH, called also a lunation, is the time between two conjunctions of the moon with the sun. or between two new moons; the quantity of which is 294 12.44 m 3s 11". The ancient Romans used lunar months, and made them alter- nately of twenty-nine and thirty days. They marked the days of each month by three terms, viz. Calends, Nones, and Ides. Solar Mont H, is the time in which the sun runs through one entire sign of the ecliptic ; the mean quantity of which is 30° 10' 29m 5*, being the twelfth part of 365d 5h49m, the mean solar year. Astronomical or Natural Month, is that measured by some exact interval corresponding to the motion of the sun or moon; such are the lunar and solar months above mentioned. Civil or Common MoMTH, is an interval of a certain number of whole days, approaching nearly to the quantity of some astronomical month. These may be either lunar or solar. The Civil Lunar MonTH consists alternately of twenty-nine and thirty days. Thus will two civil months be equal to two astronomical ones, abating for the odd minutes; and so the new moon will be kept to the first day of such civil months for a long time together. This was the month in civil or common use among the Jews, Greeks, and Romans, till the time of Julius Caesar. - The Civil Solar Month, consisted alternately of thirty and thirty-one days, excepting one month of the twelve, which con- sisted only of twenty-nine days; but every fourth year of thirty days. The form of civil months was introduced by Julius Caesar. Under Augustus, the sixth month, till then from its place called Sextilis, received the name Augustus, now August, in honour of that prince ; and to make the compliment still §reater, a day was added to it, which made it consist of thirty- one days, though till then it had only contained thirty days; to compensate for which, a day was taken from February, mak- ing it consist of twenty-eight days, and twenty-nine every fourth year. Such are the civil or calendar months now used through Europe. . . . MONTH, in Law, is generally a lunar month of twenty-eight days, unless otherwise expressed. MONTUCLA, John Etien Ne, a celebrated French mathema- tician, was born at Lyons, September 5, 1725; and very early in the College of the Jesuits acquired a very intimate knowledge of the Latin and Greek languages, to which he added also several modern languages, as the Italian, English, German, and Dutch ; which, joined to a very complete know- ledge of the mathematical and philosophical sciences, and a remarkable accuracy of research, eminently qualified him for the performance of that work by which he is most distinguished, and by which he has laid a lasting obligation on every admirer of these sciences, viz. his “Histoire des Mathematiques,” which first appeared in 1758, in 2 vols. 4to. and which has been since, viz. in 1802, republished, and augmented to 4 vols. 4to. by Lalande ; the additions being principally drawn from the numerous manuscript notes left by Montucla at the time of his death, which happened at Paris, December 18, 1799. MONUMENT, in Architecture, a building destined to pre- serve the memory, &c. of a person who raised it, or for whom it was raised; as, a triumphal arch, a mausoleum, a pyramid, &c. M O O M O O 689 D1C'TIONARY OF MECHANICAL SCIENCE, r and irregular. 27° 7' 43* 11":5; but this period is variable, and a comparison the earth. and this phenomenon is called her libration in latitude. * M001), or Mode, in Grammar, the different manner of con- , jugating verbs, serving to denote the different affections of the mind. - - MOON, Luna, in Astronomy, one of the heavenly bodies, the constant attendant of our earth, about which she revolves as a centre, illuminating us by her reflected rays in the absence of the sun. The principal elements and phenomena of this body are thus stated by Mr. Baily, in the Philosophical Maga- zine for January, 1812, in a very neat and useful synopsis of astronomy, drawn principally from the Systeme Du Monde of Laplace. The motions of the moon are exceedingly eccentric She performs her mean sidereal revolution in of the modern olaservations with the ancient proves incontes- tably an acceleration in her mean motion. Her mean tropical revolution is 270 7h 43m 4'-7, and her mean synodical revolution 29d 12h 44m 2'.8. Her mean distance from the earth is 29.982.175 times the diameter of the terrestrial equator, or about 237,000 miles. The eccentricity of her orbit is 0548553; the mean dis- tance from the earth being taken equal to unity; but this eccentricity is variable in each revolution. Her mean longitude, at the commencement of the present century, was in 3° 21° 36'42"-1. Her velocity varies in different parts of her orbit; she is swiftest in her perigee (or point nearest the earth,) and slowest when in her apogee (or point farthest from the earth); her mean diurnal velocity is equal to 13° 10' 34"-9, or about thirteen times greater than that of the sun. The greatest equation of her centre is 6° 17' 54".5. The mean longitude of her perihelion was, at the commencement of the present cen- tury, in 8s 26° 6' 5"1; but the line of the apsides has a motion, according to the order of the signs. The period of a sidereal revolution of the apsides, is 3232d 13h 56' 16"-8, or nearly nine years. The period of a tropical revolution of the apsides, is but 3231d 11h 24'8".6. But these periods are not uniform, for they have a secular irregularity, and are retarded whilst the motion of the moon itself is accelerated. The period of an anomalistic revolution of the moon is 27d 13h 18' 37"'4. Her orbit is inclined to the plane of the ecliptic in an angle of 5°9'; but this inclination is variable. The greatest inequality, which sometimes extends to 8' 47":51, is proportionai to the cosine of the angle on which the inequality in the motion of the nodes depends. Her orbit, at the commencement of the present century, crossed the ecliptic in 0° 15° 55' 26"3; but the place of her nodes is variable; these having a retrograde motion, and make a sidereal revolution in 6793d 10h 6' 30"-0, or in about 18:6 Julian years. This variation, however, is subject to many inequalities; of which, the greatest is proportional to the sine of double the distance of the moon from the sun, and extends to 1937'45"-0 at its maximum. A synodical revolu- tion of the nodes is performed in 346d 14h 52' 43".6; but the motion of the nodes is subject also to a secular inequality, dependent on the acceleration of the moon's mean motion. The rotation of the moon on her axis is equal and uniform, and is performed in the same time as the tropical revolution in her orbit; whence she always presents nearly the same face to But as the motion of the moon in her orbit is periodically variable, we sometimes see more of her eastern edge, and sometimes more of her western edge; which appear- ance is called the libration of the moon in longitude. The axis of the moon is inclined to the plane of the ecliptic in an angle of 88°29' 49"; in consequence of which position of the moon, her poles alternately become visible to and obscured from us; There is also another optical deception, arising from the moon being seen from the surface of the earth, instead of the centre, which is called her diurnal libration. Excellent drawings of the moon have been made by Tobias, Mayer, and Russel; but the most accurate and complete are those of Schroeter, who has given highly magnificent views of several parts of the moon's surface. The most favourable time for viewing the lunar disc, is when she is about five days old; the irregularities in her surface being then the most conspi- Cºl OUIS, ... " It is impossible to say what those unenlightened portions, observable in the disc, are, or what they may have been, but we * help thinking that our earth would assume nearly the same appearance, if all the lakes and seas were removed; and who can say but that this may have been the case in the lunar regions? Astronomers formerly supposed, that the dark part of the moon's surface were large lakes and seas, but it is obvious, on an attentive observation with a good telescope, that there are ridges and unevennesses in those parts, which plainly indicate that they are not fluid but solid, like the other parts of her surface; there is, therefore, very little of any fluid matter in this luminary, and hence probably is the reason that her atmosphere is so different from our own ; if, indeed, this can be justly inferred from the circumstances usually adduced as arguments in favour of this hypothesis, which appears very doubtful. We have observed, that mountains may always be seen on the surface of the lunar disc; and even volcanoes have been frequently observed, from which some philosophers have supposed the aëroliths, that at times fall to the earth, to have been projected; which it appears, from computation, would only require a velocity of about 8200 feet per second, to cause them to pass from this body to the earth. See AstroNoMY. Acceleration of the Moon. See AcceleRAtion. ~ Age of the Moon, is the number of days since the new moon, which is found by the following rule:—To the epact add the number and day of the month, which will be the age required, if less than thirty; and if it exceed thirty, subtract this number from it, and the remainder will be the age. See EPAct. Harvest Moon, is a remarkable phenomenon relating to the rising of this luminary in the harvest season. During the time she is at the full, and for a few days before and after, in all about a week, there is less difference in the time of her rising between any two successive nights at this than at any other time of the year. By this means she affords an immediate supply of light after sun-set, which is very beneficial in gather- ing in the fruits of the earth; and hence it is, that this lunation has been termed the harvest moon. In order to conceive this phenomenon, it may first be considered, that the moon is always opposite to the sun when she is full; that she is full in the signs Pisces and Aries in our harvest months, these being the signs opposite to Virgo and Libra, the signs occupied by the sun about the same season; and because those parts of the ecliptic rise in a shorter space of time than others, as may easily be shewn and illustrated by the celestial globe, consequently when the moon is about her full in harvest, she rises with less difference of time, or more immediately after sun-set, than when she is full at other seasons of the year. Moon Dial, is a dial which shews the hours of the night by the light of the moon. - - MOOR, To, to confine or secure a ship in a particular sta- tion by chains or cables, which are either fastened to the adjacent shore, or to anchors in the bottom ; a ship is never said to be moored when she rides by a single anchor. To MooR Across, is to lay out one of the anchors on one side, or athwart a river, and another on the other side right against it. To Moor Along, is to have an anchor in the river, and a hawser on shore. To Moor a Cable each way, is performed by dropping one anchor, veering out two cables’ lengths, and letting go another anchor from the opposite bow; the first is then hove in to one cable, while the latter is veered out as much, whereby the ship rides between the two anchors, equally distant from both. This is usually practised in a tide-way, in such manner that the ship rides by one during the flood, and by the other during the ebb. ... ', To MooR Head, or Head and Stern. This operation may be performed by two methods:—A ship may be secured by an- chors before her, without any behind; or she may have anchors out, both before and behind her; or her cables may be attached to posts, rings, or moorings, which, answer the same purpose. When a ship is moored by the head with her own anchors, they are disposed according to the circumstances of the place where she lies, and the time she is to continue therein. Thus, whenever a tide ebbs and flows, it is usual to carry one anchor out towards the flood, and another towards the ebb, particu- larly where there is little room to range about; and the anchors are laid in the same manner, if the vessel is moored head and stern in the same place. The situation of the anchors in a road or bay, is usually opposed to the reigning winds, or to . those which are most dangerous, so that the ship rides therein 8 N - . 690 M. O. R. M O R DICTIONARY OF MECHANICAL SCIENCE. with the effort of both her cables. Thus, if she rides in a bay or road which is exposed to a northerly wind and heavy soa from the same quarter, the anchors passing from the opposite bows, ought to lie east and west from each other; hence both the cables will retain the ship in her station with equal effort against the action of the wind and sea. MOORE, SIR JonAs, a respectable mathematician, fellow of the Royal Society, and surveyor-general to the ordnance, was born at Whitby, in Yorkshire, in 1620. He was author of several works, but is more deservedly remembered for the support and protection which he rendered to the science, than for any immediate improvement or discovery of his own; the important offices that he filled engaging too much of his time to allow him to follow the subject so far as he might otherwise have done. To him we owe the first establishment of the Royal Observatory at Greenwich, and the appointment of Mr. Flam- stead to that important office; as also for the institution of the mathematical school belonging to Christ Hospital ; for the use of which, he composed a part of a mathematical course, but died before it was completed, about the year 1681. MOORINGS, are an assemblage of anchors, chains, and bridles, laid athwart the bottom of a river or harbour, to ride the shipping therein. These anchors have generally but one fluke, which is sunk in the river near low-water mark. Two anchors, being thus fixed, on the opposite sides of the river, are furnished with a chain extending across from one to the other; in the middle of which is a large square link, whose lower end terminates in a swivel, to which are attached the bridles, which are short pieces of cables well served, whose upper ends are drawn into the ship, and secured to the bitts, &c. By this means the vessel veers round very readily, according to the change of the wind or tide; in some places, however, particularly in rivers, each ship takes in a bridle astern, also, by which she becomes moored head and stern. MOOT, a difficult case argued by the young barristers and students at the inns of court, by way of exercise, the better to qualify them for practice, and to defend the causes of their clients. - MORALITY, the science and doctrine of morals, otherwise called ethics. - MORAVIANS, a denomination of Christians, whose episco- pal and church government is conducted with great form and regularity. Questions of dispute are settled by ballot, and in cases of real or supposed importance are often decided by lot; the lot is deemed a solemn appeal to heaven, and is made use of with great seriousness. They have oeconomies, or choir-houses, where they live together in community; the single men and single women apart, widows and widowers apart, each under superintendence of elderly persons of their own class. The Moravians are very strict in their attention to the youth of both sexes, and never suffer them to come together, or marry without the previous consent of the church, and as the lot must be cast to-sanction their union, each receives his partner as a divine appointment. In doctrine the Moravians appear to be inclined to Sabellianism. They address all their prayers to Jesu, or the Lamb. They reject the use of the term Trinity. In zeal tempered with modesty, and in silent perseverance in attempt- ing to convert the heathen world to Christianity, they were un- equalled, having formed for this purpose settlements in Green- land, America, the West Indies, the Cape of Good Hope, the East Indies, &c. * MORBID, among Physicians, signifies diseased or corrupt, a term applied either to an unsound constitution, or to those parts or humours that are infected by a disease. MORDANT, in Dyeing. When a substance to be dyed has little or no attraction to the matter on which the colour depends, so as either not to be capable of abstracting it from its solvent, or of retaining it with such force as to form a permanent dye, then some intermediate substance is used which acts as a bond of union between them : this substance is called a mordant. MOREL. Phallus Esculentus.-The morel grows in wet banks and moist pastures. It is used by the French cooks, the same as the truffle, for gravies, but has not so good a flavour: it is in perfection in May and June. MORMY RUS, a genus of fishes of the order abdominales. There are nine species, mostly inhabitants of the river Nile. in the city and liberties of Westminster. MOROCCO, a fine kind of leather, prepared of the skin of an animal of the goat kind, and formerly imported from th Levant, Barbary, &c. but now made in England. * * MOROXYLATES, in Chemistry, a genus of salts, of which there are two species, viz. 1. The moroxylate of lime, found on the bark of the mulberry-tree, crystallized in short needies. Its taste resembles succinic acid. When heated, it swells, and emits a vapour which irritates the organs of smell. Its solution precipitates acetate of lead, nitrate of silver, and nitrate of mercury. 2. M. of ammonia, obtained by pouring carbonate of ammonia into the solution of the moroxylate of lime. This so- lution, when evaporated, yields crystals of moroxylate of am- mónia in long slender prisms. MOROXYLIC AcID, discovered by Dr. Thompson on the bark of the morus alba, or white mulberry, growing at Palermo in Sicily. It has the taste of succinic acid; is not altered by exposure to the air; but dissolves readily in water and alcohol. It does not precipitate the metallic solutions like its salt. MORRO, is a term for headland or promontory on the coasts ; Chili and Peru, in South America, on the South Pacific C6 aſl. MORTALITY, BILLs of, registers of the number of deaths or burials in any parish or district. The London bills of mor- tality are founded upon the reports of the sworn searchers, who view the body after decease, and deliver their report to the parish clerk. The parish clerks are required, under a penalty for neglect, to make a weekly return of burials, with age, and disease of which the person died, a summary of which account is published weekly ; and on the Thursday before Christmas- day, a general account is made up for the whole year. The total number of parishes now comprehended in the London bills of mortality is 146. They are divided into ninety-seven parish- es within the walls, sixteen parishes without the walls, twenty- three out parishes in Middlesex and Surrey, and ten parishes They give the ages at which the persons die, a list of the diseases and casualties by which their death was occasioned ; but little dependence can be placed upon the list of diseases, except with respect to some of the most common and determinate. MORTAR, a preparation of lime and sand mixed up with water, which is served as a cement, and is used by masons and bricklayers in building of walls of stone and brick. See LIME. The best mortar for resisting water is made by mixing with lime, puzzolano, a volcanic sand brought from Italy. Basaltes may be substituted in its stead. MoRTAR, in Chemistry and Pharmacy, an utensil very use- ful for the division of the bodies by percussion, trituration, &c. Mortars are of different shapes and sizes, and the matter intended to be broken in them is struck with a pestle made of wood, iron, or marble, according to the different degrees of hardness. MORTAR, a piece of artillery, shorter and wider than a cannon, and having a chamber less than the size of its bore. It is used to discharge bombs, or shells and carcasses into a fortified place. The bomb, or shell, is a great hollow ball filled with powder, which falling into a fortification, &c. destroys the most substantial buildings by its weight, and, bursting asunder, creates the greatest mischief and disorder by its splinters. To prevent the shell from bursting at the first moment of discharge, it is furnished with a fuse, which continues burning during its flight; and to increase the weight of its fall, the mortar is ele- vated to a considerable angle above the horizon. The interior part of this piece of artillery is called the bore, wherein the bomb is lodged ; the inner part of the bore, which is diminished towards the breech, and contains the powder, is termed the chamber. The chambers of mortars are extremely different in their figures, and each of these figures is defended by better or worse arguments. Thus they are spherical, cylindrical, conical, bottled, or concave. Indeed, nothing appears to be less deter- mined upon true principles or experiments than the propor- tions of the several parts of a mortar. As the sea mortars, or those which are placed in the bomb-vessels, are generally fixed at a much greater distance from the object than is required at shore, they are made somewhat longer and much heavier than the land-mortars. Mr. Muhler, in his Treatise on Artillery, very justly observes, that the breech of our thirteen-inch sea- M O R. M. O. R. DICTIONARY OF MECHANICAL SCIENCE. 691. mortars is loaded with an unnecessary weight of metal: the chamber thereof contains thirty-two pounds of powder, and at the same time they are never charged with more than twelve or fifteen pounds by the most expert officers, because the bomb- vessel is unable to bear the violent shock of their full charge. Thus the action of the powder is diminished by the vacancy left in the chamber, which is never half filled. As a charge of twelve or fifteen pounds at most is therefore sufficient, it is ..evidently proved, by the theory of powder, that this will pro- duce the greatest effect when discharged from a mortar with a cylindrical ehamber. He also proves, by a variety of experi- ments made by Captain Desaguliers and himself, that the conical chamber, now used, is considerably inferior to the cylindrical one with the last discharge of powder. To facili- tate the use of the mortar, it is placed in a solid carriage of timber called the bed, whose different parts are strongly bolted together. By means of this it is firmly secured in its situation, so that the explosion of the powder may not alter its direction. In the middle of the upper side of this carriage are two semi- circular notches to receive the trunnions; over these are fixed two very strong bands of iron, called the cap squares, the middle of which is bent into a semi-circle, to embrace the trunnions, and keep them fast in the mortar bed. The cap- squares are confined to the timber work by strong pins of iron, called the eye-bolts, into whose upper ends are #". the keys, chained beneath them. On the fore-part of the bed a piece of timber is placed transversely, upon which rests the belly of the mortar on that part which contains the chamber. The elevation of this piece, which is called the bed bolster, is used to elevate and support the mortar whilst firing. These beds are placed upon very strong beds of timber, which are fixed in the bomb-ketch. They are securely attached to the frames by means of a strong bolt of iron called the pintle, pass- ing perpendicularly through both, and afterwards through one of the beams of the vessel. Thus the pintle which passes through the whole in the centre, serves as an axis to the bed, so that the mortar may be turned about horizontally as occa- sion requires. The shell, as already observed, is a great hol- low ball, charged with powder. The lower part of the shell is thickest, by which it becomes heavier on that side, and accord- ingly falls thereon, and never on the fuse. It is also the better enabled thereby to resist the impression of the powder, by which it is discharged from the mortar. Both of these rea- sons, however, Mr. Muhler conceives to be immaterial, be- cause nothing but an absolute stoppage of the air can exhaust the fuses, as their composition enables them to burn in water as well as in air or earth, and the explosion of the mortar would not, in his opinion, be able to break them, if they were equally thick every where. The most proper quantity of powder to charge a shell is probably two-thirds of the weight which would fill the cavity. The fuse is generally a conical tube formed of birch, willow, or some dry wood, and ſilled with a composition of sulphur, salt-petre, and mealed powder. The shell being charged, this fuse is inserted in the cavity through the fuse- hole, and when fired, communicates the fire to the powder in the shell. The fuses are charged with great care, that nothing may prevent them from communicating the fire to the powder in the centre of the bomb. They are driven into it so as that only an inch and a half comes out beyond the fuse-hole, and then the shell is said to be fixed. These fuses are also charged long before there is occasion to use them; and that the compo- sition with which they are filled may not fall out or be damaged by growing damp, the two ends are covered with a compo- sition of tallow mixed either with pitch or bees-wax. When the fuse is to be put into the shell, the little end is opened or cut off, but the great end is never opened till the mortar is to be fired. The proper quantity of gunpowder being put into the chamber, if there be any vacant space, they fill it up with hay: some choose a wooden plug; over this they lay a turf, some a tompion fitted to the bore of the piece, and lastly the bomb; taking care that the fire be in the axis thereof, and the orifice be turned from the muzzle of the piece. What space remains is to be filled up with hay, straw, turf, &c. so as that the load umay not be exploded without the utmost violence. This done, the charge is covered with a wad well beat down with the rammer. After this the fixed shell is placed upon the wad, as near the middle of the mortar as possible, with the fuse-hole uppermost, and another wad pressed down close upon it, so as to keep the shell firm in its position. The officer then points the mortar, or gives it the inclination necessary to throw the shell to the place designed. When the mortar is thus fixed, the fuse is opened; the priming-iron is also thrust into the touch-hole of the mortar to clear it, after which it is primed with the finest powder. This done, two of the matrosses or sailors, taking each one of the matches, the first lights the fuse, and the other fires the mortar. The shell, thrown out by the explosion of the powder, is thrown to the place intended; and the fuse, which ought to be exhausted at the instant of the shell’s falling, inflames the powder contained therein, and bursts it into splinters; which, flying off circularly, occasion incredible mischief wheresoever they reach. The following are the necessary orders before a bombard- ment by sea :-When any fixed shells are issued from the tenders, the artillery people on board are immediately to fix others in their room, and are always to keep in their tenders the same number they had at first. 2. The shells are to be fixed in the boats appointed to carry them, provided the wea- ther permits; otherwise, in the safest place on deck, and to be kited or lowered down into a spare rack, which must be in each boat for that purpose. While the shells are fixing, the powder-room is to be shut, the hatches Paid and well secured against fire, and the place where they are fixed is to be well watered. 3. The shells being carefully examined, in order that no spike be left therein, by which the fuse may be split, the fuses are to be cut the whole length, and to be set home into the shells very strongly. 4. No shells fixed during the service are to be kited; but if any should be left when the service is over, they are immediately to be kited. 5. The powder in the bomb-vessels is to be used first, and none to be opened or measured out except in the captain’s cabin, the door of which is to be kept shut during the whole time, and covered with tanned hides to make it as secure as possible. 6. The fixed shells in the boats are to be likewise covered from fire or wet, with hair-cloth and tanned hides with the utmost care. 7. If the service is carried on at night, all the powder is to be ready measured out in cartridges, which may be kept in the powder- magazine and captain's cabin in the empty powder barrels and powder bags; arid all the shells requisite to be ready. The tin tubes, one powder horn, and the port-fires, also the punches and bits for the vents, are to be kept in the captain's cabin. 8. No fire, nor light, except match and port-fires, to be on board either bomb-vessel or tender during the service. 9. The cap- tain's cabin and the passage to it, also the way to the maga- zine and decks, are to be constantly watered. 10. The sponges for the mortars are to be all examined and tried, and if too large, they are to be cut so as to enter easily. 11. The vents of the mortars are to be examined, and the punches and tubes tried in them. 12. A laboratory chest is to be on board each bomb-vessel in the captain's cabin, in which all the small stores are to be kept. 13. Two tubs of water are to be on deck for the lightest port-fires and match, which must be con- stantly held in them till ordered to fire. 14. Two careful men are also to be appointed for this service, who are to do nothing else on any account. 15. Two careful men of the artillery are to be left on board each tender, for the filling and fixing of the shells. 16. Application must be made to the admiral for two men-of-war's boats to attend on each bomb-ketch and tender for carrying shells and stores. One of these is to be loaded with fixed shells, which, when sent to the bomb-vessel, must remain with her until they are all taken out, which should be only as they are wanted for loading the mortars: it is then to return to the tender. The other boats, meanwhile, will be receiving more fixed shells, and on the signal given from the bomb-ketch for more shells, must immediately repair to her with them. 17. A gang of warrant officers and eight seamen are to be at each mortar, and to give whatever assistance may be required. 18. A gang from the navy, with a careful warrant officer and non-commissioned officer of the artillery, are to have the charge between decks on board each bomb-vessel and tender, to get up the fixed shells that are in the rack, and a careful person is to remain constantly at the powder-room door, which must be kept shut as much as possible. 19. When 692 M O R. M O R. DICTIONARY OF MECHANICAL SCIENCE any powder is wanted from the ender for loading the mortar, it should be measured out in the tender, and a proper charge put into paper cartridges, upon which should be written the quantity and the mortar for which it is allotted. In shooting with mortars, the following general rules should be always observed :–1. To measure the distance of the, ob- ject aimed at. 2...That the bombs be of equal weight, other- wise the shots will vary. 3. That the carriage be on an exact level to prevent its leaping. 4. That the powder with which the piece is charged be always of the same strength and quan- tity. 5. That the charge be always equally rammed down. 6. That the wads be always of wood, tompions, or oakum. 7. That the fuses be fresh made the days on which they are to be used, and that they be of a composition proportionable to the range of the shot in the air, so that the bomb may break at the very moment of, or soon after, its fall; which composition must be such as not to be extinguished though it fall in water, but continue burning till the bomb breaks.—If the service of mor- tars should render it necessary to use pound shots, two hundred of them, with a wooden bottom, are to be put into the thirteen- inch mortar, and a quantity of powder not exceeding five pounds; and one hundred of the above shot, with two pounds and a half of powder for the ten-inch mortar, or three pounds at most. One inch of fuse burns four seconds and forty-eight arts. - . - . The following table exhibits the weight of the sea-mortars and shells, and also of their full charge :- Weight of - } Powder con- - Weight of powder Nature of the tained in the Weight of the the shell contained mortar. chamber mortar. when in the - when full. fixed. shell. - lb., oz. || C. qr. Ib. lb. lb. oz. 10-inch howitzer. 12 0 31 2 26 0 0 0 13-inch mortar. - 30 0 81 2 1 . I98 7 0. 10-inch mortar. . 12 () 34 2 1 1 93 0 0 . The Howitzer is a sort of mortar, which is to be fixed hori- zontally like a cannon, and has, like the cannon, a wheel car- riage. These pieces are very rarely used in the sea service. For further particulars, see the articles BoMB, RANGE, &c. MoRTAR.-Mr. Carey's Improved Plan of a Gun and Mortar Boat, with Sheer Bowsprit. A port-hole is cut through, and a port fitted, the same as the lower deck port. Combings and gratings are fitted over the gun, which runs in until wanted to the main mast. Over the gratings, a tarpauling is thrown in bad weather; alongside of the mast, a winch, which runs the gun in and out, and hoists the mainsail and foresail, and also tops the sheer bowsprit up when about to fire the gun. With two men, a boy, and an engineer, having a steam-engine on board, and a long 32-pounder with a chamber in the gun, a frigate, might be destroyed in a calm, or a seventy-four dis- masted and sunk. With a steam-engine on board, and if the larger vessel attempted to hoist out their boats to board the mortar boat, she could run away from them; and, a gun fitted right aft, could destroy the boats and their crews. The sheer bowsprits shew their utility, as no bowsprit shrouds are want- ing, nor bobstay, the jib-tack forming the bobstay. Carey, of Bristol, fitted a boat in this way, when at his majesty’s yard at Gibraltar, which Lord Nelson highly approved of. Description. a a the sheer bowsprit; b the port and port- hole; c the 32 long pounder, with a chamber; in bad weather the gun is run under, a grating which is over it upon deck; d a winch to heave the gun out and in ; after firing, hoist the main sail, and heave up the sheer bowsprit; e the jib-stay and topping lift, to raise the sheers when going to fire.—N. B. A magazine is placed midway between the gun and the ship's side, which cannot be shewn in the above view. - MORTGAGE, signifies a pawn of lands or tenements, or any thing immoveable, laid or bound for money borrowed, to be the creditor’s for ever, if the money be nºt paid at the day agreed upon. Mortgages are either in fee or for term of years, and the mortgager was formerly considered, as tenant at will to the mortgagee, but he is now considered to have no legal estate whatever in the land. The last and best improvement of mort- gages is the mode now adopted, where the mortgage is made for a term of years, that the mortgager, if he has also the fee, covenants to convey the ſee to the mortgagee and his heirs, or any person whom he may appoint in case of default in pay- ment of the money. . Although, after breach of the condition, the estate is absolute at common law in the mortgagee, yet a right of redemption subsists in equity, which is called the equi- ty of redemption, from the benefit of which the heir of the mort- gager cannot be excluded by any covenant, provided the ori- ginal intent is to morgage the estate, and not to sell it at first. This right goes to those who would have had the estate, if it had not been incumbered. Although therefore the mortgage is forfeited, yet a court of equity will allow the mortgager at any reasonable time, to recall or redeem the estate, paying the prin- cipal, interest, and costs. This, however, is not allowed, if the mortgagee has been twenty years in possession. The heir at law may have the mortgage redeemed out of the personal assets in the first place as far as they will extend. This privilege is also allowed to the person to whom land mortgaged is devised. Where a mortgager conceals prior incumbrances upon making a second mortgago, he loses the equity of redemption. MORTISE, or MoRtoise, in Carpentry, a kind of joint, wherein a hole of a certain depth is made in a piece of timber, which is to receive another piece called a tenon. MORTMAIN, signifies an alienation of lands and tenements, to any guild, corporation, or fraternity, and their successors, as bishops, parsons, vicars, &c., which may not be done without the king's license, and the lord of the manor; or of the king alone, if it is immediately holden of him. - MORUS, the Mulberry Tree, a genus of the tetrandria order, in the monoecia class of plants; natural order scabridae. There are seven species, viz. 1. The migra, or common black-fruited mulberry-tree, rises with an upright, large, rough trunk, divid- ing into a branchy and very spreading head, rising twenty feet high or more. The fruit has the common qualities of the other sweet fruits, abating heat, quenching thirst, and promot– ing the grosser secretions; an agreeable syrup made from the juice is kept in the shops. The bark of the roots has been in considerable esteem as a vermifuge; its taste is bitter, and somewhat astringent. 2. The alba, or white mulberry-tree, rises with an upright trunk, branching twenty or thirty feet high. Considered as fruit trees, the nigra is the only proper sort to cul- tivate here ; the trees being not only the most plentiful bearers, but the fruit is larger and much finer flavoured than that of the white kind. Mulberry-trees are noted for their leaves afford- ing the principal food of the silkworm. The leaves of the white species are preferred for this purpose in Europe ; but in Chi- na, where the best silk is made, the worms are fed with those of the morus tartarica. The advantages of white mulberry trees are not confined to the nourishment of worms: they may be cut every three or four years like sallows and poplar trees to make fagots; and the sheep eat their leaves in the winter, before they are burnt. This kind of food, of which they are ex- tremely fond, is nourishing ; it gives a delicacy to the flesh and a fineness to the wool. The paper mulberry, is so called from the paper chiefly used by the Japanese being made of the bark of its branches. The leaves of this species also serve for food to the silkworm, and is now cultivated with success in France. It thrives best in sandy soils, grows faster than the common mulberry, and at the same time it is not injured by the cold. The inhabitants of Japan make paper of the bark, culti- M o S M O T DIUTIONARY OF MECHANICAL SCIENCE. 693 wate the trees to this purpose on the mountains, much after the same manner as osiers are cultivated with us, cutting down the young shoots in December, after the leaves are fallen; these being divided into rods of three feet in length, are gathered in bundles to be boiled; they are placed erect and close in a large copper, properly closed, and the boiling continued till the separation of the bark shews the naked wood, after which, by a longitudinal incision, the bark is stripped off and dried, the wood being rejected. To purify the bark, they keep it three or four hours in water; when it is suſliciently softened, the cuticle, which is of a dark colour, together with the greenish surface of the inner bark, is pared off, at the same time the stronger bark is separated from the more tender, the former making the whitest and best paper; the latter a dark and inferior kind. The finest and whitest cloth, worn by the principal people at Otaheite, and in the Sandwich islands, is made of the bark of this tree. The bread-fruit tree makes a cloth inferior in white- ness and softness, worn chiefly by the inferior people. Cloth is also made of a tree resembling the wild fig-tree of the West Indies; it is coarse and harsh, the colour of the darkest brown paper; but it is the most valuable, because it resists the water. This is perfumed and worn by the chiefs as a mourning dress in Otaheite. The tinctora is a fine timber tree, and a principal ingredient in most of our yellow dyes, for which it is chiefly imported into Europe. MOSAIC, or Mos AIC. WoRK, an assemblage of little pieces of glass, marble, precious stones, &c. of various colours, cut square, and cemented on a ground of stucco, in such a manner as to imitate the colours of painting. MOSCHUS, MUSK, a genus of quadrupeds, of the order pe- cora. The Tibetian musk in size and general appearance re- sembles the small roebuck. It measures about three feet three inches in length, about two feet three inches in height from the top of the shoulders to the bottom of the fore feet, and two feet nine inches from the top of the haunches to the bottom of the hind feet. The upper jaw is considerably longer than the low- er, and is furnished on each side with a curved tusk about two inches long. These tusks are of a different form from those of any other quadruped ; being sharp edged on their inner or lower side, so as to resemble in some degree a pair of small crooked knives: their substance is a kind of ivory, as in the tusks of the baly russa and some other animals. They are hunted for the sake of thcir well-known perfume, which is kept in an small oval receptacle about the size of an egg, hanging from the middle of the abdomen, and pcculiar to the animal. This recep- tacle is found constantly filled with a soft, unctuous, brownish substance, of the most powerful and penetrating smell, and which is no other than the perfume in its natural state. As soon as the animal is killed, the hunters cut off the receptacle or musk bag, and tie it up ready for sale. As musk is an expensive drug, it is frequently adulterated by various substances. As a medicine, it is heid in high estimation in the Eastern coun- tries, and has now becn introduced into pretty general use, especially in those disorders which are commonly termed nerv- ous ; and in convulsive and other cases it is oſten administer- ed in pretty large doses with great success. The Indian musk is rather larger than the common or Tibetian musk, of the co- lour mentioned in the specific character, with the head shaped like that of a horse, upright oblong ears, and slender legs. The pigmy musk is considerably smaller than a domestic cat, mea- suring little more than nine inches from the nose to the tail. MOSQUE, a temple or place of religious worship among the Mahometans. All mosques are square buildings, generally built with stone; before the chief gate there is a square court, paved with white marble, and low galleries round it, whose roof is supported by pillars. In these galleries the Turks wash themselves before they go into the mosque. In each mosque there are a great number of lamps. As it is not lawful to enter the mosque with shoes or stockings on, the pavements are co- yered with pieces of stuff sewed together, each wide enough to hold a row of men kneeling, sitting, or prostrate. The women are not allowed to enter the mosques. About every mosque there are six high towers, called minarets, each of which has three little open galleries one above another: whence, instead of a bell, the people are called to prayer by certain officers appointed for that purpose. Most of the mosques have a kind of hospi- 71. tal belonging to them, in which travellers, of what religion so- ever, are entertained during three days. Each mosque has also a place called tarbe, which is the burying place of its foun- ders; within which is a tomb six or seven feet long, covered with green velvet or satin, at the end of which are two tapers, and round it several seats for those who read the Koran, and pray for the souls of the deceased. MOTACILLA, the Wagtail and Warbler, a genus of birds of the order of passeres, distinguished by a straight weak bill, and very slender legs.-The white wagtail frequents the sides of ponds and small streams, and feeds on insects and worms. The yellow wagtail migrates in the north of England, but in Hampshire continues the whole year. The male is a bird of great beauty; the breast, beily, thighs, and vent-feathers, be- ing of a most vivid and lovcly yellow. The colours of the female are more obscure than those of the male; it wants also those black spots on the throat. Under this genus there are several well known birds, which we shall here describe. The gold crested wren belongs to this class, a native of Europe, and of the correspondent latitudes of Asia and America, is the least of all the European birds, weighing only a single drachm. Its length is about four inches and a half, and the wings when spread out measure little more than six inches. On the top of its head is a beautiful orange-coloured spot, called its crest, which it can hide at pleasure.-The tailor bird, belonging also to this class, is a native of the East Indies. It is remarkable for the art with which it makes its nest, seemingly in order to secure itself and its young in the most perfect manner pos- sible against all dangers from voracious animals. It picks up a dead leaf, and sews it to the side of a living one ; its slender bill is the needle, and its thread is formed of some fine fibles; the lining is composcq of feathers, gossamer, and down.— The nightingale, another of this genus, exceeds in size the hedge sparrow. The bill is brown ; the irides are hazel; the head and back pale tawny, dashed with olive; the tail is of a deep tawny red ; the under parts pale ash colour, growing white towards the vent; the quills are cinereous brown. The male and female are very similar. This bird, the most famed of the feathered tribe, for the variety, length, and sweetness of its notes, is supposed to be migratory. The female builds in some low bush or quickset-hedge well covered with foliage, for such only this bird frequents, and lays four or five eggs of a greenish brown. The nest is composed of dry leaves on the outside, mixed with grass and fibres, lined with hair or down within, though not always alike. The female alone sits on and hatches the eggs, while the male, not far off, regales her with his delightful song; but as soon as the young are hatched, he com- monly leaves off singing, and joins with the female in the task of providing for and feeding them.—The hedge-sparrow, a well- known bird, has the back and wing-coverts of a dusky hue, edged with reddish-brown, rump of a greenish-brown ; throat and breast of a dull ash-colour; the belly a dirty white ; and the legs of a dull flesh-colour. The note of this bird would be thought pleasant, did it not remind us of the approach of win- ter.—The redstart is somewhat less than the redbreast; the forehead is white; the crown of the head, hind part of the neck, and back, are deep blue-gray; the cheeks and throat black; the breast, rump, and sides red; and the belly is white; the two middle tail feathers are brown; the rest red; and the legs are black. The wings are brown in both sexes. The red-breast, universally known, builds not far from the ground, if in a bush ; though sometimes it fixes on an out- house, or retired part of some old building. The nest is com- posed of dried leaves, mixed with hair and moss, and lined with feathers. The eggs are of a dusky white, marked with irregular reddish spots; and are from three to seven in number: insects are their general food; but in defect of these they will eat many other things. No bird is so tame and familiar as this; closely attending the heels of the gardener when he is using his spade, for the sake of worms; and frequently in winter entering houses where windows are open, when they will pick up the crumbs from the table while the family is at dinner. The wheatear is in length five inches and a half. The top of the head, hind part of the neck, and back, are of a bluish gray; and over the eye a streak of white; the under parts of the body yellowish-white; the breast tinged with red; and the legs are S O 694 M O T M O T Diction ARY of MechAN1cAL science. . . black. This bird is met with in most parts of Europe, even as far as Greenland; and specimens have also been received from the East Indies. The young are hatched in the middle of May. In some parts of England these birds are in vast plenty. The wren is a very small species, in length only three inches and three-quarters, though some have measured four inches. It generally carries the tail erect. This minute bird is found throughout Europe; and in England it defies our severest win- ters. Its song is much esteemed, being, though short, a pleas- ing warble, and much louder than could be expected from the size of the bird; it continues throughout the year.—Above an hundred and fifty species, besides varieties, are enumerated by ornithologists as belonging to this genus. MOTE, in Law-books, signifies court, meeting, or conven- tion, as a ward-mote, burg-mote, swain-mote, &c. MOTH, in Zoology, is an insect of the winged kind, which, though insignificant in itself, proves destructive to various crops of garden and field productions. Of these insects there is a great variety, and their natural history is both amusing and instructive. MOTHER of PeARL, is that beautiful natural white enamel, which forms the greater part of the substance of the oyster-shell, particularly of the pearl oyster. Mothek Water, in Chemistry, is the uncrystallizable residue of a compound saline solution : thus the liquor left in a salt pan after the salt is taken out, is the mother-water. .. MOTION, or Local Motion, in Mechanics, is a continued and successive change of place, or it is that affection of matter by which it passes from one point of space to another. Motion is of various kinds, as follows: - - - Absolute Motion, is the absolute change of places in a mov- ing body, independent of any other motion whatever; in which general sense, however, it never falls under our observation. All those motions which we consider as absolute, are in fact only relative; being referred to the earth, which is itself in motion. By absolute motion, therefore, we must only under- stand that which is so with regard to some fixed point upon the earth; this being the sense in which it is delivered by writers on this subject. - Accelerated Motion, is that which is continually receiving constant accessions of velocity. See AcceleRAted Motion. Angular Motion, is the motion of a body as referred to a centre, about which it revolves. - Compound Motion, is that which is produced by two or more powers acting in different directions. See PARALLEloGRAM of Forces. - t Equable Motion, or Uniform Motion, is when the body moves continually with the same velocity, passing over equal spaces in equal times. Natural Motion, is that which is natural to bodies, or that which arises from the action of gravity Relative Motion, is the change of relative place in one or more moving bodies; thus two vessels at sea are in absolute motion (according to the qualified signification of this term) to a spectator standing on shore, but they are only in relative motion with regard to each other. ". Retarded MoTION, is that which suffers continual diminution of velocity, the laws of which are the reverse of those for accelerated motion. See AcceleRATION and RETARDATION. Projectile MoTION, is that which is not matural, but im- pressed by some external cause; as when a ball is projected from a piece of ordnance, &c. See PRojectile. Rectilinear Motion, that which is performed in right lines. Rotatory Motion.—Seaton's Machine for Experiments on Rotatory Motion. This machine is exhibited in the following figure, where the vertical axis N B is turned by the rope M passing over the pulley R, and carrying the scale S. The axis N B carries two equal leaden weights K, D, moveable at pleasure on the horizontal bar H I. The upper part N of the axis is one half the diameter of the part M, so that when the rope is made to wind round N, it acts at half the distance from the axis, at which it acts when coiled round M. When the rope is wound round N, the same ſorce will, produce in the same time but half the velocity which is produced when the rope coils round M, the situation of the leaden weights being the same ; but when the weights K, L, are removed to a double ſº t e º : e $ r e distance from the axis, a quadruple force will be required in order to produce an equal ângular velocity in a given time. | -- – – JD . cº - **- ~~~ºw- | º --- 5 § 62 - N. º . | | lºſ, ; g º º ſº * º •º t Q : M - N S == Laws of Motion, as delivered by Newton in his “Principia,” and on which he has supported the whole system of his philo- sophy, are the three following: 4. - Every body perseveres in its state of rest, or uniform motion in a right line, until a change is effected by the agency of some external force. Any change effected in the quiescence or motion of a body is in the direction of the force impressed, and is proportional to it in quantity. Action and reaction are equal, and in contrary directions. * When speaking of these axioms, or laws of motion, it ought always to be recollected that they are not the efficient opera- tive causes of any thing. A law presupposes an agent; for it is only the mode, according to which an agent proceeds: it implies a power, for it is the order according to which that power acts. Abstracted from this agent, this power, the law does nothing, is nothing; so that a law of nature or of motion can never be assigned as the adequate cause of phenomena, exclusive of power and agency. The Newtonian axioms are, in reality, intermediate propositions between geometry and philosophy; through which mechanics becomes a mathematical branch of physics, and its conclusions possessed of such coherence and consistency among themselves, and with matter of fact, as are rarely to be found in other branches, which ad- mit not of so intimate a union with the science of quantity. The evidences from which our assent to these axioms is derived, are of various kinds:—1. From the constant observa- tion of our senses, which tend to suggest the truth of them in the ordinary motion of bodies, as far as the experience of man- kind extends. 2. From experiments, properly so called. 3. From arguments à posteriori. One or other of these kinds of evidence generally forms a part of our most valuable treatises on mechanics and physics; but there is a fourth way in which the truth of these axioms may be deduced, which is that in which they are shewn to be laws of human thought, intuitive consequences of the relations of those ideas which we have of motion, and of the causes of its production and changes. Motion, in Astronomy, is still farther divided into diurnal, annual, horary, sidereal, &c.; for which see the respective terms. Motion, Spontaneous or Muscular, is that performed by the muscles at the command of the will. - Motion, Natural or Involuntary, that effected without any such command, by the mere mechanism of the parts, such as the motion of the heart, pulse, &c. - Motion, Intestine, the agitation of the particles of which a body consists. - * 4. MoTION, in Music, the manner of beating the measure, to hasten or slacken the time of the words or notes. - * M O U. M O U 695 DICTIONARY OF MECHANICAL SCIENCE, MOTRIX, that which has the power or faculty of moving. MOULD, or MoLD, in the Mechanic arts, &c. a cavity cut with a design to give its form or impression to some softer matter applied therein, of great use in sculpture, foundery, &c. Mould, a thin flexible piece of timber, used by shipwrights as a pattern whereby to form the different curves of the tim- bers, and other compassing pieces in a ship's frame; of these there are two sorts, the bend-mould and the hollow-mould. The former of these determines the convexity of the timbers, and the latter the concavity on the outside, where they approach the keel, particularly towards the extremities of the vessel. The figure given to the timbers by this pattern is called the Bevelling. See that article. - Moulos, in the manufacture of paper, are little frames composed of several brass or iron wires, fastened together by another wire still finer. Each mould is of the bigness of the sheet of paper to be made, and has a rim or ledge of wood to which the wires are fastened; these moulds are more usually called frames or forms. - * - - Moulds for Leaden Bullets, are little iron pincers, each of whose branches terminates in an hemispherical concavity, which when shut forms an entire sphere ; in the lips or sides, where the branches meet, is a little jet or hole through which the melted lead is conveyed. - MoULDs, Glaziers’. The glaziers have two kinds of moulds, both serving to cast their lead. In the one they cast the lead into long rods or canes fit to be drawn through the vice, and the grooves formed therein; this they sometimes call ingot mould. In the other they mould those little pieces of lead a line thick, and two lines broad, fastened to the iron bars; these may be also cast in the vice. - Moulds, among plumbers, are the tables whereon they cast the sheets of lead. These they sometimes call simple tables ; besides which they have other real moulds where with they cast pipes without soldering. MoULDs, used in basket-making, are very simple, consisting ordinarily of a willow or osier, turned or bent into an oval, circle, square, or other figure, according to the baskets, pan- niers, hampers, hats, and other utensils intended.—On these moulds they make, or, more properly, measure all their work, and accordingly they have them of all sizes, shapes, &c. MoULDs, among tallow-chandlers, are of two kinds: the first for the common dipped candles, being the vessel wherein the melted tallow is disposed, and the wick dipped ; this is of wood of a triangular form, and supported on one of its angles, so that it has an opening of near a foot at top: the other, used in the fabric of mould candles, is of brass, pewter, or tin; here each candle has its several moulds. Mould, among gold-beaters, a certain number of leaves of vellum, or pieces of gut cut square, of a certain size, and laid over one another, between which they put the leaves of gold and silver, which they beat on the marble with the hammer. They have four kinds of moulds, two whereof are of vellum, and two of gut; the smallest of those of vellum consists of forty or fifty leaves, the largest contains an hundred; for the others, each contains five hundred leaves. The moulds have all their several cases, consisting of two pieces of parchment, serving to keep the leaves of the mould in their place, and prevent their being disordered in beating. MoULD, in Agriculture, a loose kind of earth every where obvious on the surface of the ground ; called also natural or mother earth ; by some also, loam. * - MOULDINESS, a term applied to bodies which corrupt in the air, from some hidden principle of humidity therein, and whose corruption shews itself by a certain white down, or lanu- go, on their surface, which viewed through a microscope ap- pears like a kind of meadow, out of which arise herbs and flow- ars, some only in the bud, others full blown, and others decayed, each having its root, stalk, and other part. See Mucor. MOULDING, any thing cast in a mould, or that seems to have been so, though in reality it were cut with the chisel or , the axe. r * . MOULDINGS, in Architecture, naked wall, column, wainscot, &c. - MGUNTAIN BLUE. The substance called mountain blue, is one of the native varieties of carbonate of copper, of which projections beyond the there are three, the green, the blue, and the anhydrous. The following is the order of their compositions :— . - 1st. 2d. 3d. Carbonic acid..... ....... .275 ...... 11:00 ...... 257 Deutoxide of copper...... 10:00 ...... 30.00 ...... 10:00 Water..... & & Cº º ºs º e º g e º tº 1° 125 e e º O © tº 2°25 e s e o 's e 0:00 The blue carbonate is found in great perfection at Chessy, near Lyons; also in Bohemia, Saxony, &c. It occurs crystal- lized, in rhomboids, and imperfect octohedra. It also is found in small globular masses, massive and earthy. The earthy variety is called copper azure or mountain blue. The green variety is called malachite, it is found in various forms, but never regularly crystallized, the octohedral variety being a pseudo-crystal derived from the decomposition of the red oxide. This mineral occurs in the greatest beauty in the Uralian mountains of Siberia: it is rarely found in Cornwall. It is of various shades of green, and often cut into small slabs, or used as beads and brooch-stones; the pulverulent variety has been termed chrysocollae and mountain green. There is a very fine blue cupreous preparation called refiner's verditer, principally made by silver refiners. It consists of three pro- portionals of oxid, four of carbonic acid, and two of water. There is a very inferior pigment, also called verditer, which is a mixture of sub-sulphate of copper and chalk. According to Pelletier, a good verditer may be obtained as follows: Add a sufficient quantity of lime to nitrate of copper, to throw down the hydrated oxide; it gives a greenish precipitate, which is to be washed and nearly dried upon a strainer; then incorporate | with it from eight to ten per cent. of fresh lime, which will give it a blue colour, and dry it carefully. Proust obtained a | fine blue carbonate of copper, by adding an alkaline carbonate to a solution of nitrate of copper. The artificial carbonates will probably not answer with every experimentalist. If not, the native mountain blue, may possibly be obtained either under that name or copper azure. - MOUNTAINS. Elevations consisting of clay, sand, or gravel, are called hills; those which consist of stone are called mountains. Mountains are divided into primaeval, that is, of equal date with the formation of the globe, and secondary or alluvial. Among primaeval, those of granite hold the first place. . The highest mountains and most extensive ridges throughout the globe are of that kind. The highest of them never contain metallic ores; but some of the lower con- tain ores of copper and tin. The granite next the ore always abounds in mica. Petrifactions are never found in these prim- aeval mountains. That the formation of these mountains pre- ceded that of vegetables and animals, is inferred from their containing no organic remains, either in the form of petrifaction or impression. Granites were formed by crystallization, an operation that probably took place after the formation of the atmosphere, and the gradual excavation of the bed of the ocean, when the dry land appeared. For by means of the sepa- ration of the aëriform fluids which constitute the atmosphere, the evaporation of part of the water into the atmosphere, and the gradual retreat of the remainder, the various species of earths, before dissolved or diffused through this mighty mass, were disposed to coalesce; and among these the siliceous must have been the first, as it is the least soluble; but as the siliceous earth has an affinity to the other earths with which it was mixed, some of these must have united in various propor- tions, and thus have formed in distinct masses, the feldtspar, schorl, and mica, which compose the granite. Calcareous earth enters sparingly into the composition of this stone; but as it is found in schorl, which is frequently a component part of granite, it follows that it must be one of the primitive earths, and not entirely derived from marine exuviae. Quartz cannot be a product of fire; for in a very low heat it bursts, cracks, and loses its transparency, and in the highest degree of heat that we can produce, it is infusible, so that in every essential point it is different from glass. As granite com- tains earth of every genus, we may conclude that all the simple earths are original. Mountains which consist of limestone or marble of a granular or scaly texture, and not disposed in strata, seem also to have preceded the creation of animals, for no organic traces are found in them. Some of those which con- M (J & M. J & IDICTIONARY OF. MECHANICAL SCIENCE sist of argillaceous stones, and some of the siliceous, contain also no organic remains. ... • * * Alluvial mountains are evidently of posterior formation, as they contain pétrifactions and other vestiges of organic sub- stances; and these are always stratified. Mountains, as to structure, are entire, stratified, and confused. Entire moun- tains are formed of huge masses of stone, without any regular fissures, and are mostly homogeneous. Stratified mountains are those whose mass is regukarly divided by joints or fissures, these are called horizontal, rising, or dipping. Homogeneous stratified mountains consist chiefly of stones of the argillaceous genus, or of the fissile compound species of the siliceous genus, as metallic rock; sometimes of limestone of a granular or scaly texture, in which no animal vestiges appear. This limestone reposes on the argillaceous or siliceous strata; sometimes the argillaceous are covered with masses of granite, sometimes of lawa. These mountains, particularly those of gneiss, metallic rock, and horn-stone, are the chief seat of metallic ores. He- terogeneous, or compound stratified mountains, consist of alternate strata of various species of stones, earths, sands, &c. The limestone here is always of the laminar, and not of the granular or scaly kind, and when it contains any ore, it is placed between its laminae. Coal, bitumen, petrifactions, and organic impressions, are found in these mountains; also salts and calamine. . There are other mountains which cannot be called stratified, as they consist only of three masses; the low- est granite, the middle argillaceous, and the upper limestone. Metallic ores are found in the argillaceous part, or between it and the limestone, Confused mountains consists of stones heaped together without, order, their interstices being filled They scarcely ever contain any Pesides these, these are many mountains in different parts of the world, which derive their origin from volcanoes. The height of mountains is usually calculated by means of the barometer. See BARoMeTER. The highest mountains are those The Himalaya and the Andes are generally allowed to be the highest of these. with clay, sand, and mica. ©re, which are situated at or near the equator. the line of congelation, or of perpetual frost on mountains, is calculated at 15,400 feet, at or near the equator; at the en- trance of the temperate zone, at 13,428 ; at Teneriffe, at 1060; in Auvergne (lat. 45) 6,740; with us (lat. 52), 5,740. On the Andes, vegetation ceases at 14,497 feet; and on the Alps at 9,585. The air is so dry in these elevated situations, that M. d'Arcet observed, that on the Pic de Midi, one of the Pyrenees, salt of tartar remained dry for an hour and a half, though it immediately warmed in the same temperature at the bottom of the mountain. MOUNTING, in Military affairs, signifies going upon duty. Thus, mounting a breach is running up to it; mounting the guard, is going upon guard; and mounting the trenches, is go- ing upon duty in the trenches; but mounting a cannon, mortar, &c. is the setting it on its carriage, or the raising its mouth. MOUSE, a sort of knob, wrought on the outside of a rope by means of spun-yarn, parsling, &c. See the article PUDDEN- ING. It is particularly used on the stays, to prevent it from unhooking when the tackle is slackened. MoUse. See MUs. MOVEABLE, in general, denotes any thing capable of being - moved. The moveable feasts are such as are not regularly held on the same day of the year or month, though they are always on the same day of the week. Thus Easter, on which all the rest depend, is held on the Sunday which falls upon, or next after, the first full moon following the 21st of March. . . MOVEMENT, in Mechanics, a machine that is moved by clock-work. See CLoCK. - Move MENT, in Military affairs. Under this term are compre- hended all the different evolutions, marches, countermarches, and manoeuvres, which are made in tactics for the purpose of retreating from, or of approaching towards, an enemy. It also includes the various dispositions which take place in pitching a camp, or arranging a line of battle. Movement, in Music, the name given to any single strain, or to any part of a composition comprehended under the same : * measure of time. - MUCIC Acid, was called saclactic acid from its having been found in the sugar of milk; but as oxalic acid is also found in milk, and this acid is found in all gums, it has been better distinguished by the name of mucic. It forms, with the oxides of metals, salts which are scarcely soluble. - MUCILAGE, a glutinous matter obtained from vegetables, transparent and tasteless, soluble in water, but not in spirits of wine. It chiefly consists of carbon, hydrogen, and a small quantity of oxygen. See GLUTEN. ' MUCOR, in Botany, a genus of the order fungi, in the cryp- togamia class of plants. There are seventeen British species. The lichnoides, or little, black, pin-beaded mucor, grows in groups near to each other, in chasms of the barks of old trees, and upon old park-pales. The common gray mould, grows on bread, fruit, plants, and other substances in a putrid state. It grows in clusters; the stalks a quarter of an inch high, pellu- cid, hollow, and cylindrical, supporting each in a single globu- lar head, at first transparent, afterwards dark-gray; which bursts with elastic ſorce, and ejects small round seeds disco- verable by the microscope. The yellow frothy mucor, is found on the leaves of plants, such as ivy, beech, &c. sometimes upon dry Sticks, and frequently upon the tan or bark in hot-houses. Jt is of no certain size or figure, but of a fine yellow colour, and a substance at first resembling cream beaten up into froth. In the space of 24 hours it acquires a thin filmy coat, becomes dry, and full of sooty powder adhering to downy threads. MUCUS, a fluid secreted by certain glands, and serving to lubricate many of the internal cavities of the body. In its natural state it is generally limpid and colourless; but from certain causes will often assume a thick consistence, and whit- ish colour, like pus; but strong sulphuric acid and water, dilu- ted Sulphuric acid, and caustic alkaline, lixivium, and water, will serve to distingush pus from mucus ; the vitriolic acid se- parates it from coagulable lymph, and alkaline lixivium from serum. Thus when a person expectorates matter, the decom- position of which he wishes to ascertain, let him dissolve it in vitriolic acid, and in caustic alkaline lixivium; and let him add pure water to both solutions. If there is a fair precipitation in each, he may be assured that some pus is present. But if there is a precipitation in neither, it is a certain test that the mixture is entirely mucus. If the matter cannot be made to dissolve in alkaline lixivium by time and trituration, we have also reason to believe that it is pus. - Mucus, NASAL, a name given to a liquid secreted in the cavities of the nose, and discharged outwardly, either by the nostrils or by the fauces when it descends by the posterior part of the nasal cavities, in which it is thrown out by spitting. This liquid, always exposed to the air, which continually passes through the nostrils, is thicker, more viscid, and more adhesive than the tears; and the carbonate of soda it con- tains, whilst the latter contains only soda, announces that the air deposits in it a part of the carbonic acid which it contains, especially as it is expired out of the lungs. When it becomes thick in the air, it frequently assumes in it the form of small, dry, brilliant, and as it were micaceous plates. The nasal mucus experiences no real putrifaction in the air. Water does not dissolve it. Acids thicken it when they are concentrated and employed in small proportions; but when we add a larger quantity, they re-dissolve, and give it different shades of colour. The mucus of the nostrils maintains the softness of the merg- branaceous sides of the nasal cavities. It moderates the too great sensibility of the nervous papillae, stops and fixes the odorous bodies, and blunts their too great activity. It like- wise purifies the air that is respired, by taking from it the pul- verulent particles which it carries along with it, and which would be more hurtful in the lungs. - MUFFLE, in metallurgy, an arched cover, resisting the strongest fire, and made to be placed over coppels and tests in the operations of assaying, to preserve them from the falling of | coals and ashes into them ; though, at the same time, of such a form, as is no hinderance to the action of the air and fire on the metal, nor to the inspection of the assayer. * To MUFFle the Oars, is to put some matting, &c. round that part of the oar which lies on the edge or gunnel of the boat, when rowing, to prevent its making a noise against the | thoſes. MUFTI, or MUPhti, the chief of the ecclesiastical order, or primate, of the Mussulman religion. His authority is very great. M U L M Uj I, 697 DECTIONARY OF MECHANICAE, SELENCE. In all actions, especially criminal ones, his opinion is required by giving him a writing, in which the case is stated under feign- ed names, which he subscribes with words, He shall or shall not be punished. . Such outward honour is paid to the mufti, that || the grand seignior himself rises up to him, and advances seven steps to meet him, when he comes into his presence. The elec- tion of the mufti is solely in the grand seignior. ... MUGIL, Mullet, a genus of fishes of the order abdominales. Gmelin notices only five species. Shaw mentions nine. The common mullet is generally about 14 inches in length, and is found not only in the Northern and Mediterranean seas, but in the Indian and Western oceans. The mullets collect in multi- tudes almost close to the shores, thrusting their head into the soft muddy bottoms in quest of aquatic insects. On the ap- proach of summer they ascend rivers to a considerable distance from the sea, to deposit their ova. They are regarded by many as excellent food, but are not often, seen at the tables of the opulent. MULBERRY. See MoRus. MULE, in zoology, a mongrel kind of quadruped, generated between an ass and a mare, and sometimes between a horse and a she-ass. The mule is a monster of a middle nature be- tween its parents, and incapable of propagating its species, Mules are chiefly used in countries where there are rocky and stony roads, as about the Alps, Pyrenees, &c. No creatures are so proper for carrying large burdens, and none so sure footed. They will travel several months together with six or eight hundred weight upon their backs; they are much hardier and stronger than the horse, and will live and work twice his age. - "ºutes, among gardeners, denote a sort of vegetable mon- sters produced by putting the farina fecundans of one species of plant into the pistil or utricle of another. . The signification of the word is likewise extended to every kind of animal pro- duced by a mixture of two different species. MULLERS Fort GRINDING COLOURS, according to the com- mon construction, are too well known and too simple to meed a particular description here. But Rawlinson's concave muller, for which the Society of Arts presented him a silver medal and ten guineas, on account of its ingenuity, shall find a place here.—This machine has been used for several years, and has been found much more effectual and expeditious in reducing the colour to extreme fineness than the usual method, and much less injurious to the health of the workman, who fre- quently has done as much with it in three hours as he could in twelve with the muller and slab. The machine consists of a flat cylinder of black marble, sixteen inches and a half diame- ter, and four and a half thickness, with an axle traversing its centre, (thus somewhat resembling a common cutler's grind- stone.) It is suspended on a similar frame, in a vertical posi- tion, and turned round in the same manner by a winch: a con- cave piece of marble is provided, of the same breadth as the circular stone, forming a segment of the same circle one-third of the circumſerence in extent: this, which may be considered as the mauller, is fitted into a piece of solid wood of similar shape, one end of which is secured loosely by a hinge or other- wise to the frame; the other end, rising over the circular stone, and supported by it, is further pressed down on it by a long spring bent over from the opposite extremity of the stand, and regulated as to its pressure by a screw, whose end turns against the concave muller: a slight frame of iron in front, moveable on a hinge, by which it is secured to the frame, supports a scraper, for taking off the colour, formed of a piece of watch- spring, which is turned back out of the way when not in use. Mr. R. thinks the circular grindstones might be made much larger, than he used, to advantage, and that one of two feet diameter would not occasion too much labour to one man to turn it: he computes that in his machine there are seventy square inches of surface of the concave muller in constant work on the paint, while in the common muller not more than sixteen Square inches are usually in contact with the slab. The ma- chine will be found equally serviceable for the colours ground in water, as for those prepared with oil, according to Mr. R., who highly recommends, its use to all colourmen. Mr. R. advises, in making up the colours in bladders, to insert a bit of quill; reed in the neck of the bladder, which will thus bind better in tying; and, admitting of a secure stopper, will be more cleanly and less wasteful than the usual method of stop- ping with a nail, and keep the colour more safe from the air. MULLUS, SURMULlet, a genus of fishes of the order thora- cici. Gmelin reckons six, Shaw thirteen species. The red | Surmullet is principally found in the Mediterranean and North seas, where it arrives at the length of twelve or fifteen inches; its colour is a rose red, tinged with olive-colour on the back, and of a silvery cast towards the abdomen. It is generally considered as a very delicate fish, and is celebrated for having been the fashionable object of Roman luxury, and for which enormous sums are reported to have been sometimes given. The Romans practised a singular refinement in luxury, by first bringing the fish alive to the table, in a transparent vessel, in order that the guests might contemplate the beautiful and rapid changes of its evanescent colours during the time of its gradual expiration; after which,it was prepared for their repast. Mºntangular, a figure, or body, which has many angles. * MULTILATERAI, in Geometry, is applied to figures which have more than four sides or angles. MULTINOMIAL, or MULTINoMIAL Roots, in Mathematics, Such roots as are composed of many names, parts, or mem- bers ; as, a + b + d -- c, &c. See Root. MULTIPLE, in Arithmetic, is a number which contains another number a certain number of times; thus 18 is a multi- ple of 6, or of 3, or of 9, &c. Common MULTIPLE of two or more numbers, is that which contains those numbers a certain number of times; thus 36 is a common multiple of 4 and 9, being equal to 9 times the first, and 4 times the second. To find the least common Multiple of several Numbers.—Reduce them all to their prime factors, then the product of the greatest powers of those prime factors is the least common multiple required. Let it be proposed to find the least common mul- tiple of 12, 25, and 35, or the least number that will divide by each of them without a remainder. º Here 12 = 3 x 22; 25 = 5?, and 35 = 5 × 7; therefore 3 × 22 x 5” x 7 - 210, the least common multi- ple required. MULTIPLE RATIo, or Proportion, is that which is between multiples. If the less term of the ratio is an aliquot part of the greater, the ratio, or the greater to the less, is balled the multiple, and that of the less to the greater, submultiple. . A submultiple number is that contained in the multiple ; thus, the numbers 1, 2, and 3, are submultiples of 9. Duple, triple, &c. ratios, as also sub-duples, sub-triples, &c. are so many species of multiple and submultiple ratios. MULTIPLICAND, in Arithmetic, is one of the factors in multiplication, being that which is multiplied by the other, which is called the multiplier. MULTIPLICATION, is one of the principal rules in arith- metic and algebra; and consists in finding the amount of a given number or quantity, called the multiplicand, when repeated a certain number of times expressed by the multiplier; and this amount is generally termed the product; also the multiplier and multiplicand are commonly called factors. Multiplication is either simple or compound. Simple MULTIPLICATION, is when the proposed quantities are integral numbers.-Rule. Place the multiplier under the multi- plicand, so that units may fall under units, tens under tens, and so on. Then begin at the right hand, and multiply every figure in the multiplicand, by each of the figures in the multi- plier. Find how many tens there are in the product of every two simple figures, and set down the remainder directly under the figure you are multiplying by, or, if there be nothing over, a cipher. Carry as many units as there were tens to the pro- duct of the next figure, and proceed in like manner till the whole is finished. Then add all the separate products together for the answer. Proof of MULTIPLICATION. 1. Invert the operation, by making the multiplier and multiplicand change places, and if you thus obtain the same result, it is highly probable the work is right. 2, Cast out all the 9's from the multiplier, multipli- cand, and product; and multiply the overplus of the two former together, and cast the 9's out of this product: then if 8 P 698 M U N M U. R. pictionARY of MechANICAL science. * this remainder be the same as that arising from the total pro- duct, the operation is probably right; but if not, it is certainly wrong. This proof depends upon a singular property of the number 9; viz. that any number divided by 9, will leave the same remainder, as the sum of its digits when divided by the same number. 3. Another proof for multiplication is drawn from a particular property of the number 11, which is this, that the sum of the digits in the odd places, that is, the 1st, 3d, 5th, &c. being taken from the sum of the digits in the 2d, 4th, &c. places, the remainder, when divided by 11, will leave the same overplus, as the whole number when divided by 11. If the former sum be greater than the latter, as many times 11 unust be added to it, as will make the latter sum the greater of the two. This being observed, the proof by this number will be the same as in the former case. O • 3% proof by 9. Example. 4. 33 proof by 11. 45684 multiplicand. 4374 multiplier. But it must be evident that this process is at variance with all the known laws of mathematical science, since it supposes a knowledge of division even previous to that of multiplication, which is absurd; and the editor very reluctantly admits into the pages of his work an illustration which is opposed to prae- tice, but sanctioned by the authority of a custom known only among the unscientific and illiterate. º The other proof by inverting the operation depends upon this; that the product of two numbers is the same, whichever of the two is the multiplier; or generally, that a times b is the same as b times a ; which, though generally considered as an axiom, is in fact a proposition, and one that is not very easily demonstrated. - Compound MultiplicAtion, is the method of finding the pro- duct arising from a compound and simple quantity.—Rule. Place the multiplier under the lowest denomination of the multiplicand, and multiply this denomination by the multiplier. Find how many units of the next higher denomination are contained in the product; set down the remainder, and carry the units to the next product, with which proceed as before, and so on through all the denominations to the last, and the result will be the answer required. Note. If the multiplier exceed 12, the operation will be much simplified as follows:–1. If the given multiplier be a compo- site number, multiply successively by each of its factors, instead of the whole number at once. 2. If the given multi- plier be not a composite number, take that which is nearest to it, and multiply by its factors as before ; then add or subtract as many times the first line, as the number so taken is less or greater than the multiplier. Also, if there be any fractional part belonging to the multiplier, take such part of the multiplicand as this fraction is of a unit, and add it to the result before found. MULTIPLIER, or MULTIPLICATor, the number by which another is multiplied. MULTIPLYING GLASS, in Optics, one wherein objects ap- pear increased in number. It is otherwise called a polyhedron, being ground into several planes that make angles with each other; through which the rays of light issuing from the same point undergo different refractions, so as to enter the eye from every surface in a different direction. MULTIVALVES, in Natural History, the name of a general class of shell-fish consisting of three or more shells. MUM, a kind of malt liquor much drunk in Germany, and chiefly brought from Brunswick, which is the place of most note for making it. MUMMY, a body embalmed or dried, in the manner used by the ancient Egyptians: or the composition with which it is embalmed. Mummy has been esteemed resolvent and bal- Samic ; but whatever virtues have been attributed to it, seem to be such as depend more upon the ingredients used in preparing the flesh than in the flesh itself. MUNICIPAL, in the Roman civil law, an epithet which sig- nifies invested with the rights and privileges of Roman citizens. MUNICIPAL, in Great Britain, is applied to the laws that ob- tain in any particular city or province ; and those are called 2098.21816 municipal officers who are elected to defend the interest of cities, to maintain their rights and privileges, and to preserve order among the citizens. - > MURAL ARCH, (from murus, a wall,) a wall, or arched wall, placed exactly in the plane of the meridian, for fixing a large quadrant, sextant, or other instrument, to observe the meri- dian altitude, &c. of the heavenly bodies. - MURAENA, the Eel, a genus of fishes of the order apodes. There are five species, according to Shaw. Gmelin enumerates nihe. The common eel is particularly distinguished by the steadiness and uniformity of its colours; an olive-brown on the back, and silvery lustre on the sides and beneath; but more expressively still by the great elongation of its under jaw. Its general size is from two to three feet; it is slow in its growth, and considered as very long lived. Its usual food consists of insects, worms, and the eggs of other fishes. It is viviparous, | producing great numbers at a birth; but of a very diminutive # size. It continues generally during the day in its hole in the banks, which it furnishes with two avenues, to facilitate its es- cape and security. By night it ranges for food. In winter it appears to be ingulfed in mud, and remains in this state of seclusion and tranquility, if not torpor, till the return of spring invites it to a renewal of its excursions. The conger eel, gene- rally darker above, and more splendid beneath than the former species, grows to its largest size in the Mediterranean, where it is sometimes found ten feet long, and a hundred pounds weight. It is found in the North American seas also : it occa- Sionally, particularly in the spring, makes excursions into riv- ers, and is found in vast abundance in the Severn. Congers are extremely voracious, devouring immense quantities of the smaller fishes, and of crabs before the shell of the latter is completely formed and hardened. MURDER. See HoMICIDE. MUREX, in Natural History, a genus of univalve or simple shells, without any hinge, formed of a single piece, and beset with tubercles or spines. The mouth is large and oblong, and has an expanded lip, and the clavicle is rough. - MUREX, in Zoology, a genus of insects belonging to the order of vermes testacea. From a species of murex on the coasts of Guayaquil and Guatimala, in Peru, a liquor is ex- tracted which dyes cottons, silks, and wool of a beautiful per- manent purple colour. The shell which contains it adheres to the rocks that are washed by the sea. It is of the size of a large walnut. The liquor may be extracted two ways; some kill the animal after they have drawn it out of the shell, then press it with a knife from head to tail, separate from the body the part where the liquor is collected, and throw away the .# When this operation, after being repeated on several snails, has af- forded a certain quantity of fluid, the thread intended to be dyed is dipped in it, and the process is finished. The colour, which is at first of the whiteness of milk, becomes afterwards green, and is not purple till the thread is dry. Those who disapprove of this method draw the fish partly out of the shell, and; squeezing it, make it yield a fluid which serves for dyeing : they repeat this operation four times at different intervals, but always with less success. If they continue it, the fish dies. No colour at present known, says the Abbe Raynal, can be compared to this, either as to lustre, liveliness, or duration. It succeeds better on cotton than wool, linen, or silk. MURIATES, in Chemistry, a genus of salts formed from the muriatic acid with certain bases. MURIATIC Acid. When equal volumes of hydrogen and chlorine gases are mixed and exposed to light, they combine and produce a sour compound commonly called muriatic acid gas, or, in conformity to the modern momenclature, hydro- chloric acid gas. Muriatic acid may also readily be procured by acting upon common salt by sulphuric acid; the evolved gas must be received over mercury. It was first obtained pure by Dr. Priestley, but its composition was discovered by -Scheele, and has since been most ably investigated by Sir Humphrey Davy. Muriatic acid gas extinguishes flame: it is greedily absorbed by water, which takes up 480 times its bulk, and has its specific gravity increased from 1 to 1-210. Thus, dissolved in water, it forms the liquid muriatic acid, or spirit of salt, and may easily be procured by distilling a mixture of dilute sulphuric acid and common salt, as directed in the Lon- M U S M U S 699 DICTIONARY OF MECHANICAL scIENCE. ar don Pharmacopoeia. The marine acid in commerce has a straw colour; but this is owing to accidental impurity; for it does not obtain in the acid produced by the impregnation of water with the aëriform acid. The muriatic acid is one of those longest known, and some of its compounds are among those salts with which we are most familiar. The muriates, when in a state of dryness, are actually chlorides, consisting of chlo- rine and the metal; but moisture makes them instantly pass to the state of muriates. º • * MURRAIN, or GARG Le, a contagious disease among cattle, principally caused by a hot dry season, or general putrefaction of the air, which begets an inflammation of the blood, and a swelling in the throat, that soon proves mortal. The symptoms are, a hanging down and swelling of the head, abundance of gum in the eyes, rattling in the throat, a short breath, palpitation of the heart, staggering, a hot breath, and a shining tongue. MUS, the Rat, a genus of mammalia, of the order glires. There are forty-six species. The musk rat, as large as a small rabbit, and very common in Canada, resembles the beaver in the shape of its body, and in its instincts and character. It lives in society, and constructs its habitation with great skill and art, about two feet in diameter, and stuccoed within with particular neatness, on the border of some lake or stream. On the outside it is covered with a matting of rushes, compacted with great closeness to preclude moisture. These animals live on roots and herbage, which, however, they do not store up in their houses, but make excursions for, as they are wanted dur- ing the winter; in summer they make long progresses in pairs. They have a strong odour of musk, and walk and run with great awkwardness; are easily tamed, and highly valued for their fur. The Norway rat, supposed to have been imported into Europe from India, has in this country almost extirpated the black rats. It subsists, not only on grain and fruits, but frequently attacks poultry and rabbits, as well as various other animals. The black rat, is considerably smaller than the for- mer; its habits are almost precisely similar. It is supposed to come from the same countries. It is reported by travellers, that in various parts of Germany it is sometimes taken and domesticated, and, having a bell put round its neck, is thus almost invariably found to alarm all others of its species from the vicinity. The water rat, inhabits the temperate and cold climates of Europe and Asia, frequenting the banks of rivers in which it burrows. It subsists on frogs, on roots and other vegetable substances; swims with great speed, and can re- main under water a considerable time. It never infests houses. The hamster, is a species of the pouched rats, and the sole JEuropean species of that description. The pouches are one on each side of the mouth, and, when filled, are like two blown bladders. These animals are found in Poland and Russia, and are extremely injurious by the quantities of grain which they devour, and carry off for their autumnal store in their pouches. The females arrange their mansions differently from the males, and never reside with them. As winter approaches, they seclude themselves completely, and enjoy their stores, which are generally consumed when the winter reigns in full rigour: they roll themselves up, and continue till spring in a state of profound slumber. Their bodies are cold, the fat coagulated, and their limbs stiffened, and they may be opened without awaking them. The heart beats only fifteen times in a minute, while in the summer its pulsations are 150 in the same time. The waking of the hamsters from their lengthened sleep is gradual, occupying sometimes no less than two hours. These animals are unsocial, fierce, and malignant. They attack every Weaker creature, and very frequently destroy each other. The common mouse, inhabits almost every part of the world, is shy and timid, but not ferocious. It produces generally from six to ten at a birth, and breeds several times in a year. Its skin is sleek, and its eyes are bright and lively; its limbs are neatly formed, and its movements are extremely agile. The long- tailed field-mouse, is somewhat larger than the former, and of a yellowish-brown colour. It feeds on acorns, fruits, and grain, and lays up magazines in its burrow for the winter. It is found principally in dry grounds, is common in all the temperate regions of Europe, and is particularly abundant and destruc- tive in France, where it is stated to commit very great waste. Under a scarcity of the usual supplies, these animals are sup- posed to destroy each other. The harvest mouse, is the smallest of British quadrupeds, weighing only the sixth part of an ounce, Its nest is most artificially platted of the blades of wheat, and of the size of a cricket ball, the opening to it being closed up so skilfully, as to be almost imperceptible. Such is its com- pactness, that it may be rolled over the table without derange- ment. One found of this description contained eight young, and appeared completely full without the dam. In the winter these animals burrow deep in the earth; but their favourite habitation is the corn-stack. The blind rat, is perhaps one of the largest and most remarkable of its tribe, measuring between seven and eight inches in length, and being entirely destitute both of eyes and tail. - - MUSA, in Botany, a genus of the polygamia monoecia class and order. Natural order of scitamineae. There are three species: M. paradisiaca, plantain-tree, rises with a soft herba- ceous stalk, fifteen or twenty feet in height; the lower part of the stock is frequently as large as a man's thigh, diminishing gradually to the top, where the leaves come out on every side, being often more than six feet long and two broad. . When the plant is grown to its full height, the spike of ſlowers appears from the centre of the leaves nearly four feet in length, nodding on one side. The fruit is about nine inches long, and more than an inch in diameter, a little incurved, having three angles; the skin is tough, within is a soft pulp of a luscious sweet flavour; the spikes of the fruit are often so large as to weigh upwards of forty pounds. It is a native of the East Indies and other parts of the Asiatic continent; it is generally cultivated between the tropics, the fruit being excellent nutritious food. The banana-tree, differs from the preceding in having its stalks marked with dark purple stripes and spots: the fruit is shorter and rounder, with a soft pulp of a more ſuscious taste. See BANANA. … MUSCA, in Natural History, the Fly, a genus of insects of the order diptera. This is a very numerous genus, not fewer than a thousand species having been enumerated. . They are divided into sections; viz., A. with short feelers; and B. with- out feelers. These sections are again separated into others. The larva in the different tribes of flies differ far more in habit than the complete insects, some being terrestrial, and others aquatic. Those of the common kinds are distinguished by the title of maggots, and spring from eggs deposited on various putrid substances. Several of the aquatic kinds are of singu- larly curious formation, and exhibit wonderful examples of the provision ordained by nature for the preservation of even the meanest animals. The general form of the pupa is that of an oval, differently modified, according to the species, and formed by the external skin of the larva. Some species cast their skin before they change into the pupa state. MuscA AUSTRALI's, the Southern Fly, or Bee, is situated south of the Cross, and by the Antarctic circle; it contains four stars of the fourth magnitude. The introduction of the Bee among the celestial host is a pretty idea, as well on account of the natural qualities of this most extraordinary insect, as on account of its being the old hieroglyphic of royalty. Of the insentient part of animated nature, the bee is prince and chief for foresight, ingenuity, industry, and fidelity: it was thence the fittest symbol of a good king. - MuscA BoreAlis, the Northern Fly, is a small and modern asterism, containing only six stars, viz. one of the third magnitude, two of the fourth, &c. It is situated north of Aries, and south of Triangula and Perseus. MUSCHENBROEK, Peter, a very eminent mathematician and philosopher, was born at Utrecht, about the year 1700. He was professor of mathematics, first in that city, and after- wards at Leyden, where he died in 1761. MUSCI, in Botany, Mosses, one of the seven families into which Linnaeus divided all vegetables. These plants constitute the second order of the class cryptogamia. This order is sub- divided into eleven genera, from the presence or absence of the calyx, which in these plants is a veil that is placed over the tops of the stamina, and denominated calyptra, from the sexes of the plants, which bear male and female flowers, some- times on the same, sometimes on distinct roots, and from the manner of growth of the female flowers, which are sometimes produced singly, sometimes in bunches or cones. 700 M U Š M U S DictionARY OF MECHANICAL SCIENCE, Musci, is also the name of the fifty-sixth order in Linnaeus's Fragments of a Natural Method, eonsisting of genera which are exactly those of the second order in the class cryptogamia, These plants resemble the pines and firs, and other evergreens in that class, in the form and disposition of their leaves, and manner and growth of the female flowers, which are generally formed into a cone. They frequently creep, and extend them- selves like a carpet upon the ground, trees, and stones, col: lected into bunches or tufts. Few of the mosses are annual plants, being mostly perennial and evergreens. Their growth is slow; though preserved dry several years, they resume their original verdure upon being moistened. They delight in a cool moist situation, and northerly exposure, where they are screened from the sun. The roots are fibrous, slender, branched, and short. The stems and branches are cylindric and weak, creeping on the ground, and striking root on every side. , MUSCICAPA, the Fly-catcher, a genus of birds of the order asseres. There are seventy-nine species. The spotted fly- batcher arrives in this country in the spring, and leaves it in September. It attaches its nest not unfrequently to the end of a beam of a house; and sometimes builds it in a vine or sweet- briar tree, spread against a wall. It returns for a succession of seasons to the same situation. It feeds on insects, which it catches with astonishing dexterity, sometimes on the Wing, sometimes by a sudden leap from its perch. It is one of the most silent and most familiar of summer birds. Its only note is a plaintive sound on the approach of danger. In Kent it is called the cherry-sucker, being particularly fond of that fruit. The pied fly-catcher, is not to be found in great numbers in any part of this island, but is most frequently to be met with in Yorkshire, and the contiguous counties. MUSCLE, in Anatomy, a part of the human body, destined to move some other part, in general by a voluntary motion, being composed principally of flesh and tendinous fibres, with veins, nerves, and lymphatics; surrounded by, or enclosed in, one common membrane. The muscular parts of animals are known in common language by the name of flesh. Muscular flesh is composed of a great number of fibres and threads, of reddish or whitish colour; these, after they have been acted on by water, to separate the extraneous matter, are left in the state of gray fibres, insoluble in water, and becoming brittle when dry. The muscles likewise contain albumen, gelatine, extractive, phosphate of soda, of ammonia, and lime. MUSCLES, Insertion and Force of the. The all-wise Author of nature has furnished animals with limbs moveable about the joints by means of muscular cords inserted near the joint, or centre of motion. In order to calculate the force of any mus- cle, we are to consider the bones as levers; and then the power or force of the muscle will be always to the resistance or weight it is capable of raising, as the greater distance of the weight from the centre of motion is to the lesser distance of the power. The muscles that move the lower jaw, when taken altogether, do not in a man exceed the weight of one pound, and yet exert a force equal to 534 pounds, and in mastiff-dogs, wolves, bears, lions, &c. their force is vastly superior. The motion of the far greater part of the muscles are voluntary, or dependent on our will; those of a few others involuntary. The former are called animal, the other natural motions. Finally, the motions of some of the muscles are of a mixed kind, partly animal and partly natural. Those muscles which perform the voluntary motions, receive nerves from the brain or spinal marrow ; those which perform their motions involuntarily, have their nerves from the cerebellum; and those whose motion is partly volun- tary, and partly involuntary, have theirs in part from the brain, and in part from the cerebellum. MUSES, certain fabulous divinities amongst the Pagans, supposed to preside over the arts and sciences. Some reckon the muses to be no more than three, viz., Mneme, Aoede, and Melete; that is, Memory, Singing, and Meditation: but the most ancient authors, and particularly Homer and Hesiod, reckon nine; viz., Clio, which means glory; Euterpe, pleas- ing; Thalia, flourishing; Melpomene, attracting; Terpsichore, rejoicing the heart; Erato, the amiable; Polyhymnia, a multi- tude of songs; Urania, the heavenly; and Calliope, sweetness of voice. To Clio they attributed the invention of history; to of the flute; to Terpsichore, the harp; and to Erato, the lyre and lute; to Calliope, heroic verse; to Urania, astrology; and to Polyhymnia, rhetoric. - 3 MUSEUM, a collection of rare and interesting objects, selected from the whole circle of natural history and the arts, and deposited in apartments or buildings, either by the com- mendable generosity of rich individuals, generally governments or monarchs, for the inspection of the learned and the great mass of the public. The term, which means literally, a study, or place of retirement, is said to have been applied originally to that part of the royal palace at Alexandria appropriated for the use of learned men, and the reception of the literary works then extant. According to ancient writers, they were formed into classes or colleges, each of which had a competent sum assigned for their support; and we are further informed, that the establishment was founded by Ptolemy Philadelphus, who added a most extensive library. MUSHROOM. Agaricus Campestris.--Is cultivated and well known at our tables for its fine taste and utility in sauces. These plants do not produce seeds that can be saved; they are therefore cultivated by collecting the spawn, which is found in old hot-beds and in meadow lands. Various methods have been lately devised for raising mushrooms artificially : but none seem to be equal to those raised in beds, as is de- scribed in all our books of gardening. Raising this vegetable in close rooms by fire heat, has been found to produce them with a bad flavour; and they are not considered so wholesome as those grown in the open air, or when that element is ad- mitted at times freely to the beds. MUs H.Room, Brown. Agaricus Cinnamomeus.—The whole of this plant has a nice smeli, and when stewed or broiled has a pleasant flavour. It is to be found in dry woods, old pastures, &c. and is fit for use in October. * MUSH Room, Violet. Agaricus Violacews.—This mushroom requires more broiling than all the rest; but when done well and seasoned, it is very good. It is found in dry woods, old pastures, &c. where it grows to a large size. MUSIC, a science, which teaches the properties, depen- dencies, and relations of melodious sounds; or the art of pro- ducing harmony and melody by the due combination and arrangement of those sounds. The ancient writers on this science differ greatly as to its object and extent. In general they give to it a much wider latitude than that which it obtains with us. Under the name of music they comprehended not only the melodious union of voices and instruments, but also the dance, gesture, poetry, and even all the other sciences. Hermes defines music to be the general knowledge of order; which was also the doctrine of Plato, who taught that every thing in the universe was music. Music, however, properly so called, only concerns the due order and proportion of sounds; and is divided into two parts, the theoretical and the practical. Theoretical music comprehends the knowledge of harmony and modulation ; and the laws of that successive arrangement of sound by which air or melody is produced. Practical music is the art of bringing this knowledge and those laws into ope- ration, by actually disposing of the sounds, both in combina- tion and succession, so as to produce the desired effect; and this is the art of composition: but practical music may in fact be said to extend still further, and to include not only the pro- duction of melodious and harmonious composition, but also its performance. - MUSICAL or HARMon1AL PROPORTION. See PROPORTHoN. MUSK, a substance secreted into a bag, situated in the um- bilical region of the moschus moschifer. Its colour is brownish red; its feel unctuous; its taste bitter; and its smell aromatic and intensely strong. It is partially soluble in water, which acquires its smell; and in alcohol, but that liquid does not retain the odour of musk. MUSKET, a fire-arm, borne on the shoulder, and used in war. The length of a musket is fixed at three feet eight inches from the muzzle to the pan. In Fortification, the length of the line of defence is limited by the ordinary distance of a musket- shot, which is about one hundred and twenty fathoms. MUSKETOON, a short thick musket, whose bore is the thirty-eighth part of its length: it carries five ounces of iron, Melpomene, tragedy; to Thalia, comedy; to Euterpe, the use l or seven and a half of lead, with an equal quantity of powder. , M U T M Y R 701 DICTIONARY OF MECHANICAL SCIENCE. MUSLIN, a fine thin sort of cottom cloth, which bears a downy map on its surface. See Cotton. MUSTARD, White. Sinapis Alba.-This is sown early in the spring, to be eaten as salad with cress and other things of the like nature; it is of easy culture. A salad of this kind may be readily, raised on a piece of thick woollen cloth, if the seeds are strewed thereon and kept damp; a convenient mode practised at sea on long voyages. Cress and rape may be raised in the same manner. - MUSTELA, a genus of quadrupeds of the order ferae. There are twenty-eight species. M. lutra, the common otter, found in almost every part of Europe, as well as in the colder regions of Asia; inhabiting the banks of rivers, and feeding principally on fish. The length of the otter is nearly two feet from nose to tail, and of the tail about 16 inches. Its colour is a deep brown, with a small light-coloured patch on each side of the nose, and another under the chin. The otter shews great sagacity in forming its habitation; it burrows under ground on the bank of some river or lake, and always makes the entrance of its hole under water, working upwards to the surface of the earth ; and, before it reaches the top, makes several holts or lodges, that in case of high ſloods it may have a retreat, and then makes a minute orifice for the admission of air. The otter is naturally a very fierce animal, and will inflict very severe wounds on its antagonists. The female produces four or five young at a birth; this commonly happens early in the spring. Young otters, if taken at a very early age, may be tamed and taught to hunt for fish, and bring them to their mas- ter. The smaller otter, very much resembles the common otter, but is smaller: the body is of a dusky colour, but with a consi- derable cast of tawny. In size it falls short of the common otter, measuring about a foot in length. Its fur is very valu- able, and next in beauty to that of the sable. The sea otter, is the largest of the otters, measuring about three feet from the nose to the tail, and the tail thirteen inches. The colour of this species is a deep glossy brownish black, the fur being extremely soft and very fine. Great numbers are found in Behring's islands, the Kamschatka, the Aleutian, Fox, and }{urile islands. The ferret, has eyes red and fiery. It inhabits Africa. In Europe it is tamed to catch rabbits, rats, &c. It procreates twice a year, and brings forth from six to eight at a time. The stoat, is about ten inches long, hair short, which in morthern climates becomes white, except the outer half of the -tail, which remains black. The fur is very valuable. MUSTER, in a military sense, a review of troops under arms, to see if they be complete, and in good order; to take an account of their numbers, the condition they are in, viewing their arms and accoutrements, &c. Muster Roll, a specific list of the officers and men in every regiment, troop, or company, which is delivered to the inspect- ing field-officer, muster-master, regimental or district pay- master (as the case may be) whereby they are paid, and their condition is known. - g MUSTERING, the act of calling over a list of the whole ship's company, or any particular detachment thereof, who are accordingly to answer to their names. MUTE, a person refusing to plead to an indictment for felony, &c. is considered as pleading guilty, and punished as upon confession. A prisoner deaf and dumb from his birth may be arraigned for a capital offence, if intelligence can be conveyed to him by signs or symbols. Mute, in Grammar, a letter which yields no sound without the addition of a vowel. ... • MUTILLA, genus of insects of the order hymenoptera. MUTINEER, one who mutinies. MUTINY, in a military sense, to mutiny is to rise against authority. Any officer or soldier who shall use traitorous or disrespectful words against the king, or any of the royal family; or who shall behave himself with contempt or disrepect towards the general, or other commander-in-chief of the forces, or shall speak words tending to their hurt or dishonour; or who shall begin, excite, cause, or join in any sedition ; or who, being present at any mutiny or sedition, does not use his utmost endeavours to suppress the same, or, coming to the knowledge of any mutiny, or intended mutiny, does not give information to his commanding officer; or who shall strike his 72. - superior officer, or draw, or offer to draw, or lift up any weapon or offer any violence against him, being in the execution of his office; or who shall disobey any lawful command of his superior officer, is guilty.of mutiny. . . . MUTULE, in Architecture, a kind of square modillion, set under the corniche of the Doric order. - - MYA, a genus of insects of the vermes testacea class and order. There are about twenty-five species. M. declivis has a brittle semi-transparent shell, sloping downwards near the open end ; the hinge slightly prominent. It is found about the Hebrides, where the fish is in great esteem. M. margaritifera, is found in mountainous rivers, and about cataracts. It is about five inches long, and half as many broad; and it is noted for producing mother-of-pearl and pearls; the latter is said to ; i. disease of the fish analogous to the stone in the human Ody. MYAGRUM, Gold of Pleasure, a genus of the tetradynamia siliculosa class and order. There are ten species. The sati- vum is cultivated in Germany for the sake of the expressed oil of the seeds. MYCTERIA, the Jabira, a genus of birds of the order gral- lae. The American jabira is nearly six feet in length. It abounds in the levels of Cayenne, and other parts of South America, feeds upon fish, of which it devours immense quan- tities, and builds in vast trees, laying only two eggs. It is extremely wild, and when young is used for food. M. Asiatica is likewise a very large bird, inhabits the East Indies, and feeds on snails. MYOPES. Those who by a natural defect have the cornea and crystalline humour too convex, are called myopes. This figure, increasing the quantity of refraction, tends to render the rays of such pencils as are formed in the eye more con- vergent, so that the point where these same rays meet is on this side of the retina. , Myopes see distinctly those objects only which are near, which send towards the eye rays more divergent, and thereby less disposed to converge, through the effect of refraction in the crystalline and other humours. This imperfection is remedied by the use of a glass slightly COIl CaV6. MYOXUS, the Dormouse, in Natural History, a genus of mammalia, of the order of glires, four grinders in each Jaw; long whiskers, tail cylindric, bristly, and thicker towards the end; legs of equal length; fore feet with four toes. These animals feed only on vegetables, and burrow in the ground, in which they continue during the winter in a torpid state. They are nocturnal, sleeping in their habitations the greater part of the day; they carry food to their mouths with their fore paws, sitting erect; and advance by leaps of several feet at a time, instead of walking. There are four species. The fat dor- mouse, found in Germany and Rassia, has much of the man- ners of a squirrel, haunting trees, and feeding on fruits and nuts, which it stores for its winter consumption. It was highly valued by the Romans as an article of food. It is six inches long to the tail, which is about four: it is not easily tamed. The common dormouse, nearly of the size of a mouse, and inhabits thick hedges, making its nest in the bollow of some tree, forms a hoard for the winter, during which it is for the greater part abstinent and torpid. It is occasionally roused by the intervention of temperate days, recurs to its stock, and then returns to its slumbers, till spring recovers it to daily exertion. MYRIAD, the number ten thousand. MYRISTICA, Nutmeg Tree, a genus of the dioecia synge- nesia class and order. Natural order of lauri. There are three species, of which M. aromatica, aromatic or true nutmeg tree, grows to a considerable size in the East Indies. The leaves are aromatic; and if the trunk or branches be wounded, they will yield a glutinous red liquor. - MYRMECOPHAGA, the Ant Eater, a genus of mammalia, of the order bruta. They subsist on insects; thrusting their tongue into a nest of ants, the glutinous substance, which exudes from it serves to attach to it in extricably numbers of them, and when the animal perceives that he has secured a sufficient number, he retracts his tongue, and swallows his victims. There are seven species. - - MYRMELEON, Lion Ant, a genus of insects of the order 8 Q - 702. M. Y. R. M Y x DICTIONARY OF MECHANICAL SCIENCE. neuroptera. There are 16 species. The Myrmeleon in the larva state preys on 'ants and lesser insects; and for the pur- pose of ensnaring them sinks itself into the sand, and forms a kind of funnel or pit in which it lies buried. the head only appearing above the sand. . \,; MYROXYLUM, a genus of the monogynia order, in the decandria class of plants. There is but one species, the peruiferum, a native of Peru, and the warmer parts of Africa. It is this shrub that yields the balsam of Peru, which is said to be extracted from it by coction in water. This balsam, as brought to us, is nearly of the consistence of thin honey, of a reddish-brown colour inclining to black, and an agreeable aromatic flavour. MYRRH, a gum resin brought from the Levant and East Indies, and used in medicine. It is hard, dry, glossy, of a reddish brown colour, with an admixture of yellow : transpa- rent or opaque; of a peculiar strong smell, and a bitter, some- what biting taste. ...With water it forms a yellow opaque soluber, and by distillation yields an essential oil. MYRTUS, Myrtle, a genus of the icosandria monogynia class and order. Nat. ord. hesperideae. There are thirty-six species, and many varieties. This genus is composed of small trees and shrubs; flowers in some solitary, with two scales at the base ; in others, forming opposite corymbs or panicles, axillary or terminating. The common myrtle is a native of Asia, Africa, and the south of Europe. The allspice tree is | about thirty feet in height, and two in circumference. It is a native of New Spain and the West Indies. The flavour and fruit have a highly aromatic fragrance. . . . . . MYTHOLOGY, the history of the fabulous gods and heroes of antiquity, with the explanations of the mysteries or allego. ries couched therein. - - MYTILUS, the Mussel, a genus of insects of the vermes tes- tacea class and order. There are between fifty and sixty spe- cies. M. margaritiferus, which inhabits the American and Indian seas, is about eight inches long, and something broader; the inside is beautifully polished, and produces true mother-of- earl, and frequently the most valuable pearls. M. edulis inhabits European and Indian seas, found in large beds, adhering to the other bodies by means of a long silky beard: the fish affords a rich food, but is often noxious to the con- stitution. -- MYXINE, the Hag, a genus of insects belonging to the order of vermes intestina. - N. N A I N ABOB is a title in the East Indies, which in its origin sig- nified deputy, and was first assumed by subordinate governors, who ruled over districts under the soubah, or governor of a pro- vince. In the declension of the power of the Mogul, many of the nabobs obtained independent authority. NACRE, or Mother of Pearl, is the inner part of the shell of the pearl muscle. This is of a brilliant and beautifully white colour, and is usually separated from the external part by aqua-fortis, or the lapidary’s mill. Pearl muscle shells are on this account an important article of traffic with China and many parts of India, as well as to the different countries of Europe. They are manufactured into beads, snuff-boxes, but- tons, and spoons, fish and counters for card players, and innu- merable other articles. The pearl muscles are not considered good as food; though after having been dried in the sun, they are sometimes eaten by the lower classes of people in the coun- tries near which they are found. NAILS, in Building, are small spikes of iron, brass, &c. for fastening pieces of wood together. Among the Hebrews, nails were anciently used for cancelling bonds, by striking them through the writing. The several sorts of nails are very nume- rous; as, 1. Back and bottom nails, with flat shanks to hold fast and not open the wood. 2. Clamp-nails for fastening the clamps in building, &c. 3 Clasp-mails, whose head clasping and sticking into the wood, render the work smooth, so as to admit a plane over it. .4. Clench-mails, used by boat and barge builders. 5. Clout-nails, used for nailing on clouts to axle- trees. 6. Deck-nails. , 7. Dog-nails, for fastening hinges on doors, &c. 8. Flat-points, much used in shipping, and are pro- per where there is occasion to draw and hold fast, and no eonveniency of clenching. 3. Jobent-mails, for nailing thin plates of iron to wood, &c. 10. Lead-nails, for nailing lead, leather, and canvass to hard wood. 11. Port-nails, for nailing hinges to the ports of ships. 12. Pound-nails, which are four square, used for paling. 13. Ribbing-nails, principally used in ship building, for fastening the ribs of ships in their places. 14. Rose-nails, which are drawn four square in the shank, and commonly in a round tool. 15. Rother-nails, which have a full head, and are chiefly used in fastening rother irons to ships. , 16. Round-head nails, for fastening on hinges, or for any other use where a neat head is required. 17. Scupper- nails, which have a broad head, and are used for fastening lea- N A I ther and canvass to wood. 18. Sharp nails, with sharp points and flat shanks, for nailing soft wood. 19. Sheathing-nails. 20. Square-nails, used for hard wood, and nailing up wall- fruit. 21. Tacks, &c. Nails are said to be toughened when too brittle, by heating them in a fire shovel, and putting some tallow or grease among them. t ... * The following table exhibits Mr. Bevair's experiments on the adhesion of nails when driven into dry Christiana deal, at right angles to the grain of the wood. - Pounds re- Number of lbs. Inches Inches forced quired to Avoirdupois. long. into the wood. extract. Fine sprigs,. . . . . . . . 4,560 . . . . 0°44 . . . . 0-40 . . . . 22 Ditto, ... . . . . e e s • * a . 3,200 . . . . 0'53 . . . . 0-44 . . . . 37 Threepenny brads, .. 618 . . . . 195 . . . . 0°50' . . . . 58 Castiorn nails, ..... 380 . 1°00 . . . . 0°50 . . . . 72 Sixpenny nails, . . . . 73 . . . . 2'50 . . . . 1:00 . . . . 187 Ditto, . . . . . . tº e e º 'º e s e — .... — . . . . 150 . . . . 327 Ditto, . . . . . . . . . . . . . . ... — . . . . . — . . . . 2:00 . . . . 530 Fivepenny nails, .... 139 . . . . 2:00 . . . . 1:50 . . . . 520 The percussive force required to drive the common sixpenny nails to the depth of 1% inch into dry Christiana deal with an iron weight of about 64 lbs. was four blows falling freely the space of twelve inches, and the steady pressure required to produce the same effect was 400 lbs. A sixpenny nail driven one inch across the grain into dry elm required 327 lbs. to extract it; driven end ways, or longi- tudinally, it required 257 lbs. for its extraction: driven end- ways two inches into Christiana deal, it was drawn out by a force of 257 lbs. ; but driven in one inch only in the same di- rection, it was extracted by 87 lbs. The relative adhesion, therefore, when driven transversely or longitudinally, is as 100 to 78, or about 4 to 3, in dry elm ; and as 100 to 46, or as 2 to 1 in deal. To extract a common sixpenny nail from a depth of one inch out of dry oak, required . . . . . . . . . . . . . . . . . ... 507 lbs. Dry beech,. . . . . . . . . . . . . . . ... . . . . . . 667 lbs. Green sycamore, ... . . . . © e º 'º e º 'º .... 312 lbs. A common screw of 1-5th of an inch diameter was found to have an adhesion about three times that of a sixpenny nail- The resistance to the entrance of a nail was found to be to that of extraction, in some experiments, as 6 to 5. N A. P. N A Tº 703 DICTIONARY OF MECHANICAL SCIENCE. NAIL is also a measure of length, being the sixteenth part o a yard, - - § APHA, a name given by many of the writers in pharmacy to orange-flower water. - - NAPHTHA, is a native combustible liquid, which differs from petroleum, which is obtained by the distillation of coals, in be- ing purer and lighter. It is found abundantly near the Cas- rºº and in some places in Italy and Sicily, and is burnt 8S Olſ. NAPHTHA, or Rock Oil, is a yellow or brownish bitumi- nous fluid, of strong penetrating odour, somewhat greasy to the touch, and so light as to float even on spirit of wine. By exposure to the air, the consistence of naphtha is increased, and it passes into petroleum. There are copious springs of naphtha at Baku, on the shore of the Caspian sea; and also in some parts of Italy, particularly at Monte Ciaro, near Riacenza. At Pitchford, in Shropshire, extensive strata or beds of sandstone are saturated with this mineral fluid, which is obtained from the stone by distillation, and is sold as a remedy against sprains and rheumatism, under the name of Betton's British Oil. By the Persians and Russians naphtha is used internally as a cor- dial. On the shores of the Caspian it is burnt in lamps instead of oil ; and in some countries it is used in the composition of warnish, for the purpose of rendering it more shining. It is the property of naphtha to burn with great readiness, and a white flame, leaving little residuum. w NAPIER, John, Baron of Merchiston, in Scotland, was an excellent mathematician, and the inventor of logarithms, in the sixteenth century. w It is not, however, on this invention only that his fame is established; for he also made considerable improvements in spherical trigonometry, &c. particularly by his catholic or uni- versal rule, being a general theorem by which he resolves all the cases of right-angled spherical triangles in a manner very simple and easy to be remembered, namely, by what he calls the five circular parts. See CIRCULAR PARTs. His construc- tion of logarithms too, beside the labour of them, manifests the greatest ingenuity. Kepler dedicated his Ephemerides to Na- pier, which were published in the year 1617; and it appears from many passages in his letter about this time, that he ac- counted Napier to be the greatest of this age in the particular department to which he applied his abilities. NAPIER’s Rods or Bones, (as in the following figure) a method contrived by Lord Napier, for the more easy performing of the arithmetical operations of multiplication, division, &c. These 7 || 8 6 || 7 || 8 || 9 9 7. O || 1 || 2 || 3 A 2 3. 27. 6 9 rods are five in number, made of bone, ivory, horn, wood, or pasteboard, &c. Their faces are divided into nine little squares, each of which is parted into two triangles by diagonals. In these little squares are written the numbers of the multipli- eation table; in such manner as that the units or right-hand figures are found in the right-hand triangle; and the tens, or left-hand figures, in the left-hand triangle. To multiply num- bers by Napier's bones, dispose the rods in such manner, as that the top figures may exhibit the multiplicand, and to those ..on the left hand join the rod of units: in which seek the right- hand figure of the multiplier; and the numbers corresponding to it, in the squares of the other rods, write out, by adding the several numbers occurring in the same rhomb together and their sums. After the same manner write out the numbers corresponding to the other figures of the multiplier, disposing them under one another as in the common multiplication; and lastly, add the several numbers into one sum. For example, suppose the multiplicand 5978, and 5978 the multiplier 937. From the outermost triangle on 937 the right-hand figure, which corresponds to the right- - . hand figure of the multiplier 7, write out the figure 6, 41846 placing it under the line. In the next rhomb to- 17934 ward the left, add 9 and 5; their sum being 14, 53802 : write the right-hand figures 4 against 6; carrying — º- the left-hand figure 1 to 4 and 3, which are in the 5601386 next rhomb : join the sum 8 to 46 already set down. . After the same manner, in the last rhomb, add 6 and 5, and the latter figure of the sum 11, set down as before, and carry 1 to the three found in the left-hand triangle; the sum 4 join as be- fore on the left-hand, 1846. Thus you will have 41846 for the product of 5978 by 7. And in the same manner are to be found the products for the other figures of the multiplier; after which the whole is added together as usual. . . . . . NARCISSUS Poeticus, or Pseudo NARCIssus. These are much cultivated in gardens for the sake of the flowers. The florists have by culture made several varieties, as double blossoms, which are great ornaments. The season for planting the bulbs of Narcissus of all kinds is the month of October: º will grow well in any soil, and thrive best under the shade Of trees. : NARCOTICS, in Medicine, are soporiferous drugs, which bring on a stupefaction; as the poppy or opium; and those º from mandragoras, hyoscyamus, stramonium, and atura. . NARDUS, a genus of plants belonging to the triandria class, and in the natural method ranking under the fourth order, Gramina. Both as a medicine and luxury, this plant was highly valued by the ancients. Among the Romans, this oint- ment of nard was used at baths and feasts as a favourite per- fume. Its value is evident from that passage of scripture, which informs us that our Saviour's head was anointed with a box of it, with which Judas found fault. NARWAL, or The Sea UNIcorn, is a marine animal from twenty to thirty feet in length, with a long, tapering, twisted, and pointed weapon of ivory in front of the head. It has a small fin on each side of the breast; in place of fore feet, an ho- rizontally flattened tail, and a spiracle or breathing-hole on the highest part of the head. The skin is white, variegated with numerous black spots on the upper part of the body; and the weapon is generally from five to eight feet in length. These animals are found in the Greenland seas, and they occasionally migrate southward of the British coasts. Their name of narh- wal signifies a whale that subsists on dead bodies. The Green landers pursue the narwals as they do other whales, chiefly on account of the oil which they obtain from them. This is considered in many respects superior to the oil of the great whale, and is used by them both with food, and to burn in their lamps. These people also eat the flesh of the narwal. - NATRON, native carbonate of soda. It is found in vast abundance in the lakes near Alexandria in Egypt. The exist- ence of natron in the midst of plains, in the waters of marshes and lakes which cover them, is one of the most interesting facts in geology. We find this phenomenon every where in the midst of vast deserts, which occur in so many places of our globe. From all that we know of this mineral production in Egypt, Arabia, Persia, India, Thibet, China, Siberia, the plains near the Caspian and Black Seas, in Asia Minor, in Hungary, and at Mexico, we have reason to believe that it occurs in the same circumstances and with the same relation. It is found every where in the midst of sands, mixed with clay and marl, and accompanied with other salts, of which common salt is the most constant. In warm weather the natron is constantly efflorescing at the surface of the soil. The origin of this na- tron cannot with certainty be determined. The opinion which will most naturally present itself is, that natron occurs already formed in the sand or clay at a certain depth, along with the different salts with which it is mixed, and that the waters, by filtering through the mass of earth, in order to regain their le- vel, laid hold of those substances, which they carried to the sur- face of the soil. This opinion, however, cannot be supported by any positive observation, because no pits have been dug which confirm it, in the different places where matron appears | at the surface, So also, no where in the deposits of rock salt 704 N A U. N A U DICTIONARY OF MEGHANICAL sciencI. is carbonate of soda found; and the waters of the sea are equal- ly destitute of it. Nevertheless, on the sea-shore natron is formed,though in a small quantity, efflorescing at the surface; and here its origin must be attributed to the decomposition of the muriate of soda. This decomposition may be effected in various ways, and advantage is taken of this in the manufacture of artifi- cial subcarbonate of soda, in which several methods, more or less perfect, haye been successfully employed. It is probable, therefore, that it is from the natural decomposition of muriate of soda that natron is formed. The matron in Egypt, in the opinion of Mr. Berthollet, is produced by the reciprocal action of mu- riate of soda and carbonate of lime, assisted by efflorescence. The lakes of Egypt contain a great quantity of muriate of soda, and they occur in the midst of a calcareous formation, the rocks of which project here and there through the sand which covers them. Masses or beds of gypsum also occur, which probably accompany the deposits of rock salt which the waters traverse before arriving at the lakes. The same explanation will probably be found to be applicable to many otherinstances of the formation of natron, or mineral carbonate of soda. NATURAL DAY, is the time the sun takes in passing from the meridian of any place, till it comes round to the same me- ridian again; but the natural days are not equal to one an- other; and equation of time, is the difference between the mean length of the natural day, (or 24 hours) and the length of any single day measured by the sun's motion, or between mean time and apparent time. For any natural day is the time in which the earth performs one revolution round its axis, and such a portion of the second as is equal to the sun's increment of right ascension for that day; but the sun's daily, increments of right ascension are unequal, therefore the additional portion of the second revolution will sometimes be greater and sometimes less, and consequently, the times in which the natural days are completed will be unequal. If the sun were to move uniformly round the equator in the same time in which it appears to de- scribe the ecliptic, its apparent daily motion would be a mea- sure of mean time: for the natural days in that case being liable to no variation, either from the inclination of the sun's orbit, or the irregularity of its motion, must be equal. NATURAL HISTORY, may be divided into two heads; the first teaches us the characteristic or distinctive marks of each individual object, whether animal, vegetable, or mineral: the second makes us acquainted with all its peculiarities, as to its habits, its qualities, and its uses. - NAUSEA, or SickNess, arises generally from something which irritates the stomach. ! NAUTICAL INDICATOR, for finding the Latitude, Longi- tude, and Variation, invented by James Hunter, member of the Glasgow Philosophical Society.—The indicator consists of a stand supporting a circular plate of polished brass, about 14 inches in diameter, representing the horizon, and marked and numbered accordingly with the proper divisions. This horizon is surmounted by a semicircular plate, as a meridian, set at right angles to the plane of the horizontal plate, properly divided and furnished, with an index attached to a nonius in- dicating minutes. This meridian plate is cut out at the centre to allow room for a pivot, or hinge, for other parts of the indi- cator. On one side of this meridian are placed two quadrants, and on the other side one, similarly divided as the meridian, and furnished with a similar index and monius. These quad- rants are moveable on a pivot, or hinge, rising perpendicular from the centre of the horizontal plate; or, agreeing to this centre, they are singly moveable on the pivot, but capable of being attached at any relative distance, and retained in that situation by a screw, binding together tails attached for the purpose. To the east and west points of the horizontal plate is attached a horary circle, divided into hours, &c. circle represents the daily path of the sun, and it may be furnished with a nonius, as other parts are. This circle is so attached to the horizontal plate, that it can be moved parallel to it, to suit the sun's declination; this is effected by the circle being attached to two tangent plates, which by grooves slide on the projections from the horizontal plate by means of screws passing through and working in these projections, and carrying the tangent plates, and with them the horary circle, to the degree of the sun's declination. This degree is indicated on a This horary. scale of tangent divisions on the tangent plates, and as such tangents are of various lengths, an expanding vernier is used to adjust them. Its expansion is effected by friction wheels an springs working against a proper curve. 2 Elevation of Hunter's Nautical Indicator. References to the Figures.—1, 2, 3, the quadrants of altitude, and also arches of azimuth circles; 4 is the apparent horizon, on which the azimuths and amplitudes are given; 5, the horary circle, on which the hours and minutes of time are given; 6, the scale of declination, with an expanding vernier; 7, 8, 9, sliding indexes, with their respective thumb screws; 10, a sliding stop; 11, continual screws for setting the indexes of declina- tion ; S, the support, on which the instrument turns; M, the meridian.—Note. The same references agree both to the plan and elevation. - Use of the Indicator.—Its use is to discover the latitude, longitude, and variation of the compass, without a meridian observation; or to find the whole path of the sun and the ship's place, by having ascertained a small portion of his path. Thus the indicator will frequently supersede the necessity of calcu- lations—will prove their accuracy—or correct their inaccura- cies, and enable an ordinary seaman to supply the place of captain or mate, in case of necessity. It will be of the most important utility in case of inconstant, stormy weather, when observations of the meridian altitude of the sun are unat- tainable. Manner of using the Indicator.—1st. By the side screws and scales, the horary circle is to be so adjusted to the declination of the day of the month, as marked in the tables of declimation. 2d. An observation of the sun by Hadley’s or other quadrant, is to be taken, and the moveable quadrant for that from the meridian, adjusted by its index to the observation. Also, an hour, or any practical time after, another observatien is to be taken and noted on the other moveable quadrant in the same manner, noting the time elapsed between the observation by any well-going watch, and then connecting both to move toge- ther. Then the indices of the two quadrants are to be applied to the scale on the edge of the horary circle, at the distance noted by the intervening time, and at such part of the circle, that both indices will accuratcly touch its edge. In this con- tact each index will indicate the true time of the observation. The index on the meridian, brought into contact with the horary circle, will give at the same time the sun’s true meri- dian altitude, and the latitude of the ship's place. The place of the quadrant on the horizontal plate, will give the true bearing. of the sun at the time of observation. The true time of observation at the ship is to be compared by the chronome- ter with the time at the radical meridian, and the diſſerence reduced into degrees and minutes, gives the longitude—the difference between the true bearing of the sun, found as above, and the bearing given by the compass, is equal to the variation at the place of observation, and the index on the meridian gives the latitude. Thus the decision, or ascertaining of the N A tſ N A Wº 705 DICTIONARY OF MECHANICAL SCIENCE, three great points, is facilitated, and nearly reduced to inspec- tion, viz. latitude, longitude, and variation. If the one obser- vation is taken A. M. and the other P. M. the moveable quadrant on each side is used. If both observations are obtained P. M. the quadrant nearest the meridian is first used. - Plan of Hunter's Nautical Indicator. & ſº º © - * In the year 1817 Mr. Hunter exhibited his invention in Glasgow; in November, 1823, there appeared in the London Magazine the following notice of an instrument for finding the Latitude at once, without the help of Logarithms or Calcula- tions, from two observations, taken at any time of the day:— The inventor of this instrument, Joseph Bordwine, Esq. pro- fessor of fortification at the East India Company’s Military College at Addiscombe, took out a patent for his disco- very, and the Court of Directors issued orders that this instrument be henceforth used throughout the whole of their naval department. Mr. Bordwine’s nautical instrument is in- tended to put within the reach of every commander of a vessel, the solution of that important problem in navigation, viz. the determination of the latitude by two observations of the sun, or other celestial body, taken at any period of the day, a prob- lem which has engaged the attention of scientific men for a long time past, with the view of rendering the forms of calcu- lation more simple than by the old method. The instrument does away with calculation altogether, giving the results in itself. It is formed of four circular arcs, (the greatest about nine inches in diameter,) having a common centre, and tra- versing about each other. On two of these are scales for the declination of the object observed, and on the other two scales for the altitudes which are taken for the usual instruments, quadrant, &c. There is also a fourth semicircle, fixed in posi- tion, for the time elapsed between the observations. In work- ing it, the declination for the day is set off, the time adjusted, and the verniers, marking the observed altitudes, brought together, when the instrument will immediately shew, 1. The latitude of the place of observation, to 15" of a degree. 2. The distance in time from noon of either observa- tion, to 2" of time, which compared with a chronometer will give the difference of longitude. 3. The true azimuth, which, compared with a compass bearing, will give the variation of the magnetic pole. The operation may take about three or four minutes, there being no other calculation required than the usual correctness for dip, refraction, &c. in the altitudes; and the like for the declination, from the Nautical Almanack, to adapt it to the place of observation: these being reductions which must take place under any solution of the problem, whether by the calculated forms, or by instrument. Two or three hours’ instruction will make any master of a vessel com- petent to use it.—This account of Bordwine’s instrument amounts also to a demonstration, that it is the same as Hunter's, which, however, claims, priority of date for its invention. NAUTILUS, in Natural History, a genus of the vermes tes- tacea class and order. The N. pompilius inhabits the Indian and African oceans, often very large, and finely variegated with brown flexuous streaks, spots, and marks under the outer covering, which is white; within of a most beautiful pearly gloss. Of this species, the inhabitants of the East make drink- ing cups. The shell of N. papyraceus is no thicker than paper, and the fish is not fastened to it. When it is to sail, it expands two of its arms on high, and between these supports a membrane which it throws out on this occasion ; this serves for its sail; and the other two arms it hangs out of its shell, to serve occasionally either as oars or as a steerage, but this last office is generally served by the tail. If a storm arises, or any thing gives them disturbance, they draw in their legs, and take in as much water as makes them specifically heavier than that in which they float, and they sink to the bottom. When they rise again, they void this water by a number of holes, of which their legs are full. - - - NAVE, in Architecture, denotes the body of a church, or the place where the people are seated, reaching from the rail or baluster of the choir to the chief door. v - NAve of a Wheel, that short thick piece in the centre of a wheel, which receives the end of the axle-tree, and in which the ends of the spokes are fixed. - NAVIGATION, the art of sailing, or of conducting a vessel through the ocean, is usually divided into navigation common, and navigation proper; the former relating to what is other- wise called coasting, or traversing the coast or shore of a country, and in which the navigator seldom loses sight of land. And the other, to those voyages made from one country to an- other, through the trackless paths of the ocean. The origin of navigation, like that of all the arts and sciences of ancient date, is lost in obscurity, some attributing it to one nation, and some to another. The Phoenicians, particularly those of Tyre, are now, however, more generally considered as the first people who made any great advances in this important art. These were afterwards followed up by the Carthaginians, who dis- covered the Fortunate or Canary Islands, and even, according to some authors, America was visited by this enterprising peo- ple, but of this there is not sufficient proof. From Carthage and Tyre commerce and navigation were transferred to Alex- andria, which when under the Romans was only inferior to Rome itself, the latter being supplied with its merchandise wholly from the magazines of the former. Constantinople be- came afterwards the centre of commerce, and navigation was for a long time pursued with great ardour by the merchants of that city; after this time it began to spread itself, though slowly, amongst the several European cities and nations. Genoa and Venice are particularly distinguished for the active part they took in promoting this important branch of human know- ledge. The crusades, however, contributed in a great mea- sure to its revival, and the Genoese, the Pisans, and Venetians, who furnished transports to those holy mariners, pushed their discoveries to a great extent. The inventor of the mariner's compass in the fourteenth century completed the wants; of sailors. Columbus and Vasco di Gama immortalized them- selves in the fifteenth century, and Cook in the eighteenth, by their noble discoveries. . . . . . A few plain truths will set the whole art of navigation in a clear light to the most inexperienced: 1. In whatever direction a ship sails, she must steer along some rhumb or point of the compass. Thus, supposing she were going to sail from New Guinea to Niphon, one of the Japan islands, in long. 150° east, her course would be due north along the meridian of 160° east long. If she were going to sail from New Holland to Madagascar, her course would be due west, in the latitude of about 20° south: and so on of her course in any other direction between the four cardinal points of the mariner's compass. Hence, . * . - • * * : . . 2. In plane Sailing, the angle formed by the meridian and rhumb that a ship sails upon, is called the ship’s course. Thus, if a ship sails on the N. N. E. rhumb, then her course will be 22 deg. 30 min. ; and so of others. . . . . 3. The distance between two places lying on the same parallel, reckoned in miles of the equator, 0. the distance of one place from the meridian of another, counted as above on the parallel passing over that place, is called meridional distance, which in plane sailing goes under the name of Departure. -- - 4. Let A, fig. 2, denote a point to the earth's surface, A C its meridian, and AD the parallel of latitude passing through. - 8 R. 706 N A V TN A W - DICTIONARY OF MECHANICAL scIENCE. . to the departure BD it; and suppose a ship to sail from A on the N. N. E. rhumb, till she arrives at B, and through B, draw the meridian B D, (which by the princi- ples of plane sailing must be parallel to CA,) and the parallel of latitude B C, then the length. of A B is called her distance; A C or B D will be her difference of latitude or northings, C B will be her departure or easting, and the angle C A B will be the courses. 5. Since the dis- tance, difference of latitude, and departure, form a right-angled triangle, in which the oblique angle opposite to the departure is the course, and the other its complement, therefore, having any two of these given, we can, by plane trigonometry, find the rest; and hence arise the following cases of plane sailing. Case 1. Course and distance given, to find the difference of latitude and departure. f Example. Suppose a ship sails from the latitude 30 deg. 25 min. north, N. N.E. 32 miles, fig. 3, required the difference of latitude and departure, and the latitude come to, (by right- angled trigonometry,) we have the following analogy for finding the departure, viz. - As radius ...... tº e º e º ſº tº ſº e º e s a e e º ºs e s & e º 10:00000 to the distance A C . . . . . . . . . . . . . . . . . . . . . . 32 . . . . so is the sine of the course A 22 deg. 30 min. ....... 1.50515 9°58284 to the departure B C ................ . . 12'25 . . . . 1'08799 so the ship has made 12°25' got so far eastward of her meridian. Then for the difference of latitude or northing the ship has made, we have (by rect- angular trigonometry) the following analogy, viz. As radius. . . . . . . . . . * G - e º g g º O e - e º ſº º º & e e º e e e º e º e e 10:000000 to the distance A.C. . . . . . . . . . . . . . . . . . . . . . 32 .... 1-60515 so is the sine of the course A 22 deg. 30 min........ 9.58284 to the difference of lat. A B. . . . . . . . . . . . . . . . . .29'57 1-47077 so the ship has differed her latitude, or made of northing 29'57 minutes. And since her former latitude was north, and her difference of latitude also north, therefore, To the latitude sailed from ............ . . . . 30° 25' 0" N. add the difference of latitude ............... 00 29 57 and the sum is the latitude come to . . . . . . ... 30 54 57 By this case are calculated the tables of difference of lati- tude and departure to every degree, point, and quarter-point, of the compass. - - Case 2. The course and difference of latitude being given, to find distance and departure. Example. sails NE by N} easterly, (fig. 4,) till she comes to the latitude of 46 deg. 55 min. north: required the distance and departure made good upon that course. Since both latitudes are north- erly, and the course also northerly, therefore, From the latitude come to ...... . . . . . . e e o a v e a e . . . . . 46° 55' subtract the latitude sailed from........ . . . . . . . . . . . . 45 25 and there remains. . . . . . . . . . . . . .................... I 30 the difference of latitude equal to 90 miles. And (by trigono- º have the following analogy for finding the departure , 1912. As radius, sine 90°.............................. 10-00000 is to the diff of lat. AB ................. 90 . . . . ] '95424 so is the tangent of course A 33:22 ..... e e o ºs e e e º e s 9-91.404 e 73-84 1°86828 ; the ship has got 73.84 miles eastward of her former meri- I aſl. the following proportion, viz. As radius . . . . . . . . . . . . . . . . . . . . . . . . . . . tº e e º e º 'º º 10:000000 is to the secant of the course .............. 39'22 10° 11176 so is the diff of lat. A B . . . . . ............ 90 m. 1'954.24 to the distance A D . . . . . .............. ... 1164 206600 miles of departure easterly, or has A ship in the latitude of 45 deg. 25 min. north, Again, for the distance A D, we have (by trigonometry) Case 3. The difference of latitude and distance given, to find course and departure. Example. A ship sails from the latitude of 56 deg. 50 min. north, on a rhumb between south and west, 126 miles, and she is then found by observation to be in the latitude of 55 deg. 40 min. north ; required the course she sailed on, and her departure from the meridian. (Fig. 5.) Since the latitudes are both north, and the ship sails towards the equator, therefore, From the latitude sailed from.... . . . . . . . . . . . . . . . . . . 56° 50' subtract the observed latitude ...... . . . . . . . . . . . . . . . 55 40 and the remainder... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I 1() equal 70 miles, is the difference of latitude.—By rectangular trigonometry we have the following proportion for finding the angle of the course F, viz. 1 As the dist. Sailed D F . . . . . . . . . . . . . e e a e s e o e e 126° 2' 10037 is to radius . . . . . tº e º e º e e s e º e º 'º e º & e g & © tº tº tº e º e 10:00000 so is the diff, of lat. FD. . . . . . . . . . . . . . . . . . . . . . 70 l'84510 to the co-sine of the course F. . . . . . . . . . . . . . . .56° 15' 9"74473 which, because she sails between south and west, will be south 56 deg. 15 min. west, or SW by W. Then, for the departure, we have (by trigonometry) the following proportion, viz. As radius sine 90° ...... º e o e s s 10-00000 is to the dist. sailed D F ................... so is the sine of the course F . . . . . . . . . . . . . . 1269 2-10037 56 15' 991985 *- to the departure, DE. . . . . . . . . tº g g º º º . . . . . . . . . 104°8 2:02022 consequently she has made 104.8 miles of departure westerly. Case 4. The difference of latitude and departure given, to find the course and distance. Example. A ship sails from the latitude of 44 deg. 50 min. north, between south and east, till she has made 64 miles of easting, and is then found by observation in the latitude of 42 deg. 56 min. north; required the course and distance made good. Since the latitudes are both north, and the ship sailing towards the equator, therefore, From the latitude sailed from . . . . . . © e º O s e º e º e . . . . 44° 50' N. take the latitude come to . . . . . . . . . . . . . . . . . . . . . . . . . 42 56 and there remains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 54 equal to 114 miles, the difference of the latitude or southing. Aºg.-1. zº y G B IB Axeo f/2". S s § s § § Ä § - S *-*- K A&sſ, 64. L. A. A. - In this case (by trigonometry) we have the following proportion to find the course K G L, fig. 6,) viz. As the dist. of lat. G. K. . . . . . . . . . . . . . . . . . . . 1149 2-05690 is to the radius . . . . . . . . . . . . . . . . . . e e º gº tº e º o 10-00000 so is the departure K L. . . . . . . . . . . . . . . . . . . . 64 1'80618 to the tangent of the course G. . . . . . . . . . . . . . 29°19' 9-74928 which, because the ship is sailing between south and east, will be south 29 deg. 19 min. east, or SS E3 east, nearly. Then for the distance we shall have (by rectangular trigonometry) the following analogy, viz. As radius . . . . . . . . . . . . . . . . . . . . . . . . . e e s tº e s e a sº e º s > * 10:0000 is to the diff of lat. G. K. . . . . . . . . . . . . . . . . 1149 205690 so is the secant of the course. . . . . . . . . . . • . . 290 19' 10-05952 to the distance G L . . . . . . . . . . . . . . . . . . . . . . 132-8 2' 11642 consequently the ship has sailed on a S SE; east course 130.8 miles. - N A W N A V DICTIONARY OF MECHANICAL scIENCE. 707 Case 5. The distance and departure given, to find course and difference of latitude. Example. A ship sails from the latitude of 34 deg. 24 min. north, between north and west, 124 miles, and is found to have made of westing 86 miles; required the course steered, and the difference of latitude or northing made good. In this case (by trigonometry) we have the following proportion for finding the course A D B, fig. 7, vºz. - As the distance A D . . . . . . . . . . . tº º ſº tº dº tº gº tº tº º º O & 1249 2.0934. is to radius sine 90° . . . . . . . . . . . . . tº e e º O p q e º e & 10'00000 so is the departure A B . . . . . . . . . . . . . . . . . . . . . 86 193450 to the sine of the course D . . . . . . . . . . . . . . . . . . 43 54' 9'84108 so the ship's course is north 33 deg. 45min. west, or NW by N4 west nearly. Then for the difference of latitude we have (by rectangular trigonometry) the following analogy, viz. As radius sine 90°. . . . . . . . . . . . . . . . . . . . . . . . . . 10:00000 is to the distance A D . . . . . . . . . . . . . . . . . . . . . . 124° 2'09342 so is the cosine of the course . . . . . . . . . . . . . . . . 43°54' 9-85766 to the diff of lat. B D . . . . . . . . . . . . . . . . . . . . . . 89 35 1"95.108 which is equal to 1 degree and 20 minutes nearly. Hence, to find the latitude the ship is in, since both latitudes are north, and the ship sailing from the equator, therefore, To the latitude sailed from ........................ 349 24! add the difference of latitude...................... l 29 the sum is . . . . . . . . . . . . . . . . . . . . . . . . . . . . tº º te º ºs ºr e º ſº e tº 35 53 the latitude of the ship is in north. Case 6. The course and departure given, to find distance and difference of latitude. Example. A ship at sea, in the latitude of 24 deg. 30 min. south, sails SE by S, till she has made of easting 96 miles; required the distance and difference of latitude made good on that course. In this example (by Case 2.) we have the following propor- tion for finding the distance, fig. 8, viz. As the sine of the course G ........... ... 33° 45' 9-74474 is to the departure H M .................. 96 I '98227 so is radius . . . . . . . . . . . . . . . . . . . . . . . . • * * * * - 10:00000 to the distance G. M. . . . . . . . . . . . . . . . . . . . . . 172 8 2.29753 Then, for the difference of iatitude we have (by rectangular trigonometry) the following analogy, viz. As the tangent of course . . . . . . . . . . . . . . . . 33° 45' 5'82489 is to the departure H M . . . . . . . . . . . . . . . . . . 96 198227 so is radius ........ • * c e s tº e º e g tº © e º º e C & e º e 10:00000 to the diff. of lat. G. H. .................. 143 7' 2-15738 equal to 2 deg. 24 min, nearly. Consequently, since the lati- tude the ship sailed from was south, and she sailing still towards the south, To the latitude sailed from.............. * - º e s tº e º e e 24° 30' add the difference of latitude .......... tº e º ſº tº e º e . . . . 2 25 and the sum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 55 is the latitude she is come to, south. Observation. When a ship sails on several courses in 24 hours, the reducing of all these into one, and thereby finding the course and distance made good upon the whole, is com: monly called the resolving of a traverse. At sea, they com- monly begin each day's reckoning from the noon of that day, and from that time they set down all the different courses and distances sailed by the ship till noon next day, upon the log- board; then from these several courses and distances, - e e they compute the difference of latitude and departure for each course, by Case I, of Plane Sailing, and these, together with the courses and distances, are inserted in the Traverse Table, which consists of five columns; in the first are placed the courses and distances, in the two next, the differences of latil tude, north or south, belonging to these courses; and in the two last, the departures, east or West, belonging to these courses. Then the persons who keep these reckonings, sum up all the northings and all the southings, and taking the dif. ference of these, they know the difference of latitude made good by the ship in the last 24 hours, which will be north or south, according as the sum of the northings or southings is greatest. In the same manner, by taking the sum of aſ the Şastings, and likewise of all the westings, and subtracting the lesser of these from the greater, the difference will be the departure made good by the ship during the last 24 hours, which will be east or west, according as the sum of the eastings is greater or less than the sum of the westings; then from the difference of latitude and departure made good by the ship in the last 24 hours, found as above, they find the true course and distance made good upon the whole, (by Case 4, of Plane Sail- ing,) as also the course and distance to the intended port. Of Parallel Sailing. Since the parallels of latitude are con- centric circles to the axis of the earth, they always decrease the nearer they approach the pole; it is plain, therefore, that a degree of longitude on any of them must be less than its corresponding degree of longitude upon the equator. See the Table of DEG Rees of LoNG ITUD e. Now, to know the length of a degree on any of them, let P B, fig. 9, represent half the earth's axis; PA a quadrant of a meridian, and consequently A a point of the equator; C a point on the meridian, and C D a perpendicular from that point upon the axis, which plainly will be the sine of CP, the distance of that point from the pole, or the co-sine of C A its distance from the equator; and CD will be to A B as the sine of CP, or co-sine of CA, is to the radius. Again, if the qua- drant P A B is turned round upon the axis PB, it is plain the point A will describe the circumference of the equator whose radius is A B, and any other point C upon the meridian will describe the circumference of a parallel whose radius is CD. - Făg.7. .AW&zzz 36.3 tº A%, 5. Lºy, fo. E. § P (4. - $º A B § C D F § C D § -A B s C G D D Cor. 1. Hence (because the circumferences of circles are as their radii) the circumference of any parallel is to the cir- cumference of the equator, as the co-sine of its latitude is to radius. 2. And since the wholes are as their similar parts, the proportion will be, as the length of a degree on any paral- lel, is to the length of the degree upon the equator, so is the co-sine of the latitude of that parallel to radius. 3. Hence, also, as radius is to the co-sine of any latitude, so are the minutes of difference of longitude between two meridians, or their dis- tance in miles upon the equator, to the distance of these two meridians on the parallel in miles. 4. And, as the co-sine of any parallel, is to radius, so is the length of any arc on that parallel (intercepted between two meridians) in miles, to the length of a similar arc on the equator, or minutes of difference of longitude. 5. Also, as the co-sine of any one parallel, is to the co-sine of any other parallel, so is the length of any arc on the first in miles, to the length of the same arc on the other in miles. Af Of Mercator's Sailing.—Though the meridians all meet at the pole, and the parallels of latitude from the equator to the pole continually decrease, and that in proportion to the co-sines of their latitudes; yet in sea-charts the meridians are drawn pa- rallel to one another, and consequently the parallels of latitude made equal to the equator, and so a degree of longitude on any parallel is as large as a degree of longitude on the equator; also in these charts the degrees of latitude were still represent- ed (as they are in themselves) equal to each other, and to those of the equator. By these means the degrees of longitude being increased beyond their just proportion, and the more so the nearer they approach the pole, the degrees of latitude at the same time remaining the same, it is evident places marked down upon these charts with respect to their latitude and lon- gitude; and consequently their bearing from one another, must be very false. To remedy this inconvenience, so as still to keep the meridians parallel, we lengthen the degrees of latitude in the same proportion as those of longitude are, that the pro- portion in easting and westing may be the same with that of southing and northing, and consequently the bearings of places from one another are the same upon the chart as upon the globe itself. 708 ! N. A V N A W DICTIONARY of MECHANICAL sciFNGE. Let A B, fig. 10, be a quadrant bf a hieridian, A the pole, D, a point on the equator, A C half the axis, B any point upon the meridian, from which draw BF, perpendicular to A C, and B G perpendicular to C D ; then B G will be the sine, and BF br C G the co-sine of B D the latitude of the point B : draw D E the tangent and C E the secant of the arc CD. Then, since any arc of a parallel is to the like arc of the equator, as the co-sine of the latitude of that parallel is to radius. Thus any arc, as a minute on the parallel described by the point B, will be to a minute on the equator, as B F or C G is to CD ; but since the triangles C G B, CD E are similar, therefore C. G. will be to C D as C B is to C E, i. e. the co-sine of any parallel is to the radius, as the radius is to the secant of the latitude of that parallel. But the co-sine of any parallel is to radius, as the length of any arc (as a minute) on that parallel is to the length of the like arc on the equator: therefore the length of any arc (as a minute) on any parallel, is to the length of the like arc on the equator, , as radius is to the secant of the latitude of that parallel ; and so the length of any arc (as a minute) on the equator, is longer than the like are of any parallel in the same proportion as the secant of the latitude of that parallel is to radius. But, since in this projection the me- ridians are parallel, and consequently each parallel of latitude is equal in absolute length to the equator, it is plain the length of any arc (as a minute) on any parallel is increased beyond its just proportion, at such rate as the secant of the latitude of that parallel is greater than radius: and therefore to keep up the proportion of northing and southing to that of easting and west- ing, upon this chart, as it is actually upon the globe itself, the length of a minute, upon the meridian at any parallel, must also be increased beyond its just proportion at the same rate, i. e. as the secant of the latitude of that parallel is greater than radius. Thus, to find the length of a minute upon the meridian at the latitude of 75 deg. since a minute of a meridian is every where equal on the globe, and also equal to a minute of latitude upon the equator, let it be represented by unity, then making it as radius to the secant of 75 deg. so is unity to a fourth num- ber, which is 3,864 nearly ; and consequently, by whatever line you represent one minute on the equator of this chart, the length of one minute on the enlarged meridian at the latitude of 75 deg. or the distance between the parallel of 75 deg.00 min. and the parallel of 75 deg. 01 min. will be equal to three of these lines, and #6 of one of them. By making the same pro- portion, it will be found that the length of a minute on the meridian of this chart at the parallel of 60 deg. or the distance between the parallel of 60 deg. 00 min. and that of 60 deg. 01 min. is equal to two of these lines. After the same manner the length of a minute on the enlarged meridian may be found at any latitude ; and consequently beginning at the equator, and computing the length of every intermediate minute between that and any parallel, the sum of all these shall be the length of a meridian intercepted between the equator and that paral- lel; and the distance of each degree and minute of latitude from the equator upon the meridian of this chart, computed in minutes of the equator, forms what is commonly called a table of meridional parts, as is that given in our directions for the construction of Mercator's chart in the article MAPs. •. If the arc B D of the foregoing figure represents the latitude of any point B, then (CD being radius) C E will be the secant of that latitude ; but it has been shewn above, that radius is to secant of any latitude, as the length of a minute upon the equa- tor, is to the length of a minute on the meridian of this chart at that latitude ; therefore, C D is to C E, as the length of a minute on the equator is to the length of a minute upon the meridian at the latitude of the point B. Consequently if the radius CD is taken equal to the length of a minute upon the equator, C E, or the secant of the latitude will be equal to the length of a minute, upon the meridian of that latitude. Therefore, in general, if the length of a minute upon the equa- tor is made radius, the length of a minute upon the enlarged meridian will be every where equal to the secant of the arc contained between it and the equator. - Hence, since the length of every intermediate minute between the equator and any parallel is equal to the secant of the lati- tude, (the radius being equal to a minute upon the equator) the sum of all these lengths, or the distance of that parallel on the enlarged meridian from the equator, will be equal to the sum of all the secants to every minute contained between it and the equator. Consequently the distance between any two parallels on the same side of the equator, is equal to the dif. ference of the sums of all the secants contained between the equator and each parallel; and the distance between any two parallels on contrary sides of the equator, is equal to the amount of the sums of all the secants contained between the equator and each parallel. , Hence, by the tables of meridional parts may be constructed Mercator's nautical chart. - . In fig, 11. Let A and E represent two places upon Mercator's chart, A C the meridian of A, and C E the parallel of latitude passing through E; draw A E, and set off upon A C the length A B equal to the number of minutes contained in the difference of latitude between the two places, and taken from the same scale of equal parts by which the chart was constructed, or from the equator, or any graduated parallel of the chart, and through B draw B D parallel to CE, meeting A E in D. Then A C will be the enlarged difference of latitude, A B the proper difference of latitude, C E the difference of longitude, B D the departure, A E, the enlarged distance, and A D the proper distance between the two places A and E; also the angle #º will be the course, and A E the rhumb-line between them. - - - - * * - r Of Oblique Sailing.—The questions that may be proposed on oblique sailing are innumerable; we shall therefore select one as an example. Coasting along the shore, I saw a cape bear from N N E : then I stood NW b W 20 miles, and I observed the same cape bear from me N E b E: required the distance of the ship from the cape at each of those stations. . Geometrically.—Draw the circle NW E S fig. 17, to repre- sent the compass, N S the meridian, and W E the east and west Iine, and let C be the place of the ship in her first station; then from C set off upon the NW b W Fºyz7. line, C A 20 miles, and A will be the place of Bºgº the ship in her second station. From C draw pº >\{s, the N N E line C B, and from A draw AB -ºš Áº parallel to the N E b E line CD, which will meet § e C B in B, the place of the cape, and C B will be the distance of the ship from itin its first station, S and A B the distance in the second. The angle D C E is equal to the angle N C A, hence the parallelism of the lines D C, B.A. To find which by calculation:—In the triangle A B C are given A C, equal to 20 miles; the angle A C B equal to 78 deg. 45 min. the distance between the N N E and N W b W lines ; also the angle A B C equal to B C D equal to 33 deg. 45 min. the distance between the N N E and N E b E lines; and consequently the angle A, equal to 67 deg. 30 min. - - Hence, for C B, the distance of the cape from the ship in her first station, the proportion will be (by oblique trigonometry) S. A B C : A C : : S. B A C : C B. i.e. As the sine of the angle B . . . . . . . . . . . . . . 33° 34' 9-74473 is to the distance run A C . . . . . . . . . . . . . . . . . 20 — 1 "30163 so is the sine of B.A. C. . . . . . . . . . . . . . . . . . . . . 67 30 9.96562 to C B . . . . . . . . . . . . . .g. e. e. e. e º 'º e º ºs e e º & © & Q & © tº e s 33 26 1-52191 the distance of the cape from the ship at the first station. Then for AB it will be, (by oblique trigonometry,) S. A B C : A C :: S. A C B : A B i.e. As the sine of B . . . . . . . . . . . . . . . . . . . . . . 33° 45' 9"74474 is to AC ...............… º e º g tº ... 20 – 1:30163 so is the sine of C . . . . . . . . ... e. e. e. e. e. e º e s tº is a tº e º º 78 45 9°99157 to AB........... e e s is e º e º e º 'º º º * * * * * * * * * * 35°31 1-54.786 to the distance of the ship from the cape at her second station. Of the Log Line and Compass.-The method commonly made use of for measuring a ship's way at Sea, or how far she runs in a given space of time, is the log line and a half-minute glass. —See LOG. - • : Of the compass we may observe, that the meridian and prime vertical of any place cuts the horizon in four points, at 90 deg. N A W N A W 709 I).ICTIONARY OF MECHANICAL SCIENCE. €istance from one another, viz. north, south, east, and west: that part of the meridian which extends itself from the place to the north point of the horizon is called the north line; that which tends to the south point of the horizon is called the south line ; and that part of the prime vertical which extends towards the right hand of the observer when his face is turned to the north, is called the east line; and lastly, that part of the prime vertical which tends towards the left hand, is called the west line; the four points in which these lines meet the horizon are called the cardinal points. - - In order to determine the course of the wind, and to discover the various alterations or shiftings, each quadrant of the hori- zon, intercepted between the meridian and prime vertical, is usually divided into eight equal parts, and consequently the whole horizon into thirty-two; and the lines drawn from the place on which the observer stands, to the points of division in his horizon, are called rhumb-lines; the four principal of which are those described in the preceding paragraph, each of them having its name from the cardinal point in the horizon towards which it tends: the rest of the rhumb-lines have their names compounded of the principal lines on each side of them, 'as in the figure ; and over whichsoever of these lines the course of the wind is directed, that wind takes its name accord- ingly. See CoMPASs. - - Concerning Currents, and the method of making proper allow- ances for their effects upon a ship's way.—Currents are cer- tain settings of the stream, by which all bodies (as ships, &c.) moving therein, are compelled to alter their course or velocity, or both, and submit to the motion in pressed upon them by the current. The great and general currents are from east to west throughout the tropical regions, and from north to south towards the equator, coinciding with the regular tropical winds. Along the shores of continents and islands they are often diverted from their natural course, and being sometimes concentrated into a narrow channel, acquire an almost preter- natural velocity; as the great current from east to west along the American continent. See CURRENT. The northern seas are chiefly moved by the action of the polar current, extending along even the whole coast of Britain from the Orkneys south- ward. Case 1. If the current sets just the course of the ship, i.e. moves on the same rhumb with it; then the motion of the ship is increased, by as much as is the drift or velocity of the cur- rent. - Case 2. If the current sets directly against the ship's course, then the motion of the ship is lessened by as much as is the velocity of the current. - The method of keeping and correcting a journal at sea, by making proper allowances...for the lee way, variation, &c. — 1. Lee way is the angle that the rhumb-line, upon which the ship. endeavours to sail, makes with the rhumb she really sails upon. This is occasioned by the force of the wind or surge of the sea, when she lies to the windward, or is close-hauled, which causes her to fall off and glide sideways from the point of the compass she capes at. Let NESW represent the compass; and suppose a ship at C capes at, or endeavours to sail upon, the rhumb C a ; but by the force of the wind, and surge of the sea, she is obliged to fall off, and make her way good upon the rhumb C b; then the angle a C b is the lee way; and iſ that angle is equal to one point, the ship is said to make one point lee way ; and if equal to two points, the ship is said to make two points lee way. The quantity of this angle is very uncertain, because some ships, with the same quantity of sail, and with the same gale, will make more lee way than others. - To find the lee way.—Let the ship's wake be set by a compass in the poop, and the opposite rhumb is the true course made good by the ship; then the difference between this and the course given by the compass in the binnacle, is the lee way required. If the ship is within sight of land, then the lee way may be exactly found by observing a point on the land which continues to bear the same way; and the distance between the point of the compass it lies upon, and the point the ship capes at, will be the lee way. Having the course steered, and the lee way given, we may from thence find the true course thus: Let your face be turned directly to the windward; and if the ship has her larboard tacks on board, count the lee way from the course steered towards the right hand; but if the starboard tacks are on board, then count it from the course steered towards the left hand. Thus, suppose the wind at north, and the ship lies up within six points of the wind, with her larboard tacks on board, making one point lee way; here it is plain, that the course steered is ENE, and the true course E by N. ; also suppose the wind is at NNW, and the ship lies up within 64 points of the wind, with her starboard tack on board, mak- ing 13 point lee way, it is evident that the true course, in this case, is WSW. We have this general rule for finding the ship’s true course, having the course steered and the variation given, viz. let your face be turned towards the point of the compass upon which the ship is steered; and if the variation is easterly, count the quantity of it from the course steered towards the right hand; but if westerly, towards the left hand; and the course thus found is the true course steered. Suppose the course steered is N by E, and the variation one point easterly, then the true course steered will be NNE ; also suppose the course steered is NE by E, and the variation one point westerly, then in this case the true course will be NE, and so of others. Hence, by knowing the lee way, variation, and course steered, we may from thence find the ship's true course; but if there is a cur- rent under foot, then that must be tried, and proper allowances made for it. After making the proper allowances for finding the ship's true course, and making as just an estimate of the distance as we can ; yet by reason of the many accidents that attend a ship in a day’s sailing, the latitude by account fre- quently differs from the latitude by observation, and when that happens, there must be some error in the reckoning; to dis- cover which, and make its correction the reckoning, you may observe the following rules:—1st. If the ship sails near the meridian, or within 2 or 2% points thereof, then if the latitude by account disagrees with the latitude by observation, it is most likely that the error lies in the distance run; for it is plain, that in this case it will require a very sensible error in the course to make any considerable error in the difference of latitude, which cannot well happen if due care is taken at the helm, proper allowances are made for the lee way, variation, and currents. Consequently, if the course is pretty near the truth, and the error in the distance runs regularly through the whole, we may, from the latitude obtained by observation, correct the distance and departure by account, by the following analogies, viz. As the difference of latitude by account is to the true dif- ference of latitude, So is the departure by account to the true departure, And so is the direct distance by account to the true direct distance. If the courses are for the most part near the parallel of east and west, and the direct course is within 5% or 6 points of the meridian ; then if the latitude by account differs from the observed latitude, it is most probable that the error lies in the course or distance, or perhaps both. The form of the Log-book and Journal, together with an example of a day's work, are here subjoined. To express the days of the week, mariners commonly use the characters by which the sun and planets are expressed, viz. G) denotes Sunday, C Monday, 3 Tuesday, 3 Wednes- day, nº. Thursday, 2 Friday, 2 Saturday, called respectively Dies Solis, Dies Lunae, Dies Martii, Dies Mercurii, Dies Jovis, Dies Veneris, Dies Saturnii, From the following table it will be scen, that the ship by account, has come to the latitude of 47 deg. 46 min. north, and has differed her longitude 2 deg. 5 min. westerly ; so this day I have made my way good, south 31 deg. 31 min. west, distance 157.4 miles. At noon the Lizard bore from me north 31 deg. 31 min. east, distance 157.4 miles; and having observed the latitude, I found it agreed with the latitude by account. See LoNGI- TU D E. 8 S N A V N A v DictionARY of MECHANICAL scIENCE: The Form of the Log Book, with the Manner of working Days' - - Works at Sea. - - The Log gook. H |K # K|Courses. Winds. l, Observations and acci- dents. - - ( — day of — | 1 - Fair weather: at four 2| North. this afternoon I took my 3 departure from the Lizard – 'I - I - in the lat. of 5 deg. 00 min. 4 * * N. it bearing NNE, dis- 5 7 SW by S | N by E |tant 5 leagues. 6 7 7| 7 || 1 8|| 7 || 1 9 || 6 - 10 || 6 The gale increasing,and 11 || 6 SSW E by S being under all our sails. 12| 6 || 1 * ºsmºs **ass=s After three this morn- | | 6 || 1 ing, frequent showers, 2| 6 || 1 |SWbyW| NNE with thick weather till 3| 6 || | 1 Ilear nôOn. 4|| 7 5 l 6 7 s The variation I reckon 8| 8 SW EN E to be one point westerly, 9| 8 || 1 10 || 9 $ - 11| 8 || 1 |SW 3 WIN Eby E 12| S THE Log Book. Courses correct. Dist. |Diff. Lat. Diff. Long. N. S. E. W. SSW 50 462 || || 29.4 S by W 19 18°6 5'5 SW 49 29-7 45°5 SW by S 24'5 20-2 20-0 SW 3 S 25'5 19'5 19°5 144'2 125'0 Inland NAVIGATION, expresses more properly what relates to canals, rivers, and lakes, than the ordinary but well known word Canal. Egypt, the cradle of science, was the birth-place of the earliest canals, one of which, according to Herodotus, (lib. ii.) passed from the river Nile to the Red sea, and so vast || that four ships could pass abreast. Its navigation was per- formed in four days. Aristotle (Met, lib. i. cap. 14.) says, a king attempted to draw a canal from the Red sea to the Nile, but abandoned the work because the Red sea was higher than the land of Egypt. Diodorus Siculus (lib. ii.) makes it com- municate with the Pelusiac branch of the Nile. Strabo affirms, that in his time (lib. i. and xvii.) the merchants of Alexandria formed an outlet from the Nile in the Arabic gulf, to go on to India. It was, he adds, of 100 cubits breadth, and of depth sufficient for the largest vessels. Pliny says, (lib. xxvi, cap. 29 and 33) it began near Bubasto, and went to the Red sea. | The geographer Ptolemy calls it Trajan's river. During the glory, of the Mahomedan conquests, Amrow, who conquered Egypt about 635, opened this canal from the Nile to Quoizoum on the Red sea, to convey the contributions of corn into Arabia. Plkmain tells us that it was shut up again by the Caliph Alman- | the other. | vanishes, and the canal is cut entirely along the side of the hill, and only the lower bank is required to be made. zor in 773. China abounds in canals, yet India is devoid of such means of transporting the produce of its rich soil; Persia has no inland navigation worth mentioning; Greece and Italy are alike destitute of these moveable roads, which afford in Holland, France, and Britain, such facilities to commerce. The United States of America now begin to rival France in canals. The canals in England are both numerous and grand; but outdone, perhaps, by the Forth and Clyde canal, and cer- tainly by the Caledonian canal, which opens a communication between the Atlantic on the western coast of Scotland, and the German ocean, at the Murray Frith. The latter passes through Loch Ness, and allows vessels, drawing 18 feet water, to be tracted along. See the plan and details of this canal on the plate. But the canal in agitation to be cut between the Eng- lish Channel and the Severn, to open a communication across the country, without doubling the Land's End, will be the most advantageous work of the kind constructed in England. Theory of Canal Cutting.—It is evident, that in cutting canals, no farther excavation is required than that which will hold the water at the given depth and breadth; and since, according to the modern practice, a bank on either side is likewise made with the stuff excavated, it is evident, that if we make that bank of sufficient strength and closeness to con- tain the water, the level of the surface of the canal may be thereby raised above the natural surface of the land, and great part of the excavation saved. One of the first objects, there- fore, in canal cutting, is to know at what height above the surface of the land the canal may be carried on level ground, when the excavated stuff or cutting will just make the banks. This is called level cutting. When the ground along which the canal is carried has a declivity, the quantity of stuff to be applied to one bank is necessarily greater than that wanted for This disparity may increase until the one bank This is the simplest case of canal cutting, and the work admits of being laid out in a much more expeditious way than has commonly been employed, as will be seen: this case is called side cutting, or oblique cutting ; the slope of the cut which is made in the hill being made the same as the exterior of the canal bank. These two lines in the section are parallel to each other; and there is a certain point in the section, through which, if any line be drawn, representing the surface of the ground in any case, which line we shall call the line of cutting, the portion of the section thereby exhibited as excavation, will always be equal to that exhibited as embankment. We shall call this point the centre of cutting. PRoblem I.-Given the outline section or profile of a canal in sidelong ground, with parallel slopes. To find the centre | of cutting. Case 1. For one bank only. See plate I. CANALs, fig. 1. Given A B C D a section of the canal, CD E G F, a section of the bank. To find the centre of cutting. Produce the lines B C and E D to G and A. Draw the per- pendiculars C m, Dºn, and the diagonals A.G., m n intersecting in p. Through p draw the parallel sp tº and bisectit in of ois the centre of cutting, through which, if any line Ho F be drawn cutting the slopes A B and E G produced, the section H B C w will always be equal to w DE F. . The centre of cutting is also the centre of cut and cover, for Ho is always equal to o F. Hence, if a line be staked out along the ground at the level of the centre of cutting, it will exhibit the middle of the ground wanted for the use of the canal, whatever may be the inclination of the surface, at least if that inclination be regular as far as the breadth required; and the distance o H or o F, on each side of the centre, may easily be found by a line drawn across the section with the given inclination of the ground. The distance of the centre of cutting, from the centre of the canal at surface water, is equal to w q + D E. Hence, if the line of the middle of the cut and cover be laid out, or the centre of cutting, we may lay out a set of stakes at a certain horizon- tal distance therefrom ; and the top of these stakes being made even with the level of surface water, they will exhibit the line of the middle of the canal when finished. - " ... • At half the general breadth A E, from the centre of cutting, INLAND NAVIG AT I on. THE THE ory & PRAczzcz of Czyz TryG CAAALs. * * * * * * - * ~ * * * * * * - **. * * * * * * **. **. * * **. * ~. * * ** * * * * - * *~. - * , **. - ** ***. *s *~. **, - * * r - ** *** w º - * * - - **, ** -. * * * **-- - - - **. *R. **. **. * * * * *s ** Fſ. Fig. 2. T--~~ Prob. Z. Caye 2. %—º. alº--- ST: .** •., A.N.--—- ~. \ . \; .." 2 * • .* `--, T- > : ...’ * - *s, o, S - “, .** * º - E. IE F FL I A. 3. TZ. 2TS Pro T. * . . - 2" N # C ID G. N. WORKING SECTION OF CUTTING FOR A CANAL. l 2 - - 32 Zºº &zeadž at £oz'. Fig. 7. Wazer raz72ce 26 ºf Centre of & Zevel. E777; - - - Zomºny zaº . : - SIE CTION OF THE CALEIDONIAN CANAL . .” sy—z-z-z- s\ ... -- Shewing the practice of cutting. - \. 2é28% of the Centre *...ºf..&s § Tior. Sº 8. sº ‘S S i is is § s | - Azºre, re' . 22 zº . . Bozzozzz. 60 fººlpazer – NAVIGATION, IN L, ANL). THE THEORY & PRA CTICE of Loºs, G4TE.S. &c. º Fig. - . º - | THE HHH! H lif - - Fig. 3. Circular Lock at Agde. ag-º º ºse tº 3° tº 72 se º zºeae º zºet. ig. 6. Cairºposas CANAL. © C. | | | | | | | | | | || BASIN OF THE LOCK. 170 feet of Zayd and terret hºle. THE Lock. Gates of the Caledonian Canal. - Fig. 7 ºper. - Tº is º º -> º Murray * º, Errth of - - --~"- º - *. - Firth F-º- - º ! * S - - c- - - ºublished by ºr sºn & Cº. Lºndºn lºº. -- N A W JN A W 711 DICTIONARY OF MECHANICAL SCIENCE: * and on that level, is a point in the exterior slope of the bank, and a line of stakes may be set out at that distance and level, which will direct the wheeling of stuff for the formation of the bank. And at these stakes a level and plumb line may be applied, with the slope of the bank, by which the point F, where the exterior slope of the bank meets the surface of the land, will be found, and may be marked out, and the edge of excavation will be at an equal distance on the other side of the centre of cutting. At the same distance, viz, half the general breadth A E, and on the upper side of the centre of cutting, at its level is the points, in the inner slope of the excavation. The horizontal distance ov, of the inner slope of the bank from the centre o, will be found by saying B n : n C :: 2 o : o v; a line of stakes may therefore be placed at this distance and level, to direct the wheeling as above, and by a level and plumb, the commencement of the bank and excavation may be marked in the same way. The quantity of excavation above the level of the centre of cutting is the triangle os H, and the base os will always be proportional to the height Hy of the upper edge above the level. The quantity of excavation below the level of the centre of cutting, differing from s B C v only by the small triangle o w v, of which the base o v being constant, the area is proportioned to the perpendicular from w to the level of the centre of the cutting. Case 2, fig. 2. When there is a towing path on the upper side, given a A B C D E G, as before, the profile of the path, canal, and bank, take D d – a A, draw a b and c d parallel to the slopes, thereby converting the section a A, B C D E into a bed E, in which the towing path is supposed to be added to the bank; proceed to draw the lines a G, c d, and st; the middle o will be the centre of cutting. PRobleM II.-Fig. 3. To reduce the section A B C D EF with a second bench or path EF, to the equivalent section A B I KF, with one bank only, but wider and shallower, the banking cut down and filled into the bottom. Produce B C and H F to Z, also C D to G ; make D N = D G. Draw the parallel N L (or, if the slopes are all equal, make D L perpendicular to G C,) on FL, describe the semi- circle LM F, cutting the perpendicular G. M.; make ZK (and , ZI) equal to Z M ; draw the parallel KI, and it is done. The height of IK over C G is nearly found by the slopes. PRob LEM III.—Fig. 4. Given the profile of a canal with two banks, the slopes being all equal. level cutting. Reduce the section A B C D into A H K E. For this find o, the centre of cutting. the perpendiculars VN, O N ; with centre N and radius NV cut E A in p ; draw M L the line of level cutting. PROBleM IV.-Fig. 5. Given as in last problem. To find any line of oblique cutting. Find the line of level cutting. Produce the slopes to meetin V. Draw the perpendicular VI; from L draw L N with the given slope of the ground, cutting VI in N, making N p and p Q = VI, also W R = p I. Through R draw K R H for the line of oblique cutting required, If the slopes are parallel, then N R = N I, and I is the centre of cutting. The centre cutting over level cutting, in this case of oblique shallow cutting, is the difference between oz y and C £ 10. - PROBleM W.-Fig. 6. Given the profile of a canal, as in last case, and the line of ground level too low for level cutting. Required to widen the canal so as to have cutting for the banks. z It is obvious, that the trapezoid O. M. must be provided for by the parallelogram D Q, wherefore draw the perpendiculars MN, D p, and make D p = . PQ; D G is the additional width, or C G is the mean bottom. Or, by calculation, as N T : T 0, so p D = R s : D C. TO is formed from L M by adding the slope base for the height MT at each end, and is usually L M + 3 MT, or 3 R. S. A similar problem to the above may be given for narrowing the canal in deep cutting.; but this is of less use ; and it is evident, that when the ground OK is at or below the bottom ... * To find the lines of Produce each slope to meet in V; draw make V a = P Q, and through a parallel to E A = R. S. Draw the parallels O N and C D, the problem is impossible, and the case becomes one of embankment. $ºr t Examples. Fig. 7. Given a canal of 14 feet bottom, 26 feet water surface, the banks rising two feet over water, and 10 feet broad at top, slopes being 13 to 1, required the centre of cutting: 26 6 total depth. 6 E 2 × 3 1; 32 breadth at top. 9 inner slope. 10 10 top bank. 42 10 6 42) 60( = 1; feet, the height of the centre 42 of cutting over the bot- º-s, tom of the canal. 18 — - 3 — ºf 42 42 . . . . . . g a = 21 feet, is its distance from the inner slope of the upper, and from the outer slope of the lower side. From 6 deduct 13, and there will remain 44, which multiplied by 13 will give 63, to which add 5 the half breadth of top bank, and the sum 11% is the distance from the middle of the canal. 13 × 3 = 4; 14 bottom. 18} breadth of canal at level of centre. 21 half total breadth ditto. 2} distance of centre from outer slope of the canal; and it is evident, that the centre of cutting is in the bank in this case. Evample. Fig. 8. The Caledonian Canal has 50 feet bot- tom, and 20 feet water : the slopes are 13 to 1, to within two feet of surface water, where there is a bench or retreat of five feet; above this the banks rise five feet with a slope of two to one, and are 18 feet wide at top. On the upper side, in side- cutting, there is a bench or towing path of 10 feet. The area of the part on each side over the bench or retreat, if the inner slope was carried to the top, would be, 5 - 4. e (5 + 73) × 3 = 31}, and the breadth at top is 7% feet. 31} 62; ~ 23 So that the space contained over these benches is equivalent to widening the canal 23. The depth 23 × 13 = 34}, is the base of the inner slope if produced to the level of the top of the banks; whence 50 + 2 × 34} = 119, would in that case be the width of the canal. Also, 18 + 7% = 25% would be the breadth at top of the bank, and 10 + 7} = 173 would be the breadth of the upper bank; their sum, 43 feet, must be diminished by 23, and the width of canal increased by the same quantity, to allow for the recesses at top. Then say, as total width 119 + 43 – 162 canal and banks to 43 — 23; + 34} = 74; top bank and one slope. So depth of canal 23. To depth below centre of cut- ting 10}, and consequently, the depth of said centre from the top, is 23 — 10% = 12#. Of the Form of Locks.-The most natural form of the lock is that which approaches, as nearly as possible, to the figure of the boats which are to use it. The width must be only a little more than that of the boat, and it must be the same throughout, as the boat has to pass along the whole lock; and the length may only exceed that of the boat by a space sufficient to admit of working the gates. A long rectangle is therefore the natu- ral figure. It consumes the smallest quantity of water in pass- ing the boat; is filled and emptied in the shortest time; and, on the whole, is constructed at less expense than any other form. See fig. 5, Caledonian Canal. Having thus determined the preference to be given to locks of a rectangular form to those of a circular form, as in the canal of Languedoc, or the circular lock at Agde, figs. 1 and 3, our next object is to consider their length and = 2%. 712 N A V 'N A V DictionARY of MechANICAL science. breadth. This must depend on the size of the vessels for which the locks are intended. When the vessels are to be navigated also on rivers or the sea, the breadth of the locks must be more considerable than where canal boats are intended to pass; for in rivers the shallow water frequently met with, obliges us to give the vessel an excess of breadth, so that her draft may be diminished as much as possible ; whereas, in canals, we are masters of the depth of water, and find it more economical to restrict the breadth as much as possible, as we thereby dimi- nish the evaporation, the expense of cutting, and the purchase of property. Dr. Anderson, and other writers on the subject of small canals, have not attended sufficiently to this matter, when they recommended widening the surface only of small canals in order to give a greater facility of trackage. In our English canals, the usual size of boats supposed fit for the navigation of rivers and canals alternately, is one of 14 feet beam. Where the canals are intended also to be used by coasters, greater widths are adopted. Thus the Forth and Clyde Canal admits vessels of 19 feet beam; and the Caledo- nian canal, which is a canal of transit for sea-going ships, ad- mits vessels of 39 feet wide; but in the great majority of canal navigations in England, a much smaller width has been adopt- ed. Seven feet beam has been the usual size in the central canals, and still narrower boats have been proposed; but they become liable to many inconveniencies, and can only be em- ployed in the transport of very heavy substances, such as ores or minerals. The narrow boat has the advantage of being navigated with more ease, and of causing less expense in lock- gates, bridges, &c. - Length and Breadth of Locks.—The length and breadth of lock chambers ought to be necessarily regulated by the form of the boats that are to pass upon the canals. It is common to make this kind of boats longer and narrower than those of rivers, which, on account of the small depth of water found in some places, are obliged to be made as flat as possible. In canals, on the contrary, we are able to give a considerable depth to the water, but we do not give them great breadth, so that there may be less evaporation, less earth to be removed, and less ground to be occupied. There is commonly no more breadth given to canals than what is necessary for enabling two boats to navigate with ease beside each other, and even in the diſficult parts, such as those which are cut in rock, there is often no more breadth given than what is necessary to pass a single boat, only some places are made wider, at which one boat may lie by, while another one passes in an opposite direc- tion. Besides, a principal object in making use of narrow boats on navigable canals, is to diminish the breadth of the lock-gates, which wear longer, and are more easily worked, than when they are broad. Narrow boats are also more easily drawn than those which are wider and shorter. But what ought principally to regulate the width and breadth of locks are the dimensions of those in the canals already executed, and through which the boats of the new canal may have to pass. i Coehorn, in his fortification, has given a very ingenious con- struction for a retaining wall. His designs were intended for the soil of Holland, where stone is not to be found, and it be- hoved him to be as sparing of masonry as possible. His wall is only three feet thick, battering considerably in front, and leaning nearly as much behind, supported by long and thin counterforts, which are connected together by two rows of arches, one over the other'; and also by two walls arched hori- zontally against the earth. The intervening spaces are filled with gravel and splinters for the purposes of defence, which is also the reason of his counterforts being made so long, and connected by double walls. Coehorn does not give this as his own invention, though he describes it very carefully, but as hav- jing been adopted by him from some older German authors. Gauthey, a civil engineer in the French service, who con- V structed the canal of Charolois, or of the Centre, about thirty V years ago, has published a very sensible paper on the subject of walls, in the Memoirs of the Academy of Dijon. . After criti- cising the theories of Couplet and others, given in the Trans- actions of the Academy of Paris, and the profiles of Belidor and Vauban, he proceeds to shew, by experiments made with sand and shot against a smooth plane, that the pressure acts at the centre of gravity, or one-third of the height of the Wall, of the sides. cal phrase. and is the same whatever be the slope; that in a plumb wall, if the height of the wall be three times the acting power of the earth, and base 4ths of the height, there is an equilibrium against oversetting. The acting power in practice is one fourth of the weight of the triangle of the earth, with a slope of 45°, or one-half of the square of the wall. . He then shews, that retreats on the back of the wall may be made, so as to take off all acting power, and that a wall of 2 feet thick, and 30 high, battering k, with counterforts of 3 by 4, and 18 asunder, joined by two arches of 2 ft. thick, is abundantly strong. Such a wall he employed with success for one of the quays of the Saone ; and it is evident, that the saving of masonry compared with the common construction is immense. But in the walls of locks more must be attended to than the pressure of the earth alone. A film of water inserted between the back of the wall and the earth, will act hydrostatically against each of them, will counteract the aid which might be derived from friction, and if the lock be emptied in that state, may overset the wall inwards. But the hydrostatical pressure of the water within the lock can hardly do any harm, seeing the motion of the wall must be prevented by the resistance of the earth behind ; hence, the utility of counterforts behind the wall, is mainly that of cutting off the communication between one portion of such a film of water and another, so that the action being confined to a smaller space is the less dangerous, as the wall also derives a kind of abutment from the counter- forts. The upper part of the lock-wall, so far as the water rises and falls thereon, is (unless water be very abundant) usually made perpendicular, its thickness therefore must be So calculated as to resist the pressure of water of equal depth, and, taking the specific gravity of stone as 23 times that of water, this thickness will be the depth multiplied into 0°365, or a little more than }, and one half the depth will be sufficiently ample in any case. The lower portion of the lock may be suited to the shape of the vessels which navigate through it, and therefore it will per- mit the wall to be made with a considerable batter, or slope to the front, by which means the point of conversion being farther removed from the centre of gravity of the wall, the stability will be considerably increased without an increase of materials; but it must be observed, that the point of conversion itself must be sufficiently secured. To prevent sliding, it ought to be in- serted some way into the ground of the foundation. If built upon a timber platform, it ought to be provided with an abut- ment; and if upon piles, they ought to be driven in the direc- tion of the thrust, which will be nearly that of the face of the wall. Now, as the opposite wall of the lock requires the same precautions, and its action is directly in face of the other, by joining the bottom of the walls by an inverted arch, we not only destroy the horizontal thrust, but also extend the foun- dation, which, in the case of soft ground, becomes of great im- portance. The inverted arch has been much employed in this situation by our late British engineers. On the Continent, we believe it is still the practice to rely on a platform of timber, or even a simple flat pavement, especially where the ground is firm. See the figures of the locks for the Canal of Burgundy, figs. 1 and 3 of the Plate. - In the timber countries, as Russia, America, and even Holland, where stone is scarce, there are locks of which not only the floor but even the sides are constructed of wood. In such cases, the thrust of the opposite sides are sometimes made to balance each other by cross pieces over the lock, placed between the upright posts which support the planking Instances of this may be seen on the river Lea, but the practice is not certainly to be recommended. This will tend to float the lock upwards like a ship, and unless the weight of the side-walls be sufficient to counteract this, the bottom or floor will give way, or be blown up, as is the techni- The floatation of a timber floor will aid this ope- ration, while the weight of an inverted arch will to a certain extent resist it. This forms one of the greatest objections to timber locks, and in them it is perhaps advisable that the dams of sheet piles should not be brought below the upper gates; but as all locks must at times be emptied for the purpose of repairs, &c. we have still the head of water of the lower pond, or ordinary depth of navigable water, to be resisted. The floor N A V N A W DICTIONARY OF MECHANICAL SCIENCE. 713 ºtherefore must be carried a considerable way into the land, and thereby loaded by the adjoining earth; or, if built within a river, it must be kept down with stones, &c. laid over the cross beams projecting on each side. This is the construction of a lock on the Witigra canal. Or the floor and sides may be bolted to piles driven as firm as possible into the bottom, thereby as it were mailing the lock to the ground. The float- ation of the lock and weight of the side-walls will counterba- lance, each other when the section of the masonry in the walls and bottom is two-thirds the area of the open space of the lock. Plate II. fig. 10. The average thickness of the walls, therefore, where there is no invert, would require to be one-third of the width of the lock. Where there is an invert, the thickness will be much less, but may be readily found from the above. Brick walls would of course require a greater thickness than those of stone; and here we may perceive the importance of those means by which the weight of the adjacent earth is made to rest upon the back of the wall, for we thereby obtain an addi- tional counterpoise against the floatation without expense. Puddling behind the walls is therefore resorted to with great propriety. See fig. 11, Plate II. - It is needless in this place to be more minute in the calcu- lation for the thickness of the walls; the principle may be easily understood and applied when wanted. Besides, with respect to locks, it is rather an extreme case, as they are rarely expos- ed to greater differences of pressure than the ordinary rise of the navigation. For tide-locks, and graving-docks, however, it is of high importance to guard against the hydrostatic pres- sure on the bottom ; and serious accidents have taken place where it has not been sufficiently attended to. We proceed therefore with the practical construction of the lock itself. The site and dimensions of the lock being determined, the first ob- ject is the excavation of the lock-pit, or place for the foundation. In small canals and navigations carried above the level of the neighbouring valleys, this is seldom attended with any difficul- ty, the excavation being in most cases level free for drainage; but in great locks connected with rivers, lakes, or the sea, it is often necessary to go to a considerable expense; and in many cases, all the resources of hydraulic engineering are re- quired to keep the excavation clear of water, or, when that is impracticable, to make a foundation independent of it. The varieties of soil and situation render it impossible, in such a work as this, to give general rules for proceeding in all CaSCS. the article Bridge, which will, we believe, be most useful for the young engineer, even in constructing canals. Several good examples of lock making, that occurred in the construction of the Caledonian Canal, shall now he produced. - Caledonian Canal.—Locks,—The Caledonian Canal is not only constructed on an unusually large scale, but, in consequence of various localities in the situation of its works, it affords much practical information to the civil engineer. Some of the most important instances are in regard to the sea-lock at each extre- mity of the navigation ; also that which is placed at the upper or south-western end of Loch Ness at Fort Augustus. With regard to the lock at the north-east extremity.—The shore of Loch Beauly, where the canal was to be connected with the tideway at Clachnacarry, near Inverness, being very flat, it was necessary to carry the canal, by artificial embank- ments, above 400 yards from high water mark into the sea, in order to obtain 20 feet of water upon and without the lock sills, at high water of meap tides. But this shore consisting of soft mud, into which an iron rod was easily pressed to the depth of 55 feet, it became doubtful whether a sufficiently substantial. cofferdam could be constructed of timber, and also if any plat- form could be made equal to support the weight of masonry unavoidable in a lock of 180 feet in length, 40 feet in clear width, having 20 feet of water, besides a rise of 8 feet. Upon duly considering all the circumstances, a new mode occurred to the conductors of that work, and that was, by uniting the two earthen banks which were projected from the shore, at the place where the site of the lock was fixed, so as to form a solid mound over all the space which the lock would occupy; and this was done for the purpose of squeezing out the water and consolidating the mud, by laying on a greater weight than the masonry of the lock: this was accordingly carried into effect. s We have already given some general principles under By the latter end of the year 1809, the mound was carried out to the necessary length, breadth, and height, and during its con- struction had sunk about 11 feet. A great quantity of stone was then laid upon the space the lock was to occupy, and levels taken to ascertain the precise height of the banks; in this state matters were suffered to remain for about six months, until August 1810, when, having found that no farther sinking had taken place, the excavation for the lock-pit was commenced in the before mentioned artificial mound; a chain-pump, worked by six horses, kept the pit dry when sunk to 15 feet in depth. At that time a steam-engine, of nine-horse power, was erected, by which the water was commanded, and the excavation of the lock-pit was completed in June 1811. Before getting down, to about 30 feet below the level of high water ordinary springs, it was necessary to penetrate into the compressed mud about 8 feet, and the small portions of water which filtrated through the surrounding mounds of earth (in which puddle walls had been carried up) was conducted in small gutters along the top of the compressed mud to the pump-well. As soon as the lock- pit had been excavated, rubble masonry, with lime mortar, was laid about two feet in thickness in the middle of the lock- chamber, and increasing to about 5 feet at each side; upon this the side-walls were founded, and brought up to the level of the top of the compressed mud, and then the inverted arch of squared masonry was put in, and the side-walls, counterforts, recesses, and wings, carried regularly up ; the masonry of the bottom part was carried on by short lengths of about 6 yards at one time, in order to prevent the compressed mud again softening and being squeezed together in the open space. The above mentioned mud was found to be readily penetrated by piles, but when these were suffered to remain a few hours, no power could move them. The masonry of the lock was very successfully completed in August, 1812; the gates were after- wards put up, and the lock has been worked for several years. The whole is now in a very perfect state. Corpach Lock.-The circumstances under which the lock at the south-western end of this navigation was constructed, differ greatly from what we have just described. It was found ne- cessary to connect the canal with the tide-way in Loch Eil, at Corpach, on the north-west side of the rock, situated about 100 yards from high water; this rock was covered at three-fourths flood ; and the lock was to be advanced so far into the sea, as to admit of the sill being laid upon the rock, where there should be 30 feet of water upon it at high water neap tides. For this purpose, water-tight mounds, faced with stone, were carried from the shore to beyond the extremity of the lock site. Be- tween the extremity of these mounds, a wooden cofferdam was constructed. The clearing away the gravel, Sand, and mud, the fixing the main piles firmly in the rock, and placing the wooden frames correctly in their proper places, were ope- rations of considerable difficulty ; but the success which attended a work of this magnitude and exposure, renders this mode deserving the attention of persons engaged in similar, or even inferior undertakings. Under the article BRIDGE foun- dations, we have minutely detailed every step of the process, and it would be an unnecessary repetition to introduce the de- scription here; we therefore presume it will be sufficiently satis- factory to refer to that article. Only, it may be farther observ- ed, that when the water had been excluded, and the rock exca- wated, no inverted arch was necessary. .. Fort Augustus Lock.-The ground upon which the five con: nected locks at Fort Augustus were to be placed, consisting of coarse open gravel, and the lowermost of these requiring to be constructed so as to admit 20 feet of water upon the lower gate-sills at the lowest state of the water in Loch Ness ; and the large river Oich, running upon the same sort of gravel, and close along the site of the lock, rendered it an arduous task to keep very large lock-pits clear of water ; for the rise of these locks being only 8 feet, the foundations of the second and third locks were also considerably incommoded by Water. This site for these locks being by much the most eligible for the navigation, it was absolutely necessary to endeavour to surmount these natural obstacles. The first step was, in 1814, to turn the whole of the river Oich to the northernmost side of a small island, and occupy part of the south channel by the locks. A trial-pit was next to be sunk; and, by means of a T 714 N A V N A V Diction ARY of MECHANICAL science. small steam-engine, of about six horse-power, it was earried to the depth of 18 feet; but here the water overpowered it. “A pump-well was then begun, and an engine of 36 horse-power, which had previously been provided, was erected. It com- menced.working in August, 1816, and the excavation of the lock-pit was carried on with all possible energy. It was con- .tinued, as long as the flood-waters of the Oich would permit— was againscommenced as soon as the state of the river would admit, in 1817, and, during that summer and autumn, the whole masonry of the lock, bottom, and wings, and the forebay, were: got in; but, in order to command: the water effectually, the engineer had, during that time, caused to be erected a third engine, of about nine horse-power, which happened also to be in readiness; and when the excavation was upwards of 25 feet. below the surface of Loch Ness, and the whole of the gravel still coarse and open, the power of all the three engines was required. These lock-pits being sunk directly into a mass of gravel, no cofferdam could be of any service. Under the in- verted arch and side walls of the lock, chamber, &c. rubble masonry, of a sufficient thickness was constructed; but it was here laid upon, and mixed with, abundance of moss, and this was done in order to prevent any shifting sand from perco- lating. At the latter end of the working season of 1818, the whole masonry of the lowermost lock had been built, also the inverted arch, and 14 feet in height of the side walls of the second-lock; and likewise the inverted arch, and 6 feet of the walls of the third lock; so that, except. for the purpose of putting up the gates, there could be no farther occa- sion for employing the steam-engines at Fort Augustus, and every risk was at an end. In these three locks, there has, itherefore, been afforded, cases of soft mud, hard rock, and very loose gravel, as foundations for very large locks. their form and dimensions, see Plate II. figs. 5, 10, and 11. described in this place. They are sawn out of a thickness proportional to the strain they are intended to bear. The points are gradually sharpened, so as to have a bevel or chamfer to one side only, so that in driving, each may be forced close against the preceding one ; still farther to secure the seam or joint against the transpiration of water, it is not un- common to groove the piles on one edge, and make a ridge or feather on the other to fit these grooves, so that the piles are, in driving, preserved in the same plane. Lastly, to save timber, the pile is frequently grooved on each side, and a slip or feather, which may be of harder wood, driven in between, so as to enter both grooves. The plank piles are preserved in position, by being spiked to sills, or horizontal beams of timber, extending in the line of the pro- posed sheet plank piling, and fastened to stout upright piles of baulk, placed at certain distances in the same line, called gauge piles. In the construction of a lock, one of the earliest objects of attention is the platform on which the gates are to traverse. It is usually formed of timber. A stout floor of plank is spiked or tree-mailed down upon sills, or transverse beams, which are laid across the lock, and their extremities built into the walls. The scantling of the sills and plank are proportioned to the fatigue they have to undergo. In great locks, there are usually two rows of whole baulk in thickness, laid close together over the whole floor, carefully bedded in a mass of water-tight rubble masonry; and, when the foundation is doubtful, longitudinal ground sills are laid below, then resting, if need be, on piles driven to a proper depth. A row of grooved sheet piles is driven across the lock at the upper and lower end of this plat- form, and the floor is carefully caulked to prevent any transpi- ration of water. On this platform the sill of the lower gates is placed ; its con- struction is that of tie beam and two rafters, having the angle or curve of the lock gates; and as it has the thrust of the water to withstand, care must be taken to give it sufficient abutment. The platform of the upper gates is constructed in all respects similar to the lower. The sheet piling at the lower side is un- necessary ; but care must be taken that the breast-wall or step of the lock be made water-tight, and carefully puddled upon the upper side. To prevent also its receiving any derange- For | break its progressive force as much as possible. The paddle The sheet piles; or plank piles heretofore alluded to, being of frequent use in hydraulic architecture, may be as well ment from the blows of boats, &c...it is necessaryºtößlay a wooden curb along the coping of this breast-wall. . . . ... In Ireland, timber has been sparingly used in the construc- tion of locks; good stone and mortar, are; in general, easily procured there. The platform for the gates is made of hewn stone. The sillis of hewn stone, set on edge, and usually two feet deep, supported on the lower side by a horizontal arch, which, at the upper gates, forms the coping of the breast of the loek; and; to resist blows from vessels, the key-stone of this arch is supported by two struts of horizontal flagging passing to the sides of the lock, or by a counter arch in the hewn-pave- ment of the platform. . In constructing the sidewalls, a recess is made on each side, to permit the gates to fall back out of the way of vessels; and it is not uncommon to make those for the upper gates act as waste- weirs or overfalls, to discharge the superfluous water of the canal into the paddle holes. These paddle holes are conduits of stone or brick, usually of a circular form, and about 18-inches diameter, by which the water of the upper level is conveyed into the lock chamber. From the lock it is usually conveyed into the lower level through sluices or paddles formed in the gates, below the level of the lower water;' but, in the upper gates, this is seldom practicable, for the breast of the lock being commonly higher than the lower level, a cascade would thereby be formed in the lock, which would be troublesome or danger- ous to the vessels. v. The conduits or paddle holes from each side are sometimes united at the back of the breast-wall, and discharge themselves through that into the lock. At other times they enter the lock separately in each side. In either case, the low level is pre- served back to the place of entry; and º is then per- mitted to fall down on a flat surface in the conduit, so as to \ itself is usually a square of cross planked wood, sliding up and down in a rabbeted:frame of timber, fixed in the stone month of the conduit or paddle hole. The lateral, pressure of the water makes it adhere closely to the frame, so that it is neces- sary not only to make it run with the grain of the wood, but also to have a considerable power to move it. This is done by a crank and pinion, working into a toothed rack) which is fixed on a bar or handle, rising from the paddle up to the top of the bank or gate. Sometimes screws are used instead of rack and pinion, and various other ingenious contrivances have been proposed, so as to make the paddle turn on an axis, either in its own plane, or at right angles thereto, like scouring gates, &c. One of the simplest modes we have seen of getting rid of the hydrostatic pressure and friction was proposed by Mr. John Duncombe, viz. to make the entrance or mouth of the paddle hole a horizontal circular opening, and -stop it by an open cylinder ground to fit it, and rising of the same diameter to the surface, where it could be lifted by a lever or other means, like the waste pipe employed in some cisterns. The waste water of the canal would of course escape over the upper lip of the cylinder, and pass along the paddle holes as usual. Such a cylinder may be made of wood or iron. The hollow quoins are upright circular grooves wrought in the side walls at the extremities of the sills; they serve as a hinge-place for the gate, the upright post of which that turns in them is named the heel of the gate; the opposite posts which abut against each other are called the head-posts. The heel-posts are retained in their places by a pivot or gudgeon at bottom, turning in a cup set in the stone, and sometimes the reverse, the cup being set in the heel-post. The upper part of the post is embraced by an iron strap or collar, which is carried back some way into the side wall, and firmly secured. The hollow quoins are commonly cut out of large scantlings of stone, or brick is moulded for the purpose, and cast-iron has also been employed on the Caledonian canal. The exterior portion of the lock above the upper and below the lower gates, are named the forebay and tailbay of the lock. The side walls are then made to splay away outwards to the usual breadth of the canal, so as to facilitate the entrance of vessels, and still farther to guide them; there are not unfrequently fender- beams, supported on piles, continued to some distance above and below the lock, and running into the bank on either side. '. , Strapping-posts are also used to check the way of the boats N A. V. N A W 715 DICTIONARY OF MECHANICAL scIENCE. in entering the lock; and; in the passage-boats on the canals in Ireland, a broad-shield of iron is placed on each side of the stem, and dropped under the quarter when the boat approaches a lock. It is readily hauled up again when the boat gets under way. . It is the invention of Mr. Sisson Darling, late secretary to: the Grand canal. - *Lock-gates are:framed usually of timber, though iron is also used in some of the small canals in England, and has lately been introduced in framing the large gates for the Caledonian canal. The head and heel-posts are connected by cross-beams or rails turned therein; the upper and lower bars are firmly attached by straps and bolts, and the whole planked over, usually in an oblique direction, by way of giving an additional stay to the framing. The head-posts must be brought truly to the angle of abutment. If of iron, they have a ribband of timber bolted thereon, to soften the blows they receive. The heels must be wrought to a circular form to fit the hollow quoin, into which the pressure of the water will force them home. The upper bar of the gate, in small canals, is usually continued a considerable way beyond the heel-post, and left as heavy as possible, or is loaded so as to form a counterpoise to the weight of the gate, and a lever for opening it. In great locks, capstans are employed to work chains, leading to the middle of the head-post on either side. Various other con- trivances have been adopted for opening and shutting the gates of large locks. In Holland, a boom or spar is commonly attached to the head-post, and brought over a windlass on the lock-wall, a little above the gate; a rope is made fast to the end of the spar, and taking two or three turns on the windlass, the spar end is carried to the other end of the spar, which thus, by means of the windlass, is made either to open or shut the gate. At Antwerp, the French have employed a rack-bar of wrought iron nearly in the same way. These heavy gates have usually a roller or truck-wheel placed under the foot of the head-post, and running on a quadrantal railway of iron, to facilitate their motion. With the same view, also, attempts have been made to give floatation to heavy gates. In Sweden, some gates were made for the dock of Carlscrona, which were to sink into a deep recess, and rise when wanted by the ad- mission of, and again pumping out of, a quantity of water, on the principle of the machine called the camel. At the dock of Monnikendam is the best, and we believe the oldest, boat-gate now in use. It has three parallel keels, which fit into grooves in the side walls, and, by admitting water, and extracting it again, it is made to sit down in its place, or float up so as to be removed when necessary; but though such vessels are peculiarly useful as stop-gates, or for docks, they are not well adapted to a constant or much frequented navigation. Reservoirs.—The mode of supplying a canal plentifully with water, being essential to its prosperity, it generally employs the attention of the engineer, previous to determining the most advisable line. When it is necessary to establish a navigable || communication between separate valleys or basins of country, and where a double lockage is unavoidable, the summit which divides them is generally too high to permit a regular supply of water being drawn directly from the streams on either side : or these streams are not unfrequently appropriated to the ser. vice of mills and manufactories, as in the cases of the Langue- doc canal in France, the Grand Junction and many others in England, and the Forth and Clyde canal in Scotland. Under these circumstances, it becomes necessary to collect the flood- waters of the adjacent higher grounds into proper reservoirs, to be drawn off as occasion may require. The choosing a pro- per situation for a great reservoir, requires all the skill of the engineer. Much must always depend upon local circum- stances, but some of the principal objects to be had in view, are, 1st. That the reservoir should be sufficiently low to collect the flood-waters from an ample surface of country. 2d. It should be so high as to enable all the water it contains to be drawn into the summit of the canal. 3d. It is desirable that the basin to be laid under water, should contract towards its lower extremity, so as to require a comparatively short em- bankment, or head; and this head should. be placed upon a substantial foundation. 4th. It is very important that the bot- tom and sides of the reservoir should be naturally impervious | to water, otherwise much trouble and expense will be required | to render them so, by “artificial means. “5th; "The dimensions of the embankment will be regulated by its height, and the nature of the materials with which it is to be constructed. It is, however, usual to assume the height of the top bank to be from three to four yards above top water when the reservoir is full ; the breadth of the top to be five yards; the outside to slope at the rate of three horizontal to one perpendicular, and the inside slope at the rate of two horizontal for one perpen- dicular.—But these and similar erections must depend almost entirely upon the nature of the country, and the localities of situation, for which no specific rules can be given. Indeed, it is worthy of notice, and the consideration may lead to renewed exertions, that in the various branches of inland navigation in this country, the most valuable inventions and improvements have not originated so much in the depth of science, as in the application of practical skill, and ingenious experiment founded on a few general principles. Summary of our Observations on Canal Locks.-The most natural form of a lock is that which approaches nearest to the figure of the boats which are to use it. The width must only be a little more than that of the boat, and it must be the same throughout, as the boat has to pass along the whole lock: and the length may only exceed that of the boat by a space suffi- cient to admit the opening and shutting of the gates. A long rectangle is the natural figure of a boat, and therefore of a dock: besides, it will consume less water than a circular dam in passing the boat; and may be filled and emptied in three minutes, as is the case with the locks of the Clyde and Forth canal in Scotland: moreover, the expense of construction, agreeably to this form, is less than any other shape. The locks of Languedoc canal, in France, are circular or oval, see figs. I and 3. Those of the canal of Brussels and others in Holland, are rectagonal, but of such extensive chambers as to admit several vessels at once, which is attended with waste of water, and great delay in the passage of the boats. Tide locks, as those of the great Sas at Slykens, near Ostend, may admit several vessels of from 300 to 800 tons. The length and breadth of every rectangular lock should be proportioned to the size of the vessels or boats designed to pass through this lock, as in the Caledonian canal, fig. 5, where the length is 175 feet, and the breadth 49 feet. Canals of the first order, as the Forth and Caledonian, admit vessels of 19 and 39 feet beam, fig. 6; canals of the second class, vessels of 14 feet beam; and central canals, or those of the third class, 7 feet beam. In England there are but two kinds of canals, called large and small section canals, according as their breadth and the size of their locks permit the passage of large or small boats. All | the canals, of large and small size, have not a determined relative size of locks, but they rarely exceed, in their difference of dimensions, the following proportions: * Sections. Canals } º: sections, length of the locks . . . . . { # . 6. . Width of the lock-gates........ { 15 . 1 - - 8 . 6 Of the Profile of Lock-walls.-The late Mr. Jessop made these walls of equal thickness from the base upwards, leaning them backwards, so as by retiring the centre of gravity, to enable the wall to resist better the lateral pressure. The natural slope of the triangle of earth is chamfered off at the angle of repose, or 35 degrees. If A B C D, in the figure, be the erection of the wall, A 13 - - K. and B C the move- able part of the earth |R - supported by the waſl; (PTi r-e- º then taking G the cen- Ö - X, tre of gravity of the - earth, and F that of H the wall, and draw- ing the perpendiculars G H, G I, G. K, and FL; G H represents the direction of the . gravity of the earth, GI the direction of the Fº | D | * W 716 M A V N A v DICTIONARY OF MECHANICAL SCIENGE. support given by the firm inclined plane CE, and GK of the horizontal thrust against the wall A B C D. The back of the wall is supposed to be smooth, and of course only to be acted upon perpendicularly ; and the wall itself to be a solid mass, which can only be turned over the front angle of its base, or toe of the wall D. It resists this by its own weight, which may be supposed to be concentrated in the centre of gravity, and to act in the vertical line FLW. If W represent the weight of the wall, and P the horizontal thrust of the earth, M D and D L will be the two arms of a lever by which these forces are kept in equilibrio. * Now we know that M D or K C are two-thirds of B C ; that the weight of earth is proportional to the area B C E, that is, to one-half of B C X BE; and that this weight in G H is to the thrust in G. K. as E B is to B C. . The thrust is, therefore, equal to $ B Cº.; and multiplying by its distance M D from the fulcrum D, that is, by 3 BC, we have its oversetting force equal to A B Cº. Consequently, the oversetting force of earth supported by walls of equal thickness is as the cube of the height. Now for the counter resistance of the wall, it is evi- dent that its weight will be as the area A B C D, which in a rectangular wall is B C x CD; and in that case also we will have the distance L D from the fulcrum - # DC, or that the resistance is 3 BC x C D*, making this force equal to the former, or + B Cº, we find C D = B C V4 = -8165 × B C. The breadth of an upright retaining wall, must therefore be proportional to the height, and, to be of equal specific gravity with the stuff, must be upwards of four-fifths of the height. This, however, is different from what is found sufficient in practice. A brick wall, to support earth, is made four-sevenths of its height; of a stone wall #, or about half the height, when the earth is supposed to act not parallel to the horizon, but in lines parallel to the slope E C. The wall cannot fall on the side next the earth, therefore, by making it lean backwards, not only is the triangle of earth or acting power diminished, but also the wall itself, by having its centre of gravity removed further from the point of conversion at the toe, is the better enabled to resist the thrust. It batters in the form of a mere pavement over the slope of earth; all that is necessary, being to secure the foot from sinking or sliding forwards into the canal. - - Coehorn, adopting the opinions of some old German engi- neers, and designing walls for the soil of Holland, gives them three feet of thickness in front, and leaving nearly as much behind, supported by long and thin counterforts, that are connected together by two rows of arches one over the other, and also by two walls arched horizontally against the earth. Gauthey, a French engineer, who constructed the canal of Charalois, shews, by experiments made with sand and shot against a smooth plane, that the pressure acts at the centre of gravity, or one-third of the height of the wall, and is the same whatever be the slope; that in a plumb wall, if the weight of the wall be three times the acting power of the earth, and base two-ninths of the height, there is an equilibrium against over- setting. The acting power in practice, is one-fourth of the weight of the triangle of the earth, with a slope of 45°, or one- half of the square of the wall. He then shews that retreats may be made in the back of the wall so as to take off all act- ing power, and that a wall 2 feet thick and 30 feet high, bat- tering #3, with counterforts of 3 by 4, and 18 asunder, joined by two arches of 2 feet thick, is abundantly strong. Such a wall he employed with admirable success, for one of the quays of the Saone; and it is evident, that the saving of masonry, com- pared with the common construction, is immense. Brick on bed, with a sufficient batter, and corbels made by laying one brick endways in the wall, so that half of it projects behind, will create a sufficient friction to allow 20 courses to be piled against loose sand without derangement. In locks, allowing for the film of water that may insinuate itself between the masonry and the earth, taking the speciſic gravity of stone as 2} times that of water, the proper thickness will be the depth multiplied by 0.365 or little more than }, and one-half the depth will be sufficiently ample in any case. The upper part of the wall is usually perpendicular, the lower suited to the shape of the vessels, or rounded off. The walls of the quays of one of the basins of the Fazeley canal, are covered with plates of cast-iron, joined by tenons and mortises fixed to the masonry with screw bolts; and in this canal we descend 246 feet by 38 locks in a space of eight miles. Mr. Telford, in the fine construction of the aqueduct of Pont-y-Cyssyltan,” 126 feet above the level of the river, and 1010 feet in length, erected nineteen metal arches on eighteen piles of brick, to two abutments of stone; above these arches of the aqueduct of Chirk, he built side walls with brick in the usual manner, but with stone coating. Between these walls he laid down large plates of cast-iron, for the bottom of the canal, carefully clamped, then fastened with iron pins, screwed and caulked in the joints: these plates serve at the same time as continued holdfasts, in order to prevent the side walls from being thrown downwards by the pressure of the fluid. To give the structure a greater resistance against the pressure of the water, the sides of the canal are composed of strong plates of wrought-iron, not cut straight, but so formed as if they were a continuation of the lines presented by the solid parts of the ribs of the bridge; and the plates which join the parts of one arch with those of another, are wider at the bottom than at the top, which produces the same effect as that of buttresses sup- porting a wall. The lower portion of the lock may be suited, we said, to the shape of the vessels which navigate it, and therefore it will allow the wall to be made with a considerable batter, or slope, to the front, by which means the point of con- version being farther removed from the centre of gravity of the wall, the stability will be considerably increased without an increase of materials; the point of conversion, to be sufficiently secured to prevent sliding, ought to be inserted some way into the ground of the foundation. - - There is yet another principle by which the profile of the lock-wall must be regulated; the transpiration of the waters from the upper pond to the lower, beneath, or by the side of the lock, must be prevented. This is effected by rows of sheet or plank piles, (as in fig. 1,) carried across the site of the lock, and driven a considerable way under its i foundation. The points are champered off, so that in driving each may be forced close against the preceding one : still further to secure the seam joint against the transpiration of water, it is not uncommon to groove the piles (as in fig. 2,) on one edge, and make a ridge on the other; or to groove each side, and slip a feather of a different wood into these grooves. The plank piles are again fastened to stout hori- zontal beams of timber, extending in the line of the proposed sheet plank piling, and fastened to - __IT stout upright piles of balk, CF-E-F-H-II placed at certain distances Fig. 1. /// Fig. 2. |/ ;" | - - in the same line, and called gauge piles. The film of > > > X water that is filtred under - the floor of the lock being connected with the upper - ond, acts upwards by a 5TETE THE LE -T Hºur: sº to 'a. - head of water, or difference between the waters above and within the lock, and unless the weight of the side walls be sufficient to counteract this, the bottom of the floor will give way, and be blown up. The float- ation of a timber floor, and the weight of an inverted arch, will, in some measure, counteract this, when the section of the masonry in the walls and bottom is two-thirds the area of the . open space of the lock. We may assume the specific gravity * The archduke John of Austria, when viewing the magnificent aqueduct of Pont-y-Cyssyltan, expressed astonishment that nothing had been pub- lished respecting a structure, “ which,” said the prince, “in France would have produced three folio volumes!” What a fine compliment on the merit and modesty of Mr. Telford? - - N A v N A V DICTIONARY OF MECHANICAL scIENCE. 717 of the building, (see fig. 3,) 2} times that of the water: it will therefore compensate for an opening of 1% times its bulk, when the whole is immersed: when there is no invert, the average thickness of the walls is one-third the width of the lock; when there is an invert, they may be much less. In great locks connected with rivers, those moving roads and feeders of canals, or connected with lakes or the sea, all the resources of hydraulic engineering are put in requisition. . - In constructing the side walls of locks, a permit the gates to fall back out of the way of vessels, as is shewn in the canal, of Languedoc, and the Caledonian canal, figs. 1 and 5, Plate of Locks; and it is not uncommon to make those for the upper gates act as waste weirs, fig. 7, Plate of Ilocks, or overfalls, to discharge the superfluous water of the canal into the paddle-holes, or conduits of stone or brick 18 JFig. 3. inches diameter, by which the water of the upper level is con- veyed into the lock chambér. From the lock it is usually con- weyed into the lower level through sluices formed in the gates, fig. 2, below the level of the low water. The paddle is moved by a crank and pinion working into a toothed rack, see fig. 2. The exterior portion of the lock, above the upper and below the lower gates, is named the forebay and tailbay of the lock, in the Caledonian canal. The lock gates are usually framed of timber, figs. 2 and 4, though, I believe, iron is greatly used in the small canals in England. I know it was used in framing the large gates of the Caledonian canal, (see the Plate Locks, GATes, &c. figs. 7 and 8,) and in the New Graving Dock at Dundee. For the purpose of securing water in the locks, solid plungers in parallel chambers, raising and depressing boats in caissons or frames, by chains passing over large wheels, and by means of working air vessels, have been projected and tried in model, but seldom in practice. Inclined planes connecting different canal levels have existed in China from time imme- land, as a species of rail road. Waste weirs are either constructed across rivers, to force the water from them into the conducting feeders, or imme- diately into the canal itself, or they permit the surplus water to pass off the canal. It is also requisite to have wastes adja- cent to locks, to convey water from upper to lower levels, with- out passing through the locks. To canals belong also aque- ducts, bridges, oblique arches, or skewed bridges, stop-gates, and let-offs. See Locks and Docks. - NAVY, implies in general any fleet or assemblage of ships of war, which belong to a kingdom or state. . - Of the arts and professions which attract notice, none is more astonishing and marvellous than navigation in its present state, comparing the small craft of antiquity to a majestic first- rate, containing 1000 men, with their provisions, drink, furni- ture, apparel, and other necessaries for many months, besides 100 pieces of heavy ordnance, and bearing all this vast appa- ratus safely to the most distant shores. How great is the dis- parity ? 8000 lbs. of provisions are required daily in such a ship. Suppose her fitted out for three months, we shall find her laden with 723,000 lbs. of provisions. A cannon; if called a forty-two 5,500 lbs. if made of iron ; there are twenty-eight or thirty of these on board a ship of 100 guns; their weight, exclusive of their carriages, amounts to 183,000 lbs. On the second deck, thirty twenty-four pounders; each weighing about 5,100 lbs. and therefore altogether, 153,000lbs, ; and the weight of twenty- eight twelve pounders on the lower ‘deck, amounts to about 75,400 lb. ; fourteen six-pounders on the upper deck, to 26,000lb. and on the round tops, there are: three-pounders and swivels of smaller size...The complete charge of a forty-two-pounder weighs about 64 lb., and upwards of 100 charges are required for each gun. All this amounts nearly to the same weight as the guns themselves. Every ship must be provided against exigencies, with two sets of sails, cables, cordage; and tack- lings: the stores, likewise, consisting of planks, pitch, and to W º * Small arms, bayonets, swords, and pistols, make no recess is made, to inconsiderable load, to which we must finally add the weight of the crew ; so that one of those large ships carries at least 2000 tons burden, and at the same time is steered and govern- ed with as much ease as the smallest skiff on the Thames. The British naval force, during the late war, (on the 1st of | January 1813,) was as follows:—at sea 79 ships of the line; nine from 50 to 44 guns; 122 frigates; 77 sloops and yachts for bombs, &c.; 161 brigs; 54 cutters; 52 schooners, &c. In port and fitting, 39 of the line ; 11 from 50 to 44 guns; 29 fri- gates, hospital ships, prison ships, &c. 28 of the line; two from 50 to 44; two frigates; one yacht. Ordinary and repairing for service, 77 of the line; 10 from 50 to 44 guns; 70 frigates; 37 sloops: 3 bombs, 11 brigs; 1 cutter; 2 schooners. Build- ing; 29 of the line; four from 50 to 44 guns; 15 frigates; 5 sloops, &c. 3 brigs. A fleet of ships of war is generally divided into three divi- Sions; and commanded by admirals, vice-admirals, or rear- admirals, of the white, blue, and red flags. A squadron of ships is a division or part of a fleet com- manded by a commodore, or by a rear or vice-admiral. The number that forms a squadron is not fixed, for a small number in a body and under one commander may make a squadron. If the ships are numerous they are sometimes divided into three squadrons, and each squadron may be again divided into three divisions. - • - - A frigate is a light-built fast sailing ship, having commonly two decks, whence that called a light frigate is a frigate with only one deck. These vessels mount from 20 to 44 guns, and make excellent cruisers. - • * , Hulks are old ships cut down to the gun-deck, and fitted with a large wheel for careening. Their gun-decks are from 113 to 150 feet long, and from thirty to forty feet broad; they will carry from 400 to 500 tons. Hulks are also employed at Woolwich, Portsmouth, Sheerness, &c. to receive convicts under sentence of transportation; the vessels are moored at such a distance from shore, as precludes the possibility of the men's escape; and the convicts are taken daily on shore to | work, under a strong guard, at pile-driving, harbour cleansing, morial, and they have been long usefully employed in Eng- and other employments in the several public departments. A hoy is a small vessel or bark, whose yards are not across. nor the sails square, like those of ships, but the sails like a mizzen, so that she can sail nearer the wind than a vessel with cross sails can do. . . . . . . . . . . . . . . Sloops are appendages to men of war, about 60 tons bur- -den, and carrying 30 men. They are light vessels, with only a small main-mast, fore-mast, and lug-sails to haul up and let down, on occasion, and "are commonly fast sailers. Smacks are small vessels with one mast; they sometimes are employed as tenders on a man of war: they are also used for fishing upon the coasts. - Store ships are generally ships of from 300 to 600 tons; they carry ordnance and military stores to the out-ports, or to an army when abroad. º A yacht, a vessel for the conveyance of passengers, is also sometimes adorned for regal use. It is furnished with masts and sails, has one deck, carrying from four to twelve guns with from twenty to forty men; burden from thirty to 160 tons. They are used for running, and making pleasure excursions. A galley is a low-built Mediterranean vessel, having oars | and sails. Galleys have usually twenty-five or thirty benches pounder, weighs about 6,100 lb, if made of brass; and about of oars on each side, and four or five galley slaves on each bench. The galley usually carries a large gun, two bastard pieces, and two small pieces. It is from twenty to twenty-two fathoms long, three broad, and one deep, and has two masts, viz. a main-mast, and a fore-mast, which may be struck or lowered at pleasure. . . . e Naval Distinctions in Rank.—The Lord High Admiral of Eng- land is an officer of great trust; the king is nominally Lord High Admiral, while the duties of the office are executed by commission, called the Board of Admiralty, consisting of five commissioners denominated Lords of the Admiralty, one of whom, as resident, is called First Lord. - The Board of Admiralty takes cognizance of every thing transacted at sea, the management of all maritime affairs, the direction of the navy, and both civil and criminal offences committed on the high seas. Under this court is also a court 8 U. 718 N E C * N A V DICTIONARY OF MECHANICAL SCIENCE. merchant, or court of equity, where all differences between merchants are decided according to the rules of the civil law. This court is held three or four times a year at the Old Bailey, and one of the judges generally acts as the Lord Admiral's deputy. - An 'Admiral is a great officer, who has the government of a navy, and the hearing of all maritime causes. In our navy, besides the admiral in chief, there are the Vice-admiral, who commands the second squadron; and the Rear-admiral, who commands the third division. The admiral carries his flag at the main ; the vice-admiral, at the fore-top mast head; and the rear-admiral at the mizzen. The admiral ranks with gene- rals in the army. A Captain commands a ship of the line of battle, or a frig- He is not only answerable for any bad conduct of the military government and equip- ate carrying twenty or more guns. ment of the ship which he commands, but also for any neglect of duty. - - A Lieutenant, an officer next in rank and power to a captain, in whose absence he commands, musters the men at quar- ters; visits the ship during the night watches; exercises the men in the use of small arms. First-rates have six lieutenants; a sixth-rate has only one. - Midshipmen, generally youths appointed by the captain of the ship, second the orders of the superior officers, and assist in all duties on board or ashore. In a first-rate there are twenty- four of these, in inferior rates from eight to four. - A Pilot conducts the ship into harbour through intricate channels. This is properly a coasting pilot; one for the high seas can use the quadrant, take observations, and steer a ship from port to port. The Purser receives the victuals, takes care they be good, and regularly served out to the ship's company. According to the purser's books the men receive their pay. The Steward acts under the purser. - - The Victualler furnishes the ship with provision and stores. The Clerk sees that nothing be wasted, and keeps a journal of the loading of a merchant ship, &c. the bargains, purchases, and sales the ship makes from its departure; the consumption of provisions; and every thing relating to the expense of the voy- age. In sumall vessels the master or mate is also clerk. A mate is the second in subordination, as a master’s mate. The Surgeon and Chaplain resemble the same officers in the army. - Marines have nothing to do in working the ship, but defend it in war, and attack the enemy when fighting. There is ge- nerally a company aboard each ship, about forty in number, under a captain and two lieutenants. The present establish- ment of marines amount to more than 30,000. Their princi- pal stations are at Chatham, Woolwich, and Portsmouth. In a sea-fight their small arms are of very great advantage in scour- ing the decks of the enemy, and when they have been long enough at sea, they must be infinitely preferable to seamen, if the enemy attempts to board, by raising a battalion with their fixed bayonets. . - Officers of the navy are, the treasurer, who receives monies out of the exchequer to pay charges of the navy. The control- ler, who attends and controls all payments of wages, knows all the rates of stores, examines and audits all accounts. The surveyor knows the state of all stores, sees all wants supplied, estimates repairs, &c. and at the end of each voyage, audits and states all accounts. The clerk of the acts records all orders, contracts, bills, warrants, &c. Navy bills, or victualling bills, are orders for the payment of money, issued by the commissioners of the navy on the treasu- ry of the navy, in payment for stores, &c. furnished by contract for the use of his majesty’s dock yards, and the navy. These bills, since 1796, are negotiated like bills of exchange, payable at ninety days after date, and bearing interest at 3%d. per cent. per diem. The privileges conferred on sailors are much the same as on soldiers, with regard to relief, when maimed, wounded, or superannuated. Greenwich Hospital receives such seamen as are disabled from further service, and provides for the widows and children of such as are slain. The royal Navy of Great Britain is conducted under the di- rection of Lords of the Admiralty, by the following principal of the navy by warrant from the principal officers. officers, who are commissioners, and compose the board for managing the business thereof. I. Comptroller of the navy, who attends and controls the payment of all wages, as to know the rates of stores, &c. 2. Supervisor of the navy, who is to know the state of all stores, to supply what is wanting, to estimate repairs, charge boatswains, &c. with the stores they receive, &c. There have been generally two joint surveyors. 3. Clerk of the acts, whose business is to record all orders, contracts, bills, warrants, &c. 4. Comptroller of the treasurer’s accounts. 5. Comptroller of the victualling accounts. 6. Comptroller of the store-keeper's accounts. 7. One extra-commissioner. The annual appointment of each commissioner is 500l. In time of war, or great naval exertion, there are other extra-commis- Sioners, and commissioners are then appointed to reside at some of the principal yards abroad. The treasurer of the navy has an appointment of 2000 per annum. His business is to receive money out of the exchequer, and to pay all the charges Each of these commissioners and officers has a number of subordinate clerks with various salaries. NAVY, is also used to denote the collective body of officers employed in his majesty’s sea service. - NAVY Board, the commissioners of the navy collectively con- sidered. k NAVY Office, the office where the accounts of the navy are ept. - - NAZARENES, a term originally applied to Christians in general, but afterwards to the sect who blended the institutions of the Mosaic law with those of the gospel. NAZARITES, among the Jews, persons dedicated to the observation of Nazariteship, either for only a short time, or all their lives. All that we find peculiar in the latter, is, that they were to abstain from wine and all intoxicating liquors, and never to shave or cut off the hair of their heads. The first sort of Nazarites were moreover to avoid all defilement; and if they chanced to contract any pollution before the term was expired, they were obliged to begin afresh. .NE ADMITTAS, in Law, a writ directed to the bishop, at the suit of one that is patron of a church, where on a quare impedit, &c. depending, he is doubtful that the bishop will col- late his clerk, or admit the other's clerk, during the suit between them. NEAP TIDEs, are those which happen when the moon is nearly at the second and fourth quarters: the neap-tides are low tides, in respect to their opposites, the spring tides. NEAPED, the situation of a ship which is left aground on the height of a spring tide, so that she cannot be floated off till the return of the next spring. - NEBULA, a luminous part of the heavens, called, the Milky Way, which consists of myriads of fixed stars too small to be seen by the naked eye, and visible only by the best glasses. Some of these nebulae consist of clusters of telescopic stars; others appear as luminous spots of different forms. Each nebula is thought to be composed of a number of suns, and each sun is probably destined to give, light to a system of worlds. There are also nebulous stars, that is, Stars surrounded with a faint luminous atmosphere. NECESSITY, whatever is done by a necessary cause, or a power that is irresistible, in which sense it stands opposed to freedom. The law charges no man with default where the act is compulsory, and not voluntary, and where there are not a consent and election; and therefore, if either there is an im- possibility for a man to do otherwise, or so great a perturbation of the judgment and reascn as in presumption of law man's nature cannot overcome, such necessity carries a privilege in itself. Necessity, Philosophical, maintains that the volitions and actions of intellectual agents are produced by causes equally deciding and resistless as those which are admitted to actuate the material system of the universe. Wherever the sun shines, or the rain descends, it is impossible to conceive, that in situ- ations precisely similar to those which immediately precede these events, the ray should be withheld, or the cloud should remain suspended in the atmosphere. The diffused splendour, and the falling moisture, are universally allowed to be in such situations invariably and inevitably the results. The doctrine N E P N. E. T. 719 DICTIONARY OF MECHANICAL scIENCE. of necessity extends to the mind what is thus obvious and un- contradicted with respect to matter, and insists on the abso- lute and uncontrollable influence of motives upon the human will and conduct. It asserts, that the determinations and actions of every individual flow, 'with unfailing precision and resistless operation, from the circumstances, motives, or states of mind; by which they are preceded; and that, in the whole series of his existence, no specific feeling, thought, or act, could have been different from what it really was, these pre- vious circumstances continuing the same. In the consideration of this subject, it is important not to confound necessity with compulsion, as the latter implies that the choice of the mind is effected with reluctance, and in consequence of the exercise of force upon inclination; whereas, whether the conclusion be formed with the full ooncurrence of the affections, or after a conflicting estimate, which leaves reason completely triumphant over inclination; the mind is equally impelled by some con- trolling energy, and equally necessitated to the determination it adopts. It is of consequence also to the illustration of the sub- ject, fully to comprehend the meaning of the term motive, which, it is to be remembered, comprehends both the bias of the mind and the end in view, and includes every thing that moves or influences the mind, and excites it to a choice or determination. - NECROMANCY, a pretended divination by raising the dead and extorting answers from them. - Bolt Rope Need LE, a large needle with a triangular point, used to sew the bolt-rope upon the sails. - Sail Needles, are needles used for sewing the seams of sails. - - NE EXEAT REGNO, is a writ to restrain a person from going out of the kingdom. NEGATIVE QUANTITIES, are those quantities which are preceded or effected with the negative sign. NegAtive Sign, in Algebra, that character, or symbol, which denotes subtraction, being a short line preceding the quantity to be subtracted, and is read minus ; thus a–b denotes that the quantity b is to be taken from the quantity a, and is , read a minus b, like signs produce plus, and unlike signs minus, hence —ax —b-+a b. The introduction of this character has given rise to various controversies, with regard to the legality or illegality of certain conclusions depending upon it; some maintaining, that as a negative quantity is in itself totally ima- ginary, it ought not to be introduced into a science, the excel- lency of which depends upon the rigour and certainty of its conclusions; while others running into the opposite extreme, have endeavoured to illustrate what will not admit of illustra- tion; and thus, like other zealots, have been the greatest ene- mies of the cause they were so anxious to defend. It is vain to attempt to define what can have no possible existence; a quantity less than nothing is totally incompre- hensible ; and to illustrate it, by reference to a debtor and creditor account, to say the least of it, says Barrow, is highly derogatory to this most extensive and comprehensive science. NEGRO, a name given to a variety of the human species, who are entirely black, and are found in the torrid zone, especially in that part of Africa which lies between the tropics. NEPA, Water-scorpion, a genus of insects of the order hemiptera, of which there are fourteen species, inhabiting stag- nant waters, and preying on the smaller water insects, &c. NEPENTHES, a genus of the dioecia syngenesia class and order, an herbaceous plant of Ceylon. The leaves are alternate, partly embracing the stem at their base, and terminated by tendrils, each of which supports a 'deep, membranous urn, of an obiong shape, and closed by a little valve like the lid of a box. In the morning the lid is closed, but it opens during the heat of the day, and a portion of the water evaporates; this is replenished in the night, and each morning the vessel is full, and the lid shut. . • . . NEPETA CALAMINTHA. Field Calaminth. The Leaves. This is a low plant growing wild about hedges and highways, and in dry sandy soils. The leaves have a quick warm taste, and smell strongly of pennyroyal: as medicines, they differ little otherwise from spearmint, than in being somewhat hotter and of a less pleasant odour; which last circumstance has pro- cured calamint the preference in hysteric cases. NEPETA CATARIA. Nep or Catmint. The leaves.—This is a moderately aromatic plant, of a strong smell, not ill resem- bling a mixture, of mint and pennyroyal ; it is also-recommend- ed in hysteric cases. - - - - NEPHRITE, in Mineralogy, a species of the talc genus; it is also called jade or jade-stone, and was formerly celebrated for its medicinal virtues. It is of a dark leek-green colour, verg- ing to blue, and is found in Egypt, China, America, the islands in the Pacific ocean, and in the Siberian mountains, some- times adhering to rocks, and sometimes in detached round pieces. It is highly prized by the Hindoos and Chinese, by whom it is made into talismans and idols, and by the Turks, who form it into sword and dagger handles. NEPHRITIC, something that relates to the kidneys. NEPHRITIC WooD, a wood of very dense and compact tex- ture, and of a fine grain, brought from New Spain, in small blocks, in its natural state, and covered with its bark. It is to be chosen of a pale colour, sound and firm, and such as has not lost its acrid taste. This wood is a very good diuretic, and it is said to be of great use with the Indians in all diseases of the kidneys and bladder. It is also commended in fevers and obstructions of the viscera. Among the Indians it is used only with an infusion in cold water, - NEPTUNIAN THEORY, in Geology, endeavours to ac- count for the various geological phenomena, on the suppo- | sition that the matter of which the exterior part of the earth is . composed was once in a state of watery solution. Its chief supporter is Werner. It is opposed to the Plutonic or Vul- canic theory, which supposes the phenomena to have resulted from the matter of the earth having been in a state of fusion by fire; of this theory Dr. Hutton is the principal champion. That the surface of our globe was once in a fluid state, is esta- blished by very ample evidence. In the greater number of the strata of the earth, in the most elevated, as well as at the greatest depths, substances are found in a crystallized state; and even many of these strata have marks of crystallization in their entire structure. Crystallization is the arrangement of particles in a regular determinate form ; and it necessarily im- plies a previous state of fluidity, which would allow these par- ticles to arrange themselves in positions necessary to produce these forms. Many of the more solid strata contain in their substance remains or impressions of animals and vegetables: and it is obvious that, to admit of the introduction of such sub- stances, they must at one time have been, if not in a perfectly fluid, at least in a soft or yielding state. In addition to this, the general disposition of the materials of the globe, so far as has been explored, must have arisen from fluidity, as this only could have arranged them in beds or strata, parallel to each other, and preserving that parallelism to a great extent. These appearances are not partial, but extend to the whole surface of the earth, and prove beyond a doubt its former fluidity. There are only two ways by which that fluidity can be sup- posed to have taken place: either the solid matter must have been fused by the action of heat, or it must have been dis- solved in some fluid. These are the primary principles upon which the geological theories have been formed, under dif- ferent modifications. - NEREIS, in Natural History, a genus of the vermes mol- lusca class and order. There are about thirty species, in separate divisions, found in most seas, and are highly phos- phorous, giving a lucid splendour to the waves in the evening. NERVES, cylindrical whitish parts, usually fibrose in their structure; or composed of clusters of filaments, arising from the brain, or rather from its medulla oblongata within the skull, and from the spinal marrow, and running from thence to every part of the body. NET, a device for catching fish and fowl. The making of nets is very easy. All the necessary tools are wooden needles of different sizes, some round, and others flat: a pair of round- pointed and fiat scissars, and a wheel to wind off the thread. The strength of the packthread, and the size of the meshes, must be according to the fishes or birds to be taken. The natural colour of the thread in many cases to be altered. The most usual colour is the russet, obtained by plunging the net into a tanner's pit, and letting it lie there till it be sufficiently tinged. A green colour is given by chopping some green 720 N. ET N E T DictionARY. of MECHANICAL SCIENCE. wheat and boiling it in water, and then soaking the net in the tincture. A yellow colour is given in the same manner with the decoction of celandine, which gives a pale, straw colour. NETTING, a sort of fence, formed of an assemblage of ropes fastened across each other, so as to leave uniform intervals between. These are usually stretched along the upper part of a ship's quarter, to contain some of the seamen's hammocks, and secured in this position by rails;and stanchions. Nettings are also used for containing the fore and main top-mast stay- sails when stowed. º Boarding NetTING, a netting extending fore and aft from the gunwale to a proper height up the rigging. Its use is, to prevent an enemy jumping aboard, on to the decks, in an en- gagement, &c. ºr ... NET WORK, BuchanAN's MACHINe for WEAviNG.-The object of this newly invented machine, is to weave, expeditiously and without knots, any kind of net-work, and to 'allow the holes or meshes of the net-work to be enlarged or diminished according to the option of the operator. . . . . *- Alexander Buchanan of Paisley, the inventor, adds another instance to the number of proofs that he has already given of his inventive genius, and ardent desire to improve the arts and manufactures of his native country. The machine in question consists of the following parts:—A B C D, fig. 1, represents a wooden stand upon which an iron frame, EFG H, is sup- ported at each corner. In this frame there are seven wheels, 1, 2, 3,4,5,6,7, that pitch into each other. i, k, l, m, are conti- nuations of the axis of the wheels numbered 1, 2, 5, 7. Upon the ends of the axis thus continued, circular pieces of wood, I, K, L, M, are fixed, a perspective view of which is given at fig. 2. The other wheels, 2, 4, 6, are introduced in order that when the machine is put in motion, those numbered 1, 3, 5, 7, may turn in the same direction, as it is necessary that the parts of the machine attached to the axis of these should do so. Into each of the circular woods, four grooves are cut, which allow a “s º m – *\º- Śº $!!…@ AT § X G º 4. P . [...] s] lºº - N . . t . . ; the shuttles, a, b, c, d, e,f, g, h, to slide out and in at the cir- cumferences of the circular woods, but prevent them from com- ing out when drawn in a direction towards R. The shuttles, ºne of which is represented at fig. 3, consist of three parts. A, fig. 3, is that part which slides into the grooves B, the project- ing part, and C, that which holds the pirn or bobbin. The use of the grooves is to allow the shuttles to be moved from one circular wood to another in crossing the threads to form meshes of the net-work, and to afford an easy method of attaching them to the circular woods, after that they have been thus moved. In fig. 1, the circular woods are represented as turned half round, to shew the grooves and shuttles in them. The grooves in this case are perpendicular to the wooden stand: it must |heºbserved; however, that they lie horizontally when the "shuttles are moved from one circular wood to another. This is necessary both for weaving the net-work properly, and for moving the shuttles with greater facility. Fig. 4, represents one of the pirns or bobbins. One end A, is considerably, thicker than the other, and has a groove in it, which, when the pirn is put on C, fig. 3, admits a spring D. This spring acts as a counterpart to a weight that is suspend- ed from the ends of the threvels, one of which proceeds from each pirn to keep them from entangling with each other. Each of the shuttles is furnished with a spring, all of which must in- dividually be so strong, that their aggregate strength will pre- vent the weight from drawing the threads off the pirns, and at the same time sufficiently weak, to allow the threads to come easily off the pirns when drawn by the operator. Into the cen- tre wheel 4, fig. 1, another pitches, having the same number of teeth; this wheel, which cannot be represented in the figure, is fixed to one end of the iron rod O, P, and at the other end of it a handle N is fastened. By this handle the machine is put in motion. The iron rods O, P, turn in two gudgeons, one of which is concealed by the iron frame, the other is represented at S. * Having now given a description of Mr. Buchanan's simple and ingenious machine, the method of using it will easily be comprehended. The pirns having been previously filled with thread, or with any substance of which the net-work is to be wrought, are placed on the shuttles. The ends of the threads are then collected and tied together, after which they are put through a ring that is fastened on the top of the gudgeon S, fig. 1, and also through a hole T, in the sole or wooden stand; a weight is then suspended from the threads, the use of which, as was already mentioned, is to prevent them from entangling. It must be observed, however, that before the machine is put in motion, the shuttles occupy the proper grooves. This par- ticular is illustrated in fig. 1, where the shuttles a, b, in the circular wood, I, occupy the second and fourth grooves ; those of K, H, c, d, occupy the second and fourth; those of L, the first and third ; and those of M, H, the second and fourth. The operator commences weaving the net-work by turning round the handle at N. The size of the meshes of the net-work, he enlarges or diminishes at pleasure, by turning the handle a greater or less number of times. By turning round the han- dle, the wheels in the iron frame, and the circular pieces of wood that are fixed to the axis of four of those wheels, are made to revolve; but when these pieces of wood are revolving, the threads which proceed from the shuttles of each are twin- ing round each other. The twist made by this movement is made tight by the operator, who puts a finger of his left hand between each pair of threads, and with his right hand inserts, horizontally, the clearer, which is a thin piece of wood, shaped like a paper cutter, between each pair of threads, drawing both his hand and clearer towards R, at which place it is prevented from going any farther by a knot. He then removes his hand, leaving the clearer to keep the twist tight, and crosses the threads to form the meshes. This is effected by moving the shuttles from one circular wood to another. This operation resembles, and effects exactly, the same object as the crossing of the pins in working lace. The shuttles of the middle circu- lar woods are charged first. Those of the circular wood R, occupying the second and fourth grooves, are moved into the second and fourth of the circular wood L, while those of L are shifted into the first and third grooves of K. This movement forms half a mesh. The operator then turns round the handle the same number of times as formerly, to twist the other sides of the mesh that is already half formed, and also to twist the sides of other two meshes. This being done, and the twist made tight by the method just explained, the threads are again crossed, which is done as formerly by moving the shuttles from one circular wood to another. In the former instance, only the threads of the middle circular woods were made to cross each other; in this, however, the 'whole must be crossed, and, consequently, all the shuttles’ will require to be moved into I; those of I into K; and those of L are moved into M ; while those of M are moved into L. . . N E W N I C DICTIONARY OF MECHANICAL SCIENCE. 721 - By the first moving of the shuttles, those of the circular wood Y were shifted into the corresponding grooves of L; and those of Lºwere moved into the corresponding ones of K ; so that by shifting them in the present instance, those that originally oc- cupied the circular wood L, are moved into I ; and those that originally occupied K are moved into M. ... This operation com- pletes othér two meshes. Thus, by twisting and crossing the threads, any quantity of net-work may be wove : the operator drawing more thread off the pirns as the former quantity is used. .” - * “In deseribing the method of using Mr. Buchanan's machine, we have called the substance with which the net work is wrought, thread. It is not to be understood, however, that this is the only substance which can be employed. It is a proper- ty of the machine that any kind of yarn or twine may be warped with it, so that by using fine yarn, and giving the handle a few turns, a texture may be wrought equally as fine as lace; and from the simplicity with which it may be wrought, we would strongly recommend the machine to the junior branches of families, who will find the using it to be an agreeable and pro- fitable amusement. - NEUTRAL SALTS, a sort of salts neither acid nor alkaline, but partaking of the nature of both. See AcıD, ALKALI, SALTs, &c. NEUTRALIZATION. When two or more substances mutually destroy each other's properties, they are said to neutralize each other. Thus, in a proper combination of acid and alkaline substances, the acid and alkaline properties are destroyed. - • NEWTON, DR. John, a learned English mathematician, was born in Devonshire in 1622, and died in 1678, in the 56th year of his age. He was author of several works relating to differ- ent branches of the mathematical sciences, all of them exhibiting the hand of a complete master of his subjects. Newton, SIR ISAAc, one of the greatest mathematicians and philosophers that any age or country ever, produced, was born at Woolstrop, in Lincolnshire, on the 25th of December, 1642. He very early discovered strong traits of genius, which was improved by a liberal education; at twelve years of age he was put to the grammar school at Grantham, and in 1660 was en- tered a student in Trinity College, Cambridge. He had not been long in college before he attracted the notice of the celebrated Dr. Barrow, and a sincere and lasting friendship took place between these two great men. Euclid's “Elements” were as usual first put into his hands, of which he soon made himself master, and his attention was then directed to Descartes’ analytical method, and the optics of Kepler, in both of which he made several improvements, noting them down in the margins. He continued reading the works of the most celebrated authors till about the year 1664, and at this early age it was that he first laid the foundation of his new and admi- rable Method of Fluxions and Infinite Series. In the mean time, as mathematicians were then much engaged in improving telescopes, and grinding glasses for the purpose of constructing these instruments, he also set himself to work on the same sub- ject, which led him to a repetition of Grimaldi's celebrated ex- periment with the prism. The vivid colours of the spectrum was to him, not only a source of delight and pleasure, but also of contemplation, particularly its oblong form, which, according to the principles then received, ought to have been circular; this phenomenon led him to other experiments, and finally to a new theory of light and colours, in which the heterogeneous nature of light was satisfactorily demonstrated. * It is impossible for us to follow this philosopher through the numerous and important discoveries and improvements with which he enriched science; suffice it to say, that he left Scarce any subject unexplored. Analysis, astronomy, optics, mecha- mics, were alike the objects of his investigation, and experienced alike the powerful effects of his superior genius. In his pri- vate character, he was amiable and modest; he never talked, either of himself or others, so as to give the most malicious censurer the least occasion even to suspect him of vanity. He was candid and affable, and always put himself upon a level with his company; nor did any singularities, either natural or affected, distinguish him from other men. This great man diad on the 20th of March, 1727, in the 85th year of his age, and 74. on the 28th of the same month was conveyed to Westminster Abbey, the pall being supported by the Lord Chancellor, the Dukes of Montrose and Roxburgh, and the Earls of Pembroke, Sussex, and Macclesfield. He was interred near the entrance into the choir on the left hand, where a stately monument is erected to his memory, with emblematical representations of Some of his most important discoveries in the sciences, and an inscription highly honourable to his memory. The Newton IAN Philosophy, or the doctrine of the universe, and particularly the heavenly bodies, their laws, affections, phenomena, &c. as taught and illustrated by Newton. NEW TRIAL, in Law, is not granted upon nice and formal objections, which do not go to the real merits, nor where the scales of evidence hang nearly equal. It is generally upon some misdirection by the judge to the jury, in point of law, where a jury has found a verdict directly against evidence. It is also granted where damages have been given beyond the ordinary measure of justice, and where the party has been surprised by some evidence which he has subsequently the means of answering, but had not at the trial. It is always refused where the damages do not exceed £10. NICKEL, a white metal, which, when pure, is both ductile and malleable, and may be forged into very thin plates, whose colour is intermediate between that of silver and tin, and is not altered by the air. It is nearly as hard as iron. Its spe- cific gravity is 8:279, and when forged, 8666. The species of nickel ores are its alloy with arsenic and a little sulphur, and its oxide. The first is the most abundant, and the one from which nickel is usually extracted. It is known to mineralogists by the German name of kupfernickel, or false copper, from its colour and appearance. It occurs generally massive and dis- seminated, its colour is copper-red of various shades. By the experiments that have been made, nickel in its pure state pos- sesses a magnetic power. The effect of the magnet on it is little inferior to that which it exerts on iron; and the metal itself becomes magnetic by friction with a magnet, or even by beating with a hammer. Magnetic needles have even been made of it in France, and have been preferred to those of steel, as resisting better the action of the air. The mickel preserves its magnetic property when alloyed with copper, though it is somewhat diminished; by a small portion of arsenic it is com- pletely destroyed. Nickel is fusible at 150 degrees of Wedg- wood, and forms alloy with a number of metals. Nickel is found in Cornwall, and in some other counties of England; in Germany, Sweden, France, Spain, and several parts of Asia. The Chinese employ it in making white copper ; and, in con- junction with copper and zinc, they manufacture it into various kinds of children's toys. Nickel gives a certain degree of whiteness to iron. It is used, with advantage, by some of the Birminghaun manufacturers, in combination with that metal ; and by others in combination with brass. If it were possible to discover an easy method of working nickel, there can be little doubt but it would be found very valuable for surgical instruments, compass needles, and other articles, since it is not, like iron, liable to rust. Oxide of nickel is used for giving colours to enamels and porcelain. In different mixtures it produces brown, red, and grass-green tints. NICOTIANA, in Botany, Tobacco, a genus of the pentandria monogynia class and order. Natural order of Luridae. Solaneae Jussieu. English tobacco seldom rises more than three feet in height, having smooth alternate leaves upon short foot-stalks ; flowers in small loose bunches on the top of the stalks, of a yellow colour, appearing in July, which are succeeded by roundish capsules, ripening in the autumn. Sir Walter Raleigh, on his return from America, first introduced the smoking of tobacco into England. In the house in which he lived at Islington are his arms, with a tobacco plant on the top of the shield. It is remarkable that the name tobacco has prevailed over the original name, petum, in all the European languages, with very little variation, and even in Tartary and Japan. Tobacco is derived from the island Tobago. Petum is the Brazilian name.—Tobacco is sometimes used externally in unguents for destroying cutaneous insects, cleaning ulcers, &c. Beaten into a mash with vinegar or brandy, it has sometimes proved serviceable for removing hard tumours of the hypo- chondres. 8 X. 722 N I T N ſ T DICTIONARY OF MECHANICAL SCIENCE: NICTITATING MEMBRANE, in Comparative Anatomy, a thin membrane, chiefly found in the bird and fish kind, which covers the eyes of these animals, sheltering them from the dust, or from too much light, yet is so thin and pellucid that they can see through it. . . . . . - , * NIDUS, among naturalists, a nest, or proper repository for the eggs of birds, insects, &c. wherein the young of these animals are hatched and nursed. - - NIGELLA Roman A. Fennel Flower. The seeds.-They have a strong, not unpleasant smell; and a subacrid, somewhat unctuous disagreeable taste. They stand recommended as ape- rient, diuretic, &c. but, being suspected to have noxious quali- ties, should be used with caution. NIGHT, that part of the natural day during which the sun is below the horizon; though the twilight, both in the morning and evening, is gometimes considered as forming part of the day. NIHIL DICIT, a failure in the defendant to put in an answer to the plaintiff’s declaration, &c. by the day assigned for that purpose. . - - NILOMETER, sometimes called Niloscope, an instrument used among the ancients to measure the height of the water in the river Nile, in its periodical overflowings. The measure of it was sixteen cubits, this being the height to which it must rise, in order to insure the fruitfulness of the country. NIMBUS, in Antiquity, a circle observed on certain medals, or round the head of some emperors, answering to the circles of glory drawn around the images of saints. - NIPPERS, certain pieces of cordage used to fasten the cable to the messenger, or voyal, in a ship of war, when the former is drawn into the ship by mechanical powers applied to the latter. They are usually six or eight feet in length, accord- ing to the size of the cable, and five or six of them are com- monly fastened about the cable and voyal at once ; those which are farthest aft are always taken off as the cable ap- proaches the main hatchway, and others are at the same time fastened on in the fore part of the ship, to supply their places, the boys of the ship receiving the ends to walk aft with them, and carrying them forward again when cast off from the cable. NIPPER Men, persons employed to bind the nippers about the cables and voyal, and to whom the boys return the nippers when they are taken off. Selvager NIPPERs are used, when from a very great strain the common nippers are not found sufficiently secure ; selvagers are then put on and held fast, by means of tree nails. NISI PRIUS, in Law, a commission directed to the judges of assize, empowering them to try all questions of fact issuing out of the courts of Westminster, that are then ready for trial by jury: the origin of which name is this: all causes commenced in the courts of Westminster-hall, are by course of the courts appointed to be tried on a day fixed in some Easter or Michael- mas term, by a jury returned from the county wherein the cause of action arises ; but with this proviso,-Nisi prius justi- ciarii ad assisas capiendas venerint ; that is, unless before the day prefixed, the judges of assize come into the county in question, which they always do in the vacation preceding each Easter and Michaelmas term, and there try the cause. And then, upon return of the verdict given by the jury to the court above, the judges there give judgment for the party to whom the verdict is found. - SNITRATES, compounds of nitric acid with the salifiable bases. NITRE, the common name of the nitrate of potash, which is known by the name of saltpetre, and is found in the East Indies, in Spain, the kingdom of Naples, and elsewhere, in consider. able quantities; but nitrate of lime is still more abundant. The greatest part of the nitre of commerce is produced by a combi- nation of circumstances which tend to compose and condense nitric acid. This acid appears to be produced in all situations. where animal matters are decomposed with access of air, and of propersubstances with which it can readily combine. Grounds frequently trodden by cattle and impregnated with their ex- crements, or the walls of inhabited places where putrid animal vapours abound, such as slaughter-houses, drains, or the like, afford nitre by long exposure to the air. Artificial nitre-beds. are made by an attention to the circumstances in which this Its taste is penetrating; but the salt is produced by nature. 'solving gold and platina. given out, an effervescence takes place, and the mixture ac- cold produced by placing the salt to dissolve in the mouth is such as at first to predominate over the real taste. Seven parts of water dissolve two of nitre, at the temperature of sixty de- grees; but boiling water dissolves its own weight, One hun- - dred parts of alcohol, at a heat of 176 degrees, dissolve only 2-9. On being exposed to a gentle heat, nitre fuses; and in this state being poured into moulds, so as to form little round cakes, or balls, it is called sal prunella or crystal mineral. Many kinds of plants, which grow in soils favourable to the produc- tion of it, contain nitre : this is particularly the case with pel- litory, borage, and the large sun-flower. Immense quantities of nitre are annually required for the purposes of war. From its constituting one of the most important substances in the composition of gun-powder, it has been found necessary to adopt artificial modes of procuring it. In several districts of the East Indies, there are certain places called saltpetre grounds. From these, large quantities of the earth are dug, and put into cavities through which water is passed. This brings away with it the salt that the earth contains, and this is afterwards sepa- rated from the water by boiling. It is extensively employed in metallurgy; it serves to promote the combustion of sulphur in fabricating its acid; it is used in dying ; it is added to common salt for preserving meat, to which it gives a red hue ; it is an ingredient in some frigorific mixtures, and it is prescribed in medicine as cooling, febrifuge, and diuretic ; and some have recommended it mixed with vinegar, as a very powerful reme- dy for sea scurvy. NITRIC Acid, is a compound of oxygen and azote, or nitro- gen, in the proportion of twenty-five parts, by weight, of the latter to seventy-five of the former. It is one of the constituent parts of nitre or saltpetre, which from hence has its name ; and, in a pure state, it is transparent and colourless, like water. By the action of light, however, it soon becomes yellow; and if exposed to the air, it emits yellow fumes, which even tinge the air of the same colour. To the taste it is extremely acid. It dyes the skin a yellow colour, which is very difficult to be removed, and is so corrosive as to destroy almost every sub- stance into which it penetrates. If poured upon oils, it sets them on fire. With various bases it forms the compounds called nitrates. This acid, which has hitherto newer otherwise been obtained than mixed with water, is chiefly known in commerce by the name of aqua-fortis. Its uses are various and import- ant. The mode of obtaining it, in large manufactories, is by distilling a mixture of nitre and clay; but the acid thus pro-s . cured being weak and impure, chemists, for nicer purposes, generally prepare it by distilling, in a glass apparatus, a pro- portion of three parts of nitre and one of spirit of vitriol. All kinds of metals are capable of being dissolved by nitric acid except gold and platina. For all practical purposes, nitric acid is obtained from nitrate of potash, from Which it is expelled by sulphuric acid; and it is of considerable use in the arts, being employed for etching on copper; as a solvent of tin to form with that metal a mordant for some of the finest dyes; in me- tallurgy and assaying; in various chemical processes, on ac- count of the facility with which it parts with oxygen and dis- solves metals; in medicine, as a tonic. and as a substitute for mercurial preparations in syphilis and affections of the liver : as also in the form of vapour, to destroy contagion in all cases of fever. For the purposes of the arts it is used in a diluted state, and contaminated with the sulphuric and muriatic acids, by the name of aquafortis. Two kinds are sold in the shops, double aquafortis, which is about half the strength of nitric acid; simple aquafortis, which is half the strength of the double. A compound made by mixing two parts of the nitric acid with one of muriatic, known formerly by the name of aqua regia, and now by that of nitro-muriatic acid, has the property of dis- On mixing the two acids heat is quires an orange colour. The aqua-regia does not oxydize gold and platinum, but causes their combination with chlorine. The nitrate of barytes, when perfectly pure, is in regular octahe- dral crystals, though it is sometimes obtained in small shining scales. It may be prepared by uniting barytes directly with nitric acid, or by decomposing the carbonate or sulphuret of barytes with this acid. Nitrate of strontian may be obtained in the same manner as that of barytes, with which it agrees in N O B N O M 723 DICTIONARY OF MECHANICAL SCIENCE. the shape of its crystals, and most of its properties. Applied to the wick of a candle, or added to burning alcohol, it gives a deep red colour to the flame. On this account it is useful in the art of pyrotechny and in exhibitions at public theatres. Nitrate of lime abounds in the mortar of old buildings, particu- larly those that have been much exposed to animal effluvia, or processes in which azote is set free. The nitrate of ammonia possesses the property of exploding, and, being totally decom: posed at the temperature of 600 deg.; whence it has acquired the name of nitrum flammans. NITROGEN, also called azote, a substance existing in great abundance, but is never found except in combination with some other body. Is a principal component part of the air which we breathe, which consists of 78 parts of nitrogen, and 22 of oxygen. It is accordingly here united with oxygen, and a certain portion of caloric and light. The nitrogen and oxygen of the atmospheric air may be separated, so that we may have the nitrogen by itself, but then only in a state of gas, and its properties are very different from those of the atmospheric air. Nitrogen gas will not support animal life. It is a little heavier than atmospheric air, elastic, and capable of expansion and condensation. It produces no change on vegetable colours, and, when mixed with lime water, does not make it milky, as does carbonic acid gas. Nitrogen gas and oxygen gas arti- ficially mixed in proportions in which air is found in the atmo- sphere, have exactly the same properties as atmospheric air, which they become in every respect. All animal and vegeta- ble substances contain a large portion of nitrogen. Different proportions of oxygen united with nitrogen produce compounds of very different properties: 78 parts of nitrogen and 22 of oxy- gen will produce atmospheric air. The same quantity of nitrogen with twice as much of oxygen make 100 of nitrous oxide. The same quantity of nitrogen and four times as much oxygen make nitric oxide. The same quantity still of nitrogen and eight times the quantity of oxygen, make nitrous acid. The same quantity of nitrogen, and ten times the quantity of oxy- gen, make nitric acid. Thus the only difference between at- mospheric air, so necessary to life, and nitric acid, which would destroy us if received internally, consists in this, that the latter contains ten times as much oxygen as the former. Nitrous oxide, a gas chiefly remarkable for its intoxicating effects when inhaled, affords at public lectures much amusement to the spectators. It is obtained by distilling nitrate of ammonia. Nitrous oxide and nitrous acid are not of much importance. Nitrogen combines with chlorine, and is then dangerously ex- plosive, and must be carefully and cautiously heated. It unites also with iodine. - * - NITROUS ACID, formerly called fuming nitrous acid, form a distinct genus of salts, that may be termed nitrites. NOBILITY, a quality that ennobles, and raises a person possessed of it above the rank of a commoner. The origin of nobility in Europe is referred to the Goths, who, after they had seized part of Europe, rewarded their chiefs with titles of ho- mour, to distinguish them from the common people. In Britain the term nobility is restrained to the degrees of dignity above knighthood; but every where else nobility, and gentility are the same. The British nobility consist only of five degrees, viz. duke, marquis, earl or count, viscount, and baron. In Britain these titles are conferred only by the king, and that by patent, in virtue of which it becomes hereditary. The privileges of the nobility are considerable, they are the king's hereditary counsellors, and are privileged from all arrests unless for trea- son, felony, breach of peace, condemnation in parliament, and contempt of the king. They enjoy their seats in the House of Peers by descent, and no act of parliament can pass, without their concurrence ; they are the supreme court of judicature, and even in criminal cases give their verdict upon their honour, without being put to their oath. In their absence, they are allowed a proxy to vote for them, and in all places of trust are permitted to constitute deputies, by reason of the necessity the law supposes them under, of attending the king's person; but no peer is to go out of the kingdom without the king's leave, and, when that is granted, he is to return with the king's writ, or forfeit goods and chattels. NOBLE, a money of account containing six shillings and eight pence. NQCTILUCA, a species of phosphorus. NOCTURNAL ARCH, in Astronomy, the arch of a circle described by the sun, or a star in the night. .* : * NocturnAi. Semi Arch of the Sun, is that portion of a circle he passes over between the lower part of our meridian, and the point of the horizon wherein he rises; or between the point of . horizon wherein he sets, and the lower part of our meri- la Il. * NoCTURNAL, or Nocturlabium, an instrument chiefly used at sea, to take the altitude or depression of some stars about the pole, in order to find the latitude and hour of the night. Some nocturnals are hemispheres or planispheres, on the plane of the equinoctial. Those commonly in use among seamen are two ; the one adapted to the polar star, and the first of the guards of the little bear; the other to the pole star, and the pointers of the great bear. This instrument consists of two circular plates applied to each other. The greater, which has a handle to hold the instru- ment, is about 2% inches diameter, and is divided into twelve parts, agreeing to the twelve months, and each month subdi- vided into every fifth day; and so as that the middle of the han- dle corresponds to that day of the year wherein the star here regarded has the same right ascension with the sun. If the in- Strument be fitted for two stars, the handle is made moveable. The upper left circle is divided into twenty-four equal parts for the twenty-four hours of the day, and each hour subdivided into quarters. These twenty-four hours are noted by twenty- four teeth, to be told in the night. Those at the hour twelve are distinguished by their length. In the centre of the two circu- lar plates is adjusted a long index, moveable upon the upper plate. And the three pieces, viz. the two circles and index, are joined by a rivet, which is pierced through the centre with a hole, through which the star is to be observed. To use the Nocturnal:—Turn the upper plate till the long tooth, marked twelve, be against the day of the month on the under plate : then bringing the instrument near the eye, suspend it by the handle with the plane nearly parallel to the equinoc- tial ; and viewing the pole star through the hole of the centre, turn the index about, till, by the edge coming from the centre, you see the bright star, or guard of the little bear, (if the instru- ment be fitted to the star); then that tooth of the upper circle, under the edge of the index, is at the hour of the night on the edge of the hour circle: which may be known without a light, by counting the teeth from the longest, which is for the hour twelve. - - NODE, in Surgery, a tumour arising on the bones. NODE, NO DUs, in the doctrine of Curves, is a small oval figure, made by the intersection of one branch of a curve with another. NoDE, in Dialing, denotes a small hole in the gnomon of a dial, which indicates the hour by its light, as the gnomon itself does by its shadow. § . NoDEs, in Astronomy, are the opposite points where the orbit of a planet crosses the ecliptic. Ascending NoDE, is that where the planet ascends from the south to the north side of the ecliptic, which is denoted by the character 82, and denominated dragon's head. Descending Nod E, is that where the planet descends from the north to the south side of the ecliptic, which is denoted by the character 8, and is called the dragon's tail. The right line joining these two points, is called the line of the nodes. It appears by obser- vation, that in all the planets the line of the nodes continually changes its place, its motion being in antecedentia, or con- trary to the order of the signs, the particular quantity for which, in each planet, will be found under their several names. NOLLE PROsequi, is used where the plaintiff will proceed no further in his action. NO-MAN’S-LAND, a space in midships, between the after part of the belfry and the fore part of a boat, when she is stowed upon the booms, as in a deep waisted vessel. NOMENCLATURE. The chemists of former times were unfortunate in the nomenclature which they adopted, there be- ing no regular system, and the names given to chemical sub- stances being frequently fanciful and often leading to error. In addition to this, chemists affected obscurity and mystery. To obviate these inconveniences, Lavoisier and the French che- 724 N O T N O N DICTIONARY C E MECHANICAL SCIENCE. mists proposed, and successfully introduced, a chemical momen- clature, of which the basis is simplicity, and which is intended as far as possible to convey an idea of the composition of the substance expressed. - - NoMENclAt URE, a catalogue of several of the most usual words in any language, with their significations, to facilitate the use of such words to those who are to learn the tongue. NONAGESIMAL DEG Ree, called also Mid Heaven, is the highest point, or 90th degree of the ecliptic, reckoned from it intersection with the horizon at any time. * NONAGON, a figure of nine angles and nine sides. The angle at the centre of a nonagon is 40°, the angle subtended by its sides 140°, and its area when the side is l = } nat. tang. 700 - 6 1818242. NONAPPEARANCE, a default in not appearing in a court of judicature. Attorneys subscribing warrants for appearing in court are liable to attachment and fine for nonappearance. If a defendant does not appear, and find bail upon a scire facias and rule given, judgment may be had against him. NON COMPOS MENTIS, in Law, denotes a person not being of sound memory and understanding. NON CLAIM, in Law, where a person has a demand upon another, and does not enforce his claim within a reasonable time, he is precluded by law from bringing his action to enforce it. Non claim is generally applied to the period of five years, after which a party is barred by a fine. NONCONFORMISTS, the same with dissenters, of whom there are numerous separate congregations in these kingdoms. NONES, NoNE, in the Roman calendar, the fifth day of January, February, April, June, August, September, Novem- ber, and December; and the seventh of March, May, July, and October, had six days in their mones; because these alone, in the ancient constitution of the year by Numa, had 31 days apiece, the rest having only 29, and February 30; but when Caesar reformed the year, and made other months containing 31 days, he did not allot them six days of nones. See CALEN- D A R. & NON EST FACTUM, a plea where an action is brought upon a bond, or any other deed, and the defendant denies it to be his deed whereon he is impleaded. In every case where the bond is void, the defendant may plead non est factum; but where a bond is voidable only, as the law terms it, he must shew the special matter. NoN Est INventus, signifies a sheriff’s return to a writ, that the defendant is not to be found. - NONIUS, or NUNEz, Peter, an eminent Portuguese mathe- matician and physician, was born at Alcazar, in Portugal, in 1497, and died in 1577, at the age of 80 years. From this author is derived the mame of the instrument called the monius, from his having described it in one of his works. The invention of it is, however, more commonly attributed to Ver- nier, by which name it is also sometimes called, and under which it is described in this work. NON-NATURALS, in Medicine, so called because by their abuse they become the causes of diseases. The old physicians divided the non-naturals into six classes, viz. the air, meats and drinks, sleep and watching, motion and rest, the passions of the mind, the retentions and excretions. NON-PROS, in Law, if the plaintiff neglects to deliver a declaration for two terms after the defendant appears, or is guilty of other delays or defaults against the rules of law in any subsequent stage of the action, he is adjudged not to pur- sue his remedy as he ought; and thereupon a non-suit or non- prosequitor is entered, and he is then said to be non-pros'd. NoN-Residence, in Ecclesiastical matters, is applied to those spiritual persons who are not resident, but absent themselves for the space of one month together, or two months at several times in one year, from their dignities or benefices, which is liable to the penalties, by the statute against non-residence, 21 Henry VIII. c. 13. But chaplains to the king, or other great persons mentioned in this statute, may be non-resident on their livings; as they are excused from residence whilst they atten those who retain them. - NONSUIT, in Law, is where a person has commenced an action, and, at the trial, fails in his evidence to support it, or has brought a wrong action. The plaintiff pays costs, but may bring another action for the same cause, which he cannot do after a verdict against him. NORIA, an hydraulic machine, common in Spain, which raises water. This engine consists of a vertical wheel of 20 feet diameter, on the circumference of which are fixed buckets, or boxes, for the purpose of raising water out of wells, &c. communicating with the canal below, and emptying it in a reservoir above, placed by the side of the wheel. The buckets have a lateral orifice, to receive and discharge the water. The axis of the wheel is embraced by four small beams, crossing each other at right angles, tapering at the extremities, and forming eight little arms. This wheel is near the centre of the horse-walk, contiguous to the vertical axis, into the top of which the top beam is fixed; but near the bottom it is em- braced by four little beams, forming eight arms, similar to those above described, on the axis of the water wheel. In the movement of the horse or mule, these horizontal arms acting as cogs, take hold, each in succession, of those arms, which are fixed on the axis of the water wheel, and keep it in rotation. This machine, nearly resembling the Persian wheel, throws up a great deal of water; but it has two defects: much of the water falls out of the buckets in their ascent, and a considerable portion of the water to be discharged falls into the reservoir just when the bucket is at its highest point of the circle. These inconveniences are both remedied by the Persian Wheel; which see. - - e . NORMA vel QUADRA EUCLIDIS, Euclid's Square, is a small constellation situated south of the Scorpion, and contains twelve stars, all below the fourth magnitude. NORMAL, a perpendicular forming with another line a right angle. - - NORMAN, a name given to a short wooden bar, thrust into one of the holes of the windlass in a merchantman, whereon to fasten the cable. It is only used when there is very little strain upon the cable. - NORTH, one of the four cardinal points. North-EAST PASSAGE. This navigation has been divided into three parts, and the advocates for it have endeavoured to shew that these three parts have been passed at different times, concluding from thence, that the whole taken collec- tively is practicable. These three parts are, 1. From Arch- angel to the river Lena ; 2. From the Lena round Tschukot- skoi Noss (or the north-eastern promontory of Asia) to Kam- schatka ; and 3. From Kamschatka to Japan. With respect to the first part, no one has ever asserted that it has been performed in one voyage. From an account of the several voyages that have been made in these seas, it appears that there is a cape between the rivers Chalanja and Piasida, that has never yet been doubled. As to the second division, it has been affirmed, that a passage has been effected by several ves. sels which have at different times sailed round the northern extremity of Asia. But from the Russian accounts it is inferred, that it has been performed but once, viz. by one 1)eshneff, who, in 1648, is said to have doubled this formidable cape. Of the third, or remaining part, of this passage, no doubt can be entertained. The connexion between the seas of Kamschatka and Japan has been established by many voyages. North-West Passage, by Hudson's or Baffin's bay, into the Pacific ocean. , , , , , NORTHERN SIGNs, are those that are on the north side of the equator viz, Aries, Taurus, Gemini, Cancer, Leo, and Virgo. º - NORTHING, in Navigation, is the difference of latitude which a ship makes in sailing towards the north. - NOSTOCK, the name of a vegetable substance, of a greenish colour, partly transparent, and of a very irregular figure. It trembles at the touch, like jelly, but does not melt like that. It is found in all, but most frequently in sandy soils, usually after rain in summer. . . . . - NOTARIAL Acts, are those acts in the civil law, which re- quire to be done under the seal of a notary, and are admitted as evidence in foreign courts. - - NOTARY, in Law, is a person duly appointed to attest deeds and writings; he also protests and notes foreign and inland bills of exchange and promissory notes, translates languages, and attests the same, enters and extends ship's protests, &c. y p y N O T N O T 725 DICTIONARY OF MECHANICAL SCIENCE. NOTATION, in Arithmetic, the method of expressing, by means of certain characters, any proposed quantity. In the modern analysis, notation implies a method of representing any operation, and the judicious selection of proper symbols for this purpose is an important consideration, which every author who undertakes to write on this subject should particu- larly attend to. In the common scale of notation every num- her is expressed by means of the ten characters, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, by giving to each digit a local as well as its pro- per or natural value, the discovery of which was perhaps one of the most important steps that has ever been made in mathe- matics, and does as much honour to its inventor as any other in the history of this science. With regard to the characters or digits, by which numbers are at this date universally expressed, they seem to be the same, with a very slight alteration, as those that were originally employed for that purpose; but their forms are not such as to indicate their origin, though some authors have discovered more ingenuity than judgment, by endeavouring to trace them to the Greek alphabet, and hence | inferring, contrary to every evidence, a Grecian origin to our present system of notation. See the different arithmetical characters in the following engraving * I a uſ aſ G. L. A 8 9 I p w S. ſſ (/ V A q 10 / / /a/ S. B (/ v A # // / 2, 3 & 6 6 A & 9 ſo / 7. 3 & 4, 6 A & 9 AO 2 z & 9 y 3 9 a 6 4 NotAtion of the Hebrews, resembled, in a great measure, that of the Greeks above described ; thus, Instead of our units,. . . . . . . . . . . . . . 1, 2, 3, 4, 5, 6, 7, 8, 9, The Hebrews used their letters, .... N, n, l, n, n, l, 1, n, to. For our tens, as . . . . . . . . . . . . tº e s e º e 10,20,30,40,50,60,70,80,90, They employed . . . . . . . * e º e s e o a ... ', P, 2, p. 2, D, V, B, *. For the hundreds they used . . . . . . . p, n, w, n, T, D, J, F, Y. And for representing thousands, they had again recourse to their simple units, distinguishing them only by two dots, or acute accents, thus n, or 8, expressed 1000; n 2000; 10000, and so on. Not Ation of the Greeks. These people had three distinct notations; the most simple of which was, by making the letters of their alphabet the representatives of numbers, a, 1 ; 3, 2; y, 3; and so on. Another method was by means of six capital letters, thus, Iſua for uta) 1; II ſtrevrs]'6: A[Öska] 10; H [Hekarov) 100; x [xi\ta] 1000; MTuvstal 10000; and when the letter II enclosed any of these, except I, it indicated the enclosed letter to be five times its proper value, as stated above ; thus, # |Ai represented 50; [H] 500; |X| 5000, and so on. This notation was only used to represent dates and similar cases; for arith- metical purposes they had a more organized system, in which thirty-six characters were employed, and by these any number not exceeding 100000000, might be expressed, though in the first instance it appears that 10000, or a myriad, was the extent of their arithmetic. - Our digits, . . . . . . . . . . . . . . . tº 0 e º e º e They expressed by the letters .... a, 3, Y, 3, s, c, &, m, 0. For our tens, as . . . . . . . © e º 'º e a tº e e 10,20,30,40,50,60,70, 80,90, They employed the letters ... ... , t, k, A, u, v, #, o, ºr, The hundreds were expressed by... p, o, r, v, q, x, y, w, 2. And the thousands by . . . . . . . . . . . a, 8, Y, Ö, e, c, &, n, J f f & Af p M f That is, they had recourse again to the characters of the simple units, which were distinguished by a small iota or dash placed below them; and with these characters a number under 10000 was readily expressed; and this, as we have 74. 1, 2, 3, 4, 5, 6, 7, 8, 9, observed above, was, for some time, the limit of their arithme- tic. Afterwards 10000, or a myriad, was represented by M., and any number of myriads by M placed under the number of them. Thus, CZ 3 y M. M. M. represented 10000 20000 130000, &c. NotATION of the Romans. This is still employed by us for dates and other similar purposes, and is too well known to require a very minute description. The Roman numerical cha- racters are seven in number; viz. I. one; W. five ; X. ten ; L. fifty; C. a hundred ; D, or IQ. five hundred; M. one thousand; this last number is also sometimes expressed by DCI, or by CIO. And by the various combinations of these characters, j number whatever might be expressed, as in the following table :- 1 = I. 2 = II. $ As often as any character is repeated, 3 = III. & so many times is its value repeated. 4 - IV } A less character before a greater, dimin- T * ' ' ' ishes its value by the less quantity. 5 - V. 6 — VI } A less character after a greater, in- - & creases its value by the less quantity. 7 - VII. - 8 - VIII. 9 – IX. 10 – X. I 1 - XI. 40 = XL. 50 = L. 60 – LX. 100 – C. - - tº For every O added, this becomes 500 = D. or IO. łe. times as much. y tºº For every CO, set one at each end, 1000 = M. or CIO. } this becomes ten times as much. *mºnº == ( A line over any figure increases it 5000 = I00, or v.; 1000 fold. y Dig 6000 = VI. 10000 = X. or CCIOO. 50000 = IOOO. 60000 = LX. - 100000 = M or CCCIOOO. 1000000 = MM. or CCCCIOOOO. NotATION, in Music, the manner of expressing or represent- ing by characters, all the different sounds used in music. NOTE, a minute or short writing containing some article of business; in which sense we say promissory note, note of hand, bank note, &c. . * - NoTE, Bank, The paper currency of any bank, as of the Bank of England, that of Scotland or Ireland, or of any pro- Vincial or private bank.—This currency is known as bank- paper, or bank-note, and this note is usually printed on a par- ticular sort of paper, from an engraved plate. The consider- ation of every such engraving, but for the sake of alphabetical reference, would in this Dictionary belong to the word engrav- ing or printing : it falls most naturally under the word NoTE. But as preliminary explanations, we shall here define accurately the two species of engraving that have been heretofore employed in printing bank-notes:—First, then, there is employed engrav- ing in Creuz, or copper-plate engraving, where the line or figure intended to be printed is cut down into the copper. This line, in printing, is filled with the ink, and the intermediate surface being cleaned off after the plate has been charged, contains of course no ink, and leaves the paper white. This mode of printing is called copper-plate printing. Secondly, engraving in Relief, wherein the lines or figures, intended to be printed on the paper, are left standing on the plate, the inter- mediate parts being cut away. In this case, which is exactly the converse of the former, the ink is applied to the surface only of those raised lines or figures, and from them it is trans- ferred to the paper; the intermediate excavated parts con- taining no ink, and therefore leaving the paper white. This mode § printing is called surface printing, and is the same as 8 726 N O T N O T DICTIONARY OF MECHANICAL SCIENCE. type, stereotype, or letter-press printing. It is also called wood- cut or block-printing, , because all engravings in wood are . printed from the surface, i.e. the relief. Hence, to produce a white line or figure on a black ground from copper-plate print- ing, the line or figure must be raised; while to produce the same by surface or relief printing, the line or figure must be sunk, and the contrary, as to the black line; for, that which produces the black line in one case, produces the white line in the other, and consequently, as it is evidently more difficult to produce the raised work or cameo, than the sunk work or intaglio, so the white line, which is the most difficult to produce in copper-plate printing, is the most easy in surface printing ; while the black line, which it is easy to produce in copper-plate printing, is difficult in surface printing: in short, that which is difficult in either case, is easy in the other; so that where these respective styles can be interchanged and mixed by separate impressions, there is no difficulty in the production either of the white or the black line, how complicated Soever may be the figure. Any bank-note therefore, printed from the combi- nation of these two modes of engraving, and at two separate impressions, may be accurately imitated, and the public de- ceived by a false security. Now, then, the great means to be accomplished in securing the paper currency, is, to discover a mode of producing some effect in paper, which can only be imitated by the same process as that by which the original note is created, so that the forger shall be compelled to encoun- ter all the difficulties of the original in his attempts at imita- tion. We have only seen one plan that possesses this most essential property, and this plan is the Patent Compound Plate, for printing in two or more colours at one impression, which, with a delicacy and variety in the colouring and workmanship that belong exclusively to this invention, certainly offers the most simple test of genuineness to the public. Indeed, such are the variety and capability of this plan of engraving and printing, that it fails within the power of fewer persons to imi- tate, than any other known branch of the graphic art appli- cable to bank-notes. The Specimen Plate which Messrs. Whiting, and Branston have executed for this Dictionary, reduces the question of security against forgery to two immediate objects:–First, it proves that the means of real security in bank-notes do exist, and it is therefore calculated to promote general confidence (against forgery) in the bank-notes executed by Messrs. Whit- ing and Branston. Secondly, it shews in what way the true principles of protection may be extended to every branch of the paper currency of Great Britain and Ireland, to the pro- vincial paper as well as that of the Bank of England, without either of these branches interfering with or diminishing the security of the other. * . It is true, that there is nothing new in printing in two colours, or even in all the colours of the rainbow ; the former has been practised by ordinary means for many years in the lottery shares and bills, and in title-pages, &c.; the latter is adopted daily, in printing calicoes, paper-hangings, oil-cloths, &c. It is not presumed, therefore, to appropriate this branch of art exclusively to the security of bank-notes; still, however, we may look to certain peculiarly refined applications of it for the accomplishment of that object; and as there is no real security against forgery to be achieved in one colour, it must consequently be sought for in the combination of two or more colours; and, indeed, the extension of field thus obtained for the exercise of variety, ingenuity of combination, and difficulty of execution, especially in printing, will be found utterly to defy imitation by any of the ordinary modes of printing in two colours. . . These details “Analysis of the true Principles of Security against Forgery,” inscribed to the Earl of Liverpool. The public are already in possession of a small volume which Sir William published on the protection of the metallic currency. missioners of inquiry as to the best means of preventing for- gery, Sir William: Congreve employed Mr. Branston to imi- tate, in wood and copper engravings, portions of the notes which the American artists presented to the Bank of England as inimitable, or which, at least, would take years of the forger's time to imitate. Now, five heads of a Homer, which we derive from Sir William Congreve's As one of the com— the American artists engraved on copper in three months, Mr. Branston, senior, cut in wood in four days, and an exact copy too from which five fac-simile heads of the Grecian bard were printed precisely similar to the American artists’ Homers. A portion of fine writing in eight small ovals, being part of the Bank Charter, and containing 20,000 letters, occupied the American artists six months. Mr. Branston, senior, who had never written on copper before, engraved or wrote these 20,000 let- ters in six days, and had them stereotyped. They are invisible to the naked eye; but are perfectly distinct with a magnifying glass of high power. But the Bank Charter thus engraved, and having the merit of being perfectly illegible in both the American original and Mr. Branston's copy, is no security against forgery. This trumpery piece of fine writing is a piece of idle labour, on the part of the American artists. Then, again, in the American inimitable, there is a border engraved with a geometrical lathe, to which is attributed the power of free will, and a little of that perverseness which sometimes accompanies the exercise of that power, inasmuch as, it is broadly stated by the Transatlantic volume, (page 27,) “that it is not to be made (adjusted) to produce the same pattern twice l” The volume before us, speaks of “the im- possibility of doing this work with the graving tool,” and it occupied thirty months; yet Mr. Branston, junior, then only eighteen years of age, imitated it in five days. Some female heads on the same note, that occupied another American artist about two months, were cut in wood by Mr. Branston in two days. This American note is now before us. It contains five heads of a Homer, engraved by Mr. Perkins the younger; four female heads, engraved by Colonel Farman; two pieces of border, produced by the geometrical lathe, resembling the volutes of a certain number of lines, like the twine and strands of a cable, more or less twisted, and perfectly shewn in the Plate of my own Dictionary, and either drawn out straight, or bent into coils. Inlaid in the borders thus produced, are eight fac-simile ovals, containing part of the Bank Charter, perfectly illegible without the aid of a high magnifying glass. And the time which the American writers estimate it would cost the forger to imitate this note, is three years and ten months. AII which was imitated excellently enough for the use of any forger, by the Branstons, father and son, in seventeen days, and by hand too, without the aid of machinery. There is another note, which though suppressed in the printed volume of the American artists, is the sixth specimen in Sir William Congreve’s work, and which, according to the estimate of its fabricators, would take the forger five years; but which Mr. Branston, his son, and a second-rate engraver, imitated per- fectly in thirty-three days, and by hand, without the aid of machinery. - - - - Having thus briefly noticed the facility with which the most elaborately engraved bank-notes may be imitated, we come now to describe the Compound Patent Plate, the particular appli- cation of which to Bank of England notes, in one or two parti- culars, we shall not, of course for obvious reasons, venture to describe. Though this plate is compound, its operation by a simultaneous impression is entirely different from that which the Bank employs, not only as to the mode in which the effect is produced, but also as to its manner of effecting the security of the note. In fact, the particular effect of printing in colours, selected for a portion of the security of the Bank of England note, cannot be imitated by the Compound Plate, while the characteristic work of the Compound Plate cannot be pro- duced by separate impressions; so that no use of the latter, however public, could tend, in the least, to facilitate the imita- tion of the former. It is evident, therefore, that although the general principle of printing in colours is found to be the best means of security against forgery, still there is a sufficient variety to be derived from this general principle, not only for the protection of the notes of the Bank of England, but for those also of the Country Banks, without either invalidating the other. The Bank of England may, therefore, specify the peculiar system of the combination of colours, which they have adopted, as part of their security; and they may confine this \ . to themselves by a protecting act of parliament, without at all interfering with the peculiar security of the Compound Plate; and this latter plan of printing in two or more colours, may ±3ēſ. } ! %| ſae - ±|- £&& - - º () ， } |- |- - -- º: N- - %/№ſae %$§！： -- --> - --------------- <<<<<：：::：:：：: }|º. ： ---> --- - --- } -> ------ - - - -|- （……………" ！！！！！------- №. - --~ Sº- --> - -- > - - --- -> º- - - Sº - > -- -> -> --~~~ -- -- №<■ -------------------------|------------- --- ！！！（ №ae, =====~：： - > - ±，-- ---№ae， ·---···---···---···---···---···------ |-………-！----·---···---···---···|-№ N O V DICTIONARY SCIENCE. N U C 727 OF MECHANICAL also be secured to the other branches of the Paper Currency, without the least effect upon the protection of parliament granted to the Bank of England Note. - It has been already observed, that the Compound Plate is in fact the application of certain principles illustrated by Sir William Congrove in his book on the Metallic Currency, not to be counterfeited without immediate detection. It is curious to observe the applicability of these same principles to the secu- rity both of coin and paper currency. That which is the coin in the one case, becomes the plate for the printing from in the other; and the delicate and perfect union of colours, which will be found to be thus effected on the paper, produces a similar, though not so positive a test of originality, by its coincidence and adaptation, as that which the union of the metals them- selves gives in the coin: but this will be better understood by d the sequel. These plates are made of two metals, of which one must be of brass, copper, or other metal at least as strong. The design is first drawn on the brass plate ; the parts in which it is intended to introduce the second colour, are then cut out in the most delicate filigree. A second plate is then combined with the first, by a process peculiar to this sort of workman- ship, the parts of which are fitted most accurately into all the interstices of the brass plate ;' and, indeed, the fineness of the filigree is by hypothesis such, that the combination can only be formed by this peculiar mode of uniting the two metal plates, which are then engraved as one ; and for printing, they are fixed in a press of peculiar construction, so that they may be separated to receive a different coloured ink on each plate, and unite again to print whatever work may be engraved, or other- wise placed upon them, in two colours at one impression. Thus, in the Specimen Plate before us, all those parts of the engraving which bear the red colour, as my own name, that of the publisher, and the various crescents or devices, may be considered the second colour workmanship cut out in filigree in the first plate, while the black ground exhibits the second plate combined with the first. By this means, the most beau- tiful and delicate junction of colour is effected. The ſinest lines, though formed of various portions of different colours, flow as perfect as if produced in one colour by the stroke of an indivisible plate; a single point may be found of the two colours in perfect union; and the most beautiful and correct adaptations of colour and complicated variety of forms may be made, so as utterly to defy imitation by any of the ordinary processes of printing in two colours. In fact, if sufficient art be resorted to, in combining this tissue Öf extremely nice and delicate colour over the whole surface of the Compound Plate, it is evident, the whole of the work on the note must be pro- duced by one simultaneous operation of the forger, and can- not, like the American note, be imitated in any way that pro- ceeds by a repetition of impressions. We have only in conclusion to add, that we will give one hun- dred guineas to any artist who, by two impressions of printing in two colours, shall produce the fellow of Whiting and Bran- ston's Compound Plate, as engraved and printed for Dr. Jamieson's Dictionary of Mechanical Science. NOTES, in Music, are characters which by their various forms and situation on the staves, indicate the duration as well as the gravity or acuteness of the several sounds of a compo- sition. - - NOT GUILTY, the general issue or plea of a defendant, in a criminal action or prosecution; as also in an action of tres- pass, or upon the case for deceits and wrongs. ‘’. NOTICE, in Law, is the making something known of which a man was or might be ignorant before, and it produces divers effects. - NOUN, in Grammar, a part of speech which signifies things without any relation to time; as a man, &c. NOVEL, in the Civil Law, a term used for the constitution of several emperors, as of Justin, Tiberius, Leo, and more par- ticularly for that of Justinian. - Novel Assignment, or New Assignment, a term in law plead- ings. In actions of trespass, where the form of the declaration being very general, the defendant pleads in bar a common jus- tification; to which the plaintiff replies by stating, that he brought his action as well for a certain other trespass which he states with more particularity, as for that which is justified,— this is called a new assignment. NOVEMBER, the eleventh month in the Julian year, but the ninth in the year of Romulus, beginning with March, whence its name. In this month, which contains thirty days, the sun enters the sign Sagittarius t, usually about the twenty- first day of the month. The Kalendar of Animated Nature for November, round London, informs us, that the buck grunts, the golden plover appears, snails and slugs bury themselves, greenfinches, flock, the winter moth and the common flat-body moth appear in gardens about the end of the month. That of Vegetable Nature, shews a few accidental annual plants in flower, according to the temperature of the season. The laurustinus and the calicanthus praecox are in flower, as are soine primroses. - . In the Kitchen Garden, are sown short-topped radishes on a warm border, and pease and beans; celery, endive, artichoke, and seakale, are protected; potatoes left in the ground, are taken up as wanted. Outstanding edible roots are covered with litter or leaves; cauliflowers by hoops and mats.-Peren- nials are propagated, and any thing to be transplanted, and that has been omitted in October, must now be removed. In Routine Culture, all operations on the earth, excepting digging and trenching, must be performed only in dry wea- ther. Dress artichoke and asparagus beds; take up endive, broccoli, and cauliflower, and Iay them flat in dry ground. Weed all seedhing crops. Dig, trench, and maliure. T)estroy insects, and fill the icehouse if you can. . * * In the Hardy Fruit Department, plant trees in dry weather, stake and mulch both root and stem, especially tall standards of the pithy wooded sorts. Prune vines, dig, dress, and prune hardy fruit trees: the nectarine, peach, and apricot, should be deferred till spring. Examine the fruit room, and clear it of all decaying fruits. - In the Culinary Hot-house Department, glass-case without artificial heat, sow small salads, and pease and beans, to trans- plant or remain. Attend to air, and removing decayed leaves. Transplant lettuces from the cold frames, to force them for- ward ; begin to force asparagus, and build mushroom-beds. In the Flower Garden open ground Department, plant dried roots of border flowers; transplant biennials, if the weather is fine ; protect tender roots by litter and leaves, or tan and ashes. Land up trees with mats or straw, covered with nets. In the routine culture, collect earths, composts, and manures. - In the Flower Garden Hot-house Department, glass-case with- out artificial heat; take care of alpines, annuals, and peren- nials intended for forcing. Guard against damps by excluding air charged with heavy moisture. In the hot-beds and pits, go on forcing all manner of flowering shrubs, bulbs, and perennial plants. Blow Dutch roots in water glasses. In the green- house, the temperature must be 42° at a medium. In the dry stove, the temperature should be 45° or 50° at a maximum. In the bark and moist stove, from 55° to 70° at a maximum. In the Pleasure Ground and Shrubbery, plant deciduous trees and shrubs of the hardier kind in dry weather; prune and cut hedges; protect magnolias, Chinese rose-trees; roll, mow, and sweep turf. Prepare for planting, by levelling, digging, trenching, &c. - - - In the Nursery Department, fruit trees must be planted only in mild weather; after the middle of November, it is not pro- per to meddle with fruit trees till February. Ornamental trees | and shrubs may now be planted; the larger seeds of forest trees may be sown: cones, acorns, masts, nuts, keys, and ber- ries for immediate sowings, may now be gathered. Permanent Plantations and Park Scenery trees should now be planted in temperate weather; deciduous trees should be pruned, thinned, or felled, according to circumstances. Dead fences of every description, repair or erect; but never build walls in December or January. NUCLEUS, the Kernel, is used by Hevelius, and some other astronomers, for the body of a comet, which others call its head, as distinguished from the tail or beard. Nucleus is also used by some writers for the central parts of the earth and other planets, which they suppose firmer, and separated from the other parts, as the kernel of a nut is from the shell. . 728 N U M N U M Diction ARY OF MECHANICAL SCIENCE. * © NUDE CONTRACT, Nudum Pactum, a bare promise with- out any consideration. NUISANCE, any thing that does hurt, inconvenience, or damage, to the property or person of another. Nuisances are either public or private, as they affect either the public or the in- dividual. The remedy for a private nuisance is by action on the case for damages, and for a public nuisance by indictment. Amongst the nuisances of most common occurrence are the erecting of noxious manufactures in towns, and in the vicinity of ancient houses ; as a vitriol manufactory, to the annoyance of the neighbours in general. Disorderly houses, stage booths, lotteries, and common scolds, are also public nuisances. Where the injury is merely to an individual, and not to the public, the 'individual only has an action, but not in the case of a public nuisance, where the private injury is merged in that of the pub- lic, but where an individual receives a particular injury by a public nuisance. And any one aggrieved may abate, that is, pull down and remove a nuisance, after which he can have no action; but this is a dangerous attempt, to take the law into one's own hands. It must be done without riot, if at all. Eve- ry continuance of a nuisance is a fresh nuisance, and a fresh action will lie. NUL TIEL RECORD, the replication which the plaintiff’ makes to the defendant, when the latter pleads a matter of record in bar to the action, and it is necessary to deny the ex- istence of such record. NUMBER, in its extended signification, has reference to every abstract quantity that can be made the subject of arith- metical computation; but, in a more limited sense, it signifies only several things of the same kind, and may be defined a multitude of units. Numbers of this latter kind are termed integral, to distinguish them from other numbers, of various denominations; as experimental, fractional, &c. Integral NUMBERs are distinguished into various classes, as follows: Absolute, Abstract, Abundant, Amicable, Cardinal, Circular, Composite, Concrete, Figurate, Homogeneal, Irra- tional, Ordinal, Perfect, Polygonal, Prime, Rational, &c. The Properties of NUMBERs, are certain theorems relating to their Divisors, Forms, Powers, Products, &c. of which the more general are enumerated below ;-1. The product of two numbers is the same, whichever of the two is the multiplier. 2. Every integer number, without exception, is composed of, and may be resolved into, different terms of the geometrical series 1, 2, 4, 8, 16, &c. 3. Every integer number, without ex- ception, may be made up by the addition and subtraction of different terms in the series of 1, 3, 9, 27, 81, &c.; and there- fore with such a series of weights, any number of pounds may be ascertained. 4. The difference between any cube and its root, is divisible by 6; between any fifth power and its root, is divisible by 10. 5. Every number whatever is the sum of three, or a less number of triangular numbers; of four, or a less number of squares; of five, or a less number of pentagonals; and so on for hexagonals, heptagonals, &c. This theorem has never yet been demonstrated generally. - Golden NUMBek. See GoLDEN Number and CYCLE. NUMBER of Direction, in Chronology, some one of the 35 numbers between the Easter limits, or between the earliest and latest days on which Easter can fall, viz. between March 22 and April 25, which is 35 days, and is so called because it serves as a direction for finding Easter for any year, being the number that expresses how many days after the 21st of March Easter-day falls. Thus, Easter-day, falling as in the first line below, the number of direction will be as on the lower line. March. * 2– - -N- —) Easter-day,. . . . . . . . . . . . . . . . . . 22,23,24,25,26,27,28,29,30,31 Number of direction, . . . . . . . . , 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 April. A. - /- Easter-day, . . . . . . . . . . . . . . . . . . 1, 2, 3, 4, 5, 6, 7, 8, &c. Number of direction, ........ , 11,12,13,14,15,16,17,18, &c. and so on, till the number of direction on the lower line be 35, which will answer to April 25, being the latest that Easter can happen. Therefore add 21 to the number of direction, and the sum will be so many days in March for the Easter-day; if the sum exceed 31, the access will be the day in April. To find the Number of Direction.—Enter the following table with the Dominical Letter on the top, and the Golden Number on the right hand; then where the columns meet is the number of direction required for that year. - G. N. A B | c | D | E | F | G 29 27 8 19 30 12 13 7 8 9 10 11 26 27 28 29 30 31 32 10 19 20 21 15 T 16 17 18 I 24 25 2 19 lº 14 15 16 17 I8 3 5 6 7 8 . 2 3 || 4 4. 26 27 21 22 || 23 24 25 5 12 13 14 15 16 10 T1 6 33 34 35 , 29 30 31 32 7 19 20 21 22 23 24 18 8 9 11 5 6 7 8 9 10 || 4 12 26 27 28 29 23 24 25 13 12 13 14 15 16 17 18 14 5 6 7 l 2 3 4 15 26 20 21 22 23 24 25 I6 12 13 14 15 9 10 11 17 33 34 28 29 30 31 32 18 19 20 21 22 23 17 18 , 19 I2 6 7 8 9 l() 11 Thus, for the year 1790, the Dominical Letter being C, and the Golden Number 5; in the column C and the line 5 stands 14, the number of direction; to this add 21, which 'gives 35, subtract 31, and there remains 4; which is the day of April on which Easter-day fell in the year 1790. NUMBeR, in Grammar, a modification of nouns, verbs, &c. to accommodate them to the varieties in their objects, considered with regard to number. NUMBERs, in Poetry, Oratory, Music, &c. are certain mea- sures, proportions, or cadences, which render a verse, period, or song agreeable to the ear. NUMERAL FIGUREs, or Digits, are those figures by which all numbers are expressed in arithmetic. See NoTATION. NUMeRAL Letters are the seven Roman capitals I. V. X. L. C. D. M. See NoTATION of the Romans. NUMERATION, in Arithmetic, is the art of reading, or estimating, the value of any number expressed by the ten characters 1, 2, 3, &c. anyhow combined or repeated ; and is, therefore, the reverse of notation, which is expressing by those characters any number proposed. In order that the nine signi- ficant figures may express not only units, but tens, hundreds, thousands, &c. each character has a local value given to it, so that, though when alone they express only units, yet in the second place they denote tens; in the third, hundreds; in the fourth, thousands: thus, 5555 represents five thousands, five hundreds, fifty, and five. Hence, then, to express any written number, or to assign the proper value to each character, beginning at the right hand, divide the proposed number into periods of three places each, and consider two of these as form- ing one period of six places; then each of these greater periods has a name common to all the figures of which it is composed ; the first six being units; the next six, millions; the third, mil- lions of millions, or billions; the fourth, trillions; and so on : also every half period of three places is read separately, or by itself, so many hundreds, tens, and units; only after the left- hand half of each period, the word thousands is repeated; and at the end of each complete period its common name is added ; Thus, 4,591, is four thousand, five hundred and ninety- OITC, 346,718, is three hundred and forty-six thousand, seven hundred and eighteen. 47,671,600, is forty-seven million, six hundred and g seventy-one thousand, six hundred. 7,418,467,600,000, is seven billion, four hundred and eighteen - thousand, four hundred and sixty-seven - million, six hundred thousand. The French enumerate their numbers in a different manner, N U T * N Y M 729 DICTIONARY OF MECHANICAL SCIENCE, * calling the first three, hundreds and units; the next three, thousands; the next three, millions; the next three, billions, the next three, trillions, &c. NUMERATION, or Notation, the art of expressing in characters any number proposed in words; or of expressing in words any number proposed in characters. - NUMERAtoR of a Fraction, that number which stands above the line, and shews how many parts the fraction consists of ; as the denominator represents the number of parts into which the unit is supposed to be divided. - NUMERICAL, or NUM ERAL, something that relates to number.—Numeral Algebra, are those cases in which numbers are employed, in contradistinction to Literal Algebra, or that in which the letters of the alphabet are made use of. NUMIDA, the Pintado or Guinea Hen, in Natural History, a genus of birds of the order gallinae, whose native territory is Africa. It is gregarious, having been often seen in numerous flocks, but now extremely common in this country. The female lays many eggs, and secreting her nest, sometimes will sud- denly appear with a family of twenty young ones. It is a bird of harsh soupd, which it almost perpetually utters. The flesh of the young birds is valued, and its eggs are thought prefer- able to those of the common hen. NUNCIO, or NUNTIo, an ambassador from the pope to some Catholic prince or state. NUNCUPATIVE WILL, denotes a last will or testament, only verbally, and not in writing. - NUPHAR, in Botany, is the yellow water lily, from the flowers of which was anciently prepared a cooling drink. The Turks still make sherbet from these flowers, which give a kind of bitter-almond ſlavour to the liquor in which they are infused. Class Polyandria, order Monogynia. NURSERY, a piece of land for raising and propagating trees and plants to supply the garden and othcr plantations. In a nursery for fruit trees, the following rules are to be ob- served. 1. That the soil should not be better than that in which the trees are to be planted, when removed. 2. It is highly ne- cessary that it be fresh. 3. It ought neither be too wet, nor too dry, but rather of a middling mature, though of the extremes dry is preferred. 4. It must be enclosed in such a manner that neither cattle nor vermin may come in ; and to exclude hares and rabbits. 5. The ground being enclosed, should be care- fully trenched two feet deep, in August. In trenching the ground, cleanse it from the roots of all noxious weeds. 6. The season being come for planting, level down the trenches about the beginning of October, and then lay out the ground into quarters, which may be laid out in beds for a seminary, in which you may sow the seeds or stones of fruit. 7. And hav- ing provided yourself with stocks, the next year proceed to transplant them: draw a line across the ground, and open a number of trenches exactly straight; then take the stocks out of the seed-beds; in doing which you should raise the ground with a spade, in order to preserve the roots as entire as possi- ble; prune off the very small fibres; and if there are any that have a tendency to root directly downwards, such roots should be shortened. Then plant them in the trenches, if they are de- signed for standards, in rows three feet and a half or four feet from each other, and a foot and a half distant in rows ; but if for dwarfs, three feet row from row, and one foot in the row, will be a sufficient distance. These plants should not be head- ed or pruned at top. If the winter should prove very cold, lay some mulch on the surface of the ground near their roots, taking care not to let it lie too thick near the stems of the plants, and to remove it as soon as the frost is over. In the summer sea- son destroy the weeds, and dig up the ground every spring between the rows. See GRAFT ING. As to timber trees, nurseries should be made upon the ground intended for planting, where a sufficient number of the trees may be left standing, after the others have been drawn out to plant in other places. NUT, in Vegetable Physiology, is a hard and bony seed, not opening by valves, but usually consisting of one cell and kernel. - NUTATION, in Astronomy, is a tremulous motion of the earth’s axis, through which its inclination to the plane of the ecliptic undergoes some changes. This phenomenon was first observed by Dr. Bradley, who published an account of his 75. discovery in 1717. The period of these variations is nine years. - NUTGALLS, are excrescences formed on leaves of the oak by the puncture of an insect, which deposits an egg on them. The best are the Aleppo galls of commerce, imported for the use of dyers, calico printers, &c. - • , - NUTMEG, the kernel of a large fruit, not unlike the peach, the produce of the MIRISTICA, which see. The nutmeg is sepa- rated from its investient coat, the mace, before it appears in commerce. The nutmeg, as we receive it, is of a roundish or oval figure, of a tolerably compact and firm texture, but easily cut with a knife, and falling to pieces on a smart blow. Its sur- face is not smooth, but furrowed yith a number of wrinkles, running in various directions, though principally longitudi- mally. It is of a greyish brown colour on the outside, and of a beautiful variegated hue within. It is very unctuous and fatty to the touch when powdered, of an extremely agree- able smell, and of an aromatic taste, without the heat that at- tends that kind of ſlavour in most of the other species. The largest, heaviest, and most unctuous are to be preferred, such as are the shape of an olive, and of the most fragrant smell. NUX VOMICA, the seed of the officinal strychnos, a native of the East Indies. It is about an inch broad, and nearly a quarter of an inch thick, covered with a kind of woolly matter; internally it is tough and hard, like horn, to the taste extremely bitter, but having no remarkable smell ; it consists chiefly of a gummy matter, the resinous part being very inconsiderable. Nux vomica, reckoned amongst the most powerful poisons of the narcotic kind, proves fatal to dogs in a very short time. Loureiro relates that a horse died in a quarter of an hour after taking an infusion in wine of the seeds in a half-roasted state. It is employed to stupify fishes in a fish pond, when they come to the surface and are easily taken. NYMPH, among naturalists, that state of winged insects between their living in the form of a worm and their appearing in the winged or most perfect state. NYL GHAU, in Zöology, an animal between the deer and the ox, swift of foot, and remarkably strong. The first pair were sent from Bombay to England in the year 1767, as a pre- sent to Lord Clive. NYMPHAEA, WATER LILY, a genus of the polyandria mo- nogynia class and order, of which there are six species: 1. and 2. The lutea and alba, or yellow and white water lilies ; na- tives of Britain, growing in lakes and ditches. Linnaeus tells us that swine are fond of the leaves and roots of the former, and that the smoke of it will drive away crickets and battac, or cockroaches, out of houses. The roots of the second have an astringent and bitter taste, and are used to dye dark brown. 3. The lotus, with heart-shaped toothed leaves, a plant thought peculiar to Egypt, is mentioned by Herodotus and Savary, as growing in the rivulets, and on the sides of the lakes; there are two sorts or varieties of this plant, the one with a white the other with a bluish ſlower. The calyx blows like a large tulip, and diffuses a sweet smell resembling that of the lily. The first species produces a round root like that of a potato, and the inhabitants of the banks of the lake Menzall feed upon it. 4. In the East and West Indies grows a species of this plant, named nclumbo by the inhabitants of Ceylon; the flowers, large and flesh coloured, consist of numerous petals, disposed in two or more rows; and are held sacred among the Hindoos. It is divided into several distinct cells, which form so many large round beds upon the surface of the fruit, each containing a single seed. NYMPHAEA ALBA, and LUT eA. These are aquatics, and scarcely any plant is more deserving of our attention: . The fine appearance of the foliage floating on the surface, which is interspersed with beautiful flowers, will render any piece of water very interesting: it should also be observed, that gold fish are found to thrive best when they have the advantage of the shade of these plants. It is difficult in deep water to make them take root, being liable to float on the surface, in which state they will not succeed. But if the plants are placed in some strong clay or loam, tied down in wicker baskets, and | then placed in the water, there is no fear of their success: they should be placed where the water is sufficiently deep to inundate the roots two feet, or a little more. 8 Z. 730 o A T O B L DictionARY OF MECHANICAL SCIENCE O. O, or o, the fourteenth letter, and fourth vowel, of our alpha- bet, pronounced as in the words nose, rose, &c. As a numeral, O is sometimes used for eleven ; and with a dash over it, thus, O, for eleven thousand. In music, the O, or rather a circle or double CO, is a note of time called by us a semi-breve; and by the Italians circolo. The O is also used as a mark of triple time, as being the most perfect of all figures. - OAK, in Botany, is a well-known tree, styled by way of eminence, the “lord of the forest.” In Ampthill Park, the residence of the late Lord Ossory, now that of Lord Holland, stands one of those magnificent monarchs of the wood, a particularly large oak. The circumference of its base is up- wards of forty feet; its middle girt is about thirty: it is quite hollow, forming a concavity sufficient to contain four or five middle-sized persons standing together withinside. The chief of its branches, which is much greater in dimension than many parent oaks, is supported by a couple of large wooden props, on account of its weight being too great to be kept up by the main body of the tree. There are many fine oaks in numerous other parts of the empire; as in Salecy forest, Northampton- shire, and in the Tuke of Hamilton's park in Lanarkshire. The wood of this tree is one of the most durable that grows; and its use in naval and domestic purposes is exceedingly great. The bark is used in tanning, and after this office is performed, one load of it will do more service to stiff cold land than two loads of the richest manure. For hotbeds also oak bark is in great request; but its powerfully astringent properties render it useless for medical purposes. Before oak-timber is in a state to be used, it is requisite that the trees should be barked, and suffered to stand uncut for three or four years, that they may become perfectly dry. The sawdust of this tree, and even the leaves, though much inferior to the ibark, have been found useful in tanning. The former of these is the principal vegetable production of this country, which is used in the dyeing of fustian; all the various shades of drab and brown are made with oak sawdust, differently managed and compounded. OAKUM, the substance into which old ropes are reduced when they are untwisted, loosened, and drawn asunder. It is principally used in caulking the seams, tree-nails, and bends of a ship, for stopping or preventing leaks. OAR, a long piece of timber, flat at one end; and round or square at the other, used to make a vessel advance upon the water. the blade, and that which is within the board is termed the loom, whose extremity being small enough to be grasped by the rowers, is called the handle. To push the boat or vessel forwards by means of this instrument, the rowers turn their backs forwards, and dipping the blade of the oar in the water, pull the handle forward, so that the blade at the same time may move aft in the water. But since the blade cannot be so moved without striking the water, this impulsion is the same as if the water were to strike the blade from the stern towards the head: the vessel is therefore necessarily moved according to the direction. Hence it follows, that she will advance with the greater rapidity, by as much as the oar strikes the water more forcibly ; consequently an oar acts upon the side of a boat or vessel like a lever of the second class, whose fulcrum is the station upon which the oar rests on the boat's gunwale. In large vessels this station is usually called the row port, but in lighters and boats it is always termed the row-lock, Oars for ships are generally cut out of fir timber; those for barges are made out of New England or Dantzic rafters; and those for boats, either out of English ash, or fir rafters from Norway. To Boat the OARS, is to cease rowing, and lay the oars in the boat. Get your OARs to pass, the order to prepare them for rowing. To Ship the OARS, is to place them in the row-locks, as To Unship them, is to take them out of the row locks, and is frequently practised in passing very near a vessel, to prevent breaking the oars, &c. The flat part which is dipped into the water is called OATH, an affirmation or promise, accompanied with an invocation of God to witness what we say, and with an impre- cation of his vengeance, or a renunciation of his favour, if what we affirm be false, or what we promise be not performed. Hence oaths are either assertory or promissory. Quakers and Moravians, interpreting the scriptures according to their own | judgments, refuse to swear before any magistrate, or in any court; and our justices and judges, with a degree of liberality which many condemn, allow the Quaker and Moravian to affirm upon their bare word what another religionist would be required to swear to. • OATS, are the seeds or grain of an annual plant, too well known, and too much cultivated throughout every part of Europe, to need any description. The country from whence they were originally imported is not known. The principal use of oats in this country is for the feeding of horses. In the northern parts of England, and in Scotland, they are applied also to the nutriment of man. When simply freed from their husks, they are called groats or grits ; in this state they are much used in broths, and other kinds of nutriment for the sick and infirm. More frequently, however, they are ground into oatmeal, which is made into cakes, biscuits, &c. The husks infused in water, and allowed to remain till the water becomes somewhat acid, are boiled to a jelly called sowins. A grateful and nutritive kind of jelly, which has the name of flummery, is also made of oatmeal, boiled with water, and flavoured with a little orange-flower water, and sugar. Oats will thrive in almost any soil, but are chiefly productive on land newly broken up. They are usually sown in February, and the harvest com- mences about August. Several kinds or varieties are culti- wated in different parts of England, such as white oats, black oats, brown or red oats, Tartarian or reed oats, Friesland oats, Poland oats, and some others; but of these the first are con- sidered the most valuable. OAT Grass, the name of a coarse grass that in some particu- lar soils may be cultivated to some advantage. OAT, Wild, a species of grain, considered by agriculturists as a weed, which cannot, without much difficulty, be eradicated from a soil of which it has once taken possession. The seed will retain its germinating power for many years in the ground, and spring forth when preparations are made for other crops. Cutting in an unripe state seems to be the only way to ensure its extirpation. OBEAH, a species of witchcraft practised among the ne- groes, the apprehensions of which operating upon their super- stitious fears, is frequently attended with disease and death. OBELIAS, small cakes used among the ancients, which, toasted on small Spits, and dipped in wine, were eaten as desserts. - * OBELISCUS MARMOREUS. In Natural History, this name is given to a remarkable species of shell fish, but never found alive in modern times. In a fossil state it is frequently Seen in Swedish stone, used for pavements, and some other purposes. - O BELISK, in Architecture, a truncated, quadrangular, and slender pyramid, raised as an ornament, and frequently enriched with inscriptions in bas-relief, or hieroglyphics. OBITUARY, a funeral register, in which are written the names of the dead. OBJECT GLAss, in Optical Instruments, is that which is placed towards the object, the other extreme lens being called the eye-glass, being that to which the eye is directed. OBJECTIVE LINE, in Perspective, is any line drawn on the geometrical plane, the representation of which is sought in the draught or picture. OBLATA, things offered voluntarily to kings by their subjects. , OBLATE, Flattened, or Shortened, having its axis shorter than its middle diameter, being formed by the rotation of an ellipse about the shorter axis. The earth is an oblate sphe- roid, the polar diameter being shorter than the equatorial ae ： ----^^^º. Zº//^^^^^^| º Y%|×|×//|×^~|×^^^ ^^^^^^|×°′^^^ O B S DICTIONARY OF ME CHANICAL SCIENCE. O B S 73'ſ diameter, in the proportion of 331 to 332: that is to say, the polar diameter is 7900 miles, and the equatorial diameter 7924 miles **º- ôňati, secular persons who bestowed themselvés and estates on some monastery, for which they were admitted as lay brothers. . . . . sº OBLATIONS ; these primarily denoted things offered to God either through the church, or the priests. now used in a less restricted sense. $ OBLIGATION, a bond containing a penalty, with a con- dition annexed, either for payment of money, performance of covenant, or the like. *. . ... • * > OBLIGER, in Law, he who enters into an bbli obligee the person to whom it is entered into. OBLIQUE, in Geometry, something slant, or inclining from the perpendicular, as oblique ascension, oblique circle, oblique descension, oblique planes, in Dialing; oblique sailing, in Navigation. See these several words. OBLONG, in Geometry, a figure that is longer one way than another, as one of the columns of this page of paper; which takes the form of a parallelogram. . . . OBOLARIA, a genus of plants belonging to the didynamia class, and ranking under the 40th order, Personatae. * OBQLUS, in Antiquity, an ancient Athenian coin, worth a penny farthing. In medicine, obolus signifies a weight of ten." grains, or half a scruple. a weight of one pound. . º, OBRINE, knights of a military order, instituted in the 13th century by Conrade. *. OBSERVATION, in Astronomy and Navigation, denotes' the measuring with some proper instrument for the purpose, the angular distance, altitude, &c. of the sun, moon, or other celestial body. OBSERVATORY, OBservator IUM, a place destined for observing the heavenly bodies; or a building usually in form of a tower, raised 'on some eminence, and covered with a terrace for making astronomical observations. The more celebrated observatories are, 1. The Greenwich Observatory, or Royal Observatory of England, was built in 1676, by order of Chas. II. at the solicitation of Sir Jonas Moore and Sir C. Wren, and furnished with the most accurate instruments by the same, particularly a noble sextant of seven feet radius, with tele- scopic sights. to Flamstead, a man who seemed born for the employment. For fourteen years, with unwearied pains, he watched the motions of the planets, and particularly those of the moon, as was given him in charge; that a new theory of that planet being found, exhibiting all her irregularities, the longitude might thence be determined. In the year 1690, having pro- vided himself with a mural arch of seven fect diameter, well fixed in the plane of the meridian, he verified his catalogue of the fixed stars, (which hitherto had depended altogether on the distances measured with the sextant,) after a new and very different manner, viz. by taking the meridian altitudes, and the movements of culmination, or the right ascension and declina- tion. With this instrument he was so pleased, that he laid the use of the sextant almost wholly aside; and in this way was the astronomer royal employed for thirty years; in the course of which time nothing had appeared in public worthy so much expense and preparation; so that the observer seemed rather to have been employed for his own sake, and that of a few friends, than for the public; though it was notorious the observations that had been made were very numerous, and the papers swelled to a great bulk. This occasioned Prince George of Denmark, in 1704, to appoint certain members of the Royal Society, viz. the Hon. Fr. Robarts, Sir C. Wren, Sir Isaac Newton, Dr. Gregory, and Dr. Arbuthnot, to inspect Flam- stead's papers, and select such as they should think fit for the press, purposing to print them at his own expense; but the prince dying before the impression was half finished, it lay still for some time; till at length it was resumed by order of Queen Anne, and the care of the press committed to Dr. Arbuthnot; and that of correcting and supplying the copy to Dr. Halley. Such was the rise and progress of the “Historia Coelestis ;” the principal part whereof is the catalogue of fixed stars, called also the Greenwich Gatalogue. Flamstead was * gation; as, * The term is Among the Sicilians, obolus denotes The province of observing was first committed : succeeded by Dr. Halley; and Dr. Halley, in 1742, by Dr. Bradley, so deservedly celebrated for his discovery of the aberration of the stars, and the mutation of the earth's axis, after Dr. Bradley, the appointment was, in 1762, conferred upon Mr. Bliss, who was succeeded in 1785 by Dr. Maskelyne, the late worthy astronomer royal ; upon whose demise, in 1811. this important office was conferred upon Mr. Pond. The Greenwich observatory is found, by very accurate observation, to lie in 510 28' 307 north latitude. 2. The French Observatory, built by Louis XIV. in the . Fauxbourg St. Jaques, Paris, is a very singular, but withal, a ... very magnificent building. It is eighty feet high, and at the top there is a terrace. It is here M. de Lahire, M. Cassini, &c. have been employed. This observatory was begun in 1664, and finished in 1672. The difference in longitude be- tween this and Greenwich Observatory is 2°20' 15" each. In the Paris Observatory is a cave, or cellar, of one hundred and seventy feet descent, for making various experiments, particu- } larly such as relate to congelations, refrigerations, indurations, , conservations, &c. And in this cave there is a thermometer of M. de Lahire, which is always at the same height, indicating the temperature of the place to be always the same. 3. Tycho Brahe's Observatory in the little island Ween, or the Scarlet Island, between the coasts of Schonen and Zea- land in the Baltic, was erected, and furnished with instruments, at his own expense; and was called by him Uraniburgh. In this place he spent twenty years in observing the stars. S We may enumerate here some other observatories, as that of Pekin, erected by a late emperor of China in his capital, upon the recommendation of the Jesuit missionaries; and that of the Bramins at Benares, in the East Indies, of which we give an engraving, (see plate Observatory) representing and illustrat- ing several particulars, as in the following description :- The observatory at Benares, built by order of the emperor Ackbar, was once a magnificent structure; the lower part of it is now, however, converted into stables; the court yards and apartments are still spacious. It stands on the banks of the Ganges, and the summit is approached by a staircase leading to a large terrace, where numerous instruments still remain in great preservation, stupendously large, immoveable from the spot, and built of stone, some of them being upwards of twenty feet in height. Their graduation is very exact. º The situation of the two large quadrants, marked A in the plate, whose radius is nine feet two inches, by their being at right angles with a gnomon at 25° elevation, shew the stability and excellence of the architecture. The three sights on this gnomon occupy a space of 383 feet, and they are perfectly true. The quadrants, 20 feet in diameter, are built in perpen- dicular ovals, that follow the meridian of the place. The arcs of those quadrants are graduated into nine parts, and each of these again into ten parts = 90° in all. Figure A is properly an equinoctial sun-dial, that expresses solar time by the shadow of a gnomon upon two quadrants, one east and the other west of it. Fig. B is an instrument for determining the exact hour of the day by the shadow of a gnomon, which stands perpendicular to, and is in the centre of, a flat circular stone, supported in an oblique position by four upright stones and a cross piece, so that the shadow of the gnomon, which is a perpendicular iron rod, is thrown upon the division of the circle described on the face of the flat circu- lar stone. Figure C is a brass circle, about two feet diameter, moving vertically upon two pivots between two stone pillars, having an index or hand turning round horizontally on the centre of this circle, which is divided into 360 parts. This is in fact an azimuth instrument; since its use is to measure on what point of the horizon any celestial body may rise or set. Figure D consists of two circular walls, the outer one forty feet diameter and eight feet high, and the inner wall, half that height, appears to be a parapet, from which to observe the divisions on the upper circle of the outer wall. Both circles are divided into 360 equal parts, each divided into 20 lesser divisions. In this inner circle is a pillar exactly in its centre, in which a perpendicular rod has been once placed. tº ſº Figure E is a small equinoctial sun-dial, constructed simi. larly to fig. A. | 782 O B S : DICTIONARY OF MECHANICAL SCIENCE. oc c The principal instruments for a fixed observatory are, a large fixed quadrant or a circular divided instrument, chiefly for measuring vertical angles; a transit instrument; an equato- rial instrument; a chronometer, or regulator; one or more powerful telescopes; a fixed zenith telescope, and a night telescope. The quadrant or quarter of a circle, divided into 90 degrees, and each degree subdivided into minutes or smaller parts, has been made of various sizes; some of them having a radius even of eight or mine or more feet in length. . When those quadrants do not exceed one or two, or at most three, feet, in radius, they are generally fixed upon their particular stands, which are furnished with various mechanical contrivances, that are necessary to place the plane of the qua- drant perpendicular to the horizon, and for all the other neces- sary adjustment. But large quadrants are fixed upon a strong wall. See QUADRANT. - The transit instrument consists of a telescope of any conve nient length, fixed at right angles to a horizontal axis, which axis is supported at its two extremities; and the instrument is generally situated so that the line of collimation of the teles- cope may move in the plane of the meridian. The use of this instrument is to observe the precise time of the celestial bodies’ passage across the meridian of the observatory. See TRANSiT INSTRUMENT. - To adjust the Clock by the Sun's transit over the Meridian. Note the times by the clock when the preceding and following edges of the sun’s limb touch the cross wires. The difference between the middle time and 12 hours shews how much the mean or time by the clock is faster or slower than the apparent or solar time for that day: to which the equation of time being applied, will shew the time of mean noon for that day, by which the clock may be adjusted. Astronomical or equatorial sector, an instrument for finding the difference in right ascension and declination between two objects, the distance of which is too great to be observed by the micrometer, was invented by Graham. See EQUAtoRIAL. Equatorial or Portable Observatory, an instrument designed to answer a number of useful purposes in practical astronomy, independently of any particular observatory; it may be made use of in any steady room, and performs most of the useful prob- lems in the science. The principal uses of this equatorial are: 1. To find the meridian of one observation only : for this purpose elevate the équatorial circle to the co-latitude of the place, and set the declination semi-circle to the sun's declina- tion for the day and hour of the day required; then move the azimuth and hour circles both at the same-time, either in the same or contrary directions, till you bring the centre of the cross hair in the telescope exactly to cover the centre of the sun; when that is done, the index of the hour circle will give the apparent or solar time at the instant of observation ; and thus the time is gained, though the sun is at a distance from the meridian ; then turn the hour circle till the index points precisely at 12 o'clock, and lower the telescope to the horizon, in order to observe some point there in the centre of your glass, and that point is your meridian mark found by one observation only ; the best time for this observation is three hours before - or three hours after twelve at noon. 2. To point the telescope on a star though not on the meri- dian, in full day-light. Having elevated the the equatorial cir- cle to the co-latitude of the place, and set the declination semi- circle to the star's declination, move the index of the hour cir- cle till it shall point to the precise time at which the star is then distant from the meridian, found in tables of the right ascension of the stars, and the star will then appear in the glass. ...Besides these uses peculiar to this instrument, it is also ap- plicable to all the purposes to which the principal astronomical instruments, viz. a transit, a quadrant, and an equal altitude instrument, are applied. ' Of all the different sorts of chronometers or time-keepers, a pendulum clock, when properly constructed, is undoubtedly capable of the greatest accuracy; therefore, such machines are most recommendable for an observatory. The situation of this clock must be near the quadrant, and near the transit instru- ment; so that the observer, whilst looking through the telescope of any of those instruments, may hear the beats of the clock, and count the seconds. A pretty good telescope placed truly vertical in an observa- tory, is likewise a very useful instrument, as the aberration of the stars, and latitude of the place, may be observed and, deter- mined by the use of such an instrument, with great ease and accuracy. See Telescope. , • . The night telescope is a short telescope, which magnifies very little; but it collects a considerable quantity of light, and has a very great field of view ; it therefore renders visible several dim objects, which cannot be discovered with telescopes of considerably greater magnifying powers; and hence it is very useful for finding out nebulae, or small comets, or to see the arrangement of a great number of stars in one view. - The principal instruments that are at present used for marine astronomy, or for the purposes of navigation, are, that incom- parably useful instrument called Hadley’s sextant or quadrant, or octant; a portable chronometer; and a good telescope. , OBSIDLAN, a volcanic glass, resembles lumps of black glass. Its surface is smooth, it is hard, and strikes fire with steel. It is common in the neighbourhood of volcanoes, and in some basalts, probably the products of volcanic fires now extinguish- ed. In Lipari, one of the volcanic isles, the mountain de la Castagna, according to Spalanzani, is wholly composed of vol- canic glass, which appears to have ſlowed in successive currents like streams of water falling with a rapid descent, and suddenly frozen. This glass is sometimes compact, and sometimes. po- rous and spungy. Obsidian appears to be lava suddenly cooled; if a mass of lava or basalt be exposed to the heat of a glass furnace, it melts into a shining black or greenish black glass. Numerous veins of obsidian are said to intersect the cone of Mount Vesuvius, and serve as a cement to keep together the loose materials of which it is composed. Obsidian is some- times ground and polished, and used for mirrors. - OBSIDIANUS LAPIS, in the natural history of the an- cients, was the name of a stone sometimes called China marble. It is black, smooth, hard, difficult to cut, capable of receiving a fine polish, and was used among the Greeks for the making of reflecting mirrors. In Peru, at the time of its conquest by the Spaniards, the inhabitants used it for mirrors, and in Europe it has been converted into reflectors for tele- Scopes. * - OBSTRUCTION, in Medicine, such an obturation of the vessels as prevents the circulation of the fluids, whether of the food and vital, or of the morbid and peccant kind, through them. OBTUSE, literally implies any thing blunt or dull, in con- tradistinction to acute, sharp, or pointed. - OBTUse Angle, Angular Section, Cone, Hyberbola, &c. - OCCATION. In ancient husbandry this term was nearly synonymous with our modern harrowing, though the instru- ment employed was a kind of rake. - & OCCIDENT, in Astronomy and Geography, is the same as westward, or point of the horizon where the sun sets. A planet is said to be occident when it sets after the sun. OCCIDENT, Equinoctial, that point of the horizon where the sun sets when he crosses the equinoctial, or enters the sign Aries or Libra. OcCIDENT, Estival, that point of the horizon where the sun sets at his entrance into the sign Cancer. - OCC1D ENT Horizon. See Horizon. --- OCCIDENT, Hybernal, that point where the sun sets when he enters the sign Capricorn. OCCULT LINE, in Geometry, a dry or obscure line, which is drawn as a necessary part of the construction of a figure or problem, but which is not intended to appear after the plan is finished. • OCCULT, something hidden or secret; as the occult qualities of bodies. - OCCULTATION, the obscuration of a planet or star by the interposition of the moon, or other planet, between it and our eye. - OCCUPANCY, in Law, the taking possession of things which before belonged to nobody. This is the foundation of property. Hence, OCCUPANT, in Law, is the person who first seizes, or gets possession of a thing. And, OCCUPATION, in Law, is use or tenure, trade or mystery. | OCEAN, the Sea, that mighty element, which occupies more O C E O C. E. 733 DICTIONARY OF MECHANICAL scIENCE, than two-thirds of the terraqueous globe. In the Northern hemisphere, the land bears to the water the proportion of 419 to 1000; or nearly one half; but in the Southern hemisphere only of 129 to 1000; so that the whole mass of land is to that of sea, as 274 to 1000. And almost the whole of this vast body of wateris collected in one immense basin called the Southern ocean. Division of the waters into Oceans, Seas, Lakes, Straits, Gulfs, Bays or Creeks, Rivers, &c.—The waters are divided nto three extensive oceans, (besides lesser seas, which are only branches of these,) viz. the Atlantic, the Pacific, and the Indian ocean. The Atlantic, or Western ocean, 3000 miles wide, divides the eastern and western continents. The Pacific, 10,000 miles over, divides America from Asia. The Indian ocean lies between the East Indies and Africa, being 3000 miles wide. The geographical definition of the ocean is a great and spacious collection of water, without any entire separation of its parts by land; as the Atlantic ocean. The sea is a smaller collection of water, which communicates with the ocean, confined by the land; as the Mediterranean and the Red sea. A lake is a large collection of water, entirely surrounded by land; as the lake of Geneva, and the lakes in Canada. A strait is a narrow part of the sea, restrained or lying between two shores, and opening a passage out of one sea into another; as the strait of Gibraltar, or that of Magellan. This is some- times called a sound; as the strait into the Baltic. A gulf is a part of the sea running up into the land, and surrounded by it, except at the passage whereby it is communicated with the sea or ocean. If a gulf be very large, it is called an inland sea; as the Mediterranean: if it do not go far into the land, it is called a bay, as the Bay of Biscay: if it be very small, a creek, haven, station, or road for ships, as Milford Haven. Rivers, canals, brooks, &c. need no description: for these lesser divisions of water, like those of land, are to be met with in most countries, and every one has a clear idea of what is meant by them. But in order to strengthen the remembrance of the great parts of the land and water we have described, it may be proper to observe, that there is a strong analogy or resemblance between them. ** - On the Saltness of the Sea.—Sea water is salt, while that of rivers is mild, fresh, sweet, and fit for human purposes. Some think that this saltness arises from great beds of salt lying at the bottom of the sea. But others more rationally suppose it is owing to the following cause. Salt is one of the original principles of nature, and is mixed, in greater or less quantities, with most other bodies. Now all rivers run into the sea, and carry some salt with them ; but no rivers run out of it, nor is any water taken from it, except by exhalation or evaporation. But chemists have demonstrably proved, that no salt ean ascend in either of these ways; and consequently, all the salt carried into the sea by the immense numbers of rivers that run into it, remains behind, and occasions its saltness. That no Salt ascends from the sea, either by exhalation or evaporation, is evident from this, that rain-water, which falis from the clouds, and which was originally exhaled from the sea, is, of all kinds of water, the sweetest, purest, and lightest, and is made the standard by which philosophers judge of all other waters. The water of the ocean contains about the 30th part of its weight of salt; the water of the Baltic, holds only from the 200dth to the 100dth part, consequently the water of the Baltic ought to stand I-40th part higher from the bottom of the Sea, than the water of the ocean, in order to maintain its hydrostatic equilibrium. It is observed on the Baltic shores, that the water subsides, and that its surface is lower in all parts than it formerly was. May not this be in consequence of the Baltic becoming salter, and thus approximating to the specific gravity and height of the oeean? "See Tides. The Currents of the oeean come next to be considered. Cur- rents are certain progressive movements of the sea, by which all bodies floating therein are compelled to alter their course or Welocity, or both, and submit to the laws imposed upon them by the current. The setting of a current is that point of the compass towards which the waters run, and the drift of the current is the rate it runs at in an hour. Currents in the sea are either natural or general, as arising from the diurnal revolu- tion of the earth on its axis; or accidental, and particularly caused by the waters being driven against promontories, or into gulfs and straits, where, wanting room to spread, they are driven back, and thus disturb the ordinary flux of the sea. The following observations are made by Varenius:-" Cur- rents are various, and directed towards differents parts of the ocean, of which some are constant and others periodical. The most extraordinary current of the sea, is that by which part of the Atlantic or African ocean moves about by Guinea, from Cape Verd, towards the curvature or bay of Africa, which they call Fernando Po, viz. from west to east, contrary to the general motion. And such is the force of this current, that when ships approach too near the shore, it carries them vio- lently towards the bay, and deceives the mariners in their reckoning. There is a great variety of shifting currents, which do not last, but return at certain, periods; and these do, most of them, depend upon and follow the anniversary winds or monsoons, which by blowing in one place may cause a cur- rent in another. At Java, in the straits of Sunda, when the monsoons blow from the west, viz. in the month of May, the currents set to the eastward, contrary to the general mo. tion. Also between the island of Celebes and Madura, when the western monsoons set in, viz. in December, January, and February, where the winds blow from the north-west, or be- tween the north and west, the currents set to the south-east, or between the south and east. At Ceylon, from the middle of March to October, the currents set to the southward, and in the other parts of the year to the northward: because at this time the southern monsoons blow, and at the other the northern. Between Cochin-china and Malacca, when the western monsoons blow, viz. from April to August, the cur- rents set eastward against the general motion, but the rest of the year set westward; the monsoon conspiring with the general motion. They run so strongly in those seas, that in- experienced sailors mistake them for waves that beat upon the rocks, known by the name of breakers. So for some months after the 15th of February, the currents set from the Maldives towards India on the east, against the general motion of the sea. On the shore of China and Cambodia, in the months of October, November, and December, the currents set to the north-west, and from January to the south-west, when they run with such a rapidity of motion about the shoals of Parcel, as to seem swifter than an arrow. At Pulo Condore, upon the coast of Cambodia, though the monsoons are shifting, yet the currents set strongly towards the east, even when they blow to a contrary point. Along the coasts of the bay of Bengal as far as the Cape Romania, at the extreme point of Malacca, the current runs southward in November and December. When the moonsoons blow from China to Malacca, the sea runs swiftly from Pulo Cambi to Pulo Condore, on the coast of Cambodia. In the bay of Sans Bras, not far from the Cape of Good Hope, there is a current particularly remarkable, where the sea runs from east to west to the landward; and this more vehemently, as it becomes opposed by the winds from a con- trary direction. The cause is undoubtedly owing to some adjacent shore, which is higher than this.” These currents constantly follow the winds, and set to the same point with the monsoon or trade-wind at sea. Under the equator, where the motion of the earth is the greatest, the currents are so violent, that they carry vessels very speedily from Africa to America; but absolutely prevent their return the same way; so that the ships are forced to run as far as the fortieth degree of latitude, to find a passage into Europe. The currents in the straits of Gibraltar almost constantly drive to the eastward, and carry ships into the Mediterranean: they are also usually found to drive the same way in St. George's Channel. The great violence and danger of the sea in the straits of Magellan, is attributed to two contrary currents set- ting in, one from the south and the other from the north sea. Currents, as they relate to navigation, may be defined as certain progressive motions of the water of the sea in several plaees; by which a ship may happen to be carried forward more swiftly, or retarded in her course, according to the direc- tion or setting of the current in with or against the course or way of the ship. The setting or progressive motion of the cur- rent, may be either quite down to the bottom, or to a certain determinate depth. . As the knowledge of the direction and velocity of currents is a very material article in navigation, it 9 A 734 O C. H. O C. T. DICTIONARY OF MECHANICAL SCIENCE. is highly necessary to discover both, in order to ascertain...the ship's situation and course with as much accuracy as possible. This, some do by the ripplings of the water, and by the driving of the froth along the shore, when in sight of it; but the most successful method which has been hitherto attempted by mariners, is the following:—A common iron pot, which may contain four or five gallons, is suspended by a small rope, fastened to its ears or handles, so as to hang directly upright, as when placed upon the fire. This rope, which may be from 70 to 100 fathoms in length, being prepared for the experiment, is coiled in the boat, which is hoisted out of the ship at a pro- per opportunity, when there is little or no wind to ruffle the surface of the sea. The pot being then thrown overboard into the water and immediately sinking, the line is slackened till about 70 or 80 fathoms run out, after which the line is fastened to the boat's stern, by which she is accordingly restrained, and rides as at anchor. The velocity of the current is then easily tried by the log and half-minute glass, the usual method of dis- covering the rate of a ship's sailing at sea. (See CALM.) The course of the stream is next obtained by means of the com- pass provided for this operation. This shews whether there be any current or no; and if any, which way it sets, and at what rate it drives: observing, however, to add something to the drift, for the boat's drift, for though she appear to stand still, yet, in reality, she is found to move. This addition expe- rience has thus determined; if the line she rides by be 60 fathom, a third part of the drift is to be added, if 80 fathom a fourth, if 100 fathom a fifth. - If a ship sail along the direction of the current, it is evident the velocity of the current must be added to that of the vessel : if her course be directly against the current, it must be sub- tracted: if she sail athwart the current, her motion will be compounded with that of the current; and her velocity aug- mented or retarded according to the angle of her direction with that of the direction of the current: i.e. she will proceed in the diagonal of the two lines of direction, and will describe or pass through that diagonal in the same time wherein she would have described either of the sides by the separate forces. Hence it is plain, 1. If the velocity of the current be less than that of the ship, then the ship will advance so much as is the difference of these velocities. 2. If the velocity of the current be more than that of the ship, then will the ship fall as much astern as is the difference of these velocities. 3. If the velocity of the current be more than that of the ship, then will the ship remain stationary, the one velocity destroying the other. If the current thwarts the course of a ship, it not only diminishes or increases her velocity, but gives her a new direc- tion, compounded of the course she steers, and the setting of the current. Under-currents, are distinct from the upper or apparent, and in different places set or drive a contrary way. Dr. T. Smith makes it highly probable, that in the Downs, in the straits of Gibraltar, &c. there is an under-current, whereby as much water is carried out as is brought in by the upper cur- rent. This was confirmed by an experiment made in the Baltic sound, by the seamen on board one of the king's frigates: they went with the pinnace into the midstream, and were carried violently by the current. Soon after that, they sunk a basket with a large cannon bullet, to a certain depth of water, which gave check to the boat's motion; and sinking it still lower and lower, the boat was driven ahead to the windward, against the upper current, the current aloft not being above four or five fathom deep, and the lower the basket was let down, the stronger the under-current was found. Dr. Halley solves the currents setting in at the straits without overflowing the banks, by the great evaporation, without supposing any under-current. OCELOT, in Zöology, the Mexican cat, the Felis Pardalis of Linnaeus. OCHNA, a genus of plants belonging to the polyandria class, and in the natural order ranking with those whose order is doubtful. - OCHRA, in Ornithology, the name of a species of moor-hen. OCHRA, a vegetable substance found in the West Indies, where it is used to thicken soup, as well as for other purposes. OCHRE, (Red) Reddle, or Red Chalk, is an iron ore of blood-red colour, which is sometimes found in powder, and sometimes in a hardened state. It has an earthy texture, and stains the fingers when handled. The principal use of red chalk is for drawing; the coarser kinds are employed by car- penters and other mechanics, and the finer kinds by painters. for the latter purpose it should be free from grit, and not too hard. In order to free it from imperfections, and render it better for use, it is sometimes pounded, washed, mixed with gun, and cast into moulds of convenient shape and size. lunder the name of reddle this substance is much used for the marking of sheep; and, when mixed with oil, for the painting of pales, gates, and the wood work of outbuildings. - ÖCHROMA, a genus of plants belonging to the monadel- phia class, and ranking in the natural method under the 35th class, columniferae. - . - OCTAGON, in Geometry, is a figure of eight sides and angles, which, when the sides and angles are all equal, is called a regular octagon, and when they are not both equal, an irregular octagon. The angle at the centre of an octagon is 45 degrees, and the angle of its sides 135 degrees. The area of a regular octagon whose side is 1 = 2 (1 + V 2) = 4.8284271; and therefore when the side is s, the area = 48284271 sº, and the radius of its circumscribing circle = S - - On a given Line A B to construct a regular Octagon.