V REESE LIBRARY OF THK UNIVERSITY OF CALIFORNIA. Received Accessions ^.^ 32. ANTIMONY ALLOYS. Name. Copper. Tin. 10 24 100 90 Lead. Antimony. Bismuth. *i Babbitt's metal . . Do Expanding alloy . . Pewter Type metal White brass .. .. Do 1 1 'i 3 3 to 7 7 1 2 2 17 1 7 7 NOTES IN MECHANICAL ENGINEEKING. 33. VARIOUS ALLOYS. 15 Name. Copper. Tin. Zinc. Various. Pot or cock metal . . 5 2 lead. Cowper's metal . . 2 1 bismuth. Aluminium bronze 90 1 1 10 aluminium. Sterro-metal 60 2 35 3 wrought iron. Gedge's metal 60 38-2 1'8 34. MELTING POINTS OF VARIOUS METALS. Wrought iron .. .. .. 3250 Fahr. Steel 3250 Cast iron 2750 Copper 2000 Gun-metal 1900 Yellow brass 1850 Aluminium 1800 Antimony 810 Zinc 770 Lead 620 Bismuth 500 Tin .. ... 440 35. WEIGHT OF VARIOUS METALS IN POUNDS. Name. Cubic inch. Cubic foot. Gold , 70 1203 Lead .. .. 41 710 Copper 32 555 Gun-metal . . 31 530 Brass . . 30 525 Muntz metal 29 510 Steel .. .. 28 490 Wrought iron 28 480 Tin . . 26 460 Cast iron 26 450 Zinc . . 25 435 Aluminium 09 160 16 NOTES IN MECHANICAL ENGINEERING. 36. USE OF WOOD IN ENGINEERING. Pattern-making. American yellow pine, Kew Zealand pine, mahogany, alder, sycamore. Searings. Lignum vitaB. Brake BlocJcs. Willow, poplar. Buffer Beams. Oak. Floats for Paddle-wheels. Willow, American elm, English elm. Wheel Teeth. Hornbeam, beech, holly, apple, oak if in damp place. Sluice Paddles. Oak, greenheart. Joiners' Tools. Beech, box. Shafts and Springs. Ash, hickory, lancewood. Ordinary framing, piling, &c. Yellow deal. Carriage-building. Teak. Fender and Hubbing pieces. American elm. 37. FIR, DEAL, AND PINE. Fir is a general term for wood used in the rough, as distinguished from Deal, a general term for wood wrought and used by the joiner. Pine is another general term used for even grained stuff suitable for panels. Also for pitch pine. Yellow deal and red deal are botanically classed as pine. White deal and spruce deal are botanically classed as fir. Deal is not a botanical term. Planks, deals, and battens, are trade terms for boards of certain widths, viz., planks 11 inches, deals 9 inches, battens 4 to 7 inches. KOTES IN MECHANICAL ENGINEERING. 17 PART I. SECTION III. THE BEHAVIOUR OF MATERIALS UNDER STRAIN THE STRENGTH OF BEAMS, SHAFTS, BRACKETS, ETC. 38. CLASSIFICATION OP STKAINS. Tension Stretching or pulling. Compression .. .. .. Crushing or pushing. Transverse Strain .. .. Cross strain or bending. Torsion Twisting or wrenching. Shearing . . j Cuttin g> > or when actin S alon g 1 the grain of timber, detrusion. 39. DEFINITIONS OF STRAIN AND STRESS. Strain. Every load which acts on a structure produces a change of form, which is termed the strain due to the load. The strain may be temporary or permanent, the former dis- appearing when the load is removed, the latter remaining as permanent set. Stress. The molecular forces, or forces acting within the material of a structure, which are called into play by external forces, and which resist its deformation, are termed stresses. Univin's Machine Design. 40. TESTING WROUGHT IRON.* The strength of a bar should be measured by the work done in producing rupture, i.e. the product of the elongation into the mean stress. A convenient approximation to relative toughness is obtained by observing the maximum stress and the elongation in a given length. The length formerly taken was 8 inches, but 6 inches is now usually adopted, so that the increase of length in sixteenths of an inch will * Sec leaflet by the author on ' The Behaviour of Materials under Strain.' 18 NOTES IN MECHANICAL ENGINEERING:. represent the elongation per cent. The elongation being principally local, the percentage specified for a length of 8 inches x -f^)- or 1*28, will give the proper percentage for a length of 6 inches. 41. FACTOR OP SAFETY Is an amount fixed by practical experience, varying with the material used, and the manner of using. It is the ratio of the greatest safe stress to the ultimate resistance of the material, such as J, y 1 ^, &c., and the calculated resistance of any section multiplied by the factor of safety suitable to the circumstances, will give the safe working load. 42. PROOF STRENGTH. It was formerly supposed that the proof strength of any material was the utmost strength consistent with perfect elasticity '; that is, the utmost stress which does not produce a permanent set. Mr. Hodgkinson, however, has proved that a set is produced in many cases by a stress perfectly consist- ent with safety. The determination of proof strength by ex- periment is now, therefore, a matter of some obscurity ; but it may be considered that the best test known is, the not producing an increasing set by repeated application. Ranldne's Applied Mechanics. 43. MOMENTS OF TRANSVERSE STRENGTH. Moment of Load is the load multiplied by its effective leverage at the point required. The moment of a load divided by the depth of beam will give the horizontal strain on the extreme fibres in its upper and lower sides. Moment of Resistance in a beam is proportional to the area of the fibres multiplied by the squares of their distances from the neutral axis. Moment of Inertia is the sum of the moments of resistance in any given section. Hurst. NOTES IN MECHANICAL ENGINEERING. 19 44. USUAL ALLOWANCE FOR DEAD LOAD PER SQUARE INCH SECTIONAL AREA. Breaking Strain. Safe Load. WROUGHT IRON Tension 22 tons 5 tons. Compression 18 ., 4 CAST IRON Tension 7 If* Compression t 42 7 STEEL Tension 35 8 Compression 50 12 45. SAFE LOAD ON STRUCTURES. Cast-iron columns . . "j Cast-iron girders for tanks = breaking weight Wrought-iron structures Cast-iron for bridges and floors = -J Stone and bricks = -- Timber = T V Moleswortli. 46. SAFE LOAD ON FLOORS. Churches and public buildings, 1J cwt. per square foot Warehouses 2J Dwelling houses 1J ,, 47. WEIGHT OF MEN IN CROWDS. Mr. Cowper found by experiment that a number of men averaged 140 Ibs. per square foot. Mr. Parsey considers that men packed closely would weigh at least 112 Ibs. per square foot, but that in ordinary crowds 80 Ibs. might be taken as sufficient. On the continent it is not usual to estimate so high. o 2 20 NOTES IN MECHANICAL ENGINEERING. Belgians weigh about 140 Ibs. each, Frenchmen 136 Ibs., while Englishmen weigh 150 Ibs. Mr. F. Young states 80 Ibs. per square foot is quite safe in practice. Mr. Thomas Page packed picked men on a weighbridge with a result of 84 Ibs. per foot super. Mr. George Gordon Page says that for troops on march 351 Ibs. per square foot is sufficient. The usual practice is to assume the live load as 100 Ibs. per square foot. A. T. Walmisley. 48. APPROXIMATE SAFE LOAD ON COLUMNS AND PIERS Oak post up to 10 diameters long, T 3 ^- tons per sq. in. Fir ^ Cast-iron column ) - or stanchion $ Do. 10 to 15 4 ., Do. 15 to 20 3 Do. 20 to 25 2 Do. 25 to 30 H Hard York or Portland stone piers 12 foot super. Stock brick in cement (if covered with) stone template) j (without do.).. 4 49. WEIGHT OF MATERIALS FOR ESTIMATING. Wrought iron .. .. 480 Ibs. per cub. ft. Cast iron .. .. .. 450 Gun metal .. .. .. 525 Lead 700 Greenheart .. .. .. 60 ., Oak 50 Fir 40 Granite .. .. .. ICO ,, Bramley Fall and Hard York 140 NOTES IN MECHANICAL ENGINEERING. 21 50. SPECIFICATION TESTS OF CAST IRON. (BRIDGE AND GIRDER WORK.) Three bars cast in dry mould from each melting, 3 feet 6 inches long, 2 inches deep, 1 inch wide ; 3 feet between bear- ings, to break with average of 30 cwt. in centre, or minimum of 28 cwt., and to deflect not less than T V with load of 25 cwt. Samples prepared in lathe to bear 2 tons per square inch tensile strain before loss of elasticity, and to break with not less than 7 tons per square inch. 51. SPECIFICATION TESTS OF WROUGHT IRON (BRIDGE A GIRDER WORK). Tons Elongation* Contraction Class. per square inch, per cent, at per cent, at Tensile Strength. Twenty Tons. Point of Fracture. Rivet iron 25 10 30 Rod and bar iron 24 71 20 Angle and tee iron 22 6 15 Plates, with grain 21 41 10 Plates, across grain 18 5 * In a length of 8 inches. 52. SPECIFICATION TESTS OF WROUGHT IRON (SHIPBUILDING). Class. Tons per square inch, Tensile Strength. Elongation* per cent, on Fracture. Toughness.! Rivet iron 26 25 6f>0 Bod and bar iron 24 15 360 Angle and tee iron . . 22 - 123 275 Plates, with grain 20 7 150 Plates, across grain . . 19 6 1H * In a length of 6i inches. f Should the actual elongation in sixteenths of an inch, multiplied by the stress in tons per square inch, upon rupture, be more than 10 per cent, under the amounts given in the last column, the iron will be rejected. Cold bending in vice ^-inch plate 35, -inch plate 55 5 J-inch plate 63, ^-inch plate 70, rivet iron to double close, without cracking. 22 NOTES IN MECHANICAL ENGINEERING-. 53. DESIGNING WROUGHT IRONWARE. Limits of ordinary prices, Staffordshire district. Plates. Weight 5 cwt., length 15 feet, width 4 feet, 30 feet super, shape regular. Angle and Tee Irons. Length 40 feet, size 2J inches by 2 IT by 1J- up to 8 united inches. Bars. (Round and square), diameter -J- inch to 3 inches, length 25 feet. Bars. (Flat), size 1 inch by J inch up to 6 inches by 1 inch, length 25 feet. CLEVELAND DISTRICT. Plates. Weight 12 cwt., length 21 feet, width 4 feet G inches, shape regular. 53*. COMPARATIVE STRENGTH OP IRON AND STEEL PLATES. Quality. Ultimate Tensile Strength. Elongation per cent. With Grain. [Across Grain. With Grain. Across Grain. Mild steel .. .. Best Yorkshire B. B. Staffordshire B. 80 24 22 20 28 22 19 18 20 12 9 6 18 5 2 54. ULTIMATE STRENGTH OF VARIOUS METALS AND ALLOYS. Name. Tension. Tons per sq. in. Compression. Tons per sq. in. Aluminium bronze 25 Phosphor bronze Muntz metal 25 20 Malleable cast iron 15 45 Copper (sheet and bolt) 15 Copper (cast) 10 . . Gun metal 12 48 Brass 10 5 Cast lead 6 3 Zinc.. .. .. .. 3 Tin .... .... 2 NOTES IN MECHANICAL ENGINEERING. 23 55. LIMIT OF ELASTICITY. The maximum strain per square inch sectional area, which any material can undergo without receiving a visible perma- nent set, is called its limit of elasticity. The average limits of elasticity are Wrought iron, 10 tons. Cast iron, 2 tons. Steel, 15 tons. And the average elongations under a strain of 1 ton per square inch are Wrought iron 3-^}^. Cast iron y^r- Steel 56. MODULUS OF ELASTICITY. A bar in tension or compression is elongated or shortened by an amount proportionate to the strain, within certain limits. Assuming the elongation, on increasing the strain, to continue in the same ratio, a certain point would be reached where the bar would be increased to twice its original length. The weight in Ibs. per square inch sectional area of the bar, to produce this result, is the modulus of elasticity. The amount varies with the kind and quality of the material employed. 57. DEFINITIONS OF MODULUS OF ELASTICITY. The modulus of direct elasticity of a material is the ratio of the stress per unit of section of a bar, to the elongation or compression per unit of length, produced by the stress. Unwin's Machine Design. It is the weight in Ibs. that would stretch or compress a bar, having a sectional area of one square inch, by an amount equal to its own length, called Hooke's law. CargiWs Strains. 58. FORMULA FOR ELONGATION BY ELASTICITY. M = Modulus of direct elasticity (see table). I = Length in inches. 24 NOTES IN MECHANICAL ENGINEERING w = Load per square inch sectional area, in Ibs. e = Elongation in inches. w X I 59. MODULI OF ELASTICITY. In Ibs. per sq. in. Cast steel, tempered ........ 36,000,000 Steel, ordinary ....... , .. 30,000,000 Wrought-iron bar ........ 29,000,000 Ditto plate ............ 25,000,000 Cast iron ............ 18,000,000 Copper ............ 17,000,COO Phosphor bronze ........ 14,000,000 Gun metal ............ 10,000,000 Brass ............... 9,000,000 Tin .............. 5,000,000 Lead .............. 720,000 CO. ALLOWANCE IN BRIDGES FOE CHANGES OF TEMPERATURE. Variation of 15 F. alters length of wrought iron as much as strain of 1 ton per square inch. In exposed situations an allowance of T 7 ^ of an inch move- ment, per 100 feet length, is necessary for the purpose of eliminating the strains due to change of temperature. Graham Smith. 61. RESILIENCE OF BEAMS. The resistance of beams to transverse impact, or a sud- denly applied load, is termed their resilience. It is simply proportional to the mass or weight of the beam, irrespec- tive of the length or the proportion between the depth and breadth. Thus, if a given beam break with a certain steady load, a similar beam of twice the length will break with half the NOTES IN MECHANICAL ENGINEERING. 25 load applied in the same way; but if the short beam be deflected or broken by a certain falling load, the long beam will require double the load dropped from the same height or the load dropped from twice the height, to produce the same effect. Anderson's Strength of Materials. 62. RESILIENCE. Resilience or Spring is the quantity of mechanical work required to produce the proof- stress on a given piece of material, and is equal to the product of the proof strain or alteration of figure, into the mean load which acts during the production of that strain ; that is to say, in general, very nearly one half of the proof load. The Resilience or Spring of a Beam is the work performed in bending it to the proof deflection : in other words, the energy of the greatest shock which the beam can bear with- out injury : such energy being expressed by the product of a weight into the height from which it must fall to produce the shock in question. This, if the load be concentrated at or near one point, is the product of half the proof load into the proof deflection. Rankine* 63. ULTIMATE STRENGTH OP TIMBER. Name. Tension. per square inch. Compression, per square inch. Ash 7Jto 5 6 5 5 5 H 6 5i 5i , 7 , 4J , ns ? > 4 tons. 4 4 2j" 2| 1*,, ar 4 8i 3 5 Beech Elm .. .. Eiga fir . . Memel fiir Larch Honduras mah( English oak Dantzic Canada Teak.. .. Pitch pine )gany .. . 26 NOTES IN MECHANICAL ENGINEERING. 64. STRENGTH AND STIFFNESS OF TIMBER. Name. Stiffness. Strength. Resilience. Ash 89 119 ICO Beech Kigafir Memel fir ... Larch .. .. . Honduras raahogan English oak . . Dantzic v 77 98 114 79 93 100 117 103 80 80 103 96 100 107 138 64 56 134 99 100 99 Canada Teak Pitch pine 114 126 73 86 109 82 64 94 92 Oak being taken for comparison as = 100. 65. PROPORTIONS OF BEAMS FOR STRENGTH AND STIFFNESS. Strongest Stiffest d : I : : V2 : 1 d : b : : J3 : 1 Approximately for strength, d to b as 1 to 7 ; and for stiff- ness as 1 to * 58 ; but 1 to 5 is often used for beams, where the ends can be fixed sideways, because two can be cut out of a square log, and 1 to 33 or three out of a square log when intermediate staying can be applied, as in joists. 66. APPROXIMATE PROPORTIONS OF BEAMS. Strength. Stiffness. Convenience. inches. inches. inches. 12 x 8J 12 x 7 12 x 9 or 12 x 6 10 x 7 10 x 6 10 x 5 9 x 6 8x5* 9x5| 8x4| 9x6 or 9 x 4|j 8x6 or 8 x 4 7x 5 7x4 7 X 4 or 7 x 2 6 X 4J 6 x 3i 6x4 5 X 3i 5x3 5x3 4x3" 4 x 2i 4x3 or 4 x 2 3x2 3 X 1 3x2 NOTES IN MECHANICAL ENGINEERING. 27 67. DEFLECTION AND CAMBER. Deflection is the displacement of any point in a loaded beam, from its position when the beam is unloaded. Camber is an upward curvature, similar and equal to the maximum calculated deflection, given to a beam or girder or some line in it, in order to ensure its horizontality when fully loaded. 68. DEFLECTION OF GIRDERS. In girders with parallel flanges of uniform strength, the deflection produces a circular curve, the amount of deflection varies directly as the load x the sum of the areas of both flanges X the cube of the length, and inversely as the area of top flange X area of bottom flange X depth of web squared, or A= WjjCg ? +a>)xP t X a b X d 2 Common Rule. Girders to be constructed with a camber of J to J inch per 10 feet of span, to allow for deflection when loaded. 69. FORMULA FOR DEFLECTION OF WROUGHT-IRON FLANGED GIRDERS. Of uniform strength, supported at both ends, and carrying distributed load. Strain allowed = 5 tons per square inch tension, 4 tons per square inch compression. s = Span in feet. d = Mean depth in inches. A = Deflection in inches in centre. 0144s 2 A = d If depth = T V span, A = -012 s, T V = '0144 s, X = 0.18s. 28 NOTES IN MECHANICAL ENGINEERING. 70. DEFLECTION or BEAMS. . A = Deflection in inches. I = Length in feet. 6 = Breadth in inches. d Depth in inches. W = Load in cwts. in centre, c = Constant = .. 40 .. 36 .. 30 .. 26 Rectangular beam Z 3 W Steel .. .. .. 700 Quebec oak Wrought iron .. 500 Fir and deal Cast iron .. 350 Dantzic oak Teak .. .. .. 