NOSTRAND'S SCIENCE SERIES. 50 Cts. MODERN REPRODUCTIVE GRAPHIC PROCESSES. JA8. S. PETTIT, First Lit iienant, First United States In f entry. /AN NO STRAND, PUBLISHER, 23 Murray and 27 Warren Street. 1884 C. E. Illustrated. No. 16. — A GRAPHIC METHOD FOR SOLVING CERTAIN ALGEBRAICAL EQUA- TIONS. By Prof. George L. Yoi With Illustrations. Date Due trated. MODERN REPRODUCTIVE GRAPHIC PROCESSES. BY | S J ' JAS. S. PETTIT, First Lieutenant, First United States Infantry. NEW YORK: D. VAN NO STRAND, PUBLISHER, 23 Murray and 27 Warren Street. 1884. Copyright, D. Van Nostrand 1884. PREFACE. The following pages were prepared for the use of the Department of Drawing of the U. S. Military Academy, as a basis for elementary instruction in, and with a view to the imparting of some analytical knowledge of the means em- ployed for the production of the many beautiful and useful prints, &c, that are constantly brought before the pub- lic, either in the publications \)f the day or in more artistic shapes. Each subject could be expanded into a separate volume. Those within the reach of ama- teurs, I have endeavored to explain at length. The others can be learned only in the school of long experience, and text books would be of little assistance. I am indebted to the courtesy of several publishing firms in New York, and to lit. Lusk, in charge of the laboratory at iv Willet's Point, for much valuable informa- tion, and to Messrs. Abney, Munckoven, Vidal, Vogel and Griffin for the use of their works on kindred subjects. J. S. P. I N D E X . Albertype 82 Applications of Photography 73 Aquatint e „ 114 Autoglyph 78 Autotype 78 Autocopiste Noir 13 B. Blue paper process 9 Bonnaudtype 123 c. Carbon prints 93 Cerography 48 Chromograph 12 Chromo-lithography 43 E Electrotypy " 29 Engraving 15 Etching 26 &. Gillotage 120 H. Hektograph 12 Heliogravure 110 Heliotype 80 Hoeschotype , 47 L Indotint 78 vi L. Lithography 35 Luxotype 121 M. Mezzotint 26 o. Oleography 46 P. Photography 53 Wet plate 56 Dry plate 62 Instantaneous , 63 Gelatine bromide of silver 68 Photogravure , . .105 Gamier 109 Photo-Lithography 40 Photoglyph 103 Phototype 87 Photo-Zincography 91 Polychrome printing 122 s. Sensitive papers 8 Similigravure 119 Stannotype (Woodbury) 104 Stereotyping 33 T. Transfer 97 w. Woodcuts 16 Woodbury type 103 z. Zincography 47 PROCESSES IN USE TO-DAY FOR THE REPRODUCTION OF WORKS OF ART, Mechanical, Engineering and Map Drawings. Befoke entering into a detailed de- scription of the various processes now in use in the reproduction of the many beautiful works of art, maps, mechanical drawings, illustrations, &c, it might be well to state that, due to the constantly increasing number of discoveries in the sciences of optics and chemistry, the great rivalry between large publishing houses, the diffusion of knowledge on art, and the increased appreciation of artistic things, many of the methods herein described are undergoing changes and improvements in the details, with in- creasing ranges in application. This is especially true of the various ap plica- 8 tions of photography. Good paintings, engravings and etchings, and fine photo- graphs will always be appreciated by ed- ucated people. The various patented processes must fluctuate with a very un- certain popular taste. I find the following to be the practical processes of the present day : 1. Sensitive paper processes. 2. Hektograph. . 3. Engraving. 4. Electrotypy. 5* Lithography. 6. Photography. 7. Miscellaneous. Mention must be made of the fact that many of the fine works of the old masters are frequently copied, not only by artists desirous of studying them, but by others for pecuniary purposes, and so skillfully is this done that the judgment of experts will sometimes fail to distinguish them from the originals, for which they are falsely sold. Sensitive Papers. — The process in gen- 9 eral use to-day in large manufacturing establishments, architects' offices, &c, is ordinarily known as the " blue paper " process, so-called because the sensitized surface turns from a dark grey to a blue color on exposure to the light and after washing. The drawing to be copied must be made on good, clear tracing paper, and with a very heavy opaque ink. It is then placed on a frame, on top of the sensitized paper, the frame having a heavy glass lid, which should press even- ly on the surface of the drawing and hold it firmly down to the paper. It is then exposed to the light for fifteen or twenty minutes. After sufficient expo- sure the sensitive paper is washed in a clean water bath. The parts affected by the light have become insoluble, while the parts screened by the interposition of the lines wash out, leaving the clear white of the paper on a back-ground of blue. The following formula is used in the laboratory at Willett's Point with most excellent results : 10 Double citrate of iron and ammonia loz. ) For use, mix equal quantities and float paper for two minutes. The mixture is poured into a flat dish. The paper is then taken by diagonally opposite cor- ners, giving it a convex surface. This convex surface is gently placed in con- tact with the surface of the liquid ; the corners are then dropped and the paper floats on the surface. The corners must be carefully lifted in a few seconds, and the air bubbles on the surface of the paper must be removed with a brush. After floating, the paper is placed in a dark place to dry, and must be rolled up and kept from the light until ready for use. The following process will give black lines on a white ground. The paper is coated with the sensitive solution by drawing it in continuous bands over a roller saturated with Water. 4oz. j" Red prussiate of potassium Water. 11 Sulphate of iron Chlorate " " Gelatine Tartaric acid. . . Dist. water 10 grammes. 20 c. c. 10 " 300 " 10 grammes. It must then be hung up to dry, pro- tected from the light and air. The draw- ing is made on tracing paper with a deep black ink. The exposure is made as in the "blue" process, and must be con- tinued until the ground is seen to turn white. It is then removed from the frame and immersed in the following solution : 200 grammes gallic acid, 20 " alcohol, 1,000 " water. It is then washed in water and dried. It is much more difficult to handle, and more expensive than the blue process, and is seldom used. I have been told the Major Jones, of the Corps of Engineers, obtained most excellent copies of the original drawing by using the following method. The 12 drawing was first made on tracing paper with a mucilaginous ink. This was transferred by the above-mentioned proc- ess to a paper which was sensitized with the silver solution, giving the drawing in white lines on a black surface. This copy was in turn placed over the same kind of paper, and after exposure and wash- ing he got excellent reproductions of the original — black lines on white paper. I have seen some maps and many machine drawings made by the " blue " process. They were very good, and suited to the purposes for which they were made. Of course this process would be too slow where a great number of copies is de- sired. Blue lines on a white ground give the most pleasing effect. Hektograph, or Chromograph (French). — This is an exceedingly useful and a very simple little arrangement of gela- tine for reproducing letters, manuscripts and small drawings which do not require great accuracy or much elegance. It is based on the discovery that gelatine forms an excellent body for receiving and 13 holding certain aniline inks. The draw- ing is first made on paper with hekto- graph ink, and is transferred to the gela- tine by simply pressing the drawing on the surface. If printed, while the ink is fresh, one good impression will admit of as high as fifty copies in fair condition. The violet ink seems to be the best and brightest. After the printing is com- pleted the surface of the gelatine must be washed off with a sponge and clean water. This is quite troublesome. The gelatine solution can be poured into a glass jar. When ready to print put the jar into hot water, and allow it to stand until the gelatine will flow. Pour a film on a glass plate as a photographer pours collodion. Allow this to set, and it is ready for use as prescribed for the hek- tograph. When through, heat the plate and wipe off the gelatine. Autocopiste Nora. — In order to avoid the use of aniline inks, which are very unstable, M. Lelm invented another process, called "autocopiste noir." It is very similar to Hektography in operation. 14 He makes use of a special ink, composed of a solution of the perchloride of iron and water, with coloring water added to enable the operator to see the lines he traces. The vehicle to which the trans- fer is made consists of gelatine, to which a little alum is added to harden the film., This is spread evenly on strong parch- ment paper. The drawing is placed face down on this, and is transferred to the gelatine by hand pressure, as in the Hex- tograph. After removing the original, a roller, covered with the prepared ink, which comes in tubes, is passed quickly over the film, as in lithography. The ink adheres only to the lines ; press the paper which is to receive the copy, on the film, with the hand, and then re- move it carefully ; re-ink the film and another copy can be taken. The pre- pared parchment is placed in a case which keeps it stretched. Before applying the original drawing to the gelatine the roll- er full of ink must be passed from one end to the other of the parchment sheet. If it takes any of the ink the entire 15 sheet must be wiped off with a damp sponge, and be thoroughly cleaned and dried. These prints have all the dura- bility of prints with a carbon base. The prepared parchment is put in a stretching case, and can be purchased ready for use. Engraving. — To engrave has but one signification, viz., that of marking by incision. The rudest mark, if it is cut into the substance, is engraving. Some of the applications of photography, such as the Heliogravure and Photogravure, are engraving, for the surface of the plate is cut away by the action of acids. Etching is also included under the gen- eric name of engraving, but has a tech- nical signification of its own. Engraving is older than printing, and dates from the first quarter of the 15th century. Wood engraving was learned from the Chinese. The process of print- ing from metal plates was not discov- ered until towards the close of the 15th century. Its history from that day to this is exceedingly interesting. It has 16 always been subordinate to painting, but some original work has been executed by good engravers. The apprenticeship to the art is necessarily long and tedious. The chased ornamentation of watches, silver-plate, &c, is engraving. I shall confine myself, however, to its technical signification as one of the fine arts. The following are the usual varieties of en- graving : 1. Pure line engraving* on metal plates, usually of copper or steel. 2. Mezzotint. 3. Wood-cuts : in which the lines that print black must be left in relief. In chronological order the wood-cut comes first. The genius of steel engrav- ing has not improved since the days of Diirer and Marcantonio notwithstand- ing the progress in means and materials. Wood engraving has, in the past thirty years, grown into a wonderful degree of excellence, and has widened into a range of application that covers almost all de- grees of artistic reproduction. As a "process" it is not surpassed by any 17 known invention, unless, perhaps, it be the Photogravure process, as executed by Messrs. Goupil & Co., in Paris. Some writers go so far as to claim that there is nothing artistic which can not be ex- actly reproduced on wood. The best of our wood engravers are, beyond dispute, the best in the world, and the beautiful prints published in our standard maga- zines have never been equaled in any country at any time. We may well feel proud of the progress of our country- men in this art, and a little time will do much for us in the others. It is difficult to believe that the work done by Cole, Miiller, Juengling and others can ever be excelled, and yet we cannot believe that perfection has been reached. The wood engraving of to-day has made no advance in principle over that of Diirer and Thomas Bewick. It fills a different sphere, and has been greatly assisted in the results of its practice to-day by the use of modern presses, paper, ink, photog- raphy, and electrotypy, though many of our best engravers prefer to work from 18 a drawing on the block rather than from a photograh. Photographs of paintings, engravings, &c., have frequently to be much reduced in size, and it is very difficult to work out an exact copy of the original. Again, red and yellow colors in a paint- ing take dark, and blue and violet take white in a photograph, so that it is nec- essary for an engraver to have the origi- nal by him for reference in order to give expression to the true color value of the painting. The history of engraving is long, but exceedingly interesting, and I must refer the student to other works written on this subject alone, as it is scarcely within the province of this article to give more than a description of the mechanical and artistic means em- ployed for the production of finished work. We may divide the process into five distinct operations, viz. : 1. The drawing or photographing of the picture on the block ; 2, the engraving ; 3, the mould- ing in wax ; 4, the electrotyping of the 19 mould ; 5, the setting and printing. Each operation requires special care, and the fineness of the original is a little blunted by each operation. The artist's proofs, obtained by methods of his own, and with much time and care devoted to printing, are much superior to the copies obtained from a powerful and rapid press, printing hundreds of copies in one hour. (1.) The Preparation of the Block. — A block of boxwood of unifrom thick- ness, and cut across the grain, is care- fully polished and cleaned, and is cov- ered with a light coating of Chinese white, giving a grey tint to the block. The drawing is made on this, either by the artist or by the engraver, or by the photographer, as the case may be. There are but few photographers competent to do this work without filling the block with silver, which interferes with the cut- ting. (2.) Engraving. — This, of course, is the main feature of the work, and to it the engraver must bring his artistic skill and genius, coupled with his own 20 particular method of working. If he be a true engraver his endeavor will be to thoroughly translate the genius and ideas of the artist whose work he is en- deavoring to place before the public. Herein lies the difficulty. Ihe lights of the drawing must be cut out so as to leave the darks, from which the print is to be taken, in clear, distinct relief. In this, wood engraving is more diffi- cult than its more aristocratic counter- part, steel engraving. In the latter the cross hatchings can be readily made with the burin without any trouble as to what will be left in relief, but the wood en- graver must cut out each little diamond- shaped space between the lines, and leave the edges clean and sharp. Again, if he desires to copy an engraving faith- fully, the little dots often placed in the diamond-shaped spaces by engravers on metal must be cut around and left. Such skill, however, has been reached by our good engravers that they can faithfully represent crayon or pencil drawings, line 21 engravings, etchings, and even the brush mark on paintings. After the engraving is finished and the block cleaned, a proof is taken ; if satis- factory a wax mould of the block is made. This is black-leaded, and electro- typed in copper, as will be described, and after being backed with type metal and "type high" wood, it is ready for the printer. The fine prints executed by the Century Co. and Harper Bros, are obtained with much labor and care. Cylinder presses with several inking rollers are used ; but one side of the paper is printed at a time, and dry paper is used. A light pressure proof is taken first, and an examination of this shows whether any parts of the form are too high or too low. The low parts are raised up by underlaying the block with bits of paper until the desired height is obtained. As all printing machines are made to give an even impression on all parts of the "form," cuts with strong contrasts of light and shade must be so arranged as to receive different degrees 22 of pressure, which should be very strong on the intense blacks, firm on the middle tints, and light on the others. This is obtained by the process of " over- laying." The pressman first prints a number of flat proofs on different thick- nesses of paper. The "overlayer" cutter compares these with the artist's proofs, and decides how many overlays he will need to produce the work to advantage. If he decides to use three overlays he cuts out of the proofs, skeleton figures of the strong blacks, of the middle tints, and of the lightest tones. He puts these accu- rately on the cylinder so that the strong blacks shall have three, the middle tints two, and the light grays one thickness of paper to increase the pressure on the corresponding parts of the electrotype, and these overlays must be attached to the cylinder and to each other, so that they will cover exactly the corresponding lines on the electrotypes. This work is necessarily long and tedious, but the beauty of the results amply repays for the time and care expended. 