—On the extremities of the given line A B, erect the indefinite perpendiculars A F, B E, and produce A B both ways to m and n. Bisect the angles m A F, n B E, by the lines A H and B C, and take A H and B C both equal to A B. Draw G H and DC parallel to AF or BE, and each equal to A B ; then from G and D as centres, with radius A B, describe arcs cutting the perpendiculars in F and E. Join F G, F E, and ED, so is A B C D EFG H, the octagon required. - - - - OCTANDRIA, the eighth class of Linnaeus's sexual system, consisting of plants having eight stamina. * OCTANS HADLIENUS, Hadley’s Quadrant, is the Polar constellation in the southern hemisphere; it contains forty- three stars, of which one is of the third magnitude, and all the rest are under the fourth. The splendid nebula near the South Pole, and called by sailors the Magellanic cloud, appears to the naked eye like a part of the Milky Way, but through a telescope like a mixture of clouds and stars. e OCTANT, the eighth part of a circle. Oct ANT, or Octile, is also an ancient term in astronomy, to denote one of the aspects, viz. when two planets are distant from each other 45°. OCTAVE, in Music, an harmonical interval, consisting of seven degrees or lesser intervals. - OCTAVE. See CHORD. OCTOBER, being the eighth month of the ancient Roman calendar, but the tenth according to the Julian year. This month contains 31 days, on or about the 22d of which the sun enters the sign Scorpio. - The Kalendar. of Animated Nature around London, presents in this month, the red-wing, at the same time that snakes and vipers bury themselves. Hooded-crows and wood-pigeons arise, hen-chaffinches congregate and prepare to remove to another climate, leaving their males here. The snipe appears in the meadow ditches, wild geese quit the fens for the rye lands, rooks visit their nest trees, some larks sing, the wood- cock returns, and spiders' webs abound. In Vegetable Nature, we find the arbutus, the holly, the China holly-hock, and the China aster in bloom. The leaves of many trees are now quite yellow, and others fall off pro- fusely. Various annual plants are in flower. . In the Kitchen Garden, culinary vegetables, as the small salads, lettuces, radishes, are sown, as are Mazagan beans, and hotspur or frame pease. T9;ave seed, cabbages, savoys, beet, parsnips, carrots, turnips; bulbing and Welsh onions, are transplanted; newly raised annuals must be protected, culinary perennials propagated; endivc and lettuce trans- planted to warm borders. The routine culture of earthing, ſº Xs={ 7. T O D O O D O DICTIONARY OF MECHANICAL scIENCE., 735 hoeing, weeding, digging and trenching must not be neglected. Take up potatoes, beet, Jerusalem artichokes, parsnips, salsafy, scorzonera, skirret, and horse-radish of two years’ growth, and preserve them in dry sand from the sea-shore. Gravel-pit sand is not by any means good for this purpose, as it very fre- quently holds the drift of vegetable substances, or earth. . In the Hardy Fruit Department, all sorts of hardy fruit trees are to be planted as soon as the leaves have dropped off; fig- trees are to be protected; late grapes shielded from frost by matting; except the raspberry, elder, and fig, all sorts of fruit trees are to be pruned; ground for new plantations is to be prepared; grapes, apples, and other fruits, must now be gathered; and long keepers are to be barrelled and stored in the fruit-room, or cellar. ! - In the Culinary Hot-house Department, in the glass-case with- out artificial heat, plant lettuces and cauliflowers under frames to stand the winter, sow small salads, slacken the heat in hot- beds and pits. . In the pinery, shift and renew the bark-bed : prune in the forcing-house, cleanse and repair flues, mend broken glass, and paint when necessary. & In the Flower Garden open Department, sow annuals in pots for prolongation, in cold frames and pits; and some of the hardier sorts in warm borders, for the following early spring ; as larkspur, adonis, belvedere, pansy, persicaria, annual stock. Propagate by dividing the root, as of daisies and of other edging plants. Plant border bulbs; transplant biennials and perennials, in the flower nursery, to stand till the spring. Trotect auriculas, carnations, and other flowers, from heavy rains. Remove dahlia roots to dry in the open shed, prepara- tory to carrying them into the store-room. In the routine cul- ture, prepare composts, stir the ground only in dry weather. In the Flower Garden Hot-house Department, begin about the middle of the month to fill frames and pits with pots of migno- nette, stocks, &c. for prolongation during the winter season; roses and hyacinths may now be put in bottom heat, and water-glasses brought into use. All plants must be replaced in the green-house, which should have air night and day when the temperature keeps up to 35°. Fires must be applied to the dry stove to keep the temperature at 47°; but in the bark or moist stove, the medium heat should be 70°. In the Pleasure Ground and Shrubbery, plant hardy trees, prune evergreens, clear away all rubbish, roll, mow, sweep, hoe, weed. And in the Nursery Department, sow for stocks. The plum, cherry, almond, medlar, apple, pear, quince, bar- berry, service-tree, walnut, filbert, and hazel, may be sown. Cuttings of elder planted, fruit trees removed, as this is the best month for transplanting them. Permanent plantations and park scenery may now be planted, except in bleak situ- ations, when the spring does best. Thin, prune, and fell generally; and let all drainings be worked now. In short, operations on grounds should now be executed vigorously, in all weathers; as it is better to keep the men on, than, with the view of saving a few pounds, lose a portion even of indifferent weather in October. ODE, a song or a composition proper to be sung. ODD NUMBER, that which cannot be divided into two equal integral parts, or which, when divided by 2, leaves a remainder 1. ODDLY ODD NUMBER, that when divided by 4 leaves 3 for a remainder, or that which is of the form 4 m + 3. ODOMETER, is an instrument for measuring the distance travelled over by a post chaise or other carriage; it is attached to the wheel, and shews, by means of an index and dial-plate, the distance gone over. ODOURS, those invisible particles which disengage them- selves from different bodies by the action of some gas, or by friction, mixture, and fermentation; and also by the exhalent vessels of animals and vegetables. They are also called efflu- wha, a learned term to conceal ignorance; for nobody can tell what these effluvia are. It is probable that these particles, if such there be, are kept in the state of gas, or vapour, by the presence of heat. All bodies, for any thing we know, may give out these particles, though we can perceive only such of them as affect our sense of smell. " ' ". . . . What renders this probable, is, that many substances which are thought to be without smell in one circumstance, smell strongly in others. Flint and quartz, for instance, give out a strong smell on being rubbed or struck: clay smells on being wetted; arsenic, on being heated, smells like garlic; and golā and other inodorous metals, in some circumstances, small strongly. The particles must be very minute, however much they may affect the organ, at least if we may judge of this by their weight. This can be shewn by an experiment; but it takes some time to perform it. - . º Experiment on Odours. Take a grain of musk, very accu- rately weighed in the most delicate balance. Put it in such a place as it may be kept from moisture or dust, while it has free access to the air. Allow it to remain here for one, two, three, or twelve months. During all this time it will not cease to diffuse a strong odour all around it. Weigh it again very nicely at the end of the period you have allotted for the experiment, and you will find that it has not lost the least perceptible weight, though it has been for so long giving out daily and hourſy a strong odour. Yet if we believe Le Cat, who has given us no reason for his opinion, but puts us off with a simile-odours are much heavier than air, and rise in it only in consequence of the Velocity with which they are ejected from bodies, as a horse at full speed, and the wind together, raise a cloud of heavy dust; although however, the foregoing experiment has been repeat- edly urged as conclusive, we are disposed to doubt the legiti- macy of the inference. For why may not odours be similar in their nature to heat, to light, to the magnetic, to the galvanic, or to the electric principles 2 - Odours cannot be perceived by any of the senses but smell- ing. We cannot see them, hear them, nor touch them, and we think it is somewhat doubtful whether we can taste them. Do they not then bear a close analogy to light and heat in this re- Spect; though they be not susceptible of reflection and refrac- tion as light and heat are, because odours are not propagated in straight lines : They differ from sound in being capable of transmission through a vacuum made by an air pump, a pro- perty which might be advantageously made use of for investi- gating their properties more accurately than has yet been done. - During the rage for discovering chemical elements, which prevailed some years ago, it was maintained that aroma was an element of this sort, on the same vague fancy that colouring matter and extractive, and miasma, were set down as such ; and the opinion still lingers among those who trust to the authority of names and of books, rather than be at the trouble of thought or inquiry for themselves. Fourcroy proved the opinion false as it regarded aroma; and we believe it is equally so in other CaSeS. How Smell is produced.—However this may be, it is clear enough, that the odoriferous principles, particles, or gases, are drawn up into the nostril in breathing; and by mixing or combining with the fluid which covers the nerves, produce in these nerves the sensation of smell. The moistness of the membrane in indispensable to the sensation of smell, for when the membrane becomes dry, no smell is perceived. The mois- ture may act, perhaps, as a solvent for the odoriferous princi- ple; or it may increase the sensibility of the nerves. Smell also is only produced on drawing in the breath : when the air is returning from the lungs, it does not produce the sensation, unless the lungs, or the parts about the mouth, be diseased. In those persons who have the nose flattened, who have very small nostrils, or have the nose otherwise deformed or destroyed by accident or disease, this sense is either wholly wanting or very imperfect. When it is destroyed by palsy, or otherwise lost, the sense of touch still remains in it, as may be proved by in- troducing irritating substances. Odours are conveyed in a similar way through water to the organs of smell in fishes, as may be proved by a simple Experiment.—Put a piece of half putrid flesh or fish, which smells strongly, into a box full of holes sufficient to admit of the passage of a large eel. Place this in a pond or other piece of water where eels abound; and in a few hours, it will be filled with eels, drawn thither by the smell of the meat. It is sup- posed by the French chemists, that the moisture of the nostrils has a stronger affinity, or appetency, as Darwin would call it, for odours than it has for air, and consequently, that it seizes on the odours, separates them from the air, and allows the air to pass on after parting with them. This is pure supposition. 736 O IO O Q D O DICTIONARY OF MECHANICAL SCIENCE. Smell of Flowers in the Wight.--The air, as all must have re- marked, is better fitted when it is cool and moist, for conveying odours, than when dry and warm, as many flowers give out perfumes at night, which are not perceived by day; the nod- ding thistle (called by botanists carduus nutans) for example, the musk mallow, the sweet-scented orchis, and more particu- larly the night smelling wallflower, (called by botanists cheiran- thus tristis.) In the case of the last of these, however, the greater moistness of the air at night will not explain the pheno- menon, as the flower begins to smell about six o'clock, and in a few hours after becomes quite scentless, and remains so till the succeeding evening. Odours cannot well be classed, for ani- mal odours, such as musk, are found in vegetables, as in the musk geranium; and vegetable odours are found in metals, as the smell of garlic from heated arsenic. The blossom of the stapelia smells so like putrid flesh, that it deceives the flesh-fly so far as to make her deposit her eggs in it; and the same takes place with some species of mushroom. - Effect of Odours on the Brain—The nerves of smell, perhaps from their great exposure, and from their vicinity to the brain, are very apt when excited to act powerfully on the brain, and through it on the whole nervous system. Volatile alkali or hartshorn, as is well known, will in this way recover a person from fainting, or even prevent it; and pleasant odours, such as that of a bean-field, or of a flower garden, will sometimes induce headache. The smell of ardent spirits, of wine, and other fer- mented liquors, will in some cases produce intoxication, as if they had been taken into the stomach; and the smell of some medicines, Haller says, will act on the bowels like aperients taken by the mouth. M. Majendie is, as usual, doubtful of this explanation of the facts. He thinks in the case of the odour arising from wine, supposed to produce intoxication, that itis the actual particles of the wine floating into the air which are swal- lowed into the stomach ; and that the same holds of a man hav- ing his bowels opened by pounding a large quantity of jalap or gamboge. This, however, will not explain the instantaneous emetic effect of some nauseous smells; nor perhaps the effect of strongly odoriferous medicines in hysteric affections. Odours also act on the stomach through the influence of the associated nerves. We are told that Dumourier lived three days on the smell of hot bread ; and Lord Bacon mentions the case of a man who lived a considerable time on the smell of garlic. Any very nauseous smell also will, in weak or sickly people, produce retching and squeamishness. It is probable that odours have likewise some influence on the lungs, though this is less easy to ascertain with accuracy. Some very pun- gent odours, however, excite coughing, such as the odour, if we may call it so, arising from oxymuriatic gas, from strong cam- phor, and from turpentine. Use of Smell.—The use of the sense of smelling has certainly been much over-rated by some writers, in the instance of its guiding us to a choice of food. It acts no doubt so far in con- junction with taste, in determining what is fit to be eaten. Smell particularly warns us to avoid eating what is putrid. But man is in this much inferior to the lower animals, and has to trust both to his former experience, and to the reports of the taste, the eye, and the hand. In many cases we are even de- ceived by smell as to what is fit for food; as several things are mot anvholsome which are by no means agreeable to the smell. We may give as instances of this, salt fish, onions, garlic, mus- tard, old cheese, which are offensive to the smell of most people, though they are generally relished as food. Besides, we are fond of many smells which are produced by substances other- wise quite useless to us; such as the fragrance of lavender, thyme, ottar of roses;–in the same way as cats are fond of the smell of valerian and nepeta, though to them these are of mo use whatever as food. - Experiment.—Take a piece of fresh valerian root, or the fresh stem of catmint (called by botanists nepeta cataria), and hold it out to a cat to smell. She will be as eager to seize it as if it were a mouse, though she wiłł not eat it. By this means you may cause a cat to follow you to any distance you please. The experiment is not found to succeed with very young eats, either because they are deficient in smell while young, or because the influence of the odours depends on some sexual feeling. - Chemists long thought that the odoriferous part of bodies formed a peculiar principle, distinct from all the other substan- ces entering into their composition, and which they called aroma. Most bodies allow excessively minute particles to be detached and diffused in the atmosphere, which becomes loaded there- with, and sometimes carries, them to a considerable distance, as well as conveys them to the olfactory organs. These parti. cles constitute odours; and the infinite variety of them from different substances exhaled, renders it extremely difficult to classify them; but in a work of this description their classifi- cation is wholly unnecessary. Bodies whose particles are fixed, are termed inodorous. The odour of every body is peculiar to itself, yet there is a great difference among them, as to the mode in which the odours are detached; with some it is only when they are heated, with others only when rubbed ; some give only a very faint, others a very strong smell. Such is the tenuity of odorous particles, that a body may, during a long time, disengage them without sensible diminution of weight. - The atmosphere becomes loaded with the greater quantity, the warmer and the more moist it is. We know that in a flower garden, the air is never loaded with fragrant odours, nor is the smell ever the source of pleasing enjoyment, so much as in the morning, when the dew is evaporating by the rays of the sun. By the smell we perceive the odorous effluvia taken in by inspi- ration, and principally applied to the Schneiderian membrane, causing very delicate and delightful impressions; and no sen- sations are remembered in so lively a manner as those of pecu- liar odours. Wonderful, indeed, is the variety of odours in the vegetable kingdom, and the sweet perfume of flowers is no less remarkable than the brilliancy of their lovely hues. Indeed, there is as much variety in the odours of flowers as in the flowers themselves. The extreme subtlety of the particles which flowers exhale, is such, that the smell of the rosemary which grows in Provence reaches twenty miles beyond sea; and a grain of amber can fill a room twenty feet square, and fifteen feet high, with its perfume. Odorous bodies may be regarded as fugitive and tenacious; for the most pungent usually evaporate most speedily, as ether, alcohol, the spirituous tinctures, and essential volatile oils. They are likewise —musky, as those of musk and the rose, cha- racterized by their tenacity;-aromatic, as the smell of the lau- rel ;-fragrant, as the lily, saffron, and the jasmine, whose smell is very fugitive ;-fetid, as of valerian and fungi;-virulent, as of poppies and opium ; spermatic, approaching that of garlic ;- pungent, as of mustard;—nauseous, as of gourds, melons, cucum- bers, and most cucurbitaceous plants;–muriatic, as that of saline substances: distinguishable further, as weah, strong, agreeable, and disagreeable. In most cases, however, an odour is described by comparing it to that of some well-known sub- Stance. - Odours are supposed to possess nutritive, medicinal, and even poisonous properties; but, in the cases which have caused these opinions, probably the influence of odours has been con- founded with the effects of absorption. A man after pounding jalap for some time, will be purged as if he had swallowed it. These effects ought not to be ascribed to the odour, but to the particles diffused in the atmosphere, and introduced into the circulation, either with the saliva, or the air which he inspired: to the same cause must be attributed the intoxication of per- sons exposed for some time to the vapour of spirituous liquors. Liquids, vapours, and gases, with many solids, reduced to an impalpable or even coarser powder, have the power like odours of affecting the organs of smelling. But the mechanism of their action is rather different;-the air is the ordinary vehi- cle of odours, and transports them to a distance, as well as to the pituitary membrane which lines the nasal canals, but which is only affected by odours, however, when inhaled by the nos- trils. Hence, when any odour is agreeable or grateful, we employ short and frequent inspirations, that the whole of the air received into the lungs may pass through the nasal fossae ; and, on the contrary, we breathe through the mouth, or sus- pend respiration, for a time, when the odour is disagreeable. Bodies reduced to a coarse powder, have also a strong action ! on the pituitary membrane; their first action is painful; but eustom at length converts the pain into a pleasure, as we see O F F O I L 737 DICTIONARY OF MECHANICAL SCIENCE. in the example of tobacco. The odours in the upper part of the nasal cavities are more easily and strongly perceived; hence we modify inspiration so that the air may be directed towards this point, when we wish to smell a body strongly or accurately; hence also, snuff-takers endeavour to carry it towards the vault of the nostrils and olfactory nerves; the minute ramifications of which are distributed throughout the whole concavity of the former. Wonderful, indeed, is the care of nature in providing the nasal fossae with a covering of hair to intercept the parti- cles of odoriferous bodies from attacking the nerves too preci- pitately, and communicating impressions to the brain, till it is as it were previously prepared to be excited by them. But, odours may be likewise propagated under an exhausted receiver; and certain bodies project odorous particles with some force. They may be attached to, or combined with, many liquids and solids, to fix or preserve them for any length of time. OECUMENICAL, signifies the same with general, or univer- sal, as oecumenical council, bishop, &c. OEDEMA, in Surgery, a phlegmatic tumour, attended with paleness and cold, which obtains a place in any part of the body, but particularly the feet. OENOTHERA, Tree Primrose, a genus of plants belonging to the octandria class, and in the natural method ranking under the 17th order Calycanchemae. OESOPHAGUS, the gula, or gullet, is a membranaceous canal, reaching from the fauces to the stomach, and conveying into it the food taken in at the mouth. OESTRUS, GAD FLY, a genus of insects of the order diptera, extremely troublesome to horses, sheep, and cattle, depositing their eggs in different parts of the body, and producing very painful tumours, and sometimes death. The larvae are without feet, short, thick, and annulate, and often furnished with small hooks. There are twelve species named, from the animals which they infest. - OFFENCE. Capital offences are those for which the offender loses his life; not capital where the offender, may lose his lands and goods, be fined, or suffer corporeal punishment, or both, but which are not subject to the loss of life. OFFICE, that function, by virtue of which a person has some employment in the affairs of another. An office is a right to exercise any public or private employment, and to take the fees and emolument belonging to it, whether public, as those of magistrates; or private, as of bailiffs, receivers, &c. To offer money to procure the reversion of an office in the gift of the crown, is a misdemeanor at common law, and punishable by information; and even the attempt to induce, under the in- fluence of a bribe, is criminal, though never carried into exe- cution. An instance of which occurred under the administra- tion of Mr. Addington, who prosecuted a tinman for offering him a sum of money for a place in the customs. Any contract to procure the nomination to an office, not within the statute of 6 Edward VI. is defective on the ground of public policy; and the money agreed to be given is not recoverable. OFFICER. The great officers of the crown, or state, are the Lord High Steward, the Lord High Chancellor, the Lord High Treasurer, the Lord High President of the Council, the Lord Privy Seal, the Lord Chamberlain, the Lord High Consta- ble, the Earl Marshal. OFFICERS, Field, are such as command a whole regiment, as the colonel, lieutenant-colonel, and major. OFFICERS, General, are those whose command extends to a body of forces, composed of several regiments: such are ge- nerals, lieutenant-generals, major-generals, and brigadiers. OFFICERS, Staff, are such as, in the king's presence, bear a white staff, or wand; and at other times, on their going abroad, have it carried before them by a footman, bare-headed; such are the Lord Steward, Lord Chamberlain, Lord Treasurer, &c. OFFICERS, Commission, are those appointed by the king's com- mission: such are all from the general to the cornet inclusive, who are thus denominated in contradistinction to warrant offi- cers, who are appointed by the colonel’s or captain's warrant, as quarter-masters, sergeants, corporals, and even chaplains and surgeons. OFFIceRs, Subaltern, are all who administer justice in the name of subjects; as those who act under the Earl Marshal, 76. Admiral, &c. In the army the subaltern officers are the lieute- nants, cornets, ensigns, sergeants, and corporals. 4. OFFICIAL, by the ancient law, signifies him who is the minis- ter of, or attendant upon, a magistrate. In the cannon law, it is especially taken for him to whom any bishop generally com- mits the charge of his spiritual jurisdiction ; and in this sense there is one in every diocese called officialis principialis, whom º: and statutes of this kingdom call chancellor. 32 Hen. III. 15. OFFICINA SCULPTORIS, the Sculptor's Shop, is a small constellation, composed by M. La Caille on the south of Cetus, and containing, acording to Flamstead, twelve stars, spread over a considerable space of the firmament, but none of them exceeding the fifth magnitude. OFFING, or OFFIN, that part of the sea a good distance from shore, where there is deep water, and no need of a pilot to con- duct the ship. OFFSETS, in Gardening, those young shoots that spring from the roots of trees or plants, which being carefully separated and planted in a proper soil, serve to propagate the species. OFFSETs, in Surveying, are those short perpendiculars that are measured on the sides of irregular figures, for the more accurate determination of the area. - OFFSET Staff, a staff or rod used in surveying for measuring effects. It is commonly made of lightwood ten links in length, divided and numbered from one end to the other. OFFWARD, the situation of a ship which lies aground, and leans from the shore: thus they say, “the ship heels offward,” when being aground she heels towards the water side; and “the ship lies with her stern to the offward, and the head to the shore- ward,” when her stern is towards the sea and head to the shore. OGEE, in Architecture, or O, G, a moulding consisting of two members; one concave and the other convex, or of a round and hollow like an S. OGIVE, in Architecture, an arch or branch of a gothic vault, which, instead of being circular, passes diagonally from one angle to another, and forms a cross with the other arches. The middle, when the ogives cross each other, is called the key, be- ing cut in a rose or cul de lamp. The members or mouldings of the ogives are called nerves, branches, veins; and the arches which separate the ogives, double arches. IL, an unctuous inflammable substance, extracted from several natural bodies, whether animal or vegetable, as whale oil, olive oil, &c. - Oil obtained from Rape Seed by Pressure.—This is used in large quantities by clothiers and others, and likewise in medicine, and frequently for making the soap called green soap. It is also useful for various purposes in domestic life, and particu- larly for burning in lamps; but it is apt to become rancid, though there are means of purifying it. After the oil has been extracted, the refuse is called oil-cake, and is employed for the fattening of oxen, and in Norfolk is sometimes broken to pieces and strewed on the land as manure. The roots of rape plants may be eaten like turnips, but they have a stronger taste. The stalks of haulm, if strong, may be advantageously employed for the enclosing fences of farm yards. They are, however, gene- rally burnt, and in some parts of the country the ashes, which are equal to the best pot-ashes, are collected together and sold. To Prepare an Oil for Clocks and other delicate Machinery.— The oil for diminishing friction in delicate machines, ought to be completely deprived of every kind of acid and mucilage : and to be capable of enduring a very intense degree of cold without freezing. In fact, it ought to consist entirely of elaine or the oily principle of solid fat, and to be perfectly free from stearine or solid fat. Now it is not a difficult matter to extract the elaine from all the fixed oils, and even from seeds, by the process recommended by Chevreul, which consists in treating the oil in a mattrass with seven or eight times its weight of alcohol till boiling. The liquid is then to be decanted, and ex- posed to the cold, the stearine will then separate from it in the form of a crystallized precipitate. The alcoholic solution is after- wards to be evaporated to a fifth part of its volume, and the elaine will then be obtained, which ought to be colourless, insi- pid, without smell, and incapable of altering the colour of the infusion of litmus or turnsole, and having the consistence of pure * olive oil. 788 Q I L. G. I. L. DICTIONARY OF MECHANICAL SCIENCE. OIL, MILL. This machine is used for expressing their oils from fruits, grains, &c.; and the following description, which is given in Dr. Gregory's. Mechanics, is that of a Dutch mill employed for grinding and expressing lint and rape seed, &c. The original mill is put in motion, we believe, by wind; the Doctor, however, employs water as a first mover. In the Plate OIL MILL, &c, fig. A, 1 is the elevation of a wheel, over or under shot, as the situation may require. 2, the bell-metal socket, supported by masonry, for receiving the outer gudgeon of the water wheel. 3, the water course. |Fig. B. 1, a spur wheel upon the same axis, having 52 teeth. 2, the trundle that is driven by No. 1, and has 78 staves. 3, The wallower, or axis for raising the pestles. It is furnished round its circumference with wipers for lifting the pestles, so that each may fall twice during one turn of the , water wheel, that is, three, wipers for each pestle. 4, a frame of timber, carrying a concave half-cylinder of bell metal, in which the wallower (cased in that part with iron plates) rests and turns round. 5, masonry supporting the inner gudgeon of the water wheel, and the abovementioned frame. 6, gudgeon of the wallower, which bears against a bell-metal step fixed in the wall. This double support of the wallower is found to be necessary in all mills which drive a number of heavy stampers. Fig. C is the elevation of the pestle and press frame, their furnitures, the mortars, and the press pestles. 1, the six pestles. 2, cross pieces, between the two rails of the frame, forming, with these rails, guides for the perpendicular motion of the pestles. 3, the two rails. The back one is not seen. They are checked and bolted into the standards No. 12. 4, the tails of the lifts, corresponding to the wipers upon the wallower. See the article WIPER. 5, another rail in front, for carrying the detents which hold up the pestles when not acting. It is marked 14 in fig. M. 6, a beam a little way behind the pestles. To this are fixed the pulleys for the ropes which lift and stop the pestles. It is represented by 16 in fig. M. 7, the said pulleys, with their ropes. 8, the driver, which strikes the wedge that presses the oil. 9, the discharger, a stamper which strikes upon the inverted wedge, and loosens the press. 10, the lower rail with its cross pieces, forming the lower guides of the pestles. 11, a small cog wheel upon the wallower, for turning the spatula, which stirs about the oil seed in the chauf- fer pan. It has 28 teeth, and is marked No. 6 in fig. M. 12, the four standards, mortised below into the block, and above. into the joists and beams of the building. 13, the six mortars hollowed out of the block itself, and in shape pretty much like a kitchen pot. 14, the feet of the pestles, rounded into cylin- ders, and shod with a great lump of iron. 15, a board behind the pestles, standing on its edge, but inclining a little back- wards. There is such another in front, but not represented here. These form a sort of trough, which prevents the seed from being scattered about by the fall of the pestles, and lost. 16, the first press box, (also hollowed out of the block,) in which the grain is squeezed, after it has come for the first time from below the millstones. 17, the secónd press box, at the other end of the block, for squeezing the grain after it has passed a second time under the pestles. 18, frame of timber for supporting the other end of the wallower, in the same man- ner as at No. 4, fig. B. 19, small cog wheel on the end of the wallower, for giving motion to the millstones. It has 28 teeth. 20, gudgeon of the wallower, bearing on a bell-metal socket fixed in the wall. 21, vessels for receiving the oil from the press boxes. Fig. D. Elevation and mechanism of the millstones. 1, up- right shaft, carrying the great cog wheel above, and the runner millstones below in their frame. 2, cog wheel of 76 cogs, driven by No. 19, of fig. C. 3, the frame of the runners. 4, the innermost runner, or the one nearest the shaft. 5, outermost ditto, being further from the shaft. 6, the inner rake, which collects the grain under the outer runner. 7, the outer rake, which collects the grain under the inner runner. In this man- ner the grain is always turned over and over, and crushed in every direction. The inner rake lays the grain in a slope, of which fig O is a section; the runner flattensit, and the second rake lifts it again, as is marked in fig, P; so that every side of a grain is presented to the millstone, and the rest of the legger or nether millstone is so swept by them, that not a single grain is left on any part of it. The outer rake is also furnished with a rag of cloth, which rubs against the border or hoop that sur. rounds the mether millstone, so as to drag out the few grains. which might otherwise remain in the corner. 8, the ends of the iron axle which passes through the upright shaft, and through the two runners. Thus they have two motions: 1mo, a rotation round their own axis; 2do, that by which they are carried round upon the nether millstone on which they roll. The holes in these millstones are made a little wide ; and the holes in the ears of the frame, which carry the ends of the iron axis, are made oval up and down. This great freedom of motion is necessary for the runner millstones, because fre- quently more or less of the grain is below them at a time, and they must therefore be at liberty to get over it without strain- ing, and perhaps breaking, the shaft. 9, the ears of the frame which lead the two extremities of the iron axis. They are mortised into the under side of the bars of the square frame, that is carried round with the shaft. 10. The border or hoop which surrounds the nether millstone. 11 and 12, the nether millstone, and masonry which supports it. Fig. K. Plan of the runner millstones, and the frame which carries them round. 1, 1, are the two millstones. 3, 3, 3, 3, the outside pieces of the frame. 4, 4, 4, 4, the cross bars of the frame which embrace the upright shaft 5, and give motion to the whole. 6, 6, the iron axis upon which the runners turn. 7, the outer rake. 8, the inner ditto. Fig. L represents the nether millstone seen from above. 1, the wooden gutter, which surrounds the nether millstone. 2, The border or hoop, about six inches high all round, to prevent any seed from being scattered. 3, an opening or trap door in the gutter, which can be opened or shut at pleasure. When open, it allows the bruised grain collected in and shoved along the gutter by the rakes to pass through into troughs placed below to receive it. 4, portion of the circle described by the outer runner. 5, portion of the circle described by the inner one. By these we see that the two stones have different routes round the axis, and bruise more seed. 6, the outer rake. 7, the inner ditto. 8, the sweep, making part of the inner rake, occasionally let down for sweeping off all the seed when it has been sufficiently bruised. The pressure and action of these rakes is adjusted by means of wooden springs, which cannot be easily and distinctly represented by any figure. The oblique position of the rakes (the outer point going foremost) causes them to shove the grain inwards or toward the centre, and at the same time to turn it over, somewhat in the same manner as the mould board of a plough shoves the earth, to the right hand, and partly turns it over. Some mills have but one Sweeper, and, indeed, there is great variety in the form and construction of this part of the machinery. Fig. M, profile of the pestle frame. 1, section of the horizon- tal shaft. 2, three wipers for lifting the pestles. See WIPER. 3, little wheel of 28 teeth, for giving motion to the spatula. 4, another wheel, which is driven by it, having 20 teeth. 5, hori- Zontal axle of ditto. 6, another wheel on the same axle, hav- ing 13 teeth. 7, a wheel upon the upper end of the spindle, having 12 teeth. 8, two guides, in which the spindle turns freely, and so that it can be shifted higher and lower. 9, a lever, moveable round the piece No. 14, and having a hole in it at 9, through which the spindle passes, turning freely. The spindle has in this place a shoulder, which rests on the border of the hole 9; so that by the motion of this lever the spindle may be disengaged from the wheel work at pleasure. This motion is given to it by means of the lever 10, 10, moveable round its middle. The workman employed at the chauffer pulls at the rope 10, 11, and thus disengages the spindle and spatula. 11, a pestle seen sidewise. 12, the lift of ditto. 13. the upper rails, marked No. 3 in fig, C. 14, the rail, marked No. 5 in fig. C. To this are fixed the detents, which serve to stop and hold up the pestles. 15, a detent, which is moved by the rope at its outer end. 16, a bracket behind the pestles, having a pulley, through which passes the rope going to the detent 15. 17, the said pulley. 18, the rope at the workman’s hand, passing through the pulley 17, and fixed to the end of the detent 15. This detent naturally hangs perpendicular, by its own weight. When the workman wants to stop a pestle, he pulls at the rope 18, during the rise of the pestle. When à // // / // - // // ºr 2% %// º/ - * D. ** 2 º ºd |- §， |||| ！La º 1 2 3 4 5 & 7 & 9 10 1/ 12 /3 24 25 16, 1715 º żo 21 22 23 24 ^- Aº. Aºy O. º, 2 /// Zºrºazzaze, wee &nnon Zºo, · rº |r ---- |- |- |- |- |- |- |- |- |- |- |- |- |- * |- ºut lººd by ºn ºn O I L O I L. 739 DICTIONARY OF MECHANICAL SCIENCE. this is at its greatest height, the detent is horizontal, and pre- vents the pestle from falling by means of a pin projecting from the side of the pestle, which rests upon the detent, the detent itself being held in that position by hitching the loop of the rope upon a pin at the workman's hand. 19, the two lower rails, marked No. 10, fig. C. 20, Great wooden, and sometimes stone, block, in which the mortars are formed, marked No. 21 in fig. C. 21, vessel placed below the press boxes for receiving the oil. 22, Chauffer, or little furnace, for warming the bruised grain. 23, backet in the front of the chauffer, tapering down- wards, and opening below in a narrow slit. The hair bags, in which the grain is to be pressed after it has been warmed in the chauffer, are filled by placing them in this backet. The grain is lifted out of the chauffer with a ladle, and put into these bags; and a good quantity of oil runs from it through the slit at the bottom into a vessel set to receive it. 24, the spatula attached to the lower end of the spindle, and turning round' among the grain in the chauffer-pan, thus preventing it from sticking to the bottom or sides, and getting too much heat. The first part of the process at an oil-mill is bruising the seed under the runner stones.* That this may be more expe- ditiously done, one of the runners is set about two-thirds of its own thickness nearer the shaft than the other. Thus they have different treads; and the grain, which is a little heaped towards the centre, is thus bruised by both. The inner rake gathers it up under the outer stone into a ridge, of which the section is represented in fig. O. The stone passes over it, and flattensit. It is gathered up again into a ridge, of the form of ſig. P, under the inner stone, by the outer rake, which consists of two parts. The outer part presses close on the wooden border which surrounds the nether stone, and shoves the seed obliquely inwards, while the inner part of this rake gathers up what had spread toward the centre. The other rake has a joint near the middle of its length, by which the outer half of it can be raised from the nether stone, while the inner half continues pressing on it, and thus scrapes off the moist paste. When the seed is sufficiently bruised, the miller lets down the outer end of the rake. This immediately gathers the whole paste, and shoves it obliquely outwards to the wooden rim, where it is at last brought to a part that is left unboarded, and it falls through into troughs placed to receive it. These troughs have holes in the bottom, through which the oil drips all the time of the operation. This part of the oil is directed into a particular cistern, being considered as the purest of the whole; having been obtained, without pressure, by the mere breaking of the hull of the seed. In some mills this operation is expedited, and a much greater quantity of this best oil is obtained, by having the bed of masonry which supports the legger formed in a little furnace, and gently heated. But the utmost care is necessary to pre- vent the heat from becoming considerable. This, enabling the oil to dissolve more of the fermentable substance of the seed, exposes the oil to the risk of growing soon very rancid; and, in general, it is thought a hazardous practice, and the oil does not bring so high a price. ... When the paste comes from under the stones, it is put into the hair bags, and subjected to the first pressing. The oil thus obtained is also esteemed as of the first quality, scarcely inferior to the former, and is kept apart; (the great oil cistern being divided into several portions by partitions.) The oil cakes of this pressing are taken out of the bags, broken to pieces, and put into the mortars for the first stamping. Here the paste is again broken down, and the parenchyma of the seed reduced to a fine meal. Thus free egress is allowed to the oil from every vesicle in which it is contained; but it is now rendered much more clammy, by the forcible mixture of the mucilage, and even of the finer parts of the meal. When sufficiently pounded, the workman stops the pestle of a mor- tar when at the top of its liſt, and carries the contents of the mortar to the first chauffer pan, where it is heated to about the * * We are told, that in a mill at Reichenhoffen, in Alsace, a considerable improvement has been made by passing the seed between two small iron rollers, before it is put under the millstones. A great deal of work is said to be saved by this preliminary operation, and finer oil produced; which we think very probable. The stamping and pressing go on as in other mills. temperature of melting bees’ wax, (this, we are told, is the test,) and all the while stirred about by the spatula. From thence it is again put into hair bags, in the manner already described ; and the oil which drips from it during this opera. tion is considered as the best of the second quality, and in some mills is kept apart. The paste is now subjected to the second pressing, and the oil is that of the second quality. All this operation of pounding and heating is performed by one workman, who has constant employment by taking the four mortars in succession. The putting into the bags, and con- ducting of the presses, gives equal employment to another workman. - In the mills of Picardy, Alsace, and most of Flanders, the operation ends here ; and the produce from the chauffer is increased, by putting a spoonful or two of water into the pan among the paste. But the Dutch take more pains. They add no water to the paste of this their first stamping. They say that this greatly lowers the quality of the oil. The cakes which result from this pressing, and are there sold as food for cattle, are still fat and softish. The Dutch break them down. and subject them to the pestles for the second stamping. These reduce them to an impalpable paste, stiff like clay. It is lifted out, and put into the second chauffer pan; a few spoonfuls of water are added, and the whole kept for some time as hot as boiling water, and carefully stirred all the while. From thence it is lifted into the hair bags of the last press, subjected to the press; and a quantity of oil of the lowest quality is obtained, sufficient for giving a satisfactory profit to the miller. The cake is now perfectly dry and hard, like a piece of board, and is sold to the farmers. Nay, there are small mills in Holland which have no other employment than extracting oil from the cakes which they purchase from the French and Brabanters; a clear indication of the superiority of the Dutch practice. The nicety with which that industrious people conduct all their business is remarkable in this manufacture. In their oil cistern, the parenchymous part, which unavoidably gets through, in some degree, in every operation, gradually sub- sides; and the liquor, in any division of the cistern, comes to consist of strata of different degrees, of purity. The pumps, which lift it out of each division, are in pairs; one takes it up from the very bottom, and the other only from half depth. The last only is barreled up for the market, and the other goes into a deep and narrow cistern, where the dreg again subsides, and more pure oil of that quality is obtained. By such careful and judicious practices, the Dutch not only supply themselves with this important article, but annually send considerable quantities even into those provinces of France and Flanders, where they bought the seed from which it was extracted. When we reflect on the high price of labour in Holland, on the want of timber for machinery, on the expense of building in that country, and in the enormous expense of windmill machinery, both in the first direction and the subsequent wear and tear, it must be evident, that oil mills erected in England on water falls, and after the Dutch manner, cannot fail of being a great national advantage. The chatellanie or seigneurie of Lille, alone makes annually between 30,000 and 40,000 barrels, each containing about 26 gallons. What is here delivered is only a sketch. Every person acquainted with machinery will understand the general move- ments and operations. But the intelligent mechanic well knows, that operations of this kind have many minute circum- stances which cannot be described, and which, nevertheless, may have great influence on the whole.—Dr. Gregory's Ma- chimes, vol. 2. OIL GAS, If oil, tallow, or wax, be let fall upon red-hot iron, or made to pass through red-hot iron pipes, it will be re- solved into a combustible gas. The fact was long known to chemists; and after the success of lighting by coal-gas was made apparent. Messrs. Taylor and Martineau contrived an ingenious apparatus for producing oil gas on a large, scale, as a substitute for candles, lamps, and coal gas. Oil gas has several advantages over coal gas. It has no unpleasant smell in a room; it does not require the expense of being purified by lime: it will not injure in the least, books, pictures, or fine fur- niture ; it has no corrosive effects on the pipes which convey it. It is far more economical than argand lamps, or mould or 740 O M N O P E DICTIONARY OF MECHANICAL SCIENCE. wax candles. It gives a very bright light; and one cubic foot of oil gas will yield much more light than the same quantity of coal gas. This last is a great advantage, where saving of room is important. - OLBERS, a name sometimes given to the planet Pallas, discovered by Dr. Olbers, March 28th, 1802; but since the discovery of a second planet by the same astronomer, viz. Vesta, March 29th, 1807, the name Olbers is usually changed for that of Pallas, to prevent confusion between the two. See PALLAs. * OLEA, Olive, a genus of the diandria monogynia class and order. Natural order of sepiariae. Jasmineae, Jussieu. Es- sential character: corolla four-cleft; with subovate segments; drupe one-seeded. There are seven species. The olive seldom becomes a large tree; two or three stems frequently rise from the same root, from twenty to thirty feet in height, putting out branches almost their whole length, covered with a grayish bark. See OLIve below. * OLEFIANT GAS. This gas differs from the common gas in this, that it consists of one prime of carbon and one of hydro- gen, instead of one prime of carbon and two of hydrogen. OLEIC ACID, is an oil obtained from potass and hogs' lard saponified, which has the property of saturating bases, and forming neutral compounds. - OLERON LAws, laws relating to maritine affairs, and so called, because made when king Richard I. was at the Isle of Oleron, in Aquitaine. OLFACTORY Nerves, the first pair of the head, so called from their being the immediate instruments of smelling. OLIBANUM. A gum resin, the product of the Juniperus Lycia, brought from Turkey and the East Indies usually in drops or tears. The best is of a yellowish white colour, solid, liard, and brittle : when chewed for a little time, it renders the spittle white, and impresses an unpleasant bitterish taste; laid on burning coals, it yields an agreeable smell. OLIGARCHY, a form of government wherein the admis- tration of affairs is lodged in the hands of a few persons. OLIVE. The olive in all ages has been held in peculiar esti- mation, as the bounteous gift of Heaven ; it is still considered as emblematic of peace and plenty ; the great quantity of oil which it produces in some countries, effectually realizes the latter of these blessings Unripe olives pickled, especially the Provence and Lucca sorts, are to many persons extremely grateful ; they are supposed to promote digestion. OLIVINE, in Mineralogy, a species of the chrysolite family, found in the form of crystals, chiefly in basalt; colour between asparagus and olive green; specific gravity 3:2. OLLARIS LAPIS, or Potstone, found abundantly near the lake of Como, is made into pots, and is also employed in Green- land. Its constituents are silica 39, magnesia 16, oxide of iron 10, carbonic acid 20, water 10. It occurs in beds of primitive slate. I OLYMPIAD, in Chronology, a period of four years, by which the Greeks reckoned their time; being thus called from the Olympic games held every fourth year, during five days near the summer solstice, on the banks of the river Alpheus, near Olympia, a city of Elis. The first Olympiad began the year 3938 of the Julian period, corresponding to 776 years before Christ. The computation by these games ended with the 404th, being the 440th of the present Christian era. OMBROMETER, a name given by Mr. Pickering to the pluviometer, or rain gauge. OMNIUM, a term in familiar use among stock-brokers and speculators in the funds, to express the whole of the articles which the subscribers to a loan receive from government. Thus, if the subscribers, according to their agreement with govern- ment, are to have for every hundred pounds advanced a certain sum in 3 per cent, consols, a further sum in 4 per cents, and a proportion of the long annuities, the blank receipts which they receive for making the instalments on the several articles, are, when disposed of, independent of each other, as the 3 per cent. consols only, called scrip; when the receipts are sold together as originally received, they are usually called omnium. As the omnium of every loan is the subject of extensive speculations, it generally is liable to considerable variations with respect to its current price, sometimes selling at a high premium, at other times at a discount, according to the circumstances which take place between the agreement for the loan and the day fixed for paying the last instalment. à . . . OMPHACITE, a mineral of a leek green colour, found in Carinthia. - - - OMPHALOPTER, a name sometimes given to a convex lens. ONION, The Common, known by its cylindrical hollow leaves, and swelling pipy stalk, is a bulb that does not throw out offsets. Onions are propagated by seeds which are sown in spring; and the bulbs or roots arrive at perfection in the autumn. The whole plant when young is eaten as salad. Onions generally cease to grow towards the middle of August, the stalks and leaves at that time shrinking and turning brown. Shortly after this they must be drawn out of the earth; the . tops and blades must be cut off; and the roots dried, eitlier in a warm place, or by exposure to the sun. Spanish onions are of large size, and flattened shape; and Portugal onions are large, handsome bulbs, of roundish form. The kinds of onions in cultivation are, the Deptford, the Reading, the white Spanish, the Portugal, the Globe, and the Silver-skinned. All these varieties are usually sown in the spring of the year, and are good either eaten in their young state, or after they are dried in the winter. The silver-skinned kind is mostly in use for pickling. The globe and Deptford kinds are remarkable for keeping late in the spring. A portion of all the other sorts should be sown, as they are all very good, and some kinds will keep when others will not. By the common people, onions are frequently eaten raw with their food. This has particularly been the case, and from time immemorial, with the inhabitants of Egypt. By stimulating the stomach they are supposed to favour digestion; and some persons have imagined that they possess a large portion of alimentary matter : while others say that they afford little or no nourishment, and that, when eaten freely, they produce flatulencies, occasion thirst, headaches, and turbulent dreams. They have so much acrimony as gene- rally to aſſect the breath for many hours; but when boiled or roasted this is in great measure dissipated, and they then ex- hibit some sweetness, with a considerable portion of mucilagi- nous matter. Onions are of great use in several culinary pre- parations, but particularly in soup and pickles. They are employed in medicine chiefly as poultices for swellings; and have been recommended, by some persons, to be rubbed on bald parts of the head, to promote the growth of the hair. ONOCLEA, a genus of plants belonging to the cryptogamia class and order of Filices. ONONIS, a genus of plants belonging to the diadelphia class. - ONOPERDUM, a genus of plants belonging to the synge- nesia class, and in the natural method ranking under the 49th order, Compositae. ONOSMA, a genus of plants belonging to the pentandria class, and in the natural method ranking under the 41st order, Asperifoliae. ONYX. A chalcedony with alternate layers of white, black, and dark brown. OPACITY, that quality of bodies which renders opaque, in contradistinction to transparency. OPAKE, or OPAQUE, not translucent nor transparent ; or, that which prevents the free admission of the rays of light. OPAL, in Mineralogy, a species of the quartz family, found in many parts of Europe, especially in Hungary. When first dug out of the earth it is soft, but it hardens and diminishes in bulk by exposure to the air. The specific gravity varies from 1.9. to 2-5. There are four sub-species, viz. the precious, the common, the semi, and the wood opal. - OPERA, a dramatic composition set to music, and sung on the stage, accompanied with musical instruments, and enriched with magnificent dresses, machines, and other decorations. OPERA Glass, in Optics, so called from its use in theatres, &c. it is sometimes called a “ diagonal perspective,” from its con- struction. It consists of a tube about four inches long, in each. side of which there is a hole exactly against the middle of a plane mirror, which reflects the rays falling upon it to the con- vex glass, through which they are refracted to the concave eye- glass, whence they emerge parallel to the eye at the hole in: the tube. This instrument is not intended to magnify objects them o P H O P T 741 DICTIONARY OF MECHANICAL SCIENCE. more than about two or three times. The peculiar artifice is to view a person at a small distance, so that no one shall know who is observed; for the instrument points to a different object from that which is viewed; and as there is a hole on each side, it is impossible to know on which hand the object is situated which you are looking at. . . - g OPHTHALMIA, in Medicine, an inflammation of the Inem- branes which invest the eye. - . OPHIDIUM, a genus of fishes in the order Apodes. } OPHIOGLOSSUM, Adder's Tongue, a genus of plants be- longing to the cryptogamia class, and to the order Filices. OPHIORHIZA, a genus of plants belonging to the pentan- dria class, and in the natural method ranking under the 47th order, Stellatae. - 4. - OPHIOXYLON, a genus of plants belonging to the poly- gamia class, and in the natural method ranking with those of which the order is doubtful. - - OPHIRA, a genus of plants in the octandria class. OPHIUCHUS, or SERPENTARIUs, and Serpens, one of the old constellations, and which was anciently called AEsculapius. Its title of Serpentarius is due to the skill of Apollo's son in having restored Hippolytus to life, the Serpent entwined around Ophiuchus being the symbol of medicine, and of the gods who presided over this art; but the reptile may also be the symbol of prudence and vigilance. . . . The Boundaries and Contents.--This constellation, occupying a large portion of the heavens south of Hercules, is usually divided into two parts, one being assigned to Ophiuchus, and the other to Serpens. On the east it is bounded by Taurus Poniatowski and Scutum, south by Scorpio, and west by Böotes. The head of the Serpent is easily distinguished by some stars of the third and fourth magnitudes, which are found directly midway under Corona Borealis. They form, with y and 3 of Hercules, the figure of a Y, the tail of which goes towards the south. Another of these, known as a, of the second magnitude, shines very brightly, and forms the heart of the Serpent. The other stars become mixed with those in Ophiuchus. There are 134 stars in this constellation, of which two are of the second, fourteen of the third, thirteen of the fourth magnitude, &c. The most brilliant among them is a Ras Alhague, having 261°38'32" right ascension, and 12°42' 6" of north declination. This star appears E.N.E. # E. point of the compass, at London, and it rises and culminates as follows: Meridian Altitude, 51°11'6" N. MonTH. | RISEs. CULM. MONTH. RISES. CULM. ho. Ini. ho. mi. ho. mi. ho. mi. Jan. 3 35 M. 10 44 M July 3 45 A. | 10 44 A. Feb. 1 16 M. 8 20 M Aug. 1 45 A. | 8 45 A. Mar. 11 35 A. | 6 34 M. Sept. 11 46 M. 6 46 A. April 9 40 A. 4 35 A. Oct. 9 45 M. 5 0 A. May 7 5.5 A, 2 50 A Nov. 7 50 M. 3 5 A. June 5 45 M. | 12 45 M. Dec, 5 45 M. 12 55 M. OPHRYS, Twyblade, a genus of plants belonging to the gynandria class, and in the natural method ranking under the 7th order, Orchideae. OPHRYS API ferA, that is to say, Bee Ophrys, tanks among the few plants that are more generally admired than all the Orchideae for their singular beauty and uncommon structure. . The one in question so very much resembles the humble-bee in appearance, that I have known persons mistake this ſlower for the animal. It is unfortunate for the amateurs of gardening, that most plants of this tribe are difficult of propagation, and are not of easy culture. Botanists sometimes succeed with this and other species by the following method:—To take up the roots from their native places of growth as early as they can be found, and then to procure some chalk and sift it through a fine sieve, and also some good tenacious loam ; mix both in equal quantities in water; a large garden-pot should then be filled with some rubble of chalk, about one-third deep, and then the above compost over it, placing the roots in the centre, at the usual depth they grew before. As the water drains away, the loam and chalk will become fixed closely round the bulbs, and they will remain alive and grow. By this method I have cultivated these plants for some years together. In this way all those kinds growing in chalk may be made to s”. but such as the Orchis morio, maculata, and pyramidalis, may be grown in loam alone, planted in pots in the common way. Care should be taken that the pots in which they are planted are protected from wet and frost in the winter season. OPIUM, obtained from poppy seeds, is procured from Tur- key, and is also now produced to a large amount in India, and is exported to China. It is a powerful narcotic. OPiuM, in Chemistry and Medicine, an inspissated gummy juice, which is obtained from the head of the “papavera somni- ferum.” It is imported from Persia, Arabia, and other warm parts of Asia, in flat cakes covered with leaves to prevent their sticking together. It has a reddish brown colour, and strong peculiar smell; its taste at first is nauseous and bitter, but this ºn becomes acrid, and produces a slight warmth in the mouth. OPOBALSUM. The most precious of the balsams is that commonly called Balm of Gilead, Opobalsamum, Balsamaeleon, Balsamum verum album, AEgyptiacum, Judaicum, Syriacum e Mecca, &c. This is the produce of the amyris opobalsamum, L. The true balsam is of a pale yellowish colour, clear and transparent, about the consistence of Venice turpentine, of a strong, penetrating, agreeable, aromatic smell, and a slightly bitterish pungent taste. - OPODELDOC. A solution of soap and alcohol, with the addition of camphor, and volatile oils. It is used externally against rheumatic pains, sprains, bruises, and other like com- plaints. . . - - ... " OPOPONAX. A concrete gummy resinous juice, obtained from the roots of an umbelliferous plant, the pastinaca opopo- . nax, which grows spontaneously in the warmer countries, and bears the cold of this. - OPPILATION, in Medicine, the act of obstructing or stop- ping up the ducts or passages of the body by redundant or peccant humours. OPPOSITION, in Astronomy, is that aspect of any two heavenly bodies, when they are diametrically opposite each other, or 180°, that is, a semicircle, apart. OPTICS, the science of vision, including Catoptrics and Dioptrics, and even Perspective ; as also the whole doctrine of light and colours, and all the phenomena of visible objects. See PERSPECTIVE. - - By a ray of light, is meant the motion of a single particle; and its motion is represented by a straight line. Any parcel of rays proceeding from a point, is called a pencil of rays. By a medium, is meant any pellucid or transparent body, which suffers light to pass through it. Thus, water, air, and glass, are called media. Parallel rays, are such as move always at the same distance from each other. If rays continually recede from each other, they are said to diverge. If they continually approach towards each other, they are said to converge, The point at which converging rays meet is called the focus. The point towards, which they tend, but which they are prevented from coming to by some obstacle, is called the imaginary focus. When rays, after passing through one medium, on entering another medium of different density, are bent out of their former course, and made to change their direction, they are, said to be refracted. When they strike against a surface, and are sent back again from the surface, they are said to be re- flected. A lens, is glass ground into such a form as to collect or disperse the rays of light which pass through it. These are of different shapes, and from thence receive different names. A plano convex is one side flat, and the other convex. A plano concave is flat on one side, and concave on the other. A double convex, is convex on both sides. A double concave, is concave on both sides. A meniscus, is convex on one side and concave on the other. A line passing through the centre of a lens, is called its axis. Of Refraction.—If the rays of light, after passing through a medium, enter another of a different density perpendicular to its surface, they proceed through this medium in the same direc- tion as before. But if they enter obliquely to the surface of a medium, either denser or rarer than what they moved in before, they are made to change their direction in passing through that medium. If the medium which they enter be denser, they move through it in a direction nearer to the perpendicular drawn to its surface. On the contrary, when light passes out of a denser into a rarer medium, it moves in a direction farther 9 C . 742 O P T O P "T DICTIONARY OF MECHANICAL SCIENCE. from the perpendicular. This refraction is greater or less, that is, the rays are more or less bent or turned aside from tneir course, as the second medium through which they pass is more or less dense than the first. Upon a smooth board, about the centre C, (plate Optics, fig. 4.) describe a circle H O K P; draw two diameters of the circle, OP, H K, perpendicular to each other; draw A D M perpen- dicular to O P; cut off DT and C I equal to three-fourths D A ; through TI, draw TIS, cutting the circumference in S; NS drawn from S perpendicularly upon OP, will be equal to DT, or three-fourths of D.A. Then if pins be stuck perpendicularly at A, C, and S, and the board be dipped in the water as far as the line H K, the pin at S will appear in the same line with the pins at C and C. This shews, that the ray which comes from the pin S is so refracted at C, as to come to the eye along the line C A ; whence the sine of incidence A D is to the sine of refraction NS, as 4 to 3. If other pins were fixed along C.S, they would all appear in A C produced; which shews, that the ray is bent at the surface only. The same may be shewn at different inclinations of the incident ray, by means of a move- able rod turning upon the centre C, which always keeps the ratio of the sines A D, NS, as 4 to 3. Also the sun’s shadow, coinciding with A C, may be shewn to be refracted in the same manner. The image L of a small object S, placed under water, is one-fourth nearer the surface than the object. And hence, the bottom of a pond, river, &c. is one-third deeper than it appears to a spectator. - To prove the refraction of light in a different way, take an upright empty vessel into a dark room; make a small hole in the window shutter, so that a beam of light may fall at the bottom at a, fig. 5, where you may make a mark. Then fill the basin with water, without moving it out of its place, and you will see that the ray, instead of falling upon a will fall upon b. If a piece of looking-glass be laid in the bottom of the vessel, the light will be reflected from it, and will be observed to suffer the same refraction as in coming in ; only in a contrary direc- tion. If the water be made a little muddy, by putting into it a few drops of milk, and if the room be filled with dust, the rays will be rendered much more visible. Of Reflection.—When a ray of light falls upon any body, it is reflected so that the angle of incidence is equal to the angle of reflection; and this is the fundamental fact upon which all the properties of mirrors depend. Let a ray of light, passing through a small hole into a dark room, be reflected from a plane mirror, at equal distances from the point of reflection, the incident and the reflected ray will be at the same height from the surface. The same is found to hold in all cases when the rays are reflected at a curved surface, whether it be convex or concave. - - The rays which proceed from any remote terrestrial object are nearly parallel at the mirror: not strictly so, but come di- verging to it in several pencils, or, as it were, bundles of rays, from each point of the side of the object next the mirror, there- fore they will not be converged to a point at the distance of half the radius of the mirror's concavity from its reflecting sur- face, but in separate points at a greater distance from the mir- ror. And the nearer the object is to the mirror, the further these points will be from it, and an inverted image of the object will be formed in them, which will seem to hang pendent in the air; and will be seen by an eye placed beyond it (with regard to the mirror,) in all respects like the object, and as distinct as the object itself. If a man place himself directly before a large concave mirror, but further from it than its centre of concavity, he will see an inverted image of himself in the air, between him and the mir- ror, of a less size than himself. And if he hold out his hand toward the mirror, the hand of the image will come out towards his hand, and coincide with it, of an equal bulk, when his hand is in the centre of concavity, and he will imagine he may shake hands with his image. If he reach his hand further, the hand of the image will pass by his hand, and come between it and his body ; and if he move his hand toward either side, the hand of the image will move towards the other : so that what- ever way the object moves, the image will move the contrary way. A by stander will see nothing of the image, because none of the reflected rays that form it enter his eyes. The images formed by convex specula are in positions simi- lar to those of their objects; and those also formed by concave specula, when the object is between the surface and the princi- pal focus; in these cases the image is only imaginary, as the reflected rays never come to the foci from whence they seem to diverge. In all other cases of reflection from concave spe- cula, the images are in positions contrary to those of their ob- jects, and these images are real, for the rays after reflection do come to their respective foci. - Colours.--The origin of colours is owing to the composition which takes place in the rays of light, each heterogeneous ray consisting of innumerable rays of different colours; this is evi- dent from the separation that ensues in the well-known expe- riment of the prism. A ray being let into a darkened room, through a small round aperture, and falling on a triangular glass prism, is, by the refraction of the prism, considerably di- lated, and will exhibit on the opposite wall an oblong image, called a spectrum, variously coloured, the extremities of which are bounded by semi-circles, and the sides are rectilinear. The colours are commonly divided into seven, which, however, have various shades gradually intermixing at their juncture. Their order, beginning from the side of the refracting angle of the prism, is red, orange, yellow, green, blue, purple, violet. The obvious conclusion from this experiment is, that the seve- ral component parts of solar light have different degrees of refrangibility, and that each subsequent ray in the order above mentioned is more refrangible than the preceding. As a cir- cular image would be depicted by the solar ray unrefracted by the prism, so each ray that suffers no dilatation by the prism would mark out a circular image. Hence it appears that the spectrum is composed of innumerable circles of different co- lours. The mixture, therefore, is proportionable to the num- ber of circles mixed together, but all such circles are mixed to- gether, whose centres lie between those of two contingent cir- cles, consequently the mixture is proportionable to the interval of those centres, i. e. to the breadth of the spectrum. If, there- fore, the breadth can be diminished, retaining the length of the rectilinear sides, the mixture will be lessened proportionably, and this is done by the following process. . . At a considerable distance from the hole 2, place a double convex lens, fig. 6, whose focal length is equal to half that dis- tance, and place the prism ac, behind the lens; at a distance behind the lens, equal to the distance of the lens from the hole, will be formed a spectrum, the length of whose rectilinear sides is the same as before, but its breadth much less ; for the undi- minished breadth was equal to a line subtending, at the dis- tance of the spectrum from the hole, an angle equal to the ap- parent diameter of the sun, together with a line equal to the diameter of the hole; but the reduced breadth is equal to the diameter of the hole only ; the image of the hole formed by the lens at the distance of double its focal length, is equal to the hole; therefore, its several images in the different kinds of rays are equal to the same, i. e. the breadth of the reduced spectrum is equal to the diameter of the hole. - A prism placed in an horizontal position would project the ray into an oblong form ; apply another horizontal prism simi- lar to the former, to receive the refracted light emerging from the first, and having its refracted angle turned the contrary way from that of the former. The light, after passing through both prisms, will assume a circular form, as if it had not been at all refracted. If the light emerging from the first prism be received by a second, whose axis is perpendicular to that of the former, it will be refracted by this transverse prism into a position inclined to the former, the red extremity being least and the violet most removed from its former position; but it will not be at all altered in breadth. Close to the prism A, fig. 7, place a perforated board a b, and let the refracted light, having passed through the small hole, be received on a second board cd, parallel to the first, and perfo- rated in like manner ; behind that hole in the second board place a prism, with its refracting angle downward; turn the first prism slowly about its axis, and the light will move up and down the second board; let the colours be transmitted succes- sively, and mark the places of the different coloured rays on the wall after their refraction by the second prism, the red will appear lowest, the violet highest, the rest in the intermediate %. 2 ºz-Z/? º- N M L F H = | | º : ". º Nº ºt S sºs s | | sº | | | - º | | ////e or ºpowº Mºos”. - ºo/* Mºscºpe. * * - Fºr sºn & -----n - M- o P Tº O P ‘I' 743 DICTIONARY OF MECHANICAL SCIENCE. places in order. Here then the light being very much simplified, and the incidences of all the rays on the second prism exactly the same ; the red was least refracted, the violet most, &c. The permanency of these original colours appears from hence, that they suffer no manner of change by any number of refrac- tions, as is evident from the last mentioned experiment; nor yet by reflection, for if any coloured body be placed in simpli- fied homogeneous light, it will always appear of the same colour as the light in which it is placed, whether that differ from the colour of the body or not; e.g. if ultramarine and vermilion be placed in red light, both will appear red; in a green light, green; in a blue light, blue, &c. It is however to be allowed, that a body appears brighter when in a light of its own colour than in another; and from this we see that the colours of natu- ral bodies arise from an aptitude in them to reflect some rays more copiously and strongly than others; but lest this pheno- menon should produce a doubt of the constancy of the primary colours, it is proper to assign the reason of it, which is this; that when placed in its own coloured light, the body reflects the rays of the predominant colour more strongly than any of those intermixed with it; therefore the proportion of the rays of the predominant colour to those of the others, in the reflected light, will be greater than in the incident light; but when the body is placed in a light of a different colour from its own, for a similar reason the contrary effect will follow, i. e. the propor- tion of the predominant colour to the others would be less in the reflected than in the incident light, and therefore as its splendour would be greater in the former case, and would be less in the latter, than if all the rays were effectually reflected, the splendour of the predominant colour will be much greater in the former case than in the latter. White is compounded of all the primary colours mixed in their due proportions, for if a solar ray be separated by the prism into its component, and at a proper distance a lens be so placed as to collect the di- verging coloured rays again into a focus, a paper placed per- pendicularly to the rays in this point will exhibit whiteness. The same conclusion may be drawn from the experiment of mixing together paints of the same colour as the parts of the spectrum, and in the same proportion ; the mixture will be white, though not of a resplendent whiteness, because the co- lours mixed are less bright than the primary ones; this may likewise be proved, by fixing pieces of cloth of all the seven different colours on the rim of a wheel, and whirling it round with great velocity, it will appear to be white. Though seven different colours are distinguishable in the prismatic spectrum, yet upon examining the matter with more accuracy, we shall see that there are, in fact, only three original colours, red, blue, and yellow ; for the orange being situated between the red and yellow, is only the mixture of these two; the green in like man- ner arises from the blue and yellow ; and the violet from the blue and red. As the colour of a body therefore proceeds from a certain combination of the primary rays which it reflects; the combination of rays flowing from any point of an object will, when connected by a glass, exhibit the same compound colour in the corresponding point of the image. Hence appears the reason why the images formed by glasses have the colours of the object which they represent. . Vision.—Objects presented to the eye have their images painted on the back part of the retina, the rays of the incident pencils converging to their proper foci there by the refraction of the different humours; and for this office they are admirably adapted ; for as the distance between the back and front of the eye is very small, and the rays of each of the pencils that form the image fall parallel, or else diverging on the eye, a strong refractive power is necessary for bringing them to their foci at the retina; but each of the humours, by its peculiar form and density, contributes to cause a convergence of the rays; the aqueous from its convex form ; the crystalline by its double convexity and greater density than the aqueous; and the vitre- ous by a less density than the crystalline joined to its concave form. The structure of the eyes is in general adapted to the reception of parallel rays, but as the distances of visible objects are various, so the eye has powers of accommodating itself to rays proceeding from different distances by altering the dis- tances of the crystalline from the retina, which is done by the action of the ciliary ligaments. - Defective sight arises from an incapacity of altering the position of the crystalline within the usual limits. 1. When it cannot be brought close enough to the cornea, near objects ap- pear indistinct; to this defect people in years are generally subject. , 2. Where the crystalline cannot be drawn sufficiently near to the retina, remote objects appear indistinct; this is the defect under which short-sighted people labour. In each of these cases the images of the different points in the object would be diffused over small circles on the retina: and so being intermixed and confounded with each other, would there form a very confused picture of the object: for in the former case, fig. 8, the image of any point would be formed behind the retina, as the refraction of the eye is not sufficiently strong to bring the rays (diverging so much as they do in proceeding from a near point) to a focus at the retina. This defect wift therefore be remedied by a convex glass a b, fig. 8, which makes the point whence the rays now proceed more distant than the object; therefore the rays falling on the eye will now diverge less than before, or else be parallel, and will of course be brought to a nearer focus, viz. at the retina. - In the latter case, the image is formed before the retina, fig. 9, because the refractive power of the eye is too great to permit rays so little diverging (as they do in proceeding from a distant point) to reach the retina before they are collected into a focus: in this case, the defect is supplied by a concave glass, which makes the point whence the rays diverge, nearer than the object; consequently, the rays falling on the eye will now diverge more than before, so as when refracted through the humours not to come to their focus before they reach the retina. Therefore spectacles are constructed concave for short-sighted, and convex for long-sighted people. And the frames of spectacles should be so bent, that the axes of both glasses may be directed to one point, at such a distance as you generally look with spectacles; by this means the eyes will fall perpendicularly upon both glasses, and make the object appear distinct; whereas if they fall obliquely upon the glasses the object will appear confused and indistinct. Optical Instruments.--The impediments to the vision of very near objects arise from too great a divergence of the rays in each pencil incident on the eye, and are remedied by the microscope. A - Microscopes.—The most powerful single microseopes are very small globules of glass, which any curious person may make for himself by melting the ends of fine threads of glass in the flame of a candle; or by taking a little fine powdered glass on the point of a very small needle, and melting it into a globule in that way. It was with such microscopes as these that Lewenhoek made all his wonderful discoveries, most of which are deposited in the British Museum. The Double or Compound Microscope differs from the pre- ceding in this respect, that it consists of at least two lenses, by one of which an image is formed within the tube of the microscope; and this image is viewed through the eye-glass, instead of the object itself, as in the single microscope. In this respect the principle is analogous to that of the telescope, only that, as the latter is intended to view distant objects, the object-lens is of a long focus, and consequently of a moderate. magnifying power, and the eye-glass of a short focus, which magnifies considerably the image made by the object lens. Whereas the microscope being intended only for minute objects, the object-lens is consequently of a short focus, and the eye-glass in this case is not of so high a magnifying power. We have explained this instrument under Microscope. The Solar Microscope is a kind of camera obscura, which, in a darkened chamber, throws the image on a wall or screen. It consists of two lenses fixed opposite a hole in a board or windowshutter; one, which condenses the light of the sun upon the object, (which is placed between them,) and the other, which forms the image. There is also a plain reflector placed without, moved by a wheel and pinion, which may be so regulated as to throw the sun’s rays upon the outer lens. Mr. Adam’s most ingenious invention, the lucernal microscope, is also to be considered as a kind of camera obscura; only the light in this latter case proceeds from a lamp, instead of from the sun, which renders it convenient to be used at all times. But for a description of this elegant and most amusing 744 O. P. T. , o P T DICTIONARY OF MECHANICAL scIENCE. instrument, we must refer to his Microscopical Essay. See MicroscoPE. - . . . . Telescopes.—From what has been said on the nature of the compound microscope, the principle of the telescope may be easily understood. Telescopes are, however, of two kinds ; the one depending on the principle of refraction, and called the dioptric telescope; the other, on the principle of reflection, and therefore termed the reflecting telescope. . The parts essential to a dioptric telescope are, the two lenses AD and EY, fig. 10. As in the compound microscope, A D is the object-glass, and EY is the eye-glass; and these glasses are so combined in the tube, that the focus F of the one is exactly coincident with the focus of the other. , Let Q B then represent a very distant object, from every point of which pen- cifs of rays will proceed, so little diverging to the object lens AD, that they may be considered as nearly parallel; I M will then be the image which would be formed on a screen by the action of the lens A. D. For supposing O A and B D two pen- cils of rays proceeding from the extreme points of the object, they will unite in the focal point F, and intersect each other, But the point F is also the focus of the eye-glass EY; and therefore the pencil of rays, instead of going on to diverge, will pass through it in nearly a parallel direction, so as to cause distinct vision. It is then plain, that as in the compound microscope, it is the image which is here contemplated ; and this will account for the common sensation when people say the object is brought nearer by a telescope. For the rays, which after crossing proceed in a divergent state, fall upon the lens EY, as if they proceeded from a real object situated at F. All that is effected by a telescope then, is to form such an image of a distinct object, by means of the object lens, and then to give the eye such assistance as is necessary for viewing that image as near as possible, so that the angle it shall sub- tend at the eye shall be very large compared with the angle which the object itself would subtend in the same situation. This is effected by means of the eye-glass, which refracts the pencils of rays, so that they may be brought to their several foci by the humours of the eye, as has been described. To ex- plain clearly, however, the reason why it appears magnifica, we must again have recourse to the figure. O B being at a great distance, the length of the telescope is inconsiderable with respect to it. Supposing, therefore, the eye viewed it from the centre of the object-glass C, it would see it under the angle O C.B.; let O C and B C then be produced to the focus of the glass, they will then limit the image IM formed in the focus. If then two parallel rays are supposed to proceed to the eye-glass E Y, they will be converged to its focus H ; and the eye will see the image under the angle E. H. Y. The appa- rent magnitude of the object seen by the naked eye, is, there- fore, to that of the image which is seen through the telescope, as the magnitude of the angle O C B, or IC M, to that of E HY, or I G. M. Now, the angle I G M is to I C M as C F to F. G.; that is, as the focal length of the object-glass to that of the eye-glass.-The magnifying power of these glasses may be augmented to a considerable degree, because the focal length of the object-glass, with respect to that of the eye-glass, may be greatly increased. This, however, would require a tube of immense length; because an eye-glass of a very short focus would cause such a dispersion of the rays of light, particularly towards the edges of the glass, that the view would be inter- cepted by the prismatic colours. Another manifest defect in these telescopes is, that the image appears inverted ; this, however, is of no consequence with respect to the heavenly bodies; and on this account it is still used as an astronomical telescope. One of almost a similar construction is also used on board of ships as a night glass, to discover rocks in the ocean, or an enemy’s fleet. Notwithstanding the inconvenience of exhibiting the objects inverted, more glasses than two can- not be employed from the paucity of light; and habit soon enables the persons who use them to discern objects with tolerable distinctness. The brightness of the appearance through any of these telescopes or microscopes, depends chiefly on the aperture of the object-glass. For if the whole of that glass was covered, except a small aperture in the middle, the magnitude of the image would not be altered; but fewer rays of every pencil being admitted, the object would appear ob- | scure. In a few words, the apparent distinctness or confusion, of any object, viewed through glasses, depends on the mutual. inclination of the rays in any one pencil to each other, when, they fall on the eye; the apparent magnitude depends upon the inclination of the rays of different pencils to each other; the apparent situation depends upon the real situation of the extreme pencils; and the apparent brightness or obscurity . depends on the quantity of rays in each pencil. - The well-known property in concave speculums, of causing the pencils of rays to converge to their foci, and there forming an image of any object that may be opposed to them, gave rise to the reflecting telescope. In this, the effect is precisely the same as that produced by the dioptric telescope; only that in the one case it is produced by reflected, and in the other by refracted light. Reflecting telescopes are made in | various forms ; and those principally in use in this country are distinguished by the names of their respective inventors, and are called the Newtonian, Gregorian, and Herschelian tele-. scopes. The reflecting telescopes on the Gregorian principle, which is the most common, as it is found to be the most con- venient, is constructed in the following manner:—At the bottom of the great tube, fig. 11, TTTT, is placed a large con- cave mirror D U V F, whose principal focus is at m; and in the middle of this mirror is a round hole P, opposite to which is placed the small mirror II, concave toward the great one, . and so fixed to a strong wire M, that it may be removed fur- ther from the great mirror, or nearer to it, by means of a long screw in the inside of the tube, keeping its axis still in the same line P m n with that of the great one. Now, since in viewing a very remote object, we can scarcely see a point of it but what is, at least, as broad as the great mirror, we may consider the rays of each pencil, which flow from every point of the object, to be paral- lel to each other, and to cover the whole reflecting surface D U VF. But to avoid confusion in the figure, we shall only draw two rays of a pencil flowing from each extremity of the object into the great tube, and trace their progress through all their reſlec- tions and refractions to the eye f at the end of the small tube t t, which is joined to the great one. Let us then suppose the object A B to be at such distance, that the rays C may flow from its upper extremity A, and the rays E from its lower extremity B; then the rays C falling parallel upon the great mirror at D, will be thence reſlected, converging in the direc- tion D G ; and by crossing at I in the principal focus in the mirror, they will form the lower extremity of the inverted image IK, similar to the upper extremity A of the object AB; and passing on to the concave mirror L, (whose focus is at n,) they will fall upon it at g, and be thence reflected, converging in the direction g N, because g m is longer than g n; and pass- ing through the hole P in the large mirror, they would meet somewhere about 1", and form the upper extremity a of the erect image a b, similar to the upper extremity A of the object A. B. But by passing through the plano-convex glass R, in their way, they form that extremity of the image at a. In the same manner the rays E, which come from the bottom of the object A B, and fall parallel upon the great mirror at F, are thence reflected, converging to its focus; where they form the upper extremity I of the inverted image IK, similar to the lower extremity B of the object AB; and thence passing on the small mirror L, and falling upon it at h, they are hence reflected in the converging state h O; and going on through the hole P of the great mirror, they would meet somewhere about q, and form there the lower extremity b of the erect image a b, . similar to the lower extremity B of the object A B; but by . passing through the convex glass R in their way, they meet and cross sooner, as at b, where the point of the erect image is formed. The like being understood of all those rays which flow from the intermediate points of the object between A and B, and enter the tube TT, all the intermediate points of the . image between a and b will be formed ; and the rays passing on from the image through the eye-glass S, and through a small hole e in the end of the lesser tube t t, they enter the eye f, which sees the image a b (by means of the eye-glass) under the large angle c e d, and magnified in length under that angle from c to d. . In the best reflecting telescopes the focus of the small mirror is never coincident with the focus m of the great one, where : O P T O P. T. DICTIONARY OF MECHANICAL SCIENCE. 745 the first image IK is formed, but a little beyond it, (with respect to the eye) as at n ; the consequence of which is, that the rays of the pencils will not be parallel after reflection from the small mirror, but converge so as to meet in points about q, e, r ; where they would form a larger upright image than ab, if the glass R was not in their way, and this image might be viewed by means of a single eye-glass properly placed between the image and the eye; but then the field of view would be less, and consequently not so pleasant; for that reason the glass R is still retained, to enlarge the scope or area of the field. - To find the magnifying power of this telescope, multiply the focal distance of the great mirror by the distance of the small mirror from the image next the eye, and multiply the focal dis- tance of the small mirror by the focal distanceof the eye-glass; then divide the product of the former multiplication by that of the latter, and the quotient will express the magnifying power. The difference between the Newtonian and Gregorian tele- scope is, that in the former the spectator looks in at the side through an aperture upon a plane mirror, by which the rays reflected from the concave mirror are reflected to the eye-glass; whereas, in the latter, the reader will see that he looks through the common eye-glass, which is in general more convenient. The immensely powerful telescopes of Dr. Herschel are of a still different construction. This assiduous astronomer made several specula, which were of an immense magnifying power on distant objects. The object is reflected by a mirror, as in the Gregorian telescope, and the rays are intercepted by a lens at a proper distance, so that the observer has his back to the object, and looks through the lens at the mirror. The magni- fying power will, in this case, be the same as in the Newtonian telescope; but there not being a second reflector, the bright- ness of the object viewed in the Herschelian is greater than that in the Newtonian or Gregorian telescope. In conclusion, Sir Isaac Newton's excellent maxim must not be omitted : “The art,” says he, “of constructing good microscopes and telescopes, may be said to depend on the circumstance of making the last image as large and distinct and luminous as possible.” See Telescope. Of the Rainbow, and other remarkable Optical Phenomena.- Since the rays of light are found to be decompounded by refracting surfaces, we can no longer be surprised at the changes produced in any object by the intervention of another. The vivid colours which gild the rising or the setting sun, must necessarily differ from those which adorn its noon-day splen- dour. There must be the greatest variety which the liveliest fancy can imagine. The clouds will assume the most fantastic forms, or will lower with the darkest hues, according to the different rays which are reflected to our eyes, or the quantity absorbed by the vapours in the air. The ignorant multitude will necessarily be alarmed by the sights in the heavens; by the appearance at one time of three, at another of five, suns; or circles of various magnitudes round the sun or moon; and thence conceive that some fatal change in the physical or the moral world, some fall of empires, or tremendous earth- quake ; while the optician contemplates them merely as the natural and beautiful effects produced by clouds or vapour, in various masses, upon the rays of light. One of the most beau- tiful and common of these appearances deserves particular investigation, as, when this subject is well understood, there will be little difficulty in accounting for others of a similar nature, dependent on the different refrangibility of the rays of light. Frequently, when our backs are turned to the sun, and there is a shower either around us, or at some distance before us, a bow is seen in the air, adorned with all or some of the seven primary colours. The appearance of this bow,which in poetical language is called the iris, and in common language the rainbow, was an inexplicable mystery to the ancients; and, though now well understood, continues to be the subject of admiration to the peasant and the philosopher. We are indebted to Sir Isaac Newton for the explanation of this appearance ; and by various easy experiments, we may convince any man that his theory is founded on truth. If a glass globe is suspended in the strong light of the sun, it will be found to reflect the different prismatic colours exactly in proportion to the position in which it is placed; in other 76. words, agreeably to the angle which it forms with the specta- tor's eye, and the incidence of the rays of light. The fact is, that innumerable pencils of light fall upon the surface of the globe, and each of these is separated as by a prism. To make this matter still clearer, let us suppose the circle B A W, fig. 12, to represent the globe, or a drop of rain, for each drop may be considered as a small globe of water. The red rays, it is well known, are least refrangible; they will therefore be refracted, agreeably to their angle of incidence, to a certain point A in the most distant part of the globe; the yellow, the green, the blue, and the purple rays, will each be refracted to another point. A part of the light, as refracted, will be trans- mitted, but a part will also be reflected ; the red rays at the point A, and the others at certain other points, agreeably to their angle of refraction. It is very evident, that if the spec- tator's eye is placed in the direction of M W, or the course of the red-making rays, he will only distinguish the red colour; if in another situation, he will see only by the yellow rays; in another, by the blue, &c.; but, as in a shower of rain there are drops at all heights and all distances, all those that are in a certain position with respect to the spectator, will reflect the red rays, all those in the next station the orange, those-in the next the green, &c. To avoid confusion, let us for the present imagine only three drops of rain, and three degrees of colours . in the section of the bow, fig. 13. It is evident, that the angle . C E P is less than the angle B E P, and that the angle A EP is the greatest of the three. This largest angle then is formed by the red rays, the middle one consists of the green, and the smallest is the purple. All the drops of rain, therefore, that happen to be in a certain position to the eye of a spectator, will reflect the red rays, and form a band or semicircle of red; those again in a certain position will present a band of green, &c. If he alters his station, the spectator will see a bow, though not the same bow as before : and if there are many spectators, they will each see a different bow, though it appears to be the same. There are sometimes seen two bows, one formed as has been described, the other appearing externally to embrace the primary bow, and which is sometimes called the secondary or false bow, because it is fainter than the other, and what is most remarkable is, that in the false bow the order of the colours appears always reversed. In the true or primary bow we have seen that the rays of light arrive at the spectator's eye after two refractions and one reflection; in the secondary bow the rays are sent to our eyes after two refractions and two reflections, and the order of the colours is reversed, because in this latter case the light enters at the inferior part of the drop, and is transmitted through the superior. Thus, fig. 12, the ray of light which enters at B, is refracted to A, whence it is re- flected to P, and again reflected to W, where, suffering another refraction, it is sent to the eye of the spectator. The colours of this outer bow are fainter than those of the other, because the drop being transparent, a part of the light is transmitted, and consequently lost at each reflection. The phenomenon assumes a semicircular appearance, be- cause it is only at certain angles that the refracted rays are visible to our eyes. The least refrangible, or red rays, make an angle of 42 degrees two minutes, and the most refrangible or violet rays an angle of 40 degrees 17 minutes. Now, if a line be drawn horizontally from the spectator's eye, it is evident, that angles formed with this line, of a certain dimension in every direction, will produce a circle; as will be evident, by only attaching a cord of a given length to a certain point, round which it may turn as round its axis, and in every point will describe an angle with the horizontal line of a certain and determinate extent. Let H O, for instance, fig. 14, represent the horizon, BW a drop of rain at any altitude, S B a line drawn from the sun to the drop, which will be parallel to a line S M drawn from the eye of the spectator to the sun. The course of part of the decompounded ray S B may be first by refraction from B to A, then by reflection from A to W ; lastly, by refraction from W to M. Now, all drops, which are in such a situation that the incident and emergent rays S B, MW, produced through them, make the same angle SN M, will be the means of exciting in the spectaters the same idea of colour. Let M W turn upon H O as an axis, till W meets the horizon 9 D -* 746 O P T O P T DICTIONARY OF MIECHANICAL SCIENCE, on both sides, and the point W will describe the arc of a circle; , and all the drops placed in its circumference will have the property we have mentioned, of transmitting to the eye a particular colour. When the plane H M W A is perpendicu- lar to the horizon, the line M W is directed to the vertex of the bow, and W K is its altitude. This altitude depends on two things, the angle between the incident and emergent rays, and the height of the sun above the horizon ; for since S M is parallel to SN, the angle S N M is equal to N M I; but S M H, the altitude of the sun, is equal to K M I; therefore the alti- tude of the bow W M K, which is equal to the difference between W M I and K M I, is equal to the difference be tween the angles made by the incident and emergent rays and the altitude of the sun. The angle between the incident and emergent rays is different for the different colours, as was already intimated ; for the red, or least refrangible, rays, it is equal to 42 degrees 2 minutes; for the violet or most refrangi- ble, it is equal to 40 degrees 17 minutes; consequently, when the sun is more than 42 degrees 2 minutes above the horizon, the red colour cannot be seen ; when it is above 40 degrees 17 minutes, the violet colour cannot be seen. The secondary bow is made in a similar manner; but the sun's rays suffer, in this case, two reflections within the drop. The ray S B, fig. 14, is decompounded at B; and one part is refracted to A, thence reflected to P, and from P reflected to W, where it is refracted to M. The angle between the incident and emergent rays S N M is equal as before to N M I; and N M K, the height of the bow, is equal to the difference between the angle made by the incident and emergent rays and the height of the sun. In this case the angle S N M, for the red rays, is equal to 50 de- grees 7 minutes, and for the violet rays it is equal to 54 de- grees 7 minutes, consequently the upper part of the secondary bow will not be seen when the sun is above 54 degrees 7 min. above the horizon, and the lower part of the bow will not be seen when the sun is 50 degrees 7 minutes above the horizon. In the same manner innumerable bows might be formed by a greater number of reflections within the drops; but as the secondary is so much fainter than the primary, that all the colours in it are seldom seen ; for the same reason a bow made with three reflections would be fainter still, and in general altogether imperceptible. Since the rays of light, by various reflections and refractions, are thus capable of forming, by Ineans of drops of rain, the bows which we so frequently see in the heavens, it is evident that there will be not only solar and lunar bows, but that many striking appearances will be produced by drops upon the ground or air, on the agitated surface of the water. Thus a lunar bow will be formed by rays from the moon affected by drops of rain ; but as its light is very faint in comparison with that of the sun, such a bow will very seldom be seen, and the colours of it when seen will be faint and dim. - % - The marine or sea bow is a phenomenon sometimes observed in a much agitated sea; when the wind, sweeping part of the tops of the waves, carries them aloft, so that the sun’s rays, falling upon them, are refracted, &c. as in a common shower, and paint the colours of the bow. Rohault mentions coloured bows on the grass, formed by the refraction of the sun’s rays in the morning dew. Dr. Langwith, indeed, once saw a bow lying on the ground, the colours of which were almost as lively as the common rainbow. It was extended several hundred yards. It was not round, but oblong, being, as he conceived, the portion of an hyperbola. The colours took up less space, and were much more lively, in those parts of the bow which were near him than in those which were at a distance. The drops of rain descend in a globular form, and thence we can easily account for the effects produced by them on the rays of light; but in different states of the air, instead of drops of rain, vapour falls to the earth in different forms of sleet, Snow, and hail. In the two latter states there cannot be a re- fraction of the rays of light; but in the former state, when a drop is partly in a congealed and partly in a fluid form, the rays of light will be differently affected, both from the form of the drop and its various refracting powers. Hence we may expect a variety of curious appearances in the heavens; and to those drops, in different states, we may attribute the for- mation of halos, parhelia, and many other phenomena, detailed in the Philosophical Transactions, or in the histories of every country. - The halo, or corona, is a luminous circle surrounding the sun, the moon, a planet, or a fixed star. It is sometimes quite white, and sometimes coloured like the rainbow. Those which have been observed round the moon or stars are but of a very small diameter; those round the sun are of different magni- tudes, and sometimes immensely great. When coloured, the colours are fainter than those of the rainbow, and appear in a different order, according to their size. In those which Sir Isaac Newton observed in 1692, the order of the colours, from the inside next the sun, was in the innermost blue, white, red; in the middle purple, blue, green, yellow, pale red ; in the outermost pale blue, and pale red. Huygens observed one red next the sun, and pale blue at the extremity. Mr. Weidler has given an account of one yellow on the inside, and white on the outside. In France one was observed, in which the order of the colours was white, red, blue, green, and a bright red on the outside. . . - - Artificial coronas may be made in cold weather, by placing a lighted candle in the midst of a cloud of steam; or if a glass window is breathed upon, and the flame of a candle placed at Some distance from the window, while the operator is also at the distance of some feet from another part of the window, the flame will be surrounded with a coloured halo. : The parhelia, or mock suns, are the most splendid appear- ances of this kind. The parhelia generally appear about the size of the true sun, not quite so bright, though they are said sometimes to rival their parent luminary in splendour. When there are a number of them, they are not equal to each other in brightness. Externally they are tinged with colours like the rainbow. They are not always round, and have sometimes a long fiery tail opposite the sun, but paler towards the extremity. Dr. Haller observed one with tails extending both ways. Mr. Weidler saw a parhelion with one tail pointing up and another downward, a little crooked; the limb which was farthest from the sun being of a purple colour, the other tinged with the colours of the rainbow. . . Coronas generally accompany parhelia: some coloured, and others white. There is also, in general, a very large white cir- cle, parallel to the horizon, which passes through all the par- helia; and if it was entire, would go through the centre of the sun : sometimes there are arches of smaller circles concentric to this, and touching the coloured circles which surround the sun; they are also tinged with colours, and contain other par- helia. One of the most remarkable appearances of this kind was that which was observed at Rome by Scheiner, as inti- mated above; and this may serve as a suſlicient instance of the parhelion. - This celebrated phenomenon is represented in fig. 15, in which A is the place of the observer, B his zenith, C the true sun, and A B a plane passing through the observer's eye, the true sun, and the zenith. About the sun C there appeared two concentric rings, not complete, but diversified with colours. The lesser of them D E F, was fuller and more perfect; and though it was open from D to F, yet, those ends were per- petually endeavouring to unite, and sometimes they did so. The outer of these rings was much fainter, so as scarcely to be discernible. It had, however, a variety of colours, but was very inconstant. The third circle, KL MN, was very large, and entirely white, passing through the middle of the sun, and every where parallel to the horizon. At first this circle was entire ; but towards the end of the phenomenon it was weak and ragged, so as hardly to be perceived from M towards N. In the intersection of this circle and the outward iris G. K.I, there broke out two parhelia, or mock suns, N and K, not quite per- fect, K being rather weak, but N shone brighter and stronger. The brightness of the middle of them was something like that of the sun; but towards the edges they were tinged with colours like those of the rainbow, and were uneven and ragged. The parhelion N was a little wavering : and sent out a spiked tail NP, of a colour somewhat fiery, the length of which was continually changing. The parhelia at L and M, in the hori- zontal ring, were not so bright as the former, but were rounder, and white, like the circle in which they were placed. The par- helion N disappeared before K; and while M grew fainter, K O P T O P T 747 DICTIONARY OF MECHANICAL SCIENCE. grew brighter, and vanished the last of all. It is to be observed farther, that the order of the colours in the circles DE F, G KN, was the same as in the common halos, namely, red next the sun; and the diameter of the inner circle was also about 45 deg., which is the usual size of a halo. Parhelia have been seen...for one, two, three, and four hours together; and in North America they are said to continue some days, and to be visible from sun-rise to sun-set. When they disappear it some- times rains, or snow falls in the form of oblong spiculae. At Churchill, in Hudson’s Bay, the rising of the sun is always preceded by two long streams of red light, which rise as the sun rises; and as they grow longer, begin to bend towards each other, till they meet directly over the sun, forming there a kind of parhelion or mock sun. These two streams of light seem to have their source in two other parhelia, which rise with the true sun; and in the winter season, when the sun never rises above the haze or fog which is constantly found near the horizon, all these accompany him the whole day, and set with him in the same manner as they rise. A fourth par- helion may sometimes be seen under the true sun ; but this is not common. The cause of these is apparently the reflection of the sun's light and image from the thiók and frozen clouds in the northern atmosphere, accompanied also with some degree of refraction. To enter upon a mathematical analysis of these phenomena would be only tedious, and very foreign to our pur- pose. From what has been said upon this subject, it is evi- dent that all the phenomena of colours depend upon two pro- perties of light, the refrangibility and reflexibility of its rays. Of the Inflection of Light.—The direction of the rays of light is changed, as we have seen, in their approach to certain bodies by reflection and refraction; and consequently we must admit that there is some power in these bodies by which such effects are universally produced. If reflection was produced simply by the impinging of particles of light on hard or elastic bodies, or if they were in themselves elastic, the same effects would follow as in the impulse of other elastic bodies; but the angle of incidence could not be equal to the angle of reflection, unless the particles of light were perfectly elastic, or the bodies on which they impinged were perfectly elastic. Now we know that the bodies on which these particles impinge are not per- fectly elastic; and also that if the particles of light were per- fectly elastic, the diffusion of light from the reſlecting bodies would be very different from its present appearance: for as no body can be perfectly polished, the particles of light, which are so inconceivably small, would be reflected back by the in- equalities on the surface in every direction; consequently we are led to this conclusion, that the reflecting bodies are pos- sessed of a power which acts at some little distance from their surfaces. - . If this reasoning is allowed to be just, it necessarily follows, that if a ray of light, instead of impinging on a body, should pass so near to it as to be within the sphere of that power which the body possesses, it must necessarily suffer a change in its direction. Actual experiments confirm the truth of this position ; and to the change in the direction of a particle of light, owing to its nearness to a body, we give the name of inflection. - . From one of these experiments, made by Sir Isaac Newton, the whole of this subject will be easily understood. At the distance of two or three feet from the window of a darkened room, in which was a hole three-fourths of an inch broad to admit the light, he placed a black sheet of pasteboard, having in the middle a hole about a quarter of an inch square, and behind the hole the blade of a sharp knife, to intercept a small part of the light which would otherwise have passed through the hole. The planes of the pasteboard and blade were parallel to each other; and when the pasteboard was removed at such a distance from the window, as that all the light coming into the room must pass through the hole in the pasteboard, he re- ceived what came through this hole on a piece of paper two or three feet beyond the knife, and perceived two streams of faint light shooting out both ways from the beam of light into the shadow. As the brightness of the direct rays obscured the fainter light, by making a hole in his paper he let them pass through, and had thus an opportunity of attending closely to the two streams, which were nearly equal in length, breadth, and quantity of light. That part which was nearest to the sun's direct light was pretty strong for the space of about a quarter of an inch, decreasing gradually till it became imper- ceptible; and at the edge of the knife it subtended an angle of about twelve, or, at most fourteen degrees. Another knife was then placed opposite to the former, and he observed, that when the distance of their edges was about the four-hundredth part of an inch, the stream divided in the middle, and left a shadow between the two parts, which was so dark, that all light passing between the knives seemed to be bent aside to, one knife or the other; as the knives were brought nearer to each other, this shadow grew broader, till upon the contact of the knives the whole light disappeared. - Pursuing his observations upon this appearance, he per- ceived fringes, as they may be termed, of different-coloured light, three made on one side by the edge of one knife, and three on the other side by the edge of the other: and thence concluded, that as in refraction the rays of light are differently acted upon, so are they at a distance from bodies by inflection; and by many other experiments of the same kind he supported his position, which is confirmed by all subsequent experiments. We may naturally conclude, that from this property of inflec- tion some curious changes will be produced in the appearance of external objects. If we take a piece of wire of a less dia- meter than the pupil of the eye, and place it between the eye and a distant object, the latter will appear magnified, (fig. 16.) Let A be a church-steeple, B the eye, C the wire. The rays by which the steeple would have been otherwise seen are in- tercepted by the wire; and it is now seen by inflected rays, which make a greater angle than the direct rays, and conse- quently the steeple will be magnified. - Optical Wonder.—Mr. Scoresby’s Journal of a Voyage to the Northern Whale Fishery, recently published, contains much information respecting the refractions which are usual in high latitudes: one very singular instance deserves to be noticed. “On my return to the ship, about eleven o’clock, the night was beautifully fine, and the air quite mild. The atmosphere, in consequence of its warmth, being in a highly refractive state, a great many curious appearances were presented by the land and ice-bergs. The most extraordinary effect of this state of the atmosphere, however, was the distinct inverted image of a ship in the clear sky, over the middle of the large bay or inlet before mentioned ; the ship itself being entirely beyond the horizon. Appearances of this kind I have before noticed, but the peculiarities of this were—the perfection of the image, and the great distance of the vessel that it represented. It was so extremely well defined, that when examined with a telescope by Dolland, I could distinguish every sail, the general ‘rig of the ship,” and its particular character: insomuch, that I coil- fidently pronounced it to be my father's ship, the Fame, which it afterwards proved to be; though, on comparing notes with my father, I found that our relative position at the time, gave our distance from one another very nearly thirty miles beyond the horizon, and some leagues beyond the limit of direct vision. I was so struck by the peculiarity of the circumstance, that I mentioned it to the officer of the watch, stating my full con- viction that the Fame was then cruising in the neighbouring inlet.” - - In nearly shutting the eyes and looking at a candle, there appear rays of light extending from it in various directions, like comets’ tails; for the light, in passing through the eye- lashes, is inflected; and consequently many separate beams will be formed, diverging from the luminous object. The power of bodies to inflect the rays of light passing near to them will produce different effects, according to the nature of the rays acted upon ; consequently a separation will take place in the differently refrangible ray, and those fringes which were taken notice of by Sir Isaac Newton will appear in other objects, which are seen by the means of inflected rays. From consider- ing thus the action of bodies upon light, we come to this gene- ral conclusion, for which we are indebted to our great philo- sopher—that light, as well as all other matter, is acted upon at a distance; and that reflection, refraction, and inflection, are owing to certain general laws in the particles of matter, which are equally necessary for the preservation of the beautiful har- mony in the objects nearest to us, and to produce by their 748 o R B O R. D DICTIONARY OF MECHANICAL SCIENCE. joint action that great law by which the greater bodies in their system are retained in their respective orbits. - Table of Illuminating Power of Candles.—To ascertain the illuminating power of different sorts of candles, first weigh one of each sort to be tried ; light them all at the same instant; and after the lapse of any given time, say half an hour, extin- guish and again weigh them: compare how much each has lost in weight; that which has lost most, is the sort which affords the strongest light. In order farther to know the comparative expense of burning candles of different kinds, and of various sizes, the reader may consult the following table, which pre- sents the average result of a series of experiments made with a view to the determination of this point:— i '. . | ---. º Expense of burning candles - | W - - º & Description Nº. º #. ; of each description. taking w of wick. dles to candle. one can- pound º," dº."º: ; the lb. al; will I will last. 100th Fº whence may urn. easily be deduced the pro- portional expense, when they are at any other price. oz. Idr. I h. I m. I h. m. Small 5 18 – 14 || 3 || 15 59| 25 8-078 wick & 18 — 13%| 2 | 40|50 | 33 9-475 . 16 – 15%| 2 | 40|| 44 — I 0-909 \ 12 1 5}| 3 || 27| 41 || 32 11-557 Large ) 10 1 | 8 || 3 || 36|| 38 22 I2-5 11 wick 7 2 | 1 || 4 9| 32 12 14-907 8 2 — | 4 || 15||34 || – 14-118 5 2 13 || 5 || 19, 30 12 15.894 Mould Candles, at 12s. per dozen. 5 2 || 12 7 20 || 42 | 40 13°502 4. 4 – 9 3| 36|| 12 15-911 3 5 || 2 || 17 || 30 54 || 4 10.654 Optic Inequality, in Astronomy, is an apparent irregularity in the motions of the planets and other celestial bodies, being thus called, because it does not arise from any real inequality of the moving body, but from the situation of the eye of the observer. Optic Nerves, the second pair of nerves springing from the crura of the medulla oblongata, and passing thence to the eye. OPTIC Place of a planet, is its place as seen by the eye. OPTIC Pyramid, is a pyramid formed by the visual rays pro- ceeding from the eye, and passing through the extremities of any picture, when these rays are continued to terminate in a plane perpendicular to the observer. OPTION, the power or faculty of wishing or choosing, or the choice a person makes of any thing. Hence we say, when a new suffragan bishop is consecrated, the archbishop of the province, by a customary prerogative, claims the collation of the first vacant benefice or dignity in that see; this is the bishop's option. OR, Gold, in Heraldry, denoted by small points all over the field, in engravings of arms; and it is supposed to signify of t itself generosity, splendour, or solidity. ORANGE. See CITRUS. - ORATORIO, a sort of sacred drama, in dialogue, recitative, duettos, trios, ritornellos, and choruses; the subjects being usually taken from scripture, and the music being in the finest taste, and best chosen strains. Lent is the season for per- formances of this description. ORBIS MAGNUs, the great orb in which posed to revolve. ORBIT, the path of any celestial body. The orbits of the several planets were, even after the restoration of the Pytha- gorean System of astronomy by Copernicus, supposed to be 'circular, having the sun in their common centre, which, indeed, was such a rational and simple hypothesis, that it is not at aij singular both Copernicus and Kepler, as well as other astro- nomers of that day, were so unwilling to give up this idea. However, Kepler, after an immense number of observations upon the planet Mars, found that it was impossible to recon- the sun was sup- cile his observations with that theory, and he therefore abandoned it; but now, though he changed the figure from a circle to an ellipse, he still, by supposing the sun in the cen- tre, found nearly the same difficulty in accounting for some of the observed phenomena. At length, however, it happily occurred to him to place the sun in one of the foci, with which position every observed irregularity perfectly agreed; and by that perseverance, for which he is so eminently distinguished, he came finally to those fundamental laws which still bear his name, viz. –1. The planets all revolve in elliptic orbits situ- ated in planes passing through the centre of the sun, the latter body occupying one of the foci of the ellipse. 2. Equal areas are described in equal times. That is, if a line be supposed to join the central and revolving body, that line passes over or describes equal areas in equal times. 3. The squares of the times of revolution in planetary bodies, are as the cubes of their distances from the sun. ORCHARD, a plantation of fruit trees. In planting an orchard great care should be taken that the soil is suitable to the trees planted in it; and that they are procured from a soil nearly of the same kind, ar rather poorer than that laid out for an orchard. As to the situation, an easy rising ground, open to the south-east, is to be preferred. Miller recommends planting the trees fourscore feet asunder, but not in regular rows; and would have the ground between the trees ploughed, and sown with wheat and other crops, in the same manner as if it was clear from trees; by which means the trees will be more vigorous and healthy, will abide much longer, and pro- duce better fruit. If the ground has been pasture, the green- sward should be ploughed in the spring before the trees are planted ; and if it is suffered to lie a summer fallow, it will greatly mend it, provided it is stirred two or three times to rot the grass, and prevent the growing of weeds. At Michaelmas it should be ploughed pretty deep, in order to make it loose for the roots of the trees, which, if the soil is dry, should be planted in October; but if it is moist, the beginning of March will be a better season. If several sorts of fruit trees are to be planted on the same spot, you should observe to plant the largest growing trees backwards, and so proceed to those of less growth, continuing the same method quite through the whole plantation; by which means the sun and air will more easily pass through the whole orchard. When you have planted the trees, you should support them with stakes, to pre- vent their being blown out of the ground by the wind; and the following spring, if the season should prove dry, cut a quantity of green turf, and lay it about the roots, with the grass down- wards; by which means a greater expense of watering will be saved, and after the first year they will be out of danger. Whenever you plough the ground betwixt these trees, you must be careful not to go too deep amongst their roots, which would greatly damage the tree; but if you do it cautiously, your stirring the face of the ground will be of great service to them; though you should observe never to sow too near the tree, nor to suffer any great rooting weeds to grow about'them; because this would starve them, by exhausting the goodness of the soil, which every two or three years should be mended with dung or other manure. These trees, after they are planted out, will require no other pruning besides cutting off their bad branches, or such as cross each other. ORDEAL, a form of trial for discovering innocence or guilt, formerly practised over almost all Europe, and which pre- vailed in England from the time of Edward the Confessor, till it was abolished by a declaration of Henry III. It was called purgatio vulgaris, or judicium, in opposition to bellum, or combat, the other form of purgation. In England, an offender, on being arraigned, and pleading not guilty, had it in his choice to put himself upon God and his country, that is, upon the verdict of the jury; or upon God alone, on which account it was called the judgment of God, it being presumed that God would deliver the innocent. The more popular kinds of ordeal were red-hot iron and water; the first for freemen and people of fashion, and the last for peasants. Fire ordeal was performed either by taking up in the hand a piece of red-hot iron, of one, two, or three pounds weight; or else by walking barefoot and blindfold over nine red-hot ploughshares, laid at unequal distances; and if the party escaped unhurt he was O R. F. O R. G. 749 DICTIONARY OF MECHANICAL SCIENCE. adjudged innocent; if not, he was condemned as guilty, Water ordeal was performed either by plunging the bare arm up to the elbow in boiling water, and escaping unhurt thereby; or by casting the person suspected, into a river or pond of water: if he floated therein, without any action of swimming, it was deemed an evidence of his guilt; but if he sunk, he was acquitted. 4 Black. 340. - ORDER. See ARchitectURE. ORDER of A LINE, in the theory of Curves, denotes the dimension of, the equation by: which the line is expressed; it being of the 1st, 2d, 3d, &c. order, according as the equation is of the 1st, 2d, 3d, &c. degree or dimension. ORDERS, or ORDINATIon. No person shall be admitted to the holy order of deacon under 23 years of age; nor to the order of priest, unless he is. 24 complete; and none shall be ordained without a title, that is, a nomination to some cure or benefice, and he shall have a testimonial of his good behaviour, for three years past, from three clergymen; and the bishop shall examine him, and, if he sees cause, may refuse him. And before he is ordained, he shall take the oath of allegiance and supremacy before the ordinary, and subscribe the thirty-nine articles. ORDINARY, in common and canon law, is one who has an ordinary or immediate jurisdiction in ecclesiastical causes in such a place. ORDINARY Seaman, implies one who can make himself useful on board, but is not an expert.or skilful sailor; the latter being || termed an able seaman. Able seamen have consequently more wages than the ordinary. - Ships in ORDINARY, are those which being laid up are under the direction of the master attendant. ORDINATE, in the theory of Curves. any right line drawn from a point in the absciss to terminate in the or rve . . and i drawn perpendicularly to the absciss, it is called a right ordi- nate. It is a general property of the ordinates of a curve, that when perpendicular to the axis of a line of the second order, that is, in the circle and conic sections, the ordinates are all bisected by that axis, making the sum of all the ordinates on one side equal to that of those on the other; and in lines of the third order, where a line may cut the curve in three places, the ordinate on the one side is always equal to the sum of the ordinates on the other. ORDNANCE, a general name for all sorts of great guns used in war. ORDNANce, Office of, an office kept within the Tower of London, which superintends and disposes of all the arms, instruments, and utensils of war, both by sea and land, in all magazines, garrisons, and forts in Great Britain. ORES. Metals, when found in a state of combination with other substances, have the name of ores. They are in general deposited in veins of various thickness, and at various depths | in the earth. The mode of obtaining them is to penetrate from the surface of the earth to the vein, and there to follow it, in whatever direction it may lie. The hollow places thus formed are called mines, and the men employed in them are denominated miners. When the veins are at a great depth, or extend to any considerable distance beneath the surface of the earth, it is necessary at intervals to make openings or shafts to the surface, for the admission and circulation of the air; and also to draw off the water which collects at the bottom, by means of drains, pumps, or steam-engines, as the situation or circumstances require. After the metallic ores are drawn from the mine, they in general go through several processes before they are in a state fit for use. in a running water, to clear them from earthy particles. or roasted, for the purpose of ridding them of the sulphur or arsenic with which they may happen to be combined, and which rises from them in a state of fume or smoke. Thus having been freed from impurities, they undergo the operation of melt- ing, in furnaces constructed according to the nature of the respective metals, or the uses to which they are to be subse- quently applied: See Metals. ORFFYREUS's. Wheel, in Mechanics, is a machine so called. from its inventor, which he imagined to be a perpetual motion. This machine consisted of a large circular wheel or 77. * f : Some of them are first washed They are, then piled together with combustible substances, and burnt t drum, twelve feet diameter, and fourteen inches in depth, and very light; it was formed of an assemblage of deals, the intervals between which were covered with waxed cloth, in order to conceal the interior parts of it. The two extremities of an iron axis, on which it turned, rested on two supports. On giving the wheel a slight impulse in either direction, its motion was gradually accelerated; so that after two or three revolutions, it required so great a velocity as to make twenty- five or twenty-six turns in a minute. This rapid motion it actually preserved during the space of two months, in the chamber of the landgrave of Hesse, the door of which was kept locked, and sealed with the landgrave's own seal. At the end of that time it was stopped, to prevent the wear of the materials. The professor, who had been an eye-witness to these circumstances, examined all the external parts of it, and was convinced that there could not be any communication be- tween it and any neighbouring room. Orffyreus, however, was so incensed, that he broke the machine in pieces, and wrote on the wall, that it was the impertinent curiosity of professor Gravesande which made him take this step. The prince, who had seen the interior of this wheel, being asked whether, after it had been in motion some time, there was any change observ- able in it, and whether it contained any pieces that indicated fraud or deception, answered both questions in the negative, and declared, that the machine was of a very simple con- struction. ORGAN, in general, an instrument or machine designed for the production of some certain action or operation; in which sense the mechanic powers, machines, and even the veins, arteries, nerves, muscles, and bones of the human body, may be . * called organs. The organs of sense are those parts of the body by which we receive the impressions or ideas of external ob- jects. being commonly reckoned five, viz. the cyc, ear, nose, palate, audies.ºis. See MAMMALIA, p. 613. ORGAN, a wind instrument blown by bellows, and containing numerous pipes of various kinds and dimensions, and multi- farious tones and powers. Of all musical instruments this is the most proper for the sacred purpose to which it is most ge- nerally applied, in all countries wherever it has been introduced. Its structure is lofty, elegant, and majestic ; and its solemnity, grandeur, and rich volume of tone, have justly obtained it an acknowledged pre-eminence over every other instrument. The church organ consists of two parts; the main body, called the great organ, and the positive or little organ, which forms a buffet, commonly placed before the great organ. The size of an organ is generally expressed by the length of its largest pipe; thus they say, an organ of 8, 16, 32 feet, &c. The organ in the cathedral church at Ulm in Germany, is 93 feet high and 28 broad; its largest pipe is 13 inches diameter, and it has 16 pairs of bellows. ORGANIC ReMAINs. As it is fashionable to dignify various departments of knowledge and human speculation with Greek names, the researches of mankind respecting organic remains have received the pompous name Oryctology. Oryctology is then the science which teaches the natural history of those ani- mal and vegetable substances which are dug out of the earth in a mineralized state. In the following slight sketch of the history of these substances it will be seen that the remarkable situations in which they have been found, and the extraordi- | nary changes which they have undergone, have led to the adop- tion of various contradictory and absurd notions respecting their nature and origin; which have been corrected, as just ideas have been obtained respecting the formation of the earth itself. Xenophanes, more than 400 years before Christ, was led to the belief of the eternity of the universe, by discovering the remains of different marine animals imbedded in rocks and un- der the surface of the earth. Herodotus ascertained the exist- ence of fossil shells in the mountains of Egypt, and was there- by induced to conclude that the sea must have once covered those parts. In the pyramids of Egypt, mentioned by this author, and which has been built at so early a period that no satisfactory accounts could be derived from tradition respecting their erection, the stones were found to contain the remains of marine animals, and particularly of such as exist no longer in a recent state, and differ essentially from all known animals. These were supposed by Strabo, who saw the fragments of 9 E 750 O R. I O R. G. DICTIONARY OF MECHANICAL SCIENCE. these stones lying around the pyramids, to be the petrified re- mains of the lentiis which had been used for food by the work- men. Eratosthenes, Xanthus of Lydia, and Strabo, have all noticed, and variously commented upon, the existence of animal remains thus wonderfully preserved. In the works of Pliny, many fossil bodies are mentioned; particularly the bucardia, resembling an ox's heart, but which was, doubtless, a cast formed in a bivalve shell; glossopetra, bearing the form of a tongue, and supposed to fall from the moon when in its wane : hammites, resembling the spawn of fish ; horns of ammon, re- sembling in form the ram's horn; lepidotes, like the scales of fishes; mecomites, bearing a resemblance to the seeds of pop- pies; brontia, to the head of a tortoise; spongites, to sponge ; phycites, to sea-weeds or rushes. The fossil remains of quadrupeds, especially those of the larger kind, are such as must necessarily excite the attention and wonder of every curious inquirer into natural history. In various parts of this country have been found the remains of elephants, and of other animals of considerable magnitude. In Ireland have been found the remains of deer, of a size far ex- ceeding any now known; and in Scotland have been found the remains of the elk, as well as those of an enormous animal of the ox kind, but larger than even the urus. In France, Ger- many, and Italy, and indeed in most parts of Europe, remains of large animals have been found; and in both North and South America, the remains of enormous unknown animals have been discovered. According to Pallas, from the Tanais to the conti- nental angle nearest to America, there is hardly a river in this immense space, especially in the plains, upon the shores or in the bed of which have not been found the bones of elephants and of other animals not of that climate. From the mountains by which Asia is bounded, to the frozen shores of the ocean, all Siberia is filled with prodigions hones : the best ivory (fns sil) is found in the countries nearest to the arctic vireio, as well as in the eastern countries, which are much colder than Europe under the same latitude; countries where only the surface of the ground becomes thawed during summer. The number of bones which have been discovered of the rhinoceros is very considerable, not only in Siberia, but in Germany, and in other parts of Europe; and in the opinion of St. Fond, founded not only on the discoveries of Pallas and others, but on his own observations made on the immense collection of Merck, joined with that of the landsgrave of Hesse Darmstadt, are of the spe- cies with double horns. An entire body of an animal of this species, still possessing the skin, fat, and muscles, has been dug up near the river Willioni, in the eastern part of Siberia, from under a hill which is covered with ice the greatest part of the year. St. Fond states, in confirmation of the above opinion, that another head obtained by Pallas from Siberia, one exist- ing in the cabinet of the elector of Manheim, and another in the cabinet of Merck, are all apparently similar to the head of the double-horned rhinoceros of Africa. . - Much remains to be ascertained with respect to the fossil remains of elephants, of which considerable numbers have been found in various parts of England, France, Germany, and Italy; but no where so abundantly as in Siberia. In America indeed the remains of enormous unknown species of this ani- mal are also very abundant. There appears to be only two species of elephants now in existence: one (the Asiatic) being distinguished by its grinders being divided into transverse and nearly parallel plates, and the other (the African) having these plates disposed in lozenge-like forms. The elephantine remains which have been found in Siberia have been supposed to have belonged to no existing species; for though the teeth are formed of plates disposed parallel to each other, as in the Asiatic, these plates are said to be thinner, and consequently more numerous; but this distinction is by no means established. The remains of elephants discovered in this country, seem referrible, in most instances, to the Asiatic. The remains of an animal of an enormous size has been found at Paraguay, at no great distance from the river Plata, which being properly ar- ranged, has been formed into a skeleton, and placed in a cabi- net of natural history at Madrid. This animal, twelve feet in length and six in height, is distinguished as well by its general form as by the largeness of its claws. In various parts of Scotland, and of France, in Tuscany, the Veronese, and in North America, have been found the fos- sil remains of some animal, which has been supposed to be a variety of the urus of Julius Caesar, or of the bison. To the fos- sil remains already mentioned, may be added the animal incog- nitum of Symore in Languedoc ; the enormous stag found in the mosses of Ireland; the gigantic tapir, found at the bottom of the black mountains of Languedoc ; the bears, of two spe- cies now unknown, found in Bareith; and the numerous ani- mals, of unknown species, which the admirably indefatigable Cuvier is perpetually discovering, in that mine of fossils, the quarries of gypsum near Paris. Of the mineral remains of man, no well-attested instance is known. In a cavern, indeed, in Mendip Hills, some human bones have been found invested with stalactite; these appear to be but comparatively of modern existence. Scheuchzer published an essay describing a sup- posed skeleton of a man; which was undoubtedly the remains of some large fish. - ORGANICAL DESCRIPTIon of CURves, the method of describing them on a plane by means of instruments, as the compasses and ruler, which are the most simple, and are the only instruments admitted into plane or elementary geometry; but other instruments have been invented for the description of various curves, as elliptic compasses, conchoid, ellipse, hyper- bola, parabola, &c. ORGANZINE, in Commerce, a description of silk usually imported from Italy into this country. It is of the utmost importance to the manufacturer, as none of the principal articles could be fabricated without it; and the Italians, aware of this, long kept the art of throwing it a most profound secret. It was introduced into this country by the enterprise and skill of Messrs. Thomas and John Lombe. - ORIBASIA, a genus of plants belonging to the pentandria class, and in the natural method ranking under the 37th order stellatae. ORIENT, the east or eastern point of the horizon—Orient Equinoctial, that point of the horizon where the sun rises when in the equinoctial.—Orient Estival, is that point of the horizon where the sun rises in the middle of summer.—Orient Hybernal, that point of the horizon where the sun rises in the middle of winter. - ORIENTAL, any thing or place situated to the eastward of an observer. w - ORIGANUM, ORIG ANY, or Marjorum, a genus of plants belonging to the didynamia class, and in the natural method ranking under the 42d order. . . . . ORIGINAL, in the courts of King’s Bench, the usual original writ issued in the actions, as for action of trespass upon the case. This court does not issue originals in actions of debt, covenant, or account, &c. whereas the Court of Common Pleas proceeds by original in all kinds of actions; but to arrest and Sue a party to outlawry, it is used in both cases. : . ORILLON, in Fortification, is a small rounding of earth, faced with a wall, raised on the shoulder of those bastions that have casemates, to cover the cannon in the retired flank, and prevent their being dismounted by the enemy. ' - ORIOLUS, ORIole, in Ornithology, a genus belonging to the order pica. These birds are inhabitants of America, except in a few instances: they are a noisy and gregarious, frugivorous, granivorous, and voracious race, very numerous, and often have pensile nests. The several species, which are very numerous, since Latham describes no less than forty-five, seem to be principally distinguished by their colour. ORION, the most brilliant constellation in the heavens, is highly embellished by several adjacent constellations of great splendour; and, when it comes to the meridian, there is then above the horizon the most splendid vicw of the celestial bodies that the starry firmament affords to the eye of the beholder; and this magnificent exhibition is visible to all the habitable world, because the equinoctial passes nearly through the mid- dle of the constellation.—Boundaries and Contents: N. by Tau- rus; JE. by Monoceros; S. by Lepus, and W. by Eridanus and Taurus. There are seventy-eight stars in this constellation, viz. two of the first magnitude, four of the second, four of the third, sixteen of the fourth, &c. Orion is a paratantellon of Taurus, and the brilliant Betelgeux, on his right. shoulder, of the first magnitude, having 7° 21'54" N. declination, and right O R. P O S C 751 DICTIONARY OF MECHANICAL SCIENCE. ascension 86° 21'.17", appears in the Eastern horizon at Lon- don, on the E. by N. point of the compass, and rises and cul- minates for the first day of every month in the year, as in the following Table: Merid. Alt. 45° 50' 54". . Rises. MonTH, I RISES. CULM. MONTH. CULM -> ho. mi. ho. mi. ho. mi. ho. mi. Jan. 4 30 A. | 10 57 A. July 4, 27 M. 11 2 M. Feb. 2 15 A. | 8 45 A. Aug. 2 25 M. 8 58 M. Mar. 12 25 A. | 6 56 A. Sept. 12 25 M. 6 58 M. April | 10 26 M. 5 3 A. Oct. 10 36 A. | 5 || 4 M. May 8 35 M. 3 12 A. Nov. 8 -55 A. 3 18 M. June 6 25 M. 1 10 A. Dec. 6 45 A 1 14 M. d ORION’s River, another name for the constellation Eri- (1727. S. . - - ORLE, or ORLET, in Architecture, a fillet under the ovole or quarter-round of a capital; when it is at the top or bottom of a shaft, it is called cincture. .- ORLOP, a platform of planks laid over the beams in the hold of a ship of war, whereon the cables are usually coiled. It also contains the sail-rooms, the purser's, surgeon's, boat- swain's, and carpenter's cabins, and the several officers’ store- rooms. In three-deck ships the second and lowest decks are sometimes called Orlops. . ORNITHOGALUM LATI folium and UMBELLATUM, are ornamental plants, and are often cultivated for their beautiful flower. The season for planting the bulbs is about the month of September. - # ORNITHOGALLUM, Star of Bethlehem, a genus of plants belonging to the hexandria class, and in the natural method ranking under the 10th order, coronariae. ORNITHOLOGY, that branch of Zöology which treats of birds. See BIRD. Linnaeus, whose ornithology we have fol- lowed, arranges the whole class of birds under six orders, according to the different figures of their beaks, viz. Accipitres, as eagles, vultures, and hawks; upper mandible with an angu- lar projection. 2. Picae, as crows, jackdaws, humming-birds, and parrots; bill compressed, with feet formed for perching and climbing. 3. Anseres, as geese, ducks, gulls, and swans; bill covered with skin, broad at the tip, some with and some with- out teeth. 4. Grallae, as herons, woodcocks, and ostriches; bill roundish, tongue fleshy: some with three, some with four toes. 5. Gallinae, as peacocks, pheasants, turkeys, and com- mon fowls; bill convex, upper mandible arched. 6. Passeres, as sparrows, larks, and swallows; bills conic, and sharp-pointed. In this iast order are comprehended pigeons. ORNITHOPUS, a genus of plants belonging to the diadel- phia class, and in the natural method ranking under the 32d order, papiliomaceae. * ORNITHORYNCHUS vel. PARADoxus, the bird-quad- ruped from New South Wales, a singular quadruped, which has not yet been properly classed in the Linnean system. The most remarkable circumstance, in this curious animal, is the great similarity of its head with that of a duck; the under part of the mandible having its margin indented, as in ducks; and the proper instrument for chewing being situated behind, within the cheeks. . . . . . . . . . . . - ORNUS FRAXINUS, the ash which produces manna. OROBANCHE, a genus of plants belonging to the didyna- mia class, and in the natural method ranking under the 40th order, personatae. - - . * w OROBUS, Bitter Vetch, a genus of plants belonging to the diadelphia class, and in the natural method ranking under the 32d order, papilionaceae. , - ORONTIUM, a genus of plants belonging to the hexandria class, and in the natural method ranking under the second order, piperitae. * , . . . ORPHAN. . In the city of London there is a court of record established for the care and government of orphans. ORPIMENT, is a mineral substance, of lemon-yellow colour, which consists of arsenic in combination with about forty-three parts of sulphur, and is about thrice as heavy as water. It is found both in a massive and crystallized state, in Natolia, Servia, Hungary, Turkey, and some other countries. In the latter state, the crystals are so confused, that their figures cannot easily be determined. The orpiment of commerce is an artificial production, and is chiefly imported from different parts of the Levant. The Turks and other Orientals use it in the depilatories which serve to render bald the top of the head. A very beautiful but fugitive pigment, called king's yellow, is pre- pared from this mineral, and other preparations of orpiment are occasionally used by painters, and also by dyers and calico-printers. The whole of these, however, are extremely poisonous. ORRERY, an astronomical instrument for exhibiting the motions of the heavenly bodies, was first constructed by Gra- ham, but its name is derived from one made by Rowley for the Earl of Orrery, which was supposed by Sir R. Steel to be the first ever constructed; and he therefore gave it the above name in honour of the Earl, and attributes the invention to Mr. Row- ley; whose name it has ever since retained, though the error on which it was adopted has long been corrected. ORRIS-ROOT, is the root of a white-flowered kind of iris, called Florentine Iris, which is a native of Italy, and is dis- tinguished by having two flowers on each stalk; the petals bearded, and the leaves sword-shaped. In a dried state, this root is well known on account of its grateful odour, which somewhat approaches that of the violet. It is consequently much used in the manufacture of hair powder, and other arti- cles for which an agreeable scent is required. It is sometimes employed in medicine as a pectoral or expectorant, and some- times in dropsies. In a recent state the root is extremely acrid ; and, when chewed, excites in the mouth a pungent taste, which continues for several hours; but this acrimony is almost wholly dissipated by drying. Orris-root is chiefly im- ported into this country from Leghorn. ORTHODROMICS, in Navigation, is the same as Great Cir- cle Sailing, and indicates the straight or shortest distance, which can only be in the arc of a great circle. ORTHOGRAPHIC PROJection of the Sphere, is that projection which is made upon a plane passing through the middle of the sphere, by an eye placed vertically at an infinite distance. g ORTHOGRAPHY, that part of grammar which teaches the nature and affections of letters, and the just method of spelling or writing. - - ORTHOGRAPHY, in Geometry, the art of drawing or delineating the fore-right plan of any object, and of expressing the heights or elevations of each part. It is called orthography, from its determining things by perpendicular lines falling on the geometrical plane. ORTHog RAPHY, in Architecture, the elevation of a building. ORTHo GRAPHY. See Perspective. ' . ORTIVE, or EASTERN AMPI.itude, in Astronomy, is an arch of the horizon intercepted between the place where a star rises and the east point of the horizon. ORTOLAN. See EMBERIZA. * ORYZA, Rice, a genus of the dyginia order, in the hexandria class of plants; and in the natural method ranking under the 4th order, gramina. There is but one species, namely, the sativa or common rice. This plant is greatly cultivated in most of the Eastern countries, where it is the chief support of the inha- bitants; and great quantities of it are brought into England and other European countries every year, where it is much esteem- ed for puddings; &c. it being too tender to be produced in these northern countries without the assistance of artificial heat: but from some seeds which were formerly sent to Carolina, there have been great quantities produced, and it is found to succeed there as well as in the Eastern countries. It has been cultivated with advantage in Lombardy in Italy; but the stagnant water in which it grows being injurious to health, the government does not permit the extension of the cultivation to new lands. OSCILLATION, in Mechanics, vibration, or the reciprocal ascent and descent of a pendulum. * , Azis of Oscillation, is a right line passing through the point of suspension parallel to the horizon. .- , Centre of Oscillation, is that point in a vibrating body into which, if all the matter of the body were collected, the vibra- tions would be performed in the same time. OSCULATION in the theory of Curves, denotes the contact between any curve and its osculatory circle; on that circle which has the same curvature as the curve at the given point of 752 U S T O U T DICTIONARY OF MECHANICAL SCIENCE, osculation. If A C be the evo- lute of the involute curve. A E, F, and the tangent, C E the radius. of curvature at the point E, with which and the centre C, if the circle B E G be described, this B circle is said to osculate or kiss the curve A EF, in the point E; which point E is called the point of osculation; C E the oscula- tory radius, or radius of curva- ture: the circle B E G the osculatory circle; and the evolute | A C the locus of all the centres of the osculatory circles. Point of osculation is also used to denote the concourse of two branches of a curve that touch each other; which differs from a cusp or point of retrocession, in this, that in the latter case, although it forms a point of concourse, the curve terminates there; whereas in a point of osculation, the curve does not terminate, but is con- tinued on both sides. Thus, in the annexed figure, A is a point of retro- - - cession, and B a point of osculation. . - OSCULATORY CIRCle, or Kissing CIRCLE, is the same as the circle of curvature ; such is the circle B E G in the prece- ding figure, article OSCULATION. - - - OSIER, a very valuable shrub, of the salix viminales, used. principally in basket-making. - - , " . OSMIUM. A new metal lately discovered by Mr. Tenant among platina, and thus called by him from the pungent and pe: culiar smell of its oxide. Pure metal, previously heated, did, not appear to be acted upon by acids, Heated in a silver cup with caustic alkali, it combined with it, and gave a yellow solution similar to that from which it was procured. From this solution acids separate the oxide of osmium. OSMUNDA, Moonwort, a genus of plants belonging to the cryptogamia class. - - * * * - - OSSIFICATION. The deposition of the phosphate and carbonate of lime on the soft solids of animal bodies, as, on the lungs, liver, heart, &c. - - - . . . - OSTENSIVE DeMonstration, is a direct geometrical de- which depends upon a reductio ad absurdum. OSTRACTION, Trunk-fish, a genus of fishes, of the order nantes; the generic character is, teeth pointing forwards, cylindric, rather blunt; body mailed by a bony covering. OSTREA, the Oyster, in Zöology, a genus belonging to the order of vermes testacea. There are thirty-one species, prin- cipally distinguished by peculiarities in their shells. The com- mon oyster is reckoned an excellent food, and is eaten both raw and variously prepared. The oyster differs from the mus- cle in being utterly unable to change its situation. It is entirely. without a tongue, which answers the purposes of an arm in the monstration, in contradistinction to an apogogical one, or that. other animal, but nevertheless is often attached very firmly to. any object it happens to approach. Oysters usually cast their. spawn in May, which at first appears like drops of candle- grease, and sticks to any hard, substance it falls upon. These are covered with a shell in two or three days; and in three. years the animal is large enough to be brought to market. As they invariably remain in the places where they are laid, and, as they grow without any other seeming food than the afflux of sea-water, it is the custom at Colchester, and other parts of England, where the tide settles in marshes on land, to pick up great quantities of small oysters along the shore, which, when first gathered, seldom, exceed the size of sixpence. These are deposited in beds where the tide comes in, and in two or three.| years grow to a tolerable size. They are said to be better tasted for being thus sheltered from the agitations of the deep; and a mixture of fresh water entering into these repositories, is said to improve their flavour and increase their growth, and fatness. The oysters, however, which are prepared in this. manner, are by no means so large as those found sticking to rocks, at the bottom of the sea, usually called rock-oysters.' These are sometimes found as broad as a plate, and are admired by some as excellent food. But what is the size of these compared to the oysters of the East Indies, some of: wbose shells have been seen two feet over ? The oysters found: along the coast of Coromandel, are capable of furnishing a . plentiful meal for eight or ten men; but it seems universally agreed that they are no way comparable to ours for delicacy of flavour. . . . . . - OTACOUSTIC, a name sometimes given to a hearing trum. pet and other instruments for improving the sense of hearing. OTIS, the Bustard, in Natural PHistory, a genus of birds of the order gallina. Gmelin mentions eleven species, and Latham nine. We shall notice only the following:—The great bustard, found in the plains of Europe, Asia, and Africa, but has never been observed in the New Continent. In England it is occasionally met with on Salisbury Plain, and in the wolds of Yorkshire, and formerly was not uncommonly seen in flocks of forty or fifty. It is the largest of British land birds, weigh- ing often twenty-five or thirty pounds. It runs with great rapidity, so as to escape the pursuit of common dogs, but falls speedily a victim to the greyhound, which often overtakes it before it has power to commence its flight, the preparation for which, in this bird, is slow and laborious. The female lays her eggs on the bare ground, never more than two in number, in a hole scratched by her for the purpose; and if these are touched or soiled during her occasional absence, she immedi- ately abandons them. The male is distinguished by a large pouch, beginning under the tongue, and reaching to the breast, capable of holding, according to Linnaeus, seven quarts of . water. This is sometimes useful to the female during incu-. bation, and to the young before they quit their nest; and it has been observed to be eminently advantageous to the male bird himself, who on being attacked by birds of prey, has often discomfited his enemies by the sudden and violent discharge of water upon them. These birds are solitary and shy; and feed principally upon grasses, worms, and grain. They were formerly much hunted with dogs, and considered as supplying : no uninteresting diversion. They swallow stones, pieces of metal, and other hard substances. Buffon states that one was opened by the academicians of France, which contained in its stomach ninety doubloons, and various stones, all highly smoothed by the attrition of the stomach. The little bustard is met with in many parts of Europe, particularly in France, where it is taken by nets. It is rarely seen in England, is shy and cunning; if molested, will fly about two hundred paces, and then run so fast that a man cannot overtake it. Its flesh is like that of the great bustard, rich and delicate, and it would appear worth while to attempt the domestication of both these birds. - OTTER. See MustELA. - º OUNCE, a little weight, the sixteenth part of a pound avoirdupois, and the twelfth part of a pound troy; the ounce avoirdupois, is divided into eight drachms, and the ounce troy into twenty pennyweights. OUNge. See Felis. - OUTFIT, implies the expenses of equipping a ship out for Sea. • . - OUT of TRIM, the state of a ship when she is not properly balanced for the purposes of navigation, which may be occa- sioned by a defect in the rigging, or in the stowage of the hold. OUTLAWRY, the punishment of a person who being called into law, and lawfully sought, according to the usual forms, does contemptuously refuse to appear. The effect of being outlawed at the suit of another, in a civil case, is the forfeiture of all the outlaw's goods and chattels to the king, and the pro- fits of his lands while the outlawry is in force. OUTLICKER, a small piece of timber made fast to the top of the poop, and standing out right astern. - OUTRIGGER, a strong beam of timber, of which there are several, fixed on the side of a ship, and projecting from it, in order to secure the masts in the act of careening, by counter- acting the strain it suffers from the effort of the careening ;tackles, which being applied to the mast head, draw it down. wards, so as to act upon the vessel with the power of a lever, whose fulcrum is in her centre of gravity. • OUTRIGGER, is also a small boom, occasionally used in the tops, to thrust out the breast backstays to windward, in order O W E O W I DICTIONARY OF MECHANICAL SCI ENC fº. 753 to increase the angle of tension, and thereby give an additional security to the topmast. It is usually furnished with a tackle at its inner end, communicating with one of the topmast shrouds, and has a notch on the outer end to contain the back- stay, and keep it steady therein. As soon as the backstay is is applied aloft, which it forces out to windward, beyond the circle of the top, so as to increase the angle which the mast makes with the backstay, and accordingly enables the latter the better to support the former. This machine is sometimes applied without any tackle; it is then thrust out to its usual dis- tance beyond the top rim, wherein it is securely fastened; after which, the backstay is placed in the notch, and extended below. OUTWARD, in Navigation, implies out of the port, or king- dom, as, “the outward-bound ships, as by my last letter.” OUTWORKS, in Fortification, all those works made with- outside the ditch of a fortified place, to cover and defend it. Outworks, called also advanced and detached works, are those which not only serve to cover the body of the place, but also to keep the enemy at a distance, and prevent his taking advantage of the cavities and elevations usually found in the places about the counterscarp, which might serve them either as lodgments, or as rideaux, to facilitate the carrying on their trenches, and planting their batteries against the place; such are ravelines, tenailles, horn-works, velopes, crown-works, &c. OVAL, an oblong curvilinear figure, having two unequal dia- meters, and bounded by a curve line returning into itself. Un- der this general definition of an oval is included the ellipse, which is a regular oval; and all other figures which resemble the ellipse, though without possessing its properties, are classed under the same general denomination. > We have shewn under the article ELLIPSE, different mechanical methods of describing ellipses; and we shall therefore only give in this place a practical method of describing an oval, which to the eye very much resembles the conical ellipse; this is as follows;–Set the given length A B at right angles to the breadth CD, so that they bisect each other perpendi- cularly at E ; with the centre C and radius A E describe an arc to cross A B, in F and G, and with the radii A F and B G, describe two little arcs, and H I and KL for the smaller ends of the oval; and then with centres C and D, and radius CD, describe the arcs H C K and ID L, for the flatter or larger arcs of the figure. - OVERBLOW, is when the wind blows so very hard that the ship can bear no top-sails. OVERBOARD, the state of being thrown out, or the act of falling from a ship or boat into the water on which she swims; as, there is a man overboard, he threw her guns overboard, &c. Overcast Staff, a scale or measure, employed by ship- wrights to determine the difference between the curves of those timbers, , which are placed near the greatest breadth, and those which are situated near the extremities of the keel, where the floor: rises and grows narrower. - OVERGROWN, is said of the sea when the surges and billows are unusually high; but when the waves are no more than commonly high, it is called a rough sea. OVERHAULING, the act of opening and extending the several parts of a tackle or other assemblage of ropes, com- municating with blocks or dead-eyes, so that they may be again placed in a state of action. . - - OverHAULING, also implies an examination of a ship, per- son, or thing, One ship is said to overhaul another, when she gains fast upon her in chace. - QWERMASTED, the state of a ship whose masts are too high, or too heavy, for the weight of her keel to counterbalance. OWERRAKE, when a ship rides at anchor in a head sea, the waves of which frequently break in upon her, they are said to overtake her. OVERSEERS of the Poor. By 43 Elizabeth, c. 2, § 1, the churchwardens of every parish, or two substantial householders, to be nominated yearly within fourteen days after the 25th of Mºh, under the hand and seal of two justices of the peace of the county, shall be overseers of the same parish. In gene- ral, all persons are liable to serve, with some exceptions as to peers of the realm, clergymen, parliament men, attorneys, practising barristers, the president and members of the college tº & º of physicians, surgeons, and apothecaries free of the halī; drawn tight by means of its tackles in the chains, the outrigger || dissenting ministers, prosecutors of felons having a Tyburn ticket, and soldiers actually serving in the militia. In exten- Sive parishes, a great number of overseers are appointed under 13 and 14 Charles II. c. 12, § 21; and by 17 George II. c. 38, if an overseer dies, removes, or becomes insolvent, the justices may appoint another, and their appointment is subject to appeal to the sessions. By 43 Elizabeth, c. 2, § 2, overseers shall within fourteen days after the appointment of new ones, deliver to them an account to be allowed by two justices, and pay over balances due from them, which, if not paid, may be levied by distress, and the party committed to prison by the justices until the balance is paid, and the account delivered in ; and by 17 George II. c. 38, the account is to be verified by oath. If he removes, the overseer is to account in like man- ner. If he dies, his executors have forty days to account, and must pay the balance before any other debts. Their duty con- sists in raising the poor's-rates, taking care of the poor, giving relief to casual poor, and removing improper persons who have become actually chargeable and have no legal settlement. They are also to bind out the children of poor persons, and in that case the infant parish apprentice and his master cannot vacate the indentures without the overseers. They are also to pro- cure orders of maintenance of bastards to be made, and bonds to be taken from the reputed father to indemnify the parish. It has been usual for overseers in those cases, instead of taking a bond of indemnity, to accept of a sum of money, and discharge the father. But this has been lately held to be illegal, because it gives the overseers an interest to procure the death of the child. In cases of removal also, overseers should be careful not to execute the order in a harsh and improper manner, for if a person die in consequence of a removal at a time of sick- ness, the overseer may be guilty of murder, and liable to an indictment. Overseers also should not improperly conspire to force persons who are with child of bastards, to marry and relieve the parish, for this also is indictable. By 17 George II. c. 38, if any person shall be aggrieved by any thing done or omitted by the churchwardens and overseers, or by any of his majesty's justices of the peace, he may, giving reasonable notice to the churchwardens or overseers, appeal to the next general or quarter sessions, where the same shall be heard, or finally determined; but if reasonable notice be not given, then they shall adjourn the appeal to the next quarter sessions; and the court may award reasonable costs to either party, as they may do by 8th and 9th William, in case of appeals concerning settlements. See Poor. By 43 Elizabeth, c. 2, § 2, they forfeit 20s. on neglecting to meet in the vestry one Sunday in the month; and by 13 and 14-Charles II. c. 4, forfeit £5 for refus- ing relief to a person duly removed by warrant of two justices. By 9 George III. c. 37, § 7, they are to forfeit 10s. or 20s. for paying the poor in bad money, OVERSETTING, the act of turning any thing upside down: also the movement of a ship, when her keel turns upwards; which misfortune happens either by bearing too much sail, or by grounding her so that she falls on one side. OVERT, the same with open. Thus an overt act signifies an act which, in law, must be clearly proved; and such as is to be alleged in every indictment for high treason. OVIS, Sheep, a genus of the order pecora, usually the most timid of quadrupeds. When sheep, however, have an exten- sive range of pasture, and are left in a considerable degree to depend upon themselves for food and protection, they exhibit more respectability of character. A ram has been, seen in these circumstances to attack and beat off a large and formid- able dog, and even a bull has been felled by a stroke received between his eyes, as he was lowering his head, to receive his adversary on his horns, and toss him into the air. ...When individual efforts are unequal to the danger, sheep will unite their exertions, placing the females and, their young in the middle of an irregular square; the rams will station themselves so as to present an armed front on every side to the enemy, and will support their ranks in the crisis of attack, harassing 9 F 754. ' o Y E o X, Y DICTIONARY of MECHANICAL SCIENCE. the foe by the most formidable and sometimes fatal blows. sheep display considerable sagacity in the selection of their food, and in the approach of storms they perceive the indi- cations with accurate precision, and retire for shelter, always to the spot which is best able to afford it. The domestic sheep is scarcely ever found (excepting in temperate latitudes) in a state approaching to perfection. In hot regions its wool dege- nerates into a species of hair, and in rigid climates, though the wool is fine at the root, it is coarse towards the surface. OWNER, the proprietor of any thing, as of a ship, by whom she is freighted to the merchant for a sea voyage. e OX, in Zöology, is a generic term, synonymous with Bos; including both the male and female. Few species, however, of this tribe appear to be really distinct. Their variations arise from climate, domestication, and other causes, which it would be tedious to enumerate. In modern language, the word ox is confined to the male species of meat cattle that have undergone mutilation by the hands of man. In this sense, the animal is too well known to require any particular description, either of its natural history, its formation, or its utility. OXALATES. Compounds of salifiable bases with the oxalic acid. . . OXALIC ACID. This acid, which abounds in wood sorrel, and which, combined with a small portion of potash, as it exists in that plant, has been sold under the name of salt of lemon, to be used as substitute for the juice of that fruit, particularly for discharging ink spots and iron-moulds, was long supposed to be analogous to that of tartar. The oxalic acid, is a good test for detecting lime, which it separates from all the other acids, unless they are present in excess. It has likewise a greater affinity for lime than for any other of the bases, and forms with it a pulverulent insoluble salt, not decomposable except by fire, and turning syrup of violets green. Oxalic acid acts as a violent poison when swallowed in the quantity of two or three drachms; and several fatal accidents have lately occurred, in consequence of its being improperly sold instead of Epsom salts. The immediate rejection from the stomach of this acid, by an emetic, aided by copious draughts of warm water containing bicarbonate of potash, or soda, or chalk, or carbonate of magnesia, are the proper remedies. The stomach pump has of late been successfully used in discharging this poison. See SYRINGE. OX-EYE, a small cloud or meteor, seen at the Cape of Good Hope, which presages a dreadful storm. It appears at first in the form or size of an ox’s eye, but descends with such celerity, that it seems suddenly to overspread the whole hemi- sphere, and at the same time forces the air with such violence that ships are sometimes scattered several ways, some directly contrary, and many sunk downright. OXGANG, or OxgATE, is generally taken, in our old law books, for fifteen acres, or as much ground as a single ox can plough in a year. . OXIDATION. The process of converting metals, or other substances, into oxides, by combining with them a certain por- tion of oxygen. It differs from acidification, in the addition of oxygen not being sufficient to form an acid with the substance oxided. - OXIDE, CARBON1c. When a mixture of purified charcoal and oxide of iron or zinc is exposed to a strong heat in an iron retort, the metallic oxide is gradually reduced, and, during the reduction a great quantity of gas is evolved. This gas is a mixture of carbonic acid gas, and another which burns with a blue flame. This last is carbonic oxide. OxIDEs. Substances combined with oxygen, without being in the state of acid. º OXYDE, or Oxide, a chemical term denoting a very numerous class of bodies, formed by the union of certain bases, with a smaller proportion of oxygen than what is necessary for their conversion into acids. Metals oxydize by combustion, solution in acids, and exposure to the air, rain, &c. as in the case of rust of iron, which is an oxide. OXYGEN, is a constituent part of the atmospheric air, of water, of acids, and of all bodies of the animal and vegetable kingdoms; combined with light and heat, and as oxygen gas, it approaches nearest to purity, Oxygen is only known in combination with other bodies and has not been obtained alone. When absorbed by combustible bodies, it converts : them into acids. It is necessary to combustion, uniting itself always to bodies which burn, augmenting their weight, and changing their properties. It is necessary also to the respira- , tion of animals. To procure oxygen gas, a quantity of man- ganese is produced into a glass retort, furnished with a ground stopper; a quantity of oil of vitriol (sulphuric acid,) sufficient to moisten the manganese, is added, and they are mixed toge- ther by means of a glass rod; the bottom of the retort is then gently heated by means of a lamp, and the extremity of its neck introduced under an inverted cylinder, filled with water in the hydro-pneumatic apparatus. Globules of gas will soon rise ! through the water; the first portions collected must be thrown away, being principally the common air contained in the re- tort; when a quantity equal to the capacity of the retort has been thus disposed of, the remainder may be preserved for use. There are many other modes of obtaining oxygen gas; the same manganese, heated to redness in an iron tube, such as a gun-barrel, the touch-hole of which is closed, will afford a con- siderable quantity of the substance, which may be collected by means of a tube fastened into the neck of the barrel, and hav- ing its extremity in the hydro-pneumatic apparatus. Nitre heated strongly in a porcelain retort, gives off oxygen gas; puce-coloured or red oxide of lead offers a similar result; and from any of the salts called hyper-oxymuriates, oxygen is pro- cured by a dull red heat; a retort of glass may be employed in the process; and a charcoal fire in a small chafing-dish. One hundred grains of the hyper-oxymuriate of potassa, afford about one hundred and fourteen cubical inches of oxygen gas, under common circumstances. Oxygen gas may be procured in the hydro-pneumatic apparatus from zinc or iron filings, by means of oil of vitriol diluted with eight times its weight of water; a retort, or a bottle furnished with a tube, may be used; no artificial heat is required in the process. It may like- wise be produced by passing steam over turnings of iron heated to redness in a gun-barrel. Oxygen gas, combined with hydro- gen, forms water; with nitrogen, common atmospheric air ; with sulphur, phosphorus, &c. sulphuric acid, phosphoric acid, &c.; alone it has neither smell nor taste. Oxygen gives the sharp, acrid character to those which are called acids. It com- bines with metals, destroys their metallic lustre, and gives them. an earthy or rusty appearance. These substances are called oxides, and they are all heavier than the metals from which they are formed. Oxygen readily enters into combination, and no substance is more active as a chemical agent. It is known to be a constituent part of most of the acids and earths, and of all the alkalies except one, and the history of its com- pounds forms the most extensive and important part of modern chemistry. The operations of oxygen are connected with many of the arts; with the processes of bleaching, dying, colour- making, and metallurgy; and in its various applications to the production of fire, it is absolutely essential to cultivation, and, to the comforts and enjoyments of social life. - OXYMEL. A compound of honey and vinegar. . . OXY MURIATES. Compounds of the chloric acid with salifiable bases. The oxymuriate of mercury is corrosive sub- limate. The oxymuriate or chloride of alumina has been used. in discharging Turkey red. OXYMURIATIC ACID GA.S. See CHLoRINE. OYER of DEED, is when a man brings an action upon a deed, bond, &c. and the defendant appears, and prays that he may hear the bond, &c. where with he is charged, and the same. shall be allowed him ; and he is not bound to plead till he has it, paying for the copy of it. The time allowed for the plain- tiff to give oyer of a deed, &c. to the defendant, is two days exclusive after it is demanded. Carth. 454. 9 Durnf, and East. 40. - OYER AND TERMINER, is a court held by virtue of the king’s commission to hear and determine all treasons, felonies, and misdemeanors. This commission is usually directed to two of the judges of the circuit, and several gentlemen of the county; but the judges only are of the quorum, so that the rest cannot act without them. 4 Black. 269. See Assizes. O YES, corrupted from the French oyez, hear ye; is an ex- pression used by the crier of a court, in order to enjoin silence when any proclamation is made. . DiCTION A. R.Y. OF MECHANICAL SCIENCE, 755 - P. f P 2 as an abbreviation, among Astronomers, stands for post, after ; as P. M. post meridian, i.e. after 12 at noon. P, with physicians, signifies pugil, a handful, or pulvis, powder. PABULUM of PLANTS. No one principle affords the pabulum of vegetable life; it is neither charcoal, nor hydrogen, nor azote, nor oxygen, alone; but all of them together, in various states and combinations, r - PACE, two and a half feet; but the geometrical pace is 5 feet, and 60,000 such pages make one degree of the equator. . PAce, in the Manege, is of three kinds, the Walk, trot, or gallop. PACK, in Commerce, is a horse's load; as, a pack of wool, which is 17 stone 21bs. Hence from pack, we have— PACKAGE, the duty of one penny in the pound paid for all goods not particularly rated. . . . r PACKERS, persons whose employment it is to pack up all goods intended for exportation,; which they do for the great trading companies and merchants of London, and are answer- able if the goods receive any damage through bad package. PACKET BoAT, a vessel appointed by government to carry the mail of letters, packets, and expresses, from one part of the kingdom to another by sea, or to the colonies, in the most expe- ditious manner, This service is now very expeditiously exe- cuted by the steam packets. - PACOS. See CAMELUs. PADDOCK Course, a piece of ground with pales or a wall, and taken out of a park for exhibiting races with greyhounds, for plates, wagers, and the like. This area is generally a mile in length and a quarter of a mile broad. - PADDock, in Agriculture, signifies nothing more than a small field or enclosure. It is also a name given to a large toad or frog. PAEDEROTA, a genus of plants, of the pentandria class; and in the natural method ranking with the 30th order, contortae. PAEONIA, Pio NY, a genus of plants belonging to the polyan- dria class; and in the natural method ranking under the 26th order, multisiliquae. PAGAN, from the Latin pagus, a villager, not a citizen. PAGAN, BLAIs E FRANcois CoMTE DE, a very eminent French mathematician and engineer, was born at Avignon in Provence, in 1604, and died in 1665, in the sixty-first year of his age. Pagan was most distinguished in his military charac- ter, and for the works which he wrote on the theory of fortifi- cation; but his other performances are also very honourable testimonies of his scientific acquirements. PAGANISM, the religion of the heathen nations, in which the Deity is represented under various forms, and by all kinds of images, or idols; it is therefore called idolatry, or image worship. The theology of the pagans was of three sorts, viz. fabulous, natural, and political or civil. The first treats of the genealogy, worship, and attributes of their deities; who were for the most part the offspring of the imagihation of poets, painters, and statuaries. To their gods were given different attributes, ascribing to them every species of vice, as well as to some of them every virtue. PAGE, a youth of state, retained in the family of a prince or great personage, as an honourable servant to attend in visits of ceremony, carry messages, bear up trains, robes, &c. and at the same time to have a genteel education, and learn his exercises. PAGOD, or PAGoDA, a name whereby the East Indians call the temple in which they worship their gods. The pagod usually consists of three parts; the first is a vaulted roof, sup- ported on stone or marble columns: it is adorned with images; and being open, all persons without distinction are allowed to enter it. The second part is filled with grotesque and mon- Strous figures, and no person is allowed to enter it but the bramins themselves. The third is a kind of chancel, in which the statue of the deity is placed. It is shut up with a very strong gate. PAGoD, or Pagoda, is also the name of a gold or silver coin, current in several parts of the East Indies, value 5s. \ e PAIN, an uneasy sensation, arising from a sudden and vio- lent solution of continuity, or other accident, in the nerves, membranes, vessels, &c. From the sense of feeling, as well as ali the other senses, either pain or pleasure may arise; nay, to this Sense we commonly refer both pain and almost all other trou- blesome sensations, though in truth pain may arise from every vehement sensation. It is brought on by any great force applied to the sentient part; whether this force comes from within or from without. Whatever therefore pricks, cuts, Iacerates, distends, compresses, bruises, strikes, gnaws, burns, or in any manner of way stimulates, may create pain. Hence it is so frequently conjoined with so many diseases, and is often more intolerable than even the disease itself. A moderate degree of pain stimu- lates the affected part, and by degrees the whole body; pro- duces a great flux of blood to the part affected, by increasing the action of its vessels; and it seems also to increase the sen. sibility of the part affected to future impressions. It often sti- mulates to such motions as are both necessary and healthful. Hence, pain is sometimes to be reckoned among those things which guard our life. When very violent, however, it produces too great irritation, inflammation, and its consequences, fever, and all those evils which flow from too great force of the circu- lation; it disorders the whole nervous system, and produces Spasms, watching, convulsions, delirium, debility, and fainting. Neither the mind nor body can long bear very vehement pain; and indeed nature has appointed certain limits, beyond which she will not permit pain to be carried, without bringing on delirium, convulsions, syncope, or even death, to rescue the miserable sufferer from his torment. Long continued pain, even though in a more gentle degree, often brings on debility, torpor, palsy, and rigidity of the affected part. But if not too violent, nor accompanied with fever, sickness, or anxiety, it Sometimes seems to contribute to the clearness and acuteness of the judgment, as some people testify who have been afflicted with the gout. PAINTING, is the art of representing all objects of nature visibly, by lines and colours, on a plain surface; and may be divided into Invention, Composition, Design, and Colouring. See DRAWING. Invention consists generally in the choice of such subjects as are best calculated to answer some great and interesting end,— Composition regards the arrangement of the subject both as to forms, and to the general effects of light and shade, and of colour.—The important objects which Design embraces, will be found under that article. See DESIGN. Colouring regards first, the infinite variety of hues with which nature distinguishes her forms, agreeably to the degree and mixture of the rays of light which their surfaces reflect; and secondly, the distribution, apposition, and accompaniment, of various hues or tints, to produce the effect most pleasing to the sight, a circumstance in which nature does not always delight. Colouring.—It is the duty of the colourist to consider, that as there are two sorts of objects, the natural or real, and the artificial or painted; so there are also two sorts of colours, viz. the natural, or that which makes all the objects in nature visible to us; and the artificial, or that which, by a judicious mixture of simple colours, imitates those natural ones in all their various situations and circumstances. Several colours which, placed unmixed by one another, have a kind of aerial brightness, when mixed together produce a disagreeable earthy colour; for in- stance, ultramarine with fine yellow, or fine vermilion. Colours, which by mixture lose strength and become harmonious, are called broken colours, and contribute as greatly to the sweet- ness and softness of tones in pictures, as they subtract from their brightness. t Chiaro Seuro.—The art of chiaro-scuro consists, 1st. In con- necting and combining the figure or objects of a composition in such masses of light and of shade as are both the most pleas- ing to the eye, and best calculated for the just development and display of the subject. 2d. In assigning to each object the 756 P A I P A I DICTIONARY OF MECHANICAL SCIENCE. colour most corresponding (on account of the force or qualities above mentioned) to its respective place in the general mass or group, and at the same time best harmonizing with the other colours of the picture, either by its natural and proper tone, or by the reflected hues which it receives from adjoining, or sur- rounding objects. The beauty of these reflexes depends on the skilful adaptation of transparent or opaque colours. .3d. In the judicious introduction of such accidents as contribute to strengthen the general effect and character of the work. Composition.—Composition may be divided into the general distribution of objects, the grouping, the choice of attitudes, the contrast, the cast of draperies, and the management of the back ground, or the connexion of the whole effect. In compo- sition, as far as regards the general distribution of objects, the painter ought to contrive, that the spectator may, at the first sight, be struck with the general character of the subject, or at least may comprehend its principal scope. This effect is most readily produced, by placing the most essential figures in the most conspicuous places, provided it can be done without violence or impropriety. Besides this distinctness in the general expression of the subject, the beauty of the composition will depend on the variety, connexion, and contrast, displayed in the distribution of objects; provided, in like manner, that these are conformable to the nature of the subject, whether gay, familiar, full of motion and hurry, or still, solemn, and melancholy. The grouping regards both design and chiaro- scuro. In the former, it respects the figures principally con- cerned in the expression of the subject, which must necessarily be near to or distant from one another, as their actions, con- versations, or other mutual relations, require. In the latter, it regards those masses which are formed from objects which may be properly arranged together, and those effects of light and shade which are formed in consequence of such assemblage or union. These are the points to which the attention must be principally and diligently directed in forming the groups of a composition. The choice of attitude is the principal subor- dinate division of grouping. Whatever attitude is given, it must not only contribute its due portion to the completion of the group, but the greatest care must be taken by the painter, that it does not appear to be introduced for that purpose merely. It must be appropriate to the character of the indi- vidual figure, and expressive of its requisite action; and it must at the same time combine whatever beauty of form can be shewn by such a selection of turns or views of the body, as the necessary circumstances will admit. The knowledge of generic characters, under the various modifications of sex, age, and condition; of the various operations of the passions in the human mind; and a thorough acquaintance with the circum- stances of the history, or other subjects to be represented, are the best guides to a good choice of attitudes. Of the different Classes of Painting.—Painting is chiefly divided into historical, (comprehending allegorical and mysti- cal,) grotesque, portrait, fancy, animals, fruits and flowers, battles, landscape, sea views, architecture, and still life. The subordinate divisions of all these are endless. Grotesque paintings are to be found in the celebrated Loggia of the Vati- can palace at Rome, painted from the designs of Raffaelle, and in the ceiling of the portico of the Capitol, carved from those of Michael Angelo. Of portrait, as being a branch of painting to which our country is peculiarly addicted, it is requisite to give a more detailed account. ; Portraiture.—The greatest perfection of a portrait is extreme likeness, and the greatest fault is the resemblance of a person. for whom it was not designed, unless we are inclined to except a still more grievous defect, viz. the want of resemblance to any person whatever. - The different modes of painting now in use are:—Oil paint- ing; preferable to all other methods, as it admits of a perfect gradation of the tints in the most durable of all materials, except those of Mosaic painting. Fresco painting; which is performed with colours diluted in water, and laid on a wall newly plastered, with which they incorporate, and are some- times as durable, as the stucco itself. Crayon painting; in which colours, either simple or compound, are ground in water mixed with gum, and made into small rolls of a hard paste, which are then used on paper or parchment. Miniature paint. ing; which consists of colours prepared with water or gum, and laid on vellum or ivory. Enamel painting ; which is per- formed on copper or gold, with mineral colours, dried by fire. This method is also very durable. , Wax, or encaustic paint- ing; performed by the mixture of wax with the varnish and colours. Painting on glass, too well known to need descrip- tion, and performed by various methods. Painting in distem- per; which is with colours mixed with size, white of eggs, or any thin glutinous substance, and used on paper, linen, silk, board, or wall. Painting in water colours, more properly called limning : it is performed with colours mixed with water, gum, size, paste, &c. on paper, silk, and various materials. To these is to be added elydoric painting, consisting of a mixed use of oil colours and waters. Method of Painting in Fresco.—Before you begin to paint, it is necessary to apply two layers of stucco on the place where your work is to be executed. If you are to paint on a wall of brick, the first layer is easily applied; if of freestone closely joined, it is necessary to make excavations in the stone, and to drive in nails or pegs of wood, in order to hold the layer together. The first layer is made of good lime and a cement of pounded brick, or, which is better, river sand, which latter forms a layer more uneven, and better fitted to attach the second smooth layer to its surface. When the first layer is perfectly dry, wet it again with water, in proportion to its dry- ness, that the second layer may more easily incorporate with it. The second layer is composed of lime, slaked in the air, and exposed for a whole year, and of river sand of an equal grain, and moderately fine. The surface of this second layer must be uniformly even. To give a fine polish to this surface, a sheet of paper should be applied on it, and the trowel passed and repassed over the paper. The workman must not extend the layer over a greater space than the painter is able to finish in a day, as it is necessary that the ground should always be fresh and moist under his pencil. The ground being thus prepared, the painter begins his work; but as painting in fresco must be executed rapidly, and as there is not time to retouch any of the strokes of the brush with good effect, he will first have taken care to provide himself with large finished drawings in chalk, or paintings in distemper, of the same size as the work which he has to paint, so that he shall have only to copy these draw- ings on the wall. The painter traces the outlines of the figures on the plaister, by passing a steel point over them, or pricking them closely, and passing very finely powdered charcoal through the pricked holes. All natural earths are good for painting in fresco. The colours are ground, and tempered with water. It is to be remarked, that all the colours used in this method of painting brighten as they grow dry, excepting the pavonazzo, or red varnish, the brownish red ochre, ruth ochre, and the blacks, particularly those that are passed through the fire. The best colours are white, made of old lime and white marble dust, (the proportional quantity of the latter depends on the quality of the lime, and must be found by trial, as too great a quantity of marble dust will turn the colour black,) ultramine blue, the black of charcoal, yellow ochre, burnt vitriol, red earth, green of Verona, Venetian black, and burnt ochre. Other colours, which require to be used with greater precaution, are amel, or enamel blue, and cinnabar. Enamel blue must be applied instantaneously, and while the lime is very moist, otherwise it will not incorporate ; and if you retouch with it, you must do it an hour or more after the first applica- tion of it, in order to increase its lustre. Cinnabar has a splendour almost beyond all other colours, which it loses when mixed with lime. It may, however, be employed in places not exposed to the air, if carefully prepared. For this purpose, reduce a quantity of the purest cinnabar to pow- der, put it into an earthen vessel, and pour lime water on it two or three times. By this process the cinnabar receives some impression from the lime water, and you may then use it with greater safety. The white of lime is formed by mixing lime, slaked a long time before, with good water. The lime deposits a sediment in the vessel, when the water is poured off; this sediment is the white of lime. Ochres of all kinds make good colours for fresco, being previously burnt in iron boxes. Ultramarine never changes, and seems to communicate its permanent quality to the colours with which it is mixed. P A I P A I DICTIONARY OF MECHANICAL SCIENCE. ' 757 Distemper.—Until the discovery of oil-painting, the methods most generally adopted by all Italian painters were those of distemper and fresco. In distemper, when they painted on boards, they often pasted over the boards a piece of fine cloth, to prevent them from parting; they then laid on a layer of white, after which, having tempered their colours with water and paste, (or rather with water and yolks of eggs beat toge: ther with little fig-tree branches, the milk of which they mixed with the eggs,) they painted their picture with this mixture. All colours are proper for distemper, except the white of lime, which is used in fresco only. © ºn ſº a tº Oil Painting.—The principal advantage of oil painting over other methods, consists in the colours drying less speedily, so that it allows the painter to finish, smooth, and retouch his works with greater care and precision. The colours also being more blended together, produce more agreeable gradations, and a more delicate effect. tº g of Painting Flesh-Principal colours from which all the tints of the flesh are made, and their qualities in painting: Flake white is the best white known to us. This colour should be ground with the finest poppy, oil that can be procured. White comes forward to the eye with yellows and reds, but retires with blues and greens. It is the nature of all whites to sink into whatever ground they are laid on, therefore they should be laid on white grounds. Ivory black is the best black ; it is a colour which mixes kindly with all the others. It is the true shade for blue; and when mixed with a little Indian red, it is the best general shadow colour that can be used. It is gene- nerally ground with linseed oil, and used with drying oil. Black is a cold, retiring colour. Ultramarine is the finest blue in the world: it is a tender retiring colour, and never glares, and is a beautiful glazing colour. . It is used with poppy oil. ... Lake is a tender deep red, but of no strong body; therefore it should be strengthened with Indian red. . It is the best glazing colour that can be used. It is ground with linseed oil, and used with drying oil. Burnt umber is a fine warm brown, and a good working strong colour; it is of great use in the hair, and mixes finely with the warm shade. Process.-The process of oil painting, particularly in the co- louring of flesh and in landscape, is to be divided into three stages, or paintings. The colours and tints necessary for the first and second stages of painting flesh, are ; 1, flake, or fine white; 2, light ochre and its tints; 3, light red and its two tints; 4, vermilion and its tint; 5, a tint composed of lake, vermilion, and white; 6, rose tint; 7, blue tint; 8, lead tint; 9, green tint; 10, half shade tint, made of Indian red and white; 11, shade tint; 12, red shades; 13, warm shade. The finishing palette for a complexion requires 5 more : 1, carmine and its tint; 2, lake; 3, brown pink; 4, ivory black; 5, Prussian blue. First Stage, or Dead Colouring of Flesh.-The first lay of co- lours consists of two parts; the one is the work of the shadows only, and the other that of the lights. The work of the shadows is to make out all the drawing very correctly with the shade tint, in the same manner as if it was to be done with this colour only, and remember to drive or lay the colour sparingly. The lights should be all laid in with the light red tint, in different degrees, as we see them in nature. These two colours united, produce a clean, tender, middle tint. In uniting the lights and shades, you should use a long softener, about the size of a large swan quill, which will help to bring the work into character, and leave the colouring more delicate ; then go over the darkest shadows with the red or warm shade, which will finish the first day. The warm shade being laid on the shade tint, improves it to a warmer hue ; but if laid instead of the shade tints, it will dirty and spoil the colours it mixes with ; and if the red shade is laid first instead of the shade tint, the shadows would then appear too red; therefore, notwithstanding these two colours are the best that can be for the shadows, yet they are too strong to be laid alone, which is a proof of the great use and merit of the shade tint. Here we may observe, that the shade and light red tints are so friendly in their nature, than even in continually altering and changing, they always produce a clean colour of a pearly hue. Newt.—ln order to finish the first painting, improve the reds and yellows to the complexion, and after them the blues; ob- serving that the blues on the reds make the purple, and on the 78. r shades will appear. yellows produce the green. The same method is to be under- stood of the shadows; but be sure to leave them clean, and not too dark; therefore allowance should be made in the grounds with the light red, because ghazing them will make them darker. When the cloth is of a dark or bad colour, there must be a strong body of colour laid ałl over the shadows, such as will not sink into the ground, but appear warm, and a little lighter than the life, so that it may be of the same for- wardness to finish as if it had been a light ground ; therefore the business of dead-colouring is, that you leave it always in the same order for finishing, though the colour of the cloth is quite the reverse. Second, Painting, or Second Stage.—The second painting begins with laying on the least quantity that can be of poppy. oil; then wipe it almost all off, with a dry piece of a silk hand- kerchief. The second painting is also divided into two parts: one the first lay of the second painting ; which is scumbling the lights, and glazing the shadows; the other, finishing the comi- plexion with the virgin tints, and improving, as far as you can without daubing. * - First.—Scumbling is going over the lights where they are to be changed, with the light red tints or some other of their own colours, such as will always clear and improve the complexion, with short stiff pencils, but such parts only as require it, other. wise the beauty of the first painting will be spoiled. The light red tint improved is the best colour for scumbling and improv- ing the complexion in general. Where the shadows and drawing are to be corrected, you should do it with the shade tint, by driving the colour very stiff and bare, that you may the easier retouch and change it with the finishing tints. Some parts of the shadows should be glazed with some of the transparent sha- dow colours, such as will improve and come very near to the life; but be sure not to lay on too much of it, for fear of losing the hue of the first painting, the ground of which should always appear through the glazing. Be very careful, in uniting the lights and shades, that they do not mix dead and mealy; for the more the lights mix with the shades, the more mealy the Thus far the complexion is prepared and improved, in order to receive the virgin tints. Third Painting, or Finishing.—It is to be supposed the com- plexion now wants very little more than a few light touches; there- fore there will be no occasion for oiling. Begin with correcting all the glazing first, where the glazing serves as a ground or under part; then determine what should be done next, before you do it, so that you may be able to make the alteration on the apart with one stroke of the pencil. By this method you preserve both the glazing and the tints; but if it happens that you cannot lay such a variety of tints and finishing colours as you intended, it is much better to leave off while the work is safe and in good order; because those few touches, which would endanger the beauty of the colouring, may easily be done, if you have patience to stay till the colours are dry; and then, without oiling, add those finishings with free light strokes of the pencil. Of Painting Draperies.—The right method of painting dra- peries in general, is to make out the whole or the first lay with three colours only, viz. the lights, middle tint, and shade tint. In the first lay, the high lights should be laid with plenty of stiff co- lours and then shaped and softened into character with the mid- dle tint very correctly. Where the gradations of the lights are slow, as in the large parts, it will be proper to lay the middle tint first at their extremities, with a tool that will drive their colour, and leave it sparingly; because the lights will mix and lie the better upon it. Next make out all the parts of the sha- dows with the tint driven bare. After this comes the middle tint, for the several lights and gradations; which should be very nicely wrought up to character without touching any of the high lights which finish the first lay. The reflects and finish- ings tints are in general the antipathies of the first lays; they will, without great care, dirty the colours on which they are laid, and therefore shuld be laid with a delicate light touch, without softening. If it is overdone, endeavour to recover it with the colour of the part on which it was laid; this may be done directly, or when it is dry. Whether the reflects proceed from the same colour, or any other, the method of using them is the same. It often happens that the colour of the cloth is very 9 G. - 758 P A I P A I DICTIONARY OF MECHANICAL scIENCE. improper for the ground of the drapery; and when it is so, you should change it with those colours which are most proper to improve and support the finishing colours. • - . . White Satin.—All whites should be painted on white grounds, laid with a good body of colour, because this colour sinks more into the ground than any other. There are four degrees of co- lours in the first lay, to white satin. The first is the fine white for the lights; the second is the first tint, which is made of fine white and a little ivory black, mixed to an exact middle degree between the white and the middle tint. This colour follows the white, and it is with this you should shape the lights into character before you lay on any other: and take care that this first tint appears distinctly between the white and the middle tint, otherwise the beauty and the character of the satin will be spoiled. The middle tint should be made of white, black, and a little Indian red. These three colours are very friendly, and mix to a beautiful clear colour of a pearly hue, which has the true brightness and warmth of the general hue of the satin. Remember to allow for the red hue changing a little to the lead. We often see a little blue used in the first tint of white satin. - r ^ - - - Changeable Colours.-Changeable colours are made with four principal tints, viz. the high lights, middle tint, shade tint, and reflecting tint. The greatest art lies in finding the exact colour of the middle tint, because it has more of the general hue of the silk than any of the others. The shade tint is of the same hue with the middle tint, though it is dark enough for the sha- dows. The high lights, though often very different from the middle tint, should be of friendly-working colour, that will, in mixing with it, produce a tint of a clean hue. The method of painting silks is to make out the folds with the shade tint, and then fill them up in the lights with the middle tint. This first lay should be done to your satisfaction before you add any other colours; and the stiffer the middle tint is used, the better the high lights may be laid upon it. The reflecting tints fall generally upon the gradating harsh shades, and should be laid with tender touches sparingly, for fear of spoiling the first lay. This method of painting answers for all coloured silks, as well as changeable; with this difference only, that the plain colours require not so much art in matching the tints, as the change- able do. The last part of the work is the finishing and strength- ening the shadows with an obscure tint, a little inclining to a mellowish hue ; such as will not catch the eye, and interrupt the beauty of the lights. . . . * Black.-The best ground for black, is light red for the lights, an Indian red and a little black for the shadows. The finishing eolours are, for the lights, black, white, and a little lake. The middle tint has less white, and more lake and black: the shade tint is made of an equal quantity of lake and brown pink, with a very little black. The method of painting black is very dif- ferent from that of other colours; for as in these the principal thing is to leave their lights clear and brilliant; so in black, it is to keep the shadows clear and transparent. Therefore begin with the shade tint, and glaze over all the shadows with it. Next lay in the darkest shadows with black, and a little of the shade tint, very correctly. After that, fill up the whole breadth of lights with the middle tint only. All which should be done exactly to the character of the satin, velvet, cloth, &c. &c. and then finish with the high lights. Though the grounds mention- ed for the draperies are absolutely necessary for the principal and nearest figures in a picture, such as a single portrait, or the like ; yet for figures which are placed behind the principal or front figures, their ground should be always fainter in pro- portion to their local finishing colours. - - Linen.—The colours used in linen are the same as those in white satin, except the first tint, which is made of white and ultramarine ashes, instead of the black, and mixed to a very light bluish tint. º Of Painting Back Grounds.—The principal colours that are necessary for painting of back grounds, as walls, buildings, or the like, are white, black, Indian red, light and brown ochre, Prussian and burnt umber; from which the eight principal tints are made, as follows: 1. Pearl is made of black, white, and a little Indian red. 2. Lead, of black and white, mixed to a dark lead colour, 3. Yellow, of a brown ochre and white. 4. Olive, of light ochre; Prussian and white, 5. Flesh, of 3. Indian red and white, mixed to a little tint, 6. Murrey, of Indian red, white, and a little black, mixed to a kind of purple, of a middle tint. 7. Stone, of white, umber, black, and Indian red. , 8. Dark shade, or black and Indian red only. Here the lead tint serves for the blues, the flesh tint mixes agreeably with the lead, and the murrey is a very good blending colour, and of great use where the olive is too strong; the umber, white, and dark shade, will produce a fine variety of stone colours; the dark shade and umber, used plentifully with dry- ing oil, make an excellent warm shadow colour.. All the colours should be laid with drying oil only, because they mix and set the better with the softener. - , - , Process.-The process of painting back grounds is divided into two parts in stages: the first is the work of the first lay; the second that of the finishing tints. Begin the first lay from the shadowed side of the head, and paint the lights first; from them go into the gradations and shadows, which should be: done with a stiffish tool, very sparingly, with the dark shade and white, a little changed with the colours that will give it more of the required hue, but very near in regard to tone and the colours that join them. This do with the dark shade and strength, leaving them like mezzotinto. The dark and warm shadows should be laid before umber, driven with drying oil. If those colours were laid on first, they would spoil the transe parency, which is their greatest beauty. The more the first lay is driven, the easier and better you may change it with the finish- ing tints, therefore you may lay them with the greater body. The second part is to follow directly, whilst the first lay is wet, with those tints that are most proper to harmonize and finish with. Begin with the lights first, and remember, as you heighten and finish them, to do it with warmer colours; and let those be ac- companied with fine tender cold tints. The lightest parts of the ground should be painted with a variety of light warm clear colours, which vanish and lose their strength imperceptibly in. their gradations. Take care that you do not cover too much of the first lay, but consider it as the principal colour. From the lights go to the gradations and shadows: for when the lights are well adapted to produce and support the figure, it is easy to fall from them into whatever kind of shadows you find most proper; then soften and blend the whole with a long large hog-tool; which, with the strength and body of the drying oil, will melt and sweeten altogether, in such a manner as will seem surprisingly finished. Remember the tints will sink, and lose a little of their strength and beauty in drying. All grounds, as walls, &c. should be finished at one painting ; but if they want to be changed, glaze them with a little of the dark shade and drying oil, driven very bare; on which with a few light touches of the colour that is wanting, you may improve their hue. The dark shadows may also be strengthened and improved by glaz- ing, which should be done after the figures are nearly finished, for fear of making them too strong. Curtains should be dead- coloured when we paint the ground ; and should be done with clean colours, of a near hue to the intended curtain, such as will support the finishing colours; do it with a tender sort of keeping, and near in regard to their tone in the lights, but much softer in the shadows; all which should be mixed and broken with the colours of the ground. It will often happen, that we cannot make the folds the first painting; we should then leave the masses of light and shadow, in regard to the keeping of the picture, broad and well united together, such as may seem easy to finish on. The colours of the landscapes in back grounds, should be broke and softened also with those of the parts which join them. This method will make all the parts of the ground as it were of one piece. The sky should be broke with the lead and the flesh tints. The murrey tint is of great use in the grounds of distant objects; and the umber and dark shades, in the near grounds. The greens should be more beau- tiful than you intend them, because they will fade and grow darker. After all is painted, go over the whole very lightly with the softener, as you did the grounds, which will make it look agreeably finished. - Of Painting Landscapes.—The principal colours used in land- scapes are, i. Flake white; 2. White lead or common white; 3. Fine light ochre; 4. Brown ochre; 5. Brown pink; 6. Burnt umber; 7. Ivory black; 8. Prussian blue ; 9. Ultramarine; 10. Terreverte; 11. Lake; 12. Indian red; 13. Vermilion, or P A I P A I DICTIONARY OF MECHANICAL SCIENCE. 759 native cinnabar; 14. King's yellow. The principal tints are, 1. Light ochre, and white; 2. Light ochre, Prussian blue, and white; 3. Light ochre and Prussian blue; 4. The same darker; 5. Terreverte and Prussian blue; 6. Brown pink and Prussian blue; 7. Brown link and brown ochre; 8. Brown pink, ochre, and Prussian blue; 9. Indian red and white; 10. Ivory black, Indian red, and lake. The colours necessary for dead colour- ing are: common white, light ochre, brown ochre, burnt umber, Indian red, ivory black, and Prussian blue. The principal co- lours and tints for painting the sky are, fine white, ultramarine, Prussian blue, light ochre, vermilion, lake, and Indian red. The tints are, a fine azure, lighter azure, light ochre, and white vermilion and white; and a tint made of white, a little vermi- lion, and some of the light azure at your discretion. Proeess.-Sketch or rub in your design faintly, with burnt umber used with drying oil, and a little oil of turpentine, leav- ing the colour of the cloth for the lights. Remember, in doing this, to leave no part of the shadows so dark as you intend the first lay or dead colouring, which also is to be lighter than the finishing colours. Though the foliage of the trees is only rub- bed in faintly, yet the trunks and bodies should be in their pro- per shapes, with their breadths of light and shadows. All kind of buildings should be done in the same manner, leaving the colour of the cloth for their lights. The figure on the fore ground may also be sketched in the same manner, and then left to dry. - First Painting, or Dead Colouring.—Let the first lay or dead colouring be without any bright, glaring, or strong dark co- lours; so that the effect is made more to receive and preserve the finishing colours, than to shew them in their first painting. The sky should be done first, then all the distances; and so work downwards to the middle group, and from that to the fore ground, and nearest parts. Remember, all the parts of each group, as trees, buildings, or the like, are all painted with the group they belong to. The greatest secret in dead colour- ing is to find the two colours which serve for the ground of sha- dows in general, the sky excepted; and the method of using them with the lights, the first of which is the dark shade with a little lake in it; the other colour is only burnt umber. These should be a little changed to the natural hue of the objects, and then laid on with drying oil in the same manner as we shade with Indian ink, which is a kind of glazing, and as such they should be left, otherwise they will be dark and heavy; and there- fore would be entirely spoiled for the finishing glazing. Both these colours mix and sympathize agreeably with all the lights, but should be laid before them. The Sky.—The sky should be laid with a good body of colours and left with a faint resemblance of the principal clouds, more . in the manner of claro-obscure than with finishing colours; the whiter it is left, the better it will bear out and support them ; the distances should be made out faint and obscurely, with the dark shades and some of their lights in different degrees, and laid so as best to find and shew their principal parts. All the grounds of the trees should be laid or rubbed in, enough only to leave an idea of their shapes and shadows faintly. The ground of their shadows must be clean, and lighter than their finishing colours. In painting the lights, it is better to incline more to the middle tint, than to the very high lights; and observe to leave them with a sufficient body of clean colours, which will preserve the finishing colours better; all which may be done with a few tints. After this, go over the whole with a sweetener very lightly, which will soften and mix the colours agreeably for finishing. - Second Painting.—Begin with the sky, and lay in all the azure, and colours of the horizon; then soften them ; after that lay in the general tint of the clouds, and finish on it with the high lights and the other tints that are wanting, with light tender touches; then soften the whole with a sweetener very lightly. The finishing of the sky should be done all at one painting, be- cause the tender character of the clouds will not do so well as when the whole is wet. Observe, that the stiffer the azure and colours of the horizon are laid, the better the clouds may be painted upon them. º Third and last Painting.—If oiling is necessary, lay the least quantity that can be ; which should be done with a stump tool or pencil, proportioned to the place that is to be oiled, so as to draperies. oil no more than is wanted: then wipe the whole place that is oiled, with a piece of silk handkerchief. When going to finish any objects, remember to use a great variety of tints, very nearly of the same colour, but most of all when finishing trees. This gives a richness to the colouring, and produces harmony. The greens will fade, and grow darker; therefore it is highly necessary to improve and force them, by exaggerating the lights, and making an allowance in using them so much the lighter. For the same reason, take great care not to over- charge and spoil the beauty of the glazing ; for if you do, it will be dull and heavy, and will consequently grow darker. The method of painting near trees is, to make the first lay very near to nature, though not quite so dark, but more in the degree of a middle tint, and follow it with strengthening the shadows; then the middle tints; and last of all lay the high lights and finishing colours. All this cannot be done as it should be, at one painting ; therefore the best way is, to do no more than the first lay with the faint shadows, and leave it to dry. Then begin with improving the middle tints and shadows, and let them dry. The third and last work is, adding all the lights and finishing colours in the best manner you are able. This method of leaving the first and second parts to dry sepa- rately, not only makes the whole much easier, and more agree- able, but leaves the colours in the greatest perfection; because most of the work may be done with scumbling and glazing, and some parts without oiling. The lights also may be laid with a better body of colour, which will not be mixed and spoiled with the wet ground. The figures in the landscapes are the last work of the picture; those in the fore-ground should be done first, and those in the distances should be done next ; for after the figures in the first and farthest group are painted, it will be much easier to find the proportions of those in the middle parts of the picture. And observe, that the sha- dows of the figures should be of the same hue, or colour, with those of the group or place they are in. r Qualities of the above Colours when used in Miniature.— Yellows. Gall-stone is one of the finest and brightest colours, and a lasting one : but it should be sparingly used in the flesh tints, its brilliancy being apt to overpower all the other colours. Terra Sienna is a bright yellow earth, somewhat of a greasy nature, and is used as a warm yellow ; but when burnt, is more beautiful, partaking of three tints, yellow, red, and brown. Nottingham ochre works well, but on account of its heavy qualities must be used with caution. Roman ochre is used with success in miniature painting, as it works, wºn properly proportioned with gum water, extremely sharp and meat; and being in itself a warm colour, communicates that quality to the tints it is worked in. Naples yellow, although adopted by some artists, is of a sickly hue, and has this very bad quality, that it absorbs all colours that are either worked on it, or mixed with it. - 4 - Blues. Ultramarine excels all others in permanency. Prus- sian blue has no substitute, on account of its strength of effect and transparency. Smalt is so hard that nothing but an agate flag and muller will pulverize it sufficiently. It is not to be depended on for permanency. Indigo is a useful blue, though it must be sparingly used, on account of its extreme depth of colour, nearly approaching to black; the best is called the rock indigo. The way to judge of its qualities is to break it, and, if good, it will have a copperish hue, but if bad, it will be of a dead blackish cast. Chinese vermilion, when good, is a bright red, and useful in miniature pictures, though not to be freely used, its opacity rendering it dangerous to mix much with other colours; but by itself, in touching the parts that require extreme brightness, it is of wonderful service. It is very diffi- cult to find the real kind—the common vermilion, mixed with lake or carmine, being a general substitute; but the spurious and the genuine kind very materially differ in working, the for- mer being thick and heavy, the other the contrary. India red is an excellent colour, not only for touching the deep red parts, but likewise in strong flesh tints, in bright back-grounds, and Browns. Umber is very greasy, and mixes unkindly; but, when burnt, is very useful in many parts of miniature. Terra de Cassel, or Vandyck brown, so called from the very great estimation the inimitable painter of that name held it in, is the 760 P A I P A I BICTion ARY OF MECHANICAL scIENCE. first rich brown in the world; in itself producing a more beau- tiful colour than can be formed by the junction of any colours whatever, - - - - * - * Ivory.--Qf ivory there are various kinds, the distinction of which in this art is of very material consequence. Ivory, newly cut, and full of sap, is not easily to be judged of; the general transparency it exhibits in that state, almost precluding the possibility of discovering whether it is coarse-grained or fine, streaky or the contrary, unless to the artist who, by a long course of experience, is familiarized to it. The best way to discover the quality of it is, by holding it grainways to the light, then holding it up and looking through it, still turning it from side to side, and very narrowly observing whether there are any streaks in it; this you will, unless the ivory is very freshly cut, easily discover: and in this you cannot be too particular. . There is a species of ivory which is very bad for painting on, although it has no streaks in it, being of a horny -coarse nature, which will never suffer the colours to be thrown out in the brilliant manner a fine species of ivory will; you are, therefore, not only to be cautious in choosing ivory free from streaks, but likewise that which has the finest grain, and close. —Having instructed in the mode of choosing ivory, and having prepared it for painting on, we now proceed to give— Instructions for Mixing Compound Tints for the Face.—Purple is formed of either ultramarine, Prussian blue, smalt, or indigo, mixed with either carmine or drop lake. Ultramarine, although the most beautiful and brilliant of colours by itself, yet in any mixture it loses that perfection, but still retains a sufficient share of brightness to render it a desirable tint in the purplish gray shadows of the face. Prussian blue, mixed as before- mentioned, makes a bright or dark purple, according as the quantities of either colours are proportioned; but indigo makes still darker, owing to its great natural depth of colour. Smalt and carmine, or lake, form nearly the same tint as ultramarine, and may be used nearly for the same purposes. * Gray. Of gray tints there are various kinds, according to the subjects they are required for. A warm gray tint may be made by duly portioning burnt terra Sienna, Prussian blue, and drop lake; the more terra Sienna in it, the warmer the tint; the more Prussian blue and lake, the colder. Another. gray tint, used with success by some eminent miniature pain- ters, was composed of Prussian blue and Chinese vermilion, | but on account of the unkind manner with which vermilion in- corporates with any other colour, it required a greater propor- | tion of gum than ordinary to make them work or keep together. A third gray tint, which is an excellent one, is formed of ºp lake, sap-green, and Prussian blue. Olive Tints. A very fine olive tint is formed of gall-stone, Nottingham ochre, and carmine, or lake; and another of sap- | green and lake simply. Of Colours proper for Men's head, make some general observations; the first of which is, that in all cloth draperies for men's portraits, it is necessary to add some ſlake white; as it not only gives the colour the dead appearance which cloth exhibits, but likewise its being incor- porated with the flake white, gives it a body which makes the flesh tints appear to more advantage. The next observation is, that in grinding up your draperies, you are to make them ap- pear several degrees lighter in colour than you want them to be when dry—for this reason; the flake white is a colour so very heavy, that, after you float in your coat, it will sink to the bot- tom, and leave your colours several degrees darker than when it was wet; and finally you are not to be too heavy or thick in floating in your draperies, but merely to see that your colour is evenly spread over the part. Black drapery is formed of lamp black burnt, and flake white; and must be laid in with a good deal of the latter, as otherwise it will be very difficult to imanage the shadows so as to produce a pleasing effect. Scar- let is a colour very difficult to lay down rules for making, as in some pictures it is dangerous to make it too bright, for fear of hurting the effect of the face by its brilliancy catching the eye too readily; consequently, if the subject you are painting from life is very pale, you run a very great risk by annexing a very bright scarlet to his picture. We shall therefore only mention that a very bright scarlet is made of Chinese vermilion and carmine, ground together, (without any flake and white;), and if you want it still rendered brighter when it is dry, fill your pencil with plain carmine, mixed with thin gum-water, and glaze over it micely ; but if, on the contrary, you wish to sadden, or take away a share of its brilliancy, add a little.flake white to it, and that will have the desired effect. t . List of several of the most eminent Painters of the Old School, with a Scale of their different Merits, so far as regards Compo- sition, Design, Colouring, and Eapressioh. g * # | School. | Fº Name. Date of Birth and Death. | Albano, born 1578, died 1660, ........ Albert Durer, born 1470, died 1528, .. Andrea del Sarte, born 1478, died 1530, Baroche, born 1528, died 1612, . . . James Bassau, born 1553, died 1613, ... 6|| 8 John Bellin, born 1421, died 1501, . . . . . 4|| 6 l 4 Lombard, ... Flemish, . . . . Roman and Florentine, ; Roman, . . . . Venetian, ... Venetian, . . . . 8 I 0 12 1. 5 6 l Draperies.—We shall, under this French, . . . . French, . . . . French, . . . . Lombard, . . . . Lombard, .... Roman, . . . . . Flemish, . . . . Lombard, . . . Venetian, ... Lombard, . . . Flemish, . . . . Flemish, . . . . Flemish,. . . . Roman, ... . . Lombard, ... Roman, . . . . . Flemish, ... . Roman, . . . Lombard, ... Venetian, ... Flemish, .. Venetian, ... Venetian, ... Roman, .. dº e e' tº 4. . Venetian, .... Roman, . . . . . Roman, Roman, • e o 'º e” tº ſº e º e Roman, .. Venetian,.... French, ... . . . Roman, Roman, ... . . Tlemish, ... . Flemish, . . . . Roman, ... . . French, ..... Tlemish,.... Roman, ... . . Venetian, ...: Venetian, .... Flemish, .... Roman, ..... Roman, a e s a e , * † tº g º Bourdon, born 1513, died 1588, . . . . . . . Le Brun, born 1620, died 1690, . . . . . . . Claude Lorraine, born 1600, died 1682, Annibal Carracci, born 1557, died 1606, Correggio, born 1494, died 1534, . . . . . . . . Daniel de Volterra, born 1509, died 1556, Diepembeck, born 1608, . . . Dominechino, born 1581, died 1641, . . . . Georgioni, born 1477, died 1511,. Guido, born 1575, died 1642, . . . . . . tº a Holbein, born 1498, died 1544, ... . . . . . James Jordans, born 1594, died 1678, .. Lucio Jordano, born 1632, died 1705, .. Julio Romano, born 1446, died 1500,... Lanfranc, born 1581, died 1647, . . . . . . . Leonardo da Vinci, born 1445, died 1520, Lucas de Leide, born 1495, died 1535, Michael Angelo Buonarotti, born 1474, \ | died 1564, . . . . . . . . Michael Angelo Caravaggio, . . . . . . . . . . Muticus, born 1528, died 1590, . . . . . . . . Otho Venius, born 1556, died 1634,.... Palma, the elder, born 1460, died 1556, Palma, the younger, born 1544, died 1628, Parmesan, . . . . . . . . . . . . . . . . . . . . . . . . . Paul Veronese, born 1532, died 1588, . . Perin del Vague, born 1500, died 1547, Pietro de Cortona, born 1596, died 1669, Pietro Perugino, born 1524, died 1602, Polidore de Caravaggio, born 1596, died 1643, ... . . . . . . . . . . . : s e º 'º e •. Pordenon, e e. g. g º º ſº e º 'º g a tº tº * e s e o e . * * * * * Nicholas Poussin, born 1594, died 1665, Primatrice, died 1570, . . . . . . . . . . . . . . Raphael, born 1483, died 1520, ... . . . . . Rembrandt, born 1606, died 1668, . . . . Rubens, born 1577, died 1640, . . . . . . . . Salviati, born 1510, died 1563, . . . . . . . . Le Sueur, born 1617, died 1655, . . . . . . Teniers, born 1582, died 1649, . . . . . . . . Pietro Testo, born 1611, died 1650, . . . . Tintoretto, born 1512, died 1594, . . . . . . Titian, born 1477, died 1576, . . . . . . . . . Vandyck, born 1599, died 1641, ...... Vanius, born 1556, died 1634, . . . . . . . tº . Tadee Zucree, born 1529, died 1556, . . 15 15 17 18 13 15 I5 11. 15. 12 15 13 13 15|| 16| 14 12 17 14 17| 14 18 6 13| 15 15 || 12: 15 164: 154 IU 15. 14 17 12 | 0 || 1 1 I l l: Ii 5 - Description of a Rest for the Use of Painters, by Wm. Brocke- don, Esq.-The painter's-rest is intended as a substitute for the common maul-stick, the inconvenience of which has been . often felt by painters; sometimes from its increasing the pres- sure, to the fatigue of the hand, which also supports the pallet; often, in spite of the padding with which the end is armed, doing injury to the picture, if not quite dry. These disadvan- tages are obviated by the following machine; which consists P A L P A L DICTIONARY OF MECHANICAL SCIENCE. 761 of a frame, with feet of unequal length, the longest being always placed under the easel,that the pressure of the hand may not turn it over towards the picture. In the outer frame of the rest, a sliding frame is māde to rise, and be fixed by a ratchet: if the height required exceed the extent of the ratchet, the swing frame will again extend the elevation, owing to its pivots -being placed out of the centre. The machine is capable of any adjustment, from the low sitting elevation of an invalid to a very high standing one, and it is firm enough to steady the hand perfectly. + . . - This figure is a perspec- tive view of the rest; p p, two standards, framed toge- ther near the foot-board by a cross bar, and by the bar z at the top; q, a rack, cut in the right-hand one; r, the click, catching in it; s, s, two other standards, framed together only by the bars t and v, having rabbets along their outsides, fitting into grooves in the inside of the standards pp, which serve as guides to them when slid- ing up and down. The frame s's is supported at any re- quired height by the clickr ; u u, a long frame, filling the space between the stand- ards ss; it is fixed to these latter by the thumb-screws w w. The upper part of this frame forms the rest for the arm; and, in order to pre- vent it from turning on the screws w w, a pin or bolt ac, pushes in, to fix it : it has a loop-hole, through which a smaller pin passes, to keep º/ it to its place. By with- - drawing the little pin ac, the frame w w may be turned round on the screws w w, and secured by them and by the bolt, as shewn by the dotted lines, to give an additional elevation; the same rack q giving the intermediate height between this position and the former. The left-hand figure shews a bird’s-eye view of one foot y y, and standards p and s, and part of the frame w. The painter gives additional steadi- mess to the rest, by putting one foot on the foot-board y y in front. The whole rest inclines, from top to bottom, about as much as an easel in use generally does, and the long feet go under the canvass, to let it approach near enough. PAKFONG, orWHITE Copper, a metal composed of copper, nickel, and zinc. The zinc amounts to nearly one half of the whole, and the proportions of copper and nickel are as 5 to 13. This compound metal is much used among the Chinese. PALAESTRA, in Grecian Antiquity, a public building, where the youth exercised themselves, in wrestling, running, playing at quoits, &c. PALAMEDEA, a genus of birds, belonging to the order of grallae. The character of this genus is, the bill bends down at the point with a horn, or with a tuft of feathers erect near the base of it: the nostrils are oval; the toes are divided almost to their origin, with a small membrane between the bottoms of each. PALATE, in Anatomy, the flesh that composes the roof, or the upper and inner part, of the mouth. e FALATIN E Counties of England, are Chester, Durham, and Lancaster, the owners of which, the Earl of Chester, the Bishop of Durham, and the Duke of Lancaster, can, or may, or could, pardon treasons, murders, and felonies, appoint their own judges, justices, and issue writs and indictments, as the king can in the other counties that are not palatinate. - PALILICUM, another name for the star Aldebaran. PALING, in Agriculture, a kind of fence-work for fruit º It is also a fence made by stakes being driven into the ground. - Zº 3/ PALISADES, stakes made of strong split wood, used in fortification, and for the support or defence of embankments. PALISSE, in Heraldry, a bearing like a range of palisades before a fortification, represented on a fosse, rising up a con- siderable height and pointed at top, with the field appearing before them. - - PALLADIUM. This is a new metal first found by Dr. Wol- laston associated with platina, among the grains of which he supposes its ore to exist, or an alloy of it with irridium and osmium, scarcely distinguishable from the crude platina, though it is hardier and heavier. Palladium is of a greyish white co- lour, scarcely distinguishable from platina, and takes a good polish. It is ductile, and very malleable ; and being reduced into thin slips, is flexible, but not very elastic. Its fracture is fibrous and in diverging striae, shewing a kind of crystalline arrangement. In hardness it is superior to wrought iron. Its specific gravity is from 109 to 11.8. - PALLADIUM, a statue of Minerva, which the Trojans imagined fell from heaven, and that their city could not be taken whilst that remained in it. - PALLAS, one of the new planets discovered by Dr. Olbers, March 28, 1802. It is situated between the orbits of Mars and Jupiter, and is nearly of the same magnitude with Ceres, but of a less ruddy colour. It is surronnded with a nebulosity of less extent, and performs its annual revolution in nearly the same period. The planet Pallas, however, is distinguished in a very remarkable manner from Ceres and all other primary planets, by the immense inclination of its orbit. While these bodies are revolving round the sun in almost circular paths, rising only a few degrees above the plane of the ecliptic, Pallas ascends above this plane at an angle of about thirty-five degs., which is nearly five times greater than the inclination of Mer- cury. From the eccentricity of Pallas being greater than that of Ceres, or from a difference of position in the line of their apsides, while their mean distances are nearly equal, the orbits of these two planets mutually intersect each other; a pheno- menon which is altogether anomalous in the solar system. PALLET, among Painters, a little oval table or piece of wood, or ivory, very thin and smooth; on and round which the paint- ers place the several colours they have occasion for, to be rea- dy for the pencil. The middle serves to mix the colours on, and to make the tints required in the work. It has no handle, but instead thereof a hole at one end to put the thumb through to hold it. * PALLET, among Potters, crucible makers, &c., a wooden in- jº. almost the only one they use for forming, beating, an nding their works: they have several kinds; the largest are oval, with a handle; others are round, or hollowed trian- gularly ; others, in fine, are in manner of large knives, serv- ing to cut off whatever is superfluous on the moulds of their work. PALLeT, in Gilding, an instrument made of a squirrel's tail, to take up the gold leaves from the pillow, and to apply and extend them on the matter to be gilt. - PALLIUM, or PAll, an archiepiscopal vestment of white woollen cloth, about the breadth of a border, made round, and thrown over the shoulders: upon this border there are two others of the same matter and form, one of which falls down upon the breast and the other upon the back, each having a red cross upon it; several crosses of the same colour being likewise upon the upper part of it about the shoulders. The pall was part of the imperial habit, and originally granted by the emperors to patriarchs, but at present it is given by the pope as a mark of the apostolic power, without which neither the function nor title of archbishop can be assumed by the bishops of his com- munion. ** PALM, an ancient long measure taken from the extent of the hand. The Roman palm was of two kinds; the great palm, taken from the length of the hand, answered to our span, and contained twelve digits, or fingers’ breadths, or nine Roman inches, equal to about eight and a half English inches. The small palm, from the breadth of the hand, contained four digits | or fingers, equal to about three English inches. The Greek palm, or dorón, was also of two kinds; the small contained four fingers, equal to little more than three inches; the great | palm contained five fingers. The Greek double palm, called 9 H fº P A P 762 P A P DICTIONARY OF MECHANICAL | SCIENCE, dichas, contained also in proportion. The modern palm is different in different places, where it is used. It contains Inc. Lines. * At Rome . . . . . . . . . . . . . . . . . . * * * * * * * * * * * * * *... • *... • * * * * * * 3} - At Naples, according to Riccioli . . . . . . . . . . . . . . . . . . . . . . . . 8 0 Ditto, according to others . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 7 At Genoa. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 9 At Morocco and Fez. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2 Languedoc, and some other parts of France . . . . . . . . . . . . . . . . 9 9 The English palm is. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 0. PALMAE, Palms, comprehend several genera of plants, with simple stems, which at their summits bear leaves resembling those of ferns, being a composition of leaf and branch. PAN ACEA, among Physicians, denotes an universal medi- cine, or a remedy for all diseases. PANAX, (Gin-Seng,) a genus of plants belonging to the polygamia class, of which there are nine species. PANCREATIC JUICE, a liquid secreted by the pancreas, which is found to be analogous to saliva, and probably serves the same purpose in promoting the digestion of the food. PANDECT.S, or PANDECTRE, in Jurisprudence, are 50 books of Roman civil law, abridged by Justinian's order; though Papias extends the signification of this word to the books of the Old and New Testament. The original copy (supposed to be) is in the possession of the Medici family at Florence. The pandects of Justinian sufficiently shew how zealously the lawyers and advocates of passive obedience laboured in the cause of prerogative. - - PANEL, a schedule or roll of such jurors as the sheriff returns to pass upon any trial ; and impanelling a jury, is returning their names in such schedule of parchment. In Scots law, the prisoner at the bar is the panel. - PANEL, in Joinery, is a tympanum, or square piece of thin wood, sometimes carved, framed or grooved in a larger piece between two upright pieces and two cross pieces. PANIC, denotes an ill-grounded terror or fright. The origin of the phrase is from Pan, one of the captains of Bacchus, who with a few men put a numerous army to rout, by a noise which his soldiers raised in a rockey valley favoured with a great number of echos: for this stratagem making their numbers ap- pear much greater than it really was, the enemy quitted a very commodious encampment, and fled. , Hence, all ill-grounded fears, have been called panics, or panic fears. PANICUM, a genus of plants belonging to the triandria class. PANICUM Miliaceum. Millet.—Millet is of two kinds, the brown and yellow. They are sometimes sown in this comatry for feeding poultry, and also for dressing ; i. e. it is dive Of the husk by being passed through a mill, when it is equal to rice for the use of the pastry cook. The seed used is from one to two bushels per acre. This is very commonly grown in Italy, and on the shores of the Mediterranean sea, from which large quantities are annually exported to the more northern countries. # PANTHER. See FELIS. * PAPAVER, the Poppy, a genus of the monogymia order, in the polyandria class of plants; and in the natural method rank- ing under the 27th order, rhoeaedae. The corolla is tetrapetalous, the calyx diphyllous, the capsule bilocular, opening at the pores below a persisting stigma. There are nine species: 1. The somniferum, or somniferous common garden poppy. There are of this a great many varieties, some of them extremely beautiful. The white officinal poppy is one of the varieties of this sort. It grows often to the height of five or six feet, having large flowers both single and double, succeeded by capsules or heads as large as oranges, each containing about 8000 seeds. PAPER, WRITING, is, in Europe, manufactured from linen rags chiefly. These rags are first cut or chopped, then dusted, and reduced to pulp in mills, by cylinders, &c. The workman now immerses into the pulp vat a mould composed of wire cloth, and furnished with a frame to retain the stuff. He then draws out as much of this pulp as is necessary for one sheet, over which he places a felt, to absorb the moisture; and thus a felt and sheet of paper are placed alternately, till he has formed six quires of paper. When the last sheet is covered with felt, the whole is pressed, and the sheets are Suspended on cords to dry. The next operation is sizing, which is performed by plunging the paper into a vessel of size, containing a small portion of alum. The paper is then dried, and folded into quires of 24 sheets, and finally made up into reams containing 20 quires each. - - Blotting paper, drawing, engraving, and printing paper, are prepared much in the same way, but they are not so highly sized. In lieu of rags, barley straw is employed in the manu- facture of paper, but it will only serve for common purposes, as it communicates an unpleasant tinge. | * To make Stained Paper. This is done by applying, by soft brushes, any of the colours used for tinging other substances, after tempering them properly with size or gum water. If the paper is to be of a uniform colour, it must be fixed by several thin coatings, each being suffered to dry before another is applied; otherwise the shade will appear clouded. Marbled Paper, is a sort of paper variously stained, or painted as it were with divers colours; made by applying a sheet on the surface of a liquor, wherein colours, diluted with oil or ox's gall, are suspended. The manner of making it is thus:–A trough is provided of the shape and dimensions of a sheet of the paper to be marbled, and about four fingers deep; this is made of lead or wood well joined, and pitched or primed to contain the liquor. For the liquor, a quarter of a pound of gum tragacanth is macerated four or five days in fair water; this they stir from time to time, and add to it daily fresh water, till it be of a consistency somewhat thinner than oil; then they strain it into the trough. The colours to be applied thereon, for blue, are, indigo ground up with white lead, or Prussian blue and verditer may be used: for green, indigo and orpiment, the one ground and the other tempered, mixed and boiled toge- ther with common water; or verdigris, a mixture of Dutch pink and Prussian blue, or verditer, in different proportions: for yellow, orpiment bruised and tempered; or Dutch pink and yellow ochre: for red, the finest lake, ground with raspings of Brasil wood, which has been prepared by boiling half a day; or carmine, rose pink, vermilion, and red lead; the two latter of which should be mixed with rose pink or lake, to bring them to a softer cast: for orange, orange lake, or a mixture of ver- milion, or red lead, with Dutch pink: for purple, rose pink and Prussian blue. Into all these colours, properly ground with spirit of wine, they put a little ox or fish gall, which is two or three days old; and if the colours dilate not of themselves sufi- ciently, they add more gall; on the contrary, if they spread too much, the gall is over-dosed, and must be corrected by adding more of the colour without gall. For the operation of marbling, when the gum is well settled in the trough, they extend a sheet of paper, and plunge it very shallow into the liquor, suddenly lifting it out again, in order to stir up and raise the subsiding gum towards the surface, and for the more universal impregnating of the liquor. This done, and all the colours ranged in gallipots on the table, where also the trough is placed, they begin by dipping a brush of hog's hair into any colour, commonly the blue first, and sprinkle it on the surface of the liquor: if the colour has been rightly prepared, it will dilate itself duly therein. This done, the red is applied in the like manner, but with another pencil; after this, the yellow ; lastly, the green. For white, it is made by only Sprinkling fair water, mixed with ox’s gall, over the liquor. When all colours are thus floating on the liquor, to give them that agreeable cambletting, which we admire in marble paper, they use a pointed stick; which being applied by drawing it from one side of the trough to the other, with address, stirs up the liquor and fluctuating colours; then with a comb, made of wood, about five inches long, with brass teeth, about two inches in length, and a quarter of an inch distant from each other, taken by the head with both hands, they comb the surface of the liquor in the trough, from one extreme to another, permit- ting only the teeth to enter; this being performed with a gentle and uniform motion, makes those clouds and undula- tions on which the beauty of the paper depends. If it be far- ther desired to have the colours lie in any other fantastical pos- ture, representing serpents, or the like, it is effected with the pointed.stick above mentioned, by drawing it over what has been already combed; but this must be done with a dexterous hand, and with a shallow dip into the liquor, circling, as if you would draw some flourish, or figured letter. Lastly, the P A P. P A P DICTIONARY OF MECHANICAL SCIENCE. 763 colours being in this posture, the operator displays and applies on them a sheet of white moistened paper; to do which, artist- like, requires a sleight only to be obtained by practice; because the surfaces of the liquor and the paper are to meet equally in all parts; which done, before the colours have time to soak through, which, unless the paper be very thick, will be in the space of two or three pulses, he lifts up the paper nimbly, and with an even hand; and then, after spreading it a while on a board, hangs it on a line to dry; which, when sufficiently done, they first rub it with a little soap, and then polish it with a marble stone, ivory knob, or glass polishers; or with a burnisher of jasper or agate. It must be observed, that the sprinkling of the colours is to be renewed, and all the other ceremonies performed with the stick and comb, at every application of fresh paper, by reason that every paper takes off all the colour from the liquor. Rice Paper, is a curious sort of paper, made by the Chinese; it is semi-transparent, of a firm texture, and feels somewhat like the article manufactured from the papyrus. The Chinese : also make paper from the rind or bark of the mulberry tree, the elm, the bamboo, and cotton tree. In fact, every diſſerent province has its own provincial paper. The second skin of the bamboo bark is peculiarly soft and white. This they beat in fair water into a pulp, which they take up in large moulds, so that some sheets are above twelve feet in length. They are completed by dipping them in alum water, which serves in place of our size. Each province not only manufactures a paper peculiar to itself, but stains it pink, green, or straw colour, as their fathers from time immemorial have done. Ivory Paper. The properties which render ivory so desir- able a subject for the miniature painter, and other artists, are, the evenness and fineness of its grain, its allowing all water colours laid on its surface to be washed out with a soft wet brush, and the facility with which the artist may scrape off the colour from any particular part, by the point of a knife, or other convenient instrument, and thus heighten and add bril- liancy to the lights in his painting more expeditiously and effi- caciously than can be done in any other way. The high price of ivory, the impossibility of obtaining plates exceeding very moderate dimensions, and the coarseness of grain in the larger of these, and its liability, when thin, to warp by changes of the weather, together with its property of turning yellow by long exposure to the light, owing to the oil which it contains, render some substitute very desirable. The ivory paper we are now about to describe, admits of traces being made on the surface by a hard black lead pencil; which are much easier effaced by Indian rubber than from common drawing paper; and this cir- cumstance, with the extremely fine lines which its hard and even surface is capable of receiving, peculiarly adapts it for the reception of the most delicate pencil drawings and out- lines. The colours laid upon it have a greater brilliancy than when laid upon ivory, owing to the superior whiteness of the ground. The following is the process given by Mr. Einslie, of Stratton Ground, Westminster, to the Society of Arts, for which he was voted the sum of thirty guineas:—Take a quar- ter of a pound of clean parchment cuttings, and put them into a two-quart pan, with nearly as much water as it will hold; boil the mixture gently for four or five hours, adding water from time to time, to supply the place of that driven off by evapora- tion; then carefully strain the liquor from the dregs through a cloth, and when cold it will form a strong jelly, which may be called size No. 1. Return the dregs of the preceding process into the pan, fill it with water, and again boil it as before for four or five hours; then strain off the liquor, and call it size No. 2. Take three sheets of drawing paper, (outsides will answer the purpose perfectly well, and being much cheaper, are therefore to be preferred,) wet them on both sides with a soft sponge dipped in water, and paste them together with the size No. 2. While they are still wet, lay them on a table, and place them upon a smooth slab of writing slate, of a size some- what smaller than the paper. Turn up the edges of the paper, and paste them on the back of the slate, and then allow the paper to dry gradually. Wet, as before, three more sheets of the same kind of paper, and paste them on the others, one at a time; cut off with a knife what projects beyond the edges of the slate, and when the whole has become perfectly dry, wrap a . small piece of slate in coarse sand paper, and with this rubber make the surface of the paper quite even, and smooth. ...Then paste on an inside sheet, which must be quite free from spots or dirt of any kind; cut off the projecting edges as before, and when dry, rub it with fine glass paper, which will produce a perfectly smooth surface. Now, take half a pint of the size No. 1, melt it by a gentle heat, and then stir it into three table- Spoons full of fine plaster of Paris; when the mixture is com- pleted, pour it out on the paper, and with a soft wet sponge distribute it as evenly as possible over the surface. Then allow the surface to dry slowly, and rub it again with -fine glass paper. , Lastly, take a few spoons full of the size No. 1, and mix it with three-fourths its quantity of water; unite the two by a gentle heat, and when the mass has cooled, so as to be in a semi-gelatinous state, pour about one-third of it on the surface of the paper, and spread it evenly with the sponge; when this has dried, pour on another portion, and afterwards the remainder; when the whole has again become dry, rub it over lightly with fine glass paper, and the process is completed; it may, accordingly, be cut away from the slab of slate, and is ready for use.—The quantity of ingredients abovementioned is sufficient for a piece of paper 174 by 15% inches. Plaster of Paris gives a perfectly white surface; oxide of zinc, mixed with plaster of Paris, in the proportion of four parts of the former to three of the latter, gives a tint very near resembling ivory; precipitated carbonate of barytes gives a tint interme. diate between the two. - The method of making Whity Brown Paper is the following; The constituent material consists in old worn-out sacks, which are first chopped into small pieces by a labourer, who is for that purpose furnished with a sharp chopper and a block; the fragments thus prepared are weli washed by agitating them in a vat of water, changed as often as needful; after this they are cast into the mill, which consists of a longitudinally denticulated cylinder, or roller, not much unlike the crimping roller used by a laundress for crimping frills, &c.; this roller having a motion given it by a water wheei, revolves on its axis with great velo- city, within the fixed concave section of a cylinder, likewise denticulated, and fitted so closely to it, but without contact, as to grind the shreds of sacking, which are now mixed with water to a fine pulp, as they are drawn in between the two surfaces. This part of the apparatus is contained in one side or division of a trough, of an oblong curvated form, with a par- tition in the middle, leaving it open at each end, thus forming a continuous canal in which the fluid moves round, the current which passes through the grinders being occasioned by the répid revolution of the indented roller in the liquid. When the fibres have thus acquired a proper state of separation, the pulp is suffered to run out of the mill trough into a large receptacle, to await the next process. A sufficient portion is now transferred into another vat, where it is further diluted with water to a proper consistence, and moderately warmed by steam, circulated in pipes at the bottom of the vessel, and to prevent the pulp precipitating, the whole is kept in constant motion by an apparatus somewhat like a reel, revolving within at the lower part, and put in action also by a small water wheel. In this state, the colour, the consistency, and the ebullition, cause it to bear a striking resemblance to a huge mass of water gruel, “thick and slab.” At this vessel stands a man furnished with a frame of wirework, very similar to what is used for meat safes, but of a closer texture, and not much unlike a four-sided shallow sieve, and of the size and form of the sheet of paper to be made ; this he dips into the liquid, and on lifting it out the water drains through the wirework, and the frame is covered with a thin layer of the pulp; the frame is then inverted on a piece of flannel, when the pulp quits the frame, and lying on the flannel, resembles, and is in fact become, a sheet of wet paper: another flannel is laid on this for the next sheet, and so alternately, until the pile has accumulated to a certain quantity, when the whole is put into a powerful press, by which the water held in the material is expressed, and the paper thus brought to a state of comparative dryness. Each sheet is now taken from between the flannels, and hung across laths in the drying rooms: when dry, is made up into quires, again pressed, and packed up in reams for the consumer. PAPER Office, an office in which all the public writings, mat- 764 P A R. DICTIONARY OF MECHANICAL SCIENCE. P A R ters of state and council, proclamations, letters, intelligences, negotiations abroad, and generally all despatches that pass through the office of the secretaries of state, are lodged by way of library. - - .. PAPIER MACHE, is a substance made of cuttings of white or brown paper, boiled in water, and beaten in a mortar, till they are reduced into a kind of paste; and then boiled with a solution of gum arabic, or of size, to give tenacity to the paste, which is afterwards formed into different toys, &c. by pressing it into oiled moulds. When dry, it is covered with a mixture of size and lamp black, and afterwards warnished. . PAPISTS, persons professing the popish religion. By Seve- ral statutes, if any English priest of the church of Rome, born in the dominions of the crown of England, come to England from beyond the seas, or tarried in England three days, without . conforming to the church, he was guilty of high treason; and they also incurred the guilt of high treason who were reconciled to the see of Rome, or procured others to be reconciled to it. By these laws also, papists were disabled from giving their children any education in their own religion. If they educated their children at home, for maintaining the schoolmaster, if he did not repair to church, or was not allowed by the bishop of the diocese, they were liable to forfeit 10l. a month, and the school- master was liable to ther forfciture of 40s, a day; if they sent their children for education abroad, they were liable to a for- feiture of 100l. and the children so sent were incapable of inhe- riting, purchasing, or enjoying any lands, profits, goods, debts, legacies, or sums of money : saying mass was punishable by forfeiture of 200 marks; and hearing it, by a forfeiture of 100l. - But during the late reign the Roman Catholics have been in some measure relieved from many of the odious and unjust re- strictions formerly imposed on them. See 18, Geo. III, c. 60; and 31 Geo. III. c. 22. Yet as the statute 1 William and Mary, st. I, c. 18, called the Toleration Act, does not apply to Cath9- lics, nor to persons denying the Trinity, they cannot serve in corporations, and are liable to the test and corporation act. They cannot sit in the house of commons, nor vote at elections, without taking the oath of supremacy, and cannot presert to advowsons, although Jews and Quakers may. But the person is only disabled from presenting, and still continues patron. It seems they may serve on juries; but Catholic ministers are exempted. They also are entitled to attend the British facto- ries and their meetings abroad, and may hold offices to be wholly exercised abroad, and may also serve under the East India Company. They are also enabled to hold any rank in the army, having been excused by a late statute from the oaths formerly required. In Ireland, papists may be justices of the peace, and are qualified to serve in corporations; but party spirit much prevailing, they are seldom elected. PAPYRUS, a famous reed, or species of dog grass, from which was made the celebrated paper of Egypt. PAR, in Commerce, signifies any two things equal in value. PARABOLA, is one of the conic sections formed by the intersection of a plane and a cone, when the plane passes parallel to the side of the cone. This figure, like all other conic sections, may be treated of in three different ways, viz. 1. As being produced by the intersection of a plane and cone. 2. Ac- cording to its description in plano. And, 3. As being gene- rated by the motion of a variable line or ordinate, along another fixed line or directrix; in which case the properties of the curve are deduced from the equation by which it is defined or expressed. The vertex of a para- TE: bola is the point in which the cut- - º - ting plane meets the side of the come. Thus, V is the vertex of the parabola m Wo. The axis is a straight line, V n, drawn from the vertex V, so as to divide the figure into two equal parts; and any line parallel to the axis is called a diameter. If a straight line, ter- . minated by the curve, be bisected by the axis or by a diameter, it is called a double ordinate to the axis, or to that diameter, respec- tively; and its half is called an ordinate to it. The axis cuts its ordinates at right angles, Thus M N O is a double ordinate, and M N an ordinate to the axis V m. The segment of the axis, or of a diameter, between its vertex and ordinate, is called an absciss of the axis, or of that diameter. Thus V N is an absciss of the axis.’ A third proportional to the absciss, and its corresponding ordinate, is called the parameter, or latus rectum. The focus is that point in the axis where the absciss is equal to one-fourth of the parameter to the axis. The double ordinate, drawn through the focus, is called the parameter to the axis, or the principal latus rectum. - PARACENTRIC Motion, is the motion of a planet towards the centre of attraction, or the sun. The orbits of the planets being elliptical, they are sometimes nearer, and sometimes more remote, from the sun; and the difference in this distance is what is called the paracentric motion. . . . PARADE, in War, is a place where the troops meet to go upon guard, or any other service. In a garrison, where there are two, three, or more regiments, each have their parade ap- pointed, where they are to meet upon all occasions, especially upon any alarm. And in a camp, all parties, convoys, and de- tachments, have a parading place appointed them at the head of some regiment. • - - PARADISEA, bird of Paradise; in Natural History, a genus of birds of the order Picae, and they chiefly inhabit North Gui- nea, from which they migrate in the dry season into the neigh- bouring islands. They pass in flights of thirty or forty, headed by one whose flight is higher than that of the rest. They are often distressed by means of their long feathers, in sudden shift- ings of the wind, and unable to proceed in their flight are easily taken by the natives, who also catch them with birdlime, and shoot them with blunted arrows. They are sold at Aroo for an iron nail each, and at Banda for half a rix dollar. Their food is not ascertained, and they cannot be kept alive in confine- ment. The smallest bird of paradise is supposed by Latham to be a mere variety of the above. It is found only in the Papuan islands, where it is caught by the natives often by the hand, and exenterated, and seared with a hot iron in the inside, and then put into the hollow of a bamboo, to secure its plumage from injury. - PARADOX, in Philosophy, a proposition seemingly absurd, as being contrary to some received opinion; but yet true in fact. PARAGRANDINE. A new invention, whose object is to avert hail storms, as the electrical conductors serve to obviate danger from lightning. In this climate, the hail is seldom so violent as to occasion any very scrious losses; but in many parts of the continent, it is dreaded as the most destructive enemy of the husbandman ; and we have known insurance companies established for the sole purpose of guarding against loss by hail-storms. The inventor of the Paragrandine is a Signor Apostolla. One of the latest accounts of its beneficial effects, published by Signior Antonio Perotti of San Giovanni di Cassara, states, that having on a piece of land belonging to himself, containing 16,000 perches in extent, fixed up several of the Paragrandini, he had the satisfaction to find that no injury was done by hail to the corn, and very little to the vines, although no less than fourteen storms had occurred in the cur- rent year, five of which appeared to threaten great mischief to his fields, but passed over them, and fell on the neighbouring lands of Valvasoni, Baguarola, and Savorganno. These instru- ments are composed of metallic points and straw ropes, bound together with hempen or flaxen threads. Dr. Astolfi, in a let- ter to professor Francesco Orioli of Bologna, relates, that a hail storm proceeding in a direction from Bentivoglio to S. Giovanni Triano, came near the lands of Count Chenef, which were protected by Paragrandini; on approaching which i the Paragrandine, much rain fell, and the lightning did con- the clouds were seen at once to disperse. A notice, contained in an official report to the Milan government by the Gonfalo- nieve of San Pietro in Casale, states, that during a stormy day, when there were many claps of thunder and flashes of light- ning, he went out to observe the effects of the Paragrandine, and noticed the electric fluid to be attracted by the points of the straw in the machine, around which the flame played in graceful curves; while in the adjoining fields not protected by siderable mischief. - P A R P A R 765 DICTIONARY OF MECHANICAL scIENCE. *. PARAGUAY TEA. A modern writer, giving a description' o the province of Buenos Ayres, (the population of which he estimates at 1,100,000,) says, the Paraguay tea is an article of the greatest importance all over that part of the continent. It is a plant which rises about 13 feet high, with slènder branches. and leaves, something like those of senna. The herb is, in general and almost universal use. It is infused, and made. nearly the same way as China tea, excepting that the branches are put in along with the leaves, and that it is drunk out of the vessel that it is made in, through a silver and glass pipe, as soon as possible. The smell and colour of this drink is said to be equal to the Chinese teas. None of this tea had, in 1826, reached England, so that its merits must be taken on report. As our commerce, however, increases with the South American countries, some of this herb will naturally find its way into Britain, and if it should prove acceptable to the general taste, and become a rival to the China tea, it would be an important staple in the commerce of the two countries. PARALLATIC ANGLE, is the angle subtended by two lines drawn from the centre of a planet, the one to the centre of the earth, and the other to the same point on its surface. See PARALLAX. - - t f PARALLAX, in Astronomy, an arc of the heavens inter- cepted between the true and apparent place of any of the heavenly bodies; that is, between its place as viewed from the centre of the earth, and from some point on its surface. Thus, let. A B C be the earth, C its centre, v'." t v v'v" three different planets, or three TV , diſferent positions of the same planet; - then its true places in these positions, ** / as seen from the centre C, and as re- + v /, ferred to the heavens, will be V V'V"; º) but their apparent, places will be w, w', w", and the arcs wV, wV', and V" w”, will be the measures of the parallax- es, or of the parallactic angles V v w, v'v' wº, &c. or of D v c, D v' C, &c. to which they are equal. - . . - The Horizontal PARALLAX, or that which has place when the star is in the horizon, is the greatest; the angles-and arcs both diminish from the horizon to the zenith, where it becomes nothing, as is obvious from the above figure. Whence it is obvious, that the parallax diminishes the apparent altitude of a body; but that this diminution is less and less, as the altitude becomes greater and greater; and it has, therefore, a contrary - 40 º . effect to refraction, which always increases the apparent height | of any of the celestial objects. Parallax receives particular denominations, according to the circle upon which it is com- outed. • * - p PARALLAx of Altitude, is the difference between the true and apparent altitude of a planet, as above described. PARALLAX of Right Ascension and Descension, is an arch of the equinoctial, by which the parallax of altitude increases the ascension and diminishes the descension. - PARALLAx of Declination, is an arch of a circle of declination, by which the parallax of the altitude increases or diminishes the declimation of a star. º . . . PARALLAx of Latitude, is an arch of a circle of latitude, by which the parallax of altitude increases or diminishes the latitude. . - - Menstrual PARALLAx of the Sun, is an angle formed by two right lines; one drawn from the earth to the sun, and another drawn from the sun to the moon, at either of their quadratures. PARALLAx of the Annual Orbit of the Earth, is the difference between the heliocentric and geocentric place of a planet, or the angle at any planet subtended by the distance between the earth and sum. - PARALLAx of the Planets. The exact determination of the parallax of the planets is of the greatest importance in astro- nomy, as it is from that, or indeed from the parallax of any one of them, we estimate their several distances. For if the paral- lax; or the angle which is subtended by the terrestrial radius, at any planet be known, its distance from the , earth is also known ; whence its distance from the sun, as also the distances of all the other planets, will be known also, from the third law. of Kepler, viz. that the squares of the periodic times are as the 78. cubes of the distances. To illustrate this it may be observed, that in very small angles, as are those of the parallaxes, and While the side subtending those angles remains constant, the angles will be reciprocally as the distances; that is, if D C be very small with regard to CV, then the angle Div C : angie 12 D M C : : C V : CM nearly. For in this case we may consider DV - C.V and D M = CM, also D C will not differ sensibly from the arc of C - V M the circles which subtends the angles at V and M, and there- º D C - fore putting 3.1416 = p we have 5pxöv for the measure of - - ID C. - - the angles D V C, and 2px CM for the measure of the angle PMC, which are therefore reciprocally as CV and CM. It IS obvious, therefore, that the parallax of any one of the planets being found, that of all the others may be determined, because their proportional distances from the sun are accurately known from Kepler's law, above mentioned. There are Imany differ- ent methods of determining the parallax of the planets; but being an extremely delicate operation, on account of the small- ness, of the angles, we had several different results; till the parallax of Venus was determined by means of her transits over the sun's disc, in 1761 and 1769; and as it is on this, that * great part of our knowledge depends respecting the absolute distances of the planets from the sun, it will be proper to give a sketch of the principles on which it rests, without, however, attempting to enter into the minutiae of the observations and calculations. Let VV" represent the orbit of Venus, and EE that of the earth; V and E being the positions of these two R e - * * * w • w : " " ' " ' --------. . . . . . . . . . . ". .*.*.*.. * T * * * * * * - - - . . . v º:*-* * * T * * * * * * * . . . . *** . . . : - e * * * * * * - - - - - - - * * * * * * * * - #: E ::==<-- * * * * * * * . . . '* * * - - e. . . . . . . . . ; ; ; F * **** S; • = • * * * * : : : * : * * * t tº prº • * * * 2 *-*** : * * * & à ºft -- § Ž. - r * - * * * º ſº - %. º º * º-º ſe i s㺠- l - , a : $3% §: - * . . *, *.. . . . . . Sº tº ..º.º. S; • * * * §§ ! --------- * * * ..iº. * - - - - * * :* • . . . . . ~ * * * • ' ' ... • * * * º * . . . . ~ * * * * * . . ! . . . . . . --- - - " " f, . . . . . . * * * * * 4) , - - - * t te º bodies at the true time of Venus entering upon the disc of the sun, that is, to an observer situated at the earth’s centre, by whom her place in the heavens would be referred to v, which would be also the place of the eastern limb of the sum. But to an observer situated at A, Venus would be referred in the heavens to w, and the eastern limb of the sun to s ; and conse- quently, to such an observer, Venus, instead of appearing on - the sun’s disc, would be distant from him by the arc SW, that is, by an arc equivalent to the difference of the parallax of Venus and of the sun. And in the same manner, supposing the earth, during the transit, to have moved in its orbit from E to E', and Venus from V to V’; it is obvious, from what is said above, that at the time when this planet was just quitting the sun’s western limb, to an observer situated at the centre E, would be referred by an observer at A to v', and the western limb of the sun at s'; so that, in the first case, she would not enter the sun’s disc till after the true time, and in the latter, she will appear to leave the sun's disc before the true time; and as in some parts of the world, in the transit above alluded to, Venus was seen both to enter and emerge from the sun's limb by the same observer, the whole difference between the true and apparent time of the transit became known, and half this difference was the time Venus was in passing over the arc ws; whence the measure of that arc became known, or, which is the same, the difference between the parallax of Venus and that of the sun. But to those observers who could not see both the immersion and emersion, the difference between the true and apparent time of either, when converted into seconds of a degree, was what determined the difference of the paral- lax of the two bodies. Now this difference being known, as 9 I 766 P A R. ..P. A. R. DICTIONARY OF MECHANICAL SCIENCE. also the proportional distances of the Earth, Venus, and the Sun, their absolute parallaxes were determined, this, as we have shewn above, being reciprocally as the distances. Let m : n represent the ratio of the distance E v. to E S, also P and p the parallaxes of Venus and the Sun, which are required, and P–p = q, the difference of their parallaxes as found above; then, n : m :: P : p, whence n – m : m :: P - p = q : m—m T - sequent observations, &c., Laplace has determined the paral- Iax of the sun to be 8"#, whence its distance is found to be about 94 million miles. And hence the parallaxes of the several planets are determined as follows:—Greatest horizontal paral- jax of the Sun, 8".75; Mercury, 14".58; Venus, 29".16; Mars, 17".50; Jupiter, 2.08; Saturn, 1"027; Uranus, 0°415. PARALLAx of the Moon. This is much more considerable than in any other of the heavenly bodies, on account of its proximity to the earth, and is much easier determined than any of the others; one of the most simple and correct methods being as follows:–Observe the moon's meridian altitude with the greatest accuracy, and mark the moment of observation: this time being equated, compute her true longitude and lati- tude, and from these find her declination; and from her decli- nation, and the elevation of the equator, find her true meridian altitude ; if the observed altitude be not meridian, reduce it to the true time for the time of observation; take the refraction from the observed altitude, and subtract the remainder from the true altitude, and the remainder is the moon’s parallax: by this means the parallax of the moon has been found as follows, viz. Greatest parallax, 61' 32". Least parallax, 54' 4". Mean parallax, 57' 48". But Laplace makes her mean parallax 56' 34.2. - - - PARALLAx of the Fixed Stars. As the distances of the heavenly bodies are determined by means of their parallaxes, every possible method has been attempted to ascertain the parallax of some of the fixed stars, but their distance is so immense, that not only have they no parallax, as compared with the terrestrial radius, but even the whole diameter of the earth's orbit, though near 200 million miles, is not sufficient to render any difference in their apparent places at all evident, wnich, if it only amounted to one second, would be discoverable by modern instruments. This distance, therefore, great as it is, is not more than a mere point compared with the distance of the nearest of the fixed stars. - PARALLEL Motion, is a term used among practical me- chanics to denote the rectilinear motion of a piston rod, &c. in the direction of its length ; and contrivances by which such , the sun's parallax. In this manner, aided by sub- alternate rectilinear motions are converted into rotatory ones, and vice versa, in pumps, steam-engines, saw-mills, &c. are usually called contrivances for parallel motions. In motions of this kind it is generally thought a desirable thing to give the piston rod, the saw, or the like, a uniform velocity through the whole of its progress; then to bring it at once to rest, again to. give it instantaneously a finite velocity in the opposite direc- tion, and so on. But this seems impossible in nature; all changes of motion which we observe are gradual, because all impelling bodies have some elasticity or softness by which they yield to compression; and, in the way in which pistons are commonly moved, viz. by cranks, or something analogous to them, the motion is very sensibly gradual. be observed, that most attempts to correct these inequalities in motion are misplaced ; and if they could be accomplished, would greatly injure the pump or other machine. One of the best methods of producing this effect is, to make the piston rod consist of two parallel bars, having teeth in the sides which Let a toothed wheel be placed between front each other. them, having only the half of its circumference furnished with teeth. It is evident, without any further description, that if this wheel be turned uniformly round its axis, the piston rod will be moved uniformly up and down without inter- mission. This has often been put in practice, and the piston rod made to work between grooved rollers; but the machine always went by jolts, and seldom lasted a few days. Unskil- led mechanists attributed this to defect in the execution; but the fault is essential, and lies in the principle, The machine Hence, it may could not perform one stroke if the first mover did not slacken a little, or the different parts of the machine did not yield by bending, or by compression; and no strength of materials could withstand the violence of the strains at every reciprocation of the motion. This is chiefly experienced in great works which are put in motion by a water wheel, or some other equal power exerted on the mass of matter of which the machine consists. The water wheel being of great weight, moves with considerable steadiness or uniformity; and when an additional resistance is opposed to it by the beginning of a new stroke of the piston, its great quantity of motion is but little effected by this addi- 'tion, and it proceeds very little retarded ; and the machine must either yield a little by bending and compression, or go to pieces, which is the common event. Cranks are free from this | inconvenience, because they accelerate the piston gradually, and bring it gradually to rest, while the water wheel moves round with almost perfect uniformity. The only inconvenience (and it may be considerable) attending this slow motion of a piston at the beginning of its stroke is, that the valves do not shut with rapidity, so that some water gets back through them. But when they are properly formed; and loaded, this is but trifling. It would seem, then, that those contrivances in which the piston rod communicates the rotatory motion by means of a crank, or something similar in its effect, are most fit to be adopted in practice; and that the attempts of mechanists in this point of view may, in all probability, be properly restrained to the methods of keeping the piston, rod, &c. from deviating to any side, during its alternate motion. Two or three of the best methods of performing this, with which we are acquainted, are the following:— - - . . . . 1. Let a fixed circular ring, whose diameter is equal to the stroke of the piston, have teeth all round the interior parts of its circumference ; and let a smaller wheel, whose diameter is only half that of the ring, have equal teeth on the exterior part of its rim, to play into the teeth of the ring ; let the axis of the wheel, to which the rotatory motion is to be communicated, pass through the centre of the larger ring ; and let a moveable bar join the centre of this ring to that of the smaller wheel. Then, if the upper extremity of the piston rod be attached to a pin fixed on the rim of the inner wheel, at the place where the two wheels are in contact in their lowest point, and the rod be put into motion, it will cause the small wheel to revolve upon the inner part of the fixed ring, and by this means give the proposed rotatory motion to the axis passing through the centre of the ring. At the same time, the extremity of the piston rod will be confined to move in the vertical diameter of the ring ; because it is made to describe an epicycloid of that kind, which is formed by a circle rolling along the inside of another circle of double diameter; in which case, it is well known, the epicy- cloid becomes a diameter of the larger circle, and the smaller circle makes two complete revolutions, while it is moving from any one point of the larger circle to the same point again. This contrivance was devised, we believe, by Mr. White, an Anglo- American. It is almost unnecessary to observe, that the con- verse is equally applicable in the conversion of a rotatory into a parallel motion. - " . . . . . " , “ . . * . . . ; 2. Another method is represented in fig.2, where the piston rod is kept from deviation. A is the cylinder, B the piston, C the pis- ton rod, D the crank, and E the connecting rod of the crank and piston rod. When the piston is at e, the crank is at a ; when the piston is at B, the crank is either at g or b ; and when the piston is at g, the crank is at f; so that when the motion of the crank is uniform, that of the piston is variable. . The rod H, equal in length to the crank D, moves about the centre F, and is joined to one end of the rod I; to the other end of which is connected the socket L, that receives the top end of the piston rod. A certain point m is taken at pleasure in the rod I, to carry a short axle for the rods K, which are broken in the figure to shew the socket L. To find the centre of motion of the rods K, move the end L of the rod I up and down in the vertical line cfa, and mark three positions R, m, r, of the point m on that rod; describe a circle to pass through those three. points; its radius will be equal to the length of the rods K, and its centre will be the point where those rods must be fixed to a bolt or axle in the framing. This contrivance causes the top of the piston rod to move from P by L to O, and back P. A. R. P A R 767 DICTIONARY OF 'MECHANICAL SCIENCE. ‘again by L. to p; and the . . dotted lines shew the posi- * * ~ * tion of the several rods at . . . ,” # “, the extremities of the mo- - ,” t tion. In fig. 3, we have given a horizontal section, to shew the connexion of H, I, K, &c. pointing out in what way I grasps L, and E r \ ; : both. The inequality of the - V., #: .# piston’s motion will be re- • . duced by making the con- - ; : necting rod E as long as cir- ::: ** cumstances will permit. If \\ }; ; ," the rod I were extended to. .M.9) the left of the point p, the lº. o: same kind of apparatus ...?” ..., \\-3 would become a lever with a moveable fulcrum, by means of which a weight might be ‘..…."; "| raised in a vertical line from g\\}; *::::: 2:..:#" P to O ; or a pump piston TV; º, rod worked without devia- ? ‘. . . . . ...; tion. IF - . . This construction is de- scribed in a prismatic form, * * * * * * * * by Professor Playfair, in his - - Outlines of Nat. Philosophy, || C. vol. i.i.art. 355. - 3. A third method is ex- * - - hibited in fig. 1, where are - three rods A, B, and C, be- sides the connecting rod D. The rods A and C are of: equal lengths, and the con- necting rod is attached to the middle point of the rod B. The guides A, , and C, are fixed at their ends E and FI • R. F, by bolts to the framing. º Q # the point B, to which i. l, # is fixed the top of the piston . I m. IEA rod, is made to move in the Iº. Tºy |K. right line b Bb'; and the - * , , dotted lines shew the positions of the Fig. 1 rods at the extremities of the stroke. --ſºº... This method, and the preceding, were ...“ (: “... devised by Mr. William Dryden, a * # *... " mechanic whose ingenuity needs not our encomium. º 4. Another method is shewn in fig. 4. A and B are two bolts in the framing at equal distances on opposite sides of the vertical line in which the pis- ...ton is to move. A C, B D, two bars of equal length, each equal to about Fig. 4. half the dis- tance A. B. CL, DL, two other equal bars, rather more than double the length of the former, mov- ing freely on joints at C and D. At L. is a socket, as in figure. 2, to receive the top of the --|- piston rod, and to which the bars C L, DL, and the connecting rod E, are attached. By this contrivance it is obvious, that as the rods B C, BD, turn upon the centres A, B, in contrary directions, the piston rod will be made to move in the right £ ..] a line that differs insensibly from a straight line. | use of this instrument is obvious; for applied to a given line, another drawn along the extreme edge | line PM without deviation; NM being the length of the stroke. The relative lengths of the bars A C, CL, may be | varied at pleasure; but those we have mentioned will be found as well as any in practice. - - - Af - ... 5. A piston rod may also be kept from deviating to either side, while it gives motion to a crank, and vice versa, thus: place a cross bar at a distance from the end of the cylinder, rather greater than the stroke of the piston, and make the pis- ton rod play in a hole made in the cross bar; let an axle be fixed to a proper point of the piston rod between the end of the cylinder and the cross bar, and from this axle let two equal connecting rods pass to the crank, one on each side the cross | bar: by this simple contrivance, the alternating and circular | motions may be communicated to the different parts of the machine with great facility. - 6. A rectilinear vertical motion may, again, be produced thus:–Two of the adjacent angles of a parallelogram are made to describe concentric circles, so that the side between them passes through their centre, and one of the remaining angles another circle having its convexity opposed to that of the two former, then the fourth angle of the parallelogram will describe This con- struction is the invention of Watt, and now very common.— Gregory's Mechanics. - PARALLEL, in Geometry, is applied to lines, figures, and bodies, which are every where equidistant from each other, or which, if ever so far produced, would never meet. PARALLEL Right Lines, are C P —” those which, though infinitely \ produced, would never meet; - - which is Euclid's definition. To draw a line C D parallel to a 3– à is given line A, B through a given - point P. From P draw any line meeting A B in some point. Q; then make the angle Q P D = the angle A QP, so shall D PC be the parallel line | required. This in practice is better done by a parallel ruler. PARALLEL Ruler, an instrument consisting of two wooden, | brass or steel rulers, A B and CD, equally broad throughout, and so joined together P. Tº . H. –$ by the cross blades - —9 E F and G H, as to | \ open to different inter- - - vals, and accede and R- E. *— He recede, yet still retain their parallelism. The one of the rulers being of the other, will be parallel to it; and thus, having given only one line, and erected a perpendicular upon it, we may draw any number of parallel lines or perpendiculars to them, by only observing to set off the exact distance of every line with the point of the compasses. But the best parallel rulers are those whose bars cross each other, and turn on a joint at their intersection; one of each bar moving on a centre, and the other ends sliding in grooves as the rulers recede. PARAllels of Latitude, in Astronomy, are lesser circles of the sphere parallel to the ecliptic, imagined to pass through | every degree and minute of the colures. PARALLels of Altitude. Almucahters, are circles parallel to the horizon, imagined to pass through every degree and minute of the meridian between the horizon and zenith, having their poles in the zenith. They are represented on the globe by the division on the quadrant of altitude, in its motion about the body of the globe, when screwed to the zenith. - PARALLELs of Declination, in Astronomy, are the same with parallels of latitude in Geography. - a " PARALLEL Sphere, that situation of the sphere wherein the equator coincides with the horizon, and the poles with the zen- ith and nadir. In this sphere all the parallels of the equator become parallels of the horizon, consequently no stars ever rise or set, but all turn round in circles parallel to the horizon ; and the sun, when in the equinoetial, wheels round the horizon the whole day. After his rising at the elevated pole, he never sets for six months; and after his entering again on the other sidé of the line, never rises for six months longer. 768 P A R. Tº A. R. DIGITIONARY OF MECHANICAL | SCIENCE. PARALLEL Sailing, in Navigation, is the sailing' under a parallel of latitude. See NAVIGATION. * PARALLELISM of the Earth’s Aaris, is used to denote that invariable position of the terrestrial axis, by, which it always points to the same point in the heavens, abstracting from the * * * - . . . . . . . stays, &c. and is firmly fastened by marline from one end to the PARALLELOGRAM, in Geometry, is a quadilateral right- - * - trifling effect of mutation, &c. : See NUTATION. : lined figure, whose opposite sides are parallel. , º PARALLELog RAM receives particular denominations, accord- ing to the equality or inequality of its sides and angles. Thus, a rectangle, rhombus, rhomboid, and square, are each a particular species of parallelograms, for the properties of which see the several articles. Other properties, common to every parallelo- gram, may be enumerated as follows:–1. A parallelogram has its opposite sides and angles equal to each other, and the 2. The two diagonal divides it into two equal triangles. adjacent angles of any parallelogram are, together, equal to two right angles. 3. Parallelograms having equal bases and altitudes, are equal ; on equal bases they are to each other as their altitudes; and with equal altitudes they are to each other as their bases; and generally parallelograms are to each other in the compound ratio of their bases and altitudes. 4. The sum of the squares of the diagonals of any parallelogram, is equal to the sum of the squares of the four sides. 5. The complements about the diagofials of any parallelogram are equal to each other. PARALLELoGRAM of Forces, is a term used to denote the com- position of forces, or the finding a single force that shall be equivalent to two or more given forces when acting in given directions. . . ... PARALLELOPIPED, in Geometry, a regular solid, com- prehended under six sides, or parallelograms, the opposite ones of which are similar, parallel, and equal to each other. D C Aſ PARALLOGISM, in Logic, a false reasoning, or a fault com- mitted, in demonstration, when a consequence is drawn from principles that are false; or, though true, are not proved; or when a proposition is passed over that should have been prov- ed by the way, " * -- " PARAMETER, a certain and constant right line in each of the three conic sections, and otherwise called the Latus Rectum. PARAMOUNT, the supreme or highest lord of the fee. ... PARAPET, in Fortification, an elevation of earth designed for covering the soldiers from the enemy’s eannen: or small shot. PARAPHERNALIA, are the women's apparel, jewels, and other things, which in the life-time of her husband she wore as the ornaments of her person, to be allowed by the discretion of the court, according to the quality of her and her husband. The husband cannot devise such ornaments and jewels of his wife, though during his life he has power to dispose of them. But if she continues, in the use of them till his death, she shall after- wards retain them against his executors and administrators, legatees, and all other persons, except creditors where there is a deficiency of assets, 2 Black, 436. * - PARAPHRASE, an explanation of some text, in clearer and more ample terms; whereby is supplied what the author might have said, or, thought on the subject; such are esteemed Erasmus's Paraphrase on the New Testament, the Chaldee Paraphrase on the Pentateuch, &c. . -- - PARASANG, an ancient Persian measure, different at dif- ferent times, and in different places; being sometimes 30, some- times 40, and sometimes 50 stadia or furlongs. - - PARASELINE, a mock moon, seen usually in a ring sur- rounding the moon. ; - PARASITEs, or Parasitical Plants, in Botany, such plants as are produced out of the trunk, or branches of other. plants, from whence they receive their nourishment, and will not grow upon the ground; as the mistletoe, &c. p PARBUCKLE, is a contrivance to haul up or lower down a cask, &c. where there is no crane, or tackie; it is formed by: passing the middle of a rope round, a post or ring, or under a boat's thwart; the two parts of the rope are then passed under. the two quarters of the cask, bringing the two ends back again. over it, which being both hauled, or slackened together, either - ... .] but they must be pleaded. 3 Inst. 283. ; raise or lower the barrel, &c. as may be required. J PARCELLING, long narrow slips of canvass, and fréquéntly bound about a rope in the manner of bandages, previous to its being served. It is laid in spiral twines as smoothly upon the surface as possible, that the rope may not become uneven and full of ridges. Parcelling is also used to raise a mouse on the other. Parcelling a Seam, is the laying a slip of canvass upon it, and daubing it over with melted pitch. . . . . . PARCEL MAKERS, two officers in the exchequer, who make parcels of the escheators’ accounts, in which they charge them with every thing they have levied for the king’s use, within the time of their office, and deliver the same to one of the auditors of the court to make their accounts therewith. PARCHMENT, is the skin of sheep or goats, prepared for writing, and covering books. The skin is stripped of its wool, and passed through the lime pit. The skinner then stretches it on a frame, perforated longitudinally with holes furnished with wooden pins that may be turned at pleasure, like those of a violin, to stretch the skin like a drum head. The skin being thus 'sufficiently stretched on the frame, the flesh is pared off with a sharp instrument; it is then moistened with a rag, and white chalk reduced to a fine dust, strewed over it; then with a large pumice stone, the workman, rubs over the skin, and thus scours off the remains of the flesh. They then go over it again with an iron instrument; moisten it as before, and rub underneath with pumice stone without any chalk; this smooths and softens the flesh side very considerably. . They drain it again, by passing over it the iron, instrument as before... The flesh side thus drained, they pass the iron on the hair side; then stretch it tight on the frame by means of the pins, and go over the flesh side again with the iron; this finishes its drain- ing : the more the skin is drained, the whiter it becomes. They now throw on more chalk, sweeping it over with a piece of Iamb skin that has the wool on ; this smooths it further, and gives it a white knap. When dried, it is taken off the frame, by cutting all round. The skin, thus far prepared by the skin- ner, is taken by the parchment-maker; who first scrapes- or pares it dry on the summer, which is a calfskin stretched in a frame, with an iron instrument like that above named, only finer and sharper; with this, worked with the arm from the top to the bottom of the skin, he takes away one-half of its thick- ness, and the skin thus equally pared on both sides, is rubbed with the pumice stone to smooth it. This last preparation is performed on a bench covered with a sack stuffed with flocks, and it leaves the parchment fit for writing upon. - - WELLUM, made from the skins of sucking calves, possesses a finer grain than parchment, but it is prepared in the same manner, without however being passed through alum water. PARDIES, IGNATIUS GAston, an ingenious French mathe- matician, was born in the province of Gascony, in 1636, and died in 1673, when only 37 years of age. - PARDON, in a religious sense, is an exercise of the divine placability towards repentant offenders. It is nearly the same as grace and favour, and is conferred on those who comply with the terms or conditions of the gospel, which are faith, re- pentance, and future obedience. . It is a result of the sove- reignty of Almighty God; and is therefore given without any consideration of reward, satisfaction, or advantage to the offended. | - . . . . " PARDON, in a legal sense, is the remitting or forgiving a felony, or other offence committed against the king. Black- stone mentions the power of pardoning offences to be one of the greatest advantages of monarchy in general, above every other form of government; and which cannot subsist in demo- cracies. Its utility, and necessity are defended by him on all those principles which do honour to him and human nature. See 4 Black. 496. Pardons' are either general or special : ge. neral, as by act of parliament, of which, if they are without ex- ceptions, the court must take notice ea officio ; but if there are exceptions therein, the party must aver that he is none of the persons excepted. 3 Inst. 233, Special pardons, are either of course, as to persons convicted of manslaughter, or se defen- dendo, and by several statutes to those who shall disèover their accompliees in several felonies; or of grace, which are by the king’s charter, of which the court cannot take notice ea efficio, . P A R. E. A. R. 763 DICTIONARY OF MECHANICAL SCIENCE, A pardon may be conditional, that is, the king may extend his mercy upon what terms he pleases; and may annex to his bounty a condition either precedent or subsequent, on the per- formance whereof the validity of the pardon will depend, and this by the compaon law. 2 Hawk. 37. - - PARENT, ANTHONY, a reputable French maathematician, was born in Paris in 1666, and died in 1716, having at his death numerous manuscripts on various mathematical and philosophi- cal subjects, , , - * PARENTS AND CHILDREN. If parents run away and leave their children at the charge of the parish, the church- wardens and, overseers by order of the justices may seize the rents, goods, and chattels, of such parents, and dispose thereof towards their children's maintenance. A parent may lawfully correct his child, being under age, is a reasonable manner; but the legal power of the father over the persons of his chil- dren ceases at the age of 21. 1 Black. 452. See INFANT. PARENTHESIS, in Grammar, certain intercalary words inserted in a discourse, which interrupt the sense or thread, but seem necessary for the better understanding, of the subject. PARHELION, a mock sun, or meteor of a bright colour, appearing on one side of the sun. Parhelia are more rarely seen than halos, but their appearance is singularly curious. Their apparent size is generally the same as the true Sun ; but they are not always round, nor always so bright as the sun; and when several appear, some are brighter than others. They are tinged externally with colours like the rainbow ; and many of them have a long fiery tail, opposite to the sun, becoming paler towards the extremity. These tails mostly appear in a white horizontal circle, commonly passing through all the par- helia, and would go through the centre of the sun if it were entire. We have on record an account of parhelia seen at Rome, in March, 1629: at this time four were observed, one of which was very much tinged with various colours like the rain- bow; and the others were faintly so. Some were also observed by Cassini, in 1683. In England and Scotland two have fre- quently been seen at a time. In North America they are often seen, and continue four hours, nay, sometimes for several days, being visible from sun-rise, to sun-set; when these disappear, rain or snow is there generally expected. Mr. Huygens, on applying his attention to these appearances, was soon sensible that they could not arise from such globules as formed the halos; yet since parhelia are always attended with halos, he was satisfied that their causes must be much alike. Considering, then, what other figures hail-stones might possibly have, besides a spherical one, he could find no other so simple as that of a cylinder; and, indeed, he had often observed. that snow con- sisted of several slender oblong particles, mixed with those of other shapes; and seeing that small globules were sufficient, for the production of halos, he imagined that a great number of small cylinders, floating in the air, might produce similar ap- pearances. He also remembered that Descartes had taken notice of several small columns, which he had seen lying on the ground, the extremities of which were bounded with flat star- iike figures, consisting of six rays. The large white horizontal circle, observed in some of these phenomena, M. Huygens sup- posed to be produced by the reſlection of the sun’s rays from the outsides of the upright cylinders; since, when the sun shines upon a number of such cylinders suspended in the air, a white circle must necessarily appear to pass through the sun parallel to the horizon. This he shews very distinctly by a large figure of a cylinder, and by pointing out the progress of the sun's rays reflected from it. : For every point of the sun’s ver- tical diameter, as well as his centre, will illuminate a circle of cylinders, of the same apparent height as the illuminating point:—It is observable that no thick clouds are seen in the air when these circles appear; but only such as are very thin, and scarcely visible. For in most of these observations the sky is said to have been very clear and serene ; which agrees quite well with this hypothesis; since these minute cylinders must constitute a very thin cloud uniformly extended, through i. the sun, and even the colour of the sky, may be seen. See ALOS. - . . : PARIS, Herb Paris, or Truelove, a genus of plants belonging to the octandria class, and in the natural method ranking under the eleventh order sarmentaae. - • . . . . 79, - PARIs, Plaster of, is būrnt alabaster, which absorbs waterso: rapidly that in a few minutes it dries. and becomes hard, so that it is greatly employed in making casts for figures; and in ornas mental work among plasterers. . . . . . . . . . . . . . . PARISH. In England there are 9913, parishes, of which 3845 are churches impropriate, and the rest are annexed to colleges or ehurch dignities, In many of these parishes, on account of their large extent, and the number of parishioners, there are several chapels of ease. Parish signifies the precinct of a parish church, and the particular charge of a secular priest. Formerly a parish was synonymous with diocese, and the tithes were paid to any priest whom the party chose ; but it was found convenient to allot a certain district for each priest, that he alone might receive the tithe. It is very doubtful when they originated. Some place the division of parishes in A.D. 650, others in 1179. A parish may contain one or, more vills, but it is presumed to contain only one, and anciently was co-extensive with the manor. Money given by will to a parish is given to the poor. Sometimes by act of parliament a large, parish is subdivided into two or more. + - The extent of parishes is very different in different parts of England. In the northern counties some, parishes contain from twelve to twenty cures of souls, each of the extent of a parish in the southern counties. This is supposed to have arisen from the scanty population at the time of the first division. PARISH CLERK. In every parish, the parson, vicar, &c. has a parish-clerk under him, who is the lowest officer of the church. These were formerly clerks in orders, and their busi- ness at first was to officiate at the altar, for which they had a competent maintenance by offerings, but now they are almost always laymen, and have eertain fees with the parson on chris- tenings, marriages, burials, &c. besides wages for their main- tenance. He must be twenty years of age, and of honest.com- versation, and is generally appointed by the minister, unless there is a custom for the churchwardens and parishioners to elect. It is an office for life, and a freehold. He may make a deputy without license of the bishop. - PARISHIONER, an inhabitant of or belonging to any parish, lawfully settled there. Parishioners are a body politic to many. purposes: as, to vote at a vestry if they pay scot and lot, and they have a sole right to raise taxes for their own relief, with- out the interposition of any superior court; may make by- laws to mend the highways, and to make banks to keep out the sea, and for repairing the church, and making a bridge; and for making and maintaining fire engines. They may also pur- chase workhouses for the poor, or any such thing for the pub- lic good. PARISH-OFFICERS, officers chosen annually to regulate and manage the concerns of the parish. - PARK, a piece of ground enclosed and stored with wild. beasts of chase, which a man may have by prescription or the king's grant. By 16 Geo. III. c 30, if any person shall pull down or destroy the pale or wall of a park, he shall forfeit 30l. PARLIAMENTS, or Gener AL Counc[Ls, in some shape, are of as high antiquity as the Saxon government in this island, and coeval with the kingdom itself. Blackstone, in his valu- able Commentaries, says, “It is generally agreed, that in the main, the constitution of parliament, as it now stands, was marked out so long ago as the 17th of king John, A. D. 1215, in the Great Charter granted by that prince ; wherein he promises to summon all archbishops, bishops, abbots, lords, and greater barons, personally, and all other tenants in chief, under the crown, by the sheriff and bailiffs, to meet at a certain place, within 40 days' notice, to assess aids and scutages when neces- sary. And this constitution hath subsisted, in fact, at least from the year 1266, 49 Henry III. there being still extant writs of that date to summon knights, citizens, and burgesses, to parliament.” The parliament is assembled by the king's writs, and its sitting must not be intermitted above three years, Its constituent parts are, the king sitting there in his royal poli- tical capacity, and the three estates of the realm; the lords spirituai, the lords temporal (who sit together with the king in one house,) and the commons, who sit by themselves in another. The king and these three estates, together, form the great cor- poration or body politic of the kingdom, of which the king is . said to be caput principium et finis. For upon their coming 9 K . - 770 P A R P A R. DICTIONARY OF MECHANICAL SCIENCE. together, the king meets them, either in person, or by represen- tation; without which there can be no beginnings of a parlia-’ ment; and he also has alone the power of dissolving them... It is highly necessary for preserving the balance of the constitu- tion, that the executive power should be a branch, though not the whole, of the legislature. The crown cannot begin of itself any, alterations in the present established law; but it may approve or disapprove of the alterations suggested and con- sented to by the two houses. The legislative therefore cannot abridge the executive power of any rights which it now has by law, without its own consent: since the law must perpetually stand as it; now does, unless all the powers will agree to alter - it. And herein indeed consists the true excellence of the Eng- lish government, that all the parts of it form a mutual check upon each other. In the legislature, the people are a check upon the mobility, and the nobility a check upon the people; by the mutual privilege of rejecting what the other has resolved: while, the king is a check upon both, which preserves the exe- cutive-power from encroachments. . . * The lords spiritual consist of two archbishops and twenty- four bishops. The lords temporal consist of all the peers of the realm, the bishops not being in strictness held to be such, but merely lords of parliament. Some of the peers sit by descent; some by creation: others, since the union with Scot- land, by election, which is the case of the sixteen peers, who represent the body of the Scots nobility. The peers for Ire- land, at present, are 28, but the number is indefinite, and may be increased at will by the power of the crown. - - - - A body of mobility is more peculiarly necessary in our mixed and compounded constitution, in order to support the rights of both the crown and the people; by forming a barrier to with- stand the encroachments of both. It creates and preserves that gradual scale of dignity, which proceeds from the peasant to the prince; rising like a pyramid from a broad foundation, and diminishing to a point as it rises. The nobility therefore are the pillars, which are reared from among the people, more im- mediately to support the throne; and if that falls, they must also be buried under its ruins. Accordingly, when in the 17th century the commons had determined to extirpate monarchy, they also voted the house of lords to be useless and dangerous. The commons consist of all such men of any property in the kingdom, as have not seats in the house of lords; every one of which has a voice in parliament, either personally, or by his representatives. This, however, must be understood with some limitation. Those who are possessed of land estates, though to the value of only 40s. per annum, have a right to vote for mem- bers of parliament; as have most of the members of corpora- tions, boroughs, &c. But there are very large trading towns, and populous places, which send no members to parliament; and of those towns which do send members, great numbers of the inhabitants have no votes. Many thousand persons, of great personal property, have, therefore, no representatives. Indeed, the inequality and defectiveness of the representation has been justly considered as one of the greatest imperfections . in the English constitution. The extension of parliaments to seven years, has also been viewed in the same light. The house of commons, in the reign of Henry VI. consisted of 300 members. In Sir E. Coke's time they amounted to 493. In 1707, they were augmented to 513, for England and Wales; but the union with Scotland taking place in the above year, forty-five representatives were added for that country. In 1801, when the union with Ireland was effected, an additional 100 was introduced, so that the whole house of commons now consists of 658 members; viz. 80 knights for 40 counties in England; 50 citizens for 25 cities, (Ely sending none, and London four,); 334 burgesses for 167 boroughs, and five burgesses for five boroughs, viz, Abingdon, Banbury, Bewdley, Higham Ferrers, and Mon- mouth : four burgesses for the two universities of Oxford and Cambridge; 16 barons for the eight cinque ports, viz. Hastings, Dover, Sandwich, Romney, Hythe, and their three branches, Rye, Winchelsea, and Seaford; 12 knights for 12 counties in Wales; 12 burgesses for 12 boroughs in that country; 30 knights for the shires of Scotland, and 15 burgesses for its boroughs; 64 knights and 36 burgesses for Ireland. Every member, though chosen by one particular district, when elected and returned, serves for the whole realm. For the end of his coming thither is not particular, but general; not merely to serve his constituents, but also the commonwealth, and to advise his majesty, as appears from the writ of summons.--To prevent bribery, the following oath is provided to be administered to every voter prior to his being polled:—“I, — — —, do swear (or being one of the people called Quakers, do solemnly affirm,) I have not received or had, by myself, or any person whatsoever in trust for me, or for my use and benefit, directly or indirectly, any sum or sums of money, office, place or employment, gift or reward, or any promise or security for any money, office, or employment, or gift, in order to give my vote at this election: and that I have not before been polled at this election. So help me God.” * - - - * * These are the constituent parts of a parliament; the king, the lords spiritual and temporal, and the commons. Parts, of which each is so necessary, that the consent of all three is required to make any new law that should bind the subject. Whatever is enacted for law for one, or by two only, of the three, is no statute; and to it no regard is due, unless in mat- ters relating to their own privileges. The power and jurisdic- tion of parliament, says Edward Coke, is so transcendent and absolute, that it cannot be confined, either for causes or per- sons, within any bounds. It hath sovereign and uncontrollable authority in making, confirming, enlarging, restraining, abro- gating; repealing, reviving, and expounding of laws, concern- ing matters of all possible denominations, ecclesiastical, or temporal, civil, military, maritime, or criminal: this being the place where that absolute despotic power, which must in all governments reside somewhere, is entrusted by the constitution of these kingdoms. All mischiefs and grievances, operations and remedies, that transcend the ordinary course of the laws, are within the reach of this extraordinary tribunal. It can regulate or new model the succession to the crown; as was done in the reign of Henry VIII. and William III. . It can alter the established religion of the land; as was done in a variety of instances, in the reign of king Henry VIII. and his three children, Edward VI., Mary, and Elizabeth. It can change and create afresh even the constitution of the kingdom, and of parliaments themselves; as was done by the act of union, and the several statutes for triennial and septennial elections. It can, in short, do every thing that is not naturally impossible; and therefore some have not scrupled to call its power by a figure rather too bold, the omnipotence of parliament. But then their power, however great, was given them in trust, and therefore ought to be employed according to the rules of justice, and for the promotion of the general welfare of the people. And it is a matter most essential to the liberties of the kingdom, that such members be delegated to this im- portant trust, as are most eminent for their probity, their forti- tude, and their knowledge; for it was a known apophthegm of the great lord treasurer Burleigh, “that England could never be ruined but by a parliament:” and, as Sir Mathew Hale ob- serves, this being the highest and greatest court, over which none other can have jurisdiction in the kingdom, if by any means a misgovernment should any way fall upon it, the sub- jects of this kingdom are left without all manner of legal remedy. In order to prevent the mischiefs that might arise, by placing this extensive authority in hands that are either in- capable, or else improper, to manage it, it is provided, that no one shall sit or vote in either.house of parliament, unless he be twenty-one years of age. To prevent innovations in religion and government, it is enacted, that no member shall vote or sit in either house, till he hath, in the presence of the house, taken the oaths of allegiance, supremacy, and abjuration; and subscribed and repeated the declaration against transubstan- tiation, the invocation of saints, and the sacrifice of the mass. It is also enacted, that no alien, born out of the dominions of the crown of Great Britain, even though he be naturalized, shall be capable of being a member of either house of parliament. Some of the most important privileges of the members of either house are, privilege of speech, of person, of their domes- tics, and of their lands and goods. As to the first, privilege of speech, it is declared by the statute of 1 William and Mary, st. 2. c. 2. as one of the liberties of the people, “that the free- dom of speech, and debates, and proceedings in parliament, ought not to be impeached or questioned in any court or place f P A R P A R DICTIONARY OF MECHANICAL SCIENCE. , 771. out of parliament.” And this freedom of speech is particularly demanded of the king in person, by the speaker of the house | of commons, at the opening of every new parliament. So are This includes not only privilege from illegal violence, but also from legal arrests, and seizures by process from the courts of law. To assault by violence a member of either house, or his menial servants, is a high contempt of parliament, and there punished with the utmost severity. Neither can any member of either house be arrested and taken into custody, nor served with any process of the courts of law; nor can his menial ser- vants be arrested; nor can any entry be made on his lands; nor can his goods be distrained or seized, without a breach of the privilege of parliament. This exemption, however, from arrests for lawful debts, was always, considered by the public as a grievance. The lords and commons therefore generously relinquished their privilege by act of parliament in 1770; and The house of lords have a right to be attended, and conse- quently are, by the judges of the courts of king's bench and common pleas, and such of the barons of the exchequer as are of the degree of the coif, or have been made sergeants at law ; as likewise by the masters of the court of chancery ; for their advice in point of law, and for the greater dignity of their pro- ceedings. The speaker of the house of lords is generally the lord chancellor, or lord keeper of the great seal, which digni- ties are commonly vested in the same person. Each peer has a right, by leave of the house as being his own representative, when a vote passes contrary to his sentiments, to enter his dissent on the journals of the house, with the reasons for such dissent; which is usually styled his protest. Upon particular occasions, however, these protests have been so bold as to give offence to the majority of the house, and have therefore been expunged from their journals: but this has always been thought a violent measure, and not very consistent with the general right of protesting. . . . . . - - The house of commons may be properly styled the grand inquest of Great Britain, impowered to inquire into all national grievances, in order to see them redressed. The peculiar laws and customs of the house of commons relate principally to the raising of taxes, and the elections of its members. . With regard to taxes: it is the ancient indisputable privi- lege and right of the house of commons, that all grants of sub- sidies, or parliamentary aids, do begin in their house, and are first bestowed by them : although their grants are not effectual to all intents and purposes, until they have the assent of the other two branches of the legislature. The general reason given for this exclusive privilege of the house of commons is, that the supplies are raised upon the body of the people, and therefore it is proper that they alone should have the right of taxing themselves. And so reasonably jealous are the com- mons of this privilege, that herein they will not suffer the other house to exert any power but that of rejecting; they will not permit the least alteration or amendment to be made by the lords to the mode of taxing the people by a money bill. Under this appellation are included all bills by which money is directed to be raised upon the subject, for any purpose, or in any shape whatsoever; either for the exigencies of government, and col- lected from the kingdom in general, as the land-tax; or for private benefit, and collected in any particular district, as by turnpikes, parish-rates, and the like. wº The method of making laws is much the same in both houses. In each house the act of the majority binds the whole : and this majority is declared by votes openly and publicly given; not as at Venice, and many other senatorial assemblies, pri. vately or by ballot. This latter method may be serviceable, to prevent intrigues and unconstitutional combinations, but is impracticable where a member's conduct must be open to the inspection of his constituents. . . . . . To bring a bill into the house of commons, if the relief sought by it is of a private nature, it is first necessary to prefer a peti- tion; which must be presented by a member, and usually sets forth the grievance desired to be remedied. This petition (when founded on facts that may be in their nature disputed) is referred to a committee of members, who examine the mat: ter alleged, and accordingly report it to the house; and then (or, otherwise, upon the mere petition), leave is given to bring in the bill. In public matters, the bill is brought in-upon mo... - tion made to the house, without any petition. (In the house of the other privileges, of person, servants, lands, and goods. | lords, if the bill begins there, it is, when of a private nature, referred to two of the judges, to examine and report the state. of the facts alleged, to see that all necessary parties consent, and to settle all points of technical propriety.) This is read a first time, and, at a convenient distance, a second time; and after each reading, the speaker opens to the house the sub- stance of the bill, and puts the question, whether it shall pro- ceed any farther. The introduction of the bill may be originally. opposed, as the bill itself may at either of the readings; and if the opposition succoeds, the bill must be dropt for that ses- sion; as it must also, if opposed with success in any of the subsequent stages. After the second reading, it is committed, that is, referred to a committee; which is either selected by the house in matters of small importance, or else, if the bill is members of both houses may now be sued like other debtors. a matter of great or national consequence, the house resolves itself into a committee of the whole house. A committee of the whole house is composed of every member; and, to form it, the speaker quits the chair (another member being appointed chairman), and may sit and debate as a private member. In these committees, the bill is debated clause by clause, amend- ments made, the blanks filled up, and sometimes the bill entirely new-modelled. After it has gone through the committee, the chairman reports it to the house, with such amendments as the committee have made ; and then the house re-consider the whole bill again, and the question is repeatedly put upon every clause and amendment. When the house have agreed or dis- agreed to the amendments of the committee, and sometimes added new amendments of their own, the bill is then ordered to be engrossed, or written in a strong gross hand, on one or more long rolls of parchment sewed together. When this is finished, it is read a third time, and amendments are some- times then made to it; and, if a new clause be added, it is done by tacking a separate piece of parchment on the bill, which is called a rider. The speaker then again opens the contents; and, holding it up in his hands, puts the question whether the bill shall pass. If this be agreed to, the title to it is then settled. After this, one of the members is directed to carry it to the lords, and desire their concurrence; who, attended by several more, carries it to the bar of the house of peers, and there delivers it to their speaker, who comes down from his woolsack to receive it. It there passes through the forms, as in the other house, (except engrossing, which is already dome), and if rejected, no more notice is taken, but it passes sub silentio, to prevent unbecoming altercations. But if it be agreed to, the lords send a message by two masters in chancery (or, sometimes, in matters of high importance, by two of the judges) that they have agreed to the same ; and the bill remains with the lords, if they have made no amendment to it. But if any amendments are made, such amendments are sent down with the bill to receive the concurrence of the commons. If the commons disagree to the amendments, a conference usually follows between members deputed from each house ; who, for the most part, settle and adjust the difference; but if both houses remain inflexible, the bill is dropped. If the com- mons agree to the amendments, the bill is sent back to the lords by one of the members, with a message to acquaint them there with. The same forms are observed mutatis mutandis, when the bill begins in the house of lords. But when an act of grace or pardon is passed, it is first signed by his majesty, and then read once only in each of the houses, without any new engrossing or amendment. And when both houses have done with any bill, it always is deposited in the house of peers, to wait the royal assent; except in the case of a money-bill, which after receiving the concurrence of the lords, is sent back to the house of commons. ... It may be necessary here to acquaint the reader, that both in the houses, and in their committees, the slightest expression, or most minute alteration, does not pass till the speaker, or the chairman, puts the question; which, in the house of commons, is answered by aye or no ; and, in the house of peers, by content, or not content. . . The giving the royal assent to bills is a matter of great form. When the king is to pass bills in person, he appears on his throne in the house of peers, in his royal robes, with the crown P A R. P A R DICTIONARY OF MECHANICAL SCIENCE. on his head, and, attended by his great officers of state and, heralds. A seat on, the right hand of the throne, where the prinees of Sootland, when W. of England, formerly sat, is reserved for the prince of Wales. The other princes of the blood sit on the left hand of the king; and the chancellor on a | close bench removed a little backwards. The viscounts and | - or in turning a serious work into a burlesque, by affecting to temporal barons, or lords, face the throne, on benches, or wool- packs, covered with red cloth or baize. The bench of bishops runs along the house to the bar on the right hand of the throne; as the dukes and earls do on the left. The chancellor and judges, on ordinary days, sit upon wool-packs, between the 3. and the throne. The common opinion is, that the house sitting on wool, is, symbolical of wool being formerly the staple commodity of the kingdom, Many of the peers, on Solemn occasions, appear in their parliamentary robes. None of the commons have any robes, excepting the speaker, who wears a long black silk gown; and when he appears before the king it is trimmed with gold. The royal assent may be given two ways; 1. In person. When the king sends for the house of commons to the house of peers, the speaker carries up the money bill or bills in his hand; and, in delivering them, he addresses his majesty in a solemn speech, in which he seldom fails to extol the generosity and loyalty of the commons, and to tell his majesty how necessary it is to be frugal of the public money. It is upon this occasion, that the commons of Great Britain appear in their highest lustre. The titles of all bills that have passed both houses are read; and the king's answer is declared by the clerk of the parliament in Norman-French. If the king consents to a public bill, the clerk usually declares, le roy le weut, “the king wills it so to be ;” if to a private bill, soit fait eomme il est desiré, “be it as it is desired.” If the king refuses his assent, it is in the gentle language of le roy s'avisera, “the king will advise upon it.” When a money-bill is passed, it is carried up and presented to the king by the speaker of the house of commons, and the royal assent is thus expressed, le roy remercie ses loyal subjects, accepte, leur benevolence, et auff, le veut, “the king thanks his loyal subjects, accepts their bene- yolence, and wills it so to be.” In case of an act of grace, which originally proceeds from the crown, and has the royal assent in the first stage of it, the clerk of the parliament thus pronounces the gratitude of the subject; le prelats, seigneurs, et commons, en ce present parliament assemblies, aw atom de tout vous autres subjects, remercient tres hamblement votre majesté: et prient a Diew vous donner en santé, bonne vie et longue ; “the prelates, lords, and commons, in this present parliament assembled, in the name of all your other subjects, most humbly thank your majesty, and pray to God to grant you in health and wealth long to live.” 2. By the statute 33 Hen. VIII, c. 21. the king may give his assent by letters patent under his great seal signed with his hand, and notified, in his absence to both houses assembled together in the high house, by commissioners consisting of certain peers, named in the letters. And, when the bill has received the royal assent in either of these ways, it is then, and not before, a statute or act of parliament. This statute or act is placed among the records of the king- ‘dom ; there needing no formal promulgation to give it the force of a law, as was necessary by the civil law with regard to the emperor's edicts; because every man in England is, in judg- ment of law, party to the making of an act of parliament, being present thereat by his representatives. However, copies thereof are usually printed at the king's press, for the information of the whole land. An act of parliament thus made, is the exer- cise of the highest authority that this kingdom acknowledges upon earth. It hath power to bind every subject in the land, and the dominions, thereunto belonging; nay, even the king himself, if particularly named therein. And it cannot be altered, amended, dispensed with, suspended, or repealed, but in the same forms, and by the same authority of parliament; for it is a maxim in law, that it requires the same strength to dissolve as to create an obligation. ; . Such is the parliament of Great Britain: the source and guardian of our liberties and properties, the strong cement which binds the foundation and superstructure of our govern- ment, and the wisely concerted balance, maintaining an equal poise, that no one part of the three estates overpower or dis- tress either of the other. - lant or smaller yards, perfection about October. PARLIAMENT Heel, the causing a ship to ineline a little on one side, so as to clean the upper part of her bottom on the ration is called boot-topping. ... * * . PARODY, a poetical pleasantry, consisting in applying the verses written on one subject, by way of ridicule, to another; other, and cover it with fresh composition, which latter ope- observe, as nearly as possible, the same rhymes, words, and cadences. - - PAROLE, a term signifying any thing done verbally, or by word of mouth, in contradistinction to what is written; thus, an agreement may be by parole. Evidence also may be divided into parole evidence and written evidence. A parole release is good to discharge a debt by simple contract, 2 Show, 417. The holder of a bill of exchange may authorize another to indorse his name upon it. . . . PARREL, a machine used to fasten the sail-yards of a ship to the mast, in such manner as that they may be easily hoisted and lowered thereon ; there are four different kinds of parrels, viz. Parrel Rope, is formed of a single rope well served, and furnished with an eye at each end; this being passed round the yard is seized fast on, the two ends are passed round the after part of the mast, and one of them being brought under and the other over the yard, the two eyes are lashed together with a piece of spun yarn; this is seldom used but for the top gal- Parrel with Ribs and Trucks, is formed by passing the two parts of the parrel rope through the two holes in the ribs, observing that between every two ribs is strung a truck on each part of the rope. See the articles RIB and TRUck. The ends of the parrel rope are made fast with seizings, these are chiefly used on the top-sail yards. Parrel with Trucks, is composed of a single rope passing through a number of trucks sufficient to embrace the mast; these are prin- cipally used for the cheeks of a gaff. Truss PARREL, is formed by fixing a rope upon the middle of the yard, which, passing at the back of the mast, is reeved through an iron thimble, splieed into another rope, (also fastened upon the yard,) and communicates with a tackle reaching to the deck, whereby it may be occasionally slackened or straitened; ships of war gene- rally have two of these, one leading from each side, and they are peculiar to the lower yards. - - PARSLEY. The uses of parsley, in cookery, both for sauce and garnish, are numerous and well known. It is, however, poisonous to several kinds of birds; and, although so common- ly used at table, facts have been adduced, from which it would appear, that in some constitutions it occasions epilepsy, or at least aggravates the fits in those who are subject to that dis- ease. Inflammation in the eyes has also been attributed to the use of it. Parsley is eaten with great avidity by sheep, and has been recommended for use, in several diseases of those animals, as well as in some diseases of horses. Both the roots and seed are employed in medicine. The former have a sweet- ish taste, aceompanied with a slight warmth, and a flavour somewhat resembling that of the carrot; the latter are warm and aromatic. Parsley is an annual plant, a native of Sardi- nia, and propagated by seed, which is usually sown about the month of March. - - PARSNIPS, are well-known edible roots, which are propa- gated by seed sown in February or March, and the roots are in These, besides their use as a vegeta- ble for the table, are of great value for the feeding of cattle, horses, sheep, and hogs. Land in Guernsey, which lets for £7 an acre, is sown with parsnips to feed cattle : and the milk of the cows so fed is not only richer than it would otherwise be, but yields butter of fine saffron colour and excellent taste. If washed clean and sliced among bran, horses eagerly devour parsnips, and thrive well, though there is a notion that they are thereby subject to become blind. They fatten sheep and oxen in a short time; and for pigs they are at least equal if not su- perior to carrots. As food for mankind, they are considered extremely nutritive, and may with great advantage be kept on board ships for long voyages. It is, however, said that they should not be dug up for use in the spring, because, at that season, the nutritive juices' rising upward to produce the seed, they are then unwholesome. Parsnips abound in saccharine juice; and various experiments have in vain been made with P A R. P A R DICTIONARY OF MECHANICAL SCIENCE. a view to extract sugar from them. In some parts of Ireland they are used instead of malt in brewing: and, when properly fermented, afford an agreeable beverage. The seeds are said in some cases to have proved an efficacious remedy in inter- mitted fevers. PARSON, signifies the incumbent of a church. He is in himself a body corporate, in order to protect and defend the rights of the church by a perpetual succession. When a parson is instituted and inducted into a rectory, he is then, and not before, in full and complete possession. 1 Black. 391. PART, in Music, the name of each of the melodies of any harmonic composition, and which, when performed, in union, form its harmony. Four is the fewest number of parts with which the chords necessary to elaborate harmony, can be com- pietely filled. PARTERRE, in Gardening, a level division of ground, which, for the most part faces the south and best front of a house; and is generally furnished with evergreens, flowers, &c. PARTICLE, the minute part of a body, or an assemblage of several atoms of which natural bodies are composed. This term is frequently used as synonymous with atom, corpuscule, and molacule, but sometimes it is distinguished from them. PARTIES, in Law, signify the persons that are named in a deed or fine, viz. those that made the deed, or levied the fine, and also those to whom the same was made or levied. PARTING, in Chemistry and Metallurgy, is an operation by which gold and silver are separated from each other. In this sense it is the same with refining metals, or obtaining them in a pure state. cause they are capable of withstanding the action of very strong heat. All other metals are reduced to the state of oxides when subject to fire with access of air. Gold and silver may therefore be purified from baser metals, by keeping them melted till the alloy be destroyed. But this process is tedious and expensive, from the great consumption of fuel. A shorter and more ad- vantageous method of refining gold and silver has been disco- wered. A certain quantity of lead is put into the crucible with the alloy of gold and silver, the whole is exposed to the action of the fire; and the lead being quickly converted by heat into an oxide, which is easily melted into a semi-vitrified and pow- erful vitrifying matter, called litharge, we have only to increase the proportion of imperfect metals, the litharge will prevent them from being so well covered and protected by the perfect metals; and, by uniting with these imperfect metals, it com- municates to them its property of being very easily oxidated. By its vitrifying and fusing property, exercised with force upon the calcined and naturally refractory parts of the other metals, it accelerates the fusion, scorification, and separation of these metals. along with it the imperfect metals. It separates from the me- tallic mass, floats upon the surface of the melted mass, and be-, comes vitrified. But as the litharge would soon cover the melted metal, and by preventing the access of air, prevent the oxidation of the remaining imperfect metals, such vessels are employed as are capable of imbibing and absorbing in their pores the melted litharge, and thus removing it out of the way. . Or, for large quantities, vessels are so constructed, that the fused litharge, besides being soaked in, may also drain off. through a channel made in the corner of the vessel. Vessels made of lixiviated wood or bone ashes, are most proper for this purpose. e These vessels are called cupels, the process itself cupellation. face. lightning. By this mark, the metal is known to be refined. Purification of Gold by Antimony-–When gold contains but a small quantity of alloy, it may be separated from the base metal by melting it in a crucible that will hold twice its quan- tity, throwing upon it, whilst in fusion, double its weight of . crude antimony (sulphuret of antimony). The crucible is then covered, and the whole kept in a state of fusion for some mi- nutes; and when the surface sparkles, it is poured into an 79. Gold and silver are called perfect metals, be- In this operation the lead is scorified, and scorifies - The cupels are flat and shallow. The furnace should be vaulted, that the heat may be reverberated upon the surface of the metal during the operation. A crust, or dark-coloured pellicle, is continually forming upon the sur- When all the imperfect metal is destroyed, and the scorification has ceased, the surface of the perfect metal is seen clean and brilliant, forming a kind of fulguration, called l | into the matrass. cornets, or to grains, rolled up spirally. inverted cone which has been previously heated and greased. By striking the cone on the ground, the metal will come out when cold. The mass consists of two substances; the upper part being the sulphur of the crude antimony, united with the impure alloy; and the lower part gold, united to some of the ‘regulus of antimony. This gold may be separated from the regulus of antimony by exposure to less heat than will melt the gold, because antimony is volatile, and dissipates in such a heat. If the gold is not sufficiently purified by this first process, re- peat it a second, and even a third time. When a part has been dissipated, more heat is required to keep the gold in fusion; the fire must therefore be increased towards the conclusion of the operation. The purification may be completed by throwing into the crucible a little crude antimony, which effectually calcines the remaining regulus of antimony. If, after these operations, the gold be deprived of its usual ductility, this may be restored by fusing it with nitre and borax. The sulphur of the antimony, though it unites with the basest metals, does not destroy them, but forms with them a scoria, from which they may be separated by treatment as an ore. Diagrams of crucibles are unneces- sary; every one knows that a crucible is shaped like a wine glass. When the quantity of silver mixed with the gold is con- siderable, they may be separated by other processes. Nitric acid, muriatic acid, and sulphur, which cannot dissolve gold, attack silver very easily ; these three agents furnish methods of separating silver from gold, and the operation is called part- ing. Parting by nitric acid being the most convenient, is almost the only one employed by goldsmiths and coiners, who call it simply parting. That performed by muriatic acid is only made by cementation, and receives the name of concentrated parting. Lastly, parting by sulphur is effected by fusion; it is called dry parting. - Parting Gold from Silver by Nitric Acid—Though-parting by nitric acid be easy, it cannot succeed exactly, unless we at- tend to some essential circumstances. The gold and silver must be in a proper proportion; for if the gold be in too great a quan- tity, it would cover the silver, and guard it from the action of the acid; therefore when assayers know not the proportions of gold to silver in the mass, they rub the mass on a touch-stone of black basaltes, so as to leave a mark upon it; they then make similar marks with their proof-needles, (needles composed of gold and silver alloyed in graduated proportions,) and by comparing the colour of the several marks, they discover the probable scale of admixture. If the trial shews that in a given mass the silver is not to the gold as three to one, it will not serve for the operation of parting by aqua-fortis, and the quan- tity of silver necessary to make an alloy of that proportion must be added. This operation is called quartation, becauso the gold is reduced to a fourth of the whole mass. No inconve- nience arises from the quantity of silver being too great, except a waste of aqua-fortis. The nitric acid, or aqua-fortis, employed, must be pure, and free from sulphuric and muriatic acids. Its purity must therefore be ascertained; and if this be found net sufficient, the acid must be purified by nitrate of silver. If the purity of the mitric acid were not attended to, a great quantity of silver proportionable to these two foreign acids, would be separated during the solution : and this portion of silver con- verted by these acids to sulphate of silver, and to muriate of silver, would remain mingled with the gold. When the metal- lic mass is properly alloyed, it is to be reduced to plates called These are put into a matrass, and upon them there is poured a quantity of aqua- fortis, whose weight is to that of silver as three to two ; and as the nitric acid employed for this operation is weak, the solu- tion is at first assisted by the heat of a sand bath, on which the matrass is placed. When no further mark of solution appears, the aqua-fortis charged with silver is decanted. Fresh nitric acid, stronger than the former, but in less quantity, is poured This is boiled in the remaining mass, and decanted as the former. Aqua-fortis must be boiled a third time on the remaining gold, that all the silver be dissolved. The gold then washed with boiling water, is very pure, if the operation has been performed with due attention. It is called, gold of parting. .. - The silver disolved in aqua-fortis may be separated by distil- lation. In this case all the aqua-fortis is recovered pure, and fit 9 L 774 P. A. R. P A R. DICTIONARY OF MECHANICAL SCIENCE. for another parting. Or it may be precipitated by some sub- stance having a greater affinity than this metal with nitric acid. In the ascent, copper is generally employed for this purpose. The solution of silver is put into copper vessels. The aqua- fortis dissolves the copper, and the silver precipitates; the new solution being decanted, is then a solution of copper. The precipitate is well washed, and melted into an ingot, called parted silvér. When this silver has been obtained from a mass which had been refined by lead, and when it has been well washed from the solution of copper, it is very pure. Or the silver may be separated from the nitric acid by adding to it muriatic acid, with which it forms muriate of silver. Muriate of silver may be decomposed by mixing it with soda, and ex- posing it to a sufficient heat in a crucible; by this means the soda unites to the muriatic acid, and sets the silver free. Verditer.—The refiners frequently employ this solution of copper obtained in the process of parting, for making verditer; which is prepared by adding quick lime to the solution: a pre- cipitate takes place, which is the blue pigment known by the name of verditer. - - * - - Parting Gold from Silver by Cementation.—This is also called concentration, when the quantity of gold is so great to that of the silver, as to render it a difficult task by aqua-fortis. The mix- ed metal to be cemented is reduced to plates as thin as small pieces of money. At the bottom of the crucible, or melting pot, is laid a stratum of cement, composed of four parts of brick dust, one part of green copperas (sulphate of iron) calcined to redness, and one part of common salt, about the thickness of a finger in depth. Upon this stratum, a layer of plates of the metal is placed, and then another stratum of cement, and so on till the crucible is filled. It is now placed in a furnace, or oven (after a top has been luted on the crucible), and exposed for twenty-four hours, till it becomes red-hot, but not melted. The fire is now left to go out, and the metal to cool, that it may be separated from the cement, and boiled repeatedly in pure wa- ter. This gold is afterwards tried on a touch-stone; and if not sufficiently purified, the process is performed a second time. By the above method, we see how powerfully silver is dissolved by marine acid, when in a state of subtile vapour, that has been disengaged from the common salt of the cement. Nitre may be used instead of common salt, as the nitrous acid readily dissolves silver; but the mixing of common salt and nitre together is highly injudicious, because the joint acids are liable to dissolve some of the gold with the silver. Whatever silver has been separated, will now remain in the cement: but it may be freel from this by lead, in the method described in cupellation. - . . . Parting Gold from Silver in the Dry Way.—This, called also parting by fusion, is performed by means of sulphur, which has the property of uniting easily with silver, while it does not at- tack gold. This dry parting, is troublesome and expensive, and is not undertaken but when the silver far exceeds the gold, because sulphur will not separate it so easily as aqua-fortis, and will therefore require a further application to cupellation and solution. Refining Silver by Nitre.-The principle of this operation is founded on the property of nitre to oxydate very powerfully all base metals; whereas the precious metals are not affected by it. For as the metallic oxides and glasses remain not united with reguline metals, and as these latter, when in fusion, sink to the bottom on account of their great specific gravity, they may be easily, parted from the scoria. The silver to be purified by nitre is first granulated, then mixed with a fourth part of its weight of dry nitre, an eighth part of potash, and a little common glass, all in powder. This mixture is put into a crucible, two- thirds full. The crucible is covered with a smaller crucible in- verted, in the bottom of which a small hole has been made. Both are luted, and placed in a furnace capable of drawing air to make the fire intense enough to melt the silver. Then into the furnace charcoal is put to such a height, that only the top of the inverted crucible shall be uncovered. The coal is then kindled, and the vessels made moderately red, and a hot coal put upon the small hole in the bottom of the inverted crucible. If a shining light be observed round this coal, and a slight hissing noise at the same time heard, the operation proceeds well. The Fre is now sustained at the same degree till these appearances + cease, when it is increased, so that the silver be well melted, and then the crucibles are taken out of the furnace. The large crucible is broken when it is cold, and the silver will he found at the bottom covered with green alkaline scoria. . Some silver is apt to be lost in this operation, by the swelling and detonat- ing of the nitre, which often forces it through the hole in the upper crucible, unless great care be used; this method has, how- ever, its advantages, being more expeditious than cupellation. Separating Silver from Copper by Eliquation.—When in a large way, it is desired to separate a small quantity of silver from much copper with which it is alloyed, the process called eliquation is resorted to. The operation depends on the nearer affinity of silver with lead than with copper: hence it fuses, and combines with lead at a degree of heat in which copper does not fuse. - - - Whitening Silver by Boiling.—The whitening of silver by boil. ing is one of the methods of parting copper from silver in the humid way... The silver wrought in any shape is first ignited to redness, then boiled in a ley of muriate of soda and acidulous tartrate of potash, and by so doing the copper is removed from the surface, and the silver receives a whiter appearance. Precipitating Silver by Copper.—Copper has a much greater affinity with oxygen than silver; hence the silver is precipitated from its solutions as a fine silver dust, by metallic copper. This likewise affords a means of discovering what portion of silver may be contained in an alloy of silver and copper. A quantity of the mixture determined by weight is dissolved in nitric acid; the solution is diluted with filtered water, and a plate of copper hung in it, till no more precipitate. The weight of the precipitate, when edulcorated, is then compared with that of the whole alloyed metal put to trial. This silver dust, well washed, and mixed with gum water, is used in water painting. Separating Silver from Copper by an Alkaline Sulphuret. The affinity of copper with sulphur is stronger than that of silver; hence liver of sulphur (sulphuret of potash) has been proposed as an expedient to free silver from copper; for if silver con- taining copper be fused with alkaline sulphuret, the base metal will combine with the latter, and be converted into scoria floating on the silver. - - " . Keir's Mode of Separating Silver from Copper.—A compound acid that will act exclusively upon silver, is made by dissolving one pound of nitrate of potash (common nitre or saltpetre), in eight or ten pounds of sulphuric acid (oil of vitriol), or by mix- ing sulphuric and nitric acids. This acid dissolves silver easily, while it will not attack copper, iron, lead, gold, or platina. These properties have rendered it capable of a very useful application in the arts. Among the manufactures at Birming- ham, that of making vessels of silver, plated on copper, is a very considerable orie: and the method of effecting the sepa- ration of silver and copper, by means of the above mentioned compound of sulphuric acid and nitre is now commonly prac- tised by the manufacturers at Birmingham, and is much more economical, and much easier executed, than any method pre- viously practised ; nothing more is necessary than to put the pieces of plated metal into a glazed earthen pan, pour upon them some of the acid liquor, stir them about, that the surfaces may be frequently exposed to fresh liquor, and assist the action by a gentle heat, from 100° to 2009 of Fahrenheit's thermome- ter. When the liquor is nearly saturated, the silver is preci- pitated from it by common salt, forming muriate of silver, or luna cornea, easily reducible to a metallic state, by melting it in a crucible with a sufficient quantity of potash; and lastly, by refining the melted silver, if necessary, with a little nitre thrown upon it. In this manner the silver will be obtained sufficiently pure, and the copper will remain unchanged. Else the silver may be precipitated in its metallic state, by adding to the solution of silver a few of the pieces of copper, and a sufficient quantity of water to enable the liquor to act upon the copper. A Method of obtaining Gold in a Pure State.—Perfectly pure gold is obtained by dissolving the gold of commerce in nitro- muriatic acid, and precipitating the metal, by adding a weak solution of sulphate, of iron. The precipitate, after being well washed and dried, is pure gold. - . . " - A Method of obtaining Silver in a Pure State.—Dissolve the silver of commerce in nitric acid, and add to it some muriatie acid; a 'white curdy precipitate, called muriate of silver, will P A S P A S 775 DICTIONARY OF MECHANICAL SCIENCE. be formed. To reduce this to the metallic state, mix one part of it with three of soda, expose the whole to a white heat, and . when the mixture is well fused, suffer it to cool; then break the crucible, and separate the pure silver from the muriate of soda which has been formed. PARTING, the state of being driven from the anchors, by mon law, or custom, among coheirs or parceners, where there are two at the least. . . . . PARTNER. If there are several joint partners, and a per- son has dealings generally with one of them in matters con- cerning their joint trade, whereby a debt becomes due to the said person, it shall charge them jointly, and the survivors of them; but if the person only dealt with one of the partners. upon a separate account, in that case the debt shall only affect that partner and his executors. If one or more of the joint traders become bankrupt, his or their proportions are only assignable by the commissioners, to be held in common with the rest who are not bankrupts. If one of two part- ners become a bankrupt, the commissioners cannot meddle with the interest of the other, for it is not affected with the bankruptcy of his companion. ners, is payment to them all. • * PARTNERS, in Naval matters, pieces of planks nailed round the several scuttles or holes in a ship’s decks, wherein are con- tained the masts and capstans; they are used to strengthen the deck where it is weakened by those breaches, but particularly to support it when the mast leans against it. Partners, is also a name given to the scuttles themselves. , - PARTNERSHIP, a contract among two or more persons to carry on a certain business, at their joint expenses, and share the gain or loss which arises from it. All debts con- Payment to one of the part- tracted under the firm of a company are binding on the whole of the partners, though the money was borrowed by one of them for his own private use, without the consent of the rest. When a partner in a company becomes insolvent, the company is not bound for his debts beyond the extent of his share. Partnership is dissolved by the death of a partner; yet where there are more than two, it may be renewed by agreement. PART-OWNERS, are partners interested, and possessed of , certain shares in a ship. Owners are tenants in common with each other; but one or more. joint-owners refusing to contri- bute their quota to the outfit of the vessel, cannot prevent her from going, to sea against the consent of the majority of the owners, who, giving security in the Admiralty, may freight the ship at their own exclusive risk, by which the smaller dissen- tient number of owners will be excluded at once from any share, either in the risk or in the profits. PARUS, or TITMOUSE, in Ornithology, a genus belonging to the order passeres, of which there are fourteen species. PASCAL, BLAIse, a very excellent French mathematician and philosopher, was born at Clermont, in Auvergne, in 1623. He discovered very early an extraordinary genius for mathe- matical and philosophical inquiries, and is said to have formed a system of geometry, at the age of twelve years, without having seen any work on the subject, these having been care- fully kept from him by his father, lest they should divert him from his literary pursuits. PASQUIN, a mutilated statue at Rome, in a corner of the palace of the Ursini; it takes its name from a cobbler of that city, called Pasquin, famous for his sneers and gibes, and who diverted himself with passing his jokes on all the people who went through that street. t PASS, or PASSPORT, a permission granted by any state to navigate in some particular sea without hinderance or molest- ation ; it contains the name of the vessel and that of her master, together with her tonnage, and the number of her crew, certi- fying that she belongs to the subjects of a particular state, and requiring all persons at peace with that state to suffer her to proceed in her voyage without interruption. PASS, a. strait, difficult, and narrow passage, which shuts up the entrance into a country. The first care of the general of an army is, to seize the passes of the oountry into which he would carry the war, to fortify them, and take care that they are well guarded. - . - PAss, or Passade, in Fencing, an advance or leap forward upon an enemy. Of these there are several kinds; as, passes | within, above, beneath, to the right, the left, and passes under the line, &c. - PAss Parole, a command given, which passes from mouth to : mouth along the line of a regiment or army. breaking the cables through the violence of the wind, waves, &c. PARTITION, is a dividing of lands descended by the com- PASSAGE, or PAsso, any phrase, or short portion of any air, or other composition. Every member of a strain or move- ment is a passage. . . . . . . . . PASSAGE BoAT, a small vessel, employed in carrying sons or luggage from one port to another. PAss AGE, Birds of See MIGRATION and ORNIthology. PASSAGIO, (Italian,) a succession of sounds so connected in their melody and expression, as to form a member or phrase in the composition. PASSANT, in Heraldry, a term applied to a lion or other animal, in a shield, appearing to walk leisurely. PASSAREE, a rope to confine the tacks towards the ship when she is going large in light breezes; it is, however, very rarely used. * - - PASSERES, in Natural History, the sixth order of birds according to the Linnaean system. They live chiefly in trees and hedges, are monogamous, vocal, and feed the young by thrusting the food down their throats. PASSIFLORA, or PAssion Flower, a genus of plants belonging to the gynandria class, and in the natural method ranking under the 34th order, cucurbitaceae. - PASSPORT, or PAss, a license or writing obtained from a prince or governor, granting liberty and safe-conduct to pass through his territories without molestation. Passport also signifies a license obtained for importing contraband goods, or for exporting and importing merchandise without paying the duties; these last licenses are always given to ambassadors and other public ministers for their baggage, equipage, &c. PASTE. Imitations of genus are so called. Such substances are selected, to be fused together, as will produce an artificial glass, resembling in appearance the gem intended, and suffi- ciently hard and beautiful. The art has been brought to such perfection, that it requires a very close inspection of the skilful to be able to distinguish the real from the apparent. The art is much encouraged, not only by the vain, who are unable even to procure real gems, but also to replace for a time the diamonds of such persons as find it convenient to procure a temporary loan by pledging their jewels. Silex, borax, red oxide of lead, potass, and sometimes arsenic, are the base of all artificial stomes. The fusion should be kept up moderately twenty-four hours together. We shall close this article with the following Description of a Furnace constructed for Lord Bute by Mr. Peter Woulfe, for Experiments on Pastes, or Coloured Glasses.—The furnace, of which we have given a vertical, and horizontal section, (in plate Lord Bute's Furnace, &c.) is a copy of a drawing in a manuscript book of experiments and memo- randums, in the hand-writing of Mr. Woulfe, (the contriver of the apparatus that goes by his name,) who gives the following description of it:—In this furnace, which is drawn on a scale of one-sixteenth of an inch to the inch, two hundred experiments on the formation of coloured pastes or glasses may be made at once. In the drawing, where the same letters occur in different sections, they refer to the same parts of the furnace. Fig A, is a vertical section of the furnace ; a, the ash pit, or air hole, which opens on the outside of the house, and has an iron door with a register in it; b, the grate and fireplace; c c, the first chamber, for one circular row of large crucibles, placed on the floor c c ; d. d, the second chamber or floor, for two rows of crucibles; e e, the third chamber, for two rows of crucibles: f, the fourth chamber, for tests or crucibles; g, h, ś, k, doors opening into the four chambers, each of which has three doors: see the same letters in the horizontal sections BCDE, l, the door of the furnace. m. m. m. m. m., the flue in the building, which rises' three stories high. B is a horizontal section of the first cham- ber; cc, the floor or circular shelf on which the crucibles are placed ; g g g, three doors or openings. C, a horizontal section of the second chamber; d d, the floor or shelf; h h h, the doors. Fig. D, a section of the third chamber; shewing its shelf or floor e e, and its three doors i i i. Fig. E, section of the fourth per- or upper chamber, in which f is the floor, and kk k the three 776 P A V P E A DICTIONARY OF MECHANICAL SCIENCE. doors for putting in, or taking out, tests or crucibles. . A shil- ling put into a red-hot test in this chamber, melted in one minute and a half. The front of the furnace is at the side answering to the middlemost of the three doors on the respec- tive floors, viz. the side marked l g h i k, in fig. A. The best way of understanding the use of such things, is by visiting the workshops of artists employed in the manufacture of artificial sheets of paper pasted together. The chief use of pasteboard is in binding books, making letter-cases, &c. See PAPER. PASTORAL, in general, something that relates to shep- herds; hence we say, pastoral life, manners, poetry, &c. The origin of poetry is ascribed to that age which succeeded the creation of the world; and as the keeping of flocks seem to have been the first employment of mankind, the most ancient enumerates eight species. PASTURE, is generally any place where cattle may feed, and in law, is mostly applied to a common of pasture, or right: sort of poetry was probably pastoral. of feeding cattle on certain waste lands. PATEE, or PATTee, in Heraldry, a cross, small in the centre, and widening to the extremes, which are very broad. PATELLA, or LIMP et, a genus of insects belonging to the order vermes testacea. . They are always attached to some Their. summit is sometimes acute, sometimes. hard body. . obtuse, flatted, turned back, or perforated. PATENT, in general, denotes something that stands open or expanded; thus, a leaf is said to be patent when it stands. almost at right angles with the stalk. PATENT, or Letters Patent, are writings sealed with the great seal of England, by which a man is authorized to do, or to: They are so. : called on account of their forin, being open, with their seal affixed, ready to be exhibited for the confirmation of the autho- rity delegated by them. Letters patent, for new inventions, are obtained by petition to the crown: they go through many enjoy, any thing which of himself, he could not. offices, and are liable to opposition, on account of the want of novelty, &c. and if obtained, and it can be proved that the invention was not new, or had been made public previously to the granting the patent, they may be set aside. A patent at the lowest cost, and when no opposition is given to it, will, for fees of office, specification, &c. cost for the three branches of the United Kingdom, three hundred pounds. . PATHOLOGY, that part of medicine which explains the symptoms of diseases. - - - PATROL, in war, a round or march made by the guards, or watch, in the night-time, to observe what passes in the streets, and to secure the peace and tranquillity of a city or camp. The patrol generally consists of a body of five or six men, detached from a body on guard, and commanded by a sergeant. , PATRON, in the canon and common law, is a person, who having the advowson of a parsonage, vicarage, or the like spi- ritual promotion, belonging to his manor, has, on that account, the gift and disposition of the benefice, and may present to it whenever it becomes vacant. * • . . . - PATRONYMIC, among Grammarians, is applied to such names of men and women as are derived from those of parents' or ancestors. - - PAUL, a short bar of wood or iron, fixed close to the cap- stan or windlass of a ship, to prevent those engines from rolling back or giving way, when they are charged with any great effort. Paul Bits, are pieces of timber fixed perpendicularly before the windlass, near the middle of it, and serving as sup- ports to the pauls which are pinned into them. . .” * PAULicſANs, Christians of the seventh century, disciples of one Constantine, a native of Armenia, and a favourer of the errors of Manes. - .. - PAUPER. A person receiving public charity. PAUSE, in Music, a mark or character, consisting of a curve drawn over a dot, and signifying that the note or the rest, over which it is placed, is to be continued beyond the regular time. PAVEMENT, a layer of stone or other matter, serving to cover and strengthen the ground of divers places for the more commodious walking on. In London the pavement for coach ways is chiefly a kind of granite from Scotland; and on the footpath Yorkshire paving is used; the kirbstone is usually of ! S . PASTEBOARD, a kind of thick paper, formed of several actual service. more esteemed than others. - | usually propagated is by a process usually termed budding, or grafting upon the stock of some other tree; and by this process Scotch granite; courts, stables, kitchens, hałls, churches, &c are paved usually with tiles, bricks, flags, or fire stones; and sometimes with a kind of freestone and rag stone. In France, the public roads, streets, courts, &c. are paved with gres, a kind of freestone. In Venice, the streets, &c. are paved with brick; churches sometimes with marble, and sometimes with Mosiac work. In Amsterdam, and the chief cities of Holland, they call their brick pavement, the burgomasters’ pavement, to distinguish it from the stone or flint pavement, which is usually in the middle of the street, serving for the passage of their horses, carts, coaches, and other carriages; the brick borders being designed for the passage of people on foot. - PAVO, the Peacock, in Ornithology, a genus belonging to the order of gallinae. The head is covered with feathers which bend backwards; the feathers of the tail. are very long, and beautifully variegated with eyes of different colours. Latham These birds feed almost solely on insects and grain. They prefer elevated situations for roosting, choosing the tops of houses and the highest trees for this pur- pose. They were considered as luxuries for the table by the Romans, and the young ones are now regarded as a delicacy. Their voice is harsh and dissonant, and in perfect contrast to that beauty exhibited by their plumage, which, in the language of Buffon, “seems to combine all that delights the eye in the soft and delicate tints of the finest flowers, all that dazzles in the sparkling Justre of the gem, and all that astonishes in the grand display of the rainbow.” - - PAVO ET INDUS, the Peacock and Indian, a constellation situated on the Antarctic circle, contains twenty-six stars, of which one is of the 2nd magnitude, three of the 3d, and four of the 4th. The brilliant a is made of the eye of the proud bird. It has 20 ho. 11' 30" right ascension in Time, (Ann. War. 4".84,) and 57° 17'41". S. declination, (Ann. War. 10”.72.) - PAWN, a pledge lodged for the security of the payment of a sum of money borrowed. : PAY, To, as a naval term, implies to daub or anoint the surface of any body, in order to preserve it from the injuries of the water, weather, &c. To Pay a Vessel's Bottom, to cover it with a composition of tallow, sulphur, rosin, &c. - PAYING OFF, the movement by which a ship's head falls to leeward, particularly when, by neglect of the helmsman, she had inclined to windward of her course, so as to make the head sails shiver in the wind. Paying off, also implies the payment of the ship's officers and crew, and the discharge of the ship from Paying out, or Paying away, the act of slack- ening a cable or other rope, so as to let it run out of the vessel. PAYMENT, is the consideration or purchase-money for goods, and may be made by the buyer giving to the seller the price agreed upon, either by bill or note, or by money. - PEACE, in Law, signifies a quiet and harmless behaviour towards the king and his people. . . - PEACE, Justices of. See Justice of THE PEACE. PEACH. This rich and delicious fruit is highly and deserv- edly esteemed at table, as an article in our deserts; and when ripe and fresh, is grateful and wholesome, seldom disagreeing with the stomach, unless this organ be not in a healthy state, or the fruit has been eaten to excess. When preserved in wine, brandy, or sugar, it loses its good properties. The kernels yield a salubrious bitter. The flowers, which are very beauti- ful, and appear only in the spring, emit an agreeable odour, have a bitterish taste, and, including the calyx as well as the corolla, are used for medical purposes. The leaves are occa- sionally employed in cookery, but they ought not to be used without great caution, on account of their injurious properties. There are many varieties of the peach, some of which are much The mode in which the trees are those of any favourite kind may be exactly obtained. - PEAK, a name given to the upper corner of those sails which are extended by a gaff, or by a yard which crosses the mast obliquely, as the mizzen yard of a ship, the main yard of a by- lander, &c. The upper extremity of these yards and gaffs are also denominated the peak. . . PeAK Haliards, are the ropes or tackles by which the outer end of a gaſf is hoisted, as opposed to the throat halliards. P E. A. .P. E. E. 777 , DICTIONARY OF MECHANICAL SCIENCE. ... PEAR, The CoMMon, is a well-known garden fruit, derived from an English stock, (the wild pear tree,) which grows in hedges and thickets in Somersetshire and Sussex. It would be an endless task to describe the different known varieties of the cultivated pear. and others, as the iron pear, are so hard and disagreeable to the taste, as to be absolutely unfit to eat. Pears are chiefly used in desserts; and one or two of the kinds are stewed with sugar, baked, or preserved in syrup. The fermented juice of pears is called perry, and is prepared nearly in the same man- The greatest quantities of ner as that of apples is for cider. * perry are made in Worcestershire and Herefordshire. The Squash, the Oldfield, and the Barland perry, are esteemed the best. Many of the dealers in Champaigne wine are said to use perry to a great extent in the adulteration of it; and, indeed, really good perry is little inferior in flavour or quality to Champaigne. Of the wood of the pear tree, which is light, smooth, compact, and of a yellowish colour, carpenters’ and joiners' tools are usually made, as well as the common kinds of flat rulers, and measuring scales. It is also used for picture frames that are to be stained black. The leaves impart a yel- low die, and are sometimes employed to communicate a green colour to blue cloth. - - - PEARLS, are a calculus or morbid concretion, formed in consequence of some external injury which the muscle or shell- fish receives that produces it, particularly from the operations of certain minute worms which occasionally bore even quite through to the animal. The pearls are formed in the inside on these places. Hence it is easy to ascertain, by the inspection of the outside only, whether a shell is likely to contain pearls. If it be quite smooth, without cavity, perforation, or callosity, it may with certainty be pronounced to contain none. If, on the contrary the shell be pierced or indented by worms, there will always be found either pearls, or the embryos of pearls. It is possible, by artificial perforation of the shells, to cause the forma- tion of these substances. The process which has been chiefly recommended, is to drill a small hole through the shell, and to fill it up with a piece of brass wire, riveting this on the outside like the head of a mail; and the part of the wire which pierces the interior shining coat of the shell, will, it is said, become co- vered with a pearl. As to the value of British pearls, some have been found of size so large as to be sold for £20 each, and upwards; and £80 was once offered and refused for one of them. It is reported in Wales, that a pearl from the river Conway, which was presented to the queen of Charles the Second, was afterwards placed in the regal crown. - The Oriental PeARL Muscle to which we are indebted for nearly all the pearls of commerce, has a flattened and some- what circular shell, about eight inches in diameter; the part near the hinge bent or transverse, and imbricated (or covered like slates on a house) with several coats, which are toothed at the edges. - }our, others are chesnut or reddish, with white stripes or marks; and others whitish with green marks. These shells are found hoth in the American and Indian seas. fisheries are of the casts of Hindoostan and Ceylon. They usu- ally commence about the month of March, and occupy many boats and a great number of hands. Each boat has generally twenty-one men, of whom one is the captain, who acts as pilot; ten row and assist the divers, and the remainder are divers, who go down into the sea alternately by five at a time. The king of Persia has a pear-shaped pearl so large and pure as to have been valued at £110,000 sterling. The largest round pearl that has been known, belongs to the Great Mogul, and is about two-thirds of an inch in diameter. Pearls from the fishery of Ceylon are considered more: valuable in England than those from any other part of the world. . The smaller kinds are called seed or dust pearls, and are of comparatively small value, being sold by the ounce, to be converted into powder. " . To make Artificial PEARLs, take the blay or bleak fish, com- mon in the Thames, scrape off the silvery scales from the belly; wash and rub these in water. Then suffer this water to settie, and a sediment will be found, of an oily consistence. A little of this is to be dropped into a hollow glass bead of a bluish tint, and shaken about so as to cover all the internal surface; after - 80. Some of these are very large, and others extremely small ; some have a rich and luscious flavour, Some of the shells are externally of sea-green co- The principal pearl this, the bead is filled up with melted white wax, to give it soli- dity and weight. - - To Whitén discoloured PEARLs.-Soak them in hot water, in which some bran with a little tartar and alum have been boiled, rub them gently between the hands, which may be continued until the water grows cold, or until the object is effected, when they may be rinsed in lukewarm water, and laid on writing paper in a dark place to cool. - PEAT, is one of the most important productions of alluvial ground; it may be regarded as belonging more properly to the vegetable than to the mineral kingdom. Peat formerly covered extensive tracts in England, but is disappearing before the ge- nius of agricultural improvement, which has no where produced more important effects than in the conversion of the black and barren peat moors of the northern counties into valuable land, covered with luxuriant herbage, and depastured by numerous flocks. It consists of wet spongy black earth, and decayed vegetables. - - PEBBLES, the name of a genus of fossils, "distinguished from the flints by having a variety of colours. These are defined to be stones composed of crystalline matter debased by earths of various kinds in the same species, and then subject to veins, clouds, and other variegations, usually formed by incrustation round a central nucleus, but sometimes the effect of a simple concretion ; and veined like the agates, by the disposition which the motion of the fluid they were formed in gave their different coloured substances. - PECK, an English measure, the fourth part of a bushel. PECTEN, the Scallop, a genus of shell fish, the characters of which are these : the animal is a tethys ; the shell bivalve and unequal; the hinge toothless, having a small ovated hollow. PECORA, in Natural History, the fifth order of the class Mammalia. There are eight genera, viz. Antelope, Bos, Ca- melus, Camelopardalis, Capra, Cervus, Moschus, Ovis. PECULIAR, signifies a particular parish or church that hath jurisdiction within itself for probate of wills, &c. exempt from the ordinary, and the bishop's court. The Court of Peculiars is that which deals in certain parishes, lying in several dio- ceses; which parishes are exempt from the jurisdiction of the bishops of those dioceses, and are peculiarly belonging to the archbishop of Canterbury, within whose province there are fifty-seven such peculiars. - - PEDESTAL, in Architecture, the lowest part of an order of columns, being that part which sustains the column, and serves as a foot on which it may stand erect. PEDICELLAIA, a genus of insects belonging to the order vermies mollusca. - - PEDICULUS, Louse, a genus of insects of the order aptera. PEEK, is a term used in various senses. An anchor is said to be a-peek when the ship being about to weigh, comes over her anchor, so that the cable hangs perpendicularly between the hawse and the anchor. (See the articles ANCH or and A- Peek.) Also, the bringing a ship into the above position is call- ed heaving a-peek. She is likewise said to ride a-peek when lying with her main and fore yards hoisted up, one end of her yards is brought down to the shrouds, and the other raised up on end; which is chiefly done when she lies at rest in rivers, lest other ships, falling foul of her, should break her yards. Peek is also used for the room in the hold, from the bitts forward to the stern. In this place men of war keep their powder, and merchantmen their victuals. r PEER, in general, signifies an equal, or one of the same rank and station; hence, in the acts of some councils, we find these words, “with the consent of our peers, bishops, abbots,” &c. Afterwards the same term was applied to the vassals or tenants of the same lord, who were called peers, because they were all equal in condition, and obliged to serve and attend him in his courts; and peers in fiefs, because they all held fiefs of the salue lord. The term peers is now applied to those who are impa- nelled in an inquest upon a person for convicting or acquitting him of any offence laid to his charge; and the reason why the jury is so called, is, because by the common law, and the cus- tom of this kingdom, every person is to be tried by his peers, or equals; a lord by the lords, and a commoner by commoners. P£er of the Realm, a noble lord who has a seat and vote in the house of lords, which is also called the house of peers. 9 M 778 Tº E. L. P. E. N. DICTIONARY OF MECHANICAL SCIENCE, These lords are called peers, because, though there is a dis- tinction of degrees in our nobility, yet in public actions they are equal, as in their votes in parliament, and in trying any nobleman, or other person, impeached by the commons, &c. A peer is not to be put upon any inquest, even though the cause has a relation to two peers; but in trials where any peer is either plaintiff or defendant, there must be two or more knights returned on the jury. Where a peer is defendant in a court of equity, he is not to be sworn to his answer, but it may be upon his honour, as in the trial of peers; however, when a peer is to answer to interrogatories, or to make an affidavit, or is to be £xamined as a witness, he is to be sworn. - PEERESS, a woman who is noble by descent, creation, or marriage. If a peeress by descent or creation marries a per- son under the degree of mobility she still continues noble ; but if she obtains that dignity only by marriage, she loses it on her afterwards marrying a commoner; yet by the courtesy of Eng- land she alway retains the title of her nobility. No peeress can be arrested for debt or trespass; for though, on account of their sex, peeresses cannot sit in the house of lords, yet they enjoy the privileges of peers, and therefore all peeresses by birth are to be tried by their peers. PEGASUS, one of the old constellations, and known as the fabled favourite of the Muses, is a paratanellon of Aquarius, and the zodiacal Fishes. We think this affinity is far more symbolical of the inroad of the Scythians into Egypt in the 7th century, than of the ark of Noah, before the Christian era; though it is not to be denied that the arkite and solar worship are frequently confounded in a much more extraordinary way, than the debased and slavish Romans confounded science and folly, by the deification of Antonius, whose medals, statutes, temples, city, oracles, and constellations, are well known, and still dishonour the memory of Hadrian. . PEGASUs, is also a genus of fishes, of the order nantes. PELAGIANS, a Christian sect who appeared before the lat- ter part of the fourth, or the beginning of the fifth century. They are said to have maintained, 1. That Adam was by nature mortal, and whether he had sinned or not would certainly have died. 2. That the consequences of Adam's sin were confined to his own person. 3. That new-born infants are in the same condition with Adam before the fall. 4. That the law qualified men for the kingdom of heaven, and was founded upon equal promises with the gospel. 5. That the general resurrection of the dead does not follow in virtue of our Saviour's resurrection. 6. That the grase of God is given according to our merits. 7. That this grace is not granted for the performance of every mo- ral act; the liberty of the will, and information in points of duty, being sufficient, &c. PELECANUS, the Pelican, in Natural History, a genus of birds, of the order anseres. There are thirty species, of which we shall notice the following: The great pelican, is sometimes of the weight of 25 pounds, and of the width, between the extreme points of the wings, of 15 feet; the skin between the sides of the upper mandible, is extremely dilatable, reaching more than half a foot down the neck, and capable of containing many quarts of water. This skin is often used by sailors for tobacco pouches, and has been occasionally converted into elegant ladies’ work- bags. About the Caspian and Black seas these birds are very numerous, and they are chiefly to be found in the warmer re- gions, inhabiting almost every country in Africa. They build in the small isles of lakes, far from the habitations of man.—The American pelican, is about the size of a goose; of this bird it, is reported that it will bring large supplies of food to any dis. abled and diseased companion; and that the natives of the island of Assumption, by confining one near the shore, fre- quently induce others to make these generous presents, which are fraudulently converted to the purpose of food for the island- ers.-The man-of-war bird, is small in body, but between the extremities of the wings fourteen feet in width. It is seldom seen but within the tropics, and not unfrequently is observed two hundred leagues from land. It watches the movements of fishes from a very considerable height, and pounces upon them with unfailing success, returning from its immersion with equal rapidity-The carbo, or cormorant, nearly as large as a goose, is found in many places both of the old and the new world, and is to be met with in the northern parts of this island. These birds are shy and crafty, but frequently eat to so great an excess as to induce a species of lethargy, in which they are caught by 'nets thrown over them, without their making an effort to escape. They are trained by the Chinese to fish for them. By a ring placed round their necks, they are prevented swallowing what they take, and, when their pouches are filled, they unload them, and at the command of their owners renew their divings; two will be seen combining their efforts to secure a fish too large for the management of one only. When their work is finished to the employer’s satisfaction, the birds have a full allotment of the spoil, for their reward and encouragement. In Macao, also these birds are thus domesticated, taking extreme delight in the exercise, and constituting a source of very considerable profit to their owners. They were formerly trained and used in the same manner in England; and Charles I. had an officer of his hostsehold, called master of the cormorants.—The Solañd goose, or gannet, weighs about seven pounds, and inhabits in great numbers the northern isles of this kingdom. It is migra- tory, and drawn to this country by the shoals of herrings and pilchards, whose movements it watches with the most anxious vigilance. The young birds are sold in great plenty at Edin- burgh, where they are frequently introduced before dinner as a stimulus to appetite. In St. Kilda it is supposed that up- wards of twenty thousand of these birds are taken annually. They constitute an important article of food to the inhabitants, who, to procure both the eggs and young ones, expose them- selves to the most imminent dangers on elevated and precipi- tous cliffs, and in several instances have fallen victims to the hardihood with which they have pursued their researches dur- ing the breeding season. - PELECOID, or Pelecoides, hatchet form, in Geometry, contained under the two inverted qua- drantal arcs A B and AID, and the se- micircle B C D. The area of the pele- coid is demonstrated to be equal to the square A C; and that again to the C I}}34--------------- *---------------+--------------D.-- ~ s : * s = s. . . * * * R :::::P, I *S. J. ** - C --><-ºf 'i'. - - - - - T.T."--~~~:2:* , g • J " - :----.ITT - - - - - - & ------ " " T sº º ... • T.’ g * - - -7°. • * ** - - - , , T * ~ *----, - *A* . . . . -- * * * ... -- * * * - ſº 1. - £ºs. ** *E* sº º F=-s=---------sa/. fºr- ºr " O - - - " " ' ... • * Zºº:: * * * * ~ * ~/* ----- - - - - - - - - - - --> rº------~~ Z...~" ... • * * $ & * |-ºr- -- F:---i--i- -------------------- |ji Bºrº'ſ - ~~~ * ~~~ t ! ! ! ,” * * º ſ --~~" ... * t t ſº : ,” ~ *--- i | | .** ,” J : * ,” * \ t | - * p * & !." ſ: y | .” p ! ; # * * * * * * * * * * * * * * **- - -- §: #|| | 2^ º g” - t * * | - - sº ſº 1.” . * #| | | t * | a 4-, * * * * * * * * * * * * * * * * * * * * * = ill; | - : Af, g fºlſ. Tºº" " ū ; ," | | | C * t !,’ - & | % º g ---|-- - - - - -4 A ſi. Z, s sº * * * From F draw a line to any part of the horizontal line, as to L, and draw from M a line to meet this in L. Tof draw the line fh, and to d the line id; then from h and i raise perpendiculars to intersect FL, and from the points of intersection draw the lines p l and r k; thus will be obtained the perspective outline of the cube k l fago e. If the cube had not been viewed directly opposite one of its angles, the points of distance would not on each side have coincided with the vanishing points; and the vanishing points would have been best obtained as for the Fig. 14. triangular prism, fig. 12. - The procedure for a parallelopiped, is es- sentially the same as for a cube. To put a cylinder into perspective, first proceed as for a cube, or parallelopiped; draw on the perspective of each end such an ellipse as it will admit; let the longer or conjugate axes be equal, and join the opposite extremities of these axes by two parallel lines, as shewn in fig. 14. , Having thus obtained the per- spective of the cylinder, it only remains to erase the lines which belong to the cube or ------ parallelopiped. Of Shadows, and Description of a Machine for Drawing in Per- spective.