50 Pitch pine Z 3 W , // 3 W _ , 3 b = d = A/ T- b d 3 = V AC 4 // 3 W = \/ - Square beam, side /PW Cylindrical beam, diameter = A/ X 1 ' 7. If load be uniformly distributed, deflection = -f A. Cantilever with distributed load = A 6. Cantilever loaded at end = A 16. Safe deflection in timber = | 7 length, or ^ inch per foot span. 71. NOTES ON TORSION AND SHAFTING. Torsion is measured by the load acting at 1 foot radius, which is required to fracture a specimen 1 inch diameter. Torsion is similar to shearing, and could be calculated as NOTES IN MECHANICAL ENGINEERING. 29 such, but it is more convenient to take it by leverage as above. d 3 d* Strength varies as , stiffness as To run smoothly, long shafting must not twist more than 1 in 10 feet under maximum load. Long shafts are not designed in strict accordance with rule as they would then be tapered from driving end, involving extra assortment of driving pulleys. Every alteration in diameter of a shaft, unless made at a coupling, must be made gradually by means of a curve at the junction of the two diameters. Factor of safety, long shafts less than 4J inches diameter = T \j-; short shafts and all over 4J inches diameter = ^. Distance apart of supports in feet = 5 tyd 2 . Friction of ordinary shop shafting is about one horse-power per 100 feet. 72. ULTIMATE TORSIONAL STRENGTH OF VARIOUS METALS. Round bars 1 inch diameter, load applied at 1 foot radius. Cast steel, average 1500 Ibs. Mild steel, 1200 Wrought iron, 800 Cast iron, 700 Wrought copper, 400 73. TRANSMISSION OF POWER BY SHAFTING. Strength of shaft to transmit power depends upon velocity : thus, shaft able to transmit 20 horse-power at 60 revolutions is sufficient for 60 horse-power at 180 revolutions. The ex- planation is, that the actual strain is the same in each case the increase in horse-power being due to the increase in speed only. Power consists of pressure and velocity, and varies directly as the amount of each. 30 NOTES IN MECHANICAL ENGINEEKING. 74. FORMULA FOR STRENGTH OF SHAFTING. W = B. W. in Ibs. at 1 foot radius, of shaft 1 inch diameter. C = Coefficient of safety. d - Diameter of shaft. Z = Leverage in feet. s = Strain in Ibs. at circumference of wheel. 3 / Sl ~~ V w^ Wd 2 X c. 75. MOLESWORTH'S FORMULA FOR WROUGHT-IRON SHAFTING. D = Diameter of shaft in inches. 1320 for crank shafts and prime movers. 200 for second motion shafts. 100 for ordinary shafting. H = Actual horse-power to be transmitted, n = Number of revolutions per minute. Z = Leverage in feet. / = Force applied in Ibs. at circumference of wheel. H = v H = 33000 ' K 33000H 3/H X^^vK y 27rZra ~ V n* ~V 33000 Xi 76. PROPORTIONS OF SOLID WROUGHT-IRON FLANGE COUPLING ON SCREW SHAFT. Let d = diameter of shaft. Then there should be eight bolts,* each J d in diameter, the diameter of circle passing through the centres being 1 d. The flanges should be 2 d in diameter and d thick. Unwin. * Six bolts are commonly used, np to 6 inches diameter of shaft. NOTES IN MECHANICAL ENGINEERING. 31 77. TRANSVERSE STRENGTH OF SHAFTS. Load distributed on wrought-iron crank pin or over- hanging journal in Ibs., c = 1200. Ditto, concentrated on shaft supported at ends, c = 2400. Ditto, distributed c = 4800. Safe load = c d = WZ 3/ _ - V c ' Forces may be taken to act at the centres of journals in cases where supports are not contiguous to journals. 78. PROPORTIONS OF BOLTS, WHITWORTH STANDARD. Diameter of Bolt in inches. Width of Nut over Angles, approx. = If diam. Width of Nut over Sides. approx. = li diam. Diameter at top of Chamfering. Thickness of Head. No. of Threads per inch. * A 1 1? f || 7 12 11 I ^ . If *rV 1 T6 I 10 1* P i! If H 9 8 H Is 2i I 8 7 If K"** 2-^ 2* 2 10 H 6 2 & 3J 3 2| if 4J 3 * 5i 4i 4 3i Thickness of nut = diameter of bolt. Depth of thread = pitch. Number square threads = number V threads. 79. PROPORTIONS OF BOLTS, NUTS, AND WASHERS IN CARPENTRY. Thickness of nut head = Diameter of head or nut over sides = Side of square washer for fir .. = = 1 diameter of bolt 32 NOTES IN MECHANICAL ENGINEERING. Side of square washer for oak . . = 2^ diameter of bolt. Thickness of washer = ^ ' When the nuts are let in flush in fir, the washers should be same size as for oak. 80. STRENGTH OP BOLTS. Bolts in machinery subject to varying loads should not be strained to more than 2 tons per square inch of minimum section. A bolt 1 inch diameter being *84 at bottom of thread will take not more than (say) 2000 Ibs., including initial strain in screwing up. Let d = outside diameter of thread in inches ; 2000 d 2 = safe load in Ibs. for 1-inch bolts and upwards; 2000 d 3 = safe load in Ibs. for 1-inch bolts and under. The ordinary force used in screwing up bolts is liable to break a f -inch bolt and seriously injure a |^-inch bolt ; hence bolts, for joints requiring to be tightly screwed up should not be less than f inch in diameter. 81. STRENGTH OF BOLTS (Unwin). Bolts not requiring to be tightened before load is ap- Per sq. in. net area. Safe load = 6000 Ibs. plied Bolts accurately fitted "j and requiring to be tight- > = 4000 ened moderately . . . . j Bolts used to draw joints } steam tight and resist the I = 1600 to 2000 Ibs. pressure in addition . . J 82. To SECURE CHECK OB LOCK NUTS. Put on check nut (^ diameter of bolt in thickness), screw up as tight against flange or work as an ordinary nut would be screwed under the circumstances, then put on ordinary NOTES IN MECHANICAL ENGINEERING. 33 thick nut (1 diameter thick), screw it up with the same force and hold on to it with the spanner. Then with a thin spanner reverse the check nut against the other as far as it will go with about the same pressure as before. The check nut has then only the screwing-up force to resist, while the thick nut has in addition the strain which may be brought upon it by load or vibration. 83. CHECK NUTS. .... This loosening of a nut can be prevented by adding another nut, which must be screwed hard down upon the first, to increase the pressure upon the thread. WiUis 9 Mechanism. NOTE. As described here, the second nut would only be equivalent to thickening the first nut, and would be useless as a check. PAET I. SECTION IV. THE ACTION OF CHISELS, HAMMERS, PUNCHED" PLANES, SHEARS, DRILLS. 84. FORMULA FOR FALLING BODIES. h = Height of fall in feet. H = Highest point reached in feet. v = Velocity in feet per second. T = Time to reach ditto. g = Force of gravity .= 32 (ap- V = Velocity imparted otherwise proximately). than by gravity. t Time of fall in seconds. Falling from Rest. Thrown Downward. 27i h = V t + - V + */2g~h = V + g t 9* 34 NOTES IN MECHANICAL ENGINEERING. Thrown Upward. V2 V 2 ' .T>if..g t> = V- 85. HOLTZAPFFEL'S CLASSIFICATION OF CUTTING TOOLS. Shearing tools act by dividing the material operated on into two parts, which separate from each other by sliding at the surface of separation. Paring tools cut a thin layer or strip called a shaving from the surface of the work, and thus produce a new surface. Scraping tools scrape away small particles from the surface of the work, thus correcting the small irregularities which may have been left by the paring tool. 86. ANGLES OF TOOLS. Angle of Tool. Speed of Cut. For wood 30-40 8000 feet per minute. wrought iron 60 15-20 cast iron .. 70 10-15 brass .. ..80 Angle of relief for all tools, 5-10. 87. CUTTING SPEED OF MACHINE TOOLS. Steel .. .. 12 feet per minute Cast iron .. 18 Brass .... 20 Wrought iron 24 Wood .. .. 2000 when material revolves. NOTES IN MECHANICAL ENGINEERING. 35 Wood .. .. 3000 feet per minute when tool revolves. Grindstone .. 800 feet per minute. 88. SPEED OP MACHINE TOOLS. On soft cast iron .. 5 feet per minute. steel and hard ditto 10 to 20 wrought iron .. 15 to 25 brass 40 to 100 wood 300 to 2000 Evers' Applied Mechanics. 89. SPEED OF MACHINE TOOLS. (Wrought iron, 20 feet per minute. Cast iron, 16 Cuts per inch, 16 to 80. Tor flat work- Speed in inches per second x 5 = speed in feet per minute. For small diameters Diameter in inches x revolutions in 16 seconds = Epeed in feet per minute. For large diameters Diar. in inches X 16 Seconds for 1 revolution = S ^ eed in ft ^ min * Cutting speed in feet per min. x 5 Cuts per inch ~ = S 1' ft ' tooled P er hour - Engineering, 21st Nov. 1879. 90. SHEARING AND PUNCHING. Resistance to shearing of wrought iron averages 50,000 Ibs. per square inch area of surface cut. This will be the pres- sure required on the material at the commencement of the stroke. D 2 36 NOTES IN MECHANICAL ENGINEERING. The mechanical work in punching or shearing is estimated by Weisbach as this pressure exerted through ^th the thick- ness of the plate, and the coefficient or modulus of the machine as 66, the friction being taken at 33 per cent, of the gross pressure. 91. SHEARING AND PUNCHING. Formula for calculating power required : t = Thickness of plate or bar. I = Length or circumference of cut. / = Resistance of material to shearing. M = Modulus of machine, say *66. P = Gross pressure in Ibs. P-il/ " M 92. PRESSURE REQUIRED TO PUNCH WROUGHT-IRON PLATES. (From experiments). d. t. P. c. To punch i- hole in -J- plate requires 2| tons = 144 Do. i j 64 104 Do. t 13 92 Do. i J 22 88 Do. -| f 33J 86 Do. J f 47i 84 Do. |- 62J 82 Do. 1 1 80 80 P = d X t X c. Approximately diam. X thickness x 88 = pressure in tons , or, area of cut surface x 28 = ditto 93. LAWS OF FBICTION. The friction between two surfaces, dry or only slightly greasy, is in direct proportion to the force with which they are pressed together (within the limits of abrasion), and is NOTES IN MECHANICAL ENGINEERING-. 37 independent of the area of the surfaces in contact. With ample lubrication the friction is reduced, but the heavier the pressure per unit of surface the greater must be the consist- ency of the lubricant, to prevent it from being squeezed out. The friction between two surfaces at rest is slightly greater than when they are in motion, but when in motion the friction is independent of the velocity so long as the surfaces are kept cool. 94. DEFINITIONS OF FRICTION. The Limiting angle of Resistance is the angle through which any surface requires to be lifted from the horizontal to cause a body to be on the point of sliding (friction of rest) or to continue sliding (friction of motion). Its magnitude is fixed by the physical nature of the surfaces in contact. It is also the angle from the vertical made by the resultant of the force or forces acting upon a body when sliding is just about to take place or is taking place. The Coefficient of Friction /x is the ratio of the pressure P required to overcome the friction of a body on any given horizontal surface, to the whole load W of and on the body (p, = ~r Y Trigonometrically it is equal to the tangent of the limiting angle of resistance (/x = tangent $). 95. MEAN COEFFICIENTS OF FRICTION. Wood on wood or metal dry, 4 to 6 ; greasy, 2 to * 4 ; lubricated, 1 to '2. Metal on metal wet, 3 ; dry, 2 ; greasy, 15 ; lubricated, 1 standing, or 08 moving. Leather on metal, wet '25, dry *5. Friction of motion = friction of repose X * 7. Frictioa varies with the nature of the surfaces, the lubri- cant, and the temperature. 38 NOTES IN MECHANICAL ENGINEERING. 96. MORIN'S EXPERIMENTS ON FRICTION, OF MOTION. Dry Wrought iron on brass *172 Brass on wrought iron 161 Cast -147 cast -217 Greasy Wrought -160 wrought -166 Cast -132 cast -107 Lubricated with olive oil Wrought -078 wrought -072 Cast -078 cast -077 Oak upon elm dry = ^ of friction of elm upon oak dry. NOTE. These results reduced from General Morin's experi- ments appear to be very questionable, and indicate the neces- sity for further investigation. PAET I. SECTION V. OPERATIONS OF TEMPERING, WELDING, RIVETING, CAULKING, &c. 97. FORGING. Wrought iron at a red heat may be hammered into various shapes, called "forging." When a piece is drawn down smaller it is called " swaging ; " if jumped up thicker, it is called " upsetting." Common iron is not suitable for forging, as the scale or slag in it causes cracks. Double and treble best Staffordshire and ordinary Yorkshire are suitable. The best Yorkshire is used for flanging and difficult forgings. Charcoal iron for light and complicated work. Steel may be forged gradually at a low heat. The greater NOTES IN MECHANICAL ENGINEERING. 39 the proportion of carbon contained, the greater the difficulty of forging. All forging should proceed by easy stages, and care be taken not to burn the iron or steel. 98. WELDING Is the process of joining two pieces of wrought iron or steel by heating, and hammering them together. To weld iron the pieces must be 'brought to a white heat, and the scale swept off before they are put together. Steel requires a much lower heat, and the surfaces should be sprinkled with sand or borax. The welding temperature depends upon the amount of carbon contained: hence, the extra difficulty of welding two pieces of /different composition. Mild steel approaches wrought iron in its welding qualities. Steel faces may with care be welded on to iron tools; shear steel is generally used for this purpose. 99. TEMPERING. Steel when heated to a cherry red, and suddenly cooled in water or oil, is rendered very hard. Some suppose that the carbon is caused to take the crystalline or diamond form. For tempering the hardened steel a portion is brightened with a piece of broken grindstone, and then reheated until the film of oxide formed on the surface shows the requisite temperature; it is then quenched in water, and the hard- ness is found to be " let down " to the " temper " required. Tempering was formerly considered to be the only true test of steel. 100. COLOUES CORRESPONDING TO TEMPERATURE. Faint red .. Dull red .. .. Brilliant red Cherry red Bright cherry red Deg. Fahr. .. "960 .. 1290 .. 1470 .. 1650 .. 1830 Deg. Fahr. Orange 2010 Bright orange .. ..2190 White heat 2370 Bright white heat.. .. 2550 Becquerel. 40 NOTES IN MECHANICAL ENGINEERING. fed H H C^ d CO CO CO CO CO CO CO cp. H 1 - 3 - s 1 I : : 3 . c2 ""3 . f . 03 s . , ^ c3 . to a . . . at same. 3 "o : : i 1 : 1 : : : : Llloys fusible ature of Tool. a W 1 crT CH . fE : : a ;i 'o rf .-a 1 to B 1 OS to .S 03 P C3 CQ T3 B 2 rumen ts .. -0 fe C 03 W 1 2 1 & s* 'd OT arious Temperatures, a S 5 1 o g eS Razors and ditto . Penknives . . Cold chisels, drill 6 S3 ei Jf o ^3 ^ f & oa 3 1 1 - m o 1 1 % m [o 1 C3 g of 1 p ^ I etf O 02 8 i | 1 o g S g o CO IO O o . d f rti - tr s * > S s 3 ,s s 'H ^ ^ o ^ ^H : 1 i ^ | c g g ^ 1 fcfl .2 o 3, -^ 8 '^ ^ I | f % ^o 2 r^ ^4 Bismuth = & Tin = i Pattern-makers commonly allow for iron castings -J inch per foot, and for brass castings ^\ inch per foot. 119. BRONZE AND BRASS CASTINGS. Melted in crucibles, wasting prevented by covering surface with mixture of potash, soda and charcoal powder. Copper melted first, then tin, then zinc or antimony, then covering applied. Zinc is best added in form of brass, calculating the copper contained. Large strong castings require the metal exposed to fire in fluid state 8 or 10 hours, proof taken by small ladle and broken when cool, judged by crystallisation, and copper or tin added as required. Before casting, bronze is well stirred with heated iron rods. Brass made by melting together copper scraps, crude zinc or spelter, and charcoal powder, remelted for casting. PAET III. SHAFTING, GEARING, AND GENERAL MACHINERY. 120. TRANSMISSION OP MOTION. By rolling contact, as spur wheels and pinions, crown wheel and pinion, face wheel and lantern, bevil wheels, cones, rack and pinion, &c. By sliding contact, as inclined plane, wedge, cams, swash plate, crown wheel escapement, screw, &c. By wrapping contact, as cords and pulleys, belts and pulleys or riggers, speed pulleys, capstan, fusee of watch, &c. By link work, as levers, cranks, treadle of lathe, &c. Tomkins* Machine Construction. NOTES IN MECHANICAL ENGINEERING. 49 121. USEFUL WORK AND EFFICIENCY. Useful work of a machine is that performed in producing the effect for which the machine is designed. Lost work is that performed in producing other effects. The power of a machine is the energy exerted, and the effect the useful work performed, in some interval of time of definite length. The efficiency of a machine is a fraction expressing the ratio of the useful work to the whole work performed or energy expended. This ratio is also called the modulus or coefficient of the machine. The counter-efficiency is the reciprocal of the efficiency, and is the ratio in which the energy expended is greater than the useful work. Ranhine's Applied Mechanics. 