23 Many prints are made directly from the wooden block, but only coarse blocks can be used for a large number of copies, as printing in the rapid and powerful steam presses of to-day would soon blunt the sharp lines of the drawing and make the block utterly useless. It is impos- sible to obtain the pure, clean lines of an engraving in metal, from a relief plate. In the latter, the prints are merely dark- ened surfaces, and the ink must of neces- sity spread a little, while from the former we get a black cast of the line, with sharp, clean edges. Large wood cuts are frequently divided into sections, and executed by separate engravers. The blocks are then joined together and elec- trotyped as described above. We can readily see that the engravers must work so as to give similar tones to the differ- ent parts. What the future of wood en- graving will be can only be a matter of conjecture. It is at present passing through an era of favor and success Line Engkaving on Metal. — The man- ner of printing from an engraved metal 24 plate is the converse of that used in ob- taining a print from a wood cut. In the latter it is the raised parts, in the former it is the parts cut out which give the darks of the picture. The metal plate must be carefully made of a uniform thickness throughout, and the surface to be engraved must be carefully polished and cleaned. It must be free from blenv ishes of all kinds, as the slightest scratch on the metal will show on the print. The lines are cut with a little steel instru- ment called a burin, which is simply a small hand tool, with a (Q) diamond shaped edge, and which the engraver holds between the thumb and forefinger and pushes from him instead of drawing towards the body, as we would a pen or pencil. By varying the pressure the lines are made deeper or more shallow at the pleasure of the engraver, and the re- sult depends solely upon his genius and skill. Much of the engraving of to-day is done with machinery. The broad sur- faces of skies, foregrounds, etc., are readily and beautifully done in this way. 25 The plates are cut while soft, and are tempered before printing. The plate is covered with ink, either with a roller or a dabber. The surface is carefully wiped off, first lightly with a cloth, and then with the palm of the hand. The paper is slightly moistened, and the pressure of the press forces it into the incisions in the plate, from which it ab- sorbs the ink. The ink from the markings settles on the paper in strong, distinct lines, and the darks are much purer and stronger than in a wood cut. In block printing the line is only a blackened surface, in plate printing it is a cast. The line may be of exceeding fineness, it will print just the same. The art of line engraving seems to be doomed to extinction. There are still a few good engravers in the world, but engravings, if good, are ex- pensive, and, worse than that, their place in public and popular estimation has been usurped by the cheaper productions of the etcher, and the many excellent pa- tented processes based on photography. 26 Mezzotint. — For the Mezzotint the surface of the plate is first worked over in many directions with a small tool called a cradle, which is a chisel-shaped instrument with a circular edge, having many fine teeth. This gives the surface a fine grain, with many little projections. The parts are then cut away with a sharp instrument called a scraper, and at the pleasure of the engraver. The parts which are to print white are entirely cut away and the surface burnished. This process is better adapted to the expression of texture in garments, clouds, &c, than the pure line engraving, but the beauti- ful effects and expressions of the line are omitted. It is quite common to see the two combined in the same plate. The burin being used where it can be made most effective. Mezzotint plates are, unfortunately, not very durable, and after a few hundred copies have been taken, the little projections become blunted and the effects destroyed. Etching. — Etching is a species of en- graving in which the cutting is done by 27 the action of an acid. Pen sketches are very frequently and very improperly called etchings. Etchings are very pop- ular to-day, and are very handsomely ex- ecuted. The process is substantially as follows: To prepare the plate, it must first be covered with an etching ground, a composition that will resist acid, and it must be so adhesive that it will not quit the metal when fine strips are left iso- lated between lines, and yet it must be easily removed by the etching point. The following mixture is found to give an excellent body : Melt two ounces of white wax, add one ounce of gum mastic in powder, a little at a time, stirring un- til they are well mingled, then add in the same manner an ounce of bitumen in powder. To apply the ground to the plate the composition is melted, and a little of the essential oil of lavender is added. When the mixture is cool it forms a thin paste, which is applied to the plate with a small hand roller. The surface is then smoked by holding the plate over the flame of a candle or tallow 28 dip ; the drawing is made on this, and the composition is removed from the parts to be etched, by means of an etcher's point ; the acid is then applied, and the depth to which the eating is allowed to proceed is left to the skill and desire of the etcher, as the biting may be stopped out at any point very readily by remov- ing the acid. After the biting in is fin- ished and the composition removed the burin may be used in finishing up parts found to be insufficiently etched. The plate is printed from in the same manner as the engraved plate, and gives beautiful and very artistic results. Copper is the best substance to etch and engrave upon ; steel resists printing better, but is not nearly so agreeable to work upon, and does not yield such beautiful prints. Etching is the only form of engraving that has ever been practiced directly from nature. Etchers go out with their materials like painters or any other draughtsmen. Dry point is often used in connection with etch- ing. The lines are scratched on the 29 polished surface with a sharp steel point. Etching is extremely favorable to the imitation of textures such as the intricacy of lace work, the richness of velvet, the sheen of armour. ElecteotypYo — The ordinary form of a Daniell cell is a copper vessel containing a saturated solution of blue vitriol (sulphate of copper), inside of which is placed a porous jar containing dilute sulphuric acid. If a rod or strip of zinc be placed in the acid and be connected with the copper vessel by a wire, electrical action will immediately take place. The zinc plate will be gradually decomposed with a consequent formation of zinc sulphate in the porous cell, and pure copper will be disengaged from the sulphate, and will be found deposited on the surface of the copper vessel, the current passing from the positive generating zinc plate to the negative copper pole. By the use of a copper coin in some of the early experi- ments with electricity, it was discovered that a very perfect copy of the coin was formed^ with the exception, of course,, 30 that the copy was in intaglio; a bit of var- nish was accidentally dropped on the sur- face of the coin and no deposition of metal was found over the varnish, which was a non-conductor, and the operator saw that he had the power of directing the deposition at his pleasure The ap- paratus was for many years very rude. The strength of the copper solution had to be maintained by the addition of crys- tals of the salt, and the zinc plates, which were quickly eaten away, had to be re- newed. For carrying on the operation extensively, a large number of cells was necessary, and this method was replaced by the use of dynamo electric, or mag- neto-machines. If a coil of copper wire be revolved between the poles of an electro-magnet, a current of electricity will be generated in the wire at each half revolution ; in the next half revo- lution, a similar current will be gen- erated, but in the opposite direction. By means of a little instrument called a commutator, these counter cur- rents are converted into a constant 31 stream of electricity, and this current is utilized in the electrolysis. Large and powerful machines are constructed, run by steam-power. It is said that there is one at Birmingham which will deposit 4^ cwt. of copper in 24 hours. Wood en- gravings may be eiectrotyped by coating the surface with a wash of black lead and then placing the block in the current by a connecting wire. The finest scratches and the smallest ridges are faithfully re- produced. To obtain an exact copy of the object, the matrix or first plate is in turn eiectrotyped. The surface to be eiectrotyped must be perfectly free from stains and grease spots. The electro- typing of objects of the most delicate nature, such as Daguerreotypes and negatives (which are metallic), is now done with perfect ease. Insects, flowers, etc., may be faithfully reproduced by first immersing them in a metallic so- lution. The process of electrotyping is simple and moderately expensive. It is used extensively in the engraving department 32 of the Coast Survey office, with apparatus that will cause the deposit of from two to three lbs. of copper per square foot in 24 hours. The copy, after removal from the mould, is strengthened by a backing of type metal, and is then ready for the press. It is admirably adapted to map work, which is generally pure line-work. It is also the final step in many of the processes based on photography, both for the production of engraved plates and plates in high relief. The copper is sup- plied by putting a plate of the pure metal in the current in front of, and parallel to the surface to be electrotyped. Electro- plating is similar to electrotyping, except, of course, the deposit remains on the metal, and forms an inseparable part of the object. Many small objects can be electrotyped or electroplated in the same bath at the same time by simply attach- ing them to the proper pole of battery. For depositing copper, a solution of the sulphate is used ; for silver a solution of cyanide of silver, in cyanide of jDotassium ; for gold, the double cyanide of gold and (INSTITUTE potassium. It must be borne in mind that the cyanide of potassium is a rank poison. Stereotyping. — The process of stereo- typing a valuable work, for the purpose of saving it for subsequent editions, is now a very simple proceeding. In its early stages of development a plaster cast of the type form was taken, and this was in turn put through a troublesome process in order to obtain a metallic mould of the plaster ; defective parts had to be taken out and new letters or words set into the metal, and in addition to this the enor- mous quantity of metal necessary to stereotype a large work, made handling and storage quite important features. Electrotypy has completely changed this laborious process into one of easy manip- ulation, and certainly of good results. A sheet of wax, covered with a coating of graphite, is laid upon the type form, and is secured in a shallow pan called the moulding pan. Strong pressure forces the wax into all the interstices, and even into the lines of the wood cuts. 34 The moulding pan is then removed, and the impression is covered with a second coating of black lead, and is then placed in the electric circuit, and regularly elec- trotyped and backed. Mr. Silas P. Knight, of New York, pours a solution of the sul- phate of copper over the graphite, and then dusts on this fine iron filings. De- composition and recomposition take place immediately. The acid leaves the cop- per and unites with the iron, depositing a coating of pure copper on the mould, it is then placed on the circuit and kept there until the thickness of the deposi- tion is about that of blotting-paper. It must now be backed with strong metal, as printing would crush the mold out of shape. The shell is placed face down, and the back is washed with a solution of chloride of tin to make the metal adhere. A sheet of tin-foil is laid on this, and the pan is heated to about 460,° when the tin melts. Melted metal is now poured into the mould and a solid plate is formed. This plate is trimmed and made of the 35 proper thickness, and is stowed away for future use. Electrotypy does not cost more than the stereotype, it will wear much longer, and gives far more perfect im- pressions, as electrotypes are practically as good as the original blocks from which they were taken Lithography •< Photo-Lithography, In lithography we have one of the simplest and yet the most useful and most extensive of the industrial arts. It is based on the antagonistic qualities of grease and water. The greasy litho- graphic ink is made to adhere to a polished surface of a peculiar kind of limestone obtained in Bavaria. The parts thus covered acquire the property of re- ceiving printer's ink, which is prevented from adhering to the other parts by the interposition of the water. The lithographic stone is a very fine- grained homogeneous limestone, and is imported free of duty. It is cut into blocks of from two to three inches in Lithography, 36 thickness. Before receiving the litho- graphic ink, the face is carefully and highly polished, and the stone made of exactly the same thickness throughout. Some stone is obtained in this country, but it is too coarse for fine work. Litho- graphic ink is composed of tallow, wax, soap and shellac, about equal weights, and quantum sufficit of fine Paris black. It may be purchased in almost any market. The transfer paper is prepared by coating the surface with a composition of size or starch and glue, with a little gam- boge. This forms an excellent body for the reception of the ink, preventing the paper from absorbing it, and allows it to be readily transferred to the stone. The drawing is made on this paper with the ordinary instruments, when completed it is placed on the prepared stone, face down, and is run through the press ; the paper is then carefully pulled off, leaving the lithographic ink on the stone. The stone is then slightly etched by pouring on it a very dilute acid, giving the inked 37 lines a little greater relief. The work is then proven. Alterations may be made by simply scratching off the ink with a penknife or common eraser. The sur- face is kept moistened with water through- out the printing, and thousands of copies may be struck off of the same stone with- out a renewal of the drawing I saw some very fine specimens of map work being done by Messrs. Julius Bien & Co., for the Coast Survey office, and also for the Census Bureau. There is but little difficulty in producing excellent prints of pure line work by any of the processes described. It is the shading — the fine gradations from light through half tints to the strong darks that call for the skill of the artist. It is quite common for lithographers to print from etched stones, especially in the copying of small detailed drawings. The surface of the stone is smoothed and polished as before described; it is then coated with a ground of Paris black. The drawing is then made with sharp steel needles fixed in cane handles, leav- 38 ing clean white lines on- the face of the stone ; these lines are filled with the fatty ink ; the surface of the stone is cleaned with water and a piece of coarse flannel* and is then ready for the operator, or the ground may be removed and the stone cleaned, and the lithographic ink be ap- plied to the surface of the stone with a roller. The lines scratched in will re- ceive no ink, and we obtain white lines on a black ground. Lithographic chalk is often used for shading of large surfaces, and is applied m the same manner that we apply pencil shading. Fine shading on small surfaces, such as the shadows and gradations on a face, is frequently stippled in with a lithographic pen, which is similar in shape to the ordinary writing pen, but is stronger, and is unsplit. In searching for a process for the pro- duction of maps, of which a large num- ber of copies may be desired, making economy necessary, I doubt if one better than lithography can be found, certainly not in our country. The most excellent maps of the "Wheeler survey were made in Vienna by a secret process belonging to the Austrian Government. Lithography proved of great value to General Sher- man's army on the march from Atlanta to the sea. A wagon was fitted up with a hand-press, half a dozen small litho- graphic stones and the necessary materi- als. An operator was found, who, in ad- dition to being a good draughtsman^ understood the method of printing. The reconnoisance sketches and reports made during the day were turned over to him in the evening, and, by the following morning, lithograph copies were in the j)ossession of the officers entitled to them Many of the models now in the Academy bearing the names of Calame, Harding, Julien are excellent examples of the beau- ty and finish of lithographic work of some twenty to thirty years ago. General Abbott, in some notes sub. mitted to the chief of engineers, speaks of some impressions obtained by treating a newspaper picture with acid and trans- ferring the printer's ink to the stone. He says the effect was fine, resembling an 40 old etching. I was told by a prominent lithographer that the process is known in this country, but is not considered to be of any value, as a wood-cut is a poor basis on which to form a high grade picture, much better results can be ob- tained by copying the wood-cut directly on to the stone. Photolithography. — There are .several photolithographic processes, similar in principle, but different in detail. Photo- graphy is brought into use as a valuable aid to lithography. There is nothing to prevent the direct formation of the image on the lithographic stone by exposure under the negative ; but it would be difficult to handle stones of any con- siderable size. The result can be ob- tained in the following manner : A mix- ture of water, albumen (white of eggs), or of dry albumen, and bichromate of am- monia is passed over a lithographic stone, which has been thoroughly polished and cleaned. The excess of the sensitizing mixture is carefully rubbed off, and the surface of the stone dried, so as to re- move all traces of humidity. It is then exposed under the negative. Wherever the light has penetrated to the bichro- mated albumen it has rendered it im- permeable to water, while the other parts remain soluble. After sufficient exposure the stone is carried to the dark room, and the surface is uniformly covered with lithographic ink ; it is then immersed in a basin of water and the soluble parts are washed out, leaving the image on the stone, which is then treated with the acid and gummed, and is printed from as in the ordinary lithographic process. The difficulty of handling the stones has given rise to the use of a transitory support for the image and a transfer of this to the lithographic stone. From such transferred prints the original draw- ing is reproduced by ordinary surface printing. The paper which is to receive the image should be unsized and be tough and not easily torn or stretched. It is sensitized by immersion for three or four minutes in the following solution : 42 Potassum di-ehromate 44 grammes. Gelatine 44 to 60 „ Little Glycerine water 1 litre, and is then hung up to dry. As soon as it is dry it is exposed under the negative. After exposure the surface of the gela- tine film is carefully covered with a coat- ing of lithographic transfer ink, either with a roller, or by putting ifc face down on a lithographic stone, which has been coated with the ink, and subjecting it to light pressure. The picture is then de- veloped by floating the print, back down- wards, on a dish of water, at a tempera- ture of about 50°c. As soon as the lines appear as depressions on the film it is immersed in a warm water bath, to which a little alum should be added. The soluble gelatine is carried away, together with the ink that covered it, and the image remains formed of ink lines in relief on a gelatine back. This is re- inked with the roller, and is transferred to the lithographic stone, as in ordinary lithography. This process lends itself most readily to the execution of line work. 43 The original drawing should admit of some reduction in size, as the lines are slightly increased in width by this proc- ess. Some very good results have been obtained by this process, in the reproduc- tion of half tints. It may be necessary to use a sponge and tepid water for arresting the de- velopment. Various modifications of this process have been tried, but without any particular increase of excellency in work. The word lithography has long lost its etymological meaning. It is now applied indifferently to any impression made from an inkable surface by reason of the inverse affinities developed thereon for water and greasy ink. Chromo-Lithography.