-Having now shewn the mode of putting into perspec- ..: P E R JP E R. DICTIONARY OF MECHANICAL SCIENCE: 793 tlye those elementary forms which enter into the composition of drawings of every description, we shall be obliged to be concise with the remainder of the subject. The student must be aware how much difference of position affects the visual appearance of objects, and that by a proper attention to this circumstance, the few rules which have been given may be applied to subjects of considerable complication. To acquire a knowledge of the principles of perspective, it is recommended not merely to com- pare the plates with the printed page; but to copy the dia- grams, and, for the sake of greater perspicuity, to do this on as large a scale as may be convenient. Afterwards some trea- tise especially devoted to the subject may be perused, and per- haps Brook Taylor's and Malton's may be the best; though these authors will require considerable attention, they have the merit of being sure guides. . With respect to shadows, the proper distribution of which give such life to perspective drawings, it may be useful to re- mark, that the shadow cast by any object covers the precise space which that object wouls. prêvent the eye from seeing, if the eye were in the place of the luminous body. The position, therefore, of the luminous body, must always be ascertained, and the shadow to be assigned to any object in a picture, will be a perspective view of the space which the eye would be pre- vented from seeing if in the place of the luminous body. A few experiments with a candle at night will be an easy mode of gaining a little acquaintance with this subject; it must, how- ever, be observed, that the shadow from a candle is every way larger than that part of the object which intercepts the rays; but in point of breadth, this never happens with the shadows | of the sun. The reason is, that the rays from the candle consi- derably diverge, while those from the sun, on acceunt of the immense distance of that luminary, have no perceptible devia- tion from parallelism. It must be remembered also, that strong reflections from surrounding objects will diminish the intensity of shades, and that not only the quantity of light which falls on an object, but the quantity which can be reſlected to the eye, must be considered. . . . . As it frequently happens that persons have occasion to draw the art; for the use of such, a great variety of machines have been constructed. Most of these machines are on optical prin- ciples; the camera obscura, which we have already described; is one of them, and the camera lucida is another. In praise of the latter, much has lately been said; but although it must be admitted to be a very portable and beautiful instrument, the ac- | quisition of the proper art of using it, is extremely difficult to all, and to some impossible. Its chief use will be that of affording the means of contemplating the real perspective ap- pearance of objects, and perhaps to obtain the position of a few points, but for very minute delineation it is of little value. For general use, we may venture to recommend an instrument described by Ferguson, to whom the knowledge of it was com- municated by Dr. Bevis. It has the advantage of other ma- chines in two points; it may be constructed at a small expense by any tolerably skilful artisan in wood, and the use of it will constantly tend to render the practice of perspective drawing more easy, by the manner in which it produces the measure of surfaces or angles. It will, therefore, better than most other other instruments for the same purpose, supply the want of a more extended essay. - - - Fig. 15. The machine in ques- tion is represented at figs. 15 and 16. Fig. 15 is a plan, and fig. 16 a view of it on a larger scale. The same letters refer to the corresponding parts in both figures. A BEF is an oblong board, and XY are two hinges, on which the part C. L. D is move- able. This part consists of two arches, or portions of arches, CM L, and DNL, joined together at the top L, and at the bottom to the cross-bar DC, to which one part of each hinge is fixed, and the other part to a flat board, half the length of the board A B E F, and glued to its uppermost side, The 81. drawn further out, or pushed further in, at pleasure. outer end of this bar, I, fig. 16, is fixed the upright piece H Z; in at: D, and the centre of the arch centre of the arch C. M. L' is : D N L, is at C. - - . +. Fig. 16. On the outer side of the arch D NL is ; sliding piece, N, (much like the nut of the quadrant of altitude belonging to a common globe,) which may be moved to any part of the arch between D and L ; and there is such another slider O, on the arch CM L, which may be set to any part between C and L. A thread C P N is stretched tight from the centre C to the slider N, and such another thread is stretched from the centre D to the slider O ; the ends of the threads being fastened to these centres and sliders. It is plain, therefore, that by moving the sliders on their respective arches, the intersection P of the threads may be brought to any point of the open space within those arches. - * In the groove K is a straight sliding bar I, which may be To the which is a groove for receiving the sliding piece Q. In this slider is a small hole R, for the eye to look through in using the machine; and there is a long slit in HZ, to let the hole R be seen through when the eye is placed behind it, at any height of the hole above the level of the bar I. Suppose a house, q s r. p, to be at a considerable distance º beyond the limits of the plate, to obtain a perspective represen- in perspective, who have acquired no theoretical knowledge of | plate, persp p tation of it, place the machine on a table, with the end E F, of the horizontal board A BEF towards the house, so that, when the arch DLC is set upright, the middle part of the open space (about P) within it, may be even with the house when the eye is placed at Z, and looking at the house through the small hole R; and then fix the corners of a square piece of paper with four wafers, on the surface of that half of the horizontal board which is nearest the house. To complete the arrangement of the apparatus for drawing, set the arch upright as in the figure, which it will be when it comes to the perpendicular side T, of the upright piece ST, fixed to the horizontal board behind D. Then placing the eye at Z, look through the hole R at any point of the house, as q, and move the sliders N. and O, till the intersection of the threads at P, is directly between the eye and the point q; them put down the arch flat upon the paper on the board, as at 8 t, and the intersection of the threads will be at W. Mark the point W on the paper with the dot of a black-lead pencil, and set the arch upright again as before ; then look through the hole R, and move the sliders N and O, till the intersection of the threads , comes between the eye and any other point of the house, as w; this being done, put down the arch again to the paper, and make a pencil mark thereon at the intersection of the thread as before ; obtain the point p in the same manner, and draw a line from that mark to the one at w. The line p w, thus obtained, will be a representation in true perspective, of the corner p q of the house. By thus bringing the intersection of the threads successively between the eye and other points of the outlines of the house, as rs, &c. and putting down the arch to mark the correspond- ing points, on the paper, at the intersection of the threads, then | connecting these points by straight lines, the entire perspec- tive outline of the house will be obtained. In like manner find points for the corners of the doors, windows, &c, and draw the finishing lines from point to point. The perspective drawing thus produced, may then be completed, by shading it accord- ing to the manner in which the light is observed to fall on the original. 9 Q 794 P E R. P E T DICTIONARY OF MECHANICAL SCIENCE. Great care must be taken, during the whole of the time, that the position of the machine be not shifted on the table; and to prevent such an accident, the table or support employed should be perfectly steady, and the machine fixed down upon it by screws or clamps. - It is obvious that a landscape, or any number of objects within the field of view through the arch, may be delineated, by finding a sufficient number of points, and connecting them by straight or curved lines, as they appear in the original objects. -- - The arch ought to be not less than a foot wide at the bottom, that the eye at Z may have a large field of view through it; and the eye should be then at least ten inches and a half from the intersection of the threads at P, when the arch is set upright. If the eye be nearer, the boundaries of the view, at the sides near the foot of the arch, will subtend an angle at Z of more than 60 degrees, which will not only strain the eye, but will cause the outermost parts of the drawing to have a disagreeable appearance.—To avoid this, it will be proper to draw back the sliding bar I, till Z be fourteen inches and a half distant from P; then the whole field of view through the foot-wide arch, will not subtend an angle to the eye at Z of more than 45 de- grees: which will give a more easy and pleasant view not only of the objects themselves, but of their representations upon the paper on which they are delineated. Hence, whatever may be the width of the arch, the distance of the eye from it should be in this proportion: as 12 is the width of the arch, so is 14% to the distance of the eye (at Z) from it. - If a pane of glass, previously coated with thin gum-water, and dried, be fixed in the arch, a person who looks through the hole at R, may delineate upon the glass the objects which he sees at a distance, and the delineation may be afterwards transferred to paper. By this means will be saved the trouble of putting down the arch to take the position of every point, but it will not be so easy to obtain a correct representation. Perspective Glass, in Optics, differs from a telescope in this: instead of the convex eye-glass placed behind the image, to make the rays of each pencil go parallel to the eye, there is placed a concave eye-glass as much before it; which opens the converging rays, and makes them emerge parallel to the eye. The quantity of objects taken in at one view with this instru- ment does not depend upon the breadth of the eye-glass, as in the astronomical telescope, but upon the breadth of the pupil of the eye. Reflecting perspective glasses, called by some opera- glasses, or diagonal perspectives, are so contrived that a per-, son can view any one in a public place, as the opera or play- houses, without it being possible to distinguish who it is he looks at. See OPERA GLAss. Perspective Plane, is the glass or other transparent surface, supposed to be placed between the eye and the object, perpen- dicular to the horizon. It is sometimes called the section table, or glass. PERSPIRATION, in Physiology, the excretion of a fluid through the pores of the skin, and which is usually distinguished into sensible and insensible, or perceptible and imperceptible. PERU, BALSAM of. This substance is obtained from the myroxylum peruiferum, which grows in the warm parts of South America. by boiling the twigs in water. It has the consistency of honey, a brown colour, an agreeable smell, and a hot acrid taste. PERUKE. It appears that this term was originally applied to describe a fine natural head of long hair; but whatever has been the ancient use or meaning of the word, it has now almost become obsolete, though it was for more than a century in con- stant application to those artificial heads of hair, made proba- bly at first to conceal natural or accidental baldness, but which afterwards became so ridiculously fashionable, as to be worn in preference to the most beautiful locks, absurdly shaved off the head to make room for them. - PERUVIAN BARK. See CINchoNA. The penetrative effects of Peruvian bark are thus described by M. Delpech, a French merchant of Guayra, in the Caraccas, who in 1817 had stored up large quantities of fresh cinchona, in apartments which were afterwards required for the reception of some tra- vellers as guests. These apartments contained each eight or ten thousand pounds of bark, and in consequence of its fer. treatment whatsoever. The tree is full of resin, and the balsam is obtained mentation, the heat was much greater here than in the other parts of the house, rendering the place somewhat disagreeable. One of the beds placed in these rooms, was occupied by a traveller, ill of a malignant fever: after the first day he found himself much better, though he had taken no medicine; and in a few days he felt himself quite recovered, without any medical This unexpected success induced M. Delpech to make some other trials: several persons ill of fever were placed successively in his magazine of cinchona, and they were all speedily cured, simply by the effluvia of the bark. It happened that a bale of coffee and some common French brandy were kept in the same place for some months; one of the brandy bottles happened to be uncorked, and on examination it was found to possess a slight aromatic taste, to be more tonic, and very superior to common brandy. The coffee also was much altered; when roasted it was more bitter than common coffee, and left in the mouth a taste similar to that of an infusion of bark. PETAL, among Botanists, an appellation given to the flower leaves, in opposition to the folia, or common leaves of the plant. PETARD, in the art of War, a metallic engine, somewhat resembling a high-crowned hat. Its use is in a clandestine attack to break down gates, bridges, barriers, &c. to which it is hung ; and this it does by means of the wooden plank attached to it. It is also used in countermines, to break through the enemy’s galleries, and give their mines vent. + PETERERO, or PATTERero, a small piece of ordnance used on board ships for the discharging of nails, broken iron, or par- tridge shot, on an enemy attempting to board. They are gene- rally open at the breech, and their chamber made to take out to be loaded that way instead of at the muzzle PETER-PENCE. An ancient tax of a penny on each house paid to the pope. - . . . PETEVERIA, a genus of plants belonging to the hexandria class, and in the natural method ranking under the 14th order, Holoraceae. - - PETITIO PRINCIPII, in Logic, the taking a thing for true, and drawing conclusions from it as such, when it is really false, or at least wants to be proved before any inferences can be deduced from it. . - - PETITION. No petition to the king, or to either house of parliament, for any alteration in church or state, shall be signed by above twenty persons, unless the matter thereof is approved by three justices of the peace, or the major part of the grand jury, in the county; and in London, by the lord: mayor, aldermen, and common council; nor shall any petition be presented by more than ten persons at a time. PETRIFACTION, the conversion of wood, bones, and other substances, principally animal or vegetable, into stone. But how this is effected cannot be distinctly unfolded; all that we know certainly, is that the original mass is replaced by earthy or mineral particles. Thus on the north side of the river Eske, a short distance above the paper-mill. at Penicuik, near Edin- burgh, where the strata usually accompanying the coal forma- tion of this country are exposed, a large portion of the trunk, and several roots, of a fossil tree, are visible. It rises several feet above the bed of the river, as far as the strata reaches, and the roots spread themselves in the rock. It appears as if the tree had actually vegetated on the spot where we now see it. It is, where thickest, about four feet in diameter. The strata, in which the remains of the tree stand, are slate clay, and the tree itself is sand-stone. There is sand-stone below and immediately above the slate clay, and the roots do not appear to have penetrated the lower sand-stone, to which they reach. Small portions of coal were observed where the bark existed, the form of which is distinct on the fossil. Whilst sinking a pit, in 1818, at Mr. Fenton's colliery, near Wakefield, Yorkshire, the workmen, having dug to the depth of eighty-six yards, came to a bed of coal two feet six inches thick, beneath which they found a petrified tree, or rather plant, having no branches, standing upright, but rather inclining to the east. It was six inches diameter at the top; but, as they sunk down, it increased to twelve inches, and at the depth of forty-two feet, seemed to branch out roots to another bed of coal six feet thick. The body was a gray sand-stone, coated round with a black carbonized matter one-tenth of an inch, supposed to be 9. P E T P E. T. 795 DICTIONARY OF MECHANICAL SCIENCE. its bark. A species of siliceous fossil wood was found by a sergeant of artillery, who accompanied Captain Sabine, near the top of a hill in Hare Island, on the west coast of Green- land, in latitude 70° 26'. It had been a part of the trunk of a pine tree, about four inches in diameter. The hill is in the interior of the island, about four miles from the shore, and is considerably more than 900 feet above the level of the sea. In the paper called the General Evening Post, for March the 17th, 1818, there is an account that had been then received at the Admiralty, of an interesting discovery made in the south of Africa, about twenty miles north of Cape Town. Some per- sohs, in digging, happened to strike upon what appeared a beam of timber; but, tracing it, they found a ship deeply im- bedded in the soil. A plank of it has accompanied the account of the discovery to the Admiralty. Several other ships, at dif- ferent times, and in different parts of the world, have been discovered beneath the surface of the earth. It is recorded by Fulgosas, that in the year 1462, as some men were working a mine near Berne, in Switzerland, they found a ship 100 fathoms deep in the earth, with anchors of iron, and sails of linen, and the remains of forty men. Pairre Naxis relates a like history of another such ship having been found under a very high mountain. The Jesuit Eusebius Newcombergus, in his fifth book of Natural. History, says, that near the port of Lima, in Peru, as the people were working a gold mine, they found a ship, on which were many characters very different from ours. Strabo also relates, in his first book, that the wrecks of ships have been found 375 miles from sea. Dr. Plott, in his Natural History of Staffordshire, relates a story, that the mast of a ship, with a pulley hanging to it, was found in one of the Greenland mountains. Is it to be supposed that these ships, which have been found beneath the surface of the earth, were antediluvian ships ? - r . In the parish of Motterton, in the Isle of Wight, bones, which are supposed to belong to one of the mammoths, were discovered. Several of the vertebrae, or joints of the back- bone, measure thirty-six inches in circumference: they cor- respond exactly in form, colour, and texture, with the bones of a similar kind found on the banks of the Ohio in North America. Also, in the parish of Northwood, on the north side of the island, the bones of the crocodile have recently been found by the Rev. Mr. Hughes of Newport. They seem to have belonged to an animal of that species, whose body did not exceed twelve feet in length. Their calcareous mature is not altered; but the bones of the mastodon (found on the south side of the island) contain iron. A considerable quantity of bones of a large size were lately discovered buried in the earth, in the neighbourhood of the village of Tiede, near Bruns- wick. They were examined by M. Dahne, who appears to have distinguished parts of the skeletons of five elephants. There were nine tusks among them, one of which was fourteen feet in length, another eleven, and many grinders, in which the enamel was arranged exactly as in the teeth of the African elephant. A complete head of a rhinoceros, with the horn and teeth, was also found very little altered, and likewise the horns of two kinds of stags. Mr. Dahne, in eldeavouring to account for this accumulation of bones belonging to different animals, Supposes that the animals existed in immense islands; that some great revolution of the globe inundated their habitations, and forced them to the highest spot for shelter from the waters; that, the waters still rising, they all perished together; that the perishable parts of their carcases were carried away by the waters, and that an earthy deposition soon enveloped the bones, and left them nearly in the state they are now found. Mammoths’ and elephants’ bones and tusks are found throughout Russia, and more particularly in Eastern Siberia and the Arctic marshes. The tusks are found in great quan- tities, and are collected for the sake of profit, being sold to the turners in the place of the living ivory of Africa, and the Warmer parts of Asia, to which it is not at all inferior. To- wards the end of the month of August, when the fishing season in the Lena is over, the Tungusians generally go to the peninsula of Tamut, where they employ themselves in hunting, and where the fresh fish of the sea offer them a wholesome and agreeable food. One day, their chief, Schumachof, perceived among the blocks of ice a shapeless mass, not at all resembling the large pieces of floating wood, which are commonly found there. The following year (1800) he found the carcase of a walrus (trihche- chus rosmarus.) He perceived, at the same time, that the mass. he had before seen was more disengaged from the blocks of ice, and had two projecting parts, but was still unable to make out its nature. Towards the end of the following summer (1801,) the entire side of the animal, and one of his tusks, were quite free from the ice. But the summer of 1802, which was less warm, and more windy than common, caused the mammoth to remain buried in the ice, which had scarcely melted at all. At length, towards the end of the fifth year (1803,) the ardent wishes of Schumachof were happily accomplished; for the part of the ice between the earth and mammoth having melted more rapidly than the rest, the plane of its support became inclined, and this enormous mass fell, by its own weight, on a bank of sand. In the month of March, 1804, Schumachof came to his mammoth ; and, having cut off his horns (the tusks) he ex- changed them with the merchant Bultunof for goods of the value of fifty rubles. Two years afterwards, a Mr. Adams, traversing these distant and desert regions, found the mam- moth still in the same place, but altogether mutilated. Wild beasts, such as white bears, wolves, wolverines, and foxes also, fed upon it; and the traces of their footsteps were seen around. The skeleton, almost entirely cleared of its flesh, remained whole, with the exception of one fore-leg. The spine from the head to the os coccygis, one scapula, the pelvis, and the other three extremities, were still held together by the ligaments and by parts of the skin. The head was covered with a dry skin; one of the ears, well preserved, was furnished with a tuft of hairs. Accounts from the banks of the Mississippi state, according to the Philosophical Magazine, that the mammoth has been discovered actually in existence in the western deserts of North America. According to the descriptions given of it, this colossus of the animal kingdom is not carnivorous, but lives on vegetables; more particularly on a certain spe- cies of tree, of which it eats the leaves, the bark, and even the trunk. It never lies down, and sleeps leaning for support against a tree. It has rather the shape of a wild boar than of an elephant, and is fifteen feet high. His body is covered by a hairy skin, and he has no horn. f PETROLEUM, is a fluid bitumen, of somewhat greater con- sistency than naphtha, of black, brown, or sometimes dingy green colour. By exposure to the air it assumes the consistence of tar, and is then called mineral tar. This substance exudes spontaneously from the earth, or from clefts of rocks, and is found in nearly all countries, particularly in the East Indies, Italy, France, Spain, Germany, and England. In the neigh- bourhood of Rangoon, in Pegu, there are several hundred wells of petroleum. These are of square form, and each lined with cassia wood staves. The property of the wells is in the pro- prietors of the soil, for whom they have been sunk, and are wrought. Some of the wells are of great depth. The oil is drawn from them pure, and in a liquid state, and is conveyed from thence in small jars. The whole annual produce of this district is estimated at more than 400,000 hogsheads. At Cole- brook Dale, in Shropshire, there is a considerable spring of petroleum, which was discovered at the depth of about thirty yards beneath the surface of the earth, in digging an archway for the conveying coals from a very deep pit. It was at first found to ooze from between the crannies of the rock, but it soon afterwards poured forth in a considerable stream. The utility of this ſluid being known, large iron pipes were formed for the conveyance of it into pits sunk for the purpose of receiving it. From these pits it is conveyed into immense caldrons, in which it is boiled until it attains the consistency of pitch. Since the first discovery of this substance, three different springs of it have broken out. One of these is near the celebrated iron bridge, and the fluid that issues from it is almost pellucid, but at the same time is thicker than treacle. Petroleum easily takes fire, and in burning yields a strong, sharp, and somewhat unpleasant odour; a thick and disagreeable smoke. In cold weather it congeals in the open air. In Pegu, and other parts of the East, petroleum is used in place of oil for lamps. Boiled with a species of resin, it is employed for painting the timber of houses, and covering the bottoms of boats and other vessels. In the latter respect it is considered to be particularly effica- 796. P. H. A. P. II A DICTIONARY OF MECHANICAL SCIENCE. cious, by protecting the timber from the attacks of marine. worms. It is also used by the inhabitants of Eastern countries. as a lotion in cutaneous eruptions, and as an embrocation in, bruises and rheumatic affections. The ancient Egyptians used. it in the embalming, of dead bodies. In some countries lumps of earth are soaked with petroleum, and are employed as fuel, Mineral Tar, or Barbadoes Tar, is a kind of fluid bitumen, sounewhat thicker than petroleum, and nearly of the consistence of common tar. It is viscid, of a black, brownish black, or reddish colour. In burning, its smell is disagreeable, but less pungent than most of the other kinds of bitumen. Its weight is somewhat greater than that of water. In the West Indies, where this substance is principally found, it is applied to many of the purposes for which the preceding species, is used; but its principal repute is considered to be as a sudoroſic in, disor- ders of the breast and lungs, though this application of it is considered to be very improper. It is likewise used as an external remedy in paralytic disorders. . PETROMYSON, the Lamprey, a genus of fishes belonging. to the class of amphibia mantes, of which there are eight species. The great lamprey is usually of a brown olive colour, tinged with yellowish-white. It is often three feet long, is an in- habitant of the seas, as its name indeed implies; but in the beginning of spring ascends rivers, in which it resides for a few months, then returning to the ocean. It is viviparous, . These fishes fasten themselves with the jagged edges of the mouth to large stones, with the most extraordinary firmness, and may be lifted with the tail to a considerable height, without being made to quit a stone of the weight of even ten or twelve pounds. . Their principle of vitality is extremely vigorous and jersevering, various parts of the body long continuing to move or some hours after it is divided ; and the head will adhere to :áröck for hours after the greater part of the body is cut away. In some large rivers of Europe these fishes are taken in vast numbers, and preserved with spices and salt as an article for merchandise. In this country the Severn is the most celebrated river for them, and they are much valued on their first arrival from the sea. They are considered a high luxury for the table, and the life of one of the kings of England will be recollected to have been terminated by his excessive partiality to potted lamprey. The lesser lamprey, is about twelve inches long, inhabits also the sea, but is found more frequently in the rivers than the former. It abounds in the Thames and Severn, and is preferred by many to the larger species, as being not so strong in taste. In some years half a million of these fishes have been sold from the neighbourhood of Mortlake, for the Dutch cod and turbot fishery, at the rate of two pounds per thousand. PETTY BAG, an office of Chancery, the three clerks of which record the return of all inquisitions out of every county, and make all patents of comptrollers, gaugers, customers, &c. PETUNSE, one of the substances of which porcelain is made, being a kind of coarse flint or pebble. PEUCEDANUM, or SULPHURwo RT, a genus of plants be- longing to the pentandria class, and in the natural method ranking under the 45th order, Umbellatae. - PEWTER. An alloy of lead and tin in the proportion of two parts of lead and one of tin, forms the solder which is used by plumbers; and, in the proportion of one part of lead to three parts of tin, it constitutes what is called ley pewter. The types which are used by printers for very large characters, are sometimes composed of an alloy of lead and copper. PHAETON, the Tropic Bird, in Natural. History, a genus of birds of the order anseres, of which there are three species. The common tropic bird is of the size of a widgeon, and the two middle feathers of the tail measure 13 feet at least. These birds are always found within, or at least, very near, the tropics. They frequently soar to a prodigious height, but generally are near the surface of the water, watching the movements of the flying fish, whose escape from the pursuit of the shark, porpoise, and other enemies beneath, is attended with destruction from the frigate or man-of-war bird, the pelican, and tropic bird, above. They occasionally repose upon the backs of the drowsy. tortoises, as the latter float upon the water, and in these cir- cumstances are taken with the greatest ease. They build in the every year, and the natives of the Sandwich Islands, where the tropic birds abound, pick them up in great abundance in various parts, and consider them as an elegantmaterial in their curious and elaborate dresses, particularly in their mourning, suits. | These birds are not admired, for food. - PHALANX, in Grecian antiquity, a square, battalion, con- sisting of 8000 men, with their shields joined, and pikes cross- i ing each other, so that it was next to impossible to break it, PHALENA, Moth, a genus of insects of the order lepidop- tera. This genus, like, that of papilio, containing a vast num- ber of species, is divided into assortments according to the dif- ferent habits of the animals. PHANTASMAGORIA, denotes a remarkable optical illu- sion, arising from a particular application of the magic lantern. In the exhibition of this spectacle, the audience are placed in a dark room, having a transparent screon between them and the lantern, which screen ought to be let down after the lights are withdrawn, and unknown to the spectators. The lantern being then properly adjusted on the opposite side, the figure intended to be exhibited is thrown upon the screen, which will, appear to the observers as if placed in free space, and by alter- ing the distance of the lantern, the figure may be made to appear of any size; which changes in its dimensions are attributed, by the observers, to the distance or proximity of the image, so that at one time it appears to be at an immense distance, and at another to be exceedingly near, and over the heads of some part of the audience. . The following is a descrip- tion of the exhibition of this spectacle, as shewn at the Lyceum theatre, London:—All the lights of the small theatre of ex- hibition were removed, except one hanging lamp, which could be drawn up so that its flame should be perfectly enveloped in a cylindrical chimney, or opaque shade. In this gloomy and wavering light the curtain was drawn up, and presented to the spectator a cave or place exhibiting skeletons, and other figures of terror, in relief, and painted on the sides or wall. After a short interval, the lamp was drawn up, and the audience were in total darkness, succeeded by thunder and lightning; which last appearance was formed by the magic lantern, upon a thin cloth or screen, let down; after the disappearance of the light, and consequently unknown to most of the spectators. These appearances were followed by figures of departed men, ghosts, skeletons, transmutations, &c. produced on the sereen by the magic lantern on the other side, and moving their eyes, mouth, &c. by the well-known contrivance of two or more sliders. The transformations are effected by moving the adjust- ing tube of the lantern out of its focus, and changing the slider during the moment of confused appearance. It must be again remarked, that these figures appear without any surrounding circle of illumination, and that the spectators, having no pre- vious view or knowledge of the screen, nor any visible object of comparison, are each left to imagine the distance according to their respective fancy. After a very short time of exhibiting the first figure, it was seen to contract gradually, in all its dimensions, until it became extremely small, and then Vanished, This eſfect, as may easily be imagined, is produced by bringing the lantern nearer and nearer the screen, taking care at the same time to preserve the distinctness, and at last closing the aperture altogether, and the process being (except as to bright- ness) exactly the same as happens when visible objects become more remote, the mind is irresistibly led to consider the figures as if they had receded to an immense distance. Several figures of celebrated men were thus exhibited with more transforma- tions; such as the head of Dr. Franklin being converted into a skull, and these were succeeded by phantoms, skeletons; and various terrific figures, which, instead of seeming to recede and then vanish, were (by enlargement) made suddenly to advance, to the surprise and astonishment of the audience, and then disappear by seeming to sink into the ground. PHARMACY, the art of preparing, compounding, and pre- serving medicinals. The preservation of medicines merely consists in the application of rules for collecting vegetable, animal, and mineral productions, at certain seasons or under particular circumstances, and of ensuring them against the injuries they would suffer by exposure to light, heat, air, mois- ture, &c. this, therefore, is the least extensive, and peculiar woods, and will perch on trees. They shed their long feathers | department of the pharmaceutic art. It is the preparation and P H. A P H A 797 DICTIONARY OF MECHANICAL SCIENCE. composition of medicinals that constitute the principal objects of the science of pharmacy. - PHARO, is the name of a game of chance, the principal rules of which are: the banker holds a pack consisting of 52 cards; he draws all the cards one aſter the other, and lays them down alternately at his right and left hand, then the ponte may at his pleasure set one or more stakes upon one or more cards, either before the banker has begun to draw the cards, or after he has drawn any number of couples. The banker wins the stake of the ponte when the card of the ponte comes out in an odd place on his right hand, but loses as much to the ponte when it comes out in an even place on his left hand. The banker wins half the ponte's stake when it happens to be twice in one couple. When the card of the ponte being but once in the stock, happens to be the last, the ponte neither wins nor loses; and the card of the ponte being but twice in the stock, and the last couple containing his card twice, he then loses his whole stake. PHAROS, A LIGHT. House. (See the Plate.) The Pharos of Alexandria, built on a stnall island at the mouth of the Nile, was in ancient times so famous as to impart its name to all the rest. It was erected by the much celebrated Sostrates, with such great magnificence, that it is said to have cos". Ptolemy Philadelphus eight hundred talents. It had several stories raised one over another, adorned with columns balustrades, and galleries, of the finest marble and workman- ship. At present nothing is to be seen of the small island where it stood, but an irregular castle, without ditches or out- works of any strength. Out of this clumsy building rises a tower, which serves for a light-house, but the grandeur of the old one has totally disappeared. The famous Colossus' of Rhodes served also as a pharos. country, are far more interesting, we purpose giving, under the present word, an account of the erection of the Bell Rock light-house. England, which is never behind in deeds of mercy, very early attempted, by the erection of the Eddystone light-house, to ward off the dangers of the sunken reef of rocks on which so many vessels have been shipwrecked, and which rendered the navigation of the channel so very hazardous : and Scotland, whether we consider the dangers to be prevented, or the diffi- culties to be overcome in the execution, can now boast in the Bell Rock light-house, a national work, equal in every point of view to any in the world. If, therefore, England has adorned the name of Smcaton with honours, which it is to be hoped will prove immortal, Scotland ought equally to glory in that of Stevenson. - The reef of rocks on which the Bell Rock light-house is founded, is about 427 feet Jong and 230 feet broad; at the ordinary height of spring tides it is about 12 feet under water; and from the floating sea-weed, the ridge can be traced 1000 feet farther in a south-westerly direction, when the tides are very low. It is situated on the eastern coast of Scotland, about 16 miles S. by E. from the Red-head; 12 miles S.E. from Arbroath ; 17 miles N. by E. from the Isle of May; and 38 miles N. by W. from St. Abb's-head. Its geographical posi- tion is in 56°29′ of north latitude, and 29 22 of west longitude. The reef presents an exceedingly rugged and uneven surface. The rock is composed of red sand-stone similar to the strata of the contiguous promontory of Red-head, and of the opposite shores of Dunglas in Berwickshire. The present vegetation of the rock consists only of sea plants; some of them not of com- mon occurrence on our coast. It is the occasional resting- place of the seal and the cormorant; and is the chosen resi- dence of numerous marine vermes. At the distance of 100 yards, when the tide is low, the water varies from two to three fathoms in depth. The greatest depth between the rock and the opposite shores of Fife is 23 fathoms. This rock, though a mere spot on the surface of the ocean, produces all the re- markable phenomena of in-shore and off-shore tides, which exist on the projecting coasts of the mainland, or among the Scotish islands. . . . . In the erection of the Eddystone light-house, the dangers and difficulties which were encountered and overcome, owing to the smallness of the surface of the rock, were great and . 82. IBut as those which have been erected in more modern days, on the shores of our own numerous; and although the surface of the Bell Rock was con- siderably larger, still, being more sunk, and only discovered at low water, the dangers to be encountered were equally great and overwhelming. Owing to the enlarged diameter of the rock, Mr. Stevenson, the engineer, was enabled to make the masonry of this building more than double the cubical con- tents of the Eddystone.—The following short table will exhibit to our readers the relative dimensions, &c. of the two light- houses:– - - Eddystone. Bell Rock. Level with low Level with high water mark. Height of the rock, about } water mark Height of masonry above & the rock . . . . . . . . . . . . $ 70 feet. 100 feet. Diameter of the first en- tire course........... } 26 feet. 42 feet. Cubic contents in feet, 7 - * 13, 147. 28,530 about . . . . . . . . . . . . . . . . § y yºsºvº • Expense understood to Ascertained have been about. . . . . . } £21,000. £61,331. 9s. 3a. Very early, no doubt, attempts were made to obviate the dangers of this fatal spot; and accordingly, tradition reports, that the monks of the Abbey of Arbroath erected a bell on the rock, which was to be rung by machinery affected by the flow- ing and ebbing of the tides, whence the present name of the rock, it is said, took its rise. - - About the year 1800, the board of commissioners of the northern light-houses, a body organized in 1788, and to whose labours, which are purely ea officio, and without any renumera- tion whatever, the country is under the greatest obligations, being desirous of erecting a light-house on the Bell Rock, re- quested Mr. Stevenson, their engineer, to survey the spot. He did so, and reported that he conceived it quite practicable to erect one on the plan of the Eddystone light-house. His first landing on the rock was in the summer of 1800, when the boat's crew picked up a variety of articles of shipwreck, comprising a soldier's bayonet, a cannon ball, a hinge and lock of a door, a ship's marking iron, and part of a compass, several pieces of money, a shoe-buckle, &c. - In the year 1803, a bill for the erection was brought into parliament, but was lost in consequence of its being considered that it embraced too wide a range of coast for the collection of the duty. In the year 1806, another bill was introduced into parliament, and passed into a law. This act provided for a loan to the board of £25,000; and as there were surplus duties to the amount of £20,000 in the hands of the commissioners, the work commenced in 1807, with funds to the amount of . £45,000. From the insulated and distant situation of this rock, the first object of the engineer was to provide a convenient resi- dence for the artificers, while engaged at the work. This was done by mooring a tender off the rocks, and on it a temporary light was exhibited. A vessel was provided for conveying the workmen between the shore and the rock. The outer casing of the building was to be of Aberdeen granite, and the internal part of sand-stone. Quarries were opened near Aberdeen for supplying the one, and at Ringoodie, near Dundee, for supply- ing the other. The principal establishment on the shore was at Arbroath, where a large yard was enclosed for the purpose of preparing the stones. Barracks were likewise erected for | the residence of the workmen when on shore. It was on the 7th of August 1807, that Mr. Stevenson ac- companied by Mr. Peter Logan, his principal assistant, and a few workmen, went off to the Bell Rock, and fixed on the site of the building. They immediately commenced their opera- tions, by cutting away a thick coating of large sea weed, and tracing the line of the foundation with pick-axes on the rock. At this time it was agreed on, that those workmen who went out to the rock should remain for a month without going ashore. They, on the other hand, fixed their terms at 20s. per week, “summer and winter, wet and dry, with free quarters and vic- tuals when at the rock.” Premiums, and the allowance they were to receive for working on Sundays, “they left to the honour of their employers.” . At the commencement of this arduous undertaking, two or three *about on the rock was considered a very good 9 798 P. H. A. P H. A. DICTIONARY OF MECHANICAL SCIENCE. tide’s work: and the men were then obliged to collect their tools and implements, betake themselves to the boats, and, often under great disadvantages and, with considerable risk and danger, seek refuge in the tender which was moored off the rock. To provide a temporary refuge for the workmen on the rock, in case of any accident happening to the boats, formed part of Mr. Stevenson's original design, and he accordingly lost no time in setting about the construction of a wooden bea- con or shelter-house, which we have represented in figure A. This most necessary place of refuge was triumphantly com- pleted in the latter end of September, and, as Mr. Stevenson says, “robbed the rock of much of its terrors, and gave a facility to the wérks which could not otherwise have been easily obtained.” The erection of this temporary shelter-house forms an exceedingly interesting part of the history of this altogether interesting undertaking. Six beams, about 50 feet in length, were fixed upright on the rock, inclosing a space, the diameter of which was 35 feet, while they met in a point at the top. They were fixed at their base by great iron staunch- ions, weighing about 140 lb. each, which were sunk into the rock about 20 inches, and were wedged with successive slips of fir, oak, and iron : at the top the beams were bolted together, and strongly fastened by hoops of iron, see fig. (first) G. The works at this stage depended entirely, it may well be sup- posed, on the state of the weather: they were obliged there- fore to work on Sundays, and by torch-light at night, when the tide permitted. The work was thus carried on under circum- stances of peculiar hazard, and several very narrow escapes were made. The sloop Smeaton, which was used as a tender, at one time broke adrift from her moorings, carrying with her one of the artificers’ boats, and from the current of the tides it was utterly impossible she could return until after the rock would be overwhelmed by the sea. At this time there were 32 men on the rock, and the two boats which were left would hold little more than half that number, especially in such a heavy sea. This accident of the breaking loose of the tender, and carrying away of the boat, was only known to Mr. Stevenson and the . Janding-master: the workmen, sitting or kneeling at their work in the foundation pit, were in perfect ignorance of their peril- ous situation, till the rise of the sea drove them from the works, and made them seek their respective boats for their jackets and stockings. Their dismay and consternation on beholding two boats only instead of three, must have been great; yet “not a word,” says Mr. Stevenson, “ was uttered by any one, but all appeared to be silently calculating the numbers, and looking to each other with evident marks of per. plexity depicted on their countenances.” A pilot-boat, how- ever, bringing letters from Arbroath to Mr. Stevenson, for- tunately arrived at this dreadful juncture, and thus being all relieved from the rock, they set sail in Search of the tender, which they reached, and got safely on board of, though after a most dreadful passage, in which Mr. Stevenson’s face and ears were encrusted with a film of salt from the sea-spray breaking over the bows of the boat. In the progress of the works in the summer of 1808, a con- siderable addition was necessary to the shipping establishment. Besides the floating light-ship which had been moored off the rock, a schooner of 80 tons was provided as the principal ten- der. Stone-lighters of 40 tons were also provided for the con- veyance of materials; and three praam boats, each capable of carrying about 10 tons upon deck. These last were employed for removing the stones from the lighters anchored off the rock to the wharfs and cranes on the rock. They were doubly forti- fied by a water-tight ceiling, or lining, in case of damage by being grounded upon the rock, and were farther prepared for the worst by a number of empty casks, which were stowed under deck, and were of themselves capable of keeping the praams afloat. There were also several attending boats for transporting the artificers from the tender to the rock, and one of them was fitted up as a life-boat upon Gratehead's principle. The moorings of the various craft consisted of chains, with cast-iron mushroom anchors, admirably adapted to the situ- ation. Tracks of iron railways were laid upon one level, along the rough and uneven surface of the rock, on which the great blocks of stone were wheeled upon waggons also constructed chiefly of cast-iron. The little wharfs were provided with cranes adapted to the peculiarities of the respective situations. A descriptive account is given by Mr. Stevenson, in his work, of the various cranes, sling-carts, stone-jack, winch-machine, and Lewis-bat for quarrying purposes, of the moulds for stone- cutters, pumps, and other machinery, in a detailed manner, extremely interesting to the engineer and the architect. At first, the whole time of flood-tide was a period of leisure. During such periods, the amusements to which the men resorted were as various as their inclinations. Some, fond of reading, were busily engaged at their books; some, who were more musically inclined, played the violin or the flute; and others amused themselves by fishing. The great evil, however, of which they all complained, and which time itself hardly cured, was sea-sickness. Every nerve was therefore strained to erect barracks for their accommodation upon the beams on the rock, which was at once to relieve them from the constant liability to sickness, and from the danger and perplexity of the movements, both by night and day, in boats to and from the rock. * By strenuous and unremitting exertions, the shelter-house was erected, and the foundation-pit of the building prepared, by the middle of the month of July, in this the second season of the work. The foundation had the appearance of a great circular platform, of compact red sand-stone, measuring 42 feet in diameter, surrounded by an irregular margin of rock, rising from 18 inches to 5 feet. In the work-yard at Arbroath, where the materials were prepared, each stone for the first and second courses of the light-house was accurately marked, so that its relative position in the building on the rock could at once be recognized. The stones were cut of a dove-tail form, on a plan similar to those of the Eddystone light-house. This is very well represented in fig. (first) A, which exhibits one half of the second course of masonry. . - The foundation stone at the Bell Rock was laid, by Mr. Stevenson, with masonic ceremony, on the 10th of July, 1808. About eighty persons were present, and if the situation had been eligible, no doubt some thousands would have attended. After this period the work went on with much alacrity, from ten to twenty blocks of stone being generally laid in the course of a tide. Owing to the use of cranes instead of the mere ordinary apparatus, much precision and facility were given to the operations of the builders, and by the latter end of Sep- tember the works were brought to a conclusion for the season. The building raised to a level with the highest part of the mar- gin of the foundation-pit, or about five or six inches above the lower bed of the foundation-stone, was computed at 388 tons of stone; consisting of 400 blocks connected with 738 oaken trenails, and 1215 wooden wedges. The number of hours of low-water work upon the rock, this season, was 265, of which number only 80 were employed in building. It was, farther, highly satisfactory to find that the apparatus, both in the work- yard at Arbroath and also the craft and building apparatus at the rock, were found to answer every purpose much beyond expectation. The operations of this season, therefore, afforded the most flattering prospects of the practicability of complet- ing the solid part of the building, or 30 feet of the light-house, in the course of another year. The builders returned to their barracks, and work-yard at Arbroath, for the winter; and, on the tender's entering that harbour, the artificers were greeted with cheers from their friends and comrades on shore, who thronged upon the quays to welcome their return. This sea- son's success, however, was chequered with a cross accident, in the loss of a sailor from one of the stone-lighters. In the spring of 1809 the operations recommenced ; and the building, during the course of this season, advanced with great rapidity. The winter storms had done no injury; the whole of the courses which had been laid, and the shelter-house itself, was, in the third year from its erection, remaining quite secure. The artificers, from this tried stability of the shelter-house, were rendered more confident, and more impatient of the trouble and inconvenience attending landing and re-landing on the rock from the tender: and, therefore, before it was quite fitted up for a barracks, they took possession of it through the day. One evening, however, a gale of wind preventing the boats from taking them off, Mr. Peter Logan, and Mr. Francis F H A P H A 799 I) ICTIONARY OF MECHANICAL SCIENCE. Watt, two of the overseers at the rock, with eleven of the arti- ficers, were necessarily left there for 30 hours, while very often the waves washed over their yet imperfectly formed abode : the mortar gallery below them was carried away by the vio- lence of the storm, and one of the cranes was broken to pieces. Hitherto the operations of the builders were wholly confined to the lower-water work. From the great exertions, however, made by the shipping department in supplying materials this season, the builders were enabled to lay 30 blocks of stone in the course of a tide. . When the building had attained the height of the ninth course, the guy ropes of the usual description of beam crane, became too upright, and it was found necessary to resort to other measures. A new machine, called a Balance Crane, was therefore put in preparation for the use of the works next sea- son. In this, the upright shaft was to be retained in an erect position, by a weight acting on the opposite end of the loaded beam, which was thus to be kept in equilibrio. The light-house now began to appear considerably above the rock at low-water ; and the tide’s work, in moderate weather, extending to five or six hours, or an hour or two after the rock was under water. The shelter-house was now fully occupied as a barrack, smithy, and mortar gallery; and between this fabric and the rising walls of the light-house, a rope ladder of communication was distended. - - . Upon Sunday, the 20th of August, this year, the entire twenty-second course of the building, consisting of 51 blocks, was laid; after which, for the first time, prayers were read in the shelter-house, the whole workmen being assembled in one apartment, and two of them joining hands to form a desk to support the Bible during the service. On the 25th of this month, the building” operations were brought to a conclusion for the season. . At the commencement of the works in Spring, 1810, a great stock of prepared materials was in readiness at Arbroath, excellent sand-stone having been procured from Milnefield Quarry, on the Frith of Tay. The stones for the cornice and light-house, from Craigleith, near Edinburgh, were likewise prepared, and in readiness for shipping at Leith. A large gangway or bridge of timber had been prepared during the winter, to render the communication between the shelter-house and light-house more perfect, than by means of the rope lad- der; and which was calculated to be of great use for raising the materials upon the building. * The first circumstance attended to, in commencing the ope- rations of this season, was to fix upon the proper situation for the door of the light-house ; and the heaviest seas being deter- mined to be from the north-east, the door was laid off towards the south-west. The first cargo of stones was brought to the rock about the middle of May; and from the very complete and systematic arrangement of the works, the building ope- rations were brought to a close during the month of August, without any material obstacle having been experienced. This increased facility in building was ascribed partly to the expe- rience acquired by practice during former seasons, and partly to the admirable adaptation of the balance crane, formerly mentioned, for laying the stones on their places upon the building. The works were, however, occasionally interrupted, by the shipping being dispersed in gales of wind, when they were sometimes driven upwards of forty miles from their sta- tion. At such times, the artificers were closely cooped up in their barrack upon the rock, in a state of painful inactivity, and often with prospects very forlorn. It is certainly not a little remarkable, that in the course of their extensive opera- tions, not a single stone was lost, or even so damaged as to be rendered unfit for the building, notwithstanding the numerous changes and shiftings from hand to hand, which each stone underwent before it was finally laid with mortar. In some instances, indeed, blocks of stone were lifted from their beds by the run of the sea; but none were carried entirely away. In the engravings, we have given an elevation, plan, section, and details of the light-house. The lower courses of stones were trenailed and wedged together with oak timber to the height of upwards of forty feet, or throughout the solid part of the building. At the stone staircase, leading from the door to the first floor, the walls are of the medium thickness of about seven feet; this thickness gradually diminishes upwards, till, under the cornice of the building, it extends only to 18 inches. The stones of the walls of the several apartments are connected at the ends with dove-tail joints, instead of square joggles, as in the solid, and in the staircase. The floors are constructed in a manner which adds much to the bond or union of the fabric. Instead of being arched, which would have given a tendency or pressure outwards, on the walls, the floors are formed of long stones, radiating from the centre of the respec- tive apartments, and at the same time, forming a course of the outward wall of the building ; these floor stones are also joggled sidewise, and, upon the whole, form a complete girth at each story. This is very well seen in figures K and H. In this manner, the pressure of the floors upon the walls is rendered perpendicular, while the side joggles resemble the grove and feather in carpentry, exemplified in figs. D, E, and F. In the stranger’s room, or library, the roof takes an arched form, but the curve is cut only upon the interior ends of the stones of the cornice, the several courses of which it is com- posed being all laid upon level beds. This is seen in fig. 2. Towards the latter end of August, the masonry was com- pleted, and the operations of erecting the light-room com- menced. The shelter-house, which had hitherto been crowded by more than 30 persons, during the summer, was now more thinly peopled. Towards the end of the month of October, the balance crane, and the bridge of communication were dis- mantled; the former was no longer necessary, and in place of the latter the rope ladder was again distended; the shelter- house being still occupied as the place of accommodation for the artificers employed in fitting up the light-roof and reflect- ing apparatus: seen in figs. 2, and K. In the month of Decem- ber the keepers took possession of the light-house : about the middle of that month, the whole apparatus and stores, having been safely landed and lodged in the house, the light was advertised for exhibition on the 1st of February, 1811. On the afternoon of that day, it was accordingly exhibited; and the floating light was extinguished, as being no longer necessary. Since the completion of the light-house, the shelter-house has been removed, and also part of the iron railways, leaving only such tracks of them upon the rock, as were thought necessary for landing the stores, and communicating with the light-house. Instead of a rope ladder, the communication between the rock and the entrance door, a height of about 30 feet was also formed by a brazen stair, which answered also for part of a thunder rod, and facilitated the raising of the stair, by a peculiar sort of crane adapted to the purpose. The for- tunate position of the entrance door rendering it seldom neces- sary to shut it in summer, an inner door of brass has been hung, which is found to be a great conveniency to the inmates. Dur- ing storms, when their double doors, double windows, and storm shutters, are closed, the light-keepers mention that they occasionally feel a tremor in the building, from the shocks of the sea, but that all is quiet within, and they hear nothing of the dashing and roaring noise of the sea. • We shall now proceed to describe the details of the work as represented in the various engravings on the plate:— Fig. (second) A, the shelter-house used as a barrack, con- sisted of several stories, viz. Fig. (second) B, is the lower floor, or a gallery in which the smiths and mortar-makers latterly worked, with the position of the bellows, anvil, hearth, lime tubs, and mortar casks. Fig. (second) C, represents the second floor of the cooking- room, the caboose or hearth, chimney, provision casks, and the life-boat suspended by davits from the principal beams of the shelter-house. Fig. (first) D, is the ground plan of the fourth floor, in which the workmen resided ; the five parallelograms shew the posi- tion of the beds, which were also ranged in five heights, except- ing at the man-hole or place of entrance, where were only three. Fig. (first) E, is the third floor, or foreman and engineer’s cabins. Here also thcir assistants resided. Fig. (first) F, represents one of the principal beams cut across at the clasp-plate, and the great iron stanchions and spear bolts that bound the whole together. . Fig. (first) G, represents, part of one of the beams of the shelter-house connected with the great stanchions, with its 800 P H I P H. A DICTIONARY OF MECHANICAL scIENCE. bolts, which were fitted on each side of the beam; the clasp- plates and spear bolts that bound the whole, and fixed it to-the rock, are plainly marked. Fig. (first) H, is, an enlarged view of two of the bracing chains, with their tightening shackle meeting in a strong ring attached to the massive iron batts sunk into the rock about 20 inches, and wedged with timber. * Fig. 1, is an outside view of the Bell Rock Light-house. Fig. 2, is an entire section of the Pharos or Light-house, exhibiting its various stories and apartments, as represented in the following diagrams. The literals A, B, C, D, E, F, G, H, K, are enlarged views of the several parts of the Pharos just now described. Fig. (first) A, representing the first entire course of the masonry, measures 42 feet, in diameter. The dove-tailed method of connecting the solid part of , the Pharos here delineated extends to the height of the entrance door. Fig. (first) B, the twenty-seventh course and first of the staircase, measures 6 feet 4 inches in diameter, within the walls, and 19 feet 8 inches over the walls. This course is ele- wated 32 feet 8 inches above the rock at the foundation of th first stone. . - Fig. (first) C, the thirty-ninth course of the building and first of the provision store-room, is 45 feet 11 inches above the foundation; 11 feet 9 inches diameter within walls; 18 feet over walls; and from the floor to the roof, the height is 8 feet 7 inches. Fig. (second) D, is a plan of the floor of the light, or oil room store, being the forty-eighth course, which is 55 feet 10 inches above the foundation. This apartment, within walls, measures 11 feet 10 inches; over walls, 16 feet 10 inches; and its height is 8 feet 7 inches. - Fig. (second) E, being the kitchen floor, forms the fifty-seventh course, which is elevated 65 feet 8 inches above the foundation. This room is 11 feet 11 inches in diameter within, over all 16 feet; and its ceiling is .8 feet 9 inches high. 4. Fig. (second) F, is the bed room floor, or the sixty-sixth course of the building, and is elevated 75 feet 8 inches above the foundation. It measures 11 feet 113 inches diameter, and over all 153 feet. The walls are 9 feet in height. Fig. (second) G, the next in order, is the floor of the library or stranger's room, 85 feet 11 inches above the foundation. Its diameter within 12 feet, over walls 15 feet, and the height of the roof at the centre, is 11 feet 1 inch. Fig. (second) H, the light room and balcony floor, or 86th course of the building, which is elevated 97 feet 9 inches above the foundation, measures 11 feet in diameter within, and 13 feet 6 inches over walls. The stones of the floor of this apartment, as will be observed in the engraving, extend from the centre stone to the circumference of the balcony, varying from 7 feet to 7 feet 6inches in length. The parapet wall of the light room has its outward face octagonal, but is worked circular within. The light room measures from the floor to the top of the stone work, or sole of the glazed sash frames, 6 feet. Fig. K, is a plan of the lantern, shewing the position of the trimming path, and reflector frame. The height of the pharos from the foundation to the sill of the sash frame, is 102 feet 6 inches, and from thence to the lining of the cupola, 13 feet 4 inches. * The net cost of the Bell Rock Light House, and tilterior works connected with that establishment, was £61,331. 9s. 2d. There Were 2,083,445 tons of granite and sandstone used in the con- struction; 13 cubic feet of granite, and 14 cubic feet of sand- stone, were allowed to the ton; 204 barrels of sand; 377 bar- rels of lime ; 255 barrels of pozzolano; 6585 wédges of oak, in pairs; 4065 oak trenails; 450 sandstone joggles; 21,598 cubic feet of sandstone, and 6932 cubic feet of granite. PHASEOLUS, Kidney Bean, a genus of the diadelphia de- candria class of plants, the corolla whereof is papilionaceus, the vexillum is cordated, obtuse, emarginated, and reclined with reflex sides; the alae are roundish, of the same length with the vexillum, and stand upon long ungues; the carina is narrow, and revolves spirally in a contrary direction to the sun ; the fruit is a long, straight, coriaceous, and obtuse pod; the seeds are oblong, compressed, and kidney-shaped. There are 21 species, - - PHASES, in Astronomy, denote the various appearances of the moon at different ages, being at one time a crescent, then a semicircle, then gibbous, and lastly full; after which, the same phases return again in the same order. 'Venus and Mercury have the same phases as the moon, and Mars par- takes of them, in some measure, being at times gibbous ; the same must also have place in a less degree with the other supe- rior planets. The same term is also applied to denote the appearance of the moon or sun when eclipsed. -- PHASIANUS, the Pheasant, in Natural History, a genus of birds of the order Gallinae. Generic character: bill short, strong, and convex; head covered in some degree with carun- culated flesh; legs generally with spurs. There are ten species. P. gallus, or the wild pheasant, inhabits the forests of India, and has been seen, indeed, by navigators in almost all the Indian and South Sea islands. This is the undoubted origin of all the domestic varieties throughout Europe, of which we shall notice the following:—P. gallus, or the dunghill cock. The most interesting animal under this variety is the game cock, which is found in greater perfection of vigour and courage in England than in any other country; and the irascibility and jealousy of which has, in almost all ages, occasioned it to be employed in the sanguinary diversion of cockfighting. PHENOMENON, is strictly an appearance, but more com- monly confined to those only of an extraordinary nature, parti- cularly as relating to the heavens, or heavenly bodies; as comets, meteors, shooting stars, &c. We also speak of the phenomenon of the magnet, of electricity, &c. - PHILOLOGY, a science, or rather assemblage of several sciences, consisting of grammar, rhetoric, poetry, antiquities, history, and criticism. - - PHILOSOPHER, a person well versed in philosophy, or one who makes profession of, or applies himself to the study of, those sciences. PHILOSOPHY, the knowledge or study of nature or mora- lity, founded on reason and experience, the word originally implying a love of wisdom. The only part of philosophy, how- ever, which belongs to a work of this kind, is that which is called natural or experimental philosophy, and which may be generally defined that branch of science which derives its data from experiments and observations, on which the whole system is supported, as is that of geometry upon axioms and definitions. Natural Philosophy, is the science that unfolds those gene- ral principles which connect the events of the material world. It assumes as a basis, the constancy and permanence of the actual state of things. The appearances which present them. selves to our observations, are called phaenomena; and the com- mon relations which pervade these phaenomena, are termed laws. The business of the natural philosopher is to ascend patiently from effects to causes, till he approaches the fountain of all power and intelligence; and from that eminence again to descend, and trace the lengthened chain of consequences. This double mode of procedure corresponds to the analysis and synthesis of the ancient Greek geometry. The analysis, or investigation of physical facts, is conducted, either by observa- tion, or by experiment. Observation is the close inspection, and attentive examination, of those phenomena which arise in the course of nature. Experiment, as the term implies, consists in a sort of trial or artificial selection and combination of circum- stances, for the purpose of searching after remote results. The main object of the philosopher is always to separate the various effects which are blended together in the ordinary concurrence of events. The primary facts being once detected from close observation, or delicate experiment, the synthetical deduction can be safely pursued by the exercise of a sober and cautious logic. But the most important instrument, in forwarding this process of combination, is geometry, to which indeed we are indebted for whatever is most valuable in physical science. The most satisfactory mode of proceeding in the exposition of the phenomena, is to consider bodies as (1) in a state of rest, and (2) in a state of motion. The essential properties which belong to each distinct body, form a branch of science that may be termed Somatology, but which has hitherto been styled incor- rectly Corpuscular Philosophy. A course of natural philosophy may be properly distributed under twelve distinct heads:— P H O R H O 801 DICTIONARY OF MECHANICAL SCIENCE. 1. Somatology, which includes the exposition of the general properties of bodies, essential to their separate existence. 2. Statics, which explains the equilibrium of bodies, result- ing from their mutual action, or from combined pressure and divellence. . . . 3. Phoronomics, or Dynamics, which explores the laws of motion, and traces the flux of changes produced by the appli- cation of force. . - - - 4. Physical Astronomy, which is the extension of dynamics, to develop the great phenomena of the heavens. It explains the figures and motions of the planets, and deduces their various effects. 5. Mechanics, in which the principles of dynamics descend to improve the vulgar arts, and to explain the composition and arrangement of the various machines contrived to assist the labour of man. 6. Hydrostatics, which consists in the application of the prin- ciples of statics to explain the equilibrium of liquids or of fluids in general. It treats also of the construction of works depending on such properties. & 7. Hydrodynamics, or Hydraulics, which consists in applying dynamics to the motion of liquids. It consequently investi- gates the construction and performance of the various engines employed to raise water, or which are driven by the impulsion of that fluid. - 8. Pneumatics, includes the application of statics and dyna- mics to air and other gaseous fluids. It explains the constitu- tion, the operations, and general phenomena, of our atmosphere. 9. Photonomics, which treats of the properties and operations of light. ſº Pyronomics, which explores the properties and operations of heat. 11. Magnetism, which investigates the properties of the load- stone, and their application to the suspended needle. 12. Electricity, which explains all the brilliant phenomena derived from those first produced by the rubbing of amber. Such appears to be the systematic arrangement of those sub- divisions; but it will admit of being conveniently modified, according to the taste or judgment of philosophers. PHLEGM, or WATER, in the animal economy, is considered an elementary body, the characters of which are fluidity, insi- pidity, and volatility. PHLEUM NoDosu M. (Bulbous Cat's-Tail-Grass.) This grows very frequently in dry thin soils, where it maintains itself against the parching sun by its bulbous roots, which lie dormant for a considerable time, but grow again very readily when the wet weather sets in, a curious circumstance, which gives us an ample proof of the wise contrivance of the great Author of nature, to fertilize all kinds of soil for the benefit of his creatures here below. There is another instance of this in the Poa bulbosa, Bulbous meadow-grass, which grows on the Steine at Brighton, and which, after being kept in papers two years out of ground, has vegetated afterwards. PHLOAS, a genus of vermes testacea. The inhabitants of this genus perforate clay, spongy stones and wood, while in the younger state, and they increase in size, enlarge their habitation within, and thus become imprisoned. They contain a phospho- rus liquor, of great brilliancy in the dark, and which illuminates whateyer it touches. There are 12 species. PHOCA, the Seal, in Natural History, a genus of mammalia of the order ferae. There are nineteen species, of which we shall notice the following :-The common seal, or sea-calf, found on the sea coasts of cold regions, both to the north and south, often in extreme abundance, and generally about five feet in length, closely covered with short hair. They swim with great vigour and rapidity, and subsist on various kinds of fish, which they are often observed to pursue within a short distance from the shore. They possess no inconsiderable sagacity, and may without much difficulty, if taken young, be familiarized to their keepers, and instructed in various gesticulations. They are supposed to attain great longevity. The female is particularly attentive to her young, and scarcely ever produces more than two at a birth, which, after being suckled a fortnight on the shore, where they are always born, are conducted to the water, and taught by their dam the means of defence and subsistence; and when they are fatigued by their excursions, are relieved 82, - and even weeks. by being taken on her back. They distinguish her voice, and attend at her call. The flesh of seals is sometimes eaten, but they are almost always destroyed for their oil and skins. The latter are manufactured into very valuable leather, and the former are serviceable in a vast variety of manufactures. The ursine seal grows to the length of eight feet, and to the weight of a hundred pounds. These are found in vast abundance in the islands between America and Kamtschatka, from June till September, when they return to the Asiatic or American shores. They are extremely strong, surviving wounds and lacerations which almost instantly destroy life in other animals, for days, They may be observed not merely by hun- dreds, but by thousands, on the shore; each male surrounded by his females, from eight to fifty, and his offspring amounting frequently to more than that number. Each family is preserved separate from every other. The ursine seals are extremely fat and indolent, and remain with little exercise, or even motion, for months together upon the shore. This harmless seal has been frequently mistaken for the fabled mermaid. PHOENICOPTEROS, the Flamingo, in Natural History, a genus of birds of the order grallae. The common flamingo, the only species noticed by Latham, is nearly of the size of a goose, and upwards of four feet long. When mature in plumage, these birds are all over of the most deep and beautiful scarlet : but this muturity they never acquire till their third year. They are found in France, Spain, and Italy, in Syria, and in Persia, but more frequently than any where else, on the coast of Africa, downwards to the Cape. They build their nest of mud, in the shape of a hillock, and in a cavity on the top of it the female deposits two white, eggs, on which she sits, having her legs stretched out, one each side of the hillock. PHOENIX, the great palm or date tree, a genus of plants of the order palmae. There is only one species, viz. the dacty- lifera, or common date tree, a native of Africa and the eastern countries, where it grows to 50, 60, and 100 feet high. , PHOENIX, in Astronomy. Our astronomers have probably given this constellation the name of Phoenix, after the exam- ple of the Arabians, who were acquainted with it under the appellation of the Griffin, or Eagle, from the most remote anti- quity. These people adored an idol under the form of an eagle, and according to Hyde, (Hist. Vet. Pers.) this eagle was one of the celestial signs. The brilliant star called Achermar, beside this asterism, is distinctly visible during the summer months in Arabia, whence the Phoenix was fabled to come. Erasmus says the Pheenix was the symbol of the year, or of the annual revolution; and to the Egyptians this constellation rose, as it were, from Arabia, shortly before the commencement of their sacred year. - PHONICS, the same as Acoustics. PHOSPHATS, salts formed by the phosphoric acid, with the alkalies, earths, and metallic oxides. The phosphats at present known amount to twelve; two of which are triple salts. PHOSPHITES, salts formed with the phosphorous acid united to the earths, alkalies, and metallic oxides. PHOSPHORIC ACID. The base of this acid, or the acid itself, abounds in the mineral, vegetable, and animal kingdoms. In the mineral kingdom it is found in combination with lead, in the green lead ore ; with iron, in the bog ores which afford cold-short iron ; and more especially with calcareous earth in several kinds of stone. Whole mountains in the province of Estremadura, in Spain, are composed of this combination of phosphoric acid and lime. In the animal kingdom it is found in almost every part of the bodies of animals which are not considerably volatile. There is not, in all probability, any part of these organized beings which is free from it. It has been obtained from blood, flesh, both of land and water animals; from cheese; and it exists in large quantities in bones, com- bined in calcareous earth. Urine contains it not only in a dis- engaged state, but also combined with ammonia. PHOSPHOROUS ACID is prepared by exposing phospho- rus during some weeks to the ordinary temperature of the atmosphere. Even in winter the phosphorus undergoes a slow combustion, and is gradually changed into a liquid acid. For this purpose it is usual to put small pieces of pbosphorus on the inclined side of a glass funnel, through which the liquor which is formed drops into the bottle placed to receive it. From 9 S 802 P H O P H Y DICTIONARY OF MECHANICAL SCIENCE, an ounce of phosphorus about three ounces of acid liquid may be thus prepared. - PHOSPHORUS, a substance which shines by its own light. The discovery of this singular substance was accidentally made in 1677, by an alchemist of Hamburgh, named Brandt, when he was engaged in searching for the philosopher's stone. Kunkel, another chemist, who had seen the new product, associated himself with one of his friends, named Krafft, to purchase the secret of its preparation; but the latter deceiving his friend, made the purchase for himself, and refused to communicate it. Kunkel, who at this time knew nothing further of its prepara- tion, than that it was obtained by certain processes from urine, undertook the task, and succeeded. It is on this account that the substance long went under the name of Kunkel’s phos- phorus. Mr. Boyle is also considered as one of the discoverers of phosphorus. He communicated the secret of the process for preparing it, to the Royal Society of London, in 1680. It is asserted indeed by Kraft, that he discovered the secret to Mr. Boyle, having, in the year 1678, carried a small piece of it to London, to shew it to the royal family; but there is little probabi- lity that such a man as Mr. Boyle would claim the discovery as his own, and communicate it to the Royal Society, if this had been the case. Mr. Boyle communicated the process to God- frey Hankwitz, an apothecary of London, who for many years supplied Europe with phosphorus, and hence it went under the name of English phosphorus. In the year 1774, the Swedish chemists, Gahn and Scheele, made the important discovery, that phosphorus is contained in the bones of animals, and they improved the processes for procuring it. The most convenient process for obtaining phosphorus, seems to be that recom- mended by Fourcroy and Vauquelin, which we shall transcribe. Take a quantity of burnt bones, and reduce them to powder. Put 100 parts of this powder into a porcelain or stone-ware bason, and dilute it with four times its weight of water. Forty parts of sulphuric acid are then to be added in small portions, taking care to stir the mixture after the addition of every por- tion. A violent effervescence takes place, and a great quantity of air is disengaged. Let the mixture remain for twenty-four hours, stirring it occasionally to expose every part of the pow- der to the action of the acid. The burnt bones consists of the phosphoric acid and lime, but the sulphuric acid has a greater affinity for the lime than the phosphoric acid. The action of the sulphuric acid uniting with the lime, and the separation of the phosphoric acid, occasion the effervescence. The sulphuric acid and the lime combine together, being insoluble, and fall to the bottom. Pour the whole mixture on a cloth filter, so that the liquid part, which is to be received in a porcelain vessel, may pass through. A white powder, which is the inso- luble sulphate of lime, remains on the filter. After this has been repeatedly washed with water, it may be thrown away; but the water is to be added to that part of the liquid which passed through the filter. Take a solution of sugar of lead in water, and pour it gradually into the liquid in the porcelain bason. A white powder falls to the bottom, and the sugar of lead must be added so long as any precipitation takes place. The whole is again to be poured upon a filter, and the white powder which remains, is to be well washed and dried. The dried powder is then to be mixed with one-sixth of its weight of charcoal powder. Put this mixture into an earthenware retort, and place it in a sand bath, with the beak plunged into a vessel of water. Apply heat, and let it be gradually in- creased till the retort becomes red-hot. As the heat increases, air-bubbles rush in abundance through the beak of the retort, some of which are inflamed when they come in contact with the air at the surface of the water. A substance at last drops out similar to melted wax, which congeals under the water. This is phosphorus. To have it quite pure, melt it in warm water, and strain it several times through a piece of shamoy leather, under the surface of the water. To mould it into sticks, take a glass funnel with a long tube, which must be stopped with a cork. Fill it with water, and put the phosphorus into it. Im- merse the funnel in boiling water, and when the phosphorus is melted, and flows into the tube of the funnel, then plunge it into cold water, and when the phosphorus has become solid remove the cork, and push the phosphorus from the mould with a piece of wood. Thus prepared, it must be preserved in wated tumour, of the same nature with the bubo. close vessels containing pure water. When phosphorus is perfectly pure it is semi-transparent, and has the consistence of wax. It is so soft that it may be cut with a knife. Its specific gravity is from 177 to 2-03. It has an acid and disa- greeable taste, and a peculiar smell, somewhat resembling garlic. When a stick of phosphorus is broken, it exhibits some appearance of crystallization. The crystals are needle-shaped, or long octahedrons; but to obtain them in their most perfect state, the surface of the phosphorus, just when it becomes solid, should be pierced, that the internal liquid phosphorus may flow out, and leave a cavity for their formation. When the phosphorus is exposed to the light, it becomes of a reddish colour, which appears to be an incipient combustion. It is, therefore, necessary to preserve it in a dark place. At the temperature of 90° it becomes liquid, and if air be entirely ex- cluded, it evaporates at 219°, and boils at 554°. At the tem. perature of 43° or 449 it gives out a white smoke, and is lumin- ous in the dark : this is a slow combustion of the phosphorus, which becomes more rapid as the temperature is raised. When phosphorus is heated to the temperature of 148° it takes fire, burns with a bright flame, and sends out a great quantity of white smoke. Phosphorus enters into combination with oxy- gen, azote, hydrogen, and carbon. Phosphorus is soluble in oils, and when thus dissolved, forms what has been called liquid phosphorus, which may be rubbed on the face and hands with- out injury. It dissolves too in ether, and a very beautiful experiment consists in pouring this phosphoric ether in small portions, and in a dark place, on the surface of hot water. The phosphoric matches consists of phosphorus extremely dry, minutely divided, and perhaps a little oxygenized. The sim- plest mode of making them, is to put a little phosphorus, dried by blotting paper, into a small phial ; heat the phial, and when the phosphorus is melted turn it round, so that the phosphorus may adhere to the sides. Cork the phial closely, and it is pre- pared. On putting a common sulphur match into a bottle, and stirring it about, the phosphorus will adhere to the match, and will take fire when brought out into the air. PHOSPHURETS, substances formed by an union of the alkalies, earths, and metallic oxides, with phosphorus. Thus we have phosphuret of lime, &c. PHOTOMETER, an instrument intended to indicate the different quantities of light, as in a cloudy or bright day, or between bodies illuminated in different degrees. In Leslie’s photometer, the essential part is a glass tube like a reversed syphon, whose two branches should be equal in height, and terminated by balls of equal diameter; one of the balls is of | black enamel, and the other of common glass, into which is put some liquid. The motion of the liquor, which is sulphuric acid tinged red with carmine, is measured by means of a graduation, the zero is situated towards the top of the branch that is terminated by the enamelled ball. The use of this in- strument is founded upon the principle, that when the light is absorbed by a body, it produces a heat proportional to the quantity of absorption. When the instrument is exposed to the solar rays, those rays that are absorbed by the dark colour heat the interior air, which causes the liquor to descend at first with rapidity in the corresponding branch. But as a part of the heat which had introduced itself by means of the absorp- tion is dissipated by the radiation, and as the difference be- tween the quantity of heat lost and that of the heat acquired goes on diminishing, there will be a point where, these two quantities having become equal, the instrument will be sta- tionary, and the intensity of the incident light is then estimated by the number of degrees which the liquor has run over. The author of this ingenious instrument has pointed out its advan- tages in determining the progressive augmentation undergone by the intensity of the light, and the gradation in a contrary sense which succeeds to that progress, both from the beginning of the day to its end, and from the winter solstice to the end of the succeeding autumn. With the help of such an instrument, one might also compare the action of the rays of light in differ- ent countries, of which some dart with sufficient constancy from a fine and serene sky, while others seem to be covered with a veil which dims and obscures their lustre. º PHY GETHLON, in Surgery, a broad but not much ele, P H Y P H Y S03 DICTIONARY OF MECHANICAL SCIENCE. PHYLACTERY, in Antiquity, a charm or amulet, which evils, diseases, and dangers. PHYSETER, Cachalot, a genus of fishes of the order cete. Physeter macrocephalus, blunt-headed cachalot. This whale, which is one of the largest species, is scarcely inferior in size to the great mysticete, often measuring sixty feet or more in length. The , head is of an enormous size, constituting more than a third of the whole animal; the mouth wide, the upper lip rounded, thick or high, and much broader than the lower; which is of a somewhat sharpish form, fitting in a manner into a longitudinal bed or groove in the upper. The teeth, at least the visible ones, are situated only in the lower jaw, and when the mouth is closed, are received into so many corresponding holes or cavities in the upper; they are pretty numerous, rather blunt, and of a somewhat conic form, with a very slight bend or inclination inwards. The front of the head is very abrupt, descending perpendicularly downwards; and on its top, which has been improperly termed the neck by some authors, is an elevation or angular prominence containing the spiracle, which appears externally simple, but is double within. The head is distinguished or separated from the body by a transverse fur- row or wrinkle. The eyes are small and black; and the ears or auditory passages extremely small. About the middle of the back is a kind of spurious fin, or dorsal tubercle, of a cal- lous nature, not moveable, or somewhat abrupt or cut off be- bind. The tongue is of the shape of the lower jaw, clay- coloured externally, and of a dull red within. The throat is but small in proportion to the animal. The body is cylindrical beyond the pectoral fins, growing narrower towards the tail. The colour of the whole animal is black, but when advanced in age grows whitish beneath. It swims swiftly, and is said to be a violent enemy to the squalus carcharias, or white shark, which is sometimes driven ashore in its endeavours to escape, and, according to Fabricius, will not venture to approach its enemy, even when dead, though fond of preying on other dead whales. It is in a vast cavity within the upper part of the head of this whale, that the substance called spermaceti is found, which, while fresh and in its natural receptacle, is nearly fluid; but when exposed to the air, concretes into opake masses: this substance being so universally known, it becomes unnecessary to describe it farther. A more curious and valuable production, the origin of which has long eluded the investigation of naturalists, is obtained from this animal, viz, the celebrated perfume called ambergris, which is found in large masses in the intestines, being in reality no other than the faeces. PHYSICAL, any thing relating to physics. PHYSICIANS. No person within London, nor within seven miles of the same, shall exercise as a physician or surgeon, except he is examined and approved by the bishop of London, or by the dean of St. Paul’s, calling to them four doctors of physic, and for surgery, other expert persons in that faculty, of them that have been approved, upon the pain of forfeiture for every month £5, one half to the king and the other half to any that will sue. One that has taken his degree of doctor of physic in either of the universities, may not prac- tise in London, and within seven miles of the same, without license from the college of physicians. PHYSICO MATHEMATIcs, is the same as mixed mathema- tics, being those branches of this science which investigates the laws and actions of bodies, and their combinations, by means of certain data drawn from observation and experiment. PHYSICS, is a term denoting the same as experimental or natural philosophy; being the doctrine of natural bodies, their phenomena, causes, and effects, with their various affections, motions, and operations. Experimental PHYSICs, is that which inquires into the nature and reason of things by experiments, as in hydrostatics, pneu- matics, optics, chemistry, &c. - . Mechanical PHYSICs, explains the appearances of nature from several parts, according to the established laws of nature. PHYSIQGNOMY, is the peculiar combination of features, which, designates the feelings and dispositions of the mind. distinctive marks, in the form of the head and the outlines of being worn, was supposed to preserve people from certain | the countenance, is visible to the most inattentive observer: and it is well known, that those marks insensibly lead us to form conclusions as to the nature and inclinations of persons to whom we are introduced for the first time, which may some- times be correct, but are frequently erroneous. Admitting this fact, as to mankind in general, it will be proper to ob- serve, that however the study of physiognomy may be com- mended and recommended, it should be exercised with great discretion and judgment, or very fatal, or, at least very dis- agreeable, consequences may be the result; for it must be remembered, that numerous causes exist to derange and dis- compose the human frame during infancy, and even before the birth, which may impress a character or expression on the fea- tures, descriptive of evil passions that never existed in the mind of the unfortunate person so situated; for instance, it would be inhuman to judge of the soul of one who has had the vertebrae of his back doubled, from the expression of his face, which is uniformly that of peevishness and confirmed ill- nature; nor would it be just to think a man capable of every kind of wickedness, whose head and face bear the marks of malice, through a deformity existing perhaps before his birth. | Were the bones incompressible from the instant they are formed, and the muscles incapable of being moulded to their shape, in short, did mankind receive a decided and unalterable outline from the Creator, we should then make correct conclu- sions from the beauty or irregularity of the face. The aid of Lavater is not necessary to inform us that there exists a national physiognomy, by which a stranger in any given coun- try may be known by those who are possessed of previous observation, to be a Spaniard, a German, or a Frenchman, and which impels even the very vulgar to exclaim, “He is a foreigner,” though they cannot appropriate him to his country. After all, it will be admitted that this science, if such it can fairly be denominated, must be precarious, and, in some re- spects, delusive. It cannot, however, be doubted, that there is an apparent correspondence between the face and the mind: the features and lineaments of the one are directed by the motions and affections of the other; there is, perhaps, even a peculiar arrangement of the members of the face, and a peculiar disposition of the countenance to each particular affection of the mind. PHYSIOLOGY, is the science which treats of the powers that actuate the component parts of living animal bodies, and of the functions which those bodies execute. The life of a body is better known by observation than can be described by words. If it be possible to give a sort of definition of it, the following is as true as it will admit of: that life tends by an universal sympathy, or assimilating action, to produce another body similar to itself. This sympathy seems to exist between the circulating and the nervous systems; as for instance, in order that sensibility may be acute (or secretion performed) a very extensive circulation, and an equally diffuse distribution of nerves, is necessary. We may conveniently consider the nervous system as consisting of the brain, spinal cord, and nerves; and the vascular system as consisting of arteries, veins, absorbents and exhalants, universal ; while the others, as the respiratory, nutritive, generative, and those of waste, may be called partial systems. The nervous system especially tends, from its supplying us with sensibility and heat, to oppose the processes consequent to mere matter. The brain is the organ of the mind. The cerebral lobes are the seat of sensa- tion and volition. The cerebellum regulates the actions of running, walking, standing, flying, &c. The spinal cord, with the medulla oblongata, corpora quadrigemina, and nerves, are the seat of those impressions which give rise to muscular con- tractions; and the spinal cord combines or generalizes the contractions, so as to produce motion of the joints. The spinal | cord seems to be formed previous to the development of the | brain, and is so necessary to life that few animals want it, and | is perfect in proportion as their organization is perfect. the matter, motion, structure, and figures of bodies, and their The human species is endowed with three sorts of nerves, viz. 1. Those of the different external senses. 2. Those requisite for motion. 3. Those necessary to the supply and waste of the machine. The contraction of both sides of the heart takes That every individual of the human race possesses a set of place at the same time. Arteries are conical tubes, whose base 804 P 1 E P H Y - DICTIONARY OF MECHANICAL SCIENCE. originates from the heart; they have a tonic power depending on their degree of life, the vessels are constantly full of blood, so that the quantity sent out from the ventricle merely acts as a jet upon the mass already in the arteries, and gives to the containing vessels a sort of motion. The blood in the veins is urged on partly by the power behind, and also by a species of suction exerted from the right side of the heart. The general circulation may be thus described: all the blood, except that of the lungs, is brought to the right auricle, and compressed into the right ventricle to be circulated through the lungs, whence it is returned by the pulmonary veins to the left auricle, thence sent into the left ventricle, to be distributed through the whole body, except the lungs. The blood, in passing through the lungs loses that dark colour acquired from its tardy transmis- sion by the veins, the change is most probably decarbonization, and is necessary to the healthy action of the heart. Some peculiarities may be noticed relating to the circulation; the connexion of the circulation in the genital organs and mamma. That of the liver which is entirely venous, and consisting of the blood which had been distributed to the organs of digestion, collected into a large vein, (vena portae,) which again ramifies itself like an artery through the substance of the liver. Again the circulation through the brain is by arteries terminating in sinuses, and upon the principle of the syphon. The absorbents, as constituting part of the vascular system, may be arranged into two classes; those which absorb a fluid necessary to the nutrition of the body, and those which admit of grosser sub- stances. The first are those which arise from the stomach and intestinal canal, and terminate in the thoracic duct to enter the venous system by the subclavians. The others are spread over the whole body, and enter the veins in their neighbourhood: each of those sets has a sort of elective power. Of the partial Systems:—The external senses, sight, hearing, taste, smell, and touch, depend upon a proportional increase of the universal systems. Respiration is essential to the main- tenance of the circulation, the lungs are full of cells into which there is an exhalation from the arteries ramified on them, it is here where the blood becomes decarbonated, or, as some would have it, oxygenated. Absorption is exceedingly quick in them. The action of the lungs may be compared to the action of two bladders within a bellows, and fitted by means of a common communication to the tube of the bellows, no air being ad- mitted by the tube or usual hole into the cavity of the bellows external to the bladder. Another important use of the lungs is by its forcible emission of air through the glottis, producing voice, which, modified by the tongue, palate, teeth, and lips, furnishes us with the power of articulation. We may now consider the circle of organs engaged in nutrition or supply and waste. There is a sympathy extending along the whole range of these organs, viz. the mouth, gullet, stomach, and spleen, intestines, and liver, and pancreas; so that if any thing should be conveyed into the stomach, even without the action of the mouth, a secretion of saliva would take place, &c. Alimentation commences with the mastication of the food, during which action it is mixed with saliva, it is then swallowed, mixed with the gastric juice in the stomach, converted into a mass called chyme, thence passes into the bowels; coming in contact with the biliary and pancreatic secretions, it is sepa- rated into two substances, one named chyle, which is to be absorbed for the nutrition of the frame, the other to be evacu- ated. Hunger arises from the action of the gastric juice on the coats of the stomach.-The foetus is not part of the body of the mother, but derives its own nourishment as a distinct ani- mal by its own mechanism. Its mechanism serves only for its nourishment, being an imperfect animal, and not enjoying any of the external senses. The circulation of the blood in the foetus is different. The blood from the umbilical vein partly passes through the liver, partly by the ductus venosus, into the vena cava, thence to the right auricle, the right auricle throws it partly into the right ventricle, but the greater part through the foramen ovale into the left auricle. The portion sent to the right ventricle is transmitted through the pul- monary artery to the lungs in part, and also by the canalis arteriosus into the aorta. The blood which the pulmonary veins bring into the left auricle passes with that through the foramen ovale into the left ventricle, to be transmitted through - the aorta to the whole system. The urinary system serves to throw off the urea from the circulation, consequently a mere organ of waste. - PHYTOLOGY, a discourse concerning the kinds and virtues of plants. > A . • - . PHYTOTAMA, a genus of birds of the order passeres; There is only a single species, viz. P. rara, that inhabits Chili. PIASTER, a Spanish coin of the value of 4s. 6d. sterling. PIAZZA, in Architecture, is a portico, or covered walk supported by arches; and all walks with porticos around them, are piazzas, as the fine walks around the Royal Exchange, London, one of the most classical and yet national monuments to be found in Europe. - - PICAE, the second order of birds, according to the Linnaean system. The male feeds the female while she is sitting. They live in pairs. Of this order there are twenty-six genera. PICARD, Joh N, a celebrated French mathematician and astronomer of the 17th century, was the first who applied the telescope to astronomical instruments, and commenced the publication of the “Connaissance des Tems,” which he calcu- lated from 1679 to 1683. He also first measured the length of a degree of the meridian in France, and gave a map of that country. The time of his birth is not known, but he died in 1682 or 1683. Picard was author of several works on Level- ling, Dialling, Dioptrics, Discharge and Mensuration of Fluids, Astronomy, &c., the whole of which are given in the 6th and 7th volumes of the Memoirs of the Academy of Sciences. PICKETS, in Fortification, sharp stakes about three feet long, sometimes shod with iron, used in laying out ground. But when used for pinning the fascines of a battery, they are from three to five feet long. In the Artillery, pickets five feet long, are used to pin the park lines; in the camp, they are used about eight inches long, to fix the tent cords; or five feet long in the cavalry camp, to fasten the horses. PICRANIA AMARA, a bitter wood of Jamaica, belonging to the pentandria class of plants. The tree is tall, its timber beautiful, but every part of it is intensely bitter; and in cabi- net work it is invaluable, as no insect will live near it. How excellent then for beds ! This tree has a great affinity to the quassia amara of Linnaeus, in lieu of which, it is used as an antiseptic in putrid fevers. - • PICQUET, a celebrated game at cards played between two persons, with only thirty-two cards; all the twos, threes, fours, fives, and sixes, being set aside. PICUS, the Wood-pecker, in Natural History, a genus of birds of the order Picae. These birds live principally upon insects, to obtain which they climb trees, and are perpetually in search of those crevices in which their food is lodged: there are fifty species. The greatest black wood-pecker, abounds in Germany, and builds in ash and poplar trees, which they are said to excavate speedily, so as to expose them to be blown down by winds which would not otherwise have affected them ; under the hole made by these birds may be often found several pecks of dust and pieces of wood. They are of the size of a jackdaw. The green wood-pecker, is the largest species in Great Britain, and is thirteen inches long. These birds are more frequently seen on the ground than the other species, particularly where ant-hills abound, the population of which they almost extirpate by their incessant efforts. The witwall, is nine inches long, and strikes with far greater comparative force against the trees than any of the tribe. PIEPOUDRE, Court of, the lowest, and at the same time the most expeditious, court of justice known to the law of England. It is called piepoudre (curia pedis pulverisati) from the dusty feet of the suitors. But the etymology given us by a learned modern writer is much more ingenious and satisfactory; it being derived, according to him, from pied puldreaux, “a pedlar,” in old French, and therefore, signifying the court of such petty chapmen as resort to fairs or markets. It is a court of record, incident to every fair and market; of which the steward of him who owns or holds the toll of the market is the judge. It was instituted to administer justice for all com- mercial injuries done in that very fair or market, and not in any preceding one ; so that the injury must be done, com- plained of, heard, and determined, within the compass of one and the same day, unless the fair continues longer. % º - Aº, ºn - / º º, Zºº º - Van/oves ZºZº. Zºe. Złºcº //e Zºne. | Tim | º - - | | º º º S. º º ſ |-|- º | -- º | - - | | - | - | | L. * º º º º |||||||||||| | | Zºº Zºº ///º/, /º/” Aº. 3. 12 ºf 2/ -ºº º - ... . . . . . | ". ºlº by ºr --- T //, / ºz/, //// Zºº ºn ºr - | | - . - - - an all - - - - - - - ºf º ºf . |CUT Eſ - CU - - º º, . . . .” º º º º - - i --- i T ſº ſº ºwe ºr ſº lºw a ſº ºw. - * / / /32. | T. º | | - - º --- º - --- i - - A/ººn ºr ºn sº ſº ºr ſº ºn º º - - - |-- –EE - __ | |TF ºffl –ea-Tºſſ --~ llllllllllllllllllllllllllllllllllllllllllllllllllllllllllliºtti-E-Fºſſ | P I E P I L 805 DICTIONARY OF MECHANICAL SCIENCE. . PIER, a strong mound or fence, projecting into the sea, to break off the violence of the waves from the entrance of a har- bour. & . - . PIERS, in the theory of Bridges, are the walls built to sup- port the arches, and from which they spring as bases. . . Piers and Suspension Bridges. (See Plate.)—In nothing per- haps do the French shew their enmity of the British, more than in depreciating our inventions, and in appropriating to them- selves, or assigning to others, plans, discoveries, inventions, and improvements, exclusively British. We are led to this introductory remark by an assertion of Dupin, in his Treatise on the Commercial Power of Great Britain, in which he says, that from North America the noble application of iron to chain bridges was soon transferred to Europe, vol. i. p. 370. Again the French baron tells us, p. 374, “The Americans commenced their constructions about the end of the last century,” i. e. about thirty years ago, reckoning from 1826, the period when we published letter P of our Dictionary. . Now it is in print, in opposition to Dupin's assertion, that for a long time the Europeans have had an idea of suspension bridges, as may be seen in the bridges described in the work that Faustus Varentius published in 1625; and “80 years ago,” (says Dupin very unguardedly for his admiration of the Ame- ricans.) “ the English threw over the Tees at Winch, near Durham, a bridge of iron wire, which served for foot passengers. The Chinese and Peruvians seem to have been the fi:st nations that used suspension bridges; but those of the latter kept the catenarian bend, and the roads they afforded were very incon- venient in their passage. - To Capt. Brown, of the British navy, we are indebted for the idea and execution of suspension and chain piers, of consider- able length, in ports and on shores, where ships are unable to approach the beach for a great distance, even at high water. For the embarkation of troops, cavalry horses, baggage, and munitions of war, these suspension piers are very useful. In 1821, Capt. Brown exhibited the first model of these new con- structions at Leith. In order to reach, from the shore, the place in the Forth where ships could keep afloat without dan- ger at high or low water, and in very bad weather, it was necessary to advance 233 yards into the sea, reckoning the distance from the high-water mark on shore. To fill up this long space, three arches of suspension chains were formed, each having 249 feet in span; thus the pier is held by four supports only,–one on shore, and three upon piles in the middle of the Sea. To describe this work systematically, we will mention, in succession, the piers, the abutments; the suspension chains, and the flooring or road way. - . Piers and Abutments.—The principal pier is that which is at the head of the chain pier; it is formed by six rows of piles, having the same direction with the suspension chains; cross timbers consolidate the part above water, the summit of which leaves a flooring or platform of wood. This platform has a hatchway leading to a flight of stairs, descending as low as the level of low water. A plank thrown across, from the last step to the steam-boats, or other vessels, near the landing pier, enables people either to land or to embark. The two interme- diate piers, between the shore and the landing place, are formed with piles, so planted as to represent a lozenge; they are covered with a platform, upon which rest the iron bench which bears the suspension chains. To serve as a common support to these chains and their wards, a stone pillar has been built upon the shore, having twenty feet in height upon a square base, six feet on each side; from the top of this pillar or sup- port, the chains, or land-wards, with an inclination of about forty-five degrees, reach the ground, in which they penetrate to a depth of about ten feet, where they are fixed by means of cast-iron ballast plates, in a manner similar to those used by Capt. Brown in the suspension bridge thrown by him across the Tweed. On the side of the landing platform, each of the chains has likewise an inclination of forty-five degrees, and is attached to one of the piles supporting it. Shores, placed obliquely, serve the purpose of resisting the great strains experienced by the chains. The benches used to support the chains, whether seen longitudinally or ‘transversely, are made of iron, open, but combining, nevertheless, lightness with solidity. At the summit they are attached to two oblique suspending : rods, supporting both the landing pier and the flooring. * 3. - Suspension Chains, &c.—The suspension chains, as to their form, and the joining together of the parts composing them, resemble those used in the construction of the Union Bridge upon the Tweed ; they differ in one point only—the links, which are close to the points of support, having to bear a greater weight, are made thicker than those placed in the middle of the chains. The suspending rods are round, except the lower end, where they fork, in order to receive the flat iron, or lath, which runs along the whole length of the chain pier, and upon which the end of the beams supporting the flooring are rest- ing; the planks forming this flooring are two inches thick. On each side of the pier is a cornice, which covers over the ends of the beams; the parapet is made of iron, four feet high, and firmly joined with the suspending rods. . . . In order to try the power of this chain pier, Capt. Brown, as soon as it was terminated, loaded it with the immense weight of 210 tons, which he suffered to remain for a great length of time, notwithstanding the casual burden occasioned by passen- gers, and the shaking produced by their movement. No part of the erection has been observed to suffer from the movements, or by the great strains produced on the chains by so great a burden. Such a fact affords the most satisfactory proof as to the solidity of this system of chain landing piers. - At Brighton, a handsome chain pier is now erected also, but on a scale much more extensive than the Leith pier; it being composed of three inverted arches, having each 230 feet of span ; its width is about 12 or 14 feet. & PIG OF BALLAST, a large mass of cast iron or lead, used for ballast. , - x- PIGEONS. Every person who shall shoot at, kill, or de- stroy a pigeon, may be committed to the common jail for three months, by two justices of the peace, or pay 20s. to the poor. 1 Jac. 1. c. 27. - - - PIKE, an offensive weapon, consisting of a shaft of wood, twelve or fourteen feet long, headed with a flat-pointed steel, called the spear. - ... ." PIKE, or Jack, a fish ; see Esox, p. 276. PILASTER. See ARCHITECTURE. - PILE, in Artillery, denotes a collection or heap of balls or shells, piled up in a pyramidal form, the base being some regu- . lar figure, as an equilateral triangle, square, or rectangle, and the whole pile a series of such figures, the side of each succes- sive row diminishing by one from the bottom upwards. The e- fore the whole number of balls is equal to the sum of a series of triangular numbers, squares, or rectangles, according to the figure of the pile, by experiment. The algebraic formulae are difficult to remember upon an emergency ; and therefore the following general rule, for this purpose, which is not commonly known, is deserving the notice of artillery officers. Rule.—In every pile there may be found three parallel lines, the sum of which multiplied by the number of balls in the trian- gular face of the pile, and divided by 3, is the number of balls. In the rectangular pile, the three parallel lines are the two bot- tom rows in length, and the upper ridge of the pile ; and the face the triangular end. In the square pile, any two opposite sides of the square base, and the upper ball, are three parallel lines. And in the triangle pile, one side of the bottom row, the opposite extreme ball, and the upper ball, are the three paral- lel sides; the face in both these cases being any of the equal slant sides of the pile. . Pi Le, in Coinage, denotes a kind of puncheon, which in the old way of coining with the hammer, contained the arms, or other figure and inscription, to be struck on the coin. Piles, in Building, are large stakes or beams sharpened at the end, and shod with iron, to be driven into the ground for a foundation to build upon in marshy places. Pile Engine, is an engine used for driving piles. - Vauloue's Pile Engine. (See Plate.)—The horses which work this engine are yoked at SS, and by moving the wheel B and drum C, which are locked together, raise the follower G. H., (carrying the ram Q by the handle R), by means of the rope H H, which coils round the drum. When the follower G reaches the top of the frame, the upper legs of the tongs H are closed by press- ing against the adjacent beams: and their lower legs are 9 T { 806 P I L P I L, DICTIONARY OF MECHANIAAL SCIENCE. opened, so that they drop the ram Q, which falls and strikes the pile. When G is at the top of the frame, the crooked han- ‘dle 6, of the follower G, presses against the cords a, a, which raise the end of the lever L (see fig 2.) round m as a centre, and by depressing the extremity N, and consequently the bar S, S, unlock the drum C and the wheel B, so that the follower G falls by its weight and seizes the ram R. As soon as the fol- lower drops, the horses would tumble down, having no resist- ance to overcome, were not this prevented by the fly O, which is moved by the wheel B and trundle X, and opposes a suffi- .cient resistance to the horses till the follower again seizes the ram. When the follower falls, the weight L (fig. 2.) pushes up ...the bolt Y into the drum C, and locks the wheel and the drum; and the same operation is afterwards repeated. Bunce's Pile Engine. See Plate.—A side view of this engine is shewn in fig. 3, 4. It consists of two endless ropes or chains A, connected by cross pieces of iron B, B, &c. (fig. 4,) which pass round the wheel C, the cross pieces falling into corre- sponding cross grooves, cut in the periphery of the wheel. When the man at S, therefore, drives the wheel m by means of the pinion p, he moves also the wheel C fixed on the axis of m, and makes the double ropes revolve upon the wheels, C, D. The wheel D is fixed at the end of a lever D H K, whose centre of motion is H, a fixed point in the beam F.T. Now when the ram L (fig. 3, 5.) is fixed to one of the cross pieces B by the hook M, the weight of the ram acting by the rope, moves the lever D K round H, and brings the wheel D to G, so that by turning the winch, the ram L (fig. 3.) is raised in the vertical line L. R. G. But when it reaches R, the projecting piece R disengages the ram from the cross piece B, by striking the bar Q ; and as the weight is remcved from the extremity D of the lever, the counterpoise I brings it back from G to its old position at F, and the ram falls without interfering with the chain. When the hook is descending, it is prevented from catching the rope by means of the piece of wood N suspended from the hook M at O; for being specifically lighter than the iron weight L, and moving with less velocity, it does not come in contact with L till the ram is stopped at the end of its path. When N, therefore, falls upon L, it depresses the extremity M of the book, and therefore brings the hoop over one of the cross pieces B, by which the ram is again raised. The pile engine offers a remarkable confirmation of the doc- trine of percussion, proving that, physically speaking, we may balance any percussive force by an equivalent one of mere pressure, or even we may make the latter greater so as to over- come the former. It has, for instance, been found, that in driv- ing piles in a uniform sandy oil of the same density to 47 feet, the piles could not be driven more than 15 feet by any percus- sive blow that could be communišated by the engine; that is, the friction and resistance of the soil which may be con- sidered as a pressive force, was greater than any percus- sion force that could be employed by the pile engine, although the rammers made use of were extremely great. And hence when we are computing the effect of a pile engine, it will be necessary to estimate first the quantity of percussion that is equivalent to the resistance and friction opposed to the pile ; , as no momentum short of this, or even just equal to it, will produce any effect, and when the momentum is greater than this, it is only the difference between the two that is effective in producing motion in the pile. And to this circumstance must be attributed the many erroneous solutions that appeared a few years back to the question, “What must be the height of a pile engine to produce the greatest effect in a given time !” This question, at first sight, appears to be the same with asking how high must the pile engine be to produce the greatest mo– mentum in a given time; but using this principle, the solution always gave the height = 0; that is, the greatest effect will be produced when the rammer is left at rest on the top of the pile. But if instead of proceeding thus, we first estimate, or find from experiment, the height to which the rammer, must be drawn, in order that its momentum may be equivalent to the resistance of the pile, and then considering the difference between this and any greater momentum to be only the effective part, a very #. solution will be obtained. But before entering upon the solution of this problem, it will be proper to offer a few far- ther remarks with regard to the comparability of percussion and pressure, because the solution ultimately depends upon a proper comparison of those quantities, and a want of due attem- tion to which seems to have been the cause of the erroneous results generally deduced in the solution of this problem. With- out, indeed, entering into a discussion concerning the congruity or incongruity of these forces, it is obvious that they may be so employed as to produce the same or equal results. A nail, for example, may be driven to a certain depth into a block of wood by the blow of a hammer, or it may be sunk to the same depth by the pressure of a heavy body; whence, and from nu- merous other instances, it is obvious that pressure and percus- sion, whether congruous or incongruous in their mature, are at least comparable in their effects. With regard to the above problem, the resistance and friction of the soil against the pile may, as above observed, be considered as a pressure, and the object of our inquiry is, to establish a comparison between this resistance and pressure of the soil, and the momentum of the ram, or what part of the whole generated momentum of the lat- ter is employed in overcoming the resistance of the former, in order to determine the effective part of the stroke, which ought alone to be considered in estimating the maximum effect; be- cause any single momentum, less than that which is equivalent to the resistance, would produce no effect whatever. Now it being admitted that pressure and momentum are at least com- parable in their effects, it must also be granted that there is some determinate momentum of the ram equivalent to the re- sistance of the pile; and the height necessary for producing this momentum must be the first object of our research, which it is obvious, from various circumstances that may arise in the appli- cation of the engine, can only be determined by experiment. . . PILLOW, a block of timber whereon the inner end of the bowsprit is supported. - - PILOT, the officer who superintends the navigation, either upon the sea coast or upon the main ocean. It is, however, more particularly applied to the person charged with the ship's course on or near the sea-coast, and into the roads, rivers, bays, havens, &c. within his particular district. The regulations with regard to pilots in the royal navy are as follow :—The commanders of the king’s ships, in order to give all reasonable encouragement to so useful a body of men as pilots, and to remove all objections to his majesty’s service, are strictiy charged to treat them with good usage, and an equal respect with warrant officers. The purser of the ship is always to have a set of bedding provided on board for the pilots, and the cap- tain is to order the boatswain to supply them with hammocks, and a convenient place to lie in near their duty, and apart from the common men; which bedding and hammocks are to be returned when the pilots leave the ship. A pilot, when con- ducting one of his majesty’s ships in pilot water, shall have the sole charge and command of the ship, and may give orders for steering; setting, trimming, or furling the sails; tacking the ship, or whatever concerns the navigation; and the captain is to take care that all the officers and crew obey his orders. But the captain is diligently to observe the conduct of the pilot, and if he judges him to behave so ill as to bring the ship into dan- ger, he may remove him from the command and charge of the ship, and take such measures for her preservation as shall be judged necessary; remarking upon the log book the exact hour and time when the pilot was removed from his office, and the reasons assigned for it. Captains of the king’s ships employing pilots in foreign parts of his majesty’s dominions, shall, after performance of the service, give a certificate thereof to the pilot, which being produced to the proper naval officer, he shall cause the same to be immediately paid ; but if there be no naval offi- cer there, the captain 6f his majesty’s ship shall pay him, and send him the proper vouchers, with his bill, to the navy board, in order to be paid as bills of exchange. Captains of his ma- jesty’s ships employing foreign pilots to carry the ships they command into or out of foreign ports, shall pay them the rates due by the establishment or custom of the country, before they discharge them ; whose receipts being duly vouched, and sent with a certificate of the service performed to the navy board, they shall cause them to be paid with the same exactness as they do bills of exchange. - Branch Pilot, is one who is duly authorized by the Trinity Board to pilot ships up particular channels or rivers. - * P I N P I N DICTIONARY OF MECHANICAL SCIENCE. 807 ... PIMENTO, Jamaica pepper, or allspice. See MYRTUs. PIN, in Commerce, a little necessary instrument made of brass wire, chiefly used by women in adjusting their dress. When the wire is received at the manufactory, it is wound off from one wheel to another, and passed through a circle of a smaller diameter in a piece of iron. When reduced to its proper size, it is straightened by drawing it between iron pins, fixed in a board in a zigzag manner. It is afterwards cut into lengths of about four yards, and then into smaller pieces, every length being sufficient for six pins. Each end of these is ground to a point. This operation is performed by boys, who each sit with two small grindstones before him turned by a wheel. Taking up a handful, he applies the wires to the coarsest of the two stones, moving them round that the points may not become flat. He then gives them a smoother and sharper point on the other stone: a lad of 12 years of age can point 16,000 in an hour. When the wire is pointed, a pin is taken off from each end, till it is cut into six pieces. The next operation is to form the heads or head-spinnings, as it is termed. This is done by a spinning wheel: one piece of wire is with rapidity wound round another; and the interior one being drawn out, leaves a hollow tube between the circumvolutions. It is then cut by shears, every two turns of the wire forming one head. These are soft- tened by throwing them into iron pans, and placing them in a furnace till they are red hot. As soon as they are cold, they are distributed to children, who sit with anvils and hammers before them. These they work, with their feet by means of a lathe. They take up one of the lengths, and thrust the blunt end into a quantity of the heads which lie before them; catching one at the extremity, they apply it immediately to the anvil and hammer, and by a motion or two of the foot, the point and the head is fixed together in much less time than can be described, and with a dexterity that can only be ac- quired by practice. The pins are thrown into a copper con- taining a solution of tin and wine lees. Here they remain for some time, and when taken out assume a dull white appearance: in order to give them a polish, they are put into a tub contain- ing a quantity of bran, which is set in motion by turning a shaft that runs through its centre, and thus, by means of friction, the pins become entirely bright. They are now separated from the bran, which is performed by a mode exactly similar to the win- nowing of corn; the bran flying off, and leaving the pin behind it fit for sale. - - - Needles are made of steel. The first thing in the manufac- ture of needles, is to pass the steel through a coal fire, and un- der a hammer to bring it to a round form, then it is drawn through, a large hole of a wire-drawing iron, and returned into the fire, and again drawn through a second hole smaller than the first, and thus successively till it has acquired a degree of fineness requisite; observing every time it is drawn to rub it with lard to render it more manageable. The steel thus reduced, is cut to the proper length of the needles; these pieces are flattened at one end to form the eye ; they are then put into a fire.to soften ; then taken out, and the head pierced by a puncheon of well-tempered steel, and laid on a leaden block, to bring out, with another puncheon, the little piece of steel re- maining in the eye. The corners of the heads are then filed off, and a little cavity filed on each side of the flat of the head, the point is then, formed with a ſile, and the whole is filed over. They are then laid on a long narrow iron, crooked on one end, to heat red-hot, with charcoal fire; when taken out, are thrown into a bason of cold water to harden. On this operation much depends; too much heat burns them, too little leaves them soft; experience teaches the medium. When thus hardened, they are laid in a shovel on a fire more or less brisk. This tempers them, and takes off their brittleness. They are then straightened one after another with a hammer. The next process is the po- lishing. The people take 12 or 15,000 needles, and range them in little heaps on a piece of new buckram sprinkled with emery dust; they are then sprinkled with oil of olives. The whole is then made up in a roll, and laid on a polishing table : a thick plank is now passed over the whole, and the needles within become polished. They are then washed in water with soap, and wiped in bran. The good are taken from the bad; the points are tipped with an emery stone turned by a wheel, and then packed up in parcels of 250 each for sale. | PIN of A Block, "is the axis on which the sheaves revolve being supported by the shell. Belaying PINs, pieces of wood or iron fixed in a kind of rail for making fast the small running. rigging. PINCHBECK, a factitious metallic substance, being an alloy of zinc three parts, and of copper four. PINE, the Fir Tree. Its timber, under the name of deal, is employed as wood-work for the building of houses; for rafters, flóoring, doors, the frames of windows, tables, boxes, and other purposes infinitely too various to be enumerated. Frigates, and other ships of large size, have sometimes been constructed of deal; but these are by no means-so durable as those built of oak. . Much of the deal which we use is imported into this country from Norway, and other northern parts of Europe. That from Christiana, which in London is called yellow deal, and in the country red deal, is frequently brought over in planks, but more commonly in boards about ten inches and half in width. . The Scots fir raised in England is equal to the foreign wood in weight and durability, but its grain is generally coarser. We are informed that in some parts of Ireland the bogs are almost entirely filled with the old roots of the Scots fir; and that these are dug up and converted into ropes, which, for sustaining moisture without decay, are found preferable to ropes made of hemp. The outer bark of the fir-tree may be used in the tanning of leather; and it is said that in the northern parts of Europe the soft, white, and fibrous inner bark is, in in times of scarcity, made into a kind of bread. For this pur- pose it is dried over a fire, reduced to powder, kneaded with - water and a small portion of corn flour into cakes, and baked. in an oven. Children in Norway are very fond of the fresh bark in the spring of the year, either shaved off with a knife or grated with a rasp. - Common turpentine is the resinous juice chiefly of the Scots fir, obtained by boring holes into the trunks of the trees early in spring, and placing vessels beneath for its reception. It is of a brown colour, and has a strong odour and disagreeable taste. On the distillation of turpentine, an essential oil is pro- duced, called oil of turpentine, which is extremely pungent. When the distillation is continued to dryness, that which is left behind is known by the name of common resin or rosin; but if water be mixed with it while yet fluid, and incorporated by violent agitation, a substance is formed called yellow resin. Common turpentine is mostly employed as an ingredient in the plasters used by farriers. The oil is occasionally used in me- dicine ; and lately it has been considered efficacious in cases of worms. It is much employed by painters for rendering their colours more fluid ; as well as in the composition of different kinds of varnish used in floor-cloth, umbrella, and other manu- factures. The noxious spirit called gin was formerly flavoured with juniper berries; but as these are now too expensive, oil of turpentine, the taste of which in a slight degree resembles that of juniper, is applied to the same purpose; and very con- siderable quantities of turpentine are thus consumed. The common resin is used in plasters, for which its great adhesive- ness renders it peculiarly applicable. It is also of considerable importance in the arts ; and musicians rub the bows and strings of violins with it, to take off the greasy particles which are there collected, as well as to counteract the effects of moisture. Yel- low resin is used in plasters, and for other purposes in medicine. Tar is obtained from the roots and refuse parts of the fir-trec by cutting them into billets, piling these in a proper manner in pits or ovens formed for the purpose, covering them partly over, and setting them on fire. During the burning, a black and thick matter, which is the tar, falls to the bottom, and is conducted thence into vessels which are placed to receive it, and from which it is afterwards poured into barrels for sale. Tar is an article of great utility in manufactures, and for various economical purposes. It is much employed for smearing the rigging and other external parts of ships, to prevent their receiving injury from moisture. It has been used in medicine both internally and externally; and particularly tar water, or water impregnated with tar. . . ." - - - The Weymouth PINE, is chiefly distinguished...by its leaves growing in fives: and its cones being smooth, cylindrical, an longer than the leaves. This species grows wild in North Ame{ rica, and succeeds well in strong land in England. Its tim-i- * 808. P I P P I R. DICTIONARY OF MECHANIAAL SCIENCE. ber is white, of more open grain than Scots fir, and not so heavy as that. In America it is principally used for the masts of ships, for which by its toughness it is peculiarly calculated. The Scotch Fir, PINUs Sylvest Ris, a very useful tree in plantations for protecting other more tender sorts when young. It is also now very valuable as timber :—necessity, the common parent of invention, has taught our countrymen its value. When foreign deal was worth twenty pounds per load, they contrived to raise the price of this to about nine or ten pounds, and it was then thought proper for use; before, which period, and when it could be bought for little money, it was deemed only fit for fuel. On the South Downs some plantations of this tree, which have been sold after twenty-five years’ growth, at a price which averaged a profit of twenty shillings per annum per acre, on land usually let for sheep-pasture at one shilling and six- ©ll CC, p The Spruce Fir, PINUs ABIes, a native of Norway, and other northern parts of Europe, is known by its short and four-sided leaves, growing singly, and surrounding the branches, its cones being cylindrical, the scales somewhat square, flattened and notched at the top. The wood of the spruce fir is what the English carpenters usually denominate white deal. It is con- sidered next in value to that obtained from the Scots fir; and is remarkable for having few knots. On account of its light- ness, it is peculiarly adapted for packing cases and musical instruments. - - PINION, in Mechanics, an arbor or spindle, in the body of which are several notches, which catch the teeth of a wheel that serves to turn it round; or it is a lesser wheel that plays in the teeth of a larger one. - PINK, a vessel used at sea, masted and rigged like other ships, only that this is built with a round stern ; the bends and ribs compassing so as that her ribs bulge out very much. This disposition renders the pinks difficult to be boarded, and also enables them to carry greater burdens than others, for which purpose they are often used. PINNA, in Zöology, a genus belonging to the order of ver- nues testacea. The animal is a slug. PINNACE, a small vessel used at sea, with a square stern, having sails and oars, and carrying three masts, chiefly used as a scout for intelligence, and for landing of men, &c. One of the boats belonging to a great man of war, serving to carry the officers to and from the shore, is also called the innace. " . PINNACLE, in Architecture, the top or roof of a house ...te minating in a point. PINTLES, certain pins or hooks fastened upon the back part of the rudder, with their points downwards, in order to enter into and rest upon the googings fixed on the stern post to sup- port the rudder. See the article HELM. - PIN US, the Fir. See PINE. PIONEERS, in the art of war, are such as are commanded in from the country, to march with an army for mending the ways, for working on entrenchments and fortifications, and for making mines and approaches. - PIP, or PEP, pepia, a disease among poultry, consisting of a white thin skin, or film, that grows under the tip of the tongue, and hinders their feeding. - PIPE, in Law, a roll in the Exchequer, otherwise called the Great Roll. PIPE also denotes a vessel or measure for wine, containing 126 gallons. Pipe Office, is an office wherein a person, called the clerk of the pipe, makes out leases of crown lands, by warrant from the lord treasurer, or conmissioners of the treasury, or chancellor of the exchequer. The clerk of the pipe makes out also accounts of sheriffs, &c. and gives the accomptants their quietus est. PIPER, Pepper, a genus of the trigynia order, in the dian- dria class of plants. There is no calix or corolla; the berry is one-seeded. There are 60 species. PIPES, for conveying of water, for pumps, water-engines, &c. are usually of lead, iron, earth, or wood; the latter are usually made of oak or elder. Those of iron are cast in forges : *their usual length is from six to eight feet; several of these are commonly fastened together by means of four screws at each end, with leather or old hat between them, to stop the water. Those of earth are made by the potters; these are fitted into one another, one end being always made wider than the other. : To join them the closer, and prevent their breaking, they are i covered with tow and pitch : their length is usually about that of the iron pipes. The wooden pipes are trees bored with large iron augurs of different sizes, beginning with a less, and then proceeding with a larger, successively; the first being pointed, the rest being formed like spoons, increasing in diameter from one to six inches, or more; the pipes are fitted into the extre- mities of each other, as here represented, and are sold by the ©l-I H foot. Wooden pipes are bored, either by a borer advancing horizontally, while the wood to be pierced is turned round, in some such manner as in boring of ordnance; or, by causing the timber to be gradually advanced, while the borer turns round; the latter method is the most common. The apparatus most frequently adopted, when the first mover is a stream of water, is that invented by M. Morel. - This machinery, (see Plate Pile Engines, &c.) is represented at fig. 6, where the vertical wheel A is put into motion by water descending upon it through a trough or sloping canal: upon the horizontal axle of this wheel is a cog wheel B, which gives motion to the lanterns C, D, the common âxis of these lanterns being in a vertical position. The lantern D turns at the same time two cog wheels E and F; the first, E, which is vertical, turns the augur that bores the wood; and the second, F, which is horizontal, has attached to it by a pin which is at a small distance from its centre, a lever or arm H, with a hook at its end, taking into the indentations of one of the wheels of the carriage that carries the wood to be bored. Another lever, I, hanging upon the former, is prevented from falling by a spring, and pushes by its extremity against the notches of the lower end of the same wheel. Thus, as the cog wheel turns round, the carriage-wheel is first pulled forward by the hook and lever H, and then pushed backward as far by the arm I; by this means causing a pinion upon the axle of the carriage wheel to advance the rackwork above it, together with the timber to be bored ; so that the timber is advanced by a slight reciprocating motion of the carriage. The augur, being generally some feet in length, plays in holes in two pieces L., L, which retain it in its horizontal position, and thus it forms a cylindrical cavity in the wood, as required. PIPES, Tobacco, are made of various fashions; long, short, plain, worked, white, varnished, unvarnished, and cf various colours, &c. f - PIPRA, the IHanakin, a genus of birds of the order of seres. Latham describes 25 species, and five varieties. PIRACY, is the seizing or plundering a vessel on the high seas, without having a commission for that purpose. PIRATE, a sea robber. By stat. 28. Hen. VIII. c. 15. all treasons, felonies, robberies, murders, and confederacies, com- mitted upon the sea, or in any haven, creek, or place, where the . admiral has jurisdiction, shall be tried in such shires or places as the king shall appoint by his commission, in like forms as if such offence had been committed upon land, and according to the course of the common law, and the offenders shall suffer death, without benefit of clergy. And by stat. 6 Geo. I. made per- petual, it is enacted, that if any of his majesty’s natural born subjects, or denizens of this kingdom, shall commit any piracy or robbery, or any act of hostility, against other his majesty’s subjects upon the sea, under colour of any commission from any prince or state, or pretence of authority from any person whatsoever, such offender shall be deemed to be a pirate, felon, and robber; and being duly convicted thereof, according to this act, or the aforesaid act of 23 Hen. VIII. shall have and suffer such pains of death, loss of lands, goods, and chattels, as pirates, felons, and robbers upon the seas, ought to have and suffer. By 18 Geo. II. c. 30, persons committing hostilities, or aiding enemies at sea, may be tried as pirates. Piracies at sea are excepted out of the general pardon, by 20 Geo. II. c. 52. PIRA l'E's Goods go to the admiral by grant; but not piratical pas- goods, which go to the king, if the owner is not known. , P I S P I s 809 DICTIONARY OF MECHANICAL science. PISCES, the Fishes ×, are the last of the signs in the fixed zodiac, and consequently the last of the Southern and Winter signs: the sun enters it about the 19th of February, and the earth is then just entering into the sign Virgo. Reckoning, how- ever, by the visible zodiac, this sign has taken the place of Aries, and it is chiefly situated on the north side of the equator; the Fishes have therefore become the leaders of the celestial hosts; and on all artificial representations of the heavens, wherein the constellations are laid down according to their recession from the vernal equinox, as established by the intel- lectual zodiac of Hipparchus, the Sun actually enters Pisces about the 6th of March. - - , Pisces, Fishes, in Natural History, is the fourth class in the Linnaean system, consisting of five orders, viz. Abdominales, Apodes, Cartilaginii, Jugulares, and Thoracici. The class is described as having incumbent jaws; eggs without white; organs of sense ; for covering, imibricate scales; fins for sup- porters; they swim in water; respiration is performed by means of gills, which supply the place of lungs. Air is equally neces- sary to the existence of fish, as it is to other animals. This process, in fishes, as breathing in the human subject, is carried on during sleep, and is repeated about twenty-five times in a minute; and the necessity of it is evinced, from the circum- stance of fish being certainly killed in water, from which air is taken away by means of the air-pump, or excluded by very severe frost. Should the free play of the gills be even sus- pended, or their covers kept from moving, by a string tied round them, the fish would fall into convulsions, and die in a few minutes. It is said, likewise, that though the branchial apparatus be comprised in a small compass, its surface, when fully extended, would occupy many square feet; a fact, that may convince the most sceptical, of the numberless convolu- tions and ramifications in which the included water is elabo- rated and attenuated, in the course of giving out its air in the respiratory process. Fishes have the organs of sense, some of them probably in a very high degree, and others' imperfectly; of the latter-kind, are the senses, of touch and of taste; but the serise of hearing has now been completely ascertained, which was long doubted, and by some physiologists denied : the organ is contained in the cavity of the head. The organ of smelling is large, and the animals have a power of contracting and dilating the entry to it as they have occasion. It seems to be mostly by their acute smell that they discover their food, for their tongue seems not to have been designed for a very nice sensation, being of a pretty firm cartilaginous substance; and common experience evinces, that their sight is not of so much use to them as their smell in searching for their nourish- ment.—We now proceed to notice the motion of fishes, for the celerity of which their shape is admirably adapted ; hence, vessels designed to be navigated in water, are made to imitate, in some degree or other, the shape of fish ; but the rapidity of a ship in sailing before the wind, is not to be compared to the velocity of a fish. The largest fishes are known to overtake a ship in full sail with the greatest ease, to play round it without effort, and to surpass it at pleasure. Every part of the body seems formed for despatch : the fins, the tail, and the motion of the whole backbone, assist in the business; and it is to that flexibility of body which mocks the efforts of art, that fishes owe the great velocity of their motions. The chief instruments in a fish's motion are its fins, air-bladder, and tail; with two pair, and three single fins, it will migrate a thousand leagues in a season, and without indicating any visible symptoms of languor or fatigue. By means of the air bladder, fishes can increase or diminish the specific gravity of their body. When they contract it, and press out the air, the bulk of the body is diminished, and the fish sinks as far as it pleases: on relaxing the operation, the bladder acquires its natural size, the body hecomes specifically lighter, and the fish is enabled to swim near the surface. The tail, in the last place, may be regarded as the rudder, directing the motions of the fish, to which the fins are only subservient. With respect to the nourishment of fishes: they are mostly carnivorous, though they seize upon almost any thing that falls in their way; and not uncommonly devour their own offspring; they seem, indeed, to manifest a particular predilection for whatever they can swallow possessed of life. 83. far the greater number are produced from eggs. three to ten quarters. the Dwarf marrow : the Prussian blue. Fishes can, however, notwithstanding their natural yoracity, live long, apparently, without food; but they, perhaps, in vases and other ornamental vessels, feed on insects too small for the human eye to see; or, it has been thought, they may have the power of chemically decomposing water. A few species of fishes, as the eel, blenny, &c. are viviparous; but by w Fishes have different seasons for depositing their spawn. Some, which live in the depths of the ocean, are said to choose the winter months; but, in general, those with which we are acquainted, choose the hottest months in summer, and prefer such water as is somewhat tepified by the beams of the sun. They then leave the deepest parts of the ocean, which are the coldest, and shoal round the coasts, to swim up the fresh water rivers, which are warm as they are comparatively shallow, depositing their eggs where the sun's influence can most easily reach them, and seeming to take no farther charge of their future progeny. Of the eggs thus deposited, scarcely one in a hundred brings forth an animal, as they are devoured by all the lesser fry which frequent the shores, by aquatic birds near the margin, and by the larger fish in deep water. Still, however, the sea is amply supplied with inhabitants; and notwithstanding their own rapacity, and that of various tribes of fowls, the numbers that escape are sufficient to relieve the wants of a considerable portion of mankind. Indeed, when we consider the fecundity of a single fish, the amount will seem astonishing. If we should be told, for example, that a single being could in one season produce as many of its kind as there are inhabitants in Eng- land, it would strike us with surprise; yet the cod annually spawns, according to Lewenhoeck, above nine million of eggs contained in a single roe. The flounder is commonly known to produce above one million; and the mackarel above five hundred thousand; a herring of a moderate size, will yield at least ten thousand; a carp, of fourteen inches in length, con- tained, according to Petit, two hundred and sixty-two thousand two hundred and twenty-four; and another, sixteen inches long, contained three hundred and forty-two thousand one hundred and forty-four; a perch deposited three hundred and eighty thousand six hundred and forty; and a female sturgeon, seven million six. hundred and fifty-three thousand two hundred. The viviparous species are by no means so fruitful; yet the blenny brings forth two or three hundred at a time, all alive and playing round the parent together. - PISCIS AUSTRALIS, the Southern Fish, is one of the old constellations, the brilliant of which was a subject of great study by the Egyptians and Ethiopians, as I have already observed. The river of Aquarius is lost at the mouth of the Fish, as our astronomers depict the constellations. The brilliant Fomalhaut is nearly on the same meridian with Markab in Pegasus; but , Kircher's Planispheres are destitute of this symbol; yet we may conceive its high antiquity from the place it holds among the celestial host, and its relation with Aquarius. PISCIS VOLANS, the Flying Fish, situated on the Antarc- tic circle, contains eight stars all under the 4th magnitude. PISODIT, a mineral found at Carlsbad, in Bohemia. It has the form of round masses composed of concentric layers, and containing a grain of sand in their centre. Colour white, often grayish, reddish, or yellowish. - PISTOLE, a Spanish gold coin, of which there are quad- ruple, double, and half pistoles. - PISTON, in Mechanics, denotes a short cylinder working within another hollow cylinder, as in water or air pumps, and some other machines. g - PISUM SATI v UM. (The Pea.) The gray hog pea used to be the only one sufficiently hardy for culture in the fields; but since the improvement of our agriculture, we have all the finer varieties cultivated in large quantities. The seed used is about two bushels and a half per acre, and the produce varies from The varieties of peas are many, but the principal ones used in agriculture are the early Charlton pea; All these are dwarf kinds, and as the demand for this article in war time is great for the navy and army, if the farmer's land will suit, and pro- duce such as will boil, they will fetch a considerably greater price in proportion. The varieties that are found to boil are either used whole, or split, which is done by steeping them in water till the cotyledons swell, after which they are dried on a 9 U º * 810 P L 'A P L - A DICTIONARY OF MECHANICAL SCIENCE. kiln, and passed through a mill; the two cotyledons, fall apart. rº- which just breaking the hu sk, PITCH, a tenacious oily substance, drawn chiefly from pines and firs, and used in shipping, medicine, and other arts; or it is more properly tar, inspissated by boiling it over a slow fire. PITCH, Mineral, has a strong resemblance to common pitch. Colour black, dark brown, or reddish, Specific gravity from 1.45 to 2. Does not stain the fingers. - with a strong smell, and leaves a quantity of gray ashes. ... PITCHING, is the vertical vibration which the length of a On a white iron it flames : ship makes about her centre of gravity, or the moment by which she plunges her head and afterpart alternately into the hollow of . the sea. This motion may proceed from two causes; the waves which agitate the vessel, and the wind upon the sails which makes her stoop at every blast. g upon the agitation of the sea, and is not susceptible of inquiry; and the second is occasioned by the inclination of the masts, and may be submitted to certain established maxims. When the wind acts upon the sails, the masts yield to its effort with an inclination which increases in proportion to the length of the mast, to the augmentation of the wind, and to the comparative weight and distribution of the ship's lading. The repulsion of the water to the effort of gravity, opposes itself to this inclina- tion, or at least retains it by as much as the repulsion ºxºceds the momentum or absolute effort of the mast, upon which the The first absolutely depends. wind operates. At the end of each blast, when the wind sus- pends its action, this repulsion lifts the vessel; and these suc- cessive inclinations and repulsions produce the movement of pitching, which is very inconvenient; and when it is consider- able, will greatly retard the course as well as endanger the mast and strain the vessel. PITCHSTONE. This stone, which occurs in different parts of Germany, France, and other countries, has obtained its name from some resemblance which it has been supposed to have to pitch. It is most usually in amorphous pieces of different sizes. PITH, in Vegetation, the soft spongy substance contained in the central parts of plants and trees. - § PIVOT, a foot or shoe of iron, or other metal, usually coni- cal, or terminating in a point, by which a body, intended to turn round, bears on another fixed and at rest, and performs its revolutions. The pivot usually bears or turns round in a sole, or piece of iron or brass, hollowed out to receive it. . . PLACE, in Philosophy, that part of immoveable space which any body possesses or occupies, having to space the same relation that time has to duration. PLACE has various denominations, as absolute, relative, pri- mary, &c., which will be readily comprehended without any formal definitions. . * PLAGUE, in the time of Justinian the Emperor.—The follow- ing dismal relation of this dire calamity is given in the eloquent language of Mr. Gibbon.—Ethiopia and Egypt have been stig- matized in every age as the original source and seminary of the plague. In a damp, hot, stagnating air, this African fever is generated from the putrefaction of animal substances, and especially from the swarms of locusts, not less destructive to mankind in their death than in their lives. The fatal disease which depopulated the earth in the time of Justinian and his successors, first appeared in the neighbourhood of Pelusium, between the Serbonian bog and the eastern channel of the Nile. From thence, having as it were a double path, it spread to the east over Syria, Persia, and the Indies, and penetrated to the west, along the coast of Africa; and over the continent of Europe. In the spring of the second year, Constantinople, during three or four months, was visited by the pestilence; and Procopius, who observed its progress and symptoms with the eyes of a physician, has emulated the skill and diligence of Thucydides in the description of the plague of Athens. usual occupation, were surprised by a slight fever; so slight, indeed, that neither the pulse nor the colour of the patient gave any signs of the approaching danger. The same, the next, or the succeeding day, it was declared, by the swelling of the glands, particularly those of the groin, of the arm-pits, The infection was sometimes announced by the visions of a dis-, tempered fancy; and the victim despaired as soon as he had heard the menace and felt the stroke of an invisible spectre. But the greater number in their beds, in the streets, in their the most distant regions. and under the ear; and, when these buboes' or tumors were opened, they were found to contain a coal or black substance of the size of a lentil. If they came to a just swelling and sup- puration, the patient was saved by this kind and natural dis- | charge of the morbid humour. But, if they continued hard and dry, a mortification quickly ensued, and the fifth day was com- monly the term of his life. The fever was often accompanied by lethargy or delirium ; the bodies of the sick were covered with black pustules or carbuncles, the symptoms of immediate death; and, in the constitutions too feeble to produce an erup- tion, the vomiting of blood was followed by the mortification of the bowels. To pregnant women the plague was generally mortal. Youth was the most pernicious season, and the female sex was less susceptible than the male ; but every rank and profession was attacked with indiscriminate rage; and many of those who escaped were deprived of the use of their speech, without being secure from a return of the disorder. The phy- sicians of Constantinople were zealous and skilful, but their art was baffled by the various symptoms, and pertinacious vehemence of the disease: the same remedies were productive of contrary effects, and the event capriciously disappointed their prognostics of death or recovery. The order of funerals and right of sepulchres were confounded; those who were left without friends or servants lay unburied in the streets, or in their desolate houses; and a magistrate was authorized to collect the promiscuous heaps cf dead bodies, to transport them by land or water, and to inter them in deep pits beyond the precincts of the city. Their own danger, and the prospect of public distress, awakened some remorse in the minds of the most vicious of mankind; the confidence of health again revived their passions and habits. The plague had touched the person of Justinian himself. During his sickness, the public conster- nation was expressed in the habits of the citizens, and their idleness and despondency occasioned a general scarcity in the capital of the East. Contagion is the inseparable symptom of the plague, which, by mutual respiration, is transfused from the surfeited persons to the lungs and stomach of those who approach them. While philosophers believe and tremble, it is singular that the real danger should have been denied by a people most prone to vain and imaginary terrors (the French.) Yet, the fellow-citizens of Procopius were satisfied, by some short and partial experience, that the infection could not be gained by the closest conversation; and this persuasion might support the assiduity of friends and physicians in the care of the sick, whom inhuman prudence would have condemned to solitude and despair. But the fatal security, like the predesti- nation of the Turks, must have aided the progress of the con- tagion; and those salutary precautions, to which Europe is indebted for her safety, were unknown to the government of Justinian. No restraints were imposed on the free and fre- quent intercourse of the Roman provinces; from Persia to France the nations were mingled and infected by wars and emigrations; and the pestilential odour, which lurks for years in a bale of cotton, was imported, by the abuse of trade, into The mode of its propagation is explained by the remark of Procopius himself, that it always spread from the sea-coast to the inland-countries: the most sequestered islands and mountains were successively visited ; the places which had escaped the fury of its first passage, were alone exposed to the contagion of the ensuing year. The winds might diffuse that subtle venom ; but, unless the atmo- sphere be previously disposed for its reception, the plague would soon expire in the cold or temperate climates of the earth. Such was the universal corruption of the air, that the pestilence, which burst forth in the 15th year of Justinian, A.D. 542, was not checked or alleviated by any difference of the seasons. In time its first malignity was abated and dispersed; the disease alternately languished and revived; but it was not till the end of a calamitous period of fifty-two years that man- kind recovered their health, or the air resumed its pure and salubrious quality. No facts have been preserved to sustain an account, or even a conjecture, of the numbers” that perished in this extraordinary mortality. I only find that, during three * It is probable that no less than an hundred millions of human beings fell victims to this contagion in the Roman empire alone !!! - P L A P L A 811 DICTIONARY OF MECHANICAL SCIENCE. months, five, and, at length ten, thousand people died each day at Constantinople; that many cities of the East were left vacant; and that, in several districts in Italy, the harvest and the vintage withered on the ground. The triple scourge of war, pestilence, and famine, afflicted the subjects of Justinian; : and his reign is remarkable for a visible decrease of the human : species, which has never been repaired, in some of the fairest countries of the globe. . distilled from mint, rosemary, angelica roots, &c. PLAIN, in general, an appellation given to whatever is smooth and even, or simple, obvious, and easy to be under- stood; and consequently, stands opposed to rough, enriched, or laboured. A plain figure, in geometry, is an uniform surface, from every point of whose perimeter, right lines may be drawn to every other point in the same. A plain angle is one con- tained under the two lines or surfaces, in contradistinction to a solid angle. The doctrine of plain triangles, as those included under three right lines, is termed plain, trigonometry. PLAIN Number, is a number that, may be produced by the multiplication of two numbers, into one another; thus 20 is a plain number produced by the multiplication of 5 into 4. PLAIN, Place, locus planus, or locus ad planum, among the ancient geometricians, denoted a geometrical locus, when it was a right line, or a circle, in opposition to a solid place, which was an ellipsis, parabola, or hyperbola. , PLAIN Problem, in Mathematics, is such a problem as can- not be solved geometrically, but by the intersection either, of a right line and a circle, or of the circumferences of two ciréles ; as, given the greatest side, and the sum of the other two sides of: a right-angled triangle, to find the triangle, as also to describe a trapezium that shall make a given area of four given lines. PLAIN Table, in Surveying, a very simple instrument, whereby the draught of a field is taken on the spot, without any future protraction. - * PLAN, in general, denotes the representation of something drawn on a plane, such are maps, charts, ichnographies, &c. PLANE. See GeoMETRY. PLANE, is a term used by shipwrights, implying the area or imaginary surface contained within any particular outlines, as,the plane of elevation, the plane of projection, the horizontal plane. PLANE, in Joinery, an edged tool, or instrument, for paring and shaving of wood smooth. - PLANET, a wandering star, as distinguished from the fixed stars, which always preserve the same relative position with respect to each other. Hence it follows that comets and satel- lites are included, according to the original signification of this term, under the same general denomination; in fact, the early astronomers had no idea of comets being permanent bodies, and as they were also unacquainted with any satellite but the moon, which with the sun was supposed to revolve about the earth, it was natural for them to class both under the same ge- neral appellation. But modern astronomers, in order to make a distinction between these, define a planet to be a celestial body revolving about the sun as a centre, with a moderate degree of eccentricity; thus excluding comets, the eccentricity of whose orbits is very considerable, and the satellites, which revolve about their primaries as the primaries do about the Sun. These last are, however, sometimes called secondary planets. See Ast RonoMY. We have given, under the several articles EccENTRI city, DISTANCE, ORBIT, Period, &c. the several particulars included under those denominations, as also under the names of the several planets, the respective elements of cach; and we have therefore, in this place, only to state a few popular observations relative to the probable nature, motion, appearances, &c. of these celestial bodies; and to give a general view of the ele- ments and other particulars of the planetary system. then, all the planets perform their revolutions in elliptical orbits about the sun, which is situated in one of the foci of the ellipse ; the orbit of each planet lies in a plane, which passes through the centre of the sun; those which are nearest the centre move with a greater velocity than those that are more remote; the same planet is also quicker or slower according as it is in that part of its orbit which is nearer or more remote from the cen- tral body; and all their motions are performed in the same ord er PLAGUE Water, one of the compound waters of the shops, First, from west to east, or according to the order of the signs. The motions and distances of the several planets are related to each other by invariable laws, viz. that the cubes of their periodic times of revolution, are as the squares of their distances from the sun ; and that equal areas are described by the same planet in equal times; that is, if we suppose a line drawn from the sun to a planet, and to move about it as a centre, that line will pass over or describe equal areas in equal times; therefore since the periods of the planetary revolution are accurately known from observation, we may hence find the exact proportional distance of all these bodies. See Kepler's LAws. It has been discovered by means of spots, observable on the discs of the planets, that they have a rotatory motion about their own axes, the time of which, however, seems to follow no particular law either with regard to their magnitude or distance from the Sun. Hence it appears that these bodies have each a diversity of seasons, their spring, summer, autumn, and winter, resembling those in our planets; they have likewise the same alternations of day and night, and in short, that they are fitted to the accommodation of inhabitants. . gº “With constitutions ſitted to the spot Where Providence all-wise has fixed their lot.” The excessive heat and cold experienced in those regions, in consequence of their proximity or remoteness from the sun, as have been supposed and even computed by some authors, ap- pear to be wholly imaginary. Uranus, the most distant planet in our system, has a temperature perhaps not at all different from Mercury, who revolves much nearer to the sun than ourselves. The light and heat received and experienced in our globe, seems to depend more upon the constitution of the atmosphere than any other cause; or why have we mountains covered with per- petual snow, and whence that diminution of light and heat ex- perienced by aerial voyagers, but in consequence of the ex- treme rarity of the air in the upper regions? and if this be granted, it follows immediately that a simple modification in the atmospheres of the several planets, would render the tempe- rature of each supportable even by terrestrial inhabitants. The idea of the temperature of the several planets depending upon their distances from the sun, arises from considering that body, not simply as the cause of heat, but as an immense mass of fire, possessing in itself, independent of any other agent, the power of heat; whereas there is every reason to conclude that it is only by a combination of the solar rays with certain parts of our atmosphere that the effect is produced. Water poured upon unslacked lime generates heat in the combined mass, and if we could imagine a being existing in such a mass, we should have no difficulty in conceiving that he would attribute that quality to the water, which we attribute to the sun, although in this case the contrary is evident. We cannot doubt then, without presumptuously limiting the power and wisdom of the Deity, that each of these planets is peopled with millions of beings engaged like us in the anxious vicissitude of life, and probably each having its philosophers and astronomers con- templating this immense globe, as a mere speck in the starry firmament. Nor must we stop here; it is also highly probable that every fixed star is another centre, about which planets are revolving, as those of our system do about the sun, Instead therefore of one sun and one world, as the ignorant imagine, reason and contemplation point out to us millions, of suns and millions of worlds, each peopled by myriads of inhabitants, dis- persed through infinite spacé, to which our system appears but as a mere point or atom, and is almost lost in the immensity of the creation. - What an august, what an amazing conception, if human imagination can conceive it, does this give of the works of the Creator | Thousands of thousands of suns multi- plied without end, and ranged all round us, at immense dis- tances from each other, attended by ten thousand times ten thousand worlds, all in rapid motion, yet calm, regular, and harmonious, invariably keeping the paths prescribed them; and these worlds peopled with myriads of intelligent beings, formed for an endless progression in perfection and felicity. If so much power, goodness, and magnificence, be displayed in the material creation, which is the least considerable part of the universe, how great, wise, and good must HE be, who finade and governs the whole !” - 812 P L 'A P L A DICTIONARY OF MECHANICAL | SCIENCE. Elements of the PlaNets, are certain quantities which are which five relate to the elliptic motion, viz. 1. The duration of the sidereal revolution. 3. The eccentricity, from which is derived the greatest equation of the centre. 4. The mean longitude of the planet at any given orbit with the ecliptic. 2. The inclination of the orbit to this plane. - - variable angular motion, such as that of the radius vector of a planet in its orbit, may be exhibited. The common contrivance now in use for this purpose was invented, we think, by Desa- guliers; it consists of two elliptical wheels, connected either by teeth running into each other, or by a band; these wheels revolve on their foci, and while, the driving ellipses move uni- formly, the radius vector of the other has the required motion. A much older, and at the same time far better, method than that of Desaguliers, was the invention of M. Joli de Dijon, of which the following is an account. If it be desired to move a wheel of 24 teeth by a pinion of 6, in such a manner that in some parts of its revolution it shall move as swiftly as if it had but 12 teeth, and in other parts as slowly as if it had 48 teeth, the method of accomplishing this is as follows:— - 1. Describe the rectangle L M N 0, fig. 7, (see Plate Pile Engines, &c.) having its side NO equal to the radii of the great wheel, and the pinion taken together, and its breadth L. N equal to their thickness; which last must be greater, the more con- siderable the inequality of the proposed movement. Let N O be so divided in Q, that Q;O may be to Q N, as 6 to 48, that is to say, reciprocally as the velocity of the pinion to the greatest velocity of the wheel. Also divide LM in P, in the proportion of 6 to 12, or reciprocally, as the velocity of the pinion to the least velocity of the wheel. Then join PQ, and draw as many lines S R parallel to L. M., as there are intended to be teeth in 4. express, which are in the inverse ratio of their lengths. 2. ‘Let two truncated cones be: formed in the lathe; on | the great wheels; upon which writé the degrees of velocity they necessary to be known in order to determine the theory of their : , elliptic motion. Astronomers reckon seven of those quantities, of | equal to that which would be formed by the revolution of the 2. The mean distance or semi-axis major. trapezoid L. PQ N about L. N. as an axis; and the other equa. to what would be formed by the revolution of the trapezoid | PQ MO about the axis M. O. On the largest of these two epoch. 5. The longitude of the perihelion at the same epoch. The two other elements relate to the position of the orbit, and are, 1. The longitude at a given epoch of the nodes of the cones let the circles generated by the revolution of the points P, T, Q, be marked and distinguished by the same numeral figures as the corresponding parallels of the rectangle. L. O. Upon the two bases of the conic frustum describe radial lines, f . - which shall make angles at the centre, fig. 9, in the same pro- PLANet Wheels, are wheels by whose mutual connexion a portion to each other, as the intended velocities of the wheel, as expressed in fig. 8, and let teeth be cut in the curve surface | of the cone corresponding with these lines; after this, look on the circles that express the different velocities, and have been traced on the same surface, to find what part of each tooth. ought to remain opposite its corresponding radius, and cut or file the rest away. Thus will the teeth lie in an oblique or elliptical curve, on the conical surface, as is exhibited in the figure by a darker shade. The pinion must be made of a regu- lar conic shape, as is shewn at MO, in fig. 9. By this con- trivance, the largest or widest teeth will always meet the largest part of the pinion, and the narrowest will correspond with the smallest part; on which account, though the motion of the pinion be uniform, the wheel will be carried unequably, according to the assigned law; and in a similar manner may planet wheels be described to exhibit any other proposed variation. . . J , - . . . . . . PLANETARIUM, an astronomical machine, contrived. to represent the motions and various aspects of the heavenly bodies, parallelism of the earth’s axis, together with its diurnal motions, and by these means to explain the beautiful variety of the seasons, and other terrestrial and celestial phenomena, has ever been considered as one of the noblest efforts of me- chanical genius. Among the variety of machines contrived for these purposes, the Planetarium, or Portable Orrery, fig. 1, is best adapted for representing the celestial motions. # = T A planetarium may be considered, in short, as a diametrical section of the universe, in which the upper and lower hemis- pheres are suppressed. The upper plate is to answer for the ecliptic ; on this are placed, in two opposite but corresponding i Fig.1. with their respective characters; by this plate you may set the planetary balls so as to be in their respective places on the ecliptic for any day in the year. Through the centre of this plate you observe a very strong stem, on which is a brass ball to represent the Sun: round the stem are different sockets to carry the arms by which the several planets are supported. º - | or put on with ease, as occasion may require. circles, the days of the month, and the signs of the ecliptic, [. 5 y req | y tº | | N i | Smºnºſaurºra. [. #3 Sº dººr Krum nrº; U § §§ * * 37 º The planets are represented by ivory balls, having the hemi- sphere which is next the sun white, the other black, to exhibit their respective phases: and these planets may be taken off, - About the pri- mary planets are placed the secondary planets, or moons, which are, in some instruments, only moveable by the hand. By turn- ing the handle, all the planets are put in motion, moving round that ball which represents the sun. And, if we take the earth's Inotion as a standard, the other planets move with the same relative velocities and periodical times with which they traverse through space. The planetarium is furnished with a lamp, P L A P L A 813 DICTIONARY OF MECHANICAL SCIENCE which when it is placed into the socket on which the brass sun is fitted, throws the reflection of the sun's light upon all the planets, and gives their proper phases, &c. - In the Planetarium exhibited in the engraving, G) represents the Sun, which is fixed firmly to a wire a, and has no motion ; § is the planet Mercury, revolving round the Sun; ? is the planet Venus; GB represents the Earth, and ( the Moon revolving round it; f is a segment of brass called the Earth's terminator, which shews that all the parts of the Earth behind it are not illuminated by the Sun; 3 is the planet Mars; 2ſ. Jupiter and his four Satellites; P Saturn, with his ring and seven satellites; H Herschel, and six satellites. L is a small winch, which when turned gives motion to Mercury and Venus, and shews the Earth's annual motion round the Sun, its diurnal motion, and the Moon's motion round the Earth. The projection in the middle of the circular board M, consists of the following parts:—A steel wire A, whose lower end is screwed to a bridge under the board, and which carries the Sun; over this is put a tube, on whose lower end a worm wheel, worked by a worm on the arbour of the winch L above mentioned, is fixed; and to the upper end the frame of wheels N, with the Earth and Moon. Over these is a conical tube, which has a flaunch (at its lower end, and is fastened to the board M by three screws; the arms carrying the planets Mars, Jupiter, Saturn, and Herschel, are fitted stiffly upon this tube, so as not to turn, unless they are moved. These planets do not move by turning the winch, but are to be set by hand, as also their satellites. In the frame of wheels N, figs. I and 2, g is the first wheel, which is ſixed to the wire a, ſig. 1, and is with- out any motion; this works into another wheel h of the same size, fixed to the spindle i. The wheel h works another wheel k of the same size, on whose spindle y, fig. 1, the Earth is fixed. Besides the wheel h, the spindle i has three other wheels l mºn, fixed on it. The wheel l turns c, which works a pinion above the wheel g, carrying the planet Mercury in fig. 1: this pinion has a hollow spindle, and goes over the wire a. The wheel m on the spindle i works into p, which gives motion to the pinion g, (whose spindle goes over the spindle of the pinion which car- ries Mercury,) and has the planet Venus, in fig. 1, fixed to it. The large wheel n on the spindle i turns, by intermediate wheels, the pinion S, whose arbor goes over the spindle carry- ing the Earth: this has an arm for the Moon fixed to it. The wire t, to which the Moon is fixed, slides up and down through a hole in the end of the arm; and the lower end of the wire rests on a circular ring v, whose plane is parallel to the plane of the Moon's orbit, so that, as the arm turns round, the wire is pushed up by the inclination of the ring, and falls by its own weight. Beneath this is a ring, with divisions on it, shewing the Moon's age. worm wheel beneath the board M, and moves the frame N, fig. 1, with the Earth round the Sun; and as the wheel g is fixed, the wheel h is turned by rolling round it; and as k (which it works) is of the same size with the other two, it turns the |Earth, so that its axis always points to the pole. The wheel l, by means of the wheel o, turns the pinion, which carries Mercury in fig. 1. The wheel m, with the wheel p, turns g; and the planet Venus in fig. 1, and the wheel n, turns the pinion s, and the Moon, as before described. PLANETARY, something that relates to the planets. PLANETARY System, is the system or assemblage of the planets, primary and secondary, moving in their respective orbits, round their common centre the sun. PLANIMETRY, that part of geometry which considers lines and plane figures without any regard to heights or depths. Pla- nimetry is particularly restricted to the mensuration of planes and other surfaces: as contradistinguished from stereometry or the mensuration of solids, or capacities of length, breadth, and depth. PLANISPHERE, a projection of the sphere and its various circles on a plane ; as upon paper, or the like. In this sense, maps of the heavens and the earth, exhibiting the meridians and other circles of the sphere, may be called planispheres. PLANISPHERE is sometimes, also considered as an astrono- mical instrument, used in observing the motions of the hea- venly bodies; being a projection of the celestial sphere upon a plane representing the stars, constellations, &c. in their proper When the winch I, is turned, it works the situations, distances, &c. as the astrolabe, which is a common name for all such projections. In all planispheres the eye is supposed to be in a point, viewing all the circles of the sphere, and referring them to a plane beyond them, against which the sphere is as it were flattened; and this plane is called the plane of projection, which is always some one of the circles of the sphere itself, or parallel to some one of them. Among the infi- nite number of planispheres which may be furnished by the dif- ferent planes of projection and the different positions of the eye, there are two or three that have been preferred to the rest. Such as that of Ptolemy, where the plane of projection is paral- lel to the equator; that of Gemma Frisius, where the plane of projection is the colure, or solstitial meridian, and the eye of the pole of the meridian, being a stereographical projection ; or that of John de Royas, a Spaniard, whose plane of projection is a meridian, and the eye placed in the axis of that meridian at an infinite distance; being an orthographical projection, and called the anelemma. PLANKING, the act of covering and lining the sides of a ship with planks, which is sometimes by the artificers called laying on the skin. This completes the process of ship-building. PLANTAGO LAN.ceoLATA. (Rib Grass.) This is a peren- nial plant, and very usefully grown, either mixed with grasses, or sometimes alone: it will thrive in any soil, and particularly in rocky situations. It is much grown on the hills in Wales, where, by its roots spreading from stone to stone, it is often found to prevent the soil from being washed off, and has been known to keep a large district fertile, which would otherwise be only a bare rock. Sheep are particularly fond of it. About four pounds, sown with other seeds for pasture, will render a benefit in any situation that wants it. Twenty-four pounds is usually sown on an acre when intended for the sole crop, and Sown under corn. s PLANTING, in Agriculture and Gardening. The first thing in planting, is to prepare the ground before the trees or plants are taken out of the earth, that they may remain out of the ground as short a time as possible ; and the next is to take up the trees or plants in order to their being transplanted. In taking up the trees, carefully dig away the earth round the roots, so as to come at their several parts to cut them off; for if they are torn out of the ground without care, the roots will be broken and bruised, to the great injury of the trees. When you have taken them up, the next ſting is, to prepare them for planting, by pruning the roots and heads. And first, prune off all the bruised or broken roots, all such as are irregular and cross each other, and all downright roots, especially in fruit trees, shortch the larger roots in proportion to the age, the strength, and nature of the tree; observing, that the walnut, mulberry, and some other tender-rooted kinds, should not be pruned so close as the more hardy sorts of fruit and forest trees: in young fruit trees, such as pears, apples, plums, peaches, &c. that are one year old from the time of their bud- ding or grafting, the roots may be left only about eight or mine inches long; but in older trees, they must be left of a much greater length; but this is only to be understood of the larger roots, for the small ones must be chiefly cut quite out, or pruned very short. - - r The next thing is, the pruning of their heads, which must be differently performed in different trees, and the design of the trees must also be considered ; thus, if they are intended for walls or espaliers, it is best to plant them with the greatest part of their heads, which should remain on till they begin to shoot in the spring, when they must be cut down to five or six eyes, at the same time taking care not to disturb the roots. But if the trees are designed for standards, you should prune off all the small branches close to the place where they are produced, as also the irregular ones which cross each other; and after having displaced these branches, you should also cut off all such parts of branches as have, by any accident, been broken or wounded; but by no means cut off the main leading shoots, which are necessary to attract from the root, and thus promote the growth of the tree. - e Having thus prepared the trees, for planting, you must now proceed to place them in the earth; but if the first trees have been long out of the ground, so that the fibres of the roots are dried, place them eight or ten hours in water before they are 814 P. L. A P L A DICTIONARY OF MECHANICAL SCIENCE. planted, with their heads erect, and the roots only immersed in it, which will swell the dried vessels of the roots, and pre- pare them to imbibe nourishment from the earth. . In planting them, great regard should be had to the nature of the soil, for if that is cold and moist, the trees should be planted very shal- low, and if it is a hard rock or gravel, it will be better to raise a hill of earth where each tree is to be planted, than to dig into the rock or gravel, and fill it up with earth, as is too often prac- tised, by which means the trees are planted as in a tub, and have but little room to extend their roots. The next thing to be observed is, to place the trees in the hole in such a manner that the roots may be about the same depth in the ground as before they were taken up; then break the earth fine with a spade, and scatter it into the hole, so that it may fall in between every root, that there may be no hollow- ness in the earth. Having filled up the whole, gently tread down the earth with your feet, but do not make it too hard, which is a great fault, especially if the ground is strong or wet. Having thus planted the trees, they should be fastened to stakes driven into the ground, to prevent their being displaced by the wind, and some mulch laid about the surface of the ground about their roots: as to such as are planted against walls, their roots should be placed about a foot from the wall, to which the heads should be nailed, to prevent their being blown up by the wind. The seasons for planting are various, according to the different sorts of trees, or the soil in which they are planted; for the trees whose leaves fall off in winter, the best time is the beginning of October, provided the soil is dry; but if it is a very wet soil, it is better to defer it till the latter end of February, or the beginning of March; and for many kinds of evergreens, the beginning of April is by far the best season ; though they may be safely removed at Midsummer, provided they are not to be carried very far; but you should always make choice of a cloudy wet season. . . PLANTS, in Botany, organic vegetable bodies, consisting of roots and other parts. Increase of Plants or Vegetables.—The seeds of many kinds of vegetables are so numerous, that if the whole produce of a single plant were put into earth, and to come to maturity in due course, the Whole surface of the earth would be covered with them in a few years. Thus, the hyosciamus, which of all known plants, produces the greatest number of seeds, would for this purpose require no more than four years. According to some experiments, it has been found, that one stem of the hyosciamus produces more than 50,000 seeds, and if we admit the number to be only 10,000, it would amount, at the fourth crop, to 1,000,000,000,000,000; and as the whole surface of the earth is calculated to contain no more than 5,507,634,452, 576,256 square feet, it will be seen, that if we allow only a square foot to each plant, the whole surface of the earth would be insufficient to contain the produce of a single hyosciamus at the end of the fourth year. PLASTER, in Pharmacy, is defined to be an external appli- cation, of a harder consistence than our ointments; these are to be spread according to the different circumstances of the wound, place, or patient, either upon linen or leather. PLASTER, among Builders, &c. The plaster of Paris is a preparation of several species of gypsums, dug near Mont Maitre, a village in the neighbourhood of Paris; whence the Ika (Q (2. PLAT, a sort of plaited cordage formed of the yarns of old rope twisted into foxes. It is used to wind about that part of the cable which lies in the hawse-hole, where it would otherwise be greatly injured by the continual friction produced by the agitation of the ship in stormy weather. See the articles FRESHEN and Service. - PLATALEA, the Spoonbill, in Ornithology, a genus belong- ing to the order of grallae. The beak is plain, and dilates towards the point into an orbicular form; the feet have three toes, and are half-palmated. There are three species. * PLATANUS, the Plane Tree, a genus of the polyandria order, in the monoecia class of plants. There are two species, the Oriental and American. * PLATBAND of a Door or Window, is used for the lintel, where that is made square, or not much arched; these platbands are usually crossed with bars of iron when they have a great bearing, but it is much better to ease them by arches of dis- charge built over them. - - PLATE BACKSTAY, is a piece of iron used instead of a chain to confine the lower dead-eye of the backstay. Foot-hook, or Futtock PLATes, are iron bands fitted to the lower dead-eyes of the top-mast shrouds, which passing through holes in the edge of the top, are attached to the upper ends of the futtock-shrouds. - PLATFORM, is a number of planks laid together, forming a kind of floor for any temporary or particular purpose. PLATFoRM, in the Military art, an elevation of earth, on which cannon are placed, to fire on the enemy; such are the mounts in the middle of curtins Cºn the ramparts there is always a platform, where the cannon are mounted. It is made by the heaping up of earth on the rampart; or by an arrange- ment of madriers rising insensibly, for the cannon to roll on, either in a casement or an attack on the outworks. All prac- titioners are agreed that no shot can be depended on, unless the piece can be placed on a solid platform ; for if the platform shakes with the first impulse of the powder, the piece must likewise shake, which will alter its direction, and render the shot uncertain. - - - PLATFoRM, or Orlop, in a ship of war, a place on the lower deck, abaft the main-mast, between it and the cockpit, and round about the main capstan, where provision is made for the wounded men in time of action. . PLATINA, is one of the metals, for the discovery of which we are indebted to our contemporaries. Its ore has recently been found to contain likewise four new metals, palladium, iridium, osmium, and rhodium, (which see,) besides iron and chromium. Pure or refined platina is by much the heaviest body in nature. Its specific gravity is 21:54. It is very mal- leable, though considerably harder than either gold or silver; and it hardens much under the hammer. Its colour on the touchstone is not distinguishable from that of silver. Pure platina requires a very strong heat to melt it; but when urged by a white heat, its parts will adhere together by hammering. This property, which is distinguished by the name of welding, is peculiar to platina and iron, which resemble each other like- wise in their infusibility. Platina is not altered by exposure to air, neither is it acted upon by the most concentrated simple acids, even when boiling or distilled from it. The aqua regia best adapted to the solution of platina, is composed of one part of the nitric, and three of muriatic acid. The solution does not take place with rapidity. From its hardness, infusibility, and difficulty of bcing acted upon by most agents, platina is of great value for making various chemical vessels. Platina may be drawn into very fine wire. There are two oxides of platina. It is dissolved in chlorine, and sulphate of platina may be obtained by passing a current of sulphuretted hydrogen gas through the mitro-muriatic solution. A fulminating powder is obtained from platina. * PLATING, is the art of covering baser metals with a thin plate of silver, either for use or for ornament. . It is said to have been invented by a spur-maker, not for show, but for real utility. Till them the more elegant spurs in common use were made of solid silver; and from the flexibility of that metal, they were liable to be bent into inconvenient forms by the slightest accident. To remedy this defect, a workman at Bir- mingham contrived to make the branches of a pair of spurs hol- low, and to fill that hollow with a slender rod of steel iron. Finding this a great improvement, and being desirous to add cheapness to utility, he continued to make the hollow larger, and of course the iron thicker and thicker, till at last he dis- covered the means of coating an iron spur with silver in such a manner as to make it equally elegant with those which were made wholly of that metal. The invention was quickly applied to other purposes; and to numberless utensils, which were for- merly made of brass or iron, are now given the strength of these metals, and the elegance of silver, for a small additional expense. PLATONIC Year, or the Great Year, is the period of time determined by the revolution of the equinoxes, upon a suppo- sition of the precession going on uniformly till they have made one complete revolution. See PREcession. * PLATOON, in the Military art, a small square body of forty or fifty men, drawn out of a battalion of foot, and placed be- . P.A., ſº Zºº; // .3". P 8-1.5. - * * * * º º 2 *% | º º *@ Nº. | - - *Ligliº º º . \\ º | A \, º N N º N Q - Jºnazzº chazz, Aºozzº. ºils - = ~s i is- - - l º li-Hº - w - -- N * \ N A \\ º - ºf * - º - º Azazzº, Zizzzzurrºr Zºo”/. º º - º -º-Tº Tº … - º in - - \ \ ºr " ºm º __ - * - º - - º \ - \\ 2– - - - - ==º - *T - _- L ºr Ziwo - whee/ Zºo”. S. - - sº ºs- L y º º Published by Henry Fisher son & cºcarton London isº P L U P N E 815 DICTIONARY OF MECHANICAL SCIENCE. tween the squadrons of horse, to sustain them; or in ambus- cades, straits, and defiles, where there is no room for whole battalions or regiments. 4. PLATYPUS, a quadruped of the order, of bruta, but with a mouth shaped like the bill of a duck; feet webbed. * PLEA, that which either party alleges for himself in court. These are divided into pleas of the crown and common pleas. Pleas of the crown are all suits in the king's name against offences committed against his crown and dignity, or against his crown and peace. Common pleas are those that are held between common persons. Common pleas are either dilatory, or pleas to the action. Pleas dilatory, are such as tend merely to delay or put off the suit, by questioning the propriety of the remedy rather than by denying the injury. Pleas to the action, are such as dispute the very cause of suit. 3 Black. 301. PLEADINGS, in general, signify the allegations of par- ties to suits, when they are put into a proper and legal form; and are distinguished in respect to the parties who plead them, by the name of bars, replications, rejoinders, sur-rejoinders, rebutters, sur-rebutters, &c. and though the matter in the declaration of court does not properly come under the name of pleading, yet, being often comprehended in the extended sense of the word, it is generally considered under this head. PLEASURE BOAT, a boat fitted up for receiving company to sail up and down a river, harbour, or lake, &c. PLEIADES, in Astronomy, an assemblage of stars in the neck of the constellation Taurus. - PLENE ADMINISTRAVIT, a plea pleaded by an executor or administrator, where they have administered the deceased’s estate faithfully and justly before the action brought against them. . - º PLENUM, in Physics, denotes, according to the Cartesians, that state of things wherein every part of space is supposed to be full of matter; in opposition to a vacuum. . PLENUS FLos, in Botany, a full flower; a term expressive of the highest degree of luxuriance in ſlowers. The petals in full flowers are so multiplied as to exclude all the stamina, and frequently to choak up the female organ, so that such flowers, though delightful to the eye, are vegetable monsters. Flowers with more than one petal are most liable to this ; such as the ranunculus, anemony, poppy, myrtle, &c. &c. Flowers with one petal only are but seldom subject to this fulness; these, however, are not totally exempt, as may be seen in the double polyanthus, hyacinth, crocus, &c. In flowers with one petal, the mode of luxuriance, or impletion, is by a multiplication of the divisions of the limb, or upper part. In flowers with more than one petal, is a multiplication of the petals or nectarium. PLEURISY, in Medicine, a violent pain in the side, attend- ed with an acute fever, a cough, and a difficulty of breathing. PLEURONECTES, the Flounder, in Natural History, a genus of fishes of the order thoracici. Under this genus is in- cluded the Hallibut, the Plaise, the Dab, the Flounder, the Sole, the Turbot, &c. which require no particular description. PLOT, in dramatic Poetry, is sometimes used for the fable of a tragedy or comedy, but more particularly the knot or in- trigue which makes the embarrassment of any piece. The un- ravelling puts an end to the plot. - PLOT, in Surveying, the plot or draught of any field, farm, or manor, Surveyed with an instrument, and laid down in the proper figure and dimensions. -- PLOTTING, among Surveyors, is the art of laying down on paper, &c, the several angles and lines of a tract of ground surveyed by a theodolite, &c. and a chain. - PLOTUS, or DARTER, a genus of birds of the order anseres. The generic character is bill straight, pointed toothed ; nostrils a slit near the base ; face and chin naked; legs short, all the toes connected. Of this genus there are three species. PLOUGH, in Agriculture, a machine for turning up the soil, contrived to save the time, labour, and expense, that without || this instrument must have been employed in digging land to prepare it for the sowing of all kinds of grain. FLOUGH, among Bookbinders, is a machine for cutting the edges of the leaves of books smooth. PLUG, a piece of timber formed like the frustum of a cone, and is used for different purposes, as, Hawse-Plugs, are made to stop the hawse holes when the cables are unbent, mon with all other fluids. and therefore must also decrease in density. or not in them. Their use is to prevent the water coming in when the ship pitches. Shot PLUGs, are used to stop the breaches made in the bottom of a ship by cannon-balls, and are formed of various sizes, according to the different sizes of shot. * PLUMBERY, the art of casting and working lead, and using it in building. * PLUM-TR.E.E. See PRUNUS. - - PLUMMET, among Artificers, denotes a perpendicular to the horizon; so called as being commonly erected by means of a plummet. - PLUMMING, among Miners, is the method of using a mine- dial, in order to know the exact place of the work where to sink down an air-shaft, or to bring an adit to the work, or to know which way the load inclines when any flexure happens in it. PLUNDER, in sea language, a name given to the effects of the officers and crew of a prize, when pillaged by the captors. In the military art, plunder is a booty of any kind. PLUNGER, in Mechanics, the same with the forcer of a ump. * - * e p PLURALITY. If any person having one benefice with cure of souls of eight pounds a year in the king’s books, shall accept another of whatsoever value, and be instituted and inducted into the same, the former benefice shall be void; unless he has a dispensation from the archbishop of Canterbury, who has power to grant dispensations to chaplains of noblemen and others, under proper qualifications, to hold two livings, provided they are not more than thirty miles distant from each other, and provided that he resides in each for a reasonable time every year, and that he keeps a sufficient curate in that in which he does not ordinarily reside. PLUS in Algebra, a character marked thus +, used for the sign of addition. - . . DLUSH, in Commerce, a kind of stuff leaving a sort of velvet nap, or shag, on one side, composed regularly of a woof of a single woollen thread, and a double warp, the one wool, of two threads twisted, the other goat's or camel's hair; though there are some plushes entirely of worsted, and others composed wholly of hair. PLUVIOMETER, a machine for measuring the quantity of rain that falls. PLYING, in a nautical sense, is the act of making, or endeavouring to make, a progress against the direction of the wind, hence a good Plyer is a vessel that makes great advances in this manner of sailing. PNEUMATICS, may be defined the science which treats of the properties of air in general, or perhaps with more propriety the term expresses the science that investigates the mechanical properties of elastic and aeriform fluids, such as their weight, density, compressibility, and elasticity. In the article AIR PUMP, page 21, I have shewn how the weight, or specific gravity, of the air may be ascertained. The density, compressibility, and elasticity of the air were illustrated . in my explanation of the common air pump, its construction and principle of action, page 20 column 2. I shall in this article confine myself to experiments in pneu- matical science, as best calculated to illustrate its principles. Preliminary Facts.—The air is a fluid which we breathe; for it envelopes our globe to a considerable height around it. Clouds and vapours float in it, and the whole is called the at- mosphere. As it is possessed of gravity, like other fluids, it must press upon bodies in proportion to the depth at which they are immersed in it; and it also presses in every direction, in com- It however differs from all other fluids in the four following particulars:–1. It can be com- pressed into less space than it naturally possesses. 2. It can- not be congealed or fixed as other fluids may. 3. It is of a different density in every part upward from the earth's sur- face, decreasing in its weight, bulk for bulk, the higher it rises; 4. It is of an elastic or springy nature, the force of its spring being equal to its weight. - . . s People unacquainted with the principles of natural philoso- phy, would not suppose that the air by which we are sar- rounded, is a material substance, like other visible matter. Being invisible, and affording no resistance to the touch, it 816 P N E P N E DICTIONARY OF MECHANICAL SCIENCE. seems to them extraordinary, to consider it as a solid and material substance, yet a few experiments will convince them that it is really matter, possessing weight, and the power of resisting bodies that press against it. * Experiment 1.--Take a bladder that has not the neck tied, you may press the sides together and squeeze it into any shape. Blow into this bladder, and tie a string fast round the neck; you cannot then, without breaking the bladder, press the sides together; you can scarcely alter its figure by pressure. Whence then arise these effects? When empty, you could press the bladder into any form; but the air with which it is filled prevents this; the resistance you experience, when it is filled with air, proves that air is matter. Experiment 2–We say a vessel is empty, when we have poured out of it the water it contained: but if a glass jar be plunged with its mouth downward into a vessel of water, there will but very little water get into the jar, because the air, of which it is full, keeps the water out. Or, throw a bit of cork into a bason of water, put an empty tumbler over it with the mouth downwards, force it down through the water; the cork will shew the surface of the water within the tumbler, and you will see that it will not rise so high within as without the glass; nor, if you press ever so hard, will it rise to the same level. The water is, therefore, prevented from rising within the tum- bler, by some substance which occupies the inside. This sub- stance is air. - Exp. 3. Open a pair of common bellows, stop up the nozzle securely; you cannot shut the bellows, which seems filled with something that yields a little, like wool; unstop the nozzle, the air will be expelled, it may be felt against the hand, and the bellows will now shut.—When the air is at rest we can move in it with facility; nor does it offer a perceptible resistance, except the motion be quick, or the surface opposed to it consi- derable; but when this is the case, its resistance is very per- ceptible, as may be easily perceived by the motion of a fan. When air is in motion, it constitutes wind, which is nothing more than a current or stream of air, varying in its force ac- cording to its velocity. - - The invisibility of air, therefore, is only the consequence of its transparency; but it is possessed of all the common pro- perties of matter. We say a vessel is empty, in the usual way of speaking, when it is filled with air. - - The Mechanical Properties of Air.—But it is possible to empty a vessel of the air it contains, by which means we shall be able to discover several properties of this fluid. The instru- ment or machine by which this operation is performed, is called an AIR PUMP. See pages 20–23. - 4. To demonstrate the weight of air by experiment, take a hollow copper ball, or other vessel, which holds a quart, (wine measure), having a neck to screw on the plate of the air pump; weigh it when full of air, exhaust it, and weigh it when empty; it will have lost 16 grains, the weight of a quart of air. But a quart of water weighs 14624 grains : this divided by 16, quotes 914 in round numbers; so that water is 914 times as heavy as air, near the surface of the earth. - - When the receiver is placed upon the plate of the air pump without exhausting it, it may be removed again with the utmost facility, because there is a mass of air under it that resists, by its elasticity, the pressure on the outside ; but exhaust the re- ceiver, thus removing the counter pressure, and it it will be held down to the plate by the weight of the air upon it. 5. To determine what the pressure of the air amounts to. The surface of a fluid exposed to the air, is pressed by the weight of the atmosphere equally on every part, and remains at rest. If the pressure be removed from any particular part, the fluid yields in that part, and is forced out of its situation. Into the receiver A. put a small vessel with quicksilver, or any other fluid, and through the collar of leathers at B, suspend | a glass tube, hermetically sealed, over the small vessel. Ex- haust the receiver, let down the tube into the quicksilver, which will not rise into the tube as long as the receiver continues empty. Re-admit the air, the quicksilver will ascend. The reason is this ; upon exhausting the receiver, the tube is like- wise emptied of air; and therefore, when it is immersed in the quicksilver, and the air re-admitted into the receiver, the surface of the quicksilver is pressed upon by the air, except that portion which lies above the orifice of the tubc; consequently it must rise in the tube, and continue so to do, until the weight of the elevated quicksilver presses as forcibly on that portion which lies beneath the tube, as the weight of the air does on every other equal portion with the tube. Take a com- mon syringe of any kind, and having pushed the piston to the farthest end, immerse it into water; draw up the piston, the water will follow, because, when the pistonis pull- ed up, the air is drawn out of the syringe with it, and the pressure of the atmosphere is removed from the part of the water im- mediately under it ; consequently the water is obliged to yield in that part to the pres- sure on the surface. - 6. Upon this principle those pumps called, suching pumps act: the piston fitting tightly the inside of the barrel, by being raised up, removes the pressure of the atmosphere from that part, and consequently the water is drawn up by the pressure upon the surface. The pressure of the atmosphere is then the cause of the ascent of water in pumps; a column of water 33 feet high is a counterpoise to one as high as the atmosphere. As mercury is fourteen times as heavy as water, a column of that fluid need only be 1, of the length of one of water, to form an equal counterpoise to the pressure of the air ; and accord- ingly, having filled with mercury a glass tube about three feet long, hermetically sealed at one end, invert it into a small bason of mercury, and the mercury will rise to the height of about 29% inches, and there remain suspended, leaving at the top of the tube a space or perfect vacuum ; the column of mercury varies in height, and consequently the pressure of the air is differ- ent at different times. This phenomenon, too remarkable to be long unobserved, led to the observation that the changes in the height of the mercury were accompanied, or very quickly succeeded, by alterations in the weather. The instrument ob- tained the name of the weather glass: from its also mea- suring the weight of the atmosphere, it is called the Barometer, which is merely a tube filled with mercury, and inverted into a bason of the same. See BAROMETER, p. 91. 7. Take a receiver, open at the top, and cover it with your hand; exhaust the receiver, and thereby take off the pressure from the palm of the hand.: you will then feel it pressed down by immense weight, so as to give pain that would soon be insup- portable, and endanger the fracture of your hand. 8. If the top of the receiver be covered by a piece of flat glass, upon exhausting it, the glass will be broken to pieces by the incumbent weight; and this would happen to the receiver itself, but for its arched top, that resists the weight better than a flat surface. This experiment may be varied, by tying a a piece of wet bladder over the open mouth of the receiver, and leaving it to dry until it becomes as tight as a drum. Upon exhausting the receiver, you will perceive the bladder rendered concave, and it will yield more and more, until it break with a loud report occasioned by the air striking forcibly against the inside of the receiver. 9. Air, one of the most elastic bodies in nature, is easily com- pressed into less compass than it commonly occupies; and when the pressure is removed, it regains its former bulk. TA Let mercury be poured into a bent tube, A B | CD, open at both ends, to a small height, as BC | then stopping the end D with a cork or other- | wise air-tight, measure the length of confined air DC, and pour mercury into the other leg A B, till the height above the surface of that in CD be equal to the height at which it stands in the barometer at the time. Then it is plain, that the air in the shorter leg will be compress- ed with a force twice as great as at first, when it possessed the whole space C D ; for then it was compressed only with the weight of the atmosphere, but now it is compressed by that weight, and the additional equal weight of a º column of mercury. The surface of the mer- cury will now be at E; and it will be found. | | tºff º º P N E P N E DICTIONARY OF MECHANICAL SCIENCE. 817 upon measuring it, that the space D E, into which the air is now compressed, is just half the former CD. If another column of mercury were added, equal to the former, it would be reduced into one-third of the space it formerly occupied. Hence the density of the air is proportional to the force that compresses it. As all the parts of the atmosphere gravitate, or press upon each other, the air next the surface of the earth is more com- pressed and denser than what is at some height above it, in the same manner as wool thrown into a pit. bottom having all the weight of what was above it, would be squeezed into a less compass; the layer or stratum above it, would not be pressed so much ; the one above that, still less; and so on, till the upper one, having no weight over it, would be in its natural state. This is the case with the air, or atmo- sphere that surrounds our earth, and accompanies it in its mo- tion round the sun. On the top of lofty buildings, but still more on those of mountains, the air is less dense than at the level of the sea. The height of the atmosphere has never yet been ex- actly ascertained; on account of its elasticity, it may extend to an immense distance, becoming rarer in proportion to its distance from the earth. It is observed, that at a greater height than 45 miles, it does not refract the rays of light from the sun; and this is usually considered as the limit of the atmosphere. In a rarer state it may extend much farther, and this is by some thought to be the case, from the appearance of certain meteors which have been reckoned to be 70 or 80 miles distant, and whose light is thought to depend upon their coming through our atmosphere. A cubic inch of such air as we breathe, would be so much rarefied at the altitude of 500 miles, that it would fill a sphere equal in diameter to the orbit of Saturn. 10. There is a contrivance for supporting a guinea and a feather, and letting them drop at the same instant. If let fall while the receiver is full of air, the guinea will fall quicker than the feather; but if the receiver be exhausted, they both arrive at the bottom at the same instant, which proves that all bodies would fall to the ground with the same velocity, if it were not for the resistance of the air, which impedes most the motion of those that have the least momentum or weight. In this expe- riment, the observers ought to look at the bottom of the receiver, otherwise they will not be able to see whether the guinea and feather fall at the same instant. - 11. Take a receiver, having a brass cap fitted to the top with a hole in it; fit one end of a dry hazel branch about an inch long, tight into the hole, and the other end tight into a hole quite through the bottom of a small wooden cup ; pour quick- silver into the cup, exhaust the receiver, and the pressure of the outward air on the surface of the quicksilver will force it through the pores of the hazel, whence it will descend in a beautiful shower into a glass cup placed under the receiver to catch it. 12. Put a wire through the collar of leathers on the top of the receiver, and fix a bit of dry wood on the end of the wire within the receiver; exhaust the air, push the wire down so as to immerse the wood in a jar of quicksilver on the pump-plate; this done, let in the air, and upon taking the wood out of the jar and splitting it, its pores will be found full of quicksilver, which the force of the air drove into the wood. 13. Set a square phial upon the pump-plate, and having co- vered it with a wire cage, put a close receiver over it, exhaust the air out of the receiver; in doing which, the air will also make its way out of the phial, through a small valve in its neck —when the air is exhausted, turn the cock below the plate to readmit the air into the receiver: and as it cannot get into the phial again, because of the valve, the phial will be broken into pieces by the pressure of the air upon it. Had the phial been round, it would have sustained this pressure like an arch. 14. To shew the elasticity of air; tie up a very small quan- tity in a bladder, put it under the receiver; exhaust the air, the bladder (having nothing to act against it) will expand by the force of the air within it; upon letting the air into the receiver again, it will overpower that in the bladder, and press its sides close together. If the bladder so tied be put into a wooden box, and have 20 or 30 pounds weight of lead placed upon it, and the box be co- wered with a close receiver; upon exhausting the air out of the 84. The wool at the receiver, that confined in the bladder will expand and raise up the lead by the force of its spring. - 15. If a rat, mouse, or bird, be put under a receiver, and the air be exhausted, the animal will be at first oppressed as with a great weight, then grow convulsed, and at last expire in ago- nies. This experiment is too shocking to be practised, and we therefore substitute a machine called the lungs-glass, in place of the animal. - If a butterfly be suspended in a receiver, by a fine thread tied to one of its horns, it will fly about in the receiver as long as it continues full of air; but if the air be exhausted, though the animal will not die, and will continue to flutter its wings, it cannot remove itself from the place where it hangs, in the mid- dle of the receiver, until the air be let in again, and then the animal will fly about as before. 16. Put a cork into a square phial, and fix it in with wax or cement; and put the phial on the pump plate with the wire cage, and cover it with a close receiver; then exhaust the air out of the receiver, and the air that was corked up in the phial will break it outwards by the force of its spring, because there it no air left on the outside of the ſphial to act against that within it. -- 17. Put a shrivelled apple under a close receiver, exhaust the air, the spring of the air within the apple will plump it out, and cause the wrinkles to disappear: but upon letting the air into the receiver again, to press upon the apple, it will return to its former shrivelled state. Take a fresh egg, cut off a little of the shell and film from its smaller end, put the egg under a receiver, and pump out the air; all the contents of the egg will be forced into the receiver, by the expansion of a small bubble of air contained in the greater end between the shell and the film. - 18. Put some warm beer into a glass, set it on the pump, cover it with a close receiver, and then exhaust the air; the air therein will expand itself, and rise up in innumerable bubbles to the surface of the beer; and thence it will be taken away with the other air in the receiver. When the receiver is nearly ex- hausted, the air in the beer, which could not disentangle itself quick enough to get off with the rest, will now expand itself so as to cause the beer to have all the appearance of boiling; and the greatest part of it will go over the glass. 19. Put some water into a glass, and a bit of dry wainscot or other wood into the water; cover the glass with a close receiver, and exhaust the air; the air in the wood having liberty to ex- pand itself, will come out plentifully, and make the water to bubble about the wood, especially about the ends, as the pores lie lengthwise. A cubic inch of dry wainscot has so much air in it, that it will continue bubbling for nearly half an hour toge- ther. 20. Let a piece of cork be suspended by a thread at one end of a balance, and counterpoised by a leaden weight, suspended in the same manner, at the other. Let this balance be hung to the inside of the top of a large receiver; set it on the pump, and exhaust the air, the cork will preponderate, and shew itself to be heavier than the lead ; let in the air again, the equilibrium will be restored. The reason is, since the air is a fluid, and all bodies lose as much of their absolute weight in it as is equal to the weight of their bulk of the fluid, the cork being the larger body, loses more of its real weight than the lead; and therefore must be heavier, to balance it under the disadvantage of losing some of its weight. This disadvantage being taken off by remov- ing the air, the bodies gravitate according to their real quanti- ties of matter, and the cork which balanced the lead in air, shews itself to be heavier when in vacuo. 21. Set a lighted candle upon the pump, cover it with a tall receiver. If the receiver hold a gallon of air, the candle will burn a minute; and having gradually decayed from the first instant, it will go out; which shews that a constant supply of fresh air is as necessary to feed flame as to support animal life. The mo- ment the candle goes out, the smoke will ascend to the top of the receiver, and form a cloud; upon exhausting the air, the smoke will fall down to the bottom of the receiver, and leave it clear at the top. This shews that smoke does not ascend on account of its being positively light, but because it is lighter than air; and its falling to the bottom when the air is taken away, shews that it is not destitute of weight. So most sorts 9 Y 818 ſp O E P O A. " DICTIONARY OF MECHANICAL science. § of wood ascend or swim in water; and yet there are none who doubt of the wood's having gravity or weight. , rº 22. Set a receiver, open at top, on the air-pump, cover it with a brass plate and wet leather; having exhausted it of air, let the air in again at top through an iron pipe, making it pass through a charcoal flame at the end of the pipe; when the re- ceiver is full of that air, lift up the cover, and let down a mouse or bird into the receiver; the burnt air will, immediately kill it. If a candle be let down into that air, it will go out directly ; but by letting it down gently, it will drive out the impure air and good air will get in. * - 23. Set a bell on the pump-plate, having a contrivance so as to 1ing it at pleasure, and cover it with a receiver; then make the clapper strike against the bell, and the sound will be very well heard; exhaust the receiver of air, if the clapper be made to strike ever so hard against the bell, it will make no sound: this shews that air is absolutely necessary for the propagation of sound. Of condensed Air.—We now proceed to shew that the air can be condensed, or pressed into less space than what it gene- rally occupies, by an instrument called a condenser; see page 23 for an engraving of the machine. It consists of a brass bar- rel containing a piston, which has a valve opening downwards: } characterized by metrical harmony, and is by its very nature as the piston is raised, the air passes through the valve ; as the piston is pushed down, the air cannot return, and is therefore forced through a valve at the bottom of the barrel, that allows it to pass into the receiver, but prevents it returning. At every stroke of the piston, more air is thrown into the receiver, which is of very thick and strong glass. The receiver is held down upon the plate by a bar, firmly screwed to two upright props, and the air is let out of the receiver by a cock. A great variety of experiments may be performed by means of condensed air. Thus the sound of a bell is much louder in condensed than in common air; and a phial that would bear the pressure of the common atmosphere, when the air is exhausted from the inside, will be broken by condensing the air around it. - The Air Gun-This pneumatic instrument will drive a bulle with great violence by means of condensed air, forced into an iron ball by a condenser; but if the ball be not very good, it is apt to burst, and injure the operator. In 1820 a man was killed in Yorkshire by the bursting of the air-ball of an air gun. There are many contrivances used in constructing air-guns; some have a small barrel contained within a large one ; and the space between the two barrels serves for the reception of condensed air. The magazine air-gun differs from the common one only by having a serpentine barrel which contains ten or twelve balls: these are brought into the shooting barrel successively, by means of a lever; and they may be discharged so fast as to be nearly of the same use as so many different guns: see AIR GUN, page 23. - - * POA, ANNUA. general plant in all nature, grows in every situation where there is vegetation. It has been spoken of as good in cultiva- tion, and has had the term Suffolk grass applied to it, from its having grown in that county. - * - • PoA Aquatica, (Water Meadow-Grass,) is quite an iguatic, but is eaten when young by cattle, and is very useful in fenny countries: it is highly ornamental, and might be introduced into ponds for the same purpose as Arundo phragmites: it might also be planted with Festuca elation and Phalaris arundi- nacea, in wet dug-out places, where it would be useful as fodder, and form excellent shelter för game. - * * * - PoA Fluitans, (Flote Fescue-Grass,) would be, of all others, the most nutritive and best plant for feeding cattle; but it thrives only in water. It is highly recommended by the editor of Curtis's Observations on British Grasses, 5th edition. Cat- tle are very fond of it; but it is not to be cultivated, except in ponds, being perfectly aquatic. Linnaeus speaks of the seeds being collected, and sold in Poland and Germany as a dainty for culinary purposes; but it is never seen used here, neither are the seeds to be collected in great quantities. Stillingfleet speake highly of its merits in a water meadow, and also quotes Ray's account of the famous meadow at Orchiston, near Salis-. bury. . There this, as well as Poa trivialis, most certainly is in its highest perfection; but the real and general value of grasses, or other plants, must not be estimated by local instances. (Aunual Meadow-Grass.) This, the most . their order and arrangement. the stanza, it assumes a different character. composition. PoA Pratensis, (Smoothed-stalked Meadow-Grass,) is also a grass of considerable merit, when it suits the soil; it'affects a dry situation, and in some such places it is the principal herbage.” PoA Trivialis. (Rough-stalked Meadow-Grass.) Those who have observed this grass in our best watered meadows, and in other low pasture lands, have naturally been struck with its great produce and fine herbage. In some such places, it un- doubtedly appears to have every good quality that a plant of this nature can possess; it is a principal grass in the famous Orchiston meadow, near Salisbury; but persons should not be altogether caught by such appearances; for it is in some lands, and such as would produce good red clover, a very diminutive and insignificant plant indeed. When persons wish to intro- duce it, they should carefully examine their neighbouring pas- tures, and see how it thrives in such places. The seeds are small, and six pounds would be sufficient for an acre, with others that affect a similar soil. r - - POCKET, in the woollen trade, a word used to denote a larger sort of bag, in which wool is packed up to be sent from one part of thc kingdom to another. The pocket contains usually twenty-five hundred weight of wool. - POEMI. See POETRY. . - - . POETRY, is that kind of literary composition which is incapable of accurate definition. In the English language, versification depends on the modulation of the accents and the disposition of the pauses, to which is generally added the recurrence of rhyme. The heroic verse consists of ten syllables; its harmony is produced by a certain proportionate distribution of accented and unaccented syllables; and its specific charac- ter, whether lively or solemn, soft or slow, is determined by When unaccented and accent- ed syllables are regularly alternated, it is called the iambic Verse ; as, . “A shepherd's boy, he seeks no highler name, Led forth his flockſ besideſ the silver Thame.” * * When this order is inverted, and the unaccented is preceded by the accented syllable, it is called a trochaic verse; as, g 1 f “Ambition first sprung from the blest abodes.” “ Take, hºly earth, all that my soil holds dear.” The heroic verse is often diversified by the intervention of an Alexandrine line of twelve syllables, which is liberally used by Dryden: its abuse is pointedly censured by Pope: “A needless Alexandrine ends the song, Which, like a wounded snake, drags its slow length along.” It forms a noble termination : “Teach me to love and to forgive ; Exact my own defects to scan, What others are to feel, and know myself a man.” The common anapestic verse, of eleven and twelve syllables, in which the accent falls on every third syllable, has generally been appropriated to humorous subjects: when formed into In the noble war- song of Burns, it is however a strain truly sublime ; and in the following passage flows with equal sweetness and pathos: “”Tis night, and the landscape is lovely no more : I mourn, but, ye woodlands, I mourn not for you ; y For morn is approaching, your charms to restore, Perfum’d with fresh fragrance, and glittering with dew. Nor yet for the ravage of winter I mourn; Kind Nature the embryo blossom will save : But when shall spring visit the monldering urn? Oh! when shall it dawn on the night of the grave?”. The occurrence of double rhymes is neither very frequent nor very easy in English verse; they are chiefly employed in songs, and are seldom admitted in the higher order of lyrical The following passage from Dryden's Ode on St. Cecilia’s Day, affords the most happy example of this kind of verse in our language: - . “Softly sweet in Lydian measures, • 3 Soon he sooth'd his soul to pleasures ; War, he sung; is toil and trouble, Honour but an empty bubble; P O Fl P O I 819 DICTIONARY OF MECHANIAAL scIENCE. * Never ending, still beginning, Fighting still, and still destroying: If the world be worth thy winning, • . Think, Oh! think it worth enjoying.” - - Blank verse is composed of lines of ten syllables each, which flow into each other without the intervention of rhymes; its metrical principles reside in its pauses, which should be so judiciously spread as never to suffer the accompaniment of rhyme to be missed. Attempts have been made to enlarge the limits of blank verse, by the introduction of various measures analogous to those employed in rhyme: , but to all these efforts the genius of the language discovers an invincible repugnance ; vainly are varieties presented to the eye, which are impercep- tible to the mind, and untasted by the ear. All rhymeless numbers either flow into good blank verse, or form lines harsh and intractable ; a succession of abrupt sounds and mutilated sentences, which by no art of typography, by no imposition of nomenclature, can be made to constitute any metre at all. Poetical Classification.—Pastoral poetry is, above all other, the most limited in its object; and when formed on the model presented to us by Virgil and Theocritus, should be a descrip- tion of rural scenes and natural feelings, enriched with elegant language, and adorned by the most melodious numbers. The ballad is perhaps the happiest vehicle of pastoral poetry, and there are in our language many ballads of exquisite beauty. The name of Elegy, originally given to funeral monody, was afterwards attached to all plaintive strains. In the Greek and Latin languages it was always written in alternate hexameter and pentameter verse. By the moderns an elegiac stanza was invented, assimilating as nearly as possible with those 'slow melodious numbers. Many elegies, and perhaps the best, are expressive only of soothing tenderness. Such are those of Tyrtaeus and Alcaeus, imitated by Tibullus among the Ro- mans, and so happily by our countryman Hammond. The Jesse of Shenstone, which has perhaps never been surpassed, The celebrated elegy of Gray combines every is all pathos. charm of description and sentiment. The elegiac stanza, the monotony of which soon becomes oppressive to the ear, is sometimes happily exchanged for a lighter measure, as in Cowper's Juan Fernandez: . - “Ye winds that have made me your sport, Convey to this desolate shore Some cordial endearing report Of a land I shall visit no more. \ My friends do they now and then send A wish or a thought after me? Oh! tell me I yet have a friend, Though a friend I am never to seen.” 'The Sonnet represents in an abridged form the ancient elegy, or the same slow stanza is assigned to each, and the senti- ments suitable to the one are appropriate to the other. It is always limited to fourteen lines, an artificial character, which should seems to indicate an Oriental extraction. Lyric poetry is versatile and miscellaneous, admitting almost every diversity of measure and of subject. devotional sentiment, the triumphs of beauty and the praises of patriotism, are all appropriate to lyrical composition. The soul of enthusiasm, the spirit of philosophy, the voice of sym- pathy, may all breathe in the same ode. Of our lyrical writers, Dryden is confessedly eminent; Gray is distinguished by the majesty and delicacy of his expression and the correctness of his style; Collins is occasionally animated by a portion of Pindaric spirit. But perhaps there has not appeared in our language a more chaste and pleasing lyric poet than the pre- sent professor Smyth, of Cambridge, whose English lyrics breathe throughout all the chaste and soothing strains of genuine poetic enthusiasm. Didactic poetry is minutely pre- ceptive, and professes to convey useful instruction on some particular subject. It is obviously not easy to discover situ- ations in which an author may become a practical teacher, without ceasing to be the poet: and this difficulty is aggra- wated to the English writer, who has not the resources of the Greek and Roman in the metrical capacities of his language. Satirical poetry is descriptive of men and manners; its aim is to delineate the follies and chastise the vices of the age, Satire is evidently the offspring of polished times; and, unlike other Love and heroism, friendship and poets, the satirist finds his empire enlarged, and his influence extended, by the progress of society. Satire is either pointed or oblique; eloquence is the soul of the one, ridicule of the other. The one rushes on its object in a torrent of vehemence and declamation; the other pursues a smooth tortuous course, occasionally reflecting to the mind the most momentous truths in the playful aspect of wit and humour. Epic poetry concen- trates all that is sublime in action, description, or sentiment. In the structure of a regular epic poem, criticism requires that the fable should be founded in fact, and that fiction should fill the picture of which the outline is traced by truth. In the con- duct of the poem, it is exacted that the machinery be subser- vient to the main design, and that the action should be simple and uniform. There are, however, many poems of the epic or heroic cast, to which criticisin has hitherto assigned no name. It is obvious that the pbctical nomenclature established on classical authority, is not sufficiently extensive to include all the compositions of modern times. To what classical school shall we refer the noble ethics of Pope in his Epistles, and of Cowper in his Task 2 By what name shall we designate the Traveller and the Deserted Village, the Pleasures of Memory, the Pleasures of Hope, neither of which is like the Pleasures of Imagination included in the didactic species, with many other exquisite productions. Originally the drama was a me- trical composition, and exhibited all the critical refinements of poetry. The title of poet is still given to every dramatic author, although he should have written in prose, and although the highest dramatic powers may exist without the smallest talent for poetry. The avowed object of the drama is to develop the passions, or to delineate the manners of mankind: tragedy effects the one, and comedy the other. In the English language are many popular dramas of a mixed character, which are written in verse intermingled with prose, and which are called plays. The English drama deviates essentially from that of classical antiquity; and independent of the division of acts and scenes, there is little resemblance between them. The curiosa felicitas, that charm or felicity of expression which Horace so happily exemplified, is one of the most power- ful agents in producing poetical emotion. It is the attribute which belongs only to the poet of nature; and is the effusion of some fortunate moments, when consummate judgment has been impelled and inspired by exquisite feeling. The spirit of poetry is not confined to subjects of dignity and importance ; it may be perceived in a simple lay, and even in a sportive song. It visited Sappho, as it had sojourned with Pindar; and was as truly the attendant of Theocritus as of Homer. Nor is poetical emotion inspired only by the song of heroes and of gods; it may be awakened even by the strain of playful tenderness, in which the lover celebrates some darling of his mistress. See BLAIR's Lectures, CAMPBELL’s Philosophy of Rhetoric, KAIMes's Elements of Criticism. S POINT, in Geometry, as defined by Euclid, is a quantity which has no parts, or which is indivisible. Points are the ends or extremities of lines. If a point is supposed to be moved any way, it will, by its motion, describe a line. Poſ NT, is also an iron or steel instrument, used with some variety in several arts. Engravers, etchers, cutters in wood, &c. use points to trace their designs on the copper, wood, stone, &c. * - Point, in the Manufactories, is a general term used for all kinds of laces wrought with the needle ; such are the point de Venice, point de France, point de Genoa, &c. which are distin- guished by the particular economy and arrangement of their oints. p Poi Nt, among Sailors, a low arm of the shore which pro- jects into the sea, or into a river, beyond the contiguous part of . the beach. To Point a Gun, to direct it towards any particular object or point. To Point a Sail, to affix points through the eyelet holes of the reefs. See Points. Point Blank, in Gunnery, denotes the shot of a gun levelled horizontally. POINTING, in Naval affairs, is the operation of tapering the end of a rope, and weaving some of its yarns into a kind of mat about the diminished part of it, so as to thrust it more easily through any hole, and prevent it from being untwisted. Thus the end of a reef-line is pointed so, that being stiffer, it $28) P O ‘I 'P o L DICTIONARY OF MECHANICAL SCIENCE. may more readily penetrate the eyelet holes of the reef; and the ends of the strands of a cable are occasionally pointed for the greater conveniency of splicing it to another cable, especially when this task is frequently performed. The extremities of the splice of a cable are also pointed, that it may pass with more facility through the hawse-holes. In ships of war, it is customary to point the ends of almost all the ropes. POINTS, in Naval affairs, flat pieces of braided cordage, tapering from the middle towards each end, whose lengths are nearly double the circumference of the yard, and used to reef the courses and top-sails of a square-rigged vessel; they are fixed to the sails by passing one through every eyelet hole in the reef-bands, and making two knots upon it, one on each side of the sail, to prevent its falling out. See REEF. Points of the ComPAss, are the 32 principal points into which the horizon and compass-card are divided. See CoMPAss. Points, in Heraldry, are the several different parts of an es- cutcheon, denoting the local positions of any figure. POISONS, substances which, when applied to living bodies, tend to derange the vital functions and produce death. Some poisons act by their corrosive property, as arsenic and cor- rossive sublimate ; other poisons by being most powerfully as- tringent; some poisons are acrid, others narcotic and stupefy- ing, which probably have a direct power upon the brain; some destroy animal life by their putrescent qualities. - Poisons, witH THEIR syMPtoms AND ANTIDotes. Substances. Concentrated acids: the vitriolic, nitric, muri- atic, oxalic, &c.—Symptoms. Burning pain, vomiting. Matter thrown up effervesces with chalk, or salt of tartar, or lime, or magnesia.--Antidotes. Calcined magnesia: one ounce to a pint of warm or cold water. A glass full to be taken every two minutes, so as to excite vomiting. Soap, or chalk and water; mucilaginous drinks afterwards, such as linseed-tea, or gum arabic and water. * Substances. Alkalies: soda, ammonia, lime, &c.—Symptoms. Nearly the same as above: the ejected matter does not effer- yesce with alkalis, but with acids.--Antidotes. Vinegar and Hemon juice: a spoonful or two in a glass of water wery fre- quently; simply warm water. | Substances. Mercurial preparations: corrosive sublimate, &c. &c.—Symptoms. Sense of constriction in the throat: mat. ter vomited sometimes mixed with blood.—Antidotes. White of eggs; twelve or fifteen eggs beat up and mixed with a quart of cold water. A glass full every three minutes. Milk, gum-water, linseed-tea. - Substances, Arsenical preparations: white arsenic, &c, &c.— Symptoms. Extreme irritation, pain, sickness, and speedy death, if the poison be not soon counteracted.—Antidotes. Warm water with sugar, in large quantities, to excite vomit- ing. Lime-water, soap and water, pearl-ash and water, muci- laginous drinks. - Substances. Preparations of copper, brass, &c. verdigris, halfpence, pins, &c. &c.—Symptoms. Nearly the same as from mercury-Antidotes. White of eggs: (see under mercury,) mucilaginous drinks. Substances. Preparations of antimony: emetic tartar, &c.— Symptoms. Extreme sickness, with other symptoms of poison, as above stated.--Antidotes. Warm water, or sugar and water; afterwards a grain of opium, or fifteen drops of laudanum every quarter of an hour, for two or three times. Substance. Nitre.—Symptoms. times of blood, &c. &c.—Antidotes. The same as for arsenic, with the exception of lime-water and alkalies. Substance. Phosphorus.—Symptoms. Like mineral acid.— Antidotes. Same treatment as last mentioned. Substances. Lead: sugar of lead, goulard extract, &c.— Symptoms. Great pain in the stomach, with constriction of the throat, &c. &c.—Antidotes. Large doses of Glauber's or Epsom salts, in warm water. - Substances. Opium, henbane, hemlock, nux vomica, deadly nightshade, berries, mushrooms, &c. &c.—Symptoms. Stupor, desire to vomit, heaviness in the head, dilatéd pupil of the eye, delirium, and speedy death.--Antidotes. Four or five grains of tartar emetic in a glass of water; if this does not succeed, four grains of blue vitroil, as an emetic. Do not give large Obstinate vomiting, some- quantities of water. After the poison has been ejected, give vinegar, lemon juice, or cream of tartar. Strong coffee also is useful. * * - - Substance. Poison of the yellow-billed sprat.—Antidote. Solution of sugar. * Opium and arsenic, it is well known, are poisons; and, as the effects of these are often fatal before medical aid can be procured, it may not be improper to state briefly the principal antidotes to either. When poison of any kind has been swal- lowed, the immediate object should always be that of endea- vouring to excite vomiting; but much time is often lost by waiting the operations of medical emetics, when the discharge from the stomach might be much more speedily effected by mechanical means. Let, then, the persons who are about the individual who has taken poison, force a feather, or a piece of stick, or any thing that can be immediately procured, down the throat, and thus continue to irritate the parts till vomiting is induced. Emetics are of course to be administered as soon as they can be procured, when the power of swallowing is not suspended. After the contents of the stomach have thus becn discharged, it is of consequence to recollect that acids are the best correctives of opium, and alkalies of arsenic. In the one case, that of opium, then, let vinegar or lemon juice, diluted with about an equal quantity of water, be freely and copiously administered : in the other, that of arsenic, let a solution of soap in water be made as strong, and poured down as quickly as possible. This last answers a double purpose, the alkali of the soap acting upon the acid of the arsenic, and thus destroy- ing its virulence; and the oily principle of this material, liber- ated in some measure from its alkali, seems to lubricate the coat cf the stomach, and thus at once to abate the inflammation already excited, and to defend the parts from the further influence of the poison. See SYRING e. - - POLACRE, in sea language, a ship with three masts, usually navigated in the Mediterranean ; each of the masts are com- monly formed of one piece, so that they have neither tops or cross-trees, neither have they any horses to their upper yards, because the men stand upon the top-sail yards to loose or furl the top-gallant-sails, and upon the lower yards to loose, reef, or furl the top-sails, the yards being lowered sufficiently down for that purpose. POLAR, relating to the pole. Po LAR Circles. See CIRCLe. POLE, in Astronomy, one of the extremities of the imaginary axis on which the sphere is supposed to revolve. These two points are each 90 degrees from the equator, that towards the north being called the north pole, and the other the south pole. Pole, in Geography, one of the points on which the terraque- ous globe turns, each of them being 90 degrees distant from the equator, and are denominated the north or south pole, accord- ing as they point towards the north or south points of the hea- vens. In consequence of the inclination of the terrestrial axis to the plane of the ecliptic, and its parallelism during its annual motion in its orbit, these parts of the world have only one day and one night throughout the year, each continuing for about six months. It is singular that though the poles have a greater portion of light than any other parts of the globe, yet the name by which they are denoted in most languages, both ancient and modern, is derived from terms signifying darkness and obscurity; but though they really enjoy more light upon the whole than any other parts, yet in consequence of the obliquity with which the rays of the sun fall upon them, and the great length of winter night, the cold is so intense, that those parts of the globe that lie near the poles have never been fully explored, though the attempt has been repeatedly made by the most celebrated navigators. Elevation of the Pole, is an angle subtended between the horizon of any place, and a line drawn from thence to the pole, which is always equal to the latitude of the place. Pole, in Spherics, a point equally distant from every part of the circumference of a great circle of the sphere; or it is a point 90° distant from the plane of a circle, and in a line called the axis, passing perpendicularly through the centre. The zenith and nadir are the poles of the horizon; and the poles of the equator are the same with those of the sphere. P O L P O L DICTIONARY OF MECHANICAL SCIENCE. 821 Machine for Illustrating the Effects of the Centrifugal Force in Flattening the Poles of the Earth.--The following figure repre- sents this machine, which consists of two flexible circular hoops, A B and CD, crossing each other at right angles, and fixed to the vertical axis E F at its lower extremity, but left loose at the pole or intersection E. If this axis be made to revolve rapidly by means of the winch m, and the wheel and Z P- "--- a----- ~~... -- - |→ pinion n, 0, the middle parts A, B, C, D, will, by their centrifu- gal force, swell out and strike against the frame; if the pole E, when sinking, is not stopped by means of a pin E fixed in the vertical axis. The hoops, therefore, have a spheroidal form ; the equatorial being larger than the polar diameter. Poles of the Ecliptic, are two points on the surface of the sphere, 23° 30' distant from the poles of the world, and 90° dis- tant from every part of the ecliptic. Poles, in Magnetism, are two points of a loadstone corre- sponding to the poles of the world; the one pointing to the north, the other to the south. See MAGNETISM. Pole, or Polar Star, is a star of the second magnitude, the last in the tail of ursa minor. Pole, Perch or Rod, in Surveying, is a measure containing sixteen feet and a half. POLE-AXE, a sort of hatchet, nearly resembling a battle- axe, having a handle about fifteen inches long, and being fur- nished with a sharp point, bending downwards from the back of its head. It is principally used on board of ships to cut away the rigging of an adversary who endeavours to board. They have also been sometimes employed in boarding an cnemy whose hull was more lofty than that of the boarders, by driving the points into her side, one above another, and thereby forming a kind of scaling-ladder; whence they are sometimes called boarding-aaces. - POLECAT, in Zoology, the name by which a creature of the weasel kind is known. It is sometimes also called Fitchet, and is remarkable for its stinking smell. This animal proves exceedingly destructive to rabbits when it finds a lodgment in Warrens; many contrivances are therefore made for its destruc- tion. POLEMOSCOPE, in Optics, a kind of reflecting perspective glass invented by Hevellus, who commends it as useful in sieges, &c. for discovering what the enemy is doing, while the spectator lies hid behind an obstacle. POLES, Under Bare, the situation of a ship at sea, when all her sails are furled. See Scu DDING and TRYING. POLICY of AssurANCE, the deed or instrument by which a contract of assurance is effected. POLISHER, or Burnisher, among Mechanics, an instrument for polishing and burnishing things proper to take a polish. POLISHING, in general, the operation of giving a gloss or lustre to certain substances, as metal, glass, &c. The opera- tion of polishing optic glasses, after being perfectly ground, is one of the most difficult points of the whole process. Before the polishing is begun, it is proper to stretch an even well- wrought piece of linen over the tool, dusting upon it some very fine tripoli... Then taking the glass in your hand, run it round forty or fifty times upon the tool, to take off the roughness of the glass about the border of it. This cloth is then to be removed, and the glass to be polished upon the naked tool, with a compound powder made of four parts tripoli mixed with one of fine blue vitriol ; six or eight grains of which mixture are sufficient for a glass five inches broad. This powder must be wetted with eight or ten drops of clear vinegar, in the middle of the tool ; being first mixed and softened thoroughly, with a very fine small mullet. Then, with a nice brush, having spread this mixture thinly and equably upon the tool, take some very fine tripoli, and strew it thinly and equably upon the tool so prepared, after which, take the glass to be polished, biped very clean, and apply it on the tool, and move it gently twice or | thrice in a straight line backwards and forwards; then take it off, and observe whether the marks of the tripoli, sticking to the glass, are equably spread over the whole surface; if not, it is a sign that either the tool or glass is too warm, in which case you must wait a while and try again, till you find the glass takes the tripoli every where alike. Sir Isaac Newton no where expressly describes his method of polishing optical glasses; but his method of polishing reflecting metals, he thus describes in his Optics. He had two round copper plates, each six inches in diameter, the one convex, the other concave, ground very true to one another. On the con- vex one he ground the object-metal, or concave, which was to be polished, till it had taken the figure of the convex, and was ready for a polish. He then pitched over the convex very thinly, by dropping melted pitch upon it, and warming it to keep the pitch soft, whilst he ground it with the concave copper wetted, to make it spread evenly all over the convex, till it was no thicker than a sixpence; and after the convex was cold he ground it again, to give it as true a figure as possible. He then ground it with very fine putty, till it made no noise; and then upon the pitch he ground the object-metal with a brisk motion, for two or three minutes; when laying fresh putty upon the pitch, he ground it again till it had done making a noise, and afterwards ground the object-metal upon the pitch as before ; and this operation he repeated till the metal was perfectly polished. See LENs and SPECULA. The Parisians have now introduced an entirely new mode of polishing, which is called plaque, and is to wood precisely what plating is to metal. The wood, by some process, is made to resemble marble, and has all the beauty of that article, with much of its solidity. It is even asserted by persons who have made trial of the new mode, that, with the exception of the actual strength of marble, it has no qualities superior to the imitation, upon which water may be spilled without staining, and it will resist scratching in the same degree as marble. Method used in Germany for Warnishing Wood.—In the first place, the Germans are careful to join their wood very neatly, and to make the surface very smooth, because if the varnish brings out the beauty of the wood, it does the same by the defects. When the wood is once well polished, they prepare the varnish. For this purpose they reduce to a powder some of the purest shell lac, that is to say, very transparent, and dis- solve it in well-rectified spirits of wine ; they add, in a retort, double the quantity of alcohol to the lac employed, and expose it to a heat of about fifty degrees Reaumur. They are careful to agitate the mixture every three hours, until the varnish has acquired the suitable consistence; if it does not appear of a sufficient consistence, they add a little more pulverized lac ; if on the contrary it is too thick, they mix a little more alcohol, being careful to agitate the mixture until it is of the right thick- ness. This warnish has no peculiar quality, except that it con- tains no turpentine, nor any other body that renders the varnish gluey, and liable to crack. . They apply the varnish with a piece of fine linen, which is formed into a sort of pallet. The workman is previously provided with a mixture of two parts of varnish to one of olive oil, in which he soaks the linen, and then rubs it over the surface of the wood with great force, and press- ing very hard upon it, but always in the direction of the fibres of the wood. He begins afresh by moistening the wood again, until the whole surface of the wood is covered with a slight coat of varnish. When the wood is well moistened with the 9 Z. - 822 P O L .P O L DICTIONARY OF MECHANICAL scIENCE. varnish, they leave it to dry, which it does very quickly, and they then apply a second coat, a third, and even a fourth if neces- sary. fine linen in a mixture of olive oil and tripoli reduced to powder, and rub the wood hard with it until the varnish has acquired the proper degree of brilliancy. Then, to give it the last polish, they rub it with a piece of very soft linen, or very fine soft leather. This varnish may also be applied with a brush, on bodies that do not offer an even surface, only it must then be made thinner, by adding a greater proportion of alcohol. It may afterwards be polished in the manner above described. When it is applied to bodies of great surface, it is essential that the warnish be made as thin as for bodies in relief, because as it dries quickly, the edges of the parts that are first laid on would acquire a degree of thickness which could not be reduced in the polishing. Lastly, articles that are turned in wood may be varnished and polished in the same manner even in the lathe. The only inconvenience attending this varnish is, that it gives the wood a brownish colour, which is no inconvenience where a deep colour is desired; and for which reason, it is much used in varnishing mahogany and the walnut and cherry tree woods. 1But when the wood is to be kept of a light colour, the varnish is made in the same manner, only, instead of the lac, they use copal gum dissolved in the alcohol, adding to it sometimes a little camphor or ether. This varnish may be applied with success to many different sorts of wood. Some of the Vienna makers dissolve the copal by exposing it to the action of the vapour of alcohol, and sometimes they colour the copal varnish, which is naturally colourless, with any tint they may wish to give it; and they do not seem to use any spirits of turpentine to dissolve the copal. By this method of applying varnish to wood, it penetrates so completely into the grain, that it is almost impossible to crack it. So that when scraped, even with a sharp instrument, if the traces be not very deep, the polish may be restored by hard rubbing with a soft piece of linen. The gluey varnishes have not this advan- tage, since they do not penetrate so deep into the substance of the wood, and a scratch will take them almost clean off, in such a manner that no friction will restore the polish. POLITICAL AR1th Metic, calculations relating to the wealth of nations. Political arithmetic does not determine in what natural wealth truly consists, but estimates the value of what- ever passes under this name, and distinguishes the propor- tions in which the component articles may be applied to pur- poses conducive to the safety or prosperity of the community. PoliticAL Economy, is the science which treats of the wealth nations. Its object is to ascertain, in the first place, wherein wealth consists, and then to explain the causes of its production, and the principles on which it is distributed through the dif- ferent orders of society. It likewise endeavours to point out the tendency which any political regulations may have to favour or to injure the productions, or most advantageous distribution of wealth. Such is its peculiar object; and consequently, though writers on political economy"may frequently treat on the more important topics of national security, freedom, and happiness, they are then passing the strict limits of their science. POLL, a word used in ancient writing for the head. ' Pol, L. Momey, a capitation or tax, imposed by the authority of parliament on the head or person either of all indifferently, or according to some known mark of distinction. POLLUX, in Astronomy, one of the Twins in the constella- tion Gemini; also a fixed star of the second magnitude in that constellation. See GEMINI. POLYACOUSTIC, any thing that multiplies sound. POLY GAMY, the plurality of wives or husbands, in the pos- session of one man or woman at the same time. POLYGLOTT, among divines and critics, chiefly denotes a bible printed in several languages. POLYGON, in Fortification, denotes the figure of a town, or other fortress. - - Line of PolyGo Ns, on the French sectors, is a line containing the homologous sides of the first nine regular polygons inscribed in the same circle; that is, from an equilateral triangle to a dodecagon. - - , When the varnish is perfectly dry and hard, they give it the lustre in the following manner:—They steep a piece of POLYGON, in Geometry, a multilateral figure, or a figure whose perimeter consists of more than four sides, and conse- quently having more than four angles. If the angles be all equal among themselves, the polygon is said to be a regular one; otherwise it is irregular. Polygons also take particular names according to the number of their sides; thus a polygon of - 3 sides is called a trigon, 4 sides is called a tetragon, 5 sides is called a pentagon, 6 sides is called a hexagon, &c. and a circle may be considered as a polygon of an infinite number of small sides, or as the limits of the polygons. Poly- gons have various properties, as below:— 1. Every polygon may be divided into as many triangles as it has sides. 2. The angles of any polygon taken together, make twice as many right angles, wanting 4, as the figure hath sides; which property, as well as the former, belongs to both regular and irregular polygons. I - 3. Every regular polygon may be either inscribed in a circle, or described about it; which is not necessarily the case if the polygons be irregular. But an equilateral figure inscribed in a circle is always equiangular; though an equiangular figure inscribed in a circle is not always equilateral, but only when the number of sides is odd. For if the sides be of an even number, then they may either be all equal, or else half of them may be equal and the other half equal to each other, but dif- ferent from the former half, the equals being placed alternately. 4. Every polygon, circumscribed about a circle, is equal to a right-angled triangle, of which one leg is the radius of the circle, and the other the perimeter or sum of all the sides of the polygon. Or the polygon is equal to half the rectangle under its perimeter and the radius of its inscribed circle, or the perpendicular from its centre upon one side of the polygon. Hence the area of a circle being less than that of its circum- scribing polygon, and greater than that of its inscribed polygon, the circle is the limit of the inscribed and circumscribed poly- gons: in like manner, the circumference of the circle is the limit between the perimeters of the said polygons. See CIRCLE. 5. The following table exhibits the angles and areas of all the polygons, up to the dodecagon, viz. the angle at the centre, the angle of the polygon, and the area of the polygon when each side is 1. No. of w Ang. F. at Ang, C. of Sides. . Name of Polygon. &: Polygon. Area. 3 Trigon,.......... 1200 600 0.4330127 4 Tetragon, ... . . . . 90 90 1°0000000 5 Pentagon, ... . . . . 72 108 I •7204774 6 Hexagon, ... . . . . 60 120 2 5980762 7 Heptagon, . . . . . . 51; 128} 3°6339 124 8 Octagon, ....... 45 135 4'8284271 9 Nonagon, ... . . . . 40 140 6'1818242 10 |Decagon, ........ 36 144 7-6942088 11 Undecagon,..... 32; 147# 9-3656399 12 |Dodecagon, ..... 30 150 11' 1961524 Therefore to find the area of any regular polygon not exceed- ing 12 sides, square the side, and multiply that square by the corresponding tabular number in the preceding table. Or gene- rally, if s represent the length of one of the equal sides, and n 72. 90 m — 180 the number of them ; then s” x 4 tang.( i-y = area of the polygon. To inscribe a Polygon within, or to circum- scribe a Polygon about a given Circle.—Bi- sect two of the angles of the given polygon A and B by the right lines A O, B O ; and from the point O, where they meet, with the radius A. O, describe a circle which will circumscribe the polygon. Next, to circumscribe a polygon divide 360 by the number of sides required to find the angle * *** * -sº- * P O L. A O B ; which set off from the centre O, and draw the line A B, ^n which construct the polygon as in the following problem. 2. On a given line to describe any given regular polygon. Find the angle of the polygon in the table, and at A set off an angle equal thereto ; then drawing C A = A B, through the points C A B, describe a circle, and in this applying the given right line as often as you can, the polygon will be described. Otherwise. To inscribe a Polygon in a Circle.—Draw the diameter A B, which “...C.--- divide into as many equal parts as the ..” figure has sides. From the points A, B, •' ' as centres with the radius A B, describe arcs crossing each other in C. From the point C, through the second division of the diameters, draw the line C D. Join the points A, D, and the line A D will A be the side of the polygon required. Note.— In this construction A D is the side of a pentagon. Another method, something more ac- . curate, is by erecting a perpendicular from the centre of such a length that the part without the circle shall be equal to # of that within, and drawing a line from its extremity through the second division as before. In the preceding part of the article it is observed, that any regular polygon may be inscribed in, or circumscribed about, a circle : but this must be understood under certain modifications; all that is meant is, that there is nothing in the nature of the problem to render it impossible; and not that any polygon may be geometrically inscribed. In fact, the number of poly- gons that admit of a geometrical construction is very limited, viz. the equilateral triangle, the square and pentagon, and those figures whose number of sides are some multiples of these ; to which Gauss has lately added the 17-sided polygon, and its multiples, and some others, viz. all those polygons whose num- ber of sides is a prime, and of the form 2m+ i. . POLYGONAL Numbers, are those that are formed of the sums of different and independent arithmetical series, and are termed Natural, Triangular, Quadrangular, Pentagonal, Heara- gonal, &c. Numbers; according to the series from which they generated. - Lineal, or Natural Numbers, are formed from the successive sums of a series of units; thus, Units . . . . . . . . © e º e º e º 'º . . . . . . . . 1, 1, 1, 1, 1, 1, &c. . 1, 2, 3, 4, 5, 6, &c. Triangular Numbers, are the successive sums of an arithme- tical series, beginning with unity, the common difference of which is 1; thus, Arith. Series . . . . . . . . . . . 1, 2, 3, 4, 5, 6, 7, &c. Trian, num. . . . . . . . . . . . . 1, 3, 6, 10, 15, 21, 28, &c. Quadrangular, or Square Numbers, are the successive sums of an arithmetical progression, beginning with unity, the com- mon difference of which is 2; thus, - Arith. Series. . . . . . . . . . . ... 1, 3, 5, 7, 9, 11, 13, &c. Quad, or squa... . . . . . . . . 1, 4, 9, 16, 25, 36, 49, &c. Pentagonal Numbers, are the sums of an arithmetical series, the common difference of which is 3; thus, Arith. series 1, 4, 7, 10, 13, 16, 19, &c. Pentagonals . . . . . . . . . . 1, 5, 12, 22, 35, 51, 70, &c. And, universally, the migonal Series of Numbers, is formed from the successive sums of an arithmetical progression, begin- ning with unity, the common difference of which is m — 2. POLY GONOMETRY, is an extension of the science of trigonometry, having the same reference to polygons in general, as trigonometry has to triangles in particular. We owe this extension of the rules of trigonometry to L'Huiller, who pub- lished a treatise on this subject at Geneva, in 1789; which, with the exception of a chapter in the third volume of Dr. Hutton’s “Course of Mathematics,” is, we believe, the only work on polygonometry at present before the public. POLYGONUM Bistory A. (Bistort.) The Roots. All the parts of the bistort have a rough austere taste, particularly the root, which is one of the strongest of the vegetable astringents. It is employed in all kinds of immoderate haemorrhages and other fluxes, both internally and externally, where astringency is the only intention. It is certainly a very powerful styptic, DICTIONARY OF MECHANICAL scIENCE P O N 828 and is to be looked on simply as such ; the sudorifie, antipesti- lential, and other like virtues attributed to it, it has no other claim to, than in consequence of this property, and of the anti- septic power which it has in common with other vegetable styptics. The largest dose of the root in powder is one dram. PolyGo NUM Fagopyrum. (Buck Wheat.) This is usually sown in places where pheasants are bred, as the seed is the best food for those birds; it is also useful for poultry and hogs. We have eaten bread and cakes made of the flower, which are . also very palatable. Two bushels are usually sown per acre. The season is May; and it is often sown on foul land in the summer, as it grows very thick on the land, and helps to clean it by smothering all the weeds. The crop does not stand on the ground more than ten or twelve weeks. - POLY GRAM, a figure consisting of many lines. POLYHEDRON, or Polyed Ron, abody or solid contained by many rectilinear planes or sides. When the sides of the polyhedron are regular polygons, all similar and equal, then the polyhedron becomes a regular body, and may be inscribed in a sphere; that is, a sphere may be described about it, so that its surface shall touch all the angles or corners of the solid. There are but five of these regular bodies, viz. the tetrahedron, the heasahedron or cube, the octahedron, the dodecahedron, and the icosahedron. Poly Hed Ron, Gnomonical, is a stone with several faces, on which are projected various kinds of dials. Of this sort, that in the Privy Garden, London, now gone to ruin, was esteemed the finest in the world. - - POLYNEMUS, the Polyneme, in Natural History, a genus of fishes of the order abdominales. Shaw enumerates ten spe- cies; Gmelin only four. The Paradise polyneme, or mango fish, inhabits the Indian and American seas, and is thirteen inches long, elegantly shaped, and with thoracic filaments fre- quently far larger than the body; its colour is yellow. At Cal- cutta it is in the highest estimation for the table. The gray polyneme abounds on the Malabar coast, and has five filaments on each side, but all rather short. It is sometimes four feet long, and is in some parts of India denominated the royal fish, from its extraordinary excellence. The polyneme of the Nile is, both in form and taste, superior to every other fish in the rivers which flow into the Mediterranean or Atlantic seas. It is covered with scales resembling the most brilliant silver spangles, and is of the weight of thirty, in some instances of seventy pounds. It is a native of the Nile, and Bruce has minutely detailed the process adopted by the Egyptians for taking it, by a cake of flour, dates, and other ingredients, with a considerable number of hooks concealed in it; but attached to a string held by the fisherman, who floats on the stream upon a blown-up goat's skin, in order to sink this mass, and then re- turns to the bank. He then fixes the line to some tree, connect- ing it with a bell, the sounds of which give him notice of the suc- cess of his experiment, being produced by the twitchings and pulls of the fish. - - POLY NOMIAL, in Algebra, a quantity consisting of many terms. POLYPUS, the popular name for those fresh water insects which class under the genus of hydra, of the order of vermes zoophytae. POLYSCOPE, or PolyhedroN, in Optics, a multiplying- glass, or one which represents a single object to the eye, as if there were many. It consists of several plane surfaces, dis- posed under a convex form, through each of which the object is SC 62n. r POMELION, a name given by seamen to the cascabel, or hindermost knob of a cannon. * . PON CHES, small bulk heads made in the hold to stow corn, goods, &c. * * * PONDERABILITY, a contingent property of bodies. Every substance within the sphere of observation is found to possess weight, or a disposition to gravitate towards the centre of the earth. But to constitute gravity, it is not required that a body should invariably fall to the ground. Smoke ascends in the atmosphere, and a lump of lead rises in a tub of mer- cury, from the same cause that a pine tree plunged into a lake mounts again to the surface. Withdraw the air, the mercury, | and the water, which supported those comparatively lighter 824 P O N P O N DICTIONARY OF MECHANICAL SCIENCE. substances, and the smoke, the lead, and the timber, will imme- diately descend. Pour mercury over a smooth piece of cork, applied to the bottom of a glass, and it will remain in the same 'situation, while an iron ball can be set to float on the liquid metal. The order of nature might here seem to be reversed. But, since mercury does not insinuate itself through a very marrow interstice, it merely rests on the upper side, without pressing against the under side, of the cork. If levity, how- ever, as the schoolmen asserted, had been a real property belonging to certain bodies, the smoke and the cork would, in every instance, have occupied the lower stations. But the weight of a body is not the same in all places and situations. A lump of lead, which weighs a thousand pounds at the surface of our globe, would lose two pounds, as indicated by a spiral spring, if carried to the top of a mountain four miles high; and, if it could be conveyed as deep into the bowels of the earth, it would lose one pound. The same mass transported from London to the Pole, would gain the addition of 2 lbs. 769 decim. parts, (nearly 3 lbs.); but if taken to the Equator, it would suffer a loss of 44 lbs. The variable, and therefore contingent, weight of bodies, is only the gradation of that mutual and uni- versal tendency, diminishing as the square of the distance, which retains the moon in her orbit, and upholds the circula- tion of the whole system of planets around the sun. The gra- vitation even of small masses towards each other, such as balls of lead separated only by the interval of a few inches, has been detected by delicate experiment, and reduced to rigorous cal- culation. But when the approximation is closer, this force acquires a modified character, and passes into cohesion. Thus, if two leaden bullets have a little portion of the surface of each pared clean, and be then pressed together with a slight twist, they will cohere firmly into one mass. In the same manner, gold or silver foliage, and other ornaments, struck with a heavy hammer into the surface of polished iron or steel, become per- manently united. Within other limits, the tendency to mutual approach is changed into an opposite quality. Thus, drops of rain or dew, run along the smooth and glossy surface of a cab- bage leaf without spreading. If the dust of the lycopodium, or club ferm, or even fine pounded rosin, be strewed on water contained in a glass, any smooth rounded piece of soft wood will float upon it, or may be immersed in the liquid, without being wetted, the powder preventing, by its repulsion, all con- tact of the water. A fine needle, laid on the surface of water, makes a dimple in which it swims. On the same principle, the slender limbs of insects, and the minute down which covers their wings, protects them from the penetration of humidity. If the hand be rubbed with linseed oil, it may be plunged with impunity for a few seconds in boiling water, the oil repelling the water, and consequently checking the communication of heat. The application of palm soap to the skin is still more effectual. It thus appears that bodies are indefinitely porous, compres- sible without limits, and capable of assuming all variety of forms. How different is the constitution of ice, of water, and of steam? Consider what mutable aspects mercury exhibits. Beginning at a low degree of cold, and ascending through the gradations of heat, we find it a friable solid, next a shining | liquid, then a penetrating vapour, and lastly, a fine red powder, A bright ductile piece of metal passes successively into an earthy oxide and pellucid glass. Charcoal is precisely of the same nature as the diamond; yet what a contrast between the dingy appearance of the one, and the dazzling lustre of the other?. How variously are substances transformed by the operations of art? The skins of animals become changed into parchment and different kinds of leather, and its shreds into glue. The animal fibres are converted into matting, cordage, and linen cloth; and the rags, again, reduced to a pulp, and manufactured into paper. How diversified appear the compounds of the farinaceous substances? By a distinct operation, the same grain produces gruel, bread, biscuit, starch, and a hard pellucid concretion resembling mother-of-pearl. But the plastic powers displayed in the process of vegetation and animal life, infinitely surpass the resources of art. Many plants are fed by water and air alone, and consequently these fluids are capable of being trans- formed into all the various products. In short, nature ex- hibits only a chain of endless metamorphoses: the substance or material remains unchanged, but its form undergoes con- tinual mutations. - - The properties of bodies result from those of their component particles. At certain mutual distances they remain quiescent; but, at other distances, they shew a disposition either to approach or to recede. Such opposite tendencies are com- monly referred to the principles of attraction and repulsion. But all those diversified effects may be comprehended under a general law, which connects the mutual action of particles with their distance. In the language of modern analysis, the corpuscular energy is always some function of the distance; and it may be represented by an extended curve, of which the abscissae mark the distances, and their ordinates express the corresponding forces. Fig. 1, exhibits this curve of primordial action; in which A denotes an action or ultimate particle, and B, C, D, E, &c. the successive positions of another particle, the perpendiculars Mſ. Fig. 1. g A B C wº #–3 ey- • X - JN - D CM, E N, GO, IP, L Q, o &c. representing their mutual action attractive between B and D, F and H, K and X, when above the axis AX, and repulsive between D and F, H and K, below it. The final branch of the curve must gradually assimilate itself to the law of universal gravitation. 'But the primary branch of the curve must, in like manner, con: tinually approach AY, the perpendicular to the , axis; and since no pressure or impulsion can ever accomplish the pene- tration of matter, it follows, from the principles of Dynamics, that the space included between the curve and that asymptote must be finite. Where the curve repeatedly grosses the axis, are so many quiescent positions, B, D, F.H. K., &Q. in any one of which a particle would continue in equilibrio. But this equi- librium is of two kinds, the stable or the instable; the former easily recovering itself from any slight displacement, and the latter, when once disturbed, being irremediably dissolved. If the curve in its progress cross the axis from the side of repul- sion to that of attraction, its intersection will evidently be a point of stability; for if a particle be pushed inwards, it will then be repelled back again; and if it be pulled outwards, it will experience an attractive force, which will recall it to its first position. But if the curve pass from attraction to repul- sion, its intersection with the axis is a point of instable equili- brium; for, in proportion as a particle is pressed inwards, it will be pulled forcibly from its position; and if it be drawn outwards, the repulsion, now conspiring, will bear it along with accumulating power. Thus, B, F, and K, the transitions from repulsion to attraction, are points of stability; but D and H, the opposite transitions, are points of instability. Fig. 2. t *~, A "l. 4–2– * ty According as the ordinates, near the points of transi- tion, increase less or more rapidly, the tendency of the particles to coalesce, or to separate, will be proportion- ally feeble or intense. If the curve cut the axis very obliquely, therefore, it will mark, a limit of languid cohesion, as at the point F; but if it shoot nearly at right angles across the axis, as . at B or K, it will in- dicate a limit of powerful cohesion. Those atoms, or ultimate particles, have no sensible magnitude. But # though the range of our conceptions may be un- *** * * * * ~ * = - - , P o o P O O 825 DICTION ARY OF MECHANICAL SCIENCE. bounded, every thing in the material world appears to be distinct and determinate. Experience indeed informs us, to what astonishing degree matter can be attenuated, but phi- losophy descries the existence of certain fixed or impas- sable limits, at which the capability of farther subdivision utterly ceases. The primordial line of action is hence a phy- sical, and not a mathematical curve; or it is not strictly incur- wated at every point, but proceeds by successive minute deflec- tions, corresponding to the breadth of the elementary particles. Such a modification of the curve is represented by fig. 2; being a serrated line, whose gradations answer to the successive stages of corpuscular action. Continuous shades, indeed, exist only in our modes of conception, and nature exhibits always individual objects, and advances by finite steps. The material world is hence reducible to atoms, actuated by forces depend- ing merely on their mutual distances. From such simple elements, the different arrangements of the particles, and their multiplied interior combinations, this sublime scene of the universe derives all its magnificence and splendour. PONTON, or Pontoon, in War, denotes a little floating bridge made of boats and planks. The ponton is a machine consisting of two vessels at a little distance, joined by beams, with planks laid across for the passage of the cavalry, the can- non, infantry, &c. over a river, or an arm of the sea, &c. See BRIDGE. - - PONTOON, in Naval affairs, a large low flat vessel, nearly resembling a barge of burden, and furnished with cranes, cap- stans, tackles, and other machinery necessary for careening ships; these are principally used in the Mediterranean, bui very seldom in the northern parts of England. - Po NToo N, or Ponton, a kind of flat-bottomed boat, whose carcase of wood is lined within and without with tin. They are generally twenty-one feet long, five feet broad, and two feet one inch and a half deep within. POOP, the highest and aftmost deck of a ship. To have the Wind in Poop, is to have it behind or favourable. Poop Royal, a short deck, or platform, placed over the aft- most part of the poop in the largest of the French and Spanish men of war, and serving as a cabin for their masters and pilots. This is usually called the top-gallant-poop by our shipwrights. POOPING, the shock of a high and heavy sea upon the stern or quarter of a ship, when she scuds before the wind in a tempest. This circumstance is extremely dangerous to the vessel, which is thereby exposed to the risk of having her whole stern beat in, by which she would be laid open to the entrance of the sea, and most probably founder. Poopi NG, implies also the action of one ship running her stem against another's stern. - - - - - POOR LAWS. Of the general outline of this most enor- mous, and almost ineffectual burden on the people, much has been said in the excellent treatise of Mr. Colquhoun. The 43 of Eliz. c. 2, is the foundation of all that is good in the poor-laws; making provision for finding work for the industrious and able; for compelling the idle and able to labour; and for affording relief to the diseased and impotent; and the 13, 14, Charles II. c. 12, is the foundation of all that is evil, by forming the system of settlements and removals; a system establishing oppression, litigation, and expense, and which has been made more oppressive, and more productive of litigation and expense, by every subsequent statute, till the statute of the 35th of his late Majesty; which, by forbidding removals in case the pau- pers is not absolutely chargeable, has remedied more than half the evils occasioned by the former laws. \ Overseers.-The churchwardens of every parish, with two, or three, or four substantial householders, according to the size of the parish, to be nominated in Easter week, or within a month after, under the hands or seals of two or more neighbouring jus- tices, and who shall be called overseers of the poor. 43 Eliz. c. 2. s. 1. Where there are no churchwardens, the whole power is vested in the overseers, 17. Geo. II. c. 38, s. 15. Overseer dying or becoming incapable of acting, two justices may ap- point another. Ibid. s. 3. If any person shall find himself aggrieved by any act of the justices, appeal to the sessions whose determination shall be final. Ibid. s. 6. Where there is no nomination of overseers, penalty 5l. on every justice of the division. Recovery by distress from the sessions, to be levied 84. - tices by the poor for an appeal to the sessions. 6, 11–Overseers, within four days of the end of their year, shall account to two justices of all sums received and paid, and ; pay over what remains to their successors; who in default may levy it by distress, under warrant of two justices; who, in de- fault of distress, may commit till paid. Ibid. s. 2, 4.—Every parish officer neglecting to obey the regulations of the above act, penalty from 40s. to 5l. to two justices by the poor. 17 George II. c. 38, s. 14.—Parish officer neglecting his duty, or disobeying the warrant of a jus- tice, penalty 40s. to be recovered by distress, and, in default, for apprenticing poor children. by the churchwardens and overseers. .43 Elizabeth, c. 2, s. 10. Parish officers with the consent of two justices shall set children to work, whose parents cannot maintain them, and all persons married or single who cannot maintain themselves, and have no regular trade or calling; and one justice may send persons to the house of correction who will not work; and the parish offi- cers, not having an excuse, to be allowed by two justiccs, shall meet once in a month at least, in the church, on a Sunday after evening service, to consult. Penalty 20s. Recovery by distress, and, in default, commitment till paid.—Application to two jus- Ibid. s. 1, 2, Recovery by distress. Application commitment not exceeding ten days, before two justices of the poor for an appeal to the sessions, giving ten days notice. 33 George III. c. 55, s. 1, 2. Rate.—Parish officers shall raise by a rate on all the inhabi- tants, a stock of flax, &c. to set the poor to work, and sums for the relief of the old and lame who are not able to work, and - - Rate to be made by consent of two justices. 43 Elizabeth c. 2, s. 1.-Parish officers shall cause notice to be given publicly in the church, of such con- sent of the justices, the next Sunday; and no rate shall be col- lected till such notice is given. shall permit the inhabitants to inspect such rates at all season- able hours, on payment of 1s. ; and give copies, on payment of 6d. for every twenty-four names. to the party aggrieved. Ibid. s. 2, 3.-Persons aggrieved by 17 George II. c. 3, s. 1. They Penalty 20s. Application assessment appeal to the sessions. 17 George II. c. 38, s. 4. Goods of persons refusing to pay may be distrained in any part of the county; and of any other county, on oath made before a justice of such other county, which oath shall be certified in the warrant. Appeal to the sessions of the county where the assessment was made. Ibid. s. 7. If two justices perceive that the inhabitants of any parish are not able to levy money sufficient for the relief of the poor, they shall assess any neigh- bouring parishes within the hundred, in aid; and if the hundred be not of sufficient ability, then any parishes within the county, 43 Elizabeth, c, 2, s. 3. Father, grandfather, mother, or grand- mother, of persons wanting relief, shall maintain them ; penalty 20s. per month. Recovered by distress, and in default commit- ment till paid. Application to two justices by the poor. Ibid. s. 2, 11. Fathers leaving their wives and children, and mothers their children chargeable to the parish, having ability to maintain them, the parish officers, where such are left, may, by warrant of two justices, seize so much of the goods and chattels, or receive so much of the annual rent as such justices shall appoint, to reimburse the parish: and such order to be confirmed by the sessions. 5 George I. c. 8, s. 1. Parish officers, with consent of the lord of the manor, may, by order of two justices, ercet cottages on waste lands, for the poor. 43 Elizabeth, c. 2, s. 5. They may also, with consent of two justices, set up trades, &c. for the employment of the poor. 3 Charles II. c. 4, s. 22. Relief—Parish officers, with consent of the majority of the inhabitants, may contract with any person for the lodging, keeping, maintaining, and employing the poor; and persons refusing such relief are not entitled to any other, 9 George I. c. 7, s. 4. The abominable oppression of this execrable law has, however, been removed by another humane statute of the late reign ; for by 36 George III. c. 25, s. 1, 2, 3, it is enacted, that it shall be lawful for the parish officers, with the approbation of one justice, in writing, to relieve any industrious person at his own habitation, under certain circumstances of temporary illness, or distress; and one justice may order such relief for any time not exceeding one month, provided the cause be writ- ten on the back of the order, which the parish officers are bound to obey; and two justices may continue such orders from time to time, each period in succession not being more than 10 A 826 P O P. P O O Diction ARY OF MECHANICAL scIENCE. one month. A justice or a medical man, or clergyman by warrant of a justice, may visit, workhouses, and examing the state of them, and hear complaints, and certify to the sessions; and if there should be any infectious disorder, the visiting jus- tice shall apply to another justice, or any other person visiting, to two justices; which two justices shall order such regula- tions as they deem necessary till the next sessions. , 30 George III, c. 49, s. 1, 2. Names of persons receiving parish relief to be entered in a book. , 3 William, c. 11, s. 11. ...And no other person to be relieved but by order of a justice, Ibid. No relief to be ordered by a justice unless for a reasonable cause, proved on oath, and unless the pauper shall have first applied io a parish officer or a vestry, nor before the justice shall have summoned the parish officers. 9 George I. 6, 7, S. 1. The name of such persons to be entered with the others; and no parish officer, except on sudden emergency, shall bring any charge on the parish for porsons not registered. Penalty 6l. Recovered by distress. Application to two justices by the poor. Ibid. 8, 2. - Settlements.-The general heads on which settlements are founded are birth, apprenticeship, scrvice, serving offices, rent- ing 101, per annum, marriage, and estate. A house at not less than 101, per annum, for at least one whole year, for which term rent and taxes must be paid and occupied. 1. Birth.—Children prima facie, whether bastards or legi- timato, are settled where born ; but with respect to bastards, if a woman goes collusively to be delivered in another parish, the child gains no settlement there. Bastards born during an order of removal, or the suspension of it, belong to the mother's parish. 35 George III. c. 101, s. 6. And so of bastards born in vagrancy. 17 George II, c. 5, s. 25. And so if born in houses of industry in incorporated districts. 20 George III. c. 36. Or in friendly societies. 33 George III. c. 54, s. 25. Or in lying- in hospitals, 13 George III. c. 82. Legitimate childrcn are settled as their parents, till old enough to gain a settlement of their own, the earliest period of which is scven years: at which age, by 6 Elizabeth, c. 5, s. 12, a child may be apprenticed to a person using the seas; and by 17 George II. c. 5, justices may bind the child of a vagrant of the same age; and any appren- tico gains a sottlemcnt in a place where he has resided as such for forty days. X. 2. Apprenticeship. The time required to gain a settlement has just been mentioned. The apprentice must be legally bound, except that the contract not being indented, which is fatal in every other case, is not in this. 31 George II. c. 11. 3. Service. —Unmarried persons without children, hired and serving for a year, gains a settlement. 3 William, c. 11, But must continue a whole year in such service, 8, 9 William c. 30. Serving a certificated member of a benefit society no settlement. 33 George III. c. 54, s. 24. Forty days’ residence in the place mccessary, but they necd not be all together. Where the last forty days are in diſſerent places, settlement where the scrvant slept the last night. General hiring dccmcd hiring for a year. Hiring for a year, with liberty to be absent at harvest, sheep- shearing, &c, gains no Sottlemont; but to scrve a month in tho militia docs, Hiring for one day short of a year, no settlement. Scrving for three hundred and sixty-ſive days, if leap year, no scttlement. Hiring at so much per week, conditionally to part at a month's warning, deemed a gencral hiring; and as such, a hiring for a year. 4. Serving Offices.—Persons coming to inhabit a placc, and oxcouting any annual and public office for a year, settlement. 3 William c. 11, s. 6. 5. Marriage.—As a general rule, the wife follows the hus- hand's settlement; but if the husband has no settlement, or it is not known at his death, her own settlement is restored. And if the husband deserts his wife, her settlement remains, except natives of Scotland, Ireland, the Isle of Man, Guernscy, or Jersey, who have no legal settlement, and may be sent home, on becoming chargeable, at the expense of the county. G. Estate.—No person shall be removed from any cstate while he remains on it. 9 George I. c. 7. But no person gains a settlement by an estate whose purchase was less than 30l. Ibid, Persons who have no sottlement, as foreigners, or whose sctlement cannot be known, as deserted infants, must bo kept by the parish where thcy happen to be. " Removals.--So much of 13, 14 Charles II, c. 12, as enables justices to remove persons likely to become chargeable, is re- pealed; and no person can now be removed until actually chargeable. 35 George III. c. 101, s. 1. Justices may suspend removal of persons ill, either under a vagrant pass, or order of removal; expense attending the suspension to be paid by the parish officers of the place to which the pauper is to be removed ; on refusal to pay within three days, to be recovered by distress and sale with costs not exceeding 40s. One justice. If out of the jurisdiction, warrant of distress to be backed by a justice having jurisdiction. Appeal to the sessions, if charges and costs exceed 20l. Ibid. s. 2. Every person oonvicted of larceny or felony, or deemed a rogue and vagabond, or disorderly per- son, or who shall appear to two justices, on oath of one witness, to be a person of evil fame or a reputed thief, and shall not give a satisfactory account of himself and way of living, and every unmarried woman with child, shall be deemed actually chargeable, and shall be removed as such. Ibid. s. 6. Persons refusing to go with an order of removal, or returning when removed, to be committed as a vagabond. One justice. 13, 14, Charles II. c. 12, s. 3. Parish officer refusing to receive a per- son so sent, to be bound to the assizes or sessions to answer the contempt. One justice. Ibid. If removed into another county "...º.º. and the parish officer refuse to receive, penalty 6l. Application to the parish of the place, from which the pauper is removed. Recovery by distress, and, in default, commitment for forty days. One justice of the jurisdiction to which removed. Two witnesses, 3 William, c. 11, s. 10. Appeal from orders of removal to the sessions of the county from which the Nauper was removcd. 8, 9 William, c. 30, 8.6. It must be to the sessions of the county, and not of any corporate town. Poolt’s Itate, an assessment raised through England and Wales, for the temporary relief, or permanent maintenance, of all such persons as from age, infirmity, or povorty, cannot them- selves procure the means of subsistence. The total sum raised by the poor's rate and other parochial rates within the year, ending Easter 1822, was 7,695,5341. of which 6,358,702). were expended in support of the poor, and 1,336,6321. for other pur- poses. The poor's rate has gone on at an alarming increase since the peaco in 1815, in which year 5,418,845.l. were cz- ponded in their support. POPE, Papa, Father, the sovereign pontiſſ, or supreme head of the Romish church. POPULATION of the World, agreeably to a general census framed in the year 1825, from which it would appear, that under the metaphysical titles following, thc whole human race are said to stand thus:– Jews, . . . . . . . . . tº 6 e º e º 'o º . . . . . . . . . . . 4,000,000 Pagans, . . . . . . . . . . . . . . . . . . . . . . . ... 456,000,000 Mahomcdans, . . . . . . . . . . . . . . . . . . ... 140,000,000 Christians, tº e º 'º e º e º º * * * * * * s tº a t w w w w e 200,000,000 Total, . . . . . . . . . . . . 800,000,000 Dcists and Athcists are comprehended, but not distinguished in either of those enumerations, as they do not avow them- solves by any formation into bodies, but are anomalics in each class.--It is worthy of notice, that the most ancient congrega- tion, viz. Pagans, 8till subsist throughout the globe, and comprise more than one-half of its general population; that the socond in order of time, viz. Jews, have, since the destruction of their temple and city, in A. D. 70, fallen so near to decay, as to com- prise only a 200th part of the whole; that the third denomina- tion, viz. Christians, now include one-fourth part of the wholo; and that the Mahomcdans, who sprung up six centuries after the Christians, and threatened to annihilato them, occupy the space of one-sixth part of the whole. It is also observable, that when an estimate of this kind was made about ſiſty years since, it was supposod that Christians amounted to one-sixth part, and now they have increascd to one-fourth. A step fur- ther in this inquiry disposos of the Christians thus, in their subdivisions:– The Greek and Eastern Churches, ... . . . . . 30,000,000 Roman Catholics, . . . . . . . . . . . . . . . . . . . . 100,000,000 Protestants, including all sects,.......... 70,000,000 Total,. to e º & 0 tº tº e º e º 0 200,000,000 Hº () R. P O R. DICTIONARY OF MECHANIC AI, SCI EN (; E. 827. Those have all arison since the promoting of the Universal Christian Church, 4,000 A.M. of which— - The Western and Eastern Churches began and united in the . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6th Century. Their separation, . . . . . . . . . . . . . . . . . . . . . . . . . . 9th do. Mahomed, . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7th do. Christianity in Great Britain, . . . . . . . . . . . . . . . 7th do. Darkness of Popcry and Mahomedanism, .... 6th to 16th do. Waldenses, . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12th do. Wickliffe, Huss, and Jerome, . . . . . . . . . . . . . . . 13th to 15th do. Luther and Calvin, . . . . . . . . . . . . . . . . . . . . . . . . 16th do. Reformation, ... . . . . . . . . . . . . . . . . . . . . . . . . . . 16th do. Remonstrants, . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17th do. Protestant scCts, . 17th & 18th do. It is unnecessary to enlarge this scalc; the object is thus answered by shewing the divisions of people, and their deno- minations and dates, by which any person, conversant in such researches, will find occupation enough for his reflection upon the probable state of mankind during the ensuing half century, under the advantages of an unexampled improvemeut in cvery country and condition, both in arts, navigation, and commerce, domestic and universal : an enriched acquisition of every em- bellishment of intellect, literature, and the find arts; chemistry, and religious learning ; an enlarged and liberal toleration in Church and State; a diffusion most unparallclod of the Holy Scriptures, of cducation, and a gencral intercourso among all nations. In the lists of births and deaths in the kingdom of Bohemia, published for 1824, there is a considerable oxcess of births. In the capital, Prague, there were, out of 4436 deaths, 1633 of infants under a year old. The number of suicidos was 105, or about one in forty. In London, in 1821, there were but 82 suicides out of 18,458 deaths, within the limits of the bills of mortality, or one in 225. In 1822 there were only 33 suicides in the bills of mortality. In l'aris there were, in 1824, about 360 or 370, out of a population smaller than that of London: so false is the notion that we are, as compared with our neigh- bours, an ominently self-killing people. We arc, in truth, not above a quarter part as suicidal as the people of Paris, and not much more than a sixth part so than the people of Prague. POPULUS ALWA. (White Poplar.) This is a very ornamental trec. The leaves on the under surface are of a fine whito, and on the reverse of a very dark green ; and when growing on large trees are truly beautiful, as every breath of air changes the colour as the leaves move. The wood of all the species of pop- lar is useful for boards, or any other purpose, if kept dry. It is much in demand for floor boards for rooms, it not rcadily taking fire; a red-hot poker falling on a board, would burn its way through it, without causing more combustion than the hole through which it passod. PopULUs Monilifera. (Canada Poplar.) This is also known by the name of Black Italian Poplar, but from whence it had this name we do not know. This specios, which is the finest of all the kinds, grows very commonly in woods and hodges in many parts of Worcestershire and Herefordshire, where it reaches to prodigious sizes. Perhaps no timber is more uscful than this ; it is very durable, and easy to be converted to all purposes in building. The floors of a great part of Downton Castle, the seat of R. Payne Knight, Esq. are laid with this wood, which have been used forty years, and are perfoctly sound. Trces are now growing on his catate which aro three and four feet in diameter. PopUI.Us Nigra. (The Black Poplar.) Its Buds. The young buds or rudiments of the leaves, which appear in the beginning of spring, abound with a yellow, unotuous, odorous juice. They have hitherto been employed chiefly in an ointment, which received its name from them, though they are certainly capable of being applicq to other purposes; a tincture of them, made in rectifical spirit, yields upon being inspissated, a fragrant resin superior to many of those brought from abroad. PORCELAIN, a ſino sort of earthenware, chiefly manufac- tured in China, and thenco called china-ware. The combination of silex and argil is the basis of porcelain ; and, with the addi- tion of various proportions of other earths, and even of some metallic oxides, forms the different varieties of pottery, from the ſinest porcelain to the coarsest carthenware.—Though sili- cious earth is the ingredient which is present in largest propor- tion in these compounds, yet it is the argillaceous which more particularly gives thom their character, as it communicatcs duc- tility to the mixture when soft, and renders it capable of being turned into any shape on the lathc, and of being baked. The clays are native mixtures of these earths; but they are often rendered unfit for the manufacture of at least the finer kinds of porcelain, from other ingredients which they also contain. The perfection of porcelain will depend greatly on the purity of the earths of which it is composed; and hence the purest natural clays, or those consisting of silex and argil alone, are selected. Two substances have been transmitted to Burope as the mate- rials from which the Chinese porcclaim is formed , which have bc.cn named Kaolin and Petumse. It was found diſſcult to pro- cure, in Europe, natural clays equally pure, and hence in part the diſficulty of imitating tho porcelain of the East. Such clays, however, have now been discovered in different countries; and hence the superiority to which the European porcelain has attained. The fine Dresden porcclain, that of Berlin, the French porcelain, and the ſincr kinds which are formed in this country, are manufactured of such clay, which from the use to which it is applied, has received the name of porcelain earth, and which appears, in general, to be derived from the decomposition of felspar of granite. It appears also that matural earths, contain- ing magnesia, are used with advantage in the manufacture. The proportion of the earths to each other must likewise be of importance ; and from diſſerences in this respect arise, in part, the diſſerences in the porcelain of diſſerent countries, as well as the necessity frequently of employing mixtures of matural clays. The argil communicates tenacity and ductility to the paste, so that it may be oasily wrought ; the silex gives hardness and infusibility; and on the proper proportion of these depends, in a great measure, the perfection of the compound. The propor- tion of silex in porcclaim of a good quality, is at least two-thirds of the composition ; and of argil, from a fifth to a third. Mag- nesia is of utility, by lessening the tendency which the compo- sition of silox and argil alone has to contract in baking, which is inconvenient in the manufacture. Portcela 1N of 18eaumur.—Reaumur gave the quality of porcclaim to glass ; that is, he rendered glass of a milky colour semi-transparent, so hard as to strike ſire with steel, infusible, and of a ſibrous grain, by means of cementation. The process which he published, is not difficult. Common glass, such as that of which wine bottles are made, succeeds best. The glass vessel which is to be converted into porcelain is to be enclosed in a baked carthen case or seggar. The vessel and case are to be filled with a cement composed of cqual parts of sand and pow- dered gypsum or plaster, and the whole is to bo put into a potter's kiln, and to remain there during the baking of common earthonware ; after which the vessel will be found transformed into such a matter as has becrl describcd. PORE, in Anatomy, a little interstice or space between the parts of the skin serving for perspiration. Pores are small interstices between the particles of matter which compose bodies; and are cither cmpty, or filled with some insensible medium. Condensation and rarefaction are only performed by closing and opening the pores. PORIME, Poſtſ MA, in Gcomotry, a sort of lomma or theorem, so obvious or solf-evident as to differ but little from an axiom or self-evident proposition. . IPORISM, Poſtis MA, in Geometry, is a peculiar sort of pro- position, which has been differently defined by diſſerent writers, some considering it as a general theorem or canon, deduced from a geometrical locus, and serving for the solution of other general and diſficult problems; while others make it a lemma, or the same as porima. Dr. Simson deſines it a proposition, either in the form of a problem or a theorem, in which it is pro- |. cither to investigate or demonstrate. Euclid wrote three ooks of porisms, being a curious collection of various things relating to the analysis of the more difficult and general prob- lcms. Those books, however, are lost, and nothing remains in the works of the ancient geometricians, concerning this subject, besides what Pappus has preserved, in a very imperfect and obscure state, in his “Mathcmatical Collections,” viz, in the introduction to the seventh book. 828 P O R. P O R. DICTIONARY OF MECHANICAL SCIENCE. PORISTIC Method, in Mathematics, is that which deter- mines when, by what means, and how many different ways, a problem may be resolved. POROSITY, an essential property of bodies, is best ascer- tained by the microscope, which shews us the passage of fluids through solid bodies; or we may discover this property in the transmission of light in all directions through the internal structure of hard and solid bodies. The porosity of wood is very remarkable. Air may be blown by the mouth, in a pro- fuse stream, through a cylinder two feet long of dried oak, beech, elm, or birch; and if a piece of wood, or a piece of marble, be dipped in water, and submitted to experiment under the receiver of a pneumatic machine, the air issuing through the exterior cavities will appear in a torrent of bubbles on the . external surface. In like manner mercury is forced through a piece of dry wood, and made to fall in the form of a fine divided shower. If a few ounces be tied in a bag of sheep skin, it may be squeezed through the leather by the pressure of the hand, in numerous minute streamlets. This experiment illustrates the porosity of the human cuticle. From microscopic obser- vations, it has been computed that the skin is perforated by a thousand holes in the length of an inch. If we estimate the whole surface of the body of a middle-sized man to be sixteen square feet, it must contain no fewer than 2,304,000 pores. These pores are the mouths of so many excretory vessels, which perform that important function in the animal economy, insensible perspiration. The lungs discharge every minute six grains, and the surface of the skin from three to twenty grains, the average over the whole body being fifteen grains of lymph, consisting of water, with a very minute admixture of salt, acetic acid, and a trace of iron. If we suppose this perspirable matter to consist of globules only ten times smaller than the red particles of blood, or about the 5000th part of an inch in diameter, it would require a succession of 400 of them to issue from each orifice every second. The permeability of a solid body to any fluid, depends however on its peculiar structure and its relation to the fluid. A compact substance will some- times oppose the entrance of thin fluid, while it gives free pas- sage to a gross one. Thus, a cask, which holds water, will permit oil to ooze through it; and a fresh humid bladder, which is air-tight, will yet, when pressed under water, imbibe a notable portion of that liquid. If a cylindrical piece of oak, ash, elm, or other hard wood, cut in the direction of its fibres, be cemented to the end of a iong glass tube, water will pass freely through it, in divided streamlets; but a soft cork inserted into a similar tube will effectually prevent all escape of the liquid. Mercury may be carried in a small cambric bag, which could not retain water for a moment. If a circular bottom of close-grained wood, divided by a fine slit from the 30th to the 100th part of an inch wide, be cemented to the end of a glass tube, it will support a column of mercury from one to three or more inches high, the elevation being always proportional to the narrowness of the slit. Hence a cistern of box-wood is frequently used for portable barometers, the fine joints admit- ting the access and pressure of the air, but preventing the escape of the mercury. Yet a sufficient force would overcome this obstruction; and, in the same manner, the air which is confined in the common bellows under a moderate pressure, might, by a more violent action, be made to transpire copiously through the boards and the leather. The transmission of a fluid through a solid substance shews the existence of pores: but the resistance, in ordinary cases, to such a passage, is insufficient, therefore, to prove the contrary. The permeability of translucent substances to the rays of light, in all directions, evinces the most extreme porosity. But this inference is not confined merely to the bodies usually termed diaphanous; for the gradation towards opacity advances by insensible shades. The thin air itself. is not perfectly translucid, nor will the densest metal absolutely bar all passage of light. The whole mass of our atmosphere, equal to the weight of a column of thirty-four feet of water, transmits, according to its compara- tive clearness, only from four-fifths to three-fourths of the per- pendicular light, and consequently retains or absorbs from a fifth to a fourth of the whole. But this absorption is greatly increased by the accumulation of the medium. When the sun has approached within a degree of the horizon, and his rays quently of that colour. now traverse a tract of air equal in weight to a column of 905 feet of water, only the 212th part of them can reach the surface of the earth. By a peculiar application of my Photometer, I have found that half of the incident light, which might pass through a field of air of the ordinary density and 15% miles extent, would penetrate only to the depth of fifteen feet in the . clearest sea-water, which is therefore about 5400 times less diaphanous than the atmospheric medium. But water of shal- low lakes, though not apparently turbid, betrays a greater opacity, insomuch, that the perpendicular light is diminished one-half, in descending only through the space of six, or even two feet. The same measure of absorption would take place in the passage of light through the thickness of two or three inches of the finest glass, which is consequently 500,000 times more opaque than an equal bulk of air, and even 300 times more opaque than a corresponding mass of that fluid. But even gold itself is diaphanous. If a leaf of that metal, either pure or with only an 80th part of alloy, and therefore of a fine yellow lustre, but scarcely exceeding the 300,000th part of an inch in thickness, and enclosed between two thin plates of mica, be held immediately before the eye, and opposite to a window, it will transmit a soft green light, like the colour of the water of the sea, or of a clear lake of moderate depth. This glaucous tint is easily distinguished from the mere white light which passes through any visible holes or torn parts of the leaf. It is indeed the very colour which gold itself assumes, when poured liquid from the melting pot. A leaf of pale gold, or gold alloyed with silver, transmits an azure colour; from which we may, with great probability, infer, that if silver could be reduced to a sufficient degree of thinness, it would discharge a purple light. These noble metals, therefore, act upon white light exactly as air and water, absorbing the red and orange rays, which enter into its composition, but allowing the con- joined green and blue lays to effect their passage. If the yel. low leaf were estimated to transmit only the tenth part of the whole incident light, it would only follow, that pure gold is 250,000 times less diaphanous than pellucid glass. The inferior ductility of the other metals will not allow that fine lamination, which would be requisite for shewing, in ordinary cases, the transmission of light. But their diaphanous quality might be informed from the tints with which they affect the transmitted rays, on being alloyed with gold. Other substances, though commonly reckoned opaque, yet admit in various degrees the passage of light. The window of a small apartment being closed by a deal board, if a person within shut his eyes a few minutes to render them more acute, he will, on opening them again, easily discern a faint glimmer issuing through the win- dow. In proportion as the board is planed thinner, more light will be admitted, till the furniture of the room becomes visible. Writing paper transmits about a third part of the whole inci- dent light, and when oiled it often supplies the place of glass in the common workshops. The addition of oil does not, how- ever, materially augment the diaphanous quality of the paper, but renders its internal structure more regular, and more assi- milated to that of a liquid. The rays of light travel, without much obstruction, across several folds of paper, and even escape copiously through pasteboard. Combining these vari- ous facts, it follows that all bodies are permeable, though in extremely different degrees, to the afflux of light. They must therefore be widely perforated, and in every possible direction. The porosity of bodies is consequently so diffuse, that the bulk of their internal kernel, or of the ultimate obstacles which they present, may bear no sensible proportion to the space which they occupy. ..., FORPHY Rºy, derives its name from the Greek word sig- nifying red, as the porphyry used by the ancients was most fre- The term porphyry is very vague, being applied to all rocks that have a compact base or ground in which crystals of any kind are imbedded and distinctly visible. Thus, according to the kind of stone in which the crystals occur, the porphyry takes its more appropriate name, as horn stone porphyry, clay-stone porphyry, pitch-stone, and obsidian por- phyry, &c. The base of porphyry is generally allied to trap, and is fusible. The crystals are either quartz or felspar, but more commonly the latter, forming four-sided or six-sided prisms, whose length is greater than the breadth. . P O R. “ P O S. 829 DICTIONARY OF MECHANICAL SCIENCR. ... PORT, a harbour or haven on the sea-coast. Bar Port, is such as can only be entered with the tide. Close Port, is one within the body of a city, as the ports of Rhodes, of Venice, Amsterdam, Rochelle, Bayonne, and St. Jean de Luz. Free Port, is one open and free for merchants of all nations to load and unload their vessels in, without paying any duty or cus- toms; such are the ports of Genoa and Leghorn. Free Port, is also used for a total exemption and franchise which any set of merchants enjoy, for goods imported into a state, or those of the growth of the country exported. Such was the privilege the English enjoyed for several years after their discovery of the port of Archangel, and which was taken from them on account of the regicide in 1648. Port, is also a name given, on some occasions, to the lar- board or left side of the ship, as in the following instances:— The Ship Heels to Port, i.e. stoops or inclines to the larboard side. Top the Main yard to Port, the order to sway the lar- board extremity of that yard higher than the other. Port, is also used for the burden of a ship. - Port the Helm, the order to put the helm over to the lar- board side of the vessel, when going large. In all these cases, this word appears intended to prevent any mistakes happen- ing from the similarity of sounds in the words starboard and Harboard, particularly when they relate to the helm, where a misapprehension might be attended with very dangerous con- sequences: accordingly the word larboard is never used in conning. - Half Port, a kind of shutter, with a circular hole in the centre, large enough to go over the muzzle of the gun, and fur- nished with a piece of canvas, nailed round its edge, to tie upon the gun, whereby the water is prevented entering at the port, although the gun remains run out. . They are principally used upon the main-deck, and particularly in ships carrying one tier of cannon. Port Bars, strong pieces of oak, furnished with two lan- yards or ropes, by which the ports are secured from flying open in a gale of wind, the bar resting against the inside of the ship, and the port being firmly lashed to it by its two ring- bolts. - : Port- Last, or Portoise, is synonymous with Gunwale ; as, Lower the Yards a Port-last, that is, down to the gunwale. To Ride a Portoise, is to have the lower-yards and top-mast struck, or lowered down, when at anchor in a gale of wind. Port Lids, a sort of hanging doors, to shut in the ports at sea; they are fastened by hinges to the upper edges, so as to let down when the cannon are drawn into the ship, whereby the water is prevented entering the lower decks. They are more generally termed Ports. Port Ropes, ropes made fast to the outside of the portlids, and communicating with a tackle within, by which the portlids are occasionally drawn up. - Port Tackles, are those mentioned in the preceding article, as serving to haul up or open the ports. Port Holes, in a ship, are the holes in the side of the vessel through which are put the muzzle of the great guns. These are shut up in storms, to prevent the water from driving through them. - - w PORTA, John BAPTISTA, a Neapolitan, eminent for his learning. As he admitted a society of learned friends into his house, he was acused of magical incantations, and exposed to the censures of Rome. He died 1515, aged 70. He invented the camera obscura, improved afterwards by Gravesande, and formed the plan of an encyclopedia. He wrote a Latin treatise on natural magic, 8vo. ; another on physiognomy, mixed with astrology, &c. - - º PORTCULLIS, in Fortification, is an assemblage of several large pieces of wood, joined across one another like a harrow, and each pointed with iron at the bottom. They are sometimes hung over the gateway of old fortified towns, ready to let down in case of surprise, when the gates cannot be shut. PORTER, a kind of malt liquor which differs from ale and pale beer in being made of high-dried malt. - PORTGREVE, or Portgrave, anciently called the princi- pal magistrate in ports and other maritine towns. The word is formed from the Saxon “port,” and “geref” a governor. It is sometimes also written “portreve.” It is said by Camden, 85, that the chief magistrate of London was anciently called port- greve, which was exchanged by Richard I. for two baliffs; and these again gave place, in the reign of King John, to a mayor, who was an annually elected magistrate. - PORTLAND Stone, is a dull whitish species much used in buildings about London. It is composed of a coarse grit cemented together by an earthy spar. - PORTRAIT. See PAINTING. PORTS, the embrasures or openings in the side of a ship of war, wherein the artillery is ranged in battery upon the decks, above and below. Gun-room Ports, are situated in the ship's counter, and are used for stern-chases, and also for passing a small cable or a hawser out, either to moor, head and stern, or to spring upon the cable, &c. Lower-deck Ports, are those on the lowest gun-deck. Middle deck Ports, are those on the second or middle gun-deck of three-deckers. POSITION, or the Rule of False Position, otherwise called the Rule of Falsehood, in Arithmetic, is a rule so called because in calculating on several false numbers taken at random, as if they were the true ones, and from the differences found therein, the number sought is determined. The rule is either single or double.—Single Position, is when there happens in the propo- sitions some partition of numbers into parts proportional, in which case the question may be resolved at one operation, by this rule: Imagine a number at pleasure, and work there with according to the tenor of the question, as if they were the true number; and what proportion there is between the false con- clusion and the false proportion, such proportion the given number has to the number sought Therefore the number found by augmentation, shall be the first term of the rule of three ; the second number supposed, the second term ; and the given number, the third. Or the result is to be regulated by this proportion, viz. As the total arising from the error, to the true total, so is the supposed part to the true one. Ex- ample: A, B, and C, designing to buy a quantity of lead to the value of 140l. agree that B shall pay as much again as A ; and C as much again as B; what must each pay. Now suppose A to pay 10l. then B must pay 20t. and C 401, the total of which is 70l. but it should be 140l. Therefore, if 70l. should be 140l. what should 10l. be 2 Answer, 20l. for A's share, which doubled makes 40l. for B's share, and that again doubled, gives 80l. for C's share, the total of which is 140l.--Double Position, is when there can be no partition in the numbers to make a proportion. In this case, therefore, you must make a supposition twice, proceeding therein according to the tenor of the question. If neither of the supposed numbers solve the proportion, observe the errors, and whether they are greater or less than the sup- position requires, mark the errors accordingly with the sign + or —. Then multiply contrariwise the one position by the other error; and if the errors are both too great or both too little, subtract the one product from the other, and divide the differ- ence of the products by the difference of the errors. If the errors are unlike as the one + and the other —, add the products, and divide the sum thereof by the sum of the errors added toge- ther, for the proportion of the excesses or defects of the num- bers supposed to be the number sought; or the suppositions and their errors being placed as before, work by this propor- tion as a general rule, viz. as the difference of the errors if alike, or their sum if alike, to the difference of the suppositions, so either error, to a fourth number; which accordingly added to or subtracted from the supposition against it, will answer the question.—Such are the instructions commonly given in books of arithmetic on this subject; but it were certainly better to abandon all these rules, and solve questions of this stamp by means of equations and algebraic analysis. Thus, let us take the example before us, in single position, as it is called ; and Let a = A's share; 2 a. F B's share; 4a: = C's share ; then, by the question z + 2 x + 4 x = 140, or 7 x = 140 ..". 2 - * - £20 for A's share, which doubled makes £40 for B's share; and this last doubled gives £80 for C's sharo. Any person capable of handling an equation, may thus work out questions in position, without staring at the supposed wis- dom and ability of a poor pedagogue bringing out the answer by trials, . . 10 B 830 P O S F O S DICTIONARY OF MECHANICAL scIENCE. Evample. What number is that which, being multiplied by 6, the product increased by 18, and the sum divided by 9, the quotient shall be 20. Let the two supposed numbers be 18 and 30. Then 18 30 6 6 108 180 | S 18 9) 126 9) 198 smm mºsºms *=- 14 the 1st result. 22 the 2d result. mºsºmsºmºsºms *- Then 22 – 14 : 30 — 18 : : 20 – 14 Or, 8 : 12 : : G : 9, the correc- tion to 1st supposition; therefore 9 + 18 = 27, the number sought. By Algebra, - º a: X 6 + 18 then ***** = 20 by the question; i.e. a × 6 + 18 = 180, or 6a -- 18 = 180. By transposition, 6 a – 180 – 18 = 162, or 6 a. = 162, therefore 162 a – —- F 27. POSITION, in Astronomy, relates to the sphere. The posi- tion of the sphere is either right, parallel, or oblique; whence arisc the inequality of days, the difference of seasons, &c. Circles of Position, are circles passing through the common intersections of the horizon and meridian, and through any degree of the ecliptic, or the centre of any star, or other point in the heavens, used for finding out the position or situation of any star. These are usually counted six in number, cutting the equator into twelve equal parts, which the astrologers call the celestial houses. Centre of Position. See CENTRE. - Given in Position, in Geometry, is an expression made use of to denote that the position or direction of a line is given or known. - Geometry of Position, is a species of geometry first treated of by Carnot, the object of which is to investigate and deter- mine the relation that has place between the position of the different parts of a geometrical figure with regard to each other, or with regard to some determinate line or figure first fixed upon as a term of comparison, and which is called the primi- tive system, while that compared with it is denominated the transformed system; and as long as the different parts of the transformed system have the same directions or positions with regard to each other, their relation is said to be direct, but when they are diſſerent, inverse. POSITIVE Elect Ricity. In the Franklinian system, all bodies supposed to contain more than their natural quantity of electric matter, are said to be positively electrified; and those from whom some part of their electricity is supposed to be taken away, are said to be electrified negatively . These two electricities being first produced, one from glass, the other from amber or rosin, the former was called vitreous, the other resinous, electricity. Positive Quantities, in Algebra, are those which are aſſected with the sign + being affirmative or addative, in contradistinc- tion to negative quantities, which are to be subtracted. POSSESSION, is two-fold; actual, and in law. Actual pos- session, is when a man actually enters into Hands and tenements to him descended. Possession in law, is when the lands and tenements are descended to a man, and he has not as yet actually entered into them. Staundf. 198. * POST, a military station. Thus the detachments established in front of the army are termed out-posts ; the stations on the wings of the army are said to be posts of honour, as being the most conspicuous and most exposed. But in the operations of a campaign, a post properly signifies any spot of ground capable of lodging soldiers, or any situation, whether fortified or not, where a body of men may make a stand, and engage the enemy to advantage. The great advantages of good posts, in war, as well as the mode of securing them, are only learned by experience. Barbarous nations disdain the choice of posts, or Let a = the number sought ; at least are contented with such as immediately fall in their way, they trust solely or chiefly to strength and courage; and hence the fate of a kingdom may be decided by the event of a battle. But enlightened and experienced officers make the choice of posts a principal object of attention. The use of them is chiefly felt in a defensive war against an invading encray; as by car- rying on a war of posts in a country where this can be done to advantage, the most formidable army may be so harassed and reduced, that all its enterprises may be rendered abortive. In the choice of a post, the general rules to be attended to are, that it should be convenient for sending out parties to reconnoi- tre, surprise, or intercept the enemy; that if possible it may have some natural defence, as a wood, a river, or a morass, in front or flank, or at least that it be diſlicult of access, and sus- ceptible of speedy fortification; that it shall be so situated as to preserve a communication with the main army, and have covered places in the rear to favour a retreat ; that it may command a view of all the approaches to it, so that the encmy cannot advance unperceived and rest concealed, while the detachment stationed in the post are forced to remain under arms; that it is not commanded by any neighbouring heights ; and is proportioned in extent to the number of men who are to occupy and defend it. It is not to be expected that all these advantages will often be found united ; but those posts ought to be selected which oſſers the greatest number of them. - Post, a conveyance for letters or despatches. The present establishment of the general post-oſlice of Great Britain con- sists of a postmaster-general, to the duties of which station there have, for many years past, been two persons appointed, under the title of joint postmasters-general ; a secretary; upwards of 150 assistants and clerks for the head letter-office in London, under the direction of a superintending president of the inland- letter department; and a comptroller of the foreign-letter office. Near 600 deputy postmasters throughout the kingdom, act under one principal, and nine riding surveyors. There are also distinct offices and clerks, acting under an accountant-gene- ral and a receiver-general ; as well as a separate establishment for the two-penny, formerly the penny post, which, since the abolition of Mr. Palmer's appointment of surveyor and comp- troller-general, has been new-modelled and greatly improved in all its branches. There is likewise a post-master-general of Scotland, with a secretary, comptroller, surveyor, and a sepa- rate establishment of all the requisite officers and clerks at Edinburgh, acting under the orders of the joint postmasters-ge- neral in London. The annual expense of management is about 350,000l. and the gross produce exceeds 1,300,000l. a year. Post, Two Penny, a post established for the benefit of Lon- don and other parts adjacent, whereby any letter or small par- cel is speedily and safely conveyed to and from all places within the bills of mortality, or within ten miles of the city. It is now managed by the general post-office, and receiving houscs are established in most of the principal streets, for the more conve- nient transmission of letters. - - t Post, a particular mode of travelling. A person is said to travel post, in contradistinction to common journey travelling, when, in place of going on during his whole journey in the same vehicle, and with the same horses, he stops at diſſerent stages, to provide fresh horses or carriages, for the sake of greater convenience and expedition. As he thus uses the same mode of travelling that is employed for the common post, he is said to travel post, or in post, i. e. in the manner of a post. Post Disseisin, a writ for him that, having recovercol land or tenements by praecipe quod reddat, upon default of reddition, is again disseised by the former disseisor. ' ' ' . POSTEA, is the return of the proceedings by nisi prius into the court of Common Pleas after a verdict, and there aſter- wards recorded. Plowd. 21 1. - - POSTERN, in Fortification, is a small gate generally made in the angle of the flank of a bastion, or in that of the curtin, or near the orillon, descending into the ditch; by which the garrison may march in and out unperceived by the enemy, either to relieve the works or to make private sallies, &c. - POSTULATE, in Geometry, a demand or petition, or a sup- position so easy and self-evidently true, as needs no explana- tion or iflustration; differing from an axiom only in the manner in which it is put, viz. as a request, instead of an assertion. P O T p O T DICTION ARY OF M E(; HANI (; A. L SCIENCE. 831 POTASS. This alkali is commonly called the vegetable alkali, because it is obtained from the ashes of vegetables. It has been discovered by Sir H. Davy to consist of a metal which he calls potassium, and two portions of oxygen and water. In the fashionable nomenclature of the day, it is called the hydra- ted deutoxide of potassium. In the arts of life, and indeed even in scientific investigations, we are not so much concerned with potassium, as with this very common and useful alkali in the state in which we find it. Table of the saline product of one thousand lbs. of potass of the following vegetables:—Saline Products.—Stalks of Turkey wheat or maise, 198 lbs. ; stalks of sunflower, 349 lbs. ; vine branches, 162’6 lbs. ; elm, 166 lbs. ; box, 78 lbs. ; sallow, 102 lbs. ; oak, 111 lbs. ; aspen, 61 lbs. ; beech, 219 lbs. ; fir, 132 lbs. ; fern cut in August, 116 lbs. ; or 125, according to Wil- denheim ; wormwood, 748 lbs. ; fumitory, 360 lbs. ; heath, 115lbs. Wildenheim. In both cases a high-coloured liquor is sepa- rated, which is to be poured off; and the potash must be kept carefully secluded from air. A perfectly pure solution of potash will remain transparent on the addition of lime-water, shew no effervescence with diluted sulphuric acid, and not give any pre- cipitate on blowing air from the lungs through it by means of a tube. About 100 parts of pure potass are equivalent to 70 of concentrated sulphuric acid ; therefore a good alkalimeter may be made by having a graduated tube, which divided into 100 equal parts, let 70 be filled with acid and the rest with pure water. If the alkali be quite pure, it will require the whole liquid in the tube to saturate 100 of the alkali; but if less will be sufficient, such as 75 parts, then we know that there are only 75 per cent. pure alkali; and so on for any other proportion. POTASSIUM is the metallic basis of potass, and may be obtained by placing hydrate of potass between two discs of platinum connected with the extremities of a powerful voltaic apparatus, when it will undergo fusion, and the oxygen will be separated, and the metallic globules will appear at the negative surface. When newly cut, it is splendent like silver, but soon tarnishes in the air, on which account it must be kept in a phial in pure naphtha. When thrown into the water, it swims on the surface, burning with a beautiful red mixed with violet. It combines with oxygen in different proportions. POTATOES. The potatoe is the bulb that contains the largest quantity of soluble matter in its cells and vessels; and it is of most importance in its application as food. Potatoes in general afford from one-fifth to one-seventh their weight of dry starch. (Solanum Tuberosum, Linn.) Saintmarc's mode of Distilling from Potatoes.—The intention of Saintmarc is to distil alcohol from potatoes, and the subject of his improvement is described under two heads ; viz. the mode of preparing the potatoes, ready to be converted into wash, and the general arrangement of the apparatus for conducting the fermentation and distillation, so as to retain the natural flavour of the spirit, and at the same time economize the use of fuel. It is first proposed to wash the potatoes free from the earth which adheres to their skins, by placing them in a rotatory drum, formed by open rails or staves, which drum is immersed in a trough or other vessel filled with water. When thus cleansed, the potatoes are to be introduced into a mill, for the purpose of being ground to a pulp. The construction of the mill to be employed is rather peculiar; it consists of a box, as usual, containing a cylinder having ribs of iron set into the periphery of the cylinder, which ribs are to be notched, or formed on the outside into teeth like fine saws. Two pieces of wood at right angles, the one standing in a perpendicular, the other in a horizontal direction, are to be brought up against the cylinder on one side, and the potatoes, introduced from a hopper above, are let fall between the cylinder and the wood, when, by the rotation of the cylinder, at the rate of about four hundred revo- lutions per minute, the potatoes become ground to a pulp, which descends into a receptacle below, there being a wooden scraper behind the cylinder, in order to prevent the pulp from adhering. The perpendicular piece of wood is made to give way by means of a spring behind it, for the purpose of allowing the larger potatoes to come in contact with the cutting cylinder, and the horizontal piece of wood is adapted with screws, in order to keep it up constantly against the cylinder which wears away the wood as it revolves. - The pulp of the potatoes thus produced in the mill, is now to be mixed with a considerable quantity of water, sufficient to bring it into a liquid state; it is then strained through a sieve, and such portions of the potatoe as will not pass through the sieve are rejected as useless, and set apart for feeding animals. The liquor thus strained, is then to be poured into a sort of cullender, or vessel having many holes, which vessel is lined with a cloth ; and here the pulp is allowed to settle, and the water to drain away, leaving the substance of the potatoe in a cake at bottom. This cake is then laid out upon a plaster floor, that its moisture may be drawn out by absorption, and afterwards it is dried in a kiln, where it may be kept perfectly good for a very great length of time. s’ In commencing the process of distillation from the prepared potatoes, the cake must be first broken and dissolved, by mixing with hot water till it has assumed the consistency of cream. A quantity of this liquor is then placed in a vat, which may be supposed to be situated as shewn at a, fig. 1. This figure shews the whole range of apparatus in action, from the vat a, in which the pulp is first introduced previous to femren- tation, down to the worm where the distilled spirit is ulti- mately condensed. º | gº-ºº: º - *::::: - º ~ tº: ## =: g }, - -->9 : ºss'é tl * §§§ºt : ElTL TUI T * - sº- zºº, Let the quantity of potatoe pulp introduced into the vat a, be equal to about three hundred weight when in a dry state, but mixed in the vat with hot water, to about the consistency of cream, as before mentioned; let there be water poured into the vessel b, until it rises above six inches from the bottom, and into this water introduce twenty pounds of sulphuric acid, observing that the vessel, b, should have a lining of lead, to prevent the action of the acid upon the wood. The cock of the vat a is now to be opened, and the liquor contained therein allowed to flow into the vat, b, which is called the decomposing vessel. Another portion of the potatoe pulp may then be mixed in the vat, a, and ſet off into the vat, b, as before; and so on until the vat, b, is sufficiently full. The proportion of acid to the pulp, necessary for decomposing it, should be from two to three pounds of the former, to every hundred-weight of the latter. Steam is now to be sent into the vat b, through the pipe c, from a boiler, and by means of this steam the liquor in b, is made to boil, and is to be kept boiling for four or five hours. The steam which evaporates from the vat, b, is allowed to pass up a worm pipe in the tub, d, which by that means heats the water in the tub, so that none of the heat is lost, and hot water, may then be drawn from the tub, through a pipe, to supply the vat dº After the boiling in the decomposing vessel is complete, the liquor is let off into a third vat, e, which is called the saturating vessel. During the time that the liquor is flowing into this vessel, a quantity of lime and water, or chalk and water, is introduced, in order to neutralize the sulphuric acid : two OT three pounds of chalk is generally sufficient for one of acid, but the introduction of the chalk or lime must be continued as long as any effervescence arises from the liquor. º tº 3 & When the liquor has subsided in the saturating vessel, it is to be drawn of into the fermenting vat, f, where a quantity of yeast is added, to promote the fermentation. The temperature ôf this vessel is to be kept up to about ninety or one hundred degrees of Fahrenheit's thermometer, and the room in which the operation is going on, to eighty or eighty-five degrees, during the whole time of its fermenting, which usually takes fifteen or twenty days. To facilitate the fermentation, hydrogen gas is 832 - P O T. P o T DICTIONARY OF MECHANICAL science. proposed to be injected into the liquor, by means of a force pump through the pipeg, which has a number of small holes in the lower part of the pipe, branches from which are coiled about the bottom; but this injection need not be made when the car- bonic acid gas, which escapes, contains an excess of hydrogen. This mode of introducing hydrogen into the wash, may be ad- vantageously employed to facilitate fermentation, whenever liquor is intended for distillation. The sediment of the vat, e, should be stirred up, to prevent the loss of any saccharine mat- ter, and allowed to run into the fermenting vat, When the process of fermentation is complete, the liquor is to be run from the vat f, into the still, h, through the pipe, i, and is then to be operated upon in the usual way. The form of this still is, however, something different from those stills com- monly used ; it is without the usual hand, and it is here intended that the evaporation shall pass up the long tube, k, in doing which, it will become partially condensed, and run down again into the still ; but the more volatile or spirituous part will pass over the neck at top, and proceed down the pipe to the worm t, immersed in 'cold water, where it will become con- densed, and discharge itself at the extremity of the pipe into any vessel placed under it. - The produce of this first distillation is called low wine; it is therefore necessary to pass the liquor again through the still before it becomes a highly concentrated spirit. For this pur- pose it is to be carried to another still shewn at a, fig. 2. Here the operation of distilling is conducted in the ordinary way, and the spirituous vapour passing up the pipe, b, descends into the closed vessel c, which is cooled by a reservoir of cold water, in a trough, d, at top. Here the spirit boils, and as it rises passes up the pipe, e, and descends into a long cylindrical ves- sel, f. This vessel is immersed in a trough of cold water, and is divided by partitions into six compartments, having small bent pipes leading from one to the other. The heaviest portion of the spirit condenses in the first compartment, and the vola- tile part proceeds through the pipe to the next, where the second heaviest becomes condensed, and the lightest passes through all the compartments, and proceeds through the pipe, g, to the worm immersed in the tub, h, from whence it dis- charges itself into a suitable receiver. The spirit condensed in the cylindrical vessel, f, may be pas- sed through the small pipes at the bottom of each compartment into the long pipe, i, and from thence drawn off for rectification, or it may be passed from the long pipe into the closed vessel, c, and from thence through the pipe k to the still for further dis- tillation. - The specification concludes by stating, that the invention con- sists, first, in the process by which a spirituous liquor is obtained or extracted from potatoe; and, secondly, in the improved ar- rangement and construction of apparatus for eſſecting the pro- cesses of fermentation and distillation. [Inrolled Sept. 1824.] Another Method of obtaining Brandy from Potatoes is this:– The potatoes are put into a close wooden vessel, and there boiled by steam, which is communicated to them at a degree little above that of boiling water; after they are boiled or Steamed, they are reduced to a paste with extraordinary faci- lity, (which is done by machinery in the interior of the wooden vessel ;) they then add boiling water to the paste, and a little potash rendered caustic by quicklime; the addition of the alkali is to dissolve the vegetable albumen, which prevents the com- plete conversion of the potatoes into starch. The starch liquor, after being filtered and evaporated, gives a residue very pure, and susceptible of being treated chemically: we are then directed to draw off the brandy from the potatoes, which has the proper herbaceous taste: it is then mixed with chlorate of lime, by which process the brandy is rendered equal to that distilled from wine. It will be observed that there is some dif- ference between this process of obtaining spirits from potatoes, and that described in the immediately preceding article. - POTENTILLA ANs ERINA. (Silverweed.)—The sensible qua- lities of Anserina leaves promise no great virtue of any kind; for to the taste they discover only a slight roughness, from whence they were thought to be entitled to a place among the milder corroborants. As the astringency of tormentil is con- fined chieſly to its root, it might be thought that the same cir- cumstance would take place in this plant; but the root is found to have no other than a pleasant sweetish taste, like that of parsnip, but not so strong. - PotentillA Reptans. (Cinquefoil, or Five Leaved Grass.)— The root is moderately astringent; and, as such, is some- times given internally against diarrhoeas and other fluxes; and it is employed in gargarisms for strengthening the gums, &c. The cortical part of the root may be taken, in substance, to the quantity of a dram; the internal part is considerably weaker, and requires to be given in double the dose, to produce the same effect. It is scarcely otherwise made use of than as an ingre- dient in Venice treacle. - POTERIUM Sanguisorba. (BURNet.)—This plant grows in calcareous soils, and is in some places much esteemed. On the thin chalky soils near Alresford in Hampshire, I have observed it to thrive better than almost any other plant that is cultivated. Sheep are particularly fond of it, and I have heard it said that the flavour of the celebrated Lansdown mutton arises from the quantity of burnet growing there. It is also the favourite food of deer. This will grow well in a calcareous soil, and there are few pastures but would be benefited by its introduction. Twenty-five pounds per acre are sown alone; eight pounds, mixed with other seeds, would be sufficient to give a good plant on the ground. POTTERY, the art of making vessels from earth, is of the remotest antiquity. In the earlier ages of the world, almost all domestic utensils were of pottery, which may hence be fairly supposed the oldest of mechanical inventions. The Scriptures first mention the practice of this art. The numerous remains of Greek and Etruscan vases, prove that these nations were celebrated for their skill in pottery. The Greek vases in Sir William Hamilton's collection, deposited in the British Museum, are ornamented with truly elegant paintings, and their forms are equally simple and beautiful. Porcelain, (from the Portuguese word, porcelena, a cup,) the most perfect species of earthenware, is distinguished from the inferior kinds of pot- tery, which are opaque and of various colours, by its being white and semi-transparent. Europe has now excelled the Oriental nations in the art of making porcelain. Besides the manufactory of Saxony, which has been long established, porcelain is made at Vienna, at Frankendal, and lately in the neighbourhood of Berlin. In France, the Serres porcelain holds the most distinguished rank. Italy also has its porce- Iains, the best of which are those of Naples and Florence. The potteries of England have made rapid advances towards per- fection. The chief establishments are in Staffordshire, at Derby, Worcester, Coalport, and Liverpool. The Stafford- shire potteries have long been celebrated for their earthen- wares, and some of the principal proprietors have directed their attention to the manufacture of porcelain, which has attained a high degree of excellence. The earthenwares for- merly manufactured here were coarse; the finest sort was an imperfectly white ware, very slightly ornamented with blue, and glazed by throwing into the oven, while the ware was firing, a quantity of common salt; the salt was converted into vapours, and, applied to the surface of the vessels, formed the glazing. The colour of the body of this kind of ware is said to have received considerable improvement from the following incident: Mr. Astbury, a Staffordshire potter, travelling to London, per- ceiving something amiss with one of his horses’ eyes, a hostler at Dunstable offered to cure the animal, and for that purpose put a common black flint stone into the fire. When taken out, it was observed to be of a fine white: the potter immediately conceived the idea of improving his ware, by adding this P O T P O T DICTIONARY OF MECHANICAL SCIENCE. 833 material to the whitest clay he could obtain. He sent home a quantity of the flint stones, and, by mixing them with tobacco- pipe clay, produced a white stone warc superior to any that had been made before. The other potters followed his czam- ple.—in 1763, Wedgwood invented a species of earthenware new in its appearance, and covered with a rich and brilliant glaze, called quccn's warc. Hence may be dated a new aera in this interesting and important manufacture. Wedgwood's ware evinces considerable taste in the elegance of his antique models, and in the excellence of their execution. Spode's ware, or blue and white, in imitation of the Oricntal china, or porcelain, has been introduced with great success in various manufactories. The potteries in Staffordshire are not less than onc hundred in number; employing more than ten thousand persons; and the annual value of goods manufactured there, may be estimated, in the most flourishing times, at eight hun- dred thousand pounds sterling. A canal furnishes the manu- facturers with the means of water-carriage to cvery principal sca-port in the kingdom; greatly facilitating the exportation of the manufactured articles, and the importation of the raw material. The number of persons employed in Spode's esta- blishment amounts to more than seven hundred, and the latest discoveries in machincry are applied to the advancement of the art. We now proceed to describe the general processes pursued at. Spode's manuſactory, and which may be classed thus:– 1°reparations of the raw material—moulding and turning— firing—printing—glazing—and painting. In the preparation of the raw material, a powerful steam- cngine performs many of the processes formerly carried on by manual labour. The bodies of carthenware are composed of Kent flint and West of England clay. The ſlint is first calcined in kilns, similar to those in which lime is burnt; it is then broken by revolving hammers, put in motion by the steam- engine, and afterwards Conveyed into the pans, paved with stone, to be ground with water. In the centre of the pans there is an upright shaft, from which several transverse arms branch out, having very heavy stones placed between them; these stones, moved horizontally by the steam-engine, grind the flints, until they form a cream-like liquid, which is let off into the wash-tub, where the coarser particles are separated from the fine; the latter runs of into reservoirs, and the former is carried back to the grinding pan. When the ground ſlint is wanted for use, it is conveyed from the reservoir by a pump worked also by the steam-cngine. The process of preparing the clay, and mixing it with the flint, is this :—The clay is drawn up into the upper chamber of the slip-house, and there thrown into an iron box, in which moves a shaft, with knives fixed in it, to cut the lumps into small pieces. The clay is now laid in a cistern with a proper quantity of water, where it softens, and is then put into the plunging-tub; in this tub the water and clay are stirred until they become thoroughly mixed. The liquid is now drawn oſſ into another cistern, from which it passes through a silk sieve into a third cistern, then into a fourth, through silk sieves still finer, the ground ſlint and other ingredients are now brought and mixed together; and the whole passes through sieves of a greater degree of fineness, into a fifth cistern: in this is a pump that throws it into a trough for conveying it to the drying kiln. All these various operations are worked by the steam-engine, and there arc fourteen sieves in motion at one time. After the clay has been dried, it is taken from the kiln and laid together in large heaps, and before it is worked into the ves- sels for which it is destined, the air-bubbles are disengaged from it. This is done by a machine turned by the steam- engine; the machine is an iron box shaped like an inverted cone, with an upright shaft in its centre, to which are affixed knives to cut the clay which is put into the box, by their rota- tory motion; and, at the same time, so arranged, as to force it downwards to a square aperture at the bottom, it escapes through this in a sufficiently compressed state for the workmen, and is then cut into square pieces of a convenient size to be distributed in the manufactory. Near the steam-engine are work-shops for those branches of the trade which require the aid of machinery; and in this building there are eight throw- ing wheels, and twenty-ſive turning lathes. Underneath these shops are drying-houses, heated by steam, in which the ware is dried, previously to its going to the oven to be fired; above the work-shops is a single room capable of holding two hundred workmen. * - Moulding and Turning.—Tea-cups, saucers, basons, jugs, and such like vessels, receive their first shape from the hands of the throw.cr. who sits on a stool with a flat circular wooden wheel before him, moving horizontally on a pivot. This wheel is sct in motion by the steam-engine, and the workman can increase or diminish its velocity as there is occasion. Upon the centre of the wheel the operator throws a lump of clay, of the required size, and forms it into almost any shape with the utmost facility: it is then cut from the wheel by a wire, and taken to be dried, that it may acquire sufficient hardness to fit it for the next operation. By turning, the superfluous parts of the clay are taken oſſ, so as to render the article perfectly Smooth, and to give it the exact shape. The lathes on which the vessels are turned, are also put in motion by the steam-engine, and regulated as to speed by the turner himself. The principle of turning earthenware is very similar to that employed in wood-turning.—The vessels requiring handles and spouts, are taken to the handling room, and those which do not want this appendage, after having attained the requisite hardness, are Sent to the oven to be baked. The handles, made on a mould of plaster of Paris, are fixed to the vessel with a liquid mixture of the same material as the vessel itself. For the formation of various articles manufactured in all potteries, moulds made of plaster of Paris are necessary. The modeller forms the shape of the intended vessel out of a solid lump of clay, which after receiving his finishing touches, is handed to the person who makes the plaster mould from it. Plates and dishes are made from moulds of this kind, upon which the operator lays a piece of clay of the length, breadth, and thickness required; the mould and clay are then placed upon a wheel turning horizontally on a pivot, and the operator keeps peeling round with the left hand, and presses the clay to the shape of the mould with the other. The mould and dish together are then carried into a stove moderately heated, where it remains until sufficiently dried to separate. The plate or dish is then cut even at the edges, and in other respects finished: before they are baked, the dishes are laid flat upon plaster or stone flags that are quite level, in order that they may remain straight until they go to the oven to be fired. Tureens, vege- table dishes, and such articles, are also made in moulds, but require more time and care, being less simple in their form. Figures, ſlowers, and foliage in bas-relief, are also formed separately in moulds, and afterwards affixed to the vessel with diluted clay. . . Firing.—When the ware is ready for firing, it is placed in chay cases called saggars, which vary in size and shape accord- ing to the articles placed in them. The saggars are put into an oven, shaped like a bee-hive, with an opening at the top; there is also an opening at the side to admit the saggars, but this is closed before the fire is applied. Each saggar is luted to the other by a roll of soft fire-clay. This secures the ves- scls contained in them from dust, the fumes of the fires, and from the eſſects of the air when the oven is cooling. The fires which heat the oven are placed round it in proper receptacles, which communicate with the interior of the oven by flues, heating every part equally. This first firing gives a higher degree of heat, and is continued much longer than any suc- cessive firing; when once fired, the article is called biscuit. ware. The cream-coloured, or queen's-ware, is now carried to the dipping-house to receive its glazing ; that which is to be printed blue is taken to the printing-house. Printing.—The design is previously engraven on a copper- plate, and laid on a stone to warm. The colour (which has oxide of cobalt for its basis) is mixed with a preparation of oils, to fetch out the impression. This mixture is smeared over the surface of the plate, and again cleaned off, leaving the liquid in the engraving only. The paper used to take off the impression is made expressly for this purpose; it is damped, laid on the copper-plate, and passed between two iron-rollers, as in ordinary copper-plate printing. The design being trans- ferred to the paper, is laid immediately upon the ware, being rubbed on with a flannel. After remaining a short time, the 10 C 884 P. R. A. P O W, DICTIONARY OF MECHANICAL SCIENCE. ware is put into a tub of water, and the paper is separated from it with a sponge, leaving the design in the most perfect state. The ware is then dried, and taken to the oven to be burned ; during this operation, the oil which has been mixed with the colour in the printing is destroyed, and the oxide of cobalt more firmly attached to the ware: it is then glazed. Glazing.—The glaziers differ in their composition in all manu- factories; most, however, have oxide of lead for their basis. The ingredients being mixed with water, and well ground, the glaze is ready for use, in which the vessels are dipped. On drying, which takes place instantly, the water contained in the glaze being absorbed by the porosity of the vessel, it is covered with a fine white powder of a regular thickness; this, when fired, becomes vitreous, or assumes a glass-like appearance, and from its transparency, the blue pattern underneath is rendered perfectly visible. In the last firing, especial care is taken to keep one piece from touching the other, or the whole would fuse into one united mass. Great attention is also requisite in the firing, not to give too much or too little heat, either extreme being injurious ; the fireman in this, as in the other firing, draws out trial pieces from the oven, with an iron rod, to ascertain the proper degree of heat, - Painting.—The pieces of porcelain or earthenware to be enamelled and enriched by gilding are, after the first firing, dipped in a suitable glaze, and again submitted to the fire. They are then delivered to the painter or enameller. The colours used in enamel-painting are composed df metallic calxes, and fluxes suitable to each colour, separately and con- jointly, and of such a nature as to fuse them sufficiently for the glazing on which they are laid. Gold has also its flux, and is laid on as the other colours are. When the painting is com- pleted, the ware is placed in a furnace less in size, and different in construction, from that before noticed. Care is here neces- sary in the arrangement of the vessels, and great nicety is required in the degree and the continuation of the heat, which is not so intense as in the former firings. The colours, after this firing, put on a shining appearance, but the gold has an opaque yellow cast, and is burnished with a blood-stone, to give it the desired brilliancy. - The processes already detailed for the manufacture of earthenware, are applicable, in nearly every case, to that of porcelain. The composition of the bodies and glazes is, of course, different; and much greater care is necessary in every process, than is bestowed upon earthenware in general. Delft ware, so called because first made at Delft, in Holland, is a kind of pottery of baked earth, covered with a white glaz- ing, which gives it the appearance of porcelain. The basis of this pottery is clay mixed with a certain quantity of sand; the vessels are slightly baked, so that they resist a sudden appli- cation of heat; and they are, lastly, covered with an enamel or glaze, which is composed of common salt, sand ground fine, and the oxides of lead and tin. The latter gives a white opaque colour to the mass. The furnace and colours used for paint- ing this ware, are the same as those which have been noticed as employed for porcelain. See PortCELAIN. , POUNCE, gum sandarach pounded and sifted very fine, to rub on paper, in order to preserve it from sinking, and to make it more fit to write upon. Pounce is also a little heap of char- coal dust, enclosed in a piece of muslin or some other open stuff, to be passed over holes pricked in a work, in order to mark the lines or designs on paper, silk, &c. placed underneath ; which are to be afterwards finished with a pen and ink, a needle, or the like. POUND, an English weight of different denominations, as, Avoirdupois, Troy, Apothecaries, &c. The pound avoirdupois is 16 ounces of the same weight, but the other pounds are each equal to 12 ounces. The pound avoirdupois is to the pound troy as 5760 to 6999;, or nearly as 576 to 700. See Me Asu RES. - - Pound is also the highest denomination used by the English in their money accounts, being equal to 20 shillings. + POURSUIVANT, or PURsulv ANT, in Heraldry, the lowest order of officers at arms. The poursuivants are properly attend- ants on the heralds, when they marshal public ceremonies. POWDER CHESTs, annong sailors, certain small boxes charged with powder and old nails, &c, and fastened occa- sionally on the decks or sides of merchant-ships, when fur- nished with close-quarters, having a train of powder which communicates with the inner apartments, so as to be fired at pleasure to annoy the enemy. These chests are usually from 12 to 18 inches in length, and about 8 or 10 in breadth, having their outer or upper terminating in an edge. They are mailed to several places of the quarter-deck and bulk-head of the waist, having a train of powder which communicates with the inner apartments of the ship. POWER, in Arithmetic and Algebra, that which arises by the successive multiplication of any number or quantity into itself, the degree of the power being always denominated by the number of equal factors that are employed; thus, 2", 1st power of 2. 2 - e e º e s tº c e o e g º C G O e º e g º º a 2 × 2 = . . . . . . . . . . . . . . . . 2*, 3d power or square. 2 × 2 × 2 = . . . . . . . . . . 2*, 3d power or cube. 2 × 2 × 2 × 2 ... . . . . . 2", 4th power, &c. &c. So also, ; F . . . . . . . . . . . . . . . . . . . . . a ', 1st power. a × w = . . . . . . . . . . . . . . . wº, 2d power. a × a × a = . . . . . . . . . . a', 3d power. a × a × a × a . . . . . . . . a', 4th power, &c. &c. Hence it appears, that the index which denotes the degree of any power, is always equal to the number of factors from which that power arises; or one more than the number of operations. See Expo NENT and INvo LUTION. Power of the Hyperbola, is the fourth power of its conjugate 3.x:l S. - - Powe R, in Mechanics, denotes any force, whether of a man, a horse, a spring, the wind, water, &c. which being ap- plied to a machine tends to produce motion. Power is also used in Mechanics, for any of the six simple machines, viz. the lever, the balance, the screw, the wheel and axle, the wedge, and the pulley. . . Power of a Glass, in Optics, is by some used for the distance between the convexity and the solar focus. Power, in Law, is an authority which one man gives to an- other to act for him, and it is sometimes a reservation which a person makes in a conveyance for himself to do some acts, as to make leases or the like. 2 Lil. Abr. 339. Thus power of attorney, an instrument or deed whereby a person is authorized to act for another, either generally, or in a specific transaction. Power of the county, called the Posse Comitatus, contains the aid and attendance of all knights, gentlemen, yeomen, labourers, servants, apprentices, and all others above the age of fifteen years within the county. Power Loom. See Loo M, p. 596. - BOZZOLANA, in Natural History, is a kind of substance formed of volcanic ashes. When mixed with a small portion of lime it quickly hardens, and this induration takes place even under water. This singular property, of becoming petrified under water, renders it peculiarly valuable as a cement, in the erection of moles, and other buildings in maritime situations. PRACTICE, is an Arithmetical rule, principally employed in those questions in which the amount of a certain number of things is required, the price of each being given; being a more ready and expeditious method than Compound Multiplication, by which rule the same questions may always be resolved. PRActice, is commonly divided into several cases, which by some authors are so much multiplied, as to become very bur- densome to the memory, an inconvenience that more than counterbalances the advantages arising from this subdivision: in fact, the whole of the cases that are worth retaining, may be classed under the following heads:– - 1. When the price is less than a penny. 2. When the price is less than a shilling. 3. When the price is less than a pound. 4. When the price is more than a pound. And the general rule for all these cases is this:– Rule. Take such aliquot parts of the given number of things, as the given price is of the next superior denomination.--Note. In the last case, multiply first by the number of pounds; and for shillings, pence, and farthings, proceed by the above rule, and add the result to the preceding product. T . . P. R. E. P R E DICTIONARY OF MECHANICAL SCIENCE. 835 *. Examples. #d. = 4643 at #d. 4d. : # 5648 at 43d. ad. = | |2321, #d. = } | 1882 8 . 1160; #d. E 3 || 235 4 117 8 12 || 3482% - - • 2,0 223,58 2,0 29,024 *= * £.14 10 24 Ans. - — 5s. = + 14186 at 6s. 7d. 6s. 8d. = 7416 at 8.6s. 8d. —— 3 ls. = } | 1046 10 6d. - % 209 6 22248 1%d. = } | 104 13 2472 26 3 3 £.24720 Ans. £. 1386 12 3 Ams. The same method may be employed in weights and measures of every description, though the rule is generally limited to money concerns. l t PRAECIPE, a writ commanding the defendant to do the thing required, or to shew cause why he hath not done it. PRAEMUNIRE. This punishment is inflicted upon him who denies the king's supremacy the second time; upon him who ro p y - affirms the authority of the pope, or refuses to take the oath of supremacy; upon such as are seditious talkers of the inherit- ance of the crown ; and upon such as affirm that there is any obligation by any oath, covenant, or engagement whatsoever, to endeavour a change of government either in church or state, or that both or either house of parliament have or has a legis- lative power, without the king, &c. The judgment in praemu- mire at the suit of the king, against the defendant being in prison, is, that he shall be out of the king’s protection; that his lands and tenements, goods and chattels, shall be forfeited to the king; and that his body shall remain in prison at the king’s pleasure ; but if the defendant is condemned upon his default of not ap- pearing, whether at the suit of the king or party, the same judgment shall be given as to the being out of the king’s pro- tection and the forfeiture; but instead of the clause that the body shall remain in prison, there shall be an award of a capi- atur. Co. Lit. 129. Upon an indictment of a praemunire, a peer of the realm shall not be tried by his peers. 12 Co. 92. PRAGMATIC SANction, in the Civil Law, is defined to be a rescript, or answer of the sovereign, delivered by advice of his council, to some college, order, or body of people, upon con- sulting him in some case of their community. The like answer given to any particular person, is called simply rescript. PRAM, or PRA Me, a sort of lighter used in Holland and the ports of the Baltic sea, for loading and unloading ships. PRATIC, or PRAtique, a term used in the European ports of the Mediterranean sea, which implies the permission to trade and communicate with the natives of any place, after having performed the required quarantine. PRAYER, in Theology, a petition put up to God for the obtaining of some future favour. \ PREBEN DARY, an ecclesiastic who enjoys a prebend. The difference between a prebendary and a canon is, that the former receives his prebend in consideration of his officiating in the church; but the latter merely by his being received into the cathedral or college. PRECEDENCE, or PREced excy, a place of honour to which a person is entitled; this is either of courtesy or of right. The former is that which is due to age, estate, &c. which is regu- lated by custom and civility: the latter is settled by authority, and when broken in upon gives an action at law. PRECEPT, in Law, a command in writing sent by a chief justice, justice of the peace, &c. for, bringing a person, record, or other matter, before him. * - PRECEPT, is also used for the command or incitement by which One man stirs up another man to commit felony, theft, &c. PRECESSION of the Equinoxes, which denotes that slow and imperceptible motion by which the equinoxes change their places, going backwards, or westward, contrary to the rest of the signs, may be thus explained. The fixed stars vary their right ascension and declination, but keep the same latitude; these variations are accounted for by supposing that the celes. tial sphere revolves round the pole of the ecliptic. Or, that the poles of the equator revolve round those of the ecliptic. And this revolution is called the precession of the equinoxes, because by it, the time and place of the sun’s equinoxial station pre- cedes the usual calculations. The ecliptic, the solstices, the | equinoxes, and all the points of the ecliptic, are moving from Aries towards Pisces; i. e. from east to west. The equinoctial | points are thence carried further back among the preceding signs or stars, at the rate of about one degree in 71 years and some few days. The annual precession is about 50' + ; that is, if the celestial equator cuts the ecliptic in a particular point on any day of this year, it will, on the same day of the following | year, cut in a point 50" + to the west of its former intersection, | and the sun will come to the equinox 20' 23" before he has com- | pleted his revolution of the heavens. Thus the equinoctial or | tropical year, or true year of the seasons, is so much shorter than the revolution of the sun, or the sidereal year. The equi- noctial points make a complete revolution in about 25,579 years, the equator being all the while inclined to the ecliptic in nearly the same angle. Therefore the poles of the diurnal revolution must describe a circle round the poles of the ecliptic at the dis- tance of nearly 233 degrees in 25,579 years. Hence the longi- tude, right ascension, and declination, of every star will be variable, and consequently the pole of the equinoctial cannot always be directed to the same star. In the time of Hippar- chus the equinoctial points were fixed to the first stars of Aries and Libra; and the stars which were then in conjunction with the sun when he was in the equinox, are now a whole sign to the eastward of Aries. There are obviously then two zodiacs, a zodiac of the signs, moveable round the fixed zodiac and eclip- tic. The precession of the equinoxes producing an annual increase of 50” # in the longitude of the fixed stars, makes exactly a degree in 71 years, 19'days, and 12 hours. Their right ascension varies from —60" to + 143" in certain stars round the pole. The annual increase in right ascension of others has been given as low as 5", or about 15' in 180 years. Their declina- tions vary from 20" to 0' annually plus or minus, or in 72 years from 24 minutes to 2 24" plus or minus. Astronomers have reckoned by the fixed and intellectual zodiac from a very early period ; the Egyptians and Chaldeans reckoned according to the intellectual zodiac ages before Hip- parchus made his discovery of the precession of the equinoxes. The first of their signs was Taurus. Hipparchus was the first among the Greeks, however, who established what is called a fixed zodiac ; and he placed Aries at the first of the signs. This shews that the Greeks were in the habit of copying from the Egyptians in these matters; for the ram has nothing to do with Grecian mythology; on the contrary, it was the type of the Egyptian Ammon. In the Egyptian zodiac, by the second Her- mes, Aries is represented as a man with ram's horns. The sun in this sign was worshipped as the god Ammon. This reces- sion of Aries from the equinoctial point, and its occupation by Pisces has furnished some learned men with curious illustrations respecting the origin of the zodiacal signs, the mythology of the Greeks, the Egyptians, and Orientalists: In 365d. 6h. 49mi. the earth revolves round the sun, and during its progress in this annual course, it passes through the 12 signs of the zodiac suc- cessively. Hence we are accustomed to say the sun is in Aries, Taurus, &c. when in fact it is the earth that is in those signs, | and the sun, as viewed from the earth, appears in the opposite part of its orbit. To find the Precession in right Ascension and Declination.— Put di- the declination of a star, and a ~ its right ascension; then their annual variations, or precessions, will be nearly as fol. low, viz. 20"-084 × cos. a = the annual precession in declination, and 46"-0619 + 20"-084 × sin. a X tang. d = that of right ascension. See the Connoissance des Temps for 1792, p. 206. PRECIPITATE. When a body, dissolved in a fluid, is either in whole or in part made to separate and fall down in the con- crete state, this falling down is called precipitation, and the matter thus separated is called a precipitate. 836 P R E P R E DICTIONARY OF MECHANICAL scIENCE. PREDIAL TITHEs, those which are paid of things arising and growing from the ground only, as corn, hay, fruit of trees, and the like. - | PREDICATE, in Logic, that part of a proposition which affirms or denies something of the subject; thus, in these pro- positions, snow is white, ink is not white, -whiteness is the predicate which is affirmed of snow, and denied of ink. PREGNANCY, to be with child. This is a plea in stay of execution, when a woman is convicted of a capital crime, alleg- ing that she is with child; in which case the judge must direct a jury of twelve discreet women to inquire of the fact; and if they bring in their verdict “quick with child,” execution shall be staid generally, until either she is delivered, or proves by the course of nature not to have been with child. 4 Black. 395. PREMISES, is that part of the beginning of a deed, the office of which is to express the grantor and grantee, and the land or thing granted. - PREROGATIVE, is a word of large extent, including all the rights and privileges which by law the king has as chief of the commonwealth, and as intrusted with the execution of the laws. PRERog Ative Court, the court wherein all wills are proved, and all administrations taken which belong to the archbishop by his prerogative ; that is, in case where the deceased has goods of any considerable value out of the diocese wherein he died; and that value is ordinarily 5l. except it is otherwise by composition between the said archbishop and some other bishop, as in the diocese of London it is 10l. PRESBYTERIANS, a numerous and highly respectable sect of Protestants, so called from their maintaining that the government of the church appointed in the New Testament was by Presbyteries; that is, by ministers and ruling elders, associated for its government and discipline. PRESENTATION, in Law, the act of a patron offering his clerk to be instituted in a benefice of his gift, the same being void. PRESENTMENT of OFFENCEs, is that which the grand jury find to their own knowledge, and present to the court without any bill of indictment laid before them at the suit of the king; as, a presentment of a nuisance, a libel, and the like, upon which the officer of the court must afterwards frame an edictment before the party presented can be put to answer it. There are also presentments by justices of the peace, con- stables, surveyors of the highways, church-wardens, &c. PRESIDENT, an officer created or elected to preside over a company, in contradistinction to the other members, who are called residents. PRESS, a machine of wood or iron serving to squeeze any body very close. Presses usually consist of six pieces: two flat smooth planks, between which the things to be pressed are laid ; two screws or worms fastened to the lower plank, and passing through two holes in the upper; and two nuts in the form of an S, that -serve to drive the upper plank, which is moveable, against the lower, which is fixed. See BRAMAH's MACHINE. - PR esses used for expressing Liquors, are in most respects the same with the common presses, only the under plank is perfo- rated with a great number of holes, for the juice to run through. Others have only one screw or arbor passing through the middle of the moveable plank, which descends into a kind of square box full of holes, through which the juices flow as the arbor is turned. - . PRess used by Joiners, to keep close the pannels, &c. of wain- scot, consists of two screws and two pieces of wood, four or five inches square, and two or three feet long, whereof the holes at two ends serve for nuts to the screws. - Founders’ PR ess, is a strong square frame consisting of four pieces of wood firmly joined together with tenons, &c. It is of various sizes; two of them are required to each mould, at the two extremes whereof they are placed : so as that, by driving wooden wedges between the mould and sides of the press, the two parts of the mould for the metal may be pressed close together. - PREss, Binder's Cutting, is a machine used equally by book- binders, stationers, and pasteboard-makers; consisting of two large pieces of wood in form of cheeks, connected by two strong wooden screws; which, being turned by an iron bar, draw together or set asunder the cheeks, as much as is neces- sary for the putting in the books or paper to be cut. The cheeks are placed lengthwise on a wooden stand in form a chest, into which the cuttings fall. Aside of the cheeks are two pieces of wood of the same length with the screws, serving to direct the cheeks, and prevent their opening unequally. Upon the cheeks the plough moves, to which the cutting knife is fastened by a screw; which has its key to dismount it, on occasion, to be sharp- ened. The plough consists of several parts; among the rest a wooden screw or worm, which catching within the nuts of the two feet that sustain it on the cheeks, brings the knife to the book or paper which is fastened in the press between two boards. This screw, which is pretty long, has two directories, which resemble those of the screws of the press. To make the plough slide square and even on the cheeks, so that the knife may make an equal paring, that foot of the plough where the knife is not fixed slides in a kind of groove, fastened along one of the cheeks. Lastly, the knife is a piece of steel, six or seven inches long, flat, thin, and sharp, terminating at one end in a point, like that of a sword, and at the other in a square form, which serves to fasten it to the plough. As the long knives used by us in the cutting of books or papers are apt to jump in the cutting thick books, the Dutch are said to use circular knives with an edge all round; which not only cut more stea- dily, but last longer without grinding. - PRESS, Packing. A very ingenious and useful packing press, invented by Mr. John Peck, procured for him in 1798, a reward from the Society of Arts. This machine consists of two very strong horizontal beams, one at the bottom for the bed, and the other at the top of the press. These are united by two iron screws, which stand in a vertical position, and therefore serve as cheeks to the press. The follower of this press is a very strong horizontal beam, having two nuts fitted into it at its ends. These nuts act upon the threads of the two vertical screws, and therefore it is plain, when they are turned round, that the follower will rise and fall accordingly. The nuts are so fitted into the follower, as to admit of a circular motion round the screw, but are not permitted to rise or fall without the follower. To give them motion, the edges of the circular rings are cut into cogs or teeth, and are turned by means of an endless screw for each, situated at the opposite ends of the horizontal spindle, which revolves in bearings attached to the follower of the press. The spindle has a winch at each end, by turning which the two endless screws act upon the wheels or teeth Öf the nuts, and by thus causing them to turn round with equal velocities, raises or depresses the follower always parallel to itself, and also to the head and bottom bed. The great utility of this press consists in its being capable of pack- ing two sets of bales at once, thus answering the purpose of two presses, with more expedition, and iess room. It is placed on the floor of the warehouse, and behind it a stage is erected, just half the height of the whole press. One set of bales is then made up on the floor, and the other upon the stage. Sup- pose the follower raised up above the level of the stage, a bale of goods is then placed on the lower bed, and by turning the winches the follower is forced down upon it, and remains there, till it is sufficiently pressed. While the men are tying up this bale below, others on the stage are loading the follower, and the winches being turned, the former bale is released, and the latter receives the pressure. By these means, no time is lost in screwing up or opening the press, since it performs work in both ways.—The Philosophical Transactions for 1781, contains an account of a double screw applied to a press by Mr. W. Hunter. Its power is considerable, but a minute description will occupy too much of our room. PREss, Copperplate Printing. In addition to the presses already noticed, although many others, adapted to particular purposes, are in use, the copperplate printing press demands a distinct description. This machine, of which a representation is given in the following figure, consists, like the common printing presses, (for which see PRINTING,) of a body and a carriage. The body consists of two cheeks, PP, of different dimen- sions, ordinarily about four feet and a half high, a foot thick, and two and a half apart, joined at top and bottom by cross pieces. The cheeks are placed perpendicularly on a wooden P R. E. P R. E 837 D1GTIONARY OF MECHANICAL science. stand or foot, L. M., horizontally placed, and sustaining the whole press. From the foot likewise rise four other perpendi- cular pieces, c, c, c, c, joined by other cross or horizontal ones, tl, d, d, which may be considered as the carriage of the press, as serving to sustain a smooth, even plank, HI K, about 4; feet long, 25 feet broad, and 13 inch thick; upon which the engraven plate is to be placed. Into the cheeks go two woodcrl cylinders or rollers D E, FG, about six inches in diameter, borne up at each end by the cheeks, whose ends, which are lessened to about two inches diameter, and called trunnions, turn in the cheeks between two pieces of wood, in form of half moons, lined with polished iron, to facilitate the motion. The space in the half moons, left vacant by the trunnion, is filled with paper, pasteboard, &c. that they may be raised and lowered at discretion ; so as only to leave the space between them necessary for the passage of the plank charged with the plate, | N Aft Nº. - =º g *N. º- Lº! Nº. j *N. º lºº paper, and blankets. Lastly, to one of the trunnions of the upper roller is fastened a cross, consisting of two levers AB, or pieces of wood, traversing each other. The arms of this serve in lieu of the handle of the common press, giving a motion to the upper roller, and that to the under one ; by which means the plank is protruded, or passed between them. The practice of printing from copper-plates is nearly as fol- lows:—The workmen take a small quantity of the ink on a rub- ber made of woollen rags, strongly bound about each other, and with this smear the whole face of the plate as it lies on a grate heated by a charcoal fire, or steam. The plate being sufficiently inked, they first wipe it over with a foul rag, then with a cleaner one, and lastly with the palm of their left and right hand, and to dry the hand and forward the wiping, they rub it from time to time on whiting. The address of the workman consists in wiping the plate perfectly clean, without taking the ink out of the engrav- ing. The plate thus prepared is laid on the plank of the press; over the plate is laid on the paper, first well-moistened to receive the impression; and over the paper two or three folds of flannel. Things being thus disposed, the arms of the cross are pulled, and by that means the plate, with its furniture, is passed through between the rollers, which pinching very strong- ly, yet equally, presses the moistened paper into the strokes of the engraving, whence it takes out the ink; and receives the engraved impression. Perkins' Copperplate Presses.—The press for which this cele- brated engineer and artist has obtained a patent, diſſers not in principle from that already described, although it varies con- siderably in several particulars. The levers or spokes, instead of extending from the pinion of the roller to the hand of the pressman, terminate in an iron circumference, which forms a wheel, on the outer surface of which numerous handles are inserted, resembling those fixed in the wheels by which ships are steered. By these means, when the wheel is put in motion, the momentum obtained, renders the resistance which the roller receives while passing over the plate almost imperceptible. The roller, having a section cut off longitudinally, performs its work with the circular part only, on which account the limits of the impression must always be determined by the extent of 86. its convexity. Unless, therefore, the roller be made very large, this press is better adapted for small plates than large ones. The plate having received its ink and paper, is presented to the roller, which, by turning the wheel, begins its work at the commencement of its convex surface, and passes on until the flat part turns downward. At this instant the impression ceases, the blanket which had been drawn in between the paper on the plate, and the roller, regains its original state of ten- sion, the plate is released, and returns on its carriage to the workman, delivering up its paper, and is ready to be charged for another impressiou. It must be obvious from hence, that the paper never receives from the press a double impression, but is taken off like proof prints in the common way. PRESS of SAIL, signifies as much sail as the then state of the wind, &c. will permit a ship to carry. PRESSED-MAN, one who has been impressed into the king’s service, in contradistinction to a volunteer. PRESS-GANG, a detachment of seamen, who (under the command of a lieutenant) are empowered, in time of war, to take any seafaring men, and oblige them to serve on board the king’s ships. PRESSING, in the Manufactures, is the violently squeezing a cloth, stuff, &c. to render it glossy. PRESSURE ENGINEs, for raising water by the pressure and descent of a column enclosed in a pipe, have been ſately erected in diſſerent parts of this country. The principle now adverted to, was adopted in some machinery constructed in France about 1731, (see Belidor de Arch. Hydraul, lib. 4. ch. 1.) and was likewise adopted in Cornwall about fifty years ago. But the pressure-engine, of which we are about to give a par- ticular description, is the invention of Mr. R. Trevithack, who probably was not aware that any thing at all similar had been attempted before. This engine, a section of which, on a scale of a quarter of an inch to a foot, as shewn in the annexed figure, was erected a few years ago at the I) ruid Copper Mine, in the parish of Illogan, near Truro. A 13 repre- sents a pipe six inches in diameter, through which water descends from the head to the place of its delivery, to run off by an adit at S, through a fall of 34 fa- thoms in the whole ; that is to say, in a close pipe, down the slope of a hill 200 fathoms long, with 26 fathoms fall; then perpendicularly six fathoms, till it ar- rives at B, and thence through the engine from 18 to S two fathoms. At the turn B the watcr enters into a chamber C, the lower part of which terminates in two brass cylinders, four inches in diameter; in which two plugs, or pis- tons of lead, D and E, - are capable of moving up and down by their piston rods, which pass through a close packing above, and are attached to the extremities of a chain ieading over, and properly attached to the wheel Q, so that it cannot slip. • * * g . . The leaden pieces D and E are cast in their places, and have no packing whatever. They move very easily; and, if at any time they should become loose, they may be spread out by a few blows with a proper instrument, without taking them out of their place. On the sides of the two brass cylinders, in which D and E move, there are square holes communicating. towards F and G, which is a horizontal trunk or square pipe, four 10 D * N P R E P R. E. DICTIONARY OF MECHANICAL scIENCE. inches wide and three inches deep. All the other pipes G, G, and R, are six inches in diameter, except the principal cylinder wherein the piston H moves; and this cylinder is ten inches in diameter, and admits a nine-feet stroke, though it is here delineated as if the stroke were only three feet. . . - The piston rod works through a stuffing-box above, and is attached to MN, which is the pit rod, or a perpendicular piece divided into two, so as to allow its alternate motion up and down, and leave a space between, without touching the fixed apparatus, or great cylinder. The pit rod is prolonged down into the mine, where it is , employed to work the pumps, or if the engine were applied to millwork, or any other use, this rod would form the communication of the first mover. K L is a tumbler, or tumbling-bob, capable of being moved on the gudgeons V, from its present position to another, in which the weight L shall hang over with the same inclination on the oppo- site side of the perpendicular, and consequently the end K will then be as much elevated as it is now depressed. The pipe R S has its lower end immersed in a cistern, by which means it delivers its water without the possibility of the external air introducing itself; so that it constitutes a torricellian column, or water barometer, and renders the whole column from A to S eſſectual; as we shall see in our view of the operation. The Operation.