122. VELOCITY EATIO. The velocity ratio in any machine is the proportion between the movement of the power and the movement of the re- sistance, in the same interval of time; for example, in a punching press it may be 100 to 1 = 1 ^-, and in a hydraulic crane 1 to 8 = -J-. These proportions also express the amount of the resistance (including friction), compared with the power or pressure applied. (See definition of virtual velocity.) The term purchase of a machine is applied either to the motion or pressure of the resistance compared with the power; in above examples, the purchase of the punching press would be 100, that of the hydraulic crane 8, but the term is generally restricted to the gaining of pressure by the sacrifice of speed, as in the first case. 123. PRINCIPLE OF VIRTUAL VELOCITIES. If any machine without friction be in equilibrium and the whole be put in motion, the initial pressure P will be to the 50 NOTES IN MECHANICAL ENGINEERING. final pressure p as the final velocity V is to the initial velocity 0, or P : p ; ; V : v, or p V = P v.- In practice, as all machines have friction, p will depend upon the friction, but V will be in accordance with the calculation of the leverage or gearing. Let e = the final pressure by experiment, then p e = friction, and the coefficient or modulus of machine M=- e . 124. DEFINITIONS OP THE PEINCIPLE OF VIRTUAL VELOCITIES. KanJcine's. The effort and resistance are to each other inversely as the velocities, along their lines of action, of the points where they are applied. Twisden's. If a system of pressures, in equilibrium, act on any machine which receives any small displacement, consistent with the connection of the parts of the machine, the algebraical sum of the virtual moments of the pressure will equal zero. 1-25. ANGULAR VELOCITY. The angular velocity of a wheel is the speed of a point in the circumference of an imaginary wheel with unity as radius, and making the same number of revolutions per minute as the given wheel. Velocity is taken in feet per second. Revolutions are taken at per minute. ( Circumferential velocity = -- = "^ = -10472 rn. Angular velocity = 2 _ = = ' 10472 n. NOTES IN MECHANICAL ENGINEERING. 51 126. NOTES ON BELT GEARING (No. 1). Coefficient of friction between ordinary leather belting and cast-iron pulleys or drums = -423. Ultimate strength of ordinary leather belting = 3086 Ibs. per sq. in. vary from -^- inch to \ inch thick, average ^ inch. Breaking Strain. Safe Working Strain. \ ^ Through solid part .. 675 Ibs. .. 225 Ibs. per in. wide Through riveting .. 382 Ibs. .. 127 Through lacing .. .. 210 Ibs. .. 70 - The working strength of the belt must be taken as that of its weakest part, which is, the lacing. The tension of the driving side, which must not exceed the safe working strength of the belt = force transmitted + mean normal tension. The force transmitted = the difference between the ten- si'on of the driving side and the tension of the following side. Welclis Designing Belt Gearing. 127. NOTES ON BELT GEARING (No. 2). When the arc of contact - 180, the force able to be transmitted may be taken as 50 Ibs. per inch wide. If more or less than ^ circumference be embraced by belt, the force transmitted may be increased or reduced by about 2 * 8 Ibs. for very 10 difference from 180. The sum of the tensions, or cross strain on shafting, may be taken as 90 Ibs. per inch wide. The lower side of a belt should be made the driving side when possible, so that the arc of contact may be increased by the sagging of the following side. The actual horse-power capable of being transmitted by a belt = 0015 X velocity in feet per min. X breadth N in inches. To increase. the capability for transmission of power, the diameters of the pulleys may be increased, retaining the same ratio, the increase of power being obtained by the increased velocity alone. E 2 52 NOTES IN MECHANICAL ENGINEERING. 128. NOTES ON BELT GEARING (No. 3). Approximate rule for width of single leather belt, say $, . k . '_ 1100 H.P. inch thick = ^ ; v. ft. per inin. For double belting take T ^-ths of width of an equivalent single belt. Wide belts are less effective per unit of sectional area than narrow belts. Long belts are more effective than short belts. A belt should never exceed 18 inches wide. The velocity of lathe belts should be from 25 to 33 feet per second, = 1500 to 2000 feet per minute. Convexity of pulleys to receive belt = J inch per foot wide. The proportion between the diameters of two pulleys working together should not exceed 6 to 1. Width of pulley = J more than belt. 129. NOTES ON ROPES. Italian hemp ropes are stronger than Eussian hemp. New white ropes are stronger and more pliable than tarred ropes, but the latter retain their strength for a longer period. Tarred ropes are stiffer than white by about ^, and in cold weather somewhat more. Eopes which have been some time in use are more flexible than new ones ; the stiffness of ropes increases after a little rest. ** Wet ropes, if small, are a little more flexible than dry ; if large, a little less flexible. Eopes shorten and swell when wetted. There is considerable loss of strength from strain, and exposure after use, although a rope may appear perfectly sound. Eopes are usually measured by their circumference : hence NOTES IN MECHANICAL ENGINEERING:. 53 a 6-inch rope is one 6 inches in circumference, or about If inch diameter. All ropes should be kept dry and free from lime. 130. STRENGTH OP ROPES. Ultimate strength of new white ropes is about 6000 Ibs. per equare inch sectional area, but good ropes may stand 1000 Ibs. per square inch. Double rope slings are not twice the strength of single rope, owing to inequality of strain ; but in a rope fall with sheaves in good order, each fold of the rope may be counted for the strength. The work absorbed in bending a rope fall over a sheave varies with the size and quality of the rope, the diameter of the rope, the diameter of the sheave, and the tension in the rope. Include weight of running block in calculating load on fall, and both blocks together with the rope, in weight on strop. Snatch block makes practically no difference in lifting power, if it has a good lead. 131. FORMULAE POR STRENGTH OP ROPES. Breaking weight new rope, cwts. = circumference 2 x 5. Safe load on = wt. Ibs. per fath. x 3. B.W. new stretched rope in = (diameter in |ths) 2 . Safe load = wt. Ibs. per fath. x 4. on new rope fall = circumference 2 , good =-- = t > Weight of clean dry rope per) T fathom, in Ibs . . 3 ~ " Minimum diameter of sheave in j _ . , ~ 54 NOTES IN MECHANICAL ENGINEERING. 132. STRENGTH OF CHAINS. d = Diameter of Iron in iths of an Inch. Example f Chain. B.AV. in tons, B.B. short-link crane chain . . = Jd 2 ordinary chain = %d? ordinary chain (Anderson) . . = f d 2 Elswick test in tons, 10 per cent, above Ad-1 _ 33 ^ 2 tons cwts. 18 14 8 13 10 7 8J Admiralty proof strain in tons = -fad* Safe load in tons (Molesworth, p. 215, eleventh! _ ^ 6 15 4 10 Safe load at 5 tons per square inch sectional area = . . in tons, common rule = -fad 2 Maximum temporary load on good annealed! _ 2 ^ 2 chain in cwts . / 4 8| 3 12 3 12 Safe load, ordinary chain (Anderson), in tons . . = -^d 2 ,, for ordinary cranes, in cwts = Ifo 1 at 3 tons per square inch sectional area = coal cranes, in cwts = IJd 2 ,, old chain, quality and condition \ _ 3 7 2 14 2 13 2 5 1 16 Weight in Ibs. per fathom, short-link crane chain = d 2 ordinary = 'SSd 2 3G 133. BEMARKS ON CRANE CHAINS. T^-" B. B. tested short link crane chain (Crown S. C.) should break with a load of 13 tons, if the iron bar from which it is made break with 26 tons per square inch ultimate stress; but a test piece of the chain 4 feet long breaks usually with a load of 9 to 10 tons, generally opening at the welds. Each chain is tested before use with a maxi- mum load of 4J tons, examined link by link and used on Hydraulic Coal Cranes to lift maximum gross load of 1| tons, examined again at frequent intervals and annealed ; any links reduced by wear to J an inch at ends are condemned as worn out ; worn links cut out and remainder used down to same limit. A good chain, properly looked after, will make from 100,000 to 150,000 lifts before it is entirely worn NOTES IN MECHANICAL ENGINEERING. 55 out. These chains occasionally fail in use, although the factor of safety adopted allows so great a margin. 134. WHEEL GEARING, MANCHESTER PITCH. Diametral pitch (Manchester pitch) = No. of teeth Diam. of pitch circle in ins. Circular pitch = ^. .- . , diametral pitch or (tooth + space) in inches. No. of teeth in wheel = diameter x diametral pitch. No. of teeth Diameter of wheel = T - diametral pitch Addition to diameter for increased No. of teeth = No. to be addded diametral pitch " 2 Outside diameter of wheel = diametral pitch diameter pitch circle. 135. NOTES ON TOOTHED GEARING (No. 1). Pinions, wheels, and racks are made of cast iron, cast steel, and malleable cast iron ; the latter is strong, but liable to twist or warp. Pinions are sometimes made of wrought iron ; small gearing is frequently made of gun metal. Gearing is increased in strength by shrouding or flanging up to pitch line. The comparative wear of gearing is inversely proportional to the number of teeth ; hence, pinions wear quicker than wheels. Two teeth on a pinion or wheel is the minimum number in gear at one time. 56 NOTES IN MECHANICAL ENGINEERING. The power capable of being transmitted by gearing depends, within reasonable limits, entirely upon the speed ; the pressure (at pitch line) depends upon the pitch. 136. NOTES ON TOOTHED GEARING (No. 2). The transmission of the power strains the teeth as canti- levers, or s = c, c for cast iron safe load = 600. The working -load should not exceed -^th of the breaking weight. The dimensions of the teeth are proportional to the pitch ; hence, in ordinary proportions the strength is represented by p 2 c, c for cast iron being 1000. The breadth of tooth on face beyond a certain amount, say twice the pitch, cannot be reckoned upon for strength, owing to irregularities in the teeth, and probability of unequal bearing. 137. STRENGTH AND WEIGHT OF TOOTHED GEARING. Safe pressure in Ibs. at pitch line on wheel teeth of average proportions : Cast iron, little shock, = 625 X pitch 2 . moderate shock, = 400 x pitch 2 . excessive shock, = 277 x pitch 2 . The latter case also applies to the iron teeth of mortise wheels, which are made thinner than ordinary teeth of sam pitch. Breadth of teeth = 2 to 2^ times pitch. The weight of toothed gearing in Ibs. approximately, is for spur wheels -38 n I p 2 , Bevil wheels 325 n b p 2 . NOTES IN MECHANICAL ENGINEERING. 57 138. FORMULA FOB STRENGTH OF GEARING. s = strain in Ibs. to be transmitted, calculated at pitch circle. p = pitch in inches. c = constant, when teeth of ordinary proportion = Material. Plain. Shrouded. Cast steel Wrought iron Malleable cast iron Gun metal Cast iron 4000 3000 2000 1500 1000 6000 4500 3000 2000 1500 For slow speeds and uniform pressure, c may be .increased one-fourth. 139. JOURNALS FOR SHAFTS AND AXLES. Length of brass = 9 to 1 length of journal. Less liable to score in wearing, if slight end play can be given. Thickness and projection of collar and radius of curves = d d Coefficient of friction, average '08 = /x. Work expended in friction in foot Ibs. per min. = /t W^dH = -021 Wd E. u Length of journal depends upon the load and speed, length being increased for high speeds. I = l)(Unwin). 58 NOTES IN MECHANICAL ENGINEERING. Increasing diameter increases friction, because the rubbing surface has further to travel in one r evolution. Increasing length does not affect the friction, because for a given space passed through, with a constant load, the friction is independent of surfaces in contact. When an overhanging journal is increased in length the diameter must also be increased slightly, to give same strength as before, D = d \J . Pressure on bearings per square inch longitudinal section may be = ^r ^-. , but o(J + v. ieet mm must never exceed 1000, maximum say 800 in engines. 140. ORDINARY PROPORTIONS OF KEYS. \ diam. of shaft up to 4 inches. Width of key = -- 4 inches to 8 inches. -J 8 inches to 12 inches. Key square at thick end One-third of thickness let in shaft, remainder in wheel. 141. PROPORTIONS OF COTTERS THROUGH BARS. b = Breadth of cotter. t = Thickness of cotter. d = Diameter of bar. Through round bars, 6 = 1-4635(1. * = 1 o Through square bars, side of bar 6 = 1 5 side of bar. t = 4 142. SCREW-CUTTING. Set of change wheels numbers 22 ; increasing by 5 teeth from 20 to 120, two being alike, generally 80 or 90. When 25 in a set, the extra wheels are 130, 140, and 150. NOTES IN MECHANICAL ENGINEERING. 59 Wheels of 10 and 15 teeth are supplied when the screw- cutting gear works the slide rest. Leading screw has usually 2, 3, or 4 threads per inch. .. , leading screw . Double tram must always be used wnen -. T is less screw required than J, generally when less than J. 143. SCREW-CUTTING. To find the wheels for any pitch. Single train Threads per inch in leading screw _ driver Ditto in screw to be cut follower* Double train Threads leading screw _ driver driver Threads screw required follower follower 144. EXAMPLES OF CHANGE WHEELS FOB SCREW-CUTTING. Single trains Leading screw, 4 threads 4 5 _ 20 15 60 Bequired do., 7 7 X 5 " 36' ] X 15 ~ 105 Leading screw, 4 threads _ 16 _1_0 _ 160__.__2 _ 80 Kequired do. 2g 2f ~ 11 X 10 ~ 110 ' 2 ~ 65 Double trains Leading screw, 4 threads 5x4 _ 5x4 _ 50 x 40 _ 50 X 8O Eequired do., | pitch 8 ~~ 2x4 ~ ~20 X 40 ~ 20 X 80 Leading screw, 4 threads 4 2x2_20x20__ 20 x 10 Kequired do., 100 TOO ~~ 5 x 20 ~ 50 x 200 ~ 50 x 10O Trains to be used are shown in broad-faced type. NOTE. Work out same with leading screw of three threads. 145. NOTES ON SPIRAL SPRINGS. Effective No. of coils = generally 2 less than apparent number, owing to flattening at ends for bases. 60 NOTES IN MECHANICAL ENGINEERING. Stroke = effective number of coils x compression or ex- tension of each coil. Pitch of spiral = diameter of steel in inches -f- twice com- pression of one coil under full load, but coils may lie close when spring is for tension only. Diameter of coil = say 8 times diameter of steel. Working load may stretch each coil = J diameter of steel composing spring. To increase stroke add to the number of coils. Spring in tension is more accurate for exact work than one in compression. Best form of section is circular, but square form is stronger, as 10 to 7. 146. SPIRAL SPRINGS. Formula for strength and deflection. E = Compression or extension of one coil in inches. D = Diameter of coil in inches from centre to centre. d = Diameter or side of square of steel composing spring in ^ths f an inch. W = Weight applied in Ibs. c = a constant found by experiment, which may be taken as 22 for round steel and 30 for square steel. E _D 3 W ~ d*c 147. SPIRAL SPRINGS, EANKINE'S FORMULA. d = diameter of wire in inches. c = coefficient of transverse elasticity of wire say 10,500,000 to 12,000,000 for charcoal iron wire, and steel. r = radius to centre of wire in coil. n = effective number of coils. / = greatest safe shearing stress, say 30,000. W = any load not exceeding greatest safe load. NOTES IN MECHANICAL ENGINEERING-. 61 v = corresponding extension or compression. W = greatest safe steady load. v' = greatest safe steady extension or compression. W - = greatest safe sudden load. W _ cd* w , = -196/d 3 v , = 12- 566 nfr* v 64rar 3 r cd W Katio should be ascertained by direct experiment. v Eankines Machinery and Hillworh. 148. DIFFERENTIAL PULLEY CALCULATIONS. W X P - M = modulus or efficiency of machine, then W X M = actual load lifted. By experiment Five cwt. differential pulley block multiplying 16 to 1, coefficient = * 4. 30 cwt. differential pulley block multiplying 53 to 1, co- efficient = -25. NOTE. Load will not lower by itself when M is less than *5. PAKT IV. THE STEAM ENGINE. 149. HORSE-POWEB. Actual H.P. = 33,000 foot-lbs. per minute in all calculations, but the actual work of a horse is about 22,000 foot-lbs. per minute. Nominal H.P. low-pressure engine (pressure 7, IDS, above atmosphere) = d in inches 2 x y stroke in feet -7- 47. 