— Chromo-lithog- raphy is simply lithography in colors, and differs in no wise from ordinary lithography. It is a much more labo- rious process, as a separate stone must be made for each color, and it is con- sequently more expensive and slower than lithography in black. No better specimens of chromo-lithograpkic work can be found than the many beautiful cards printed on paper and also on satin by Messrs. Prang & Co. It is the great commercial process of the day, .and enor- mous quantities of this kind of work are required to meet the demands of industry and commerce. The difference between the show-bill and the satin card is not due to the process, but, as in everything else, to the quality of the materials used, and the skill and artistic taste and knowledge of the makers. Great care is necessary in making the drawings on the different stones, so that the various colors shall fit accurately into their places in the drawing. A " key- stone " is first executed and proved ; marks or small needle-holes are made for " registering " particular points of the drawing. This u keystone " is only used for making as many impressions on the other stones as there are colors to be em- ployed. I saw preparations for the print- ing of a card for which seventeen stones were to be used, and copies of this card 45 could probably be bought for from 15 to 25 cents. I have read a description of Mr. Eck- stein's new method for reproducing maps and drawings, for which he claims the following advantages : 1st. A color is printed in all its shades by means of one stone. 2d. All colors are printed by means of but three stones. It answers very well for map work, as all of the necessary colors can be readily obtained by the simple superposing of the primaries — blue, yellow and red ; but for the reproduction of art works, in which great varieties of color and tone are necessary, I am told it does not answer so well as the ordinary chromo-litho- grapbic process. His process is substantially as follows : A photographic negative of the object is taken, from which a positive image is formed on glass. This image is con- secutively transferred to the three pre- pared stones. Each stone is then polished and lightly coated with a mixture of as- 46 phalt, white wax, stearine and a solution of soda ; it is then exposed to the light, which makes the coating insoluble to a limited extent. It is then dried and placed under a line drawing machine, which covers the whole surface of the stone with fine parallel lines, by means of a blunt diamond, which takes away the coating without cutting the stone. The stone is then etched at the pleasure of the operator, as in ordinary etching, and on this depends the success of the operation ; so that the skill of a practised etcher is necessary after the etching is finished. The surface of the stone is washed w r ith turpentine, and the rem- nants of asphalt and ink removed. The color is then rubbed on, and the stone is ready for impression. His process for printing all gradations of a single color works admirably in topographical maps ; but for the repro- duction of art works, his process is more artistic than mechanical, without corre- sponding results. Oleography. — This is a name given to 47 a merely vulgar process, which is simply an attempt to adapt chromo-lithography to the purposes of imitating oil paintings. The print is mounted on canvas, sized and varnished, and is sold under the ordinary name of " Chromo." Zincogkaphy. — This process is simply lithography applied to zinc plates instead of to the stone. Zinc plates are cheaper, and more readily transported; but as the ink does not penetrate the zinc as it does the stone, the adhesion is not so strong, and accidents are liable to occur in the printing which would require the preparation of a new plate. Hoeschotype. — This is a new process of color printing in fac-simile, named after the German inventor. The follow- ing advantages are claimed for it over chromo-lithographic processes : More delicate gradations of tint and greater simplicity of processes, which requires only five printings, and its therefore im- mensely diminished cost ; also the almost unlimited number of copies to be ob- tained from the plates. First comes the 48 copy in photography and the transfer to the metallic plates, which are prepared with gelatine. Five such copies are treated successfully with the required proportions of yellow, red, blue, neutral and brown pigments, and the printings are taken off in the same manner. Under this process, by the adjustment of the relative proportions of the five combined colors, it professes to cover 1,620 dif- ferent tints. The specimen prints show surprising delicacy and variety of tone. — Portfolio. Cerography — A cerograph, as the name implies, is a drawing in wax. The earliest development of cerography consisted in making a drawing in a wax coating on a metal plate. The lines were drawn with an ivory point, and were cut through the wax to the surface of the metal, a mould of the wax was then taken and stereo- typed. Electrotypy has superseded the unsatisfactory stereotypic process ; but otherwise the process of to-day is the same. Messrs. Struther, Servoss & Co., of New York, do a great deal of this kind 49 of work, and furnish some very hand- some prints. It is exceedingly well adapt- ed to the reproduction of small maps, mechanical and engineering drawings, small landscapes and other illustrations without difficult gradations in light and shade. A copper plate, about of an inch in. thickness, is slightly oxydized on one face, and this face is covered with a coating of white wax, the composition of which is a secret. This coating is made of about the thickness of a sheet of blot- ting-paper, and is kept perfectly clean and smooth. The wax must be of such a nature that it will adhere firmly to the plate in the parts not cut away, and yet must be easily removed by the V shaped drawing instrument. The drawing is made on the wax, either by hand, or it is photographed directly from the original to the wax by a process not made public. The drawing completed, the lines are cut out of the wax, just to the surface of the copper. The lettering of maps is put in by simply pressing the type in the wax, 50 so as to leave a clean sharp impression of it in the proper place. The drawing is then " built up " with beeswax, so as to give the electrotype d lines sufficient relief. After the " building up " is com- pleted, the plate is electrotyped in the usual way. They also do some very good work in colors, and use only the three primaries red, yellow and blue. They get a suffi- cient number of tints for map-work by superposing these colors, as in chromo- lifchography. A separate relief block must be made for each of the primary colors. In preparing the plates for colored work, the waxed face is put under a line drawing machine, and is ruled in to the surface of copper. The electro- types taken from these surfaces give beautiful prints in the ordinary rapid steam press. The work done by this process is certainly most excellent. It is reasonably cheap and rapid, and is only executed m two places in our country. The process of M. Dulos is as follows: 51 A plate of copper is covered with the fol- lowing mixture : Ordinary Benzine^ Zinc, white ) This coating can be easily cut with steel or ivory points. The drawing finished, the plate is plunged into an iron bath, which deposits the iron only on the uncovered copper. If we desire to ob- tain an engraved plate, the varnish is removed and the plate is silvered. The silver is deposited on the copper, to the exclusion of the iron, by pouring a dilute solution of sulphuric acid on the plate. The iron is eaten out, and, by treating the plate with the ammoniacal sulphate of mercury, the relief of the silvered parts is slightly increased, and we have the lines in intaglio. A relief plate may be obtained of the same drawing by depositing silver in place of the iron. The process of M. Comte, for produc- ing a typographic plate, is somewhat Caoutchouc 52 similar to that of M. Dulos. He used the following solution : Gum Arabic ^ Mixed to a con- Zinc, white V venient con- Avignon, yellow) sistency. This solution is placed on a zinc plate, which has been carefully prepared. The lines are removed with a quill or an ivory point, leaving the naked metal. Lith- ographic ink is daubed into the lines, and the plate is cleaned with benzine, so as to remove all of the varnish, after which the plate is dampened and inked anew. The ink is received only by the lines which have previously been in con- contact with the greasy ink. A resinous powder is now carefully sprinkled on the greasy ink, and the plate is subjected to the action of dilute acid, until the desired relief is obtained. The greasy resinous varnish protects the lines of the drawing from the action of the acid. These processes are not, as will be readily seen, purely cerographic, but are allied to it. 53 For industrial uses, electrotypy answers much better than the purely chemical processes, based on the use of the salts of mercury. By making a good drawing in the wax, applying a coating of black lead and electrotyping, an excellent plate can be obtained, having the additional essentials of cheapness and rapidity of execution. The wax must have similar properties to that used in etching. The following formulas give satisfactory re- sults : A. Pure wax (white) Burgundy Pitch Kesin Asphalt Turpentine B. White wax Asphalt Black Pitch Burgundy Pitch Photography. — It will not be possible, within the necessary limits of this article, to give more than a general outline of 75 grammes. 90 15 60 a few drops. 60 grammes. 60 30 15 54 the principal operations in photography. It is a science of optics and chemistry combined. Its rapid progress, and the wonderful developments in its various applications in the past twenty years have spread it over almost every branch of human effort and knowledge. In astronomy, geography, lithography in artistic reproductions of valuable works, and in the departments of justice, its value cannot be overestimated. Its utility in time of war, and its value to the mili- tary man, was clearly shown in the war of 1870-71, and its range has manifestly widened since that time. In some foreign schools of technology it is carefully taught. It will reproduce in minutes, work which required weeks and months of hard and careful work, and with far greater accuracy than could be obtained by any other method. It takes long practice and some natural ability to make a good draughtsman. A few months of careful instruction in photography is sufficient. Good apparatus can now be bought at very low rates. It gives ample 55 returns in instruction and amusement for all of the time spent in studying its various applications. Before describing the various detailed operations, it will be necessary to briefly give the principles which make photog- raphy possible Various substances, such as the salts of silver, some of the salts of iron, urani- um and chromium, potassium dichromate, and a certain kind of asphaltum or bitu- men found in Judea, when exposed to action of the actinic or chemical rays of light undergo peculiar chemical changes, and if in the presence of some organic substance, such as collodion, gelatine, etc., they form new compounds with peculiar properties as to solubility. The parts acted upon by the light, become nearly insoluble in water, turpentine, etc., while the parts screened from the light remain soluble and are easily washed out. This action is so perfect that it extends admi- rably through the half tones and delicate gradations, enabling us to get a complete detailed picture. The extent of the 56 action depends upon the intensity of the light and the time of exposure of the sensitive plate. The actinic rays are found in the green, blue, blue violet and violet rays of the spectrum, and are very weak in the yellow and red rays ; so that the colors which appear brightest on the retina have the least effect on the negative plate. This explains why yellow and red objects print dark on the picture, and blue and violet print white. The process of taking a picture by photography may be divided into the following distinct operations : (1.) The Formation of the Sensitive Plate. — Glass is found to be the most sat- isfactory material to form the negative on; where but a single copy is desired it may be taken on paper, wood, or other sub- stance. The glass should be clear and must be thoroughly cleaned just before the sensitive solution is placed on it, as any specks of dust or grease spots on its face will injure the negative. It should be immersed in a bath of nitric acid and then thoroughly dried and rubbed with 57 a dry cloth. It is then ready for the collodion, which is almost universally used for a body, as it is particularly suit- able for holding the precipitable salts of silver, and is, for ordinary purposes, totally unacted upon by the sensitising solution. The plate is held by one cor- ner, and a circular mass of the thick fluid, to which a metallic iodide and a bromide, as of potassium, have been added, is poured upon the center and allowed to flow to each of the four corners by a gentle inclination of the plate, about half of the fluid remains and adheres to the plate, the remainder is poured off at a cor- ner. As soon as the collodion stiffens, the plate is immersed in the nitrate of silver bath. This is accompanied by a chemical change. The iodine and bromine salts change properties with the nitrate of silver, and give birth to the iodide and the bromide of silver and nitric acid salts. All of these details having been carefully conducted in a dark room, or in a room to which light is admitted through a yellow or 1 aby colored glass, the plate 58 is placed in the cassette or dark slide, and is ready for the camera, and the second stage of the operation, or (2). The Development of the Images. — The object is carefully placed in the focus ; the cassette is put in the camera: the slide is drawn out, and the light is allowed to fall on the sensitive plate. This is a very important operation. If the time of exposure is too short, the picture will be weak, if it be exposed for too long a time the bright lights will appear as great white blotches. The time must be regulated by the nature and in- tensity of the light, and is different for differently sensitized plates. It can be learned only by experience. The chemi- cal strength of the blue sky light varies greatly with the latitude of the place, the season of the year, and the time of day — southern latitudes. The summer season and mid-day give the most favor- able opportunities. Electric calcium and magnesium lights are actinic; moon- light, lamp and gas light, but very slightly so. After sufficient exposure, 59 the slide is replaced and the plate re- moved to the dark room. The image is as yet invisible, and must be brought out and developed by some chemical agent. The light has peculiarly affected the iodide of silver, the principal constituent of the plate, changing it from the iodide Ag 2 I 2 into the subiodide Ag 2 I, leaving but one atom of silver saturated and the other free to combine with any substance for which it may have an affinity. A so- lution of green vitriol (Ferrous sulphate) is gently poured on the plate. The silver is precipitated on the plate, and the picture slowly makes its appearance; first the lightest parts, such as the shirt and the face, then the darkest. The picture may not be strong enough yet, and must now be put through the op- erations of (3). Intensifying and Fixing. — After the development the plate is washed with clean water, and the picture is intensified by repeating the process of development. A mixture of green vitriol and a solution of silver is poured upon the plate and 60 more silver is thus precipitated. After the image has been sufficiently intensi- fied, in the judgment of the operator, it is fixed by pouring on the plate a solution ' of the hypo-sulphite of sodium, or the cyanide of potassium. This dissolves out the surplus salts of silver, leaving the image intact in metallic silver. The plate is now washed and dried and covered with a varnish for protection, and is ready for the (4). Printing. — The negative shows everything reversed — the white face is black and the black coat is white, hence a positive must be obtained from this. It is also evident that the relations of light and shade are not correct ; all defects in the original are faithfully re- produced in the negative ; and, indeed, so sensitive is the plate, that many marks on the object, not visible to the eye, show plainly as spots on the negative. Vogel relates an incident in the taking of a portrait of a lady, on which many dark spots were found on the negative of the face. As the lady had a fairly good com- 61 plexion, these spots excited the curiosity of the photographer, and he learned that three days afterwards she was taken ill with the small pox. The negative had forestalled the eye in its detection of the disease. These defects were formerly marked out of the pictures as they were printed, but now they are changed on the negative, which is carefully retouched with a camel's hair brush and India ink or ver- milion. A piece of paper, coated with the white of egg, and moistened with a solution of kitchen salt, is laid in a dish containing a solution of nitrate of silver. Chloride of silver is formed on the surface of the paper through the action of the salt (chloride of sodium). The white of egg takes the place of the collodion used on the negative. The paper is now dried in the dark and becomes fully sensitized. It is then placed in the printing frame, under the negative, and is exposed to the light. A faithful positive is formed on the paper. It is then removed to the dark room, and the superfluous salts washed 62 out, as described, for the negative. It is then immersed in the hypo-sulphate of sodium solution, from which it un- fortunately suffers a disagreeable change of color, and must be toned down ; this is effected by immersing it in a di- lute solution of chloride of gold. It is then fixed with the hypo- sulphite and thoroughly washed, after which it is dried out into regular shape, mounted on card- board, touched up, and rendered glossy by two smooth steel rollers. Such is substantially the wet-plate process of photography. The dry-plate process is much more convenient for amateurs, as the plates can be purchased ready for use, and will remain good for long periods if kept in a dark and dry place. These plates are prepared in the same manner as the wet plates, except that the addition of some organic substance, such as tannin, morphine, caffeine, having chemical relation with iodine, is necessary, as it allows the coating to become dry without injury. After being dried, the 63 plates are given a light coating of var- nish for protection. Pyrogallic acid and a solution of silver is used in the develop- ment and intensifying. Potassium oxa- late and ferrous sulphate may be used in the development. The negative is fixed with the hyposulphite of sodium. Instantaneous Photogeaphy. — This is an important feature in the study and practice of the science of photography. It is particularly valuable to the military profession. It enables us to obtain beau- tiful and accurate representations of the effects of torpedo explosions, the explo- sion of mines, the firing of heavy guns at experimental targets, movements of troops on the field at any particular moment, etc. One of the various emul- sion processes is generally used, pref- erably the gelatino-bromide process; it gives very sensitive plates. The medium used for holding the sensitive salts in solution is gelatine, which gives valuable qualities to the image. They are pre- pared with an excess of the sensitive salt, preferably the bromide of silver. 