—Let us suppose the lower bar K V of the tumbler to be horizontal, and the rod PO so situated, as that the plugs or leaden pistons D and E shall lie opposite to each other, and stop the waterways C and F. In this state of the engine, though each of these pistons is pressed by a force equivalent to more than a thousand pounds, they will remain motionless, because these actions being contrary to each other, they are constantly in equilibrio. The great piston H being here shewn, as at the bottom of its cylinder, the tumbler is to be thrown by hand into the position here delineated. Its action upon OP, and consequently upon the wheel Q, draws up the plug D, and depresses E, so that the water-way G becomes open from A B, and that of F to the pipe R ; the water conseqmently descends from A to C ; thence to G G G, until it acts beneath the piston H. This pressure raises the piston, and if there be any water above the piston, it causes it to rise and pass through F into R. During the rise of the piston (which carries, the pit rod M N along with it,) a sliding block of wood I, fixed to this rod, is brought into contact with the tail K of the tumbler, and raises it to the horizontal position, beyond which it oversets by the acquired motion of the weight L. tº 8 tº The mere rise of the piston, if there were no additional motion in the tumbler, would only bring the two plugs D and E to the position of rest, namely, to close G and F, and then the engine would stop; but the fall of the tumbler carries the plug D downwards quite clear of the hole F, and the other plug E upwards, quite clear of the hole G. These motions require no consumption of power, because the plugs are in equilibrio, as was just observed. In this new situation, the column A B no longer communicates with G, but acts through F. upon the upper part of the piston H, and depresses it; while the contents of the great cylinder beneath that piston are driven out through G G G, and pass through the opening at E into R. It may be observed, that the column which acts against the piston is assisted by the pressure of the atmosphere, rendered active by the column of water hanging in R, to which that assisting pres- sure is equivalent, as has already been noticed. When the piston has descended through a certain length, the slide or block at T, upon the piston rod, applies against the tail K of the tumbler, which it depresses, and again oversets; producing once more the position of the plugs DE, here deli- meated, and the consequent ascent of the great piston H, as before described. The ascent produces its former effect on the tumbler and plugs; and in this manner it is evident, that the alterations will go on without limit; or until the manager shall think fit to place the tumbler and plugs DE in the positions of rest; namely, so as to stop the passages F and G. . The length of the stroke may be varied by altering the position of the pieces T and I, which will shorten the stroke the nearer they are together; as in that case, they will sooner alternate upon the tail K. As the sudden stoppage of the descent of the column A B, at the instant when the two plugs were both in the waterway, might jar and shake the apparatus, those plugs are º made half an inch shorter than the depth of thc side bioles; so that in that case, the water can escape directly through both the small cylinders to it. This gives a moment of time for the generation of the contrary motion in the piston and the water in G G G, and greatly deadens the concussion, which might else be produced. - - • * : * * Some former attempts to make pressure engines upon the principle of the steam-engine, haye failed ; because water, not being elastic, could not be made to carry the piston onwards a little, so as completely to shut one set of valves and open another. In the present judicious construction, the tumbler performs the office of the expansive force of steam at the end of the stroke. . - $. • Mr. Boswell suggests, as a considerable improvement, that the action of this engine should be made elastic by the addition of an air-chamber, on the same principle as that used in fire- engines; this, he thinks, might be best effected by making the piston hollow, with a small orifice in the bottom, and of a larger size, to serve for this purpose, as the spring of the air would then act both on the upward and downward pressure of the Water. . d PRESSURE, in Physics, is properly the action of a body, which makes a continual effort or endeavour to move another body on which it rests; such as the action of a heavy body supported by a horizontal table, and is thus distinguished from percus- sion or momentary force of action. Since action and reaction are equal and contrary, it is obvious that pressure equally relates to both bodies, viz. the one which presses, and that which receives the pressure. See a few remarks on the dif- ference between percussion and pressure, under the article PERCUSSION. . - PRESSURE of Fluids, is of two kinds, viz. of elastic and non- elastic ſluids. PR essure of Non-elastic Fluids. The upper surface of a homogeneous heavy fluid in any vessel, or any system of com- municating vessels, is horizontal. Fig. 1. This is a matter of universal experience; and, as it is easily ob- served, may be taken for the distinguishing property of fluids. Thus, if A B C D EF, fig. 1, be a vessel in which the branches. C D H, EFG, have a free communication with the part A B ; then if water, or mer- cury, or wine, or any other, fluid commonly reckoned non-elastic, be poured in either at A, C, or E, and when the whole is at rest, - - - the surface of the fluid stands at IK in the larger trunk; if the line L I K M be drawn parallel to the horizon, the surface of the fluid will stand at L in the branch E F, and at M in the branch C D ; and this what- ever are the inclinations of those branches, or the angles at F and D, G and H. - - This is usually explained by saying, that since the parts of a fluid are easily moveable in any direction, the higher parti- cles will descend, by reason of their superior gravity, and raise the lower parts till the whole comes to rest in a horizontal plane. Now, what is called the horizontal plane is, in fact, a portion of a spherical surface, whose centre is the centre of the earth: hence it will follow, that if a fluid gravitate towards any centre, it will dispose itself into a spherical figure, the cen- tre of which is the centre of force. - * - Prop. If a fluid, considered without weight, is contained in any vessel whatever, and, an orifice being made in the vessel, any pressure whatever be applied thereto, that pressure will be distributed equally in all directions. . Through any point N, fig. 1, taken at pleasure below the sur- face of the fluid LIK M, imagine the horizontal plane PNO Q. P R. E. P R. I DICTIONARY OF MECHANICAL SCIENCE. 839 to pass. It is obvious, the weight of the fluid contained in the vessel below P N O Q, contributes nothing to the support of the columns LP, IO, MQ, so that the equilibrium would obtain in like manner, if the fluid contained in that part of the vessel below P N O Q had lost its weight entirely: We may, there- fore regard this fluid as being solely a mean of communication between the columns LP, IO, M Q ; in such manner that it will transmit the pressure resulting from the columns, LP, MQ, to the column IO, and reciprocally. If now, instead of the columns LP, IO, M. Q, of the fluid, pistons were applied to the surfaces P, N, O, and Q, and were separately urged by pressures respectively equal to the pressures of the columns LP, IO, M. Q, the equilibrium would manifestly obtain in like manner. Or if a pressure, equal that of the column M Q, be applied at Q, while the columns LP, IO, remain, the equili- brium will still obtain; and this, whatever are the directions of the several branches, and their sinuosities at D, F, &c. whence the proposition is evident. Cor. 1. Not only is the pressure transmitted equally in all directions, but it acts perpendicularly upon every point of the surface of the vessel which contains the fluid. For, if the pressure which acts upon the surface were not exerted perpendicularly, it is easy to see that it could not be entirely annihilated by the reaction of that surface; the surplus force would, therefore, occasion fresh action upon the particles of the fluid, which must be transmitted in all directions, and occasion a motion in the fluid ; that is, the fluid could not be at rest in the vessel, which is contrary to experience. Cor. 2. Hence also, if the parts of a fluid, contained in any vessel A B C D, open towards the part A B, are solicited by any forces whatever, and remain, notwithstanding, in equi- librio, these forces must be perpendicular to the surface A. B. For the equilibrium would obtain, if a cover or a piston of the same figure as the surface A B, were applied to it; and it is manifest, that in this case, the forces which act at the surface, or their resultant, must be perpendicular to that surface. Cor. 3. If, therefore, the forces which act upon the particles of the fluid are those of gravity, the direction of gravity is per- pendicular to the surface of a tranquil fluid ; consequently, the surface of a heavy fluid, to be in equilibrio, must be horizontal, whatever may be the figure of the vessel in which it is contained. Cor. 4. If a vessel, as A B C D, closed throughout, except a small orifice O, is full of a fluid without weight, then if any pressure be ap- plied at O, the resulting pressure on the plane surface or bottom C D, will neither depend upon the quan- tity of fluid in the vessel, nor on its shape; but since the pressure ap- plied at O, is transmitted equally in all directions, the actual pressure upon CD will be to the pressure at O, as the area of C D is to that of the orifice. * Cor. 5. In the same manner will the pressure applied at O be exerted in raising the top AB of the vessel; so that if the top be a plane, of which O forms a part, the vertical pressure tending to force A B upwards, will be to the force applied at O, as the surface A B to the area O. See HYDRostAtic Bellows. PROP. The pressure of a fluid on the horizontal base of a C S-ºp vessel in which it is contained, is as the base and perpendicular altitude, whatever be the figure of the vessel that contains it; the upper surface of the fluid being supposed horizontal. A. lº, A. E. I5 Let any horizontal plane, GH, be supposed drawn, and con- ceive the fluid contained in the part G. C D H of the vessel to be void of weight; then, as it is evident, from cor. 3 of the foregoing proposition, that any vertical filament whatever, EI of the heavy fluid A B HG, exerts at the point I a pressure, ; which is distributed equally through the fluid G C D H ; and that this pressure acts equally upwards to oppose the action of each of the other filaments which stand vertically above GH; therefore, the filament E I alone kceps in equilibrio all the other filaments of the mass A G H B ; consequently, the mass G C D H being still supposed without weight, there will not result any other pressure on the bottom C D than that of a single filament E I; which, being transmitted equally to all the points of CD, will make the pressure upon CD to that upon the base I of the filament E I, as the area of C D to the area I. If, therefore, we imagine a heavy fluid contained in A CD B, to be divided into horizontal laminae, the upper lamina will communicate to the bottom C D, no other action than would be communicated by the single filament a b ; and the same thing obtaining with respect to II each lamina, the bottom therefore is a pressed in the same degree as it would be by the combined operation of the Iz filaments a b, b c, c d, &c. Whence, as this pressure is transmitted equally to all points of CD, it will be equal to the product of C D into the sum of the º pressures which the filaments a b, b c, c d, are capable of exercising on the same point, or it will be proportional to C K x (a b + b c + c d --, &c.).-Gregory's Mechanics, article 384, &c. - : Centre of PR essure. See Centre. PREWARICATION, in the Civil Law, is where the informer colludes with the defendants, and so makes only a sham pro- secution. w PREVENTER, in naval language, an additional rope em- ployed at times to support any other, when the latter suffers an unusual strain, particularly in a strong gale of wind. Pre- venter-brace, a temporary brace, fixed occasionally to succour the main or fore yard, or to supply the place of the usual braces, in the event of their being shot away in action. Pre- venter-stay, is a smaller stay, fixed above the standing one, and serves to relieve the latter, or to supply its place. Pre- venter-shrouds, are applied to serve the same purposes. . PRICE, DR. RICHARD, a celebrated English mathematician, fellow of the Royal Society, and of the Academy of Sciences, New England, was born at Tynton, in Glamorganshire, in 1723, and died in London, in 1791, in his sixty-eighth year. PRICK, in seafaring language, is a term applied to a roll of small rope, &c. as a prick of spun yarn, a prick of tobacco. PRICKING, in the sea language, is to make a point on the plan or chart, near about where the ship then is, or is to be at such a time, in order to find the coure they are to steer. . PRICKING a Chart, the act of tracing a ship's course upon a marine chart, by the help of a scale and compasses, so as to discover her present situation. Pricking a Sail, is the running a middle seam between the two seams which unite every cloth of a sail to the next adjoining, and is rarely per- formed till the sails have been worn some time. - PRIMAEWIAE, among Physicians, denote the whole alimen- tary duct; including the oesophagus, stomach, and intestines, with their appendages. - - PRIMARY ROCKS, are so called by the Wernerians, because therein no organic remains have been found, hence it is supposed they were formed prior to the creation of animals or vegetables. The are extremely hard, and their substances are pure crystallized matter, in large vertical masses, more or less inclined to the horizon, and without fragments, or other rocks. They form the lowest part of the earth's surface with which we are acquainted; and not only constitute the foun- dation on which the other rocks rest, but in many situations pierce through the incumbent rocks and strata, and form the highest mountains in alpine districts. - - PRIMARY Planets, are such as revolve about the sun as a centre; such are Mercury, Venus, Terra the Earth, Mars, Vesta, Juno, Pallas, Ceres, Jupiter, Saturn, and Uranus or the Georgium Sidus; being thus called in contradistinction to the R" 4A. T. & G\----------5 g * w - - - -------Cl- - - - - -: - - - - tº g * tº g -4-----d; gº t t t * * * * * * * * * * * 62 C 3. secondary planets or satellites, which revolve about their re- spective primaries. See PLANET. - PRIMALTES, in Natural History, the first order of mamma- lia in the Linnaean system. The animals in this order are fur- P. R. I P R I DICTIONARY OF MECHANICAL SCIENCE. nished with fore-teeth or cutting-teeth: the four above are parallel; two breasts on the chests. There are four genera, viz. Hemo, Lemur, Simia, Vespertilio. PRIMING, or PRiMe of a GUN, is the gunpowder put into the pan or touch-hole of a piece to give it fire thereby ; and this is the last thing done in charging. For pieces of ordnance they have a pointed iron rod, to pierce the cartridge through the touch-hole, called primer or priming-iron. PRIME NUMBeRs, are those which have no divisors, or which cannot be divided into any number of equal integral parts, less than the number of units of which they are composed; such as 2, 3, 5, 7, 11, 13, 17, &c. These numbers have formed a sub- ject of investigation and inquiry from the earliest date down to the present day; and a rule for finding them is still amongst prime number beyond a certain limit, by a direct process, is considered one of the most difficult problems in the theory of numbers; which, like the quadrature of the circle, the trisec- tion of an angle, and the duplication of the cube, have engaged the attention of many able mathematicians, but without arriv- ing at any satisfactory result. - PRiMe Vertical, is that vertical circle, or azimuth, which is perpendicular to the meridian, and passes through the east and west points of the horizon. PRIME Werticals, in Dialling, or PRiMe Vertical Dials, are those that are projected on the plane of the prime vertical cir- cle, or on a plane parallel to it. These are otherwise called direct, erect, north, or south dials. - . PRIME of the Moon, is the new moon at her first appearance, for about three days after her change. It means also the Golden Number, which see. PRIMULA OfficINALis. (The Cowslip.) The flowers ap- pear in April ; they have a pleasant sweet smell, and a sub- acrid, bitterish, subastringent taste. An infusion of them, used as tea, is recommended as a mild corroborant in nervous com- plaints. A strong infusion of them, with a proper quantity of sugar, forms an agreeble syrup, which for a long time main- tained a place in the shops. By boiling, even for a little time, their fine flavour is destroyed. A wine is also made of the flowers, which is given as an opiate. PRIMUM Mobile, in the Ptolemaic Astronomy, the ninth or highest sphere of the heavens, whose centre is that of the world, and in comparison of which the earth is but a point. This the ancients supposed to contain all other spheres within it, and to give motion to them, turning itself, and all of them, quite round in twenty-four hours. - PRINCE, a person invested with the supreme command of a State. ºr's Metal, a mixture of copper and zinc, in imitation of gold. - PRINCIPAL, in Arithmetic or in Commerce, is the sum lent upon interest, either simple or compound. See INTERest. PRINCIPAL and Accessary, in Criminal Law, principal is the person who himself commits the offence. An accessary is a person who participates by advice, command, or concealment. There are two kinds of accessaries; before the fact, and 'after it. The first is he who commands or procures another to com- mit felony, and is not present himself; for if he be present, he is a principal. The second is he who receives, assists, or com- forts any man that has done murder or felony, whereof he has knowledge. A man may be accessary to an accessary, by aiding, receiving, &c. an accessary in felony. An accessary in felony before the fact, shall have judgment of life and member, as well as the principal who did the felony: but not till the principal be first attainted, and convicted or outlawed thereon. Where the principal is pardoned without attainder, the acces- sary cannot be arraigned; it being a maxim in law, Ubi non est principalis, non potest esse accessorius. But if the principal be pardoned, or have his clergy after attainder, the accessary shall be arraigned. 4 and 5 W. and M. cap 4; and by stat. 1 Anne, cap. 9, it is enacted, that where the principal is con- victed of felony, or stands mute or challenges above twenty of the jury, it shall be lawful to proceed against the accessary in the same manner as if the principal had been attainted ; and notwithstanding such principal shall be admitted to his clergy, pardoned or delivered before attainder. In some cases also, if the principal cannot be taken, then the accessary may be prosecuted for a misdemeanor, and punished by fine, imprison- ment, &c. stat. ib. see stat. 5 Anne, cap. 31. In the lowest and highest offences there are no accessaries, but all principals: as in riots, routs, forcible entries, and other trespasses, which are the lowest offences. So also in the highest offence, which is according to our law high treason, there are no accessaries.— Coke. - . . . . . . . . . . , PRINGLE, SIR John, a very distinguished physician, and philosopher, was born in Roxburghshire in 1707, and took his degree of M.D. at Leyden in 1730; and there published his. “Dissertatio de Marcore Senili,” in 4to. In 1766 he was elected President of the Royal Society, an honour which he - resigned in 1778, and died in 1782. - * * the desiderata of mathematicians. The method of finding a | PRINT, the impression taken from a copper-plate. . . PRINTING, in its general signification, is the art of taking impressions from characters or figures, moveable or immove- able, on paper, vellum, linen, silk, &c,. . Of printing, there are four kinds; one, from plates of copper or steel for pictures, (see Copperplate Printing); another, from blocks, in which birds, flowers, &c. are cut for linen, (see Calico Printing); a third, from solid metal pages, cast for the printing of books, (see Stereotype); and finally, as of more importance than either, from moveable letters, to which the world is so much indebted for the treasures of literature with which it is enriched. It is somewhat remarkable, that while the art of Letter PREss PRINT ING has formed a new era in the history and character of man, the origin of its invention is involved in mysterious obscurity. The primitive honour of having given birth to this . sublime vehicle of knowledge, has been claimed by Mentz, Strasburg, Harlem, Dordrecht, Venice, Rome, Florence, Basle, and Augsburg. the only places that can advance formidable reasons in favour Harlem, Mentz, and Strasburg are, however, of their respective claims; but the decision of this much dis- puted question lies not within the province of this work. It is admitted by all partics, that this important invention took place about the year 1440, and was brought to England by William Caxton, who set up his first press in Westminster Abbey, and began to print books soon after the year 1471. Since that period, considerable improvements have been made in various branches of the art, but more particularly so in the construction of presses, the increase and application of power, the diminution of manual labour, and the facilities given to expedition. In the early days of printing, the presses were invariably made of wood, and in general construction bore a strong resemblance to those now in use. The representation of one bearing the date of 1560, is now before us, and its appearance is not essentially different from the improved wood press, in the annexed figure, which we proceed to describe. See the Plate Printing Presses. The body of the press, fig. 1, consists of two strong posts, b, called the cheeks, placed perpendicular, and joined together by four horizontal cross pieces ; the upper of these, a, is called the cap, and has no office but to retain the two cheeks at their required distances, and support the heads; the next cross piece, c, is called the head; it is fitted by tenons at the ends into mortises between the cheeks, and these mortises are filled up with pieces of pasteboard or soft wood, in such a manner as to admit of a small motion, or yielding. The head is sustained by two long screw-bolts, which suspend it from the cap: in the head is fixed a brass nut, containing a female screw or worm, which is fastened in the wood by two short bolts to keep it up : the worm is adapted to receive the screw by which the pres– sure is produced. The third cross piece, e, called the shelves, or till, is to guide and keep steady a part, i, called the hose, in which the spindle of the screw (to be spoken of hereafter) is enclosed. The fourth cross plank, f, called the winter, is fitted between the cheeks to bear the carriage; it sustains the effort of the press beneath, as the head does above, each giving way a little, the one upwards, the other downwards, to make the pull the easier. The spindle, g, is an upright piece of iron, pointed at the lower end with steel, having a male screw formed on its upper end, which enters about four inches into the female screw or worm fixed in the head: through the eye of this spindle is fixed the bar or handle, h, by which the pressman works the , - - * / / / // ("Z 2 %. ſº ºf Z/0, x - 27 ºl 2- - º º P R I P R. 1 841. DICTIONARY OF MEGHANICAL SCIENCE. press. The platen, k, or surface which acts upon the paper to produce the impression, is suspended from the point of the spindle by means of a square block or frame of wood, i, called the hose, which is guided by passing through the shelves, e e : the lower part of the spindle passes through the hose, and its point rests upon the platen k, being received into the phag fixed in a brass pan supplied with oil, which pan is fixed to an iron plate let into the top of the platen k. The pressman then, by pulling the bar h, fixed in the eye of the spindle g by an iron key, turns the spindle, and by means of its screw presses down the platen upon the form of types, which is covered with the paper, tympan, and its blankets, all these parts being brought under the platen by the carriage; when the impression is to be given. That the platen may be suspended from the spindle, and rise up again with it, the hose, i, is attached to the spindle by the garter; this is a fillet of iron screwed to the hose, and entering into a nick or groove formed round the upper part of the spindle; it prevents the hose falling down on the spindle. At each corner of the lower part of the hose there is an iron hook fastened, and from these to similar hooks, fastened at each corner of the platen it, cords or packthread are looped to sus- pend the platen, and they are exactly adjusted, to hang the platen truly level. The carriage l, which is the other principal part of the press, is adapted to run into the space between the cheeks under the platen. It is supported upon the ribs n, which are part of a horizontal wooden frame, having its fore-part supported by a wooden prop m, called the fore-stay, while the other end rests on the winter. On the rails of this frame two long iron bars or ribs are nailed, and under the plank of the carriage are nailed short pieces of iron or steel, called cramp irons, which slide upon the ribs, when the carriage is run in or out, by the follow- ing means. Beneath the carriage is placed a small spindle called the spit, with a double wheel formed in the middle of it, round which leather girths are passed and fastened, the oppo- site ends being mailed to each end of the plank l of the car- riage. On the extreme end of the spit is fixed the handle or rounce by which the pressman turns the spit, and this, by by means of the wheel and straps, runs the carriage in or out at pleasure. The carriage itself consists of a strong wooden plank l, upon which a square frame of wood is fixed, to form e coffin or cell, in which a marble or polished stone is en- closed, for the form of the types to be laid upon. To this coffin are fastened leather stay-girths, one to each end, which being at the opposite ends fastened to the horizontal frame, prevent the carriage running too far out, when drawn from under the platen. On the fore-part of the plank is a gallows r, which serves to sustain the tympans, when turned up from off the form, on their hinges. The tympans, s, are square frames covered with parchment. The frames are made of three slips of very thin wood, and at the top a slip of iron, still thinner, called a head-band. The two tympans are fitted together by the frame of one being small enough to lie within the other : the outward tympan is fastened with iron hinges to the coffin. Between the two parchments of the tympans one or two thick- nesses of blankets are placed, which serve to make the impres- sion of the platen upon the surface of the letters more equal, as also to prevent the letters from being broken by the force of the press. The use of the inner tympan is, to confine these blankets. The friskett, is a square frame of iron, made verythin, also covered with paper or parchment, and fastened to the head- band of the outer tympan by hinges: it folds down upon the tympan, to enclose the sheet of paper between them, the parch- ment or paper with which the frisket is covered being cut out in the necessary places, that the sheet, when placed between the tympan and frisket, and both together folded down on the form, may receive the ink from the types in the pages; but the frisket sheet keeps the margins clean. The tympan and frisket, when folded down, lie flat upon the form, and the carriage with them is run into the press; but when the sheet is to be taken out, the tympan is lifted up upon its hinges, and rests as repre- sented, in an inclined position against the gallows r, before mentioned, at the back part of the carriage; then the frisket t is lifted up on its hinges, and sustained by a slip of wood w, hanging from the ceiling, whilst it continues open, to take out the printed sheets and put in others, . . machine. To regulate the margin, and make the lines and pages answer each other when printed on the opposite side of the sheet, two iron points are fixed to the middle of the wooden sides of the frame of the tympan, which make two holes in the sheet. These holes are placed on the same pins, when the sheet is returned for making an impression on the other side, which is called the reiteration, and the pins are adjustable, that they may make the impressions of the opposite sides exactly correspond. The ink, when the improved inking cylinder is not employed, is applied upon the form by balls, which are a kind of wooden cups with handles, the cavities of which are filled with wool, or hair, covered with prepared sheep’s skin nailed to the wood. Qne of these the pressman takes in each hand, and applying them on the ink-block u, to charge them with ink, he works them one against the other, to mix and distribute the ink equally; and, at last, inks over the form, by beating or dab- bing them several times over the whole face of it; this leaves the form in a condition to be passed under the press, with the moistened paper laid on it. - The taste for elegant typography, and the increased demand for books of every description, which followed the rapid exten- sion of arts, sciences, and literature, throughout Europe, soon rendered an improvement on the printing press a desideratum, It was found that the common press was deficient in the neces- sary power to produce a sharp and beautiful impression from the types. Besides this deficiency of power, which rendered the pressmen's operations ºvery laborious, another was, that only the half of the sheet could be printed at a time. Among the first attempts to remedy these defects, was an improvement made in France. It consisted of a wooden press of the com- mon construction, having a platen formed of iron, instead o. wood, and made sufficiently large to print the whole side of a sheet of paper at once. The under surface of this plate was covered with brass. The screw, or spindle, instead of being turned by the bar, or lever, in the usual manner, was connected by rods, with a strong lever placed at the side of the press, and was worked by the application of both hands to the lever to bring it down nearly in the same way as when working the lever of a common pump. Though additional power was then procured, the exertion required from the pressmen was too great, to bring this press into general use. A patent was taken out in the year 1796, by Mr. Prosser, of London, for an im- provement in the printing press, which consisted chiefly in a mode of increasing the power, by the addition of a spring be- tween the cap and head, to resist the pressure upwards, and a similar one under the lower board or winter, to resist the pres- sure downwards. Another improvement adapted to the common press, was made by Mr. Roworth, a printer in London, and was found to be successful in practice. For the screw, he substituted a plain vertical spindle, furnished with a bar, hose, &c. as in the com- mon press; but the upper part, where the thread of the screw is usually cut, was a plain cylinder, fitted into a socket in the head of the press. Upon the upper end of the spindle, just beneath the head, a short cross arm is fixed, which acts against a circular inclined plane, fixed under the head of the press. When the bar or lever is turned, this short arm, acting on the inclined plane, causes the spindle to descend in the same manner as the screw ; but with this advantage, that the inclined plane is formed so as to give a rapid descent to the spindle when the action first begins; and when the platen comes in contact with the tympan and types, and the pressure is begun, the plane has a very slight inclination, and a power which increases as the resistance increases. Mr. Brown of London, in 1807, took out a patent for im- provements in the construction of a press, &c. part of which may be applied to presses now in common use. His press was made of iron, and the pressure produced by a screw, which was put in action by a bevel wheel and pinion. The handle which put these parts in motion, was fixed on a spindle or shaft, attached to the side of the press. The most successful improvement on the printing press was made about this time by the late Earl Stanhope; whose genius for mechanics led him to turn his attention to this important The Stanhope press is formed of iron, and prints the 10 E - 842. P R 1 P R. I. DICTIONARY OF MECHANICAL SCIENCE. whole side of a sheet of paper at once. The most important part of the invention consists in having obtained, by a com- bination of levers, the requisite degree of pressure without the excessive labour of the common press, where the lever or bar is fixed on the axis of the screw. A short lever is applied upon the top of the screw, and is connected by a link with the extre- mity of another lever, which is fixed upon the top of a spindle or axis placed parallel to the screw. To the lower end of this spindle, the handle or lever for working the press is attached; and the relative position of the levers is such, that when the pressman first pulls the handle towards him, the platen is moved or brought down with a considerable yelocity; but when it ar- rives at the position where the pressure is required, the levers have changed their position in such a manner as to operate upon the platen with a very slow motion, and a power immensely great. This principle has been employed with certain modifi- cations in almost every kind of printing-press that has been brought forward since the period of Lord Stanhope's invention. A view of this press (see the Plate, fig. 2,) will aid the reader in forming an idea of its construction. - - For a professed improvement upon the Stanhope press, a patent was taken out by M. de Heine in 1810. The principle of this invention is the application of two sectors, or a sector. and a cylinder, or a sector and a roller, to move against the other by a single or compound lever. The only material im- provement is the substitution of a spiral or curved inclined plane, instead of the screw. - . Some improvements were also made by Mr. Keir, on the con- struction of the Stanhope press, which have been considered as contributing much to its accurate working and durability. A cylindrical hole is bored in the centre of the press, into which a cylinder is accurately fitted, with the platen fixed on its lower end. To prevent the cylinder from turning round, it is made with a flat side, and a bar of iron, screwed across the two cheeks, bears against this side. Another improvement consists in the spindle, to which the handle is fixed, having a screw cut upon its lower end, which is fitted into a nut, so that when it is turned round, the spindle rises and falls a space equal to that passed over by the descent of the main screw in the same time. By this means, the connecting lever always draws in a horizontal direction. In the other presses, one end remains at the level, while the other descends, which occasions the joints to wear irregularly. Mr. Brooke, about the same time, applied the compound Ievers of the Stanhope press to the common press with great success. As the wooden frame of the old press is not suffi- cient to afford the same resistance as those constructed of iron, the power of these presses is of course much inferior. This improvement, however, has been pretty generally adopted. Medhurst's printing press is said to excel in the simplicity of its construction. Besides the merit it possesses in this particu- Jar, and which renders it cheaper than the Stanhope press, it has, perhaps, a greater advantage in point of power. The pressure is produced by a peculiarly beautiful arrangement of levers, dif- fering considerably from any thing hitherto employed in machi- néry. This circumstance has led the inventor to denominate his mechanism a new power in mechanics. - This press is similar to the common one in all its parts; but the platen is made the full size of the sheet, and, instead of a screw, a plain. spindle is employed. On the lower part of the spindle: a circular collar or plate is fixed, into which the bar, or lever, which forms the handle of the press, is fastened. This plate affords steps or cups for two short iron rods or pins which extend up to the head, and are there supported by the points of two screws in the head, entering sockets cut out in the pins, which are made of steel. When the platen is up, these pins stand in an inclined position; but when the spindle is turned by the lever or handle, the circular plate in which the lower end of the pins rest turns round likewise, and, the upper end remaining stationary, they come into a vertical position. In this motion, the spindle and attached... platen are forced to de- scend in the same manner as if a screw were employed. In 1813 Mr. Ruthven took out a patent for a press, in which . necessary power is produced by a combination of levers aſ On C. All the alterations or improvements hitherto mentioned, retain the original principles of placing the types on a move. able carriage, where, after being inked, they are passed under the power for producing the impression, and then returned; the reverse of this is the construction of Ruthven's ; and as it is from this his decided point of excellence chiefly arises, we shall be a little particular in explaining it. When the types on the moveable carriage comes under the pressure, a horizontal and perpendicular motion is in action, which effectually prevents that necessary steadiness requisite to produce a clear impres- sien. In Ruthven's presses, the types are fixed on a stationary tablet; the upper surface is brought over by the side till it con- nects itself at each end with the parts under the tablet, which consists of a combination of levers and cranks, that produce an inconceivable power, and are so placed that while the power is applied at each end, the resisting point is up against the under surface of the tablet ; by this arrangement, the horizonal motion with the types is completely avoided; and as the upper sur- face cannot come in contact with the types till in a situation exactly over them, that point is gained which has been so long desired, of the upper surface descending steadily on the types. Another important object is also here attained, the power being applied at each end of the upper surface, an equality of pressure is thereby diffused, not to be attained by any other press, where the power is applied in the centre of the upper surface. The result arising from these combined advantages is not only a clearness of impression that enables a general observer to dis- tinguish the work printed by them, but, a saving in the durabi- lity of the types, from the manner of producing the impression. The improvement in Mr. Russel's printing press is derived chiefly from the two-fold application of the principle which was first introduced by Lord Stanhope, and which nearly all other press-makers have found it advisable to adopt, though in varied degrees. - - - ... • The Albion press by Mr. Cope is a contrivance of considerable merit. Its power is very great, its aggregate weight is much less than many others, and the ease with which it may be worked adds much to its importance and value ; but our limits prevent us from detailing its particular excellencies. Many other presses besides those we have mentioned have been presented to the public, of which we cannot enter into even an enume- ration. There is, however, one, the Columbian press, which from its amazing power, merits a particular, though brigf description. - - For this press we are indebted to the ingenuity and talent of Mr. George Clymer, of Philadelphia, in North America, who, after manufactured a supply of them for our transatlantic brethren, arrived in this country, in 1817, to introduce his press to the printers of Europe, which had given such universal satis- faction to those connected with the art in that portion of the globe. The highly favourable and very flattering testimonials which Mr. Clymer produced on his arrival in London, from the gentlemen connected with the press in different parts of the United States, where they had been in active operation, clearly evinced to the printers of Great Britain and Europe, that his invention was well deserving their countenance and encourage- ment; and, notwithstanding they had presses not only of the Stanhopean manufacture, but also of several others, yet the pro- perties of Mr. Clymer's Columbian press, supported by the above testimonials, was the immediate cause of their introduc- tion into several of the first houses in the metropolis, and many of the others soon followed; they were also introduced into several of the first printing-offices on the continent ; and we sincerely hope that Mr. Clymer has been handsomely remu- nerated from them for his ingenuity and ability. Of this ex- traordinary press, fig. 3, in the Plate, gives a faithful repre- sentation; the parts of which we shall briefly describe, to enable pressmen to fix them up or take them down, when they require either cleaning or removing. - This press is composed of the following parts: the feet, staple, ribs, fore-stay, rounce, main lever, elbow-piece, coun- terpoise lever, links, table, platen, piston, cheek or guide pieces, back bar, back-return lever, shoulder piece, bar, con- necting rod, eagle, &c. . . * - Having brought the staple on or near to the spot on which you intend to fix the press, then put the feet (as marked) into their respective places, and raise the staple upon them. The P .R I P R 1 DICTIONARY OF MECHANIAAL SCIENCE. 843. ribs should now be screwed to the staple, and also the leg, or fore-stay, by which the near end of them is supported, but the stay is not fastened to the floor; at the top of this stay is a projecting piece of iron, with a bolster upon it, which prevents the carriage from running back. - { - The rounce is attached to the ribs by means of caps and bolts, which are fastened to the projections from the ribs. The main lever must next be raised into its station : it is connected to the staple by a strong steel bolt, which fits accord- ing to a small mark, and is pinned on the other side, to prevent its working out. x * The elbow piece is made in the form of two sides of a tri- angle: it has one square, and three round holes through it; that at the angle is the one which connects it to the projecting part of the long side of the staple, in which is a mortise to receive it; this done, two holes will remain below, and the square one above; the centre round hole receives the bolt, on each end of which is the lower part of the links; the lower hole is for the bolt which attaches the knob piece to the long end of the elbow piece: on the upper end of the last mentioned is the square hole for connecting the back-return lever. . The counterpoise lever (whereon stands the eagle, which causes the return of the platen and bar) works on two pivots on the top of the long side of the staple, and rests upon a small piece of wood in the mouth of the dolphin, on the upper part of the main lever. The counterpoise and main levers are con- nected by means of a short brass rod, with a hook at one end, and a screw at the other; the former fits into the mouth of the dolphin at the end of the counterpoise lever, and the latter passes through a hole at the end of the main lever, which is drawn up by a nut on the under side, and by which nut the main lever, and consequently the platen, are raised or lowered at pleasure, by screwing or unscrewing this nut. . The links fit on each side of the main lever and the elbow piece, to which they are attached by means of two steel bolts, which are pinned on the opposite side, to prevent their working out; by these links the main lever is drawn down when the impression is taken. - . The table is an iron surface turned off in a lathe to the greatest exactness, with long cramps underneath, which run in the ribs, and which act as bearers to the table when the impres– sion is taken; the girths from the barrel of the rounce are fastened to projections attached to the table in the usual man- ner; corner irons are screwed on as well as the tympan joints, as before described. • * - . The platen is also turned off in a lathe, so as to meet the even surface of the table: in the centre is a high Square, on which the piston is fixed, with four holes to receive the ends of the side-headed screws which secure the piston to the platen; ridges project from this square to the ends, corners, and sides of the latter, by which it is prevented from springing when the pull is made ; the platen should now be placed on the table with two pieces of wood, about letter height, underneath ; the four side-headed screws are next put into their respective holes in the platen (as marked,) and the small wedges placed behind to keep them in their stations: a square piece of iron, or pieces of sheet iron or tin, are laid in the centre of the platen to increase or reduce the power. The piston is now lifted on the small piece of iron in the centre of the platen, and the screws passed through the four holes in the former, and the nuts screwed on, which bind the piston and platen together; care should be taken that the marked sides of the platen and pis- ton are both kept in the front. The table, with the piston and platen, is now run to the centre of the staple, which will bring the upper part of the piston directly under the trunnion of the main lever, which is connected to the piston by means of the caps and bolts attached to the latter. The platen must be regulated by the screws which secure the piston, when a form is laid on. . The cheek, or guide pieces, which the angles of the piston slide through, and which keep the piston and platen steady, fit on two projections from the insides of the staple, and are fastened by four bolts with nuts and screws. The left-hand. one is tightened by means of a small key, or wedge, which passes between the projection from the staple and the cheek pieces; on the right hand one is a piece of iron with a screw through it, which the elbow of the bar strikes against when the latter is brought down ; this screw is for the purpose of par- tially regulating the power. - . The back bar slides into two bevels on the back of the staple, behind the main lever, which is for the purpose of preventing the staple from springing, when the power is applied by means of the bar. •e - The back-return lever fits into the square hole in the upper angle of the elbow piece; it has a small sliding weight, which acts a counterpoise to the eagle on the top lever. The bar, or shoulder piece, fits into two projections from the off-side of the staple, to which one end is attached by a steel bolt, and in the other is a square hole made to receive the end of the bar, which is pinned on the inside : the middle of the shoulder piece is cast hollow, to admit one end of the connect- ing rod, which is attached by a small bolt. - The connecting rod is made of wrought iron: one end has an eye, which fits between the hollow in the middle of the shoulder piece, through both of which pass a small pin; the other end is tapped, to screw on the swivel attached to the knob piece, and by which, from the bar, the whole machine is put into motion. It should be recollected, that one side of the eye is filed away to admit the rod to vary a small degree from a right angle, otherwise it would not meet the swivel attached to the knob piece. To increase the power, take out the small bolt in the middle of the shoulder piece, and turn the rod to the right; that is, take up the screw : to diminish it, turn the rod to the left, viz. lengthen the rod by unscrewing: the filed part of the eye must always be kept downwards. * Composition Inking Balls.-Having noticed the principal im- provements that have been made in printing presses, those which have taken place in the means of supplying the type with ink must not be omitted. Until of late, the common pelt balls, consisting of sheep skin stuffed with wool, and nailed to the ball stock, were in constant use, and in many places their services are still retained. About the year 1816 composition balls first made their appearance at Weymouth, being made by Mr. B. Foster, a compositor, of that place. At first their intro- duction was much opposed by many masters and pressmen in London, but they have gradually gained ground and got into general use. These balls are made of molassses, glue, and a portion of târ, which are boiled together to a proper consist- ency. It is then poured on a piece of cloth, and when suffi- ciently cold is nailed to the ball-stock, like the common sheep skin. Should these balls be hard, when dirty, they may be washed with a little weak lie, and rinsed with water; if soft, a little ink may be laid on them and scraped : but every pressman must use his own judgment, as variations will arise from boiling and the state of the weather. When the Times newspaper was first printed by machinery, the power being cylindrical, rollers were indispensably neces- sary. These were formed of the above composition, and being found to answer the expected purpose, in 1819 hand rollers were introduced to the notice of the pressmen. These came very rapidly into use, and are likely to continue. They are coated with the above composition, and made in the form represented in fig 4. They have been found admirably adapted for heavy forms, but not so well for light ones, and are subject to the changes of the weather. The inking frames or tables by which the rollers are supplied with ink, are constructed as represented in fig. 5. The whole is composed of iron, with the cylinder turned off to the greatest exactness, under which is a steel edge that scrapes the ink off the cylinder, to the exact quantity re- quired. This is regulated by means of counterpoise levers that pass under the table, on which are hung two weights, to be removed according to the quantity required for the work in hand. One end of each laver passes against the ductor or regulator. The ductor and cylinder are fixed so closely toge- ther that, the cavity will hold water, and consequently no ink can escape more than is actually wanted. The cylinder has an ornamental cover, which is always kept on, except when a fresh supply of ink is required. . By this means all dust and dirt is kept from the ink and the cylinder. The latter is moved by a small handle at the end. The table is turned off in a lathe perfectly true, the same as in the presses. - Printing Machines.—Among the numerous inventions of the ‘844 Tº R I P R f DICTION A Rºy OF MECHANICAL SCIENCE, present age, those of machines for printing are not the least remarkable, Prior to their introduction, the press department was one of great labour, whenever extraordinary expedition was required. This was particularly the case with newspapers, of which, with the utmost exertion, scarcely ever more than 750 copies could be produced in an hour. The consequence was, that in newspaper offices, where the circulation was extensive, it was found necessary, in order to get the paper published in time, to compose two or more copies, so that by going to press at the same time, the demands of the public might be complied with ; thus occasioning an enormous increase of expenditure both in the compositors' and press departments. In a news- paper circulating seven or eight thousand copies, this expense, annually, could not have been less than £2000; all of which has been saved by the introduction of machines, which are worked by steam or hand. The first machine used in London was made, we believe, by two Saxons, named König and Baur, in 1814. This machine, or one upon a similar principle, is now in use, worked by steam, at the Times’ office, and there are others in various other offices. The great expense of erecting machines worked by steam, led to the invention of others, which are worked by hand, but which have been liable to many objections on the score of the labour requisite in turning the wheel, and the injury to the type. It appears, that Mr. Miller, of Fleet-street, after an ex- penditure of several thousand pounds, and the most unwearied exertions, has succeeded in producing a machine capable of working 2000 sheets per hour, without any danger of accident, and with comparatively little labour to the persons employed; whilst, from the simplicity of the construction, and the regula- rity of the action, the type has not even the ordinary wear of the common printing press. The machine, which appears in fig. 6 in the engraving, will communicate to the reader some idea of the manner in which the operation is performed :-A boy is represented as laying on A, the sheet of white paper, B is the cylinder which prints the first side of the paper, C intermediate cylinders over which { the paper travels to D, the cylinder which gives the final im- ression. At E are the inking rollers, under which the form that is, the types) is in the act of passing; F is the reservoir of ink, from which the inking rollers are supplied; G is the form receiving the last inking under the printing cylinder. At H, is seen a sheet just delivered into the hands of another boy, whose business it is to keep the sheets, as they come out, in a heap. The lines at the top of the machine represents the tapes which run round the cylinders and secure the sheet. In this curious process the form of types is placed on a car- riage, which slides backwards and forwards, along rails upon | the fixed frame of the machine, so as to pass beneath the sur- face of the large printing cylinder. The blank sheet of paper being laid on the tympan, is carried down between rollers and tapes under the cylinder, which presses it upon the form of types, and prints it. It is thence conducted forwards, and delivered on other tapes to the boy who is stationed to receive it. The tapes which carry the sheet of paper along the surface of the cylinder, are narrow enough to lie in the spaces between the pages for printing ; they, therefore, do not prevent the sheet from applying itself to the types, although they pass entirely across its surface, so as to keep it in place. These tapes are arranged over small pulleys, which can be fixed at any required distance apart, so as to accord with the spaces between the pages for printing different kinds of work, such as folios, quartos, octavos, &c. The mode of procuring register is by points, which can be moved with every facility in any direction. The machine has two distinct sets of inking apparatus, one at each end, being so arranged as to furnish and distribute the ink, by means of elastic composition rollers, upon the form of types, as it moves backwards and forwards underneath them. The reservoirs of ink from which the rollers are sup- plied, are fixed on each end of the carriage, near which are also other rollers to distribute the ink uniformly over the sur- face of the inking rollers. The rollers being made to pass. twice over the types, before an impression is made from them, produce an effect in inking them, equivalent to what would be afforded by passing the common inking roller four times over them, which is all that is: usually deemed necessary to distri- bute the ink equally over the types, so as to render the impresa sion clear and uniform. The feeding roller is supplied with ink by means of a trough and regulating scraper. While the impression is being produced, the receiving roller is brought in contact with the feeding roller while in motion, and receives a sufficient quantity of ink for the next impression, while the type carriage is returning to its first position. The distributing roller, whilst revolving, has, at the same time, a lateral motion given to it, in order to distribute the ink over the whole sur- face of the composition rollers. The power of the pressing cylinder, and of the inking roller, can be regulated and adjusted with mathematical accuracy, so that a strong or a light im- pression, as the nature of the work may require, can be given with the utmost nicety. - Several of these printing machines are now in constant use in the metropolis, varying from each other in some subordinate particulars, but all founded on one common principle. Since the first introduction of machines, they have been considerably simplified, particularly in the complexity of their inking appa- ratus. For this we are indebted to the genius of . Messrs. Applegath, and Cowper, who have produced a machine far superior to that by Mr. Koenig, and which possesses nothing in common with it, but the pressing cylinders, the inking rollers, and the tapes to hold the sheet of paper on the cylinders. The pressing cylinders and inking rollers were first suggested by Mr. Nicholson; and tapes are similarly used in machines for the ruling of paper for account books. These gentlemen, there- fore, though producing their machine subsequently to Mr. Koenig, cannot, with justice, be accused of having, in the slightest degree, infringed upon his invention, Mr. Kočnig's machine possessed originally sixty wheels; Messrs. Applegath and Cowper's but sixteen ; and the machines of the former are now almost entirely superseded, even in the office of Mr Bens- proved machines of Applegath and Cowper. ley, the principal proprietor of Koenig's patent, by the im- PRISM, in Geometry, is a body, or solid, whose two ends are any plain figures which are parallel, equal, and similar ; and its sides connecting those ends are parallelograms. Hence, every section parallel to the base, is equal and similar to the: base; and the prism, may be considered as generated by the parallel motion of this plane figure. , Prisms receive particular names, according to the figure of their bases; as a triangular prism, a square prism, a pentagonal prism, a heavagonal prism, and so on. And hence the denomination prism comprises, also the cube and parallelopipedon, the former being a square prism, and the latter a rectangular one. And even a cylinder may be considered as a round prism, or one that has an infinite number of sides. Also a prism is said to be regular or irregu- lar, according as the figure of its end is a regular or an irregu- lar polygon. The axis of a prism, is the line conceived to be drawn lengthways through the middle of it, connecting the centre of one end with that of the other end. Prisms, again, are either right or oblique. A right prism is that whose sides and its axis are perpendicular to its ends, like an upright tower. And an oblique prism, is when the axis and sides are oblique to the ends; so that, when set upon one end, it in- sides. clines on one hand more than on the other. The principal pro- perties of prisms are, 1. That all prisms are to one another in the ratio compounded of their bases and heights. 2, Similar prisms are to one another in the triplicate ratio of their like 3. A prism is triple of a pyramid of equal base, and height; and the solid content of a prism is found by multiply- ing the base by the perpendicular height. 4. The upright sur- face of a right prism is equal to a rectangle of the same height; and its breadth equal to the perimeter of the base or end. And therefore such upright, surface of a right prism, is found by multiplying the perimeter of the base by the perpendicular height. Also the upright surface of an oblique prism is found. by computing those of all its parallelogram sides separately, and adding them together. And if to the upright surface be added the areas of the two ends, the sum will be the whole. surface of the prism. - • * - . . . PRISM, in Optics, is an instrument employed for shewing the properties of solar light, and consists merely of a triangular prism of glass, which separates the rays of light in their pas- . P R I . P R O .845 DictionARY of MechANICAL scIENCE. sage through it, in consequence of the different degrees of refrangibility that has place in the component part of the same ray. It is, for instance, by means of this instrument that the origin of colours is shewn to be owing to the composition which takes place in the rays of light, each heterogeneous ray consisting of innumerable rays of different colours. Thus, a ray being let into a darkened room, through a small round aperture z, and falling on a triangular glass prism ar, is by the refraction of the prism considerably dilated, and will exhibit on the opposite wall an ob- ; long image a b, called a spectrum, variously coloured, the extremities of which are bounded by semi- circles, and the sides rectilinear. The colours are commonly divided into seven, which, however, have various shades, gradually intermixed at their juncture. Their order, beginning from the side of the refracting angle of the prism, is red, orange, yellow, green, blue, purple, and violet. The obvious conclusion from this experiment is, that the several component parts of solar light have diſſerent de- grees of refrangibility, and that each subsequent ray in the order above mentioned, is more refrangible than the preceding. As a circular image would be depicted by the solar ray unre- fracted by the prism, so each ray that suffers no dilation by the prism would mark out a circular image O. Hence, it appears that the spectrum is composed of innumerable circles of diſſer- ent colours. The mixture, therefore, is proportionable to the number of circles mixed together; but all such circles lie be- tween those of two contingent circles, consequently the mixture is proportionable to the interval of those centres ; viz. to the breadth of the spectrum. Consequently, if the breadth can be diminished, retaining the length of the rectilinear sides, the mixture will be lessened proportionably; and this is done by the following process:—At a considerable distance from the hole 2, place a double convex lens A B, whose focal length is equal to half that distance, and place the prism a behind the . lens; then at a distance behind the lens, equal to the distance z from the hole, will be formed a spectrum, the length of whose rectilinear sides is the same as before, but its breadth muc less ; for the undiminished breadth was equal to a line subtending, at the distance of the spectrum from the hole, an angle equal to the apparent diameter of the sun, together with a line equal to the diameter of the hole; but the reduced breadth is equal to the diameter of the hole only: the image of the hole formed by the lens, at the distance of double its focal length, is equal to the hole; therefore its seve- ral images, in the different kinds of rays, are equal to the same; viz. the breadth of the reduced spectrum is equal to the diame- ter of the hole. It is also known from experiment, that a prism placed in an horizontal position will project the ray into an oblong form, but if another horizontal prism be applied, similar to the former, to receive the refracted light emerging from the first, and having its refracting angle turned the contrary way from that of the former, the light, after passing through both prisms, will assume a circular form, as if it had not been at all refracted. . But if the light, after emerging from the first prism be received on another prism, perpendicular to the former, it will be refracted by this into a position inclined to the former, but its breadth will remain the same. In order now to shew that the different colours suſler no manner of change from any number of refractions, let there be placed close to the prism a perforated board, and let the refracted light transmitted through the hole be received on another board parallel to the former, and likewise perforated with a small hole; and behind this hole place another prism with its refracting angle downwards, and turn the first prism slowly about its axis, and the light will then move up and down the second board; let the different colours be turned successively, and mark the place of the dif- ferent coloured rays on the wall after their refraction at the second prism; it will then be found that the red is seen the lowest, and the violet the highest, and the rest in the inter- mediate space in their order. From these experiments, aided by some others which our limits will not admit of detailing, the following conclusions have been drawn, viz. The solar rays may be resolved into different coloured rays; these coloured rays are immutable, either by reflection or refraction. That from the mixture of these coloured rays in due proportion Solar light may be produced; and consequently that the dif- ferently coloured rays exist in solar light, though, when blended together in their natural proportions, it exhibits no traces of colour. See Colou R. - PRISMOID, a figure resembling a prism. PRISON, a gaol, or place of confinement. PRISTIS, or saw-fish, a genus of fihes of the order chon- dropterigii: there are five species. - PRIVATEER, a vessel of war, armed and equipped by par- ticular merchants, and furnished with a military commission from the state, to cruise against and annoy the chelny, by taking, sinking, or burning their shipping. PRIVILEGE, in Law, some peculiar benefit granted to cer- tain persons or places, contrary to the usual course of the Jaw. PRIVY, in Law, denotes one who is partaker, or has an interest in an affair. - . PRIVY Council, is the principal council belonging to the king, and is generally called by way of eminence the council. Privy counsellors are made by the king's nomination, without either patent or grant; and on taking the necessary oaths, they become immediately privy counsellors, during the life of the king that chooses them, but subject to removal at his discretion: no convenience now arises from the extension of the privy Council, as those only attend who are especially summoned for that particular occasion. PRIVY SEAL, is a seal that the king uses to such grants, or other things as pass the great seal. - PRIZE, a vessel taken from the enemy. Vessels are looked on as prizes, if they fight under any other standard than that of the state from which they have their commission, if they have no charter-party, invoice, or bill of lading, aboard; if loaded with effects belonging to the king's enemies, or even contra- band goods. Those of the king's subjects recovered from the enemy, after remaining four-and-twenty-hours in their hands, are deemed lawful prize. Vessels that refuse to strike may be constrained ; and if they make resistance and fight, become lawful prize if taken. By stat. 13 Geo. II. ch. 4, judges and officers failing of their duty in respect to the condemnation of prizes, forfeit £500 with full costs of suit, one moiety to the king, and the other to the informer.—The regulations with regard to prizes in the royal navy are as follow : 1. When any ship or vessel is taken from the enemy, the hatches are to be immediately spiked up, and her 'lading and furniture secured from embezzlement, till sentence is passed upon her in some court of admiralty empowered to take cognizance of causes of that nature. 2. The captain is to cause the officers of the prize to be examined : three or more of the company, who can give best evidence, to be brought to the said court of admiralty, together with the charter-parties, bills of lading, and other ships' papers found on board. Articles 3 and 4 relate to the finding any of the king's subjects in the prizes. 5. When a privateer is taken, great care is to be had to secure all the ships’ papers, especially the commission: but if there be no legal commission found on board, then all the prisoners are to be carried before some magistrate, in order to their being exa mined and committed as pirates. . PRize Money, the profits arising from the sale of such prize. In ships of war, the prize money is to be divided among the officers, seamen, &c. as his majesty shall appoint by procla- mation; but among privateers, the division is according to the agreement between the owners. - e PRIZING, the application of a lever to move any weighty body, as an anchor, &c. - e IPROBABILITY of AN Ev ENt, in the doctrine of Chances, is the ratio of the number of chances by which the event may happen, to the number by which it may both happen and fail. So that, if there be constituted a fraction, of which the nume- rator is the number of chances for the events happening, and 10 F .846 P R O P R () . DICTIONARY OF MECHANICAL SCIENCE. the denominator the number for both happening and failing, that fraction will properly express the value of the probability of the event’s happening. - PRobABILITY of Life. See Expect Ation. PROBABILITIES, the same as CHANCE8. - PROBATE of Wills, is the exhibiting and proving wills or testaments before the ecclesiastical judges. - PROBE, a surgeon’s instrument for examining the circum- stances of wounds, &c. * PROBLEM, in Logic, a proposition that neither appears absolutely true nor false, and consequently may be asserted either in the affirmative or negative. PRobleM, in Geometry, is a proposition wherein some ope- ration or construction is required; as, to divide a line or angle erect, or let fall perpendiculars. - . PRobleM, in Algebra, is a question or proposition which requires some unknown truth to be investigated, and the truth of the discovery demonstrated. - PROBOSCIS, in Natural History, is the trunk or snout of an elephant, and some other beasts and insects. PROCEDENDO, is a writ which lies where a cause is re- moved out of an inferfor to a superior court. PROCELLARIA, the petrel, in Natural History, a genus of birds of the order anseres. There are twenty-three species, of which the following are the principal:—The giant petrel, more than three feet long, and about seven wide. These birds are often seen sailing just above the water without moving their wings for a long time together, and being particularly alert on the approach of storms, often fill the mariners with apprehen- sion and alarm. They abound most in southern latitudes, and though their principal food is fish, devour also the putrid car- cases of seals and whales.—The pintado petrel, abounds about the coasts of the Cape of Good Hope. These birds are about the size of the kittiwake, and are often observed in such num- bers that many hundreds have been taken in one night.--The fulmar petrel weighs nearly a pound and a half, and is found in the northern coasts of this island, and thence even beyond Iceland and Greenland, where the natives use it for food, though its flesh is highly offensive to those not used to it. The fat is burnt in their lamps. These birds subsist chiefly on fish, but often banquet on the carcases of whales, particularly, the fat parts, which they afterwards eject from their stomachs into the mouths of their young. They often spurt it in the faces of their enemies, and exhibit indeed no other mode of resistance. They are stated to be so amazingly fat, that, on being passed through the hands with great compression, the fat flows off like oil.-The shear-water petrel is smaller than the last. These birds are found in vast numbers in the Orkneys, where they are highly valued for their feathers as well as flesh.—The stormy petrel is of the size of a swallow, and rarely seen but at Sea; and in tempestuous weather numbers are observed following, as if for shelter, in the wakes of vessels. They dive sometimes for half an hour together, and live principally upon fish, but will eat a variety of offal thrown from ships.-In the Ferro Islands they are so astonishingly fat, that the natives are stated to use them as candles, after drawing a wick through their bodies. PROCESS, in Law, is the manner of proceeding in every cause, being the writs and precepts that proceed, or go forth, upon the original upon every action, being either civil or criminal. - . PROCLAMATION, a public notice given of any thing of which the king thinks proper to advertise his subjects. |PROCTOR, a person commissioned to manage another per- son's cause, in any court of the civil or ecclesiastical law. pKOCURATOR, a person who has a charge committed to him to act for another. - z PROCYON, a fixed star of the second magnitude in the constellation CANIs Minor. PROD, is a vessel used in the South Seas. This name, which signifies flying, it has obtained on account of the swift- ness with which it sails, being, with a brisk trade wind, near twenty miles an hour. It is chiefly used by pirates. . PRODUCING, in Geometry, signifies the drawing out a line farther till it has any assigned length , PRODUCT, in Arithmetic and Algebra, is the quantity arising from the multiplication of two or more factors together. | PROFILE, denotes the outline of a figure, building, member of architecture, &c. . . . . . PROFILE, in Sculpture and Painting, denotes a head, por- trait, &c. when represented sideways, or in a side view. PROGRESSION, an orderly advancing or proceeding in the same manner, course, tenor, proportion, &c. PROGRESSION, in Arithmetic and Algebra, a series of numbers advancing or proceeding in the same manner, or according to a certain law, &c.—Progression is either arith- metical, or geometrical. - - - Arithmetical PROGRESSION, is a series of three or more quan- tities that have all the same common difference; as 3, 5, 7, &c. which have the common difference 2; and a, a + d, a + 2 d, &c. which have all the same difference d. PROHIBITION, is a writ properly issuing only out of the Court of King’s Bench, being the king’s prerogative writ; but, for the furtherance of justice, it may now also be had in some cases out of the Court of Chancery, Common Pleas, or Exche- quer, directed to the judge and parties of a suit in an inferior court, commanding them to cease from the prosecution thereof, upon a suggestion, that either the cases originally, or some collateral matter arising therein, does not belong to that juris- dietion, but the cognizance of some other court. Upon the court being satisfied, that the matter alleged by the suggestion is sufficient, the writ of prohibition immediately issues. - PROJECTILES, are such bodies as, being put in a violent motion by any great force, are then cast off or let go from the place where they received their quantity of motion; as a stone thrown from a sling, an arrow from a bow, a bullet from a gun, &c. See GUNNERY. - PROJECTION, in Mechanics, the art of giving a body its projectile motion. See PRojectiles. PROJECTION, in Perspective, denotes the appearance or representation of an object on the perspective plane. See PERSPECTIVE. - - - PROJECTION of the Sphere in Plano, is a representation of the several points or places of the surface of the sphere, and of the circles described upon it, upon a transparent plane placed between the eye and the sphere, or such as they appear to the eye placed at a given distance. The principal use of the pro- jection of the sphere is in the construction of planispheres, maps, and charts, which are said to be of this or that projec- tion, according to the several situations of the eye, and the perspective plane, with regard to the meridians, parallels, and other points or places so represented. The most usual pro- jection of maps of the world, is that on the plane of the meri- dian, which exhibits a right sphere, the first meridian being the horizon. The next is that on the plane of the equator, which has the pole in the centre, and the meridians the radii of a cir- cle, &c. The projection of the sphere is usually divided into orthographic and stereographic ; to which may be added gnomonical. - Orthographic PRojection, is that in which the surface of the sphere is drawn upon a plane cutting it in the middle; the eye being placed at an infinite distance vertically to one of the hemispheres. Stereographic PRojection of the Sphere, is that in which the surface and circles of the sphere are drawn upon the plane of a great circle, the eye being in the pole of that circle. Gnomonical PROJECT to N of the Sphere, is that in which the surface of the sphere is drawn upon an external plane com- monly touching it, the eye being at the centre of the sphere. PROLATE, in Geometry, a term applied to a spheroid pro- duced by the revolution of a semi-ellipsis about its transverse diameter; and is thus distinguished from an oblate sphere, which is produced by the revolution of the ellipse about its conjugate diameter. PROMISE, is where, upon a valuable oonsideration, per- sons bind themselves by words to do or perform such a thing agreed on : it is in the nature of a verbal covenant, and wants only the solemnity of writing and sealing to make it absolutely the same. Yet for the breach of it, the remedy is different; for instead of an action of covenant, there lies only an action upon the case, the damages whereof are to be estimated and determined by the jury. - PROMONTORY, a high cape, or head-land. P R O fº R. O DICTIONARY of MECHANICAL SCIENCE, * 847 PRONOUN, in Grammar, a declinable part of speech, which being put instead of a noun, points out some person or thing. PiłóNUNCIATION, in Grammar, the manner of articulat- ing the words of a language. - fºr OOF, the shewing or making plain the truth of any mat- ter alleged; either in giving evidence to a jury on a trial, or else on interrogatories, or by copies of records, or exemplica- tions of them. - - PROPORTION, is often confounded with ratio; but they are quite different things. For, ratio is properly the relation of two magnitudes or quantities of one and the same kind; as the ratio of 4 to 8, or 15.to 30, or of 1 to 2, and so implies or respects only two terms or things. But proportion respects four terms or things, or two ratios which have each two terms; though the middle term may be common to both ratios, and then the proportion is expressed by three terms only, as 4, 8, 64, where 4 is to 8 as 8 to 64. proportion, in Mathematics, is an equality or simili- tude of ratio; thus, if the ratio a to b is the same as that of c - (? & e g to dº; that is, if: = . . then a, b, c, d, are in proportion, which is denoted by placing the quantities thus ; a + b : : a : b = c : d, and is read as a is to b, so is c to d. Proportion, though sometimes confounded with ratio, differs from it in this, that ratio has only a relation to two quantities of the same kind, whereas proportion relates to the comparison of two such ratios.-Proportion differs also from progression in this, that in the former it is only required that there should be an equality between the ratio of the 1st and 2nd term, and that of the 3d and 4th; whereas to constitute a progression there must be the same ratio between each two adjacent terms: these two cases, however, are sometimes dis. tinguished by the terms discrete and continued proportion. PRopoRtion, is also direct and inverse, or reciprocal, alter- mate, &c. Thus if the ratio of a to b is equal to the ratig c to d, then, c : d, or direct ........ . . . . . . . . . . . . . a b : ; c : d inversion . . . . . . . . . . . . . . . . . . b : a d : c alternate . . . . . . . . . . . . . . . . . . a : c : : b : d composition. . . . . . a + b : b : : c + d : d conversion ....... a + b : a : c + d : c division }: - ; ; ; ; ; ; L e e e s e e º e - a — b : b : c – d : d PRoportion, is again distinguished into arithmetical, geo- metrical, and harmonical. - Arithmetical PRoportion, is the equality of two arithmetical ratios or differences. As in the numbers 12, 9, 6; where the difference between 12 and 9, is the same as the difference be- tween 9 and 6, viz. 3. And here the sum of the extreme terms is equal to the sum of the means, or to double the single mean when there is but one. As 12 + 6 E 9 + 9 = 18. Geometrical PRoPortion, is the equality between two geo- metrical ratios, or between the quotients of the terms. See the preceding article. Harmonical PRopoRtion, is when the first term is to, the third, as the difference between the 1st and 2d is to the differ- ence between the 2d and 3d ; or in four terms when the 1st is to the 4th, as the difference between the 1st and 2d is to the difference between the 3d and 4th ; or the reciprocals of an arithmetical proportion are in harmonical proportion. As 6, 4, 3; because 6 : 3 :: 6 — 4 = 2 : 4 — 3 = 1; or be- cause }, +, , are in arithmetical proportion, making k + 4 = } + + = }. Also the four 24, 16, 12, 9, are in harmonical pro- portion, because 24 : 9 : : 8 : 3. Compass of PRoPortion, a name by which the French, and some English authors, call the sector. PROPORTIONAL, relating to proportion, as proportional compasses, parts, scales, spiral, &c. for which see the respective terms. PRoPortionAL, also denotes one of the terms of a propor- tion, which receives particular denominations according to the place it holds in the proportion, as a mean proportional, a third, fourth, &c. proportional. *. - Mean PRoPo Rtion AL, is the middle term of three continued geometrical proportionals. See MEAN Proportional. . Fourth ProportionAL, is the fourth term of a geometrical | proportion, which is found arithmetically by dividing the pro- duct of the second and third terms by the first. - To find a fourth Proportional to three given Lines, A, B, C.-- - •º. From any point D |H 2. draw two lines, mak- --—*— I? .ing any angle G D H. —”— a' In these lines take - C 2^ - D F equal to the first i ID & term A, DE equal to the second B, and DH equal to the third C. Join FE, and draw H G parallel to it, and D G will be the fourth proportional required. That is, D F (A) : D E (B): : D H (C) : D G. Third PROPoſtTIONAL, is the third of three terms in con- tinued proportion, and is found arithmetically by dividing the square of the second term by the first. To find a third Proportional to two yiven Lines, A and B.- - - From any point C i. - G_- draw two right lines, JE. making an angle FC G. A. In these lines take C E B - \ equal to the first term —- C TD it A, and C G, C D, each - equal to the second term B. Join E D, and draw G F parallel to it; and C F will be the third proportional required. That is, C E (A) : E G (B): : C D (B) ; C F. A. . . To cut a Line in eatreme and mean Propor- tion ; that is, so that the whole line may be to º greater part, as the greater part is to the €SS. Let A B be the given line, and draw BC E perpendicular to it and equal to half of it. From the centre C with radius C B describe is the circle DBF; join A C, and with AD as radius and A as a centre, describe the arc T} E cutting A B in E, so shall the line A B be divided in extreme and mean proportion in the point E. PROPOSITION, in Logic, part of an argument wherein some quality, either negative or positive, is attributed to a subject. - PROPOSITION, in Mathematics, is either some truth advanced, which is to be demonstrated, or some operation proposed, which is to be performed and shown to be that which was required. Being, in the former case, called a theorem, and in the latter a problem. - PROSODY, that part of Grammar which treats of the quan- tities and accents of syllables, and the manner of making verses. PROSOPOPCEIA, a figure in Rhetoric, whereby we raise qualities, or things in animate, into persons. C PROSTH APPHERESIS, is the same as the EQUATION of the €71t)'e. PROSTYLE, in ancient Architecture, a range of columns in front of n temple. - PROTEST, when one openly affirms, that he does either not at all, or but conditionally, yield his consent to any act, or unto the proceeding of a judge in court wherein his jurisdiction is doubtful, or to answer upon his oath any farther than by law he is bound. - - PRot Est, is also that act by which the holder of a bill o exchange declares, that such bill is dishonoured, - PROTEST, in naval language, an instrument drawn up in writing, and attested before a justice of the peace (or a consul or vice-consul in foreign parts,) by the master of a merchant- ship and a part of the ship's crew, after the expiration of a voyage, describing the severity of the voyage, whereby the ship has suffered, or may suffer, in her hull, rigging, or cargo. It is chiefly intended to shew that such damages did not happen through any negleet or misconduct of the master or his officers, &c. - PROTESTANT, a name first given in Germany to those who adhered to the doctrine of Luther; because in 1629 they pro- tested against a decree of the emperor Charles V. and the diet of Spires; declaring, that they appealed to a general council. E" $48 P R U P R U DICTIONARY OF MECHANICAL SCIENCE The same name also has been given to those of the sentiments of Calvin, and is now become a common denomination for all those of the reformed churches. . . PROTHONOTARY, a term which properly signifies first notary, and which was anciently the title of the principal nota- ries of the emperors of Constantinople. Prothonotary with us is used for an officer in the Courts of King’s Bench and Com- mon Pleas; the former of which courts has one, and the latter three. The prothonotary of the King's Bench records all civil actions sued in that court, as the clerk of the crown-office does all criminal causes. The prothonotaries of the Common Pleas enter and enrol all declarations, pleadings, assizes, judgments, and actions; they also make out all judicial writs, except writs of habeas-corpus, and distringas jurator, for which there is a particular office, called the habeas corpora office; they likewise enter recognizances acknowledged, and all common recoveries; make exemplification of records, &c. - PROTOXIDE, in Chemistry, a term used to denote the minimum of oxidizement. s * , PROTRACTION, the same with plotting. PROTRACTOR, is the name of an instrument used for protracting or laying down on paper the angles of a field or other figure. The protractor is a small semicircle of brass, or other solid matter, the limb or circumference of which is nicely divided into one hundred and eighty degrees; it serves not only to draw angles on paper, or any plane, but also to exa- mine the extent of those already laid down. For this last pur- pose let the small point in the centre of the protractor be placed above the angular point, and make the side coincide with one of the sides that contain the angle proposed; then the number of degrees cut off by the other side, computing on the protractor, will shew the quantity of the angle that was to be measured. Protractors are now more usually made in the form of a parallelogram, and properly graduated at the upper edge. - PROVIDENCE, the conduct and direction of the several parts of the universe, by a superior intelligent Being. PROVINCE, the circuit of an archbishop’s jurisdiction. PROVISO, in Law, a condition inserted in a deed, upon the observance whereof the validity of the deed depends. PROVOST, an officer, whereof there are divers kinds, civil, military, &c. PRovost of a city or town, is the chief municipal magistrate in several trading cities, particularly in Scotland, being the same with mayor in England. PRovost Marshal of an Army, is an officer appointed to seize and secure deserters, and all other criminals. He is to hinder soldiers from pillaging, to indict offenders, and to see the sen- tence passed on them executed. He also regulates the weights and measures, and the price of provisions, &c. in the army. PROVOST-MARSHAL, an officer appointed to take charge of prisoners at a court-martial. PROW, a name given by seamen to the beak or pointed cut- water of a xebec, galley, or polacre. The upper part of the prow is usually furnished with a grating platform for the con- venience of the seamen, who walk out to perform whatever is necessary about the sails or rigging on the bowsprit. PRUNELLA VULGAR1s. (Selfheal.) The leaves have an herbaceous roughish taste, and hence stand recommended in haemorrhages and alvine fluxes. It has been principally cele- brated as a vulnerary, whence its name ; and in gargarisms for aphthae and inflammations of the fauces. PRUNELLAE, SAL, a preparation of purified saltpetre. PRUNES, are plums dried in the sunshine, or in an oven: PRUNING, in Gardening and Agriculture, is the lopping off the superfluous branches of trees, in order to make them bear better fruit, grow higher, or appear more regular. Pruning, though an operation of very general use, is nevertheless rightly understood by few ; nor can it be learned by rote, or, indeed, wholly by books, but requires a strict observation of the dif- ferent manners of growth of the several sorts of fruit trees; the proper method of doing which cannot be known, without care- fully observing how each kind is naturally disposed to produce its fruit; for some do this on the same year's wood as wines; others, for the most part, upon the former year’s wood, as peaches, nectarines, &c. and others, upon spurs which are produced upon wood of three, four, &c. to fifteen or twenty years' old, as pears, plums, cherries, &c. therefore, in order to the right management of fruit trees, provision should always be made, to have a sufficient quantity of bearing wood in every part of the trees, and at the same time there should not be a superfluity of useless branches, which would exhaust the strength of the trees, and cause them to decay in a few years. The reasons for pruning of fruit trees are, 1. To preserve them longer in a vigorous bearing state : 2. To render them more beautiful: , and; 3. To cause the fruit to be larger and better tasted. PRUNUS, a genus of the monogynia order, in the inco- sandria class of plants; and in the natural method ranking under the 36th order pomaceae. There are thirty-three species. PRUNUs DomesticA. (The Common Plum Tree.) The me- dical effects of the damson and common prunes are, to abate heat, and gently loosen the belly; which they perform by lubri- cating the passage, and softening the excrement. They are of considerable service in costiveness accompanied with heat or irritation, which the more stimulating cathartics would tend to aggravate : where prunes are not of themselves sufficient, their effects may be promoted by joining with them a little rhubarb or the like ; to which may be added some carmina- tive ingredient, to prevent their occasioning flatulencies. Pru- nelloes have scarce any laxative quality; these are mild, grateful refrigerants, and by being occasionally kept in the mouth, usefully allay the thirst of hydropic persons. PRUNUs Lauro-cerasus. (The Common Laurel.) The leaves of the laurel have a bitter taste, with a flavour resembling that of the kernels of the peach or apricot; they communicate an agreeable flavour to aqueous and spirituous fluids, either by infusion or distillation. The distilled water applied to the organs of smelling strongly impresses the mind with the same ideas as arise from the taste of peach blossoms or apricot kernels: it is so extremely deleterious in its nature, and some- times so sudden in its operation, as to occasion instantaneous death; but it more frequently happens that epileptic symptoms are first produced. This poison was discovered by accident in Ireland in the year 1728; before which, it was no uncommon practice there, to add a certain quantity of laurel water to brandy, or other spirituous liquors, to render them agreeable to the palate. At that time three women drank some laurel- water; and one of them a short time afterwards became vio- lently disordered, lost her speech, and died in about an hour. A gentleman at Guildford, some few years back, also, by mak- ing an experiment as he intended on himself, was poisoned by a small dose : he did not survive the taking it more than two hours. In consequence of the above poisonous principle exist- ing in the laurel, it has been recommended to persons to be cautious how they make use of the leaves of that shrub, which is a usual practice with cooks for giving flavour to custards, blanch-mange, and other made-dishes, lest the narcotic prin- ciple should be also conveyed, to the detriment of the health of persons who eat of them. And the same may be said of the kernels of all stone-fruits; for the flavours given to noyau, ratafia, and other liquors which are highly prized by epicures, are all of them derived from the same principle as laurel-water, and which, on chemical investigation, is found to be prussic acid. This exists in considerable quantities in the bitter almond, and which when separated proves to be the most active poison known, to the human as well as all other animal existence. This principle, and its mode of extraction, should be made equally as public as the necessity of scientific re- searches requires. We cannot with propriety accuse either this tree or the laurel as being poisonous, because the inge- nuity of mankind has found out a mode of extracting this active acidulous principle, and which is so very small in pro- portion to the wholesome properties of the fruit, as not to be suspected of any danger but for this discovery. As well might we accuse wheat of being poisonous, because it yields on dis- tillation brandy, which has been known to kill many a strong- bodied fellow who has indulged in this favourite beverage to excess. An eminent chemist observes, that he has made experiments with the oxalic acid, and found that when this was also concentrated, it has similar effects; insomuch that no animal can contain a grain of it if taken into the throat or sto- P. S I P U L 849 DICTIONARY OF MECHANICAL SCIENCE. mach: and thus might we also be led to consider the clegant, and in itself harmless, wood-sorrel, as a poisonous plant. PRUSSIC Acid, in Chemistry and the Arts, is one of the most important of the acids. about the beginning of the last century by Diesbach, a chemist of Berlin. This gentleman wishing to precipitate a decoction of cochineal with an alkali, got some potash, on which he had distilled for several times his animal oil, and as there was some sulphate of iron in the decoction, the liquor instantly exhibited a beautiful blue in the place of a red precipitate. Hence he saw the method of producing the same substance at pleasure, and it soon became an object of commerce, and obtained the name of Prussian blue, from the place where it was discovered. This substance is now formed chiefly during the decomposition of animal substances in high temperatures. Three parts of blood, evaporated to dry- ness in an iron dish, are to be mixed with one part of sub- carbonate of potash (common pearlash), and calcined in a crucible, which should be only two-thirds filled by the ma- terials, and covered with a lid. The calcination must be continued with a moderate heat as long as the flame issues from the crucible; and when it becomes faint, and likely to be extinguished, the process must be stopped. Throw the mass when cold, into ten or twelve parts of water; allow it to soak a few hours, and then boil them together in an iron kettle. Filter the liquor, and continue pouring hot water on the mass as long as it acquires any taste. To this solution add one composed of two parts of alum and one of sulphate of iron in eight or ten of boiling water, and continue the mixture as long as any effervescence and precipitation ensues. Wash the precipitate several times with boiling water. It will have a green colour; but on the addition of a quantity of muriatic acid, equal to twice that of the sulphate of iron which has been used, it will assume a beautiful blue colour. Wash it again with water, and dry it in a gentle heat. In this state it is the pigment, called Prussian blue, which consists of a mixture of prussiate of iron with alumine. From prussiate of "iron, the prussic acid may be separated by the following process: mix two ounces of red oxide of mercury, prepared by nitric acid, with four ounce of finely powdered Prussian blue, and boil the mixture with twelve ounces of water in a glass vessel, shaking frequently. Filter the solution, which is a prussiate of mercury, while hot, and when cool add to it in a bottle two ounces of iron filings, and six or seven drachms of sulphuric acid ; shake these together, decant the clear liquor into a rectort, and dis- till off one-fourth of the liquor. The distilled liquor is the prussic acid, which combines with alkalies and earths, and has many of the properties belonging to the other acids. It has a sweetish taste, and a smell resembling that of bitter almonds: it does not redden blue vegetable colours. It precipitates sul- phurets, and curdles soap. It separates allumine from nitric acid. Oxygenized muriatic acid entirely decomposes it. It does not appear to have a strong affinity for alkalies, nor does it take them from carbonic acid, for no effervescence arises on adding it to a solution of alkaline carbonates; on the contrary, its combinations with alkalies and earths are decomposed by exposure to carbonic acid, even when highly diluted, as in atmospheric air. It readily combines, however, with pure alkalies, destroys their alkaline properties, and forms crystalliz- able salts. It does not precipitate iron blue, but green, and this green precipitate is soluble in acids. The rays of light render the green precipitate blue, as does also the addition of metallic iron, or sulphurous acid.) PRUSSIAN BLUE. See PRUssic AcID. PRYTANEUM, in Grecian Antiquity, a large building in Athens, where the council of the prytanes or presidents of the senate assembled, and where those who had rendered any sig- nal service were maintained at the public expense. PSALTERIUM GEORGII, the Harp of George, is a new constellation, introduced by one of the German astronomers, in honour of his late Britannic Magesty George III. It is bounded on the north by Taurus, on the east by Sceptrum Brandenbur- "gium, on the south by Eridanus, and on the west by Cetus. PSITTACUS, or PARRot, a genus belonging to the order of pica. The bill in this genus is hooked from the base: and | the upper mandible is moveable; the nostrils are round, placed It was discovered by accident. in the base of the bill, which in some species is furnished with a kind of cere; the tongue is broad, and blunt at one end ; the head is large, and the crown flat ; the legs are short, the toes placed two before and two behind. These abound within the tropics, and live on seeds and fruit, in their natural state, but in confinement will eat both flesh and fish. They often appear in flocks, yet are in such cases generally somewhat separated into pairs. They are noisy, mimetic, singularly capable of arti- culating human sounds, extremely docile, and long lived. They breed in the hollows of trees, without constructing any nest, and use their feet as hands to convey food to their mouths. Latham notices one hundred and thirty three species, and Gmelin no fewer than one hundred and sixty-nine. The general division is regulated by the evenness or unevenness of the tails. PTOLEMAIC, or Ptolemean System of Astronomy, is that invented by Claudius Ptolemaeus, a celebrated astronomer and mathematician of Pelusium in Egypt, who lived in the beginning of the second century of the Christian aera. This hypothesis supposes the earth immoveably fixed in the centre, of the universe ; and that the sun, the moon, the planets, and stars, all move about it from east to west, once in twenty-four hours, in the order following, viz, the Moon next to the Earth, then Mercury, Venus, the Sun, Mars, Jupiter, Saturn, the fixed stars, the first and second crystalline heavens, and, above all, the fiction of their primum mobile. PUDDING, a sea term, or PUDDENING, a thick wreath or circle of cordage, tapering from the middle towards the ends, pointed all over, and fastened about the main or fore masts of a ship, directly below the trusses, to prevent the yards from falling down, when the ropes by which they are usually sus- pended are shot away in battle. Puddening is also sometimes ornamental works. placed on a boat's stem as a kind of fender. PUDDING Stone, in Chemistry, a term invented by English lapidaries to designate one particular mineral aggregate, con- sisting of oblong and rounded pebbles of flint, about the size of almonds, imbedded in a hard siliceous cement. The pebbles are usually black, and the cement of a light yellowish brown. It is capable of receiving a very high polish, and is used in It is found chiefly in Essex. The French mineralogists have naturalized the term poudingue, and have applied it to all rounded stones imbedded in a cement, so as to make it nearly synonymous to the English “rubble-stone.” PULEX, the Flea, a genus of insects of the order aptera. PULLEY, one of the simple machines, or, as they are com- monly called, mechanical powers; its theory is laid down under Mech AN1cs. The present article is introduced for the pur- pose of mentioning some ingenious practical combinations of pulleys, in addition to those already exhibited. The usual methods of arranging pulleys in their blocks may be reduced to two. The first consists in placing them one by the side of another upon the same pin : the other, in placing them directly under one another upon separate pins. Rach of these methods, however, is liable to inconvenience; and Mr. Smeaton, to avoid the impediments to which these combinations are subject, pro- poses to combine these two methods in one. A very consider- able improvement in the construction of pulleys has been made by James White, who obtained a patent for his invention, of which he gives the following description.—The annexed figure shews the machine, consisting of two pul- leys, Q and R, one fixed and the other moveable. Each of these has six concen- º tric grooves capable of having a line put AR round them, and thus acting like as many different pulleys, having diameters equal #|S to those of the grooves. Supposing then E. cach. of the grooves to be a distinct pulley, and that all their diameters were equal, it is evident that if the weight 144 were to be raised by pulling, at S till the pulleys touch each other, the first pulley must re- ceive the length of line as many times as there are parts of the line hanging between it and the lower pulley. In the present case there are twelve lines b, d, f, &c. hanging between the two pulleys, formed by its revolution about the six upper and É # * sº- º sº 5 É E. # º - ſºº g-º § : w & º gºſº º :GE. ~.;# | *:5.& g- Weſſº” Nºli.) // 10 G 850 P U M P U M DICTIONARY OF MECHANICAL SCIENCE. lower grooves. Hence, as much line must pass over the upper- most pulley as is equal to twelve times the distance of the two. But, from an inspection of the figure, it is plain that the second pulley cannot receive the full quantity of line by as much as is equal to the distance betwixt it and the first. In like man- ner, the third pulley receives less than the first by as much as is the distance between the first and third ; and so on to the last, which receives only one-twelfth of the whole: for this receives its share of line n from a fixed point in the upper frame, which gives it nothing; while all the others in the same frame receive the line partly by turning to meet it, and partly by the line coming to meet them. Supposing now these pul- leys to be equal in size, and to move freely as the line deter- | mines them, it appears evident, from the nature of the system,' that the number of their revolutions, and consequently their velocities, must be in proportion to the number of suspending | parts that are between the fixed point above mentioned, and each pulley respectively. Thus the outermost pulley would go twelve times round in the time that the pulley under which the part n of the line, if equal to it, would revolve only once ; and the intermediate times and velocities would be a series of arithmetical proportionals, of which, if the first number were 1, the last would always be equal to the whole number of terms. Since then the revolutions of equal and distinct pulleys are measured by their velocities, and that it is possible to find any proportion of velocity on a single body running on a centre, | viz. by finding proportionate distances from that centre; it follows, that if the diameters of certain grooves in the same substance be exactly adapted to the above series, (the line itself being supposed inelastic, and of no magnitude,) the necessity of using several pulleys in each frame will be obvi- ated, and with that some of the inconveniences to which the use of the pulley is liable. In the figure referred to, the coils of rope by which the weight is supported are represented by the lines a, b, c, &c. : a is the line of traction, commonly called the fall, which passes over and under the proper grooves, until it is fastened to the upper frame just above n. In practice, however, the grooves are not arithmetical proportionals, nor can they be so; for the diameter of the rope employed must in all cases be deducted from each term ; without which the smaller grooves, to which the said diameter bears a larger pro- portion than to the larger ones, will tend to rise and fall faster than threy, and thus introduce worse defects than those which they were intended to obviate. The principal advantage of this kind of pulley is, that it destroys lateral friction, and that kind of shaking motion which is so inconvenient in the com- mon pulley. These pulleys, when well executed, apply to iacks and other machines of that nature with peculiar advan- tage, both as to the time of going and their own durability; and it is possible to produce a system of pulleys of this kind of six | or eight parts only, and adapted to the pocket, which, by means of a skain of sewing silk, or a clue of common thread, will raise upwards of a hundred weight. The friction of the pulley is now reduced to almost nothing by Mr. Garnett's ingenious patent friction-rollers, which produce a great saving of labour and expense, as well as in the wear of the machine, both when applied to pulleys and to the axles of wheel- carriages. His general principle is this ; between the axle and nave, or centre pin and box, a hollow space is left, to be filled up by solid equal rollers nearly touching each other. These are furnished with axles inserted into a circular ring at each end, by which their relative distances are preserved ; and they are kept parallel by means of wires fastened to the rings between the rollers, and which are riveted to them. PULO, is a general term for island on the coasts of Siam and the island of Sumatra, in the East Indies, and in the East- ern Indian Ocean. PULSE, in the animal economy, denotes the beating or throbbing of the heart and arteries. PUMICE STONE, or porous glasses. When the compact glasses are exposed to the heat of our furnaces, they emit a great number of air bubbles, which render them porous; such is the origin of pumice. It has the same base as compact glass. The texture is fibrous: the fibres have a silky lustre. Colours various ; white, brown, yellow, black. Before the blow-pipe, they melt into a white enamel. PUMP, a hydraulic machine for raising water by the pres- sure of the atmosphere. The most important and certain part of the theory of pumps has been laid down in the construction of two or three kinds which have been already described in this. work, under the articles Centrl FUGAL MACHINE, FIRE-ENGINE, ForceR, and HYDRAULics. A few other useful, yet not com- plex, pumps, will be described in the present article; and some account will be added of the most ingenious pistons and valves. A modification of the sucking-pump which has been much recommended, is exhibited in the annexed figure. Here the - suction-pipe C O comes up through a cistern KM N L deeper or longer than the intended stroke of the piston, and has a valve C at top. The piston, or what acts in lieu of it, is a tube A H G B, open at both ends, and of a diameter somewhat larger than that of the suction- pipe. The interval between them is filled up at H G by a ring or belt of soft lea- ther, which is fastened to the outer tube, and moves up and down with it, sliding along the smoothly polished surface of the suction-pipe with very little friction. There is a valve I on the top of this pis- ton, opening upwards. Water is poured into the outer cistern. The outer cylin- der or piston being drawn up from the bottom, there is a great rarefaction of the air which was between them, and the atmo- sphere presses the water up through the suction-pipe to a cer- tain height; for the valve I keeps shut by the pressure of the atmosphere and its own weight. Pushing down the piston causes the air, which had expanded from the suction-pipe into the piston, to escape through the valve I: drawing it up a second time allows the atmosphere to press more water into the suction-pipe, to fill it, and also part of the piston. When this is pushed down again, the water which had come through the valve C is now forced out through the valve I into the cistern K M N L, and now the whole is full of water. When, therefore, the piston is drawn up, the water follows, and fills it, if not thirty-three feet above the water in the cistern ; and when it is pushed down again, the water which filled the piston is all thrown out into the cistern ; and after this it delivers its full contents of water every stroke. The water in the cistern K M N L effectually prevents the entrance of any air between the two pipes; so that a very moderate compression of the belt of soft leather at the mouth of the piston cylinder is sufficient to make all perfectly tight. If a pump absolutely without friction be wanted, the fol- lowing seems preferable for simplicity and performance to any we have seen, when made use of in proper situations. Let N O, in the figure, be the surface of the water in the pit, and K the place of delivery. The pit must be as deep in water as from K to N O. A B C D is a wooden trunk, round or square, open at both ends, and having a valve P at the bottom. The top of this trunk must be on a level with K, and has a small cistern E A D F. It also com- municates laterally with a rising pipe G H K, furnished with a valve at H opening upwards. LM is a beam of timber so fitted to the trunk as to fill it without sticking, and is of at least equal length. It hangs by a chain from a working beam, and is loaded on the top with weights exceeding. that of the column of water which it displaces. Now suppose this beam allowed to descend from the position in which it is drawn in the figure ; the water must rise all round it, in theº crevice which is between it and the trunk, and also in the rising pipe; be- cause the valve P shuts, and H opens; so that when the plunger has got to the bottom, the water will P U M SCIENCE. P U M 851 DICTIONARY OF MECHANICAL !. Wºº stand at the level of K. When the plunger is again drawn up to the top by the action of the moving power, the water sinks again in the trunk, but not in the rising pipe, because it is stopped by the valve H, Then allowing the plunger to descend again, the water must again rise in the trunk to the level of K, and it must now flow out at K; and the quantity discharged will be equal to the part of the beam below the surface of the pit-water, deducting the quantity which fills the small space between the beam and the trunk. This quantity may be re- duced almost to nothing, for if the inside of the trunk and the outside of the beam be made tapering, the beam may be let down till they exactly fit; and as this may be done in square work, a good workman can make it exceedingly accurate. But in this case, the lower half of the beam and trunk must not taper; and this part of the trunk must be of sufficient width round the beam to allow free passage into the rising pipe. Or, which is better, the rising pipe must branch off from the bot- tom of the trunk. A discharge may be made from the cistern B. A D F, so that as little water as possible may descend along the trunk when the piston is raised. There can be no doubt, that the above is a very ingenious contrivance, and that it fully answers every purpose to which it can be rendered applicable. Indeed, it may be asserted with safety, that among the numerous ramifications into which mechanism and the mechanic arts have been extended, scarcely any branch furnishes a greater variety than may be found in pump machinery. Under this article many combinations of power are presented to the reader; but several others, equally deserving of attention, are left unnoticed, lest the whole should become too extended. We have endeavoured to select from the field of diversity such specimens, as display in the powers of invention the greatest portion of originality. Among these, pumps that are constructed to accomplish the desired end, either without friction, or with its aggregate greatly diminished, imperiously claim an admission into the pages of our Scientific miscellany. - - The most ingenious contrivance of a pump without friction is that of Haskins, described in Phil. Trans. No. 370, and called by him the Quicksilver Pump. Its construction and mode of operation are complicated; but the following preliminary obser- vations will, we hope render them abundantly plain. Let there be (see fig.) a cylindrical iron • pipe, about six feet long, open at top ; also another cylinder, connected with it at bottom, and of smaller diameter. It may either be solid, or, if hollow, it must be close at top. Let a third iron cylinder, of an intermediate diameter, be made to move up and down between the other two without touching either, but with as little interval as possible. This middle cylin- der communicates by means of the pipe A B, with the upright pipe F E, having valves C and D (both opening upwards) Q adjoining to the pipe of communication. Suppose the outer cylinder suspended by chains from the end of a working beam, and let mercury be poured into the inter- val between the three cylinders till it fills N the space to about three-fourths of their =# 8 height. Also suppose that the lower end of the pipe FE is immersed into a cistern of water, and that the valve D is less than 33 feet above the surface of this water. Now, suppose a perforation made somewhere in the pipe A B, and a communication made with an air-pump. When the air-pump is worked, the air contained in CE, in A B, and in the space between the inner and middle cylinders, is rarified, and is abstracted by the air-pump ; for the valve D imme- diately shuts. water to rise in the pipe C E, and will cause the mercury to rise between the inner and middle cylinders, and sink between the outer and middle cylinders. Let us suppose mercury 12 times heavier than water; then for every foot that the water rises in E C, the level between the outside and inside mercury will vary an inch : and if we suppose D E to be 30 feet IE *-*. E then if we can rarefy the air so as to raise the water to D The pressure of the atmosphere will cause the the outside mercury will be depressed to q and r, and the inside mercury will have risen to s, t, s q, and t r, being about 30 inches. In this state of things, the water will run over by the pipe B.A., and every thing will remain nearly in this position. The columns of water and mercury balance each other, and balance the pressure of the atmosphere. While things are in this state of equilibrium, if we allow the cylinders to descend a little, the water will rise in the pipe FE, which we may now consider as a suction pipe; for by his motion the capacity of the whole is enlarged, and therefore the pressure of the atmosphere will still keep it full, and the situation of the mercury will again bo be in equilibrio. It will be a little lower in the inside space, and higher in the outside. - - Taking this view of things, we see clearly how the water is supported by the atmosphere at a very considerable height. The apparatus is analogous to a syphon which has one leg filled with water and the other with mercury. But it was not neces- sary to employ an air-pump to fill it. Suppose it again empty, and all the valves shut by their own weight. Let the cylinders descend a little. The capacity of the spaces below the valve D is enlarged, and therefore the included air is rarefied, and some of the air in the pipe C E must diffuse itself into the space quit- ted by the inner cylinder. Therefore the atmosphere will press some water up the pipe FE, and some mercury into the inner space between the cylinders. When the cylinders are raised again, the air which came from the pipe C E would return into it again, but is prevented by the valve C. Raising the cylin- ders to their former height would compress this air; it there- fore lifts the valve D, and escapes. Another depression of the cylinders will have a similar effect. The water will rise higher in FC, and the mercury in the inner space; and then after repeated strokes the water will pass the valve C, and fill the whole apparatus, as the air-pump had caused it to do before. R The position of the cylinders when things are in \ this situation is represented in this figure, the A outer and inner cylinder in their lowest position having descended about 30 inches. The mercury in the outer space stands at q r, a little above the middle of the cylinders, and the mercury in the inner space is near the top t s of the inner cylin- der. Now let the cylinders be drawn up. The water above the mercury cannot get back again through the valve C, which shuts by its own weight. We therefore attempt to compress it; but the mercury yields, and descends in the inner space, and rises in the outer till both are quickly on a level, about the height vu. If we continue to raise the cylinders, the eompression forces out more mercury, and it now stands lower in the in- ner than in the outer space. But that there may be something to balance this inequality of the mercurial columns, the water goes through the valve D, and the equilibrium is restored when the height of the water in the pipe E D above the surface of the internal mercury is twelve times the difference of the mercurial columns (on the former supposition of specific gravity). If the quantity of water be such as to rise two feet in the pipe E D, the mercury in the outer space will be two inches higher than that in the inner space. Another depression of the cylinders will again enlarge the space within the apparatus, the mercury will take the position of the last figure, and more water will come in. Raising the cylinders will send this water four feet up the pipe E D, and the mercury will be four inches higher in the inner than in the outer space. Repeating this operation, the water will be raised still higher in D E; and this will go on till the mercury in the outer space reaches the top of the cylinder; and this is the limit of the performance. The dimensions with which we set out will enable the machine to raise the water about 30 feet in the pipe E D ; which, added to the 30 feet of CF, makes the whole height above the pit water 60 feet. By making the cylinders longer we increase the height of FD. This machine must be worked with great attention, and but slowly; for at the begin- ning of the forcing stroke the mercury very rapidly sinks in the inner space and rises in the outer, and will dash out and be lost. To prevent this as much as possible, the outer cylinder terminates in a sort of cup or dish, and the inner cylinder should be tapered at the top. - 852 P U M P U M. DICTIONARY OF MECHANICAL SCIENCE. A Quicksilver Pump has been lately contrived by a Mr. Clarke of Edinburgh, for the purpose of raising water without friction, and in its construction is essentially different from that of Mr. Haskins, having great power in drawing and forcing water to any height, and possessing extreme simplicity in its construc- tion. - * - - a a is the main pipe in- serted into the well b ; a. valve is situated at c, and another at d, both opening upwards; a piece of iron tube is then bent into a circular form, as at f again turned off at g in an angu- lar direction, so as to pass through a stuffing box at h, and from thence bent outwards as at i, connect- ing itself with the ring. A quantity of quicksilver is then put into the ring fill- ing it from q to q, and the ring being made to vibrate upon its axis h, a vacuum is effected in the main pipe by the recession of the mercury from g to i, thereby causing the water to rise and fill the vacuum ; upon the motion being re- rº" . . ºr versed, the quicksilver w-. slides back to g, forces up the water, and expels it at the spout e. Mr. Clark calculates that a pump of this description with a ring twelve feet in diameter, will raise water the same height E---> = E- -i .# * as the common lifting pump, and force it one hundred and fifty feet higher without any friction. The following pump, without friction, may be constructed in a variety of ways by any common carpenter, without the assist- ance of the pump-maker, or plumber, and will be very effective | for raising a great quantity of water to small heights, as in draining marshes, marl pits, quarries, &c, or even for the ser- | vice of a house. A B C D in this figure is a square trunk of carpenter’s work open at both ends, and having a little cistern and spout at top. Near the bottom there is a partition made of board, perforated with a hole E, and covered with a clack. ffff represent a long cylindrical bag made of leather or of double canvass, with a ſold of thin leather, such as sheep- skin, between the canvass bags. This is firmly nailed to the board E with soft leather between. The upper end of this bag is fixed on a round board having a hole and valve F. This board may be turned in the lathe with a groove round its edge, and the bag fastened to it by a cord bound tight round it. The fork of the piston rod FG is firmly fixed into this board; the bag is kept dis- tended by a number of wooden hoops or C rings of strong wire ffff, ff, &c. put into it at a few inches' distance from each other. * It will be proper to connect these hoops before putting them in, by three or four cords from top to bottom, which will keep them at their proper distances. lows powder-puff. The distance between the hoops should be about twice the breadth of the rim of the wooden ring to which the upper valve and piston rod are fixed. Now let this trunk be immersed in the water. It is evident that if the bag be stretched from the compressed form which its own weight will give it by drawing up the piston rod, its capacity will be enlarged, the valve F will be shut by its own weight, the air in the bag will be rarefied, and the atmosphere will press the water intº the bag. When the rod is thrust down again, this water will come out by the valve F, and fill part of the trunk. A re- Petition of the operation will have a similar effect; the trunk Thus will the bag have the form of a barber’s bell will be filled, and the water will atlast be discharged by the spout. —The same bag-piston may be employed for a forcing pump, by placing it below the partition, and inverting the valve; and it will then be equally strong, because the resistance in this case too will act by compression. Single Barrel Pump, with a Double Action.—An ingenious variation in the construction of the sucking pump, is that with two piston rods in the same barrel, invented by the late W. Taylor, of Southampton. A vertical section of this pump - is given in the figure. The piston rods have racks at their upper parts work- ing on the opposite sides of a pinion, and kept to their proper positions by , friction rollers. The valves used in this pump are of three kinds, as shewn at a, b, and c. The former is a spheric segment which slides up and down on the piston rod, and is brought down by its own weight: the second, b, is called the pendulum valve ; and the third, c, is a globe which is raised by the rising wa- ter, and falls again by its own weight. Each of these valves will disem- gage itself from chips, sand, gravel, &c. brought up by the water. In this kind of pump the pistons may either be put in mo- tion by a handle in the usual way, or a rope may pass round the wheel de in a proper groove, the two ends of which, after crossing at the lower part of the wheel, may be pull- - ed by one man or more, on each side.” A pump of this kind, with a seven-inch bore, heaves a ton twenty-four feet high in a minute, with ten men, five only working at a time on each side. Another improvement of the common pump has been made by Todd, of Hull. This invention, in some particulars, bears a resemblance to the ordinary one, but he has contrived to double its powers by the following means:—Having prepared the pis- ton cylinder, which may be twelve feet high, he cuts from the bottom thereof about three feet; at the end of the great cylin- der he places an atmospheric valve, and to the top of the small cylinder a serving valve. In the bottom of the small cylinder, which contains the serving valve, is inserted an oblong ellip- tical curved tube, of equal calibre with the principal cylinder, and the other end is again inserted in the top of the great cylin- der. This tube is divided in the same manner as the first cylinder, with atmospheric and serving valves, exactly parallel to the valves of the first cylinder. The pump, thus having double valves, produces double effects, which effects may be still further increased by extending the dimensions. This pump, in addition to its increased powers, possesses another very great and prominent advantage. By screwing to it the long leather tube and fire-pipe of the common engine, it is in a few minutes converted into an effective fire-engine. Hence, whoever possesses one, may be said to have a convenient domestic apparatus against fire. Three men can work it; one to turn the winch, another to direct the fire-pipe, and a third to supply the water. - The late Mr. Benjamin Martin invented a curious and power- ful pump with two pistons, the friction of which was exceed-e ingly small. An admirable engraving of this pump, by Lowry, is given in vol. xx. of Tilloch's Philosophical Magazine. The following is a plan of a Gold Mine Pump, which will supersede the necessity of cutting new shafts, to suit the wind- P U M P U M DICTIONARY OF MECHANICAL SCIENCE. 853 ings and various elevations and declinations of the mines. We have been informed, that in the gold and silver mines in South America, the rod pump is often rendered useless, from the want of some such contrivance Description.—r r represent a pipe that enters the well, and is supplied with water by means of the pressing weight of the atmosphere; B E B E are two working barrels; P P, the stand pipe ; C C C C are half-inch pipes filled with water; o o the work- ling beam; that acts on the pistons MN, that work on the half-inch pipes; a S S e are buckets; v v, evacuants. If any small quantity of water issue into the evacuants, the piston blocks, x x, force it back through the valves 5, 6; the numbers 1, 2, 3, 4, represent the four valves. Perhaps a rough calculation would be the best mode of elucidating the principle of this invention. Let us suppose the depth of the pipes C P to be 500 feet, the barrels four feet, and the pipe ºr r 16 feet; the diameter of the above to be 20 inches, except that 40f the pipes C C C C, which is half an inch. The weight of the water on the buckets e a, weighs 30 pounds; the § pressure on the buckets S S is equal to 1500 pounds each ; so that, at the rising of the piston M, the pressure of the atmo- sphere, 1500 pounds, will force the bucket S e up, so that the water will keep rising with the piston M, at the same time the piston N will be forcing the water downwards. The water will, in consequence, force the bucket a, so that the water in the barrel is forced out through the valve 3, into the pipe PP, and out at W. Now, it is easily to be perceived, that an evacua- tion will be created at v ; that afterwards the piston N will be raised, and the effect will be as described of M, and the effect on M as described of N, and so on alternately, so that a con- tinual stream will flow out at W. The pressure of 1500 pounds is produced in consequence of the buckets S S being 20 feet from the level of the water; so that there is left five pounds on the square inch, which multiplied by 300 inches, the area of the bucket, gives 1500 pounds.-The advantage of this pump is evident, as, whatever the winding of the mines might be, the pipe of such a pump might be turned accordingly, without any obstruction to the pump, and all the expense of cutting new shafts would thus be saved. The annexed figure represents a Pump, described by M. Ozanam in his Récréations Mathématiques et Physiques, which appears superior to the pumps now in use. Its"action and construction may be easily understood by the figure. A is the working cylinder; B, the piston, or plunger, the rod of which, D, works in an air-tight manner, through the stuffing box C. E is the suction pipe, or pipe leading from the well; and H, the discharging pipe. FF and G G are valves, all opening upwards. The piston is repre- sented as ascending, and therefore the valves at FF are open, and at G G shut. I is the plate closing the bottom of the cy- linder, and by which the whole may be securely bolted down to the work support- ing it. It will easily be seen, that this pump \m Hål, raises water both in the ascending and \# àF descending stroke of the piston, and there- I ſº fore affords a continued stream of water. & Pumps with double action have been in | use some time, but the one now described is - i. simple and powerful than those on the usual construc- 1011. - k Double Atmospheric Pump.—This figure represents a pump for raising water from wells between 50 and 60 feet in depth, to º, yoked merely by a lever, Let A represent a cylinder fastened to the iron rod or Spear. three feet in diameter, and 30 in length, reaching below the surface . of the water in the well, furnished with an aperture B at the top, C a cylinder about eight inches in dia- meter, with an aperture at D. Let E represent an air-tight valve, alter- nately to open and close the two apertures B and D. F., a valve that will open and close itself by the pressure of the atmosphere. G, the handle to be used by the operator for opening and closing the aper- tures B and D. When we wish to work the pump, the aperture B must, in the first in- stance, be closed, and D of course will remain open, to allow the whole of the air in the large cylinder to ; escape, that the water may follow ; we then make use of the handle, and the exterior pressure of the atmo- sphere will raise the water to the height of 30 feet, as in the common atmospheric pump, the valve F will | . then be closed, and 10 feet of the water in the wide cylinder, retained 20 feet above that in the well; then by opening the aperture B, we allow the atmospheric pressure to enter, at the same time pressing the valve E against the aperture D, making it air- tight, and keeping it in that position, we are enabled, by the continued action of the piston, to raise that ten feet of water another thirty feet from its surface in the large cylinder, which will make fifty feet from its surface in the well. Again, by closing the aperture B, we repeat the operation in the same manner as before described. But if we were to have the nar- row cylinder fixed at five feet down the wide one, we should # t - ; * *** ; C ||### : | 30 &'? ſº # |D ſ then be enabled to raise the water fifty-five feet from its surface in the well. We are then enabled to raise water from wells between 50 and 60 feet in depth, not by a multiplication of pumps and cisterns, but by employing the atmospheric pres- sure double, or at two paits of the same pump. Instead of having the wide cylinder A to reach below the surface of the water in the well, it will be only requisite to have it as far down as the part where the valve F is situated. And it will be better to employ a small suction pipe from beneath the valve F, to the water in the well, which will produce the same effect more perfectly, and in a much shorter space of time. . . The Triple PUMP, a sketch of which is given in the following engraving, is taken from Bockler's Theatrum Machinarum. The nature of the machinery by which this pump is worked, will be sufficiently obvious to Åny person after an inspection of the figure. The horizontal wheel C, and its shaft A, are turned by the capstan bars B; this-wheel drives the pinion D, on the axle of which is the equalizing fly E, and the crank F: the rotatory motion of the crank alternately raises and depresses the bar G, with the lever H turning on a roller and pivots, and thus works the pump I: at the same time the connecting rods K move in like manner the lever M, and work the pump O'; and the rods K move the lever N, and work the pump P. If the levers H, M, N, are not so contrived that the extremities of each shall move through equal spaces, the bores of I, O, and P, must be made in the inverse ratio of those spaces, otherwise one or other of the reservoirs may be drawn dry ; a defect that should be carefully guarded against. g Our attention may now be directed to some of the different forms which may be given to the pistons and valves of a pump. The great desideratum in a piston is, that while it be as tight as possible, it should have as little friction as is consistent with this indispensable quality. The common form, when carefully executed, possesses these properties in an eminent degree. This piston is a sort of truncated cone, generally made of wood not apt to split, such as elm or beech. The small end of it is cut off at the sides, so as to form a sort of arch, by which it is The two ends of the conical 0 H * * - 854 P U. M. part may be hooped with brass. This cone has its larger end 1.--- working barrel of the pump Q N. This ... flanch has a groove round it. plate with a grooved edge similar to surrounded with a ring or band of strong leather fastened with nails, or by a copper hoop, which is driven on it at the smaller end; the further this end ºrcaches beyond the base of the cone, the better; and the whole must be of uniform thickness all | round, so as to-suffer equal compression between the cone and | working barrel. The seam or joint of the two ends of this band | a.o.o.º.o.o.º. must be made very close; but not sewed or stitched together, as that would occasion bumps or inequalities, which would spoi its tightness; and no harm can result from the want of it, because the two edges will be squeezed close together by the compression in the barrel. Nor is it by any means necessary that this conſpression be great : this is a very detrimental error of the pump-makers. It occasions enormous friction, and destroys the very purpose which they have in view, viz. render- ing the piston air-tight; for it causes the leather to wear through very soon at the edge of the come, and it also wears the working barrel. % Belidor, an author of the first reputation, has given the description of a piston which he highly extols, and is undoubt- edly a very good one, constructed from principle, and extremely well composed. It consists of a hollow cylinder of metal (fig. 1.) pierced with a number of holes, EE, * - FF, having at top a flanch, whose dia- Fig. 1. meter is nearly equal to that of the { | IEI There is another flanch below, by which this hollow cylinder is fastened with bolts to the lower end of the piston, repre- sented in fig. 2. This consists of a A B, and an intermediate plate which forms the seat of the valve. The con- position of this part is better under- stood by inspecting the figure than by any description. The piston-rod H N is fixed to the upper plate by bolts Fº through its different branches at G O. This metal body is then covered with a cylindrical bag of leather, fastened on DictionARY of MECHANICAL science. applied to the barrel. through the hole of the cross-bars A. B. P U M , . Fig. 2. it by cords bound round it, filling up - . . . . the grooves in the upper and lower. B}– —A plates. The operation of the piston is . as follows:—A little water is poured • e_e into the pump, which gets past the .*.* ." ©, sides of the piston, and lodges below • { in the fixed valve. The piston being s] 0 e º 6 - tº gº iº a e o ' pushed down, dips into this water, and e o e e it gets into it by the valve. But as the | C Go Gº piston in descending compresses the air below it, this compressed air also gets into the inside of the piston, | swells out the bag which surrounds it, and compresses it to the | sides of the working-barrel. | again, it must remain tight, because the valve will shut and keep in the air in its most compressed state ; therefore the When the piston is drawn up piston must perform well during the suction. It must act equally well when pushed down again, and act as a forcer; | for, however great the resistance may be, it will affect the air within the piston to the same degree, and keep the leather close The following piston is also ingenious, and has a good deal — of merii. O P PO, in the figure, is the box of the piston, having a per- foration Q, covered above with a flat valve K, which rests in a metal plate that forms the top of the box. A B C BA is a stirrup of iron to which the box is fixed by screws a, a, a, a, whose heads are sunk in the wood. This stirrup is perforated at C, to receive the end of the piston-rod, and a nut H is screwed on below to keep it fast. DE FED is another stirrup, whose lower part at D D forms a hoop like the sole of a stirrup, which embraces a small part of the top of the wooden box. . The lower end of the piston-rod is screwed; and before it is put into the holes of the two stirrups (through which holes it slides freely) a broad nut G is & screwed on it. It is then put into the holes, and the nut H firmly screwed up. The packing R. R. is then wound about the piston as tight as possible till it com- pletely fills the working-barrel" of the pump. When long use has rendered it in any degree loose, it may be tightened again by screwing down the nut G. This causes the ring DD to compress the packing between it and the projecting shoulder of the box at PP; and thus causes it to swell out, and apply itself closely to the barrel. Prony, in his Architecture Hydrau- Iique, ascribes this invention to M. Bettancourt. We shall add only another form of a perforated piston; which being on a principle different from all the preceding, will suggest many others; each of which will have its peculiar - advantages. O O, in the figure, represents the box of this piston, fitted to the working- barrel in any of the preceding ways as may be thought best. A B is a cross-bar of four arms, which is fixed to the top of the box. C F is the piston-rod going through a hole in the middle of A B, and reaching a little way beyond the bottom of the box. . It has a shoulder D, which prevents its going too far through. On the lower end there is a thick metal plate, turned conical on its upper side, so as to fit a conical seat PP in the bottom of the piston-box. When the piston-rod is pushed down, the friction on the barrel prevents the box from imme- diately yielding. The rod therefore slips The plate E, therefore, When the shoulder D presses * detaches itself from the box. | on the bar A B, the box must yield, and be pushed down the barrels, and the water gets up through the perforation. When the piston-rod is drawn up again, the box does not move till the plate E lodges in the seat PP, and thus shuts the water- y . º - - Ø-...--~~ | "Tº T º - M | | | |||||IIT W | º - W _ % % Ø - - - % - N s G- º º - ſº % n = ==== = . ºn | | - ". a L. | - *T. = −. =#| ||= | | | | || * - w - N º Aº ‘ſ | º º º - º - ſ | | - III. nºminimumumumumumumumumummi T. º - Published by Eisler sºlº cº carton London 1825. _ F U M P U M DICTIONARY OF MECHANICAL SCIENCE. 855 way; and then the piston lifts the water which is above it, and acts as the piston of a sucking-pump. This is a very sim- ple and effective construction, and makes a very tight valve. It has been much recommended by engineers of the first repu- tation, and is frequently used; and, from its simplicity, and the great solidity of which it is capable, it seems very fit for great works. But it is evident that the water-way is limited to less than one-half of the area of the working-barrel. Förif, the perforation of the piston be one-half of the area;the diamé- ter of the plate or ball E F must be greater; and therefore less than half the area will be left for the passage ºf the water by its. sides. * š ...' . . We come now to consider gº given to the valves of an hydraulic engine. ..The valve are, that it shall be tight, of sufficient, streñgth the great pressures to which it is exposed, that it as: sufficient passage for the water, and that it do not allow much to go back while it is shutting. Some engineers make their great valves of a pyramidal form, consisting of four clacks, whose hinges are in the "circumference of the water-way, and which meet with their points in the middle, and are supported by four ribs which rise up from the sides, and unite in the mid- Adle. This is an excellent form, affording the mºst-spacious water-way, and shutting very readily. It seems tdºbe the best possible for a piston. The rod of the piston is bianched out on four sides, and the branches go through the pistă -box, and are fastened below with screws. These branchesºform the support for the four clacks. We have seen a valve of this form in a pump of six feet diameter, which discharged twenty hogsheads of water every stroke, and made twelve strokes in a minute, raising the water above twenty-two feet. There is another form of valve, called the button or tail valve. It consists of a plate of metal A B (see the figure) turned coni- cal, so as exactly to fit the conical cavity b b of its box. A tail C D projects from the under side, which passes through a cross-bar E F in the bottom of the box, and has a little knob at the end, to hin- der the valve from rising too high. This valve, when nicely made, is unexception- able. It has great strength, and is there- fore proper for all severe strains, and it may be made perfectly tight by grinding. Accordingly it is used in all cases where this is of indispensable consequence. It * * is most durable, and the only kind that will do for passages where steam or hot water is to go through. Its only imper- fection is a small water-way; which, from what has been said, cannot exceed, nor indeed equal, one-half of the area of the pipe. If we endeavour to enlarge the water-way, by giving the cone very little taper, the valve frequently sticks so fast in the seat that no force can detach them. And this sometimes hap- §: during the working of the machine; and the jolts and lows given to the machine in taking it to pieces, in order to discover what has been the reason that it has discharged no water, frequently detaches the valve, and we find it quite loose, and cannot tell what has deranged, the pump. When this is guarded against, and the diminution of the water-way is not of Very great consequence, this is the best form of a valve. Analogous to this is the simplest of all valves. It is nothing more than a sphere of metal, to which is fitted a seat with a small portion of a spherical cavity. Nothing can be more effectual than this valve : it always falls into its proper place, and in every position fits it exactly. Its only imperfection is the great diminution of the water-way. If the diameter of the Sphere do not considerably exceed that of the hole, the touch- ing parts have very little taper, and it is very apt to stick fast. It opposes much less resistance to the passage of the water than the flat under-surface of the buttºn valve. The spherical valve must not be made too light, otherwise it will be hurried up by the water, and much may go back while it is returning to its place. Description of an Improved PUMP for Draining, constructed by Henry W. Revely, Esq. Civil Engineer, 33, King-street, West, Bryanstone-square, London.—The principal objects in the con- struction of this pump, are the following: “To obtain a º: briefly the foråſ & * * ** * machine of Harge dimensions, and of easy transportance; to afford sufficient scope for the most advantageous application of the united strength of many‘men, in raising large bodies of water to moderate heights, as required in drainingiarge tracts of land, sinkiſºfºundations, &c. &c. To prevent, as far as possiblétié choking, and final destruction, of the principal parts of the machine, by the impurities with which water, under such circumstances, is always loaded.” * *. Explanation ºf the Drawing. (See Plate Pump for Draining.)— Fig. 1. Front elevation of the whole machine. a, a, the frame- work usually constructed of wood. c, c, the levers and hand- rails, by which the pumps are worked, as in the common fire- j.6ngine, m, m, two stages, or platforms, on which the men a -l stand.” th sh; h, the suction pipe, which branches out into two, at the uppeºpart, in order to supply both the cylinders. This # # pipe is divided into short lengths by screw-joints, to suit vari- ous depths. d, d, the double rising-pipe, which communicates with the large cistern, or general receiver. a., a, the cistern, or general receiver, to which theisiäg-pipe; and pump cylin, ders, are firmly united, f, the delivering spout, - * N. B. The same letters refer to the same parts in all the figures: # Fig. 3; Asside section, shewing the internal construction of the whole, o, the suction valve. p, the rising valve, r, a smallgä6pper spring placed behind the rising-valve, in order to ensº its closing rapidly. *Observation.—The valves and their seats are of an oblong rectangular form, and are made entirely of metal, without any fitting whatsoever, so that they can never be gut of order. Fig. 3. A back view, with a section of one of the cylinders. s, t, the pump-arms, with their pistons attached in the com- mon way. * Fig. 4. A side view. n, n, the spindle, to which the working levers and 'pump-arms are:-attached. e, one of the cylinders, or pump-barrels, which rise a few inches above the bottom of ...the cistern, to a sufficient height to prevent the dirt and stones, aceumulated in the latter, from falling in, but not so high as to | hinder the clear water from flowing: into them, and keeping their pistons free and air-tight. g, ‘....". -through which, when necessary, the valves may be cleaned and examined, q, a plug, used for the double purpose of discharging the pump of its water, and cleaning the belly-part, from time to time, of the sand and gravel which are deposited there'during the working. Fig. 5. Is a plan of the whole machine, with its levers and hand-rails ready for work. g General Observations.—It is evident from this construction, that the water which is pumped up does not pass through the cylinders ; it cannot, therefore, although loaded with sand and gravel, injure them in any sensible degree. The pistons, how- ever, are constantly working between two waters, and remain perfectly free and air-tight. The machine, represented by this drawing, has the barrels of its pumps of the internal diameter of fourteen inches, and the length of each arm of its levers, eight feet. By placing six men outside, and four men within each hand-rail, the united strength of twenty men, acting at the extremity of a long lever, may be applied to working this pump ; but in ordinary cases, where such an exertion is not requisite, half that number will be sufficient. The quantity of water raised by this pump, will vary according to the depth from which it is to be raised, and the power applied. It may be considered, however, in general, to raise from 2000 to 3000 cubic feet per hour. Description of a new and efficient Hydropneumatic PUMP for the Compression of Gasses.—Lamps for condensed gas, are found so convenient and manageable in every respect, and oil-gas applied to the purpose of illumination is so preferable on various accounts to that made from pit-coal, that they are daily coming more and more into use. Independently of their adoption by private families, they are now employed in many shops, where the goods are of a nature to be injured by sulphurized hydrogen (always present in coal-gas,) and their use is extending among public institutions and large establishments about Town. New- gate has, for some months, been regularly lighted by means of portable gas lamps. * The establishment of the Portable Gas Companies was at first viewed in a dubious light, but time and experience have so 856 P U M Tº U M DICTIONARY OF MECHANICAL SCIENCE, far removed suspicion, that they now receive ample patronage. To render their establishment complete, there was nothing wanted, with the lamp, but such, a condensing pump as we are now about to lay before our readers. ..º.º.º. In consequence of the general use, to whigºś, be brought when highly compressed, it becóñº §ºr *_º . ſº §§ ascertain the best method of reducing it to that state, sº that shall be most useful and advantageous to the public. The pre- sent method ºf compressing gas is atténded with a great many disadvantages; these principally consist of a considerable loss of gas during the operation of compression, an immense loss of power in consequence ºf the gas not being completely forged out of the pump barrel; and the excessive wear and tear of the machinery employed therein. The pump which has hitherto been used for this purpose con- sists of a barrel well bored out, open at one end, as A, fig. 1. see plate Hydro-Pneumatic Pump, and Bute's Furnace,) with the two valves c and d at the other end; and the solid piston B'work- ing therein. This is, perhaps, the best possible arrangement of the piston pump, and is the one adopted by some of the first engineers and machinists. < * Now, in the use of this pump it is impossible that the piston can be worked so close as to strike the bottom; there must be some space for clearance, otherwise there would be great dan- ; ger of damaging the valves, Or doiggºther mischief.; Say; ina. pump of 12-inch strokéând 5 inchesºdiameter, the spages, li wº ed between the bottom of the piston and the bottom of jº, §: shall be one-eighth of an inch, which is no great deal; now as the operation of compression goes on, this space will be gra- dually increased, and when the gas arrives at a pressure of 30: atmospheres, or 550 lbs. upon the square inch, (which is the average, pressure emplºyed by the Portable Gas Company there will then be the efit the bottom of the barrel and the piston, which will maturally cause them to recede the one from the other; and from the ac- tual spring of the cranks, the looseness and wear of bearings, spring of the connecting rods and crossheads, and even of the bettom of the pump itself, we may fairly conclude that under this great pressure the piston does not come within 4 of an inch of the bottom ; consequently there remains that quantity of gas under the great pressure of 30 atmospheres, which cannot be forced out, and which, as the piston recedes for the return stroke, will expand in the barrel, and occupy a great part of the space ; thereby preventing the admission of another full charge And this is one of the greatest defects of this sort of pump ; for allowing the space to be one quarter of an inch, it will be just one forty-eighth of the whole capacity of the pump ; and adding to this the space left by the rising of the eduction valve d, which will remain open until the piston has receded a little in the return stroke, we may doubtless presume that a portion of compressed gas, equal in volume to one-fortieth of the whole stroke of the pump, remains behind every time in the barrel; therefore when the pump commences working, and the gas in the receiver arrives at a pressure of 10 atmospheres only, three fourths of the gas is forced out of the barrel,-at 20 atmo- spheres, one half-at 30 atmospheres, one quarter;-and when it arrives at 40 atmospheres, the pump will cease to act, as the compressed gas which remains will expand itself, and fill the whole barrel; and therefore no more gas can then be admitted from the gasometer. Moreover, there is an actual loss of gas occasioned by the leaking of the piston, which is a failing that these pumps are more or less liable to ; for, whether they be packed with metallic rings, cupped leathers, or hemp packing, still there will be some escape under this great pressure ; and if the leathers, &c. are screwed up so hard as totally to prevent the escape of the gas, the friction will become immense, conse- queñtly one half of the power will be absorbed, and thus very little advantage would be gained by the remedy. These observations will, it is presumed, place the defective operation of the common forcing pump in a clear point of view, and will naturally lead us to comprehend the advantages of the bydro-pueumatic pump. It will have been observed, that the great evil in the common pump is the space or cavity that is left when the piston is down at the bottom of the stroke. Now the remedying of such evil is the primary object sought for in i). 㺠.rº %fiółmous weight of 9000 lbs. acting againstºl fluid is introduced into the chamber of the pump, which, filling up the whole of the cavity when the pistonisłdºn, necessarily forces out every particle of the compressed gas; the method of gh will be eadily understöödin the descrip- ºš. ºścº ** Yºº ... º.º.º. . . . . . . . . #3 *** ***** sº 2.3. ățiań of the hydro-pneuma- guiñp. ºis-à frºm ºf supporting the machine; the “puriffºonsists ºf two chambers Band D : in the chamber B works the solid plinger C, through a cupped, leather w; by means of the crank n, and the slings m m. .D is the pneumatic-chamber, at the top of which are placed the induction valvee and the eduction Yalygº; over the latter is placed a small vessely with * * * * the piñé h leåging tº the receiver, ºr, Nºwhen the plinger Q is at the bottom of the stroke as Wnegº ...tº shewijn º;; chamber D is then to be quite fullèfºil, or 'some other non-elastic ſluid : and for further secu- rity, a small quantity of oil is also to be above the eduction valve c ; when the plunger C is drawn back the oil in the cham- ber D will sink to the level of r s, and the space will then be filled with the gas, which will rush from the gasometer through the pipe f and valve e ; but when the plunger is again forced down, the oil will rise to the same height as before, again ſilling up the whole capacity of the chamber D, and forcing out every particle of gas through the valve c ; and so on alternately: If, through the increased pressure, or from some other cause, the oil in the chamber D-should not be quite sufficient to fill up the whole cavity on the return of the plunger, it is of no conse- quence, because the moment the valve c rises ever so little, the oil which was above the valve will descend, and displace the gas in the chamber D. The vessel g is a small reservoir for the oil, and to receive any drainage from the gas; the tube k is for ascertaining that the proper quantity of oil is in the apparatus, or for supplying more when required. It is possible that a trifling leak may take place through the valve c; but this will be of little consequence, as the escape of a small quantity of a non-elastic ſluid back into the chamber D is not attended with the twentieth part of the inconvenience to which the escape of the same volume of compressed gas would be subject. Now, the particular ad- vantage of this pump is, that the full charge of gas is forced through the valve c at every stroke of the piston, whether the pressure be equal to 1, 10, or 50 atmospheres. Indeed, there are no limits to the degree of compression of which this pump is capable; provided the parts of the machine be sufficiently Strong to withstand the strain, and an adequate power be employed; while it is supposed that the operation of the com- mon pump is not capable of extending beyond a pressure of 3 or 40 atmospheres. - A diagram may be constructed, which will furnish an easy method of ascertaining the power required to work the above pump sufficiently near for all practical purposes. Thus let a straight line A B be divided into 32 equal parts, of which make G B = 16; F G = 8; E F = 4; DE = 2; C D = 1 ; and A C = 1. Then if we consider this whole line equal to the space which the plunger moves over in one stroke of the pump, it is plain that at B, the commencement of the stroke, the stroke will be equal to one atmosphere only, represented by a vertical line B b : but when the plunger has reached G, it will have made half a stroke, and the stroke will then be equal to two atmospheres, as shewn by a line G g = 2× B b. Again, when the plunger is at F, it will have made three-quarters of the stroke, and the force will then be equal to four atmospheres = Ff-4B b; and so on until the plunger arrives at C, when it will have made 34 part of the stroke, and the compression and force will then be equal to 32 atmospheres, equal to a line C c = 32 × B b. Therefore, if we consider bg, g fife, &c. as so many straight lines, then will the areas G b, F g, Ef, D e, &c. be nearly as the momenta of the plunger passing over the several spaces B G, C, F, F E, &c. But the several areas G b, Fg, Ef, .&c. are all equal to each other; there- fore the whole of the momenta of the plunger passing through the space B C, will be equal to five times the area G 9 b B; that g G + B b x G B 2 To this must now be added the momenta of the plunger pass- is, equal to 5 × = 5 × 1; x 16 = 120. this improvement; for this purpose a quantity of non-elastic ing from C to A, the last #d part of the stroke, which will be |-|- |- |×，//////, ,/////////^'^ : ·„ae//|-//^： /º/，|×// √） ！ 7% | 17 |-» | , ، ، ، ، |-// ± //， // '^^^ſº/，^/. |-×|- /º/， ſae 2. |-/…/， |×， |- ſº} . - | - * 1. Zſºſ， A . A· %%. |7. ……….… |- - - - - - ----- - - - -- - - -|- P U M P U M 857 DICTIONARY OF MECHANICAL SCIENCE. as 32 × 1 = 32;" which added to the above gives 152. We have now to deduct the pressure of one atmosphere, which has as- sisted the plunger in passing over the space B A ; that is 32 x 1 =32, which taken from the foregoing quantity will leave 120 for the whole absolute momenta of the plunger. Now, divide this quantity by the number of parts in the line A B (= 32,) and it will give 33 atmospheres, or 564 lbs. per square inch for the average force on the plunger during the whole stroke, when compressing gas equal to 32 atmospheres. Therefore as the pump acts but singly, if a fly-wheel of sufficient weight be em- ployed, a power equal to about 30 lbs. on every square inch of the plunger will be nearly adequate to the working of the pump. If gas of the pressure of only 20, or any other number of atmospheres less than 32, be required, the necessary average power for producing it can readily be ascertained from the same diagram ; for let the line A m represent the proposed pressure, then cutting off the upper part of the figure by the line m n, parallel to the base A B ; and calculating the remain- ing area in the manner already described, it will give the required power. And if the pressure should be required to be more than 32 atmospheres, then by increasing the height of the diagram towards a c in the manner already shewn, we can also in that case estimate nearly the necessary required power. * Head-PUMP, a moveable pump, to put over the bows or side of a ship. These were formerly used in the navy, to pump water into the ship for washing the decks, &c. but since the invention of a cistern in the well, they are quite disused. Pump-brake, the wooden lever or handle by which a hand- pump is worked, Pump-bolts, two pieces of iron, with a knob at one end, and a hole for a pin or forelock in the other; one serves to fasten the pump-spear to the brake, and the other as a fulcrum for the brake to work upon. Pump-dales, long wooden tubes, extending from the chain-pumps across the ship, and through the, side, serving to discharge the water without wetting the decks. Pump-gear, any materials requi- site for fitting or repairing the pumps, as boxes, leather, &c. Jump-spear, that bar of iron, which, communicating with the upper box, is also attached to the end of the brake whereby the former is put in motion. The Pump sucks, is said of the pump when the water is drawn out, and there comes up nothing but froth and wind. - PUMP Chain, consists of a long chain equipped with a suffi- cient number of valves a proper distances, which working upon two wheels, one above and the other below, passes downward through a wooden tube, and returns upward through another. it is managed by a long winch or roller, whereon several men may be employed at once, and thus it discharges in a limited time a much greater quantity of water than the common pump, and with less fatigue and inconvenience to the labourers. PUMP Irons of the following description have been made by some engineers, and they have answered very well when pro- perly constructed. They are described in the 62d No. of the Mechanic's Magazine, thus:–Fig. 1 is the plan generally adopt- ed for a common lifting pump. A is the pump standard, with the handle B connected to it; C the pump rod; D a sling, with a double joint at each end; the upper part of the pump rod C passes through a guide above the joint G, which always keeps the pump rod upright; the joints should be bushed with steel, and steel pins turned and fitted nicely, and they will last for many years without shaking in the least. But when I am con- fined for room, as is frequently the case, I use fig. 3, where A is the joint of the pump lever or handle; B a radius rod of the same length from B to E, as the pump lever from A to D ; the ends D and E are connected by a link with three holes in it; the pump rod is slung to the middle hole, and by the radius rod and pump lever being fixed in the same vertical plane, the hole C will describe a straight line, or very nearly so, provided the arc FG does not much exceed 40 degrees. Fig.2 is for deep wells, where the pump is obliged to be fixed in the well. The pump rod E is attached to a beam or lever C, which swings on a centre D; the connecting rod B is also jointed to the beam C at the extremity, the other end being fixed to the crank pin in *Because, when the gas in the chamber is compressed equal to 32 atmo- spheres, it will then raise the valve, and make it escape into the receiver, as we suppose the pressure not to exceed32 atmospheres. 88. the flange A, which has holes, marked to FFF, at different distances from the centre, in order that the quantity of water to be raised may be regulated by giving the pump rod E a longer or shorter stroke. The flange A is firmly fixed on a shaft with a fly-wheel at the other end, and a handle fixed to turn with the weight marked W at the outer end of the beam; C has a set screw at the top side, to allow it to be removed further off, *- A. Fºoze View ~ | | S &l ... ." ~~ * • * or brought nearer to, the centre, as may be required. It should be placed so as to balance the weight of the pump rod, and half the column of water to be lifted. The inventor of this, fixed one pump, by which with the assistance of a wheel and pinion, one man with ease raised 7 gallons of water per minute from the depth of 120 feet. Improvement in Pump Irons.—An improvement in the con- struction of pump irons, was invented by Mr. J Bennett, of Lin- coln, about twelve months ago, and was so much approved as to be immediately adopted º by the other plumbers in that city and its neighbour- hood; and as it may be beneficial to others, we allow it a place in our Dic- tionary. Description.—AA repre- sent the front edges of the pump sides or standards; B, a cast iron friction wheel, 5% inches diameter, for the purpose of keeping the bucket-rod C in a per- pendicular direction; it works in two grooves made for that purpose, in two pieces of hard wood D D, which are fastened to the sides of the standards; (fig, 2 represents a section of those pieces); E the han- | dle, which may either be of | wood or iron ; F connects the handle to the centre of the wheel by two steel bolts; G, a cast iron chair, in which is fastened a brass bush; two of these chairs are let into the side of the working standard, one on each side of the handle, and made fast by screw bolts and nuts. The handle has a fast axle, which works in the brass bushes, and which should be turned, and made to fit very exact, as should also the steel bolts. The mo-' tion will then be very steady, and the pump will last for years without getting out of repair. -- 10 I P U R. P U Z DICTIONARY OF MECHANICAL SCIENCE. Before quitting the article pump, we will describe the Centri- fugal Check Hooks, invented by Mr. E. Spear, which formed part of an apparātus for the prevention of accidents in raising men or minerals out of mines, by means of a rope and bucket. The idea of centrifugal check-hooks appearing to be new, and JFre. 2. & R d. r— ~ $ &: - applicable in other machines, for the purpose of stopping them when put into inordinate motion, or running wild, as the phrase is, the Society of Arts, &c. rewarded the inventor with their silver Vulcan medal, and directed that it should be inserted in their Transactions. Fig. 1 is a front view, and fig. 2 is a side view, of the appa- ratus; a a, a bar fixed on the end of the axis d, fig. 2; b b, two hooks swinging freely on the ends of the same bar; c, a short bar projecting from the frame of the machine for the hooks to catch hold of. When the bar a a revolves moderately, the hooks b b hang down by their own gravify, and keep clear of the bar c, but when it revolves too quick, the centrifugal force causes them to diverge, as shewn by the dotted lines, and one of them catches hold of the check bar c, and stops the revolu- tion of the axis entirely. PUNCHEON, a little block or piece of steel, on one end whereof is some figure, letter, or mark engraved either in creux or relievo, impressions of which are taken on metal or some other matter by striking it with a hammer on the end not en- graved. There are various kinds of these puncheons used in the mechanical arts ; such for instance are those of goldsmiths, cutlers, pewterers, &c. PUNCTUATION, the art of dividing a written composition into sentences, or parts of sentences, by points or stops, for the purpose of marking the different pauses which the sense requires. PUNICA, the Pomegranate Tree, a genus of the monogynia order, in the icosandria class of plants, and in the natural method ranking under the 39th order pomaceae. The calyx is quinquefid, superior; there are five petals ; the fruit is a multi- locular and polyspermous apple.—The fruit of the pomegranate is about the size of an orange, and has the general qualities of the other sweet summer fruits, allaying heat: “[uenching thirst, and gently loosening the belly. The rind is a strong astringent, and as such is occasionally made use of. PUNT, a sort of flat-bottomed boat, whose floor resembles the platform of a floating stage. They are used in caulking, breaming, or repairing the bottom of a ship, and in shallow rivers. - PURCHASE, in Law, the buying or acquiring of lands, &c. with money, by deed or agreement, and not by descent or right of inheritance. A joint purchase is when two or more persons join together in the purchase. PURCHAse, a name given to any sort of mechanical power employed in raising or removing heavy bodies, or in fixing or extending the ship’s rigging ; such are the tackles, windlasses, winches, capstans, screws, and handspikes. - PURITAN, a name formerly given in derision to the dissen- ters from the church of England, on account of their professing to follow the pure word of God in opposition to all traditions and pure constitutions. - PURLINS, in Building, those pieces of timber that lie across the rafters on the inside, to keep them from sinking in the mid- dle of their length. * * - PURPLE, a colour composed of a mixture of red and blue. PURSER, an officer appointed by the lords of the admi- ralty to take charge of the provisions of a ship of war, and to see that they are carefully distributed to the officers and according to the general printed naval instructions. ... PURSUIT, CURVe of, is one generated by the motion of a point, which is always directed towards another point also in motion along a right line, the velocity of the two points bearing any determinate ratio to each other. Thus let A and B be two bodies, the one A moving along the line A C, with any given velocity v ; and the other B, moving with a Velocity V, and in such a manner as to be always 5 directed towards the body A, then is the curve BC thus described by B, the curve of chasee or the curve of pursuit. PUS. The liquid called pus is secreted from the surface of an inflamed part, and usually moderates and terminates the inflammation. 4 PUTLOGS, or Putlocks, in Building, are short pieces of timber about seven feet long, used in building scaffolds. They lie at right angles to the wall, with one of their ends resting upon it, and the other upon the poles which lie parallel to the side of the wall of the building. - - PUTREFACTION. The decomposition of animal and vege- table matter, accompanied with a foetid smell. The solid and fluid parts are changed in gaseous matter and vapours, and earthly particles remain. If animal or vegetable substances be congealed by hard frost, or made very dry and hard, so that no motion of their particles can take place, putrefaction is stop- ped. - - PUTTY, in the Arts. When tin is melted in an open vessel, its surface soon becomes covered with a gray powder, which is an oxide of the metal. If the heat is continued, the colour of the powder graduakly changes, and at last becomes yellow. In this state it is known by the name of putty, and employed in polishing glass and other hard substances. PUTTY, is also a kind of paste compounded of whiting and linseed oil, beaten together to the consistence of a thick dough. - - PUY DE DOMME, ExPERIMENT OF, a term under which crew, A. D AZ | the celebrated experiment of Pascal is commonly spoken of, and by which the gravity of the atmosphere was demonstrated beyond every possible objection. It was some time after Torri- celli had first asserted the pressure of the atmosphere, before philosophers could divest themselves of their prejudices on this head; and various hypotheses were accordingly advanced to account for the suspension of the mercury in the tube, as stated in the Torricellian experiment. Even Pascal had his doubts on the subject. At length, however, he suggested that if the pressure of the atmosphere was the real cause of that suspension, the mercury ought to sink very sensibly on ascend- ing a high mountain, and the Puy de Domme was selected for this purpose. On making the experiment, the result realized his expectation; the mercury having gradually sunk in the ascent where it was extremely obvious; and rose again, upon descending, to the same height as at first. No doubt could then any longer remain as to the real cause of the suspension, and it was accordingly universally admitted by every philoso- pher in Europe, and the name of the mountain was from that time transferred to the experiment, which is now usually called the Experiment of the Puy de Domme. PUZZOBANA, or Pozzul ANA, a kind of earth found about Puteoli, Baiae, and Cumae, in the kingdom of Naples. It is thrown out from the burning mouths of volcanoes, in the form of ashes; sometimes in such large quantities, and with so great violence, that whole provinces have been covered with it to a considerable distance. Puzzoiana is of a gray, brown, or blackish colour; of a loose, granular, or dusty and rough, po- rous or spongy texture, resembling a clay hardened by fire, and then reduced to a gross powder. It has various heterogeneous substances mixed with it. Its specific gravity is from 25 to 2:8; and it is, in some degree, magnetic ; it scarcely effervesces with acids, though partially soluble in them. It easily melts per se; but its most distinguishing property is, that it hardens very suddenly when mixed with one-third of its weight of lime and water, and forms a cement which is more durable in water than P Y R P Y R. S59 DICTIONARY OF MECHANICAL SCIENCE. any other. According to Bergman's analysis, 100 parts of it contain from 55 to 60 of siliceous earth, 20 of argillaceous, 5 to 6 of calcareous, and from 15 to 50 of iron. Its effects, however, in cement may, perhaps, depend only upon the iron, which has been reduced into a particular substance by means of subter- raneous fires; evident signs of which are observable in the places where it is obtained. - PYRAMID, in Geometry, is a solid having any plane figure for its base, and triangles for its sides, all terminating in one common point or vertex. If the base of the pyramid is a regular figure, the solid is called a regular pyramid, which then takes particular names according to the number of its sides, as triangular, square, pentagonal, &c. the same as the prism. See PRISM. If the perpendicular demitted from its vertex falls on the centre of the base, the solid is called a right pyramid, but if not it is oblique. The principal properties of the pyramid may be stated as follows:–1. Every pyramid is one-third of a prism of equal base and altitude. 2. Pyramids of equal bases and altitudes are equal to each other, whether the figure of their bases be similar or dissimilar. 3. Any section of a pyra- mid parallel to its base will be similar to the base, and these areas will be to each other as the squares of their distances from the vertex. 4. Pyramids, when their bases are equal, are to each other as their altitudes, and when their altitudes are equal they are to each other as their bases; and when nei- ther are equal, they are to each other in the compound ratio of their bases and altitudes. - To find the Solidity of a Pyramid.—Multiply the area of the base by its perpendicular altitude, and one-third of the pro- duct will be the solidity. To find the Surface of a Pyramid.-Multiply the perimeter of the base by the slant altitude of one of its faces, and half the product will be the surface. Or, find the area of one of its tri- angular faces, and multiply by the number of them, which is the same thing. , - Frustrum of a Pyramid—Is the solid formed by cutting off the upper part of a pyramid by a section parallel to its base. To find the Solidity and Surface of a Frustrum of a Pyramid.— Let A represent the area of the greater end, a that of the less, and h its height or altitude ; also let S and s represent the cor- responding sides of the two ends, and p the tabular number, answering to the particular figure of the base; then, 1. Solidity = (A + VA a + a) × h 2. Solidity = (S” + Ss -- s?) × ph 3. Surface - (S -- s) x n b where n is the number of sides, and b the slant height of the frustrum. The pyramids of Egypt have been considered from time im- memorial, among the most stupenduous wonders of the world; and no one can doubt that in strength and elevation they are superior to any other monuments that art can boast. Of these venorable buildings the most remarkable are the three pyramids of Memphis. The dimensions of the largest of them have been variously estimated. According to Greaves, its perpendicular elevation is 499 feet, and its oblique height 625 feet, which latter is the measure of its base. Its four faces look towards the four cardinal points of the compass: each face has a base of 110 fathoms, and each face forms an equilateral triangle. It results from these dimensions, and from the latitude under which this pyramid is raised, that, fourteen days before the spring equinox, (the precise epoch in which the Persians cele- brated the renewing of nature,) it would cease to throw any shadow at mid-day, and that it would not project any shadow again (at mid-day) until fourteen days after the autumnal equinox ; consequently, the day on which the sun’s southern declination was 5 deg. 15 min. (which happened twice a year— once before the vernal equinox, and once after the autumnal equinox,) the sun would appear at mid-day precisely upon the very pinnacle of the pyramid. His majestic disk, placed upon that immense pedestal, would seem to repose upon it for some minutes, whilst his adorers, kneeling down at its foot, prolong- ing their view along the inclined plane of the northern face of the pyramid, contemplated the great Osiris, either as he de- scended into the shade of the tomb, or as he rose triumphant out of it. . It would appear that the Egyptians, ever great in all their designs, had executed a project, the most daring, which imagination could conceive, that of placing a pedestal for the sun and for the moon, or for Osiris and Isis, at mid-day for the one, and at midnight for the other, when they arrived in that part of the heavens near which the line passes that separates the northern from the southern hemisphere, the reign of good from the reign of evil, the empire of light from the empire of darkness.—This pyramid covers upwards of eleven English acres, and may be asgended on the outside by about 208 steps. The symmetry of the work is equal to its durability, and in all probability these renowned fabrics will continue till the globe itself shall be dissolved. - PYRITES, a genus of inflammable substances, composed of sulphur which has dissolved or saturated itself with metals. PY Rites, a native compound of metal, with sulphur. PYROLIGNEOUS ACID. Pyroligneous acid, or what is generally termed vinegar of wood, is that which promises to be of most use as an animal antiseptic. From its low price it is adapted for general use ; more particularly, as it not only pre- serves the food from putrefaction, but also gives it that smoky and acid taste peculiar to well-dried hams and red herrings. Indeed the only difference in using this acid, and drying by turf or wood smoke, seems to be merely the mode of operation; for in both cases this acid is the agent employed. In one case, the animal substance is acted on during the distillation of the acid; and in the other, the already-formed acid is applied to the substance by immersion.—This acid, the product of the dis- tillation of wood, is now well known in Britain as an article of commerce, and in its native state is a liquid of the colour of white wine, possessing a strong acid and slightly astringent taste, combined with an empyreumatic smell. When allowed to remain in a state of rest for eight or ten days, tar of a black colour subsides, and the acid is then comparatively trasparent. Besides its antiseptic use, this acid is employed instead of acetate of lead by the calico printers, to make their acetate of alumina, or iron liquor. Though not very pure, it answers suf- ficiently well for blacks, browns, drabs, &c.; but for yellows and reds it is not so good, owing to the oil and tartar that is in combination with it. * PYROMALIC ACID, is obtained from the malic or sorbic acid, by distilling in a retort. PYROMETER, a machine contrived to measure the expan- sion of metals and other bodies, occasioned by heat. Muschen- brocck was the original inventor of the pyrometer; the nature and construction of his instrument may be understood from the following account. If we suppose a small bar of metal, 12 or 15 inches in length, made fast at one of its extremities, it is ob- vious that if it be dilated by heat it will become lengthened, and its other extremity will be pushed forwards. If this extremity then be fixed to the end of a lever, the other end of which is furnished with a pinion adapted to a wheel, and if this wheel move a second pinion, the latter a third, and so on, it will be evident that by multiplying wheels and pinions in this manner, the last will have a very sensible motion; so that the moveable extremity of the small bar cannot pass over the hundredth or thousandth part of a line, without a point of the circumference of the last wheel passing over several inches. If this circum- ference then have teeth fitted into a pinion, to which an index is attached, this index will make several revolutions, when the dilatation of the bar amounts only to a quantity altogether insensible. The portions of this revolution may be measured on a dial plate, divided into equal parts; and by means of the ratios which the wheels bear to the pinions, the absolute quan- tity which a certain degree of heat may have expanded, the small bar can be ascertained ; or, conversely, by the dilatation of the small bar, the degree of heat which has been applied to it may be determined. Such is the construction of Muschenbroeck's pyrometer. It is necessary to observe, that a small cup is adapted to the machine, in order to receive the liquid or fused matters, subjected to experiment, and in which the bar to be tried is immersed. When it is required to measure, by this instrument a considerable degree of heat, such as that of boil- ing oil or fused metal, fill the cup with the matter to be tried, and immerse the bar of iron into it. The dilatation of the bar, indicated by the index, will point out the degree of heat it has assumed, and which must necessarily be equal to that of the matter into which it is immersed. This machine evidently serves 860 P Y R. P Y X DICTIONARY OF MECHANICAL SCIENCE. º, to determine the ratio of the dilatation of metals, &c.; for by substituting in the room of the pyrometric bar other metallie bars of the same length, and then exposing them to an equal degree of heat, the ratios of their dilatation will be shewn by the motion of the index. Muschenbroeck has given a table of the expansion of the dif- ferent metals in the same degree of heat. Having prepared cylindrical rods of iron, steel, copper, brass, tin, and lead, he exposed them first to a pyrometer with one flame in the mid- dle ; then with two flames; and successively to one with three, four, and five flames. But previous to this trial, he took care to cool them equally, by exposing them some time upon the same stone, when it began to freeze, and Fahrenheit's thermometer was at thirty-two degrees. The effects of these experiments are digested in the following table where the degrees of expan- sion are marked in parts equal to the Tºkoo part of an inch. It is to be observed of tin, that it will easily melt, when heated by two flames placed together. Lead commonly melts with three flames, placed together, especially if they burn long. From these experiments, so far as they are correct, it appears, at first view, that iron is the least rarefied of any of these metals, whether it be heated by one or more flames ; and therefore is most proper for making machines or instruments which we would have free from any alterations by heat or cold, as the rods of pendulums for clocks, &c. So likewise the measures of yards or feet should, if of metal, be made of iron, that their length may be as nearly as possible the same, summer and winter. - Expansion of ...... Iron. Steel |Copper | Brass. Tin. |Lead By one flame, - 80 S5 | 89 || 110 | 153 |155 By two flames placed * * pººr close together, 117 | 123 || 1 || 5 || 220 274 By two flames 2} inches º distant, 109 || 94 92 141 |219 |263 By three flames placed gº close together, 142 168 193 || 275 By four flames placed gº * close together, 211 270 270 361 By five flames, 230 || 3 || 0 || 310 377 - By the help of this instrument Mr. Ellicot found upon a me- dium, that the expansion of bars of different metals, as nearly of the same dimensions as possible, by the same degree of heat, were as follow. Gold, Silver, Brass, Copper, Iron, Steel, Lead. 73. 103 95 89 60 56 149 The great difference between the expansions of iron and brass has been applied with good success to remedy the irre- gularities in pendulums arising from heat. (Phil. Trans. vol. xlvii. p. 485.) * Mr. Graham used to measure the minute alterations, in length of metal bars, by advancing the point of a micrometer-screw, till it sensibly stopped against the end of the bar to be measured. This screw, being small and very lightly hung, was capable of agreement within the three or four thousandth part of an inch. On this general principle Smeaton contrived his pyrometer, in which the measures are determined by the contact of a piece of metal with the point of a micrometer screw. The late Mr. Ferguson also invented two pyrometers, descrip- tions and figures of which are given in his Lectures. Mr. Wedgwood, the ingenious manufacturer of the finest earthenware from basaltic masses, or terra cotta, has contrived a curious pyrometer: he employs small cubes of dry clay : be- cause that species of earth has the remarkable property of con- tracting in its bulk, when submitted to the fire, and not again expanding on suddenly exposing it to the cold air. In order to ascertain the precise degree of heat in an oven, he puts one of his clay cubes into it, and after having acquired the temperature of the place, he immediately plunges it into cold water. Now, the size of the cube (that was exactly adjusted to half an inch square) is measured between two brass rules, the sides of which are somewhat obliquely disposed, so as to form an inclining groove, into which the cube may be slidden. In proportion as the bulk of the latter has been contracted by heat, it passes down deeper between the scales, on which the various degrees, of temperature have been previously marked. Thus, when the division of the scale commences from the point of red heat vi- sible in day-light, and the whole range is divided into 240 equal parts, it will be found that Swedish copper melts at 28; gold at 32; iron at from 130 to 150 degrees; above this point, the cubes could not be heated. But if one of these clay squares be put into an oven where other materials, such as bread, earth- enware, &c. are to be baked, they may be usefully employed for regulating the necessary degree of heat. Perhaps, however, this gauge does not afford so constant and accurate a measure for the highest degrees of heat, as the dilation of mercury or of alcohol does for the lower. PYROPHORUS. By this name is denoted an artificial pro- duct, which takes fire or becomes ignited on exposure to the air. Hence, in the German language, it has obtained the name of luft-Zunder, or air tinder. It is prepared from alum by cal- cination, with the addition of various inflammable substances. PYROTECHNY, is, properly speaking, the science which teaches the management and application of fire in divers opera- tions; but in a more limited sense, and as it is more commonly used, it refers chiefly to the composition, structure, and use of artificial fire-works. The ingredients are, 1. saltpetre, purified for the purpose : 2. Sulphur, and 3. charcoal. Gunpowder is like- wise used in the composition of fire-works, being first ground, or, as it is technically termed, mealed. Camphor and gum ben- zion are employed as ingredients in odoriferous fire-works. The proportions of the materials differ very much in different fire- works, and the utmost care and precaution are necessary in the working them to a state fit for use, and then in the mixing. In this work we cannot enter on the subject with a sufficient degree of minuteness to teach the method of making of fire- works, and shall therefore content ourselves with the brief notice of the proportions of the materials in some of the more common and more interesting articles in use. The charges for sky-rockets are made of saltpetre, four pounds; brimstone, one pound; and charcoal one pound and a half; or by another di- rection, saltpetre, four pounds; brimstone one pound and a . half; charcoal, twelve ounces; and meal powder, two ounces. These proportions vary again according to the size of the rocket: in rockets of four ounces, mealed-powder, saltpetre, and char- coal, are used in the proportions of 10, 2, and l ; but in very large rockets the proportions are saltpetre, four; mealed pow- der and sulphur one each. When stars are wanted, camphor, alcohol, antimony, and other ingredients, are required according as the stars are to be blue, white, &c. In some cases gold and silver rain is required; then brass-dust, steel-dust, saw-dust, &c. enter into the composition; hence the varieties may be almost indefinite. With respect to colour, sulphur gives a blue, camphor a white or pale colour, saltpetre a clear white yellow, sal-ammoniac a green, antimony a reddish, rosin a copper colour. - PYRUS, the Pear Tree, a genus of the pentagynia order, in the icosandria class of plants, and in the natural method rank- ing under the 36th order, pomaceae. To this genus Linnaeus has joined the apple and quince. There are thirteen species. PY RUS Cydonia. (The Quince.) The seeds abound with a mucilaginous substance, of no particular taste, which they readily impart to watery liquors: an ounce boiled in three pints of water, will render it thick and ropy, like the white of an egg. A syrup and jelly of the fruit, and mucilage of the seeds, used to be kept in the shops. PYXIS NAUTICA, the Sea Compass, is of course, from its name, a modern constellation, since the instrument from which this asterism derives its title was unknown till the fourteenth century of our era. It is composed of a few stars, none of which exceed the fifth magnitude. Its place in the rigging of the constellation Argo renders its limits a matter of easy dis- crimination. QUADRANT & TELE sco P.E. (P36) (#994) The Comanon. I NS §§ § >k + º º ouazanºvocal:Vargaon ...“ 2 • * | i º 2 T º - ºffſitiº Ayioxºlº 2 * tºw/7/y y \ r wº-vºyſ / w | \, \\// ſ Y | jº, - à º # - * . º {\ *- f lº ſ K / \ º ZA A\ \ y º ſ .4% -- º ſ/ DVT º ,\:W º W g º: º º & 2% d | W §: º -- 23. A2 Q U A Q U A 861 DICTIONARY OF MECHANICAL scIENCE. Q. -* Q, or q, the sixteenth letter of our alphabet. As a numeral it stands for 60; and with a dash over it, thus, Q'för 500,000. Used as an abbreviature, q signifies quantity, or quantum ; thus, among physicians, q. pl. is quantum placet, i. e. as much as you please of a thing ; and q. S. quantum sufficit, i. e. as much as is necessary. Q. E. D. among Mathematicians, is quod erat demonstrandum, i. e. which was to be demonstrated; and Q. E. F. Quod erat faciendum, i. e. which was to be done. Q. D. among Grammarians, is quasi dictum, i. e. as if it was said, or as, who should say. In the notes of the ancients, Q stands for Quintus, or Quintius; Q. B. V. for quod bene vertat ; Q. S. S. S. for qua supra scripta sunt ; Q. M. for Quintus Mu- tius, or quomodo; Quint, for Quintilius ; and Quaºs. for Quaster. QUACK, a person pretending to practise medicine, without having been regularly or properly taught. In its more enlarged sense, this term includes all empirics, particularly those in divinity and law ; but it is more generally restricted to those who, without an adequate degree of learning and knowledge, make pretensions to the healing art. QUACKILTO, in Ornithology, the name of a beautiful Brazilian bird of the moor-hen kind. Its colour is of a fine blackish purple, variegated with white; and it imitates the crow- ing of the common cock. QUADRANGLE, in Geometry, the same with a quadrila- teral figure, or one consisting of four sides and four angles. QUADRANS, the quarter or fourth part of any thing, parti- cularly the Roman as, or pound. QUADRANT, in Geometry, is either the quarter or fourth part of a circle, or the fourth part of its circumference; the arch of which, therefore, contains 90 degrees. - QUADRANT, also denotes a mathematical instrument, of great use in astronomy and navigation, for taking the altitudes of the sun and stars, as also taking angles in surveying heights and distances. There are several kinds of quadrants, which are commonly distinguished from each other, either by the names of their authors, or the purposes they are intºnded to answer. Thus we have Adams's, Cole's, Davis's, Gunter’s, Hadley's, &c. QUADRANts; as also the Astronomical, Surveying, &c. QUAD- RANTs. The principle upon which the construction and use of this instrument depends, may be illustrated by the annexed figure; A B C is a quarter circle of brass wood, or such like, having the arc A B divided into degrees and mi- nutes, from A to B; on one side B C are fixed two sights a, b, and at C is fixed a plumb-line C P. Now to use the instrument, hold it so that the side of the quadrant B C is in a line with the object S, whose elevation is required, or so that it may be seen through the two small sights a, b ; then the degrees, &c. cut off by the plumb- line C P, measured from A towards B, will be the measure of the angle of elevation D BS, required for D B C, being a right- angled triangle, the two angles D B C and B C D, are together equal to a right angle, as are also the two B C D and D C A ; from each of these therefore, taking away the common angle B C D, and there remains the angle D C A equal to the angle D B.A. This is the most simple form of the quadrant, under which it is necessarily subject to very considerable inaccura- cies, to remedy which a variety of forms have been given to it by different authors; but that of Hadley’s is so decidedly supe- rior to any other of a portable kind, that we shall limit our remarks principally to the description and use of this instru- ment; and a slight account of the astronomical and Gunter quadrants. Before we attempt to describe the exact construction of this instrument, it may be of some use to the reader to illustrate the Pºles on which it rests, by a less complex figure than that of | + S the quadrant itself. Though this in- strument is usually called a quadrant, it is, in fact, but an octant, or 8th part of a circle, as QB R, having a label or index B M moveable about B as a centre, and on this index, and in the same direction, is fixed a plane reflecting mirror, and on the side B R is placed another parallel to the other side B Q, but this is silvered only half way up, so that an object O may be seen directly through the plain part of the glass, from E, the sight vane. Now, an observer wish- ing, for example, to measure the angle subtended at H by the two ob- jects OS, looks through the sight vane at E, and moves the index B M about its centre, till the reflected image of S is seen in the other reflector D, previously in conjunction with the object O, as seen through the plain glass; then the angle Q B M, or the arc Q M = } / SHO, as may be thus demonstrated. - Since the angle of incidence is equal to the angle of reflec- tion, Z. A B S = Z. D B G = Z HB G ; therefore B G bisects the angle H B D. Again, for the same reason, Z CD B = Z. H D G = Z. O D C ; therefore D C bisects the angle O D B. Now, Z. O D B = Z. D B H + Z B HD, being the external angle of the triangle D B H, therefore Z C D B = } Z_D B H + 3 Z D H B = Z. D B G + 3 Z D H B ; but Z. C D B = Z. D B G + / D G B, therefore Z D G B = } / D H B, or since C G and B Q are parallel, and Z. D G B = Z. Q B G, the angle Q B G, or QB M, is also equal to half D H B, or half OHS, which was to be shewn. This is the principle on which the construction, and use of this instrument depends; but its great and extensive utility in astronomical and nautical observations, renders it necessary now to enter into a more minute description. It may be observed, that in consequence of the points H and E not coin- ciding, there is a small error E H between the true and appa- rent angular point, which is called the parallaw of the instru- ment ; this, however, is zero, in celestial observations. The Astronomical QUADRANT, is a large one, usually made of brass or iron bars; having its limb EF, fig. 1, (Plate Quadrants,) nicely divided, either diagonally or otherwise, into degrees, minutes, and seconds, if room will permit, and furnished either with two pair of plain sights or two telescopes, one on the side of the quadrant at A B, and the other C D moveable about the centre by means of the screw G. The dented wheels I and H serve to direct the instrument to any object or phenomenon. The application of this useful instrument, in taking observa- tions of the sun, planets, and fixed stars, is obvious ; for being turned horizontally upon its axis, by means of the telescope A B, till the object is seen through the moveable telescope, then the degrees, &c. cut by the index, give the altitude, &c. required. e Description of Hadley's QUADRANT-This instrument consists of the following particulars; see plate, fig. 2. 1. An octant, or the eighth part of a circle, A B C. 2. An index D. 3. The speculum F. 4. Two horizontal glasses, F, G, 5. Two screens, K and K. 6. Two sight vanes, H and I. - The octant consists of two radii AB, AC, strengthened by the braces L., M, and the arch B C ; which, though containing only 45°, is nevertheless divided into 90 primary divisions, each of which stands for degrees, and are numbered 0, 10, 20, 30, &c. to 90; beginning at each end of the arch, for the convenience of numbering both ways, either for altitudes or zenith distances; also each degree is subdivided into minutes, by means of a vernier. But the number of these divisions varies with the size of the instrument. - - The index D is a flat bar, moveable about the centre of the 10 K. 862 Q U. A Q U. A DICTIONARY OF MECHANICAL SCIENCE. instrument; and that part of it which slides over the graduated areh BC, is open in the middle, with a vernier scale on the lower part of it, under which is a screw serving to fasten it per- pendicular to the plane of the instrument, the middle part of the former coinciding with the centre of the latter; and because the speculum is fixed to the index, the position of it will be altered by moving the index along the arch. The rays of an observed object are received on the speculum, and from thence reflected on one of the horizon glasses F or G ; which are two small pieces of looking glass placed on one of the limbs, their faces being turned obliquely to the speculum, from which they receive the reflected rays of objects. This glass F has only its lower part silvered, and set in brass-work, the upper part being left transparent, to view the horizon. The glass G has, in its middle, a transparent slit, through which the horizon is to be seen. And, because the warping of the materials, and other accidents, may distend them from their true situation, there are three screws passing through their feet, by which they may be easily replaced. The screens are two pieces of coloured glass, set in two square brass frames, K and K, which serve as screens to take off the glare of the sun's rays, which would otherwise be too strong for the eye: the one is tinged much deeper than the other; and as they both move on the same centre, they may be both or either of them used : in the situation they appear in the figure, they serve for the horizontal glass F; but when they are wanted for the horizon glass G, they must be taken from their present situation, and placed on the quadrant above G. The sight-vanes are two pins H and I, standing perpendicu- lar to the plane of the instrument: that at H has one hole in it, opposite to the transparent slit in the horizon glass G ; the other, at I, has two holes in it, the one opposite to the middle of the transparent part of the horizon glass F, and the other rather lower than the quicksilvered part: this vane has a piece of brass on the back of it, which moves round a centre, and serves to cover either of the holes - - To rectify Hadley's Quadrant. For the Fore Observation.— Bring the index close to the bottom, so that the middle of the vernier's scale, or monius, stand against 0 degrees. Hold the plane of the instrument vertical with the arch downwards; look through the right-hand hole in the vane, and direct the sight through the transparent part of the horizon glass, to observe the horizon. If the horizon, seen both at the quick- silvered part, and through the transparent part, should coin- cide, or make one straight line, then is the glass adjusted ; but if one of the horizon lines should stand above the other, slacken the screw in the middle of the lever backwards or forwards, as there may be occasion, until the lines coincide; fasten the screw in the middle of the lever, and all is ready for use. To take the Sun's Altitude.—Fix the screens above the hori- zon glass, using either or both of them, according to the strength of the sun's rays, by turning one or both the frames of those glasses close against the plane or face of the instrument; then your face being turned towards the sun, hold the quadrant by the braces, or by either radius, as is found most convenient, so as to be in a vertical position, with the arch downwards. Put the eye close to the right-hand hole in the vane, look at the horizon through the transparent part of the horizon glass, at ths same time sliding the index with the left hand, until the image of the sun, seen in the quicksilvered part, falls in with the edge of the horizon, taking either the upper or the under edge of the solar image. Swing your body gently from side to side; and when the edge of the sun is observed not to cut, but to touch the horizon line, like a tangent, the observation is made. Then will the degrees on the arch, reckoning from the end next your body, give the altitude of that edge of the sun which was brought to the horizon. If the lower edge was observed, then sixteen minutes, added to the said degrees, gives the altitude of the sun's centre; but if the upper cdge was used, the sixteen minutes must be subtracted. To take the Altitude of a Star.—Look directly up at the star through the vane and transparent part of the glass, the index being close to the button; then will the image of the star, by reſlection, be seen in the silvered part, right against the star seen through the other part. Move the index forward, and as the image descends, let the quadrant descend also, to keep it - l in the silvered part, till it comes down in a line with the hori- ſº seen through the transparent part, and the observation is In a Cl6, 1 To rectify the Instrument for the Back Observation.—Slacken the screw in the middle of the handle, behind the glass G ; turn the button h on one side, and bring the index as many degrees before 0 as is equal to double the dip of the horizon at your height above the water; hold the instrument vertical, with the arch downwards; look through the hole of the vane H ; and if the horizon, seen through the transparent slit in the glass G, coincide with the image of the horizon seen in the silvered part of the same glass, then the glass G is in its proper position; but if not, set it by the handle, and fasten the screw as before. To take the Sun's Altitude by the Back Obscrvation.—Put the stem of the screens K and K into the hole r, and in proportion to the strength or faintness of the sun's rays, let either one, or both, or neither of the frames of those glasses, be turned close to the face of the limb ; hold the instrument in a vertical posi- tion with the arch downward, by the braces L and M, with the left hand; turn your back to the sun, and put one eye close to the hole in the vane H, observing the horizon through the trans- parent slit in the horizon glass G.; with the right hand move the index D, till the reflected image of the sun be seen in the silvered part of the glass G, and in a right line with the horizon; swing your body to and fro, and if the observation be well made the sun's image will be observed to brush the horizon, and the degrees reckoned from C, or that part of the arch farthest from your body, will give the sun's altitude, at the time of observ- ation ; observing to add 16 for the sun's semidiameter, if the . upper edge be used, and subtract the same for the lower edge. - - The directions just given, for taking the altitudes at sea, would be sufficient, but for two corrections that are necessary to be made before the altitude can be accurately determined, viz. one on account of the observer's eye being raised above the level of the sea, and the other on account of the refraction of the atmosphere, especially in small altitudes. The following tables therefore shew the corrections to be made on both these accounts; the first referring to the dip of the horizon; and the other to the refraction in altitude ; the method of using which is given, in the following column. TABLE I.—Dip of the Horizon. Height of Height of |Height of - the Eye DIP the Eye DIP. the Eye | DIP. in Feet. t in Feet. in Feet. } I 0. 57" 12 3' 18" 35 5' 39" 2 1 21 Si4 3 24 40 6 2 3 1 39 16 3 47 45 6 24 4 1 55 18 4 3 50 6 44 5 2 8 20 4 16 60 7 23 6 2 20 22 4, 28 70 7 29 7 2 31 24 4 40 80 8 32 8 2 42 26 4 52 | 90 9 3 9 2 52 28 5 3 100 9 33 10 3 1 30 5 14 - TABLE II.-Refraction in Altitude. Apparent * Apparent || e Apparent - Altitude in Refraction. || Altitude in liſtefraction. Altitude in | Refraction. Degrees. Degrees. l)egrees. 0 33' 0" 8 6, 29" 40 1' 8" # 30 35 9 5 48 || 45 () 57 # 28 22 10 5 15 50 0 48 1. 24, 29 1 1 4 47 55 0 40 "2 18 35 12 4, 23 60 0 33 3 14 36 || 15 3 30 || 65 0 26 4 ll 51 20 2 35 70 () 21 5 9 54 2ſ, 2 2 75 0 15 6 8 29 30 T 38 80 0 10 7 7 20 35 1 21 85 0. 5 Q U A Q U A 863 DICTIONARY OF MECHANICAL SCIENCE. A General Rules for the Corrections.—l. In the fore observations, add the sum of both corrections to the observed zenith distance, for the true zenith distance; or subtract the said sum from the . observed altitude for the true one. 2. In the back observation, add the dip and subtract the refraction for altitudes; and for zenith distances, do the contrary, viz. Subtract the dip and add the refraction. Exam. By a back observation the altitude of the sun's lower edge was found by Hadley's quadrant to be 25° 12"; the eye being 30 feet above the horizon. By the tables the dip on 30 feet is 5' 14", and the refraction on 25°12' is 2' 1". Hence Apparent alt. lower limb.................. 25°12' 0" Sun's semidiameter, sub. . . . . . . . . . . . . . . . . 0 16 0 Appar, alt. of centre . . . . . . . . . ............ 24 56 0 Dip of horizon, add. . . . . . e e º 'º e s e e s e e º e s e e 0 5 14 25 1 14 Refraction subtract. . . . . . . . . . . . . . . . . . . . . . . . 0 2 1 True alt. ofcentre........................ 24 59 13 In the case of the moon, besides the two corrections above another is to be made for her parallax. But for all these par- ticulars, see the requisite tables for the Nautical Almanac, &c. QUADRANT, the Common or Surveying. This instrument, ABC fig. 3, is made of brass, or wood, &c.; the limb or arch of which B C is divided into 90 deg. and each of these is farther divided into as many equal parts as the space will allow, diagonally o. otherwise. To one of the radii A. C. are fitted two moveable sights; and to the centre is sometimes also annexed a label, or moveable index A D, bearing two other sights; but instead of these last sights there is sometimes fitted a telescope. Also from the centre hangs a thread with a plummet; and on the under side or face of the instrument are fitted a ball and socket, by means of which it may be put into any position. The gene- ral use of it is for taking angles in a vertical plane, compre. hended under right lines going from the centre of the instrument one of which is horizontal, and the other is directed to some visible point. But besides the part above described, there is often added, on the face, near the centre, a kind of compart- ment E F, called a quadrant or geometrical square, which is a kind of separate instrument, and is particularly useful in alti- metry and longimetry, and measuring heights and distances. QUADRANT, Cole's, is a very useful instrument, invented by Mr. Benjamin Cole. It consists of six parts, viz. the staff AB, fig. 4; the quadrantal arch D E ; three vanes A, B, C ; and their vernier F G. The staff is a bar of wood about two feet long, an inch and a quarter broad, and of a sufficient thickness to prevent it from bending or warping. The quadrantal arch is also of wood, and is divided into degrees or third parts of de- grees, to a radius of about nine inches; and to its extremities are fitted two radii, which meet in the centre of the quadrant by a pin, about which it easily moves. The sight-vane A is a thin piece of brass, near two inches in height and one broad, set perpendicularly on the end of the staff, A, by means of two screws passing through its foot. In the middle of this Vane is drilled a small hole, through which the coincidence or meeting of the horizon and solar spot is to be viewed. The horizontal vane B is about an inch broad and two inches and a half high, having a slit cut through it of near an inch long and a quarter of an inch broad; this vane is fixed in the centre-pin of the instrument, in a perpendicular position by means of two screws passing through its foot, by which its position with respect to the sight-vane is always the same, their angle of inclination being equal to 45 degrees. The shade-vane C is composed of two brass plates. The one which serves as an arm is about 4% inches long and 3 of an inch broad, being pin- ned at one end to the upper limb of the quadrant by a screw, about which it has a small motion; the other end lies in the arch, and the lower edge of the arm is directed to the middle of the centre pin. The other plate, which is properly the vane, is about two inches long, being fixed perpendicularly to the other plate at about half an inch distance from that end next the arch ; this vane may be used either by its shade, or by the solar spot cast by a convex lens placed in it. And because the wood work is often subject to warp or twist, therefore this vane may be rectified by means of a screw, so that the warping of the instrument may occasion no error in the observation, which is performed in the following manner: set the line G on the vernier against a degree of the upper limb of the quadrant; and turn the screw on the back side of the limb, forward or back- ward, till the hole in the sight-vane, the centre of the glass and the sunk spot in the horizon-vane, lie in a right line. QUADRANT, Collins's or Sutton's, fig. 5, is a stereographic pro- jection of one quarter of the sphere between the tropics, upon the plane of the ecliptic, the eye being in its north pole; and fitted to the latitude of London. The lines running from right to left, are parallels of latitude; and those crossing them are azimuths. The smaller of the two circles bounding the pro- jection is one quarter of the tropic of Capricorn; and the great- er is a quarter of the tropic of Cancer. The two ecliptics are drawn from a point on the left edge of the quadrant, with the characters of the signs upon them; and the two horizons are drawn from the same point. The limb is divided both into degrees and time; and by having the sun's altitude, the hour of the day may here be found to a minute. The quadrantal arches next the centre contain the calendar of months; and under them, in another arch, is the sun’s declination. On the projection are placed several of the most remarkable fixed stars between the tropics, and the next below the projection are the quadrant and line of shadows. QUADRANT, Gunner's, fig. 6, sometimes called gunner's square, is used for elevating and pointing cannon, mortars, &c. and consists of two branches either of wood or brass, between which is a quadrantal arch divided into 90 deg. and furnished with a thread and plummet. ... • - QUADRANT, Gunter’s, so called from its inventor, Edmund Gunter, (fig. 7,) besides the apparatus of other quadrants, has a stereographic projection of the sphere on the plane of the equinoctial; and also a calendar of the months, next to the divisions of the limb ; by which, besides the common purposes of other quadrants, several useful questions in astronomy are easily resolved. * - Sinical QUADRANT, is one of some use in navigation. It con- sists of several concentric quadrantal arches, divided into eight equal parts by means of radii, with parallel right lines crossing each other at right angles. Now any one of the arches, as nate in H, allowing every small interval four leagues. B C, fig. 8, in the Plate, may represent a quadrant of any great circle of the sphere, but is chiefly used for the horizon or meri- dian. If then B C is taken for a quadrant of the horizon, either of the sides, as A B, may represent the meridian, and the other side A C will represent a parallel, or line of east and west; all the other lines parallel to A B will be also meridians; and all those parallel to AC, east and west lines, or parallels. Again, the eight species into which the arches are divided by the radii, represent the eight points of the compass in a quarter of the horizon; each containing 11 deg. 15 min. The arch BC is likewise divided into 90 deg., and each degree subdivided into 12 min., diagonal wise. To the centre is fixed a thread, which being laid over any degree of the quadrant, serves to divide the horizon. If the sinical quadrant is taken for a fourth part of the meridian, one side of it, A B, may be taken for the common radius of the meridian and equator; and then the other, A C, will be half the axis of the world. The degrees of the circumference, B C, will represent degrees of latitude : and the parallels to the side, A B, assumed from every point of latitude to the axis, A C, will be radii of the parallels of lati- tudes, as likewise the cosine of those latitudes. Hence, sup- pose it is required to find the degrees of longitude contained in 83 of the lesser leagues in the parallel of 48 deg. ; lay the thread over 48 deg. of latitude on the circumference, and count thence the 83 leagues on A B, beginning at A ; this will ". CIA tracing out the parallel H E, from the point H to the thread, the part A E of the thread shews that 125 greater or equinoctial leagues make 6 deg. 15 min. ; and therefore that the 83 lesser leagues A H, which make the difference of longitude of the course, and are equal to the radius of the parallel H.E, make 6 deg. 15 min. of the said parallel. When the ship sails upon an oblique course, such course, besides the north and south greater leagues, gives lesser leagues easterly and westerly, to be re. 864. Q U A Q U A DICTIONARY OF MECHANICAL SCIENCE. duced to degrees of longitude of the equator. But these lea- | gues being made neither on the parallel of departure, nor on that of arrival, but on all the intermediate ones, there must be found a mean proportional parallel between them. To find this, there is on the instrument a scale of cross latitudes. Suppose then it were required to find a mean parallel between middle point will terminate against the first degree, which is the mean parallel sought. The chief use of the sinical quad- rant is, to form upon it, triangles similar to those made by a ship's way with the meridians and parallels; the sides of which triangles are measured by the equal intervals between the con- centric quadrants and the lines N and S E and W.; and every 5th line and arch are made deeper than the rest. Now sup- pose a ship has sailed 150 leagues, north-east by north, or making an angle of 33 deg. 45 min. with the north part of the meridian ; here are given the course and distance sailed, by which a triangle may be formed on the instrument similar to that made by the ship's course; and hence the unknown parts of the triangle may be found. Thus, supposing the centre A to represent the place of departure, count by means of the con- centric circles along the point the ship sailed on, viz. A A D, 150 leagues; then in the triangle A E D, similar to that of the ship's course, find A E = difference of latitude, and DE = diſſerence of longitude, which must be reduced according to the parallel of latitude come to. e QUADRANT and Practical Navigator. This newly-invented instrument has been described in the “Mechanics’ Magazine.” We presume, if it were completely made, it would be found very useful at sea for navigation, as any man might soon un- derstand it; and also for many mechanics and schoolmasters, for demonstrating problems in some branches of the mathe- matics. Description.—A B C D, fig.9, in the Plate, represents a plain piece of board, with a place in the middle, pp, for the slide, A, to move up and down in. º scale B. By enlarging this quadrant to a semicircle, Q Q, the scales B and C, turning upon a centre, will set to solve all questions in oblique as well as plane trigonometry. B will turn off from scale A to any distance, as at L, the pricked line; and by sliding A upwards or downwards in the board, the scales will set to the given dimensions of any triangle what- ever, and give both the plane and the true contents of all parts at the same time. By raising scale B to the pricked line, M, by a plummet hung at the centre, it becomes a good level; it will also give all the dimensions of a square. If you set slide A to the dimensions of one side of a square, set slide C to the same dimensions in the bottom scale, and C becomes the dia- gonal of the square. I have solved all the problems of prac- tical navigation by this instrument, and a great number of pro- miscuous questions, with great ease and accuracy. The second horizontal line, C, and that next above it, represent a groove, wherein a quadrant, Q Q, slides, divided as the preceding; and by having two quadrants and the four scales to move upon the board A B C D, there will in all cases be three slides and two angles, which, I presume, will solve any question that can be proposed. QUADRANT of Altitude, is an appendix to the artificial globe, consisting of a thin slip of brass, the length of a quarter part of one of the great circles of the globe, and graduated. At the end, where the division terminates, is a nut riveted on, and furnished with a screw, by means of which the instrument is fitted on the meridian, and moveable round upon the rivet to all points of the horizon. Its use is to serve as a scale in measuring of altitudes, amplitudes, azimuths, &c. QUADRANTAL, in Roman antiquity, a vessel every way square like a die, serving as a measure of liquids; its capacity was eighty librae or pounds of water, which make 48 sextaries, two urnaº, or eight congii. QUADRANTAL Triangle, a spherical triangle having a quadrant or an arc of 90° for one of its sides. QUADRAT, in Printing, a piece of metal cast like the let- ters, to fill up the void spaces between words, &c. There are m quadrats, n quadrats, &c. which are respectively of the dimensions of these letters. - - Q is a quadrant made fast upon lish cock, and may be brought to fight like game cocks. was much practised among the Athenians, and is still kept up QUADRAT, a mathematical instrument, called also a geo- metrical square, and a line of shadows; it is frequently an addi- tional member on the face of the common quadrant, as also on those of Gunter's and Sutton's quadrant; but we shall describe it by itself, as being a distinct instrument. solid matter, as brass, wood, &c. of any four plain rules joined the parallels of 40 deg. and 60 deg.: take with the compasses | the middle between the 40th and 60th degree on the scale; this It is made of any together at right angles, where A is yº _* the centre, from which hangs a thread - with a small weight at the end, serv- ing as a plummet. Each of the sides B E and DE, is divided into an hun- - dred equal parts; or if the sides be long enough to admit of it, into a thousand parts; C and F are two sights T - B fixed on ; tº: . º: º over, an index, GH, which, when there \" = i is occasion, is joined to the centre A, Tº in such a manner as that it can move freely round, and remain in any given situation; there are also two sights KL, perpendicular to the right line going from the centre of the instrument. The side D E is called the upright side, or the line of the direct or upright shadows; and the side B E is termed the reclined side, or the line of the versed or back shadows. QUADRATURE, in Astronomy, that aspect of the moon when she is 90 deg. distant from the sun; or when she is in the middle point of her orbit, between the points of conjunction and opposition, namely, in the first and third quarters. QUADRATURE Lines, are two lines placed on Gunter’s sector: they are marked with Q. and 5, 6, 7, 8, 9, 10: of which Q. sig- nifies the side of the square, and the other figures the side of the polygons of 5, 6, 7, &c. sides. S, on the same instrument, stands for the semi-diameter of a circle, and 90 for a line equal to 90 deg. in circumference. QUADRILLE, a game at cards, sometimes called ombre by four ; which chiefly differs from ombre by three, in being played by four persons; and having all the forty cards dealt out to each person, at ten each. - QUADRUPEDS, in Zoology, a class of land animals, with hairy bodies, and four limbs or legs proceeding from the trunk of their bodies; add to this, that the females of this class are viviparous, or bring forth their young alive, and nourish them with milk from their teats. - QUADRUPLE, a sum or number multiplied by four, or taken four times, t QUAGMIRE, in Agriculture, the name of a soft, miry, or shak- ing bog, swamp, or morass, which is frequently met with in low hollow situations, which affords but little declivity for the dis- charge of stagnant water. QUAIL, in Ornithology, the least of all the birds of the gal- linaceous kind. They have, however, the courage of the Eng- This in some parts of Italy and Asia. The quail is a bird of pas- sage, takes up its abode in corn fields, begins to sing in April, make its nest in May on the ground, and lays six or seven whitish eggs, marked with ragged rust-coloured spots. QUAKERS. By stat. 7 and 8 W. III. c. 27, and 8. G. ſ. c. 6, Quakers making and subscribing the declaration of fidelity mention.cd in 1 W. and M. shall not be liable to the penalty against others refusing to take such oaths: and not subscrib- ing the declaration of fidelity, &c. they are disabled to vote at the election of members of parliament. By 7 and 8 W. III. c. 4, made perpetual by 1 G. I. c. 6, Quakers, where an oath is required, are permitted to make a solemn affirmation or decla- ration of the truth of any fact; but they are not capable of being witnesses in any criminal cause, serving on juries, or bearing any office or place of profit under government, unless they are sworn like other Protestants: but this clause does not extend to the freedom of a corporation. By stat. 22 G. II. c. 46, an affirmation shall be allowed in all cases (except criminal) where by any act of parliament an oath is required, though no provision is therein made for admitting a Quaker to make his affirmation. With respect to doctrine, Quakers are much divided : some being unitarians, and others believing the trinity. Q U A Q U A 865 DICTION ARY OF MECHANICAL SCIENCE. QUALITY, that affection of a thing whence its denomina- tion is derived. Hence, quality is said to be an attribute from which no substance is exempt. Qualities are of various kind, physical, intellectual, moral, primary, secondary, essential, relative, active, passive, &c. The term is applicable to animate and inanimate being. • QUANTITY, in Grammar, an affection of a syllable, whereby its measure, or the time wherein it is pronounced, is ascer- tained; or that which determines the syllable to be long or short. Quantity is also the object of prosody, and distin- guishes verse from prose; and the economy and arrangement of quantities, that is, the distribution of long and short syl- lables, make what we call the number. The quantities are dis- tinguished, among grammarians, by the characters 8, short, as per; and 5, long, as ros. There is also a common, variable, or dubious quantity ; that is, syllables that are one time taken for short ones, and at another time for long ones; as the first syl- lable in atlas, patres, &c. Feet are made up of quantities. The quantity of syllables is known two ways. 1. By rules for that purpose. taught by that part of grammar called prosody ; the authority made use of in this case is no more than examples from, or the testimony of, approved authors; and is never used but either when the rules are deficient, or when we are unacquainted with them. • QUANTUM VALEBANT, is where goods and wares sold are delivered by a tradesman at no certain price, or to be paid for them as much as they are worth in general ; and the plaintiff is to aver them to be worth so much. QUANTUM Merwit, in Law, is an action upon the case, founded on the necessity of paying a person for doing any thing as much as he deserves. * QUARANTINE, a trial which ships undergo when suspected of having on board persons infected with a pestilential disease. Physicians are occasionally consulted on this subject by govern- ment; who regulate this unpleasant restriction on the commerce of the country by their judgment, as to the period of time within which the effects of any infection, received by any individual on board, would be shewn. The usual quarantine is forty days. This may be ordered by the king, with the advice of the privy- council, at such times, and under such regulations, as he judges proper. Ships ordered on quarantine must repair to the place appointed, and must continue there during the time prescribed, without having any intercourse with the shore, except for neces- sary provisions, which are conveyed with every possible pre- caution. When the time is expired, and the goods opened and exposed to the air as directed, if there be no appearance of infection, they are admitted to port. Ships infected with the pestilence must proceed to St. Helen's Pool in the Scilly islands, and give notice of their situation to the custom-house officers, and wait till the king’s pleasure be known. Persons giving false information, to avoid performing quarantine, or refusing to go to the place appointed, or escaping; also officers appointed to see quarantine performed, deserting their office, neglecting their duty, or giving a false certificate; suffer death as felons. Goods from Turkey or the Levant may not be landed without license from the king, or certificate that they have been landed and aired at some foreign port. QUARE, in Law, a term affixed to the title of several writs. QUARRY, the common name of an opening or pit dug into the earth, from which slate, marble, stones, and ores of various kinds, are to be raised, for purposes to which they are ap- plicable. QUARTER, in Law, the fourth part of a year; and hence the days on which these quarters commence are called quarter- days, viz. March 25, or Lady-day ; June 24, or Midsummer- day; September 29, or Michaelmas; and December 21, or St. Thomas the Apostle's day. On these days rents on leases, &c. are usually reserved to be paid ; though December 25, or Christmas-day, is commonly reckoned the last quarter-day. QUARTER, the fourth part of any thing, the fractional expres- sion for which is #. Quarter in weights, is generally used for the fourth part of a hundred weight avoirdupois, or 28 lb. Used as the name of a dry measure, quarter is the fourth part of a ton in weight, or eight bushels. QUARTER, in Heraldry, is applied to the parts or members 88. ‘. And, 2. By authority. The rules for this end are | nated by the quarter-pieces. of the first division of a coat that is quartered, or divided into four quarters. QUARTER of a Point, in Navigation, is the fourth part of the distance between two cardinal points, which is 2 deg. 48. min. QUARTER, that part of a ship's side which lies towards the stern, or which is comprehended between the aft-most end of the main chains, and the sides of the stern, whence it is termi- Although the lines by which the quarter and bow of a ship, with respect to her lengths, are only imaginary, yet experience appears sufficiently to have ascer- tained their limits; so that if we were to divide the ship's sides into five equal portinos the names of each space would be rea- dily enough expressed; thus the first from the stern would be the quarter; the second, abaft the midships; the third, the mid- ships; the fourth, before the midships; and the fifth, the bow. On the QUARTER, may be defined a point in the horizon, con- siderably abaft the beam, but not in the direction of the ship's stern. See the article Bea RING. - QUARTER Bill, a list, containing the different stations to which the officers and crew are quartered in time of battle, with the names of the persons appointed to those stations. QUARTER Clothes, long pieces of painted canvass, extended on the outside of the quarter-netting, from the upper part of the gallery to the gangway. - QUARTER Gallery. See GALLERY. QUARTER Master, in the Navy, an inferior officer appointed to assist the mates in their several duties, as stowing the hold, soiling the cables, attending the steerage, and keeping time by the watch-glasses. QUARTER Master's Mate, an officer under the preceding. QUARTER-Rails, are narrow moulded planks, reaching from the top of the stern to the gangway, and serving as a fence to the quarter-deck. . * QUARTERING, in Gunnery, is when a piece of ordnance is so traversed that it will shoot on the same line, or on the same point of the compass, as the ship's quarter bears. QUARTERING, in Heraldry, in dividing a coat into four or more quarters or quarterings, by parting, couping, &c. that is, by perpendicular and horizontal lines, &c. - - QUARTERS, imply the several stations where the officers and crew of a ship of war are posted in time of action. See the articles BATTLE, ENGAGEMENT, &c. The lieutenants are gene- rally quartered on the different decks, to command the batteries; the master superintends the management of the ship ; the boat- swain and a sufficient number of men, are stationed to repair the damaged rigging; the gunner, usually on the lower gun-deck, and the carpenter, with his mates and crew, in the wings on the orlop. The marines are generally quartered on the poop and forecastle, or gangway, under the direction of their officers, although, on some occasions, they assist at the great guns, par- ticularly in distant cannonading ; and the great body of the seamen are stationed at the cannon or in the tops ; while the captain is ever on the quarter-deck, giving directions to all around, and animating every one by his example. The number of men appointed to manage the artillery is always in proportion to the nature of the guns, and the num- ber and condition of the ship's crew. They are in general as follow, when the ship is full manned, so as to fight both sides at once occasionally : Nature of the Guns :-To a 42-pounder, 15 men; to a 32, 13 men; to a 24, 11 men ; to a 18, 9 men; to a 12, 7 men; to a 9, 6 men ; to a 6, 5 men; to a 4, 4 men ; to a 3, 3 men. This number, to which is often added a boy, to bring powder to every gun, may be occasionally reduced, and the guns nevertheless well managed. The number of men ap- pointed to the small arms:—1st rate 150 men to the small arms; 2d rate, 120 ditto; 3d rate of 80 guns, 100 ditto: 3d rate of 70 guns, 80 ditto; 4th rate of 60 guns, 70 ditto; 4th rate of 50 guns, 60 ditto; 5th rate, 50 ditto; 6th rate, 40 ditto; sloops of war, 30 ditto. - * QUARTERs, is also an exclamation to implore mercy from a victorious enemy. - QUARTERs of the Yards, the space comprehended between the slings or middle, and the outer parts or the yard-arms. QUARTER Tackle, a strong tackle fixed occasionally upon the quarter of the main-yard, to hoist heavy bodies in or out of the ship. - 10 L 866 Q U O Q U I DICTIONARY OF MECHANICAL SCIENCE. QUARTER-SESSIONS. The sessions of the peace is a court of record holden before two or more justices, whereof one is of the quorum, for the execution of the authority given them by the commission of the peace, and certain statutes and acts of parliament. The justices keep their sessions in every quarter of the year at least, and for three days if need be ; to wit, in the first week after the feast of St. Michael, in the first week after the Epiphany, in the first week after Easter, and in the first week after St.Thomas, and oftener if need be. Any two justices, one whereof is of the quorum, by the words of the commission of the peace, may issue their precept to the sheriff, 'to summon a session for the general execution of their autho- 'rity; and such session, holden at any time within that quarter of a year, is a general quarter-session, and the sheriff must summon a jury under their authority. There are many offences, which, by particular statutes, belong properly to this jurisdic- tion, and ought to be prosecuted in this court, as the smaller misdemeanors, not amounting to felony, and especially offences relating to the game laws, highways, alehouses, bastard chil- dren, the settlements and provision of the poor, vagrants, ser- vants' wages, apprentices, and popish recusants. Some of these are proceeded upon by indictment, and others in a sum- mary way, by motion and order, which may, for the most part, unless guarded against by any particular statute, be removed into the Court of King's Bench by certiorari, and be there either quashed or confirmed. The business done at quarter sessions has become of the highest importance to the country, and the public are greatly indebted to those magistrates who have sufficient knowledge of law to perform the duties Of their office and give their attendance. In Ireland a practising barrister is appointed at each session to assist as chairman. In England this is not generally the case by law, but barristers are chiefly preferred, and the duty to be performed is so multifarious, that it requires no small skill in law, accompanied with much acti. vity and industry, to execute it justly. QUARTZ, a mineral of the flint genus, which is divided into five sub-species: viz. the amethyst, the rock-crystal, milk- quartz, common quartz, and prase. QUASSIA, a genus of the monogynia order, in the decandria class of plants, and in the natural method ranking under the 14th order, gruinales. The calyx is pentaphyllous; there are five petals; the nectarium is pentaphyllous ; there are from two to five seed-cases, standing asunder, and monospermous. There are three species, the amara, simaruba, and excelsa. The different species are much used in medicine, and by the brewers, to give a bitter taste to their beer. QUAY, or Key, a place to land goods upon. QUEEN, a woman who holds a crown singly. The title of queen is also given by way of courtesy to her that is married to a king, who is called by way of distinction queen-consort. QUERCITRON, in Dying, the internal bark of the quercus migra; it yields its colour, which is yellow, by infusion in water, and by the common mordants gives a permanent dye. See DYEING. QUERCUS, in Botany, the Oak-tree, a genus of the monoecia polyandria class and order. The wood of the oak, when of a good sort, is well known to be hard, tough, tolerably flexible, not easily splintering, strong without being too heavy, and not easily admitting water; for these qualities it is preferred to all other timber for building ships; it would be difficult to enume- rate all the uses to which it may be applied. Oak saw-dust is the principle indigenous vegetable used in dyeing fustian ; all the varieties of drabs and different shades of brown are made with oak saw-dust, variously managed and compounded. Oak apples are also used in dying, as a substitute for galls. See CORK. *. - QUICK, or Quickset Hedge, among Gardeners, denotes all live hedges, of whatsoever sort of plants they are composed, to distinguish them from dead hedges; but in a more strict sense of the word, it is restrained to those planted with the hawthorn, or cratagus oxyacantha, under which name these young plants, or sets, are sold by the nursery-gardeners, who raise them for sale. QUICKSAND, a loose sand into which a ship sinks by her own weight, as soon as the water retreats from her bottom. QUICKSILVER. See MERCURY., level, that it may be more truly directed to the object. , QUICKWORK, generally signifies all that part of a ship which is under water when she is laden ; it is also applied to that part of the side which is above the sheer rail. QUILLS, are the large feathers taken out of the end of the wings of geese, ostriches, crows, &c. They are denominated | from the order in which they are fixed in the wing ; the second. and third quills being the best for writing, as they have the largest and roundest barrels. Crow quills are chiefly used for drawing. - - QUILTING, a method of sewing two pieces of silk, linen, or stuff, on each other, with wool or cotton between them ; by working them all over in the form of chequer or diamond work, or in flowers. The same name is also given to the stuff so worked. QUT LTING, the operation of weaving a kind of coating form- ed of the strands of ropes about the outside of any vessel, to contain water, as a jar, bottle, &c. QUINCUNX, in Roman antiquity, denotes any thing that consists of five-twelfth parts of another, but particularly of the as, or pound. QUINCUNX Order, in Gardening, a plantation of trees, dis- posed originally in a square, and consisting of five trees, one at each corner, and a fifth in the middle; or a quincunx is the figure of a plantation of trees, disposed in several rows, both length and breadthwise, in such a manner, that the first tree in the second row commences in the centre of the square formed by the two first trees in the first row, and the two first in the third, resembling the figure of the five at cards. QUINDECAGON, in Geometry, a plane figure with fifteen sides and fifteen angles, which, if the sides are all equal, is termed a regular quindecagon, and irregular when otherwise. The side of a regular quindecagon inscribed in a circle is equal in power to the half-difference between the side of the equilateral triangle, and the side of the pentagon inscribed in the same circle ; also the diſſerence of the perpendiculars let fall on both sides, taken together. QUINTAL, in Commerce, the weight of a hundred pounds. ' QUINTESSENCE, in the ancient chemistry, properly de- noted the fifth essence, or the result of five successive distilla- tions. This term was also used to express the highest degree of rectification to which any substance could be brought. Of late years it has become partially obsolete. QUIPOS, in literary history, a name given knots or cords of various colours in Peru, which imperfectly supplied the place of writing. The different colours denoted distinct objects, and each knot expressed a diſſerent number. QUIRE, of PAPER, a quantity of 24 or 25 sheets. - QUITAM, in Law, is where an action is brought or an inform- ation exhibited, against a person, on a penal statute, at the suit of the king and the party or informer, when the penalty for breach of the statute is directed to be divided between them ; in that case the informer prosecutes as well for the king as 'for himself. - - QUIT-CLAIM, in Law, signifies a release of any action that one person has against another. It signifies also a quitting a claim or title to lands, &c. . QUIT-RENT, in Law, a small rent that is payable by the tenants of most manors, whereby the tenant goes quit and free from all other services. Anciently this payment was called white-rent, on account that it was paid in silver coin, and to distinguish it from rent-corn. QUOIN, a wedge employed to raise the cannon to a proper Also, a small wedge used by printers for fastening their pages in iron chases. QUOI Ns, are also employed to wedge off casks of liquids from each other, that their bilges may not rub so as to occasion a leak by the agitation of the ship at sea. QUOITS, a kind of exercise or game, known among the ancients under the name of discus. QUO MINUS, is a writ which issues out of the court of ex- chequer to the king's farmer or debtor, for debt, trespass, &c. Though this writ was formerly granted only to the king's tenants or debtors, the practice now is become general for the plaintiff to surmise, that by the wrong the defendant does him, he is the less able to satisfy his debt to the king, by which means Q U O Q U O 867 DICTIONARY OF MECHANICAL SCIENCE. jurisdiction is given to the court of exchequer to determine the cause. This writ is to take the body of the defendant, in like manner as the capias in the common pleas, and the writ of lati- tat in the king's bench. - QUORUM, a word which often occurs in our statutes, and is much used in commissions, both of justices of the peace and others, and so called from the words of the commission, quorum unum esse volumus, of whom we wish that A, B, &c. should be one. Aſ I magistrates are now of the quorum. - QUO WARRANTO, in Law, a writ which lies against a person or corporation that usurps any franchise or liberty against the king; as to have a fair, market, or the like, in order to oblige the usurper to shew by what right and title he holds or claims such franchise. This writ also lies formis-user or non-user of privileges, granted. The attorney general may exhibit a quo-warranto in the crown office against any particu- lar persons, or bodies politic or corporate, who use any fran- chise or privilege without having a legal grant or prescription for the same, and a judgment obtained upon it is final, as being a writ of right. - z' R. R A D R. the seventeenth letter of our alphabet. In the notes of the ancients, R. or R O signifies Roma; R. C. Romana civitas; R. G. C. reigerendae causa; R. F. E. D. recte fractum et dictum ; R. F. regis filius; R. P. res publica, or Romani principes; and R. R. R. F. F. F. res Romana ruet ferro, ſame, flamma. In the prescription of physicians, R or R, stands for recipe, i. e. take, • * * * RABBET, a deep groove or channel, cut in a piece of timber longitudinally, to receive, the edge of a plank, or the ends of a number of planks, which are to be securely fastened therein. The depth of this channel is equal to the thickness of the plank; so that when the end of the latter is let into the rabbet, it will be level with the outside of the piece. Thus the ends of the lower planks of a ship's bottom terminate upon the stem afore and the stern post abaft, with whose sides their surfaces are even. The surface of the garboard streak, whose edge is let into the keel, is in the same manner level with the side of the keel at the extremities of the vessel. RABBETING, in Carpentry, the planning or cutting of channels or grooves in boards. In ship carpentry, it signifies the letting-in of the planks of the ship into the keel; which in the rake and run of a ship, is hollowed away, that the planks may join the closer. RACE, a particularly strong tide or current. RACK, an engine of torture furnished with pulleys and cords, &c. for extorting confession from criminals. This instrument is happily banished from almost all christian coun- tries. - RACK, a frame of timber containing several sheaves, and usually fixed on the opposite sides of a ship's bowsprit, to direct the sailors to the respective ropes passing through it. RACKING a Tackle, the fastening two opposite parts together with a seizing, so as that any weighty body suspended thereby shall not fall down, although the tackle-fall should be loosened by accident or inattention. RADIAL CURves, are curves of the spiral kind, whose ordi- mates, if they may be so called, all terminate in the centre of the including circle, appearing like radii of that circle; whence the alſ) 6. RADIANT Poi Nt, or RAD IATING Point, is any point from which rays proceed. RADIATION, the act of a body emitting or diffusing rays of light all round, and from a centre. - RADICAL, that which is considered as constituting the dis- dinguishing part of an acid, by its union with the acidifying principle, or oxygen, which is common to all acids. Thus suſ- phur is the radical of the sulphuric and sulphureous acids. It is called the base of the acid; but base is a term of more extensive application. - RADICAL Sigm, (from radia, root,) in Algebra, is the character by which the root of a quantity is expressed, and is formed thus, V, while the particular root is indicated by a figure on the left of the sign : thus, & a, Ky a, Ky a, &c. denote the square root, cube root, and biquadratic root of the quantity a, or of any R A G other quantity placed under the like signs. When it is a com- pound quantity whose root is to be expressed, it is put in a parenthesis, and the sign prefixed ; thus, & (a” + l2,) means the cube root of the sum of a” plus bº; or it is otherwise indicated by a line thus, & a” + b%; the characteristic * is generally omitted in the Square root, so that instead of writing 3/ a for the square root of a, we merely write V a, by which the square root is always to be understood. RADII, the plural of RADI Us. . RADIOMETER, a name sometimes given to the Forp Staff. RADIUS, in Geometry, the semi-diameter of a circle, or a right line drawn from the centre to the circumference. It is implied in the definition of a circle, and it is apparent from its construction, that all the radii of the same circle are equal. The radius is sometimes called, in trigonometry, the sinus totus, or whole sine. The length of the radius of any circle is equal to that of an are of 67.2957795 degrees of the same circle. RADIX, the same as root, but used in a different sense by different authors; thus we say, radia of a system of logarithms, a system of notation, &c. mcaning the fundamental quantity on which the system is constructed, or by which all the others are compared. - RADIx of a System of Logarithms, is that number which involved to the power, denoted by ihe logarithm of a number, is equal to that number. This radix in the Common, or Brigg's Logarithms, is 10, and in the Naperian or Hyperbolic Logar- ithms, it is 2.71828,182, &c. and generally the radix in any system of logarithms, is that number whose logarithm in that system is unity. RADIX of a System of Notation, is that number which indicates the local value of the figures, and is in all systems represented by a unit and cipher (10), which is ten in the common system, two in the binary, three in the ternary, &c. RADIx, is also used as a term of comparison between any finite function and its expansion or development; thus we 1 sº know that F--- = 1 — 1 + r.” — r" -- 1:4 — &c. in which case 1 + r - l e g Tr' is sometimes called the radix of the series 1 — 1 + r"— 7-3 + 2* — &c. RAFT, a sort of float, formed by an assemblage of various planks or pieces of timber fastened together side by side, so as to be conveyed more commodiously to any short distance in a harbour or road than if they were separate. RAft Port, a square hole cut through the buttocks of some ships, immediately under the counter, to load or unload the planks and pieces of timber, which, on account of their great length, could not be got in or out otherwise. RAFTERS, in Building, are pieces of timber, which, standing by pairs on the raising piece, meet in an angle at the top, and form the roof of a building. RAGG, or Row LY, a genus of stones belonging to the siliceous class. It is of a dusky or dark gray colour, with many small 868 R. A. I R. A. I DICTIONARY OF MECHANICAL scIENCE. shining crystals, having a granular texture, and acquiring an ochry crust by exposure to the air. RAIA, the Ray, in Natural History, a genus of fishes of the order cartilaginei. These fishes are found only in the sea, where they feed on whatever animal substances they meet with. They are sometimes of the weight of two hundred pounds. They conceal themselves for the greater part of the winter in the mud or sand of the bottoms, and, indeed, are seldom seen near the surface of the water. The female is larger than the male, and produces her offspring living, and only one at a time; the young extricating itself gradually from its confinement, and remaining some time attached by the umbilical vessels, after its complete appearance. There are nineteen species; the skate is one of the largest of the genus, weighing sometimes two hun- dred pounds, and one of the size is reported to have been served up at St. John’s College, Cambridge; it is the most esteemed species of the genus. The thorn-back is much inferior to the skate in size and goodness. It is distinguished by its long and curved spines, on its upper surface. The above are rhomboidal. The sting- ray inhabits the Indian and Mediterranean seas, and its tail is armed with a very long serrated spine, with which it can inflict very formidable wounds, and which it casts off every year. This was formerly supposed to contain the most subtle poison. It injures, however, only by piercing and laceration; and to pre- vent this, the tail is almost always cut off as soon as the fish is caught. The torpedo inhabits the Mediterranean and the North seas, and grows to the weight of twenty pounds. This fish possesses a strong electrical power, and is capable of giving a very considerable shock through a number of persons forming a communication with it. This power was known to the ancients, but exaggerated by them with all the fables natural to ignorance, and it is only recently that the power was ascertained to be truly electric. It is conducted by the same substances as elec- tricity, and intercepted by the same. In a minute and a half no fewer than fifty shocks have been received from this animal, when insulated. The shocks delivered by it in air are nearly four times as strong as those received from it in water. This power appears to be always voluntarily exercised by the tor- pedo, which occasionally may be touched and handled without its causing the slightest agitation. When the fish is irritated, however, this quality is excercised with proportional effect to the degree of irritation, and its exercise is stated in every instance to be accompanied by a depression of the eyes. RAIL, or WATER RAIL, in Ornithology, the name of a bird of a long slender body, with short concave wings. The legs of this bird are placed very far behind, and are of a dusky flesh colour. Its toes are very long, and though the feet are not webbed, it takes the water, swims with ease, and is often observed to run apparently along its surface. It delights less in flying than in running, which it does very swiftly along the margins of brooks covered with rushes. In running, it occa- sionally flirts up its tail; and in flying, its legs hang down. Pen- nant says, that it is an unique species. RAIL Land, in Ornithology, is a migrating bird. It has a short, strong thick bill, and is generally found among corn, grass, broom, or furze. It leaves this kingdom before winter. It abounds in Anglesea, where it appears about the middle of April, and is supposed to come from Ireland. Of the Hebrides and Orkneys it is generally an inhabitant. RAILING, in Rural Economy, is a sort of fence constructed with posts and rails. It is frequently used to protect young hedge fences and trees from the depredations of cattle or other animals. RAILLERY, Dr. Johnson has defined to be a slight satire or satirical merriment; and another writer has compared it to a light that dazzles, but does not burn. It is serious, severe, and good-humoured, and if it perplexes it should never offend. RAILWAY, Tram or Dram Road, in Rural Economy, is a track constructed of wood, stone, or other materials, but chiefly of iron, upon the level surface of an inclined plane, or in other situations, for the purpose of diminishing friction, and for the plore easy conveyance of heavy loads of any kind of articles. Until very lately, rail roads were chiefly confined to mines of various descriptions, but they are now coming into more gene- ral use, and are capable of being applied with advantage to many roads on which they have never yet made their appear- ance. In Derbyshire, Shropshire, Lancashire, and several other counties, they are very numerous, some of them cxtend- ing several miles. At first timbers were laid down, on which flat bars of iron were nailed. This was afterwards succeeded by cast iron of sufficient thickness, and the timber was dis- missed. The benefits arising from these rail roads have given rise to numerous calculations. Dr. Anderson estimates, that upon a perfect level, one horse of moderate strength can draw with ease from twelve to twenty tons. On inclined planes, where the ends of canals cannot be brought to join the sea. without many locks, they might be employed with the greatest success. Instead of loading any pair of wheels with an enormous weight which would tend to crush the road over which they pass, it has been found by experience more bene- ficial to employ a string of carriages, that the pressure may be distributed. Near Colebrook Dale there is a rail road, on which loaded boats are drawn up to a canal two hundred and twenty feet above the level of the Severn, and let down into it in a similar manner, by which means twenty-two locks are saved, and the work is executed in a more expeditious man- ner. This is supposed to be the greatest inclined plane in Europe, or perhaps in the world; for though they are much used in China in the place of locks, none of them are equal in height and acclivity to this. - RAIN. This phenomenon some philosophers have attributed entirely to the influence of the electric fluid, and this explana- tion has been rendered the more probable by the circumstance of most abundant showers usually accompanying a thunder storm. It is worthy observation, that much the greatest quan- tity of rain falls in that time of the year when the air appears clearest, and when, from the heat, the appearance of moisture on the ground soon disappears; also, that in warmer countries than ours, and where the air appears much clearer, the quan- tity of rain which falls greatly exceeds that in this country. Very frequently rain is produced by the concussion or conden- sation of two clouds, the one positively and the other negatively electrified ; and this has been proved by experiment with a kite elevated to a great height in the air. There is no necessity to maintain that rain gan never be produced in any other manner. The mean annual quantity of rain is greatest at the equator, and decreases gradually as we approach the poles. Thus, at Grenada, West Indies, it is 126 inches; Cape Francois, 120 : Calcutta, 81 ; Rome, 39; England, 35; Petersburgh, 16. The number of rainy days is smallest at the equator, and increases in proportion to the distance from it. The mean num- ber from north latitude 12° to 439, being 78; from 43° to 460, being 103; from 46° to 50°, being 134; from 51° to 60°, 161. The number of rainy days is often more in winter than in summer; but the quantity of rain is greater in summer than in winter. According to an observation made in England, if two vessels of equal extent be exposed at different heights, and the quan- tity of water which falls into them during any considerable time, for instance, a year, be measured, it is found that the vessel at the greater height receives less water. This seems to point out that the drops of rain become larger as they fall, by the precipi- tation of the watery vapours which they encounter; and that in lowering the temperature of the space which they traverse, they cause these vapours to precipitate more abundantly. This experiment, repeated at the observatory at Paris, gave the same result. A necessary consequence is, that, in general, more rain falls in the valleys than on the hills. The quantity of rain which has fallen in diſſerent places has been accurately observed, and from which it appears, that much depends upon local situation. The quantity of rain which fell at Paris in the course of a year, taken at a medium of six years, was 20:19 inches; and in London, the medium quantity per annum, for the same number of years, was 23-001. Much, however, depends upon the height of the rain-gage from the surface of the earth, more than upon the comparative alti- tudes of it with reference to the surface of the sea, or any fixed point; the rain-gage on the top of a mountain, giving nearly as much as that in the plain beneath ; whereas, one gage placed on the top of a house or church, and another below, give very different quantities. The following table exhibits the results of several very accurate observations made on three gages, one at the bottom of a house, another at the top of the R. A. I R. A. I DICTIONARY OF MECHANICAL SCIENCE. 869 same, and a third on Westminster Abbey, the greatest care being taken that none of the water should evaporate after it entered the gage, by passing it through a narrow tube into a bottle well stopped below. - From these results it will appear, that there fell below the top of a house above a fifth part more rain than what fell in the same space above the top of the same house. And that there fell upon Westminster Abbey not much above half what Was found to fall in the same space-below the tops of the houses. This experiment has been repeated in other places with the same result; and, notwithstanding the cause of this extraor- dinary difference has not yet been discovered, it is at the same time useful to be apprised of it, to prevent any inaceurate Con- clusions from a comparison of different gages. The Quantity of Rain which fell in London from July 7, to July 6 in the succeeding Year. L Middle G Upper ower | Middle Gage, Gage on MONTHS. Gage of a Top of a Westminster House. House. Abbey. - - Inches. Inches. Inches. From July 7th to the 31st. 3:591 3:210 2°311 August,. . . . . . • * * * * * - - - - - 0°558 0.479 ) 0'508 September, . . . . . . . . . tº a º 0°421 0'344 § J. October, . . . . . . . . . . . . . . . º 2°347 2°061 1°416 November, . . . . . . . . . . © & 1,079 O'842 0-632 |December,. . . . . . . . . . . . . . 1:612 1.258 O'994 January, . . . . . . . . . . . . g º a 2:07.1 l'455 1'035 February, . . . . . . . . . . . . . . 2'861 2'494 I '335 |March, . . . . . . . . . . . . . . . . I '807 1:303 O'587 April, . . . . . . tº e º ſº e º E tº tº ſº º º 1°437 I '213 0'994 May, . . . . . . . . . . . . & e s tº 2'432 || 1 '745 1° 142 June,. . . . . . . . . . . . . . . . . . 1°997 1426 & 1°145 July 7. . . . . . . . . . . . . . . . . . 0°395 0.309 $ 22'608 18 139 12'099 l The following Table exhibits similar Experiments, made on two Gages, one on the Top of Mount Rennig, in Wales, and another in the Plain 1350 feet below the other. Bottom of the Top of the Mountain. Mountain. Inches. Inches. From July 6 to 16, . . . . . . . . O'709. 0°648 July 16 to 29, . . . . . . . . 2' 185 2' 124 July 29 to Aug. 10, .... 0-610 0.656 Sept. 9, both bottles had run Over. - From Sept. 9 to 30, . . . . . . . . . 3°234 2°464 Oct. 17, bottles run over. - From Oct. 17 to 22,... . . . . . . . . 0-747 O'885 Oct. 22 to 29, . . . . . . . . . . . . . . . 1.281 1°388 8.766 8'165 l These experiments justify the assertion made above, viz. that the quantity of rain, in any place, depends, principally upon its altitude above the surface of the earth, and not much upon the comparative altitude of two places with regard to the surface of the sea, and consequently not upon the rarity or den- sity of the atmosphere, as was for a long time supposed by phi- losophers. - RAINBOW. The rainbow is a circular image of the sun variously coloured. It is thus produced ; the solar rays, enter- ing the drops of falling rain, are refracted to their farther sur- faces, and thence by one or more reflections transmitted to the eye. At their emergence from the drop, as well as at their entrance, they suffer a refraction, by which the rays are sepa- rated into their different colours, and thus, therefore, are exhi- bited to an eye properly placed to receive them, That this is the true account of the formation of the rainbow, appears from the following considerations. 1. That a bow is never seem but when rain is falling, and the sun shining at the same time, and that the sun and bow are always in opposite quarters of the heavens; this every one’s experience can testify. 2. That the same appearance can be artificially represented by means of water thrown into the air, when the spectator is placed in a pro- per position with his back turned to the sun : - Let A B be a drop of water, and CD a pencil of solar rays 9 s A T} Ş----, incident thereon; if all the rays - ‘sy.......... ... of any one colour, as red, be- >g::::::::::::::::::::::::... longing to the pencil C D, be *:::::::/* *... I refracted to the same point G, ~:S IB and thence reflected, they will fall on the space R. Q, with the same obliquity and at the same distances from each other, as the refracted rays, if proceeding backward from G, would fall on the space T S ; but these at their refraction would emerge into T D, CS, &c. parallel to each other, and therefore will enter an eye properly placed copiously enough to cause a sen- sation ; a red colour will therefore appear in the direction of these rays, and so of others. But if the refracted rays do not meet in the same point, the reſlected rays will not fall on the - surface, at the same distance from each other, as PT and IS do, though their ob- liquity to the surface be equal to that of the latter: therefore the refracted rays will emerge, diverging from each other, and consequently will not enter the eye copiously enough to cause a perception of their colour. It is plain that where the rays of any colour emerge parallel, all these emerging rays will be inclined to the incident rays in the same angle. And by calculation it is found, that the red rays when they emerge parallel to each other, make with the inci- B O 2 y ºs SS dent rays an angle, O the violet an angle, C R. s A CO, of 40° 17', and Yr ** -- a-N- the rays of the other X. A- colours angles greater than the latter, and less than the former. If through the eye which receives the emerging rays, there be drawn a line A X, parallel to the inci- dent rays, it will make with the emerging rays of each colour, angles R. Ax, and V A X, &c. equal to the above. This line A X is called the axis of vision. The several drops placed in the lines A R, A V, &c. will exhibit to the eye at A, the several prismatic colours respectively, as appears from what has been said ; and if those lines be supposed to revolve with a conical motion round the axis of vision, it is evident for the Same rea- son, that all the drops placed in each of the conic surfaces so generated, will transmit the rays of each colour respectively to the eye, and therefore that a number of circular concentrie arches of the prismatic colours adjoining to each other, will be exhibited to the eye. This explanation relates to the interior bow, whose colours beginning from the outside, are red, orange, &c. as in the prismatic spectrum, which bow can never be seen 2" if the sun be elevated more than 42° 2' above the horizon; for the 4. horizon HO always makes with the #º º H axis of vision, A X, an angle equal to the elevation of the sun ; there- fore in the case here stated, the line A Q, marking the vertex of a rainbow, would fall entirely below the horizon. As the interior bow is formed by one reflection and two refractions, so the exterior bow is formed by two reflections and two refractions, at the surfaces of the drops of falling rain. If the red ray of any 10 M 870 R. ''A. I R A M DICTIONARY OF MECHANICAL SCIENCE. pencil, CD,0f solar rays, after refrac- x I, tion, intersect each other at R, so o that when reflected at TV, they may proceed parallel within the drop, after a 2d reflection at XQ, they will pro- ceed to LM, intersecting each other "º at S, equally distant from XQ, as R. is from TV, and as the rays QT, XV, if they proceeded back- ward, would after reflection so fall on the surface, NO, as to be refracted into air parallel to each other ; so X M, Q L, fall- ing on the surface precisely in the same circumstance, shall be refracted to the eye parallel to each other, and therefore will enter it copiously enough to cause a perception of their colour, (and so of the rest). The red rays, when 2merging parallel after two reflections, are by calculation found to make with the inci- dent rays, and therefore with the axis of vision, an angle of 50° 57". The violet rays, when emerging parallel, are found to make with their incident rays, and therefore with the axis of vision, an angle of 54° 7' : the other emerging rays meet the axis of vision in the intermediate angles. And hence it is easy to ex- plain the generation of the exterior bow in the same manner as that of the interior. It is to be remarked, that the order of colours in the exterior bow is the reverse of that in the interior, and the reason of this appears in the above explanation. For A E, 3d figure above, which marks the direction of the violet rays in the outer bow, contains with A X, the axis of vision, a greater angle than AD, (which marks the direction of the red rays,) contains with the same axis. And the reverse is the case in the interior bow. It is evident, (for a reason similar to that given in the case of the interior bow) that an exterior bow can- not be seen when the elevation of the sun is above 54° 7'. Lunar RAINBow. An iris formed by the refraction of the moon's rays, in drops of rain, in the night-time. Marine RAINBow, the Sea Bow, is a phenomenon sometimes observed in a much agitated sea, when winds, sweeping part of the tops of the waves, carry them aloft, so that the rays of the sun are refracted, &c. as in a common shower. - RAINGAGE, or PLU vioMeter, a machine for measuring the quantity of rain that falls. There are various kinds of rain- gages; that used at the apartments belonging to the Royal Society at Somerset-house, is thus described :-The vessel that receives the rain is of a conical form, strengthened at the top by a brass ring twelve inches in diameter. The sides of the funnel and inner lip of the brass ring are inclined to the hori- zon in an angle of more than 65°, and the outer lip in an angle of more than 50°, which are such degrees of steepness, that there seems no probability either that any rain which falls within the funnel, or on the inner lip of the ring, shall dash out, or that which falls on the outer lip shall dash into the funnel. The annexed figure represents a raingage of the best construction. It consists of a hollow cylinder, having within it a cork ball attached to a wooden stem, which passes through a small opening at the top, on which is placed a large funnel. When this instrument is placed in the open air in a free place, the rain that falls within the circumference of the funnel will run down into a tube, and cause the cork to float; and the quantity of water in the tube may be seen by the height to which the stem of the float is raised. The stem of the float is so graduated as to shew, by its divisions, the number of perpendicular inches of water which fell on the surface of the earth since the last observation. It is hardly necessary to observe, that after every observation the cylinder must be emptied. A very simple raingage, and one which answers all practical purposes, consists of a copper funnel, the area of whose open- ing is exactly ten square inches; this funnel is fixed in a bottle, and the quantity of rain caught is ascertained by multiplying the weight in ounces by 173, which gives the depth in inches and parts of an inch. In fixing these gages, care must be taken that the rain may have free access to them ; hence, the tops of buildings are usually the best places. When quantities of rain collected in them at different places are compared, the instru- ments ought to be fixed at the same heights above the ground . at both places, because, at different heights, the quantities are always different, even at the same place. Sec RAiN. RAISING a Purchase, the act of disposing certain instruments or machines, in such a manner as that, by their mutual effects, they may produce a mechanical force sufficient to overcome the weight or resistance of the object to which this machinery is applied. - - RAISINS, grapes prepared by suffering them to remain on the vine till they are perfectly ripe, and then drying them in the sun, or by the heat of an oven. The difference between raisins dried in the sun, and those dried in ovens, is very obvi- ous : the former are sweet and pleasant; but the latter have a latent acidity with the sweetness, that renders them much less agreeable. - - RAIT, in Rural Economy, a term used to signify, the pro- cess or operation of dissipating the sap of vegetables by expo- sure to moisture, or the influence of the atmosphere. It is sometimes applied to hay when it has been much exposed to the alternations of wet and dry weather, but more particularly to hemp and flax. The process of raiting requires much nicety, its design being to detach the covering or bark of hemp and flax from the stalk, by spreading the plants thinly upon close grassy surfaces, or putting them into water during a given time for the same purpose. - * RAKE, in Agriculture, a tool of the tooth kind, made use of for many purposes of husbandry, as for collecting together hay, corn, stubble, roots, leaves, and other similar materials. Of this implement there are many descriptions. - - RAKE, the projection of the upper parts of a ship at the height of the stem and stern, beyond the extremities of the keel; thus, if a plummet is hung from the top of a ship’s stern, so as to be level with the continuation of the keel, the distance between the after-end of the keel and the plummet will be the length of the rake of the stern. - - RAKE, is also applied to the masts when they are out of a perpendicular situation, as, that ship's mainmast rakes aft. RAKING, the act of cannonading a ship on the stern or head, so as that the balls shall range the whole length of the decks, which is one of the most dangerous incidents that can happen in a naval action; this is frequently called raking fore and aft, and is similar to what is termed by engineers enfilading. RAKE, or Vein, in Geology, is the most common repository of metallic ores. These veins intersect mountains sometimes nearly in a vertical manner, but more generally with a greater or less degree of inclination from a perpendicular. RALLYING, in War, re-assembling or calling together troops broken and put to flight. . RAM, in Hydraulics, is a machine for raising water to any given height, by means of the momentum of a stream of water flowing through a pipe. The passage of the pipe being stopped by a valve, which is raised by the stream as soon as its motion becomes sufficiently rapid, the whole column of water concen- trates on the valve, and acts as a single solid, so that it must resist any pressure. Now if the valve open into a pipe leading to an air vessel, a certain quantity of water will be forced into it, so as to condense the air more or less rapidly, to the degree that may be required for raising a portion of the water con- tained in it to any given height. , * RAM, in Mythology, the name of the highest god among the Gentoos. - RAM, Battering, in Artillery, is a military engine with an iron head, resembling that of a ram, much used by the ancients to batter and break down the walls of places besieged ; but since the invention of cannon, this once formidable instrument has been dismissed from service. Battering rams were of three kinds; the first rude and plain, the others artificial and com- pound. The first appears to have been nothing more than a huge beam headed with iron, with which men by mere muscular force assailed a wall, and yet produced but little effect. Jose- phus describes a second sort of battering ran, as resembling the mast of a ship suspended horizontally in the middle by ropes fastened to another beam above, which is fixed on posts for its support. Thus balanced, it is swung by a number of men, in proportion to its weight, with its head violently against the wall, from which it recoils, and becomes prepared for another stroke. Scarcely any building could resist the tremendous blows of this machine. The third sort differed from the second only by having covering for the soldiers, to guard them against mis- R A M R. A. N. 871 DICTIONARY OF MECHANICAL SCIENCE. siles thrown from the walls. Some of these destructive instru- ments were suspended in a frame mounted on wheels for their more easy conveyance from place to place ; and we are informed by Plutarch and Vitruvius, that they varied in length from 80 to upwards of one hundred feet; and while from the effects the largest have been known to produce, modern calculators have estimated their weight at more that three hundred tons. So late as the fourteenth century the ram was much in use. It was employed by Sir Christopher Wren in demolishing the walls of the old church of St Paul’s, in order to his erecting the present structure, and , was found to be an excellent machine for the completion of his purpose. See BATTERING Ram. RAMA, in Hindoo Mythology, the name of a celebrated mor- tal, in whom their deity Vishnoo was incarnated for the purpose of relieving mankind from the oppression of Ravena, the malig- mant king of Lanka or Ceylon. - - RAMAD AN, a sort of lent observed among the Mahometans with great rigour, during which they fast the whole day from the first appearance of a new moon until the next new moon ap- pears. To make amends for this abstinence, their nights are spent in riot and dissipation. RAMAYANA, the title of a poem in Sanscrit, of great cele- brity in India, regarded as Sacred by some sects, and greatly venerated by all.: . RAMI, in Hindoo Mythology, one of the many names of the goddess Parvati. . RAMMER, is a cylindrical block of wood nearly fitting the bore of a cannon, and fastened on a wooden staff, or on a stiff rope well served with spun yarn. It is used to drive the charge of a cannon home, or to the innermost part of it. The rope- rammers are most general in ships of war. RAMPART, in Fortification, a massy bank or elevation of earth raised above the body of a place, to shelter those within from the direct fire of the enemy. RAM PHASTOS, the Toucan, &c. a genus belonging to the order of picae. The bill is very large, and serrated outwardly. The nostrils are situated behind the base of the beak; and in most of the species the feet are toed, and placed two forwards and two backwards. The tongue is long, narrow, and feathered on the edges. Mr. Latham enumerates 15 different species. RAM PHOID, a particular point of retrogression. RAMSDEN'S MACHINE for dividing Mathematical Instru- ments, is a useful invention, by which these divisions can be performed with exceedingly great accuracy, such as would formerly have been deemed incredible. On discovering the method of constructing this machine, its inventor, Mr. Jesse Ramsden, received £615 from the commissioners of longitude; engaging himself to instruct a certain number of persons, not exceeding ten, in the method of making and using this machine from the 28th of October, 1775, to 28th of October, 1777; also binding himself to divide all octants and sextants by the same engine, at the rate of three shillings for each octant, and six shilings for each brass sextant, with Nonius's divisions to half- minutes, for as long time as the commissioners should think proper to let the engine remain in his possession. Of this sum of £615 paid to Mr. Ramsden, £300 were given him as a reward for the improvement made by him in discovering the engine, and the remaining £315, for his giving up the property of it to the commissioners. - - This engine consists of a large wheel of bell metal, supported on a mahogany stand, having three legs, which are strongly connected together by braces, so as to make it perfectly steady. On each leg of the stand is placed a conical friction-pulley, whereon the dividing wheel rests : to prevent the wheel from sliding off the friction pulleys, the bell metal centre under it turns in a socket on the top of the stand. ' The circumference of the wheel is ratched or cut into 2160 teeth, in which an end- less screw acts. Six revolutions of the screw will move the wheel a space equal to one degree. Now, a circle of brass being fixed on the screw arbor, having its circumference divided into 60 parts, each division will, consequently, answer to a motion of the wheel of 10 seconds, six of them will be equal to a minute, &c. Several different arbors of tempered steel are truly ground into the socket in the centre of the wheel. The upper parts of the arbors that stand upon the plane are turned of various sizes, to suit the centres of different pieces of work to be divided. When any instrument is to be divided, the centre of it is very exactly fitted on one of these arbors; and the instrument is fixed down to the plane of the dividing wheel, by means of screws, which fit into the holes made in the radii of the wheel for that purpose. The instrument being thus fitted on the plane of the wheel, the frame which carries the dividing point is connected at one end by finger screws, with the frame which carries the endless screw ; while the other end embraces that part of the steel arbor which stands above the instrument to be divided, by an angular notch, in a piece of hardened steel; by this means both ends of the frame are kept perfectly steady, and free from any shake. The frame carrying the dividing point or tracer, is made to slide on the frame which carries the endless screw to any distance from the centre of the wheel, as the radius of the instrument to be divided may require, and may be there fastened by tightening two clumps; and the divid- ing point or tracer being connected with the clumps by the double-jointed frame, admits a free and easy motion towards, or from, the centre for cutting the divisions, without any lateral shake. From what has been said, it appears, that an instru- ment thus fitted on the dividing wheel, may be moved to any angle by the screw and divided circle on its arbor, and that this angle may be marked on the limb of the instrument with the greatest exactness by the dividing point or tracer, which can only move in a direct line tending to the centre, and is altoge- ther freed from those inconveniences that attend cutting by means of a straight edge. This method of drawing lines will also prevent any error that might arise from an expansion or contraction of the metal during the time of dividing. RAMUS, PETER, a celebrated French mathematician and philosopher, was born in 1515, and fell a sacrifice to his reli- gious opinion, on the massacre of St. Bartholomew's day, 1572, in his 57th year. He was author of several works relating to mathematical subjects. A RAN, twenty cords of twine wound on a reel, every cord so parted by a knot as to be easily separated. RANA, the Frog, in Natural History, a genus of Amphibia of the order of Reptiles. There are thirty-six species, of which the following deserve the chief attention :-The common toad, is found in shady and damp situations throughout Europe, and often is met with in cellars. In spring it moves towards the water, and lays its ova in a brilliant band of glutinous sub- stance, several feet in length. The ova appear like beads of jet, and in fourteen days these convolved larvae are developed and swim about, nourishing themselves by insects and vege- table substances, till their tail disappears, and their legs are formed, and they pass from water to land. The toad is always covered with tubercles, is generally of a dark brown colour above, and a light yellow on the lower parts both of the body and limbs. It lives to a considerable age, surviving in many instances even twenty years; and the case of a toad, which arrived at the age of forty, is mentioned by Mr. Pennant. The ideas formerly entertained of venomous qualities possessed by this animal, are now ascertained to be well founded, as Sir H. Davy has found, on dissection and analysis, venomous matter contained in follicles in the cutis vera, round the head, and even on the extremities.—Statements have often been published of toads found living in large blocks of wood and of stone, with no perceivable inlet for the air, and touched on all sides by the substance in which they were enclosed. It is ascertained that a toad will live for many weeks, and even months, in a very small case, or under a pan, buried deeply in the earth. The eyes of the toad are remarkable for their clearness and beauty, and excite sensations of a very different nature from that disgust, and even horror, which its general appearance almost universally excites. The Surinam toad, much larger than the common toad, being sometimes seven inches in length, is almost equally loathsome with the last, and is distinguished particularly by that curious deviation from the general course of nature, the exclusion of its young from its back, which con- tains a variety of cells for their residence, and a certain degree of maturation. The common frog, is met with almost every where throughout Europe, in low and wet situations, where it can procure that food on which it principally subsists, worms and insects. The green frog, is much larger than the last spe- cies, and abounds in many countries in Europe, though but 872 R. A. N. R A P : DICTIONARY OF MECHANICAL SCIENCE. rarely to be found in England. They are in some places much used for food, particularly in France, and thought fittest for the table in the month of June. The bull-frog, is found in many regions of North America, and grows to the length of eighteen inches from the nose to the hind feet. Its sounds resemble the lowing of a bull. They are highly rapacious, often commit great depredations on the poultry, swallowing even young geese without considerable difficulty. The tree frog, is not found in Great Britain, but is met with in various other parts of Europe, and in elegance and activity is superior to every other Euro- pean species. In summer it resides in the woods, and haunts the trees in quest of insects, which it approaches on its belly, in the same manner as a cat to a mouse, and at length seizes with an elastic and instantaneous spring. It is particularly noisy on the approach of rain. In winter it takes up its abode in the bottom of the waters, remaining till the spring in a state of torpor. - RANCIDITY, in Chemistery. Fixed oils are liable, by keeping, to undergo a change well known by the name of ran- cidity. They become thick, acquire a brown colour, an acrid taste, and a disagreeable smell. The oil thus altered converts vegetable blues into red, and of course contains acid. - RANDOM Shot, in Gunnery, is a shot made when the muzzle of a gun is raised above the horizontal line, and is not designed to shoot directly or point-blank. The utmost random of any piece is about ten times as far as the bullet will go point-blank. RANELAGH Rotunda and Gardens, near Chelsea, built and opened for musical performances in 1742. Degenerating into a scene of licentiousness, it was shut up in 1803, since which the buildings have been wholly demolished. RANGE, in Gunnery, the path of a bullet, or the line it describes from the mouth of the piece to the point where it lodges. -- RANGE, a sufficient length of the cable drawn upon the deck before the anchor is let go, that, by its sinking to the bot- tom without being interrupted, the flukes may be forced deeper into the ground; therefore the range drawn up out of the tier ought to be equal in length to the depth of the water where the ship anchors. - RANGE, is also the distance to which a bomb or cannon ball is thrown from a piece of artillery by the explosion of gunpow- der. The flight of a shot is distinguished by artillery men into two different ranges, of which the first is called the point-blank, and the second the random shot; to these also may be added the ricochet, or rolling and bounding shot. The point-blank range is the extent of the apparent right line described by a ball discharged from a cannon. The random shot is, when, by letting the breach down upon the bed of the carriage, the ball is carried to its greatest possible distance, and describes a curve in its ſlight. The ricochet is fired by elevating the piece from three to six degrees, and only charging it with a quantity of powder sufficient to carry the shot along the face of the works attacked; the shot, thus discharged, so as to go just over the parapet, rolls, and bounds about, killing, maiming, or destroying all it meets in its course, creating much more disorder by going thus slowly, than if thrown from the piece with greater violence. As one of the effects of the bomb results from its weight, the range of mortars is extremely different from that of cannon, because the former is not pointed at a cer- tain object like the latter, but inclined to the horizon at a cer- tain angle, so that the bomb being thrown up obliquely, may fall upon the place intended ; hence it appears, that the mortar has no point-blank range, or at least that no use is made of it. To make a bomb fall on a given place, two things are to be considered, viz. the elevation of the mortar, and the quantity of powder used to charge it: respecting the former, a bomb will be thrown to the greatest distance when the elevation of the mortar is 45 degrees, it being the half of 90 degrees, or a right angle, that is equally distant from the horizon and the zenith; hence it follows, that if a mortar is elevated any number of degrees above 45, it will throw the shell to the same distance as if depressed an equal number of degrees below 45: where weight is required, as for the destruction of any building, the mortar should be elevated as much as possible for the distance, but when the business is to fire on a body of men, it must be pointed as much below 45, that the bomb may not have force to penetrate far into the ground, and the splinters in the explosion. may do more execution. Ricochet signifies duck and drake, a name given to the bounding of a flat stone thrown almost hori-. zontally into the water. l - It was the opinion of engineers formerly, that by charging. the pieces high, the ball was thrown to a greater distance. Hence the pieces were charged with two-thirds, or even the whole weight of the shot, in order to impel it with greater velo- city ; but it has been discovered since, that the half or one- third of the weight of the ball is the fittest charge for the piece. It may not be amiss to observe here, that the range of cannon, is greater in the morning and at night, than at noon; and in cold, than in hot weather. The reason is, that at these times the air being less heated, gives less way to the dilatation of the powder, which being, by these means, confined as it were to a smaller sphere of action, must have a stronger effect in propor- tion, When the lengths of cannon are proportionable to the height of the charge, the shot will be discharged with the same velocity, whatever the calibre may be. The greatest distance to which a shell can be thrown, with the strongest charge, is little more than about 1800 or 2000 fathoms. See GUNNERY. To RANGE, is to sail in a parallel direction, and near to, as, “we ranged the coast;” “the enemy came ranging up along side of us.” - - RANGER, a sworn officer of a forest, appointed by the king's letters patent, whose business is to walk through his charge, to drive back the deer out of the purlieus, &c. and to present all trespasses within his jurisdiction at the next forest COUlrt. RANGES, in a ship, two pieces of timber that go across from side to side : the one on the forecastle, a little abaft the foremast; and the other in the beakhead, before the wouldings. of the bowsprit. # RANK, in War, is a row of solders placed side by side. RANK, the order or place assigned a person suitable to his. . quality or merit. - - • RANSOM, a sum of money paid for the redemption of a per- son out of slavery, or for the liberty of a prisoner of war. - RANT, an extraordinary flight of passion, overshooting nature and probability. It—is sometimes introduced into the drama, and occasionally into the pulpit. RANUNCULUS, a genus of the polyandria class, and poly- ginia order; in the natural method ranking in the 26th order, multisiliquae. A well-known garden flower, of which there are many species. The Persian Crowfoot, or Garden Ranunculus, is the most noted. - RAPE, in Law, is where a man has carnal knowledge of a woman by force, and against her will ; by 18 Eliz. c. 7, if any person shall unlawfully and carnally know and abuse any woman-child under the age of ten years, whether with her con- sent or against it, he shall be punished as for a rape. And it is not a sufficient excuse in the ravisher, to prove that she is a common strumpet; for she is still under the protection of the law, and may not be forced. Nor is the offence of a rape mitigated by shewing that the woman at last yielded to the violence, if such her consent was forced by fear of death or duress; nor is it any excuse that she consented after the fact. 1 Haw. 108. ** - - RAP e, is also a name given to a division of a county, and sometimes means the same as a hundred, and at other times. signifies a division consisting of several hundreds. RAPE, in Gardening, the common name of a plant of the cabbage kind. RAPE, in Agriculture the name of a plant much cultivated for its seed, and also as a green food for cattle and sheep. RAPE Oil, an oil obtained by means of expression from the seeds of the above plant, in mills constructed for the purpose. The refuse is valuable as manure. RAPHANUS, Radish, a genus of the siliquosa order, in the tetradynamia class of plants; and in the natural method rank- ing under the 39th order, siliquosae. The calyx is close : the siliqua torose, or swelling out in knots, sub-articulated, and round. There are two melliferous glandules between the shorter stamina and the pistil, and two between the longer stamina and the calyx. There are six species. R A P. R. A. T DICTIONARY OF MECHANICAL SCIENCE. 873 * RAPIDS, Boat for passing up. The American papers con- tain some remarkable accounts of a newly invented boat, which has been brought into operation on the rapids of the Delaware, which ascends against the stream, and tows up ordinary boats, heavily laden, with it. The plan scems to be this :—The anchor is dropped at the head of the rapid to be passed, to which is connected a rope, extending to the termination of the rapid; here a boat is provided, crossed by a shaft, to which is attached wheels with floats or paddles, of a width in propor- tion to the power required; on this shaft is a windlass, or drum, around which the rope is passed, and thence, over the stern of the boat, into the water; thus arranged, the boat is pushed into the rapid; and the current, acting with all its strength upon the floats, and they presenting to the stream a much greater surface and resistance or hold for the water than the prow of the boat, the wheels are turned by the current, which, winding up the rope, draws the boat irresistibly to the anchor at the head of the rapid. The boat has been found to ascend one-half faster than the current flows down, and to be capable of towing up whatever may offer itself. The boat, having thus performed its voyage, its appen- dages are disengaged, it is dropt down with the current, and is then ready again for another trip up the rapid. A corre- spondent of the New York Evening Post says:—“I had the pleasure a few weeks since, of witnessing the first experiment of the boat at that place, (opposite Trenton on the Delaware,) and was much surprised that an invention of such great utility had not before been put in operation. There can be no doubt as to the practicability of the plan, and the competency of the power to be acquired for propelling heavy laden boats against rapids; for in the experiment I witnessed, there was towed up at the same time, a large Durham boat, two batteawa, and twelve persons ! The Durham boat was old and leaky, and drew as much water as if loaded with three or four tons; and she ascended the rapids, (which run at about the rate of ten knots,) with as great rapidity apparently as when without any encum- brance. Many of our valuable rivers have not heretofore been navigated on account of obstructions in them by rapids, which have been insurmountable; but by the invention of Col. Clarke, such difficulties no longer exist. Much credit is certainly due to him for the invention, as it promises to be of the greatest utility to this country in the navigation of our rivers; and it is presumed that his plan will ere long be brought into general use throughout the United States.” RAPIER, formerly meant an old-fashioned cutting sword, but in the more modern sense it signifies a small sword, as contradistinguished from a cutting sword. RAPINE, in Law. To take a thing in private against the owner's will is theft; but to take it openly, or by violence, is rapine or robbery. RAPIRTRUM, in Botany, the wild turnip, so called from its affinity to Rapa, the cultivated one. It sometimes signifies a species of the sca cabbage. RAPTURE, an ecstasy or transport of mind. 89. RAPUNCULUS, in Botany, a root formerly much cultivated, but at present very little known. Its name is derived from the resemblance which the root bears to an oblong turnip. RARA AVIS, in Ornithology, the name of a bird common about the lakes and rivers of America. It is of the king- fisher kind, but nearly as large as a duck, black on the crown, but white on the breast and belly. RARE, in Physics, a relative term, the reverse of dense, being used to denote a considerable porosity, or vacuity be- tween the particles of a body; as the word dense implies a | 8 or 900 times rarer. contiguity or closeness of the particles. RAREFACTION, in Physics, is the making a body to ex- pand, or occupy more room or space, without the accession of new matter. It is by rarefaction that gunpowder takes effect; and to the same principle also we owe e6]ipiles, thermometers, &c. The degree to which air is rarefiable, exceeds all imagi- nation; perhaps, indeed, its degree of expansion is absolutely beyond all comprehensible limits. Upon the rarefaction of the air is founded the method of measuring altitudes by the baro- ter; in all cases of which, the rarity of the air is found to be inversely as the force that compresses it, or inversely as the weight of all the air above it at any place. The open air, in which we breathe, says Sir Isaac Newton, is 8 or 900 times lighter than water, and by consequence And since the air is compressed by the weight of the incumbent atmosphere, and the density of the air is proportionable to the compressing force, it follows, by computation, that at the height of about seven English miles from the earth, the air is four times rarer than at the surface of the earth; and at the height of 21, 28, or 35 miles, it is respec- tively 64,256, or 1024 times rarer, or thereabouts; and at the height of 70, or 140, and 210 miles, it is about 1,000,000,- 1,000,000,000,000, or 1,000,000,000,000,000,000, &c. Mr. Cotes has found, from experiments made with a thermo- meter, that linseed oil is rarefied in the proportion of 40 to 39 with the heat of the human body; in that of to 15 to 14, with that degree of heat wherein water is made to boil ; in the propor- tion of 15 to 13 in that degree of heat wherein melted tin begins to harden; and finally, in the proportion of 23 to 20, in that degree wherein melted tin arrives at a perfect solidity. The same author discovered, that the rarefaction of the air, in the same degree of heat, is ten times greater than that of Jinseed oil ; and the rarefaction of the oil about fifteen times greater than that of the spirit of wine. - - - RARITY, lightness, thinness, the reverse of density. RAT. See MUs. A Simple RAT Trap.—ſet a cask, ingeniously placed, be half filled with water, and let a false top, or lid, be nicely balanced about two inches below the edge of the mouth; in the middle of the lid let some wholesome meat be fastened, (as rats are very nice,) so that, the moment one of them sets foot upon the edge, it may be precipitated into the water below ; and, as the lid immediately resumes its position, the victim is secured, and a second, a third, or a fourth, may be successively secured and destroyed. t RATAFIA, a spirituous liquor, prepared from the kernels, &c. of several kinds of fruit, particularly of cherries and apri- cots. Ratafia of cherries is prepared by bruising the cherries, and putting them into a vessel wherein brandy has long been kept; then adding to them the kernels of cherries, with straw- berries, sugar, cinnamon, white pepper, nutmegs, cloves; and to twenty pounds of cherries, ten quarts of brandy. The ves- sel is left open ten or twelve days, and then stopped close for two months before it is tapped. Ratafia of apricots is pre- pared two ways, viz. either by boiling the apricots in white wine, adding to the liquor an equal quantity of brandy with sugar, cinnamon, mace, and the kernels of apricots; infusing the whole for eight or ten days, then straining the liquor, and putting it up for use : or else by infusing the apricots cut in pieces in brandy, for a day or two, passing it through a strain- ing bag, and then putting in the usual ingredients. RATCH, or RASH, in Clock-work, a sort of wheel having twelve fangs, which serves to lift up the detents every hour, and make the clock strike. RATCHETS, in a watch, are the small teeth at the bottom of the ſº or barrel, which stops it in winding up. t 874 R A T R. A. T. DICTIONARY OF MECHANICAL SCIENCE. RATE, the order or classes into which the ships of war are divided in the navy, according to their force and magnitude ; thus, the First Rate, comprehends all ships of one hundred guns and upwards, having 42 pounders on the lower deck, 24 ditto on the middle deck, 12 ditto on the upper deck, and 6 ditto on the quarter deck and forecastle. They are manned with 850 to 875 men, including their officers, seamen, marines, servants, &c.—N. B. In general the ships of every rate besides the cap- tain, have the master, the boatswain, the gunner, the chaplain, the purser, the surgeon, and the carpenter; all of whom except the chaplain have their mates or assistants, in which are com- prehended the sail-maker, the master at arms, the armourer, the captain's clerk, the gunsmith, &c. The number of other officers are always in proportion to the rate of the ship. A first rate has 6 lieutenants, 6 master's mates, 24 midshipmen, and 5 sur- geon's mates, who are considered as gentlemen ; besides the following petty officers, quarter-masters and their mates, 14; boatswain's-mates, and yeomen, 8; gunner's mates and assist- ants, 6 : quarter-gunners, 25; carpenter's-mates, 2, besides 14 assistants; 1 steward’s-mate to the purser, &c. Second Rate, includes all ships carrying from 90 to 98 guns upon three decks, of which those on the lower battery are 32 pounders; and those on the middle 18 ditto ; on the upper deck 12 ditto, and those on the quarter-deck 6 ditto; which usually mount to 4 and 6; their complement of men is from 700 to 750, in which are 6 lieutenants, 4 master’s-mates, 24 midshipmen, and 4 surgeon’s mates ; 14 quarter masters, and their mates, 8 boatswain's mates and yeomen; with 22 quarter gunners, 2 car- penter's-mates, with 10 assistants, and 1 steward, and 1 stew- ard's mate. Third Rate, consists of ships from 64 to 80 cannon, which are 32, 18, and 9 pounders. The 80 gun-ships, however, begin to grow out of repute, and give way to those of 74, 70, &c. which have only two whole batteries, whereas the former have three, with 28 guns planted on each, the cannon of their upper deck being the same as those on the quarter deck and forecastle of the latter, which are 9 pounders. The complement in a 74 is 650, and in a 64, 500 men; having in peace 4 lieutenants; but in war, 5; and when an admiral is aboard, 6. They have 3 master’s-mates, 16 midshipmen, 3 surgeon's-mates, 10 quarter- masters and their mates, 6 boatswain's mates and yeomen, 4 gunner's mates and yeomen, with 18 quarter gunners, 1 carpen- ter's mate, with 8 assistants, and 1 steward and steward's mate under the purser. - - - Fourth Rates, consist of ships from 50 to 60 guns upon two decks and the quarter-deck. The lower tier is composed of 24 pounders, and the upper tier of 12 ditto, and the quarter deck and forecastle 6 ditto. The complement of a 50-gun ship is 350 men in which there are 3 lieutenants, 2 master's-mates, 10 midshipmen, 2 surgeon's-mates, 6 quarter-masters and their Inates, 4 boatswain's thates and yeomen, 1 gunner, and 1 yeo- man, with 12 quarter-gunners, 1 capenter's mate, and 6 assist- ants, and a steward and steward’s mate. All vessels of war under the fourth rate are usually compre hended under the general names of frigates, and never appear in the line of battle. They are divided into two rates, viz. Fifth Rates, mounting from 32 to 40 or 44 guns. The latter have two decks of cannon, the lower battery being of 18 pound- ers, and that of the upper deck 6 ditto; but those of 36, or 32 guns, have only one complete deck of guns, mounting 12 pound- ers, besides the quarter-deck and forecastle, which carry 6 ditto. The complement of 44 guns is 280 men, and that of a frigate of 36 guns 240 men. The first has 3, and the second 2 lieutenants, and both have 2 master's mates, 6 midshipmen, 2 surgeon's mates, 6 quarter masters and their mates, 2 boatswain's-mates and 1 yeoman, 1 gunner's-mate and 1 yeoman, with 10 or 11 quarter gunners, and 1 purser's steward. Sirth Rates, consist of frigates from 20 to 30 guns, and carry 9 pounders; those of 28 guns having 3 pounders on their quar- ter deck, with 200 men for their complement; and those of 24, 160 men. The former has 2 lieutenants, the latter 1, and both have two master's-mates, 4 midshipmen, 1 surgeon’s-mate, 4 quarter masters and their mates, 1 boatswain's mate and 1 yeoman, 1 gunner's mate and 1 yeoman, with 6 or 7 quar- ter gunners, and 1 purser's-steward. The whole of these rates are termed post ships, v. e. their commander is a post captain, while those captains commanding vessels are de- nominated MAsters and CoMMANDERs ; which see. This last rate is generally said to comprehend all brigs, sloops of war, cutters, schooners, &c. carrying from 6 to 18 guns, but it is only true with respect to their pay, the rest of their estab- lisment of officers and crew varying according to their force and magnitude, many of them being commanded by lieutenants, and some, such as gun-boats, &c. by midshipmen, who have passed for lieutenants. The sloops of war carry from 8 to 18 cannon, the latter having 6 pounders, and the former (those from 8 to 10 guns) 4 pounders. Their officers are generally the same as in the sixth rates, with little variation, and their com- plement of men are from 120 to 60, in proportion to their force or magnitude.—N. B. Bomb-vessels are on the same estab- lishment as sloops; but fire-ships and hospital-ships are on that of fifth rates. - RATEEN, in Commerce, a thick woollen stuff, quilled, woven on a loom with four treadles, like serges, and other stuffs, that have the whale or quilling. RATIO, is the relation of two quantities of the same kind with respect to quantity, and is by some authors divided into arithmetical and geometrical ratio ; viz. arithmetical, when the term is used with respect to the difference of the two quanti- ties; and geometrical, when it relates to the number of times in which the one of those quantities is contained in the other; thus the ratio of 6 to 3 is : = 2. The leading term of the ra- tio being called the antecedent, and the latter the consequent; also the quotient or division of the former by the latter, is called the index or eaponent of the ratio. The equality of ratios con- stitute proportion. See PROPORTION. RAtio, is also distinguished by some authors, (principally of the old school,) into a variety of denominations, many of which are totally useless ; but which cannot, notwithstanding, be passed over in the present article. Irrational RATIO, is, when one of the terms of the ratio, at least, is an irrational quantity ; such is the ratio of V 3 to 1. Rational RATI o, is when there is no irrational quantity en- ters, or when the same irrational quantity enters into both terms, thus ~/ 6 to V 24 = x/6 to 2 N/6 = 1 to 2. RATIo of Equality, is when the terms expressing the ratio are equal, and therefore the exponent = I. RAtio of Greater Inequality, is when the antecedent exceeds the consequent; and ratio of less inequality, is when the latter exceeds the former. For several other distinctions, as Compound, Duplicate, Subdu- plicate, Triplicate, Subtriplicate, &c. see the several articles. Reduction of RATIOS, is the reducing them to less terms, the ratio of 36 to 24 – 6 to 4 = 3 to 2. Sometimes, however, when the terms of the ratio are very large it is difficult to reduce them in this manner, and then recourse must be had to the method of ſinding the greatest common measure or common divisor, which also fails if the two terms are prime to each other. In this case, though the exact ratio cannot be found in less terms, it is frequently desirable to find an approximate ratio expressed in less terms, and recourse must then be had to continued frac- tions, viz. convert the given ratio into a continued fraction, and thence find the series of converging fractions, each of which will be an approximate ratio of the proposed one, and so much the more accurate as it is farther advanced in the series. Let 1103 to 887 be a ratio, to which it is required to find an approximate ratio in less terms. 887) 1103 (1 216) 887 (4. 23)216 (9 9)23 (2 5) 9 (1 Hence by the rule in continued fractions, quoto. 1 4 9 2 1 1 4 1 5 46 97 143 240 l 103 app. ratios 1' 4° 37' 78' [I5' 193' 887 R. A. V R. A. Y. 875 DIC'ſ IONARY OF MECHANICAL SCIENCE. Each of which fractions approximates nearer to the true placed in the middle of a curtain; but now a detached work, ratio than any of those which precede it, and each nearer than any ratio that can be expressed in less terms. RATIOCINATION, the act of reasoning. RATION, in the Army, a portion of ammunition, bread, drink, and forage, distributed to each soldier in the army, for his daily subsistence, &c. The horse have rations of hay and oats when they cannot go out to forage. The rations of bread are regu- lated by weight. The ordinary ration of a foot soldier is a pound and a half of bread per day. The officers have several rations according to their quality and the number of attend- ants they are obliged to keep. When the ration is augmented on occasions of rejoicing, it is called a double ration. In the navy the rations of every man are a pound of bread and meat per day, a pint of chocolate for breakfast, half a pint of rum, which is mixed with water before it is served out; toge– ther with salt, vinegar, and vegetables. - RATIONABILES EXPENSAE, reasonable expenses, paid to members of parliament, and the proctors of the clergy in convocation, by the people, determined by the king, the prices of the necessary articles being taken into a due consideration. RATIONABILI PARTE BONORUM, a writ which lies for the wife against the executors of her husband, if they refuse her the third part of her effects, all debts being paid. RATIONAL FRActions, is the term commonly used to ex- press those fractions which may be decomposed into other fractions, the sum of which is equal to the given fraction; this cannot in all cases be effected, but where it can, such fractions are called rational fractions. In simple numerical fractions, the decomposition, when it can be effected, is drawn from the indeterminate analysis. Thus, let it be proposed to resolve Since 35 = 7-5, let 5a. --7 y . 19 . e the fraction 35 into two other fractions. tº - Q: 7 g © the two required fractions be 7 and % ; then their sum 19 tº * & & & F 353 whence 5 a -- 7 y = 19, which is an indeterminate equa- tion of the first degree, and the solution of it gives a = 1 and 19 1 2 — O . º – *T* -- •=e e y = 2; therefore 35 T 7+ 5 If the denominator is a prime number, the decomposition is impossible, as it is also in some other cases; but if a. and y are prime factors of the denominator, and the numerator is greater than a y – a – y, then the decomposition is always possible. If the denominator consists of three or more prime factors, b then making it equal to + 7+ . + &c. the decomposition may still be effected by means of an indeterminate equation of the first degree. But the principal use of this decomposition is in the inverse method of fluxions, or the integral calculus, for which purpose they were first investigated by Leibnitz, and have been since much extended by the researches of Cotes, Euler, Simpson, Lagrange, &c. RAtion AL Quantities, in Algebra, are those which are ex- pressed without any radical signs, being equivalent to integers, or fractions, in arithmetic, which are called rational numbers, or quantities, in contradistinction to irrational or surd quanti- ties. See SURDS. RATIONAL Horizon. See Horizon. RATIONALE, a solution or account of the principles of some opinion, action, hypothesis, phenomenon, or the like. RATLINES, small lines which traverse the shrouds of a ship horizontally at regular distances from the deck upwards, and forming a variety of ladders whereby to climb or to descend from any of the mast-heads. - - To rattle down the Shrouds, is to fix the ratlines to them in order to prevent them from slipping down by the weight of the sailors; they are firmly attached by a knot called a clove hitch, to all the shrouds except the fore-most or aft-most. RAURAVA, a Sancrit word meaning dreadful, and a name of one of the Hindoo hells. They reckon twenty-one of these receptacles for sinners, of which the Naraka is the most dreadful. RAVELIN, in Fortification, was anciently a flat bastion, composed only of two faces which make a saliant angle, without any flanks, and raised before the curtain on the counterscarp of the place. A ravelin is a triangular work, resembling the point of a bastion with the flanks cut off. RAVEN. See CoRVUs. r RAVISHMENT, in Law, denotes an unlawful seducing either a woman or an heiress in ward, for which there is a remedy by a writ of ravishment, or action of trespass, in the same manner as the husband may have it on account of the abduction of his wife. RAW, in Agriculture, denotes any sort of plant, sub- stance, or material, which is green, unripe, or in an undi- gested condition. Hence, raw land, raw cream, raw hide, raw silk, &c. RAY, in Optics, a beam of light propagated from a radiant point. If the ray comes direct from the radiant point to the eye, it is said to be direct ; if it first strike upon any body, and is hence transmitted to the eye, it is said to be reflected, and the ray itself is called a reflected ray ; and if the ray in its passage to the eye be bent or turned out of its direct course by passing through any medium, it is said to be refracted, and is thence called a refracted ray. When two or more rays proceed in directions parallel to each other, they are called parallel rays. If they converge towards each other, they are called converging *ays, and if they diverge, diverging rays ; and those which pass directly to the eye in any case, are called visual rays. Among other qualities of rays it has been found, by experiment, that there is a very great difference in the heating power of the different rays from the sun. It appears from the experiments of Dr Herschel, that the heating power increases from the middle of the spectrum to the red rays, and is greatest beyond it where the rays are invisible. Hence it is inferred, that the rays of light and caloric nearly accompany each other, and that the latter are in different pro- portions in the different coloured rays; these are easily sepa- rated from each other, as when the sun’s rays are transmitted through a transparent body, the rays of light pass on seemingly undiminished, but the rays of caloric are intercepted. When the sun's rays are directed to an opaque body, the rays of light are reflected, and the rays of caloric are absorbed and retained. This is the case with the light of the moon, which, however much it be concentrated, gives no indication of being accom- panied with heat. It has also been shewn, that the different rays of light produce diſſerent chemical effects on the metallic salts and oxides. These effects increase on the opposite direc- tion of the spectrum, from the heating power of the rays. From the middle of the spectrum, towards the violet end, they become more powerful, and produce the greatest effect beyond the visible rays. From these discoveries it appears, that the solar rays are of three kinds. 1. Rays which produce heat. 2. Rays which produce colour; and 3. Rays which deprive metallic substances of their oxygen. The first set of rays is in greatest abundance, or are most powerful towards the red end of the spectrum, and are least refracted. The second set, or those which illuminate objects, are most powerful in the middle of the spectrum. And the third set produce the greatest effect towards the violet end, where the rays are most refracted. The solar rays pass through transparent bodies without increasing their temperature. The atmosphere, for instance, receives no increase of temperature, by transmitting the sun's rays, till these rays are reflected from other bodies or are communicated to it by bodies which have absorbed them. This is also proved by the sun's rays being transmitted through convex lenses, producing a higher degree of temperature when they are con- centrated, but giving no increase of temperature to the glass itself. By this method, the heat which proceeds from the sun can be greatly increased. Indeed, the intensity of temperature produced in this way, is equal to that of the hottest furnace. This is done either by reflecting the sun's rays from a concave polished mirror, or by concentrating, or collecting them by the refractive power of convex lenses, and directing the rays thus concentrated on the combustible body. See BURNING Glass. RAY, or Rye GRAss, in Agriculture, a valuable sort o early grass, that has been long, and still is much cultivato in some districts. w 876. R. E. B R E O DICTIONARY OF MECHANICAL SCIENCE, RAZOR, a well known keen edged instrument used in shav- ing. Heat appears to give a partial increase of tenacity to a razor's edge, but the reason has not been satisfactorily assigned. . . . - REACH, in Sea Language, signifies the distance between any two points of land, lying nearly in a right line. - REACTION, in Physics, the action by which a body acte upon returns the action by a reciprocal one upon the agent. ReAction, in Physiology, the resistance made by all bodies to the action or impulse of others, that endeavour to change their state whether of motion or rest. - REAGENT. In the experiments of chemical analysis, the component parts of bodies may either be ascertained in quan- tity as well as quality, by the perfect operations of the laboratory, or their quality alone may be detected by the operations of cer- tain bodies called reagents. Thus the infusion of galls is a re- agent, which detects iron by a dark purple precipitate; the prus- siate of potash exhibits a blue, with the same metal, &c. REALGAR, in Chemistry. tinction of which is not very accurately determined. That which has been named realgar is of a red colour, sometimes inclining It occurs massive, dissemi- mated, and crystallized, in oblique tetrahedral or hexhaedral prisms, generally small and translucent, or semitransparent, Its fracture is uneven ; it is soft and to a Scarlet, sometimes to orange. with a shining lustre. brittle, and has a specific gravity of 3:2, or 3-3. It exhales before the blow-pipe with a white arsenical and sulphurous odour, and gives a blue flame. It consists of arsenic and sul- phur in the proportions of 80 of the former, and 20 of the latter. REALISTS, a sect of school philosophers, who followed the doctrine of Artistotle with respect to universal ideas, in oppo- sition to the Nominalists, who embraced the hypotheses of Zeno and the Stoics. - REAPING, in Agriculture, the operation of cutting crops either of corn, pease, beans, flax, &c. by means of a sickle or a reaping-hook. Several attempts bave been made to construct reaping machines, but they have not hitherto been crowned with much success. REAR, a name given to the last division of a squadron, or the last squadron of a fleet, and which is accordingly command- ed by a third officer of the said squadron or fleet. REASON, a faculty or power of the soul, by which it dis- tinguishes good from evil, truth from falsehood; or, on com- paring several things together, by which we draw consequences from the relations they are found to have. Mr. Locke observes, that reason comprehends two distinct faculties of the mind, namely, sagacity, by which it finds intermediate ideas, and illation, by which it so orders and arranges them, as to discover what connexion there is in each link of the chain by which the extremes are held together. By these means it draws into view the truth which was sought. All our ideas are either according to reason, above its comprehension, or contrary to its dictates. The first must be true, the second may be true, but the third cannot, and on this account should be rejected. Rea- son, as contradistinguished from faith, is the discovery of the certainty or probability of such propositions as it has obtained by the use of its natural faculties. Faith, on the other hand, is the assent of the mind to any given proposition upon the credit of the proposer. Thus Revelation is received as com- ing immediately from God. REASONING, the exercise of the faculty of the mind called reasoning; or it is an act or operation of the mind, deducing some unknown proposition from other previous ones that are evident and known. REAUMUR, RENE ANToINE, a celebrated French philoso- sopher, was born at Rochelle, in 1683. He was author of several works, but none that requires any mention in this article. He invented the thermometer which bears his name, a description of which is given under that article. Reaumur died in 1757. - - REBATE, or ReBATEMENT, in Commerce, a term much used at Amsterdam, for an abatement in the price of several com- modities, when the buyer, instead of taking time, advances rea- dy money. • , - Arsenic mineralized by sulphur forms two ores, named orpiment and realgar, the chemical dis- REBELLION. taking up arms traitorously against the king, be it by natural subjects, or by others once subdued. REBELLION, originally signified, among the Romans, a rising of such persons or tribes as had been formerly overcome in battle, and had yielded themselves to their subjection. It is now generally understood as a traitorous taking up arms against the king, either by his natural subjects, or by commu- nities that had been subdued. Much, however, depends on the issue; a successful revolt makes a revolution, an unsuc- cessful one is rebellion. - REBUTTER, is the answer of the defendant to the plain- tiff’s sur-rejoinder. - RECAPITULATION, in Oratory, &c. is a summary, or a concise and transient enumeration of the principal thing insist- ed on in the preceding discourse, whereby the force of the whole is collected into one view. RECAPTION. Where one has deprived another of his pro- perty, the owner may lawfully claim and retake it wherever he happens to find it, so that it shall not be in a riotous manner, or attended with any breach of the peace. * . RECEIPTS, are acknowledgments in writing of having received a sum of money or other value. A receipt is either a voucher for an obligation discharged or one incurred. Receipts for money above 40s. must be on stamps; but on the back of a bill of exchange or promissory note which is already stamped is good without a further duty. Writing a receipt on a stamp of greater value than the law requires, incurs no penalty, and the receipt is good ; but if on a stamp of a lower value, or on unstamped paper, then a receipt is no discharge, and incurs a penalty. RECEIVER, Receivers are chemical vessels which are adapted to the necks or beaks of retorts, alembics, and other distillatory vessels, to collect, receive, and contain the products of distillations. Receive R, in Pheumatics, a glass vessel for containing the thing on which any experiment in the air-pump is to be made. RECESSION. See PRECESSION. - RECIPE, in Medicine, a prescription or remedy to be taken by a patient, so called because always beginning with the word recipe, i. e. take ; which is generally denoted by the abbrevi- ature R. RECIPIANGLE, or Reci PIENT ANGLE, a mathematical instrument, serving to measure re-entering and saliant angles especially in fortification. RECIPROCAL, in Arithmetic and Algebra, is the quotient arising from dividing unity by any quantity; thus 1 -- 3/ Q: ReciprocAL Equations, are those which contain several pairs of roots, which are the reciprocal of each other. RecipRocAL Figures, in Geometry, are such as have the antecedent and consequents of the same ratio in both figures. ReciprocAL Proportion, is when the reciprocal of the two last terms have the same ratio as the quantities of the first terms, or when the antecedents are compared with the recipro- cals of the consequents, thus, 5 : 8 :: 24 : 15 is a reciprocal proportion, because 5 : 8 : ; ; ; ;, or 5 : * : : 8 : 13. Reci PRocAl Ratio, is the ratio of the reciprocals of two Quantitics. ReciprocAL Terms, among Logicians, are those which have the same signification; and consequently are convertible, or may be used for each other. - RECIPROCALLY, the property of being reciprocal ; thus we say, that in bodies of the same weight, the density is reci- procally as the magnitude, viz. the greater the magnitude the less the density; and the less the magnitude, the greater the density. So again, the space being given, the velocity is reci- procally as the time. * RECIPROCITY. The law of reciprocity is a term employed by Legendre in his “Theory of Numbers,” to denote a recipro- cal law that has place between prime numbers of different forms, which is this, that m and n being prime odd numbers, 7m — 1 - 27, - 1 the remainder of m 2 divided by n = the remainder of 1 3 Q: is the reciprocal of the fraction I- - * - divided by m; if m and n are not both of the form 4a – n, and R E C R E D 877 DICTIONARY OF MECHANICAL SCIENCE. 21 — 1 1f they are both of this form, then the remainder of m 2 divi- 777 – 1 - ded by n = — the remainder of n 2 divided by m; but with a contrary sign. RECITATIVO or RR cit Ative, in Music, a kind of singing that diſſers but little from ordinary pronunciation, such as that in which the several parts of the liturgy are rehearsed in cathe- drals; or that in which the actors commonly deliver themselves on the theatre at the opera, when they are to express some action or passion, to relate some event, or reveal some design. RECKONING, the art of estimating the quantity of a ship's way, or of the distance run between one place and another. Or more generally, a ship's reckoning is that account whereby at any time it may be known where the ship is, and on what course or courses she is to steer to gain her port. This is usually performed by means of the log-line. See LoG-LIN e. Yet this is sub- ject to great irregularities. Vitruvius advises an axis to be passed through the sides of the ship with two large heads pro- pending out of the ship, wherein are to be included wheels touching the water, by whose revolution the space passed over in any given time may be measured. The same has been since recommended by Snelling, but there are few who have written on navigation but have shewn the insufficiency of this method. RECLUSE, among religious, signifies a person shut up in a very narrow cell or hermitage, and secluded from all inter- course with the world and mankind. RECLINER, in Dialling, is used for any dial whose plane reclines from the perpendicular; and if besides reclining, it also declines from any of the cardinal points, it is called a reclining declining dial, and the quantity or angle at which it declines or reclines, is called its reclination or declination. - RECOGNIZANCE, in Law, is an obligation of record which a man enters into before some court of record, or magistrate duly authorized, with condition to the same particular act, as to ap- pear at the assizes or quarter sessions to keep the peace, &c. If the party does not comply with it, the recognizance is estreated into the exchequer. In some cases the court will upon motion respite, and in some discharge the recognizance; but all par- ties should be careful to apply in good time to the court where the recognizance is to be returned. RECOIL, or ReBoun D, the starting backward of a fire-arm, after an explosion. This term is particularly applicable to pieces of ordnance, which are always subject to a recoil, accord- ing to the sizes and the charges which they contain. To lessen the recoil of a gun, the platforms are generally made sloping towards the embrasures of the battery. RECORD, an act committed to writing in any of the king's courts during the term wherein it is written, is alterable, being no record ; but that term once ended, and the act duly enrolled, it is a record, and of that credit which admits of no alteration or proof to the contrary. RECORDARI FACIAs, a writ directed to the sheriff, to re- move a cause out of an inferior court, into the king's bench or common-pleas. RECORDE, Robert, an eminent English mathematician, of the 16th century, author of several works on arithmetic, alge- bra, geometry, &c. and which were principally written in the form of dialogues between a master and his pupils. RECORDER, a person whom the mayor and other magis- trates of a city or corporation associate to them, for their better direction in matters of justice and proceedings in law; on which account, this person is generally a counsellor, or other person well skilled in the law. RECOVERY, in Law, is obtaining any thing by judgment or trial at law. A recovery resembles a fine so far as being an action real or fictitious, and in that lands are recovered against the tenant of the freehold, and an absolute fee-simple is vested in the recovery ; but it is carried on through every stage of proceeding, instead of being compromised Hike a fine. RECTANGLE, in Geometry, the same with a right-angled parallelogram. - RECTANGULAR FIGUREs and SolIDs, are those which have one or more right angles. With regard to solids, they are commonly said to be rectangular when their axis are per- pendicular to the planes of their bases. See “Essai sur la Théorie des Nombres,” p. 3. . of birds of the order grallac. There are three species. V. RecTANGULAR Section of a Cone, was a term used by the ancients, before Apollonius, for the parabolic section. RECTIFICATION, in Geometry, is the finding of a right line equal to a proposed curve; a problem that even in the present state of analysis is, in many cases, attended with some difficul- ty, and was in all totally beyond the reach of the ancient geome- ters, who were not able to assign the length of any curve line whatever, though they could, in a few cases, assign the area of a curvilinear space. It is to the doctrine of fluxions that we owe the complete rectification of curve lines, in finite terms, in all cases where they admit of it, and in others by means of infinite series, circular arcs, logarithms, &c. Rect ific Ation, in Chemistry, the repetition of a distillation or sublimation several times, in order to render the substances purer, finer, and freer from aqueous or earthy parts. RECTIFIER, an instrumunt used for determining the varia- tion of the compass, in order to rectify the ship's course, &c. It consists of two circles, either laid upon or let into one another, and so fastened together in their centres, that they represent two compasses, the one fixed, the other moveable; each is divided into 32 points of the compass, and 360 de- grees, and numbered both ways, from the north and the south, ending at the east and west, in ninety degrees. The fixed compass represents the horizon, in which the north and all the other points are liable to variation. In the centre of the moveable compass is fastened a silk thread, long enough to reach the outside of the fixed compass ; but if the instru- ment be made of wood, an index is used instead of the thread. RECTILINEAR, in Geometry, right-lined: thus figures whose perimeter consists of right lines are said to be rectilinear. RECTORY, a parish, church, parsonage, or spiritual living, with all its rights, tithes, and glebes. RECTUM, in Anatomy, is the last portion of the large intes- tine, and of the whole alimentary canal. This part of the human body is subject to disease, chiefly with those advanced in years, but young persons swallowing plum and cherry stones are not exempt. RECURRING SERIES, is a series so constituted that each succeeding term is connected with a certain number of the terms immediately preceding it by a constant and invariable law; as the sums or differences of some multiples of those terms, &c. RECURRING Deci MALs, those which are continually re- peated in the same order, at certain intervals, as # = 6666, and * = .272727, &c. RECUSANT, a person who refuses to go to church, and worship God after the manner of the chureh of England, as by law established ; to which is annexed the penalty of 20l. a month for nonconformity. 24 Eliz. c. 1. . RECURVIROSTRA, the Avoset in Natural History, a genus The scooping avoset, found in this island, as large as the lapwing, has extremely long legs; its bill is three inches and a half in length. In winter it is often seen at the mouth of the Severn and on the coasts of Suffolk. In the fems of Cambridgeshire these birds are known to breed, and appear often in vast flocks. Their subsistence is on insects and worms, which they procure from the soft muddy bottoms with their bills. They often wade into the water to the top of their legs, and are able to swim ; but are seldom seen swimming, and never, unless at a very small distance from the shore. In France, on the coasts of Bas Poictou, their nests are plundered annually of several thousands of eggs, which form a nourishing and valu- able food for the peasantry of that district. RED. See COLOUR. - RED, in Physics, or Optics, one of the simple or primary colours of natural bodies, or rather of the rays of light. The red rays are the least refrangible of all the rays of light. And hence, as Newton supposes, the different degrees of refrangibi- hity to arise from the different magnitudes of the luminous par- ticles of which the rays consist; therefore the red rays, or red light, is concluded to be that which consists of the largest parti- cles. See Colour and LIGHT. Authors distinguish three general kinds of red, one bordering on the blue, as colombine, or dove colour, purple, and crimson; another bordering on yellow, as flame colour and orange ; and between these ex- tremes is a medium, which is that which is properly called red. 10 O - 878 R. E. E. R. E. D DICTIONARY OF MECHANICAL SCIENCE, Red Clover, in Agriculture, an useful artificial grass fitted for arable lands. It has this name to distinguish it from white clo- wer and some other sorts. . . . * - Red Shank, in Ornithology, a bird about the size of the com- mon plover. On the back its colour is of a gray or brownish green, spotted with black; its breast white; wings and throat variegated. It breeds in fens and marshes, and during the win- ter season lies concealed in gutters. Its bill is about two inches long, and in shape resembles that of a woodcock. * Red Start, in Ornithology, is a beautiful bird, exquisite in plumage, moves its tail horizontally like a dog when fawning, has black legs, is remarkably shy, but has a soft and melodious note. It is migratory, and is found in this country only in spring and summer. Red Wing, in Ornithology, a bird somewhat smaller than the thrush, and is less spotted. It is a-bird of passage, coming on the approach of winter, supposed from the mountains of Ger- many and Bohemia. - . . - RED Water, a disease in sheep, supposed to be caused by their taking too much watery food, such as turnips, clover, rape, &c. Its removal has been attempted by the use of common salt, a tea-spoonful of elixir of vitriol, and keeping the animals in action. A proportion of dry food is the best preventive. Red Weed, is a name sometimes given to the round smooth- headed poppy, a pernicious weed in corn-fields. $ Red Worm, the name of an insect very destructive to young corn crops. Many experiments have been made on the best means of destroying it, but none have been found altogether effectual. . - . - RED-BOOK, of the Exchequer, an ancient record or manu- script volume, in the keeping of the king’s remembrancer, con- taining divers miscellaneous treatises relating to the times be- fore the Conquest. - REDDENDUM, in our Law, is used substantively for the clause in a lease wherein the rent is reserved to the lessor. REDDLE, Red Och Re, or Red Chalk, in Mineralogy, the red oxide of iron united with earthy matter. It is used for. crayons either in its natural state, or pulverized, washed, and afterwards mixed with gum, and cast into moulds. REDEMPTION, in Law, a faculty or right of re-entering upon lands, &c. that have been sold and assigned, upon re-im- bursing the purchase-money with legal costs. Bargains wherein the faculty, or as some call it, the equity of redemption is re- served, are only a kind of pignorative contracts. REDEMPtion, in Theology, denotes the recovery of mankind from sin and death, by the obedience and sacrifice of Christ, who is hence called the Redeemer of the world. REDOUBT, or Redoute, in Fortification, a small square fort, without any defence but in front, used in trenches, lines of circumvallation, contravallation, and approach, as also for the lodgings of corps de garde, and to defend passages. In marshy grounds, redoubts are frequently made of stone-works for the security of the neighbourhood ; their face consists of from 10 to 15 fathoms, the ditch round them from 8 to 9 feet broad and deep, and their parapets have the same thickness. RED SNOW. The phenomenon of red snow, seen both on the coast of Baffin's bay and at Spitzbergen, has attracted much attention. This colouring matter has been found to have its origin from a very minute fungus which grows upon the snow, and which has been considered a species of uredo, and has been denominated uredo nivalis, REDUCING SCALE, or Surveying Scale, is a broad thin slip of box, or ivory, having several lines and scales of equal parts upon it; used by surveyors for turning chains and links into roods and acres by inspection. It is used also to reduce maps and draughts from one dimension to another, REDUCTION, in Arithmetic, is, by some authors on this subject, distinguished into reduction ascending, and reduction descending. The former, relating to the conversion of a quan- tity from a lower denomination to a higher; and the latter, when the quantity is to be reduced from a higher denomination to a lower. . . - X- REDUCTION, or Revivification. This word, in its most extensive sense, is applicable to all operations by which any substance is restored to its natural state, or which is considered as such ; but custom confines it to operations by which metals are restored to their metallic state, after they have been de- prived of this, either by combustion, as the metallic oxides, or | by the union of some heterogeneous matters which disguise them, as fulminating gold, luna cornea, cinnabar, and other compounds of the same kind. These reductions are also called revivifica- tions. - * * t - - REDUNDANT HYPER Bol A, one of the higher order of hyperbolas, having more than two infinite branches. REED, in Agriculture, the name of an aquatic plant infest- ing boggy low lands or meadows on the sides of rivers. Trench- es, draining off the moisture by which it is supported, will de- stroy it. Ashes or soot has sometimes killed this weed. Reed, is also a term applied to such straw of wheat, oats, or rye, as has not been damaged by thrashing. - - Reed Hedge, in Gardening, is a hedge-fence which is formed of reeds. It is temporary and moveable, furnishing shelter to many seedlings and plants. - - - Reeds, in Fireships, are made up in small bundles of about twelve inches in circumference, cut even at both ends, and dip- ped in a kettle of melted composition, to render them easily ignitible. > . REEF, a certain portion of a sail comprehended between the top or bottom and a row of eyelet holes generally parallel thereto. The intention of the reef is to reduce the surface of the sail in proportion to the increase of the wind, for which reason there are several reefs parallel to each other in the superior sails; thus the top sails of ships are generally furnished with three reefs, and sometimes four, and there are always three or four reefs parallel to the foot or bottom of those main- sails and fore-sails which are extended upon booms. . REEF, also implies a chain of rocks lying near the surface of the water. - - : Reef Band, a piece of canvass sewed across the sail to strengthen it in the place where the eyelet holes of the reefs are formed. . - REEF-Line, a small rope, by which they formerly reefed the courses by passing it spirally through the holes of the reef, and over the head of the sail, alternately from the yard arms to the slings, and then straining it as tight as possible. REEF-Tackle, a tackle upon deck, communicating with its pendant, which passing through a block at the top-mast-head, and through a hole in the top-sail yard-arm, is attached to a cringle a little below the lowest reef. Its use is to pull the skirts of the top-sails close up to the extremities of the top-sail yards, in order to lighten the labour of reefing. Close-REE FED, is when all the reefs of the top-sails are taken in. REEFING, the operation of reducing a sail by taking in one or more of the reefs, and is either performed with lines, points, or knittles. The top sails are always and the courses generally reefed with points, which are flat braided pieces of cordage, whose lengths are nearly double the circumference of the yard. These being inserted in the eyelet holes, are fixed in the sail by means of two knots in the middle, one of which is before and the other behind the reef-band. In order to reef the top-sańs with more facility and expedi- tion, they are lowered down, and made to shiver in the wind ; the extremities of the reef are then drawn up to the yard- arms by the reef-tackles, where they are securely fastened by the earings; the space of sail comprehended in the reef is then laid smoothly over the yard in several folds, and the whole is completed by tying the points about the yard so as to bind the reef up close to it. In reeſing a course, the after end of the point should be thrust forward between the head of the sail and the yard, and the fore leg of the same point should come aft over the head of the sail, and also under the yard, and thus crossed over the head of the sail, the two ends should be tied on the upper side of the yard as tight as possible. When a sail is reefed at the bottom, it is generally done with knittles in the room of points, or in large sails, such as the main sails of armed cutters, pieces of line, termed reef- hanks, are fixed in the eyelet-holes. -- REEL, in the manufactories, a machine serving for the office of reeling. There are various kinds of reels, some very simple, others very complex. Of the former kinds those most in use are, 1. A little reel held in the hand, consisting of three pieces of wood, the biggest and longest whereof, (which does R. E. F. R. E. F DICTIONARY OF MECHANICAL scIENCE. 879 not exceed a foot and a half in length, and one-fourth of an inch in diameter) is traversed by two other pieces disposed different ways. 2. The common reel or windlass, which turns upon a pivot, and has four flights: traversed by long pins or sticks, whereon the skein to be reeled is put, and which are drawn closer or opened wider according to the skein. - REELING, in the Manufactories, the winding of thread, silk, cotton, or the like, into a skein. - REELS, are machines moving round an axis, and serving to wind various lines upon, as the Deep-Sea-Reel, that which contains the deep-sea line; Log-REEL, that appropriated for the log-line. Rectific Ation, in Chemistry, the repetition of a distillation or sublimation several times, in order to render the substances purer, finer, and freer from aqueous or earthy parts. REEM. See RHINO C E Ros. REEMING, a term used by caulkers for opening the seams of the planks with irons, for the more easy admission of oakum. In common language, to make any hole larger, is in many places termed reeming. - RE-ENTRY, in Law signifies the resuming or retaking the possession of lands lately lost. REEVING, in the Sea Language, the putting a rope through a block; hence to pull a rope out of a block is called unreeving, REFERENCE, in Law, is where a matter is referred by the court of chancery to a master, and by the courts at law to a prothonotary, or secondary, to examine and report to the court. Reference also signifies where a matter in dispute is referred to the decision of an arbitrator. This is done either by parol, agreement, or by bond, or upon a suit, in which latter case the party has a rule of court, that the party against whom the award is made shall perform it, and then he may move to have an attachment against him, if he does not perform it. By statute also this may be done, where the parties agree that the award should be made a rule of court, although there is no suit. - * . ºf REFINING, in general, is the art of purifying a thing; including not only the assaying or refining of metals, but like- wise the depuration or clarification of liquors. Gold and silver may be refined by several methods, which are all founded on the essential properties of the metals, and acquire different names according to their kinds. * REFINING, in Metallurgy, is the means of obtaining me- tals from their ores, and freeing them from all other impurities, whether natural or artificial. The term is applicable to the purification of things in general. REFITTING, in sea language, is generally understood to imply the repairing any damages which a ship may have sus- tained in her sails or rigging by battle or tempest, but more particularly by the former. - - - REFLECTION, or REFLEXION, in Mechanics, is the return or regressive motion of a moveable body, arising from the re- action of some other body on which it impinges. The reflec- tion of bodies after impact is attributable to their elasticity, and the more perfectly they possess this property, the greater will be their reflection, all other things being the same. In case of perfect elasticity, they would be reflected back again with the same velocity, and at an equal angle with which they met the plane ; that is, the angle of incidence would be equal to the angle of reflection, and the velocity both before and after im- pact would be the same, at equal distance from the body on which they impinge. Reflection of the Rays of Light, in Catoptrics, is their return, after their approaching so near the surfaces of bodies as to be repelled or driven backwards. See Optics. - Reflection of Heat. In the same manner as we find the rays of light are reflected by polished surfaces, so it is found that the rays of caloric have precisely the same property. The Swedish chemist, Scheele, discovered, that the angle of reflec- tion of the rays of caloric is equal to the angle of incidence, a fact which has been more fully established by Dr. Herschel. Some very interesting experiments were made by Professor Pictet, of Geneva, which proved the same thing. These expe- riments were conducted in the following manner:—Two con- cave mirrors of tin, of nine inches focus, were placed at the distance of twelve feet two inches from each other; in the focus of the one was placed the bulb of a thermometer, and in that of the other a ball of iron two inches in diameter, which was just heated so as not to be visible in the dark. In the space of six minutes the thermometer rose 22°. . A similar effect was pro- duced by substituting a lighted candle in place of the ball of iron. Supposing that both the light and heat might act in the last experiment, he interposed between the two mirrors a plate of glass, with the view of separating the rays of light from those of caloric. The rays of caloric were thus interrupted by the plate of glass, but the rays of light were not perceptibly diminished. In nine minutes the thermometer sunk 149; and in seven minutes after the glass was removed, it rose about 12°. He therefore justly concluded, that the caloric reſlected by the mirror was the cause of the rise of the thermometer. He made ..another experiment, substituting boiling water in a glass vessel in place of the iron ball; and when the apparatus was adjusted, and a screen of silk, which had been placed between the two mirrors, removed, the thermometer rose 3°; namely, from 47° to 50°. The experiments were varied by removing the tin mir- rors to the distance of 90 inches from each other. The glass vessel, with boiling water, was placed in one focus, and a sen- sible thermometer in the other. In the middle space between the mirrors, there was suspended a common glass mirror, so that either side could be turned towards the glass vessel. When the polished side of this mirror was turned towards the glass vessel, the thermometer rose only five-tenths of a degree ; but when the other side, which was darkened, was turned towards the glass vessel, the thermometer rose 3° 5'. And in another experiment, performed in the same way, the thermo- meter rose 3° when the polished side of the mirror was turned to the glass vessel, and 9° when the other side was turned, which experiments shew clearly, that the rays of caloric are reflected from polished surfaces, as well as the rays of light. Transparent bodies have the power of refracting the rays of caloric as well as those of light. They differ also in their refran- gibility. So far as experiment goes, the most of the rays of caloric are less refrangible than the red rays of light. The ex- periments of Dr. Herschel shew that the rays of caloric, from hot or burning bodies, as hot iron, hot water, fires, and can- .dles, are refrangible, as well as the rays of caloric which are emitted by the sun. Whether all transparent bodies have their power of transmitting these rays, or what is the difference in the refractive power of these bodies, is not yet known. The light which proceeds from the sun seems to be composed of three distinct substances. Scheele discovered that a glass mirror, held before the fire, reflected the rays of light, but not the rays of caloric ; but when a metallic mirror was placed in the same situation, both heat and light were reflected. The mirror of gºss became hot in a short time, but no change of tem- perature took place on the metallic mirror. This experiment shews that the glass mirror absorbed the rays of caloric, and reflected those of light; while the metallic mirror, suffering no change of temperature, reflected both. And if a plate of glass be held before a burning body, the rays of light are not sensibly interrupted, but the rays of caloric are intercepted ; for no sensible heat is observed on the opposite side of the glass; but when the glass has reached a proper degree of temperature, the rays of caloric are transmitted with the same facility as those of light. And thus the rays of light and caloric may be sepa- rated; and the curious experiments of Dr. Herschel have clearly proved, that the invisible rays which are emitted by the sun have the greatest heating power. In these experiments, the different coloured rays were thrown on the bulb of a very deli- cate thermometer, and their heating power was observed. That of the violet, green, and red rays, were found to be to each other as the following numbers :— Violet, 16 0;.... Green, 22 4;.... Red, 550. The heating power of the most refrangible rays was least, and this increases as the refrangibility diminishes. The red ray, therefore, has the greatest heating power, and the violet, which is the most refrangible, the least. The illuminating power, it has been already observed, is greatest in the middle of the spectrum, and diminishes towards both extremities; but the heating power, which is least at the violet end, increases from that to the red extremity, and when the thermometer was placed beyond the limit of the red ray, it rose still higher than in the 880 R. E. G. R. E. F. DICTIONARY OF MECHANICAL SCIENCE. red ray, which has the greatest heating power in the spectrum. The heating power of these invisible rays was the greatest at the distance of half an inch beyond the red ray, but it was sensible at the distance of one inch and a half. REFLECTING CIR cle, an astronomical instrument for mea- suring angles. It is called reflecting from its property, in com- mon with the Hadley's quadrant, (of which it is a modification) of observing one of the objects of the angle to be measured by • distinct vision, and the other by reſlection of plane mirrors. REFLECTOIRE CURve, is a term given by Mairan to the curvilinear appearance of the plane surface of a bason contain- ing water to an eye placed perpendicularly over it. In this position the bottom of a bason will appear to rise upwards from the centre outwards, but the curvature will be less and less, and at last the surface of the water will be an asymptote to it. REFLECTOR, a mirror or looking-glass. REFLEXIBILITY, the property necessary for reſlection. REFLUX of the Se A. See TID e. REFORM, a revival of former discipline, a re-establishment of partially neglected or abandoned principles, or a correction of some reigning abuses in them. REFORMATION, the act of correcting abuses. More em- phatically, the term is applied to the throwing off the papal yoke, about the beginning of the sixteenth century. To this no- ble act we are indebted for the religious privileges we enjoy, and many of our civil blessings may be traced to the same SOUIrC6, REFRACTED ANgle, or Angle of Refraction, is the angle which a refracted ray makes with the surface of the refracting body. The complement of this angle is, however, sometimes called the refracted angle. REFRACTION of the rays of light. See Optics. Refraction, in Astronomy, is an inflection of the rays of light proceeding from the heavenly bodies, in passing through the atmosphere by which their apparent altitudes are increased. Atmospherical Refrt Action. It is evident, from the nature and progression of light, that rays, in passing from any object through the atmosphere, or part of it, to the eye, do not pro- ceed in a right line; but the atmosphere being composed of an infinitude of strata, (if we may so call them,) whose density increases as they are posited nearer the earth, the luminous rays which pass through it are acted on as if they passed succes- sively through media of increasing density, and are, therefore, inflected more and more towards the earth as the density aug- ments. In consequence of this it is, that rays from objects, whether celestial or terrestrial, proceed in curves which are concave towards the earth : and thus it happens, since the eye always refers the place of objects to the direction in which the rays reach the eye, that is, to the direction of the tangent to the curve at that point, that the apparent or observed eleva- tions of objects are always greater than the true ones. The difference of these elevations, which is in fact the effect of refraction, is, for the sake of brevity, called refraction ; and it is distinguished into two kinds, horizontal, or terrestrial, re- fraction, being that which effects the altitude of hills, towers, and other objects on the earth's surface; and astronomical refraction, or that which is observed with regard to the altitudes of heavenly bodies. Refraction is found to vary with the state of the atmosphere in regard to heat or cold, and humidity, so that determinations obtained for one state of the atmosphere, will not answer correctly for another without modification. Tables commonly exhibit the refraction at different altitudes, for some assumed mean state. Reft Action of Altitude, is an arc of a vertical circle, by which the altitude of a star is increased by the refraction. Refraction of Ascension or Descension, is an arc of the equa- tor by which the ascension or descension, whether right or oblique, is increased or diminished by refraction. Refr ACTio N of Declination, is the increase or decrease in the declination of a star by refraction. Refraction, in Latitude, is the increase or decrease of the latitude of a star from refraction. Refit Action, in Longitude, is the increase or decrease in the longitude of a star from refraction. Ref RACTION, in Mechanics, is the deviation of a body in motion, from its direct course, in consequence of the variable density of the mediums in which it moves. This, however, except in speaking of the rays of light, is commonly called deflection. - Refit Action, in Iceland crystal. There is a double refrac- tion in this substance, contrary ways, by which not only oblique rays are divided into two, and refracted into opposite parts, but even perpendicular rays are one half refracted. REFRANGIBILITY of Light, the property of the rays to be refracted, but more commonly employed with reference to the different degrees in which the different rays possess, this property; and on which Newton has founded his whole theory of colours. For the several experiments relating to this sub- ject, see PRiSM. * - REFRIGERATION, the act of cooling, or the abstracting of heat from various substances, for the purpose of art or domes- tic use. REFUGE, in antiquated customs, a sanctuary or asylum. In the Old Testament, six cities of refuge were appointed for the protection of persons from the rigour of the law, who were guilty of involuntary homicide. REFUGEES, French Protestants who, on the revocation of the edict of Nantz in 1685, fled from persecution, and found shelter in Holland, Germany, and England, where they carried many valuable arts, by which these countries have been enrich- ed and France has been empoverished. - REGAL, something belonging to a king. Regal is is also a musical term, and likewise a species of portable organ much used in processions in papal countries. REGALE, in French jurisprudence, is a right belonging to the king over all benefices in that kingdom. It consists in the enjoyment of the revenues of bishops' sees during their vacancy, and in the presentment to benefices dependent on them. REGALIA, in Law, the rights and prerogatives of a king, which, according to the civilians, are six, viz. l. The power of judicature; 2. the power of life and death ; 3. the power of peace and war; 4. a right to such goods as have no owner, as waifs, estrays, &c. 5. assessments; and 6. the coinage of money. Regalia is also used for the apparatus of a coronation, as the crown, the sceptre with the cross, and with the dove, St. Ed- ward's staff, the globe, and the orb with the cross, four several swords, &c. REGARDANT, in Heraldry, is understood of a lion or other beast of prey, in the attitude of looking behind him with his eyes towards his tail. ReGARDANT Villain, an ancient servant or retainer to the lord, because charged with the base stryices within the manor, to see that all filth and nuisances are removed. . REGARDER of the Foſtest, an ancient officer, whose busi- ness it was every year to make oath to the limits of the forest, and also to inquire into all offences committed within its juris- diction. - REGATTA, a name given in Venice to exhibitions on the water, such as a contest for superiority in rowing and the management of boats. - REGEL, or Rig EL, a fixed star of the first magnitude, in the ſeſt foot of Orion. REGENERATION, in 'Theology, the act of being born again by a spiritual birth, or becoming a child of God, through which the person abandons a course of vice, and leads a life of piety and virtue. REGENT, one who governs a kingdom during the minority or absence of the king. In France the queen mother has the re- gency of the kingdom during the minority of the king, under the title of the queen regent. Regent also signifies a professor of arts and sciences in a college, who has a set of pupils under his care ; but here regent is generally restrained to the lower classes, as regent of rhetoric, regent of logic, &c. those of phi- losophy are rather called professors. The foreign universities are generally composed of doctors, professors, and regents. REGERENDARIUS, among the Romans, was an officer who subscribed and kept a register of all petitions presented to the refect. - t p REGICIDE, a king-killer. The term is also used for the act of murdering the king. It is now generally applied to those persons who were engaged in the trial, condemnation, and exe- cution of Charles I. JR E G SCIENCE. R. E. I DICTION ARY OF MECHANICAL 88.1 REGIMEN, the regulation of diet, and, in a more general sense, of all the nonnaturals, with a view to preserve or restore health. Reg IMEN, in Grammar, that part of syntax or construction which regulates the dependency of words, and the alteration which one occasions in another. REGIMENT, in War, is a body of men, either horse or foot, commanded by a colonel. Each regiment of foot is divided into companies, but the number of companies is not always alike, though our regiments generally consist of ten companies, one on the right, of grenadiers, and another on the left, of light troops. Regiments of horse most commonly consist of six troops, but some have nine. Regiments of dragoons, in time of war, are generally composed of eight troops, and in time of peace of six. . REGINA AURARUM, in Ornithology, a large Mexican bird about the size of an eagle. Its whole body is covered with a plumage of a blackish purple. Its feet are red, its beak like that of a parrot; it feeds on rats, mice, snakes, and other ver- min, and can fly against the fiercest wind. REGION, in Physiology, particular districts on the surface of the globe, disposition of internal strata, and distinguished elevations in the atmosphere, and depths in the sca. Region, in Anatomy, denotes the division of the human body. REGIONARY, in Ecclesiastical History, a title given in the fifth century to persons who had the charge and administration of church affairs within a certain district or region. REGIS, PETER SYLVAIN, a French philosopher, was born in 1632, author of a “System of Philosophy,” in 3 vols. 4to, pub- lished in 1690, and some other works. He died in 1707, at 75 years of age. REGISTER, a public book, in which is entered and recorded memoirs, acts, and minutes, to be had recourse to occasionally, for knowing and proving matters of fact. Of these there are several kinds: as, 1. Registers of deeds in Yorkshire and Mid- dlesex, in which are registered all deeds, conveyances, wills, &c. that affect any lands or tenements in those counties, which are otherwise void against any subsequent purchasers or mort- gagees, &c. but this does not extend to any copyhold estate, nor to leases at a rack-rent, or where they do not exceed 21 years. The registered memorials must be engrossed on parchment, under the hand and seal of some of the grantors or grantees, attested by witnesses who are to prove the signing or sealing of them, and the execution of the deed. But these registers, which are confined to two counties, are in Scotland general, by which the laws of north Britain are rendered very easy and regular. Of these there are two kinds; the one general, fixed at Edinburgh, under the direction of the Lord Register; and the other is kept in the several shires, stewartries, and rega- lities, the clerks of which are obliged to transmit the registers of their respective courts to the general register. No man in Scotland can have a right to any estate, but it must become registered within forty days of his becoming seised thereof; by which means all secret conveyances are cut off. 2. Parish riages, and burials, of each parish. Regist ER, is also used for the clerk or keeper of a register. Of these we have several, denominated from the registers they keep : as, register of the high court of delegates; register of the arches court of Canterbury; register of the court of admi- ralty; register of the prerogative court; register of the garter, &c. Regist ER, in Printing, is disposing the forms on the press, so that the lines and pages printed on one side of the sheet fall exactly on those of the other. Register, among letter-founders, is one of the inner parts of the mould in which the printing types are cast. Its use is to direct the joining of the mould justly together again, after opening it to take out the new-cast letter. REGIUS PRofessors. Henry VIII. founded five lectures in each of our universities, viz. Divinity, Hebrew, Greek, Law, and Physic, the readers of which lectures are in the universi- ties' statutes called regii professores. • - REGLE, in Music, a rule for accompanying the octave ascending and descending in the base, giving to each note of the scale its appropriate harmony in every key. REGLET3, or Riglets, in Printing, are thin slips of wood 90. rcgisters are books in which are registered the baptism, mar- exactly planed to the size of the body of the letter. The smaller sorts are placed between the lines of poetry, and both those and larger are used in filling up short pages, in forming the whites or distances between the lines of titles, and in adjusting the distances of the pages in the chase, so as to form register. REGRATOR, or Reg RATER, in Law, formerly signified one who bought wholesale, or by the great, and sold again by retail; but the term is now used for one who buys any wares or vic- tuals, and sells them again in the same market or fair, or within five miles round it. ReGRATOR, is also used for one who furbishes up old move- ables to make them pass for new. And masons who take off the outside surface of hewn stone, in order to whiten it, or make it look fresh again, are said to regrate. REGRESSION. See RETROGRESSION. REGULAR, denotes any thing that is agreeable to the rules of art; thus we say a regular building, verb, &c. A regular figure in Geometry is one whose sides, and consequently angles, are equal; and a regular figure with three or four sides, is com- monly termed an equilateral triangle or square, as all others with sides are called regular polygons. All regular figures may be inscribed in a circle. A regular solid, called also a platonic body, is that terminated on all sides by regular and equal planes, and whose solid angles are all equal. REGULAR Bodies, are those which have all their sides, angles, and faces, similar and equal. Of these there are only five, viz. the Tetraedon, contained by four equilateral triangles; the Hea'aedron, or cube, by six squares; the Octaedron, by eight triangles; the Dodecaedron, by twelve pentagons; and the Jcosaedron, by twenty triangles. For the propertics of which see the several articles; see also Hutton’s “Mensuration,” sect. 2. REGULATING CAPTAIN, an officer whose duty it is to exa- mine the seamen intended for the navy, whether pressed or volunteers. REGULATOR of a WATCH, the small spring belonging to the balance, serving to adjust its motions, and make it go faster or slower. REGULAtoR of Velocity, in Mechanics, is a contrivance for regulating or governing the motions of a mill, or other machi- nery, causing the motion of its parts to preserve an equable velocity, under all the variations of the propelling cause. REGULUS. The name regulus was given by chemists to metallic matters when separated from other substances by fusion. Reg ULUs, a fixed star of the first magnitude in the coustella- tion Leo ; sometimes called Cor Leonis, or Lion's Heart. By the Arabians it was termed Alhabor, and by the Chaldeans Kalb cleceid. y REHEARING, in the Court of Chancery, is a process to which either party, who thinks himself aggrieved, may have recourse, before the execution of a final decree. REPHEARSAL, in Music and the Drama, is an experiment on some composition in private, that the actors may better understand their parts. º REIGNING WINDs, a name given to the winds which usually provail on any particular coast or region. See WIND. REIMBURSEMENT, in Commerce, the act of repaying what monies had been received by way of advance. A person who gives a bill of exchange in payment, is to reimburse it, if protested, or not paid. REIN DEER, in Zoology. This species of the deer kind is generally described as having horns ramosc, recurvated round with palmated summits. When full-grown, this animal, accord- ing to Pennant, is four feet six inches high, the body of a some- what thick and square form, and the legs shorter than those of the common stag. The general colour is brown above and white beneath, but advancing in age it frequently becomes of a greyish white, and sometimes almost black. Both sexes are fur- nished with horns; those of the male are much larger and longer than those of the female. To the Laplander this animal is con- sidered as the common substitute of the horse, the cow, the sheep, and the goat. The milk furnishes cheese, the flesh food, the skin clothing, the tendons bow-strings, and, when split, thread, the horns glue, and the bones spoons. A Laplander 10 P 882 R. E. L. R E L DICTIONARY OF MECHANICAL SCIENCE. is sometimes possessed of a thousand deer. Their chief food is a species of moss, which covers vast tracts of the northern regions. This they find in abundance during the summer, but in winter their fodder is scarce, and then the greatest care and attention are required for their support. Trained when young to draw the sledge, their services are of the utmost importance when grown to maturity. They will then proceed about thirty miles per day without sustaining any injury, and sometimes, when pressed, from fifty to sixty ; but such journeys generally prove fatal to the animal. The rein deer is a native of the north- ern regions. In Europe its chief residence is Norway and Lapland. In Asia, Siberia and Kamtschatka. In America, Greenland and the neighbourhood of Hudson's Bay, but it is rarely found to the south of Canada. A few years since an attempt was made to introduce the breed into this country, but success did not equal expectation. The common deer are more preserved in England than in any other country. They are said to have been first introduced into Scotland from Norway by James I. and from thence into South Britain. They now abound in almost every county. Of these animals, under the generic term Cervus, there are many species, differing from each other in habit and appearance, the particulars of which may be found in works on matural history. REINHOLD, ERAs MUs, an eminent German mathematician and astronomer, was born in Upper Saxony in 1511, and died in 1553, in his 42nd year. Reinhold was author of several works, of which only the four following were published, viz. 1. Theoriae novae Planetarum G. Purbachii, 8vo. 1542, and again in 1580. 2. Ptolemy's Almagest, the first book in Greek, with a Latin version and Scholia, 8vo. 1549. 3. Prutenica: Tabula Coelestium Mutuum, 4to. 1551 ; 2nd edition in 1571 ; 3d, 1585. 4. Primus Liber Tabularum Directionum, or Tables of Tan- gents, to every minute of the quadrant. And new Tables of Climates, Parallels, and Shadows, with an Appendix, containing the second book of the Canon of Directions, in 4to. 1554. Be- sides these works, Reinhold was author of several others, which were never published. REINS, in Anatomy, the kidney's : in Horsemanship, long leathers fastened to the bit of the bridle, by which the horse is kept in subjection. REINSURANCE, in Commerce, a contract by which the first insurer relieves himself from the risks he had undertaken, and devolves them upon other underwriters, called re-insurers. REITERATION, the art of repeating a thing, or doing it a second time. REJOINDER, in Law, is the defendant’s answer to the plain- tiff’s replication or reply. . REJOINTING, in Architecture, the filling up of joints of the stone in old buildings, when worn by time, and the action of the elements. RELAPSE, in Medicine, the return of a disease when its virulence appeared to have been subdued, and the patient was regaining health. RELATION, in Philosophy, the mutual respect of two things, or what each is in regard to the other. Hence, relation may be moral, physical, or ideal; but some comparison or affinity is always implied in that which has only a relative existence. RELATION, in Kindred, denotes degrees of consanguinity. In Grammar, relation is the correspondence which words have with one another in construction. In Logic, it is an accident of substance, accounted one of the ten categories, or predica- In entS. RelATION, in Mathematics, is the same as RATIo, though we sometimes use it in a more general sense, indicating any dependence of one quantity upon another. RELAXATION, in Law. See Release. RELAY, a fresh equipage, horse, &c. sent before, or ap- pointed to be ready for a traveller on his arrival, to make the greater expedition in his journey. RELEASE, in Law, is an instrument in writing, by which estates, rights, titles, entries, actions, and other things, are ex- tinguished and discharged ; and sometimes transferred, abridg- ed, or enlarged : and in general, it is to signify a person’s giving up or discharging the right or action he has, or claims to have, against another, or his lands, &c. A release may be either in fact or in law; a release in fact is where it is expressly declared by the very words, as the act and deed of the party; and a release in law, is that which acquits by way of consequence, as where a female creditor takes the debtor to be her husband. RELEGATION, a kind of exile or banishment, by which an obnoxious person is commanded to retire to a certain place prescribed, and to remain until recalled or removed. RELICS, in the Romish church, are the remains of some body, clothes, or furniture, said to have belonged to a saint or martyr, devoutly preserved in honour of his memory, and car- ried in procession, kissed, and venerated. To these relics superstition has attached miraculous powers, and in this mum- mery that church has carried on a profitable trade for many centuries. ReLICT, in Law. See WIDow. - RELIEF, in Law, a certain sum of money which the tenant holding by knight's service, grand sergeantry, or other tenure, and being at full age at the death of his ancestor, paid to his lord at his entrance. - * RELIEVE, in Military language, is to take the place of another. - RELIEVE, in Chancery, denotes an order sued out for the dissolving of contracts, and other acts done, on account of their being unreasonable, prejudicial, or grievous. RELIEVING TAckles, two strong tackles, furnished each with guys and pendants, which, passing under the ship's bot- tom to the opposite side, are attached to the lower gun-ports; the tackles being hooked to the wharf or pontoon, by which the vessel is careened. They are used to prevent a ship from overturning on the careen, and to assist in bringing her upright after that operation is finished. Relieving Tackles, are also those which are occasionally hooked to the tiller in bad wea- ther or in action, when the wheel or tiller-rope is broken or shot away. Relieving Tackle, is also a name sometimes given to the train-tackle of a gun carriage. RELIEVO, or Relief, are terms applied to that mode of working in sculpture by which figures are made to project from the ground or body on which they are formed, and to which they remain attached. The same term is used, whether the figure is cut with the chisel, modelled in clay, or cut in metal or plaister. There are three kinds of relievo : Alto-relievo, or high relief, when the ſigures are so prominent from the ground that merely a small part of them remains attached to it. Mez- zo-relievo, or half relief, when one half of the figure rises from the ground, in such a manner that the figure appears divided by it. Basso-relievo, or bas-relief (low relief), when the work is raised but little from the ground, as in medals, and generally in friezes and other ornamented parts of buildings. Bas-relief is the comprehensive term by which all works in relievo are denominated indiscriminately. See Sculpture. RELIGION, is that worship or homage which is due to God considered as Creator and Preserver, and, with Christians, as Redeemer of the world. The foundation of all religion is, that there is a God, and that for his infinite perfections and innu- merable favours he requires some acknowledgment and ser- vice from his creatures. Hence religion necessarily supposes some intercourse between God and Man. Religion has been divided into two branches, natural and revealed. The existence of the former has been disputed, and the latter has been sub- ject to an endless diversity of interpretations. The thirty-nine articles of the established church of England are presumed to include the essentials of Christianity, and seditious words spo- ken in derogation of its truth are indictable as tending to a breach of the peace. 1 Haw. 7. RELIQUA, in Natural History, a term used to express the fossil remains of various animal, vegetable, and other sub- stances, ſound in a state of petrifaction, in different parts of the earth. Mr. Martin divides them into five classes, namely, fos- sil remains of animals or plants, earths, salts, inflammable substances, and metallic substances. Of these, the history is both curious and interesting, { & RELIQUAE, in Antiquity, the ashes and bones of the dead, which remain after the body had been burnt. These were carefully gathered up, and put into urns, and afterwards deposited in tombs. RELIQUARY, a shrine or casket in which the relics of saints are kept. R. E. N. R E P 883 DICTIONARY of MECHANICAL SCIENCE. RELL, the English name of the white-bellied mouse, with a blackish back and a long tail. - REMAINDER, that which arises by subtracting one quantity. from another. - - - ReMAINoer, in Law, is an estate limited in lands, tene- ments, or rents, to be enjoyed after the expiration of another particular estate. As if a man seised in fee-simple grant lands to one for twenty years, and, after the determination of the said term, then to another, and his heirs for ever; here the for- mer is tenant in years, remainder to the latter in fee. Both interests are, in fact, only one estate; the present term of years, and the remainder afterwards, when added together, being equal only to one estate in fee. When the remain- der is limited in a will, it is sometimes called an executory devise. This is not strictly a remainder, but something in nature of a remainder, which, though informal and bad, as such, is held good as an executory devise. The doctrine of remainders is very abstruse, chiefly from the difficulty of ascer- taining from the form of the deed or will by which it is created, whether or not the remainder is contingent, and liable to be defeated. Where, a remainder is limited after an estate tail, the tenant in tail can at all times, by suffering a recovery, defeat the remainder, and get possession of the fee. This is called docking the entail, and it is allowed for the purpose of preventing limitations in perpetuity. For, otherwise, men of large landed estates would be enabled to tie up the inheritance so strictly by will, that in a few years all the landed property in the kingdom would be vested for ever in certain families, and that circula- tion of wealth, which is the great spur to industry, would be wholly at an end. . REMANCIPATION was a form of divorce among the Romans, which was connected with some curious formalities. REMEDY, in Law, is the action or means given by law for the recovery of any supposed right. REMEDY, in Medicine, is any physical agent by which a disease may be alleviated or cured. JREMEMBRANCERS, anciently called clerks of the remem- brance, certain officers in the exchequer, whereof three are dis- tinguished by the names of the king's remembrancer, the lord treasurer's remembrancer, and remembrancer of the first fruits. REMINISCENCE, is that power of the mind by which it recals things which had been forgotten. In this respect it differs from memory with uninterrupted remembrance, while reminisiscence allows intervals of forgetfulness. The ancient Platonists were of opinion, that all learning, knowledge, and invention, consisted in the recollection of notices which had been in the soul prior to its union with the body. t REMISSION, in Law, is the pardon of a crime, In Medi- cine, it is the abatement of a disorder, which returns again after an interval. In Physick, it is the diminution of the power or efficacy of any quality. *. REMIT, in Commerce. To remit a sum of money, bill, or the like, is to send the sum of money, &c. REMITTER, in Law, is where one that has a right to Jands, but is out of possession, has afterwards the freehold cast upon him by some subsequent defective title, and enters by virtue of that title. . * * REMONSTRANCE, an expostulation, or humble supplica- tion, presented to the king, or other superior, praying him to reflect on the inconveniences of specific edicts or measures. It also implies a gentle reproof, but touched in a delicate manner. REMONSTRANTS, a title given to the Arminians, in conse- quence of their remonstrance in 1610, to the states of Holland, against the synod of Dort, in which their principles were con- demned. - * REMOVER, in Law, is where a suit is removed or taken out of one court into another; and is the opposite of remanding a ...; or sending it back into the same court whence it was first called. RENCOUNTER, the encounter of two small bodies de- tached from the main army; also a combat between two indi- viduals, distinct from a duel, being without premeditation. RENDER, in Law, a term used in the levying of a fine. RENDERING, is usually expressed of a complicated tackle, laniard, or lashing, when the effect of the power applied is com: municated with facility to all the parts without being inter- rupted. It is therefore used in contradistinction to jamming or sticking fast. - RENDEZVOUS, the port or place of destination, where the several ships of a fleet or squadron are appointed to join com- pany, or to rejoin in case of separation. ReNDEzvous, a name given to any house where a press- gang resides, and volunteers are invited to enter into the navy. Also, a place appointed to meet in, at a certain day and hour. RENDLING CURD, in rural economy, a term used to signify the broken curd in cheese-making. . RENEGATE, a person wha has apostatized from the Chris- tian faith, and embraced somé other mode of religion, particu- larly Mahometanism. RENITENCY, in Philosophy, is that force in solid bodies, by which they resist the impulse of other bodies, or re-act as much as they are acted upon. - RENNET, in rural economy, a term applied to the coagulum for making cheese. It is prepared from the bag, maw, or stomach of the young calf, by a salt pickle. The preparations are various; but in the making of cheese much depends upon having a good sweet rennet. - RENT, is a certain profit issuing yearly out of lands and te- nements corporeal. There are at common law three kinds of rents; rent service, rent charge, and rent seck, or rack rent: Rent ser- vice is where the tenant holds his land of his lord by fealty and certain rent ; or by homage, fealty, and certaiu rent; or by other service and certain rent; and it is called a rent service because it has some corporeal service incident to it, which at least is fealty. Rent charge is so called because the land for payment of it is charged with a distress. Rent seek, or rack rent, is where the land is granted without any clause of distress for the same. The time for payment of rent, and consequently for a demand, is such a convenient time before the sun-setting of the last day, as will be sufficient to have the money counted; but if the tenant meets the lessor on the land at any time of the last day of payment, and tenders the rent, that is sufficient ten- der, because the money is to be paid indefinitely on that day, and therefore tenders on that day is sufficient. RENTAL, a roll in which the rents of a manor are entered, and from which they are collected, and the amount is ascer- tained. REPAIR, the operation of repairing any injuries, or supply- ing any deficiencies, which a ship may suffer from age, battle, storm, accident, &c. The repair is necessarily greater or smaller in proportion to the loss which the vessel has sus- tained. Accordingly a suitable number of the timbers, beams, or planks, or a sufficient part of either, are removed, and new pieces fixed in their places. The whole is completed by bream- ing, caulking, and paying the body with a new composition of stuff. See BREAMING, &c. - REPARTEE, a ready smart reply, especially in matters of wit, humour, or raillery. - REPEALING, in Law, the revoking or annulling of any statute, deed, &c.; but no act of parliament can be repealed in the same session in which it was made. REPEATING Mechanism, in Horology, is a mechanical con- trivance, by which a clock or watch is made to repeat the hours and quarters of existing time, so that a person in the dark, or in bed, may know the time by night, as well as by day. Bar- low, a clock-maker of London, in 1676, had the lionour of this invention. • * REPEAT SIGNALs, To, is to make the same signal with the . admiral, in order to its being more readily distinguished at a distance, or through smoke, &c. & To Repeat a Signal, some- times implies to repeat a signal over again, on account of its not having been attended to the first time. The repeat is usually accompanied with a gun. REPEATING-SHIP, is a vessel (usually a frigate) ap- pointed to attend each admiral in a fleet, and to repeat every signal he makes, with which she immediately sails the whole length of the fleet or squadron, if the signal is general, or to the ship for which it is intended, if particular, and then returns to her station near the admiral's ship. REPELLENT ME Dic1 Nes, are those which prevent such an afflux of fluids to any part as would excite tumor or inflamma- tion, or to diminish that already produced. 884 R. E. P. R E P DICTIONARY OF MECHANICAL SCIENCE - REPELLING Power, in Physics, is a power or faculty residing in, and exerted by, the minute particles of natural bodies, by which they mutually recede from each other. REPERCUSSION. See RefLECTION. - . § REPERTORY, a place in which things are orderly disposed, so as easily to be found when wanted. Hence, indices of books are repertories. - - REPETEND, in Arithmetic, denotes that part of an infinite decimal which is continually repeated ad infinitum, and is other- wise called a circulate. . . . - REPETITION, in Music, denotes a reiterating or playing over again the same part of a composition, whether it is a whole strain, part of a strain, or double strain, &c. Repetition, in Rhetoric, a figure which gracefully and em- phatically repeats either the same word, or the same sense in different words. - REPLANTING, in Gardening, the act of planting trees, shrubs, or flowers, a second time. Many plants require this process, to prevent them from degenerating. REPLEADER. Whenever a repleader is granted, the plead- ings must begin de novo at that stage of them, whether it is the plea, replication, rejoinder, or whatever else, wherein there appears to have been the first default or deviation from the regular course. * - REPLEGIARE, a writ brought by one whose cattle are distrained and put in pound by another, upon security given the sheriff to pursue or answer the action at law, against the distrainer. - REPLETION, in the Canon Law, is where the revenue of a benefice is sufficient to fill or occupy the whole right of the graduate who holds it. Where there is repletion, the party can demand no more by virtue of his degrees. - REPLEVIN, in Law, is a writ by him who has cattle or other goods distrained by another, for any cause. If he wishes to dispute the propriety of the distress, he sues this writ, and upon putting in surety to the sheriff, that upon delivery of the thing distrained, he will prosecute the action against the dis- trainer, the cattle or goods are delivered back, and are said to be replevied. In this writ, or action, both the plaintiff and de- fendant are called actors; the one, that is the plaintiff suing for damages, and the defendant, who is also called avowant, to have a ret rn of the goods or cattle. If the replevin be determined for the plaintiff, namely, that the distress was wrongfully taken, he has already got his goods back into his own possession, and shall keep them, and recover damages. But if the defendant prevail, by the default or non-suit of the plaintiff, then he shall have a writ de returno habendo, or to have a return, whereby the chattels which were distrained and then replevied, are returned again into his custody, to be sold, or otherwise disposed of, as if no replevin had been made. If the distress were for damage feasant, that is, for cattle breaking through fences, and coming upon the land of the party, the distrainer may keep the goods so returned, until tender shall be made of sufficient amends. REPLICATION, in Logic, the assuming or using the same term twice in the same proposition. Replication, an exception or answer of the plaintiff in a suit to the defendant’s plea ; and is also that which the com- plainant replies to the defendant's answer in chancery, &c. REPORT, in Law, is a public relation of cases judiciously argued, debated, resolved, or adjudged, in any of the king's courts of justice, with the causes and reasons of the same, as delivered by the judges. REPOSE, in Painting, Gertain masses or large assemblages of light and shade, which being well conducted, prevent the confusion of objects and figures, by engaging and fixing the eye, so that it cannot attend to the other parts of the painting for some time; and thus leading it to consider the several groups, gradually proceeding from stage to stage. Repose, Angle of, an angle of 35°. - REPOSITORY, a storehouse, or place where things are laid up or kept. REPRIMAND, a sharp authoritative reproof. . In military discipline a reprimand is deemed a severe punishment. REPRESENTATION. There is a heir by representation, where the father dies in the life of the grandfather, leaving a son, who shall inherit the grandfather's estate, before the father’s brother, &c. REPRESENTATIVE, one who personates or supplies the place of another, and is invested with his right and authority. The Commons are presumed to be the representatives of the people in parliament. - * * REPRIEVE, to suspend a prisoner from the execution and proceeding of the law at the time. • . REPRISAL, or RePRise, is the retaking a vessel from the enemy soon after the first capture, or at least before she has arrived in any neutral or hostile port. If a vessel thus retaken, has been twenty-four hours in the possession of the enemy, she is deemed a lawful prize; but if retaken within that time, she is to be wholly restored to the owner, upon his allowing one- third of her value for salvage to the recaptors. Also, if a ves- sel has, from any cause, been abandoned by the enemy before he has taken her into any port, she is to be restored to the original proprietor. - REPRISE, or Reprize, at sea, is a merchant ship which, after its being taken by a corsair, privateer, or other enemy, is retaken by the opposite party. If a vessel thus retaken has been twenty-four hours in the hands of the enemy, it is deemed a lawful prize; but if it be retaken within that time, it is to be restored to the proprietors, with every thing therein, upon his allowing one-third to the vessel who made the reprise. Also, if the reprise has been abandoned by the enemy, either in a tem- pest or any other cause, before it has been led into any port, it is to be restored to the proprietor. - REPRODUCTION, is usually understood to mean the res. toration of a thing before existing, and since destroyed. It is very well known that trees and plants may be raised from slips and cuttings; and some late observations have shewn that there are some animals which have the same property. The polype (See HYDRA) was the first instance we had of this kind; but we had scarcely time to wonder at the discovery M. Trembley had made, when M. Bonett discovered the same property in a spe- cies of water-worm. Among the plants which may be raised from cuttings, there are some which seem to possess this quality in so eminent a degree, that the smallest portion of them will become a complete tree again. A twig of willow, poplar, and , many other trees, being planted in the earth, takes root, and becomes a tree, every branch of which will in the same manner produce other trees. The case is the same with these worms; they are cut to pieces, and each separate piece becomes a perfect animal : and, each of these may be again cut into a number of pieces, each of which will in the same manner produce an animal. The reproductions of several parts of lobsters, crabs, &c. is one of the greatest curiosities in natural history. It seems indeed inconsistent with the modern system of generation, which supposes the animal to be wholly formed in the egg, that, in lieu of an organical part of an animal cut off, another should arise perfectly it: the fact, however, is too well attested to be denied. - - REPTILIA, in Natural History, an order of Amphibia, the character of which is, that they breathe through the mouth, have feet, and flat naked ears without auricles. There are five genera; viz. Draco, Siren, Lacerta, Tertudo, Rana. - . REPUBLIC, a popular state or government; or a nation where the body or only a part of the people have the govern- ment in their own hands. When the supreme power is pos- sessed by all the body, it is called a democracy; when it is lodg- ed in a part of the people, it is called an aristocracy. REPULSION, in Physics, that property in bodies, whereby, if they are placed just beyond the spheres of each other’s attrac- tion of cohesion, they mutually recede and fly off. . Thus, if any oily substance lighter than water, be placed upon its surface, or if a piece of iron be laid upon mercury, the surface of the fluid will be depressed about the body which is laid on it: this de- pression is manifestly occasioned by a repelling power in the bodies, which prevents the approach of the fluid towards theni. But it is possible, in some cases, to press or force the repelling bodies into the sphere of each other’s attraction; and then they will mutually tend toward each other, as when we mix oil and water till they are incorporated. Dr. Knight defines repulsion to be that cause which makes bodies mutually endeavour to recede from each other with different forces at different times; R. E. S R E s DICTIONARY OF MECHANICAL SCIENCE. 885 and that such a cause exists in nature, he thinks evident for the [ following reasons: 1. Because all bodies are electrical, or capa- ble of being made so ; and it is well known that electrical bo- dies both attract and repel. 2. Both attraction and repulsion are very conspicuous in all magnetical bodies. 3. Sir Isaac Newton has shewn from experience, that the surface of two convex glasses repel each other. 4. The same great philoso- pher has explained the elasticity of the air, by supposing its particles mutually to repel each other. 5. The particles of light are in part at least repelled from the surfaces of all bodies. 