62 NOTES IN MECHANICAL ENGINEEKING. Nominal H.P. high-pressure engine (pressure 21 Ibs. above atmosphere), = N.H.P. low pressure engine X 3. Do. Watt's rule for condensing engines, = d* -4- 28 (22 square inches piston per N.H.P.). Do. Watt's rule for high-pressure, = $ 14= (11 square inches piston per N.H.P.). Admiralty N.H.P. = c?ins. X speed feet per min. -7- 6000. Indicated H.P. = mean p Ibs. square inch, from indicator diagram x area of piston. (x No. of pistons^) X speed in feet per minute -f- 33,000. Effective H.P. = actual H.P. of work done. Nominal H.P. = is a useless commercial term, now becoming obsolete. Boiler H.P. = cubic feet of water evaporated per hour. 150. STEAM wo EKED EXPANSIVELY. When cut off at any part of stroke as '> Then its efficiency = 1 -J- hyp. log. n. Mean pressure = p X - X (1 + hyp. log. n\ IV p Terminal pressure = - All pressures are measured from perfect vacuum. Above formulae assume theoretically perfect indicator diagrams and expansion according to Boyle and Marriott's law. 151. CEANK AND PISTON NOTES. a Length of connecting rod. Z> = Length of crank. sc = Distance of piston, from end of stroke furthest from crank, when point of maximum leverage is reached. NOTES IN MECHANICAL ENGINEERING. 63 x' = Distance of piston as before, when crank has made quarter revolution from dead centre. a- = ( a + 1) - VV + & 2 0' = (a + 6) - A/a 2 - 6 2 . These values divided respectively by 26 will give the proportion of stroke where these points occur. All the distances are measured from the end of stroke furthest from crank. 152. LINK MOTIONS. StepJienson's. Link curved, concave side towards eccen- trics, shifted to vary position of motion block, block moving in direct line with slide rod, lead increasing towards mid- gear with open rods and decreasing with crossed rods. Gooctis. Link curved, concave side towards spindle, maintained in central position by rod swinging on a stud, motion block shifted in link by radius rod connected to valve spindle', lead constant. Allans. Link straight, link and motion block moved in opposite directions by rocking shaft, lead increasing towards mid- gear with open rods, and decreasing with crossed rods. 153. NOTES ON CALCULATION OF ENGINE SHAFTS. By law of virtual velocities, mean pressure on crank pin 2 s d 2 in a m = X 2 ' " 1-57' but the force being irregular, the maximum must be taken for the crank and fly wheel shaft ; say full pressure on piston acting at radius of crank, . s at radius - Beyond the fly-wheel may be substituted for j^ 1 as the strain will there be practically uniform. 64 NOTES IN MECHANICAL ENGINEERING. 154. CALCULATION OF ENGINE SHAFTS. p = maximum boiler pressure, Ibs. per square inch. m = mean pressure in cylinder s = stroke of piston in feet. d = diameter inches. a = area square inches. / = factor of safety. Hyde. eng. and Steam engine. stm. winches. Wrought iron and steel . . - . . T V Cast iron . . . . yV rV It, = ultimate strength, 1-inch bar, 1 foot radius. Cast steel. Mild steel. Wrought iron. Cast iron. 1250 1000 750 600 c = constant or safe load - fk. Steam engine .. 200 175 125 60 Hydraulic engine, &c. 125 100 75 40 D = diameter of shaft in inches. For crank shaft : 3 /d 2 X * X p X s _ s/d 2 p s D ~~ V T~x~2~x/x * V2-5c' And beyond fly-wheel : -. _ 3 /~~d* X m, X s s /d*ms ~ V 2~x~2~x/"xfc - V Tc~ ' For 2 cylinders, let diameter = D + 15 D. For 3 cylinders = D + * 3 D. 155. STEENGTH OF CRANK PIN. p = uniformly distributed load in Ibs. I = length of journal in inches. d = diameter of journal in inches. NOTES IN MECHANICAL ENGINEERING. 65 f = greatest safe stress per square inch, say, wrought iron 6000 to 9000. steel .. .. 9000 to 13500. cast iron .. 3000 to 4500. = greatest bending moment at fixed end of journal. a M = go ^ 3 = '0982 d? = modulus of circular sec. = j I = M^ =-r^ 3 X i d* = -0491 ft = moment of ^ O-J OA inertia of circular section. I ^ 3/5a P j B 64 V 1964/ V / 156. DEFINITIONS RELATING TO SCREW PROPELLERS. Length = A 1 B 1 measured along the axis of the shaft. Angle = P H, which is a plane triangle when developed. Pitch = The distance traversed on A 1 B 1 for one complete revolution of A 1 P. Slip The difference between the theoretical forward motion, calculated from the pitch of the screw, and the actual progress of the ship. Area = A 1 P O B, surface of blade in square feet. Thread or Helix = Outer edge of blade, P. Diameter = Diameter of cylinder circumscribing the thread of screw. A 1 P = radius. 157. NOTES ON SCREW PROPELLERS. In the common form of propeller the screw surface is generated by a line perpendicular to the axis of the shaft revolving round the shaft and progressing uniformly along it. Screw surfaces are also generated by a line at right angles to a conical surface; in some cases the vertex of the cone points aft, and in others forward. In some the surface is F 66 NOTES IN MECHANICAL ENGINEERING. traced out by a line perpendicular to a sphere. The object in such cases being to diminish, if possible, centrifugal action of the water. 'Screws of same pitch have different angles if their diameters differ. Angle reducing as diameter increases. The screws are either right or left-handed, and may have two, three, or four blades. 158. SLIP OF SCREW PROPELLER. Slip is less when pitch is small and speed great, but more danger from heated bearings. When pitch is small, the propeller is less liable to break from a blow. The slip is diminished, cseteris paribus, by 1. Decreasing the angle of the screw. 2. Increasing the diameter of the screw. 3. Increasing the length of the screw. But the friction increases rapidly with the surface of the blade. The indicated horse power varies as the square of the speed of the ship x number of revolutions of screw x pitch. The most economical speed is when the vessel steams half as fast again as the opposing current, or half as fast again as a vessel it desires to overtake. 159. PITCH OP SCREW PROPELLER. Ordinary propellers have the pitch uniform throughout each blade, the angle varying with the distance from the axis, originally known as Smith's propeller. Screws of increasing pitch are sometimes used, and known as Woodcroft's propeller. Propellers with two blades are common in large ships, but those with three or four blades are better when the draft is small or in a rough sea. Feathering-screws have the blades pivoted so that the angle, and thereby the pitch, may be altered. The pitch of a screw varies with the ratio of the circle described by the screw to the immersed midship section. NOTES IN MECHANICAL ENGINEERING. PART V. BOILERS AND BOILER FITTINGS. 160. SENSIBLE HEAT. The Temperature of a body is its state with regard to sensible heat. For purposes of measurement some definite effect produced by heat must be selected, e. g. the alteration in length or volume of a substance which expands and contracts uniformly when heated or cooled. At all ordinary temperatures the ratio of increment in volume to increment in absolute temperature is practically constant in the case of mercury, it is moreover a liquid at such temperatures, and easily measured ; hence the Mercu- rial Thermometer is that most commonly used for determining the temperature of a body. 161. COMPARISON OP THERMOMETERS. No. of Degrees between Freezing and Boiling Point Absolute Zero of Temper- ature. Freezing Point of Water. Point of maximum Density of Water. Boiling Point of Water. of Water. Great Britain and America : Fahrenheit = F. .. 180 -461-2 32 39-1 212 France and part of Continent : Centigrade = C. .. 100 -271 4 100 Germany : Reaumur = R. 80 -219-2 3-2 80 . . 9 F. = 5 C. = 4 R. To convert from one scale to another, F = | C + 32, C = (F 32), E = R + 32, C = | R, = -J(F 32) F 2 68 NOTES IN MECHANICAL ENGINEEKING. 162. TKANSFER OF HEAT. Radiation of heat is the transfer which takes place between bodies at all distances apart, in the same manner and according to the same laws as the radiation of light. Conduction is the transfer of heat between two bodies, or parts of a body, which touch each other. Convection, or carrying of heat, means the transfer and diffusion of the state of heat in a fluid mass by means of the motion of the particles of that mass. 163. MECHANICAL EQUIVALENT OF HEAT. British Thermal Unit, or unit of heat, is the quantity of heat required to raise 1 Ib. of pure water, at its point of maximum density (=39-1 F.), through 1 F. Joules Equivalent is the mechanical effect resident in one thermal unit = 772 foot-lbs. When the centigrade scale is used, the point of maximum density of water will be 4 C., the thermal unit the quantity of heat required to raise 1 Ib. water through 1 C., and its mechanical equivalent 1390 foot-lbs. 164. THERMODYNAMICS. First Law of Thermodynamics Heat and mechanical energy are mutually convertible ; and heat requires for its production and produces by its disappearance, mechanical energy in the proportion of 772 foot-lbs. for each British unit of heat. Second Law of Thermodynamics. If the total actual heat of a homogeneous and uniformly hot substance be conceived to be divided into any number of equal parts, the effects of these parts in causing work to be performed are equal. 165. CAPACITY OF BODIES FOR HEAT. Capacity for heat of a body is the number of units of heat required to raise one pound weight of the body one degree in temperature. NOTES IN MECHANICAL ENGINEERING. 69 The Specific heat of a body is its capacity for heat com- pared with that of an equal weight of water. Latent heat is the heat absorbed or disengaged by a body without alteration of temperature, upon a change of state or alteration in the aggregation of its molecules. 166. LATENT AND SENSIBLE HEAT. Dr. Black's theory of the latent and sensible heat of steam was that the sum of the two was constant at all temperatures. Regnault's experiments showed that the total heat was not constant, but increased slowly with increase of temperature, and was equal in F. to (Sensible temperature in F. X * 305) + 1082. 167. GASES AND VAPOURS. Permanent gases are those which cannot be liquefied. Ordinary gases are those which do not liquefy at ordinary temperatures or pressures, and the farther they are removed from their point of liquefaction the nearer they approach the character of permanent gases. Vapours are gases near their point of liquefaction. Ordi- nary high or low pressure steam is a vapour, superheated steam is a gas. The temperature being constant, the volume of a gas is inversely as its pressure (Boyle's Law). When a gas is heated, the expansion is about ir | 7 of its volume at C. for each C. increase of temperature. 168. ATMOSPHERIC PRESSURE. The weight of the atmosphere at 60 Fahr. and 30 ins. barometric pressure is 14*6757 Ibs. per square inch. No. of atmos. x '006557 = tons per square inch. Absolute pressure is the pressure from zero, or the pressure of the atmosphere added to the indication of the pressure gauge, say gauge pressure + 15 Ibs. 70 NOTES IN MECHANICAL ENGINEERING. All questions of expansion and compression of steam must be worked from absolute pressure or perfect vacuum line of indicator diagram. 169. PROPERTIES OF SATURATED STEAM. Absolute Pressure. Gauge Pressure. Sensible Temper- ature. Latent Heat. Total Heat. Weight of Cub. Foot. Relative Volume. 14-7 0-0 212-0 966-1 1178-1 0380 1642 65 50-3 298-0 906-3 1201-3 1538 405 70 55-3 302-9 902-9 1205-8 1648 378 75 60-3 307-5 899-7 1207-2 1759 353 90 75-3 320-2 890-9 1211-1 2089 298 115 100-3 338-0 878-5 1216-5 2628 237 170. EXPERIMENTS ON EVAPORATION IN BOILERS. Class. Size. Lbs. Water per Ib. Coal. Lbs. Coal per cub. foot Water. Cornish 20 H.P. 6-764 9-212 Lancashire 25 7-547 8-256 Galloway 35 9'5 6-579 Field .. .. 10-9 5-734 171. EVAPORATIVE VALUE AT DIFFERENT TEMPERATURES. In stating the evaporative power of a boiler it is usual to express it in terms of feed- water evaporated from 212. t actual temperature of feed-water. T = total heat of steam under given pressure. c = cubic foot of water evaporated from t. C = from 212 by same quantity of heat. T t = heat imparted. T t NOTES IN MECHANICAL ENGINEERING. 71 172. Loss OP HEAT IN BOILERS. Assuming that it requires 10 Ibs. of coal to evaporate 1 cubic foot of water from 60 into steam at 60 Ibs. per square inch gauge pressure, the loss of heat may be shown, as follows, to be about 50 per cent : Total heat of combustion in 1 Ib. of coal in British thermal units = 14,700. 14,700 units per Ib. x 10 Ibs. coal .. .. =147,000 Steam at 60 Ibs. pressure has a total heat of 1207 units, 1207 - 60 temp, of feed- water = 1147 units per Ib. of water. 1 cub. foot water = 62 -5 Ibs. 62-5x1147 = 71,687 Loss in chimney, 24 Ibs. air, required to burn 1 Ib. coal. 24 x 10 = 240 Ibs. to burn 10 Ibs. coal. Specific heat of air = 2374, temperature of escaping gases = 600. 240 x '2374 x 600 = 34,185 Loss in hot ashes, fuel dropped through, &c., say 10 per cent, of total heat = 14,700 Loss by radiation and conduction, say 10 per cent = 14,700 Loss by imperfect combustion, say 7J per cent. = 11 ,025 146,297 173. HEAT IN BOILER FURNACES. (1) Temperature of furnace, say about 2500 F. (2) of escaping gases, say 600 to 1200 F. (3) steam and water in boiler, say 300 F. (4) ., water in condenser, say 100 F. Difference between (1) and (2) is absorbed by the water in raising its temperature, by the steam as latent heat, and by the air entering furnace in excess of quantity required for combustion. 72 NOTES IN MECHANICAL ENGINEERING. Difference between (2) and (3) is utilised in creating draught ; 600 is the most economical temperature of escaping gases as it allows sufficient difference of temperature for rapid passage of heat to water, and the density is sufficiently reduced to give rapid ascending current in chimney shaft. Difference between (3) and (4) is utilised in the engine. The difference of temperature or quantity of sensible heat does not by itself represent the comparative efficiency. See article 172. 174. COAL BUENT PER SQUARE FOOT OF FIRE-GRATE. Ibs. per hour. Cornish boilers for pumping engines .. 4 to 10 and others for factory uses .. 10 15 Marine boilers, ordinary rates .. .. 15 20 Boilers with strong chimney draught .. 20 30 Locomotives 60 120 175. COMBUSTION OF FUEL. Two to three Ibs. oxygen = 120 to 180 cubic feet of air required to burn 1 Ib. of coal, or, assuming only frds effective 180 to 270 cubic feet will be required. Air and smoke together equal about 2000 cubic feet per cubic foot water evaporated, temperature say 800 Fahr. Area of fire-grate = 1 square foot per N.H.P. heating surface = 1 square yard per N.H.P. Cubic feet evaporated per hour = N.H.P. of boiler. Steam space of boiler = quantity required for one revolu- tion of engine X 10. Water space = 5 to 10 cubic feet per N.H.P. Area of chimney in square inches = 2 X 112 X N.H.P. or cubic foot per hour VHeight. 73 NOTES IN MECHANICAL ENGINEERINGS 176. HORSE-POWER OP BOILERS. S = heating surface in square yards. g = grate surface in square feet. H.P = c (S + g) c = 1 for ordinary coal. ,, good steam coal. -J best coal only. It. Armstrong. a = area in sq. ft. of water surface in boiler -f- horizontal sectional area of furnace tube in Cornish or Lancashire boiler. H.P. = Plain cylindrical boiler . . a 6" Vs^r Cornish or Lancashire boiler . . a IS 6 to 8 d Galloway boiler Multitubular boiler <7 JtoiB I'S \/S<7 5 to -8 Marine boiler (I.H.P. = 5 N.H.P. ' 7VSJ The average number of cubic feet water evaporated per hour from cold feed with ordinary firing and good steam coal, is generally taken as the nominal H.P. of boiler, but half a cubic foot is sufficient to develop 1 indicated H.P. in most steam-engines. 177. BOILER FURNACES. With bituminous fuel the layer in the furnace should be about 6 inches thick, and should never exceed 12 inches NOTES IN MECHANICAL ENGINEERING. Thin firing is more economical, but requires more careful stoking. Fresh fuel should be put in front of the fire and the red-hot fuel pushed back, or should be spread thinly over the surface after the hollows are filled up. With coke or hard coal the fire may be thicker, especially if a blast be used. 178. HEATING SURFACE OF BOILERS. Class. Proportion of Heating Surface to Grate Surface. Heating Surface to Evaporation, 1 cubic foot per hour. Plain cylindrical Cornish and Lancashire . . Multitubular Locomotive 10-16 to 1 15-25 to 1 30-10 to 1 60-80 to 1 square feet 18 14 9 6 179. COMPARATIVE VALUE OF HEATING SURFACES. Area of shell exposed to flame = 1. Horizontal area above flame =1. Surface inclined towards flame = 1. Vertical surface = 1. Surface inclined from flame = 0. Horizontal surface below flame = 0. Internal cylindrical flues = \ circumference. Small tubes = f 180. FIRE-BARS Should not exceed 3 feet in length. Ordinary furnaces should not exceed 6 feet in length, the bars in two lengths. Dead-plate should be 9 to 15 inches wide. Fire-bars say 3 feet long, 3 inches deep in middle, f inch thick at top, tapered to f inch thick at bottom ; bevelled one end to rest on dead-plate, to allow for expansion, and notched at other to rest on wrought iron bearer: if notched both ends there should be not less than 1-inch play. Chipping faces or dis- NOTES IN MECHANICAL ENGINEERING. 