64 The gelatine is soaked in water and heated, while the solution is hot, potass- bromide is added and then the silver nitrate, with constant stirring, ; the emulsion is then poured into a dish and allowed to set ; after setting it is cut into strips and washed for several hours, with constant changes of water. It is then dried, and is warmed and poured on the plate. The operations of developing, in- tensifying and printing are the same as described for the ordinary negative ; greater time is necessary in developing and intensifying. Pyrogallic acid pot- bromide, a little ammonia and distilled water may be used in developing and intensifying, and the hypo- sulphite for fixing. * * * * The science of photographing colors is not yet fully developed ; enough has been accomplished to show the possibility of it ; and we may expect the discovery of the secret at no very distant day. In fact a German photographer has suc- ceeded in taking some good color work, but it fades out very quickly. "With the de- 65 velopment of this branch of photography- its range will be vastly increased. Pic- tures of nature, copies of the many beautiful works of the old and of the modern masters, true in all of the details of color and light and shade will, we trust, soon supersede the many poor and false pigment prints now forced on the public. In connection with the discussion of photography in colors, it may be interest- ing to learn something of the work already accomplished. We know that the solar spectrum is composed of seven distinct colors — violet? indigo, blue, green, yellow, orange and red. These colors are indecomposable, however. If we project red on blue we get the violet, yellow and blue give green, and yellow and red give orange rays. We have then Violet == red + blue. Indigo = violet + blue. Green == blue + yellow. Orange = yellow -f- red. If we combine the common factors, we 66 get violet 4- indigo + green -f orange = red + yellow + blue. That is to say, with combinations of red, yellow and blue we can reproduce all of the colors of the spectrum. If, then, we look at an object through a green glass, the rays which pass through the glass and reach our eyes are found in the blue and yellow regions of £he spectrum, the red rays being stopped out by the green glass. With an orange glass the blue rays are arrested, and with a violet glass the yellow rays are stopped. "We come now to the following synopsis : Green glass -s j i f red isolated, If, then, we make three negatives, in- terposing between the sensitive plate and the object ; first a green glass, then an orange, then a violet one, we will get plates upon which for the first, the red Violet Orange 67 rays will have had the least effect, for the second the blue, and for the third the yellow rays. The process then as used by M. Gros and M. Ducos, du Hauron, consists in the production of three neg- ative plates, as described above, preserv- ing the same dimensions in each. The negative obtained with the green glass serves for the printing of the red mono- chrome, the second for the blue, and the third for the yellow. Then following the idea of the inventors, the superposing of these three monochromes should result in a reproduction of the colors of the natu- ral objects. But when we think of the com- plications and difficulties attending the production of these three separate neg- atives with the varying times of exposure, made necessary by the different actinic properties of the glass plates, and added to these the complications of light and shade, we cannot make any serious com- parison between the results and the orig- inals. As I stated in the article on pho- tography, the red rays of the spectrum are practically non-actinic, as the orange 68 and the violet plates contain red, the pro- duction of the negatives from those col- ors is attended with increased difficulties. M. Guntrel conceived the idea of add- ing to the three plates already described, a fourth plate in black from which the shadows were to be obtained. This proc- ess is interesting as showing what can be done in the development of artistic fancy and genius, but is, I should say, more properly a method of polychrome printing, than of photographing colors. There exists in nature a multitude of colors, grays, browns, neutral tints, and all gradations of violet, green, orange, &c. We can scarcely expect to repro- duce these accurately in pigment by the superposition of the three primary colors, red, yellow and blue. The gelatino-bromide of silver process is destined to take the lead in photog- raphy, because of its extreme simplicity, its great rapidity, and the facilities it of- fers for dry plates. The amateur can procure the plates already prepared, and by studying for a few days, the manipu- 69 (lliSTIT lations in the development of tb$ image can obtain results which were, until very recently, in the exclusive domain of tlie~ specialist. The image may be developed either by using the Pyrogallic acid bath or a solution of iron. The latter seems to be preferred by prominent photograph- ers. Dr. Munckhoven used the following bath : In one-half liter of boiling water, dis- solve 100 grammes of the neutral oxalate of potassium, and 50 grammes of ferrous lactate in powder, stirring the mixture. Filter as soon as cold, and add a small quantity of the following solution : Water 1,000 cent, cubes. Br. of ammonia. 100 grammes. The Bromide solution slightly retards the development of the image, but de- creases the liability of fogged plates. Dr. Eder, of Vienna, prescribes the following formula : A. In a liter of dist. water dissolve 300 grammes of pure sulphate of iron, add 3 drops of sulphuric acid, then filter. The 70 solution should have a pale emerald green color. B. In one liter of dist. water dissolve 300 grammes of the neutral oxalate of potassium, then filter. C. Dissolve 10 grammes of bromide of ammonia in 100 grammes of dist. water. To prepare the bath for use, take 3 parts of B, to which add 1 part of A, a little at a time with constant stirring. This bath will remain good for about two days. The quantity of C to be added depends upon the emulsion employed, and the effects desired without the chromide. The negatives are very soft but are easily fogged. To 400 cubic-cent, of the developer, 2, 4, 6' or 8 cubic- cent, of the bromide may be added. Use the hypo-sulphate for fixing. The following "General Purpose De- veloper n is given by Lt. Griffin : Ferrous sulphate 100 parts White rock candy 25 " Glacial acetic acid .... 32 66 Alcohol 32 « Water 1000 " 71 This may be strengthened or weakened by the addition or subtraction of the sul- phate. For intensifying (Capt. Abney). No 1. Pyrogallic acid. 4 grammes. Citric acid 4 to 8 * Water 1 liter. No. 2. Ferrous sulph. 10 grammes. Citric acid 20 " Water 1 liter. To each of the above a few drops of the following solution must be added im- mediately before application to the film. Silver nitrate. 20 grammes. Water 500 cubic-cent. For fixing (Munckhoven), (1) Cyanide of potassium. 20 grammes. Dist. water 1 liter. (2"> Hypo-sulphate of so- dium. 1 00 grams. Dist. water 1 liter. For silver nitrate bath, 72 (Wet process.) Dist. water. 1 liter. The cyanide is poisonous and should be used very carefully. A few drops of the bromide of potas- sium added to the iron solution will re- tard a too rapid development of the image. The following defects in negatives must be carefully guarded against and steps taken to remedy them. "Fog," on the negative, this may be due, 1st. To a dirty plate. 2d. To im- proper exposure to the actinic rays either in the dark room, or in the camera. With the dry plates ; storage in a damp place will injure the plates and give clouded results. 3rd. To want of acid in the de- veloper. 4th. To the presence of vapors in the developing room. A weak image may be due to unsuit- Nitrate of silver. . . . Iodide of potassium Nitric acid 80 grammes. 2 drops 1 liter =1.05 quarts. 1 gramme =15.432 grains. 73 able collodion, dull or cloudy weather, organic matter in the bath, or an over- strong developer. Pin holes may be caused by the presence of dust in the plate, or the bath being over-iodized. Black specks are usually due to dirt on the camera, or on the lens, or on the collodion. A want of sharpness is often caused by improper focusing, or by an accidental shaking of the camera during the expos- ure, or by slight unsteadiness of the ob- ject. For most of these defects the rem- edies are apparent, and practice will soon enable the amateur to judge of the various causes of the defects in his nega- tive. Order and cleanliness and purity of chemicals are necessary aids to good work. APPLICATIONS OF PHOTOGRAPHY. The processes of reproduction based on photography are numerous and some of them very detailed in operation. So much depends upon the skill of the oper- ator that it is scarcely possible for an 74 amateur to obtain more than fair results. It is difficult to tell how much of the beautiful work produced is due to skill in handling, and how much to the prop- erties inherent to the process. Most of these processes are patented, and some of the most important details are care- fully guarded secrets. Enough is known, however, to enable us to describe the methods of applying them to the repro- duction of line work. The photogravure, carbon prints, and heliotypes seem to occupy prominent places in public estimation. The first, as produced by the Paris firm of Messrs. Goupil & Co., have no superiors in the line of artistic reproductions. In the re- production of paintings by these proc- cesses much is gained by photographing the picture, if possible, in the same light as that in which it was originally pro- duced. This enables the operator to get a correct negative so far as the light and shade of the drawing or painting is con- cerned. It is quite difficult to make an exact 75 classification of the various processes em- ployed. A very general classification might be made on the following scheme : 1. Collotype printing, or those proc- esses on which the print is taken directly from the gelatine film. To this class be- long the autotype, albertype, autoglyph, or indo-tint, and the phototype. 2. Those on which the film is transfer- red to a provisional backing as a means of support, as the heliotype. 3. Those on which the film is used as a basis, from which plates either in high or in low relief may be obtained, either by etching or by building up parts of the metal. To this class the heliogravure, some varieties of photozincography, photogravure, and the various processes based on the use of the salts of mer- cury or copper, &c, belong 4. Those in which the film is used for obtaining a mould of the image in soft metal, as lead, tin, or pewter, from which the impressions may be taken. In this class we have the Woodburytype or 76 photoglyph, and the photogravure proc- ess of M. Rousselon. 5. A miscellaneous class, which com- prises many methods, and great variety in treatment. As the dichromates of potassium and of ammonia, and the sensitive bitumen of Judea, are the sensitizing agents in gene- ral use in the processes about to be de- scribed, it may not be amiss to go a little into the general chemistry of the operations. In the presence of organic matter, the bichromates just mentioned become rather unstable compounds, and if sub- jected to the action of the light, decom- position and recomposition begin imme- diately. The dichromate of potassium (k 2 ci\ o 7 ) readily parts with its oxygen and potassium, giving, with the aid of the organic matter, a chromium, oxide, a potassium salt, and a slight change in the molecular construction of the organic matter with a probable loss of hydrogen. The image would then remain as a chromium salt insoluble in water, while 77 the potassium salt, readily soluble, is easily washed out, giving us the utmost simplicity in the process of development. The ammonia salts are very analogous in action to the salts of potassium. The bitumen of Judea is a very important agent in many of the processes now in use, being especially valuable on account of its great resistance to the action of the acids used in the production of en- graved plates. It is readily soluble in benzole, turpentine and chloroform. After exposure to the light it loses excessive solubility, and it is quite practicable to dissolve away from a thin layer of it, all of those portions which have not been acted upon by the light. It seems that daring exposure it becomes oxidized to a certain extent. Collotype printing is made possible for half tints by the peculiar property gene- rated in the chromatized gelatine for receiving printer's ink in direct propor- * tions to the action of the actinic rays through the negative plate, and it is also absorptive or repellent of water in a simi- 78 lar degree, so that when a roller, charged with greasy printer's ink, is passed over the surface of the film after the applica- tion of a wet sponge the ink adheres co- piously to the parts corresponding to the deepest shadows, and in a lesser degree to those corresponding to the half tints, the pure whites being dis- solved out with water. In the autotype and albertype proc- esses a smooth or a ground plate glass acts as a support for the gelatine film during development and printing. In the autoglyph or in do -tint a copper plate polished and slightly mulled with emery powder forms the backing. In the heliotype the gelatine film is trans- ferred as a pellicle to a thin zinc plate, and then printed from. None of these processes leave a plate mark in the print, and after printing the prints are gener- ally trimmed, mounted and glazed. In the autotype and the autoglyph or indo-tint processes, the sensitive com- pound consists of a from 6 to 7 per cent, solution of gelatine in about equal parts 79 of alcohol and water, which after perfect dissolution is sensitized by the addition of 1 or 1^ per cent, of ammonium bi- chromate Fish glue, glycerine, soluble glass and chrome alum are sometimes added according to requireniGnts. Both plate and solution having been warmed to about 100° F., a rather strong and very even coating is applied, and the plate placed on a level shelf in the drying box, where it is left in a temperature of from 120° to 130° F. until thoroughly desi- cated, a second coating of the same mix- ture is then applied, wmich is generally made a little thinner than the first by al- lowing more of the excess of the solution to run off the edges of the plate, the lat- ter is restored to the drying closet, dried, cooled, and is then ready for printing under the negative. In using this gelatine film the progress of the printing cannot be examined as such a print on paper, and recourse must be had to a photometer as with the negative process, the time of expos- ure depends entirely on the strength of 80 the light and the quality cf the nega- tive. Heliotype. — In the heliotype process both the sensitive compound, and the manipulations in the preparation of the film are somewhat different from those just described. Eight parts of gelatine are dissolved in 100 parts of water, and four parts of potassium bichromate are added, together with a small amount of chloride of silver. The addition of JJ- per cent, of glycerine and the same amount of chrome alum is recommended. The chrome alum slightly hardens the film. The solution being prepared and filtered, plates of ground glass are rubbed with a thin solution of beeswax or benzine, and leveled accurately on a table by means of wooden wedges or screw eyes. The necessary quantity of the gelatinous mixture is then poured upon the center of the plate, 1 oz. to every 34 square inches, and spread with the finger to within J inch of the edges. This may be done in day light, as bi- chromated gelatine is altogether insensi- 81 tive when wet. As soon as the gelatine has set, the plates are removed to the drying room, where they are placed on shelves in a sloping position, and left to dry for 48 hours in a current of air, the temperature averaging 80° F. When dry. a wet sponge is passed over the edges of the film, a knife inserted under one corner, and the pellicle, resembling a thick sheet of oiled paper, is pulled from the plate. In order to lessen the re- lief characteristic of gelatine treated with water after exposure under a negative, the film is placed face — that is, ground glass side — down upon boards covered w T ith black velvet, and their backs are then exposed to diffused light for about twenty-five minutes, the proper duration of this sunning being governed by an actinometer. After this they are placed in a printing frame and exposed under a negative. After exposure the pellicle is ready to be transferred to its final support, which is done by floating it in a tank of clean water on a zinc plate coated with a solu- 82 tion of rubber or benzine. A squeegee is then passed two or three times over its surface, and the plate is, without washing, transferred to the printing press. The composition of the inks, and their application to the cliche are iden- tical in all of the processes. Two inks are used, of which one is rather stiff and black, and is intended for the shadows only, while the other is rather thin, and generally toned by the addition of a little carmine, rose madder and cobalt, and is applied to the rendering of the halftones and subdued lights of the picture. The first ink is applied under rather a strong pressure with a leather roller, the second by a light sweep of a composition roller. The processes described above are in use at the laboratory at Willett's Point, and excellent results are obtained under the skillful management of Sergeant Von Sothen of the U- S. Corps of Engi- neers. Albertype. — This process, invented by M. Albert, of Munich, is very similar to the one just described. M. Albert has 83 brought Ms process to a high degree of excellence, and furnishes prints in all sizes, from card size up to sheets 20x30 inches in size, and has taken as high as 200 prints from a single film in a day. A thick glass, finely polished, is placed polished face up, and covered with the following solution : 6 grammes gelatine, 300 " dist. water, 5 to 6 u bichromate of ammonia. The gelatine is first placed for half an hour in cold water ; it is then warmed to about 40° C, and the bichromate is added little at a time. To this liquid is added 100 cubic centimeters of albumen ; when the mixture has cooled to about 25 or 30° C. it is beaten rapidly and then filtered in warm place, and is then poured on the glass and placed in a box to dry. The interior of the box being kept at a tem- perature of about 30° C. After the gela- tine is set the plate is put in a black cloth, the gelatine next to the cloth, and the glass side is exposed to the light for 5 or 10 minutes. The gelatine next to 84 the plate becomes insoluble, and adheres to the plate, which is now ready for the second coating. The plate is now plunged for half an hour in cold water, and is then dried in a vertical position. The second phase of the proceeding consists in covering the first coating of gelatine with a second, composed as fol- lows : (a) 20 grammes of gelatine softened in cold water. 