6. Lastly, it seems highly probable that the particles of light mu- tually repel each other, as well as the particles of air. Dr. Knight also ascribes the cause of repulsion, as well as that of attraction, to the immediate effect of God’s will ; and as attrac- tion and repulsion are contraries, and consequently cannot at the same time belong to the same substance, the doctor supposes there are in nature two kinds of matter, one attracting, the other repelling; and that those particles of matter which repel each other, are subject to the general law of attraction in respect of other matter. A repellent matter being thus supposed, equally dispersed through the universe; he attempts to account for many natural phenomena by this means. He thinks light con- sists of this repellent matter put into violent vibrations by the repellent corpuscles which compose the atmosphere of the sun and stars; and that, therefore, we have no reason to believe they are gulfs of fire, but, like the rest of the heavenly bodies, inhabitable worlds. From the same principles he attempts to ex- plain the mature of fire and heat, the various phenomena of the magnet, and the cause of the variation of the needle; and, indeed, it is difficult, if not impossible, by the doctrine of attrac- tion alone, to account for all the phenomena observable in expe- riments made with magnets, which may be solved by admitting this doctrine of a repellent fluid ; but whether it will be suffi- cient to account for all the particular phenomena of nature, which is the proper test of an hypothesis, time and experience alone must determine. The doctor also endeavours to shew that the attractions of cohesion, gravity, and magnetism, are the same, and that by those two active principles, viz. attraction and repulsion, all the phenomena of nature may be explained; but as his ingenious treatise on the subject is laid down in a series of propositions connected together, it would be impossi- ble to do justice to his arguments without transcribing the whole : we shall therefore refer the curious reader to the book itself. According to Gravesand and others, when light is re- flected from a polished spherical surface, the particles of light do not strike upon the solid parts, and so rebound from them ; but are repelled from the surface at a small distance before they touch it, by a power extended over such polished surface. REQUESTS, Court of, an ancient court of equity instituted about the nineteenth year of Henry VII. REQUIEM, a mass sung in the Romish church for the rest of the soul of the deceased. RESCRIPT, an answer delivered by an emperor or pope, when consulted by particular persons, on some difficult ques- tion, or point of law, to serve as a decision thereof. RESCUE, or Resco Us, is the forcibly freeing another from an arrest, or some legal commitment; which being a high offence, subjects the offender not only to an action at the suit of the party injured, but likewise to fine and imprisonment at the suit of the king. - - RESERVE, BoDY of, or corps de reserve, in Military Affairs, the third or last line of an army drawn up for battle. RESERVOIR, a large pond or enclosure of water, artificially made, in order to collect and retain it for the use of canals, mills, and occasional streams. Reservoirs are applied to various other purposes in agriculture and domestic economy. RESIDENCE, in an ecclesiastical sense, is the continuance of a parson or vicar on his benefice. - - RESIDUAL ANALYsis, a branch of analysis invented by Landen, and applied by him to the solution of those prob- lems which are more generally solved by the doctrine of flux- ions. This method was called the residual analysis, because in all cases where it is made use of, the conclusions are obtain- ed by means of residual quantities. In this analysis a geome- trical or physical problem is reduced to another purely alge- braical; and the solution is then obtained without any suppo- sition of motion, and without considering quantities as composed of infinitely small particles. The residual analysis proceeds by taking the difference of the same function of a variable quantity . in two different states of that quantity, and expressing the rela- tion of this difference to the difference between the two states of the said variable quantity itself. This relation being first expressed generally, is then considered in the case when the difference of the two states of the variable quantity is = 0. RESIDUAL Quantity, in Algebra, is a binomial connected by the sign — ; thus a - b; a -º/b, &c. are residual quantities. RESIDUAL F1GURe, in Geometry, the figure remaining after subtracting a lesser from a greater. RESIDUE, or ResiduuM, that which is left after taking the part of any thing away, being much the same as remainder, the former being applied to quantity in the same sense as the latter is to number. - - - RESIGNATION, in the Canon Law, the surrendering a be- nefice into the hands of the collator, or bishop. RESIGNATION, or Resignee, in Law, the person to whom the thing is resigned. - - - RESIN. The name resin is used to denote solid inflamma- ble substances, of vegetable origin, soluble in alcohol, usually affording much soot by their combustion. They are likewise soluble in oils, but not at all in water, and are more or less acted upon by the alkalis. All the resins appear to be nothing else but volatile oils, rendered concrete by their combination with oxygen. Resin, analyzed by M. M. Gay Lussac and The- nard, was found to consist of: Carbon, 75.944; hydrogen, 10719; water, 15:156; oxygen 13:337; hydrogen in excess, 8-9. The resin of fir is known by the name of rosin. Its properties are well known. Its specific gravity is 1072. It melts readily, burns with a yellow light, throwing off much smoke. Resin is insoluble in water either hot or cold, but very soluble in alcohol. RESISTANCE, of the fibres of solid bodies, is more properly called cohesion. - - Resist ANCE, or Resisting Force, in Physics, any power which acts in opposition to another, so as to destroy or diminish its effect. Resistances are of various kinds, arising from the nature and properties of the resisting bodies, the circumstance in which they are placed, and the laws by which they are govern- ed. These may be divided into the following cases: 1. The resistance between the surfaces of contiguous solid bodies, generally denominated friction. See FR1ction and ADH ESION. 2. The resistance between the contiguous particles of the same body, whether fluid or solid; for the laws of which see Cohesio N and St ReNGTH. - - - - 3. The resistance that solid bodies oppose to penetration; for which see PENETRATION and RePULslo N. 4. The resistance of elastic and non-elastic fluids to the mo- tion of bodies moving in them. The principles of which we will endeavour to illustrate in the present article. The resist- ance which a body experiences from the fluid medium through which it is impelled, depends on the velocity, form, and magni- tude of the body, and on the inertia and tenacity of the fluid. For fluids resist the motion of bodies through them, 1. By the inertia of their particles. - 2. By their tenacity, or the adhesion of their particles. 3. By the friction of the body against the particles of the fluid. . .." . In perfect fluids, the latter causes of resistance are very in- considerable, and therefore are not commonly considered. But the first is always very considerable, and obtains equally in the most perfect and in the most imperfect fluids. In what follows, and in all cases of a similar description, it will be necessary to distinguish between resistance and retardation ; the former being the quantity of motion, and the latter the quantity of ve- locity which is lost; therefore the retardations are as the resist- ances applied to the quantity of matter, and in the same body they have always the same constant ratio to each other. In fluids of uniform tenacity, the resistance from the cohesion of its particles is as the velocity with which the body moves. For since the cohesion of the particles is constantly the same in the same space, whatever may be the velocity, the resistance from this cohesion will be as the space described in a given time, | that is, as the velocity. In a fluid whose parts yield easily 10 Q 886 R. E. T R F. T DICTIONARY OF MECHANICAL SCIENCE. without disturbing each other's motions, and which flows in behind as fast as a plane body moves forward, the resistance will be as the density of the fluid; for in this case the pressure on every part of the body is the same as if the body were at rest, RºSOLUTION, in Chemistry, &c, the reduction of a mix- ed body into its component parts, or first principles, by a pro- per analysis. - - - - Resolution, in a general sense, denotes the dividing or separating any compound quantity or thing into its original component parts. - - Resolution of Equations, in Algebra, is the determination of the values of the unknown letters or quantities of which the equation is composed; in order to which, it is necessary first to exterminate or climinate all the unknown quantities but one of the equation, and then the value of the remaining quantity is to be found by the proper rules for this purpose, viz. by the rules given for simple, quadratic, cubic, or biquadratic equa- tions, according to which of these it may belong; or by the general method of approximation; for which see the respective articles. - Resolution of Motions and Forces. of Forces. - RESPIRATION, is the act of receiving a portion of air into the lungs, and again emitting it. charged with a portion of carbon which it emits in the lungs, and this carbon uniting with the oxygen received in the lungs, forms carbonic acid gas, and is emitted, as is also the nitrogen or azote. The volume of carbonic acid discharged is exactly See PARALLELoGRAM equal in bulk to the oxygen which has disappeared, and it is . hence supposed that no oxygen is absorbed by the lungs; but other philosophers have been of a contrary opinion, and have sup- posed that the change of the colour of purple of the venous blood into red, in the arterial blood, which takes place on passing through the lungs, was attributable to the absorption of oxygen, whilst, on the other hand, this has been attributed solely to the discharge of the carbon. An ordinary sized man consumes about 46,000 cubic inches of oxygen per day, and makes 20 respirations in a minute. The quantity of carbonic acid formed during respiration is diminished after swallowing intoxicating liquors, or under a course of mercury, nitric acid, or vegetable diet. RESPITE, in LSw, &c. a delay, forbearance, or prolongation of time, granted to any one for the payment of a debt. In cri- minal cases, it is the suspension of a sentence, as to the time of its being executed. In knight service, it is the dispensing with the homage of a vassal, on certain conditions, and during a given time. . . REST, in Physics, the continuance of a body in the same place, either absolutely or relatively, viz. its continuance in the same part of absolute space, or in the same part of relative space; and is hence denominated absolute or relative rest. It is, however, highly probable, that in its most extensive sense there is no such thing as absolute rest in the whole creation, at least we know of nothing in such a state. RESTING GROUND, the omission of crops for a given period, that the soil may recover its primitive fertility, which constant tillage tends to impoverish. RESTITUTION, in Physics, the returning of elastic bodies, forcibly bent, to their natural state. In a moral sense, restitu- tion, reinstates a person in his fºhts, or restores something that had been unjustly taken from him. In law, it is a return- ing of stolen goods. s RESULTANT, in Mechanics, is used to denote that single force, or the line represent the quantity and direction of that single force, which is equivalent to two or more forces whose quantities and directions are given. - RETAINER, in Law, a servant who does not continually dwell in the house of his master, but only attends upon special occasions. .. RETAINING Fee, the first fee given to a sergeant or coun- sellor at law, in order to make him sure, and prevent his plead- ing on the contrary side. RETALIATION, the act of returning like for like. It is ex- cited by aggression, and frequeutly leads to civil wars. RETARDATION, any force tending to diminish the velocity of moving bodies. . . . - r The blood of the veins is | } | h RetARDAtion may arise either from the effect of resistance, or from the action of gravity. For that which arises from the former, and for the distinction between resistance and retarda- tion, see Resist ANC E. - RETARDATION, from Gravity, is peculiar to bodies projected upwards, which have their velocities, diminished, by precisely the same laws as falling bodies have: theirs accelerated. Thus, if a body be projected perpendicularly upwards, with a velocity which would, independently of gravity, cause it to ascend a feet per second; it will, in consequence of the action of gravity, have its velocity so diminished, that, at the end of the first second, it will be only (a—32) feet, or at the end of the second it will be only (a—64) feet, &c. Hence, to find the greatest height to which a body will ascend when projected perpendicu- larly upwards with any given velocity, the time of ascent, &c. it is only necessary to find the space through which a body must fall to generate that velocity, and the time it would be in descending through that space, which will be precisely the same as the height through which it will ascend, and the time of its ascent. See AcceleRATION. - RETCHING, in Sickness, an effort or endeavour to vomit. RETEN EGE, in the Materia Medica, a name used to express the common resin of the pine or fir tree, and sometimes com- mon black pitch. RETENTION, is defined, by Locke, to be a faculty of the mind, whereby it keeps or retains those simple ideas it has once received by sensation or reflection. RETENTION, is also used, in medicine, &c. for the sate of contraction in the solids or vascular parts of the body, which makes them hold fast their proper contents. RETI, in Hindoo Mythology, is a personification of affection, and the fabled consort of Kama the god of love. RETICULA, or RETICULE, the name of an instrument form- erly employed for measuring the number of digits eclipsed in either luminary ; its construction depends on nearly the same principles as that of the MicroM ETER. RETINA, in Anatomy, a membrane of the eye, formed by an expansion of the optic nerve, and constituting the imme- diate organ of vision, See EY e. RETINASPHALTUM, in Mineralogy, a name given to an inflammable kind of resinous substance accompanying Bovey coal. On the first application of heat, it melts and smokes, and then burns with a bright flame. RETINUE, the attendants or followers of a prince or person of quality, chiefly-on a journey. RETIRED List, a list on the marine establishment, on which superannuated officers are placed. Officers on the retired list of the East India service, have several advantages over others. RETORT, in Chemistry, is a kind of round-bellied vessel, made of earth, glass, or metal, having a crooked neck or beak to which the recipient is fastened. Retorts are of essential service in distillations, and most frequently for those which require a degree of heat superior to that of boiling water. RETRAXIT, in Law, is where the plaintiff comes into court in person, either alone or with the defendant, and declares he will proceed no further in his action. When this is done the same action can never be renewed. RETREAT, in Gardening, is an erection or arbour, a nook or recess, formed either for pleasure or convenience. In its form- ation, utility and beauty should go hand in hand. Ret ReAT, the order or disposition in which a fleet or squa- dron declines engagement, or flies from a pursuing enemy. RETREAT, in War, is the retiring or retrograde motion of an army from its former position. The skill of a commander is generally more conspicuous in his retreats than in his advances and engagements. The retreat of the ten thousand Greeks under Xenophon has been the subject of universal admiration. The most remarkable retreats in modern times have been that of Moreau in 1796, through Swabia; that of Macdonald in Italy; and that of Sir John Moore in Spain, in 1809-1810. RETRENCHMENT, in the art of War, any kind of work, raised to cover a post, and fortify it against the enemy. RETROACTIVE, in Law, that which has an operation or influence on time and transactions that are past. RETROGRADATION, or Retrog Ression, in Astronomy, is an apparent motion of the planets, by which they seem to R. E. W. R E V 887 DICTIONARY OF MECHANICAL SCIENCE. move backward in the ecliptic, or in antecedentia, or contrary to the order of the signs. When a planet moves in consequentia, or according to the order of the signs Aries, Taurus, Gemini, &c. it is said to be direct. When it appears for a few succes- sive days in the same place or point of the heavens, it is said to be stationary. And when it goes in antecedentia, or contrary to the order of the signs, it is said to be retrograde. - Both the superior and inferior planets are subject to this apparent irregularity in their motions; but it arises from dif- ferent causes, as may be illustrated as follows:—Let C D cd represent the orbit of the earth, and A B a b that of any inferior planet, as Venus; now when the earth is at c, and Veuws at A, the former being moving towards d with a less velocity than the latter is towards B, it is obvious, that the apparent motion of Venus, as re- ferred to the beavens MN, will be from . . M towards N, or according to the order of the signs. But if, when the Earth is at c, Venus is at a, then her apparent place in the heavens will be at N. ; and when the Earth is arrived at d, Venus will have come to b, and her apparent place in the heavens will be at M, and conse- quently during this time she will appear to be moving in the heavens from N to M, viz. contrary to her former motion, which motion being in antecedentia, or contrary to the order of the signs, is then said to be retrograde. Whence it appears that when an inferior planet is in, or nearly in its superior conjunc- 272.27 tion, its apparent motion is direct, but when in its inferior con- junction, its apparent motion is retrograde, and for a few days between these two she has no apparent motion, and is therefore said to be stationary. . . . . . - With regard to the superior planets, it is obvious that their re- trogradation must happen when they are in opposition ; thus, if we now suppose A B a b to be the orbit of the earth, and C D cd that of Saturn, and suppose that when the latter is at C, the former is at A, then the apparent place of Saturn in the hea- vens will be at n ; but the motion of the Earth exceeding that of Saturn, when we are arrived at B, he will only be got to D, and his apparent place will be at m ; and therefore during this tnterval his apparent motion will be retrograde. Whereas it is ob- vious that had the earth been at a, instead of being at A, as we have supposed above, that is, if Saturn had been in con- junction, its apparent motion in the heavens must have been contrary to the former, or in consequentia, or according to the order of the signs ; and for a time between these two motions he must necessarily bave appeared stationary, as is obvious without any particular illustration. The periods of retrograda- dation of the several planets are not aways the same, but at a mean they are nearly as follows:–Saturn 140 days, Jupiter 120 days, Mars 73 days, Venus 42 days, and Mercury 22 days. RETROCESSION of the Equinoaces. See PRecession. REVE, Reeve, or Greve, the bailiff of a franchise, or manor, thus called, especially in the west of England. REVEILLE, a beat of drum about break of day, to give no- tice that it is time for the soldiers to arise, and that the sentries are to forbear challenging. - REWELS, entertainments of dancing, masking, acting come- dies, farces,’ &c. . . . REVENUE, PUPLic, the portion of the general income of a state, which is appropriated to the payinent of national ex- penses. The ordinary revenue of the early kings of England consisted of the following branches: - - 1. Rents and profits of the crown-lands. 2. Profits from military tenures. As a great part of the lands in England were subject to knight-service, the profits incident to this tenure were very great, besides the extraordinary con- tributions to which they were liable, for making the king's son a knight, and for marrying his eldest daughter. 3. The custody of the lay revenues, with the lands and tene- ments of bishoprics during their vacancy. - 4. First-fruits, and tenths of all spiritual preferments. These revenues are now. vested in trustees for ever, as a fund for the augmentation of poor livings, and form what is usually called Queen Ann's Bounty. - - .5. Purveyance and pre-emption, or a right of buying up pro- visions and other necessaries, for the use of the royal house- hold, at an appraised valuation, in preference to all other per- Sons, and even without the consent of the owner; also of forci- bly impressing carriages and horses for the king's use º set- tled price, The purveyors greatly abused their authority, and were of little advantage to the crown; Charles II. therefore at his restoration, agreed to resign this prerogative, with the mili- tary tenures; and the Parliament, in lieu thereof, settled on him and his successors for ever a tax on beer and ale, afterwards | commonly called the hereditary excise. ... 6. Fines and forfeitures of various descriptions; also fees to | the crown in a variety of legal matters. 7. The right to all shipwrecks; to treasure-trove; to royal fish, that is, whales and sturgeons, when thrown ashore, or | caught near the coast; to all mines of silver or gold; to waifs or goods stolen and thrown away by the thief in his flight; and estrays, or animals found wandering, and the owner unknown ; and to deodands, and forfeitures of lands and goods for offences. These rights, producing little profit, have since been mostly granted away to the lords of manors and other liberties. 8. Escheats of lands upon the defect of heirs to succeed to the inheritance, in which case they reverted to the king. 9. The custody of idiots and lunatics, the profits of whose lands were received by the king, an allowance being made to them for necessaries. 4. - From these sources, the produce of the remaining branches of which is now very insignificant, the kings of England derived the whole of their ordinary revenue, till commerce raised the pro- duce of the customs into importance, and the parliament ven- tured to grant the principal part of their produce to the king, for life. Upon extraordinary occasions, Henry II. and some of | his successors, had recourse chiefly to scutages, which were a composition of those who held knights’ fees, in lieu of the mili- tary service to which they were bound, as the king and the per- sons liable could agree: hydage and talliage were taxes of the same nature, upon other lands and upon other cities and boroughs. Tenths and fifteenths were originally the real tenth or fifteenth of all the moveables belonging to the subject; the amount was uncertain, being levied by new assessments on every fresh grant, till the 8th Edward III. when a new assess- ment was made and recorded in the exchequer, which was the real value at that period of every city, borough, and town in the kingdom, and by this the fifteenths were afterwards levied according to the specific sums therein stated, which were usu- ally raised in different places by a common rate on all the in- habitants. Subsidies were a grant introduced about the time of Richard II. and Henry IV. This mode of taxation fell into disuse during the civil wars in the reign of Charles I. when the parliament introduced weekly and monthly assessments, at a fixed sum upon each county, which was levied by a pound rate both upon land and personal estates. The commonwealth afterward introduced excise duties, and derived some profit from the establishment of the post office, both of which have been since improved into very productive sources of revenue. The various duties, now constituting the total public revenue of Great Britain, are arranged under the following heads: 1. The Custom, which consist of duties on goods imported, on goods exported, on goods garried coastways, and a tonnage duty. # 2. The Excise, which consists principally of duties on malt liquors of every kind, including the distillery; many other articles are, however, likewise included, as candles, leather, soap, starch, tea, . coffee, wine, tobacco, salt, glass, printed goods, and bricks and tiles. 3. Stamp Duties, laid on deeds and documents of almost every description. - 4. Land and Assessed Taxes. In 1799 a scheme was adopted for the redemption of the land tax, for which purpose an act was passed, making the tax perpetual; it was then offered for sale to the proprietors of the lands upon which it was charged, or, if they declined it, to any other persons who chose to be- come a purchaser. The consideration to be given in either case was not to be in money, but in the three per cent. stock: the object of the scheme being to absorb a large quantity of floating stock, and thus facilitate the raising of new loans. It 888 R E V R. E. W. DICTIONARY OF MECHANICAL SCIENCE. was estimated that this measure would transfer about eighty millions of stock to government, but the terms offered were by no means such as to induce a general approval of it, and the total amount of stock transferred for land-tax redeemed on the first qf February, 1808, was only 22,976,8291. 10s. 4d. of course a very considerable portion of the tax still remained unredeem- ed. The assessed taxes consist of the duties on houses, win- dows, servants, carriages, horses, and horse-dealers, dogs, hair powder, and armorial bearings. - 5. The Post Office. King James I. originally erected a post office for the conveyance of letters to foreign parts, previously to which an establishment of this kind had existed for the con- veyance of inland letters. . - - - - 6. Sixpence in the pound on pensions and salaries. 7. One shilling in the pound on pensions and salaries. 8. Hackney coaches. 9. Hawkers and pedlars. - - In addition to these several branches of the public revenue, there are some small branches of the old hereditary revenue still remaining. These consist chiefly of alternation fines, post fines, seizures of uncustomed and prohibited goods, compositions, profers and the crown lands, of which the last is by far the most important.—Watkins's Cyclopædia. REVERBERATION, in Physics, the act of a body repelling or reflecting another after its impinging on it. , Hence, echoes are occasioned by the reverberation of sounds from arched obstacles. In glass furnaces the flame reverbérates, or bends back again, to burn the matter on all sides. In Chemistry, reverberation denotes a circulation of flame, or its return from the top to the bottom of the furnace, when calcination is required. REVERENCE, in Ethics, is the veneration or high degree of respect which is paid to superior sanctity, by a conscious inferiority of moral worth. - REVERSE, of a medal, coin, &c. denotes the second or back side in opposition to the head or principal figure. REVERSED, in Heraldry, a thing turned backwards or up- side-down. - - - - REVERSION, a sum of money, estate, annuity, or any other kind of property, the possession of which is not to be obtained till after the expiration of a certain period of time, or till some event, as the failure of a life or lives has happened. The present value of such property depends greatly on the current interest of money, for if money produced only three per cent. interest, a person giving 1000l. for a reversionary estate relinquishes an annuity of 30l. but if he could make five per cent. interest of his money, he gives up an annuity of 50l. and consequently in the latter case he would expect a greater reversion than the former. The true value of a reversion therefore is that present sum which, if improved at a given rate of interest, would, at the period when the reversion comes into possession, amount to its then actual value. This, with respect to sums receivable at the end of a certain number of years, is easily found by the Table of INTEREST. Thus, if a person is entitled to 500l. at the end of ten years, and wishes to know its present worth : the value of one pound to be received at the end of this term, is, by the Table, 613913, which multiplied by 500, gives 326l. 19s. 1d. for Whe present value of the reversion. - REVERSION of SERies, in Algebra, is the method of find- jng the value of the root or unknown quantity, whose powers enter the terms of a finite or infinite series, by means of another series in which it does not enter. - REVERSING of Motions, Contrivances for. We shall here mention some methods of reversing motions after long inter- vals; as is the case of drawing up buckets from wells or mines, where no change of direction may be required for several minutes; or in different kinds of mill work, where the direction may not be changed for some hours. Contrivances to effect such reversion of motion are very numerous; but almost all of them may be reduced to two gene- ral methods; for the required change is generally produced either by making two equal pinions on one and the same axis, taken alternately into the teeth of those parts of a larger wheel which are nearly diametrically opposite; or, by means of an additional wheel, which may, as the practical mechanics term it, be thrown in and out of gear alternately. In many engines for drawing buckets out of mines that are moved by horses, the motion is frequently reversed by turning round the animal, and causing him to retrace his steps and draw the contrary way; but this is found very injurious to the horse, a circumstance which has frequently led to the adoption of other methods. In Emerson’s Mechanics, a simple contrivance is described, con- sisting merely of a horizontal face wheel, upon the same verti- cal shaft as the horse-pole is attached to, and two equal pinions upon the same axle as carries the drum or barrel on which the rope winds. The axle which carries the drum and pinions is fixed horizontally, a little above a diameter of the face wheel; and first one, and then the other, of the pinions is made to be driven by that wheel; thus, manifestly, reversing the motion as required. There are two methods of attaching these pinions to the axle, and making them to be acted upon by the face-wheel : in one of them, the pinions are fastened upon the axle, at a dis- tance from each other exceeding the diameter of the face wheel only three or four inches; then, the axle being moved horizon- tally through this small distance, brings first one and then the other pinion into contact with the wheel at opposite extremi- ties of a diameter, and thus changes the direction of the motion; but this method is attended with the disadvantage of having often to move a heavy weight with the horizontal axle, besides that there is much danger of breaking the teeth of the pinions and wheel when they first come to embrace each other. In the second method, the lanterns or pinions both turn constantly with the face wheel, but they play freely upon their common axle, except that they are stopped by a pin which fixes them; the application of such pin to first the one, and then the other, ef the lanterns, produces the alternating motion as proposed. M. Prony has two contrivances for reversing the motion in horse-whims, without changing that of the animal : in both of which, however, the general principle is the same as that adopted by Emerson. In the first, a horizontal wheel, toothed at its face, lay just above two vertical pinions, fixed on the opposite extremities of an axis of the length of its diameter. This wheel was so contrived as to incline a little from its hori- zontal position to either side at pleasure; so that on the one inclination, its teeth locked with those of one pinion, and re- ceded from the other; and on the other position, its operation on the pinions was reversed; by which, the axis of the pinions turned round first in one direction, and afterwards in the contrary. Prony, finding this method subject to some inconve- niences, contrived the following, which he esteems much supe- rior to it. A horizontal wheel, toothed at its face, and attached to a perpendicular arbor, (which gives, it motion,) turns two pinions, moveable on the same axis, which it meets at the oppo- site sides of its circumference: these pinions are not attached to the axis, but turn round freely upon it: the intermediate part of the axis is square, and has, adjoining to each pinion, boxes which slide back and forwards on it, each of which support a faced wheel, with strong serrated teeth; the serration being in a different direction on the opposite wheels: the boxes are connected by two iron bars, so as to change their places by one movement; to the pinions there are also serrated faced wheels attached, so as to lock on those opposite to them on the sliding boxes. From this construction it follows, that when the boxes are slidden to one extremity of the axis, the pinion at that side will be connected with the axle, and communicate its motion to it in one direction ; and when the boxes are moved to the other extremity, then the first pinion will be disengaged, and the second be locked to the axle, and cause it to turn round in a direction the reverse of that in which it moved before. There is a lever on another axle, whose office is to move the before- mentioned boxes backwards and forwards; an arm projects from the axis, which moves between two pieces, proceeding from the frame connected with the boxes; the lever rises up- wards, and has a weight at its top, by which it presses strongly in either direction, when it passes the perpendicular position; forming thus the contrivance vulgarly called a tumbling bob, which is used in various engines for a similar purpose. Upon the same axle on which the pinions move is fastened a drum wheel, round which passes the chain or cord to which the buck- ets are attached; another chain or cord is placed below the buckets, from the bottom of one to that of the other, to form an equilibrium between the whole of the appendage of one bucket and that of the other in all positions. A bar is so placed, that, R. E. V. R H I DICTIONARY OF MECHANICAL SCIENCE. 889. on one of the buckets rising to a certain height, it catches the bar, forces it upwards, and thereby throws over the tumbling bob connected with its other extremity : this reverses the move- ment of the buckets; and, on the other bucket rising, it operates in the same way on another lever, which throws the bob to the other side, and causes the first bucket to rise again. - Prony has annexed a contrivance to this engine, by which the horse that puts it in motion is disengaged, when any acci- dent happens which would tend to stop the movement of the wheels: for this purpose, the traces pass under two pulleys in the ends of the yoke ; and their extremities, which have loops wrought in them, are alternately attached to two pins in a "roller, round which a cord is wound two or three turns, and passes from thence through rings in the lever, (which causes the arbor to revolve,) and over a pulley on the arbor to a weight which hangs beside it. When the draught exceeds this weight, it is evident the roller will be drawn round by the traces, and that they will slip off the pins, and be disengaged during the first revolution. The method of reversing motion by causing pinions to be operated upon by the opposite parts of a face-wheel, has been long known and practised by millwrights; and they have various contrivances for performing the alternation, as by levers, screws, tumbling bobs, &c. One of these will be illustrated by a figure, when we come to the article TIDE Mill. As to the second general method, it has, perhaps, an appear- ance of greater simplicity; though, when reduced to practice, it is commonly found more expensive than the former. Suppose, that while the horizontal wheel A, in the annexed figure, con- tinues to 'turn always one way, it is re- quired to have the horizontal wheel B turn, sometimes in one direction, and sometimes in another: by means of an additional wheel C, equal in diameter and number of teeth, (supposing the velocities in both directions to be equal,) this may be accomplished, - - - thus:—Let the two wheels B and C have the lower pivots of their axles resting in boxes or cases that may be moved up and down by means of screws; and, while the wheels A and B are nearly of equal thickness, let the wheel C be somewhat more than double the thickness of either: when the motion of the wheel B is to be in a contrary direction to that of A, let the wheel C be lowered so much that its teeth play neither into those of A nor B, while the teeth of A take into those of B, and drive it round; when. On the contrary, B is to be moved in the same direction as A, let the wheel B be lowered till its teeth do not come into contact with those of A, and let C be raised until the upper parts of its teeth take between those of the wheel A, while the lower parts of the other teeth play into the teeth B ; so shall the rotation of B have the direction required. If the motion of the wheel A were sometimes in one direction, and sometimes in another, the motion of B might, all along, be preserved in one direction, by the occasional application of C as an intermediate wheel. REVIEW, in Chancery, is used for a bill where a cause has been heard, and a decree thereon signed; but some error in law appearing upon the decree, or new matter being discovered after it was made, this bill is given for a fresh examination into the merits of the cause. Review, in War, is the appearance of an army, or part of an army, in order of battle, and their being viewed by the gene- ral, that he may know the condition of the troops. REVIEW, is also the name of one kind of periodical publi- cations, now too much prostituted (under the shelter of anony- mous criticism) to the purposes of the malice of rival authors, and the petty artifice of interested booksellers. REVISE, among Printers, a second or third proof of a sheet to be printed; taken off in order to be compared with the last proof, to see whether all the mistakes marked in it are actually corrected. REVIVOR, BILL of, in Chancery, is a bill for reviving a cause, where either of the parties dies after the bill and answer, and before the cause is heard ; or if heard, before the decree is inrolled ; in which case the bill must be brought, praying that the former proceedings may stand revived, and be put on the samºing as at the time of the abatement. REVOCATION, in Law, signifies the recalling, or anulling and making void, some power, grant, deed, &c. made before. REVOLUTION, the motion of a body or line about a centre which remains fixed. Period of Revolution, in Astronomy, is the time a planet, Comet, &c. employs in passing from any point in its orbit to the same point again. This, with regard to the earth, is what determines the length of the year. See Year. And for the times of revolution of the other planets, see Period and PLANET. REYNEAU, CHARLes RENE, a reputable French mathema- tician, was born in 1650 at Brissac, in Anjou. He taught phi- losophy at Pezenas and Toulon; and in 1683 was appointed to the mathematical professorship at Angers, where he died in 1728, at the age of 78 years. - RHABDOLOGY, a name given by Napier to his method of performing multiplication, division, &c. by means of small bones or rods. See Napier’s Rops. . RHAPSODI, in Antiquity, persons who made a business of singing or reciting pieces of Homer's poems. Cuper says, that the rhapsodi were clothed in red when they sung the Iliad, and in blue when they sung the Odyssey. RHAPSODOMANCY, an ancient kind of divination, per- formed by fixing on a passage of some poet at hazard, and then reckoning on it as a prediction of what should come to pass. RHEA AMERICANA, the American ostrich, in size is very little inferior to the common one; the bill is sloped not unlike that of a goose, being flat at the top and rounded at the end; the eyes are black, and the lids furnished with hairs; the head is rounded, and covered with downy feathers; the neck is two feet eight inches long, and feathered also ; from the tip of one wing to that of the other extended, the length is eight feet; it cannot fly, but it runs very swiftly ; the legs are stout, and bare of feathers above the knees, and furnished with three | toes, all placed forwards, each having a straight and stout claw | as in the cassowary; on the heel is a callous knob serving in the place of a back toe ; the general colour of the plumage is dull gray mixed with white, inclining to the latter on the under parts; the tail is very short, and not conspicuous, being en- tirely covered with long loose and floating feathers, having its origin from the lower part of the back and rump, and entirely covering it; the bill and legs are brown. RHETICUS, GeoRGE JoAcHIM, a distinguished German astronomer, and mathematician, was born at Feldkirk in the Tyrol, in 1514, and for some years assisted the celebrated Copernicus in his astronomical labours. He died in 1576, near 63 years of age. RHETORIC, in the most extensive sense of the word, de- notes the art of composition, or that which enables us to apply language or speech to the best possible advantage. According: to etymology, which often affords the most satisfactory explai nation of words, it signifies the art of pouring forth a stream of sentiment, and communicating with fluency our feeling and thoughts to others. Taken in this point of view, rhetoric will comprehend all polite literature, poetry perhaps excepted, the belles-lettres of the French, the pathetic and pleasant of every kind; compositions whose aim and end is not so much to inform or satisfy the understanding, as to move, incline, and persuade, by addressing the imagination, the affections, and in some mea- sure sensation itself. There cannot be a better rule for com- position, and one more plain and practical, than what is laid down by Cicero : “We are first to consider what is to be said ; secondſy, how ; thirdly, in what words; and lastly, how it is to be ornamented.” See the Editor's Grammar of Rhetoric and Polite Literature, Dr. Hugh Blair’s “Rhetoric,” Dr. Campbell's Philosophy of Rhetoric, &c. RHEUM, RHUBARB, a genus of the monogynia order in the enneandria class of plants, and in the natural method ranking under the 12th order, holoraceae. There is no calyx; the co- rolla is sexfid and persistent; and there is one triquetrous, seed. There are seven species. - RHEUMATISM, a well-known painful distemper, coming, as is supposed, from acrid humours. RHINOCEROS, in Natural History, a genus of mammalia of the order Ferae. Generic character; horn solid, perennial, conical, seated on the nose, but not adhering to the bone. This quadruped is exceeded in size only by the elephant. Its usual 10 HR 890 R I D R H Y ' DICTIONARY OF MECHANICAL SCIENCE length, not including the tail, is twelve feet; and the circum- ference of its body nearly the same. Its nose is armed with a horny substance, projecting, in the full-grown animal, nearly three feet, and is a weapon of defence, which almost secures it from every attack. Even the tiger, with all his ferocity, is but very rarely daring enough to assail the rhinoceros. Its upper lip is of considerable length and pliability, acting like a species of snout, which, grasping the shoots of trees and various substances, conveys them to the mouth, and it is capable of extension and contraction at the animal’s convenience. The skin is, in some parts so thick and hard as scarcely to be penetrable by the sharpest sabre, or even by a musketball. These animals are found in Bengal, Siam, China, and in several countries of Africa, but are far less numerous than the elephant, and of sequestered solitary habits. The female produces only one at a birth; and at the age of two years the horn is only an inch long, and at six only of the length of nine inches. It is generally, however, quiet and inoffensive. Its food consists entirely of vegetables, the tender branches of trees, and succulent herbage, of which it will devour immense quantities. It delights in retired and cool situations, near lakes and streams, and appears to derive one of the highest satisfactions from the practice of rolling and wal- lowing in mud; in this respect bearing a striking resemblance to the hog. This animal was exhibited by Augustus to the Romans, and is supposed to be the unicorn of the scripture, as it possesses the properties ascribed to that animal, of magnitude, strength, and swiftness, in addition to that peculiarity of a single horn, which may be considered as establishing their identity. The two-horned rhinoceros, is similar in size and manners to the former, and is principally distinguished from it by having two horns on its nose; the first being always the largest. RHINOCEROS AVIS, in Ornithology, a name given to a species of Indian raven, the beak of which being remarkably fine, and having a horn-like protuberance on its upper part, is frequently brought to Europe. It is an ugly bird, has a very rank smell, is larger than the English raven, and feeds on carrion. RHINOMACER, a genus of insects, of the order coleoptera. RHODIUM, a new metal discovered among the grains of crude platina by Dr. Wollaston. RHODORA, (Canadian Rose-blossom,) a genus of the decan- dria monogynia class and order. RHOMBOIDES, in Geometry, a quadrilateral figure, whose opposite sides and angles are equal, but which is neither equi- lateral nor equiangular; or it is an oblique angled parallelogram. RHOMBOIDIA, the name of a genus of spars, given them from their being of a rhomboidal form. They derive this figure from an admixture of particles of iron, and consist of six planes. THOMBUS, in Geometry, an equilateral rhomboid, or a quadrilateral figure, whose sides are equal and parallel, but the angles unequal ; the two opposite ones being obtuse, and the other two acute. RHUBARB. See RH EUM. RHUMB, in Navigation, a vertical circle of any given place, or the intersection of such a circle with the horizon, in which last sense the rhumb is the same with the point of the compass. RHUMB LINE, or Loacodromia, in Navigation, is a line pro- longed from any point in a sea chart, except in the direction of any of the four cardinal points; or it is the line described by a ship while her course is constantly directed towards one and the same point of the compass, except the four above men- tioned, that is, while she crosses all the meridians at the same angle, providing this is not a right one, and this angle is called the angle of the rhumb ; and that which it makes with the equator, or a parallel to the equator, is called the complement of the rhumb. If a vessel sail either north or south, it evidently describes a great circle of the sphere, or part of such a circle; and if her course is either due east or due west, she cuts all the meridians at right angles. But if her course is oblique to these principal points, then she no longer describes a circle, but a sort of spiral, the characteristic property of which is, that it cuts all the meridians at the same angle, and is thence deno- minated the loxodromia, or loxodromic curve, or rhumb line, which, though it continually approaches towards the pole, can never arrive at it, except after an infinite number of revolutions. RHYME, See PoETRY. RHYTHMICAL, in Music, an epithet applied to the pro- perty, or quality, in the ancient melopoeia, and modern melody, by which the cadences, accents, and quantities, are regulated and determined. RIBAND, or RIBBon, a narrow sort of silk, chiefly used for head ornaments, badges of chivalry, &c. RIBANDS, in Naval Architecture, long, narrow, flexible pieces of timber, nailed upon the outside of the ribs from the stem to the sterm-post, so as to encompass the ship lengthways; of these the principal are the, Floor RIBAND, which terminates at the height of the rising line of the floor; and the Breadth RIBAND, which coincides with the wing transom, at the height of the lower-deck : all the rest are termed interme- diate ribands. The ribbands being judiciously arranged with regard to their height and distance from each other, and forming regular sweeps round the ship's body, will compose a kind of frame, whose inte- rior surface will determine the curve of all the intermediate or filling timbers, which are stationed between the principal ones. As the figure of a ship's body approaches to that of a conoid, and the ribands having a limited breadth, it is apparent that they cannot be applied to this convex surface without forming a double curve, which will be partly vertical and partly horizon- tal, so that the vertical curve will increase by approaching the stem, and still more by drawing near the stern post. It is also evident, that by deviating from the middle line of the ship’s length, as they approach the extreme breadth at the midship frame, the ribands will also form a horizontal curve. From this double curve it results that the ribands will appear in dif- ferent points of view when delineated on different planes of the same ship. RIBES, the currant and gooseberry bush, a genus of the monogynia order in the pentandria class of plants, and in the natural method ranking under the 36th order, pomaceae. RIBS of a Parrel, are short pieces of plank, each having two holes in it, through which the two parts of the parrel-rope are received, the inner smooth edge of the rib resting against and sliding readily up and down the mast. RICCIOLI, JoANNES BAPTISTA, a learned Italian astrono- mer and mathematician, was born at Ferrara, a city in the papal dominions, in 1598, and died in 1671, in the 73d year of his age. RICHERIA, a genus of the class and order dioecia pentan- dria; a tree of great size. RICINUS, or PALMA Christi, a genus of the monadelphia order, in the monoecia class of plants, and in the natural me- thod ranking under the 38th order, tricoccac. RICKETS, a disease affecting children, and principally characterized by enlargement and inflexure, or distortion of the bones. RICOCHET FIRING, in the Military art, is a method of firing with pieces elevated from three to six degrees, and loaded with a small charge, so that the ball may bound and roll along inside the parapet. The ball or shot thus discharged, goes bounding or rolling, killing or maiming all it meets with in its course, and creates much greater disorder, by thus moving slowly, than if thrown from the piece whose elevation is greater, with much greater violence. - RIDDLE, in rural economy, a sort of sieve, used to separate the grain from dust, and the seeds of weeds. In Mineralogy, the riddle is used to separate the ore from surrounding rubbish. RIDE (To) Head to Wind, is when the wind is so much more powerful than the tide, as to cause the ship to swing till her head is in the direction of the former. To Ride Athwart, or between Wind and Tide, is when the wind and tide are in opposition, but so nearly equal in their force. that the ship rides with the tide running against one side, and the wind blowing upon the other. To Ride out a Gale, signifies that the ship does not drive during the storm. To RIDE Easy, is said of a ship when she does not labour or feel a great strain upon her cables. To Rupe Hard, is, on the contrary, to pitch violently in the sea, so as to strain her cables, masts, or hull. To Ride a Head-rope of a Sail, &c. is to shake and stretch it by treading upon it while a purchase is employed at the end R. I Gº R. I. N. DICTIONARY OF MECHANICAL SCIENCE. 891. to extend it. A rope is said to ride when one of the turns by which it is wound round lies over another, so as to interrupt the operation, or prevent its rendering. RIDERS, a sort of interior ribs, fixed occasionally in a ship’s hold, opposite to some of the principal timbers to which they are bolted, and reaching from the keelson to the beams of the lewer-deck, and sometimes higher, in order to strengthen her frame. They are bolted to the other timbers to support them when it is apprehended the ship is not sufficiently strong in the part where they are fixed, which is generally a-midships. They have also their floor pieces and futtocks, and sometimes their top pieces, and being scarfed to each other in the same manner as the timbers, they have similar distinctive appellations, es the RIDER Futtocks; Lower Futtock RIDERs ; Middle Futtock RIDERs; Upper Futtock RIDERs; Floor RIDERs. See the arti- cle Floor. The riders ought to be stationed so as to lie between two ports of the lower deck, and to correspond with the timbers to which they are attached, in such manner as that the scarfs of the riders may be clear of the timbers. They are scored upon the keelson, clamps, and thick stuff of the bottom. They are secured by bolts, which are 'driven from without, so as to penetrate the outside planks, the timbers, the clamps, and the riders, on the inside of which last they are fore-locked. These pieces are rarely used in merchant-ships, on account of the space they occupy in the hold; neither are they generally used in vessels of war, at least, till the ship is enfeebled by service. RIT) GE, a long narrow assemblage of rocks, lying near the surface of the sea. RIDGES, in Agriculture, are pieces of ground laid up be- tween two furrows, having always considerable length, but of small breadths. RIDING, a corruption of Trithing, now chiefly used as divi- sions of Yorkshire, of which there are three. RIDING Clerk, one of the six clerks in chancery, who, in his turn annually keeps the controlment books of all grants that pass the great seal that year. RIFLE, a firm-arm which has the inside of its barrel cut with from three to nine or ten spiral grooves, so as to make it resem- ble a female screw, varying from a common screw only in this, that its grooves or rifles are less deflected and approach more to a right line; it being now usual for the grooves with which the best rifled barrels are cut, to take about one whole turn in a length of thirty inches. The number of these grooves differ according to the size of the barrel and the fancy of the work- man; and their depth and width are not regulated by any invariable rule. RIG, To, is to fit the shrouds, stays, braces, &c. to their re- spective masts and yards. To RIG wr a Boom, is to draw it in from a situation upon the º of i yard, bowsprit, or another boom, &c. to extend the foot Of a Sali. RIGGERS, men who make a livelihood by going on board ships to fit the standing and running rigging. It is also a name given in the navy to any party of men sent to the rigging loft or hulk, to prepare the standing rigging for putting over the mast-heads. RIGGING, a general name given to all the ropes employed to support the masts, and to extend or reduce the sails, or arrange them to the disposition of the wind. Standing RIGGING, is that which is used to sustain the masts, and remains in a fixed position; as the shrouds, stays, and back-stays. Running RIGGING, is that which is fitted to arrange the Sails, by passing through various blocks in different places about the masts, yards, shrouds, &c, as the braces, sheets, halliards, clew-lines, &c. &c. - Lower RiGGING, is that which attaches to the lower masts. Top-Mast RIGGING, consists of the top-mast shrouds, stays, and back-stays. RiGGING-Loft, a kind of long room or gallery in a dockyard, where the standing riging is fitted by stretching, serving, spli- cing, seizing, &c. to be in readiness for the ship. RIGHT, in Geometry, signifies the same with straight; thus a straight line is called a right one. RIGHT, in Law, not only denotes property, for which a writ of right lies, but also any title or claim, either by virtue of a condition, mortgage, &c. for which no action is given by law; but an entry only. ,' . RIGHT ANGLE, Cone, Cylinder, Sphere, &c. See their respec- tive substantives. RIGHTING, the act of restoring a ship to her upright posi- tion after she has been laid upon a careen, which is effected by casting loose the careening tackles, and, if necessary, heaving upon the relieving-tackles. A ship is also said to right at sea, when she rises with her masts erect, after having been pressed down on one side by the effort of the wind upon her sails. To RIGHT the Helm, implies to replace it in the middle of the ship, after having put it out of that position. RIGHTS, BILL of, a declaration delivered by the lords and commons to the Prince and Princess of Orange, Feb. 13, 1688, and afterwards enacted in parliament, when they came to the throne. This may be considered as one grand foundation of English liberty. RIGIDITY, a brittle hardness; or that kind of hardness which is supposed to arise from the mutual indentation of the component particles of a body. RILL, in Agriculture, a small runlet of water, mostly rising on the sides of gentle declivities; they are sometimes matural, and sometimes artificial. - - RIM, or BRIM, a name given to the circular edge of a top. Tbe circumference or circular part of a wheel. RIND, a skin of any fruit that may be cut off. The outer coat of the chesnut set with prickles, particularly has this name. RING, for the finger, an ornament of great antiquity and general use, frequently used as badges of office, and denoting the quality of the wearer. RING, in Navigation and Astronomy, a brass instrument made in the form of a ring, and serving to take the altitude of the sun. | RING Bolt, an iron bolt with an eye at one end, wherein is fitted a circular ring. They are used for various purposes, but more particularly for managing and securing the cannon; and are, for this purpose, fixed in the edges of the gun-ports. They are driven through the plank and the corresponding beam or timber, and retained in this position by a small pin thrust through a hole in the small end. RING Ropes, short pieces of rope, tied occasionally to the ring- bolts of the deck, to stopper or fasten the cable more securely when the ship rides with a heavy strain, - RING Tail, a quadrilateral sail extending on a small mast, which is occasionally erected for that purpose on a ship’s taffa- rel, the lower part being stretched out by a boom, which pro- jects over the stern horizontally. RING Tail, is also the name of a kind of studding sail hoisted beyond the afteredge of those sails which are extended by a gaff and a boom over the stern. The two lower corners of this sail are stretched out to a boom called a RING Tail Boom, which rigs in and out upon the main or driver boom, in the same manner that a studding sail boom does on the top-sail yards. RiNG Worm, in Medicine, a popular appellation given to various superficial affections of the skin, which assume some- what of a circular form. The kinds are very diſſerent, and require very different treatment. RING of SATURN, in Astronomy, is a broad, opaque, circular body, encompassing the equatorial regions of that planet, at a considerable distance from him ; which presents, under favour- able circumstances, one of the finest telescopic objects in the heavens. An apparent irregularity was first observed in the form of Saturn by Galileo, but his telescope was not sufficiently powerful for him to discover the cause of it; this, however, | was soon after effected by Huygens, who, in consequence, pub- | lished his “ New Theory of Saturn,” in 1659. This ring, which is very thin, not exceeding 4500 miles, is inclined to the plane of the ecliptic in an angle of 31°19' 12"; and revolves from west to east in 10h 29m 16"-8, being nearly the time of the diurnal revolution of Saturn, and which is also found, from the laws of Kepler, to be the time in which a satellite would revolve about that planet at the mean distance of the ring; a very remarkable confirmation of the universality of the laws of the planetary motions. This rotation is performed about an axis perpendicu- 892 R. I. V. R. I. O’ DICTIONARY OF MECHANICAL SCIENCE. lar to the plane of the ring, and passing through the centre of the planet. The ring being, as we observed above, very thin, it sometimes nearly disappears, that is, when its plane coin- cides with or passes through the centre of the earth or sun, at which time it subtends an angle of not more than half a second, and can therefore only be discovered by the most powerful telescopes, through which it has then the appearance of a luminous line beyond the body of the planet. And as this plane is presented to the sun twice during each sidereal revolution of the planet, the disappearance of the ring will happen about every 15 years, and at nearly the same intervals it will appear to the greatest advantage. When viewed in the most favour- able position, with a magnifying power of 700, the ring is observed to be divided into two unequal portions by a black concentric line, which is now ascertained to be a real separation, and that what we call the ring of Saturn consists at least of two rings; and some astronomers have even supposed it to be still farther subdivided, and to consist of several circular parts, but this at present is little more than conjecture. The dimen- sions of this double ring, as given by Dr. Herschel, are as follow :— Eng. Miles. Diameter of the planet, ... ... . . . . . . . . . . . . . . . 76068 Inside diameter, smaller ring, . . . . . . . . . . . . . ... 146345 Outside, . . . . . . ... • - - - - - tº e o 'º e º & e º e º º e me ... . . . . 184393 Inside diameter, larger ring, . . . . . . . . . . . . . . . . 190248 Outside, . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204883 Breadth of the inner ring, . . . . . . . . . . . . . . . . . . 20000 - —— of the outer ring,... . . . . . . . . . . . . . . . . 7200 Space between the rings, . . . . . . . . . . . ....... . 2839 —— between the planet and ring, .......... 70277 Mean thickness of ring, . . . . . . . . . . . . . . . . . . . . 4500 The intersection of the plane of the ring with the ecliptic is in 5s 20°, and 118 20°, in which points therefore it disappears, and between these, viz. at 2s 20°, and 8s 20°, it appears most brilliant. As the plane of the ring coincides, or nearly coincides, with the equator of the planet, it is obvious that the ring never becomes visible in his polar regions, and even in those parts nearer the equator it must be very frequently eclipsed by the planet, which last, on the contrary, is as frequently eclipsed by the ring ; whence it does not seem that it can be designed to supply these remote regions with light, as some have supposed, as it rather serves to render them more dreary and comfortless; well might the poet say, “One moment's cold like theirs would pierce our bone, Freeze our heart's blood, and turn us all to stone.” RIOT, rout, and unlawful assembly. When three persons, or more, assemble themselves together, with an intent mutually to assist each other against any who shall oppose them in the exe- cution of some enterprise of a private nature, with force or violence, against the peace, or to the manifest terror of the people, whether the act intended were of itself lawful or unlaw- ful ; if they only meet with such purpose or intent, though they shall after depart of their own accord without doing any thing, this is an unlawful assembly. By 34 Edward III. c. 1, it is enacted that if a justice find persons riotously assembled, he alone has not only power to arrest the offenders, and bind them to their good behaviour, or imprison them if they do not offer good bail; but he may also authorize others to arrest them by a bare verbal command, without other warrant: and by force thereof, the person so commanded may pursue and arrest the offender in his absence, as well as presence. It is also said, that after any riot is over, any one justice may send his war- rant to arrest any person who was concerned in it, and that he may send him to gaol till he shall find sureties for his good be- haviour. The punishment of unlawful assemblies, if to the number of twelve, may be capital, according to the circum- stances which attend them ; but from the number of three to eleven, it is by fine and imprisonment only. The same is the case in riots and routs by the common law, to which the pillory, in very enormous cases, has been sometimes superadded. By the act 1 George II. cap. 5, sect. 2, every justice, sheriff, mayor, &c. Shall, upon notice of a riot, or unlawful tumultuous assembly of twelve persons, proceed to the place, and make proclamation for them to depart, upon pains of that act com- monly called the riot act. If any person shall wilfully oppose or hurt any person going to make proclamation, and prevent the same, he shall be guilty of felony without benefit of clergy. If twelve continue together after proclamation for one hour, it is felony in like manner. And every justice, &c. shall apprehend persons; and if the rioters are killed, the justice, &c. shall not answer for it. A riot, though of fewer persons than twelve, to destroy any church, chapel, meeting, or dwelling- house, out-house, &c. is a capital felony; and the hundred shall answer the damages as in case of robbery. If two justices go out to quell a riot, they may assemble the posse comitatus, and every person capable of travelling is, upon being warned, to join them on pain of imprisonment. 13 Henry IV. c. 7, s. 1, 2, 11, 5, c. 8, s. 2. It is no uncommon thing to hear, when accidents have occur- red at riots, that though the riot act has been read by a magis- trate, the people who suffer, or those who make their appear- ance before a coroner’s jury, for the most part swear they never heard one syllable of the act read. In order to announce that the riot act has really been read, the editor once proposed to Viscount Lord Sidmouth, that a flag should be unfurled by the magistrate, or his officer, when the riot act had been read to a seditious or ill-disposed mob. They could all see the flag, who were not blind, though they might not all hear the magistrate's voice, and would be left without excuse, if they did not disperse when the symbol of good order was unfurled in their sight. RIPPLING, a broken and interrupted noise, produced by a current on or near the sea-coast : the effect of which is also apparent to the eye, by occasioning an ebullition or bubbling up of the water. RISING, in Astronomy, the first appearance of the sun, moon, or other celestial body, above the horizon. RISING Line, a name given by shipwrights to an incurvated line drawn on the plane of elevation, to determine the height of the ends of all the floor timbers throughout the ship's length and which accordingly ascertains the figure of the bottom with regard to sharpness or flatness. RISK, the hazard or chance of loss, damage, &c. against which insurances are generally effected; such as against fire, Seas, tempest, enemies, &c. RITUAL, a book directing the order and manner to be ob- served in celebrating religious ceremonies and performing divine service, in a particular church, diocese, order, or the like. RIVER, in Geography, a stream or current of fresh water, flowing in a bed or channel from its source or spring into the sea. In Commerce and Political Economy, we may define a river to be a moving road, and the nurse of canals or inland naviga- tion. The doctrine which relates to the flux, reflux, motion, and discharge of rivers, is a branch of hydraulics, and as such forms a part of the present work, though our limits will only admit of a slight sketch of the theory. Water running in open canals or rivers, is accelerated in consequence of its depth, and of the declivity on which it runs, till the resistance increasing with the velocity, becomes equal to the acceleration, when the motion of the stream becomes uniform. But this resistance, it is obvious, can only be determined by experiment; and hence several philosophers have undertaken different courses of expe- riments for this purpose, amongst whom Buat and Leslie seem to have met with the most complete success. The same principles which regulate the motion of water in pipes and along canals, extend likewise to the flow of rivers in their beds. Since the propelling power is proportional to the elevation of the main source, the celerity acquired by those descending streams would become enormous, if the force were not gradually absorbed by the operation of some constant impediments. Suppose, such a river as the Rhone to receive its principal waters at the altitude of 900 feet above the level of the sea, and that no system of obstruction had intervened in its course, it would have shot into the Bay of Marseilles with the tremendous velocity of 240 feet in a second, or at the rate of 164 miles every hour. Even an inferior stream, like the Thames, fed at the height of only a hundred feet, would still, if not retarded by the attrition of its bottom and sides, have rushed into the sea with a velocity of 54% miles in an hour. The resistance of fluids, like the friction of solids, thus enters largely into the economy of nature. As the latter is the great principle of stability and consolidation, so the former serves most essen- tially to restrain the accumulation of celerity, and to moderate, R. I. V R. I. V. 893 DICTION ARY OF MECHANICAL SCIENCE. all violent motions. A current presses forwards with increasing rapidity, till the obstruction which it encounters becomes at last equal to the inciting force ; and having attained this limit, the water then continues to flow in a uniform stream. The main- taining power is proportional to the quantity of descent in a given space; but the impeding influence depends on the surface of the bed of the river compared with its volume. This obstruc- tion must augment very fast, being as the square of the celerity. If a river should wind considerably, the multiplied deflexions which it suffers, must still farther impede its motion. In every bend which it makes, part of its impulse will be spent against the concave side of the channel ; the centrifugal cffort will like- wise raise the surface of the water in those sinuosities, and therefore augment the abrasion of the banks. Hence, no stream can be long confined to a rectilineal channel. If an accidental swell should once effect a breach, the sweep of the current must necessarily tend to enlarge the concavity by an accelerat- ing progression; the opposite shore, from the accumulation of gravel and other deposits, gradually advancing into the chan- nel. Rivers thus naturally form sinuosities; they seek to meander over the plains; and they would incessantly change their beds, if not restrained by sedulous attention and skilful hydraulic operations. In such a country as Italy, the superin- tendence of water-courses constitutes an important department of government. If a flat surface be directly opposed to the action of a stream as it shoots from the side of a vessel, it must evidently sustain a pressure just equal to that which actually projected the fluid, or the load of the incumbent column. In every case, therefore, the impulsion of any current against a perpendicular plane, may be estimated by the weight of a body of the fluid standing upon that surface, and having the altitude due to the velocity. The pressure of a river against the piers of a bridge, may be hence computed. The shock becomes augmented in a high ratio during floods; for not only is a greater extent of surface then opposed to the current, but the effort on every given space follows also the square of the increased velocity. The mighty rush of a torrent, carrying along with it fragments of rock, stones, or gravel, depends on the same principle. A torrent, with the celerity of eight miles an hour, would therefore be capable of rolling a stone of four foot in diameter. But a stream gliding at the rate of two miles an hour, would only be sufficient to carry along with it a pebble of three inches in diameter. With lower velocities, the current will scarcely move gravel. If the particles of sand were supposed to have a diameter equal to the twenty-fourth part of an inch, it would require a flow of a quarter of a mile in an hour to bear them along. A velocity of the tenth part of a mile in an hour, would only be sufficient to carry sandy particles of the hundred and twenty-third part of an inch in diameter. Hence the theory of the washing of metallic ores, and the deposition of gold dust in the beds of rivers. The ores being broken into very small fragments by means of a stamper, these are laid upon an inclined plane, and exposed to the action of a descending stream of water, which sweeps away all the lighter earthy par- ticles. In like manner the pellicles of gold, adhering com- monly to minute portions of quartz, being at length detached by incessant rolling, are left in the little pools, while the sandy particles are still carried farther. Hence also the reason why the bottoms of rapid rivers are covered with large round stones, or at least with rolled pebbles. Where the celerity of the cur- rent becomes moderated, gravel and coarse sand begin to appear. But when the flow is sluggish, the bed of the river is always covered with fine sand or mud. Such deposits occur chiefly in the pools, and near the influx into the sea. Hence likewise the gradual formation of banks, a process which is constantly going on over all the stagnant parts of water, and along the limits of opposite currents. - The float-board of a river mill is impelled, not by the whole velocity of the stream, but only by the excess of this above the velocity of the board itself. Hence it would be more advan- tageous to make the float-boards turn slower, and to multiply their velocity afterwards by means of a train of internal ma- chinery. The current might then strike with nearly its full celerity. In the case of undershot wheels, a grate loss of power is occasioned by the accumulation of the dead water, or 91-2, of the water which, having impinged against a float-board, remains nearly stagnant, and therefore impedes the advance of the next float-board. The shock will evidently be the same, whe- ther a current strikes against a fixed plane, or the plane itself moves with an equal and opposite velocity through a fluid at rest. The formula of impulsion already given, must hence include likewise the case of resistance, which is therefore pro- portional to the square of the celerity. But this conclusion might be derived from direct considerations. As the plane advances, it receives the stroke of all the particles in 1ts pro- gress. The quantity of momentum thus consumed, is evidently compounded of the number of particles encountered, and the impetus of each; but the number and individual force of those particles being as the velocity, the combined effect must be proportional to the square of the velocity. - On Dredging Machines, with a description of one at present employed to deepen the river Clyde.—Dredging was first em. ployed by the Dutch to clean the bars or entrances of their harbours and navigable canals. The first machines were not contrived for lifting mud, gravel, &c. but only for loosening it, so that the sluices constructed for the purpose of cleaning, or scouring, might have more effect. They consisted of large bars, or prongs, placed vertically in a wooden frame, which being fastened to a vessel in the line of the sluices, the whole was impelled forward by the current, and produced a most effectual Scour. The first kind of dredging machines used to any extent in this country, consisted of a large plate of iron, about four feet long, and eighteen inches deep, sharpened on To each end of it a plank of hard wood was fixed to tenons cut in the iron, whose sharpened edge projected about four inches below the wooden sides, which should be about five long, tapering to ten inches deep at the point, where a bar of iron is fixed to keep the two ends asunder. The whole is formed somewhat like a box, without top or bottom, eighteen inches at one end, and ten inches at the other. To the two ends of the wood a chain is fixed for attaching the principal working rope, or chain. To put the machine in motion, a punt was moored on each bank of the river, directly opposite, and a capstan, or windlass, on each, the one for drawing across the empty dredge, and the other for bringing it back. In the course of its passage, the dredge was commonly filled, and by means of the capstan raised so high, that at low water the stuff could be removed with shovels. Where the shiftings are not frequent, a capstan may be placed on the bank of the river, and the opera- tion carried on as described. Machines on this principle were employed for many years in deepening the Clyde between Glasgow and Dumbarton. Improved dredging machines, on the principle of an endless chain, were next employed on a large scale, but they have undergone various improvements pointed out by experience. When these machines were first constructed horses were em- ployed as the moving power, which had a circle appropriated to them on board of the vessel that carried the machinery, and were taught to stop by the ringing of a bell. Such machines were long in use in the Humber, at Hull, and in the Clyde at Port-Glasgow and Greenock; those employed at the latter place, had the moving power communicated by men and crane- work. The vessels built for them were very flat, and square at both ends, having an aperture up the middle, through which the bucket-frame works, and the stuff was discharged over the end. The application of the steam-engine, however, as a moving power, soon superseded all other modes of performing the operation. Dredging machines, wrought by steam, have been in use on the Thames, at Hull, Bristol, Sunderland, and Aber- deen, and also on that great national undertaking the Caledo- nian canal. The one which has been lately constructed by Messrs. Girdwood and Co. in Glasgow, and which is at present employed in deepening the river Clyde, so as to admit of large vessels being brought up, does not differ much in its construc- tion from those employed in the Thames and Caledonian canai. The figure exhibits an elevation of this machine, with the vessel which contains it. The dredge is situated, in this ma- chine, in the centre of the vessel, which has an opening of about two-thirds of its length from the stern, to allow the machine room to touch the bottom to be deepened. The space on each | Side of this opening in the vessel is fitted up with hammocks, the under edge. 10 S 894 R O A. R. I X DICTIONARY OF MECHANICAL SCIENCE. &c. for the accommodation of the workmen. The remaining part of the vessel towards the head or bow, is occupied by the steam-engine, boiler, stalk, &c. and the dredge discharges the mud and gravel at the stern. When the engine is set on, the motion is communicated to a wheel fixed on the near end of a horizontal shaft, which conveys the motion to another wheel at the farther end, working into a bevelled wheel on the square barrel or axis on which the buckets revolve. The buckets, twenty-two in number, are placed on the links of two endless chains, connected together by the fastenings of the buckets, and revolving round the bucket frame; the length of each link is made to correspond to the side of the square barrel or axis, revolving in the upper end of the bucket-frame, which is sup- ported on the deck of the stern. A similar square barrel or axis, is placed at the lower end of the bucket frame which is immersed in the water, and is elevated or depressed, according to the depth of the bottom, by a chain and pulleys, the end of which terminates in a barrel turned by the engine, when required. When the process of deepening commences, the lower end of the bucket-frame is allowed to descend till it touches the bottom, so that when each bucket arrives at this end of the frame, it scoops out and takes up a load of mud or gravel, and is carried round by the revolving of the chain. This chain, when loaded with the buckets, is supported on the upper side of the bucket frame, by means of a series of rollers, which prevent the great friction which would otherwise be occasioned by the dragging of the heavy buckets on the frame. As each bucket passes over the upper end of the frame, it discharges its contents into punts brought a stern of the vessel. While this process is going on, the vessel is made to move forward by means of a capstan slowly wrought by four men. This capstan winds in a chain made fast to an anchor consi- derably ahead of the vessel. The punts are first loaded on the one side, and, are then turned round to receive a load on the other; when full, they are floated away to the edge of the river, whence the stufi taken out of the bottom is laid alongside of its, banks. The quantity brought up at any time must vary considerably, from the nature and depth of the bottom ; we have heard it stated, that 30 tons have been raised in seven minutes, in favourable circumstances. *- º Š--ºft, • - --- <-- .--- - - - --- “…cº- - ---- - - a, is the cngine-house; b, a covered wheel, communicating motion from the engine to the shaft c, on the other end of which is the shaft-wheel d'; e, is the square barrel or axis, on which the buckets o, o, o, revolve; m, is the bucket-frame; m, the double endless chain; i, i, the friction rollers; ºr, r, the regula- ting chains and pulleys; l, the levers for communicating mo- tion to the barrel which moves the chain and pulleys; p, the situation of the punts when receiving the mud or graveſ raised from the bottom. In the dredging machines used in the Thames, there are two dredges, or endless chains with buckets, one on each side of the vessel, working on the outside, which prevents the necessity of an opening in the centre as above. RIXDOLLAR, a silver coin in different countries on the continent, and of different values, viz.:-Rixdollar of Basil, 3s. 64d. ; Denmark, 4s. 63d. ; Hamburgh, 4s. 63d, ; Holland, 4s. 6; d. ; Lubeck, 3s. 8%d.; Poland, 4s. 0#d.; Prussia, 3s. 0d. ; Sweden, 4S. 7}d. ; Germany, 4s. 8d. standard of 1566; ditto, 4s. 2d. standard of 1753. ROACHING of ALUM, one of the last processes used in the making of alum, and rendering it marketable, ROAD, an open way or passage, forming a commodious communication between one place and another. The ancient Romans were much fained for their attention to roads. Many monuments of their skill and industry still exist, after a laps. of sixteen hundred years. - Common Road.-The exertions made to obtain a smooth surface, is at present one of the most conspicuous features in our system of road-making. This has been effected in a wonderful degree, by a greater attention to the general fabric of the road, and by reducing the metal or stones to smaller dimensions. It must, however, be observed by every one, that our best-formed roads very quickly get out of repair, and that the situation of the traveller is rather tantalizing : for no sooner does he feel the comforts of a smooth path, than an irksome tedium ensues, while he passes along newly laid pieces—the road being almost constantly under repair. Where there is much traffic, it abso- lutely requires a continued operation, and an unwearied atten- tion, to keep these fine-spun roads in order. This, indeed, is rendered obvious, even from the quantity of clayey stuff that is raked together in heaps after rains, or is blown about in the state of dust in dry weather. The original cost of a stratum of properly broken road metal, measuring eight inches in depth, in such a situation as Edinburgh, where good rock is to be had in abundance, may be stated to be at the rate of about £2, 10s. per rood of 36 square yards. This course of metal laid upon the several approaches to this city requires to be renewed, or would be wholly worn out, in about three years. In the public streets the waste would be proportionally more rapid ; and this seems to render the use of small metal unsuitable for a much frequented thoroughfare. Where it has been tried in some instances in England and South Wales, the inhabitants complain “of having all the dust of summer and all the dirt of winter.” Causeways.-Were it not for the great expense of causeway, its roughness, and the jarring noise which attends it, this would, no doubt, be generally resorted to both for roads and streets, as is the case in France. The causeway is of two kinds ; one termed ruble, the other aisler. In the former, the stones are irregular both in their figure and dimensions, and they receive hardly any chipping or dressing from the quarrier or paviour. The aisler causeway, on the contrary, consists of stones well assembled, carefully hammer-dressed, and laid in the regular courses across the street, upon a bed of sand. This mode was long considered the perfection of road-making. But the stones being formed with the lower end, or that which is set upon the ground, somewhat smaller than the upper surface, they conse- quently touch only at or near the top. When, therefore, a pres– sure comes upon one end of a stone so formed, and set in lodse sand, it is easily depressed ; when the causeway becomes dis- located, and gets into numerous hollows. The dislocation of the ruble causeway is still more rapid, as the stories rest upon a smaller surface than either the aisler causeway or even the rounded stones in general use in the streets of country towns. These last form a very rough and unpleasant road ; but in con- nexion with the stone-tracks now recommended, they would form most durable and excellent streets. In the neighbourhood of Edinburgh, the expense of aisler causeway is about eight guineas per rood, while ruble work may be estimated at about one half of that sum. Perhaps the finest specimens of British paving are those of the Commacroial Road of London, Great Sackville-street in Dublin, and Lcith-walk of |Bóinburgh. This last forms almost the only thoroughfare to the Port; it is nearly two miles in length, and its breadth between the curb-stones, which line off a spacious footpath on each side, may be taken at an average of 58 feet. It is now fourteen or fifteen years since it was converted from a very bad common road into this spacious causeway. Although the surface of this street now exhibits many inequalities, yet with a very little re- pair it has continued a good road during that comparatively long period, and may continue still as long in the saine state. R. O. A. R () A DICTIONARY OF MECHANICAL SCIENCE. 895 Now, if we gºńpare this with the continual repairs which com- mon roads with a similar traffic demand, we presume that a small metal road would have required to have been renewed every third year, or at least five times, since Leith-walk was paved with aisler causeway. Hence it follows, that in the course of fifteen years, this, which cost eight guineas, must, upon a mo- derate calculation, have cost about fifteen guineas per rood, in- cluding the expenses of raking mud and other contingencies, to which the causeway is but little incident. We here also lay out of view the inconveniency of repairs almost constantly going on, besides the much greater quantity of dust inseparable from the common road. The causeway is, therefore, upon the whole more economical than the smail metal road ; but this last is more pleasant for the traveller. Wheel Tracks of Stone.—If any one can suggest a system of road-making which shall lessen the ultimate expense, and avoid the inconveniency attending the frequent repair of small metal roads, and at the same time secure all the advantages of a smooth and uniform railway, with the duration of the aisler causeway, we doubt not that its importance will at once be admitted: and if its practicability be also evinced, we trust that it will soon be brought to the fair test of experiment, the result of which may lead to its general adoption. Mr. Stevenson, who is known to our readers as the constructor of the Bell Rock Light House, has proposed improvements in most common roads, by laying stone tracks of a simple construction, upon a firm foun- dation, if not throughout the whole extent of our principal roads at least upon all their acclivities which exceed a greater rise than at the rate of 1 perpendicular to 26 horizontal feet. (An undulating line of road, which obliges the carrier, in most in- stances, to modify his load to one-half of what his horse can take along the more level parts.) It is likewise proposed, that the leading streets of all towns and villages situate upon the principal highways, should be laid with these stone-tracks. The traveller would then glide smoothly along, instead of being accompanied with a thundering noise and jolting motion, most unpleasant to himself, and the inhabitants of the respective places through which he passes. Perhaps the advantages of this system cannot be better ex- emplified than by noticing an experiment made in presence of some of the directors of the Forth and Clyde Canal Company, upon a sct of cast-iron tracks, laid upon an acclivity rising at the rate of about 1 in 15 to Port-Dundas near Glasgow. IIere one horse actually drow up a load of three tons on a cart weighing 9 cwt.* In this case the horse proceeded up hill with- out much apparent diſficulty till he reached the top, and was about to enter on the common causeway, when he could proceed no farther although the road had now become level. The cart- ers frequenting this road agree, that their horses had formerly greater difficulty in taking up 24 cwt. on the causeway, than was now experienced , with three tons. How great, therefore, must be the beneficial eſſects of such an immense acquisition of power as even the partial introduction of wheel-tracks is calculated to afford to the traffic of the country. It is to be regretted that cast-iron, which would be so much more durable than Stone, is so expensive. It may also be noticed as a drawback to the use of that material for the thoroughfare of a street, that its property of hardness and of getting smooth, cven to a state of polish, becomes proportionally disadvantageous. The stone- tracks, on the contrary, preserve a certain degree of roughness, and the numerous joinings suggested by this plan are also favourable to the safety of the horse. The individual component stones of the wheel-tracks hitherto * We trust we shall here be excused for attempting to point out to our readers the benefit of light single-horse carts. blem of wealth, but it is really impossible to make even two horses work equally. Much as we admire that noble animal, the dray horse of London, , we cannot approve of the policy of yoking them in teams. Our feelings have, indeed, been often agitated by seeing the whole load of several tons thrown upon the shaft horse at almost every turn from one street to another. We are, however, far from disapproving of four wheels: and with pleasure we notice an improvement lately made in single-horse waggons with four wheels applied to ordinary purposes. These waggons are 10 cwt., on which a horse weigh- ing about 11 cwt., takes a load of 30 cwt. between Edinburgh and Closeburn, a distance of 66 miles. If wheel-tracks were laid upon the principal accli- vities of ordinary roads, horses could work with a load of about two tous, and jolting motion of the causeway. The team is indeed an em- . very partially in use, extend from three to four feet in length, are about ten or twelve inches in breadth, and eight or ten inches in depth. In the neighbourhood of Aberdeen there is a granite railway of this description, which runs several miles along, or in conjunction with the common road. The stones of the tracks should be of a cubical form, measuring only from six to eight inches in the lengthway of the track, and twelve to fourteen inches in depth, cighteen inches in breadth at the base, and twelve inches at the top or wheel-track. The stones are therefore proportionate in all their dimensions ; for, unless they contain a mass of matter corresponding to their length, they will be ſound to want strength and stability. It would hardly be possible to keep slender stone-rails in their places, and hence the chief benefit of a connected railway would be lost. On the other hand, very large materials are diſlicult to be got, and are also more expensive in carriage, and in workmanship, than stones of a smaller size. The Italian wheel-tracks are composed of stones two feet in breadth, and of various lengths. To lessen the risk of horses falling, these broad stones are kept in a rough state, by occasionally cutting grooves with a pick- axe upon their upper surface. A mode of paving with large blocks of granite, chequered or cut in this manner, has been tricd in some of the streets of London. In order, however, to give pavement of this kind the necessary stability, the blocks would require to have their dimensions equally large on all sides, the expense of which would be too great. But cubical Stones of the size now recommended may be procured at a moderate price, and throughout a great range of country; while the tracks, if properly laid, will actually be more stable than if blocks of larger dimensions were employed. For we may notice, that a carriage wheel rests or impinges even upon a less surface than one inch of its track at a time, in the course of each revolution round its axis; hence it may be conceived to produce a kind of compensating effect, connected with the use of small stones, which prevents the tremour from being commu- nicated beyond the limited sphere of each particular block, and consequently, extending only a few inches. This system of paving was originally proposed for the Main-street of Lin- lithgow, forming part of the great western road from Edinburgh to Stirlingshire. Notice has since been taken of it in the Transactions of the Highland Society, vol. vi., and in Dr. Brew- ster's Encyclopaedia, under the article “Roads;” and a correct idea of the plan will at once be acquired by examining the following sketch. By using tracks of this description—giving the stones a proportionably broad bed—and laying thern upon § s º N. "a ag §s º s *ś a ſirm foundation, (which is indispensable,) we should have our streets, and the acclivities of our highways, rendered smooth and durable—avoiding, at the same time, the great expense and inconvenience of the common road, and the irksonne noise Specimens of these tracks have just been laid in some of the principal streets of Glasgow ; they have also been submitted to the trustees of the county of Edinburgh; and brought under the notice of some of the parishes of London. The tracks may be formed of granite, of 896 R O A R O A DICTIONARY OF MECHANICAL SCIENCE. whinstone, (i. e. green-stone or basalt,) or any of the hard varieties of rock capable of being hammer-dressed. Such materials abound in Scotland; in many parts of the north of Bngland, as far south as the approximating sources of the Tees and the Ribble; and in all the districts of Wales. sets of tracks may be laid, according to the nature or extent of the thoroughfare. Let us, for example, suppose that a street, measuring about thirty feet in breadth, be laid out in six com- partments, as shewn in the engraving, with a footpath on each side. causeway for the horse-paths of the city or town. The remain- ing three for the highway, are represented as laid with broken stones. The sides of the stones, where they come in contact with each other, are to be dressed so as to form a plain joint across the track, and dressed square, so as to touch throughout the whole surface of the joint. The wheel-track is to be flat, or without any groove. that carriages may move off and on with- out obstruction. The sides are to be dressed of the sloping form, shewn in the section of the road, but, excepting in the joints across the track and on the top, the stones are only to be hammer-dressed, or chipped after the usual manner. Great care will be necessary, as before noticed, in preparing a firm and compact foundation for the tracks. A stratum of gravel or stone chips, to the depth of three or four inches, laid in lime mortar, according to the nature of the soil, will answer in every case. The laying or building of street stones with mortar, is common in Bath, Paris, and other cities; and unless such a plan be resorted to, the best effects of this system will be lost to the public. In upholding roads or streets of this description, the inter- mediate spaces on which the horses go, will seldom require repair. aisler causeway has continued in good order for about fifteen years, and, with occasional repairs, may probably last double that period. From this we may conclude, that the tracks will continue for a period of many years. For, although the traffic upon them would be greater than upon the road or street gene- rally, yet it is curious to observe, that however spacious a road may be, carriages are found to go very much in particular lines, one after another; and therefore, the duration of aisler cause- way forms a pretty good criterion for judging of the compara- tive economy of the proposed wheel-tracks. With regard to the expense, we may notice, that in the vicinity of Edinburgh, the lineal yard of two of these tracks will cost about mine shil- lings, and consequently double of this sum for two sets, to suit carriages travelling in opposite directions. In the ordinary traffic of a city or public road, they may be estimated to last about fifteen years, or as long as three or four strata of com- mon road metal of eight inches in thickness. fore, will the comforts of the traveller and those around him be provided for, but the wear and tear of carriage wheels be pre- vented, and the direct economy of upholding the highways and streets be carried to an immense extent, by the adoption of this system. We are further of opinion, that this system of wheel- tracks is applicable in many situations, where iron railways would either be found too expensive, or where they cannot be introduced with propriety. During the last few years, public attention has been called to an improved system of road-making, introduced by Mr. Mc Adam. Its chief excellence consists in having a secure foundation or bed, rendered and kept as dry as possible. Over this, the rough materials, reduced to a given size, are laid in regular strata, in such a position that no water may settle on the surface, or penetrate beneath it, as the stones, being angu- lar, soon unite, and become compact by external and succes- sive pressure. This system of road-making answering every expectation in the country, has lately found its way into Lon- don, where in many of the streets the pavement has been torn up, and the stones have been broken by the hammer to the dimensions required. There can be no doubt that carriages run with more ease over roads thus constructed and hardened, than over a rough and unbroken pavement. But when the weather is wet, the streets are frequently covered with mud; and when dry, the inhabitants are much annoyed with clouds of dust. The ultimate advantages of this system in the city, remain yet to be discovered. place to place. One or more Three of these compartments are paved with ruble We have seen, in the example of Leith-walk, that Not only, there- Under the article RAILWAY, we have given a general, but brief account of this modern contrivance for aiding the facili- ties with which carriages heavily laden may be conducted from So far as general principle is concerned, all railways are the same; but, like most other inventions, they are susceptible of many improvements in subordinate particulars, among which, the following, by Mr. William James, of Thavies Inn, London, is deserving of special notice in this place, as being nearly allied to the preceding observations on roads. These improvements in the construction of rail-roads, or tram-ways, consist first in making the rails hollow, of whatever form cir- cumstances may render most eligible, the object of which is to reduce the quantity of the metal in the rail, and at the same time to retain the required strength; Secondly, in a method of produc- ing a rail with a double road-way, to be firmly fixed as the centre of two lines of rail-way, by which contrivance a saving of one rail in four will be effected; thirdly, in affording the means of con- ducting water, gas, or other fluid, from place to place, through the hollow tube of the rail; fourthly. in employing the hollow rail, as a trunk to receive ropes, chains, or rods passing from a standing engine, or other actuating machine, for the purpose of protecting these ropes or chains from external injury; and, fifthly, in attaching to such rails or tram-ways, certain rods, wheels, and endless chains, for the purpose of drawing or pro- pelling carriages along the said rail-way, which rods and wheels are to be actuated by means of a stationary steam-engine, or other stationary power. The hollow rails are either to be cast in a mould with a suitable core within, as castings are usu- ally done, or welded, rolled, or otherwise formed to the desired external shape, leaving a recess within ; or they may be made partly of metal tubes connected to stone or wooden sides or bottoms, so as to leave the internal part hollow.—This contri- vance of rendering the rails hollow may be adapted to any exter- nal form of rail, and will be found to save a very great portion of the expense of metal, and yet retain the same degree of strength as if solid. - The construction of a double line of road with three rails only, is to be effected by making the middle rail of sufficient breadth to allow two carriages to pass each other. Fig. 1, is a section of two lines of road con- structed of three hollow rails, that in the middle being broad enough to permit the two carriages to pass = freely. This contrivance may be Sextended to a treble line of road, to be formed of four rails instead of six, and so on, by which means a great saving of expense will accrue both in the cost of the rail, and the labour of laying down the lines. The advantages of the broad rail for reducing the number of lines, may be eſſected without adopting the hollow rail; these central lines may be constructed by joining together pieces of stone, which should be coated with plate iron, or planks of timber. The employment of such hollow rails for the passage of water, gas, or other fluid, from one place to another, may be advan- tageously resorted to, where such objects are desirable, without the expense of additional pipes or tubes; and these hollow rails may also be used with great advantage as trunks for con- ducting chains, rods, or ropes, passing from standing engines, or other machines employed for the purpose of drawing or pro- pelling carriages along the tram-way, which chains, rods, or ropes would by that means be protected from the weather and other external injuries. - The fifth head of the invention respects the attachment of rods, wheels, gear, and endless chains, to such rails or tram- º (? * ::::::::::: */?-NY Jºe (Z ==º % | |. 27 Az #5 : AºA. º: ****ſ-s “T, . * ways, for the purpose of drawing or propelling carriages there. on, by the agency of stationary engines. One mode of effecting R O A R. O & DICTIONARY OF MECHANICAL SCIENCE. 897 this purpose is shewn at fig. 2, which is a plan of a double line or rail-road, and fig. 3, an elevation of the same. Along the central line a. a, which is a double rail, a series of rods extend; their extremities being connected together by coupling boxes, ºº: ºrs «Kºjº º ſº.º.º. º º Yº..." º º ſºtºº &PN- %3E2. § @^ *T F- - WNS 2iSTJ, MSJ) * - _2}\D/ \º - +: ==######## #: łºśćff º::::::::::::::::::::º clutches, or other means, so as to enable the whole line of rods to turn as one axle, by the actuating power of a steam-engine, or other moving agent, situated at the extremity or in any con- venient part of the line. This power may be applied immedi- ately to the rods, or to the toothed wheel b, ander the rail-way, which wheel being made to revolve horizontally, and taking into endless screws or pinions upon the rods, cause them to turn. Below the rods the toothed wheel b is placed, which re- volving horizontally, works into the pinions c, fixed upon the rod. Supposing the power of the engine to be communicated to the toothed wheel b, by means of a lateral shaft and pinion d, the revolution of the wheel b would cause the rods a, a, a, to turn, and other wheels similar to b, being situated at certain distances apart under the rail-way, would also be made to re- volve in a horizontal direction, by means of the several pinions upon the central rods. On the same axle, and under the tooth- ed wheel b, is the large drum wheel e, which revolves with it; round this, and other similar drum wheels, situate on the axles of the toothed wheels, at certain distances apart, the endless chains f, f, f, f, are distended, and by the revolution of the drums these endless chains are carried round, supported upon anti-friction rollers, the endless chains being thus actuated, the carriages upon these roads are drawn forward by means of jointed arms g, g, extending from the sides of the carriages, which arms have claws at their lower extremities that drop into and take hold of the links of the chains, and thus by the pro- gress of the chains actuated as above described, the carriages are drawn or propelled along the rail-road; and in order to continue their progress past the breaks where the chains em- brace the drums, the arms, y, g, are set so far apart, that when the foremost arm falls out of action in passing the drum, the hinder arm has still hold of the chain, which continues to drive the carriage forward until the foremost arm has come into action with the next endless chain. Thus a succession of load- ed carriages may be advanced along one line of the road, and others returned on the opposite line, by the agency of the end- less chains, drums, toothed wheel, and line of rods, actuated by a steam engine, or other moving power, situate at the extremity of the line of rail-road, or any convenient places upon the line. Another mode of impelling carriages upon a similar double line of rails, is proposed by the patentee, varying in a slight degree === | -º-, e-º-e from the foregoing. Fig. 4, is a plan of such a line, and fig. 5, is a side view or elevation of the same; a, a, is a series of rods passing under the central rail connected together by coupling boxes as above described. At suitable distances apart on these rails are bevelled pinions, taking into other bevel pinions at the inner extremities of the cross shafts b, b, and, at the outer extremities of these cross shafts are rotatory cross arms c, c. On the outer side of each tram carriage a sort of ladder d, d, is affixed, by arms extending from the axle trees, and thus by the rotation of the central rods a, the cross shafts b, with their 91-2. W. E. as ºrw arms c, are made to turn ; and these cross arms c, taking into the ladders and pressing against the rollers of which the ladders aftſ; º-r- g £º º ź:#fff; are formed, by their rotation drive the carriage forward upon the rail-way. ROAD, or RoAD Stead, a bay or place of anchorage, at some distance from the shore, on the sea-coast, whither ships or ves- sels occasionally repair, to receive intelligence, orders, or ne- cessary supplies, or to wait for a more favourable wind, &c. A Good RoAdsteAD, is that which is protected from the reign- ing winds and the swell of the sea, has a good anchoring ground, and is a competent distance from the shore. - An Open RoAD, is one which is not sufficiently enclosed from the wind and sea. ROADER, or RoADstER, a vessel riding at anchor in a road, bay, or river. If a vessel under sail strike against any roader and damage her, the former is obliged by law to make good the damages sustained by the latter; roaders are careful to anchor at a competent distance from each other, so as not to intercept each other’s departure. ROASTING, in Metallurgy, the separation of volatile bodies from those which are more fixed. IROBANDS, or Rope Bands, pronounced Robins, short flat pieces of rope, having an eye worked in one end : they are used in pairs to tie the upper edges of the square sails to their respec- tive yards; the long leg passing over the yard two or three times round, and the short leg coming under is tied to it upon the yard. ROBBERY, is a felonious taking away of another man’s goods from his person or presence against his will, putting him in fear in order to steal the same. The value is immaterial.-If a man force another to part with his property, for the sake of preserving his character from the imputation of having been guilty of an unnatural crime, it will amount to a robbery, even though the party was under no apprehension of personal danger. If any thing is snatched suddenly from the head, hand, or person of any one, without any struggle on the part of the owner, or without any evidence of force or violence being ex- erted by the thief, it does not amount to robbery. But if any thing be broken or torn in consequence of the sudden seizure, it would be evidence of such force as would constitute a rob- bery; as where a part of a lady’s hair was torn away by snatching a diamond pin from her head, and an ear was torn by pulling off an ear-ring; each of these cases was deemed a robbery. By 7 George II. c. 21. If any person shall with any offensive weapon, assault, or by menaces, or in any forcible or violent manner, demand any money or goods, with a felonious intent to rob another, he shall be guilty of felony and shall be trans- ported for seven years. - If any person being out of prison shall commit any robbery, and afterwards discover two or more persons who shall commit any robbery, so as two or more shall be convicted, he shall have the king's pardon for all robberies he shall have committed before such discovery. - Highway robbery differs from robbery only in this, that there is a reward of £40 for the apprehending of the offender, and the horse which the robber rides is forfeited. - ROBERVAL, Giles PERson Ne, an eminent French mathe- matician, was born in 1602, and died in 1675, at the age of 73. ROBINS, BeNJAMIN, a distinguished English mathematician, was born at Bath, in 1707, and early discovered very superior talents, particularly for mathematical and philosophical sub- jects, which he afterwards pursued with great success. - ROBUR CA Roll NUM, the Royal Oak. See ConstellAtion. ROCK, a stony mass, forming a part of the substance of this globe. Rocks are divided into five classes: namely, 1. Primi- tive rocks.—2. Rocks of transition—3. Stratified or secondary rocks—4. Alluvial depositions—5. Volcanic rocks. 10 T - ... 898 R O C R O L DICTIONARY OF , MECHANICAL SCIENCE. A Half Tide Rock, a rock which appears above water at half ebb. ' * - . . . - - ROCK Work, any sort of work or design which is formed of fragments of rocks, or large stones, in gardens or pleasure grounds. - - - - . Rock Butter; in Mineralogy, a saline mineral formed in the fissures of rocks of alum slate. It is a kind of native alum, and feels greasy to the touch, and hence its name. RocK Cork, a flexible and somewhat elastic mineral, found in mineral veins. It is very soft, cracks when handled, but, breaks with difficulty ; it is so light as to swim, and is almost infusible with the blowpipe, so that it somewhat approximates to asbestos. - - Rock Crystal, the purest variety of the crystallized quartz. Rock Salt, a natural salt, of the same kind as common table salt. This useful mineral forms large beds and masses in many parts of the world, and even composes entire mountains. In this country, the salt mines of Cheshire are found very pro- ductive. . ROCKET, Sky. See FiReworks. Rocket, Congreve’s. This is a new species of war rockets, deriving their name from the inventor, Sir William Congreve. They differ from the common rocket, as well in their magnitude and construction, as in the powerful nature of their composi- tion; which is such, that without the incumbrance of any ord- nance, (the rocket containing the propelling power wholly within itself,) balls, shells, caseshot, and carcasses, may be projected to the distance of from 1000 to 3000 yards, which renders them a most efficacious species of artillery; as they may not only be employed in every case, and for every pur- pose, of the usual light and heavy ordnance, but they are available also in a variety of instances, in which the nature of the ground, or other impediments, prevent the effectual intro- duction of that arm. These rockets are of various dimensions, as well in length as in calibre, and are differently armed accord- ing as they are intended for the field, or for bombardment and conflagration; carrying, in the first instance, either shells or caseshot, which may be exploded at any part of their flight, spreading death and destruction amongst the columns of the enemy; and in the second, where they are intended for the destruction of buildings, shipping, stores, &c. they are armed with a peculiar species of composition, which never fails of destroying every combustible material with which it comes in contact. The latter are called carcass rockets, and were first used at Boulogne, their powers having been previously demon- strated in some experiments made at Woolwich, by Sir Wil- liam Congreve, in the presence of Mr. Pitt and several of the cabinet ministers, in the month of September, 1805. Sir Sidney Smith was ordered to command the expedition intended for this purpose ; but from the lateness of the season, it being near the end of November before the preparations were completed, nothing was done that year. In 1806, Sir William Congreve renewed his proposition for the attack of Boulogne by rockets, which was ordered to be put in execution after Lord Moira, at that time master-general of the ordnance, and Lord Howick, first lord of the admiralty, had satisfied themselves of the effica- cious nature of the weapons, from other experiments made again at Woolwich for that purpose. T he attack was accord- ingly made under the command of Commodore Owen, late in October, 1806; having been put off during the summer months, in consequence of the negociations for peace, at that time pend- ing between the courts of England and France. From this delay, however, instead of being conducted upon the grand scale at first intended, it became a mere desultory attack, in which not more than 200 rockets were fired. The town, how- ever, was set on fire by the first discharge, and continued burning for near two days; it was supposed also that some shipping were destroyed, but the greater part of the rockets certainly went over the basin into the town. After this, their first introduction as a military weapon, the carcass rockets have been used in almost every expedition, and in nearly all under the immediate inspection of their inventor. Their repu- tation was completely established at Copenhagen, where they did incredible execution: after the siege, they were ordered by Lord Chatham, the master-general of the ordnance, to be reported upon by a committee of field officers of artillery, who had witnessed their effect in that bombordment, and who pro- nounced them to be “a powerful auxiliary to the present system of artillery.” Indeed, the powers of this weapon are now esta- blished upon the best of all testimonies, the best of all crite- rions, the testimony of the enemy; a striking instance of which occurred at the siege of Flushing, where General Monnet, the French commandant, made a formal remonstrance to Lord | Chatham respecting the use of them in that bombardment; than which no better fact need be recorded of the effect they must have produced. If such, therefore, be the acknowledged power of the weapon in such an early stage of its progress, and only when a handful, as it were, were used, merely by way of expe- riment, under the inventor, with not more than twenty or thirty men to assist him, what may not be expected, when regularly organized in the service, and generally combined with the other implements of bombardment? * - - ROCKY, composed or abounding in stone, state, &c. as dis- tinguished from sandy, muddy, &c. ROD, or Pole, a long measure of 16% linear feet, or square measure of 372% square feet. • RODDEN CRIBs, in Agriculture, a sort of large wicker-work basket, for containing the hay or other fodder in farm yards. ROE, the spawn or seed of fish. That of male fishes is usu- ally distinguished by the name of soft roe, or milt, and that of the female by hard roe or spawn. ROEMER, OLAUs, a celebrated Danish mathematician, was born in Jutland in 1644, but spent several years at Paris, during which time he discovered the progressive motion of light by observations on the eclipses of Jupiter’s satellites; to him also we owe the theory of epicycloids, and their application to the teeth of wheels in machinery, which De La Hire afterwards wished to appropriate to himself. - ROESTONE, Oolite, in Mineralogy, so called, because it is composed of small round globules, supposed to resemble the roes of fishes, imbedded in a calcareous cement. These globules vary in size from a grain of mustard to that of a pea, and are evidently the result of crystallization. • * ROGATION Week, the week immediately preceding Whit Sunday, thus called from three fasts therein. - ROGUE, in Law, an idle and sturdy beggar, who, by ancient statutes, for the first offence was punished by whipping, and boring through the gristle of the right ear with a hot iron. For the second offence, if above the age of eighteen, he was to be put to death. Rogue’s March, in Military language, a peculiar beat of the drum, accompanied by fifes, when a soldier is drummed out of a regiment, or prostitutes are expelled a camp or garrison. Rogue’s Yarn, a name given to a rope-yarn, which is twisted in a contrary manner to the rest of a rope, and being tarred, if in a white rope, but white if in a tarred rope, is easily discovered; it is placed in the middle of the strand in all cables or cordage made for the king's service to distinguish them from the merchant's cordage. ROHAULT, JAMEs, a French Philosopher, was born in 1620; and very early became a great admirer and advocate of the philosophy of Descartes, in defence of which he wrote his “Phy- sics,” which was afterwards translated into Latin by Dr. Clark, with corrections, the best edition of which is 1718. ROLL, in Law, signifies a schedule or parchment which may be rolled up in the hand into the form of a pipe. ROLL, or Ro: LeR, is also a piece of wood, iron, brass, &c. of a cylindrical form, used in the construction of several ma- chines, and in several works and manufactures. ROLLE, M ic HEL, a French mathematician, born in 1652, and died in 1685, in his 53d year. - ROLLER, in Gunnery, is a round piece of wood, about nine inches in diameter, and four feet long, used in moving mortars from one place to another when near. Rollers are very numer- ous, and are applied to various purposes, in machinery, in agriculture, and in domestic life. RolleR, a cylindrical piece of timber fixed either horizon- tally or vertically in different parts of a ship, so as to revolve about an axis; it is used to prevent the cables, hawsers, and running rigging, from being chafed, by lessening the friction they would otherwise sustain. Rollers, are also moveable pieces of wood of the same figure, R. O. L. R o o 899 DICTIONARY OF MECHANICAL SCIENCE. which are occasionally placed under boats, pieces of timber, &c. in order to move them with greater facility. , ROLLING, that motion of a body, which is caused by its rectilinear motion being resisted, by the friction of some sur- face or otherwise; whereby its several parts come successively in contact with that plane or surface; such is the motion of a carriage wheel upon the ground, &c. See RotAtion. i ROLLING, the motion by which the ship rocks from side to side like a cradle, occasioned by the agitation of the sea. Roll- ing is accordingly a sort of revolution about an imaginary axis passing through the centre of gravity of a ship, so that the nearer the centre of gravity is to the keel, the more violent will be the rolling motion ; because the centre about which the vibrations are made, is placed so low in the bottom, that the resistance made by the keel to the volume of water which it displaces in rolling, bears very little proportion to the force of the vibration above the centre of gravity, the radius of which extends as high as the mast-heads. But if the centre of gravity is placed higher above the keel, the radius of vibration will not only be diminished, but an additional force to oppose the mo- tion of rolling will be communicated to that part of the ship’s bottom which is below the centre of gravity. Many fatal dis- asters have arisen to ships from their violent rolling, as the loss of the masts, loosening the cannon, and straining the decks and sides; it is therefore particularly necessary to guard against it as much as possible, not only in the construction of the bottom, but by causing the centre of gravity of the ship to fall as near the load-water line as possible, which can only be effected by a judicious arrangement of the ballast or cargo. ROLLING MACHINE, for making the brass mouldings in fenders, and in the brass work of grates. The invention of this machine originated in a cause, which has since operated in producing many others, namely, the reduction of prices at the peace. The usual mode of raising the brass mouldings pre- vious to that period, was by hammering and pressing, which being very laborious as well as tedious, Mr. M'Kinnon turned his attention to the invention of some other mode by which the operation might be rendered more easy and less expensive. The price of the manufactured article had fallen so low, and the wages of the workmen not having suſpered a corresponding depression, rendered this almost necessary; and, accordingly, after some trials, the present machine was constructed, which answers the purpose most perfectly. The invention is entirely his own; but a knowledge of its construction, (which is abun- dantly simple,) having been communicated to some individuals through the medium of workmen who had been with him, it is now generally known to manufacturers in the line, and we therefore consider it unnecessary to withhold it from the public. ... Description of the Machine.—Fig. 1. A the bottom, and B B the sides or uprights of the frame; g.g., two moveable rollers, and d d guides, of which there are two on each side of the Fig. 1. |L rollers; see fig. 2. When the machine is to be used, it is placed on an iron stand, two feet and a half high, and fastened to the floor. The screws c c are then screwed upwards, to separate the rollers so as to admit the flat plate of brass to be moulded. The end of the plate being then inserted between the rollers, the screws c e are screwed down, and the rollers turned by handles attached to the square projecting ends h h. By this motion, the brass will acquire the same moulding as is formed upon the rollers, of which there are a great variety of patterns. Should the moulding be not completely formed after having gone once through, it is only necessary to screw the rollers tighter together, and pass it through until the accurate form be obtained. The rollers in the drawing are used chiefly for the ornamental brass work of grates. When fenders are to be made, one of the uprights, B, at the left hand, fig. 1, is to be removed to the end of the sole plate, to admit the fenders. The operation of making these, being in every respect the same as described above, it is unnecessary to be more minute. ROLLING MILL, in Metallurgy, is a mill for reducing masses of iron, copper, or other metals, into even parallel bars, or thin plates. This is effected by passing the metal, whilst red hot, between two cylindrical rollers of steel, put in motion by the mill, and being so mounted in a strong metal frame that they cannot recede from each other, they can press the metal which is passed between them, and reduce it to a thickness equal to the space between their surfaces. Rolling mills have not been in general use until within about ninety years. Rolli NG Tackle, a purchase occasionally fixed on the wea- ther quarter of a yard, in order to confine it, and prevent its chafing when a ship rolls heavily. - ROMAIN, in Agriculture, the name of a plant cultivated in the fields, and called by English farmers French vetches. ROMAN CATHOLICS, in Church History, a name given to those Christians who believe the doctrines and submit to the discipline of the church of Rome. They are also called Papists, from papa, father, the pope. ROMANCE, a fabulous relation of certain intrigues and adventures in love and gallantry, invented to entertain the frivolous and fickle among readers. Sometimes they are in- structive, but more generally they are delusive, by representing as true, what has no real existence. . ROOD, a square measure, the fourth of an acre. See Me Asure. RO OF. See Hous E. ROOK, in Ornithology, a well-known bird of the crow kind. Many curious particulars belong to their natural history. ROOKERY, in rural economy, a term applied to a nursery of rooks, where they build their nests and collect in large num- bers. Rookery is also applied, in cant language, to a house in which females of abandoned character associate. ROOM, at Sea, a name given to some particular apartment in a ship, as, the Cook Room. See the article GAlley. The Bread Room, is in the aftermost part of the hold, being parti- tioned off and properly lined, to receive the bread, and keep it dry. Gun Room ; Light Room. Steward Room, the apartment where the steward weighs, measures, and serves out the pro- visions to the ship's company; it is usually situated on the orlop deck, adjoining to the bread-room. Sail Rooms, are places on the orlop deck, enclosed for the reception of the sails; they are distinguished according to their relative situation, as, the fore-sail room, the after sail-room. Spirit Room, a space in the after part of a ship's hold, set apart for the reception of wine, brandy, &c. Ward Roo M, a room over the gun-room in ships of war, where the lieutenants and other principal officers sleep and mess. ROOT, in Arithmetic and Algebra, denotes a quantity, which being multiplied a certain number of times into itself, produces another number, called a power, and of which power the origi- nal quantity is called the root. Roots are distinguished into square roots, cube roots, biquadratic roots, &c. or into 2d, 3d, 4th, 5th, &c. roots, which depend upon the number of multipli- cations necessary to generate the proposed power. If one mul- tiplication only is necessary, or if two equal factors are multi- plied together, it is called the square or second root; if three, the cube or third root; if four, the biquadratic or fourth root, &c. : thus 8 is the square root of 64; 4 is the cube root of 64; 2 is the sixth root of 64, &c. &c. For the extraction of the roots of numbers, see ExTRACTION. - - Root, in Mathematics, a quantity considered as the basis or foundation of higher power; or one which, being multiplied 900 R o S R O T DICTIONARY OF MECHANICAL SCIENCE. into itself any number of times, produces a square, cubic, biqua- dratic, &c. quantity; called the second, third, fourth, &c. power of the root, or quantity so multiplied into itself. . Root, in vegetable physiology, is an important part of the vegetable body, being the basis of the whole, and what is first produced from the seed when evolved by the process of germi- nation. Its uses are to fix the plant in the ground, and to derive nourishment for its support. ROPES, are a general name given to all sorts of cordage above one inch in circumference, used in rigging a ship. Ropes are of two descriptions, viz. Cable-laid, which are composed of nine strands, the three great strands containing each three small strands; and Hawse-laid, which are made with three strands, each composed of a certain number of rope-yarns in proportion to its required thickness. RoPE Yarn, the smallest and simplest part of any rope, being one of the threads of which a strand is composed, so that the size of the latter, and of the rope in which it is twisted, are de- termined by the number of rope-yarns. ROQUET, in Zöology, the name of a species of American lizard, small in size, of a reddish brown colour, variegated with black and yellow spots. Its eyes are particularly vivid and sparkling. te ROSA, the Rose, a fragrant flower, too well known to require any description in this work. The species are exceedingly InUILT162 rou S, ROSADE, a kind of liquor prepared of pounded almonds and milk, mixed with clarified sugar. ROSARY, in the Romish church, is a chaplet consisting of five or fifteen decades of beads, to direct the recitation of so many Ave Maria's in honour of the Virgin. It also denotes a particular mass or form of devotion addressed to the Virgin, to which the chaplet of that name is accommodated. ROSE ENGINE, a machine used for turning articles in wood like a common lathe, with additional properties, by which the surface of the wood that has been turned can afterwards be engraved with a great variety of patterns of curved lines. These, in general, are denominated from the French rosette, from a distant resemblance which they have to a full-blown rose, and hence, the machine is called a rose engine. Its con- struction is remarkably curious. ROSEWOOD, How to make Imitations of.-Brush the wood over with a strong decoction of logwood, while hot; repeat this process three or four times; put a quantity of iron filings amongst vinegar; then, with a flat open brush, made with a piece of cane, bruised at the end or split with a knife, apply the solution of iron filings and vinegar to the wood, in such a man- ner as to produce the fibres of the wood required. After it is dry, the wood must be polished with turpentine and bees-wax. ROSICRUSIANS, a sect of hermetical philosophers, first noticed in Germany in the fourteenth century. An affected secrecy gave them fame, especially as they pretended to have discovered the philosopher's stone. But when it was proved they had nothing to conceal, they sunk into neglect, and finally into contempt. ROSIN. See ResiN. ROSMARUS, the name of an animal; sometimes called the Sea Horse, but more commonly the Mase. ROSMARINUS, Rose MARY, a genus of the monogynia order, in the diandria class of plants, and in the natural method rank- ing under the 42d order, verticillatae. The corolla is unequal, with its upper lip bipartite; the filaments are long, curved, and simple, each having a small dent. There are two species. ROSOMACHA, in Zöology, a name given by the Russians to the glutton. Claus says, they are taken by the hunters chiefly for their skins, which are much esteemed by persons of fortune, for robes, the fur being naturally variegated with bright colours resembling flowers. ROSTRA, in Antiquity, a part of the Roman Forum, in which orations, pleadings, funeral harangues, &c. were deli- vered. The Rostrum, taken as a sort of chapel out of the Forum, was furnished with an eminence on which the orators stood to speak, and to this elevation the name was more parti- cularly applied, Hence, the term Rostrum has been transfer- red to pulpits, platforms, and stages, in the present day. ROSTRUM, in Ornithology, literally denotes the beak of a *. bird, and is applied to the hard and horny edges of the bill, which answer to the mandible in quadrupeds. Hence the word is figuratively applied to the prow or head of a ship. Rostrum is also used to designate an instrument with which paper is ruled for musical compositions. Rostrum, in Che- mistry, signifies the nose or beak of the common alembic, which conveys the liquor distilled into the receiver. In Surgery, Rostrum is a sort of crooked scissars used for the dilation of wounds. It likewise means the piece of flesh situated between the margins of a hare-lip. In Botany, Rostrum expresses the beak of a seed, or rather the elongation of the apex of a naked seed. - ROT, in rural economy, a sort of putrid decay taking place gradually, in various substances, either from the effects of moisture, or other causes. RoT, is also a disease incident to sheep and other animals, in which the liver and lungs are affected, and a tendency to dropsy is produced. It is chiefly connected with moisture, but its causes have not yet been satisfactorily explored. Rot, Dry. See DRY Rot. - RoT, in hops, is a disease in the crops of this valuable article, very similar to mouldiness. ROTA, in Mechanics. See Wheei,. RoTA Aristotelica, or Aristotle's Wheel, denotes a problem in mechanics proposed by Aristotle concerning the motion of a coach wheel; viz. that the nave of a wheel describes by its mo- tion, (supposing it to roll along a plane,) a line of the same length as the circumference by its motion on the ground ; which was long considered paradoxical, nor was it clearly understood till M. Meyran, a Frenchman, sent a satisfactory solution of it to the Academy of Sciences, the principle of which is, that each point of the circumference of the nave, as it approaches the plane, is drawn forward over a space greater than itself, whereas every point and part of the circumference of the wheel passes over a space exactly equal to itself. ROTATION, the motion of the different parts of a solid body about an axis called the axis of rotation, being thus dis- tinguished from the progressive motion of a body about some distant point or centre ; thus the diurnal motion of the earth is a motion of rotation, but its annual motion one of revo- lution. When a solid body turns round an axis, retaining its shape and dimensions unaltered, every particle is actually describing a circle round this axis, which axis passes through the centre of the circle, and is perpendicular to its plane. Moreover, in any instant of the motion the particle is moving at right angles with the radius vector, or line joining it with its centre of rotation; therefore, in order to ascertain the direction of any particle, we may draw a line from that par- ticle perpendicular to the axis of rotation. This line will be in the plane of the circle of rotation of that particle, and will be its radius vector, and a line drawn from the particle perpendicular to its radius vector, will be a tangent to the circle of rotation, and will represent the direction of the motion of this particle. The whole body being supposed to turn together, it is evident, that when it has made one com- plete rotation, each point has described the circumference of a circle, and the whole paths of the different particles will be in the ratio of these circumferences, and therefore of their radii; and this is also true of any portion of such cir- cumferences, that is, the velocities of the different particles are proportional to their radii vectores, or to their distances from the axis of rotation. And all these motions are in pa- rallel planes, to which the axis of rotation is perpendicular. Hence it follows, that when we compare the rotation of dif- ferent bodies in respect of velocity, it is evident that it can- not be done by directly comparing the velocity of any par- ticle in one of the bodies with that of any particle of the other; for as all the particles of each have different veloci- ties, this comparison can establish no ratio. But we may familiarly compare such motions by the number of complete turns which they make in any equal portions of time. There- fore as the length or number of feet described by a body in rectilinear motion is a proper measure of its progressive ve- locity, so the angle described by any particle of a whirling body is a proper measure of its velocity of rotation ; and in this man- ner may the rotation of two or more bodies be compared, and R O T R O U 901 DICTION ARY OF MECHANICAL SCIENCE. this velocity is with propriety called the angular velocity. In what is stated above, we have had principally in view a fixed and permanent axis of rotation, the body not being sup- posed at liberty to revolve about any other ; but it is obvious that if any force is impressed upon a body, or system of bodies, in free space, (unless that force be exerted in a direction passing through the centre of gravity of the system) a rotatory motion will ensue about an axis passing through the centre of gravity of the system; and the centre about wbich this motion is per- formed, is called the centre of spontaneous rotation. A body may begin to revolve on any line as an axis that passes through the centre of gravity, but it will not continue to revolve permanently about that axis unless the opposite centrifugal forces exactly balance each other. Thus a homogeneous sphere may revolve permanently on any diameter, because the opposite parts of the solid, being in every direction equal and similar, the oppo- site centrifugal forces must be equal ; so that no force has a tendency to change the position of the axis. Hence also a ho- mogeneous cylinder may revolve permanently about the line which is its geometric axis; as it may also about any line that bisects that axis at right angles, but it can revolve permanently about no other line, because then the centrifugal forces could not be equal; and the same is true to any solid of rotation. In every body, however irregular, there are three permanent axes of rotation, at right angles to each other, on any one of which when the body revolves, the opposite centrifugal force exactly balances, and therefore the rotation becomes permanent. These three axes have also this remarkable property, that the momentum of inertia, with respect to any of them, is either a maximum or a minimum ; that is, either greater or less than if the body revolved about any other axis. This curious theorem was first proposed by Segner in 1755, and first demonstrated by Albert Euler, in a memoir presented to the academy of sciences at Paris in 1766. . At present we have considered those cases of rotation that are produced by a force impressed upon a body, either as supported on a fixed axis, about which, therefore, that’system must necessa- rily revolve; or as in free space, in which case the system acquires a spontaneous centre of rotation, and finally a permanent axis of rotation : but there are other circumstances which will produce a rotatory motion, that are not included in either of the above, but which it will be proper to mention before we conclude this article, such are those which arise from a body descending down an inclined plane, having a ribbon or cord wound about it, one end of which is fixed at the upper part of the plane, which by pre- venting the body sliding freely, causes a rotatory motion: the same effect also follows from the friction of the body against the plane; and the same may be imagined when there is no plane but the body left to fall freely, except so far as the cord wound about it shall produce a rotatory motion in its descent. We shall not attempt the investigation of these cases, but merely state the results that have been obtained, and must refer the reader for the former to the several treatises on dynamics re- fered to in various parts of this volume, and to the articles DYNAMI cs and MechANics. Let a body have a cord wound abou. it, either at its circumference or any other part, as BC, having one end fixed at a point above, as at A ; then if the body be left to descend by the action of gravity, it "will acquire a motion of rotation by the unwinding of the cord; and the space actually descended by the body in this case, will be to the space descended in the same time when falling freely, as C G to CO ; O and G representing the centres of oscilla- tion and gyration, when the point of suspension is at C: and the weight of the body will be to the tension of the cord, as CO to C G ; and the same ratios have place when the body descends down an inclined plane : the forces which ge- nerate the motion being both decreased in the same ratio. The force by which spheres, cylinders, &c. are caused to revolve as they move down an inclined plane (instead of sliding), is the adiº, of their surfaces, occasioned by their pressure against | |A the plane; this pressure is part of the weight of the body, for this weight being resolved into its component parts, one in the direction of the plane, the other perpendicular to it; the latter is the, force of the pressure; and which while the same body rolls down the plane, will be expressed by the cosine of the plane's elevation. Hence, since the cosine decreases, while the arc or angle of elevation arrives at a certain magnitude, the adhesion may become less than what is necessary to make the circumference of a body revolve fast enough, and in this case it will proceed partly by sliding and partly by rolling; but the angle at which this circumstance takes place, will evidently depend upon the degree of adhesion between the surfaces of the body and plane. This, however, will never happen, if the rotation is produced by the unwinding of a ribbon, and it is on this latter supposition that the following particular cases are deduced. Let W be the weight of the body, s the space de- scended by a heavy body, falling freely, or sliding freely down a plane, then the spaces described by rotation in the same time, by the following bodies, will be in these proportions. 1. A hollow cylinder, or cylindrical surface S – 3 s, tension = & W. 2. A solid cylinder S = 3 s, tension = } W. 3. A spheric surface S = }s, tension = 3 W. 4. A solid sphere S = #s, tension = # W. ROTATORY Motion, when produced by a reciprocating motion, requires some contrivance to render it uniform, or nearly so. The usual method of equalizing is, by attaching a fly wheel to some part of the machinery; but Mr. Arthur Woolf has invented an apparatus to be substituted for the fly in steam- engines, which possesses the advantage of equalizing the motion, with the property of being stopped, and set to work at any part of the stroke. - In fig. 1, A represents part of the engine beam ; B, the connecting rod; C, the crank arm ; D, a cog wheel, working into another cog wheel E, of half the size ; F, a crank arm on the shaft of the small wheel ; G, a cylinder closed at bottom, in which a solid or unper- forated piston moves, leav- ing a vacuum beneath. This acts simply instead of a weight on the crank F, by the constant pressure of the atmosphere ; and the dia- meter of the piston must be such as nearly to equal one- third of the power of the engine. - In fig. 2, the outer circle is the line described by the crank ; the circumference of the inner circle is equal to twice the diameter of the outer, and the square has the same circum- ference: this last exhibits the inequality still remaining, which by this method is reduced to about one-fifth ; but by the assist- ance of a small fly on the second motion, the effect will become nearly the same as that of a rotative engine, with the advantages here mentioned. The same motion may be applied to a pump. but in this case the two cranks must be horizontal at the same time. ROTONDO, or Rotu NDo, in Architecture, an appellation given to any building that is round both within and without, whether it is a church, a saloon, or the like. ROTTEN Stone, a decomposed stone used for polishing. ROUBBIE, a coin of Turkey, value 1s. 5}d. Sterling. ROUCOU, otherwise called 'ANNotto, is a red dye formed in masses from the pellicles of the seeds of an American tree. That which we commonly have is moderately hard and dry, of a brown colour on the outside, and of a dull red within. Labat informs us, that the Indians prepare a dye of this article far superior to that which we have. It is of a bright shining red colour, almost equal to carmine. * ROUEN, in Agriculture, a term that signifies aftergrass, or the hay made from it. 10 U. 902 R. O. W. R U L DICTIONARY OF MECHANICAL SCIENCE. ROUGH CAST WASH, in rural economy, is a sort of liquid wash laid over the surfaces of outside walls, or buildings, to preserve and ornament them. It consists of four parts of pounded lime, three of sand, two of pounded wood ashes, and one of the scoria of iron, mixed intimately together, and made sufficiently thin to be applied by a brush. When dry, it gives the wall the appearance of new Portland stone, and affords an excellent protection against the severity of the weather. ROUGH TREE, a name given in merchant ships to any mast, yard, or boom, placed as a rail or fence above the ship's side, from the quarter deck to the forecastle; it is, however, with more propriety applied to any mast, &c., which remaining rough and unfinished, is placed in that situation. ROUND, in a Military sense, signifies a walk which some officer, attended by a party of soldiers, takes in a fortified place around the ramparts, in the night-time, in order to see that the sentries are watchful, and that every thing is in order. ROUND House, a name given in East Indiamen, and other large merchant ships, to a cabin or apartment built on the after part of the quarter deck; and having the poop for its roof, this apartment is frequently called the coach, in ships of war. Round House, is also a name given on board ships of war to certain necessaries built near the head, for the use of the mates, midshipmen, and warrant officers. ROUNDELAY, an antiquated kind of poem, of peculia metre, at present but little known in this country. - ROUNDING, old ropes wound firmly and closely about that part of a cable which lies in the hawse, or athwart the stem $.c. It is used to prevent the cable from being chafcd. Round ING In, generally implies the act of pulling upon any Alack rope which passes through one or more blocks in a direc- tion nearly horizontal, and is particularly applied to the braces as, “Round in the weather braces.” It is apparently derived from the circular motion of the rope about the sheave or pulley through which it passes. Rounding up, is used nearly in the same sense, only that it is expressed of a tackle which hangs in a perpendicular direction, without sustaining or hoisting any weighty body, and is opposed to over-hauling. Round Turn, the situation of the two cables of a ship, which when moved has swung the wrong way three times successively. Round Turm, is also the passing a rope once round a timber head, &c. in order to bold on. ROUSE, To, is to pull together upon a cable, &c. without the assistance of tackles, capstans, or other mechanical powers. ROUT, in Law, is an assemblage of more than three per- sons going forcibly to commit an unlawful act, even though they do not actually execute their intentions. To make advances towards it, is a rout; to execute their designs, is a riet. ROVER, a pirate or freebooter. - ROW Culture, in Agriculture, is that method in which th crops are sown in drills, and afterwards cultivated according to that system. ROW, To, to impel a boat or vessel along the surface of the water by oars, which are managed in a direction nearly hori- zontal. - - Row Dry, the order to those who row, not to splash water into the boat with their oars. Row Locks, those parts of a gunwale, or upper edge of a boat's side, whereon the oars rest in the exercise of rowing. Row Galley, a long, low, flat-built vessel, sometimes fur- mished with a deck, and navigated with sails and oars particu- larly in the Mediterranean. Row CD of All, the order for the rowers to cease and to lay their oars in the boat. - Row ERs, the persons by whom the oars are managed. Row Forts, little square holes cut in the sides of small ves- sels of war, parallel to the surface of the water, for the purpose of rowing them in a calm. ROWETY Woc L, a term applied to the young wool of some sheep, which rises below the old fleece. ROWLEY RAG, in Mineralogy, a basaltic stone from Row- ley, near Dudley, in Staffordshire. It is used for polishing some of the manufactures of Birmingham, and has been strongly recommended for grinding the specula of reflecting telescopes." ROWNING, John, an ingenious English mathematician was born about the year 1700, and died in 1771. 5 chants met in Lombard-street. ROYAL, the name of a sail spread immediately above the top-gallant sail, to whose yard-arms the lower corners of it are attached : it is sometimes termed top-gallant royal, and is never used but in fine weather. ROYAL EXCHANGE, the burse or meeting-place of the merchants in London. It was built in 1566, at the charge of Sir Thomas Gresham, and in a solemn manner by herald, with sound of trumpet, in the presence of Queen Elizabeth, pro- claimed “The Royal Exchange.” Prior to this time the mer- In the great fire in 1666, it was totally consumed, but was soon raised again with still greater magnificence, at an expense of £50,000. Roy AL Society, in London, is an academy, or body of persons eminent for learning and scientific knowledge, instituted by Charles II. for the promoting of natural knowledge. RUBIFYING, in Chemistry, the act of turning any thing red by the force of fire. Thus, red arsenic is common white arse- nic rubified by a mixture of sulphur and copper. RUBIGO, a disease in corn when growing, commonly called mildew. For this, various causes have been assigned, but the | real source of this agricultural malady still remains partially unexplored. - RUBIN of ANti Mony, in Chemistry, is a kind of liver of antimony, made with equal parts of crude antimony and nitre detonated together, to which is afterwards added an equal quantity of common salt. - RUBLE, a Russian coin, those of 1764, value 3s. 3d. ; and of 1801, value 2s. 9%d. sterling. RUBRIC, in the Canon Law, signifies a title or article in certain ancient law books; thus called because written, as the titles of the chapters of our ancient Bibles are, in red letters. Rubrics also denote the rules and directions given at the begin- ning and in the course of the liturgy, for the order and manner in which the several parts of the office are to be performed. There are general rubrics, special rubrics, a rubric for the communion, &c. In the Romish missal and breviary are rubrics for matins, for lauds, for translations, beatifications, &c. RUBUS, the Raspberry, a genus of the polygamia order, in the icosandria class of plants; and in the natural order ranking under the 35th order, senticosae. The calix is quinquefied, the petals five : the berry consisting of monospermous acini, or pulpy grains. There re 32 species. RUBY, a genus of precious stones of various colours; as 1. Of a deep red colour, inclining a little to purple; the carbuncle of Pliny. 2. The spinell, of the colour of a bright corn poppy flower. 3, The balass, or pale red, inclining to violet. 4. The rubi cell, of a reddish yellow. RUCTATION, in Medicine, belching, an involuntary dis- charge of flatus from the stomach. This is a symptom of indi- gestion. Persons liable to this complaint should carefully avoid fermentive food, in which class all vegetables are included. RUDDER, in Navigation, a piece of timber turning on hinges in the stern of the ship, and which, opposing sometimes one side to the water and sometimes another, turns or directs the vessel this way or that." See H E LM. RUDDOCK, the name of a well-known bird, Robin red breast. RUDIMENTS, the first principles or grounds of any art or science, sometimes called elements. - RUDOLPHINE TABLEs, a celebrated set of astronomical tables published by Kepler, and thus entitled in honour of the emperor, Rudolph, or Rudolphus. - RUE, in Medicine, a plant well known, the leaves of which have a strong ungrateful odour, and a bitter, hot, penetrating taste. If much handled, they are so acrid as to irritate and inflame the skin. In the Materia Medica rue is of great value, being used in many ways, and applied to various purposes. RUININE OIL, the oil of the Palma Christi, which is very common in the West Indies, and is used by the common people in lamps. It is delicate, sweet, and transparent; its leaves are one of the grand remedies among the negroes; and when bruised and applied to the head, they are thought to be an infallible cure for the head-ache. - RUINS, a term more particularly applied to magnificent buildings fallen to decay; such as Babylon, Persepolis, &c. RULE, or RULeR, an instrument of wood or metal with seve- | ral lines delineated on it, of great use in practical mensuration. R U L R U L 903 DICTIONARY OF MECHANICAL SCIENCE, RULE of THRee, in Arithmetic, called by some authors the Golden Rule, is an appellation of the doctrine of proportion to arithmetical purposes, and is divided into two cases, simple and compound; now frequently termed Simple and Compound Propor- {101. Simple Rule of Three, or Simple Proportion, is, when from three given quantities, a fourth is required to be found, that shall have the same proportion to the given quantity of the same name, as one of the other quantities has to that of the same name with itself. This rule is, by some authors divided into two cases; viz. The Rule of Three. Direct, and The Rule of Three Inverse; but this distinction is unnecessary, and the two cases are now generally given under one head by all our best modern authors; but as they are still retained by others, it will not be amiss to point out the distinction. . The Rule of Three Direct, is when more requires more, or less requires less, as in this example: If 3 men will perform a piece 3f work, as for instance, dig a trench 48 yards long in a certain time; how many yards will 12 men dig in the same time ! where it is obvious, that the more men there are employed, the more work will they perform, and therefore, in this instance, more requires more. Again, if 6 men dig 48 yards in a given time, how much will 3 men dig in the same time 2 Here less requires less, for the less men there are employed, the less will be the work that is performed by them; and all questions that are in this class are said to be in the Rule of Three Direct. The Iłule of Three Inverse, is, when more requires less, or less requires more. As in this, if 6 men dig a certain quantity of trench in 14 hours; how many hours will it require for 12 men to dig the same quantity ? Or thus, if 6 men perform a piece of work in 7 hours; how long will three men be in performing the same work : These cases are both in the Inverse Rule, for in the first more requires less, that is, 12 men being more than 6 they will require less time to perform the same work; and in the latter, the number of men being less, they will require a longer time. All questions of this class are said to be in the Rule of Three:Inverse. These two cases, however, as we before observed, may be classed under one general rule, as follows:– Rule.—Of the three given terms, set down that which is of the same kind with the answer towards the right hand; and then consider, from the nature of the question, whether the answer will be more or less than this term. Then if the answer is to be greater, place the less of the other two terms on the left, and the remaining term in the middle ; but if it is to be less, place the greater of these two terms on the left, and the less in the middle ; and in both cases, multiply the second and third terms together, and divide the product by the first term for the answer, which will always be of the same denomination as the third term. Note 1. If the first and second terms consist of different deno- minations, reduce them both to the same ; and if the third term be a compound number, it is generally more convenient to re- duce it to the lowest denomination contained in it.—Note 2. The same rule is applicable whether the given quantities to be inte- gral, fractional, or decimal. Central RULe. See Centra L RULE. Sliding RULE, a mathematical instrument serving to perform computations in gauging, measuring, &c. without the use of compasses, merely by the sliding of the parts of the instrument one by another, the lines and divisions of which give the answer or amount by inspection. This instrumentis variously contrived, and applied to different authors, particularly Gunter, Partridge, Hunt, Everard, and Coggeshall, but the more usual and useful ones are those of the two latter. - Everard's Sliding RULE, is chiefly used in cask gauging. It is commonly made of box, 12 inches long, 1 inch broad, and # of an inch thick. It consists of three parts, viz. the stock just mentioned, and two thin slips of the same length, slid- ing in small grooves in two opposite sides of the stock; conse- quently when both these pieces are drawn out to their full ex- tent, the instrument is 3 feet long. On the first broad face of the instrument are four logarithmic lines in numbers, for the properties, &c. of which, see GUNTER’s Line. The first marked A, consisting of two radii 1, 2, 3, 4, 5, 6, 7, 8, 9, 1; and then 2, 3, 4, 5, &c. to 10. On this line are four brass centre pins, two in each radius: one in each of them being marked M. B., for malt bushel, is set at 215042, the number of cubic inches in a malt bushel; the other two are marked with A, for ale gallon, at 282, the number of cubic inches in an ale gallon. The 2d and 3d lines of numbers are on the sliding pieces, and are ex- actly the same with the first: but they are distinguished by the letter B. In the first radius is a dot marked S1, at '707, the side of a square inscribed in a circle whose diameter is 1. Another dot marked Sc. stands at 886, the side of a square equal to the area of the same circle. A third dot, marked W, is at 231, the cubic inches in a wine gallon. And a fourth mark– ed C, at 314, the circumference of the circle, whose diameter is 1. The fourth line of numbers, marked MD, to signify, malt depth, is a broken line of two radii, numbered 2, 10, 9,8,7,6, 5, 4, 3, 2, 1, 9, 8, 7, &c.; the number 1, being set directly against M B on the first radius. . On the second broad face marked c d, are several lines; as first a line marked D, and numbered 1, 2, 3, &c. to 10. On this line are four centre pins, the first marked W G, for wine gage, is at 17:15, the gage point for wine gallons being the dia- meter of a cylinder whose height is one inch, and content 231 cubic inches, or a wine gallon. The second centre pin marked A G, for ale gage, is at 1895, the like diameter for an ale gal- lon. The third mark MS, for malt square, is at 463, the square root of 2150'42, or the side of a square whose content is equal to the number of inches in a solid bushel. And the fourth marked M R, for malt round, is at 52:32, the diameter of a cylinder or bushel, the area of whose base is.the same 2150'42, the inches in a bushel. 2dly. Two lines of numbers upon the sliding piece, on the other side marked C. On these are two dots, the one marked c, at 0795, the area of a circle whose circumference is 1 ; and the other marked d, at 785, the area of the circle whose diameter is 1. 3dly. Two lines of segments, each numbered 1, 2, 3, to 100, the first for finding the ullage of a cask, taken as the middle frustum of a spheroid, lying with its axis parallel to the horizon; and the other for finding the ullage of a cask Standing. Again, on one of the narrow sides noted c, are first a line of inches, numbered 1, 2, 3, &c. to 12, each subdivided into 10 equal parts. 2dly. A line by which, with that of inches, we find a mean diameter for a cask in the figure of the middle frustum of a spheroid; it is marked spheroid, and numbered 1, 2, 3, &c. to 7. 3dly. A line for finding the mean diameter of a cask, in the form of the middle frustum of a parabolic spin- dle, which gaugers call the second variety of casks; it is there- fore marked second variety, and is numbered 1, 2, 3, &c. 4thly. A line by which is found the mean diameter of a cask of the third variety, consisting of the frustums of two parabolic co- noids, abutting on a common base, it is therefore marked third variety, and is numbered 1, 2, 3, &c. On the other norrow face marked f, are, 1st, a line divided into one hundred equal parts, marked FM. 2ndly. A line of inches, like that before mention- ed; marked I.M. 3dly. A line for finding the mean diameter of the fourth variety of casks, which is formed of the frustums of two cones, abutting on a common base. It is numbered 1, 2, 3, &c. and marked FC, for frustum of a cone. On the back side of the two sliding pieces is a line of inches, from 12 to 36, for the whole extent of the 3 feet, when the pieces are put end- ways; and against that, the correspondent gallons and 100th parts that any small tub or the like open vessel will contain at 1 inch deep. For the varions uses of this instrument, see the authors mentioned above, and most writers on gauging. Coggeshall's Sliding RULE, is chiefly used in measuring the superficies and solidity of timber, masonry, brick-work, &c. This consists of two parts, each a foot long, which are united together in various ways. Sometimes they are made to slide by one another like glaziers' rulers: sometimes a groove is made in the side of a common two-foot rule, and a thin sliding piece on one side, and Coggeshall's lines added on that side; thus forming the common or carpenter's rule; and sometimes one of the two rulers is made to slide in a groove made in the side of the other, On the sliding side of the rule are four lines of numbers, three of which are double, that is, are lines of two radii, and the fourth is a single broken line of numbers. The first three marked A, B, C, are figured 1, 2, 3, &c. to 9: then 1, 2, 3, &c. to 10; the construction and use of them being the same as those on Everard’s sliding rule. The single line called the girt line, and marked D, whose radius is equal to two radii of any of the other lines, is broken for the easier measuring of 904. R Y E R U P DICTIONARY OF MECHANICAL SCIENCE. timber, and figured 4, 5, 6, 7, 8, 9, 10, 20, 30, &c. From 4 to 5 it is divided into 10 parts, and each 10th subdivided into 2, and so on from 5 to 10, &c. On the back side of the rule, are, 1st. a line of inch measure, from 1 to 12, each inch being divided and subdivided. 2ndly. A line of foot measure consisting of one foot divided into 100 equal parts, and figured 10, 20, 30, &c. The back side of the sliding piece is divided into inches, halves, &c. and figured from 12 to 24; so that when the slide is out, there may be a measure of 2 feet. In the carpenter's rule the inch measure is on one side, continually all the way from 1 to 24, when the rule is unfolded, and subdivided into 8th or half quarters; on this side are also some diagonal scales of equal parts. And upon the edge, the whole length of two feet is divided into 200 equal parts or 100ths of a foot. RºjLES of Court, in Law, are certain orders made from time to time, in the courts of law, which attorneys are bound to ob- serve in order to prevent confusion; and both the plaintiff and defendant are, at their peril also bound to pay obedience to rules made in court relating to the cause depending between them. RUM, a species of vinous spirit, distilled from sugar-canes. RUMEN, in comparative Anatomy, the paunch or first sto- mach of such animals as chew the cud, thence called ruminant animals. RUMI, in the Materia Medica, a name given to mastic of the finer kind. RUMINANT, in Natural History, is applied to an animal that chews over again what it has eaten before: this is popularly called, “chewing the cud.” Ruminatio, in Medicine, and Rw- mination, in Natural Philosophy, are terms of the same family, and of kindred import. RUN, the aftmost part of a ship's bottom, where it grows extremely narrow as the floor approaches the stern-post. Run, is also the distance sailed by a ship. Run, is also used among sailors, for the agreement to work a single passage from one place to another; as, from Jamaica to England, &c. To Run down a Coast, is to sail along by it. To Run down a Wessel, is to pass over her by running against her end-on, so as to sink her. To JRun out the Guns, is, by means of the tackies, to force their muzzles out of the port-holes. . To Run out a Warp, is to carry the end of a hawser out from the ship in a boat, and fasten it to some distant place to remove the ship towards that place, or to keep her steady whilst her anchors are lifted, &c. To let Run a Rope, is to let it quite loose. A Run Man, implies a deserter from a ship of war. RUNDLET, or RUNLET, a small vessel containing an uncer- tain quantity of any liquor, from three to twenty gallons. RUNG PIEADs, a name sometimes given by shipwrights to the upper ends of the floor-timbers, which are otherwise more properly called floor-heads. RUNIC, a term applied to the language and letters of the ancient Goths, Danes, and other northern nations. Many inscriptions in Runic characters are to be found in this country in old churches, and on monumental stones. RUNIc Shafts, were a kind of calendars used in the north of Europe, marked out by lines upon short pieces of boards or smooth sticks, some of which bear the marks of great antiquity. RUNNER, a thick rope used to increase the mechanical power of a tackla. The runner passes through a large block, and has usually a hook attached to one of its ends, and one of the tackle blocks to the other: in applying it, the hook of the runner, as well as the lower block of the tackle, is fixed to the object intended to be removed. RUNNING FIGHT, a battle in which the enemy endeavours to escape, while the victor continues to pursue within gun-shot. RUNNING Rigging, all that part of a ship’s rigging which passes through blocks, &c. and is used in contradistinction to standing rigging. The Running part of a Tackle, is synonymous with the Fall, and is that part on which the power is applied to produce the intended effect. RUPEE, a coin of different parts of the East Indies, of the sterling value of 2s, or a little more or less. RUPERT'S DROPs, a sort of glass-drops with long and slen- der tails, which burst to pieces on the breaking. off of those tails in any part, said to have been invented by Prince Rupert, and therefore called after his name. This surprising phenome- non is supposed to rise from hence, that while the glass is in fusion, or in a melted state, the particles of it are in a state of repulsion; but being dropped into cold water, it so condenses the particles in the external parts of their superficies, that they are easily reduced within the power of each other's attraction, and by that means they form a sort of hard case, which keeps confined the before-mentioned particles in their repulsive state, but when this outer case is broken, by breaking off the tail of the drop, the said confined particles have then a liberty to exert their force, which they do by bursting the body of the drop, and reducing it to a very peculiar form of powder. RUPELLENSIO SAL, Rochelle Salt, a name given to a pecu- liar kind of salt invented by an apothecary of Rochelle, and much esteemed as a valuable medicine. Its composition was, for a long time, kept a profound secret, but it is now well known to most chemists. * RURAL ECONOMY, is a term which comprehends what- ever, tends to the improvement of land for the purposes of grazing or agriculture, either by renovating the soil by manure, the arrangement of crops, or the management of the produce. RUSH. See JUNcus. * .* RUSH, Sumach, a genus of the trigynia order, and in the pent- andria, class of plants, and in the natural method ranking under the 43d order, dumosae. -- RUSMA, a mineral substance, which, mixed with quicklime, takes off the hair. It was well known to the Egyptians and the Greeks. RUSPONQ, a coin of Tuscany value £1.8s. 6d. sterling. TUST, in Corn. See RUBIGo. RUST, in Metal, the partial decomposition of iron and steel : all metallig bodies are liable to rust, even gold is not excepted in some situations. Water is the great agent in producing rust; and when air is assigned as its cause, the aqueous parti. cles it contains is the efficient instrument. Oil, and fat sub- stances, will best preserve metal from corrosion. RUSTIC, that which is unpolished, partaking more of the simplicities of nature than the refinements of art. The term is applied to men, to their employment, their habitations, and the works they perform. RUT, in rural economy, a track or narrow opening formed in a road or field by the wheel of a cart, or other carriage, when the rim is narrow. RUTA BAGA, a plant of the turnip kind, that has lately been introduced into this country from Sweden, and is now cultivated with great success. It opportunely comes into use between the turnip and the grass seasons, on which account its value is considerable. Cattle, sheep, and hogs, eat it with great avidity. RUTA, Rue, a genus of the monogynia order, in the decandria class of plants; and in the natural method ranking under the 26th order, multisiliquae. The calyx is quinquepartite; the petals concave; the receptacle surrounded with ten melliferous pores; the capsule is lobed. In some flowers, a fifth part of the number is excluded. There are seven species. RUTHERFORD, WILLIAM, an English philosopher, was born in 1712, and died in 1771. He is principally distinguished by “A System of Natural Philosophy,” published in 1748. RUTHILA, an ore found in Hungary, Italy, and France. It is generally crystallized. RUTILE, an oxide of titanium. It is of a dark blue red colour, inclining to brown, with a degree of metallic splendour. The longitudinal fracture is foliated, the cross fracture con- choidal and unequal. It is opaque, or slightly translucent, and sometimes sufficiently hard to scratch quartz. RUTULUS, in Roman History, the barrier of the cavea, or place where the wild beasts used in amphitheatrical sports were confined. It was made of iron bars, which turned upon hinges, and flew open when required with great swiftness. RYE, a species of grain much cultivated in some of the northern districts of England. It approaches nearer to wheat than any other grain now in cultivation. There are several varieties. In many places it is used for bread, but unmixed with wheat, it is dry and poor. By gingerbread bakers much rye is consumed, but the distilleries absorb the greater quantity. RYELAND SHEEP, a breed of fine-woolled sheep, originally reared to the greatest perfection in a district of Herefordshire, called the Ryelands, from which the name has been derived. S A C S A F DICTIONARY OF MECHANICAL SCIENCE, S. S, the eighteenth letter of our alphabet: in abbreviations, stands for societas or socius; as R. S. S. for regiae societatis socius, i. e. fellow of the Royal Society. In medicinal prescrip- ...tions, S.A. signifies secundum artem, i. e. according to the rules of art; and in the notes of the ancients, S. stands for sex- tus; SP. for spurius; S.C. for senatus consultum ; S. P. Q. R. for senatus populusque Romanus; S. S. for stratum super stra- tum, i.e. one layer above another alternately ; S.W. B.E. E. Q.V. for, sivales bene est, ego quoque valeo; a form used in Cicero's time, in the beginning of letters. Used as a numeral, S. an- ciently denoted seven ; in the Italian music, S. signifies solo; and in books of navigation, S. stands for south ; S. E. for south- east; S. W. for south-west; S. S. E. for south-south-east, &c. SABAISM, supposed to be the first system of idolatry that ever appeared in the world. It prevailed much in the days of Moses, and is still retained in the East. Sabaism consists of the worship of the stars, or, as the scriptures term it, “the host of heaven.” SABBATARIANS, a sect of Christians, who observe the Jewish or Saturday Sabbath. SABBATH, the seventh day of the week, held sacred among the Jews, to commemorate the completion of creation. The word is pure Hebrew, and signifies cessation or rest. Philo calls it the world's birth-day. . Under the Christian system, it has been transferred to the first day of the week, to commemo- rate the resurrection of Christ. - t SABBATH Day's Journey, about two-thirds of an English mile. SABELLIANS, a Christian sect, who reduced the three per- sons in the Trinity to three states or relations; or rather reduced the whole Trinity to the one person of the Father, making the Word and Holy Spirit to be only emanations or virtues. SABINITES LAPIS, a name given to a stone, in which are preserved the leaves of the common savin. SABLE, in Zöology, the name of a small animal of the weasel kind, the fur of which is highly valued. In Heraldry, Sable is the black colour in the arms of a family. SABRE, a kind of sword, or scimetar, with a very broad and heavy blade, thick at the back, and a little falcated or crooked towards the point. In the use of this weapon the Turks are said to be so exceedingly dexterous, as to cleave a man quite down with a single stroke. Damascus was formerly famous for its manufacture of sabres. SACCHARINE Aci D. See OxALic Acid. SACCHAROMETER, in the Arts, an instrument for ascer- taining the value of worts, and the strength of different kinds of malt liquors. The name signifies a measurer of sweetness. SACCHARUM, SuGAR, or the Sugar Cane, a genus of the digynia order, in the triandria class of plants; and in the matu- ral method ranking under the fourth order, gramina. The calix is two-valved ; the corolla is also bivalved. There are eleven species. See SUGAR. . SACCOLATS, salts formed from the saclactic acid, and but little known. SACERDOTAL, something belonging to the priesthood. SACK OF Wool, a quantity of wool containing just twenty- two stone, and every stone fourteen pounds. In Scotland, a sack is twenty-four stone, each stone containing sixteen pounds. SACK of Cotton Wool, a quantity from one hundred and a half to four hundred weight. - SACKs of Earth, in Fortification, are canvass bags filled with earth. They are used in making entrenchments in haste, to place on parapets, or the head of breaches, &c. or to repair them when beaten down. ' SACKBUT, a musical instrument of the wind kind, being a sort of trumpet, though different from the common trumpet both in form and size: it is ſit to play a bass, and is contrived to be drawn out or shortened according to the tone required, whe- ther grave or acute. - - SACLACTIC ACID, an acid obtained from gum and arabic, and other mucilaginous substances. 93-4. - - SACRAMENT, in general, denotes a sign of something holy or sacred. In the Christian church, baptism and the Lord’s supper claim this term ; and it has been defined in the ritual of the Establishment to mean, an outward and visible sign of an inward and spiritual grace. Few subjects have been made the occasion of more fierce and unholy contentions than this symbol of peace, good will, and brotherly love. SACRE, or SAKER, in Ornithology, a species of falcon, ex- ceedingly strong, bold, and active. Ray says, that it will seize upon the largest birds, and even young goats, for food. SACRIFICE, an offering made to God on an altar. The institution is so ancient as to be deemed nearly coeval with human nature. In some form or other, its adoption seems to be universal. Among Christians, the term is generally restricted to the death of Christ, and the offerings by which that event was typified. §§ILEGE, is church robbery, or a taking of things out of a holy place, as where a person steals any vessels, ornaments, or goods of the church. . SADAR, the Arabian name of the medicinal lotus, described by Dioscorides and many other ancient writers, * SADDLE, is a seat upon a horse's back, contrived for the convenience of the rider. The ancient Romans are supposed not to have made use of saddles and stirrups, and it has been thought that they did not come into use till the time of Constan- time the Great, but this is a great error. SADDLE, a small cleat or block of wood nailed upon the lower yard arms, to retain the studding sail booms in a firm and steady position; for this purpose the cavity on the lower part of the saddle conforms to the cylindrical surface of the yard to which it is attached, and in like manner the hollow on the upper side answers to the figure of the boom, and serves as a chan- nel whereby it may run out or in along the yards, as occasion requires. - SADDle, is also a name given to several circular pieces of wood, as the saddle of a bowsprit, saddle of a boom, &c. SADDLER, one who makes saddles, and furnish necessaries for equestrian equipment. The Saddlers’ Company, in London, was incorporated in 1272. - SADDUCEES, an ancient Jewish sect, who denied the resur- rection, and the existence of angels and spirits. They were the freethinkers of Israel, highly liberal in principles, but dreadfully cruel in practice. SAFETY LAMP. To obviate the destructive effects of car- buretted hydrogen gas, Sir Humphrey Davy turned his atten- tion to the construction of a lamp which would prevent explo- sion; and upon the knowledge of the fact, that flame cannot pass through apertures of small diameter, he constructed what the miners have since, in gratitude, called the Davy. See LAMP. SAFFRON, a well-known plant, much cultivated in Cam- bridgeshire and Essex, and also imported from France, Spain, and Sicily, but that of our own country, when unadulterated, is always preferred. It should be chosen not above a year old, in close, tough, compact cakes, moderately moist, staining the hands when rubbing it, and of the same colour within as on the outside. The cultivation of saffron is attended with much trouble, and requires extraordinary care, and no small degree of patience. - SAFP Ron, Meadow, a poisonous plant, having a bulbous root, somewhat resembling that of a tulip. Under certain modifica- tions, it has been recommended as a remedy for the gout; but we hear of more mischief than advantage resulting from its cultivation. SAFFRON Tree, an East Indian shrub, which grows about two feet high. The flowers, which resemble those of the jessamine, never open but in the night, and seldom continue more than three or four days. They have no smell, but exhibit the colour of saffron, and their cordial virtues are much the same. SAFFRoN, is also a name given to several chemical prepara- tions, from their resemblanee in colour to vegetable saffron. IO X - - 906 S.A., I S A d DICTIONARY OF 'MECHANICAL SCIENCE. SAG APENUM, a medicinal gum resin, whose smell resembles that of a pine. gº © SAGARA, in Hindoo Mythology, is a personification of the OC6an. SAGATHEE, a slight kind of woollen stuff, Serge, or ratteem, sometimes mixed with a little silk. • . . . . . . . . SAGDA, the name of a particular stone of a green colour, having the property of attracting wood.’ SAGE. See SALVIA. . . . . . SAGENE, a Russian long measure, five hundred of which make a verst, equal to seven English feet. SAGGING to Leew ARD, the movement by which a ship makes a considerable lee-way, or is driven far to leeward of the course whereon she apparently sails. It is generally ex- pressed of heavy sailing vessels, as opposed to keeping well to windward, or, in the sea phrase, holding a good wind. SAGITTA, the Arrow, one of the northern constellations. See ConstellATION. * SAGITTA, in Trigonometry, is the same as the versed sine of any arch, and is so called, because it resembles a dart or arrow-standing on the chord of an arc. : - mote the absciss of any curve. SAGITTA, in Geometry, is used by some old authors, to de- f sun enters it about the 7th of December, as is obvious by reference to the Celestial Globe. Boundaries and Contents.-Sagittarius is bounded on the north by Scutum Sobieski and Antinčus; east by Capricornus and Microscopium; south by Corona Australis, Indus, and Telescopium; and west by Scorpio. It contains sixty-nine stars, viz. five of the third magnitude, nine of the fourth, &c. One of the largest stars in this sign, and 6, is situated by the middle of the bow, and rises on the south-east by S. # E. point of the horizon, at London. Its declination is 29° 54'33" south; its right ascension 272° 21'57"; and it rises and culminates as in the following table, for the first day of every month in the year: Meridian altitude 8° 34' 27". “MonTH...] RISES. CULM. MONTH. RiSES. CULM. ho. mi. ho. mi. ho. mi. ho. mi. Jan. 8 30 M. 11 25 M. July 3 32 A. 11 25 A. Feb. 6 18 M. 9 10 M. Aug. 6 40 A. | 9 30 A. Mar. 4 25 M. 7 20, M. Sept. 4 35 A. | 7 30 A. April 2 35 M. 5 25 M. Oct. 2 50 A. 5 40 A. Mlay 12 45 M. 3 35 MI. Nov. 12 54 A. § 3 50 A. June 10 30 A. | 1 20 M. Dec. 10 47 M. . I 45 A. SAGO, a simple brought from the East Indies, of considerable use in diet, as a restorative. It is produced from the pith of a kind of palm which grows in the East Indies, called the cycas circinalis. - - SAGOUIN, in Zöology, the name of a beautiful species of Imonkey. - . - SAGUM, the name of a military garment worn by the Greeks, Romans, and Gauls, in the manner of a cloak or cassock. SAGWIRE, a liquor in the East Indies, drawn from a tree of the palm kind, of the same nature as toddy or palm wine. It is refreshing, wholesome, but inebriating. SAIC, a sort of Grecian ketch, which has no top-gallant sail nor mizzen sail. SAIC, an assemblage of several breadths of canvass, or other texture, sewed together, and extended on or between the masts, to receive the wind, and impel the vessel through the water. The edges of the cloths or pieces of which a sail is composed are generally sewed together with a double seam, and the whole is skirted round at the edges with a cord called the bolt-rope. SAICK, a Turkish vessel rigged in a peculiar manner, and well adapted for the conveyance of merchandise. SAIGA, in Zöology, a species of antelope, the characters of which are, that the borns are pale, and almost transparent, dis- tant at their bases, and bent in form of a lyre. It inhabits Poland, Moldavia, the Carpathian mountains, Caucasus, and may be found on thc borders of the Caspian and Euxine sea. Its resi- stretched out by a tack and sheet. dence is generally in the open desert, in which salt springs abound, and its food is saline, acrid, and aromatic vegetables. SAILS, are all contained either between three or four sides; or, as they are otherwise termed, they are either triangular or qua- drilateral. The former of these are sometimes spread by a yard. as lateen sails, or by a stay, as stay sails, or by a mast, as shoul- der of mutton sails; in all which cases the foremost leech or edge is attached to the yard, mast, or stay, throughout its whole length. The latter, or those which are four-sided, are either extended by yards; as the principal sails of a ship, or by yards and booms, as the studding sails, drivers, ringtails, and all those sails which are set occasionally ; or by gaffs and booms, as the main-sails of sloops and brigantines. The principal sails of a ship are the courses or lower sails; the top sails, which are next in order above the courses, and the top gallant sails, which are extended above the top sails. The courses are, the main-sail, fore-sail, and mizzen; the sprit-sail, main stay-sail, fore stay-sail, and mizzen stay-sail : but more particularly the three first. The main stay-sail is rarely used, except in small vessels. In all the quadrilateral sails, the upper edge is called the head, the sides or skirts are called leeches, and the bottom or lower edge is termed the foot; if the head is parallel to the foot, the two lower corners are denominated clues, and the SAGITTARIUS, the Archer, t , is the last of the autumnal, and the third of the southern signs, agreeably to the fixed zodiac; and the sun accordingly enters it on the 22d of Novem- ber. But reckoning by the visible and moveable zodiac, Sagitta- rius is actually in possession of the first winter sign, for the upper corners earings. In all triangular sails, and in those four-sided sails wherein the head is not parallel to the foot, the foremost corner at the foot is called the tack, and the after lower corner the clue: the foremost head is called the fore leech, and the hindmost the after-leech. The heads of most ‘four-sided sails, and fore-leeches of lateen sails, are attached to their respective yard or gaff by a number of small cords called robands, or by a lacing, and the upper extremities are made fast by earings. The stay-sails, are extended upon stays be- tween the masts, whereon they are drawn up or down occasion- ally, as the curtain slides on its rod, and their lower parts are The main-sail and fore-sail have a rope and a large single block made fast to each clue; the ropes called tacks lead forward to the chess trees and bum- 'kins, and the block receives a thick rope from aft, which is termed the sheet. The clues of the top-sails are drawn out to the extremities of the lower-yards, by two large ropes called top-sail sheets, and the clues of the top-gallant sails are in like manner extended upon the top-sail yard-arms by ropes called top-gallant sheets. The royals are set above the top-gallant sails, and the studding sails beyond the leeches or skirts of the main-sail and fore-sail, and of the top-sails and top-gallant- sails, their upper and lower edges being extended by small yards, and by poles run out beyond the extremities of the yards for this purpose. These sails are, however, only used in mode- rate weather. All sails derive their name from the mast, yard, | or stay, upon which they are extended. Thus the principal sail extended upon the main-mast is called the main-sail; the next above, which stands upon the main-top-mast, is termed the main-top sail; that which is spread across the main-top gallant | mast, is named the main-top-gallant sail; the sail above it is called the main-royal. In the same manner there are the fore- sail, fore-top sail, fore-top-gallant sails, and fore-royal ; the miz- zen, mizzen-top sail, mizzen top-gallant sail, and mizzen royal. Thus also there are the main-stay sail, main top-mast-stay sail, main top-gallant-stay sail, and a middle stay sail, which stands between the two last); all these stay-sails are between the main | and fore mast; the stay sails between the main and mizzen masts are the mizzen stay, sail, the mizzen top-mast stay sail, | the mizzen top-gallant stay sail, and sometimes a mizzen royal- stay sail. The sails between the fore-mast and the bowsprit are the fore stay-sail, the fore top-mast-stay sail, the jib, and sometimes a flying jib ; and even a middle jib : there are be- sides two and sometimes three square sails extended by yards under the bowsprit and jib-booms, one called the sprit-sail, | the second the spirit-sail top-sail, and the third the sprit-sail top-gallant sail ; the studding sails being extended upon the different yards of the main-mast and fore-mast, are also named, according to their stations, the lower top-mast, or top-gallant studding-sails. The ropes by which the lower yards of a ship are hoisted up to their proper height on the masts are called the jears; in all other cases the ropes employed for this purpose are called halliards; hence the sails are expanded by halliards, S A [ S A I 907 DICTIONARY ‘OF MECHANICAL SCIENCE, tacks, sheets, and bow lines; and are drawn up together, or trussed up, by bunt-lines, clue-lines, leech-lines, reef-tackles, slab-lines, and spilling-lines, the higher studding-sails, and the stay-sails are drawn down so as to be taken in by down-hauls, and the courses, top-sails, and top-gallant sails, are wheeled about the mast so as to suit the various directions of the wind. by braces. . * After SAILs, are those that belong to the main mast and mizzen. They keep the ship to windward, on which account ships sailing on a quarter wind require a head-sail and an after sail, one to countermand the other. * . Nettiny SAIL, is only a sail laid over the nettings. . . . SAIL, is also applied to a vessel seen at a distance under sail, as “We saw three sail in the north-east.” To Set SAIL, is to expand the sails in order to begin the action of sailing. To loose. Sails, is to unfurl them, and to let them hang loose to dry. To make Sail, is to extend an addi- tional quantity of sail, so as to increase the ship's velocity. To shorten Sail, is to reduce or take in part of the sails. To strike Sail, is to lower it suddenly, which is particularly used in saluting or doing homage to a superior force, or to one whom the law of nations acknowledges as superior in certain regions. Thus all foreign vessels strike to an English man-of-war in the British seas. See the article SALUTE. SAILING, in Navigation, denotes the act of conducting a vessel from one port to another, by means of the action of the wind upon her sails, being otherwise expressed by the most significant term, Navigation. . SAILING, is distinguished into different cases, 'according to the principles upon which the computations are founded, as Plane Sailing, Middle Latitude Sailing, Mercator Sailing, Glo- bular Sailing, &c. - Plane SAILING, is that which is performed on a supposition of the earth being an extended plane surface, and by means of plane charts, in which case the meridians are considered as parallel lines, the parallels of latitude at right angles to the meridians, and the lengths of the degrees on the meridians, equator, and parallels of latitude, as every where equal. Here the principal terms are the latitude, distance, and departure; difference of latitude and rhumb, longitude having no place in plane sailing. It is obvious, however, that calculations con- ducted on these principles must be too erroneous to be depend- ed upon in any case, and therefore it would be but wasting the reader's time to enter farther into an explanation of this case, which is now nearly if not wholly disused by navigators. Traverse SAILING, may be defined compound plane sailing, being the method of working, or calculating traverse or com- pound courses so as to reduce them into one. This is used when a ship, having to sail from one port to another, is by rea- son of contrary winds, or other obstacles, obliged to tack and sail upon different courses, which are then to be brought into one ; and hence the difference of latitude, departure, and other circumstances, determined as in plane sailing. . Globular SAILING, is the method of estimating a ship's mo- tion and run, upon principles drawn from the globular figure of the earth. In this its most extended sense, globular sailing comprehends Parallel, Mercator, Middle Latitude, and Great Cir- cle Sailing; for a definition of each see the following articles. Parallel SAILING, is the sailing on a parallel of latitude, or parallel to the equator, of which there are three cases. 1. Given the distance and difference of longitude; to find the latitude, which is performed by the following rule:–As the dif- ference of long.: the distance : : the radius: the cosine of the latitude. - 2. Given the latitude and difference of longitude ; to find the distance. Rule. As radius : the cosine of the latitude : : the difference of longitude : the distance. - 3. The latitude and distance being given to find the difference of longitude. Rule : As cosine of latitude : radius :: the dis- tance : the difference of longitude. Middle Latitude SAILING, is a method of resolving the cases of globular sailing, by means of the middle latitude between that departed from and that come to. This method is not accurate, being founded on the principles of plane and globular sailing conjointly ; viz. on a supposition that the departure is reckoned as a meridional distance in that latitude, which is the middle parallel between the latitude, sailed from and the latitude come to : which would be correct, if the cosine of a middle latitude was an arithmetical mean between the cosines of two extreme latitudes; and the departure between two places on an oblique rhumb, equal to the meridional distance in the middle latitude; but neither of these cases obtain. Yet when the parallels are near the equator, or near to each other, in any latitude, the error is not considerable, This method seems to have been invented on account of the easy manner in which the several cases may be resolved by the traverse table; and when a table of meridio- nal parts is not at hand, the computations may be made as foll- lows; viz. Take half the sum of the two given latitudes for the middle latitude, then say, - 1. As cosine of mid. lat. : the radius :: the departure: diff. of longitude. 2. As cosine of mid. lat. : tan. of course : ; diff. of lat. : diff. of longitude. w - Right SAILING, is when a voyage is performed on some one of the four cardinal points. If a ship sail under the meridian on the north or south points, she varies not in longitude. If she sail under the equinoctial on the east or west points, she changes only the longitude. If from any place she sails directly east or west, she only alters the longitude. Oblique SAILING, though in many cases the bearing and dis- tances of places are determined by the solution of right-angled triangles, yet at sea there are several in which oblique posi- tions can be observed. The doctrine of plane triangles is also applicable to the method of sailing by windward. It may be ob- served, in general, that when the wind is directly or partly against the ship’s direct course to the place whither she is bound, she reaches her port by a kind of zigzag or z-like course, which is made by sailing with the wind first on one side of the ship and then on the other. The windward or weather-side of a ship is that side on which the wind blows; the other being called the leeward or lee side. When a ship sails the same way the wind blows, and the wind is said to be right aft, or right astern, her course is then sixteen points from the wind. When a ship sails with the wind blowing directly across her, she is said to have the wind on the beam, and her course is eight points from the wind. When a ship endeavours to sail towards that point of the compass from whence the wind blows, she is said to sail on the wind, or to ply to windward. A vessel sailing as near as she can to the point from whence the wind blows, is said to be close hauled: most ships will lie within about six points of the wind, but sloops and some other vessels will lie much nearer. When a ship sails on a wind, the windward tacks are always hauled forwards and the leeward sheets aft. The starboard tacks are aboard when the starboard side is to windward, and the lar- board to leeward ; the larboard tacks are aboard when the lar- board side is to windward, and the starboard to leeward. In order to know how near the wind a ship will lie, observe the eourse she goes on each tack, when she is close-hauled ; then half the number of points between the two courses will shew how near the wind that ship will lie. The most common cases in turning to windward may be constructed by the following precepts. Having drawn the meridian and parallel of latitude (or east and west line) in a circle representing the horizon of the place, mark in the circumference of the place of the wind; draw the rhumb passing through the place bound to, and lay thereon the distance of that place from the centre. On each side of the wind, lay off in the circumference the points of de- grees, shewing how near the wind the ship can lie, and draw these rhumbs; the first course will be on one of these rhumbs, according to the tack the ship leads with ; draw a line from the place bound to, parallel to the other rhumb, and meeting the first, and this will shew the course and distance on the other tack. Mercator's SAILING, is the art or resolving the several cases of globular sailing by plane trigonometry, with the assistance of a table of meridional parts, or of logarithmic tangents. Me- ridional parts, miles, or minutes, are the parts by which the me- ridians in a Mercator's Chart increase, as the parallels of lati- tude decrease. The cosine of the latitude of any place being equal to the radius or semi-diameter of that parallel; therefore, in the true sea-chart, or nautical planisphere, this radius being the radius of the equinoctial, or whole sine of ninety degrees, 908 S A L S A I DICTIONARY OF MECHANICAL SCIENCE, the meridional parts at each degree of latitude must increase as the secants of the arch contained between that latitude and the equinoctial decrease, . The manner of working with the me- ridional parts, and logarithmic tangents, will appear from the two following cases. . 1. Let the latitudes of two places be given, and the meridi- onal difference of latitude between them be required. By the meridional parts, when they are on the same side of the equa- tor, say the dtfference ; when on different sides, the sum of the meridional parts answering to each latitude will give the me- ridional difference of latitude required. By logarithmic tan- gents, when they are on the same side of the equator, say the difference of the logarithmic tangents; when on different sides, the sum of the logarithmic co-tangents, abating the index of the half co-latitudes, divided by 12,63, will give the meridional dif- ference of longitude required. - . 2. Let the latitude of one place and the meridional difference of latitude between that and another place be given, and the latitude of the other place be required. The sum of the meri- dional parts of the given latitude, and the given meridional dif- ference of latitude, when they have like names, found in the table of meridional parts, will give the latitude sought. Or, mul- tiply the given meridional differences of latitude by 12,68, and in the former case subtract, but in the latter case add the pro- duct to the logarithmic tangent of the given half co-latitude, the degrees corresponding to the tangent of the remainder, or of the sum, being doubled, will give the co-latitude required. Circular, or Great Circle SAILING, is the art of finding what splaces a ship must go through, and what courses to steer, so that her track shall be in the arc of a great circle, or nearly so, passing through the place sailed from, and that bound to. This method of sailing has been proposed, because the shortest dis- tance between two places on the sphere is an arc of a great circle intercepted between them, and not the spiral or rhumb passing through them, unless that rhumb coincides with a great circle which can only be on a meridian or on the equator. As the solutions of the cases in Mercator’s sailing are performed by plane triangles, in this method of sailing they are resolved by the means of spheric triangles. To bring sailing to certain rules, M. Renau computes the force of the water against the ship's rudder, stern, and side, and that of the wind against her sails. . In order to this, he, 1. considers all fluid bodies, as the air, water, &c. as composed of little particles, which when they act upon or move against any surface, do all move parallel to one another, or strike against the surface after the same man- mer. 2. That the motion of any body, with regard to the surface on which it is to strike, must be either perpendicular, parallel, or oblique. The author then proceeds to illustrate his observa- tions with several examples.—Another author on this subject observes, when a ship changes her state of rest into that of motion, as in advancing out of a harbour, or from her station at anchor, she acquires her motion very gradually, as a body which arrives not at a certain velocity till after an infinite repetition of the action of its weight. The first impression of the wind greatly affects the velocity, because the resistance of the water might destroy it, since the velocity being but small at first, the resistance of the water which depends upon it will be very feeble, but as the ship increases her motion the force of the wind on her sails will be diminished ; whereas, on the contrary, the resistance of the water on the bow will accumulate in pro- portion to the velocity with which the vessel advances. Thus the repetition of the degrees of force which the action of the sails adds to the motion of the ship, is perpetually decreasing, while, on the contrary, the new degrees added to the effort of resistance on the bow, are always augmenting. The velocity is then accelerated in proportion as the quantity added is greater than that which is subtracted : but when the two powers be- come equal, when the impression of the wind upon the sails has lost so much of its force as only to act in proportion to the opposite impulse of resistance on the bow, the ship will then acquire no additional velocity, but continue to sail with a con- stant uniform motion. The great weight of the ship may indeed prevent her from acquiring her greatest velocity, but when she has attained it, she will advance by her own intrinsic motion, without gaining any new degree of velocity, or lessening what she has acquired. She moves then by her own proper force, in vacuo, without being afterwards subject either to the effort of the wind on the sails, or to the resistance of the water on the bow. If at any time the impulsion of the water on the bow should destroy any part of the velocity, the effort of the wind on the sails will revive it, so that the motion will continue the same. It must, however, be observed, that this state will only subsist when these two powers act upon each other in direct opposition, otherwise they will mutually destroy one another. The whole theory of working ships depends on this counter- action, and the perfect equality which should subsist between the effort of the wind and the impulsion of the water. Order of SAILING, the general disposition of a fleet of ships when proceeding on a voyage or an expedition. It is generally found most convenient for ships of war to be formed in three parallel lines or columns. • , * - SAIL-LOFT, a large apartment in dock-yards, where the sails are cut out and made. SAILMAKER, a subaltern officer on board ships of war, who, with his mates, has the care of repairing or altering the sails, according to the captain's directions. g SAILOR, a person trained in the exercise of fixing the ma- chinery of a ship, and managing her either at sea, or in a road or harbour. SAINTFOIN, in Agriculture, a species of plant, of the artifi- cial grass kind, frequently raised as food for cattle, both green and dried : it is sometimes called holy-hay, or wholesome hay, from its peculiar nutritive qualities. It rises in the stem from one to two feet high, and has tufts of red flowers from three to five inches in length. It was originally brought into this king- dom from France, or the Low Countries. * SAKER, a name formerly used for a small species of cannon, of which there were three sorts. - - SAI, AMMONIAC, in Chemistry, a salt composed of muria- tic acid and ammonia, or the volatile alkali. This substance, highly refined, is called spirits of hartshorn. SAL AMMONIAC, in the Materia Medica, is an inodorous salt, of a bitterish, acid, and cool taste; persistent in the air, and not easily reduced to powder. SALACASE, the name given to a bird in the Philippine islands, by whose flight the inhabitants pretend to foretell future events. SALAD HERBs, in Gardening, esculent plants, from which salads are collected. These are of various kinds, and are now procured at all seasons of the year. SALAGRAMA, a stone found in the river Nepaul, and con- sidered by many sects of Hindoos as sacred, and containing something mystical. SALAMANDER, a name given to several species of lizards. Of this creature many strangely fabulous accounts have been published. SALARY, a stipend allowed to any person, in consideration of his industry and services, in another man’s business. SALAYASIR, a small species of duck, not larger than a pigeon, inhabiting the marshes of the Philippine islands. It is most beautifully coloured. SALE of Goods. If a man agrees for the purchase of goods, he shall pay for them before he carries them away, unless some term of credit is expressly agreed upon by the parties. If a man, upon the sale of goods, warrants them to be good, the law annexes to this contract a tacit warranty, that if they be not so, he shall make compensation to the purchaser: such warranty, however, must be on the sale. But if the vender knew the goods to be unsound, and has used any art to disguise them, or if in any respect they differ from what he represents them to be to the purchaser, he will be answerable for their goodness, though no general warranty will extend to those de- fects that are obvious to the senses. If two persons come to a warehouse, and one buys, and the other, to procure him credit, promises the seller, “If he do not pay you, I will ; ” this is a collateral undertaking, and void without writing, by the statutes of frauds; but if he say, “Let him have the goods, I will be your paymaster,” this is an absolute undertaking as for himself, and he shall be intended to be the real buyer, and the other to act only as his servant. The question in these cases is always which party was originally trusted. For if the party to whom the goods are delivered was ever considered responsible, the en- S A L S A L 909 DICTIONARY OF MECHANICAL SCIENCE, gagement of the other is void, unless it is in writing; after earnest is given, the vender cannot sell the goods to another without a default in the vender, and therefore, if the vendee does not come and pay, and take the goods, the vender ought to give him notice for that purpose: then if he does not come and pay, and take away the goods in convenient time, the agreement is dissolved, and he is at liberty to sell them to any other person. SALEP, or SA Lop. See SAGo. - SALET, in War, a light covering for the head, anciently worn by the light horse. It was little more than a bare cap, but would resist a heavy blow. SALIANT, in Fortification, projecting; as, a saliant angle. SALIC, or SALIQUE LAW, lea, calica, an ancient and funda- | mental law of the kingdom of France, usually supposed to have been made by Pharamond, or at least by Clovis, in virtue of which males only are to inherit. The ancient Romans allowed no sovereign women. SALIVA. The fluid secreted in the mouth, which flows plenti- fully during a repast, is known by the name of saliva. SALIVATION, in Medicine, a promoting of the flux of saliva by means of medicines, chiefly by mercury. SALIX, the Willow, a genus of the diandria class of plants, and in the natural method ranking under the 50th order amen- taceae. There are 53 species. SALLYPORT, a large port on each quarter of a fireship, out of which the officers and crew make their escape into the boats as soon as the train is fired. - SALMO, the Salmon, in Natural History, a genus of fishes of the order abdominales. Gmelin enumerates fifty-five species, and Shaw sixty-two, of which we shall notice the following: The common salmon. This abounds principally in the northern seas, which it quits at particular pcriods, to ascend rivers to a very considerable height, and deposit its spawn in them. In order to gain the favourite spots in rivers for this purpose, which are sometimes at the distance of several hundred miles from the ocean, these fishes will overcome difficulties of surprising extent, stemming the most rushing currents, and leaping with astonishing activity over various elevations. It is related that the same individual fishes will return to the same spot for a suc- cession of seasons ; in this respect exhibiting preferences simi- lar to those of birds in similar circumstances.—The common trout is found in almost all the European streams, at least such as are cool and clear.—The red char is about a foot long, very similar in form to the common salmon, but more slender. It abounds in the rivers of Siberia, and the lakes of Germany; and in this country, in the lakes of Cumberland and Westmoreland. It is considered as one of the highest delicacies, and has the most brilliant colours and finest flavour, when inhabiting the coldest waters.-The smelt is about seven inches long, highly elegant, of a tapering form, and semi-transparent appearance. ——The Greenland salmon. These abound off the coast of Green- land, where they are taken in vast quantities and dried, not only for the use of man but of cattle, for which they constitute a va- luable food in winter. It is about the size of a smelt.—The grayling is about a foot and a half long, and abounds in the mountainous rivers in Europe and Asia. It resembles the trout in form. In some of the rivers of England, it is found in great perfection. SALON, or SALóo N, in Architecture, a very lofty spacious hall, vaulted at top, and sometimes comprehending two stories or ranges of windows. - SALSOLA, saltwort, kali, &c. a genus of the class and order pentandria digynia, and in the natural method ranking under the 12th order, holoraceae. The species are thirty-one. This plani when burnt produces barilla. - SALT, CoMMON. The preparation of that kind of salt which is used for culinary and economical purposes (muriate of soda) depends upon the well-known fact, that the salt contained in the sea water or brine springs, being a fixed body, will not rise with the vapour of the water. All therefore that is wanted is to expose any water containing salt to evaporation. SALT Marsh, such pasture, lands as lie near the sea, and are sometimes overflowed with the tides. SALTPETRE. See NITRE, SALTPITS, reservoirs on a coast, to contain sea-water for 93-4. the purposes of making salt. The saltness of the sea, lakes, &c. is a thing that has long puzzled and perplexed philosophers to account for. The honourable Mr. Boyle believes it to be supplied not only from rocks and masses of salt, which at the beginning were, or in some countries may yet be found, either at the bottom of the sea, or at the sides, where the water can reach them, but also from the salt which the rivers, rains, and other waters, dissolve in their passage through divers parts of the earth, and at length carry with them into the sea. Buffon, and most modern philosophers, acquiesce in this opinion. SALTS, in Chemistry, are all the crystallizable acids, or alkalies, or earths, or combination of acids with alkalies, earths, or metallic oxides. - SALUTATION, the act or ceremony of saluting, greeting, or paying respect or reverence to any one. In their modes of salutation, most nations have something peculiar. SALUTE, a testimony of respect or of homage rendered by the ships of one nation to those of another, or by ships of the same nation to a superior or an equal. This ceremony is va- riously performed, according to the circumstances, rank, or situation of the parties: . it consists in firing a certain number of cannon or volleys of small arms, in striking the colours or topsails, or in three general shouts of the whole ship’s crew mounted upon the yards and rigging for that purpose. SALUte, the principal regulations with regard to salutes in the royal navy are as follow :—When a flag-officer salutes the admiral and commander-in-chief of the fleet, he is to give him fifteen guns; but when captains salute bim, they are to give him seventeen guns; the admiral or commander-in-chief of the fleet, is to return two guns less to flag-officers, and four less to baptains. Flag-officers saluting their superior or senior officer, are to give him thirteen guns. Flag-officers are to return an equal number of guns to flag-officers bearing their flags on the same mast, and two guns less to the rest, as also to captains. When a captain salutes an admiral of the white or blue, he is to give him fifteen guns; but to vice and rear admirals, thirteen guns. When a flag-officer is saluted by two or more of his majesty’s ships, he is not to return the salute till all have finished, and then to do it with such a reasonable number of guns as he shall judge proper. In case of the meeting of two squadrons, the two chiefs only are to exchange salutes. And if single ships meet a squadron consisting of more than one flag, the principal flag only is to be saluted. No salutes shall be repeated by the same ships, unless there has been a separation of six months at least. None of his majesty’s ships of war, commanded only by captains, shall give or receive salutes from one another in whatsoever part of the world they meet. A flag- officer, commanding in chief, shall be saluted upon his first hoisting his flag, by all the ships present, with such a number of guns as is allowed by the first, third, or fifth articles. When any of his majesty’s ships shall meet with any ship or ships belonging to any foreign prince or state, within his majesty's seas, (which extend to Cape Finisterre,) it is expected that the said foreign ships do strike their topsail, and take in their flag, in acknowledgment of his majesty’s sovereignty in those seas: and if any shall refuse, or offer to resist, it is enjoined to all , flag-officers and commanders, to use their utmost endeavours to compel them thereto, and not suffer any dishonour to be done to his majesty. And if any of his majesty’s subjects shall so much forget their duty, as to omit striking their topsail in pass- ing by his majesty’s ships, the name of the ship and master, and from whence, and whither bound, together with affidavits of the facts, are to be sent up to the secretary of the admiralty, in order to their being proceeded against in the admiralty court. And it is to be observed, that in his majesty’s seas, his majesty’s ships are in no ways to strike to any; and that in no other parts, no ship of his majesty is to strike her flag or topsail to any foreigner, unless such foreign ship shall have first struck, or at the same time strike her flag or topsail, to his majesty's ship. : The flag-officers and commanders of his majesty’s ships are to be careful to maintain his majesty’s honour, upon all occasions, giving protection to his subjects, and endeavouring, what in them lies, to secure and encourage them in their lawful com- merce; and they are not to injure, in any manner, the subjects of his majesty’s friends and allies. If a foreign admiral meets with any of his majesty’s ships and salutes them, he shall re- 10 Y 930 S A M S A N Dic rion ARY OF MECHANICAL SCIENCE. ceive gun for gun. If he be a vice-admiral, the admiral shall answer with two guns less. If a rear-admiral, the admiral and vice-admiral shall return two less; but if the ship be com- manded by a captain only, the flag-officers shall give two guns less, and captains an equal number. When any of his majesty's ships come to an anchor in a foreign port or road, within can- non-shot of its forts, the captain may salute the place with such a number of guns as have been customary, upon good assurance of having the like number returned, but not otherwise. But if the ship bears a flag, the flag-officer shall first carefully inform himself how flags of like rank belonging to other crowned heads have given or returned salutes, and to insist upon the same terms of respect. It is allowed to the commanders of his majesty's ships in foreign parts, to salute the persons of any admirals, commanders-in-chief, or captains of ships of war of foreign nations, of foreign noblemen, or strangers of quality; as also the factories of the king's subjects, coming on board to visit the ship; and the number of guns is left to the commander, as shall be suitable to the occasion and the quality of the per- sons visiting; but he is nevertheless to remain accountable for any excess in the abuse of this liberty. If the ship visited be in company with other ships of war, the captain is not to make use of the civilities allowed in the preceding articles, but with leave and consent of the commander-in-chief, or the senior captain. Merchant-ships, whether foreigners or belonging to his majesty’s subjects, saluting the admiral of the fleet, shall be answered by six guns less; when they salute any other flag-ships, they shall be answered by four guns less; and if they salute men-of-war commanded by captains, they shall be answered by two guns less. If several merchant-ships salute in company, no return is to be made till all have finished, and then by such a number of guns as shall be thought proper; but though the merchant- ships should answer, there shall be no second return. None of his majesty's ships of war shall salute, any of his majesty's forts or castles in Great Britain or Ireland, on any pretence whatsoever. SALWAGE, a third part of the value of any thing reco- vered from the enemy, after having remained in his possession twenty-four hours, or of any thing dragged up from the bottom of the sea. - Salvage-Money, is a reward allowed by the civil and statute law, for the saving of ships or goods from the danger of the sea, pirates, or enemies. When any ship is in danger of being stranded or driven on shore, justices of the peace are to com- mand the constables to assemble as many persons as are necessary to preserve it; and, on its being preserved by their means, the persons assisting therein shall, in thirty days after, be paid a reasonable reward for the salvage, otherwise the ship or goods shall remain in the custody of the officers of the cus- toms as a security for the same. SALVER, a flat dish, commonly of silver or other precious metai, used to set glasses on to serve wine and other liquors. SALVIA, SAGE, a genus of the monogynia order, in the dygi- nia class of plants, and in the natural method ranking under the 42d order, verticillatae. There are 79 species. SALVING Sheep, in rural economy, the dressing of them with tar and grease, against the scab and other diseases. SAMARITANS, an ancient sect among the Jews, still sub- sisting in some parts of the Levant, under the same name. SAMARRA, a garment worn by heretics condemned by the Inquisition to be burned. It is a kind of frock made of sack- cloth, of a saffron colour, and painted with flames pointing downwards. Sometimes the unhappy victim's picture is drawn on it, with devils dragging him to perdition. SAMBUCUS, Elder, a genus of the trigynia order, in the pentandria class of plants, and in the natural method ranking under the 43d order, dumosae. The species are only five. SAMIA TERRA, in "the Materia Medica, an earth of the marl kind, found in the island of Samos, and much used both in medicine, and in the pottery of the ancients. SAMIEL, the Arabian name of a hot wind peculiar to the desert of Arabia. SAMP, a name given in some parts of America to a sort of bread, made of maize or Indian corn. It has been said, that those who feed on this sort of bread are never subject to the stone, and that they also escape many other disorders. SAMPHIRE, a Sea Weed, found on land in the vicinity of the sea shore, and which is troublesome, and difficult to extirpate. - * SAMPHIRe, for pickling, is a herb generally found growing on cliffs near the sea. The vicinity of Dover is supposed to produce some of the best. - SAMPLE, of grain, seed, merchandise, &c is a small portion of any such articles as are to be sold, taken to market, or other places, for inspection, and as a specimen of the quality of the whole. The sample should never be superior to the aggregate which it represents. * - - SAMSON'S POST, a sort of pillar erected in a ship’s hold, between the lower deck and the keelson, under the edge of a hatchway, and furnished with several notches, which serve as steps to ascend or descend. This post, being firmly driven into its place, not only serves to support the beam and fortify the vessel in that place, but also to prevent the cargo, or materials contained in the hold, from shifting to the opposite side, by the rolling of the ship in a turbulent and heavy sea. SAMson’s Post, is also the name of a strong piece of timber used on board ships of war, which being placed in a sloping position, with the upper end resting against a beam, serves, by means of a single block lashed near its middle, to form a return for a tackle-fall, and therefore affords space for a greater num- ber of hands to clap on. - SANATADOS, a name given by the natives of Sicily to the spongy excrescence found on the stalk of the dog-rose. This, dried, and reduced to a powder, they use as an antidote against the effects of venomous bites. When a viper has inflicted a wound, the place having been scarified, is sprinkled over with this powder, and large doses are taken internally in strong wine. Softened into a poultice with oil, it is said to be efficacious in the bite of a mad dog; the powder, mixed with broth or weak fluids, being at the same time 1aken internally. In favour of this specific, the opinion is very old. Pliny says. that the root of the wild rose, from the stalk of which this sub- stance grows, was revealed in a dream, for the curing of this dreadful malady. The application is at least worth trying, the substance being very common, and to be procured without expense or difficulty. - SANCTUARY, among the Jews, was the holiest and most retired place in the temple, in which was preserved the ark of the covenant, and into which no one was permitted to enter, except the high priest, and he only once a year. SANctUARY, in our ancient customs, denotes an asylum or place, privileged by the prince, for the security of persons guilty of capital offences. SAND, in Natural PHistory, a genus of fossils, of great use in the glass manufacture: the white writing sand being em- ployed for making the white glass, and a coarse greenish look- 1ng sand for the green glass. In agriculture it seems to be the office of sand to make unctuous earths fertile, and fit to support vegetables, &c. See HUs BANDRY. - SAND Bags, in the art of War, are bags filled with earth or sand, holding each about a cubic foot; their use is to raise pa- rapets in haste, or to repair what is beaten down. SAND Flood, a terrible mischief incident to the lands of Suf- folk, and some other parts of England; which are frequently covered with vast quantities of sand, rolling in upon them like a deluge of water from sandy hills in their neighbourhood. The flowing of sand, though far from being so tremendous and hurtful as in Arabia, is of very bad consequences in this country, as many valuable pieces of sand has thus been entirely lost. The best mode of stopping these ravages is to plant the arundo arenaria, and other plants which take firm root in the sand. - SANDAL, a rich kind of slipper, made of gold, silk, or other precious stuff, and worn chiefly by the Greek and Roman ladies. It consisted of a sole, having an opening at one extremity to embrace the ancle, but leaving the upper part of the foot bare. Sandals are still worn in many countries, under many variations. SANDAL Wood, a beautifully coloured wood, hard, and fra- grant in smell. It grows chiefly in India, and is valued for its medicinal virtues, and for inlaying in cabinet work. SANDARACH, in Natural History, a very beautiful native fossil. S A P. S A T DICTIONARY OF MECHANICAL SCIENCE. 911. SANDARAch Gum, a resinous juice, which exudes from the trunks and thick branches of several kinds of juniper, in warm climates, and particularly on the coast of Africa, from incisions made in the bark. It has a light agreeable smell, and is sometimes used medicinally, but [more generally in making varnishes. - - SANDERLING, a small sprightly bird, found chiefly on the sea coasts. They are numerous on the shores of Cornwall. SANDIVER, a whitish salt, continually cast up from the metal, as it is called, whereof glass is made ; and swimming on its surface, is skimmed off. SANDSTONE, in Mineralogy, is essentially composed of grains or particles of sand, either united by a mixture with other mineral substances, or adhering without any visible cement. The grains of sandstones are generally quartz, sometimes inter- mixed with felspar or slate, - SANGUIFICATION, in Physiology, the conversion into blood of the materials which supply the losses experienced by that fluid in nutrition, growth, secretion, and the other vital processes to which it is subservient. - SANGUINARIA, in Botany, a name suggested by the blood- coloured juice of the plant. Others, however, have derived the name from its efficacy in stopping hemorrhages. SANGUINE, warm, bold, brisk, daring, abounding in blood. SANGUINe Stone, a kind of jasper, brought from New Spain, of a dark brown colour, marked with spots of a blood-red. It is sometimes called blood-stone from its supposed virtue to stanch blood, either when applied to the affected part, having been first dipped in water, or by the patient grasping it in his hand. SANHEDRIM, among the ancient Jews, the supreme coun- cil court, or court of judicature, in which were despatched all great affairs both of religion and civil policy. SANIDIUM, in Natural History, a genus of fossils in the class of the selenitae. SANIES, in Medicine, a serous putrid matter, issuing from wounds; it differs from pus, which is thicker and white. SANQUA, in Botany, a shrub nearly resembling tea, and found in Japan. Its leaves, when dried, yield a fragrant smell. The Japanese females use the decoction for washing their hair. Thunberg says, the leaves are sometimes mixed with tea, to increase its odour. SANTEO, in Botany, a name given by the people of Guinea to an herb, which being boiled in water, communicates a virtue to the fluid, that cures diseases in the eyes when washed with it. SAP. The sap of plants, in general, is very compound in its nature ; and contains most saccharine, mucilaginous, and albu- minous matter in the alburum ; and most tannin and extract in the bark. The cambium, which is the mucilaginous "fluid found in trees between the wood and the bark, and which is essential to the formation of new parts, seems to be derived from these two kinds of sap ; and probably is a combination of the muci- laginous and albuminous matter of one with the astringent mat- ter of the other, in a state fitted to become organized by the separation of its watery parts. SAP, or SAPP, in the art of War, is the digging deep under the earth of the glacis, in order to open a covered passage into the moat. - SA P-Colours, a name given to various expressed juices of a viscid mature, which are inspissated by slow evaporation for the use of painters; as sapgreen, gamboge, &c. SAPANARIA, a name given to several plants, because the leaves being bruised yields a substance producing a lather like Soap. SAPPHIRE. Telesia of Hany and corundum of Bournon. A valuable mineral of a beautiful blue or red colour, sometimes white, green, and yellow. After the diamond it is the hardest substance in nature. The constituents of the blue sapphire, according to Klaproth, are 92.5 alumina, 6'5 lime, and oxide of I TOR1. SAPINDUS. or INDIAN So AP, the acrid rind of the fruit serving instead of soap, but not without hazard of injuring the texture of the cloth. SAPONACEA TERRA, is a kind of native alkali, of the nitre found on the surface of the earth, mixed with dirt, &c. in the vicinity of Smyrna; and hence sometimes called Smyrna earth. It boils up apparently out of the ground, and presents itself as a fine whitish salt. . With other ingredients it is made into soap, and applied to other purposes. SARABANDE, a dance said to be originally derived from the Saracens. The tune of the sarabande is both expressive and majestic. - - SARCASM, in Rhetoric, a keen bitter expression, which has the true point of satire, by which the orator scoffs and insults his enemy; such was that of the Jews to our Saviour, “He saved others, himself he cannot save.” - SARCOCOLL, a vegetable substance intermediate between Sugar and gum, partaking in some measure of the properties of each, but certainly approaching nearer to sugar than to gum. SARCOPHAGUS, a sort of stone coffin or grave, in which the ancients interred those whom they did not burn. The stone of which these receptacles were originally made, resembled a reddish pumice-stone. It had a saltish taste, and was reported to decompose every portion of the body, excepting the teeth, in about forty days. SARDACHATES, a species of agate, frequently found on the margins of rivers in the East Indies. SARDIAN, a precious stone, of a blood colour, semitrans- parent, and sometimes called carnelian. - SARDOA, a poisonous plant, which grows plentifully in Sardinia, sometimes called water crowfoot. SARDONYX, a precious stone consisting of a mixture of the chalcedony and carnelian, sometimes in strata, but at other times blended together. SARISSA, a long spear used by the Macedonians. SARON, in Greek Mythology, the particular god that pre- sided over sailors. - SAROS, a period of 223 lunar months. SARPLAR OF Wool, a quantity of wool, called sometimes a pocket, or half sack. A sack contains eighty tods, a tod two stones, and a stone fourteen pounds. SARRASIN, in Fortification, a kind of portcullis, otherwise called a herse, hung with ropes over the gates of a town or fortress, and let fall in case of a surprise. - SARSAPARILLA, in Pharmacy, the root of the rough smilax of Peru, consisting of a great number of long strings hanging from one head; these long roots, the only parts made use of, are about the thickness of a goose quill, or thicker, flexible, and composed of fibres running their whole length; they have a bitterish, but not ungrateful taste, and no smell; and as to their medicinal virtues, they are sudorific and attenuant, and should be given in decoction, or by way of diet-drink. SASHES, in Military language, are badges of distinction worn by officers, either over the shoulders or round the waist. They are made of crimson silk. SASSAFRAS, in Pharmacy, the wood of an American tree of the laurel kind, imported in large straight blocks; it is said to be warm, aperient, and corroborant; and is frequently employ- ed, with good success, for purifying the blood, for which purpose an infusion, in the way of tea, is a very pleasant drink; its oil is very fragrant, and possesses most of the virtues of the wood. SASSOLIN, in Mineralogy, concrete native boracic acid, so called from being found on the banks of a hot spring at Sasso, in Italy. SATELLITIAN MACHINE, a machine by which the motions of the satellites, or secondary planets, are produced by wheel work, in the same way that the motions of the primaries are effected by a planetarium. Several such machines have been invented. - SATELLITE, a secondary planet moving round another planet, as the moon round the earth. SATIN SPAR, fibrous limestone. SATIN, a kind of silken stuff, very smooth and shining. The woof is coarse, and hidden underneath the warp, which is fine, and stands out, and on this depends its gloss and beauty, which give its value and price. The finest satins are said to be at Florence and Genoa. Chinese satins, richly embroidered, were once in high estimation, but our own manufactures are at pre- sent equal in most respects to the foreign. The colours and ſlowers are various, and the price is regulated accordingly. SATIRE, any discourse in which a person is reprehended ; but more particularly a poem in which the follies and vices of persons are wittily exposed in order to their reformation. 912 is A w. S A W DICTIONARY OF MECHANIGAL science. SATISFACTION, in Law, a recompense made for an injury done, or the payment of money due on bond, judgment, or bill. SATRAPA, or SATRApes, in Persian Antiquity denotes an admiral, but more commonly the governor of a province. . . SATURATION. Some substances unite in all proportions. Such, for example, as acids in general, and some other salts with water; and many of the metals with each other. But there are likewise many substances which cannot be dissolved in a fluid, at a settled temperature, in any quantity beyond a certain proportion. Thus water will dissolve only about one-third of its weight of common salt, and, if more be added, it will remain solid. A fluid which holds in solution as much of any substance as it can dissolve, is said to be saturated with it. But satu- ration with one substance does not deprive the fluid of its power of acting on and dissolving some other bodies, and in many cases it increases this power. For example, water satu- rated with salt will dissolve sugar; and water saturated with carbonic acid will dissolve iron, though without this addition its action on this metal is scarcely perceptible. The word saturation is likewise used in another sense by chemists: the union of two principles produces a body, the properties of which differ from those of its component parts, but resemble those of the predominating principle. When the principles are in such proportion that neither predominates, they are said to be satu- rated with each other; but if otherwise, the more predominant principle is said to be sub-saturated or under-saturated, and the other super-saturated or over-saturated. - SATURN. See AstroNoMY. SATURNALIA, feasts celebrated among the Romans, in honour of Saturn, in which riot and debauchery prevailed among all ranks. M. Dacier observes, that the Saturnalia were not merely to honour Saturn, but to keep in remembrance the golden age, when all mankind were on a level. SATYR, in Mythology, a fabulous kind of demigod, who, with the fawns and sylvans, presided over groves and forests, under the direction of Pan. SAUCER of A CAPst AN, is a socket of iron let into a wooden stock or standard, called the step, resting upon and bolted to the beams. Its use is to receive the spindle or foot on which the capstan rests and turns round. ... tº SAUCISSE, in the Military art, is a long train of powder sewed up in a roll of pitched cloth or leather, serving to set fire to mines. To every mine there are generally two, that if one fail, the other may take effect. Their length is determined by circumstan;ces. . . - - SAUcisson, in Fortification, a kind of faggot made of thick branches of trees, bound together, to cover the men while ex- posed to the enemy’s fire, when on some hazardous employment. It is also used to repair breaches, stop passages, and make traverses over wet ditches, SAVINE. See JUNIPER. SAVIOUR, Order St. a religious order in the Romish church, founded by St. Bridget, about the year 1345; and so called from its being pretended that our Saviour himself dictated to tha foundress: its constitutions and rules. SAVORY, in Botany, a plant, of which the leaves are warm aromatic, of a grateful smell, and pungent to the taste. There are two kinds, the winter and summer savory. SAW, an instrument which serves to cut into pieces several solid matters; as wood, stone, ivory, &c. SAW MILLS, constructed for the purpose of sawing either timber or stone, are moved by animals, by water, by wind or, by steam. They may be divided into two kinds: 1st, those by which the motion of the saw is reciprocating; and 2dly, those in which the saws have a rotatory motion. Reciprocating saw mills for cutting timber, and moved by water, do not exhibit much variety in their construction. Fig. 1, in the plate shews the sectional elevation of a saw mill taken from Gray's Experien- ced Millwright. A A the shaft or axle, upon which is fixed the wheel, B.B., of 17% or 18 feet diameter, containing 40 buckets to receive the water which impels it round. C C a wheel fixed upon the same shaft containing 96 teeth, to drive the pinion No. 2; having 22 teeth, which is fastened upon an iron axle or spin- dle, having a coupling box on each end, that turns the cranks, as D D, round. One end of the pole E is put on the crank, and its other end moves on a joint or iron bolt at F in the lower end of the frame G. G. The crank D D being turned round in the pole E moves the frame G G up and down, and these having saws in them, by this motion cut the wood. The pinion. No. 2, may work two, three, or more cranks, and thus move as many frames of saws. No. 3, an iron wheel having angular teeth, which one end of the iron K takes hold of, while its other end rolls on a bolt in the lever H. H. One end of this lever moves on a bolt at I, the other end may lie in a notch in the frame G G, so as to be pushed up and down by it. Thus the catch K pulls the wheel round, while the catch L falls into the teeth, and prevents it from going backwards. . (See UNtveits Al Lever.) Upon the axle of No. 3, is also fixed the pinion No. 4. taking into the teeth in the under edge of the iron bar that is fastencil upon the frame TT, on which the wood to be cut is laid ; by this means the frame TT is moved on its rollers SS, along the fixed frame U U ; and of course, the wood fastened upon it is brought forward to the saws as they are moved up and down by reason of the turning round of the crank D. D. VV, the machine and handle to raise the sluice when the water is to be let upon the wheel B B to give it motion. By pulling the rope at the longer arm of the lever M, the pinion No. 2, is put into the hold or grip of the wheel C C, which drives it; and by pull- ing the rope R, this pinion is cleared from the wheel. No. 5. a pinion containing 24 teeth driven by the wheel C C, and hav- ing upon its axle a sheave, on which is the rope PP, passing to the sheave No. 6, to turn it round; and upon its axle is fixed the pinion No. 7, acting on the teeth in an iron bar upon the frame TT, to roll that frame backwards when empty. By pull- ing the rope at the longer arm of the lever N, the pinion, No. 5, is put into the hold of the wheel C C ; and by pulling the rope O it is taken off the hold. No. 8, a wheel fixed upon the axle No. 9, having upon its periphery angular teeth, into which the catch No. 10, takes: and being moved by the lever attached to the upper part of the frame G, it pushes the wheel No. 8, round; and the catch No. 11. falls into the teeth of the wheel, to prevent it from going backwards, while the rope rolls in its axle, and drags the logs or pieces of wood in at the door Y, to be laid upon the moveable frames TT, and carried forward to the saws to be cut. The catches No. 10, 11, are easily thrown out of play when they are not wanted. The gudgeons in the shafts, rounds of the cranks, spindles and pivots, should all turn round in cods or bushes of brass, Z a door in one end of the mill-house, at which the wood is conveyed out when cut. W W, walls of the mill-house. Q Q, couples or framing of the youth. X X X, &c. windows to admit light to the house. 2. Sawmills for cutting blocks of stone are generally, though not always, moved horizontally; the horizontal alternate motion may be communicated to one or more saws by means of a ro- tatory motion, either by the use of cranks, &c. or in some such way as the following. Let the horizontal wheel A, B, D, C, fig. 2, drive the pinion O p N, this latter carrying a vertical pin P, at the distance of about 4 of the diameter from the centre. This pinion and pin are represented separately in fig. 3. Let the frame W S TV, fig. 2, carrying four saws, marked 1, 2, 3, 4, have wheels W, T, W, W, cach running in a groove or rut, whose direction is parallel to the proposed direction of the saws; and let a transverse groove PR, whose length is double the distance of the pin P. from the centre of the pinion, be cut in the saw frame to receive that pin. Then as the great wheel re- volves, it drives, the pinion, and carries round the pin P; and this pin, being compelled to slide in the straight groove PR, while by the rotation of the pinion on which it is fixed its dis- tance from the great wheel is constantly varying, it causes the whole saw frame to approach to and recede from the great wheel alternately, while the grooves in which the wheefs run. confine the frame so as to move in the direction T t, V v. Other blocks of stone may be sawn at the same time by the motion of the great wheel, if other pinions and frames running off in the directions of the respective radii E B, E A, EC, be worked by the teeth at the quadrantal points B, A, and C. And the con- trary efforts of these four frames and pinions will tend to soften. down the jolts, and equalize the whole motion. The same con- trivance of a pin fixed at a suitable distance from the centre of a wheel, and sliding in a groove, may serve to convert a reci- procating into a rotatory motion; but it will not be preferable to the common conversion by means of a crank. . . - |… - |º º K º, GI | pººr. Hº P- º ºne sºn - | H. | - º i. º, º - |h º |Lºlºl. Tºlºl. - --- - - - -- L-º-n ---> - - S A W. S A W’’ 913.” DICTIONARY OF MECHANICAL SCIENCE. 3. When saws are used to cut blocks of stone into pieces having cylindrical surfaces, a small addition is made to the ap- paratus. See figs. 4 and 5. The saw, instead of being allowed to fall in a vertical groove as it cuts the block, is attached to a lever or beam FG, sufficiently strong: this lever has several holes pierced through it, and so has the vertical piece ED, which is likewise moveable towards either side of the frame in grooves in the top and bottom pieces A. L., D M. Thus the length KG of the radius can be varied at pleasure, to suit the curvature of N O ; and as the saw is moved to and fro by proper machinery in the direction C B, B C, it works lower and lower in the block, while being confined by the beam FG, it cuts the cylin- drical portion from the block P as required. . . When a completely cylindrical pillar is to be cut out of one block of stone, the first thing will be to ascertain in the block the position of the axis of the cylinder; then lay the block so that such axis shall be parallel to the horizon, and let a cylin- drical hole of from one to two inches diameter be bored entirely through it. Let an iron bar whose diametcr is rather less than that of this tube, be put through it, having just room to slide freely to and fro as occasion may require. Each end of this bar should terminate in a screw, on which a nut and frame may be fastened ; the put frame should carry three flat pieces of wood or iron, each having a slit running along its middle nearly from one end to the other, and a screw and handle must be adapted to each slit ; by these means the frame work at each end of the bar may readily be so adjusted as to form equal isosceles or equilateral triangles; the iron bar will connect two correspond- ing angles of these triangles, the saw to be used two other cor- responding angles, and another bar of iron and of wood the two remaining angles, to give sufficient strength to the whole frame. This construction, it is obvious, will enable the workmen to place the saw at any proposed distance from the hole drilled through the middle of the block; and then by giving the alter- nating motion to the saw frame, the cylinder may at length be cut from the block, as required. This method was first pointed out in the Collection of Machines approved by the Paris academy. If it were proposed to saw a conic frustum from such a block, then let two frames of wood or iron be fixed to those parallel ends of the block which are intended to coincide with the bases of the frustum, circular grooves being previously cut in these frames, to correspond with the circumferences of the two ends of the proposed frustum ; the saw being worked in these grooves will manifestly cut the comic surface from the block. This, we believe, is the contrivance of Sir George Wright. he best method of drilling the hole through the middle of the proposed cylinder seems to be this : on a carriage running upon four low wheels let two vertical pieces (each having a hole just Iarge enough to admit the borer to play freely) be fixed two or three feet asunder, and so contrived that the pieces and holes to receive the borer may, by screws, &c. be raised or lowered at pleasure, while the borer is prevented from sliding to and fro by shoulders upon its bar, which are larger than the holes in the vertical pieces, and which, as the borer revolves, press against those pieces: let a part of the boring bar between the two vertical pieces be square, and a grooved wheel with a square hole of a suitable size be placed upon this part of the bar, then the rotatory motion may be given to the bar by an endless band which shall pass over this grooved wheel and a wheel of a mueh larger diameter in the same plane, the latter wheel being turned by a winch handle in the usual way. As the boring proceeds, the carriage with the borer may be brought nearer and nearer the block, by levers and weights, in the same manner as is described under the article Boring of ORDNANce. 4. Circular saws, acting not by a reciprocating but by a rotatory motion, have been long known in Holland, where they are used for cutting wood wanted in veneering. They were introduced into this country, we believe, by General Bentham, and are now used in the dock-yard at Portsmouth, the Royal Arsenal, Woolwich, and in a few other places: but they are not, as yet, so generally adopted as might be wished, consider- ing how well they are calculated to abridge labour, and to accomplish with expedition and accuracy what is very tedious and irksome to perform in the usual way. be ". to turn either in horizontal, vertical, or inclined planes; 5-6. - - Circular saws may and the timber to be cut may be laid upon a plane inclined in any direction; so that it may be sawn by lines making any angle whatever, or at any proposed distance from each other. When the saw is fixed at a certain angle, and at a certain dis- tance from the edge of the frame, all the pieces will be cut of: the same size, without marking upon them by a chalked line, merely by causing them to be moved along and keeping one side in contact with the side of the frame; for then, as they are brought one by one to touch the saw revolving on its axle, and are pressed upon it, they are soon cut through. Mr. Smart, of Ordnance Wharf, Westminster-bridge, has several circular saws, all worked by a horse in a moderate sized walk: one of these, intended for cutting and boring tenons used in this gentleman's hollow masts, is represented in fig. 6. N OPQR is a hollow frame, under which is part of the wheel- work of the horse-mill.—A, B, D, C, E, F, are pulleys, over which pass straps or endless bands, the parts of which out of sight run upon the rim of a large vertical wheel: by means of this simple apparatus, the saws S, S', are made to revolve upon their axles with an equal velocity, the same band passing round the pul- leys D, C, upon those axles; and the rotatory motion is given to the borer G by the band passing over the pulley A. The board I is inclined to the horizon in an angle of about 30 de- grees; the plane of the saw S' is parallel to that of the board I, and about # of an inch distant from it, while the plane of the saw S is vertical, and its lowest point at the same distance from the board I. Each piece of wood K out of which the terion is to be cut is four inches long, an inch and a quarter broad, and # of an inch thick. One end of such piece is laid so as to slide along the ledge at the lower part of the board I; and as it is pushed on by means of the handle H, it is first cut by the saw S', and immediately after by the saw S: after this the other end is put lowest, and the piece is again cut by both saws ; then the tenon is applied to the borer G, and as soon as a hole is pierced through it, it is dropped into the box beneath. By this process, at least 30 tenons may be completed in a minute, with greater accuracy than a man could make one in a quarter of an hour, with a common handsaw and gimblet. The like kind of con- trivance may, by slight alterations, be fitted for many other purposes, particularly all such as may require the speedy saw- ing of a great number of pieces into exactly the same size and shape. A very great advantage attending this sort of machi- nery is, that, when once the position of the saws and frame is adjusted, a common labourer may perform the business just as well as the best workman. Mr. Brunel, a well-known civil engineer, took out a patent for saw-machinery, in May, 1805. The following is an abridg- ment of his specification. The saws are circular, and turn upon an axis passing through their centre. When they are too large to be made with sufficient strength of only one piece of steel, they may be constituted of two, four, eight, &c. pieces, and the joining edge of one plate must be hollow, to receive the sharp edge of that which is to be fitted into it. To augment the strength of the plates, , flanches may be closely fitted to them, several pieces of leather or of paper being interposed, by means of which, and screws duly applied, the whole may be made very firm and strong. The improvements in the machinery for saw- ing timber easily and expeditiously, consist in the modes of laying and holding the piece of wood in the carriage or drag, in the facility of shifting the saw from one cut to another, and in the practicability of sawing both ways either towards or from the saw or saws. Each circular saw is adjusted upon a cylin- drical spindle, which turns within rodings; the motion being communicated by means of a strap or band turning about a proper drum-wheel, and moved by any of the usual actuating powers, as wind, water, steam, animals, &c. The piece of timber being placed upon a drag or carriage, is held fast by means of clamps; and the carriage is moved towards and from the saw by a handle or crank communicating, by the assistance of cog-wheels, to a pinion which engages in a horizontal rack running under the frame of the carriage. This carriage is fur- nished with rollers serving to ease its longitudinal motion, and is intended to be moved by hand, so that its velocity may be varied at pleasure : the length of this carriage must obviously be proportionate to the size of the timber generally cut by the | saw. After the saw has performed one cut, instead of moving 10 Z. 914 S A w S A W DICTIONARY OF MECHANICAL SCIENCE. the timber, the saw itself is moved sidewise, that is, in the direction of its axle, by means of screws, after a method which may be easily conceived, till it is brought to the proper position for the next cut, when an adjusting or fixing screw prevents any lateral motion, and the rotary motion of the saw, and the rectilinear motion of the wood, may be resumed. Circular wedges are used, being intended to revolve by the motion of the log to follow the cut opened by the saw, and by that means to ease the friction, and steady the piece of timber. Sometimes an instrument composed of several parallel plates of metal may be employed instead of the circular wedges. When several saws are adjusted on one spindle, a piece of timber may be converted into planks by being drawn once through under the saws. In that case the flanches of the saws are fixed upon an iron drum, and kept firmly in their relative parallel positions by four bolts. the side rails sustaining their axles may be depressed by means of wedges. The log of wood is not to lie close upon the car- riage or drag, but upon some transverse pieces, which may be moved if requisite when they come near the saw. Some very complete and extensive saw-mills have been recently erected by Mr. Brunel, in the carriage department of the Royal Ar- senal, Woolwich, under the superintendence of Major-General Cuppage and Colonel Miller. Among the numerous purposes for which saws are employed, is that of cutting off the tops of piles. When these are below water, some additional mecha- nism is necessary to cause the saws to work in a horizontal plane at a suitable depth. Different contrivances for this pur- pose, with illustrative engravings, are described by M. Hachette, Traité des Machines, p. 252—275. Saw-Mills are of greater antiquity than is generally supposed. So early as the fourth contury, a saw-mill was erected on the small river Roeur, in Germany: it is probable, however, that this was but a rude contrivance, as we find writers of more modern times, speaking of saw-mills as new and uncommon. The old construction had therefore very likely been lost, or the improvement was so great, as to cause the more modern to be looked upon as new inventions. Saw-mills have been in use more than four hundred years, for upon the discovery of Ma- deira in 1420, mills were erected there for sawing the various excellent timber with which the island abounded. The city of Breslaw had a saw-mill in 1427, which produced a yearly rent of three marks. Erfurt had a saw-mill in 1490. In Norway the first saw-mill was built in 1530. Soon after, the first saw- miil was built in Holstein, another at Joachimstall. In 1555, the Bishop of Ely, ambassador from Queen Mary to the court of Rome, having seen a saw-mill at Lyons, it was thought worthy of a particular description. It was not, however, until the sixteenth century that saw-mills received the great im- provement of having several different saw blades, by which a piece of timber was cut into many planks at the same time. At Saardam, in Holland, were erected a number of saw-mills, where a great many still remain, notwithstanding more than a hundred have been given up of late years. The largest saw- mill ever constructed is in Sweden, where a water-wheel, twelve feet in breadth, drives, at the same time, no less than seventy- two saws. In the seventeenth century, saw-mills were intro- duced into England, attended with the most violent opposition from the sawyers, who apprehended that they would be the means of depriving them of their subsistence. Some that were undertaken were abandoned at the onset, and others were de- stroyed by the populace. The saw-mills of the present day are of two distinct kinds; the circular, those that cut by a conti- nuous rotary motion, and the reciprocating, which operate as the common pit or frame saw. The circular saw-mills are for the most part used for cutting up timber of small dimensions; and the reciprocating for large timber, in forming beams, raf- ters, planks, &c. out of large timber. The most important machinery of the kind was erected by Brunel, under the joint co-operation of Dr. Gregory, at Portsmouth. Eastman's Improved SA w-Mill.—Some important improve- ments have recently been made by Robert Eastman, of Bruns- wick Maine, United States, in sawing machines; the distin- guishing features of which consist in a rotary saw of a superior construction to the common circular saw, and in the improved mamner in which the logs are sawn. Instead of a continued In order to lower the saws as they wear away, series of teeth round the periphery of the plate like other cir- cular saws, Eastman's has only eight, or rather only four cutting instruments (each containing two teeth) placed at equal dis- tances on the circumference, and projecting from it; these instruments are called section teeth. The saving of labour is calculated at full three-fourths, and the surface of the timber is smoother than when cut by the full-teethed saw. On the saw plate are fixed instruments called sappers, which being placed nearer to the centre, do not enter the wood so deeply as the saw, and are adjusted so as merely to cut off the extraneous sap part, rendering thc edges of the planks uniformly straight, and all the cuts of equal dimensions. To understand which, it is, perhaps, necessary here to explain to the reader that the logs are by this machinery cut up lengthwise, not through the log, but from the circumference or exterior to the centre, as the radii of a circle ; it having been ascertained that planks cut in this manner possess more durability, strength, and elasticity, than by the common method. Fig. 7, in the plate, represents a side view of the machine, with a log in it ready for working. Fig. 8, is an end view of the same, exhibiting the log partly cut into sections. Fig. 9, is the saw, with its section teeth L L L L, and its sappers M M. Fig. 10, shews the shape of the sapper, with a groove, or slit, to admit of its being set according to the intended width of the plank. A, fig. 7, is a strong frame of timber, about twenty-four feet long by five broad, the ends of which are seen at AA, fig. 8. B, fig. 7, is the carriage, about twelve feet long and four broad, the ends of which are seen at BB, fig. 8: ; it travels upon iron truck-wheels, grooved on their circumferences, and run upon iron slides, as shewn at K K, fig. 8, C, figs. 7 and 8, gives two views of the log under operation. The log is fixed into the carriage by means of iron centres, upon which it also revolves after each succeeding cut. At D D, figs. 7 and 8, is seen part of the saw. At EP, figs. 7 and 8, are situated the feed pulley and shifting gear. F, regulating pulleys. G, is an index for regulating the dimensions of the cuts. H, revolving levers and pins. I, the pin and fulcrum of the levers. JJ, the stirrup screws and pins. Nearly in the middle of the frame is fixed the main shaft, (of cast iron,) which runs upon friction rollers, supported by stands on the floor. On this shaft is the saw with its sappers and section teeth. The motion is given by a band passing round the main pulley, and round a drum that runs under it; which may be driven by horse, steam, or water power. The method by which the saw is fed with the wood to be cut, and the return of the carriage for the succeeding cut, is too similar to our own to need a particular description. Its various arrangements are ingeniously contrived, and it may be justly termed a self-acting machine, for when once set in motion, no other aid, than the power which drives it, is requisite to its cutting a whole series of boards of uniform dimensions all round the log, having their thin-edged sides attached to the centre piece. These boards being removed, a second series of boards may be cut in like manner to the former, provided the log is big enough. This machine furnishes a new method of manufacturing lum- ber for various useful purposes. Though the circular saw had previously been in operation in this country, and in Europe, for cutting small stuff, it had not, with the knowledge of the writer, been successfully applied to solids of great depth; to effect which, the use of section teeth are almost indispensable. In his first attempts to employ the circular saw for the purpose of manufacturing clap boards, Eastman used one nearly full of teeth, for cutting five or six inches in depth into fine logs. The operation required a degree of power almost impossible to be obtained with the use of a band ; the heat caused the plate to expand, and the saw to warp, or as it is termed, “to get out of true.” To obviate these difficulties, he had recourse to the use of section teeth, and the improvement completely succeeded. The power required to perform a given quantity of work by the other method, was by this diminished at least three-quarters. The work, formerly performed by seventy or eighty teeth, was, by the last method, performed by eight teeth; the sawdust, which before had been reduced to the fineness of meal, was coarser, but the surface of the lumber much smoother than when with the full-teethed saw. The teeth are made in the S A W. S C A 915 DICTIONARY OF MECHANICAL SCIENCE. form of a hawk’s bill, and cut the log up, or from the circum- ference to the centre. The saw may be carried by an eight-inch band, and when driven a proper speed (which is from ten to twelve hundred times per minute) will cut nine or ten inches in depth into the hardest white oak timber with the greatest ease. The sappers at the same time cut off from one to two inches of the sap, and straighten the thick edges of the lumber. The facility with which this saw will cut into such hard materials, may be supposed to result from the well-established principle, that where two substances in motion come in contact, their re- spective action on each other is in direct proportion to their respective velocities; thus a circular plate of iron put into a quick rotary motion, will with great ease penetrate hardened steel, or cut through a file when applied to its circumference; and the same principle is applicable to a saw for cutting wood. The requisite degree of velocity is obtained by the continuous motion of the circular saw ; by which also it has greatly the advantage of one that has but a slow motion on account of dulling, as the teeth are but little affected, and being only eight in number, but a few moments’ labour is required to sharpen them. If the velocity of the saw were slackened to a speed of but forty or fifty times per minute, it would require at least four such bands to carry it through a log as above described. One machine will cut from eighteen to twenty hundred of square feet of pine timber per day, and two of them may be driven by a common tub wheel, seven or eight feet in diameter, having six or seven feet head of water, with a cog-wheel and trundle- head, so highly geared as to give a quick motion to the drums, which should be about four feet in diameter. The machine is so constructed as to manufacture lumber from four to ten feet in length, and from two to ten inches in width, and of any thickness. It has been introduced into most of the New England states, and has given perfect satisfaction. The superiority of the lumber has for three years past been sufficiently proved in Bruns- wick Maine, where there have been annually erected from fifteen to twenty wooden buildings, and for covering the walls of which this kind has been almost universally used. The principal cause of its superiority to mill-sawed lumber, is in the manner in which it is manufactured, viz. in being cut towards the centre of the log, like the radii of a circle ; this leaves the lumber feather-edged in the exact shape in which it should be, to set close on a building, and is the only way of the grain, in which weather-boards of any kind can be manufactured to withstand the influence of the weather, without shrinking, swell- ing, or warping off the building. Staves and heading, also, must be rived the same way of the grain, in order to pass inspection. The mill-sawed lumber, now universally used in the middle and southern states, and in the West Indies, for covering the walls of wooden buildings, is partly cut in a wrong direction of the grain, which is the cause of its cracking and warping off, and of the early decay of the buildings by the admission of moisture. That such is the operation, may be inferred by examining a stick of timber which has been exposed to the weather; the cracks caused by its shrinking all tend towards the heart or centre, which proves that the shrinking is directly the other way of the grain. It follows that lumber cut through or across the cracks, would not stand the weather in a sound state, in any degree to be compared with that which is cut in the same direction with them. One half the quantity of lumber manufactured in this way, will cover and keep tight and sound the same number of buildings for a hundred years, that is now used and consumed in fifty years. Add to this the reduction of expense in transportation, and of labour in putting it on, and we think every one must be convinced that the lumber manufactured in this improved way is entitled to the preference. In manufacturing staves and heading, a great saving is made in the timber, particularly as to heading, of which at least double the quantity may be obtained by this mode of sawing, to what can be procured in the old method of riving it; nor is the straight-grained, or good rift, indispensable for the saw, as it is for the purpose of being rived. The heading, when sawed, is in the form it should be, before it is rounded and dowelled together, all the dressing required being merely to smooth off the outsides with a plane. Timber for staves ought to be straight in order to truss, but may be manufactured so exact in size, as to require but little labour to fit them for setting up. Both articles are much lighter for transportation, being nearly divested of superfluous timber, and may be cut to any thick- ness required for either pipes, hogsheads, or flour barrels. SAY, or SAYe, in Commerce, a kind of serge or woollen stuff, much used abroad for linings, and by the religious for shirts. It is often dyed green, and used for workmen’s aprons. SCAFFOLD, a timber work raised in the manner of an am- phitheatre, to afford a good view of the object or company. SCAP Fold, is also the name of a stage raised for the execu- tion of criminals. It is likewise an elevated temporary assem- blage of poles and boards, to enable builders to attend to their work, in the erection of walls, roofs, &c. SCAGLIOLA, an imitation of marble of any sort. It is hard, and when finished bears a fine polish. It is laid on brickwork like stucco, and worked off with iron tools. The Pantheon, in Oxford-street, London, had all its columns formed of this material ; and when first done, they could scarcely be distinguished from real marble. If preserved from accident, this composition will retain its lustre for many years, without any considerable change of colour, or diminution of beauty. SCALDED CREAM, in rural economy, such cream as is raised by a gentle heat. It is usually called clotted or clouted cream, and is chiefly made in Devonshire and Cornwall, in which counties it is much esteemed. The process is simple. The milk is put into a wide shallow pan, and after standing in it a few hours, the pan is placed over a clear but gentle fire. The cream then collects on the surface, and as the milk gets near boiling, it is taken off and left to cool. The cream is then. skimmed off, and preserved for butter or other uses. SCALE, a mathematical instrument, consisting of several lines, drawn on wood, brass, silver, &c, and variously divided according to the purposes it is intended to serve; whence it ac- quires various denominations, as the plain scale, diagonal scale, plotting scale, Gunter's scale, &c. SCALE, in Music, the denomination first given to the ar- rangement made by Guido, of the six syllables, ut, re, mi, fa, sol, la ; also called Gamut. - SCALES, in Natural History, the covering of fishes, ser- pents, lizards, &c. They are of various kinds, and seem to possess properties analogous to the horns and hoofs of animals. This is indicated by their properties being analyzed, their being cut, and their smell when burned. SCALEs, in Commerce, boards or metallic plates, suspended at the extremities of a beam, for weighing various articles, in order to ascertain their specific gravity and value. SCALENE, atriangle, whose sides and angles are all unequal. SCALING, the act of cleaning the inside of a ship's cannon by the explosion of a small quantity of powder. SCALLION, a species of onion that never forms any bulb at the root. It is generally used green in the spring, before the real onions are ripe. SCALPING, a barbarous custom among Indian warriors, of taking off the enemies’ scalps with the hair on. These are preserved as trophies of prowess and victory; and those who produce the greatest number, receives from the chiefthe highest honours, and most ample rewards. SCALY Diseases, are such as affect the skin, the cuticle dividing into small detached white laminae. The elephantiasis, or leprosy, is of this description. SCAMMONY, in the Materia Medica, a concreted vege- table juice of a plant of the same name. SCANDALUM MAGNATUM, is the special name of astatute, and also of a wrong done to any high personage of the land, as prelates, dukes, marquisses, earls, barons, and other nobles; and also the chancellor, treasurer, clerk of the privy seal, stew- ard of the house, justice of one bench or other, and other great officers of the realm, by false news, or horrible or false mes- sages, whereby debates and discord between them and the com- mons, or any scandal to their persons, might arise. 2 Richard II. c. 5. This statute has given name to a writ granted to re- cover damages thereupon. It is now clearly agreed, that though there be no express words in the statute which give an action, yet the party injured may maintain one on this princi- ple of law, that when a statute prohibits the doing of a thing, which if done might be prejudicial to another, in this case he may have an action on that very statute for his damages. 916 S C A S C : A DICTIONARY OF MECHANICAL SCIENC. E. " SCANDENS, in Botany, is a climbing stem, whether sup- ported by tendrils like the vine, adhesive fibres like ivy, or its own circumvolutions, like the convolvulus and honeysuckle. SCANNING, in Poetry, the measuring of a verse by feet, in order to see whether or no the quantities be duly observed. The term is chiefly used in regard to the Greek and Latin verses. Thus an hexameter verse is scanned, by resolving it into six feet; a pentameter, by resolving it into five feet, &c. - SCANT, is a term applied to the wind when it becomes un- favourable to a ship's course, after having been fair. It is distinguished from a foul wind, as in the former a ship is still enabled to sail on her course, although her progress is consi- derably retarded, but in the latter she is obliged to deviate from it. * • . SCANTLING, the dimensions of any piece of timber with regard to its breadth and thickness. SCANTLING, a measure, size, or standard, by which the dimensions of things are determined. The term is now chiefly applied to timbers, &c. in buildings. - SCAPE GOAT. in Jewish antiquities, the goat which was set at liberty on the day of solemn expiation, typically to bear away the sins of the people. - * contrivance by which the pressure of the wheels which move always in one direction, and the reciprocating motion of the pendulum or balance, are accommodated to one another; when : | letters A FE B. a tooth of a wheel has given the balance or pendulum a motion in one direction, it must quit it, that it may get an impulsion in the opposite direction; and it is this escaping of the tooth of the wheel from the balance or pendulum, or of the latter from the former, whichever we choose to call it, that has given rise to the general term. From the nature of a pendulum, it follows, that it need only to be removed from the vertical, and then let go, in order to vibrate and measure time. Hence it might seem that nothing is wanted but a machinery so con- nected with the pendulum as to keep a register, as it were, of the vibration. It could not be difficult to contrive a method of doing this, but more is wanted; the air must be displaced by the pendulum. This requires some force, and must therefore employ some part of the momentum of the pendulum. The pivot on which it swings occasions friction; the thread, or thin piece of metal by which it is hung, in order to avoid this fric- tion, occasions some expenditure of force by its want of perfect flexibility or elasticity. These, and other causes, make the vibrations become more and more narrow by degrees, till at last the pendulum is brought to rest. We must, of course, have a contrivance in the wheelwork which will restore to the pendulum the small portion of force which it loses in every vibration. The action of the wheels, therefore, may be called a maintaining power, because it keeps up the vibrations. But this may affect the regularity of vibration. If it be supposed that the action of gravity renders all the vibrations isochronous, we must grant that the additional impulsion by the wheels will destroy that isochronism, unless it be so applied that the sum total of this impulsion and the force of gravity may vary so with the situation of the pendulum as still to give a series of forces, or a law of variation, perfectly similar to that of gravity. This cannot be effected, unless we know both the law which regu- lates the action of gravity, producing isochronism of vibration, and the intensity of the force to be derived from the wheels in every situation of the pendulum. Thus it appears that consi- derable scientific skill, as well as mechanical ingenuity, may be displayed in the construction cf scapements; and the judicious consideration of them becomes of great importance to the artist: yet, notwithstanding this, no material improvement was made in them from the first application of the pendulum to clocks till the days of Mr. George Graham ; nothing more was attempted before his time than to apply the impulse of the swing-wheel in such manner as was attended with the least friction, and would give the greatest motion to the pendulum. Dr. Halley discovered, by some experiments made at the Royal Observatory at Greenwich, that by adding more weight to the pendulum it was made to vibrate larger arcs, and the clock went faster; by diminishing the weight of the pendulum, the vibrations became shorter, and the clock went slower; the result of these experiments being diametrically opposite to what ought to be expected from the theory of the pendulum, probably first roused the attention of Mr. Graham, who was not only skilful in practice, but had much mathematical knowledge, and was well qualified to examine the subject scientifically: he soon made such further trials as convinced him, that this seem- ing paradox was occasioned by the retrograde motion, which was given to the swing-wheel by every construction of scape- ment that was at that time in use; and his great sagacity soon produced a remedy for this defect, by constructing a scapement which prevented all recoil of the wheels, and restored to the clock pendulum, wholly in theory, and nearly in practice, all its natural properties in its detached simple state. This scape- ment, with a few others of the most approved construction; will now be briefly described. . 1. The scapement which has been in use for clocks and watches ever since their first appearance in Europe is extremely: simple; and its mode of operation is too obvious to need much explanation. In fig. 1, (see Plate,) XY represents a horizontal axis, to which the pendulum P is attached by a slender rod, or otherwise. This axis has two leaves C and D attached, one near each end, and not in the same plane, but so that when the pendulum hangs perpendicularly, and at rest, the piece C in- SCAPEMENT, among Watchmakers, denotes the general clines a few degrees to the right hand, and D as much to the left. They commonly make an angle of from 70 to 90 degrees: they are called by the name of pallets. A F B represents a wheel turning round on a perpendicular axis E. O., in the order of the The teeth of this wheel are cut into the form of the teeth of a saw, leaning forward, in the direction of the motion of the rim. . As they somewhat resemble the points of an old-fashioned royal diadem, this wheel has got the name of the crown-wheel. In watches it is often called the balance- wheel. The number of the teeth is generally odd, so that when one of them B is pressing on a pallet D, the opposite pallet C is: in the space between two teeth A and I. The figure represents the pendulum at the extremity of its excursion to the right hand, the tooth A having just escaped from the pallet C, and the tooth B having just dropped on the pallet D. It is plain, that as the pendulum now moves over to the left, in the arch P G, the tooth B continues to press on the pallet D, and thus accelerates the pendulum, both during its descent along the arch PH, and its ascent along the arch HG. It is no less evident, that when the pallet D, by turning round the axis XY, raises its point above the plane of the wheel, the tooth B escapes from it, and I drops on the pallet C, which is now nearly perpendicular. I presses C to the right, and accelerates the motion of the pen- dulum along the arch G. P. Nothing can be more obvious than this action of the wheel in maintaining the vibrations of the pendulum. We can easily perceive also, that when the pen- dulum is hanging perpendicularly in the line X H, the tooth B, by pressing on the pallet D, will force the pendulum a little way to the left of the perpendicular, and wili force it so much the further as the pendulum is lighter; and, if it be sufficiently light, it will be forced so far from the perpendicular, that the tooth B will escape, and then I will catch on C, and force the pendulum back to P, where the whole operation will be re- peated. The same effect will be produced in a more remarkable degree, if the rod of the pendºulum be continued through the axis XY, and a ball Q put on the other end to balance P. And, indeed, this is the contrivance which was first applied to clocks all over Europe, before the application of the pendulum. They were balance clocks. The force of the wheel was of a certain magnitude, and therefore able, during its action on a pallet, to communicate a certain quantity of motion and velocity to the balls of the balance. When the tooth B escapes from the pallet D, the balls are then moving with a certain velocity and momentum. In this condition, the balance is checked by the tooth I catching on the pallet C. But it is not instantly stopped. It continues its motion a little to the left, and the pallet C forces the tooth I a little backward. But it cannot force it so far as to escape over the top of the tooth I; because all the momentum of the balance was generated by the force of the tooth B; and the tooth I is equally powerful. Besides, when I catches on C, and C continues its motion to the left, its lower point applies to the face of the tooth I, which now acts on the balance by a long and powerful lever, and soon stops its further motion in that direction; and now, continuing to press on C, it - 2%%amoa. Page 9/6. §. * * F3.3. H. &o.2 & e.S. %. sº -2&cº w *** 22% º º '', ID O & × * 4% %2. e 2- *) 2’ - - - - * - “f* f 22 & Z2 2 G-4/azz/2c222e 4%. 2, ‘O22&ſ. Published by Hisher. Son & Cº. Caxton. London fjec. 1826. S C A S C A DICTIONARY OF MECHANICAL SCIENCE. 917 arges the balance in the opposite direction. Thus we see that in a scapement of this kind the motion of the wheel must be very hobbling and unequal, making a great step forward, and a short step backward, at every beat. This has occasioned the contrivance to get the name of the recoiling scapement, or the scapement of recoil. In this scapement the vibrations are quicker than if the balance or pendulum vibrated freely: for the recoil shortens the ascending part of the vibration, by contract- ing the extent of the arc, and the re-action of the wheel acce- lerates the descending part of the vibration. In this scapement, too, if the maintaining power be increased, the vibration will be performed in larger arcs, but in less time: because the greater pressure of the crown-wheel on the pallet will cause the balance to vibrate through larger arches; and the time will be less increased on this account than it will be diminished by the ac- celeration that pressure gives to the balance and the diminution of the time of recoil. 2. The preceding scapement not being well adapted to such vibrations as are performed through arcs of a few degrees only, another construction has been made, which has been in constant use for about a century in clocks, with a long pendulum beating seconds. In fig. 2, AB represents a vertical wheel called the swing-wheel, having thirty teeth. C D represents a pair of pallets connected together, and moveable in conjunction with the pendulum on the centre or axis F. One tooth of the wheel, as shewn in the figure, rests on the inclined surface of the inner part of the pallet C ; on which its disposition to slide tends to throw the point of the pallet further from the centre of the wheel, and consequently assists the vibration in that direction. While the pallet C moves outwards and the wheel advances, the point of the pallet D of course approaches towards the centre in the opening between the two nearest teeth; and when the acting tooth of the wheel slips off, or escapes from the pallet C, another tooth on the opposite side immediately falls on ſ the exterior inclined face of D, and by a similar operation tends to push that pallet from the centre. The returning vibration is thus assisted by the wheel, while the pallet C moves towards the centre, and receives the succeeding tooth of the wheel, after the escape from the point of D. Thus may the alternation be conceived to go on without limit. In this scapement, as well as the former, the vibrating part is constantly under the influence of the maintaining power, except during the interval of the drop, or actual escape of the wheel from one pallet to the other. One principal recommendation of this scapement seems to have been the facility with which it affords an index for seconds in the face of the clock. Though the pendulum, according to this construction, is constantly connected with the maintaining power in a clock, yet the variations of that power have not the same mischievous effect as in a watch, because the momentum of the pendulum, compared with the impulse of the maintaining power, is prodigiously greater in the former of these instruments. A very considerable change in the maintaining power of a clock with a long pendulum will only cause a variation of a few se- conds in the daily rate. e 3. Mr. Graham’s scapement, already spoken of, was a con- derable improvement upon that just described. He took off part of the slope furthest from the points of the pallets; and instead of that part he formed a circular or cylindrical face, having its axis in the centre of motion. Pallets of this kind are shewn at the lower part of fig. 2, at E and G, having H for their centre or axis. A tooth of the wheel is seen resting upon the circular inner surface of the pallet G, which therefore is not affected by the wheel, excepting so far as its motion, arising from any other cause, may be affected by the friction of the tooth; and this resistance is exceedingly minute, not amount- ing to one-eighth of the pressure on the arch. Nay, we think it appears from the experiments of Coulomb, that, in the case ..of such minute pressure on a surface covered with oil, there is no sensible retardation analogous to that produced by friction, and that what retardation we observe arises entirely from the clamminess of the oil. If the vibration of the pendulum be supposed to carry G outwards, the slope surface will be brought to the point of the tooth, which will slide along it, and urge the pallet outwards during this sliding action. When the tooth has fallen from the point of this pallet, an opposite tooth will be received on the circular surface of E, and will not affect the 95-6. variation, excepting when the slope surface of E is carried out so as to suffer the tooth to slide along it. This contrivance is known by the name of the dead beat, or the dead scapement; because the seconds index stands still after each drop, whereas the index of a clock with a recoiling scapement is always in motion, hobbling backward and forward. In this scapement, an increase of the maintaining power ren- ders the vibrations larger and slower: because the greater pressure of the tooth on the edge of the pallet throws it round through a greater arch : and its increased pressure on both sur- faces of the pallet retards its motion. 4. The effect of the escapement which has been called horizontal, because the last wheel in watches of this construc- tion has its plane parallel to the rest of the system, ig similar to that of the dead beat scapement of Graham. In fig. 5, the horizontal wheel is seen with twelve teeth, upon each of which is fixed a small wedge supported above the plane of the wheel, as may be seen at the letters A and B. On the verge of the balance there is fixed part of a hollow cylinder of steel or other hard material, the imaginary axis of which passes through the pivots of the verge. C represents this cylindrical piece, into which the verge D may be supposed to have fallen. While the vibration causes the cylindrical piece to revolve in the direction which carries its anterior edge towards the axis of the wheel, the point of the wedge will merely rub the internal surface, and no otherwise affect the vibration of the balance than by retard- ing its motion. But when the return of the vibration clears the cylinder of the point of the wedge D, the wheeh will advance, and the slope surface of the wedge acting against the edge of the cylinder will assist the vibration of the balance. When the edge of the cylinder arrives at the outer point of the wedge D, its posterior edge must arrive at the position denoted by the dotted lines of continuation; immediately after which the wedge or tooth E will arrive at the position e, and rest on the outer surface of the cylinder, where it will produce no other effect than that of retardation from friction, as was remarked with re- gard to the wedge D, until the course of the vibration shall bring the posterior edge of the cylinder clear of the point of the wedge. In this last situation, the wedge will act on the edge of the cylinder, and assist the vibration, as in the former case, until that edge shall arrive at the outer or posterior point of the wedge, immediately after which the leading point will fall on the inner surface of the cylinder in the first position, as was shewn in the wedge D. Horizontal watches were greatly esteemed during the last thirty years, until lately, when they gave place to those con- structions which are known by the name of detached or free Scapements. In the common scapement, fig. 1, an increase of the maintaining power inereases the recoil, and accelerates the vibration; but with the horizontal scapement there is no recoil ; and an increase of the maintaining power, though it may en- large the arc of vibration, will not necessarily diminish or alter the time. It is accordingly found, that the experiment of altering the maintaining power by the application of the key does not alter the rate in the same perceptible manner as in common watches. 5. Fig. 6, represents the free scapement of our best portable time-pieces. Fig. 4, exhibits the scapement on a large scale. On the verge of the balance is fixed a circular piece of sap- phire, or of hard steel, E L, out of which a sectoral piece is cut. H G is a straight spring fixed near its extremity H, and having at the other extremity a pin G, against which one of the teeth of the wheel D rests when the train is at rest. This spring has a * slight tendency towards the centre of the wheel,” but is pre- vented by the stop K from throwing the pin further inwards than just to receive the point of the tooth. I is a very slender spring fixed at the end I, and pressing very slightly against the pin G, in a direction tending to throw it from the wheel D, but which on account of the greater power of H G it cannot effect. It may be observed that the spring I proceeds a little beyond the pin G.—F is a lever proceeding from the verge of the balance di- rectly opposite the end of the spring I, and long enough to strike it in its vibration. The action is as follows:—From the pressure of the main spring, the wheel (fig. 4.) is urged from D towards F, but is prevented from moving by the pin G. Let the ba- lance be made to vibrate, and the lever F, will move through 11 A 918 S C A. S C A DICTIONARY OF MECHANICAL SCIENCE. the arc F.f, strike the inner extremity of the spring, I, and dis- place the pin G. At this instant the face E, which may be call- ed the pallet, will have arrived at the position e, against which the tooth of the wheel will fall, and communicate its impulse through about 15° or 16° of the vibration. But F quits the spring I sooner than the wheel quits the pallet E, and consequently the pin G will have returned to its first station before the wheel can have advanced a whole tooth, and the spring or detent H G will receive the wheel as before, immediately after its escape from the pallet. The returning vibration of the balance will be made with the piece EL perfectly at liberty between two teeth of the wheel, as in the sketch, and the back stroke of the lever F against the tender spring I will have no effect whatever on the pin G; this spring being like the back spring of the jacks of the harpsichord, active in one direction only. The third vibration of the balance will unlock the detent as before : the impulse will again be given, and the whole process will be repeated; and in this manner, the balance, though it may vibrate through the greatest part of the entire circle, will be entirely free of the works, except during the very small time of the drop of the wheel. It is hardly necessary to make any remark on this scapement. It requires little or no oil, and when all the parts, particularly the pendulum spring, are duly adjusted, it is found that a very great variation in the first mover will remarkably alter the arc of vibration without affecting the rate. The piece E L might have consisted of a single pallet or arm, instead of a portion of a circle or cylinder; but such a piece would have been rather less convenient to make in Sapphire, or ruby, as in the best time-pieces, and would also have been less useful. For if by any accident or shock, the pin G should be displaced for an in- stant, the wheel D will not run down, because it will be caught upon the circular surface E. L. It is, indeed, very easy to ob- serve, that the piece E L would operate without the detent, though with much friction during the time of repose. The tooth of the wheel would in that case rest upon its circular face. 6. In the two last scapements we have seen the variable ef- fects of the maintaining power almost entirely removed, as far. as can be practically discerned. Fig. 7, exhibits the scapement of Mudge; in which the balance is perfectly detached from the train of wheels, except during the extremely short interval of striking out the parts which serve the purpose of detents. ON E B Q is the circumference of the balance, vibrating by the action of a spiral spring as usual on its axis C A D H passing through the centre C : the axis is bent into a crank, A XY D, to make room for the other work. L. M., ZW, are two rods fixed to the crank at the points L and Z, parallel to X Y c d e f r s are fixed parts of the machine. T R is an axis con- centric with that of the balance, and carrying an arm G o near- ſy at right angles to it, and a small auxiliary spring u, which is wound up whenever the arm G o is moved in the direction o h. p is a curved pallet fixed to the axis TR, which receives the tooth of the balance wheel near the axis. The tooth, pro- ceeding along the curved surface, by the force of the main spring turns the axis and its arm Go, and winds up the spring w. A small projection at the extremity of the curved surface of the pallet p prevents the further progress of the tooth, when the arm o G has been turned through an arc oh, of about 27 ; and consequently the spring w has been wound up through the same angle or arc, o G h = 27°. F S is another axis exactly similar to T. R. It carries its arm Io, and spring v, and the tooth of the balance-wheel l m winds up the spring v, by act- ing on the pallet q, and is detained by a projection, after having carried it through an angle of 27°, exactly as in the former case. The arcs passed through by the arms Go and Io, and marked in the figure, are also denoted by the same letters on the rim of the balance. - The effect of this scapement may be thus explained: let the balance be in the quiescent state, the main spring being un- wound, and the branch or crank in the position represented in the figure. ... If the quiescent points of the auxiliary springs coincide with that of the balance-spring, the arm Go will just touch the rod L M, and in the like manner the arm I O will just touch the rod W Z; the two arms Go and Io in this position are parallel to the line CO. This position of the balance and aux- iliary springs remains as long as the main spring of the ma- chine continues unwound : but whenever the action of the main spring sets the balance wheel in motion, a tooth thereof meeting with one or other of the pallets p or q, will wind up one of the auxiliary springs; suppose it should be the spring w. The arm G. o being carried into the position G h, by the force of the balance wheel acting on the pallet p, remains in that 'position as long as the tooth of the balance-wheel continues locked by the projection at the extremity of the pallet p; and the balance itself not being at all affected by the motion of the arm Go, nor by the winding up of the spring u, remains in its quiescent position ; consequently no vibration can take place except by the assistance of some external force to set the balance in mo- tion. Suppose an impulse to be given sufficient to carry it through the semi-arc O B, which is about 135° in Mr. Mudge's construction. r The balance, during this motion, carries with it the crank A X Y D, and the affixed rods LM, Z W. When the balance has described an angle of about 27° = the angle o C h, or o G h, rod L. M. meets with the arm G. H., and by turning the axis TR, and the pallet p in the direction of the arc O h, releases the tooth of the balance wheel from the projection at the extremity of the pallet p : the balance wheel immediately revolves, and the lower tooth meeting with the pallet q, winds up the auxili- ary spring v, and carries the arm I o with a circular motion through the angle o I k, about 27°, in which position the arm Io remains as long as the tooth of the balance-wheel is locked by the pallet q. While the spring v is winding up through the arc 0 k, the balance describes the remaining part of the semi-arch B, and during this motion the rod L M carries round the arm G h, causing it to describe an angle h CB, or h GB, which is measured by the arc J. B = 108°. When the balance has arrived at the extremity of the semi-arc O B – 135°, the auxiliary spring w will have been wound up through the same angle of 130°, that is to say, 27°, by the force of the main spring acting on the pallet p, and 108° by the balance itself, carrying along with it the arm G. o or G h, while it describes the arc h B. The balance there- fore returns through the arc B O, by the joint action of the balance-spring and the auxiliary spring u; the acceleration of both springs ceasing the instant the balance arrives at the quies- cent point o. When the balance has proceeded in its vibration about 27° beyond the point O, to the position C k, the rod ZW meets with the arm Ik, and by carrying it forward releases the tooth of the balance-wheel from the pallet q. The balance- wheel accordingly revolves, and the upper tooth meeting with the pallet p winds up the auxiliary spring w as before. The balance with the crank proceeding to describe the remaining semi-arc k E, winds up the spring v through the further angle h C E = 108°, and returns through the semi-arc E o, by the joint action of the balance-spring and the auxiliary spring v, both of which cease to accelerate the balance the instant it has arrived at O. - - It may be remarked, in this curious scapement, that the motion of the balance in its semi-vibration from the point of quiescence is opposed through an arc of no more than 108°, but is accelerated in its return through the whole arc of 135°, and that the difference is what maintains the vibrations; and more- over, that the force from the wheel being exerted to wind up each auxiliary spring during the time it is totally disengaged from the balance, this last organ cannot be effected by its irre- gularities, except so far as they may render it more difficult to disengage the rim of the pallet from the tooth. The balance describes an arc of about 8° during this disengagement. Count Bruhl, in his pamphlet “On the Investigation of Astronomical Circles,” after describing Mudge's scapement, proceeds thus: “By what has been said, it is evident, that whatever inequality there may be in the power derived from the main-spring (provided the latter be sufficient to wind up those little pallet-springs), it can never interfere with the regularity of the balance’s motion, but at the instant of unlocking the pallets, which is so instantaneous an operation, and the resistance so exceedingly small, that it cannot possibly amount to any sensible error. The removal of this great obstacle was cer- tainly never so effectually done by any other contrivance, and deserves the highest commendation as a probable means to perfect a portable machine that will measure time correctly. But this is not the only, nor indeed the principal advantage S C A. S C A DICTION ATRY OF MECHANICAL SCIENCE. 919 which this time-keeper will possess over any other; for as it is impossible to reduce friction to so small a quantity as not to affect the motion of a balance, the consequence of which is, that it describes sometimes greater and sometimes smaller arcs, it became necessary to think of some method by which the balance might be brought to describe those different arcs in the same time. If a balance could be made to vibrate without friction or resistance from the medium in which it moves, the mere expanding and contracting of the pendulum-spring would probably produce the so much wished for effect, as its force is supposed to be proportional to the arcs described; but as there is no machine void of friction, and as from that cause, the velo- city of every balance decreases more rapidly than the spaces gone through decrease, this inequality could only be removed by a force acting on the balance, which assuming different ratios in its different stages, could counterbalance that inequality. This very material and important remedy, Mr. Mudge has effected by the construction of his scapement; for his pallet springs having a force capable of being increased almost at pleasure, at the commencement of every vibration, the pro- portion in their different degrees of tension may be altered till it answers the intended purpose. This shews how eſfectually Mr. Mudge's scapement removes the two greatest difficulties that have hitherto baffled the attempts of every other artist, namely, the inequalities of the power derived from the main spring, the irregularities arising from friction, and the variable resistance of the medium in which the balance moves.” 7. Fig. 8, is the sketch of an adaptation of Mudge's scape- ment to a clock. LM is a part of the periphery of the wheel. G A, G B, are two arms separately moveable on the same axis, and terminating in the pallets A, B. These pallets have inclined faces, with a claw or detent at the lower part of each. GO, I O, are tails proceeding from each pallet piece respectively, and the dark spot at N represents a pin proceeding from the pen- dulum rod, and capable of moving either of the tails according to the course of the vibration. The dotted circles w and v represent weights which are stuck upon two pins, and may be changed for others, greater or smaller, until the most suitable quantity is found, Suppose the wheel to be urged from L to- wards M, and the pendulum made to vibrate by external impulse; the pin N proceeding towards L will strike the tail G. O., raise the pallet A, and set the wheel at liberty : which sliding along the inner surface of the pallet B, will raise it, and stop against the claw at its lower end. I O will consequently be carried into the position IP; and the pallet A in its return will be opposite to a vacancy, which will permit the tail G O to follow the pin N as far as the perpendicular situation. The pendulum will there- fore be assisted by the weight w through a longer arc in its de- scent, than it was impeded by it in its ascent. In the opposite semi-vibration toward M, the pendulum will proceed unopposed by v, while it passes through the angle O IP, when it will raise B, and permit the wheel to elevate the pallet A. In the motion on this side of the perpendicular, it is also clear that the descent will be more assisted than the ascent was impeded. Whence it follows, that the clock will continue to go: and no variation of the force of the wheel L. M, which raises the pallets in the absence of the pendulum will affect the vibration, except so far as it may afford a variable resistance at the detent or claw. 8. Mr. Mudge has also given another detached scapement, which he recommends for pocket watches, and executed en- tirely to his satisfaction in one made for the queen. A dead- beat pendulum scapement is interposed between the wheels and the balance. The crutch E D F (fig. 3. has a third arm D G stand- ing outwards from the meeting of the other two, and of twice their length. This arm terminates in a fork A G B. The verge V has a pallet C, which, when all is at rest, would stand be- tween the points A, B, of the fork. But the wheel by its action on the pallet E, forces the fork into the position B g b, the point A of the fork being now where B was before, just touching the cylindrical surface of the verge. The scapement of the crutch E D F is not accurately a dead-beat scapement, but has a very small recoil beyond the angle of impulsion. By this circum- stance the branch A (now at B) is made to press most gently on the cylinder, and keeps the wheel locked, while the balance is going round in the direction B H.A. The point A gets a motion from A to B by means of a notch in the cylinder, which turns round at the same time by the action of the branch A G on the pallet C ; but A does not touch the cylinder during this motion, the notch leaving free room for its passage. When the balance returns from its excursion, the pallet C strikes on the branch A (still at B), and unlocks the wheel. This now acting on the crutch-pallet F, causes the branch b of the fork to follow the pal{et C, and give it a strong impulse in the direction in whieh it is then moving, causing the balance to make a semi-vibration in the direction A H B. The fork is now in the situation Ag a, similar to Bg b, and the wheel is again locked on the crutch pallet E. The intelligent reader will admit this to be a very steady and effective scapement. The lockage of the wheel is procured in a very ingenious manner; and the friction on the cylinder, necessary for effecting this, may be made as small as we please, notwithstanding a very strong action of the wheel; for the pressure of the fork on the cylinder depends entirely on the degree of recoil that is formed on the pallets E and F. Pressure on the cylinder is not indispensably necessary, and the crutch- scapement may be a real dead-beat. But a small recoil, by keeping the fork in contact with the cylinder, gives the most perfect steadiness to the motion. The ingenious inventor, a mars of approved integrity and judgment, declares that her majesty’s watch was the best pocket-watch he had ever seen. We are not disposed to question its excellency. - 9. Another scapement, in which a considerable degree of ingenuity is united with comparative simplicity, is that of Mr. De Lafons. The inventor's description and some of his obser- vations, as presented to the Society of Arts, are as follows:– Although the giving an equal impulse to the balance has been already most ingeniously done by Mr. Mudge at d Mr. Halley (from whose great merit we would not wish to detract,) yet the extreme diſficulty and expense attending the first, and the very compound locking of the second, render them far from completing the desired object. The perfections and advan- tages arising from my improvements on the remontoire de- tached scapement for chronometers, which gives a perfectly equal impulse to the balance, and not only entirely removes what- ever irregularities arise from the diſſerent states of fluidity in the oil, from the train of wheels, or from the main spring, but does it in a simpler way than any with which I am acquainted. I trust it will not be thought improper in me to answer some objections made at the examinations before the committee, as I am fully persuaded the more mathematically and critically the improvements are investigated, the more perfect they will prove to be. It was first observed that my method did not so completely detach the train of wheels from the balance as an- other scapement then referred to. I beg leave to remark, that the train of wheels in mine is prevented from pressing against the locking by the whole power of the remontoire-spring : so that the balance has only to remove the small remaining pressure, which does away that objection, and also that of the disadvan- tage of detents, as this locking may be compared to a light ba- lance turning on fine pivots, without a pendulum spring ; and has not only the advantage of banking safe at two turns of the balance, and of being firmer and less liable to be out of repair than any locking where spring work is used, but likewise of unlocking with much less power.—It was then observed, it required more power to make it go than usual. Permit me to say, it requires no more power than any other remontoire- scapement, as the power is applied in the most mechanical manner possible.--And, lastly, it was said, that it set or requir- ed the balance to vibrate an unusually large arch before the piece would go. This depends on the accuracy of the execu- tion, the proportionate diameter and weight of the balance, the strength of the remontoire-spring, and the length of the pallets. If these circumstances are well attended to, it will set but little more than the most generally detached Scapements. A, fig. 9, shews the scape wheel; B, the lever-pallet, on an arbor with fine pivots, having at the lower end, C, the remontoire or spi- ral-spring fixed with a collar and stud, as pendulum-springs are ; D the pallet of the verge, having a roller turning in small pivots for the ſever pallet to act against; E. pallets to discharge the locking, with a roller between, as in fig. 10; F, the arm of the locking-pallet continued at the other end to make it poise. having studs and screws to adjust and bank the quantity of 320 S C A S C H DICTIONARY OF MECHANICAL SCIENC E. motion ; a, and b, the locking pallets, being portions of circles fastened on an arbor turning on fine pivots; G, the triple fork, at the end of the arm of the locking pallets. The centre of the lever pallet in the draft, is in a right line between the centre of the scape wheel and the centre of the verge, though in the model it is not; but may be made so or not, as best suits the calliper, &c. The scape-wheel A, with the tooth I, is acting on the lever- pallet B, and has wound up the spring C ; the verge pallet D (turning the way represented by the arrow) the moment it comes within the reach of the lever pallet, the discharging pallet E, taking hold of one prong of the fork, removes the arm F, and relieves the tooth p from the convex part of the lock a. The wheel goes forward a little, just sufficient to permit the lever-pallet to pass, while the other end gives the impulse to the balance ; the tooth 4 of the wheel is then locked on the con- cave side of the lock b, and the lever-pallet is stopped against the tooth 5, as in fig. 11. So far the operation of giving the impulse, in order again to wind the remontoire spring (the other pallet at E, in the return removing the arm F the contrary direction), relieves the tooth 3 from the lock b. The wheel again goes forward, almost the whole space from tooth to tooth, winds the spiral spring again, and comes into the situation of fig. 1, and thus the whole performance is completed. The end of the lower pallet B resting on the point of the tooth 1, pre- vents the wheel exerting its full force on the lock a, as in ſig. 1, The same effect is produced by the pallet lying on the tooth 5, by preventing the wheel from pressing on b ; and thus the lock- ing becomes the tightest possible. This scapement may be much simplified by putting a spring with a pallet made in it as in fig. 12, instead of the lever pallet, and spiral-spring. The operation will be in other respects exactly the same, avoiding the friction of the pivots of the lever-pallet. This method I prefer for a piece to be in a state of rest, as a clock; but the disadvantage from the weight of the spring in different positions, is obvious. The locking may be on any two teeth of the wheel, as may be found most convenient.—Dr. Gregory’s Mechanics. Many other ingenious scapements have been contrived by Harrison, Hindley, Ellicott, Lepaute, Le Roy, Berthoud, Ar- mold, Whitehurst, Earnshaw, Nicholson, &c. But descriptions of them would extend this article to much too great a length. What is here collected will, we trust, furnish some insight into the nature of a few of the most approved scapements. SCAPHISM, an unseemly torture among the ancient Per- sians, by which criminals were exposed to be stung to death by WalSOS, §§polite, a mineral found at Arendal in Norway. It is of a pearl colour, and is crystallized in long, four-sided rectan- gular prisms. Faces longitudinally streaked. Its specific gra- vity is 3:68, and it is hard enough to scratch glass. SCARA BAEUS, in Natural History, the Beetle, a genus of insects of the order coleoptera. In this genus there are several hundred species, in four divisions, which are distinguished by the form of their feelers. The beetle is the most remarkable species, as well in size as in beauty. It is five or six inches long; the wing-shells are of a smooth surface, of a bluish-gray colour, marked with round deep-black spots of different sizes. In this country, the cockchafer is very common. The larva inhabits ploughed lands, and feeds on the roots of corn; and the complete insect makes its appearance during the middle and the decline of summer. The larva of this insect is eagerly sought after and devoured by swine, bats, crows, and poultry; it is said to be two or three years in passing from its first form into that of the perfect insect. A species of great beauty is the golden beetle, about the size of the common or black garden beetle ; the colour is most brilliant, varnished, and of a golden green. This is a fine object for the magnifying glass. It is not very uncommon during the hottest parts of summer, frequent- ing various plants and flowers; its larva is commonly found in the hollows of old trees, or among the loose dry soil at their roots, and sometimes in the earth of ant hills. SCARFING, a sea term, a particular method of uniting two pieces of timber together by the extremities, so that the end of one goes over the end of the other, being tapered so that the one may be set into the other, and become even, as the keel- pieces. But when the ends of the two pieces are cut square and put together, they are said to butt to one another, (see tire article BUTT ;) and when another piece is laid on and fastened to both, as is the case in all the frame timbers, this is called scarfing the timbers, and half the piece which fastems the two timbers together is reckoned the length of the scarf. SCARIFICATION, in Surgery, the operation of making se- veral incisions in the skin by means of lancets, or other instru- ments, particularly the cupping-instrument. SCARLET, a beautiful bright red. SCARP, in Fortification, the interior slope of the ditch with which the fortification is surrounded, and faces the country or champaign. SCAVAGE, a toll or custom anciently exacted by mayors, sheriffs, and bailiffs of cities and towns-corporate, and of mer- chant strangers, for wares exposed and offered to sale within their liberties, which was prohibited by 19 Hen. VII. But the city of London still retains this custom. SCAVENGERS, two officers chosen annually in each parish in London and the suburbs, whose business it is to see that the streets are kept clean, under a penalty of forty shillings for each offence. f SCELOTYRBE, a disease characterized principally by a contraction of the limbs. For this, various causes have been assigned. SCENE, in a primary sense, denotes a theatre, where dra- matic pieces, and other public shows, were represented. Its application is now extended to picturesque views of almost every description. SCENOGRAPHY, in Perspective, the perspective repre- sentation of a body on a plane ; or a description and view of it in all its parts and dimensions, such as it appears to the eye in any oblique view. SCENOPEGIA, a grand festival among the Jews, at which all their males of a given age were to attend at their national altar. It is more generally called “the feast of tabernacles.” SCENT, in Hunting, the effluvia thrown off by animals in the chase, and by which they are followed through all their mazes and retreats, by dogs and those who follow them. So acute is the sense of smelling in these hounds, that carcases buried with lime ten feet under ground, have been known to attract them to the spot. The term scent, in a lax sense, is sometimes applied to things highly offensive to the olfactory nerves, but frequently to aromatics, and agreeable odours. SCEPTIC, one who embraces scepticism, and sometimes affects to doubt his own existence. º SCEPTICISM, doubt, hesitation, indecision, unbelief. Scep- ticism professes to weigh every thing, but it determines nothing. It robs the mind of its resting-place, but substitutes nothing in its stead, - e - SCHEDULE, a scroll of parchment or paper, annexed to a deed, will, or other instrument, containing an inventory of . goods, &c. omitted in the body of the will or deed. It is used particularly for the statement of effects delivered by a bankrupt to the commissioners who are appointed to investigate his affairs. It also includes a list of such articles as are the sub- jects of taxation. - - SCHEIK, a name given by the Turks to the prelates of the Mahometan religion, who pretend to be the legitimate succes- sors of Mahomet. Their chief resides at Mecca. SCHEME, representation of any geometrical or astronomical figure, or problem, by figures sensible to the eye; and also the harmonious result of contrivance and ingenuity. SCHIECH, in Arabia, an officer of high birth, which can only come by descent, and is peculiar to princes, sovereigns, and independent lords. Among the Bedouins, this title belongs to every noble. SCHIRROSIS, a name given to a disorder in the eyes, arising, from a long continued inflammation, when the flesh increases in bulk, and assumes a livid colour. SCHISM, literally, a cleft or fissure. In Religion, to which the term is chiefly applied, it means a separation among per- sons who profess the same general principles of faith, but differ in some subordinate particulars. The Romanists enumerate thirty-four schisms that have taken place in their church, among which, the ecclesiastical revolution that took place in the days of Luther, holds a prominent rank. The Reformation S C { S (; I 921 DICTIONARY OF MECHANICAL SCIENCE. that took place in this country is called the English schism; and the English church, in its turn, applies the opprobrious epithet to Presbyterians, Independents, Anabaptists, and Methodists; while each of these sects cry out Schism against all who secede from their respective communities. . SCHISTUS, in Mineralogy, a name given to several differ- ent kinds of stones, but more especially to some of the argil- laceous kind. - SCHOLASTIC, something belonging to the schools, or taught in them. Connected with Philosophy, it is a name given to the dialectic of Aristotle. From the fifth until the twelfth century, scholastic philosophy was held in high esteem. The Reforma- tion inſlicted on it a deadly wound, so that at present it is little studied, and less regarded. - Scholastics, persons who study either scholastic philoso- phy or divinity. - - - SCHOLIUM, a note, annotation, or remark; occasionally made on some passage or proposition of an old author. SCHOOL, a public place in which languages, arts, and sciences, are taught. Schools vary in character and degree, according to the subjects introduced, from the elementary prin- ciples of words, to the result of academic researches, and the learning inculcated in the most renowned universities. In the management of schools considerable improvements have been made of late years, but more generally in their lower depart- ments. The word Schola originally signifies discipline and cor- rection, and it was anciently used to designate all places where persons met together either to study, to converse, or to do | any other matter. Among the Hebrews, the synagogues suc- ceeded the schools of the prophets. The Charity Schools in England are both numerous and opulent, but replete with abuses. Winchester, Eton, and West- minster schools, are royal foundations. All the other grammar schools, as they are termed, are, in fact, charity Schools, though of a higher class than the parish Schools for the education of our pauper youth. Sunday Schools, another species of charity schools, have many advocates, as have also the National Schools; and were they universally adopted, we might expect to see the morality of the nation keep pace with these benevolent institutions. Juvenile offenders, without doubt, are numerous; but our gaols are under no obligations to Sunday Schools for their inmates. SCHOONER, a small vessel with two masts, whose main- sail and foresail are both suspended by gaffs, like a sloop's mainsail. SCHORL, a mineral which derives its name from Schorlaw, in Saxony, where by him it was first discovered. SCIARRI, the matter which runs in burning torrents from the craters of volcanoes. - SCIATHERICUM, a horizontal dial, with a telescope adapted for observing the true time, both by day and by night, to regulate and adjust pendulum clocks, watches, and other time-keepers. SCIATIC STAY, a strong rope fixed from the main to the foremast heads in merchant ships: when loading or unloading, it serves to sustain a tackle, which travelling upon it, may be shifted over the main or fore hatch ways, as occasion requires. SCIENCE, in Philosophy, a clear and certain knowledge of any thing, founded on demonstration, or self-evident prin- ciples. . • * Sciences, General Enumeration of the.—PRINCIPLes of all things—ELEMENTS which these principles originate—Bei NGs which these elements form—ORGANs which these beings deve- lop—WANTs which these organs experience — SIGN's which these wants excite—SocIETIES which these signs produce— Count Ries which these societies inhabit—EARTH which these countries compose—PLANETARY SYSTEM to which this earth belongs. Here the accurate observer will, perhaps, allow the implicit dependence of each succeeding on each preceding head; and if we next shew, that, under these heads, every individual science as naturally arranges itself, he will perhaps also grant, that we have traced the basis of a natural system. We shall, accordingly, place these ten successive and depen- dent heads in the first column of the following table, and range after each, in the third column, the triple science which it involves. 95-6. General Particular Names of the Including, amongst others, Heads. | Subjects. Sciences. the following Branches. . Matter, Space, - ſ Motion.* }Metaphysics. tº g Extension, Divi- \ Principles i sibility, &c. ;Pa YSICS.f Arithmetic, Geometry, ! Number, Form, R Algebra, & gebra, C&C. C Magnitude.* {Mathematics, ; (Atoms, ATo MoLog Y — the doctrines of Heat, | Light, Sound. tº Elements. < Molecules, CHEMISTRY — Electricity, Galvanism, wº Magnetism. | Masses, MECHANICS — Statics, Hydrostatics, Pneumatics. Minerals, MINERALOGY. Beings. } Vegetables, BotANy. Animals, ZOOI.OGY. Forms, PHYSIoGNOMY. Organs. {º. ANATOMY. Actions, PHYSIOI. oGY. Clothing, Costiſ M.E. Wants. }: GARDENING, &c. Shelter, ARCHITECTUB E. r LANG & * * , e. Speech, #;" Ronanºpºlº MUSIC, ty e. GESTURE. Signs. < Gesture, }; PA1NTING. LETTERS. Writing, SYMBOLS. & HIEROGLYPHICS. f rfamilies, MORALS — Manners, and the s Drama. Societies. ! Cities, CIVICS *º-º sº |Num, POLITICS — the relations of Peace, - Diplomacy, War. Land, GEOGRAPHY — Geology and Palaeon- g tography. Countries. }: HYDROGRAPHY. ppy Air, AEROLOGY — Meteorology. Its Form, &c. Earth. } Its motion, COSMOGRAPHY, Its Effects, Planetary * 4. Forms, &c. System. ºneir Motions, ASTRONOMY. Their Influence, * The subjects of these three lines differ considerably ; but under Meta- physics, Physics as here employed, and Mathematics : they are all consi- dered abstractly, and it is in that sense that we apply to them the general term—Principles. # Extension, Divisibility, &c. are only the first subjects commonly placed under this head. We use the term in a limited sense. It is commonly used in a vague manner. # Including the doctrines of property and money, as well as of population. SCIENTIFIC, something relating to the pure, sublime sciences, or that abounds in science or knowledge. A work is said to be scientifical, when it is founded on the pure reason of the thing, or conducted wholly on their principles. SCIERIA, a festival kept in Arcadia in honour of Bacchus. SCILLA, the Squill, in Botany, a genus of the monogynia order, in the hexandria class of plants, and in the natural me- thod ranking under the 10th order, coronariae.—22 species. SC1M PODIUM, an ancient bed or couch, adapted for one person only. It was also used instead of the Lectica, to carry both men and women, not only through the city, but likewise in journeys into the country. SCINCUS, a species of lizard, sometimes called the Croco- dile, and formerly well known in the shops of the druggists as an ingredient in several compositions. SCIOPTIC BALL, a sphere or globe of wood, with a circular hole or perforation, in which a lens is placed. It is so con- trived, that, like the eye of an animal, it may be turned round every way, and is used for making experiments in darkened TO O Úl S. * SCIRE FACIAS, is a judicial writ, and properly lies after a year and a day after judgment given; whereby the sheriff is 11 B * 922 S C O S C O DICT10NARY OF MECHANICAL SCIENCE. commanded to summon or give notice to the defendant, that he appear and shew cause why the plaintiff should not have exe- cution. l Inst. 290. SCIRRH US, in Surgery, a term that denotes any kind of swelling, accompanied with considerable hardness. SCIRRONES, a species of small lice bred under the skin. SCIRROPHORION, the last month of the Athenian year. It contained twenty-nine days, and corresponded with the latter part of our May and beginning of June. SCITAMINEA, in Botany, an important order of plants, the eighth among the Fragmenta of Linnaeus. SCIURUS, the Squirrel, in Natural History, a genus of mam- malia, of the order gillires. These animals live principally on seeds and fruits. They are extremely active and nimble, climb- ing trees with great rapidity, and bounding from one to another with a spring truly astonishing. Some are supplied with mem- branes, which enable them to extend this leap into something approximating to a short flight. Some are subterraneous, and others build in trees. They are sprightly, elegant, and interest- ing. The sailing squirrel is an inhabitant of Java and the Indian islands, and can spring to an immense distance from | tree to tree, by means of a membrane similar to that of the pre- ceding, which is extremely thin in the middle, and thicker to- wards the extremities. This is the largest of all the flying squirrels, and is eighteen inches long, exclusively of the tail. SCLEROTICA, in Anatomy, one of the tunics, or coats of the eye. SCNIPS, a small species of gnat found about the oak, and sustained by the juices of its leaves. SCOBS, the raspings of ivory, hartshorn, or other hard sub- Stan CeS. SCOLD, CoMMON, a turbulent woman, liable to be indicted, and punished as a public nuisance. In the Saxon laws this punishment was the cucking-stool, now corrupted into the ducking stool. SCOLEX, a genus of the Vermes intestina class and order. SCOLIA, a genus of insects of the order hymenoptera. Sco LIA, songs of the ancient Greeks. SCOLOPAX, the Curlew, in Natural History, a genus of birds of the order grillae. There are fifty species, of which the following are the chief: The common curlew, generally about two feet long, is to be met with in England throughout the year, either on the coasts or near the mountains. Slugs and worms, which its bill extracts from the ground in the morning and evening, constitute its inland subsistence; and when on the shores of the sea, it feeds on marine animals. These birds are often observed in large flocks, and are used by many for food. Those killed on the coasts, however, are rank and fishy.—The woodcock is about fourteen inches in length, migratory in this country, and supposed to proceed from Swe- den.—The snipe, weighs about four ounces, is about twelve inches long, and to be found in nearly every country of the world. Its food consists of worms and insects, which it seeks near small streamlets and in general in wet grounds.—The com- mon godwit, is of the weight of twelve ounces, and ranks in the highest order of delicacies.—The redshank, is not uncommon in this island, and particularly towards the south. SCOLOPENDRA, in Natural History, centipede, a genus of insects of the order aptera. There are thirteen species found in almost all parts of the world; they live in decayed wood, or under stones, and some of them in fresh and salt water ; they prey on other insects. The larger species are found only in the hotter regions of the gobe; they are insects of a terrific appearance, and possess the power of inflicting severe pain and inflammation by their bite. SCOM BER, the Mackarel, in Natural History, a genus of fishes of the order thoracici. There are twenty-one species, of which we shall notice the following:—The common mackarel. This is one of the most beautiful of fishes, and inhabits both the European and American seas. The mackarel is a fish highly admired both for its beauty and excellence, and has in every age attracted particular notice and partiality from both these circumstances. The Romans prepared from it a condiment of essence for the table, which was in the highest estimation. The general length of this fish is fifteen inches, but specimens far larger have been occasionally met with.-The tunny is some- times ten feet long, and on the Scotch coast one was taken which weighed four hundred and sixty pounds. In the Indian ocean...it is said to exceed even this enormous size. These fishes are not particularly admired for food in this country, in which, indeed they are rarely seen approaching the British coast only in straggling parties, or rather as solitary individuals. By the ancients, fisheries were established for taking and pre- serving them, on the coasts of the Mediterranean, in which sea they particularly abound, and there are at present on the same coasts very extensive establishments for this purpose. Indeed, to the inhabitants on those shores, the movements of tunny are watched and expected with as much eagerness as those of the herring or mackarel in the north. The small fishes are gene- rally carried fresh to market, and the large ones are cut up into pieces of a particular size, and preserved in salt in barrels. The tunny is a very voracious fish, and a great persecutor of the common mackarel. SCOOP, a little hollowed piece of wood employed to throw the water out of a boat, which operation is usually called baling the boat. SCORE, in Music, the original and entire draught, or its transcript, of any composition. SCORIA, or DRoss, is that mass which is produced by melt- ing metals and ores, and when cold is brittle, and not inso- luble in water; being properly a kind of glass. SCORING, the art of forming a score by collecting, and pro- perly arranging under each other, the several detached parts of any composition. SCORPIO, the Scorpion, mu, is the eighth sign in the order of the zodiac, and the second of the southern signs. The sun enters it on the 23d of October, according to the fixed and intellectual zodiac of Hipparchus and the moderns; but if we follow this sign in the recession of Aries and his train, we shall find that the sun enters Scorpio about the 20th of November. The ancient poets of Greece tell us, that this is the Scorpion which Diana sent to wound Orion for usurping her office. Ovid tells us, that this serpent was produced by the earth, to punish Orion's vanity for having boasted that there was not on the terraqueous globe any animal which he could not conquer. Again, it is said that Autumn, which produces fruits in great abundance, brings with it a variety of diseases; and this season is very fitly represented by a Scorpion, which wounds with its tail as it recedes. Boundaries and Contents.—Scorpio is bounded on the north by Serpentarius and Serpens; east by Sagittarius; south by Lupus, Norma, and Ara; and west by Libra : but the tail of Scorpius does not rise at London. In this sign there are forty- four stars, of which, one is of the first magnitude, one of the second, eleven of the third, eighth of the fourth, &c. Antares, called also Cor Scorpii, of the first magnitude, rises on the south-east point of the horizon at London. Its declination is 26° 1' 10" south ; its right ascension, 244° 35' 36"; and it rises and culminates as in the following table : Meridian altitude 12o 27' 50". MONTH. | RISES. CULM. MONTH. RISEs. CULM. - ho. mi. ho. mi. ho. mi. ho. mi. Jan. 6 0 M. 9 28 M. July 6 15 A. | 9 37 A. Feb. || 3 45 M. 7 16 M. Aug. | 4 || 5 A. | 7 33 A. Mar. 2 0 M. 5 28 M. Sept. 2 15 A. | 5 37 A. April | 12 10 M. 3 34 M. ()ct. I 2 25 A. | 3 49 A. May | 10 25 A. 1 43 Ml. Nov. 10 25 M. I 53 A. June S 25 A. | 11 41 A. Dec. 8 15 M. l l l 4G M. Scorpio, in Natural History, a genus of insects of the order Aptera. There are ten species, all of which are armed with a slightly pungent sting; and in hot climates some of them are highly dangerous : they prey upon worms, spiders, flies, &c. and even on one another. SCORPION, in the ancient art of war, an engine chiefly used in the defence of the walls of ſortified places by throwing arrows, fireballs, or great stones. - SCOT, a customary contribution laid upon all subjects according to their abilities. Whoever were assessed to any contribution, though not by equal portions, were said to pay scot and lot. - SCOTCH FIR, common fir, or pine tree. S C R. S C R. 923 DICTIONARY OF MECHANICAL SCIENCE. SCOTCHES, in Agriculture, a term signifying scores or notches. It is sometimes employed as a mode of reckoning, by farmers. SCOTES, a species of duck, sometimes called the black diver. SCOTIA, in Architecture, a semi-circular cavity or channel, between the tores in the bases of columns. SCOTISTS, a sect of school divines and philosophers, so called from J. Duns Scotus, their founder, who flourished in the fourteenth century, but they are now unknown. SCOTLAND. By 5 Anne, c. 8, the Union of England and Scotland was effected, and the twenty-five articles of union, agreed to by the parliaments of both nations, were ratified and confirmed as follows: viz. the succession to the monarchy of Great Britain shall be the same as before settled with regard to that of England. The united kingdoms shall be represented by one parliament. There shall be a communication of all rights and privileges between the subjects of both kingdoms, except where it is otherwise agreed. When England raises £2,000,000 by land-tax, Scotland shall raise £48,000. The standards of the coin, of weights and measures, shall be reduced to those of England throughout the united kingdoms. The laws relating to trade, customs, and excise, shall be the same in Scotland as in England. But all the other laws of Scotland shall remain in force, though alterable by the parliament of Great Britain ; and particularly, laws relating to public policy are alterable at the discretion of parliament. Laws relating to private right are not to be altered, but for the evident utility of the people of Scotland. Sixteen peers are to be chosen to represent the peerage of Scotland in parliament, and forty-five members to sit in the house of commons. The sixteen peers of Scotland shall have all privileges of parliament, and all peers of Scotland shall be peers of Great Britain, ranking next after those of the same degree at the time of the union, and shall have all privileges of peers, except sitting in the house of lords, and voting on the trial of a peer.— It was formerly resolved by the house of lords, that a peer of Scotland, claim- ing and having a right to sit in the British house of peers, had no right to vote in the election of the sixteen Scotch peers; and that if any of the sixteen Scotch peers are created peers of Great Britain, they thereby cease to sit as representatives of the Scotch peerage, and new Scotch peers must be elected in their room. SCOUR, in Military language, is to flank a line in such a manner as to go directly along it, so that a musket ball, enter- ing at one end, may reach to the other, leaving no place of security. SCOURING, among cattle, is a disease of the flux kind, which frequently proves mortal. Sheep are not exempt from its influence. Scouring, among Farriers, is a gentle purge, to preserve animals from noxious humours. SCOUTS, in Military language, are generally horsemen sent out either before, or on the wings of an army, at the distance of i. or two, to discover the enemy, and give some signal of ala III]. SCRAPER, an instrument used in mezzotinto engraving, formed much in the manner of a knife, except towards the point, where it slopes off at an angle from both sides. In com- mon language, the application of the term to numerous utensils is well known. SCRAPER, Shipcarpenter's,” is an iron machine, having two or three sharp edges, used to serape off the dirty surface of the planks on a ship’s side, or decks, or to clean the topmasts, &c. When the sides of a ship are thus sufficiently scraped, they are varnished over with turpentine, or a mixture of tar and oil, &c. which prevents the planks from being rent or split by the sun or wind. SCRATCH, the name of a calcareous, earthy, or stony sub- stance, which separates it from sea water in boiling it for salt. This concretion, which forms itself on the sides and bottoms of the pans to which it adheres, is the same substance that crusts over the inside of our tea-kettles. It is a species of spar sus- tained more or less in all water, from which it is detached by boiling. ScRATCH es, a disease in horses, consisting of dry chops, scabs, or rifts, that are generated between the heel and the ps stern joint. •. ScRAtch Work, a way of painting in fresco. It is rough, but lasting, and is chiefly used to embellish the fronts of mag- nificent buildings. SCREEN, in domestic comfort, an instrument for keeping off the wind, or the excessive heat of the fire. In Building, Screen is used as a frame of laths, for sifting earth, lime, or sand. In Agriculture, Screen, among farmers, is a contrivance made chiefly of wires in a frame, for the purpose of separating grain of various kinds from seeds of weeds with which it was pre- viously mixed. SCREEN, is the name given to the pieces of canvass, or hammock, hung round a birth for warmth and privacy. SCREW, one of the mechanical powers. See MechANicAl Power Machine for Making an original and perfect Screw.—This machine was invented by Mr. Angus Mackinnon, Glasgow. Fig. 1 is a plan, and fig. 2 is an end view of the machine for constructing the screw. A A is the cast-iron bar, upon which Fig. 1. d K the die-frame B B is made to move; c c c c, two strong springs attached to the die-frame, having rollers, d d dd, in each end, moving upon the angular parallel edges of the bar A A. E., a small frame for holding the cutter; the cover being removed, to shew the action of the cutter upon the steel cylinder, of which the screw is to be made. F, the steel cylinder; the point of the cutter, (which must be adjusted to an angle, varying accord- ing to the pitch of thread wanted,) is seen projecting from the Frº. 2. () () frame E, being pressed forward by the screw G. One end of the cylinder F acts upon the centre in the head-stock I. The journal upon the other end of the oylinder works into the steel collar V. k k h k, four small screws for pressing forward the springs c ce c. 11 ll, four small eyes in the die-frame, to which cords are attached, passing over the pulleys m 'm mm; weights 924 S C U S C R. DICTIONARY OF MECHANICAL SCIENCE. punishable by fine and imprisonment. being hooked on at the other ends of the cords, sufficient to overcome the friction of the die-frame. N, the handle to turn the cylinder. - In beginning to make the screw, the two weights to the left are hooked on to the ends of the cords, and the cylinder is turned round by the handle, until the cutter traverses the length of the cylinder, when the weights are removed to the cords on the right hand. By continuing this operation alternately from right to left, an original and perfect screw is produced, as ex- hibited in fig. 3. In the end view of the machine, fig. 2, o o represents one of the feet by which it is fastened to a bench. The same letters refer to the same parts of the machine in both figures, where those parts are exhibited. Having obtained, as already described, one screwed cylinder ; this is removed, and another of the same size is put into the machine. operation is performed on it as on the last; but it is not screwed to a full thread, the sharp cutter being removed when the spaces and threads are of an equal size, and a square cut- ter is put in its place, by means of which is obtained what is technically termed a square thread, as shewn in fig. 4. In the same manner, a third and a fourth cylinder are screwed, each being successively a degree smaller than the preceding. The small frame holding the cutter is now removed, and replaced with dies, a set of which is to be screwed with each of the above cylinders. When the dies are to be screwed, they are placed in the die-frame with one of the cylinders already made, and pressed against it by the screws G g, until they are fully screwed. After this, they are replaced with another cylinder, and another set of dies, which are likewise to be screwed. The same operation is performed with a third and a fourth set; (the first set of dies only, having a sharp thread, the other set hav- ing square threads,) after which they are to be tempered. The headstock is now removed to the left, to admit the cylinder of which the perfect screw is to be formed, and fastened at any required distance, the machine being constructed to cut a screw above three feet in length. The cylinder being placed i # i :- # Frc. 3. 7 4. | ſ W between the sharp dies, which are gently pressed by the screws G 9, is turned round by the handle, until the die-frame reaches the left hand of the cylinder; it is then turned in the contrary way, and worked in the same manner as when using the cut- ter. When a square-thread screw is to be made, the sharp dies must be removed after the indentation is sufficiently deep to admit the square dies, which are to be substituted for the former; when these have cut the screw to a considerable depth, a smaller set of square dies is taken in succession, until the screw is finished. w N. B. Figs. 7 and 8 represent a small stock made of steel, and hardened, for holding the cutter while sharpening. Figs. 9 and 10 represent an edge and side view of the cutter. Figs. 5 and 6 represent the dies. SCRIBE, a principal officer in the Jewish law, whose business it was to write and interpret scripture. SCRIBING, in Joinery, the joining two pieces of wood together, when the surfaces are irregular, so that the protu- berances in the one part shall suit with exactness the indenta- tions of the other. SCRIPTURE, WRITING, the revelation of God to man, as contained in the Bible. All profane scoffing at the holy scrip- ture, or exposing any part thereof to contempt or ridicule, is 1 Haw. 7. | |ICſ } - El- *- The same |- SCRIVENER, one who lends money out at interest. Also, one who transacts money matters between contracting parties. SCROFULA, a disease commonly called the king's evil. The name scrofula was derived from an opinion that swine were particularly subject to this affliction. SCROLL, in Heraldry, is the ornament placed under the escutcheon, containing a motto or short sentence, alluding sometimes to the bearings, or the bearer's name; sometimes expressing somewhat that is divine or heroic, and sometimes what may be deemed heroical. - SCRUPLE, a weight equal to the third part of a drachm, or to twenty grains. - . - SCRUTORE, or Scrutoire, a kind of cabinet, with a door or 'lid opening downward, for the conveniency of writing. SCUD, a name given by seamen to the low and thin clouds which are most swiftly wafted along by the wind in dull weather. SCUDDING, the movement by which a ship is carried pre- cipitately before a tempest, and is either performed with a sail extended on her foremast, or, if the storm is excessive, without any sail, which is then called, scudding under bare poles. In sloops and schooners, and other small vessels, the sail em- ployed for this purpose is called the square-sail. In large ships it is either the foresail at large, reefed, or with its goosewings extended, according to the degree of the tempest; or it is the fore-topsail close reefed, and lowered on the cap, which last is particularly used when the sea runs so high as to becalm the foresail occasionally, a circumstance which exposes the ship to the danger of broaching to. As a ship flies with amazing rapidity through the water whenever this expedient is put in practice, it is never attempted in a contrary wind, unless when her condition renders her incapable of sustaining the mutual efforts of the wind and waves any longer on her side, without being exposed to the most imminent danger. The hazards to which this operation subjects a vessel are, a pooping sea, the difficulty of steering to prevent broaching-to, and the want of sufficient sea-room. A sea striking the ship violently, may dash it inwards, by which she must inevitably founder ; in broach- ing-to suddenly, she is threatened with being immediately overset; and for want of sea-room, she is endangered by ship- wreck on a lee-shore. SCULL, among sailors, a kind of short oar, the loom of which is only equal in length to half the breadth of the boat, whereby two may be managed by one man, one on each side. To Scull, is to cause a boat to advance by a particular method of ma- naging a single oar over the boat's stern. SCULLER, a term denoting a boat rowed by one man with two short oars, or rather sculls; it is used in contradistinction to OARs, which signifies a boat rowed by two men with oars. SCULPONAE, among the Romans, a kind of shoes worn by slaves. They were hollow blocks of wood, like French sabots. SCULPTURE, is an art, in which, by means of taking away, or adding to matter, all sorts of figures are formed, either in clay or wax, wood, marble, or other stones, or metal. The art of sculpture, in its most extensive sense, comprehends not only carving in wood, stone, or marble, but also enchasing, engrav- ing in all its kinds, and casting in bronze, or lead, wax, and plaster of Paris, as well as modelling in clay, wax, or stucco: SCUM, a light excrement arising from liquors when briskly stirred; also called foam, froth, or spume. Scum is also used for the impurities which a liquor by boiling casts up to the surface, and likewise for those taken from metals in a state of fusion. These are also called tutty and scoria. - SCUMA, the scales of any metal, and particularly applied t the small flakes flying off from hot iron under the hammer. SCUPPERS, certain channels cut through the water-ways and sides of a ship at proper distances, and lined with sheet- lead, in order to carry the water off the deck into the sea. SCUPPER-HOSE, a leathern pipe or tube nailed round the outside of the scuppers of the lower decks, and which by hang- ing down prevents the water from entering when the ship in- . clines under a pressure of sail. Scupper-Nails, have very broad heads, so as to retain a great quantity of the hose under them. Scupper-Plugs, are used to stop the scuppers occasionally. SCURF, small exfoliations of the skin which occur after a slight inflammation, and when a new exterior of skin is forming under that which is thrown off. S F. A E A DICTIONARY OF MECHANICAL SCIENſ. E. S 925 SCURRA, an ancient name given to the jackdaw. SCURVY, a formidable and often fatal disease, arising from salt provisions, imperfect nutrition, and other causes. Seamen, during long voyages, are particularly subject to it; but it is also an endemic of the land. Some have thought that it has an affinity to the leprosy, the degree depending on climate, &c. SCUTAGE was anciently a tax imposed on such as held lands, &c. by knight's service, towards furnishing the king's alſ IIl W. - §§uTARIUs, among the Romans, a shield-maker; also it denotes a life-guard of the emperor, because his body was covered with armour. SCUTTLE, in Agriculture, a shallow basket used in barns and in stables for various purposes. The sizes are indefinite. Scuttle, a small hatchway, or hole, cut for some particular purpose through a ship's decks or sides, or through the cover- ings of her hatchways, and furnished with a lid which firmly encloses it when necessary. º SCUTTLING, the act of cutting large holes through the bottom, sides, or decks of a ship, for various occasions, parti- cularly when she is stranded or overset, and continues to float on the surface, in order to take out the whole or part of the cargo, provisions, stores, &c. To Scuttle a Ship, to sink her by making holes through her bottom. SCUTTLE-BUTT, or CAsk, is a cask having a square piece sawn out of its bilge, and lashed upon the deck. It is used to contain the fresh water for daily use, whence it is dipped out with a leaden can. - SCUTUM SOBIESKI, or Sobieski’s Shield, a constellation formed by Hevelius: the stars are seven ; but four of these are enumerated in the Aquila, in the Britannic catalogue. SCYBOLA, in Medicine, a name given to the contents of the bowels when hard, dry, and formed into small masses resem- bling the excrement of sheep. SCYPHUS, among the Romans, a very large drinking cup, which was sometimes called the cup of Hercules. SCYRA, a fine imposed on such as neglected to attend the Scy regemot courts, which all tenants were bound to do. SCYREGEMOT Court, a county court, anciently held twice a year, by the bishop of the diocese and the alderman or sheriff, in which both the ecclesiastical and temporal laws were given in charge to the county. SCYTHE, Sithe, or Sythe, an edge-tool used in mowing, being a crooked blade joined nearly at right angles to a long pole or handle. This instrument is well known, and universally valued. SEA, is a great collection of water; by sailors, however, this word is variously applied to a single wave, to the agitation produced by a multitude of waves in a tempest, or to their par- ticular progress or direction. Thus they say, we shipped a heavy sea—there is a great sea in the offing--the sea sets to the southward. Hence also a ship is said to head the sea when her course is opposed to the setting or direction of the surges. A long Sea, implies a uniform and steady motion of long and extensive waves. A short Sea, is when they run irregularly, broken, and interrupted, so as frequently to break over a vessel's bow, side, or quarter. SeA-Boat, a vessel that bears the sea firmly, without la- bouring heavily, or straining her masts, or rigging. Sea-Breeze, the current of air which blows during the day from the sea upon the shore in warm climates. Sea-Clothes, are jackets, trowsers, &c. Sea-Coast, the shore of any country, or that part which is washed by the sea. Sea-Legs, implies the capacity of walking on a ship's decks when she pitches or rolls about at sea. SeA Kale, the common name of a highly nutritious and pala- table vegetable, now much cultivated, and greatly esteemed. SeA-Mark, a point or conspicuous object distinguished at sea; they are of various kinds, as promontories, steeples, ruins, trees, &c. and are very beneficial by informing vessels of their situation on the coast. - SeA-Port, a haven near the sea, as distinguished from one which is situated up a river. SEA-Room, implies a sufficient distance from land, rocks, or shoals, wherein a ship may drive without danger of shipwreck. SeA-Salt, muriate of Soda., SeA-Weed, a sort of herb or tangles floating on the surface of the sea, or washed upon the spatcoast. 97-8. . . SEAL, a pumcheon, or piece of metal, or other matter, usually either round or oval, whereon are engraven the arms, device, &c. of some prince, state, community, magistrate, or private person, often with a legend or subscription, the impres- sion whereof in wax, serves to make acts, instruments, &c. authentic. Before the time of William the Conqueror, the makers of all deeds only subscribed their names, adding the sign of the cross, and a great number of witnesses; but that monarch and the nobility used seals with their arms on them, which example was afterwards followed by others. The colour of the wax where with this king's grants were sealed was usually green, to signify that the act continued fresh for ever, and of force. A seal is absolutely necessary in respect of deeds, because the sealing of them makes persons parties thereto, and without being sealed they are void in law. SEALER, an officer in chancery, appointed by the lord chancellor, or keeper of the great seal, to seal the writs and instruments there made in his presence. SEALING, in Architecture, the fixing a piece of wood or iron in a wall with plaister, mortar, cement, lead, and other solid binding, - SEAM, or SEME, of corn, is a measure of eight bushels. SEAM of Glass, the quantity of 120 pounds, or 24 stones, each five pounds weight. The seam of wood is a horse-load. SEAMAN, or SEAFARING-MAN, a person trained to the occu- pation of a mariner or sailor. The principal articles required in a common sailor are, that he should be able to steer, to Sound, and to manage the sails, by setting, reefing or furling them ; he is then called an able seaman. SEAMEN, in Law : by various statutes, sailors having served the king for a limited time, are free to use any trade or pro- fession, in any town of the kingdom. By 2 George II. c. 36, made perpetual by 2 George III. c. 31, no master of any ves- sel shall carry to sea any seaman, his own apprentice excepted, without first entering into an agreement with such seaman for his wages; such agreement to be made in writing, and to declare what wages such seaman is to receive during the whole of the voyage, or for such time as shall be therein agreed upon; and such agreement shall also express the voyage for which such seaman was shipped to perform the same, under a penalty of £10 for each mariner carried to sea without such agreement, to be forfeited by the master to the use of Greenwich Hospital. This agreement is to be signed by each mariner within three days after entering on board such ship, and is, when executed, binding on all parties. SEAMS, the intervals between the edges of the planks in the decks and sides of a ship, or the places where the planks join together; these are always filled with a quantity of oakum, and covered with pitch, to prevent the entrance of the water. Seam also implies that part where two edges of canvass are laid over each other and sewed down. SEARCH WARRANT, in Law, a kind of general warrant issued by justices of the peace, for searching all suspected places for stolen goods. Proper grounds, however, must be shewn for suspicion, before the warrant can be obtained. The name and place also must be specified, general warrants having long since been declared illegal. SEARCHER, an officer of the customs, whose business it is to search and examine all ships outward bound, to see whether they have any prohibited or uncustomed goods on board. SEASONINGS, in the West Indies, a kind of ague which Strangers endure on their coming to the islands. SEASONS, in Cosmography, contain portions of the year distinguished by the signs of the zodiae which the sun enters. Spring, summer, autumn, and winter, are their general denomi- nations. - SEAso Ns, Terrestrial Globe, for Illustrating the.—This ter- restrial globe, mounted on a new principle, the invention of Mr. Christie, a teacher of mathematics, is so constructed as familiarly to illustrate the earth's annual and diurnal motions, the diversity of the seasons, the sun’s apparent progress in the ecliptic, his increase and decrease of declination, and the com- parative lengths of days and nights at different times of the year on the same part of the earth, and at the same time of the year on different parts of the earth; as well as to solve all the prob- lems usually performed on a terrestrial globe. Scarcely a 11 C - 926. S E A S E A DICTIONARY, OF MECHANICAL SCIENCE. school, or a private family where there are children to instruct, is without a pair of globes; on the use of which different writers have proposed many problems, which, though simple in them- selves, have often become very difficult to learners, from the inadequacy of the common globes to illustrate them. Among these are the greater part, if not all those relating to the sun and earth jointly. . Many of the difficulties have probably arisen from the inconsistency of representing a place in motion while its horizon is at rest, which has hitherto been done by globe- makers. To remedy this, some writers have recommended the pole to be elevated as many degrees above the horizon as are equal to the sun's declination, instead of the latitude of the place. But this plan is also defective in some particulars; for, what the learner was taught to call the horizon, and what the author at the very time calls the horizon, ceases to be so when the pole is elevated for the sun's declination: besides, the change in the length of days and nights is, by this method, re- presented to arise from the alternate motion of the poles back- wards and forwards with respect to the Sun. To a terrestrial globe, the geographer owes his first correct notion of the earth's form ; of the relative sizes and situations of places on its sur- face; of its natural divisions into continents and islands, oceans and seas; and of its artificial divisions into empires, kingdoms, states, and provinces; and when mounted on this plan, it will greatly assist the teachers of astronomy in illustrating the mo- tion of a planet about the sun, The inventor was led to this discovery by having frequently found considerable difficulty in giving to his younger pupils correct notions of the earth's annual motion, and the conse- quent phenomena; nor does it appear that others have found the common globes sufficient for this purpose. Ferguson and Bonnycastle recommended a wire circle to be held or fixed in an oblique position, a candle to be placed in the centre, and a small globe suspended by a twisted thread to be carried round the wire circle by the hand. The untwisting of the thread is intended to represent the earth's diurnal, and the progress along the wire its annual motion. Keith sometimes employs the same method, but says, that it “does not so clearly shew the obliquity of the earth's axis to the plane of its orbit,” as one which he describes in his Treatise on the Use of the Globes. The apparatus contrived by Mr. Christie fully supplies these deficiencies; exhibiting a clear and intelligible view of the earth's passing through one side of the zodiac while the sun appears to pass through the opposite. ... It is neither so compli- cated nor so expensive as to prevent its being generally intro- duced, and it will greatly facilitate the pupil’s progress in what is called the use of the globes. Subjoined is a description of the engraving which will be found in the plate of Artificial Globes, Celestial and Terrestrial, fig. 8. - The chief novelties of this mounting are, a lamp covered by a hollow sphere of ground glass, representing the sun, round which a terrestrial globe moves, in a circle, whose plane makes with the horizon an angle of 233°; two parallel levers, support- ing the globe, and its counterpoise P; an horizon, h h, and a meridian, i m, both turning with it on its axis : a termina- tor, t r, distinguishing the parts of the earth enlightened from those in darkness; and a claw-feet pillar or stand, T, supporting the whole. Into the top of the stand, a piece of strong steel wire, w, is screwed, and its upper end is bent 23.4° from the perpendicular, corresponding with the inclination of the earth's axis to the plane of its orbit, . On the bent part of the wire is fitted a brass collar, (but invisible in the engraving,) from the opposite sides of which two points extend about an inch: these points move in centres fixed in the upper lever; and this motion permits the same side of the lever to continue upwards, while its ends are alternately elevated and depressed by the motion of the collar on the bent wire. The lower lever moves freely on the wire immediately under the bent part. The levers are con- nected at their ends by two pieces of brass, each piece having two square holes in it, to admit the ends of the levers. Into the opposite sides of each hole are screwed two steel points which move in centres, permitting the connecting pieces to continue perpendicular, while they are elevated and depressed with the ends of the levers. On the top of the piece connecting the long ends is screwed a brass tube, a b, containing the axis of a terrestrial globe, produced and sharpened to a conical point (at b), on which it rests and turns. On the lower end of the other connecting piece is screwed a leaden weight P, which balances the globe, and preserves the parallelism of its axis during its annual motion. On the top of the bent wire is fixed a circular board dc, on which are delineated the signs of the zodiac, days of the month, &c.; the board declines 233° from the level, representing a portion of the plane of the earth's or- bit; and a pointer, c, from the brass collar, moves with the levers along the circles of signs and months, shewing the sun's place or day of the month, corresponding with any position of the globe, or the position of the globe corresponding with any place of the sun or day of the month. A silk line extends round the circumference of this board and round a pulley on the axis of the globe, at b, to produce the diurnal motion ; the line is conveyed from the board to the axis through a brass tube b d, and after passing the pulley on the axis, it is carried round an- other pulley, (near b,) which being fixed to the end of the upper lever, preserves an equal tension on the line. Into the board immediately over the centre of motion of the levers, is screwed a stem supporting a lamp, with its ground glass cover. The remaining parts, viz. the hour circle, the meridian, the horizon, and the terminator, are more immediately connected with the globe. The hour circle, e o, is fitted on the axis below the globe, sufficiently stiff to preserve its adjustment, when set to the me- ridian of any place. The hour is indicated on it by a pointer, (at o,) attached to the brass tube, a. The meridian is a ring of brass attached to the poles, with its flat surface towards the globe; one semicircle of it is divided into degrees, and numbered from the equator towards the poles, for finding the latitudes of places, declination of the sun, &c. The horizon is a thin slip of brass, one end of which fits into a socket fixed on the other: it is attached to a wire which moves up or down with it in a groove near the edge of the meridian, representing at pleasure the ra- tional horizon of any place ; and it is divided into degrees and points of the compass, for finding the sun's azimuth, amplitude, &c.; it is necessary to separate the ends of the horizon when it is changed from N. to S. or from S. to N. latitude. Both meri- dian and horizon are turned with the globe on its axis, so that, when they are adjusted to the latitude and longitude of any place, they retain their adjustment till an alteration is required. In the pole of the horizon, a pointer, i, is fixed on the wire, shewing the zenith, to which a quadrant of altitude is occasion- ally attached. The terminator is sufficiently large to permit the globe with the other circle to turn within it; this circle is made a little concave, to reflect light on those parts which re- ceive but little of the direct light, and to mark more distinctly the difference between the light and dark hemispheres ; it is supported by two pivots, (one of which is seen at r,) fixed in its opposite sides, even with the equator: these pivots are fitted into and move in the ends of a strong semicircular wire, rn, which is supported behind the globe with a very strong piece of bent wire, n a, extending from the brass tube containing the axis ; and the lower part of the terminator is cut, to permit its passing the axis at the south pole, which it does when the sun's declination changes from north to south, or from south to north. From this lower part a circular wire, os, extends 90° upwards, on the top of which is fixed a pointer, s, representing a cen- tral ray from the sun : this pointer shews the sun's declination, azimuth, amplitude, altitude, and the place where he is vertical at a given time: from the top, a similar wire fy, extends 90° downwards behind the globe, where it is attached by a vertical | piece, g k, to the upper lever produced ; the lower end of the vertical wire is the same distance from the piece connecting the levers as its upper end is from the centre of the globe ; thus forming a kind of parallelogram, which in some positions of the globe takes the form of a rectangle, and in others that of a rhomboid. This contrivance preserves the face of the termi- nator constantly towards the lamp, and alternately exposes to its light the north and south poles during its annual motion. Illustrations.—To illustrate the earth's annual and diurnal motions, nothing more is necessary than to move the pointer slowly along the circles of months and signs, and the globe will be perceived to descend 234° below the level of the sun on one side, and to rise as many degrees above his level on the other, while the axis remains perpendicular to the horizon, or parallel to itself—the globe at the same time turns on its axis S E C s E 1 DICTIONARY OF MECHANICAL scIENCE. 927 from W. to E. representing the diurnal motion. During the annual motion, it will be perceived that, when the pointer is at the first degree of Aries on 21st March, the light extends from pole to pole; that all places continue equal portions of time in the light and dark hemispheres; that a straight line joining the centres of the sun and earth would pass through the equator, and consequently the sun has no declination ; and that the central ray is crossing the equator from south to north. From this time the earth will be seen gradually descending below the level of the sun, and the central ray gradually rising north of the equator till it reaches the tropic of Cancer, while the pointer, c, has passed through Aries, Taurus, Gemini, and reached the first of Cancer on the 21st of June ; when it will be perceived that a straight line join- ing the centres of the sun and earth would pass through the tropic of Cancer, and consequently the sun's declination is 234° north; that his light extends 2349 over the north pole, but does not reach the south by the same number of degrees; that the diurnal motion does not remove from his light any part of the north frigid; and that all places in north latitude will have their days longer than their nights, while all places in South latitude will have the reverse. From this period the earth will be seen gradually rising towards the level of the sun, and the central ray descending till it again reaches the equator, during which time the pointer, c, will be seen passing through Cancer, Leo, and Virgo, till it reaches the first of Libra on the 23d of September, when the observations which were made on the 21st of March will apply, except that the central ray will now be seen crossing the equator from north to south. From this time the earth will be seen gradually ascend- ing above the level of the sun, while the pointer, c, passes through Libra, Scorpio, and Sagittarius, till it reaches the first of Capricornus, when the central ray will have descended to the tropic of Capricornus on the 21st of December. It will now be perceived that a straight line joining the centres of the sun and earth, would pass through the tropic of Capricornus; that the sun’s declination is 233° south ; that his light extends 23#9 over the south pole, but does not reach the north by the same number ; that the earth's diurnal motion does not expose to his light any portion of the north frigid zone, nor remove from it any portion of the south frigid zone ; and that all places in the southern hemisphere have longer days than nights, while all places in the northern hemispheres have the reverse. From this time the earth will be seen gradually descending again, while the pointer, c, passes through Capricornus, Aquarius, and Pisces, till it again reaches Aries. The engraving, which is a perspective view, represents the position when the sun is in the 5th degree of Aquarius, on the 26th of February. SEBACIC ACID, an acid supposed to have been found in fat of a strong disgusting odour. - SEBATES, salts formed of the sebacic acids, and alkalies, earths, &c. SECALE, RYe, a genus of the digynia order, in the triandria class of plants, and in the natural method ranking under the fourth order, gramina. Rye is commonly sown on poor, dry, limestone or sandy soils, where wheat will not thrive. . By con- tinuing to sow it on such a soil for two or three years, it will at length ripen a month earlier than that which has been raised for years on strong cold ground. - - SECANT, in Geometry, is a line that cuts another, or divides it into two parts. SECEDERS, an appellation comprehending those who are dissenters from the established church of Scotland. This secession took place under John Glas in 1727. SECOND, in Geometry, Chronology, &c. the sixtieth part of a prime or minute, whether of a degree, or of an hour; it is denoted by two small accents, thms ("). SEconD, in Music, an interval of a conjoint degree. SECONDARY, in general, something that acts as second, or in subordination to, another. SeconDARY Rocks, are those in which numerous remains of Vegetables and animals occur. This division contains sand- stone, coal, stratified limestone, chalk, &c. Pebbles and water- worn fragments of rocks belonging to the former divisions, are Commonly found in many of the secondary rocks: hence it is inferred, by geologists, that they have been formedat a later period, and hence this class receives its name. SECRETARY, an officer who, by his master’s orders, writes letters, despatches, and other instruments, which he renders authentic by his signet. SECRETION, in the animal economy, the separation of some fluid mixed with the blood by means of the glands. SECTION, in Geometry, denotes a side or surface appear- ing, of a body or figure cut by another; or the place where lines, planes, &c. cut each other. SECTION of a Building, is the same with its profile; or a deli- neation of its heights and depths raised on a plane, as if the fabric was cut asunder to discover its inside. SECTOR, in Geometry, is a part of a circle, comprehended between two radii and the arch ; or it is a mixed triangle, form- ed by two radii and the arch of a circle. t SECUNDINES. After-birth. SEDAB, in Botany, a name given by the Arabian physicians to the wild or mountain rue, a plant common in Greece, Syria, and other places. SEDATIVE, in Medicine, nearly synonymous with anodyne; medicines, calculated to assuage pain. . SEDGE GRASSEs, a name given to various sorts of grasses of the poor carnation kind. They are hardy in their nature, prevail much in crude heavy land, and are rarely eaten by any cattle. SEDIMENT, the settlement or dregs of any thing; or that heavy portion of a fluid body which sinks to the bottom of a vessel. - SEDINA, a word used by some writers to express dragon’s blood. - * SEDITION, among Civilians, is used for a factious commo- tion of the people, or an assembly of a number of citizens without lawful authority, tending to disturb the peace and order of society. SEED, in Botany, the essence of the fruit of every vegetable. Linnaeus denominates it to be a deciduous part of the plant, containing the rudiments of the new vegetable, and fertilized by the sprinkling of the male dust. Plants are furnished with one seed, as the sea-pink; or two, as in umbelliferous plants; or three, as in the spurge ; or many, as in the ran unculus. &c. The shape, structure, and sides of seeds, are various. Linnaeus denominates seeds the eggs of plants ; and the fecundity of plants is often astonishing : there are 4000 seeds in a single sun-flower; more than 30,000 in a poppy ; and in a single tobacco plant 360,000 have been enumerated. The annual pro- duce of a single stalk of spleenwort has been estimated to be a million of seeds. Plants are disseminated in various methods: some are carried along by rivers and torrents many hundred miles from their native soil, and cast upon a very different climate, to which, however, by degrees they render themselves familiar. Some are formed by wings to be borne before the wind to distant places. Birds, squirrels, &c. swallow seeds, and void them whole and ſit for vegetation, and thus dissemi- nate them. There are others that disperse themselves by an elastic force, that resides either in the “calyx,” as in oats and the ferns; in their “pappus,” as in the centaurea crupina, or in their “capsule,” as in the geranium. . SEGGARS, in the manufacture of porcelain and pottery, are cases formed of coarse clay, capable of sustaining the required heat without fusion; in which different kinds of earthenware are baked. - SEGMENT of a SPHERE, is a part of a sphere terminated by a portion of its surface, and a plane which cuts it off, passing somewhere out of the centre; being more properly called the section of a sphere. * SEIGNORA GE, signifies the right or due belonging to a seigneur or lord ; but it is particularly used for a duty belong- ing to the prince for the coinage of money, called also coinage : which under our ancient kings was five shillings for every pound of gold brought in the mass to be coined, and a shilling for every pound weight of silver. At present the king claims no seignorage at all. SEINE, the name of a large fishing-net. SEISIN, in Law, signifies. possession. SEISE, SEAse, or Seaze, in the sea language, is to make fast or bind, particularly to fasten two ropes together with rope-yarn. SEIZING, the operation of faster*** any two ropes or dif- 928 S E Q S E N D1CTIONARY OF MECHANICAL SCIENCE. ferent parts of one rope together with a small line or cord. Seizing, implies also the cord which fastens them. e SEIZURE, in Commerce, an arrest of some merchandise, moveable or other matter, either in consequence of some law, or of some express order of the sovereign. SELENIUM. A new substance discovered by M. Berze- lius, which has the properties of a metal combined with those of sulphur to so great a degree, that it might be supposed to be a new species of sulphur. In its reguline state, it has a brilliant metallic lustre on the external surface, with a tinge of red; the fracture is vitreous like that of sulphur, but with a very brilliant lustré. of a gray colour. te SELENOGRAPHY, a branch of cosmography, which de- scribes the appearances of the moon, as geography does those of the earth. The invention of telescopes has much improved this branch of human knowledge. º SELF-LOVE, in Ethics, that principle which leads a person to desire, and pursue his own happiness. It is contradis- tinguished from benevolence. Few topics have been more fruitful in generating disputes, respecting its definition, appli- cation, and qualities, and few have been left more undecided. SELL, in Building, is of two kinds, viz. ground-sell, which denotes the lowest piece of timber in a timber building, and that on which the whole superstructure is raised; and the win- dow-sell, called also window-soil, the bottom piece in a win- dow frame. e SELTZER WATeR, the name of a mineral water of Germany, which rises near Seltzer, about four miles from Frankfort on the Mayne. It is much used in England, and mauy other countries, for its medicinal virtues. It has been found ser- viceable in scorbutic, cutaneous, and putrid disorders, and is strongly recommended in various other complaints. SELVAGE, a sort of hank or skein of rope-yarn, used to fasten round any rope as a shroud or stay, by which to hook a tackle, in order to set it up. SEMEN, a substance prepared by nature for the reproduc- tion and conservation of the species both in animals and plants. The peculiar liquid secreted in the testes of males, and destined for the impregnation of females, is so named. See SEED. SEMICIRCLE, in Geometry, half a circle, or that figure comprehended between the diameter of a circle and half the circumference. - gº SEMICOLON, in Grammar, one of the points or stops used to distinguish the several members of sentences from each her (; - te “ºpiurnal. Of any of those circles which the sus, appears to form each daily revolution, that portion which is above the horizon is called the diurnal arch, and that which is below the horizon is called the nocturnal arch, the halves of which are called the semi-diurnal and the semi-nocturnal arches SEMI-Metals, a term that expresses those metallic substances not possessing ductility and malleability, these properties being deemed characteristic of real metals. SEMINARY. See School. SeMINARY, in Gardening, is a place allotted for raising plants from seed, and keeping them till they are fit to be removed into the garden or nursery. te SEMITA LUMINOSA, a name given to a lucid track in the heavens, which, a little before the vernal equinox, or after the autumnal, may be seen about six in the evening, extending from the western edge of the horizon up towards the Pleiades. This stream of light bears some resemblance to the tail of a comet. SENA, or SENNA, or the Egyptian Cassia, in the Materia Me- dica, a purgative leaf much used in draughts, and compositions of that description. It is a native of Egypt; that of the best quality is said to grow in the valley of Basabras, or of Nubia. Senna of an inferior kind grows in the Levant, and abont Florence. Its operation is not violent, and it enters into the compound of various medicines. & SENATE, an assembly or council of the principal inhabitants of a state, who have a share in the government. Senates are differently formed according to the political constitutions of various countries. SENATOR, a member of a senate. SENDING, a naval term, expressing the act of a ship pitch- ing precipitately into the hollow or interval between two waves, SENEKA, or RATTLESNAKE Root. This plant is a native of Virginia, Pennsylvania, and Maryland, and is now cultivated in some of our gardeus. The root is perennial, the thickness about that of a man's little finger, and its length about four or fiye inches, being variously contorted and twisted. It has only of late been brought into use among us; but it is thought worth; of great regard. A knowledge of its virtues was first taught the Europeans by the Senegal Indians, who esteemed it a sove- reign remedy against the bite of the rattlesnake; in which cha- racter it has been found efficacious. - * SENNIT, a kind of flat braided cordage used for various purposes, and formed by plaiting five or seven rope-yarns together. t - SENSATION, in Physiology, is a general term denoting the effect produced in the mind by the impression of external bodies on our organs of sense, namely, seeing, hearing, feeling, tasting, and smelling. SENSE, sometimes means the organs of sensation, and at other times it is used for understanding, judgment, and con- science. SENSIBILITY, the power of receiving an impression, and transmitting it to the brain, so as to occasion an acute sensa- tion or feeling. - SENSITIVE FLUID, a fluid which is supposed to preserve animals from corruption. It is presumed, to pass through the nervous tubes, and to convey the impression to the sensorium. SENSITIVE Plant. See MiMos A. SENSORIUM, the part of man which feels and perceives, the common centre to which sensations are conveyed, and from which volitions emanate. SENTENCE, in Grammar, a period or set of words compre- hending some perfect sense or sentiment of the mind. SENTENCE, in Law, a judgment passed in court by the judge upon some process either civil or criminal. - SENTINEL, in War, a private soldier placed in some post to watch the motions of an enemy, to prevent surprises, and to stop such as would pass without orders, or shewing who they are. SEPIA, the cuttle-fish, a genus belonging to the order of yermes mollusca. There are eight brachia interspersed on the interior side with little round serrated cups, by the contraction of which the animal lays fast hold of any thing. Besides these eight arms, it has two tentacula longer than the arms, and frequently pedunculated. The mouth is situated in the centre of the arms, and is horned and hooked. The eyes are below the tentacula, towards the body of the animal. The body is fleshy, and received into a sheath as far as the breast. Their food are tunnies, sprats, lobsters, and other shell-fish. With their arms and trunks they fasten themselves to resist the mo- tion of the waves. Their beak is like that of a parrot. The females are distinguished by two paps. This animal was es- teemed a delicacy among the ancients; and is eaten at present by the Italians. The bony scale on the back is that which is sold in the shops, and which, when reduced to fine powder, is reckoned excellent for the teeth, as well for keeping them white as for preserving them. It is also used as pounce. These ani- mals have the power of squirting out a black fluid resembling ink, which is said to be an ingredient used in the composition of Indian ink. - SEPS, in Zöology, the name of a peculiar kind of lizard, between that genus and the snakes. It appears as a serpent with feet. Its bite is said to be followed by instant putrefac- tion and speedy death. SEPTEMBER, the ninth month of the year, reckoned from January, and the seventh from March, whence its name, viz. Septimus, seventh. SEPTICS, among Physicians,.a name given to all such sub- stances as promote putrefaction. SEPTUAGINT, the name given to a Greek version of the books of the Old Testament, from its being supposed to be performed by seventy-two Jews, who are usually called the seventy interpreters, because seventy is a round number. SEPULCHRE, a tomb or place appropriated for the inter- ment of the dead. SEQUESTRATION, is the separating or setting aside of a thing in controversy, from the possession of both those who S E. R. S E S DICTIONARY OF MECHANICAL SCIENCE. 929 contend for it. A sequestration is also a kind of execution for debt, especially in the case of a beneficed clerk, of the profits of the benefice to be paid over to him that had the judgment, till the debt is satisfied. - SERAGLIO, denotes the palace of a prince or lord. At Constantinople they say the seraglio of the ambassador of England, France, &c. In a more eminent sense, the Turks apply the term to the palace of the grand seignior, where he keeps his court, where his womeri are kept, and where the youth are trained up for the chief posts in the empire. The whole building is in a triangular form, about three Italian miles in circuit. That part of the seraglio in which the women reside is called the Harem. - SERAPH, or SerAPHIM, supposed to be an angel of the first or highest rank, and to be more inflamed with divine love than others, and hence the name, which signifies to burn, to inflame. SERENADE, an evening concert given by a lover under the window of a room in which his mistress resides. . SERGE, in Commerce, a woollen stuff manufactured in a loom, of which there are various kinds, denominated either from their different qualities, or from the places where they are wrought; the most considerable of which is the London serge, which is highly valued abroad. - • ** SERIES, in general, denotes a continued succession of things in the same order, and having the same relation or con- nexion with each other. - - - Series, Infinite, is a series consisting of an infinite number of terms, that is, to the end of which it is impossible to come ; so that let the series be carried on to any assignable length, or number of terms, it can be carried yet farther, without end or limitation. . . . - - SERICH, the name of a seed used in the food of the Egyp- tian Coptics. - pounded and put into oil. In this they dip their bread, which is always new, being baked in small cakes, as often as they eat. Raw onions are added to this repast. SERGEANT, or Serjeant, in War, is an inferior officer in a company of foot, or troop of dragoons, armed with a halberd, and appointed to see discipline observed, to teach the soldiers the exercise of their arms, and to order, straighten, and form ranks, files, &c. Serje ANT at Law, is the highest degree taken in that profes- sion, as that of a doctor is in the civil law. To these serjeants, as men of great learning and experience, one court is set apart for them to plead in by themselves, which is the court of com- mon pleas, where the common law of England is most strictly observed ; yet, though they have this court to themselves, they are not restrained from pleading in any other courts. The judges cannot be elevated to that dignity till they have taken the degree of serjeant at law. They are called brothers by the judges, who hear them next to the king’s counsel ; but a king's serjeant has precedence of all but the attorney and soli- citor general. These are made by the king's mandate, or writ. SERJEANTY, signifies in law a service that cannot be due from a tenant to any lord, but to the king only; and it is either grand serjeanty, or petit Serjeanty. SERMON, a discourse delivered in public, for the purpose of religious instruction and moral improvement. The present mode of delivering sermons may be traced to the book of Nehe- miah, chap. viii. 4. - SERMONIUM, a kind of interlude, which, in ancient times, the inferior clergy, assisted by boys, used to act in the body of the church, on certain festivals. The representative selections were made according to the occasion, SERPENT, in Music, a wind instrument of the bassoon kind, deriving its name from its serpentine figure. SerPENT, in Mythology, was a symbol of the sun. He is represented as biting his tail, having his body in a circle, indi- cating the apparent motion of that luminary round the globe. The serpent biting his tail, is likewise considered as an emblem of etermity. The serpent was, from time immemorial, an object of religious veneration and worship in Egypt; and in subse- quent ages, was a symbol of medicine, and of Apollo and Esculapius, the gods which presided over it. SERPENTES, in Natural History, an order of the Amphibia, ºntºs Seven genera; viz. Achrochordus, Amphisbaena, An- 7-8. It is produced by an herb called scinsim, and is guis, Boa, Coecilia, Coluber, Crotalus. Serpents are distinguish- ed as footless amphibia—their eggs are connected in a chain— penis frequently double—they breathe through the mouth—are cast naked upon the earth, without limbs, exposed to every injury, but frequently armed with a poison the most deadly and horrible : this is contained in tubular fangs resembling teeth, placed without the upper jaw, protruded or retracted at plea- sure, and surrounded with a glandular vesicle by which this fatal fluid is secreted; but lest this tribe should too much en- croach upon the limits of other animals, the benevolent Author of nature has armed about a fifth part only in this dreadful man- ner, and has ordained that all should cast their skins, in order to inspire a necessary suspicion of the whole. The jaws are dilatable and not articulate, and the oesophagus so lax that they can swallow without any mastification an animal twice or thrice as large as the neck; the colour is variable, and changes accord- ing to the season, age, or mode of living, and frequently vanish- es, or turns to another, in the dead body; tongue filiform, bifid; skin reticulate. The distinction between the poisonous and innoxious serpents, is only to be known by an accurate exa- mination of their teeth; those which are poisonous being always tubular, and calculated for the injection of the poisonous fluid, | from a peculiar reservoir communicating with the fang on each side the head. Serpents in cold and temperate climates con- ceal themselves during the winter in cavities beneath the sur- face of the ground, or in any other convenient places of retire- ment, where they become nearly or wholly in a state of torpi- dity. Some serpents are viviparous, as the rattlesnake; the viper, &c. : while the innoxious species are oviparous, depo- siting, as we have observed, their eggs in a kind of chain in any warm and close situation, where they are afterwards hatched. The broad undivided laminae on the bellies of serpents are termed scuta, and the small or divided ones beneath the tail are called subcaudal scales, and from these different kinds of laminae, the Linnaean genera are characterized. SERPENTINE. This beautiful stone takes its name from its variegated colours being supposed to resemble a serpent’s skin. It consists of silica 32, magnesia 37-24, alumina 0-5, lime 10-6, iron 0.66, volatile matter and carbonic acid 1416. The colours are most generally various shades of light and dark green, which are intermixed in spots and clouds: some vari- eties are red. When fresh broken, it has some degree of lustre, and a slight unctuous feel. It is harder than lime-stone, but yields to the point of a knife, and will receive a very high polish. When serpentine is found intermixed with patches of crystalline white marble, it constitutes a stone denominated verde-antique, which is highly valued for ornamental sculpture. Beautiful varieties of green serpentine occur in the isle of An- glesea, about six miles from the Paris copper mine. SERVANT, a person who, in consideration of some stipu- lated remuneration, owes and pays limited obedience to the com- mands of another in the quality of master. An agreement, when the time is not specified, the law determines to be for one year; but by mutual agreement, a separation may take place at any intermediate stage. Servants are of various kinds and degrees, and several laws regulate their obedience, and the treatment they are entitled to expect. SERVICE, in Law, is a duty which a tenant, on account of his fee, formerly owed to his lord. - SERVING, is the winding any thing round a rope to prevent it from being rubbed : the materials used for this purpose, which are called service, are generally spun-yarn, small lines, sennit, or ropes, varying in thickness, according to the dimen- sions of the rope to be served ; sometimes leather, old canvass, &c. are used... ... SERVITOR, in the university of Oxford, a scholar or stu- dent who attends and waits on another for his keep there. - SER vitoRs of Bills, such messengers of the marshal of the king's bench as are employed to summon men to that court. They are now commonly called tipstaves: SERUM, a thin transparent liquor, which makes a consider- able part in the mass of blood. SESAMUM, Oily Grain, a genus of plants belonging to the class of didynamia, and to the order of angiospermia, and in the natural system ranking under the 20th order, Iuridae. SESSION, in Law, denotes a sitting of justices in court upon 1 i D - 930 S H A S F. X. DICTIONARY OF MECHANICA L SCI ENCE. their commission: as the session of oyer and terminer, &c. ‘See QUARTER, SEssions. - - - SET-OFF, in Law, is when the defendant acknowledges the justice of the plaintiff's demand on the one hand, but on the other sets up a demand of his own, to counterbalance that of the plaintiff, either in the whole or in part; as if the plaintiff sue for 10l. due on a note of hand, the defendant may set of 91. due to himself for merchandise sold to the plaintiff, or for any other -demand, the amount of which is ascertained in damages. The action in which a set-off is allowable upon the statutes 2 and 3 George II. c. 22 and 24, are debt, covenant, and assumpsit, for the non-payment of money; and the demand intended to be set up must be such as might be made the subject of one or other of these actions. A set-off, therefore, is never allowed in actions upon the case, trespass, replevin, &c. nor of a penalty in debt on bond conditioned for the performance of covenants, &c.; nor of general damages in covenant or assumpsit; but where a bond is conditioned for the payment of an annuity, a set-off may be allowed. A debt barred by the statute of limitations cannot be set off; and if it be pleaded in bar to the action, the plaintiff may reply the statute of limitations; or if given in evi- dence, on a notice of set-off, which is one mode of setting up this sort of counter-demand, it may be objected to at the trial. SETS, in Agriculture and Gardening, a term applied to the cuttings or planted parts of potatoes, hops, liquorice, laven- der, &c. - SETTEE, a vessel of two masts, equipped with triangular sails, commonly called lateen sails; these vessels are peculiar to the Mediterranean, and are generally navigated by Italians, Greeks, or Mahometans. - SETTING, in the sea language. To set the land or the sun by the compass, is to observe how the land bears on any point of the compass, or on what point of the compass the sun is. Also, when two ships sail within sight of one another, to mark on what point the chased bears, is termed setting the chase by the compass. - - SETTI.EMENT, Act of, a name given to a statute 12 and 13 W. III. cap. 2, by which the crown was limited to his pre- sent majesty’s illustrious house, and by which some new pro- visions were added in favour of the subject, securing his liberty, and the rights of conscience. SEWED, the situation of a ship which rests upon the ground; and while the depth of water around her is not sufficient to float her, she is said to be sewed by as much as is the differ- ence between the surface of the water and the ship’s floating- mark, or water-line. SEWER, a passage or gutter made to carry water into the sea or a river, whereby to preserve the land, &c. from inun- dations, and other annoyances. The business of the commis- sioners of sewers, or their office in particular, is to repair sea- banks and walls, survey rivers, public streams, ditches, &c. and to make orders for that purpose, - - SEX, something in the body which distinguishes male from female, and is common to both plants and animals. SEXANGLE, in Geometry, a figure having six sides, and consequently six angles. SEXAGESIMALS, or Sex AG Esi MAL FRActions, fractions whose denominators proceed in a sexagecuple ratio ; that is, a prime, or the first minute =;; nomy, and they are still retained in many cases. - SEXTANT, in Mathematics, denotes the sixth part of a circle, or an arch comprehending sixty degrees. SEXTANT, an instrument for taking altitudes and other angular distances; it is constructed on a principle similar to HADLEY's QUADRANT, but the arc, containing a sixth part of a circle, may be taken to 120°. Sextants are generally fitted with apparatus for ascertaining the angular distances, &c. in lunar observations. SEXTON, a church-officer whose business is to take care of the vessels, vestments, &c. belonging to the church, and to at- tend the minister, churchwardens, &c. at church. SEXUAL SYSTEM, in Botany, denotes that system which is founded on a discovery, that in vegetables, as well as in ani- mals, there is a distinction of sexes. This fact seems to have been partially received so early as the days of Herodotus; but R a second =sºn; a third =grºup. Anciently there was no other than sexagesimals used in astro- it afterwards sunk into disrepute, and was nearly forgotten, until the diligence of modern observations placed its certainty beyond all reasonable doubt. SHACK, an ancient feudal custom, which secures to the lord of the manor a right of pasturage in the lands of his tenants In Norfolk and Suſlolk the lords of the manors still have shack during the six winter months. Shack is also applied to grain that is wasted in the fields during harvest. - SHACKLES, semicircular pieces of iron, sliding upon a round bar, in which the legs of prisoners are occasionally con- fined to the deck. SHADOW, in Optics, a privation or diminution of light, by the interposition of an opake body ; or it is a space where the light is either altogether obstructed, or greatly weakened by the interposition of some opake body between it and the lumi- nary. . SHAFT, in Building, is the body of a column, and is so called from its straightness; it also has frequently the name of fust. The same term is likewise used for the spire of a steeple, and for the shank or tunnel of a chimney. SHAft, in Mining, is a hollow passage sunk, in general, per- pendicularly into the earth, to reach the ore. Shafts of this description are of various depths; some in Cornwall exceed two hundred fathoms. +. SHAft, in Agriculture, is the handle of a tool or implement, such as a spade, fork, shovel, &c. In carts and waggons shafts are the parts or poles between which the hinder horses draw. SHAGGE, or SHAG, in Ornithology, a water-fowl of the cormorant kind, frequently found on the English shores, parti- cularly on the nerthern parts. SHAGREEN, or CHAG ReeN, in Commerce, a kind of grained leather, prepared, as is supposed, of the skin of a species of squalus, or hound-fish, called the shagree, or shagrain, and much used in covering cases, books, &c. • SHAKES, and SHAky, terms frequently used by shipwrights and carpenters to denote the cracks or rents in any picce of timber, occasioned by the sum or weather. - SHALE, in Natural History, a variety of schistose clay. The acid emitted from shale during its calcination, uniting itself to the argillaceous earth of the shale, forms alum. About a hundred and twenty tons of calcined shale will make one ton of alum. The shale after being calcined is steeped in water, by which means the alum, which is formed during the calcina- tion of the shale, is dissolved. This dissolved alum under- goes various operations before it is prepared for the shops. This kind of shale forms large strata in Derbyshire, and fre- quently above the coal, in most coal counties throughout the kingdom. - t * * SHALLOP, a small light vessel, with two masts and Jug sails. Being good sailers, they were formerly much used by smugglers, and are now generally employed as tenders upon ships of war. - SHAllop, a sort of large boat with two masts, and usually rigged like a schooner. SHAMBLE, in Mining, a sort of niche or landing place, left at certain distances for raising ore or rubbish with shovels, when the depth is too great for one cast to lift it to the surface. Shambles are sometimes formed of boards, and at other times of benches cut in the ground. - SHAMBLes, in Marketing, are places where butchers expose their meat for sale in public. SHAMMY, or CHAMois LeATHER, a kind of leather, dressed either in oil or tanned ; and much esteemed for its softness, pliancy, and being capable of bearing soap without hurt. The true shammy is prepared of the skin of the chamois-goat. See CAPRA. The true chamois leather is counterfeited with com- mon goat, kid, and even sheep skin; the practice of which makes a particular profession, called by the French, chamoisure. The last is the least esteemed. “. . * * - SHANK, among Sailors, implies the oeam or shaft of an anchor. Shank-Painter, a short rope and chain which sustains the shanks and flukes of an anchor against the ship's side, as the stopper fastens the ring and stock to the cat-head. SHANSCRIT, or SANscRit, is the original language of the Hindoos, and is that in which their shaster, or holy book, i. written. g - - - - S H E 's H I 1) ICTIONARY OF MECHANICAL SCIENCE $931 SHARE, in, Agriculture, that part of a plough which enters and breaks the ground. - SHARK, in Ichthyology, a large voracious fish. Of this fish there are several species, as the blue, the basking, and the hammer-headed shark. They chiefly reside in the seas of warm climates, but occasionally visit colder regions. Some have been known to weigh four thousand pounds, and men have been found whole in them when opened. SHARK See SQUALUs. SHARP, in Music, a character, the power of which is to raise the note before which it is placed half atone higher than it would be without such a preposition. - SHARP-Bottom, is synonymous with a sharp floor, and is used in contradistinction to a flat floor. SHASTER, or SHAstraM, a sacred book containing the reli- gion of the Banians; it consists of three tracts: the first of which contains their moral law ; the second, the ceremonial; and the third delivers the peculiar observances for each tribe of Indians. - SHAWL, an article of female dress much prized in the East, and now commonly worn in Europe. Their prices vary, from one to 200 guineas, according to the fineness of their texture and materials, and the elegance with which they are finished. SHEAF, a small bundle of corn in the ear, bound up in the field, for the accommodation of carriage and thrashing. SHEARING, in Agriculture, the reaping of grain. Shear- ing also signifies the act of taking off the fleece from the sheep. SHEARWATER, in Ornithology, a bird well known in the Orkney isles, and in several other places. The young birds are caught in abundance in August, and, salted in barrels, are preserved for winter provisions. SHEATHING, in Naval Architecture, a sort of covering mailed all over the outside of a ship's bottom, to protect the planks from the pernicious effects of worms. This sheathing, in former years, consisted of thin boards, but sheets of copper having been found far preferable, these have of late been almost universally adopted, especially in long voyages. Robert Mushet, of the Royal Mint. pounds of copper. Another patent was taken out by Mr. Christopher Pope, of Bristol, for an invention which discarded copper altogether, and substituted plates composed of tin and zinc, or of tin, zinc, and lead united. These combinations, however, not fully answering general expectation, the lords of . the Admiralty consulted Sir Humphrey Davy on the subject. This scientific gentleman, after a number of experiments, re- commended the fixing of small masses or wires of tin, or of some other readily oxidable metal, in contact with the copper, by which he expected that the copper would be rendered so negatively electrical, that the sea water would act but slightly on it. In reducing theory to practice, his anticipations have not, however, been realized according to his wishes; and it is probable that copper sheathing must remain, as heretofore, until some more beneficial method shall appear, that has not yet been discovered. SHEAVE, a cilindrical wheel of hard wood, fixed by a pin in a block, to form the pulley. SPHECHINAH, in Jewish history, the name of that miracu- lous light, or visible glory, which was a symbol of the divine presence. SHED, in rural economy, a slight temporary building, to shelter cattle, or implements of husbandry, from the weather. SHEEP, in Agriculture, a well-known and valuable animal, of which the breeds and varieties are numerous. SHEEPSHANK, a sea term, implying a kind of knot made on a, rope to shorten it, and is particularly used on runners or ties, to prevent the tackle from coming block and block. By this contrivance, the body to which the tackle is applied may be hoisted much higher, or removed much further in a shorter time. Thus, if any weighty body is to be hoisted into a ship, and it be found that the blocks of the tackle meet before the The corrosion, however, arising from the action of the salt water, being more rapid than was expected, several experiments have been made to counteract its influence. For the improvement of copper sheathing by an alloy, a patent was taken out by Mr. His alloy consisted of two ounces of zinc, or four ounces of antimony, or eight ounces of arsenic, or two ounces of grain-tin, being added to one hundred object reach the top of the side, it will be necessary to lower it again, or hang it by some other method, till the runner of the tackle is sheepshanked. by which the blocks will again be sepa- rated to a competent distance. - SHEER, the longitudinal curve of a ship's decks or sides. Sheer is also the position in which a ship is sometimes kept when at single anchor, in order to keep her clear of it; hence, To break Sheer, is to deviate from that position, and thereby risk the fouling of the anchor. SHEERING, or SHEARING, in Woollen Manufacture, is the cutting off with large shears the too long nap, in order to make the cloth more smooth and even. SHEERING, the act of deviating or straying from the line of the course, so as to form a crooked and irregular path through the water, and may be occasioned by the ship's being difficult to steer, but it more frequently arises from the negligence or in- capacity of the helmsman. To Sheer up alongside, to approach a ship in a parallel direction. To Sheer off, to remove to a greater distance. & SHEERS, a nautical term, the name of an engine used to hoist in or get out the lower masts of a ship, and are either placed on the side of a quay or wharf, or are fixed on board of an old ship cut down; or, lastly, they are composed of two masts or large spars lashed together, and erected in the vessel wherein the mast is to be planted or displaced, the lower ends of the props resting on the opposite sides of the deck, and the upper parts being fastened together across, from which a tackle depends; this sort of sheers is secured by stays extending to the stem and stern of the vessel. . SHEET, a rope fastened to one or both the lower corners of a sail, to extend and retain it in a particular situation. When a ship sails with a side wind, the lower corners of the main and fore sails are fastened by a tack and a sheet, the former being to windward, and the latter to leeward; the tack is, however, only disused with a stern wind, whereas the sail is never spread without the assistance of one or both of the sheets; the stay- sails and studding-sails have only one tack and one sheet each; the staysail tacks are fastened forward and the sheets drawn aft, but the studding-sail tacks draw the outer corner of the sail to the extremity of the boom, while the sheet is employed to extend the inner corner: hence, To Sheet home, is to haul home a sheet, or to extend the sail till the clue is close to the sheet- block. SHEKEL, in Jewish Antiquity, an ancient coin, worth 2s. 3+d. Sterling. - SHELF, among Miners, the same with what they otherwise call fast ground, or fast country; being that part of the internal structure of the earth, which they find lying even and in an orderly manner. SHELL, in Artillery. See the article BoMB, &c. Shell of a Block, the outer frame, or case, wherein the sheave or wheel is contained, and traverses about its axis. . - Shells. Marine shells may be divided, as Mr. Hatchet ob- serves, into two kinds: those that have a porcelainous aspect with an enamelled surface, and when broken are often in a slight degree of a fibrous texture ; and those that have gene- rally, if not always, a strong epidermis, under which is the shell, principally or entirely composed of the substance called nacre, or mother-of-pearl. The porcelainous shells appear to consist of carbonate of lime, cemented by a very small portion of ani- mal gluten. This animal gluten is more abundant in some, how- ever, as in the patallae. The mother-of-pearl shells are composed of the same substance. They differ, however, in their struc- ture, which is lamellar, the gluten, forming their membranes, regularly alternating with strata of carbonate of lime. In these two the gluten is much more abundant. - SHEPHERD, one who has the care and management of sheep. SHERIFF. As keeper of the king's peace, the sheriff is the first man in the county, and superior in rank to any nobleman thereia, during his office. He may apprehend and commit to prison all persons who break the peace, or attempt to break it, and may bind any one in a recognizance to keep the king's 68 CE, SHIELD, an ancient weapon of defence, in the form of a light buckler, borne on the arm, to turn off lances, darts, &c. 932 S H I S H I DICTIONARY OF MECHANICAL SCIENCE, f SHIFTED, the state of a ship's ballast or cargo when it is shaken from one side to the other, either by the violence of her rolling, or by her too great inclination to one side under a great pressure of sail; this accident, however, rarely happens, unless the cargo is stowed in bulk, as corn, salt, &c. SHIFTER, a person appointed to assist the ship's cook in washing, steeping, and shifting the salt provisions. SHILLER Stone, a mineral nearly allied to serpentine. SHILLING, an English silver coin, equal to twelve pence, or the twentieth part of a pound. SHIM, in Agriculture, a tool used in breaking down and reducing the more stiff and heavy sorts of land, as well as cut- ting up and clearing them from weeds. SHINGLE, in Agriculture, the thinnings of fir and other timber trees, which are much used in making fences, &c., Shi NG Le, Rubbish, found on the sea shore, and used for bal- lasting ships, protecting embankments, and preventing the encroachments of the sea. SHING les, in Building, small pieces of wood, chiefly-oak, used for covering roofs, where other materials are scarce, and something light is required. SHIP, a general name given to all vessels navigated on the ocean; in the sea language, however, it is more particularly applied to a vessel furnished with three masts, each of which is composed of a lower-mast, a top-mast, and top-gallant-mast, with the yards and other machinery thereto belonging. A Ship cut down, implies one which has had a deck cut off from her, whereby a three-decker is converted into a two-decker, and a two-decker becomes a frigate. A Ship raised upon, is one whose dead works have been heightened by additional timbers. Hospital SHIP, a vessel fitted up to attend a fleet of men- of-war, and receive their sick or wounded, for which purpose her decks are high, and her ports large. The gun-deck is en- tirely appropriated for the reception of the sick, and is flush without cabins or bulk-heads, except one of deal or canvass, for separating those in malignant distempers. Two pair of checquered linen sheets are allowed to each bed, and scuttles cut in the sides for inlets of air. The sick are visited by a physician, and constantly attended by a surgeon, a proportional number of mates, assistants, baker, and washerwomen. Her cables ought also to run upon the upper deck to the end, that the beds or cradles may be more commodiously placed between decks, and admit a free passage of the air, to disperse that which is offensive or corrupted, Merchant SHIP, a vessel employed in commerce to carry commodities of various sorts from one port to another, the largest of which are those used in trading to the East Indies. Prison Ship, a vessel fitted up to receive prisoners in a port. Private Ship of War. See PRIVATEER. Receiving Ship, a ship stationed at any place to receive volunteers and impressed men, and train them to their duty in readiness for any ship of war which may want hands. Slave Ship, a vessel employed in carrying negro slaves from the coast of Africa to the West Indies, &c. whence she returns to Europe with a cargo of rum, sugar, coffee, cotton, &c. Slop Ship, a vessel appointed as a depôt of clothes for the seamen. Store Ship, a vessel employed to carry artillery and stores for the use of a fleet, fortress, or garrison. Troop Ship, is one appointed to carry troops, and is frequently termed a transport. - SHIP Building, may be defined, the manner of constructing ships, or the work itself, as distinguished from naval architec- ture, which may be considered as the theory or art of delineating ships on a plane. - HIPWRECKED SEAMEN, Plan for the Preservation of, by Captain G. W. Manby.