75 tance pieces on bars should be made at both ends and middle. Air spaces between bars f inch to -f inch, usually |- inch. The fire-grate should incline downwards towards the back, J inch to inch per foot. Passage above bridge = one-sixth area of grate. Perforations in furnace door f inch to J inch diameter, total area from 2 to 5 square inches per square foot fire-grate. 181. BOILER TUBES. Class of Boiler. Ratio, Length to Diameter. Ratio, Tube Area to Grate Area. Multitubular boilers, with chimney"! draught I 24tol 1 to 7 Locomotive boilers Small marine boilers, with high-"! pressure engines / Large marine boilers, with condensing! 120 to 1 33 to 1 20tol 1 to 4 1 to 6 Ito3 1 square foot of fire-box is equal to 3 square feet tube sur- face : J diameter should be left between the tubes for circu- lation and escape of steam. Heating surface of small tubes = of circumference, of furnace tubes = ^ circumference. 182. TAPER OF PLUGS FOR BOILER-COCKS. For pressures up to 30 Ibs. per square inch, a taper of in 8 on each side is found to work well, but for pressures of about 100 Ibs. a taper of 1 in 12 is necessary to insure tightness. Say 1 in 10 minimum for pressure of 60 Ibs. 183. BOILER BEATINGS. With old form of wheel draft the boiler was set on a mid- feather: this is the worst possible arrangement. Should be set on fireclay blocks forming side walls, the resting surfaces not wider than -^tla. diameter of boiler. 76 NOTES IN MECHANICAL ENGINEERING. Flues should be large enough for a man' to pass entirely round, area should be kept as uniform as possible, corners rounded, and angles filled up. Externally fired boilers are frequently set with flash flues, i. e. the gases pass directly from furnace, over the bridge, and along bottom of boiler, to chimney. Boilers should be set with a fall of about 1 in 200 or -^ inch per foot towards front. 184. SIZE OF FACTORY CHIMNEY FOR BOILERS. W = weight of coal burnt in Ibs. per hour. A = area of chimney in square feet at top. H = height of chimney in feet. W = 14 A V H H Chimney for single boiler, area = -J fire-grate. Do. under 150 feet high I l for more than one \ " ~ T1E5 " Do. over 150 feet high do. = -^ , . . . , Ibs. coal per hour x 12 Area of chimney in square inches = .. . . - - . fj height feet Bourne. Area of chimney usually -fa area of fire-grate and 40 feet high. Scott Russell. 20 square inches area per N.H.P. of engine. Height about 20 times internal diameter. Flues -^ area of fire-grate, diminishing to j 1 ^ at chimney. Height of chimney = 45 feet. area fire-grate Area of chimney = ^ ht ^ 1-53 Elswick. Ordinary velocity of gases in chimney shaft = 2 4 J H. Most economical temperature of escaping gases =600 Fahr. NOTES IN MECHANICAL ENGINEEKING. 77 At this temperature the volume of air entering furnace is doubled on exit. A cubic foot of water requires 10 Ibs. coal to evaporate it ; 10 Ibs. coal require 210 Ibs. air for complete combustion, = say 2750 cubic feet. 185. BRICK CHIMNEY-SHAFTS. The bond usually adopted is 1 course of headers to 4 of stretchers. Up to 120 feet high the top length is generally one brick thick ; above that height, top length 1^ brick thick. Height of any length of uniform section should not exceed 90 feet, and should be less in thin sections. Outside diameter at ground line should not be less than T Lth the height. 45 feet is an ordinary height for two steam boilers, but in some towns, as Manchester and Leeds, the minimum height allowed is 90 feet. 186. SEA-WATER. Proportion of salt in water of open sea, 32 to 38 parts per 1000; Eed Sea 43, Baltic 6 -6, Black Sea 21, Arctic Ocean 28-5 British Channel 35-5, Mediterranean 38. Ure. Average specific gravity of sea- water 1 027, pure distilled water being 1. Salts contained per 1000 : Chloride of Sodium 25 parts, Muriate of magnesia 3, Sulphate of magnesia 2 Sulphate of lime 1, others 1, total 32. Faraday. Weight of one cubic foot, about 64 14 Ibs. 187. BOILER INCRUSTATION. Order of deposition of impurities as water becomes concen- trated : 1. Carbonate of lime. 2. Sulphate of lime. /^Rt F Sf 78 NOTES IN MECHANICAL ENGINEERING. 3. Salts of iron, as bases or oxides, and some of these of magnesia. 4. The silica or alumina, usually with more or less of organic matter. 5. Common salt. M. Couste. 188. To CALCULATE SIZE OF BOILER. Say Cornish boiler for high-pressure engine : d = diameter of cylinder in inches. s = stroke in inches. B = revolutions per minute. r = ratio of cut-off. . p = boiler pressure, Ibs. per square inch by gauge. n = number of cylinders. S = cubic feet steam required per hour, allowing 25 per cent, for contingencies. S = l-25d 2 s-2wK60 = say v = relative volume of steam at p pressure. W = weight of water to be evaporated in Ibs. per hour. c = combustion of coal in Ibs. per square foot fire-grate per hour, say for Cornish boiler = 12 Ibs. e = evaporation in Ibs. of water from 60 Fahr. per Ib. of coal, say for Cornish boiler = 7 Ibs. c X e = Ibs. water evaporated per square foot fire-grate per hour. A = area of fire-grate in square feet. ce I = length of fire-grate in feet, say 4-5 to 5*5. w = width v>=~+ '166. NOTES IN MECHANICAL ENGINEERING. 79 D = diameter of boiler shell = 2 w. L = length of =4 D. When w exceeds 3*25, make two Cornish boilers or one Lancashire. For latter, D = 2J w (10 being width of one furnace). 189. To CALCULATE SAFETY-VALVE LEVERAGE. a = area of valve in square inches. p = gauge pressure in Ibs. per square inch. W= weight on end of lever in Ibs. w = weight of lever in Ibs. w' = weight of valve in Ibs. L = distance between weight and fulcrum in inches. g = do. centre of gravity of lever and do. Z = do. valve centre and do. w = W n JL. W T, + w' 190. ULTIMATE STRENGTH OF BOILER-SHELL. Longitudinal strength : pdl = 2 tlc.'.pd = 2tc. Ztc pd *=-*- '."f; Transverse strength : divide by -= > then 80 KOTES IN MECHANICAL ENGINEERING-. but -r- will rarely exceed '01, and may therefore be omitted. d 4:tc p d - - or the transverse strength is double the longitudinal. 191. COLLAPSING PRESSURE OF BOILER-TUBES. Length not exceeding 15 diameters. Cylindrical : p = 33 61 x QJJ!1 Fairbairn. L d or log p = 1-5265 + 2- 19 log. 100 - logLd; or approximately, _ 800,000 t* P '' ~Ld~' Elliptical : p = ^0,000*^ r = radius of natter curve. L(2r) = 800,000^ x 2D'. D ^ aretlietwodiameters Li d in inches. 192. BOILERS COMPARISON BETWEEN BURSTING AND COLLAPSING PRESSURES. P = internal or bursting pressure in Ibs. per square inch. p = external or collapsing c = ultimate strength of single rivetted joint = say 30,000 Ibs. I = length of unsupported cylindrical tube in feet. D = diameter of boiler in inches. d = tube T = thickness of shell plate in inches. t = tube NOTES IN MECHANICAL ENGINEERING. 81 E = ratio of tube diameter to shell diameter = -=- 2Tc _ 60,000 T 800,000 P * = ~ TT- P _ 60.000 Tld __ TZE p ~ SOpOO iFD ~ WW? .-. When P = p, then I = ^-| 193. FACTOR OF SAFETY, STEAM BOILERS. Test pressure = ultimate strength. Working pressure, if under periodical inspection, = % do. Working pressure, if not under independent inspection, TESTING BOILERS. Government Yards. New boilers to be tested to three times their working pressure. Boilers in use not to be worked more than 300 hours without being laid off for examination. To be tested periodically to twice their working pressure. Best private practice. New boilers to be tested to twice their working pressure. Boilers in use not to be worked more than 1000 hours without being laid off for examination. To be tested after repairs to 1^ times their working pressure. 195. DUTY OF ENGINES. s = Standard of comparison in Ibs. : Cvvt. any coal .. .. 112 Ibs. Bushel Welsh coal .. 94 Newcastle coal . . 84 10 = Ibs. wt. coal burnt per I.H.P. per hour. n - no. of cwts. or bushels burnt per hour. G 82 NOTES IN MECHANICAL ENGINEERING. Duty in ft,lb S . per standard = mj. X 83.000 x 60^ T, 33,000 x 60 x 8 JUO. = . 991 7T Duty in million ft.-lbs. per cwt. = . w Cornish duty : g = gallons of water pumped per hour. / = feet lift of water pumped. Duty = W ?/ n 196. STEAM PIPES. Thickness between 2" and 12" diameter and up to 70 ILs boiler pressure, cast iron, d + 4 = t in Tgths of an inch ; for exhaust steam, suction, and ordinary low pressure pipes, cast iron, d + 10 = t in ^nds of an inch. PAET VI. HYDRAULIC MACHINERY. 197. SUMMARY OF HYDRAULICS. THE quantities discharged from different apertures of simi- lar character vary directly as the areas, and as *J altitudes. On account of friction, a small orifice discharges propor- tionally less water ; and of several orifices having the same area, that with the smallest perimeter discharges most : hence a circular orifice is the most advantageous. NOTES IN MECHANICAL ENGINEERING. 83 Water issuing from a circular aperture is contracted at [Bossut -666) distance of J diameter from orifice, from 1 to! Venturi 631 > (Eytelwein-64 J in area, called " vena contracta." Vein contracts more with greater head, therefore discharge slightly diminished below theoretical discharge due to altitude. The discharge through a tube of diameter = length is the same as through simple orifice of equal diameter. The dis- charge increases up to a length of 4 diameters. The discharges through horizontal conduit pipes are directly as the altitudes and inversely as *J length. To have perceptible and continuous discharge, head must not be less than ^ . Vertical bends discharge less water than hori- ~ zontal, and horizontal bends less than straight pipes. In prismatic vessels twice as much is discharged from the same orifice if the vessel be kept full, during the time it would take to empty itself. 198. COMPARISON OP DISCHARGE THROUGH VARIOUS APERTURES. Theoretical velocity in feet per second = ^/ Head inii^x^g. Theoretical discharge being 1 , Short tube projecting into reservoir = 5. Orifice in thin plate, 1" diameter = 62. Tube 2 diameters long = 82. Conical tube approaching form of contracted vein = 92. Do. edges rounded off = -98. 199. USEFUL NUMBERS IN CONNECTION WITH WATER. A standard or imperial gallon of water was formerly 277-274 cubic inches, is now lOlbs. avoirdupois at 62Fahr. and 30" bar. = 277-123 cubic inches or -1G0372 cubic feet. Capt. K M. Shaw. G 2 I NOTES IN MECHANICAL ENGINEERING. Cubic feet per minute x 9000 = gallons per 24 hours. Head in feet x * 434 = Ibs. per square inch. Lbs. per square inch x 2 3 = foot-head. Tons x 224 = gallons. Diameter inches 2 -7- 10 = gallons per yard. 200. DISCHARGE THROUGH PIPES FROM NATURAL HEAD. H = head of water in ft L = length of pipe iu ft d = diam. of pipe in inches . . e constant (see Table) W = cub. ft. discharged per min. c d. c. d. c. 1 H H 2 2* 3 4 5 6 4-71 8-48 13-02 26-69 46-67 73-50 151-02 263-87 416-54 7 8 9 10 12 15 18 24 30 612-32 854-99 1147-61 1493-47 2356 00 4115-93 6493-14 13328-0 23282-0 W = /L YH Beardmore. 10 to 12 feet head is absorbed in friction per mile of pipe. Bateman. 201. HYDRAULIC PRESSURE ACCUMULATOR, Invented r by Sir W. G. Armstrong in 1850, consists of vertical cylinder and ram, to the crosshead of which a load of 20 to 120 tons is hung to create the pressure necessary for working the machinery, obviating the use of a high tower giving a natural head of water. The load is usually contained in a cylindrical casing. Clean washed heavy Thames ballast weighing 27 cwt. per cubic yard is the cheapest and best procurable in London. Where convenient, railway ballast may be used. Iron slag is sometimes used : it has the advantage of weight, and there- fore occupies less space, but is expensive and very awkward to handle. Copper ore slag is not suitable, owing to tho NOTES IN MECHANICAL ENGINEERING. 85 galvanic action set up. "Water lias been used for ballast where the pressure is required to be varied occasionally. Clay has also been used in its natural state, but is better when burnt. Iron kentledge, brickwork, cast-iron blocks and direct steam pressure have also been used by various manufacturers for producing the load. 202. PRESSURE IN PIPE-MAINS. Working pressure averages 700 Ibs. per square inch when given by Accumulator, but may be from 350 Ibs. to 1000 Ibs. 700 Ibs. per square inch = 549*78 Ibs. per circular inch, equivalent to 1613*2 feet-head. All pipes subject to the Accumulator pressure to be tested to 2,500 Ibs. per square inch before leaving the works, and to 2000 Ibs. per square inch after being laid. Water companies' pipes to be tested with a pressure equal to 500 feet-head, and while under pressure to be sounded from end to end with a 5-lb. hammer, Pressure in water companies' mains is at maximum between 2 and 3 A.M., minimum 6 A.M. to 6 P.M., variation say from 10 to 60 Ibs. per square inch. 203. VARIATION OP ACCUMULATOR PRESSURE DUE TO WORKING OF MACHINERY. Normal pressure, say 700 Ibs. per square inch. Average variation, from 50 Ibs. below to 100 Ibs. above the normal pressure. Maximum variation, 250 Ibs. above and below, but this only occurs on a long line of pipe where the Accumulator is at some distance from the machine. 204. FRICTION OF ACCUMULATORS. P = pressure in Ibs. per square inch taken at half stroke, Accumulator rising slowly. p = pressure in Ibs. per square inch, Accumulator falling slowly. 86 NOTES IN MECHANICAL ENGINEERING. / = friction of ram in Ibs. per square inch. At the Marseilles Docks the friction of a 17-inch Accu- mulator amounted to 7*355 Ibs. per square inch, or not quite 1 per cent, of the gross load. Hawthorn. At Scottish Wharf the friction of a 17-inch Accumulator was 10 Ibs. per square inch. 205. AIR ACCUMULATORS. W = working capacity in cubic feet of water. C = mean capacity for air in cubic feet. a = cubic feet air required at atmospheric pressure to charge Accumulator. p = mean pressure in Ibs. per square inch. P = maximum P' = minimum P - P P' - P W~ W" 1 - I-UJL; 20 r 2C P'W p = 2(p-P) C 15' May be proportioned as follows : D = inside diameter in feet. L = inside length in feet. D = #-4244W L = 11D C Total capacity divided thus : Air under maximum pressure .. .. Water .. .. Margin from level of outlet to lowest water level ............ Ifp = 700, then P = 840 and P' = 600. NOTES IN MECHANICAL ENGINEERING-. 87 206. VELOCITY OF WATER THROUGH PIPES AND VALVES. With an Accumulator pressure of 700 Ibs. per square inch, the natural velocity (theoretical) is 322 32 feet per second. It is found in practice that not more than y^th of this can be obtained through the pipes and ^rd through the valves, in order to maintain the proper speed of the machinery. The loss from friction in the pipes is about 1 Ib. per square inch per 100 feet length, after they have been laid some time. In order to allow for the furring-up of the small pipes, it is not safe to reckon upon more than three times the dia- meter of pipe in inches as the velocity obtainable in feet per second. It is also usual to calculate the velocity through the valves at not more than 98 feet per second. 207. DELIVERY OF WATER IN PIPES. v = velocity in feet per second through pipe. a = area of pipe in square inches. d = diameter of pipes in inches. W = discharge in cubic feet per minute. Approximately : 208. THICKNESS OP HYDRAULIC PIPES. For Accumulator pressure of 700 Ibs. per square inch: Inside diameter in inches -f- 2 = thickness of metal in ^ths. Filling pipes made by local firms, -fa inch thicker. 88 NOTES IN MECHANICAL ENGINEERING. 209. STRAIN ALLOWED ON WROUGHT IKON IN HYDRAULIC CRANES. Tons per square inch. Tension. Compression. Ballast and coaling cranes . . 2 J 1 Warehouse and other cranes lifting from 1 to 5 tons ...... 3 2 Cranes lifting more than 5 tons 3J 3 210. EFFECTIVE PRESSURE FOR HYDRAULIC CRANES AND HOISTS. p = Accumulator pressure in Ibs. per square inch. m = ratio of multiplying power. E = effective pressure in Ibs. per square inch, including all allowances for friction. E =_p(-84- -02m). 211. SPEED OF LIFTING WITH HYDRAULIC POWER. Warehouse cranes and jiggers, 6 feet per second. Platform cranes and small luggage lifts, 4 feet per second. Passenger and waggon hoists, 2 feet per second. Maximum speed under any circumstances, 10 feet per second. Warehouse cranes, other formulae. W = load in tons. li = height of lift in feet. v = velocity in feet per second. 212. LIFTING EAMS FOR HYDRAULIC CRANES. W = load to be lifted in Ibs. w weight of ram, crosshead, sheaves, and chain. I - height of lift in feet. NOTES IN MECHANICAL ENGINEERING. 