125 grammes of dist. water, cold. (b) 4t grammes of fish glue, finely di- vided and softened in 60 grammes of cold water. (c) albumen beaten white and allowed to settle, and filtered through a cloth. (d) 10 grammes of bichromate of potas- sium dissolved in 60 grammes of dist. water ; filter. (e) 5 grammes lupuline, ) arestir- 3 grammes benzine, >• red 12 2 grammes Tolu balsam, ) h'rs in 100 grammes aqueous alcohol (at 8° Gay Lussac). 85 (/') 1 gramme nitrate of silver, 30 grammes dist. water. (g) 2 grammes bromide cadmium, 2 grammes iodide of cadmium, 30 grammes water. Of these different solutions mix first (a) and (&), when the liquid has reached about 35° C. add of (c) about 6 grammes. " (d) " 36 *t (e) " 4 66 "(f) « U " «(g) « 45 " This will produce a precipitate in the mixture, which must be shaken and fil- tered into a flask and maintained at 35° C. in temperature. The gelatine-covered glass is immersed in tepid water 40° C. until the water will flow in a continuous sheet over its surface. It is then dried for half an hour in a vertical position, and is then covered with the prepared mix- ture and is placed in a horizontal posi- tion to dry. Very thin films are good for the reproduction of line drawings ; thicker ones are better for the half tints. The 86 dried film is placed on the printing frame under the negative, and exposed to the light until the shades of the image are visible through the glass. After suf- ficient exposure the plate is plunged in cold water, and the superfluous potas- sium and chromium salts are washed out. The plate is then dried in a vertical po- sition. Before submitting the film to the printing it is immersed for 4 or 5 min- utes in cold water, to which a little glyc- erine has been added. It is wiped off with a dampened sponge, and then rubbed with a flannel cloth and a little oil. The inking can then be proceeded with as de- scribed above. The film should not be allowed to become completely dry during the printing. It should be wiped first with a damp sponge, and then with a sponge moistened with water and sul- phuric ether. A solution of fresh fish glue, bichromate of potassium and albu- men will suffice instead of the abo ve com- plicated formula as used by M. Albert. The best quality of gelatine should be selected. The proofs obtained by ML 87 Albert resemble the most beautiful silver print photographs, and leave nothing to be desired in the way of fineness and half tints. Of course extreme care is necessary for the reproduction of first- class work. The glass plate must be thoroughly cleaned with acid and dry cloths, and must be entirely removed from the presence of dust and the action of the light in the dark room. Phototype. — The processes just de- scribed are phototypic M. VidaFs phototypic process differs from that of M. Albert in some of the details. The liquid containing the sensi- tive matter is formed of Gelatine 90 grammes Water 720 " Isinglass 30 6i Water ........... . 360 " Bichromate of potassium 15 " " " ammonia. 15 " Water 360 " This is applied as a second coating after the first, composed of 88 Albumen . "Water . . . Ammonia 180 grammes, 150 100 Bichromate of potassium 5 4 £ has been applied, and the plate treated as in the process of M. Albert. After ex- posure and development he plunges the plate in a bath of Water 180 grammes. Alum 2 " and allowing it to remain for from 5 to 10 minutes. It is then placed vertically to dry. The plates are dampened before the inking by immersing them in a bath Glycerine. . * » . 40 grammes The glass plate is then placed on the bed of the press on top of a white blot- ting paper which has been immersed in a solution of Benzine . .... 100 cu. cent. Caoutchouc . . 10 grammes. Different kinds of cylinder presses can be used for taking phototypic impres- of Water 100 cu. cent. 89 sions, that is, such as might be employed in printing from an engraved plate. A thin sheet of caoutchouc should be placed between the back of the paper and the cylinder. The presses generally used for phototype printing are similar to lithographic presses. The inking is done mechanically, and from a good plate from 1,000 to 1,500 prints can be taken per day. I have gone considerably into the details of these processes, .as they are probably the most important ones within the possibilities of amateurs. In photo- typic printing with a strong press a hard film is necessary, else it will soon be de- stroyed. The process of M. Gbernetter, of Munich, seems to be the most satisfac- tory one in use to-day. The mounting, varnishing and satining of phototypic proofs is readily acquired with a little practice. If printed on sized paper the varnishing can be proceeded with as soon as the printing is dry ; if the paper is unsized the print must be gelatined before varnishing. Dissolve 100 grammes of white gelatine in 1,000 grammes of 90 water, and apply it to the print with a brush. There is no process which lends itself so readily to all kinds of work as this. It is very usefully employed in the illustration of editions de luxe, and, thanks to mechanical appliances for printing, good prints are produced very cheaply. Phototype-process of M. Obernetter, of Munich : There are many varieties of photo- typic processes, differing in minor opera- tions only. The autotype, albertype, and heliotype processes are photo'typic, and have been given different names to cover patents on details. The process as car- ried on by M. Obernetter gives most ex- cellent results, and is very simple in the- ory, and the half tints are obtained from the model to such a degree of perfection as to have the appearance of albumen proofs. The surface of a plate, either of glass or of metal, is covered with a film composed of 7 parts of albumen, 3 parts of silicate of soda, and 8 parts of water. This film is dried either in the air or by 91 artificial heat. When dry it is washed for about 5 minutes in clean water, and is again placed on a shelf to dry. When dry it is placed on a warm stove, and when it has arrived at a temperature of 100° it is covered with a second coating, composed of 50 grammes gelatine, 50 grammes isinglass, and 15 grammes bi- chromate of ammonia in a litre of water. As soon as this solution is equally spread over the surface of the plate it is placed in a stove to dry. When dry it is ex- posed under a negative for a very short time, and is then washed in water for 10 or 15 minutes until the superfluous salts of chromium and ammonia are washed out. As soon as dry it is ready for the press, and ordinary lithographic ink can be used. It is a cheap and rapid process, and gives very fine and very durable prints. Photo- Zincography. — This process in its simplest form is as follows : ' A zinc plate of uniform thickness is carefully pol- ished and cleaned. The face is then coated with a dilute solution of bitumen in ben- 92 zole, and is allowed to dry. It is then exposed under a negative. After suffi- cient exposure the soluble parts are washed out with turpentine, leaving the bare metal on the lines not acted on by the light. The plate is then slightly etched, to give the bitumen film a little greater relief ; it is then printed from, as in lithography. Major de La No'ie made the following alterations in the process : The plate is coated as described above, but is exposed under a drawing made on tracing paper. A longer time is neces- sary in the exposure, as the paper slight- ly impedes the passage of the actinic rays. After exposure the picture is de- veloped with turpentine, as above, and the plate is etched with a 5 per cent, so- lution of nitric acid for from ^ to f of a minute. It is then washed with w r ater and the remainder of the bitumen is washed off with benzole, and the plate is thoroughly cleaned. It is again coated with the bitumen solution, and the entire face exposed to the light. The etched portions become filled with the insoluble 93 solution, and the other portions must be removed. This is done mechanically by scouring the plate with a stick of hard- wood charcoal, ground to a beveled edge and moistened with oil. The etched parts still retain the bitumen, and the plate can be printed from as in lithog- raphy. The chemical process is as follows : The second coating of bitumen is worked with a roller, and exposed to the light. After exposure the soluble parts, viz., those that have taken the ink, are washed out with turpentine; the etched parts, being lower than the others, have re- ceived no ink. The plate is washed and printed from as before described. Calbon Pkixts. — The carbon process is an important one, and is extensively used, and I will go somewhat into details in describing it. A sheet of paper cov- ered with a gelatine " couche " and color- ing matter (generally India ink, from which the process derives its name) con- stitutes carbon paper. It is sensitized by immersion in a solution of bichromate 94 of potassium, and is suspended in a dark and well- aired chamber to dry. It is then exposed under the negative. As the progress of the image is not visible a photometer must be used to regulate the time of exposure. Two ways now present themselves for obtaining the image. 1st. By simple transfer, a process of wonderful simplicity, but which gives the image reversed, as regards right and left. 2d. Double transfer, which gives the image in a correct form, but which is more complicated in operation. Sensitizing of the Paper. — This opera- tion is very simple, but of great impor- tance, and the success of the subsequent operations depends upon its regularity. The sensitizing should be done in a dark room, with yellow or red lights ; the cu- vette, or dish containing the mixture should be of wood lined with glass, as the bichromate readily attacks wood or gutta-percha. Mix the following solu- tion : 95 Water . 10 liters, Bichromate of potassium . 200 grammes, Carbonate of ammonia. . 10 " The ordinary commercial bichromate may be used, but it should be finely pulver- ized. The mixture is poured into a flask, thoroughly shaken until the bichromate is dissolved ; it is then filtered and poured into the cuvette. One bath of bichromate should not be used for sensi- tizing too many sheets of the paper, as it is poor economy to compromise the results in order to save so cheap a mixture. Be- fore immersing the paper in the bath dust it carefully. Submerge the paper in the mixture, couche uppermost, and keep the liquid moving by rocking the cuvette. Keep the paper immersed for about 3 minutes, then remove it and re- immerse it for about one minute, the couche down, to work the adhering bub- bles from the back. After withdrawing, place it face down on an inclined glass plate ? and with a scraper work on the back, from the center towards the edges, until all of the excess of liquid is forced out ; then 96 detach the sheet from the glass and sus- pend it to dry. The bath should be kept at a temperature of about 15° C. Eubber gloves should be used while working with the bichromate, as it is a poison which acts . by absorption, and should be handled very carefully. If we wish to produce vigorous images with light negatives, the paper must be used the next morning after drying ; but if the negatives are strong it is better to wait 48 hours after the sensitizing before using it. Negatives for carbon prints ought to be a little more intense than for albumen paper. The edges of the nega- tive must be covered with yellow paper, so as to limit the cliche to the part to be reproduced, and the carbon paper must be cut so that its edges shall not pass the edges of the yellow paper which pro- tects the edges of the cliche ; it is then placed in the printing frame and ex- posed, and the time regulated by a photometer. The impression on carbon paper continues even after the action of the light has ceased; this is an import- 97 jgW^fa ant point to remember. Wye now come to the development and the simple trans- fer. Simple transfer paper is s £vr.epared in rolls exactly like carbon paper. It is covered with a couche of gelatine and chrome alum. Before using this paper it is well to mark the reverse side of it with a crayon, so it will be easily recog- nized in the subsequent operations- Transfer. — The transfer paper having been cut to dimensions a little greater than the proof it is immersed for two or three minutes in cold water ; it is then placed on a flat glass, or on a marble block, face up. The carbon proof is then immersed in cold water, buck up, rub- bing it with the hand so as to force out air bubbles. It is then placed on top of the transfer paper, face down, and the back is rubbed quickly and strongly with a scraper until the surfaces unite and the air bubbles and excess of water are forced out ; a dry sponge is a]so passed over the back and the edges of the paper. Development. — One ought never to 98 proceed to the development before the bichromate has taken hold of the trans- fer paper, which ought to become yellow in its texture, and which can be observed by looking at the underside. The devel- opment can be made in full light, indeed it ought to be done in the light, as it is necessary to judge of the condition of the image at all stages of development. The transfer paper, supporting the carbon paper, is now put into water at about 30° C, the cuvette being constantly shaken to favor the absorption of the warm water. After a few minutes dark-colored veins are seen on the edges of the proof, and soon the edges show a tendency to separate. Take the carbon paper by a corner and s]owly and carefully detach it from the transfer paper. The image will be seen transferred to the paper, which must be left in the warm water un- til the surplus coloring matter is washed out. The temperature of the water should be raised to about 40° C. by the addition of hot water. The image is formed by the gelatine in relief, and is 99 very fragile ; it should be immersed for 10 minutes in the following solution : This bath should be freshly made and filtered. The proofs are then immersed in water for an hour and are hung up 1 1 dry. After drying the proof is retouche:!, mounted, put. through the satin press, and varnished. Once dry, the imagj is of extreme solidity and durability. Double Tkansfer. — A flexible support i s especially prepared with the aid of simple transfer paper, which is covered with a varnish of (wax, 1 part ; warm benzine, 5 parts). The paper appears brilliant on the side which is to receive the transfer provisionally. The operations for the first transfer are in every way identical with those just described. When the image is raised from the water, after the development, it is placed on a thick glass, face up, and the operator immediately proceeds to the second transfer. The double trans- Water Pulverized alum. 5 liters, 250 grammes. 100 fer paper is covered with a couche of gelatine, rendered half insoluble by chrome alum. The paper is cut of a little larger dimension than the image, and is immersed in water at a temperature of 40° CL When the gelatine is a little softened remove the paper from the water, and place it carefully on top of the carbon image ; cover the back with a sheet of caoutchouc, and with a scraper work out the air bubbles and super- fluous moisture, and continue the opera- tion until the two papers form a homo- geneous sheet. Suspend this to dry in a chamber well aired and lightly warmed ; when dry insert a knife edge between the two papers, and detach them from one another, which is easily done. The image will be found on the paper which is to receive the final transfer ; it is mounted, retouched and varnished. Double Transfer with the aid of Glass. — Polished glass of from 4 to 5 millimeters in thickness is generally used for this purpose, and has this advantage: The condition of the image and the state 101 of the development can be observed through the glass* The glass is first thoroughly cleaned, and is coated with Yellow wax . <, . . . 1 gramme, Good benzine. . . 