—Instructions. After the means of com- munication have been effected between a stranded vessel and the shore, by a rope attached to a shot projected from a mortar, it is often found a matter of great difficulty to make the per- sons on board know how they are to act, and many lives have been lost through this cause alone. In order to remedy this evil, and to render this system of relief mutually and imme- diately understood, the following instructions are submitted :- Directions to Persons on board Vessels stranded on a Lee- Shore.—It is your duty, as well, no doubt, as your inclination, to use every honourable and manly endeavour to save the vessel these have failed, before it is a justifiable resource to run the ship on shore, for the preservation of your own lives. On the determination being made to run for the beach, every exertion should be made to keep your vessel off the shore till high water, and then, if canvass is or can be set, steer the vessel stem on with as much force as possible, making signals of distress to attract the notice of the people on shore, who will collect at the point most favourable for the purpose, and prepare to assist you ; endeavour to run for the spot where they are collected. Shipmasters, on these occasions, must enforce their authority more than ever, and seamen must be more than usually obedi- ent, as the safety of all on board will frequently depend on this. * 3.32°S. §ºses ńftº: gº % º &# - º out any choice of time or place, the following directions will equally apply, and Inust be minutely observed and practised:— Collect, in some safe part of the vessel, ready to apply as occa- sion may require, all your small lines and ropes, buoys, pieces of cork, or small kegs, (such as seamen keep spirits in,) Snatch, tail, and other blocks, with a warp or hawser clear, axes, knives, &c.; all these may be of great use. Attend to the people on shore, and observe if they have a boat, or are getting one to the spot, as their first object would be to launch it to you, and to throw a line on board you, to haul her off with ; in that case they will make signal No. 1. The signals, illustrated by representations and their distinct meanings, will be hereafter described. On receiving the line, you will secure the end to such part of the vessel as may best draw the boat into a safe lee. If the people on shore, after you have received the line, make signal No. 2, you will bend the warp or hawser to the line, and they will draw it on shore, fearing to trust the boat to the small line. When the bend is made, and you are ready, make your signal No. 1, (which will be hereafter described, ex- pressing yes.) If, when you have got the line, the people on shore find you have not a warp ready, and wish you to haul on board by it a stouter rope to haul the boat off with, they will make signal No. 3, to haul away, for you to receive a stout rope; secure it as before directed, and make your signal No. 1, which is also to denote you are ready, or their direction is com- plied with. s Remark.—A boat, when it can be applied, is the promptest method of bringing a crew on shore. Upwards of twenty crews have been saved by them. * If, when you have received the line, and observe there is no boat at hand, and the signal on shore (No. 3) is made, you will haul in, and receive by it the end of a stout rope, and a tail- block rove with a small line, both ends of which are kept on shore; make the end of the stout rope and the tail of the block well fast round your mast, higher or lower, as circumstances require, and the tail-block close below the large rope. On your making signal No. 1, denoting to have complied with the direction of having carefully secured the stout rope and tail- block, the people on shore will haul taut the stout rope, and place on it a snatch-block, (with a sling hanging to it large enough to hold a man;) and making the ends of the small line fast to the lower part of the snatch-block, they will work it to the ship, when, on a man getting into the sling, he will, by pull- ing down the slide or button, secure himself in, and safely - lashing himself by the waist to the upper part of the sling, prevent the possibility of falling out; and on seeing the clasp” Tº This remark is necessary, from the omission of the clasp being here and cargo committed to your care, and to satisfy yourself that represented, that should cross the mouth of the block. 'S H I S H. f. DICTIONARY OF MECHANICAL SCIENCE. 933. of the block forelocked, make signal (No. 1), that all is ready, the people on shore will haul the man to the land, and in the same manner will travel the snatch-block back, un- til every person is got from the wreck, as here represented. Remark. Crews have thus been brought in - - - - safety from distances exceeding 240 yards from the shore, and also from wrecks to the top of a cliff. le If the vessel stranded have women, children, sick or infirm persons on board, who could not go aloft, instead of a snatch-block and sling, a cot, with lashings, to pre- vent persons be- ing washed out, may be worked in the manner just described. • If the stranded vessel is driven - • among the rocks, and the persons in danger of being killed, or severely wounded from the surf dashing them with force against the rocky beach, a hammock stuffed with cork parings or shav- ings, as here repre- sented, would protect them from injury. If the people on shore bave only the - means of projecting a line for your preservation, they will make signal No. 4, for you to secure it, and draw on board so much as will fully reach from the vessel to the shore, to ensure a continued communication; with it make a clove hitch, which is to be put over the shoulders and arms of those to be brought on shore, and draw it tight, in manner here represented; and on your making signal £4 (No. 1,) that you are # ready, take care to clear 6 the wreck, and jump º overboard, when the people on shore will in- stantly haul you through the surf in safety. gº IRemark. Upwards of a 2-ºš 50 persons have been º &# saved in this manner, and among them one woman. board, from fear or agitation, be deprived of confidence in this mode of relief, a cushion, stuffed with fine cork parings, in the form represented, with lashings, re- Essº sº . so as to be easily adjusted to the body, would make a floating belt, in this manner, and effec- tually prevent the wearer from all danger or pos- sibility of drowning. º Remark. How important it would be to the preservation of life from shipwreck, if every owner of a vessel would consider it a duty he 9 Wes to humanity, to cause a hammock, and 97-8. - ... -- ... + * . . * r cushions, stuffed as described, to be kept on board his ship. The expense would be a mere trifle, as cork shavings or par- ings are considered of little or no value ; they would also be eminently useful in preventing a boat from sinking, by placing. them under the thwarts. - . If the distance from the shore is too great for the mortar to be tried, or if the shot falls short of the vessel, bend your light- est and best-stretched line to the buoy, veer it away gently, not paying out too fast ; buoy up your line every twenty fathoms, if you can, with corks or small spirit kegs, or any thing you may have fit for the purpose; the buoy will not reach the shore, but it will drive near enough to enable them to throw a grapnell shot over it, to draw it on shore: when this is done. look out for the signals as before, and be prepared in every way to obey them, and to act with the people on shore. Porm of Signals from the Shore.—The signal man will stand clear of the crowd, and place himself in front of a small flag. No. 1. Are you ready—or look out for the rope; we are pre- paring to launch a boat to you.' No. 2. Secure the rope; bend. No. 2. No. 3. No. 4. a warp or hawser to it, for us to draw it on shore for the boat— or for us to send you a stout rope, to be made fast to some firm parts of the wreck, for us to haul off a boat. No. 3. Haul away—to receive a stout rope, snatch-block with sling, cot, or hammock. No. 4. Haul on board enough of the line to ensure a continued communication—take care to clear the wreck. Signals to be made from the Ship, in Reply to any Directions,— No. 1. A man, in some conspicuous situation, will wave his arm three times horizontally, or across him, to denote yes, or weady. If he has a hat, let him take it in the hand he waves. No. 2. Three times up and down, to answer mo, or not ready. Trengrouse's Life Preserver.—Another contrivance for the preservation of lives in cases of shipwreck, has been invented by a Mr. Henry Trengrouse of Helstone, in Cornwall. In some respects it bears a resemblance to that of Captain Manby, but in others it is so essentially different, that a general outline of his plan merits an insertion in this work. “To render any contrivance,” he observes, “for the saving of lives in case of a wreck, extensively or generally useful, both reason and experience have convinced me that the apparatus must be kept on board. I therefore feel great satisfaction in reflecting on the success that has at last attended my labours, in devising the means to open the communication; my methods being such as induce me to believe they are not to be equalled by any other which is not on the same principle. I have not tried how far I can project a line, but I have no doubt of being able to do it with all necessary precision upwards of half a mile. With the other parts of the apparatus I am also fully satisfied. With their simplicity and portability are combined accommodation and security, and the whole may be used with all possible expedition. Mr. Trengrouse, it seems, was led into a train of reflections which have terminated in this happy result, by the loss of the Anson frigate, which was wrecked near the Loe Bar, not far from Helston, the place of his residence; in which ship about one hundred individuals, including the commander, perished. | His first attempt was simply to fasten the end of the line to a 11 E * 934 S H O S H O DICTIONARY OF MECHANICAL SCIENCE. piece of lead, and then to throw it on shore: but this he soon found could only be serviceable when the vessel lay contiguous to the land. His second scheme was that of hoisting a kite, and permitting it to hang over the land, and then causing it to fall where the people on the beach or rocks might seize it, and draw a line on shore. In this he at first placed much confi- dence; but after some time he saw reason to abandon it, as being too uncertain to justify dependence. His third method was that of a rocket, which he says has answered his most san- guine expectation. A line being thus thrown on shore by means of the rocket, and drawn by the people on the land, can soon bring from the wreck a rope, which, being made fast, and drawn as tensely as possible, will enable those on board to put his life-preserver into immediate use. “A model of the Preserver,” he observes, “ and a written de- scription of it, I shewed to a gentleman in this neighbourhood, who consulting with a friend of his who had formerly belonged to the Admiralty, was led with his friend to conclude that the invention was entitled to consideration. The former gentleman then caused it to be transmitted to Government, after which I heard no more about it. Probably the bustle created by the war in the naval department, and my not having made a sin- gle experiment with any part of the apparatus, to ascertain its practicability, as a recommendation for its adoption, might have been two reasons why it was not attended to. Several months had now elapsed without my hearing any thing about it, or making any experiments. But my feelings were as much alive as ever to the object I had in view; and although I did not suc- ceed in my first efforts, I proceeded under the unaltered con- viction that the principle was good, and that if the apparatus should become a portable part of the ship's equipment, in case of a wreck many lives might be preserved. To ascertain the most effectual means for accomplishing this desirable object, I tried many experiments; but though in some cases the use of a musket might answer every purpose, I finally gave the pre- ference to the rocket. With these, after making numerous attempts, I-have so far succeeded, as to believe, that there is not another man in the united kingdom who can project a line to an equal distance, and with equal precision and promp- titude, with any description of apparatus equal in portability, which is not on the same principle. The line which I project is adequate to draw a rope on shore sufficiently large to be used as a hauling-rope to draw persons through the water, or above the water on a hawser. If through the water, then a float is to be affixed on the rope, which may be done in a minute, and wrapped round the body of the person to be floated to land ; when, committing himself to the water, he will be instantly drawn to the shore. On being thus saved, the float must again be hauled to the wreck for the next person; and thus continue to pass and repass until all are secured. But if the stranded vessel should not go immediately to pieces, a hawser may be carried from the wreck and made fast on shore. This being drawn tight, all on board may be landed comfortably and quick- ly, by means of a chaise rolante, suspended on wheels that are curiously contrived to run upon the hawser. They are so con- structed that they may be worked with the utmost rapidity, without producing any observable friction. The chaise rolante is a safe, easy, and comfortable conveyance; it affords the ac- commodation of an arm-chair, and is perfectly secure for the infirm, the sick, or wounded, and also for women and children. It is so portable, that a child of three years of age may carry it under his arm. With these parts of the apparatus, I made my first experiments at Porthleaven in 1816. This was the first time that the float was ever in the water, and that the chaise rolante was ever suspended to a rope. A great number of spec- tators was present; among whom were several respectable gen- tlemen; to whom general satisfaction was given.” Of this expe- riment the following account was afterwards published by a Mr. Russell, who was a spectator of what he here relates. “On Friday last, Mr. Trengrouse publicly exhibited the use of his appa- ratus at PCrthleaven. From the western shore he threw several lines across the harbour, which went over the pier to some dis- tance on the outer side. The length of line projected was about 200 yards. He has so perfected this part of his plan, as certainly to render it superior to every other method. A float made of Gork was applied to the body of a man with his clothes on, who volunteered his services though the wind blew hard. He was soon hauled across the harbour in a buoyant state. The advantages of this float must be obvious to any one, who has ever witnessed the manner in which shipwrecked mariners are dragged through the foaming surf, from their perishing vessel to the shore. They are almost killed, that their lives may be saved. The same man who had thus been drawn across the harbour in the float, soon made a signal to return by the same route. He accordingly took his 'seat in the chaise rolante, sus- pended to a large rope, which had been drawn across the har- bour. In this he was conveyed over, and back again, in little more than two minutes.” After this first attempt, Mr. Trengrouse made several experi- ments before many scientific gentlemen, high in rank, both in the naval and military department, to whom his invention gave the fullest satisfaction. These have attested their approbation by their signatures, and the importance of his life-preserver has been so far appreciated as to procure for the inventor a dia- mond ring from the emperor of Russia. SHOAD, in Mining, stones containing ore mixed with rub- bish in a loose soil, and sometimes near the sigrface. When deep, the miners consider it as indicating that some vein is at no great distance. SHOAL, a term synonymous with shallow. SHOAR, a prop or stanchion fixed for support against a wall, or under a ship's sides or bottom, to support her when laid aground, or on the stocks, &c. * SHOE, a covering for the foot, usually made of leather. SHo E of the Anchor, a small block of wood, convex on the back, and having a hole sufficiently large to contain the point of the anchor-fluke on the fore side; it is used to prevent the anchor from tearing the planks on the ship's bow, when ascending or descending; for which purpose the shoe slides up and down along the bow, between the ſiuke of the anchor and the planks, as being pressed close to the latter by the weight of the former. To Shoe an Anchor, is to cover the flukes with a broad triangular piece of thick plank, whose area is greater than that of the flukes. Its use is to give the afichor a stronger and surer hold in very soft or oozy ground. Shoei NG of Horses, a term applied to the operation of fast- ening pieces of iron on the bottom parts of the hoofs, or that of nailing the shoes to their feet. This is an employment which requires much care, that the hoofs may not be injured, and that the animal may not be made lame. SHOOT, in Agriculture and Gardening, the young branch of any sort of plant, which is produced in one season. SHOPLIFTER, one who, under the pretence of purchasing goods in a shop, takes an opportunity to steal them. If the amount stolen be above five shillings, the thief is guilty of felony, without benefit of clergy, by 10 and 11 W. III. c. 22. . SHORE, in Agriculture, a sort of artificial drain, formed in low flat lands, for relieving them from the waters collected on their surface. Shore, the general name for the sea-coast of any country. Bold Shore, a coast which is steep and abrupt, so as to admit the near appoach of shipping, without exposing them to the danger of being stranded; and is used in contradistinction to a shelving shore. - SHOT, a missive weapon, discharged by the force of ignited powder from a fire-arm in battle ; of these there are various kinds, as, Round Shot, or Bullets, a ball or globe of iron, whose weight is in proportion to the bore of the cannon. Double-headed, or Bar Shot, are formed of a bar with a round head at each end, which fits the muzzle of the cannon. The middle is sometimes filled with a composition, and the whole covered with linen dipped in brimstone; so that the cannon, in firing, inflames the combustibles or composition of this ball, which sets fire to the sails of the enemy. One of the heads of this ball has a hole to receive a fuse, which communi- cating with the charge of the cannon, sets fire to the bullet. Chain Shot, consist of two balls chained together, being princi- pally designed to annoy the enemy by cutting her sails, rig- ging, &c. Grape Shot, is a combination of balls strongly corded in canvass upon an iron bottom, so as to form a sort of cylinder, whose diameter is equal to that of the ball which is adapted to the cannon. Case Shot, or Cannister Shot, are composed of a S. H. R. S I D DICTIONARY OF MECHANICAL SCIENCE. 935 great number of small bullets, put into a cylindrical tin box. They are principally used when very near, to clear the decks of the enemy. Besides these, there are others of a more perni- oious kind, used by privateers, pirates, &c. such are langrage shot, star shot, fire-arrows, &c. Star shot consists of four pieces of iron, whose bases, when separate, form the quadrant of a circle; so that the whole being joined, forms a cylinder equal to the shot of the cannon. Each of these pieces is fur- nished with an iron bar, the extremity of which is attached to a sort of link, as keys are strung upon a ring. Being dis- charged from the gun, the four branches or arms extend every way from the link in the centre. These also are chiefly in- tended to destroy the sails or rigging; but their flight and execution are very precarious at any tolerable distance. SHOVEL, in Agriculture, a well-known implement, with a long handle and wide blade, used instead of a spade, and by some labourers preferred to it. Shovels are differently formed, according to the purpose for which they are applied. SHOWER, a cloud resolved into rain, and discharged dur- ing a limited period on a certain tract of ground. SHRIMP, in Natural History, is the cancer crangan of Lin- maeus. This shell-fish inhabits the sandy shores of Great Bri- tain in vast quantities, and is reckoned a great delicacy. In form, the shrimp nearly resembles the lobster. SHRINE, in Ecclesiastical History, a case or box to hold the relics of some saint. SHROUDS, a range of large ropes extended from the mast- heads to the right and left sides of a ship, to support the masts, and enable them to carry sail, &c. The shrouds are always divided into pairs or couples, that is to say, one piece of rope is doubled, and the parts fastened together at a small distance from the middle, so as to leave a sort of noose or collar to fix upon the mast-head; the ends which reach to the deck have each a dead-eye turned in or fastened to them, by which they are extended to the channel. The shrouds, as well as the sails, &c. are denominated from the masts to which they belong; thus there are the main, fore, and mizzen shrouds; the main- top-mast, fore-top-mast, and mizzen-top-mast shrouds; and the main-top-gallant, fore-top-gallant, and mizzen-top-gallant shrouds. The Top-mast Shrouds are extended from the top- mast head to the edges of the tops by the foot-hook plates. See the article PLAT e. . The upper ends of the futtock-shrouds are furnished with iron hooks, which enter holes in the lower ends of the foot-hook plates, so that when the top-mast shrouds are set up or extended, the futtock shrouds require an equal tension. The Top-gallant Shrouds are extended to the cross- trees, where passing through holes in their ends, they continue over the futtock-staves of the top-mast rigging, and descending almost to the top, are set up by laniards passing through thim- bles instead of dead-eyes. Futtock or Foot-hook Shrouds are pieces of rope communicating with the futtock-plates above and the catharpings below, and forming ladders whereby the sailors climb up to the top-brim. Bowsprit Shrouds are shrouds put over the head of the bowsprit, and extended on each side | to the ship’s bows, to support the former. Bumkin Shrouds are strong ropes, fixed as stays or supports to the bumkin ends, to prevent their rising by the efforts of the fore-tacks upon them. Bentick Shrowds are strong ropes fixed on the futtock-staves of the lower rigging, and extending to the opposite channels, where they are set up by means of dead-eyes and laniards, in the same manner as the other shrouds; their use is to relieve or support the masts when the ship rolls. SH Roud, a shelter or cover, is used to denote the dress of the dead. If any person, in taking up the dead body, steals the shroud, the property of which remains in the executor, or the person who was at the charge of the funeral, it is felony. SHROVETIDE, the time immediately before Lent, and thus called by our ancestors, because employed in shriving, that is, in confessing their sins to the priest, in order to a more devout keeping of the ensuing Lent fast. Shrove Tuesday, is the day next before the beginning of Lent. SHROWDING of TRees, is the cutting or lopping off the top branches of such trees as are not fit for timber. Ash trees of this kind are sometimes called pollards. SHRUBS, in Botany and Vegetable Physiology, are com- of a more humble and slender form of growth than those deno- minated trees. . SHRUBBERY, a portion of ground planted with shrubs, trees, and flower plants, for the purpose of ornament. SHUCK, or SHock, in Agriculture, ten or twelve sheaves of corm placed together in an erect position, in a harvest field, with the corn upwards. It is sometimes called stoak. SHUME, Cr Ass HUME, an exceedingly hot wind of Africa, which, in the intermediate journeys between several parts of the great desert, or Sahara, occasions great inconvenience and distress to travellers. It sometimes wholly exhales the water carried in skins by the camels for the use of the travelling party; and instances have occurred, when five hundred dollars have been offered for a draught of water. From ten to twenty is a common price when a partial exhalation has taken place. In 1805, a caravan proceeding from Timbuctoo to Tafilet, was disappointed at finding no water at one of the usual watering places; and such was the calatuity, that it is said all the per- sons belonging to it, 2000 in number, and 1800 camels, perished by thirst. . SHUTTLE, in the Manufactures, an instrument much used by weavers, in the middle or near the end of which is an eye or cavity wherein is enclosed the spoul with the woof. • SHWAN PAN, the name of a Chinese instrument, which they use to assist them in their computations. It is composed of wires with beads upon them, which they move backwards or forwards, as occasion requires. See ABAcus. SIALAGOGUES, in Medicine, the name of all such simples or compounds as increase the flow of saliva. SIBERS, an infectious disease of a chronic nature, some- what resembling the syphilis, prevalent in the western parts of Scotland. It is said to be so denominated, from the appearance of a fungous exuberance from some of the cutaneous sores, not unlike a raspberry ; the word sibben, or sivven, being the Highland appellation for a wild raspberry. This disease is not of ancient date in Scotland. ! SIBSIT, in Zöology, an animal of the empire of Morocco, abounding in the mountains of Suse, of an intermediate species between the cat and the squirrel. - SIBYLS, ancient virgin prophetesses, whose fame has been spread throughout the world. Their books were held sacred in Rome, but were destroyed when the capitol was burnt, eighty-five years before Christ. Other copies were afterwards collected, but they are acknowledged to be imperfect, if not altogether fabulous. SICARII, in ancient history, assassins of Judea, who went about the country committing depredations, with short swords concealed under their garments. Josephus has described them in the most odious colours. SICE-ACE, a game with dice, and tables, whereat five may play, each having six men; and the last out, losing. At this game they load one another with aces; sixes bear away; and doublets drinks, and throws again. • SICERA, the Hellenist Jews give this name to any intoxi- cating liquor. Some have thought that it meant nothing but palm wine. SICKLE, in Agriculture, a toothed-hook used in reaping corn. There are great varieties in their construction. SICUB, a species of hawk, about the common size, well known in the Philippine islands. Its plumage is elegantly variegated with yellow, white, and black. SIDDOW, a peculiar kind of peas that boil, freely. It is well known in some districts in Gloucestershire. SIDEREAL DAY, is the time in which any star appears to revolve from the meridian to the meridian again; which is 23 hours 56'4”6 of mean solar time; there being 366 sidereal days in a year, or in the time of 365 diurnal revolutions of the earth. SIDERATION, the blasting or blighting of trees, plants, &c. by eastern winds, excessive heat, continued drought, and similar causes. SIDERITES a name which some authors give to the load- Stone. SIDERITIS, a plant, supposed to be efficacious for stanch- ing of blood and healing of wounds, if newly made. SIDEROMANTIA, an ancient kind of divination by laying laonly understood to be plants with a perennial woody stem, I straws upon red-hot iron. By observing their figures, bend- & 936 S I Gº S I G DICTIONARY OF MECHANICAL SCIENCE, ings, sparkling, and burning, the imaginary prognostics were obtained. SIDES-MEN, or SYNoD's Men, persons who in large parishes are appointed to assist the churchwardens in their inquiry and presentments of such offenders to the ordinary, as are punishable in the spiritual court. - SLEGE, in the art of war, the encampment of an army before a fortified place, with a design to take it. * SIENITE, a stone composed of felspar and hornblende, and sometimes quartz and black mica. The transitions by which granite passes into sienite, and the latter into porphyry, trap, and basalt, are gradual, and in some rocks almost impercep- tible. These changes are principally eſſected by an intermixture of the mineral already described under the name of Hornblende. SIERRA, is a word used for hill in various parts of the world, particularly on the west coast of Africa, on the north coast of South America, and on the coasts of Chili and Peru on the South Pacific ocean. SIERRILLO, the term for a little hill, being a diminutive from Sierra; in which sense it is used on the south-west coast of South America also. SIEVE, or SEAve, an instrument serving to separates the fine from the coarse parts of powders, liquors, &c. and to cleanse pulse and corn from dust, light grain, &c. SIGAH Gush, in Zöology, the name of a Persian animal of the cat kind, and no way differing from the lynx, only that it has no spots. SIGHING, an effort of nature, by which the lungs are put into quicker motion, and become more dilated, so that the blood passes more freely, and in greater quantity, to the left auricle, and thence to the ventricle. SIGHT. See EYE. SIGHTS of A QUADRANT, &c. thin pieces of brass raised perpendicularly on its side, or on the index of a theodolite, circumferentor, &c. SIGN, in Astronomy, a constellation containing a twelfth part of the zodiac, or thirty degrees. SIGNALS, certain notices used to communicate intelligence to distant objects. At sea they are made by firing artillery, displaying flags and pendants, lanterns or fire-works, as rockets and false-fires, and these are combined by multiplication and repetition; by which combination of signals, previously known, the admiral conveys orders to his fleet, every squadron, every division, and ship, of which, has its particular signal. Every ship to which a signal is made, immediately answers it by hoisting some particular flag, to shew that she has received and understands the order thereby conveyed. All signals may be reduced into three different kinds, viz. those which are made by the sound of particular instruments, as the trumpet, horn, or fife; to which may be added, striking the bell, or beating the drum. Those which are made by displaying pen- dants, ensigns, and flags of different colours; or by lowering or altering the position of sails; and, lastly, those which are exe- cuted by rockets of different kinds, by firing cannon or small arms, by artificial fire-works, and by lanterns. All signals, to be effectual, must be simple, and composed in such a manner as to express the same signification at whatever mast-head or yard-arm they may be displayed from. They should be issued without precipitation, exposed in a conspicuous place, so as to be seen at a distance, and sufficient time should be allowed to observe and obey them. Signals are very numerous and important, being all appointed and determined by order of the Iord high admiral, or lords of the admiralty, and communicated in the instructions sent to the commander of every ship of the -ſleet or squadron, before their putting out to sea. Few subjects have more seriously engaged the attention of nautical men than that of signals; the labour, however, and study that has hitherto been expended on them, appear, even in the opinion of the inventors themselves, not to have been completely pro- ductive of that precision and correctness in conveying orders which is certainly the grand desideratum. The object is un- doubtedly of the first consequence to a maritime power; the greatest inconveniencies have at different times arisen, as well in action as on other occasions, from the imperfect state of the code, and consequently every attempt to improve its effects, and diminish its imperfections, is truly laudable and worthy of consideration. The firing of great guns is common in the day, night, or in a fog, to make or confirm signals; yet it must be confessed, that too great a repetition is apt to introduce mis- takes and confusion, as well as to discover the track of the squadron. The report and flight of the rockets is liable to the same objection, when at a short distance from the enemy. Signals by Day.—When the commander-in-chief would have them prepare for sailing, he first loosens his fore-top-sail, and then the whole fleet are to do the same. When he would have them unmoor, he loosens his main-top-sail and fires a gun, which in the royal navy is to be answered by every flag-ship. When he would have them weigh, he loosens his fore-top-sail and fires a gun, and sometimes hauls home his sheets; the gun is to be answered by every flag-ship, and every ship to get to If with the leeward side, the stern- most ship is to weigh first. When he would have the wea- thermost and headmost ships to tack first, he hoists the union- flag at the fore-top-mast head, and fires a gun, which each flag-ship answers; but if he would have the sternmost and leewardmost ships tack first, he hoists the union-flag at the mizzen-top-mast head, and fires a gun; and when he would have all the whole fleet tack, he hoists an union, both on the fore and mizzen-top-mast heads, and fires a gun. When, in bad weather, he would have them wear and bring to the other tack, he hoists a pendant on the ensign-staff and fires a gun, and sail as soon as she can. then the leeward most and sternmost ships are to wear first and bring on the other tack, and lie by, or go on with an easy sail till he comes ahead : every flag is to answer with the same signal. If they are lying or sailing by a wind, and the admiral would have them bear up and sail before the wind, he hoists his ensign and fires a gun, which the flags are to answer; and then the leeward most ships are to bear up first, and to give room for the weathermost to wear, and sail before the wind with an easy sail, till the admiral comes ahead. But if it should happen, when the admiral has occasion to wear, and sail upon the wind, that both jack and ensign be abroad, he will haul down the jack before he fires the gun, to wear and keep it down till the fleet is before the wind. When they are sailing before the wind, and he would have them bring to, with the starboard tacks aboard, he hoists a red flag at the flag-staff, on the mizzen-top-mast head, and fires a gun. But if they are to bring to with the larboard tack, he hoists a blue flag at the same place, and fires a gun, and every ship is to answer the gun. When any ship discovers land, he is to hoist his jack and en- sign, and keep it abroad till the admiral or commander-in-chief answers him by hoisting his ; on sight of which he is to haul down his ensign. If any discover danger, he is to iack and bear up from it, and to hang his jack abroad from the main- top-mast cross-trees, and fire two guns; but if he should strike or stick fast, then, besides the same signal with his jack, he is to keep firing till he sees all the fleet observe him, and avoid the danger. When any sees a ship or ships more than the fleet, he is to put abroad his ensign, and there keep it, till the admiral's is out, and then to lower it, as often as he sees ships, and stand in with them, that so the admiral may know which way they are, and how many; but if he be at such a distance that the ensign cannot well be discovered, he is then to lay his head towards the ship or ships so descried, and to brail up his lower sails, and continue hoisting and lowering his top-sails, and making a waft with his top-gallant-sails, till he is perceived by the admiral. When the admiral would have the vice- admiral, or him that commands in the second post of the fleet, to send out ships to chase, he hoists a ſlag, striped white and red, on the flag-staff, at the fore-top-mast head, and ſires a gun. But if he would have the rear admiral do so, he then hoists the same signal on the flag-staff at the mizzen-top-mast head, and fires a gun. When the admiral would have any ship to chase to windward, he makes a signal for speaking with the captain, and he hoists a red flag in the mizzen-shrouds, and fires a gun; but, if to chase to leeward, a blue flag; and the same signal is made by the ſlag in whose division the ship is. When he would have them give over the chase, he hoists a white flag on the flag-staff at the fore-top-mast head, and fires a gun; which signal is to be made also by that flag-ship which is nearest the ship that gives the chase, till the chasing ship sees the signal. In case of springing a leak, or any other disaster that disables their S I G. S I G 937 DICTIONARY OF MECHANICAL SCIENCE. ship from keeping company, they are to haul up their courses, and fire two guns. When any ship would speak with the admiral, he must spread an English ensign from the head of his main and fore-top-mast downwards on the shrouds, lower- ing his main or fore-top-sail, and firing guns till the admiral observes him; and if any ship perceive this, and judge the admiral does not, that ship must make the same signal to acquaint the admiral therewith, who will answer by firing one gun. When the admiral would have the fleet to prepare to anchor, he hoists an ensign, striped red, blue, and white, on the ensign-staff, and fires a gun, and every flag-ship makes the same signal. If he would have the fleet moor, he hoists his mizzen-top-sail with the clue lines hauled up, and fires a gun. If he would have the fleet cut or slip, he loosens both his top- sails, and fires two guns; and then the leeward ships are to cut or slip first, to give room to the weathermost to come to sail. So, if he would have any particular ship to cut or slip, and to chase to windward, he makes the signal for speaking with that ship, hoists a red flag in the mizzen-shrouds, and fires a gun; but if the ship is to chase to leeward, he hoists, a blue ſlag as before. If he would have the fleet exercise their small arms, he hoists a red ſlag on the ensign-staff, and fires a gun; but if the great guns, then he puts up a pendant over the red flag. Signals by Night.—Night signals should be used as little as pos- sible, since they are frequently misunderstood. Of necessity, they must be composed of either sound or light, or the two blended together. Those to be observed at an anchor, weighing anchor, and sailing, are as follow : when the admiral would have the ſleet to unmoor and ride short, he hangs out three lights, one over another, in the main-top-mast shrouds, over the constant light in the main-top, and fires two guns, which are to be answered by flag-ships; and each private ship hangs out a light in the mizzen-shrouds. N. B. All guns, fired for signals in the night, must be fired on the same side, that they may make no altera- tion in the sound.—When he would have them weigh, he hangs a light in the main-top-mast shrouds, and fires a gun, which is to be answered by all the flags, and every private ship must hang out a light in her mizzen-shroud. When he would have them tack, he hoists two flags on the ensign-staff, one over another, above the constant light in his poop, and fires a gun, which is to be answered by all the flags; and every private ship is to hang out a light extraordinary, which is not to be taken in till the admiral takes in his. After the signal is made, the leewardmost and sternmost ships must tack as fast as they can, and the sternmost flag-ship, after she is about on the other tack, is to lead the fleet, and her they are to follow, to avoid running foul of one another in the dark. When he is upon a wind, and would have the fleet veer and bring to on the other tack, he hoists up one light on the mizzen-tack, and fires three guns, which is to be answered by the flag-ships, and then every private ship must answer with one light at the mizzen-peek. The sternmost and leeward most ships are to bear up as soon as the signal is made. When he would have them in blowing weather to lie by, short, or a-hull, or with the head-sails braced to the mast, he will form lights of equal height, and fire five guns, which are to be answered by the flag-ships, and then every private ship must shew four lights; and after this, if he would have them make sail, he then fires ten guns, which are to be answered by all the flags, and then the headmost and weathermost ships are to make sail first. When the fleet is sailing large, or before the wind, and the admiral would bring them to, and lie by with their starboard-tacks aboard, he puts out four lights in the fore-shrouds, and fires six guns; but if with the larboard-tacks aboard, he fires eight guns, which are to be answered by the flag-ships, and every private ship must shew four lights. The windward ships must bring to first. Whenever the admiral alters his course, he fires one gun, without altering his lights, which is to be answered by all the flag-ships. If any ship have occasion to lie short, or by, after the fleet has made sail, he is to fire one gun, and shew three lights in the mizzen-shrouds. When any one first discovers land, or danger, he is to shew as many signs as he can, to fire one gun, and to tack or bear away from it; and if any one happens to spring a leak, or be disabled from keeping company with gº." he hangs out two lights of equal height, and fires guns till he is relieved by some ship of the fleet. If any one discovers a ſleet, he is to fire guns, make false fires, put one light out on the main-top, three on the poop, to steer after them, and to continue firing of guns, unless the admiral calls him off by steering another course, and firing two or three guns; for then he must follow the admiral. When the admiral an- chors, he fires two guns, a small space of time one from the other, which are to be. answered by the flag-ships, and every private ship must shew two lights. When the admiral would have the fleet to moor, he puts a light on each top-mast head, and ſires a gun, which is to be answered by the flag-ships, and every private ship is to shew one light. If he would have them lower their yards and top-masts, he hoists one light upon his ensign-staſi, and fires one gun, which is to be answered by the flag-ships, and every private ship is to shew one light. And when he would have them hoist their yards and top-masts, he puts out two lights, one under the other, in the mizzen-top-mast shrouds, and fires one gun, which is to be answered by the flag-ships, and each private ship must shew one light in the mizzen-shrouds. If any strange ship be discovered coming into the fleet, the next ship is to endeavour to speak with her, and bring her to an anchor, and not suffer her to pass through the fleet. And if any one discovers a fleet, and it blows so hard that he cannot come to give the admiral timely notice, he is to hang out a great number of lights, and to continue firing gun after gun, till the admiral answers him with one. When the admiral would have the fleet to cut or slip, he hangs out four lights, one at each main-yard-arm and at each fore-yard-arm, and fires two guns, which are to be answered by the flag-ships, and cvery private ship is to shew one light. Signals in a Fog.—Fog signals can only be composed of sound at different intervals. When, therefore, the admiral would have them weigh, he fires ten guns, which every flag-ship is to answer. To make them tack, he fires four guns, which are to be answered by the flag-ships, and then the leewardmost and sternmost ships must tack first, and after they are about, to go with the same sail they tacked with, and not to lie by, expecting the admiral to come a-head, and this is to avoid the danger of running foul of one another in thick weather. When the admiral brings to, and lies with his head-sails to the mast, if with the starboard tack aboard, he ſires six guns; but if with the larboard tack, he fires eight guns, which the flag-ships are to answer. And, after this, if he make sail, he fires ten guns, which the flag-ships must answer, and then the headmost and weathermost ships are to make sail first. If it grow thick and foggy weather, the admiral will continue sailing with the same sail set that he had before it grew foggy, and will fire a gun every hour, which the flag-ships must answer by firing of muskets, beating of drums, and ringing of bells. But if he be forced to make either more or less sail than he had when the fog began, he will fire a gun every half hour, that the fleet may discern whether they come up with the admiral, or fall astern of him; and the ſlags and private ships are to answer as before. If any one discovers danger which he can avoid, by tacking and standing from it, he is to make the signal for tacking in a fog; but if he should chance to strike and stick fast, he is to fire gun after gun, till he thinks the rest have avoided the danger. When the admiral would have the fleet to anchor, he fires two guns, which the flags are to answer ; and after he has been half an hour at anchor, he will ſire two guns more, to be an- swered by the flags, as before, that all the fleet may know it, Signals for calling Officers on board the Admiral.—When the admiral puts abroad an union, ſlag in the mizzen-shrouds, and fires a gun, all the captains are to come aboard him ; and if with the same signal there be also a waft made with the ensign, then the lieutenant of each ship is to come on board. If an ensign be put abroad in the same place, all the masters of the ships of war are to come on board the admiral. If a standard on the flag-staff be hoisted at the mizzen-top-mast head, and a gun fired, then all the flag-officers are to come on board the admiral. If the English flags only, then a standard in the mizzen-shrouds, and fire a gun ; if the flags and land general officers, then the admiral puts abroad a standard at the mizzen- top-mast head, and a pendant at the ...izzen-peek, and fires a gun. If a red ſlag be hoisted in the mizzen-shrouds, and a gun fired, then the captains of his own squadron are to come aboard 11 F - 938 S I. G. S H. G. DICTIONARY of MECHANICAL scIENCE. the admiral ; and if with the same signal there be also a waft with the ensign, the lieutenant of each ship must come on board. If he hoists a white flag, as before, then the vice-ad- miral, or he that commands in the second post, and all the captains in his squadron, are to go on board the admiral ; if a blue flag, &c. then the rear admiral, and the captains of his squadron, must come on board; and if a waft, as before, the lieutenants. When a standard is hoisted on the ensign-staff, and a gun fired, the vice and rear admirals must come on board the admiral's ship. When the admiral would speak with the captains of his own division, he will hoist a pendant on the mizzen-peek, and fire a gun; and if with the lieutenants, a waft is made with the ensign, and the same signal; for whenever he would speak with the lieutenants of any particular ship, he makes the signal for the captain, and a waft also with the en- sign. When the admiral would have all the tenders in the fleet come under his stern, and speak with them, he hoists a flag, yellow and white, at the mizzen-peek, and fires a gun; but if he would speak with any particular ship's tender, he makes a signal for speaking with the captain she tends upon, and a waft with a jack. If all the pinnaces and barges are to come on board, manned and armed, the signal is a pendant on the flag-staff, hoisted on the mizzen-top-mast head, and a gun fired; and if he would have them chase any ship, vessel, or boat in view, he hoists the pendant, and fires two guns. The signal for the long-boats to come on board him, manned and armed, is the pendant hoisted on the flag-staff, and the mizzen-top-mast head, and a gun fired; and if he would have them chase any ship, vessel, or boat, in open view, without coming on board him, he hoists the pendant as aforesaid, and fires two guns. When the admiral would have all the boats in the flect to come on board him, manned and armed, he hoists a pendant on the flag-staff, both on the fore-top-mast and mizzen-top-mast head, and ſires one gun; but if he would have them chase, he hoists his pendant, as before, and fires two guns. When the admiral would speak with the victualler or his agent, he puts an English ensign in the mizzen-top-mast shrouds; and when with him that has the charge of the gunner's stores, he will spread an ensign at his main-top-sail yard-arm. - Signals for Battle.—When the admiral would have the ſlee form a line of battle, one ship ahead of another, he hoists an union-flag at the mizzen-peck, and fires a gun, and every flag- ship does the same. But when they are to form a line of battle, one abreast of another, he hoists a pendant with the union- flag, &c. When he would have the admiral of the white, or him that commands in the scoond post, to tack, and cndeavour to gain the wind of the enemy, he spreads a white flag under the flag at the main-top-mast head, and fires a gun ; and when he would have the vice-admiral of the blue do so, he doth the same with the blue flag. If he would have the vice-admiral of the red do so, he spreads a red flag from the cap, on the fore- top-mast head, downward on the back stay; if the vice-admiral of the blue, he spreads a blue flag, &c. and fires a gun. If he would have the rear-admiral of the red do so, he hoists a red flag at the flag-staff at the mizzen-top-mast head; if the rear- admiral of the white, a white flag : if the rear-admiral of the bine, a blue flag, and under it a pendant of the same colour, with a gun. If he be to leeward of the fleet, or any part of it, and he would have them bear down into his wake or track, he hoists a blue flag at the mizzen-peek, and fires a gun. If he would be to leeward of the enemy, and his fleet, or any part of it, be to leeward of him, in order to bring those ships into a line, he bears down with a blue flag at the mizzen-peek, under the union-flag, which is the signal for battle, and fires a gun ; and then those ships that are to leeward of him must endeavour to get into his wake or track, according to their station in the line of battle. When the fleet is sailing before the wind, and he would have him who commands in the second post, and the ship of the starboard quarter, to clap by the wind and come to the starboard tack, he hoists a red flag at the mizzen-top-mast head; but a blue one, with a gun, if he would have ships of the Jarboard quarter come to the Jarboard tack. If the van are to tack first, he spreads the union-flag at the flag-staff, on the fore-top-mast head, and fires a gun, if the red flag be not abroad; but if it be, then he lowers the fore-top-sails a little, and the union is spread from the cap of the fore-top-mast downwards, and every flag-ship does the same. If the rear be to tack first, he hoists the union-flag on the staff-flag at the mizzen-top-mast head, and fires a gun, which all the flag-ships are to answer. If all the flag-ships are to come into his wake or track, he hoists a red flag at his mizzen-peek, and fires a gun, and all the flag-ships must do the same. If he would have him who commands in the second post of his squadron to make more sail, though himself shorten sail, he hoists a white flag on the ensign-staff; but if he who commands in the third post be to do so, he hoists a blue flag, and fires a gun, and all the flag- ships must have the same signal. Whenever he hoists a red flag on the flag-staff at the fore-top-mast head, and fires a gun, every ship in the fleet must use their utmost endeavour to en- gage the enemy in the order prescribed them. When he hoists a white flag at his mizzen-peek, and fires a gun, then all the small frigates of his squadron that are not of the line of battle are to come under the stern. If the fleet be sailing by a wind in the line of battle, and the admiral would have them brace their head-sails to the mast, he hoists up a yellow flag on the flag-staff at the mizzen-top-mast head, and fires a gun, which the flag-ships are to answer, and then the ships in the rear must brace first. After this, if he would have them fall their head-sails and stand on, he hoists a yellow flag on the flag-staff of the forc-top-mast head, and fires a gun, which the flag-ships must answer, and then the ships in the van must fall first and stand on. If when this signal is made the red ſlag at the fore- top-mast head be abroad, he spreads the yellow flag under the red. If the fleets, being near one another, and the admiral would have all the ships to tack together, the sooner to lie in a posture to engage the enemy, he hoists an union-flag on each flag-staff at the fore and mizzen-top-mast heads, and fires a gun; and all the flag-ships are to do the same. The fleet being in a line of battle, if he would have the ship that leads the van hoist, lower, set, or haul up any of the sails, he spreads a yellow flag under that at his mizzen-top-mast head, and fires a gun, which signal the flag-ships are to answer, and then the admiral will hoist, lower, set, or haul up the sail which he would have thc ship that leads the van do, which is to be answered by the flag- ships of the ſleet. When the enemy runs, and he would have the whole fleet follow them, he makes all the sail he can after them himself, takes down the signal for the line of battle, and fires two guns out of his bow-chase, which the flag-ship answers ; and then every ship is to endeavour to come up with and board the enemy. When he would have the chase given over, he hoists a white flag at the fore-top-mast head, and fires a gun. If he would have the red squadron drawn into a line of battle, one abreast of another, he puts abroad a flag, striped red and white, on the flag-staff at the main-top-mast head, with a pen- dant under it, and ſires a gun. If the white, or second squadron, be to do so, the flag is striped red, white, and blue ; if the blue, or third squadron, be to do so, the flag is a Genoese ensign and pendant; if they are to draw into a line of battle, one ahead of another, the same signals are made without a pendant. If they are to draw into the line of battle, one astern of another, with a large wind, and he would have the leaders go with the star- board tacks aboard by the wind, he hoists a red and white flag at the mizzen-peek, and fires a gun ; but if they should go with the larboard tacks aboard by the wind, he hoists a Geonese flag at the same place, which signals, like others, must be answered by the flag-ships. wº g Signals win Distress and for Relief–Signals betokening dis- tress have been aircady intimated in the foregoing; we shall, therefore, subjoin an account of signals in casc ships or vessels are perceived in distress. The following are the charitable institutions established at Bembrough Castle, in the county of Northumberland, for the assistance and relief of distressed marincrs, published by the direction of the trustees of Nathaniel, late Lord Crewe, with the approbation of the master, pilots, and seamen of the Trinity House, Newcastle. 1. A gun, (a nine-pounder) placed at the bottom of the tower, to be fired as a signal in case any ship or vessel be observed in distress ; viz. once, when any ship or vessel is stranded, or wrecked, upon the islands, or any adjacent rock. Twice, when any ship or vessel is stranded, or wrecked, behind the castle, or to the northward of it. Thrice, when any ship or vessel is stranded, or wrecked, to the southward of the castle, in order that the S I L S I L DICTIONARY OF MECHANICAL SCIENCE. 939 Custom-house officers and the tenants, with their servants, may hasten to give all possible assistance, as well as to prevent the wreck from being plundered. 2. In every great storm two men on horseback are sent from the castle to patrole along the coast from sun-set to sun-rise, that in case of any accident, one may remain by the ship, and the other return to alarm the castle. Whoever brings the first notice of any ship or vessel being in distress, is entitled to a premium in proportion to the distance from the castle; and if between twelve o'clock at night and three o’clock in the morning, the premium to be doubled. 3. A large flag is hoisted when there is any ship or vessel seen in distress upon the Fern Islands, or Staples, that the sufferers may have the satisfaction of knowing their distress is perceived from the shore, and that relief will be sent them as soon as possible. In case of bad weather, the flag will be kept up, a gun fired morning and evening, and a rocket thrown up, every night from the north turret, till such time as relief can be sent. There are also signals to the Holy Island fishermen, who, from the advantage of their situation, can put off for the islands at times when no boat from the main land can get over the breakers. for the islands, to give their assistance to ships or vessels in distress, and provisions are sent in the boat. 4. A bell on the south turret will be rung in every thick fog, as a signal to the fishing-boats; and a large swivel fixed on the east turret, will be fired every fifteen minutes, as a signal to the ships with- out the islands. 5. A large weather-cock is fixed on the top of the flag-staff, for the use of the pilots. 6. A large speaking- trumpet is provided, to be used when ships are in distress near the shore, or are run aground. 7. An observatory, or watch- tower, is built on the east turret of the castle, where a person is to attend every morning at daybreak during the winter sea- son, to look out if any ships are in distress. 8. Masters and commanders of ships and vessels in distress, are desired to make such signals as are usually made by people in their me- Hancholy situation. Besides these signals for affording relief, stores, provisions, necessary articles for raising ships that are stranded, in order to their being prepared. Coffins for the dead, &c. are also provided. - Day SIGNALs, are usually made by flags and pendants, some- times accompanied with one or more guns. Night SIGNALs, are either lanterns disposed in certain figures, as lines, squares, and triangles, or are made with false fires, &c. Fog SIGNALs, consist of operations which emit sound, as fir– ing cannon or muskets, beating drums, ringing bells, &c. SIGNATURE, a subscription, or putting one’s name at the bottom of an act or deed, in personal hand writing, or mark. SIGNATURE, in Printing, is a letter put at the bottom of the first page, at least, in each sheet, as a direction to the binder in folding, gathering, and collating them. SIGNET. See Sign MANUAL. SIGNIFICATION, the sense or meaning of a word, phrase, emblem, or device. The signification of the ancient hierogly- phics is but little known. SIGNINUM, among the Romans, was a kind of pavement much esteemed. It was made of powdered shells mixed with lime. - SIGN-MANUAL, in Law, is used to signify a bill or writing signed by the king’s own hand. SIKE, a term provincially applied to a little rill, a water fur- row, and a gutter. SIL, in Canals, the bottom timbers of sluices, lockgates, &c. S1 L, in Natural History, peculiar kinds of ochres, well known as valuable paints. SIDICA, SILEX, SILICIUM, or Silicious Earth, is one of the most abundant substances in nature, and is the chief component part of sand, sandstone, flints, granite, quartz, porphyry, rock crystal, agates, and many precious stones. It is the substance of which the solid frame of many mountains is composed, and it probably is so of a great part of the globe itself. Its specific gravity is about 2 66. Silex when perfectly pure is a fine powder, hard, insipid, and without smell; rough to the touch, and scratches and wears away glass. When mixed with water, It does not form an adhesive soft mass, and soon falls to the bèttom, leaving the water clear. If silex be very minutely divided, it may be dissolved in water to a very small degree. Premiums are given to the first boats that put off Although we cannot dissolve silica artificially, we find it done by nature. The Bath waters, and other mineral springs, con- tain silex in solution in a very small portion. The great springs and waterspouts of Geyser in the island of Iceland, which project the water ninety feet high, contain silex dissolved by some process of nature, for the water falling down deposits such a quantity of silicious earth as to form a sort of cup around the spring. In this process the pressure and heat of the water may, perhaps, greatly contribute to the effect. Silica is a very necessary component part in good mortar. When reduced to minute parts either by nature or art, it is employed in making Stone-ware. It is the chief substance of which glass is made, for which purpose it is smelted with the alkaline salts in a great heat. A variety of these salts are used for the purpose, and metals are also frequently employed. Silica, it is probable, is composed of oxygen and a metallic basis. SILK, the web or envelopment of the caterpillar, of a species of moth called the Phalena mori, which being convertible to various purposes of utility and elegance, forms an important article in commerce, as the material of a valuable manufacture. The caterpillar, or silk-worm, when full grown, encloses itself in a loose web, in the midst of which it forms a much closer case or covering, of an oval form, and varying in colour from white to a deep orange, but usually of a bright yellow colour. In this case, or ball, the animal becomes a crysalis, and remains enclosed about fifteen days; when having resumed active life, in the form of a moth, it makes a hole at one end of its prison, and comes out. This, as it destroys the silk-ball, is prevented, in those countries where silk is cultivated, by kiliing the cry- salides by means of heat. The culture of silk varies but little in different countries, and does not require any great degree of skill, or considerable capital ; and as silk-worms, cherished with care, and attended as matters of curiosity, were found to thrive and multiply in England, it is not surprising that attempts should have been made to establish the culture of it in this country. The success of Henry IV. of France, in extending the culture of silk, which before his time had been confined to a few districts of that kingdom, excited in James I. an active zeal for the introduction of it here. The insurmountable obstacle to raising silk in Great Britain is the climate, which is too cold and wet; and though expedients might be adopted to obviate these in- conveniencies, they would render the culture of the article, on a large scale, by far too expensive. In the British settlements in the East Indies, the culture of silk has been long established, particularly in the island of Cossimbwzar and its neighbour- hood, in the province of Bengal; and since, about the year 1760, when the company became the rulers of the country, and adopted a new system of trade for the purpose of realizing the surplus revenue, the culture of raw silk has been promoted, and the quantity considerably increased. Of late years, considerable attention has been paid both to the quality of the silk, and to the mode of reeling it, by which it has been very materially im- proved, so as to rival, in most respects, the produce of Italy, SILVER, is the whitest of all metals, considerably harder than gold, very ductile and malleable, but less malleable than gold; for the continuity of its parts begins to break when it is hammered out into leaves of about the hundred and sixty thou- sandth part of an inch thick, which is more than one-third thieker than gold leaf; in this state it does not transmit the light. Its specific gravity is from 104 to 10:5. It ignites be- fore melting, and requires a strong heat to fuse it. The air alters it very little, though it is disposed to obtain a thin purple or black coating from the sulphurous vapours which are emitted from animal substances, drains, or putrefying matters. This coating, after a long series of years, has been observed to scale off from images of silver exposed in churches; and was found, on examination, to consist of silver united with Sulpliur. Silver is soluble in the sulphuric acid when concentrated and boiling, and the metal in a state of division. The muriatic acid does not act upon it, but the nitric acid, if somewhat, diluted, dis- solves it with great rapidity, and with a plentiful disengagement of nitrous gas. - SILVERING, performed as gilding, is the application of silver leaf to wood, paper, and other substances.—To Silver Copper or Brass, cleanse the metal with aqua fortis, by washing it lightly, and then plunging it into water; or by scouring it 940 S I L S I M DICTIONARY OF MECHANICAL SCIENCE, with salt and tartar with a wire brush. Dissolve silver in aqua fortis, put copper into the solution; this will precipitate the silver in the state of a metallic powder. Take about twenty grains of this silver powder, and mix with it two drachms of tartar, the same quantity of common salt, and half a drachm of alum; rub the articles with this composition till, they are perfectly white, then brush it off, and polish it with leather. Another method: precipitate silver from its solution in aqua fortis by copper, as before ; to half an ounce of this silver add common salt and sal ammoniac, of each two ounces, and one drachm of corrosive sublimate; rub them together, make them into a pasto with water; and with this, copper utensils of every kind, that have been previously boiled with tartar and alum, are rubbed ; after which they are made red hot and polished.— To Silver Dial-plates of Clocks, &c. take half an ounce of silver leaf, add to it an ounce of double-refined aqua fortis, put them into an earthen pot, place them over a gentle fire till the whole is dissolved; then take off the pot, and mix the solution in a pint of clear water; after which, pour it into another clean vessel, to free it from grit or sediment; add a spoonful of common salt, and the acid, which has now a green tinge, will immediately let go the silver particles, which form themselves into a white curd ; pour off the acid, mix the curd with two ounces of salt of tartar, half an ounce of whiting, and a large spoonful of salt, and mix it well up together, when it will be ready for use. Having cleared the brass from scratches, rub it over with a piece of old hat and rotten-stone, to clear it from all greasiness, and then rub it with salt and water with your hand, take a little of the composition just described on your fin- ger, rub it over where the salt has touched, it will adhere to the brass, and completely silver it. Then wash it well with water, to take off what aqua fortis may remain in the composition; when dry, rub it with a clean rag, and give it one or two coats of varnish, prepared according to the directions already given. This silvering, though not durable, may be improved by heating the article, and repeating the operation till the covering seems sufficiently thick.-Silver Plating, the coat of silver applied to the surface of the copper by the means just mentioned, is thin, and not durable. A method more substantial is as follows: form small pieces of silver and copper, tie them together with wire, putting a little borax between, (the proportion of silver may be to that of the copper as 1 to 12;) subject them to a white heat, when the silver will be firmly fixed to the copper. The whole is now passed between rollers, till it be of the re- quired thickness for manufacturing articles of use or orna- ment.--To make French Plate, heat the copper articles intended to be plated, and burnish silver-leaf on it with a burnisher.— To make Shell Silver, grind leaf-silver with gum-water or honey; wash away the gum or honey, and the powder that remains is used with gum-water, or glaire of eggs laid on with a hair pencil.--To Silver Looking-glasses, you must be prepared with the following articles: First, a square marble slab, or smooth Stone, well polished, and ground exceedingly true, the larger the better, with a frame round it, or a groove cut in its edges, to keep the superfluous mercury from running off. Secondly, lead weights covered with cloth, to keep them from scratching the glass, from one pound weight to twelve pounds each, according to the size of the glass which is laid down. Thirdly, rolls of tinfoil. Fourthly, mercury or quicksilver, with which you must be well provided; then proceed as follows: the tinfoil is cut a little larger than the glass every way, and laid flat upon the stone, and with a straight piece of hard wood, about three inches long, stroked every way, that there be no creases or wrinkles in it; a little mercury is then dropped upon it, and with a piece of cotton, wool, or hare's foot, spread it all over the foil, so that every part may be touched with the mercury: then keeping the marble slab nearly level with the horizon, pour the mercury all over the foil, cover it with a fine paper, and lay two weights near its lower end, to keep the glass steady, while you draw the paper from between the silver foil and the glass, which must be laid upon the paper. As you draw the paper, you must take care that no air-bubbles be left, for they will always appear, if left in at the first; you must likewise be sure to make the glass as clean as possible on the side intended to be silvered, and have the paper also quite clean, otherwise, when you have drawn the paper from under it, dull white | streaks will appear, which are very disagreeable. After the paper is drawn out, place weights upon the glass, to press out the superfluous mercury, and make the foil adhere: when it has lain about seven hours in this situation, raise the stone about two or three inches at its highest end, that as much of the mercury may run off as possible; let it remain two days before you venture to take it up; but before you take the weights off, brush the edges of the glass gently, that no mercury may adhere to them; then take it up, and turn it directly over, with its face-side downward, but raise it by degrees, that the mer- cury may not drip off too suddenly; for if, when taken up, it is immediately set perpendicular, air will get in between the foil and the glass at the top, as the mercury descends to the bot- tom, and your labour will be lost. Another method is to slide the glass over the foil, without the assistance of paper. The methods of silvering glass globes, and the convex sides of meniscus glasses for mirrors, are seldom practised, except by very experienced workmen. SIMARONA, a name given by the Spaniards in America to the bastard vanilla. - SIMAROUBA, the bark of the roots of a tree, first imported into Europe in the year 1713. It has since been ascertained to be a species of the quassia, and has been found exceedingly serviceable in many disorders. SIMIA, the Ape, in Natural History, a genus of Mammalia, of the order Primates. Animals of this genus are commonly divided into such as have no tails; such as have only very short ones; such as have very long ones; and lastly, such as have prehensile tails, with which they can lay hold of any object at pleasure. These four classes are called respectively apes, baboons, monkeys, and japajous. In the whole genus there are enumerated by Gmelin sixty-three species, of which we shall notice some of the most important.—S. satyrus, or the ourang-outang, grows, in its native woods of Africa and India, to the height of six feet, and subsists, like most other species, on fruits. It flies from the haunts of mankind, leads a solitary life, and displays great strength, agility, and swiftness, which render it extremely difficult to be taken. It has been known to attack and destroy negroes wandering at a distance from their habitations, and to carry off women to its wretched habi- tation, watching them with such extraordinary vigilance, as scarcely to admit the possibility of their escape. Its general resemblance to the human figure and countenance is particu- larly and mortifyingly strong ; yet minute observation and dissection have pointed almost innumerable differences, the detail of which is here impossible. It is capable of being tamed and domesticated, and many years one was exhibited in London, which had been disciplined to sit, and work, and eat, like a human being, using a knife and fork for the latter purpose. Its disposition was pensive ; its manners were gentle; and it ap- peared to possess, for its keepers, and those to whom it had been long familiarized, a high degree of genuine gratitude and attachment.—The Barbary ape, is about four feet in height, and is the species: most commonly exhibited in public shows, and is trained to the performance of a great variety of tricks, calculated to attract popular admiration. The discipline it passes through is often severe, and this species is considered, in its natural state, as being more ferocious, and less sagacious, than several others of the class. It undergoes accordingly much cruel usage.—The great baboon, is between three and four feet high, of a gray-brown colour, and is particularly mus- cular in the upper part of its body; its hands and feet have sharp nails, like claws; but on its thumbs there are nails formed like those on the human fingers. It is an animal incapable of domestication.—The dog-faced baboon, is very large, and often greater than the common baboon. It is distinguished by a vast quantity of hair, spreading from each side of the head down the shoulders, and covering the animal to the waist, like a mantle.— The proboscis monkey, is one of the most curious in its aspect, and most ludicrous of the class. It is about two feet in length.- The preacher monkey, is as large as a fox, and is extremely common in the woods of Brasil. Travellers have stated, that it is usual for one of these to ascend a tree, and, by certain sounds, to collect vast multitudes beneath him, when he com- mences a howl so loud as to be heard to a vast distance,—The royal monkey, is about the size of a squirrel, and inhabits the S I N S I R. DICTIONARY OF MECHANICAL SCIENCE. 941 damp, woody districts of Cayenne, being never found on the mountains. In its sounds and manners it resembles the last species. SIMILAR, a composition made of red copper and zinc, in such proportions as to imitate the colour of gold. SIMI LAR Figures, in Geometry, such as have their angles respectively equal, and the sides about the equal angles pro- portional. SIMILE, in Rhetoric, is a comparison of two things, which, tho’ unlike in other respects, yet agree in the one pointed ont. SIMILITUDE, a striking resemblance between things, which conceals for a time the distinctive marks of individual identity. SIMITAR, or Sci Mit AR, a crooked or falcated sword, hav- ing a convex edge. It is now rarely used. SIMONIANS, in Church History, a sect of ancient Chris- tians, so called from their founder Simon Magus, or the magician. The heresies of Simon Magus were principally his pretending to to be the great power of God, and thinking that the gifts of the Holy Spirit were venal. - SIMONY, is the corrupt presentation of any one to an eccle- siastical benefice, for money, gift, reward, or benefit; it was not an offence punishable criminally at the common law, it being thought sufficient to leave the clerk to ecclesiastical censures. But as these did not aſlect the simoniacal patron, none were efficacious enough to repel the notorious practice of the thing. Several acts of parliament have, therefore, been made to re- strain it, by means of civil forfeitures, which that modern pre- vailing usage with regard to spiritual preferments calls aloud to put in execution. By one of the canons of 1603, every person, before his admission to any ecclesiastical promotion, shall, be- fore the ordinary, take an oath, that he hath made no simoni- acal contract, promise, or payment, directly or indirectly, by himself or any other, for the obtaining of the said promotion; and that he will not afterwards perform or satisfy any such kind of payment, contract, or promise by any other without his know- ledge or consent. To purchase a presentation, the living being actually vacant, is open and notorious simony; this being ex- pressly in the face of the statute. But the sale of an advow- son during a vacancy is not within the statute of Simony, as the sale of the next presentation is ; but it is void by the common law. A bond of resignation is a bond given by the person intended to be presented to a benefice, with condition to resign the same ; and is special or general. The condition of a spe- cial one is to resign the benefice in favour of some certain per- son, as a son, a kinsman, or friend of the patron, when he shall be capable of taking the same. By a general bond, the incum- bent is bound to resign, on the request of the patron. A bond with condition to resign within three months, after being re- quesied, to the intent that the patron might present his son when he should be capable, was held good : and the judgment was aſſirmed in the exchequer-chamber; for that a man may, without any colour of simony, bind himself for good reasons ; as if he take a second benefice, or if he be non-resident, or that the patron present his son, to resign; but if the condition had been to let the patron have a lease of the glebe or tithes, or to pay a sum of money, it had been simoniacal. SIMOOM. A wind or haze observed by Bruce in the course of his travels to discover the sources of the Nile, which is sup- posed to be in some respects analogous to the sirocco. It is call- ed by Mr. Bruce the simoom ; and from its effects upon the lungs, we can entertain but little doubt that it consists chiefly of corbonic acid gas in a very dense state, and perhaps mixed with some other noxious exhalations. SIMPLE, in Music, a term applied to that counterpoint in which note is set against note, and which is called simple, in opposition to the more elaborate composition, known by the name of figurative counterpoint. • SIMSON, Robert, a celebrated mathematician, born in the county of Lanark, and cducated at Glasgow. He died at the age of eighty-one. SIN, in Theology, a want of conformity to the will of God, which comprehends sins of omission and sins of commission. Sins are distinguished by the terms original and actual; the former is the morally contaminated nature we derive from our primary progenitors, and the latter arises from our personal disobedience. 99- 100, SINAPIS, MUSTAR D, a genus of plants belonging to the class of tetradynamia, and to the order of siliquosa, and in the natu- ral system ranged under the 39th order siliquosa. S1 NAPIs, in Gardening, contains plants of the hardy, her- baceous, annual kind, of which species those most cultivated are, the white and black mustard. -- SINCERITY, in Ethics, that excellent habitude and temper of mind which gives to virtue its reality, and makes it to be in reality what it appears. SINE, or Right Sine of an Arch, in Trigonometry, is a right line drawn from one end of that arch, perpendicular to the radius drawn to the other end of the arch; being always equal to half the chord, or twice the arch. SI NECURE, is where a rector of a parish has a vicar under him endowed and charged with the cure, so that the rector is not obliged either to do duty or residence. SI N E I) l E, in Law, a phrase which signifies, that judgment being given for the defendant, he is dismissed the court. The phrase is also used in parliament when a debate is adjourned, and no day ſixed for its resumption. This is considered as a polite way of dismissing it altogether. SI NEW, in Anatomy, properly denotes what is called a nerve, though, in common speech, it more generally signifies a tendon. The Jews will not eat the sinew of the thigh of any animal, in memory of the sinew of Jacob’s thigh, which was touched by an angcl. - SING ING, the art of making divers inflexions of the voice, agreeable to the ear, and corresponding to the notes of a song, or piece of melody. - SINKING FUND, a portion of the public revenue set apart to be applied to the reduction or discharge of the public debts. The appropriation of a part of the revenue to this purpose is a measure which had been adopted in other countries, long before any necessity for it existed in England; a provision of this kind having been established in Holland in 1655, and in the ecclesi- siastical state in 1685. SINUOSITY, a series of bends, curves, or other irregular turns and figures ; sometimes rising, sometimes sinking, such as is described by the motions and contortions of serpents, the windings of rivers, and the indentations and projections of the Sea-COast. SIPHENIA, in Botany, a tree from which issues a resinous exudation so well known under the appellations of caoutchouc, elastic gum, and Indian rubber. For the manner in which Indian rubber is made, see CAOUTCHOUC. SIPHON, or SYPHoN, in Hydraulics, a bended pipe having the air sucked out of it, and, with one end placed in a vessel containing any liquid, is used to draw off the liquor at the other. SIPHURIUS LA Pis, a steatite substance, found in the island Siphnos, in the AEgean sea, and dug up in large masses near the coast. This substance being soft when found, was easily wrought into various kinds of vessels, which, being burnt and oiled, became black, solid, susceptible of a fine polish, and capable of enduring a great degree of heat. Under the name of Lapis Lebitum, the same substance is still known in many parts of Europe. In its native state, it is said to resemble the Soap rock. - SIPONCULUS, or TUBE-WoRM, a genus of insects of the order vermes intestina; the generic character is, body round, elongated; mouth cylindrical at the end, and narrower than the body ; aperture at the size of the body, and Veruciform. SIREN, in fabulous history, the Mermaid; and sometimes the term is applied to imaginary sea nymphs, or sea sorceresses, who allure mariners to their fate. SIREN, in Natural History, a genus of Amphibia, of the or- der reptiles, or of the order meantes, an order instituted by Linnaeus on account of this genus of animals alone. The eel- siren is most nearly allied to the lizard tribe, but diſſers from it in having only two feet, and those armed with claws; the body is shaped like an eel; its colour is a dark brown speckled with white; it is often more than two feet long, and inhabits the stagnant waters of South Carolina; sometimes, however, quit- ting water for the land. The anguine siren, is a native of a particular lake in Carniola, from which the water regularly drains off during the summer ; during which time the bottom produccs corn or pasture. In ll G. 942 S K I S L E. DICTIONARY OF MECHANICAL SCIENCE. In autumn the water returns with considerable rapidity, flowing principally from springs in the neighbouring fountains. In this lake this siren is found of the length of cleven inches, and of a pale rose colour. It has both fore and hind legs. Its move- ments are extremely slow and weak when it is placed in a ves- sel, either with or without water; but in its native situation it is far more active It is by some supposed to be the larva of a lizard, and by others imagined to be a complete animal. Its habits are predatory, and it subsists on the smaller inhabitants of the water. - - SIRI, among the Romans, were subterraneous vaults or caves, in which wheat could be kept sound and fresh for fifty CarS. SIRIUS, in Astronomy, the dog-star in the constellation of Canis Major, south-east of Orion. It is the most brilliant star that appears in the heavens, and is therefore thought to be nearer to us than any other. See OR1ON. SIROC, or SIRocco, a periodical wind which visits Italy, Dalmatia, and Sicily about Easter. It is attended with such a strong degree of heat, that at Palermo it has been compared to a blast of burning steam, issuing from the mouth of a hot oven. It rarely continues at one visit more than forty hours, but during this time, the inhabitants remain within their houses, otherwise life would be scarcely supportable. Its effects are debilitating, but it has not been accused of generating any particular disease. SITE, or Scite, denotes the situation of a house, messuage, mansion, village, or town, and not unfrequently the ground on which either is supposed to stand. . SKATE, a sort of shoe armed with a strong rib of steel, for sliding on the ice. The exercise of skating, carried to a certain degree of perfection, surpasses all other pastimes, in the beauty of its movements, and the variety and rapidity of its graceful attitudes. The dexterity with which an experienced skater will pass through his numerous and intricate evolutions is truly astonishing; and to those who are not intimately acquainted with the laws of gravitation, his surprising agility has all the appearance of enchantment. To those who begin when young, under the tuition of an experienced skater, thc exercise is learned with great facility. It cannot, however, be denied, that it is frequently attended with danger, for scarcely a winter passes in which, through the breaking of the ice, several lives are not lost. Some skaters have been known to travel fifteen miles an hour. SKEET, a sort of long scoop used to wet the sides of a ship, in order to keep them cool, and prevent them from splitting by the heat of the sun. It is also employed in small vessels, to wet the sails, to render them more efficacious in light breezes: this operation is sometimes performed in large ships by means. of the fire-engine. * SKELETON, all the bones of a dead animal, dried, cleansed, and disposed in their natural situation. SICIDS, or Skeeds, long compassing pieces of timber, formed to answer the vertical curve of a ship's side. They are notched below, so as to fit closely upon the wales, and extend from the main-wale to the gunnel, being strongly nailed to the side. Their use is to preserve the plank of the side when any weighty body is hoisted or lowered against it. SKIFF, a small light boat, resembling a yawl; also a wherry without masts or sails, usually employed to pass a river. SKIM Coulter, in Agriculture, a sort of coulter invented by Mr. Ducket, for paring off the surface of coarse grass or other lands, and placing it in the bottom of the furrow, so as to be fully covered and secured. This coulter is connected with the plough that turns the furrow. Ski Mi Milk, that sort of milk which is left after the cream has been taken off its surface. Ski M. Milk Cheese, an inferior kind of cheese made from skim- med milk. SKIN, in Anatomy, a large thick membrane spread over the whole body, serving as an external organ of feeling, and as an ornament and covering to the parts beneath. - Ski N, in rural economy, is the hide of any animal, and is applied to numerous purposes besides its principal one, that of being made into leather. SKIRMISH, in War, an irregular kind of combat between small parties in sight of their respective armies. These com. batants are sometimes directed thus to advance, and commence. an encounter, in order to bring on a general engagement. SKULL, that part of the head which forms its great bony cavity. - SKY, the blue cxpanse with which the globe is encircled. The azure colour of the sky Sir Isaac Newton attributes to vapours beginning to condense therein, which have consistence cnough to reflect the more violent rays, but not enough to reflect the loss reflexible ones. - SKY Scrapers, small triangular sails, sometimes set above the royals; they arc, however, very rarely used. - SLAB, an outside sappy plank or board sawed off from the sides of a timber tree: the word is also used for a ſlat piece of marble. SLA B Limes, small cords passing up behind a ship’s main-sail or fore-sail, and being reeved through blocks attached to the lower part of the yard, are thence transmitted each in two. branches to the foot of the sail, where they are fastened. They are used to truss up the sail, but more particularly for the con- venience of the steersman, that he may look forward beneath it. SLACK OF A RoPE, that part which hangs loose, as having no strain or stress upon it. Slack Rigging, implies that the shrouds, stays, &c. are not so firmly extended as they ought to be. Slack in Stays, signifies slow in going about. Slack Water, the intervals between the flux and reflux of the tide, or that time during which the water apparently remains in a state of rest. SLAG, denotes vitrified cinders. In some places it is used in buildings, and in repairing roads. - SLAKE, the saturating of quicklime with water, or other moisture. SLAKED LiMe, such as is reduced to a state of powder by the action of water upon it, or the hydrate of lime. In this case the lime is combined with about one-third of its weight o. Water. SLAKEN, in Metallurgy, a term used by smelters to ex- press a spongy semivitrified substance, which they mix with ores of metal to prevent their fusion. It is the scoria, or scum, separated from the surface of a former fusion of metals. SLAM, the refuse of alum works, which is used as a manure, mixed with sea-weed and lime, in Yorkshire. SLAP-DASH, in Building, provincially rough casting. It is a composition of lime and coarse sand reduced to a liquid state, and applied to the exterior of walls, as a coating that is both preservative and ornamental. SLATCH, the period of a transitory breeze, or the length o. its duration. SLATE, a well-known, neat, convenient, and durable material for the covering of the roofs of buildings. There are great va- rieties of this substance, and it likewise differs very greatly in its qualities and colours. - In some places it is found in thick. lamina, or flakes, while in others it is thin and light. The co- lours are white, brown, and blue. It is so durable in some cases as to have been known to continue sound and good for centuries. SLAVES and SLAVERY. Slavery, in its proper and detest- able signification, is a system which gives to the master an ab- solute power over the destiny and life of the slave. By the laws of England, and the uncorrupted feelings of Englishmen, it is held in the utmost abhorrence; nor is it suffered to pollute our atmosphere or soil. The instant a slave puts his foot on British ground, the laws take him under their protection, and he is declared free. Yet, unhappily, it still continues in our West India islands, to the disgrace of the British name; and in other countries, to the lasting reproach and dishonour of human nature. * SLEAZY Holl AND, a slight Holland, thus called because made in Silesia, in Germany. The texture being thin, alſ slight, ill-woven Hollands have obtained the name of sleasy. SLEDGE, a kind of carriage without wheels, for the convey- ance of very weighty things, as huge stones, &c. SLEEP, in Physiology, the greater or less suspension of the functions of sensation and volition. The phenomenon of sleep has given rise to many curious speculations, inquiries, and theories; but its real nature is better known from fact and experience, than from any philosophical investigations. S L I S L I 943 DICTIONARY OF MECHANICAL SCIENCE. SLEEPERS, in a Ship, timbers lying before and aft, in the bottom of the ship, as the rung-heads do; the lowermost of them is bolted to the rung-heads, and the uppermost to the futtocks and rungs. Sleepers, a name given to some animals that sleep during the winter, such as bears, marmots, dormice, bats, hedge- hogs, &c. Sleep ERs, in the glass manufactories, are large iron bars crossing the smaller ones, and hindering the passage of the coals, but leaving room for the ashes to descend. SLee PERs, among Carpenters, are pieces of wood to support joists, also a name formerly given by shipwrights to the thick stuff placed longitudinally in a ship's hold, opposite to the several scarfs of the timbers, but now generally applied to the knees which connect the transoms to the after timbers on the ship's quarter. They are particularly used in Greenland ships, to strengthen the bow and stern-frame, to enable them to resist the shocks of the ice. - SLICH, the ore of any metal, particularly of gold, when it has been pounded and prepared for further working. SLIDE-BUTT, in Agriculture, a sort of sledge in the form of a strong oblong box, shod underneath with thick pieces of timber. It is chiefly used for drawing manure from place to place, but chiefly in fields. It will contain about three wheel. barrows’ full. Sometimes the butt has wheels, and when this is the case it is called gurry. SLIDING, in Mechanics, is when the same point of a body, moving along a surface, describes a line without revolving. SLIME, a soft muddy substance left by tides and other waters, in different places, which, mixed with other materials, become an useful manure. , SLING, an instrument serving for casting stones with great violence. The inhabitants of the Balearic islands were famous in antiquity for the dexterous management of the sling; it is said they bore three kinds of slings, some longer, others shorter, which they used according as their enemies were nearer or more. remote. It is added that the first served them for a head-band. the second for a girdle, and that a third they constantly carried with them in hand. - -- SLINGING, is used variously at sea, but chiefly for the hoisting up casks, or other heavy things, with slings. SLINGS, a rope fitted to encircle a cask, jar, bale, or case, and suspend it while hoisting and lowering. Of these there are various sorts, according to the weight or figure of the object to which they are applied. Slings of a Yard, ropes fixed round its middle, and serving to suspend it for the greater ease of work- ing, or for security in an engagement; in the latter case they usually add iron chains to the slings of the lower yards. This term also implies the middle, or that part of the yard on which the slings are placed. Boat-Slings, strong ropes, furnished with hooks and iron thimbles, whereby to hook the tackles, in order to hoist the boats in or out of the ship, the hooks of the slings being applied to ring-bolts fixed in the keel and extremi- ties of the boat. Butt-Slings, are those used in lading and deli- vering ships, and are nearly in the form of a pair of spectacles. SLIP, a place lying with a gradual descent on the banks of a river, or harbour, convenient for ship-building. Ship SLIP, Morton's Patent for Hauling Wessels out of the Water for Repairs, 3 c.—A carriage is constructed, as repre- sented in the plan, p. 944, with truck-wheels to run upon the iron railways of the inclined plane, these truck-wheels having ſlanges to guide them. Blocks are laid upon the keel-beam of the carriage, to a sufficient height, so that the keel of the vessel clears the ends of the cross pieces ; and each block embraces four trucks—two on each side of the beam. The blocks which slide npon the cross pieces, are made up to correspond to the rising of the vessel’s bottom. These blocks are run out to the extremity of the cross pieces, and their ropes, crossing the car- riage, are reeved through a sbeave attached to the opposite cross piece, up to the top of the rope rod. The shores (if any are necessary) are put into their places, turn upon a joint at their heel, and are secured (while the vessel is floating on,) from falling outwards by a small chain. The carriage, thus prepared, is let down the inclined plane generally at low water, but if found expedient, into the water, (as the weight of the metal attached thereto keeps it down in its place,) sufficiently far to allow the vessel to float upon it. The chain-purchase is attached to the carriage: and a water-staff is placed at the fore-end of the keel-beam, to mark the depth of water, and be a guide in floating the vessel on. The vessel is brought to the end of the carriage, and hauled over it, (having bow and quarter lines to steady her,) till her fore-foot, or advanced part of the keel, takes the blocks between the fore-foot guides. The ends of the sliding block-ropes are now taken from the rods on board, but kept slack; she is still hauled forward as the water flows, until the keel takes the blocks at the contracted part of the guides, which are just wide enough to receive it. Being still afloat abaft, having been previously so trimmed,) the vessel is then adjusted over the blocks abaft by the water line. When the iron guides are hauled up, they will confine her to settle down truly. By heaving the parchase, she will soon take the blocks abaft, which is observed by the water-mark left on her bottom ; she is trimmed upright, and the foremost bilge, or sliding-blocks, hauled in tight. As she rises out of the water, each succeeding block is hauled in, but not till the weight of the vessel has settled well on her keel. The sliding-blocks are prevented from springing back, by their palls falling into their racks; the shores are brought to her sides, and cleared. When thus secured, she is hauled up the inclined plane, at the rate of from 2% to 5 feet per minute, by six men to every hundred tons. Being hauled up, she is shored from the ground; the keel-beam is secured from moving ; and the sliding-blocks, with their cross pieces, are in a few minutes removed, when the vessel is ready to be repaired. The blocks being relieved of the vessel in the usual manner, the keel beam, with the after cross beam, will run from under her. The carriage is again put together, and another vessel can be hauled up astern of the former. When a vessel is to be launched, the cross pieces, with their blocks, are put under her, and instantly let into the water ; or, to launch and haul up vessels the same tide, temporary blocks are put under the bottom of the vessel to be launched upon the cross pieces, instead of the sliding blocks, which are prepared as before, to suit the bottom of the vessel to be taken up ; the vessel is launched; when she, and the temporary blocks which steadied her, float from the carriage, and the other vessel is taken on, and hauled up as formerly. Advantages of this Invention.—1st. The vessel being above ground, the air has a free circulation to her bottom, thereby requiring no firing ; the men work with much more comfort, of course quicker, and in winter, particularly, they have light bet- ter and much longer, than within the walls of a dry dock; con- siderable time is also saved in carrying and removing the ma- terials for repairing the vessel. 2nd. Such is the facility of its operation, that ships can be hauled up, inspected, and even get a trifling repair, and be launched the same tide; and the process of repairing one ves- se: is never interrupted by hauling on another, as is the case in dry docks, from the necessity of letting in the water. 3d. The vessel is hauled up the inclined plane at the rate of 2} to five feet per minute, by six men to every hundred tons ; so that the expense of hauling up and launching a vessel from 200 to 300 tons, does not exceed thirty shillings 4th. A slip can be constructed at about one-tenth the expense of a dry dock, and be laid down in situations where it is impossible to have a dock built. 4th. There is no previous preparation, or ſitting bilge-ways, necessary. The chain of the mechanical power is attached solely to the carriage on which the vessel is floated ; therefore the vessel is exposed to no strain. The whole apparatus can be removed from one place to another, and be carried on ship-board. Description of the Drawings, A, A, A, A, side beams of the car- riage, with trucks or rollers beneath, at each cross piece; B B, B, B, sideway; c, c, e, c, c, c, c, cross pieces; c', c', cross-pieces, which racks; cºc", aftermost cross pieces; b, b, braces, 9, 9, iron guides; b', b', oblique braces; g’, g’, guides to receive the fore-foot of the vessel ; s,s, s, s, s, s, s, s, s, s, sliding blocks; r, sliding-block rope; s’, s', shore; ", r', rope for hauling guide or crutch, M, midway, with rack; N, N, main or keel beam of the carriage; P, purchase; W, wheel or pinion, capstan, or other purchase; S, large stones; C, chain; K, keel of the vessel; G, guide for the after-part of the keel; p, rack-pall; R, R, inclined 944 S L. O. S L U DICTION ARY OF MECHANICAL SCIENCE. . plane, road, or platform, laid nearly with the same slope as the Fºzz J& jº .----~~~ ‘. . ." | > | * ; M "X N | #e || ||s |||s N ||\ \ J. f. ºr tº ſº - - }|llll-llº ! $º : [] & © We S. º 2. a! * .5% ºf A # i: Fºº ##### 㺠ºšŠē _º N º and carriage. Fig. 2, side view of the ship. Fig. 3, stern view. Fig. 4, head view. . At Stobcross, a little below the new Quay on the Clyde, at Glascow, there is a slip on Morton’s principle, but differing a little in the application. The vessel is there made to rest on the bilge, or under part of the bottom, instead of the keel, as in the above plan; by this means she requires less water to raise her on the carriage, as the groove between the iron rail-ways admits the keel, and allows it to move up and down freely, without requiring any support. The carriage consists of two separate beams resting on the rail-ways, without any inter- mediate keel-beam or cross pieces to connect them ; to the ends of both are attached two connected series of iron rods, and two chains by which they are drawn up the inclined plane. SEIPS, in Gardening, such portions of plants as are slipped off from their parent stems for planting out as sets. SLOATH, or Sloth, the name of an animal remarkable for the slowness of its motion, whence its appellation. Of this animal there are three species. It is about the size of a fox, and is a native of South America, and of Ceylon in India. It requires three or four days to ascend a tree and descend from it ; and on level ground, about fifty paces is a day's journey : its food is fruit, and the leaves of trees. SLOE, Prunus Sylvestris, the English name for the wild plum. The juice expressed from this fruit while unripe, and inspis- sated by a gentle heat to dryness, is called German acacia. The bark both of the branches and roots, in intermittent fevers, is said to be little inferior to the Peruvian bark. The ſlowers made into a syrup and sweetened with sugar, is a good purgative for children. Tea is frequently adulterated with the leaves. SLOOP, in Naval affairs, a small vessel furnished with one mast, the main-sail of which is attached to a gaff above, to the mast on its foremost edge, and to a boom below ; it differs from a cutter by having a fixed steering bow-sprit, and a jib-stay; the sails also are less in proportion to the size of the vessel. Sloops of war are vessels commanded by officers of a middle rank between a lieutenant and a post-captain; these are styled masters and commanders. They carry from ten to eighteen guns, and are variously rigged, as ships, brigs, schooners, and sometimes cutters. SLOPS, a name given to clothes for seamen. SLOWWORM, a species of innoxious serpent, sometimes called the blind worm, and sometimes the deaf adder. SLUG, in Gardening, a destructive kind of snail, eating off the leaves and buds of tender plants. There are various kinds; but all are highly mischievous to the gardener and farmer. * SLUICE, in Hydraulics, a frame of timber, stone, earth, &c. serving to retain and raise the water of the sea, a river, &c. and on occasion to let it pass. - - SLUIce, SELF-ACTING, for Mills, or an Hydraulic Appa- ratus, for regulating the Supply of Water to Mills, by Mr. Robert Thom, of Rothesay Mills, near Glasgow.”—The drawings, in the Plate, exhibit no less than five distinct and separate operations; that is, each figure in the drawing is a complete apparatus of it- self, applicable to different purposes, or under different circum- stances, from any of the other drawings. The apparaatus, fig. 10, which, on account of the variety of operations it has to perform, appears more complicated than any of the others, is, notwith- standing, very simple when executed on a large scale. The advantages derived from the adoption of these inventions are many; as they relieve us from all anxiety and care respecting the waste of water, and the damages done to banks and other grounds by its overflow; and the exact quantity of water re- quired by the works is always sent down, and no more; two steam-engines of thirty-horse power have been superseded at Edinburgh by their adoption; the yearly saving thereby is above six hundred pounds sterling. Explanation of the Plate.—The lever sluice, fig. 1. This sluice, when placed on a reservoir that supplies any canal, mill, or other work, with water, (where the aqueduct between the reservoir and such work is on a level,) will always open of its own accord, and let down the quantity of water wanted by such work, and no more ; that is, when water is wanted it will open, and when not wanted it will shut; so that it not only supersedes the water-man, but saves a great deal of water. A B, a tunnel through which the water passes from the dam to CD, the aque- duct that carries the water to the mills. E, a float that rises. and falls with the water in the aqueduct. F, an aperture in the mouth of the tunne. G, the self-acting sluice that opens and shuts aperture F. H I, a lever which turns upon fulcrum K, and is connected at one end with sluice G, and at the other with float E. The sluice G is here represented open, as when the mills are going, but when the sluice is shut that lets the water on the mili wheel, the water in the aqueduct rises, and with it float E, which raises the end I, and lowers the end H of the lever H I, and shuts sluice G. When the water is again let upon the wheel, the surface of the aqueduct falls, and with it the float, which opens sluice G as before. Upon the lever H I there is another small lever LM, which turns upon fulcrum M, and has the weight N suspended to the other end L. In the ordinary working of the apparatus this lever is quite stationary, and produces no effect whatever; but during floods, the aque- duct is swelled by streams that run into it between the reservoir and the mills, and when this happens when the mills are not at work, the water, by pressing up one end of the lever when the other cannot get down, would strain or break the apparatus. But, in such cases, the extra pressure raises the small lever, which takes all strain off the other parts; that is, the weight M requires more force to lift it than is required to shut the sluice; and therefore will not move till that takes place: but when the extra strain is continued after the sluice is shut, the lever and weight then rise with the float. The dimensions of the float are nineteen feet square by seven inches deep; the lever is twenty- seven feet long, being twice the length between the fulcrum and the sluice, that it is between the fulcrum and the float. The sluice is three feet three inches long, and fifteen inches deep ; but it requires to be raised only seven inches (when the water in front is three feet high) to pass as much water as gives a power of forty horses to a water wheel, the fall there being twenty feet. To determine the proper dimensions of the float and relative lengths of the ends of the lever, it was necessary to ascertain how far the sluice required to be raised, to pass the quantity of water wanted; and also how far the water in the aqueduet might be raised above the height required to supply the works: the first was found to be seven inches, and the last only four inches. The end of the lever connected with * From the Transactions of the Society of Arts, &c. vol. xl.-The Society presented their large Silver Medal to Mr. Thom for this commu- nication. - z. 94% ºz. IT-TI-№ · „22?«%，�� º //w/Ž�� «» · Erny- ðarvaement * - ~--~ •••• - - ---→→→→→→- Publishedby Fisher. Son & Cº Caxton , London. Dec.36, 1526. Āež;& sc. S L U S L U DICTIONARY OF MECHANICAL SCIENCE. 945 the float was made, therefore, only half the length of the end connected with the sluice ; and the float was made of such di- mensions, that, when sunk half an inch in water, the weight of water thereby displaced was equal to twice the weight required to shut the sluice with an equal lever. When, therefore, the water in the aqueduct rises upon the float half an inch higher than it sinks by its own weight, the sluice begins to move ; and by the time the water rises other three and a half inches, the sluice is of course seven inches down, or shut. This apparatus has now been working at Rothesay five years. - The water sluice, fig. 2. This sluice, when placed upon any river, canal, reservoir, or collection of water, prevents the water within from rising above the height we choose to assign to it; for whenever it rises to that height, the sluice opens, and passes the extra water; and whenever that extra water is passed, it shuts again; so that whilst it saves the banks at all times from damage by overflow, it never wastes any water we wish to retain. A B part of a canal, river, stream, or collection of water. C D high water mark, or the greatest height to which the water is allowed to rise. EF a sluice, or folding- dam, which turns on pivots at F. G. a hollow cylinder, having a small aperture in its bottom, from which proceeds the pipe H I. K another cylinder, water-proof, that moves up and down within the former cylinder. L. a pulley, over which passes a chain attached to the sluice and to the cylinder K. When the water in the canal or river rises to the line C D, it passes into cylinder G at the small holes M. M., and this lessens the weight of cylinder K so much, that the pressure of the water in front of sluice EF throws it open. When the water subsides, and no longer runs in at the small holes in cylinder G, that cylinder is emptied by the small pipe H I at its bottom, which is always open, and then the weight of cylinder K shuts the sluice as before. An apparatus of this kind was first erected at Rothesay in 1817. The dimensions of one of these are, K, two feet diameter and two feet deep, over ali: weight 500 lbs. G, five feet ten inches deep and two feet one inch diameter inside. E F, four feet long and two feet deep, but the cylin- ders are powerful enough to work the sluice six inches deeper. This sluice may be made with pivots to turn at the top, bottom, or middle : it may also be placed at the surface or bottom of the water, or any intermediate space, or right below, as suits the particular case ; the cylinders may also be placed as shewn in fig. 3, without the reservoir; that is, on the outside, or be- hind the dam or embankment, by having a pipe N N to com- municate between the upper part of the canal or reservoir and the cylinder. In this case, the chain passes over two pulleys, and is attached to an arm projecting from the back of the sluice. By adopting this principle, a self-acting dam may be raised in any river or stream, up to high-water mark, by which means a considerable reservoir will be obtained, whilst during floods the dam will fold down, and no new ground be over- flowed. In lawns or pleasure-grounds, through which streams or rivulets flow, these sluices might be applied to advantage; for, by placing one on the bank of each pond, the water within would always be kept at the same height, let the weather be wet or dry; and, therefore, flowers and shrubs might be planted close to the water’s edge, or in it, as best suits their respective habits, and their position with regard to water would always be the same. + The double-valve sluice, fig. 4. This sluice answers the same end as the lever sluice, but is more applicable in cases where the reservoir is deep, and the embankment consequently large. It also answers the purpose of the waster sluice, as it opens and passes the extra water, whenever it rises in the reservoir the least above the height assigned, and of course supersedes a by-waste. In making hydraulic experiments, this sluice will also be found of considerable importance, as, by keeping the cistern from which we draw the water for the experiments always exactly at the same height, it will not only save intri- cate calculations, but make the result on the whole more correct. A, part of the tunnel through which the water flows from the reservoir to B C, the aqueduct that conveys the water to the mills. D E a sluice that turns upon pivots at D. F.G. a hollow cylinder; H another cylinder, water-proof, of rather less spe- cific gravity than water, and which moves up and down freely in cyliuder F G: a chain, one end of which is fixed to an arm 99- 100, empties itself, and the weight H closes the sluice. attached to sluice D E, and the other to cylinder H, passes over pulleys I and K ; L a cistern always full of water, being sup- plied by a spring; G M a pipe that communicates between cistern L and cylinder FG ; N O the required level of the water in aqueduct B C ; P a float which rises and falls with the water in aqueduct B C : attached to this float is a spindle car- rying two valves, which by the descent of the float close the aperture in the lower end of pipe M, and open the communi- cation between M and the cistern L. When the float P, and consequently the attached valves, rise, indicating a sufficiency of water in B C, the water escapes from the cylinder F G, be- cause the lower aperture in M is opened, and the upper, which communicates immediately with the cistern L, is closed ; as shewn on a larger scale, fig. 6. The sluice DE, fig. 4, is repre- sented shut, cylinder FG empty, cylinder H at the bottom of FG, and the water in the aqueduct at its greatest height. Sup- pose now, water to be drawn from the aqueduct for any purpose, the float P will fall with the water, and with it the valves. The water now flowing into FG from L will be retained ; H will be deprived of its weight, and consequently of its action on sluice D E, which will then yield to the pressure of the water in the reservoir, and pass the requisite quantity, till the float P rising to its former level, opens the lower valve, and shuts off the communication between L and M ; , the cylinder F G then In order to make this sluice operate also as a waster sluice, a tube is made to communicate between the reservoir and cylinder FG ; this tube, which must necessarily supply water to FG faster than it can escape by the valve in the lower end of M, enters the reser- voir at the height to which we wish to limit the rise of the water, and whenever it rises so as to flow into this tube, the cylinder FG is filled, and the sluice DE opens, and passes the extra water so long as the stºpply continues through the tube to the cylinder FG"; when that ceases by the subsiding of the water in the reservoir to its limited height, the sluice DE shuts as before. The axis of motion of this sluice, instead of being placed at the top, may be placed a little above its centre of pressure, as shewn in fig. 7. In this case, the whole of the operations before described will be reversed: the weight of cylinder H will tend to open the sluice, and the pressure of water in the reservoir to shut it; the rise of the float P, instead Gf opening the lower aperture of M, will close it, and open the communication with the cistern L, as shewn in fig. 8, the con- sequence will be, that the cylinder H will be deprived of its weight, and the sluice will be closed by the pressure of the water in the reservoir. In this case, the axis of motion is placed just so far above its centre of pressure as to allow the extra pressure below to overcome the friction, and shut the sluice when cylinder H is floated: this cylinder need only be heavy enough to overcome twice the friction, in order to open the sluice when the water is drawn from cylinder FG ; I have found the friction in this case to be less than one-fiftieth of the weight of the column of water pressing upon the sluice; but to guard against contingencies, the machine is made powerful enough to act, although the friction were to become one-tenth, which from the nature of things is more than it can ever be. An apparatus on this construction was erected at Rothesay, in 1819, and has been in constant use ever since. - The single-valve sluice, fig. 9. The construction of this sluice is nearly the same as the last, only it is applicable in cases where the reservoir is on high grounds above the works re- quiring the water; and where, of course, the water passes down a declivity. A B part of the tunnel of a reservoir; CD a sluice that turns upon pivots at C ; EF the rivulet that carries the water from the reservoir down to GH, part of a level canal or aqueduct. I is a hollow cylinder; K another cylinder, water- proof, of rather less specific gravity than water, which moves freely up and down within cylinder I; L a pulley, over which passes a chain attached at one end to the sluice, and at the other to the cylinder K; M., a small cistern kept always full of water, either by a small hole below the sluice, or by the waste from the sluice; a small pipe communicates between this cis- term and the upper part of cylinder I; N O, another small pipe, communicating under ground between cylinder I and a valve at the lower end of O, which is closed by the descent of the float P; the float is placed within a small pool of water on the same 11 H g”, 946 $ L. Ü level as, and communicating with, the canal. The water in the canal is represented as at its greatest height, the valve opened by the float P, the cylinder I empty, because the valve at O passes the water faster than it is supplied from the cistern M: the cylinder K is consequently at the bottom of I, and the sluice is closed. When the surface of the water falls in the canal, the float P falls with it, the valve at O is closed, the cylinder I is filled, and K floated, the sluice CD opens by the pressure in the reservoir, and supplies water till the canal G. H. acquires its proper height. varied, as in the last instance, by hanging the sluice on pivots a little above the centre of pressure, so that it shall be kept closed by the weight of the water in the reservoir, and opened by the descent of cylinder K; the valve at O will then require to be shut by the ascent of the float P. It is of no consequence, therefore, in regard to regulating the supply of water, how far the reservoir is from, or how high above, the level of the works requiring the water, save that the length of the pipe N O must correspond with the distance, and its strength with the height or pressure of the water; it is necessary, however, that the bore of this pipe should be small, particularly where its length is considerable, in order that the sluice may open or shut in a short time after the valve at O opens or shuts, and at the same time require only a small supply of water for cistern M, as that supply must always flow, whether it be otherwise needed or not. Suppose, therefore, the opening into pipe N O from I to be only half an inch bore, and that the valve at O is shut, it is evident when that pipe is empty, that the sluice CD will not open (or shut, if being on pivots placed just above the centre of pressure) till both the pipe N O and cylinder I be filled; and that the smaller the bore of that pipe, the sooner will it be filled. The time, therefore, that sluice CD takes to open (or shut, as the case may be) after the valve at O shuts, will always be the same that the pipe N O and cylinder I take to fill; and to make sluice CD take an equal time to shut (or open, as the case may be) after the valve at O opens, the aperture of that valve must be such as to take an equal length of time to run off the water to the bottom of cylinder I, (while the water is still flow- ing from cistern M,) as the pipe from cistern M takes to fill both cylinder I and pipe N 0, when the valve at O is shut. The chain sluice. This apparatus answers exactly the same purpose as the last, but the construction is somewhat different; that difference is described by dotted lines in connexion with the last figure, of which let all the parts be supposed to romain except the pipe from the cistern M, the pipe N O, and the float P. A., pipe m communicates between cistern M and the upper end of cylinder no, from the lower end of which proceeds a pipe p connected with the bottom of cylinder I; an aperture in the lower extremity of no is supplied with a valve opening down- wards loaded with a weight q, and attached to a rod suspended from the end of a lever rs, moving on a fulcrum at t; a chain passing round two pulleys w and v connects the other end of this lever with a float w, of sufficient weight to overcome the loaded valve q. To apply this apparatus where the sluice is hung on pivots just above the centre of pressure, no change is required but that of making the valve q open upwards. This construction may, perhaps, be adopted with advantage on ac- count of its cheapness, where the reservoir is very near the level canal, but a considerable height above it; as a brass wire one-tenth of an inch diameter will be strong enough for the chain where the distance is short, it having in any case little more to lift than twice its own weight; the former method using the pipe NO instead of the chain, seems better adapted to ge- neral purposes. The double weather sluice, fig. 10. This apparatus is de- signed for what are generally called compensation reservoirs, where we are only allowed to retain the surplus water of floods, the rivulet or stream being allowed to flow at all other times the same as if no reservoir were there. The usual way of doing this, which may be understood by reference to fig. 5, is to cut an aqueduct, A F B, round the reservoir C, along which all the water of the stream is carried past the reservoir, except during floods, when a part runs over at the by-wash F into the reser. voir. . But before any part is thus allowed to run over, the proprietors below at Z must have all they need; and then the rise that sends part into the reservoir, sends also more down DICTIONARY OF MECHANICAL SCIENCE. The mode of producing this effect may be S L U. the aqueduct; this additional part sent down is therefore lost. But the same rains that swell the streams above the reservoir, also swell the streams GHI and K between the reservoir and place below at Z, where the greatest quantity of water may be needed ; all this additional water from the streams below, is therefore also lost. By adopting this apparatus, all that waste is saved, or retained in the reservoir; so that whilst the pro- prietors below have, in all ordinary times, the same water as if no reservoir had been made, we retain in the reservoir, during floods, all the water not then needed below. A is a basin of water, behind a reservoir, in which the water is always kept at the same level by the apparatus, fig. 4. B, one of a number of sluices of the same kind on that basin. C, a can, open at the top, and having a very small aperture in the bottom; a chain passes over pulley D, having one end fixed to the arm E, at- tached to sluice B, and the other to can C. F., a weight that keeps the sluice B always shut, when the can C is empty: when that can is full of water, it lifts the weight F, and opens the sluice. GH, a section of that part of the rivulet immediately before it falls into the reservoir. I KL, a pipe, which commu- nicates between the rivulet at G. H., and the can C. When the water in the rivulet G H is so low only as to flow through aper- ture 1, then, all that water passing down pipe IKL, flows out at M into can C, which "being thus filled with water, opens sluice B, and passes as much' water as the rivulet then brings into the reservoir. But when the rivulet swells so as to flow out at aperture 2, then the opening at M not being able to pass the whole, the water rises in pipe IK, and passes along pipe NOP, and falling into another can,” opens a second sluice, which, with the first, passes as much water as the rivulet then brings into the reservoir. When the water in the rivulet rises so as to flow out at aperture 3, it rises also in IK, and passing along pipe QRS, flows out at S into a third can, and opens a third sluice; and these three pass as much water as the rivulet then brings, and which is here supposed to be the greatest quantity wanted at the place Z, fig. 5. Suppose now the flood should still continue to increase; then the streams and surface water between the reservoir and Z will increase the rivulet at Z, as well as the higher streams increase it at GH; but there was previously enough of water at Z; when, therefore, the rivulet rises so as to flow out at aperture 4, the water will rise also in the vertical tubes M, P, and S, which are respectively surmounted with wide hollow cylinders, T, U, and V, contain- ing the water-pipe floats W, X, and Y. The water first rises to float W, which it lifts, and thereby shuts valve L: the water in can C then passes out at the small opening in its bottom, and the weight F shuts sluice B, which stops as much water in the reservoir as the streams below have increased. When the water rises in the rivulet so as to flow out at aperture 5, it rises also in the tubes till it lift float X, which shuts another sluice. When the rivulet rises till the water flows out at aperture 6, it raises float Y, and shuts the third or last sluice, the flood being now supposed so great, that the streams below the reservoir are sufficient for the supply at 2. When the streams begin to fall, the rivulet at G H will also fall, and when the water ceases to flow into aperture 6, the water falls so far in the tubes as to let down float Y, and open one sluice; when it ceases to flow out at aperture 5, the float X falls, and a second sluice opens: when it ceases to flow out at aperture 4, the third sluice opens, which, with the other two, passes all the water that the rivulet is then bringing into the reservoir. Should the rivulet continue to fall so as not to flow out at aperture 3, then the water ceases to flow along QR, and one sluice shuts; should it fall below aperture 2, the water also ceases to flow along NO, and a se- cond sluice shuts; should the rivulet become quite dry, then the third or last sluice shuts. Any number of sluices may be used, as found necessary: and in this way the same quantity of water will always run in the rivulet at Z, as if no reservoir had been placed in the rivulet above; except during floods, when all the water not needed at Z, would be retained in that reser- voir. Besides the immense quantity of water thus gained during floods, the expense of cutting an aqueduct round the * { * The first can only is shewn in the engraving, but the relative situs- tions of the other cans with respect to the pipes P and S, may be easily understood. * - S M F. S N A. 947 DICTIONARY OF MECHANICAL SCIENCE. reservoir is also saved, nor is any by-wash necessary, as the main sluice on the reservoir that regulates the height of the water in the basin A, acts also as a water-sluice when necessary. When it is necessary to supply any fixed quantity of water from the reservoir, we have only to make an aperture in the basin of the proper size, and, as the water there stands always at the same height, the supply will always be the same. The single weather sluice, fig. 11. One of the applications of this apparatus is, to give, at all times, an equal supply of water to any work, situated like Z, in the last case, where the reservoir is at a great distance from the work, and where it might be inconvenient or expensive to lay a pipe between them as in fig. 4. The description of the last figure applies also to this, only when the can C is filled with water, it shuts sluice BC, instead of opening it as in that figure. In very dry weather, when all the streams between the reservoir and the work are dried up, then it requires all the sluices at the reser- voir to be open, to give the necessary supply to the works, but when the streams begin to flow a little, one sluice at the reser- voir shuts, by the water flowing through aperture 1 into can C; when they increase still further, the water flows out at aperture 2, and along pipe N O, and shuts a second sluice; should they still increase till the water flow out at aperture 3, the third or last sluice shuts, the streams of themselves being now equal to the supply required. As the streams again fall off, the sluices will open, one after another, so as to keep the supply of water at the work always equal. It is necessary, in this case, to have a small reservoir near the work, to contain the water that flows down at night, or when the work is standing; and then this apparatus will be a complete substitute for the last apparatus, fig. 10. The purpose, however, for which this apparatus was invented was different. Having occasion to cut an aqueduct round the bases of some hills, to collect water, and convey it to a reservoir at a considerable distance, I found that to make the aqueduct so large as to convey all the water during floods would be too expensive ; it therefore occurred to me, that if a part of the water could be detained during floods, and brought away gradually afterwards, a much smaller (and of course much less expensive) aqueduct would answer the purpose; I there- fore made a small reservoir at a convenient place, and contrived this sluice to shut during floods, and to open as they decreased; and this answered the purpose intended completely, and was the origin of all the weather-sluices. SLUSS, SLUDGe, or Slush, a soft miry substance, serviceable in manuring land. . SMACK, a small vessel commonly rigged as a cutter, and used in the coasting and fishing trade, or as a tender in the king's service. SMALL-POX, a highly infectious and formidable eruptive fever, which occurs in general but once to the same person. It is distinguished by the appearance of pustules on the third or fourth day of the fever. The face is sometimes dreadfully dis- figured with the variolous corrosion. It is supposed to have existed in China and Hindostan several centuries before it was introduced into Europe. About the year 572 of the Christian era, it appeared at Mecca. From this place it was conveyed to Alexandria, and in the eighth century it was spread over France, Spain, and Italy, by the Saracens, in their progressive expeditions into the regions of the west. SMALT, the last produce of cobalt, a kind of mineral matter, prepared and purified abroad, and brought hither sometimes in blue powder, and at other times in lumps. It is chiefly used with starch, and is generally known by the name of powder blue. SMARTWEED, a troublesome weed, generally found in arable lands, and more commonly called arsesmart. Its juices have been known to remove warts, by frequently rubbing them with its green leaves a little bruised. SMELL, Sense of. The sense of smell is very nearly allied to that of taste, and indeed many of those pleasurabie sensa- tions which are usually referred to the taste, as being received during the actofeating and swallowing, really belong to the smell. The organ of smell is a membrane or skin overspread with nerves, which line the internal cavity of the nostrils, and the surface and cavities of the bones which join the nostrils. This is affected both by the odorous particles' which proceed from external substances through the nose, and by those that come from trade. sº the substances which are eaten : for there is a communication between the nose and the back part of the mouth. The disa- greeable sensations occasioned by smell assist us in the proper choice of food, and prompt us to avoid such noxious vapours as may render the air injurious to health or life. It appears also, that offensive odours in various circumstances, contribute to gene- rate the sense of shame, decency, &c. The pleasures of smell have a direct connexion with those of taste; and in several instances, such is their mutual union and co-operation, that the association appears almost inseparable. The fragrance which arises from the various productions of nature, adds new charms to her landscapes; and the pleasing sensations which enhance our mental enjoyments when inhaling the grateful incense, live in our recollections, when the representations of them are again brought before us in poetry and painting. SMELTING, in Metallurgy, the fusing or melting of the ores of metals, in order to separate the metalline part from the earthy, Stony, and other parts. SMITHERY, or SMITHING, a manual art by which an irre- gular lump of iron is wrought into any intended shape. SMOCK, LADY’s, or Bitter Cress, Cardamine Amara, in Agriculture, a plant of the weed kind, found in coppices, and on the banks of rivers, which sheep are said sometimes to eat. Some think the common sort is useful in epilepsies. . SMOKE, a humid matter exhaled in form of vapour by the action of heat, either external or internal. It consists of pal- pable particles elevated by means of the rarefying heat, or by the force of the ascending current of air, from bodies exposed to heat. Sir Isaac Newton observes, that smoke ascends in chimneys by the impulse of the air in which it floats; for that air being rarefied by the fire underneath, hath its specific gravity diminished, and being thus determined to ascend, it carries up the smoke along with it. Smoke of fat unctuous wood, such as fir, beech, &c. makes what we call lamp black. Smoke arising from the combustion of vegetables, is a mixture of water, oil, volatile salts, and all the gaseous products which result from the combination of vital air with the several prin- ciples of the vegetable. In the Philosophical ºransactions, we have the description of an engine invented by Mons. Dalesme, which consumes the smoke of all sorts of wood, leaving nothing to affect either the sight or smell. It consists of several iron hoops, four or five inches in diameter, which shut into one another, and is placed on a trivet, but its mode of operation we have not seen. SMokE Sail, a small sail, hoisted against the fore-mast when the ship rides head to wind, to give the smoke of the gal- ley an opportunity of rising, and to prevent its being blown aft on to the quarter deck. - SMUGGLING, in civil economy, the importing contraband goods, or the selling of such as the law has made excisable, without paying the legal impost. Several severe laws have been enacted against this species of traffic, but no measures hitherto adopted have been able wholly to suppress the illicit The preventive service holds it under the most power- ful restraints. SMUT, a disease in corn which destroys entirely the germ and substance of the grain, SNAIL. See HELI &. - SNAKE in Zöology, a genus of serpents, the characters of which arc, that they have abdominal and subcaudal scales. Of the snake tribes the species are vastly numerous, some of which are inoffensive, while others are dangerous in the highest degree. Those that live in warm climates sometimes grow to an enormous size, and many instances of their strength have been recorded, which appear almost incredible. In these sultry regions, their poison is also more acute than in other portions of the globe, but in general the largest have not been found the most venomous. Perhaps, of none is the poison more virulent than that of the rattlesnake. SNAke, Sea, a strange kind of fish, of the eel kind, said to reside in the northern seas, and to have been seen on the coasts of Norway, and on the shores of North America. The size and length of these creatures seem to be almost incredible. Some accounts represent them from fifty to seventy feet long, and others have extended their length to six hundred feet. There can be little doubt that some of these statements have been 948 S. N. O S O A 10 ICTIONARY OF MECHANICAL SCIENCE. exaggerated, the calculations of length having been made in all cases without actual measurement. The evidences, however, in favour of such creatures actually existing, have of late been so numerous and convincing, that the fact seems to be placed beyond the reach of all reasonable suspicion. . . . SNAke Root, Serpentaria, in Medicine, the root of a species of aristolochia. Prior to the discovery of America, only two kinds of serpentaria were known; but since that event, several others have been added, such as the Virginian, the Canadian, and the Brazilian. The snake-root of Virginia was esteemed by the Indians as a sovereign antidote against the bite of the rattlesnake. Some travellers assert, that the smell of this antidote drives the rattlesnake away, on which account the Indians, when travelling in dangerous places, tie a portion of snake-root to the end of their staff, to preveat being bitten. In a dried state it is imported into this country in bales, each con- taining from two to five hundred weight. The smell is aroma- tic, not unlike that of valerian ; and the taste is warm, sharp, and bitter, somewhat resembling that of camphor. It is highly esteemed for various medical purposes. *. SNAke Stone, a species of shell, of a flattened spiral figure, containing many circumvolutions, exhibiting a distant resem- blance to a snake. coiled up, and in that state becoming petri- fied. These snake-stones, generally described as ammonites, are very numerous in various parts of the world, but the race of animals, of which these are the remains, is supposed long since to have become extinct. SNAke Weed, in Agriculture, a common grass, frequently found by the sides of roads, which, if cultivated, would produce seeds answering the same purposes as those of buck-wheat. It is annual, or at most biennial, in its growth. SNAKE Wood, in the Materia Medica, is the wood or root of the tree which affords the mwa, vomica. It is brought from the East Indies under the name of lignum colubrinum, in pieces about the thickness of a man’s arm, covered with a rusty- coloured bark, and is internally of a yellow colour, with whitish streaks. though it is somfewhat faint, and, on being tasted, the flavour is bitter. - SNARING, is the winding small ropes spirally round a large one, the former lying in the intervals between the strands of the latter, and is frequently termed WorMING, which article see. SNAPDRAGON, in Botany, see ANTIRRHINUM. The smaller sort of snapdragon is a troublesome weed in corn fields. SNATCHBLOCK, a block having an opening in one of its sides, wherein to fix the bight of a rope occasionally. by some termed a rouse—about block. SNEEZING, in Medicine, sternutatio, a violent convulsive motion of the muscles of respiration, which is preceded by a deep inspiration that fills the lungs, and then forces the air violently through the nose, while the under jaw is at the same 'moment closed. The effort shakes the head, and the whole body. This convulsive sensation is always excited by some irritation affecting the inner membrane of the nose; the air, therefore, which in coughing is expelled through the mouth, is vehemently driven through the nose, for the purpose of expel- ling that irritation. :- - SNIPE See Scolop Ax. SOAL-FISH. See PLEURONECTEs. SNORING, in Medicine, a sound produced by sleeping per- sons, in particular positions, apparently occasioned by the vibra- tions of the palate, in a state of relaxation, when the respira- tion is performed by breathing through the mouth and nose at the same time. SNOW, a well-known substance, formed by the freezing of the vapours in the atmosphere. It diſſers from hail and hoar- frost, in being as it were crystallized, which they are not. This appears on examining a flake of snow by a magnifying glass; when the whole of it will appear to be composed of fine shining spicnla, diverging like rays from a centre. As the ſlakes fall down through the atmosphere, they are continually joined by more of these radiated spicula, and thus increase in bulk like the drops of rain, or hailstones. . The whiteness of snow is owing to the small particles into which it is divided: for ice when pounded will become equally white. According to Beccaria; clouds of snow differ in nothing | When rasped, this wood yields an agreeable smell, This is from clouds of rain but in the circumstance of cold that freezes 'them. Were we to judge from appearances only, we might ima- gine that so far from being useful to the earth, the cold humility of snow would be detrimental to vegetation. But the experience or all agcs asserts the contrary. Snow, particularly in those northern regions where the ground is covered with it for seve- ral months, is of service to the earth, by guarding the corn or other vegetables from the intenser cold of the air, and especially from the cold piercing winds. It has been a vulgar opinion, very generally received, that snow fertilizes the land on which it falls, more than rain, in consequence of the nitrous salts which it is supposed to acquire by freezing. But it appears from the experiments of Margraaf in the year 1731, that the chemical difference between rain and snow water is exceedingly small. —Different vegetables are able to preserve life under different degrees of cold, but all of them perish when the cold which reaches their roots is extreme. Providence has, therefore, in the coldest climates, provided a covering of snow for the roots of vegetables, by which they are protected from the influence of the atmospherical cold. The snow keeps in the internal heat of the earth which surrounds the roots of vegetables, and de- fends them from the cold of the atmosphere. - - S.Now, a vessel equipped with two masts, resembling the main and fore masts of a ship, and a third small mast just abaft the main-mast, carrying a sail nearly similar to a ship's mizzen; the foot of this mast is fixed in a block of wood, or kind of step, upon the deck, and the head is attached to the after- part of the main-top. The sail is called a try-sail, and hence the mast is termed a try-sail mast. When sloops of war are rigged as snows, they are furnished with a strong rope called a horse, instead of the try-sail mast, the fore part of the sail being attached by rings to it. This is generally the largest of all two-masted vessels employed by Europeans, and is reckoned the most convenient for navigation. - - º: SNOW Bird, in Ornithology, a bird that appears in Scot- land in severe weather, and deep snows. It is sometimes called snow-ſlakes, and occasionally breeds in the Highlands, on the summits of the highest hills, but the greater part emi- grate from the extreme north, and their appearance indicates a rigorous season. - e . . SNow Drop. See GALANTHUs. - S.Now Grotto, an excavation made by the waters on the side of Mount Etna, by making their way under the layers of lava, and by carrying away the bed of puzzolana below them. This place is used for a magazine of snow; for in Sicily at Naples, and particularly at Malta, they are obliged, for want of ice, to make use of snow for cooling their wine, sherbet, and other liquors, and for making sweetmeats. See Red SNow. SNow Plough, a contrivance for the purpose of clearing the roads of snow. It has been long used in Sweden, and has of late years been introduced into this oountry. It consists of boards brought to a point in the front, which enters the snow, and spreads behind to any given width which may be required. In this manner it is driven forward through the snow by horses, and the snow is thrown off on each side somewhat like furrows by the plough used in agriculture. . . S.Now Stone, in Natural History, a beautiful stone found in some parts of America. It is richly variegated, and when | polished exhibits an appearance resembling snow falling in all its whiteness upon a jetty surface. - .. - . SNUFF, a preparation of tobacco, made by reducing it into a powder, fit to be taken in at the nose, to clear the head of pituita. Many other ingredients are mixed with the tobacco, to give the snuff a more agreeable scent. The sorts already in use are too numerous to be named, and every month furnishes new combinations, possessing virtues till then unknown. SOAP, in domestic economy, a composition of caustic alkali, salt, and oil, or other grease. The earths, and the other metallic oxides, also combine with fat and oils, forming neutral com- pounds. The former have been called earthy, and the latter metallic soaps. Soaps in common use are made with the fixed alkalis, combined with different kinds of fat and oil. These are divided into two principal varieties, hard and soft, which, in their being manufactured, undergo distinct processes. There are few compounds in which the chemical art appears to greater advantage in common estimation, than in the formation of soap. S. O. D. S O L. 949 DICTIONARY OF MECHANICAL SCIENCE, Soap refuse, and soap suds, and most kinds of soapy mixture, have been found to be highly valuable as manure, and great promoters of vegetation. SoAP. Stone, a species of steatite. The name is derived from its colour, and from the peculiar unctuous sensation which it imparts to the feeling, which resembles that of white soap. It is sometimes striped and mottled with veins and spots of a dull purple. The only place in England where this stone is found, is at the Lizard, in Cornwall, connected with veins of | serpentine, to which rock it seems nearly allied. It is much used in china manufactures. - Soap Berry Tree. The berries of this tree are about the size of a musket bullet, and are winged with leaves. The skin and pulp are used as soap without any mixture whatever, and, in the cleansing of linen, they are a valuable and cheap substi- tute; but being of an acid nature, the finer articles of dress rot much sooner than under common soap. These berries are much used by the negroes. They are also said to have many medicinal virtues. - SOAPER'S WAste. See SoAP. SOAPY Rock. See So AP Stone. SOCCAGE, an ancient tenure, by which lands were held on condition of ploughing the lord’s lands, and doing the other operations of husbandry, at their own charges. - SOCCUS, in Antiquity, a kind of high shoe reaching above the ankle, worn by comedians, as the cothurnus was by tragedians. SOCIETY, an assemblage or union of several persons in the same place, for their mutual assistance, security, interest, or entertainment. For the origin of civilized society, various causes have been assigned. To investigate the numerous theo- ries that have been presented to the public on this interesting topic, would be an almost endless task. It would be scarcely less difficult to enumerate and characterize the various Societies that have sprung up in civilized states. SOCINIANS, in Church History, a sect of Christians so call- ed from their founder Faustus Socinus, a native of Sienna, in Italy: they ascribe proper divinity to the Father only. SOCK, in Ágriculture, the share of a plough, or that part which opens the land. SOCLE, or Zocle, in Architecture, a flat square member under the bases of pedestals, statues, vases, &c. which it serves as a foot or stand. - SOCO, in Ornithology, a Brazilian bird of the heron kind, remarkable for the length of its neck, and its variegated colours. SOD, in Agriculture, a portion of turf or sward, cut or dug up. It also signifies the soil or earth. The square pieces of surface turf and earth, that are cut up in forming embankments and earth ſences, are likewise termed Sods. SODA. This is found to be compounded of oxygen and a metallic basis called sodium ; but as it is found thus com- bined, and as it is only in this state of combination that it is of the smallest importance, it deserves to be specially no- ticed. It was formerly called mineral alkali, as it is found in mineral seams and crusts; also in very great abundance in certain lakes near Alexandria in Egypt, in the dry sea- son, being brought thither by the water which enters from the neighbouring country during the overflow of the Nile, and precipitated by the evaporation of the sun during the dry season. Barilla is the impure soda obtained by burning the salsola soda and other plants near the sea. Kelp is still more impure, containing only a small portion of pure alkali. It is obtained by burning sea-weed. For the purposes of commerce, soda is obtained from common salt, or muriate of soda. SODALITE, in Mineralogy, is a stone that derives its name from the large portion of mineral alkali that enters into its composition. Its colour is a bluish green. SODE-SHOOTS, in Botany, is a name given by some to the tree whose inspissated juice is the gum tacamahacca of the shops. - - §§oruM, in Chemistry, is a simple body, and a metal. This was discovered by Sir Humphrey Davy in the year 1807. A few days prior to this event he had ascertained, that potass was a compound of a peculiar metal combined with oxygen; and he now found, that soda consisted of a metallic substance com- bined with oxygen. He first produced it by exposing soda to the action of the galvanic battery. It is now produced by 101-2. fusing soda or muriate of soda with potassium. The potassium combines with the oxygen in the soda, and with the chlorine in the salt, leaving pure sodium. The metal is white, resembling silver, and having the same metallic Justre. . SOFA, in the East, is a kind of alcove raised about six inches above the floor of the apartment in which it appears. With princes it is a place of state, where visitors of distinction are received. When this ceremony is omitted, 1t is considered as a mark of disrespect. Sofa, with us, is a piece of furniture that may be ranked among the refinements and luxuries of civilized life. It serves either as a seat or couch, on which the occupier may sit or stretch himself at ease. The frame is of timber, and extends about six feet in length, and is sufficiently wide to render the seat comfortable. Sofas are covered with cotton, hair cloth, damask, or more costly articles, and generally stuffed with horse hair, and furnished with moveable cushions; and sometimes with mattrasses formed of the same materials. The sopha has been immortalized by the poet Cowper in his “Task.” * SOFFITA, in Architecture, any timber ceiling, formed of cross beams, or flying corniches, the square compartments or pannels of which are enriched with sculpture, painting, or gilding. SOFT CHAik, a sort of fossil marl, which readily becomes blended with common vegetable mould, and therefore forms an excellent manure. It is chiefly valuable in lands that are stiff and unyielding. SOIL, in Agriculture, is a general name applied to the sur- face of all sorts of land which will support vegetation. It is also more particularly applied to the fine powdery materials which have been gradually formed by time, from the various earthy and other bodies in nature, being ground down and in- corporated with each other in divers states and proportions. It is therefore obvious that there must be great diversities of soil in different districts. The stratum which lies next below, is generally denominated the subsoil. Professor Davy, in an excellent paper on the analysis of soils, observes, that the sub- stances which are found in soils are certain mixtures or combi- nations of some of the primitive earths, animal and vegetable matter in a decomposing state, certain saline compounds, and the oxide of iron. - SOILING, in Agriculture, the practice of supporting animals of various kinds, in the summer season, with green food of different sorts cut daily, and given to thern in racks, in the houses, stalls, or yards, instead of sending them to the fields. SOLANUM, in Botany, an ample genus, comprising various kinds of nightshade and other deadly plants. SOLDER, Sodder, or Soder, a metallic or mineral compo- sition used in soldering or joining other metals. , Solders are made of gold, silver, copper, tin, bismuth, and lead, usually ob- serving, that in the composition there shall be some of the metal that is to be soldered mixed with some higher and finer metals. SOLDERING, the joining and fastening together of two pieces of the same metal, or two different metals, by the fusion and application of some metallic composition, on the extremi- ties of metals to be joined. - SOLDIER, a military man, who voluntarily enlists to serve a prince or state for pay. The term includes officers of all ranks, as well as privates. The volunteer serves of his own accord without pay ; the vassal is compelled to serve at his own expense ; while the soldier, though a volunteer when he enters, is remunerated for his services, but is no longer free. SOLE of A GUN Port, is the lower part of it, and is more properly called the port sill. Sole of the Rudder, a piece of timber attached to the lower part of it, to render it nearly level with the false keel. SOLECISM, in Grammar, a false manner of speaking, con-, . trary the use of language and the use of grammar, either in re- spect of declension, conjugation, or syntax. SOLEN, RAzor SHEATH, or knife-handle shell, a genus be- longing to the class of vermes, and order of testacea. The ani- mal is an asceidia. The shell is a bivalve, oblong, and opening at both sides; the hinge has a tooth shaped like an awl, bent back, often double, not inserted into the opposite shell; the rim at the sides somewhat worn away, and has a horny cartila- ginous hinge. 1 I 950 S O' N S O U DICTIONARY OF MECHANICAL SCIENCE. - SOLICITOR, a person employed to take care of and manage suits depending in the courts of equity. - - SOLID. Geometricians define a solid to be the third spe- oies of magnitude, or that which has three dimensions, viz. length, breadth, and thickness or depth. Geometric solids are the regular figures cut in wood or crystal. - - SOLIDITY, is that property of matter by which it excludes all other bodies from the place which itself possesses. SOLO, in Music, a term used in pieces consisting of several parts, to mark those that are to perform alone. SOLSTICE, in Astronomy, is the time when the sun is at the greatest distance from the equator, and is thus called, because he then appears to be stationary in the zodiac ; which arises from the obliquity of our sphere. There are two solstices in the year, generally denominated the summer and the winter sol- stice. The former is on the 21st of June, when the sum is in the tropic of Cancer, and all the inhabitants of the northern hemai- sphere have their longest day: the latter is on the 21st of Decem- ber, when the sun enters the first degree of Capricorn, and makes the shortest day to the above inhabitants. To all those who live on opposite sides of the equator, the longest and short- est days, and the summer and winter seasons, stand reversed. SOLUTION, in Chemistry, denotes an intimate mixture or perfect union of solid bodies with fluids, so as seemingly to form one homogeneous liquor. - SOMATOLOGY, comprehends our knowledge of bodies, or external substances. The properties of bodies, says Leslie, are detected by the senses, either from immediate observation, or through the application of experiment, and the aid of instru- ments. The more obvious properties are revealed to us merely by touch or sight; but the penetration of the telescope has enabled us to survey vast systems of worlds, dispersed through the remotest heavens; while the opposite power of the micro- scope has brought within our view, from the very verge of existence, a miniature creation of organized beings. Again, the most careless observer can hardly have omitted to perceive that the air is a compressible fluid, while it requires a very delicate experiment to discover the same property in water. The properties of body are either essential and permanent, or they are contingent, and susceptible of change or variation. Body is essentially, 1. extended; 2. figured;. 3. impenetrable; 4, divisible ; 5. porous; 6. contractile, or distensible. SOMMITE, a mineral which is found in small crystals in the dava on the sides of mount Somma, which is a part of Vesuvius. SOMNAMBULISM, sometimes called Noctambulism, or Sleepwalking. In this singular condition of the body, a person performs many voluntary actions, implying a certain degree of perception of the presence of external objects, but without any consciousness while the actions are performed, and without any recollection of them when consciousness returns. Of this very remarkable phenomenon many very singular accounts have been recorded, but the physical causes of sleepwalking remain yet in a great measure to be explored. Dugald Stewart, in his Elements of the Philosophy of the Human Mind, has the follow- ing observations in reference to Somnambulism: “There are many cases in which sleep seems to be partial ; that is, when the mind loses its influence over some powers, and retains it over others. In the case of Somnambulism, it retains its power over the limbs, but it possesses no influence over its own thoughts, and scarcely any over the body, excepting those par- ticular members of it which are employed in walking.” Some, indeed, have doubted whether the state in which these persons are, who thus walk and act, can justly be denominated sleep. Pr. Cheghorn has pointed out several particulars in which this condition differs from sleep; and Dr. Darwin, in his Zoonomia, considers it as belonging to reverie, or as approximating to epilepsy, or catalepsy, rather than to real sleep. It must, however, be acknowledged, that these are but mere opinions and theories, totally unsupported by any thing conclusive, and nearly all we know with certainty is, that the facts connected ith Somtarnbulism are too obvious to be denied, while their causes have hitherto in a great degree eluded all research. SONATA, in Music, a piece or composition intended to be performed by instruments only. --. ... SONCHUS, in Botany, the Sow Thistle, so called because it is a plant of which swine are remarkably fond. ; SONG, in Poetry, a little composition, consisting of easy and natural verses set to a tune in order to be sung. SoNG of Birds, has been defined to be a succession of three . or more different notes, which are continued without interrup- tion, during the same interval, with a musical bar of four crotchets in an adagio movement, or whilst a pendulum swings four seconds. . - SONNA, a book containing Mahometan traditions, which all true Mussulmen are required to believe, though they be not included in the Koran, to which the Sonna is considered as a supplement. - SOOT, a substance deposited from the flame of burning vegetables. . - SOPHI, or Sofi, a title of quality given to the emperor of Persia, which signifies wise, or sage, or philosopher. - SOPHISM, in Logic, &c. an argument which carries much of the appearance of truth, and yet leads to an error. SORCERY, the crime of witchcraft, or divination, by the assistance of evil spirits. - - SOREX, S.H.Rew, a genus of quadrupeds of the order ferae. The generic character is, front teeth in the upper jaw two, long, bifid; in the lower, two or four, the intermediate ones shorter; canine teeth, several on each side; grinders cuspidated. SORTES, in Antiquity, a method of deciding difficult cases by lots, dice, or the drawing of tickets. . | SOUL, the spirit of man, which, in his present state, is adapted to the organization of his body, but which is capable of subsisting when it becomes disembodied. The word soul is understood in several other senses. SOUND, on the coast of Norway in particular, is used for any opening of a river, or any gulf, or deep inlet of the sea, in the same sense as “deep” on the coast of Germany. In other parts it is more usually understood of a passage between the main land to which it is contiguous, and some island, which together form a strait or passage within such lands. SOUND, or Hearing, sense of. The external air collects and modifies sounds; and by a long channel communicates them to the internal ear; this consists, in the first place, of what is called the drum of the ear, which is a small cavity, closed to- wards the opening of the ear by a delicate membrane. In the drum are three or four very small bones, furnished with mus- cles and joints. From the drum are several openings, one of which is to the mouth ; the others communicate into the differ- ent recesses of the ear, One of these leads into the labyriath, which consists first of a small irregular cavity, next of three semicircular canals, and lastly of a winding spiral canal, not unlike some sea shells. All these parts of the cavity are lined with a very delicate membrane, and filled with a watery fluid, which conveys to the portions of the nerve in contact with it, the vibrations received from the membrane which separates the labyrinth from the drum of the ear. The vibrations of the air act upon the drum, and thus set in motion the series of small bones in the cavity of the drum; these communicate the vibra- tions to the membrane which separates the drum from the labyrinth, and this (as before mentioned) produces vibrations in the watery fluid in the several parts of the labyrinth, and conveys to the nervous branches, which line the labyrinth, the vibrations originally produced on the drum. The mechanism is . complicated, but what we understand must increase our reve- rential admiration of the skill which produced it. To illus- trate the cause of sound, it is to be observed, 1st. That a mo- tion is necessary in the sonorous body, for the production of sound. 2dly. That this motion first exists in the small and insensible parts of the sonorous bodies, and is excited in them by their mutual collision against each other, which produces the tremulous motion so observable in bodies that have a clear sound, as bells, musical chords, &c. 3dly. That this motion is communicated to, or produces a like motion in, the air, or such parts of it as are fit to produce and propagate it. Lastly, that this motion must be communicated to those parts that are the proper and immediate instruments of hearing. The sonorºus body having made its impressien on the contiguous air, that impression is propagated from one particle to another, accord- ing to the laws of pneumatics. Sound is conveyed through air with great rapidity. The motion of sound through the air is at the rate of about 13 miles in an hour. S O U S O U 951 DICTIONARY OF MECHANICAL SCIENCE. - SOUND, Velocity of. By Dr. Olinthus Gregory. (Ab- stracted from a paper by Dr. G. in the Transactions of the Cambridge Philosophical Society for 1824.) The results of the experiments hitherto made to determine the velocity of sound present an extraordinary discrepancy; thus, Feet per second. Feet per second. Mr. Roberts assigns a | Cassini de Thiery.... 1107 velocity of . . . . . . . . 1300 || Meger . . . . . . . . . . . . . . 1105 Mr. Boyle . . . . . . . . . . . . 1200 | Derham . . . . . . . . . . . . 1142 Mr. Walker and Du- Muller . . . . . . . . . . . . 1109 hamel . . . . . . . . . . . . . . 1338 Picket . . . . . . . . . . . . 1130 Mersenne . . . . . . . . . . . . 1474 Arrago . . . . . . . . . . . . 1106-32 The Florence Academy. 1148 A series of experiments undertaken by Dr. Gregory pro- duced the following results: Velocity of sound. Feet. Velocity of sound.' Feet. Fahr. therm. 279 . . 1094'2 || Fahr. therm. 609 . . l l 12 Ditto . 33 . . 1099] we § 1114; Ditto . 35 . . 1102 Ditto. 64 . . iii. Ditto . 45 . . 11073 & § 1116 Ditto . 59 . . 1109% Ditto. 66 . . iii.; Of these results, some have been obtained in the day-time, others in the night; some when the sound has been transmitted over the surface of the earth, others when it has been trans- mitted over the surface of water; some are the result of direct sound, others of both direct and reflected sound; some from the report of cannons, others of muskets, others from the sound of bells. Were these the only experiments (says Dr. G.) on the subject that had ever been made, I should not regard them sufficiently extensive to justify me in deducing from them even an approximative rule. But as they have been made with great care, I may at least venture to present a rule, which, while it includes, with only slight discrepancies, all the preced- ing results, is simple enough to be easily recollected by prac- tical men; and may, perhaps, be employed in our own climate. It is this : At the temperature of freezing, 33°, the velocity of sound is 1100 feet per second. d - - For lower temperatures deduct For higher temperatures add $ half a foot. - Fº §: H. : for every degree of difference from 330 on Fahr, therm, the result will shew the velocity of sound, very nearly, at all such temperatures. Thus, at the temperature of 50°, the velocity of sound is 1100 × 4 (50–33) – 1108}, feet. - At temperature 60°, it is 1100 + 3 (60–33) = 11134 feet; agreeing with the experimental result quite within the limits of a practical rule. The above practical rule, so far as it may be entitled to con- fidence, may be useful, 1st, to the military man, in determining the distance of an enemy’s camp, of a fortress, a battery, &c.; 2nd, to the sailor, in determining the distance of another ship, &c.; 3rd, to the landsurveyor, in ascertaining the length of base lines, &c. in conducting the survey of a lordship or county; 4th, to the philosophic observer, in appreciating the distances of thunder clouds during a storm. Yet in either of these appli- cations, the rule must be regarded as approximative only; be- cause few practical men can be expected to possess a time- measurer for less intervals than tenths of seconds, if, indeed, so small : and an error of a tenth of a second will occasion a mistake of from 37 to 40 yards in the estimate of the distance. Beyond this, however, the error need scarcely ever extend ; because a mean of five or six careful experiments will usually give the interval to a degree of correctness far within the limits just specified. Indeed, an error of from 30 to 40 yards in a distance of three or four miles, will, on most occasions, where such approximative estimates are required, be of but small con- sequence. When the distance exceeds four miles, this method of approximating to it can only be employed under favourable circumstances of a very quiescent atmosphere, &c. Combining the results of experiments here recorded with those which have been formerly deduced by Derham and others, we may, I think, conclude unhesitatingly, 1st, That sound moves uniformly, at least, in a horizontal direction, or one that does not deviate greatly from horizontality. 2nd, That the difference in intensity of a sound makes no appreciable difference in its velocity.* 3rd, Nor, consequently, does a difference in the instrument from which the sound is emitted. 4th, That wind greatly affects sound in point of intensity; and that it affects it also in poinf of velocity. , 5th, That when the direction of the wind concurs with that of the sound, the sum of their separate velocities gives the apparent velocity of sound; when the direction of the wind opposes that of the sound, the difference of the separate velocities must be taken. 6th, That in the case of echoes, the velocity of the reflected sound is the same as that of the direct sound. , 7th, That, therefore, distances may frequently be measured by means of echoes. 8th, That an augmentation of temperature occasions an augmentation of the velocity of sound, and vice versä. Sou ND, the French academicians made, in 1738, some expe- riments for measuring the velocity of sound: the Board of Longitude renewed these investigations in modern times, with all possible precision, when they found that the velocity of sound in the air, at the temperature of 55 degrees Fahrenheit, differs very little from 1044 feet per second. . Sound BoARD, in on Organ, is a reservoir irto which the wind, drawn by the bellows, is conducted by a port vent, and hence distributed into the pipes placed over holes in its upper parts. Sound, in Geography, denotes in general any strait, or inlet, of the sea, between the two headlands. - SOUNDING, the operation of trying the depth of the water, and the quality of the ground, by means of a plummet sunk from a ship to the bottom. For sounding there are two plum- mets used, one of which is called the hand-lead, weighing about eight or nine pounds; and the other, the deep sea-lead, weigh- ing from twenty-five to thirty pounds, and both are shaped like the frustum of a cone or pyramid. The former is used in shallow waters, and the latter at a great distance from the shore, particularly on approaching the land after a sea voyage. Accordingly the lines employed for this purpose are called the deep sea-lead, and the hand lead-line. The hand lead-line, which is generally twenty fathoms in length, is marked at every two or three fathoms, so that the depth of water may be ascertained either in the day or night. At the depth of two or three fathoms there are marks of black leather; at five fathoms there is a white rag ; at seven a red rag; at ten black leather; at thirteen black leather; at fifteen a white rag ; and at seventeen a red rag. Sounding with the hand lead, which is called heaving the lead by seamen, is generally performed by a man who stands in the main-chains to windward. Having the line all ready to run out without interruption, he holds it nearly at the distance of a fathom from the plummet, and having swung the latter back- wards and forwards three or four times, in order to acquire the greater velocity, he swings it round his head, and thence as far forward as is necessary; so that by the lead's sinking while the ship advances, the line may be almost perpendicular when it reaches the bottom. The person sounding then proclaims the depth' of the water, in a kind of song, resembling the cries of London hawkers. Thus if the mark of five fathoms is close to the surface of the water, he calls, “By the mark five,” and as there is no mark at four, six, eight, &c. he estimates those num- bers, and calls “By the dip four.” If he judges it to be a quar- ter or a half more than any particular number, he calls, “And a quarter five,” “And a half four,” &c. If he perceives the depth to be three quarters more than a particular number, he calls it a quarter less than the next; then at four fathoms and three quarters, he calls “A quarter less five,” &c. The deep-sea lead is marked with two knots at twenty fathoms, three at forty, four at fifty, and so on to the end. It is also marked with a single knot in the middle of each interval, as at twenty-five, thirty-five, forty-five fathoms, &c. To use this lead more effec- tnally at sea, or in deep-water on the sea-coast, it is usual pre- viously to bring-to the ship in order to retard her course ; the lead is then thrown as far as possible from the ship on the line- of her drift, so that as it sinks the ship drives more perpen- * The consecution of the notes in a tune, notwithstanding the difference in their intensity, being uninterrupted when heard at a distance, furnishes an elegant and decisive confirmation of this proposition. 952 S P A S P E DICTIONARY OF MECHANICAL | SCIENCE. dicularly over it. The pilot feeling the lead strike the bottom, readily discovers the depth of the water by the mark on the line nearest its surface. - - - º In Soundings, implies the being so near the land, as that a deep sea lead will attain the bottom, which is seldom practi- cable in the ocean. º . . Soundings, is also a name given to the specimen of the ground; a piece of tallow being stuck upon the base of the deep-sea lead, brings up distinguishing marks of the bottom, as sand, shells, ooze, &c. which adhere to it. . The soundings, i. e. the depth of the water and the nature of the ground, are carefully marked in the log-book, as well to determine the dis- tance of the place from the shore, as to correct the observations of former pilots. e Sound iNG Rod, a long piece of iron, marked with feet and inches, which being let down by a line in a groove by one of the pumps, indicates what water, there is in the well, and conse- quently whether or not the ship leaks. • - SOUP, a kind of pottage made of bread, broth, or the juice of flesh, with various other ingredients, usually served up at the beginning of a meal. Portable Soup, is a kind of cake, formed of concentrated broth, which being freed from all fat, and by long boiling having the most putrescent parts of the meat evaporated, is reduced to the consistence of glue, and will keep sound for many years. In long voyages this has been found to be a most valuable article of food. - SOUTH, one of the four cardinal points of the compass. SOUTHING of the Moon, the time at whigh the moon passes the meridian of any particular place. - SOWING, in Agriculture, the act of scattering, or putting the seeds of grain, plants, &c. on or into the ground, in order to their producing crops. SPACE, in Geometry, denotes the area of any figure, or that which fills the interval or distance between the lines that ter- minate it. - O SPAce, in Mechanics, the line a moveable body, considered as a point, is conceived to describe by its motion. . . . ſº SPADE, a well-known tool used in digging the soil; but its form is varied, according to the purposes to which it is applied. SPADING, in Agriculture, is the taking off the sward or surface of grass land by means of the paring spade, with an intent to burn it. ºr SPAN, among Sailors, a small line or cord, the middle of which is usually attached to a stay, whence the two ends branch outwards to the right and left, having either a block or thimble attached to their extremities. It is used to confine some ropes which pass through the corresponding blocks or thimbles. To span in the rigging, is to draw the upper parts of the shrouds together by tackles, in order to seize on the catharping legs. SPAN, a measure taken from the space between the thumb's end and the tip of the little finger, when both are stretched out. The span is estimated at three handbreadths, or nine inches. - SPANDRIL, in Architecture, the open space between the outward moulding of an arch, from its impost to the horizontal member or line which surrounds it. - SPANKER, another name for a ship’s Driver, which see. . SPAR, in Mineralogy, a name given to those earths which break easily into rhomboidal, cubical, or laminated fragments with polished surfaces. SPARE, an epithet applied to any part of a ship's equipage that lies in reserve, to supply the place of such as may be lost or rendered incapable of service; hence we say, spare tiller, spare top-masts, spare sails, &c. - SPARROW: See FRING ILLA. SPARROW-PHAWK. See FALCo. - - SPARS, large round pieces of timber, fit for making top- masts, &c. - - SPASM, in Medicine, a cramp : in its modern sense it signi- fies a continued and painful contraction of a muscle, or any portion of muscular fibres, and in this signification it stands opposed to convulsion. - SPATULA, an instrument used by surgeons and apotheca- ries for spreading plasters, &c. SPAVIN, a disease in horses, which being a swelling or stiffness usually in the ham, causes-them to halt, ... * SPAWN, in Gardening, the progeny of plants, or other vege- tables, which consists of such small offsets, suckers, and sprouts, as rise numerously from the root of the parent stock. These being taken off and planted, will readily take root, and become proper plants. - - SPAWN, Mushroom, generated in old hot-beds, stable dung moderately dry, and the yards of livery stables, is the seed whence new crops of mushrooms spring. SPAWN of Fish, the glutinous deposites, whence new genera- tions, that continue the species, arise. Each kind has its own peculiar instinct, in reference to the manner, time, and place, of providing for its young; but the variations and singularities of the tribes belong to the natural history of the species. SPAYING, an operation performed on the females of seve- ral kinds of animals, to prevent any further conception, and promote their fattening. - SPEAKER, of the House of Commons, a member of the house elected by a majority of the votes thereof, to act as chairman or president in putting questions, reading briefs or bills, keeping order, reprimanding the refractory, adjourning the house, &c. The first thing done by the commons, upon the first meeting of a parliament, is to choose a speaker, who is to be approved of by the king, and who, upon his admission, begs his majesty that the commons during their sitting may have free access to his majesty, freedom of speech in their own house, and security. from arrests. . The speaker is not allowed to persuade or dis- suade in passing a bill, but only to make a short and plain nar- rative ; nor to vote, unless the house be equally divided. SPEAKING TRUMPET, a tube formed to collect the im- pulses of sound in speaking, and convey them forward to a dis- tance. See Acoustics. SPEAR. See LAN ce. SPEARWORT, in Botany, the Ranunculus Flamineus, gene- rally deemed poisonous, but frequently used for medical pur- poses. The leaves, bruised to a kind of paste, and applied to thé skin, will soon raise a blister. To sheep it proves very pernicious. SPECIES, a term of relation. It comprises any number of individuals of the same common character, and yet it is less comprehensive than the term genus. That, however, which is a species in one relation, may become a genus in another. Thus, animal is a species as ranged under Body, but it is a genus in reference to Man, who now becomes a species of the more generic term Animal. SPECIES, in Algebra, the characters or symbols made use of to represent quantities. SPECIFIC, in Medicine, a remedy whose virtue and effect is peculiarly adapted to some certain disease, is adequate thereto, and exerts its whole force immediately thereon. SPECIFIC GRAVITY, the relative weight of equal portions of different kinds of matter. For ſluids and solids, the common standard of reference is pure distilled water at 620 Fahrenheit, which a cubic foot will weigh 1000 ounces. The specific gra- vity of water is called 1, or 1000. SPECIFICATION, a statement of particulars given by a builder, an engineer, or artist, describing the dimensions and the peculiarities of the work he is about to undertake. Specifi- cations must always be given when patents are to be obtained. SPECTACLE, some remarkable object which arrests, or is designed to arrest, public attention. It is presumed to be always beheld with some passion or emotion of the mind. SPECTACLES, an optical instrument, consisting of two Jenses set in a frame, and fixed at a convenient distance before the eyes, to assist the sight. Spectacles are said to have been invented about the year 1299; but several individuals claim the honour of this discovery. SPECTRUM, in Optics. When a ray of light is admitted through a small hole, and received on a white surface, it forms a luminous spot. If a dense transparent body be interposed, the light will be refracted in proportion to the density of the medium ; bu if a triangular glass prism be interposed, the light is not merely refracted, but it is divided into seven different rays. The ray of light no longer forms a luminous spot, but has assumed an oblong shape, terminating in semicircular arches, and exhibiting seven different colours. This image is called | the spectrum, and, from being produced by the prism, the pris- S. P. I S P I 953 . DICTIONARY OF MECHANICAL SCIENC E. . matic spectrum. These different coloured rays appearing in different places of the spectrum, shew that their refractive power is different. Those which are nearest the middle are the Jeast refracted, and those which are the most distant, the great- est. The order of the seven rays of the spectrum is the follow- ing: red, orange, yellow, green, blue, indigo, violet. The red, which is at one end of the spectrum, is the least, and the vio- let, which is at the other end, is the most refracted. Sir Isaac Newton found, if the whole spectrum was divided into 360 parts, the number of the parts occupied by each of the colours to be the following:—red, 45 parts; orange, 27; yellow, 48; green, 60; blue, 60; indigo, 40; and violet, 80. These different co- loured rays are not subject to further division. No change is effected upon any of them by being further refracted or reflected; and as they differ in refrangibility, so also do they differ in the power of inflection and reflection. The violet rays are found to be the most reflexible and inflexible, and the red the least. SPECULARES, the name of a genus of fossils of the talc class. SPECULUM, in Catoptrics, is a metallic reflector made use of in catadioptric telescopes, instead of the object-glass used in dioptric telescopes. SPEECH, the act or art of expressing thought by articulate sounds, or signs invented for that purpose. SPEEDWELL. See VERONICA. -- SPELL, a kind of charm to drive away disease by hanging a piece of paper round the neck. It also signifies the extend- ing an indefinite but strange influence over a person, which prevents the regular use of his natural powers. Spell is like- wise used for a given period, during which one man or party relieves another in doing something that is laborious. In this sense it is common among sailors and miners. SPERMACETI. This peculiar oily substance is found in the cranium of the physeter monocephalus, or spermaceti whale. It is obtained also from some other species. SPHERE, in Mineralogy, a mineral composed of nearly equal parts of oxide of titanium, silex, and lime. gº SPH ere, is a solid contained under one uniform 'round sur- face, such as would be formed by the revolution of a circle about a diameter thereof as an axis. SPHERe, in Astronomy, that concave orb, or expanse, which invests our globe, and in which the heavenly bodies appear to be fixed and at equal distance from the eye. SPHERICS, the doctrine of the sphere, particularly of the several circles described on its surface, with the method of pro- jecting the same on a plane. - SPHEROID, a solid body approaching to the figure of a sphere, though not exactly round, but having one of its diame- ters longer than the other. - SPHINX, the Hawk moth, a genus of insects of the order lepidoptera, The generic character is, antennae thickest in the middle, subprismatic, and attenuated at each extremity; wings deflected; flight strong, and commonly in the morning or even- Ing. - SPHINX, in Sculpture, a figure representing a fabulous monster of that name. breasts of a woman, the wings of a bird, the claws of a lion, and the other parts of the body like those of a dog or lion. SPHRAGIDE, or Lemnian Earth, in Mineralogy, a sub- stance resembling fuller's earth, found in the island of Lemnos, in the Mediterranean. It is in high repute in the East as an antidote against poison and the plague, and is dug only once a year, and that with great solemnity. SPICA VIRGINIS, a star of the first magnitude in the con- stellation Virgo. SPICE, any kind of aromatic drug that has hot and pungent qualities; such as pepper, nutmeg, ginger, cinnamon, and cloves. Some include under this term senna, cassia, frankin- cense, &c. - - SPIDER, a creature too well known to require any particu- lar description. Of this genus one hundred and twenty species have been enumerated; and of some, the natural history is exceedingly curious. e SPIELMANNIA, a genus of the didynamia angiospermia class and order. - - sºnia, WoRMGRAss, a genus of plants belonging to the It is portrayed with the head and class of pentandria, and order of monogynia; and in the natu ral system arranged under the 47th order, stellatae. - SPIKE, in Gunnery, to choke up the touch-hole with a nail, or something made on purpose, so as to render that piece of ordnance useless. Spike is also the nail or instrument with which the act is effected. º SPIKING up the Ordinance, a sea phrase used for fastening - a quoin with spikes to the deck close to the breech of the car- riage of great guns, that they may keep close and firm to the ship's sides, and not get loose when the ship rolls, and by that means endanger the breaking out of a butt-head of a plank. SPINACIA, SPINACH, a genus of plants belonging to the class of dioecia, and to the order of pentandria; and in the natural system arranged under the 12th order, holoraceae. SPINDLE, on Ship Board, a sort of iron pin tapering at the upper end to a point. It is fixed into the upper end of the top- gallant mast, so as to carry a vane, which turning thereon hori- zontally, shews the direction of the wind. - * - SPINDLE, is also the name of the lower end or foot of a cap- stan, which is shod with iron, and becomes the pivot or axis on which it turns in the saucer. - SPINE, the backbone in any animal, but, in reference to man, it is the articulated bony pillar at the back of the trunk, forming the foundation or basis of support and connexion to all the other parts of the frame. SPINELL. See RUBY. r SPINET, or SPINNet, a musical instrument ranked in the second or third place among harmonious instruments. SPINNING, the art of combining animal or vegetable fibres into threads or cords, by twisting them together. Wool, silk, cotton, flax, and hemp, are the matters most commonly employ- ed for spinning into threads; and of these most of the vegetable fibres, except cotton, require to be wetted during the operation of spinning, to render them more supple; but cotton, wool, and silk, are spun in a dry state. The machines employed for spin- ning are of very different kinds, and adapted to the materials to be operated upon ; but they have all a spindle, revolving with a rapid motion to twist the fibres which are attached to the end of it, and are supplied in a regular quantity, as fast as the twisting motion of the spindle will form them into a thread; and there is also some provision of a bobbin upon the spindle, to take up and retain the thread when made. The most ancient mode of spinning is by the spindle and distaff, which, though exceedingly simple, was attended with much labour, and as the produce was small, the original method was laid aside. This simple but inconvenient method of spin- ning, however, becomes very efficient, when the spindle, instead of being spun upon the ground, is mounted in a proper frame and turned by a wheel and band: this forms a machine which is called the one-thread wheel, and is still used in the country for spinning wool; the spindle is made of iron, and placed hori- zontally, so that it can revolve freely; and the extremity of the spindle, to which the thread is applied, projects beyond the support. The wheel which turns it is placed at one side, the pivots of both being supported in upright pieces, rising up from a sort of stool. The spinner puts the wheel in rapid motion by its handle, and its weight is sufficient to continue the motion for some seconds; then walking backwards from the spindle, it). the direction of its length, she supplies the fibres regularly, and the motion twists them into a thread; but when a convenient length is spun, the spinner steps on one side, and reaches out that arm which holds the end of the thread, so as to alter the direction of the thread, and bring it nearly perpendicular to the length of the spindle, which motion gathers or winds up the thread upon the middle of the projecting part of the spindle. This being done, she holds the thread in the direction of the spindle, so that it will receive twist, and retreats again to spin a fresh length of thread. For spinning wool, it is not wound round the distaff the same as flax, but the spinner holds a lock of it doubled over the fore-fuger, and draws away the fibres from the middle part of a lock, to do which with regularity is the great art of spinning by hand. A spinning machine more perfect than this is the one-thread flax-wheel, with spindle and flyer; it has the property of con- stantly drawing up the thread as fast as it is spun, instead of spinning a length and then winding it upon the spindle, Ił K 954 S P L S P I DICTIONARY OF MECHANICAL SCIENCE, An improvement was made in the spinning wheel by Mr. An- tis some years ago, which was an application of what Sir Richard Arkwright had before invented. The object is to obviate the necessity of stopping the wheel to remove the thread from one hook to another, in the manner just described. For this purpose the bobbin is made to move regularly backwards and forwards upon the spindle, a space equal to its length, so that every part will in succession be presented opposite the hook over which the thread passes, and thus receive the thread regularly upon the whole length of the bobbin. The in- vention has also another advantage over the old method, which always winds the thread in ridges upon the bobbin, and if the thread breaks in reeling the yarn, the whole bobbin may as well be thrown away, because the thread cannot easily be found again but this improved wheel always winds the threads across upon one another, by which means the end can never be lost. It was not until the latter end of the last century, that spin- ning machines of greater powers were constructed ; but all threads were spun by one of the machines which we have de- scribed; the first being used for cotton and wool, and the other with the bobbiu and flyer, for flax ; but for the very coarse threads, two spindles were applied to the latter machine, and the spinner having the wool wound round a band, tied it round her waist instead of winding it upon a distaff, and was thus able to draw out fibres with each hand, and supply two spindles. The first improvement of any importance in spinning, was that of the spinning jenny invented by Mr. Hargraves, as related in our article Weavi NG. This was followed by the slubbing machine or billy, which by preparing the rovings for the jenny, a work which was previously performed by the hand, was deemed a considerable acquisition. - The inventions of Sir Richard Arkwright soon superseded these machines. His principal invention in the spinning was the introduction of the rollers to draw out or extend the fibres to their full length, which is by this means much more perfectly performed than by the fingers of the spinner. For the imme- diate twisting of the thread, he adopted the spindle, bobbin, and flyer of the old flax-wheel, placed in a vertical position, but added to it the important improvement of raising and lowering the bobbin, to distribute the thread regularly and equally upon all the length of it, the same which we have before described as being applied by Mr. Antis to the common spinning-wheel. The spinning jenny was again introduced, and rendered equal, and for some purposes superior, to the water frame, by Mr. Crumpton, who combined with it the system of rollers, of Sir Richard Arkwright, and called the mule. The great success attending the spinning of cotton by these machines, induced many persons to attempt the spinning of flax and wool by similar means. Short wool, for the manufacture of cloth, is spun by the billy and jenny; but flax and long wool for worsted require very different treatment from cotton and short wool, particularly the flax, owing to the great length of the fibres, and to their being of such irregular lengths; in consequence, when they are extended by the rollers on Arkwright's principle, some fibres will be broken, if the distances between the rollers is too small : and on the other hand, if the distance is too great, the fibres will not be properly extended. The latter, however, is the least evil of the two ; and in consequence, the spinning frames for flax have the rollers, between which the extension or drawing out is effected, placed at a distance of from 14 to 18 inches between the first two pair of rollers, through which the flax passes; the next two pair, six or eight inches; after which it is passed between the third pair of rollers at a distance of five or six inches, and then delivered to the spindles, which are simi- lar to those of the water-frame, but placed in an inclined posi- tion. The rollers are made in a very different way from those for cotton, being only narrow wheels just wide enough to receive the fibres of flax between them ; and the fibres are prevented from getting out sideways by small tin spouts, through which the flax passes, as the rollers draw it forwards. The reason of this is, that the flinty surface of the flax would soon wear a hollow part round a plain roller, which would then let the flax slip through; but the narrow wheel wears down equally over the whole breadth of its edge. The lower pair of these rollers, or wheels, revolves in a small trough of water, in the same planner as a grindstone, and thus keeps the flax constantly and in the interval wet, which is necessary, in order to soften the fibres, and make them spin into a firm and smooth thread. Worsted is also spun in a frame resembling the water-frame of Arkwright, from which it only differs in the relative distances of the rollers, by which the drawing out or extending of the fibres is effected. - Messrs. Clarke and Bugby obtained a patent in 1806, for improvements in a machine for spinning hemp and flax, which is intended to be worked by hand labour, and to be at such a small expense, as to bring it within the reach of small manu- facturers. The inventors state it to be constructed upon such safe and easy principles, that no length of experience is neces- sary to enable children to work it; and that it occupies so lit- tle space, that the machines may be placed in small rooms, out- buildings, and other cheap places. To effect the above purpo- ses, it was necessary to get rid of the flyer fixed upon the spin- dle used in the old machinery for spinning hemp or ſlax, which additions require a power in proportion of five to one ; and also to surmount the difficulty which arises from the want of elasti- city in these substances, and which prevents them from being spun by stretching out, at the same time that the thread is twisted in the manner of the mule or jenny. For further parti- culars see Cotto N. - SPINNING Wheel, in Rope-making, for twelve spinners to spin yarn at the same time is about five feet in diameter, and is hung between two posts fixed in the ground : on its top is fixed a se- micircular frame, called the head, which contains 12 whirls, that turn on iron spindles, with hooks to their front ends to hang the hemp on, and are worked by means of a leather band encircling the wheel and whirls. The whirls are made to run with a truer motion when the head on the rising side of the band has a lar- ger segment of a circle than the falling side; or, in other words, let the base part of the head be longer from the middle than the opposite or failing side, by which means the band will be kept equally tight over the whirls, and consequently the motion will be alike to all. Heads made in this manner have the wheels turned always the same way. SPINSTER, in Law, an addition usually given to all un- married women, from a viscount's daughter downward. SPIRACULA, in Entomology, holes or pores on each side of every segment of the abdomen, through which insects breathe. SPIRAL, in Architecture and Sculpture, implies a curve that ascends winding about a cone or spire, so that all the points thereof continually approach the axis. SPIRAL, in Geometry, a curve line of the circular kind, which in its progress recedes from its centre. SPIRALE, PRoPortionAL, are such spiral lines as the rhumb lines on the terrestrial globe. SPIRIT, in Physiology, the most subtle and volatile part or juice of the body, by means of which its various functions and operations have been supposed to be performed. For Spirits distilled, see ARAc, BRANDY, RUM, &c. Spirit, in Theology, signifies any incorporeal being that possesses intelligence. In the highest sense, God is a spirit; angels, devils, and the souls of men, are spirits. The term is more emphatically applied to the Holy Ghost. On the nature, qualities, and peculiar properties of spirit, the disputations among divines and metaphysicians have been carried to an . almost immeasurable length. SPIRITUALIZATION, in Chemistry, the act of extract. ing spirits from natural bodies. : SPIRRETING, that range of planks which lies between the water-way and the lower edge of the gun-ports withinside of a ship. SPLICING, among Seamen, to join the two ends of a rope together, or to unite the end of a rope to any part thereof, by interweaving the strands in a regular manner. There are Se- veral methods of splicing, according to the services for which it is intended; all of which are distinguished by particular epi- thets. The short splice, is used upon the cables, slings, block-strops and in general all ropes which are not intended to run through blocks, or where the splice is not in danger of being loosened. It is made by untwisting the ends of two ropes, or the ends of one rope, and having placed each of the strands of one opposite, i. two strands of the other, by pene- S P O S P R 955 DICTIONARY OF MECHANICAL SCIENCE. trating the latter with a fid or marline spike, parallel to the axis or length of the rope. The long splice, occupies a greater extent of rope, but by the three joinings being fixed at a distance from each other, the in- crease of bulk is divided ; hence it is much neater and smother than the short splice, and better adapted to run through the channel of a block, &c. for which use it is generally intended. , The eye-splice, forms a sort of eye or circle at the end of a rope, and is used for splicing in thimbles, bulls-eyes, &c. and sometimes on the end of block-strops. The strands are therefore untwisted, and their extremities thrust through the three strands in that part of the rope whereon the splice is to be formed, and thence passing over the surface of the second strand, they are again thrust through the third, which completes the operation. There are other names for splices made in a similar manner to the eye-splice, but for a different purpose, being chiefly used in lead-lines, log-lines, and fishing lines, where the short splice would be liable to separation, as being frequently loosened by the water. It is made by splicing the ends of two lines at a short distance from each other; and the extremities of each being interwoven into the bight of the other lines, becomes dou- ble in the extent of the splice. SPLINTERS, the pieces of a ship's side, masts, decks, &c. which being knocked off by a shot, acquire great velocity, and frequently do more damage among the men than the shot itself. SPLINter-Netting, sinnet made into nets, and nailed upon the inner part of the ship's sides, to lessen the effect of the splinters. SPOILS, whatever is taken from an enemy in war; it is frequently denominated booty. SPONDEE, Spon DEUs, in ancient Poetry, a foot consisting of two long syllables as, om-nes. SPONGIA, Sponge, in Natural History, a genus of animals belonging to the class of vermes and order of zoophyta. It is fixed, flexible, and very torpid, growing in a variety of forms, composed of reticulated fibres, or masses of small spines inter- woven together, and clothed with a living gelatinous flesh, full of small mouths or holes on its surface, by which it sucks in and throws out the water. SPONGIOSE, in Anatomy, an appellation given to several parts of the body. SPONSORS. See GOD FATHERS. SPONTANEOUS COMBUSTION. Many vegetable sub- stances, highly dried, and heaped together, will heat, scorch, and at last burst into a flame. Of those, the most remarkable is a mixture of the expressed oil of the farinaceous seeds, as rape or linseed oil, with almost any dry vegetable fibre, such as hemp, cotton, matting, &c. and still more so, if also united with lamp-black or any other carbonaceous substance. These mixtures, if kept for a time undisturbed in close bundles, and in a warm temperature, even in small quantities, will often heat and burn with a smothered fire for some hours; and if air be admitted freely, will then burst into flame. To this, without doubt, may be attributed several accidental conflagrations in storehouses, and places where quantities of these substances are kept. - SPONTOON, is a weapon much like a halberd, formerly used instead of a half-pike, by the officers of foot. SPOONDRIFT, a sort of showery sprinkling of the sea- water, swept from the surface of the waves in a tempest, and flying according to the direction of the wind. SPOTS, in Astronomy, dark places observed on the discs of the sun, moon, or planets. These were first discovered by Galileo in the year 1610, soon after he had completed his tele- scope. SPOUT, the name of a trunk for conveying water from off the tops of buildings. Spout, Water, or Water Spout, in Natural History, is an extraordinary elevation of the water at sea, and is very dan- gerous to ships. Its first appearance is in the form of a deep cloud, the upper part of which is white, and the under black. From the lower part of this cloud hangs down a conical tube, its biggest end at the top, which is called the spout. Under this tube the sea appears in a state of boiling agitation; the water rises, and stands as a column or pillar, some yards above the common surface; and from its extremity it spreads around in a kind of smoke. Many instances have occurred where the water has risen when no spout has been visible. Water-spouts generally appear in warm dry weather, and when the sea is calm. This phenomenon is supposed, by some, to be occasioned by electricity, while others ascribe it to the meeting of contrary winds. It is, however, admitted, that water-spouts frequently appear without any indications of an adequate cause. SPRAT, a small fish well known in London and other mar- kets. The usual length is about four or five inches, and the body deep. From its superficial appearance some have erro- . neously thought it to be a young herring. But a minute exa- mination will prove the species to be distinct. SPRAY, the sprinkling or foam of the sea, which is driven from the top of a wave in stormy weather. It differs from the spoondrift, as being only blown occasionally from the broken surface of a high wave; whereas the latter continues to fly horizontally along the sea without intermission during the ex- cess of a tempest or hurricane. It is sometimes called spry. SPRING, in Natural History, a fountain or source of water rising out of the ground. SPRING, in Mechanics, denotes a thin piece of tempered steel, or other elastic substance; which being wound up, serves to put several machines in motion by its elasticity, or endeavour to unbend itself; such is the spring of a clock, watch, &c. SPRING, among Sailors, implies a crack running transversely or obliquely through any part of the mast or yard, so as to ren- der it unsafe to carry the usual quantity of sail thereon SPRING, is also a rope passed out of a ship's stern, and at- tached to a cable proceeding from her bow, when she lies at anchor. It is usually performed to bring the ship's broad side, or battery of cannon, to bear upon some distant object, as an- other ship, a fortress on the coast, &c. When a ship rides by anchors which are only attached to one end, she will move like a weather-cock, according to the direction of the wind or tide. Now, if a rope be extended to the other end to the same anchor, it is evident that by slackening one of these ropes, and keeping the other fast, her side will lie more or less obliquely to the wind or tide as occasion may require, so as to be opposed to any distant object to the right or left. For instance, if a ship ride with her head northerly, and is required to cannonade a fortress lying on the south or south-east, a hawser is, run out of the stern, and being carried forward without her fid, is attached to the cable, at a competent distance ahead of the ship; the haw- ser is then tightened by the capstan or tackles, and the cable being slackened the ship immediately turns her side towards the object intended to be battered. SPRING, is likewise a rope extending diagonally from the stern of one ship to the head of another which lies abreast of her at a short distance, and is performed to make one of the ships sheer off to a greater distance from the other. Springs of this kind are occasionally applied to a wharf or pier for the same purposes. To Spring a Mast, Yard, &c. is to crack it transversely or obliquely. c SPRING Tide, the periodical excess of the elevation and de- pression of the tide, which happens soon after the new and full IOTO OI!. SPRINGS. On the different Properties of Metal and Wooden.— The spring is not only a very useful auxiliary, but an indis- pensable requisite, in many pieces of mechanism. But, from the difficulty of getting springs to stand, as the workmen ex- press it, to their temper, they are not so frequently applied to the purposes of mechanics as otherwise they might be. Great judgment and skill, as every one knows who is conversant with the subject, are required, to give to a metal spring its due de- gree of temper; for, if made too hard, it snaps; if not hard enough, it sets. Metal springs, however, frequently fail from another cause, which is very little understood; in consequence of which, the failure is usually attributed, though, as presently will be seen, unjustly, to the unskilfulness of the workman. It is a circumstance not commonly observed respecting a metal spring, that if it has not something to stop against, but is suf- fered to vibrate after performing the requisite action, it will, in a short space of time, if the action be frequently repeated, either break or set. Whence this property arises, is not at present the object of inquiry. It is mentioned, that, in cases which 956 S Q U s P U DICTIONARY OF MECHANICAL scIENCE. will admit of it, this inconveniency may be guarded against. In those cases in which the vibration cannot conveniently be avoided, a wooden spring, which is not subject to the like in- convenience, is the vbest, and perhaps the only substitute. A wooden spring is, in the property alluded to, the reverse of a metal one : if stopped in its vibration, it soon sets or breaks; if permitted to vibrate, its temper' or elasticity suffers not the smallest diminution. Some years ago, the Reverend Edmund Cartwright established a mill for a manufacturing purpose, (we believe, for weaving by power, which was first introduced by him, and for which he was afterwards rewarded by parlia- ment.) In this mill he had occasion to apply springs, under the circumstances mentioned above; he at first attempted to make use of metal ones, but in vain, being never able to make them stand a single day’s work. He tried every kind of steel, and employed many different workmen, but still without suc- cess. Merely as a temporary expedient, till such time as he could get a fresh supply of steel springs, he one day tried a wooden one, which, to his agreeable surprise, completely an- swered his purpose ; and from that time, as may be concluded, he never used any other than wooden ones. The experiment was perfectly decisive: the springs were in daily action for four years successively, making, in a common way, from forty to fifty strokes in a minute, on an average. At the expiration of the four years, those springs which had escaped accidents were as elastic, and as strong, as when first put into action. The wood they were made of was red deal, clean grained, and per- fectly free from knots. To many manufacturers who employ machinery for various purposes, in which springs, that must be suffered to vibrate, form a part, this information, which may to some appear trivial, will be found highly useful. * SPRINGES, a sort of noose made of horse-hair, and some- times spread on the ground, supported by a twisted willow, to ensnare birds. Springes are, however, used in various other ways, being occasionally set in hedges, on the boughs of trees, and in other places to which birds resort. SPRIT, a small boom or pole, which crosses the sail of a boat diagonally from the mast to the upper aftmost corner, which it is used to extend and elevate ; the lower end of the sprit rests in a sort of wreath, called the snotter, which encir- cles the mast at that place. ingly called sprit-sails. SpRit Sail, is also a sail attached to a yard which hangs under the bowsprit. It is furnished with a large hole towards each of its four corners, to evacuate the water with which the cavity or belly of it is frequently filled by the surge of the sea, when the ship pitches. SPRIT Sail Top-sail, a sail extended above the former by a yard which hangs under the jib-boom ; the clues of this sail are hauled home to the sprit-sail yard arms, after which the sail is drawn out towards the extremity of the boom, as any other top-sail yard is hoisted upon its mast. Formerly, the sprit-sail top-sails were set on a mast which was erected perpendicularly on the end of the bowsprit, but this method has of late been justly rejected as inconvenient and dangerous to the bowsprit, although serviceable in light breezes. - f SPRIT Sail Top-gallant Sail, is set upon the flying jib-boom, in the same manner that the sprit-sail top-sail is set upon the inner jib-boom ; this sail is, however, very rarely used. SPROUT, the common name of a young shoot, offset, or sucker, which is thrown out by the parent plant or tree. SPRUCE-BEER, a cheap and wholesome liquor, which is thus made : Take of water sixteen gallons, and boil the half of it. Put the water thus boiled, while in full heat, to the cold part, which should be previously put into a barrel, or other ves- sel; then add sixteen pounds of treacle or molasses, with a few table-spoonfuls of the essence of spruce, stirring the whole well together; add half a pint of yeast, and keep it in a temperate situation, with the bung-hole open for two days, till the fer- mentation is abated. Then close it up, or bottle it off, and it will be fit for being drunk in a few days afterwards. SPUNGE, an instrument used to clean the cannon after firing, and to extinguish any sparks that may remain behind. They are sometimes made of bristles resembling a round brush, but more generally of sheep-skin with the wool outwards, nailed upon a block of wood nearly as large as the caliber of the piece These kind of sails are accord- Squall, produces no such diminution. The block is either fixed upon a long wooden staff, or upon a ihick piece of rope, well stiffened by serving it with spun yarn. This latter is much more convenient on board of ships, on ac- count of its flexibility ; and is generally furnished with a block at the upper end, to use as a rammer. To spunge a gun, is to clean it out with the sponge; and should be constantly repeated after every explosion. - .# * : * : SPUNGE, or Spong E, a marine substance found adhering to rocks, shells, &c. under cover of the sea-water, or on the sides. of rocks regularly visited by the tides. It was long disputed. whether this production of nature belonged to the mineral, the vegetable, or the animal kingdom; but it is now ascertained to be of animal origin, being the fabric and habitation of some species of worm or polype. - - SPUN-YARN, a small line or cord formed of two, three, or more rope-yarns, twisted together by a winch; the yarns are usually drawn out of the strands of old cables and knotted to- gether. Spun-yarn is used for various purposes, as seizing and serving-ropes, weaving mats, &c. * SPUR, a piece of metal, consisting of two branches encom- passing a horseman's heel, and a rowel, in form of a star, ad- vancing out behind to prick the horse. % - - SPY, a person hired to watch the actions, motions, &c. of another, particularly of what passes in a camp. When a spy. is discovered he is hanged immediately. SQUACCO, a large bird of the heron kind, that is bold and fierce. Its head is adorned with a crest of black, white, and yellow ; and its plumage is variegated throughout with the same tintS. . r - SQUAD, in Military language, denotes a small number of horse or foot, collected for the purpose of exercise. - SøUAD, Awkward, consists of such recruits, and others, as . cannot go regularly through their military evolutions. It is frequently used as a term of reproach to such officers and men as are deficient in their duty. º SQUADRON, in Military Affairs, denotes a body of horse, whose number of men is not fixed, but is usually from one to two hundred. Each squadron usually consists of three troops of fifty men each.-SQUADRON, in Naval Affairs, either implies a detachment of ships employed on any particular expedition, or one-third part of a naval armament. - SQUALL, a sudden and violent gust of wind, usually occa- sioned by the interruption and reverberation of the wind from high mountains. These are very frequent in the Mediterranean, particularly that part of it which is known by the name of the Levant, as produced by the repulsion and new direction which the wind meets with in its passage between the various islands of the Archipelago. - A Black SQUALL, one attended with a dark cloud, which oc- casions a diminution of the usual quantity of light. A White A Thick Squall, is ac- companied with rain, sleet, &c. SQUALUS, the Shark, in Natural History, a genus of fishes of the order cartilaginei. These animals are never found in rivers or lakes, inhabiting only the sea, and carrying terror and destruction wherever they appear. They grow in some species to the weight of three or four thousand pounds. They occa- sionally emit a phosphoric illumination, visible by night. They produce their young alive, several at a birth, but every one enclosed in a transparent hornlike substance, lengthened at the extremity into a thread which attaches to fixed substances, such as rocks or weeds. Some appear to live on vegetables chiefly, but the greater number are rapacious of animal sub- stances in the extreme. They seize, indeed, whatever they find, with the most violent avidity, following in the wakes of ships, for the sake of nearly every thing thrown from them, and are fatal to those mariners who slip from their hold on the rigging. into the sea, in which case the sharks are seen to tear them to pieces, with all the violence of competition. They are in most instances solitary wanderers through the ocean, but in some species they are gregarious. They contain large quantities of oil, and their skin is convertible to several useful purposes. SQUARE, among Sailors, is a term peculiarly appropriated to the yards and their sails, either implying that they are at . right angles with the mast or keel, or that they are of greater extent than usual. Thus, when the yards hang at right angles. S T A S T A 95.7 DICTIONARY OF MECHANICAL SCIENCE. with the mast, they are said to be square by the lifts; when they hang perpendicular to the ship's length, they are called square by the braces; but when they lie in a direction perpen- dicular to the plane of the keel, they are square by the lifts and braces; or, in other words, they hang directly across the ship, and parallel to the horizon. The yards are said to be very square, when they are of extraordinary length, and the same epithet is applied to their sails with respect to their breadth. SQUARe-rigged, is a vessel used in contradistinction to all vessels whose sails are extended by stays, lateen, or lug-sail yards, or by gaffs and booms, the usual situation of which is nearly in a plane with the keel. . SQUARE Sail, is any sail extended to a yard suspended by the middle, and hanging parallel to the horizon, as distinguished from other sails which are extended obliquely. Square Sail, is also the name of a sloop's or cutter's sail, which hauls out to the lower yard, called the square-sail yard. This sail is only used in fair winds, or to scud in a tempest. In the former case it is furnished with a large additional part called the bonnet, which is then attached to its bottom, and removed when it is necessary to scud. SQUARE. See GeoMetRY. - f SQUARE NUMBER, the product of a number multiplied into itself. * - SQUARE, in the Military Art, a particular formation into which troops are thrown on critical occasions particularly to re- sist the charge of cavalry. - SQUARE Solid, is a body of foot, where both ranks and files are equal. It was formerly held in great esteem ; but when the prince of Nassau introduced the hollow square, this was soon neglected. • SQUARE, Hollow, is a body of foot drawn up, with an empty space in the centre, for the colours, drums, and baggage facing every way, to resist the charge of the horse. SQUARe, Oblong, a square which is not at right angles, but represents the figure of an oblong, whose sides are unequal. SQUARE, Perfect, a square whose sides are equal and at right angles. - - SQUILL, or Sea ONIon, in the Materia Medica. The roots, or rather the bulbs, of this species, are the parts that are used in medicine. There are two sorts, the white and the red. but the latter is generally preferred. Squills grow naturally on sea-shores, or in ditches to which salt water has access. From Spain and the Levant, large quantities are annually imported into England. - , - * SQUINTING, an irregular position and motion of the eyes, in which their axes do not converge to the object looked at. SQUIRREL, a small animal well known in England, and in most other warm or temperate climates, where woods abound. I)uring the summer it provides for the contingencies of winter, by laying up a store of nuts and other fruits. Its tail is formed chiefly of bushy hair, and being nearly as large as its body, serves it in some measure instead of wings, when darting from one tree to another, or even descending to the ground. Of the English squirrel the flesh is said to be delicate, and of an ex- cellent flavour. . STABLE, a building constructed for horses and other ani- mals, being furnished with stalls, and proper contrivances to contain their food and necessary equipments. STACK, a quantity of corn, hay, pease, pulse, straw, or stub- ble, regularly piled up and thatched, to protect it from the in- clemencies of the weather. Various forms prevail in different districts, and the dimensions are regulated by local circum- Stances. . STADIUM, an ancient Greek long measure, about a furlong. g STAFF, among Seamen, a light pole erected in different parts of a ship, whereon to hoist and display the colours. The Ensign Staff, is reared immediately over the stern, to display the ensign. The Jack Staff is fixed at the end of the bowsprit, to extend the jack. A Flag Staff, is erected at each of the mast- ends, or formed by their upper ends to support the flag or pendant of the respective squadron or division to which the ship belongs. STAG, the Red Deer, or Hart. STAGE, among Ship-carpenters, is a machine composed of planks, let over the sides by ropes, whereon the people may stand - when repairing, caulking, or paying the ship's sides, \ 101-2. wales, &c. A Floating Stage, is one which needs not the sup- port of ropes, being sufficiently large and firm to bear upon the water. - - STAGGERS, a disease in horses, nearly allied to apoplexy in human beings. It consists of a giddiness in the head, and is sometimes indicated by madness. - STAIRCASE, an ascent enclosed between two walls,for a balustrade, consisting of steps or stairs, with landing places and rails; serving to make a communication between the several stories of a house. - STALACTITAE, or STALACTAGNIA, stony concretions resem- bling icicles, in Natural History; or crystalline spars formed into oblong, conical, round, or irregular bodies, composed of various crusts, and usually found hanging. in form of icicles from the roofs of grottoes. - - STALK, that part of a plant which rises immediately ſrom the root, and supports the leaves, flowers, and fruits. STAMINA, in the animal body, are defined to be those simple original parts, which existed first in the embryo. STAMMERING, a hesitation in pronunciation, or inter- ruption of speech, which seems generally to arise from fear, eagerness, or some violent passion. This should be checked as much as possible in its early stages, by slow and deliberate pronunciation; for once confirmed into a habit, it becomes inveterate." . STAMP DUTies, a tax imposed upon all parchment and paper on which any legal proceedings are written; and also upon licenses for retailing wines; upon all almanacks, news- papers, advertisements, cards, dice, and pamphlets of a certain description. STAMPs, in Metallurgy, large heads of iron fastened to tim- bers that are lifted by the revolution of a water wheel. These falling on the ore that is incorporated with refuse, beat the whole to powder, that the valuable parts may be separated from the useless, and preserved. - STANCHIONS, those pillars which being set up pillar-wise, support and strengthen the waste-trees, but are chiefly intended to support the weight of the artillery. They are used for various purposes. STANCHIONS of the Nettings, are either slender bars of iron whose lower ends are fixed in iron sockets at proper distances, ja square wooden pillars let into the upper part of the ship's S10 €. . . 2 STANDARD, in Ship-building, is an inverted knee, placed upon the deck instead of beneath it, and having its vertical branch pointed upwards from that which lies horizontally. Royal STANDARD, a flag in which the imperial ensigns of England, Scotland, and Ireland, are quartered, together with the armorial bearings of Hanover. It is never hoisted unless when the king is on board, at which time it is displayed at the main-top-gallant-mast head. - . . STANDARD, in Commerce, the original of a weight, measure, or coin, committed to the keeping of a magistrate, or de- posited in some public place, to regulate, adjust, and try the weights used by particular persons in traffic. STANDARD, in Military affairs, a measure by which men en- listed into his majesty's service have the regulated height ascertained. • STANDARD, in War, a sort of banner or flag, borne as a sig- nal for the joining together of several troops belonging to the same body. - STANDING, in the Sea Language. Standing part of the sheet, is that part of it which is made fast to a ring at the ship's quarter. Standing part of a tackle, is the end of the rope where the block is fastened. Standing ropes, are those which do not run in any block, but are set tawt or let slack as occasion serves, as the sheet-stays, back-stays, or the like. STANNARIES, certain laws to which those who dig and purify tin in the counties of Cornwall and Devonshire are sub- ject. There are four stannary courts for each of the above counties, to which appeals are made by the tinners, and in which justice is administered by the lord and vice-wardens, who preside. An appeal lies from these courts to the privy council of the princé of Wales, as duke of Cornwall, and thence, finally, to the king himself. - STANZA, in Poetry, a certain stated number of gravo 11 L, 958 S T. A . S. T A DICTIONARY OF MECHANICAL. SCIENCE- verses, containing a perfect sense, and terminated with some significant pause. . . . . . . . . . . . . . . . . . . . .3 STAPLE, primarily signifies a public place or market, whi- ther merchants, &c. are obliged to bring their goods to be bought by the people, as the Greve, or the places along the Seine, for sale of wines and corn at Paris, whither the mer- chants of other parts are obliged to bring those commodities. Formerly the merchants of England were o' 'iged to carry their wool, cloth, lead, and other like staple ommodities of this realm, in order to utter the same by. wuulesale, and these sta- pies were appointed to be constantly kept it York, Lincoln, New- castle upon Tyne, Norwich, Westminster Canterbury, Chiches- ter, Winchester, Exeter, and Bristol; in each whereof a public mart was appointed to be kept, and each of them had a court of the mayor of the staple, for deciding differences held ac- cording to the law-merchant, in a summary way. The Staple commodities of this kingdom are said by some to be these, viz. wool, leather, wool-felts, lead, tin, butter, cheese, cloth, &c. but others allow only the first five to be staple commodities. ; STARLING of Wool, the art or process of adjusting the i qualities and different properties of wool in the same fleece, selecting the fine from the coarse, and placing together the more valuable parts. This is frequently called sorting. STAR, in Astronomy, a general name for all the heavenly bo- dies, which are dispersed through the whole heavens. . . . . is a meeting in every hundred of all the shires in England, StARs, Falling, in Meteorology, meteors which dart through the sky in the form of a star. - STAR, in Pyrotechny, a composition of combustible matters, ſ t which being thrown aloft in the air, exhibits the appearance of: a real star. . • * - - - - STAR Shot, a gelatinous substance frequently found in fields, and is the half-digested food of herons, sea-mews, and the like birds; for these birds when shot have been found to disgorge a substance of the same kind. STARBOARD, the right side of a ship when the eye of a spectator is directed forward. - STARBOARD, is also an order to the helmsman to put the helm a little to the starboard side ; is going large or free. - . . - STARCH. If a quantity of wheat-flour be formed into a paste, and then put under a very small stream of water, stir- ring it continually, till the water runs off from it colourless, the flour by this process is divided into two distinct constituents. A tough substance of a dirty white colour, called gluten, remains in the hand; the water is at first milky, but soon deposits a white powder, which is known by the name of starch. STARLING, in Ornithology, a bird about the size of the common blackbird. The whole plumage is a resplendent black, with changeable blue, purple, copper, tints of green, and small yellow spots. During winter they assemble in large flocks. ennant says, they may be taught to speak; and Ray observes, that they imitate the human voice much better than the parrot. STATE, an empire, kingdom, province, or extent of country, under the same government. - STATICE, in Botany, a name now applied to the common thrift, or sea gilliflower. - STATICS, that branch of mathematics which considers the motion of bodies arising from gravity. ! . . STATION BILL, a list containing the appointed posts of the ship's company when navigating the ship. STATIONARY, in Astronomy, the state of a planet when it seems to remain immoveable in the same point of the zodiac. STATIONERS. This denomination of venders of books, paper, &c. is derived from the following circumstance. The traffic of books was anciently very inconsiderable, in so much that the book merchants of England, France, and Spain, and other countries, were distinguished by the appellation of Sta- tioners, as having no shops, but only stalls and stands in the Streets. • STATISTICS, a word lately introduced to express a view of survey of any kingdom, county, or parish. : - STATUARY, a branch of sculpture, employed in the making of statues. In this art the ancients are thought to have ex- celled the moderns. Among the former, the name of Phidias stands pre-eminent; and among the latter, that of Michael Angelo. . . . - * * .* º and is used only when the ship | stay. STATUES, are figures representing living or deceased crea- tures, of whatever species, real of imaginary; and carved, cast, modelled, or moulded, in full relievo, insulated on every part. Statues are formed with the chisel, of several materials, such as marble, stone, &c.; they are carved in wood, or cast in plaster of Paris, or other matter of the same nature; they are also cast in several metals, as lead, brass, silver, and gold. . STATURE, the height or pitch of a man, which is found admirably adapted to the circumstances of his existence, STATUTE, in its general sense, signifies a law, ordinance, decree,. &c. Statute, in our laws and customs, more immedi. ately signifies an act of parliament made by the three estates of the realm ; and such statutes are either public, of which the courts at Westminster must take notice, without pleading them, or they are special and private, which last mnst be pleaded. STATUte Merchant, is a bond of record acknowledged before one of the clerks of the statute merchant, and lord mavor of the city of London, or two merchants of the said city for that pur. pose assigned, or before the mayor or warden of the town, or other discreet men, for that purpose assigned. - * STATUTE Staple, is a bond of record acknowledged before the mayor of the staple, in the presence of all or one of the con- i stables; but now statute staple, as well as statute merchant, are in great measure become obsolete. $ * STATUTEs, or Statute Sessions, otherwise called petit sessions, | whereto the constables and others, both holder and servants, repair for the debating of conferences between masters and ser- vants, the rating of servants' wages, and bestowing such people in service as, being fit to serve, either refuse to seek or get masters. STAUROLITE, in Mineralogy. This stone has been found at Andresberg in the Hartz. It is crystallized, and the form of its crystals has induced mineralogists to give it the name of cross-stone. Its crystals are two four-sided flattened prisms, terminated by four-sided pyramids, intersecting each other at : right angles ; the plane of intersection passing longitudinally through the prism. Sometimes these prisms occur solitary. Primitive form, an ogtahedron with isosceles triangular faces, the faces of the crystals striated longitudinally. STAVE, in Music, the five horizontal and parallel lines on and between which the notes are placed. . . . . STAY, a large strong rope, employed to support the mast on the fore part, by extending from its upper end towards the stem of the ship, as the shrouds are extended on each side. The Fore Stay, is that which reaches from the fore-mast head towards the bowsprit end. The Main Stay, is that which extends to the ship's stem. The Mizzen Stay, is that which is stretched to a collar on the main-mast immediately above the quarter-deck. The Fore Top-Mast Stay, is that which comes to the end of the bowsprit, a little beyond the fore-stay. The Main-Top-Mast Stay, is attached to the hounds of the fore-mast. The Mizzen Top-Mast Stay, is that which comes to the bounds of the main- mast. The Fore-Top-Gallant Stay, is that which comes to the outer end of the jib-boom. The Main-Top-Gallant Stay, is that which is extended to the head of the fore-top-mast. The Mizzen- 'op-Gallant Stay, is that which is attached to the head of the main-mast. The Royal-Stays, when used, are those which ex- tend to the jib-boom end, or to the heads of the top, or top-gal- lant masts next before them. The whole of these stays are nearly in the direction of the upper edges of the several stay- sails which derive their names from them. - - SPRING STAY, is a kind of assistant stay, extending in a direction nearly parallel to the principal stay, it is much thinner than the other, and is only used to the lower-masts and top- maStS. - - STAY-Sail, any sail extended upon a stay. STAY-Sail-Stay, a rope used solely to extend and support á stay-sail, as the middle stay-sail. . . STAY-Tackle, a large tackle, attached by means of a pendant to the main-stay. It is used to hoist heavy bodies, such as the boats, or butts of water, beer, &c. in or out of the ship, and out of the holds; for which purpose there are generally two. the one over the fore-hatchway, the other perpendicular to the main- hatchway; and they are accordingly distinguished by the epi- thets, main or fore stay-tackles, though both are upon the main- st E s T E 953 Diction ARY of MECHANICAL scIENCE. STEADY, at Sea, the command given to the helmsman in a hand, water which is retained in a close vessel, under a greater fair wind, to steer the ship in the line on which she advances at that instant, without deviating from the right or left; to which the helmsman answers, “Steady,” to shew his attention to the order. , * * * ' . - STEALING, the fraudulent taking away another man's goods, with an intent to steal them against, or without, the will of him whose goods they are. - * STEAM, water converted by heat into vapour. produced from water or other liquids in a state of ebuilition. General Principle of the Steam Engine.—The force of the steam-engine is derived from the property of water to expand itself in an amazing degree, when heated above the tempera- ture at which it becomes changed into steam or vapour, which being an exceedingly elastic fluid, it can be retained within the close vessel or boiler to which the heat is applied, even when it has an expansive force sufficient to make it fill, if left at liberty, 20 or 30 times the space in which it is confined. In this state the steam will exert a proportionate force or pressure to burst open the sides of the vessel in which it is retained; which force may be applied either to expel or raise up water from any ves- sel into which the confined steam is admitted, or to give motion to a moveable piston, which is so accurately fitted to the interior capacity of such vessel, as not to permit the escape of the steam ‘between them. º - - Another source of the power of the steam engine, is the faci- lity with which steam of a great expansive force can be cooled by the application of cold water, and condensed into the small Quantity of water from which it was originally produced. A partial vacuum can thus be made, in a very large vessel, in an . instant, and even in the same vessel, which was, a moment before, filled with confined steam, exerting a great force to escape. The pressure of the atmosphere which tends to fill up this vacuum, can be made to produce the ascent of water into the vessel to any height less than twenty-four or twenty-five feet. Or the pressure of the atmosphere may be made to give motion to a piston, by admitting the atmospheric air to press upon one side of the piston, whilst there is a vacuous space formed by the condensation of the steam which filled the cylin- der on the other. . Notwithstanding the great variety of different constructions of the steam-engine, they all derive their force from one of these two principles, or from the combination of the two ; but before entering upon any description of the manner in which these forces are applied, it is necessary to have clear ideas of the nature of steam, and of the law by which it expands by heat, in order to form a precise judgment of what passes in the interior part of a steam-engine when it is at work. In the com- mon acceptation of the word steam, it is that hot white vapour which we see every day rising in a cloud from a tea-kettle, or a boiling pot: but this is not exactly the state of the steam employed in an engine; it is there perfectly transparent, and is more or less hot than boiling water, according as it is retained under a lesser or greater degree of compressure. pressure of the atmosphere, bearing upon the surface of the water, will retain it in a state of fluidity, until it is heated to what is generally called the boiling point, and is marked 2129 in Fahrenheit's thermometer. If the heat is increased above that degree, and if the water is unconfined except by the pressure of the atmosphere, the water immediately assumes the aeriform State, and flies off in elastic vapour, which we call steam ; but if the same water is relieved from the pressure of the atmo- sphere by enclosing it in a close vessel, and exhausting the air from it, a certain portion of steam or vapour will rise from the same at any temperature, even when it is as low as freezing; and if this vapour is conveyed off from the vessel as fast as it rises, the water, although cold, will boil, and such vapour will rise as fast as from the boiling kettle in the open air. If the vafour is retained in the vessel, it will only accumulate, until it has acquired a certain degree of elastic force to press upon the surface of the water, which will then cease to yield any more vapour, until the heat is farther increased, or that the vapour is drawn off to relieve the water from the pressure which confined and retained it in its fluid state. On the other The ordinary degree of pressure than that occasioned by the pressure of the atmosphere, will not boil or rise in vapour, until it becomes heated to a higher temperature than 212°. It is even probable, that water might be compressed to that degree, that it would not boil until heated red-hot ; but this would require such aſ enormous strength in the vessel which should contain the steam, that it is far beyond the practicability of an experiment. In ; - this manner the reader is to bear in mind, that vapour or steam, STEAM-ENGINE, an engine originally contrived for raising water by means of the expansive force of the steam or vapour in | other words, that the temperature of the steam is an exact index of the elastic or expansive force with which it presses when confined in close vessels, is always more or less elastic, in proportion to the degree of heat which is applied to it; or, in upon the surface of the water, and against the interior surface of the vessel which contains it. - - - The first notice which we have of the steam-engine, is in a small pamphlet by the Marquis of Worcester, written in 1655, and published during the reign of Charles II. in 1663, entitled, “A Century of the Names and Scantlings of the Marquis of Wor- cester's Inventions.” In the sixty-eighth article of this Century of Inventions, the author thus speaks:– “An admirable and most forcible way to drive up water by fire not by drawing of sucking it upwards, for that must be as the philosopher calleth it, intra spheram activitatis, which is but at such a distance. But this way hath no bounder, if the vessel be strong enough: for I have taken a piece of a whole cannon, whereof the end was burst, and filled it three-quarters full of water, stopping ‘and screwing up the broken end, as also the touch-hole; and making a constant fire under it, within twenty-four hours it burst, and made a great crack; so that having a way to make my vessels, so that they are strengthened by the force within them, and the one to fill after the other, I have seen the water run like a constant fountain stream forty feet high ; one vessel of water, rarefied by fire, driveth up forty of cold water. And a man that tends the work is but to turn two cocks, that one vessel of water being consumed, another begins to force and refill with cold water, and so successively; the fire being tended and kept constant, which the self-same person may likewise abundantly perform in the interim between the neces- sity of turning the said cocks.” However plain these hints may now appear, they were thought at the time when first published, to border so much on the marvellous and romantic, as to be scarcely worthy of notice; and finally, from being neglected, they became nearly forgotten. At length, after a lapse of about forty years, Capt. Thomas Savery, a commissioner of sick and wounded, obtained a patent in 1698, for “A new invention for raising water, and occasioning motion to all sorts of millwork, by the impellent force of fire.” Of this contrivance, a small model was exhibited to the Royal Society, and in vol. xxi. of their Transactions, their approbation is recorded. The inventor afterwards pub- lished an account of his engine in a small book, entitled, “The Miner's Friend,” accompanied with an engraving ; which shews that this early effort of genius had made a bold advance toward perfection. - It appears from Captain Savery’s description, that his engine not only derived its power from the expansive force of steam, like that of the Marquis, but also by the condensation of steam, the water being first raised by the pressure of the atmosphere, to a given height from the well into the engine, and then forced out of the engine up the remaining height, by the expansive force of steam. This action was performed alternately by two receivers, so that while the vacuum formed in one, was draw- ing up from the well, the pressure of the steam in the other was forcing up water into the reservoir. The power and utility of Savery’s engine being every where acknowledged, many im- provements were subsequently made by various engineers, in its appendages, arrangements, and the adjustments of its parts; but nothing of importance appeared, to mark an era in the history of the steam-engine, until about the year 1705, when Thomas Newcomen, ironmonger, and John Cawley, glazier, of Dartmouth, obtained a patent for a new invention; but so far was their principle of movement connected with that of Savery, that the latter was admitted to a participation in their patent. The engine thus brought into use is sometimes called the atmospheric engine, and is commonly a forcing pump, having 960 S T E s T E DICTIONARY OF MECHANICAL scIENCE. its rod fixed to one end of a lever, which is worked by the weight of the atmosphere upon a piston at the other end, a temporary vacuum being made below it by suddenly condensing the steam that had been admitted into the cylinder in which this piston works, by a jet of cold water thrown into it. A partial vacuum being thus made, the weight of the atmosphere presses down the piston, and raises the other end of the straight lever, toge- ther with the water, from the well. Then immediately a hole is uncovered in the bottom of the cylinder, by which a fresh quantity of hot steam rushes in from a boiler of water below it, which proving a counterbalance for the atmosphere above the piston, the weight of the pump-rods, at the other end of the lever, carries that end down, and raises the piston of the steam- cylinder. The steam hole is then immediately shut, and a cock opened for injecting the cold water into the cylinder of steam, which condenses it to water again, and thus making a vacuum below the piston, the atmosphere again presses it down, and raises the pump-rods as before ; and so on continually. On this engine some considerable improvements were after- wards made by Mr. Smeaton, which though containing little that was new in principle, tended much to facilitate the pro- gress of this mighty agent in the mechanic arts. . The improve- ments made by Watt upon the engine of Newcomen and Cawley are first, that the elasticity of the steam itself is used as the ac- tive power in this engine; and secondly, that besides various other judicious arrangements for the economy of heat, he con- denses the steam, not in the cylinder, but in a separate vessel. In the cylinder or syringe, concerning which we have spoken, in mentioning the engine of Newcomen, let us suppose the up- per part to be closed, and the piston rod to slide air tight through a collar of leathers. In this situation it is evident that the piston might be depressed by throwing the steam upon its upper surface, through an aperture at the superior end of the cylinder. But if we suppose the external air to have access to the lower surface of the piston, we shall find that steam no stronger in its elasticity than to equal the weight of the atmo- sphere would not move the piston at all ; and consequently that this new engine would require much denser steam, and consume much more fuel, than the old engine. The remedy for this evil is to maintain a constant vacuum beneath the piston. If such a vacuum were originally produced by steam, it is certain that its permanency could not be depended on, unless the engine contained a provision for constantly keeping it up. Watt’s contrivance in his simplest engine is as follows:—The steam is conveyed from the boiler to the upper part of the cylinder through a pipe, which also communicates occasionally with the lower part, and beyond that space with a vessel immersed in a trough of water; in which vessel the condensation is performed by an injected stream of cold water. This water is drawn off, not by an eduction pipe but by a pump, of which the stroke is sufficiently capacious to leave room for the elastic fluid, sepa- rated during the injection, to follow and be carried out with the injection water. Suppose now the piston to be at its greatest elevation, and the communication from the boiler to the upper as well as to the lower parts of the cylinder to be opened. The steam, under these circumstances, will pass into the whole internal part of the engine, and will drive the air downwards into the condenser, and thence through the valves of the air. pump. In this situation, if the communication from the boiler to the lower part of the cylinder be stopped, and an injection be made into the condenser, a vacuum will be produced in that vessel, and the steam contained in the lower part of the cylin- der and communication pipe will expand itself with wonderful rapidity towards the condenser, so that in a period of time too minute to be appreciated, the whole of the steam beneath the piston will be practically condensed. The steam which con- tinues to act above the piston will immediately depress it into the vacuum beneath; at the same time that by connexion with the external apparatus, the piston of the air pump also descends in its barrel. When the stroke is nearly completed downwards, the requisite part of the apparatus shuts the communication with the boiler, opens that between the upper and lower parts of the cylinder and condensing vessel, and turns the injection- cock. At this very instant the piston loses its tendency to descend, because the steam presses equally on both surfaces, and continues its equality of pressure while the condensation is performed. It therefore rises; the injection is stopped; and the air-pump making its stroke suffers the injestion water and a considerable part of the elastic fluid to pass through its lower valve. The vacuum is thus kept up through the whole internal capacity of the engine. As soon as the piston has reached the upper part of the cylinder, the communication to the under part of the cylinder is stopped, and that with the boiler opened, as before ; the consequence of which is, that the piston again descends; and in this manner the alternations repeatedly take place. The principal augmentation of power in this engine, compared with that of Newcomen, arises from the cylinder not being cooled by the injection water, from its being practicable to use steam, which is more powerful than the pressure of the atmosphere, and from the employing of this steam both to elevate and to depress the piston. In general, these engines are worked by steam, which would support a column of four or five inches of mercury besides the pressure of the atmosphere, and sometimes more. All the engines which were constructed before the time of Mr. Watt were employed merely for raising water, and were never used as the first movers of machinery; except indeed, that Mr. R. Fitzgerald published in the Transactions of the Royal Society, a method of converting the irregular motion of the beam into a continued rotatory motion, by means of a crank and a train of wheel-work connected with a large and massy fly, which by accumulating the pressure of the machine during the working stroke, urged round the machinery during the returning stroke, when there is no force pressing it forward. For this new and ingenious contrivance, Mr. Fitzgerald received a patent, and proposed to apply the steam engine as the moving power of every kind of machinery; but it does not appear that any mills were erected under this patent. In order to convert the reci- procating motion of the beam into a circular motion, Mr. Watt has a contrivance far more simple, as may be seen by inspect- ing any of the numerous engravings of his machinery. The strides which steam is making in the economy of the coun- try, are more gigantic and surprising than those who are domes- ticated at a distance from its immediate operation imagine; but the capability of the locomotive engine to travel, with ease and safety, with a weight of ninety tons in its train, at the rate of eight miles an hour, having been proved by the opening of the Darlington and Stockton rail-road, the following particulars of its powers and advantages may not be unacceptable to the reader:-The engine will travel over 25 miles seven times a day, making 175 miles a day’s work, with 90 tons, consuming seven tons of small coals each day, or 42 tons per week; which, at an average cost of 7s., £14. 14s. will be the expense. One man and a boy in constant attendance, supposing the 24 hours equal to three days, will be three men and thirteen boys each day, at 16s. 6d. ; this will add £5. 3s. 6d. making the total weekly expense £19. 17s.6d. The engine will cost £600, 80 waggons £900,—giving £1500 for the entire set out.. Now, 90 tons will load six boats, each of these boats will be a day in performing 20 miles; therefore 52 boats, with 52 horses, 52 men, and 52 boys, will be required to execute the transfer of 90 tons 175 miles in one day. Each horse will cost weekly one guinea, each man a guinea, and each boy 12s. forming a total weekly charge of £140. 8s. in lieu of £19. 17s.6d. The 52 boats and horses will be worth £10,000, and requiring a considerably greater amount to keep them in repair, throwing a balance of full £7000 per annum in favour of every locomotive engine that may be used. How many may eventually be at work, it would be difficult to conjecture; but as forty would be required to work the London, Birmingham, and Liverpool, and the Man- chester and Stockport lines, in all probability not less than 500 would be employed; and as the saving on every five engines would be equal to the interest of one million, the 500 would put the people yearly in possession of a sum as great as the interest of one hundred millions sterling, independently of the advantage of speed, and of the great saving of tonnage, the rail-road lines being one-third shorter than the canals in use. Finally, 1000 persons may be conveyed one mile, or one person 1000 miles, by locomotive engines, at the rate of eight miles an hour, at a cost of something less than five pence. In addition to the improvements made by Watt on his original invention, many others are highly deserving of notice; but the |- |- ſzºt 6 nºi （outro， torreu ： ， tros aestu un caenae zaer） -------- ---- |-----| _ _ ·|- ·× × × × ×F7F7F7F2F（~~~~）;|-|-·ſr ： ： ~~~~ ~~|ſaeae aer |-|-|||||||||||||||| ·| ſl | …|- ·|- h = | ſ= غ__ 01 º ！ 5 ---- |- |- |-|-|- | || |||- |- ¿） ſ£ |-º -： - -".…………_ _ ·|-----|-|-|×） .----|--^, … |-|-- ，，，,© ^^^%，^^^^^^^^^^^^/ º^^^%, , ºſ^2·^^^|-|-Z.^^^^^^^^^^^^^^^^/…/ - |-|-， º %~ º.//%%·Z， Ź,^^^Z/^^Ø/ · . . . .|-- ---- - -|- - . ^º^.^81，0 el sºlis （IOIHI EI „IO GINIĘ)， №I）. º/ z/ / /* º/º, º/, 2. º 2// º 4% Aſ O ZZ "O.A. A/º/, º, ** Pºe. N ------ S T E S ‘i’ E 961. DICTIONARY OF MECHANICAL SCIENCE. # whole are too numerous to admit in detail. During the last twenty years, scarcely a month has elapsed in which some new modification has not been proposed, among which, several have been found highly beneficial. The names of Witty, Bettan- court, Moyle, Trevithick, Woolf, Evans, Perkins, and others, will never be forgotten while the steam-engine is remembered, and shall retain its use; but their respective merits we cannot find room to enumerate. * - Of the steam-engine described in the following paragraphs, and illustrated in the plates, we have been furnished with an account by Mr. Hick, whose name it bears:— “Twelve Horse Portable Steam-Engine, as manufactured by Rothwell, Hick, and Rothwell, engineers, Bolton, Lancashire. Steam cylinder 19% inches diameter; 4 foot stroke; 27 strokes in a minute. “This engine consists, in the first place, of a large cast iron plate, firmly bolted down to stone or brick work, on which the whole of the materials are fixed. The beam, with all its appen- dages, is by this means supported without being at all con- nected with the building, by a double diagonal frame, one half only of which can be seen in the drawing. These frames are surmounted by an entablature plate, to which the bearers or spring beams are attached that receive the studs or centers of the radius rods of the parallel motion, the extreme ends of which are supported by a pillar resting on a bracket projecting from the back of the cylinder. The pedestals in which the gudgeon of the beam works, rest on the entablature plate, and are firmly secured by bolts passing through the whole. The side walls on which the foundation plate acts, are so far asunder as to allow a sufficiently wide recess to receive the condensing cistern, with its air-pump and condenser, hot and cold water pumps, as well as to afford room for getting down to secure the ends of the bolts. The governor is supported by a standard placed directly over the crank shaft, and is turned by a single pair of bevel wheels. The upper part of it is hollow, to receive a small rod that is attached by a cross pin to a brass sliding socket, which is connected with the governor arms by two small links, and partakes of the raotion communicated to them by the movement of the balls. The small rod has a communi- cation with the throttle valves, by means of the levers fixed to the ceiling of the engine-house. g “The annexed engraving represents a steam-engine of twelve horses’ power, with a cross section of its boiler A, about two-thirds filled with water. The boiler is oblong, 12 feet by 5% feet, and the flame, after acting upon the whole length of the bottom, is conducted entirely over the whole surface of the sides and ends, by means of the brick ſlues, (which are wide enough to admit a person to get in, to clean them when requisite,) before its entrance to the chimney. “In the ſlue near to the chimney, is placed a damper or plate, moving perpendicularly in two grooves, in such a manner as entirely to stop the draft when shut. This damper is suspended by a chain passing over two pulleys, at the opposite end of which is attached a hollow iron float, that moves up or down in a pipe fixed on the top of the boiler, exactly in proportion to the height of the column of water in the pipe, that the strength of the steam is capable of supporting, which rising in height as the strength of the steam increases, raises the float, and causes the damper to descend, thereby lessening the draft, and vice versa. To this apparatus a bell is sometimes connected, to give notice of the time when it is necessary to throw an addi- tional quantity of coals upon the fire. “In order to prevent any stoppage of the engine when it might be necessary to repair a boiler, two are now generally adopted, and the box B on the boiler top, which contains a stop valve, is prepared with an additional branch, to communi- cate with a second boiler. On the steam pipe, and leading to the cylinder, is placed a box containing a valve opening upwards, called a safety valve, and so weighted as to rise and let the steam escape when it is stronger than the engine requires. “The steam cylinder and its casing are cast together in one piece. A section of which, in plate 2, will explain the construc- tion of this important part of the engine, as well as the peculiar Construction of the valves for admitting the steam alternately to act on contrary-sides of the piston. The space betwixt the 101-2, cylinder and the casing being constantly filled with steam, prevents any condensation taking place within the cylinder, and serves also as a conducting pipe for the steam to the boxes E, containing the sliding valves, (which are generally called D valves, from their resemblance in form to that letter,) through two separate openings for that purpose, in each of which is placed a throttle valve, and on their spindles are levers communicating by a rod with the governor for the pur- pose of regulating the speed of the engine. “The valves F are packed on their circular sides with a soft substance of hemp or flax, and in consequence of the steam being admitted to the under side of the top valve, and the upper side of the bottom valve, they of course require no more force to move them than what is necessary to overcome the friction of the packing and the surface over which they slide. The weight of the valves and their rods are accurately counter- balanced by a moveable weight or a lever under the cylinder, and are moved by an eccentric circle, or the fly-wheel shaft, which is shewn on an enlarged scale in plate 2. By the arrangement of having two throttle valves, the least difference in weight between those parts of the engine that are attached to the opposite ends of the working beam, can be regulated, by allowing a little more steam to pass in the same time through either of the valves, as may be found necessary, thereby equa- lizing as much as possible the action of the engine. One pipe, G, only is required in front of the cylinder, and that for the purpose of conducting the steam from the apper side of the piston to the condenser H,-a vessel in which the condensa- tion of the steam is effected after its escape from the cylinder, by admitting a quantity of cold water out of the condensing cistern I, through an injection cock, the opening of which is regulated by hand. The condensing cistern is supplied with water by the cold-water pump K. “The air pump, (or, more properly, discharging pump,) for the purpose of removing the water from the condenser after its admixture with the steam, and keeping up a constant vacuum, with its valves and bucket, will be fully understood by a refer- ence to plate 2, as well as L, the hot-water pump, used for raising water to supply the boiler, which water passes through a small valve, and down the same pipe that contains the damper heat. This valve is connected with a lever, having one of its ends connected by a rod passing through a pipe with a stone float, that rises and falls with the surface of the water in the boiler, and thereby, admitting a smaller or larger quantity of water, as may be requisite. This pipe, for the rod to pass through, has several advantages over the method of passing it through a stuffing boa on the boiler top, as in case the hot water pump by any accident should cease to act, and the water get low in the boiler, the steam would make its escape before any serious injury could happen, shewing instantly that such was the fact the moment it got below the end of the pipe. The friction between the rod and the water being so triſling, insures an almost uniform regularity of action. “The little apparatus M, or self-acting water gauge, consists of a standard fixed on the boiler top, with a pulley, over which a chain passes connected at one end with a copper wire, and a stone float, which by its rising or falling indicates the exact variation that takes place in the height of the surface of the water, and is used in lieu of the gauge pipes and cocks formerly applied for that purpose, over which it has this great advantage, that besides shewing the water to be too high or too low, it shews exactly how much, by the pointer and scale that are affixed to it. “N, a small cistern containing the blow valve, for the pur- pose of allowing the air to escape from the cylinder, &c. pre- vious to the engine being set to work. “The crank P in o is made globular, to prevent any strain in case the shaft should get out of its level position by the unequal wearing of the brass steps under its tunnels, or any little sinking of the foundation.” -*— “In order to prevent the aceidents occasioned by the burst- ing of steam boilers, which are of such frequent occurrence, I must now solicit a little attention to the drawing and de- scription of a self-acting safety valve, of my invention, or rather the application of it to a new purpose; for a similar valve has been used as a clack for a pump upwards of a hundred; T. J. Mi * sºm-mºs * 962 S T E s T E DICTIONARY OF MECHANICAL scIENCE. years; and it will easily be perceived from the several advan- tages it possesses, that wherever its adoption shall take place it will be scarcely possible for any accident of this nature to arise. “The opening in the lower part of the box, which is fixed on the boiler top, or, if more convenient, on any part of a pipe having a free communication with it, requires to be of such a size as to allow a free discharge of all the steam the boiler is capable of generating. This opening is covered with a sphe- rical valve, the outer part of brass, which is filled with lead, of such dimensions, and consequently, of such weight, as to press with as many pounds per square inch, as it is intended the strength of the steam at a maximum in the boiler should ever be raised to. Now, as it is perfectly free from friction, the obvious effect will be, that at the very instant the steam arrives at this degree of pressure, the ball will be raised by its force, and a discharge will immediately take place. “The plate b, which is large enough to cover entirely the ball or valve, and thereby prevent its being pressed down, or at all interfered with, even by any bar or rod being forced down the discharging pipe, is connected with the cover by small bars c. The projections a are merely to prevent the ball at any time from being lifted off its seat. Originally the steam was discharged at the side-opening d, but this will be rendered unnecessary if the plan be adopted which has the discharging pipe in the lid or cover of the box, but both are drawn to shew the different methods of taking away the steam, and the selec- tion must be made according to convenience, and the judgment of the engineer: “From the nature of its construction, this safety valve, requiring no packing or attention, can be entirely secured from the officious meddling and carelessness of attendants; and a pipe may be attached to the opening in the box, and continued into the chimney, or any other convenient place of discharge. I should not recommend this valve to be used as a substitute for the Ördinary safety valve, (improperly so called,) but in all cases in addition, and so loaded as only to be brought into action at a very trifling additional pressure above that to which the other valve is weighted. This valve would be found of the greatest advantage, in preventing the boiling over of the feed pipes of boilers, when the rooms over them are used as drying stoves in print-works, bleach-works, &c. I ought to state, that I have had this description of valve in use upwards of four years, with the greatest regularity of action.” First Steam Boat.—Although it is only of late years that steam has been extensively applied to the propelling of vessels on water, yet, a knowledge of its capabilities for this purpose is of old date. As far back as the 21st of December 1736, Mr. Jonathan Hulls took out a patent for “A new-invented Machine for car- rying Vesssels or Ships out of, or into, any Harbour, Port, or River, against Wind and Tide, or in a Calm;” and in the foll- lowing year, he published a pamphlet in London, detailing at length the nature of his invention, which was nothing else than a tow-boat moved by steam, as represented in the annexed engraving. The description of the mode of working it we shall give in his own words - In some convenient part of the tow-boat, there is placed a vessel, about two-thirds full of water, with the top close shut. This vessel being kept boiling, rarefies the water into a steam. This steam being conveyed through a large pipe into a cylin- drical vessel, and there condensed, makes a vacuum, which causes the atmosphere to press on this vessel, and so presses down a piston that is fitted into the cylindrical vessel, in the same manner as Mr. Newcomen's engine with which he raises the water by fire. “Fig. 1, P, is the pipe coming from the furnace to the cylin- der. Q, is the cylinder wherein the steam is condensed. R, the valve that stops the steam from coming into the cylinder whilst the steam within the same is condensed. S, the pipe to convey the condensing water into the cylinder. T, a cock to let in the condensing water when the cylinder is full of steam, and the valve P is shut. U, a rope fixed to the piston that slides up and $own the cylinder. “Note:–This rope U is the same rope that goes round the wheel D in the machine fig. 2. - “Fig. A the chimney coming from the furnace. B the tow- toat. C C two pieces of timber, framed together to carry the machine. D a D and D b are three wheels on one axis, to receive the ropes Mf l and Fa. Ha and H b are two wheels on the same axis with the fans I I I I I I, and move alternately in such a manner, that, when the wheels D a D and D b move backward or forward, they keep the fans in a direct motion. Ff is a rope going from Hºb to D b, that when the wheels D a D and D b move forward, moves the wheel H b forwards, which brings the fans forward with it. Fa is a rope going from the wheel H a to the wheel D a, that, when the wheels Da and D b move forward, the wheel H a draws the rope F, and raises the weight G, at the same time as the wheel Hb brings the fans for- ward. When the weight G is so raised, while the wheels D a D and D b are moving backward, the rope F a gives way, and the power of the weight G, brings the wheel H a forward and the fans with it, so that the fans always keep going forward, not- withstanding the wheels D a D and D b move backwards and forwards as the piston moves up and down in the cylinder. L. L. are teeth for a catch to drop in from the axis, and are so con- trived, that they catch in an alternate manner to cause the fang to move always forward for the wheel H a, by the power of the weight G, is performing its office, while the other wheel H b goes back in order to fetch another stroke.” - s: *ms # *s-s = The next attempt was that of Mr. Symington. In his boat, by placing the cylinder nearly in a horizontal position, the introduc- tion of a beam is avoided. The piston is supported in its position by friction wheels, and communigates by means of a joint with a crank, connected with a wheek; which gives the water-wheel, by means of its teeth, a motion somewhat slower than its own ; the water-wheel serving also as a fly. This water-wheel is situated in a cavity near the stern, and in the middle of the breadth of the boat, so that it becomes necessary to have two rudders, one on each side, connected together by rods, which are moved by a winch near the head of the boat, so that the per- son who attends the engine may also steer. Mr. Symington likewise placed an arrangement of stampers at the head of the boat, for the purpose of breaking the ice on canals, an opera- tion often attended with great labour and expense. These stampers were raised in succession by levers, the ends of which were depressed by the pins of wheels turned by an axis com- municating with the water-wheel. A drawing of this steam- | boat is given in vol. i. of Dr. Young’s Natural Philosophy. The first steam-boat in America was launched at New York on the 3d of October 1807, and began to ply on the river between that city and Albany, a distance of about 120 miles. In the common wheel paddles at present employed for pro- pelling steam-boats, “there are, it appears to me, (says Mr. Clark,) two defects, which are yet left to the ingenuity of the mechanic to remove. In the first place, they are defective, on account of the declivity with which they enter and come out of the water. In the second place, the successive paddles are commonly placed so very near one another, that when one paddle enters the water, it leaves, by its swift motion, 3. current, into which the next paddle enters; which, instead S T E S T E DICTIONARY OF MECHANICAL SCIENCE. 963 of moving in an opposite direction to the paddles, moves in the same. Great resistance is thus lost. To remedy the former of these defects, several attempts have been made in this country. These attempts, however, have commonly been unsuccessful, on account of the great contingency of force which steam-boat paddles are called to bear. The latter of the defects which I have stated, has not, however, so far as I am aware, met the attention of the mechanics of this country. “About two years ago, I made some attempts at the removal of these defects. The following is an account of one of the plans which occurred to me. - Q º “Fig.2 is a plan of the machine; fig. 3 is a sectional view. The same letters refer to both. A A fig. 2, is the side of the boat. B B, BB, figs. 2 and 3, is the frame to support the machinery. Iſø/2. £’ g tº € A- Iſutºlitigantingtºniºtiſ #. A. |||ſ|{{#||||||||||ſ;| ſº- | º #|B B d [. la É #Tº jºf | dºm F drº-H ja c/Fé | i ||||IIIHEIT=l - --- º º Q {\|= Jº \ºſſºſ.TTTTTT a is the shaft which turns the wheel b, whose teeth run into those of the wheels & c, and turn both in the same direction. These wheels are connected, by a shaft, with the double cranks d d d, d dd. These cranks are inclined to one another, at equal angles, and are of equal lengths. e e e are bars, connecting these cranks in such a manner as to preserve the corresponding cranks on the different shafts, parallel to one another, as shewn in fig. 3, fff are paddles affixed perpendicularly to these bars. These paddles alone, or the paddles and the bars together, may be so fixed as to be removable at pleasure.” SNIIII Á ſ ſ º # TTTTTTTTTTTTTTTTTTTºmºrºlliſDºminºly B * º º iñº N - Rºx * - * - - - * * * From this description, it is evident that the cranks on the same shaft will always preserve the same inclination to one another ; that the corresponding ones on different shafts will always be parallei ; that the bars connecting them will always be horizontal ; and consequently that the paddles must always enter, pass through, and rise out of the water, perpendicularly to its surface. The terminations of the paddles move in a circle, as represented in fig. 3 by a dotted line. The radius of this circle is equal to the length of any of the several cranks. It is evident, also, that every successive paddle enters in a current different from that caused by the one which it follows. Of an excellent plan for the consuming of smoke, invented by Mr. Chapman, of Whitby, and for which he was rewarded with the large silver medal by the Society of Arts, the following is his account :— “It is well known to all that are conversant on the subject, that it is necessary to admit a proportion of pure atmospheric air, to unite with the smoke after it is generated in the furnace, in order to supply the oxygen gas, without which it will not inflame. It is likewise known that any air admitted into the body of the furnace, if it does not go through the burning fuel, has a great tendency te cool the bottom of the boiler, and retard the generation of steam. To obviate this, it is the general of iron which hangs by a rivet above. practice, in the construction of those furnaces which consume the smoke, to admit the air partly at the ash-pit, and partly up through the fire-bridge. I offer, for the consideration of the Society, an improved plan, which I have adopted, and which has answered beyond my utmost expectations. It is as follows:— “To heat the air before its admission into the furnace. This I do by casting the grate bars hollow from end to end, so that they form a series of parallel tubes, which open in two boxes, one placed in front, and the other behind the grate." In the front box, directly under the fire-door, I make a register to open and shut, to any extent, at pleasure. The other end I connect with the brickwork directly underneath the fire-bridge, which fire-bridge I make double, with a small interval between, say one inch ; the interval to go across the furnace from side to side, and rather to incline forward, or towards the fire-door, so as to meet and reverberate the smoke on to the ignited fuel in the grate, which causes it to inflame and become a sheet of bright fire under the bottom of the boiler. From what I have said it will appear, that if the front register is open, or partially so, there will be a great draught of air through it, along the interior of the grate bars, thence into the flue of the fire-bridge, and out of the orifice at top, which air will be heated in its passage through the bars, before it comes in contact with the smoke, when it will give out its oxygen, and cause it to inflame. “Such was my view of this part of the subject in theory, and I have found it to succeed in practice, in a small engine of my own. But a further improvement was necessary to make it quite perfect. There are few people who are aware of the ex- tent of the mischief arising from the old method of charging a grate by the front door. Now, in my engine, (which has only two-horse power), I calculated that every time the fire-door was opened, to stir the fire and replenish the fuel, there could not be less than from forty-five to fifty feet of cold atmospherical air admitted into the furnace, which so cooled the heated gases, &c. that, however complete the plan was in other respects, the smoke could not possibly inflame, from being so cooled, till a considerable time after the fire-door was shut. “To obviate this, I have adopted a cast iron hopper above the fire-door, with a type at the bottom, that has two pivots at one side and open at the other; one pivot goes through the end of the hopper, and has a counter-lever to keep the type shut when a sufficient quantity of coal for a charge is on it. The top of the hopper is covered with a lid, which I shut down during the time of firing, then, by lifting the lever which opens the type inside, the coals slide down on to the fore end of the grâte bars, which is only the work of a moment. . It is evident that no quantity of cold air can thus get into the furnace; in fact, it is not possible for any person that does not see the operation of firing to know when fresh fuel is added by looking at the top of the chimney. The smoke that issues is never more than a light gray, just perceptible, but in a general way is not seen at all. “The coals last admitted, after lying a short time at the front of the more ignited fuel, become partially coked, and just before I admit a fresh supply, I push the last charge further along the grate, by a tool made for the purpose, which remains constantly in the furnace. It consists of a plate of iron about four inches broad; its length goes across the grate with a round bar of iron riveted into its centre, at right angles, to form a handle, which comes through a hole made at the bottom of the fire-door, and is long enough for a man to use with both hands, so that he ean either push from, or pull towards him, to manage the fire within, without opening the fire door, except when the grate wants cleaning, &c. &c. For better knowing when the fire wants stirring or replenishing, I have a hole, about an inch in diameter, in the fire door, to look through, covered by a piece After I have used the above instrument, I pull it up close to the fire-door, where it remains till it is again wanted; and the coals, when let into the fire, fall down beyond it. º “The above-written account constitutes the whole of my improvements, as far as is required by the Society, but not the whole of the advantages gained by my invention. For instance, the durability of the grate bars by the admission of air through them. I may add, that I examined my own yesterday, and I do not find them any worse, although they have been in use fº four months.” - 964 S T E S T E 10 ICTIONARY OF MECHANICAL SCIENCE. STEAM PRINTING. See PRINTING BY Steam. STEATITES, in Mineralogy, is usually amorphous, but some- times crystallized in six-sided prisms. Its texture is com- monly earthy; specific gravity 2.61 to 2.79; feels greasy; sel- dom adheres to the tongue; colour white or gray, with a tint of other colours; the foliated green. STEEL, a most valuable metal, consisting of iron combined with carbon. It is chiefly used for edge-tools, and other sharp and cutting instruments where hardness is required; and from the fine polish of which it is susceptible, it is used in ornaments of various kinds. . By heating steel to redness, and cooling it suddenly, it can be made much harder than any other metal; and if heated to a lower temperature than redness, and sud- denly cooled, it becomes the most elastic of all the metals. STEELING, in Cutlery, the laying on a piece of steel upon a larger mass of iron, that the part which is to receive the edge, may be harder than the rest. - STEELYARD, a kind of balance, called also the Roman talance, by means of which the gravities of different bodies are : found by a single weight being placed on the lever or beam, so as to secure an equilibrium; the notches and figures marked on it, denoting the number of pounds. Steely ARD Spring, a kind of portable balance, serving to weigh any article not exceeding forty pounds. . It is composed of a brass tube, in which is a rod, round which is wound a spring of tempered steel, in a spiral form. On this rod are marked pounds, and the divisions of pounds, and to the part of the rod at the bottom of the tube, is a hook, on which the article to be weighed, is fastened. Now, the other part of the rod being made fast to the spiral spring, it must be obvious that the greater the weight which is attached to the hook, the more will the spring be pressed and contracted; and conse- quently the greater will be the part of the rod drawn out of the tube, on which are marked the number of pounds that have thus drawn it out. - STEEPLE, an appendage to a church, generally raised at the western end, for ornament, and also to hold the bells. Both towers and spires come under the denomination of steeple. STEERAGE, an apartment before the great cabin, from which it is separated by a partition or bulk-head. In merchant- ships it is generally the habitation of the inferior officers and crew ; but in ships of war it serves only as a hall or anti- Steerage, is also used to express the effort of the helm. Steerage-Way, implies a chamber to the great or captain’s cabin. sufficient degree of motion communicated to a ship for her to become susceptible of the effects of the helm in governing her COUM TS6, * STEERING, may be defined the art of directing a ship's way by the movements of the helm, or of applying its efforts to re- ‘gulate her course when she advances. The perfection of steering, consists in a vigilant attention to the motion of the ship’s head, so as to check every deviation from the line of her course in the first instant of its motion, and in applying as little of the power of the helm as possible. By this she will run more uniformly in a straight path, as declining less to the right and left; whereas, if a greater effort of the helm is employed, it will produce a greater declination from the course, and not only increase the difficulty of steering, but also make a crooked and irregular track through the water. The phrases used in steer- ing a ship vary according to the relation of the wind to her course. Thus, if the wind is fair or large, the phrases used by the pilot or officer who superintends the steerage, are Port, Starboard, and Steady. The first is intended to direct the ship's course further to the right, the second is to guide her further to the left, and the last is designed to keep her exactly in the line on which she advances, according to her prescribed course. . The excess of the first and second movement is called Hard-a-Port, and Hard-a-Starboard; the former of which gives the greatest possible inclination to the right, and the latter an equal tendency to the left. If, on the contrary, the wind is foul and scant, the phrases then used are Luff, Thus, and No-Near. The first of which is the order to keep her close to the wind; the second, to retain her in her present situation ; and the third, to keep her sails full. In ships of war, the duties of con- ning and steering are divided amongst the quarter-masters, their mates, and the most expert seamen, who attend the helms in turns. The steerage is constantly supervised by the quar- ter-masters. In merchant-ships, every seaman takes his turn in steering, being directed therein by the mate of the watch, or some other officer. As the safety of a ship, and all contained therein, depend in a great measure on the steerage and effects of the helm, the apparatus by which it is managed should often be examined by the proper officers. Indeed, when the fatal effects which may result from negligence in this important duty are duly considered, such inattention must be pronounced un- pardonable. - - - - STEERSMAN, the helmsman, or timoneer; which latter appellation is derived from the French term, which signifies an helmsman. He is reckoned the best steersman who uses the least motion in putting the helm over to and again, and who keeps the ship best from making yaws, that is, from running in and out. For this purpose, he should diligently watch the movements of the head by the land, clouds, moon, or stars; because, although the course is in general regulated by com- pass, the vibrations of the needle are not so quickly perceived, as the sallies of the ship's head to the right or left, which, if not immediately restrained, will require additional velocity in every instant of their motion, and demand a more powerful impulse of the helm to reduce them; the application of which will operate to turn her head as far on the contrary side of her COUITS6. STEEVING, the angle of elevation which a ship's bowsprit makes with the horizon. STEM, a circular piece of timber, into which the two sides of a ship are united at the fore end; the lower end of it is scarfed to the keel, and the bowsprit rests upon its upper end; the ends of the wales and planks of the sides and bottom are let into a groove or channel cut in the middle of its surface, from top to bottom. The outside of the stem is usually marked with a scale of feet, answering to a perpendicular from the keel. Its use is to ascertain the draught of water at its fore part, when the ship is in preparation for a sea voyage, &c. The stem at its lower end is of equal breadth and thickness with the keel, but it grows proportionally broader and thicker towards its upper extremity. False Stem, is that fixed before the right one. When a ship’s stem is too flat, so that she cabnot keep a wind well, they put a false stem above, which makes her rid more way, and bear a better sail. To Stem a Tide, to acquire a velocity in sailing against the tide equal to the force of the current. From Stem to Stern, from one end of the ship to the other. STEM. See STALK. * STEMMATA, in the history of insects, are three smooth he- mispheric dots, placed generally on the top of the head, as in most of the hymenoptera and other classes. STEMSON, an arching piece of timber fixed within the apron, to reinforce the scarf thereof, in the same manner as the apron supports the scarf of the stem. STENOGRAPHY. The art of short-hand writing. The fol- lowing scheme is that which has received most general appro- bation from its simplicity, and being founded on rational prin- ciples, by which it is easily acquired and retained. Rules for Orthography in Short Hand.—All quiescent conso- nants in words are to be dropped ; and the orthography to be directed only by the pronunciation ; which being known to all, will render this art attainable by those who cannot spell with precision in long hand. 2. When the absence of consonants not entirely dormant can be easily known, they may often be omitted without the least obscurity. 3. Two, or sometimes more consonants, may, to promote greater expedition, be ex- changed for a single one of nearly similar sound, and no ambi- guity as to the meaning ensue. 4. When two consonants of the same kind or same sound come together, without any vowel between them, only one is to be expressed ; but if a vowel or vowels intervene, both are to be written; only observe, if they are perpendicular, horizontal, or oblique lines, they must only be drawn a size longer than usual ; and characters with slopes must have the sides of their heads doubled. See PLATE. Might is to be written mit, fight, fit, machine, mashin, enough, enuf, laugh, laf, prophet, profet, physics, fisiks, foreign, foren, sovereign, sovren, psalm, sam, receipt, reset, write rite, island, iland. In short, all that the short-hand writer has to do with S T E S T E DrctionARY of MECHANICAL scIENCE. 1965 orthography, is to produce the clear and distinct sound of his word in the shortest and most compact manner possible. 1. Vowels, being only simple articulate sounds, though they are the connectives of consonants, and employed in every word and every syllable, are not necessary to be inserted in the mid- ‘dle of words; because the consonants if fully pronounced, with the assistance of connexion, will always discover the mean- ing of a word, and make the writing perfectly legible. , 2. If a vowel is not strongly accented in the incipient syllable of a word, or if it is mute in the final, it is likewise to be omitted; because the sound of the incipient vowel is often implied in that of the first consonant, which will consequently supply its place. 3. But if the vowel constitutes the first or last syllable of a word, or is strongly accented at its begin- ning or end, that vowel is continually to be written. 4. If a word begin or end with two or more vowels, though separated, or when there is a coalition of vowels, as in diphthongs and triphthongs, only one of them is to be expressed, which must be that which agrees best with the pronunciation. 5. In mono- syllables, if they begin or end with a vowel, it is always to be inserted, unless the vowel e is mute at the end of a word. The short-hand alphabet consists of 18 distinct characters, taken from lines and semicircular curves; the formation and application of which we shall now explain, beginning with the vowels. For the three first vowels a, e, and i, a comma is appro- priated in different positions; and for the other three o, u, and 3y, a point. The comma and point, when applied to a and o, is to be placed as in the plate, at the top of the next character; when for e and u opposite to the middle; and when for i and y at the bottom. Simple lines may be drawn four different ways perpendicular, horizontal, and with an angle of about 45 de- grees to the right and left. An ascending oblique line to the right, which will be perfectly distinct from the rest when joined to any other character, may likewise be admitted. These cha- racters being the simplest in nature, are assigned to those five consonants which most frequently occur, viz, l, r, t, c hard, or k, and c soft, or s. Every circle may be divided with a perpendi- cular and horizontal line, so as to form likewise four distinct characters. These being the next to lines in the simplicity of their formation, we have appropriated them for b, d, n, and m. The characters expressing nine of the consonants are all per- fectly distinct from one another; eight only remain which are needful, viz., f: g, or j, h, p, q, w, w, and ac, to find characters for which we must have recourse to mixed curves and lines. The characters which we have adopted are the simplest in nature after those already applied, admit of the easiest joining, and tend to preserve lineality and beauty in the writ- ing. It must be observed, that we have no character for c when it has a hard sound as in castle, or soft as in city; for it natu- rally takes the sound of k or s, which in all cases will be suffi- cient to supply its place. R likewise is represented by the same character as l; only with this difference, r is written with such an ascending stroke, and l with a descending: which is always to be known from the manner of its union with the follow- ing character; but in a few monosyllables where r is the only consonant in the word, and consequently stands alone, it is to be made as is shewn in the alphabet, for distinction's sake. Z, as it is a letter seldom employed in the English language, and only a coarser and harder expression of s, must : be supplied by s when ever it occurs; as for Zedekiah, write Sedekiah, &c. 4. The terminative character for tion, sion, cion cian, tian, is to be expressed by a small circle joined to the nearest letter and turned to the right. , 5. The terminative character for ing is to be expressed likewise by a small circle but drawn to the left hand, and its plural ings by a dot. 6. The plural sign s is to be added to the terminative characters when necessary. 7. The separated terminations are never to be used but in poly- syllables, or in words of more syllables than one. The following is the explanation of the different arbitraries and abreviations in the plate:—No. 1, As—2, Nation—3, Thing–4, Circumstance—5, Counterfeit—6, Visible–7, Himself—8, Them- selyes—9, Atonement—10, Therefore—11, Christ—12, Multi- | him from the captain's or the ward-room stewards, who are tude—13, Descendants—14, Government—15, Everlasting. The most usual abbreviation, is to use the full letter of a word } tains and lieutenants, &c. with a dot under it, to shew it is an abbrevation. , 101-2 length. of a person laughing.—The noody, is a foot and a quarter long, and is frequently met with at sea, between the tropics.—The great tern, is found in various parts of Europe, and in summer STEP, a block of wood fixed on the decks or bottom of a ship, and having a hole in its upper side fitted to receive the heel of a mast or capstan. secure it in readiness for setting sail. To Step a Boat's Mast, is to erect and STEREOGRAPHY, the art of drawing the forms and figures of the solids upon a plane. - STEREOMETRY, that part of geometry which teaches how to measure solid bodies, that is, to find the solidity or solid con- tents of bodies, as globes, cylinders, cubes, vessels, ships, &c. STEREOTYPE PRINTING. The mode of stereotype print- ing is first to set up a page, for instance, in the common way, and when it is rendered perfectly correct, a cast is taken from it, and in this cast the metal for the plate is poured: the plates thus procured are afterwards worked on blocks in the common way. STERILITY, the state of that which is barren, whether ani- mal or vegetable, in opposition to fecundity or fruitfulness. STERLING. A pound, shilling, or penny, sterling, signifies as much as a pound, shilling, or penny, of lawful money of Great Britain as settled by authority. - STERN, the posterior part of a ship, or that part which is presented to the view of a spectator, placed on the continuation of the keel, behind. The stern is terminated by the taffarel above, and by the counters below. It is limited on the sides by the quarter-pieces, and the intermediate space comprehends the galleries and windows of the different cabins. STERN-Fast, a rope used to confine the stern of a ship, lighter, or boat, to any wharf or jetty-head, &c. STERN-Frame, the several pieces of timber which form the Stern. • * - STERNMOST, implies any ship or ships that are in the rear or farthest astern, as opposed to headmost. STERN-Post, a long straight piece of timber, erected on the extremity of the keel, to sustain the rudder, and terminate the ship behind. It is usually marked like the stem with a scale of feet, from the keel upwards, in order to ascertain the draught of water abaft. This piece ought to be well served and supported, because the ends of all the lower planks of the ship's bottom are fixed in a channel cut on its surface, and the whole weight of the rudder is sustained by it. The diffi- culty of procuring a stern-post of sufficient breadth in one piece, has introduced the practice of fixing an additional piece behind it, which is strongly bolted to the former; the hingcs which support the rudder are accordingly fixed to this latter, which is also tenoned into the keel, and is denominated the back of the post. The stern-post is strongly attached to the keel by a knee, of which one branch extends along the keel, being scarfed to the dead-wood, and fore-locked under the keel, whilst the other branch inclines upwards, and corresponds with the inside or forc part of the stern-post, to which it is also bolted in the same manner. STERN-Sheets, that part of a boat which is contained be- tween the stern and the aftmost seat of the towers. It is generally furnished with seats to accommodate passengers. Stern-Way, the movement by which a ship retreats or goes backward with her stern foremost. STERNA, the Tern, in Natural History, a genus of birds of the order anseres. There are twenty-five species. The follow- ing are the principal : S. caspia, or the Caspian tern. This abounds on the seas wherein it derives its name. It fishes also in rivers, and sometimes suddenly darts upon its prey from a considerable height, and at other times skims the surface of the water in the manner of a swallow. It is nearly two feet in It lays only two eggs, and its sound resembles those on the British coasts. It is fourteen inches long. Its manners on the water resemble those of the swallow by land. STEWARD, in Naval affairs, is an officer in a ship of war, appointed by the purser to distribute the different species of provisions to the officers and crew, for which purpose he is furnished with several assistants. He is generally denomi- nated the purser's steward, or the ship's steward, to distinguish appointed to take care of the sea-stock belonging to the cap- T 1 N 966 S T O S T O DICTIONARY OF MECHANICAL SCIENCE. Stew ARD, a man appointed in a place or stead, and always signifies a principal officer within his jurisdiction. STICK, Gold. An officer of superior rank in the life-guards, so called, who is in immediate attendance upon the king's per- son. When his majesty gives either of bis regiments of life- guards to an officer, he presents him with a gold stick. The colonels of the two regiments wait alternately month and month. The one on duty is then called gold stick in waiting, and all orders relating to the life-guards are transmitted through him. During that month he commands the brigade, receives all reports, and communicates them to the king. . This tempo- rary command of the brigade does not, however, interfere with the promotion that may be going forward, as each colonel lays those of his own particular corps before his majesty. Former- ly the gold stick commanded all guards about his majesty's person. On levees and drawing room days, he goes into the king's closet for the parol. - a Stick, Silver. The field-officer of the life-guards when on duty is so called. The silver stick is in waiting for a week, during which period all reports are made through him to the gold stick; and orders from the gold stick pass through him to the brigade. In the absence of the gold stick, on levees and drawing-room days, he goes into the king's closet for the parol. STIFF, the quality by which a ship is enabled to carry a sufficient quantity of sail without oversetting. STIGMA, in Entomology, a spot or anastomosis in the mid- dle of the wings of insects, near the anterior margin, sonspi- cuous in the hymenopterous tribes. STIGMATA, in Natural History, the apertures in diſferent parts of the bodies of insects, communicating with the trachae or air-vessels, and serving for the office of respiration. STILL, the name of an apparatus used in distillation. . See DISTILLATION. . STIMULANT, in Medicine, any agent which has the property of increasing the mobility, or of exciting the motions of the living body, or its moving parts. STING, an apparatus in the body of certain insects, in form of a little spear, serving them as a weapon of offence. STINK-Pot, an earthen jar, charged with powder, grenades, and other materials of an offensive and suffocating smell. It is sometimes used by privateers, to annoy an enemy whom they design to board. See the article BoARD ING. STIPPLING, a mode of engraving on copper by means of dots, as contradistinguished from a course of Gontinued lines. STITCH, in Agriculture, a ridge or butt in a field which is under the plough. The dimensions of a stitch are liable to many variations in different districts. d STOAT, in Zöology, the name of an animal whose skin is the ermine. These creatures are plentiful in Russia and Norway, where an extensive trade in their skins is carried on. Their fur changes colour with the seasons of the year. When the snow is on the ground, its celebrated whiteness appears to the greatest advantage. * - STOCK, generally implies provisions procured by indi- viduals, for the particular accommodation of themselves or messmates; hence we say, fresh stock, sea stock, live stock. STOCKINGS, the clothing of the leg and foot. Anciently stockings were made of cloth or milled stuff sewed together, but since the knitting and weaving of stockings have been invented, cloth has been entirely laid aside. Henry II. of France, in 1559, was the first who wore silk stockings. Henry VIII. and Queen Elizabeth, were the first who wore silk stockings in England, and these were brought from Spain, where the invention seems to have had its birth. In the third year of Elizabeth, the art of knitting was introduced into Eng- land, and to this honour the Scotch lay claim. The stocking loom is generally thought to have been invented by William Lee, M. A. of St. John’s College, Cambridge, a native of Wood- borough, near Nottingham, in the year . 1589; but receiving little encouragement, and being in indigent circumstances, he went to France, where, meeting with further disappointment, he died of a broken heart. *. STOCKS, a frame erected on the shore of a river, whereon to build shipping. It generally oonsists of a number of wooden blocks ranged parallel to each other at convenient distances, and with a gradual declivity towards the water. . STOCKs, the public funds of the nation, instituted for the purpose of paying the interest upon loans. Stocks, a wooden machine to put the legs of offenders in, for the securing of disorderly persons, and by way of punish. ment in divers cases ordained by statute, &c. . STOLE, GRoom of THE, the eldest gentleman of his majesty's bed-chamber, whose office and honour it is to present and put on his majesty’s first garment, or shirt, every morning, and to order the things into the chamber. - STONEHENGE, a stupendous monument, of Druidical antiquity, standing on Salisbury plain, and supposed to be nearly coeval with the pyramids of Egypt. are buried in impenetrable obscurity. STONES and EARTHs. The only substances which enter into the composition of the simple stones, as far at least as analysis has discovered, are the six earths, silica, alumina, Its origin and use zirconia, glucina, lime, and magnesia; and the oxides of iron, manganese, nickel, chromium, and copper, Seldom more than four or five of these substances are found combined together in the same stone. - - - : STON E-Ware. Under the denomination stone-ware are com- prehended all the different artificial combinations of earthy bodies which are applied to useful purposes. . -- STOP, in Music, a word applied by violin and violincello performers, to that pressure of the strings by which they are brought into contact with the finger-board, and by which the pitch of the note is determined. * . STOP, Trumpet, a reed metallic stop, so called because its tone is imitative of the trumpet. . STOPPER, of the Anchor, a strong rope attached to the cat-head, which, passing through the anchor-ring, is afterwards fastened to a timber-head, thereby securing the anchor on the bow. Stoppers, of the cables, commonly called deck-stoppers, have a large knot and a laniard at one end, and are fastened to a ring-bolt in the deck by the other; they are attached to the cable by the laniard, which is fastened securely round both by several turns passed behind the knot, or about the neck of the stopper, by which means the cable is restrained from running out of the ship when she rides at anchor. Dog-Stoppers, is a strong rope clenched round the main-mast, and used on parti- cular occasions to relieve and assist the preceding when the ship rides in a heavy sea, or otherwise bears a great strain on the cable. Wing-Stoppers, similar pieces of rope clenched round one of the beams near the ship's side, and serving the same purpose as the preceding. Stoppers of the rigging, have a knot and a laniard at each end; they are used when the shrouds, stays, or back-stays, are cut asunder in battle, or disabled in tempestuous weather, and are then lashed, in the same manner as those of the cables, to the separated parts of the shroud, &c. which are thereby reunited so as to be fit for immediate service. This, however, is only a temporary expedient, applied when there is not time or opportunity to refit them by a more complete operation. Stoppers, are also pieces of rope used to prevent the running rigging from coming up whilst being belayed. - Stoppers, certain short pieces of rope, which are usually knotted at one or both ends, according to the purnose for which they are intended. STORAX, in the Materia Medica, is the resinous drug which issues in a fluid state from incisions made in the bark or branches of the storax tree. It can be obtained in perfection only from those trees which grow in Asiatic Turkey. STORE-Keeper, an officer invested with the charge of the principal stores. Store-Room, an apartment or place of reserve, of which there are several in a ship, to contain the provisions or stores of a ship, together with those of her officers. STORES, if any person who has the charge or custody of any of the king's armour, ordnance, ammunition, shot, powder, or habiliments of war, or sf any victuals for victualling the nayy, shall, to hinder his majesty's service, embezzle, purloin, or convey away the same to the value of 20s. or shall steal or em- | bezzle any of his majesty’s sails, cordage, or any other of his naval stores, to the value of 20s. he shall be adjudged guilty of felony, without benefit of clergy. 22 Car. II. c. 6. . . - STORK, a large bird of the heron class, of which many particulars are related that are remarkably singular. It is a S T R S T R. 967 DICTIONARY OF MECHANICAL SCIENCE. bird of passage. Egypt is said to be the place of its winter residence. It is in high repute among the Mahometans, ap- proaching almost to veneration. tº & . STORM, a term signifying a fall of snow, hail, or rain; also high wind, thunder, &c. In some places the term is restricted to high winds, thunder, &c. ſº STOVE, in Building, is a hot-house or room, but in a more restricted sense it is a place in which fires in dwelling-houses are made, and so contrived that it may communicate heat to the room, and send the smoke up the chimney. Stoves are of various constructions, and numerous patents have been taken out for inventions and improvements in what had been pre- viously known. The great excellence of a stove consists in its adaptation to give the heat to the room, and to exclude the smoke. Towards these desirable objects many advances, have been made, both by Englishmen and foreigners; but much yet remains to be done. See FIRE-PLACE. tº g & STOVES, square boxes made of plank, and lined with brick, for burning charcoal in, to dress the admiral's victuals. STOWAGE, the general disposition of the several materials contained in a ship’s hold, with regard to their figure, magni- tude, or solidity. In the stowage of different articles, as ballast, casks, cases, bales, or boxes, there are several general rules to be observed, according to the circumstances or qualities of those materials. The casks which contain any liquid are, according to the sea phrase, to be bung up and bilge free, that is, closely wedged up in an horizontal position, and resting on their quarters, so that their bilges (or where they measure most round) being entirely free, cannot rub against each other, or the ship's side, by the motion of the vessel. , Dry goods, or such as may be damaged by the water, are to be carefully en- closed in casks, bales, cases, or wrappers, and wedged off from the bottom or sides of the ship, as well as from the bows, masts, and pump-well, &c. Due attention must likewise be had to their disposition, with regard to each other, and to the trim and centre of gravity of the ship, so that the heaviest may always be nearest the keel, and the lightest gradually above them. STRAIT, a narrow channel or arm of the sea, contained between two opposite shores; as, the straits of Gibraltar, the straits of Sunda, the straits of Dover, &c. - STRAKES, or StreAks, the uniform ranges of planks on the bottom or sides of a ship, or the continuation of planks joined to the end of each other, and reaching from the stern, which limits the vessel forward, to the stern-post and fashion-pieces, which terminate her length abaft. Garboard-Streak, is the lowest streak or range of planks, being let into rabbets in the keel below, and in the stem and stern-post at the ends. See the article Kee L. STRAMONIUM, in Botany, Datura, Common Thornapple, is a powerful narcotic poison, and in many instances its deleterious effects have been attended with pernicious, and even fatal con- sequences. Some have fancied that smoking stramonium has proved beneficial in asthmatic complaints, and for shortness of breath. STRAND, one of the twists or divisions of which a rope is composed. Strand also implies the sea-beach. Stranded, speaking of a cable or rope, signifies that one of its strands is broken. aground on the sea-shore, either by a tempest, or through bad steerage. Where any vessel is stranded, the justices of the peace are empowered to command the constables near the coast to call assistance, in order to preserve the ship, if possible. STRAPADO, a barbarous military punishment, now aban- doned. It consisted in having the hands of the offender tied behind his back, by which he was drawn to a certain elevation by a rope, then left to run suddenly towards the ground, when being stopped with a sudden jerk, his shoulders were dislo- cated. This was also one of the punishments of the inquisition, and perhaps it has been re-established with the restoration of that infernal tribunal. STRATA, in Natural History, the several beds or layers of different matters, whereof the body of the earth is composed. STRATAGEM, in War, a military wile or ‘device for de- ceiving or deluding an enemy. The ancients were more expert in stratagems than the moderns, except the Indians of America, who in this art of circumvention are exceedingly dexterous. Stranded, applied to a vessel, means that she has run STRAW, in Agriculture, the common name of the stem on which grain grew, and from which it is thrashed. A consider- able portion is used as fodder, for various other purposes, and finally as manure. $ STREAKY Cheese, in rural economy, is made from a mix- ture of new and old curd, or of two sorts which have different proportions of colouring in them, giving a variegated appear- ance, and hence the name. STREAM TIN, in Minerology, consists of particles or masses of tin ore, found beneath the surface in alluvial grounds, gene- rally in low situations. Its name is derived from the streams of water used to separate the earthy matter from it. This ore is of the best quality, and is occasionally mixed with small particles of gold. Stream Works, are the usual repositories in which the stream tin is found. Streaming, denotes the manage- ment of a stream work, or of stream tin during the process of refinement. - - STRENGTH. All experiments made on the strength of materials, when well conducted, are highly valuable, in as much as they lie at the very foundation of mechanical science, as applied to practice. Those acquainted with the history of mechanics, cannot be ignorant that many machines, otherwise well contrived, have been found quite inadequate to their pro- posed ends; some of them not having strength enough, in dif- ferent parts, to bear the pressure of the rest; and others, on the contrary, so loaded with unnecessary matter as to be ready to fall to pieces by their own weight. The same remark is applicable to architectural structures, many of which have given way only from a want of due proportion in the strength and weight of the different parts. And we add, that the value of such experiments is greatly increased, by having the manner in which they were conducted, (as in the present instance,) laid before the public ; as any error in applying the means em- ployed, or in deducing the inferences, is thus avoided; or, if any have been committed, may be detected. We purpose, therefore, in the first place in this article, to lay before our readers some experiments made by George Rennie, Esq. civil engineer, and which were first published in the Philosophical Transactions for 1818. The notes with which the article is accompanied, add not a little to its value, being by Mr. Thomas Tredgold, to whom the public is indebted for several valuable practical works, possessing considerable merit, and highly useful to mechanics and builders. The notes were first given to the world in the late Dr. Tilloch's Magazine for 1819. Preliminary Remarks.-The knowledge of the properties of bodies which come more immediately under our observation, is so instrumental to the progress of science, that any approxima- tion to it deserves our serious attention. The passage over a deep and rapid river, the construction of a great and noble edifice, or the combination of a more complicated piece of mechanism, are arts so peculiarly subservient to the applica- tion of these principles, that we cannot be said to proceed with safety and certainty, until we have assigned their just limits. The vague results on which the more refined calculations of many of the most eminent writers are founded, have given rise to such a multiplicity of contradictory conclusions, that it is difficult to choose, or distinguish the real from that which is merely specious. The connexions are frequently so distant, that little reliance can be placed on them. The Royal Society appears to have instituted, at an early period, some experi- ments on this subject, but they have recorded little to aid us. Emerson, in his Mechanics, has laid down a number of rules and approximations. Professor Robinson, in his excellent treatise in the Encyclopaedia Britannica; Banks on the Power of Machines; Dr. Anderson, of Glasgow; Colonel Beaufoy, &c. are those, amongst our countrymen, who have given the result of their experiments on wood and iron. The subject, however, appears to have excited considerable attention on the continent. A theory was published in the year 1638, by Galileo, on the resistance of solids, and subsequently by many other philosophers. But however plausible these investigations appeared, they were more theoretical than practical, as will be seen in the sequel. It is only by deriving a theory from care- ful and well-directed experiments, that practical results can be obtained. It would be useless to enumerate the labours of those philosophers, who in following, or varying from, the steps 968 S T R S T R. DICTIONARY OF MECHANICAL SCIENCE, of Galileo, have merely tended to obscure a subject, respecting which they had no data to proceed upon. It is sufficient to enumerate the names of those who, in conjunction with our own countrymen, have added their labours to the little know- ledge we possess. The experiments of Buffon, recorded in the Annals of the Academy of Sciences at Paris, in the years 1740 and 1741, were on a scale sufficiently large to justify every con- clusion, had he not omitted to ascertain the direct and absolute strength of the timber employed. It, however, appeared from his experiments, that the strength of the ligneous fibre is nearly in proportion to the specific gravity. Muschenbroeck, whose accuracy (it is said) entitled him to confidence, made a number of experiments on wood and iron, which, by being tried on various specimens of the same materials, afforded a mean result considerably higher than any other previous authorities. Experiments have also been made by Mariotte, Varignon, Per- ronet, Ramus, Rondelet, Gauthey, Navier, Aubry, and Texier "de-Norbeck, as also at the Ecole Polytechnique, under the direc- tion of M. Prony. With such authorities before us, it might be deemed presumption in me, to offer a communication on a subject which had been previously treated of by so many able men.* But whoever has had occasion to investigate the prin- ciples upon which any edifice is constructed, where the combi- nation of its parts is more the result of uncertain rules than sound principle, will soon find how scanty is our knowledge on The desire of obtaining some approximation, which could only be accomplished by repeated a subject so highly important. trials on the substances themselves, induced me to undertake the following experiments. Description of the Apparatus. (See the Plate.)--A bar of the best English iron, about ten feet long, was selected, and formed into a lever (whose fulcrum is denoted by f). The hole was accurately bored, and the pin turned, which suffered it to move freely. The standard A was firmly secured by the nut c to a strong bed-plate of cast iron, made firm to the ground. The lever was accurately divided in its lower edge, which was made straight in a line, with the fulcrum. A point, or division, D, was selected, at five inches from the fulcrum, at which place was let in a piece of hardened steel. The lever was balanced by the balance weight E, and in this state it was ready for operation. But in order to keep it as level as possible, a hole was drilled through a projection on the bed-plate, large enough to admit a stout bolt easily through it, which again was pre- vented from turning in the hole by means of a tongue t, fitting into a corresponding groove in the hole. So that, in order to preserve the level, we had only to move the nut to elevate or depress the bolt, according to the size of the specimen. But as an inequality of pressure would still arise from the nature of the apparatus, the body to be examined was placed between two pieces of steel, the pressure being communicated through the medium of two pieces of thick leather above and below the steel pieces, by which means a more equal contact of surfaces was attained.* The scale was hung on a loop of iron, touching the lever in an edge only. I at first used a rope for the balance- weight, which indicated a friction of four pounds, but a chain diminished the friction one half. Every moveable centre was well oiled. Of the resistances opposed to the simple strains which may disturb the quiescent state of a body, the principal are the repulsive force, whereby it resists compression, and the force of cohesion, whereby it resists extension. On the former, with the exception of the experiments of Gauthey and Ronde- let on stones, and a few others on soft substances, there is scarcely any thing on record. In the memoir of M. Lagrange, on the force of springs, published in the year 1760, the moment of elasticity is represented by a constant quantity, without indicating the relation of this value to the size of the spring: but in the memoir of the year 1770, on the forms of columns, where he considers a body whose dimensions and thickness are variable, he makes the moment of elasticity proportional to the fourth power of the radius, in observing the relations of theory and practice to accord with each other. This was admitted by Euler in his memoir of 1780, in his elaborate investigation of the forms of columns. . . Mr. Coulomb had, however, shewn before that time, how inapplicable all these calculations were to columns under common circumstances; and similar obser- Vations have been made in subsequentlectures on natural philo- sophy. The results of experiments have also been equally dis- cordant; since it is deduced from those of Reynolds, that the power required to crush a cubic quarter of an inch of cast iron is 448000 lbs. avoirdupois, or 200 tons; whereas by the average of thirteen experiments made by me on cubes of the same size, the amount never, exceeded 10392:53 lbs. not quite five tons. This may be seen by referring to the tables. %. were four kinds of iron used, viz., 1st. Iron taken from the centre of a large block, whose crystals were similar in appearance and magnitude to those evinced in the fracture of what is usually termed gun-metal. 2dly. Iron taken from a small casting, close- grained, and of a dull gray colour. 3dly. Iron cast horizontally in bars of # inches square, 8 inches long. 4thly. Iron cast vertically, same size as last. These castings were reduced equally on every side to # of an inch square : thus removing the hard external coat usually surrounding metal castings. They were all subjected to a gauge. The bars were then presumed to be tolerably uniform. The weights used were of the best kind that could. be procured, and as the experiment advanced, smaller weights were used. Experiments on Cast-Iron in Cubes of # of an Inch, &c.—Iron taken from the block whose specific gravity was 7.033. 'Averages. lbs. avoirdupois- . . ( &X # . . . . . . . . . . tº a gº tº g º º tº e º & º º tº ſe e º e º 'º . . . . . . . 1454 1439.66 {i. # . . . . . . . . . . . . . . . . . . . . . . . . . . . tº º e º sº º ſº gº 1416 #X # . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1449 On specimens of different lengths. Specific gravity of iron 6'977. - #x3 . . . . . . . . . . . © e º e s is • * * * * * * * * * * * * * * * * * * 1922 2116 }}: e e º e º a dº tº º is s e º ºs & © tº G & º ºs e º e s e e s & e s e e a e . 2310 . . ſix # slipped with 1863 lbs. filed flat, and crushed with . . . . . . . . . . . . . . . . . . . . . . 2363 # X 3 ditto, . . . . . ... 1495, ditto . . . . . . . . . . . . 2005 1758-5 if: ditto, . . . . . . . . . . . . * * * * * * * * * g º e º º . . . . / 1407 # × 3 ditto, . . . . . . . . . . . . . . . tº tº 4 g º is ºf ſº tº g º de g º º 1743 #X # ditto, . . . . . . . . . . . & e º ºs e º ºs tº g º ºn tº º ſº tº dº tº . 1594 U$x # ditto, . . . . . . . . . . . . . . . . . . . . . . . . tº e º º 'º º 1439 April 23, 1817. Experiments on Cubes of 4 of an Inch, taken from the Block. # × # º tº * @ Q a e e º e tº de e º tº º * > * * * * e e gº 10561 tºº º # X # © e º ſº tº e º e G & ºl e e s s a s & e º º ſº º e s tº tº ſº 9596 97735 3:2; ...................... tº e º gº tº e º e tº e º e 9917 #X # . . . . . . . . . . . . . . . dº º º º & e º 'º e o a . . . . . . . . . . 9020 * It is true that the subject has been considered by many able philoso- sophers, from Galileo down to the present period; but it is only lately that the proper object of attention has been ascertained ; or at least the results of their inquiries had not been brought forward in a practicable form. For when Dr. T. Young published his Lectures, there was little on the subject besides the intricate, and I may add unsatisfactory, investigations of Euler and Lagrange. As to the resistance to fracture, which with the greater part of mechanical writers is the only object attended to, it is of very inferior im- portance.—The laws of flexure constitute the chief guide in the construction of buildings: and the intention of these notes is to call the attention of experi- mentalists to this part of the subject: and as it is probable the ingenious author of the experiments now before me may be tempted to resume his labours, I feel certain that he will not feel displeased to have his attention called to-some interesting points of inquiry, which he has either omitted to hotice, or has not given to the public.—T. T. - -w # This machine must have had a considerable degree of friction, and Mr. Reinié has flot, apparently, attempted to determine the quantity: it must however have been very great in the high pressures. The lever turned upon a pin similar to that used by Gaúthey, (Rozier's Journal de Physique, tome iv. p. 403,) which Perronet found to have much friction, and to cause great irregularity. To remedy the defects of this machine, another was contrived by Rondelet, in which he attempted, and it appears successfully, to obviate the most material defects of the old one. The action was more equal on the compressed surface, and a more accurate measure of the strength was obtained. Rondelet's machine is described in his Traité Theorique et Prac- tique de l'Art de Bátir, tome iii. p. 79.-T. T. t - # It is probable that Mr. Reynolds made his experiments on metal cast at the furnace of Maidley Wood, which is of a very strong and superior quality; but this circumstance can have been but of little importance com- pared to the great disproportion of the results.--T. T. *. Mºyº 's ºx/º/, /º/M ſºvº. 2, º/, Sººyººſ ºr Mºlºſ. Lºs Joº. *__ —iº - =/ = \ - ||||}|| | e- //w of the Wºzº E. = //e Zºº of the Zever is now whewn # | --- ºr | == - ºw, ºr one haſ ºr nº whº ºr - - - º º - - º - - S T R. S T R. 969 DICTIONARY OF MECHANICAL SCIENCE. Castings, Horizontal. Specific Gravity 7-113. lbs. avoirdupois. #x + . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1943? - x + . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19799 10114 3: .................................... º. C#x3 ......... . . . . . . . . . . . . . . . . . . . . . . . . . . . 8699 - Vertical Castings. Specific Gravity 7-074. ſ}x + bottom of vertical bar. . . . . . . . . . . . . . . . 12665 | 3 × 3. . . . . . . . . . . . . . . . e s e e s c e s e g º e º e º e º e º 'º e º *R.J #X # . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . * * * 11136763; ; ; ;.................... . . . . . . . . . . . . . 98.44 [ix # full size. Scale broke with 10294; tried again...... . . . . . . . . . . . . . . . . . . . . 11006 A prism, having a logarithmic curve for its limits, re- sembling a column; it was # of an inch diameter by one inch long, broke with . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6964 April 28th. Trials on Prisms of different Lengths, * #x & horizontal . . . . . . . . . . . . . . . . . . . . . . . . . . 9456 9414'5 ###!";:::::::::::::::: 9374 #x3 ditto, bad trial, 9006 lbs. e #x # vertical . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9938 99.825 tº ditto................ . . . . . . . . . . . . . . . . 10027 April 29th. Horizontal Castings. #X # . . . . . . . . . . . . . . . . . . . . . . . . . . . • * * * * * * * is e . 9006 4×{ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8846 #x # . . . . . . . . . . . . . . . . . . . . . . . . e e º 'º tº e e . . . . . . . 8362 3 × # . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6430 3 × 3 or one inch long . . . . . . . . . . . . . . . . . . . . . . . 6321 TVertical Castings. %x # . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9328 # × # . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8885 #x ; a small defect in the specimen . . . . . . . . . . 7896 # X # . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7018 4 × 3 or one inch. . . . . . . . . . . . . . . . . . . . . . . . . . . . . *6430 Earperiments on different Metals. . # x 4 cast copper, crumbled with . . . . . . . . #x + fine yellow brass reduced tº with 32.13° 3 with.... # × # wrought copper, . . . . . . . . . . . . . 3427 & . . . . . . .. 6440 # × 4 cast tin, . . . . . . . . . . . . . . . . . . . . . 562 & . . . . . . . . 966 # × 3 cast lead, . . . . . . . º, . . . . t 483 The anomaly between the three first experiments on # cubes, 73.18 10304 • * * * * * * * * * * * * * * * * * * Tº • * * * and the two second of a different length, can only be accounted for, on the difficulty of reducing such small specimens to an equality. The experiments on # inch prisms of different lengths give no ratio. The experiments on # inch cubes, taking an average of the three first in each, give a proportion between them and the three on # cubes, - as 1 : 6-096 in the block castings as 1 : 7'352 in the horizontal ditto, as 1 : 8'035 in the vertical ditto, in several cases the proportion is as the cubes.—The vertical cube castings are stronger than the horizontal cube castings.-- The prisms usually assumed a curve similar to a curve of the third order, previous to breaking. The experiments on the different metals give no satisfactory results. The difficulty con- sists in assigning a value to the different degrees of diminution. When compressed beyond a certain thickness, the resistance becomes enormous. - Experiments on the Suspension of Bars.-The lever was used as in the former case, but the metals were held by nippers, as indicated in the drawing No. 2. They were made of wrought irón, and their ends adapted to receive the bars, which, by being tapered at both extremities, and increasing in diameter from the actual section, (if I may so express it,) and the jaws of the nippers being confined by a hoop, confined both. The bars, which were six inches long, and # square, were thus fairly an firmly grasped. - April 30, 1817 TNo. lbs. 45 # inch, cast-iron bar, horizontal...... 1166 •= 46 # do. do. vertical ....... 13 is 11986 47 do. cast steel previously tilted ...... 8391 48 # do. blister steel, reduced per hammer 8322 49 # do. shear steel, do. do. ...... 7977 50 + do. Swedish iron, do. do. . . . . . . 4504 51 + do. English iron, do. do. . . . . . . 3492 52 + do, hard gun-metal,mean of two trials 2273 53 + do. wrought copper reduced per & 2112 hammer . . . . . . . . . . . . . . . . . . $ 54 + do. Cast copper . . . . . . . . . . . . . . . . . . . 1.192 55 + do. fine yellow brass. . . . . . . . . . . . . . 1123 56 # do. cast tin . . . . . . . . . . . . . . . . . . . . . . 296 57 # do. cast lead . . . . . . . . . . . . . . . . . . . . . 114 Remarks on the last Experiments.-The ratio of the repulsion of the horizontal cast cubes to the cohesion of horizontal cast bars, is 8:65 : 1. The ratio of the vertical cast cubes to the cohesion of the vertical cast bars, is as 9'14 : 1. The average of the bars, compared with the cube, No. 16, is as 10.6l 1 : 1. The other metals decrease in strength, from cast steel to cast lead. - The stretching of all the wrought bars indicated heat.* The fracture of the cast bars was attended with very little diminution of section, scarcely sensible. - The experiment made by M. Prony, (which asserts, that, by making a slight incision with the file, the resistance is dimin- ished one half) was tried on a 4 inch bar of English iron ; the result was 2920 lbs., not a sixth part less. This single experi- ment, however, does not sufficiently disprove the authority of that able philosopher, for an incision is but a vague term. The incision I made might be about the 40th part of an inch. Experiments on the Twist of 3 Inch Bars.—To effect the ope- ration of twisting off a bar, another apparatus was prepared: it consisted of a wrought-iron lever two feet long, having an arched head about 1-6th of a circle, of four feet diameter, of which the lever represented the radius, the centre round which it moved had a square hole made to receive the end of the bar to be twisted. The lever was balanced as before, and a scale hung on the arched head; the other end of the bar being fixed —w * In these experiments, the results are so irregular, that no practical con- clusions can be derived from them. There are many circumstances that affect the results of such experiments, which were observed by Gauthey ; such as the position of the specimen, the form of its surfaces, and the in- equality of the different specimens—which were so extremely small, that it would be scarcely possible to obtain any tolerable degree of accuracy. Gauthey's experiments exhibit a like irregularity, indicating no relation between the height of the piece and its resistance, (Rozier's Journal, tome iv. p. 407.) It appears probable that when the fracture is of that kind where the body decomposes into pyramids, the length does not influence the result, provided that the piece be long enough to admit of the free motion of the fractured parts. I imagine that hard cast iron breaks into pyramids, but the nature of the fracture Mr Rennie has not stated. Probably it was so soft as to break in the manner of flexible bodies, in which, though the forces must act according to some regular law, it is difficult to trace their operation in a continuous solid.—T. T. f The degree of compression of these bodies having been observed, we might conclude that the height of the modulus of elasticity might be ob- tained from these experiments. This, however, is not the case ; and so far proves that the strain is not of that simple kind which it has been supposed to be. The reduction of length might be easily measured, even in hard bodies, by an apparatus for multiplying its extent ; and it would throw much 103. light on the subject, to reduce pieces of the same length but of different areas to a given length. Such a set of experiments would be infinitely more valuable than those on the fracture, and much more easily made, as the apparatus would be easier to manage. - The importance of the laws of stiffness over those of strength bas been ably stated by Dr. Young, (Lectures on Natural Philosophy, vol. 1.) and what he has stated in favour of stiffness applies equally to the mode of ex- perimenting I now recommend, which could not fail of establishing some important practical rules.—T. T. - # Mr. Rennie's apparatus did not permit of measuring the extension of the specimens. In some experiments made by Mr. Telford, (Barlow's Essay on the Strength of Timber, &c. p. 230,) where the extension was mea- sured, it appears to have been greatest at the middle of the length, and to increase from the ends towards the middle in a ratio sensibly proportional to the square of the distance from the end. This fact is at variance with the received opinion respecting the strain. Dr. Thomson has remarked, (Annals of Philosophy, vol. xii. p. 450) that the strengths of English and Swedish iron are not in the same proportion as is found by comparing Count Sickengen's with that described in the Annals for April 1816. But if I do not mistake, Sickengen's was made on wire, and consequently would be higher, as the strength is always much increased, by forging, wire-drawing, &c.—T. T. - 11 O 970 S T R. , S T R. DICTIONARY OF MECHANICAL SCIENCE. in a square hole in a piece of iron, and that again in a vice, The undermentioned weights represent the quantity of weight put into the scale. - May 30, 1817. On Twists close to the bearing, cast horizontal. No. - - lbs. oz. 58 + in bars, twisted as under with ...... 10 14 in the scale. 59 + do. bad casting. . . . . . . . . . . . . . . . . . . . 8 4 60 3. do. • , , , . . . . . e s - e s e s • * * * * * * * * * * * * * 10 11 . Average 9 15 Cast vertical. 61 + . . . . . . . . . . . . . is a s a e e s e e o e º 0 ° º º ... ... 10 8 62 + . . . . . . . . . . . . . . . . . . . . . . e is e º O ſº º º . IO 13 63 + . . . . . . . . . . . . . . e e º ſº e s tº & © tº e º 'º ... 10 11 10 iO On different Metals. 64 Cast steel---------------- * * tº E tº º - - 17 9 65 Shear steel - - - - - - - - - - - - - - - - . . . . -- 17 1 66 Blister steel -- - - - - - - - - - - - - - - - - - - - - 16 11 67 English iron, wrought - - - - - - - - - - - - - - 10: 2 68 Swedish iron, wrought -- - - - - - - - - - - - - 9 8 69 Hard gun-metal. ... - - - - - - - - sº º ºs ºs ºn tº sº º 5 0 70 Fine yellow brass - - - - - - - - - - - - ------ 4 11 71 Copper, cast- - - - - - - - - - - - - - - - - - - - - - 4 5 72 Tin --------------- sº as a sm as ºr ºn as as ºn tº ſº º 1 7 73 Lead.---------------------------- 1 () On Twists of different Lengths. Horizontal. Vertical. . . - No. Weight in Scale. No. Weight in Scale. 74 + by } long 7 3 77 3 by # do. 10 1 75 + by # do. 8 1 78 # by 3 do. 5 9 76 + by 1 inch do. 8 8 79 by 1 inch do. 8 5 Horizontal Twists at 6 from the bearing. 80 + by 6 inches long - - - - - - - - - - - - - - - - - - - - - - - - - - Í0 9 81 % by do. do. -- - - - - - - - - - - - - - - - - - - - - - - - - - - - - 9 4 82 # by do. do. -- - - - - - - - - - - º, º an as as sº se e s sº as as * * * * * * 9 7 Twists of , inch square bars, cast horizontally. qrs. Ibs, oz. - 83 close to the bearing ...... 3 9 12 end of the par hard. 84 & do. ------------ gº º ºs ºs º gº 2 18 O middle of the bar. 85 # at 10 inches from bearing, } 1 24 0% On Twists of different Materials. These experiments were made close to the bearing, and the weights were accumulated in the scale until the substances were wrenched asunder. No Weight of Scale. No. Weight of Scale. 86 Cast steel - - - - - - - - 19 9 91 Hard gun-metal -- 5 0 87 Shear steel - - - - - - 17 1 92 Fine yellow brass. - 4 11 88 Blister steel ... - - - - 16 T 1 93 Copper - - - - - - - - - - 4 5 89 English iron, No. 1. 10 2 94 Tin - - - - - - - - - - - - 1 7 90 Swedish iron - - - - - - 9 8 96 Lead - - - - - - - ... t 1 0 Remarks.—Here the strength of the vertical bars still pre- dominates. The average of the two taken conjointly, and com- pared with a similar case of 3 inch bars, gives the ratio as the cubes, as was anticipated. In the horizontal castings of dif. ferent lengths, the balance is in favour of the increased lengths; but in the vertical castings, it is the reverse. In neither is there any apparent ratio. In the horizontal castings at 6 inches from the bearing, there is a visible increase, but not so great as when close to the bearing. June 4, 1817. Miscellaneous Eaſperiments on the Crush of One * - Cubic Inch. No. lbs. avoidupois. 96 Elm -------------------------------------- 1842 97 American pine------------------------------ 1606 98 White deal -------------------------------- 1928 99 English oak, mean of two trials -- - - - - - - - - - - - - - - 3860 100 Ditto, of 5 inches long, slipped with - - - - - -...----- 2572 101 Ditto, of 4 inches ditto ------ - - - - - - - - - - - - - - - - 5 147f 102 A prism of Portland stone 2 inches long - - - - - - - - 805 103 Ditto, statuary marble - - - - - ----------------- 3216 104 Graig Leith ------------------------ - - - - - - - - 8683 In the following experiments on stones, the pressure was communicated through a kind of pyramid, the base of which rested on the hide leather, and that on the stone.' The lever pressed upon the apex of the pyramid. Cubes of one and a half inch. - No. Spec. grav. Ibs. avoir. 106 Chalk ---------------- * * * * * * * * * * * as 1127 106 Brick of a pale red colour - - - - - - - - - - - - 2'085 1265 107 Roerstone, Gloucestershire - - - - - - - - - - - - 1449 108 Red brick, mean of two trials -- - - ...... 2-168 1817 109 Yellow face-baked Hammersmith paviors 3 times 2254 110 Burnt do. mean of two trials - - - - - - - - - - 3243 111 Stourbridge or fire brick - - - - - - - - - - - - 3S64 112 Derby grit, a red friable sand-stone ..... 2.316 7070 113 Ditto, from another quarry . . . . . . . tº tº ſº ſº tº g tº 2'428 9776 114 Killaly white freestone, not stratified . . . . . 2,423 10264. 115 Portland. . . . . . . . . . . . . . . . . gº tº e º ſº e º e g º e º º 2°428 10284. 116 Craig Leith, white freestone ............. 2,452 12346 June 5th, 6th, and 7th, 1817. No. Spec. gray, lbs. avoir. 117 Yorkshire paving with the strata . . . . . . 2-507 12856 118 Ditto do. against the strata..... tº e º g º e º e 2-507 12856|| 119 White statuary marble not veined . . . . . . 2:760 T 3632 120 Bramley Fall sandstone, near Leeds, e. º Strata . . . . . . . . . . . . . . . . . . . . . .° 2'505 13632 121 Ditto, against the strata . . . . . . . . . . . . . . . 2°506 13632 122 Cornish granite . . . . . . s • * e e s e o e e º a '• e o e 2.662 14302 123 Dundee sandstone or brescia, two kinds 2,530 14918 124 A two-inch cube of Portland. . . . . . . . . . . . 2'423 I4918 125 Craig Leith with the strata ............. 2'452 15560 126 Devonshire red marble, variegated . . . . . . - 167] 2 127 Compact limestone . . . . . . . . . . . . w e º e º a s . 2'584 17354. 128 Peterhead granite hard close grained.... 18636 129 Black compact limestone, Limerick .... 2'598 19924 130 Purbeck. . . . . . . . . . . . . . . . . . . . . ſº tº e º gº tº e º ºs 2'599 206] () 131 Black Barbant marble . . . . . . . . . . . . . . . . 2-697 20742 132 Very hard freestone . . . . . . . . . . . . . . . . . . 2'528 21254 133 White Italian veined marble . . . . . . . . . . 2,726 21783 134 Aberdeen granite, blue kind.......'..... 2:625 24556'ſ * In the resistance to twisting, there are some doubts by different writers expressed respecting the effect of the length : these experiments, however, do not appear calculated to remove them ; they are so extremely irregular. The angle of torsion was not observed, though it certainly would not have been difficult to have done so in the longer pieces. Some experiments on larger specimens are described in Thomson's Annals for March 1819; but we cannot compare them with these, for want of a more correct knowledge of the nature of this strain.—T. T. - . f These experiments are merely a repetition of those in a preceding page, experiments 64 to 73; except that here cast steel is stated to be 19 lbs. 90Z. instead of 17 lbs. 9oz. # The experiments on wood are considerably below those of other writers ; and it appears singular that the four-inch specimen should be stronger than the shorter length. According to Rondelet’s experiments to crush a cubic inch of oak it required from 5000 to 6000lbs. avoirdupois. In the former the pieces were compressed 1-3d of their length; in the latter, one half of their length (Rondelet’s L’Art de Bátir, tome iv. p. 67.) Mr. Rennie has not stated the diminution of length.--T. T. § It certainly would have been preferable to have placed a hard and rigid substance next the stone, in order to secure equality of pressure.—T. T. | Gauthey tried the stones in different positions in respect to their natural beds ; but from a general view of his experiments, it does not appear that he was correct in concluding them to be stronger when “posées en delit,” because his comparison is made between means that include sections of very different forms. (Rozier's Journ. tome iv. p. 406.)—T.T. fir - sº from 6000 to 7000 lbs. *| According to Gauthey's experiments, a cubic inch of brick, specific gravity 1-557, was crushed by 1562 lbs, avoirdupois. of Flanders marble . . . . 2:628 13142 of Genoese do. . . . . . . . . 2-700 4856 of porphyry . . . . . . . . . . 2.871 . . . . . . . . . . . . . , 35568–T. T tº º º is tº gº e º 'º C tº e º 'º S T R S T R. 971. DICTIONARY OF MECHANICAL SCIENCE. * N. B. The specific gravities were taken with a delicate ba- lance, made by Creighton of Glasgow; all with the exception of two specimens, which were by accident omitted.* Remarks.—In observing the results presented by the preced- ing table, it will be seen that little dependence can be placed on the specific gravities of stones, so far as regards their repul- sive powers, although the increase is certainly in favour of their specific gravities. But there would appear to be some unde- fined law in the connexion of bodies, with which the specific gravity has little to do. Thus, statuary marble has a specific gravity above Aberdeen granite, yet a repulsive power not much above half the latter. Again, hardness is not altogether a characteristic of strength, inasmuch as the limestones, which yield readily to the scratch, have nevertheless a repulsive power approaching to granite itself.t It is a curious fact in the rupture of amorphous stones, that pyramids are formed, having for their base the upper side of the cube next the lever, the action of which displaces the sides of the cubes, precisely as if a wedge had operated between them. I have preserved a number of the specimens, the sides of which, if continued, might cut the cubes in the direction of their diagonals. Experiments made on the transverse Strain of cast Bars, the Ends 150 A feather-edged or J. bar, whose dimensions were 151 } 2 inches deep by 2 wide 10 0 edge up , 2 8 152 & Half of ditto. N. B. All these bars contained the same area, though differ- ently distributed as to their forms. Experiments made on the Bar of 4 Inches deep by + Inch thick, by giving it different Forms, the Bearings at 2 Feet 8 Inches, as 3105. before. No. Ibs. lbs. 153 Bar formed into a semi-ellipse, weighed 7 4000 154 Ditto, parabolic on its lower edge 2 3 3860 Ditto, of 4 inches deep by + inch thick 3 y 3979 Experiments on the transverse Strain of Bars, one end made fast, Weight being suspended at the other, at 2 feet 8 inches from the the Bearing. lbs. 155 An inch square bar bore -------- - - - - - - - - - - ,, 280 156 A bar 2 inches deep, by § an inch thick - - - - - - 25 539 157 An inch bar, the ends made fast -- - - - - - - - - - - 5 y 1173 The paradoxical experiment of Emerson was tried which states that by cutting off a portion of an equilateral triangle, )see page 114 of Emerson's Mechanics,) the bar is stronger than before, that is, a part stronger than the whole ! The ends were loose at 2 feet 8 inches apart as before. The edge from which the part was intercepted was lowermost, the weight was applied on the base above, it broke with 1129 lbs. whereas in the other case it bore only 840 lbs. - Remarks on the Transverse Strain–Banks makes his bar from the cupola, when placed on bearings 3 feet asunder, and the ends loose, to bear - - - - - - - - * - tº * * * * * * * * * * = as an as as as - 864 lbs. Now, all my bars were cast from the cupola, the difference was therefore -------------- * † = ſº º is ºn me tº ºn tº me as sº sº º sº me 33 lbs. I adopted a space of 2 feet 8 inches asunder, as being more convenient for my apparatus. The strength of the different bars, all cases being the same, approaches nearly to the theory which makes the comparative values as the breadths multiplied into the squares of the depths. The halves of the bars were tried merely to keep up the analogy. The bar of 4 inches deep, however, falls short of theory by 365 lbs. It is evident we can- not extend the system of deepening the bar much further, nor does the theory exactly maintain in the case of the equilateral triangle by - - - - - - - tº º ºs ºs º ºs º ºs º º tº gº tº ſº tº tº sº tº ºm º º ºs ºr nº º - - 243 lbs. Dr. Young has calculated the height of the modulus of elasticity from this statement, (Nat. Phil. vol. ii. art. 326,) but it is well known, that the deflex- ion is not regular when the piece is nearly broken. In Banks’s experi- ments on curved bars, the deflexion is given, but the thickness of the bars is not stated. It is true, Rondelet has made some experiments on cast-iron, where the successive deflexions were registered, but these experiments are not very regular ; besides, it would be desirable to have experiments on British iron. u - As I have two experiments by me, I shall take this opportunity of laying them before my readers. A bar of cast-iron, from a Welsh foundry, which did not yield easily to the file, was laid upon supports exactly three feet apart; the bar was an inch square, and when 308 lbs. were put into a scale suspended from the middle of its length, the deſlexion was found to be 3-16ths of an inch ; whence the height of the modulus of elasticity is 6,386,688 feet. The experiment was made by Mr. R. Ebbels, at Garnons, near Hereford. A joist of cast-iron 9 inches deep, resembling in form the letter I, was laid upon supports 19 feet apart, first on its edge, when the deſlexion from its own weight was 3-40ths of an inch. It was then laid flatwise, and the deflexion from its own weight was 3; inches. The castings were from Messrs. Dowson's foundry, Edgeware Road. The iron yielded easily to the file. The beight of the modulus of elasticity, according to the experiment on the joint flatwise, is . . . . . . . . 5,100,000 feet. on the edge is... . . . 5,700,000 — The deflexion being very small when the joist was on its edge, perhaps it loose. June 8th, 1817.j. Weight of bars. dist. of bearings. Ibs. Ibs. oz. ft. avoir. 135 Bar of 1 inch square . . . . . . . . . . . . 1 () 6 3 0 897 136 Do. of 1 inch do. . . . . . . . . . . . . . , 9 8 2 8 1086 137 & Half the above bar ............ 8 4 2320 138 C Bar of 1 inch square, through the } diagonal . . . . . . . . . . . . . . . . . . 2 2 8 851 139C Half the above bar . . . . . . . . . . . . 1 4 1587 140, Bar of 2 inches deep, by # inch - thick . . . . . . . . . . . . . . . . . . . . 5 2 8 21.85 141 C Half the above bar . . . . . . . . . . . . l 4 4508 142 ; Bar 3 in. deep, by § inch thick . . 9 15 2 8 3588 143 & Half the bar . . . . . . . . . . . . . . . . . e 1 4 6854 144 Bar 4 inches, by + inch thick..... 9 7 2 8 3979 145 Equilateral triangles with the angle up and down. 146 ( Edge or angle up . . . . . . . . . . . . . . 9 11. 2 8 1437 147 angle down . . . . . . . . . . . . 9 7 2 8 840 148) Half the first bar . . . . . . . . . . . . . . 1 4 3059 149 GPHalf the second bar. . . . . . . . . . . . - 1 4 1656 * Mr. Rennie has, of course, taken the specific gravity in the usual man- ner, but certainly not the real specific gravity of the stone in any of the porous ones, though it may be that of the material the stone is composed of. When a stone is porous—and many building stones are very much so—it will be found that the specific gravity, as usually obtained, is not the weight of a | cubic foot in ounces avoirdupois, which it certainly ought to be, and par- ticularly where the information is intended for the use of practical men. If Mr. Rennie were to try any of his specimens, he would find the weight of a cubic foot much below the numbers he has given in the case of brick, oolite, and sandstones. The specific gravity of a minute concretion of Port- land stone may be 2-432, or, as Kirwan has it, 2.461, but that of the stone itself is much lower. Were the real specific gravity of porous stones taken, their eomparative heaviness would become a more decisive mineral character than it is according to the present method, and the correction presents no difficulty.—T. T. f A curious circumstance was observed by Rondelet in his experiments; viz. that the blocks from the middle of a stratum of stone were of a higher specific gravity than those taken either from the upper or lower part of the stratum. The stones were from Chatillon, Bagneux, &c. He also observed, that in the same kind of stone the strength was as the cube of the specific gravity. (L’Art de Bátir, tome iii. p. 83, et suiv.) That any relation should exist between the specific gravity and strength of stones of different kinds was not to be expected, as strength depends on other properties.—T. T. # It is in these experiments that we have most to regret the want of observations, and those of a nature that would have added little to the labour which all, who make such experiments, must undergo. It is, however, a labour that is, to a mind engaged in the search of knowledge, more pleasing than those unaccustomed to such feelings, can conceive. But too often it is a pleasure that cannot be pursued, except at an expense and encroachment on the hours of business which a professional man can ill afford to indulge in. The defect of these experiments consists in the want of observations on the flexure produced by given weights, particularly in the first degrees of deflexion; and it is the more to be regretted, because we have very few experiments on cast-iron, where such observations have been made. Banks states, that his specimens bent about an inch at the time of fracture ; aud was not measured with the necessary degrees of accuracy, as a very small error would cause the difference in the result. The following table con- tains the value of the modulus for cast-iron, according to the experiments above stated. - - º Height of Modulus in feet. Experimentalists. Cast-iron (Welsh). . . . . . . . . . 6,386,688 bbels. Cast-iron . . . . . . . . . . . . . . . . 3,500,000 Banks. Cast-iron, gray French . . . . . . 5,095,480 Rondelet.* Cast-iron, soft do. . . . . . . . . 4,247,000 Rondelet.* Cast-iron . . . . . . . . . . . . . . . . . . 5,700,000 By my trial,—T.T * L'Art de Bátir, tome iv. part ii. p. 514. 97.2 S T R. S T R. DICTIONARY OF MECHANICAL SCIENCE. The diagonal position of the square bar is actually worse than when laid on its side, contrary to many assertions.” The same quantity of metal in the feather-edged bars was not so strong as in the 4-inch bar. - The semi-elliptic bar exceeded the 4-inch bar, although taken out of it. The parabolic bar came near it. The bar made fast at both ends, I suspect must have yielded, although the ends were made fast by iron straps. The experiments from Emer- son on solids of different forms might be made ; but the time and trouble these experiments have already cost, have compel- led me to relinquish further pursuits for the present. If, how- ever, in the absence of better, they are worthy of the indulgence of the Royal Society, it will not only be a consolation to me that my labours merit their attention, but a further inducement to prosecute the investigation of useful facts, which even in the present advanced state of knowledge will yet admit of addition. It has been observed by professer Leslie, that the strength of materials is exerted in four different ways: 1. In sustaining a longitudinal tension; 2. In withstanding a longitudinal compres- sion; 3. In resisting a transverse pressure; and, 4. In opposing the act of twisting or wrenching 1. Longitudinal Tension.—The tension which a stone pillar, a bar of metal, a beam of wood, or even a hempen rope, can bear when pulled lengthwise, must evidently depend upon the cohesion of any cross section. As the material stretches out, the longitudinal-attraction of the particles becomes augmented. This increase, at first, is proportional to the dilatation, but it afterwards advances very slowly, and a small additional strain is then sufficient to produce that limit of extension which occa- sions total fraeture or disruption of the column. Its length will nowise affect the utmost strain which it can bear, this being determined merely by the smallest cross section where the dis- location of the particles will take place. Let Z. A be a prism stretched in the direction of its length. The particles of the section B will be zE pulled from those of the section C, till an attrac- tion be generated equal to the whole tension. But the particles of the section C, must settle in equili- brium, and are consequently drawn back by an equal force. In this acquired position, therefore, they must attract the particles of the section D, with the . . . . same force. The original tension is thus transferred E. . . . successively to the extremity Z, where it is finally D. . . . exerted, the effect of its action being neutralized in c. . . . all the intermediate sections. |B • * * * The cohesive power thus evolved, is hence the ac- * * * * cumulative attraction of all the particles in any sec- * That a square bar was weakest in the direction of its diagonal, I had from theory determined some time ago, and the investigation is given in the Phil. Mag. vol. L. p. 418; and it is very satisfactory to find it couſirmed by these experiments, and also by those of Mr. Barlow. It is not an easy task to make accurate experiments on triangular bars, as it is difficult to protect the angle, unless a kind of saddle be used, which must affect the result.—T. T. - # The science of construction is yet in its infancy, and certainly requires many additions. The first experiments on the strength of materials appear to have been made before the Royal Society; and there can be no doubt that a favourable reception will be given to any others that will tend to elucidate a subject, which is likely to form one of the principal branches of an engineer's education : as he must either proceed on the principle of science, or be directed by a feeling of fitness, which is to be acquired only by devoting a life-time to the practice of his art. It is to be hoped that Mr. Rennie will speedily bring forward some additions to the valuable experiments he has already made, with more detailed descriptions of the phenomena observed in the course of his labours. The example of the chemists ought to be followed, as it is not the number but the accuracy and correct description of experiments that constitute their value. Mr. Barlow has represented some of the fractures in his experiments by engravings, which is certainly an excellent plan. In Evelyn's Sylva, (Dr. Hunter’s edition, vol. ii. p. 227,) it is stated, that a treatise on duplicate proportion was published by Sir William Petty, in which is “A new hypothesis of elastic or springy bodies, to shew the strengths of timbers, and other homogeneous materials, applied to buildings, machines, &c.” I have never been able to procure the work; but if any of your cor- respondents could furnish a sketch of this “new hypothesis,” it would be a desirable addition to the history of this branch of science; as, if it should accord with Evelyn's description, our countryman will rank amongst the first contributors to the resistance of solids.-T. T. tion. The corresponding longitudinal distention is at first pro- portional to it, but afterwards increases in a more rapid pro- gression. Thus, a bar of soft iron is found to stretch uniform y, by continuing to append to it equal weights, till it be loaded with half as much as it can bear; beyond that limit, however, its extension will be doubled by each addition of the eighth part of the disruptive force. Supposing the bar to be an inch square and 1000 inches in length, 36,000 lbs. avoirdupois would draw it out 1 inch : but 45,000 lb. would stretch it 2 inches; 54,000 lbs. 4 inches; 63,000 lb. 8 inches; and 72,000 lb. 16 inches; when it would finally break, the extension being now eight times great- er than its ordinary rate. Let A B in the annexed figure be a prism or bar of any material, and its prolongation B C express the whole longitudinal force exerted, which occasions the small extension A. a. While the length of this bar B C continues the same, it is evident that a A must be proportional to the distraining weight B C. Make, therefore, a A : B C :: A B : CD; or, alternately, a A : A B : : B C : C D, and C D must be constant. Since BC now bears the same relation to C D as a A to A B, any portion of C D will, by its weight, produce a corre- sponding distension of A. B. Thus a column of the thousandth part of the length of C D would extend A B one thousand part, and the same weight would, by its compression, occasion an equal contraction. The co- lumn CD thus found is called the Modulus of Elasticity; it de- pends entirely on the nature of the cohesive substance, and may be determined by a single experiment. Of the principal kinds of timber employed in building and carpentry, the annexed table will exhibit their respective modul- lus of elasticity, and the portion of it which limits their cohe- sign, or which lengthwise would tear them asunder. Xi B| I) Teak, . . . . . . . . . . . . . . . . 6,040,000 feet, . . . . . . 168th. Oak, ----. . . . . . . . . . . . 4,150,000 feet, ...... 144th. Sycamore, . . . . . . . . . . . . 3,860,000 feet, ...... 108th Beech, . . . . . . . . . . . . . . . . 4,180,000 feet, ...... 107th. Ash, . . . . . . . . . . . . . . . . . . 4,617,000 feet, .... -- 109th. Elm... . . . . . . . . . . . . . . . . 5,680,000 feet, . . . . . . 146th. Memel Fir, . . . . . . . . . ... 8,292,000 feet, . . . . . . 205th. Christiana Deal, . . . . . . 8, 118,000 feet, ...... 146th. Larch, . . . . . . . . . ----. . ‘5,096,000 feet, . . . . . . 121st. A tabular view may likewise be given of their absolute cohe- sion, or the load which would rend a prism of an inch squaré, and the altitude of the prism which would be severed by the action of its own weight. Teak, . . . . . . . . . e 12,915 lb. . . . . . . 36,049 feet. Oak, . . . . . . . . . . . . . . . . 11,880 lb. . . . . . . 32,900 feet. Sycamore, . . . . . . . . . . . . 9,630 lb. . . . . . . 35,800 feet. Beech, . . . . . . . . . . . . . . . . 12,225 lb. . . . . . . 38,940 feet. Ash, . . . . . . . * * * * * * * * * * > 14, 130 lb. . . . . . . 42,080 feet. Plm,. . . . . . . . . . . . . . . . . . 9,720 lb. . . . . . . 39,050 feet. Memei Fir, . . . . . & e º ºs º º . 9,540 lb. . . . . . . 40,500 feet. Christiana Deal, . . . . . . . . 12,346 lb. . . . . . . 55,500 feet. Larch, . . . . . . . . . ... 12,240 lb. . . . . . . 42,160 feet. It is singular, that woods of such diversiſied structure should yet differ so little on the whole in their elasticity and cohesion. Specimens of the same sort will occur, which are sometimes as much varied as the several kinds themselves. The modulus of the elasticity of hempen fibres has not been ascertained, but may probably be reckoned about 5,000,000 feet. Their cohesion is, for every square inch of transverse section, 6,400 lb. The usual mode of estimating the strength of a cable or rope of hemp, is to divide by five the square of its number of inches in girth, and the quotient will express in tons the utmost strain it could bear. But the computation is rather simpler, to double the square of the diameter of the rope. This estimate, how- ever, applies only to new ropes formed of the best materials, not much twisted, and having their strands iaid even. If yarns of 180 yards long be worked up into a rope of only 120 yards, it will lose one-fourth of its strength, the exterior fibres alone resisting the greatest part of the strain. . The register cordage of the late Captain Huddart exerts nearly the whole force of the strands, since they suffer a contraction of only the eighth part in the process of combining. & The metals diſſer more widely from each other in their elastic S T R. S T R. DICTIONARY OF MECHANICAL SCIENCE. 973 * force and cohesive strength, than the several species of wood or vegetable fibres. Thus the cohesion of fine, steel is about I35,000 lb. for the square inch, while that of cast lead amounts only to about the hundred and thirtieth part, or 1800lb. º According to the very accurate experiments of George Rennie in 1817, and already noticed, the cohesive power of a rod an inch square, of different metals, in pounds avoirdupois, with the corresponding length in feet, is as follows: - Cast Steel, . . . . . . . . . . . . 134,256 lb. ... ... 39,455 feet. Swedish Malleable Iron, 72,064 lb. ....... 19,740 feet. English ditto, . . . . . . . . 66,872 lb. . . . . . . 16,938 feet. Cast Iron, . . . . . . . . . . . . 19,036 lb. . . . . . . 6, 110 feet. Cast Copper,. . . . . . . . . . 19,072 lb. . . . . . . 5,003 feet. Yellow Brass, . . . . . . . . 17,958 lb. . . . . . . 5, 180 feet. Cast Tin, ..... . . . . . . . 4,736 lb. . . . . . . 1,496 feet. Cast Lead, . . . . . . . . . . . . 1,824 lb. . . . . . . 348 feet. It thus appears, that a vertical rod of lead, 348 feet long, would be rent asunder by its own weight. The best steel has nearly twice the strength of English soft iron, and this again is about three times stronger than cast iron. Copper and brass have almost the same collesion as cast iron. 2. Longitudinal Compression.—The compression which any column suffers is at first equal to the dilalation occasioned by an equal and opposite strain, being in both cases proportional to the modulus of elasticity. But while the incumbent weight is increased, the power of resistance likewise augments, as long as the column withstands inflexure. After it begins to bend, a lateral disruption soon takes place. A slender vertical prism is hence capable of supporting less pressure than the tension which it can bear. Thus a cube of English oak was crushed only by the load of 3860lb. but a bar of an inch square and 6 inches high gave way under the weight of 2572 lb. It would evidently have been still feebler if it had been longer. On the other hand, if the breadth of a column be considerable in pro- portion to its height, it will sustain a greater pressure than its cohesive power. Thus, though the cohesion of a rod of cast iron of the quarter of an inch square is only 300 lb., a cube of that dimensions will require 1440 lb. to crush it. In general, while the resisting mass preserves its erect form, the several sections are compressed and extended by additional weight, and their repellent particles are not only brought near- er, but multiplied. This repulsion is likewise increased by the lateral action arising from the confined ring of detrusion. The primary resistance becomes hence greatiy augmented in the progress of loading the pillar. - 3. Thransverse or Lateral Pressure. — Suppose the beam A B (in the annexed (figure) to have one end firmly implanted in a wall G H, and a vertical pres- sure applied at the other end. This beam, sinking under the load at B, may be conceived to turn on the lowest point at A as a fulcrum; consequently the particles of the vertical section AC will be forced into the oblique position A D, each of them being turned aside through a space proportional to its distance from A. The strain ex- erted at the end AC will therefore be the result of the aggre- gate dislocations of all the particles of the section. When the breadth and length of the beam remain the same, this accu- mulate strain must evidently be proportional to the area of the triangle C A D, and consequently to the square of the -depth A C. But when the breadth of the beam is taken likewise into account, the triangle of tension becomes converted into a wedge, and the strain hence follows the direct ratio of that breadth. Omitting the weight of the beam, and assuming its depth and breadth as constant, the tension of any particle at C may be considered as acting against the short arm A C of the rectangular beam C A B, and withstanding the load suspended at B. The weight thus resisted by the cohesion of the beam, is therefore inversely as the length A. B. Combining all these circumstances, we conclude, that the strength of a beam firmly inserted in a 103. % : - %*:::2:f- à ź 2% 22 ź à * % % % à %% z wall, or its power to resist a pressure at its remote extremity, is compounded of the direct ratios of its breadth, and of the square of its depth, and the inverse ratio of its length. Thus, a beam having the same length and breadth as another, but twice the depth, is four times stronger; and a beam of the same depth and breadth, and double the length, is only half so strong. Hence also, a beam, whose depth is triple its width, will sustain a load three times greater. For the same reason, a square prism will have its strength inversely as its length and the cube of its thickness. In general, the resistance of a beam of any form, but of a given length, to a cross strain, will be the same as if the whole power exerted were collected in the centre of gravity of each section. Thus, the strain of a trian- gular prism may be conceived as concentrated in a point at one-third of the distance of the perpendicular from the vertex to the base. Such a prism is therefore twice as strong set on its edge as when laid on its side. This simple investigation we owe to Galileo, and, though partly hypothetical, it is a near approximation to the truth. It is of essential service in im- proving the practice of carpentry, and sheds a clear light over the economy of nature in the structure of animals and vege- tables. Reeds and herbaceous plants derive their power of resisting the wind, from the subdivision of their length into moderate intervals by hard knots. But they acquire still greater strength from their tubular form; for the matter they contain, being thus removed to a greater distance from the fulcrum, exerts its cohesion with proportionally more effect, in with- standing any lateral impulsion. The bones of animals are likewise rendered stronger by their fistular structure, and their partition into short members connected by large compact joints. Hence, in the construction of fine mechanical and astronomical instruments, hollow brass cylinders, on account of their stiff- ness and lightness, are now preferred to solid pillars. If a bean be supported horizontally at both ends, and loaded in the middle, the pressure will be equally shared between the props; the effect is the same as if it were fixed at the middle, and each end pulled upwards by balf its load. The breaking weight is consequently double that required to tear a beam, of half the length, implanted in a wall. According to the principle of Galileo, therefore, this limit is inversely as the length of the beam, and directly as the breadth and the square of the depth. This result is confirmed by the numerous experiments which Buffon performed between the years 1758 and 1746. Thus, reducing all the quantities to English measures, an oaken beam, 4 inches Square and 10 feet long, broke under the weight of 4015 lb.; and another beam of the same wood, 8 inches square and 20 feet long, was broken by a load of 16,700 lb. The latter, being twice as thick, should have been eight times stronger with the same length; but the length being doubled, again reduced the excess to four times. - 4. In its Resistance to the Effort of Twisting or Torsion.—A cylindrical body suspended vertically, but having its upper end fixed, may be wrenched or turned round through any angle, by the exertion of some lateral force; and if its elasticity be not thus impaired, it will, after the deranging influence has ceased, return to its former position, and perform this retrocession in a certain time. Many substances may be considered as only bundles of parallel fibres, which by twisting exert an aug- mented longitudinal force. It will be more accurate, however, to view materials in general as composed of particles equally distributed through the mass. - STREPITOSUS, the name of a disease common to the in- habitants of some parts of the Alps, in which the face, neck, and arms are so distended with flatulencies as to sound, on being struck, like a dry bladder half distended with wind. STRETCHER, a narrow piece of plank placed athwart the bottom of a boat, for the rower to place his feet against, in order to communicate a greater effort to his oar. STRETCHING, is generally understood to imply the pro- gression of a ship under a great surface of sail, when close hauled. The difference between this phrase and standing, is apparently in the quantity of sail, which, in the latter, may be very moderate, but in stretching generally implies considerable, as, “We were standing in shore (under easy sail) when we dis- covered the enemy stretching to the southward,’ that is, under a crowd of sail. Il P 974 S T U S T R. DICTIONARY OF MECHANICAL SCIENCE. STRIKE, a measure of capacity, containing four pecks. Strike, among Seamen, is a word variously used. When a ship, in a fight, or on meeting with a ship of war, lets down or lowers her top-sails at least half-mast high, they say she strikes, meaning she yields, or submits, or pays respect, to the ship of war. Also, when a ship touches ground, in shoal water, they say she strikes. And when a top-mast is to be taken down, the word of command is, Strike the top-mast, &c. STRING, in Ship-building, the highest range of planks in a ship's ceiling, or that which lies between the gunwale and the upper edge of the upper-deck ports. STRIX, the Owl, in Natural History, a genus of birds of the order of Accipitres. Birds of this genus are rapacious. They are seldom seen by day, secluding themselves in the hollows of trees and buildings, and unable, from the particular structure of the eye, to endure the glare of sunshine. When they do appear in the day, they are pursued and persecuted by a variety of small birds, who combine in their expressions of ridicule and aversion, and soon oblige them to recur again to their retreat. During the season of general repose, they are active in quest of food, which in darkness they perceive with facility, and dis- turb the silence of night by loud and reiterated screams. Their usual prey consists of bats, mice, and small birds. Latham enumerates forty, and Gmelin fifty species. STROKE, a single sweep of the oars in rowing. Hence we say, “Row a long stroke;’ which is intended to move the vessel forward more steadily. • STROKESMAN, the person who rows the aftmost oar in a boat, and gives the stroke which the rest are to follow, so that all the oars may operate together. STRONTIAN, about the year 1737, a mineral was brought to Edinburgh by a dealer in fossils, from the lead mine of Strontian, in Argyleshire, where it is found imbedded in the ore, mixed with several other substances. It is sometimes transparent and colourless, but generally has a tinge of yellow or green. Its specific gravity varies from 3:4 to 3.726. texture is generally fibrous; and sometimes it is found crystal- lized in slender prismatic columns of various lengths. Strontian is found abundantly in different places of the world, and always combined with carbonic acid, or sulphuric acid. - STRONTIUM, the metallic basis of strontia. STROP, a piece of rope, spliced generally into a circular wreath, and used to surround the body of a block, so that the latter may be hung to any particular situation about the masts, yards, or rigging. Strops are also used occasionally to fasten upon any large rope for the purpose of hooking a tackle to the eye or double part of the strop, in order to extend or pull with redoubled effort upon the same rope; as in setting up the rigging, where one hook of the tackle is fixed in a strop applied to the particular shroud, and the other to its laniard. STRUTHIO, the Ostrich, in Natural History, a genus of birds of the order Gallinae. The black ostrich, is about eight feet long, and when erect measures about seven feet, and sometimes eight in height. One was exhibited in London in 1750, weigh- ing three hundred pounds. It is found in various parts of Africa, and about the Cape of Good Hope is particularly abun- dant. In the parts of Asia, near Africa, it is also met with. The ostrich subsists entirely on vegetable productions, but will swallow, occasionally, the most hard and even sharp-pointed substances, Iron, and various other metals, and even glass, have often been found in its stomach, and have unquestionably often proved fatal. It is related, upon respectable authority, that an ostrich will carry a man upon his back, and move with very considerable speed: some make the same remark with respect to two men. When unencumbered by any burden, its speed is truly extraordinary, and will exceed, in some instances, the ordinary rapidity of a horse. Dogs are sometimes em. ployed to hunt them down, followed by men on horseback, who contrive, by means of a long hooked staff, to lay hold of one of the legs of the bird, and thus bring it to the ground. They are applied to various purposes. Their feathers form an admirable ornament for the ladies; their skins are of sufficient thickness to be manufactured for the purpose of leather.—The galeated cassowary, is nearly equal in magnitude to the ostrich, but has a much shorter neck, and therefore is greatly inferior in height. On the top of its head is a species of helmet three inches high, Its and one thick at the base. Each wing, or what appears as such, is destitute of feathers, and has five bare shafts like those of the porcupine, and the body is covered with loose webbed feathers of a rusty black colour. It is never found beyond the tropical limits, and is no where abundant within them. It is unable to fly, but runs with great speed; and though it lives only on vegetables and fruits, which it is said to swallow un- broken, it is courageous, and even sometimes ferocious, and employs its legs to annoy its adversary by kicking.