89 m = multiplying power. c = coefficient of effect = 84 02 m. a area of ram in square inches. s = stroke of ram in inches. p = Accumulator pressure in Ibs. per square inch. C = capacity of cylinder in cubic feet. For horizontal cylinders : a __ Wm C=_^- pC 14:4: pC* For vertical cylinders : a = C = =-T-J . P C 14:4: p C For inverted cylinders : __ Wm -w Q = Wl-ws P c 213. TURNING KAMS FOE HYDKAULIO CRANES. W = load in tons. R = rake in feet. / = length between bearings in feet. d = diameter of turning drum in feet. p = Accumulator pressure, Ibs. per square inch. m = multiplying power of turning cylinder (usually 2 tol). a = area of turning ram in square inches. Alternative formulae : 120WR 2 m SOOOWRm ft . d B I dp I dp a= (5906^-?) -3-3. V Idp ) 90 NOTES IN MECHANICAL ENGINEEKING. 214. AREAS OF VALVES FOR MACHINERY UNDER ACCUMULATOR PRESSURE. A = area of lifting ram. m = ratio of multiplying power. v = velocity of load in feet per second. V = velocity of water through valve, feet per second. W = weight of ram, crosshead, sheaves, chain, &c. in Ibs. a = area of lifting valve (mitred spindle). a 1 = area of lowering valve (mitred spindle). A v _,_ _ At? a = ~ - a = W When cylinder is horizontal, then -- = area of return- ing ram. 215. AREAS OF PORTS IN SLIDE VALVES. v = velocity of load in feet per second. m = ratio of multiplying power. A = area of ram in square inches. Area of pressure port = -^- (opening side, V-shaped). Area of exhaust port = 98m 216. DIAPHRAGM REGULATOR FOR HYDRAULIC MACHINERY. When a hydraulic crane or hoist works too quickly, and it is desired to reduce the speed to a safe limit, it is usual to partially close the stop valve ; but when there is a risk of this being interfered with, a brass diaphragm, ^th diameter thick and about ^ inch at edge, is placed in a pipe joint near the working valves. The hole in the diaphragm should be tapered, the small side being next to the machine. To find size : NOTES IN MECHANICAL ENGINEERING-. 91 A = area of lifting ram, square inches. m = ratio of multiplying power. s = speed of lifting chain with, full load foot second. p = accumulator pressure, Ibs. square inch. a = area of small side of hole (large side = twice dia- meter of small side). As ~ 217. COUNTERWEIGHTS FOE CRANE CHAINS. The overhauling weights should be oval, i. e. egg-shaped, with small end on top to avoid catching under beams, &e. Hole for chain should be -J- inch larger than cross section of links, and interior should be cored out to J- inch clear all round. The approximate weight of counterbalance required is t 218. MECHANICAL VALUE OF FLUIDS UNDER PRESSURE. U = units of useful work in foot-lbs. p = pressure in Ibs. per square inch. Q = quantity used in cubic feet. M = modulus of machine, or coefficient of effect found by experiment, and varying with class of machine or arrangement. 219. MECHANICAL VALUE OF WATER UNDER ACCUMULATOR PRESSURE. Theoretically the mechanical value of water under Acer. pressure of 700 Ibs. per square inch (549 78, say 550 Ibs. per circular inch) is 100,800 foot-lbs., or 45 foot-tons per cubic foot of water, irrespective of the time in which it is consumed ; or 3 0545 H.P. per cubic foot per minute ; or 1 H.P. requires 32738 cubic feet per minute. 92 NOTES IN MECHANICAL ENGINEERING. Approximately this equals 1 H.P. from 2 gallons of water ; but practically, allowing for all losses, about 3J gallons are required, or 4 cubic feet will give out 100 foot-tons in work. 220. POWER REQUIRED TO WORK HYDRAULIC MACHINERY. In hotels, wharves, &c., with several machines, allowance must be made for f of the machinery working to half the full height every 1J minute. .*. power per minute = -| total capacity of machinery. At wharf with several cranes, f machinery full lift, every 1J minute. .*. power per minute = f capacity of machinery. At railway goods stations, docks, &c., where many machines are idle at one time, say 1 machinery full height, every 1J minute. . * . power = -jL. capacity of machinery. At small wharves where cranes are rapidly worked, all machinery, full height, every 1J minute. .*. power = |- capacity of machinery. 221. PACKING FOR FORCE PUMPS. Cup-leathers may be single, double, or treble. If single, the open end should be turned towards the delivery end of the pump. If double, they may be back to back or both turned towards delivery end of pump. If treble, two should "be back to back, and the third put as a duplicate to the one turned towards delivery end. In all cases the back of the leather should be closely supported by a washer curved to the shape of the leather. Double leathers back to back are generally used, and last from 2 days to 4 months, average say 1 month. Only the middle of the back of best oil- dressed hide is used. Spun-yarn is sometimes used the same as for glands of NOTES IN MECHANICAL ENGINEERING. 93 hydraulic machinery generally. It is plaited and formed into rings by splicing, soaked in tallow, and screwed up in a mould to form solid rings of exact size to fit pump. Hope is sometimes used in the same way, being selected of the exact diameter required. The two latter methods are said to last from 4 to 6 months, but there is probably more leakage than with leathers. 222. EFFICIENCY OF PUMPS AND ACCUMULATOR. E = any number of revolutions of engine. r = rise of accumulator in inches for same number of revolutions. D = diameter of accumulator. ram in inches. d = diameter of pump in inches (piston if double-acting, ram if single-acting). 8 = stroke of pump in inches. n = number of pumps. Efficiency = Loss per cent of working 1 = 100 {(tfsn'R) - (D 2 - r)} capacity of pumps . . J d 2 n R When all parts are in good order, the loss in the pumps averages 5 per cent. 223. POWER AND SPEED OF HYDRAULIC HAULING MACHINES. Strain on Hauling Speed, Hope. ft. per nrin. v ., 20001bs. 180 Railway capstans.. .. Barge .. .. 1 J tons 120 Ship .. .. 2Jto5 80 Railway traversers .. 75 Ibs. per ton of load. Lock gate machines .. J 375 * PCT f 0t [ ol entrance. LONDON: PRINTED BY WILLIAM CLOWES AND SONS, LIMITED, STAMFOKD STKEET AKD CHABING CKOSS. SPONS' DICTIONARY OF ENGINEERING, WITH TECHNICAL TEEMS IN FEENCH, GEEMAN, ITALIAN, AND SPANISH, In 97 Numbers, Super-royal 8vo, containing 3132 Printed Pages and 7414 Engravings. ANY NUMBER CAN BE HAD SEPARATE. Nos. 1 to 95, Is. each, post-free ; Nos. 96, 97, 2s. post-free. COMPLETE LIST OF ALL THE SUBJECTS. Nos. Nos. Abacus .. 1 Archimedean Screw . . .. .. 4 Adhesion .. 1 Arming Press . . 4 and 5 Agricultural Engines 1 and 2 Armour .. .. 5 Air-Chamber .. 2 Arsenic .. .. 5 Air-Pump .. 2 Artesian Well .. .. .. .. 5 Algebraic Signs .. 2 Assaying .. .. 6 Alloy 2 Artillery .. 5 and 6 Aluminium .. 2 Atomic "Weights .. 6 and 7 Amalgamating Machine . . .. 2 Augur .. 7 Ambulance .. 2 Axles . 7 Anchors .. 2 Balance .. .. 7 Anemometer 2 and 3 Ballast .. .. 7 Angular Motion 3 and 4 Bank Note Machinery .. .. 7 Angle-iron .. 3 Barn Machinery . . 7 and 8 Angle of Friction .. 3 Barker's Mill .. .. .. .. 8 Animal Charcoal Machine .. 4 Barometer .. .. 8 Antimony .. 4 Barracks .. .. 8 Anvil 4 Barrage . . 8 and 9 Aqueduct .. 4 Battery 9 and 10 Arch 4 Bell and Bell-hanging . 10 Belts and Belting Bismuth Blast Furnace . . BloAving Machine Body Plan .. .. Boilers Bond Bone Mill . Nos. 10 and 11 .. .. 11 11 and 12 .. .. 12 12 and 13 13, 14, 15 15 and 16 . 16 Boot-making Machinery . . . . 16 Boring and Blasting . . .. 16 to 19 Brake 19 and 20 Bread Machine 20 Brewing Apparatus .. 20 and 21 Brick -making Machines .. ..21 Bridges 21 to 28 Buffer 28 Cables 28 and 29 Cam 29 Canal 29 Candles 29 and 30 Cement 30 Chimney 30 Coal, Cutting and Washing Ma- chinery 31 Coast Defence .. .. 31 and 32 Compasses 32 Construction .. .. 32 and 33 Cooler 34 Copper 34 Cork- cutting Machine . . . . 34 Corrosion 34 and 35 Cotton Machinery 35 Damming 35 to 37 Details of Engines . . . . 37, 38 Displacement 38 Distilling Apparatus 38 and 39 Diving and Diving Bells . . . . 39 Docks 39 and 40 Drainage 40 and 41 Drawbridge 41 Dredging Machine 41 Dynamometer Electro-Metallurgy . . Engines, Varieties .. Engines, Agricultural Engines, Marine Engines, Screw Engines, Stationary . . Escapement Fan File-cutting Machine Fire-arms Flax Machinery Float Water-wheels .. Forging Founding and Casting Friction Friction, Angle of . . Fuel Furnace Fuze Gas Gearing Gearing Belt .. .. Geodesy Glass machinery Nos. ..41 to 43 .. 43,44 . . 44, 45 .. 1 and 2 .. 74,75 .. 89,90 .. 91,92 .. 45,46 .. .. 46 .. .. 46 .. 46,47 .. 47, 48 .. .. 48 .. .. 48 ..48 to 50 .. .. 50 .. .. 3 .. .. 50 .. 50,51 .. .. 51 .. .. 51 .. 51,52 .. 10,11 52 and 53 . 53 Gold 53,54 Governor 54 Gravity 54 Grindstone 54 Gun-carriage 54 Gun Metal 54 Gunnery 54 to 56 Gunpowder 56 Gun Machinery 56, 57 Hand Tools 57,58 Hanger 58 Harbour 58 Haulage 58,59 Hinging 59 Hydraulics and Hydraulic Ma- chinery 59 to 63 Nos. Ice-making Machine 63 India-rubber .63 Indicator 63 and 64 Injector 64 Iron 64 to 67 Iron Ship Building 67 Irrigation 67 and 68 Isomorphism 6S Joints 68 Keels and Coal Shipping 68 and 69 Kiln 69 Knitting Machine 69 Kyanising 69 Lamp, Safety 69,70 Lead 70 Lifts, Hoists 70,71 Lights, Buoys, Beacons 71 and 72 Limes, Mortars, and Cements . . 72 Locks and Lock Gates . . 72, 73 Locomotive 73 Machine Tools 73, 74 Manganese 74 Marine Engine . . . . 74 and 75 Materials of Construction 75 and 76 Measuring and Folding . . . . 76 Mechanical Movements . . 76, 77 Mercury 77 Metallurgy 77 Meter 77, 78 Metric System 78 Mills 78,79 Molecule 79 Oblique Arch 79 Ores 79,80 Nos 80 Ovens Over-shot Water-wheel Paper Machinery Permanent "Way Piles and Pile-driving Pipes Planimeter Pumps Quarrying Kailway Engineering Retaining Walls Kivers Eivetted Joint .. Koads Roofs Rope-making Machinery Scaffolding Screw Engines Signals Silver 90,91 Stationary Engine . . . . 91, 92 Stave-making and Cask Ma- chinery 92 Steel 92 Sugar Mill 92,93 Surveying and Surveying In- struments 93,94 Telegraphy 94,95 Testing 95 Turbine 95 Ventilation 95,96,97 Waterworks 96,97 Wood-working Machinery 96, 97 Zinc 90,97 .. 80, 81 .. .. 81 .. 81,82 82 and 83 .. 83, 84 .. .. 84 84 and 85 .. .. 85 85 and 86 .. .. 86 .. 86,87 .. .. 87 .. 87,88 .. 88,89 .. .. 89 ., .. 89 .. 89,90 ,. 90 The complete Work can also le lad bound in 3 Vols. cloth, price 5 5s. E. & F. N. SPON, 125, Strand. 1889. BOOKS RELATING TO APPLIED SCIENCE, PUBLISHED BY E. & F. N. SPON, LONDON: 125, STRAND. NEW YORK : 12, CORTLANDT STREET. A Pocket- Book for Chemists, Chemical Manufacturers, Metallurgists, Dyers, Distillers, Breivers, Sugar Refiners, Photographers, Students, etc., etc. By THOMAS BAYLEY, Assoc. R.C. Sc. Ireland, Ana- lytical and Consulting Chemist and Assayer. Fourth edition, with additions, 437 pp., royal 32mo, roan, gilt edges, $s. SYNOPSIS OF CONTENTS : Atomic Weights and Factors Useful Data Chemical Calculations Rules for Indirect Analysis Weights and Measures Thermometers and Barometers Chemical Physics Boiling Points, etc. Solubility of Substances Methods of Obtaining Specific Gravity Con- version of Hydrometers Strength of Solutions by Specific Gravity Analysis Gas Analysis- Water Analysis Qualitative Analysis and Reactions Volumetric Analysis Manipulation Mineralogy Assaying Alcohol Beer Sugar Miscellaneous Technological matter relating to Potash, Soda, Sulphuric Acid, Chlorine, Tar Products, Petroleum, Milk, Tallow, Photography, Prices, Wages, Appendix, etc., etc. The Mechanician : A Treatise on the Construction and Manipulation of Tools, for the use and instruction of Young Engineers and Scientific Amateurs, comprising the Arts of Blacksmithing and Forg- ing ; the Construction and Manufacture of Hand Tools, and the various Methods of Using and Grinding them ; the Construction of Machine Tools, and how to work them ; Machine Fitting and Erection ; description of Hand and Machine Processes ; Turning and Screw Cutting ; principles of Constructing and details of Making and Erecting Steam Engines, and the various details of setting out work, etc., etc. By CAMERON KNIGHT, Engineer. Containing 1147 illustrations, and 397 pages of letter-press, Fourth edition, 4to, cloth, i8j. CATALOGUE OF SCIENTIFIC BOOKS Just Published, in Demy $>vo, cloth, containing 975 pages and 250 Illustrations, price -js. 6d. SPONS' HOUSEHOLD MANUAL: A Treasury of Domestic Eeceipts and G-uide for Home Management. PRINCIPAL CONTENTS. Hints for selecting 1 a good House, pointing out the essential requirements for a good house as to the Site, Soil, Trees, Aspect, Construction, and General Arrangement ; with instructions for Reducing Echoes, Waterproofing Damp Walls, Curing Damp Cellars. Sanitation- What should constitute a good Sanitary Arrangement ; Examples (with illustrations) of Well- and Ill-drained Houses ; How to Test Drains ; Ventilating Pipes, etc. Water Supply Care of Cisterns ; Sources of Supply ; Pipes ; Pumps ; Purification and Filtration of Water. Ventilation and Warming-. 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CONTENTS : The Appointment and Duties of the Town Surveyor Traffic Macadamised Roadways Steam Rolling Road Metal and Breaking Pitched Pavements Asphalte Wood Pavements Footpaths Kerbs and Gutters Street Naming and Numbering Street Lighting hewer- age Ventilation of Sewers Disposal of Sewage House Drainage Disinfection Gas and Water Companies, etc., Breaking up Streets Improvement of Private Streets Borrowing Powers Artizans' and Labourers' Dwellings Public Conveniences Scavenging, including Street Cleansing Watering and the Removing of Snow Planting Street Trees Deposit of Plans Dangerous Buildings Hoardings Obstructions Improving Street Lines Cellar Openings Public Pleasure Grounds Cemeteries Mortuaries Cattle and Ordinary Markets Public Slaughter-houses, etc. Giving numerous Forms of Notices, Specifications, and General Information upon these and other subjects of great importance to Municipal Engi- neers and others engaged in Sanitary Work. Metrical Tables. By G. L. MOLESWORTH, M.I.C.E. 32mo, cloth, is. 6d. CONTENTS. General Linear Measures Square Measures Cubic Measures Measures of Capacity- Weights Combinations Thermometers. Elements of Construction for Electro- Magnets. By Count TH. Du MONCEL, Mem. de 1'Institut de France. Translated from the French by C. J. WHARTON. Crown 8vo, cloth, 4.5-. 6d. Practical Electrical Units Popularly Explained, with numero^ls illustrations and Remarks. By JAMES SWINBURNE, late of J. W. Swan and Co., Paris, late of Brush- Swan Electric Light Company, U.S.A. i8mo, cloth, is. 6d. A Treatise on the Use of Belting for the Transmis- sion of Power. By J. H. COOPER. Second edition, illustrated, 8vo, cloth, 15^. A Pocket-Book of Useful Formula and Memoranda for Civil and Mechanical Engineers. By GUILFORD L. MOLESWORTH, Mem. Inst. C.E., Consulting Engineer to the Government of India for State Railways. With numerous illustrations t 744 pp. Twenty-second edition, revised and enlarged, 32mo, roan, 6s. SYNOPSIS OF CONTENTS: Surveying, Levelling, etc. Strength and Weight of Materials Earthwork, Brickwork, Masonry, Arches, etc. Struts, Columns, Beams, and Trusses Flooring, Roofing, and Roof Trusses Girders, Bridges, etc. Railways and Roads Hydraulic Formulae Canals. Sewers, Waterworks, Docks Irrigation and Breakwaters Gas, Ventilation, and Warming Heat, Light, Colour, and Sound Gravity : Centres, Forces, and Powers Millwork, Teeth of Wheels, Shafting, etc. Workshop Recipes Sundry Machinery Animal Power Steam and the Steam Engine Water-power, Water-wheels, Turbines, etc. Wind and Windmills- Steam Navigation, Ship Building, Tonnage, etc. Gunnery, Projectiles, etc. Weights, Measures, and Money Trigonometry, Conic Sections, and Curves Telegraphy Mensura- tion Tables of Areas and Circumference, and Arcs of Circles Logarithms, Square and Cube Roots, Powers Reciprocals, etc. Useful Numbers Differential and Integral Calcu- lus Algebraic Signs Telegraphic Construction and Formulae. CATALOGUE OF SCIENTIFIC BOOKS Hints on Architectural Draughtsmanship. By G. W. TUXFORD HALLATT. Fcap. 8vo, cloth, is. 6d. Spans Tables and Memoranda for Engineers; selected and arranged by J. T. HURST, C.E., Author of 'Architectural Surveyors' Handbook,' ' Hurst's Tredgold's Carpentry,' etc. Ninth edition, 64010, roan, gilt edges, I s. ; or in cloth case, is. 6d. This work is printed in a pearl type, and is so small, measuring only 2^ in. by i| in. by i in. thick, that it may be easily carried in the waistcoat pocket. " It is certainly an extremely rare thing for a reviewer to be called upon to notice a volume measuring but 23 in. by if in., yet these dimensions faithfully represent the size of the handy little book before us. The volume which contains 118 printed pages, besides a few blank pages for memoranda is, in fact, a true pocket-book, adapted for being carried in the waist- coat pocket, and containing a far greater amount and variety of information than most people would imagine could be compressed into so small a space. The little volume has been compiled with considerable care and judgment, and we can cordially recommend it to our readers as a useful little pocket companion." Engineering. A Practical Treatise on Natural and Artificial Concrete, its Varieties and Constructive Adaptations. By HENRY REID, Author of the ' Science and Art of the Manufacture of Portland Cement.' New Edition, with 59 -woodcuts and 5 plates, 8vo, cloth, 15^. Notes on Concrete and Works in Concrete; especially written to assist those engaged upon Public Works. By JOHN NEWMAN, Assoc. Mem. Inst. C.E., crown 8vo, cloth, 4^. 