150 cuk cent, which is rubbed on the glass with a flan- nel rag and allowed to dry. After dry- ing, the surface may be polished by rub- bing it lightly with a dry flannel cloth* The coating of collodion, made as fol- lows : Ether ^ liter, Alcohol i " Pyroxyline 5 grammes, is then poured on the glass as prescribed in photography. The glass is dried, is well washed, and placed flat on a table, and the first transfer is made as described for the transfer paper. A sheet of caoutchouc should be interposed between the scraper and the carbon paper. In about 10 minutes after the transfer, one can proceed to the development, After the development the glass is placed for about five minutes in the alum bath, 102 which hardens the couehe. After it has dried make a mixture of immerse the proof in it for 3 or 4 min- utes. The alcohol takes the water from the gelatine and lowers the relief Then apply the double transfer paper, and pro- ceed as prescribed for the double trans- fer with the aid of paper. The retouch- ing can be done on the glass before the second transfer, if desired, and should be done with a mixture of red and black oil (tube) colors. If certain parts are want- ing they can be put in with a. stumpf and a rather dry mixture of lamp black and madder lake ; the satin finish is added as prescribed for albumen prints. Car- bon prints are very durable, and can be made so as to stand comparison with the best silver prints. It is best for be- ginners to work with the single transfer until some of the difficulties of the proc- ess are thoroughly mastered. The rough prints obtained by this- process have Alcohol Water . 103 much the appearance of phototypes. Beautiful transparencies are also made on glass by this process. WoODBURYTYPE, OR PHOTOGLYPH. This is an exceedingly ingenious process of obtaining a metallic mould from a gela- tine film, from which any number of copies may be printed. Potassium bi- chromate is mixed with gelatine, giving a highly sensitive mixture. A thick film of this, resting on collodion, is exposed under a negative to a strong light, the collodion side being placed next to the negative ; the usual action takes place ; the parts remaining soluble are washed out with warm water, leaving the darks of the picture wonderfully strong and hard. A sheet of soft metal, generally lead, is placed on this film and subjected to very strong pressure. On removal, a beautiful mould of the picture is found in the lead, the dark parts in intaglio, the lights in relief. A peculiar kind of gela- tinous ink, to which permanent dye or fine pigment may be added, is now poured on the mould, and the p>aper on which 104 the picture is to be printed is placed on it, and strong* pressure is brought to bear over the entire surface. This forces the gelatinous ink out of the lights which are in relief, and gives the half tones and darks by the varying thick- nesses of the gelatinous ink. The press- ure must be maintained for a few minutes, to allow the ink to set on the paper ; the paper is then immersed in a solution of alum, which renders the picture insoluble. The pictures made by this process are good, and wonderfully cheap. It can work with any color. The stannotype is the name given to the improved process of M. Woodbury. He makes use of a thin plate, tin, for the formation of the mould. His first im- jDrovement was the substitution of a fine tin plate for the leaden mould. The plate was fixed on the film and the back was strengthened by electrotypy. The prints were taken from the mould in ink composed of Gelatine 1 part, Water 5 or 6 parts, 105 Dark color A little red at pleasure, to give tone. He has endeavored, however, to still fur- ther simplify his process by using a posi- tive, from which a negative relief is formed. The fine tin is forced on this, and is made to adhere to the film by first giving it alight coating with caoutchouc. It is then only necessary to put the mould directly under the press and print from it without any further treatment. For fixing he uses the following solu- tion : Alum 1 part, Water 50 parts. Photogravure.' — The novelty and the secret of the photogravure consists in the particular means adopted for obtaining immediately in the gelatine the grain nec- essary to an engraving. To accomplish this M. Rousselon (for some time con- nected with the house of Goupiland Co.) incorporated in the gelatine a substance which produced this grain under the influence of the light, and in proportion 106 to the strength and duration of the light. By the Woodbury process this grain is reproduced in a leaden mould, and by the use of electrotypy a plate is obtained which is printed from as a copper plate engraving. A great deal depends on the skill of the manipulator, and with the as- sistance of the burin in touching up weak parts beautiful plates are produced. The process as now applied by M. Rousselon is very analogous to that used by M. Placet in the preparation of plates for heliogravures. The light is made to act through a negative on a bichromated gel- atine film ; the film is then immersed in water or in some liquid containing a con- tracting substance. The insoluble por- tions, viz., those acted upon by the light, cannot, like those surrounding them, ab- sorb water, and remain united ; they are raised up by the action of the water on the adjacent susceptible parts ; these swell out, and there results from this a contraction more or less strong accurate- ly following the action of the light. There results from this a roughened sur- 107 face, which, absent in the lights, extends gradually through all the tones up to the strong darks. This film is dried and separated from its provisional backing. It is submitted to strong pressure againt a thin sheet of tin or pewter, from which an electrotype is taken ; this is touched up by skilled hands, and magnificent prints are obtained from it. Another process, never made public, is believed to consist substantially of the following operations : A phototypic proof is transferred to a copper plate with sized India paper. It is then sprinkled with bitumen powder, so as to well cover the ink of the transfer ; it is then etched with the per-chloride of iron, and gives an engraved copper plate with all of the reliefs and depressions of the original. This last is pure chemical engraving, and as such is more subject to accidents than the mere mechanical one of M. Eousselon. This latter is the prince of " processes," and the artistic reproduc- tions exhibited by Messrs. Goupil & Co. have, to say the least, never been sur- 108 passed. Some chemical substance is added to the bichromated gelatine which gives to it, after exposure, development and drying, a^grain more or less marked following the strength of the shades in the picture. The remainder of the proc- ess is purely mechanical and is thorough- ly understood, and success is assured. After electrotyping, the plate is thor- oughly cleaned and proven, and re- touched with the burin, and the result is a finely-grained engraved plate, from which beautiful impressions are obtained, and which give even the details of the brush marks of the artist. The photo- gravure process of Major Waterhouse ar- rives at similar results. While the image formed by the gelatine is still moist he covers the surface with finely-divided sand, which has been covered with wax to prevent it from being retained by the gelatine after the development. The granulations produced by the sand are aiore or less deep, following the relief of bhe image. After the gelatine is dry the image is carefully cleaned with a brush* 109 and all the sand removed, leaving the grain marks in the gelatine. A mould of tje surface is then taken, and this is elec- trotyped and retouched. Photogravure Garnier. another process, the details of which have not been given to the public, has been invented by M. Garnier, and is believed to be as follows : A copper plate is covered with a film formed by dissolving sugar, gum, albu- men in water. This is sensitized by the addition of the following solution : Sugar 2 grammes, Bichromate of ammonia 1 " Water 14 This is exposed to the light under a posi- tive. The hygroscopic properties of the parts not acted upon by the light permit the adherence of finely-powdered bitu- men, which is sprinkled over the surface. The plate is then placed on a grating and heated until a faint iridescence is visible on the upper edge of the plate ; the plate is then etched with the per- chloride of iron, which eats out only the 110 parts not protected by the powdered bit- umen. For delicately graded half tints he repeats the process three times, using carefully-prepared reference points, stop- ping out the biting at pleasure. No re- touching is necessary, according to the inventor, but an intelligent touch is al- - ways of value. Heliographie and the Heliogravure. — The bitumen of Judea is generally used as the sensitive agent in heliographie processes. It should be of an especial quality. There are different substances of this nature, but the following solution is found to give the greatest resistance to the biting acid : Bitumen 3 to 5 grammes- Anhydrous benzine . 100 " Essence of lemon . . 2 to 5 drops. This mixture is poured on the metal as collodion is poured on glass. It is al- lowed to dry and is then exposed under the negative. The exposure complete d ? the insoluble parts are washed out with essence of lavender or essence of turpen- Ill tine, and the plate is subjected to the ac- tion of the acid . the naked parts, or the bare metal corresponding to the lights of the drawing, are "bitten" at the pleasure of the operator, and upon this the beauty of the work largely depends. After the first biting 5 which is continued until the en- graved parts are appreciable to the touch, the plate is placed on a lithographic press and coated with an inking of grey varnish, which naturally adheres only to the parts covered with the bitumen and already in relief. The plate is then warmed, and the varnish flows to the edges of the relief and gives an additional protection against the acid. A new biting takes place, and these same operations are continued until the operator judges the biting completed the bitumen is re- moved, the plate cleaned, the lines touched up with the burin, and the plate is ready for the press. During the suc- cessive operations the grey varnish, if placed artistically will stop out the action of the acid so as to give an exact repro- duction of the original. The oj>erations 112 are difficulty but do not compare with the difficulty of producing an engraved plate with the burin. By eleetrotyping, the converse of the plate may be obtained, making the process available for the pro- duction of plates either in high or in low relief. The bichromated gelatine film is used in a similar manner. After exposure the film is immersed in cold water, which causes the soluble portions of the gela- tine to swell out and form an image in relief ; a plaster cast of this is taken, and this is in turn electrotyped. The results of this process are not particularly good ; it is available for line work only, and the swelling of the gelatine cannot be re- lied upon for uniformity in relief. The invention and perfection of the processes for the production of helio- graphic plates is due to Scamoni, of St. Petersburg. With the assistance of elec- trotypy he produced excellent plates in high relief, a manifest advantage in the industrial arts, as engraved plates require a special paper> strong pressure, and 113 more time for each impression, whereas, plates in relief can be printed from in the rapid steam press used in typographic printing, and a much cheaper paper can be used. Of course this necessitates the sacrifice of a little of the fineness of the work to rapidity and economy. The plates are covered either with the mix- ture of gelatine and potass-dichromate or with the sensitive bitumen of Judea ; they are exposed under a positive ; they are then etched, which gives an engraved plate, and by electro typing this we get a plate in relief which can be printed from on an ordinary press. This was the process as invented by the Austrian, Pretsch, some years ago. Scamoni made the following changes : He ob- served that an ordinary photographic negative appears in relief, the transpa- rent places — -shadows — being hp. basso, and the lights in alto relievo ; this relief is very faint. He increased it by treat- ing the freshly developed image with py- rogallic acid and a solution of silver, and augmented it by a further treatment with 114 chloride of mercury and iodide of potas- sium. A relief was thus ultimately ob- tained equal to the depth of the incisions in an engraved copper plate ; by treating a positive in this manner all the means are at hand for obtaining an engraved plate. The relief-like photographic image is electrotyped, which gives low relief where the positive is in high re- lief, viz., in the darks of the original drawing, and we have an engraved cop- per plate. Most excellent maps can be produced by this process, with the origi- nal either enlarged or diminished. Scanioni reduced a page of an illustrated journal to a square inch, and the words could be plainly distinguished with the aid of a microscope. It is very probable that the beautiful maps of the Wheeler Survey were made by some modification of this process, which the Austrian Gov- ernment declines to make public. Aquatinte. — This is a species of en- graving with a peculiarly-prepared grain A plate of copper is first covered with a special gray varnish; the drawing is 115 made on this in outline, and, as in etch- ing, the bare parts of the metal are a bit- ten in " with acid. The varnish is then removed, the plate is cleaned and is placed in the graining box, which con- sists of a case in which, by mechanical means, a cloud of resinous powder can be raised. The powder is put in motion, and at an opportune moment the plate is placed in the box. A grain is thus de- posited on the surface of the plate, and this grain can be regulated by the time the plate is allowed to remain in the box. The operation can be renewed until the grain is more or less thick. The plate is then submitted to gentle warmth, which softens the resin and makes it adhere to the plate. When the desired "grainage" has been obtained the parts to remain white are covered with the gray varnish, and the biting acid is poured on the plate. It attacks only the places not covered with the resin nor with the varnish. By suc- cessive ' : bitings v and coatings with var- nish, the plate may be etched at the pleasure of the engraver, and the results 116 are more or less beautiful, depending upon his skill. A number of different processes have been invented by French scientists, based upon metallic precipitates and on the af- finities of acids for different metals. For example, a drawing made on zinc, with an ink formed of a salt of copper, permits the formation of a plate in relief by the action of azotic acid, the copper, in this case, playing the role of a protecting var- nish ; or, we might use a salt of mercury for copper, a salt of gold for silver, &c, and engrave with an appropriate acid. The following process has also been used : A plate of copper is silver plated ; the drawing is made on the silvered sur- face, or, better, is transferred to it, as, for instance, a drawing in ordinary litho- graphic ink. With the assistance of an electric battery a light coating of iron is formed on the surface of the plate, the deposit occurring only on the parts not covered with the ink. The ink is washed off with turpentine or benzine. The whites of the drawing are now repre- 117 sented by the iron, and the darks by the pure silver. The ammoniacal sul- phate of mercury is poured on the plate, and after the excess of the salt is brushed off the metal is seen in relief in all the parts previously covered with the lithographic ink. It is electrotyped, and we have an engraved copper plate. These processes are of doubtful value now, but they serve to illustrate the many resources that have been discovered and utilized by scientific men in the re- productions of drawings of various kinds. The ones just described were invented in 1864, and are quite modern. To sum up, it is well known that an amalgam of mercury with another metal repulses the greasy ink when the roller is passed over it, and the black ink ad- heres only to the naked metal. If then, we trace on, or transfer, a drawing in mercuric ink to a zinc plate well polished, it will appear in brilliant white lines on the gray back ground of the zinc. To obtain a plate in high relief it is only necessary to plunge the plate, without 118 the application of varnish or any stop, into the acid bath composed of 1 00 parts water to 2 parts of nitric acid. The biting takes place very rapidly, and the lines traced with the mercury soon stand out in relief, and can be printed from in a lithographic press. If, instead of plunging the plate into a nitric acid bath, we use a dilute solution of hydro- chloric acid, the reverse obtains, the lines are eaten away and we obtain an engraved plate in low relief. So far we have included only line drawings. To produce half tints the drawing is made on a very dense paper, and is transferred to the zinc plate by strong pressure for about two hours. By pulling off the paper the drawing will be seen in clean, white amalgam on the gray surface, and may be treated as before. An ink, con- taining sugar, gum, &c, in solution, may be used on the drawing ; on powdering this with a fine mercurial powder the same effects may be obtained ; the bi- iodide of mercury is the salt generally used. It is thought that these processes 119 are destined to become of great value in the graphic arts. The salts of mercury are violent poisons, and must be handled carefully : white of egg, sulphur-water and milk are antidotes. Similigkavure. — M. C. Petit has in- vented a process of engraving, having for its object the changing of the half tints of a photographic proof into line prints for the production of typographic blocks. The negative is placed over a bichro- mated gelatine film, and the image is de- veloped as in the autotype. A plastic material, such as hardened white wax, is pressed on the film, giving a counter proof of the gelatine ; this is placed under a line-drawing machine with a V-shaped cutting edge, and the wax is ruled with parallel lines, the depth being regulated by the operator. The surface of the wax having been covered with plumbago just after its removal from the gelatine, we now h^ve white lines on a black back- ground, the darks having been engraved more or less in proportion to the relief. From this wax mould a photographic 120 cliche is formed, and from this we