—The New Holland cassowary, is very similar to the above, but consider- ably longer. - STRY CHNIA, a newly-discovered vegetable alkali. M.M. Pelletier and Caventon, whilst analyzing the vomica nut, and the bean of St. Eustatia, have extracted from these two seeds a substance to which they owe their action on the animal economy. STUB, in Agriculture, a term signifying the root of a plant, with the top cut off. To Stub, is to grub up the roots or stumps of trees, shrubs, or brushwood, left in the ground after the tops are cut Off. STUBBLE, the strawy matter of the cut stalks, or stems of grain, remaining in the ground after reaping. In some parts of Essex, when mixed with much grass and weeds, it is burnt in the field. This tends to destroy the weeds, and the ashes become manure. - STUCCO, in Building, is a composition of white marble pulverized, and mixed with plaster or lime, the whole sifted and wrought up with water, to be used like common plaster. Of this composition are made statues, busts, basso relievos, and other architectural ornaments. A stucco for walls, &c. may be formed of the grout or putty made of good stone-lime, or the lime of cockle-shells, which is better, properly tempered and sufficiently beat, mixed with sharp grit-sand, in a propor- tion which depends on the strength of the lime: drift-sand is best for this purpose, and it will derive advantage from being dried on an iron plate or kiln, so as not to burn; for thus the mortar would be discoloured. When this is properly coln- pounded, it should be put up in small parcels against walls, or otherwise, to mellow, as the workmen term it; reduced again to a soft putty, or paste, and spread thin on the walls without any under-coat, and well trowelled. A succeeding coat should be laid on, before the first is quite dry, which will prevent joints of brick-work appearing through it. Much depends upon the workmen giving it sufficient labour, and trowelling it down. If this stucco, when dry, is laid over with boiling Jinseed oil, it will last a long time, and not be liable, when once hardened, to the accidents to which common stucco is liable. Liardet's, or, as it is commonly called, Adam's oil-cement, or stucco, is prepared in the following manner: For the first coat, take twenty-one pounds of fine whiting, or oyster-shells, or, any other sea-shells, calcined, or plaster of Paris, or any calcareous material calcined and pounded, or any absorbent material whatever, proper for the purpose; add white or red lead at pleasure, deducting from the other absorbent materials in proportion to the white or red lead added; to which put four quarts, beer-measure, of oil; and mix them together with a grinding-mill, or any levigating machine: and afterwards mix and beat up the same well with twenty-eight quarts, beer- measure, of any sand or gravel, or of both, mixed and sifted, or of marble or stone pounded, or of brick-dust, or of any kind of metallic or mineral powders, or of any solid material what- ever, fit for the purpose. For the second coat, take sixteen pounds and a half of superfine whiting, or oyster-shells, or any sea-shells calcined, &c. as for the first coat; add sixteen pounds and a half of white or red lead, to which put six quarts and a half of oil, wine-measure, and mix them together as before : afterwards mix and beat up the same well with thirty quarts, wine-measure, of fine sand or gravel sifted, or stone or marble pounded, or pyrites, or any kind of metallic or mineral powder, &c. This composition requires a greater proportion of sand, gravel, or other solids, according to the nature of the work, or the uses to which it is to be applied. If it be required to have the composition coloured, add to the above ingredients such a proportion of painter's colours as will be necessary to give the teint or colour required. In making the composition, the best linseed or hempseed, or other oils proper for the purpose, are S T U S (j B' 975 JDI CTIONARY OF MECHANICAL SCIENCE, to be used, boiled or raw, with drying ingredients, as the na- ture of the work, the season, or the climate, requires; and in some cases, bees-wax may be substituted in place of oil : all the absorbent and solid materials must be kiln-dried. If the composition is to be of any other colour than white, the lead may be omitted, by taking the full proportion of the other ab- sorbents; and also white or red lead may be substituted alone, instead of any other absorbent material. The first coat of this composition is to be laid on with a trowel, and floated to an even surface with a rule or darby, (i. e. a handle-float.). The second coat, after it is laid on with a trowel, when the other is nearly dry, should be worked down and smoothed with floats edged with horn, or any hard smooth substance that does not stain. It may be proper, previously to laying on the compo- sition, to moisten the surface on which it is to be ſaid, by a brush with the same sort of oil and ingredients which pass through the levigating machine, reduced to a more liquid state, in order to make the composition adhere the better. . This composition admits of being modelled or cast in moulds, in the same manner as plasterers or statuaries model or cast their stucco work. It also admits of being painted upon, and adorned with landscape, or ornamental, or figure-painting, as well as plain painting. For the invention of this stucco, Mr. Liardet obtained a patent in 1773 for fourteen years, the term of which was extended to eighteen years, in consequence of an act of parliament in 1776. For compositions very similar to the preceding, patents were granted to Dr. Wark in 1765, Mr. Emerton in 1771, and to Mr. Rawlinson in 1772. Dr. Shaw informs us in his Travels, (p. 286,) that the cement or mortar used in Barbary, which is apparently of the same consistence and composition with that of the ancients, is made in the following manner: They take two parts of wood-ashes, three of lime, and one of fine sand, which, after being well siſted and mixed together, they beat for three days and nights inces- santly with wooden mallets, sprinkling them alternately and at proper times with a little oil and water, till they become of a due consistence. This composition, he adds, is chiefly used in their arches, cisterns, and terraces ; but the pipes of their aqueducts are joined, by beating tow and lime, together with oil only, without any mixture of water. Both these composi- tions quickly assume the hardness of stone, and suffer no water to pervade them; and will, therefore, answer the purpose of Stucco. STUDDING-SAILs, certain sails, extended in moderate and steady breezes beyond the skirts of the principal sails, where they appear as wings to the yard-arms. The top-mast and top-gallant studding-sails are those which are set on the outside of the top-sails and top-gallant-sails. They are spread at the foot by booms, which slide out on the extremities of the lower and top-sail yards, and their heads or upper edges are attached to small yards, which are hoisted up to the top-sail and top-gallant yard-arms. The lower studding-sails, which are spread beyond the leeches of the main-sail, are fixed nearly in the same manner, only that the boom which extends the foot is hooked to the chain by means of a goose-neck, or else swings off with the sail to which it is suspended, being kept steady abaft by a rope called the guy. - STUFF, in Commerce, is a general name for all kinds of fabrics of gold, silver, silk, wool, hair, cotton, or thread, manu- factured on the loom ; of which number are velvets, brocades, mohair, taſſeties, cloth, serges, &c. The term is also used more particularly to denote slight woollen articles used princi- pally for linings and women’s apparel. - STUFF, any composition or melted mass, used to smear or daub the sides or bottom of a ship. The stuff which is chiefly used for the lower masts, is simply turpentine, resin, or varnish of pine; for the top-mast, tallow or butter; for the sides, tur- pentine, varnish of pine, tar and oil, or tar mixed with oil and red ochre; and for the bottom, a mixture of tallow, sulphur, and resin or tar, whale oil and broken glass, or any part of these ingredients; and this application is called giving a new coat of stuff to the masts, sides, &c. STUMI, in the Wine Trade, is a name for the unfermented juice of the grape, when it has been several times racked off, and separated from the sediment. The casks are for this pur- pose well fumigated with brimstone, in order to prevent fermentation, through which the juice would become wine. See MATCH ING. - STUMP, a name given to the root part of any solid body, particularly of trees, remaining after the rest are taken away. STUPA, a numbness occasioned by any bandage that stops the motion of the blood and nervous fluids, or by a decay in the nerves, as in paralytic strokes, &c. STURDY, a disease very prevalent among sheep, and which terminates fatally if not relieved in its early stages. STURGEON, a well-known, large, and fine-tasted fish, which spends part of its time in rivers and part in the sea. STURGEON. See Accipe NSER. - STYCHNOS, in Botany, a genus of the pentandria monogy- nia class and order. Natural order of Luridae apocineae, Jus- sieu. There are three species; we shall notice the S. nux vomica, poison nut. It is a native of the East Indies, and is common in almost every part of the coast of Coromandel, flow- ering during the cold season. The wood is hard and durable, and is used for many purposes by the natives. The root is used to cure intermitting fevers, and bites of venomous snakes. The seed of the fruit is the officinal nux vomica. STYLE, a word of various significations, originally deduced from a kind of bodkin, where with the ancients wrote on plates of lead, or on wax, &c. and which is still used to write on ivory leaves, and paper prepared for that purpose, &c. STYLE, in Chronology, denotes a particular manner of ac- counting time. Style is either old or new. The old style is that mode of computing time which is called the Julian, and is still followed in some states, that refuse to admit the reforma- tion of the calendar. The new style is that of Gregory XIII. which is followed by the Catholics, and by most Protestant kingdoms. STYLE, in Dialing, denotes the gnomon of a dial, raised on the plane of it, to project a shadow. STYLE, in Grammar, is a particular manner in which indi- viduals express their thoughts either in writing or speech, agreeably to the rules of syntax. Style has various other acceptations, as applied to music, oratory, poetry, philosophy, mathematics, &c. STYLET. See STILETTo. STYPTIC, a remedy that has the virtue of stopping blood, or of binding up the aperture of a wounded vessel. Many waters and powders are of this description; but in most, vitriol is the chief ingredient. STYRAX, the Storax Tree, a genus of plants belonging to the class of decandria, and to the order of monogynia, and in the natural system ranging under the 18th order, bicornes. SUBALTERN, an inferior officer, who discharges his post under the command of another, to whom his duty is to yield obedience. SUBERATS, salt formed with the suberic acid. SUBERIC ACID, an acid obtained from cork. t SUBJECT, in Legislation, a person under the dominion of a sovereign prince or state. Under the feudal system, those who held lands or tenure under the barons were deemed their sub- jects. In Anatomy, a body obtained for dissection is called a subject. In Logic, subject is that about which the thoughts and understanding are employed. SUBLIMATE. See CoRRosive SUBLIMATE. SUBLIMATION, in Chemistry, an operation by which vola- tile substances are collected and obtained. It is nearly allied to distillation, excepting that in the latter the fluid parts only of bodies are raised, whereas in sublimation the solid and dry are collected. SUBLIMITY, a term applicable to external objects, whe- ther works of nature or of art, as well as to powerful language, and, in short, to whatever is calculated to raise grand, terrible, and magnificent, ideas. It elevates the mind above ordinary scenes, and fills it with wonder and astonishment. SUBMULTIPLE, in Geometry, is a number or quantity con- tained in another, which being repeated a given number of times, becomes exactly equal to it. Thus 3 is a submultiple of 21. SUBNORMAL, in Geometry, is a line which determines the point, in the axis of a curve, where the normal or perpendicular, raised from the point of contact of a tangent to the curve, cuts the axis. 976. S U F S U G. DICTIONARY OF MECHANICAL SCIENCE. SUBORNATION, a secret or underhand preparing or in-I suffraGAN, a titular bishop, appointed to aid and assist structing a witness to give a false testimony. It is defined as an act that allures or disposes to perjury. - SUBPCENA, is a writ whereby all persons under the degree of peers are called into Chancery, in such case only where the common law ſails, and has made no provision; so as the party who in equity hath wrong, can have no other remedy by the rule and course of common law. It is therefore the commence- ment of a suit in equity. But the peers of the realm in such cases are called by the lord chancellor's or lord keeper's let- ters, giving notice of the suit intended against them,and requir- ing them to appear. There is also a subpoena ad testificandum, or a subpoena to give evidence for the summoning of witnesses, as well in Chancery as other courts. in the Exchequer, as well in the court of equity there, as in the office of pleas; which latter is a writ that does not require personal service, and is the commencement of a suit at com- mon law. - - SUBSCRIPTION, in Civil concerns, is the signature put at the bottom of a letter, writing, or instrument. SUBSCRIPTI on, in Commerce, is used for a share which par- ticular persons hold in a public stock, or a trading company. SUBSc RIPTION, in the Book Trade, is an engagement to take a given number of copies, on some stated terms. Subscription to the thirty-nine articles of religion, is a solemn declaration of the subscriber's assent to the doctrines and precepts they contain. SUBSIDY, in Law, signifies an aid or tax granted to the king by parliament, for the necessary occasions of the kingdom. SUBSTANCE, something that is capable of subsisting with- out dependence upon any created being, or any particular modes or accidents. There are but two kinds of substance known to exist, namely, matter and spirit. The former is dis- tinguished by its magnitude, extension, &c. and the latter by its consciousness, understanding, and volition. SUBSTANTIVE, in Grammar, a noun, or name, considered simply and in itself. SUBSTITUTE, a person appointed to officiate for another in case of absence, legal impediment, or agreement. SUBTANGENT of a CURve, in the higher Geometry, is the line which determines the intersection of the tangent with the axis; or, that determines the point wherein the tangent cuts the axis prolonged. - SUBTENSE, in Geometry, the same with the chord of an arch. * SUBTILE, in Physics, a thing remarkably small, fine, and delicate, such as the animal spirits, or the eſºluvia of odorous bodies, are supposed to be. The Cartesians suppose a very subtile matter to be the first element of their system. SU BTRACTION. See ARITH METIC. SUBULARIA, rough-leaved alysson, or awlworth, a genus of plants belonging to the class of ted radynamia, and order of siliculosa; and in the natural method ranking under the 39th order siliquosae. SUBURBS, buildings which stand near to the walls or spe- cific boundaries of a city or town, but are not included within their compass. SUCCINATS, salts formed with the succinic acid; which see, SUCCINIC ACID. Amber is a well-known, brown, trans- parent, and inflammable body, pretty hard, and susceptible of polish, found at some depth in the earth, and on the sea coast of several countries. SUCTION, in Physiology, the act of drawing into the mouth fluids, and other substances, by removing from the part where the operation is performed, the pressure of the external atmo- sphere, whilst on every other portion all its power remains unob- structed. Suction is little more than the formation of a par- tial vacuum, into which, when made by the mouth or other- wise, the fluid immediately flows. SUFFERANCE. Tenant at suſſerance, is he who holds over his term at first lawfully granted. A person is tenant at sufferance who continues after the estate is ended, and wrong- fully holds against another, &c. - SUFFOCATION, the termination of life by impeded respi- ration. This may be occasioned three ways, by hanging, drown- ing, or by carbonic acid gas. There is also a subpoena the bishop of the diocese. SUGAR, SACCHARUM, a very sweet, agreeable, saline juice, expressed from a kind of canes, or reeds, growing in great plenty in the East and West Indies. Pure sugar is perfectly transparent and colourless, when crystallized; but when gra- nular, of a pure gloss of white, soluble in water and alcohol, without smell, and with a simply sweet taste, having no other flavour. - It is a question not yet decided among botanists, &c. whether the ancients were acquainted with this cane, and whether they knew how to express the juice from the same : What we can gather from the arguments advanced on either side is, that if they knew the came and juice, they did not know the art of con- densing, hardening, and whitening it; and of consequence, they knew nothing of our sugar. Dr. William Douglas, in his Summary, &c. of the first plant- ing of our American settlements, printed at Boston in 1751, and reprinted at London in 1755, aſſirms, that sugar was not known among the ancient Greeks and Romans, who used only honey for sweetening. Paulus AEgineta, he says, a noted compiler of medical history, and one of the last Greek writers on the sub- ject, about anno 1625, is the first who expressly mentions sugar: it was at first called mel arundinaceum, i.e. reed or cane honey. He adds, that it came originally from China, by way of the East Indies and Arabia, into Europe, and was formerly used only in Syrups, conserves, and such Arabian medicinal compositions. Another question among the naturalists is, Whether the sugar-cane be originally of the West Indies, or whether it has been translated ratl, er from the East? The learned of these last ages have been much divided on the point; but F. Labat, a Dominican missionary, in a dissertation published in 1722, asserts that the Sugar-cane is as natural to America as India; and that the Spaniards and Portuguese first learned from the Orientals the art of expressing its juice, boiling it, and reducing it into sugar. SUGAR Cane, in Botany. See SAccH A Rum. - The root of this plant is jointed like those of the other sorts of canes and reeds, from which arise four, five, or more shoots, according to the age or strength of the root: these grow from eight or ten to twenty feet high, according to the richness of the ground ; but those of middling growth are the best. The canes are also jointed, and the length, as well as the size of the joints, depend upon the weather and the soil; at each joint are placed leaves, the lower part of which embraces the stalk or cane to the next joint above their insertion, before they expand. The first joint, which comes out either at the third, fourth, or fifth month, according to the season and soil, always keeps in its first place near the earth; out of this comes the second, and out of the second a third, &c. each week producing its joint, or very nearly, and a corresponding leaf likewise drying and fall- ing off nearly every week. A cane of thirty-two joints, which is fit to be cut, has from five to twenty-eight of them which have Post their leaves; the next five or six still have them, in a withered state, and ready to fall off; and the remaining joints, surrounded with green leaves, from the head, which is cut off after the leaf is withered. In a cane, whose length is from seven to nine feet, and which grows in a new, or a very moist and favourable soil, the number of useful joints is between forty and fifty, the first above the ground generally appearing at the end of three months, or, with frequent showers, a fort- night sooner; and many canes in such a soil are found rotten, or almost dried up, at the end of thirteen months: in a good soil, favourably exposed, well drained, and worked for a num- ber of years, canes not shorter than four feet and a half have thirty-eight or forty joints, the first joint appearing about the fourth, or middle of the third month, and many canes that have been cut in such a soil at the end of fourteen or fifteen months, being found rotten or dried: in a dry, but good soil, not manured, but well worked, and seconded by the season, the canes have been from three to four feet long, and have had from thirty to thirty- four joints; the first joint coming out at the end of four, or four months and a half; and canes of this kind have been found standing at the end of fifteen months, but very dry, and some- times a little changed: in a soil which is still drier, and more parched, canes which have been about two feet high, have had *~, S U G. S U G 977 DictionARY of MECHANICAL science. from twenty-four to twenty-eight joints, the first of which appears at the end of the fifth month, and many of these canes have been dried at the end of fifteen months. . r The time for cutting them is usually after twelve or fifteen months’ growth, but this varies according to the soil and the season. Those which are cut toward the end of the dry season, before the rains begin to fall, produce better sugar than those cut in the rainy seasons, when they are more replete with watery juice, and require a greater expense of fuel to boil it. In those plantations where the number of negroes is small, sugar is made in almost all seasons indifferently, and consequently the canes are planted when the planter is best prepared for his work, rather than at the most advantageous time. The system of cul- tivation among planters who are better supplied in respect of labourers, consists in planting a fourth or fifth of their land in October, November, and December ; in digging very deep trenches, for the greater nourishment of the root; in planting at great distances, for the benefit of a freer circulation of the air; and in cutting the canes in the four finest months, viz. February, March, April, and May, because the sugar is then the finest, the canes are cut with the least trouble, and supply (as is sup- posed) greater quantities of it. Those who adopt this method, cut about three-ſourths of their plantations, the remaining being made up of young canes, to be cut the following year, and for new plants. .' The manure generally used in sugar planting, is a compost formed of the coal and vegetable ashes drawn from the fires of the boiling and still houses; feculences discharged from the still house, mixed with rubbish of buildings, white lime, &c.; refuse, or field trash, i. e. the decayed leaves and stems of the canes, so called in contradistinction to cane trash used for fuel; dung, obtained from the horse and mule stables, and from cat- tle pens; and good mould, collected from gullies, or other waste places, and thrown into the cattle pens.—When the rat- toons or canes are ripe, as they ordinarily are in twelve or fif- teen months, or, as Mr. Cazaud apprehends, in eleven or twelve months, they are cut, and carried in bundles to the mill. SUGAR, Making of.--When the plants have attained their full growth, which, in the West Indies, is from twelve to fourteen months, the canes are cut short, tied up into bundles, and brought to the Crushing Mill, of which the following is a representation of those in common use. C Seºh Nº. \- EIFEIFT N | || ||||||}|ſº i. § \ º | } |: | * * * & ºn º Description.—A large block, a, is enclosed by a strong frame of timber; the upper surface of this block is hollowed out into the form of a basin, to receive the juice of the canes, which is expressed by the three vertical cylindrical rollers c, b, d, whose lower pivots work in sockets which are fixed in the blocka, and the upper in e. The upper and lower sockets, in which the pivots of the middle roller revolve, are fixed immoveably ; but the sockets of the other two are held between wedges, (as shewn in the engraving,) which are put in contrary directions, the Small end of one wedge being on the same side as the large end of the other; by which means the rollers may be either set far- ther from or nearer to each other. When it is required to set the outside rollers nearer to the middle roller, that wedge which is nearest the middle roller is to be driven out, and the other driven in ; and the contrary when they are wanted farther asun- der. These rollers are usually made of cast iron, having each a cog-wheel at the upper end on the same shaft, which causes | them all to turn together, when the power of a first mover is applied to the middle roller, by the shaft f. Behind the middle roller is a circular or concave piece of iron or wood, (not shewn in the above engraving) which is called the dumb returner, a name obviously given to the circum- stance of a man being always employed, previous to the inven- tion of this part of the apparatus, to perform the same office. In working the mill, a man takes a bundle of the canes, and applying them between the first and second rollers, (c and b) they are drawn in and préssed between them, but instead of proceeding in a right line, the ends of the cane strike against the concave surface of the dumb returner, which bends them round the middle roller, and causes them to enter berween the second and third rollers (b and d) which are placed somewhat nearer to one another than c and b, as the canes have already received great compression, and when they are thus returned through the front, they are received and carried off by another man. . The expressed juice runs down the rollers into the re- servoir, and is conveyed by the trough g to the boiling-house. It should be observed, that the reservoir on the top of the block a is only cut into channels round the outside of the rollers, to pre- vent the liquor running down and getting out betwen the wedges before mentioned. If a sugar mill be worked by the wind, the shaft f is connected with the vertical shaft of the mill. If by horses, the levers they work from are fixed to the shaft f, and the horse walk is either raised above ground higher than the trough, or the juice is conveyed by a pipe laid under the walk. Sugar-mills that are worked by a water wheel or steam-engine, have a bevelled wheel fixed upon the shaft f, and another upon the wheel or engine which turns it. Such is the pressure given to the canes in passing between the rollers of the mill, that they are not only squeezed completely dry, but are often reduced to powder. The refuse or macerated rind of the cane, which is called cane trash, serves for fuel to boil the liquor in the subsequent operations. The sugar is obtained by the following process:—The juice from the mill runs trom the receiver to the boiling house, along a wooden gutter lined with lead. In the boiling house it is received into one of the copper pans or caldrons, called clari- fiers. Of these there are generally three ; and their dimensions are determined by the power of supplying them with liquor: there are water mills that will grind with great facility, suffi- cient for thirty hogsheads of sugar in a week. Mcthods of quick boiling cannot be dispensed with on plantations thus for- tunately provided ; for otherwise the cane liquor would unfor- tunately become tainted before it could be exposed to the fire. The purest cane juice will not remain twenty minutes in the receiver without fermenting ; hence clarifiers are sometimes seen of a thousand gallons each : but on plantations that during crop time make from fifteen to twenty hogsheads a week, three clarifiers of three or four hundred gallons each are sufficient. The liquor, when clarified, may be drawn off at once with pans of this size, and there is leisure to cleanse the vessels every time they are used. Each clarifier is furnished with a syphon or cock, to draw off the liquor clear and free from the scum which is thrown up during the boiling. In order to assist in the separation of the gum, oil, and other vegetable principles which are intermixed in the expressed juice, and for the purpose of neutralizing the superabundant acid, a quantity of Bristol white lime, in powder, or in solution, is stirred into it, and in the proportions and manner of effecting this, according to the state of the liquor, consists one of the principal difficulties in sugar making. In this first process of clarification the liquor is not suffered to boil, but is allowed to do so when drawn off clear into the next pan, which is called the evaporating copper ; here the ebullition is continued (and the froth or scum removed by skimmers as it rises) until it becomes of such a consistence, as to be reduced in quantity very consi- derably, so that it may be contained in a much smaller copper, into which it is next ſadled. The liquor is now bright, and of the colour of Madeira wine. In this state, and of a certain consist- ency, it undergoes a farther evaporation in the vessel called the teach, until it is so far condensed as to he capable of granulat- ing when oool. The next operation is that of striking, which consists in ladling the thick liquor into the cooler. - The cooler (of which there are usually six, is a shallow wooden 11 Q 978 S U G S U G. DICTIONARY OF MECHANICAL SCIENCE. vessel about eleven inches deep, seven, feet in length, and from five to six feet wide, and is capable of holding a hogshead of sugar. Here the sugar grains, as it is called; i. e. it runs into a coarse irregular mass of imperfect crystals, Separating itself from the molasses. From the cooler it is taken to the curing-house. . . . . g g The curing house is a large airy building, provided with a capacious molasses cistern, the sides of which are sloped, and lined with terras or boards. A frame of massive joist work without boarding is placed over this cistern; and empty hogs- heads without headings are ranged on the joists of this frame. Eight or ten holes are bored in the bottoms of these hogsheads, and through each of the holes, the stalk of a plantain leaf is thrust, six or eight inches below the joists, and long enough to stand upright above , the top of the hogsheads. . Into these hogsheads the mass from the coolers is put, which is called potting; and the molasses drains through the spongy stalks of the plantain leaves, and drops into the cistern beneath; from whence it is occasionally taken for the making of rum by distil- lation. In the space of three weeks the sugar becomes tole- rably dry and fair; it is then said to be cured, and the process finished. Sugar thus obtained, is called the muscovado, and is the raw material whence the British sugar-bakers make their loaf or reſined lump sugar. - Several methods of clarifying have been adopted, and are still in use ; that, however, invented by Mr. Smith, and for which he oitained a patent, is entitled to a decided preference. The burning of the came trash had been found injurious to the molasses, but his steam apparatus, represented in the engray- ing, completely remedies this defect. - Reference to the Engraving.—a, is the finishing pan, or teach, b, the evaporating copper, c, the clarifier; this last is gently heated by the fluef from the distant fires, a and b are heated by, the same fire, through the medium of two separate steam boilers, d d and ee shews the depth of water they contain ; g is the fire- door, h the ashpit, i the feed-pipe for supplying water when ne- cessary, one of which is employed to each steam boiler. k k are safety valves for regulating the pressure of the steam, n the chimney. Cocks are fixed to each of the boilers for drawing off the water and the steam, which cannot be shewn in the sec- Iº9.2. 4 tional view. We shall now conclude by quoting some of the observations of the patentee on the subject. The bottom of the boilers is flat, and the spaces between them and the bottom of the sugar-pan forms the boiler, which need not exceed a foot in , depth for the largest apparatus. If the pans project beyond the boilers, it will be found advantageous; for the sides being cooler than the other parts, the fluid is prevented from boiling over, and the scum, as it forms, is thrown on the sides, and collected with greater facility. The steam being applied to every part of the bottom of the pan, cominunicates its heat to the liquor therein, and being thereby condensed, descends in drops of wa- ter to the bottom of the boiler, and is again raised into steam by the heat of the fire underneath, so that the operation conti- nually goes on, of generating and condensing in the same vessel, thus dispensing with force pumps and complicated feed pipes; however unequally the fire may act on the boiler, the effect on the bottom of the sugar pan is perfectly equalized by the intervening stratum of steam, an advantage peculiar to this apparatus. The steam boiler and sugar pan are made of thin copper, or iron; and to give sufficient strength to large sur- faces, they are united by riveted bolts at short and equal * distances, thus enabling thin metal to resist any required pressure of steam. SUGAR, Refining of, is the art of purifying sugar, and of giving a superior degree of whiteness and solidity. The excellence of muscovado sugars, or such as have not been refined by the planter, but are sent home in the most crude state, consists in their whiteness, dryness or freeness, cleanness and sharpness, or strength. The judicious refiner decides upon these several qualities by the eye, the touch, and the taste. The first opera- tion in the process of refining is that of clearing the pans; pre- viously to which they are charged, by throwing about six quarts of fresh bullock’s blood (called spice) into each pan, and filling it with lime-water to about half the height from the bot- tom to the part in which the brace is fixed ; and when these are well stirred together, the pan is filled to the brim with raw sugar. This mass, with a moderate fire, will, in about two hours, be brought to the verge of boiling heat : but it should not be allowed actually to boil; and in this time the earthy particles of the sugar, and other adventitious impurities, will be separated from it by the effect of the heat, and the cleansing quality of the spice, and thrown up to the surface. About two quarts of spice are added to each pan, within the first hour after the fires are lighted. The scum thus produced, which is usually from four to ten inches thick, is fit to be taken off, when the surface appears black and dry, and not greasy ; and it is gently removed with a broad skimmer into a portable tub, and conveyed into the scum-cistern. Flaving done this, the pan- man stirs together a ladleful of spice, (e. gr. about a quart,) and a quantity of lime water (e. gr. one or two gallons, as the case may require); and pours this mixture into each pan. When the sugar is again brought to a scalding heat, it throws up a . second scum, not so foul as the first, which is removed as before. He then adds a fresh quantity of spice, but less than the former, and repeats this operation till the sugar casts up a clean milky froth, which indicates that the impurity is wholly extracted. The liquor is also sometimes examined with a bright silver or metal spoon, that any remaining foulness may be dis- covered. In the making of double loaves, powder loaves, or very fine single loaves, it is usual to heighten the natural colour of the sugar by the addition of a little blue. For this purpose, when the pans are almost clear, the quantity of about six pennyweights troy of the finest indigo, finely powdered, and filtered through a piece of woollen or blanketing in a bason of fresh water, and well stirred together in a bason, is thrown into each pan. The sugar being once raised in the pan after this infusion, the grosser particles of the colour are taken off in | the last scum, and the remainder is incorporated with the sugar in the pan. The panman having brought the sugar to the cleanest state, prepares to skip it off, or to shift it from one vessel to another; this is done by means of a wooden guttef laid along the parts, and opening into the clarifying cistern. Over this cistern upon large iron bars is fixed an oblong basket, about sixteen inches deep, in which a large thick blanket is fastened : and through this blanket and basket the sugar liquid passes out of the gut- ter; and to the mass a quantity of syrup is usually added. Having measured the quantity of liquid in the cistern with a rod graduated by inches, the panman pumps back into the pans either the sixth or ninth part of the whole, as he is direct- ed by the supervisor or boiler; and the pans are all supplied together by means of a trough. When this is done, the fire is stirred up to a considerable degree of fierceness; and then com- mences a new operation, viz. evaporation. In this part of the process (the day’s work being divided into three fillings), the panman pumps into the pan one-ninth part of the quantity in the cistern, which in a few seconds begins to boil, and must be continued in a boiling state, but not with too intense a fire; and to prevent the sugar from boiling up to the surface of the pan, or from boiling over, he casts a small quantity (viz. a piece as large as a nutmeg or walnut, as the case may require) of butter or grease into the boiling liquor. Here it is to be observed that sugar should boil low in the pan, and yet not too flat like water, for by rising hollow from the bottom, the necessary evaporation is retarded, and the sugar is exposed to the action of the fire for a longer time than it ought to be. In a space of time from S U I S Ü P 979 DictionARY or MECHANICAL science. twelve to thirty minutes, the evaporation will have produced its effect, and the sugar acquired the requisite degree of viscous- ness. This state will be indicated by various circumstances; as the bubbles dragging heavily over the surface of the boiling mass, and by the clammy liquid falling in ropes from the proof- stick: but principally by that test which is called the proof. For this purpose the boiler draws the stick out of the boiling liquid with his right hand, and placing his left thumb upon the sugar, draws it across the stick, carrying away upon the end of his thumb as much of the sugar as will hang upon it; he then, by means of a candle placed in a black box called the proof- box, and by repeated trials (drawing the sugar to a thread be- tween his thumb and fore-finger) determines when the evapora- tion is complete; and when this is decided, the fire is smother- ed, and nearly quenched. The hot sugar liquor is then removed by means of basons out of the pans into coolers, two or three gallons being left in each pan, to prevent the bottom from being scorched; and the pans are again supplied with a quantity of liquor for the next evaporation. The liquor in the coolers is gently stirred, to prevent a crust from forming on its surface. The next operation in refining is conducted in that part of the ground-floor of a sugar house, which is denominated the fill- house, because all the upper floors of the house are to be filled from this ; and this operation consists in filling the moulds with the three skippings contained in the coolers. The moulds, in the form of inverted cones, previously prepared by soaking and washing them, and stopping their apertures with wet linen rags, are placed side by side, and in rows two or three deep ; their number is to suffice for the quantity of liquor in the coolers, which is estimated by the number of basons which were skip- ped off from the pans; and they are propped up by other moulds (commonly such as are broken) placed with the broad end downwards, in front of the outward rank, by way of abut- ment; these are called stayers. The sugar being previously stirred in the coolers in order thoroughly to mix, each skip- ping is ladled out of the coolers in succession, and not all at once, (unless the fillings are small, in loaves, and always in lumps,) into basons conveniently situated; and these are car- rie into the fill house, where as much of the sugar is poured into each mould as will fill about one third of its capacity; the same quantity is again poured into each ; and at the third time they are filled to the brim. The moulds being filled, the next operation, which is that of stirring the sugar in them, is called hauling, and is designed to prevent an adhesion to the mould, and to lay the grain of the mass even and regular through all its parts. In this business each man takes a tool made of wainscot, called a knife, and in size proportioned to that of the mould to be stirred ; with this tool, keeping his hand over the centre of the mould, he scrapes the sugar from its sides by successive strokes down- wards, carried all round; and when two revolutions are per- formed, the sugar is allowed to rest some minutes, until it has aequired some firmness. The moulds being stirred round three or four times, according to the direction of the boiler, are no more disturbed till they are pulled up.–The process already described relates to sugar once refined, called single loaves: double loaves are usually cleared with the whites of eggs instead of spice, (two hundred of which are necessary to each pan,) and with fresh water instead of lime water. With respect to the proof, one rule only can be laid down, viz. the sugar must be boiled higher as the moulds which contain it are enlarged. SUGAR of Roses, is white sugar clarified, and boiled into the consistence of rose water. When thus prepared, it is formed into small lozenges, and sometimes into grains about the size of peas, by keeping it stirred until cold and dry. It is thought serviceable to soften and allay acrimonies, &c. of the breast. SUGAR Spirit. This is a name given by distillers to a spirit made in England, Holland, and many other places, from the scum, washings, dross, and waste of a sugar-refining house. It is prepared in the same manner with that from malt and molas- ses, and is frequently used to adulterate brandy, rum, &c. SUGAR of LEAD. Acetate of lead. • SUICIDE, voluntary sclf-murder; the definitions of which, under all the circumstances that may occur, their variotis con- nexions and consequences, involve many curious, paradoxical, and perplexing questions. SUIT, in Law, is used in different senses, as, 1. Suit per- sonal. 2. Suit of court, or suit service, is an attendance that tenants owe to the court of their lord. 3. Suit covenant, is where the ancestor hath covenanted with another to sue to his court. 4. Suit custom, when a man and his ancestors have been seized, time out of mind, of his suit. 5. Suit real, or regal, when men come to the sheriff’s torn or leet. 6. Suit signifies the following one in chase, as fresh suit. 7. It signifies a petition made to the king or any great person. * SUKOTYRO, a genus of quadrupeds, of the order bruta generic character, horn on each side near the eyes. SULPHATES. Definite compounds of sulphuric acid with the salifiable bases. SULPHITES. Definite compounds of sulphurous acids with their bases. SULPHUR, is a well-known substance, sold in the form of a powder, or in solid pieces, when it is called brimstone. It is found in the neighbourhood of volcanoes : in the tract of land between Naples and the ancient Baiae, called Solfaterra, the sºpoking plains, the remnant of a half-extinguished volcano, it is found in great abundance. Sulphur is brought in largé quantities to this country from Mount Etna in Sicily, but is to be found in greater or less quantities near all volcanoes, of which the number throughout the world is very great. Sulphur is often found in coal mines, and indeed the common coal in our fires more or less contains this mineral. It is often found combined with iron, copper, and other metals, when it is called pyrites. - SULPHURETS, are combinations of alkalies, earths, or metals, with sulphur; hence a substance is said to be “sulphu- retted,” when it is combined with sulphur. SULPHURIC ACID, is generally procured by burning a mixture of sulphur and nitre in chambers lined with lead. Sulphuric acid is a liquid somewhat of an oily consistence, transparent and colourless as water, without any smell, and of a very strong acid taste. When applied to animal or vegetable substances, it very soon destroys their texture. —Sulphuric acid may be procured by the following process ; put into a glass retort two parts of sulphuric acid and one part of mercury, at d apply the heat of a lamp ; the mixture effer- vesces, and a gas issues from the beak of the retort, and may be received in glass jars filled with mercury, and standing in a mercurial trough. This gas is sulphuric acid. SUM, in Mathematics, signifies the quantity that arises from the addition of two or more magnitudes, numbers, or quantities together. - SUMACH. Common sumach (rhus coriaria) is a shrub that grows naturally in Syria, Palestine, Spain, and Portugal. In the two last it is cultivated with great care. Its shoots are cut down every year quite to the root, and after being dried, they are reduced to a powder by a mill, and thus prepared for the purpose of dyeing and tanning. SUMMONS, in Law, the citing or calling a person into any court, to answer a complaint, or to give evidence in cases that may require his testimony. SUN. See ASTRONOMY. SUNDAY, the first day of the week, and thus called by our idolatrous ancestors, because on this day the sun was worship- ped. . It is now more properly called the Lord's day, as comme- morating the resurrection of our Lord ; or Sabbath Day, being substituted under the gospel dispensation for the seventh day that was held sacred under the law. SUPERCARGO, a person employed by merchants to go a voyage, and oversee their cargo or lading, and dispose of it to the best advantage. SUPERFICIES, in Geometry, magnitude considered as hav- ing two dimensions, or an extension in length and breadth, but as being destitute of thickness or depth. SUPERFINE, in the Manufactories, a word used to express the superlative fineness of a stuff. The term applies both to the materials and texture. Among gold and silver wire draw- ers, that is said to be superfine which is reduced to a hair-like SI iº y ZC, * * SUPERLATIVE, in Grammar, an inflexion of an adjective, denoting the highest or lowest degree of the quality the word was intended to express. In English, the superlative is gene. * 980 S U R S U S DICTIONARY OF MECHANICAL scIENCE. rally formed by the addition of est, as wisest, poorest, blackest, &c. When the word has more than two syllables in its positive state, the superlative is expressed by the prefixing of most, as most honourable, most tremendous. - . SUPERNUMERARY, something over and above a fixed number. In several of the offices are supernumerary clerks, to be ready on extraordinary occasions. There are also super- numerary surveyors of the excise, to be ready to supply vacan- cies when they fall ; these have but half-pay. SUPERSED EAS, a writ that lies in a great many cases, and signifies, in general, a command to stay proceedings, on good cause shewn, which ought otherwise to proceed. By a supersedeas, the doing of a thing which might otherwise have been lawfully done, is prevented; or, a thing that has been done, is, notwith- standing it was done in a due course of law, thereby made void. A supersedeas is either expressed or implied ; , an express supersedeas is sometimes by writ, sometimes without writ; where it is by writ, some person to whom the writ is directed, is thereby commanded to forbear the doing something therein mentioned; or if the thing has been already done, to revoke, as that can be done, the act. A person can be superseded out of prison, when, by the practice of the court, the plaintiff has omitted to proceed in due time against him. . SUPPLEMENT of AN ARC, in Geometry, is the number of degrees that it wants of being an entire semicircle : , as comple- ment signifies what an arc wants of being a quadrant. In Literature, supplement is an appendage to a book, which sup- plies what was deficient in it. - SUPPLICAVIT, in Law, a writ issuing out of the court of King's Bench, or Chancery, for taking surety of the peace, when one is in danger of being hurt in his body by another. SUPPORTERS, in Heraldry, figures standing on the scroll, and placed by the side of the escutcheon, and seeming to sup- port or hold up the same. They are sometimes human figures, and at other times animals, and creatures of the imagination. SUPPURATION, in Surgery, denotes the process by which purulent matter is formed in cases of abscesses, ulcers, &c. SUPPURATIVES, are medicines that ripen and promote suppuration. - - SUPREMACY, in English polity, is the sovereignty of the king over the church as well as the state of which he is the established head. Among the Roman Catholics, this Supremacy in all ecclesiastical matters is lodged in the pope. SURA, the name of a liquor in the East Indies, made of the juice that is extracted from the cocoa-tree. It is, however, not held in very high estimation. SURCINGLE, a girdle with which the clergy of the church tie their cassocks. It is also a girth that comes over the sad- dle, and binds it firmly to the horse. - - SURD, in Arithmetic and Algebra, denotes any number or quantity that is incommensurable to unity, otherwise called an irrational number or quantity. SURETY, in Law, generally signifies the same with bail. SURETY of the Peace. A justice of the peace may, according to his discretion, bind all those to keep the peace, who in his presence shall make any affray, or shall threaten to kill or beat any person, or shall contend together in hot words; and all those who shall go about with unlawful weapons or attendance to the terror of the people; and all such person as shall be known by him to be common barrators; and all who shall be brought before him by a constable for a breach of the peace in the presence of such constable ; and all such persons, who hav- ing been before bound to keep the peace, shall be convicted of having forfeited their recognizance. Lamb. 77. SURETY of the good behaviour, includes the peace, and he that is bound to the good behaviour, is therein also bound to the peace ; and yet a man may be compelled to find securities for the good behaviour and the peace. SURF, the swell of the sea, which breaks upon the shore, or any rock lying near the surface, which renders such places dangerous. SURFEIT, an indisposition occasioned by eating or drink- ing to excess, or overcharging the stomach. It is usually attended with eruptions, and sometimes with fever SURGERY, is the art of curing or alleviating diseases by local and external applications, manual or instrumental. As a science, it may be defined, that department of maladies thus susceptible of alleviation or cure. SURNAME, a name added to the proper or baptismal name, to denominate the person of such a family. These hereditary names were first introduced by the Romans, on account of their league with the Sabines. . SURPLICE, the habit of the officiating clergy in the church of England. - - - SUR-REBUTTER, a second rebutter. SUR-REJOINDER. As a rejoinder is the defendant’s an- swer to the replication of the plaintiff, so a sur-rejoinder is the plaintiff's answer to the defendant's rejoinder. SURRENDER, a deed or instrument testifying that the par- ticular tenant of lands or tenements for life or years, does suffi- ciently consent and agree, that he who has the next or imme- diate remainder or reversion thereof, shall also have the present estate of the same in possession; and that he yields and gives up the same to him ; for every surrenderer ought forthwith to give possession of the things surrendered. - • SURROGATE, one who is substituted or appointed in the room of another; as the bishop or chancellor’s surrogate. SURSOLID, in Arithmetic, the fifth power of a number, or the fourth multiplication of any number considered as a root. SURVEY, in Law, the ascertaining of the boundaries and royalties of a manor; or estate in lands, and also of the tenure of the respective tenants, and the rent and value of the estate. SURVEYORS of The NAVY, two officers who sit at the navy board, being invested with the charge of building and repairing his majesty’s ships at the different dock-yards of the kingdom; for which purpose they are trained to the theory and practice of ship-building. - - SURVIVOR, in Law, signifies the longer liver of two joint tenants, or any two persons joined in the right of any thing. SURVIVORSHIP. Payments which are not to be made till some future period, are termed reversions, to distinguish them from immediate payments. These being founded on con- tingencies, form a most intricate subject of calculation. Survi- worship belongs only to those who survive other individuals, on the probable extent of whose lives the calculations are made, and the probable longevity of theirs who survive. SUS, the Hog, in Natural History, a genus of mammalia, of the order belluae. These animals are allied by their teeth to the carnivorous quadrupeds, and by their cloven feet to the ruminating ones. They feed almost indifferently upon animal and vegetable substances, devouring with a widity what is most nauseous and disgusting. They use their snout in dig- ging up the ground in quest of roots, are fond of rolling and wallowing in mud, and distinguished by extreme fecundity. There are six species, of which the following is the most im- portant.—The common hog. All the varieties of this animal originate in the wild boar, which is found in most of the temperate regions of Europe and Asia. It is smaller than the domesticated animal, and uniformly of a dark gray colour, ap- proaching to black. It is armed with formidable tusks, some- times ten inches, or even more, in length; those in the under jaw curving inwards, and capable, from their size, strength, and sharpness, of inflicting the most dreadful wounds. Before these animals attain their third year, they are gregarious, and, particularly when danger is at hand, they muster in numerous parties, and with great promptitude, at the signal of alarm. Uniting thus, they present so formidable an array, as speedily to disperse the enemy; few creatures, or mone, daring to com- mence an attack against such a combination of strength and valour as they exhibit. When the wild boar is complete in growth, he depends upon his solitary exertions for his protection, is seldom seen in society, ranging the forests alone; rarely commencing an attack, as his food consists almost solely of roots and vegetables, but repelling one with all the fierceness of courage, and all the resentment of retaliation.—The baby- roussa, is remarkable for the form and situation of the upper tusks, which are placed externally, and turn upwards in a curve towards the forehead. It abounds in the Indian islands, lives solely on vegetables, and rests itself, in sleep, by hooking its upper tusks round the branch of a tree. It can swim with rapidity, and is valued for food.—The Mexican hog, or pecari, is the only animal of the genus native of America, where it is S W E S W I 981 DICTION ARY OF MECHANICAL SCIENC E. gregarious, fierce, and dangerous, and is occasionally seen in herds of several hundreds. It feeds on fruits and roots, and also on serpents, lizards, and toads, and will attack and devour the rattlesnake, we are told, without the slightest injury. SUSPENSION, or Points of SUSPENsion, in Mechanics, are those points in the axis or beam of a balance, wherein the weights are applied, or from which they are suspended. Suspension of Arms, in War, a short truce agreed on by both armies, in order to bury their dead, wait for fresh Instructions, or the like. , - SUTTEE, the self-immolation of a widow on the funeral pile of her deceased husband. This horrid practice still prevails in many parts of India, even in those that are under the imme- diate government of the English. SWAB, a sort of mop, formed of a large bunch of old rope- yarns, and used to clean the decks and cabins of a ship. Hand- Swab, a smaller kind, used for wiping dry the stern-sheets of a boat, washing of plates and dishes, &c. SWABBER, a man appointed to use the swabs in drying up the decks. He is sometimes called ship's swabber, but more commonly captain's swabber. - - SWALLOW. See Hi RUNDo. SWAN, in Ornithology, a species of the anas or duck kind, of which there are two sorts, the wild and the tame. The tame swan is the largest of the English birds. SWARD, in Agriculture, the green or grassy surface of the round. g SWARD-CUTTER, a kind of plough invented by Mr. Sandi- land, for the purpose of preparing old grass grounds for future purposes. This instrument is described at large in the sixth volume of the Bath papers. - SWARM. See Bees. - SWATH, a term denoting the ridge or line of newly mown grass or corn, as laid by the mowers. Swath-Bulk, is the ridge of a stubble laid between two swaths in mowing. SWEARING, an offence punishable by several statutes; thus, stat. 6 and 7 Will. III. cap. 11. ordains, that if any per- son shall profanely swear, if he is a labourer, servant, or com- mon soldier, he shall forfeit Is... to the poor, for the first offence, 2s. for the second, &c.; and any person not a servant, &c. forfeit 2s. for the first offence, 4s. for the second, 6s. for the third, &c. to be levied by distress of goods. - SWEAT, a sensible moisture issuing through the pores of men or animals, occasioned by too much heat, exercise, or weak- ness, or through the action of medicines called sudorifics. SWEATH. See SWATH. we first settled among them, had a great many houses to sweat in, it being their general remedy for diseases, of whatever kind; but at present they are less used among them. The cave, or sweating house, is usually eight feet in diameter, and four feet high, the roof being supported by sticks or boards. They usually dig 1 bese caves in the side of a hill, and as near as can be to some river or pond. The entrance into the cave is small, and when any person is sweating in it, the door is covered with a blanket or skin. Near the cave they usually make a large fire, and heat in this a quantity of stones, perhaps five hundred weight; these they roll up into the cave, and pile up in a heap in the middle. When this is done, the Indians go in naked, as many as please, and sit round the heap of stones; and as soon as they begin to grow faint, which is usually in a quarter of an hour, they come out and plunge themselves all over in the water, remaining in it a minute or two ; and repeat- ing this a second time, they dress themselves, and go about their business. This has been for many ages used among them with Success, in cases of colds, surfeits, sciaticas, and pains fixed in their limbs; and the English have often used the same | means, and found relief by it. It is practised equally at all times of the year, and the Indians do it not only in sickness, but by way of refreshment after long journeys, and other fa- tigues, and to strengthen themselves for any expeditions. SWEATING-Sickness, a malignant disease which prevailed in England about the conclusion of the fifteenth and beginning of the sixteenth centuries, through which many thousands died. swººnbokglass, a sect of mystics, so called from bear each a considerable part. - man, it may be considered as highly useful, since it contributes the ingenious and learned, though eccentric, Emanuel Sweden- borg, a Swedish nobleman. SWEDISH TURNIP, the name of a hard sort of turnip originally imported from Sweden, of which there are two sorts, the yellow and the white, but the former is deemed the more valuable. An instrument called the Swedish Turnip Cutter, for slicing these roots with great expedition, may be had of every farming-implement maker. SWEEPERS, persons appointed (sometimes by way of punishment) to sweep the decks occasionally with brooms. Captain Sweeper, a man who has command over the preceding gang. Sweeper of the Sky, a name given by sailors to the N. W. winds of America. SWEEPING, the act of dragging the bight, or loose part of a small rope, along the surface of the ground, in a harbour or road, in order to hook and recover some anchor, wreck, or other material, sunk at the bottom. It is performed by fastening the two ends of the rope to the sides of two boats, abreast of each other, at some distance. To the middle of the rope is sus- pended a weight, to sink it to the ground, so that as the boats advance by rowing ahead, the rope drags along the bottom, in order to hook any anchor, &c. for which they are searching SWEEPS, large oars used on board ships of war in a calm, either to assist the rudder in turning them round, or to increase the ship's velocity in a chase. Sweep of the Tiller, the circular frame on which the tiller traverses, in large ships. SWEETBRIAR, a shrubby plant of the briar kind, frequent- ly cultivated in gardens for its fragrant and delightful smell. SWELL, generally denotes a heavy and continued agitation of the waves, rolling in any particular direction. It is, how- ever, more particularly applied to the fluctuating motion of the sea which remains after a storm, as also to that which breaks on the sea-shore, &c. SWIFTER, a rope used to confine the bars of the capstan in their sockets, while the men are turning it round ; for which purpose it is passed through holes in the extremities of the bars, so as to attach them firmly to each other like the felloes of a wheel, which operation is called swifting. See the article CAPSTAN. Sw IFTER, is also a strong rope, sometimes used to encircle a boat lengthwise, as well to strengthen as to defend her sides from the impression of other boats which may run against her. It is usually fixed about nine inches below the boat's gunwale or upper edge. Swifters, are likewise two shrouds, fixed on the starboard and Harboard sides of the lower masts, above ałł the other shrouds, as an additional security to the masts, and are never confined, like them, to the catharpings. SWEATINGHOUSE. The natives of North America, when | SWIMMING, the act of sustaining the body in water, and of moving in it; in which action the air-bladder and fins of fishes So far as this exercise applies to to the development of the muscular powers, to the increase of strength, and the preservation of health. If we consider swim- ming in regard to cleanliness, it possesses the advantages of a cold bath, so frequently recommended as a most useful remedy to cleanse, fortify, and strengthen the body ;—if we regard it as a means of preservation, we must acknowledge, that of all exercises there are none which give to us more confidence and more courage, under perilous circumstances: added to which is the high gratification we may procure to ourselves, from being the instrument of snatching a fellow creature, perhaps a friend, from a watery grave. It must not, however, be forgotten, that we can but have little pleasure and no safety in the water, as indifferent swimmers. Experience proves to us that more fatal accidents happen to those who swim imperfectly, than to such as cannot swim at all, the latter having no temptation to expose themselves to danger. With many who are unacquainted with the art, and feel an instinctive repugnance to it, an opinion prevails that the danger is too great to be encountered, and the difficulties too formid- able to be surmounted. These notions are entirely founded on mistake. In cases where the corporeal qualifications may not be great for swimming, yet if a person persevere in his efforts, he will become an excellent swimmer in a very short time, even with a feeble constitution or bodily defects. It is also an error to believe, that grown-up men cannot learn to Swim : 11 R 982 S W I S W I DICTIONARY OF MECHANICAL SCIENCE. experience daily teaches us the contrary; and the great num- ber of soldiers and private individuals who are taught swimming in the different European establishments, proves clearly to us that a person can learn at any period of life, even so as to be- come very expert in the art. All swimmers being of opinion, that it is only the position of the body and the regular move- ments of the limbs which give them the power of swimming for a length of time and without much fatigue, it is evident that children may be taught the elementary principles of matation without having recourse to water, or to a number of instruments, which only augment the difficulty. The summer being very short, and often cold, in northern climates, and even in more temperate ones, young persons have not the same facility of bathing every day, and at any hour, as those who live in more southern countries; added to which, the water of the rivers in these countries is always cold, which prevents their remaining in the bath as long as they could wish. This circumstance is a great obstacle to the progress which they might make in swimming, and frequently disgusts them with this exercise. As to the precautions, we request the instruc- tors not to be too rough with their pupils, and, above all, never to force them to leap into the water, without their being able to swim, nor to permit them to bathe immediately after dinner, nor to go into the water when they are very hot; on the other hand, they must not wait until entirely cold. After violent ex- ercises it is wrong to bathe, but persons may wash themselves, at the same time rubbing their joints with much more force. We also recommend friction before swimming, as the surest way to be preserved from the cramp and giddiness. Friction after the bath, by making the blood circulate more freely, dis- tributes it over every part of the body, which soon gets be- numbed in cold water, while a little hard rubbing creates an agreeable glow over the whole frame. Besides these advan- tages, by frequent friction, the joints, muscles, and articulations, acquire a great deal of strength and elasticity. The swimming apparatus necessary for teaching, consists of a girdle of a hand's breadth, of a rope from five to six fathoms in length, and of a pole eight feet long, with large drawers and jacket of linen, fastened together by buttons. . The depth of the water in the place chosen for swimming should, if possi- ble, be not less than eight feet, and selected in the clearest and calmest water possible. Elementary Principles. First Lesson in the Water.—The swim- ming girdle is placed round the pupil’s breast in such a manner, that its upper edge touches the pap of the breast, (see the figure.) The pupil is then conducted to the water, and recommended to ge gently into it. As soon as the pupil is in the water, in order to inspire him with confidence, the teacher winds the end of the rope, which he holds in his hand, round the pole, and leaning the pole on the rail, he swings the pupil into the water, in such a way, that the latter appears to repose on its surface. The pupil is not placed in a perfectly horizontal position, the head is plunged up to the mouth, the arms are stiffly stretched for- wards, so that the palms of the hands touch each other; the legs are also stiffly stretched out, and the heels are kept to- gether, but the toes are turned to the outside and contracted, as in the annexed figure, this is called ranging. In this posi- tion the pupil must remain for some time, till he feels it be- comes easy to him. When this is well known, the pupil pro- ceeds to the movements. That of the feet is taught first, during which the arms are to remain immoveably stretched out. The motion of the legs is divided into three parts: first, they are slowly drawn under the body, and at the same time the knees separate to the greatest possible distance; the spine is bent downwards, and the toe kept outwards. Secondly, the legs are stiffly stretched out with a moderate degree of quickness, while the heels are separated, and the legs describe the wid- est possible angle, the toes contracted and kept outwards. Thirdly, the legs, with the knees held stiffly, are quickly brought together, and thus the original position is again obtained. The main advantage of swimming lies in this third part of the motion. The pupil is now loosened from the pole, but remains attached to the rope. The teacher then takes the loose end of the rope, and causes him to take a running leap into the water, to rise without help to the surface, and thus to commence swimming alone, During the leap, the legs are to be kept together, and the arms close to the body. Above all, the pupil should be enjoined, when he rises to the surface, not to open his mouth immediately, but previously to repel the water from his nose to prevent head-ache. When necessity compels us to jump from a certain height into shallow water, in a place with which we are not acquainted, or in a muddy river, it is of great import- ance to place the feet or hands foremost, observing to extend the diagonal line, which the body is to describe as much as possible. With some practice in this exercise, one may jump from the height of twenty feet, in water only five feet deep, without hurting himself. In a regular swimming school, to im- prove a great number of scholars in a very short time, one ought to fix in the centre of it, (in a large barge for instance,) a mast, upon the top of which ten or more ropes could be fixed. The pupil tied at the end describes a large circle, swimming round the barge, and can stop when he likes. This is one of the most amusing and improving exercises in the art. Diving. The exercise of diving must begin by remaining under water without motion. The most pleasant manner for the diver is, to let himself sink gently into the water, by means of a pole or rope. The breath must be drawn in slowly, and expelled by degrees, when the heart begins to beat very strongly. If the pupil has practised himself in this for some time, he may then begin to swim under water and to dive to the bottom. In swimming under water, he may either move in the usual way, or keep his hands stretched before him, which will enable him to cut the water more easily, and greatly relieve the breast. If he wishes to dive to the bottom, he must turn the palms of the hands upwards, striking with them repeatedly and rapidly, whilst the feet are reposing; and when he has obtained a per- pendicular position, he should stretch out his hands like feel- ers, and make the usual movement with his feet; then he will descend with great rapidity to the bottom. It is well to accus- tom the eyes to open themselves under the water, at least in those beds of water which admit the light, as it will enable us to ascertain the depth of the water we are in. Saving from Danger.—It is necessary for a swimmer to know how to act in rescuing a drowning person without himself be- coming the victim, as so often happens ; we therefore lay down the following rules:—The swimmer must avoid approaching the drowning person in front, in order that he may not be grasped by him; for wherever a drowning person seizes, he holds with convulsive force, and it is no easy matter to get disentangled from his grasp ; therefore he ought to seize him from behind, and let him loose immediately the other turns towards him ; his best way is, either to impel him before to the shore, or to draw him behind; if the space to be passed be too great, he should seize him by the foot and drag him, turning him on his back. If the drowning person has seized him, there is no other re- source for the swimmer than to drop at once to the bottom of . the water, and there to wrestle with his antagonist; the drown- ing man endeavours, by a kind of instinct, to regain the surface, and when drawn down to the bottom, he usually quits his prey, *º- S Y P S Y R. 983 DICTIONARY OF MECHANICAL SCIENCE. particularly if the diver attacks him there with all his power. For two swimmers, the labour is easier, because they can mu- tually relieve each other. º SWINE. See SUS. º SWIVEL, a small piece of artillery, carrying a shot of half a pound, and fixed in a socket on the top of a ship's side, stern, or bow, and also in the tops; the trutinions of this piece are contained in a sort of iron crotch, whose lower end terminates in a cylindrical pivot resting in the socket, so as to support the weight of the cannon. By means of this swivel (which gives name to the piece of artillery) and an iron handie on its casca- bel, the gun may be directed by hand to any object. Swivel is also a strong link of iron used in mooring-chains, &c. which permits the bridles to be turned repeatedly round, as occasion requires. SWORD. A weapon used either in cutting or thrusting ; the usual weapon of fights hand to hand. It also signifies figuratively, destruction by war; as, fire and sword. SYCAMORE, (Acer Pseudoplatanus,) the Plane Tree of Scotland, and Ficus Sycamorus, the Egyptian Fig-tree; both grow to a large size. The wood of the former is soft, white, and chiefly valued by turners. - SYLLABUB, a kind of compound drink, chiefly in demand during summer. It is ordinarily made of white wine and sugar, into which some new milk is thrown by a syringe. The ingre- dients, however, vary in different hands, as also the proportions. of the articles used. SYLLOGISM, in Logic, an argument or term of reasoning, consisting of three propositions; the two first of which are called premises, and the last the conclusion: as, Every creature possessed of reason and liberty, is accountable for his actions. Man is a creature possessed of reason and liberty; therefore man is accountable for his actions. * SYMBOL, a sign or representation of any moral subject by the images or properties of things natural. Thus, courage finds its symbol in the lion, parental affection in the pelican, &c. Among Christians, bread and wine are symbols of the body and blood of Christ. * SYMPATHY, an agreement of affections and inclinations, or a conformity of humours, temperaments, and natural quali- ties, which makes two persons pleased and delighted with each other. The various opinions that have been entertained re- Specting the power of sympathy, have led to many curious and romantic speculations. - SYMPHONY, in Music, properly denotes a consonance or concert of several sounds agreeable to the ear, whether vocal or instrumental, called also harmony. SYMPTOM, in Medicine, denotes any change in the body or its functions, (perceptible either to an observer, or, to the patient himself,) which indicates disease. SYNAGOGUE, literally imports an assembly or congrega- tion; but it is now restricted to a particular assembly of the Jews, met to perform the offices of their religious worship. SYNCHRONISM, the happening of several things or events together, at or in the same time. SYNCOPE, in Physiology, fainting. SYNECDOCHE, in Rhetoric, a figure, in which the whole of a thing is put for a part of it only, or a part for a whole. This figure is of very considerable latitude ; and is used, 1st, when the genus is put for the species; 2dly, when the species is put for the genus; 3dly, when the essential whole is put for one of its parts; 4thly, when the matter or form is put for the whole . 5thly, the whole for a part; or lastly, the part for the Wn Ole. SYNOD, in church history, is a council or meeting of eccle- siastics, to consult on matters of a religious nature. *QP SYNTAX, in Grammar, the proper construction or due dis- position of the words of a language into sentences. SYNTHESIS, in Logic, a method of pursuing truth by reasons drawn from pre-established principles, or propositions already proved, and thus we reach the conclusion. SYPHON, On the more extensive Employment of the. The Syphon, one of the most simple but at the same time interesting of hydraulic instruments, may be very considerably extended. We shall at present content ourselves with pointing out the ad- proceeding by a regular chain, until vantage with which it may be applied to the conveyance of water to a distance over eminences, from a spring, well, &c. properly situated for the purpose. The usual methods of con- veying water in such situations are either by cutting away the eminence to lay a pipe at a sufficient depth to obtain a fall, or by raising the water, by means of a pump, to a reservoir, and conveying it thence by a pipe to the situation required: both these methods we consider objectionable; the former, because of the great labour and expense attending the execution, be- sides the difficulty of getting to the pipe in case of a leak or stoppage; and the latter, on account of the original expense, the continual labour of pumping, liability of the pump to get out of repair, &c. The syphon is liable to few or none of these objections; and the reason it has been so little employed is probably the difficulty or the expense of exhausting the air from out of the syphons on a large scale. To obviate this, may be adopted the following simple and easy method of setting any syphon to work, how- ever large its dimensions, provided the perpendicular height of the shorter leg is not greater than the column of water capa- ble of being raised by the pressure of the atmosphere. This method is not only simple, and easy to be repeated when neces- sary, but attended with so trifling an expense as must remove any objection on that score. - | s: § §|Él; s ^ MV . § §§s jº, a a a represents the surface of the ground , b c d e, a well, the depth of which we will suppose to be seven yards, and the depth of water one yard; f the situation where the water is wanted, the distance of which from the well is immaterial. AA A, the syphon ; at the extremity of the shorter leg B, which is immersed in the water, is a valve opening upwards, and at the other extremity is a cock, which may either be a common one, or one with a ball, &c, according to circumstances; at the crown of the syphon, a pipe C is soldered to the highest part of the bend, for the purpose of filling the syphon with water, and which must be done gradually, to admit the air to escape as the water descends. When the syphon is quite filled with the wa- ter, the top of the pipe C must be made perfectly air-tight, by means of a screw-cap, with a collar of leather, or, if on a large scale, by means of a flange, with screw bolts and nuts, &c. When this is done, turn the cock at f, and the water will com- mence and continue a rapid stream, as long as any remains in the well. Great care must of course be taken that the pipe composing the syphon is good, and perfectly air-tight. - SYRINGE, an instrument so constructed as to imbibe a quantity of any fluid, and to squirt or expel the same with vio- lence. The uses to which the syringe has of late been applied, have rendered it so important, that for one invented by Mr., Read a patent has been obtained, and its vast utility renders it worthy of a particular description. In cases of swallowing poison, it has been so repeatedly and successfully tried, that no doubt can remain as to its intrinsic value. The apparatus consists of the pump, now generally known by the name of the “Stomach Pump,” the oesophagus tube, three leathern tubes, and three ivory pipes, (which last, with the third leathern tube, is used only for enemas,) and a brass socket. The cylinder of the pump or syringe, (made in brass and in silver,) is about seven inches in length, and one inch in diameter, contracted at its apex into a small opening for receiving the extremity of an elastic tube, which is passed into the stomach. Within this opening is a chamber containing a spherical valve, which, by rising into the upper part of the chamber, where a vacuum is formed by elevating the piston, admits the fluid to pass freely into the syringe, but as soon as the piston is depressed, the contents of the syringe press the valve close upon the aperture, 984 S Y. R. S Y R. DICTIONARY OF MECHANICAL SCIENCE. and prevent its escape through the opening by which it was received. To give exit to the contents of the syringe, a side brafich is constructed, furnished with a välved chamber, similar to the one above described, but so placed as to act in direct opposition to it, so that when the syringe has been filled from the extretnity, and pressure is made by depressing the piston, the fluid closes the lower valve, and opens the lateral one, and engraving. Figure A represents the operation of in- jecting fluids into the stomach, to dilute the poison pre- vious to its extraction. This is effected in the following manner:—Screw the two first lengths of the leathern tube to the lateral branch of the syringe, and next the detached socket to the extremity of the former. The oesophagus tube is now to be passed through the mouth into the stomach, which being done, insert the brass joint at its extremity, into the socket at the end of the leathern tubes. The fluid to be injected, being put into a basin or other shallow vessel, the end of the syringe is immersed in it, and the piston being put into action, any quantity may be thrown into the stomach that shall be desired. -. - Emptying the Stomach.-A sufficient quantity of fluid having been injected into the stomach by the above pro- cess, the enema tube is to be withdrawn from the oeso- phagus tube, (without removing the former from the syringe, or the latter from the stomach,) and the joint of the oesophagus tube inserted into the extremity of the syringe; let an assistant now hold a vessel to the end of the enema tube, and by working the piston, the contents of the stomach may speedily be pumped into it, as shewn in figure B of the drawing. By thus trans- ferring the end of the oesophagus tube from one situa- tion to the other, the two processes of washing and emptying the stomach, may be repeated as often as is judged necessary by the operator. Thus it is seen that the syringe is furnished with two valvular apertures, through one of which the contents of the stomach pass into the cylinder, and are then immediately forced through the other into the receiving vessel. This double operation is effected by repeated strokes of the piston, which slides so easily, that an infant may use it. The mander in which the syringe is held in the two separate operations, is very important. In the first, as is seen in the engraving, a perpendicular position is the most eligible; but in the second, the syringe must be held in an inclined position, at about an angle of 45°, with the lateral tube upwards. These positions preserve the valves upon their proper bearings, with- out which the instrument cannot act perfectly. - A New Method of Operating with Read's Patent Syringe.—An improved mode of removing poison from the stomach with this instrument was first adopted in St. Thomas's Hospital, and has since been performed successfully in a variety of cases, as represented in the following sketch. a, a guard, to be intro- duced between the teeth, for-protecting the oesophagus tube from injury. 2-/T ( ſ ſ /N) a - r º GECEO rºWW NIT/x, $º: E-ºº-ººrºº $ºs- ==3 º:” $º º *. !/ Sz º £7. - This is by far the quickest, easiest, and most simple mode of operating that has hitherto been devised, requiring no shifting of l the apparatus, nor interruptions of the operation. It consists consequently escapes through the latter aperture. To facilitate the operation of the instrument, a small pipe communicates with the upper extremity of the syringe, which gives free ingress and egress to the atmosphere during the action of the piston, a circumstance essentially necessary in causing the instrument to work easily and perfectly. The operation of evacuating poison from the stomach, is represented in the annexed simply in filling the stomach, (according to the method of fig. A, in the preceding engraving,) until surcharged, or until it begins to react upon its contents, when the fluid regurgitates by the mouth. The pumping being now continued, the contents of the stomach are washed up, and forced, by the power of the pump, through the oesophagus (by the side of the tube) into a vessel held under the chin to receive it. The operation may be con- tinued as long as the surgeon thinks proper; or until the fluid returns unchanged, which indicates the thoroughly cleansed state of the stomach. The operator may occasionally suspend the action for an instant, if necessary, to allow the patient to inspire. By this means the fluid may be injected in the quantity of three quarts a minute.—But it is not merely to the extracting of poisons from the stomach that the use of the patent syringe is confined, as may be gathered from the following particulars, Injecting the Bladder.—In cases of retention of urine, it fre- quently happens, that in consequence of haemorrhage and other causes, the catheter becomes so obstructed that the bladder cannot be emptied. It was suggested to Mr. Scott by Dr. Cloquet, a celebrated surgeon of Paris, to effect this purpose by fixing a pump to the catheter. The patent syringe performs this operation with extreme facility, and has been honoured with the entire approbation of Dr. Cloquet. For injecting the bladder, which is an operation every day becoming more fre- quent, it is of course equally eligible. For these purposes, Mr. Read has constructed elastic gum catheters, to be fixed to the extremity of the enema tube: see e in the following en- graving. g t As an apparatus for conveying nourishment into the stomach | of persons afflicted with stricture of the oesophagus, and stimu- j Jating liquids in cases of suspended animation, the patent syringe is found to possess obvious advantages. - Cupping and Drawing the Breasts.-This pump is also capable of being adjusted to cupping-glasses, by which any degree of S Y R. S Y R. DICTIONARY OF MECHANICAL SCIENCE. 985 exhaustion can be made, that the operator desires; and in the same manner it may be rendered a very effectual instrument for drawing the breasts of puerperal females. Mr. Read has had glasses made for these uses, which may be obtained with the rest of the apparatus: see f, g, in the succeeding engraving. Tobacco Fumigation and - • * Enema Injection.--Tobac- co Fumigation. Figure C in the first Plate, repre- sents the syringe with a canister, for the purpose of injecting tobacco fumes into the intestines. It is used in the following manner: Unscrew the cap of the canister, and take out the perforated plum- a ger; put in the tobacco º (half an ounce, or an - - ounce) and replace the plunger lightly upon it; then put on the cap, and screw it to the end of the syringe; hold a lighted candle close under the bottom of the canister, and a stroke or two of the piston of the syringe will light the tobacco. The enema tubes being now fixed to the side branch, and the pipe introduced into the rectum, the tobacco-smoke is forced into the intestines as long as the syringe is worked in the usual Iſlalºlº Clſ. Operation of administering Enemas.-We have lastly to speak of this syringe as an instrument for administering enemas, which was the original intention for which it was constructed, and in this point of view it is of the highest importance. On this subject Mr. Read has been favoured with the following remarks from the pen of Mr. Scott, and we gladly avail our- selves of his permission to insert them. “The objects of administering enemas are considered to be of three kinds: 1st, For softening and diluting retained faeces; 2ndly, For stimulating the bowels, and thus provoking evacua- tions; and, 3rdly, For producing mechanical distension. It must be obvious to every medical practitioner, how very in- adequate the old apparatus of the pipe and bladder is to the completion of these objects; and thence it is that various in- struments have been at different times devised, to remedy the deficiency; but ingenuity had been exercised in vain, and the profession were still in need of an instrument to effect these valuable ends, until the patent syringe supplied the desired means. It had hitherto been the custom of surgeons, in ad- ministering enemas, to throw up three-quarters of a pint, or a pint, of fluid ; and a clyster, even in the severest cases, rarely exceeded the latter quantity. Now, by an attention to the anatomical structure of the lower intestines, it must be appa- rent that such a quantity would be incapable of effecting more than a mere solution of the feculent matter contained in the rectum, and of stimulating this bowel only ; for the calibre of the rectum is so great, that, under ordinary cireumstances, it can of itself contain a pint of fluid. Most commonly the cause of constipation exists in the colon; how then can the disease be relieved or removed by a clyster that is expended before it reaches this part of the canal? It will be urged, perhaps, that the superior bowels will be affected sympathetically, when the lower bowel is stimulated; but, granting this to be fact, how desirable is it to insure the good effects of an enema by admi- nistering a quantity sufficient to reach the offending part of the intestinal tube | But this could not be done by any of the ex- isting instruments, as not one of them was of a size to contain a sufficient quantity of fluid; and, if they had been, it would have required a greater degree of power to force it into the bowels, than could have been conveniently or safely directed. I may, perhaps, be asked, why a large quantity could not be applied by recharging the instrument, or by discharging other instruments ready filled, and placed at hand for that purpose ? I need not point out the fallacy of this argument to medical men, practically acquainted with the operation; for they are well aware of the difficulties which suspending the operation would present to the introduction of separate portions of fluid, as the comatus ejiciendi is generally so quickly excited, as to leave º: a short interval between the injection and expulsion.” 04. An instrument was therefore wanted, that was capable of throwing up any quantity desired, in one continuous operation, and the patent syringe most completely effects this. Again, mechanical distension can only be effected by an instrument affording power with volume ; an attention to hydraulic prin- ciples shews how both these are yielded by the syringe that | Mr. Read has constructed. The bulk of the fluid contained in the instrument is so small, that the force necessary to propel it | scarcely requires the efforts of an infant; but the effects of | these efforts, multiplied by repetition, increase to an almost infinite ratio, and at length present an overwhelming force, capable of bearing down all opposition, and overcoming all natural restraints. To try the power of the syringe, Mr. Read fixed the injecting pipe firmly into the rectum of an animal that had been recently killed, and proceeded to pump into the bowels a large quantity of water, and he continued the opera- tion with the same ease and freedom, until the intestinal canal, stretched beyond its tone, burst with the distending force. In corroboration of the good effects of this instrument in obstruc- tions of the bowels, we shall take leave to extract the following remarks from some of the most respectable medical publica- tions of the present time. “Dr. Chisholm has related a case of obstinate constipation of the bowels, relieved by Read’s Injecting Machine, after various other means had failed. The obstruction had existed three or four days before Dr. Chisholm saw the patient with Mr. Beet, surgeon; of Ashford. When seen by Dr. Chisholm, the patient’s extremities were cold, and stercoraceous vomiting had come on. A tepid solution of yellow soap was prepared, and more than a wash-hand basin full was gradually but per- severingly thrown up by means of the instrument above men- tioned, and prevented from returning by napkins pressed to the anus. The patient’s belly now resembled a drum. When the injection was allowed to come away, the spectators had the gratification to find it mixed with faeces. Shortly after this, the patient passed flatus and stools, and all the bad symptoms quickly vanished. “I have had many other causes,’ says Dr. Chisholm, ‘where Read’s Machine was of infinite service, and I think every medical practitioner should have one of these instruments in his possession.’”—Med. Repository, No. 1, new Series, page 944. - - - The author of The Village Doctor, under the article Costive- ness, (page 104,) makes the following remark: “But the use of clysters is in every way preferable to purgative medicines, and those who are costive should provide themselves with Read’s Patent Syringe, and administer a pint of the domestic enema every day at a certain hour, until the bowels act without.” . The following remarks are to be seen in Dr. Johnson's Quar- terly Review : “For many months past we have been in the habit of employing Mr. Read's Patent Injecting Apparatus, which is so small as to be carried in the waistcoat pocket, and so powerful as to throw fluids to a great distance. The object of our present notice, however, is to inform our readers that Mr. Read has adapted to the instrument a flexible elastic tube, most admirably calculated for throwing fluids into the stomach, and then extracting them in cases of poisoning. We have at- tentively examined the instrument, and we know it is approved of by Sir A. Cooper, and some of the first surgeons of the Metropolis; we think it of so much importance, that we seri- ously recommend it to every private practitioner.”—Vol. iv. No. 15, page 742, of the Medico-Chirurgical Review. In treating upon iliac passion, an author, before mentioned, says, “A copious injection of six or eight quarts of warm water, or gruel, will be the most likely means of removing the obstruc- tion, restoring the bowels to their proper situation, and of softening and bringing away those hardened motions, which accumulate in the bowels, and occasion the complaint. For this purpose (as well as for the injection of tobacco smoke,) Read’s patent syringe is preferable to all other instruments. and should be in the possession of every family.”—Scott’s “Village Doctor,” page 166. - We are informed by some medical gentlemen who have used it, that in violent cases of memorrhagia, they have been able to check the disease more effectually by an alum injection thrown by the force which the patent syringe affords, than by any other ſºlòallS. 11 S 986 S Y R. S Y R. DICTIONARY OF MECHANICAL SCIENCE. Directions for Using the Enema Apparatus.—We shall close our subject by the following explanation of the manner of using the enema apparatus:—Fix the enema tube to the lateral branch of the syringe, and put the fluid to be injected into a wash-hand basin, or other convenient vessel; the ivory pipe being inserted into the rectum, and the extremity of the syringe into the fluid, the pump may be worked, either by the patient or some other person; but the facility with which it can be accomplished by the former, by fixing the curved pipe to the tube, renders it truly valuable for domestic use. . The following extract of a letter, dated General Infirmary, Northampton, December 4, 1824, and addressed to Mr. Read, shews the practical utility of his invention:—“A boy, nine years of age, was discovered at eight o'clock in the morning of the 12th ult, in nearly a lifeless-state. On investigation it was ascertained that he had taken, by mistake, a solution of opium three hours before. He was lying in a deep stupor, his respiration very slow, and accompanied with a convulsive catching; his feet, hands, and face livid, and no pulse to be felt at the wrist. He was immediately roused up, and violently shaken, when he uttered a few incoherent cries. A quart of warm water was instantly injected into the stomach by means of your syringe, and then withdrawn; the fluid was brown, and the smell of opium plainly perceptible. Another quantity of water was then thrown in, and withdrawn ; it returned colour- less, and without any smell.—The boy was now moved con tinually about for some time, and his senses gradually returned. As soon as he could swallow, he was made to drink two ounces of ipecacuanha wine, with a drachm of sulphate of zinc, dis- solved in half a pint of warm water. This not operating, in twenty minutes a second dose was given as strong as the first, and in ten minutes afterwards the boy shewed a disposition to vomit: this was effectually excited by injecting a hand-basin full of warm water, by which I made sure that his stomach should be completely washed of any remains of the poison. After the vomiting was over, he was kept in motion three or four hours, taking at intervals a strong decoction of coffee: by the afternoon of the same day I had the pleasure of finding him perfectly well.—It is almost unnecessary to observe, that as the opium had been swallowed three hours, (and that too upon an empty stomach,) no emetic medicine would have operated until the poison was withdrawn, the fibres of the stomach being rendered perfectly inert by the stupefactive effect of the drug; indeed he had totally lost the power of swallowing; it is there- fore pretty evident, that the boy’s life would not have been saved, but for the very useful instrument of which you have the merit of being the inventor. I am, sir, with much respect, your obedient servant, CHARLes Witt, House Surgeon.” “ Approved, C. Bouverie, Chairman of the Committee.” SYRINGE, applied to Veterinary Practice.—“A righteous man regardeth the life of his beast.” Proverbs, chap. xii. v. 10.- Fig. 1, a, enema tube for horses; b, ditto do. dogs; c, vessel containing the injecting fluid, Fig. 2, injecting apparatus for hoven or blown cattle ; d, the oesophagus tube for bullocks; e, ditto do. sheep. - Animals, as well as man, are liable to accidents and disor- ders, that demand the aid of medical surgery; and among these, the occurrence of constipation and obstruction of the bowels, and of the fatal effects of excessive abdominal disten- sion, from an undue quantity of improper food, frequently brings a most useful and highly valued animal into a situation of the utmost danger. Examples of the former are constantly expe- rienced with horses and dogs. The former possesses a ten- dency to costiveness, from the dry nature of the food with which they are supplied, under the general routine practice of feed- ing ; and they are rendered still more susceptible of this state, and consequently of obstruction and even inflammation, by protracted and heavy labour, and by neglect or improper ma- nagement after severe exercise. It is also a well-ascertained fact, that the sports of the field induce a costive state of the bowels of dogs, that often reduce the animal’s condition and health, and not unfrequently destroy his life. The attention of Sportsmen, and gentlemen cannot, therefore, be too seriously drawn to this subject; and we present to their consideration an instrument by which the lives of many valuable animals have been saved, when every other means had failed. By means of the apparatus represented by fig. 1, enemas may be easily administered either to horses or dogs: and the instru- ment is such as to admit of any quantity being injected that Gº-E 2 ſīm ºśWºr; < * : * sº º 㺠ºr. x- º - Fººs à: º E-3 *** may be considered applicable to the size of the animal and to the nature of the case. The engraving, fig. 1, represents the action of the instrument; the tube being screwed to the side branch of the syringe, and the pipe introduced into the bowels, the extremity of the syringe is held in the fluid to be injected (which is put into a pail or other convenient vessel) and the piston being put into action, the clyster passes freely into the intestines. The facility afforded by this instrument, of throw- ing fluids into the bowels of animals, was demonstrated by an experiment performed at Charlton Mews, before Mr. Goodwin, his majesty’s veterinary surgeon, in which Mr. Read injected a clyster of three gallons in two minutes. - The next consideration, as to the applicability of the instru- ment, is to the cases of hoven (or blown) cattle. The frequency of this occurrence to bullocks and sheep, from overgorging with potatoes, turnips, flax-seed, ground meal, green clover, or any moist or succulent food, is unfortunately well known to the agriculturist, and every person practically engaged in the breed and management of stock; and it has been often experienced, that the means generally resorted to in those cases are but too frequently ineffective. The failure may be accounted for by observing how inadequate either puncture in the loin, or the introduction of Monro's tube, is to the evacuation of the offend- ing matter: if this were merely gas, either of the above means would probably liberate it; but it should be known that the stomach is filled by a fermenting pultaceous mixture of solids, fluids, and gas, that cannot be discharged in the manner of gas simply. The patent syringe, before described, is found to be as exactly applicable for this as for any other purpose ; and Mr. Read has prepared tubes to be fixed to it, either for sheep or bul- locks, see plated. e. Fig. 2, shews the operation of extracting the contents of the stomach of a blown bullock; the tube is passed into the stomach, and the syringe being fixed to it, and put into action, the offending matter is discharged at the side opening. Horticultural and Domestic Uses of the Patent Syringe. Nu- merous and important as the uses of the patent syringe are in animal application, its utility is capable of a still further extension. For watering pines and all other plants in conserva- tories and hot-houses, and for the destruction of insects upon trees in forcing-houses or on walls, it far exceeds the barrow- engine in the facility of its application. The Horticultural Society of London, to mark their approbation of it, honoured the patentee by conferring upon him their silver medal for the invention. It has of late been much used for washing the windows of houses and carriages, and is found to be a most effective apparatus for fumigating trees and hot-houses. This instrument also, in case of need, is an excellent fire- engine, as from it portability it can be applied to the first break- ing out of a fire, when no sort of assistance could be derived S Y T S Y T 987 DICTIONARY OF MECHANICAL SCIENCE. from the engines of the Insurance Companies, and its utilility in this way having been proved by actual experience, most of the Fire Offices have prepared themselves with it, and it is now very properly finding its way into private families, as a safe- guard against the destructive and hazardous effects of fire. Having thus described the uses of this simple but valuable invention, we close the subject, with the following statement of the whole expense of the apparatus:—Price of the enema ap- paratus £2, 12s. 6d. and with the tobacco canister, É3. 3s.-Price of the poison apparatus, £3.10s.-The catheter 6s.-The nipple glass 6s.-and the cupping glasses 68. each. SYRINGOTON, the name of an instrument to lay open the fistula. SYRUP, an agreeable liquor or composition, of a thick con- sistence, made of juices, tinctures, or waters, of fruits, flowers, or herbs, boiled up with sugar or honey, in order to preserve the compound from spoiling by fermentation, or otherwise. Syrups furnish an almost endless variety. SYSTEM, in general denotes an assemblage or chain of principles and conclusion; or the whole of any doctrine, the several parts whereof are bound together, and depend on each other. SYTHE, the subject of the Hainault sythe having excited considerable interest, we present our readers with an engrav- ing, and an account of it extracted from the Farmer's Magazine of August, 1825. This instrument was brought under the notice of the Directors of the Highland Society of Scotland so far back as June, 1823. The summer general meeting passed over, and no funds could be voted to defray the necessary expense of trial that season; the directors could only recommend to the mem- bers and their friends, who might travel in Flanders during the then ensuing harvest, to obtain information respecting it on the spot ; and, with a view to the ulterior proceedings contem- plated, the deputy-secretary was directed to procure two of the sythes. Many of our readers must have heard of the trials made several years ago with the Hainault sythe on the farm of Mudiford, near Christchurch, belonging to Sir George H. Rose. This gentleman had employed a Flemish labourer, a prisoner of war, to teach his people the use of it; and some of them, it ap- pears, had acquired great proficiency, and were able to instruct others. The first experiments were reported in the newspapers, and attracted a good deal of notice at the time; and yet it does not appear that this had the effect of introducing it into general use even in that neighbourhood. Whatever may have been the cause of this, it is certain, that its comparative merits were neither unknown nor unappreciated in other quarters. Mr. Warden, Sir George's bailiff, after this gentleman had let his farm, on being appointed to the embassy at Berlin, had in- structed the reapers of Colonel Hughes, near St. Asaph, and those of ‘Sir Watkin W. Wynne, at Wynnestay. It appears | also, from recent information, that the Hainault sythe, if not in common use, is at least well known in different parts of Wales, as well as of England, and that it was tried some time back as far north as Aberdeenshire. The directors of the Highland Society were not ignorant of all this; but, knowing the diffi- culties which a new implement has to encounter before it can be subjected to a sufficient number of well-conducted experi- ments to have its merits decided on, difficulties which could not fail to be increased by this being a foreign implement, and probably often used by unskilful hands,--they resolved, notwith- standing, to put the question at rest by having it tried in a variety of situations, and with the different kinds of crops; and that these trials should not be confined to one or two districts, but made throughout most of the corn counties of Scotland, under the inspection of the local agricultural societies. Such an arrangement, it is evident, was well calculated to make the merits of the implement extensively known, and, at the same time, to afford an opportunity to the labourers of almost every part of Scotland to learn how to work with it. Through the kind offices of M. the Chevalier Masclet, consul of France, two hands, the sons of small farmers, were engaged in French Flanders, and brought over at the expense of the society. They arrived at Edinburgh on the 12th of July; on the 15th, they were employed in reaping with the Hainault sythe on the farm of Lochend, belonging to Mr. Oliver, in the neighbourhood of the city, before a great concourse of spectators; and the day following they set out on the route assigned them by the so- ciety, through East Lothian, and the counties of Berwick and Roxburgh, practising one or two days near the principal towns. On the 22d they were at Dalkeith, from whence they were to proceed to Lanarkshire, Renfrewshire, the Carses of Stirling and Gowrie, and the counties of Fife, Forfar, Aberdeen, and Moray, and perhaps still farther north, if the duration of the harvest will admit of it. The members of the Highland Society, abounding in every part of Scotland, and most of them at this season, in the country, engaged to attend the trials in the several districts; while the local agricultural societies entered into the measure with a degree of spirit and liberality, (having offered, of their own accord, to relieve the Highland Society from part of the general expense,) which have not often been equalled, and which are to be found, to the same extent, and among the same class, in no other country than Britain. Still further to insure accurate and full reports, the Highland Society circulated printed queries, to direct the attention of those who attend the trials to the most important circumstances. The following is the result of experiments made in East Lothian, Berwickshire, and Roxburghshire, that is, in the best cultivated counties in Scotland, in the following terms: “On the 16th and 17th, the use of the instrument was exhibited on the farm of Amisfield Mains near Haddington, in presence of the Marquis of Tweeddale, the Earl of Lauderdale, Mr. Hay of Spot, Mr. Hunter of Thurston, Mr. Balfour of Whittinghame, Mr. Rennie of Phantassie, Mr. Bogee of Woodhall, and many of the most eminent agriculturists in East Lothian; and we have been favoured by an intelligent spectator with the follow- ing account, accompanied by a few remarks: - “The first trial was made upon a field of strong wheat, and in two hours and a half the reapers cut down about a quarter of a Scots acre, though they were somewhat interrupted with stones. This trial satisfied the gentlemen present, that where land is free of stones, two reapers with the Hainault sythe might cut an acre of strong corn in a day, and that it will be cut closer, and with as little loss in shaking, as with the com- mon sickle. On the second day the reapers cut some barley and oats ; and though the superiority of the implement was not so evident as on the first occasion, (the corn being much lighter on the ground,) it was on the whole very satisfactory. They finished by another trial in the wheat field. “There appeared some difference of opinion as to the advan- tage of using this implement on all occasions, but there is only one opinion as to its decided superiority in cutting strong stand- ing corn. Care must be taken, however, to clear the land of stones; and where this is done, the crop will be cut closer, and as clean, with the Wainault sythe, as it can be by the modes practised in this country, and at considerably less expense. “On the evening of the 17th, the party proceeded to Dunse; and next day exhibited, in a field of barley belonging to Mr. Logan, of Crumstain, in the presence of General Maitland, Mr. Hay, of Dunse Castle, and a number of the most respect- able farmers in the neighbourhood. The barley was a heavy crop ; and in an hour the two reapers cut 606 square yards, equal to one-eighth of an English acre, or at the rate of one acre three-eighths in a day of eleven hours. Those who witnessed the work stated, that it would require five of their best Irish reapers to cut the same quantity in the same time. The trial gave great satisfaction, and several gentlemen took immediate steps to enable some of their workmen to employ the sythe. “Having arrived at Kelso on the evening of the 18th, arrange- ments were made for a short trial the next day, to suit the con- venience of farmers attending the market; whilst Saturday, the 20th, was set apart for putting the abilities of the reapers to a full and fair test. Accordingly, on Friday afternoon, the use of the instrument was exhibited for about an hour, on Mr. Dudgeon’s farm of Spylaw, to a very great concourse of specta- tors, all of whom appeared to take a most lively interest in the scene, and to derive much satisfaction from it. Next day the reapers were again upon the same ground about ten o'clock, and proceeded to work an hour on a very heavy crop of barley. They cut 726 square yards, which, on a day’s work of ten hours, is at the rate of three-fourths of an English acre to each reaper. The ground was rather stony, and some impediment from the erowd was unavoidably sustained, otherwise, as asserted by the 988 s Y T S Y T DICTIONARY OF MECHANICAL SCIENCE. reapers, they would have done at the rate of an acre each at least. At first several binders tied and set up the sheaves; afterwards one man undertook the task, and performed it: but he declared he could not have gone on throughout the day, and it was evidently too much for one of the best workers to ac- complish. . . . . . . . . . . . . . . - - “The next trial took place upon some very light oats, arid it certainly proved that the sythe was quite effectual on crops of that description, a fact which was very generally doubted. . As there happened to be no wheat ready for cutting on Spylaw, the next and third trial was made upon a field of wheat near Kelso; a very fair crop, and the ground free from large stones. The day, being far spent, the time was limited to a quarter of | an hour, and the result was 212 yards, or at the rate of one acre and three-fourths, English measure, per day of ten working hours; and here again the obstructions from the crowd were very considerable. The whole corn taken down was cut closer ...to the ground, and cleaner, than by the sickle. Three of the best reapers with the sickle, cut an English acre per day, mak- ing also bands for the sheaves; but five are often found scarcely equal to the same work. - “These experiments were witnessed by a committee of the Highland Society, a Committee of the Union Agricultural So- ciety, and a number of proprietors and eminent agriculturists; and at intervals a number of intelligent and active workers, who had been brought forward for the purpose, were allowed to use the scythes, and received instructions from the Flemings; and many of them shewed considerable expertness. “The two young Flemings are sons of farmers in French Flanders, (where farms seldom much exceed 100 acres,) and their names are J. B. Dupre, and Luis Catteau, the first from the neighbourhood of Douay, the other from near Lille. Their behaviour is modest and unassuming; they are very intel- ligent, and shew a most praiseworthy anxiety for information, particularly in statistical and agricultural matters, on which they take numerous notes. They allege they cannot do so much work as the labourers in their own country, who depend solely for subsistence on their daily toil. To a question pointedly put to them, if the sythe could be used with advantage when the crop was on an acclivity ? they unhesitatingly replied, ‘Equally well as on a level piece of ground;’ and offered to prove it.’ Description of the Plate. This implement, called in England the Hainault sythe, is known in French Flanders under the name of Piquet, or Petite Faula, (small sythe.) It is composed of two parts, fig. 1 and 2. Fig 1 represents the piquet. The blade A to B, is 21 inches long and 2% inches broad. The back is ; of an inch thick. The blade is fixed into the handle by one or rather two wedges I, I. The handle from I to C. is seven- teen inches long. At C it is curved; the length from C D, 5% inches. The part F, G, E, is, from F to G, 3} inches wide, Iſāg J’. and from D to E, 4 inches long. This serves as a balance to help the workman. At H is a small leather strap, in which the work- C man inserts his fore-finger. In this point, where they place their fore finger, is the centre of gra- vity. Fig. 2 is called the crochet (the hook.) The workman uses it with his left hand, to gather the quantity of corn he intends to cut, to support it when he is cutting, and lay it afterwards behind him. This hook has a handle, A, B, of the length of three feet five inches; its shape is square; it has at the top an iron hook nailed on the wood: its length from A to C is 10; inches. The small opening above B is for the purpose of inserting the blade, so as to prevent the workman being hurt, when carrying his implement. r T. T A B T, the nineteenth letter of our alphabet. In Abbreviations, amongst the Roman writers, T. stands for Titus, Titius, &c. Tab, for Tabularius; Tab. P. H. C. for Tabularius provincis Hispaniae citerioris; Tar. Tarquinius; Ti. Tiberius; Ti. F. Tiberii filius; Ti. L. Tiberii libertus; Ti. N. Tiberius Nepos; T. J. A. W. P. V. D. tempora judicem arbitrumve postulat ut det; T. M. P. terminum posuit; T. M. D. terminum dedica- vit; Tr. trans. tribunus; Tr. M. or Mil. tribunus militum ; T. R. P. L. D. E. S. triannus plebis designatus; T. R. A. E. R. tribu- nus aerarii; T. W. R. C. A. P. triumviri capitales; T. R. or TRIB. POT. tribunieia potestata; Tul. H. Tulus Hostilius. TABBY, in Commerce, a kind of rich silk which has under- gone the operation of tabbying; or being passed through a calender, the rolls of which are made of iron or copper, vari- ously engraven; which bearing unequally on the stuff, renders the surface unequal, so as to reflect the rays of light differently, making the representation of waves thereon. TABLE, in Perspective, denotes a plane surface, supposed to be transparent, and perpendicular to the horizon. It is always imagined to be placed at a certain distance between the T A C eye and the objects, for the objects to be represented thereon by means of the visual rays passing from every point thereof º the table to the eye; whence it is called perspective plane. TABLE, among the Jewellers. A table-diamond, or other precious stone, is that whose upper surface is quite flat, and the only sides cut in angles; in which sense, a diamond cut table- wise, is used in opposition to a rose-diamond. TABLE, in Mathematics, systems of numbers calculated to be ready at hand for the expediting astronomical, geometrical, and other operations: thus, we say tables of the stars; tables of sines, tangents, and secants; tables of logarithms, rhumbs, &c.; sexagenary tables. TABLING, a sort of broad hem, formed on the heads, skirts, and bottoms of a ship's sails, to strengthen them in that part which is attached to the bolt-rope. TACCA, a genus of the class and order hexandria monogynia. TACHY GRAPHY, the art of writing fast, or of short hand; of which authors have invented several methods. TACK, a rope used to confine the foremost lower corners of T A c .989 DICTIONARY OF MECHANICAL SCIENCE. T A { the courses and stay-sails, in a fixed position, when the wind crosses the ship's course obliquely. The same name is also given to the rope employed to pull out the lower corner of a studding-sail to the extremity of its boom. The main-sail and fore-sail of a ship are furnished with a tack on each side, which is formed of a thick rope, tapering to the end, and having a knot wrought upon the largest end, by which it is firmly re- tained in the clue of the sail ; the tack therefore extends the sail to windward, while the sheet GXtends it to leeward. TAck, is also applied, by analogy, to that part of any sail to which the tack is usually fastened. A ship is said to be on the starboard or larboard tack, when she is close-hauled with the wind on the starboard or larboard side, and in this sense the distance she sails in that position is considered as the length of the tack, although this is more frequently called a board. To Tach, to change the course from one board to another, or turn the ship about from the starboard to the lar- board tack, or vice versa, in a contrary wind. It is performed by turning the ship's prow suddenly to the wind, whereby her head-sails being thrown aback, they receive the impression of the wind in a new direction, and cause her to fall off from the wind to the other tack. - TACKING, is also used in a more enlarged sense, to imply that manoeuvre by which a ship makes an oblique progression to windward, in a zig-zag direction ; this, however, is more usually called beating or turning to windward. The operation of tacking is thus performed: the helm being put to the lee- side, the commanding-officer calls out, ‘Helm a-lee;’ the head- sails are immediately made to shiver in the wind, by casting Hoose their sheets and bow-lines; the officer then calls, “Raise tacks and sheets,’ which is executed by looseming all the ropes which confine the corners of the lower sails, in order that they may be more readily shifted to the other side. When the ship has turned her head directly to the wind, the order is given to turn about the sails on the mizzen-mast, by the exclamation, * Haul main-sail, haul;’ the bow-lines and braces are then instantly let go on one side, and as expeditiously drawn in on the other side, so as to wheel the yards about their masts; the lower corner of the main-sail is, by means of its tack, pulled down to its station at the chess-tree, and the after-sails are at the same time adjusted to stand upon the other board. Finally, when the ship has fallen off five or six points, the commanding- officer calls, “Haul off all,” or, ‘Let go and haul ;’ then the sails on the foremast are wheeled about by their braces, and as the ship has a tendency to fall off, she is checked by the effort of the helm, which is for that purpose shifted to the now lee-side. The fore-tack, or lower corner of the foresail, being fixed in its place, the bowlines are hauled, and the other sails are properly arranged to the wind, which is called trimming all sharp. In order to explain the theory of tacking a ship, it may be neces- sary to premise a known axiom in natural philosophy, that every body will persevere in a state of rest, or of moving uni- formly in a right line, unless it be compelled to change its state by forces impressed, and that the change of motion is propor- tional to the moving force impressed, and is made according to the right line in which that force is exerted. By this principle it is easy to conceive how a ship is compelled to turn in any direction by the force of the wind acting upon her sails in hori- | zontal lines. For the sails may be so arranged as to receive the current of air either directly, or more or less obliquely; hence the motion communicated to the sails must of necessity conspire with that of the wind upon their surfaces. To make the ship tack, or turn round with her head to the windward, it is therefore necessary, after she has received the first impression from the helm, that the head-sails should be so disposed as to diminish the effort of the wind, in the first instant of her motion, and that the whole force of the wind should be exerted on the after-sails, which, operating on the ship’s stem, carries it round like a weathercock. But since the action of the after-sails to turn the ship will unavoidably cease when her head points to the windward, it then becomes necessary to use the head-sails to prevent her from falling off, and returning to her former situation. These are accordingly laid aback on the lee-side, to push the vessel's forepart towards the appointed side till she has fallen into the line of her course thereon, and fixed her sails to conform with that situation. 105. e surface. TACKLE, a machine formed by the communication of a rope with an assemblage of blocks, and known in mechanics by the name of pulley. Tackles are used in a ship to raise, remove, or secure weighty bodies, to support the masts, or to extend the sails and rigging; they are moveable, as communicating with a runner, or fixed, as being hooked in an immoveable situation; and they are more or less complicated in proportion to the effects which they are intended to produce. The appli- cation of the tackle to mechanical purposes is called hoisting or bowsing. Ground Tackle, implies the anchors, cables, &c. Tach Tackle, a small tackle used to pull down the tacks of the principal sails to their respective stations, and particularly attached to the main-sails of brigs, sloops, cutters, and schoon- ers. For various other tackles, see their particular epithets. TACTICS, in the art of War, is the method of disposing forces to the best advantage in order of battle, and of perform- ing the several military motions and evolutions. TAENIA, in Natural History, Tape Worm. Gmelin has enumerated almost one hundred species, besides varieties: he has divided them into sections. A. Those found in other parts besides the intestines, and furnished with a vesicle behind. B. Those found in the intestines only, and without a terminal vesicle. C. Those with the head unarmed with hooks. The worms of the first section are found infesting mammalia, rep- tiles, and fish. Those of the second section are found in the . matmmalia, in birds, and in fish; and those of the third section infest mammalia, birds, reptiles, and fish. This genus of worms are destined to feed on the juices of various animals, and are usually found in the alimentary canal, generally at the upper part of it. They are sometimes found in great numbers, and occasion the most distressing disorders. They have the power of reproducing parts which have been broken oſf, and are there- fore removed with the utmost difficulty: they are oviparous, and discharge their eggs from the apertures on the joints. TAFFAREL, the uppermost part of a ship's stern; being a curved piece of wood, and usually ornamented with some device in sculpture. TAIL of A GALE, a name given by sailors to the latter part of a storm, wherein its violence is considerably abated. TAIL-Block, a single block, having a short piece of rope attached to it, by which it may be fastened to any object at pleasure, either for conveyance, or to increase the force applied to the said object. - TAKING-IN, among Seamen, the act of brailing up and furl- ing the sails at sea, particularly when the wind increases; and is generally used in opposition to setting. TALC, in Mineralogy, a stone, the characters of which are, a specific gravity between 3:5834 and 2-9902; a texture easy to be scraped with the knife; a soft and unctuous surface; the primitive form of a right rhomboidal prism, its bases having angles of 120 degrees and 60 degrees, and in which sections parallel with these bases are easily obtained. Its integrant molecule has the same form. - TALENT, a money of account amongst the ancients, equal to £342 sterling. Among the Jews, a talent in weight was equal to 60 maneh, or 113 pounds, 10 ounces, 1 penny weight, 10 and two-seventh grains. TALES is used in Law, for a supply of men impannelled on a jury, and not appearing, or on their appearance challenged and disallowed, when the judge, upon motion, orders a supply to be made by the sheriff of one or more such persons present in court, to make up a full jury. º - TALLOW, animal fat melted down and clarified; but the name is frequently given to this unctuous substance in its most simple state. After domestic purposes are supplied, the great consumption is in the making of soap and candles, and in the dressing of leather. TAllow Tree. In China this tree grows in great abundance. It is about the height of a pear tree, and in habit it resembles that of the cherry. The seeds, which are numerous, are sepa- rated from the white substance in which they are enclosed, by being steeped ten or fifteen days in water; after which, being put into a press, a glutinous oil drops from them, which soon hardens into the consistence of animal tallow. Thé seed is also sometimes boiled in water, when the oil is found floating on its Candles made of this substance are very white, and, 11 T 990 T A. N. T A R DICTIONARY OF MECHANICAL SCIENCE. according to Sir George Staunton, are firmer than those of common tallow, as well as free from all offensive odour; but he thinks them inferior to such as are made of wax or spermaceti. The Chinese frequently colour this tallow with vermilion, to add to its bcauty. TALLY, a piece of wood, on which retailers cut notches to mark the goods delivered out on credit. Tallies are taken as evidence in courts of justice, as much as books. TALLYING-Aft, a phrase applied to the act of pulling aft the sheets or lower corners of the main-sail and fore-sail. TALMUD, or THALMUD, among the Jews, a collection of the doctrines of their religion or morality. TALPA, the Mole, a genus of quadrupeds of the order ferae. The common mole is about six inches in length, without the tail. Its body is large and cylindrical, and its snout strong and cartilaginous. Its skin is of extraordinary thickness, and covered with a fur, short, but yielding to that of no other animal in fineness. It hears with particular acuteness, and, notwith- standing the popular opinion to the contrary, possesses eyes, which it is stated to be able to withdraw or project at plea- sure. It lives partly on the roots of vegetables, but principally on animal food, such as worms and insects, and is extremely voracious and fierce. that a mole, a toad, and a serpent, have been repeatedly enclosed in a large glass vase, and that the mole has not only killed the others, but has devoured a very considerable part of them. It abounds in soft ground, in which it can dig with ease, and which furnishes it with the greatest supply of food. It forms its subterraneous apartments with great facility, by its snout and feet, and with a very judicious reference to escape and comfort. It produces four or five young in the spring, in a nest a little beneath the surface, composed of moss and herbage. It is an animal injurious to the grounds of the farmer, by throwing up innumerable hills of mould, in the construction of its habitation, or the pursuit of its food; and many persons obtain their subsistence from the premiums which are, on this account, given for their destruction. Moles can swim with considerable dexterity, and are thus furnished with the means of escape in those sudden inundations to which they are fre- uently exposed. In Ireland, the mole is unknown. TAMARICK, a large shrub much used in some parts in making quickset hedges. The French sort is chiefly used. TAMARINDUS, the Tamarind Tree, a genus of plants arranged by Linnaeus under the class of triandria and order of monogynia. The timber of the tamarind tree is heavy, firm, and hard; sawn into boards, it is converted to many useful purposes in building. The fruit is used both in food and medi- cine. In many parts of America, particularly in Curaçoa, they eat abundance of it raw, without any inconvenience. In Mar- timico also, they eat the unripe fruit, even of the most austere kind. \ TAMBAC, a mixture of gold and copper, which the people of Siam hold more beautiful and valuable than gold itself. TAMBOUR, in Architecture, a term applied to the Corin- thian and Composite capitals. e TAMBOUR, in the Arts, is a species of embroidery, in which threads of gold, silver, and silk, are formed into leaves, flowers, or other figures. TAMPING, in Mining, is the clay, or other matter, rammed into a hole made in a rock, for blasting with gunpowder. TAMPION, or ToMPIon, a stopple or plug which closes up a hole in a vessel. In Gunnery, it is a wooden cylinder put into the muzzles of cannon, &c. to prevent the dust or wet from entering. TAN, the bark of the oak chopped and ground in a tanning mill into a coarse powder, to be used in the tanning of leather. TANGENT, in Geometry, is defined, in general, to be a right line, which touches any arch of a curve, in such a manner that no right line can be drawn betwixt the right line and the arch. TANNIN. This, which is one of the immediate principles of vegetables, was first distinguished by Seguin from the gallic acid, with which it had been confounded under the name of the astringent principle. He gave it the name of tannin, from its use in the tanning of leather, which it effects by its charac- teristic property, that of forming with gelatin a tough insoluble matter. - Shaw relates, from Sir Thomas Brown, . TANNING. The several kinds of leather are prepared from the skins of animals, macerated for a long time with lime and water, to promote the separation of the hair and wool, and of the fat and fleshy parts, in which recourse is also had to the assistance of mechanical pressure, scraping, and the like. The skin, when thus deprived of its moist putrescible part, and brought considerably toward the state of mere fibre, is tanned by maceration with certain astringent substances, particularly the bark of the oak tree.—The hide consists almost wholly of gelatin, and all that is necessary is, to divest it of the hair, epidermis, and any flesh or fat adhering to it. This is com- monly done, after they have been soaked in water some time, and handled or trodden to cleanse them from filth, by immers- ing them in milk of lime. Some, instead of lime, use an acescent infusion of barley or rye meal, or spent tan; and others recommend water acidulated with sulphuric acid. Similar acidulous waters are afterwards employed for raising or swelling the hide, when this is necessary. The skins thus prepared, are finally to undergo what is properly called the tanning. This is usually done by throwing into a pit, or cistern, made in the ground, a quantity of ground oak bark that has already been used, and on this the skins and fresh bark in alternate layers, covering the whole with half a foot of tan, and treading it well down. The tanning may be accelerated by adding a little water. TANTALITE, a metallic fossil. , Colour between bluish-grey and blackish-grey. Surface smooth, with some lustre. Lustre metallic. Fracture compact. Streak blackish grey, approach- ing brown. Very hard. Not magnetic. Specific gravity 7.953. Composed of the oxides of tantalian, iron, and manganese. TANTALUS, the Ibis, in Natural History, a genus of birds of the order grallae. There are nineteen species, of which we shall notice the following. T. loculator, the wood ibis, is of the size of a goose, and the T. ibis or the Egyptian ibis, is more than three feet long, and as large as a stork. On the retreating of the Nile, it is found in Lower Egypt in great numbers, subsist- ing on insects and frogs. It perches on palm trees, and sleeps in an erect attitude, its tail touching its legs. It is supposed by some naturalists to be the ibis of the ancients, and is known to destroy and devour serpents. TAPESTRY, a kind of woven hangings of wool and silk, fre- quently raised and enriched with gold and silver, representing figures of men, animals, landscapes, histories, &c. TAPIR, the name of an animal found in some parts of Ame- rica. In size, it is about that of a stout calf, and in shape bears some resemblance to a hog. - TAPPING, the act of piercing a tree or barrel, to extract its juices or liquor. In Surgery, it is an operation performed on dropsical persons. TAR, a thick, black, unctuous substance, obtained from old pines and fir trees by burning them with a smothering heat. TAR, a kind of liquid gum, which is procured from pines or fir-trees, and is used to pay the sides of ships and boats, and their rigging and yards, in order to preserve them from the effccts of the weather. TARANTULA, a species of spider, the bite of which it is extremely difficult to cure; and, even after a cure has been effected, the patient has usually some annual affection, from the latent poison of the insect. TARE, in Agriculture, a plant of the vetch kind, of which there are two sorts. TARE, is an allowance for the outside package that Gontains such goods as cannot be unpacked without detriment; or for the papers, threads, bands, &c. that enclose or bind any goods, imported loose; or though imported in casks, chests, &c. yet cannot be unpacked and weighed net. TARGIONIA, a genus of plants of the class of cryptogamia, and natural order of algae. - TARGUM, a name whereby the Jews call the Chaldee para- phrases or expositions, of the Old Testament, in the Chaldee language. - •-4 º TARIFF, a table or catalogue usually drawn in an alphabe- tical order, containing the names, and amount of duties paid on several kinds of merchandise. TARPAWLING, a broad piece of canvass, well daubed with tar, and used to cover the hatchways of a ship at Sea, to T A U 991 DICTION ARY OF MECHANICAL SCIENCE. T E L prevent the penetration of the rain or sea-water, which may at times rush over the decks. - TARRAS, or TeRRAs. A volcanic earth used as a cement. It does not differ much in its principles from puzzolana; but it is much more compact, hard, porous, and spongy. It is gene- rally of a whitish-yellow colour, and contains mere heterogeneous particles, as spar, quartz, schorl, &c. and something more of a calcareous earth. It effervesces with acids, is magnetic, and fusible per se. When pulverized, it serves as a cement, like puzzolana. It is found in Germany and Sweden. . See LIME. e TARTAN, a small coasting vessel navigated in the Medi- terranean sea, and having only one mast and a bowsprit, the principal sail, which is very large, being extended by a lateen ard. TARTAR, or, according to the new chemistry, tartrat of potass, is obtained in a state of impurity, incrusted on the bottom and sides of casks in which wine has been kept. 1t is after- wards purified by dissolving it in boiling water, and filtering it while hot. On cooling, it deposits the pure salt in very irre- gular crystals. In this state it is sold under the name of crys- tals or cream of tartar. - TARTARIC ACID. Scheele was the first who obtained this acid in a separate state. He communicated his process for ob- taining it to Retzius, who published it in the Stockholm Trans- actions for 1770. It consisted in boiling tartar with lime, and in decomposing the tartrat of lime thus formed by means of sul- phuric acid. The process employed at present for obtaining tartaric acid, which is the same with that of scheele, is the fol- lowing:—Dissolve tartar in boiling water, and add to the solu- tion powdered chalk till all effervescence ceases, and the liquid ceases to redden vegetable blues. Let the liquid cool, and then pass it through a filtre. A quantity of tartrat of lime (which is an insoluble white powder) remains upon the filtre. Put this tartrat, previously well washed, into a glass cucurbite, and pour on it a quantity of sulphuric acid equal to the weight of the chalk employed, which must be diluted with water. Allow it to digest for twelve hours, stirring it occasionally. The sulphu- ric acid displaces the tartaric; sulphat of lime remains at the bottom, while the tartaric acid is dissolved in the liquid part. JDecant off this last, and try whether it contains any sulphuric acid; this is done by dropping in a little acetat of lead ; a pre- cipitate appears which is insoluble in acetic acid, if sulphuric acid is present, but soluble if it is absent. If sulphuric acid is present, the liquid must be digested again on some more tartrat of lime; if not, it is to be slowly evaporated, and about one-third part of the weight of the tartar employed is obtained of crystallized tartaric acid. TARTRATS, salts formed with the tartaric acid. TASTE, a sensation excited by means of the organs of this sense, the papillae of the tongue, &c. Taste is also used in a figurative manner for the judgment and discernment of the mind. - TAUGHT, the state of being extended or stretched out, and is usually applied in opposition to slack. TAUGHT Sail, implies a great quantity of set sail. TAUNT, an epithet, at sea, signifying high or tall. It is particularly expressed of the masts, when they are of an ex- traordinary length, as square is applied to the yards on the Sam € OCCaSIOI). TAURUS, the Bull 8, is the second of the spring signs, and the sun enters it, according to the fixed zodiac of Hipparchus, on the 20th of April; but reckoning by the moveable zodiac, or the recession of the equinoxes, the transit takes place about the 12th of May. The earth is now in Scorpio, and the Sun as seen from the earth appears in Taurus, the north pole comes now more into the light, and the days increase as the nights decrease in length, at all places N of the Equator. On the 5th of May the earth is in the 15th degree of Scorpio, and the sun as seen from the earth appears in the 15th degree of Taurus. The tropic of Cancer is now in the light from a little after 5 o'clock in the morning, till about 7 in the evening ; the parallel of London, from half an hour past 4, till half an hour past 7; the polar circle from 3 till 9; and a large tract round the N pole has day all the 24 hours, for many rotations of the earth on its axis. The Hyades and Pleiades, though denominated constellations, are integral parts of Taurus. - Boundaries and Contents.--N. by Perseus and Auriga; E, by Gemini; S. by Orion and Eridanus; and W. by Aries. There are 141 stars in this constellation. TAUTOLOGY, a needless repetition of the same sense in different words. TAWING, the art of dressing the skins of sheep, lamb, kid, and goats, in white, for divers manufactures, particularly gloves. TAX, an impost laid by government on almost every thing. TAXUS, in Botany, Yew Tree, a genus of the dioecia nio- nodelphia class and order. Natural order of coniferae. The yew-tree is a native of Europe, North America, and Japan; its proper situation is in mountainous woods, or more parti- cularly the clefts of high calcareous rocks. England formeriy possessed great abundance, and it is now not very uncommon in a wild state, in some parts of the country. Of planted trees there are yet several in church-yards. TEA, a valuable shrub, that abounds in China and Japan. Its leaves only are imported into Europe, the infusion of which is too well known to require any particular description. The difference in the qualities of tea is generally thought to arise from the season in which the leaves are gathered, and the man- ner in which they are preserved. The consumption of this article, in England alone, is almostincredible. TEAK, a yaluable timber which abounds in various parts of the East Indies, and is applied to domestic and nautical pur- poses. Ships built with teak are far more durable in the Indian seas than those made of English oak. TEAL, the smallest species of bird of the duck kind. TEAM, the number of horses, oxen, or other animals, united together to draw a cart, waggon, or other carriage. TEASEL, a species of plant much used in cloth manufac- tories, for raising the nap on the article made. It is much cultivated in those districts, but in others it is considered as a , weed, and destroyed. TECHNICAL, expresses somewhat relating to arts and sci- ences; in this sense we say technical terms. It is also particu- larly applied to a kind of verses wherein are contained the rules or precepts of any art, thus digested to help the memory to re- tain them. TEETH. The basis of the substance that forms the teeth, like that of other bones, appears to be phosphate of lime. The ena- mel, however, according to Mr. Hatchett, differs from other bony substances in being destitute of cartilage; for raspings of enamel, when macerated in diluted acids, he found were wholly dissolved; while raspings of bone, treated in the same manner, always left a cartilaginous substance untouched. TELEGRAPH, is the name very properly given to an instru- ment, by means of which information may be almost instan- taneously conveyed to a considerable distance. The telegraph, though it has been generally known and used by the moderns only for a few years, is by no means a modern invention. There is reason to believe that amongst the Greeks there was somc sort of telegraph in use. A Greek play begins with a scene, in which a watchman descends from the top of a tower in Greece, and gives the information that Troy was taken : “I have been looking out these ten years (says he) to see when that would happen, and this night it is done.” Of the antiquity of a mode of conveying intelligence quickly to a great distance, this is certainly a proof. The Chinese, when they send couriers on the great canal, or when any great man travels there, make signals by fire from one day’s journey to another, to have every thing prepared; and most of the barbarous nations used formerly to give the alarm of war by fires lighted on the hills or rising grounds. Polybius calls the different instruments, used by the ancients for communicating information, fire-signals. A new method, invented by Cleoxenus, (others say Demo- critus,) and very much improved by Polybius, as he himself informs us, is as follows: Take the letters of the (Greek) alpha- bet, and divide them into five parts, each of which will consist of five letters, except the last division, which will have only four. Let these be fixed on a board in five columns. The man who is to give the signals, is then to begin by holding up two torches, which he is to keep aloft till the other palty has also shewn two. This is only to shew that both sides are ready. These first torches are then withdrawn. Both parties are provided with boards, on which the letters are disposed as formerly 992 T E L. T E L DICTIONARY OF MECHANICAL SCIENCE. described. The person, then, who gives the signal, is to hold up torches on the left, to point out to the other party from what column he shall take the letters as they are pointed out to him. If it is to be from the first column, he holds up one torch ; if from the second, two; and so on for the others. ... He is then to hold up torches on the right, to denote the particular letter of the column that is to be taken. All this must have been agreed on beforehand. The man who gives the signals must have an instrument consisting of two tubes, and so placed as that, by looking through one of them, he can see only the right side, and through the other only the left, of him whom he is to answer. The board must be set up near this instrument; and the station on the right and left must be surrounded with a wall ten feet broad, and about the height of a man, that the torches raised above it may give a clear and strong light, and that when taken down they may be completely concealed. Let us now suppose that this information is to be communicated—A number of the awa'iliaries, about a hundred, have gone over to the enemy. In the first place, words must be chosen that will convey the informa- tion in the fewest ietters possible; as, A hundred Cretans have deserted, Kpersc Skarov ag' nuwy muropoxmoav. Having written down this sentence, it is conveyed in this manner: The first letter is a K, which is in the second column; two torches are therefore to be raised on the left hand, to inform the person who receives the signals to look into that particular column. Them five torches are to be held up on the right, to mark the letter k, which is the left in the column. Then four torches are to be held up on the left, to point out the p (r), which is in the fourth column, and two on the right, to shew that it is the second letter of that column. The other letters are pointed out in the same manner. Such was the pyrsia or telegraph recom- mended by Polybius.—But neither this, nor any other method mentioned by the ancients, seems ever to have been brought into general use; nor does it appear, that the moderns had thought of such a machine as a telegraph till the year 1663, when the Marquis of Worcester, in his Century of Inventions, affirmed that he had discovered “a method by which, at a win- dow, as far as eye can discover black from white, a man may hold discourse with his correspondent, without noise made or notice taken; being, according to occasion given, or means afforded, ea re mata, and no need of provision beforehand; though much better if foreseen, and course taken by mutual consent of parties.” This could be done only by means of a telegraph, which, in the next sentence, is declared to have been rendered so perfect, that by means of it the correspondence could be carried on “by night as well as by day, though as dark as pitch is black.” Dr. Hooke, whose genius as a mechanical inventor was perhaps never surpassed, delivered a “Discourse to the Royal Society, May 21, 1684, shewing a way how to communicate one's mind at distances,” of 30, 40, 100, 120, &c. miles, “in as short a time almost as a man can write what he would have sent.” He takes to his aid the then recent invention of the telescope, and ex- plains the method by which characters exposed at one station may be rendered plain and distinguishable at the others. He directs, “ First, for the stations; if they be far distant, it will be neces- sary that they should be high, and lie exposed to the sky; that there be no higher hill, or part of the earth beyond them, that may hinder the distinctness of the characters that are to appear dark, the sky beyond them appearing white; by which means also the thick and vaporous air near the ground will be passed over and avoided.” “Next, the height of the stations is advan- tageous, upon the account of the refractions or inflections of the air.” “Next, in choosing of these stations, care must be taken, as near as may be, that there be no hull that interposes between them, that is almost high enough to touch the visible ray; because in such cases the refraction of the air of that hill will be very apt to disturb the clear appearance of the object.” “The next thing to be considered is, what telescopes will be necessary for such stations,” “One of these telescopes must be fixed at each extreme station, and two of them in each inter- mediate; so that a man for each glass, sitting and looking through them, may plainly discover what is done in the next adjoining station, and with his pen write down on paper the characters there exposed in their due order; so that there ought to be two persons at each extreme station, and three at each intermediate ; so that, at the same time, intelligence may be conveyed forwards, and backwards.” “Next, there must be certain times agreed on, when the correspondents are to expect; or else there must be set at the top of the pole, in the morning, the hour appointed by either of the correspondents for acting that day: if the hour be appointed, pendulum clocks may adjust the moment of expectation and observing.” “ Next, there must be a convenient apparatus of characters, whereby to communicate any thing with great ease, distinctness, and secrecy. And, those must be either day characters or night characters.” The day characters “may all be made of three slit deals;” the night characters “may be made with links, or other lights, disposed in a certain order.” The doctor invented twenty-four simple characters, each constituted of right lines, for the letters of the alphabet; and several single characters, made up of semicircles, for whole sentences. He recommended, that three very long masts or poles should be placed vertically, and joined at top by one strong horizontal beam; that a large Screen should be placed at one of the upper corners of this frame, behind which all the deal-board characters should hang, and by the help of proper cords should quickly be drawn for. Wards to be exposed, and then drawn back again behind the Screen, “By these means,” says the doctor, “all things may be made so convenient, that the same character may be seen at Paris, within a minute after it hath been exposed at London, and the like in proportion for greater distances; and that the characters may be exposed so quick after one another, that a composer shall not much exceed the exposer in swiftness.” Among the uses of this contrivance, the inventor specifies these: “The first is for cities or towns besieged; and the second for ships upon the seas; in both which cases it may be prac- tised with great certainty, security, and expedition.” The whole of Dr. Hooke's paper was published in Derhan's collec- tion of his Experiments and Observations; from which it appears, that he had brought the telegraph to a state of far greater maturity and perfection than M. Amonton's, who attempted the same thing about the year 1702; and indeed to a state little inferior to several which have been proposed during the last twenty years. - . During the French revolution the telegraph was applied to useful purposes. Whether M. Chappe, who is said to have invented the telegraph first used by the French about the end of 1793, knew any thing of Hooke's or of Amonton's invention, it is impossible to say ; but his telegraph was constructed on principles, nearly similar. The manner of using this telegraph was as follows:–At the first station, which was on the roof of the palace of the Louvre at Paris, M. Chappe, the inventor, received in writing, from the committee of public safety, the words to be sent to Lisle, near which the French army at that time was. An upright post was erected on the Louvre, at the top of which were two transverse arms, moveable in all direc- tions by a single piece of mechanism, and with inconceivable rapidity. He invented a number of positions for these arms, which stood as signs for the letters of the alphabet; and these. for the greater celerity and simplicity, he reduced in number as much as possible. The grammarian will easily conceive, that sixteen signs may amply supply all the letters of the alphabet, since some letters may be omitted, not only without detriment, but with advantage. These signs, as they were arbitrary, could be changed every week, so that the sign of B for one day might be the sign of M the next; and it was only necessary that the persons at the extremities should know the key. The intermediate operators were only instructed generally in these sixteen signals; which were so distinct, so marked, so different the one from the other, that they were easily remembered. The construction of the machine was such, that each signal was uniformly given in precisely the same manner at all times: it did not depend on the operator's manual skill; and the position of the arm could never, for any one signal, be a degree higher. or a degree lower, its movement being regulated mechanically. M. Chappe having received at the Louvre the sentence to be conveyed, gave a known signal to the second station, which was Mont Martre, to prepare. At each station there was a watch- tower, where telescopes were fixed, and the person on watch gave the signal of preparation which he had received, and this. communicated successively through all the line, which brought T E. L. T E L DICTIONARY OF MECHANICAL SCIENCE. 993 them all into a state of readiness, The person at Mont Martre then received, letter by letter, the sentence from the Louvre, which he repeated with his own machine; and this was again repeated from the next height, with inconceivable rapidity, to the final station at Lisle. Two working models of this instrument were executed at Frankfort, and sent by Mr. W. Playfair to the Duke of York; and hence the plan and alphabet of the machine came to Eng- land, where various experiments were in, consequence tried upon telegraphs, and one was soon after set up by government in a chain of stations from the Admiralty-office to the sea-coast. It consists of six octagon boards,” each of which is poised upon an axis in a frame, in such a manner that it can be either placed vertically, so as to appear with its full size to the observer at the nearest station, as in fig. 1, or it becomes invisible to him by being placed horizontally, as in fig. 2, so that the narrow edge alone is exposed, which narrow edge is from a distance invisible. Fig. 2 is a representation of this telegraph with the parts all shut and the machine ready to work. T, in the officer's cabin, is the telescope pointed to the next station. Fig. 2, is a represen- tation of the machine not at work, and with the ports all open. Fig.2. The opening of the first port (fig. 1) expresses a, the second b, - the third c, the fourth d, the fifth e, and the sixth f, &c. Six boards make 36 changes, by the most plain and simple mode of working: and they will make many more, if more were neces- sary; but as the real superiority of the telegraph over all other modes of making signals consists in its making letters, we do not think that more changes than the letters of the alphabet, and the ten arithmetical ciphers, are necessary; but, on the contrary, that those who work the telegraphs should avoid com- municating by words or signs agreed upon to express sentences; for that is the sure method never to become expert at sending unexpected intelligence accurately. Several other telegraphs have been proposed to remedy the defects to which the instru- ment is still liable. The dial-plate of a clock would make an excellent telegraph, as it might exhibit 144 signs so as to be visible at a great distance. A telegraph on this principle, with only six divisions instead of twelve, would be simple and cheap and might be raised 20 or 30 feet high above the building, with- out any difficulty; it might be supported on one post, and there- fore turn round, and the contrast of colours would always be the same. A very ingenious improvement of the telegraph has been proposed in the Gentleman’s Magazine; it consists of a semi- circle to be properly elevated, and fixed perpendicularly on a strong stand. The radius 12 feet; the semicircle consequently somewhat more than 36. This is to be divided into 24 parts. Each of these will therefore comprise a space of 18 inches, and an arch of 7° 30' on the circumference. These 24 divisions to be occupied by as many circular apertures of six inches dia- meter; which will leave a clear space of six inches on each * The form is now altered, and a single pole with moveable arms conveys intelligence. - 105. side between the apertures. These apertures beginning from the left, to denote the letters of the alphabet, omitting K, J, consonant, W, X, and Q, as useless for this purpose. There are then 21 letters. The four other spaces are reserved for signals. The instrument to have an index moveable by a windlass on the centre of the semicircle, and having two tops, according as it is to be used in the day or night; one, a circular top of lacquered iron or copper, of equal diameters with the apertures (and which consequently will eclipse any of them against which it rests); the other a spear or arrow-shaped top, black, and highly polished, which in standing before any of the apertures in the day-time will be distinctly visible. In the night, the apertures to be reduced by a diaphragm sitting close to each so as to leave an aperture of not more than two inches diame- ter. The diaphragm to be of well-polished tin; the inner rim lacquered black half an inch. All the apertures to be illumi- nated, when the instrument is used in the night-time, by small lamps; to which, if necessary according to circumstances, con- vex lenses may be added, fitted into each diaphragm, by which the light may be powerfully concentrated and increased. Over each aperture one of the five prismatic colours least likely to be mistaken (the remaining two being less distinguishable, and not wanted, are best omitted) to be painted; and, in their natural order, on a width of eighteen inches and a depth of four, red, orange, yellow, green, blue; or, still to heighten the con- trast, and render immediately successive apertures more dis- tinguishable, red, green, orange, blue, yellow. The whole inner circle beneath and between the apertures to be painted black. When the instrument is to be used, the index to be set to the signal apertures on the right. All the apertures to be covered or dark when it begins to be used, except that which is to give the signal. A signal gun to be fired, to apprize the observer. If the index is set to the first aperture, it will denote that words are to be expressed; if to the second, that figures; if to the third, that the figures cease ; and that the intelligence is carried on in words. When figures are to be expressed, the alternate apertures from the left are taken in their order, to denote from 1 to 10 inclusively; the second from the right denotes 100; the fifth 1000. This order, and these intervals, are taken, to pre- yent any confusion in so peculiarly important an article of the intelligence to be conveyed. - A B | D F. F G. | 0 O () 0 000 0 00 00 0 || 000 000 || 0 00 0 O I K L M N o 00 () 0 0 () 00 0 000 00 || 0 0 (30 00 0 O * ()0 P R S T U Y * | 00 () () 0 0 00 0 0 00 0 () 00 0 0 () 0 | 0 00 O Perhaps, however, few of the telegraphs hitmerto offered to the public exceed the preceding, either in its simplicity, cheap- ness, or facility in working; and it might, perhaps, with a few trifling additions, be made exceedingly distinct. It is thus described in the Repertory of Arts qud Manufactures. For a noc- turnal telegraph let there be four large patent reflectors, lying on the same plane, parallel to the horizon, placed on the top of 1 1 U. 994 ..T.E L T E L DICTIONARY OF MECHANICAL SCIENCE. an observatory. , Let each of these reflectors be capable, by means of two winches, either of elevation or depression to a certain degree. By elevating or depressing one or two of the reflectors, eighteen very distinct arrangements may be produced, as the preceding scheme will explain. For the sake of example, the above arrangements are made to answer to the most necessary letters of the alphabet; but alterations may be made at will, and a greater number of changes produced, without any addition to the reflectors. In the first observatory there need only be a set of single reflectors; but in the other, each reflector should be double, so as to face both the preceding and subsequent observatory; and each observatory should be furnished with two telescopes. The pro- per diameter of the reflectors and their distance from each other will be ascertained by experience; and it must be observed, that each reflector, after every arrangement, must be restored to its place. nothing more is necessary, than to insert in the place of the re- flectors, gilt balls, or any other conspicuous bodies.—Since these inventions were made public, telegraphs have been brought to so great a degree of perfection, that they now convey informa- tion speedily and distinctly, and are so much simplified that they can be constructed and maintained at little expense. The advantages, too, which result from their use, are almost in- conceivable. Not to speak of the speed with which information is communicated and orders given in time of war, by means of them, the whole kingdom could be prepared in an instant to oppose an invading enemy. A telegraph might also be used by To convert this machine into a diurnal telegraph, commercial men to convey a commission cheaper and speedier . than an express can travel. f An establishment of telegraphs might be made like that of the post; and instead of being an expense, it would produce a revenue. Something of this kind was about ten years ago set up, to facilitate the intercourse be- tween Norwich and Yarmouth.--Dr. Gregory's Mechanics. TELESCOPE. Under the article Optics, the character, use, and power of this valuable instrument, have been introduced to the reader's notice. We shall now advert to two remarkably con- structed telescopes, that of Fraunhofer, and that of Dollond. The great discovery of a method of making flint glass in large pieces, and perfectly pure and free from striae, which was made by the late M. Guinand, may be considered as forming an era in the history of the achromatic telescope. By means of this glass, M. Fraunhofer, the director of the Optical Institute or manufactory at Benedictbauern, near Munich, has con- structed achromatic telescopes far superior to any that have hitherto been made; and we have been assured, that this emi- ment artist can now make achromatic object-glasses with an aperture of eighteen inches. But it is not merely in the optical part of the instrument that M. Fraunhofer has been successful. His various improvements on the apparatus which accompanies the telescope, and his ingenious micrometers for measuring angles of all kinds in the heavens, have repeived the sanction of some of the most eminent practical astronomers in Europe, and are now considered as constituting an instrument of incalcu- lable value for general astronomical observations. In this splendid telescope, made for the observatory of Dorpat, the hour- circle is divided by two verniers into four seconds of time, and the declination circle into ten seconds. The equatorial axis is put in motion by a clock having two sets of wheel-work, so that the telescope follows by itself the diurnal motion of the stars. But it may also be turned freely by the hand in every direction, or by means of an endless screw. The friction of the equatorial axis is diminished by friction rollers, so that the telescope, though its weight was about thirty-six quintals of Bavaria, could be moved by the pressure of a single finger. The object. glass is thirteen and one-third feet (Pied de Ro de Paris) in focal length, and its aperture is nine inches. It has eight astronomical eye-pieces, beside the following micrometers:– 1. A repeating line micrometer, with a circle of position, whose two verniers give a single minute. This micrometer is furnished with a mechanism for illuminating the lines, the field remaining obscure, so that these lines appear to be luminous stripes on a darkground. These lines are cut upon glass with a diamond point. As these lines appear like so many silver threads suspended in the heavens, the transits of the smallest stars across them may be observed. 2. Two micrometers, each of which consists of two suspended in the field of the telescope. any land, objects. free rings. 3. Two micrometers with one free ring. In all these micrometers, the rings, which are accurately turned out of brass, are fixed upon plates of glass, so that they seem to be By observing the im- mersions and emersions of the stars at the inner and outer cir- cumferences of the rings, the differences of right ascension and declination of two stars are determined. 4. A micrometer of several concentric rings, which may be illuminated in the dark field. This micrometer has four eye-glasses. 5. An achroma- tic finder, of thirty inches in focal length, and twenty-nine of aperture. An instrument for correcting the axis of the great object-glass.-The price of the telescope now described is about 8000 Prussian dollars, or nearly £1300 sterling. The total weight of the whole package is thirty-eight quintals. An achro- matic telescope with an object-glass eighteen feet in focal length, and with an aperture of twelve inches, and furnished with eye-glasses, micrometers, and parallactic stand, like the one now described, amounts to about £2720 sterling. Mr Fraunhofer engages likewise to construct these instruments with object-glass eighteen inches in diameter: and, as the price increases nearly as the cube, of the diameter, an instrument of this kind will cost about £9200 sterling. Dollond's Achromatic Telescope.—Fig. 5, No. 1, in the plate, represents the telescope, supported in the centre of gravity, with its rack-work motions, and mounted on its mahogany stand, the three legs of which are made to close up together by means of the brass frame a a a, which is composed of three bars con- nected together in the centre piece by three joints, and also to the three legs of the mahogany stand by three other joints, so that the three bars of this frame may lie close against the insides of the legs of the mahogany stand, when they are pressed toge- ther for convenience of carriage. The brass pin, under the rack-work, is made to move round in the brass socket b, and may be tightened by means of the finger-screw d, when the telescope is directed nearly to the object intended to be observ - ed. This socket turns on two centres, by which means it may be set perpendicular to the horizon, or to any angle required in respect to the horizon; the angle may be ascertained by the divided arc, and then made fast by the screw e. If this socket be set to the latitude of the place at which the telescope is used, and the plane of this arc be turned on the top of the mahogany stand, so as to be in the plane of the meridian, the socket b being fixed to the inclination of the pole of the earth, the tele- scope, when turned in this socket, will have an equatorial mo- tion, which is always very convenient in making astronomical observations. - - No. 2, in the plate, represents a stand to be used on a table, which may be more convenient for many situations than the large mahogany stand. The telescope, with its rack-work, may be applied to either of the two stands, as occasion may require, the sockets on the top of both being made exactly of the same size. The sliding rods may be applied to the feet of the brass stand, so that the telescope may be used with the same advan- tages on one as on the other. The tube A A may be made either of brass or mahogany, of three and half feet long. The achromatic object-glass of three and half feet focal distance has an aperture of two inches and three quarters. The larger size is with a tube five feet long, and has an achromatic object-glass of three inches and one quarter aperture. The eye tube, as re- presented by B, contains four eye-glasses to be used for day, or * There are three eye tubes, as C, which have two glasses in each to be used for astronomical purposes. These eye tubes all screw into the short brass tube at D. By turning the button or milled head at f, this tube is moved out of the larger so as to adjust the eye-glasses to the proper distance from the object-glass, to render the object distinct to any sight with any of the different eye tubes. The magnifying power of the three and half feet telescope with the eye tube for land objects is forty-five times, and of the five feet, for land objects, sixty- five times; with those for astronomical purposes, with the three and half feet the magnifying powers are eighty, one hundred and thirty, and one hundred and eighty; and for the five feet one hundred and ten, one hundred and ninety, and two hundred and fifty-times. Stained glasses, as g, are applied to all the different eye tubes, to guard the eye in observing the spots on the sun. These are to be taken off when the eye tubes are used T E M T E N DICTION ATRY | OF MECHANICAL SCIENCE. 995 for other purposes. The rack-work is intended to move the telescope in any direction required, and is worked by means of the two. handles at h. When the direction of the tube is re- quired to be considerably altered, the worm screws which act against the arc, and the circle must be discharged; then the screw d, being loosened, the pin of the rack-work will move easily round in the socket d. * For the more readily finding or directing the telescope to any object, particularly astronomical objects, there is a small tube or telescope, called the finder, fixed near the eye-end of the large telescope. At the focus of the object-glass of this finder there are two wires, which intersect each other in the axis of the tube, and as the magnifying power is only about six times, the real field of view is very large; therefore any object will be readily found within it, which being brought to the intersection of the wires, it will then be within the field of the telescope.—In viewing astronomical objects, (and particularly when the great- est magnifying powers are applied) it is very necessary to render the telescope as steady as possible ; for that purpose there are two sets of brass sliding rods, i i, as represented in the plate. These rods connect the eye-end of the telescope with two of the legs of the stand, by which any vibration of the tube, that might be occasioned by the motion of the air, or otherwise, will be prevented, and the telescope rendered suffi- ciently steady for using the greatest powers. These sliding rods move within one another, with so much ease as to admit of the rack-work being used in the same manner as if they were not applied. Herschel’s Telescope.—This wonderful instrument was begun at Clayhill in 1785, and afterwards, with all its appa- tus, removed to Slough, near Windsor, where it was completed sunder the fostering patronage of royal munificence. The foun- dation on which the frame-work is erected, consists of two concentric circles of brickwork, so constructed, that the machi- nery may be turned so as to bring the point of the tube against any part of the heavens. The whole fabric is supported on twelve rollers, of which six are seen (II II) in the drawing. On each side of the elevated end of the tube is a double ladder, and at the opposite extremity is another. Several other smaller ones are seen in different parts, but their uses are too obvious to need either reference or description. The trans- verse beam H. H., which is stretched horizontally over the crossings of the ladders, is bolted to them, and receives the hooks of different pulleys G. G., as seen in the drawing. The ropes connected with these pulleys are moved by machinery, near the bottom. Below the mouth of the large tube is a gallery; C B, so constructed as to be elevated or depressed accord- ing to the situation of the tube. This furnishes gratification to the spectator, and enables the astronomer who views the heavens, to have access to the extremity of the tube whenever his presence may be required. The cabin D, of which the window is visible, affords shelter to those Within, who, through ‘the telescope, watch the motions of the heavenly bodies. The smaller cabin under the tube, is connected with the apparatus. —The tube of the telescope, which is 32 feet 4 inches long, and 4 feet 10 inches in diameter, is made entirely of iron, it having been ascertained that one of wood would exceed the iron one in weight by at least 3000lb. The sheets were first put toge- ther by a kind of seaming that required no rivets, and when the sides of the iron platform were cut straight, it was lifted into a hollow gutter, and then brought gradually into a cylin- drical form. Within the tube various hoops are fixed, some of which are connected by longitudinal bars of iron that are attached to the two ends of the tube. These are introduced, to brace the sheets, and keep the shape perfect, when the pulleys are applied to give the necessary elevation at the upper end, and that the speculum might be kept secure in its bed at the lower extremity. Its proportionate degrees of strength have been calculated with great care, so that at A no depression takes place. The lower end of the tube, which the cabin D renders invisible, is firmly supported on rollers that move forward or backward by the rackwork seen at E. The large speculum is enclosed in a strong iron ring, braced across with bars of iron, while an enclosure of iron and tin sheets makes a ease for it. When necessity requires, it is lifted by three iron handles attached to the sides of the ring, and is taken from moveable crane that runs on a and returned to its place by a carriage. See Optics. TELESCOPIUM, the Telescope, situated south of the Centaur Sagittarius, and contains nine small stars, one of which is of the fourth magnitude, the rest being less in size. TELEscopium HERscheli. Herschel's telescope is a new as- terism, which has been inserted in honour of the astronomer of that name.—Boundaries and Contents: N. and E. by Lynx, E. and S, by the Twins, and W. by Auriga; right ascension 95°, declination 40° N. About 17 stars have been assigned to this constellation, from the 5th magnitude to the 8th. TELLER, an officer of the exchequer, in ancient records call- ed tallier; there are four of these officers, whose duty is to receive all sums due to the king, and to give the clerk of the pells a bill to charge him there with. TELL-TALE, on ship-board, a small piece of wood, tra- versing in a groove across the front of the poop deck, and which, by communicating with a small barrel on the axis of the steering wheel, indicates the situation of the helm. TEMPERATURE, in general, denotes that degree of free caloric which a body appears to possess when compared with other bodies. Sir Humphrey Davy defines temperature to be “ the power bodies possess of communicating or receiving heat, or the energy of repulsion.” This definition, however, seems to have nothing but the celebrity of his name to recom- mend it. - TEMPERING, of steel and iron, the rendering of them either more compact and hard, or soft and pliant, according as the different uses for which they are wanted may require. TEMPLARS, or TEMPLERs, a religious order instituted at Jerusalem, about the year 1118. Some religious gentlemen put themselves under the government of the patriarch of Jerusalem, renounced property, made the vow of celibacy and obedience, and lived like canons regular. King Baldwin assigned them an apartment in his palace. They had likewise lands given them by the king, the patriarch, and the nobility, for their mainte- nance. They took the name of knights templars, because their first house stood near the temple dedicated to our Saviour at Jerusalem. This order having performed many great exploits against the infidels, became rich and powerful all over Europe; but the knights abusing their wealth and credit, fell into great disorders and irregularities. Many crimes and enormities being alleged against them, they were prosecuted in France, Italy, and Spain; and at last the pope, by his bull of the 22d of May, 1312, given in the council of Vienna, pronounced the extinction of the order of Templars, and united their estates to the order of St. John of Jerusalem. - - TEMPLE, a public building erected in honour of some deity, either true or false, and in which people meet to pay religious worship to the same. • TENACITY, a term applied to metals, by which is meant the power that a metallic wire of a given diameter has of resisting, without breaking, the action of a weight suspended from its ex- tremity. - TENANT, signifies one who holds or possesses lands or tenements by any kind of right, either in fee, for life, years, or at will. TENDER, in Law, is an offer to pay a debt or perform a duty. This is is often pleaded in an action as a bar to the plaintiff’s recovery; and where the money demanded by the plaintiff has been tendered or offered to him before the commencement of the suit, and he has refused to accept it, the plaintiff is barred of his action and costs. - Ten DER, a small vessel employed to attend a larger one, to supply her with stores, to carry intelligence, &c. Vessels appointed to receive volunteers and impressed men, and to . carry them to receiving ships, &c. are also called tenders. TENDING, the movement by which a ship turns or swings round, when at single anchor, or moored by the head, in a tide- way, at every change of tide. TENDONS, are white, firm, and tenacious parts, continuous to the muscles, and usually forming their extremities. TENEMENT, in its original, proper, and legal sense, signifies every thing that may be holden, provided it is of a permanent * whether it is of a substantial or unsubstantial and ideal ‘IIl Cls - - * - 996 * T E S T E R DICTIONARY OF MECHANICAL SCIENCE. TENNIS, a play at which a ball is driven by a racket. TENON, in Building, &c. the square end of a piece of wood, or metal, diminished by one-third of its thickness, to be receiv- ed into a hole in another place, called a mortise, for joining or fastening the two together: TENSE, time, in Grammar, an inflection of verbs, whereby they are made to signify or distinguish the circumstance of time in what they affirm. TENSION, the state of a thing stretched. TENT, in Surgery, a roll of lint worked into the shape of a mail with a broad flat head. TENTER, a railing used in cloth manufacture, to stretch out the pieces of cloth, stuff, &c. or only to make them even, and set them square. It is usually about four feet and a half high, and for length exceeds that of the longest piece of cloth. It consists of several long pieces of wood, placed so that the lower cross-piece of wood may be raised or lowered, as is found requisite, to be fixed at any height by means of pins. Along the pieces, both the upper and under one, are hooked nails, called tenter-hooks, driven in from space to space. - TENURE, the manner whereby lands or tenements are holden, or the service that the tenant owes to his lord. TEREDO, in Natural History, the ship-worm, a genus of the vermes testacea class and order. There are three species. The shell of this worm is very thin, cylindrical, and smooth; found on the sides and bottoms of ships, and the stoutest oak pales which have remained some time under water: it was imported from India. The destruction which these worms effect under water is almost equal to that of the termes, or white ant, on land. The shell is more or less twisted, rather obtuse at the lip, and from four to six inches long. They will appear, on a very little consideration, to be the most important beings in the great chain of creation, and a pleasing demonstration of the infinitely wise and gracious power which formed and still pre- serves the whole in such wonderful order and beauty; for if it was not for the rapacity of these and such animals, tropi- cal rivers, and indeed the ocean itself, would be choked with the bodies of trees annually carried down by the rapid tor- rents, as many of them would last for ages, and probably be productive of evils, of which happily we cannot in the present harmonious state of things form any idea; whereas now, being consumed by these animals, they are more easily broken in pieces by the waves; and the fragments which are devoured become specifically lighter, and are consequently more readily and more effectually thrown on shore, where the sun, wind, insects, and various other instruments, speedily promote their entire dissolution. TERM, in Geometry, is the extreme of any magnitude, or tha which bounds or limits its extent. . TERMS, are those spaces of time wherein the courts of jus- tice are open for all that complain of wrongs or injuries, and seek their rights by course of law or action, in order to their re- dress; and during which the courts in Westminster hall sit and give judgments, &c. but the high court of parliament, the chan- cery, and inferior courts, do not observe the terms; only the oourt of King's Bench, Common Pleas, and Exchequer, the highest courts at common law. Of these terms there are four in every year: viz. Hilary term, which begins the 23d of Janu- ary, and ends the 12th of February, unless on Sundays, and the day after ; Easter term, which begins the Wednesday fortnight after Easter-day, and ends the Monday next after Ascension-day; Trinity term, which begins on the Friday after Trinity Sunday, and ends the Wednesday-fortnight after; and Michaelmas term, which begins the 6th and ends the 28th of November. - TERMS, Irish, are the same as those of London, except that at Michaelmas, which commences October 13, and adjourns to the beginning of November. TERMs, Oaford. Hilary or Lent term begins on January 14, and ends on the Saturday before Palm Sunday. Easter term begins the tenth day after Easter, and ends the Thursday be- fore Whit-Sunday. Trinity term begins the Wednesday after Trinity Sunday, and ends after the act, sooner or later, as the vice chancellor and convocation please. Michaelmas term begins on Oct. 10, and ends Dec. 17. TERMS, Cambridge. Lent term begins on Jan. 13, and ends the Friday before Palm Sunday. Easter term begins the Wed- I nesday after Easter week, and ends the week before Whit. Sunday. Trinity term begins the Wednesday after Trinity Sunday, and ends the Friday after the commencement, Mi- chaelmas term begins Oct. 10, and ends Dec. 16. TERMs Scottish. In Scotland, Candlemas term begins Jan. 23, and ends Feb. 12. Whitsuntide term begins May 25, and ends June 15. Lammas term begins July 30, and ends August 8. Martinmas term begins Nov. 3, and ends Nov. 21. TERMES, or ANT, in Natural History, a genus of insects of the order aptera. The white ant is given in the Philosophical Transactions, of which we shall notice a few particulars. These insects are inhabitants of East India, Africa, and South Ameri- ca. They build pyramidal structures ten or twelve feet in height, and divided into appropriate apartments, magazines for pro- visions, arched chambers, and galleries of communication. These are so firmly cemented, that they easily bear four men to stand upon them, and in the plains of Senegal appear like the villages of the antives. With such wonderful dexterity and rapidity they destroy food, furniture, books, clothes, and tim- ber of whatever magnitude, leaving a mere thin surface, that in a few hours a large beam will be eaten to a mere shell not thicker than writing paper. These only are the labourers who build the structures, procure provisions for the males and females, and take care of the eggs ; they are the most nume- rous. Another class, called pupa, are larger, about half an inch long, with a very large ovate polished testaceous head. These never work, but act as superintendants over the labourers, or as guards to defend their habitations from intrusion and vio- lence. When a breach is made in the dwelling, they rush forward, and defend the entrance with great ferocity; some of them beat- ing with their mandibles against any hard substance, as a sig- nal to the other guards, or as an encouragement to the labour- ers; they then retire, and are succeeded by the labourers, each with its burden of tempered mortar in its mouth ; these diligent- ly set about to repair whatever injury has been sustained. One of these attend every six or eight hundred labourers which are building a wall, taking no active part itself, but frequently mak- ing the noise above mentioned, which is constantly answered by a loud hiss from all the labourers, which at this signal evi- dently redouble their diligence. TERRIER, a book or roll, wherein the several lands, either of a private person, or of a town, college, church, &c. are de- scribed. It should contain the number of acres, and the site, boundaries, tenants’ names, &c. of each piece or parcel. TESSELLATED PAVEMENTS, those of rich mosiac work, made of curious square marbles, bricks, or tiles, called tesselae from their resembling dice. - Test Act. A statute 25 Car. II. cap. 2, which requires all officers, both civil and military, to take the oaths and test, viz. the sacrament, according to the rights and ceremonies of the church of England. Various ineffectual attempts have been made by the isseåters to obtain the repeal of this act, which is evidently offensive to the genuine principles of civil and reli- gious liberty. TESTACEA, in the Linnaean system of natural history, the third order of vermes. This order comprehends all shell-fish, ar- ranged by Linnaeus under thirty-six genera. Shell-fish are ani- mals with a short body, covered by or enclosed in a firm, hard, and stony habitation, composed according to their three sepa- rate orders. - TESTAMENT, in Law, a solemn and authentic act, whereby a person declares his will, as to the disposal of his estate, effects, burial, &c. TESTUDO, the Tortoise, in Natural History, a genus of am- phibia, of the order reptiles. These animals feed on sea-weeds or on worms, are extremely prolific; but in the state of eggs, and while very young, are the prey of various animals. Their move- ments are slow ; they are capable of being tamed, and will in that state eat almost any thing presented to them. They ex- ist long in such air as would be destructive to other animals of the same size, and have such tenaciousness of life, that it is stated that they will exhibit convulsive movements for several days after their bodies have been opened, and even after their heads have been cut off. In cold latitudes the land tortoise is torpid during the winter. There are thirty-five species, of which we shall notice the following.—The common tortoise. The weight * T. E. T T E U 997 DICTIONARY OF MECHANICAL SCIENCE. of this animal is three pounds, and the length of its shell about seven inches. It abounds in the countries surrounding the Mediterranean, and particularly in Greece, where the inhabitants not only eat its flesh and eggs, but frequently swallow its warm blood. In September or October it conceals itself, remaining torpid till February, when it re-appears. In June it lays its eggs in holes exposed to the full beams of the sun, by which they are matured. The males will frequently engage in severe conflicts, and strike their head against each other with great violence, and very loud sounds. Tortoises attain most extraordinary longevity, and one was ascertained to have lived in the gardens of Lambeth to the age of nearly one hundred and twenty years. Its shell is preserved in the archiepiscopal palace. So reluctant is the vital principle to quit these animals, that Shaw informs us from Redi, one of them lived for six months after all its brains were taken out, moving its limbs and walking as before. Another lived twenty-three days after its head was cut off, and the head itself opened and closed its jaws for a quarter of an hour after its separation from the body. It may not only be tamed, but has in several instances exhi- bited proof in that state of considerable sagacity, in distinguish- ing its benefactors, and of grateful attachment in return for their kindness, notwithstanding its general sluggishness and torpor. It will answer the purpose of a barometer, and uniformly indi- cates the fall of rain before night, when it takes its food with great rapidity, and walks with a sort of mincing and elate step. It appears to dislike rain with extreme aversion, and is dis- comfited and driven back only by a few and scarcely perceiv- able drops.—The mud tortoise, is common both in Europe and Asia, and particularly in France, where it is much used for food. It is seven inches long; lays its eggs on the ground, though an aquatic animal; walks quicker than the land tortoise ; and is often kept in gardens, to clear them from snails and various wingless insects. In fish-ponds it is very destructive, biting the fishes, and, when they are exhausted by the loss of blood, drag- ging them to the bottom and devouring them.--The fierce tor- toise, is found in several parts of North America, and is eighteen inches long. It is rapid and vigorous in its movements, and will spring on its enemy with great elasticity and violence. Its flesh is thought extremely good. It is found in the muddy parts of rivers, concealing itself among the weeds. It will also dart with great celerity on birds.—The sea tortoises, or turtles, are distinguished from the former, by having very large and long feet in the shape of fins, the claws of some of the toes not being visible but enclosed. The common green turtle is not unfre- quently five feet long, and of the weight of 500 pounds; and is denominated green from the shade of that colour assumed by the fat, when the animal is in its perfect state. In the West Indies it has been long in the highest estimation for the table, and within sixty or seventy years it has gradually been advanc- ing in reputation in this country, for food, and is at present con- sidered as furnishing the highest gratification of epicurism. It is imported into England in vast numbers. It feeds on sea grass, called turtle grass. It is taken sometimes after being Watched to its haunts; and being thrown on its back, is unable to rise again on its feet: sometimes it is struck in the water with a long staff armed with iron at the end. The markets of the West Indies are supplied with the flesh of these animals, as those of Europe are with mutton and beef; and before they were much sought as articles for exportation, forty sloops were em- ployed by the inhabitants of Port Royal in catching them. They are seldom seen on land but at the season of laying their eggs, which they do at several times, after intervals of fourteen days. They are occasionally found, probably in consequence of tem- pests, on the coasts of Europe. The imbricated turtle, or hawks- bill, is so called from its shells lapping one over another, like tiles on the roof of a house. It is about three feet long; is found in the seas both of Asia and America, and sometimes also in the Mediterranean; and is said to have been seen even of 600 pounds weight. Its flesh is of no estimation; but its lamina are manufactured into the elegant material known by the name of tortoise-shell, which has been applied by human ingenuity, to Innumerable purposes both of use and ornament. The thick- mess of the plate varies in reference to the age and size of the turtle....Those of a very young one are of no value. A large one will upply ten pounds' weight of valuable scales, which being softened by heat, and lapped over each other by means of pressure, become effectually united, so as to constitute one piece of considerable extent, and without any perceivable trace of their separation. This article was well known to the Greeks and Romans, and was an important materal of luxury and com- merce. Various articles of furniture, and even beds, were inlaid with it. The Egyptians exported large cargoes of it to Rome for these purposes, and in China, as well as Europe, it is at present in very high demand for elegant and ornamental manu- factures. TESTUDo, in the Military Art of the ancients, was a kind of cover or screen which the soldiers, e. gr. a whole company, made themselves of their bucklers, by holding them up over their heads, and standing close to each other. This expedient served to shelter them from darts, stones, &c. thrown upon them, especially those thrown from above, when they went to the assault. - * * TESTUDo, was also a kind of large wooden tower which moved on several wheels, and was covered with bullocks' hides, serv- ing to shelter the soldiers when they approached the walls to mine them, or to batter them with rams. TETANUS, in Surgery, a locked jaw. TETRAEDRON, or Tet RAH ed Ron, in Geometry, is one of the five Platonic or regular bodies or solids, comprehended under four equilateral and equal triangles. Or, it is a triangular pyramid of four equal and equilateral faces. TETRAGON, in Geometry, a quadrangle, or a figure with four angles. - TETRANDRIA, the fourth class in Linnaeus's sexual system. TETRAO, in Natural History, a genus of birds of the order gallinae. Birds of this genus, which according to Gomelin com- prehends the grouse, the partridge, and the quail, follow the dam immediately on being hatched, and before the shell is wholly detached from them ; their bill is strong and convex, and their flesh and eggs form an exquisite repast. There are seventy-three species, of which the following are best deserving of notice.—The cock of the wood, is of the size of a turkey, and is found from Russia to Italy, preferring the elevated and mountainous parts of temperate countries, as it delights in a cold temperature. Its eggs are deposited on moss, and when- ever left by the female, which is unassisted in the process of incubation, are covered over with leaves. The males and females live separate, except during the months of February and March. Their food consists of various plants and grains, and buds of trees. The seeds of the pine and fir they are parti- cularly fond of.-The black grouse, is larger than a common fowl, and abounds in the British islands, particularly in the northern districts. The birds of this species, and of the last, do not pair like other birds, and the male is generally seen with several females in his train, They subsist on seeds and herb- age, and are particularly fond of the seeds of the birch and Siberian poplar.—The ptarmigan grouse, is fourteen inches long, and inhabits the north of Europe. It is not uncommon in the Highlands and the Hebrides, and is sometimes found in Cumberland. These birds subsist on seeds, fruits, and berries, and are silly and inadvertent to danger.—The common partridge, is thirteen inches long, and abounds in the temperate regions of Europe; it is unable to sustain rigorous cold or intense heat. See QUAIL. . - - TETRAPLA, a Bible disposed by Origen under four columns, in each of which was a different Greek version, namely, that of Symmachus, of Aquila, of the Seventy, and of Theodotian. TEUTONIC ORDER, a military order of knights, established towards the close of the twelfth century, and thus called as con- sisting chiefly of Germans or Teutons. The ºrigin, &c. of the Teutonic order is said to be this ; the Christians under Guy of Lusignan, laying siege to Acre, a city of Syria, on the borders of the Holy Land, some Germans of Bremen and Lubeck, touch- ed with compassion for the sick and wounded of the army, who wanted common necessaries, set on foot a kind of hospital un- der a tent, which they made of a ship’s sail, and here betook themselves to a charitable attendance on them. This excited a thought of establishing a third military order, in imitation of the Templars and Hospitallers. The design was approved of by the patriarch of Jerusalem, the archbishop and bishops of . the neighbouring places, the king of Jerusalem, the masters of 11 X 998 T H E T H E DICTIONARY OF MECHANICAL SCIENCE. the temple and hospital, and the German lords and prelates then in the Holy Land, and Pope Calixtus III. conſirmed it by his bull, and the new order was called the Order of Teutonic Knights of the House of St. Mary at Jerusalem. The pope grant- ed them all the privileges of the Templars and Hospitallers of St. John, excepting that they were to be subject to the patri- archs and other prelates, and that they should pay tithes of what they possessed. - TEXT, a relative term, contradistinguished to gloss or com- mentary, and signifying an original discourse, exclusive of any note or interpretation. This word is particularly used for a certain passage of scripture chosen by a preacher to be the sub- ject of a sermon. - THALLITE, a stone found in the fissures of mountains in Dauphiny, and on Chamouni in the Alps. It is sometimes amorphous, and sometimes crystallized. THATCH, prepared straw or reed, laid on the top of ricks, stacks, or houses, to keep out the wet. THEATRE, a public edifice for the exhibition of scenic spectacles and shows, to amuse the people, and also a place for dramatic representations. In Surgery, it is the room in which anatomical dissections are carried on. THEFT, in Law, an unlawful felonious taking away another man’s moveable and personal goods, against the owner’s will, with intent to steal them. It is divided into theft or larceny, properly so called, and petit theft, or petit larceny ; the former whereof is of goods above the value of 12d. and is deemed felo- my ; the other, which is of goods under that value, is not felony. THEFTBOTE, the receiving a man’s goods again from a thief, or other amends by way of composition, and to prevent prosecution, that the felon may escape unpunished; the punish- ment whereof is fine and imprisonment. . THEME, a subject or topic on which to write or compose. THEODOLITE, a mathematical instrument much used in surveying, for the taking of angles, distances, &c. THEOGONY, the science which treats of the primitive, chaotic, or elementary state of things. . THEOLOGY, the science which instructs mankind in the knowledge of God and divine things; or th; t which has God, and what he has revealed, for its object. THEOREM, a proposition which terminates in theory, and which considers the properties of things already made or done. Gr, theorem is a speculative proposition deduced from several definitions compared together. THEORY, a doctrine which terminates in speculation, with- out any view to the practice or application of it. THERMOMETER, an instrument for ascertaining the tem- perature, that is, for measuring the degree of heat or cold, in any body. The thermometer was invented about the beginning of the 15th century ; but, like many other useful inventions, it has been found impossible to ascertain to whom the honour of it belongs. Fahrenheit's thermometer consists of a slender cylindrical tube, and a small longitudinal bulb. To the side of the tube is annexed a scale, which Fahrenheit divided into 600 parts, beginning with that of the severe cold which he had observed in Iceland in 1709, or that produced by surrounding the bulb of the thermometer with a mixture of snow or beaten ice, and sal ammoniac or sea salt. This he apprehended to be the greatest degree of cold, and accordingly he marked it, as the beginning of his scale, with 0; the point at which mercury begins to boil, he conceived to shew the greatest degree of heat, and this he made the limit of his scale. The distance between these two points he divided into 600 equal parts or degrees; and by trials he found that the mercury stood at 32 of these divisions when water just begins to freeze, or snow or ice just begins to thaw ; it was therefore called the degree of the freez- ing point. When the tube was immersed in boiling water, the mercury rose to 212, which therefore is the boiling point, and is just 180 degrees above the former, or freezing point. But the present method of making the scale of these thermometers, which is the sort in most common use, is first to immerge the bulb of the thermometer in ice or snow just beginning to thaw, and mark with 32 the place where the mercury stands; then immerge it in boiling water, and again mark the place where the mercury stands in the tube with the number 212, exceeding the former by 180; dividing therefore the intermediate space into - | 180 equal parts, will give the scale of the thermometer; which may afterwards be continued upwards and downwards at plea- sure. Other themometers of a similar construction have been accommodated to common use, having but a portion of the above scale. They have been made of a small size and portable form, and adapted with appendages to particular purposes; and the tube, with its annexed scale, has often been enclosed in another thicker glass tube, also hermetically sealed, to preserve the thermometer from injury. And all these are called Fahren- heit's thermometers. - The thermometer at present used in France is called Reau- mur's; but it is very different from the one originally invented by Reaumur in 1730, and described in the Memoirs of the Aca- demy of Sciences. The one invented by Reaumur was filled with spirit of wine; and though its scale was divided by the author into 80 parts, of which 0 was the freezing point, and 80 the boiling-water point, yet in fact 80 was only the boiling point of the spirit of wine that he employed, which, as Dr. Martine computes, corresponded with 180 of Fahrenheit. But the ther- mometer now in use in France is filled with mercury; and the boiling-water point, which is at 80, corresponds with the 212th degree of Fahrenheit. The scale indeed commences at the freezing point, as the old one did. The new thermometer ought more properly to be called De Luc's thermometer, for it was first made by De Luc ; and is in fact as different from Reaumur’s as it is from Sir Isaac Newton's. When De Luc had fixed the scale, and finished an account of it, he shewed the manuscript to M. De la Condamine. Condamine advised him to change the number 80; remarking, that such was the inattention of philosophers, that they would probably confound it with Reau- mur's. De Luc's modesty, as well as a predilection for the number 80, founded as he thought on philosophical reasons, made him decline following this advice. But he found by expe- rience that the prediction of Condamine was too well founded. The thermometer of Celsius, which is used in Sweden, has a scale of 100 degrees from the freezing to the boiling-water point. This is, in fact, the centigrade thermometer. These are the principal thermometers now used in Europe; and the tem- perature indicated by any of them may be reduced into the cor- responding degrees on any of the others, by means of the following simple theorems; in which R signifies the degrees on the scale of Reaumur, F those of Fahrenheit, and S those of the Swedish thermometer. 1. To convert the degrees of Reaumur into those of Fahren- 9 º + 32 = F. 2. To convert the degrees of Fahren- heit; (F - 32) × 4 heit to those of Reaumur; 3. To con- * R. *= , =s: gº vert the Swedish degrees into those of Fahrenheit; 32= F. 4. To convert Fahrenheit's into Swedish ; g-ºxº = S. 5. To convert Swedish degrees into those of Reaumur; s: = R. 6. To convert Reaumur's degrees into Swedish; Rºx 5. 4 - To such readers as are unacquainted with the algebraic ex- pression of arithmetical formulae, it will be sufficient to express one or two of these in words, to explain their use;—1. Multiply the degree of Reaumur by 9, divide the product by 4, and to the quotient add 32; the sum expresses the degree on the scale of Fahrenheit. 2. From the degree of Fahrenheit subtract 32, multiply the remainder by 4, and divide the product by 9, the quotient is the degree according to the scale of Reaumur, &c.— As in meteorological observations it is necessary to attend to the greatest rise and fall of the thermometer, attempts have been made to construct a thermometer which might register the greatest degree of heat, or greatest degree of cold, which took place during the absence of the observer.—The following. is properly a spirit thermometer, though mercury is em- ployed in it for the purpose of supporting a certain index; a 5 T H E T H E 999 DICTIONARY OF MECHANICAL SCIENCE. (fig, 1, is) a tube of thin glass, about sixteen inches long, and # of an inch in diameter; c defy his a smaller tube, £21. with the inner diameter about 35th join- fit ed to a larger at the upper end b, and º h Fig.2. bent down first on the left side, and then, after descending two inches be-, low a b, upwards again on the right, in the several directions c de, fº h, paral- , iſ lel to, and one inch distant from it. At the end of the same tube, at h, || the inner diameter is enlarged to ||| half an inch from h to i, which is | two inches in length. This glass is |'9 filled with highly rectified spirit of d wine to within half an inch of the end i, excepting that part of the small tube from d to g which is filled with mercury. From a view of the instru- ment, it will be readily conceived that when the spirit in the large tube is ex- £2. panded by heat, the mercury in the small tube on the left side will be press- ed down, and cause that on the right side to rise; on the contrary, when by cold, the reverse will happen. Fahrenheit's scale, which be- gins with 0 at the top of the left side, has the degrees numbered downwards, while that at the right side, beginning with 0 at the bottom, ascends. The divisions are ascertained by placing the thermometer with a good standard mercurial one in water, gradually heating or cooling, and marking the divisions of the new scale at every five degrees. The divisions below the freez- ing point are taken by means of a mixture of sea-salt and ice, as described by Nollet, De Luc, and others. In order to shew how high the mercury has risen in the observer's absence, there is placed within the small tube of the thermometer, above the surface of the mercury on either side, immersed in the spirit of wine, a small index, so fitted as to pass up and down as occa- sion may require. One of these indices is represented in fig. 2; a is a small glass tube, three-quarters of an inch long, her- metically sealed at each end, enclosing a piece of steel wire nearly of the same length; at each end, c d, is fixed a short piece of a tube of black glass, of such a diameter as to pass freely up and down within the small tube of the thermometer. The lower end floating on the surface of the mercury, is carried up with it when it rises, while the piece at the upper end, being of the same diameter, keeps the body of the index parallel to the sides of the thermometrical tube. From the upper end of the body of the index at c is drawn a spring of glass to the fine- ness of a hair, about four-fifths of an inch in length, which be- ing set a little oblique, presses lightly against the surface of the tube, and prevents the index from following the mercury € $ sº f when it descends, or being moved by the spirit passing up and | down, or by any sudden motion given to the instrument; but at the same time the pressure is so adjusted as to permit this index to be readily carried up by the surface of the rising mer- cury, and downwards whenever the instrument is rectified for observation. The index, by not returning with the mercury when it descends, shews distinctly and accurately how high the mercury has risen, and consequently what degree of cold or heat has happened. To prevent the spirit from evaporating, the tube at the end i is closely sealed. The daily rectification of this instrument is performed by applying a small magnet to that part of the tube against which the index rests; by the action of which the included piece of steel wire, and consequently the index, is easily brought down to the surface of the mercury. When this has been done, the instrument is rectified for the next day’s observation, without heating, cooling, separating, or at all disturbing the mercury, or moving the instrument. With a ther- mometer of this sort, Mr. Six observed the greatest degree of heat and cold that happened every day and night throughout the year 1781. In 1790 two thermometers were invented by Dr. John Ruth- erford; the one for registering the highest, and the other for re- gistering the lowest degree of heat to which the thermometer has risen or fallen during the absence of the observer. A new the spirit is condensed' self-registering thermometer has more recently been invented by Mr. Keith, of Ravelstone, which Dr. Gregory considers as the most ingenious, simple, and perfect, of any which has hitherto appeared. Its simplicity is so great, that it requires only a very short description to make it intelligible. It is constituted first of a thin glass tube about fourteen inches long, and 3–4ths of an inch caliber, close or hermetically sealed at top. To the lower end, which is open, there is joined a crooked glass tube seven inches long, and 4-10ths of an inch caliber, and open at its top, which, of course, is level with the middle of the first tube. The former tube is filled with the strongest spirit of wine, and the latter tube with mercury. This is properly a spirit-of-wine thermometer, and the mercury is used merely to support a piece of ivory or glass, for which is affixed a wire for raising one in- dex or depressing another, according as the mercury rises or falls. There is a small conical piece of ivory or glass, of such a weight as to float on the surface of the mercury. To the float is joined a wire called the float wire, which reaches upwards, where it terminates in a knee bent at right angles. The float- wire, by means of an eye fixed at its extremity, moves easily along a small vertical harpsichord wire. There are two indexes made of thin black oiled silk, which slide upwards or down- wards with a force not more than two grains. The one placed above the knee points out the greatest rise, and the one placed below it points out the greatest fall, of the thermometer. When the instrument is to be prepared for an observation, both indexes are to be brought close to the knee. . It is evident, that when the mercury rises, the float and float-wire, which can be moved with the smallest force, will be pushed upwards till the mercury becomes stationary. As the knee of the float-wire moves upwards, it will carry along with it the upper index. When the mercury again subsides, it leaves the index at the point to which it was raised, for it will not descend by its own weight; as the mercury falls, the float-wire does the same; it . therefore brings along with it the lower index, and continues to depress it till it again becomes stationary, or ascends in the tube, in which case it leaves the lower index behind it, as it had for- merly left the upper. The scale to which the indexes point is placed parallel to the slender harpsichord wire. That the scale and indexes may not be injured by the wind and rain, a cylin- drical glass cover, close at top, and made so as exactly to fit, is placed over it. The ingenious inventor has another improve- ment, which if upon trial it be found to answer, will make this thermometer as perfect as can be desired, provided there do not arise some errors from the variable pressure of the atmo- sphere. He proposes to adapt clock-work to this thermometer, in such a way as to register with the utmost precision the de- grees of heat and cold for every month, day, and minute, in the year. An account of this latter improvement may be seen in Nicholson's Journal, vol. iii. 4to. series, or Edin. Trans. vol. iv. ºpºpº 9p |&g 79/60 322 30|22; ſp; ſº /ø solspſ tº jº I [−I-T— #H+a JC-T-I-T-I-I-I-I-I-I-I-I-I----|--|-l º 20| AO || 0 *22222*2142 2222ſ22ſ22ſ22.É24;tºlo Tºlºl - Freezing. TITU) Złºczing. The common contrivance for a self-registering thermometer, now sold in most of the London shops, consists simply o two thermometers, one mercurial and the other of alcohol, hav- ing their stems horizontal, as in the annexed figure: the for- mer has for its index a small bit of magnetical steel wire, and the latter a minute thread of glass, having its two ends formed into small knobs by fusion in the flame of a candle. The magnetical bit of wire lies in the vacant space of the mercurial ºthermometer, and is pushed forward by the mer- cury whenever the temperature rises, and pushes that finid against it; but when the temperature falls and the fluid retires, this index is left behind, and consequently shews the maxi- mum. The other index, or bit of glass, lies in the tube of the spirit thermometer immersed in the alcohol, and when the spirit retires by depression of temperature, the index is carried along 1000 T H I. T H R DICTIONARY OF MECHANICAL SCIENCE. with it in apparent contact with its interior surface; but on in- crease of temperature the spirit goes forward, and leaves the index, which therefore shews the minimum of temperature since it "was set. As these indexes merely lie in the tubes, their resistance to motion is altogether inconsiderable. The steel index is brought to the mercury by applying a magnet on the outside of the tube, and the other is duly placed at the end of the column of alcohol by inclining the whole instrument. When the surface of the column of spirit is viewed by a magnifier, it is seen to have the form of a concave hemisphere, which shews that the liquid is attracted by the glass. The glass in that place is consequently attracted in the opposite direction by a force equal to that which is so employed in maintaining that con- cave figure; and if it were at liberty to move, it would be drawn back till the flat surface was restored. Let us suppose a small stick or piece of glass to be loose within the tube, and to pro- trude into the vacant space beyond the surface of the alcohol. The fluid will be attracted also by this glass, and form a concave between its surface and that of the bore of the tube. But the small interior piece being quite at liberty to move, will be drawn toward the spirit so long as the attractive force possesses any activity; that is, so long as any additional fluid hangs round the glass ; or, in other words, until the end of the stick of glass is even with the surface. Whence it is seen that the small piece of glass will be resisted, in any action that may tend to protrude it beyond the surface of the fluid; and if this resistance be greater than the force required to slide it along in the tube (as in fact it is,) the piece must be slided along as the alcohol contracts; so as always to keep the piece, within the fluid. And this fact is accordingly observed to take place. Professor Leslie, well known for his genius, has invented a differential thermometer, for the measurement of minute varia- | tions of temperature. It consists of two tubes, each terminat- ing in a small bulb of the same dimensions, joined by the blow- pipe, and bent in the form of a U, a small portion of dark co- loured liquor having previously been introduced into one of the balls. After many trials, the fluid best adapted to the purpose was found to be a solution of carmine in concentrated sulphu- ric acid. By managing the included air with the heat of the hand, this red liquor is made to stand at the required point of the opposite tube. tube, and divided into equal parts above and below that point. The instrument is then fixed on a stand. It is manifest, that when the liquor is at rest, or points at zero, the column is pressed in opposite directions by two portions of air equal in elasticity, and containing equal quantities of caloric. "Whatever heat, then, may be applied to the whole instrument, provided both bulbs receive it in the same degree, the liquor must remain at rest. But if the one ball receives the slightest excess of tem- perature, the air which it contains will be proportionally ex- panded, and will push the liquid against the air in the other bulb with a force varying as the difference between the temperatures of those two portions of air; thus the equilibrium will be de- stroyed, and the fluid will rise in the opposite tube. The de- grees of the scale through which it passes will mark the succes- sive augmentations in the temperature of the ball which is ex- posed to the greatest heat. So that this instrument is a balance of ſºme delicacy for comparing the temperature of its two SCa16S. It is a small variation from this thermometer that constitutes Mr. Leslie's Photometer. When thermometers are devised to measure very great degrees of heat, they are usually called by another name. See PyRoMETER. The thermometer and baro. meter together are very useful in determining the altitudes of mountains, &c. For this purpose they are fixed in such a frame as to be conveniently portable. See BARoMeter. THICK STUFF, planks thicker than those commonly used, which are placed opposite to the several scarfs or joinings in the frame of timbers. *, THIMBLE, a covering for the finger, made of any metal, to protect it from the needle, in use among tailors, milliners, and || all who are accustomed to sew. THIMBLE, in the language of ship-riggers, is a sort of iron | ring, whose Quter surface is hollowed throughout its whole cir- cumference, in order to contain in the channel or cavity a rope which is spliced about it, and by which it may be hung in any This is the zero of a scale fastened to that | particular situation. . Its use is to defend the eye of the rope which surrounds it, from being injured by another rope which passes through it, or by the hook of a tackle which is hung upon it. *NKING, in general, any act or operation of the mind, but its physical principles are concealed from the eye of human penetration. -- - THISTLE, Qrder of the, or of St. Andrew a military order of knighthood in Scotland. . THISTLE, in Agriculture, a well-known prickly weed, com- mon in cornfields. Of this troublesome plant there are various kinds. . They indicate strong land, but require the watchful care of the farmer. THOLES, i.e. bearers or fulcra, are small pins driven perpen- dicularly into the gunwale of a boat, and serving to retain the oars in that space which is called the row-lock; sometimes there is only one pin to each oar, as in the boats navigated in the Mediterranean sea. In that case, the oar is retained upon the pin by means of a strop, or of a cleat, with a hole through it, nailed on the side of the oar. THOR, in Mythology, an ancient deity, worshipped among the northern nations, from whom our Thursday derives its name. THORACIC, or THORACICI, a term applied to an order of fishes in the Linnaean system: the character of this order # that they have bony gills, and wentral fins directly under the thorax. - THORINA. An earth discovered in 1816 by M. Berzelius, in small quantities, in the gadolinite of Korarvet. It resembles Zllſ COInla. THORN, in Botany, a name given to all trees and shrubs of the larger kind, which are armed with spikes or prickles. - THOUGHT, a general name for all the ideas consequent on the operations of the mind, and even for the operations then- selves. • THRASHING, or THResh.ING, in Agriculture, the act of beating the corn out of the ears. There are several ways of se- parating corn from the ears; the first by beating it with a flail, which is properly what is called thrashing. The other method, still practised in several countries, is to make mules or horses trample on it backwards and forwards; this is properly what the ancients called tritura and trituratio. The Hebrews used oxen therein, and sometimes yoked four together for this purpose. Another way among the ancients was with a kind of sledge made of boards joined together and loaded with stone or iron, upon which a man was mounted, and the whole drawn over the corn by horses; this instrument was called traha or tribula. It is a rule among husbandmen, that the season for thrashing is as soon as the corn has sweated in the heap or mow. THRASHING MACHINES, were first constructed in Britain about the year 1732; and various improvements took place till the invention of Mr. Andrew Meikle in 1785, who obtained a patent which has since expired : fig. 1, represents the plan of elevation; fig. 2, the ground plan; and fig. 3, the essential parts of the machinery, so as to convey a tolerably accurate idea of his principle. A, fig. 1, and 2, is a large horizontal spur-wheel, which has 276 cogs, and moves the pinion B, having fourteen teeth. The latter imparts motion to a crown-wheel C, that is provided with eighty-four cogs, and moves a second pinion, D, which is furnished with sixteen teeth. This pinion D, turns the drum HIKL, fig. 1, 2, and 3, being a hollow cylinder, three feet Iſtay. . - 9. 22. É ğlg - # º （HH Tilliſ ||||||||||||||Iijīāīlīš ######### - - ſº-ºº: - T. |* sº. ' ** W. ſ | ſ º } : *mºmsº and a half in diameter, and placed horizontally : on its outside are fixed, by means of screw bolts, four scutchers, or pieces of T. H. R. T H U 1001 DICTIONARY OF MECHANICAL SCIENCE. wood, one side of which is faced with a thin iron plate: and which are disposed at an equal distance from each other, and at right angles to the axis of the drum. P, fig. 2, and 3, is an inclined board, on which the sheaves are spread, and whence they are introduced between two fluted cast-iron rollers, G, G, fig. 3, that are three and a half inches in diameter, and revolve about thirty-five times in one minute. These rollers being only three-fourths of an inch from the scutchers or leaves of the drum H I KL, fig. 1, and 2, serve to keep the sheaves steady while the scutchers a, b, c, d, fig. 2, and 3, move with considerable velocity, and thus separate the grain from the straw, while, both are thrown on the concave rack M, fig. 2, which lies horizontally F iga. F& 2 ja/2.5.45%/6.2/0 // 12 /3// with slender parallel ribs; so that the corn may pass through them into the subjacent hopper N, fig. 1, and 3. O, fig. 3, is a riddle or harp, through which the corn drops into a pair of fan- ners, P, ſig. 1 and 3, and from these it is generally obtained in a state fit for the market. Q R T S, is a rake consisting of four leaves, or thin pieces of wood; at the extremity of each is placed a row of teeth, e,f, g, h, that are five inches long. This rake moves in the concave rack M, fig. 2, in a circular direction ; while the teeth catch the straw that had been thrown by the scutchers a, b, c, d, into the rack, and remove it to the contiguous place W. W., fig. 1, represents the horse's course, which is 27 feet in diameter. X, ſig. 1 and 2, is the figure for supporting the beams on which the axle of the spur-wheel is fixed. Y, Y, Y, fig. 1, and Y, Y, fig. 2, shew the spindles, the design of which is to move the two fluted rollers, the rake, and the fanners. Hºnºuri; ºr ºr ºf §§ * _* #UN ~. 5%; ſº ºš Q R. * i s fift\}=><= **** lººp. Tº #irraº# º º & sº Sºº （ Nº. & N wr TI d A i Azºëſ, . vºte Wº: —º #||º i o i e 3 4 5 & 2 & 2 a j|| |$3. g | | º Biºl|| illſº trºº º t 3. º To the description now given we have only to add, that the drum has a covering of wood at a small distance above it, for the purpose of keeping the sheaves close to the scutchers. The number of persons requisite for attending the mill when working is six: one person drives the horses; a second hands the sheaves to a third, who unties them; while a fourth spreads them on the inclined boards, and presses them gently between the rollers; a fifth person is necessary to riddle the corn as it falls from the fanners, and a sixth to remove the straw. This machine can be moved equally well by water, wind, or horses. Mr. Meikle has made such improvements on the windmill as to render it’ much more manageable and convenient than formerly; and we are informed many such windmills are erected in different parts of the country. As to the comparative expense of these different machines, the erection of the horse-machine is least ; but then the expense of employing horses must be taken into consideration. One of this kind may be erected for 70l. A wa- ter-mill will cost 10l. more, on account of the expense of the water-wheel. A windmill will cost from 200l. to 300l. sterling. In thrashing machines, however, cheapness should not be the only ‘ºlderation. It often happens in machinery that things 106. apparently cheap are ultimately very dear. Thrashing of corn requires a strong power, to which neither weak men nor slight machines are competent. On this account strong and durable machines are to be recommended as cheapest in the end; per- forming more work, in a better manner, and not needing fre- quent repairs. Some other well-constructed thrashing-machines are described in Gray's Experienced Millwright, Bailey's De- Scriptions of Machines approved by the Society of Arts, in the Repertory of Arts and Manufactures, the 2d vol. of Dr. Brews- ter's Ferguson, and the 11th vol. of the Pantologia. With re- spect to the quantity of corn which a machine will thrash in a given time, it is not easy to give any precise information; the most important we have yet met with is given by Mr. Fenwick who found from numerous experiments that a power capable of raising a weight of 1000 pounds with a uniform velocity of fifteen feet per minute, will thrash two bolis (eight bushels) of wheat in an hour; and that a power sufficient to raise the same weight with a velocity of twenty-two feet per minute, will thrash three bolls of the same grain in an hour. From these facts, this gentleman has computed the following table, which is applicable to machines that are driven either by water or horses. Gallons of Gallons of Gallons of Water per mi- water per mi- Water per mi- Bolls thrash- nute, ale mea-|nute, ale mea-|nute, ale mea-|, Number of Bolls ed in 9 hours Sure,discharg- |sure,discharg-|Sure,discharg- |horses work- of wheat and a half ac. ed on an over-led on an over-led on an over-ling 9 hours; thrashed in tual working shot wheel 10|shot, wheel 15|shot wheel 20 and a half. an hour. or in a day.” feet in diame-I feet in diame-l feet in diame- ter. ter. ter. - 230 160 130 I 2 19 390 296 205 2 3 28% 528 380 272 3 5 47% 660 470 340 4 7 66% 790 565 400 5 9 85% 970 680 500 6 10 95 { 2 3 4 5 6 The first four columns of the preceding table contain dif- ferent quantities of impelling power, and the last two exhibit the number of bolls of wheat in Winchester measure, which such powers are capable of thrashing in an hour, or in a day. Six horses, for example, are capable of thrashing ten bolls of wheat in an hour, or ninety-five in the space of nine hours and a half, or a working day; and 680 gallons of water discharged into the buckets of an overshot water-wheel of 15 feet diameter during a minute, will thrash the same quantity of grain. THRAVE, or THREAve of CoRN, twenty-four sheaves, or four shocks of six sheaves to the shock, though in some countiès they only reckon twelve shocks to the thrave. THREAD, a small line made up of a number of fine fibres of any vegetable or animal substance, such as flax, cotton, or silk ; from which it takes its name of linen, cotton, or silk thread. THREATENING LETTER. If any person shall send any let- ter threatening to accuse any person of a crime punishable with death, transportation, pillory, or other infamous punishment, with a view to extort money from him, he shall be punished at the discretion of the court with fine, imprisonment, pillory, whipping, or transportation. THROAT, among Seamen, is a name given to that end of a gaff which is next the mast, and is opposed to peek, which implies the outer end; hence, Throat Brails, are those which are attached to the gaff close to the mast. Throat Halliards, ropes or tackles applied to hoist the inner part of the gaſt, and its appendent portion of the sail. THRUM, (To,) a phrase at sea, which signifies to insert in a sail or mat, &c. through small holes made by a bolt-rope needle, or a marline spike, a number of short pieces of rope yarn, or spun yarn. s - THUMMERSTONE. This stone was first described by Mr. Schreber, who found it near Balme D'auris in Dauphine, and, gave it the name of shorl viole. It was afterwards found near Thum in Saxony, in consequence of which Werner called it Thummerstone. It is sometimes amorphous, but more com- monly crystallized. . 11 Y 1002 T I D T I I, DICTIONARY OF MECHANICAL SCIENCE. * THUNDER, the noise occasioned by the explosion Of a flash of lightning passing through the air; or, it is that moise which is excited by a sudden explosion of electrical clouds, which are therefore called thunder-clouds. The rattling in the noise of thunder, which makes it seem as if it passed through arches, is probably owing to the sound being excited among clouds hanging over one another, and the agitated air passing irregularly between them. The explosion, if high in the air, and remote from us, will do no mischief; but when near, it may and has, in a thousand instances, destroyed trees, animals, &c. This proximity, or smail distance, may be estimated nearly by the interval of time between seeing the flash of lightning, and hearing the report of the thunder, estimating the distance after the rate of 1:142 feet per second of time, or 33 seconds to the mile. THWARTS, the seats or benches of a boat whereon the rowers sit to manage the oars. THYMUS, THYMe, a well-known aromatic garden plant, highly useful for domestic and medicinal purposes. TIARA, an ornament with which the ancient Persians covered their heads. - TICK, a troublesome insect which infests cows, goats, sheep, dogs, horses, and occasionally man. . TIDE, a regular periodical current of the water, setting alternately in a flux and reflux, and is produced by the influence of the moon. Locke, in describing the theory of the tides, observes, “That motion of the water, called tides, is a rising and falling of the sea; the cause of this is the attraction of the moon, whereby the part of the water in the great ocean which is nearest the moon, being most strongly attracted, is raised higher than the rest; and these two opposite elevations of the surface of the water in the great ocean following the motion of the moon from east to west, and striking against the large coasts of the continents; from thence rebound back again, and so make floods and ebbs in narrows, seas, and rivers.” & The great Sir Isaac Newton undertook to explain the doc- trine of the tides upon the two great principles of gravity and attraction. However irregular they might be in certain in- stances, and with a view to certain objects, it was evident, that from the stated intervals of the time which they preserved, some common and general cause must exist to produce such a regu- lar effect. Continuéd observation had ascertained one striking and remarkable fact on all the coasts of the British dominions in Europe, and along the coasts of Holland, France, Spain, and Portugal, that the hour of high water, considered generally, was regularly and uniformly at a certain interval or portion of time after the moon had passed the meridian of such place. The acute and sagacious mind of this philosopher was, from mature deliberation, and attention to this fact, soon convinced that the moon had an influence upon the great body of the waters of the ocean, and that the only remaining subject of consideration was, to discover how far this principle would agree with the different quantity of waters which were accumulated at those intervals on different days. On this subject he might thus judi- ciously argue with himself: If it be true that the moon has an influence on the waters of the occan, so as to occasion their accumulation in a regular and periodical way, which cannot be done by any thing but the force of attraction, it is equally probable, that the other heavenly bodies should have some influence to the same purpose. But the sun alone, from his magnitude, is capable of doing this in any considerable or sen- sible degree, and though from his distance that effect and influence be very much lessened, yet, upon calculation, it would be found to bear a proportion extremely well suited to obviate the remaining difficulty. First, it should be observed, that the earth has a daily revolution on its axis every twenty-four hours from west to east, which occasions the sun and other heavenly bodies apparently to move from east to west. But the moon, from her actual motion in the heavens towards the east, of a little more than twelve degrees daily, or near forty-nine minutes of time at a medium, occasions her coming upon the meridian of any place later by forty minutes daily than on each next preceding day, so as to take up about twenty-nine days and a half on an average from one new moon to another. Now, if both the sun and moon are supposed to have an attractive power and influence on the waters in the ocean, it must follow, that when they happen to be on the meridian at the same time, or nearly so, this attraction of each, whatever may be the pro- portion between them, must be the same way. It will from hence follow, that the effect of the sun’s influence must in this case be added to that of the moon, and consequently an in- creased accumulation of waters must be produced. This is in reality the case at every new moon, when these two attractive bodies affect the waters of the ocean the same way, and cause higher tides, which are usually known by the name of spring tides. This will also account for the same sort of tides at the full moon, when the moon is at the greatest distance from the sun, or due north when the other is south. For we shall pre- sently see, that the accumulated tides will always take place on the opposite parts of the world, to preserve a proper equili- brium, unless where other causes operate to the contrary; and therefore, though the two attracting bodies be in opposite parts of the heavens, they will operate jointly, as at the new moon, to produce high tides. On the contrary, when they are at the distance of a quarter of the heavens from each other, or ninety degrees, their influence will be manifestly different from each other, and the attraction will operate on different parts of the ocean, so as to counteract one another. Hence it would follow, that if the attractive power of these two bodies were equal, they would then destroy each other, as their united power at the full and new moons would be double to either of them singly. This, however, is not the case, though it is cer- tain that at the time of the quarters of the moon, when the moon still evidently retains a prevailing influence, it is much counteracted by the attractive power of the sun, so that the tides are comparatively much less, and are known by the name of neap tides. It is likewise to be observed, that the tides, from the prevailing influence of the moon, would always naturally follow her from east to west, if the obstructions of land lying in the way did not prevent it. But water, as a ponderous body, though fluid, will more speedily seek to preserve its own level, and is less liable to interruption from slight causes, than the air or atmosphere, so that whatever impediments it meets with, it turns round the shortest points of land for this purpose, and seeks every creek and river in its course, that no part of the sea or ocean may be deprived of its share of the tides, and to recover its level. It will be evident on the principles of attraction and gravita- tion, that as the hemisphere nearest to the moon will be imme- diately under the effect of her attraction, and consequently, the waters of that half be prevented from gravitating towards the other, the opposite hemisphere will have less than its share of attraction, and consequently the gravitation will be diminished, from whence the waters of the extreme part will be higher than in any other part of the hemisphere, so that the tides will then be highest at the same time. Hence, at the distance of ninety degrees, where this influence can be little if at all perceived, the waters will be at liberty to descend towards the centre by the natural power of gravitation, and will therefore in those places be lowest. It has also been concluded, that where the moon’s meridian altitude is great, the tides will be increased when she is above the horizon ; and, on the contrary, that when her meridian depression is great, the night tides will be most considerable. This holds true in a less degree of the sun, and especially at the new moon, if she has north declination in summer, and south declination in winter. Also, if the moon is in such a part of her orbit as to be at the nearest distance from the earth, it will considerably add to the influence of her attrac- tion; and it has been known to cause uncommonly high tides when this happens at the time of new or full moon. Generally understood, it has been noted, that the morning tides are the highest in winter, and the evening tides in summer. It has been observed, that the intervention of land causes a great alteration in the tides. This will shew why there are little or no tides in small inland seas, such as the Baltic and Mediter- ranean, where the attractive influence of the sun and moon must be nearly equal at both the extremities, and cannot there- fore sensibly affect the waters. It is also certain, that the tides are very inconsiderable in high latitudes, because the sun and moon more immediately act towards the equator, and raise the water towards the middle of the torrid zone, which must consequently render the waters of the frigid zone compara- T I D º T I D DICTION ARY OF MEO, HANICAL SCIENCE, 1003 tively low, by depriving the neighbourhood of the poles, of those waters that are thus attracted towards the middle of the globe. We shall now notice the proportion of the attractive influence of the sun and moon, as to their effect on the waters, and then point out the progress of the tides along the coasts of Europe. It has been observed, that on a supposition that the joint force being ascertained in any particular port at twelve feet, at a medium height of spring tides, without any extraordinary addi- tion or diminution of the attracted power, that of neap tides has been found to be somewhat less than eight feet. Hence, as the united force of the attraction of the sun and moon is twelve, and by a contrary effect is reduced to eight, that of the moon singly must be equal to ten, and that of the sun to nearly two, and this proportion, generally considered, will almost con- stantly hold good, on all the coasts of the united kingdom. There is another principle of the solar system, on which also this matter may be demonstrated. For as all the bodies attract each other mutually, but in an inverse ratio, in proportion to the squares of their distances, conjointly with their magnitude, this influence of the sun will also be found nearly to coincide with this general and fundamental law of the universe. It has been seen that the natural course of the tides and cur- rents of the ocean must be from east to west. This would be the case nearly, and almost uniformly, if the interposition of extensive continents did not prevent it. From the northern ex- tremity of Europe, at the north end of Wiegat's Straits, in lat. 78 degrees N. to the Cape of Good Hope, in lat. 34 deg. S. there is no known passage for the waters of the ocean, in that or any other direction, but along the coasts. The medium situation between these two extremes, is about 22 deg. N. which, is near Cape Blanco on the west coast of Africa. But the least shadow of a chart or map must be sufficient to satisfy any per- son of the impossibility of the flood tides setting there to the westward, because the continent for 56 deg. to the N. and S. entirely bounds that sea on the east. If therefore the tides are not totally interrupted by this vast extent of continent, they must come in either from the north or along the coast of Europe in a direction southward, or from the south in a direction north- ward along the west coast of Africa from the Cape of Good Hope. Such being the state of the case from argument, so it is in fact, as proved by common observation and experience ; for it is well known that the flood tide sets to the southward along the west coast of Norway, from the North Cape to the Naze, for an extent of 13 deg. to the entrance of the Baltic Sea, and that from thence it proceeds southward to the coast of Great Britain, supplying every port successively in its passage. The largetisland of Great Britain breaks the regular course of the waters, and causes a division on their approaching that coast; and as the current comes from the northward, the coast of Scotland, as must naturally be expected, will first have the tide of flood, before the parts which are farther situate to the south. As the island of Great Britain divides this current into two channels, its operation on the eastern coast may first be re- garded. The natural tendency to the west is here interrupted by the land, so that it must run to the southward as the only possi- ble direction it can take. Hence it is found that at Aberdeen, on the coast of Scotland, the tide will be at its height on full and change days at a quarter before one o'clock, but that it will not be high water at Tinmouth Bar, on the coast of North- umberland, till three o’clock on the same days. All the inter- mediate ports, from thence to the Spurn, will have it progres- sively latter, where it does not reach till about five o’clock; and before it gets as far as Yarmouth Road, it will be at least eight o'clock. From thence it runs on still to the southward to Harwich, which it reaches at half past ten, and to the Nore, to which it does not come till twelve. The other channel, which passes the north point of Scotland, and runs along the west coast of Great Britain at the same time, is subdivided into two channels by the interposition of Ireland. But the tide of flood between the south-west of Scotland, and the north-east point of Ireland, from the narrowness of the sea, is much the least in quantity, and therefore makes a much slower progress after its access to St. George's Channel, so as not to get farther than about the parallel of latitude of the Isle of Man. It would, nevertheless, advance forward to the south, if, as it will appear, a superior and controlling tide did not here put a ter- nutes later than on each preceding day respectively. the next preceding tide, and so on progressively. times happen that in mentioning the time of high water at any mination to it. During this time, the main part of the western branch of the tide has been rapidly hurrying along the west coast of Ireland, in an open sea, where it has nothing to inter- rupt it till it arrives at the south-west part of that kingdom, so as to be at Cape Clear soon after four o'clock, which is an hour before it could reach the Spurn by the east channel. Hence, therefore, it must naturally turn round the south coast of Ire- land, and it will have reached Waterford by five o’clock, near the south-east extremity of Ireland. Here, then, the tide will not only push on to the eastward for the English channel, but as the tide from the southward has been quickly setting to the north-east across the bay of Biscay, it will unite with this cur- rent to supply the deficiency of water in the English channel and the Irish Sea, or St. George's channel, and consequently proceed along the south of England and the north coast of France. For these two tides, by their joint influence, cause the tides along the south coast of Cornwall to be at the highest at new and full moon, some time in the interval from five to six o'clock, and along the east coast of Ireland a branch of them will slowly pass along to fill up the bays and channels there and on the coast of Wales, till it meets the branch which came in from the north through the narrow sea between Ireland and Scot- land. At the time of this meeting it will be high water in the sea, which is between ten and eleven o’clock. At the same time, the main branch of these united tides is pressing along up the English channel till it meets the tide, or first principal branch of the current, which had washed the north. east and east coasts of Scotland and England, somewhere between Beachy Head and Dungeness; or, as some persons rather conclude, not far from the Godwin. If we take farther notice of the effects of these several tides on large rivers and bays, it will be farther evident that they will occupy some time, while the main body of those tides is pursuing its general progress along the adjacent coasts of the seas it passes through. Thus it is found that the tide will be an hour in passing up from the point of the Spurn to the town of Hull, or Kingston upon Hull, where it is not high water on full and change days till six o'clock. And the union of the two tides in the neighbourhood of the Godwin sands oc- casions a vast influx of water into the river Thames, and contri- butes to produce the powerful tides which run up that river to London. The same reason will also afford a solution to the difficulty of the slow advance of the tides in St. George’s or the Irish sea; for if the narrowness of the strait between Scotland and Ireland on the north be attended to, and the bending of the coast round the Mull of Galloway to the eastward as far as Solway Frith, that small influx of water must be a long time in filling the several bays and inlets of that coast; so that, although the tides do not enter the southern part of this sea till some hours after, the more spacious inlet of that extremity will admit a propor- tionably greater quantity of water. Hence, after this branch of the tide has filled up the Bristol channel or Severn sea on the east, and Cardigan Bay to the north-east, which must em- ploy a space or interval of some hours, it passes up to the north of Dublin, and meets the former tide in the parallel of the Isle of Man; from whence, as soon as it is high water, the ebb tides re- turn back again by their respective channels, till they are lost in the main ocean of the Atlantic. The time of high water at any particular port must therefore be determined from observation and experience, as, from these interruptions, it is clear that no general principles can be laid down, on which it can be resolved from the longitude or compa- rative situation of any place on the face of the globe. general rule already laid down for the intervals of high water will always prevail; and when once the time of high water has been ascertained on the days of new and full moon at any port, the successibn of those tides will be daily about 49 mi- It must always however be remembered, that there is another tide in the intermediate time, or about 12 hours and 24 minutes after It may some- particular port, cape, headland, or any other remarkable place of the sea or ocean, it may be expressed generally, or without any reference to its being understood of the time on the very days of new or full moon; which perhaps, to seamen, could But the 1004 T I D T I IL DICTIONARY OF MECHANICAL SCIENCE. scarcely admit of any doubt, but to others, less conversant with their general language and modes of speech, may be less intel- ligible. We have sometimes also expressed ourselves generally of the time of spring tides; by which, likewise, is constantly meant the precise day of new or full moon, though the tides for two or three days are frequently represented by that term ; and indeed, it has been observed from experience, that the highest tides are not usually till the third or fourth tide, according as the day or night tides are highest from other causes, after the actual new or full moon, whereas, in, speaking of the time of spring tides generally, it is always to be understood of the very day. The time of high water being accordingly ascertained by observation at each particular port, the next conclusion result- ing from thence has been to represent the point of the compass, being first corrected for variation on the day on which the moon is at that time. Having, therefore, determined this, according to the proportion of 11 degrees and a quarter for each point of the compass, pilots and seamen in general have attended to the rule in laying down the time of high water on the intermediate days. between the spring-tides. This is, in other words, to allow three quarters of an hour for each point of the compass; and on this foundation it is that in places where it is high water at noon on | full and change days, as at Southampton or Ostend, the tide is said to flow north and south at 12 o'clock. Thus also if the moon on those days bears 1, 2, 3, or more points to the east- ward or westward of the meridian of any place at the time of high water, the tide is said to ſlow on such a point. For exam- ple, if the moon bears S.E. at the time of high water at Poole in Dorsetshire, the tide will here be said to flow at S. E. and N. W. and if E. or W. at Plymouth in Devonshire, it will be said to flow east and west. But it is a very improper way to depend on the point of the compass alone for the time when the moon is to be at high water, unless it has been converted into time, and ascertained by the interval after passing the meridian. Thus, for instance, if it were understood that the moon is always to be east or west at the precise time of high water at Plymouth, conclusions the most gross, erroneous, and dangerous, would be the result ; because when the moon has a high north declination, it may happen that she may not be due east till near eight o'clock in the morning at Plymouth, which will almost be two hours after high water, and it would on the same day be due west soon after four o’clock in the afternoon, which will be nearly two hours before high water. It is needless to enlarge on the danger of abiding by this mode of calculation, without converting it into time at the rate of three-quarters of an hour for every point of the compass. But the general and only safe rule is, to say, that it will be high water at six hours after the moon has passed the meridian. It is high water in some places on the shore, or by the ground, while the tide continues to ſlow in the fair way or offing, as it is called, by which term is understood, that part of the sea in the neighbourhood, or at no great distance from any coast, where the tide-way is not particularly interrupted by the ad- jacent shore or high land. For this state of the tides it is cus- tomary to say, that the water flows tide and half tide, or tide and quarter tide, and the like, thereby considering the usual run of the tide at six hours, and the half tide at three hours, &c. When, therefore, the current or stream of the fair way in the offing of any coast is said to run tide and quarter tide, for in- stance, it means that the stream runs an hour and a half longer in the offing than it does by the shore, and consequently that it does not begin to run so soon any particular way at a distance from the coast as it does close by the land, by that interval of time. There is yet one circumstance more to be noted respecting the mode of calculating the time of high water on the interme- diate days between the spring-tide days. We have already pointed out the extremely dangerous notion of reckoning the tides by the points of the compass for any particular ports, and especially those which are nearest to the east and west. There is likewise another irregularity of considerable import- snce, which is, applying too generally and successively the rule of adding 49 minutes daily to the time of high water on each pre- ceding day. Experience has proved this common method of calculation to be frequently erroneous. With regard to the relative force of the tide on a ship floating *herein, see the article CURReNT. TIDE-GATE, a place in which a tide runs with great velocity. To TIDE, to work in or out of a river or harbour, or channeſſ, by favour of the tide, and anchoring whenever it becomes ad- We rSe. - - TIDEs Man, an officer appointed by the custom-house to re- side on board of merchant ships while they have any custom- able goods on board. - TIDE Mills, as their name imports, are such as employ for their first mover the flowing and ebbing tide, either in the sea or a river, and particularly the Thames, the Humber, and the Severn, in which the tide rises to a great height, furnishing a very pow- erful mover to drive any kind of machinery, and would allow of tide mills being very advantageously constructed upon their banks. The erection of such mills is not to be recommended universally, as they are attended with a considerable original expense, besides that some of their parts will require frequent repairs; but in some places where coals are very dear they may, on the whole, be found less expensive than steam engines to perform the same work, and may on that account be preferred even to them. T1De Way, the channel in which the tide sets. Tide. Waiters, or TIDESMEN, are inferior officers belong- ing to the custom-house, whose employment it is to watch or attend upon ships until the customs are paid. TIER, a name given to the range of cannon mounted on one side of a ship's deck. TIER of the Cable, is a range of the fakes or windings of the cable, which are made within one another in a horizontal po- , Sition. Cable TIER, the space in the midst of a cable when it is coiled, also the place in which it is coiled. TIER, also implies a range of casks in the hold ; hence we say, the Ground TIER, or that which is next above the keel- son, the second tier and upper tier. TIERCE, or TERCE, a measure of liquid things, as wine, oil, &c, containing the third part of a pipe, or forty-two gallons. TIGER. See FELIS. TIGER Shell, a beautiful species of voluta, of a dusky red colour, spotted all over with large irregular blotches of white. TIGHT, the quality whereby a vessel resists the penetration of any fluid, whether compressing its surface, or contained within it. Hence a ship is said to be tight when the planks are so solid as to prevent the entrance of the water, and a cask is called tight when none of the liquid contained therein can issue through or between the staves; in both senses it is opposed to leaky, which article see. TIGILLUM, a word used by chemists to express the tile with which they cover the mouth of their crucibles; and, by others, for the crucible itself. TILE, in building, a sort of thin brick, used on the roofs of houses; or more properly a kind of clayey earth, kneaded and moulded of a just thickness, dried, and burnt in a kiln like a brick, and used in the covering and paving of different kind of military and other buildings. - TILIA, in Botany, the Lime Tree, of which there are a great variety of species. - TILLAGE, the cultivating of land, or the means of bringing it into a state of preparation for depositing the seeds, and the growth of different crops. TILLER, the bar or lever employed to turn the rudder in steering. See the article HELM. - TILLER Rope, the rope which forms a communication between the fore end of the tiller and the wheel, and is usually made of untarred rope. TILT, a small canopy or awning of canvass or other cloth, extended over the stern sheets of a boat, and supported by iron work, or broad laths of flexible wood, incurvated. The tilt is principally used to keep off rain, as an awning is intended to defend from the sun's heat. TILT, the covering of a cart, waggon, or other carriage, sup- ported by hoops, and easily removeable when occasions require. TILT Boat, is a boat covered with tarpawling or sail-cloth, to shelter the passengers, and such goods as might otherwise be exposed to the action of sun or rain. TILT Hammer, a large and heavy hammer, put in motion by a water wheel or steam-engine. Cogs being brought to bear on * T I M T J M 1005 DiCTIONARY OF MECHANICAL SCIENCE. the tail of the hammer, its depression causes the head to be elevated, which, when liberated, falls with considerable force by its own specific gravity. Tilt mills work on the same principle. Tilting of Steel, is the process by which blistered steel is rendered ductile. This is done by placing it under the tilt hammer. TIMBER, includes all kinds of felled and seasoned woods. Of all the different kinds known in Europe, oak is the best for building, and even when it lies exposed to air and water there is none equal to it. Fir timber is the next in degree of good- ness for building, especially in this country, where they build upon leases. It differs from oak in this, that it requires not much seasoning, and therefore no great stock is required before- hand. Fir is used for flooring, wainscoting, and the ornamental parts of building within doors. Elm is the next in use, espe- cially in England and France; it is very tough and pliable, and therefore easily worked ; it does not readily split, and it bears driving of bolts and nails better than any other wood; for , which reason it is chiefly used by wheel-wrights and coach- makers, for shafts, naves, &c. Beech is also used for many purposes; it is very tough and white when young, and of great strength, but liable to warp very much when exposed to the weather; and to be worm-eaten when used within doors; its greatest use is for planks, bedsteads, chairs, and other house- hold goods. Ash is likewise a very useful wood, but very scarce in most parts of Europe; it serves in buildings, or for any other use, when screened from the weather; handspikes and oars are chiefly made of it. Wild chesnut timber is by some esteemed as good as oak, and seems to have been much used in old buildings; but whether these trees are more scarce at present than formerly, or have been found not to answer so well as was imagined, it is certain this timber is now but little used. Walnut-tree is excellent for the joiner’s use, it being of a more curious brown colour than beech, and not so subject to the worms. The poplar, abel, and aspen trees, which are very little different from each other, are much used instead of fir, and look well.—The goodness of timber not only depends upon the soil and situation in which it stands, but likewise on the season wherein it is felled. In this, people disagree very much ; some are for having it felled as soon as the fruit is ripe, others in the spring, and many in the autumn. But as the sap and mois- ture of timber is certainly the cause that it perishes much sooner than it otherwise would do, it seems evident that tim- ber should be felled when there is the least sap in it, viz. from the time that the leaves begin to fall till the trees begin to bud. This work usually commences about the end of April in Eng- land, because the bark then rises most freely ; for where a quan- tity of timber is to be felled, the statute requires it to be done then for the advantage of tanning. After timber has been felled and sawed, it must be seasoned ; for which purpose some ad- vise it to be laid up in a very dry airy place, yet out of the wind and sun, or at least free from the extremities of either: and that it may not decay, but dry evenly, they recommend it to be daubed over with cow-dung. It must not stand upright, but lie all along; one piece over another, only kept apart by short blocks interposed to prevent a certain mouldiness, which they are otherwise apt to contract in sweating on one another; from which arises frequently a kind of fungus, especially if there be any sappy parts remaining. Others advise the planks of timber to be laid for a few days in some pool or running stream, in order to extract the sap, and afterwards to dry them in the sun or air. By this means, it is said, they will be prevented from either chopping, casting, or cleaving, but against skrinking there is no remedy. Some again are for burying them in the earth, others in a heat, and some for scorching and seasoning them in fire, especially piles, posts, &c. which are to stand in water or earth. The Venetians first found out the method of seasoning or charring by fire; which is done after this manner; they put the piece to be seasoned into a strong and violent flame, in this they continually turn it round by means of an engine, and take it out when it is every where covered with a black coaly crust; the internal part of the wood is thereby so hardened, that º: earth nor water can damage it for a long time after- WarC, S. º Timber Trees, in Law, are properly oak, ash, and elm. In •omºticular countries, by local custom, other trees being 06. - commonly there made use of for building, are considered as timber. Of these, being part of the freehold, larceny cannot be committed ; but if they be severed at one time, and carried. away at another, then the stealing of them is larceny. And by several late statutes, the stealing of them in the first instance is made felony, or incurs a pecuniary forfeiture. For the bet- ter preservation of roots, shrubs, and plants, it is enacted by 6 George III. c. 48, that every person convicted of damaging, destroying, or carrying away any timber tree or trees, or trees. likely to become timber, without consent of the owner, &c. shall. forfeit for the first offence not exceeding 201, with the charges attending ; and on non-payment shall be committed for not more than twelve, nor less than six months ; for the second offence a sum not exceeding 30l. and on non-payment shall be committed for not more than eighteen, and not less than twelve months; and for the third offence, is to be transported for seven years. All oak, beech, chesnut, walnut, ash, elm, cedar, fir, asp, lime, sycamore, and birch trees, shall be deemed and taken to be timber trees, within the true meaning and provision of this act. Persons convicted of plucking up, spoiling, or taking away any root, shrub, or plant, out of private cultivated ground, shall forfeit, for the ſirst offence, any sum not exceeding 40s. with the charges; for the second offence, a sum not exceeding 51, with the charges; and for the third offence are to be trans- ported for seven years. A power is given to justices of the eace to put this act in execution. TIMBERS, the ribs of a ship, or the incurvated pieces of wood branching outward from the keel in a vertical direction, so as to give strength, figure, and solidity to the whole fabric. One timber is composed of several pieces united into one frame, which is accordingly called a frame of timbers, by the artificers. Square TIMBERs, are those whose planes are perpendicular to the keel. Cant TIMBERs, are those which are placed obliquely on the keel, as at the extremities of a ship. - Knuckle TIMBeRs, are the foremost cant timbers on a ship's bow; the hind most on the quarter are termed fashion pieces. TIM BER and Room, or Room and Space, is the distance between the moulding edges of two adjoining timbers, which always contain the breadth of two timbers, and sometimes two or three inches between them. Filling TIMBERs, are those which are put up between the frames. It must be observed, that one mould serves for two timbers, the fore side of the one being supposed to unite with the after side of the other, and so make only one line, which is actually the case in all the frames, which in some ships are every third, and in others every fourth timber. The frames are first put up and fastened to the ribands, and afterwards the filling timbers are put up. TIMBER Heads. See the article KBVEL HEADs. ' . TIME, a measure or portion of infinite duration. It is gene- rally ascertained by the motions of the heavenly bodies. - TIME, in Music, is an affection of sound, by which we de- nominate it long or short with regard to its continuance. . . TIME Keepers, in a general sense, denotes instruments adapt- ed for measuring time. See CHRONoMeter. TIMEKEEPER, or TIM epiece, an instrument adapted for measuring time. See the article LoNG it Ude. & The following remarks on time-keepers were communicated by Joseph Whidbey Esq. master attendant at Sheerness yard, master of the Discovery sloop, and afterwards of the Sanspareil, and who surveyed 3000 leagues of the N. W. shore of America.--"When a time-keeper is received on board a ship, the greatest care should be taken to have it immediately secur- ed in some convenient place in the cabin, where it may be the least liable to be moved during the voyage: it should never be touched but at the time of winding up, which ought to be at noon, and then with the greatest care, particularly avoiding circular motion. The makers of these instruments will aſſirm, that it is unnecessary to be thus particular in the care of them, and will tell you they may be carried about in the pocket, and moved from place to place, without being the least affected by it. I can only say, that I have been in the habit of using time-keep- ers for some years, and, notwithstanding the sanguine expecta- tions of the makers as to their perfection, in my experience I have *} the above precautions necessary. I have frequently 11 i 1006 T I M. T I M. DICTIONARY OF MECHANICAL SCIENCE, known time-keepers alter their rates, in carrying them from the ship to the observatory, and again from the observatory to the ship, when I have every reason to suppose that, had they re- mained quiet on board, there would have been no alteration in their rates. I do not mean to say this will universally be the ease, I have had many instances to the contrary; I should hope that as so many skilful men are at this time employed to bring this piece of mechanism to perfection, they will ultimately suc. ceed in obviating every objection that possibly can be started against them. Not that I allow the above to be an objec- tion against time-keepers, because a rate may be given them without moving them from the place where they were first fixed, as I shall explain hereafter. I would only express, that too much care cannot be taken of an instrument which will answer so grand a purpose as that of ascertaining a ship's exact position, almost at any time, in any part of the ocean. When a time-keeper is received on board, its rate, or the num- ber of seconds it gains or loses in twenty-four hours, with the time which it was fast or slow of mean time at Greenwich, on some certain day, is given from the observatory with it. It will not be amiss to note this rate carefully every day at noon, in a book kept for that purpose, so that it may be known at any time, without any farther calculation, what the time-keeper is fast or slow of mean time at Greenwich. If the time-piece is slow of mean time at Greenwich, and losing, add its daily rate to its error every day. What is here meant by error is the quantity the time-piece is fast or slow of the meridian reckon- ed from, and not the error that is occasioned by any irregula- rity in the going of the machine, and which, to the extent of it, would occasion a wrong deterinimation of the longitude. This sum must be added to the time it shews, to give Greenwich mean time; if it is slow, and gaining, subtract its daily rate and add the remainder to the time shewn by it for the Greenwich mean time. . If the time-keeper is fast, and gaining, add the daily rate, and subtract the sum ; or if it is fast, and losing, subtract the daily rate, and subtract the remainder from the time shewn by the time-keeper, to obtain the Greenwich mean time. It is evident that when the time-piece is fast, and losing, its error will decrease till it becomes slow ; and then the error will in- crease; also, if it is slow, and gaining, its error will decrease till it becomes fast, and then will increase. When by this cor- rection of the time-piece the mean time at Greenwich is known, all that is wanted is the mean time at the ship. The difference between them is the longitude of time, which is west, when the Greenwich mean time is the greater of the two, and east when it is the less. To prevent the moving of a time-piece, the ob- server should be provided with a pocket watch, having a se- conds hand. This should be compared with the time-piece, noting the difference both immediately before and after taking altitudes. If the diſference be not the same before and after, correct it in the proportion of the elapsed times, before you apply it to the time shewn by the pocket watch, to give the time shewn by the time-piece. The rate of a time-piece should often be tried, and if it is found to have altered, a new rate should be given. The alteration may be discovered, and a new rate given as follows: In any harbour, which has been regu- larly surveyed, and the latitudes and longitudes well ascertain- ed, the bearing of any two points will determine the ship’s po- sition on the chart: thus the ship's latitude is known. Let alti- tudes be taken, and from them find the longitude by the time- piece: if this differs materially from the ship's longitude, it is fair to conclude that the time-keeper has altered its rate.—If the ship stays a week or ten days in the same place, a new rate may be given it, by taking altitudes as often as is convenient until the ship sails; noting the difference of the longitudes given by the time-piece the first and last day; then turning this dif- ference into time, and dividing that time by the number of days from the time of taking the first altitudes, to the time of taking the last ; the quotient will be an increase, or decrease, to be applied to the old rate. If the place be to the westward of Greenwich, the Greenwich time is greater than the time at the place; consequently, if the time-piece gives a greater longitude on the last day than it did at the first, it is gaining; if a less, it is losing ; if the place is to the eastward of Greenwich, the con- trary is true. By this mode, the rate of a time-piece may be found on board; and, indeed, I would always recommend this | method, particularly to those who have the charge of navigating a ship. Undoubtedly the best and surest mode of finding the rate of time-keepers, is by a well-regulated clock on shore, or by equal altitudes taken by an astronomical quadrant. As nei- ther of these can be used on board a ship, a substitute is re- quired. I know of none better than a quicksilver horizon ; which with care can never lead to any error: it is therefore far preferable to the sea horizon, which is liable to a considerable error. When I have been in an observatory, finding the rate of time-pieces by a well-adjusted astronomical quadrant, I have frequently, for experiment sake, tried the quicksilver horizon, and brought out the rate the same as by equal altitude. I have found the quicksilver horizon capable of fixing the latitude of a place nearly as accurately as an astronomical quadrant. It is made small enough to be carried in the pocket. With a sextant it may be called a portable observatory; and a person may with these two instruments regulate his time-pieces, wherever he may chance to stop. The quicksilver horizon shews twice the true altitudes, i.e. Suppose the sun's altitude is taken by a quicksilver horizon, and measures on the sextant 90°, half that sum, or 45°, will be the altitude of the sun’s lower limb ; which is to be treated as a common altitude, except that there is no correction for the dip of the horizon. “Let us mow suppose a time-piece to be fixed in a ship ; the observer to be provided with a quicksilver horizon, a sextant, and a pocket watch with a seconds hand, which goes tolerably well, and that he wishes to find the rate of his time-piece : let him set his pocket watch to the same second with the time-piece, if it is a stop watch; otherwise let him compare it, noting the difference ; then let him go on shore with his quicksilver hori- zon, and take altitudes; let him immediately return on board, and compare again, and if the pocket watch has altered its dif- ference from the time-piece, let him make the proper proportion for the error, according to the elapsed times, as above directed, to find the time which the time-piece shewed when the altitudes were taken ; with this, the altitudes may be used as if the time- piece had been taken on shore; and in this way the rate may be found. I should remark, that when the observation is made, the sun's altitude should not be found less than 8°, as late as 9h, or half past 9h, if it is in the morning, or about the same distance from noon, namely, half past two in the afternoon. This method is much superior to that where the sea horizon is used : indeed, it is very little inferior to that by the astronomical quad- rant. If a person is near an observatory, a rate may be given to a time-piece without moving it, merely by setting the pocket watch with the time-piece, and comparing it with the clock at the observatory several times a week. If a time-piece is brought on board without a rate, and it is not known how much it is fast or slow of Greenwich mean time, or if it has been let down while on board, (by which latter case I shall illustrate this point,) if the ship remains in the same place ten or fourteen days, a rate may be given it in the following manner.—Wind it up, and set it going as near Greenwich time as possible, in order that the difference may be little between Greenwich time and the time- piece. Suppose on September 26, 1797, I let my time-piece down, and set it going on the 27th, I take the altitudes at 9” 2' 16" by the time-piece; and I find my apparent time to be 2%. 53' 18" from noon; this subtracted from 12" (the observation being in the morning) leaves 9h 6'42". The equation taken from the Nautical Almanack for that time (9'13") being subtractive, leaves 8h 57'29"; this them is not the solar but the mean time. This time applied to 9h 2' 16", makes a difference of 4. 47%—If by this method you find the same difference every day, the time-piece is going at mean time; if the difference is greater, the time-piece is gaining the increase of difference every day : if the difference is less, the time-piece is losing the decrease of difference every day; because in this case, the time-piece shews a greater time than the mean time worked. If the time-piece had shewn a less time than thf mean time worked, the contrary would have been the case. The various uses of time-pieces can only be known to those who are in the habit of working and studying them. I believe I have sufficiently explained in what manner they are to be taken care of, and how their rates are to be found and managed; it only remains for me to explain their uses as far as my experience enables me. . The first and most essential is with the latitude, to ascertain the exact place T 1 M. T I N 1007 DICTIONARY OF MICHANICAL SCIENCE. of the ship, any day and several times a day, if necessary, in any part of the ocean when the sun is visible. Secondly, it has before been recommended to take altitudes about 9” or half past Qh in the morning, for finding the longitude. Having these, you will always be sure of the first of double altitudes, should there be any appearance of losing the meridional altitude by clouds or mists arising near noon. Thus, it may frequently happen that the navigator may have both longitude and latitude, when, without the use of a time-keeper, he might be disappoint- ed of both. Thirdly, it very often happens, particularly in high latitudes, that in a cloudy day the sun will shew itself on or about passing the meridian. Having a time-piece, you can tell, within a minute, when the sun is on the meridian : if an alti- tude can be caught about that time, even so far as ten minutes before or after the sun passes the meridian, that, altitude will give the latitude nearly; for in such latitude, particularly when the sun’s declination and the latitude are of different names, the sun's altitude alters very little in ten minutes on either side of noon. Fourthly, time-keepers are of great use in carrying on lunar distances from one day to another, so that a number of observations may be brought to one point. Altitudes being taken at the proper time by the time-piece, the apparent time thus obtained will answer for any lunar distances taken in the course of the succeeding twenty-four hours. . The method of car- rying on or deducing the time of taking the distances, to the time of taking altitudes for the longitude, may be illustrated as follows: Suppose that altitudes are taken for the longitude in the morning, and that several sets of lunar distances are observed in the afternoon. Take the elapsed time from observing the altitudes, to the time of each set of distances, and when the Greenwich time of the distances is brought out, subtract this elapsed time from the Greenwich time of each set: each remain- der will be the Greenwich time when the altitudes were taken, and will produce an observed longitude for that time; not for the time when the distances were observed. On the contrary, if lunar distances are observed before altitudes are taken for the apparent time, the elapsed time of each set must be added to the Greenwich time, to bring each set up to the time when the altitudes were taken. Observations of lunar distances also may be carried on from one time to another, so as to enable the observer, after having gained a number of sets on each side of the moon, to bring them all to one point by the time-piece, and get a mean of all the observations, which will give the true lon- gitude, if the observations are good.—This may be explained as follows: - Suppose, on January 20th, I observe six sets of lunar dis- tances; on the 21st, four more ; on the 23d, six sets more :— the 23d being the last day, when the distances are in the Nautical Almanack on that side the moon, I bring each set of distances to the time when the altitudes were taken on their respective days; I then take the difference of longitude shewn by the time-piece, on the 20th and 23d, at the time altitudes were taken on each day: I apply that difference to each set taken on the 20th. 'I do the same between the 21st and 23d ; each set will them be brought to the time when altitudes are taken on the 23d ; in all sixteen sets. The mean of these, if the observations are good, cannot be far from the truth, and the result may be brought to noon on that day by the log. But to be more certain of the observed longitude, I will carry on the sixteen sets as above directed, till I have obtained sixteen sets on the other side of the moon. These thirty-two sets being all carried on to the last day of observing their mean, I may con- sider as nearly the true longitude. By this method you may judge whether time-pieces have altered their rates or not; and may even give them a new rate, in the same way that you would have done in harbour, as I have before explained. Thus the lunar distances and time-piece may be made to go hand in hand with each other, to discover the ship's true longitude. A time-piece must be a very bad one indeed, if it will alter its rate to such a degree as to affect the observations while carry- ing on as I have described. A small'difference of rate they are all liable to, but this will not materially affect the observations. There is a small correction to be made at the time of the year when the daily difference of the equation is great. If the elapsed time between the altitudes, for the apparent time and the lunar distances be many hours, it will make an error of courses. some miles of longitude. This error, arising from the difference between mean and solar time, is not of much consequence at sea, or any where but in the observatory, where an astronomer is finding the exact longitude of his place by lunar distances, eclipses of Jupiter’s satellites, occultations, transits, &c. When there are more time-pieces on board a ship than one, the same apparent time may be made to answer, to find the longitude by them all; by comparing the one, by which the altitudes were taken, with all the rest. Take the elapsed time between ob- serving the altitudes and comparing ; if the comparison is made after the observation, subtract this elapsed time from the time shewn by the second time-piece, when the comparison is made ; the remainder is the time when the altitudes were taken, by the second time-piece: proceed then, as in common, to apply the error of its rate. The difference, then, between its time and the mean time at the ship, will be the longitude in time. For example: suppose altitudes were taken by No. 1, at 10° 50' 51"; No. 2 was compared with it at 13h 29' (by No. 1,) and shewed at that time 12h 44; 36". The elapsed time between observing altitudes and comparing, is 2h 38' 9"; which taken from 12" 44; 36" leaves 10h 6' 27", which is the time by No. 2, when the altitudes were taken. Suppose No. 2 to be slow of mean time at Greenwich 38' 40"; that, added to 10h 6' 27” gives 10h 45' 7", which is the mean time at Greenwich according to No. 2. Suppose the mean time at the ship to be 9h30'56", the difference between these mean times is 1h 14, 11", which turned into longitude, is 18° 32'45"; and as the mean time at Green- wich is greater than at the ship, the longitude is west. You may proceed in the same way with any other time-pieces on board.— In addition to the observations already made on time-pieces, I must advert to the very great importance of these instruments to officers charged with fleets or convoys, with respect to making short passages from one part of the world to another. A person who has a good time-piece will be enabled to steer straight This will shorten the distance much, and by that very circumstance will frequently enable him to get a fleet into port, before a shift of wind which might otherwise keep him out a long time. It will likewise give an officer a good chance of escaping the vigilance of a superior enemy; as he need not, according to the common system of navigation, run into the latitude of his port, in which his enemy may be cruising a few degrees of longitude to windward for him. He may run his longitude down thirty or forty leagues north or south of the port, as it may happen, till he is nearly or exactiy in the longi- tude of it; and then steer north or south to his destination, as the case requires. This mode of navigation might prevent the capture of many a valuable ship, and would certainly, by shortening the passages, in many instance cause a great, saving, not only to government, but to the merchant. TIMONEER, the helmsman or person who manages the helm to direct the ship’s course. - TIN. This metal has a fine white colour like silver, a slight disagreeable taste, and emits a peculiar smell when rubbed. Its specificgravity is 7.291. It is very malleable. Tin leaf or foil is about mºm part of an inch thick, and it might be reduced to half this thickness. It is very flexible, and produces a remark- able crackling noise when bended, and when heated 442 deg. it melts. When exposed to the air, it very soon loses its lustre, and assumes a grayish white colour, but undergoes no farther change, neither is it sensibly altered by being kept under cold water; but when the stream of water is made to pass over red- hot tin, it is decomposed, the tin is oxidated, and hydrogen gas is evolved. * TiN-Stone, an oar of tin which occurs in masses, in rounded pieces, and crystallized. These crystals are very irregular. Colour dark-brown; sometimes yellowish gray; and sometimes nearly white. Somewhat transparent when crystallized. Spe- cific gravity 6-9 to 6'97. Before the blow-pipe it decrepitates, and on charcoal is partly reduced. Tinges borax white. TINCTURE, is commonly understood to be a coloured infu- sion of any substance in alcohol. It is a preparation much em- ployed in pharmacy with many articles of the materia medica, particularly vegetable barks, aromatics of all kinds, and many of the resins and gum resins, which yield to alcohol, by infusion, that part of their substance in which most of the medicinai vir- tues reside. - a - 1008 T O G To p DICTIONARY OF MECHANICAL SCIENCE. ... TINNING. Tinning is the art of covering any metal with a thin coating of tin. Copper and iron are the metals most com- monly tinned, What are commonly called tin-plates or sheets, so much used for utensils of various kinds, are in fact iron plates coated with tin. The principal circumstance in the art of tinning is, to have the surfaces of the metal to be tinned perfectly clean and free from rust, and also that the tin may be perfectly metallic ; and not covered with any ashes or calx of tin. * - Tinning of Iron. When iron plates are to be tinned, they are first scoured, and then put into what is called a pickle, which is sulphuric acid diluted with water; this dissolves the rust or oxide that was left after scouring, and renders the surface per- fectly clean. They are then again washed and scoured. They are now dipped into a vessel full of melted tin, the surface of which is covered with fat or oil, to defend it from the action of the air. By this means, the iron, coming into contact with the melted tin in a perfectly metallic state, it comes out com- pletely coated. When a small quantity of iron only is to be tinned, it is heated, and the tin rubbed on with a piece of cloth or some tow, having first sprinkled the iron with some powder- ed resin, the use of which is to reduce the tin that may be oxi- dated. have in some degree the same effect, which is owing to their attraction for oxygen. - Tinning of Copper.—Sheets of copper may be tinned in the same manner as iron. Copper boilers, saucepans, and other kitchen utensils, are tinned after they are made. They are first scoured, then made hot, and the tin rubbed on as before with resin. Nothing ought to be used for this purpose but pure grain tin; but lead is frequently mixed with the tin, both to adulterate its quality, and make it lie on more easily, but it is a very pernicious practice, and ought to be severely reprobated. TITANIUM, a metal found in black sand, resembling gun- powder, in Cornwall. Its colour is orange red, and it has a good deal of lustre. As it has been only obtained in very small agglutinated grains, neither its hardness, specific gravity, nor malleability, has been ascertained. It is one of the most inſu- sible of metals, requiring a greater heat to melt it than can be produced by any method at present known. TITHES, are the tenth part of the increase yearly arising and accruing from the profits of lands, the stock upon lands, and the personal industry of the inhabitants. And hence they are usually divided into three kinds, praedial, mixed, and per- sonal. Praedial tithes are such as arise merely and immediate- ly from the ground, as grain of all sorts, hay, wood, fruits herbs; for a piece of land or ground being called in Latin praedium, whether it is arable, meadow, or pasture, the fruit or produce thereof is praedial, and consequently the tithe payable for such annual produce is called a praedial tithe. Mixed tithes are those which arise not immediately from the ground, but from things immediately nourished from the ground, as by means of cattle depastured thereupon, or otherwise nourished with the fruits; as colts, calves, lambs, chickens, milk, cheese, eggs. Personal tithes are such as arise from the labour and industry of man, employing himself in some personal work, artifice, or negotia- ation; being the tenth part of the clear gain, after charges deducted. Watts, c. 59. But this is seldom paid in England, except by especial custom. TITLE, in Law, denotes any right which a person has to the possession of a thing; or an authentic instrument, whereby he can prove his right. TOAD. See RANA. TOBACCO. Sec NICOTIANA. . - TODDY, a juice drawn from various kinds of palms, by cutting off such branches as nature intended to bear fruit, and receiving from the wound the sap designed for the nourishment of the future crop. This juice undergoes fermentation, and, with other ingredients, is used in the distillation of arrack. TOGA, a wide woollen gown or mantle, without sleeves, used among the Romans both by men and women. TOGETHER, in a nautical sense, the order given to the men, in the exercises of heaving, rowing, hauling, hoisting, &c. to act all in concert, or at the same time. TOGGEL, a small pin of wood, from four to six inches in Any inflammable substance, as oil for instance, will tremities, it is sometimes used instead of a hook in fixing a tackle, &c. In ships of war it is usual to fix toggels upon the running parts of the topsail sheets, the gears, &c. when pre- paring for action, in such manner that if the rope is shot away below, the toggel may stop the yard from coming down. This operation is called putting the sheets in the beckets. See the article Beckets. * TOKAY WINE, derives its name from a town or village in Hungary, where this delicious and costly liquor is produced. TOLERATION, in Religion, is the liberty granted under the protection of law, to those who dissent from the rites and con- stitution of an ecclesiastical establishment, permitting them to worship God without molestation, agreeably to the dictates of their consciences. Few subjects have generated more contro- versies than those to which toleration has given birth. TOLUIFERA, the balsam or tolu tree, a genus of plants of the class decandria and order monogynia. There is only one species, the balsamum. This balsam possesses the same ge- neral virtues with the balsam of Gilead, and that of Peru. It is, however, less heating and stimulating, and may therefore be employed with more safety. It has been chiefly used as a pectoral, and is said to be an efficacious corroborant in gleets and seminal weaknesses. ias in the syrupus tolutaus, tinctura tolutana, and syrupus balsamicus. .. TOMBAC, a metal composed of copper and arsenic. TON Weight, 20 hundred. - TONNAGE, a custom or impost due for merchandise brought or carried in tons from or to other nations, after a certain rate in every ton. TONNAGE, the same with BURt Hen, which article see. TONSURE, in Ecclesiastical History, a particular manner of shaving or clipping the hair of ecclesiastics or monks. TONTINE, a variable kind of life annuity, but generally so contrived as to be progressively increasing in amount. It is formed by nominating a certain number of lives within limited ages, who for each one hundred pounds or any other gross sum paid down, are to receive at first a specific annuity; but as any of the lives fail, their annuity is to be equally divided among those that remain, by which means those individuals who hap- pen to survive a considerable number of years, obtain a large augmentation of their annual receipt; and the longest liver of the whole (if there is no restriction to the contrary) gets, for the remainder of his life, the total sum which was paid at first to all the nominees. Tontines of this kind, if properly conduct- ed, are considered by some persons as affording an eligible opportunity of making some provision for children, as the no- mination of good healthy lives gives a good chance for survi- worship. It has several times been attempted to raise money on this species of annuity for the service of government, but it has never been found practicable to obtain any considerable sum in this way; on a smaller scale it has been adopted successfully, both in Great Britain and Ireland, for procuring the sums ne- cessary for building bridges, large inns or hotels, and other ex- pensive edifices. . - TOP, a sort of platform surrounding the lower-mast head, from which it projects on all sides like a scaffold. The prin- cipal intention of the top is to extend the top-mast shrouds so as to form a greater angle with the mast, and thereby give additional support to the latter. It is sustained by certain timbers fixed upon the bounds and cheeks of the masts, and called the trestle-trees and cross-trees. The top is also very convenient to contain the materials necessary for extending the small sails, and for fixing and repairing the rigging and machinery with greater expedition. In ships of war, the tops are furnished with swivels, musketry, and other fire-arms, and are guarded with a fence of hammocks in time of action. Here the top is used as a kind of redoubt, and is accordingly fortified for attack or defence, being furnished with swivels,...musketry, and other fire-arms, and guarded by a thick fence of corded hammocks. Finally, the top is employed as a place for looking out either in the day or night. Top-Armour, a rail about three feet high, extending the width of the top on the afterside, supported by stanehions, and - 3 * . equipped with a netting, and sometimes with painted canvass. length, and usually tapering from the middle towards the ex- - - - Top-Block. See the article Block. It is directed by the pharmacopoc- t T O R. T O U I009 DICTIONARY OF MECHANICAL SCIENCE. Top-Chain. See the article CHAIN. Top-Cloth, a large piece of canvass, used to cover the ham- mocks, which are lashed in the top when prepared for action. Top-Lantern, a large lantern placed in the after-part of a top in any ship where an admiral's flag or commodore's pendant is flying. Top-Mast, the second division of a mast, or that part next above the lower-mast. See the article MAST. Top-Gallant-Mast, the mast next above the top-mast, and is generally the uppermost mast. . - Top-Rope, a rope employed to sway up a top-mast or top- gallant-mast, in order to fix it in its place, or to lower it in tempestuous weather, or when it is no longer necessary. The top-rope passes through a block which is hooked on one side of the cap, and afterwards through a hole furnished with a sheave on the lower end of the top-mast; it is then brought. upwards on the other side of the mast, where it is fastened to an eye-bolt in the cap. To the lower end of the top-mast top- rope is fixed a tackle. See the article Top-TAcKLE. Top-Rope, is also the name of a rope used in swaying up or lowering down the top-gallant-yards. | Top-Sails, large sails extending across the top-masts by the top-sail yards above, and by the lower-yards beneath, being fastened to the former by earings and robands, and to the latter by means of the top-sail sheets, which passing through two great blocks fixed on its extremities, and from thence to two other blocks fixed on the inner part of the yard close by the mast, lead downwards to the deck. - Top-gallant-Sails, are extended above the top-sail-yards, in the same manner as the top-sails are extended above the lower- yards. See the article SAIL. Top-Tackle, a large tackle hooked to the lower end of the top-mast top-rope, and to the deck, in order to increase the me- chanical power in hoisting the top-mast. It is composed of two strong iron-bound double or triple blocks, the hooks of which work on a swivel. Laying Top, a cylindrical piece of wood, having three or four scores or notches on its surface, used in rope-making, and vary- ing in its size according to the thickness of the rope for which it is intended. TOPAZ. The name topaz has been restricted by Mr. Hauy to the stones called by mineralogists occidental ruby, topaz, and Sapphire; which, agreeing in their crystallization, and most of their properties, were arranged under one species by Mr. Rome de Lisle, The topaz is found in Saxony, Bohemia, Si- beria, and Brazil, mixed with other minerals in granite rocks. The Siberian and Brazil topaz, when heated, become positively electrified on one side and negatively on the other. It is infu- sible by the blow-pipe. The yellow topaz of Brazil becomes red when exposed to a strong heat in a crucible; that of Sax- ony becomes white by the same process. This shews us that the colouring matter of these two stones is diſſerent. TOPQGRAPHY, a description or draught of some particular place of small tract of land, as that of a city or town, manor or tenement, field, garden, house, castle, &c. such as surveyors set out in their plots, or make draughts of, for the information and satisfaction of the proprietors. TOPPING, the act of pulling one of the extremities of a yard higher than the other, by slackening one of the lifts and pulling up the opposite one, so as to place the yard at a greater or lesser distance obliquely with the mast. Top PING Lift, a large and strong tackle employed to suspend or top the outer end of a gaff, or of the boom of a cutter, brig, sloop, or schooner's main-sail. Top Men, persons stationed in the several tops to attend the taking in or setting of the upper sails. TORMENTOR, an instrument much used in tillage, some- times for breaking down the stiff clod, and at other times for skimming off the surface turf, that it may be prepared for being burnt. It bears in general appearance some resemblance to a harrow, only it is supported on wheels, and each tine is fur- nished with a hoe or share that enters and cuts up the ground. TORNADO, a sudden and vehement gust of wind from all points of the compass, frequent on the coast of Guinea. A tor. nado seems to partake much of the nature of a whirlwind, or perhaps of a water spout, but is more violent in its effects. It - 107. commences very suddenly, several clouds being previously drawn together, when a spout of wind proceeding from them strikes the ground in a round spot of a few rods or perches diameter, and proceeds thus half a mile or a mile. The prone- ness of its descent makes it rebound from the earth, throwing such things as are moveable before it, but some sideways or in a lateral direction from it. A vapour, mist, or rain, descends with it, by which the path of it is marked with wet. The fol- lowing is a description of one which happened a few years since at Leicester, about 50 miles from Boston in New England; it happened in July, on a hot day, about four o'clock in the after- noon. A few clouds having gathered westward and coming overhead, a sudden motion of their running together in a point being observed, immediately a spout of wind struck the ground at the west end of a house, and instantly carried it away with a negro man in it, who was afterwards found dead in the path of it. Two men, and a woman, by the breach of the floor, fell into the cellar; and one man was driven forcibly up into the chim- ney-corner. These were preserved, though much bruised ; they were wet with a vapour or mist, as were the remains of the floor, and the whole path of the spout. This wind raised boards, tim- bers, &c. A joist was found on one end, driven nearly three feet into the ground. The spout probably took it in its elevated state, and drove it forcibly down. The tornado moved with the celerity of a middling wind, and constantly declined in strength till it entirely ceased. TORRFD Zone, among geographers, denotes that tract of the earth lying upon the equator, and on each side as far the two tropics, or 23° 28′ of north and south latitude. The torrid zone was believed by the ancients to be uninhabitable, but is now well known to be even tolerable to the people of the colder climates, towards the north and south ; the excessive heat of the day being there tempered by the coldness of the night. TORTOISE SHELL, the shell of the testaceous animal called a tortoise ; used in inlaying, and in various other works, as for snuff-boxes, combs, &c. …” Toss (To) the Oars up, is to put them in a perpendicular direction, ready to let them all fall at once into the water, and is intended as a compliment to the passengers in the boat. TOUCAN, in Astronomy, a constellation of the southern he- misphere, consisting of eight small stars, and otherwise called Anser Americanus. - TOUCH, or Feeli NG, Sense of. The sense of feeling differs from the other senses in belonging to every part of the body, external or internal, to which nerves are distributed. The term touch is most correctly applied to the sensibility which is dif- fused over the surface of the body. Touch exists with the most exquisite degree of sensibility at the extremity of the fingers and thumbs, and in the lips. The sense of touch is thus very commodiously disposed, for the purpose of encompassing smaller bodies, and for adapting itself to the inequalities of larger ones. The sensations acquired by the sense of feeling are those of heat, hardness, solidity, roughness, dryness, mo- tion, distance, figures, &c. and all those corporeal figures which arise from a healthy or diseased state of the nerves, and the part of the body to which they belong. The pains of this sense are more numerous and vivid than those derived from any other sense; and therefore the relicts of them coalescing with one another, constitute the greatest share of our mental pains, that is, pains not immediately derived from sensation. On the other hand, its pleasures being faint and rare in com- parison with others, and particularly those of the taste, have but a small share in the formation of the mental pleasures. To Uch-Needle, among assayers, refiners, &c. little bars of gold, silver, and copper, combined together in all the different proportions and degrees of mixture ; the use of which is to dis- cover the degree of purity of any piece of gold or silver, by comparing the mark it leaves on the touchstone with those of the bars. TOUCH and Go, is spoken of a ship when under sail she rubs against the ground with her keel without much diminution of her velocity. TOUCHING, is the state of a ship's sails when they first begin to shiver with their edges in the direction of the wind. It is either occasioned by an alteration in the ship's course, or b a change of the wind. See the article FULL and BY. - 12 A - 1010 T R A • T. R. A DICTIONARY OF MECHANICAL SCIENCE. Touching At, implies the circumstance of stopping or an- choring occasionally at some intermediate port in the course of the voyage. g - - TOURMALINE, in Mineralogy, a species of siliceous earth, The thickest parts are opake ; the thin, more or less trans- arent. . . - TOURNIQUET, a machine or instrument employed in the practice of surgery to stop bleeding. . It can, however, only be applied to the limbs, and its use is only intended to be temporary. - Tow, (To) to draw a ship or boat forward in the water, by means of a rope attached to another vessel or boat, which ad- vances by the effort of rowing or sailing. Towing is either practised when a ship is disabled, and rendered incapable of carrying sail at sea; or when her sails are not fixed upon the masts, as in a harbour; or when they are deprived of their force of action by a cessation of the wind. When a ship of war is dismasted, or otherwise disabled from carrying sail at sea, she is usually towed by a cable reaching from her bow to another ship ahead. In a harbour, towing is practised by one or more boats, wherein all the force of the oars is exerted to make her advance. - To take a vessel in Tow, is sometimes a figurative expression for taking care of her. TOWING over Board, impiies the act of drawing any thing after a ship or boat when she is sailing or rowing, which has previously been on board that ship or boat. Tow-Line, a small hawser generally used to remove a ship from one part of a harbour or road to another by means of an- chors, capstans, &c. See the article WARPING. It is also em- ployed occasionally to moor a small vessel in a harbour conve- niently sheltered from the wind and sea. Tow Rope, a name given to any cable or other rope used in the exercise of towing, - TOWER, any high building raised above another, consisting of several stories, usually of a round form, though sometimes square or polygonal.; a fortress, a citadel. Towers are built for fortresses, prisons, &c. as the tower of the Bastile, which was destroyed by the inhabitants of Paris in 1789. TOXICODENDRON, the poisonwood. TRACHEOTOMY, in Surgery, is the operation of making an opening into the windpipe. TRACK of a Ship. See the article WAke. - TRACKING, the act of pulling any vessel or floating body along the stream of a canal or river, by means of a rope ex- tending from the vessel, &c. to an adjacent shore, and drawn along the banks of a river by men or horses. Whence TRAck Schuyt, a vessel employed to carry goods and passen- gers up and down the rivers and canals in Holland, and the countries bordering on the Baltic sea. - TRADE, the practice of exchanging goods, wares, money, bills, and other articles of value, with the view of advantage or profit. It is generally distinguished into foreign trade, or the export and import of commodities to and from other countries. and the internal or home trade, or that which is carried on with- in the country; which two branches, however, are rather distinct in appearance than reality; for a very considerable portion of the internal trade arising from manufactures carried on to sup- ply foreign markets, could not subsist without foreign commerce ; while a large part of the returns for manufactures sent abroad, being articles for consumption or raw materials, which are con- verted to use in the different manufactures, depends upon our 1nternal trade; so that the one supports the other, and by their mutual connexion and dependence, the foreign and the domestic trade of Great Britain have risen together to their present unparalleled height. TRADE, implies the constant destination of any particular merchant vessel, as the Lisbon trade, West India trade, &c. TRADE Winds, certain regular winds blowing within or near the tropics, and being either periodical or perpetual. Thus, in the Indian ocean they blow alternately from two opposite points of the compass, and in the Atlantic ocean eontinne almost with- out intermission in one direction; see the article WIND. TRAGACANTH, GUM, or, as some call it, gum adragant, or gum dragon, is the produce of the above and some other shrubs. The gum is brought to us in long and slender pieces, of a flatted low-bell, both in shape, size, and meshes. figure more or less, and these not straight, or rarely so, but com- monly twisted and contorted various ways, so as to resemble worms. We sometimes meet with it, like the other vegetable exudations, in roundish drops, but these are much more rare. It is moderately heavy, of a firm consistence, and, properly speak- ing, very tough rather than hard ; and is extremely difficult to powder, unless first carefully dried, and the mortar and pestle kept dry. Its natural colour is a pale white, and in the clean- est pieces it is something transparent. It is often, however, met with of a brownish tinge, and of other colours still more opake. It has no smell and very little taste, but what it has is disagree- able. Taken into the mouth, it does not grow clammy and stick to the teeth, as the gum arabic does, but melts into a kind of very soft mucilage. It dissolves in water but slowly, and communicates its mucilaginous quality to a great quantity of that fluid. It is by no means soluble in oily or spirituous liquors, nor is it inflammable. It is brought to us from the island of Crete, and from several parts of Asia. It is to be chosen in long twisted pieces, of a whitish colour, very clear, and free from all other colours; the brown, and particularly the black, are wholly to be rejected. +. TRAGEDY. See PoETRY. - º TRAIN, the hinder part of a gun carriage; also a line of gunpowder or other combustible materials, forming a commu- nication with any body intended to be set on fire or exploded. TRAIN Tackle, a combination of pulleys which during action is locked to an eye-bolt in the train of the carriage, and to a ring- bolt in the deck. Its use is to prevent the gun from running out of the port whilst loading. TRAJECTORY, a term often used, generally for the path of any body moving, either in a void, or in a medium that resists its motion, or even for any curve passing through a given num- ber of points. - TRAMMELS, in Mechanics, an instrument used by artificers for drawing ovals upon boards, &c. One part of it consists of a cross with two grooves at right angles; the other is a beam carrying two pins, which slide in those grooves, and also the describing pencil. - TRAMMEL NET, is a long met where with to take fowl by night in champaign countries, much like the net used for the To use it, they spread it on the ground, so that the nether or further end, fitted with small plummets, may lie loose thereon; then the other part being borne up by men placed at the fore ends, it is thus trail- ed along the ground. At each side are carried great blazing lights, by which the birds are raised, and as they rise under the net they are taken. TRANSCENDENTAL, or TRANscendent, something ele- wated or raised above other things, which passes and transcends the nature of other inferior things, Transcendental quantities, among geometricians, are indeterminate ones, or such as cannot be fixed, or expressed by any constant equation; such are all transcendental curves which cannot be defined by any algebraic equation, or which, when expressed by an equation, one of the terms thereof is a variable quantity." TRANSFUSION of Blood. The experiments of Dr. Blum- dell and other experienced physiologists had long since de- monstrated the practicability of transmitting blood from one living body to another; but it is, at length, to Dr. Blundell’s application of it to the human body, and to his unwearied zeal and physiological knowledge, that the profession is indebted for positive data upon which it can be undertaken with the best hopes of saving life under circumstances of appalling, but, alas ! frequent occurrence. The value of the operation having been lately demonstrated by several successful cases, there seemed to be wanting but one requisite for extending the benefit of this invaluable discovery into the remotest regions of professional influence. The extreme caution practised and inculcated by Dr. Blundell, shewing the danger of admitting air into the blood-vessels, sufficiently attests the necessity for an appara- tus by which the operation may be conducted without incur- ring this risk. This has been supplied by an appendage which Mr. Read has added to his surgical syringe, and of which Dr. Blundell has been pleased to express his approbation. It consists of a double apparatus, the one receiving the blood into a tubulated funnel, the other transmitting it from the vein g T R. A. * T R A 1011 DICTIONARY OF MECHANIC A. L SCIENCE. of one person into that of another, without atmospheric commu- nication. In neither case is it necessary to lay bare the vein, as has been usually done, the venous pipes being constructed to pass freely into the opening made by the lancet. The trans- fusion appendages are so small, that the parts for the two modes of operating scarcely occupy the space of a common scalpel case, and, if fitted up with the stonnach and enema appa- ratus, will increase the size in a very trifling degree. Directions for the Operation with Read's Apparatus.-The metallic stem to be first screwed into the stand, the funnel next upon the stem, and, thirdly, the perpendicular arm of the latter to be inserted firmly into the extremity of the syringe by a rota- tory twist. The flexible tube to be then screwed to the lateral }}| º ſº Māºffſ!"S$ 2 * 2% \ * branch of the syringe, and the silver pipe inserted into the socket at the other extremity. The apparatus being thus ad- justed, the surgeon should pump a few ounces of water through it, keeping the point of the pipe immersed in the fluid, when, if he observes any bubbles of air rise, he must fix the different parts closer until no air is admitted. The whole should now be plunged into a basin of warm water for a minute or two, and being placed betwixt the person who supplies the blood and the patient, a ligature is to be put around the arm, and the blood drawn by a free incision into the funnel. An opening being made into a vein of the patient's arm, (the limb kept steady and unmoved, to preserve the relative position of the internal | and external openings, as well as to prevent the cellular tissue from slipping over the orifice in the vein) the operator gives three or four short strokes of the piston, which expels the small quantity of air contained in the tube, without occasioning the expenditure of more than a few drachms of blood. The pipe is to be immediately introduced into the vein, and the shield pressed against the surface of the arm by the fingers of an assistant, whilst the operator proceeds to throw in the blood by jets. , Dr. Blundell recommends the piston to be drawn up only one-fourth its length, which will be found to throw in about a drachm of blood at a stroke. The surface of the blood in the fun- nel must not be allowed to sink below a line drawn in the lower part of its interior, lest air should be admitted with the fluid. To convey blood from one person to another without atmo- spheric communication, the tube with the cylindrical socket, being armed with a silver pipe, is to be inserted into the extre- mity of the syringe, and the pipe passed into a vein (in the direction of the fingers) of the right arm of the person who is to furnish it, and whose arm is to be tied up as in the former case. A few strokes of the piston (as before directed) throws out a Small quantity of blood, and expels the air in the tubes, when the pipe of the tube screwed to the side-branch of the syringe is to be passed into a vein (in the direction of the heart) of the left arm of the patient, and the quantity of blood injected may be measured by counting the strokes of the piston, reckoning one drachm at each jet. The patient should recline upon the back, with the left arm near the edge of the bed; the person losing the blood should sit on a very low seat closé to the bed- side and with his back to the operator, who stands with the pump in his left hand sufficiently distant from both parties to keep the tubes as nearly straight as possible, one nearly horizontai, the other almost perpendicular. The syringe should be very clean when used, and the assistants are required to keep the pipes firmly in the veins, during the operation. TRANSIT, in Astronomy, signifies the passage of any plan- net just by or over a fixed star, or the Sun ; and of the moon in partieular covering or moving over any planet. - TRANSITION, in Music, the softening a distinct interval by the introduction of intermediate sounds. In harmony, transition is the changing the genus or mode in a sensible but regular Inanner. - . TRANSiTION, Rocks, are particularly distinguished as being the lowest in which fossil remains of animals or vegetables are found; they may be regarded as ancient records imprinted with the natural history of the first inhabitants of the globe. TRANSMUTATION, in Geometry, denotes the reduction or change of one figure or body into another of the same area or solidity, but of a different form ; as, a triangle into a square, a pyramid into a parallelopiped, &c. In the higher geometry, transmutation is used for the converting a figure into another of the same kind and order, whose respective dimensions in an equation admit of the same tangents, &c. In alchemy and me- tallurgy, transmutation signifies the turning of one metal into another, so as entirely to change its nature. - TRANSOMS, certain beams or timbers extended across the sternpost of a ship, to fortify her after-part, and give it the figure most suitable to the service for which she is calculated. Helm-port TRANSoM, that which is at the head of the stern- post, and forms the upper part of the gun-room ports. Wing TRANso M, the next below, and forming the lower-part. Deck TRANSo M, that whereon all the lower deck planks are rabbeted. The 1st, 2nd, 3d, transoms, &c. are respectively below the preceding. . TRANsomi Knees, are strong pieces of curved timber, which connect the ship's quarter to the transoms, being bolted to the latter and to the after timbers. See KNEES. TRANSOM, among Builders, denotes the piece that is framed across a double light window. TRANsom, among Mathematicians, signifies the vane of a cross- staff, or a square whereon it slides, &c. TRANSPARENCY, a quality in certain bodies, by which they give passage to the rays of light. TRANSPORT.—See SHIP. * TRANspoRT Office, a department under government directed by commissioners, who charter vessels and appoint officers for the conveying troops to or from this country ; they are also to provide accommodation and provision for all prisoners of war, to regulate their exchange by cartel, &c. To TRANspoRT a Ship, is to move her by means of hawsers, anchors, &c. from one part of a harbour to another. TRANSPORTATION, thc act of conveying or , carrying a thing from one place to another. TRANSPORTAtion, is a kind of punishment, or more properly an alleviation or commutation of punishment, for criminals convicted of felony ; who for the first offence, unless it is an extraordinary one, are generally transported to the plantations, (at present to New South Wales), there to bear hard labour for a term of years, within which if they return, they are exe- cuted without further trial than identifying their persons. ... TRANSPOSITION, in Algebra, the bringing any term Öf an equation over to the other side. TRANSUBSTANTIATION, in Theology, the conversion or change of the substance of the bread and wine in the eucharist, into the body and blood of Jesus Christ, which the Romish church holds is wrought by the consecration of the priest. This is a main point in the Romish religion, and is rejected by the Pro- estants, the former maintaining the transubstantiation to be real, the latter only figurative; interpreting the text, Hoc est corpus meum, “this signifies my body;” but the council of Trent stood up strenuously for the literal sense of the verb est, and say expressly that in transubstantiation the body and blood of our Lord Jesus Christ are truly, really, and substantially, un- der the species of bread and wine. TRANSVERSE Muscles, in Anatomy, are certain muscles arising from the transverse processes of the vertebrae of the loins. * TRAP, is derived from the Swedish word trappa, a stair. It is applied, in geology, chiefly to such rocks, as are frequently seen rising in regular order above one another in the form of stairs, as basalt. The chief trap rocks are horne blende, which 1012 T. R. E. T. R. A. DICTIONARY OF MECHANICAL SCIENCE. is subdivided into granular hornblende, and hornblende slate. There is also hornblende mixed with felspar, of which green- stone and greenstone slate are common subdivisions. Also hornblende mixed with mica. The transition trap consists of greenstone and amygdaloed.—Trap also signifies a snare, con- trived to catch men, animals, birds, &c. TRAPEZIUM, in Geometry, a plane figure contained under four unequal right lines. TRAVELLER, one or more iron thimbles, with a rope spliced round them, sometimes forming a kind of tail, but more gene- rally a species of grommet, and used on various occasions. TRAVELLING Back Stays, are so denominated from their having a traveller upon the top-mast, which slides down as the top-sail is lowered, thereby confining the principal support of the back-stay to that part of the mast immediately above the top-sail-yard. See BAckstay. TRAvellino Martingale, a similar contrivance adapted to a martingale, to support the jib-boom in that particular part where the jib-tack is fixed. See MARTING ALE. TRAVERSE, or TRANsverse, in general denotes some- thing that goes athwart another ; that is, crosses, aud cuts it obliquely. TRAverse, in Law, signifies sometimes to deny, sometimes to overthrow or undo a thing, or to put one to prove some matter; much used in answer to bills in chancery : or it is that which the defendant pleads or says in bar, to avoid the plain- tiff's bill either by confessing and avoiding, or by denying and traversing the material part thereof. TRAverse an Indictment, is to take issue upon the chief mat- ter, and to contradict or deny some point of it. A traverse must be always made to the substantial part of the title. Where an act may indifferently be intended to be at one day or another, there the day is not traversable. TRAVERSE SAILING, is used when a ship having set sail from one port towards another, whose course and distance from the port sailed from is given or known, is by reason of contrary winds, or other accidents, forced to shift and sail on several courses, which are to be brought into one course, to learn after so many turnings and windings the true course and distance made from the place sailed from, and the true point or place where the ship is; that so, the wind coming fair, it may be known how afterwards to shape a course for the place intended. This may be performed geometrically two ways; the first by drawing new meridians through the extremity of every course, parallel to the first meridian, or north and south line, at first made, and setting off every course at sixty, as if it were a question in plain sailing; you may also let fall perpendiculars to every new meridian, from the point that the ship sailed to Chinese Tread Mill. wheel is exactly similar to a common water-wheel; the tread- boards upon its circumference are, however, of considerable length, so as to allow sufficient standing room for a row of from upon that course; by which you have the course, distance, dif- ference of latitude, and departure, to every course. To work a traverse by the tables of difference of latitude and departure, make a little table with six columns; the first for the course, the second for the distance, the third for the northing, the fourth for the southing, the fifth for the easting, and the sixth for the westing. Then find the difference of the latitude and the departure to every course, and set them in their proper columns; as where the course is northerly, set the difference of latitude under northing, or in the north column; and where the course is southerly, set the difference of latitude in the south column. Again, where the column is easterly, set the departure in the east column, and when westerly set it in the west column; then adding up each column by itself, subtract the north and south columns, the less from the greater, the remainder is the north- ing or southing made good; then have you the difference of latitude and the departure, given to find the course and dis- tance. This is the principal use those tables are intended for, and the way of working a traverse hereby is equal to the best for exactness, and superior in point of expedition. TRAverse Board, a thin circular piece of board, marked with all the points of the compass, and having eight holes bored in each, and eight small pegs hanging from the centre of the board. It is used to determine the different courses run by a ship during the period of a watch, which is performed by sticking one peg into the point on which the ship has run each half hour. This implement is particularly useful in light and vari- able winds. TRA verse Table, is the same with a table of difference of latitude and departure, being only the difference of latitude and departure ready calculated to every degree, point, half point, and quarter point of the quadrant; and for any distance under one hundred miles, though it may conveniently serve for greater distances, by taking their halves, thirds, fourths, &c. and doubling, tripling, and quadrupling, &c. the difference of latitude and departure found to those parts of the distance. This table is one of the most necessary things a navigator has occasion for ; for by it he can readily deduce all his courses and distances run in the space of twenty-four hours, into one course and distance; whence the latitude he is in, and his departure from the meridian, may be found. TREADMILL. This is an invention of the Chinese, and is used to raise water for the irrigation of the fields. Culprits are condemned to this labour, the mode of working is very sim- ple, and will be seen by looking at the figure. The treadmill lately introduced into the prisons in Great Britain is of a more complicated construction. It is the invention of Mr. Cubitt, of Ipswich. The engraving exhibits that erected at Brixton. This English Tread Mill. - -- --- - - - ten to twenty persons upon the wheel. Their weight, the first moving power of the machine, produces the greatest effect when applied upon the circumference of the wheel at or near the level T R. E. T R I DICTIONARY OF MECHANI CAL SCIENC. E. 1013 of its axle; to secure therefore this mechanical advantage, a screen of boards is fixed up in an inclined position above the wheel, in order to prevent the prisoners from climbing or step- ping up higher than the level required. A hand rail is seen fixed upon this screen, by holding which they retain their upright position upon the revolving wheel; the nearest side of which is exposed to view in the plate, in order to represent its cylindri- cal form much more distinctly than could otherwise have been dome. In the original, however, both sides are closely boarded up, so that the prisoners have no access to the interior of the wheel, and all risk of injury whatever is prevented.--By means of steps, the gang of prisoners ascend at one end ; and when the requisite number range themselves upon the wheel, it com- mences its revolutions. The eſfort then to every individual is simply that of ascending an endless flight of steps, their com- bined weight acting upon every successive stepping board, pre- cisely as a stream of water upon the float boards of a water- wheel. During this operation each prisoner gradually advances from the end at which he mounted towards the opposite end of the wheel, from whence the last man taking his turn descends for rest (see the engraving), another prisoner immediately mount- ing as before, to fill up the number required, without stopping the machine. The interval of rest may then be proportioned to each man by regulating the number of those required to work the wheel with the whole number of the gang ; thus, if twenty out of twenty-four are obliged to be upon the wheel, it will give to each man intervals of rest amounting to twelve minutes in every hour of labour. Again, by varying the number of men upon the wheel, or the work inside the mill, so as to increase or diminish its velocity, the degree of hard labour or exercise to the prisoner may also be regulated. At Brixton, the diame- ter of the wheel being five feet, and revolving twice in a minute, the space stepped over by each man is 2193 feet, or 731 yards per hour. At page 324 the reader will find a description and engraving of another species of treadmill. TREASON, in Law, is divided into high treason and petty treason. High treason is defined to be an offence committed against the security of the king or kingdom, whether it be by imagination, word, or deed ; as, to compass or imagine the death of the king, queen, or prince, or to deflower the king's wife, or his eldest daughter unmarried ; or his eldest son’s wife; or levy war against the king in his realm, adhere to his enemies, counter- feit his great seal, privy seal, or money, or wittingly to bring false money into his realm counterfeited like the money of Eng- land, and utter the same, to kill the king's chancellor, treasurer justices of either bench ; justices in eyre, of assize, or of oyer and terminer, being in their place doing his office, forging the king's sign manual or privy signet, privy seal or foreign coin current here, or diminishing or impairing current money. In this case of treason, a man shall be hanged, drawn, and quarter- ed, and forfeit his lands and goods to the king. 25 Ed. III. TREASON, Petit. Whenever a wife murders her husband, a ser- vant his master or mistress, or an ecclesiastic a prelate, or to whom he owes obedience, every one of these offences is petit treason.—As every petit treason implies a mnrder, it follows, that the mere killing of a husband, master, or prelate, is not always petit treason; for if there are not such circumstances in the case of killing one of these persons as would have made it murder in the case of killing any other person, it does not amount to this offence. There can be no accessary in high treason. And it seems to be always agreed, that what would have made a man an accessary before the fact in any other felony, makes him a principal in high treason. TREASURE TRove, is where any money or coin, gold, sil- ver, plate, or bullion, is hidden in the earth, or other private place, the owner being unknown; in which case the treasure belongs to the king, or some other who claims by the king's grant or by prescription. But if he that hid it is known or afterwards found out, the owner and not the king is entitled to it. If it is found in the sea or upon the earth, it does not belong to the king, but to the finder if no owner appear. TREASURER, an officer to whom the treasure of a prince or corporation is committed to be kept, and duly disposed of. TREATY, a covenant between several nations, or the several articles or conditions stipulated and agreed upon between Sovereign powers. - 107. TREE, the first and largest of the vegetable tribe, consisting of a trunk, out of which spring forth branches and leaves. TREE-NAIILS, certain long cylindrical wooden pins, em- ployed to connect the planks of the ship's side and bottom to the corresponding timbers, and are justly esteemed superior to spike nails or bolts, which are liable to rust and koosen; the thickness of the tree-nails is usually proportioned to the length of the ship, allowing one inch to every hundred feet. TREFOIL, in Architecture, is the ornamenting of an arch in a particular manner. In Agriculture, trefoil is a valuable grass very generally cultivated. TRENCHES, in Fortification, are ditches cut by the besieg- ers, that they may approach more securely to the place attack- ed, whence they are also called lines of approach. The tail of the trench is the place where it was begun, and its head is the place where it ends. The trenches are usually begun or opened in the night time ; sometimes within musket-shot, and some- times within half or whole cannon shot of the place. They are carried on in winding lines, nearly parallel to the works of the fortress, so as not to be in the view of the enemy, nor exposed to the enemy’s shot. The workmen employed in the trenches are always supported by a number of troops, to defend them against the Sallies of the besieged : the pioneers sometimes work on their knees, and are usually covered with mantlets or faucissons; and the men who support them lie flat on their faces, in order to avoid the enemy’s shot. TREND, (TO) to incline, speaking of a coast, as, “The land trends to the south-west.” * TREPAN, in Surgery, a circular saw, by means of which the operation called trepanning is performed. It bears a strong resemblance to a whimble or centre bit, and is worked in an almost similar manner. TRESPASS, is any transgression of the law, under treason, felony, or misprision of either. - TRESTLE TRees, two strong bars of timber fixed horizon- tally on the opposite sides of the lower-mast head, to support the frame of the top and the weight of the top-mast. TRET, in Commerce, an allowance made for the waste or the dirt that may be mixed with any commodity, which is always four pounds in every hundred and four pounds weight. TRIAL, the proceeding of a court of law when the parties are at issue, such as the examination of witnesses, &c. to enable the court, deliberately weighing the evidence given on both sides, to draw a true conclusion, and administer justice accordingly, TRIANGLE, in Geometry, a figure bounded or contained by three lines or sides, and which consequently has three angles from whence the figure takes its name. TRIANGULA, The Triangles. The poets feign that Jupiter assigned the island of Sicily a place in the heavens, under the figure of a triangle. Hevelius has added to Jove's labour by introducing another triangle in this asterism. The old triangle is also said to owe its origin to the Delta in Egypt; both of these figures are easily distinguished by the stars on which they are formed, as well as their position relatively to Andromeda, Ce- pheus, and Aries.— Boundaries and Contents. North by Andro- meda, west by Andromeda and Pisces, south by Aries, and east by Musca and Perseus. There are sixteen stars in this constel- lation, three of which are of the fourth magnitude and the remainder of inferior magnitudes. TRIANGULAR CoMP Asses, are such as have three legs or feet whereby to take off any triangle at once, much used in the con- struction of maps, globes, &c. TRIANGULAR Numbers, are a kind of polygonal numbers, being the sums of arithmetical progressions which have 1 for the common difference of their terms. Thus, from these arithmeti- cals, 1, 2, 3, 4, 5, 6, are formed the triangular numbers, 1, 3, 6, 10, 15, 21, or the third column of the arithmetical triangle above mentioned. * - TRIANGULAR Canon, the tables of artificial sines, tangents, secants, &c. - g TRIANGULAR Quadrant, is a sector furnished with a loose piece whereby to make it an equilateral triangle. The calendar is graduated thereon with the sun’s place, declination, and other useful lines; and by the help of a string and a plummet, and the divisions graduated on the loose piece, it may be made to serve for a quadrant. 12 B • 1014 T R f T R I DICTIONARY OF MECHANICAL scIENCE. TRIANGULUM Australe, the Southern Trianglé, one of the constellations situated on the Antarctic circle, contains five stars, viz. one of the 2d magnitude, two of the 3d, &c. TRIBOMETER, an instrument invented for lestimating the friction of metals. - TRICE, (To) to haul or tie up by means of a small rope or line. . - . - TRICHECHUS, WALRUs, a genus of quadrupeds of the order bruta. It is principally found in the high latitudes of the northern ocean. These animals are gregarious, and are often seen upon floating masses of ice in immense numbers, the greater part sleeping, but some always on the watch to give no- tice of approaching danger. They are harmless when not pro- voked, but some accounts represent them as highly formidable , in a state of irritation, the efforts of many being combined against the enemy, and fastening with their teeth against the boats, to make holes in them, or draw them to the bottom. Others represent them as less agitated by the fury of passion, and as inclined more to flight than revenge; adding, that they are terri- fied by the slightest flash, and even the pointing of a musket will drive them in a moment out of sight. Their tusks serve the purposes of aiding their movements upon the ice, into which they are stuck, and on which they thus secure their hold, and sometimes drag on their unwieldy bodies. The tusks are con- vertible to the purposes of ivory, and these animals are destroy- ed for the profit derived parly from these tusks, but principally for the sake of their oil, of which a full-grown walrus will yield a butt. The skin may be manufactured into a very strong lea- ther. The affection between the female and its young one, for it has seldom more than one at a birth, is such, that they are said never to separate, and that when one is killed, the survivor re- fuses to quit the dead body, and is considered by the hunter as his secure prey. The walrus has been called, with little resem- blance to justify the name, the sea-horse ; it is more similar to a cow—but most of all to a seal. The whale-tailed manati, inha- bits the seas between Kamptschatka and America. These ani- mals live in families, generally consisting of a male and female, and two young ones of different ages, and the attachment of | the male to the female is so great, that he will defend her when attacked to the last extremity : and if she happens to be de- stroyed and dragged to the shore, he will swim for some days off the fatal and detested spot. The manati approaches very nearly to the cete tribe, and its feet are little more than pecto- ral fins. It attains the immense length of twenty-seven feet, and the weight of four tons. In winter it is extremely Jean, and its ribs may be distinctly numbered. It will, when pierced with the harpoon, sometimes adhere to rocks with its feet with uncommon tenacity, and when forced from them by a cord drawn by thirty men or more, is found to have left part of the skin of the feet behind. When any individual is harpooned, others are stated to swim to its aid, endeavouring some to overturn the boat, others to break the cord, and others again by blows with their tails striving to dislodge the harpoon. Their sounds resem- ble the snorting of a horse. They are never seen on land. TRICING LINE, a small cord generally passing through a block or thimble, and used to hoist up any object to a higher station, in order to render it less inconvenient, such are the tricing lines of the yard tackles, &c. TRICK, the same as spell with regard to steering the ship. See the article SPELL. TRIFOLIUM, TREFoil, or Clover, a genus of plants of the class diadelphia, and order decandria, and in the natural sys- tem ranging under the 32d order papilionaceae. The flowers are generally in round heads; the pod is scarcely longer than the calyx, univalve, not opening, deciduous. The leaves are three together: 51 species. TRIGONOMETRY. The business of this important science is to find the angles, where the sides are given ; and the sides of their respective ratios, when the angles are given; and to find sides and angles, when sides and angles are partly given. To effect this, it is necessary not only that the peripheries of circles, but also certain right lines in and about circles, be supposed divided into certain numbers of parts. The ancients, feeling the necessity of such a pre-division, portioned the cir- cles into 360 equal parts, which they called degrees; each degree was again divided into 60 equal parts, called minutes; and each minute comprised 60 equal parts called seconds. The moderns have improved upon this division by the addition of a nonius, or vernier, which may be carried to any extent, but is usually limited to decimating the seconds; noting each tenth part thereof. It would have been found a considerable conve- nience in mathematics, if the circle had been divided into cen- tesimal parts, particularly in trigonometrical operations; thus making every quadrant to consist of 100 degrees, each degree of 100 minutes, and each minute of 100 seconds; there can, indeed, be no doubt that all the arithmetical calculations re- lating to the periphery, as well as to the secants, signs, tan- gents, radii, chords, and complements, would by this reform- ation have been simplified. See the words Mensuration, ACCESSIBLE DISTANCE, Heights and D1st ANces, &c. TRILLION, in Arithmetic, a billion of billions. . TRIM, the state or disposition of the ballast, cargo, masts, &c. by which a ship is best equipped for the several purposes of navigation. - - The TRIM of the Hold, implies the arrangement of the mate- rials therein, by which a ship is either brought by the head or. stern, or depressed in the water to a sufficient depth to carry sail well, and advance rapidly. As the stowage of the hold, or the disposition of the several articles of the cargo, considerably affects the ship’s motion and stability, it will be necessary to give a general idea of the action that supports it, and the re- action of the fluid on the floating body. - First, we may consider the whole weight of any body as united in its centre of gravity: so that if it were suspended by a line fastened to this centre, the line would hang in a perpen- dicular position, as directed through the centre of gravity to the centre of the earth. A body which floats in a fluid is not, how- ever, supported by its centre of gravity, but by the compression of the surrounding filaments of water; and each of these being considered as infinitely small, will act upon a very minute por- tion of the surface of the floating body with regard to the specific gravity, and conform to a principle applicable to all fluids, in proportion to the height of these filaments, viz. that the weight of a column of any ſluid will be in proportion to the specific gra- vity of the fluid and the height of the column multiplied by its base. But as heavy bodies endeavour by their gravity to approach the centre of the earth in a vertical line passing through their centres, so the pressure of fluids endeavours to carry bodies in a vertical line tending from the centre of the earth towards the surface, and passing through the centre of gravity of the submer- ged part which forces them towards the surface. So in any Submerged body at rest, these two opposite forces coincide in the same vertical, acting in a direction quite contrary to each other. According to this theory, it appears that the stability or trim of a ship chiefly depends upon her construction, as considering the bottom to be homogeneous. This, however, can only happen when her cargo consists of the same materials throughout, as with corn, salt, or any species bestowed in bulk, and when her hold is entirely filled: for if the ship has not suffi- cient breadth to resist the effort of the wind upon her sails, or if she is built too high or too sharp in the floor, her gravity will be too high, and she will be very crank, i. e. apt to overturn. But as the stiffness of a ship, or quality to carry sail without. damage of overturning, depends very much on the stowage of the hold, the centre of gravity may thereby be considerably lowered, by which her stability will be increased in proportion. It is a general maxim among mariners, that a ship will not carry sufficient sail till she is laden so deep that the surface of the water may glance on her extreme breadth amid-ships. She. must therefore have a great deal of weight, as ballast, &c. to bring her to this situation, which is called a good sailing trim. With regard to the quality, weight, and stowage of the ballast, there are also several circumstances to be particularly consi- dered. If the centre of gravity be placed too high, the ship will be rendered incapable of carrying a sufficient quantity of sail, and if it be placed too low, she will be in danger of rolling away her masts. When it is placed too far forward, the vessel will pitch and labour heavily ; and when too far aft, she will occa- sionally be exposed to the dangerous circumstance of a poop- ing sea. These extremes being carefully avoided, it remains to proportion the contents of every part of the hold to its capacity, . and to place the lightest materials uppermost. T R () T R U. DictionARY of MECHANICAL scIENCE. 1015 TaiM of the Masts, denotes their position with regard to the ship and to each other, whether near or distant, far forward or much aft, erect or raking. - e - a TRIM of the Sails, signifies the general arrangement which is best calculated to accelerate the ship's course according to the direction of the wind. See the articles CLOSE-HAULED, LARGE SAILING, TACKING, &c. - - If a ship were always to sail before the wind, it would be a very simple operation to trim the sails; for nothing more would be required than to dispose them so as to receive the greatest possible effort of the wind, which is evidently performed by arranging them at right angles with its direction... But when the current of wind acts more directly upon the ship's side, it necessarily falls more obliquely on the surface of the sails, so as to diminish their effort to push the ship forward, and to aug- ment their tendency to make her incline to one side. Hence we may conclude, that an increase of the wind, when accompa- nied with a variation unfavourable to the ship's course, will by no means augment her velocity; because the force pre- viously employed to push her forward will afterwards, operate to overturn her, and because this impression renders it neces- sary to reduce the quantity of sail; the effort of which is further diminished by the obliquity of the action of the wind upon its surface. By this theory it appears, that the effect of the wind to advance the ship, decreases in proportion to its obliquity with any sail upon which it operates. - TriM the Boat. See Boat. TRIMMED SHARP, the situation of a ship's sails in a scant wind. - TRINITY HOUSE, a kind of college at Deptford, belonging to a company or corporation of seamen, who by the king's char- ter have power to take cognizance of those persons who de- stroy sea-marks, and to get reparation of such damages, and to take care of other things belonging to navigation. At present, many in the first rank of society are members of that community. The master, wardens, and assistants of the Trinity House, may set up beacons and marks for the sea, in such places near the coast or forelands as to them shall seem meet. By a statute of Queen Elizabeth, no steeple, trees, or other things standing as sea-marks, shall be taken away or cut down, upon pain, that every person guilty of such offence shall forfeit 100l. and if the person offending be not possessed of the value, he shall be deemed convicted of outlawry. TRIP, a phrase implying an outward-bound voyage, particu- larly in the coasting navigation. It also denotes a single board in plying to windward. - TRIPLICATE RATIo, the ratio of cubes to one another. TRIPOLI, a mineral found sometimes in an earthy form, but more generally indurated. Its texture is earthy. TRIPPING, the movement by which an anchor is loosened from the bottom, either by its cable or buoy-rope. - TRIPPING-Line, a small rope serving to unrig the lower-top- gallant-yard-arm, when in the act of striking or lowering it down upon deck. TRISECTION, or TRIssection, the dividing a thing into three. The term is chiefly used in geometry for the division of an angle into three equal parts. The trisection of an angle geometrically, is one of those great problems whose solution has been so much sought by mathematicians for these two thousand years, being in this respect on a footing with the quadrature of the circle, and the duplicature of the cube angle. - TRITICUM, WHEAT, a genus of plants of the class triandria, and order digynia, and in the natural system ranging under the fourth order gramina. TROCHILUS, Humming Bird, a genus of birds belonging to the order of pica. There are sixty-five species, none of which are natives of Britain: they are all remarkable for the beauty of their colours, and most of them for the smallness of their size, though some are eight or nine inches in length. They are divided into two families, viz. those with crooked bills, and those with straight bills. - TRONAGE, the mayor and commonalty of the city of Lon- don are ordained keepers of the beams and weights for weigh- ing merchants’ commodities, with power to assign clerks, port- 'ers, &c. of the great beam and balance, which weighing of goods and wares is called tromage. - - kinds used in Britain. TROPHY, TRoPIEUM, among the ancients, a pile or heap of arms of a vanquished enemy, raised by the conqueror in the most eminent part of the field of battle. The trophies were usually dedicated to some of the gods, especially Jupiter. The name of the deity to whom they were inscribed was generally mentioned, as was that also of the conqueror. TROPICS, two imaginary lines upon the globe parallel to the equator, and at 23% degrees distance on each side of it ; ºrm the boundaries of the sun's declination north and SOUlth. ... TROUGH, a name given to the hollow or interval between two waves, which resembles a broad and deep trench perpetually fluctuating. As the setting of the sea is always produced by the wind, it is evident that the waves, and consequently the trough or hollow space between them, will be at right angles with the direction of the wind; hence a ship rolls heaviest when she lies in the trough of the sea. TROUT, a very valuable river fish, too well known to need description. TROVER, is the remedy prescribed by the law, where any person is in the possession of the property of another, which he unlawfully detains. - TROY WEIGHT, one of the most ancient of the different The pound English troy contains 12 ounces, or 5760 grains. - TROY WEIGHT, Scots, was established by James VI. in the year 1618, who enacted that only one weight should be used in Scotland, viz. the French troy stone of 16 pounds, and 16 ounces in the pound. The pound contains 7600 grains; and is equal to 17 oz. 6 dr. avoirdupois. The cwt. or 112 lb. avoirdupois, contains, only 103 lb. 23 oz. of this weight, though generally reckoned equal to 104 lb. Though prohibited by the articles of union, it is still used in weighing iron, hemp, flax, most Dutch and Baltic goods, meal, butcher's meat, unwrought pewter and lead, and some other articles. • TRUCE, in War, denotes a suspension of arms, or a cessa- tion of hostilities between two armies, in order to settle articles of peace, bury the dead, or the like. • TRUCKS, pieces of wood of various forms, and used for dif- ferent puposes, as TRUCKs of a Gun Carriage. See the article CARRIAge. TRUCKS of the Mast-Head, circular pieces of wood, fixed as a cap on the top-gallant-mast heads. They are generally fur- nished with two or more small pulleys through which the pen- dant and signal-halliards are reeved. They are also called a COTIT.S. TRUCKs of the Parrels, are spherical pieces of wood, having a hole through them, in which is inserted the rope of the parrel. See the article PARREL. - TRUCKs of the Flag Staff, are pieces resembling an oblate spheroid. - TRUCKS of the Shrouds, or Seizing Trucks, are pieces some- thing resembling those of the parrels, except that they are scored round the outside, to receive a seizing, and are fixed to the shrouds, in order to lead the running rigging and prevent it from hanging. The intention of these is to guide the sailors to the particular rope which, especially in the night, might otherwise be mistaken for some other of the same size. TRUFFLES, in Natural History, a kind of subterraneous puff-ball, being a species of fungi, which grows under the sur- face of the earth. TRUMPET, the loudest of all portable wind instruments, and consisting of a folded tube generally made of brass, and sometimes of silver. - TRUMPET Hearing, is an instrument to assist the hearing of persons who are deaf. Instruments of this kind are formed of tubes, with a wide mouth, and terminating in a small canal, which is applied to the ear. The form of these instruments evi- dently shews how they conduce to assist the hearing, for the greater quantity of the weak and languid pulses of the air being received and collected by the large end of the tube, are reflect- ed to the small end, where they are collected and condensed; thence entering the ear in this condensed state, they strike the tympanum with a greater force than they could naturally have done from the ear alone. Hence it appears that a speaking trumpet may be applied to the purpose of a hearing trumpet 1016 T. U N T R Y E}} GTIONARY OF MECHANICAL SCIENCE. by turning the wind end towards the sound, and the narrow end to the ear. * * TRUMPET, Marine, a kind of monochord, consisting of three tables which form its triangular body. It has a very narrow neck, with one thick string; mounted on a bridge, which is firm on one side, and tremulous on the other. It is struck with a bow by the right hand, while the thumb of the left is pressed on the string. - TRUMPET, Speaking, is a tube of considerable length, viz, from 6 feet to 12, and even more, used for speaking with, to make the voice heard to a greater distance. In a trumpet of this kind the sound in one direction is supposed to be increased, not so much by its being prevented from spreading all around, as by the reflection from the sides of the trumpet. The figure best suited for the speaking trumpet is that which is generated by the rotation of a parabola about a line parallel to the axis. TRUNCATED, in general, is an appellation given to such things as have, or seem to have, their points cut off. TRUNDLE, in rural economy, a sort of truck having two handles at one extremity, and two low wheels at the other, by which means it is trundled before the person using it. In con- veying articles of great weight, but of small bulk, this simple machine is found very convenient. TRUNDLe Shot, an iron bar called a shot, about Seventeen inches long, and sharp-pointed at the ends, having a round ball of lead cast upon it, at a hand’s breadth from the extremities. TRUNKS, FIRE, wooden funnels fixed in fire-ships, under the shrouds, to convey the flames to the masts, rigging, and sails. TRUNNIONS, the two knobs or arms which project from the opposite side of a piece of artillery, and serve to support it in the carriage. TRUSS, is also used for a sort of bandage or ligature made of steel, or the like matter, wherewith to keep up the parts in those who have hernias or ruptures. A bale of goods is also called a truss. - TRUss of Flowers, is used by florists to signify many flowers growing together on the head of a stalk, as in the cowslip, auricula, &c. TRUss, among Mariners, signifies a machine employed to pull a lower yard close to its mast, and retain it firmly in that position. . As the truss is generally used instead of a parrel, it is rarely employed except in flying top-gallant sails, which are never furnished with parrels. It is no other than a ring or traveller, which encircles the mast, and has a rope fastened to its after-part, leading downward to the top or decks; by means of which the truss may be straitened or slackened at pleasure. The halliards of the top-gallant sails being passed through this ring, and the sail being hoisted up to its utmost extent, it is evident that the yard will be drawn close to the main-mast by pulling down the truss close to the upper part of the sail; for without the truss the sail and its yard would be blown from the mast so as to swing about by the action of the wind and the rolling of the vessel, unless the yard were hoisted close up to the pulley wherein the halliards run, which seldom is the case in flying top-gallant-sails, because they are usually much shal- lower than those which are fixed or standing. TRUSs Tackle, a combination of pulleys fixed to the end of the truss pendants to bowse them taught. TRUST, is a right to receive profits of land, and to dispose of the land in equity. And one holding the possession, and disposing of it at his will and pleasure, are signs of trust. TRUSTEE, one who has an estate or money put or trusted in his hands for the use of another. - TRYING, the situation in which a ship lies nearly in the trough or hollow of the sea in a tempest, or it is the act of lying to in a storm, which may be performed under any of the courses reeved, if requisite, or even under bare poles, the helm being lasheda-lee. In trying, as well as in scudding, the sails are always reduced in proportion to the increase of the storm. Thus, in the former state a ship may lie by the wind under a whole main-sail, a whole fore-sail, or a whole mizzen; or under any of those sails, when diminished by the reef or balance. As the least possible quantity of sail used in scudding are the goose-wings of the fore-sail, so in trying, the smallest portion is generally the mizzen Stay-sail, or main stay-sail; and, in either state, if the storm be the sea phrase, under bare poles. dually narrower from the lower deck upwards. books, this narrowing of a ship from the extreme breadth upwards , is called housing-in. - excessive, she may lie with all the sails furled, or, according to º - The intent of spreading a sail at this time is to keep the ship more steady, and by press- ing her side down in the water, to prevent her from rolling vio- lently, and also to turn her towards the direction of the wind, so that the shock of the waves may fall more obliquely on her flank than when she lies along the trough of the sea. While she remains in this situation, the helm is fastened close to the lee-side, or, in the sea language, hard a-lee, to prevent her as much as possible from falling off. But as the ship is not then kept in equilibrium by the effort of her sails, which at other times counterbalance each other at the head and stern, she is moved by a slow but continual vibration, which turns her head alternately to windward and to leeward, forming an angle of three or four points in the interval. That part where she stops in approaching the direction of the wind, is called her coming to, and the contrary excess of the angle to leeward is termed her falling off. Thus, suppose the wind northerly, and a ship trying with her starboard side to windward; if, in turning her head towards the source of the wind she arrives at N. W. A. N. or N. 39° W. and then declines to the leeward as far as W. § S or S. 84° W. the former will be called her coming to, and the latter her falling off. TRY-SAIL, a sail used by cutters, luggers, sloops, &c. in lieu of their main-sail during a storm. Try Sail, is also the name of a sail on board of a snow, which see. TUB, is a kind of measure to denote the quantity of various things. A tub of tea, is about 60 pounds; a tub of camphor, from 56 to 80 pounds; and a tub of vermilion, from 300 to 400 cwt. - TUB, MATCH, the half of a cask, having notches sawn in Its edge, wherein the lighted matches are placed during action, the bottom being covered with water to extinguish any sparks which may fall from the match. *. Topsail Halliard TUBs, similar to half casks, in which the topsail halliards are coiled. Grog TUB, a half cask set apart for mixing the daily allowance of spirits with water, prior to its being served out to the ship's company. - TUBE, in general, pipe, conduit, or canal; a cylinder, hol- low withinside, either of lead, iron, wood, glass, or other mat- ter, for the air, or some other fluid, to have a free passage or conveyance through. Tu Be, in Astronomy, is sometimes used for a telescope, or, more properly, for that part into which the lenses are fitted, and by which they are directed and used. TUBER, or TUBERCLE, a kind of round turgid root, in the form of a knob or turnip. The plants which produce such roots are hence denominated tuberous. Tuber is an old Latin name for any sort of excrescence, its derivation being from tumeo, to swell. It is applied to several things of the fungus tribe. TUCK, that part of a ship where the ends of the bottom planks are collected together, immediately under the stem or COUnter. A Square TUCK, is terminated above by the wing transom, and below and on each side by the fashion-pieces. TUFAS, beds of lime deposited on vegetables, which by their destruction give great lightness and porousness to the mass. TUISCO, a fabulous deity among the northern nations, from whom our Tuesday derives its name, that being the day on which his worship was more particularly celebrated. TULIPA, TULIP, a genus of plants, of the class hexandria and order monogynia, and in the natural system ranging under the 10th order coronariae. - TUMBLING Home, that part of a ship's side which falls inward above the extreme breadth, so as to make the ship gra- In all old sea- TUMCUR, or TUMoR, in Medicine and Surgery, a preterna- tural rising or hard swelling on any part of the body. TUN, or Ton, originally signifies a large vessel or cask, of an oblong form, biggest in the middle, and diminishing towards its two ends, girt about with hoops, and used for stowing seve- ral kinds of merchandise, for convenience of carriage; as, brandy, oil, sugar, skins, hats, &c. This word is also used for T U R. T Y. P. DICTIONARY OF MECHANIGAL scIENCE. 1017 certain vessels of extraordinary bigness, serving to keep wine for several years. x º TUN, is also a certain measure for liquids, as wine, oil, &c. TUN, is also a certain weight whereby the burdens of ships, &c. are estimated. TUNE, or Tone, in Music, that property of sounds whereby they come under the relation of acute and grave to one another. TUNGSTEN, a mineral found in Sweden, of an opaque white colour and great weight; whence its name tungsten or ponder- ous stone. This ore was analyzed by Scheele, who found that it was composed of lime and a peculiar earthy-like substance, which from his properties he called tungstic acid. The basis of the acid was found to contain a metal which was named tungsten, and which was obtained from the acid mixed with charcoal. - TUNICA, a kind of waistcoat or under garments, in use among the Romans. - TUNNEL, a large subterraneous arch driven through a hill for the passage of boats in a canal continued through the Saſſ) 6. - - TURBAN, the head dress of most of the eastern and Maho- metan nations. In the adjustment of the turban much taste is displayed. In the folds, the dimensions, and colours of the turban, the rank and dignity of the wearer may frequently be known. The Emirs, who trace their descent from Mahomet, have green turbans, while the others are ordinarily red, with a white sash. Persons of distinction have frequent changes of turbans. The turban of the grand signor is as large as a bushel, adorned with three plumes of feathers, and enriched with diamonds and precious stones. It is so highly respected by the Turks, that they scarcely presume to touch it. That of the grand vizir has two plumes, superior in size to those of any inferior officer. TURBOT, a well-known fish, uniformly held in high estima- tion. - - TURDUS, the Thrush, in Natural History, a genus of birds of the order passeres. * TURF, the greensward, or surface of grass land. © . TURMERIC, the Indian Saffrom. It is now cultivated in England, and in the materia medica is officially known. It is also much used in yellow dyes. TURN of the Tide, the change from ebb to flood, or the contrary. . . TURN of a Rope, the applying it once round any body, as a timber-head, &c. in order to hold on. TURN in the Hawse. See HAWS e. To TURN in, a sea phrase implying to go to bed, as To TURN Out, is to get up or out of bed. To TURN in a Dead Eye or Heart, to seize the end of a shroud or stay, &c. securely round it. To TURN over Men, to discharge them out of one ship into another. s To TURN the Hands up, to call the ship's company upon deck for any particular purpose. . . TURNAMENT, or Tour NAMENT, a martial sport or exercise which the ancient cavaliers used to perform, to shew their bra- very and address. - t - TURNING. See LATH E. TURNING to WINDw ARD, that operation in sailing, wherein a ship endeavours to make a progress against the direction of the wind, by a compound course inclined to the place of her destination; this is otherwise called plying or beating to wind- ward. See the articles Be ATING and TACKING. TURNIP, a nutritious bulb-rooted plant, of which there are many sorts in cultivation by the gardeners and farmers. TURNPIKE, a gate set up across a road, watched by an officer for the purpose, in order to stop travellers, waggons, coaches, &c. to take toll of them towards repairing or keeping the roads in repair. . - TURPENTINE, a transparent sort of resinous juice, ſlowing either naturally or by incision from several unctuous trees, such as the larch, pine, fir, &c. Turpentine is too generally known to require a particular description, either of its nature or In Ultimer OUIS UI S6S. - TURRETS, among the Romans, were a kind of moveable towers, driven by men towards the place of attack, and con-. 108. taining soldiers, who were secure from the weapons of their assailants. *- TUTENAG. This name is given in India to the metal zinc. It is sometimes applied to denote a white metallic compound, brought from China, called also Chinese copper, the art of making which is not known in Europe. Three ingredients of this com- pound may be discovered by analysis; namely, copper, zinc, and iron. Some of the Chinese white copper is said to be merely copper and arsenic. • . TUTOR, one chosen to instruct children. - TUTTY, an argillaceous ore of zinc, found in Persia, formed on cylindrical moulds into tubulous pieces, like the bark of a tree, and baked to a moderate hardness. TWICE-LAID CoRDAG e, is made of cart rigging, which being untwisted, is again wrought up into ropes sufficiently strong for numerous purposes. TWILIGHT, denotes that faint light which is reflected by means of the atmosphere before the sun rises, and after he sets. TWINE, a kind of strong thread used in sail-making, and is of two kinds, extra for sewing the seams, and ordinary for the bolt-ropes. - TYCHONIC SYSTEM or HYPothesis, an order or arrange- ment of the heavenly bodies, of an intermediate nature between the Copernican and Ptolemaic, or participating alike of them both. This system liad its name and original from Tycho Brahe: a nobleman of Denmark, who lived in the latter part of the last century. This philosopher, though he approved of the Co- pernican system, yet could not reconcile himself to the motion of the earth; and being, on the other hand convinced the Pto- lemaic scheme could not be true, he contrived one different from either. In this the earth has no motion allowed it but the am- nual. The Tychonic system then supposed the earth in the centre of the system, that is, of the firmament of stars, and also of the orbits of the sun and moon; but at the same time it made the sun the centre of the planetary motions, viz. of the orbits of Mercury, Venus, Mars, Jupiter, and Saturn. Thus, the sun, with all its planets, was made to revolve about the earth once a year, to solve the phenomena arising from the annual motion; and every twenty-four hours, to account for those of the diurnal motion. TYE, a sort of runner or thick rope, used to transmit the effort of a tackle to any yard or gaff; which extends the upper part of a sail. The tye is either passed through a block fixed to the mast-head, and afterwards through another block attached to the yard or gaff, and returns to the mast-head, or the end of it is simply passed over a sheave in the mast-head, and then fastened to the said yard or gaff. - - TYMPAN, among Printers, is a double frame, belonging to the press, covered with parchment, on which the blank sheets are laid in order to receive the impression. TYMPANUM, or TYMPAN, in Mechanics, a kind of wheel placed round an axis or cylindrical beam, on the top of which are two levers or fixed staves, for the more easy turning the axis, in order to raise a weight required. TYPE, among Printers, is a metallic composition cast into letters, and is a term of synonymous import. See PRINTING. Type-METAL. The basis of type metal for printers is lead, and the principal article used in communicating hardness is antimony, to which copper and brass in various proportions are added. The properties of a good type metal are, that it should run freely into the mould, and possess hardness without being excessively brittle. The smaller letters are made of a harder composition than those of a larger size. . It does not appear that our type founders are in possession of a good composition for this purpose. The principal defect of their composition appears to be that the metals do not uniformly unite. . In a piece of casting performed at one of our principal founderies, the thickness of which was two inches, one side was hard and brittle when scraped, and the other side, consisting of nearly half the piece, was soft like lead. The transition from soft to hard was sudden, not gradual. If a parcel of letter of the same size and casting be examined, some of them are brittle and hard, and resist the knife, but others may be bent and cut into shavings. It may easily be imagined that the duration and neatness of these types must considerably vary. . . TYPOGRAPHY. See PRINTING, * , 12 C I018 U N G, DICTIONARY OF MECHANICAL science. U U, or V, the twentieth letter of our alphabet. In numerals V stands, for five; and with a dash added at top, thus V, it signifies five thousand. In abbreviations, amongst the Romans, V. A. stood for veterani assignati; W. B. viro bono; W. B. A. viri boni arbitratu ; V. B. F. vir bonae fidei ; V. C. vir consula- ris; W. C. C. F. vale, conjux charissime, feliciter; W. D. D. voto dedicatur; W. G. verbi gratia; Vir. We. virgo vestalis; VL. videlicit; W. N. Quinto monarum. - U, as a contraction expresses urbs or urbe. ULLAGE of A CASK, in Gauging, is what it wants of being full. ULMUS, the Elm. Elms are forest trees well known in almost every part of England. There are several species, of which, however, only three, the common elm, wych hazel, or broad-leaved elm, and Dutch elm, grow in this country without cultivation. They are easily distinguishable, even by a com- mon observer, from most other forest trees, by their leaves being rough, and doubly serrated at the edge. ULTIMATE RATIOS. -introduced what he called the method of prime and ultimate ratios, the foundation of which is contained in the first lemma of the first book of the Principia. UMBELLIFEROUS PLANTs, are such as have their tops branched and spread out like an umbrella, on each little sub- division of which there is growing a small flower; such are fen- nel, dill, &c. - .” UMBER, or GRAYLING, (Salmo Thymallus,) is a fish of the salmon tribe, distinguished by having several longitudinal streaks upon its body, the first dorsal fin nearer the head than the ventral fins, the upper jaw longer than the lower one, the side nearly straight, and the tail forked. A fish of this species was caught lately in the Severn which weighed five pounds. The umber inhabits the clear and rapid streams of Europe and Siberia. These fish are so much esteemed in some parts of the continent, that they are exclusively reserved for the tables of the mobility. They are fattest in the antumn, but are best in season during the winter, particularly when the weather is cold; and they cannot be dressed too soon after they are caught. Many of the old medical writers strongly recommended umber as a wholesome fish for sick persons: they also stated that an oil prepared from its fat would obliterate freckles and other spots on the skin. By the Laplanders the intestines are frequently employed as a substitute for rennet, -to coagulate the milk of the rein-deer when used for the making of cheese. These fish are in great esteem by anglers on account of their vivacity, the eagerness with which they rise at a bait, and their rapid motions through the water. They lurk close all the winter, and begin to be very active in April and May, about which time they deposit their spawn. UMBRELLA, a well-known shade from the sun, or guard from the rain, formed by stretching silk, cotton, oil cloth, or other material, in a dome-like form over whalebone, and so constructed that it may be either spread or-contracted, as cir- cumstances may require. In Europe these conveniences have not been long in use. They were introduced from the East, where they have been known from time immemorial, but in a less elegant form than they have assumed since their importa- tion among the western nations. UNDECAGON, a polygon of eleven sides. UNDULATORY Motion, is applied to denote a motion in any fluid, by which its parts are agitated like the waves of the Sea, and is particularly applied to the motion of the air in the propagation of sound. NEVEN NUMBER, or Odd Number, divided into two equal integral parts. UNGULA, is the bottom part cut off by a plane passing obliquely through the base of a cone or cylinder, being thus called from its resemblance to the ungula or hoof of a horse, &c. that which cannot be UNGULA, among Surgeons, a sort of hooked instrument, used to extract a dead foetus out of the womb. To avoid both the tediousness of the ancients and the inaccuracy of the moderns, Sir Isaac Newton UNICIA, the 12th part of a thing. UNICIAE, the same as co-efficient. UNICORN. See MoMoCEROs. . . UNIT, or UNITY, is the representation of any thing consi- dered individually, without regard to the parts of which it is composed. - UNITARIANS, those Christians who believe in and worship one only self-existent God—the Father of Jesus Christ, in oppo- sition to those who, besides the Father, worship his Son Jesus, and the Holy Ghost, and who are therefore called Trinitarians. The Unitarians are often called Socinians; but the Socinians ' were not Unitarians, because they paid divine worship to the Son of God. UNITAS FRATRUM, or UNIten BRETHREN, a name dis- tinguishing those Christians who are frequently called Hern- huters abroad, and Moravians at home. UNIVERSALISTS, those who hold that all future punish- ment is designed for correction, and that consequently all ra- tional beings will be ultimately rendered happy by the God of love and mercy. - UNIVERSE, a collective term signifying the assemblage of heaven and earth, with all things in and upon them. UNLACING, the act of loosening and taking off the bonnet of a sail from its principal part. UNMOORING, reducing a ship to the state of riding by a single anchor and cable, after she has been moored and fastened by two or more cables. See the articles ANcholt and Moor. UNREEVING, the act of withdrawing or taking out a rope from any block, thimble, dead-eye, &c. through which it had formerly passed. See the article Reeve. UNRIGGING, depriving a ship of her standing and running rigging. UNSHIPPING, removing any piece of timber or wood from the place in which it was fitted, as, “unship the capstan bars,” “unship your oars.” UN SLINGING, to take off slings, which see. UPPER-DECK, the highest of those decks which are con- tinued throughout the whole length of a ship. UPPER Works, a general name given to all that part of a ship which is above the surface of the water when she is properly balanced for a sea voyage. - UPRIGHT, the situation wherein the opposite sides of a ship are equally elevated above the surface of the water, or when she neither inclines to the right nor left, with regard to the vertical position of her stem and stern post. URANIBURGH, the name given to the celebrated observa- tory of Tycho Brahe, founded by him in the little island of Weenen in the Sound. - URANIUM, a mineral found in Saxony, partly in a pure and partly in a mixed state. There are two varieties of these ; the first of a blackish colour, quite opaque, and tolerably hard, and with a specific gravity of about 7-5. The second is dis- tinguished by a finer black colour, with here and there a red- dish cast; by a stronger lustre, not unlike that of pit coal; by an inferior hardness, and by a shade of green, which tinges its black colour when it is reduced to powder. Uranium is of a dark gray colour; internally it is somewhat inclined to brown. URANUS. Hersch EL, or GeoRGIUM SIDUs, the name of the new planet discovered by Dr. Herschel the 13th March, 1781. See Ast RonoMY * - URCHIN, THe, or Hedge-Hog, is a small British quadru- ped, the upper parts of which are covered with spines, each about an inch long, and the under parts with hair. These animals are of considerable utility in several points of view. If kept, and allowed to run about rooms that are infested with leeches, cockroaches, or crickets, they will destroy the whole of them. Some persons imagine that they will devour mice, but this wants authentication. A hedge-hog, which was kept at the Angel Inn, at Felton, Northumberland, was tamed, and employed as a turnspit, and is said to have performed this U R N Us U DICTIONARY OF MECHANICAL scIENCE. 1619 duty in every respect as well as a dog of that name. The flesh of this animal is occasionally used as food, and is said to be very delicate eating. The skin, which was frequently em- ployed by the ancients as a clothes’ brush, is now used by farmers in some parts of the continent to put on the muzzles of calves which they are about to wean, that the cow may not permit them to suck. Several of the old writers have related accounts of very extraordinary, and at the same time very absurd, medical effects from different parts of this animal. Hedge-hogs frequent most commonly the bottoms of dry ditches, where they have shelter and concealment under bushes, fern, and grass. They sleep in the day-time, and are awake during the night, when they run abroad in search of worms, snails, insects, and other food. Few creatures can be more inoffen- When attacked, they defend themselves by rolling into a globular form, and opposing on all sides a spinous surface. There is a motion, but it is apparently unfounded, that hedge- hogs suck the milk of cows whilst lying in the fields asleep. UREA, the constituent and characteristic matter of urine, may be obtained by the following process: evaporate by a gen- tle heat a quantity of human urine, voided six or eight hours after a meal, till it is reduced to the consistence of a thick sy- rup. In this state, when put by to cool, it concretes into a crystalline mass. Pour at different times upon this mass four times its weight of alcohol, and apply a gentle heat; a great part of the mass will be dissolved, and there will remain only a number of saline substances; pour the alcohol solution into a retort, and distil by the heat of a sand-bath till the liquid, after boiling some time, is reduced to the consistence of a thick syrup. The whole of the alcohol is now separated, and what remains in the retort crystallizes as it cools. These crystal consist of the substance known by the name of urea. - URIC ACID. Uric or lithic acid was discovered by Scheele in 1776. It is the most common constituent of urinary calculi, and exists also in human urine. It has a brown colour; is hard, and crystallizes into small scales. It has neither, taste nor smell, is insoluble in cold water, but soluble in 360 parts of boiling water. URINE. The properties of urine vary considerably, accord- ing to the constitution and health of the body, and the period when it is voided after taking food. The urine of a healthy person is of a light orange colour, and uniformly transparent. It has a slightly aromatic odour, in some degree resembling that of violets. It has a slightly acrid saline bitter taste. The specific gravity varies from 1,005 to 1,033. The aromatic odour, which leaves it as it cools, is succeeded by what is called the urinous smell, which latter is converted to another, and finally to an alkalime odour. Urine converts the tincture of turnsol into a green colour, from which it is concluded that it contains an acid. No less than thirty different substances have been detected in urine by chemical analysis ; viz. a great quantity of salts, acids, ammonia, &c. Urine is much disposed to spontaneous decomposition. The time when this process commences, and the rapidity of the changes which take place, depend on the quantity of the gela- tine and albumen. When the proportion of these substances is considerable, the decomposition is very rapid. This is owing to the great number of substances, and the united force of their attractions overcoming the existing affinities of the different compounds of which fresh urine consists, and especially to the facility with which urea is decomposed. This substance is converted during putrefaction into ammonia, carbonic acid, and acetic acid. Hence the smell of ammonia is always recognized while urine is undergoing these changes. Part of the gelatine is deposited in a flaky form, mixed with mucilage. Ammonia combines with phosphoric acid, and the phosphate of lime is precipitated. It combines also with phosphate of magnesia, and forms a triple salt. The other acids, the urie, benzoic, the acetic, and carbonic acids, are all saturated with ammonia. URN, a kind of vase of a roundish form, but biggest in the middle, like our common pitchers. In ancient times they were much in use among most mations, to preserve the ashes of the dead, to contain liquids used at sacrifices, and to hold the lots upon which the destiny of events depended. At present they are known and valued only as ornaments, or vestiges of antiquity. - - - URSA MINOR, or CYNosur A, the Little Bear, according to the poetry of the skies, represents Arcas, the son of Calista, who was placed by Jupiter in the heavens under the figure of a bear. This constellation embraces the pole of the world, and is easily distinguished by seven stars in the same form, but in a contrary position to those of the Wain, in the Great Bear. Boundaries and Contents.-West and north by Draco, east by Camelopardalis, and south by Cassiopeia and Perseus. It extends from the North Pole to the Arctic Circle, and contains twenty-four stars, viz. one of the second magnitude, two of the third, four of the fourth, &c. - URSA MAJoR, the Great Bear, is said to be Calisto, an atten- dant of Diana, the goddess of hunting. Calisto was changed into a bear by Juno, and placed in the heavens by Jupiter. Another account, however, makes Ursa Major to be Arcas, the son of Jupiter and Calisto. Every one knows the story of Lycaon, king of Arcadia, being changed into a wolf, for kiſſing | his grandson Arcas, and setting him before Jupiter, to try the divinity of the father of gods and king of men. The ancients, it is said, represented the constellations of the Bears, each under the form of a waggon drawn by a team of horses. Ursa Major is well known to the country people at this day by the title of Charles's Wain; in some places it is called the Plough, an agricultural machine, which it certainly resembles. . Boundaries and Contents. North by Camelopardalis and Draco, east by Canes Venatici, south by Leo Minor, and west by Lynx and Camelopardalis. - URSUS, the Bear, in Natural History, a genus of mamma- lia, of the order ferae. There are ten species:-The brown bear, a native of Europe and Asia; the American bear, with a long pointed nose; the Polar bear, completely white and very much larger than the common or brown bear; the glutton, the wol- Verene, the racoon, and the common badger, found in almost all the temperate regions both of Europe and Asia, living in subterranean habitations, which its feet are admirably adapted for preparing. Its food consists of fruits and roots, frogs and insects; and the resemblance of its teeth to those of beasts of prey, makes it probable that it destroys lambs and larger ani- mals, which it is stated to do: in a domestic state it prefers raw flesh to every other species of food. It will attack bee- hives, to obtain the honey contained in them. It sleeps much ; passes the winter, or the greater part of it, in its burrowed re- sidence, in a state of lethargy and torpor; and in summer pro- duces generally three young ones at a birth. These animals are inoffensive in their manners; reluctant to attack, but well prepared by nature for defence, which they conduct with an alertness, intrepidity, and perseverance, truly admirable. To afford a spectacle of these qualities to the populace of seve- ral countries, the badger is often baited with dogs, which from the looseness of the badger's skin, and the coarseness of its hair, are prevented sometimes from penetrating to its flesh with their teeth, and, almost always, from so fastening him by their bite as to preclude his turning in various directions for their annoy- all C6. USE, is a trust and confidence reposed in another who is tenant of the land, that he shall dispose of the land according to the intention of him to whose use it is granted, and suffer him to take the profits. USES AND Customs of THE SEA, certain general principles, which compose the basis of marine jurisprudence, and regulate the affairs of commerce and navigation. USURPATION, an injurious appropriation for any given time of the rights or property that justly belongs to another. USURY, the exacting of a larger interest upon money than by law is allowed. The statute 12 Anne, c. 16, enacts, that no person upon any contract which shall be made, shall take for loan of any money, wares, &c. above the value of 5l. for the forbearance of 100l. for a year; and all bonds and assurances for the payment of any money to be lent upon usury, whereupon or whereby there shall be reserved or taken above five pounds in the hundred, shall be void; and every person who shall reeeive by means of any corrupt bargain, loan, exchange, shift, or interest, of any wares or other things, or by any deceitful way, for forbearing, or giving day of payment for one year, for their money or other things, above 5l. for 100l. for a year, shall forfeit } treble the value of the moneys or other things lent. 1020 W. A. C. DICTIONARY OF MECHANICAL SCIENCE. W. WAcation, in Law, is the whole time betwixt the end of one term and the beginning of another. This word is also applied to the time from the death of a bishop, or other spiritual person, till the bishopric or dignity is supplied with another. VACCINATION. Cow-pock inoculation. Inoculation with the vaccine virus, for the purpose of securing against the infec- tion of the small-pox. - VACUUM, in Philosophy, denotes a space empty or devoid of all matter or body. VACUUM ENGINE, BRowN's. Though this engine does not seem to have answered the expectations of its projectors; we very freely admit its description. Its principle is simply this: the formation of a vacuum in a cylinder by the combustion of hydrogen gas;–and that our readers may better comprehend the process by which this is done, and the power thereby ob- tained, we will first of all quote the inventor's own words. & A a. º Q º - - o n /* e - 7 f. \ - - * E={- | || 2n &lº----- - - k - ºnlºn * ſºlº l º º º \l º |_ {k | * > - - |||||||||}| |||| | || |: ** | |- ºl | | - | | |- - - - º |||| | º His sºlº | | - º | | - º || || || / || Lºſ |º || ||Nºs | || - | --- º- | W º | |- I Nº. | | Tººl | /. N - - % N |% N | sº d | * * zi | º 3|| || | º N Tººlſ ºr | N Tli N |*|| | N | || | : *|| N ºy Q'ſ || ||a ! N |* gº | º | T | § N - N N INN Nº lºº N “Inflammable gas is introduced along a pipe into an open cylinder or vessel, whilst a flame placed on the outside of, but near to the cylinder, is constantly kept burning, and at times comes in contact with and ignites the gas therein; the cylinder is then closed air-tight, and the flame is prevented from com- municating with the gas in the cylinder. The gas continues to flow into the cylinder for a short space of time, then it is stop- ped off; during that time, it acts by its combustion upon the air within the cylinder, and at the same time a part of the rarefied air escapes through one or more valves, and thus a vacuum is effected. The vessel or cylinder is kept cool by water. Several mechanical means may be contrived to bring the above combination into use in effecting the vacuum with inflammable gas, and on the same principle it may be done in one, two, or more cylinders or vessels.”—Having a vacuum effected by the above combination and some mechanical contrivance, powers are produced by its application to machinery in several ways. First, water wheels may be turned ; secondly, water may be raised; and, thirdly, pistons may be worked. Description of the Engine as used for Turning a Water-wheel.— The two cylinders c and d are the vessels in which the vacuum is to be effected; from these descend the pipes gig and hj h leading into the lower cylinders ar, ar, from which the water rises along those pipes to fill the vacuum cylinders alternately. The water thus supplied is discharged through the pipes B into the tank or trough 2, whence it falls upon the overshot water-wheel, and by the rotatory motion thus produced gives power to such machinery as may be connected to it. The water runs from the wheel along a case surrounding the lower half, into a reservoir, v, from which the lower cylinders a r are alternately supplied. In order to produce the vacuum, the necessary quantity of gas is supplied to the cylinders by means of the pipe k k k, to be conveniently attached to a gasometer. The gas also passes along the small pipe l l, (communicating likewise with the gasometer,) and being lighted at both ends of that pipe, is con- stantly burning for the purpose of igniting the gas within the cylinders. The water in the reservoir v passing down one of the pipes w into one of the lower cylinders ar, causes the float y in that cylinder to rise, and pushing up the rod 0 raises the end b of the beam, which of course draws up with it the cap f and forces down the cap e of the other cylinder c. The gas being admitted along the pipe k, the flame from the pipe l is now freely com- municated to the gas in the cylinder through the orifice by the opening of the sliding valves, which is raised by the arm r lifted by the rod o by means of the beam. To produce the unremitting action of each cylinder, some subordinate machinery is put in operation by chains and rods attached to a glass or iron vessel p, partly filled with mercury, and, turning upon a pivot, each end receives its movements of elevation and depression from the rise and fall of the projecting arms q by the action of the beam above; the mercury being fur- nished for the purpose of regulating the supply of the gas into the cylinders, and the movement of the slide in the trough v. By the action thus communicated, the water from the reservoir flows down the pipe winto the vessel ar, and produces the eleva- tion of the float y and the rod n, and raises the cap e by the ascent of the beam at a. The motion thus caused in this part of the machinery, operating upon its duplicate parts on the other side, of course produces by its action a corresponding movement; and the slider in the trough v, moved by the action of the mercurial tube p, being removed from its position, allows the water to fall into the other pipe w, and as it ascends suffers the float y to descend, and rising into the main cylinder, thus lifts again the beam at b and its connexions, and forces down the cap e on the top of the other cylinder. After the vacuum is effected in the cylinders, the air must be admitted, to allow the water to be discharged and the caps to be raised; this is accomplished by means of a sliding valve in the air pipe m m, acted upon by chainst t, attached to the floats in the reservoir, V A. L. V A. R. 102} DICTIONARY OF MECHANICAL SCIENCE. and as motion is given to them, the valve is made to slide back- wards and forwards, so as to allow of the free admission of atmospheric air. Chains w w with suspended weights open the cocks in the pipe k k, and produce the alternate flow of the gas, and regulate and modify its supply. In the pipes g ig and hj h are clacks to prevent the return of the water when the air is admitted into the cylinders. When pistons are worked, the vacuum is effected (in the same manner as abovedescribed) under the piston, which is then pressed down by the weight of the atmosphere, and as an engine of that description is worked with two cylinders and pistons, the vacuum being produced in each cylinder alternately, the fall of one piston raises the other, and, being alternately pressed down, the piston rods give motion to the crank and fly- wheel. The air is admitted through large valves in the piston, and through orifices in the cylinders. An engine may be worked with one piston, the vacuum being produced in two cylinders, (as in the water engine,) from which a pipe communicates with a third cylinder in which the piston works, and into which the air is admitted alternately under and over the piston, while the vacuum extends to its opposite sides. By this contrivance a much greater rapidity of motion may be given to the piston, if required. The method being therefore explained, in which, by the pressure of the air, the vacuum produced (and continued) is applied to useful purposes, Mr. Brown claims to be the inventor of the combination above described for effecting a vacuum, “however much it may be varied by the mechanical means with which it may be used, and also the inventor of applying a vacuum produced by the combustion of inflammable gas, to raising water, and to the production of motign in machinery by th pressure of the atmosphere.” * The advantages to be derived from this engine, were detailed in the descriptive outline of the inventor, to be the following:— • 1st. “The quantity of gas consumed being very small, the expense of working the engine is moderate. In its application on land, the saving will be extremely great, the cost of the coal gas (deducting the value of the coke) being inconsiderable. The expense of working a marine engine will certainly be greater, as the gas used for that purpose must be extracted from oil, pitch, tar, or some other, substance equally portable, yet even in this case it will not equal the cost of the fuel required to propel a steam-boat; and, as a few butts of oil will be sufficient for a long voyage, vessels of the largest tonnage may be propelled to the most distant parts of the world. 2d. “The engine is light and portable in its construction, the average weight being less than one-fifth the weight of a steam- engine (and boiler) of the same power; it also occupies a much smaller space, and does not require the erection of so strong a building, nor of a lofty chimney. In vessels, the saving of ton- nage will be highly advantageous, both in the smaller compara- tive weight and size of the engine, and in the very reduced space required for fuel. - 3d. “This engine is entirely free from danger. No boiler being used, explosion cannot take place, and as the quantity of gas consumed is so small, and the only pressure that of the atmosphere, it is impossible that the cylinder can burst, or the accidents incidental to steam-boats occur.” The power of the engine being derived from the atmosphe- ric pressure of ten pounds and upwards to the square inch) may be increased with the dimensions of the cylinders to any extent, and aiways ascertained by the index of the mercurial gauge ; the power of the engine is best explained, by adverting to the fact of the mercury in the gauge being raised to the height of 24 inches and upwards. We saw it standing at 25 inches, though the inventor will not authorize any one to rate it higher than 22 inches, that being amply sufficient, as affording an available power superior to that of the condensing steam engine, there being no friction in an engine for raising water, and not Inore than one pound per square inch in a piston engine of any size. The number of strokes per minute which this engine made was twenty-nine, but a trifling alteration in the mechanism will increase the number to thirty-five or perhaps forty ; in fact, the vacuum is so instantaneously formed, that any number of strokes which could be wished may be made. When pistons are worked in a separate cylinder, two or three strokes of the piston may 108. be made with each stroke of the vacuum cylinder, i. e. each time the vacuum is effected. VAGABOND, a person who wanders about, having no cer- tain dwelling; such are sturdy beggars mentioned in divers statutes, on whom punishment may be inflicted. WAGRANTS, are those who threaten to run away and leave their wives and children to the parish. All persons returning to a parish whence they have been legally removed, without a certificate from the parish to which they belong. All who, not having wherewith to maintain themselves, refuse to work. All who beg alms from door to door, or in the streets and highways. Likewise those who, not using proper means to get employ- ment, or, possessing ability to work, refuse to do it; or spend money in ale-houses, or in any improper manner; and by not applying a proper proportion of their earnings towards the maintenance of their families, suffer them to become chargeable to the parish, * WALVE, in Hydraulics and Pneumatics, is a kind of lid or cover to a tube, vessel, or orifice, contrived to open one way, but which, the more forcibly it is pressed the other way, the closer it shuts the aperture, like the clapper of a bellows. VALve, in Anatomy, a thin membrane applied on several cavities and vessels of the body, to afford a passage to certain humours going one way, and prevent their reflux towards the place whence they came. - - VAN, or WAUN, in Mining, is the washing on a shovel a small quantity of tin stuff, or ore, that has been pulverized, so that the waste being washed away, the quality of a large heap may be estimated from the pruduce of pure ore remaining in the van. VAN, the foremost division of a naval armament, or that part which leads the way to battle, or advances first in the order of sailing. See the articles CENTRE, FLEET, REAR, &c. VANE, a piece of bunting sewed upon a wooden frame called the stock, which turns upon a spindle at the mast head : its use is to shew the direction of the wind. - - ... Distinguishing WANE, serves by its situation to denote what squadron a ship belongs to, and by its colour, or combination of colours, to point out the particular ship which bears it. Dog WANE, a small light vane formed of thin slips of cork, stuck round with feathers, and strung upon a piece of twine. It is usually fastened to the top of a half-pike, and placed on the weather side of the quarter deck, in order to shew the helms- man the direction of the wind, particularly in a dark night, or when the wind is weak. - VANes, in Mathematical or Philosophical Instruments, are sights made to slide and move upon cross-staves, fore-staves, quadrants, &c. - WANGS, a sort of traces to steady the mizzen peek, extending from the peek downwards to the aftmost part of the ship's quarters, where they are hooked and drawn tight, so as to be slackened when the wind is fair, and drawn in to windward when it becomes unfavourable to the ship’s course. WAPOUR, a thin vesicle of water, or other humid matter filled or inflated with air, which being rarefied, ascends to a cer- tain elevation in the atmosphere, and is there suspended till it returns in rain or snow. An assemblage of such vapours con- stitutes what is called a cloud. WAPOUR Bath. See BATH. VARIATION, is a term applied to the deviation of the mag- netic needle, or compass, from the true north point, towards either east or west, called also Declination. The variation of the needle is properly defined the angle which a magnetic needle suspended at liberty makes with the meridian line on an hori- zontal plane ; or an arch of the horizon, comprehended between the true and magnetical meridian. In the sea language it is usually called north-easting or north-westing. All magnetic bodies range themselves in some sort to the meridian; but it is rarely that they fall in precisely with it; in one place they de- cline from the north to the east, and from the south to the west; and in another place, on the contrary, from the north to the west, and from the south to the east, and that, too, differently at dif- ferent times. Various are the hypotheses framed to account for this extraordinary phenomenon ; we shall only mention some of the later and more probable; only premising, that Mr. Ro- bert Norman, the inventor of the dipping needles, disputes against 12 D T022 W. A. R. .W. A. R. Diction ARY of MechANICAL science. Cortes's notion, that a variation was caused by a point in the heavens, contending that it should be sought for in the earth, and proposes how to discover its place. The first is that of Gilbert, which is followed by Cabeus, &c. This notion is, that it is the earth or land that draws the needle out of its meridian direction; and hence they agree that the needle varied more or less. as it was more or less distant from any great continent; consequently, that if it were placed in the middle of an ocean equally distant from equal tracts of land on each side, west and westward, it would not decline either to the one or the other, but point justly north and soth. Thus they say, in the Azores, which are equally distant from Africa on the east and America on the west, no variation is found; but as from the Azores you sail towards Africa, the needle begins to decline from the north to the east, and that still more till you reach the shore. If you still proceed eastward, the declination gradually diminishes again, by reason of the land left behind on the west, which con- tinues to draw the needle. place where there are equal tracts of land on each side, and there again there is no variation. The observations of our ma- riners in their East India voyages seem to confirm this system. As they proceed towards the Cape of Good Hope, the variation is still eastward; at length arriving at the Cape de los Aguillas, q. d. of the needles, the meridian line then dividing Africa into two equal parts, there is no variation at all, but as they proceed farther, and leave the African coast on the west, the variation becomes westward. But the misfortune is, the law does not hold universally ; in effect, a great number of observations of the variations, in various parts, made and collected by Dr. Hal- ley, overturn the whole theory. Others, therefore, have recourse to the frame and compasses of the earth, considered as inter- woven with rocks and shelves, which being generally found to run towards the poles, the needle comes to have a general tend- ency that way, but which seldom going perfectly in the direc- tion of the meridian, the needle, of consequence, has commonly a variation. Others hold various parts of the earth to have various degrees of the magnetic virtue, as ‘some are more inter- | mixed than others with heterogeneous matters, which prevent the free action or effect thereof. Others ascribe all to mag- netic rocks and iron mines, which affording more of the mag- netic than other parts, draw the needle more. Lastly, others imagine earthquakes or high tides to have disturbed and dis- located several considerable parts of the earth, and so changed the magnetic axis of the globe, which originally was the same with the axis of the globe itself. ' - Dr. Hooke communicated to the Royal Society, in 1674, a theory of the variation, the substance of which is, that the mag- net has its peculiar pole, distant ten degrees from the pole of . the earth, about which it moves, so as to make a revolution in 370 years; whence the variation, he adds, has altered of late about 10 or 12 minutes every year, and will probably so conti- nue to do for some time, till it begins to become slower and slower, and will at length be stationary and retrograde, and in all probability may return. - Dr. Halley, in his day, gave another system, the result of a great number of observations, and even of a great number of voyages made at the public charge on this account. The light that excellent author imparted to this obscure portion of natu- ral history is very great, and the consequences thereof in navi- | dominion of all, as it is the most remote from the pole of the .gation, &c. are very considerable. . . From these observations the learned author infers, 1. Through- out all Europe the variation at this time is west, and is more in the eastern parts thereof than in the western, increasing that way. 2. That on the coast of America the variation is westerly, increasing all the way as you go northerly along the coast, so as to be about 20° at Newfoundland, nearly 30° in Hudson's Straits, and not less than 57° in Baffin's Bay; and that as you sail eastward from this coast, the variation constantly diminishes. Hence he argues that somewhere between Europe and the north part of America there must be an easterly variation, or at least no variation. 3. That on the coast of Brazil there is an east variation increasing as you go to the southward, so as to be 129 at Cape Frio, and 20° and half over against Rio Plata, and thence sailing south-westerly to the Straits of Magellan, it decreases to 17, and at the west entrance is about 14°. 4. That eastward of Brazil this easterly variation decreases, so as to be very The same holds till you arrive at a little at St. Helena and Ascénsion, and to be quite gone, and the compass point true about 11°, longitude west from the Cape of Good Hope. 5. That to the eastward of the aforesaid places, a westward variation begins, and governs in all the Indian Sea, rising to 18° under the equator, about the meridian of the northern part of Madagascar, and 27#9 in 39° south lati- tude near the same meridian; easterly from thence the west variation decreases so as to be not much above 8 at Cape Co- morin, and about 3° upon the coast of Java, and about the Molucca islands to be quite gone, as also a little to the west- ward of Van Diemen’s Land. 6. That to the eastward of the Moluccas and Van Diemen’s Land in south latitude, there arises another easterly variation, which seems not so great as the former, nor of so large extent; because, at the Isle of Rotterdam it is more sensibly felt than upon the east coast of New Guinea: and, at the rate it decreases, it may well be supposed that about 20° farther eastward, and 105 east longitude from London, in the latitude of 20° south, a westerly variation begins. 