6d. Electricity as a Motive Power. By Count TH. Du MONCEL, Membre de PInstitut de France, and FRANK GERALDY, Inge- nieur des Fonts et Chaussees. Translated and Edited, with Additions, by C. J. WHARTON, Assoc. Soc. Tel. Eng. and Elec. With 113 engravings and diagrams, crown 8vo, cloth, Js. 6d. Treatise on Valve-Gears, with special consideration of the Link-Motions of Locomotive Engines. By Dr. GUSTAV ZEUNER, Professor of Applied Mechanics at the Confederated Polytechnikum of Zurich. Translated from the Fourth German Edition, by Professor J. F. KLEIN, Lehigh University, Bethlehem, Pa. Illustrated, 8vo, cloth, I2s. 6d. The French - Polishers Manual. By a French- Polisher; containing Timber Staining, Washing, Matching, Improving, Painting, Imitations, Directions for Staining, Sizing, Embodying, Smoothing, Spirit Varnishing, French-Polishing, Directions for Re- polishing. Third edition, royal 32mo, sewed, 6d. Hops, their Cultivation, Commerce, and Uses in various Countries. By P. L. SIMMONDS. Crown 8vo, cloth, 4^. 6d. The Principles of Graphic Statics. By GEORGE SYDENHAM CLARKE, Capt. Royal Engineers. With 112 illustrations* 4to, cloth, I2s. 6d. PUBLISHED BY E. & F. N. SPON. Dynamo-Electric Machinery : A Manual for Students of Electro-technics. By SILVANUS P. THOMPSON, B.A., D.Sc., Professor of Experimental Physics in University College, Bristol, etc., etc. Third edition, illustrated, 8vo, cloth, i6s. Practical Geometry, Perspective, and Engineering Drawing', a Course of Descriptive Geometry adapted to the Require- ments of the Engineering Draughtsman, including the determination of cast shadows and Isometric Projection, each chapter being followed by numerous examples ; to which are added rules for Shading, Shade-lining, etc., together with practical instructions as to the Lining, Colouring, Printing, and general treatment of Engineering Drawings, with a chapter on drawing Instruments. By GEORGE S. CLARKE, Capt. R.E. Second edition, with 21 plates. 2 vols., cloth, IO.T. 6d. The Elements of Graphic Statics. By Professor KARL VON OTT, translated from the German by G. S. CLARKE, Capt. R.E., Instructor in Mechanical Drawing, Royal Indian Engineering College. With 93 illustrations, crown 8vo, cloth, $s. A Practical Treatise on the Manufacture and Distri- bution of Coal Gas. By WILLIAM RICHARDS. Demy 410, with numerous wood engravings and 29 plates, cloth, 2%s. SYNOPSIS OF CONTENTS : Introduction History of Gas Lighting Chemistry of Gas Manufacture, by Lewis Thompson, Esq., M.R.C.S. Coal, with Analyses, by J. Paterson, Lewis Thompson, and G. R. Hislop, Esqrs. Retorts, Iron and Clay Retort Setting Hydraulic Main Con- densers Exhausters Washers and Scrubbers Purifiers Purification History of Gas Holder Tanks, Brick and Stone, Composite, Concrete, Cast-iron, Compound Annular Wrpught-iron Specifications Gas Holders Station Meter Governor Distribution Mains Gas Mathematics, or Formulae for the Distribution of Gas, by Lewis Thompson, Esq. Services Consumers' Meters Regulators Burners Fittings Photometer Carburization of Gas Air Gas and Water Gas Composition of Coal Gas, by Lewis Thompson, Esq. Analyses of Gas Influence of Atmospheric Pressure and Temperature on Gas Residual Products Appendix Description of Retort Settings, Buildings, etc., etc. The New Formula for Mean Velocity of Discharge of Rivers and Canals. By W. R. KUTTER. Translated from articles in the 'Cultur-Ingenieur,' by Lowis D'A. JACKSON, Assoc. Inst. C.E. 8vo, cloth, I2J. 6d. The Practical Millwright and Engineers Ready Reckoner; or Tables for finding the diameter and power of cog-wheels, diameter, weight, and power of shafts, diameter and strength of bolts, etc. By THOMAS DIXON. Fourth edition, I2mo, cloth, 3-r. Tin: Describing the Chief Methods of Mining, Dressing and Smelting it abroad ; with Notes upon Arsenic, Bismuth and Wolfram. By ARTHUR G. CHARLETON, Mem. American Inst. of Mining Engineers. With plates ', 8vo, cloth, 12s. 6a\ B 3 io CATALOGUE OF SCIENTIFIC BOOKS Perspective, Explained and Ilhistrated. By G. S. CLARKE, Capt. R.E. With illustrations, 8vo, cloth, 3^. 6d. Practical Hydraulics ; a Series of Rules and Tables for the use of Engineers, etc., etc. By THOMAS Box. Fifth edition, numerous plates, post 8vo, cloth, 5-r. The Essential Elements of Practical Mechanics; based on the Principle of Work, designed for Engineering Students. By OLIVER BYRNE, formerly Professor of Mathematics, College for Civil Engineers. Third edition, with 148 wood engravings, post 8vo, cloth, 7j. 6d. CONTENTS : Chap. I. How Work is Measured by a Unit, both with and without reference to a Unit of Time Chap. 2. The Work of Living Agents, the Influence of Friction, and introduces one of the most beautiful Laws of Motion Chap. 3. The principles expounded in the first and second chapters are applied to the Motion of Bodies Chap. 4. The Transmission of Work by simple Machines Chap. 5. Useful Propositions and Rules. Breweries and Mailings : their Arrangement, Con- struction, Machinery, and Plant. By G. SCAMELL, F.R.I.B.A. Second edition, revised, enlarged, and partly rewritten. By F. COLYER, M.I.C.E., M.I.M.E. With 20 plates, 8vo, cloth, i8.r. A Practical Treatise on the Construction of Hori- zontal and Vertical Waterivheels, specially designed for the use of opera- tive mechanics. By WILLIAM CULLEN, Millwright and Engineer. With II plates. Second edition, revised and enlarged, small 4to, cloth, I2s. 6d. A Practical Treatise on Mill-gearing, Wheels, Shafts, Riggers, etc. ; for the use of Engineers. By THOMAS Box. Third edition, with II plates. Crown 8vo, cloth, *]s. 6d. Mining Machinery: a Descriptive Treatise on the Machinery, Tools, and other Appliances used in Mining. By G. G. ANDRE, F.G.S., Assoc. Inst. C.E., Mem. of the Society of Engineers. Royal 4to, uniform with the Author's Treatise on Coal Mining, con- taining 182 plates, accurately drawn to scale, with descriptive text, in 2 vols., cloth, 3/. I2s. CONTENTS : Machinery for Prospecting, Excavating, Hauling, and Hoisting Ventilation Pumping Treatment of Mineral Products, including Gold and Silver, Copper, Tin, and Lead, Iron Coal, Sulphur, China Clay, Brick Earth, etc. Tables for Setting out Curves for Railways, Canals, Roads, etc., varying from a radius of five chains to three miles. By A. KENNEDY and R. W. HACKWOOD. Illustrated, 32mo, cloth, 2s. 6d. PUBLISHED BY E. & F. N. SPON. n The Science and Art of the Manufacture of Portland Cement, with observations on some of its constructive applications. With 66 illustrations. By HENRY REID, C.E., Author of 'A Practical Treatise on Concrete,' etc., etc. 8vo, cloth, iSs. The Draughtsman s Handbook of Plan and Map Drawing; including instructions for the preparation of Engineering, Architectural, and Mechanical Drawings. With numerous illustrations in the text, and 33 plates (15 printed in colours}. By G. G. ANDRE, F.G.S., Assoc. Inst. C.E. 4to, cloth, 9.?. CONTENTS : The Drawing Office and its Furnishings Geometrical Problems Lines, Dots, and their Combinations Colours, Shading, Lettering, Bordering, and North Points Scales Plotting Civil Engineers' and Surveyors' Plans Map Drawing Mechanical and Architectural Drawing Copying and Reducing Trigonometrical Formulae, etc., etc. The B oiler-maker s andiron Ship-builder s Companion, comprising a series of original and carefully calculated tables, of the utmost utility to persons interested in the iron trades. By JAMES FODEN, author of ' Mechanical Tables,' etc. Second edition revised, with illustra- tions, crown 8vo, cloth, $s. Rock Blasting: a Practical Treatise on the means employed in Blasting Rocks for Industrial Purposes. By G. G. ANDRE, F.G.S., Assoc. Inst. C.E. With 56 illustrations and 12 plates, 8vo, cloth, Painting and Painters Manual: a Book of Facts for Painters and those who Use or Deal in Paint Materials. By C. L. CONDIT and J. SCHELLER. Illustrated, 8vo, cloth, los. 6d. A Treatise on Ropemaking as practised in public and private Rope-yards, with a Description of the Manufacture, Rules, Tables of Weights, etc., adapted to the Trade, Shipping, Mining, Railways, Builders, etc. By R. CHAPMAN, formerly foreman to Messrs. Huddart and Co., Limehouse, and late Master Ropemaker to H.M. Dockyard, Deptford. Second edition, I2mo, cloth, 3-r. Laxton s Builders and Contractors Tables ; for the use of Engineers, Architects, Surveyors, Builders, Land Agents, and others. Bricklayer, containing 22 tables, with nearly 30,000 calculations. 4to, cloth, 5-r. Laxtons Builders and Contractors Tables. Ex- cavator, Earth, Land, Water, and Gas, containing 53 tables, with nearly 24,000 calculations. 4to, cloth, $s 12 CATALOGUE OF SCIENTIFIC BOOKS Sanitary Engineering: a Guide to the Construction of Works of Sewerage and House Drainage, with Tables for facilitating the calculations of the Engineer. By BALDWIN LATHAM, C.E., M. Inst. C.E., F.G.S., F.M.S., Past-President of the Society of Engineers. Second edition, -with numerous plates and woodcuts ', 8vo, cloth, I/, icxr. Screw Cutting Tables for Engineers and Machinists, fiving the values of the different trains of Wheels required to produce crews of any pitch, calculated by Lord Lindsay, M.P., F.R.S., F.R.A.S., etc. Cloth, oblong, 2s. Screw Cutting Tables, for the use of Mechanical Engineers, showing the proper arrangement of Wheels for cutting the Threads of Screws of any required pitch, with a Table for making the Universal Gas-pipe Threads and Taps. By W. A. MARTIN, Engineer. Second edition, oblong, cloth, u., or sewed, 6d. A Treatise on a Practical Method of Designing Slide- Valve Gears by Simple Geometrical Constrtiction, based upon the principles enunciated in Euclid's Elements, and comprising the various forms of Plain Slide- Valve and Expansion Gearing ; together with Stephenson's, Gooch's, and Allan's Link-Motions, as applied either to reversing or to variable expansion combinations. By EDWARD J. COWLING WELCH, Memb. Inst. Mechanical Engineers. Crown 8vo, cloth, 6s. Cleaning and Scouring : a Manual for Dyers, Laun- dresses, and for Domestic Use. By S. CHRISTOPHER. i8mo, sewed, 6d. A Glossary of Terms used in Coal Mining. By WILLIAM STUKELEY GRESLEY, Assoc. Mem. Inst. C.E., F.G.S., Member of the North of England Institute of Mining Engineers. Illustrated with numerous woodcuts and diagrams, crown 8vo, cloth, 5^. A Pocket-Book for Boiler Makers and Steam Users, comprising a variety of useful information for Employer and Workman, Government Inspectors, Board of Trade Surveyors, Engineers in charge of Works and Slips, Foremen of Manufactories, and the general Steam- using Public. By MAURICE JOHN SEXTON. Second edition, royal 32mo, roan, gilt edges, 5-r. Electrolysis: a Practical Treatise on Nickeling, Coppering, Gilding, Silvering, the Refining of Metals, and the treatment of Ores by means of Electricity. By HIPPOLYTE FONTAINE, translated from the French by J. A. BERLY, C.E., Assoc. S.T.E. With engravings. Svo, cloth, gs. PUBLISHED BY E. & F. N. SPON. 13 Barlow s Tables of Squares, Cubes, Square Roots, Cube Roots, Reciprocals of all Integer Numbers up to 10,000. Post 8vo, cloth, 6s. A Practical Treatise on the Steam Engine, con- taining Plans and Arrangements of Details for Fixed Steam Engines, with Essays on the Principles involved in Design and Construction. By ARTHUR RIGG, Engineer, Member of the Society of Engineers and of the Royal Institution of Great Britain. Demy 4to, copiously illustrated with woodcuts and 96 plates, in one Volume, half-bound morocco, 2l. 2s. ; or cheaper edition, cloth, 2$s. This work is not, in any sense, an elementary treatise, or history of the steam engine, but is intended to describe examples of Fixed Steam Engines without entering into the wide domain of locomotive or marine practice. To this end illustrations will be given of the most recent arrangements of Horizontal, Vertical, Beam, Pumping, Winding, Portable, Semi- portable, Corliss, Allen, Compound, and other similar Engines, by the most eminent Firms in Great Britain and America. The laws relating to the action and precautions to be observed in the construction of the various details, such as Cylinders, Pistons, Piston-rods, Connecting- rods, Cross-heads, Motion-blocks, Eccentrics, Simple, Expansion, Balanced, and Equilibrium Slide-valves, and Valve-gearing will be minutely dealt with. In this connection will be found articles upon the Velocity of Reciprocating Parts and the Mode of Applying the Indicator, Heat and Expansion of Steam Governors, and the like. It is the writer's desire to draw illustrations from every possible source, and give only those rules that present practice deems correct. A Practical Treatise on the Science of Land and Engineering Surveying, Levelling, Estimating Quantities, etc., with a general description of the several Instruments required for Surveying, Levelling, Plotting, etc. By H. S. MERRETT. Fourth edition, revised by G. W. USILL, Assoc. Mem. Inst. C.E. 41 plates, with illustrations and tables, royal 8vo, cloth, I2s. 6d. PRINCIPAL CONTENTS : Part i. Introduction and the Principles of Geometry. Part 2. Land Surveying; com- _ veymg- _ _ Laying out of Land Observations on Enclosures Plane Trigonometry. Part 3. Levelling Simple and Compound Levelling The Level Book Parliamentary Plan and Section- Levelling with a Theodolite Gradients Wooden Curves To Lay out a Railway Curve- Setting out Widths. Part 4. Calculating Quantities generally for Estimates Cuttings and Embankments Tunnels Brickwork Ironwork Timber Measuring. Part 5. Description and Use of Instruments in Surveying and Plotting The Improved Dumpy Level Troughton's Level The Prismatic Compass Proportional Compass Box Sextant Vernier Panta- graph Merrett's Improved Quadrant Improved Computation Scale The Diagonal Scale -Straight Edge and Sector. Part 6. Logarithms of Numbers Logarithmic Sines and Co-Sines, Tangents and Co-TangentsNatural Sines and Co-SinesTables for Earthwork, for Setting out Curves, and for various Calculations, etc., etc., etc. Health and Comfort in House Building, or Ventila- tion with Warm Air by Self- Acting Suction Power, with Review of the mode of Calculating the Draught in Hot- Air Flues, and with some actual Experiments. By J. DRYSDALE, M.D., and J. W. HAYWARD, M.D. Second edition, with Supplement, with plates, demy 8vo, cloth, "Js. 6d. CATALOGUE OF SCIENTIFIC BOOKS. The Assayers Manual: an Abridged Treatise on the Docimastic Examination of Ores and Furnace and other Artificial Products. By BRUNO KERL. Translated by W. T. BRANNT. With 65 UlustrafaH3 % 8vo, cloth, I2s. 6d. Electricity: its Theory, Sources, and Applications. By J. T. SPRAGUE, M.S.T.E. Second edition, revised and enlarged, with numerous illustrations, crown 8vo, cloth, i$s. The Practice of Hand Turning in Wood, Ivory, Shell, etc., with Instructions for Turning such Work in Metal as may be required in the Practice of Turning in Wood, Ivory, etc. ; also an Appendix on Ornamental Turning. (A book for beginners.) By FRANCIS CAMPIN. Third edition, with wood engravings, crown 8vo, cloth, 6s. CONTENTS : On Lathes Turning Tools Turning Wood Drilling Screw Cutting Miscellaneous Apparatus and Processes Turning Particular Forms Staining Polishing Spinning Metals Materials Ornamental Turning, etc. Treatise on Watchwork, Past and Present. By the Rev. H. L. NELTHROPP, M.A., F.S.A. With 32 illustrations, crown 8vo, cloth, 6s. 6d. CONTENTS : Definitions of Words and Terms used in Watchwork Tools Time Historical Sum- mary On Calculations of the Numbers for Wheels and Pinions; their Proportional Sizes, Trains, etc. Of Dial Wheels, or Motion Work Length of Time of Going without Winding up The Verge The Horizontal The Duplex The Lever The Chronometer Repeating Watches Keyless Watches The Pendulum, or Spiral Spring Compensation Jewelling of Pivot Holes Clerkenwell Fallacies of the Trade Incapacity of Workmen How to Choose and Use a Watch, etc. Algebra Self-Taught. By W. P. HIGGS, M.A., D.Sc., LL.D., Assoc. Inst C.E., Author of ' A Handbook of the Differ- ential Calculus,' etc. Second edition, crown 8vo, cloth, zs. 6d. CONTENTS : Symbols and the Signs of Operation The Equation and the Unknown Quantity Positive and Negative Quantities Multiplication Involution Exponents Negative Expo- nents Roots, and the Use of Exponents as Logarithms Logarithms Tables of Logarithms and Proportionate Parts Transformation of System of Logarithms Common Uses of Common Logarithms Compound Multiplication and the Binomial Theorem Division, Fractions, and Ratio Continued Proportion The Series and the Summation of the Series Limit of Series Square and Cube Roots Equations List of Formulae, etc. Spans 9 Dictionary of Engineering, Civil, Mechanical, Military, and Naval; with technical terms in French, German, Italian, and Spanish, 3100 pp., and nearly 8000 engravings, in super-royal 8vo, in 8 divisions, 5/. 