get a typographic cliche, as explained for other processes. Gillotage . — M. Gillot has invented a process for obtaining a line negative, from which excellent typographic blocks can be produced. He takes a strong paper and covers it with a white glazing ; then, with a prepared plate, he prints a series of parallel dark lines on the glazed paper, giving about three lines to the millimeter. A steel plate is then put un- der a line-engraving machine, and a series of parallel lines, corresponding to those on the paper, are cut into the plate to the depth of about ^ of a millimeter. The paper is then pressed on this plate so as to give two series of lines at right angles with each other, one series being the dark lines drawn on the paper, the other, the fine creases formed by the relief parts of the plate. The paper is now ready for the drawing; the pure whites are smoothed down with a scraper, so as to make the creases disappear, and the dark lines are erased ; for the half 121 tints lie relies on the handling of the crayon, for the full darks the creases are filled with India ink; a negative is taken from this. A zinc plate is cov- ered with a thin coating of the sensitive bitumen, and from this especially pre- pared negative, a relief plate is obtained, with the half tones excellently well ren - dered, as the negative gives them in se- ries of lines, which are much more readi- ly handled and transferred than the or- dinary dotted half tints. Luxotype. — This process aims at the production of "grained" negatives by a treatment with powdered glass or other finely divided material. It is very new, and is not made public. Its inventors claim that it is photo typographic, and that they can produce blocks very cheaply, from which good impressions can be taken in the ordinary printing press working with great rapidity. I saw several prints in a journal of photog- raphy. They were printed on text-paper, and had the appearance of very delicately executed wood cuts. 122 Beproduction of Polychromes. — We have thus far been interested only in processes for the reproduction of mono- chromes. The great and constantly in- creasing demand for copies of the many beautiful paintings old and new, true in color and in chiaro-oscuro ; the still greater demands of the industrial arts for high grade work in colors are stimu- lating invention and taxing the abilities of men engaged in this work. The chro- mo-lithographic processes have attained a high degree of perfection, and the beauti- ful prints of Messrs. Prang & Co. on satin and on paper have never been sur- passed in tone or finish. A skillful artist can paint on stone as he would on can- vas, but with this difference, in working on stone he sees the results only in his imagination and must wait for a proof. In canvas the immediate results are in- cessantly under his eye. The discovery of a means of photographing color has been announced at stated intervals, but investigation has revealed the fact that the color has been introduced in the 123 printing, and was not found in tli£ tive. Many years \mve been devoted efforts to obtam a plate from which number of colors can be printed by a single pressure. The process of steno- chromie promises a great deal, but for some unknown reason it has not entirely succeeded. It is briefly as follows : Pieces of color for each tint on the drawing ars carefully adjusted to their places on paper, so as to constitute a mosaic tracing in paint on the paper. The unsized paper which is to receive the print is impreg- nated with the essence of turpentine ; it is then pressed on the colors, and a su- perficial dissolution of them takes place, and the paper is removed carrying tin im- print of the colors which constituted the stenochromic block. It is thought that the expense attending it has prevented its adoption. The Bonnaudtype process for coloring photographs is used in New York to some extent, and is as follows : A feeble proof of the negative is taken, so as to have an indication of the various places occu- 124 pied by the colors. When the colors have been applied a very light impres- sion is taken on sensitized paper, a very light image is developed on this, and is fixed and washed as usual, and after dry- ing it is immersed for 2 or 3 seconds in rectified alcohol. When this liquid has evaporated the proof is run through the press for polishing. It is then colored with a brush, using vegetable colors. After the coloring is terminated it is again passed through the polishing press ; it is than immersed in rectified alcohol, and lastly the surface is albuminized. An inking apparatus has been invented by J. L. F. Eice, of Cambridge, Mass., which can be attached to our ordinary printing press, and any desired number of colors can be printed at one impres- sion, but only in bands or stripes. Conclusion. — I have endeavored to give brief outlines of the various proc- esses of reproduction in use to-day. It will be readily seen that constant study by a large number of inventors and scientific men has resulted in a series of 125 processes and patents so nur so closely allied, that it is d3 classify them. Many of the patents have fallen into the public domain, and have been rendered of practical rise in in- dustry. The details of others are strictly guarded secrets. They are all beyond the reach of amateurs, and require much skill and knowledge in the operations. Advantages are claimed for each process, and excellent specimens of each can be shown. We are principally interested in the reproduction of maps and of mechan- ical and architectural drawings ; sensitive papers, the hextograph and photography are within our reach. Experiments with any of the other processes would result in many signal failures. For contract work, requiring rapidity, economy and excellence, we have nothing better than the various processes of lithography. We have many good lithographing es- tablishments. Prices are moderate, and the work excellent. Combined with chromo -lithography and photo-lithog- raphy it is very wide in range. Thousands 126 of copies can be obtained from one lithographic transfer. One establishment at Berlin produced 500,000 maps during war of 1870-71. For the selection of a method for the reproduction of any work, we must be guided by three things, viz., the cost, the rapidity with which the work can be ex- ecuted, and its durability. The proc- esses are sufficiently numerous, and are rich enough in results to meet any de- sired requirements. They are daily reaching higher grades of development, and beautiful pictures are being brought within the reach of all classes. The ten- dency of the day is undoubtedly towards the invention and perfection of typo- raphic processes, but I Ihink that I am safe in saying that a typographic block can never be made to give the beauty and brilliancy and the pureness of line obtained from engraved plates. This is clearly illustrated in the two processes for the production of heliogravures. Many skilled men are engaged in the re- production of artistic works, and it is to 127 their genius and artistic taste that we owe our homage for the many beautiful things brought within our reach and made available for home decorations, for by delicacy of handling, and quick ap- preciation of the possibilities in chem- istry, light and mechanics, they have made the latter subservient to the artis- tic tastes of mankind. Y* Any book in this Catalogue sent free by mail on receipt of price* VALUABLE SCIENTIFIC BOOKS PUBLISHED BY D. VAN NOSTRAND, 23 Murray Street and 27 Warren Street, N. Y. ADAMS (J. W.) Sewers and Drains for Populous Districts. Embracing- Rules and Formulas lor the dimensions and construction of works of Sanitary Engineers. Second edi- tion. 8vo, cloth $2 50 ALEXANDER (J. H.) Universal Dictionary of Weights and -Measures, Ancient and Modern, reduced to the standards of the United States of America. New edition, enlarged. 8vo, cloth 3 e^o ATWOOD(GEO.) Practical Blow-Pipe Assaying, rnno, cloth, illustrated 2 00 AUCHINCLOSS (W. S.) Link and Valve Motions Simplified. Illustrated with 37 wood-cuts and 21 lithographic plates, together with a Travel Scale and numerous useful tables. 8vo, cloth 3 00 AXON (W E. A.) The Mechanic's Friend : a Collection of Re- ceipts and Practical Suggestions Relating to Aquaria — Bronzing— Cements— Drawing— Dyes— Electricity— Gilding —Glass-working — Glues — Horology — Lacquers— Locomo- tives — Magnetism — Metal-working - Modelling — Photogra- phy— Pyrotechny— Railways— Solders— Steam-Engine— Tel- egraphy— Taxidermy— Varnishes— Waterproofing, and Mis- cellaneous Tools, Instruments, Machines, and Processes connected with tne Chemical and Mechanic Arts. With nu- merous diagrams and wood-cuts. Fancy cloth I 50 BACON (F. W.) A Treatise on the Richards Steam-Engine Indicator, with directions for its use. By Charles T. Por- ter. Revised, with notes and large additions as developed by American practice ; with an appendix containing useful formulae and rules for engineers. Illustrated. Third edi- tion. i2mo, cloth I 00 2 D. VAN NOSTRAND'S PUBLICATIONS. BARBA (J.) The Use of Steel for Constructive Purposes ; Method of Working, Applying, and Testing Plates and Brass. With a Preface by A. L. Holley, C.E. i2mo, cloth. §i 50 BARNES (Lt. Com. J. S., U. S. N.) Submarine Wariare, offen- sive and defensive, including a discussion of the offensive Torpedo System, its effects upon Iron-Clad Ship Systems and influence upon future naval wars. With twenty litho- graphic plates and many wood-cuts. 8vo, cloth 5 00 BEILSTEIN (F.) An Introduction to Qualitative Chemical Analysis, translated by I. J. Osbun. i2mo, cloth 75 BENET (Gen. S. V., U. S. A.) Electro-Ballistic Machines, and the Schultz Chronoscope. Illustrated. Second edition, 4to, cloth 3 00 BLAKE (W. P.) Report upon the Precious Metals : Being Sta- tistical Notices of the principal Gold and Silver producing regions of the World., represented at the Paris Universe' Exposition. 8vo, cloth 2 00 Ceramic Art. A Report on Pottery, Porcelain, Tiles, Terra Cotta, and Brick. 8vo, cloth 200 BOW (R. H.) A Treatise on Bracing, with its application to Bridges and other Structures of Wood or Iron. 156 illustra- tions. 8vo, cloth 1 50 BOWSER (Prof. E. A.) An Elementary Treatise on Analytic Geometry, embracing Plane Geometry, and an Introduc- tion to Geometry of three Dimensions. i2mo, cloth 1 75 An Elementary Treatise on the Diffen-ntial and Integral Calculus. With numerous examples. i2mo, cloth 225 BURGH (N. P.) Modern Marine Engineering, applied to Pad- dle and Screw Propulsion. Consisting of 36 colored plates, 259 practical wood-cut illustrations, and 403 pages of de- scriptive matter, the whole being an exposition of the pre- sent practice of James Watt & Co., J. & G. Rennie, R. Na- pier & Sons, and other celebrated firms. Thick 4to vol., cloth 10 00 Half morocco 15 00 BURT (W. A.) Key to the Solar Compass, and Surveyor's Com- panion ; comprising all the rules necessary for use in the field ; also description of the Linear Surveys and Public Land System of the United States, Notes on the Barome- ter, suggestions for an outfit for a survey of four months, etc. Second edition. Pocket-book form, tuck 2 50 BUTLER (Capt. J. S., U. S. A.) Projectiles and Rifled Cannon. A Critical Discussion of the Principal Systems of Rifling and Projectiles, with Practical Suggestions for their Im- provement, as embraced in a Report to the Chief of Old- nance, U. S. A. 36 plates. 4to, cloth..'. 6 00 D. VAN NOSTRAND'S PUBLICATIONS. 3 C a I :\ T {Prof. WM .) A Practical Treatise on Voussoir and Solid and Braced Arches. i6mo, cloth extra $i 75 CALDWELL (Prof. GEO. C.) and BRENEMAN (Prof. A. A.) Manual of Introductory Chemical Practice, for the use of Students in Colleges and Normal and High Schools. Third edicion, revised and corrected. 8vo, cloth, illustrated. New and enlarged coition. . I 50 CAMPIN (FRANCIS). On the Construction of Iron Roofs. 8vo, with plates, cloth 2 00 CHAUVENET (Prof. W.) New method of correcting Lunar Distances, and improved method of finding the error and rate of a chronometer, by equal altitudes. 8vo, cloth 200 CHURCH (JOHN A.) Notes of a Metallurgical Journey in Europe. 8vo, cloth 2 00 CLARK (D. KINNEAR, C.E.) Fuel: Its Combustion and Economy, consisting of Abridgments of Treatise on the Combustion of Coal and the Prevention of Smoke, by C. W. Williams; and the Economy of Fuel, by T. S. Pri- deaux. With extensive additions on recent practice in the Combustion and Economy of Fuel: Coal, Coke, Wood, Peat, Petroleum, etc. i2mo, cloth I 50 A Manual of Rules, Tables, and Data for Mechanical Engineers. Based on the most recent investigations. Illus- trated with numerous diagrams. 1,012 pages. 8vo, cloth. .. 7 50 Half morocco 10 00 CLARK (Lt. LEWIS, U. S. N ) Theoretical Navigation and Nautical Astronomy. Illustrated with 41 wood-cuts. 8vo, cloth 1 50 CLARKE (T. C.) Description of the Iron Railway Bridge over the Mississippi River at Quincy, Illinois. Illustrated with 21 lithographed plans. 4to, cloth 7 50 CLEVENGER (S. R.) A Treatise on the Method of Govern- ment Surveying, as prescribed by the U. S. Congress and Commissioner of the General Land Office, with complete Mathematical, Astronomical, and Practical Instructions for the use of the United States Surveyors in the field. l6mo, morocco 2 50 COFFIN (Prof. J. H. C ) Navigation and Nautical Astrono- my. Prepared for the use of the U. S. Naval Academy. Sixth edition. 52 wood-cut illustrations. i2mo, cloth 3 50 COLBURN (ZERAH). The Gas-Works of London. i2tno, boards 60 COLLINS (J AS. E.) The Private Book of Useful Alloys and Memoranda for Goldsmiths, Jewellers^ etc. i8mo, cloth.. . 50 4 D. VAN NOSTRAND'S PUBLICATIONS. CORNWALL (Prof. H. B.) Manual of Blow Pipe Analysis, Qualitative and Quantitative, with a Complete System of Descriptive Mineralogy. 8vo, cloth, with many illustra- tions. N. Y., 1882 $2 50 CRAIG (B.F.) Weights and Measures. An account of the Decimal System, with Tables of Conversion for Commer- cial and Scientific Uses. Square 32m©, limp cloth 50 CRAIG (Prof. THOS.) Elements of the Mathematical Theory of Fluid Motion. i6mo, cloth I 25 DAVIS (C. B.) and RAE (F. B.) Hand-Book of Electrical Dia- grams and Connections. Illustrated with 32 full-page illus- trations. Second edition. Oblong 8vo, cloth extra 200 DIEDRICH (JOHN). The Theory of Strains : a Compendium for the Calculation and Construction of Bridges, Roofs, and Cranes. Illustrated by numerous plates and diagrams. 8vo, cloth 5 00 DIXON (D. B.) The Machinist's and Steam-Engineer's Prac- tical Calculator. A Compilation of useful Rules, and Prob- lems Arithmetically Solved, together with General Informa- tion applicable to Shop-Tools, Mill-Gearing, Pulleys and Shafts, Steam-Boilers and Engines. Embracing Valuable Tables, and Instruction in Screw-cutting, Valve and Link Motion, etc. i6mo, full morocco, pocket form . . .(In press) DODD (GEO.) Dictionary of Manufactures, Mining, Ma- chinery, and the Industrial Arts. i2mo, cloth 1 50 DOUGLASS (Prof. S. H.) and PRESCOTT (Prof. A. B.) Qual- itative Chemical Analysis. A Guide in the Practical Study of Chemistry, and in the Work of Analysis. Third edition. 8vo, cloth 3 50 DUBOIS (A. J.) The New Method of Graphical Statics. With 60 illustrations. 8vo, cloth 1 ^o EASSIE (P. B.) Wood and its Uses. A Hand-Book for the use of Contractors, Builders, Architects, Engineers, and Tim- ber Merchants. Upwards of 250 illustrations. 8vo, cloth. 150 EDDY (Prof. H. T.) Researches in Graphical Statics, embrac- ing New Constructions in Graphical Statics, a New General Method in Graphical Statics, and the Theory of Internal Stress in Graphical Statics. 8vo, cloth 1 50 ELIOT (Prof. C. W.) and STORER (Prof. F. H.) A Compen- dious Manual of Qualitative Chemical Analysis. Revised with the co-operation of the authors. By Prof. William R. Nichols. Illustrated. i2mo, cloth 1 50 ELLIOT (Maj. GEO. H., U. S. E.) European Light-House Systems. Being a Report of a Tour of Inspection made in 1873. 51 engravings and 21 wood-cuts. 8vo, cloth 5 00 D. VAN NOSTRAND'S PUBLICATIONS. 5 ENGINEERING FACTS AND FIGURES. An Annual Register of Progress in Mechanical Engineering and Con- struction for the y«ars 1863-64-65-66-67-68. Fully illus- trated. 6 vols. i8mu, cloth (each volume sold separately), per vol $2 50 FANNING (J. T.) A Practical Treatise of Water-Supply En- gineering. Relating to the Hydrology, Hydrodynamics, and Practical Construction of Water-Works in North America. Third edition. With numerous tables and 180 illustra- tions. 650 pages. 8vo, cloth 500 FISKE (BRADLEY A., U.S. N.) Electricity in Theory and Practice. 8vo, cloth 2 50 FOSTER (Gen. J. G., U- S. A ) Submarine Blasting in Boston Harbor, Massachusetts Removal of Tower and Ccrwin Rocks. Illustrated with seven plates. 410, cloth 3 50 FOYE (Prof. J. C.) Chemical Problems. With brief State- ments of the Principles involved. Second edition, revised and enlarged. i6mo, boards 50 FRANCIS (JAS. B., C E.) Lowell Hydraulic Experiments: Being a selection from Experiments on Hydraulic Motors, on the Flow of Water over Weirs, in Open Canals of Uni- form Rectangular Section, and through submerged Orifices and diverging Tubes. Made at Lowell, Massachusetts. Fourth edition, revised and enlarged, with many new ex- periments, and illustrated with twenty-three copperplate engravings. 4to, cloth 15 00 FREE-KAND DRAWING. A Guide to Ornamental Figure and Landscape Drawing. By an Art Student, i8mo, boards 50 GILLMORE (Gen. Q. A.) Treatise on Limes, Hydraulic Ce- ments, and Mortars. Papers on Practical Engineering, U. S. Engineer Department, No. 9, containing Reports of numerous Experiments conducced in New York City during the years 1858 to 1861, inclusive. With numerous illustra- tions. 8vo, cloth 4 00 Practical Treatise on the Construction of Roads, Streets, and Pavements. With 70 illustrations. i2mo, cloth 2 00 Report on Strength of the Building Stones in the United States, etc. 8vo, illustrated, cloth 1 50 Coignet Beton and other Artificial Stone. 9 plates, views, etc. dvo, cloth 2 50 GOODEVE (T. M.) A Text-Book on the Steam-Engine. 143 illustrations. Kir.o, cloth 2 00 GORDON (J. E. H.) Four Lectures on Static Induction. i2mo, cloth So 6 D. VAN NOSTRAND'S PUBLICATIONS. GRUNER (M. L.) The Manufacture of Steel. Translated from the French, by Lenox Smith, w ith an appendix on the Bessemer process in the United States, by the translator. Illustrated. 8vo, cloth $3 50 HALF-HOURS WITH MODERN SCIENTISTS. Lectures and Essays. By Professors Huxley, Barker, Stirling, Cope, Tyndall, Wallace, Roscoe, Huggins, Lockyer, Young, Mayer, and Reed. Being the University Series bound up. With a general introduction by Noah Porter, President of Yale College. 