7. That the variation taken at Baldivia, and at the west entrance of the Straits of Magellan, shews that the east variation noted in the third observation is decreasing apace, and that it cannot extend many leagues from the South Sea into the coast of Peru and Chili, leaving room for a small westerly variation in that, tract of the unknown world that lies in the midway between Chili and New. Zealand, and between Hounds Island and Peru. 8. That in sailing north-west from St. Helena, by Ascension, as far as the equator, the variation continues very small east, as it were constantly the same ; so that in this part of the world, the course, wherein there is no variation, is evidently no meri- dian, but rather north-west. 9. That the entrance of Hudson’s Straits, and the mouth of Rio Plata, being nearly under the same meridian at the one place, the needle varies 294° west; at the other 20%" east. This, he says, demonstrates the impossi- bility of reconciling these variations by the theory of Bond, which is by two magnetical poles, and an axis inclined to the axis of the earth : whence it would follow, that under the same meridian the variation should in all places be the same. . From these circumstances the learned author takes occasion to assert, “that the whole globe of the earth is one great magnet, having four magnetical poles or points of attraction; near each pole of the equator two; and that in those parts of the world which lie nearly adjacent to any one of these magnetical poles, the needle is governed thereby, the nearest pole being always predomi- nant over the more remote.” The pole which at present is nearest to us, he conjectures to lie in or near the meridian of the Land's End of England, and not above 7° from the arctic pole ; by this pole the variations in all Europe and Tartary, and the North Sea, are principally governed, though still with some re- gard to the other northern pole, whose situation is in the meri- dian, passing about the middle of California, and about 15° from the north pole of the world, to which the middle has chiefly respect in all North America, and in the two oceans on either side thereof, from the Azores westward, to Japan, and farther. The two southern poles, he imagines, are rather farther distant from the south pole of the world, the one about 16° therefrom in a meridian, 20° to the westward of Magellan’s Straits, or 95° west from London ; this commands the needle in all South America, in the Pacific ocean, and the greatest part of the Ethiopic ocean. The other seems to have the greatest power and the largest world, being little less than 20° distant therefrom in the meri- dian which passes through New Holland and the island of Ce- lebes, about 120° east from London; this pole is predominant in the south part of Africa, in Arabia and the Red sea, in Persia, India, and its islands, and all over the -Indian Sea, from the Cape of Good Hope eastwards to the middle of the Great South Sea, that divides Asia from America. Such seems to be the present disposition of the magnetical virtue throughout the whole globe of the earth. It remains to shew how this hypothe- sis accounts for all the variations that have been observed of late, and how those variations answer to the several remarks which Dr. Halley made. . It is plain, as our European north pole is in the meridian of the Land’s End of England, all places more easterly than that will have it on the west side of the meridian ; and consequently the needle, respecting it with its northern point, will have a west- V. A. T. V. A R 1023 DICTIONARY OF MECHANICAL SCIENCE. erly variation, which will still be greater as you go to the east- ward, till you come to some meridian of Russia, where it will be the greatest, and from thence will decrease again. Accord- ingly, in fact we find that at Brest the variation was but 14°, at London 43° (in 1683) and at Dantzic 7° west. - Again, to the westward of the meridian of Land's End, the needle ought to have an easterly variation, were it not that by approaching the American north pole (which lies on the west side of the meridian, and seems to be of greater force than this other) the needle is drawn thereby westward, so as to counter- balance the direction given by the European pole, and to make a small west variation in the meridian of the Land's End itself. Yet, about the Isle of Tercera, it is supposed our nearest pole may so far prevail as to give the needle a little turn to the east, though but for a very little space, the counterbalance of those two poles admitting no considerable variation in all the east- erm ports of the Atlantic ocean, nor upon the west coasts of England and Ireland, France, Spain, and Barbary. But to the westward of the Azores, the power of the American pole over- coming that of the European, the needle has chiefly respect thereto, and turns still more and more towards it as we approach it. Whence it comes to pass, that on the coast of Virginia, New England, Newfoundland, and in Hudson's Straits, the va- riation is westward, that is, it decreases as you go from thence towards Europe, so that it is less in Virginia and New Eng- land than in Newfoundland and Hudson’s Straits. 2. This westerly variation again decreases as you pass over North America, and about the meridian of the middle of Califor- nia, the needle again points due north ; and from thence west- ward to Yedzo and Japan, it is supposed the variation is easterly, and half sea over not less than 15°; and that this east variation extends over Japan, Yedzo, Tartary, and part of China, till it meets with the westerly, which is governed by the European north pole, and which is the greatest some- where in Russia. - - 3. Towards the south pole the effect is much the same, only that here the south point of the needle is attracted. Whence it will follow, that the variation on the coast of Brazil, at the river of Plata, and so on to the Straits of Magellan, should be easterly, if we suppose a magnetical pole situate about 200 more westerly than the Straits of Magellan. And this easterly .variation extends eastward over the greatest part of the Ethio- pie sea, till it be counterpoised by the virtue of the other south- ern pole, as it is about midway between the Cape of Good Hope and the Isles of Tristan d'Alcunha. 4. From thence eastward, the Asiatic south pole becoming pre- valent, and the south point of the needle being attracted thereby, there arises a west variation very great in quantity and ex- tent, because of the great distance of this magnetical pole from the pole of the world. Hence it is, that in all the Indian seas, as far as New Holland, and farther, there is constantly a west variation, and that under the equator itself it rises to no Jess than 11° where it is most. And that about the meridian of the island of Celebes, being likewise that of this pole, this westerly variation ceases, and an easterly one begins, which reaches to the middle of the South Sea, between New Zealand and Chili, leaving room for a small west variation, governed by the American south pole. , 5. From the whole it appears that the direction of the needle in the temperate and frigid zones depends chiefly upon the coun- terpoise of the forces of two magnetical poles of the same nature; as also why, under the same meridian, the variation should be in one place 294° west, and in another 20%9 east. 6. In the torrid zone, and particularly under the equinoctial, respect must be had to all the four poles, and their position must be well considered, otherwise it will not be easy to determine what the variation shall be, the nearest pole being always strong- est; yet not so as not to be counterbalanced sometimes by the united forces of two more remote. Thus in sailing from St. JHelena by the isle of Ascension to the equator, on the north- west course, the variation is very little easterly, and in that whole tract is unalterable; because the South American pole, which is considerably the nearest in the aforesaid places, re- quiring a great easterly variation, is counterpoised by the con- trary attraction of the North American and the Asiatic south poles; each whereof singly is, in these parts, weaker than the American south pole, and upon the north-west course the dis- tance from this latter is very little varied; and as you recede from the Asiatic south pole, the balance is still preserved by an access towards the North American pole. In this case, no notice is taken of the European north pole, its meridian being a little removed from those of these places, and of itself requiring the same variations. And after the same manner may the variations in other places, under and near the equator, be ac- counted for. VARIATION of the Variation, is the change for the declination of the needle, observed at different times in the same place. This variation was first discovered by Mr. Henry Gellibrand, by comparing the observations made at different times near the same place by Mr. Burrough, Mr. Gunter, and himself, and the discovery was soon known abroad; for Kircher, in his treatise intitled “Magnes,” says, that our countryman, Mr. John Creaves, had informed him of it; and then gives a letter of the famous Mersennus, containing a very distinct account of it. Indeed, in the History of the Royal Academy of Sciences at Paris, it is said by M. de Fontinetti, that the learned Gassendi himself acknowledged that he had before received information of Gellibrand’s discoveries. This change is gradual and univer- sal, and not accountable for. According to Dr. Halley, the variation of the variation of the compass is supposed to be owing to the difference of velocity of the motions of the internal and external parts of the globe. Such are the irregularities that experience has shewn us in the variation of the magnetic needle, which appear so considerable, that we cannot think it wholly under the direction of one general and uniform law ; but rather conclude, with the learned and judicious Dr. G. Knight, that it is influenced by various and different magnetic attrac- tions, in all probability occasioned by heterogeneous composi- tions in the great magnet, the earth. VARNISHING. Varnish is a clear limpid fluid, which hard- ens without losing its transparency. It is used by painters, gilders, &c. to give a lustre to their works, and to preserve and defend them from the air and moisture. A coat of warnish ought to possess the following properties: 1. It must exclude the action of the air; because wood and metals are varnished to defend them from decay and rust. 2. It must resist water; else the effect of the varnish could not be permanent. 3. It ought not to alter the colours it is intended to preserve. It is necessary, therefore, that every varnish should be easily spread over the surface, without leaving pores or cavities, that it should not crack or scale, and that it should resist water. - Resins are the only bodies that possess these properties; they must therefore form the basis of every varnish. For this purpose they must be dissolved as minutely divided as possi- ble, and combined so that the imperfections of those that might be disposed to scale may be corrected by others. Resins may be dissolved by three agents: 1. by fixed or fat oil ; 2. by vo- Hatile or essential oil ; 3. by spirit of wine. Accordingly we have three kinds of varnish; fat or oily varnish, essential var- nish, and spirit varnish. And these agents are of such a nature as either to dry up and become hard, or else to evaporate and fly off, leaving the resin fixed behind. Warnishes should be carefully kept from dust, and in very clean vessels: they should be laid thin and even with a large flat brush, the strokes being drawn all one way. A warm room does best for varnishing in, cold chills the varnish and prevents it from lying even. .. Warnishes are polished with pumice-stone and tripoli. The pumice-stone reduced to a fine powder is put upon a piece of serge moistened with water; and with this the varnished substance is rubbed equally and lightly. The tripoli, also reduced to a fine powder, is put upon a clean woollen cloth moistened with olive oil, with which the polishing is performed. The varnish is then wiped with soft linen, and when dry, cleaned with starch, or Spanish white, and rubbed with the palm of the hand, or a linen cloth. Fat Oil Warnish.-Fixed or fat oil does not evaporate, nor become dry of itself. And therefore to make it dry it is boiled with metallic oxydes. Litharge is generally used for this pur- pose. Oil so prepared is called drying-oil. But to accelerate the drying of oil-varnish, we add oil of turpentine. 1024 W A U. V. A. R. DICTIONARY OF MECHANICAL SCIENCE, Gum-copal and amber are the substances chiefly employed in oil warnishes; the copal is white, and used for varnishing light, the amber for dark colours. Before mixing them with the oil, it is best to dissolve them; because they are then in less danger of being scorched, the varnish is also more beautiful. They should be melted in an iron pot; they are in a proper state for receiving the oil when they offer no resistance to the iron spatula, and run off from it drop by drop. To make oil varnish, pour, by little and little, six or eight ounces of drying oil among sixteen ounces of melted copal or amber, constantly stirring the ingredients with the spatula. When the oil is well mixed with the copal or amber, take it off the fire; and when nearly cool, put in sixteen ounces of the essence of Venice turpentine. The varnish should be passed through a linen cloth. Oil warnishes become thick by keeping; when they are to be used, it is only necessary to pour in a little Venice turpentine, and put them a short time on the fire. Less turpentine is necessary in summer than winter; too much oil hinders the varnish from drying ; when too little is used, it cracks and does not spread properly. To make the best White Hard Warnish.-Rectified spirits of wine, 2 galls. ; gum ancine, 4 oz. : gum mastich, 1 lb. ; gum san- 'darach, 5 lbs. Put these into a clean can or bottle to dissolve, in a warm place, frequently shaking it; when the gum is dis- solved, strain it through a lawn sieve, and it is then fit to use. Black Warnish for Coaches and Iron Work.-This varnish is composed of asphaltum, resin, and amber, melted separately, and afterwards mixed, the oil is then added, and afterwards the turpentine, as directed above. The proportions are, twelve ounces of amber, two of resin, two of asphaltum, six of oil, and twelve of turpentine. - A Warnish for rendering Silk Impenetrable to Water and Air.— To render linseed-oil drying, boil it with two ounces of sugar of lead, and three ounces of litharge, for every pint of oil, till the oil has dissolved them ; then put a pound of bird-lime, and half a pint of the drying, oil, into an iron or copper pot holding about a gallon, and let it boil gently over a slow charcoal fire, till the birdlime ceases to crackle ; then pour upon it two pints and a half of drying oil, and boil it for about an hour longer, stirring it often with an iron or wooden spatula. As in boiling the varnish swells much, the pot should be removed from the fire, and replaced when the varnish subsides. While it is boil- ing it should be occasionally examined, to determine whether it has boiled enough. For this purpose take some of it upon the blade of a large knife, and after rubbing the blade of an- other knife upon it, separate the knives; and when on their se- paration the varnish forms threads between the two knives, it has boiled enough, and should be removed from the fire. When it is almost cold, add about an equal quantity of spirits of tur- pentine ; mix both well together, and let the mass rest till the next day; then having warmed it a little, strain and bottle it. If it is too thick, add spirits of turpentine. This varnish should be laid upon the stuff when perfectly dry, in a lukewarm state ; a thin coat of it upon one side, and about twelve hours after two other coats should be laid on, one on each side; and in twenty-four hours the silk may be used. Blanchard's Air Balloon Warnish.-Dissolve elastic gum (Indian-rubber.) cut small, in five times its weight of spirits of turpentine, by keeping them some days together; then boil one ounce of this solution in eight ounces of drying linseed-oil for a few minutes, and strain it: use it warm. Essential Oil Warnish.—The essential varnishes consist of a solution of resin in oil of turpentine. This varnish being applied, the turpentine evaporates, leaving the resin behind. They are commonly used for pictures. - . To dissolve Gum Copal in Oil of Turpentine.—The quantity to be dissolved should be put into a glass vessel capable of con- taining at least four times that quantity, and it should be high in proportion to its breadth. Reduce two ounces of copal to small pieces, put them into a proper vessel. Mix a pint of oil of turpentine with one-eighth its quantity of spirit of sal ammoniac; shake them well together; put them to the copal, cork the glass, and tie it over with a string of wire, making a small hole through the cork. Set the glass in a sand heat so regulated as to make the contents boil as quickly as possible. but so gently, that the air-bubbles may be counted as they rise from the bottom. The same heat must be kept up till the solu- tion is complete. It requires accurate attention to succeed in this operation. After the spirits are mixed they should be put to the copal, and the necessary degree of heat given as soon as possible. It should likewise be kept up with the utmost regu- larity. If the heat abates, or the spirits boil quicker than is necessary, the solution will immediately stop, and with the same materials will afterwards be in vain to proceed: but if properly managed, the sal ammoniac spirit will gradually de- scend from the mixture, and attack the copal, which will swell and dissolve, except a very small quantity that will remain undissolved. The vessel should not be opened till some time after it has cooled, as it has happened that on uncorking the vessel when it was not warm enough to affect the hand, that the contents have been blown against the ceiling. The spirit of turpentine should be of the best quality, had from Apothecaries’ Hall. This varnish, though a rich deep colour in the bottle, gives no colour to the pictures it is laid on. If left in the damp it remains tacky a long time; but in a warm room, or the sun, it dries as other turpentine varnishes. Spirit Warnishes.—When resins are dissolved in alcohol,(spirits of wine,) the varnish dries speedily, but cracks. This fault is corrected by adding a small quantity of oil of turpentine, which renders it brighter and less brittle when dry. - To dissolve Gum Copa l in Spirits of Wine.—Dissolve half an ounce of camphor in a pint of alcohol, put it into a circulating glass, add four ounces of copal in small pieces; set it in a sand heat, so regulated that the air-bubbles may be counted as they rise from the bottom ; and continue the same heat till the solution is completed. Camphor acts more powerfully upon copal than any other substance. If copal finely powdered be rubbed with a small quantity of dry camphor in the mortar, the whole becomes in a few minutes a tough coherent mass. The most economical method is to set the vessel which contains the solu- tion by for a few days; and when perfectly settled, pour off the clear varnish, and leave the residuum for a future operation. This is a very bright solution of copal, and an excellent varnish for pictures, besides being an improvement in fine japan works, as the 'stoves used in drying those articles may drive off the camphor entirely, and leave the copal pure and colourless upon the work. Copal dissolves in spirits of turpentine, by the addi- tion of camphor, with the same facility, but not in the same quantity, as in alkohol. A Varnish for Wainscot, Came Chairs, &c.—Dissolve in a quart of spirits of wine, eight ounces of gum-sandarach, two ounces of seed-lac, and four ounces of resin ; then add six ounces of Venice-turpentine. If the varnish is to produce a red colour, more of the lac and less of the sandarach should be used, and a little dragon's blood should be added. This varnish is very strong. w : A Warnish for Toilet Boarés, Cases, Fans, &c.—Dissolve two ounces of gum-mastich, and eight ounces of gum sandarach, in a quart of alcohol ; then add four ounces of Venice turpentine. A Varnish for Violins, and other Musical Instruments.-Put four ounces of gum sandarach, two ounces of lac, one ounce of gum-elemi, into a quart of alcohol, and hang them over a slow fire till they are dissolved ; then add two ounces of turpentine. Varnish for employing Vermilion for Painting Equipages.—In a quart of alcohol dissolve six ounces of gum sandarach, three ounces of gum lac, and four ounces of resin; add six ounces of the cheapest kind of turpentine afterwards: mix it with a proper quantity of vermilion when used. Seed Lac Warnish.-Put one quart of spirits of wine in a wide- mouthed bottle, add eight ounces of seed-lac, clear and free from dirt ; let it stand two days or longer in a warm place, shaking it often. Strain it through a flannel into another bottle, and it will be fit for use. * Shell-Lac Warnish.--Take one quart of spirits of wine, eight ounces of thin transparent shell lac, which if melted in the flame of a candle, will draw out in fine long hair; mix and shake these together, and let them stand in a warm place for two days, and it will be ready for use, This varnish is softer than that made from seed-lac, and not so useful, but may be mixed with it for varnishing wood, &c. White Warnish for Clock Faces, &c.—Take of highly rectified spirits of wine one pint, which divide into four parts; then mix one * v A U V A U 1025 DICTIONARY OF MECHANICAL SCIENCE. part with half an ounce of gum-mastich in a phial, one part of spirits, and half an ounce of gum-sandarach in another phial, one part of spirits, and half an ounce of the whitest parts of gum- benjamin. Then mix and temper them to your mind, and it may not be amiss to add a little bit of white resin, ochre, Venice turpentine, in the mastich bottle, to give a gloss. If your varnish be strong and thick, add spirits of wine only ; if hard, some dis- solved mastich ; if soft, some sandarach of benjamin. When you have brought it to a proper temper, warm the silvered plate Before the fire (if a clock face, taking care not to melt the wax,) and with a flat camel's hair pencil stroke it all over until no white streaks appear, and this will preserve silvering many years. . VASE. See URN. - . VAULT, in Architecture, an ached roof, so contrived that the stones which form it sustain each other. Vaults are, on many occasio, s, to be preferred to soffits or ceilings, as they give a greater height and elevation, and are besides more firm and durable. - - VAULTING, in the article GYMNAstics, page 430, we refer- red to the word Vaulting for this branch of those physical ex- ercises.—By means of a very simple instrument a great number of our most useful exercises in vaulting may be executed. The figures 6 and 7 of the plate Gymnastic Exercises can be em- ployed to perform all the exploits of the pole. The vaulting beam i k, fixed between the two standards c d, renders it fit for performing on it all the elementary exercises of vaulting. A board with the edges rounded, placed in the same direction, between the standards, may serve to accustom young people to walk on narrow objects, fixed at several elevations. The same board, as in ef, fig. 7, fixed like the pole, can be employed with advantage to accustom them to raise the body as high as possi- ble, supported only by the last phalanges of the fingers. A rope with a small sack filled with sand at éach end, two little iron spikes to support and make it easily moveable upwards and downwards, presents the most useful and least dangerous instru- ment to exercise boys in every kind of jumping.—Those who have but a small room, in order to exercise the arms, may fix in one of the corners, at six or eight feet from the ground, and from one wall to the other, a strong pole, eight feet long and three inches thick, on which the following exercises can be per- formed, which are the most useful in increasing prodigiously the strength of the upper limbs. - - - Hanging by both Arms, Figure 7, No. 1 and 4.—Here the two arms ought to support for several minutes the whole weight of the body, by which they will be stretched while all the other parts of the body hang loose. This cannot be done by children of a weak constitution, for it is necessary that they should raise their knees, and for safety, some one should remain near them to prevent their falling. In descending, let both hands go at once, and light on both points of the feet, the knees bent as a bird alights, and the upper part of the body inclined forwards. Hanging alternately on one Hand and Foot, No. 3. • * Hanging on both Hands, the Nails turned inside, No. 1 and 4. Hanging on both Arms outside, like No. 5,-In this position communicate to the body a swinging movement backwards and forwards; and after balancing a moment jump backwards, let go both hands at once, and come down on the points of the feet. Sliding Sideways.—This consists in bringing the body from one end of the pole to the other, by moving upon it one hand after another in an oblique direction. Children of a weak con- stitution ought, during this action, to be a little sustained in the loins; and it is necessary to oblige them, during the exercise, to raise their knees as high as possible, and to move them in concert with the arms. t - Hand over Hand.—Fixed on the pole, as is represented in No. 4, move forwards and backwards, passing one hand over the other, carefully observing in the beginning to fix the hands not too far from one another. * Advancing by Jumps, Or moving both hands at once from one place to another; at first forwards from one end of the pole to the other, and after that the same exercise in a contrary direction. * * * - - 2 - Hanging on the Elbows backwards, and Balancing.—In this movement it is necessary in jumping down, to let go both arms at once, in the very moment the feet are moving backwards. 108. Changing both Hands at once,—Is to take several times alter- nately the position as figs. I and 4, without coming on the ground. Right about Face,—Is one of the most difficult of these ex- ercises; it ought therefore to be made very gently. Fixed as in No. 4, after having raised the body as high as possible, let go both hands at once, bring them on the pole in an opposite direction, as you were before. By this movement the body has made right about face. To turn over, No. 6.-The hands fixed as before; after a strong movement of impulse, bring your legs upwards and lie upon the pole with the girdle, or if you can well support your- self without loosening your hands, turn round the pole and come on your feet. * . - - - This is the genuine Salto mortale, fixed by the hands or feet over-head. The same exercise can be done having the hands fixed as in number 5 and 6. - To Slide down.—Sitting in the middle of the pole, both hands fixed on one side of the body, to the right for example. The right hand near the right hip, the nail turned to the face, the hands strongly fixed. From this position slide gently forward, and you will hang on both arms; after having turned over, come up again, sit upon the poles as before, and repeat the exercise several times on both sides without coming on the ground. Leaping.—In general, of all the leaps, the most sure, useful, and agreeable, is the vaulting in a straight direction, and is that which we can employ on a great many occasions. A man who has acquired the facility to perform it well, may easily jump over objects of his own height, and even more, without any danger whatever. - . The first exercises which we ought to make in order to sup- ple all the joints, are in general, the most useful and profitable for every kind of jump. * In raising the knees and supporting the body in equilibrium upon the hands, bring the legs several times up and down with- out touching the beam with any other part of the body. After hav- ing practised this exercise a little time, it will be very easy for any body to stand on the beam, since, to rise up from the first po. sition, there is nothing else to be done than to bend the body a little forwards, bring the heel of the right foot before the anche of the left, and rise up gently. To come down, the knees bent gradually, the hands come on the beam, and as soon as the weight of the body lies upon them, the feet leave their place, and take their first position. - - In Walking forwards,--From the first position, bring one hand forwards by sliding it close to the other, till the last arti- culation of the thumb of the moving hand comes in the direction of the nail of the other, and then continue on the same way till you can perform it with ease, always observing an equal distance in your steps. In Walking backwards,—The same exercise, moving back- wards, though much more difficult than the preceding, may be executed very soon by those who have well observed the rules of the former. Here, while the hands are moving backward, the upper part of the body is kept forward. - . Jumping between.—To perform this exercise easily, place the beam the height of the middle of the thigh ; put both hands upon it, and by giving a little impulse upwards, brings both feet at once, close between the hands, without moving them from their place, and continue the same exercise until it can be done easily. Having acquired some dexterity in this, try, by jump- ing in the same manner, to pass one leg through the hands, and return without touching the beam with it. In passing the leg through, the body is kept backward, and in bringing it back, it is bent forward. Do the same with both legs together, observ- ing the same rules. . * Jumping through.-Here it is necessary to have some one to stand by to assist; and in the beginning this exercise ought to be made with very great precision. The preceding exercises hav- ing been well made, it will be very easy to jump through the hands, because there is nothing else to be observed than to push the body forwards and let both hands go at once after the legs are passed through the hands in a straight direction. Jumping over.—This manner of jumping is very agreeabie and sure, because in the action we have always the power to direct the body with the greatest ease in whatever direction we please. Placed before the beam, which is at first as high as 12 E - T026 v E E V E N DICTIONARY OF MECHANICAL SCIENCE. the hips, lay both hands upon it, then bending down raise the body at once with all your strength over the beam. In jump- ing to the right, the left foot passes between both hands, the right hand lets go, and the left guides the body in its fall. In jumping to the left, the right foot passes between both hands. In whatever direction this jump be made, you ought not only to be master of your equilibrium, but must also be able to point out, before jumping, the place where you intend to fall, observ- ing at the same time to come on the ground on both feet, the knees projected forward, the hands ready to neutralize the fall if necessary. Parallel Bars.-The instruments employed to perform the ex- ercises here described, are two pieces of wood from six to eight feet in length, and four inches square, the edges rounded. For grown men they are fixed at two feet distance from one an- other, and for children, at eighteen inches, supported by two round standards firmly fixed in the ground, and from three to four feet high, according to the stature of the boys. It is necessary that during the exercises the instructor should always remain near the boy who is exercising, on pur- pose to assist him if he should make a false movement. Balancing, No. 1.-Being placed in the middle of the bars, and between both, put your hands right and left on each bar on the same line. After a little jump upwards, preserve your equi- librium on both wrists, the legs close, and in that position which we call the first: then communicate to your body a gentle move- ment of balancing from behind, forwards, and continue so se- veral times. In the beginning, it is necessary to observe, not to bring the feet too high to make this exercise with precision, and without making any movement with the arms; the body moving as it were upon a pivot. To bring both legs over.—From the first position, after a little movement of balancing, bring both legs close and at once, over one of the bars forwards without touching it, or moving your hands from their place. The same ought to be made backwards right and left. - Crossing.—After having made several times the preceding exercises, and got some readiness in them, you can try this: having both legs on the right (where the right hand lies) bring them in at once upon the left backwards, after that between, then over the left forwards, from thence over the right back- wards, and continue on in the same manner from right back- wards to the left forwards, between, over the right forwards, and over the left backwards. Doubling.—Having both legs over the left bar, forwards, bring them close, and without falling between, or touching the bars, place them over the right forwards, then over the left, and continue so for some time. The same exercise, behind, is much more difficult, but by practice you may acquire readiness in this as well as in the former. Observe to bring the body forwards at the same time that you bring your legs over both bars. - To Jump out.—After having communicated to the body a movement of balance, the moment in which the legs are raised over the bars, jump backwards over the right, without touching it with the feet or waist; then perform the same jump forwards. By the vaulting jump you may easily come between the bars, and also bring your body over both, without touching them otherwise than with your hands. To rise up, fived by the legs.-Sitting upon one of the bars, place the upper part of your feet under the lower part of the other bar, and slide backwards upon your thighs till you come to hang in the joints of your knees. In this position the points of your feet, and the upper part of your calves, are the only part of the body which touch the bars. Also fixed, bring the upper part of your body gently down and backwards, laying your hands crossed upon the chest, and holding the head upright, then raise up your trunk several times. At the beginning make this exercise no more than five or six times without rest. When once accustomed to it, you may perform it forty or fifty times without any ill consequence attending it. . . - Moving upon the Hands forwards and backwards.--To perform this exercise either forwards or backwards, it is necessary to ºake but little movement in sliding your hands upon the bar, ‘holding the body upright. No. 1. - Advancing by Leaps.--From the first position, after having them always in the same line. communicated to the body an impulsion forwards, lift both hands at once, and bring them forwards upon the bars, keeping To execute this exercise back. wards, it is necessary to keep the upper part of the body as much forwards as possible. - - - To rise, and sink down, No. 2.-In equilibrium in the middle of the bars, place the legs backwards, the heels close to the upper part of the thigh. From this position come gently down till the elbows rest upon the bars; then rise up gently without any impulse, or touching the ground with your feet. This ought to be repeated several times without resting. . As soon as you can perform this easily, in rising up try to bring the knees as high as possible in the direction of the face. - To touch the ground with the knees.—In this exercise the legs are folded backwards, and the same movements are made as in the former, by going gently down between the bars, till the knees touch the ground, moving up and down several times. VECTOR, in Astronomy, a line supposed to be drawn from any planet moving round a centre, or the focus of an ellipsis, to that centre or focus. To VEER AND HAUL, to pull a rope tight by drawing it in and slackening it alternately till the body to which it is applied acquires an additional motion like the increased vibrations of a pendulum, so that the rope is strained to a greater tension with more facility and despatch; this method is particularly used in hauling the bowlines. The wind is said to veer and haul when it alters its direction, and becomes more or less fair. Thus it is said to veer aft, and haul forward. WEERING is the operation by which a ship, in changing her course from one board to the other, turns her stern to wind- ward. See the article WA Re. VEIN, among Miners, is that space which is bounded with woughs, and contains ore, spar, canck, clay, chirl, croil, brow- heu, pitcher-chirt, cur, which the philosophers call the mother of metals, and sometimes soil of all colours. When it bears ore, it is called a quick vein; when no ore, a dead vein. WELVET, a rich kind of stuff, all silk, covered on the outside with a close, short, fine, soft shag, the other side being a very strong close tissue. - VENEERING, VANEERING, or Fineering, a kind of marque- try or inlaying, whereby several thin slices or leaves of fine woods, of different kinds, are applied and fastened on a ground of some common wood. There are two kinds of inlaying, the one which is the most common and more ordinary, goes no farther than the making of compartments of different woods; the other requires much more art, in representing flowers, birds, and similar figures. The first kind is properly called veneering, the latter is more properly called marquetry. The wood used in veneering is first sawed out into slices or leaves about a line in thickness; i. e. the twelfth part of an inch. In order to saw them, the blocks or planks are placed upright, in a kind of sawing press. These slices are afterwards cut into narrow slips, and fashioned divers ways, according to the design proposed; then the joints having been exactly and nicely adjusted, and the pieces brought down to their proper thickness with several planes for the purpose, they are glued down on a ground or block with good strong English glue. The pieces being thus jointed and glued, the work, if small, is put in a press; if large, it is laid on a bench, covered with a board, and pressed down with poles or pieces of wood, one end of which reaches to the ceiling of the room, and the other bears on the board. When the glue is thoroughly dry, it is taken out of the press and finished, first with little planes, then with scrapers, some of which resemble rasps, which take off the dents, &c. left by the planes. After it has been sufficiently scraped, they polish it with the skin of a dog-fish, wax, and a brush, or polisher of shave-grass; which is the last operation. VENOM. See POISON. VENTILATION, comprises the various modes by which impure air is removed or renovated by introducing a current of pure atmospheric air. * VENTILATOR, a machine by which the noxious air of any close place, as a hospital, gaol, ship, chamber, &c. may be changed for fresh air. - i VENTRILOQUISM, an art by which certain persons can so modify their voice as to make it appear to the audience to v E S "W I N DICTIONARY OF MECHANICAL SCIENCE. 1027 ..proceed from any distance, and in any direction. It appears that wentriloquism is the art of mimicry, an imitation ap- plied to sounds of every description, and attended with cir- cumstances which produce an entertaining deception, and lead the hearers to imagine that the voice proceeds from different situations. When distant, and consequently lower voices are to be imitated, the articulation may be given with sufficient distinctness, without moving the lips, or altering the counte- nance. It was by a supposed supernatural voice of this kind, from a ventriloquist, that the famous musical small-coal man, Thomas Britton, received a warning of his death, which so greatly affected him that he did not survive the affright. VENUE, the neighbourhood from whence juries are to be summoned for trial of causes. In local actions, as of trespass and ejectment, the venue is to be from the neighbourhood of the place where the lands in question lie; and in all real actions the venue must be laid in the county where the property is for which the action is brought. - VENUS, in Astronomy, one of the inferior planets, revolving round the sun in an orbit between that of Mercury and the Earth. VEPRECULAE, diminutive from vepres, “a briar or bram- ble,” the name of the thirty-first order in Linnaeus’s Fragments of a Natural Method. VERB, in Grammar, a word serving to express what we affirm of any subject, or attribute to it. - VERDICT, the answer of a jury made upon any cause, civil or criminal, committed by the court to their examination; and this is two-fold, general or special. A general verdict is that which is given or brought into the court in like general terms to the general issue ; as, guilty or not guilty generally. A spe- cial verdict is, when they say at large that such a thing they find to be done by the defendant or tenant so declaring the course of the fact, as in their opinion it is proved ; and as to the law upon the fact, they pray the judgment, of the court; and this special verdict, if it contain any ample declaration of the cause from the beginning to the end, is also called a verdict at large. A special verdict is usually found where there is any difficulty or doubt respecting the laws, when the jury state the facts as proved, and pray the advice of the court thereon. A less expensive and more speedy mode, however, is, to find a verdict generally for the plaintiff, subject, nevertheless, to the opinion of the judge, or the court above, or a special case drawn up and settled ...’ counsel on both sides. VERDIGRIS, is an acetate of copper, useful in the arts as a pigment. VERGERS, certain officers of the courts of King's Bench and Common Pleas, whose business it is to carry white wands before the judges. There are also vergers of cathedrals, who carry a rod, tipped with silver, before the bishop, dean, &c. VERJUICE, a liquor obtained from grapes or apples unfit for wine or cider; or from sweet ones whilst yet acid and unripe. VERMES, in Natural History, the last class of the animal kingdom, according to.the Linnaean system. The animals in this class are not merely those commonly known by the name of worms, but likewise those which have the general character of being “slow in motion, of a soft substance, extremely tena- cious of life, capable of reproducing such parts of their body as may have been taken away or destroyed, and inhabiting moist places.” There are five orders in this class, viz. the infusoria, intestina, mollusca, testacea, zoophyta. VERMICELLI, a composition of flour, cheese, yolks of eggs, sugar, and saffron, reduced to a paste, and formed into long slender pieces like worms, by forcing it with a piston through a number of little holes. VERMIN, a collective term which includes the various sorts of small animals that are injurious to the corn, fruit, and other produce of the farmer. VERNIER, a scale adapted for the gradation of mathematical in StrumentS. VERSE. See POETRY. - - - VERSED SINE of AN ARCH, a segment of the diameter of a circle, lying between the foot of a right sine and the lower extremity of the arch. - VERTICAL CIRCLE, in Astronomy, a great circle of the sphere passing through the zenith and nadir, and cutting the horizon at right angles: it is otherwise called azimuth. º VERTICAL Plane, in Perspective, is a plane perpendicular to the geometrical plane, passing through the eye, and cutting the perspective plane at right angles. - . . . . VESPERTILIO, the Bat, in Natural History, a genus of mammalia, of the order primates. Generic character: teeth erect, sharp-pointed, approximated ; fore-feet palmated, with a membrane surrounding the body, and by which the animal is enabled to fly. Bats fly only by might, in quest of their food, consisting of gnats and moths, and when deprived of their eyes appear to feel no want of them, having a supplementary power of perception, by which they avoid objects in the way with nearly as much precision as in their perfect state. In cold climates they pass the winter in torpor, assembling in holes and in caverns, in which they are occasionally seen adhering in great numbers to the walls, and sometimes suspended by their hind legs. The bones of the extremities of the fore-legs of bats are continued into long and thin processes, connected by a fine and almost transparent skin, which they are enabled to unfold optionally for flight, or to withdraw into a very small compass, when they wish to repose. The general division is into those which have tails, and those which have none. There are twenty- five species. - . . . VESSEL, a general name given to all the different sorts of ships which are navigated in the ocean, or in canals and rivers. It is, however, more particularly applied to those of the smaller kind, furnished with one or two masts. . . . . . WESTIBULE, in Architecture, a kind of entrance into a large building ; being a place before the hall, or at the bottom of the staircase. - WESTRY, a place adjoining to a churgh, where the vest- ments of the minister are kept; also a meeting at such place where the minister, churchwarden, and principal men of most parishes, at this day make a parish vestry. VESUVIAN, a mineral found in lava, especially at Vesuvius, and formerly confounded with hyacinth. Its colour is brown or greenish. It is found in masses, but usually crystalized in rectangular eight-sided prisms. The primitive form of its crystal is the cube. The specific gravity is from 3:39 to 34. VIBRATION, in Mechanics, a regular reciprocal motion of a body, as a pendulum, &c. which, being freely suspended, swings, or oscillates, first this way, then that. * * - VICAR, one who supplies the place of another. The priest of every parish is ...} rector, unless the praedial tithes are appropriated, and then he is styled vicar, and when rectories are appropriated, vicars are to supply the rector’s place. Prior to the Reformation, when the patronage of a parish was in the hands of a religious house, the monks usually detained the larger portion of the tithes, and appropriated a certain portion for the support of the vicar whom they appointed to perform the duties. Such tithes are now enjoyed by the vicar, and the other tithes by the lay impropriator, or other parties wh inherit the property of the religious houses. & - VICE, in Smithery, and other arts employed in metals, is a machine or instrument, serving to hold fast any thing they are at work upon, whether it is to be filed, bent, riveted, &c. - Vice, Hand, is a small kind of vice serving to hold the lesser works, that require often turning about. Vice is also a machine used by the glaziers to turn or draw lead into flat rods, with grooves on each side to receive the edges of the glass. - VILLAIN, or Villei N, in our ancient customs, denotes a man of servile and base condition, viz. a bondman or servant; and there were anciently two sorts of bondmen or villains in England; the one termed a villain in gross, who was imme- diately bound to the person of his lord and his heirs; the other, a villain regardant to a manor, he being bound to his lord as a member belonging and annexed to the manor whereof the lord was owner; and he was properly a pure villain, of whom the lord took redemption to marry his daughter, and to make him free ; and whom the lord might put out of his lands and tene- ments, goods and chattels, at his will, and beat and chastise, but not maim him. - VINEGAR, is a liquid of a reddish or yellowish colour, a pleasant sour taste, and an agreeable odour. Its specific gra- 1028 vo L v U L DictionARY of MECHANICAL scIENCE. vity varies from 1:0135 to 1.0251, and it differs also in its other properties, according to the liquid form in which it has been procured. It is very subject to decomposition; but Scheele discovered that if it is made to boil for a few moments, it may be kept afterwards for a long time without alteration. Besides acetic acid and water, vinegar contains several other ingre- dients, such as mucilage, tartar, a colouring matter, and often also two or more vegetable acids. When distilled at a tempe- rature not exceeding that of boiling water, till about two-thirds of it have passed over, all these impurities are left behind, and the product is pure acid diluted with water. See Acı D and CHEMISTRY. - VINERY, in Gardening, a sort of garden erection, consisting of a wall twelve or fourteen feet high, extending from east to west, furnished with stoves, flues, a roof, and lights of glass, for the protection and cultivation of vines. The double vinery, in the Plate, is an improvement on the old system, the advan- tages of which must appear obvious on inspection. The build- ings will be attended with some additional expense; but wher- ever a trial has been made, the experiment has fully answered every reasonable expectation. ViNEYARD, a plantation of vines. - VIOL, among sailors, the anchor rope, as it is thus pro- nounced, but which is more generally spelt voyol. This name is more particularly applied to a thick rope, which being attached to the cable, passes through a large block, and thence to the fore capstan : when it goes direct from the cable to the main capstan, it is more usually called the messenger. Viol, a stringed instrument, resembling in shape and tone the violin, of which it was the origin; that impressive and com- manding instrument being little more than an improvement of the old viol. - t VIOLA, a tenor violin. This instrument is similar in its tone and formation to the violin, but its dimensions are some- what greater, and its compass a fifth lower in the great scale of sounds. * * VIOLIN, or FIDDle, a well-known stringed instrument, of brilliant tone and active execution. The four strings of which it consists, are tuned in fifths from each other. The pitch of the lowest string is G, under the second ledger line in the treble stave; consequently that of the next is D, under the first line of the stave; the pitch of the next above that, A on the second space; and that of the upper string, E on the fourth space. VIOLOXCELLO, a bass viol, containing four strings, the lowest of which is tuned to double C. The strings are in fifths, consequently the pitch of that next the gravest is C gamut ; that of the next, D on the third line in the bass; and ... that of the upper string, A on the fifth line. s VISION. See OPTICS. - VITAL AIR. Pure air or oxygen, is one of the consti- tuent parts of atmospherical air, and is useful in the germi- nation of grain and seeds, the vegetation and growth of plants, and is essential, to the support of animal life. In reference to the latter, it is inhaled by respiration; but on the nature of its operation there have been many theories, each of which has its advocates and followers, without being supported by conclusive arguments, or established on incontrovertible principles. VITRIFICATION. See GLASS. WITRIOL, MARTIAL, or Sulphat of Iron. In commerce it is usually denominated green vitriol or copperas. It is not pre- pared by dissolving iron in sulphuric acid, but by moistening the pyrites, which are found native in abundance, and exposing , them to the open air. They are slowly covered with a crust of sulphat, of iron, which is dissolved in water, and afterwards obtained in crystals by evaporation. Sometimes the salt is found ready-formed, either in a state of solution in water, or mixed with decayed pyrites. In some cases it is found neces- sary to roast the pyrites before they can be made to undergo spontaneous decomposition. Sulphat of iron has a fine green colour. Its crystals are transparent rhomboidal prisms, the faces of which are rhombs, with angles of 79 deg. 50 min. and 100 deg. 10 min. inclined to each other at angles of 98 deg. 37 min. and 81 deg. 23 min. It has a very strong styptic taste, and always reddens vegetable blues. Its specific gravity is 1-8399. It is soluble in about two parts of cold water, and in #ths of its weight of boiling water. It is insoluble in alcohol. Volcanoes are peculiar to no climate, and have no necessary connexion with any other mountains, but seem to have some with the sea, being generally in its neighbourhood; they fre- quently throw out matter which belongs to the sea, as the relics of fishes, sea-weed, and sometimes sea-water itself. The most celebrated volcanoes are those of Etna and Vesuvius. WOLCANOES IN THE Moon. face mountains and valleys in common with the earth, some modern astronomers have discovered a still greater similarity, viz. that some of these are really volcanoes emitting fire as those on the earth do. An appearance of this kind was discovered some years ago by Don Ulloa in an eclipse of the sun. It was a small bright spot, like a star, near the margin of the moon, and which he at that time supposed to have been a hole, with the sun's light shining through it. Succeeding observations, however, have induced astronomers to attribute appearances of this kind to the eruption of volcanic fire; and Dr. Herschel has particularly observed several eruptions of the lunar volcanoes. VOLLEY of SMALL ARMs, a discharge of several muskets at the same instant. - VOLTAISM. See GALVANISM. VOLUNTEER, implies a man who, being in the vice, freely offers himself to serve in danger and fatigue. - VOLUTE, a spiral scroll, used in the Ionic and Composite capitals, whereof it makes the principal characteristic and Ornament. - - VORTEX, a whirlwind, or sudden rapid or violent motion of the air in gyrës or circles. Sometimes it implies an eddy or whirlpool, or a body of water, in certain seas, or rivers which runs rapidly around, forming a sort of cavity in the middle. WORTEX, in the Cartesian philosophy, is a system or col- lection of particles of matter, moving the same way, and round the same axis. WOWEL, in Grammar, a letter which affords a complete sound in itself. In our language there are six in number, a, e, i, o, u, and y. . & VOYAGE, any distance passed, or to be passed, at sea, VULCANIC THEORY OF THE EARTH. This theory, also called Plutonic, in opposition to the Neptunian theory, (which supposes all matter to have formerly been dissolved in a ſluid, and to have gradually been deposited in the forms in which we now find it,) supposes, that, formerly the world was in a fluid state, by the power of heat; on the abatement of which, rocks became solid; and that the inequalities of surface of hills and mountains have been caused by the force of inter- nal fire elevating them above the common level. It assumes that, at great depths in the mineral regions, an immense heat is constantly present, and that this heat operates in the fusion and the consolidation of the substances deposited. To the action of this heat, the formation of all our strata is attributed. They are conceived to be the wrecks of a former world, which have been more or less perfectly fused by this agent, and by subsequent cooling have been consolidated. The subterra- neous fire being placed at immense depths, the substances on which it operates must be under a vast pressure. This prevents their volatilization in whole or in part, and from this circum- stance it explains appearances, in minerals and qualities, which they possess, which would otherwise appear inconsistent with the supposition of their being formed by fire. - VULGATE, a very ancient Latin translation of the Bible, and the only one the church of Rome acknowledges authentic. It is by St. Jerome, and was made almost word for word from king’s ser- a particular expedition of the Greek of the LXX. The author of the version is not . known, nor so much as guessed at. * Vulgate of the New Testament.—This the Romanists generally hold preferable to the common Greek text, in regard it is this alone, and not the Greek text, that the Council of Trent had declared authentic. Accordingly that church has, as it were, adopted this edition. The priests read no other at the altar, the preachers quote no other in the pulpit, nor the divines in the schools. e VULTUR, the Vulture, in Natural History, a genus of birds of the order accipitres. As the moon has on its sur- VOLCANO, in Natural History, a burning mountain, or one- that occasionally vomits forth fire, flame, ashes, cinders, &c. \ *—º A. Front array 73ack. Wr //". B. Prix fºr a Cºxy of Fºy, or Peaches, ºn Pots, and Mºsh - rooms wido: them. Zh he fi/ed with freſh Zwig at the beginning of fwww.ny the Pºwer, which wiſ/ be of cºveruria/ service to the Pine, and evasure a crºp. A'W. 462 : Fe e t | E-T1H TETp | | | = = = | --- =- - wº- - - - - -- - - --w - | C. ſtone Pazz/ºr º - - • ' ** º D. Złowder" fºr rhe 77vacy fo raz, we . Zhe Fruit to ºn ow again.ºf the Back Wa/l. Graper fir flºw curring in April and ſºn'. E.6%ren Wied’ behind the Pºwery. F. Fire Hºnºr. DICTIONARY OF MECHANICAL SCIENCE. 1029 W. W, is the twenty-first letter of our alphabet. g WACKEN, a mineral that occurs in mass ; sometimes it forms strata, but more frequently it runs in veins. Colour dark greenish-gray, which often passes to mountain-green, or black- ish-green. Specific gravity from 25 to 2-9. Easily melts be- fore the blowpipe. WAD, or WADDING, in Gunnery, a stopple of paper, hay, straw, old rope-yarn, or tow, rolled up like a ball, or a short cylinder, and forced into a gun to keep the powder close in the chamber; or put up close to the shot, to keep it from rolling out. WAFERS. To MAKE :—Take very fine flour, mix it with white of eggs, isinglass, and a little yeast; mingle the mate- rials; beat them well together; spread the batter, being made thin with gum-water, on even tin plates, and dry them in a stove, then cut them out for use. You may make them of what colours you please, by tingeing the paste with brazil or vermilion for red; indigo or verditer, &c. for blue; saffron, turmeric, or gamboge, &c. for yellow. - WAFT, a signal displayed from the stern of a ship for some particular purpose, by hoisting the ensign furled up together into a long rolſ, to the head of its staff, or to the mizzen-peek. It is particularly used to summon the ship's boats off from the shore. WAGERS. In general a wager may be considered as legal, if it is not an incitement to a breach of the peace, or to immo- rality; or if it does not affect the feelings or interest of a third person, or expose him to ridicule; or if it is not against sound olicy. 3. p WAges, what is agreed upon by a master to be paid to a servant, or any other person that he hires to do his business for him. WAIST, that part of a ship which is contained between the quarter-deck and forecastle, being usually a hollow space, with an ascent of several steps to either of those places. When the waist of a merchant ship is only one or two steps of descent from the quarter-deck and forecastle, she is said to be galley- built; but when it is considerably deeper, as with six or seven steps, she is called frigate-built. - - WAist Cloths, coverings. of canvass or tarpauling for the hammocks, which are stowed on the gangways, between the quarter-deck and forecastle. WAISTERS, people stationed in the waist in working the ship; and as they have little else of duty but pulling and hoist- ing, they are, for the most part, selected from the strongest landsmen and ordinary seamen. WAKE of a SHIP, the smooth water astern when she is under sail ; this shews the way she has gone in the sea, whereby the mariners judge what way she makes. For if the wake is right astern, they conclude she makes her way forward, but if the wake is to leeward a point or two, then they conclude she falls to the leeward of her course. • WALE, or WALes, in a Ship, those outermost timbers in a ship's side, on which the sailors set their feet in ciimbing up. As the wales are framed of planks broader and thicker than the rest, they resemble ranges of hoops encircling the sides and bows. They are usually distinguished into the main-wale and the channel-wale ; the former is below the lower-deck ports, and the latter between the top of those ports and the sills of the upper-deck ports. The situation of the wales being ascertained by no invariable rule, is generally submitted to the judgment and fancy of the builder; but the position of the gun-ports and scuppers ought to be particularly considered, that the wales may not be wounded by too many breaches. g WALES, WILLIAM, a respectable mathematician, who accompanied Cook in his first voyage round the world, as astro- nomer, and was afterwards appointed mathematical master at Christ's hospital. He was author of an Account of Astronomi- cal Observations in the Southern Hemisphere, 4to, ; &c. Wales died in 1799, .* WALLIS, Dr. Joh N, an eminent English mathematician, was born at Ashford in Kent, in 1616, and died in Oxford in 1703, in the 88th year of his age. Dr. Wallis was the author of seve- ral ingenious and learned works, on various branches of the mathematics. * WALL-SIDED, the figure of a ship's side when, instead of being incurvated, so as to become gradually narrower towards the upper part, it is nearly perpendicular to the surface of the water, like a wall. In ship-building, this was formerly called wall-reared. WAPENTAKE, from the Saxon, the same with what we call a hundred, and more especially used in the northern coun- ties beyond the river Trent. - -- WAR. The too frequent recurrence of this great and detest- able calamity, unfortunately renders a definition of the word unnecessary. If we were called upon to define it, we would say, it is the wanton destruction, the cold-blooded slaughter, of the human race : we should call it an accumulation of every sin that degrades and vilifies mankind: we should mark it as a practice that diffuses misery, and perpetuates vice ; we should say, that if there is a burlesque upon the boasted reason of man, it is this—when millions meet to murder each other for a quar- rel, in which, in general, they have not individually the smallest interest. The poet who wrote “One murder makes a villain, millians a hero,” &c. deserves a statue of gold; and the writer of that verse may lift his head in the proudest assembly, and avow his principles in the face of the world. WARDEN, one who has the charge of keeping of any per- son or thing by office. - WARDMOTE, in London, is a court so called which is kept in every ward of the city. WARE, (To) or WEAR, to cause a ship to change her course from one board to the other, by turning her stern to the wind. Hence it is used in the same sense of veering, and in opposition to tacking, wherein the head is turned to the wind, and the stern to leeward. Since by this movement the ship loses considerably more ground than by tacking, it is rarely practised, except iu cases of necessity, or for delay, as when the violence of the wind and sea renders tacking impracticable, or when the course is slackened to wait for a pilot, or for some other ship, &c. In order to wear or veer the ship, the after sails are brailed up, or made to shiver in the wind, whilst the head sails are in- creased, the helm being put hard a-weather, or to windward : by which means the forepart is turned about from the wind; but as soon as the wind will act upon that quarter, which was before to leeward, the after sails must be extended so as to receive the greatest impulse, whilst the head sails are braced obliquely, whereby the vessel will wheel round, with her bow to windward, and become close-hauled upon the contrary tack to that on which she formerly stood. When the tempest is so violent as to prevent the use of sails, the effort of the wind operates almost equally on the opposite ends of the ship, so that the masts and yards situated at the head and stern coun- terbalance each other. The effect of the helm is also consi- derably diminished; because the head way, which gives life and vigour to all its operations, is at this time feeble and inef- fectual. Hence it is necessary to destroy this equilibrium, which subsists between the mast and yards afore and abaft, and to throw the balance forward in order to prepare for veer- ing or wearing. This is accordingly performed by bracing the foremost yards across the direction of the wind, and arrang- | ing those on the main mast and mizzen mast directly in the line of the wind. If this expedient proves unsuccessful, and it is absolutely necessary to wear, in order to save the ship from destruction by oversetting or running ashore, the mizzen mast must instantly be cut away, and even the main-mast, if she yet remains incapable of answerijg by bearing away before the wind. - 109. - 12 F 1030 TW. A. T W A T DICTIONARY OF MECHANICAL SCIENCE. WARP, in the Manufactures, is the threads, whether of silk, wool, linen, hemp, &c. that are extended lengthwise on the weaver's loom ; and across which the workman by means of his shuttle passes the threads of the woof, to form a cloth, rib- band, fustian, or other stuff. WARP, a rope or hawser. employed occasionally to remove a ship from one place to another in a port, road, or river. Hence, To Warp, is to change the situation of a ship, by pulling her from one part of a harbour, &c. to some other, by means of warps which are attached to buoys, to other ships, to anchors sunk in the bottom, or to certain stations upon the shore, as posts, rings, trees, &c. WARRANT, a praecippe, under hand and seal, to bring any offender before the person granting it; and warrants of com- mitment are issued by the privy council, a secretary of state, or justice of the peace, &c. when there has been a private informa- tion, or a witness has deposed against an offender. A warrant from any one of the justices of the Court of King's Bench extends over all the kingdom, and is tested or dated England, but a warrant of a justice of peace in one county, must be backed, that is, signed, by a justice of another county, before it can be executed there; and a warrant for apprehending an English or a Scotch offender, may be indorsed in the opposite kingdom, and the offender carried back to that part of the united king- dom in which the offence was committed. This is also now extended to Ireland, upon a proper certificate of an indictment or information filed in either country. - WARRANT of an Attorney, is an authority and power given by a client to his attorney, to appear or plead for him ; or to suffer judgment to pass against him by confessing the action by “ nil dicit, non sum informatus, &c.” WARRANT, the name given to a kind of commission or autho- rity to those officers appointed by the Navy-Board, while the authorities granted by the Admiralty are styled commissions. Hence, a Warrant Officer, is an officer holding a warrant from the Navy-Board ; such are the master, surgeon, purser, boats- wain, gunner, carpenter, &c. - - WARRANTY, a promise or covenant by deed, made by the bargainer, for himself and his heirs, to warrant or secure the bargainee and his heirs against all men, for the enjoying any thing agreed on between them. WARREN, is a franchise, or place privileged by prescription or grant from the king, for the keeping of beasts and fowls of the warren ; which are coneys, partridges, pheasants, &c. WASH, among Distillers, the fermentable liquor used by malt distillers. WASH Board, a broad thin plank, fixed occasionally on the top of a boat or other small vessel's side, so as to increase the height thereof, but may be removed at pleasure. It is used to prevent the sea from breaking into the vessel in rough weather. WASTE, is the committing of any spoil or destruction in - houses, lands, &c. by tenants, to the damage of the heir, or of him jn reversion or remainder; whereupon the writ or action of waste is brought for the recovery of the thing wasted, and damages for the waste. - - - WATCH, a small portable machine for measuring time; having its motion commonly regulated by a spiral spring. Per- haps, strictly speaking, watches are all such movements as shew the parts of time ; as clocks are such as publish them by strik- ing on a bell, &c. But commonly the term watch is appro- priated to such as are carried in the pocket; and clock to the large movements, whether they strike the hour or not. - Spring or Pendulum WATCH es, stand pretty much on the same principle with pendulum clocks. For if a pendulum describing small circular arcs, make vibrations of unequal lengths in equal times, it is because it describes the greater arc with a greater velocity; so a spring put in motion, and making greater and less vibrations as it is more or less stiff, and as it has a greater or less degree of motion given it, performs them nearly in equal times. Hence, as the vibrations of the pendu- lum had been applied to large clocks, to rectify the inequality of their motions; so to correct the unequal motions of the balance in watches, a spring is added, by the isochronism of whose vibrations the correction is to be effected. The spring is usually wound into a spiral ; that, in the little compass allotted it, it may be as long as possible; and may have strength enough not to be mastered, and dragged about by the inequalities of the balance it is to regulate. The vibrations of the two parts, viz. the spring and the balance, should be of the same length; but so adjusted, as that the spring, being more regular in the length of its vibrations than the balance, may occasionally com- municate its regularity to the latter. - - Striking Watches, are such as, besides the proper watch-part adapted to the measuring of time, have a clock part for striking the hours, &c. - Repeating Watches, are such as by pulling a string, &c. repeat the hour, quarter, or minute, at any time of the day or night. Of the Mechanism of a Watch, properly so called. Watches, as well as clocks, are composed of wheels and pinions, and a regulator to direct the quickness or slowness of the wheels, and of a spring which communicates motion to the whole machine. But the regulator and spring of a watch are vastly inferior to the weight and pendulum of a clock, neither of which can be employed in watches. Instead of a pendulum, therefore, we are obliged to use a balance (plate, fig. I,) to regulate the motion of a watch; and a spring, fig. 2, which serves instead of a weight to give motion to the wheels and balance. The wheels of a watch, like those of a clock, are placed in a frame formed of two plates and four pillars. Fig. 3, represents the inside of a watch, after the plate, fig. 4, is taken off. A is the barrel which contains the spring, fig. 2; the chain is rolled about the barrel, with one end of it fixed to the barrel A, fig. 5, and the other to the fusee B. - 'When a watch is wound up, the chain which was upon the barrel winds about the fusee, and by this means the spring is stretched; for the interior end of the spring is fixed by a hook to the immoveable axis about which the barrel revolves ; the exterior end of the spring is fixed to the inside of the barrel, which turns upon an axis. It is therefore easy to perceive how the spring extends itself, and how its elasticity forces the barrel to turn round, and consequently obliges the chain which is upon the fusee to unfold and turn the fusee; the motion of the fusee is communicated to the wheel C, fig. 5; then by means of the teeth to the pinion c, which carries the wheel D ; then to the pinion d, which carries the wheel E.; then to the pinion e, which carries the wheel F ; then to the pinion f, upon which is the balance wheel G, whose pivot runs in the pieces A called the potance, and B called a followcr, which are fixed on the plate fig. 4. This plate, of which only a part is represented, is applied to that of fig. 3, in such a manner that the pivots of the pinions enter into holes made in the plate, fig. 3. Thus the impressed force of the spring is communicated to the wheels ; and the pinion f being then connected to the wheel F, obliges it to turn fig. 5. This wheel acts upon the palettes of the verge 1, 2, fig. 1, the axis of which carries the balance H. H., fig. 1. The pivot I in the end of the verge, enters into the hole c in the potance A, fig. 4. In this figure the palettes are represented; but the balance is on the other side of the plate, as may be seen in fig. 6. The pivot 3 of the balance enters into a hole of the cock B C, fig. 7, a perspective view of which is represented in fig. 8. Thus the balance turns between the cock and the potance c, fig. 4, as in a kind of cage. The action of the balance wheel upon the palettes 1, 2, fig. 1, is the same with what we have described with regard to the same wheel in the clock i. e. in a watch, the balance wheel obliges the balance to vibrate backwards and forwards like a pendulum. At each vibration of the balance, a palette allows a tooth of the balance wheel to escape ; so that the quickness of the motion of the wheels is entirely determined by the quickness of the vibrations of the balance; and these vibrations of the balance and motion of the wheels are produced by the action of the spring. But the quickness or slowness of the vibrations of the balance depends not solely upon the action of the great Spring, but chiefly upon the action of the spring a, b, c, called the spiral spring, fig. 9, situated under the balance H, and represented in perspective, fig. 6. The exterior end of the spiral is fixed to the pin a, fig. 9. This pin is applied near the plate in a, fig. 6; the interior end of the spiral is fixed by a peg to the centre of the balance. Hence if the balance is turned upon itself, the plates remaining immoveable, the spring will extend itself, and make the balance perform one revolution. Now, after the spi- ral is thus extended, if the balance be left to itself, the elasticity - . - -- 2- . - º/ yº Zºº -/////ZZZZZZZZ/Z- % //, ///zzzzzzzzº Azzº. * - i - i. º º - - W. A T DICTIONARY OF w A T 1031 M ECH AN IC A. L SCIENCE. of the spiral will bring back the balance, and in this manner the alternate vibrations of the balance are produced. In fig. 5, all the wheels above described are represented in such a manner, that it may be easily perceived at first sight how the motion is communicated from the barrel to the balance. In fig. 10 are represented the wheels under the dial-plate by which the hands are moved. The pinion a is adjusted to the force of the prolonged pivot of the wheel D, fig. 5, and is called a cannon pinion. This wheel revolves in an hour. The end of the axis of the pinion a, upon which the minute hand is fixed, is square; the pinion fig. 10, is indented into the wheel b, which is carried by the pinion a. Fig. 11, is a wheel fixed upon a barrel, into the cavity of which the pinion a enters, and upon which it turns freely. This wheel revolves in twelve hours, and carries along with it the hour-hand. Such in brief is the general mechanism of a watch ; to treat the subject to the extent its importance demands would require a volume: some parts of the construction are further explained under the words-BALANCE and SCAPEMENT in this volume. Mr. Elliot of Clerkenwell has lately invented a very simple repeating watch, in which the motion is performed with much fewer parts than in the usual construction, by which means he is enabled to reduce the price so low as eight guineas for a good repeater on this principle, or to add the repeating work to another watch for three. The method by which this repeater is so much simplified is by the use of a single part, so contrived as to perform the ope- rations of several : this is a flat ring, or centreless wheel, of nearly the same diameter as the watch, supported in its place, so as to admit of circular motion, by four grooved pulleys placed round its external circumference, in the same manner as the part in common clocks which denotes the moon’s age. This part is put in motion by turning the pendant, whose extremity is formed into a small vertical wheel, which works in teeth cut on the external part of the flat ring for almost a third of its cir- cumference. The lower part of the ring contains the pins, at right angles to its face, which lift the hammers for striking the hours and quarters ; the internal part of the ring contains indentations of regularly increasing depths, which receiving the tails of the levers, whose other extremities are pressed by their springs against the hour-snail and the quarter-snail, is by them prevented from moving beyond a certain degree proper for the time : after the pendant is turned, the ring is brought back to its first position, by a box spring, round which a fine chain is coiled, whose extremity is connected with the inner part of the ring. By turning the pendant to the left the hour is struck, and by turning it to the right the quarters are repeated ; and the returning spring just mentioned is nade to operate in both directions, by its chain passing between two little pulleys, which on either side convert the direction of the chain to the line of traction of the spring. Hence it is evident this single flat ring performs all the following operations. 1. It receives the motion for striking the hour from the pendant. 2. The same for striking the quarters. 3. It carries the pins or teeth, which lift the hour-hammer. 4. The same for the quarter-hammer. 5. It contains the indentations by which the hour snail operates on it by its lever. 6. The same by which the quarter-snail ope- rates on it. 7. It carries the part that recoils the movement which tells the hour to its first position. 8. It carries the part for the same purpose, for the quarter movement. 9. It contains a cavity, which moves over a fixed pin, that prevents the pen- dant from turning it too far. In this ring, the same parts in three instances are made to perform double operations, by which simplicity of construction is advanced, apparently, to its greatest extent.—Dr. Gregory's Mechanics. WATCH, in the art of War, a number of men posted at any passage, or a company of the guards who go on the patrol. At Sea, the term watch denotes a measure or space of four hours, because half the ship's company watch and do duty in their turns, so long at a time, and they are termed starboard watch, and larboard watch. These epithets allude to the situation of their hammocks when hung up ; the two watches are, however, occasionally separated into three or four divisions, as in a road, for an anchor-watch, &c. But the officers of the navy usually divide themselves into three watches, in order to lighten their duty.—Starboard Watch, Hoay Starbow Lines, Hoay! Larboard Watch, Hoay ! Larbow Lines, Hoay ! are excla- mations used by the boatswain's mates when summoning their respective watches upon deck, to relieve each other. Anchor WATCH, is a small guard kept constantly upon deck, while the ship rides at single anchor. Dog Walches, are the two reliefs which take place between four and eight o'clock in the afternoon, each of which is only two hours; the intent of these watches is to change the turn of the night watch every twenty-four hours. The First Watch, is from eight o'clock in the evening till twelve at night. The Middle Watch continues from twelve till four in the morning. The Morning Watch comprehends from four to eight o'clock in the morning. See Nautical DAY, p. 214. A buoy is said to watch, when it cou- tinues floating upon the surface of the sea. WATCH, is also a word used in throwing the deep-sea lead, when each man, on letting go the last turn of line in his hand, calls to the next abaft him “Watch.” WATCH Glasses, are the glasses employed to measure the period of the watch, or to divide it into any number of equal parts, as hours, half-hours, &c. so that the several stations therein may be regularly kept and relieved, as at the helm, pump, look-out, &c. See the article GLAss. WATCHMAN’S NoctuARY, the name given to an instru- ment lately contrived to remedy a great defect in an important branch of the police of great cities, that of night-watching. Every twenty-four hours furnishes some instance of the ineffi- cacy of the present system, by the depredations which have been committed in the night, or by the fatal accidents which occur from a neglect of giving families timely warning in cases of sudden fires. A respectable magistrate (Samuel Day, Esq. of Charter House, Hinton, Somersetshire) has directed his at- tention to the application of a mechanical check upon the dili- gence and regularity of watchmen, labourers, and all other classes of men whose duty requires that they should attend at certain places at appointed times; the instrument he has invented for this purpose he calls a Watchman's Noctuary, or Labourer's Regulator. The invention consists principally of a large horizontal wheel, which is moved uniformly round every twelve hours by clock- work. The upper side of this wheel is divided by two circles, one within the other; the outer one, or periphery, having the hours and quarters marked on it, which may be called the late- ral side; the inner circle having also a dial, which may be called the vertical one. The space between these circles or dials is divided into cells, each cell corresponding with a quar- ter or half-hour of the different hours marked on the dials; and if thought proper, the cells might be so multiplied, as that each would correspond within a period of five minutes. Such is the upper side of the horizontal wheel, which may be made of cop- per, or tin, or various other materials, and is about 9 inches in diameter. The under side of the same has a brass wheel with teeth, diameter 34 inches, fixed to its central part; the teeth of which, letting in with those of a smaller wheel or pinion, give motion in consequence to the large horizontal wheel (of which it forms a part) by the motion it receives from the pinion. This pinion being set in motion by the common clock-work, and a weight or spring, the revolution of the horizontal wheel is com- pleted once in twelve hours, and thus regularly going round, will at all times shew the time of day or night. As it moves round it carries the cells above mentioned under a kind of chink, just large enough to receive a token of about the size of a far- thing. This chink sinks down from an external brass box, which is sufficiently large to admit a man's fingers to drop in the token by an external aperture or month of the chink, the token being directed perpendicularly through this chink into such cell as is immediately under it, and which must corre- spond with the time of night or day. The head of the case of the machine has double doors in front; the outward door covers the whole face together, leaving a sufficient space above the horizontal wheel for examining the tokens and taking them from the cells, or for removing the wheel when necessary. A smaller door opens in this large one upon the brass box abovementioned, the opening of which belongs solely to the watchman, or such other person as may be required to use the same, for the pur- pose of seeing the time and dropping his tokens, a minute dial also being placed under the hour-index. If it be found more T032 W A T W A. T DICTIONARY of MECHANICAL SCIENCE. convenient, a common dial plate, to shew the hours and minutes, may be placed instead of the minute dial. The great outer door first mentioned is to be opened only by the inspector or examiner of the tokens, and ought to be well secured; but for greater safety, both against thieves and weather, there is an inside door, in which the fore-mentioned brass box is fixed; and this inner door being opened, throws into view the horizontal wheel for the purpose just specified. These are the essential parts of the invention; the different appendages may be variously modified. One such instrument as this being placed at each end of a watchman’s round, it will be ascertained how the man continued his movements through the night, to a nicety of ten minutes (or less if required) at any period of the watch; and the slightest irregularity or omission will be detected the next morning by the person whose office it shall be to open the machine. No trick or fraud on the watchman's part can coun- teract the movement of the horizontal wheel comprising the cells into which the tokens are to be dropped ; each cell is, by this contrivance, like time itself, irrevocable when past: the watch- man has no command over it, and the whole will be a kind of speaking witness of his diligence and fidelity in going his rounds, answering the next mbrming to the exact periods he either was or ought to have been there. * , , The same machine will answer in custom-houses, ware-houses, banking-houses, manufactories, bleaching-grounds, and every place where watching or other attendance, to be useful, must be exact: even 'sentinels on military duty might be required to leave tokens as memorials of their vigilance. - Mr. Day obtained the usual patent for securing to himself the right of making and selling this instrument; yet surely not to the exclusion of others invented for the same purpose: for the late Marquis of Exeter informed the public years ago, through the medium of Nicholson's Philosophical Journal, that a clock for a similar purpose had been invented by Messrs. Boulton and Watt of Birmingham, which cost no more than thirty shillings. His lordship had then had two of them at Bur- leigh Hatl more than four years; and he gives the following description of them : “They go eight days, and have a face like a clock, but do not strike. The dial goes round, and the hour- finger is fixed : round the edge of the dial are moveable iron pins, corresponding with the quarters in each hour. A small hammer placed behind the hour-finger, when moved downwards, pushes into the dial one of the pins which happens to be under it at the time, which pin remains so abased until the dial nearly returns to the same place, when by an enclosed plane the pin is raised up into its first position. This gives time to have the machine examined in the morning, to see how many pins have been struck, and at what time they were pushed downwards. The hammer is moved by the pulling of a chain with a handle, like house-door bells, which, by cranks and wires, is attached to it. . I have one in my library, the handle is out of doors. The other machine is placed in a building at the other end of my premises.” WATER, a transparent fluid without colour, smell, or taste ; in a very small degree compressible; when pure, not liable to spontaneous change; liquid in the common temperature of our atmosphere, assuming a solid form at 32° Fahrenheit, and a gasseous at 212°, but returning unaltered to its liquid state on resuming any degree of heat between these points ; it is capa- ble of dissolving a greater number of natural bodies than any other fluid whatever, and especially those known by the name of the saline ; performing the most important functions in the vegetable and animal kingdoms, and entering largely into their compositions as a constituent part. Water exists, therefore, in three different states: in the solid state, or state of ice,—in the liquid, and in the state of vapour or steam. It assumes the solid form, as observed above, when cooled down to the temperature of 32°, in which state it increases in bulk, and hence exerts a prodigious expansive force, owing to the new arrangement of its particles, which assume a crystalline form, the crystals crossing each other at an angle of 60° or 120°. The specific gravity of ice is therefore less than that of water. When ice is exposed to a temperature above 32°, it absorbs caloric, which then becomes latent, and is con- verted into a liquid state, or that of water. At the temperature of 42°5, water is at its maximum of density ; and according to some accurate experiments upon water in this state, a French cubic foot of it weighs 70 pounds 223 grains French, which is. equal to 529452.9492 troy grains. An English cubic foot, at the same temperature, weighs 437.102.4946 grains troy. By pro- fessor Robinson’s experiments, it is ascertained, that a cubic foot of water, at the temperature of 55°, weighs 998.74 avoir- dupois ounces, of 437.5 grains troy each, or about 13 ounce less than 1000 ounces avoirdupois, which latter, however, is the usual estimate. When water is exposed to the temperature of 212°, it boils; and if this temperature be continued, the whole is converted into elastic vapour or steam. In this state it ex- pands to about 1800 times its bulk when in the state of water, which shews what an astonishing expansive force it must exert when it is confined; and hence its application to the steam- engine, of which it is the moving power. To ascertain the Contraction and Expansion of Water in Cool- ing.—Fill a thermometer tube with tepid water, and immerse it in a glass vessel containing water of the same temperature, in which a mercurial thermometer is placed. If the whole appa- ratus be now placed in a bed of snow, or in a frigorific mixture, the water in the tube will gradually contract, till the mercury shews the temperature of 40°; it will then begin to expand gra- dually until it becomes ice. From this simple experiment the reader may see, what is otherwise, however, a well established fact, that the specific gravity of water is greatest at 42°. The expansion of this fluid when cooled still further, is an exception to the general law of bodies expanding by heat and contracting by cold ; and as we are unable to account for it, or refer it to any class of facts, it seems like a perpetual miracle, and may excite both our wonder and our gratitude whenever it is con- templated. It is in consequence of this miracle that ice swims on water, and does not sink down, choking up the streams and . stopping the currents of the rivers, the continued flow of which is as necessary to the existence of the world as the circulation of blood is to our existence. Rules for ascertaining the Impurity of Water. Water is rarely found in a perfectly pure state. It almost invariably contains some portion of earthy, saline, vegetable, animal, or metallic matter, which is derived from the substances over or through which it flows. These substances being more or Jess held in solution, filtration will of course only separate that which is undissolved and floating in it; ignorant persons should not therefore conclude because water has been filtered, that it is pure and fit for drinking ; as it might contain a deadly quan- tity of lead in solution, and yet be perfectly bright and transpa- rent. Most waters, however, that are turbid only require filtra- tion to render them salubrious. The most certain and direct way of purifying water is by distilling it with some fresh char- coal. The impurity of water may be ascertained by comparing it with that which is known to be pure, or distilled water. Im- pure water is heavier than pure water. Impure water is thinner, has less fluidity, than pure water. Impure water has some taste, colour, or smell,—pure water has none. Impure water, that contains earthy and metallic salts, is called hard water, being not so soft to the touch as pure water, nor does it wet any substance so readily as pure water. In country places, where water is both plentiful and good, these distinc- tions may be deemed unimportant; but the impurity of water in some situations is of very serious moment, and felt (we believe) very generally throughout the metropolis. In Christ Church, Surrey, it is a subject of as much complaint, perhaps, as any where. The water as supplied from some of the metropolitan water-works is so grossly impure, that, in the absence of filter- ing, it can only be safely used in food or drink after it has been boiled, recooled, and allowed to settle for some time—a process which is not only attended with considerable trouble, but which necessarily deteriorates the quality of the water. The following is a description of a method of filtering which may easily be adopted: Procure a cask somewhat less than a porter hogshead, but of a different shape, in order to give the bet- ter effect to the filtering process, being 40 inches deep on end, and 20 inches in diameter at the top and bottom. Make then a second or false bottom, and perforate it by a three-quarter inch gouge with about 18 boles; groove it into the cask, about four inches from the undermost or real bottom, and cover it over with four plies of coarse tiamuel. Procure a quantity of coarse | | | | | | | | R - %22%22z/ º/. Z. º -- ~ /// /// == = =/ / / - = - | | | - | | | | | - - - - | | | | Nº. - | . | | T | | |ºl |ºm | | |\º || || | º' W. | | * \ | , , , ºf " | | | Mºumi | | - | = re- = - | | | | - | | "|| - | | | " . | zº º = - º = | | | =| | | --~- == 2. Z …// P W. A. T W A T 1033 DICTIONARY OF MECHANICAL SCIENCE. j fresh-water sand, and with this fill the cask to the height of 20 inches from the false bottom, beating it hard down as it is put in. Above the sand insert another false bottom, perforated like the former, but not grooved into the cask; and over that again lay two plies of ſlannel. Then add layers of sand and pounded charcoal alternately, for the height of ten inches more, and above these place a lid, perforated and covered with flannel, like the two false bottoms. The six inches of the cask which are now left unoccupied, appropriate to the water to be filtered: a space equal to the reception of from 8 to 10 gallons. On making an experiment with the filter thus constructed, it will be found that the water, however impure when first put in, comes out as clear and sparkling as crystal ; and on a continued trial, there may be procured in this way more than twenty gallons of such water every twelve hours... The water may be produced of even greater purity, were it made to percolate upwards instead of downwards; we might, therefore, have our apparatus altered to one of the improved description represented in the annexed sketch. Description.—No. 1 is a cask, 40 inches deep by 20 in diame- ter, to be filled with water from the cistern W. No. 2, another cask of the same capacity, to contain the filter. B, the first false bottom, perforated and covered with flannel. D, the height to which the cask (No 2,) should be filled with sand,' and at which the second false bottom should be inserted. E, the lid, between which and D equal quantities of sand and charcoal are to be interposed. C, communicating cock between the two barrels. A, a cock, to discharge the pure filtered water. F., a l IT || l vessel to receive the water. G, the false bottom to be grooved into the cask No. 2. H, a ball-cock to regulate the filling of the cask No. 1. * An apparatus of the kind we have described, must obviously have great advantages over any filter that can be made of stone. By removing the upper lid E, whatever refuse may gather on the top, can be skimmed off occasionally. New layers of sand and charcoal, too, can be introduced with great ease, so that the apparatus can with very little trouble be kept at all times in tolerably efficient action, and may at a little expense be renovated entirely, whenever that is found necessary. All the stone filters, on the contrary, that we have ever seen, get rapidly clogged with the earthy deposits from the water, and if not fre- quently cleaned out, soon cease running altogether. It is de- serving of remark, that when the water is suffered to remain in the filter for any considerable time, it is apt to acquire a rank taste. It should be drawn off regularly at short intervals, or, which is better, by the emission of a constant stream. Finding of Water by the Divining Rod, is said to be practised in the following manner:—A green bunch of hazel or thorn is cut with a fork like the ſetter Y at its upper end; the water finder takes hold of the two prongs of the fork with both had ds held together in front of him, keeping the rod in an horizontal position, walking over the ground in this manner where a well is proposed to be sunk. When he comes over the spot where water is to be found, the thick end of the rod is observed to dip so decidedly, that no mistake ever arises from the indication. WATER CLos ET. Description of an Improved one, invented by Mr. Jordan, of Norwich. Essential as water closets are to the cleanliness and comfort of our dwellings, it was not until that extremely simple, but useful contrivance, known by the name of the water lute, or, as it is commonly called, the stink trap, was appº, to them, that the premises could be even partially secured from being annoyed with unpleasant and noisome efflu- via. In the country this evil was avoided by placing the water- closet in the garden : but in large towns there was no remedy, except frequent rinsing. But notwithstanding the defence afforded by the water-lute, these indispensable requisites con- tinued to be an annoyance, from the soil sometimes accumulat- ing in the pan of the stink trap, so that the necessity of rinsing with water became frequent—an operation which servants, how- -ever urged to it, would often neglect. An apparatus, calculated to perform this office, either by being put into action by the use of the closet, or that might, easily be made to act on such an occasion by the hand, was, in génsequence, long a desideratum and this desideratum was at låst supplied to a certain extent by the late Mr. Bramah, to whom the world is indebted for that most powerful machine, the hydraulic press. * Bramah's water-closet is two well known to need any parti- lar description in this place, having become one of the appen- dages, in general use, in all modern mansions; and could the occupiers always count upon their servants possessing even a very small portion of mechanical knowledge, it would have proved more efficient than it has done. But owing to this lack of knowledge, very slight causes, as all builders and plumbers. well know, not only impede.at times its due action, but expose the premises to be inundated by the continued flow of the cis- tern or reservoir employed to supply the water, occasioned by any bit of paper or other substance happening to lodge in the valve. • * * * Jordan's water closet, requires only to be made known to architects and builders, who may be allowed, generally speak- ing, to be the most competent judges of the value of any im- provement of this nature, to insure its general adoption in all new erections. We have not mentioned as any defect in Mr. Bramah's apparatus, the stretching of the copper-wires that connect the cranks by which action is given to the valve and trap pan, and which stretching at last-deranges the apparatus; because it is not a fair objection against any piece of mechanism to say, that in course of time it will need to be repaired. But when another apparatus offers itself to notice, it becomes a matter of common prudence to compare the two in point of durability, as well as general efficiency. sº * Jordan has taken out a patent for his new apparatus, and the following particulars, extracted from his specification, will make the arrangement and structure of his machine familiar to our mechanical readers. We have only to premise, that where the same letters occur in more than one of the figures of the plate, they refer in both to the same parts. Jordan has discarded from his apparatus the valves, cranks, and connecting wires em- ployed in shutting off or opening the communication between the reservoir and the basin, or soil-pan, in the best water clo- set now in common use, and instead thereof, he uses what is known among engineers by the name of a three-way cock, and also a secondary or intermediate air-tight reservoir, made of copper, or other convenient material, and posited between the main reservoir and the pan or bason. To this cock, action is given by a lever, pressed down a little way by the seat, when the closet is being made use of, which causes the plug of the cock to make about a sixth part of a revolution in its shell or barrel, thereby opening a communication between the main reservoir and the secondary reservoir, and supplying the latter with a sufficient charge of water for the present occasion, while simul- taneously, by the same movement of the cock, the communica- tion is shut off between the secondary reservoir and the bason. In this apparatus, the pan or bason A, fig. 1, is fixed in its place in the usual manner. The water for rinsing it is admitted by the aperture B, from the secondary reservoir R, through the three-way-cock'C, which is represented in that position in which it is left after the pressure is removed from the seat, and after the water (having been admitted from the secondary reservoir through the cock C, into the bason or pan A,) has performed its duty-the communication being still open between the pam or bason and the secondary reservoir, which is then empty. For the convenience of description, the pan A is represented with- out the usual boxing or enclosure, and without either the cover or the sinking seat. Let the seat be conceived to be attached to its place by hinges, in the usual manner, and resting in front on the top of the rod F, then, (as may be seen by inspecting the 12 G. e 1034 W. A. T. w DICTIONARY OF MECHANICAL scIENCE. 'W' A T drawing,) the seat on being pressed down, wiil cause the rod. F to descend, and give motion to the lever G, H, which being connected with the lever or handle I of the three-way cock, by the intermediate rod K, will cause the handle I to describe an are a, d, upwards to d, pointed to by the dotted outline of the handle or lever I in its elevated position,) and will keep it in that elevated position till the pressure be removed from the top of the rod F, when by the action of the spring Q, it will be brought back to its first situation. employed to give the requisite action to this part of the appa- ratus; the patentee, however, does not rest the utility of his invention on the particular structure of the connecting parts of his machinery, but on the employnxent of the three-way cock in place of the valves and cranks hitherto used in water-closets, and on the employment of his secondary reservoir. But in whatever way motion be given to the plug of the three-way cock to cause it to make about a sixth part of a revolution, as above stated, the communication between the secondary reser- voir R, and a pan or bason A, is thereby shut off, and a com- munication is simultaneously opened between the reservoir R. and the supply pipe P, which supply pipe is brought by any convenient course from the main reservoir, wherever it may be situated at some higher position. This last-mentioned com- munication being now open, the water descends from the main reservoir through the supply-pipe P, passes through the cock C and the pipe D, and then ascends into the secondary reser- voir R, by which a degree of compression is given to the air contained therein, proportioned to the greater height of the water in the main reservoir. During the time that a person is on the sinking seat, the secondary reservoir receives its charge of water in the manner just mentioned, and is put in readiness to have the same discharged with considerable velocity, by the elasticity of the confined air, whenever the person rises from the seat; the compressed air, by its elastic force, then urg- | ing the water through the aperture B into the pan A, whence it removes the soil through the Stink-trap T, to the soil pipe U, to be carried off to the cess pool. The foregoing is what the patentee calls the more favourable arrangement and form of his apparatus—he prefers and adopts, however, another construction when circumstances will permit it, that is, when the main reservoir is sufficiently elevated to press the air contained above the surface of the water in the secon- dary reservoir, with the weight of a column of water of about ten or twelve feet in height. But when the main reservoir is not suffi- ciently elevated to give that degree of compression to the air which is required for an efficient quick expulsion of the water, he places the secondary reservoir as high as circumstances will permit, (four or five feet at least, but more if possible,) that he may establish a column of water between it and the pan A, to act by its mere weight as an impelling power, (when the cock C is put in its requisite position,) to force the water to pass from the secondary reservoir into A, with a proportioned velocity. That is, in this place he does not employ it air-tight, but open to the atmosphere. That this may be the more easily understood, see plate, fig. 2, in which the communication is open between the secondary reser- voir and the injection pipe N, the water being discharged, or having been injected through the pipe N into the pan or bason at A, by its own weight, under the common pressure of the atmosphere, acting upon it at the open orifice of the pipe or tube S, which ascends from the secondary reservoir through the main reservoir M. M., almost to its top, which is open to the atmosphere. This pipe S answers also another good purpose, in certain circumstances; namely, when the main reservoir M. M. receives its supply from any source which at particular times, or by any accident, may cause an overflow, (and which often causes great damage,) the tube or pipe S then serving as a waste pipe to carry off the surplus waste through the secondary reser- voir R, the pipe D, the cock C, and the injection pipe N, all of which, as has already been stated, are open so long as the sinking seat is not pressed on—that is, in other words, so long as the rod F (fig. 1,) is not depressed in such a manner as to turn the handle of the cock C, into the position marked by the dotted outline thereof. And here let it be observed, that as often as the position of the plug is altered, by depressing the end G, and piment, Roman ochre, Italian pink, king’s yellows. elevating the end H of the lever G. H., fig. 1, the cock is brought back again to its former position by the action of the spring Q 9 as soon as the pressure is removed from the top of the rod F. We need hardly notice, what is common to every similar eombination of parts, namely, that the usual means of simple joints are employed in the said apparatus to facilitate motion, where necessary, at the junctions of the levers and rods, as at a, b, and e, and at the fulcrum c, of the lever G H, as may be seen by inspecting fig. 1. - - Any machinist will see that different contrivances may be Mr. Jordan has also introduced another improvement into the three-way cock, which should not pass without notice, as it may be applied with advantage to other purposes. It is simple, but at the same time very effectual in giving a quick passage to the water. He makes the shell or barrel, and plug of the cock, about 5% inches long and about 2 inches diameter at oue end, and 1% inch at the other; and instead of cutting out of the plug such a piece as ºn, fig. 3, he removes a long piece n, as shewn in fig. 4. - One great advantage that attends the invention is, that where several water-closets may be required in large private build- ings, in prisons, hospitals, or extensive manufactories, only one general reservoir is required, nor will the premises ever need to be loaded with any other water than that in the one main reser- voir, all the secondary reservoirs being empty whenever the apparatus is not in operation. For the service of any number of water-closets, it is only necessary to connect a pipe for each, with the supply-pipe P, in order to convey water into the secon- dary reservoir appropriated to each closet respectively; and such is the convenience in fixing this apparatus, resulting from its simplicity, that these pipes, connected with the supply pipe P, may be carried in any direction—as behind skirting boards, up dark corners, or in any other course that may occasion the least cutting of walls or of floors—provided only that the closet be posited at the required depth below the main reservoir. The secondary reservoir is commonly made about 8 inches in dia- meter, and 2 feet long : the pipe P is common #-inch lead pipe, inside diameter; the pipe D about 1% inch diameter; and the injection pipe N not less in its sumallest part. The soil-pipe U is of the usual dimensions, namely, about four inches in dia- meter. \ WATER Bailiff, is an officer in sea-port towns, appointed for the searching of silips; and in London the water bailiff has the supervising and search of fish brought thither, and the gather- ing of the toll arising from the Thames; his office is likewise to arrest men for debt, &c. or other personal or criminal matters upon the river Thames. & WATER Colours. The general or simple colours, and the vari- ous species of each, fit for painting in water colours, are as fol- low : - - Whites : Constant white, white lead, flake white. Blacks : ivory black, lamp black. Greens: green bice, sap green. Blues : indigo, smalt, Prussian blue, ultramarine, ultramarine ashes. Browns: umber, burnt umber, bistre, burnt terra de sienna, unburnt ditto. Reds : burnt ochre, Indian red, lake, vermilion, carmine, Indian lake. Yellows: English ochre, gamboge, or- WATER Course. A water course does not begin by prescrip- tion or assent, but begins ea jure natura, having this course naturally, and cannot be diverted. WATER Borne, the state of a ship with regard to the water surrounding her bottom, when there is barely a sufficient depth of it to float her off the ground. WATER Lines, horizontal lines, supposed to be drawn about the outside of the ship's bottom, close to the surface of the water on which she floats; they are, accordingly, higher or lower upon the bottom, in proportion to the Septh of the column of water required to float her. - WATER-logged, the state of a ship, when, by receiving a great quantity of water into her hold, by leaking, &c. she has become heavy and inactive upon the sea, so as to yield without resistance to the efforts of every wave rushing over her decks. In this dangerous situation there is no resource for the crew, except to free her by the pumps, or to abandon her by getting into the boats; for the centre of gravity is no longer fixed, but fluctuating from place to place; the ship entirely loses her stability, and is almost totally deprived of the use of her sails, f w A T W A T , 1035 DICTIONARY OF ME CH AN ICAL SCIENCE. which may only operate to accelerate her destruction by over- setting her, or pressing the head under water. WATER Mill, See MechANICS. f - WATER Sail, a small sail spread occasionally under the lower studding sail or driver boom, in a fair wind and smooth | e g - aldermen have great power in governing the company of water- S C &l. . WATER Spout. See Spout. - - WATER Ways, long pieces of timber serving to connect the sides of a ship to her decks, and form a channel to carry off the water from the latter by means of scuppers. . WATER Works, in general, denote all manner of machines, moved by, or employed in raising or sustaining water; in which sense water-mills of all kinds, sluices, aqueducts, &c. may be called water-works. - - . WATER Wheel, the wheel of a water-mill, on which the water , acts as a first mover. - - WATERING PLAce, in a nautical sense, is a situation where boats can load fresh water for the use of a ship. There is nothing contributes more to the health of seamen than plenty of fresh water. This is an observation made by the great Captain Cook, who is entitled to perpetual remembrance, not more for his nautical talents and the large additions which he has made to the stock of geographical knowledge, than for the humanity which he displayed on all occasions; but in no instance so conspicuously as in his unwearied attentions to the preservation of the health of seamen. It is, therefore, an object of no small importance to discover how water may be prevented from becoming putrid, or be corrected and restored after it has become putrid, during long voyages. Accordingly, the Society for the Encouragement of Arts, &c. deemed this al proper subject for one of the prize questions. It appears, from some late experiments, that foul water may be rendered sweet and pure by means of charcoal powder and quicklime. The following observations on this subject are extracted from a number of Crell’s Chemical Journal, English translation:–“ The correction or restoration of putrid water by means of charcoal is so easy, so simple, and so cheap a process, that it deserves to be preferred to all other methods hitherto proposed. In all experiments that have been made, it has been found that charcoal powder, added in greater or less proportion, according to the degree of putrefaction, and the quantity of putrid particles, renders foul water sweet by agita- tion therewith for a few minutes. The subsequent separation of the charcoal from the water is eſſected with little diſficulty. The employment of quicklime, in conjunction with charcoal, is found to contribute considerably to the purification of foul water, especially if the water abound with extractive matter, which the quicklime precipitates, and thereby fines the water, and renders it perfectly clear. But the bad sumell of the water cannot be taken off by lime alone. The purifying operation of quicklime in conjunction with charcoal is most striking in the case.of water in which flax has been suffered to putrefy ; such water has an highly offensive smell. . That which was used in these experiments was as black as ink; by addition of quick- lime it was soon rendered quite clear and limpid, the lime carry- ing down with it black flakes to the bottom of the vessel; but the bad smell, instead of being removed, was made worse, and could only be got rid of by the addition of the charcoal powder. Water in which cabbage has been steeped, and which was of a yełłowish brown colour, was in like manner rendered fine and clear by quicklime, but did not part with its stinking smell till charcoal was mixed with it. “For the separation of the portion of lime which, in this mode of purification, remains dissolved in the water, it is pro- posed to employ, (in preference to fixed air) either acid of tartar or vitriolic acid. Water that has undergone putrefaction is deprived of its fresh and brisk taste, which charcoal is not capable of restoring ; hence the water that has been thus puri- fied tastes soft and vapid. For the restoration of its pleasant refreshing taste, fixed air is recommended to be mixed with it. The disagreeable mouldy taste which some waters have in their natural state may be corrected by simple filtration through charcoal powder; which has this farther advantage, that it separates at the same time all extraneous matter that is mechanically mixed with the water, and thereby renders it pure and clear. Water that has been kept mixed with charcoal for a whole year was not perceived to have the feast putrid smell. Hence it is proposed to make trial of charcoal in sea voyages. It is farther proposed to correct, by the same means, the bilge water which so much contaminates the whole air in ships.” WATERMEN. In London, the lord mayor and court of men, and appointing the fares for plying on the river Thames; and justices for Middlesex, and other adjoining counties, have also power to hear and determine offences, &c. See 10 G. II. C. 31. - WATT, JAMEs, Esq. F. R. S., born in Greenock, in the year 1736, was educated in the public schools of his native town; his partiality for the scientific arts soon developed itself, and at the age of eighteen he went to London, and placed himself under the tuition of an eminent mathematical instrument-maker, but ill-health occasioned his return to Greenock in about a year ; and this appears to be the only instruction he ever received.—all the rest was self-acquired: but so early had his talents developed themselves, that in 1757, when he was in his 21st year, he was appointed mathematical instrument-maker to the university of Glasgow, with apartments in the college. From these he removed to the city of Glasgow, in 1764, and in that and the subsequent year he invented his improvements on the steam-engine ; but circumstances delayed his taking out a patent until the year 1769. From the time of this invention, until the year 1774, he followed the profession of a civil engi- neer, at Glasgow, and made many surveys of canals and har- bours; several of the former of which have been carried into execution. The fortunate circumstance of his undertaking the repairs of a model of a steam-engine, in itself of so little im- portance, led to one of the greatest revolutions in mechanics that has taken place by any one invention since the records of history. See STEAM ENGINE. - A gentleman of some property and considerable knowledge, Dr. Roebuck, who was capable of appreciating the merit both of the inventor and of the invention, at last united himself with Mr. Watt, in the enterprise of bringing the matter to perfection: but his means were unequal to the purpose ; and after expend- ing all he could afford, the affair was on the point of being abandoned, when Mr. Boulton the great Birmingham manufac- turer, heard of the invention. Few men were more capable than Matthew Boulton of appreciating the value of Mr. Watt’s disco- very, and none more disposed to engage in a liberal manner in the enterprise. To a generous and an ardent mind, Mr. Boulton added an uncommon spirit for undertaking what was great and diffi- cult. Perhaps if Mr. Watt had searched all Europe, he could not have found another person so fitted in every way to assist in bringing the invention to bear. Mr. Boulton had money at command ; he was a man of address and influence, and advan- tageously known to the world: in short, he was just the person who was wanted; and after reimbursing Dr. Roebuck for his expenditure and loss, he became partner with Mr. Watt, who removed to Birmingham. In 1779, while Mr. Watt’s grand invention of the steam-engine was gradually improving, he con- trived the machine for copying letters by means of a thin moist paper and two rollers. It is a minor invention, though very useful, and one by which, to use his own words, time, labour, and money are saved ; despatch and accuracy are attained ; and secrecy is preserved. It has got into general use all over the world, and gives Mr. Watt another claim to the gratitude of mankind. The life of a sedentary or studious man produces few incidents; but in particular, when, like Mr. Watt, he hap- pens not to live amongst a society where he can associate much with others of a similar cast. Birmingham, or the country round, afforded few men who were calculated to associate with Mr. Watt; accordingly he was almost constantly at home, and very seldom in company. He had for a number of years quitted business, having acquired an independence, and having a son to continue the manufactory, with the son of Mr. Boulton. Mir. Watt was a Fellow of the Royal Society of London, and a mem- ber of the Institute of Paris; and there is not any body of learned or scientific men in Europe, that would not have thought his being admitted into their number an honour conferred upon them. He died at the age of eighty-four, at his house at Heath- field near Birmingham, having enjoyed is usual health and spirits almost to the last. 1036 W A T w R A DICTIONARY OF MECHANICAL SCIENCE. WAVE, in Physics, a volume of water elevated by the action of the wind, &c. upon its surface, into a state of fluctuation, and accompanied by a cavity. The extent from the bottom, or lowest point of one cavity, and across the elevation, to the 'bottom of the next cavity, is the breadth of the wave. Waves are considered as of two kinds, which may be distinguished from one another by the names of natural and accidental waves. The natural waves are those which are regularly proportioned in size to the strength of the wind which produces them. The accidental waves are those occasioned by the winds reacting upon itself by repercussion from hills or high shores, and by the dashing of the waves themselves, otherwise of the natural kind, against rocks and shoals; by which means those waves acquire an elevation much above what they can have in their natural state. . Motion of the Waves.—This makes an article in the Newtonian philosophy, that author having explained their motions, and calculated their velocity from mathematical principles, similar to the motion of a pendulum, and to the reciprocation of Water in the two legs of a bent and inverted syphon or tube. His propositions concerning such canal, or tube, is the forty-fourth of the second book of his Principia, and is this: “If water ascend and descend alternately in the erected legs of a canal or pipe ; and a pendulum be constructed whose length, between the point of suspension and the centre of oscillation, is equal to half the length of the water in the canal; then the water will ascend and descend in the same time in which the pendulum oscillates.” The author hence infers, in prop. 45, that the velocity of waves is in the subduplicate ratio of their breadths; and in prop. 46, he proceeds to find the velocity of waves, as follows: “Let a pendulum be constructed whose length between the point of suspension and the centre of oscillation is equal to the breadth of the waves, and in the time that the pendulum will perform one single oscillation the waves will advance forward nearly a space equal to their breadth. That which is called the breadth of the waves being the transverse measure lying between the deepest part of the hollows, or between the tops of the ridges.” Let A B C DE F represent a stagnant water ascending and descending in successive waves. Also let A, C, E, &c. be the tops of ths waves; and B, D, F, &c. the intermediate hollows. Because the motion of the waves is carried on by the successive ascent º and descent of the wa- "Tº ter; so that the parts of IG .D F it, as A, C, E, &c. which - º are highest at one time, become lowest immediately after, and because the motive force, by which the highest parts descend and the lowest ascend, is the weight of the elevated water, that alternate ascent and descent will be analogous to the reciprocal motion of the water in the canal, and observe the same laws as to the times of its ascent and descent, and therefore, (by prop. 44, above mentioned,) if the distances between the highest places of the waves A, C, E, and the lowest B, D, E, be equal to twice the length of any pendulum, the highest parts, A, C, E, will become the lowest in the time of one oscillation, and in the time of another oscillation will ascend again. Therefore between the passage of each wave, the time of two oscilla- tions will intervene; that is, the wave will describe its breadth in the time that the pendulum will oscillate twice; but a pendu- lum of four times that length, and which therefore is equal to ºu of the waves, will just oscillate once in that time, . E. I. - - Corol. 1, Therefore waves, whose breadth is equal to 39; inches, or 3; feet, will advance through a space equal to their breadth in one second of time ; and therefore in one minute they will go over a space of of 1953 feet; and in an hour a space of 11737 feet nearly, or two miles and almost a quarter. Corol. 2. And the velocity of greater or less waves will be augmented or diminished in the subduplicate ratio of their breadth. - But waves never emerge and sink again in the same place. They seem to take their origin from some agitated spot, and appear thence to advance in expanding concentric circles. The subaqueous propulsion accompanying them decides no of trees and other vegetable substances that contain it. doubt the direction of their progress, and prevents them from remaining in a pendulous state. If we examine attentively the motion of a wave, we shall find that the fore-part is always in the act of rising, while the hinder part is constantly sinking. The whole system hence appears to roll onwards, though there is actually no translocation of any portion of the mass, and each particle in succession merely oscillates with nearly a vertical ascent and descent. The motions of waves are per- fectly imitated on the stage, by turning slowly an open helical screw applied round an horizontal axis. This effect is pro- duced by the varying rate of the vertical elevation and depres- sion, which must be as the versed sine of the distance of each point from the summit. Its celerity is greatest in emerging from the level of the water; it becomes stationary when it has gained its utmost ascent; but it again acquires an equal and opposite celerity as it sinks under that level, till it comes to pause at the limit of depression. The figure and apparent motion of a wave hence result from this unequal and recipro- cating vertical play 9f each particle, combined with the con- tinued and uniform advance of the inciting energy. . WAX. The upper surface of the leaves of many trees is covered with a varnish which may be separated and obtained in a state of purity, and found to possess all the properties of bees-wax ; hence it is justly inferred that wax is a vegetable product, and that the bees extract it unaltered from the leaves Seve- ral plants contain wax in such abundance as to make it worth while to extract it from them. . WAY, a road or passage. A way may be by prescription, as if the owner and occupiers of such a farm have immemorially used to cross another's ground ; for this immemorial usage sup- plies an original grant. A right of way may also arise by act and operation of law; for if a man grants to another a piece of ground in the middle of his field, he at the same time tacitly gives him a way to come at it, for where the law gives any thing to any person, it gives by implication whatever is necessary for enjoying the same. - - WAY of A SHIP, the course or progress which she makes on the water when under sail. Thus, when she begins her motion, she is said to be under way; and when that motion increases, she is said to have fresh way through the water. Hence also, she is said to have head way, or stern way, to gather way, or to lose-way, &c. WAYGHTES, or WAITs. This noun formerly signified haut- boys; and which is remarkable, has no singular number. From the instruments, its signification was, after a time, transferred to the performers themselves; who being in the habit of parading the streets by night with their music, occasioned the name to be applied generally to all musicians who followed a similar practice. Hence those persons who annually, at the approach of Christmas, salute us with their nocturnal concerts, were and are to this day called wayghtes. - WEATHER, the state of the atmosphere with regard to the degree of wind, to heat or cold, or to dryness and moisture, but particularly to the first. Mr. Kirwan, in vol. v. of the Tran- sactions of the Irish Academy, has laid down the following rules, as the result of a careful examination of observations which had been made in England, during a period of 112 years. 1. When no storm has either preceded or followed the vernal equinox, the succeeding summer is generally dry, or at least so, five times out of six. " .. - 2. If a storm happen from an easterly point, on the 19th, 20th, or 21st day of May, the ensuing summer will, four times in five, be also dry. The same event generally takes place, if a storm arise on the 25th, 26th, or 27th days of March, in any point of the compass. 3. Should there be a storm, either at south-west or at west- south-west, on the 19th, 20th, 21st, or 22d of March, the follow- ing summer is wet, five times out of six. In England, if the winters and springs be dry, they are generally warm : on the contrary, dry summers and autumns. are usually hot ; as moist summers are cold. Thus, if the humidity or dryness of a particular season be determined, a tolerably correct idea may be formed respecting its tempera- ture. To these indications may be added the following unax- ims ; which, being the result of observations inade by accurate W E A w E"A 1037 DICTIONARY OF MECHANICAL SCIENCE. inquirers; may so far be depended upon, as they will afford a | criterion of the mildness or severity, and of the dryness or moisture, of future seasons. 1. A moist autumn, succeeded by a mild winter, is generally followed by a dry and cold spring; in consequence of which, vegetation is greatly retarded. 2. Should the summer be uncommonly wet, the succeeding winter will be very severe; because the heat or warmth of the earth will be carried off by such unusual evaporation. Farther, wet summers are mostly attended with an increased quantity of fruit on the white-thorn and dog-rose ; nay, the uncommon fruitfulness of these shrubs is considered as the presage of an intensely cold winter. - t 3. A severe winter is always indicated by the appearance of cranes and other birds of passage at an early period in autumn; because they never migrate southwards, till the cold season has commenced in the northern regions. 4. If frequent showers fall in the month of September, it seldom rains in May; and the reverse. 5. On the other hand, when the wind often blows from the south-west, during either summer or autumn; when the air is unusually cold for those seasons, both to our sensations, and by the thermometer; at the same time, the mercury being low in the barometer;-under these conditions, a profuse fall of rain may be expected. 6. Great storms, rains, or other violent commotions of the clouds, produce a kind of crisis in the atmosphere; so that they are attended with a regular succession, either of fine or of bad weather, for some months. Lastly, an unproductive year mostly succeeds a rainy winter; as a rough and cold autumn prognosticates a severe winter. See also the article BAROMETER. WEATHER is also applied to every thing lying to windward of a particular situation: hence a ship is said to have the weather-gage of another, when she is further to windward. Thus also, when a ship under sail presents either of her sides to the wind, it is then called the weather-side, and all the rigging, &c. situated thereon are distinguished by the same epithet, as, the weather shrouds, weather lifts, weather braces, weather bow, weather quarter, &c. Table of the Weather, from Dr. Herschell's Observations.— The following table is from observations taken by the late Dr. Herschell, concerning the weather. Tjiric of New or Full Moon, Weather likely to follow during the Quarter. or of entering the First Quarter. In Summer. In Winter. 12 Noon, to 2 P.M. Very Rainy, . . . . . . . . . Snow or Rain. 2 P.3I. to 4 — * - Changeable, . . . . . . . . Fair and Mild. 4 — to 6 — Fair,. . . . . . . . . . . . . . Fair. Fair, Frosty if 6 — to l l 0 — ; Fair, if Wind N.W... Wind N. or N.E. Y Rain, if Wind S or S.W. ) Rain or Snow, if - Wind S. or S.W. 10 — to 12 Midnight, Fair, . . . . . . . . * tº e º 'º gº Fair and Frosty. 12 Midnight, to 2 A.M. | Fair, .............. }º 2 A.M. to 4 — Cold, with Showers, ... Snow and Stormy. 4 - — to (; —— Rain, . . . . . . . . . . . . . . Snow and Stormy. 6 — 10 | 8 — Wind and Rain, ..... Stormy. - Cold, Rain if wind 8 — to 10 — Changeable, . . . . . . .”. } W., Snow if E. i0 — to 12 Noon, Frequent Showers, .. } Cold, with high Winds. WEATHER Beaten, an epithet applied to any thing which appears to have borne much hard or rough weather. WEATHER Bit, a turn of the cable about the end of the wind- lass, outside of the knight-heads. It is used to check the cable, in order to slacken it gradually in tempestuous weather, or when the ship rides in a strong current. WEATHER Boards, are pieces of plank placed in windows of a dwelling, or in the ports of a ship, when laid up in ordinary; they are in an inclined position, so as to turn off the rain with- out preventing the circulation of air. 1 10. Composition for Preserving Weather Boarding.—Take three parts of air-slacked lime, two of wood ashes, and one of fine sand, or sea-coal ashes. Sift these through a fine sieve, and add as much linseed oil as will bring it to a consistence for working with a painter's brush; great. care must be taken to mix it perfectly. Two coats are necessary, the first rather thin, the second as thick as can conveniently be worked. WEATHER Cloths, long pieces of canvass or tarpauling, used to preserve the hammocks from injury by weather when stowed; also to defend persons from the wind and spray. * WEATHER Helm, a ship is said to carry a weather helm when she is inclined to come too near the wind, and therefore requires the helm to be kept constantly a little to windward. WEATHER Rolls, those inclinations which a ship makes to wind ward in a heavy sea; those which she makes to leeward being termed lee-lurches. WEATHER Glass. See BA Rom Etek and HYG Romſet ER. WEATHER Shore, the shore which lies to windward of a ship. WeATHER Tide, implies that which, by setting against a ship's lee-side, while under sail, forces her up to windward. WEATHER-GLASSES, are instruments contrived to indi- cate the state or disposition of the atmosphere, and the various altérations in the weather: such are barometers, thermometers, hygrometers, &c. - WEAVERS. The wages of journeymen weavers in London are to be settled by the lord mayor, recorder, and aldermen. Masters giving more wages than is appointed, to forfeit 50l. and journeymen demanding, or combining to demand more, to for- feit 40s. or be imprisoned three months. WEAVING. With the antiquity of weaving we are neither much acquainted, nor, however amusing such knowledge might be to the antiquarian, is this loss greatly to be regretted. That the art was bropight to considerable perfection in very early ages, is sufficiently obvious both from sacred and profane history. There seems also little doubt that it is of Asiatic origin, and has only gradually extended to the western parts of Europe. We have the authority of Julius Caesar, that, when he invaded Britain, it was totally unknown ; and the many public acts relative to the woollen manufacture in the earlier period of English history, evidently prove that the greater part of our wool was, for a long series of years, exported in a raw state, and manufactured upon the continent. The cruelties and atrocities of the Duke of Alva, in 1567, and the subsequent persecutions attendant on the revocation of the edict of Nantz by Louis XIV. are assigned by historians as the causes which gave to Britain the knowledge and ingenuity of foreign artisans, and permanently founded the woollen and linen manufactures, the former of which has become the acknowledged staple of England, and the latter of Ireland. The much more recent invention of Sir Richard Arkwright has introduced the very extensive manufacture of cotton, and added a lucrative and elegant branch of traffic, the lighter and fanciful department of which has become, in some measure, the staple manufacture of Scotland; whilst the more substantial and durable have added to England a manufacture, inferior, in importance and extent, only to the woollen. * The process of manufacture of all these descriptions of cloth, from the raw to the finished or marketable state, may be divided into three great stages of manufacture. 1st. The preparatory processes which the raw material under- goes, to bring it into that state in which it is fit to assume the appearance of cloth, or what is generally understood by the term yarn. For the account of these operations, we must refer the reader to the respective articles Cotton, FLAX, Woo L, SILK, LOOM, &c. 2d. The operations by which the materials are brought from the state of yarn into of that of cloth, which is properly the subject of this article, but which we can here only treat in a general way; for the different kinds are so numerous and varied, that we must refer much of the peculiarities to the articles which will be found under the respective titles or names by which various kinds of cloths or stuffs are known. 3d. The processes which the cloth undergoes, after coming out of the weaver’s hands, to fit it for the market, and which we must also refer to the various articles—BLEACHING, DYE ING, PRINTING, CAL ENDERING, GLAZING, and many others. 12 H 1038 W E A W E A dictionARY of MECHANICAL scIENCE. In general, we may remark, that the great requisites in ever species of cloth, from the heaviest to the lightest fabrics, a durability, warmth, and beauty. For those kinds which com- pose the household furniture and dress of the generality of mankind, the first and second are the most essential ; and for the ornamental kinds, which furnish show and splendour to the drapery of the opulent and luxurious, the latter is almost the only quality ever required. Kendall's loom, which works exactly like the common Spital- field's loom, with the same tyings, hangings, &c. has its princi- pal action simply promoted by a single revolving bar mounted upon the top of the ordinary loom; equipped with four wipers, and two cams or snails. The two central wipers operating upon a lever, moving the batton as required; the two cams, right and left, acting alternately on a lever each, at the reverse end of which are connected two vertical rods, suspended from a bracket in front of the loom ; also the two levers being con- nected by a spiral spring, that the action of the cams at the necessary periods causes the spring to become charged, as the lever in traversing the cam meets with a sudden declension or fall, causing the spring to operate and drive the shuttle across the work. The other two wipers act upon two treadles, to make the shed or opening for the passage of the shuttle. One revolution of this bar completes two shutes, causes these cams and wipers to act uniformly with each other, performing the whole operation required in simple weaving. The way to accomplish more complex weaving, when more than two treadies are required, is by introducing a second bar, equipped with as many wipers as treadles wanted, the wipers being placed at equal distances on the circle of the bar. If four is necessary, as the principal bar making one revolution acts upon the battons twice; therefore, in order to work over the four treadles upon the second bar, the principal bar in this case must revolve twice to the secondary one, and so on to any given number of treadles. If five treadles are required, the principal bar must revolve two and a half times to the secondary bar once, and so on to any other number, the two bars being regulated by equipping each with cog-wheels for that purpose. If a greater number of treadles are required more than this, or the hand-loom is able to accomplish with ease, it only requires the aid of the jackard mounted upon the loom, simplifying the complex figured weav- ing. This loom is effective and simple: a boy of 12 years of age, with a proper fly-wheel, would find no difficulty in turning six or eight of these looms. The number of looms one weaver is capable of working must depend on two principal objects, the quality of the goods manufactured, and the quality of the material made use of, varying from two to five looms, such as persians, sarcemets, levantines, and poor satins, which, with good materials, require little attention. Rich works, with an able weaver and good materials, will be able to work two looms with an addition of some light work before mentioned. The work is, of course, better than that performed according to the old plan by hand; the machine acting more steadily, and operating with less of stickings. Previous to entering into any details of other particulars, we shall lay before our readers such general remarks as occur upon what is termed the fabric of cloth, a matter which we con- ceive to be not only of the most essential importance, but which has been most unaccountably neglected, even by those who practise the manufacture, and who, with very few exceptions, regulate their operations in this respect by no fixed or deter- minate rule, but generally are contented merely to copy what they are taught, without any other guide to detect error than natural experience, which very frequently is dearly purchased. Yet we conceive it very possible, that this important point may be reduced to such a degree of mathematical precision, as might render it capable of conclusive demonstration, or at least that the approximation may be so near, as to guard the person who will be at pains to adopt it, from almost the slightest danger of great error, even in regulating the fabric of any Species of cloth to which he has not been previously accus- tomed. For the better understanding of this method, it may be necessary to consider, very briefly, that quality of yarn which is called its grist or fineness. - If a thread of yarn be considered as a cylinder, its weight must be in the compound ratio of its magnitude and density. Now, yarn being made up in hanks of a determinate length, this length may be considered as the altitude of the cylinder. If cylinders are in proportion to their circumscribing squares, the square root of the square will be equal to the diameter of the base. When yarn of any kind is warped, and stretched in a loom, to undergo the subsequent operation of being woven into cloth, the threads which compose the warp are parallel to each other, and their parallel situation is preserved by the utensil called the reed, through the intervals between the divi- sions of which a certain number of threads pass. The number of divisions in this reed, therefore, ascertains the number of threads of a warp which are to be woven into cloth of any determinate breadth. Now the breadth of every thread or cylinder being the diameter of its base, and the reed being the scale which regulates the number of these threads in a given mea- sure, the ratio which the one bears to the other ascertains the number of threads, and their contiguity to each other in the cloth. Let then the square root of the mass in any determinate length of yarn be taken as the measure of the diameter of the base of a thread, and let the number of the reed which will form a proper fabric, be known, and any other will be found to form a similar fabric. From this arises a very simple analogy or pro- portion, which may be thus stated :-Let the weight of one kind of yarn be expressed by a, and that of another by b. Let a be properly woven in a reed or scale which contains 1200 intervals or divisions in 37 inches, which is the common mea- sure of the linen reed. Then to ascertain the proper reed for b, the proportion will be as Va is to 1200, so is V b to the reed required. Hence, as a is to 144, so is b to the square of the reed required. Suppose now, that a represents cotton yarn No. 60, and b represents No. 100, then, aS 60 144 : : 100 : 14,400, the root being 15:49 nearly, which is the answer. From this the following simple arithmetical proportion will arise for prac- tieal use. 1st. If the yarn is known, and the number of the reed wanted, As the name or designation of the first yarn given To the square of the given reed. So is the name or designation of the second yarn To the square of the reed required. - 2d. If, as before, the yarn and reed are known, and the yarn wanted to fit any other reed. As the square of the given reed, To the yarn, So is the square of the other reed To the yarn required. In actual practice, the following objection, which is very plausible, will readily occur to practical manufacturers, and, at first sight, will probably induce almost the whole of them to reject these rules as erroneous and inconclusive. They will assert, and with truth, that a manufacturer who would impli- citly adopt and follow these rules, would either make all his fine goods so dense and heavy in the fabric as to disgust his customers; or that his coarse goods would be so flimsy in the texture as to be totally useless. To this it is only necessary to reply, that it arises from no error in the calculation, nor want of truth in the general principle, but in what was premised as a general requisite in cloth at the outset, namely, that the dura- bility and thickness is the first object in coarse goods, and beauty and transparency in fine. It would afford but a slender recommendation to a birth-day dress, to possess that warmth and durability which would form the chief excellence of a watch- coat or blanket; and it would be equally useless to give to the coarse manufacture, which is valuable in proportion to the shelter which it affords from the inclemency of wind and wea- ther, qualities which could only aſford gratification to the eye, by the sacrifice of every comfort. The warp of a web being longitudinally stretched in parallel straight lines, and the warp or weft being inserted at right angles to it, the substance produced as cloth will bear a strong analogy to the form of a raft of wood, consisting of two plat- forms of square beams laid across each other, and fastened together; or if we suppose, that a number of cylindrical pieces of wood, such as the top masts or yards, of a ship, are laid parallel to each other, and that cords or ropes are interwoven between them together, we shall have a very exact representa- r (TILOTEL VLANUIFACTURE , Prux cut-LE or TExTºurE. O-EN E-A-RIC . C Los - FABRL- Fºy-1. Piº 3. OPEN FABRLC. directiºn-ºn-of-arranea- Coxixºtox Fabric. Fº - Do UBLE or CARPET FABR1c. */- 2. - - - - Zºº. 6. º - -º-º-º- - Twº ELIED FABRIC . VELVET EABRIC . DDMITY, DLAPER. KERs by MERE. - Zºº. 9. coeeeeeeeººººoººººee … 2 3 - º Dobºnocrº & Diape B . Cord Du Roi . Fig. 75. C. OMMON GAUZE . D.A.Masrº & TAPE sºr Bay. Aºzz. zo. C.A.T GUIT. Fiv. 12. ºw HI-P ºn ET . Bob DERs, stºulºs, & Spot TING . Fºy, 27. MALL INET . Fig.14. º -- yº- Cºlon London 1825 w"E A W. E. A 1039 DICTIONARY OF MECHANICAL scIENCE. tion of a piece of cloth on a scale of such magnitude as will admit of all the proof of actual measurement. In cloth, even of the finest kinds, the length, breadth, and number of the com- | ponent thread of cylinders, in the piece, may be ascertained with equal precision; but from the smallness of the diameter of every thread, it becomes impossible to measure them actually with any degree of accuracy. The length and the weight, or mass, however, being known, the diameter may be found by a calculation, which bears evident marks of great exactness, and we may then safely assume that no difference can arise, pro- vided the densities of all threads are the same. Upon this point, however, there has been some difference of opinion, and the subject has been so little investigated in a scientific man- ner, that it would be perhaps presumptuous to draw any abso- lute conclusion upon it. the argument upon which the increase of density in fine yarn above coarse chiefly rests, is this, that in spinning fine yarn, a greater number of revolutions of the wheel are necessary to give the twist sufficiently to produce a proper cohesion of the fibres than in coarse. This is incontrovertibly true ; and as the filaments or fibres, by this twisting, assume the form of a screw or spiral, the point to be decided is, simply, whether by this excess of twisting, the fibres of fine yarn are not brought more closely into contact than those of coarse; and consequently, that the diameter of the thread is diminished in the same pro- portion that the twisting is increased. It must be obvious, that where the circumference exposes a small surface, many more revolutions will be required than where it presents a large one, before all the fibres can be suffi- ciently stretched; and consequently, that fine yarn will always require more twisting than coarse, to give it the same tenacity. But as every thread, from the stoutest cable to the finest which human art and industry can produce, contracts in length by the operation of twisting, there seems reason enough to con- clude, that the compressing power exerted, acts either entirely upon the length, or that what is exerted on the diameter, must bear a very small proportion indeed to the other; we may therefore infer, that the nearest approximation to actual truth, will be to consider a rope or thread like any other solid cylin- der, and that the difference of density will not very materially affect the calculation. Upon this principle, we shall easily arrive at a very considerable degree of mathematical precision, and, upon the whole, come nearer to actual truth than by any other hypothesis yet known. In the Plate (CLoth MANUFACTURE) will be found some figures, explanatory of what further remarks may be necessary on this subject, as connected with the fabric; and it will also be useful in conveying correct ideas of the varieties of texture most generally used both in the substantial and flimsy descrip- tions of woven goods. - Principle of Texture.—Figure 1. This figure may be sup- posed to represent any solid body composed of various parts, lashed together. If the darkened squares are so many parallel beams of wood, connected by cordage, we arrive at once at a precise idea of texture. The length of these beams is known by measurement: the breadth of the whole consists of the aggregate number of pieces of wood, added to the space which the cords occupy between each, and which will be more or less in proportion to the thickness or diameter of these cords. It is also obvious, that it is impossible to bring the beams into actual contact; for were we to suppose, that the connecting or lashing cords were actually as fine as human hairs, they must still occupy some portion of space. The thickness, it is equally apparent, is that of one beam and one cord ; but if we suppose the cords every where in actual contact, we may then also sup- pose that the thickness is that of the beam and two cords. Now, it is hardly possible to conceive, that in a flexible sub- stance, such as those used in the fabrication of cloth, any means could be devised to bring every thread of woof into actual con- tact, so as to cover the warp both above and below. We may therefore very safely assume, as a general principle, that the geometrical thickness of cloth is the measure of the diameter of one thread of the warp, added to the measure of the diameter of one thread of the woof; and that when those measures are equal, the thickness of the cloth is, of course, double the diame- ter of one of the threads of which it is composed. Thus we have We shall therefore only observe, that the utmost thickness of fabric of which cloth is capable, and more than even the strongest canvass, with which we are acquainted, can possess. Indeed a fabric of this kind, were it even easily attainable, would be practically useless; for the immense increase of density would so completely take away every degree of pliancy and flexibility, that the fabric would be . as unsuitable for any purpose to which cloth is properly appli- cable, as a fir plank or a sheet of copper. Open Fabric.—Figure 2. This figure represents a section of cloth of an open fabric, when the round dots, which represent the warp, are placed at a considerable distance from each other. In this figure we see very evidently, that the geome- trical thickness of cloth may be considered in the duplicate ratio of the one thread ; for if we suppose the two parallel lines which bound the figure, to represent two boards used in the calender press, where the cloth is finished, and that they are to be pressed together by any mechanical power, we shall at once see that their effect must immediately flatten the threads, and divest them of their cylindrical form. Close Fabric.—Figure 3. This figure represents a plain fabric of that description which approaches the most nearly to any idea we can form of the most dense or close contact of which yarn can be made susceptible. Here the warp is supposed to be so lightly stretched in the loom, as to retain entirely the parallel state without any curves or flexure whatever, and the whole therefore is necessarily given to the woof. This mode of weaving can never really exist; but if the warp be sufficiently strong to bear any light stretching, and the woof be spun very soft and flexible, something very near it may be produced. This way of making cloth is well fitted for those goods which require to give considerable warmth, but they are sometimes the means of very gross fraud and imposition; for if the warp is made of very slender threads, and the woof of slackly twisted cotton or woollen yarn, where the fibrils of the stuff being but slightly brought into contact, are rough and oozy, a great appearance of thickness and strength may be given to the eye, when the cloth is absolutely so flimsy, that it may be torn asunder as easily as a sheet of writing paper. Many frauds of this kind are practised. A very common one is in a kind of fanciful stuff, which used to be hawked about the streets of London, and most of the large towns of Britain, especially the sea ports, by a set of men habited like sailors. These stuffs were composed of very fine silk warp, and very slackly twisted cotton woof, perhaps eight or ten times coarser than the warp. The silk, of course, entirely disappeared, and the semblance of a very strong fabric of cotton was presented, and sold appa- rently cheap, under the pretence of being smuggled home in an East Indiaman, Strength, beauty, and cheapness, were thus apparently united, and the unwary purchaser, whilst enjoying the triple pleasure of having profitably expended his money, procured a desirable acquisition, and outwitted all the precau- tions which either the government or directors could take, found, to his infinite astonishment and vexation, upon the first application of the finger and thumb, that his purchase, which was generally extolled by the vender for being as tough as the mainsail of a seventy-four, proved as weak as a cobweb. The impostor generally added to the fraud, by pulling the cloth apparently with great force in that direction in which the coarse woof gave the resistance, but cautiously avoided even a touch against the warp, which would at once have detected the fraud. Open Fabric.—Figure 4. This figure gives a representation of the position of a fabric of cloth in section, as it is in the loom before the warp has been closed upon the woof, which still appears as a straight line. This figure may usefully illustrate the direction and ratio of contraction which must unavoidably take place in every kind of cloth, in a greater or smaller degree, according to the density of the texture, the dimensions of the threads, and the description of the cloth. Let A B represent one thread of woof completely stretched by the velocity of the shuttle in passing between the threads of warp which are repre- sented by the round dots: 1, 2, 3, 4, 5, &c. and those distinguished by 8, 9, 10, &c. When these threads are closed by the opera- tion of the heddles to form the intertexture, the first tendency will be to move in the direction 1 b, 2 b, &c. for those above, and in that of 8 a., 9 a., &c. for those below ; but the contraction of A B, by its deviation from a straight to a curved line, in 1040 W. E. A W .E. A DICTIONARY OF MECHANICAL SCIENCE. consequence of the compression of the warp thread lb, 2b; &c. and 1 a, 2a, &c. in closing, will produce, by the action of the two powers at right angles to each other, the oblique or dia- gonal direction denoted by the lines 1,8–2,9 to the right, for the threads above; and, that expressed by the lines 2, 8–3, 9, &c. to the left, for the threads below. Now, as the whole devia- tion is produced by the flexure of the thread A B, if A is sup- | posed to be placed at the middle of the cloth, equidistant from the two extremities, or selvages as they are called by Weavers, the thread at 1 may be supposed to move really in the direction 1 b, and all the others to approach to it in the direction repre- sented, while those to the left would approach in the same ratio, but the line of approximation would be inverted. By pursuing this plan, which, as far the writer of this article knows, is totally new, the theory of fabric might be reduced to a very great degree of certainty; and here a field is entirely open for the researches of an expert geometrician to apply the principles of his science to the most extensive and useful manufacture, not only of this country, but of every other. Figure 5 represents that common fabric used for lawns, mus- lins, and the middle kind of goods, the excellence of which neither consists in the greatest strength, nor in the greatest transparency. It is entirely a medium between fig. 2 and fig. 3. Its principles are in every respect similar to those already noticed. - . In the efforts to give great strength and thickness to cloth, it will be obvious, that the common mode of weaving by constant intersection of warp and woof, although it may be perhaps the best which can be devised for the former, presents invincible obstructions to the latter beyond a certain limit. To remedy this, two modes of weaving are in common use, which, while they add to the power of compressing a great quantity of mate- rials in a small compass, possess the additional advantage of affording much facility for adding ornament to the superficies of the fabric. The first of these is double cloth, or two webs woven together, and joined by the operation. This is chiefly used for carpets; and its geometrical principles are entirely the same as that of plain cloth, supposing two webs to be sewed together. A section of the cloth will be found in fig. 6; and what further relates to this part of the subject, in the article CARPet. Of the simplest kind of twisted fabrics, a section is given in fig. 7: and as this is a most important branch of the cloth manufacture, it may be proper to consider it with some atten- tion. The great and prominent advantage of the twisted fabric in point of texture, arises from the facility with which a very great quantity of materials may be put closely together. In the figures, the warp is represented by the dots in the same straight line as in the plain fabrics; but if we consider the direction and ratio of contraction, upon principles similar to those laid down in the explanation given of fig. 4, we shall readily discover the very different way in which the tweeling fabric is effected. Thus we see by the figure, when the dotted lines are drawn at a, b, c, d, their direction of contraction, instead of being upon every second or alternate thread, the natural tendency would consequently be to bring the whole into the form repre- sented by the lines and dotted circles at a, b, c, d. In point then of thickness, from the upper to the under superficies, it is evident that the whole fabric has increased in the ratio of nearly three to one. On the other hand it will appear, that the four threads or cylinders being thus put together, in one solid mass, might be supposed only one thread, or like the strands of a rope before it is twisted; but, to remedy this, the thread being shifted every time, the whole forms a body in which much aggregate matter is compressed ; but where, being less firmly united, the accession of strength acquired by the accumulation of materials, is partially contracted by the want of equal firmness of junction. The second quality of the tweeled fabric, susceptibility of receiving ornament, arises from its capability of being inverted at pleasure, according to fig. 9. In this figure, we have, as before, four threads, and one alternately intersected ; but here the four threads marked 1 and 2, are under the woof, while those marked 3 and 4 are above. As this in no way affects the solidity or strength of the texture, but is merely an auxiliary aid for the addition of ornament, the further discussion of this property will be more appropriately introduced in that part of this article which relates to the ornamental principles of texture. . - Figure 8. This figure represents that kind of tweeled work which produces an ornamental effect, and adds even to the strength of a fabric, in so far as accumulation of matter can be considered in that light. The figure represents a piece of velvet cut in section, and of that kind which, being woven upon a tweeled ground, is known by the name of Genoa velvet; a pretty strong presumption, that the origin of this manufacture at least, in Europe, is Italian. That part, however, which pro- duces the ornament, cannot properly be deemed likely to add much to the strength of the fabric, in so far as this is effected by any attempt at divulsion; but when the impulse is by fric- tion, it must contribute very materially to its preservation. Hence, in practical use, velvets of every kind are in great estimation, for three substantial reasons:— 1st. Because, by combining a great quantity of materials in a small compass, they aſford great warmth. 2nd. From the great resistance which they oppose to external friction, they are very durable. And, 3rd. Because, from the very nature of the texture, they afford the finest means of rich ornamental decoration. The use of velvet cloths in cold weather, is a suffi- cient proof of the truth of the first. The manufacture of plush corduroy, and other stuffs, for the dress of those exposed to the accidents of laborious employment, evinces the second; and the ornamented velvets and Wilton carpeting, are demonstrative of the third of these positions. In the figure, the diagonal form which both the warp and woof of cloth assume, is very apparent, from the smallness of the scale. Besides what this adds to the strength of the cloth, the plushed part, which appears interwoven at the darkly shaded intervals 1, 2, 3, &c. forms, when finished, the whole covering or upper surface. The principle, in so far as regards texture, is entirely the same as any other tweeled fabric, and a more minute discussion must be referred to the particular article. e Corduroy.—Figure 10. This figure, which represents cordu- roy, or king’s cord, is merely striped velvet. The principle is entirely the same; and the figure itself will sufficiently evince that the one is merely the copy of the other. The remaining figures in the plate represent those kinds of work which are of the most flimsy and open description of texture; those in which neither strength, warmth, nor durability, is much required, and of which openness and transparency are the chief recommenda- tions. For these reasons, the nature and principle of the texture may be better understood by considering them as mere superficies, than by any section which could be exhibited. The two kinds of gauze and catgut, which form the basis of all the varieties, are still exhibited in section, and the two others, which may be varied almost to infinity, are shewn superficially. Common Gauze.—Figure 11. This figure represents common gauze, or linau, a substance used for various purposes. The essential difference between this description of cloth and all others, consists in the warp being twined or twisted like a rope during the operation of weaving; and hence it bears a considerable analogy to the substance usually known by the name of lace. The twining of gauze is always open, flimsy, and transparent : but, from the twining of the warp, it possesses an uncommon degree of strength and tenacity, in proportion to the quantity of materials which it contains. This quality, toge- ther with the transparency of the fabric, renders it peculiarly adapted for ornamental purposes of various kinds, particularly for ſlowering or figuring, either in the loom, or by the needle. . In the warp of gauze there arises a much greater degree of contraction during the weaving than in any other species of cloth, and this is produced by the twining. The geometrical ratio of this contraction must evidently depend entirely upon the same principle which regulates the contraction of the yarn in spinning, and therefore it is unnecessary to add to what has been already stated upon that subject. By inspecting the figure, it will be apparent, that the twisting between every intersection of woof amounts precisely to one complete revolu- tion of both threads; hence the following difference between this and every other species of weaving, namely, that the same W .E. A. DIC'ſ"IONARY OF W E I 1041 MECHANICAL SCIENCE. thread of warp is always above the woof, and the contiguous thread is always below. Catgut.—Figure 12. This figure represents a section of another species of twisted cloth, which is known by the name of catgut, and which differs only from the gauze, by being sub- jected to a greater degree of twine in weaving, for in place of one revolution between each intersection, a revolution and a half is always given; and thus the warp is alternately above and below, as in other kinds of weaving. The ratio of contrac- tion in this, as in the former, is evidently reducible to the same principles which regulate the spinning. - Whip Net.—Figure 13. This figure is a superficial represen- tation of the most simple kind of ornamental net-work pro- duced in the loom. It is called a whip-met by weavers, who use the term whip for any substance interwoven in cloth for ornamental purposes, when it is distinct from, the ground of the fabric. In this, the difference is merely in the crossing of the warp ; for it is very evident, that the crossings at 1, 2, 3, 4, and 5, are of different threads from those at 6, 7, 8, and 9. The contraction in weaving this kind of stuff, is vastly greater than any other, and may very easily be ascertained with the utmost geometrical precision, depending entirely on the well-understood principles of plain trigonometry; for it will hardly be necessary to take into the account what contraction takes place by the crossing of the threads in a fabric so very open and flimsy. Thus, if the diamond is crossed at 1 by a dotted line, four right-angled triangles will be formed, and the contraction of the warp will be in the ratio which the hypothen use of each bears to the perpendicular; the former being the longitudinal mea- sure of the warp when stretched in the loom, and the latter that of the cloth in its finished state. This reduces the con- traction at once to the Pythagorean proposition, that the two are to each other in the ratio of their respective squares. Mail Net.—Figure 14. This figure represents, superficially, what is called the mail-net, and is merely a combination of common gauze and the whip-net in the same fabric ; the gauze here being in the same direction as the dotted line in the former figure. The whole fabric is evidently a continued suc- cession of right-angled triangles, of which the woof forms the bases, the gauze part the perpendiculars, and the whip part the hypothen uses ; the contraction here being very different, it is necessary that the gauze and whip parts should be stretched upon separate beams. - The above may be regarded rather as hints for the further investigation of the geometrical principles of the cloth manu- facture, than as the absolute results of a perfect and matured theory. As nothing has been published upon the subject, the author of this article can only plead its obvious importance, as the motive which has led him to communicate what has occurred to him as likely to promote a more ample and scientific inquiry. We now proceed to state what occurs upon the ornamental principles of texture, referring the reader to figs. 15, 16, and 17. In order to produce ornamental figures upon cloths, it is necessary that the apparatus, or mounting of the loom, should be properly arranged for the purpose intended, previously to the commencement of the subsequent operations. The rules for this are pretty similar in all the different kinds of ornamen- tal work, and the plans being previously drawn upon design paper, the first operation is to adapt the loom to the design. The designs, or patterns, are included between a certain num- ber of parallel straight lines drawn upon the paper, and inter- sected by others drawn at right angles to the first. The lines which are drawn from the top to the bottom of the paper may be supposed to represent the warp, and those drawn across, the woof of the web; any number of threads being supposed to be included between every two lines. The paper thus forms a double scale, by which, in the first instance, the size and form of the pattern may be determined with great pre- cision ; and the whole subsequent operations of the weaver, both in mounting and working his loom, regulated with cer- tainty and accuracy. To enable the projector of a new pattern to judge properly of its effects when transferred from the paper to the cloth, it will be essentially necessary that he should bear constantly in his view the comparative scale of magnitude which the design will bear in each, regulating his ideas always by square or superficial measurement. 110. w Thus in the large design, fig. 16, representing a bird perched upon the branch of a tree, it will be proper, in the first place, to count the number of spaces from the point of the bill to the extremity of the tail; and to render this the more easy, it is to be observed, that every tenth line is drawn considerably bolder than the others. This number in the design is 135 spaces. Counting again from the stem of the branch to the upper part of the bird’s head, he will find 76 spaces. Between these spaces, therefore, the whole superficial measure of the pattern is contained. By the measure of the paper, this may be easily tried with a pair of compasses, and will be found to be nearly 6% inches in length, by 35, inches in breadth. Now, if this is to be woven in a reed containing 800 intervals in 37 inches, and if every interval contains five threads, sup- posed to be contained between every two parallel lines, the length will be 6'24 inches, and the breadth 3:52 inches nearly, so that the figure upon the cloth would be very nearly of the same dimensions as that upon the paper; but if a 1200 reed were used instead of an 800, the dimensions would be propor- tionally contracted. A correct idea being formed of the design, the weaver may proceed to mount his loom according to the pattern, and this is done by two persons, one of whom takes from the design the instructions necessary for the other to follow in tying his cords. It remains only for us now to take notice, very shortly, of figs. 15, 16, and 17. Dornock and Diaper.—Figures 15, 15. This figure is a represen- tation of the most simple species of table linen, which is merely an imitation of checker work of various sizes, and is known in Scotland, where the manufacture is chiefly practised, by the name of Dornock. When a pattern is formed upon tweeled cloth, by reversing the flushing, as formerly explained, the two sides of the fabric being dissimilar, one may be supposed to be represented by the black marks, and the other by the part of the plate which is left uncoloured. For such a pattern as this it is perfectly unnecessary to have recourse to the draw loom, for two sets of common tweel heddles, moved in the ordinary way, by a double succession of heddles, are quite sufficient. The other part of fig. 15 is a design of that intermediate kind of ornamental work which is called diaper, and which partakes partly of the nature of the Dornock, and partly of that of the damask and tapestry. The principle upon which all these species of goods are woven is entirely the same, and the only difference is in the extent of the design, and the means by which it is executed. The last figure, 17, is a design for a border of a handkerchief or napkin, which may be executed either in the manner of damask, or as the spotting is practised in the lighter fabrics. WEAVING-LOOM. See LOOM. WEB, a tissue or texture formed of threads interwoven with each other; some whereof are extended in length, and called the warp; and others drawn across, and called the woof. WEDGE, one of the five mechanical powers, or simple. engines, being a geometrical wedge, or very acute triangular prism, applied to the splitting of wood, rocks, or raising great weights. See MechA NICs. - WEIGH, WAY, or Wey, (waga,) a weight of cheese, wool, &c. containing 256 pounds avoirdupois. Of corn, the weight con- tains forty bushels; of barley or malt, six quarters. In some places, as Essex, the weight of cheese is 300 pounds. WEIGHING-ENGINES, are often constructed in order to ascertain the weight of the loads on waggons and carts passing along turnpike roads. To prevent the roads from being too much worn, it has been found expedient to fix by an act of parliament a certain load for each breadth of wheel ; and, that such loads may not be exceeded, there are weighing machines at several of the toll-gates, by which the loads of the several waggons, &c. passing through them can be determined. In some of these machines the contrivance is such, that the carriage whose load is to be weighed is lifted clear from the ground, by means of four strong chains and hooks attached to a large steel-yard, whose fulcrum is raised commonly by a combination of tooth and pinion-work, moved by a winch handle; but it is far better to have the business performed by means of apparatus placed under a horizontal frame on which the carriage may be drawn. The most compendious and economical machine of this kind that we have seen, is one, first used for weighing the riders of 12 I 1042 W E I W E L DICTIONARY OF MECHANICAL SCIENCE. race horses, and afterwards applied to the more reputable ser- vice of weighing loaded carriages. The annexed figure is a plan of the machine ; KL M N is the plan of a rectangular box, which has a platform lid or cover of size sufficient for placing the wheels of a cart or waggon. The box is about a foot deep, and is sunk into the ground till the platform cover is even with the surface. . In the mid- dle of the box is an iron lever supported on the fulcrum pin i k, formed like the nail of a balance, which rests with its edge on arches of hardened steel firmly fastened to the ‘bottom of the box. This lever goes through one side of the box, and is fur- nished at its extremity with a hard steel pin l m, also formed to an edge below. In the very middle of the box it is crossed by a third nail of hardened steel g h, also formed to an edge, but on the upper side. The three edges are in one horizontal plane, as in a well-made balance. In the four corners, A., A', E, E, of the box are firmly fixed four blocks of tempered steel, having their upper surfaces formed into spherical cavities, well polished and hard tempered. A B C D E represents the upper edge of an iron bar of considerable strength, which rests on the cavities of the steel-blocks in A and E, by means of two hard steel studs projecting from its under edge, and formed into- obtuse-angled points or cones. These points are in a straight line parallel to the side KN of the box. The middle part C of this crooked bar is faced with hard tempered steel below, and is there formed into an edge parallel to A E and KN, by which it rests on the upper edge of the steel ping h, which is in the lever. In a line parallel to A E, and on the upper side of the crooked bar A C E, are fixed two studs or points of hardened steel B and D projecting upwards above half an inch. The platform cover has four short feet like a stool terminated by hard steel studs, which are shaped into spherical cavities and well polished. With these it rests on the four steel points B, B' D', D. The bar A C E, is kneed in such a manner vertically, that the points A, B, D, E, and the edge C, are all in a hori- zontal plane. looking at the elevation in fig. 6. bar A C E must be understood as also said of the bar A'C' E'. Draw through the centre of the box the line a b c perpendi- cular to the line A E, BD. It is evident that the bar A C E is equivalent to the lever a b c, having the fulcrum or axis A. E. resting with its extremity C on the pin h g, and loaded at b. It is also evident that a c is to a b as the load on this lever to the pressure which it exerts on the pin gh, and that the same pro- portion subsists between the whole load on the platform, and the pressure which it exerts on the ping h. It will also appear on an attentive consideration, that this proportion is no wise. deranged in whatever manner the load is placed on the plat- form. If very unequably, the two ends of the pin gh, may be unequally pressed, and the lever wrenched and strained a little; but the total pressure is not changed. If there be now placed a balance or steel yard L. K., in such a manner that one end of it may be directly above the pin lm in the end of the lever E OF they may be connected by a wire or slender rod, and a weight | on the other arm of the balance or steel-yard may be put in These particulars will be better understood by What has been said of the equilibrio with any load that can be laid on the platform. A. small counterpoise being first hung on to balance the apparatus when unloaded, any additional weight will measure the load really laid on the platform. If a b be to a c as 1 to 8, and E O to EF also as 1 to 8, and if a common balance be used above, 64 pounds on the platform will be balanced by one pound in the scale, and every pound will be balanced by one-fourth of an ounce. This would be a very convenient partition for most purposes, as it would enable us to use a common balance and common weights to complete the machine; or it may be made with a balance of unequal arms, or with a steel yard. Some have thought to improve this instrument by using edges like those of the nails of a balance instead of points. But unless made with uncommon accuracy, they will render the balance very dull. The small deviation of the two edges A and E, or of B and D, from perfect parallelism to KN, is equivalent to a broad surface equal to the whole deviation. We imagine, that with no extraordinary care, the machine may be made to weigh within gº of the truth, which is exact enough for any purpose I O CO HYi II). CI”(; 6. It is necessary that the points be attached to the bars. Some have put the points at A and E in the blocks of steel fastened to the bottom, because the cavity there lodged water or dirt, which soon destroyed the instrument with rust. But this coca. sions a change of proportion in the first lever by any shifting of the crooked bars: and this will frequently happen when the wheels of a loaded cart are pushed on the platform. The cavity in the steel stud should have a little rim round it, and it should be kept full of oil. In a nice machine a quarter of an inch of quicksilver would effectually prevent all these inconveniences. The simplest and most economical form of this machine is to have no balance or second steel-yard ; but to make the first steel-yard E O F a lever of the first kind, viz. having the fulcrum between O and F, and allow it to project far beyond the box. The long or outward arm of this lever is then divided into a scale of weights commencing at the side of the box. A counter- poise must be chosen, such as will, when at the beginning of the scale, balance the smallest load that will probably be ex- amined. It will be convenient to carry on this scale by means of eke-weights hung on at the extremity of the lever, and to use but one moveable weight. By this method the divisions of the scale will have always one value. The best arrangement is as follows: place the mark 0 at the beginning of the scale, and let it extend only to 100, if for pounds, or to 112 if for cwts. ; or to 10 if for stones; and let the eke-weights be numbered 1, 2, 3, &c. Let the lowest weight be marked on the beam. This is always to be added to the weight shewn by the operation. Let the eke-weights stand at the end of the beam, and let the general counterpoise always hang at 0. When the cart is put on the platform, the end of the beam tilts up. Hang on the . heaviest eke-weight that is not sufficient to press it down. Now complete the balance by sliding out the counterpoise. Suppose the constant load to be 312 lbs. that the counterpoise stands at 86, and that the eke-weight is 9; we have the load=986 + 312. = 1298 lbs. WEIGHT, gravity, in Physics, a quality in natural bodies, whereby they tend downwards towards the centre of the earth. Weig Ht, pondus, in Mechanics, is any thing to be raised, sustained, or moved by a machine, any thing that in any man- ner resists the motion to be produced. Weight, in Commerce, denotes a body of a known weight, appointed to be put in the balance against other bodies, whose weight is required. . Weights, Modern, English. See Me Asures. - Wei G HTs, and Measures. The standard of measures were originally kept at Winchester, which measure was, by the law of king Edgar, ordained to be observed through the kingdom. WELD, or WoALD, (resede luteola, Linn.) is a plant cultivated in Kent, Herefordshire, and many other parts of this kingdom. The whole of the plant is used for dyeing yellow ; though some assert that the seeds only afford the colouring matter. Two sorts of weld are distinguished : the bastard or wild, which grows naturally in the fields; and the cultivated, the stalks of which are smaller, and not so high. For dyeing, the latter is preferred, it abounding more in colouring matter. The more slender the stalk, the more it is valued. When the weld is ripe ** - º º in - ** ** *** ** º - D ºne - * º zºº º C-T- I | - | | | , - . *º-º. - * * * * * * * * /ø///º/1///, /º/ º: º a º /. - -ºº: - W H E W H F. DICTIONARY OF MECH AN ICAL SCIENCE. 1043 it is pulled, dried, and made into bundles, in which state it is used. The yellow communicated to wool, by weld, has little permanency, if the wool be not previously prepared by some mordant. For this purpose alum and tartar are used, by means of which this plant gives a very pure yellow, which has the advantage of being permanent. w WELDING. Welding is that intimate union produced between the surfaces of two malleable metals, when heated almost to fusion, and hammered. This union is so strong, that when two bars of metal are properly welded, the place of junc- tion is as strong, relatively to its thickness, as any other part of the bar. Only two of the old metals are capable of firm union by welding, namely platina and iron; the same property belongs to the newly discovered metals, potassium and sodium. WELDING HEAT, in Smithery, a degree of heat given to iron, &c. sufficient to make any two bars or pieces of iron unite by a few strokes of the hammer, and form one piece. WELL, in naval affairs, an apartment formed in the middle of a ship’s hold, to enclose the pumps from the bottom to the Iower deck. Its use is to defend the pumps from damage, and prevent the entrance of ballast, &c. which would otherwise choke the tubes in a short time, and render the pumps incapable of service. By means of this enclosure, the artificers may like- wise more readily descend into the hold, to examine or repair the pumps as occasion requires. Well, of a Fishing Vessel, an apartment in the middle of the hold, which is entirely detached from the rest, being lined with Head on every side, and having the bottom thereof perforated with a number of small holes, through the floor, so that the water passing into the well is always as fresh as that in the sea, and is nevertheless prevented from communicating with other parts of the hold. Its use is to preserve the fish alive which are put into it. Well-Room of a Boat, the place in the bottom where the water lies between the ceiling and the platform of the stern sheets, from whence it is thrown out into the sea with a scoop. WERST, or VeRst, a Russian linear measure, equal to 3500 English feet. l WHALE. BALAENA. WHARF, a perpendicular building of wood or stone raised on the shore of a road or harbour, for the convenience of loading or discharging a vessel by means of cranes, tackles, capstans, &c. A wharf is built stronger or slighter in proportion to the effort of the tide or sea which it is to resist, and to the weight which it is intended to support. WHARFINGER, the person who has the charge of a wharf, and takes account of all the articles landed thereon, or removed from it, for which he receives a certain fee called wharfage, as a due to the proprietor for the rent of the quay or wharf, and for the use of his machines and furniture. WHEAT. See TRITICUM and HUSBAN DRY. W Heat-EAR. See Mot Aci Li A. WHEEL, in Mechanics, a simple machine consisting of a round piece of wood, metal, or other matter, which revolves on an axis. The wheel is one of the principal mechanic powers; it has place in most engines; in effect, it is of an assemblage of wheels that most of our engines are composed. See MechA- Nics and MILL. We shall here introduce to the reader's notice a substitute for wheels, denominated Scapers, the ingenious invention of L. Gompertz, Esq., on the accuracy of which the utmost reliance may be placed, it having been derived from the most unquestionable authority, accompanied with a beautifully en- graved plate of the diagrams by Lowry:— * WHEELS, Substitutes for, termed SCAPERs, are certain pieces of mechanism, for which a patent has been granted to Mr. Lewis Gompertz, intended generally to supersede wheels for carriages, which, while they support the carriage without rising and falling, also escape the chief obstacles and friction of the ground, produced by the asperities or softness of its surface, by which means a much lighter draught, and a more equable motion, is obtained, and the destruction of the gravel in the road prevented. Our limits not allowing a full detail of the numerous modifi- cations of this machine, we refer our readers, first, to the Repertory of Arts, second series, No. cliv. vol. 26; secondly, raising or sinking the carriage. to vol. 39, number for June 1821 ; and thirdly, to the inventor’s work, “Moral Inquiries;” where there are several varieties of scapers explained, some of which form a sort of rail-way for themselves as they go, while others act without a rail-way, and go with still less friction. Part of the advantages promised by this invention may readily be conceived, when it is considered how many horses a common road requires, for one on a rail-way. The action of carriage wheels is observed by the inventor as not being generally well understood. (See his observations in No. CLXIX. vol. 29, Repertory.) He also considers the opposition presented to wheel carriages, even on a smooth surface, to be much greater than is generally believed ; and, in support of these ideas, adds the testimony of the late learned M. Charles Bossut, who, in his “Cours de Mathématique, tome troisieme,” treats of two sorts of friction; one of “bodies qui glissent,” (which slide,) and the other of bodies “qui tournent,” (which turn, without alluding to the axle,) and where M. Bossut fur- ther observes, that “the existence of the latter species of friction has been overlooked by those who were, in other respects, good mechanics.” The inventor has completed several small and large models of these scapers, which he found to work well; though he is, we believe, still engaged in further improvements upon them. We shall omit the first plans in the Repertory, vol. 26, and proceed, first, to those vol. 39; and secondly, to those in “Moral Inquiries.” t Figs. 3 and 4 shew the simplest, though not tile best species of scapers. a, a, a, a, is the frame of a carriage, with two of these scapers in different positions; A B C D are two crosses, strengthened, if necessary, with pieces, b, c, d, e. The ends or feet, f, g, h, i, of the crosses being circular, as shewn, and these should be six inches wide, or more. These crosses move along the road by bearing on each foot alternately, and though they have themselves the evil of rising and falling in their centres of gravity, they do not allow the carriage to be thus affected : the operation is as follows;–Fig. 19 is a double axle, parallel and in opposite directions to each other, whose parallel dis- tance from centre to centre is exactly half of what the centre of the cross rises and falls. The longest axle Q works in a box or tube in the carriage, and axle P in a box in the cross, and they make a whole revolution at every change of foot, so that when the leg which is on the ground is perpendicular to the ground, axle P is full upwards; and when two feet touch level ground at once, the axle P is quite downwards; the centres, then, of the cross, consequently, will move in a circle whose diameter, is the whole distance of the rise and fall, by which means the cross will be prevented, though it rises and falls itself, from communicating that motion to the carriage. The motion this crank allows to the centre, effects two objects: first, it gives the rise and fall; and secondly, it causes the scaper to surmount those obstacles gradually upon which the feet happen to alight, contrary to what would take place if the centre moved up and down in a right line. The motion of the cross is then guided by four wheels E, F, G, H, one situate on each leg, as shewn, which continually bearing against a properly curved iron or sweep, I J K L M, affixed to the carriage, produces the effect required, and which would, if not for side pressure, guide the motion without the crank. A superior sort of scaper is shewn in figs. 1 and 2, in two positions, each of which consists of a parallelogram. A, B, w, w, CD and y V, moveably jointed at y, V, u, w; E G H F are two cross pieces jointed to the middle of each of the former pieces, A B, C D w u, and y ; V the centre of the cross pieces E G H F have a box for an axle to go through, and one of these boxes fits into the other; this axle being fixed in the carriage, and on which the parallelogram is placed as a common wheel. These eight joints allow this frame to open and shut, and constitute the chief of the scaper, turning round as it goes, and con- tinually opening and shutting; by which means it runs without A B C D are four feet, each consisting of a quarter of a circle, or a very little more, described from the joints to which they belong ; and in fig. 1, from the Rolling Angle, (see the sequel); so that some part of the foot is always perpendicularly under the joint. Two of these feet are formed on one side T G C, and two on the oppo- site side A E B ; the two other sides being without any. This 1044. W H E W H E IDICTIONARY OF MECHANICAL SCIENCE. frame then being a parallelogram, and the centre being fixed, the two joints which are diagonally opposite, will, in all their motions, be similar; therefore, if a straight guide were affixed to the carriage near the top of the parallelogram, and four small rollers were attached to the joints V w, w, y, so that they bore on the top of this straight piece, then would the scaper be pro- perly guided when on level ground. And if another straight piece were placed above this, forming a groove with the lower piece, the little wheels would bear upwards against it when the feet came upon an elevation or depression of ground, and it would for a time guide the motion instead of the lower piece. Or these straight guides might be fixed below, so as to conduct the wheels in the lower part of their circuit. But the following and better way of guiding has been adopted by the inventor in his models, as possessing less friction :- It is to be observed, that when the top and bottom joints V and w, fig. 2, describe right lines on the carriage, as it moves along, the intermediate joints w and v, describe curves relative to the carriage, very nearly resembling parts of circles (on both sides) drawn through the three centres of the joints u and w, fig. 1 of the plate, when the parallelogram is square, and through the joint between them, where the joints reach when fully extended, (as in fig. 2); and a similar obser- vation applies to the other side y V. The diagram, fig. 9, contains this circle and the true curve shewn together, with the difference that exists between them, the true curve being num- bered from 1 to 16, and small circles drawn to shew the axle as it goes. It is obvious, that if the joints, which are not on the ground, be by any means guided in this curve, then will the top and bottom joints also be properly guided; and it is by conducting these intermediate joints, that the motion is governed, with less friction than by the curve itself. Because as the curve differs but little from a circle, the means exist of attaching a radius or arm to the centre of each joint, (so that it can turn round,) reaching nearly to the centre of the circle; which the curve resembles, and to place a much smaller curve partly round it, of such figure, that when the arms are by any means caused to point to the centre of the circle in fig. 23, which also represents the centre of the large circle in fig. 9, while a pin in the end of the arms properly traverses this curve, then the joint to which it is attached will be guided in the true curve, 1, 3, 15, 16, &c. in the same way as if it were guided by the curve itself, though with much less friction. But this little curve alone will not restrain the arm in a line with the centre, and the following method has therefore been adopted. The four arms SO, J K, L H, and N P, figs. 15, 16, and 18, have two pins or rollers at the end of each of them, (not oppo- site, but reversed,) which guide the motion. One of these pins is on one side of the arm, and one on the other, in contrary directions, and at a small distance from each other, as shewn, and they work round two similarly curved guides, 1, 2, 3, 4, ſigs. 1, 2, and 9, fixed in the carriage, but whose curvature is also reversed. One of these guides in the plate hides the other, and which is itself put out of sight by its own back, but both are dotted to shew them ; and they are fixed to the car- riage, the two facing each other, (as a box faces its lid,) leav- ing a space between them for the arms, which work between the two, one of the pins or rollers of the arms working in the one curve, and one in the other, each bearing half the pressure. Especial care must be taken not to fix the pins on the wrong side of the arms, or the curves with the wrong faces to the car- riage and parallelogram. Thus in fig. 18, the pins suit, sup- posing the guide, of which the back is seen in fig, 2, to be next to the parallelogram, or when faced, as in the plate, and in fig. 17, they would suit, if the back of the one now seen were nearest to the body, as shewn in the diagram, fig. 9, but the pins being still reversed to each other, the position of the curves not being altered by changing or turning them, or by fixing them end for end. The curves must always be reversed to each other, and there are two ways of reversing them, one answering to arms made as in fig. 18, and the other as in fig. 17. These two rollers then keep each other in their proper position while they work round the small ends of the guide, and during which period they give the proper extension to the feet, thus acting instead of a rail-way. The long part, I, of the guides serves only to conduct the arms to the bearing ends, but scarcely suffers any pressure or friction there. The dark curve in the diagram, fig. 9, is so placed as to answer to the arm 17. The light shaded pin works in the dark curve, and the dark pin in the light curve. '. Though the ends of the guides conduct the arms, it is found necessary to cut off a small portion of these ends where the arms enter, and leave these places; which otherwise would contain asperities injurious to the motion. (See Repertory for June 1821.) Though by such means the scaper loses its guidance for a short space, but to supply its place there are affixed to the upper guide two small curves e, i, f, and g, j, h, fig. 11; and there are attached to the parallelogram four small rollers, a, b, c, d, which at times bear against the outside of e, i,j, and against the inside of g, j, h; the defect being thus re- medied. But the rollers only bear against a small part of these curves, excepting on very unlevel ground, and in that case they keep the parallelogram properly extended, (see the sequel.) While the arms traverse the long part of the guides, they go inclined, as W n, and D q, fig. I l; when to prevent their becoming, by any accident, perpendicular, and striking, the axle L, the lower guide, (but not the upper one,) is furnished with an inside projection m, n, p, q, forming a groove with the guide itself, (but found to require more width near the corners than in any other place,) and in this groove one of the rollers of the arms works, thus keeping the arm properly inclined, and in the same direction, whether the carriage goes from right to left, or left to right. Or the upper guide, instead of the lower, may have such a projection, and then the arms will traverse.in the direction shewn in figs, 2 and 9. But as this inside pro- jection will not serve when the parallelogram is nearly square, two small pins, O and H, fig. 11, are affixed between the upper guide and the curves g, j, h, and e, i, f, which by bearing loosely against a small projection upon each of the arms near P. H. K and O, keep the arms by that means right ; these small pro- jections having the peculiar and required property of causing the arms to enter the end portions of the guides in one posi- tion, and leaving them in another. Though only one guide must have the inside projection m, n, p, q, a small piece in the other, near m and p, is also serviceable in preventing the foot from being pushed back when fully extended, as A, C, fig. 2. In fig. 11, the outside plain line is the exterior of the top guide; the next plain line is the interior; the outside dotted line is the interior of the lower guide; and the inside dotted line is the inside projection. Fig. 10 is an end view of the scaper, the same letters referring to the same parts, and fig. 24 is one of the guides divided into lines of proper lengths, to express its shape. In fig. 2 the scaper is shewn, supposing it jointed with common round axii, and boxes, but in fig. I the pins v, to avoid friction, are so contrived as to roll round within their boxes Gh, upon a rounded. angular side h, where the chief pressure exists, leaving the other two angular sides of the pins to slide, the insides of the boxes then being properly curved, keep the whole steady in its motion. Figs. 12 and 13 are the arms made after the same plan, and in fig. 14 N n is a front view of the pins upon the sides of the parallelogram. In order for the carriage to turn, the front scapers may be made to swing as common wheels; but it is far preferable for each front scaper to swing separately on a perpendicular axis immediately above itself, and then, as great steadiness is required, the guide of the front and back scaper should be connected by two circular pieces sliding within each other, shewn in fig. 21. n, n, S y, v, fig. 20, is a section of the guides, arms, and rollers, which are here suggested, in a peculiar form, to defend themselves from mud. The last species of scaper we have to describe is shewn in figs. 5, 6, and 7. Fig. 7 being a kite view of fig. 5, the top rail of the carriage being removed. This sort of scaper is inferior to the last in point of friction; it is also rather less equable and quiet in its motion, and does not allow so much facility to the carriage in turning, but is of great strength, and better sur- mounts large obstacles when the feet happen to come upon them. It is also more calculated for uneven roads, owing to a peculiar property of changing its form and action according to the ground, so as to surmount those asperities which it does not escape, gradually, and effecting this in every instance while the carriage moves the length of a whole side of the parallele- gram, instead of a small portion, as in the other species. It W H E DICTION ARY OF " W H S 1045 MECHANIC AIL SCIENCE. has also the advantage of always supporting the carriage nearly from the same place, because there are always two feet on the ground at once, excepting when the feet are themselves nearly under the main axle; whereas in all the other species, the points of support greatly vary. a, b, a, figs. 5 and 6, is the carriage. A C, D F, G H, and J L, are the four sides of the parallelogram, jointed at a, f, h, k, l, g : e i and l g are two cross pieces, jointed at l, g, e, and i, bent, as, shewn at L l, g D, fig. 7, e, i, being hidden in this figure; and M. M., Q P, is a standard or piece, which, in a front view, would appear thus | | the at Q. part a showing where it is attached to the frame a, a, and Q representing an axle fastened in the other end of it, upon which goes a large wheel R. R, wide enough to bear on all the sides of the parallelogram in turn, on which it runs. S, V, Q is a lever, one end being jointed to the frame on an axle at V, and the other end jointed to the centre of the parallelogram, with a long tube V at one end, and another tube Q in the other crid ; while one tube works on the axle in the frame at V, and the other on the outside of another tube Q in the cross piece g l. The other cross piece e, i, in this machine, being furnished with an axle to go in the tube in the cross piece g, l. This lever allows the centre of the parallelogram to rise and fall without the carriage. TT is a spring to assist the scaper to change its position from that of fig. 6 to that of fig. 5, the spring being shewn on the other side (for the other scaper) likewise the lever S Q; and as the tube Q must work past the frame a, a, the frame must have an opening in it to allow the axle Q to pass, unless the scaper should be fixed further from the frame, or the tube Q made shorter, or unless the body be placed rather higher than shewn. A d, Cf, G h, and I k, figs. 5 and 6, are four rollers on the end joints of the parallelogram, and ZZ Z is a properly shaped curve, firmly attached to the frame or standard M, into which these rollers pass, causing the feet to come down gently. As this curve bears up the feet, it likewise would slightly raise the carriage; but to prevent this, the sides of the parallelogram on which wheel R runs, though straight for nearly their own length, are a little curved near the ends accordingly. In this sort of scaper, as two feet remain long on the ground at once, it is necessary for the joints to play, to allow the carriage to turn, and a joint, shewn in fig. 25, though too long, shews one way of making them. J H L C is the axle, B A the box, E the axle of the rollers A d, Cf. G. h, and I k, figs. 5 and 6. and FG, fig. 25, are the screws fitting in a groove in the axle, but allowing it to play. Owing to the property in this species of scaper of supporting the carriage always nearly in the same place, they may suit best two to a body, instead of four, and fixed nearly in the middle. One small common wheel may then be placed in front, without bearing more weight than just to balance it, and by means of a swivel, so as to turn. The diagrams, figs. 8, 9, 11, and 24, shew how to project some of the different curves regu- lating the motions, the other curves being also described in the works we have cited. & In order to project the curve IJ L M, figs. 3 and 4, draw a right line o k, fig. 8, equal to the span of the feet taken from the centers of the little circles FG H I, and also draw the cross with the wheels and centers, lettered as in fig. 8. Divide this line into a number of equal parts, call the middle of it 1, and figure towards letter o, 2, 3, 4, 5, 6, 7, 8, 9, and towards k, 16, 15, 14, 13, 12, 11, 10, 9, draw circles the size of the feet round each of these divisions, and also draw a line kf c, touch- ing them, (merely to shew the ground,) then from g erect a perpendicular g i, the height of the cross; at the upper end also draw the foot circle, i, as on the cross, and bisect this line shewn at P, also placing No. 1 at the point of bisection; take then a space from this point P or 1, downward, equal to the parallel distance of the centers of the axii P and Q, fig. 19, and mark a point Q on it. Then proceed by drawing a circle round this point Q, through the middle P of the perpendicular g i. With the distance then, from the top P of the circle PQ, to No. 1 in the line o k in the compasses, fix them at No. 2 in line o k, and intersect the circle PQ in an opposite direction, with the same distance, next from No. 3, line o k, proceed in this way to No. 9; also in the opposite direction of the circle PQ, and line o k, and mark each intersection of circle PQ. 110, - Continue, by numbering the intersections from 1, (in the direc- tion P M K P,) 2, 3, 4, 5, 6, till 16, the little circles representing the axle in its various positions, being drawn in the diagram round the points; and draw right lines, the length of the cross through each of the points, so as to touch line ok, at the same numbers as the numbers of the points through which they pass, representing the legs when they are most perpendicular in their different positions, and the two dotted wheels aſ ac, shew the position of the leg wheels, when two feet bear at once on level ground; and the upper circles, 1, 2, 16, &c. shew part of the direction of the motion of the upper ends of the cross, which if continued, would form a loop on each side, while the lower feet go in a right line. Continue, by taking the distance between the centre of the leg wheel v g and line o k in the compasses; fix one leg of them on each of the numbers in line o k, and with the other compass point mark those limes that are of the same number as the lines in which the compasses are fixed. This will give all the main part of the curve a y, described by the centres of the leg wheels, while these wheels bear the chief weight when the ground is level; and which may also be found by measuring from the circle P, Q, taking the distance v P instead of g v, and proceeding similarly from the numbers as described, marking each of the lines which are between a and y. The use of the remainder of the curve is to keep the axle P of the cross and crank P, Q in its proper direction and velocity, and to support and guide the cross when the feet happen to come on an irregularity of ground, and is found thus:—Take the distance a y, from the intersections on each of the lines numbered 9 in the compasses; fix one leg of them on 9 y line o k, and mark part of a circle q beyond ar, then fix the com- passes with the same span on 10 line o, k, and mark another part of a circle q, a little beyond the last, and proceed thus with No, 11, 12, 13, 14, 15, 16. Then take the distance from 9 in circle PQ, to the intersection 9a, in the compasses; next fix one leg on 10 in circle PQ, and with the other compass point intersect q 10, then from 11, in circle PQ to g 11, and continue thus to q 1 inclusively; this side of the curve will then be found; after which, repeat the operation on the other side, first with the span a y, beginning from 9a, and then by fixing the com- passes on line 8, and marking beyond y, mext at 7, in the same way till 1 inclusively, and number them 8, 7, 6, 5, 4, 3, 2, 1. Coñtinue, by applying the distance from 9 y to 9, in circle PQ, and intersect those marks, always placing one leg of the com- passes in a point of the same number in circle PQ, as the num- ber of the mark that is to be intersected; and this being done, the whole curve described by the centers of the leg wheels on the machine, will be traced by the marks. Circles the size of the leg wheels must then be drawn round all those points, and the several tops will shew the true form of the whole curve. The lower part of the curve, J, K, L, may also be found, by regulating the foot g in a right line, while the crank is turned in the direction it follows when the cross is at work, and at the same time causing the upper edge of the leg wheel v, black- ened, to mark on a board placed behind it, observing to keep the centre of the crank P, without moving too much either to the right or to the left. To find the curvature of the ends of the guides, 1, 2, 3, 4, figs. 1 and 2:—First, let the curve 1, 16, &c. fig. 9, which the centers of the joints describe, be found, and which may be shewn, by placing a board behind the joints, (blackened,) while the ground feet are drawn along a straight line the same length as the span of the feet, and the axle being kept still. Or this curve may be found thus:–Describe a circle in the figure which represents the parallelogram when square, touching all the four sides; then fix the points of three needles in a right line in a flat ruler, the same distance apart as the distance between the joints Fw, or F w. Figs. 1 and 2 guide one ex- treme point along the top or bottom straight sides, 1, 9, 16, conducting the middle point in the circle, when the other extreme point will describe the curve required. Or it may be projected simply with the compasses, by equally dividing the top and bottom sides of the square, and by numbering them in contrary directions, as in fig. 9. Then by fixing one compass point in each of these divisions, on each side 1, 9, 16, &c. with the span of the side of the square between the compasses, and marking with the other point of the compasses, a number of 12 K. 1046 W H I W H I DICTION ARY OF MECHANICAL SCIENCE. segments of circles near the circle 1, 9, 16, so that each seg- ment gets intersected by one of the same number from the opposite side; and these intersections, numbered in the figure, to shew from whence they originate, will also point out the curve sought for; from which proceed to find the small end curves, according to the following plan :— : . . t Into one end of a flat ruler, the full length of the radius of circle 1, 9, 16, fix the point of a needle answering to the centre of the arm, and near the other end fix two needle points, situate like the centres of the pins of the arms, and between them cut a groove pointing to the one needle point, which groove is to be caused to work and to slide on another needle, fixed in the centre of circle 1, 9, 16, while the single needle point is guided continually by the large curve near circle 1, 9, 16, and then will the two needle points trace out two small curves; round the boundary of each of which, must then be drawn a number of small circles, the size of the pins or rollers, so that the insides of them will shew the true shape of the ends of the curves. Instead of the ruler with points, &c. a piece of transparent horn with holes may be found convenient. The shape of that part of the curve which connects the two end portions together, is of no decided figure, but still requires great exactness, and is found by repeated trials ; which being done, two solid curves are fitted to the figures of the whole guides, reversedly screwed together, and this serves for a model or core on which to make and affix the guides them- selves; taking care that the guides be fixed exactly horizon- tally; and for which purpose, draw a line from 9 to 9, fig. 9, horizontally, (supposing the figure in its natural position,) marking the double guide into two equal and similar portions. This then must be fixed, so that the two halves into which the line cuts the curve, be similarly siuate to the two sides of the figure of the diagram, the centre, I, being in the middle. The shape of the curves g, j, k, and e, i, f, fig. 11, is easily found by causing the feet to move in a right line, and observing the trace of the rollers on a board properly fixed, during the short time when the arms become useless, and also whilst the feet are approaching or leaving the level line of the ground ; which part of the curves the rollers a a, c b, will bear against as they pass when the ground is unlevel, the feet being by this means kept in their proper course. The curve ZZ Z, figs. 5 and 6, is found at pleasure, so as to give an easy motion to the feet, in approaching and leaving the ground ; and owing to the circular motion of the lever V S the two halves, ZZ and Z, will differ. But this curve, while it bears up the feet, tends also to raise the parallelogram, the sides of which are therefore very slightly curved, to prevent this evil from taking place; and the curvature is found, by causing the feet to move in a right line, observing the shape described by the flat face of the wheel R. on the sides of the parallelogram. In the diagram, fig. 9, the feet are shewn dotted, of a better shape than those in figs. 1 and 2, which construction prevents their suddenly falling off by any obstacle. Fig. 26, is a screw for the nuts, or for other purposes, in which the side of the thread bearing the pressure is perpendi. cular, and the other side doubly inclined, thus uniting the strength of an angular thread to the advantage of a flat thread, viz. of preventing the nuts from bursting. WHERRY, a name given to several kinds of light boats used on the sea-coast and up rivers. Wherry is also applied to some decked vessels used in fishing, in different parts of Great Britain and Ireland. WHIP, among Sailors, a sort of small tackle, formed by the communication of a rope with a single immoveable block, or with two blocks, one of which is fixed and the other moveable; used to hoist up light bodies, such as empty casks, &c. WHIP, or Whip Staff, is a piece of timber in form of a strong staff, fastened into the helm for the steersman, in small ships, to hold in his hand, in order to move the rudder, and direct the ship. - WHIRLING TABLE, a machine intended to represent the Several phenomena in philosophy and nature, as the principal laws of gravitation, and of the planetary motions. WHIRLPOOL, an eddy, vortex, or gulf, where the water is continually turning round. In rivers these are very com- mon from various accidents, and are usually very trivial and of little consequence. In the sea they are more rare, but more dangerous. Sibbald has related the effects of a very remarkable marine whirlpool among the Orcades, which would prove very dangerous to strangers, though it is of no consequence to the people who are used to it. This is not fixed to any particular place, but appears in various parts of the limits of the sea, among those islands. Wherever it appears, it is very furious, and boats, &c. would instantly be drawn in and perish thereby, but the people who navigate them are prepared for it, and always carry an empty vessel, a log of wood, or a large bundle of straw, or some such thing, in the boat with them ; and as soon as they perceive the whirlpool, they toss the article within its vortex, and thus keep themselves out of it. This substance, whatever it be, is immediately received into the centre and carried under water; and as soon as this is done, the surface of the place where the whirlpool was, becomes smooth, and they row over it with safety, and in about an hour they see the vortex begin again in some other place, usually about a mile distant from the other. . - WHIRLS, small hooks fastened into cylindrical pieces of wood, which communicate by means of a leather strap with a spoke-wheel, whereby three of them are set in motion at once; they are used for the spinning of yarn for ropes. WHIRLWIND, is a wind that rises suddenly, and is exceeding rapid and impetuous when risen, but soon spent. There are divers sorts of whirlwinds distinguished by their peculiar names, and the Prester, Typho, Turbo. Exhydria, and Ecnephias. The prester is a violent wind, breaking forth with flashes of lightning. This is rarely observed, and scarce ever without the ecnephias. Seneca says it is a typho, or turbo rekindled, or ignited in the air. A typho or vortex, most properly called whirlwind, or hurricane, is an impetuous wind, turning rapidly every way, and sweeping all round the place. It usually descends from on high, and is frequent in the eastern ocean, chiefly about Siam, China, &c. which renders the navi- gation of those parts very dangerous. The exhydria is a wind bursting out of a cloud with a great quantity of water. This only seems to differ in degree from the ecnephias which is frequently attended with showers. The ecnephias is a sudden and impetuous wind breaking out of some cloud, frequent in the Ethiopic sea, particularly about the Cape of Good Hope, and is generally called by seamen a travado. Dr. Franklin, in his physical and meteorological observations, supposed a water-spout and a whirlwind to proceed from the same cause, their only difference being, that the latter passes over the land, and the former over the water. This opinion is corroborated by M. de la Pryme, in the Philosophical Trans- actions, where he describes two spouts observed at different times in Yorkshire, whose appearances in the air were exactly like those of the spouts at sea, and their effects the same as those of real whirlwinds. Whirlwinds have generally a pro- gressive as well as a circular motion; so had what is called the spout at Topsham, described in the Philosophical Transactions; and this also by its effects appears to have been a real whirl- wind. Water-spouts have also a progressive motion, which is more or less rapid, being in some violent, and in others barely perceptible. Whirlwinds generally rise after calms and great heats; the same is observed of water-spouts, which are there- fore most frequent in warm latitudes. The wind blows every way from a large surrounding space to a whirlwind. Three vessels, employed in the whale fishery, happening to be be- calmed, lay in sight of each other at about a league distance, and in the form of a triangle. After some time a water-spout appeared near the middle of the triangle, when a brisk gale arose, and every vessel made sail. It then appeared to them all, by the trimming of their sails, and the course of each vessel, that the spout was to leeward of every one of them ; and this observation was further confirmed by the comparing of ac- counts, when the different observers afterwards conferred about the subject. Hence whirlwinds and water-spouts agree in this particular likewise. But if the same meteor which appears a water-spout at sea, should in its progressive motion encounter and pass over land, and there produce all the pheno- mena and effects of a whirlwind, it would afford a stronger conviction that a whirlwind and a water-spout are the same W H I W H I 1047. DICTIONARY OF MECHANICAL SCIENCE. thing. An ingenious correspondent of Dr. Franklin gives (as follows) one instance of this, that fell within his own observa- tion at Antigua, and which convinced him that a water-spout is a whirlwind :—There appeared not far from the mouth of the harbour of St. John’s, two or three water-spouts, one of which took its course up the harbour. Its progressive motion was slow and unequal, not in a straight line, but, as it were, in jerks and starts. When just by the wharf, I stood about one hun- dred yards from it. There appeared in the water a circle of about twenty yards’ diameter, which to me had a dreadful though pleasing appearance. The water in this circle was violently agitated, being whisked about and carried up into the air with great rapidity and noise, and reflected a lustre as if the sun shined bright on that spot, which was more conspicuous, as there appeared a dark circle around it. When it made the shore, it carried up, with the same violence, shingles, staves, large pieces of the roofs of houses, &c. and one small wooden house it lifted entirely from the foundation on which it stood, and carried it to the distance of fourteen feet, where it settled without breaking or oversetting ; and what is remarkable, though the whirlwind moved from west to east, the house moved from east to west. Two or three negroes and a white woman were killed by the fall of the timber, which it carried up into the air and dropped again. A fluid moving from all points horizontally, towards a centre, must, at that centre, either mount or descend. If a hole be opened in the middle of the bottom of a tub filled with water, the water wilſ flow from all sides to the centre, and there descend in a whirl. But air, flowing on or near the surface of land, or water, from all sides towards a centre, must, at that centre, ascend, because the land or water will hinder its descent. If these concentring currents of air be in the upper regions, they may indeed descend in the spout or whirlwind ; but then, when the united current reached the earth or water, it would spread, and probably blow every way from the centre. There may be whirlwinds of both kinds ; but from the effects commonly observed, Dr. Franklin suspected the rising one to be most frequent ; when the upper air de- scends, it is perhaps in a greater body, extending wider, as in thunder-gusts, and without much whirling ; and when air descends in a spout or whirlwind, he conceived that it would rather press the roof of a house inwards, or force in the tiles, shingles, or thatch, and force a boat down into the water, or a piece of timber into the earth, than snatch them upwards and carry them away. The whirlwinds and spouts are not always, though most frequently, in the day-time. The terrible whirl- wind which damaged a great part of Rome, June 11, 1749, happened in the night, and was supposed to have been pre- viously a water-spout, it being asserted as an undoubted fact, that it gathered in the neighbouring sea, because it could be traced from Ostia to Rome. This whirlwind is said to have appeared as a very black, long, and lofty cloud, discoverable, notwithstanding the darkness of the night, by its continually lightning, or emitting flashes on all sides, pushing along with surprising swiftness, and within three or four feet of the ground. Its general effects on houses were, stripping off thc roofs, blowing away chimneys, breaking doors and windows, forcing up the floors, and unpaving the rooms, (some of which effects seem to agree well with the supposed vacuum in the centre of the whirlwind) and the very rafters of the houses were broken and dispersed, and even hurled against houses at a consi- derable distance, &c. - Doctor Franklin, the better to explain his conceptions, offers the following positions as a foundation for his hypothesis:— “That the lower region of air is often more heated, and so more rarefied, than the upper, and by consequence specifically lighter. The coldness of the upper region is manifested by the hail, which sometimes falls from it in warm weather. That heated air may be very moist, and yet the moisture so equally diffused and rarefied as not to be visible till colder air mixes with it, at which time it condenses and becomes visible. Thus our breath, although invisible in summer, becomes visible in winter.” - . These circumstances acknowledged, he presupposes a tract of land or sea of about sixty miles in extent unsheltered by clouds and unrefreshed by the wind, during a summer day, or the height of about thirty-two feet. perhaps for several days, without intermission, till it becomes violently heated, together with the lower region of the air in contact with it, so that the latter becomes specifically lighter than the superincumbent higher region of the atmosphere, where the clouds are usually floated. He supposes also, that the air surrounding this tract, has not been so much beated dur- ing those days, and therefore remains heavier. The conse- quence of this he conceives should be, that the heated lighter air should ascend, and the heavier descend ; and as this rising cannot operate throughout the whole tract at once, because that would leave too extensive a vacuum, the rising will begin precisely in that column which happens to be lightest or most rarefied, and the warm air will flow horizontally from all parts to this column, where the several currents meeting and joining to rise, a whirl is naturally formed, in the same manner as a whirl is formed in a tub of water, by the descending fluid receding from all sides of the tub towards the hole in the centre. And as the several currents arrive at this central rising column with a considerable degree of horizontal motion, they cannot suddenly change it to a vertical motion ; there- fore, as they gradually, in approaching the whirl, decline from right to curve or circular lines, so, having joined the whirl, they ascend by a spiral motion, in the same manner as the water descends spirally through the hole in the tub before mentioned. . Lastly, as the lower air nearest the surface is more rarefied by the heat of the sun, it is more impressed by the current of the surrounding cold and heavy air, which is to assume its place, and, consequently, its motion towards its whirl is swift- est, and so the force of the lower part of the whirl strongest, and the centrifugal force of its particles greatest. Hence the vacuum which encloses the axis of the wheel, should be greatest near the earth or sea, and diminish gradually as it approaches the region of the clouds till it ends in a point. This circle is of various diameters, sometimes very large. If the vacuum passes over water, the water may rise in a body or column therein to This whirl of air may be as invisible as the air itself, though reaching in reality from the water to the region of cold air, in which our low summer thun- der clouds commonly float; but it will soon become visible at its extremities. The agitation of the water, under the whirling of the circle, and the rising of the water in the commencement of the vacuum. renders it visible below. It is perceived above by the warm air being brought up to the cooler region, where its moisture begins to be condensed by the cold into thick vapour, and is then first discovered at the highest part, which being now cooled, condenses what rises behind it, and the latter acts in the same manner on the succeeding body; where, by the contact of the vapours, the cold operates faster in a right line downwards than the vapours themselves can climb in a spiral line upwards; they climb, however, and as by continual addi- tion they grow denser, they consequently increase their cen- trifugal force ; and being risen above the concentrating cur- rents that compose the whirl, they fly off and form a cloud. It seems easy to conceive, how, by this successive condensation from above, the spout appears to drop or descend from the cloud, although the materials of which it is composed are all the while ascending. The condensation of the moisture con- tained in so great a quantity of warm air as may be supposed to rise in a short time in this prodigiously rapid whirl, is perhaps sufficient to form a great extent of cloud, and the friction of the whirling air on the sides of the column may detach great quantities of its water, disperse them into drops, and carry them up in the spiral whirl mixed with the air. The heavier drops may, indeed, ſly off, and fall into a shower about the spout; but much of it will be broken into vapour, and yet remain visible. As the whirl weakens, the tube may apparently separate in the middle, the column of water subsiding, the superior condensed part drawing up to the cloud. The tube or whirl of air may, nevertheless, remain entire, the middle only becoming invisible, as not containing any visible matter. In the Philosophical Transactions, Dr. Stuart says, “It was observable of all the spouts he saw, but more perceptible of a large one, that towards the end it began to appear like a hollow canal, only black in the borders, but white in the middle; and though it was at first altogether black and opaque, yet the sea I048 W I L w I N DICTIONARY OF MECHANICAL SCIENCE. water could very soon after be perceived to fly up along the middle of this canal like smoke in a chimney.” & "When Dr. Stuart's spouts were full charged, that is, when the whirling pipe of air was filled with quantities of drops and vapour torn off from the column, the whole was rendered so dark that it could not be seen through, nor the spiral ascending motion be discovered ; but when the quantity ascending lessened, the pipe became more transparent, and the ascending motion visible. The spiral motion of the vapours, whose lines intersect each other on the nearest and farthest side of this transparent part, appeared therefore to Dr. Stuart like smoke ascending in a chimney; for the quantity being still too great in the line of sight through the sides of the tube, the motion could not be discovered there, and so they represented the solid sides of the chimney. . - Dr. Franklin concludes, by supposing a whirlwind or spout to be stationary, when the concurring winds are equal; but if un- equal, the whirl acquires a progressive motion in the direction of the strongest pressure. When the wind that communicates this progression becomes stronger above than below, or below than above, the spout will be bent or inclined. Hence the horizon- ta! process and obliquity of water-spouts are derived. WHIRLING TABLE, a machine intended to represent the several phenomena in philosophy and nature, as, the princi- pal laws of gravitation, and of the planetary motions. WHISPERING-PLACES, depend upon this principle : if the vibrations of the tremulous body are propagated through a long tube, they will be continually reverberated from the sides of the tube into its axis, and by that means prevented from spreading till they get out of it; whereby they will be exceed- ingly increased, and the sound rendered much louder than it would otherwise be. WHIST, a well-known game at cards, which requires great attention and silence; hence the name. WHISTON, WILLIAM, an ingenious English mathematician and divine, was born in 1667, and died in 1752, upwards of 84 years of age. He was author of numerous works on philosophy and religion; of the former, his Theory of the Earth, and his Astronomical Lectures, are the only ones which it is necessary to enumerate in this place. - - WHITEHURST, John, an ingenious English mechanic and philosopher, was born in the county of Chester in 1713, and died in 1788, in the 75th year of his age. WHOODINGS, those ends of planks which are let into the rabbets of the stem, the stern-posts, &c. - WIDOW, a woman who has lost her husband by death. In London, and throughout the province of York, the widow of a freeman is by custom entitled to her apparel, and the furniture of the bed-chamber called the widow’s chamber, . WIFE. See HUSBAND and WIFE. WILD (A) RoadstEAD, implies one that is open, or ex. posed to the wind and sea. WILDERNESS, in Gardening, a kind of groove of large trees, in a spacious garden, in which the walks are coumonly made either to intersect each other in angles, or have the ap- pearance of meanders and labyrinths. WILDFIRE, a kind of artificial or factitious fire, which burns even under water, and that with greater violence than out of it. It is composed of sulphur, naphtha, pitch, gum, and bitumen, and is only extinguishable by vinegar mixed with sand and urine, or by covering it with raw hides. Its motion or ten- dency is said to be contrary to that of natural fire, and it always follows the direction in which it is thrown, whether it be down- wards, sideways, or otherwise. Several are of opinion that the ancient Greeks and Romans used this wildfire in their engagements at sea : whether or not that was the case, it was applied against the Saracens in a sea-fight, commanded by Constantine Pogonates, in the Hellespont, and with such effect, that he burnt the whole fleet there with, wherein there were thirty thousand men. Constantine’s successors used it on divers occasions, and with equal advantage; and what is very remark- able, they were so happy as to keep the secret of the compo- sition to themselves, so that no other nation knew it in 960. WILL AND TESTAMENT, is that disposition of property which is made by a person to take place after his decease. Every person capable of binding himself by contract, is * capable of making a will. Also a male infant of the age of fourteen years and upwards, and a female of twelve years or upwards, are capable of making a will respecting personal estates only. But a marriéd woman cannot make a will, unless a power be reserved in the marriage settlement; but whenever personal property is given to a married wo— man, for her sole and separate use, she may dispose of it by will. If a femme sole make her will, and afterwards marry, such marriage is a legal revocation of the will. Wills are of two kinds, written and verbal ; the former is most usual and se- cure. It is not absolutely necessary that a will should be wit- nessed ; and a testatment of chattels written in the testator’s own hand, though it have neither the testator’s name nor seal to it, nor witnesses present at his publication, will be good, provided sufficient proof can be had that it is his hand-writing. By statute 29 Charles II. c. 3, all devises of lands and tenements shall not only be in writing, but shall also be signed by the party so devising the same, or by some other person in his pre- sence, and by his express direction, and shall be witnessed and subscribed in the presence of the person devising, by three or four credible witnesses, or else the testament will be entirely void, and the land will descend to the heir at law. A wiil even if made beyond sea, bequeathing land in England, must be attested by three witnesses. A will, however, devising copy- hold land does not require to be witnessed; it is sufficient to declare the uses of a surrender of such copyhold land made to the use of the will. The party to whom the land is given becomes entitled to it by means of the surrender, and not by the will.—A Codicil is a supplement to a will, or an addition made by the person making the same, annexed to, and to be taken as part of, the will itself, being for its explanation or alter- ation, to add something to, or take something from, the former disposition, and which may also be either written or verbal, under the same restrictions as regards wills. If two wills are found, and it does not appear which was the former or latter, both will be void; but if two codicils are found, and it cannot be ascertained which was the first, but the same thing is devised to two persons, both ought to divide; but where either wills or codicils have date, the latter is considered as valid, and revokes the former. ar WILLOWS, Week's Brake for Barking. The annexed drawing represents a newly invented brake for taking the bark off willows. The object of it is to prevent their being split, as they too often are, in the stripping, on account of the squeezing with the hand. The hand is not to be applied at all in using these brakes, springs being substituted, which do the work better, and a great deal more expeditiously. - Eaplanation of the Drawing.—A A is the frame, made of half-inch round iron, about two inches apart, or closer; B B, brake irons to loosen the rind, l l inches long; C C, screws to adjust the brake irons, according to the size of the rods to be stripped. The wider they are apart on the top, the stiſſer they will work at the bottom ; D F), springs, fixed on with screws at E E ; F, a bar or guide, projecting an inch to prevent the rod from running down, which, when in use, must be the farthest part of the machine from the operator, and down on it the rod must come when worked ; G, a key to keep the brake in its place when erected for use, by passing the end through two staples on a strong stake, provided for the purpose; H to I, fifteen inches; H to K, twenty-one inches, the whole length. The operator is to place himself in a position so as to have a sway of the body, with the left hand on the rod, to bring it down on the guide, by which the brake will be kept clean from the rind, &c. without further trouble. The chief point in making these brakes is, to make sure of the strength and elasticity of the springs. . | • WIN CH, a cylindrical piece of timber, having an axis, whose gå A G g £-jā W I N W I N 1049 DICTION ARY OF MECHANICAL SCIENCE. extremities rest in two channels placed horizontally or perpen- dicularly, and furnished with clicks or pauls. It is turned about by means of a handle resembling that of a grindstone, and is generally employed as a purchase, by which a rope or tackle- fall may be more powerfully applied to any object than when used singly, or without the assistance of mechanical powers. WINGH, is also the name of certain long iron handles by which the chain-pumps are worked. WIND, a sensible current in the atmosphere. The motions of the atmosphere are subject in some degree to the same laws as those of the denser fluids; if we remove a portion of water in a large reservoir, we see the surrounding water flow in to restore the equilibrium ; and if we impel in any direction a cer- tain portion, an equal quantity moves in a contrary direction, from the same cause ; or if a portion, being rarefied by heat or condensed by cold, ascends in the one instance and descends in the other, a counter-current is the visible and natural result; and similar effects are found to follow the same causes in the atmospheric luid. Thus, no wind can blow without a counter or opposite current, nor can any wind arise, without a previous derangement of the general equilibrium ; the general causes of which may be stated as follows: 1. The ascent of the air over certain tracts heafed by the sun. 2. Evaporation causing an actual increase in the volume of the atmosphere. 3. Rain, snow, &c. causing an actual decrease in its volume by the destruction of the vapour. Cur- rents thus produced may be permanent and general, extending over a large portion of the globe: periodical, as in the Indian ocean; or variable, and as it were occasional, or at least uncer- tain, as the winds in temperate climates. General or perma- nent winds blow always nearly in the same direction. In the Atlantic and Pacific oceans, under the equator, the wind is almost always easterly; it blows, indeed, in this direction on both sides of the equator to the latitude of 28°. More to the northward of the equator, the wind generally blows between the north and east; and the farther north we proceed, we find the wind to blow to a more northern direction; more to the southward of the equator, it blows between the south and east; and the farther to the south, the more it comes in that direction. Between the parallels of 28° and 40° south latitude, in that tract which extends from 30° west to 100° east longitude from London, the wind is variable, but it most frequently blows from between the N.W. and S.W. so that the outward bound East- India ships generally run down their easting on the parallel of 36° south. Navigators have given the appellation of trade-winds to these general winds. Periodical WINDS.–Those winds which blow in a certain direction for a time, and at certain stated seasons change, and blow for an equal space of time from the opposite point of the compass, are called monsoons. During the months of April, May, June, July, August, and September, the wind blows from southward over tile whole length of the Indian ocean, viz. be- tween the parallels of 28° N. and 28° S. latitude, and between the eastern coast of Africa and the meridian which passes through the western part of Japan; but in the other months, October, November, December, January, February, and March, the winds in all the northern parts of the Indian ocean shift round, and blow directly contrary to the course they held in the former six months. For some days before and after the change, there are calms, variable winds, and tremendous storms with thunder, &c. Causes of the WIND.—Philosophers differ in their opinions respecting the cause of these periodical winds; but a more probable theory of the general trade-winds is, that they are occasioned by the heat of the sun in the regions about the equator, where the air is heated to a greater degree, and con- sequently rarefied more, than in the more northern parts of the globe. From this expansion of the air ºn these tropical regions, the denser air in higher latitudes rushes violently towards the equator from both sides of the globe. “By this conflux of the denser air, without any other circumstances intervening, a direct northerly wind would be produced in the northern tropic, and a southern one in the other tropic; but as the earth's diurnal motion varies the direct influence of the sun over the surface of the earth, and as by that motion this inſluence is communicated from east to west, an easterly wind would be 111. ern climates. produced if this influence alone prevailed. On account of the co-operation of these two causes at the same time, the trade- winds blow naturally from the N. E on the north, and from the S. E on the south of the line, throughout the whole year; but as the sun approaches nearer the tropic of Cancer in our sum- mer season, the point towards which these winds are directed will not be invariably the same, but they will incline more towards the north in that season, and more towards the south in our winter. * The land and sea breezes in the tropical climates may be considered as partial interruptions of the general trade-winds; and the cause of these it is not very diſſicult to explain. From water being a better conductor of heat than earth, the water is always of a more even temperature. During the day, there- fore, the land becomes considerably heated, the air rarefied, and consequently in the afternoon a breeze sets in from the Sea, which is less heated at that time than the land. On the other hand, during the night the earth loses its surplus heat, while the sea continues more even in its temperature. Towards morning, therefore, a breeze regularly proceeds from the land towards the ocean, where the air is warmer, and consequently more rarefied, than on shore. The cause of the monsoons is not so well understood as that of the general trade-winds ; but what has been just remarked suggests, at least, a probable theory on the subject. It is well known, that at the equator the changes of heat and cold are occasioned by the diurnal motion of the earth, and that the difference between the heat of the day and the night is almost all that is perceived in those tropical regions : whereas in the polar regions the great vicissitudes of heat and cold are occa- Sioned by the annual motion of the globe, which produces the sensible changes of winter and summer; consequently, if the heat of the sun was the only cause of the variation of the winds, the changes, if any, that would be produced by those means in equatorial regions, ought to be diurnal only, but the changes about the pole should be experienced only once in six months. As the eſſects arising from the heat of the sun upon the air must be greater at the equator than at the poles, the changes of the wind arising from the expansion of the air by the sun's rays must be more steady in equatorial than in polar regions. The incontrovertible evidence of navigators proves this truth, that winds are more variable towards the poles, and more constant towards the equator. But in summer, the con- tinual heat, even in high latitudes, comes to be sensibly felt, and produces changes on the wind, which are distinctly percep- tible. In our own cold region the eſſects of the sun on the wind are felt during the summer months ; for while the weather in that season of the year, is fine, the wind generally becomes stronger as the time of the day advances, and dies away towards the evening, and assumes that pleasing serenity so delightful to our feelings. Such are the diurnal changes of the wind. in north- The annual revolution of the sun produces still more sensible effects. The prevalence of the western winds during summer we may attribute to this cause, which is still more perceptible in France and Spain, because the continent of land to the eastward, being heated more than the waters of the Atlantic ocean, the air is drawn during that season towards the east, and consequently produces a western wind. But these effects are much more perceptible in countries near the tro- pics than with us. For when the sun approaches the tropic of Cancer, the soil of Persia, Bengal, China, and the adjoining countries, becomes so much more heated than the sea to the southward of those countries, that the current of the general trade-wind is interrupted, so as to blow at that season from the south to the north, contrary to what it would do if no land was there. But as the high mountains of Africa during all the year are extremely cold, the low countries of India, to the eastward of it, become hotter than Africa in summer, anul the air is naturally drawn thence to the eastward. From the same cause it follows that the trade-wind in the Indian ocean, from April till October, blows in a north-east direction, contrary to that of the general trade-wind in open seas in the same lati- tude ; but when the sun retires towards the tropic of Capricorn, these northern parts become cooler, and the general trade-wind assumes its natural direction. - Having given the most obvious causes of the periodical mon- 12 L. I050 W I N W I N DICTIONARY OF MECHANI CAL SCIENC E. soons in the Indian seas, it is necessary to observe, that no monsoon takes place to the southward of the equator, except in that part of the ocean adjoining to New Holland. There the same causes concur to produce a monsoon, as in the northern tropic, and similar appearances take place. From October till April, the monsoons set in from the N. W. to S. E. opposite to the general course of the trade-wind on the other side of the line: and here also the general trade-wind resumes its usual course during the other months, which constitute the winter season in these regions. It may not be improper to conclude this account of the tropical winds, by enumerating some of the prin- cipal inflections of the monsoons. Between the months of April and October the winds blow constantly from W.S.W. in all that part of the Indian ocean which lies between Madagascar and Cape Comorin, and in the contrary direction from October till April, with some small variation in different places, but in the Bay of Bengal these winds are neither so strong nor so constant as in the Indian ocean. It must also be remarked, that the S.W. winds in those seas are more southerly on the African side, and more westerly on the side of India; but these variations are not so great as to be repugnant to the general theory. . The cause of this varia- tionis, as was before intimated, that the mountainous lands of Africa are colder than the flatter regions of Arabia and India; consequently the wind naturally blows from these cold moun- tains, in the summer season, towards the warmer lands of Asia, which occasions those inflections of the wind to the eastward during the summer months. The peninsula of India lying so much farther to the south than the kingdoms of Arabia and Persia, adds greatly to this effect; because the wind naturally draws towards them, and produces that easterly variation of the monsoon which takes place in this part of the ocean, while the sandy deserts of Arabia draw the winds more directly northward near the African coast. A similar chain of rea- soning will serve to explain any other inflections or variations that may occur in the perusal of books of travel, &c. Variable WINDs.-In the temperate zones the direction of the winds is by no means so regular as between the tropics. Even in the same degree of latitude, we find them often blowing in different directions at the same time; while their changes are frequently so sudden and so capricious, that to account for them has hitherto been found impossible. When winds are violent, and continue long, they generally extend over a large tract of country, and this is more certainly the case when they blow from the north or east than from any other points. By the multiplication and comparison of meteorological tables, some regular connexion between the changes of the atmosphere in different places may, in time, be observed, which may at last lead to a satisfactory theory of the winds. It is from such tables chiefly, that the following facts have been collected. In Virginia, the prevailing winds are between the south- west, west, north, and north-west; the most frequent is the south- west, which blows more constantly in June, July, and August, than at any other season. The north-west winds blow most con- stantly in November, January, and February. At Ipswich in New England, the prevailing winds are also between the south- west, west, north, and north-east; the most frequent is the north-west. But at Cambridge, in the same province, the most frequent wind is the south-east. The predominant winds at New York are the north and west; and in Nova Scotia north-west winds blow for three-fourths of the year. The same wind blows most frequently at Montreal in Canada; but at Quebec the wind generally follows the direction of the river St. Lawrence, blowing either from the north-east or south-west. At Hudson’s Bay, westerly winds blow for three-fourths of the year; the north-west wind occasions the greatest cold, but the north and north-east are the vehicles of snow. It appears from these facts that westerly winds are most fre- quent over the whole eastern coast of North America; that in the southern provinces, south-west winds predominate; and that the north-west become gradually more frequent as we approach the frigid zone. In Egypt, during part of May, and during June, July, August, and September, the wind blows almost constantly from the north, varying sometimes in June to the west, and in July to the west and the east; during part of September, and in vailing wind is the south-west. October and November, the winds are variable, but blow morc regularly from the east than any other quarter; in December, January, and February, they blow from the north, north-west, and west; towards the end of February they change to the south, in which quarter they continue till near the end of March ; during the last days of March, and in April, they blow from the South-east, south, and south-west, and at last from the east; and in this direction they continue during a part of May. In the Mediterranean the wind blows nearly three-fourths of the year from the north; about the equinoxes there is always an easterly wind in that sea, which is generally more constant in spring than in autumn. These observations do not apply to the gut of Gibraltar, where there are seldom any winds except the east and west. At Bastia, in the island of Corsica, the pre- In Syria the north wind blows from the autumnal equinox to November; during December, January, and February, the winds blow from the west and south-west, in March they blow from the south, in May from the east, and in June from the north. From this month to the autumnal equinox, the wind changes gradually as the sun approaches the equator, first to the east, then to the south, and lastly to the west. At Bagdad the most frequent winds are the South-west and north-west ; at Pekin the north and the south ; at Kamtschatka, on the north-east coast of Asia, the prevailing winds blow from the west. In Italy the prevailing winds differ considerably, according to the situation of the places where the observations have been made; at Rome and Padua they are northerly, at Milan easterly. All that we have been able to learn concerning Spain and Portu- gal is, that on the west coast of these countries, the west is by far the most common wind, particularly in summer; and that at Madrid the wind is north-east for the greatest part of the sum- mer, blowing almost constantly from the Pyrenean mountains. At Berne in Switzerland, the prevailing winds are the north and west; at St. Gothard the north-east; at Lausanne the north- west and south-west. Father Cotte has given us the result of observations made at 86 different places of France; from which it appears, that along the whole south coast of that kingdom the wind blows most frequently from the north, north-west, and north-east ; on the west coast, from the west, south-west and north-west; and on the north coast from the south-west. That in the inte- rior parts of France, the south-west wind blows most frequently in 18 places; the west wind in 14; the north in 13; the south in 6; the north-east in 4; the south-east in 2; the east and north-west each of them one. On the west coast of the Nether- lands, as far as Rotterdam, the prevailing winds are probably the south west, at least this is the case at Dunkirk and Rotter- dam. It is probable also, that along the rest of the coast, from the Hague to Hamburgh, the prevailing winds are the north- west, at least these winds are most frequent at the Hague and at Franeker. The prevailing wind at Delft is the south-east; and at Breda, the north and the east. In Germany, the east wind is most frequent at Gottingen, Munich, Weissenfels, Dusseldorf, Saganum, Erford, and at Buda in Hungary; the south east at Prague and Wurtzburg ; the north-east at Ratisbon ; and the west at Manheim and Berlin. From an average of ten years of the register kept by order of the Royal Society, it appears that at London the winds blow in the following order: Winds. Days. Winds. Days South-west, . . . . . . . . . 112 South-east, . . . . . . . ... 32 North-east, .......... 58 | East, . . . . . . . . . . . . . . . . 26 North-west, . . . . . . . . . 50 | South, . . . . . . . . . . . . . . . 18 West, . . . . . . . . . . . . . . 53 North, ... . . . . . . . . . . . . 16 It appears, from the same register, that the south-west wind blows at an average more frequently than any other wind during every month of the year, and that it blows longest in July and August; that the north-east blows most constantly during Janu- ary, March, April, May, and June, and most seldom during February, July, September, and December: and that the north- west wind blows oftener from November to March, and more seldom during September and October than any other winds. The south-west winds are also most frequent at Bristol, and next to them are the north-east. W I N W I N 1051 DICTION AIRY OF MECHANICAL SCIENCE. The following table of the winds at Lancaster has been drawn up from a register kept for seven years at that place. Winds. Days. Winds. Days. South-west, ......... 92 South-east, ... . . . . . . . 35 North-east, . . . . . . . . . . 67 North, . . . . . . . . . . ... 30 South, . . . . . . . . . . . . . . 51 North-west, .......... 26 West, . . . . . . . . . . . . . . . 41 East, . . . . . . . . . . . . . . . . 17 The following table is an abstract of nine years’ observations made at Dumfries by Mr. Copland: Winds, - Days. Winds. Days. South, . . . . . . . . . . . . . . 82% North, ... . . . . . . . . ... 36% West, ............... 69 North-west, ........ 25% East, . . . . . . . . . . . . . . 68 | South-east, ........ . 28% South-west, . . . . . . . . 50% | North-east, ........ . 14% The following table is an abstract of seven years’ observations made by Dr. Meek at Cambuslang, near Glasgow : Winds. Days. Winds. Days. South-west, ........ 174 North-east, ......... 104 North-west, . . . . . . . . 40 South-east, . . . . . . . . . 47 It appears from the register from which this table was ex- tracted, that the north-east wind blows much more frequently in April, May, and June, and the south-west in July, Au- gust, and September, than at any other period. The south- west is by far the most frequent wind all over Scotland, especially on the west coast. At Saltcoats, in Aryshire, for instance, it blows three-fourths of the year; and along the whole coast of Murray, on the north-east side of Scotland, it blows for two-thirds of the year. East winds are common over all Great Britain during April and May ; but their influence is felt most severely on the eastern coast, t The following table exhibits a view of the number of days during which the westerly and easterly winds blow in a year at different parts of the island. Under the term westerly are included the north-west, west, south-west, and south; the term easterly is taken in the same latitude. Years of Placea Wind. . Observation. **** Westerly. | Easterly. 10 London,. . . . . . . e ‘s e º e o e º e s & º º º 233 132 7 Lancaster, . . . . . . . . . . . . . . . . . . 21 6 I 49 51 Liverpool, . . . . . . . . . . . . . . . . . . 190 175 9 Du mfries, . . . . . . . . . . . . . . . . . . 227-5 137'5 10 Branxholm, 54 miles south- \ 232 133 - west of Berwick, . . . . . . . . $ 7 Cambuslang. . . . . . . . . . . . . . . . . 214 15.1 S Hawkhill, near Edinburgh,. . . . . 229'5 135°5 Mean . . . . . 2203 144*7 In Ireland the south-west and west are the grand trade- winds, blowing most in summer, autumn, and winter, and least in spring. The north-east blows most in spring, and nearly double to what it does in autumn and winter. The south-east and north-west are nearly equal, and are most frequent, after the south-west and west. ** - At Copenhagen the prevailing winds are the east and south- cast; at Stockholm, the west and north. In Russia, from an average of a register of 16 years, the winds blow from Novem- ber to April in the following order: W. N. W. E. S.W. S. N.E. N. S.E. Days 45 26 23 22 20 19. 14 12 and during the other six months, W. N.W. E. S.W. S. N.E. N. S.E. Days 27 27 19 24 22 15 32 18 The west wind blows during the whole year 72 days; the north-west 58; the south-west and north 46 days each. During summer it is calm for 41 days, and during winter for 21. In Norway, the most frequent winds are the south, the south-west, and the south-east. The wind at Bergen is seldom directly west, but generally south-west or south-east; a north-west, and especially a north-east wind, are but little known there. From the whole of these facts, it appears that the most frequent winds on the south coasts of Europe, are the north, the north- east, and north-west, and on the western coast the south-west : that in the interior parts, which lie more contiguous to the Atlan- tic ocean, south-west winds are also most frequent; but that easterly winds prevail in Germany. Westerly winds are also more frequent on the north-east coast of Asia. It is probable that the winds are more constant in the south temperate zone, which is in a great measure covered with water, than in the north temperate zone, where their direction must be frequently interrupted and altered by mountains and other causes. M. De la Caille, who was sent thither by the French king to make astronomical observations, informs us, that at the Cape of Good Hope the principal winds are the south-east and north- west; that other winds seldom last longer than a few days; and that the east and north-east winds blow very seldom. The south-east wind blows in most months of the year, but chiefly from October to April ; the north-west prevails during the other six months, bringing along with it rain, and tempests, and hurricanes. Between the Cape, of Good Hope and New Hol- land, the winds are commonly westerly, and blow in the follow- ing order: north-west, south-west, west, north. In the Great South Sea, from latitude 30° to 40° south, the south-east trade-wind blows most frequently, especially when the Sun approaches the tropic of Capricorn ; the wind next to it in frequency is the north-west, and next to that is the south- west. From south latitude 40° to 50°, the prevailing wind is the north-west, and next the south-west. From 80° to 60°, the most frequent wind is also the north-west, and next to it is the west. Thus it appears that the trade-winds sometimes extend farther into the south temperate zone than their usual limits, purticularly during summer; that beyond their influ- ence the winds are commonly westerly, and that they blow in the following order: north-west, south-west, west. Such is the present state of the history of the direction of the winds. In the torrid zone they blow constantly from the north-east on the north side of the equator, and from the south-east on the south side of it. In the north temperate zone they blow most fre- quently from the south-west; in the south temperate zone from the north-west, changing, however, frequently to all points of the compass ; and in the north temperate zone blowing parti- cularly, during spring, from the north-east. - Force and Velocity of the Wind.—As to the velocity of the wind, its variations are almost infinite; from the gentlest breeze to the hurricane which tears up trees and blows down houses. It has been remarked that our most violent winds take place when neither the heat nor the cold is greatest; that violent winds generally extend over a great tract of country, and that they are accompanied by sudden and great falls in the mercury of the barometer, The reason appears to be, that violent winds succeed the precipitation in rain of a large quantity of vapour, which previously constituted a part of the bulk of the atmo- sphere; and this precipitation cannot take place when the general temperature approaches to either extreme. The wind is sometimes very violent at a distance from the earth, while it is quite calm at its surface. On one occasion Lunardi went at the rate of 70 miles an hour in his balloon, though it was quite calm at Edinburgh when he ascended, and continued so during his whole voyage. The same thing happened to Garnerin and his companion in their aerostatic voyage to Colchester; they having been carried from London to Colchester, a distance of at least 60 miles, in three quarters of an hour, making the velo- city of the wind, at that time, 80 miles per hour, or 14 mile per minute. This again may be illustrated by the motions of dense fluids, which are always impeded in the parts contiguous to the sides and bottoms of the vessels; and the same thing hap- pens in tide rivers, where the boatman, when he wishes to proceed with the tide, commits himself to the middle of the stream ; but when he has to strive against it, he keeps close to the shore. It is, therefore, not the upper parts of the atmosphere which are - accelerated, but the lower are retarded by friction against the surface of the earth. The following table, drawn up by Mr. Smeaton, will give the reader a pretty precise idea of the velocity of the wind in dif. ferent circumstances: 1052 W H N W I N DICTIONARY OF MECHANICAL SCIENCE. - Miles per Feet per | Perpendicular Force on one square Foot, in . Hour. Second. Avoirdupois Pounds and Parts. I 1°47 •005 Hardly perceptible. 2 2-93 020 f; - 3 4'4 '044 : Just perceptible. 4 5'87 •079 5 7-33 • 123 } Gently pleasant. 10 14.67 *492 e 15 22. 1° 107 } Pleasant, brisk. º 20 29.34 1968 t : slz 25 §§§ $º, ; Very brisk. 30 44' 01 4'429 ) ris o 35 3. 6.62%; High wind 40 58.68 7.873 wr, - º 45 66-01 9-963 $ Very high wind. 50 73'35 | 12:300 Storm or tempest. 60 88:02 || 17-715 Great storm. 80 117:36 31°490 Hurricane, - o Hurricane that tears up trees, and 100 1467 49.200 } carries buildings before it. WIND-Gage. See ANEMOMETER, where the velocity of the wind is fully treated of. - - WIND, with regard to a ship's course, is termed a foul wind, or a fair wind, a scant wind or a leading wind; these terms being respectively opposed to each other. - WIND's Eye, implies the direct point from which the wind blows. - Between Wind and Water, signifies that part of a ship's bot- tom which is frequently brought above the water by her agita- tion when at sea. WIND Sails, in a ship, are made of the common sail-cloth, and are usually between 25 and 30 feet long, according to the size of the ship, and are in the form of a cone ending obtusely. WINDAGE, the difference between the diameter of a piece of artillery, and the diameter of the shot or shell corresponding thereto. WINDING A CALL, the act of blowing or piping on a boat. swain's whistle, so as to communicate the necessary orders of hoisting, heaving, belaying, veering away, &c. WINDING Tackle, a name usually given to a tackle, formed of one fixed triple block, and one double or triple moveable block. It is principally employed to hoist up any weighty materials, such as the cannon, into or out of a ship. WINDL ASS, a machine used in merchant-ships instead of a capstan, to heave up the anchors from the bottom, &c. It is a large cylindrical piece of timber, moving round on its axis in a vertical position, and is supported at its two ends by two pieces of wood, called knight-heads, which are placed on the opposite sides of the deck near the fore-mast; it is turned about by levers, called handspikes, which are for this purpose thrust into holes bored through the body of the machine. The Iower part of the windlass is usually about a foot above the deck. It is, like the capstan, furnished with strong pauls, to prevent it from turning backwards by the effort of the cable, when charged with the weight of the anchor, or strained by the violent jerking of the ship in a tempestuous sea. The pauls, which are formed of wood or iron, fall into notches cut in the surface of the wind- lass, and lined with plates of iron. Each of the pauls being accordingly hung over a particular part of the windlass, falls eight times into the notches at every revolution of the machine; because their eight notches are placed on its circumference under the pauls : so, if the windlass is twenty inches in diame- ter, and purchases five feet of the cable at every revolution, it will be prevented from turning back, or losing any part thereof, at every seven inches, nearly, which is heaved in upon its surface. As this machine is heaved about in a vertical direc- tion, it is evident that the effort of an equal number of men acting upon it will be much more powerful that on the capstan; because their whole weight and strength are applied more readily to the end of the lever employed to turn it about; whereas, in the horizontal movement of the capstan, the exer- tion of their force is considerably diminished. It requires, however, some dexterity and address to manage the handspike to the greatest advantage; and to perform this, the sailors must all rise at once upon the windlass, and, fixing their bars therein, give a sudden jerk at the same instant, in which movement they are regulated by a sort of song or howl pronounced by one of their number. - - - Spanish WINDLAss, is a machine formed of a handspike and a small lever, usually a tree-nail, to set up the top-gallant rigging, | or for any other short steady purchase. WINDMILL. See MILL. WIND-RODE, is a term applied to a ship, which, riding where the wind and tide are opposed to each other, is forced by the violence of the former to remain to leeward of her anchor. WIND-SAIL, a sort of wide tube or funnel of canvass, employed to convey a stream of fresh water downwards into the lower apartments of a ship, being let down through the hatches, and kept extended by means of several wooden boops; the upper part is open on one side, which is braced to the wind so as to receive the full current of it, which fills the tube, and rushes downward into the lower regions of the ship. Ships of war have generally, in hot climates, three or four of these wind- sails, for the preservation of the crew’s health. WINE. All wines contain an acid, alcohol, tartar, extract, aroma, and colouring matter. The presence and nature of each of these principles may be ascertained in the following way: 1. Acid. All wines, even the softest and mildest, redden litmus, and therefore contain an acid. This abounds, however, chiefly in the thin wines of wet and cold climates, where the grape juice or must contains but a small portion of sugar. When wine has been boiled to extract the brandy, the liquor which remains in the still, and is thrown away as useless, is a sour nau- seous fluid with an acrid and burnt flavour. When filtered, and allowed to remain at rest for a time, it deposits a good deal of extractive matter, becomes covered with mould, and then con- tains a notable quantity of acetous acid, which may be separa- ted by distillation. The acid is however not entirely acetous, at least not till after standing a considerable time, for it preci- pitates and forms an insoluble salt with lime water, and with the insoluble salts of silver, lead, and mercury, appears to be the malic acid mixed with a little citric, both of which are converted into vinegar by spontaneous decomposition. The wines that contain the greatest quantity of these acids yield the worst brandy, nor is there any method yet known of sepa- rating or neutralizing the acid without materially injuring the quality, or lessening the quantity of the ardent spirit. 2. Alco- hol, The existence of this principle, and mode of extraction by distillation, has been described under the article DISTILLATION. The quantity of alcohol varies prodigiously. The strong, rich, full-bodied wines of the warmer wine countries will yield as much as a third of ardent spirit; whilst the thin light wines will often give no more than about one sixteenth of the same strength. 3. Tartar. This substance has also been fully de- scribed in its proper place. Tartar is not altogether a product of the fermentation of wine, since it is contained in must, though in small quantity. 4. Extract. Must contains an abundance of extractive matter, which materially assists the fermentation, and is afterwards found, in part at least, in the lees, but an- other portion may be obtained from the wine by evaporation. It is also extract that mixes with and colours the tartar. By age the quantity of extractive matter diminishes. 5. Aroma, All wines possess a peculiar and grateful smell, which would indi- cate a distinct aromatic principle, but it has never been exhi- bited in the form of essential oil, or condensed in any smaller quantity by distillation or any other mode. To give wine all its aroma, it should be fermented very slowly. 6. Colouring matter. The husk of the red grape contains a good colour, which is extracted when the entire fruit is pressed, and becomes dissolved in the wine when the fermentation is complete. Many substances will separate the colour. If line water is added to high-coloured wine, a precipitate is formed of malat of lime, that carries down with it all the colouring matter, which cannot again be separated either by water or alcohol. But if wine alone is evaporated gently to dryness, and the residue treated with alcohol, the colouring matter dissolves therein. We may add, too, that the natural colour of wine is entirely and speedily destroyed by the addition of hot well-burnt charcoal in pretty W H I W H I DICTIONARY OF MECHANICAL SCIENCE. 1053 fine powder. The colour of red wine, in the state in which we receive it, is not entirely that of the grape, but is given by other colouring substances, which however are quite innoxious. WIN es, Raisin.—These wines are made of various kinds of fruit; of Malaga's, Belvidere's, Smyrna's, raisins of the sun, &c. But the fruit that produces the best wines is black Smyrna's, their juice being the strongest, and the fruit clearest from stalks : for the stalks in Malaga’s and Belvidere’s are apt to give the wine a bad flavour, and will always throw an acid on it; for the stalks of all fruits are acid ; but the stalks of Smyrna's are so trifling, that after rubbing the fruit between your hands. they will easily sift out. Wine made from this fruit is the colour of Madeira, and has very much the flavour of it. Malaga is the colour and flavour of foreign Malaga, but not mear so strong. Wine made from Belvidere's is strong and very sweet, and, after keeping it four or five years, is very little inferior to old mountain. In order to succeed in making these wines, you ought never to set the steeps in hot weather, because the heat will put the fruit in a fret, which will injure its fer- mentirig kindly. The best time for making is in January or February. Set the steeps in the coldest part of the cellar, still remembering to keep them from the frost. To every gallon of water put five pounds of fruit, if good ; if but indifferent, put six pounds into the steep. Keep stirring them three or four times a day, and let them continue in the steep till the fruit begins to burst, and the stones swim on the top ; which will be in about fourteen or fifteen days. Then strain the liquor from the fruit, and press the fruit very dry, mixing the pressings with the rest of the liquor, and put all together into a cask, and fer- ment it in the following manner. To every pipe of wine take two quarts of solid ale yeast and one ounce of jalap, put them into a can, and into them pour a gallon of the new wine first made hot, whisk them well together, and apply to the pipe, stirring all together very well. If the cask be less than a pipe, propor. tion your yeast and jalap accordingly. When the ferment comes on, you must keep the bung-holes clean, and let the vessel be filled up three or four times a day. Let it ferment ten or twelve days, or till it works clean and white. Then take it off its bottom, which will be very considerable, and put it into a clean cask. You may filter the bottom through a linen rag, and put to the wine. Lay some heavy weight over the bung, and let it stand a day. Then lay on the top of the wine five gallons of molasses spirit, and bung it up close. Leave out the vent-peg a day or two ; then drop it in the hole, and close it by degrees till you have made it quite close. Let it lie in this state for six months, at that time rack it from its bottom into a clean pipe, and you will find it tolerably fine. Then put to it one quart of forcing, and bung it up. Let it lie till within a month of your wanting it; for the longer it lies, the better it will be in body. Then rack it for the last time, (always observing you touch no bottoms,) and put three pints of forcing to it. Stir it well with a paddle, and bung it up. The bottoms you may run through a linen rag as before, and mix with that in the pipe. You may pierce the wine in six or seven days, and you will find it quite fine and bright. To force Raisin Wines.—For one pipe take two quarts of good cider; put half an ounce of ground alum to it, and one ounce of isinglass pulled to small pieces. Beat them well in your can three or four times a day, and let the mixture stand till it becomes a stiff jelly; then break it with your whisk, and add to it two pounds of white sand or stone dust. Then break it up gradually with some of the wine, till you have made the two quarts two gallons; stir it well together, and apply it to the pipe, and bung up close. The sand will carry down with it all the small particles which the isinglass misses, and likewise confine the bottom so as to prevent it from rising. But if you make the wine stronger by allowing a larger quantity of fruit to the gallon, this forcing will not do; for all forcings must be stronger than the body forced, or else the foul parts will not fall; there- fore such wines must be forced with English stum, a quart of which is sufficient for a pipe, one pound of alabaster being beat in with it, and applied as above. English Stum.—Take a five-gallon cask that has been well soaked in water, set it to drain. Then take a pound of roll brimstone, and melt it in a ladle; put as many rags to it as will suck up the melted brimstone. Burn half those rags in the 11 l. dissolve in four or five hours. *. cask, covering the bung-hole so much as that it may have just air enough to keep it burning. When burnt out, put three gal- lons of very strong cider, and one ounce of common alum (pounded and mixt with the cider) into the cask. Keep rolling the cask about five or six times a day for two days. Then take out the bung, and hang the remainder of the rags on a wire in the cask, as near the cider as possible, and set them on fire as before. When burnt out, bung the cask close, and roll it well about three or four times a day for two days; then let it stand seven or eight days, and this liquor will be so strong as to affect your eyes by looking at it. When you force a pipe, take one quart of this liquid, put half an ounce of isinglass to it, beat and pulled to small pieces. Whisk it together, and it will Break the jelly with a whisk, and put one pound of alabaster to it, then dilute it with some of the wine, put it in the pipe, bung it close, and in a day it will be fine and bright. To cure Acid Raisin Wines. The following ingredients must be proportioned to the degree of acidity : if but small, you must use the less ; if a stronger acid, a larger quantity. It must likewise be proportioned to the quantity of wine, as well as to the degree of acidity. Observe, that the cask be nearly full before you apply the ingredients; which will have this good effect, the acid part of the wine will rise to the top immediately, and issue out at the bung-hole, But if the cask be not full, the part that should fly off will still continue in the cask, and weaken the body of the wine. If the cask be full, it will be fit to have a body laid on it in three or four days’ time. We shall here proportion the ingredients for a pipe, supposing it quite acid, so as but just recoverable. Take two gallons of lac, and two ounces of isinglass, boil them a quarter of an hour: strain the liquor, and let it stand till it is cold ; then break it well with your whisk, and put four pounds of alabaster and three pounds of whiting to it. Stir them well together, and add one ounce of salt of tartar to the whole. Mix by degrees some of the wine with it, so as to dilute it to a thin liquor. Apply this to the cask, and stir it well with your paddle. This will imme- diately discharge the acid part from it, as was said before. —When it is off, and quite down, bung it up for three days, then rack it, and you will find part of its body gone off by the strong fermentation. To remedy this, you must lay a fresh body on it in proportion to the degree to which it has been lowered by the above process; always having especial care not to alter the flavour. And this must be done with clarified sugar; for no fluid body will agree with it but what will make it thinner, or confer its own taste; therefore the following is the best manner. To lay a fresh Body on the Wines.—Take three-quarters of a hundred weight of brown sugar, and put into your copper, then put a gallon of lime water to it, to keep it from burning. Keep stirring it about till it boils; then take three eggs, and mash all together with the shells, which put to the sugar. Stir it about ; and as the scum or filth arises, take it off. When quite clean, put it into your can, and let it stand till it is cold before you use it. Then break it with the whisk by degrees, with about ten gallons of wine, and apply it to the pipe. Work it with your paddle for half an hour ; then put one quart of stum forcing to it, which will unite their bodies, and likewise make it fine and bright. You must keep it bunged very close. To cure Raisin Wines that are cloudy.—These wines, if they take a chill, are affected in the same manner with port wines. Like them they will be cloudy, and will have a floating lee in them, which by shaking in a glass will rise in clouds. If any thing be applied to it cold, it will strike a greater chill upon it, and change its true colour to a pale or deep blue one ; to pre- went which, and take off the chill, you must, For a Pipe.—Take one gallon of lac, and one ounce of isin- glass broken in small pieces, three pounds of alabaster, two ounces of sweet spirit of nitre ; boil them together for five or six minutes; stir them, and apply to the pipe as hot as possible. Stir it well in the pipe with your paddle, and in about two hours after bung it close up. Let it lie five or six days, and you will find it quite fine and bright. This will make it a little flat; to remedy which, you must rack it clean from its bottoms, and throw a quart of stum forcing to it. tº To colour Raisin Wines.—Wine made of raisins of the sun is always of the colour of Rhenish, which is almost white. Very 12 MI 1054 W I R. W O L DICTIONARY OF MECHANICAL SCIENCE. often that which is made of Malaga's (especially if the fruit be but indifferent) will, not hold its colour, but must have a colour laid on it. The right colour of raisin, wine is the colour of moun- tain. You must take care that your wine has not a great bot- tom in it; for if it has, it will be longer before it falls fine. In order to lay a mountain colour on your wine, you must take three or four pounds of brown sugar, according to the quantity of wine you want to colour. Put it in an iron pan or iron ladle, set it over the fire, and keep stirring it about. Let it burn in this manner till it is quite black and bitter, which will be about half an hour. If you burn one pound of Sugar, put a quart of boiling hot water to it; stir it about, and let it boil a quarter of an hour longer, then take it off and let it cool. A pint of this mixture is sufficient to colour a pipe of wine; but note, that with every pint you must mix a quarter of an ounce of common alum pounded to a fine powder; which will set the colour so that,it will not subside, otherwise it will fall to the bottom, and have no good effect on the liquor. If you would have your wine of the colour of port, you must take eight ounces of log- wood raspings, four ounces of alkanet root, and one ounce of co- chineal. Infuse them over a slow fire for three hours, strain the liquor from the wood, and keep it boiling. Then burn three pounds of brown sugar as before, and put the coloured liquor to it; boil all together a quarter of an hour longer ; then take it off, and when cold bottle it for use. A pint of this liquor will make a pipe the colour of port wine. You must always remem- ber to set the colour with a quarter of an ounce of common alum, ground or beaten to a fine powder. Wine from Apples.—The Danish chemist, Oersted, has demon- strated, that, of all the fruits which grow in Denmark, the apple, mixed with a great quantity of sugar, produces a drink which more nearly resembles wine than any other substitute. Cher- ries, gooseberries, and other-fruits, from which a vinous liquor is extracted, are not so proper for it. He hopes, before many years, to make very good wine with apple juice and sugar. WINGERS, small casks stowed close to the side in a ship's hold, where the large casks would cause too great a rising in that part of the tier. WINGS, a name given to those parts of the hold and orlop- deck which are nearest to the sides. This term is particularly used in the stowage of the several materials contained in the hold. WINGs, are also the skirts or extremities of a fleet, when ranged in a line abreast, or when forming two sides of a triangle. It is usual to extend the wings of a fleet in the day-time, in order to discover any enemy that may fall in their track; they are, however, commonly summoned by signal to draw nearer to the centre of the squadron before night. WINNOWING MACHINES. Machines of this sort are in pretty general use where thrashing mills, to which they may be attached, are not erected ; they are made on different principles, according to particular circumstances. WIRE DRAWING, is the art of drawing out long bars of metal, by pulling it through holes in a plate of steel, or other fit metallic compound. In order that a wire may be drawn, it is requisite that the metal should have considerable tenacity. Gold, siver, iron, steel, copper, and their compounds, are most commonly used in the arts. The process is of considerable sim- plicity.—A number of holes, progressively smaller and smaller, are made in a plate of steel, and the pointed end of a bar of metal being passed through one end of them, is forcibly drawn by strong pinchers, so as to elongate it by the pressure arising from the re-action of the greatest hole. This is the wire; and it is again passed in like manner through another hole, a little smaller ; and by continuing the process, the wire has its length increased and its diameter diminished to a very great degree. The largest wire may be nearly an inch in diameter, and the smallest ever made was about the one-thousandth part of an inch : but it is said that silver wire has been made one-fifteen- • hundredth of an inch in diameter. The size of these small wires may be ascertained from the weight of a known measure, of length and the specific gravity of the metal; or, less correctly, the wire may be wound round a pin, and the number of turns counted to make a given length. Wires are drawn square, and of other figures in their sector. In particular, they are drawn grooved, so that any small part will form the pinion of a watch or clock-work. As the violent action of the drawing-plate ren- ders the wire hard and brittle, it is necessary to anneal it seve- ral times during the course of drawing. Very small holes are made by hammering up the larger, and the point, in very thin wire, by rolling or crushing the end by a smooth burnishing tool, upon a polished plate. Gold and silver wire is made of cylindrical ingots of silver, covered over with a skin of gold, and thus drawn successively through a vast number of holes, each smaller and smaller, till at last it is brought to a fineness exceeding that of a hair. That admirable ductility which makes one of the distinguishing characters of gold, is no where more conspicuous than in this gilt wire. A cylinder of 48 ounces of silver, covered with a coat of gold only weighing one ounce, as Dr. Halley informs us, is usually drawn into a wire, two yards of which weigh no more than one grain ; whence, 98 yards of the wire weigh no more than 49 grains ; and one sin- gle grain of gold covers the 98 yards; so that the thousandth part of a grain is above one-eighth of an inch long. He also, on computing the thickness of the skin of gold, found it to be asºns part of an inch. Yet so perfectly does it cover the silver, that even a microcope does not discover any appearance of the silver underneath. Mr. Rohault likewise observes, that a like cylinder of silver, covered with gold 2 feet 8 inches long and 2 inches 9 lines in circumference, is drawn into a wire 307,200 feet long, 116,200 times its former length. M. Boyle relates, that eight grains of gold covering a cylinder of silver, are com- monly drawn into a wire 13,000 feet long. Silver wire is the same with gold wire, except that the latter is gilt, or covered with gold, and the other is not. There are also counterfeit gold and silver wires,-the first made of a cylinder of copper silvered over, and then covered with gold, and the second a cylinder of copper silvered over and drawn through iron in the same man- ner as gold and silver wire. Brass wire is made in the same Way. - - WIT, a faculty of the mind, consisting, according to Mr. Locke, in the assembling and putting together of those ideas, with quick- ness and variety, in which any resemblance or congruity can be found, in order to form pleasant pictures and agreeable visions to the fancy. This faculty, the same author observes, is just the contrary of judgment, which consists in the separating carefully from one another, such ideas, wherein can be found the least difference, thereby to avoid being misled, by similitude and affinity, from taking one thing for another. - WITNESS, one who is sworn to give evidence in a cause. If a man is subpoened as a witness upon a trial, he must appear in court, on pain of 100l. to be forfeited to the king, and 10l. together with damages equivalent to the loss sustained by the want of his evidence, to the party aggrieved. But witnesses ought to have a reasonable time, that their attendance upon the court may be of as little prejudice to themselves as possible: and the court of king's bench held, that notice at two in the after- noon to attend the sitting that evening at Westminster, was too short a time. Where a witness cannot be present at a trial, he mav, by consent of the plaintiff and defendant, or by rule of court, be examined upon interrogatories at the judge’s cham- bers. No witness is bound to appear to give evidence in a cause, unless his reasonable expense is tendered him ; nor need he appear till such charge is actually paid him, except he both resides and is summoned to give evidence within the bills of mortality. - - WOLFF or Wol FIU's, CHRISTIAN, an eminent philosopher, born at Breslau, 1679. At Jena university he made a most extraordinary progress, and in 1792 he repaired to Leipsic, where he opened his lectures by a famous dissertation, called “Philosophia practica universalis methodo mathematica con- scripta.” This great man, whose life was devoted to advance science and virtue, died at Halle of the gout in his stomach, 1754, aged 76. His works in Latin and German are more than sixty in number, the best of which known are, A Course of Ma- thematics, 2 vols. 4to. A Dictionary on the Mathematics, &c. WOLFRAM, an ore of tungsten, is found in different parts of Germany, in Sweden, Britain, France, and Spain ; and almost constantly accounpanied by ores of tin. It occurs both massive and crystallized. The primitive form of its crystals is a rectangular parallelopiped, whose length is 8.66, whose | breadth is 5, and thickness 4.33. Colour brown or brownish W O O W O R. 1055 DICTIONARY OF MECHANICAL SCIENCE. black. Streak reddish brown. Powder stains paper with the same colour. Texture foliated. Easily separated into plates by percussion. Specific gravity from 7. to 7-3. Moderately electric by communication. Not magnetic. Infusible by the blowpipe. Forms with borax a greenish globule, and with microcosmic salt a transparent globule of a deep red. WOOD, CUTTING IN, is used for various purposes; as for initial and figured letters, head and tail pieces of books; and even for mathematical schemes and other figures, to save the expense of engraving on copper; and for prints and stamps for papers, calicoes, linens, &c. The invention of cutting in wood, as well as that of copper, is ascribed to a goldsmith of Florence, but Albert Durer and Lucas brought both those arts to perfec- tion. About 200 years ago, the art of cutting in wood was car- ried to a very great pitch, and might even vie for beauty and justness with that of engraving on copper. It has also of late years been much used, and it is convenient where numerous -cheap embellishments are wanted for a work. The figure is drawn upon the wood, and all that part which is to be left white is cut away, and the rest left. A wood-engraving after printing 100,000 is as good as ever ; and the expense in print- ing is not more than that of letter-press. MATERI ALS. Dyeing Wood. General Observations. It being necessary to say something as to the quality, nature, and texture of the wood most fit for dyeing, we shall state our remarks in the following order:—First, the wood mostly used to dye black, is pear-tree, holly, and beech, all of which will take a beautiful black; it should at the same times be observed, not to take wood which has been long cut, or aged, but as fresh as possible ; we have likewise found that after the veneers have had one hour's boil- ing, and taken out to cool, that the colour has struck much stronger. It should likewise be noticed, that after the veneers are dyed, they should be dried in the air and not by the fire, or in a kiln of any kind; as it tends to destroy the colour. Se- condly, in order to dye blue, green, red, or other colours, take clear holly ; put the veneers first in a box or trough with clean water, and let them remain four or ſive days, changing the water once, or twice, as you find occasion ; the water, acting as a purgative in the wood, will bring forth abundance of slime, &c.; let them dry about twelve hours before they are put in the dye ; by observing this, you will find the colour strike quicker, and be of a brighter hue. Fine Black. —Have a chair-maker’s copper fixed, into which put six pounds of chip logwood, and as many veneers as it will conveniently hold without pressing too tight; fill it with water, and let it boil slowly for about three hours; then add half a pound of powdered verdigrise, half a pound of copperas, and four ounces of bruised nut galls, filling the copper up with vinegar as the water evaporates; let it boil gently two hours each day, till you find the wood to be dyed through, which according to the kind will be in more or less time. Fine Blue.—Take a clean glass bottle, into which put one pound of oil of vitriol ; then take four ounces of the best indigo, pounded in a mortar into small lumps ; put them in a phial, (taking care to set the bottle in a basin or earthen-glazed pan, as it will ferment): after it is quite dissolved, provide an earthen or wooden vessel, so constructed that it will convenie:;tly hold the veneers you mean to dye ; fill it rather more than one-third with water, into which pour as much of the vitriol and indigo (stirring it about), as will make a fine blue; which you may know by trying it with a piece of white paper or wood ; put in your veneers, and let them remain till the dye has struck through. Note. The colour will be much better if the solution of indigo in vitriol is kept a few weeks before using it; also the best trough you can use, being either made of common stone like a stone sink, but of proper dimensions, say about four feet by eight or nine inches, which will be sufficiently large for veneers intended to be stained ; or you may procure one made of arti- ficial stone of any dimension, which will not cost so much ; also you will find the colour strike better if, previous to putting your veneers into the blue dye, you boil them in plain water till com- pletely soaked through, and let them remain for a few hours to dry partially, previous to immersing them in the dye. Fine Yellow.—Take of the root of barberry four pounds, reduce it by sawing to dust, which put in a copper or brass See STRENGTH OF trough, add four ounces of turmeric, to which put four gallons of water, then put in as many white holly veneers as the liquor will cover; boil them together for three hours, often turning them ; when cool, add two ounces of aqua-fortis, and you will find the dye strike through much sooner. Bright Green.—Proceed as in the above receipt to produce a yellow ; but instead of adding aqua-ſortis or the brightening liquid, add the vitriolated indigo, as much as will produce the desired colour. Bright Red.—Take two pounds of genuine Brazil dust, add four gallons of water, put in as many veneers as the liquid will cover, boil them for three hours; then add two ounces of alum and two ounces of aqua-fortis, and keep it lukewarm until it has struck through. Purple.—Take two pounds of chip logwood, and half a pound of Brazil dust, add four gallons of water, and after putting in your veneers, boil them well for at least three hours; then add six ounces of pearl ash and two ounces of alum, let them boil two or three hours every day, till you find the colour struck through. Note. The Brazil dust in this receipt is perhaps superfluous, as it only contributes to make the purple of a redder cast, for the pearl-ash does not act upon it to change it from a red to a purple. Orange.—Let the veneers be dyed, by the method given, of a fine deep yellow, and while they are still wet and saturated with the dye, transfer them to the bright red dye, till you find the colour has penetrated equally throughout. WOODY Flb RE, is procured from the wood, bark, leaves, or flowers of trees, by exposing them to the repeated acticn of boiling water, and boiling alcohol. It is the insoluble matter that remains, and is the basis of the solid organized parts of plants. There are as many varieties of woody fibres, as there are plants and organs of plants ; but they are all distinguished by their fibrous texture, and their insolubility. Woody fibre burns with a yellow flame, and produces water and carbonic acid in burning. When it is distilled in close vessels, it yields a considerable residuum of charcoal. It is from woody fibre, indeed, that charcoal is procured for the purposes of life. M. Gay Lussac and Thenard have concluded from their experiments on wood of the oak, that 100 parts contain of carbon, 52-53; of oxygen, 41-78; hydrogen, 5-69. WOOL, the covering of sheep. Each fleece consists of wool of several qualities and degrees of fineness, which the dealers therein take care to separate. The fineness and plenty of our wool is owing in a great measure to the short sweet grass in many of our pastures and downs: though the advantage of our sheep feeding on this grass all the year without being obliged to be shut up under cover during the winter, or to secure them from woives at other times, contributes not a little to it. WGOLCOMBERS. By 35 G. III. c. 124, all those who have served an apprenticeship to the trade of a woolcomber, or who are by law entitled to exercise the same, and also their wives and children, may set up and exercise such trade, or any other trade or business they are apt and able for, in any town or place within this kingdom, without any molestation: nor shall they be removable from such place by the poor laws. WOOLDING, the act of winding a piece of rope about a mast or yard, to support it in a place where it is fished or scar fed, or when it is composed of several pieces united in one solid. Woolding, is also the rope employed in this service. WO OTZ. The metal extracted from some kind of iron ore in the East Indies, apparently of good quality. It contains more carbon than steel and less than cast iron, but from want of skill in the management is far from homogeneous. WORD, W Atch, is a peculiar word that serves for a token and mark of distinction given out in the orders of the day in time of peace, but in war every evening in the field, by the gene- ra! who commands, and in garrison by the governor, or other officer commanding in chief, to prevent surprise, and hinder an enemy, or any treacherous person, from passing backwards and forwards. It may be changed whenever circumstances render it necessary. Its importance depends upon its being known only to the party interested in keeping it a secret. To commu- nicate it to the enemy is a capital offence. Word, in Language, an articulate sound representing some idea or conception of the mind. The copiousness of the English * DICTIONARY OF MECHANICAL scIENCE. W O U v language is prº r < * * * * ~ * - : * * * - in Johnson's Dictionary: Artibles 3-Nouns substantive 20409– *º- Swed by the following enumeration of the words - *.x Adjectives 9053—Pronouns 41—Verbs 7880; that is, active | 5445; neuter 2425; passive l; defective or imperfect 5; aux- iliary 1 ; impersonal 3—Verbal noun 1—Participles 38—Parti- cipial adjectives J25—Participial nouns 3–Adverbs 496; Ad- verbs in ly 2096; total 2592—Prepositions 69—Conjunctions 19—Interjections 68.—Total 40,301. - It must be remarked, however, that in this list many of the compound words are not reckoned; that the participles are those only having no verbs to which they may be referred, as Beloved ; that though so few verbal and participial nouns are stated by Johnson, yet every active participle may supply one of the former description, and every verb one of the latter; and that both these (verbal and participial nouns) seem to be merely different applications of a true gerund. WORK (To), to direct the movements of a ship, by adapting the sails to the force and direction of the wind. A ship is also said to work when she strains and labours heavily in a tem- pestuous sea, so as to loosen her joints or timbers. To Work Bouble Tides, a phrase used inaithe dock-yards, implying that the people perform the work of three days in two. To Work up Junk, to draw yarns from old cables, &c. and there with to make foxes, points, gaskets, sinnet, or spun-yarn. WORKING IN HARVEST. A person may go abroad to work in harvest, carrying with him a certificate from the minis- ter, and one churchwarden or overseer, that he has a dwelling- house, or place in which he inhabits, and that he has left a wife and children, or some of them there (or otherwise as his condi- tion shall require), and declaring him an inhabitant there. WORKING to WINDw ARD, the operation by which a ship endeavours to make a progress against the wind. WORMING, the act of winding a rope spirally about a cable, so as to lie close along the interval between every two strands; a smaller rope is wormed with spun-yarn. It is generally used as a preparative for serving, and causes the service to lie smooth and round. This is also called Link- Worming. Cables may frequently be preserved by means of chains twisted round them in the following manner:—'Take three chains of about fifteen fathoms each in length, all of an equal size, and proportioned in thickness to the nature of the case, Let them be wound round the cable, so that they may project sufficiently to receive the greatest part of the friction, one end of them being fastened to the ring of the anchor, and each chain being from thence wormed round its respective hollow or channel of the cable, so as not to check it from stretching. Fasten the other ends of the chains to the cable. It is not necessary that the chains should be very heavy, but extremely advisable that the links should be short, because they will be thereby more pliant, and worn much easier. These chains will completely guard the cable against the chafing of the rocks, and they may be put on in a few minutes, so that it is unnecessary to have them fitted on, but when it is probable they may be really serviceable. A due attention to shortening cables at the slack of the tide, and veering out as it flows, must also be highly important to prevent their being damaged. But it frequently happens that cables are suffered to kink, as it is called, through in attention to these circumstances, and to avoid a little trouble. If the wind should freshen when they are in this condition, though the cables be ever so good, the first foul sea that comes against them is almost sure to occasion their snapping; and vessels may be driven on shore, and much damaged, at least, if not totally lost, before they can possibly be brought up to other anchors, that may not always be in a state of readiness; for if there be an in attention and carelessness in one respect, there may be the same probably in others of equal importance. As the weight of the three chains, even for a large cable, will not exceed 500 pounds weight, the only diffi- culty which remains to be obviated will arise from the smallness of the hawse-holes, but these could be enlarged in vessels that shall deem it of sufficient moment to make the trial, and with the additional resistance of a boy or spare man at the head of the vessel, to cast off the chains as they come up, and hand them in above, all inconvenience will be removed. Admitting, indeed, that it may take up a few minutes more to weigh an anchor so secured than a common one, surely this can be no argument against a measure that tends to preserve and ensure the safety of the vessel and ship's company. * It may not be improper to recommend further, in high lati- tudes, where ice may cut or damage the cables while riding at anchor, the use of three other chains of the same nature as the preceding, but not more than five or six fathoms in length. These may be wormed round the cables in the same manner at the surface of the water, and will be an excellent means of guarding them from the ice, so as either to prevent its wounding them, or chafing them quite asunder: a circumstance which is not unprecedented in our harbours or rivers, but which fre- quently happens on the continent of Europe. WORM, an instrument used to pieces of artillery, to draw the charge, or to take out the bottom of the cartridge, which sometimes remains in the chamber after firing, and which, by being on fire, might explode the next charge while being ram- med home, whereby the man would probably lose both his hands; hence it is indispensably requisite that a gun should be wormed at least every third discharge. - WoRM-eaten, the state of a plank, or of a ship's bottom, when a number of cavities are made in it by a particular kind of worm which abounds in the tropical climates. WORMS. See W ERMES, - * - WORSTED, a kind of woollen thread, which in the spinning is twisted harder than ordinary. It is chiefly used either wove or knit into stockings, caps, gloves, or the like. - WOULFE'S CHEMICAL APPARATUs for separating Gas from Vapour.-In every process of distillation, the matters sepa- rated and evolved by the application of heat, pass from the dis– tilling vessel to the receiver, either in the form of vapour or of gas, or in both of these forms. If only vapour or steam be the product, it may, by cooling, be condensed into a liquid, in a common receiver of any kind ; as takes place in distilling a spirit from wine, from wash, from ale, or other fermented vinous liquors. If the product be a gaseous fluid alone, that cannot be so condensed, it may prove to be soluble in water in a greater or less proportion; as in the distillation of muriatic acid, nitric acid, ammonia, &c. The matter evolved from the materials in the distilling vessel, may be partly vapour and partly gas. In this case the vapours may, as above, be con- densed, and obtained in a liquid form; and the gas, iſ soluble in water, may, combined there with, be obtained separately in a liquid solution. But the gas that comes over with the vapour may be insoluble in water. In this case, though the vapour, as before, may be condensed, the gas, without an appropriate apparatus, must be lost. To the want of such apparatus may be ascribed the comparatively slow progress that was for many ages made in chemical science. By means of a suitable appa- ratus, the gas, whether soluble or insoluble in water, whether accompanied or not with vapour in coming over, may be col- lected without any loss. When the gas evolved is partly soluble in water and partly insoluble, which sometimes happens, the soluble portion combined with water, the insoluble in the form of gas, and such liquid as may have been produced by the con- densation of vapour, may all three be obtained separately and without any loss. To effect these objects with accuracy and facility remained a desideratum, till Woulfe’s apparatus, so named from its inventor Peter Woulfe, was introduced into the laboratory. Woulfe’s Apparatus, for chemical and pharmaceutical opera- tions, is commonly formed of flint glass; but in large manufac- tories it is sometimes constructed partly of wood and partly of lead or other metals, according to circumstances. The follow- ing are the parts of which it is composed :- - Figure 1. A balloon with two openings; one to receive the beak of a retort, the other for introducing a connecting-tube, to join it to one of Woulfe’s bottles. Fig. 2, one of these bottles with two necks. Fig. 3, another bottle with three necks. Fig. 4, an adaptor, for making a communication between retorts, balloons, bottles, &c. - - Connecting tubes are inserted in the necks of the bottles by means of perforated corks, in which a hole is made to fit the tubes, by employing a round file till the tubes may be firmly fixed in them. The outsides of the corks are made to fit the necks by means of a coarse file. Sometimes the bottles and - | | | | | | - | | |= º | - - V | | N W O U W O U 105.7 DICTION ARY OF MECHANICAL SCIENCE, connecting tubes are joined to each other by corks alone: at other times they are luted. In joining the retort with the bal- loon, or the adaptor with the retort and the bottles, lute alone should be employed, some of which should be pressed in at the place of juncture, that the vessels may be prevented, by means of the interposed lute, from touching each other. The least troublesome method of closing the junctures is, by having the connecting tubes ground as stoppers to fit the necks of the bot- tles; but as they are much exposed to the danger of being broken, they are often dispensed with on account of the cost. Fig. 5, the apparatus with iuted joinings, as arranged for dis- tillation, in which both liquids and gases are produced. e Fig. 6, the apparatus as employed in distillations, in which the products pass over in the form of gas only : not luted, but furnished with refrigeratory vessels. - Fig 7, a connecting tube with a small capillary safety-tube, z, attached to it.—Connecting tubes are generally made of glass, but better, when the products of the process admit of it, of lead tube, or of tubes made of caoutchouc. We shall describe each of these arrangements, and illustrate them by actual examples of operation; and the latter being, in some respects, the simpler of the two, we shall begin with it. When the product of the distillation is merely gaseous, but soluble in water, the earthen or glass retort, r, fig. 6, placed on the naked fire, or in a water-bath, or in a sand-heat, as the case may require, is joined by means of an adaptor a, with the central neck of the bottle b, in one of the side necks of which the safety-tube s is inserted, in such a manner as nearly to touch the bottom. The other neck of this bottle is made to communicate with the two-necked bottle c by means of the con- necting-tube e, bent into the form of the letter n, but with unequal legs, so that the shorter leg reaches only within the neck of the bottle b, while the longer reaches almost to the bot- tom of the two-necked bottle c : this second bottle is combined in like manner with the third bottle d, but it is better that in this communication the connecting-tube should have a little capillary tube, as shewn at 2, fig. 7, for the occasional admission of air when condensation or absorption takes place in the apparatus, or, which is still preferable, the connecting tube may be joined with that kind of safety-tube represented at f, and which goes by the name of its inventor, Welter.—This would always be employed, but for its being very easily broken. Some people, however, prefer, on every occasion, three-necked bottles only, with safety-tubes in each, like the tube s shewn in the bottle b. ' - • In the first bottle b, a sufficient quantity of water is introduced to have the safety-tube s immersed about half an inch ; and in the second and third, that quantity which experience has shewn to be necessary for the absorption of the gas. The safety-tube s is left open, but the capillary tube z, when made use of in the second communication, is luted in such a man- ner that it may be quickly opened; or if Welter’s tube be em- ployed, a little mercury is introduced, to close the lower bend. The second neck of the third bottle, or of the last in the series, when more are employed, may be left open, or slightly closed with a cork. The substances to be operated on are introduced into the receiver through the tubulure, when a tubulated receiver is made use of, and (for the process which we shall hereafter describe) a stopper may be used in place of the bottle with the stop-cock shewn as in the plate, and the joinings may be luted. As soon as the substances in the retort begin to act on each other, the gas that is liberated mixes with the common air in the retort and in the bottle b, and pressing on the water in the descending limb of the connecting-tube e, in the second bottle c, at length makes its passage good into c, and rising in bubbles through the water therein, passes on, in like manner, to the bot- tled. During this transition the gas is absorbed by the water, an affect which - is promoted by the compression both of the gas and the water, also by the minute division and consequent increase of acting surfaces of gas, and by the cooling process carried on at the same time by means of the refrigeratory ves- sels exhibited in the plate, the heat disengaged from the gas in passing to the liquid state, being often such as to cause the Water to boil. But refrigeratory vessels are not always neces- sary. If, by accident or inattention, the heat be urged more than necessary, the gas will be produced in greater quantity 112. - than the connecting tubes can pass: then water will be forced from the bottle b up the safety-tube, till the surface of the water in b is reduced low enough to admit common air. Thus the safety-tube prevents the apparatus from being broken. As the density of the water is increased by absorbing the gas, the pas- sage of which to the next bottle is thereby rendered more diffi- cult, it is better to employ a greater number of bottles than to have the water too high in those made use of. As soon as the development of the gas begins to decrease, the water of the tube of safety descends. This happens either towards the end of the operation, or when the heat is imprudently diminished. If the apparatus be then perfectly cooled, the air in the first bottle is condensed to such a degree, that the atmospheric air enters the tube of safety. But for this tube, the water contained ... in the second bottle would necessarily come over into the first. It would be the same with the third bottle, were not the capil- lary tube of the second communicating tube opened, and the atmospheric air admitted. If the communicating tube be with- Out a capillary tube, the luting of the third bottle must be in- stantly opened, and the bottle itself removed. The height of the water in the safety-tube decreases also at last, in consequence of the second and third bottle becoming cooler, or when from any other cause the absorption of the gas is more rapid than its production. It also frequently happens in the midst of the operation, that the gas, instead of being evolved, is absorbed for a short time by the mass contained in the retort, or that the volume of this mass is otherwise suddenly diminished, which, in like manner, causes the water in the safety tube to fall. The Safety-tube, therefore, not only defends the apparatus from breaking, but also prevents the fluids in the bottles from mixing. It serves moreover, as a mean by which we may judge of the progress of the operation. If, during the progress, a small quantity of gas, unabsorbed, is observed to pass through the open neck of the third bottle, a fourth bottle is immediately to be joined with the third, in the same manner as the third is connected with the second. But on this occasion it should be recollected, that the pressure is increased in the first bottle, and the safety-tube should be consulted. When the operation is finished and the apparatus cooled, the water contained in the bottles will be found impregnated with the developed gas, and more so in the first bottle than in the last. The liquor con- tained in the first bottle is frequently not quite pure, because the small quantity of the body which comes over in the liquid form carries along with it the impurities of the distilled sub- stances ; the other liquors are, however, perfectly pure. If the weight of the water poured into each bottle has been accurately determined, it will be easy, after the operation is finished, to ascertain in the most precise manner, from the increase of weight, not only the whole weight of the gas obtained, but also the de- gree of concentration of the fluids in each bottle. By way of example, we will state the result of a real operation. Preparation of Liquid Ammonia.--To obtain liquid ammonia, formerly called volatile spirit of ammonia, and more commonly spirit of hartshorn, one pound and a half of dry muriate of ammonja, (sal ammoniac,) and four pounds and a half of quick- lime, both in fine powder, were employed in the following man- mer:—Half a pound of lime was put at the bottom of the retort by itself; upon this was thrown a mixture of three and a half pounds of lime and one and a half pound of sal ammoniac: and lastly, the remaining half pound of lime was put in. The retort was placed on a sand bath, and connected with an apparatus of the nature before described. Distillation was now countmenced, and continued, by a heat gradually increased to the ignition of the retort, till the gas ceased to come over. To immerse the tube of safety, three ounces of distilled water were poured into the bottle b, half a pound into c, and half a pound into d. When the apparatus was opened, the first bottle was found to contain 4 ounces 2 drams 40 grains of a foul weak solution of ammo- nia ; the second bottle, 1% ounce 28 grains of strong and pure liquid ammonia; and in the third bottle, 9% ounces 3 drams 16 grains, of an equally pure but weaker solution. Bottle. W Increase. e d 3 ouncess 1 ounce 2 drams 40 grains b 8 Ounces 4 ounces —— 28 grains Ç 8 ounces 1 ounce 7 drams 16 grains ater. —º, ~ —s & g | 9 ounces 7 ounces 2 drams 24 grains 12 N 1058 W O U W R O DICTIONARY OF MECHANICAL SCIENCE. From this it appears, that 13 pound of sal ammoniac afforded 7 ounces 2 drams 24 grains of pure ammoniacal gas, which, dissolved in 19 ounces of water, formed 26 ounces 2 drams 24 grains of liquid ammonia, of which the small portion contained in the first bottle being weak and impure, may be rejected ; that contained in the second bottle was very strong, since two parts water contained one part of ammonia; that in the third portion was also pure, but weaker, the proportion of the ammonia to the water being about 1:5. The residue left in the retort, after the foregoing process, is muriate of ammonia. . The rationale of the process is simply this : sal ammoniac is composed of muriatic acid, and pure ammon ; and the chemical attraction of this acid being greater for lime than for ammonia, it com- bines with the lime, liberating the ammonia, which assumes the gaseous form. Pure ammonia—the base of the gas produced in the manner that has been described, and which, dissolved in water, forms liquid ammonia—is itself a compound of nitrogen (or azote), and 17: 64 of hydrogen by weight, in 100 parts. When the products which come over in distillation are partly liquid and partly gaseous, the apparatus is arranged as in fig. 5. The beak of the retort a is inserted in the tubulated balloon b, which communicates with the three-necked bottle c, by means of the connecting tube f the descending ends of which are of equal length, and enter only within the necks of b and c. In one of the necks of the bottle c is introduced the safety-tube e, made to dip only a little way into the contained liquid, to shut out the air during the distillation. The third neck of c commu- nicates with a second bottle d, by another connecting tube g, one end of which is made long enough to descend almost to the bottom of the bottle d, while the other end only enters the neck of c.—When necessary, a third bottle, or any number, may be joined to the series in the same manner. When the apparatus is thus arranged, the balloon b is left empty, water is introduced into the first bottle c, high enough to cover the orifice of the safety-tube, and also into the second and third bottles, but in greater quantity, to absorb the gas when it passes over. What passes in distillation in the liquid form, collects in the bottom of the balloon ; but the gaseous fluid car- rying with it the common air out of the apparatus, passes on through the connecting-tube f, into the bottle c, and thence through the tube g into the bottle d,—the gas in its passage combining with the water in c and d. When the operation is finished, the liquid product is found in the balloon, and the gas combined with the water in the second bottle—and also in the third, fourth, &c. when the process requires so many. The bot- tle d might communicate directly with the balloon, without the intervention of the bottle c,) in the same manner as it now communicates with c ; but the safety-tube e in the latter is of great use, as it not only serves to indicate the progress of the It is hardly possible to prevent a partial vacuum from being formed in the retort operation, but answers another pupose. towards the close of the distillation, either from accidental cooling, or from the production of gas or vapour beginning to slacken, and its consequent contraction in bulk by cooling. This causes a similar vacuum to be formed in the balloon, to fill which, a strong suction or absorption of the liquid from the first bottle, (which, in the case we allude to, would be d,) would take place through the connecting-tube, causing therein a vacuum, which, in like manner, would produce a similar effect on the one next to it, and so through the whole series of con- nected bottles; and the different products, in the different bot- tles, would thus come to be mixed. But this mischief is obvi- ated by the employment of Woulfe's intermediate bottle c, with the safety-tube e ; for the external air pressing on the small column of water in the safety-tube, and displacing it, enters the bottle, and destroys the vacuum. . This tube answers yet another good end. ated too quickly to be easily passed over by the connecting- tubes, it then presses the surface of the liquid contained in e, which finding a passage up through the tube e, is thereby ex- pelled, and a rupture of the apparatus is prevented. This waste, however, should be as much as possible prevented; for which purpose the upper end of the safety-tube may be intro- duced into a funnel, by being passed through a perforated cork in the pipe thereof. - If the gas be liber- WRECK, the ruins of a ship which has been stranded, or dashed to pieces on a shelf, rock, or lee-shore, by tempestuous weather, or by accident. WRECK is also the name of a soft slippery marine plant that grows on the rocks, having leaves somewhat resembling those of the oak. In many places it is used as manure, but in others. being burnt, the ashes make a kind of soda or potash, found valuable in the manufacture of glass. WREN, SIR CHRI stopher, an eminent English philosopher and mathematician, and one of the most learned and celebrated architects of his age, was born at Knoyle, in Wiltshire, in 1632. In 1660, he invented a method for the construction of solar eclipses; and in the latter part of the same year, he, with ten other gentlemen, formed themselves into a society, to meet weekly, for the improvement of natural and experimental phi- losophy, being the foundation of the Royal Society; of which learned body he was chosen president in 1680. . He died in 1723, at 91 years of age. WRIGHT, EDWARD, an English mathematician, was born in Norfolk about the middle of the 16th century, and died in 1615. He was one of those who laboured to bring the logarithmic tables of Napier and Briggs to perfection, and was the inventor of that division of the meridian on which the mercator's sailing is founded. He was also the author of two works of navigation, the one entitled, “The Correction of certain Errors in Naviga- tion,” published in 1599; and the other entitled “The Haven- finding Art,” of which the date is not mentioned. WRING (To) A MAST, is to bend or strain it out of its natural position, by setting the shrouds up too taught. This phrase is also applied to a capstan, &c. when by too great a strain the component parts of the wood become deranged, and are thereby disunited. WRING Bolts, are bolts used by shipwrights to bend and secure the planks against the timbers, till they are properly fastened by bolts, spikes, and tree-nails. WRING-Staves, bars of wood, used with the preceding article. WRIT, is the king’s precept by which any thing is com- manded touching a suit or action: as the defendant or tenant to be summoned, a distress to be taken, a disseisin to be redress- ed, &c. And these writs are diversely divided; some, in respect of their order or manner of granting, are termed original, and some judicial. WRIT of Inquiry of Damagss, a judicial writ that issues out to the sheriff, upon a judgment by default, in action of the case, covenant, trespass, trover, &c. commanding him to sum- mon a jury to inquire what damages the plaintiff has sustained, occasione praemissiorum ; and when this is returned with the inquisition, the rule for judgment is given upon it; and if nothing is said to the contrary, judgment is thereupon en- tered. WRITER of the Tallies, an officer of the exchequer, being clerk to the auditor of the receipt, who writes upon the tallies the whole of the letters upon the teller's bill. WRITERs to the Siynet. In the Scotch law, attorneys or soli- citors who conduct causes before the courts of Edinburgh. They were so called at first from their having the exclusive privilege of preparing papers requiring the king’s signet. WRONG STAMP. By 37 George III. c. 136, any instrument (except bills of exchange, promissory notes, or other notes, drafts, or orders) liable to stamp duty, whereon shall be impress- ed any stamp of a different denomination, but of an equal or greater value than the stamp required, may be stamped with the proper stamp after the execution, on payment of duty and five pounds penalty, but without any allowance for the wrong stamp. Likewise any such instrument (except as aforesaid) being engrossed without having been first stamped, or having a stamp thereon of less value than required, the same may be stamped after the execution, on payment of the duty and ten pounds penalty only, for each skin thereof; but in case it shall be satisfactorily proved to the commissioners of stamps, that the same hath been so engrossed either by accident or inadvert- ency, or from urgent necessity, or unavoidable circumstances, and without any intention of fraud, the commissioners are authorized to stamp the same within sixty days after the execu- tion, to remit the penalty in part, or wholly, and to indemnify persons so engrossing the same. •º: DICTIONARY OF MECHANICAL SCIENCE. X I P 1059 X. * X 2 or X, the twenty-second letter of our alphabet. In numerals it expresses 10, whence in old Roman manuscripts it is used for denarius; and, as such, seems to be made of two V's placed one over the other. When a dash is added over it, thus X, it signifies ten thousand. XEBEC, a small three-masted vessel, navigated in the Medi- terranean sea, and distinguished from other European vessels by the great projection of the prow and stern beyond the cut- water and stern-post respectively. The sails are in, general similar to those of the polacre, but the hull is different. Being generally equipped as a corsair, it is constructed with a narrow floor, to be more swift in pursuit of the enemy; and of a great breadth, to enable her to carry a considerable force of sail for this purpose, without danger of overturning. As these vessels are usually very low built, their decks are formed with a great convexity from the middle of their breadth towards their sides, in order to carry off the water which falls aboard more readily by their scuppers. But as this convexity would render it difficult to walk thereon at sea, particularly when the vessel rocks by the agitation of the waves, there is a platform of grating extend- ing along the deck from the sides of the vessel towards the middle, whereon the crew may walk dry-footed whilst the water is conveyed through the grating to the scuppers. xebec is equipped for war, she is occasionally navigated in three different methods, according to the force or direction of the wind. Thus, when the wind is fair, and nearly astern, it is usual to extend square sails upon the main-mast, and indeed, frequently on the fore-mast; and as those sails are rarely used in a scant wind, they are of an extraordinary breadth. the wind is unfavourable to the course, and yet continues moderate, the square yards and sails are removed from the masts, and laid by in order to make way for the large lateen yards and sails, which soon after assume their place; but if the foul wind increases to a storm, these latter are also lowered down and displaced, and small lateen yards, with propor- tionable sails, are extended on all the masts. The xebecs, armed as vessels of war by the Algerines, mount from 16 to 24 cannon, and carry from 300 to 450 men, two-thirds of whom are commonly soldiers. The method of working these vessels | When a When is so exceedingly complicated and difficult, that the labour is considerable. XIPHIAS, the Sword Fish, in Natural History, a genus of fishes, of the order apodes. There are three species: The com- mon sword-fish, of the length of twenty feet, which is particularly distinguished by its upper jaw being stretched to a considerable distance beyond the lower, flat above and beneath, but edges at the sides, and of a bony substance, covered by a strong epidermis. It is a fish extremely rapacious, and finds in the above instrument a weapon of attack and destruction, able to procure it the most ample supplies. It first transfixes its prey with this snout, and then devours it. It is found in the Mediterranean, chiefly about Sicily, and is used as food by the Sicilians, who preserve it for a long time by salting it in small pieces.—The broad-finned sword-fish, is found in the northern Atlantic and Indian seas, and is considered as one of the most fatal enemies of the whale tribe. Its strength is so great, that it is said to have pierced with its snout, or sword, the plank of an East Indiaman; and a plank and snout, in attesta- tion of this circumstance, the latter closely driven into the former, are to be seen in the British Museum, having been communicated to Sir Joseph Banks by an East India captain of honour and veracity. When young, this fish is used for food. — The European sword-fish, is known by having its upper jaw lengthened into a hard and sword-shaped blade; and its dorsal fin long, and lowest in the middle. These fish are of steel-blue colour, and measure from fifteen to twenty feet in length. They are found in most of the European seas. By the ancient Romans, sword-fish were highly esteemed as food; and were killed with harpoons by persons stationed in boats for that purpose. They were not only eaten fresh, but cut into pieces and salted. In several places near the Medi- terranean, the fins are salted, and sold under the name of callo. XI PHIAs, in Astronomy, the Dorado, or Sword Fish. See CoNSTELLATION. XIPH1As is also a term used to express a fiery meteor, that is said to appear in the form of a sword; and which is some- times called A contias, from its resemblance to a serpent thus denominated in Calabria and Italy, where it is well known. Y. Y A R. Y, the twenty-third letter of our alphabet. Y is a numeral, signifying 150, or, according to Baronius, 159; and with a dash at top, as Y, it signifies 150,000. - YACHT, a vessel of state, usually employed to convey princes, ambassadors, or other great personages, from one kingdom to another. As the principal design of a yacht is to accommodate the passengers, it is usually fitted with a variety of convenient apartments, with suitable furniture. The royal yachts are commonly rigged as ketches, except the principal one, which is equipped as a ship. They are commanded by post-captains of the navy. The smaller yachts, which are rigged as sloops, are destined for the use of the commissioners of the navy, &c. Private pleasure boats, when sufficiently large for a sea voyage, are also termed yachts. - YANOLITE. Axinite. . YARD, a long piece of timber suspended upon the masts of a vessel, to extend the sail to the wind. They are either square, lateen, or lug-sail; the first are suspended across the mast at right angles, and the two latter obliquely. The square yards are of a cylindrical form, tapering from the middle, which is t Y A. R. called the slings, towards the extremities, which are termed the yard-arms, and the distance between the slings and the yard-arms on each side, is by the artificers divided into quar- ters, which are distinguished into the first, second, and third quarters, and yard-arms. The middle quarters are formed into eight squares, and each of the end parts is figured like the frustrum of a cone. All the yards of a ship are square, except that of the mizzen. The proportions for the length of yards, according to the different classes of ships in the British navy, are as follow :-": ſ 560 : I 00 Guns. 559 : 90, 80 1000 : gun deck: ;....< 379 \-Main yard ......... 70 576 : 60 575 : 50 561 : 44 880 : 100,90, 80, § {fore yard … } all the rest. To apply this rule to practice, suppose the gun-deck 144 feet; the proportion for this length is, as 1000 to 575, so is 144 to 83, 1000 : main yard ::. ...} 1060 Y A. R. Y A. R. DICTIONARY OF MECHANICAL SCIENCE. which will be the length of the the main yard in feet, and so cf all the rest. . 100, 90, 80 820 : R S0, 44 1000 : main yard : : . . . . ; 847 : X mizzen yard . . . . . . . . ) 70 $40 $ 24 tº 726 : e YT -. $ 24 1000 : main yard : : . . . º 720 : {main top sail yard . . . ° N all the rest. 710 : R 70 1000 : fore yard : . . . . . . 726 : X forc top sail yard . . . . ( 24 7 l 5 : $ all the rest. 1000 : main top sail yard :: 690 : main top sail yard .... all the rates. (MS - psy 1000 : fore top sail yard: 3 . . {fore top gallant yard . . } º the rest. 1000 : fore top sail yard : º ſ: . {mizzen top gallant yard; ... the rest. Cross-jack and sprit-sail yards equal to the fore-top sail-yard. Sprit-sail top-sail yard equal to the fore-top-gallant yard. The diameters of the yards are in the following proportions to their length:—The main and fore yards, five-sevenths of an inch to a yard. The top-sail cross jack and sprit-sail yards, nine-four- teenths of an inch to one yard. The top-gallant, mizzen-top- sail, and sprit-sail top-sail yards, eight-thirteenths of an inch to one yard. The mizzen-yard, five-ninths of an inch to one yard. All studding-sails, booms, and yards, half an inch to one yard in length. The large lateen yards are usually composed of several pieces fastened together by wooldings, which also serve as steps, whereby the sailors climb to the peek or upper extre- mity, in order to furl or cast loose the sail. The mizzen yard of a ship, the main yard of a bilander, and the yards of a lug- ger, though they are not, strictly speaking, lateen sails, are nevertheless hung obliquely on the mast, and the slings are nearer the fore-end than the aftmost end or peek. YARD Tackles, strong tackles suspended from the main and fore-yards of a ship of war, &c. whereby, with the assistance of the stay-tackles, the boats and other weighty matters are hoisted in and out. - To Brace the YARDs, to traverse them about the masts so as to form greater or lesser angles with the ship's length. See the article BRACE. \ YARD Arm, is that half of the yard that is on either side of the mast, when it lies athwart the ship. Yard-Arm and Yard-Arm, a phrase applied to two ships, when they are so near, that their yard-arms nearly touch each other. - g YARD-Arm Pieces, pieces of timber kept in readiness to repair the yard-arms in the event of their being carried away or broken. - - YARDs, also denote places belonging to the navy, where the ships of war, &c. are laid up in harbour. There are belonging to his majesty’s navy, six great yards, viz. Chatham, Deptford, Woolwich, Portsmouth, Sheerness, and Plymouth; these yards are fitted with several docks, wharfs, launches, and graving places, for the building, repairing, and cleaning of his majesty’s ships; and therein are lodged great quantities of timber, masts, planks, anchors, and other materials: there are also convenient store-houses in each yard, in which are laid up vast quantities of cables, rigging, sails, blocks, and all other sorts of stores, needful for the royal navy. YARD, an English measure of length, and used also by several other European nations. The English yard contains 3 feet, and is equal to 4-5ths of the English ell, to 7-9ths of the Paris ell, to 4-3ds of the Flemish ell, to 56-5ths of the Spanish vasa or yard. YARN, wool or flax spun into thread, of which cloth is made ; or, in a nautical sense, it signifies one of the threads of which ropes are composed. The thread, or twisted line of hemp, is the first and principal part of a rope. A number of these are twisted together to form a strand, in proportion to the size of the rope whereof the strand makes a part. Three strands are then twisted into one another, which completes the process of ordinary rope-making. But cables, hawsers, and other ground tackling, are composed of three strands, each of which is formed by three lesser ones. See CABLE, Yarn is ordered after the following manner: After it has been spun upon spindles, spools, or the like, they wind it upon reels which are hardly two feet in length, and have but two contrary cross bars, being the best and the least liable to ravelling. In reeling of yarn, the better to keep it from fine ravelling, you must, as it is reeled, with a by-band of big twist, divide the slipping or skein into several leys, allowing to every ley eighty threads, and twenty leys to every slipping, if the yarn is very fine, otherwise less of both kinds. The yarn being spun, reeled, and in the slipping, the next thing is to scour it. In order to fetch out the spots, it should be laid in lukewarm water for three or four days, each day shifting it once, wringing it, out and laying it out in another water of the same nature; then carry it to a well or brook, and rinse it till nothing comes from it but pure clear water; that done, take a bucking-tub, and cover the bottom thereof with very fine ashen ashes; and then having opened and spread the slippings, covering them with ashes as before, and thus laying one upon another till all the yarn be put in, afterwards cover the uppermost yarn with a bucking-cloth, and in proportion to the bigness of the tub lay therein a peck or two more of ashes: this done, pour upon the uppermost cloth a great deal of warm water till the tub can receive no more, and let it stand so all night. Next morning you are to set a kettle of clean water on the fire, and when it is warm pull out the spiggot of the bucking-tub, to let the water run out of it into another clean vessel. As the bucking-tub wastes, fill it up again with the warm water on the fire; and as the water on the fire wastes, so likewise fill that up with the ley that comes from the bucking-tub, ever observing to make the ley hotter and hotter till it boils; then you must, as before, ply it with the boiling ley, at least four hours together, which is called the driving of a breek of yarn. Of yarn thus prepared, are made the sails, cloths, &c. used in vessels. .. YARN-Mill. This machine may be worked by water, or as a horse-mill, or in any other way, and is made and used in the following manner. There is a cylinder marked A, plate Watch, &c. fig. 1, three feet diameter, and ten inches broad, made of dry wood or metal, turned true, and covered on its circumference with a smooth leather, upon which are placed the rollers marked D, covered with leather, and supported in their situations by the slits in the covered piece of wood, marked K, in which the iron axes of the rollers turn, but suffers them to press on the wheel marked A. There must be another piece similar to the above, to support the other end of the rollers. These rollers are of different weights. The upper roller marked D I is two stone, the rest decreasing to the last, which is only two pounds weight and one half. There is an iron fluted roller marked F, furnished with a toothed wheel at each end, and a wood one, marked G, covered with cloth, and over it a smooth leather. There is an assisting roller, marked H, of fluted iron. These rollers are supported by their axes turning in the slit, marked 2, of the piece of wood, marked M, fig. 3, which is here separa- ted from the end of the frame marked S, to shew the rollers and wheel-work. The rollers marked G and F are squeezed together by means of the lever marked p, and its weight marked w, fig. 3. The roller marked H is pressed to the mark G, by its axis acting upon the inclined plane marked ac, fig. 3. There is a rubbing roller covered with woollen cloth, and on its axis is a small wheel marked I, driven by the wheel marked S. This roller rests upon the roller marked G, and by its motion pre- vents any dirt or fibres from adhering to it. There is a cloth, marked N, revolving over two rollers marked O, O, which has motion given it from the wheel marked C, by means of another wheel marked P, This cloth moves at the same rate as the surface of the wheel marked A. There is a supporter marked Y, of the axis of the wheel marked O, P, but is removed, in order to shew them; it is fixed by its tenons in the mortises, marked Z, Z. The roller marked B is kept in action by its endeavour to slip down the inclined plane at the top of the piece marked Y, thereby pressing against the revolving cylin- der; and another piece similar to this, must be understood to support the other end of the roller's axis. By the side of this revolving cloth is a table placed, of the same length and breadth as the cloth is, to which belong two smooth cloths or leathers, of the same size as the table. The machine being thus prepared, the attendant or workman must take a quantity of hemp, tow, Y E. A. Y E A § {}61 DICTIONARY of MECHANICAL scIENCE. flax, or wool, more or less, according to the fineness of the thread to be made, and lay or spread it evenly upon one of the smooth cloths on the table, then place it on the revolving-wheel marked N, motion being communicated to the roller marked T, by wheel-work as usual, from a water, horse, or other kind of mill, which wheel-work is communicated to the wheel marked J., on whose axis is a nut, which turns the wheel marked C ; and thereby the cylinder marked A moves, and with it all the rollers; by which motion the hemp, tow, flax, or wool is drawn forward. The cloth turns down, but the hemp, tow, flax, or wool, go upon the cylinder marked A, under the roller marked B, and so forward under the rollers marked D, then falls in between the rollers marked G, F, turns under the roller marked G, and over the roller marked H, which, as it gives the rollers hold of the hemp, tow, flax, or wool, in two places, enables them to draw forward the long fibres thereof, though many of them are to draw from under the marks 4 or 5 of the pressing- rollers marked D, it then falls into a canister marked R, and as by the wheel-work the rollers marked F, G, H, move three times faster than the cloth and cylinder, the sliver must be three times longer than when presented. By the time this is drawing, the other cloth is filled with hemp, tow, flax, or wool, as before, and laid upon the revolving roller, laying the hemp, tow, flax, or wool, over the end of the other which goes forward as before, and thus a continued sliver is produced as long as the machine continues its motion. But in order that this sliver may come out of the canister marked R, without entanglement, it must pass through an instrument marked 5, fig. 3, placed over the rollers marked F, G, its open side marked T, to the cylinder at mark 4, supported by its ends marked V, V, in the slit marked W, of the before...described pieces marked K. The aperture X is so small as to press the fibres close to each other in their passage through it previous to their passing the rollers, by which means they remain pressed side by side in the sliver, and will not entangle. These thick slivers are drawn smaller by a similar process, and in the same manner are used for cottons: but the machines for drawing are all of the same structure as the above, except that they have no revolving cloth. The sliver is applied to the cylinder under the roller marked B, which draws it forward under all the rollers as before described, drawing it out, or lengthening it, every fresh ma- chine through which it presses, till it be small enough for the spinning machine. It must be remarked, that the cylinders are made less in diameter, according to the different smallness of the sliver intended to be drawn upon them at the first ; whilst the sliver is at its greatest thickness, the cylinder is required to be three feet diameter as above described, the next rather less, and so on to the last, which is only two feet. The aperture of the bottom of the contractor belonging to each machine is also made one-third part smaller than another in succession, from the greatest to the smallest cylinder; as also the drawing rollers marked. F, G, H, are furthest from the pressing-roller marked D, in the longest cylinder, and nearest at the smaller cylinder. At the largest cylinder the distance is about mine inches, and the smallest about four inches; but their distance cannot in all cases be fixed, as it depends on the different lengths of the slivers of the hemp, tow, flax, or wool ; long ones requiring the distances mentioned, and short ones requiring the distances much shorter than is here specified. The following several letters or marks are in the machine figured 2. The spinning machine, as to its drawing principle, is the same as the drawing machine. The slivers are presented to it in canisters marked A, and drawn over a cylinder marked B covered with rollers marked D. The fibres which are to form the thread are drawn from the cylinder by the rollers marked C, the under roller of which is made of fluted iron, the other of wood, covered with leather; they move six or eight times faster than the cylinder marked B are enabled to draw the hemp, tow, flax, or wool, forward from under the pressing- rollers marked D, by being squeezed together with the weights and crooks marked a, a, locked to the small part of the rollers marked C. There is a belt of smooth cloth marked E, moving on two rollers, which are turned by the wheel marked F, on the axis of the fluted roller; at the opposite end of which, as at the mark G, is a mut, which turns the wheel marked H, on whose axis is another nut, turning the wheel marked I, and thereby the cylinder marked B, with all its rollers. These rollers move in curved pieces of wooden metal, marked K, which, to prevent confusion, are not represented in their places; they have slits in them in which the rollers’ axes are guided. but so deep as at all times to suffer the rollers to press upon the cylinder. These rollers are covered with cloth and leather. The top roller is about ten pounds weight, decreasing to the sixth roller, which is only about one pound weight: the yarn is turned by the spindles marked L, and rubbed over the wet cloth -belt if spinning Hinen yarn, but if spinning worsted yarn the belt must be removed, that it may not touch it as it passes to the Spool, which it coils round as fast as the rollers let it out. The spindles marked C are turned by a bolt from the wheel marked M, which derives its motion from the mill, and by a wheel on its axis communicates it to the roller under the mark C by the wheel marked F, and so to the rest, as above described. The hemp, tow, flax, or wool, is twined in the same manner as cotton 112. article BoA.T. is by mills. YAW, the movement by which a ship deviates from the line of her course towards the right or left in steering. Y AWL, a boat usually rowed with four or six oars. See the YEAR, in Astronomy and Chronology, the portion of time occupied by the sun in passing over the twelve signs of the zodiac, and in which is comprehended the several changes of the seasons. The mean solar year, according to the observa- tions of the best modern astronomers, contains 365 days, 5 hours, 48 minutes, 48 seconds; the quantity assumed by the authors of the Gregorian calendar, is 365 days, 5 hours, 49 minutes; but in the civil or popular account the year contains 365 days, 6 hours, or rather 365 days for three years in succession, and every fourth year 366 days. See Bissex.TILe. The vicissitude of seasons seems to have given occasion to the first institution of the year. Man, naturally curious to know the cause of their diversity, soon conjectured that it depended upon the motion of the sun, and therefore gave the name year to the space of time in which that luminary seemed to perform his whole course, by returning again to the same point of its orbit. According to the accuracy of their observa- tions, the year of some nations was more perfect than that of others, but none of them quite exact, nor whose parts did not shift with regard to the parts of the sun's course. According to Herodotus, it was the Egyptians who first formed the year, making it to consist of 360 days, which they subdi- vided into 12 months, of 30 days each. Mercury Trismegistus added five days more to the account; and which form of the year, Thales is said to have instituted amongst the Greeks; and hence, with successive improvements, it has been handed down to the moderns. The Solar Ye AR, is either astronomical or civil. The Astronomical Solar Ye AR, is that which is precisely determined by astronomical observations, and is of two kinds, tropical, and sidereal or astral. . Tropical or Natural YEAR, is the time which the sun, or rather the earth, employs in passing through the 12 signs of the zodiac, and which, as stated above, contains 365 days, 5 hours, 48 minutes, 48 seconds, which is the only natural year, because it always keeps the same seasons in the same months. Sidereal Ye AR, or Astral Year, is the space of time the sun takes in passing from any fixed star, till his return to it again. This consists of 365 days, 6 hours, 9 minutes, 11 seconds, being 20 minutes, 29 seconds longer than the true solar year. Anomalistic Year, is the interval which is occupied by the sun in passing from apogee to apogee, or from perigee to peri- gee : it is greater than the sidereal year by the time required to describe the annual progression of the apogee. The length of the anomalistic year is 365 days, 6 hours, 14 minutes, I second. Lunar Year, is the space of 12 lunar months. Hence, from the two kinds of synodical lunar months, there arise two kinds of lunar years; the one astronomical, the other civil. Lunar Astronomical YEAR, consists of 12 lunar synodical months; and therefore contains 354 days, 8 hours, 48 minutes, 38 seconds, and is therefore 10 days, 21 hours, 0 minutes, 10 seconds, shorter than the solar year. A difference which is the foundation of the epact. 12 O 1062 Y E A Y E A DICTIONARY OF MECHANICAL SCIENCE. Lunar Civil Year, is either the common or embolismic. The Common Lunar YEAR, consists of 12 lunar civil months; and therefore contains 354 days. And - The Embolismic, or Intercalary lunar Year, consists of 13 lunar civil months, and therefore contains 384 days. Thus far we have considered years and months with regard to astronomical principles, upon which the division is founded. By this, the various forms of civil years that have formerly obtained, or that do still obtain, in divers nations, are to be examined. Civil Year, is that form of the year which every nation has contrived or adopted for computing their time by. Or the civil is the tropical year, considered as only consisting of a certain number of whole days: the odd hours and minutes being set aside, to render the computation of time, in the common occa- sions of life, more easy. As the tropical year is 365 days, 5 hours, 49 minutes, or almost 365 days, 6 hours, which is 365 days and a quarter; therefore, if the civil year be made 365 days, every fourth year it must be 366 days, to keep nearly to the course of the sun. And hence the civil year is either com- mon or bissextile. Common Civil Year, is that consisting of 365 days; having seven months of 31 days each, four of 30 days, and one of 28 days; as indicated by the following well-known memorial VerSe:— Thirty days hath September, April, June, and November; February twenty-eight alone, And all the rest have thirty-one. Bisseatile, or Leap Year, contains 366 days, having one day extraordinary, called the intercalary, or bissextile day, and takes place every fourth year. This additional day to every fourth year was first introduced by Julius Caesar, who, to make the civil years keep pace with the tropical ones, contrived that the six hours which the latter exceeded the former should Imake one day in four years, and be added between the 24th and 23d of February, which was their 6th of the calends of March; and as they then counted this day twice over, or had bis sea to calendas, hence the year itself came to be called bis seatus, and bisseatile. However, among us, the intercalary day is not introduced by counting the 23d of February twice over, but by adding a day at the end of that month, which therefore in that year contains 29 days. A farther reformation was made in the civil year by pope Gregory. The civil or legal year, in England, formerly commenced on the day of the Annunciation, or 25th of March ; though the historical year began on the day of the circumcision, or 1st of January ; on which day the German and Italian year also begins. The part of the year between these two terms was usually expressed both ways; as 1745.6, or 1743. But by the act for altering the style, the civil year now commences with the 1st of January. -- - Ancient Roman YEAR. This was the lunar year, which, as first settled by Romulus, contained only ten months, of unequal numbers of days, in the following order, viz.:-March 31 ; April 30; May 31; June 30; Quintilis 31; Sextilis 30; Septem- ber 30; October 31; November 30; December 30; in all 304 days; which came short of the true lunar year by 50 days, and of the solar by 61 days. Hence, the beginning of Romulus's year was vague, and unfixed to any precise season; to remove which inconvenience, that prince ordered so many days to be added yearly as would make the state of the heavens correspond to the first month, without calling them by the name of any month. Numa Pompilius corrected this irregular constitution of the year, composing two new months, January and February, of the days that were to be added to the former year. Thus Numa's year consisted of 12 months, of different days, as follow, viz.:- January 29; - - February 28; - - March 31 ; April 29; - - May 31; - - June 29; Quintilis 31; - - Sextilis 29; - - September 29; October 31; - - November 29; - - December 29; in all 355 days; therefore exceeding the quantity of a lunar civil year by one day; that of a lunar astronomical year by 15 hours, 11 minutes, 22 seconds; but falling short of the com mon solar year by 10 days, so that its beginning was still vague and unfixed. Numa, however, desiring to have it begin at the winter solstice, ordered 22 days to be intercalated in February every second year, 23 every fourth, 22 every sixth, and 23 every eighth year. But this rule failing to keep matters even, recourse was had to a new way of intercalating ; and instead of 23 days every eighth year, only 15 were to be added. The care of the whole was committed to the pontifex maximus; who, however, neglecting the trust, let things run to great con- fusion. And thus the Roman year stood till Julius Caesar reformed it. - The Ancient Egyptian YEAR, called also the year of Nabonas- sar on account of the epocha of Nabonassar, is the solar year of 365 days, divided into 12 months of 30 days each, besides five intercalary days added at the end. The mames, &c. of the months are as follows:—l. Troth. 2. Paophi. 3. Athyr. 4. Chojac. 5. Tybi. 6. Mecheir. 7. Phamen oth. 8. Pharmu- thi. 9. Pachon. 10. Paumi. 11. Epiphis. 12. Mesori; beside the 7) Puspat strayopswat. < The Ancient Greek YEAR, was lunar ; consisting of 12 months, which at first had 30 days apiece, then alternately 30 and 29 days, compared from the first appearance of the new moon; with the addition of an embolismic month of 30 days every 3d, 5th, 8th, 11th, 14th, 16th, and 19th year of a cycle of 19 years; in order to keep the new and full moons to the same terms or seasons of the year. Their year commenced with that new moon, the full moon of which comes next after the summer solstice. The order, &c. of their months was thus:– 1. ‘Ekaropſ3awv, containing 29 days. 2. Mmraysirvuov, 30. 3. Bomépopuwy, 29. 4. Masparrmptov, 30. 5. IIvaveil/wy 29. 6. IIoostöswv, 30. 7. Tapu)\wy, 29. 8. A80sgmpwv, 30. 9. EAapm30- Aww, 30. 10. Mavvywy, 30. 11. 6apym\wy, 29. 12. Xkupogo- putov, 30. The Ancient Jewish Yea R, is a lunar year, consisting com- monly of 11 months, which alternately contain 30 and 29 days. It was made to agree with the solar year, either by the adding of ll, and sometimes 12 days, at the end of the year, or by an embolistic month. The names and quantities of the months stand thus:–1. Nisan, or Abib, 30 days. 2. Jiar, or Zius, 29. 3. Siban, or Siwan, 30. 4. Thammuz, or Tammuz, 29. 5. Ab, 30. 6. Elul, 29. 7. Tisri, or Ethanim, 30. 8. Marches van, or, Bull, 29. 9. Cisleu, 30. 10. Tebeth, 29. 1 1. Sabat, or Sche- beth, 30. 12. Adar, in the embolismic year, 30. Adar, in the common year, was but 29. Note, in the defective year, Cisleu was only 29 days; and in the redundant year, Marches van WaS 30. The Persian Ye AR, is a solar year of about 365 days, consist- ing of 12 months of 30 days each, with five intercalary days added at the end. The Arabic, Mahometam, and Turkish YEAR, called also the year of the Hegira, is a lunar year, equal to 354 days, 8 hours, and 48 minutes, and consists of 12 months, which contain alter- nately 30 and 29 days. - - The Hindoo YEAR differs from all these, and is indeed dif- ferent in different provinces of India. The best account that we have of it is by Mr. Cavendish, in the Philosophical Trans- actions of the Royal Society for the year 1792. Year and Day, is a time that determines a right in many cases; and in some works an usurpation, and in others a pre- scription; as in case of an estray, if the owner, proclamation being made, challenges it not within the time, it is forfeited. So is the year and day given in case of appeal; in case of descent after entry or claim, if no claim upon a fine or writ of right at the common law; so of a villain remaining in ancient demesne ; of a man sore bruised or wounded ; of protections ; essoins in respect of the king's service; of a wreck; and divers other CaS6S. YEARDAY AND WAste, is a part of the king’s prerogative, whereby he challenges the profits of their lands and tenements for a year and a day, that are attainted of petty treason or felony, whoever is lord of the manor where the lands or tenements belong ; and not only so, but in the end may waste the tene- ments, destroy the houses, root up the woods, gardens, and pasture, and plough up the meadows, except the lord of the fee. agrees with him for redemption of such waste, afterward restor- ing it to the lord of the fee. Y E O Y T T. 1063 DICTIONARY OF MECHANIC AL SCIENCE. YEARS, E3TAte for. Tenant for term of 'years, is where a man lets lands or tenements to another, for a certain term of years agreed upon between the lessor and lessee ; and when the lessee enters by force of the lease, then he is tenant for term of years. YEAST, is the barm or froth which rises in beer, and other malt liquors, during a state of fermentation. When thrown up by one quantity of malt or vinous liquid, it may be preserved, to be put into another at a future period, on which it will exert a similar fermentative action. Yeast is likewise used in the making of bread, which without such an addition would be heavy and unwholesome. YELLOW, NAPLes, a fine pigment, so called from the city in which it was long prepared, * YEOMAN, is defined to be one that has fee land of 40s. a year; who was thereby heretofore qualified to serve on juries, and can yet vote for knights of the shire, and do any other act where the law requires one that is probus et legalis homo. YeoMAN, an inferior officer under the boatswain, gunner, or carpenter of a ship of war, and usually charged with the Stow- age, account, and distribution of their respective stores. YeoMAN of the Guard, one belonging to a sort of foot guards, who attend at the palace. The yeomen were uniformly required to be six feet high. They are in number 100 on constant duty, and 70 off duty. The one half carry arquebuses, and the other pertuisans. Their attendance is confined to the sovereign's person, both at home and abroad. They are clad after the manner of king Henry VIII. YOKE, in Agriculture, a frame of wood fitted over the necks of oxen, whereby they are coupled together, and harnessed to the plough. Yoke, a small board which crosses the upper end of a boat's rudder at right angles, and having two lines extending from its opposite extremities to the stern-sheets of the boat, whereby she is steered as with a tiller. YOLK, is an animal soap, the natural defence of the wool of sheep. In washing sheep, the use of water containing the car- bonate of lime should be avoided ; for this substance decom- poses the yolk of the wool, and wool often washed in calcare- ous water becomes rough and more brittle. The finest wool, such as that of the Spanish and Saxon sheep, is most abundant in yolk. M. Vauquelin has analyzed several different species of yolk, and has found the principal part of all of them a soap, with a basis of potassa (i. e. a compound of oily matter and potassa,) with a little oily matter in excess. Yolk is also the yellow substance found in the middle of an egg, by which the chicken is supported before its exclusion from the shell; and even afterwards, a portion being received into its belly, it is its only source of nourishment for a consi- derable time. YOUNKER, a general name for a stripling in the service. YTTRIA. This is a new earth, discovered in 1794, by Prof. Gadolin, in a stone from Ytterby in Sweden. Yttria is per- fectly white when not contaminated with oxide of maganese, from which it is not easily freed. Its specific gravity is 4.842. It has neither taste nor smell. Z. Z E R. Z, the twenty-fourth and last letter of our alphabet. In ab- breviations this letter formerly stood as a mark for several sorts of weights ; sometimes it signified an ounce and a half, and very frequently it stood for half an ounce; sometimes for the eighth part of an ounce, or a dram troy weight; and has in ear- lier times been used to express the third part of an ounce, or eight scruples. ZZ were used by some of the ancient physi- cians to express myrrh, and at present they are often used to signify zinziber or ginger. : ZAFFRE, is the oxyde of cobalt, employed for painting pot- tery-ware and cobalt of blue colour. ZEA MAIze, or Indian Corn, in Botany, a genus of the mo- noecia triandria class and order, Natural order of gramina or grasses. Essential character: males in distinct spikes; calyx, glume two-flowered, awnless: corolla, glume two-flowed : awn- less ; female, calyx glume one-flowered, two-valved; corolla, glume four-valved; style one, filiform pendulous; seeds soli- tary, immersed in an oblong receptacle. There is but one spe- cies, viz. Z. mays, Indian corn, or maize and several varieties. See MAIze or MAISE. ZENITH, an Arabic word, used in astronomy to denote the vertical point of the heavens, or that point directly over our heads. The zenith is called the pole of the horizon, being 90° distant from every point of that circle. ZEN ITH Distance, the arc intercepted between any celestial object and the zenith, being the same as the co-altitude of an object. - ZEOLITE. This stone was first described by Cronstedt in the Stockholm Transactions for 1756. It is sometimes found amorphous and crystallized. The primitive form of its crystal is a rectangular prism, whose bases are squares. The most common variety is a long four-sided prism terminated by low four-sided pyramids. - ZERO. The commencement of a scale of the thermometer marked 0. In Fahrenheit's thermometer, zero is 329 below freezing point. In Reaumur's thermometer, and in the centi- grade thermometer, zero coincides with the freezing point of Water. Z I N ZETETIC Method, an old term for what we now call analytic method. ZIMOME. If the gluten of wheat be treated with alcohol, it is reduced by the loss of water and gliadine to one-third of its bulk, which consists of zimome. Zimome is a shapeless mass, rough, and destitute of cohesion. It is heavier than water. It is soluble in vinegar and the mineral acids, at a boiling tem- perature. Zimome is found in various vegetables. ZINC, in Chemistry and Mineralogy, a metal unknown to the ancients, though they were acquainted with calamine, one of its ores, and the effect which this had in converting copper into brass. Zinc has usually been ranked among those metals which, from their imperfect ductility and malleability, were long denominated semi-metals. It was known, that by uniform pressure zinc might be extended into thin plates, and, more lately, it has been discovered, that, at a certain temperature, it has so much malleability and ductility that it can be lamellated and drawn into wire. Zinc is of a white colour with a shade of blue ; in a fresh frac- ture it is possessed of considerable lustre. It is hard, and not easily cut with a knife. The specific gravity is nearly 7-2. The ores of zinc are calamine and blende. Calamine is an oxide, frequently with a portion of carbonic acid : blende is a sulphu- ret, containing also some iron and other extraneous matters. Zinc is melted by a moderate heat, and the fused mass, on cool- ing, forms regular crystals. Though scarcely altered by expo- sure to the air at a low temperature, yet it is rapidly oxydized by one amounting to ignition. When kept in a degree of heat barely sufficient for its fusion, zinc becomes covered with a grey oxide. But when thrown into a crucible or deep earthen pot, heated to whiteness, it suddenly inflames, burns with a beauti- ful white flame, and a white and light oxide sublimes, having considerable resemblance to carded wool. It is brittle, and has not been applied to any use. Zinc may be combined with mer- cury, either by triturating the metal together, or dropping mer- cury into melted zinc. This amalgam is used to rub on elec- trical machines, in order to excite electricity. Zinc combines readily with copper, and forms one of the most useful of all the . . .1064 Z O. D Z O D DICTIONARY OF MECHANICAL SCIENCE. metallic alloys. The metals are usually combined together by stratifying plates of copper, and native oxide of zinc combined with carbonic acid, called calamine, and applying heat. When the zinc does not exceed a fourth part of the copper, the alloy is known by the name of brass. It is of a beautiful yel- low colour, more fusible than copper, and not so apt to tarnish. It is malleable, and so ductile that it may be drawn out into wire. Its density is greater than the mean. It ought to be by calculation 7-6, but it actually is 84 nearly, so that its density is increased by about one-tenth. When the alloy contains three parts of zinc and four of copper, it assumes a colour nearly the same with gold, but it is not so malleable as brass. It is then called pinchbeck, prince's metal, or Prince Rupert's mctal. Brass was known and very much valued by the ancients. They used an ore of zinc to form it, which they called cadmia. To brass they gave the name of orichalcum. Their as was cop- per, or rather bronze. - - ZIR CON, in Mineralogy, the name of a genus containing two species, viz. hyacinth and zircon. It is found commonly in roundish angular pieces, which have almost always rounded angles and edges. 'Specific gravity about 4:6. The constitu- ent parts are, according to Klaproth, Zirconia, s e º 'º e º e up G e º tº it e º e º 'º e º e º e º e e º a c e º ºs e tº 69:0 Silica, . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26'5 Oxide of iron, . . . . . . . . . tº º ºs º ºs º ºr e º ſº dº º ºs º ºs e º e. e. 0-5 Loss, tº e º e º e s tº e º ſº * e s s e º z e a e o sº a tº s 2 tº 6 & © * - 4” () 100-0 ZIRCONIA, was first discovered in the jargon of Ceylon, by Klaproth, in 1789, and it has since been found in the jacinth. Zircon is a fine white powder, without taste or smell, but some- times harsh to the touch. It is insoluble in water; yet if slowly dried, it coalesces into a semi-transparent yellowish mass, like gum-arabic, which retains one-third its weight of water. It unites with all acids. It is insoluble in pure alkalies ; but the alkaline carbonates dissolve it. Heated with the blow-pipe, it does not melt, but emits a yellowish phosphoric light. There is the same evidence for believing that zirconia is a compound of a metal and oxygen, as that afforded by the action of potas- siurg on the other earths. ZIZANIA, a genus of plants of the class monoecia, order hexandria, and in the natural system arranged under the fourth order gramina. ZODIAC, in Astronomy, an imaginary ring or broad circle in the heavens, in form of a belt or girdle, within which the planets all make their excursions. In the very middle of it runs the ecliptic, or path of the sun in his annual course; and its breadth, comprehending the deviations or latitudes of the earlier known planets, is by some authors accounted 16, some 18, and others 20 degrees. The zodiac cutting the equator obliquely, makes with it the same angle as the ecliptic, which is its mid- dle line, which angle, continually varying, is now nearly equal to 23° 28′ ; which is called the obliquity of the ecliptic, and constantly varies between certain limits which it can never exceed. The zodiac is divided into 12 equal parts of 30 degrees each, called the signs of the zodiac, being so named from the con- stellations which anciently occupied them. But the stars hav- ing a motion from west to east, those constellations do not now correspond to their proper signs; from whence arises what is called the precession of the equinoxes. And therefore when a star is said to be in such a sign of the zodiac, it is not to be understood of that constellation, but only of that dodecatemory or 12th part of it. - g It is a curious fact, that the solar division of the Indian zodiac is the same in substance with that of the Greeks, and yet that it has not been borrowed either from the Greeks or the Arabians. The identity, or at least striking similarity, of the division is univer- Sally known ; and Montucla has endeavoured to prove that the Bramins received it from the Arabs. very generally admitted; but in the second volume of the Asia- tic Researches, Sir William Jones asserts that neither of these nations borrowed that division from the other ; that it has been known among the Hindoos from time immemorial ; and that it was probably invented by the first progenitors of that race, whom he considers as the most ancient of mankind, before their His opinion has been Thoth. dispersion. The Greek zodiac originally contained only eleven signs; the Scorpion in their zodiac occupying the place of two. The Zodiacs of Esmesh and Dendera.—These monuments represent the actual state of the heavens at the solstice period, i.e. the year 2782 B. c., or the year 1322 B.C., or the year 138 A. c. the solstice period being 1460 years. - Received chronology assigns a period of 5824 years from the Creation to 1820 of the Christian aera. The Samaritan text of the scriptures makes the world to have been created 6065; the Septuagint 7210 years; and it is 7508 years since the crea- tion, according to the testimony of Josephus. The mean of all these dates will be 6651 years, and which is perhaps not far from truth. If we adopt the chronology of the LXX. the period of 7210, from the creation to the year 1820 of our aera, Inay be divided thus:—2262 years from the creation to the deluge, and 3128 years from the deluge to the birth of our Saviour. With this system of chronology we shall be able to explain consist- ently the age of these zodiacs. In the year 4189 of the Julian period, Cambyses conquered Egypt; at the end of 39 years the people revolted; in two years after they were compelled to submit again to their tyrants. |Under the reign of Artaxerxes, about 21 years after their first emancipation, they again took arrns, and drove the Persians back into Asia; in five years after, they were compelled to receive the law from a Persian satrap; but after an interval of 80 years they revolted a third time, and resisted their invaders for 25 years; at length they yielded; and in the eighteenth year following, Egypt submitted to the arms of Alexander. During these wars the sciences ceased to flourish ; priests and learned men were sacrificed by Cambyses; the temples of the gods were defaced, their images mutilated ; and if in the most splendid eras of her prosperity the priests of Egypt never imparted their knowledge to the public, there is little ground to suppose that the remnant who guarded its last faint embers would be willing the conquering Greeks should light the torch of science in the dying flame. But when, where, and by whom the severer sciences of geometry and astronomy, as transmitted by the Egyptians to the Greeks, were constructed, is not easy to decide. At some remote period there were mathematicians and astro- nomers who knew the sun to be the centre of the planetary system, and that the earth, itself a planet, revolves round the central fire; who described the orbits, and calculated the returns of comets; who indicated the number of solar years contained in the great circle, by multiplying a period of 180 years by another period of 144 years; who reckoned the sun's distance from the earth by a measurement equal to 800,000,000 Olympic stadia, and who must therefore have taken the parallax of that luminary by a method little inferior to that now in use, and certainly much more correct than that adopted by Hipparchus; who fixed the moon’s distance from the primary planet at 59 semidiameters of the earth; who had measured the circum- ference of our globe with so much exactness, that their calcula- tions only differed by a few feet from that made by our modern geometricians; who held that the Moon and the other planets were worlds like our own, and that the Moon was diversified by valleys, mountains, and seas; who asserted that there was yet a planet which revolved round the Sun, beyond the orbit of Saturn; who reckoned the planets to be 16 in number; and who calculated the length of the tropical year within three minutes of the true time.—(See Sir W. Drummond's Essay on the Science of the Egyptians and Chaldeans. - Before the deluge, men lived usually 800 or 900 years. In so many years every individual had time to make great progress in knowledge; he could devote whole centuries to any one pur- suit; during as many centuries he could verify his experiments; and if a large proportion of society was then raised above the pres- sure of actual want, the arts and sciences of the descendants of Noah were in all probability as well known in the 2262 years that elapsed between the creation and the deluge, as in a few centuries they have reached so much excellence in modern times. - * Indeed, the Jews, Syrians, and Arabians, have numerous traditions of the astronomical knowledge of Adam, Seth, Enoch, and Ham. Seth lived 912 years, and to him the Hebrews' ascribe the invention of astronomy. He is the Egyptian During 720 years he could observe the stars, which, in º º º ºl T | - ** ---- *-*. º º º º º º - Uſuñº - - º - - . º º - º º º ſº |) Ll nº --- | I The zodiac of Esme (Latopolis. The Egyptian zodiac from ºne. ceiling of the Grana port. in the Temple of Isis at Dendera. º - - - | The Indian Zodiac, - º from the Philos. Trans. Fºremºs sº tº Yºº º tº ------- ºne-º-º-º-º-º-º-º-º-º- Z O D SCIENCE,. z o. D 1065 Diction ARY OF MECHANICAL this period, would have moved forwards 10°, or 3 of a sign. The descendants of Noah advanced in different directions from a common centre; hence we find all the Oriental nations in possession of a zodiac with 12 signs, with the exception of the Chaldeans, who were followed in this by the Alexandrian Greeks, who counted only 11, allotting 60° to Scorpius, and not admitting Libra, one common model must have served all these people and nations, for the emblems are all alike, and a single glance at the plate will set this matter at rest. Moreover, the Japetus of the Greeks, father of Altus, who is said to have invented the armillary sphere, is none other than the Hebrew scripture Japhet; and thus the testimony of the Greeks proves, that the immediate descendants of Noah were versant in astro- nomy, in which it is clear they must bave been instructed by the patriarch and his sons. * Though the Chaldeans always divided their zodiac into 11 signs, the Scorpion perhaps occupying two signs, as is alluded to by Ovid, lib. ii. v. 197, Metam. “Scorpios Porrigit in spatium signorum membra duorum.” But the Egyptians parcelled it into 12 signs, over which 12 gods presided. “AEgyptii,” inquit Servius, “ duodecim esse asserunt signa: Chaldaei vero undecim; nam Scorpium et Libram unum signum accipiunt ; Chelſe Scorpii Libram faciunt.” Yet, though we ascribe the division of the stars into constel- lations to the antediluvians, and assign to them the invention of the zodiac, it does not follow that the postdiluvian emblems and signs were identically the same as those which had obtained before the deluge. Amidst these changes, the Egyp- tians, the descendants of Ham or Cham, having adopted the worship of the host of heaven, would naturally choose such names and symbols as suited their purposes and situation; and while they retained the ancient divisions of the zodiac, they probably altered some of the emblems by which it was repre- sented. - Bvery thing in the zodiac of Dendera seems to prove that it owed its existence to the natives of the soil, and could not have been constructed in the age of Adrian and Antoninus Pius. The emblems and figures are all Egyptian. There is nothing Greek in the designs. All is Egyptian—astronomy, mythology, symbols, taste, style, manner. r The sun's place in the oblong zodiac of Dendera is indicated at the division of the two scarabae, or beetles. The small scarabaeus is next to Gemini, and the larger scarabaeus next to Leo. The former represents the ascending part of the sign Cancer, the latter the descending part of the same sign. The relative proportions of these beetles is as 17 to 13, or perhaps as 16 to 14. We consequently fix the date of this zodiac at the time when the solstitial colure corresponded with the 14th degree of the dodecatenorion of Cancer, according to the real zodiac. This nearly corresponds to the first year of the solstice period of which the Thoth, or beginning, may be fixed for the year 1322 B. c. It is now 2160 years since the sun at the sum- mer solstice quitted the dodecatemorion of Cancer, according to the precession of the equinoxes. And if to these 2160 years we add the 169 of ge descending, we shall give an existence of 3312 years, at least, to the oblong zodiac of Dendera. The book of Job has a higher antiquity than this, if, as is generally supposed, it was written 1700 years before our aera. Leo, however, was once a solstitial sign ; Taurus, then, opened the year. This was 2500 years B. c. The lion Hercules then sprung from Typhon. How did it travel from Egypt to Argolis : Thus:–the Nemean games were celebrated at the season when the sun in his annual course is in the sign of Leo. The Her- cul, (universal heat) the sun, took possession of the sign Leo, at the period of this annual festival. And why might not an Egyptian colony have settled at Argolis four or five centuries after the deluge? There is no difficulty in giving an affirmative answer, if the chronology of the LXX. be adopted. The Persian symbol of a bee entering the mouth of a lion, commonly known as the Mithraic lion, represents the sun entering Leo ; and this symbol may be referred to the period when the sun at the summer solstice was in the first degree of Leo. The Egyptians began their sacred year with the heliacal rising of Sirius, Siris, or Sothis, the star of Isis. The dog-star 115. º, - - is near Cancer, with which in Egypt it rises cosmically: the Roman year commenced with Aquarius; that of the Egyptians with Cancer. But I here observe, that Soth, a name of the dog- star, was also the name of an Egyptian divinity named Thoth, who also presided over this star; and Thoth seems to be the same with the Seth of scripture. - - Oriental scholars interpret Seth Thoth, Shoth, Thist, by pos. suit, pomere; and assert, that Seth, Soth, and Thoth, were only different names for the patriarch whom the Hebrews, Syrians, and Arabians, consider as the institutor of the sciences. Who has not heard of the two columns of stone and brick, erected by the descendants of Seth, and which Josephus pretends to have existed still in the land of Siriad in his time ! Manetho, who flourished 300 years before Josephus, says, he took his history from the columns placed in the Siriadi land, which had been inscribed in the sacred dialect, and in hieroglyphical characters, by Thoth, the first Hermes, before the deluge And the Ara- bians have a tradition, that Hermes, or Thoth, invented his books, or rather tables of brass or stone, in one of the pyramids, before the deluge. Sir W. Drummond thinks Nubia was Siriad; because the Nile, above Syene, was called Siri, or Siris. Per- haps the name of Seth, which the Egyptians corrupted into Thoth, which signifies the basis, and which, as a proper name, might indicate him who first established the civil year, was given to the patriarch who bore it, because he was the founder of the second race that sprang from Adam, and in the persons of Noah and his family were to repeople the world. ZODIACAL LIGHT, a brightness sometimes observed in the zodiac, resembling that of the galaxy or milky way. It appears at certain seasons, viz. towards the end of winter, and in spring after sun-set, or before his rising in autumn, and beginning of winter, resembling the form of a pyramid, lying lengthways with its axis along the zodiac, its base being placed obliquely with respect to the horizon. The zodiacal light, according to Mairan, is the solar atmo- sphere, a rare and subtile fluid, either luminous by itself, or made so by the rays of the sun surrounding its globe, but in a greater, quantity, and more extensively, about his equator, than any other part. Mairan says, it may be proved from many observations, that the sun's atmosphere sometimes reaches as far as the earth's orbit, and there meeting with our atmosphere produces the appearance of an aurora borealis. The length of the zodiacal light varies sometimes in reality, and sometimes in appearance only, from various causes. Cassini often mentions the great resemblance between the zodiacal light and the tails of comets. The same observation has been made by Fatio; and Euler endeavoured to prove that they were owing to similar causes. See “Deconverte de la Lu- miere Celeste que paroit dans le Zodiaque,” art. 41. Lettre a M. Cassini, printed at Amsterdam in 1686. Euler, in Mem. de l'Acad. de. Berlin, tom 2. This light seems to have no other motion than that of the sun itself; and its extent from the sun to its point is seldom less than 50 or 60 degrees in length, and more than 20 degrees in breadth; but it has been known to extend to 100 or 1039, and from 8° to 99 broad. It is now generally acknowledged, that the electric fluid is the cause of the aurora borealis, ascribed by Mairan to the solar atmosphere, which produces the zodiacal light, and which is thrown off chiefly, and to the greatest distance, from the equa- torial parts of the sun, by means of the rotation on his axis, and extending visibly as far as the orbit of the earth, where it falls into the upper regions of our atmosphere, and is collected chiefly towards the polar parts of the earth in consequence of the diurnal revolution, where it forms the aurora borealis. And hence it has been suggested as a probable conjecture, that the sun may be the fountain of the electrical fluid, and that the zodiacal light, and the tails of comets, as well as the aurora borealis, the lightning, and artificial electricity, are its various and not very dissimilar modifications. See Biot D’Astronomie Phisique, art. 254; and Gregory's Translation of Haüy's Philo- sophy, vol. ii. art. 628. ZONE, in Geography and Astronomy, a division of the earth's surface, by means of parallel circles, chiefly with respect to the degree of heat in the different parts of that surface. The ancient astronomers used the term zone to explain the diſſer- ent appearances of the sun and other heavenly bodies, with the 12 P ** * zsº * * sº. *** *s: * * º 5. fºr 'g * * **** ** i. * * * , -º ºr -, ºr zºº *. *. f* ... * * * & ? * a ... * * * . " .. " ** * º . . . º O N. ... " ** * *: $; ' '. Sº # § % Jºãº * - * * * ‘. length of the days and nights; and the geographers, as they used the climates, to mark the situation of places; using the term climate, when they were able to be more exact, and the its extreme heat. term zone when less so. The zones were commonly ageounted five in number; one a broad; belt round the middle of the earth, having the equator in the very middle of it, and bounded towards the north-and south by parallel-circles passing through the-tropic of Cancer and Capricorn. . This they called the forrid zone, which they supposed not habitable on account of Though sometimes they divided this into two equal torrid zones by the equator, one to the north, and the other to the south ; and then the whole number of zones was accounted six. Next from the tropic of Cancer and Capri- corn, to the two polar éircles, were two other spaces, called temperate zones, as being moderately warm ; and these they supposed to be the only habitable parts of the earth. , Lastly, the two spaces beyond the temperate zones, about either pole, bounded within the polar circles, and having the poles in the the middle of them, are the two frigid or frozen zones, and which they supposed not habitable on account of the extreme cold there. Hence, the breadth of the torrid zone is equal to twice the greatest declination of the sun, or obliquity of the ecliptic, equal to 46° 56', or twice 23° 28′. Each frigid zone is also of the same breadth, the distance from the pole to the polar cir- ele being-equal to the same obliquity, 23° 28°. And the breadth of each temperate zone is equal to 43°4', the complement of twice the same obliquity. The difference of zones is attended with a great diversity of phenomena. 1. In the torrid zone, the sun passes through the zenith of every place in it twice a ear; making as it were two Summers in the year; and the inhabitants of this zone are called Amphiscians, because they have their noon-day shadows projected different ways in dif- ferent times of the year, northward at one season, and south- ward at the other. 2. In the temperate and frigid zones the sun rises and sets every natural day of 24 hours. Yet every where, but under the equator, the artificial days are of unequal lengths, and the inequality is the greater as the place is farther from the equator. The inhabitants of the températe zones are called Heteroscians, because their noon-day shadow is cast the same way all the year round, viz. those in the north zone towards the north pole, and those in the south zone towards the south pole. 3. Within the frigid zones the inhabitants have their artificial days and nights extended out to a great length; the sun sometimes skirting round a little above the horizon for many days together; and at another season never rising above the horizon at all, but making continual night for a considera- ble space of time. The inhabitants of these zones are called Periscians, because sometimes they have their shadows going quite round them in the space of 24 hours. DroTIONARY OF MEcHANICAI, soºngº, Z U M ZOOLOGY, is that part of natural history which relates to animals. Linnaeus divides the whole animal kingdom into six classes, viz. Mammalia, includes all animals that suckle their young. Aves, or birds. Amphibia, or amphibious animals. Pisces; or fishes. Insecta, or insects. Vermes, or worms. The first class, Mammalia, is subdivided into seven orders. See MAMMALIA.—The second class Aves; is subdivided into six orders. See Aves.—The third class, Amphibia, is divided into two orders. See AMPHIBIA.—The fourth class, Pisces, is sub- divided into six orders. See Pisces.—The fifth class, Insects, is subdivided into seven orders. See INsect.—The sixth class, Vermes, is divided into five orders. See WeRMes,—For more particular information concerning the several branches and subjects of zoology, the reader may consult the varióus articles above referred to, and he will find most of the genera described in their order in the alphabet. * ZOONATES. Combinations of the zoonic acid with the salifiable basis. ZOONIC, is the liquid procured by distillation from animal substances, which had been supposed to contain only carbo- nate of ammonia and an oil. ZOOPHYTA, in Natural History, an order of the class vermes. Zoophyta are composite animals holding a medium between animals and vegetables. Most of them take root and grow up into stems, multiplying life in their branches and deci- duous buds, and in the transformation of their animated blos- soms or polypes, which are endowed with spontaneous motion. Plants therefore resemble zoophyta, but are destitute of ani- mation and the power of locomotion; and zoophyta are, as it were, plants, but furnished with sensation and the organs of spontaneous motion. Of these some are soft and naked, and others are covered with a hard shell: the former are by some naturalists called zoophytes, and the latter are denominated lithophytes. The coral reefs that surround many islands, par- ticularly those in the Indian Archipelago, and round New Hol- land, are formed by various tribes of these animals, particularly by the Cellepora, Isis, Madrepora, Millepora, and Tubipora. The animals form these corals with such rapidity, that enor- mous masses of them very speedily appear where there were scarcely any marks of such reefs before. t ZOPISSA, Naval Pitch, a mixture of pitch and tar scraped from the bottoms of ships that have been long at sea. This com- position, by having been gradually penetrated by the salt of the sea, becomes impregnated with its qualities; and being applied to the body externally, is found resolutive and desic- cative. ZUMIC AcID, a name given to a peculiar acid principle lately obtained from rice. F I N I S. * LoNoon : PRINTED AT THE CAxTon PRESS, BY HENRY FISHER, SoN, AND co, List of THE PLATEs. * ~ * -s . * - - Page. - - . -- ". *Page. FRONTISPIECE . . . . e G to face I | Mangles and Mills . . . . . . . . . . . . . 616 Africa, Map of tº º tº ºr tº º tº º 17 | Mechanics, Plate I. Mechanical Powers ... . . . . 636, America, North e Q tº º " tº Q e Q 31 —, ... II. . . . . . . ... 642. —, South .. ... .. © 4º. 34 —, ... III. Truncated Coſº Wheels ... 644 Anemometers, or Wind Gages . . º º © tº 41 || – —, ... IV. º e • . . ... 645 Arch, the Triumphal of Titus at Rome . . e s 54 || Microscope.—(See plate Optics, p. 742.) tº gº " " ' " Architecture, Plate I. Tuscan and Doric Orders .. 55 Mill, Bark-(See Mechanics, Plate II. p. 642) .. II. Ionic Order and Mouldings .. ib. , Barker's, do. do. do. tº e III. Corinthian and Composite Orders ib. —, Rustall's Family.—(See plate, Mangles and Asia, Map of G. G. & Cº C & © e 60 Mills, p. 616.) © º • . . . . . Astronomy—Solar System & O tº o ... . 68 —, Monk's Gunpowder.—See plate, Mangles and Balances . . . tº º G tº .. & © 84 Mills, p. 616.) tº @ tº ºr tº e Botany—The Classes, or Primary Divisions of the Mine, Bradley Coal.—(See plate, Observatory, &c. p. 731.) Sexual System tº gº tº Q tº e 119 Mint, Process of Coining at the Royal, Plate I. .. 678 Bridges .. e e • s tº Q ... 133 –, e & º e Plate II. . . . 681 Cannon Boring.—(See “Ordnance Boring,” plate Oil Navigation, Inland, Plate .I . • * ... 710 Mill, p. 738.) .. tº c tº gº tº º , ... II. . . e G ... 716. Cloth Manufacture.—(See article, Weaving, p. 1039.) Note, Bank, Specimen of a Patent Compound . . 726 Cog Wheels, Substitutes for .. º o ... 177 Observatory, &c. e G tº e © - ... 731 Coining, Process of.-(See article Mint) .. & O Oil Mill and Ordnance Boring C. C. ... 738 . Crystallization.--(See plate, Substitutes for Cog Wheels, Optics tº G tº e tº tº e Q ... 742 p. 177.) tº 9 tº ºn & O & O Piers and Suspension Bridges ... tº gº ... 805 Docks, London © ºr e G tº e ... 237 Pile Engines . . tº º tº º tº e ib. Drawing .. o ºt e Q e e ... 241 Pipes, Machine for Boring Wooden.--(See plate, Pile Europe, Map of .. tº e e Q . . 279 Engines, p. 808.) e O • * . . e. e. Flour and Flax Mills tº o tº tº ... 319 Ploughs .. & Cº. tº º © tº ... 815 Furnace, Lord Bute's tº º © O ... 775 | Presses, Printing tº º © o gº º " ... 840 Gas Light, Retorts for distilling Pit Coal ... 365 | Pump, the new Hydro-Pheumatic.—(See plate, Lord , Condensers, Purifiers, &c. tº Q ... 369 Bute's Furnace, p. 775.) tº º e G Glass Manufacture .. e e tº tº ... 391 ——, for Draining, H. W. Reveley's improved .. 885 Globes, Artificial e G tº G e - ... 393 | Quadrant and Telescope tº º - º º ... 861 Governors for equalizing the Motion of Mills, &c. 406 | Saw Mills .. tº Q © e © tº ... 912 Gunnery .. tº Q tº e & Cº. ... 420 | Scapements.... Q & e G Q -º ... 916 Gymnastic, Exercises .. © © tº . . 425 | Sluice tº o tº º tº º c ºn ... 944 Hand-Rails for Stairs, P. Nicholson's mode of Squaring 437 Steam, Engine of Twelve-Horse Power .. ... 961 Hemisphere, the Northern Celestial ... 191 , Parts of do. tº e tº G ib. , the Southern tº gº tº º O © ib. Strength of Materials, W. Rennie's Experiments on 968 Horses tº tº tº tº © & © Q . . 461 | Telescope.—(See plate, Quadrant and Telescope, p. 861.) Kiln for Drying Grain, Mr. James Jones's ... 539 || Vinery, a Double .. e e tº gº ... 1028 —, Improved Malt tº c. tº e ... 540 Watch, Mechanism of a common tº o . ... 1030 Light-House, Bell Rock tº Q © C. ... 797 Water Closet, Jordan's improved tº º ... 1033 Lamps, Dobereiner.--(See plate, Improved Malt Kiln, p. 540.) Weaving, Cloth Manufacture . . © º ... 1039 Lathes and Turning Apparatus, Maudsley's ... 560 || Windmills, &c. . . a & tº Q ... 665 Loading Machine.—(See plate, Observatory, &c. p. 731.) Woulfe's Chemical Apparatus .. tº º ... 1056 Looms tº Q e & .. Q - ... 594 | Wheels, L. Gompertz's Substitutes for . . . ... 1043 Maps, Construction of, Plate I. e - ... 618 Yarn Mill.—(See plate, Watch, p. 1030.)... tº Q 2 & © tº ſº Plate II. tº º ... 620 | Zodiacs, Ancient .. & © tº º ... 1064 *A To such of the Subscribers as desire to Bind this Work in two Volumes, we present suitable Titles, and advise that the second Volume commence with the letter L, sig. 6 Z, page 545. - Works PUBLISHED BY H. FISHER, SON, AND P. JACKSON, 38, Newgate-street, AND’sold BY ALL BooksellERs. I. 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