8-r. Complete in 3 vols., cloth, 5/. $s. Bound in a superior manner, half-morocco, top edge gilt, 3 vols., 67. I2J. PUBLISHED BY E. & F. N. SPON. 15 Notes in Mechanical Engineering. Compiled prin- cipally for the use of the Students attending the Classes on this subject at the City of London College. By HENRY ADAMS, Mem. Inst. M.E., Mem. Inst. C.E., Mem. Soc. of Engineers. Crown 8vo, cloth, 2*. 6d. Canoe and Boat Building: a complete Manual for Amateurs, containing plain and comprehensive directions for the con- struction of Canoes, Rowing and Sailing Boats, and Hunting Craft. By W. P. STEPHENS. With numerous illustrations and 24 plates oj Working Drawings. Crown 8vo, cloth, Js. 6d. Proceedings of the National Conference of Electricians, Philadelphia, October 8th to I3th, 1884. i8mo, cloth, ^s. Dynamo - Electricity, its Generation, Application, Transmission, Storage, and Measurement. By G. B. PRESCOTT. With 545 illustrations. 8vo, cloth, I/, u. Domestic Electricity for Amateurs. Translated from the French of E. HOSPITALIER, Editor of " L'Electricien," by C. J. WHARTON, Assoc. Soc. Tel. Eng. Numerous illustrations. Demy 8vo, cloth, gs. CONTENTS: i. Production of the Electric Current 2. Electric Bells 3. Automatic Alarms 4. Domestic Telephones 5. Electric Clocks 6. Electric Lighters 7. Domestic Electric Lighting 8. Domestic Application of the Electric Light 9. Electric Motors 10. Electrical Locomo- tion ii. Electrotyping, Plating, and Gilding 12. Electric Recreations 13. Various appli- cations Workshop of the Electrician. Wrinkles in Electric Lighting. By VINCENT STEPHEN. With illustrations. i8mo, cloth, 2s. 6d. CONTENTS: i. The Electric Current and its production by Chemical means 2. Production of Electric Currents by Mechanical means 3. Dynamo-Electric Machines 4. Electric Lamps 5. Lead 6. Ship Lighting. The Practical Flax Spinner ; being a Description of the Growth, Manipulation, and Spinning of Flax and Tow. By LESLIE C. MARSHALL, of Belfast. With illustrations. 8vo, cloth, 15^. Foundations and Foundation Walls for all classes of Buildings, Pile Driving, Building Stones and Bricks, Pier and Wall construction, Mortars, Limes, Cements, Concretes, Stuccos, &c. 64 illus~ trations. By G. T. POWELL and F. BAUMAN. 8vo, cloth, IQJ. 6< 1 6 CATALOGUE OF SCIENTIFIC BOOKS Manual for Gas Engineering Students. By D. LEE. i8mo, cloth is. Hydraulic Machinery, Past and Present. A Lecture delivered to the London and Suburban Railway Officials' Association. By H. ADAMS, Mem. Inst. C.E. Folding plate. 8vo, sewed, i j. Twenty Years with the Indicator. By THOMAS PRAY, Jun., C.E., M.E., Member of the American Society of Civil Engineers. 2 vols., royal 8vo, cloth, I2s. 6d. Annual Statistical Report of the Secretary to the Members of the Iron and Steel Association on the Home and Foreign Iron and Steel Industries in 1884. Issued March 1885. 8vo, sewed, $s. Bad Drains, and How to Test them ; with Notes on the Ventilation of Sewers, Drains, and Sanitary Fittings, and the Origin and Transmission of Zymotic Disease. By R. HARRIS REEVES. Crown 8vo, cloth, 3J. 6d. Well Sinking. The modern practice of Sinking and Boring Wells, with geological considerations and examples of Wells. By ERNEST SPON, Assoc. Mem. Inst. C.E., Mem. Soc. Eng., and of the Franklin Inst., etc. Second edition, revised and enlarged. Crown 8vo, cloth, lew. 6d. Pneumatic Transmission of Messages and Parcels between Paris and London, via Calais and Dover. By J. B. BERLIER, C.E. Small folio, sewed, 6d. List of Tests (Reagents), arranged in alphabetical order, according to the names of the originators. Designed especially for the convenient reference of Chemists, Pharmacists, and Scientists. By HANS M. WILDER. Crown 8vo, cloth, 4?. 6d. Ten Years Experience in Works of Intermittent Downward Filtration. By J. BAILEY DENTON, Mem. Inst. C.E. Second edition, with additions. Royal 8vo, sewed, 4^. A Treatise on the Manufacture of Soap and Candles, Lubricants and Glycerin. By W. LANT CARPENTER, B.A., B.Sc. (late of Messrs. C. Thomas and Brothers, Bristol). With illustrations, Crovui 8vo, cloth, \Qs. 6tt. PUBLISHED BY E. & F. N. SPON. i? The Stability of Ships explained simply, and calculated by a new Graphic method. By J. C. SPENCE, M.I.N.A. 4to, sewed, Steam Making, or Boiler Practice. By CHARLES A. SMITH, C.E. 8vo, cloth, IQJ-. 6d. CONTENTS : i. The Nature of Heat and the Properties of Steam 2. Combustion. 3. Externally Fired Stationary Boilers 4. Internally Fired Stationary Boilers 5. Internally Fired Portable Locomotive and Marine Boilers 6. Design, Construction, and Strength of Boilers 7. Pro- portions of Heating Surface, Economic Evaporation, Explosions 8. Miscellaneous Boilers, Choice of Boiler Fittings and Appurtenances. The Fireman s Guide ; a Handbook on the Care of Boilers. By TEKNOLOG, foreningen T. I. Stockholm. Translated from the third edition, and revised by KARL P. DAHLSTROM, M.E. Second edition. Fcap. 8vo, cloth, 2s. A Treatise on Modern Steam Engines and Boilers, including Land Locomotive, and Marine Engines and Boilers, for the use of Students. By FREDERICK COLYER, M. Inst. C.E., Mem. Inst. M.E. With if* plates. 410, cloth, 25^. CONTENTS : i. Introduction 2. Original Engines 3. Boilers 4. High-Pressure Beam Engines 5. Cornish Beam Engines 6. Horizontal Engines 7. Oscillating Fngines 8. Vertical High- Pressure Engines 9. Special Engines 10. Portable Engines n. Locomotive Engines 12. Marine Engines. Steam Engine Management; a Treatise on the Working and Management of Steam Boilers. By F. COLYER, M. Inst. C.E., Mem. Inst. M.E. i8mo, cloth, 2s. Land Surveying on the Meridian and Perpendicular System. By "WILLIAM PENMAN, C.E. 8vo, cloth, Ss. 6d. The Topographer, his Instruments and Methods, designed for the use of Students, Amateur Photographers, Surveyors, Engineers, and all persons interested in the location and construction of works based upon Topography. Illustrated -with numerotis plates, maps, and engravings. By LEWIS M. HAUPT, A.M. 8vo, cloth, i&r. A Text-Book of Tanning, embracing the Preparation of all kinds of Leather. By HARRY R. PROCTOR, F.C.S., of Low Lights Tanneries. With, illustrations. Crown 8vo, cloth, IOT. 6d. In super-royal 8vo, 1168 pp., with 2400 illustrations, in 3 Divisions, cloth, price 13*. 6d. each ; or i vol., cloth, z/. ; or half-morocco, 2/. 8s. A SUPPLEMENT TO SPONS' DICTIONARY OF ENGINEERING. EDITED BY ERNEST SPON, MEMB. Soc. ENGINEERS. Abacus, Counters, Speed Indicatoi-s, and Slide Rule. Agricultural Implements and Machinery. Air Compressors. Animal Charcoal Ma- chinery. Antimony. Axles and Axle-boxes. Barn Machinery. Belts and Belting. Blasting. Boilers. Brakes. Brick Machinery. Bridges. Cages for Mines. Calculus, Differential and Integral. Canals. Carpentry. Cast Iron. Cement, Concrete, Limes, and Mortar. Chimney Shafts. Coal Cleansing and Washing. | Coal Mining. Coal Cutting Machines. Coke Ovens. Copper. Docks. Drainage. Dredging Machinery. Dynamo - Electric and Magneto-Electric Ma- chines. Dynamometers. Electrical Engineering, Telegraphy, Electric Lighting and its prac- ticaldetails,Telephones Engines, Varieties of. Explosives. Fans. Founding, Moulding and the practical work of the Foundry. Gas, Manufacture of. Hammers, Steam and other Power. Heat. Horse Power. Hydraulics. Hydro-geology. Indicators. Iron. Lifts, Hoists, and Eleva- tors. Lighthouses, Buoys, and Beacons. Machine Tools. Materials of Construc- tion. Meters. Ores, Machinery and Processes employed to- Dress. Piers. Pile Driving. Pneumatic Transmis- sion. Pumps. Pyrometers. Road Locomotives. Rock Drills. Rolling Stock. Sanitary Engineering. Shafting. Steel. Steam Navvy. Stone Machinery. Tramways. Well Sinking London: E. & F. N. SPON, 125, Strand. New York : 12, Cortlandt Street. NOW COMPLETE. With nearly 1500 illustrations, in super-royal 8vo, in 5 Divisions, cloth. Divisions I to 4, 13^. 6d. each ; Division 5, 17^. 6d. ; or 2 vols., cloth, $ IOJ. SPONS' ENCYCLOPEDIA OF THB INDUSTRIAL ARTS, MANUFACTURES, AND COMMERCIAL PRODUCTS, EDITED BY C. G. WARNFORD LOCK, F.L.S. Among the more important of the subjects treated of, are the following : Acids, 207 pp. 220 figs. Fur, 5 pp. Photography, 13 pp. 20 Alcohol, 23 pp. 1 6 figs. Gas, Coal, 8 pp. figs. Alcoholic Liquors, 13 pp. Alkalies, 89 pp. 78 figs. Gems. Glass, 45 pp. 77 figs. Pigments, 9 pp. 6 figs. Pottery, 46 pp. 57 figs. Alloys. Alum. Graphite, 7 pp. Printing and Engraving, Asphalt. Assaying. Hair, 7 pp. 20 pp. 8 figs. Beverages, 89 pp. 29 figs. Hair Manufactures. Rags. Blacks. Hats, 26 pp. 26 figs. Resinous and Gummy Bleaching Powder, 1 5 pp. Honey. Hops. Substances, 75 pp. 16 Bleaching, 5 1 pp. 48 figs. Horn. figs. Candles, 18 pp. 9 figs. Ice, 10 pp. 14 figs. Rope, 1 6 pp. 17 figs. Carbon Bisulphide. Indiarubber Manufac- Salt, 31 pp. 23 figs. Celluloid, 9 pp. tures, 23 pp. 17 figs. Silk, 8 pp. Cements. Clay. Ink, 17 pp. Silk Manufactures, 9 pp. Coal-tar Products, 44 pp. Ivory. II figs. 14 figs. Jute Manufactures, 1 1 Skins, 5 pp. Cocoa, 8 pp. pp., n figs. Small Wares, 4 pp. Coffee, 32 pp. 13 figs. Knitted Fabrics Soap and Glycerine, 39 Cork, 8 pp. 17 figs. Hosiery, 15 pp. 13 figs. pp. 45 figs. Cotton Manufactures, 62 Lace, 13 pp. 9 figs. Spices, 1 6 pp. pp. 57 figs. Leather, 28 pp. 31 figs. Sponge, 5 pp. Drugs, 38 pp. Linen Manufactures, 16 Starch, 9 pp. 10 figs. Dyeing and Calico pp. 6 figs. Sugar, 155 pp. 134 Printing, 28 pp. 9 figs. Manures, 21 pp. 30 figs. figs- Dyestuffs, 16 pp. Matches, 17 pp. 38 figs. Sulphur. Electro-Metallurgy, 13 Mordants, 13 pp. Tannin, 18 pp. pp. Narcotics, 47 pp. Tea, 12 pp. Explosives, 22 pp. 33 figs. Nuts, 10 pp. Timber, 13 pp. Feathers. Oils and Fatty Sub- Varnish, 15 pp. Fibrous Substances, 92 stances, 125 pp. Vinegar, 5 pp. pp. 79 figs. Paint. Wax, 5 pp. Floor-cloth, 1 6 pp. 21 Paper, 26 pp. 23 figs. Wool, 2 pp. figs. Paraffin, 8 pp. 6 figs. Woollen Manufactures, Food Preservation, 8 pp. Pearl and Coral, 8 pp. 58 pp. 39 figs. Fruit, 8 pp. Perfumes, 10 pp. London : E. & F. N. SPON, 135, Strand. New York : 12, Cortlantit Street. Crown 8vo, cloth, with illustrations, 5-r. WORKSHOP RECEIPTS, FIRST SERIES. BY ERNEST SPON. SYNOPSIS OF CONTENTS. Freezing. Fulminates. Furniture Creams, Oils, Polishes, Lacquers, and Pastes. Gilding. Glass Cutting, Cleaning, : Frosting, Drilling, Darkening, Bending, Staining, and Paint- ing. Glass Making. Glues. Gold. Graining. Gums. Gun Cotton. Gunpowder. Horn Working. Indiarubber. Japans, Japanning, and kindred processes. Lacquers. Lathing. Lubricants. Marble Working. Matches. Mortars. Nitre-Glycerine. Oils. Bookbinding. Bronzes and Bronzing. Candles. Cement. Cleaning. Colourwashing. Concretes. Dipping Acids. Drawing Office Details. Drying Oils. Dynamite. Electro - Metallurgy (Cleaning, Dipping, Scratch-brushing, Bat- teries, Baths, and Deposits of every description). Enamels. Engraving on Wood, Copper, Gold, Silver, Steel, and Stone. Etching and Aqua Tint. Firework Making (Rockets, Stars, Rains, Gerbes, Jets, Tour- billons, Candles, Fires, Lances,Lights, Wheels, Fire-balloons, and minor Fireworks). Fluxes. Foundry Mixtures. Besides Receipts relating to the lesser Technological matters and processes, such as the manufacture and use of Stencil Plates, Blacking, Crayons, Paste, Putty, Wax, Size, Alloys, Catgut, Tunbridge Ware, Picture Frame and Architectural Mouldings, Compos, Cameos, and others too numerous to mention. Paper. Paper Hanging. Painting in Oils, in Water Colours, as well as Fresco, House, Trans- parency, Sign, and Carriage Painting. Photography. Plastering. Polishes. Pottery (Clays, Bodies, Glazes, Colours, Oils, Stains, Fluxes, Ena- mels, and Lustres). Scouring. Silvering. Soap. Solders. Tanning. Taxidermy. Tempering Metals. Treating Horn, Mother- o'-Pearl, and like sub- stances. Varnishes, Manufacture and Use of. Veneering. Washing. Waterproofing. Welding. London: E. & F. N. SPON, 125, Strand. New York: 12, Cortlandt Street. Crown 8vo, cloth, 485 pages, with illustrations, 5j. WORKSHOP RECEIPTS, SECOND SERIES. BY ROBERT HALDANE. SYNOPSIS OF CONTENTS. Acidimetry and Alkali- Disinfectants. Isinglass. metiy. Dyeing, Staining, and Ivory substitutes. Albumen. Colouring:. Leather. Alcohol . Essences. Luminous bodies. Alkaloids. Extracts. Magnesia. Baking-powders. Fireproofing. Matches. Bitters. Gelatine, Glue, and Size. Paper. Bleaching. Glycerine. Parchment. Boiler Incrustations. Gut. Perchloric acid. Cements and Lutes. Hydrogen peroxide. Potassium oxalate. Cleansing. Ink. Preserving. Confectionery. Iodine. Copying. ' lodoform. Pigments, Paint, and Painting : embracing the preparation of Pigments, including alumina lakes, blacks (animal, bone, Frankfort, ivory, lamp, sight, soot), blues (antimony, Antwerp, cobalt, caeruleum, Egyptian, manganate, Paris, Peligot, Prussian, smalt, ultramarine), browns (bistre, hinau, sepia, sienna, umber, Vandyke), greens (baryta, Brighton, Brunswick, chrome, cobalt, Douglas, emerald, manganese, mitis, mountain, Prussian, sap, Scheele's, Schweinfurth, titanium, verdigris, zinc), reds (Brazilwood lake, carminated lake, carmine, Cassius purple, cobalt pink, cochineal lake, colco- thar, Indian red, madder lake, red chalk, red lead, vermilion), whites (alum, baryta, Chinese, lead sulphate, white lead by American, Dutch, French, German, Kremnitz, and Pattinson processes, precautions in making, and composition of commercial samples whiting, Wilkinson's white, zinc white), yellows (chrome, gamboge, Naples, orpiment, realgar, yellow lakes) ; Paint (vehicles, testing oils, driers, grinding, storing, applying, priming, drying, filling, coats, brushes, surface, water-colours, removing smell, discoloration ; miscellaneous paints cement paint for carton-pierre, copper paint, gold paint, iron paint, lime paints, silicated paints, steatite paint, transparent paints, tungsten paints, window paint, zinc paints) ; Painting (general instructions, proportions of ingredients, measuring paint work ; carriage painting priming paint, best putty, finishing colour, cause of cracking, mixing the paints, oils, driers, and colours, varnishing, importance of washing vehicles, re-varnishing, how to dry paint ; woodwork painting). London : E. & F. N. SPON, 125, Strand. New York: 12, Cortlandt Street. JUST PUBLISHED. In demy 8vo, cloth, 600 pages, and 1420 Illustrations. 6s. SPONS' MECHANICS' OWN BOOK; A MANUAL FOR HANDICRAFTSMEN AND AMATEURS. CONTENTS. Mechanical Drawing Casting and Founding in Iron, Brass, Bronze, and other Alloys Forging and Finishing Iron Sheetmetal Working Soldering, Brazing, and Burning Carpentry and Joinery, embracing descriptions of some 400 Woods, over 200 Illustrations of Tools and^ their uses, Explanations (with Diagrams) of 116 joints and hinges, and Details of Construction of Workshop appliances, rough furniture, Garden and Yard Erections, and House Building Cabinet-Making and Veneering Carving and Fretcutting Upholstery Painting, Graining, and Marbling Staining Furniture, Woods, Floors, and Fittings Gilding, dead and bright, on various grounds Polishing Marble, Metals, and Wood Varnishing Mechanical movements, illustrating contrivances for transmitting motion Turning in Wood and Metals Masonry, embracing Stonework, Brickwork, Terracotta, and Concrete Roofing with Thatch, Tiles, Slates, Felt, Zinc, &c. Glazing with and without putty, and lead glazing Plastering and Whitewashing Paper-hanging Gas-fitting Bell-hanging, ordinary and electric Systems Lighting Warming Ventilating Roads, Pavements, and Bridges Hedges, Ditches, and Drains Water Supply and Sanitation Hints on House Construction suited to new countries. London: E. & F. N. SPON, 125, Strand. New York : 12, Cortlandt Street. YB. 51971