2 vols. i2mo, cloth, illustrated 2 so HAMILTON (W. G.) Useful Information for Railway Men. Sixth edition, revised and enlarged. 562 pages, pocket form. Morocco, gilt 2 00 HARRISON (W. B.) The Mechanic's Tool Book, with Prac- tical Rules and Suggestions for Use of Machinists, Iron- Workers, and others. Illustrated with 44 engravings. i2mo, cloth 1 50 HASKINS (C. H.) The Galvanometer and its Uses. A Man- ual for Electricians and Students. Second edition. i2mo, morocco 1 50 HENRICI (OLAUS). Skeleton Structures, especially in their application to the Building of Steel and Iron Bridges. With folding plates and diagrams. 8vo, cloth 1 50 HEWSON (WM.) Principles and Practice of Embanking Lands from River Floods, as applied to the Levees of the Mississippi. 8vo, cloth 2 00 HOLLEY (ALEX. L.) ATreatiseon Ordnance and Armor, em- bracing descriptions, discussions, and professional opinions concerning the materials, fabrication, requirements, capa- bilities, and endurance of European and American Guns, for Naval, Sea-Coast, and Iron-Clad Warfare, and their Rifling, Projectiles, and Breech-Loading; also, results of experiments against armor, from official records, with an appendix referring to Gun-Cotton, Hooped Guns, etc., etc. 948 pages, 493 engravings, and 147 Tables of Results, etc. 8vo, half roan 10 00 — Railway Practice. American and European Railway- Practice in the economical Generation of Steam, including the Materials and Construction of Coal-burning Boilers, Combustion, the Variable Blast, Vaporization, Circulation, Superheating, Supplying and Heating Feed-ws.ter, etc., and the Adaptation of Wood and Coke-burning Engines to Coal-burning ; and in Permanent Way, including Road-bed, Sleepers, Rails, Joint-fastenings, Street Railways, etc., etc. With 77 lithographed plates. Folio, cloth 12 00 HOWARD (C. R.) Earthwork Mensuration on the Basis of the Prismoidal Formulae. Containing simple and labor- saving method of obtaining Prismoidal Contents directly D. VAN NOSTRAND'S PUBLICATIONS. from End Areas. Illustrated by Examples, and accom- panied by Plain Rules for Practical Uses. Illustrated. 8vo, cloth $1 50 INDUCTION-COILS. How Made and How Used. 63 illus- trations. i6mo, boards 50 ISHERWOOD (B. F.) Engineering Precedents for Steam Ma- chinery. Arranged in the most practical and useful manner for Engineers, With illustrations- Two volumes in one. 8vo, cloth 2 50 JANNETTAZ (EDWARD). A Guide to the Determination of Rocks: being an Introduction to Lithology. Translated from the French by G. W. Plympton, Professor of Physical Science at Brooklyn Polytechnic Institute. i2mo, cloth 1 50 JEFFERS (Capt. W. N., U. S. N.) Nautical Surveying. Illus- trated with 9 copperplates and 31 wood-cut illustrations. 8vo, cloth , 5 00 JONES (H. CHAPMAN). Text-Book of Experimental Or- ganic Chemistry for Students. i8mo, cloth . . 1 00 JOYNSON (F. H.) The Metals used in Construction: Iron, Steel, Bessemer Metal, etc., etc. Illustrated. i2mo, cloth. 75 Designing and Construction of Machine Gearing. Illus- trated. 8vo, cloth 2 00 KANSAS CITY BRIDGE (THE). With an account of the Regimen of the Missouri River, and a description of the methods used for Founding in that River. By O. Chanute, Chief-Engineer, and George Morrison, Assistant-Engineer. Illustrated with five lithographic views and twelve plates of plans. 4to, cloth 6 00 KING (W. H.) Lessons and Practical Notes on Steam, the Steam-Engine, PropeHers, etc., etc , for young Marine En- gineers, Students, and others. Revised by Chief-Engineer J. W. King, U. S. Navy. Nineteenth edition, enlarged. 8vo, cloth 2 00 KIRKWOOD (JAS. P.) Report on the Filtration of River Waters for the supply of Cities, as practised in Europe, made to the Board of Water Commissioners of the City of St. Louis. Illustrated by 30 double-plate engravings. 4to, cloth 15 00 LARRABEE (C. S.) Cipher and Secret Letter and Telegra- phic Code, with Hogg's Improvements. The most perfect secret code ever invented or discovered. Impossible to read without the key. i8mo, cloth I 00 LOCK (C. G.), WIGNER (G. W), and HARLAND (R. H.) Sunrar Growing and Kefining. Treatise on the Culture of Sugar-Yielding Plants, and the Manufacture and Refining of Cane, Beet, and other sugars. 8vo, cloth, illustrated 12 oo 8 D. VAN NOSTRAND'S PUBLICATIONS. LOCKWOOD (THOS. D.) Electricity, Magnetism, and Elec- tro-Telegraphy. A Practical Guide for Students, Operators, and Inspectors. 8vo, cloth.. . . . §2 50 LORING (A. E.) A Hand-Book on the Electro-Magnetic Tele- graph. Paper boards o 50 Cloth 75 Morocco I 00 MacCORD (Prof. C. W ) A Practical Treatise on the Slide- Valve by Eccentrics, examining by methods the action of the Eccentric upon the Slide-Valve, and explaining the prac- tical processes of laying out the movements, adapting the valve for its various duties in the steam-engine. Second edi- tion. Hlustrated. 4to, cloth 2 50 McCULLOCH (Prof. R. S.) Elementary Treatise on the Me- chanical Theory of Heat, and its application to Air and Steam Engines. 8vo, cloth 3 50 MERRILL (Col. WM. E., U. S. A.) Iron Truss Fridges for Railroads. The method of calculating strains in Trusses, with a careful comparison of the most prominent Trusses, in reference to economy in combination, etc., etc. Illustrated, 4to, cloth 5 00 MICHAELIS (Capt. O. E., U. S. A.) The Le Boulenge Chronograph, with three lithograph folding plates of illus- trations. 4to, cloth 300 MICHIE (Prof. P. S.) Elements ot Wave Motion relating to Sound and Light. Text-Hook for the U.S. Military Acade- my. 8vo, cloth, illustrated. . . 5 00 MINIFIE (WM.) _ Mechanical Drawing. A Text-Rook of Geo- metrical Drawing for the use of Mechanics and Schools, in which the Definitions and Rules of Geometry are familiarly explained ; the Practical Problems are arranged, from the most simple to the more complex, and in their description technicalities are avoided as much as possible. With illus- trations for Drawing Plans, Sections, and Elevations of Railways and Machinery ? an Introduction to Isometrica? Drawing, and an Essayon Linear Perspective and Shadows. Illustrated with over 200 diagrams engraved on steei. Ninth edition. With an Appendix on the Theory and Application of Colors. 8vo, cloth 4 00 u It is the best work on Drawing that we have ever seen, and is especially a text-book of Geometrical Drawing for the use of Me- chanics and Schools. No young Mechanic, such as a Machinist,, Engineer, Cabinet-maker, Millwright, or Carpenter, should be with- out it." — Scientific American. Geometrical Drawing. Abridered from the octavo edi- N tion, for the use of schools. Illustrated with forty-eight steel plates. Fifth edition, iamo* cloth. 2. 00 D. VAN NOSTRAND'S PUBLICATIONS. 9 MODERN METEOROLOGY. A Series of Six Lectures, de- livered under the auspices of the Meteorological Society in 1878. Illustrated. i2mo, cloth $1 50 MORRIS (E.) Easy Rules for the Measurement of Earth- works, by Means of the Prismoidal Formula. 78 illustra- tions. 8vo, cloth 1 5° MOTT (H. A., Jr.) A Practical Treatise on Chemistry (Quali- tative and Quantitative Analysis), Stoichiometry, Blow-pipe Analysis, Mineralogy, Assaving, Pharmaceutical^ Prepara- tions, Human Secretions, Specific Gravities, Weights and Measures, etc., etc., etc. New edition, 1883. 650 pages. 8vo, cloth 4 00 NAQUET (A.) Legal Chemistry. A Guide to the Detection of Poisons, Falsification of Writings, Adulteration of Alimen- tary and Pharmaceutical Substances, Analysis of Ashes, and examination of Hair, Coins, Arms, and Stains, as ap- plied to Chemical Jurisprudence, for the use of Chemists, Physicians, Lawyers, Pharmacists, and Experts. Translat- ed, with additions, including a list of books and Memoirs on Toxicology, etc., from the French. By J. P. Battershall, Ph.D., with a preface by C. F. Chandler, Ph.D., M.D., LL.D. i2mo, cloth 2 00 NOBLE (W.H.) Useful Tables. Pocket form, cloth so NUGENT (E.) Treatise on Optics ; or, Light and Sight, theo- retically and practically treated, with the application to Fine Art and Industrial Pursuits. With 103 illustrations i2mo, cloth 1 c;o PEIRCE (B.) System of Analytic Mechanics. 4to, cloth 10 00 PLANE TABLE (THE). Its Uses in Topographical Survey- ing. From the Papers of the U. S. Coast Survey. Illustrat- ed. 8vo, cloth • 2 00 " This work gives a description of the Plane Table employed at the U. S. Coast Survey office, and the manner of using it." PLATTNER. Manual of Qualitative and Quantitative An- alysis with the Blow-Pipe. From the last German edition, revised and enlarged. By Prof. Th. Richter, of the Roval Saxon Mining Academy. Translated by Prof H. B. Corn- wall, assisted by John H.Caswell. Illustrated with 87 wood- cuts and one lithographic plate. Fourth edition, revised, 560 pages. 8vo, cloth 500 PLYMPTON (Prof. GEO. W.) The Blow-Pipe. A Guide to its use in the Determination of Salts and Minerals. Compiled from various sources. i2mo, cloth 1 50 The Aneroid Barometer: Its Construction and Use. Compiled from several sources. i6mo, boards, illustrated, 50 Morocco 1 00 10 D. VAN NOSTRAND'S PUBLICATIONS. PLYMPTON (Prof. GEO. W.) The Star-Finder, or Plani- sphere, with Movable Horizon. Printed in colors on fine card-board, and in accordance with Proctor's Star Atlas. . .$roo POCKET LOGARITHMS, to Four Places of Decimals, includ- ing Logarithms of Numbers, and Logarithmic Sines and Tangents to Single Minutes. To which is added a Table of Natural Sines, Tangents, and Co-Tangents. i6mo, boards, 50 Morocco 1 60 POOK (S. M.) Method of Comparing the Lines and Draught- ing Vessels propelled by Sail or Steam. Including a chap- ter on Laying-on on the Mould-Loft Floor. 1 vol. 8vo, with illustrations, cloth 5 00 POPE (F. L.) Modern Practice of the Electric Telegraph. A Hand-Book for Electricians and Operators. Eleventh edi- tion, revised and enlarged, and fully illustrated. 8vo, cloth. 2 00 PRESCOTT (Prof. A. B.) Outlines of Proximate Organic An- alysis, for the Identification, Separation, and Quantitative Determination of the more commonly occurring Organic Compounds. i2mo, cloth 1 75 Chemical Examination of Alcoholic Liquors. A Manual of the Constituents of the Distilled Spirits and Fermented Liquors of Commerce, and their Qualitative and Quantita- tive Determinations. i2mo, cloth 1 50 First Book in Qualitative Chemistry. Second edition. i2mo, cloth 1 50 PYNCHON (Prof. T. R.) Introduction to Chemical Physics, designed for the use of Academies, Colleges, and High- Schools. Illustrated with numerous engravings, and con- taining copious experiments with directions for preparing them. New edition, revised and enlarged, and illustrated by 269 illustrations on wood Crown 8vo, cloth 3 00 RAMMELSBERG (C. F.) Guide to a Course of Quantitative Chemical Analysis, especially of Minerals and Furnace Pro- ducts. Illustrated by Examples. Translated by J. Towler, M.D. 8vo, cloth 2 25 RANDALL (P. M.) Quartz Operator's Hand-Book. New edi- tion, revised and enlarged, fully illustrated. i2mo, cloth.. . 2 00 RANKINE (W.J. M.) Applied Mechanics, comprising Prin- ciples of Statics, Cinematics, and Dynamics, and Theory ot Structures, Mechanism, and Machines. Crown 8vo, cloth. Tenth edition. London 5 00 A Manual of the Steam-Engine and other Prime Movers, with numerous tables and illustrations. Crown 8vo, cloth. Tenth edition. London, 1882 5 00 A Selection from the Miscellaneous Scientific Papers of, with Memoir by P. G. Tait, and edited by W.J. Millar, C.E. 8vo, cloth. London, 1880 10 00 D. VAN NOSTRAND'S PUBLICATIONS. 11 RANKINE (W. J. M.) A Manual of Machinery and Mill-work. Fourth edition. Crowa 8vo. London, 1881 .... $500 Civil Engineering, comprising Engineering Surveys, Earthwork, Foundations, Masonry, Carpentry, Metal- works, Roads, Railways, Canals, Rivers, Water-works, Harbors, etc., with numerous tables and illustrations. Fourteenth edition, revised by E. F. Bamber, C.E. 8vo. London, 1883 6 50 Useful Rules and Tables for Architects, Builders, Car- penters, Coachbuilders, Engineers, Founders, Mechan- ics, Shipbuilders, Surveyors, Typefounders, Wheelwrights, etc. Sixth edition. Crown 8vo, cloth. London, 1883 4 00 and BAMBER (E. F.) A Mechanical Text-Book ; or, Introduction to the Study of Mechanics and Engineering. 8vo, cloth. London, 1875 3 $0 RICE (Prof. J. M.) and JOHNSON (Prof. W. W.) On a New Method of Obtaining the Differentials of Functions, with especial reference to the Newtonian Conception of Rates or Velocities. i2mo, paper 50 ROGERS (Prof. H. D.) The Geology of Pennsylvania. A Gov- ernment Survey, with a General View of the Geology of the United States, Essays on the Coal Formation and its Fos- sils, and a description of the Coal F ields of Noith America and Great Britain. Illustrated with Plates and Engravings in the text. 3 vols. 4to, cloth, with Portfolio of Maps 30 00 ROEBLING (J. A.) Long and Short Span Railway Bridges. Illustrated with large copperplate engravings of plans and views. Imperial folio, cloth 25 00 ROSE (JOSHUA, M.E.) The Pattern-Maker's Assistant, em- bracing Lathe Work, Branch Work Core Work, Sweep Work, and Practical Gear Constructions, the Preparation and Use of Tools, together with a large collection of useful and val- uable Tables. Third edition. Illustrated with 250 engrav- ings. 8vo, cloth 2 50 SABINE (ROBERT). History and Progress of the Electric Tel- egraph, with descriptions of some of the apparatus. Second edition, with additions, i2mo, cloth 1 25 SAELTZER(ALEX ) Treatise on Acoustics in connection with Ventilation. i2mo, cloth I 00 SCHUMANN (F.) A Manual of Heating and Ventilation in its Practical Application for the use of Engineers and Archi- tects, embracing a series ot Tables and Formulae for dimen- sions of heating, flow and return pipes for steam and hot- water boilers, flues, etc., etc. i2mo. Illustrated. Full roan 1 50 Formulas and Tables for Architects and Engineers in calculating the strains and capacity of structures in Iron and Wood. i2mo, morocco, tucks 2 50 12 D. VAN NOSTRAND'S PUBLICATIONS. SAWYER (W. E.) Electric-Lighting by Incandescence, and its Application to Interior Illumination. A Practical Treatise. With 96 illustrations. Third edition. 8 vo, cloth. $2 50 SCRIBNER (J. M.) Engineers' and Mechanics' Companion, comprising United States Weights and Measures, Mensura- tion of Superfices and Solids, Tables of Squares and Cubes, Square and Cube Roots, Circumference and Areas of Cir- cles, the Mechanical Powers, Centres of Gravity, Gravita- tion of Bodies, Pendulums, Specific Gravity of Bodies, Strength, Weight, and Crush of Materials, Water-Wheels, Hydrostatics, Hydraulics, Statics, Centres of Percussion and Gyration, Friction Heat, Tables of the Weight of Metals, Scantling, etc., Steam and the Steam-Engine. Nineteenth edition, revised, i6mo, full morocco 1 50 Engineers', Contractors', and Surveyors' Pocket Table- Book. Comprising Logarithms of Numbers, Logarithmic Sines and Tangents, Natural Sines and Natural Tangents, the Traverse Table, and a full and complete set of Excava- tion and Embankment Tables, together with numerous other valuable tables for Engineers, etc. Eleventh edition, revised, i6mo, full morocco I 50 SHELLEN (Dr. H.) Dynamo-Electric Machines. Translated, with much new matter on American practice, and many il- lustrations which now appear for the first time in print. 8vo, cloth, New York (In press) SHOCK (Chief-Eng. W. H.) Steam-Boilers : their Design, Construction, and Management. 450 pages text. Illustrated with 150 wood-cuts and 36 full-page plates (several double). Quarto. Illustrated. Half morocco 15 00 SHUNK (W. F.) The Field Engineer. A handy book of prac- tice in the Survey, Location, and Track-work of Railroads, containing a large collection of Rules and Tables, original and selected, applicable to both the Standard and Narrow Gauge, and prepared with special reference to the wants of the young Engineer. Third edition. i2mo, morocco, tucks 2 50 SHIELDS (J. E.) Notes on Engineering Construction. Em- bracing Discussions of the Principles involved, and Descrip- tions of the Material employed in Tunnelling, Bridging, Canal and Road Building, etc., etc. i2mo, cloth 1 50 SHREVE (S. H ) A Treatise on the Strength of Bridges and Roofs. Comprising the determination of Algebraic formu- las for strains in Horizontal, Inclined or Rafter, Triangular, Bowstring, Lenticular, and other Trusses, from fixed and moving loads, with pr ctical applications and examples, for the use of Students and Engineers. 87 wood-cut illustra- tions. Third edition. 8vo, cloth 3 50 r a s O +^ C _ ,d k n •g 1£ £ a g 5 © ° £ O r! *i 03 ^ O O u m w ~ +3 03 &o ,3 'S 8-8 d- ft~s 2 *s 03 p- ^r-H- 03 5h c3 ' o co J-i o © ©O G $1*1 *2 '. o $ ns c*o © 03 d © recesses ?e - M. of .C.CI on By he 3n- >n. pte >m- :m- of rA3 lil-N O-Xl^l lii . By ANITARY PLUMB- i . du Moncel. FOUR PLACES OF ^ERY. By Silvanus J. Flynn. : Briggs. Prof. Foye. r M. P. E. Berthelot. rice. 1 27 Warrea Sts., I Y. THE UNIVERSITY SERIE L — ON THE PHYSICAL BASIS OF LIFE. Prof. T. K. Huxley, LL.D. F.R.S. With an introd v c tion by a Professor in Yale 'Jollejre. 12mo, pp. - Paper Covers. Price 25 o.^t&. II. — THE CORRELATION OF VITAL Ax; PH STSIJAL FORCES. B7 Prof. George F. Bark * M.D., of Yale College. 36 pp. a/aper Covers. Price 2; III. r~AS REGARDS PROTOPLASM, in relate to Prof. Huxley's Physical Basis of Life. By Hu pchison Stirling, F.R.C.S. pp. 72. Price 25 cei^t IV. — ON THE HYPOTHESIS OF EVOLUTIC Physical and Metaphysical. By Prof Edward J Cope, 12mo., 72 pp. Paper Covers. Price 25 cenxr V. — SCIENTIFIC ADDRESSES : — 1. On the Me thods and Tenderizes of Physical Investigation. 2. Or. Haze and Dust 3. On the Scientific Use of the Imart- nation. By Prof. John Tyndall, F.R.S. 12mo, pp. Pap^r Covers. Price 25 cents. Flex. Cloth. 50 c NO. V^.-NATURALSEIEC^: ~ 4* APPLIi TO MAN. By Alfred Pl^s. t u V'llace. T3 pamphlet treats (1) of the Ite 1 iopment of Hun Races under the law of selection , ^2) the limits of N> ural Selection as applied to man . 5 1 pp. Price 25 cen s NO. VII.- SPECTRUM ANALYSIS. Three k tures by Profs. Roscoe, Huggins, and Lockyer. Fin< ly illustrated. 88 pp. Paper Covers. Price 25 cent? " NO. VIH.— THE SUN. A sketch of the preset statu of scientific opinion as regards this body, with a account of the most recent discoveries and methods < observation. By Prof. C. A. Young, Ph.D., of Dai ! moutr College. 58 pp. Paper Covers. Price 25 cent NO. IX.— THE EARTH A GPEAT MAGNET. P A. M. Mayer, Ph.D., of Stev^jp Institute. A mc profourdly interesting lecture on *he subject of rn& : : netism. 72 pp. Paper Covers. Prio 25 cents. Fles ible Cloth, 50 cents. NO. X. — MYSTERIES OF THE VOICE ANI FAR. By Prof. O. N. Rood, Columbia College, Ne York. One of the most interesting lectures on soun>^ ever delivered. Original discoveries, brilliant exper' ments. Beautifully illus. 38 pp. Paper Covers 25 etc